Title of Invention	POWER UNIT
Abstract	Providing a low-cost power unit having a heel guide to serve also as an air duct, resulting in reduced numbers of components and assembly man-hours required. [Solution] A power unit is provided, wherein: a pillion step (15r) is projectedly provided on a side of a motorcycle body; a heel guide member (150) is attached, overlappingly from a side, to a front portion of a transmission case cover (36) which covers a side of a power transmission mechanism; a projecting guide portion (150u) of the heel guide member (150) is provided on an inner side, in a motorcycle width direction, of and closely to the pillion step (15r); a case air intake port (36c) is formed in a front portion of the transmission case cover (36) being overlapped by the heel guide member (150); and in the heel guide member (150), an air intake port (154) is formed in the guide portion (150u) projecting beyond the transmission case cover (36), and an air passage (160) leading from the air intake port (154) to the case air intake port (36c) is formed. [Selected Drawing] Fig. 1

Title of Invention

POWER UNIT

Abstract

Providing a low-cost power unit having a heel guide to serve also as an air duct, resulting in reduced numbers of components and assembly man-hours required. [Solution] A power unit is provided, wherein: a pillion step (15r) is projectedly provided on a side of a motorcycle body; a heel guide member (150) is attached, overlappingly from a side, to a front portion of a transmission case cover (36) which covers a side of a power transmission mechanism; a projecting guide portion (150u) of the heel guide member (150) is provided on an inner side, in a motorcycle width direction, of and closely to the pillion step (15r); a case air intake port (36c) is formed in a front portion of the transmission case cover (36) being overlapped by the heel guide member (150); and in the heel guide member (150), an air intake port (154) is formed in the guide portion (150u) projecting beyond the transmission case cover (36), and an air passage (160) leading from the air intake port (154) to the case air intake port (36c) is formed. [Selected Drawing] Fig. 1

Full Text	[Document Name] Specification [Title of the Invention] POWER UNIT [Technical Field] [0001] The present invention relates to a swing-type power unit including an internal combustion engine, a power transmission mechanism rearwardly extending from the internal combustion engine, and a rear wheel journaled to a rear portion of the power transmission mechanism which are unitedly and swingably supported by a motorcycle body frame. [Background Art] [0002] There has been an example of the above type of power unit, wherein a transmission case cover covering a side of a power transmission mechanism is provided with a heel guide which guides a heel placed on a pillion step by the passenger sitting on the rear-seat of the motorcycle while preventing the motorcycle body from being damaged by the heel (see the patent document 1, for example). [0003] [Patent Document 1] JP-A No. 2000-40173 [0004] According to the patent document 1, the power transmission mechanism included in the power unit is provided with an air intake and exhaust mechanism for taking in cooling air from the outside and exhausting it. In the power unit disclosed in the patent document 1, an air duct upwardly extends from a front upper portion of a > transmission case cover with an upwardly open intake port formed at an end of the air duct. [Disclosure of the Invention] [Problem to be Solved by the Invention] [0005] In the power unit described above, an air duct and a heel guide are discretely provided. This causes more components and more assembly man-hours to be required, resulting in a higher production cost. [0006] The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a low-cost power unit having a heel guide to serve also as an air duct, resulting in reduced numbers of components and assembly man-hours required. [Means for Solving the Problem] [0007] To achieve the above object, the invention according to Claim. -1 provides a swing-type power unit of a motorcycle, including an internal combustion engine, a power transmission mechanism rearwardly extending from the internal combustion engine, and a rear wheel journaled to a rear portion of the power transmission mechanism which are unitedly and swingably supported by a motorcycle body frame. In the power unit: a pillion step is projectedly provided on a side of a motorcycle body; a heel guide member is attached, overlappingly from a side, to a front portion of a transmission case cover which covers a side of the power transm-ission mechanism; a projecting guide portion of the heel guide member is provided on an inner side, in a motorcycle width direction, of and closely to the pillion step; a case air intake port is formed in a front portion of the transmission case cover being overlapped by the heel guide member; and, in the heel guide member, an air intake port is formed in the guide portion projecting beyond the transmission case cover, and an air passage leading from the air intake port to the case air intake port is formed. [0008] The invention according to Claim 2 provides the power unit according to Claim 1, wherein: the guide portion of the heel guide member projects above the transmission case cover to be lower than a body cover as seen in a side view; and the air intake port is opened in a side toward a r motorcycle width center of the guide portion. [0009] The invention according to Claim 3 provides the power unit according to one of Claims 1 and 2, wherein the guide portion of the heel guide member hides, from outside, an air intake port of an air cleaner. [0010] The invention according to Claim 4 provides the power unit according to one of Claims 2 and 3, wherein: in the air passage of the heel guide member, at least one projecting strip is formed, the projecting strip covering, at a location below the air intake port and above the case air intake port, the case air intake port; and at least one of the. at least one projecting strip forms a drain passage by extending downward beside the case air intake port. [Effect of the Invention] [0011] In the power unit according to Claim 1, the heel guide member includes an air intake port formed in the guide portion projecting beyond the transmission case cover and an air passage which leads from the air intake port to the case air intake port and which serves also as an air duct. The heel guide member can therefore introduce the outside air for cooling the power transmission mechanism while guiding the heel of the passenger's foot placed on a pillion step. This enables a cost reduction by decreasing the numbers of components and assembly man-hours required. [0012] In the power unit according to Claim 2, the air intake port is provided in the guide portion of the heel guide member with the guide portion projecting above the transmission case cover, and the air intake port is opened in a side toward a motorcycle width center of the guide portion. It is, therefore, possible to more effectively prevent mud and water from entering through the air intake port. The guide portion where the air intake port- is provided is positioned lower than the body cover as seen in a side view and externally exposed. It is therefore possible to take in unheated outside air of a relatively low temperature and improve - the cooling efficiency for the power transmission mechanism. [0013] In the power unit according to Claim 3, the guide portion of the heel guide member hides, from outside, the air intake port of the air cleaner. It is therefore possible to prevent foreign matter, for example, mud and water from entering the air cleaner. [0014] In the power unit according to Claim 4: the air passage of the heel guide member includes at least one projecting strip covering, at a location below the air intake port and above the case air intake port, the case air intake port; and at least one of the at least one projecting strip forms a drain passage by extending downward beside the case air intake port. Therefore, if mud or water enters the air passage of the heel guide member, it is guided into the drain passage formed, in a simple configuration, by the projecting strip provided in the air passage to be eventually discharged. It is, therefore, possible to prevent foreign matter from entering the power transmission mechanism. [Best Mode for Carrying Out the Invention] [0015] An embodiment of the present invention will be described below with reference to Figs. 1 to 16. Fig. 1 is a side view of a scooter-type motorcycle according to an embodiment of the present invention. In the following description of the embodiment, the directions front, rear, left, and right are as seen in the forward direction of the scooter-type motorcycle 1. [0016] A motorcycle body front portion IF and a motorcycle body rear portion IR are connected to each other via a low floor portion IC, and a motorcycle body frame making up a motorcycle body skeleton includes a downtube 3 and main pipes 4. The downtube 3 extends downwardly from a headpipe 2 included in the motorcycle body front portion IF. The downtube 3 is bent at its lower end portion into a horizontal direction to further extend rearwardly below the floor portion IC. The left and right main pipes 4 are connected to a rear end portion of the downtube 3. The main pipes 4 extend, from where they are connected to the downtube 3, rearwardly and upwardly to be then bent at a predetermined height into a horizontal direction to further extend rearwardly. [0017] The main pipes 4 support a fuel tank and a storage box with a seat 5 disposed' over them. The seat 5 is longitudinal in the front-rear direction. It includes a driver seat 5f formed in a front half portion thereof and a pillion 5r formed rearward of the driver seat 5f. The motorcycle body front portion IF includes a handlebar 6 disposed in an upper portion thereof and a front fork 7 extending in a lower portion thereof. The handlebar 6 is journaled to the headpipe 2. A front wheel 8 is journaled to a lower end portion of the front fork 7. [0018] A bracket 4a is projectedly provided at a lower end portion of the rearwardly upwardly extending main pipes 4. A swing-type power unit 10 is swingably linked to and supported by the bracket 4a via a link member 9. Figs. 2, 3, and 4 show a side view, a plan view, and a front view of the power unit 10, respectively. [0019] A single-cylinder, four-stroke internal combustion engine 30 is installed in a front portion of the power unit 10, the internal combustion engine 30 being tilted forward to such an extent that a cylinder block 32 is almost horizontally positioned. A hanger bracket 10a is forwardly projecting from a lower end portion of the portion corresponding to the crankcase of a unit case 31. An end portion of the hanger bracket 10a is linked to the link member 9 via a pivot shaft 9a (see Fig. 1). [0020] A continuously variable belt-type transmission 35 is configured in an area ranging from the internal combustion engine 30 to an area rearward of the internal combustion engine 30. A rear wheel 21 is journaled to a speed reduction mechanism 38 provided in a rear portion of the transmission'35. A rear cushion 22 is disposed between a rear end portion of the unit case 31 and a rear portion of the main pipes 4. [0021] A carbureter 24 which is connected to an inta"ke pipe 23 extending from an upper portion of a cylinder head 33 of the internal combustion engine 30 and an air cleaner 25 coupled to the carburetor 24 are disposed above the power unit 10. A main stand 26 is pivotally attached to the hanger bracket 10a projectedly provided in a lower portion of the unit case 31 . [0022] Referring to Fig. 1, a front portion and a rear portion of the motorcycle body front portion IF are covered by a front cover 11 and a rear cover 12, respectively; a left side and a right side of the motorcycle body front portion IF are covered by a front lower cover 13; and a central portion of the handlebar 6 is covered by a handle cover 14 . A step plate 15 is installed in the floor portion IC. The step plate 15 includes a horizontal floor step portion 15f and a pillion step portion 15r extending, on the left and right sides, rearwardly and upwardly. The pillion step portion 15r projects horizontally and laterally so that the passenger sitting on the pillion 5r can rest, on each side, his or her foot F (shown in dotted line in Fig, 1) on it. [0023] A lower side cover 16 extends, below the step plate 15, alpng the edge on each side of the step plate 15. The motorcycle body rear portion IR is connected 'to an upper portion of the pillion step portion 15r of the step plate 15. A body cover 17 covers a portion of the motorcycle body rear portion IR, the portion extending from a location forward of the main pipes 4 to left and right sides of the motorcycle body rear portion IR. An upper-end opening of the body cover 17 is openably covered by the seat 5. [0024] As seen in a side view, a rear fender 18 extends rearwardly and downwardly from a rear portion of the body cover 17 thereby covering the rear wheel 21 from above, the rear portion of the body cover 17 extending rearwardly and upwardly tobegraduallythinner. [0025] As seen in a left side view (see Fig. 1), the rear end portions 17e, 15e, and 16e, being successively overlaid, of the body cover 17, step plate 15, and lower side cover 16 are generally inclined rearwardly. Portions around where the step plate 15 and the lower side cover 16 are fitted to each other of the rear end portions 15e and 16e project rearwardly. A horizontal portion included in the rearwardly projecting portion of the rear end portion 15e of the pillion step portion 15r is designed to be where the passenger rests the heel Fh of his or her foot F. [0026] An upper portion of the rearwardly projecting portion of the, rear end portion 15e of the step plate 15 is shaped to be forwardly concave and continuous with the rear end portion 17e of the body cover 17, thereby forming a concave 19. Therefore, when the passenger rests the heel Fh of his or her foot F on the pillion step portion 15r, there is the uncovered concave 19 on the inside of the heel Fh placed on the pillion step portion 15r (see Fig. 1) . [0027] Fig. 5 is a cross-sectional view, taken generally along line V - V in Fig. 2, of the power unit 10 [0028] The unit swing case 31 includes a left unit case 31L and a right unit case 31R which are coupled together. The right unit case 31R makes up one half part of a crankcase section. The left unit case 31L includes a crankcase section 31a which is longitudinal in the front-rear direction, a transmission case section 31b, and a reduction gear case section 31c, the three sections being located in a front portion, a center portion, and a rear portion of the left unit case 31L, respectively. [0029] The left open side of the left unit case 31L is covered by a transmission case cover 36 which is a part of the transmission case. The continuously variable belt-type transmission 35 is housed in the left unit case 31L. The right open side of the reduction gear case section 31c located in the rear portion of the left unit case 31L is covered by the reduction gear case 37. The speed reduction mechanism 38 is housed in the left unit case 31L. [0030] In the so-called crankcase including the crankcase section 31a and the right unit case 31R, a crankshaft 40 is rotatably supported by left and right main bearings 41, the crankshaft 40 horizontally extending beyond the left and right main bearings 41. An AC generator 60 is provided on the right extending portion of the crankshaft 40. A cam chain drive sprocket 55 and a belt drive pulley 76 of the continuously variable belt-type transmission 3 5 are provided on the left extending portion of the crankshaft 40 [0031] In the internal combustion engine 30, a piston 42 which reciprocates in a cylinder liner 44 of a cylinder block 32 and a crankpin 40a of the crankshaft 40 are linked by a connecting rod 4 3. The present four-cycle internal combustion engine 30 employs a SOHC valve system. A valve mechanism 50 is provided in a cylinder head cover 34. A cam chain 51 for driving the valve mechanism 50 is wound between a cam shaft 54 and the crankshaft 40. A cam chain chamber 52 is formed through the crankcase section 31a, cylinder block 32, and cylinder head 33. [0032] Namely, the cam chain 51 is wound, through the cam chain chamber 52, between a driven sprocket 54 fitted to a left end portion of a cam shaft 53 which is horizontally oriented in the lateral direction and the drive sprocket 55 fitted, to the crankshaft 40. A spark plug 45 is fitted into the cylinder head 33 diagonally from the opposite side to the cam chain chamber 52 (from the right side) toward a combustion chamber. [0033] The valve mechanism 50 is provided inside the cylinder head cover 34 as shown in Fig, 6. With the cylinder largely inclined forwardly into a nearly horizontal position, an intake valve 56 and an exhaust valve 57 are provided above and below the cam shaft 53, respectively. A rocker arm 59i and a rocker arm 59e are rockably fitted to an upper rocker shaft 58i and a lower rocker arm 58e, respectively. As the cam attached to the cam shaft 53 turns, the rocker arms 59i and 59e are rocked to open and close the intake valve 56 and the exhaust valve 57 at predetermined timing. [0034] The AC generator 60 is provided on the right side surface of the right unit case 31R. A bowl-shaped outer rotor 62 is fixed, via an ACG boss 61, to an end portion of the crankshaft 4 0 projecting from a central cylindrical portion 31d of the right unit case 31R. A magnet 63 is circumferentially disposed along the inner circumference of the outer rotor 62. Inside the magnet 63, a stator 64 around which a stator coil 65 is wound is fixed to the central cylindrical portion 31d. [0035]■ . . ' A forced-cooling fan 66 is attached on the right side face of the outer rotor 62. The side of the fan 66 is covered by a"fan cover 67. A shroud 68 surroundingly covering the cylinder block 32 and cylinder head 33 is provided continuously with the fan cover 57. [0036] In the crankcase section 31a of the unit swing case 31, the cam chain chamber 52 is formed being separated from the crankcase by the main bearing 41. The left side wall of the cam chain chamber 52 forms a separation wall 71 which separates the continuously variable belt-type transmission chamber 70 to the left of the separation wall 71 from the cam chain chamber 52. A circular through hole 71a, through which the crankshaft 40 extends, is formed through the separation wall 71, the through hole 71a having a flat cylindrical shape with a large diameter. An annular sealing member 72 is press-fitted in the through hole 71a. The crankshaft 40 extends through the hollow portion of the annular sealing member 7 2. [0037] The drive sprocket 55 is fitted in a portion between the sealing member 72 and the main bearing 41 of the crankshaft 40. The cam chain 51 is wound on the drive sprocket 55. The sealing member 72 watertightly separates the continuously variable belt-type transmission chamber 7 0 and the cam chain chamber 52, so that oil leakage from the latter to the former is prevented. A belt drive pulley 76 is rotatably provided on the ciranks'haft 4 0 extending through the sealing member 7 2. [0038] The belt drive pulley 76 includes a fixed pulley half 7 7 and a movable pulley half 78. The fixed pulley half 77 is fixed, via a boss 79, to a left end portion of the crankshaft 40. The movable pulley half 78 is spline-fitted, on the right of the fixed pulley half 77, to the crankshaft 40. The movable pulley half 78 rotates together with the crankshaft 40. While rotating, the movable pulley half 78 can axially slide toward or away from the fixed pulley half 77. A V-belt 75 is rotatably held between the fixed pulley half 77 and the movable pulley half 78. [0039] A cam plate 80 is fixedly provided, closely to the annular sealing member 72, to the right of the movable pulley half 78. A slide piece 80a provided in an outer peripheral end portion of the cam plate 80 is slidably engaged with a cam plate sliding boss portion 78a axially formed in an outer peripheral end portion of the movable pulley half 78. The side surface on the cam plate 80 side of the movable pulley half 78 is tapered toward the cam plate 80. A dry weight roller 81 is accommoda'ted on the inner side of the tapered surface, that is, between the tapered surface and the cam plate 80. [0040] When the rotation speed of the crankshaft 40 increases, the dry weight roller 81 also rotating between the mO'Vable pulley half 78 and the cam plate 80 is centrifugally moved in the centrifugal direction to push and move the movable pulley half 78 leftward closer to the fixed pulley half 77. As a result, the V-belt 75 held between the pulley halves 77 and 78 is moved in the centrifugal direction to increase the winding diameter. [0041] A belt-driven pulley 86 corresponding to the belt-drive pulley 76 is disposed rearward of the belt drive pulley 76 and includes a fixed pulley half 87 and a movable pulley half 88. The fixed pulley half 87 is fitted to ah inner sleeve 89 which is supported to be rotatable relative to a speed reducer input shaft 92 of the speed reduction mechanism 38. The movable pulley half 88 is fitted to an outer sleeve 90 which is axially movably supported, to the left of the fixed pulley half 87, by the inner sleeve 8 9. The V-belt 75 is held between the pulley halves 87 and 88. [0042] A centrifugal clutch 91 is provided on the left side of the speed reducer input shaft 92 and inner sleeve 89, When the rotation speed of the inner sleeve 89 increases, the centrifugal clutch 91 engages to transmit the power transmitted to the inner sleeve 89 via the V-belt 7 5 to the speed reducer input shaft 92. In the speed reduction mechanism 38, the power transmitted to the speed reducer input shaft 92 is transmitted to an output shaft 94 via an intermediate shaft 93, that iS/ the rotation of the input shaft 92 is transmitted to the output shaft 94 after deceleration by means of a gear engagement. The output shaft 94 makes up a rear wheel shaft to rotate the rear wheel 21. [0043] Referring to Fig. 5, a transmission case cover 36 covering the continuously variable belt-type transmission chamber 70 from the left side covers a portion of the continuously variable beIt-type transmission chamber 7 0 extending from the belt-drive pulley 76 on the front side to the centrifugal clutch 91 on the rear side. A kick shaft 27 is rotatably inserted through and supported at a portion slightly forward of a middle portion of the transmission case cover 36, A drive helical gear 100 is fitted to an inner end portion of the kick shaft 27. The drive helical gear 100 is biased by a return spring 101. [0044] A sliding shaft 102 is supported at a front inner portion of the transmission case cover 36 coaxially with the crankshaft 4 0, rotatably, and axially slidably. A driven helical gear 103 is formed on the sliding shaft 102 and is engaged with the drive helical gear 100. A ratchet wheel 104 is fixed to a right end portion of the driven helical gear 103. These parts as a whole are biased leftward by a friction spring 105. On the boss 79 on the crankshaft 40 side, a ratchet 7 9a opposing the ratchet wheel 104 is formed. They can be brought into or out of contact with each other by sliding t'he sliding shaft 102 [0045] When a kick pedal is pressed down and the kick shaft 27 rotates opposing the return spring 101, the drive helical gear 100 rotates integrally with the kick shaft 27, This causes the driven helical gear 103 engaged with the drive helical gear 100 to rotate integrally with the sliding shaft 102 and slide rightward opposing the friction spring 105. As a result, the ratchet wheel 104 engages the ratchet 79a formed on the boss 79, and the crankshaft 40 is forcedly rotated to start the internal combustion engine 30 [0046] In the present internal combustion engine, a starter motor 110 is disposed above the crankcase section 31a of the left unit case 31L. As shown in Fig. 7, the starter motor 110 includes a leftwardly projecting pinion .113 around which an inner rotor coil 112 surrounded by an outer Stator magnet 111 is wound. A gear 113a is formed at an end portion of the pinion 113. [0047] A jump gear mechanism 115 held between the crankcase section 31a and the transmission case cover 36 is positioned between the starter motor 110 and the belt-drive pulley 76 with its shaft laterally horizontally oriented. The pinion gear 113a of the starter motor 110 is engaged with an input gear 116 disposed to the right of the jump gear mechanism 115. A left jump gear 117 is disposed to the left of the jump'gear mechanism 115. When the left jump gear 1.17 jumps out leftward, it engages a starter ring gear 77a formed on an outer peripheral edge of the fixed pulley half 77. [0048] Therefore, when the starter motor 110 is started, the rotation of the pinion 113 is transmitted to the input gear 116 of the jump gear mechanism 115, causing the jump gear 117 to jump out leftward and engage the starter ring gear 77a of the fixed pulley half 77. As a result, the fixed pulley half 77 rotates together with the crankshaft 40 to start the internal combustion engine 30. When the starter motor 110 stops, the j ump gear 117 retracts to be disengaged from the starter ring gear 77a. [0049] The fixed pulley half 77 on which the starter ring gear 77a to be engaged with the jump gear 117 is formed has a cooling fan 118 made of iron and bolted (not shown) to its side (left side) opposite to the side where the V-belt 75 is held. The cooling fan 118 operates to take in the outside air for cooling the continuously variable belt-type transmission 35. [0050] The transmission case cover 36 includes a side wall and a peripheral wall, the former covering a left side portion and the latter surrounding an outer peripheral portion, respectively, of the continuously variable belt-type transmission 35. As shown in Fig. 8, the side wall includes, in a front portion thereof, a concave wall portion 36a which is continuous, via a step 36b, with the remaining portion of the side wall. The concave wall portion 36a has a c-ase air intake port 36c which, facing leftward, has a deformed rectangular shape. As shown in broken line in Fig. 8, a cylindrical case air exhaust duct 36d is formed to extend, in an approximately central portion in the front-rear direction of the side wall, in a diagonal upward-downward direction along the inner surface of the side wall. The upper end of the exhaust duct 36d is opened to the chamber interior. The lower end is opened to the outside. [0051] Hence, the case air intake port 36c in a front portion of the transmission case cover 36 is opened toward the cooling fan 118 heat-bonded to the fixed pulley half 77 (see Fig. 5). The rotation of the cooling fan 118 can take cooling air into the continuously variable belt-type transmission chamber 70 through the case air intake port 35c. The cooling air having cooled the continuously variable belt-type transmission 35 can be exhausted to the outside through the case air exhaust duct 36d. [0052] A support 36e to support the jump gear 117 is formed in an upper portion of the concave wall portion 36a provided in a front portion of the transmission case cover 36, the support 36e having a partially circular conic shape Bolt holes 36i and 36j are formed above and below the case air intake port 36c, respectively. A heel guide member 150 serving also as an air intake duct is fitted to the concave wall portion 36a provided in a front portion of the transmission case cover 36. An inner wall member 151-and an outer wall cover member 161 of the heel guide member 150 are united to form an air intake duct which internally provides air passage space. [0054] As shown in Figs. 9 to 11, the inner wall member 151 includes an inner wall 152 which is shaped like a pectoral fin of a fish as seen in a side view (see Figs. 9 and 10). The inner wall 152 includes an upper wall portion 152u, a lower wall portion 1521, and a slanted wall portion 152s, the three wall portions being vertical as seen in a front view and shaping the inner wall 152 such that the upper wall portion 152u and the lower wall portion 1521 being laterally shifted from each other are linked by the slanted wall portion 152s (see Fig. 11). A peripheral wall 153 is projectedly formed on the left side surface of the inner wall 152 to be slightly inside the peripheral edge of the inner wall 152 (see Fig. 9) . [0055] The upper wall portion 152u of the inner wall 152 includes an air intake port 154 formed inside the peripheral wall 153. A louver 155 is installed over the air intake port 154. In the lower wall portion 1521 of the inner wall 152, a connection port 152c corresponding to the case air intake port 3 6c formed in the concave wall portion 3 6a is formed. In the slanted wall portion 152s, a circular conic portion 152e corresponding to the circular conic support 36e formed on the transmission case cover 36 is formed. [0056] On the left side surface of the inner wall 152, a projecting strip is projectedly formed to extend curvedly forwardly and downwardly from above the connection port 152c along a front side of the connection port 152c. A front lower portion of the projecting strip 156 extends downwardly in parallel with a front side portion of the peripheral wall 153, forming a drain passage 170 between them. The drain passage 170 has an open lower end. [0057] A linear projecting strip 157 is projectedly formed upward of the projecting strip 156 and downward of the air intake port 154. The projecting strip 157 extends, below the air intake port 154, forwardly and slightly downwardly from a rear edge portion of the peripheral wall 153. A rear portion of the lower projecting strip 156 is positioned below a front portion of the upper projecting strip 157, forming an air passage 160 between them. [0058] A cutout 153b is formed at a location downward of a rear end portion of the projecting strip 156, the location being in a slanted rear edge portion of the peripheral wall 153. A fixing hole 158i is formed in an upper end portion of the portion below the cutout 153b of the peripheral wall 153. .A projecting strip 153a extends forwardly and upwardly from the fixing hole 158i. The fixing hole 158i is located above the connection port 152c and corresponds to the bolt hole 36i formed in the transmission case cover 36. A fixing hole 158j corresponding to the bolt hole 36j is formed below the connection port 152c. [0059] A catching projection 159p is projectedly formed on a rear edge portion, which is more rearwardly positioned than the air intake port 154, of the upper wall portion 152u of the inner wall 152. Another catching projection 159q is projectedly formed on a curved lower front edge portion of the lower wall portion 1521. [0060] As shown in Figs. 12 to 14, the outer wall cover member 161 includes an outer wall 162 which is shaped approximately the same as the inner wall 152 of the inner wall member 151 as seen in a side view (see Figs. 12 and 13). The outer wall 162 includes an upper wall portion 162u, a lower wall portion 1621, and a slanted wall portion 162s, the three wall portions being vertical as seen in a front view and shaping the outer wall 162 such that the upper wall portion 162u and the lower wall portion 1621 being I'aterally shifted from each other are linked by the slanted wall portion 162s (see Fig. 14). A peripheral wall 163 slightly larger than the peripheral wall 153 of the inner wall member 151 is projectedly formed on the right side surface of and along the peripheral edge of the outer wall 162 (see Fig. 13). [0061] A projecting strip 166 is projectedly formed on the right side surface of the outer wall 162, the projecting strip 166 being shaped to fit the upper side of the projecting strip 156 curvedly formed on the left side surface of the inner wall 152. Thus, the drain passage 170 is also formed between the projecting strip 166 and the peripheral wall 163. A projecting strip 167 is projectedly formed upward of the projecting strip 166, the projecting strip 167 being shaped to fit the upper side of the linear projecting strip 157 formed on the left side surface of the inner wall 152. [0062] Fixing holes 168i and 168j corresponding to the fixing holes 158i and 158j are formed in a middle portion and a lower end portion of the rear slanted portion of the peripheral wall 163. Catching pieces 169p and 169q corresponding to the catching projections 159p and 159q are formed in an upper rear edge portion and a lower front edge portion, respectively, of the peripheral wall 163. The catching piece 169p is shaped like a hook to catch -and engage the catching projection 159p. The catching piece 169q has a hole into which the catching projection 159 is inserted for engagement. [0063] The inner wall member 151 and the outer wall cover member 161 are joined together by aligning the inner wall 152 and the outer wall 162 such that they face each other and fitting the peripheral wall 163 of the outer wall cover member 161 around the outer periphery of the peripheral wall 153 of the inner wall member 151. In doing this, first, the catching projection 159q of the inner wall member 151 is inserted into the catching piece 169q of the outer wall cover member 161 thereby engaging the two parts, and then the inner wall member 151 and the outer wall cover member 161 are joined together by fitting the peripheral wall 153 and the peripheral wall 163 to each other. When this is done, the catching projection 159p of the inner wall member 151 is caught by the catching piece 169p of the outer wall cover member 161. As a result, the inner wall member 151 and the outer wall cover member 161 are united into an air intake duct, i.e. the heel guide member 150. [0064] Inside the heel guide member (the air intake duct) 150, an air passage 160 is formed by the linear upper projecting strips 157 and 167 and the curved lower projecting strips 156 and 166. The air passage 160 has a labyrinth structure and leads from the air intake port 154 formed in an upper portion of the inner wall 152 to the c'onnection port 152c formed in a lower portion of the inner wall 152. If mud or water enters the air passage 160 through the air intake port 154, the mud or water flows forward over the upper surfaces of the inclined upper projecting strips 157 and 167, drops from the front ends of the inclined upper projecting strips 157 and 167 onto the lower projecting strips 156 and 166. The mud or water then further flows forward over the curved projecting strips 156 and 166, that is, down through the drain passage 170 to be subsequently discharged to the outside. [0065] The heel guide member 150 is fitted to the concave wall portion 36a formed in a front portion of the transmission case cover 36. In doing this, the lower wall portions 1521 and 1621 and slanted wall portions 152s and 162s of the heel guide member 150 are fitted to the concave wall portion 36a, and the mutually fitted fixing holes 158i and 168i and the mutually fitted fixing holes 158j and 168j are fitted to the corresponding bolt holes 36i and 36j, respectively, formed in the transmission case cover 36. Bolts 171 and 172 are then inserted through the corresponding fixing holes and bolt holes thus fitted together and tightened to fix the heel guide member 150 to the transmission case cover 36 [0066] When the heel guide member 150 has been fixed to the transmission case cover 36, the outer surface of the outer wall cover member 161 is coplanar with the outer surface of the transmission case cover 36, and the connection port 152c formed in a lower portion of the inner wall member 151 is connected to the case air intake port 36c formed in the transmission case cover 36. [0067] The upper wall portions 152u and 162u of the heel guide member 150 are upwardly projecting above the transmission case cover 36 while curving toward the motorcycle inside. The air intake portion 154 formed in the upper wall portion 152u of the inner wall member 151 is rightwardly (toward the motorcycle inside) open, The louver 155 provided at the air intake port 154 faces the right (the motorcycle inside) with its blades inclined rightwardly (toward the motorcycle inside) and downwardly not to easily allow mud or water to enter the air intake port 154 from above. [0068] As described above, the heel guide member 15 0 to serve also as an air intake duct is attached to a front portion of the transmission case cover 36. Therefore, when the cooling fan 118 attached to the fixed pulley half 77 of the continuously variable belt-type transmission 35 rotates, the outside air is introduced, as a cooling air, from the air intake port 154 of the heel guide member 150 into the continuously variable beIt-type transmission chamber 7 0 via the air passage 160 and the case air intake port 36c, and the cooling air having cooled the continuously variable belt-type transmission 35 is exhausted from the case air exhaust duct 36d to the outside. [0069] If foreign matter such as mud or water enters the air passage 160 through the air intake port 154, the foreign matter is discharged to the outside through the drain passage 170 formed by the projecting strips 157 and 167 and the projecting strips 156 and 166, so that foreign matter is prevented from entering the continuously variable belt-type transmission 7 0. [0070] The upper wall portions 152u and 162u projecting above the transmission case cover 36 of the heel guide member 150 make up a guide portion 150u. As shown in Fig. 1, the guide portion 150u is partly overlapped, as seen in a side view, by a rear end portion of the pillion step portion 15r of the step plate 15 and extends upward covering the concave 19 formed above the overlapped portion. The heel portion Fh of the passenger's foot F (shown in two-dot chain line in Fig. 1) placed on the pillion step portion 15r is guided in place by the guide portion 150u closing the concave 19 from an inner side of the motorcycle. [0071] In the air cleaner 25 disposed upward of the crankcase section of the internal combustion engine 30, a rear portion of a container 25a is laterally bulging to both sides, and an intake duct 25b extends forward from the left bulging portion along the left wall of the container 2'5a. A cleaner air intake port 25i which is opened at a front end of the intake duct 25b is inwardly separated from the guide portion 150u of the heel guide member 150 (see Figs. 3 and 4) and overlaps with the guide portion 150u as seen in a side view (see Fig. 2). [0072] Thus, with the guide portion 150u of the heel guide member 150 covering, from outside, the cleaner air intake port 25i of the air cleaner 25, foreign matter, for example, mud or water is prevented from entering the air cleaner 25. [0073] The shroud 68 covering the periphery of the cylinder block 32 and cylinder head 33 of the internal combustion engine 30 has a rectangular opening in its front end portion and, as shown in Figs. 2 to 5, the cylinder head cover 34 is fitted through and projecting forward from the rectangular opening. An upper wall 68u, a lower wall 68d, and a left wall 681 extend rearward from the rectangular opening along the sides of the cylinder head 33 and cylinder block 32. The right wall 68r largely bulges rightward to be increasingly separated from the cylinder head 33 and cylinder block 32 until being connected to the fan cover 67. [0074] The fan cover 67 includes an annular frame 67a whose central axis is the crankshaft 40. A front periphera-1 portion of the annular frame 67a is screwed, with a screw 120, to a rear end portion of the right wall 68r of the shroud 68. The portion other than the front peripheral portion of the annular frame 67a is fixedly bolted, with a bolt 121, to a right edge portion of the right unit case 31R. The fan cover 67 is regarded as an extension member of the shroud 68, and a cooling air intake port 67i is provided, facing the forced-cooling fan 66, in the right wall (see Fig, 5) . [0075] A cooling air outlet port 68e is opened in a rear lower-half portion of the left wall 681 of the shroud 68 with a front end portion of the air exhaust duct 69 connected to the cooling air outlet port 68e. The air exhaust duct 69 extends leftward from the cooling air outlet port 68e provided in the left wall 681 and then curves rearwardly and downwardly to further extend, being partly fitted to the concave wall portion 36a of the transmission case cover 36, along the lower end surface of the heel guide member 150 until reaching the step 36b of the transmission case cover 36 where a rear-end air exhaust port 69e is opened rearwardly and downwardly (see Figs. 2, 3, and 4) . [0076] The shroud 68 surroundingly -covering the cylinder block 32 and cylinder head 33 includes the cooling air intake port 67i provided in the fan cover 67 that is a rearward extension of the right wall 68r and the cooling air outlet port 68e formed in the left wall 681 opposing the right wall 68r. Therefore, as seen in Fig. 5, the cooling air sucked in from the cooling air intake port 67i by the rotation of the forced-cooling fan 66 flows, while being diagonally forwardly guided by the curved right wall 68r, leftward passing around the peripheral portions of the cylinder block 32 and cylinder head 33, thereby cooling the cylinder block 32 and cylinder head 33. The cooling air having cooled the cylinder block 32 and cylinder head 33 flows out of the cooling air outlet port 68e provided in the left wall 681 without changing the flow direction. [0077] Thus, the cooling air flows evenly and smoothly, without becoming locally stagnant, through the inside of the shroud 68 unidirectionally from the cooling air intake' port 67i to the cooling air outlet port 68e before being let out from the air exhaust duct 69. The cooling air can, therefore, cool the portions to be cooled of the cylinder block 32 and cylinder head 33 of the internal combustion engine 30 thoroughly and efficiently. Furthermore, with the passage resistance being small and the cooling air volume being large, a great cooling effect can be expected. [0078] Referring to the side view shown in Fig. 2 of the power unit 10, the air exhaust duct 69 is located below the cylinder axis C -- C that is the central axis of the cylinder bore of the cylinder block 32. Referring to the front view shown in Fig. 4 of the power unit 10, the air exhaust duct 69 is located, in the motorcycle width direction, approximately outside (to the right of, as seen in Fig. -4) the air cleaner 25 and inside (to the left of, as seen in Fig. 4) the outer surface of the transmission case cover 36. [0079] Thus, the air exhaust duct 69 is small and can be compactly installed on the left of the shroud 68 to extend along the lower end surface of the heel guide member 150. This makes the air exhaust duct 69 less conspicuous resulting in better appearance. [0080] The cleaner air intake port 25i of the air cleaner 25 and the air intake port 154 of the heel guide member (air intake duct) 150 are both located higher than the cylinder axis C -- C as seen in a side view (see Fig. 2). [0081] Namely, whereas the air exhaust port 69e of the air exhaust duct 69 is located below the cylinder axis C -- C, the cleaner air intake port 25i and the air intake port 154 are located higher than the cylinder axis C -- C. Moreover, the heel guide member 150 and the transmission case cover 3 5 exist between them. Therefore, the warm exhaust air coming out of the air exhaust port 69e below the heel guide member 150 mostly flows rearward along the lower surface of the transmission case cover 36. If part of the exhaust air flows upward along the side surface of the transmission case cover 36, it is unlikely to be sucked into the cleaner air intake port 25i or the air intake port 154. This can prevent the intake air temperature from rising and the cooling efficiency for the continuously variable beIt-type transmission 35 from lowering. [0082] The air intake port 154 is located, in the motorcycle width direction, between the cleaner air intake port 25i and the air exhaust port 69e of the air exhaust duct 69 (see Fig, 4), Therefore, if the engine cooling air exhausted from the air exhaust port 69e flows upward, for example, when the motorcycle is stopped, the exhaust air is likely to be led to the nearer air intake port 154 before reaching the farther cleaner air intake port 25i, so that the exhaust air is quite unlikely to be sucked into the farther cleaner air intake port 25i. This can prevent the intake air temperature from rising. [0083] Furthermore, the heel guide member (air intake duct) 150 and the cleaner air intake port 25i are located to overlap with each other as seen in a side view, so that the guide portion 150u serves as an external guide to securely prevent the engine cooling air exhausted from the air exhaust port 59e from being sucked into the cleaner air intake port 25i. This makes it more possible to prevent the intake air temperature from rising and foreign matter, for example, mud or water from entering through the cleaner air intake port. As described above, the heel guide member 150 is configured to serve also as an air intake duct. Namely, it can introduce the outside air for cooling the continuously variable belt-type transmission 35, whereas the guide portion 150u positioned to close, from inside in the motorcycle width direction, the concave 19 formed in a left rear-end portion of the motorcycle body covers 15 and 17 guides the heel Fh of the passenger's foot F in place on the pillion step portion 15r. This enables a cost reduction by decreasing the numbers of components and assembly man-hours required. [0085] The air intake port 154 is formed in a portion, which projects above where the heel guide member 150 is attached to the transmission case cover 36, of the guide portion 150u. Moreover, the air intake port 154 is opened in a side toward the motorcycle width center of the guide portion 150u. It is, therefore, possible to more effectively prevent mud and water from entering through the air intake port 154. [0086] The guide portion 150u including the air intake port 154 is located, as seen in a side view (see Fig. 1), in the concave 19 formed below the body cover 17 and externally exposed. It is, therefore, possible to take in unheated outside air of a relatively low temperature. This can improve the cooling efficiency for the continuously variable belt-type transmission 35. [0087] In the. air passage 160 of the heel guide member 150, the proje.cting strips 156, 166, 157, and 167 are formed, the projecting, strips covering, at locations below the air intake port 154 and above the case air intake port 36c, the case air intake port 35c. The projecting strips 156 and 166 extend downward beside the case air intake port, thereby forming the drain passage 170. If mud or water enters the air passage 170 of the heel guide member 150, it is guided into the drain passage 160 formed, in a simple configuration, by the projecting strips 156 and 166 provided in the air passage 160 to be eventually discharged Thus, it is possible to effectively prevent foreign matter from entering the continuously variable belt-type transmission chamber 7 0. [Brief Description of the Drawings] [0088] [Fig. 1] is an overall side view of a scooter-type motorcycle according to an embodiment of the present invention. [Fig. 2] is a side view of a power unit of the scooter-type motorcycle. [Fig. 3] is a plan view of the power unit of the scooter-type motorcycle. [Fig. 4] is a front view of the power unit of the scooter-type motorcycle. [Fig. 5] is a cross-sectional view taken along line V -'- V in Fig. 2 . [Fig. 6] is a cross-sectional view taken along line VI -- VI in Fig. 5. [Fig. 7] is a cross-sectional view taken along line VII -- VII in Fig. 2. [Fig. 8] is a side view of a transmission case cover [Fig. 9] is a left side view of an inner wall member of a heel guide member. [Fig. 10] is a right side view of the inner wall member of the heel guide member. [Fig. 11] is a cross-sectional view taken along line VII — VII in Fig. 10. [Fig. 12] is a left side view of an outer wall cover member of the heel guide member. [Fig. 13] is a right side view of the outer wall member of the heel guide member. [Fig. 14] is a cross-sectional view taken along line XIV — XIV in Fig. 13. [Fig. 15] is a right side view of the heel guide member wherein the inner wall member and the outer wall cover member are united. [Fig. 16] is a cross-sectional view taken along line XV -- XV in Fig. 15. [Description of Reference Numerals] [0089] 10... Power unit 15... Step plate 15r... Pillion step portion , 17. . . Body cover 19... Concave 25... Air cleaner 251... Cleaner air intake port 30... Internal combustion engine 31... Unit case 36... Transmission case cover 36c... Case air intake port 36d... Case air exhaust duct 118... Cooling fan 119... Exhaust duct 150... Heel guide member (Air intake duct) 150u... Guide portion 151... Inner wall member 152... Inner wall 153... Peripheral wall 154... Air intake port 155... Louver 156... Projecting strip 157... Projecting strip 160... Air passage 161... Outer wall cover member 162... Outer wall 163... Peripheral wall 166... Projecting strip 167.., Projecting strip 170.-. Drain passage [Docuinent Name] Scope of Claims [Claim 1] A swing-type power unit of a motorcycle, comprising an internal combustion engine, a power transmission mechanism rearwardly extending from the internal combustion engine, and a rear wheel journaled to a rear portion of the power transmission mechanism which are unitedly and swingably supported by a motorcycle body frame, wherein: a pillion step is projectedly provided on a side of a motorcycle body; a heel guide member is attached, overlappingly from a side, to a front portion of a transmission case cover which covers a side of the power transmission mechanism; a projecting guide portion of the heel guide member is provided on an inner side, in a motorcycle width direction, of and closely to the pillion step; a case air intake port is formed in a front portion of the transmission case cover being overlapped by the heel guide member; and in the heel guide member, an air intake port is formed in the guide portion projecting beyond the transmission case cover, and an air passage leading from the air intake port to the case air intake port is formed. [Claim 2] The power unit according to Claim 1, wherein: the guide portion of the heel guide member projects above the transmission case cover to be lower than a body cover as seen in a side view; and 'the air intake port is opened in a side toward a motorcycle width center of the guide portion. [Claim "3] The power unit according to one of Claims 1 and 2, wherein the guide portion of the heel guide member hides, from outside, an air intake port of an air cleaner. [Claim 4] The power unit according to one of Claims 2 and 3^ wherein: in the air passage of the heel guide member, at least one projecting strip is formed, the projecting strip covering, at a location below the air intake port and above the case air intake port, the case air intake port; and at least one of the at least one projecting strip forms a drain passage by extending downward beside the case air intake port.

Full Text

[Document Name] Specification [Title of the Invention] POWER UNIT [Technical Field] [0001]
The present invention relates to a swing-type power unit including an internal combustion engine, a power transmission mechanism rearwardly extending from the internal combustion engine, and a rear wheel journaled to a rear portion of the power transmission mechanism which are unitedly and swingably supported by a motorcycle body frame. [Background Art] [0002]
There has been an example of the above type of power unit, wherein a transmission case cover covering a side of a power transmission mechanism is provided with a heel guide which guides a heel placed on a pillion step by the passenger sitting on the rear-seat of the motorcycle while preventing the motorcycle body from being damaged by the heel (see the patent document 1, for example). [0003]
[Patent Document 1] JP-A No. 2000-40173 [0004]
According to the patent document 1, the power
transmission mechanism included in the power unit is
provided with an air intake and exhaust mechanism for
taking in cooling air from the outside and exhausting it.
In the power unit disclosed in the patent document 1, an
air duct upwardly extends from a front upper portion of a >

transmission case cover with an upwardly open intake port
formed at an end of the air duct.
[Disclosure of the Invention]
[Problem to be Solved by the Invention]
[0005]
In the power unit described above, an air duct and a heel guide are discretely provided. This causes more components and more assembly man-hours to be required, resulting in a higher production cost. [0006]
The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a low-cost power unit having a heel guide to serve also as an air duct, resulting in reduced numbers of components and assembly man-hours required. [Means for Solving the Problem] [0007]
To achieve the above object, the invention according to Claim. -1 provides a swing-type power unit of a motorcycle, including an internal combustion engine, a power transmission mechanism rearwardly extending from the internal combustion engine, and a rear wheel journaled to a rear portion of the power transmission mechanism which are unitedly and swingably supported by a motorcycle body frame. In the power unit: a pillion step is projectedly provided on a side of a motorcycle body; a heel guide member is attached, overlappingly from a side, to a front portion of a transmission case cover which covers a side of the power

transm-ission mechanism; a projecting guide portion of the heel guide member is provided on an inner side, in a motorcycle width direction, of and closely to the pillion step; a case air intake port is formed in a front portion of the transmission case cover being overlapped by the heel guide member; and, in the heel guide member, an air intake port is formed in the guide portion projecting beyond the transmission case cover, and an air passage leading from the air intake port to the case air intake port is formed.
[0008]
The invention according to Claim 2 provides the power
unit according to Claim 1, wherein: the guide portion of
the heel guide member projects above the transmission case
cover to be lower than a body cover as seen in a side view;
and the air intake port is opened in a side toward a r
motorcycle width center of the guide portion.
[0009]
The invention according to Claim 3 provides the power unit according to one of Claims 1 and 2, wherein the guide portion of the heel guide member hides, from outside, an air intake port of an air cleaner.
[0010]
The invention according to Claim 4 provides the power unit according to one of Claims 2 and 3, wherein: in the air passage of the heel guide member, at least one projecting strip is formed, the projecting strip covering, at a location below the air intake port and above the case air intake port, the case air intake port; and at least one

of the. at least one projecting strip forms a drain passage by extending downward beside the case air intake port. [Effect of the Invention] [0011]
In the power unit according to Claim 1, the heel guide member includes an air intake port formed in the guide portion projecting beyond the transmission case cover and an air passage which leads from the air intake port to the case air intake port and which serves also as an air duct. The heel guide member can therefore introduce the outside air for cooling the power transmission mechanism while guiding the heel of the passenger's foot placed on a pillion step. This enables a cost reduction by decreasing the numbers of components and assembly man-hours required. [0012]
In the power unit according to Claim 2, the air intake port is provided in the guide portion of the heel guide member with the guide portion projecting above the transmission case cover, and the air intake port is opened in a side toward a motorcycle width center of the guide portion. It is, therefore, possible to more effectively prevent mud and water from entering through the air intake port.
The guide portion where the air intake port- is provided is positioned lower than the body cover as seen in a side view and externally exposed. It is therefore possible to take in unheated outside air of a relatively low temperature and improve - the cooling efficiency for the

power transmission mechanism. [0013]
In the power unit according to Claim 3, the guide portion of the heel guide member hides, from outside, the air intake port of the air cleaner. It is therefore possible to prevent foreign matter, for example, mud and water from entering the air cleaner. [0014]
In the power unit according to Claim 4: the air passage of the heel guide member includes at least one projecting strip covering, at a location below the air intake port and above the case air intake port, the case air intake port; and at least one of the at least one projecting strip forms a drain passage by extending downward beside the case air intake port. Therefore, if mud or water enters the air passage of the heel guide member, it is guided into the drain passage formed, in a simple configuration, by the projecting strip provided in the air passage to be eventually discharged. It is, therefore, possible to prevent foreign matter from entering the power transmission mechanism.
[Best Mode for Carrying Out the Invention] [0015]
An embodiment of the present invention will be described below with reference to Figs. 1 to 16.
Fig. 1 is a side view of a scooter-type motorcycle according to an embodiment of the present invention.
In the following description of the embodiment, the

directions front, rear, left, and right are as seen in the forward direction of the scooter-type motorcycle 1. [0016]
A motorcycle body front portion IF and a motorcycle body rear portion IR are connected to each other via a low floor portion IC, and a motorcycle body frame making up a motorcycle body skeleton includes a downtube 3 and main pipes 4.
The downtube 3 extends downwardly from a headpipe 2 included in the motorcycle body front portion IF. The downtube 3 is bent at its lower end portion into a horizontal direction to further extend rearwardly below the floor portion IC. The left and right main pipes 4 are connected to a rear end portion of the downtube 3. The main pipes 4 extend, from where they are connected to the downtube 3, rearwardly and upwardly to be then bent at a predetermined height into a horizontal direction to further extend rearwardly. [0017]
The main pipes 4 support a fuel tank and a storage box with a seat 5 disposed' over them.
The seat 5 is longitudinal in the front-rear direction. It includes a driver seat 5f formed in a front half portion thereof and a pillion 5r formed rearward of the driver seat 5f.
The motorcycle body front portion IF includes a handlebar 6 disposed in an upper portion thereof and a front fork 7 extending in a lower portion thereof. The

handlebar 6 is journaled to the headpipe 2. A front wheel 8 is journaled to a lower end portion of the front fork 7. [0018]
A bracket 4a is projectedly provided at a lower end portion of the rearwardly upwardly extending main pipes 4. A swing-type power unit 10 is swingably linked to and supported by the bracket 4a via a link member 9.
Figs. 2, 3, and 4 show a side view, a plan view, and a front view of the power unit 10, respectively. [0019]
A single-cylinder, four-stroke internal combustion engine 30 is installed in a front portion of the power unit 10, the internal combustion engine 30 being tilted forward to such an extent that a cylinder block 32 is almost horizontally positioned. A hanger bracket 10a is forwardly projecting from a lower end portion of the portion corresponding to the crankcase of a unit case 31. An end portion of the hanger bracket 10a is linked to the link member 9 via a pivot shaft 9a (see Fig. 1). [0020]
A continuously variable belt-type transmission 35 is configured in an area ranging from the internal combustion engine 30 to an area rearward of the internal combustion engine 30. A rear wheel 21 is journaled to a speed reduction mechanism 38 provided in a rear portion of the transmission'35.
A rear cushion 22 is disposed between a rear end portion of the unit case 31 and a rear portion of the main

pipes 4. [0021]
A carbureter 24 which is connected to an inta"ke pipe 23 extending from an upper portion of a cylinder head 33 of the internal combustion engine 30 and an air cleaner 25 coupled to the carburetor 24 are disposed above the power unit 10.
A main stand 26 is pivotally attached to the hanger bracket 10a projectedly provided in a lower portion of the unit case 31 . [0022]
Referring to Fig. 1, a front portion and a rear portion of the motorcycle body front portion IF are covered by a front cover 11 and a rear cover 12, respectively; a left side and a right side of the motorcycle body front portion IF are covered by a front lower cover 13; and a central portion of the handlebar 6 is covered by a handle cover 14 .
A step plate 15 is installed in the floor portion IC. The step plate 15 includes a horizontal floor step portion 15f and a pillion step portion 15r extending, on the left and right sides, rearwardly and upwardly.
The pillion step portion 15r projects horizontally and laterally so that the passenger sitting on the pillion 5r can rest, on each side, his or her foot F (shown in dotted line in Fig, 1) on it. [0023]
A lower side cover 16 extends, below the step plate

15, alpng the edge on each side of the step plate 15.
The motorcycle body rear portion IR is connected 'to an upper portion of the pillion step portion 15r of the step plate 15. A body cover 17 covers a portion of the motorcycle body rear portion IR, the portion extending from a location forward of the main pipes 4 to left and right sides of the motorcycle body rear portion IR. An upper-end opening of the body cover 17 is openably covered by the seat 5.
[0024]
As seen in a side view, a rear fender 18 extends
rearwardly and downwardly from a rear portion of the body cover 17 thereby covering the rear wheel 21 from above, the rear portion of the body cover 17 extending rearwardly and upwardly tobegraduallythinner.
[0025]
As seen in a left side view (see Fig. 1), the rear end portions 17e, 15e, and 16e, being successively overlaid, of the body cover 17, step plate 15, and lower side cover 16 are generally inclined rearwardly. Portions around where the step plate 15 and the lower side cover 16 are fitted to each other of the rear end portions 15e and 16e project rearwardly. A horizontal portion included in the rearwardly projecting portion of the rear end portion 15e of the pillion step portion 15r is designed to be where the passenger rests the heel Fh of his or her foot F.
[0026]
An upper portion of the rearwardly projecting portion

of the, rear end portion 15e of the step plate 15 is shaped to be forwardly concave and continuous with the rear end portion 17e of the body cover 17, thereby forming a concave 19. Therefore, when the passenger rests the heel Fh of his or her foot F on the pillion step portion 15r, there is the uncovered concave 19 on the inside of the heel Fh placed on the pillion step portion 15r (see Fig. 1) .
[0027]
Fig. 5 is a cross-sectional view, taken generally
along line V - V in Fig. 2, of the power unit 10
[0028]
The unit swing case 31 includes a left unit case 31L
and a right unit case 31R which are coupled together. The right unit case 31R makes up one half part of a crankcase section. The left unit case 31L includes a crankcase section 31a which is longitudinal in the front-rear direction, a transmission case section 31b, and a reduction gear case section 31c, the three sections being located in a front portion, a center portion, and a rear portion of the left unit case 31L, respectively. [0029]
The left open side of the left unit case 31L is covered by a transmission case cover 36 which is a part of the transmission case. The continuously variable belt-type transmission 35 is housed in the left unit case 31L. The right open side of the reduction gear case section 31c located in the rear portion of the left unit case 31L is covered by the reduction gear case 37. The speed reduction

mechanism 38 is housed in the left unit case 31L. [0030]
In the so-called crankcase including the crankcase section 31a and the right unit case 31R, a crankshaft 40 is rotatably supported by left and right main bearings 41, the crankshaft 40 horizontally extending beyond the left and right main bearings 41. An AC generator 60 is provided on the right extending portion of the crankshaft 40. A cam chain drive sprocket 55 and a belt drive pulley 76 of the continuously variable belt-type transmission 3 5 are provided on the left extending portion of the crankshaft 40 [0031]
In the internal combustion engine 30, a piston 42 which reciprocates in a cylinder liner 44 of a cylinder block 32 and a crankpin 40a of the crankshaft 40 are linked by a connecting rod 4 3.
The present four-cycle internal combustion engine 30 employs a SOHC valve system. A valve mechanism 50 is provided in a cylinder head cover 34. A cam chain 51 for driving the valve mechanism 50 is wound between a cam shaft 54 and the crankshaft 40. A cam chain chamber 52 is formed through the crankcase section 31a, cylinder block 32, and cylinder head 33. [0032]
Namely, the cam chain 51 is wound, through the cam chain chamber 52, between a driven sprocket 54 fitted to a left end portion of a cam shaft 53 which is horizontally oriented in the lateral direction and the drive sprocket 55

fitted, to the crankshaft 40.
A spark plug 45 is fitted into the cylinder head 33 diagonally from the opposite side to the cam chain chamber 52 (from the right side) toward a combustion chamber.
[0033]
The valve mechanism 50 is provided inside the
cylinder head cover 34 as shown in Fig, 6. With the cylinder largely inclined forwardly into a nearly horizontal position, an intake valve 56 and an exhaust valve 57 are provided above and below the cam shaft 53, respectively. A rocker arm 59i and a rocker arm 59e are rockably fitted to an upper rocker shaft 58i and a lower rocker arm 58e, respectively. As the cam attached to the cam shaft 53 turns, the rocker arms 59i and 59e are rocked to open and close the intake valve 56 and the exhaust valve 57 at predetermined timing.
[0034]
The AC generator 60 is provided on the right side
surface of the right unit case 31R. A bowl-shaped outer rotor 62 is fixed, via an ACG boss 61, to an end portion of the crankshaft 4 0 projecting from a central cylindrical portion 31d of the right unit case 31R. A magnet 63 is circumferentially disposed along the inner circumference of the outer rotor 62. Inside the magnet 63, a stator 64 around which a stator coil 65 is wound is fixed to the central cylindrical portion 31d. [0035]■ . . '
A forced-cooling fan 66 is attached on the right side

face of the outer rotor 62. The side of the fan 66 is covered by a"fan cover 67. A shroud 68 surroundingly covering the cylinder block 32 and cylinder head 33 is provided continuously with the fan cover 57. [0036]
In the crankcase section 31a of the unit swing case 31, the cam chain chamber 52 is formed being separated from the crankcase by the main bearing 41. The left side wall of the cam chain chamber 52 forms a separation wall 71 which separates the continuously variable belt-type transmission chamber 70 to the left of the separation wall 71 from the cam chain chamber 52. A circular through hole 71a, through which the crankshaft 40 extends, is formed through the separation wall 71, the through hole 71a having a flat cylindrical shape with a large diameter. An annular sealing member 72 is press-fitted in the through hole 71a. The crankshaft 40 extends through the hollow portion of the annular sealing member 7 2. [0037]
The drive sprocket 55 is fitted in a portion between the sealing member 72 and the main bearing 41 of the crankshaft 40. The cam chain 51 is wound on the drive sprocket 55.
The sealing member 72 watertightly separates the continuously variable belt-type transmission chamber 7 0 and the cam chain chamber 52, so that oil leakage from the latter to the former is prevented.
A belt drive pulley 76 is rotatably provided on the

ciranks'haft 4 0 extending through the sealing member 7 2. [0038]
The belt drive pulley 76 includes a fixed pulley half 7 7 and a movable pulley half 78. The fixed pulley half 77 is fixed, via a boss 79, to a left end portion of the crankshaft 40. The movable pulley half 78 is spline-fitted, on the right of the fixed pulley half 77, to the crankshaft 40. The movable pulley half 78 rotates together with the crankshaft 40. While rotating, the movable pulley half 78 can axially slide toward or away from the fixed pulley half 77. A V-belt 75 is rotatably held between the fixed pulley half 77 and the movable pulley half 78. [0039]
A cam plate 80 is fixedly provided, closely to the annular sealing member 72, to the right of the movable pulley half 78. A slide piece 80a provided in an outer peripheral end portion of the cam plate 80 is slidably engaged with a cam plate sliding boss portion 78a axially formed in an outer peripheral end portion of the movable pulley half 78.
The side surface on the cam plate 80 side of the movable pulley half 78 is tapered toward the cam plate 80. A dry weight roller 81 is accommoda'ted on the inner side of the tapered surface, that is, between the tapered surface and the cam plate 80. [0040]
When the rotation speed of the crankshaft 40 increases, the dry weight roller 81 also rotating between

the mO'Vable pulley half 78 and the cam plate 80 is centrifugally moved in the centrifugal direction to push and move the movable pulley half 78 leftward closer to the fixed pulley half 77. As a result, the V-belt 75 held between the pulley halves 77 and 78 is moved in the centrifugal direction to increase the winding diameter. [0041]
A belt-driven pulley 86 corresponding to the belt-drive pulley 76 is disposed rearward of the belt drive pulley 76 and includes a fixed pulley half 87 and a movable pulley half 88. The fixed pulley half 87 is fitted to ah inner sleeve 89 which is supported to be rotatable relative to a speed reducer input shaft 92 of the speed reduction mechanism 38. The movable pulley half 88 is fitted to an outer sleeve 90 which is axially movably supported, to the left of the fixed pulley half 87, by the inner sleeve 8 9.
The V-belt 75 is held between the pulley halves 87 and 88. [0042]
A centrifugal clutch 91 is provided on the left side of the speed reducer input shaft 92 and inner sleeve 89, When the rotation speed of the inner sleeve 89 increases, the centrifugal clutch 91 engages to transmit the power transmitted to the inner sleeve 89 via the V-belt 7 5 to the speed reducer input shaft 92.
In the speed reduction mechanism 38, the power transmitted to the speed reducer input shaft 92 is transmitted to an output shaft 94 via an intermediate shaft

93, that iS/ the rotation of the input shaft 92 is transmitted to the output shaft 94 after deceleration by means of a gear engagement. The output shaft 94 makes up a rear wheel shaft to rotate the rear wheel 21.
[0043]
Referring to Fig. 5, a transmission case cover 36
covering the continuously variable belt-type transmission chamber 70 from the left side covers a portion of the continuously variable beIt-type transmission chamber 7 0 extending from the belt-drive pulley 76 on the front side to the centrifugal clutch 91 on the rear side. A kick shaft 27 is rotatably inserted through and supported at a portion slightly forward of a middle portion of the transmission case cover 36, A drive helical gear 100 is fitted to an inner end portion of the kick shaft 27. The drive helical gear 100 is biased by a return spring 101. [0044]
A sliding shaft 102 is supported at a front inner portion of the transmission case cover 36 coaxially with the crankshaft 4 0, rotatably, and axially slidably. A driven helical gear 103 is formed on the sliding shaft 102 and is engaged with the drive helical gear 100. A ratchet wheel 104 is fixed to a right end portion of the driven helical gear 103. These parts as a whole are biased leftward by a friction spring 105.
On the boss 79 on the crankshaft 40 side, a ratchet 7 9a opposing the ratchet wheel 104 is formed. They can be brought into or out of contact with each other by sliding

t'he sliding shaft 102
[0045]
When a kick pedal is pressed down and the kick shaft
27 rotates opposing the return spring 101, the drive helical gear 100 rotates integrally with the kick shaft 27, This causes the driven helical gear 103 engaged with the drive helical gear 100 to rotate integrally with the sliding shaft 102 and slide rightward opposing the friction spring 105. As a result, the ratchet wheel 104 engages the ratchet 79a formed on the boss 79, and the crankshaft 40 is forcedly rotated to start the internal combustion engine 30
[0046]
In the present internal combustion engine, a starter
motor 110 is disposed above the crankcase section 31a of the left unit case 31L. As shown in Fig. 7, the starter motor 110 includes a leftwardly projecting pinion .113 around which an inner rotor coil 112 surrounded by an outer Stator magnet 111 is wound. A gear 113a is formed at an end portion of the pinion 113.
[0047]
A jump gear mechanism 115 held between the crankcase
section 31a and the transmission case cover 36 is positioned between the starter motor 110 and the belt-drive pulley 76 with its shaft laterally horizontally oriented. The pinion gear 113a of the starter motor 110 is engaged with an input gear 116 disposed to the right of the jump gear mechanism 115. A left jump gear 117 is disposed to the left of the jump'gear mechanism 115. When the left jump

gear 1.17 jumps out leftward, it engages a starter ring gear 77a formed on an outer peripheral edge of the fixed pulley half 77. [0048]
Therefore, when the starter motor 110 is started, the rotation of the pinion 113 is transmitted to the input gear
116 of the jump gear mechanism 115, causing the jump gear
117 to jump out leftward and engage the starter ring gear 77a of the fixed pulley half 77. As a result, the fixed pulley half 77 rotates together with the crankshaft 40 to start the internal combustion engine 30.
When the starter motor 110 stops, the j ump gear 117 retracts to be disengaged from the starter ring gear 77a. [0049]
The fixed pulley half 77 on which the starter ring gear 77a to be engaged with the jump gear 117 is formed has a cooling fan 118 made of iron and bolted (not shown) to its side (left side) opposite to the side where the V-belt 75 is held. The cooling fan 118 operates to take in the outside air for cooling the continuously variable belt-type transmission 35. [0050]
The transmission case cover 36 includes a side wall and a peripheral wall, the former covering a left side portion and the latter surrounding an outer peripheral portion, respectively, of the continuously variable belt-type transmission 35. As shown in Fig. 8, the side wall includes, in a front portion thereof, a concave wall

portion 36a which is continuous, via a step 36b, with the remaining portion of the side wall. The concave wall portion 36a has a c-ase air intake port 36c which, facing leftward, has a deformed rectangular shape.
As shown in broken line in Fig. 8, a cylindrical case air exhaust duct 36d is formed to extend, in an approximately central portion in the front-rear direction of the side wall, in a diagonal upward-downward direction along the inner surface of the side wall. The upper end of the exhaust duct 36d is opened to the chamber interior. The lower end is opened to the outside. [0051]
Hence, the case air intake port 36c in a front portion of the transmission case cover 36 is opened toward the cooling fan 118 heat-bonded to the fixed pulley half 77 (see Fig. 5). The rotation of the cooling fan 118 can take cooling air into the continuously variable belt-type transmission chamber 70 through the case air intake port 35c. The cooling air having cooled the continuously variable belt-type transmission 35 can be exhausted to the outside through the case air exhaust duct 36d. [0052]
A support 36e to support the jump gear 117 is formed in an upper portion of the concave wall portion 36a provided in a front portion of the transmission case cover 36, the support 36e having a partially circular conic shape Bolt holes 36i and 36j are formed above and below the case air intake port 36c, respectively.

A heel guide member 150 serving also as an air intake duct is fitted to the concave wall portion 36a provided in a front portion of the transmission case cover 36.
An inner wall member 151-and an outer wall cover member 161 of the heel guide member 150 are united to form an air intake duct which internally provides air passage space. [0054]
As shown in Figs. 9 to 11, the inner wall member 151 includes an inner wall 152 which is shaped like a pectoral fin of a fish as seen in a side view (see Figs. 9 and 10). The inner wall 152 includes an upper wall portion 152u, a lower wall portion 1521, and a slanted wall portion 152s, the three wall portions being vertical as seen in a front view and shaping the inner wall 152 such that the upper wall portion 152u and the lower wall portion 1521 being laterally shifted from each other are linked by the slanted wall portion 152s (see Fig. 11).
A peripheral wall 153 is projectedly formed on the left side surface of the inner wall 152 to be slightly inside the peripheral edge of the inner wall 152 (see Fig. 9) . [0055]
The upper wall portion 152u of the inner wall 152 includes an air intake port 154 formed inside the peripheral wall 153. A louver 155 is installed over the air intake port 154.

In the lower wall portion 1521 of the inner wall 152, a connection port 152c corresponding to the case air intake port 3 6c formed in the concave wall portion 3 6a is formed.
In the slanted wall portion 152s, a circular conic portion 152e corresponding to the circular conic support 36e formed on the transmission case cover 36 is formed. [0056]
On the left side surface of the inner wall 152, a projecting strip is projectedly formed to extend curvedly forwardly and downwardly from above the connection port 152c along a front side of the connection port 152c. A front lower portion of the projecting strip 156 extends downwardly in parallel with a front side portion of the peripheral wall 153, forming a drain passage 170 between them.
The drain passage 170 has an open lower end. [0057]
A linear projecting strip 157 is projectedly formed upward of the projecting strip 156 and downward of the air intake port 154.
The projecting strip 157 extends, below the air intake port 154, forwardly and slightly downwardly from a rear edge portion of the peripheral wall 153. A rear portion of the lower projecting strip 156 is positioned below a front portion of the upper projecting strip 157, forming an air passage 160 between them. [0058]
A cutout 153b is formed at a location downward of a

rear end portion of the projecting strip 156, the location being in a slanted rear edge portion of the peripheral wall 153. A fixing hole 158i is formed in an upper end portion of the portion below the cutout 153b of the peripheral wall 153. .A projecting strip 153a extends forwardly and upwardly from the fixing hole 158i.
The fixing hole 158i is located above the connection port 152c and corresponds to the bolt hole 36i formed in the transmission case cover 36. A fixing hole 158j corresponding to the bolt hole 36j is formed below the connection port 152c. [0059]
A catching projection 159p is projectedly formed on a rear edge portion, which is more rearwardly positioned than the air intake port 154, of the upper wall portion 152u of the inner wall 152. Another catching projection 159q is projectedly formed on a curved lower front edge portion of the lower wall portion 1521. [0060]
As shown in Figs. 12 to 14, the outer wall cover member 161 includes an outer wall 162 which is shaped approximately the same as the inner wall 152 of the inner wall member 151 as seen in a side view (see Figs. 12 and 13). The outer wall 162 includes an upper wall portion 162u, a lower wall portion 1621, and a slanted wall portion 162s, the three wall portions being vertical as seen in a front view and shaping the outer wall 162 such that the upper wall portion 162u and the lower wall portion 1621 being

I'aterally shifted from each other are linked by the slanted wall portion 162s (see Fig. 14).
A peripheral wall 163 slightly larger than the peripheral wall 153 of the inner wall member 151 is projectedly formed on the right side surface of and along the peripheral edge of the outer wall 162 (see Fig. 13). [0061]
A projecting strip 166 is projectedly formed on the right side surface of the outer wall 162, the projecting strip 166 being shaped to fit the upper side of the projecting strip 156 curvedly formed on the left side surface of the inner wall 152. Thus, the drain passage 170 is also formed between the projecting strip 166 and the peripheral wall 163.
A projecting strip 167 is projectedly formed upward of the projecting strip 166, the projecting strip 167 being shaped to fit the upper side of the linear projecting strip 157 formed on the left side surface of the inner wall 152. [0062]
Fixing holes 168i and 168j corresponding to the fixing holes 158i and 158j are formed in a middle portion and a lower end portion of the rear slanted portion of the peripheral wall 163.
Catching pieces 169p and 169q corresponding to the catching projections 159p and 159q are formed in an upper rear edge portion and a lower front edge portion, respectively, of the peripheral wall 163.
The catching piece 169p is shaped like a hook to

catch -and engage the catching projection 159p. The catching piece 169q has a hole into which the catching projection 159 is inserted for engagement. [0063]
The inner wall member 151 and the outer wall cover member 161 are joined together by aligning the inner wall 152 and the outer wall 162 such that they face each other and fitting the peripheral wall 163 of the outer wall cover member 161 around the outer periphery of the peripheral wall 153 of the inner wall member 151. In doing this, first, the catching projection 159q of the inner wall member 151 is inserted into the catching piece 169q of the outer wall cover member 161 thereby engaging the two parts, and then the inner wall member 151 and the outer wall cover member 161 are joined together by fitting the peripheral wall 153 and the peripheral wall 163 to each other. When this is done, the catching projection 159p of the inner wall member 151 is caught by the catching piece 169p of the outer wall cover member 161. As a result, the inner wall member 151 and the outer wall cover member 161 are united into an air intake duct, i.e. the heel guide member 150. [0064]
Inside the heel guide member (the air intake duct) 150, an air passage 160 is formed by the linear upper projecting strips 157 and 167 and the curved lower projecting strips 156 and 166. The air passage 160 has a labyrinth structure and leads from the air intake port 154 formed in an upper portion of the inner wall 152 to the

c'onnection port 152c formed in a lower portion of the inner wall 152.
If mud or water enters the air passage 160 through the air intake port 154, the mud or water flows forward over the upper surfaces of the inclined upper projecting strips 157 and 167, drops from the front ends of the inclined upper projecting strips 157 and 167 onto the lower projecting strips 156 and 166. The mud or water then further flows forward over the curved projecting strips 156 and 166, that is, down through the drain passage 170 to be subsequently discharged to the outside. [0065]
The heel guide member 150 is fitted to the concave wall portion 36a formed in a front portion of the transmission case cover 36.
In doing this, the lower wall portions 1521 and 1621 and slanted wall portions 152s and 162s of the heel guide member 150 are fitted to the concave wall portion 36a, and the mutually fitted fixing holes 158i and 168i and the mutually fitted fixing holes 158j and 168j are fitted to the corresponding bolt holes 36i and 36j, respectively, formed in the transmission case cover 36. Bolts 171 and 172 are then inserted through the corresponding fixing holes and bolt holes thus fitted together and tightened to fix the heel guide member 150 to the transmission case cover 36 [0066]
When the heel guide member 150 has been fixed to the transmission case cover 36, the outer surface of the outer

wall cover member 161 is coplanar with the outer surface of the transmission case cover 36, and the connection port 152c formed in a lower portion of the inner wall member 151 is connected to the case air intake port 36c formed in the transmission case cover 36. [0067]
The upper wall portions 152u and 162u of the heel guide member 150 are upwardly projecting above the transmission case cover 36 while curving toward the motorcycle inside. The air intake portion 154 formed in the upper wall portion 152u of the inner wall member 151 is rightwardly (toward the motorcycle inside) open,
The louver 155 provided at the air intake port 154 faces the right (the motorcycle inside) with its blades inclined rightwardly (toward the motorcycle inside) and downwardly not to easily allow mud or water to enter the air intake port 154 from above. [0068]
As described above, the heel guide member 15 0 to serve also as an air intake duct is attached to a front portion of the transmission case cover 36. Therefore, when the cooling fan 118 attached to the fixed pulley half 77 of the continuously variable belt-type transmission 35 rotates, the outside air is introduced, as a cooling air, from the air intake port 154 of the heel guide member 150 into the continuously variable beIt-type transmission chamber 7 0 via the air passage 160 and the case air intake port 36c, and the cooling air having cooled the continuously variable

belt-type transmission 35 is exhausted from the case air
exhaust duct 36d to the outside.
[0069]
If foreign matter such as mud or water enters the air passage 160 through the air intake port 154, the foreign matter is discharged to the outside through the drain passage 170 formed by the projecting strips 157 and 167 and the projecting strips 156 and 166, so that foreign matter is prevented from entering the continuously variable belt-type transmission 7 0. [0070]
The upper wall portions 152u and 162u projecting above the transmission case cover 36 of the heel guide member 150 make up a guide portion 150u. As shown in Fig. 1, the guide portion 150u is partly overlapped, as seen in a side view, by a rear end portion of the pillion step portion 15r of the step plate 15 and extends upward covering the concave 19 formed above the overlapped portion.
The heel portion Fh of the passenger's foot F (shown in two-dot chain line in Fig. 1) placed on the pillion step portion 15r is guided in place by the guide portion 150u closing the concave 19 from an inner side of the motorcycle. [0071]
In the air cleaner 25 disposed upward of the crankcase section of the internal combustion engine 30, a rear portion of a container 25a is laterally bulging to both sides, and an intake duct 25b extends forward from the left bulging portion along the left wall of the container

2'5a.
A cleaner air intake port 25i which is opened at a front end of the intake duct 25b is inwardly separated from the guide portion 150u of the heel guide member 150 (see Figs. 3 and 4) and overlaps with the guide portion 150u as seen in a side view (see Fig. 2). [0072]
Thus, with the guide portion 150u of the heel guide member 150 covering, from outside, the cleaner air intake port 25i of the air cleaner 25, foreign matter, for example, mud or water is prevented from entering the air cleaner 25. [0073]
The shroud 68 covering the periphery of the cylinder block 32 and cylinder head 33 of the internal combustion engine 30 has a rectangular opening in its front end portion and, as shown in Figs. 2 to 5, the cylinder head cover 34 is fitted through and projecting forward from the rectangular opening. An upper wall 68u, a lower wall 68d, and a left wall 681 extend rearward from the rectangular opening along the sides of the cylinder head 33 and cylinder block 32. The right wall 68r largely bulges rightward to be increasingly separated from the cylinder head 33 and cylinder block 32 until being connected to the fan cover 67. [0074]
The fan cover 67 includes an annular frame 67a whose central axis is the crankshaft 40. A front periphera-1 portion of the annular frame 67a is screwed, with a screw

120, to a rear end portion of the right wall 68r of the shroud 68. The portion other than the front peripheral portion of the annular frame 67a is fixedly bolted, with a bolt 121, to a right edge portion of the right unit case 31R. The fan cover 67 is regarded as an extension member of the shroud 68, and a cooling air intake port 67i is provided, facing the forced-cooling fan 66, in the right wall (see Fig, 5) . [0075]
A cooling air outlet port 68e is opened in a rear lower-half portion of the left wall 681 of the shroud 68 with a front end portion of the air exhaust duct 69 connected to the cooling air outlet port 68e.
The air exhaust duct 69 extends leftward from the cooling air outlet port 68e provided in the left wall 681 and then curves rearwardly and downwardly to further extend, being partly fitted to the concave wall portion 36a of the transmission case cover 36, along the lower end surface of the heel guide member 150 until reaching the step 36b of the transmission case cover 36 where a rear-end air exhaust port 69e is opened rearwardly and downwardly (see Figs. 2, 3, and 4) . [0076]
The shroud 68 surroundingly -covering the cylinder block 32 and cylinder head 33 includes the cooling air intake port 67i provided in the fan cover 67 that is a rearward extension of the right wall 68r and the cooling air outlet port 68e formed in the left wall 681 opposing

the right wall 68r. Therefore, as seen in Fig. 5, the cooling air sucked in from the cooling air intake port 67i by the rotation of the forced-cooling fan 66 flows, while being diagonally forwardly guided by the curved right wall 68r, leftward passing around the peripheral portions of the cylinder block 32 and cylinder head 33, thereby cooling the cylinder block 32 and cylinder head 33. The cooling air having cooled the cylinder block 32 and cylinder head 33 flows out of the cooling air outlet port 68e provided in the left wall 681 without changing the flow direction. [0077]
Thus, the cooling air flows evenly and smoothly, without becoming locally stagnant, through the inside of the shroud 68 unidirectionally from the cooling air intake' port 67i to the cooling air outlet port 68e before being let out from the air exhaust duct 69. The cooling air can, therefore, cool the portions to be cooled of the cylinder block 32 and cylinder head 33 of the internal combustion engine 30 thoroughly and efficiently. Furthermore, with the passage resistance being small and the cooling air volume being large, a great cooling effect can be expected. [0078]
Referring to the side view shown in Fig. 2 of the power unit 10, the air exhaust duct 69 is located below the cylinder axis C -- C that is the central axis of the cylinder bore of the cylinder block 32.
Referring to the front view shown in Fig. 4 of the power unit 10, the air exhaust duct 69 is located, in the

motorcycle width direction, approximately outside (to the right of, as seen in Fig. -4) the air cleaner 25 and inside (to the left of, as seen in Fig. 4) the outer surface of the transmission case cover 36. [0079]
Thus, the air exhaust duct 69 is small and can be compactly installed on the left of the shroud 68 to extend along the lower end surface of the heel guide member 150. This makes the air exhaust duct 69 less conspicuous resulting in better appearance. [0080]
The cleaner air intake port 25i of the air cleaner 25 and the air intake port 154 of the heel guide member (air intake duct) 150 are both located higher than the cylinder axis C -- C as seen in a side view (see Fig. 2). [0081]
Namely, whereas the air exhaust port 69e of the air exhaust duct 69 is located below the cylinder axis C -- C, the cleaner air intake port 25i and the air intake port 154 are located higher than the cylinder axis C -- C. Moreover, the heel guide member 150 and the transmission case cover 3 5 exist between them.
Therefore, the warm exhaust air coming out of the air exhaust port 69e below the heel guide member 150 mostly flows rearward along the lower surface of the transmission case cover 36. If part of the exhaust air flows upward along the side surface of the transmission case cover 36, it is unlikely to be sucked into the cleaner air intake

port 25i or the air intake port 154. This can prevent the intake air temperature from rising and the cooling efficiency for the continuously variable beIt-type transmission 35 from lowering. [0082]
The air intake port 154 is located, in the motorcycle width direction, between the cleaner air intake port 25i and the air exhaust port 69e of the air exhaust duct 69 (see Fig, 4),
Therefore, if the engine cooling air exhausted from the air exhaust port 69e flows upward, for example, when the motorcycle is stopped, the exhaust air is likely to be led to the nearer air intake port 154 before reaching the farther cleaner air intake port 25i, so that the exhaust air is quite unlikely to be sucked into the farther cleaner air intake port 25i. This can prevent the intake air temperature from rising. [0083]
Furthermore, the heel guide member (air intake duct) 150 and the cleaner air intake port 25i are located to overlap with each other as seen in a side view, so that the guide portion 150u serves as an external guide to securely prevent the engine cooling air exhausted from the air exhaust port 59e from being sucked into the cleaner air intake port 25i. This makes it more possible to prevent the intake air temperature from rising and foreign matter, for example, mud or water from entering through the cleaner air intake port.

As described above, the heel guide member 150 is configured to serve also as an air intake duct. Namely, it can introduce the outside air for cooling the continuously variable belt-type transmission 35, whereas the guide portion 150u positioned to close, from inside in the motorcycle width direction, the concave 19 formed in a left rear-end portion of the motorcycle body covers 15 and 17 guides the heel Fh of the passenger's foot F in place on the pillion step portion 15r. This enables a cost reduction by decreasing the numbers of components and assembly man-hours required.
[0085]
The air intake port 154 is formed in a portion, which
projects above where the heel guide member 150 is attached to the transmission case cover 36, of the guide portion 150u. Moreover, the air intake port 154 is opened in a side toward the motorcycle width center of the guide portion 150u. It is, therefore, possible to more effectively prevent mud and water from entering through the air intake port 154.
[0086]
The guide portion 150u including the air intake port
154 is located, as seen in a side view (see Fig. 1), in the concave 19 formed below the body cover 17 and externally exposed. It is, therefore, possible to take in unheated outside air of a relatively low temperature. This can
improve the cooling efficiency for the continuously

variable belt-type transmission 35. [0087]
In the. air passage 160 of the heel guide member 150, the proje.cting strips 156, 166, 157, and 167 are formed, the projecting, strips covering, at locations below the air intake port 154 and above the case air intake port 36c, the case air intake port 35c. The projecting strips 156 and 166 extend downward beside the case air intake port, thereby forming the drain passage 170. If mud or water enters the air passage 170 of the heel guide member 150, it is guided into the drain passage 160 formed, in a simple configuration, by the projecting strips 156 and 166 provided in the air passage 160 to be eventually discharged Thus, it is possible to effectively prevent foreign matter from entering the continuously variable belt-type transmission chamber 7 0. [Brief Description of the Drawings] [0088]
[Fig. 1] is an overall side view of a scooter-type motorcycle according to an embodiment of the present invention.
[Fig. 2] is a side view of a power unit of the scooter-type motorcycle.
[Fig. 3] is a plan view of the power unit of the scooter-type motorcycle.
[Fig. 4] is a front view of the power unit of the scooter-type motorcycle.
[Fig. 5] is a cross-sectional view taken along line V

-'- V in Fig. 2 .
[Fig. 6] is a cross-sectional view taken along line
VI -- VI in Fig. 5.
[Fig. 7] is a cross-sectional view taken along line
VII -- VII in Fig. 2.
[Fig. 8] is a side view of a transmission case cover
[Fig. 9] is a left side view of an inner wall member of a heel guide member.
[Fig. 10] is a right side view of the inner wall member of the heel guide member.
[Fig. 11] is a cross-sectional view taken along line VII — VII in Fig. 10.
[Fig. 12] is a left side view of an outer wall cover member of the heel guide member.
[Fig. 13] is a right side view of the outer wall member of the heel guide member.
[Fig. 14] is a cross-sectional view taken along line
XIV — XIV in Fig. 13.
[Fig. 15] is a right side view of the heel guide member wherein the inner wall member and the outer wall cover member are united.
[Fig. 16] is a cross-sectional view taken along line
XV -- XV in Fig. 15.
[Description of Reference Numerals] [0089]
10... Power unit 15... Step plate 15r... Pillion step portion

, 17. . . Body cover 19... Concave 25... Air cleaner 251... Cleaner air intake port 30... Internal combustion engine 31... Unit case 36... Transmission case cover 36c... Case air intake port 36d... Case air exhaust duct 118... Cooling fan 119... Exhaust duct
150... Heel guide member (Air intake duct) 150u... Guide portion 151... Inner wall member 152... Inner wall 153... Peripheral wall 154... Air intake port 155... Louver 156... Projecting strip 157... Projecting strip 160... Air passage 161... Outer wall cover member 162... Outer wall 163... Peripheral wall 166... Projecting strip 167.., Projecting strip 170.-. Drain passage

[Docuinent Name] Scope of Claims [Claim 1]
A swing-type power unit of a motorcycle, comprising an internal combustion engine, a power transmission mechanism rearwardly extending from the internal combustion engine, and a rear wheel journaled to a rear portion of the power transmission mechanism which are unitedly and swingably supported by a motorcycle body frame,
wherein: a pillion step is projectedly provided on a side of a motorcycle body;
a heel guide member is attached, overlappingly from a side, to a front portion of a transmission case cover which covers a side of the power transmission mechanism;
a projecting guide portion of the heel guide member is provided on an inner side, in a motorcycle width direction, of and closely to the pillion step;
a case air intake port is formed in a front portion of the transmission case cover being overlapped by the heel guide member; and
in the heel guide member, an air intake port is formed in the guide portion projecting beyond the transmission case cover, and an air passage leading from the air intake port to the case air intake port is formed. [Claim 2]
The power unit according to Claim 1,
wherein: the guide portion of the heel guide member projects above the transmission case cover to be lower than a body cover as seen in a side view; and

'the air intake port is opened in a side toward a
motorcycle width center of the guide portion.
[Claim "3]
The power unit according to one of Claims 1 and 2, wherein the guide portion of the heel guide member
hides, from outside, an air intake port of an air cleaner.
[Claim 4]
The power unit according to one of Claims 2 and 3^ wherein: in the air passage of the heel guide member,
at least one projecting strip is formed, the projecting
strip covering, at a location below the air intake port and
above the case air intake port, the case air intake port;
and
at least one of the at least one projecting strip
forms a drain passage by extending downward beside the case
air intake port.

Documents:

351-CHE-2008 AMENDED PAGES OF SPECIFICATION 26-12-2011.pdf

351-CHE-2008 AMENDED CLAIMS 26-12-2011.pdf

351-CHE-2008 FORM-3 26-12-2011.pdf

351-CHE-2008 OTHER PATENT DOCUMENT 26-12-2011.pdf

351-CHE-2008 POWER OF ATTORNEY 26-12-2011.pdf

351-CHE-2008 EXAMINATION REPORT REPLY RECEIVED 26-12-2011.pdf

351-che-2008-abstract.pdf

351-che-2008-claims.pdf

351-che-2008-correspondnece-others.pdf

351-che-2008-description(complete).pdf

351-che-2008-drawings.pdf

351-che-2008-form 1.pdf

351-che-2008-form 18.pdf

351-che-2008-form 26.pdf

351-che-2008-form 3.pdf

351-che-2008-form 5.pdf

abs-351-che-2008.jpg

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Patent Number

250729

Indian Patent Application Number

351/CHE/2008

PG Journal Number

04/2012

Publication Date

27-Jan-2012

Grant Date

23-Jan-2012

Date of Filing

11-Feb-2008

Name of Patentee

HONDA MOTOR CO., LTD.

Applicant Address

1-1, MINAMIAOYAMA 2-CHOME MINATO-KU, TOKYO

Inventors:

#	Inventor's Name	Inventor's Address
1	TSUCHIYA, RYUJI	C/O HONDA R&D CO LTD 4-1, CHUO 1-CHOME WAKO-SHI, SAITAMA 351-0193
2	FUNAYAMA, YOSHIHIRO	C/O HONDA R&D CO LTD 4-1, CHUO 1-CHOME WAKO-SHI, SAITAMA 351-0193
3	ODAGIRI, HIROSHI	C/O HONDA R&D CO LTD 4-1, CHUO 1-CHOME WAKO-SHI, SAITAMA 351-0193

PCT International Classification Number

B62J13/00

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	2007-032761	2007-02-13	Japan