Title of Invention	STARTER-MOTOR ARRANGEMENT STRUCTURE OF INTERNAL COMBUSTION ENGINE
Abstract	To provide a starter-motor arrangement structure which can make compact as a whole an internal combustion engine having a tensioning device for a roller chain, without increasing the size of the internal combustion engine. [Solution] In the starter-motor arrangement structure of the internal combustion engine, in which an endless roller chain 43 is wound between a drive sprocket 32 fitted on a crankshaft and a driven sprocket 42 fitted on a cam shaft, a push rod 56 in pressing contact with a pressing member 51 pushing the roller chain 43 is disposed such that a rod axis Lr thereof forms an obtuse angle on a front side in side view with a cylinder axis Lc of a cylinder 23 standing from a crankcase 22, and a starter motor 70 is disposed in a front portion of the crankcase 22 within the front-side obtuse angle formed between the cylinder axis Lc and the rod axis Lr. [Selected Drawing] Fig. 5

Title of Invention

STARTER-MOTOR ARRANGEMENT STRUCTURE OF INTERNAL COMBUSTION ENGINE

Abstract

To provide a starter-motor arrangement structure which can make compact as a whole an internal combustion engine having a tensioning device for a roller chain, without increasing the size of the internal combustion engine. [Solution] In the starter-motor arrangement structure of the internal combustion engine, in which an endless roller chain 43 is wound between a drive sprocket 32 fitted on a crankshaft and a driven sprocket 42 fitted on a cam shaft, a push rod 56 in pressing contact with a pressing member 51 pushing the roller chain 43 is disposed such that a rod axis Lr thereof forms an obtuse angle on a front side in side view with a cylinder axis Lc of a cylinder 23 standing from a crankcase 22, and a starter motor 70 is disposed in a front portion of the crankcase 22 within the front-side obtuse angle formed between the cylinder axis Lc and the rod axis Lr. [Selected Drawing] Fig. 5

Full Text	[Document Name] Specification [Title of the Invention] STARTER-MOTOR ARRANGEMENT STRUCTURE OF INTERNAL COMBUSTION ENGINE [Technical Field] [0001] The present invention relates to a structure iof arranging a starter motor in an internal combustion engine having a cam-chain tensioning device consisting of \| a pushing means pushing a roller chain transmitting power to a valve system and a push rod in pressing contact iwith the pushing means. [Background Art] [0002] In a case where a roller chain is employed ais a cam chain, the friction becomes less than the case ofia silent chain. However, the former case requires equipments occupying a large space such as a pushing means and a push rod, making it difficult to dispose a starter motbr without increasing the size of an internal combustion engine. An example of such an internal combustion engine employing the roller chain and having a cam-chaini tensioning device such as the pushing means and the push rod is disclosed in Patent Literature 1. [Citation List] [Patent Literature] [0003] I [Patent Literature 1] JP Patent No. 4035226 [0004] The internal combustion engine disclosed in Plitent Literature 1 is such that a cylinder extends frontward from a crankcase substantially horizontally, and thus a iroller chain is disposed to extend frontward from a crankshaft. A tensioner arm as a pushing means and a pushj rod of a cam-chain tensioning device are disposed to intetsect the roller chain extending horizontally in a front-rea\|: direction, in side view. [Summary of Invention] [Technical Problem] [0005] A starter motor disposed around a starter driven gear that has a large diameter and is fitted on the crankshaft is disposed at a position obliquely above and on tihe rear side of the crankshaft, which is other than wherejmembers including the roller chain extending frontward ofithe crankshaft (starter driven gear) and an oil colletiting chamber above the crankshaft. Since the roller chain extends frontward ofithe crankshaft and the starter motor protrudes obliquely above and on the rear side of the crankshaft, the size of the internal combustion engine including the starter (motor is inevitably large. ] [0006] The present invention has been developed inj view of the foregoing, and an object thereof is to provide a starter-motor arrangement structure that preventi the size of an internal combustion engine having a rollerj-chain tensioning device from becoming large, and can make:such an internal combustion engine compact as a whole. [Solution to Problem] [0007] To attain the above object, an arrangement of the invention according to claim 1 provides a starter-motor arrangement structure of an internal combustion engjine in which: a crankshaft is rotatably journaled to a crnkcase of the internal combustion engine installed on a mdtorcycle such that the crankshaft is oriented in a left-right direction, an endless roller chain is wound betweeili a drive sprocket fitted on the crankshaft and a driven sprcket fitted on a cam shaft of a valve system, the roller chain is pushed by a pressing member; and the pressing member is in pressing contact with a push rod inserted and sjlidably fitted in a guide bore formed in the crankcase, wherein the push rod is disposed such that a rod axis thereof forms an obtuse angle on a front side in a side view with a cylinder axis of a cylinder standing on the crankGase, and wherein the starter motor is disposed in a front 5)ortion of the crankcase within the obtuse angle formed between the cylinder axis and the rod axis. [0008] An arrangement of the invention according t starter motor. [0009] An arrangement of the invention according to claim 3 provides the starter-motor arrangement structure of, the internal combustion engine according to claim 1 or ;2, wherein a starter drive gear is disposed on a startjer drive shaft protruding leftward from a motor main body of the starter motor, wherein a starter driven gear is rotatably journaled to a left shaft portion of the crankshaft, and wherein an intermediate gear having a large-diameter gear and a small-diameter gear that are integrally formjed is interposed between and in meshing engagement with the starter drive gear and the starter driven gear. [0010] An arrangement of the invention according td claim 4 provides the starter-motor arrangement structure of the internal combustion engine according to claim 3, yrherein the oil pump is disposed at a position to overlap with the starter driven gear in a side view on a right side of a vertical plane including the cylinder axis. [0011] An arrangement of the invention according to claim 5 provides the starter-motor arrangement structure! of the internal combustion engine according to any one bf claims 1 through 4, wherein a mount plate supporting the internal combustion engine on a vehicle-body frame covers the starter motor that is disposed in a front portion of the crankcase from a front side, and wherein the moiint plate expands at a portion which corresponds to a power terminal protruding on the starter motor. [Advantageous Effect of Invention] [0012] According to the starter-motor arrangement structure of the internal combustion engine of claim 1, the jstarter motor is disposed within the obtuse angle facing frontward formed in the side view between the cylinder axis iof the cylinder standing from the crankcase (a central ajis of a cylinder bore) and the rod axis of the push rod (a central axis of a guide bore in which the push rod is insejrted and slidably fitted). Therefore, by locating the stajrter motor, which is disposed in the front portion of the craiikcase, at an innermost position, that is, a rear position, possible in the obtuse angle so as to reduce a dimension of the internal combustion engine in a front-rear direction, the internal combustion engine is made compact as a whole without increasing the size thereof. [0013] According to the starter-motor arrangement structure of the internal combustion engine of claim 2, the\| oil pump is disposed at a place in the crankcase which is bn the rear side of the starter motor and near and substjantially under the crankshaft. Therefore, provision of the oil pump does not increase the size of the internal combu;tion engine, as well as an oil passage from the oil pujmp to the crankshaft can be made relatively short, thereby [enabling . smooth supply of a lubricating oil to the crankshaft. [0014] According to the starter-motor arrangement structure of the internal combustion engine of claim 3, the intermediate gear having the large-diameter gear ar\|.d the small-diameter gear integrally formed is interposed in meshing engagement between the starter drive gear disposed on the starter drive shaft protruding leftward from the motor main body of the starter motor disposed in tjie front portion of the crankcase and the starter driven gear rotatably journaled to the left shaft portion of the crankshaft. Thus, the starter motor is disposed oiji the right side with respect to a gear train in which the intermediate gear is interposed and which is dispoised on the left side. Hence, the front-rear dimension ofithe internal combustion engine as a whole including thje starter motor is made relatively small, thereby inhibiting the size of the internal combustion engine from increasing iand enabling to make the internal combustion engine cchmpact. [0015] According to the starter-motor arrangement structure of the internal combustion engine of claim 4, the:oil pump is disposed at a position to overlap with the starter driven gear in the side view on the right side of the vertical plane including the cylinder axis. The starter drive gear fitted on the left shaft portion of the crankshaft is located on the left iside of the vertical plane including the cylinder axis. Thus, by disposing the oil pump, which is located on the itight side thereof, at a position to overlap with the starter (iriven gear in the side view, the internal combustion engine can be made compact as a whole without increasing the front-rear dimension of the internal combustion engine. [0016] According to the starter-motor arrangement structure of the internal combustion engine of claim 5, the mount place supporting the internal combustion engine on the vehicle-body frame covers the starter motor disposed in the front portion of the crankcase from the front side, and the mount plate is such that a portion thereof corresponding to the power terminal protruding on the starter motor:expands. Thus, the mount plate covers the starter motor including the power terminal from the front side and can protect an entirety of the starter motor from impingement of foreign matter such as flying gravel. Therefore, it is possible to dispose the starter motor on the front lower side of the internal combustion engine, thereby enabling to maske the internal combustion engine compact as well as lower the center of gravity of the vehicle. [Brief Description of Drawings] [0017] [Fig. 1] Fig. 1 is a side view of a motorcycle Installed with an internal combustion engine according to one embodiment of the invention. [Fig. 2] Fig. 2 is a front view of a relevant portion of the internal combustion engine installed on a vehicle body. [Fig. 3] Fig. 3 is a left side view of the internal combustion engine in a state where a left case covei: is removed. I [Fig. 4] Fig. 4 is a right side view of the interinal combustion engine in a state where a right case covier is removed. [Fig. 5] Fig. 5 is a cross-sectional view of the internal combustion engine. [Fig. 6] Fig. 6 is a cross-sectional view taken atloriST line VI-VI in Fig. 5. [Fig. 7] Pig. 7 is a cross-sectional view taken along line VII-VII in Fig. 5. [Description of Embodiments] [0018] Hereinafter, there will be described one embodiment of the invention, referring to Figs. 1-7. Fig. 1 is an overall side view of a motorcycle 1 according to the embodiment. [0 019] A vehicle-body frame of the motorcycle 1 is Such that a pair of main frames 3, 3 on the right and left aides, respectively, extend rearward from a head tube 2 slightly downward, and then bend further downward to form Steeply inclined portions 3a, 3a, whose lower portions are bent frontward in an L-like shape to extend to a lower end. A pair of down frames 4, 4, on the right and left sides, respectively, extend from the head tube 2 Obliquely downward in an acute angle and parallel to the steeply inclined portions 3a of the main frames 3 in sidej view. [0020] From upper portions of the steeply inclined portions 3a, 3a of the main frames 3, 3, seat rails 5, 5 extlend rearward, and backstays 6, 6 connecting central portions of the seat rails 5, 5 and lower portions of the steeply inclined portions 3a, 3a support the seat rails 5, 5. [0021] In the vehicle-body frame, a front fork 7 is : pivotally supported on the head tube 2, a front whel 8 is rotatably journaled to a lower end of the front fotk 7, a rear fork 10 that is journaled at its front end tola pivot plate 9 disposed at the lower portions of the main frames 3, 3 where the main frames 3, 3 are bent in the L-likfe shape, a rear wheel 11 is rotatably journaled to a rear end of the rear fork 10, and a rear cushion 12 is interposed between a rear portion of the rear fork 10 and the central pprtions of the seat rails 5, 5. A fuel tank 13 is installed on a front portion of the main frames 3, 3, and a seat 14 is disposed on the rear side of the fuel tank 13 such that the seat 14 is isupported by the seat rails 5. [0022] An internal combustion engine 20 installed on the vehicle-body frame is a single-cylinder four-strojce internal combustion engine of SOHC type, and mounted in a position relative to a vehicle body such that a crankshaft 21 is oriented in a lateral direction of the vehicle body and a cylinder stands leaning slightly frontward.! A rear portion of a crankcase 22, to which th crankshaft 21 of the internal combustion engine 2 0 is rotatably journaled, also serves as a transmission case in which a transmission chamber is formed, and the internal combustion engine 20 constitutes a power unit. [0023] Over the crankcase 22 are superposed in order and integrally fastened a cylinder block 23 and a cylinder head 24, a cylinder head cover 25 covers the upper side of the cylinder head 24, and the cylinder block 23, the cylinder head 24, and the cylinder head cover 25 protrude from the crankcase 22 in a slightly frontward leaning position. [0024] The crankcase 22 is such that mount brackets :22fu, 22fl are formed to protrude frontward from upper left and right portions and lower left and right portions i\|i a front surface, and mount brackets 22ru, 22rl are formed to protrude rearward from upper left and right portions and lower left and right portions in a rear surface (dee Fig. 5) . [0025] The pair of down frames 4, 4 of the vehicle-body frame on the left and right sides extend downwardiparallel to each other, and an upper portion of a mount plate 15 is fixed with bolts 16 to attaching boss members 4b, 4b disposed in vertical relation to each other in a lower portion of each of the down frames 4, 4 (see Fig. 2). [0026] Referring to Figs. 2-4, the mount plate 15 ha$ a channel-like shape, having a front wall 15f that is curved upward at its lower portion and bent rearward at its left and right end portions to form left and right side walls 151, 15r whose upper portions extend and narrow rearward to form upper attaching portions 15fu, and curved lower end portions of the left and right side walls 151, 15riextend obliquely upward to form lower attaching portions iSfl. [0027] The internal combustion engine 2 0 is such that a front end portion of the crankcase 22 (where a stafter motor 70 is attached, as described later) is inserted from the rear side between the left and right side walls 151, 15r of the mount plate 15 that are fixed to both Ipwer end portions of the down frames 4, 4, and the mount brackets 22fu, 22fl at the front upper and lower sides of t\|he crankcase 22 are attached with support bolts 17, 17 to the upper attaching portions 15fu and the lower attaching portions 15fl of the mount plate 15, respectively,: in order that a front portion of the crankcase 22 is supported by the down frames 4, 4 via the mount plate 15. [0028] On the other hand, a rear portion of the crajikcase 22 is supported by the main frames 3, 3 via upper and lower attaching members 18ru, IBrl, with the mount brackets 22ru, 22rl at the rear upper and lower sides attached with support bolts 19, 19 to the upper attaching members 18ru protruding frontward from relatively lower portioifas of the steeply inclined portions 3a, 3a of the main framesis, 3 I and the lower attaching members 18rl protruding frontward from a cross member 3c connecting lower end portions of the main frames 3, 3 with each other. [0029] Thus, the internal combustion engine 20 is mounted on the vehicle-body frame such that two front-side places at upper and lower positions and two rear-side places :at upper and lower positions of the crankcase 22 are attached to the down frames 4, 4 and the main frames 3, 3 of the vehicle-body frame. [0030] From the cylinder head 24 of the internal cottlbustion engine 20 installed on the vehicle-body frame in this way, which leans slightly frontward, an intake pipe 2 6 lextends rearward. The intake pipe 26 is connected, via a throttle body 27, with an air cleaner 28 disposed in a space surrounded by the main frames 3, the seat rails 5, and the backstays 6 in side view (see Fig. 1). [0031] An exhaust pipe 29 extends frontward from thie cylinder head 24 and is bent downward and then bent rearward to extend rearward and right ward along an under surface of the crankcase 22 to be connected to a litiuffler 29M disposed on the right side of the rear wheel HI. [0032] '. Referring to Fig. 6, the crankcase 22 is sectioned in a left-right direction into a left crankcase 22L land a right crankcase 22R. The crankshaft 21 is rotatably journaled to a bearing wall 22Lw of the left crankcase 22L and a bearing wall 22Rw of the right crankcase 22R, via main bearings 31, 31. The crankshaft 21 is such that crank webs 21w, 21w are located in a crank chamber 22S between the bearing walls 22Lw, 22Rw, a left crankshaft portion 211 and; a right crankshaft portion 21r protrude leftward and rightWard out of the bearing walls 22Lw, 22Rw, and out sides thereof are covered by a left case cover 3 0L and a right case Cover 3OR, respectively. [0033] On the left crankshaft portion 211, a drive aiprocket 32 of a valve drive system is fitted in the vicinity of the main bearing 31. To the immediately left of the dtive sprocket 32, a starter driven gear 33 of a starting mechanism that has a large diameter is rotatably journaled. On the left side of the starter driven gear 33 is a one-way clutch 34, on the left side of which an outer rotor 35r of an AC generator 35 is fitted on a left end portioil of the left crankshaft portion 211. An inner stator 35s of the AC generator 35 that is disposed inside the outer rotor 35r is fixed on the left case cover 30L. [0034] On the other hand, a pump drive gear 36 of an oil pump 80 is fitted on the right crankshaft portion 21r. An inner case 37a of a centrifugal oil strainer 37 is spline- fitted and fixed with a nut 38 in a manner to clamp: the pump drive gear 36 from the right side. The inner case 3 7a having a cylindrical shape ; radially expands at its right end portion so as to iform a cup-shaped portion 37aa, and a right-side opening of the cup-shaped portion 37aa is covered by a platelike cover member 37b to form a strainer chamber 37s inside. [0035] The right crankshaft portion 21r protrudes rightward through the cover member 3 7b. A protruding end portion thereof is fitted in a cylindrical boss portion 30tb protruding from an inner side of the right case cover 3OR. In the right crankshaft portion 21r and the right crank web 21w, an oil passage 21ra is formed. The oil passage 21ra is in communication with the strainer; chamber 37s through a communication hole formed radially through a right end of the oil passage 21ra. At a right end of the right crankshaft portidn 21r is formed a right-end oil passage 21rb coaxially with the oil passage 21ra such that the right-end oil passage 21rb is communicated with an inside of the cylindrical boss portion 3Orb, and a communication hole formed radially through a left end of the right-end oil passage 21rb opens into the strainer chamber 37s. [0036] The right case cover 30R covering the centrifugal oil strainer 3 7 from the right side has an oil passage 30ra in its wall (see Fig. 7), and the oil passage 30ra communicates with the cylindrical boss portion 3Orb that is formed at a portion of the right case cover 3OR opposed to the crankshaft 21 so as to protrude inward. Thus, an oil flowing from the oil passage 30ra in the wall of the right case cover 30R to the cylindrical boss portion 30rb is introduced into the strainer chamber 37s of the centrifugal oil strainer 37 via the right-end oil passage 21rb and foreign matter is separated and removed from the oil by a centrifugal force, and then the oil is introduced into the oil passage 21ra of the crankshaft 21 to be supplied to a connecting portion between a crank pin 21p and a connecting rod 21c. [0037] As shown in Fig. 4, the oil pump 80 is disposed on the bearing wall 22Rw of the right crankcase 22R at a position substantially under the crankshaft 21. With respect to a vertical plane including a cylinder axis Lc (a vertical plane including a central axis: of the connecting rod 21c in Fig. 7), the oil pump 80 is located on the right side that is opposite to the starter driven gear 33 located on the left side, and the oil pump 80 is disposed at a position to overlap with the starter driven gear 33 in side view, as shown in Fig. 4. [0038] By the arrangement where the oil pump 8 0 located on the right side of the vertical plane including the cylinder axis Lc overlaps in side view with the starter driven gear 33 located on the left side thereof, the internal: combustion engine 20 including the oil pump 80 is made compact as a whole, without increasing a dimension of the internal combustion engine 20 in a front-rear direction. [0039] The oil pump 80 is a trochoid pump, and referring to Fig. 7, a pump base plate 81 and a pump housing 82 are fixed to the bearing wall 22Rw from the right side, and an outer rotor 83 and an inner rotor 84 rotate in engagement with each other eccentrically in the pump housing 82. [0040] A pump drive shaft 85 passing through the pump base plate 81 and the pump housing 82 in the left-right direction and rotatably journaled is fitted in the inner rotor 84 in the pump housing 82, and a pump driven gear 86 is fitted on an end portion thereof protruding rightward out of the pump housing 82. The pump driven gear 86 is in engagement with the pump drive gear 36 fitted on the right crankshaft portion 21r of the crankshaft 21. [0041] Thus, rotation of the crankshaft 21 rotates the pump drive shaft 8 5 via the engagement between the pump drive gear 3 6 and the pump driven gear 8 6 to drive the Oil pump 80 . Since the oil pump 80 is disposed substantially under the crankshaft 21 in the vicinity of the crankshaft 21 with a spacing corresponding to meshing engagement between a pair of gears, i.e., the pump drive gear 36 and the pump driven gear 86, the centrifugal oil strainer 37 at the right end portion of the crankshaft 21 is at a position relatively near the oil pump 80. [0042] Thus, the oil passage from the oil pump 80 to;the oil passage 21ra of the crankshaft 21 is made relatively short, thereby enabling smooth supply of the oil to the connecting portion between the crank pin 21p and the connecting rod 21c. [0043] On the other hand, a valve system is formed in the cylinder head 24 such that a cam shaft 40 is rotatably journaled in an orientation parallel to the lateral direction of the vehicle body at an upper surface of the cylinder head 24 by being clamped by a camshaft holder 41. On a left end of the camshaft 40 is fitted a driven sprocket 42 having a diameter substantially twice that of the drive sprocket 32 of the valve drive system. [0044] A cam roller chain 43 which is an endless power transmission chain is wound between the driven sprocket 42 fitted on the camshaft 40 and the drive sprocket 32 fitted on the crankshaft 21, and rotation of the crankshaft 21 is transmitted to the camshaft 40 with a rotational; speed of the crankshaft 21 reduced to half. [0045] The cam roller chain 43 is not a silent chain but is a roller chain. The cam roller chain 43 is disposed in cam chin I chambers 22C, 23C and 24C of the crankcase 22, the (cylinder block 23, and the cylinder head 24. [0046] In the cam chain chamber 23C of the cylinder block 23, a guide roller 44 having a diameter between those of the drive sprocket 32 and the driven sprocket 42 is rotatably journaled, and guides rotation of the cam roller chain 43 at the front and rear sides. [0047] The cam chain chamber 22C of the left crankcase 22L forms a space in common with an ACG chamber where the AC generator 3 5 is covered by the left case cover SOL, and a space surrounded by a circumferential wall 22Ls extending at the left side of the crankcase 22 in the vicinity of the left-side bearing wall 22Lw corresponds to the cam chain chamber 22C. [0048] As shown in Fig. 5, in the cam chain chamber 22C, a guide roller 45 is rotatably journaled to the left-side bearing wall 22Lw at a position on the front side;of and obliquely above the drive sprocket 32 so as to guide rotation of the cam roller chain 32 on the front side. In the cam chain chamber 22C and on the rear side of the drive sprocket 32, a tensioner arm 51 of a cam-chain tensioning device 50 is swingably provided by being journaled at its center to a pivot bolt 52. At an upper, distal end of the tensioner arfn 51, a tensioner roller 53 is rotatably journaled. A loweir end of the arm constitutes a contact end 51e. [0049] Since a push rod 56 of a tensioner lifter 55 is in pressing contact with the contact end 51e of the tensioner arm 51 to bias the tensioner arm 51, the tensioner roller 53 at the upper, distal end of the arm pushes the rotating portion of the cam roller chain 43 on the rear side so as to place an appropriate tension on the cam roller dhain 43. [0050] A guide bore 57 is formed obliquely through am inclined portion of the circumferential wall 22Ls extending leftward from the left-side bearing wall 22Lw of the left crankcase 22L, which portion is below the drive sprocket 32, such that an upper portion of the guide bore 57 is:located inside the circumferential wall 22Ls, and a lower portion of the guide bore 57 is located outside the circumferential wall 22Ls and on the front side of the upper portion thereof, and thus the guide bore 57 communicates the cam chain chamber 22C with the outside thereof (see Fig. 5). [0051] A side wall plate 59 is attached at a left surface of the upper portion of the guide bore 57 above the circumferential wall 22Ls, so as to form an oil siimp 60. A lower half of the guide bore 57 is formed in a guide cylindrical portion 58 extending from the circumferential wall 22Ls obliquely downward. An open lower end Of the guide cylindrical portion 58 is closed by a tensioner bolt 63 . [0052] The push rod 56 inserted and fitted in the guide bore 57 is cylindrical, and has an open upper end, on which a head member 56h formed of rubber is fitted, and ari open lower end at which a control valve 61 is disposed ; (see Fig. 6) . The control valve 61 is constructed such that a valve seat 61s, which has a bottomed cylindrical shape such that a circular hole is formed through a bottom wall, is fitted in the push rod 56 on the slightly inner side of the lower open end of the push rod 56, a ball 61b is loosely fitted in the cylinder of the valve seat 61s, and a cylindrical bottomed valve cap 61c is disposed at the opening iof the valve seat 61s in order that the circular hole of jthe valve seat 61s is openable and closable by the ball 61b with the ball 61b prevented from dropping out. [0053] When a compression spring 62 is inserted into the guide bore 57 from the lower open end of the guid cylindrical portion 5 8 and the lower open end is cplosed by the tensioner bolt 63, the push rod 56 is biased by the compression spring 62 obliquely upward. [0054] The head member 5 6h at the upper end of the push rod 56 thus biased obliquely upward by the compression spring 62 is in contact with the contact end 51e of the pensioner arm 51 to swingably bias the tensioner arm 51 in counterclockwise direction as seen in a side view jof Fig. 5, whereby the tensioner roller 53 at the other end ojf the tensioner arm 51 pushes the rotating portion of the cam roller chain 43 on the rear side so as to place a constant tension on the cam roller chain 43. [0055] The oil accumulated in the oil sump 60 fills a circular hole formed in a cylindrical wall of the jpush rod 56, an inside of the push rod 56, and also a portion of the guide bore 57 of the guide cylindrical portion 58 at the control valve 61 and below the control valve 61 where the compression spring 62 is disposed. By an operatioti of the control valve 61 to control flow of the oil, the piush rod 56 is prevented from retracting but is allowed only to advance, whereby the tensioner lifter 55 prevents islack of the roller chain 43 and can maintain an appropriate tension on the cam roller chain 43. [0056] In the internal combustion engine 20, a starter motor 70 is disposed on the front side of the crankcase 22. Referring to Fig. 5, the starter motor 70 is disposed within an obtuse angle, as seen in the side view of Fig. 5, formed on the front side between the cylinder axis Lc, which is the central axis of a cylinder bore of the cylinder block 23 of the internal combustion engihe 20 that stands upright with a slight frontward leaning, and a rod axis Lr (a central axis of the guide bore 57 into,which the push rod 56 is slidably inserted) of the push rodj 56 of the tensioner lifter 55. [0057] The cam roller chain 43 transmitting power toj the valve system is small in friction as compared to a silent chain, but instead requires the tensioner arm 51 and the push rod 56, necessitating disposing the starter motor 70 at a position other than where the cam roller chain 43, the push rod 56, and others are disposed. [0058] Where the starter motor 70 is disposed in a apace of the obtuse angle formed between the cylinder axis tc and the rod axis Lr, the starter motor 70 can be disponed an innermost position in the obtuse angle or as nearest as possible an intersection between the cylinder and rod axes Lc, Lr, in the side view, without interfering with the cylinder block 23 and the tensioner lifter 55. Hence, the dimension of the internal combustion engine 2 0 in the front-rear direction is made small, which prevents increase in the size of the internal combustion engine 20 and enables to make compact as a whole the internal combustion engine 20 including the starter motor 70. [0059] In a front wall of the left crankcase 22L within the space of the obtuse angle, a portion between the mount brackets 22fu, 22fl protruding frontward from uppr and lower portions extends frontward to form a motor attaching wall 22M for the starter motor 70 (see Fig. 5), and the circumferential wall 22Ls is formed at an end of the frontward extending motor attaching wall 22M. A starter drive shaft 73 of the starter motor 70 is inserted in a circular hole 22mh formed on the inner side of the circumferential wall 22Ls of the motor attaching wall 22M (see Fig. 7). [0060] Referring to Fig. 7, the starter motor 70 is such that an open end portion of a main body casing 71 having a bottomed cylindrical shape is covered by a bearing lid member 72, and the starter drive shaft 73 passes through and protrudes from a bearing boss portion 72b protruding on the bearing lid member 72. On the bearing lid member 72, a power terminal 74 for electrical power supply protrudes radially. The starter motor 70 is disposed on the motor attaching wall 22M from the right side, and the bearing boss portion 72b is fitted in the circular hole 22mh and the bearing lid member 72 is fixed to the motor attaching wall 22M with a bolt 75. [0061] The starter drive shaft 73, which protrudes leftward from the bearing boss portion 72b of the starter motor 70 fixed on the motor attaching wall 22M, protrudes inside the circumferential wall 22Ls of the left crankcase 22L and along a frontmost protruding portion of the circular wall 22Ls, and a starter drive gear 73g is formed at an end portion of the starter drive shaft 73. [0062] Obliquely above and on the rear side of the tarter drive gear 73g, an intermediate gear 77 is rotatably journaled to an intermediate gear shaft 76 disposed between the motor attaching wall 22M of the left crankcase 22L and the left case cover 30L (see Fig. 7). [0063] The intermediate gear 77 is such that a larg-diameter gear 77b and a small-diameter gear 77s are integrally formed side by side. The large-diameter gear 77b is in engagement with the starter drive gear 73g formed on the starter drive shaft 73 of the starter motor 70, and the small-diameter gear 77s is engagement with the starter driven gear 3 3 rotatably journaled to the crankshaft 21 that is further obliquely above and on the rear side (see Figs. 3 and 7). [0064] In this way, the starting mechanism is disposed on the front side of the starter driven gear 3 3 rotatably journaled to on the crankshaft 21. When the starter motor 70 is driven, rotation of the starter drive shaft 73 is transmitted to the starter driven gear 3 3 via the intermediate gear 77 with the speed reduced, and the rotation is transmitted from the starter driven gear 33 to the crankshaft 21 via the one-way clutch 34, thereby starting the internal combustion engine 20. [0065] The intermediate gear 77 in which the large-diameter gear 77b and the small-diameter gear 77s are integrally formed is interposed between the starter drive geaif 73g formed on the starter drive shaft 73 leftward protifuding from the motor main body 71 of the starter motor 70 and the starter driven gear 33 rotatably journaled to the left crankshaft portion 211 of the crankshaft 21. According to this arrangement, as shown in Fig. 7, with respectito the center of the crankshaft 21, a gear train are arranged via the intermediate gear 77 on the left side and the $tarter motor is disposed on the right side. Hence, the dimension of the internal combustion engine 2 0 in the front-rear direction is made small, which prevents increase in the size of the internal combustion engine 20 and enables to make compact as a whole the internal combustion engine 2 0 including the starter motor 70. [0066] The mount plate 15 covering the starter motor 70 attached along the outer wall surface of the front wall of the crankcase 22 has a channel-like shape having the front wall 15f and left and right side walls 151, 15r that are rearward curved at their lower portions along the main body casing 71 of the starter motor 70. At a left side: of the front wall 15f is formed a front-wall expanding portion 15fb expanding frontward so as to cover the bearirtg lid member 72 radially larger than the main body casihg 71 and the power terminal 74 protruding from the bearing lid member 72. [0067] On the right side wall 15r is formed a right-wall expanding portion 15rb expanding rightward so as tio cover a right end portion of the main body casing 71 of thje starter motor 7 0 from the front side. A lower end of the front wall 15f of the mount plate 15 is located below the internal combustion enginej 20. [0068] As described above, since the mount plate 15; supporting the internal combustion engine 2 0 on the vehicle-body frame covers the front and lower sidds of the starter motor 70 disposed at the front wall of the crankcase 22, an entirety of the starter motor 70 can be protected from impingement of foreign matter such as flying gravel. Thus, it is enabled to dispose the starter motor 70 on the front lower side of the internal combustion engine 20, thereby enabling to make the internal combustion engine 2 0 compact as well as lower the center of gravity of the vehicle. [0069] The mount plate 15 is disposed with a lower pnd of its front wall 15f located below the internal combustion engine 2 0 to protect a lower portion of the internal combustion engine 20 also from flying gravel and others. [0070] Since the oil pump 80 is disposed in the crankcase 22 at a place near and substantially under the crankshaft 21 and on the rear side of the starter motor 70, provision of the oil pump 80 does not increase the size of the internal combustion engine. [Reference Signs List] [0071] 1... Motorcycle, 2... Head tube, 3... Main frame, 4... Down frame, 5... Seat rail, 6... Backstay, 7... Front fork, 8... Front wheel, 9... Pivot plate, 10... Rear fork, 11... Rear wheel, 12... Rear cushion, 13... Fuel tank, 14... Seat, 15... Mount plate, 16... Bolt, 17... Support bolt, 18ru... Upper attaching member, ISrl... Lower attaching member, 19... Support bolt, 20... Internal combustion engine, 21... Crankshaft, 211... Left crankshaft portion, 21r... Right crankshaft portion, 21w... Crank web, 22... Crankcase, 23... Cylinder block, 24... Cylinder head, 25... Cylinder head cover, 26,.. Intake pipe, 27... Throttle body, 28... Air cleaner, 2 9... Exhaust pipe, SOL... Left case cover, 3OR... Right case cover, 31... Main bearing, 32... Drive sprocket, 33... Starter driven gear, 34... One-way clutch, 35... AC generator, 3 6... Pump drive gear, 37... Centrifugal oil strainer, 3 8... Nut, 40... Camshaft, 41... Camshaft holder, 42... Driven sprocket, 43... Cam roller chain, 44... Guide roller, 45... Guide roller, 50... Cam-chain tensioning device, 51... Tensioner arm, 52... Pivot bolt, 53... Tensioner roller, 55... Tensioner lifter. 56... Push rod, 57... Guide bore, 58... Guide cylindrical portion, 59... Side wall plate, 60... Oil sump, 61... Control valve, 62... Compression spring, 63... Tensioner bolt, 70... Starter motor, 71... Motor main body, 72... Bearing lid member, 73... Starter drive shaft, 74... Power terminal, 75... Bolt, 76... Intermediate gear shaft, 77... Intermediate gear, 8 0... Oil pump, 81... Pump base plate, 82... Pump housing, 83... Outer rotor, 84... Inner rotor 8 5... Pump drive shaft, 86... Pump driven gear [Document Name] Scope of Claims [Claim 1] A starter-motor arrangement structure of an internal combustion engine in which: a crankshaft is rotatably journaled to a crankcase of the internal combustion engine installed on a motorcycle such that the crankshaft is oriented in a left-right direction, an endless roller chain is wound between a diive sprocket fitted on the crankshaft and a driven sprocket fitted on a cam shaft of a valve system, the roller chain is pushed by a pressing member, and the pressing member is in pressing contact with a push rod inserted and slidably fitted in a guide bore formed in the crankcase, wherein the push rod is disposed such that a rod axis thereof forms an obtuse angle on a front side in a side view with a cylinder axis of a cylinder standing on the crankcase, and wherein the starter motor is disposed in a front portion of the crankcase within the obtuse angle formed between the cylinder axis and the rod axis. [Claim 2] The starter-motor arrangement structure of the internal combustion engine according to claim 1, wherein an oil pump is disposed at a place in the crankcase near and substantially under the crankshaft on a rear side of the starter motor. [Claim 3] The starter-motor arrangement structure of tlie internal combustion engine according to claim 1 or 2, wherein a starter drive gear is disposed on starter drive shaft protruding leftward from a motor main ibody of the starter motor, wherein a starter driven gear is rotatably journaled to a left shaft portion of the crankshaft, and wherein an intermediate gear having a large-ciameter gear and a small-diameter gear that are integrally formed is interposed between and in meshing engagement with the starter drive gear and the starter driven gear. [Claim 4] The starter-motor arrangement structure of the internal combustion engine according to claim 3, wherein the oil pump is disposed at a position to overlap with the starter driven gear in a side view on a right side of a vertical plane including the cylinder axis. [Claim 5] The starter-motor arrangement structure of the internal combustion engine according to any one of claims 1 through 4, wherein a mount plate supporting the internal combustion engine on a vehicle-body frame covers the starter motor that is disposed in a front portion of the crankcase from a front side, and wherein the mount plate expands at a portion which corresponds to a power terminal protruding on the starter motor.

Full Text

[Document Name] Specification
[Title of the Invention] STARTER-MOTOR ARRANGEMENT
STRUCTURE OF INTERNAL COMBUSTION ENGINE
[Technical Field]
[0001]
The present invention relates to a structure iof arranging a starter motor in an internal combustion engine having a cam-chain tensioning device consisting of | a pushing means pushing a roller chain transmitting power to a valve system and a push rod in pressing contact iwith the pushing means. [Background Art] [0002]
In a case where a roller chain is employed ais a cam chain, the friction becomes less than the case ofia silent chain. However, the former case requires equipments occupying a large space such as a pushing means and a push rod, making it difficult to dispose a starter motbr without increasing the size of an internal combustion engine.
An example of such an internal combustion engine employing the roller chain and having a cam-chaini tensioning device such as the pushing means and the push rod is disclosed in Patent Literature 1. [Citation List] [Patent Literature]
[0003] I
[Patent Literature 1] JP Patent No. 4035226 [0004]

The internal combustion engine disclosed in Plitent Literature 1 is such that a cylinder extends frontward from a crankcase substantially horizontally, and thus a iroller chain is disposed to extend frontward from a crankshaft.
A tensioner arm as a pushing means and a pushj rod of a cam-chain tensioning device are disposed to intetsect the roller chain extending horizontally in a front-rea|: direction, in side view. [Summary of Invention] [Technical Problem] [0005]
A starter motor disposed around a starter driven gear that has a large diameter and is fitted on the crankshaft is disposed at a position obliquely above and on tihe rear side of the crankshaft, which is other than wherejmembers including the roller chain extending frontward ofithe crankshaft (starter driven gear) and an oil colletiting chamber above the crankshaft.
Since the roller chain extends frontward ofithe
crankshaft and the starter motor protrudes obliquely above
and on the rear side of the crankshaft, the size of the
internal combustion engine including the starter (motor is
inevitably large. ]
[0006]
The present invention has been developed inj view of the foregoing, and an object thereof is to provide a starter-motor arrangement structure that preventi the size of an internal combustion engine having a rollerj-chain

tensioning device from becoming large, and can make:such an internal combustion engine compact as a whole. [Solution to Problem] [0007]
To attain the above object, an arrangement of the invention according to claim 1 provides a starter-motor arrangement structure of an internal combustion engjine in which: a crankshaft is rotatably journaled to a crnkcase of the internal combustion engine installed on a mdtorcycle such that the crankshaft is oriented in a left-right direction, an endless roller chain is wound betweeili a drive sprocket fitted on the crankshaft and a driven sprcket fitted on a cam shaft of a valve system, the roller chain is pushed by a pressing member; and the pressing member is in pressing contact with a push rod inserted and sjlidably fitted in a guide bore formed in the crankcase, wherein the push rod is disposed such that a rod axis thereof forms an obtuse angle on a front side in a side view with a cylinder axis of a cylinder standing on the crankGase, and wherein the starter motor is disposed in a front 5)ortion of the crankcase within the obtuse angle formed between the cylinder axis and the rod axis. [0008]
An arrangement of the invention according t
starter motor. [0009]
An arrangement of the invention according to claim 3 provides the starter-motor arrangement structure of, the internal combustion engine according to claim 1 or ;2, wherein a starter drive gear is disposed on a startjer drive shaft protruding leftward from a motor main body of the starter motor, wherein a starter driven gear is rotatably journaled to a left shaft portion of the crankshaft, and wherein an intermediate gear having a large-diameter gear and a small-diameter gear that are integrally formjed is interposed between and in meshing engagement with the starter drive gear and the starter driven gear. [0010]
An arrangement of the invention according td claim 4 provides the starter-motor arrangement structure of the internal combustion engine according to claim 3, yrherein the oil pump is disposed at a position to overlap with the starter driven gear in a side view on a right side of a vertical plane including the cylinder axis. [0011]
An arrangement of the invention according to claim 5 provides the starter-motor arrangement structure! of the internal combustion engine according to any one bf claims 1 through 4, wherein a mount plate supporting the internal combustion engine on a vehicle-body frame covers the starter motor that is disposed in a front portion of the crankcase from a front side, and wherein the moiint plate

expands at a portion which corresponds to a power terminal protruding on the starter motor.
[Advantageous Effect of Invention]
[0012]
According to the starter-motor arrangement structure of the internal combustion engine of claim 1, the jstarter motor is disposed within the obtuse angle facing frontward formed in the side view between the cylinder axis iof the cylinder standing from the crankcase (a central ajis of a cylinder bore) and the rod axis of the push rod (a central axis of a guide bore in which the push rod is insejrted and slidably fitted). Therefore, by locating the stajrter motor, which is disposed in the front portion of the craiikcase, at an innermost position, that is, a rear position, possible in the obtuse angle so as to reduce a dimension of the internal combustion engine in a front-rear direction, the internal combustion engine is made compact as a whole without increasing the size thereof.
[0013]
According to the starter-motor arrangement structure of the internal combustion engine of claim 2, the| oil pump is disposed at a place in the crankcase which is bn the rear side of the starter motor and near and substjantially under the crankshaft. Therefore, provision of the oil pump does not increase the size of the internal combu;tion engine, as well as an oil passage from the oil pujmp to the crankshaft can be made relatively short, thereby [enabling . smooth supply of a lubricating oil to the crankshaft.

[0014]
According to the starter-motor arrangement structure of the internal combustion engine of claim 3, the intermediate gear having the large-diameter gear ar|.d the small-diameter gear integrally formed is interposed in meshing engagement between the starter drive gear disposed on the starter drive shaft protruding leftward from the motor main body of the starter motor disposed in tjie front portion of the crankcase and the starter driven gear rotatably journaled to the left shaft portion of the crankshaft. Thus, the starter motor is disposed oiji the right side with respect to a gear train in which the intermediate gear is interposed and which is dispoised on the left side. Hence, the front-rear dimension ofithe internal combustion engine as a whole including thje starter motor is made relatively small, thereby inhibiting the size of the internal combustion engine from increasing iand enabling to make the internal combustion engine cchmpact.
[0015]
According to the starter-motor arrangement structure of the internal combustion engine of claim 4, the:oil pump is disposed at a position to overlap with the starter driven gear in the side view on the right side of the vertical plane including the cylinder axis.
The starter drive gear fitted on the left shaft portion of the crankshaft is located on the left iside of the vertical plane including the cylinder axis. Thus, by disposing the oil pump, which is located on the itight side

thereof, at a position to overlap with the starter (iriven gear in the side view, the internal combustion engine can be made compact as a whole without increasing the front-rear dimension of the internal combustion engine. [0016]
According to the starter-motor arrangement structure of the internal combustion engine of claim 5, the mount place supporting the internal combustion engine on the vehicle-body frame covers the starter motor disposed in the front portion of the crankcase from the front side, and the mount plate is such that a portion thereof corresponding to the power terminal protruding on the starter motor:expands. Thus, the mount plate covers the starter motor including the power terminal from the front side and can protect an entirety of the starter motor from impingement of foreign matter such as flying gravel. Therefore, it is possible to dispose the starter motor on the front lower side of the internal combustion engine, thereby enabling to maske the internal combustion engine compact as well as lower the center of gravity of the vehicle. [Brief Description of Drawings] [0017]
[Fig. 1] Fig. 1 is a side view of a motorcycle Installed with an internal combustion engine according to one embodiment of the invention.
[Fig. 2] Fig. 2 is a front view of a relevant portion of the internal combustion engine installed on a vehicle body. [Fig. 3] Fig. 3 is a left side view of the internal

combustion engine in a state where a left case covei: is
removed. I
[Fig. 4] Fig. 4 is a right side view of the interinal
combustion engine in a state where a right case covier is
removed.
[Fig. 5] Fig. 5 is a cross-sectional view of the internal
combustion engine.
[Fig. 6] Fig. 6 is a cross-sectional view taken atloriST
line VI-VI in Fig. 5.
[Fig. 7] Pig. 7 is a cross-sectional view taken along
line VII-VII in Fig. 5.
[Description of Embodiments]
[0018]
Hereinafter, there will be described one embodiment of the invention, referring to Figs. 1-7.
Fig. 1 is an overall side view of a motorcycle 1 according to the embodiment. [0 019]
A vehicle-body frame of the motorcycle 1 is Such that a pair of main frames 3, 3 on the right and left aides, respectively, extend rearward from a head tube 2 slightly downward, and then bend further downward to form Steeply inclined portions 3a, 3a, whose lower portions are bent frontward in an L-like shape to extend to a lower end.
A pair of down frames 4, 4, on the right and left sides, respectively, extend from the head tube 2 Obliquely downward in an acute angle and parallel to the steeply inclined portions 3a of the main frames 3 in sidej view.

[0020]
From upper portions of the steeply inclined portions 3a, 3a of the main frames 3, 3, seat rails 5, 5 extlend rearward, and backstays 6, 6 connecting central portions of the seat rails 5, 5 and lower portions of the steeply inclined portions 3a, 3a support the seat rails 5, 5.
[0021]
In the vehicle-body frame, a front fork 7 is : pivotally supported on the head tube 2, a front whel 8 is rotatably journaled to a lower end of the front fotk 7, a rear fork 10 that is journaled at its front end tola pivot plate 9 disposed at the lower portions of the main frames 3, 3 where the main frames 3, 3 are bent in the L-likfe shape, a rear wheel 11 is rotatably journaled to a rear end of the rear fork 10, and a rear cushion 12 is interposed between a rear portion of the rear fork 10 and the central pprtions of the seat rails 5, 5.
A fuel tank 13 is installed on a front portion of the main frames 3, 3, and a seat 14 is disposed on the rear side of the fuel tank 13 such that the seat 14 is isupported by the seat rails 5.
[0022]
An internal combustion engine 20 installed on the vehicle-body frame is a single-cylinder four-strojce internal combustion engine of SOHC type, and mounted in a position relative to a vehicle body such that a crankshaft 21 is oriented in a lateral direction of the vehicle body and a cylinder stands leaning slightly frontward.!

A rear portion of a crankcase 22, to which th crankshaft 21 of the internal combustion engine 2 0 is rotatably journaled, also serves as a transmission case in which a transmission chamber is formed, and the internal combustion engine 20 constitutes a power unit. [0023]
Over the crankcase 22 are superposed in order and integrally fastened a cylinder block 23 and a cylinder head 24, a cylinder head cover 25 covers the upper side of the cylinder head 24, and the cylinder block 23, the cylinder head 24, and the cylinder head cover 25 protrude from the crankcase 22 in a slightly frontward leaning position. [0024]
The crankcase 22 is such that mount brackets :22fu, 22fl are formed to protrude frontward from upper left and right portions and lower left and right portions i|i a front surface, and mount brackets 22ru, 22rl are formed to protrude rearward from upper left and right portions and lower left and right portions in a rear surface (dee Fig. 5) . [0025]
The pair of down frames 4, 4 of the vehicle-body frame on the left and right sides extend downwardiparallel to each other, and an upper portion of a mount plate 15 is fixed with bolts 16 to attaching boss members 4b, 4b disposed in vertical relation to each other in a lower portion of each of the down frames 4, 4 (see Fig. 2). [0026]

Referring to Figs. 2-4, the mount plate 15 ha$ a channel-like shape, having a front wall 15f that is curved upward at its lower portion and bent rearward at its left and right end portions to form left and right side walls 151, 15r whose upper portions extend and narrow rearward to form upper attaching portions 15fu, and curved lower end portions of the left and right side walls 151, 15riextend obliquely upward to form lower attaching portions iSfl. [0027]
The internal combustion engine 2 0 is such that a front end portion of the crankcase 22 (where a stafter motor 70 is attached, as described later) is inserted from the rear side between the left and right side walls 151, 15r of the mount plate 15 that are fixed to both Ipwer end portions of the down frames 4, 4, and the mount brackets 22fu, 22fl at the front upper and lower sides of t|he crankcase 22 are attached with support bolts 17, 17 to the upper attaching portions 15fu and the lower attaching portions 15fl of the mount plate 15, respectively,: in order that a front portion of the crankcase 22 is supported by the down frames 4, 4 via the mount plate 15. [0028]
On the other hand, a rear portion of the crajikcase 22 is supported by the main frames 3, 3 via upper and lower attaching members 18ru, IBrl, with the mount brackets 22ru, 22rl at the rear upper and lower sides attached with support bolts 19, 19 to the upper attaching members 18ru protruding frontward from relatively lower portioifas of the

steeply inclined portions 3a, 3a of the main framesis, 3
I
and the lower attaching members 18rl protruding frontward from a cross member 3c connecting lower end portions of the main frames 3, 3 with each other. [0029]
Thus, the internal combustion engine 20 is mounted on the vehicle-body frame such that two front-side places at upper and lower positions and two rear-side places :at upper and lower positions of the crankcase 22 are attached to the down frames 4, 4 and the main frames 3, 3 of the vehicle-body frame. [0030]
From the cylinder head 24 of the internal cottlbustion engine 20 installed on the vehicle-body frame in this way, which leans slightly frontward, an intake pipe 2 6 lextends rearward. The intake pipe 26 is connected, via a throttle body 27, with an air cleaner 28 disposed in a space surrounded by the main frames 3, the seat rails 5, and the backstays 6 in side view (see Fig. 1). [0031]
An exhaust pipe 29 extends frontward from thie
cylinder head 24 and is bent downward and then bent
rearward to extend rearward and right ward along an under
surface of the crankcase 22 to be connected to a litiuffler
29M disposed on the right side of the rear wheel HI.
[0032] '.
Referring to Fig. 6, the crankcase 22 is sectioned in a left-right direction into a left crankcase 22L land a

right crankcase 22R. The crankshaft 21 is rotatably journaled to a bearing wall 22Lw of the left crankcase 22L and a bearing wall 22Rw of the right crankcase 22R, via main bearings 31, 31.
The crankshaft 21 is such that crank webs 21w, 21w are located in a crank chamber 22S between the bearing walls 22Lw, 22Rw, a left crankshaft portion 211 and; a right crankshaft portion 21r protrude leftward and rightWard out of the bearing walls 22Lw, 22Rw, and out sides thereof are covered by a left case cover 3 0L and a right case Cover 3OR, respectively. [0033]
On the left crankshaft portion 211, a drive aiprocket 32 of a valve drive system is fitted in the vicinity of the main bearing 31. To the immediately left of the dtive sprocket 32, a starter driven gear 33 of a starting mechanism that has a large diameter is rotatably journaled. On the left side of the starter driven gear 33 is a one-way clutch 34, on the left side of which an outer rotor 35r of an AC generator 35 is fitted on a left end portioil of the left crankshaft portion 211.
An inner stator 35s of the AC generator 35 that is disposed inside the outer rotor 35r is fixed on the left case cover 30L. [0034]
On the other hand, a pump drive gear 36 of an oil pump 80 is fitted on the right crankshaft portion 21r. An inner case 37a of a centrifugal oil strainer 37 is spline-

fitted and fixed with a nut 38 in a manner to clamp: the pump drive gear 36 from the right side.
The inner case 3 7a having a cylindrical shape ; radially expands at its right end portion so as to iform a cup-shaped portion 37aa, and a right-side opening of the cup-shaped portion 37aa is covered by a platelike cover member 37b to form a strainer chamber 37s inside. [0035]
The right crankshaft portion 21r protrudes rightward through the cover member 3 7b. A protruding end portion thereof is fitted in a cylindrical boss portion 30tb protruding from an inner side of the right case cover 3OR.
In the right crankshaft portion 21r and the right crank web 21w, an oil passage 21ra is formed. The oil passage 21ra is in communication with the strainer; chamber 37s through a communication hole formed radially through a right end of the oil passage 21ra.
At a right end of the right crankshaft portidn 21r is formed a right-end oil passage 21rb coaxially with the oil passage 21ra such that the right-end oil passage 21rb is communicated with an inside of the cylindrical boss portion 3Orb, and a communication hole formed radially through a left end of the right-end oil passage 21rb opens into the strainer chamber 37s. [0036]
The right case cover 30R covering the centrifugal oil strainer 3 7 from the right side has an oil passage 30ra in its wall (see Fig. 7), and the oil passage 30ra

communicates with the cylindrical boss portion 3Orb that is formed at a portion of the right case cover 3OR opposed to the crankshaft 21 so as to protrude inward. Thus, an oil flowing from the oil passage 30ra in the wall of the right case cover 30R to the cylindrical boss portion 30rb is introduced into the strainer chamber 37s of the centrifugal oil strainer 37 via the right-end oil passage 21rb and foreign matter is separated and removed from the oil by a centrifugal force, and then the oil is introduced into the oil passage 21ra of the crankshaft 21 to be supplied to a connecting portion between a crank pin 21p and a connecting rod 21c. [0037]
As shown in Fig. 4, the oil pump 80 is disposed on the bearing wall 22Rw of the right crankcase 22R at a position substantially under the crankshaft 21.
With respect to a vertical plane including a cylinder axis Lc (a vertical plane including a central axis: of the connecting rod 21c in Fig. 7), the oil pump 80 is located on the right side that is opposite to the starter driven gear 33 located on the left side, and the oil pump 80 is disposed at a position to overlap with the starter driven gear 33 in side view, as shown in Fig. 4. [0038]
By the arrangement where the oil pump 8 0 located on the right side of the vertical plane including the cylinder axis Lc overlaps in side view with the starter driven gear 33 located on the left side thereof, the internal:

combustion engine 20 including the oil pump 80 is made compact as a whole, without increasing a dimension of the internal combustion engine 20 in a front-rear direction. [0039]
The oil pump 80 is a trochoid pump, and referring to Fig. 7, a pump base plate 81 and a pump housing 82 are fixed to the bearing wall 22Rw from the right side, and an outer rotor 83 and an inner rotor 84 rotate in engagement with each other eccentrically in the pump housing 82. [0040]
A pump drive shaft 85 passing through the pump base plate 81 and the pump housing 82 in the left-right direction and rotatably journaled is fitted in the inner rotor 84 in the pump housing 82, and a pump driven gear 86 is fitted on an end portion thereof protruding rightward out of the pump housing 82.
The pump driven gear 86 is in engagement with the pump drive gear 36 fitted on the right crankshaft portion 21r of the crankshaft 21. [0041]
Thus, rotation of the crankshaft 21 rotates the pump drive shaft 8 5 via the engagement between the pump drive gear 3 6 and the pump driven gear 8 6 to drive the Oil pump 80 .
Since the oil pump 80 is disposed substantially under the crankshaft 21 in the vicinity of the crankshaft 21 with a spacing corresponding to meshing engagement between a pair of gears, i.e., the pump drive gear 36 and the pump

driven gear 86, the centrifugal oil strainer 37 at the right end portion of the crankshaft 21 is at a position relatively near the oil pump 80. [0042]
Thus, the oil passage from the oil pump 80 to;the oil passage 21ra of the crankshaft 21 is made relatively short, thereby enabling smooth supply of the oil to the connecting portion between the crank pin 21p and the connecting rod 21c. [0043]
On the other hand, a valve system is formed in the cylinder head 24 such that a cam shaft 40 is rotatably journaled in an orientation parallel to the lateral direction of the vehicle body at an upper surface of the cylinder head 24 by being clamped by a camshaft holder 41. On a left end of the camshaft 40 is fitted a driven sprocket 42 having a diameter substantially twice that of the drive sprocket 32 of the valve drive system. [0044]
A cam roller chain 43 which is an endless power transmission chain is wound between the driven sprocket 42 fitted on the camshaft 40 and the drive sprocket 32 fitted on the crankshaft 21, and rotation of the crankshaft 21 is transmitted to the camshaft 40 with a rotational; speed of the crankshaft 21 reduced to half. [0045]
The cam roller chain 43 is not a silent chain but is a roller chain.

The cam roller chain 43 is disposed in cam chin
I chambers 22C, 23C and 24C of the crankcase 22, the (cylinder
block 23, and the cylinder head 24.
[0046]
In the cam chain chamber 23C of the cylinder block 23,
a guide roller 44 having a diameter between those of the
drive sprocket 32 and the driven sprocket 42 is rotatably
journaled, and guides rotation of the cam roller chain 43
at the front and rear sides.
[0047]
The cam chain chamber 22C of the left crankcase 22L forms a space in common with an ACG chamber where the AC generator 3 5 is covered by the left case cover SOL, and a space surrounded by a circumferential wall 22Ls extending at the left side of the crankcase 22 in the vicinity of the left-side bearing wall 22Lw corresponds to the cam chain chamber 22C. [0048]
As shown in Fig. 5, in the cam chain chamber 22C, a guide roller 45 is rotatably journaled to the left-side bearing wall 22Lw at a position on the front side;of and obliquely above the drive sprocket 32 so as to guide rotation of the cam roller chain 32 on the front side.
In the cam chain chamber 22C and on the rear side of the drive sprocket 32, a tensioner arm 51 of a cam-chain tensioning device 50 is swingably provided by being journaled at its center to a pivot bolt 52.
At an upper, distal end of the tensioner arfn 51, a

tensioner roller 53 is rotatably journaled. A loweir end of
the arm constitutes a contact end 51e.
[0049]
Since a push rod 56 of a tensioner lifter 55 is in pressing contact with the contact end 51e of the tensioner arm 51 to bias the tensioner arm 51, the tensioner roller 53 at the upper, distal end of the arm pushes the rotating portion of the cam roller chain 43 on the rear side so as to place an appropriate tension on the cam roller dhain 43. [0050]
A guide bore 57 is formed obliquely through am inclined portion of the circumferential wall 22Ls extending leftward from the left-side bearing wall 22Lw of the left crankcase 22L, which portion is below the drive sprocket 32, such that an upper portion of the guide bore 57 is:located inside the circumferential wall 22Ls, and a lower portion of the guide bore 57 is located outside the circumferential wall 22Ls and on the front side of the upper portion thereof, and thus the guide bore 57 communicates the cam chain chamber 22C with the outside thereof (see Fig. 5). [0051]
A side wall plate 59 is attached at a left surface of the upper portion of the guide bore 57 above the circumferential wall 22Ls, so as to form an oil siimp 60. A lower half of the guide bore 57 is formed in a guide cylindrical portion 58 extending from the circumferential wall 22Ls obliquely downward. An open lower end Of the guide cylindrical portion 58 is closed by a tensioner bolt

63 . [0052]
The push rod 56 inserted and fitted in the guide bore 57 is cylindrical, and has an open upper end, on which a head member 56h formed of rubber is fitted, and ari open lower end at which a control valve 61 is disposed ; (see Fig. 6) .
The control valve 61 is constructed such that a valve seat 61s, which has a bottomed cylindrical shape such that a circular hole is formed through a bottom wall, is fitted in the push rod 56 on the slightly inner side of the lower open end of the push rod 56, a ball 61b is loosely fitted in the cylinder of the valve seat 61s, and a cylindrical bottomed valve cap 61c is disposed at the opening iof the valve seat 61s in order that the circular hole of jthe valve seat 61s is openable and closable by the ball 61b with the ball 61b prevented from dropping out. [0053]
When a compression spring 62 is inserted into the guide bore 57 from the lower open end of the guid cylindrical portion 5 8 and the lower open end is cplosed by the tensioner bolt 63, the push rod 56 is biased by the compression spring 62 obliquely upward. [0054]
The head member 5 6h at the upper end of the push rod 56 thus biased obliquely upward by the compression spring 62 is in contact with the contact end 51e of the pensioner arm 51 to swingably bias the tensioner arm 51 in

counterclockwise direction as seen in a side view jof Fig. 5, whereby the tensioner roller 53 at the other end ojf the tensioner arm 51 pushes the rotating portion of the cam roller chain 43 on the rear side so as to place a constant tension on the cam roller chain 43. [0055]
The oil accumulated in the oil sump 60 fills a circular hole formed in a cylindrical wall of the jpush rod 56, an inside of the push rod 56, and also a portion of the guide bore 57 of the guide cylindrical portion 58 at the control valve 61 and below the control valve 61 where the compression spring 62 is disposed. By an operatioti of the control valve 61 to control flow of the oil, the piush rod 56 is prevented from retracting but is allowed only to advance, whereby the tensioner lifter 55 prevents islack of the roller chain 43 and can maintain an appropriate tension on the cam roller chain 43. [0056]
In the internal combustion engine 20, a starter motor 70 is disposed on the front side of the crankcase 22.
Referring to Fig. 5, the starter motor 70 is disposed within an obtuse angle, as seen in the side view of Fig. 5, formed on the front side between the cylinder axis Lc, which is the central axis of a cylinder bore of the cylinder block 23 of the internal combustion engihe 20 that stands upright with a slight frontward leaning, and a rod axis Lr (a central axis of the guide bore 57 into,which the push rod 56 is slidably inserted) of the push rodj 56 of the

tensioner lifter 55. [0057]
The cam roller chain 43 transmitting power toj the valve system is small in friction as compared to a silent chain, but instead requires the tensioner arm 51 and the push rod 56, necessitating disposing the starter motor 70 at a position other than where the cam roller chain 43, the push rod 56, and others are disposed. [0058]
Where the starter motor 70 is disposed in a apace of the obtuse angle formed between the cylinder axis tc and the rod axis Lr, the starter motor 70 can be disponed an innermost position in the obtuse angle or as nearest as possible an intersection between the cylinder and rod axes Lc, Lr, in the side view, without interfering with the cylinder block 23 and the tensioner lifter 55. Hence, the dimension of the internal combustion engine 2 0 in the front-rear direction is made small, which prevents increase in the size of the internal combustion engine 20 and enables to make compact as a whole the internal combustion engine 20 including the starter motor 70. [0059]
In a front wall of the left crankcase 22L within the space of the obtuse angle, a portion between the mount brackets 22fu, 22fl protruding frontward from uppr and lower portions extends frontward to form a motor attaching wall 22M for the starter motor 70 (see Fig. 5), and the circumferential wall 22Ls is formed at an end of the

frontward extending motor attaching wall 22M.
A starter drive shaft 73 of the starter motor 70 is inserted in a circular hole 22mh formed on the inner side of the circumferential wall 22Ls of the motor attaching wall 22M (see Fig. 7). [0060]
Referring to Fig. 7, the starter motor 70 is such that an open end portion of a main body casing 71 having a bottomed cylindrical shape is covered by a bearing lid member 72, and the starter drive shaft 73 passes through and protrudes from a bearing boss portion 72b protruding on the bearing lid member 72.
On the bearing lid member 72, a power terminal 74 for electrical power supply protrudes radially.
The starter motor 70 is disposed on the motor attaching wall 22M from the right side, and the bearing boss portion 72b is fitted in the circular hole 22mh and the bearing lid member 72 is fixed to the motor attaching wall 22M with a bolt 75. [0061]
The starter drive shaft 73, which protrudes leftward from the bearing boss portion 72b of the starter motor 70 fixed on the motor attaching wall 22M, protrudes inside the circumferential wall 22Ls of the left crankcase 22L and along a frontmost protruding portion of the circular wall 22Ls, and a starter drive gear 73g is formed at an end portion of the starter drive shaft 73. [0062]

Obliquely above and on the rear side of the tarter drive gear 73g, an intermediate gear 77 is rotatably journaled to an intermediate gear shaft 76 disposed between the motor attaching wall 22M of the left crankcase 22L and the left case cover 30L (see Fig. 7). [0063]
The intermediate gear 77 is such that a larg-diameter gear 77b and a small-diameter gear 77s are integrally formed side by side. The large-diameter gear 77b is in engagement with the starter drive gear 73g formed on the starter drive shaft 73 of the starter motor 70, and the small-diameter gear 77s is engagement with the starter driven gear 3 3 rotatably journaled to the crankshaft 21 that is further obliquely above and on the rear side (see Figs. 3 and 7). [0064]
In this way, the starting mechanism is disposed on the front side of the starter driven gear 3 3 rotatably journaled to on the crankshaft 21.
When the starter motor 70 is driven, rotation of the starter drive shaft 73 is transmitted to the starter driven gear 3 3 via the intermediate gear 77 with the speed reduced, and the rotation is transmitted from the starter driven gear 33 to the crankshaft 21 via the one-way clutch 34, thereby starting the internal combustion engine 20. [0065]
The intermediate gear 77 in which the large-diameter gear 77b and the small-diameter gear 77s are integrally

formed is interposed between the starter drive geaif 73g formed on the starter drive shaft 73 leftward protifuding from the motor main body 71 of the starter motor 70 and the starter driven gear 33 rotatably journaled to the left crankshaft portion 211 of the crankshaft 21. According to this arrangement, as shown in Fig. 7, with respectito the center of the crankshaft 21, a gear train are arranged via the intermediate gear 77 on the left side and the $tarter motor is disposed on the right side. Hence, the dimension of the internal combustion engine 2 0 in the front-rear direction is made small, which prevents increase in the size of the internal combustion engine 20 and enables to make compact as a whole the internal combustion engine 2 0 including the starter motor 70. [0066]
The mount plate 15 covering the starter motor 70 attached along the outer wall surface of the front wall of the crankcase 22 has a channel-like shape having the front wall 15f and left and right side walls 151, 15r that are rearward curved at their lower portions along the main body casing 71 of the starter motor 70. At a left side: of the front wall 15f is formed a front-wall expanding portion 15fb expanding frontward so as to cover the bearirtg lid member 72 radially larger than the main body casihg 71 and the power terminal 74 protruding from the bearing lid member 72. [0067]
On the right side wall 15r is formed a right-wall

expanding portion 15rb expanding rightward so as tio cover a right end portion of the main body casing 71 of thje starter motor 7 0 from the front side.
A lower end of the front wall 15f of the mount plate 15 is located below the internal combustion enginej 20. [0068]
As described above, since the mount plate 15; supporting the internal combustion engine 2 0 on the vehicle-body frame covers the front and lower sidds of the starter motor 70 disposed at the front wall of the crankcase 22, an entirety of the starter motor 70 can be protected from impingement of foreign matter such as flying gravel. Thus, it is enabled to dispose the starter motor 70 on the front lower side of the internal combustion engine 20, thereby enabling to make the internal combustion engine 2 0 compact as well as lower the center of gravity of the vehicle. [0069]
The mount plate 15 is disposed with a lower pnd of its front wall 15f located below the internal combustion engine 2 0 to protect a lower portion of the internal combustion engine 20 also from flying gravel and others. [0070]
Since the oil pump 80 is disposed in the crankcase 22 at a place near and substantially under the crankshaft 21 and on the rear side of the starter motor 70, provision of the oil pump 80 does not increase the size of the internal combustion engine.

[Reference Signs List]
[0071]
1... Motorcycle,
2... Head tube,
3... Main frame,
4... Down frame,
5... Seat rail,
6... Backstay,
7... Front fork,
8... Front wheel,
9... Pivot plate,
10... Rear fork,
11... Rear wheel,
12... Rear cushion,
13... Fuel tank,
14... Seat,
15... Mount plate,
16... Bolt,
17... Support bolt,
18ru... Upper attaching member,
ISrl... Lower attaching member,
19... Support bolt,
20... Internal combustion engine,
21... Crankshaft,
211... Left crankshaft portion,
21r... Right crankshaft portion,
21w... Crank web,
22... Crankcase,

23... Cylinder block,
24... Cylinder head,
25... Cylinder head cover,
26,.. Intake pipe,
27... Throttle body,
28... Air cleaner,
2 9... Exhaust pipe,
SOL... Left case cover,
3OR... Right case cover, 31... Main bearing, 32... Drive sprocket, 33... Starter driven gear, 34... One-way clutch, 35... AC generator,
3 6... Pump drive gear,
37... Centrifugal oil strainer,
3 8... Nut,
40... Camshaft,
41... Camshaft holder,
42... Driven sprocket,
43... Cam roller chain,
44... Guide roller,
45... Guide roller,
50... Cam-chain tensioning device,
51... Tensioner arm,
52... Pivot bolt,
53... Tensioner roller,
55... Tensioner lifter.

56... Push rod,
57... Guide bore,
58... Guide cylindrical portion,
59... Side wall plate,
60... Oil sump,
61... Control valve,
62... Compression spring,
63... Tensioner bolt,
70... Starter motor,
71... Motor main body,
72... Bearing lid member,
73... Starter drive shaft,
74... Power terminal,
75... Bolt,
76... Intermediate gear shaft,
77... Intermediate gear,
8 0... Oil pump,
81... Pump base plate,
82... Pump housing,
83... Outer rotor,
84... Inner rotor
8 5... Pump drive shaft,
86... Pump driven gear

[Document Name] Scope of Claims [Claim 1]
A starter-motor arrangement structure of an internal combustion engine in which:
a crankshaft is rotatably journaled to a crankcase of the internal combustion engine installed on a motorcycle such that the crankshaft is oriented in a left-right direction,
an endless roller chain is wound between a diive sprocket fitted on the crankshaft and a driven sprocket fitted on a cam shaft of a valve system,
the roller chain is pushed by a pressing member, and
the pressing member is in pressing contact with a push rod inserted and slidably fitted in a guide bore formed in the crankcase,
wherein the push rod is disposed such that a rod axis thereof forms an obtuse angle on a front side in a side view with a cylinder axis of a cylinder standing on the crankcase, and
wherein the starter motor is disposed in a front portion of the crankcase within the obtuse angle formed between the cylinder axis and the rod axis. [Claim 2]
The starter-motor arrangement structure of the internal combustion engine according to claim 1, wherein an oil pump is disposed at a place in the crankcase near and substantially under the crankshaft on a rear side of the starter motor.

[Claim 3]
The starter-motor arrangement structure of tlie internal combustion engine according to claim 1 or 2,
wherein a starter drive gear is disposed on starter drive shaft protruding leftward from a motor main ibody of the starter motor,
wherein a starter driven gear is rotatably journaled to a left shaft portion of the crankshaft, and
wherein an intermediate gear having a large-ciameter gear and a small-diameter gear that are integrally formed is interposed between and in meshing engagement with the starter drive gear and the starter driven gear. [Claim 4]
The starter-motor arrangement structure of the internal combustion engine according to claim 3,
wherein the oil pump is disposed at a position to overlap with the starter driven gear in a side view on a right side of a vertical plane including the cylinder axis. [Claim 5]
The starter-motor arrangement structure of the internal combustion engine according to any one of claims 1 through 4,
wherein a mount plate supporting the internal combustion engine on a vehicle-body frame covers the starter motor that is disposed in a front portion of the crankcase from a front side, and
wherein the mount plate expands at a portion which corresponds to a power terminal protruding on the starter

motor.

Documents:

http://ipindiaonline.gov.in/patentsearch/GrantedSearch/viewdoc.aspx?id=jGAPY3yVtGx4VkeDegD3Xw==&loc=egcICQiyoj82NGgGrC5ChA==

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Patent Number

268710

Indian Patent Application Number

451/CHE/2010

PG Journal Number

38/2015

Publication Date

18-Sep-2015

Grant Date

14-Sep-2015

Date of Filing

22-Feb-2010

Name of Patentee

HONDA MOTOR CO., LTD.

Applicant Address

1-1, MINAMI-AOYAMA 2-CHOME, MINATO-KU, 107-8556, TOKYO

Inventors:

#	Inventor's Name	Inventor's Address
1	KANAE, TAKESHI	C/O HONDA R&D CO., LTD., 4-1, CHUO 1-CHOME, WAKO-SHI, SAITAMA 351-0193
2	KONO, NAOKI	C/O HONDA R&D CO., LTD., 4-1, CHUO 1-CHOME, WAKO-SHI, SAITAMA 351-0193
3	YOKOMORI, TETSUHITO	C/O HONDA R&D CO., LTD., 4-1, CHUO 1-CHOME, WAKO-SHI, SAITAMA 351-0193

PCT International Classification Number

F02N 11/00

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	2009-040233	2009-02-24	Japan