Title of Invention

"A VEHICLE POWER UNIT"

Abstract

[Problem] To provide a power unit that unifies an internal combustion engine and a transmission system used in a small type motorcycle etc., and particularly a narrow power unit having side parts of the power unit projecting into space inside spokes of a wheel. [Means Of Solution] A vehicle power unit 1 having an axle 13 acting as an output shaft of a transmission system 3 rotatably supported by a power unit casing 6 unifying an internal combustion engine 2 and the transmission system 3, wherein spokes 16 of a wheel 14 fixed to the axle 13 run from a central part close to the axle of the spokes 16 to an outer part close to a tire of the axle 13, and curve significantly in a direction approaching the vehicle power unit 1, the vehicle power unit casing 6 or a cover member 26 of the power unit casing 6 are formed swelling in a direction adjacent to the curved spokes 16 of the wheel 14, and a generator 22 is housed in the swollen part 6a of the power unit casing 6 or the swollen part of the cover member 26.

Full Text

Technical Field: The present invention relates to a vehicle power unit. [Related Art] As is exemplified in Japanese Patent laid-open publication No. Hei 1-244995, a wheel is arranged on the right side of a power unit of a scooter type motorcycle, and spokes of the wheel are formed significantly curved in a rightward direction. A power unit case projects into space inside these spokes, and by arranging a transmission system inside the projecting sections, both the wheel and the power unit case can accordingly be made compact. [Problems To Be Solved By The Invention] With the conventional power unit described above, by making effective use of the space inside curved spokes of the wheel, a transmission system further back than the crank shaft becomes close to a right side wheel, and even if the extent to which the rear left side part of the power unit case projects can be reduced, since a generator is provided on a left side of the crank shaft the extent to which the left side part of the crank shaft of the power unit case projects can not be reduced which means that it is not possible to make the overall width of the power unit sufficiently narrow. [Means Of Solving The Problems] Accordingly, there is provided a vehicle power unit having an axle acting as an output shaft of a transmission system rotatably supported by a power unit casing unifying an internal combustion engine and the transmission system, wherein spokes of a wheel fixed to the axle run from a center part close to the axle of the spokes to an outer part close to a tire of the axle, and curve significantly in a direction approaching the vehicle power unit; characterized in that the vehicle power unit casing or a cover member of the power unit casing are formed swelling in a direction adjacent the curved spokes of the wheel; and a generator is housed in the swollen part of the power unit casing or the swollen part of the cover member. Since the invention disclosed in claim 1 has the above described construction, a generator is arranged in the swollen part of the vehicle power unit casing or the swollen part of a cover member of the power unit projecting into space inside curved spokes of the wheel, the extent to which the vehicle power unit projects to the side opposite the side on which the wheel is located is reduced, the overall width of the vehicle power unit is reduced, and it is possible to miniaturize the vehicle power unit. Thus, in the case where the vehicle is a motorcycle, the bank angle can be made large and handling is improved. [0006]Further, by constructing the invention as disclosed in claim 2, a generator arranged in the swollen part of the power unit or the swollen part of the power unit cover member is separated from a transmission system exposed to a lubricating oil atmosphere by the extent of the airtight member, and the generator is not contaminated by the lubricating oil, giving double protection. The front end of the axle is supported by the swollen part of the power unit casing or the swollen part of the cover member, via a projecting end of the airtight member encapsulating the transmission system, which means that the projecting end of the airtight member is sufficiently strengthened by the swollen part. [0007]Further, by constructing the invention as disclosed in claim 3, brake reactive force received from the brake drum of the wheel acts on the swollen part of the power unit casing or the swollen part of the cover member that are rapidly separated from the axle, which means that such a large load force does not act, and the brake reactive force is reliably secured. [Brief Description Of The Accompanying Drawings] Fig. 1 is a vertical cross section of a power unit taken through the essential parts of an internal combustion engine of a power unit. Fig. 2 is a vertical cross section cut along line II-II of Fig. 1 Fig. 3 is a vertical cross section cut along line Ill-Ill of Fig. 1 [0008| [Embodiment Of The Invention] An embodiment of the present invention shown in Fig. 1 to Fig. 3 will now be described below. [0009] As shown in Fig. 1, a power unit 1 used with a scooter type motorcycle, not shown, unifies an internal combustion engine 2 and a power unit case 6 , and the cylinder head 4 and cylinder block 5 of the internal combustion engine 2 are joined together with bolts, also not shown. [0010] As shown in Fig. 2 and Fig. 3, a power unit case 6 unifying the crankcase of the internal combustion engine 2 and a transmission case of the transmission system 3 in a longitudinal direction of the motorcycle is divided in a widthwise direction into a left power unit case 6a, a central power unit case 6b, and a right power unit case 6c. These three power unit case components are also joined together with bolts, not shown. Also, a cylinder block 5 and the power unit case 6 are joined together by bolts, not shown. [0011] A piston 7 slidably engaged with the cylinder block 5 of the internal combustion engine 2 is linked to a crankshaft 8 pivoting in the power unit case 6, via a connecting rod 9, and the crankshaft 8 is rotatably driven by reciprocating movement of the piston 7. [0012] The transmission system 3 comprises a centrifugal clutch 10, a change clutch 11, geared transmission 12, and an shaft 13 acting as the output shaft of the geared transmission 12. A hub 15 of a rear wheel 14 is integrally fastened to the axle 13, and spokes 16 extending in a radial direction from the hub 15 curve significantly to the left. A 10wer cushion bracket 18 of a left side shock absorber, not shown, is connected to the right end of the axle 13 via a bearing 17. [0013] A reduction drive gear 8a integral with the crankshaft 8 meshes with a reduction driven gear 10b integral with the primary shaft 10a of the centrifugal clutch 10, and an output gear 10d integral with an output shaft 10c of the centrifugal clutch 10 meshes with an input gear 1 Ib integral with an input member 1 la of the change clutch 11. [0014] A main shaft 1 Ic of the change clutch 11 is connected to the axle 13 acting as a final shaft via a reduction gear train 19 of the geared transmission 12, a counter shaft 20 and a final gear 21. The shaft 13 is rotatably driven at a specified reduction ratio by selective meshing of the reduction gear train 19. [0015] A rotor 22a of a generator 22 is integrally engaged with the right end of the crankshaft 8, and a stator 22b of the generator 22 is integrally attached to the right power unit case 6b of the power unit case 6. |0016] A big end 25 acting as a pivotal attachment of the crankshaft 8 and the piston 7, the centrifugal clutch 10 and the change clutch 11 are arranged inside a left side crankcase chamber 23 surrounded by the left power unit case 6a and the central power unit case 6b, while a reduction drive gear 8a of the crankshaft 8, a reduction driven gear 10b of the centrifugal clutch 10 and the geared transmission 12 are arranged inside a right side crankcase chamber 24 surrounded by the ventral power unit case 6b and the right power unit case 6c. [0017] A cover 26 formed so as to swell as it approaches curved spokes 16 of the shaft 13 is integrally attached to the right side of the right power unit case 6c of the power unit case 6. An axle pivot tube sectioned of the right power unit case 6c is fitted into a hole 26a of the swollen cover 26, and the generator 22 is encapsulated by the right power unit case 6c and the swollen cover 26. [0018] A brake drum 27 is formed in the left side of the rear wheel 14, a brake shoe 28 is arranged relative to an inner peripheral surface of the brake drum 27, and as shown in Fig. 2, the brake shoe 28 is slidably supported by a brake cam lever 30 via an anchor pin 29. If the brake cam lever 30 connected to the brake lever, not shown, is slid in a braking direction, the brake shoe 28 is pressed against or separated from the inner peripheral surface of the brake drum 27 by a cam, also not shown. [0019] Because the embodiment shown in Fig. 1 to Fig. 3 has the above described construction, if the internal combustion engine 2 is started the crankshaft 8 rotates, the centrifugal clutch 10 is driven to rotate, the centrifugal clutch 10 is engaged when it reaches a specified rotational speed and the input member 1 la of the change clutch 11 is also driven to rotate. [0020] If a clutch lever and change lever, not shown, are actuated, the geared transmission 12 selects a specified transmission ratio accompanying engagement of the change clutch 11, and the axle 13, namely the rear wheel 14, is driven to rotate, and in this way, it is possible to make the scooter type motorcycle, not shown, run. [0021] Also, since a crank outer 8b of the crankshaft 8, the big end 25, the centrifugal clutch 10 and the change clutch 11 are arranged compactly inside a left side crankcase chamber 23 surrounded by the left power unit case 6a and the central power unit case 6b so as not to overlap each other, the width of the left side crankcase chamber 23 is narrow. Moreover, since the reduction drive gear 8a and the generator 22 are arranged along the 10ngitudinal direction,of the crankshaft, and stored in curved space inside the spokes of the rear wheel 14 via the swollen cover 26, and the geared transmission 12 is also stored in curved space inside the spokes 16 of the rear wheel 14 via the right power unit case 6c, the width of the power unit case 6 becomes narrow and it can be formed in a compact manner. [0022] Because the width of the power unit case is narrow, it is possible to have a large bank angle with this embodiment even if the bottom of the power unit case 6 is not widely separated from the road surface and even if the crank shaft is arranged 10wer than the center of the axle, as shown in Fig. 1, which leads to excellent handling of a scooter type motorcycle. [0023] A large brake reactive force applied to the brake shoe 28 is secured by the swollen cover 26, and the swollen cover 26 is attached to the right power unit case 6c at a point, not shown, widely separated from the axle 13. This means that the brake reactive force does not place any 10ad on the power unit case 6, giving a firm and stable riding feel. [0024] The generator 22 is disengaged from the geared transmission 12 exposed to a lubricating oil atmosphere by the right power unit case 6c, and encapsulated from the outside of the vehicle by the right vehicle case 6c and the swollen cover 26. This means that the generator 22 is not contaminated by lubricating oil or dust. [0025] Further, the left end of the axle 13 is pivotally supported at the central power unit case 6b, the central part of the axle 13 is pivotally supported at the axle pivoting tube section 6d of the right power unit case 6c and the swollen cover 26, and the right end of the axle 13 is pivotally supported at the 10wer cushion bracket 18. This means that the rear wheel 14 is firmly and stably supported by the axle 13. [Description Of The Numerals] 1 power unit 2 internal combustion engine 3 transmission system 4 cylinder head 5 cylinder block 6 power unit case 7 piston 8 crankshaft 9 connecting rod 10 centrifugal clutch 11 change clutch 12 geared transmission 13 axle 14 rear wheel 15 hub 16 spoke 17 bearing 18 lower cushion bracket 19 reduction gear train 20 counter shaft 21 final gear 22 generator 23 left crankcase chamber 24 right crankcase chamber 25 big end 26 swollen cover 27 brake drum 28 brake shoe 29 anchor pin 30 brake cam lever WE CLAIM: 1. A vehicle power unit (1) having an axle (13) acting as an output shaft of a transmission system (3) rotatably supported by a power unit casing (6) unifying an internal combustion engine (2) and the transmission system (3), wherein spokes (16) of a wheel fixed to the axle (13) run from a center part close to the axle of the spokes to an outer part close to a tire of the axle, and curve significantly in a direction approaching the vehicle power unit (1); characterized in that the vehicle power unit casing (6) or a cover member of the power unit casing are formed swelling in a direction adjacent the curved spokes of the wheel; and a generator (22) is housed in the swollen part of the power unit casing (6)or the swollen part of the cover member(26). 2. The vehicle power unit (1) as claimed in claim 1, wherein an airtight member for encapsulating the said transmission system (3) encloses the axle and protrudes into a central part of the wheel spokes, and accompanying the axle pivoting on the protruding end part of the airtight member, the protruding end part of the airtight member penetrates the swollen part of the power unit casing (6) or the swollen part of the cover member (26) and is supported on the swollen part. 3. The vehicle power unit (1) as claimed in claim 2, wherein a brake drum (27) is formed at an inner central part of the said wheel spokes, and a brake shoe (28) of the wheel is supported by the swollen part of the power unit casing (6) or the swollen part of the cover member (26). 4. A vehicle power unit substantially as hereinbefore described with reference to the accompanying drawings.

Documents:

849-del-1999-abstract.pdf

849-del-1999-claims.pdf

849-del-1999-correspondence-others.pdf

849-del-1999-correspondence-po.pdf

849-del-1999-description (complete).pdf

849-del-1999-drawings.pdf

849-del-1999-form-1.pdf

849-del-1999-form-13.pdf

849-del-1999-form-19.pdf

849-del-1999-form-2.pdf

849-del-1999-form-3.pdf

849-del-1999-form-4.pdf

849-del-1999-form-5.pdf

849-del-1999-gpa.pdf