JPH0375736B2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention provides a transmission that is disposed within a crankcase behind a crankshaft that is disposed in the width direction of a vehicle body, and one end of the main shaft of this transmission. This invention relates to a multi-cylinder engine for motorcycles equipped with a clutch.

(Prior Art) In engines used in motorcycles, a transmission is disposed within the crankcase to reduce the size of the engine unit. A clutch is disposed at one end of the main shaft of the transmission.

For example, there is a multi-cylinder engine that is equipped with a crankshaft that extends in the width direction (sideways) of the vehicle body and a transmission located behind the crankshaft. In this case, conventionally, a reduction gear for transmitting the rotation of the crankshaft to the clutch housing was provided at a position protruding from a bearing at one end of the crankshaft, and the clutch was arranged so as to protrude to the side of the engine. This has caused a problem in that the overall width of the engine increases.

On the other hand, in some in-line multi-cylinder engines with horizontal crankshafts, in order to reduce the engine width, gears are formed on the crank web of the crankshaft, and the crank web itself is used as a small reduction gear.

However, in this case, it becomes impossible to directly mesh the large diameter reduction gear with the reduction small gear,
Furthermore, since the small reduction gear cannot be made small in diameter, the large reduction gear has a large diameter. For this reason, in the past, an intermediate shaft was interposed between the crankshaft and the main shaft of the transmission, and the rotation of the reduction gear was transmitted via the intermediate shaft to a clutch disposed at one end of the main shaft to reduce the speed. As a result, the configuration becomes complicated and the large reduction gear becomes large.
It was also difficult to downsize the engine.

(Objective of the Invention) The present invention was made in view of the above circumstances, and it is an object of the present invention to provide a multi-cylinder engine that reduces the amount of protrusion of the clutch in the direction of the crankshaft, is suitable for downsizing the entire engine, and has a simple structure. The purpose is to provide

(Structure of the Invention) According to the present invention, the object is to provide a crankshaft disposed in the width direction of the vehicle body, a transmission disposed behind the crankshaft in the crankcase, and one end of the main shaft of the transmission. and a clutch disposed on the crankshaft, the rotation of the crankshaft being transmitted to the clutch by means of a small reduction gear provided on the crankshaft and a large reduction gear provided on the housing of the clutch that meshes with the small reduction gear. In the multi-cylinder engine, the reduction gear is disposed between a bearing at the end of the crankshaft and a crank web closest to the bearing, and the radius of the reduction gear is smaller than the maximum radius of the crank web. This is achieved by a multi-cylinder engine for motorcycles that is characterized by the following.

(Embodiment) Fig. 1 is a side view of a motorcycle to which an embodiment of the present invention is applied, Fig. 2 is a side view of its engine, and Fig. 3 is a sectional view of the motorcycle near the - line.

In FIG. 1, reference numeral 10 is a water-cooled overhead camshaft front and rear V-type engine. This engine 10 is
Its front part is fixed to the down tube 12, and its rear part is fixed to the lower end of the main tube 14, respectively. Main tube 14 and down tube 12
The upper end of the steering head pipe 16 is fixed to a steering head pipe 16, and a front fork 18 is attached to this head pipe 16. 20 is a front wheel attached to this front fork 18, and 22 is a handlebar. 24 is a fuel tank installed on the main pipe 14 behind the head pipe 16;
6 is the driver's seat behind it, and 28 is the rear wheel.
Further, 30 is a radiator attached to the down tube 12, and cools the cooling water circulating within the engine 10.

Next, the engine 10 will be explained based on FIGS. 2 and 3. This engine 10 includes a front bank 32 that tilts forward and a rear bank 34 that tilts backward. The crankcase 36 is divided into upper and lower parts, and is formed of an upper case 36A and a lower case 36B. Upper/lower case 36
Between the split surfaces A and 36B, a balance weight 38, a crankshaft 40, a main shaft 42, and a subshaft 44 are rotatably held in the vehicle width direction in order from the front.
The balance weight 38 rotates at the same speed in the opposite direction to the crankshaft 40, and has the function of mainly absorbing the primary vibration of the crankshaft 40. Main shaft 42, sub shaft 44
A large number of transmission gear groups are provided, and a known constant-mesh transmission 46 is formed by these gears. That is, the transmission 46 is disposed within the crankcase 36.

This engine 10 includes four cylinders. The crankshaft 40 has a crank pin 4 with a 180° phase difference.
8a, 48b and four crank webs 50a~
50d, and three journal parts 52 (52a, 5
2b, 51c). Each crank pin 48 has a piston 54 (54a, 54) of the rear bank 34.
Connecting rod 56 (56a, 56b) connecting b)
is on the left side, and connecting rod 60 (60a,
60b) are respectively attached to the right side. As a result, the front bank 32 is displaced to the right with respect to the centerline of the engine 10, and the left bank 34 is displaced to the left.

The crankshaft 40 is connected to the upper and lower cases 36A, 3
Between 6B, plain bearings 51 (51a, 51b, 51
It is held at three journal parts 52 via c). A known flywheel magnet 62 is attached to the left protruding end of the crankshaft 40, and a sprocket 64 is formed at the right protruding end.

66 is an intermediate shaft disposed within the narrow angle of each bank 32,34. This intermediate shaft 66 is equipped with a sprocket 68, which is connected to the sprocket 6 of the crankshaft 40.
Through a chain 70 wound between 4 and 4,
It is rotated by a crankshaft 40. Each bank 3
2 and 34 are two overhead cams 72 (72
a, 72b), and 74 (74a, 74b).
The camshaft 72 of the front bank 32 is driven by the intermediate shaft 66 via a cam chain 76 disposed on the opposite side to the deflection direction (right side) of the front bank 32 . The camshaft 74 of the rear bank 34
It is driven by the intermediate shaft 66 via a cam chain 78 disposed on the side opposite to the direction of deflection (left side). The camshafts 72, 74 are connected to the chains 70, 76,
78, it rotates at half the speed of the crankshaft 40, and opens and closes a known intake valve 80 and an exhaust valve 82 (only one of which is shown in FIG. 2).

84 is a wet multi-disc clutch, which is connected to the transmission 4.
It is attached to the right end of the main shaft 42 of No. 6. A large reduction gear 88 is attached to the housing 86 of this clutch 84.
is fixed. On the other hand, a reduction gear 90 is fixed to the crankshaft 40 so as to be located between a plain bearing 51c that holds the journal portion 52c on the clutch 84 side and the crank web 50d closest to the bearing 51c. This gear 90 has a radius smaller than the maximum radius of the crank web 50, and meshes with the large reduction gear 88. That is, the clutch 84 passes through a vertical plane including the flat bearing 51c in the longitudinal direction, faces from the right side of the crankcase 36 to the right, and is housed in a clutch housing chamber surrounded by a clutch cover. In FIG. 3, a gear 92 fixed to the crankshaft 40 at a position substantially symmetrical to the reduction gear 90 drives the balance weight 38 (FIG. 2).

A sprocket 94 is fixed to the left end of the subshaft 44, and this sprocket 94 and the rear wheel 28
A drive chain 98 is wound around the sprocket 96.

Next, the operation of this embodiment will be explained. crankshaft 4
0 rotation, the intermediate shaft 66, cam shafts 72, 74
rotates at a predetermined timing, and the intake/exhaust valves 80, 8
2 opens and closes. Further, the rotation of the crankshaft 40 is transmitted to the clutch housing 86 via small and large reduction gears 90 and 88, and the transmission 46 and sprocket 9
4, transmitted to the rear wheels 28 via the chain 98.

Since the reduction pinion gear 90 is fixed between the journal part 52c at one end of the crankshaft 40 and the crank web 50d closest to this, the reduction gear pinion 90 is fixed between the journal part 52c at one end of the crankshaft 40 and the crank web 50d closest to the journal part 52c. Compared to the engine, the clutch 84 can be placed closer to the center of the engine 10, and the amount of protrusion of the clutch 84 can be reduced. Furthermore, when this reduction gear is provided on the crank web 50d, the radius cannot be made smaller than the maximum radius of the crank web 50, so it is impossible to reduce the diameter of this reduction gear, and the large reduction gear of the clutch becomes large. In addition, it becomes necessary to transmit the rotation of the reduction gear to the clutch (reduction large gear) at one end of the main shaft via the intermediate shaft, making the structure complex and difficult to miniaturize. However, according to this embodiment, there is no such inconvenience, and it is possible to have a simple configuration and promote miniaturization of the engine 10.

(Effects of the Invention) As described above, the present invention arranges a reduction gear with a radius smaller than the maximum radius of the crank web between the bearing at the end of the crankshaft and the crank web closest to this bearing, and Since the large reduction gear is meshed with the small reduction gear, the amount of protrusion of the clutch can be reduced and the engine can be made smaller. Further, unlike the case where a small reduction gear is provided on the crank web, there is no need for the large reduction gear to become large or to provide an intermediate shaft, so the structure is simple and the engine can be made smaller.

[Brief explanation of drawings]

FIG. 1 is a side view of a motorcycle using an embodiment of the present invention, FIG. 2 is a side view of an engine, and FIG. 3 is a sectional view of the area near the - line. 10...Engine, 36...Crankcase,
42...Main shaft, 46...Transmission, 50...Crank web, 51...Flat bearing, 84...Clutch,
86...Clutch housing, 88...Reduction large gear, 90...Reduction small gear.

Claims (1)

[Claims] 1 A crankshaft disposed in the width direction of the vehicle body, a transmission disposed behind the crankshaft inside the crankcase, and a clutch disposed at one end of the main shaft of the transmission. In a multi-cylinder engine for a motorcycle, the rotation of the crankshaft is transmitted to the clutch by a reduction gear provided in the housing of the clutch and a reduction large gear provided in the housing of the clutch that meshes with the reduction gear. A multi-cylinder engine for a motorcycle, characterized in that the reduction gear is disposed between a bearing at a shaft end of the engine and a crank web closest to the bearing, and the radius of the reduction gear is smaller than the maximum radius of the crank web.