JPH0444428Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a cooling structure for a power unit mounted on a small vehicle such as a motorcycle or a tricycle.

Prior Art and Its Problems A main transmission, which is a V-belt continuously variable transmission in which a V-belt is wound around a driving V-pulley and a driven V-pulley, is arranged adjacent to an engine and divided into a crank case and an auxiliary case. A power unit for a small vehicle is already known, in which the auxiliary transmission is disposed inside the crankcase (for example, Japanese Patent Laid-Open No. 136520/1983). In such a power unit, the V-belt continuously variable transmission is easily affected by heat generated by the engine (radiant heat), and it is desirable to exhaust hot air within the transmission case to the outside.

Means for Solving the Problems The purpose of the present invention is to install a main transmission, which is a V-belt continuously variable transmission in which a V-belt is wound between a driving V-pulley and a driven V-pulley, adjacent to an engine. In a power unit for a small vehicle, which is arranged in a room defined by a crankcase and an auxiliary case, and an auxiliary transmission is arranged inside the crankcase,
The objective is to effectively suppress the influence of engine generated heat on the main transmission.

The purpose of this is to fit the driving V-pulley of the main transmission onto the crankshaft protruding from the crankcase, and to fit the driven V-pulley onto the input shaft of the sub-transmission protruding from the crankcase. In the storage chamber, the main transmission crankcase side wall is insulated, and a space is placed between the side wall of the crankcase and the front and rear portions of the compartment defined by the heat shield and the crankcase are connected to the outside air. This is achieved by providing a communicating vent.

Embodiment Hereinafter, an embodiment of the present invention shown in FIGS. 1 to 3 will be described.

FIG. 1 conceptually shows a power unit 10 for a motorcycle, and a rear wheel RW is driven by a drive chain wrapped around the final output gear (drive sprocket) of the power unit 10. ing. The power unit 10 is the engine 1
2, main transmission 38, and automatic centrifugal clutch 72.
and an auxiliary transmission 84. engine 12
The crankshaft 36 and sub-transmission 84 are housed within the crankcase body 14, and the main transmission 38 and automatic centrifugal clutch 72 are housed within the crankcase cover 16 (in this specification, similar to the crankcase body 14, the crankcase The case cover 16 is also regarded as a crankcase) and the auxiliary case 28.
Further, within the chamber A, a heat shield plate 30 screwed onto the side wall 22 of the crankcase cover 16 at a small interval cooperates with the crankcase cover 16 to form a small compartment B. The crankcase
The wind entering the small compartment B through a vent 20 formed in the front wall 18 of the cover 16 is exhausted to the outside through a vent 24 formed in a side wall 22 at the rear of the crankcase cover 16. It's becoming like that.

FIG. 2 shows the detailed structure of the power unit 10. A driving V pulley 40 of the main transmission 38, which is a V-belt continuously variable transmission, is attached to the end of the crankshaft 36, which extends through the crankcase body 14, the crankcase cover 16, and the heat shield plate 30. It is fitted. The drive V pulley 40 has a fixed face 4 immovably fixed on the crankshaft 36.
6, a movable face 48 that is slidably fitted onto the cylinder 52 that is fitted onto the crankshaft 36, and a fixed plate 42 that is immovably fixed on the crankshaft 36 at a position near the shaft end. A weight 54 is freely housed in a small chamber with a triangular cross section defined by a fixed face 46 and a movable face 48, both of which are shaped like saucers.
It is constructed with these as the main members. The movable face 48 is supposed to freely rotate on the crankshaft 36, but this free rotation is restricted due to the relationship in which the locking piece 44 of the fixed plate 42 engages with the protruding piece 50 of the movable face 48. Fixed face 46, fixed plate 4
2, the movable face 48 also rotates together with the crankshaft 36. Furthermore, while the crankshaft 36 is rotating at a low speed, the weight 54 is in the position shown by the solid line in FIG. 2, but as the rotational speed of the crankshaft 36 increases, the weight 54 is moves away from the crankshaft 36 (in the radial direction) and pushes the fixed plate 42 and the inclined wall of the movable face 48, so that the movable face 48 slides on the cylinder 52 and is moved toward the fixed face 46. This means that the crankshaft 3
6 increases, the belt wrapping radius of the drive V-pulley 40 increases, which means that the gear ratio of the main transmission 38 becomes smaller (small gear ratio → rear wheel rotation speed Big).

A driven V-pulley 60 of the main transmission 38 is connected to a driven shaft 58 (the driven shaft 58 is integrated with an input shaft 86 of a sub-transmission 84 described later) that extends into the room A through the crankcase cover 16 and the heat shield plate 30. ) with an automatic centrifugal clutch 72. The driven V-pulley 60 has a fixed face 64 fixedly fixed on an inner cylinder 62 which is rotatably fitted onto the driven shaft 58 via a pair of bearings, and a fixed face 64 which is movable in the axial direction on the inner cylinder 62 ( drive of a movable face 68 immovably fixed on an outer cylinder 66 which is fitted against relative rotation (within a limited range of movement) and an automatic centrifugal clutch 72 immovably fixed on an inner cylinder 62; Board 7
4 and a compression coil spring 70 interposed between the movable face 68 and surrounding the outer cylinder 66 as the main members.

A V-belt 56 is wound between the driving V-pulley 40 and the driven V-pulley 60, and the crankshaft 3
The rotation of the drive V pulley 40 that rotates integrally with V
It is transmitted to the driven V-pulley 60 via the belt 56. As the rotational speed of the crankshaft 36 increases, the belt wrapping radius of the driving V-pulley 40 increases as described above, and accordingly, the movable face 6 of the driven V-pulley 60 resists the elastic force of the compression coil spring 70.
8 is moved to the automatic centrifugal clutch 72 side, and the driven V
The belt winding radius of the pulley 60 becomes smaller (speed ratio is smaller).

The automatic centrifugal clutch 72 includes a drive plate 74 fixed immovably on the inner cylinder 62, a bowl-shaped driven plate 82 fixed immovably on the driven shaft 58, and a pin 76 that swings on the drive plate 74. The main member is a freely supported weight 78.

While the rotational speed of the crankshaft 36 is sufficiently low and therefore the rotational speeds of the inner cylinder 62 and drive plate 74, which always rotate together with the driven V-pulley 60, are sufficiently low, the clutch shoe 80 of the weight 78 is However, when the rotational speed of the drive plate 74 increases to a certain extent, the weight 7 moves around the pin 76 as a fulcrum.
8 swings in the direction away from the driven shaft 58 (radial direction), and the clutch shoe 80 of the weight 78 is strongly pressed against the driven plate 82, resulting in a clutch connected state. As a result, the drive plate 74 and the driven plate 82 rotate integrally, and therefore the driven shaft 58, which is integral with the driven plate 82, rotates.

The sub-transmission 84 is housed within the crankcase body 14. The input shaft 86 of the sub-transmission 84 is a hollow body formed integrally with the driven shaft 58, and is supported by the crankcase body 14 in a fitting relationship with the output shaft 100 via bearings 90, 92. The input shaft 86 integrally has an input gear 88.
8 meshes with an intermediate gear 96 that is integrated with an intermediate shaft 94. Further, another intermediate gear 9 integrated with the intermediate shaft 94
8 meshes with a gear 102 integrated with the output shaft 100.

Therefore, in the sub-transmission 84, the input shaft 86
The rotation of the driven shaft 58 is decelerated in two stages by the meshing relationship between the input gear 88 and the intermediate gear 96, and between the intermediate gear 98 and the gear 102.

A final output gear (driving sprocket) 104 is fixed to the end of the output shaft 100 protruding from the crankcase body 14, and a final output gear (driving sprocket) 104 is connected between the final output gear (driving sprocket) 104 and the driven sprocket of the rear wheel RW. A drive chain 106 is wrapped around it.

Therefore, the output of the engine 12 is as follows: crankshaft 36 → driving V pulley 40 → V belt 56 → driven V
Pulley 60 → automatic centrifugal clutch 72 → input shaft 86
→ Intermediate shaft 94 → Output shaft 100 → Drive chain 10
The signal is transmitted to the rear wheel RW by a transmission mechanism 6.

The present embodiment is constructed as described above, and inside the chamber A defined by the crankcase cover 16 and the auxiliary case 28, a shield is placed at a small distance from the side wall 22 of the crankcase cover 16. A heat plate 30 is provided, and a crankcase cover 16 and a heat shield plate 3
Since the small compartment B is partitioned by 0, the air layer within the small compartment B has a heat insulating effect,
Coupled with the fact that the air layer between the crankcase body 14 and the crankcase cover 16 functions in the same way, this effectively prevents the heat emitted from the engine 12 from being transmitted to the main transmission 38 as radiant heat. be done. This heat shielding effect is due to the fact that while the vehicle is running, wind enters into the small compartment B from the vent 20 formed in the front wall 18 of the crankcase cover 16, and the side wall 18 of the crankcase cover 16
It is further ensured that the air is discharged to the outside through a vent hole 24 formed in 2 (see arrow C).

Another advantage of arranging the heat shield plate 30 along the crankcase cover 16 is that dust entering the sub-compartment chamber B through the vents 20 and 24 can be removed from the main transmission 38 and the automatic centrifugal clutch. 72 is stored in the space.

Furthermore, the crankcase and driven V pulley 6
By adopting a structure in which an automatic centrifugal clutch 72 is located between
miniaturization is achieved.

Effects of the invention As is clear from the above explanation, the V
The main transmission, which is a belt-driven continuously variable transmission, is located adjacent to the engine in a room defined by a crankcase and an auxiliary case, and the auxiliary transmission is located inside the crankcase. A cooling structure for a vehicle power unit in which the driving V-pulley of the main transmission is fitted onto the crankshaft protruding from the crankcase, and the driven V-pulley is fitted onto the input shaft of the sub-transmission protruding from the crankcase. In the main transmission storage chamber, a heat shield plate is provided at a distance between the main transmission and the crankcase side wall, and the heat shield plate and the crankcase are partitioned. A cooling structure has been proposed in which vents communicating with the outside air are provided at the front and rear of a defining chamber, respectively.

In such a structure, the air in the compartment defined by the heat shield plate and the crankcase has a heat insulating effect, and this air is sequentially replaced with outside air through the front and rear vents, which reduces engine power generation for the main transmission. The effect of heat is effectively suppressed. In addition, dust entering the defining chamber through the vent is blocked by the heat shield plate, and the influence of dust on the main transmission, which is a V-belt continuously variable transmission, is sufficiently reduced.

[Brief explanation of the drawing]

Fig. 1 is a conceptual diagram of a power unit for a motorcycle that employs a cooling structure according to an embodiment of the present invention, Fig. 2 is a detailed sectional view of the power unit, and Fig. 3 is a crankcase adopted with the cooling structure. - It is a front view of the cover. 10...power unit, 12...engine,
14...Crankcase body, 16...Crankcase cover, 18...Front wall, 20...Vent hole, 22...Side wall, 24...Vent hole, 26...Rear wall, 28...Auxiliary case, 30... Heat shield plate, 3
2, 34...opening, 36...crankshaft, 38...
... Main transmission, 40 ... Drive V pulley, 42 ... Fixed plate, 44 ... Locking piece, 46 ... Fixed face,
48...Movable face, 50...Protrusion piece, 52...
Tube, 54... Weight, 56... V-belt, 58...
Driven shaft, 60... Driven V pulley, 62... Inner cylinder,
64...Fixed face, 66...Outer cylinder, 68...
Movable face, 70... Compression coil spring, 72...
...Automatic centrifugal clutch, 74...Drive plate, 76...
Pin, 78... Front wall, 80... Clutch/shew, 82... Driven plate, 84... Sub-transmission, 86...
...Input shaft, 88...Input gear, 90,92...Bearing, 94...Intermediate shaft, 96,98...Intermediate gear,
100... Output shaft, 102... Gear, 104...
Final output gear (drive sprocket), 106...
drive chain.

Claims (1)

[Scope of Claim for Utility Model Registration] A main transmission, which is a V-belt transmission type continuously variable transmission in which a V-belt is wound between a driving V-pulley and a driven V-pulley, is located adjacent to an engine with a crankcase and an auxiliary case. In a power unit for a small vehicle in which the auxiliary transmission is located in a room defined by The driven V-pulley is fitted onto the input shaft of the auxiliary transmission protruding from the crankcase, and the main transmission and the crankcase side wall are isolated from each other in the main transmission storage chamber, and the gap between the main transmission and the crankcase side wall is closed. A power unit for a small vehicle, characterized in that heat shield plates are provided at intervals between the heat shield plates and the crankcase, and vents communicating with outside air are provided at the front and rear parts of a compartment defined by the heat shield plate and the crankcase, respectively. cooling structure.