JPH04257785A - Power transmission device for motorcycle - Google Patents

Abstract

PURPOSE:To ensure sufficient minimum ground height and to shorten the longitudinal length of an engine by arranging an intermediate shaft and an output shaft above a straight line extending in the longitudinal direction of a car body and intercoupling a crank shaft and an input shaft and locating an engine mounting part below the straight line. CONSTITUTION:In a power transmission device for a motor bicycle, a V-belt 52 is run around and between a variable pulley 41 on the left side of a crank shaft 23 a variable pulley 48 at the left end part of an input shaft 24. A gear 24a at the right end of the input shaft 24 is engaged with a gear 25a of an intermediate shaft 25, and a gear 25b on the right side of the gear 25a of the intermediate shaft 25 is engaged with a gear 26a of an output shaft 26. A V-belt or a chain is run around and between a pulley 26b on the right side of the output shaft 26 and the pulley of the axle of a rear wheel. Since the intermediate shaft 25 and the output shaft 26 are arranged above a straight line L extending in the longitudinal direction of a car body and interconnecting the crank shaft 23 and the input shaft 24, an engine is not protruded downward. Thus, even in the case of structure wherein an engine mounting part A is located below the straight line L, the longitudinal length of an engine can be shortened while ensuring sufficient minimum ground height.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power transmission device for a motorcycle.

0002

2. Description of the Related Art In motorcycles, the rotation of the engine's crankshaft is decelerated and transmitted to the output shaft via an input shaft and an intermediate shaft. By the way, since motorcycles are small and limited in size, it is desirable for the engine to be small as well. Therefore, the applicant first arranged the intermediate shaft above the straight line in the longitudinal direction of the vehicle body connecting the crankshaft and the input shaft, and the output shaft below, that is, the intermediate shaft and the output shaft were arranged substantially vertically, and the engine We have proposed a power transmission device for motorcycles that reduces the front and rear dimensions of the vehicle.

0003

However, in such a power transmission device, since the output shaft is disposed below the straight line, there is a possibility that the engine bulges downward and the minimum ground clearance becomes low. In particular, an engine mounting portion is often provided at the bottom of the engine, and such a structure further reduces the minimum ground clearance.

0004

Means for Solving the Problems In order to solve the above problems, the present invention provides a power transmission device for a motorcycle that decelerates the rotation of the crankshaft of an engine via an input shaft and an intermediate shaft and transmits the rotation to an output shaft. The intermediate shaft and the output shaft are arranged above a straight line in the longitudinal direction of the vehicle body connecting the crankshaft and the input shaft, and an engine mounting portion is provided below the straight line.

[0005]

[Operation] Since the intermediate shaft and the output shaft are arranged above the straight line in the longitudinal direction of the vehicle body that connects the crankshaft and the input shaft, the engine does not bulge downward. Therefore, even with a structure in which the engine mounting portion is provided below the straight line, a sufficient minimum ground clearance can be ensured.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described below with reference to the accompanying drawings. First, an overview of a motorcycle will be explained using FIG. 1.

This motorcycle is a folding type motorcycle, and in the figure, 1 is a rear frame composed of a pair of left and right frame members 2, 2, and 3 is a left and right frame that is movable rearward with respect to the rear frame 1. A main frame composed of a pair of frame members 4, 4 is shown.

A front fork 6 is provided at the front of the vehicle body, and the front fork 6 supports the front wheel 7. A handle holder 8 that can be folded backward is provided at the upper front of the vehicle body. A handlebar 9 is provided at the upper end.

A rear wheel 13 is provided at the rear of the rear frame 1 via an axle 12, and an engine E is disposed at the bottom of the rear frame 1 (the support structure for the engine E will be described later). A fuel tank 15 is disposed between the frame members 4, 4, and a seat 17 is disposed above the frame members 4, 4 via links 16, 16 which can be folded forward.

Next, the power transmission device will be explained in detail below. Figure 2 is a left side view of the engine, Figure 3 is a longitudinal sectional view of the engine, and Figure 4
5 is an internal development view of the engine, FIG. 6 is a view taken from arrow 6 in FIG. 4, and FIG. 7 is a view taken from arrow 7 of FIG. 4.

[0011] As shown in FIG. 3, the engine E
, B to the rear frame 1.

In the figure, 20 is a crankcase, and this crankcase 20 consists of a left case 21 and a right case 22. Inside the crankcase 20, a crankshaft 23, an input shaft 24, an intermediate shaft 25, and an output shaft 26 are arranged in parallel. and rotatably.

A cylinder 28 is provided in the upper part of the crankcase 20, a piston 29 is slidably provided in the cylinder 28, and the piston 29 and the crankshaft 2
3 are connected by a connecting rod 30.

A mounting portion 31 is provided at the right end of the crankshaft 23.
is attached, and the inner end of the flywheel 32 is fitted to the outer periphery of this attachment portion 31. Also, there is an ACG inside the flywheel 32.
33 is provided, and a fan 35 is attached to the side surface of the flywheel 32 via bolts 34.

A worm wheel 38 is formed on the left side of the ACG 33 of the crankshaft 23, and this worm wheel 38 is meshed with a worm 40 of the rotating shaft 39. The rotation shaft 39 drives the oil pump P provided in front of the crankcase 20, and this rotation shaft 39 is connected to the small diameter portion 3.
The small diameter part 39a and the large diameter part 39b are connected by engaging the concave and convex parts 39c and 39d.

A variable pulley 41 is provided on the left side of the crankshaft 23, and the variable pulley 41 has a dish-shaped fixed face 41a fitted to the end of the crankshaft 23, and a fixed face 41a that is attached to the crankshaft so as to face the fixed face 41a. 23, and a dish-shaped movable face 41b provided to be slidable in the axial direction on 23. The movable face 41b is attached to the crankshaft 23 parallel to the axis and slidable. A plurality of weight rollers 42 are provided on the back side of the movable face 41b, and the weight rollers 42 are attached to the movable face 41b.
and a lamp plate 44 provided to cover the rear surface of the lamp plate 44.
hold it.

The lamp plate 44 is held in place by a sleeve 45 and a nut 46, and a spring (not shown) is disposed between the lamp plate 44 and the movable face 41b to keep the movable face 41b at all times. It is biased towards the fixed face 41a side.

On the other hand, a variable pulley 48 is provided at the left end of the input shaft 24, and the variable pulley 48 has a dish-shaped fixed face 48a fixed to the input shaft 24, and a fixed face 48a that is slidable and rotatable on the input shaft 24. It consists of a movable face 48b that can be freely provided.

A fan 48c is provided on the movable face 48b.
Further, a spring 50 is provided between the movable face 48b and the spring receiver 49 to always urge the movable face 48b toward the fixed face 48a.

A V-belt 52 is hung between the variable pulley 48 and the variable pulley 41, and a starting clutch 54 is provided on the input shaft 24 on the distal end side of the variable pulley 48.

A gear 24a is provided at the right end of the input shaft 24,
This gear 24a meshes with a gear 25a provided on the intermediate shaft 25. A gear 25b is provided on the right side of the gear 25a of the intermediate shaft 25, and this gear 25b meshes with the gear 26a of the output shaft 26. A pulley 26b is provided at the right end of the output shaft 26, and a pulley (26b) provided on the axle of the rear wheel 13 (
A V-belt or a chain (not shown) is hung between the two parts (not shown).

In this embodiment, as shown in FIG. 3, a straight line L in the longitudinal direction of the vehicle body connects the crankshaft 23 and the input shaft 24.
The intermediate shaft 25 and the output shaft 26 are arranged above the straight line L, and the engine mounting part A is provided below the straight line L.

On the other hand, there is a bolt 58 on the left side of the engine E.
A left engine cover 60 is attached via..., and a chamber S1 is formed inside this cover 60. Further, a right engine cover 62 is attached to the right side surface of the engine E via bolts 61, and a chamber S2 is formed within this cover 62. The right engine cover 62 is formed with a large number of openings 62a corresponding to the fans 35 (see FIG. 5), and the upper part of the right engine cover 62 is provided with an IG coil 64, as shown in FIGS. Install CDI unit 65. Further, a bulging portion 67 that bulges forward is formed at the front portion of the right engine cover 62, and the bulging portion 67 surrounds the oil pump P.

On the other hand, the left case 21 of the crankcase 20
As shown in FIGS. 2 and 5, a cooling air intake port 70 and a cooling air intake port 71 are formed in the crankcase 20 as shown in FIG.
The left case 21 has a rib 21 located below the outlet 71.
form a. Therefore, together with the crankshaft 23, the fan 3
5 rotates, and the cooling air taken into the right engine cover 62 from the opening 62a of the right engine cover 62 flows into the chamber S1 from the intake port 70 as shown by the arrow, and then flows through the fan 48.
c and flows through the chamber S1 to cool each member within the chamber S1. This cooling air flows from the outlet 71 to the left case 21.
It flows out of the left case 21, flows down to the left case 21, and further goes to the rib 21.
It flows out to the rear by a.

In the above, in this embodiment, the crankshaft 23
Since the intermediate shaft 25 and the output shaft 26 are arranged above a straight line L in the longitudinal direction of the vehicle body connecting the input shaft 24 and the input shaft 24, and the engine mounting part A is provided below the straight line L (this mounting part A is specifically protrudes below the left case 21), making it possible to shorten the longitudinal length of Engine E while ensuring minimum ground clearance.

FIG. 8 shows a longitudinal section of a flywheel mounting portion according to another embodiment. In this embodiment, a recess 31a facing inward is formed in the mounting portion 31, and the inner end of the flywheel 32 is inserted into this recess 31a. They are fitted and fixed with a cylindrical member 80 and a nut 81.

[0027]

[Effects of the Invention] As described above, according to the present invention, since the intermediate shaft and the output shaft are arranged above the straight line in the longitudinal direction of the vehicle body connecting the crankshaft and the input shaft, the engine does not bulge downward. . Therefore, even with a structure in which the engine mounting portion is provided below the straight line, a sufficient minimum ground clearance can be ensured, and the longitudinal length of the engine can be shortened.

[Brief explanation of the drawing]

[Figure 1] Side view of a motorcycle

[Figure 2] Left side view of the engine

[Figure 3] Longitudinal cross-sectional view of the engine

[Figure 4] Right side view of the engine

[Figure 5] Internal exploded view of the engine

[Figure 6] View from arrow 6 in Figure 4

[Figure 7] View from arrow 7 in Figure 4

[Fig. 8] Vertical cross-sectional view of a flywheel mounting part according to another embodiment

[Explanation of symbols]

23...Crankshaft, 24...Input shaft, 25...Intermediate shaft, 26
...output shaft, A, B...engine mounting part, L...straight line connecting the crankshaft and input shaft.

Claims (1)

[Claims] 1. In a power transmission device for a motorcycle that decelerates the rotation of an engine crankshaft via an input shaft and an intermediate shaft and transmits the rotation to an output shaft, a straight line in the longitudinal direction of the vehicle body connecting the crankshaft and the input shaft. A power transmission device for a motorcycle, characterized in that the intermediate shaft and the output shaft are arranged above the straight line, and an engine mounting part is provided below the straight line.