JPS6345970B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a speed reducer used in a small two-wheeled vehicle that extracts power through a centrifugal clutch.

2. Description of the Related Art Various devices have been known in the past in which the engine output taken out via a centrifugal clutch is decelerated using only a winding transmission mechanism such as a chain or belt. When using a small engine with a small displacement, the output characteristics are generally high rotation and high output, so the reduction ratio of the wrap transmission mechanism must be increased. However, if the use of a driven body of a wrap-around transmission mechanism that is too large in diameter is not allowed due to layout constraints, the driving body on the driving side must be made extremely small in diameter.

FIG. 1 is a sectional view of a conventional device, which is used in a very small leisure motorcycle called a pocket bike (pocket bike for short). In this device, the engine body 1
The rotation of the crankshaft 2 in the engine is transmitted to the sprocket 4 via the centrifugal clutch 3, and the rotation of the sprocket 4 is transmitted to the rear wheel (not shown) via a chain (not shown). ing.
The sprocket 4 and the clutch housing 3A of the clutch 3 are both welded to a rotating cylinder 5, and the rotating cylinder 5 is rotatably held by a detachable clutch cover 6. Since the outer diameter of the rear wheel side sprocket cannot be made very large due to the relationship with the rear wheel diameter, the reduction ratio is increased by making the drive side sprocket 4 smaller in diameter.

However, since the number of teeth on the sprocket 4 is practically required to be at least 7, there is a limit to the reduction ratio that can be obtained only with such a winding transmission mechanism.
It is difficult to fully utilize the output characteristics of a high-speed, high-output type engine. Further, when the number of teeth of the sprocket 4 is reduced in this way, the durability of the sprocket 4 is reduced.

This invention was made in view of these circumstances, and allows the reduction ratio to be easily increased without significantly changing the conventional device, and also allows the diameter of the driving body on the drive side of the winding transmission mechanism to be increased. The purpose of this invention is to provide a reduction gear for a small two-wheeled vehicle that is capable of

According to the present invention, this object is achieved by providing a centrifugal clutch on the side of an engine mounted near the center of the vehicle, with the clutch panel holding the clutch of the centrifugal clutch being placed on the engine side, and the clutch housing being placed on the clutch cover side. arranged,
In a small two-wheeled vehicle, the rotational output of the engine is intermittently transmitted from the clutch panel to the clutch housing via the clutch shoe, and the rotation of the clutch housing is transmitted to the rear wheel via a wrap-around transmission mechanism. An input shaft fixed at the center so as to protrude outward from the vehicle body, a reduction mechanism integrally incorporated in the clutch cover extending rearward from the outer end of the input shaft, and The gear reducer output shaft projects toward the engine side, and the driving body of the wrap-around transmission mechanism is fixed to the projecting end of the output shaft, and the clutch cover is removably attached to the side of the engine. This is achieved by a small two-wheeled vehicle speed reducer. The present invention will be explained in detail below based on the drawings.

FIG. 2 is a side view of a pocket bike to which the present invention is applied, FIG. 3 is a cross-sectional view taken along the line ``--'', and FIG. 4 is a side view of a speed reducer. In FIG. 2, 10 is a frame, and this frame 10 includes a steering head pipe 12, a rear arm 14, and a rear stay 16. 18 is this rear arm 1
4 and a rear wheel held by the rear stay 16, 20
is the front wheel held by the front fork 22, 24
is the handle, 26 is the fuel tank, 28 is the seat,
Further, 30 is a footrest.

32 is a forced air-cooled small engine mounted approximately in the center of the frame 10;
The left and right sides of the handlebar 24 and the front of the handlebar 24 are covered by a cowling 34. A portion of the left side surface of the cowling 34 is cut out, and the footrest 30 and a cover 84 of the reduction gear 60, which will be described later, are exposed from this part. Further, 35 is an exhaust pipe.

In FIG. 3, 36 is the engine body, 38 is its crankshaft, and a clutch panel 40 is fixed to this crankshaft 38. The clutch panel 40 has a large number of blower blades 42 protruding from its surface facing the engine body 36, while two clutch panels 4 are provided on the surface opposite to the engine body 36.
4 and 44 are each attached to the pin 4 so as to be swingable in the radial direction.
6,46. Reference numeral 48 denotes a clutch housing, which is formed into a short cylindrical shape with one end open, and is fixed to an input shaft 70 of a reduction gear 60, which will be described later. When this clutch housing 48 is equipped with a reducer 60 (to be described later), the inner surface of its short cylindrical portion is connected to the arc-shaped friction surfaces 45, 45 of the clutch housings 44, 44.
to face. When the crankshaft 38 rotates at a rotational speed higher than a predetermined speed, the clutches 44, 4
4 expands outwardly overcoming the spring force of a spring (not shown), and its friction surfaces 45, 45 are pressed against the clutch housing 48, thereby transmitting rotation. That is, the clutch panel 40, the clutch shoes 44, 4
4, the pins 46, 46, and the clutch housing 48 form a known centrifugal clutch 50.

The clutch panel 40 is covered with a blower case 54 on the engine main body 36 side and the outer periphery thereof,
This blower case 54 is firmly fixed to the engine body 36, and an intermediate case 56 is attached to the opening on the side opposite to the engine body 36. Note that the blower case 54 has windows 58, 58 located radially inside by the blades 42, and windows 58, 5.
Windows 59, 59 are formed to guide the atmosphere to the engine body 8, and the blower case 54 is formed to guide cooling air to cooling fins (not shown) of the air-cooled engine body 36. Therefore, when the blades 42 rotate together with the clutch panel 40 around the crankshaft 38, outside air is sucked into the case 54 through the windows 59, 59 and 58, 58, and the engine body 36 is cooled by the case 54. The engine cooling system is formed by guiding the fins.

60 is a speed reducer. This speed reducer 60 is integrally assembled with a clutch cover 62 that is attached to the clutch 50. That is, the clutch cover 62 includes a cover portion 64 that is attached to the intermediate case 56, a cylindrical portion 66 that projects laterally from the cover portion 64, and a rear wheel 1 extending from the tip of the cylindrical portion 66.
A reduction gear mounting portion 68 extending in eight directions (see FIG. 2) is integrally formed, and the cylindrical portion 66 accommodates an input shaft 70, and the reduction gear mounting portion 68 accommodates a group of reduction gears. . The clutch housing 48 is welded to one end of the input shaft 70 as described above, and the small gear 72 is fixed to the other end. Reference numeral 74 denotes an output shaft that is supported so as to protrude from the reduction gear mounting portion 68 toward the engine main body 36 side. This output shaft 7
A sprocket 76 as a driving body of the winding transmission mechanism is fixed to the protruding end on the side of the engine body 36 of No. 4.
A large gear 78 is fixed to the other end. An idle gear 80 is interposed between the large gear 78 and the small gear 72, and the large gear 78, the small gear 72,
The idle gear 80 forms a speed reduction mechanism. Note that the support shaft 82 of the idle gear 80 is connected to a cover 84 that covers this reduction mechanism and a reduction gear mounting portion 68.
is supported by

As shown in FIG. 2, this reducer 60 is aligned so that the reduction gear mounting portion 68 extends toward the rear wheel 18, and then the cover portion 64 is attached to the intermediate case 56.
Fixed. In FIG. 4, reference numeral 86 indicates a bolt hole in the cover portion 64, and the cover portion 64 is fixed to the intermediate case 56 by a bolt (not shown) inserted into the bolt hole 86.

In FIG. 2, reference numeral 88 denotes a large diameter sprocket fixed to the hub (not shown) of the rear wheel 18, and this sprocket 88 serves as a driven body of the wrap-around transmission mechanism. A chain 90 is connected between this sprocket 88 and the sprocket 76 of the reduction gear 60.
is wrapped around it.

The engine 32 is started by a recoil type starter (not shown) attached to the right end of the crankshaft 38, and when the engine 32 is started, the clutch panel 40 rotates together with the crankshaft 38 to send cooling air to the cooling fins. When the engine rotational speed is increased by operating an accelerator grip (not shown) on the right side of the handle 24, the clutches 44, 44 are pushed open by centrifugal force, and when the rotational speed exceeds a certain level, the clutch housing 48 is moved together with the clutch panel 40. Start rotating. In other words, the centrifugal clutch 50 is engaged. The rotation of the input shaft 70 and the small gear 72, which are integrated with the clutch housing 48, is caused by the rotation of the idle gear 80 and the large gear 7.
8, and is transmitted to the sprocket 76 via the output shaft 74. The rotation of the sprocket 76 is transmitted through the chain 90 to the large diameter sprocket 88 at a reduced speed, thereby driving the rear wheel 18.

The drive side sprocket 76 is connected to the reduction gear attachment part 6
8 and the cover part 64 (the third
(see figure), the sprocket 76 will not come into contact with obstacles and be damaged. Furthermore, it is possible to effectively prevent foreign matter from being caught between the sprocket 76 and the chain 90, and the chain 90 is also less likely to come off.

On the other hand, in the conventional type, the sprocket 4 was arranged coaxially with the crankshaft 2 as shown in Figure 1, which resulted in a longer chain and a greater amount of chain elongation, making it necessary to frequently adjust the chain tension. It was hot. However, according to this invention, chain 9
0 is shorter, the amount of chain elongation is reduced, and there is no need for frequent maintenance such as chain tension adjustment.

Furthermore, as in the previous embodiment, the sprocket 76
If it is arranged on the chain running surface of a conventional pocket bike, that is, if the position of the driving body (sprocket 76) in the width direction of the vehicle body is aligned with the rear wheel side driven body (sprocket 88), the conventional device This reduction gear 60 can be conveniently applied to conventional equipment by simply replacing the clutch cover with the reduction gear 60 of the present invention and changing the length of the chain.

On the other hand, in pocket bike races, the rider may ride by placing the side edges of his/her feet on the footrest 30 and holding the bike body between the left and right sides with the soles of both feet. By forming a groove or the like so that the sole of the foot comes into contact with this cover 84, the sole of the foot can firmly hold the vehicle body.

In this embodiment, the speed reduction mechanism in the speed reducer 60 is composed of a small gear 72, an idle gear 80, and a large gear 78, but the present invention allows the speed reduction mechanism to be constructed using a chain and a sprocket.

As described above, the present invention incorporates a speed reduction mechanism that extends rearward into the clutch cover that is detachable from the centrifugal clutch on the side of the engine, and causes the speed reduction gear output shaft to protrude toward the engine from the rear end of the speed reduction mechanism.
The engine output is transmitted to the reducer output shaft via the clutch housing held on the clutch cover side and the reduction mechanism, and the rotation of this output shaft is transmitted to the rear wheels by the wrap-around transmission mechanism. Since it can be attached and detached from the side of the engine together with the clutch cover, the reduction gear can be easily attached. At this time, the work is easy because the clutch housing on the clutch cover side is simply fitted into the clutch housing on the engine side.

Furthermore, since the reduction gear can increase the reduction ratio, the diameter of the driving body itself can be increased, and when a chain, a toothed belt, etc. is used in the winding transmission mechanism, the number of teeth on the driving body can be increased. Therefore, the durability of the driving body can be improved.
Furthermore, since the reduction ratio can be increased, the output of a small, high-speed, high-output engine can be used effectively.

In addition, since the deceleration mechanism is located on the opposite side of the engine across the motive force of the wrap-around transmission mechanism, there is no need to move the wrap-around drive body, such as a chain, far away from the engine. If the driving body in the conventional device is the same, there is no need to change the position of the rear wheel side driven body in the vehicle width direction.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a conventional device, FIG. 2 is a side view showing an embodiment of the present invention, FIG. 3 is a sectional view taken along the line ``--'', and FIG. 4 is a side view of the speed reducer. 32...Engine, 48...Clutch housing,
50...Centrifugal clutch, 60...Reducer, 62...Clutch cover, 70...Input shaft, 72, 78, 80
...Gear forming a reduction mechanism, 74...Output shaft, 76
...Sprocket as a driving force.

Claims (1)

[Claims] 1 A centrifugal clutch is provided on the side of an engine mounted near the center of the vehicle body, a clutch panel holding a clutch of the centrifugal clutch is disposed on the engine side, a clutch housing is disposed on the clutch cover side, and the rotation of the engine is In a small two-wheeled vehicle, the power is intermittently transmitted from the clutch panel to the clutch housing via the clutch shoe, and the rotation of the clutch housing is transmitted to the rear wheel via a wrap-around transmission mechanism. an input shaft fixed so as to protrude toward the front; a reduction mechanism integrally incorporated in the clutch cover extending rearward from the outer end of the input shaft; A small two-wheeled vehicle, comprising: a reduction gear output shaft projecting from the rear; and a driving body of the wrap-around transmission mechanism fixed to the projecting end of the output shaft, the clutch cover being removable from a side surface of the engine. Decelerator.