JPH07232685A - Power unit for scooter type vehicle - Google Patents

Abstract

PURPOSE:To perform effective sound proofing by a sound proofing cover sized to a minimum limit by a method wherein the sound proofing cover with which the periphery of a reduction gear train is covered is covered from the outside of a unit case. CONSTITUTION:The rear part of a unit case 20 is covered with a sound-proofing cover 51, with which the periphery of a reduction gear train 25 is covered, from the outside. The sound-proofing cover 51 is formed in such a manner that a sound absorbing material 53 is arranged inside an outer cover 52 formed approximately in a C-shape along the curved shape of the rear of the unit case 20. The sound-proofing cover is securely fastened against the unit case 20 by utilizing a bolt 54 by which the case cover 23 of the unit case 20 is fixed to a case body 22. The outer cover 52 of the sound proofing cover 51 is formed of resin and a metallic sheet, the inner part 51A, in the direction of the width of a car, of the sound proofing 51 is extended around a space between the expansion pat 40 of a reduction gear box 39 and a rear wheel 9. Gearing noise of a reduction gear train 25 radiated from the reduction gear box 39 is prevented from generation by the sound proofing cover 51.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power unit for a scooter type vehicle in which an engine, a power transmission device and rear wheels are integrally formed, and more specifically, noise generated by a reduction gear train incorporated as a power transmission device. The present invention relates to a power unit for a scooter type vehicle that is soundproof.

[0002]

2. Description of the Related Art Most scooter type vehicles include a power unit in which an engine, a power transmission device and rear wheels are integrally formed. In such a power unit, a rear wheel is pivotally supported by a rear portion of a unit case that is connected to a crankcase of an engine and extends rearward. Generally, a V-belt automatic transmission and a reduction gear train are incorporated in the unit case as a power transmission device, and the power of the engine is further changed by the reduction gear train after being shifted by the V-belt automatic transmission. It is decelerated and drives the rear wheels.

When the scooter type vehicle is running, each of the power transmission devices incorporated in the unit case emits noise. Therefore, there is a power unit that prevents noise by covering the outside of the unit case with a soundproof cover. Power unit disclosed in Japanese Patent Publication No. 50085).

[0004]

However, conventionally, such a soundproof cover for a power unit mainly covers only the V-belt automatic transmission portion, but not the reduction gear train portion. For this reason, the meshing noise of the reduction gear train, which is the largest noise source, easily leaks to the outside, and a sufficient effect as a soundproof cover cannot be expected.

Moreover, in order to cover the V-belt automatic transmission, the area of the soundproof cover must be made very large. As a result, the soundproof cover having a low effect requires a large power unit and an increased weight. Had to be forced.

The present invention has been made to solve this problem, and an object of the present invention is to provide a power unit for a scooter type vehicle capable of effectively providing soundproofing with a soundproof cover having a minimum size. To do.

Another object of the present invention is to prevent the meshing noise of the reduction gear train, which is the largest noise source, and also the noise generated by the V-belt automatic transmission and other devices. It is to provide a power unit for a scooter type vehicle capable of performing

[0008]

In order to achieve the above object, a power unit for a scooter type vehicle according to the present invention comprises:
A unit case extending rearward is continuously provided to the crankcase of the engine, and a rear wheel is pivotally supported at the rear portion of the unit case. A deceleration for decelerating the power of the engine and transmitting it to the rear wheel inside the unit case. In a power unit of a scooter type vehicle provided with a gear train, a soundproof cover that covers the periphery of the reduction gear train is covered from the outside of the unit case.

The soundproof cover may be provided with an extension cover for covering the entire unit case.

[0010]

According to the power unit of the scooter type vehicle having the above-mentioned structure, since the periphery of the reduction gear train is covered by the soundproof cover, the meshing sound of the reduction gear train, which is the largest noise source of the power unit, is effectively prevented. , Driving noise is very low.

Since the area of the soundproof cover required to cover the reduction gear train is much smaller than that of the conventional soundproof cover which covers the entire unit case, the soundproof cover of the minimum size is extremely small. Can be effectively soundproofed.

If the soundproof cover is provided with an extension cover for covering the entire unit case, the noise generated by the V-belt automatic transmission and other devices can be prevented as well as the meshing sound of the reduction gear train. The soundproofing effect is further improved.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a left side view of a scooter type vehicle equipped with a power unit according to the present invention. This scooter type vehicle 1 is provided with an underbone type vehicle body frame 2, and a front wheel 4 is axially supported by a front fork 3 supported by a front head of the vehicle body frame 2 so as to be rotatable left and right. A handlebar 5 is provided for steering the 4 to the left and right.

On the other hand, a power unit 8 is vertically swingably connected to a pivot shaft 6 provided at the center of the lower portion of the body frame 2 via a link 7.
A rear wheel 9 is pivotally supported on the rear part of the vehicle. A shock absorber 11 is connected between the rear portion of the power unit 8 and the rear portion of the vehicle body frame 2, and the expansion and contraction of the shock absorber 11 causes the power unit 8 and the rear wheels 9 to swing up and down when the scooter type vehicle 1 is running. Motion is buffered and restored.

A monocoque body 12 capable of accommodating an article such as a helmet is formed at the rear portion of the vehicle body frame 2, and a seating seat 13 is openably and closably installed in the upper opening thereof. At the rear of the monocoque body 12, members such as a fuel tank 14 are arranged.

The body frame 2 is entirely covered with the resin frame cover 15 so that the appearance of the scooter type vehicle is adjusted and the respective devices are protected. The middle portion of the vehicle body frame 2 is indented downward, and a step board 16 is formed in this portion as a part of the frame cover 15.

The occupant of the scooter type vehicle 1 has a sitting seat 13
Sit down to hold the handlebar 5 with both hands and place both feet on the step board 16 to drive the scooter type vehicle 1.

FIG. 2 is a left side view of the power unit 8, and FIG. 3 is a transverse sectional view of the power unit 8 taken along the line III-III in FIG. 2, showing a first embodiment of the present invention.

An engine 18 is provided on the front of the power unit 8.
Is provided with the crankcase 19 of this engine 18
On one side (for example, the left side), a unit case 20 is continuously provided so as to extend rearward, and the rear wheel 9 is pivotally supported by an axle shaft 21 at the rear portion of the unit case 20.

The unit case 20 is composed of a case body 22 which is integrally provided with the crank case 19 and a case cover 23 which is detachably attached to the left side opening of the case body 22. Inside the 20 is a V-belt automatic transmission 24 that transmits the power of the engine 18 to the rear wheels 24.
And the reduction gear train 25 is built in. As shown in FIG. 2, a carburetor 26 is provided above the engine 18,
An air cleaner 27 is connected to the carburetor 26.

The engine 18 is, for example, a forced-air cooling type two-cycle single-cylinder engine, and a cylinder block 28 and a cylinder head 29 are provided on the front surface of the crankcase 19 so as to extend forward. A piston 31 is slidably inserted in a cylinder bore 30 formed in the cylinder block 28, and the piston 31 is connected to a crankshaft 33 by a connecting rod 32. Therefore, the reciprocating motion of the piston 31 in the cylinder bore 30 is performed. Are converted into rotational movement of the crankshaft 33.

The left end of the crankshaft 33 extends into the unit case 20, and the drive pulley 34 of the V-belt automatic transmission 24 is rotatably provided at the left end.
A driven pulley 35 of the V-belt automatic transmission 24 and a centrifugal clutch 37 are pivotally supported by a driven shaft 35 which is pivotally supported at the rear portion of the unit case 20, and between the drive pulley 34 and the driven pulley 36. A V-belt 38 is wound around.

A reduction gear box 39 is liquid-tightly defined in a rear portion of the unit case 20, and the reduction gear train is provided therein.
25 are accommodated. The reduction gear box 39 has a bulging portion 40 that bulges toward the rear wheel 9 at the rear portion of the case body 22,
A gear box cover 41 is defined in a liquid-tight manner from the inside of the bulging portion 40, and lubricating oil is injected into the reduction gear box 39.

The axle shaft 21 and the driven shaft 35 are rotatably supported by the reduction gear box 39 using bearings, and the idle shaft 42 is rotatably supported by bearings between the axle shaft 21 and the driven shaft 35. .

The driven shaft 35 has a first gear 43, and the idle shaft 42 has a second gear 44 and a third gear 45.
Further, the axle shaft 21 is provided with a fourth gear 46 for rotation integrally therewith, and the first gear 43 to the fourth gear 46 are sequentially meshed with each other to form a reduction gear train 25.

Drive pulley of V-belt automatic transmission 14
The effective diameter of the crankshaft 34 increases as the rotation speed of the crankshaft 33 increases, utilizing the centrifugal force. Meanwhile, driven pulley 36
On the contrary, since the effective diameter decreases, the rotation of the drive pulley 34 (crankshaft 33) is automatically changed (accelerated) and transmitted to the driven pulley 36. The rotation of the driven pulley 36 is transmitted to the driven shaft 35 via the centrifugal clutch 37, and the rotation of the driven shaft 35 is reduced to two stages by the reduction gear train 25 and then transmitted to the axle shaft 21 to drive the rear wheel 9. To be done.

An air-cooled cowling is provided around the engine 18.
An air cooling fan 49 is provided inside the air intake 48 provided on the right side of the air cooling cowling 47.
Is integrally provided on the right end of the crankshaft 33. Therefore, when the crankshaft 33 rotates,
The air cooling fan 49 integrally rotates to take in outside air from the air intake port 48 into the air cooling cowling 47, and the engine 18 is forcibly cooled by the outside air.

As shown in FIGS. 1 to 4, a soundproof cover 51 that covers the periphery of the reduction gear train 25 is externally attached to the rear portion of the unit case 20. This soundproof cover 51
For example, a sound absorbing material 53 is provided inside an outer cover 52 formed in a substantially C shape along the curved shape of the rear part of the unit case 20, and for example, the case cover of the unit case 20.
It is fastened together with the unit case 20 using a bolt 54 for fixing the 23 to the case body 22. In this embodiment,
The soundproof cover 51 is fixed to the unit case 20 using the three bolts 54 (see FIG. 2).

The outer cover 52 of the soundproof cover 51 is made of resin or a metal plate, and the sound absorbing material 53 is made of sponge, glass wool or the like. A portion 51A of the soundproof cover 51 on the inner side in the vehicle width direction extends around between the bulging portion 40 of the reduction gear box 39 and the rear wheel 9. The soundproof cover 51 prevents the meshing sound of the reduction gear train 25 radiated from the reduction gearbox 39.

When the outer cover 52 is made of resin, as shown in FIG. 4, the metal bush 55 is press-fitted into the portion where the outer cover 52 is fastened with the bolts 54, and the fastening force of the bolts 54 is increased. It is prevented from directly joining the cover 52.

By providing such a soundproof cover 51, the meshing sound of the reduction gear train 25, which is the maximum noise source of the power unit 8, is effectively soundproofed, and the noise during traveling becomes extremely small. Since the area of the soundproof cover 51 is significantly smaller than that of the conventional soundproof cover that covers the entire unit case 20, it is possible to provide very effective soundproofing with the minimum size of the soundproof cover 51. it can.

FIG. 5 is a cross-sectional view of the power unit 8 showing the second embodiment of the present invention. In this embodiment, the unit case 20 is attached to the soundproof cover 51 that covers the periphery of the reduction gear train 25.
An extension cover 57 that covers the whole is provided. Similar to the soundproof cover 51, the extension cover 57 is configured such that a sound absorbing material 59 made of sponge, glass wool, or the like is provided inside an outer cover 58 formed of a resin, a metal plate, or the like, and the bolt 54 or the like is used as a unit. It is fixed to the case 20 and the screw
It is connected to the soundproof cover 51 by 60 or the like.

As described above, if the extension cover 57 that covers the entire unit case 20 is provided together with the soundproof cover 51, the meshing sound of the reduction gear train 25 and the automatic transmission of the V-belt 24 are provided.
The noise generated by and other devices is also soundproofed, further improving the soundproofing effect.

[0034]

As described above, in the power unit of the scooter type vehicle according to the present invention, the crankcase of the engine is provided with the unit case extending rearward, and the rear wheel is axially supported by the rear portion of the unit case. In a power unit of a scooter type vehicle in which a reduction gear train that reduces the power of the engine and transmits the power to the rear wheels is provided inside the unit case, a soundproof cover that covers the periphery of the reduction gear train is provided outside the unit case. It was worn from.

As described above, since the periphery of the reduction gear train is covered by the soundproof cover, the meshing noise of the reduction gear train, which is the largest noise source of the power unit, is effectively prevented, and the noise during traveling is extremely small. Become.

Since the area of the soundproof cover required to cover the reduction gear train is significantly smaller than that of the conventional soundproof cover that covers the entire unit case, the soundproof cover of the minimum size is extremely small. Can be effectively soundproofed.

Further, when the soundproof cover is provided with an extension cover for covering the entire unit case, noise generated by the V-belt automatic transmission and other devices is also suppressed together with the meshing sound of the reduction gear train. , The soundproofing effect is further improved.

[Brief description of drawings]

FIG. 1 is a left side view of a scooter type vehicle equipped with a power unit according to the present invention.

FIG. 2 is a left side view of the power unit.

FIG. 3 is a cross-sectional view of the power unit taken along the line III-III of FIG. 2, showing a first embodiment of the present invention.

FIG. 4 is an enlarged view of an IV portion in FIG.

FIG. 5 is a transverse sectional view of a power unit showing a second embodiment of the present invention.

[Explanation of symbols]

 1 Scooter type vehicle 8 Power unit 9 Rear wheel 18 Engine 19 Crankcase 20 Unit case 24 V-belt automatic transmission 25 Reduction gear train 51 Soundproof cover 52,58 Outer cover 53,59 Sound absorbing material 57 Extension cover

Claims (2)

[Claims] 1. A crankcase of an engine is provided with a unit case extending rearward, and a rear wheel is rotatably supported by a rear portion of the unit case. A power unit for a scooter type vehicle, comprising: a power unit for a scooter type vehicle provided with a reduction gear train for transmitting to a wheel, wherein a soundproof cover for covering the periphery of the reduction gear train is covered from outside the unit case. 2. The power unit for a scooter type vehicle according to claim 1, wherein the soundproof cover is provided with an extension cover that covers the entire unit case.