JP2001322442A - Power transmission device for small-sized vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize the comfortable movement of a small-sized vehicle with low fuel consumption and low exhaust gas quantity by adapting a flexible drive shaft with a lightweight and simple structure with a vibration isolating structure for power unit. SOLUTION: A power unit 40 having an engine 41 and differential mechanism 45 integrally mounted thereon is elastically supported on a vehicle body 4 through rubber bushes 30 and 32, and a differential mechanism output shaft f is connected to a drive wheel 2 through a flexible drive shaft 81 of cylindrical structure subjected to bellows working or a flexible drive shaft 82 of double cylindrical structure connected through an elastic body 82d, whereby the power unit is loaded on the vehicle body with a vibration isolating structure, and the differential mechanism is connected to the drive wheel through the lightweight flexible drive shaft with a simple structure.

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 small vehicle in which power from an engine is transmitted to left and right driving wheels by a differential mechanism as a power unit structure in which an engine and a differential mechanism are integrally assembled. The present invention relates to a power transmission device suitable for use in a small-sized vehicle having a simple structure on which one or two people can get on.

[0002]

2. Description of the Related Art In recent years, from the viewpoint of reduction of exhaust gas and reduction of energy consumption, a small vehicle in which about one or two persons can move while riding has been developed and put to practical use. Such a small vehicle is configured in a self-supporting form such as a four-wheeled vehicle or a three-wheeled vehicle.
As described in Japanese Patent Publication No. 348, a small-displacement engine is used as a power source, and is used as a means that allows a small number of people to easily move with low fuel consumption and low exhaust gas amount.

In such a small vehicle, Japanese Patent Laid-Open No. 59-2
No. 27523, JP-A-62-246648,
As described in Japanese Patent Publication No. 6-56196,
The power of the engine is transmitted to the differential mechanism via a belt-type continuously variable transmission or a mechanical transmission so that the left and right drive wheels are driven and rotated, and the equipment from the engine to the differential mechanism is integrated. The power unit is assembled into a power unit, and the power train equipment is compactly mounted on the vehicle.

In a conventional general vehicle, an output shaft of a differential mechanism and left and right drive wheels are connected by a flexible drive shaft using a mechanical universal joint such as a universal joint for traveling. A suspension system that enables swinging of the driving wheels is adopted. Also,
Conventional small vehicles use a swing type suspension system that swings the power unit from the engine to the differential mechanism with respect to the vehicle body, thereby enabling the drive wheels to swing during traveling. Some are.

[0005]

Here, a small vehicle has a simple body structure in order to reduce the weight and cost. However, it is necessary to prevent vibration generated during operation of the engine from being transmitted to the vehicle body. Is an important issue. As a countermeasure, a vibration isolating structure that elastically supports the power unit with respect to the vehicle body is conceivable.However, the power unit can be displaced with respect to the vehicle body by the vibration isolating structure. The drive shaft connecting the wheel must be flexible.

However, in a vehicle structure of a small vehicle, the use of the above-mentioned flexible drive shaft made of a mechanical universal joint causes an increase in weight and cost, resulting in low fuel consumption and low fuel consumption by using a small displacement engine. There is a problem that it is not possible to satisfy a demand for a small vehicle that should be a means capable of moving comfortably with a low exhaust gas amount.

The present invention has been made in view of the above-mentioned conventional circumstances, and employs a flexible drive shaft having a lightweight and simple structure together with a vibration isolating structure of a power unit.
An object of the present invention is to realize comfortable movement of a small vehicle with low fuel consumption and low exhaust gas amount. Another object of the present invention is to realize a swing type suspension system for a small vehicle having such a simple structure excellent in vibration isolation. Further objects of the present invention will be apparent in the following description.

[0008]

SUMMARY OF THE INVENTION The present invention is a power transmission device of the power unit type in which an engine and a differential mechanism are integrally assembled. The power transmission device has a structure in which a power unit is elastically supported on a vehicle body and connected via an elastic body. The output shaft of the differential mechanism and the drive wheels are connected by a flexible drive shaft or a flexible drive shaft having a bellows-processed cylindrical structure. Therefore, the power unit is mounted on the vehicle body in a vibration-proof structure, and the differential mechanism and the drive wheels are connected by a simple and lightweight flexible drive shaft.

Further, according to the present invention, the power unit is elastically supported by the mounting frame, and the mounting frame is elastically supported by the vehicle body, and the power unit is mounted on the vehicle body by a double vibration-proof structure, so that a greater protection can be obtained. Realize the vibration effect. Further, in the present invention, the mounting frame is swingably supported with respect to the vehicle body, and the power unit and the drive wheels are suspended in a swing manner with respect to the vehicle body, thereby realizing a simple structure of a small vehicle.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described with reference to an embodiment shown in the drawings. As shown in FIGS. 1 to 4, the small vehicle of the present example is a four-wheeled vehicle having two wheels each for a front wheel 1 and a rear wheel 2, and one occupant (driver) is seated in the center. A single-seat operation seat 3 is provided. The basic body structure of this small vehicle is such that a frame-shaped body frame 4 made of a metal pipe material such as aluminum is covered with a resin body cover 5. A roof panel 6 made of resin is arranged to cover the upper part of the occupant's seat 3 to form a cabin.

Reference numeral 7 in the figure denotes a steering wheel. By applying a steering force from the steering wheel 7 via a steering mechanism (not shown), the front wheels 1 change directions and the traveling direction of the vehicle is arbitrarily changed. I can do it. Reference numeral 8 in FIG. 1 denotes a select lever provided on a side portion of the seat 3. As will be described later, the select lever 8 allows the mechanical two-speed automatic transmission to be selected between forward and reverse. I have.

As shown in FIG. 3 to FIG.
A frame-type swing frame 10 is pivotably mounted on the rear portion of the swing frame 10 with its tip as a pivot. The swing frame 10 has an engine, a belt-type continuously variable transmission, and a centrifugal transmission clutch-type two-speed automatic transmission. A power unit 40 in which a transmission, a differential mechanism, and the like are integrated is provided. The rear wheels 2 are attached to the ends of a pair of drive shafts 80 projecting from the differential mechanism of the power unit 40, and the left and right rear wheels 2 are driven by the power from the power unit 40. .

As shown in detail in FIGS. 5 and 6, the swing frame 10 has a structure in which a substantially T-shaped main frame 11 and a pair of trailing arms 12 are combined. 4, and functions as a mount frame for elastically supporting the power unit 40. The main frame 11 includes a main pipe 13 extending in the vehicle width direction.
A center pipe 14 extending in the vehicle length direction is welded to the center of the sub pipe 1 and a sub pipe 1 for supporting a power unit 40 between the main pipe 13 and the center pipe 14.
It is a structure in which 5 is bridged and welded.

The main pipe 13 is attached at both ends to an axle block 18 that rotatably supports a flexible drive shaft 80 via brackets 17, thereby attaching to the flexible drive shaft 80. The rear wheel 2 is supported. Center pipe 14
Is inserted and supported at a front end thereof in a support hole 4b formed in a rear end panel 4a of the body frame 4 with a slight margin, thereby allowing the main pipe 13 to swing while allowing a driving force. This restricts the rotation of the mount frame (so-called windup). Note that a rubber ring bush 4c is provided in the support hole 4b, and the center pipe 14
Abrasion and resistance due to twisting between the support holes 4b.

The trailing arm 12 is attached via a pivot pin 20 to a bracket 19 attached to the vehicle body frame 4 at its base end, and can swing vertically about the pivot pin 20. I have. The trailing arm 12 is attached at its tip to the bracket 17 via a mounting pin 21 and a rubber bush 22, and swings about the pin 21 between the trailing arm 12 and the axle block 18 (main pipe 13). And, the torsional displacement due to the bending of the rubber bush 22 is allowed.

A suspension unit 25 in which a suspension spring and a shock absorber are assembled is provided between each trailing arm 12 and the vehicle body frame 4. These suspension units 25 are connected to a bracket 26 attached to the vehicle body frame 4. Each is pivotally attached to a bracket 27 attached to the trailing arm 12. That is, the swing frame 10
Are pivot pins 20 together with the rear wheels 2 as the vehicle travels.
Swings up and down around the center, and the rubber bush 2
2 and the rotation of the center pipe 14 about the axis thereof, an operation is performed such that a height difference between the left and right rear wheels 2 can be generated.

As shown in FIG. 7, a power unit 40 is rubber-mounted on the swing frame 10 at three points. That is, a bracket 29 is attached to each of the center pipe 14 and the sub-pipe 15, a rubber plug 30 is attached to these brackets 29, a front end (engine part) of the power unit 40 is attached to these rubber plugs 30, and a bracket 31 is attached to the main pipe 13. The rubber plug 32 is attached to the bracket 31 and the rear end of the power unit 40 (differential mechanism 45) is attached to the rubber plug 32.
The power unit 40 is elastically supported on the swing frame 10 at three points.

Therefore, the swing frame 10 swings together with the power unit 40 to suspend the rear wheel 2. The power unit 40 is elastically supported by the main frame 11 via rubber plugs 30 and 32 and has a drive shaft 8 connecting the power unit 40 and the rear wheel 2.
0 is flexible, the power unit is floating supported, and the main frame 11 is elastically supported by the vehicle body 4 via the rubber ring bush 4c and the rubber bush 22. It is prevented from being transmitted.

FIG. 8 shows a detailed structure of a flexible drive shaft 80 according to an example of the present invention. The flexible drive shaft 80 is substantially in the form of a cylinder subjected to bellows processing, and the output shaft 45 of the differential mechanism 45 of the power unit 40 is formed by such a bellows cylindrical shaft 81.
f and an axle shaft 18 a rotatably supported by the axle block 18 and connected to the rear wheel 2. Reference numeral 18b in the drawing denotes a bearing that rotatably supports the axle shaft 18a on the axle block 18.

That is, mounting brackets 81a are provided at both ends of the bellows-shaped cylindrical shaft 81, and one bracket 81a is mounted to a mounting bracket 81b fitted to a differential mechanism output shaft 45f by bolts 81c. And the other bracket 81a
Is attached by a bolt 81c to a mounting bracket 81b fitted to the axle shaft 18a, and connects the rear wheel 2 and an output shaft 45f of a differential mechanism. Therefore, since the drive shaft 80 has a bellows-like cylindrical shape, the drive shaft 80 has a simple and lightweight structure, and is resistant to twisting around the axis, so that the rotational force from the differential mechanism 45 can be transmitted to the rear wheel 2. Because it can be bent, and it can be flexed and slightly expanded and contracted,
Axle block 18 of power unit 40 (rear wheel 2)
Power unit 40 which is capable of swinging with respect to
The anti-vibration is realized by floating support.

FIG. 9 shows a detailed structure of a flexible drive shaft 80 according to another example of the present invention. The flexible drive shaft 80 has a substantially double-cylinder structure, and the double-shaft shaft 82 serves as a differential mechanism output shaft 45f of the power unit 40 and the axle shaft 18a connected to the rear wheel 2. And are connected. That is, the cylindrical shaft 82 has an inner cylinder 82a fitted to the differential mechanism output shaft 45f, an inner cylinder 82b fitted to the axle shaft 18a, and an outer cylinder 83c containing these inner cylinders 82a and 82b coaxially. And a rubber bush 82b connecting the inner cylinders 82a and 82b and the outer cylinder 83c, respectively.

Therefore, since the drive shaft 80 has a double cylindrical shape connected by rubber bushes, the drive shaft 80 has a simple and lightweight structure, and the rotational force from the differential mechanism 45 is transmitted to the rear wheel 2 by the deformation resistance of the rubber bush 82a. Since the power unit 40 can be transmitted and bendable by the deformation of the rubber bush 82a, the power unit 40 can swing with respect to the axle block 18 (the rear wheel 2) to realize the vibration isolation by the floating support of the power unit 40 described above. I have. Since the transmission torque of a small vehicle is relatively small, it is easy to employ such a simple and lightweight drive shaft 80 having a bellows tube shape or a double tube shape.

Next, as shown in detail in FIGS. 10 and 11, the power unit 40 comprises an engine 41, an AC generator 42, a belt-type continuously variable transmission 43, and a mechanical two-speed automatic transmission having a reverse gear. 44, a differential mechanism 45 is integrally assembled.
Is output from a belt-type continuously variable transmission 43 and a mechanical two-speed automatic transmission 44, and this power is connected from a differential mechanism 45 to the left and right rear wheels 2 as described above. It transmits to each shaft 80.

The engine 41 is a small-displacement internal combustion engine (in this example, a single cylinder of about 50 cc). The movement of a piston 47 caused by combustion and explosion is transmitted to a crankshaft 49 by a connection rod 48, and the engine power is transmitted to the crankshaft 49. Output by rotation of. An AC generator 42 is connected to one end of the crankshaft 49, and electric power required for driving the vehicle is generated by the rotational power of the engine.

A drive pulley 50 of the belt type continuously variable transmission 43 is attached to the other end of the crankshaft 49, and a first transfer shaft 51 supported in parallel with the crankshaft 49 has a cylindrical shape. 1 sub-transfer shaft 51
a is provided rotatably coaxially, and a driven pulley 52 is attached to the first sub-transfer shaft 51a, and the drive pulley 50 and the driven pulley 5
1 is connected by looping around an annular belt 53 having a substantially V-shaped cross section. The drive pulley 50 is connected to the crankshaft 49.
And a movable plate 50b fitted to the crankshaft 49 in the axial groove so as to rotate together with the crankshaft 49, but movably provided in the axial direction.
Behind the movable plate 50b, a holding plate 50c fixed to the crankshaft 49 is provided.
A centrifugal roller 50d is provided between b and the holding plate 50c.

On the other hand, the driven pulley 52 has a fixed plate 52a fixed to the first sub-transfer shaft 51a.
And a movable plate 52b which is fitted to the first sub-transfer shaft 51 in an axial groove and rotates together with the first sub-transfer shaft 51 so as to be movable in the axial direction, and the movable plate 52b is provided on the back surface thereof. It is urged toward the fixed plate 52a by the return spring 52c. Therefore, when the engine speed (crankshaft speed) is low, the interval between the movable plate 52b and the fixed plate 52a is reduced by the return spring 52c, and the belt pulling diameter of the driven pulley 52 is increased. Fixed plate 50a and movable plate 5 by tension
The interval between the drive pulley 50 and the driven pulley 51 is increased, and the belt transmission reduction ratio from the drive pulley 50 to the driven pulley 51 is increased.

When the engine speed increases, the centrifugal roller 50d moves radially outward due to centrifugal force and presses the movable plate 50b from behind, and the distance between the movable plate 50b and the fixed plate 50a decreases. As a result, the belt pulling diameter of the drive pulley 50 increases, and the return spring 52 c
The distance between the movable plate 52b and the fixed plate 52a is widened to reduce the belt running diameter of the driven pulley 52, and the reduction ratio of the belt transmission from the drive pulley 50 to the driven pulley 51 is reduced. That is, according to the belt-type continuously variable transmission 43, the reduction ratio gradually decreases as the engine speed increases, and the speed of the first sub-transfer shaft 51a increases.

A shoe plate 54 is fixed to the tip of the first sub-transfer shaft 51a, a drum 55 is fixed to the tip of the first transfer shaft 51, and a centrifugal shoe 56 is fixed to the shoe plate 54 outside. The centrifugal start clutch 57 is formed between the first transfer shaft 51 and the first sub-transfer shaft 51a. That is, when the number of revolutions of the first sub-transfer shaft 51a is low, such as at the time of engine idling, the centrifugal shoe 56 is not pressed against the inner peripheral surface of the drum 55, and the first sub-transfer shaft 51
The rotation power of the centrifugal shoe 56 is not transmitted to the first transfer shaft 51 while the engine speed increases.
Moves radially outward due to centrifugal force and presses against the inner peripheral surface of the drum 55, connects the first transfer shaft 51 to the first sub-transfer shaft 51a, rotates the first transfer shaft 51, and automatically transmits engine power from the first transfer shaft 51. Input to the transmission 44.

Here, the case structure of the power unit 40 will be described. A belt-type continuously variable transmission 43 is mounted on a main case 58 attached to an engine block with bolts 58a.
And a space for accommodating the mechanical automatic transmission 44 and the differential mechanism 45 are formed on mutually opposite surfaces, and a space for accommodating the belt-type continuously variable transmission 43 is formed by bolts 59.
The power train mechanism from the engine 41 to the differential mechanism 45 is covered by a cover case 59 attached with a cover case 59, and the space containing the mechanical automatic transmission 44 and the differential mechanism 45 is covered with a cover case 60 attached with bolts 60a. It is housed in an integrated case.

The first transfer shaft 51 is connected to the partition 5
8b, and is rotatably supported by a bearing 58c.
It is rotatably supported by. The bearing 58c is provided with a seal 58d for preventing lubricating oil from entering the wet environment space into the dry environment space. A gear portion 51 is formed at a portion of the first transfer shaft 51 near the bearing 60b, and a cylindrical second sub-transfer shaft 51c is coaxially fixed at a portion near the bearing 58c. A cylindrical third sub-transfer shaft 51d is coaxially rotatable with the transfer shaft 51c. That is, the first transfer shaft 5
When 1 rotates, the second sub-transfer shaft 51c always rotates together, but the third sub-transfer shaft 51d is relatively rotatable without such co-rotation.

A shoe plate 61 is fixed to the second sub-transfer shaft 51c, a drum 62 is fixed to the third sub-transfer shaft 51d, and a centrifugal shoe 63 is movable to the shoe plate 61 outward. And the second sub-transfer shaft 51
A centrifugal transmission clutch 64 is formed between the third sub-transfer shaft 51d and the third sub-transfer shaft 51d. That is, when the engine speed is relatively low and the rotation speed of the first transfer shaft 51 is low, the centrifugal shoe 63 is not pressed against the inner peripheral surface of the drum 62, and the rotation power of the first transfer shaft 51 is the third power. Without being transmitted to the sub-transfer shaft 51d, the second
The sub-transfer shaft 51c rotates to transmit engine power. On the other hand, the engine speed further increases and the first transfer shaft 51 (that is, the second sub-transfer shaft 5
When the rotation speed of 1c) increases, the centrifugal shoe 63 moves radially outward due to the centrifugal force and presses against the inner peripheral surface of the drum 62 to connect the third sub-transfer shaft 51d to the second sub-transfer shaft 51c. Then, the engine power is transmitted by the third sub-transfer shaft 51d.

A gear portion 51e is formed on the third sub-transfer shaft 51d, and a high-speed gear 65a for shifting is always engaged. Also, the first transfer shaft 51
The low-speed gear 65b for speed change is always meshed with the gear portion 51, and the high-speed gear 65a is set to have a reduction ratio smaller than that of the low-speed gear 65b. A second transfer shaft 66 is provided in the wet environment space of the case in parallel with the first transfer shaft 51, and the second transfer shaft 66 is provided between the main case 58 and the case cover 60 via bearings at both ends. It is rotatably supported. The high-speed gear 65a is provided coaxially fixed to the second transfer shaft 66, and the low-speed gear 65b is provided coaxially on the high-speed gear 65a via a one-way clutch bearing 65c.

The one-way clutch bearing 65c permits only the overtaking rotation of the low-speed gear 65b by the high-speed gear 65a. When the low-speed gear 65b rotates, the high-speed gear 65a rotates, but the low-speed gear 65b does not rotate. In both cases, the high-speed gear 65a can rotate.
Therefore, when the engine speed is relatively small and the centrifugal speed change clutch 64 is not connected, the engine power causes the low-speed gear 65b meshing with the gear portion 51b of the first transfer shaft 51 to rotate, and the one-way clutch bearing 6
5c via the high-speed gear 65a rotated by the second gear 5c.
The transfer shaft 66 is rotated.

On the other hand, when the engine speed further increases and the centrifugal shift clutch 64 is connected, the engine power is reduced to the third power.
The second transfer shaft 66 is directly rotated by rotating the sub-transfer shaft 51d and rotating the high-speed gear 65a meshed with the gear 51e. In this case, the low-speed gear 65b also rotates in the same manner as described above, but the one-way clutch bearing 65c causes the high-speed gear 65a to overtake it and rotate at high speed. That is, when the centrifugal shift clutch 64 is not connected, the engine power is transmitted at the reduction ratio by the low speed gear 65b, and when the centrifugal shift clutch 64 is connected, the engine power is transmitted at the reduction ratio by the high speed gear 65a.
By rotating the transfer shaft 66, the automatic transmission is easily and compactly configured such that the centrifugal transmission clutch 64 has a simple and compact structure, and the two transmission gears 65a and 65b are coaxially arranged via a one-way clutch bearing 65c. It is realized by the configuration.

The second transfer shaft 66 is provided with a gear shaft 67 having a gear formed on the outer periphery so as to be rotatable and movable in the axial direction. A claw 67a is provided at an end of the gear shaft 67. Have been. An engaging side 66 is fixed to the second transfer shaft 66 so as to face the claw portion 67a, and at the time of normal forward movement indicated by a solid line in FIG.
a meshes with the engagement piece 66, and the gear shaft 67 rotates together with the second transfer shaft 66. Further, the second transfer shaft 66 is provided with a reverse gear 68 between the gear shaft 67 and the low-speed gear 65b, and the reverse gear 68 is rotatable on the second transfer shaft 66 via a bearing. . As shown in detail in FIG. 9, a reverse idler gear 68 rotatably supported by a case cover 60 via a bearing.
The reverse gear 68 is always connected to the gear portion 51b of the first transfer shaft via the first transfer shaft 51a.
Rotates in the opposite direction to the high-speed gear 65a and the low-speed gear 65b.

A circumferential groove 67c is formed in the gear shaft 67, and a shift fork 69 is engaged with the gear shaft 67 while allowing the rotation of the gear shaft 67. The gear shaft 67 and the reverse gear 68 face each other. The surfaces are provided with claw portions 67b and 68b, respectively. A shift drum 70 rotatably supported at both ends is provided between the main case 58 and the case cover 60. The shift drum 70 has an end protruding outside the case via a lever (not shown). It is connected to the select lever 8 on the driver's seat side.

Accordingly, when the driver operates the select lever 8 to the retreat position, the shift drum 70 is rotated, the gear shaft 67 is moved to the retreat gear 68 side by the shift fork 69, and the pawl portions 67b, 68b are engaged. At the same time, the engagement between the pawl portion 67a and the engaging piece 66 is released, and the gear shaft 67 can be rotated in the opposite direction to the second transfer shaft 66 by the reverse gear 68. That is, the rotation power in the forward direction from the second transfer shaft 66 is cut off by a simple and compact reverse mechanism in which such a gear shaft 67 is shared for forward and reverse use.
The rotation of the reverse gear 68 in the reverse direction causes the gear shaft 67 to rotate.
Can be rotated.

As described above, the gear shaft 67 is connected to one of the forward gears 65a and 65 selected by the centrifugal speed change clutch 64.
b, and is rotated backward by the reverse gear 68 by the driver operating the select lever.
A ring gear 45a of the differential mechanism 45 always meshes with the gear shaft 67. The differential mechanism 45 rotatably supports a case 45b to which a ring gear 45a is attached and fixed between a main case 58 and a case cover 60 by a bearing 45c.
b, a pair of umbrella-shaped pinions 45d and a pair of umbrella-shaped side gears 45e are rotatably provided by meshing with each other, and a pair of output shafts 45f attached to the side gear 45e are respectively connected to left and right drive shafts 80. It is connected to. Accordingly, the rotation of the gear shaft 67 transmitted through the ring gear 45a in the forward or backward direction rotates the case 45b, thereby differentially rotating both side gears 45e via the pinion 45d, and driving the drive shaft 80. The connected left and right rear wheels 2 are driven.

Here, as described above, the power unit 40
Are the crankshaft 49 of the engine and the first transfer shaft 5
1, the second transfer shaft 66 and the output shaft 45f of the differential mechanism are arranged in parallel with each other, and the crankshaft 49
, A transmission belt 53 of a belt-type continuously variable transmission, and transfer shafts 51 and 66 of a mechanical transmission, are arranged in a substantially U-shape, and are substantially flush with a differential mechanism 45 arranged substantially in the middle of the left and right rear wheels 2. The engine 41 is arranged in the vehicle. Therefore, the engine 4 having a relatively large weight
1 and the differential mechanism 45 are arranged side by side substantially on the center line of the swing frame 10, so that the swing balance of the swing frame 10 is good.

The case cover 60 is provided with an oil pump 71 for pumping lubricating oil to the bearing of the mechanical automatic transmission 44 and the centrifugal clutch 64 which is lubricated with oil. It is connected to and driven by the second transfer shaft 66. Accordingly, the lubricating oil is supplied to the differential mechanism 45 and the gear of the mechanical automatic transmission 44 by the jumping up by the ring gear 45a, and the oil pump 71 pumps up the lubricating oil from the bottom of the wet environment space, so that the case cover 60 Through the oil passage 60c formed in the first transfer shaft, the oil passage 51f formed in the first transfer shaft, the oil passage 66b formed in the second transfer shaft, etc., to the bearings of the mechanical automatic transmission 44 and the centrifugal shift clutch 64. Supplying oil.

In the upper part of the power unit 40, a plurality of recesses 72a and 72b are formed at a substantially vertical joint between the main case 58 and the cover case 60, respectively. A plurality of cavities are formed by these concave portions 72a and 72b by joining the 60. Further, the concave portions 72a, 72b
Are notched alternately, so that the cavities of the plurality of stages communicate with each other through a zigzag path 72c. Further, the lowermost part of the plurality of tiers communicates with a wet environment space containing the mechanical automatic transmission 44 and the differential mechanism 45 through a through hole 72d, and the uppermost part of the plurality of tiers is externally connected through a through hole 72e. In communication with
The oil component is separated from the oil mist gas by an oil breather passage and is returned to the wet environment space, and the remaining clean gas is discharged to the outside.

According to the power transmission device for a small vehicle having the above-described structure, the centrifugal start clutch 57 is in the disconnected state in the idling operation state when the engine 41 is started, and the engine power is not transmitted to the drive wheels 2. When the engine speed increases, the centrifugal start clutch 57 is engaged, and the engine power transmitted through the belt 53 is reduced by the low-speed gear 65b and transmitted to the differential mechanism 45, whereby the rear wheel 2 is driven. It is driven and rotated. When the engine speed further increases and the speed of the first transfer shaft 51 increases, the centrifugal shift clutch 64 is engaged, and the engine power is reduced to the high speed gear 6.
5a is transmitted to the differential mechanism 45 and the rear wheel 2
The automatic transmission is performed such that the is rotated.

[0043]

As described above, according to the present invention,
Since the differential output shaft and the drive wheels are connected by a flexible drive shaft that supports the power unit elastically and is lightweight and has a simple structure, it realizes a small vehicle with low fuel consumption, low exhaust gas amount, and excellent vibration isolation performance of a small vehicle. In addition, a swing type suspension mechanism suitable for such a small vehicle can be realized.

[Brief description of the drawings]

FIG. 1 is a perspective view of a small vehicle according to an embodiment of the present invention as viewed from the front side.

FIG. 2 is a perspective view of the small vehicle according to the embodiment of the present invention as viewed from the rear side.

FIG. 3 is a plan view perspective view of the small vehicle according to the embodiment of the present invention.

FIG. 4 is a side perspective view of the small vehicle according to one embodiment of the present invention.

FIG. 5 is a plan view showing a swing frame structure of the small vehicle according to the embodiment of the present invention.

FIG. 6 is a side view showing a swing frame structure of the small vehicle according to the embodiment of the present invention.

FIG. 7 is a side view showing a mount portion of the power unit of the small vehicle according to the embodiment of the present invention.

FIG. 8 is a sectional view showing an example of a flexible drive shaft according to the present invention.

FIG. 9 is a sectional view showing another example of the flexible drive shaft according to the present invention.

FIG. 10 is a plan view of a power unit of a small vehicle according to an embodiment of the present invention as viewed in cross section.

FIG. 11 is a plan view showing a part of the power unit of the small vehicle according to the embodiment of the present invention with a different cross section.

[Explanation of symbols]

2: rear wheel (drive wheel), 10: swing frame (mount frame), 41: engine, 45: differential mechanism, 45f: differential mechanism output shaft, 80: drive shaft, 81: bellows cylindrical shaft,
82: Double cylindrical shaft,

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Takafumi Tanaka 1-4-1 Chuo, Wako-shi, Saitama F-term in Honda R & D Co., Ltd. (Reference) 3D042 AA06 AA08 AB01 CB03 CB13 CB15 CB20 DA05 DA11 3J033 AA01 BA02 BA04 BA05 BA07 BA13 BA20 BC10

Claims (4)

[Claims] In a power transmission device of a power unit type in which an engine and a differential mechanism are integrally assembled, an output of the differential mechanism is provided by a flexible drive shaft having a structure in which a power unit is elastically supported on a vehicle body and connected via an elastic body. A power transmission device for a small vehicle, wherein a shaft and drive wheels are connected. 2. A power transmission device of a power unit type in which an engine and a differential mechanism are integrally assembled, wherein an output shaft of the differential mechanism is provided by a flexible drive shaft having a cylindrical structure in which a power unit is elastically supported on a vehicle body and subjected to bellows processing. A power transmission device for a small vehicle, wherein the power transmission device is connected to a drive wheel. 3. The small vehicle power transmission device according to claim 1, wherein the power unit is elastically supported by the mounting frame, and the mounting frame is elastically supported by the vehicle body. Power transmission device. 4. The power transmission device for a small vehicle according to claim 2, wherein the mounting frame is swingably supported with respect to the vehicle body, and the power unit and the drive wheels are swingably mounted on the vehicle body. A power transmission device for a small vehicle, which is suspended.