JP2001323994A - Power transmitting device for compact vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reasonably achieve miniaturization of a power unit for a compact vehicle and oil lubrication. SOLUTION: In the power unit 40 wherein a differential mechanism 45 is connected to an engine 41 through a belt type continuously variable transmission 43, the engine 41 and the belt type continuously variable transmission 43 are arranged in series and the differential mechanism 45 is disposed vertically lower than the engine 41 and the transmission 43 in order to miniaturize the power unit 40 by a reasonable disposition and to reduce swing space and swing inertia even when the power unit 40 is supported in the vehicle freely to be swung. When a mechanical transmission 44 is used at the same time, a shift drum 70 thereof is placed in a corner part formed by the belt type continuously variable transmission 43 and the differential mechanism 45. A dry environment of the belt type continuously variable transmission 43 and a wet environment of the differential mechanism 45 are separated by difference of elevation to prevent lubricating oil from intruding into the dry environment.

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 that transmits power from an engine to left and right driving wheels via a belt-type continuously variable transmission and a mechanical transmission. Alternatively, the present invention relates to a lubricating structure of a power transmission device suitable for use in a small vehicle having a simple structure in which about two people ride.

[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 Application Laid-Open No. Sho 59-227523 and Japanese Patent Application Laid-Open No. 62-246648
Gazette, Japanese Patent Application Laid-Open No. 63-145854,
As described in Japanese Patent No. 56196, for example, the power of an engine is transmitted to driving wheels by a belt-type continuously variable transmission so that the vehicle can be easily driven and compared with an automatic transmission using a hydraulic control system. A simple, inexpensive and lightweight power transmission device is employed. Further, in such a small vehicle, a mechanical transmission is used together with the belt-type continuously variable transmission, and the engine power is driven by the belt-type continuously variable transmission and the mechanical transmission at a wide range of gear ratios. , And the gear ratio of the belt-type continuously variable transmission is reduced to reduce the size of the pulley around which the belt is wound.

[0004]

Here, in such a small vehicle as described above, a power train from an engine to a differential mechanism via a belt-type continuously variable transmission is integrally constructed as a power unit, and compared with the power unit. It is conceivable to reduce the size of the vehicle by enabling these devices to be mounted on a small space. Furthermore, it is conceivable that such a power unit is provided so as to be swingable with respect to the vehicle body, and is used together with a suspension mechanism for driving wheels. However, miniaturization cannot be achieved with a reasonable structure simply by unitizing these devices, and when this power unit is provided as a suspension mechanism so as to be swingable with respect to the body, the size of the body is reduced. There are various problems, such as how to reduce the space required for the swing in order to reduce the swing, and how to reduce the swing inertia in order to improve the suspension performance.

Further, since a belt-type continuously variable transmission transmits power by frictional force between a belt and a pulley, it is generally preferable to operate in a dry environment without lubricating oil, while a differential mechanism is used. Since a relatively large power is transmitted by a gear, it is generally preferable to operate in a sufficiently oil-lubricated wet environment.
Therefore, in view of such demands, simply integrating the belt-type continuously variable transmission and the differential mechanism into a single unit facilitates the penetration of lubricating oil from the wet environment into the dry environment, and the belt-type continuously variable transmission. There is a problem that the operation of the machine is disturbed.

Further, when a belt-type continuously variable transmission and a mechanical transmission are used together, there is the same problem as described above regarding how to arrange the mechanical transmission and unitize it. There is also a problem in how to arrange a mechanical transmission, which is desirably sufficiently lubricated with oil for the same reason as the differential mechanism, to reduce the size of the unit and to sufficiently lubricate the unit.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional circumstances, and rationally reduces the size of a power unit integrally incorporating a power train from an engine to a differential mechanism via a belt-type continuously variable transmission. It is another object of the present invention to provide a power transmission device for a small vehicle in which necessary dry environment and wet environment are rationally isolated. It is another object of the present invention to provide a power transmission device for a small vehicle that can achieve a reduction in size and a reasonable oil lubrication even in a power unit that also uses a mechanical transmission. Further objects of the present invention will be apparent in the following description.

[0008]

SUMMARY OF THE INVENTION The present invention relates to a power transmission system for a small vehicle in which a differential mechanism for driving and rotating left and right driving wheels by a pair of output shafts is connected to an engine via a belt-type continuously variable transmission. Yes, the engine and the belt-type continuously variable transmission are arranged in series, and the differential mechanism is arranged vertically below them, and the engine, the belt-type continuously variable transmission and the differential mechanism are assembled in an integrated case to form a power unit. It is composed. Therefore, the engine, the belt-type continuously variable transmission, and the differential mechanism are arranged in a substantially L-shape, and the engine and the belt-type continuously variable transmission are positioned higher than the output shaft to the drive wheels that define the clearing height of the vehicle that can cross an obstacle during traveling. And a rational and compact power unit in which the engine and the belt-type continuously variable transmission are arranged. Furthermore, when the power unit is provided on the vehicle body so as to be swingable, the engine does not travel upward from the belt-type continuously variable transmission. Also, since the differential mechanism is not further extended on the extension of the belt type continuously variable transmission, the power unit is housed within a relatively close range from the center of swing, and the swing space secured in the vehicle body is reduced. And the swing inertia can be reduced.

Further, in the power transmission device for a small vehicle according to the present invention, a case for accommodating a differential mechanism together with lubricating oil in a wet environment and a case for accommodating a belt type continuously variable transmission in a dry environment are integrally assembled. Since the unit is unitized and the wet environment is located vertically below, infiltration of the lubricating oil into the dry environment is effectively prevented.

Further, in the power transmission device for a small vehicle according to the present invention, a belt-type continuously variable transmission and a mechanical transmission are used in combination, and the belt-type continuously variable transmission and the differential mechanism are connected via the mechanical transmission. The mechanical transmission is housed in a wet environment case together with the differential mechanism in a wet environment case, and the mechanical transmission is mounted on a corner formed by the differential mechanism and the belt-type continuously variable transmission in the wet environment case in accordance with a driver's operation. A shift drum for switching gears of the transmission is arranged. Therefore, the mechanical transmission is sufficiently lubricated in a wet environment, and the shift drum associated with the mechanical transmission is formed by a substantially L-shaped corner portion formed by a differential mechanism and a belt-type continuously variable transmission. And a compact configuration that makes effective use of surplus space.

Further, in the power transmission device for a small vehicle according to the present invention, an oil pump for supplying the lubricating oil in the wet environment case to the bearing of the mechanical transmission is provided, and the oil pump is connected to the output of the mechanical transmission. Driven by shaft. Therefore, the amount of oil supplied by the oil pump increases as the rotational speed of the mechanical transmission increases, and the mechanical transmission can be lubricated with a sufficient amount of oil.

[0012]

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 wheel 1 changes direction 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 the side of the seat 3. As will be described later, the select lever 8 allows the mechanical two-speed automatic transmission to be selected between advanced and reverse. I have.

As shown in FIG. 3 to FIG.
A frame-type swing frame 10 is pivotally mounted on the rear end of the swing frame 10 with its tip as a pivot. An engine, a belt-type continuously variable transmission equipped with a centrifugal start clutch, a centrifugal A power unit 40 is provided which integrates a transmission clutch type two-speed automatic transmission, a differential mechanism, and the like. And
The rear wheels 2 are attached to the front ends of a pair of drive shafts 80 protruding from the differential mechanism of the power unit 40, respectively.
The left and right rear wheels 2 are driven by power from the vehicle.

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. The main frame 11 has a center pipe 14 extending in the vehicle length direction at the center of a main pipe 13 extending in the vehicle width direction.
And the main pipe 13 and the center pipe 1
4, a sub-pipe 15 for supporting the power unit 40 is bridged and welded.

The main pipe 13 is attached at both ends to an axle block 18 which rotatably supports a drive shaft 80 via brackets 17, whereby the rear wheel 2 attached to the drive shaft 80 is attached.
I support. The center pipe 14 has a front end provided with a support hole 4b formed in a rear end panel 4a of the body frame 4.
This allows the main pipe 13 to swing while restricting the parallel sliding movement while allowing the main pipe 13 to swing. Note that a rubber ring bush 4c is provided in the support hole 4b to reduce wear and noise caused by twisting between the center pipe 14 and the support hole 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 a slight rotation about the axis of the center pipe 14, the left and right rear wheels 2 operate independently so that a difference in height can occur.

As shown in detail 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. A rubber plug 32 is attached to the bracket 31, and a rear end portion (differential portion) of the power unit 40 is attached to the rubber plug 32, and the power unit 40 is mounted on the swing frame 10.
Are elastically supported at three points.

Therefore, the power unit 40 swings together with the swing frame 10 to suspend the rear wheel 2, and since the power unit 40 is rubber-mounted on the swing frame 10, engine vibrations are transmitted through the swing frame 10 to the vehicle body. To be transmitted to
Further, the swing frame 10 itself is also a rubber ring bush 4.
Since it is supported by the vehicle body via the rubber bush 22 and the rubber bush 22, transmission of engine vibration to the vehicle body is further prevented.

As shown in detail in FIGS. 8 to 10, a power unit 40 includes an engine 41, an AC generator 42,
Belt type continuously variable transmission 43, mechanical type 2 with reverse gear
A speed automatic transmission 44 and a differential mechanism 45 are integrally assembled. The power output from the engine 41 is shifted by a belt type continuously variable transmission 43 and a mechanical two-speed automatic transmission 44, and the power is The power is transmitted from the differential mechanism 45 to the drive shafts 80 connected to the left and right rear wheels 2, respectively.

That is, the power unit 40 has an engine 41 and a belt-type continuously variable transmission 43 arranged substantially in series, and a differential mechanism 45 arranged vertically below them to form an integrated unit. An engine 41 and a belt-type continuously variable transmission 43 are arranged at a position higher than a drive shaft 80 that defines a clearance opening height at a lower portion of the vehicle body, and a differential mechanism is provided at a rear portion on an extension of the engine 41 and the belt-type continuously variable transmission 43. 45 has a substantially L-shaped compact configuration that does not require a business trip. Since the power unit 40 is configured to be compact with a reasonable configuration as described above, a small vehicle on which the power unit 40 is mounted can be made more compact.
Further, when the power unit 40 is swingably provided on the vehicle body as in the present embodiment, the engine 41 and the belt-type continuously variable transmission 43 are disposed substantially flat and the rearward of the differential mechanism 45 is provided. Since it has a short shape without a business trip, the swing space that must be secured in the vehicle body to allow the power unit 40 to swing can be reduced, and the vehicle can be further downsized.

The engine 41 is a small-displacement engine (in this example, a single cylinder of about 500 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. 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 which is 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 belt-type continuously variable transmission 43 and the associated centrifugal starting clutch 57 are housed in a case space in a dry environment without lubricating oil, while the mechanical automatic transmission 44 and the differential mechanism 45 described in detail below are The oil is lubricated by being stored in the case space together with the lubricating oil. In this case structure, a space containing the belt-type continuously variable transmission 43 and a space containing the mechanical automatic transmission 44 and the differential mechanism 45 are provided. Are separated by a partition 58b of the main case 58, the belt-type continuously variable transmission 43 and the associated centrifugal starting clutch 57 are guaranteed to operate in a dry environment without lubricating oil, and the mechanical automatic transmission 44 and the differential mechanism 45 are guaranteed to operate in a wet environment with lubricating oil.

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. Therefore, the centrifugal shift clutch 64 and the centrifugal start clutch 57
Are coaxially arranged on the first transfer shaft 51, and the arrangement of these devices is compact.

According to the centrifugal transmission clutch 64, when the engine speed is relatively small and the rotation speed of the first transfer shaft 51 is small, the centrifugal shoe 63 moves to the drum 62.
And the rotational power of the first transfer shaft 51 is not transmitted to the third sub-transfer shaft 51d, but is rotated by the second sub-transfer shaft 51c to transmit the engine power. On the other hand, when the engine rotation speed further increases and the rotation speed of the first transfer shaft 51 (that is, the second sub-transfer shaft 51c) increases, the centrifugal shoe 6
3 moves radially outward due to centrifugal force and presses against the inner peripheral surface of the drum 62, connects the third sub-transfer shaft 51d to the second sub-transfer shaft 51c, rotates the engine, and rotates the engine by the third sub-transfer shaft 51d. Transmit power.

A gear portion 51e is formed on the third sub-transfer shaft 51d, and a high-speed gear 65a for shifting is always meshed. 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 allows 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 becomes the third
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 67a, and at the time of normal forward movement indicated by a solid line in FIG.
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 are opposed to 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.

Therefore, 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. Here, as shown in FIG. 10, the shift drum 70 has a substantially L-shaped structure formed by the differential mechanism 45 and the belt type continuously variable transmission 43 in the same case as the differential mechanism 45 that is lubricated with oil. The power unit 40 is disposed at a corner portion where the lubrication space can be smoothly operated by oil lubrication and the swing space of the power unit 40 is not enlarged and the power unit 40 is not lengthened. .

As described above, the gear shaft 67 is connected to one of the forward gears 65a, 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.

An oil pump 71 for supplying lubricating oil to the bearing of the mechanical automatic transmission 44 and the centrifugal clutch 64 which is lubricated with oil is attached to the case cover 60. It is connected to and driven by the second transfer shaft 66. As shown in FIG. 10 showing the power unit 40 on the swing frame 10 with the engine 41 and the cover case 60 removed,
The differential mechanism 45 is disposed at a position lower than the mechanical automatic transmission 44, and the oil level H of the lubricating oil housed in the wet environment space in the case together with the mechanical automatic transmission 44 and the differential mechanism 45 is equal to that of the ring gear 4.
The lower portion of 5a is immersed.

Therefore, the lubricating oil is supplied to the differential mechanism 45 and the gear 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 to form the case cover 60. Lubricating oil is supplied to the bearings of the mechanical automatic transmission 44 and the centrifugal shift clutch 64 through an oil passage 60c, an oil passage 51f formed in the first transfer shaft, an oil passage 66b formed in the second transfer shaft, and the like. ing. Oil pump 7 for pumping lubricating oil in this way
1 is driven by the output shaft of the mechanical automatic transmission 44 (in this example, the second transfer shaft 66), so that as the rotational speed of the mechanical automatic transmission 44 increases, the lubrication amount of the bearings and the like increases. In other words, sufficient lubrication is applied to required parts as needed.

Further, even if the case of the dry environment space and the case of the wet environment space are integrally assembled to form a unit as described above, the mechanical automatic transmission 44 and the differential mechanism 45 are not connected to the belt type continuously variable transmission 43. Since the belt-type continuously variable transmission 43 having the driven pulley 52 and the centrifugal start clutch 57 operating in a dry environment because it is disposed vertically below, the oil for lubricating the mechanical automatic transmission 44 and the differential mechanism 45 is provided. Since it is arranged at a higher position with respect to the surface H (horizontal plane), the infiltration of lubricating oil from the wet environment space into the dry environment space is surely prevented in combination with the shielding by the partition wall 58b, and the belt type Power transmission by the continuously variable transmission 43 is not hindered.

Furthermore, since the centrifugal transmission clutch 64 is configured to be connected with a certain degree of slip in the above-mentioned shifting operation so as to reduce the transmission shock, the centrifugal transmission clutch 64 is provided with a differential gear. The oil is lubricated in the same case space together with the mechanism 45 so as to have sufficient durability even when a connection operation having a certain long sliding time is performed, while the centrifugal start clutch 57 is required. The slip time is configured to be relatively short so as to satisfy the on / off characteristics of the engine power, and the engine operates in a dry environment space without lubricating oil, but the oil leaks between the dry environment space and the wet environment space. Is reliably prevented, the performance required for both clutches 57 and 64 can be satisfied.

In the upper part of the power unit 40, a plurality of recesses 72a and 72b are formed at the 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. Is in communication with That is, with such a structure, an oil breather passage having a labyrinth structure is formed in the upper part of the power unit 40, and an oil component is separated from the oil mist gas generated in the wet environment space by the oil breather passage so that the wet environment space is separated. Reflux inside and release the remaining clean gas to the outside.

According to the power transmission device for a small vehicle having the above-described configuration, in the idling operation state in which the engine 41 is started, the centrifugal start clutch 57 is in the disconnected state, 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 transmission clutch 64 is engaged, and the engine power is transmitted to the differential mechanism 45 by the high-speed gear 65a. Automatic gear shifting is performed such that the rear wheel 2 is driven and rotated. The gear shift shock caused by the gap of the reduction ratio between the low-speed gear 65b and the high-speed gear 65a is absorbed by the continuously variable transmission by the belt-type continuously variable transmission 43. That is, if the same rotation speed of the rear wheel 2 is maintained, the rotation speed of the first transfer shaft 51 changes due to this gear change.
This change is absorbed by the stepless change in the reduction ratio between the drive pulley 50 and the driven pulley 52, and the shift shock is reduced.

[0048]

As described above, according to the present invention,
In an integrated unit-type small vehicle power transmission device in which a differential mechanism is connected to an engine via a belt-type continuously variable transmission, an engine and a belt-type continuously variable transmission are arranged in series, and the differential mechanism is Because it is arranged vertically below, it can be made a reasonable and small structure in which the engine and the belt-type continuously variable transmission are arranged at a higher position than the axle. Also, when this power unit is swingably mounted on the vehicle body, The swing space can be reduced and the swing inertia can be reduced. Further, according to the present invention, since the differential mechanism in the wet environment is disposed below the belt-type continuously variable transmission in the wet environment, intrusion of lubricating oil into the dry environment is effectively prevented, and The expected operation of the continuously variable transmission is maintained. Further, according to the present invention, when a belt-type continuously variable transmission and a mechanical transmission are used together, a shift drum attached to the mechanical transmission is substantially L-shaped by a differential mechanism and a belt-type continuously variable transmission. Since it is located at the corner of the mold, it is possible to make a compact configuration that makes effective use of the excess space.Also, since the oil pump is driven by the output shaft of the mechanical transmission, the mechanical transmission can be sufficiently operated according to the number of revolutions. Lubrication can be achieved with a large amount of oil.

[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 cross-sectional plan view of a power unit of the small vehicle according to the embodiment of the present invention.

FIG. 9 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.

FIG. 10 is a view on arrow X in FIG. 8 showing the power unit of the small vehicle according to one embodiment of the present invention with the engine and a cover case removed.

[Explanation of symbols]

2: rear wheel (drive wheel), 10: swing frame, 4
0: Power unit, 41: Engine, 42: Belt-type continuously variable transmission, 44: Mechanical two-speed automatic transmission, 45:
Differential mechanism, 51: first transfer shaft, 66: second transfer shaft, 70: shift drum, 71: oil pump, 51f, 60c, 66b:
Oil passage, H: oil level,

Continued on front page F-term (reference) 3J050 AA02 AB03 BA03 BB08 CE03 CE05 CE06 DA01 3J063 AA01 AB02 AB22 AB52 AC04 BA11 BB41 CA01 CA05 CB22 CC05 CD45 XD33

Claims (4)

[Claims] 1. A differential mechanism for driving and rotating left and right driving wheels by a pair of output shafts is connected to an engine via a belt-type continuously variable transmission, and the engine and the belt-type continuously variable transmission are arranged in series. A power transmission device for a small vehicle, characterized in that a differential mechanism is arranged vertically below these, and an engine, a belt-type continuously variable transmission and a differential mechanism are assembled into an integrated case to form a unit. 2. The power transmission device for a small vehicle according to claim 1, wherein a case accommodating the differential mechanism in a wet environment together with lubricating oil and a case accommodating the belt-type continuously variable transmission in a dry environment. A power transmission device for a small vehicle, which is assembled into a unit. 3. The power transmission device for a small vehicle according to claim 2, wherein the belt-type continuously variable transmission and the differential mechanism are connected via a mechanical transmission, and the mechanical transmission is wetted together with the differential mechanism. The shift drum that switches the gears of the mechanical transmission in accordance with the driver's operation is located at the corner between the differential mechanism and the belt-type continuously variable transmission in the wet environment case. Power transmission device for small vehicles. 4. The power transmission device for a small vehicle according to claim 3, further comprising an oil pump for supplying lubricating oil in a wet environment case to a bearing of the mechanical transmission, wherein the oil pump is connected to the mechanical transmission. A power transmission device for a small vehicle, wherein the power transmission device is driven by an output shaft.