JP2001323995A - Power transmitting device for small sized vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form an oil breather in an easy structure in a case part for accommodating a mechanical transmission and a differential mechanism of a power transmitting device for a small sized vehicle with lubricating oil. SOLUTION: The cases 58 and 60 for accommodating the mechanical automatic transmission 44 and the differential mechanism 45 are divided in half. Plural spaces 72a and 72b are provided on divided surfaces of the one of the divided cases and the other of the divided cases respectively and the plural spaces 72a and 72b are connected to form the oil breather passage 72 of a labyrinth structure to connect an inside and an outside of the case. Further, a part 73b of a gasket 73 disposed between the divided cases protrudes to inside of the case to cover an inlet 72d of the oil breather passage 72. Thus, splashed lubricating oil is prevented from directly intruding into the oil breather passage 72.

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 drive wheels via a mechanical transmission or a differential mechanism.
In particular, the present invention relates to an oil breather structure of a power transmission device suitable for use in a small-sized vehicle having a simple structure on which one or two persons can 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, the power of the engine is transmitted to the drive wheels by a belt-type continuously variable transmission or a differential mechanism so that the vehicle can be easily driven. 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, unlike a belt-type continuously variable transmission that transmits power by friction between a belt and a pulley, a mechanical transmission and a differential mechanism have a relatively large power due to meshing of gears. Therefore, the oil is sufficiently lubricated. That is, lubricating oil is also accommodated in a case accommodating a mechanical transmission or a differential mechanism, and a flip-up oil supply by rotation of a gear immersed in the lubricating oil or a pressure-feed oil supply by an oil pump is performed. In the case of a wet environment in which such oil lubrication is performed, the lubricating oil is scattered and filled with the mist gasified lubricating oil due to the operation of the mechanical transmission and the differential mechanism. Will also rise.

[0005] Therefore, the power transmission device is required to have an oil breather for liquefying the splashed or gasified lubricating oil again into the case and discharging the expanded air to the outside of the case. However, in order to realize low fuel consumption and low exhaust gas in a small vehicle, the engine has a relatively small displacement and a low output, so that the power transmission device needs to have a simple structure, small size and light weight. Required,
For example, when an oil breather structure having a simple structure as conventionally known as described in Japanese Patent Publication No. 2-33541 is adopted, the function as the oil breather described above cannot be sufficiently obtained. was there.

The present invention has been made in view of the above-mentioned conventional circumstances, and halves a case for accommodating a mechanical automatic transmission or a differential mechanism together with lubricating oil. It is an object of the present invention to provide a small and lightweight power transmission device for a small vehicle, in which a favorable breather function can be obtained by simplifying the structure in which an oil breather structure is formed. Furthermore, the present invention uses a half-case oil seal gasket to further enhance the oil breather function, and also improves the workability of assembling mechanical automatic speed machines and differential mechanisms to the case. It is intended to provide a transmission device. Still another object of the present invention is to provide a power transmission device for a small vehicle having a breather structure capable of improving the rigidity of the rotation shaft supported by the half case. Further objects of the present invention will be apparent in the following description.

[0007]

SUMMARY OF THE INVENTION The present invention relates to a power transmission system for a small vehicle having a differential mechanism for transmitting the power of an engine to a pair of drive wheels. In addition to the oil lubrication of the lifting type, the case is halved in a substantially vertical plane, and a plurality of cavities are provided at a higher level than the differential mechanism of the split surface between one and the other of these halves, and these cavities are provided. An oil breather passage having a labyrinth structure is formed in communication with the oil breather passage, and one end of the oil breather passage is opened inside the case and the other end is opened outside the case. Therefore, the lubricating oil mist gasified by the operation of the differential mechanism is liquefied by the oil breather passage having the labyrinth structure and returned into the case, and the remaining normal air is discharged outside the case.

The present invention is also a power transmission device for a small vehicle for transmitting the power of an engine to a differential mechanism for driving and rotating a pair of driving wheels via a mechanical transmission. Together with the case and make it a flip-up type oil lubrication, and divide the case in half on a substantially vertical surface, and place a plurality of these cases at a higher position than the mechanical transmission at the split surface between one and the other of the half cases. A cavity is provided and an oil breather passage having a labyrinth structure is formed by connecting these spaces to each other. One end of the oil breather passage is opened inside the case and the other end is opened outside the case. Accordingly, the lubricating oil mist gasified by the operation of the mechanical transmission is liquefied by the oil breather passage having the labyrinth structure and returned into the case, and the remaining normal air is discharged outside the case.

Furthermore, in the power transmission device for a small vehicle according to the present invention, the gasket interposed between the half cases is formed so that a part thereof protrudes inward from the split surface to open the inlet opening of the oil breather passage. An oil breather passage having a labyrinth structure is formed as a through hole that covers and communicates between the cavities, and the lubricating oil scattered by jumping up is prevented from directly entering the oil breather passage, and the passage is formed. This prevents a large amount of lubricating oil from remaining inside and leaking out of the case with air. Further, in the power transmission device for a small vehicle according to the present invention, bearings are provided on one and the other of the half case, respectively, and the rotating shaft of the differential mechanism or the mechanical transmission is pivotally supported at both ends between the half cases. By separating the half case, the differential mechanism and the mechanical transmission, which are complicated mechanisms, are exposed, so that the assembling work of these mechanisms can be easily performed.

Further, in the power transmission device for a small vehicle according to the present invention, an arched passage is formed higher than the differential mechanism or the mechanical transmission in the half case, and one end of the oil breather passage is formed in the arched passage. Is communicated. Therefore, since the oil breather passage communicates with the space in the case housing the differential mechanism or the mechanical transmission via the arched passage, the splashed oil is prevented from entering the oil breather passage. You. In addition, splashing oil may drop from the opposite side (exit side) of the passage through the arched passage, and lubricating the bearings and gears disposed on the opposite side to the oil jumping position with the dripping oil. Can also.

Further, in the power transmission device for a small vehicle according to the present invention, the arch-shaped passage is formed in such a shape that the cross-sectional area of the passage gradually decreases from the inlet to the outlet of the jumped-up oil. The splashing oil in the passage is pushed by the further splashing oil, and the oil is efficiently dripped from the outlet through the passage. Further, in the power transmission device for a small vehicle according to the present invention, an arch-shaped passage is formed by forming a concave portion that is depressed inward in one of the half cases on the cover side, and the other of the concave portion and the half case is formed. Each bearing is provided, and the rotating shaft of the differential mechanism or the mechanical transmission is pivotally supported between the half cases at both ends thereof, and assembling work by separating the half cases is facilitated,
The distance between the bearings is shortened to improve the support rigidity of the rotating shaft.

[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.

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 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 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.

As the engine speed increases, the centrifugal roller 50d moves radially outward by 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 a tip of the first sub-transfer shaft 51a, a drum 55 is fixed to a 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.

The case structure of the power unit 40 will now 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 rotatably supported by a bearing 58c through a partition 58b of the main case 58, and further rotatably supported by a bearing 60b at a distal end thereof. ing.
The bearing 58c is provided with a seal 58d for preventing lubricating oil from entering the wet environment space into the dry environment space. Bearing 60b of first transfer shaft 51
A gear portion is formed in a portion near the bearing 58c, and a cylindrical second sub-transfer shaft 51c is coaxially fixed in a portion near the bearing 58c.
1c and a cylindrical third sub-transfer shaft 51d.
Are provided rotatably coaxially. That is, when the first transfer shaft 51 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 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 cover case 60 with bearings 58 e and 60 d at both ends. It is rotatably supported via. The high-speed gear 65a is connected to the second transfer shaft 6
6, the low-speed gear 65b is connected to the high-speed gear 65a via a one-way clutch bearing 65c.
It is provided coaxially above.

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.

Here, the centrifugal transmission clutch 64 is constructed so as to be connected with a certain degree of slip in such a shifting operation so as to reduce the shifting shock. Since oil lubrication is performed in the same case space together with the 45, even if such a connection operation having a somewhat long sliding time is performed, sufficient durability is provided. On the other hand, the centrifugal start clutch 57 is configured such that the slip time is relatively short, and satisfies the required on / off characteristics of the engine power, but does not include the lubricating oil separated by the partition wall 58b. Since the operation is performed in a dry environment space, the occurrence of a situation in which expected performance is impaired due to slippage caused by lubricating oil is prevented.

The second transfer shaft 66 is provided with a gear shaft 67 having a gear formed on its 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. Is provided. An engaging side 66 is fixed to the second transfer shaft 66 so as to face the claw 67a.
7 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, the reverse idler gear 6 rotatably supported on the 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 5a.
When 1 rotates, it 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.

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 cover case 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, the main case 58 and the cover case 60, which are halved in a substantially vertical plane as described above, are joined to form a case, in which the mechanical automatic transmission 44 is provided.
And a mechanical mechanism 45 for accommodating the mechanical automatic transmission 44 and the differential mechanism 45.
Is supported by the main case 58 and the cover case 60 at both ends via bearings, so that the mechanical automatic transmission 44 and the differential mechanism 45 can be exposed only by removing the cover case 60. . Therefore, the work of assembling the mechanical automatic transmission 44 and the differential mechanism 45 into the case can be easily performed, and the maintenance work of these mechanisms 44 and 45 can also be easily performed.

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. On the swing frame 10, when the engine 41 and the cover case 60 are removed, the differential mechanism 45 is positioned lower than the mechanical automatic transmission 44 as shown in FIG. The mechanical automatic transmission 44 and the differential mechanism 4
5, the oil level H of the lubricating oil contained in the wet environment space in the case is in a state where the lower portion of the ring gear 45a is immersed.

Therefore, 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. An oil passage 60c formed in the case cover 60 and an oil passage 51 formed in the first transfer shaft
f. The lubricating oil is supplied to the bearings of the mechanical automatic transmission 44 and the centrifugal clutch 64 through an oil passage 66b formed in the second transfer shaft. Since the driven pulley 52 and the centrifugal starting clutch 57 in the dry environment are disposed at a higher position than the mechanical automatic transmission 44 with respect to the oil surface H, the wet environment is combined with the shielding by the partition wall 58b. Lubricating oil is reliably prevented from entering the dry environment space from the space.

Here, above the mechanical automatic transmission 44 and the differential mechanism 45 of the power unit 40,
An oil breather passage 72 having a labyrinth structure is formed in the wet environment case accommodating the oil-lubricated mechanisms 44 and 45. That is, as shown in detail in FIG. 9, the main case 58 and the cover case 60 are liquid-tightly joined on a substantially vertical split surface with the gasket 73 interposed therebetween, and the main case 58 and the cover case 60 are joined together. A plurality of recesses 72a and 72b are formed in the portion, and a plurality of recesses are formed by the recesses 72a and 72b by joining the main case 58 and the cover case 60. The portion of the gasket 73 sandwiched between the cases 58 and 60 has a plurality of through holes 7.
3a are formed to communicate between the concave portions 72a and 72b, and the edges of the concave portions 72a and 72b are alternately cut away, so that the formed multiple-stage voids are formed by a zigzag path 72c. Communicating.

The lowermost part of the plurality of cavities communicates with the wet environment space in the case accommodating the mechanical automatic transmission 44 and the differential mechanism 45 through a through hole 72d. Communicates with the outside of the case through a through hole 72e. Accordingly, the oil breather passage 72 having a labyrinth structure is formed in the upper part of the power unit 40 by simple processing such as forming and joining the concave portions 72a and 72b on the case split surface, and the oil generated in the wet environment space is formed. The oil component is separated from the mist gas by the oil breather passage 72 and refluxed into the wet environment space, and the remaining clean air is discharged to the outside.

Further, the gasket 73 has a shape in which a part 73b travels inward of the case.
3b protrudes adjacent to the inlet hole 72d of the oil breather passage 72, and blocks the hole 72d from the mechanical automatic transmission 44 and the differential mechanism 45. Therefore, the mechanical automatic transmission 44 and the differential mechanism 4
The lubricating oil droplets scattered by the operation of Step 5 are prevented from directly jumping into the oil breather passage 72 from the through hole 72d, and the function of the oil breather passage 72 for recirculating the oil mist gas can be kept good.

Here, as shown in detail in FIG. 11 as viewed in the direction of arrow XI in FIG. 8 and in FIG. 12 showing the rear appearance of the power unit 40, the cover case 60 is recessed inward from the outside at a high position. A concave portion 90 is formed, and a bearing 60 b for pivotally supporting the first transfer shaft 51 is provided at the bottom of the concave portion 90. For this reason, as shown in detail in FIG. 9, the gap between the bearing 60 b and the bearing 58 c that pivotally supports the first transfer shaft 51 is reduced by the recess 90, and the support rigidity of the first transfer shaft 51 is reduced. Is growing. Therefore, even if the diameter of the first transfer shaft 51 is reduced, sufficient rigidity can be obtained, so that the power unit 40 can be further reduced in size and weight. Furthermore, since the rigidity of the cover case 60 itself is increased by forming the concave portion 90, rigidity sufficient to pivotally support the rotating shaft can be obtained, and the power unit 40 Can be further reduced in size and weight.

In this embodiment, by forming the concave portion 90, an arch-shaped passage 91 around the concave portion 90 is formed.
Is formed in the cover case 60, and the arch-shaped passage 91 is located higher than the mechanical automatic transmission 44 and the differential mechanism 45 accommodated in the wet environment case and communicates with the wet environment. In the direction in which the lubricating oil is splashed up by the ring gear 45a indicated by the arrow A in FIG. 11 (that is, the rotation direction of the ring gear 45a), the arch-shaped passage 91 has a tapered portion whose passage cross-sectional area gradually decreases from the inlet to the outlet. By this, the splashed-up oil that has entered the passage 91 from the inlet is pushed to the outlet side by the further splashed-up oil, and is opposed to the inlet across the bearing 60b. The lubricating oil is dropped from the outlet of the side passage. Therefore, the first parallel
By arranging the transfer shaft 51, the second transfer shaft 66, and the differential shaft 45f in an offset manner, even if the power unit is downsized in the height direction, a bearing or gear ( In this example, the lubricating oil can be dripped and supplied to the second transfer shaft 66 and the gear meshing portion thereof through the on-arch passage 91.

An inlet passage 72d of the oil breather passage 72 communicates with the arched passage 91 (in the present embodiment, near the outlet), and the oil breather passage 72 is connected to the wet environment space via the arched passage 91. Is in communication with Therefore, the inlet through-hole 72d does not directly face the wet environment space, and together with the projecting piece 73b of the gasket, it is possible to prevent the splashing oil from directly jumping into the oil breather passage 72. I have. Furthermore,
As shown in FIG. 9, the inlet through hole 72d of the oil breather is offset with a width d with respect to the ring gear 45a that jumps up the lubricating oil, whereby the oil jumps up directly into the oil breather passage 72. Is prevented.

Numeral 93 shown in FIGS. 11 and 12 is an oil suction passage connecting the lower part in the case and the oil pump 71. The oil pump 71 pumps up the lubricating oil accumulated at the bottom of the case via the passage 93. To the required site. Further, as shown in FIG. 11, an oil passage 94 may be provided for communicating the arch-shaped passage 91 with the bearing 60b of the first transfer shaft. In this case, the oil passage 94 is provided via the oil passage 60c by the oil pump 71. In conjunction with the pressure feeding, the spring-up oil is also supplied through the arched passage 91 and the oil passage 94, so that the bearing can be more effectively lubricated.

According to the power transmission apparatus for a small vehicle having the above-described structure, 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.

[0052]

As described above, according to the present invention,
The differential mechanism and the mechanical transmission are housed in a case together with lubricating oil to make a splash-up type oil lubrication, and the case is cut in half on a substantially vertical surface. Since a plurality of cavities were provided to form an oil breather passage having a labyrinth structure, and this was used as an oil breather passage communicating between the inside and outside of the case,
An oil breather structure for returning lubricating oil from mist gas generated in the case can be provided in the power transmission device for a small vehicle with a simple configuration.

Further, since the inlet of the oil breather passage is covered by a part of the gasket interposed between the half cases, it is possible to prevent the lubricating oil scattered by the splashing from directly entering the oil breather passage. In addition, bearings are provided on one and the other of the half case to pivotally support the rotating shaft of the differential mechanism and the mechanical transmission, so that the separation of the half case separates the differential mechanism and the mechanical transmission. In a bare state to facilitate the assembling work.

Further, since the oil breather passage is communicated with the case via the arched passage, it is possible to prevent the lubricating oil scattered by splashing from directly entering the oil breather passage, and to determine the jumping position. Oil can be supplied to the lubrication position on the opposite side through the arched passage, and since the arched passage is formed by forming a recess in the case cover, the rigidity of the case cover is improved by the recess and the case cover is used. The support rigidity of the rotating shaft that is pivotally supported is improved.

[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 plan view of a power unit of a small vehicle according to an embodiment of the present invention, as viewed in section.

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 showing the power unit of the small vehicle according to the embodiment of the present invention as viewed in the direction of arrow X in FIG. 8 with an engine and a case cover removed.

FIG. 11 is a diagram showing a case cover of the power unit of the small vehicle according to the embodiment of the present invention as viewed in the direction of arrow X in FIG.

FIG. 12 is a perspective view illustrating an appearance of a rear portion of a power unit of the small vehicle according to the embodiment of the present invention.

[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, 45c, 58c, 58e,
60b, 60d: bearing, 51: first transfer shaft,
58: main case, 60: cover case, 66: second transfer shaft, 72: oil breather, 72a,
72b: concave space, 72c, 72d, 72e: through hole
73: gasket, 73a: through hole, 73b: business trip department,
90: recess, 91: arched passage,

Continued on the front page F-term (reference) 3J050 AA02 AB03 BA03 BB08 CB09 CE05 CE06 DA01 3J063 AA01 AB02 AB22 AB52 AC04 AC11 BA01 BA13 CA01 CA05 CD45 CD69 XD47 XG13 XG42

Claims (7)

[Claims] 1. A power transmission device for a small vehicle having a differential mechanism for transmitting the power of an engine to a pair of drive wheels, wherein the differential mechanism is housed in a case together with lubricating oil to provide a flip-up type oil lubrication. The case is halved on a substantially vertical surface, and a plurality of cavities are provided at a higher level than the differential mechanism at the split surface between one and the other of the halved case, and these cavities are connected to form a labyrinth structure oil breather passage. A power transmission device for a small vehicle, wherein one end of an oil breather passage is formed inside the case and the other end is opened outside the case. 2. A power transmission device for a small vehicle that transmits the power of an engine to a differential mechanism that drives and rotates a pair of drive wheels via a mechanical transmission, wherein the mechanical transmission is housed in a case together with lubricating oil. Oil lubrication using a flip-up method, and halving the case in a substantially vertical plane, providing a plurality of cavities higher than the mechanical transmission at the split surface between one and the other of the half case. A power transmission device for a small vehicle, characterized in that an oil breather passage having a labyrinth structure is formed by communicating the empty space, and one end of the oil breather passage is opened inside the case and the other end is opened outside the case. 3. The power transmission device for a small vehicle according to claim 1, wherein the half case is integrally assembled via a gasket, and a part of the gasket is disposed inside the case from the split surface portion. A power transmission device for a small vehicle, wherein the power transmission device protrudes to cover one end opening of an oil breather passage, and has a through hole communicating between cavities. 4. The power transmission device for a small vehicle according to claim 1, wherein a bearing is provided on one and the other of the half case, and the differential mechanism or the mechanical transmission is provided. A power transmission device for a small vehicle, wherein a rotating shaft is pivotally supported between half cases at both ends thereof. 5. The power transmission device for a small vehicle according to claim 1, wherein an arch-shaped passage is formed higher than the differential mechanism or the mechanical transmission in the half case. A power transmission device for a small vehicle, wherein one end of an oil breather passage communicates with the arch-shaped passage. 6. The power transmission device for a small vehicle according to claim 6, wherein the arch-shaped passage is formed in a shape such that the cross-sectional area of the passage gradually decreases from the inlet to the outlet of the bounced oil. Power transmission device for small vehicles. 7. The power transmission device for a small vehicle according to claim 5, wherein an arch-shaped passage is formed by forming a concave portion that is depressed inward in one of the half cases on the cover side. A bearing is provided in each of the concave portion and the other half case,
A power transmission device for a small vehicle, wherein a rotation shaft of a differential mechanism or a mechanical transmission is pivotally supported at both ends between half cases.