JP2002031201A - Power transmission device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve riding comfort with no gear shift shock by absorbing the gear shift shock generated by a mechanical automatic transmission by a continuously variable transmission while reducing the gear ratio load applied to a belt-type continuously variable transmission while using the mechanical automatic transmission. SOLUTION: This power transmission device for a vehicle transmits power of an engine 41 to drive wheels 2 through a continuously variable transmission 43 and a mechanical automatic transmission 44. The shift timing from a low gear 65b to a high gear 65a of the mechanical automatic transmission is set by being overlapped on the shift operation C of the continuously variable transmission, switching of the gear of the mechanical automatic transmission is performed in a state where room still remains in the continuously variable gear shift operation, and a shift shock is absorbed by the continuously variable gear shift operation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle power transmission device for transmitting power from an engine to drive wheels via a continuously variable automatic transmission and a mechanical stepped automatic transmission.
The present invention relates to a power transmission device suitable for use in a small vehicle having a simple structure in which about one or two people get on.

[0002]

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

In such a small vehicle, Japanese Patent 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 drive wheels by a belt-type continuously variable automatic transmission so that the vehicle can be easily driven. Further, in such a small vehicle, a mechanical automatic transmission is also used together with the belt type continuously variable automatic transmission, and the engine power is controlled by the belt type continuously variable automatic transmission and the mechanical stepped automatic transmission. The transmission is transmitted to the drive wheels at a wide range of speed ratios, and the speed ratio that the belt-type continuously variable automatic transmission bears is suppressed to reduce the size of the pulley around which the belt is wound.

[0004]

As described above, in small vehicles and the like, a belt type continuously variable automatic transmission and a mechanical stepped automatic transmission are used in combination, but the mechanical stepped automatic transmission is used. There is an advantage that the structure is not complicated and the size is small and the production cost is low. On the other hand, there is a problem that a shift shock due to the mechanical stepped automatic transmission occurs and the ride comfort of the vehicle is impaired.

That is, in the belt-type continuously variable automatic transmission, the width of the pulley is continuously changed according to the engine speed.
Since the gear ratio is changed by continuously changing the diameter of the belt wrapped around the pulley, there is no shift shock.However, mechanical stepped automatic shifting switches multiple gears for shifting. Therefore, the gear ratio shock is generated because the gear ratio is changed stepwise. Therefore, although the belt-type continuously variable automatic transmission can realize smooth running without a shift shock, a shift shock due to the mechanical stepped automatic shift has occurred and the ride comfort of the vehicle has been impaired. .

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional circumstances, and achieves a reduction in the transmission ratio load on a belt-type or other continuously variable automatic transmission by using mechanical stepped automatic transmission together. It is an object of the present invention to provide a power transmission device for a vehicle that absorbs a shift shock due to a mechanical stepped automatic shift by a continuously variable automatic transmission and realizes a comfortable ride without a shift shock as a whole. In particular, an object of the present invention is to realize a comfortable driving comfort of a vehicle while realizing easy driving particularly required for a small vehicle without increasing the size of the continuously variable automatic transmission. A further object of the present invention is to
It is clear in the following description.

[0007]

SUMMARY OF THE INVENTION The present invention relates to a power transmission system for a vehicle for transmitting engine power to driving wheels via a continuously variable automatic transmission and a mechanical stepped automatic transmission. The shift operation timing of the mechanical stepped automatic transmission was set overlapping with the shift operation. Thereby, in the belt type continuously variable automatic transmission, the width of the pulley is changed between the low ratio and the top ratio (that is, the continuously variable automatic transmission operation).
When the gears of the mechanical stepped automatic transmission are changed while there is still enough room, the gear shift shock due to the gear change is absorbed by the stepless automatic shift operation (change in the distance between the plates of the pulleys). It is solved.

Further, the present invention provides a mechanical stepped automatic transmission including a high-speed gear and a low-speed gear provided coaxially, and a low-speed gear by a high-speed gear interposed between the high-speed gear and the low-speed gear. With a configuration that includes a one-way clutch bearing that allows only overtaking rotation and a centrifugal shift clutch that switches between high-speed gear and low-speed gear, the high-speed gear and low-speed gear are arranged in a space as small as possible to reduce the size. ing.

Further, according to the present invention, the continuously variable automatic transmission is a V-belt type continuously variable automatic transmission provided on the upstream side of the mechanical stepped automatic transmission, and further, the movable pulley has a movable plate. A torque detecting cam mechanism having a cam groove for generating a component force for moving the movable pulley in a direction to decrease the plate interval of the driven pulley with an increase in the driving torque transmitted by the belt is provided. The movable pulley is moved by positively utilizing the increase in the belt transmission force due to the force in the direction of decreasing the engine rotation that occurs when the transmission is switched to the high-speed gear side, and the plate interval of the driven pulley is narrowed to reduce the low ratio direction. By shifting to, the output change due to a sudden decrease in the engine speed is prevented, and the occurrence of a shock is prevented.

The present invention is applicable not only to a belt type continuously variable automatic transmission but also to other types of continuously variable automatic transmissions such as a frame type continuously variable automatic transmission in which a transmission ratio is changed steplessly by swinging a power transmission frame. The same operation and effect can be obtained by using the automatic gear transmission. The present invention can be applied to any type of vehicle. In addition to the two-wheel drive system in which the left and right drive wheels are driven and rotated by using a differential mechanism, for example, two front wheels and one rear wheel are used. The present invention can also be applied to a one-wheel drive type vehicle in which one drive wheel is driven and rotated without using a differential mechanism like a three-wheel vehicle.

[0011]

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

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

As shown in FIG. 3 to FIG.
At the rear, a frame type swing frame 10 is pivotally mounted at the tip thereof so as to be vertically swingable. An engine, a belt-type continuously variable automatic transmission, and a centrifugal transmission clutch type two-speed Power unit 4 with integrated automatic transmission, differential mechanism, etc.
0 is provided. And this power unit 40
The rear wheels 2 are attached to the ends of a pair of drive shafts 80 projecting from the differential mechanism 45, respectively, so that the right and left rear wheels 2 are driven by the power from the power unit 40.

As shown in detail in FIGS. 5 and 6, the swing frame 10 has a structure in which a substantially T-shaped main frame 11 and a pair of trailing arms 12 are combined. 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 that 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,
A belt-type continuously variable automatic transmission 43, a mechanical two-speed automatic transmission 44 having a reverse gear, and a differential mechanism 45 are integrally assembled. The transmission is shifted by a transmission 43 and a mechanical two-speed automatic transmission 44, and this power is transmitted from a differential mechanism 45 to a drive shaft 80 connected to the left and right rear wheels 2.

The engine 41 is a small-displacement internal combustion 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 of. An AC generator 42 is connected to one end of the crankshaft 49, and electric power required for driving the vehicle is generated by the rotational power of the engine.

A drive pulley 50 of the belt-type continuously variable automatic 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. First sub-transfer shaft 5
A driven pulley 52 is attached to the first sub-transfer shaft 51a, and the drive pulley 50 and the driven pulley 51 are wound around an annular belt 53 having a substantially V-shaped cross section. Are linked. The drive pulley 50 is connected to the crankshaft 4
9 and a fixed plate 50a fixed to the crankshaft 49.
And a movable plate 50b which is fitted in the axial groove so as to rotate together therewith, but is provided so as to be movable in the axial direction. Further, a pressing plate fixed to the crankshaft 49 is provided behind the movable plate 50b. A centrifugal roller 50 is provided between the movable plate 50b and the holding plate 50c.
d is provided.

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. The shaft groove fitting portion between the first sub-transfer shaft 51 and the movable plate 52b is a torque detecting cam mechanism for applying a belt lateral pressure to the movable plate 52b as shown in detail in FIG. The details will be described later. Therefore, when the engine rotation speed (crankshaft rotation speed) is low, the interval between the movable plate 52b and the fixed plate 52a is reduced by the return spring 52c, so that the belt pulling diameter of the driven pulley 52 is increased, and the belt 53
As a result, the distance between the fixed plate 50a and the movable plate 50b is increased, the diameter of the belt around the drive pulley 50 is reduced, and the reduction ratio of the belt transmission 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, the diameter of the driven pulley 52 around the belt is reduced, and the belt transmission reduction ratio from the drive pulley 50 to the driven pulley 51 is reduced. That is, according to the belt-type continuously variable automatic 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. The space for accommodating the belt type continuously variable automatic transmission 43 in the main case 58 attached to the engine block with bolts 58a, the mechanical stepped automatic transmission 44, and the differential A space for accommodating the mechanism 45 is formed on the opposite surface, and the space for accommodating the belt-type continuously variable automatic transmission 43 is covered with a cover case 59 attached with bolts 59a.
The space containing the mechanical stepped automatic transmission 44 and the differential mechanism 45 is covered with a cover case 60 attached with bolts 60a, and the power train mechanism from the engine 41 to the differential mechanism 45 is housed in an integrated case. .

The belt-type continuously variable automatic transmission 43 and its associated centrifugal starting clutch 57 are housed in a case space in a dry environment without lubricating oil, while the mechanical continuously variable automatic transmission 44 and differential which will be described in detail below. Mechanism 4
5 is accommodated in a case space together with the lubricating oil to perform oil lubrication. In this case structure, the space containing the belt-type continuously variable automatic transmission 43, the mechanical stepped automatic transmission 44, and the differential mechanism 45 are formed. The housed space is isolated from the stored space by a partition 58b of the main case 58, and the belt-type continuously variable automatic transmission 43 and the associated centrifugal starting clutch 57 are guaranteed to operate in a dry environment without lubricating oil. The mechanical stepped automatic transmission 44 and the differential mechanism 45 are guaranteed to operate in a wet environment using 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. That is, when the engine speed is relatively low and the rotation speed of the first transfer shaft 51 is low, the centrifugal shoe 63 is not pressed against the inner peripheral surface of the drum 62, and the rotation power of the first transfer shaft 51 is the third power. Without being transmitted to the sub-transfer shaft 51d, the second
The sub-transfer shaft 51c rotates to transmit engine power. On the other hand, the engine speed further increases and the first transfer shaft 51 (that is, the second sub-transfer shaft 5
When the rotation speed of 1c) increases, the centrifugal shoe 63 moves radially outward due to the centrifugal force and presses against the inner peripheral surface of the drum 62 to connect the third sub-transfer shaft 51d to the second sub-transfer shaft 51c. The third sub-transfer shaft 51d is rotated to transmit engine 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 case cover 60 via bearings at both ends. It is rotatably supported. The high-speed gear 65a is provided coaxially fixed to the second transfer shaft 66, and the low-speed gear 65b is provided coaxially on the high-speed gear 65a via a one-way clutch bearing 65c.

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

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

The second transfer shaft 66 is provided with a gear shaft 67 having a gear formed on the outer periphery so as to be rotatable and movable in the axial direction. A claw 67a is provided at an end of the gear shaft 67. Have been. An engaging side 66 is fixed to the second transfer shaft 66 so as to face the claw 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.

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.

The case cover 60 is provided with an oil pump 71 for pumping lubricating oil to a bearing of the mechanical stepped automatic transmission 44 and a centrifugal clutch 64 which is lubricated with oil. Reference numeral 71 is connected to and driven by the second transfer shaft 66. As shown in FIG. 10, the power unit 40 on the swing frame 10 has a differential mechanism 45 disposed at a position lower than the mechanical stepped automatic transmission 44, and a case together with the mechanical stepped automatic transmission 44 and the differential mechanism 45. The oil level H of the lubricating oil stored in the wet environment space in the inside is in a state where the lower part of the ring gear 45a is immersed.

Therefore, the lubricating oil is supplied to the differential mechanism 45 and the gear of the mechanical stepped 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. Thus, an oil passage 60c formed in the case cover 60, an oil passage 51f formed in the first transfer shaft, and an oil passage 66b formed in the second transfer shaft
The lubricating oil is supplied to the bearings of the mechanical stepped automatic transmission 44 and the centrifugal shift clutch 64 through such means. In addition, since the driven pulley 52 and the centrifugal starting clutch 57 in the dry environment are arranged at a higher position than the mechanical stepped automatic transmission 44 with respect to the oil surface H, it is combined with the shielding by the partition wall portion 58b. Lubricating oil is reliably prevented from entering the wet environment space from the wet environment space.

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 portion of the plurality of cavities communicates with a wet environment space containing the mechanical stepped automatic transmission 44 and the differential mechanism 45 through a through hole 72d, and the uppermost portion of the plurality of cavities is a through hole 72e. To communicate with the outside. 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 vehicle power transmission device having the above structure,
In the idling operation state after the engine 41 is started, the centrifugal start clutch 57 is in the disengaged state and the drive wheels 2
Cannot transmit the engine power. When the engine speed increases, the centrifugal starting clutch 57 is engaged, and the engine power transmitted via 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 and rotated. Is done.

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 such that the rear wheel 2 is driven and rotated is performed, but a gear shift shock caused by a gap in the reduction ratio between the low-speed gear 65b and the high-speed gear 65a causes a belt-type continuously variable automatic transmission 43.
Is absorbed by the continuously variable automatic transmission. Engine 41
The low-speed gear 6 by the operation of the centrifugal shift clutch 64 overlaps with the continuously variable automatic shift operation of the belt-type continuously variable automatic transmission 43 performed by the displacement of the centrifugal roller 50d due to the change in the rotation speed.
5b is switched to the high-speed gear 65a, and the low-speed gear 6 is set in a state where there is still room for the stepless automatic shifting operation from the low ratio to the top ratio.
By switching from 5b to the high-speed gear 65a, the shift shock is absorbed in the margin of the continuously variable automatic shifting operation.

FIG. 11 shows the details of the shifting shock absorbing operation. If the power transmission is performed by the low-speed gear 65b without performing the gear change, as shown in FIG. 11A, when the centrifugal start clutch 57 is connected, as shown in a B1 portion in FIG. When the rotation speed (Ne) of the engine 41 increases with the speed ratio of the low-speed gear 65b, the running speed (V) of the vehicle increases, and when the engine rotation speed (Ne) becomes equal to or higher than a certain set value, The continuously variable automatic shifting operation is remarkably performed as indicated by the portion C in the figure, the running speed (V) of the vehicle increases, and the continuously variable automatic shifting operation from the low ratio to the top ratio is almost completed. When the traveling speed (V) exceeds a certain set value,
As indicated by D1 in the figure, the running speed (V) of the vehicle increases as the rotational speed (Ne) of the engine 41 increases again at the speed ratio of the low-speed gear 65b. In addition, the part A in the figure is a sliding portion at the time of starting.

On the other hand, similarly, when the power is transmitted by the high-speed gear 65a without performing the gear change, FIG.
As shown in (b), the vehicle is shifted on the running speed (V) axis, and the vehicle speed increases with the speed ratio (Ne) of the engine 41 at the speed ratio of the high-speed gear 65a as indicated by B2 in FIG. When the traveling speed (V) of the engine increases and the engine speed (Ne) exceeds a certain set value, C in FIG.
The continuously variable automatic shifting operation is remarkably performed as in the section, and the traveling speed (V) of the vehicle increases, and the continuously variable automatic shifting operation from the low ratio to the top ratio is almost completed and the traveling speed (V) Is greater than or equal to a certain set value, the traveling speed (V) of the vehicle is increased again as the rotation speed (Ne) of the engine 41 increases at the speed ratio of the high-speed gear 65a again as indicated by D2 in FIG.
Rises.

Here, in the power transmission device of the present embodiment, during the period in which the continuously variable automatic transmission operation of the belt type continuously variable automatic transmission 43 is being performed (section C), the transmission by the mechanical stepped automatic transmission 44 is performed. The operation is performed so that
When the centrifugal start clutch 57 is connected by combining the above two characteristics as shown in (c), the rotational speed (Ne) of the engine 41 is changed at the speed ratio of the low-speed gear 65b as indicated by B1 in FIG. As the running speed (V) of the vehicle increases as the vehicle speed increases, and when the engine speed (Ne) exceeds a certain set value, the continuously variable automatic shifting operation is performed as indicated by C in FIG. At the same time, the low-speed gear 65b is switched to the high-speed gear 65a during this operation, and thereafter, the rotational speed (Ne) of the engine 41 increases at the speed ratio of the high-speed gear 65a as indicated by D2 in FIG. As a result, the traveling speed (V) of the vehicle increases. Accordingly, the shift shock caused by the mechanical stepped automatic transmission 44 is absorbed by the stepless change of the pulleys 50 and 52 of the belt-type stepless automatic transmission 43, and a smooth running is realized as a whole.

More specifically, the shaft groove fitting portion between the first sub-transfer shaft 51 and the movable plate 52b includes:
As known from Japanese Utility Model Publication No. 62-33154,
A torque detecting cam mechanism as shown in FIG. 12 is configured, and together with the operation by the torque detecting cam mechanism, the shift shock of the mechanical stepped automatic transmission 44 is prevented. That is, the movable plate 5 of the driven pulley 52
A cylindrical cam sleeve 81 provided on the first sub-transfer shaft 51a is fixed to 2b. A roller pin set up on the first sub-transfer shaft 51a in a cam groove 82 formed in the cam sleeve 81. By inserting the 83, the first sub-transfer shaft 51 and the movable plate 52b are fitted in the shaft groove by the torque cam detecting mechanism including the cam sleeve 81, the cam groove 82, and the roller pin 83.

Here, the cam groove 82 is inclined at an angle θ with respect to the axial direction of the first sub-transfer shaft 51. As a result, in the state where the transmission pull is applied to the belt 53 and the driven pulley 52 is rotating, The lateral pressure acting on the belt 53 acting on the movable plate 52b is the sum of the pressing force of the spring 52c and the component force of the inclined cam groove 82, and increases the pressure contact force of the movable plate 52b against the belt 53 to increase the efficiency of belt-pulley transmission. Is increasing. Conventionally, as described above, the low-speed gear 65b is switched to the high-speed gear 65a.
When the switching to is performed, the rotation speed of the driven pulley 52 side (that is, the crankshaft 49 side) is reduced, and thereby the engine rotation speed is largely changed in a direction to decrease, thereby causing a shift shock. It will be.

However, in this embodiment, when the low-speed gear 65b is switched to the high-speed gear 65a and a force acts to reduce the rotation speed of the driven pulley 52, the transmission to the belt 53 is thereby performed. As the tension increases, a component force is generated by the inclined cam groove 82, and the movable plate 52b is moved in a direction to approach the fixed plate 52a to forcibly force the belt type automatic transmission 4
3 can be shifted to the low ratio side, and the number of revolutions of the crankshaft 49 can be kept as it is. Therefore, even if the low-speed gear 65b is switched to the high-speed gear 65a, the engine speed is prevented from being rapidly changed, and shift shock is prevented.

[0048]

As described above, according to the present invention,
In a power transmission device for a vehicle that transmits engine power to drive wheels via a continuously variable automatic transmission and a mechanical stepped automatic transmission, a mechanical stepped automatic transmission overlaps with the shifting operation of the continuously variable automatic transmission. The gear shift operation timing is set so that the mechanical stepless automatic transmission reduces the transmission ratio burden on the continuously variable automatic transmission, and the shift shock due to the mechanical stepped automatic transmission is reduced by the continuously variable automatic transmission. Absorb,
As a whole, a comfortable ride without shift shock can be realized.

[Brief description of the drawings]

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

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

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

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

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

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

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

FIG. 8 is a 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 partially sectional side view of the power unit of the small vehicle according to the embodiment of the present invention.

FIG. 11 is a diagram illustrating a shift characteristic according to an embodiment of the present invention.

FIG. 12 is a sectional view showing a torque detecting cam mechanism according to one embodiment of the present invention.

[Explanation of symbols]

2: rear wheel (drive wheel), 41: engine, 42: belt type continuously variable automatic transmission, 44: mechanical two-speed automatic transmission, 6
5a: high-speed gear, 65b: low-speed gear, B1, D1: low-speed gear running period, B2, D2: high-speed gear running period,
C: continuously variable automatic shifting period, Ne: engine speed, V:
Vehicle speed,

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Mitsuo Asumi 1-4-1 Chuo, Wako-shi, Saitama Prefecture Inside Honda R & D Co., Ltd. (72) Inventor Satoshi Yamaguchi 1-4-1 Chuo, Wako-shi, Saitama No. F-term in Honda R & D Co., Ltd. (Reference) 3D039 AA04 AA07 AB01 AB21 AC34 AC37 AC40 AC77 AD23 AD53 3J050 AA02 AB02 BA03 BB07 BB08 CA02 CD07 DA01

Claims (3)

[Claims] 1. A power transmission device for a vehicle for transmitting engine power to driving wheels via a continuously variable automatic transmission and a mechanical stepped automatic transmission, wherein the power transmission device overlaps an automatic transmission operation area of the continuously variable automatic transmission. And a shift operation timing of the mechanical stepped automatic transmission is set. 2. The power transmission device for a vehicle according to claim 1, wherein the mechanical stepped automatic transmission is provided between a high-speed gear and a low-speed gear provided coaxially and between a high-speed gear and a low-speed gear. A power transmission device for a vehicle, comprising: a one-way clutch bearing mounted to allow only a high-speed gear to overtake a low-speed gear; and a centrifugal transmission clutch for switching between a high-speed gear and a low-speed gear. 3. A continuously variable automatic transmission according to claim 1, wherein the continuously variable automatic transmission is a V-belt continuously variable automatic transmission provided upstream of the mechanical stepped automatic transmission. In addition, the movable plate of the driven pulley has a cam groove for generating a component force for moving the movable pulley in a direction to decrease the plate interval of the driven pulley in accordance with the increase of the driving rotational force transmitted by the belt. A power transmission device for a vehicle, comprising a torque detection cam mechanism described above.