CN210461613U

CN210461613U - Power transmission device for vehicle

Info

Publication number: CN210461613U
Application number: CN201920867380.7U
Authority: CN
Inventors: 大槻王一
Original assignee: Honda Motor Co Ltd
Current assignee: Honda Motor Co Ltd
Priority date: 2018-08-24
Filing date: 2019-06-11
Publication date: 2020-05-05
Anticipated expiration: 2029-06-11
Also published as: JP2020029938A

Abstract

The utility model provides a can reduce axial dimension and realize miniaturized, compact power transmission device for vehicle. The power transmission device for a vehicle includes: an engine shaft (first rotation shaft) and a counter shaft (second rotation shaft) arranged in parallel to each other, a low-speed transmission gear train and a high-speed transmission gear train for changing a speed of rotation output from an engine (drive source) to the engine shaft and transmitting the rotation to the counter shaft, and a multiple disk clutch provided corresponding to the low-speed transmission gear train and the high-speed transmission gear train, wherein the power transmission device is configured such that: the multiple disc clutches are disposed on both sides in the axial direction of a gear fixed to the engine shaft, and the clutch pistons of the multiple disc clutches and piston chambers defined by the clutch pistons are respectively incorporated into both surfaces in the axial direction of ribs of the gear.

Description

Power transmission device for vehicle

Technical Field

The utility model discloses set up a power transmission device for vehicle, by set up a plurality of change gear row and multiplate clutch in the transmission route to the drive wheel of drive power and form.

Background

In a power transmission device mounted on a hybrid vehicle (HEV vehicle) having an engine (engine) and a motor (motor) as drive sources, a clutch (clutch) is provided in a power transmission path thereof, and the power transmission path of the engine and the power transmission path of the motor are switched by the clutch, whereby the vehicle is caused to travel with only the engine or only the motor as the drive source, or with both the engine and the motor as the drive source (see, for example, patent document 1).

Further, the following method may be adopted in the power transmission device for a vehicle: namely: a plurality of transmission gear trains having different gear ratios are provided in a power transmission path of an engine, and the transmission gear trains are switched by a clutch. Specifically, a low-speed transmission gear train and a high-speed transmission gear train are provided, and these are switched by clutches provided separately. In this case, a structure in which two clutches are coaxially arranged and a structure in which two clutches are separately arranged on different axes are adopted.

[ Prior art documents ]

[ patent document ]

[ patent document 1] Japanese patent laid-open No. 2012-091708

SUMMERY OF THE UTILITY MODEL

[ problem to be solved by the utility model ]

However, in any of the structure in which the two clutches are arranged coaxially and the structure in which the two clutches are arranged separately on different shafts, the axial dimension (width dimension) of the power transmission device is increased, which may hinder the overall size reduction and compactness of the power transmission device.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a power transmission device for a vehicle, which can reduce the axial dimension and achieve miniaturization and compactness.

[ means for solving problems ]

In order to achieve the above object, the present invention provides a power transmission device for a vehicle, including: a first rotation shaft and a second rotation shaft arranged in parallel to each other; a plurality of speed change gear trains that change and transmit rotation output from a drive source to the first rotary shaft to the second rotary shaft; and a multi-plate clutch provided corresponding to each of the speed change gear rows, wherein the multi-plate clutch is disposed on each of both sides in an axial direction of a gear fixed to the first rotating shaft, and a clutch piston of each of the multi-plate clutches and a piston chamber defined by the clutch piston are respectively incorporated into both surfaces in the axial direction of a rib of the gear.

Here, the configuration may be such that: a low-speed transmission gear train and a high-speed transmission gear train are disposed on both sides of the gear in the axial direction, and the coupling of the first rotating shaft and the second rotating shaft by the low-speed transmission gear train or the high-speed transmission gear train is switched by the multi-plate clutch.

Further, the following constitution may be adopted: the clutch guide is attached to the rib of the gear by providing a cylindrical clutch guide for guiding axial movement of the clutch plates and the clutch discs, which are alternately stacked in the axial direction, inserting an engagement claw protruding from a part of each clutch guide into an engagement hole formed in the rib of the gear, and fixing the insertion end of the engagement claw by a snap ring.

Further, recesses may be formed on both surfaces of the rib of the gear in the axial direction, protrusions protruding from a clutch piston of the multiple disc clutch may be fitted into the recesses, and the piston chambers may be formed between the recesses and the protrusions, respectively, so that oil holes for supplying hydraulic pressure and holes for discharging hydraulic pressure are opened in the piston chambers, respectively.

Further, a sealing material may be fixed to a periphery of a projection provided on the clutch piston.

Further, a check valve may be provided in the hydraulic pressure discharge hole.

[ effects of the utility model ]

According to the utility model discloses, dispose the multiplate clutch respectively in the axial both sides of setting firmly the gear on the first rotation axis, and the axial both sides of the rib of gear are packed into respectively the clutch piston of each multiplate clutch with by the piston room that the clutch piston was divided, consequently the axial dimension of power transmission device for the vehicle reduces and realizes its miniaturization, compactification.

Drawings

Fig. 1 is a frame diagram schematically showing a basic structure of a vehicle power transmission device according to the present invention.

Fig. 2 is a cross-sectional view of a multi-plate clutch portion of the power transmission device of the present invention.

Fig. 3 is a perspective view of the multiple plate clutch.

Fig. 4 is a cross-sectional perspective view of the multiple plate clutch.

Fig. 5 is a sectional view showing a state in which a clutch guide of the multiple disc clutch is assembled.

Fig. 6 is a perspective view showing a state in which a clutch guide of the multiple disc clutch is assembled.

Fig. 7 is a perspective view of the clutch guide.

Fig. 8 is a cross-sectional view of an engine shaft and gears integrally formed therewith.

Fig. 9 is a perspective view of an engine shaft and a gear integrally formed therewith.

Fig. 10 is a perspective view of the clutch piston.

Description of the symbols

1: power transmission device for vehicle

3: engine shaft (first rotating shaft)

4: auxiliary shaft (second rotating shaft)

6: engine (Driving source)

7: motor with a stator having a stator core

8: generator

10: gear wheel

10A: ribs of gear

10B: concave part of rib

10 a: rib engaging hole

27: clutch guide

27 b: engaging claw of clutch guide

28: clutch disc

29: clutch disc

30: snap ring

31: clutch piston

31A: clutch piston lobe

32: sealing material

34: oilhole (oil pressure supply hole)

35: round hole (hole for oil pressure discharge)

36: check valve

C1, C2: multi-plate clutch

GH: speed change gear train for high speed

GL: low speed change gear train

S: piston chamber

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

Fig. 1 is a block diagram schematically showing a basic configuration of a power transmission device for a vehicle according to the present invention, and a power transmission device for a vehicle (hereinafter, sometimes simply referred to as "power transmission device") 1 is shown mounted on a hybrid electric vehicle (HEV vehicle), and in the power transmission device 1, a generator shaft 2, an engine shaft 3 as a first rotation axis, a counter shaft (counter draft) 4 as a second rotation axis, and right and left drive main shafts 5 are arranged in parallel with each other in the order from the top in fig. 1. The power transmission device 1 is provided with an engine 6 and a motor 7 as drive sources, and a generator (generator)8 driven by the engine 6 to generate electric power.

One end (right end in fig. 1) in the axial direction of the engine shaft 3 is connected to a crankshaft 6a of the engine 6 via a flywheel (fly wheel)9, and a gear 10 for driving the generator is integrally formed in an intermediate portion in the axial direction of the engine shaft 3. The gear 10 meshes with a small-diameter gear 11 fixed to the generator shaft 2.

Further, on both axial sides (both left and right sides in fig. 1) of the gear 10 integrally formed with the engine shaft 3, a high-speed transmission gear train GH and a low-speed transmission gear train GL are arranged, respectively. Here, the high-speed transmission gear train GH is configured by meshing a large-diameter transmission gear 12 supported on the engine shaft 3 so as to be relatively rotatable with a small-diameter transmission gear 13 fixed to the counter shaft 4. The low-speed transmission gear train GL is configured such that a large-diameter transmission gear 14 supported on the engine shaft 3 so as to be relatively rotatable meshes with a small-diameter transmission gear 15 fixed to the counter shaft 4. The outside diameter of the speed change gear 14 on the small diameter side constituting the low-speed change gear train GL is set smaller than the outside diameter of the speed change gear 12 on the large diameter side constituting the high-speed change gear train GH, and the outside diameter of the speed change gear 15 on the large diameter side constituting the low-speed change gear train GL is set larger than the outside diameter of the speed change gear 13 on the small diameter side constituting the high-speed change gear train GH. Therefore, the speed change rate (deceleration rate) of the low-speed transmission gear train GL is set to be larger than the speed change rate (deceleration rate) of the high-speed transmission gear train GH.

In the present embodiment, the multiple disc clutches C1, C2 are disposed on both axial sides (both left and right sides in fig. 1) of the gear 10 integrally formed with the engine shaft 3, corresponding to the low-speed transmission gear train GL and the high-speed transmission gear train GH, respectively. The multiple disc clutches C1 and C2 are used to switch between the low-speed transmission gear train GL and the high-speed transmission gear train GH and transmit the rotation of the engine shaft 3 to the counter shaft 4 via the low-speed transmission gear train GL or the high-speed transmission gear train GH, and a wet multiple disc clutch may be used in the present embodiment.

Further, the generator 8 is coupled to the generator shaft 2 via a clutch C, and a gear 11 fixed to the generator shaft 2 meshes with a gear 10 integrally formed with the engine shaft 3. Here, since the outer diameter of the gear 11 is set larger than the outer diameter of the gear 10, the rotation of the engine shaft 3 is increased in speed by the gears 10 and 11 engaged with each other and transmitted to the generator 8.

A small-diameter gear 17 is fixed to the counter shaft 4 between the two speed change gears 13 and 15, and a large-diameter gear 18 is fixed to the outside (left side in fig. 1) of the speed change gear 13. Here, a large-diameter ring gear 20 attached to the outer periphery of a case 19a of a differential device (differential device)19 meshes with the gear 17, and the left and right drive spindles 5 horizontally extend from the differential device 19. Drive wheels (only one of which is shown in fig. 1) W are attached to outer end portions of the left and right drive spindles 5.

The other gear 18 is engaged with a small-diameter gear 22 fixed to an end of an output shaft 21 of the motor 7 serving as a driving source. The structure of the differential device 19 is well known, and therefore, the description thereof will be omitted.

When the hybrid vehicle equipped with the power transmission device 1 configured as described above travels using only the power of the engine 6, the rotation of the crankshaft 6a of the engine 6 is transmitted to the engine shaft 3 via the flywheel 9, and the engine shaft 3 rotates integrally with the gear 10. Here, when one of the multiple disc clutches C1 is in the connected (ON) state and the other multiple disc clutch C2 is in the disconnected (OFF) state, the rotation of the engine shaft 3 is decelerated by the low-speed transmission gear train GL and transmitted to the counter shaft 4. That is, the rotation of the engine shaft 3 is transmitted to the counter shaft 4 via the transmission gears 14 and 15 engaged with each other.

Then, the counter shaft 4 rotates at a predetermined speed, and this rotation is decelerated via the gear 17 and the ring gear 20 which are engaged with each other and transmitted to the differential device 19. In the differential device 19, the case 19a rotates integrally with the ring gear 20, power (torque) is split into two by a well-known mechanism and action and transmitted to the left and right drive spindles 5, and the left and right drive spindles 5 and the drive wheels W attached thereto rotate, so that the hybrid vehicle travels only by the driving force of the engine 6.

When one of the multiple disc clutches C1 is in an OFF (OFF) state and the other multiple disc clutch C2 is in an ON (ON) state, the rotation of the engine shaft 3 is transmitted to the counter shaft 4 via the high-speed transmission gear train GH. That is, the rotation of the engine shaft 3 is transmitted to the counter shaft 4 via the transmission gears 12 and 13 engaged with each other.

Then, the counter shaft 4 rotates at a predetermined speed, and the rotation is decelerated via the gear 17 and the ring gear 20 that are engaged with each other and transmitted to the differential device 19, as described above. In the differential device 19, the case 19a rotates integrally with the ring gear 20, power (torque) is split into two by a well-known mechanism and action and transmitted to the left and right drive spindles 5, and the left and right drive spindles 5 and the drive wheels W attached thereto rotate, so that the hybrid vehicle travels by the driving force of only the engine 6.

When the hybrid vehicle travels using only the driving force of the engine 6 as described above, the rotation of the engine shaft 3 is transmitted to the generator shaft 2 via the gears 10 and 11 that are engaged with each other to rotationally drive the generator 8, whereby the generator 8 generates electric power and a battery, not shown, is charged with the electric power.

On the other hand, when the hybrid vehicle is running only by the driving force of the motor 7, the motor 7 is started in a state where both the multiple disc clutches C1, C2 are disengaged (OFF). Then, the rotation of the motor 7 is transmitted to the counter shaft 4 via the

gears

22 and 18 that mesh with each other, the rotation of the counter shaft 4 is transmitted to the differential device 19 via the gear 17 and the ring gear 20 that mesh with each other, and the case 19a of the differential device 19 rotates. Thereafter, as described above, since the power (torque) of the motor 7 is split into two by the differential device 19 and transmitted to the left and right drive shafts 5, the drive shafts 5 and the left and right drive wheels W attached thereto rotate, and the hybrid vehicle travels only by the driving force of the motor 7.

Further, when the engine 6 and the motor 7 are started simultaneously, the power (torque) of the engine 6 and the motor 7 is transmitted to the left and right drive wheels W through the transmission path described above, and therefore the hybrid vehicle can travel by the driving forces of the engine 6 and the motor 7.

Next, the structure of the multiple disc clutches C1, C2 will be described below with reference to fig. 2 to 10.

Fig. 2 is a sectional view of a multiple disc clutch portion of a power transmission device, fig. 3 is a perspective view of the multiple disc clutch, fig. 4 is a sectional perspective view of the multiple disc clutch, fig. 5 is a sectional view showing a state in which a clutch guide is assembled to the multiple disc clutch, fig. 6 is a perspective view thereof, fig. 7 is a perspective view of the clutch guide, fig. 8 is a sectional view of an engine shaft and a gear integrally formed therewith, fig. 9 is a perspective view thereof, and fig. 10 is a perspective view of a clutch piston.

As shown in fig. 2, multiple disc clutches C1, C2 are disposed on both axial sides (left and right sides) of a gear 10 integrally formed with the engine shaft 3, and transmission gears 14, 12 are rotatably disposed on the outer sides of the multiple disc clutches C1, C2, respectively. Here, both axial end portions (both right and left end portions in fig. 2) of the engine shaft 3 are rotatably supported by bearings (needle bearings) 23, 23 on a front housing (flywheel housing) 24A and a rear housing (transmission housing) 24B, respectively. As shown in fig. 2, one of the speed change gears 14 is rotatably supported by a bearing (needle bearing) 25 to the housing 24A, and the other speed change gear 12 is rotatably supported by a bearing (ball bearing) 26 to the housing 24B.

Next, the configuration of the multiple disc clutches C1, C2 will be described in detail, and since these multiple disc clutches C1, C2 are configured to be symmetrical about the gear 10 and have the same basic configuration, the configuration of one of the multiple disc clutches C1 will be mainly described below. In addition, the other multiple disc clutch C2 is illustrated and described with the same reference numerals as those of the one multiple disc clutch C1.

In the multiple disc clutch C1, a plurality of (3 in the illustrated example) annular disc-shaped

clutch discs

28 and 29 are arranged in an axially alternately stacked state between a large-diameter cylindrical clutch guide 27 as a clutch drum and a small-diameter cylindrical clutch hub 14a concentrically arranged on the inner diameter side thereof.

Here, the clutch guide 27 is formed in a cylindrical shape as shown in fig. 7, and a plurality of engaging grooves 27a are formed around the clutch guide for engaging a plurality of engaging claws 28a (see fig. 4) formed on the outer periphery of the clutch plate 28. Further, at an inner end portion (end portion on the side facing the gear 10) of the clutch guide 27, three engagement claws 27b of a circular arc curved surface shape are horizontally and integrally projected at equal angular intervals (120 ° intervals) in the circumferential direction.

On the other hand, as shown in fig. 9, circular arc slit-shaped engagement holes 10A are formed in three circumferential positions on the outer circumferential side of the rib 10A of the gear 10 (three positions corresponding to the engagement claws 27b of the clutch guide 27), and the engagement claws 27b of the clutch guide 27 are inserted into these engagement holes 10A as shown in fig. 2 and 4, and the snap ring 30 is engaged with the outer circumference of the tip (the portion protruding from the rib 10A of the gear 10), thereby fixing the clutch guide 27 to the rib 10A of the gear 10. Further, the outer peripheral portion of each clutch plate 28 is engaged with the clutch guide 27 fixed to the rib 10A of the gear 10 in this way. That is, a plurality of engagement claws 28a (see fig. 4) formed on the outer periphery of the clutch plate 28 are engaged with a plurality of engagement grooves 27a (see fig. 7) formed in the clutch guide 27, whereby the clutch plates 28 are supported by the clutch guide 27 so as to be relatively non-rotatable and movable in the axial direction.

The clutch hub 14a is integrally projected inward (leftward in fig. 2) from an inner end surface of the transmission gear 14, and a plurality of engagement grooves (not shown) are formed at equal angular intervals in the circumferential direction on the outer periphery thereof. On the other hand, as shown in fig. 4, a plurality of engaging claws 29a are formed at equal angular intervals in the circumferential direction on the inner circumferential portion of each clutch disc 29. Each clutch disc 29 is supported by the clutch hub 14a so as to be relatively non-rotatable and axially movable by engaging a plurality of engaging claws 29a formed on the inner peripheral portion thereof with a plurality of engaging grooves (not shown) formed on the outer periphery of the clutch hub 14 a.

In the present embodiment, as shown in fig. 8, recesses 10B are formed on both left and right surfaces of a rib 10A of the gear 10, and the clutch pistons 31 of the multiple disc clutches C1, C2 and a piston chamber S defined by the clutch pistons 31 are respectively fitted into the recesses 10B.

As shown in fig. 10, the clutch piston 31 is a circular plate-like member, and the engine shaft 3 passes through a circular hole 31a formed in the center thereof. Therefore, the clutch piston 31 is movable in the axial direction along the engine shaft 3, and on one end surface (the surface on the side facing the rib 10A of the gear 10), as shown in fig. 10, three convex portions 31A in the shape of a sector are integrally provided in a protruding manner at equal angular intervals (120 ° intervals) in the circumferential direction. Further, a sealing material 32 such as rubber is fixedly attached to the periphery of each projection 31A by burning.

On the other hand, on the end surface of the rib 10A of the gear 10 (the surface facing the clutch piston 31), as shown in fig. 9, fan-shaped recesses 10B having the same shape as the convex portions 31A of the clutch piston 31 are formed at equal angular intervals in the circumferential direction, and the convex portions 31A of the clutch piston 31 are fitted into the recesses 10B, whereby three piston chambers S are formed in the circumferential direction by the concave portions 10B and the convex portions 31A. As will be described later, the piston chambers S are supplied with pressurized oil, but the peripheries of the piston chambers S are sealed by the seal members 32 fixed to the peripheries of the convex portions 31A of the clutch piston 31, and therefore, the pressurized oil from the piston chambers S is reliably prevented from leaking. In the multi-plate clutches C1 and C2, the piston chambers S are formed so as to be circumferentially different from each other (i.e., so as not to overlap each other by 60 ° in phase).

As shown in fig. 8, a circular hole-shaped oil passage 33 is formed in the center of the engine shaft 3, and oil holes 34 for supplying oil pressure are formed in 3 (only 1 in fig. 8) in the oil passage 33 so as to be inclined radially outward. As shown in fig. 9, each oil hole 34 is opened to each recess 10B (each piston S chamber) formed in the rib 10A of the gear 10. Further, circular holes 35 for discharging hydraulic oil are formed in the respective concave portions 10B (the respective piston chambers S) formed on the respective surfaces of the rib 10A of the gear 10, and as shown in fig. 4, check valves 36 for discharging pressurized oil are provided in the respective circular holes 35.

As shown in fig. 2 and 4, the clutch piston 31 abuts against the innermost clutch plate 28, and holds the plurality of clutch plates 28 and clutch discs 29 between the clutch guide 27 and a stopper 37 fixed to the clutch hub 14 a. The clutch piston 31 is biased inward (in a direction away from the clutch plate 28) by a plurality of return springs 38 arranged in the circumferential direction.

In the clutch C1 configured as described above, when pressure oil is supplied to each piston chamber S from an unillustrated hydraulic pump through the oil passage 33 and the oil holes 34 of the engine shaft 3 in a state where the engine shaft 3 is rotating, the clutch piston 31 moves outward (rightward in fig. 2) due to the oil pressure, and presses the plurality of clutch plates 28 and the clutch discs 29 stacked alternately in the axial direction, thereby sandwiching the clutch plates 28 and the clutch discs 29 between the stopper 37 and the clutch plates 28 and the clutch discs 29. Therefore, the multi-plate clutch C1 is in a connected (ON) state, and a frictional force is generated between the adjacent clutch plates 28 and clutch discs 29, and the engine shaft 3 and the gear 10 are coupled to the transmission gear 14 by the frictional force. Therefore, the rotation of the engine shaft 3 is transmitted to the counter shaft 4 through the transmission gears 14 and 15 of the low-speed transmission gear train GL. When the supply of the pressure oil to the piston chamber S of the multi-plate clutch C1 is interrupted, the clutch piston 31 is separated from the clutch plate 28 by the biasing force of the return spring 38, and therefore the multi-plate clutch C1 is in the disengaged (OFF) state, and the rotation of the engine shaft 3 is not transmitted to the counter shaft 4. Similarly, in the multi-plate clutch C2, when the multi-plate clutch C2 is engaged (ON), the rotation of the engine shaft 3 is transmitted to the counter shaft 4 via the high-speed transmission gear train GH. When the multiple disc clutch C2 is disengaged (OFF), the rotation of the engine shaft 3 is not transmitted to the counter shaft 4.

As described above, in the power transmission device 1 of the present embodiment, the multiple disc clutches C1 and C2 are respectively disposed on the left and right sides of the gear 10 integrally formed on the engine shaft 3, the recesses 10B are respectively formed on the left and right sides of the rib 10A of the gear 10, and the clutch piston 31 of the multiple disc clutches C1 and C2 and the piston chamber S defined by the clutch piston 31 are respectively incorporated into the respective recesses 10B, so that the power transmission device 1 is reduced in axial dimension to achieve downsizing, compactness, and weight reduction.

In the present embodiment, the motor 7 and the generator 8 are disposed at substantially the same position in the axial direction, and therefore the overall axial dimension of the power transmission device 1 is reduced, and the size are reduced.

Further, in the present embodiment, since the multi-plate clutches C1 and C2 are disposed on the engine shaft 3 so as to switch between the low speed and the high speed, effective use of space, simplification of a torque transmission path, improvement of support rigidity for a high-speed rotating shaft, improvement of assemblability, and the like can be realized.

The present invention is not limited to the embodiments described above, and various modifications can be made within the scope of the technical ideas described in the specification and the drawings.

Claims

1. A power transmission device for a vehicle, comprising:

a first rotation shaft and a second rotation shaft arranged in parallel to each other;

a plurality of speed change gear trains that change and transmit rotation output from a drive source to the first rotary shaft to the second rotary shaft; and

a multi-plate clutch provided corresponding to each of the speed change gear trains,

the power transmission device for a vehicle is characterized in that,

the multiple disc clutches are disposed on both sides in the axial direction of a gear fixed to the first rotating shaft, and a clutch piston of each of the multiple disc clutches and a piston chamber defined by the clutch piston are respectively incorporated into both surfaces in the axial direction of a rib of the gear.

2. The vehicular power transmission device according to claim 1, characterized by being configured to: a low-speed transmission gear train and a high-speed transmission gear train are disposed on both sides of the gear in the axial direction, and the coupling of the first rotating shaft and the second rotating shaft by the low-speed transmission gear train or the high-speed transmission gear train is switched by the multi-plate clutch.

3. The vehicular power transmission device according to claim 1 or 2, characterized by being configured to: the clutch guide is attached to the rib of the gear by providing a cylindrical clutch guide for guiding axial movement of the clutch plates and the clutch discs, which are alternately stacked in the axial direction, inserting an engagement claw projecting from a part of each clutch guide into an engagement hole formed in the rib of the gear, and fixing the insertion end of the engagement claw by a snap ring.

4. The vehicular power transmitting apparatus according to claim 1 or 2, wherein concave portions are formed on both surfaces of the gear rib in the axial direction, convex portions protruding from a clutch piston of the multiple disc clutch are fitted into the concave portions, respectively, and the piston chambers are formed between the concave portions and the convex portions, respectively, and oil holes for providing hydraulic pressure and holes for discharging hydraulic pressure are opened in the piston chambers, respectively.

5. The vehicular power transmitting apparatus according to claim 3, wherein concave portions are formed on both surfaces of the gear rib in the axial direction, convex portions projecting from a clutch piston of the multiple disc clutch are fitted into the concave portions, respectively, and the piston chambers are formed between the concave portions and the convex portions, respectively, so that oil holes for supplying hydraulic pressure and holes for discharging hydraulic pressure are formed in the piston chambers, respectively.

6. The vehicular power transmitting apparatus according to claim 4, wherein a seal material is fixed around a projection provided on the clutch piston.

7. The vehicular power transmitting apparatus according to claim 5, wherein a seal material is fixed around a projection provided on the clutch piston.

8. The vehicular power transmitting apparatus according to claim 4, characterized in that a check valve is provided in the hydraulic pressure discharge hole.

9. The vehicular power transmitting apparatus according to claim 5, characterized in that a check valve is provided in the hydraulic pressure discharge hole.