CN111609050A

CN111609050A - Launch clutch for a transmission

Info

Publication number: CN111609050A
Application number: CN202010590406.5A
Authority: CN
Inventors: 万全喜; 孙康笑; 范述鑫; 马长智
Original assignee: Shengrui Transmission Co Ltd
Current assignee: Shengrui Transmission Co Ltd
Priority date: 2020-06-24
Filing date: 2020-06-24
Publication date: 2020-09-01

Abstract

The invention relates to the technical field of automatic transmissions, and provides a starting clutch for a transmission. The starting clutch comprises a piston device and a friction device, wherein the friction device comprises a friction plate set, an inner hub and an outer hub, and an oil cavity is formed between the inner hub and the friction plate set; the piston device comprises a main piston and a balance piston, and a balance piston cavity is formed between the main piston and the balance piston; the main piston is arranged on the piston support, an oil supply part is arranged on the piston support, an oil supply channel is arranged on the oil supply part, a sealing steel sleeve is arranged on the inner side of the piston support, and a sealing part is arranged on the sealing steel sleeve. During this application fuel feeding, hydraulic oil enters into balanced piston intracavity through first oil circuit partly, and in another part directly entered into the oil pocket of friction disc group, increased the efficiency that hydraulic oil supplyed, sealed steel bushing extended to the inboard of fuel feeding portion to be provided with first sealing member, prevent that hydraulic oil from flowing away from the clearance of clutch, avoid the waste of hydraulic oil, simultaneously, ensure the fuel feeding volume of friction disc group.

Description

Launch clutch for a transmission

Technical Field

The invention relates to the technical field of automatic transmissions, in particular to a starting clutch for a transmission.

Background

An automotive transmission is a set of transmission devices for coordinating the rotational speed of an engine and the actual driving speed of wheels, and is used for exerting the best performance of the engine. The transmission can generate different gear ratios between an engine and wheels during the running process of the automobile, and the transmission of rotating speeds of different gears is realized.

The manual transmission mainly comprises gears and a rotating shaft, and the speed change and torque change are generated by different gear combinations; the automatic transmission AT consists of a hydraulic torque converter, a planetary gear and a hydraulic control system, and achieves speed and torque changing through a hydraulic transmission and gear combination mode.

Among them, the automatic transmission has advantages of comfortable driving, reducing fatigue of driver, etc., and has become a development direction of modern car configuration. The automatic transmission utilizes a planetary gear mechanism to change speed, can automatically change speed according to the degree of an accelerator pedal and the change of vehicle speed, and a driver only needs to operate the accelerator pedal to control the vehicle speed, so that the driver can watch road traffic with full attention without being shifted to be in a mess.

The automatic transmission includes a plurality of planetary gear assemblies and a plurality of shift elements, wherein the shift elements include clutches and brakes. The transmission relationship of each planetary transmission assembly is changed through the gear shifting unit, so that the automatic transmission outputs different rotating speeds. In the case of an automatic transmission for a hybrid vehicle, a starting clutch is also provided for starting and stopping the vehicle. One side of the starting clutch is provided with a main piston, a balance piston is arranged in the main piston, and hydraulic oil is introduced to one side, far away from the starting clutch, of the main piston to control the starting clutch to be closed. Meanwhile, a balance piston cavity is further formed in the main piston, the balance piston is arranged in the balance piston cavity, and hydraulic oil enters the balance piston cavity through another pipeline to achieve the effect of balancing the pressure of the main piston.

When the starting clutch works, the friction plate and the steel sheet rub against each other quickly, so that the friction plate set of the starting clutch is heated quickly, and the heat of the starting clutch is large. Therefore, hydraulic oil needs to be introduced into the oil cavity facing the friction plate set to play a role in cooling and lubricating the friction plate set. However, in the prior art, hydraulic oil needs to enter the oil cavity of the balance piston first, when the oil cavity of the balance piston is filled, part of the hydraulic oil enters the oil cavity of the friction plate set again, the hydraulic oil is not filled in time, the temperature of the friction plates is increased, and most of the hydraulic oil flows away through gaps in the automatic transmission, so that the hydraulic oil is wasted.

Disclosure of Invention

In order to solve the above technical problem or at least partially solve the above technical problem, the present invention provides a starting clutch for a transmission.

The starting clutch for the transmission comprises a piston device and a friction device, wherein the friction device comprises a friction plate set, an inner hub and an outer hub are respectively arranged on an inner ring and an outer ring of the friction plate set, and an oil cavity is formed between the periphery of the inner hub and the friction plate set;

the piston device comprises a main piston and a balance piston, wherein the main piston is used for being supported on the side face of the friction plate set, the balance piston is arranged in the main piston, the main piston is in sliding fit with the balance piston, a balance piston cavity is formed between the main piston and the balance piston, and the balance piston cavity is communicated with a first oil path of the clutch;

the main piston is arranged on the piston support, the piston support faces towards the direction of the friction plate set is extended to be provided with an oil supply part, the oil supply part is provided with an oil supply channel communicated with the oil cavity, the oil supply channel is communicated with the first oil way, the inner side of the piston support is provided with a sealing steel sleeve, the sealing steel sleeve faces towards the direction of the friction plate set is extended to be provided with a sealing part, the sealing part is arranged on the inner side of the oil supply part, and a first sealing element is arranged between the oil supply part and the sealing part.

Optionally, the main piston is in sliding fit with the piston support along an axial direction thereof, a main piston cavity is formed between one side of the main piston, which is far away from the friction plate set, and the piston support, a second oil passage is arranged between the sealing steel sleeve and the piston support, and an oil hole for communicating the second oil passage with the main piston cavity is arranged on the piston support.

Optionally, two second sealing elements are arranged between the piston support and the sealing steel sleeve in parallel, and the second oil path is arranged between the two second sealing elements.

Optionally, the piston support includes inner skleeve, outer sleeve and adapter sleeve, the adapter sleeve is connected the inner skleeve with the outer sleeve is kept away from one side of friction disc group, the inner skleeve sets up the periphery of sealed steel bushing, inner skleeve, outer sleeve and the adapter sleeve encloses and is used for the installation the annular mounting groove of main piston, the oil feed portion by the inner skleeve orientation the direction of friction disc group extends and forms.

Optionally, an oil passage is arranged on the balance piston, and hydraulic oil in the balance piston cavity enters the oil cavity through the oil passage.

Optionally, the balance piston cavity is further connected with a third oil path, the third oil path is simultaneously communicated with the oil supply channel, and when the starting clutch is in a working state, both the first oil path and the third oil path are opened; when the starting clutch is in a non-working state, the first oil path is closed, and the third oil path is opened.

Optionally, the inner wall of friction plate group is equipped with the interior latch of multiunit along its circumference direction interval, and every adjacent is two sets of form the draw-in groove between the interior latch, the periphery of interior hub is equipped with a plurality of outer calorie of posts along its circumference direction interval, every outer calorie of post corresponds one the draw-in groove, just the quantity of outer calorie of post is less than the quantity of draw-in groove, not with outer calorie of post corresponds the draw-in groove forms the oil pocket, the oil pocket with oil supply channel's position is relative.

Optionally, a clamp spring is arranged on the periphery of the oil supply portion, and the clamp spring is supported on one side, close to the friction plate set, of the balance piston.

Optionally, a first through hole is formed in the sealing steel sleeve, a second through hole is formed in the piston support, the first oil path, the first through hole, the second through hole and the balance piston cavity are sequentially communicated, and the first oil path is communicated with the oil supply channel through the first through hole.

Optionally, a return spring is arranged between the main piston and the balance piston.

Compared with the prior art, the technical scheme provided by the embodiment of the application has the following advantages:

the oil cavity of the friction plate set is directly communicated with the first oil way through the oil supply channel, during oil supply, hydraulic oil enters the balance piston cavity through one part of the first oil way, the other part of the hydraulic oil directly enters the oil cavity of the friction plate set, the efficiency of hydraulic oil supplement is increased, the friction plate set is lubricated in time, the temperature of the friction plate set is reduced, the service life of the friction plate set is prolonged, meanwhile, the sealing steel sleeve extends to the inner side of the oil supply part, a first sealing element is arranged between the sealing steel sleeve and the oil supply part, hydraulic oil is prevented from flowing away from the gap of the clutch, waste of the hydraulic oil is avoided, and meanwhile, the oil supply amount of the friction plate set is ensured.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present disclosure and together with the description, serve to explain the principles of the disclosure.

In order to more clearly illustrate the embodiments or technical solutions in the prior art of the present disclosure, the drawings used in the description of the embodiments or prior art will be briefly described below, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without inventive exercise.

FIG. 1 is a cross-sectional view of a launch clutch in accordance with an embodiment of the present invention;

FIG. 2 is an enlarged view at A in FIG. 1;

FIG. 3 is a schematic illustration of the positional relationship between the friction plate pack and the piston assembly when the launch clutch is engaged in accordance with an embodiment of the present invention;

FIG. 4 is an enlarged view at B in FIG. 3;

FIG. 5 is a schematic illustration of the position of the friction plate pack and piston arrangement when the launch clutch is not in operation in accordance with an embodiment of the present invention;

FIG. 6 is an enlarged view at C in FIG. 5;

FIG. 7 is a schematic structural view of a launch clutch in accordance with an embodiment of the present invention;

FIG. 8 is a schematic view of the arrangement of the oil chamber according to an embodiment of the present invention.

Reference numerals:

10. a friction plate set; 11. an inner hub; 12. an outer hub; 13. an oil chamber; 14. an inner latch; 15. an outer clamping column; 20. a primary piston; 21. a primary piston chamber; 30. a balance piston; 31. an oil passage; 32. a balance piston cavity; 40. a piston support; 41. an oil supply unit; 411. an oil supply passage; 42. a clamp spring; 43. an inner sleeve; 44. an outer sleeve; 45. connecting sleeves; 50. sealing the steel sleeve; 51. a sealing part; 511. a first seal member; 52. a second seal member; 60. a first oil passage; 61. a second oil passage; 62. a third oil passage; 70. a seal ring; 80. and a return spring.

Detailed Description

In order that the above objects, features and advantages of the present disclosure may be more clearly understood, aspects of the present disclosure will be further described below. It should be noted that the embodiments and features of the embodiments of the present disclosure may be combined with each other without conflict.

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present disclosure, but the present disclosure may be practiced in other ways than those described herein; it is to be understood that the embodiments disclosed in the specification are only a few embodiments of the present disclosure, and not all embodiments.

Referring to fig. 1 and 6, a starting clutch for a transmission according to an embodiment of the present application includes a piston device and a friction device.

The friction device comprises a friction plate group 10, and an inner hub 11 and an outer hub 12 are respectively arranged on the inner ring and the outer ring of the friction plate group 10. Specifically, the friction plate group 10 comprises a steel plate and a friction plate, wherein the steel plate is in circumferential limit connection with the outer hub 12, so that the steel plate and the outer hub 12 rotate synchronously; the friction plate and the inner hub 11 are in circumferential limit connection, so that the friction plate and the inner hub 11 rotate synchronously, and an oil cavity 13 is formed between the outer periphery of the inner hub 11 and the friction plate group 10 and used for lubricating the friction plate and the steel plate.

The piston arrangement comprises a main piston 20 for supporting at the side of the friction disc pack 10 and a balance piston 30 arranged inside the main piston 20. Specifically, a mounting cavity is provided on a side of the main piston 20 facing the friction plate group 10, the balance piston 30 is disposed in the mounting cavity, and an outer ring of the balance piston 30 is supported on an inner wall of the main piston 20. The master piston 20 is slidably engaged with the balance piston 30 and forms a balance piston chamber 32 with the balance piston 30, the balance piston chamber 32 communicating with the first oil passage 60 of the clutch. The main piston 20 and the balance piston 30 are in sliding fit along the axial direction of the transmission, the balance piston 30 does not move, and the main piston 20 moves relative to the balance piston 30 to control the friction plate group 10 to be closed or opened.

As shown in fig. 2, 4 and 6, the master piston 20 is disposed on a piston support 40, and the inner race of the balance piston 30 is in a limit fit with the piston support 40. The piston support 40 is provided with an oil supply 41 extending in the direction of the friction plate pack 10, and the balance piston 30 is preferably provided on the oil supply 41. The oil supply portion 41 is provided with an oil supply passage 411 communicated with the oil chamber 13 of the friction plate group 10, the oil supply passage 411 is communicated with the first oil passage 60, namely, one end of the oil supply passage 411 is communicated with the oil chamber 13 of the friction plate group 10, the other end is communicated with the first oil passage 60, oil is supplied to the oil chamber 13 of the friction plate group 10 through the first oil passage 60, and the first oil passage 60 is opened on a support member of the transmission, in some embodiments, the support member is the brake outer hub 12, namely, the first oil passage 60 is opened on the brake outer hub 12.

A seal steel sleeve 50 is provided inside the piston support 40, a seal portion 51 is provided in the seal steel sleeve 50 extending in the direction of the friction plate group 10, the seal portion 51 is provided inside the oil supply portion 41, and a first seal 511 is provided between the oil supply portion 41 and the seal portion 51. Wherein the sealing steel sleeve 50 is disposed between the piston support 40 and the support. Preferably, a mounting groove for mounting the first sealing member 511 is provided at a side of the sealing part 51 facing the oil supplier 41, and the mounting groove is provided at the sealing part 51 to make reasonable use of space and avoid lowering of strength of components. The first seal 511 is preferably a rectangular seal ring 70.

Further optimally, two second sealing elements 52 are arranged between the piston support 40 and the sealing steel sleeve 50 in parallel, and the second oil path 61 is arranged between the two second sealing elements 52, so that hydraulic oil in the second oil path 61 is prevented from flowing away from a gap between the piston support 40 and the sealing steel sleeve 50, and the sealing effect is improved. Specifically, the sealing steel sleeve 50 is provided with an annular groove for mounting the second seal 52. The second sealing element 52 is arranged on the sealing steel sleeve 50, so that the occupied space is effectively saved, the design difficulty is reduced, and meanwhile, the strength of the piston support 40 is prevented from being influenced. The second seal 52 is preferably a rectangular seal ring 70.

Referring to fig. 1 and 2, the main piston 20 is slidably engaged with the piston support 40 along an axial direction thereof, a main piston cavity 21 is formed between one side of the main piston 20, which is far away from the friction plate set 10, and the piston support 40, a second oil passage 61 communicated with the main piston cavity 21 is provided between the sealing steel sleeve 50 and the piston support 40, the second oil passage 61 is communicated with an oil supply line of the transmission, and an oil hole for communicating the second oil passage 61 with the main piston cavity 21 is provided on the piston support 40. And in order to prevent hydraulic oil from flowing away through the gap between the main piston 20 and the piston support 40, a seal ring 70 is provided between the main piston 20 and the piston support 40, and the axial direction of the seal ring 70 is the same as the axial direction of the transmission.

As shown in fig. 3 to fig. 6, the balance piston 30 is provided with an oil passage 31, and hydraulic oil in the balance piston cavity 32 enters the friction plate set 10 through the oil passage 31 and flows to the oil cavity 13 to lubricate the friction plate set 10. Oil is simultaneously supplied toward friction plate group 10 through oil passage 31 and oil supply passage 411, increasing oil supply efficiency.

Further preferably, as shown in fig. 4 and 6, the balance piston chamber 32 is also connected with a third oil passage 62, and the third oil passage 62 is simultaneously communicated with the oil supply passage 411. It should be noted that the first oil path 60 and the third oil path 62 are two different oil paths with different cross sections, and have no mutual influence. And when the starting clutch is in the working state, the first oil path 60 and the third oil path 62 are both opened, and oil is simultaneously supplied to the oil supply passage 411 through the first oil path 60 and the third oil path 62, so that the oil supply efficiency is increased. When the starting clutch is in a non-working state, the first oil path 60 is closed, the third oil path 62 is opened, that is, when the starting clutch is in a non-working state, oil is supplied to the balance piston cavity 32 and the oil supply channel 411 through the third oil path 62, hydraulic oil enters the oil cavity 13 of the friction plate set 10 through the oil supply channel 411, hydraulic oil in the balance piston cavity 32 flows to the friction plate set 10 through the oil channel 31, so that the friction plate set 10 plays a role in lubrication at ordinary times, and waste of the hydraulic oil is avoided. Preferably, the oil supply amount of the third oil passage 62 should be lower than that of the first oil passage 60, further reducing the waste of the hydraulic oil. The closing and opening of the first oil path 60 can be controlled by an electromagnetic valve, and the manner of controlling the on-off of the oil path by the electromagnetic valve is mature in the prior art, so that the description is not repeated.

In use, the first, second and

third oil passages

60, 61, 62 are all open, supplying oil through the first and

third oil passages

60, 62 towards the balance piston 30 and the oil chamber 13 of the friction plate pack 10, and through the second oil passage 61 towards the main piston chamber 21. The balance piston 30, among other things, serves to balance the main piston 20. After the oil is supplied to the main piston cavity 21, the hydraulic oil pushes the main piston 20 to move towards the direction of the friction plate set 10, and the friction plate set 10 is closed, and it is noted that, as shown in fig. 3 and 4, when the friction plate set 10 is closed, the end surface of the main piston 20 is completely attached to the end surface of the friction plate set 10, so that a sealing effect is ensured, the hydraulic oil is prevented from flowing out from a gap between the main piston 20 and the friction plate set 10, it is ensured that the hydraulic oil introduced into the friction plate set 10 meets the cooling requirement, and further the performance of the transmission is ensured. A return spring 80 is provided between the main piston 20 and the balance piston 30. When the main piston cavity 21 is decompressed, the return spring 80 pushes the main piston 20 to return, and the friction plate group 10 is opened.

The oil cavity 13 of the friction plate group 10 is directly communicated with the first oil channel 60 through the oil supply channel 411, during oil supply, one part of hydraulic oil enters the balance piston cavity 32 through the first oil channel 60, the other part of hydraulic oil directly enters the oil cavity 13 of the friction plate group 10, the efficiency of hydraulic oil supplement is increased, the friction plate group 10 is lubricated in time, the temperature of the friction plate group 10 is reduced, the service life of the friction plate group 10 is prolonged, meanwhile, the sealing steel sleeve 50 extends to the inner side of the oil supply part 41, and a first sealing element 511 is arranged between the sealing steel sleeve 50 and the oil supply part 41, the hydraulic oil is prevented from flowing away from a gap of a clutch, the waste of the hydraulic oil is avoided, and meanwhile, the oil supply quantity of the friction plate group 10.

As shown in fig. 1 to 6, the piston support 40 includes an inner sleeve 43, an outer sleeve 44 and a connecting sleeve 45, the connecting sleeve 45 is connected to one side of the inner sleeve 43 and the outer sleeve 44 away from the friction plate group 10, the inner sleeve 43 is disposed on the periphery of the sealing steel sleeve 50, the inner sleeve 43, the outer sleeve 44 and the connecting sleeve 45 enclose an annular mounting groove for mounting the main piston 20, the oil supply portion 41 is formed by extending the inner sleeve 43 towards the direction of the friction plate group 10, and the inner ring of the balance piston 30 is in limit fit with the oil supply portion 41. Wherein, the inner ring of the main piston 20 is arranged on the periphery of the inner sleeve 43 in a sliding manner, the outer ring of the main piston 20 is arranged on the inner wall of the outer sleeve 44 in a sliding manner, and the connecting positions of the main piston 20, the inner sleeve 43 and the outer sleeve 44 are all provided with sealing structures, so that the leakage of hydraulic oil in the main piston cavity 21 is avoided.

As shown in fig. 2, a clamp spring 42 is disposed on the periphery of the oil supply unit 41, and the clamp spring 42 is supported on one side of the balance piston 30 close to the friction plate set 10, so as to facilitate positioning of the balance piston 30, effectively utilize the internal space of the piston support 40, and reduce the complexity of the limiting structure.

As shown in fig. 2, a first through hole is formed in the sealing steel sleeve 50, a second through hole is formed in the piston support 40, the first oil path 60, the first through hole, the second through hole and the balance piston cavity 32 are sequentially communicated, and the first oil path 60 is communicated with the oil supply passage 411 through the first through hole. Through set up the through-hole on piston brace 40 and sealing steel bushing 50 for the circulation of hydraulic oil avoids additionally setting up the hydraulic circuit, saves space and occupies.

Referring to fig. 7 and 8, a plurality of sets of inner latches 14 are arranged on the inner wall of the friction plate set 10 at intervals along the circumferential direction, a clamping groove is formed between every two adjacent sets of inner latches 14, a plurality of outer clamping columns 15 are arranged on the periphery of the inner hub 11 at intervals along the circumferential direction, each outer clamping column 15 corresponds to one clamping groove, the number of the outer clamping columns 15 is smaller than that of the clamping grooves, an oil chamber 13 is formed in the clamping groove which is not corresponding to the outer clamping column 15, and the oil chamber 13 is opposite to the oil supply passage 411.

Specifically, the friction plate group 10 includes a plurality of steel sheets and friction plates, the steel sheets and the friction plates are arranged alternately, so that one friction plate is arranged between every two steel sheets, one steel sheet is arranged between every two friction plates, the friction plates are in circumferential limit connection with the inner hub 11, the steel sheets are in circumferential limit connection with the outer hub 12, the inner clamping teeth 14 are arranged on the side of each friction plate, the positions of the inner clamping teeth 14 on each friction plate along the circumferential direction are opposite, a clamping groove is formed, the outer clamping columns 15 of the inner hub 11 stretch into the clamping groove, and the inner hub 11 and the friction plates are enabled to rotate synchronously. And some draw-in grooves do not correspond outer calorie of post 15, and each outer calorie of post 15 is not evenly arranged along the circumferential direction of interior hub 11 promptly, and the distance between some adjacent two outer calories of posts is twice between other adjacent two outer calories of posts. This design facilitates the stroke of the oil chamber 13 so that the hydraulic oil can quickly lubricate the friction plate pack 10.

It is noted that, in this document, relational terms such as "first" and "second," and the like, may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

The foregoing are merely exemplary embodiments of the present disclosure, which enable those skilled in the art to understand or practice the present disclosure. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the disclosure. Thus, the present disclosure is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A starting clutch for a transmission is characterized by comprising a piston device and a friction device, wherein the friction device comprises a friction plate set (10), an inner hub (11) and an outer hub (12) are respectively arranged on an inner ring and an outer ring of the friction plate set (10), and an oil cavity (13) is formed between the periphery of the inner hub (11) and the friction plate set (10);

the piston device comprises a main piston (20) and a balance piston (30), wherein the main piston (20) is used for being supported on the side surface of the friction plate set (10), the balance piston (30) is arranged inside the main piston (20), the main piston (20) is in sliding fit with the balance piston (30) and forms a balance piston cavity (32) with the balance piston (30), and the balance piston cavity (32) is communicated with a first oil path (60) of the clutch;

main piston (20) set up on piston support (40), piston support (40) orientation the direction extension of friction disc group (10) is equipped with oil feed portion (41), oil feed portion (41) be equipped with fuel feeding channel (411) of oil pocket (13) intercommunication, fuel feeding channel (411) with first oil circuit (60) intercommunication, the inboard of piston support (40) is equipped with sealed steel bushing (50), sealed steel bushing (50) orientation the direction extension of friction disc group (10) is equipped with sealing (51), sealing (51) set up the inboard of oil feed portion (41), oil feed portion (41) with be equipped with first sealing member (511) between sealing (51).

2. The starting clutch for the transmission according to claim 1, wherein the main piston (20) and the piston support (40) are in sliding fit along an axial direction of the main piston, a main piston cavity (21) is formed between one side of the main piston (20) far away from the friction plate set (10) and the piston support (40), a second oil passage (61) is arranged between the sealing steel sleeve (50) and the piston support (40), and an oil hole for communicating the second oil passage (61) with the main piston cavity (21) is arranged on the piston support (40).

3. The starting clutch for a transmission according to claim 2, characterized in that two second seals (52) are provided in parallel between the piston support (40) and the sealing steel sleeve (50), and the second oil passage (61) is provided between the two second seals (52).

4. The starting clutch for the transmission as claimed in claim 1, characterized in that the piston support (40) comprises an inner sleeve (43), an outer sleeve (44) and a connecting sleeve (45), the connecting sleeve (45) is connected to the inner sleeve (43) and the outer sleeve (44) on the side away from the friction plate set (10), the inner sleeve (43) is arranged on the periphery of the sealing steel sleeve (50), the inner sleeve (43), the outer sleeve (44) and the connecting sleeve (45) enclose an annular mounting groove for mounting the main piston (20), and the oil supply portion (41) is formed by extending the inner sleeve (43) in the direction towards the friction plate set (10).

5. The starting clutch for a transmission according to claim 1, characterized in that an oil passage (31) is provided on the balance piston (30), and hydraulic oil in the balance piston chamber (32) enters the oil chamber (13) through the oil passage (31).

6. The starting clutch for a transmission according to claim 5, characterized in that a third oil passage (62) is further connected to the balance piston chamber (32), the third oil passage (62) is simultaneously communicated with the oil supply passage (411), and when the starting clutch is in an operating state, the first oil passage (60) and the third oil passage (62) are both opened; when the starting clutch is in a non-working state, the first oil path (60) is closed, and the third oil path (62) is opened.

7. The starting clutch for the transmission as claimed in claim 1, wherein the inner wall of the friction plate set (10) is provided with a plurality of sets of inner snap teeth (14) at intervals along the circumferential direction thereof, a snap groove is formed between each two adjacent sets of inner snap teeth (14), the outer periphery of the inner hub (11) is provided with a plurality of outer snap columns (15) at intervals along the circumferential direction thereof, each outer snap column (15) corresponds to one snap groove, the number of the outer snap columns (15) is smaller than that of the snap grooves, the snap grooves which do not correspond to the outer snap columns (15) form the oil chamber (13), and the oil chamber (13) is opposite to the oil supply passage (411).

8. Starting clutch for a transmission according to claim 1, characterized in that the oil feed is provided with a circlip (42) on its periphery, which circlip (42) is supported on the side of the balance piston (30) close to the set of friction plates (10).

9. The starting clutch for the transmission according to claim 1, wherein a first through hole is formed in the sealing steel sleeve (50), a second through hole is formed in the piston support (40), the first oil path (60), the first through hole, the second through hole and the balance piston cavity (32) are sequentially communicated, and the first oil path (60) is communicated with the oil supply channel (411) through the first through hole.

10. Launch clutch for a transmission according to claim 1, characterised in that a return spring (80) is provided between the main piston (20) and the balance piston (30).