JP2016164449A - Wet multiple disc clutch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wet multiple disc clutch which can sufficiently supply a lubricant to a thrust bearing which is interposed between a clutch disc and a piston.SOLUTION: A plurality of clutch discs 103, 104 are arranged while being aligned in a rotation axial line direction. A hydraulic chamber 106 is formed at one side of the rotation axial line direction with respect to a piston 105. The piston 105 receives hydraulic pressure supplied to the hydraulic chamber 106, and presses a plurality of the clutch discs 103, 104 by the hydraulic pressure from one side of the rotation axial line direction via a thrust bearing 107. An oil hole 131 which penetrates the piston 105 in the rotation axial line direction is formed at the piston 105 in a position opposing the thrust bearing 107 in the rotation axial line direction.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a wet multi-plate clutch.

  As a transmission mounted on a vehicle, an automatic transmission in which a gear ratio is automatically changed, such as AT (Automatic Transmission) and CVT (Continuously Variable Transmission), is known. In a vehicle equipped with an automatic transmission, power from a drive source such as an engine is input to the automatic transmission via a torque converter.

  The automatic transmission includes a brake for braking the rotating element and a clutch for connecting the rotating element and another rotating element. The brake and clutch must absorb the differential rotation between the rotating elements, and supply of lubricating oil is necessary to prevent seizure due to absorption of the differential rotation.

  The CVT has a configuration in which an endless belt is wound around an input-side primary pulley and an output-side secondary pulley. In one example, the CVT is used to switch the rotation direction of power transmitted to the primary pulley. A switching mechanism is provided. The switching mechanism includes a planetary gear mechanism, a forward brake, and a reverse clutch.

  The sun gear of the planetary gear mechanism is supported by an input shaft (input shaft) so as not to be relatively rotatable. The carrier (planetary carrier) of the planetary gear mechanism is supported by the input shaft so as to be relatively rotatable. The ring gear of the planetary gear mechanism is provided so as to be rotatable integrally with the primary pulley. The forward brake is engaged / released by hydraulic pressure to brake / allow carrier rotation. The reverse clutch is engaged / released to connect / disconnect the sun gear and the carrier. When the vehicle moves forward, the reverse clutch is released and the forward brake is engaged. As a result, the carrier is braked and the primary pulley rotates in the opposite direction to the input shaft. On the other hand, when the vehicle moves backward, the forward brake is released and the reverse clutch is engaged. Thereby, the sun gear and the carrier are connected, and the primary pulley rotates in the same direction as the input shaft.

  The reverse clutch includes a plurality of clutch disks provided integrally with the sun gear, a plurality of clutch plates provided integrally with the carrier and arranged alternately with the clutch disks in the axial direction, and the clutch plate And a piston for pressing the. A thrust bearing is interposed between the clutch plate and the piston in order to receive a thrust load due to the pressure of the piston and a differential rotation between the clutch plate and the piston. When the vehicle moves backward, the piston presses the clutch plate via the thrust bearing by hydraulic pressure, and the clutch plate and the clutch disk are pressed against each other.

  In the input shaft, a lubricating oil passage is formed along the axis thereof, and an orifice (distribution oil passage) is formed around the lubricating oil passage. The orifice communicates with the lubricating oil passage and is opened on the peripheral surface of the input shaft. The thrust bearing is supplied with lubricating oil distributed through the orifice from the lubricating oil passage.

JP 2004-176890 A

  Many torque converters with a lock-up clutch are used for torque converters in order to improve fuel efficiency. In this torque converter with a lockup clutch, an engagement side oil chamber and a release side oil chamber are formed on both sides of the lockup clutch. For example, hydraulic pressure is selectively supplied from a lockup control valve to the engagement side oil chamber and the release side oil chamber. The lockup control valve is provided with an input port for receiving a lockup signal pressure. When the lockup signal pressure is less than a predetermined value, hydraulic pressure is supplied from the lockup control valve to the release side oil chamber. When the lockup signal pressure is equal to or higher than a predetermined value, the hydraulic pressure is supplied from the lockup control valve to the engagement side oil chamber. The lockup clutch is engaged / released due to a hydraulic pressure difference between the engagement side oil chamber and the release side oil chamber.

  In the above-described example of CVT, the lockup signal pressure is supplied to the lubricating oil passage. For this reason, when the lockup clutch is engaged, the oil pressure of a predetermined value or more is supplied to the lubricating oil passage and the lubricating oil passage is sufficiently supplied, but when the lockup clutch is released, the lubricating oil passage is supplied. The supplied hydraulic pressure is less than a predetermined value, and the lubricating oil is not sufficiently supplied to the lubricating oil passage. Since the lockup clutch is not engaged when the vehicle is moving backward, there is a possibility that the lubricating oil may not be sufficiently supplied to the thrust bearing interposed between the clutch plate and the piston when the reverse clutch is engaged.

  An object of the present invention is to provide a wet multi-plate clutch capable of sufficiently supplying lubricating oil to a thrust bearing interposed between a clutch plate and a piston.

  In order to achieve the above object, a wet multi-plate clutch according to the present invention includes a plurality of clutch plates arranged side by side in the rotation axis direction, and a thrust arranged on one side of the rotation axis direction with respect to the plurality of clutch plates. A bearing is provided so as to be movable in the direction of the rotation axis, and is formed on one side of the piston for applying a load from one side to the plurality of clutch plates via a thrust bearing, and acts on the piston. An oil hole that penetrates the piston in the direction of the rotation axis is formed in the piston at a position facing the thrust bearing in the direction of the rotation axis.

  According to this configuration, the plurality of clutch plates are arranged side by side in the rotation axis direction. A hydraulic chamber is formed on one side in the rotational axis direction with respect to the piston. The piston receives hydraulic pressure supplied to the hydraulic chamber, and presses the plurality of clutch plates via thrust bearings from one side in the rotational axis direction by the hydraulic pressure.

  The piston is formed with an oil hole penetrating the piston in the rotation axis direction at a position facing the thrust bearing in the rotation axis direction. For this reason, even when the wet multi-plate clutch is engaged (when the clutch plate is pressed by the piston), even if the lubricating oil from the lubricating oil passage is not sufficiently supplied to the space on the clutch plate side with respect to the piston, The hydraulic oil supplied to the hydraulic chamber is supplied to the bearing through the oil hole. As a result, hydraulic oil as lubricating oil can be sufficiently supplied to the thrust bearing.

  In addition, when hydraulic oil is supplied to the hydraulic chamber for the first time, air usually remains in the hydraulic chamber and an air pocket is generated in the upper portion of the hydraulic chamber. If the oil hole is formed at a position communicating with the air reservoir, the air in the hydraulic chamber can escape to the space on the clutch plate side with respect to the piston through the oil hole. Therefore, the hydraulic chamber can be filled with hydraulic oil, and the hydraulic pressure can be applied to the entire piston. As a result, when the wet multi-plate clutch is engaged, the piston can be prevented from tilting with respect to the rotation axis direction, and the clutch plate can be favorably pressed by the piston.

  Furthermore, since oil can be circulated between the hydraulic chamber and the space on the clutch plate side, it is possible to suppress the same oil from staying in the hydraulic chamber.

  The thrust bearing may include a cage that holds a plurality of rolling elements (for example, needle rollers) and a race that abuts the cage in the rotational axis direction, and the race may be held by a piston.

  In this configuration, since the race comes into contact with the piston and the oil hole formed in the piston is closed by the race, it is possible to prevent the hydraulic oil in the hydraulic chamber from being excessively removed from the oil hole. As a result, the hydraulic pressure (engagement pressure) required for pressing the plurality of clutch plates by the piston can be stably secured. In addition, since hydraulic oil as lubricating oil can be directly supplied to the race from the oil hole, even if the race hits the piston and a force in the rotational direction (relative rotational force) is generated between the race and the piston, It is possible to suppress wear of the contact portion between the race and the piston.

  An oil retaining portion in which oil stays may be formed at the end portion on the clutch plate side in the oil hole by forming the sectional area larger than the sectional area of the portion other than the end portion.

  As a result, the oil can be retained in the oil retaining part, so that the oil can be supplied to the thrust bearing more satisfactorily.

  Moreover, the some oil hole may be formed at intervals in the circumferential direction, and the oil groove extended in the circumferential direction may be further formed so that each oil hole may be connected.

  By forming a plurality of oil holes, oil can be supplied to the thrust bearings uniformly in the circumferential direction. By forming the oil groove, oil can be supplied to the thrust bearing more evenly in the circumferential direction.

  According to the present invention, the lubricating oil can be sufficiently supplied to the thrust bearing.

1 is a skeleton diagram showing a configuration of a drive system including a continuously variable transmission incorporating a reverse brake according to an embodiment of the present invention. It is sectional drawing which cut | disconnected the reverse clutch by the plane containing a rotating shaft line. It is the figure which looked at the piston of the reverse clutch from the rotation axis direction.

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

<Configuration of drive system>

  FIG. 1 is a skeleton diagram showing a configuration of a drive system including a CVT 4 with a built-in reverse clutch C1 according to an embodiment of the present invention.

  The vehicle 1 is an automobile that uses an engine (E / G) 2 as a power source. The vehicle 1 is equipped with a torque converter 3 and a CVT (continuously variable transmission) 4.

  The engine 2 includes an E / G output shaft 21. The E / G output shaft 21 is rotated by the power generated by the engine 2.

  The torque converter 3 includes a pump impeller 31, a turbine runner 32, and a lockup clutch 33. An E / G output shaft 21 is connected to the pump impeller 31, and the pump impeller 31 is provided so as to be integrally rotatable about the same rotation axis as the E / G output shaft 21. The turbine runner 32 is provided to be rotatable about the same rotation axis as the pump impeller 31. The lockup clutch 33 is provided to directly connect / separate the pump impeller 31 and the turbine runner 32. When the lockup clutch 33 is engaged, the pump impeller 31 and the turbine runner 32 are directly connected, and when the lockup clutch 33 is released, the pump impeller 31 and the turbine runner 32 are separated.

  When the E / G output shaft 21 is rotated in a state where the lockup clutch 33 is released, the pump impeller 31 rotates. When the pump impeller 31 rotates, an oil flow from the pump impeller 31 toward the turbine runner 32 is generated. This oil flow is received by the turbine runner 32 and the turbine runner 32 rotates. At this time, the amplifying action of the torque converter 3 occurs, and a torque larger than the torque of the E / G output shaft 21 is generated in the turbine runner 32.

  In a state where the lockup clutch 33 is engaged, when the E / G output shaft 21 is rotated, the E / G output shaft 21, the pump impeller 31, and the turbine runner 32 are rotated together.

  An oil pump 5 is provided between the torque converter 3 and the CVT 4. The pump shaft of the oil pump 5 is provided so as to be rotatable integrally with the pump impeller 31. Accordingly, when the pump impeller 31 is rotated by the power of the engine 2, the pump shaft of the oil pump 5 is rotated and oil is discharged from the oil pump 5.

  The CVT 4 includes an input shaft 41, an output shaft 42, a belt transmission mechanism 43, and a forward / reverse switching mechanism 44.

  The input shaft 41 is connected to the turbine runner 32 of the torque converter 3 and is provided so as to be integrally rotatable about the same rotation axis as the turbine runner 32.

  The output shaft 42 is provided in parallel with the input shaft 41. An output gear 45 is supported on the output shaft 42 so as not to be relatively rotatable. The output gear 45 meshes with the ring gear 7 of the differential gear 6.

  The belt transmission mechanism 43 includes a primary shaft 51 coupled to the input shaft 41, a secondary shaft 52 provided in parallel with the primary shaft 51, a primary pulley 53 supported by the primary shaft 51 so as not to rotate relative to the primary shaft 51, and a secondary shaft. 52, a secondary pulley 54 supported so as not to be relatively rotatable, and a belt 55 wound around the primary pulley 53 and the secondary pulley 54.

  The primary pulley 53 is disposed so as to face the fixed sheave 61 fixed to the primary shaft 51 with the belt 55 sandwiched between the fixed sheave 61 and is supported by the primary shaft 51 so as to be movable in the axial direction but not to be relatively rotatable. 62. A piston 63 fixed to the primary shaft 51 is provided on the opposite side of the movable sheave 62 from the fixed sheave 61, and a piston chamber (hydraulic chamber) 64 is formed between the movable sheave 62 and the piston 63. Yes.

  The secondary pulley 54 is arranged so as to be opposed to the fixed sheave 65 fixed to the secondary shaft 52 with the belt 55 sandwiched between the fixed sheave 65 and supported on the secondary shaft 52 so as to be movable in the axial direction but not to be relatively rotatable. 66. A piston 67 fixed to the secondary shaft 52 is provided on the opposite side of the movable sheave 66 from the fixed sheave 61, and a piston chamber (hydraulic chamber) 68 is formed between the movable sheave 66 and the piston 67. Yes.

  The forward / reverse switching mechanism 44 is interposed between the input shaft 41 and the primary shaft 51 of the belt transmission mechanism 43. The forward / reverse switching mechanism 44 includes a planetary gear mechanism 71, a reverse clutch (reverse clutch) C1, and a forward brake (forward brake) B1.

  The planetary gear mechanism 71 includes a carrier 72, a sun gear 73, and a ring gear 74.

  The carrier 72 is supported by the input shaft 41 so as to be relatively rotatable. The carrier 72 rotatably supports a plurality of pinion gears 75. The plurality of pinion gears 75 are arranged on the circumference.

  The sun gear 73 is supported by the input shaft 41 so as not to be relatively rotatable, and is disposed in a space surrounded by the plurality of pinion gears 75. The gear teeth of the sun gear 73 mesh with the gear teeth of each pinion gear 75.

  The ring gear 74 is provided such that its rotational axis coincides with the axis of the primary shaft 51. A primary shaft 51 of the belt transmission mechanism 43 is connected to the ring gear 74. The gear teeth of the ring gear 74 are formed so as to collectively surround the plurality of pinion gears 75 and mesh with the gear teeth of each pinion gear 75.

  The reverse clutch C <b> 1 is provided between the carrier 72 and the sun gear 73.

  Forward brake B1 is provided between carrier 72 and a transmission case that accommodates torque converter 3 and CVT4.

  When the vehicle 1 moves forward, the reverse clutch C1 is released and the forward brake B1 is engaged. When the power of the engine 2 is input to the input shaft 41, the sun gear 73 rotates integrally with the input shaft 41 while the carrier 72 is stationary. Therefore, the rotation of the sun gear 73 is transmitted to the ring gear 74 while being reversed and decelerated. As a result, the ring gear 74 rotates, and the primary shaft 51 and the primary pulley 53 of the belt transmission mechanism 43 rotate together with the ring gear 74. The rotation of the primary pulley 53 is transmitted to the secondary pulley 54 via the belt 55 to rotate the secondary pulley 54 and the secondary shaft 52. Then, the output shaft 42 and the output gear 45 rotate integrally with the secondary shaft 52. When the rotation of the output gear 45 is transmitted to the ring gear 7 of the differential gear 6, the drive shafts 81 and 82 extending from the differential gear 6 to the left and right rotate, and the drive wheels (not shown) rotate, so that the vehicle moves forward. To do.

  On the other hand, when the vehicle 1 moves backward, the reverse clutch C1 is engaged and the forward brake B1 is released. When the power of the engine 2 is input to the input shaft 41, the carrier 72 and the sun gear 73 rotate integrally with the input shaft 41. Therefore, the rotation of the sun gear 73 is transmitted to the ring gear 74 without reversing the rotation direction. As a result, the ring gear 74 rotates in the direction opposite to that when the vehicle 1 moves forward, and the primary shaft 51 and the primary pulley 53 of the belt transmission mechanism 43 rotate together with the ring gear 74. The rotation of the primary pulley 53 is transmitted to the secondary pulley 54 via the belt 55 to rotate the secondary pulley 54 and the secondary shaft 52. Then, the output shaft 42 and the output gear 45 rotate integrally with the secondary shaft 52. When the rotation of the output gear 45 is transmitted to the ring gear 7 of the differential gear 6, the drive shafts 81 and 82 extending left and right from the differential gear 6 rotate in the opposite direction to the forward direction, and the drive wheels (not shown) rotate. As a result, the vehicle moves backward.

  In CVT4, the hydraulic pressure supplied to the piston chamber 64 of the primary pulley 53 and the piston chamber 68 of the secondary pulley 54 is controlled to change the groove widths of the primary pulley 53 and the secondary pulley 54, so that the gear ratio is continuously increased. It is changed steplessly.

  Specifically, when the gear ratio is lowered, the hydraulic pressure supplied to the piston chamber 64 of the primary pulley 53 is increased. As a result, the movable sheave 62 of the primary pulley 53 moves to the fixed sheave 61 side, and the interval (groove width) between the fixed sheave 61 and the movable sheave 62 is reduced. Accordingly, the winding diameter of the belt 55 around the primary pulley 53 is increased, and the interval (groove width) between the fixed sheave 65 and the movable sheave 66 of the secondary pulley 54 is increased. As a result, the pulley ratio between the primary pulley 53 and the secondary pulley 54 is reduced, and the gear ratio is reduced.

  When the gear ratio is increased, the hydraulic pressure supplied to the piston chamber 64 of the primary pulley 53 is decreased. Thereby, the thrust of the secondary pulley 54 with respect to the belt 55 becomes larger than the thrust of the primary pulley 53 with respect to the belt 55, the interval between the fixed sheave 65 and the movable sheave 66 of the secondary pulley 54 is reduced, and the fixed sheave 61 and the movable sheave The distance from 62 increases. As a result, the pulley ratio between the primary pulley 53 and the secondary pulley 54 is increased, and the gear ratio is increased.

  On the other hand, the thrust of the primary pulley 53 and the secondary pulley 54 needs to be large enough to prevent slippage between the primary pulley 53 and the secondary pulley 54 and the belt 55. Therefore, the hydraulic pressure supplied to the piston chamber 64 of the primary pulley 53 and the piston chamber 68 of the secondary pulley 54 is controlled so that a thrust according to the magnitude of the torque input to the input shaft 41 is obtained.

<Reverse clutch>

  FIG. 2 is a cross-sectional view of the reverse clutch C1 cut along a plane including the rotation axis C. FIG. FIG. 2 shows only one side with respect to the rotation axis C in the reverse clutch C1. FIG. 3 is a view of the piston 105 of the reverse clutch C1 as viewed from the direction of the rotation axis C.

  As described above, the reverse clutch C1 is provided between the carrier 72 and the sun gear 73, and is engaged / released to connect / disconnect the carrier 72 and the sun gear 73. The reverse clutch C1 includes a clutch drum 101, a clutch hub 102, a plurality of clutch plates 103 and 104, a piston 105, a hydraulic chamber 106, and a thrust bearing 107.

  The clutch drum 101 is provided integrally with the carrier 72 and has a substantially cylindrical shape with the rotation axis C as the center.

  The clutch hub 102 is provided integrally with the sun gear 73 and is disposed on the radially inner side of the clutch drum 101. The clutch hub 102 has a substantially cylindrical shape with the rotation axis C as the center and facing the clutch drum 101 with a space therebetween.

  A plurality of clutch plates (clutch plates) 103 are provided, each having an annular plate shape. The plurality of clutch plates 103 are arranged inside the clutch drum 101 at intervals in a direction parallel to the rotation axis C (rotation axis direction). The outer periphery of each clutch plate 103 is splined to the clutch drum 101.

  A plurality of clutch plates (clutch discs) 104 are provided, each having an annular plate shape. The plurality of clutch plates 104 are arranged inside the clutch hub 102 so as to be alternately arranged with the clutch plates 103 in the rotation axis direction. The inner peripheral portion of each clutch plate 104 is spline-fitted to the clutch hub 102.

  A stationary member 108 fixedly provided with respect to the case of the CVT 4 is formed with a recess 109 which is opposed to the clutch plates 103 and 104 from one side in the rotation axis direction and is recessed on one side. The piston 105 is disposed in the recess 109 and is provided so as to be movable in the rotation axis direction. The piston 105 includes a substantially cylindrical inner peripheral portion 111, a substantially cylindrical outer peripheral portion 112 surrounding the inner peripheral portion 111, one end portion of the inner peripheral portion 111, and one end portion of the outer peripheral portion 112. And a substantially disc-shaped pressing portion 113 erected between the two. Between the inner periphery 111 and the stationary member 108 and between the outer periphery 112 and the stationary member 108 are sealed in a liquid-tight manner by annular seals 114 and 115, respectively.

  The hydraulic chamber 106 is formed as a space defined by the piston 105, the stationary member 108, and the annular seals 114 and 115 between the piston 105 and the stationary member 108. Hydraulic pressure is supplied to the hydraulic chamber 106 through an oil passage (not shown), and the hydraulic pressure is released through the oil passage.

  The thrust bearing 107 is disposed between the clutch plates 103 and 104 and the piston 105 at a position facing the pressing portion 113 of the piston 105. The thrust bearing 107 includes a cage 121 that holds a plurality of rolling elements (for example, needle rollers), and a pair of races 122 and 123 that are disposed on both sides of the cage 121 in the rotational axis direction. . The race 122 on one side in the rotational axis direction is fitted on the inner peripheral portion 111 of the piston 105. The outer peripheral end portion of the race 122 abuts on the pressing portion 113 of the piston 105, and the inner peripheral end portion is opposed to the pressing portion 113 with a space therebetween. A through hole 124 is formed through the inner peripheral end of the race 122. The other-side race 123 is interposed between the clutch plate 103 and the cage 121 and is held by the clutch drum 101 together with the cage 121.

  When hydraulic pressure is supplied to the hydraulic chamber 106, the piston 105 moves to the clutch plates 103 and 104 side by the hydraulic pressure. As the movement of the piston 105 proceeds, the race 122 of the thrust bearing 107 comes into contact with the retainer 121, and the clutch plate 103 is pressed by the hydraulic pressure of the hydraulic chamber 106 via the piston 105 and the thrust bearing 107. 104 are pressed against each other. Thereby, engagement of the reverse clutch C1 is achieved. When the hydraulic pressure in the hydraulic chamber 106 is released from the state in which the reverse clutch C1 is engaged, the piston 105 moves to the side away from the clutch plate 103 by the elastic force of the return spring (not shown), and the reverse clutch C1 Is released.

  Lubricating oil flowing through a lubricating oil passage 126 formed on the rotation axis C of the input shaft 41 is supplied to the space 125 opposite to the hydraulic chamber 106 with respect to the piston 105. Specifically, a lubricating oil passage 126 is formed on the rotation axis C of the input shaft 41, and an orifice (distribution oil passage) 127 is formed around the lubricating oil passage 126. The orifice 127 communicates with the lubricating oil passage 126 and is opened on the peripheral surface of the input shaft 41. Lubricating oil flowing through the lubricating oil passage 126 is supplied to the space 125 through the orifice 127. Lubricating oil supplied from the orifice 127 to the space 125 is also supplied to the thrust bearing 107, and is also supplied between the race 122 and the piston 105 by forming the through hole 124 in the race 122.

  A lockup signal pressure is supplied to the lubricating oil passage 126. The lockup signal pressure is as described in the section “Problems to be Solved by the Invention”, and is the hydraulic pressure input to a lockup control valve (not shown). That is, in the torque converter 3, an engagement side oil chamber and a release side oil chamber are formed on both sides of the lockup clutch 33. For example, hydraulic pressure is selectively supplied from a lockup control valve to the engagement side oil chamber and the release side oil chamber. The lockup control valve is provided with an input port for receiving a lockup signal pressure. When the lockup signal pressure is less than a predetermined value, hydraulic pressure is supplied from the lockup control valve to the release side oil chamber. When the lockup signal pressure is equal to or higher than a predetermined value, the hydraulic pressure is supplied from the lockup control valve to the engagement side oil chamber.

  In the engaged state of the lockup clutch 33, a hydraulic pressure equal to or higher than a predetermined value is supplied to the lubricating oil passage 126 and the lubricating oil is sufficiently supplied to the lubricating oil passage 126. On the other hand, in the released state of the lockup clutch 33, the hydraulic pressure supplied to the lubricating oil passage 126 becomes less than a predetermined value, and the lubricating oil is not sufficiently supplied to the lubricating oil passage 126. Since the lockup clutch 33 is not engaged when the vehicle 1 is moving backward, the lubricating oil supplied to the space 125 from the orifice 127 is engaged between the piston 105 and the race 122 of the thrust bearing 107 when the reverse clutch C1 is engaged. There is a risk that it will not be adequately supplied.

  In order to solve this problem, a plurality of oil holes 131 are formed in the pressing portion 113 of the piston 105 at a portion where the race 122 of the thrust bearing 107 abuts. For example, as shown in FIG. 3, the plurality of oil holes 131 are arranged at equiangular intervals around the rotation axis C. Each oil hole 131 penetrates the pressing portion 113 in the thickness direction. At the end of each oil hole 131 on the space 125 side (race 122 side), as shown in FIG. The oil retention part 132 in which is retained is formed.

<Effect>

  An oil hole 131 is formed in the piston 105. Therefore, when the reverse clutch C1 is engaged (when the clutch plates 103 and 104 are pressed by the piston 105), the hydraulic pressure supplied to the hydraulic chamber 106 causes a hydraulic pressure between the piston 105 and the race 122 of the thrust bearing 107. The hydraulic oil supplied to the chamber 106 is supplied through the oil hole 131. Thereby, the space between the piston 105 and the race 122 can be sufficiently lubricated with the hydraulic oil as the lubricating oil. Therefore, even if the race 122 hits the piston 105 and a rotational force (relative rotational force) is generated between the race 122 and the piston 105, the contact portion between the race 122 and the piston 105 is worn. This can be suppressed.

  In addition, when hydraulic oil is first supplied to the hydraulic chamber 106, air usually remains in the hydraulic chamber 106 and an air pocket is generated in the upper portion of the hydraulic chamber 106. Since the oil hole 131 is formed in the piston 105, the air in the hydraulic chamber 106 can escape to the space on the clutch plates 103 and 104 side with respect to the piston 105 through the oil hole 131. Therefore, the hydraulic chamber 106 can be filled with hydraulic oil, and the hydraulic pressure can be applied to the entire piston 105. As a result, when the reverse clutch C1 is engaged, the piston 105 can be prevented from being inclined with respect to the rotation axis direction, and the clutch plates 103 and 104 can be favorably pressed by the piston 105.

  Furthermore, since oil can be circulated between the hydraulic chamber 106 and the space 125 on the clutch plates 103 and 104 side, it is possible to prevent the same oil from staying in the hydraulic chamber 106.

  Further, since the race 122 abuts against the piston 105 and the oil hole 131 is closed by the race 122, it is possible to suppress the hydraulic oil in the hydraulic chamber 106 from being excessively removed from the oil hole 131. As a result, the hydraulic pressure (engagement pressure) required for pressing the plurality of clutch plates 103 and 104 by the piston 105 can be stably secured.

  An oil retaining portion 132 is formed at the end of the oil hole 131 on the space 125 side. As a result, the oil can be retained in the oil retaining portion 132, so that the oil can be supplied more favorably between the piston 105 and the race 122.

  A plurality of oil holes 131 are formed at equiangular intervals around the rotation axis C. By forming the plurality of oil holes 131, oil can be supplied uniformly between the piston 105 and the race 122 in the circumferential direction. Furthermore, by arranging the plurality of oil holes 131 at equal angular intervals around the rotation axis C, oil can be supplied more evenly between the piston 105 and the race 122 in the circumferential direction.

<Modification>

  As mentioned above, although one Embodiment of this invention was described, this invention can also be implemented with another form.

  For example, as indicated by a two-dot chain line (virtual line) in FIG. 3, an oil groove 133 extending in the circumferential direction so as to connect the oil retaining portion 132 of each oil hole 131 to the surface of the piston 105 on the space 125 side. May be formed. By forming the oil groove 133, oil can be supplied to the thrust bearing 107 more evenly in the circumferential direction.

  Furthermore, an oil groove extending in the radial direction from each oil hole 131 may be formed on the surface of the piston 105 on the space 125 side. In the configuration in which the radial oil groove is formed, part of the hydraulic oil supplied from the oil hole 131 to the space 125 side flows out between the piston 105 and the race 122 through the radial oil groove. Thereby, hydraulic fluid can be supplied to various members disposed in the space 125 as lubricating oil.

  Moreover, although the case where this invention was applied to the reverse clutch C1 of CVT4 was taken as an example, this invention can also be applied to the forward brake B1 of CVT4. Of course, the present invention is not limited to CVT4, and the present invention is incorporated in other types of transmissions such as AT (Automatic Transmission), DCT (Dual Clutch Transmission), MT (Manual Transmission), etc. It can also be applied to other clutches (brakes). Further, the present invention may be applied to a clutch (brake) incorporated in a mechanism other than the transmission.

  In addition, various design changes can be made to the above-described configuration within the scope of the matters described in the claims.

103 Clutch plate 104 Clutch plate 105 Piston 106 Hydraulic chamber 107 Thrust bearing 131 Oil hole C Rotating axis C1 Reverse clutch

Claims (1)

A plurality of clutch plates arranged side by side in the rotational axis direction;
A thrust bearing disposed on one side of the rotational axis direction with respect to the plurality of clutch plates;
A piston that is provided so as to be movable in the rotational axis direction, and that applies a load to the plurality of clutch plates from the one side via the thrust bearing;
A hydraulic chamber formed on the one side with respect to the piston and supplied with hydraulic pressure acting on the piston;
The wet multi-plate clutch, wherein an oil hole penetrating the piston in the rotational axis direction is formed in the piston at a position facing the thrust bearing in the rotational axis direction.

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