阅读说明：本技术 具有断开式离合器的变矩器组件 (Torque converter assembly with disconnect clutch ) 是由 肯尼斯·亨特 于 2020-03-23 设计创作，主要内容包括：一种变矩器组件,包括能够连接至动力装置的输入板、变矩器以及断开式离合器,该断开式离合器在变矩器的外部并且构造成将输入板选择性地联接至变矩器。变矩器包括覆盖件,该覆盖件具有外表面和延伸穿过覆盖件的至少一个流体孔。断开式离合器由加压流体经由流体孔致动。(A torque converter assembly includes an input plate connectable to a power plant, a torque converter, and a disconnect clutch external to the torque converter and configured to selectively couple the input plate to the torque converter. The torque converter includes a cover having an outer surface and at least one fluid aperture extending through the cover. The disconnect clutch is actuated by pressurized fluid via a fluid orifice.)

1. A torque converter assembly, comprising:

an input plate connectable to a power plant;

a torque converter including a cover having an outer surface and at least one fluid aperture extending through the cover; and

a disconnect clutch external to the torque converter and configured to selectively couple the input plate to the cover, wherein the disconnect clutch is configured to actuate via the fluid aperture in response to pressurized fluid.

2. The torque converter assembly of claim 1 further comprising an axially movable piston adjacent the outer surface of the cover to be acted upon by the pressurized fluid, wherein axial movement of the piston by the pressurized fluid actuates the disconnect clutch.

3. The torque converter assembly of claim 2 wherein said piston defines an inner peripheral surface and said outer surface of said cover defines a seat supporting said inner peripheral surface of said piston thereon.

4. The torque converter assembly of claim 2 further comprising a piston seal ring surrounding the piston, wherein the piston seal ring, the piston, and the cover cooperate to define a piston chamber of the disconnect clutch.

5. The torque converter assembly of claim 2 further comprising a resilient member disposed between the piston and the disconnect clutch and biasing the piston away from the disconnect clutch.

6. The torque converter assembly of claim 1, wherein the at least one fluid aperture is a plurality of fluid apertures arranged circumferentially around the cover.

7. The torque converter assembly of claim 1 wherein the disconnect clutch is a sprag clutch.

8. The torque converter assembly of claim 7 wherein the sprag clutch includes an inner race connected to the input plate, an outer race connected to the outer surface of the cover, and sprag elements disposed radially between the inner race and the outer race.

9. The torque converter assembly of claim 1, wherein the torque converter further includes an impeller, a turbine, and a bypass clutch configured to mechanically couple the cover to the turbine, the bypass clutch having an internal piston controlled according to fluid pressure within the cover.

10. The torque converter assembly of claim 9 wherein the inner piston defines at least one fluid opening aligned with the at least one fluid bore.

Technical Field

The present disclosure relates to a torque converter assembly having a disconnect clutch selectively coupling the torque converter to a power plant.

Background

Some hybrid vehicles include an engine, a motor/generator (M/G), and an automatic transmission arranged in series. The automatic transmission may include a torque converter for coupling the transmission input shaft to a crankshaft of the engine. The torque converter may include an impeller fixed to the crankshaft, a turbine fixed to the input shaft, and a stator disposed between the impeller and the turbine. The torque converter may also include a bypass clutch to mechanically couple the transmission input shaft to a housing of the torque converter, the housing being fixed to the crankshaft. The bypass clutch may include one or more clutch plates that rotate with the housing and interleave with one or more discs that rotate with the input shaft. To engage the clutch, pressurized fluid forces a piston to compress the plates and discs.

Disconnect clutches may be used to couple and decouple the engine to the M/G, the torque converter, or both, depending on the design. The disconnect clutch is used to decouple the engine from the powertrain in the electric mode.

Disclosure of Invention

According to one embodiment, a torque converter assembly includes an input plate connectable to a power plant, a torque converter, and a disconnect clutch external to the torque converter and configured to selectively couple the input plate to the torque converter. The torque converter includes a cover having an outer surface and at least one fluid aperture extending through the cover. The disconnect clutch is actuated by pressurized fluid via a fluid orifice.

According to another embodiment, a torque converter assembly includes an input plate connectable to a power plant and a torque converter having a cover having an outer surface and at least one fluid aperture extending through the cover. The disconnect clutch of the assembly selectively couples the input plate to the torque converter. The disconnect clutch includes a first member fixedly coupled to the input plate, a second member fixedly coupled to the cover, and a piston adjacent an outer surface of the cover to be acted upon by fluid within a fluid power chamber of the torque converter via a fluid aperture. The piston is axially movable between a first position corresponding to the disconnect clutch being engaged and a second position corresponding to the disconnect clutch being disengaged, depending on the pressure of the fluid.

According to yet another embodiment, a torque converter assembly includes an input plate, a torque converter having a cover defining a fluid power chamber, a bypass clutch disposed within the fluid power chamber, and a disconnect clutch configured to selectively couple the input plate to the cover. The disconnect clutch is located outside of the hydrodynamic chamber and has an outer piston seated on an outer surface of the cover that is axially movable and in fluid communication with the hydrodynamic chamber.

Drawings

FIG. 1 is a side cross-sectional view of a torque converter assembly having a disconnect clutch and a torque converter in a combined assembly.

FIG. 2 is a partially exploded view of the torque converter assembly.

FIG. 3A is an axial cross-sectional view of the exemplary disconnect clutch in the locked position.

Fig. 3B is an axial cross-section of the disconnect clutch in the unlocked position.

Fig. 4A is a top cross-sectional view of the disconnect clutch in the locked position.

Fig. 4B is a top cross-sectional view of the disconnect clutch in the unlocked position.

Detailed Description

Embodiments of the present disclosure are described herein. However, it is to be understood that the disclosed embodiments are merely examples and that other embodiments may take various alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the embodiments. Those of ordinary skill in the art will appreciate that various features illustrated and described with reference to any one of the figures may be combined with features illustrated in one or more other figures to produce embodiments that are not explicitly illustrated or described. The combination of features shown provides a representative implementation for typical applications. However, various combinations and modifications of these features consistent with the teachings of the present disclosure may be desired for particular applications or implementations.

The present disclosure sets forth a combined disconnect clutch and torque converter, referred to herein as a torque converter assembly, for use with, for example, a hybrid vehicle. The torque converter assembly is configured to receive input torque from the engine and/or the at least one electric machine and output the torque to an input shaft of the transmission. The torque converter assembly may replace a separate disconnect clutch and torque converter assembly to form a more compact powertrain set.

Referring to fig. 1 and 2, the torque converter assembly 20 includes a first input 22 and a second input 24. The first input 22 is configured to be fixedly coupled to an engine (not shown). The first input 22 may be an annular plate that is connected to a flexplate 26 (also referred to as a flywheel) of the engine via a damper 28. The second input 24 is configured to be fixedly coupled to a motor (not shown). The second input 24 may be a ring gear, spur gear, sprocket, pulley, or any other device capable of being drivably connected to a motor.

The torque converter assembly 20 includes a torque converter 21 having a cover 30 that receives power from the first input 22, the second input 24, or both. The cover 30 may receive power through a fixed coupling (e.g., direct connection) or a selective coupling (e.g., clutch). A set of rotating elements is fixedly coupled to each other if the set of rotating elements is constrained to rotate as a unit under all operating conditions. The rotating elements may be fixedly coupled by spline connection, welding, press fitting, machining from the same solid, dampers, or other means. Minor variations in rotational displacement between fixedly coupled elements may occur, such as displacement due to shock, shaft compliance or damper vibration. Conversely, two rotating elements are selectively coupled by a clutch or other device described above when the two rotating elements are restricted from rotating as a unit whenever the clutch or other device is fully engaged and are free to rotate at different, unrelated speeds under at least some other operating conditions. Two elements are coupled if they are fixedly coupled or selectively coupled.

The torque converter assembly 20 also includes a disconnect clutch 32. Disconnect clutch 32 may selectively couple input 22 to cover 30. The second input 24 may be fixedly coupled to the cover 30. The cover 30 may include a front cover 34 and a rear cover 35 that are joined to one another, such as by welding or the like. The impeller 36 is fixed to the rear cover 35 and rotates with the cover 30. The turbine 38 is disposed adjacent to the impeller 36 within a fluid power chamber 40 of the torque converter 21. The turbine 38 is coupled to a turbine hub 42 that is connected, e.g., splined, to a transmission input shaft (not shown) that powers a gearbox of the transmission. The impeller 36 and turbine 38 are designed to be fluidly coupled, thereby forming a hydrodynamic power flow path.

The stator 44 is supported on a stator shaft (not shown) by a one-way clutch 46. The stator shaft is fixed to the front support of the transmission and is stationary relative to the torque converter assembly 20. The one-way clutch 46 holds the stator 44 stationary when the transmission input shaft is stationary or rotating slowly compared to the crankshaft. The rotation of the impeller 36 forces the fluid to move between the impeller 36, the turbine 38, and the stator 44. The fluid exerts a hydrodynamic torque on the turbine 38. The stator 44 provides a reaction force such that the torque on the turbine 38 is greater than the torque on the impeller 36. As the speed of the turbine 38 approaches the speed of the impeller 36, fluid tends to flow about the centerline of the torque converter, causing the one-way clutch 46 to overrun.

The torque converter 21 may include a bypass clutch 50 that mechanically connects the turbine 38 to the cover 30 to bypass the hydrodynamic power flow path of the torque converter 21. The bypass clutch 50 is often engaged during cruise to improve fuel efficiency. The bypass clutch 50 may include a clutch disc 52 operated by a clutch piston (internal piston) 54. The piston 54 may be an annular plate. The clutch disc 52 may include at least one friction material 56 disposed thereon. The clutch disc 52 is disposed between the clutch piston 54 and the inner surface 58 of the front cover 34. The clutch 50 is engaged by moving the clutch piston 54 toward the front cover 34 to frictionally lock the clutch disc 52 to the cover 30. The turbine 38 is secured to the clutch disc 52 by a damper 60. Thus, when the bypass clutch 50 is fully engaged to bypass the hydrodynamic power flow path and instead mechanically couple the engine or the electric machine to the transmission, the turbine 38 is fixed to the cover 30. Other bypass clutch designs may be used in the torque converter assembly 20. The clutch piston 54 of the illustrated embodiment may be hydraulically actuated by supplying a fluid, such as oil, to the fluid power chamber 40. Other types of bypass clutches may include a dedicated fluid chamber for urging the clutch piston, in which case fluid is supplied to the dedicated fluid chamber to engage the clutch.

A disconnect clutch 32 selectively couples the input 22 to the cover 30. When the disconnect clutch 32 is engaged (closed or locked), the engine is coupled to the motor and transmission, and when the clutch 32 is disengaged (open or unlocked), the engine is isolated from the motor and transmission. Disconnect clutch 32 selectively couples first input 22 to front cover 34 so that cover 30 rotates generally in unison with the crankshaft of the engine.

The disconnect clutch 32 may include a first member fixedly coupled to the input 22 and a second member fixedly coupled to the cover 30. The first member may be directly connected to the input 22 by welding or other attachment means, while the second member may be directly connected to the cover 30 by welding or other attachment means. The disconnect clutch 32 includes a clutch mechanism configured to fix the first and second members when the clutch is engaged, and to allow relative rotation between the first and second members when the clutch 32 is disengaged. Disconnect clutch 32 may be any type of clutch capable of engaging and disengaging the engine from torque converter 21. An exemplary clutch includes: sprag clutches, roller clutches, dry friction clutches and wet friction clutches (both single disc and clutch pack variants).

The disconnect clutch 32 may be actuated by an external piston 150. The outer piston 150 may be a piston ring having an outer peripheral surface 152 and an inner peripheral surface 154. The external piston 150 may be located adjacent to the front cover 34 and between the disconnect clutch 32 and the torque converter 21. The outer piston 150 may be axially movable relative to the disconnect clutch 32. For example, the inner surface 154 may be slidably received on a seat 156 defined by an outer surface 158 of the front cover 34. In one or more embodiments, movement of the piston 150 toward the disconnect clutch 32 to the first position disengages the disconnect clutch, while movement toward the torque converter 21 to the second position allows the disconnect clutch 32 to be reengaged (where the disconnect clutch is biased to lock). A resilient member 170, such as a return spring, may bias the piston 150 to the second position.

The seal ring 160 may circumscribe the outer piston 150 and the seat 156. Seal ring 160 includes an axially extending surface 162 adjacent outer surface 152 and a radially extending surface 164 fixedly coupled, e.g., directly connected, to front cover 34. A seal 166 may be disposed between the seat 156 and the piston 150, and the seal 166 may be disposed between the axially extending surface 162 and the piston 150. The seat 156 and the sealing ring 160 cooperate to define an annular cavity in which the piston 150 is slidably received.

The external piston 150 may be hydraulically actuated. The external piston 150 may be in fluid communication with the hydrodynamic chamber 40 and controlled by providing fluid pressure into the hydrodynamic chamber 40. The front cover 34 may define one or more fluid apertures 172 extending completely through a wall 173 of the front cover 34, allowing fluid to flow from the torque converter 21 and contact a backside 184 of the outer piston 150. In the illustrated embodiment, front cover 34 defines a plurality of fluid apertures 172 arranged circumferentially about wall 173. Front cover 34 may include one or more bosses 176, each extending from inner surface 58 and defining a corresponding aperture 172. The diameter of the outer piston 150 and the diameter of the array of fluid holes 172 are similar such that fluid exiting the holes 172 contacts the backside 184 of the piston 150. The sealing ring 160, the piston 150, and the front cover 34 cooperate to define a fluid chamber 180 for urging the piston 150. The seal 166 prevents fluid from leaking from the chamber 180.

The inner piston 54 of the bypass clutch 50 may define a plurality of openings 182 having a diameter greater than the boss 176 such that the boss 176 may be received therein. A plurality of seals 186 may be disposed between the opening 182 and the boss 176. The opening 182 provides a pathway for fluid to flow from the hydrodynamic chamber 40 to the at least one fluid chamber 180.

Disconnect clutch 32 may be disengaged by providing fluid to fluid power chamber 40 such that the fluid pressure within chamber 40 exceeds a first threshold sufficient to overcome the bias of resilient member 170. The disconnect clutch 32 may be reengaged by reducing the fluid pressure within the fluid power chamber 40 such that the resilient member 170 returns the outer piston 150 to the second position. As described above, the bypass clutch 50 is also actuated in response to the fluid pressure within the fluid power chamber 40. That is, both the bypass clutch 50 and the disconnect clutch 32 are controlled by the same fluid chamber. To allow the two clutches to be separately actuated, the outer piston 150 of the disconnect clutch 32 is designed to be pushed in response to the fluid pressure exceeding a first threshold value, while the inner piston 54 of the bypass clutch 50 is designed to be pushed in response to the fluid pressure exceeding a second threshold value, which is less than the first threshold value. Alternatively, in other embodiments, it may be desirable for the outer piston 150 to actuate with the inner piston 54 such that the first threshold is equal to the second threshold. In other embodiments, each of the clutches 32 and 50 may have a dedicated fluid circuit to allow the clutches to operate completely independently, rather than only one of the clutches operating independently.

The design of the outer piston 150, the magnitude of the first threshold, and the strength of the resilient member 170 (and whether the resilient member is present or not) may depend on the design of the disconnect clutch, including type, size, clutch capacity, and the like. In the embodiment shown, the disconnect clutch 32 is a sprag clutch. The sprag clutch locks via a wedging action within the clutch and does not rely on the outer piston 150 to generate the clutch capacity. In fact, some sprag clutches are biased into engagement, in which case the piston 150 is used to disengage the clutch rather than apply the clutch. In other clutch types, such as wet friction clutches, the piston 150 is used to generate clutch capacity. Thus, the fluid circuit for the outer piston 150 may vary.

A sprag clutch may include an inner race 70, an outer race 72, and sprag elements 74 disposed radially between the inner race 70 and the outer race 72. The inner and outer races may be concentric. The wedge elements 74 may be a disc, a plurality of axially stacked discs, or a cylinder. Sprag elements 74 are configured to lock inner race 70 and outer race 72 when clutch 32 is engaged, and to allow relative rotation between inner race 70 and outer race 72 when the clutch is disengaged. Inner race 70 may be fixedly coupled to input 22 and outer race 72 may be fixedly coupled to cover 30. The inner race 70 and the outer race 72 may be fixedly coupled to their respective components by welding, fasteners, or the like. In an alternative embodiment, the inner race 70 may be fixedly coupled to the cover 30 and the outer race 72 may be fixedly coupled to the input 22. The inner race 70 may be annular and seats on a guide hub 76 of the cover 30. Bearings 80, such as roller bearings, or other anti-friction mechanisms may be disposed between the inner peripheral surface 78 of the inner race 70 and the guide hub 76. The outer race 72 may be fixedly coupled to the cover 30 by an interconnecting plate 82. The interconnect plate 82 may include a first end attached to the outer race 72 and a second end attached to the second input 24, the cover 30, or both. The interconnect board 82 may be attached by welding, fasteners, or the like.

Referring to fig. 1 and 3A, a sprag clutch operates by radially expanding and contracting sprag elements 74 between inner and outer races 70, 72 to disengage and engage the clutch, respectively. The sprag clutch has a cam surface 88 formed on one of the inner race 70 and the outer race 72. The race without the cam surface 88 defines a circular groove 90 configured to frictionally engage the wedge element 74. In the illustrated embodiment, the outer race 72 defines a cam surface 88 on an inner peripheral surface, while the outer surface of the inner race 70 defines a groove 90. In other embodiments, the groove 90 and cam surface 88 may be reversed to become a groove formed on the outer race and a cam surface formed on the inner race.

When the clutch 32 is engaged, friction between the inner edge of the wedge element 74 and the groove 90 rotationally locks the wedge element 74 to the inner race 70. Wedge member 74 includes a cam surface 92 that engages and cooperates with cam surface 88. The cam surfaces 88 define a plurality of ramps configured to engage the lobes of the cam surfaces 92 to wedge the wedge elements 74 between the inner and outer races in response to rotation of the wedge elements 74 and outer race 72 relative to each other. The wedging action caused by the cam surfaces 88, 92 clamps the wedge member 74 tightly to the inner race 70, creating a frictional coupling. The ramps and lobes are sized such that they cannot slide over each other and cooperate to lock wedge element 74 to outer race 72.

Referring to fig. 3A and 3B, wedge element 74 may be formed from a plurality of arcuate segments 100 circumferentially arranged between inner race 70 and outer race 72. The segments 100 are arranged in pairs to form a plurality of arcuate wedge segments 102 of the wedge element 74. Each of the segments 102 includes a first segment 100a and a second segment 100b, which may be mirror images of each other, with pairs of segments arranged with a first end 104 facing each other and a second end 106 facing away from each other. A plurality of resilient members 108, such as coil springs, are circumferentially arranged between the segments 102. The resilient member 108 biases the segments 100a and 100b toward each other and biases the segments 102 away from each other. In the illustrated embodiment, there are ten segments arranged into five segments 102 and ten elastic members 108 (two elastic members disposed between each segment). In other embodiments, a different number of sections, segments, and resilient members may be used.

The thickness of each segment 100 varies between a first end 104 and a second end 106 to form the cam surface 92. The second end 106 is radially thicker than the first end 104 such that the outer surface 112 slopes radially outward from the first end 104 toward the second end 106. The outer surface 112 of each segment 100 defines a portion of the cam surface 92. The aforementioned lobe, indicated at 113, is the outermost portion of the cam surface 92 and is generally formed by the outer surface 112 proximate the second end 106. The inner surface 111 of each segment 100 is a smooth circular arc having a constant radius that substantially matches the outer diameter of the inner race 70.

The cam surface 88 of the outer race 72 has a profile that substantially matches the cam surface 92 of the wedge member 74. The camming surface 88 includes a radially extending ramp 116 and a pocket 118. The mating shapes of cam surfaces 88, 92 allow wedge element 74 to nest within outer race 72 with lobes 113 disposed in cavities 118.

The resilient member 108 biases the sprag elements 74 to a retracted position in which each of the sections 100 is in frictional contact with the inner race 70, creating sufficient resistance to rotation of the sprag elements 74 relative to the outer race 72 in the event that the input 22 receives power. Relative rotation between the outer race 72 and the wedge elements 74 misaligns the cam surfaces 88, 92, i.e., the ramps 116 slide into the lobes 113, causing further radial contraction of the wedge elements 74. This further radial contraction clamps wedge elements 74 to inner race 70 with sufficient frictional force to rotationally lock inner race 70 and outer race 72 to engage clutch 32.

Referring to fig. 2-4B, the disconnect clutch 32 may be disengaged by separating the segments 100a and 100B of each pair to move the wedge elements 74 to the expanded position shown in fig. 3B. The outer piston 150 moves the wedge members 74 between the retracted and expanded positions. The piston 150 may include a plurality of axially extending projections (fingers) 134 extending from the front side and configured to be received in the slots 140 of the segment 102. The fingers 134 are circumferentially arranged about the piston 150. The number of fingers 134 may be equal to the number of segments 102, and in the illustrated embodiment, the piston 150 has five fingers 134.

Each of the slots 140 may be recessed into a corresponding one of the segments 102, with the first segment 100a defining one half of the slot and the second segment 100b defining the other half of the slot. Each slot 140 includes a first portion 142, a second portion 144 narrower than the first portion, and an angled portion 146 transitioning between the first and second portions 142, 144. The fingers 134 may have a shape that substantially matches the shape of the slots 140. Each of the fingers 134 may include a main portion 138 and a tip 141. The main portion 138 is sized to fit closely within the first portion 142, while the tip 141 is sized to fit closely within the second portion 144. The finger 134 also includes an angled side 143 that matches the angled portion 146 of the slot 140.

Axial movement of the piston 150 toward the wedge element 74 disengages the clutch 32 by driving the angled sides 143 into the ramped portions 146 to disengage the segment pairs 100a and 100b of each segment 102, thereby moving the clutch element 74 to the expanded position. The amount of separation can be adjusted by adjusting the width of the fingers 134 and slots 140. The axial force required to separate the segment pairs can be adjusted by changing the slope of the angled side portions 143 and the angled portions 146. Clutch 50 may be reengaged by retracting fingers 134 and allowing resilient member 108 to urge wedge element 74 to rotate relative to outer race 72.

The wedge clutch described above is just one example of a wedge clutch that may be used as a disconnect clutch in the torque converter assembly 20. Other types of sprag clutches may also be suitable. For example, another type of sprag clutch may include a tapered hub having a first cam surface. The wedge element is seated on the tapered hub with the second cam surface of the wedge element engaging the first cam surface. The sprag clutch is engaged by rotating the hub relative to the sprag elements to misalign the cam surfaces. This type of clutch engages and disengages by axially sliding the wedge elements relative to the hub between a larger diameter portion (engagement area) and a smaller diameter portion (disengagement area). An outer piston 54 may be used to slide the wedge elements over the hub, thereby controlling the actuation of the clutch.

While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms encompassed by the claims. The words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the disclosure. As previously mentioned, features of the various embodiments may be combined to form further embodiments of the invention, which may not be explicitly described or illustrated. Although various embodiments may have been described as providing advantages or being preferred over other embodiments or prior art implementations with respect to one or more desired characteristics, those of ordinary skill in the art will recognize that one or more features or characteristics may be compromised to achieve desired overall system attributes, which depend on the particular application and implementation. These attributes may include, but are not limited to, cost, strength, durability, life cycle cost, marketability, appearance, packaging, size, serviceability, weight, manufacturability, ease of assembly, and the like. As such, to the extent that any embodiment is described as less than ideal compared to other embodiments or prior art implementations, such embodiments do not depart from the scope of the present disclosure and may be ideal for a particular application in terms of one or more characteristics.

The following is a list of reference numerals shown in the drawings. However, it should be understood that the use of these terms is for illustrative purposes only for one embodiment. Also, the use of reference numbers associated with certain terms that are presented in both the drawings and the claims is not intended to limit the claims to cover only the illustrated embodiments.

List of parts 20 torque converter assembly 21 first input 24 second input 26 flexible plate 28 damper 30 cover 32 break-away clutch 34 front cover 35 back cover 36 impeller 38 turbine 40 fluid power chamber 42 turbine hub 44 stator 46 one way clutch 50 bypass clutch 52 clutch disc 54 clutch piston 56 friction material 58 inner surface 60 damper 70 inner race 72 outer race 74 clutch element 76 guide hub 78 inner surface 80 bearing 82 interconnecting plate 88 cam surface 90 groove 92 cam surface 100 section 102 first end 106 second end 108 elastic member 111 inner surface 113 116 ramp cam surface 116 groove 118 groove 138 main portion 138 groove 140 groove 138 141 first portion 143 of tip 142 angled side portion 144 second portion 146 inclined portion 150 outer piston 152 outer peripheral surface 154 inner peripheral surface 156 seat 158 outer surface 160 sealing ring 162 axially extending surface 164 sealing ring 170 fluid bore 173 wall 176 boss 180 fluid chamber 184 backside 186 seal.