Pneumatic clutch actuator

A pneumatic clutch actuator includes an actuator housing, a piston assembly, a bearing carrier, and a locking element. The piston assembly is disposed within the actuator housing and is movable between a first position and a second position. The piston assembly has a piston head, an elongate member extending from the piston head, and a lock ring coupled to the elongate member. The bearing carrier supports a bearing and is slidably disposed on a portion of the actuator housing. The locking element is operatively connected to the piston assembly and engages the bearing carrier to adjust a total length of the piston assembly as the piston assembly moves from the second position towards the first position to compensate for wear of the clutch assembly.

TECHNICAL FIELD

The present disclosure relates to an automatically adjustable pneumatic clutch actuator.

BACKGROUND ART

Motor vehicles are commonly provided with a clutch actuator that is connected to a clutch assembly. The clutch assembly is configured to selectively separate frictionally coupled elements and to transfer energy from a power source, such as an engine output shaft, to a transmission input shaft. The clutch assembly is configured to move between an engaged state and a disengaged state. The clutch assembly includes a clutch disc having a friction surface. The clutch disc friction surface engages a flywheel that is operatively connected to the engine output shaft. The engine output shaft is operatively coupled to the transmission input shaft while the clutch assembly is in the engaged state. The clutch disc friction surface may be disengaged from the flywheel such that the engine output shaft is operatively decoupled from the transmission input shaft.

The selective engagement and disengagement of the clutch assembly may be accomplished by a clutch actuator. The clutch actuator moves the clutch disc friction surface between engagement and disengagement with the flywheel. Over time, the clutch disc friction surface wears and becomes thinner leading to an increased distance of travel for the clutch disc friction surface to the flywheel.

SUMMARY

According to an exemplary embodiment of the present disclosure, a pneumatic clutch actuator provided with a clutch assembly is provided. The pneumatic clutch actuator includes an actuator housing, a piston assembly, a bearing carrier, and a locking element. The piston assembly is disposed within the actuator housing and is movable between a first position and a second position. The piston assembly is configured to selectively change a clutch state between an engaged state and a disengaged state. The piston assembly has a piston head, an elongate member extending from the piston head, and a lock ring coupled to the elongate member. The bearing carrier supports a bearing and is slidably disposed on a portion of the actuator housing. The locking element is operatively connected to the piston assembly and engages the bearing carrier to adjust a total length of the piston assembly as the piston assembly moves from the second position towards the first position to compensate for wear of the clutch assembly.

According to another exemplary embodiment of the present disclosure, a pneumatic clutch actuator is provided. The pneumatic clutch actuator includes a housing assembly, a bearing assembly, a piston assembly, and an adjustment assembly. The housing assembly is provided with a first housing member and a second housing member. The first housing member has an inner annulus disposed about a transmission input shaft and is at least partially received within the second housing member. The bearing assembly is at least partially received within the housing assembly and is disposed about the inner annulus. The bearing assembly has a bearing carrier that supports a bearing. The piston assembly has a piston head and an extension extending from the piston head towards the bearing assembly. The adjustment assembly is disposed between and is operatively connected to the bearing carrier and the piston head. The adjustment assembly is arranged to adjust a distance between the piston assembly and the bearing assembly as the piston assembly moves between a first position and a second position to compensate for wear of a clutch assembly.

According to yet another exemplary embodiment of the present disclosure, a pneumatic clutch actuator is provided. The pneumatic clutch actuator includes a housing disposed about a shaft, a cover, a bearing assembly, a piston assembly, and an adjustment assembly. The cover is disposed about the shaft and the housing and is movable relative to the housing. The bearing assembly is disposed on the cover and is arranged to selectively engage a clutch assembly. The piston assembly is disposed within the housing and is movable between a first position and a second position to selectively change a state of the clutch assembly between an engaged state and a disengaged state. The adjustment assembly is disposed between the cover and the piston. The adjustment assembly is arranged to adjust a distance between the piston and the bearing assembly to compensate for wear of the clutch assembly.

According to still yet another exemplary embodiment of the present disclosure, a pneumatic clutch actuator is provided. The pneumatic clutch actuator includes a housing assembly, a bearing assembly, a piston assembly, and an adjustment assembly. The housing assembly has a first housing member and a second housing member that at least partially receives the first housing member. The first housing member is provided with an inner annulus that is disposed about a transmission input shaft. The bearing assembly is disposed on a portion of the housing assembly and has a bearing carrier that supports a bearing. The piston assembly is slidably disposed within the housing assembly and is movable between a first position and a second position to selectively change a clutch assembly between an engaged state and a disengaged state. The adjustment assembly is disposed between the bearing assembly and the piston assembly. The adjustment assembly is configured to adjust a total length of the piston assembly to compensate for wear of the clutch assembly.

The above features and advantages and other features and advantages of the present disclosure are readily apparent from the following detailed description of the present disclosure when taken in connection with the accompanying drawings.

DESCRIPTION OF EMBODIMENTS

Referring toFIGS. 1A and 1B, vehicles are commonly provided with a clutch assembly1to selectively couple rotating components to transmit torque to another rotatable component. The clutch assembly1includes a clutch2that selectively engages a flywheel3to selectively couple and decouple the rotating components. The clutch2includes a clutch disc4that rotates with the transmission input shaft5and is configured to slide axially along the transmission input shaft5. A friction surface4A of the clutch disc4is pressed by a diaphragm spring6through a pressure plate7against a face of the flywheel3.

The diaphragm spring6is pivotally mounted to a clutch cover8that receives the clutch2, the diaphragm spring6, the pressure plate7, as well as other components. The diaphragm spring6is arranged such that an axial force that is provided via a thrust bearing9moves the pressure plate7towards the clutch disc4to engage the friction surface4A. The diaphragm spring6is arranged such that an axial force that is applied via a pneumatic clutch actuator10as the pneumatic clutch actuator10moves from a first position towards a second position. As the pneumatic clutch actuator moves towards the second position to disengage the clutch assembly1, as shown inFIG. 1B.

A first exemplary embodiment of a pneumatic clutch actuator10is illustrated inFIGS. 2-4. A second exemplary embodiment of the pneumatic clutch actuator10is illustrated inFIGS. 5-9. A third exemplary embodiment of a pneumatic clutch actuator10is illustrated inFIGS. 10-12. A fourth exemplary embodiment of a pneumatic clutch actuator10is illustrated inFIGS. 13-18.

A partial cross-sectional view of the pneumatic clutch actuator10is shown inFIG. 2. The pneumatic clutch actuator10is configured to selectively change the state of the clutch assembly1between an engaged state and a disengaged state.

The pneumatic clutch actuator10includes an actuator housing20, a piston assembly22, a bearing assembly24, a locking element26, and a release ring28.

The actuator housing20is disposed about the transmission input shaft5(FIGS. 1A and 1Band is configured as an annular housing. The actuator housing20includes a floor40, a first annular wall42, and a second annular wall44.

The floor40includes a first end46that is spaced apart from the transmission input shaft5and a second end48that is disposed proximate the transmission input shaft5. The first annular wall42extends from the first end46of the floor40and is disposed substantially perpendicular to the floor40. The first annular wall42is disposed substantially parallel to the transmission input shaft5and includes a first annular wall inner surface50and a first annular wall outer surface52.

The second annular wall44is spaced apart from the first annular wall42. The second annular wall44extends from the second end48of the floor40and is disposed substantially perpendicular to the floor40. The second annular wall44is disposed substantially parallel to the transmission input shaft5and includes a second annular wall inner surface54and a second annular wall outer surface56. The second annular wall outer surface56defines a bore within which the transmission input shaft5is received.

The floor40, the first annular wall inner surface50, and the second annular wall inner surface54define a cavity58within which the piston assembly22is received. The piston assembly22is slidably or movably disposed within the cavity58. The piston assembly22is configured to selectively change a state of the clutch2of the clutch assembly1between the engaged state and the disengaged state. The piston assembly22is movable between a first position and a second position. The first position may correspond to the engaged state of the clutch2. The second position may correspond to the disengaged state of the clutch2.

The piston assembly22includes a piston head70, an elongate member72, and a lock ring74. The piston head70is configured as a generally cylindrical body and may be disposed adjacent to the floor40when the piston assembly22is in the first position. Compressed air is provided to the pneumatic clutch actuator10to move the piston assembly22from the first position (adjacent to the floor40) towards the second position. A bottom surface60of the piston head70is spaced apart from the floor40when the piston assembly22is in the second position. The bottom surface60of the piston head70, the floor40, the first annular wall42, and the second annular wall44define a volume62that receives the compressed air. The evacuation or releasing of the compressed air from the volume62enables the piston assembly22to move from the second position towards the first position (adjacent to the floor40as illustrated inFIG. 2.

The piston head70is provided with a circumferential groove76that is configured to receive a sealing member78. The sealing member78is configured to engage the first annular wall inner surface50to prevent or inhibit leakage of the compressed air around the piston head70.

The piston head70defines a mounting member80and an extension member82. The mounting member80extends from the piston head70towards the release ring28. The mounting member80is disposed substantially parallel to the first annular wall42, the second annular wall44, and the transmission input shaft5. The mounting member80has a mounting member height, H, that is measured from a bottom surface60of the piston head70to a portion of the mounting member80. The mounting member80is spaced apart from the first annular wall inner surface50and the second annular wall inner surface54.

The extension member82extends from the piston head70and is disposed substantially parallel to the first annular wall42and the second annular wall44. The extension member82defines at least one circumferential groove84that is configured to receive a sealing member86that is configured to engage the second annular wall inner surface54. The extension member82has an extension member height, h, that is measured from the bottom surface60of the piston head70to an end88of the extension member82. The extension member height, h, is greater than the mounting member height, H.

The extension member82is spaced apart from the mounting member80to define a first spring seat85.

The elongate member72extends from the piston head70and through the release ring28. Specifically, the elongate member72is coupled to the piston head70by the mounting member80, such that the elongate member72extends from the mounting member80. In at least one embodiment, the elongate member72is threaded to or joined with the piston head70. In at least one embodiment, the elongate member72is integrally formed with the piston head70. The elongate member72is disposed proximate the second annular wall44and is in spaced relationship to the second annular wall inner surface54.

The elongate member72defines at least one slot94. The at least one slot94extends at least partially through the elongate member72between the piston head70and an end96of the elongate member72.

The locking ring74is disposed about the transmission input shaft5. The lock ring74is disposed at the end96of the elongate member72that is disposed opposite the piston head70. In at least one embodiment, the lock ring74is configured to move relative to the end96of the elongate member72to change a total length of the piston assembly22.

The lock ring74includes a first lock ring portion100and a second lock ring portion102. The first lock ring portion100extends from the end96of the elongate member72. The first lock ring portion100is disposed substantially parallel to and in sliding contact with the elongate member72. The second lock ring portion102extends from the first lock ring portion100in a substantially perpendicular orientation to the first lock ring portion100. The second lock ring portion102is disposed substantially perpendicular to the elongate member72and extends towards the second annular wall44. The second lock ring portion102is spaced apart from the second annular wall inner surface54.

The elongate member72and the lock ring74define a groove104that is defined by the second lock ring portion102and the end96of the elongate member72.

The bearing assembly24includes a bearing carrier110that supports the bearing9. The bearing carrier110is disposed about the transmission input shaft5. The bearing carrier110is slidably disposed about the second annular wall inner surface54. The bearing carrier110is configured to slide along the second annular wall inner surface54in response to movement of the piston assembly22between the first position and the second position.

The bearing carrier110includes a first bearing carrier portion112and a second bearing carrier portion114. The first bearing carrier portion112is disposed between the second annular wall44and the elongate member72of the piston assembly22. The first bearing carrier portion112is disposed substantially parallel to the second annular wall44and the elongate member72of the piston assembly22. The first bearing carrier portion112includes at least one circumferential groove113that is configured to receive a sealing member115. The sealing member115is configured to engage the second annular wall inner surface54to prevent or inhibit leakage of compressed air.

The first bearing carrier portion112defines a second spring seat116that is opposed to the first spring seat85. A spring or biasing member117extends between the first spring seat85and the second spring seat116and applies a preload to at least one of the piston assembly22and the bearing carrier110.

The second bearing carrier portion114is configured as a curvilinear member that extends from the first bearing carrier portion112away from the second annular wall44towards the elongate member72of the piston assembly22.

A portion of the clutch2of the clutch assembly1, such as the diaphragm spring6, is configured to engage the bearing9. The diaphragm spring6operates to engage and/or disengage the clutch2in response to operation of the pneumatic clutch actuator10through the movement of the piston assembly22between the first position and the second position. The clutch disc4of the clutch2includes a friction surface that may wear during operation of the pneumatic clutch actuator10. As the friction surface of the clutch disc4of the clutch2wears, the piston assembly22may travel a greater distance to move between the first position and the second position. For example, when the piston assembly22moves from the second position towards the first position, the piston head70of the piston assembly22may be spaced apart from the floor40when in the first position due to the wearing of the friction surface of the clutch disc4of the clutch2.

The spacing apart of the piston head70of the piston assembly22from the floor when in the first position presents a dead volume within the volume62that receives the compressed air and is defined between the bottom surface of the piston head70, the floor40, the first annular wall42, and the second annular wall44. The dead volume within the volume62may cause a pneumatic system to supply additional compressed air to move the piston assembly22from the first position towards the second position resulting in a decreased system response time and a decreased system performance. In an attempt to overcome these disadvantages, the locking element26and the release ring28are provided as part of an adjustment mechanism to adjust a total length of the piston assembly22to compensate for wear of the friction surface of the clutch disc4of the clutch2to minimize the dead volume.

Referring toFIGS. 2 and 3, the locking element26is configured as a toothed ring that is disposed between the piston assembly22and the bearing carrier110of the bearing assembly24. The locking element26extends between the locking ring74and the bearing carrier110and is secured between by a retaining element118, such as an O-ring.

The locking element26includes a locking element body120having a first locking element end122and a second locking element end124. The locking element26comprises a ring made of individual bodies each having inner and outer ends. The locking element26includes a plurality of locking element bodies and portions of the locking element body120are curved and touch adjacent portions of the of an adjacent locking element body, as shown inFIG. 4.

The first locking element end122are each received within the groove104that is defined by the second lock ring portion102, the first lock ring portion100, and the end96of the elongate member72. The second locking element end124slidingly engage the bearing carrier110. The locking element bodies120may be arranged as shaped fingers. The shaped fingers may have an elongate shape, a linear shape, a kidney shape, an ovate shape, a reniform shape, a dual reniform shape, an acicular shape, a subulate shape, or the like. For example, as shown inFIG. 3, the first locking element end122has a first width, the second locking element end124has a second width, a portion of the locking element bodies120have a third width that is less than the first width and the second width.

The release ring28is connected to the actuator housing20and may be configured as a cover of the actuator housing20. The release ring28is connected to the first annular wall42of the actuator housing20and extends radially inwardly towards the second annular wall44of the actuator housing20. The release ring28is spaced apart from the second annular wall44of the actuator housing20and extends at least partially through the at least one slot94of the elongate member72of the piston assembly22.

The release ring28includes a raised annulus or collar130that extends from an end132of the release ring28that is disposed proximate the second annular wall44of the actuator housing20. The raised annulus or collar130is disposed generally parallel to the transmission input shaft5and is disposed generally parallel to the second annular wall44. The raised annulus or collar130is configured to selectively engage the locking element26to adjust a total length of the piston assembly22in response to movement of the piston assembly22relative to the release ring28.

The raised annulus or collar130is configured to engage the second locking element end124of the locking element26when the piston assembly22moves from the second position towards the first position. The raised annulus or collar130is configured to engage the second locking element end124when the piston assembly22is in the first position. The raised annulus or collar130pivots or deflects the locking element26about a pivot point or deflection point defined by the retaining element118to lift the second locking element end124off of the first bearing carrier portion112to enable the lock ring74to move longitudinally relative to the elongate member72to adjust a total length of the piston assembly22to compensate for wear of the clutch assembly. The raised annulus or collar130is configured to be spaced apart from the second locking element end124when the piston assembly22moves from the first position towards the second position and when the piston assembly22is in the second position.

In accordance with a second exemplary embodiment, a pneumatic clutch actuator10is illustrated inFIGS. 5-9.

A partial cross-sectional view of the pneumatic clutch actuator10is shown inFIG. 5. The pneumatic clutch actuator10is configured to selectively change the state of the clutch2of the clutch assembly1that is operatively connected to the pneumatic clutch actuator10between an engaged state and a disengaged state (SeeFIGS. 1A and 1B).

The pneumatic clutch actuator10includes a housing assembly160, a bearing assembly162, a piston assembly164, and an adjustment assembly166.

The housing assembly160is circumferentially disposed about the transmission input shaft5and is configured as an annular housing. The housing assembly160includes a first housing member170and a second housing member172. The first housing member170is at least partially received within the second housing member172.

The first housing member170includes a base180, a first annular wall182, and an inner annulus184. The first annular wall182extends from the base180and is disposed substantially perpendicular thereto. The first annular wall182includes an inner surface190and an outer surface192.

The inner annulus184may be a hollow post or annulus that extends axially from the base180and is spaced apart from the first annular wall182. The inner annulus184extends from the base180towards and through the second housing member172inner annulus and is disposed substantially concentric with the first annular wall182and includes an inner annulus inner surface200and an inner annulus outer surface202. The inner annulus inner surface200defines a bore within which the transmission input shaft5is received.

The inner annulus184defines a ramp204that is disposed proximate a terminal end206inner annulus thereof. The ramp204is angled relative to an axis208along which the inner annulus184extends and is defined in the inner annulus outer surface202and extends towards the inner annulus inner surface200.

The second housing member172includes an outer annular wall210, an extension wall212, an inner annular wall214, and a shoulder216extending radially inwardly therefrom. The outer annular wall210includes a second annular wall inner surface220and a second annular wall outer surface222. The second annular wall inner surface220is disposed proximate to and faces towards the outer surface192.

The extension wall212connects the outer annular wall210and the inner annular wall214. The extension wall212is disposed substantially perpendicular to the outer annular wall210and is disposed substantially parallel to the base180. The extension wall212includes an extension wall inner surface230and an extension wall outer surface232.

The inner annular wall214extends from the extension wall212and is disposed substantially perpendicular thereto. The inner annular wall214is disposed substantially parallel to the outer annular wall210and includes a third annular wall inner surface240and a third annular wall outer surface242. The second annular wall inner surface220, the extension wall inner surface230, and the third annular wall inner surface240define an annular cavity244. The annular cavity244is sized to at least partially receive the first annular wall182of the first housing member170.

The shoulder216extends radially inwardly from the inner annular wall214towards the inner annulus184. The shoulder216is disposed substantially perpendicular to the inner annular wall214and is disposed substantially parallel to the extension wall212. The shoulder216includes a first shoulder surface250and a second shoulder surface252. The first shoulder surface250faces away from the base180. The second shoulder surface252faces towards the base180.

The bearing assembly162is at least partially received within the housing assembly160and is disposed about the inner annulus184. The bearing assembly162includes a bearing carrier260and a bearing262.

The bearing carrier260is slidably disposed about the inner annulus outer surface202. The bearing carrier260is slidably disposed about the inner annulus outer surface202. The bearing carrier260slides along the inner annulus outer surface202in response to movement of the piston assembly164or in response to the application of a force or load onto the bearing assembly162by the diaphragm spring6.

The bearing carrier260includes a first bearing carrier portion270and a second bearing carrier portion272. The first bearing carrier portion270is disposed radially between the inner annulus184and the bearing assembly162and extends substantially parallel to the inner annulus184. The first bearing carrier portion270includes a protrusion(s)274that extends radially inwardly towards the axis208of the transmission input shaft5. The protrusion(s)274is configured to engage the ramp204and facilitates rotation of the piston assembly164relative to at least one of the second housing member172and the bearing assembly162as the piston assembly164moves between the first position and the second position.

The second bearing carrier portion272extends radially outwardly from the first bearing carrier portion270towards the inner annular wall214to define the shoulder216to receive the bearing262.

The bearing262is rotatably supported by the second bearing carrier portion272of the bearing carrier260. A member276is disposed between the second bearing carrier portion272and the bearing262. The member276is at least partially disposed about the bearing262.

The bearing262may be configured as a release bearing or may be configured as the bearing9. The bearing262may include an inner race and an outer race with at least one rolling element disposed between the inner race and the outer race.

The piston assembly164is slidably received within the first housing member170and is configured to selectively change a clutch state of the clutch2that engages the bearing assembly162between an engaged state and a disengaged state. The piston assembly164is movable between a first position and a second position in response to the application of compressed air provided by a pneumatic source. The first position of the piston assembly164may correspond to the engaged state of the clutch2of the clutch assembly1. The second position of the piston assembly164may correspond to the disengaged state of the clutch2of the clutch assembly1.

The piston assembly164includes a piston head280and an (annular extension member) extension member282. The piston head280is disposed adjacent to the base180when the piston assembly164is in the first position. Compressed air that is provided to the pneumatic clutch actuator10moves the piston assembly164from the first position towards the second position. A bottom surface286of the piston head280is spaced apart from the base180when the piston assembly164is in the second position. The bottom surface of the piston head280, the base180, and the inner surface190define a volume288that receives the compressed air. The evacuation or releasing of the compressed air from the volume288enables the piston assembly164to move from the second position towards the first position, as shown inFIG. 5.

The extension member282extends axially from the piston head280towards the bearing assembly162. At least a portion of the extension member282is disposed between the bearing carrier260and the inner annulus184. The extension member282is disposed about inner annulus and slidingly engages the inner annulus outer surface202.

A biasing member284extends between the piston head280and the bearing carrier260. The biasing member284is configured to engage the piston head280and the second bearing carrier portion272to apply a preload to at least one of the piston assembly164and the bearing assembly162.

A portion of the clutch assembly1, such as a diaphragm spring6, is configured to engage the bearing assembly162. The diaphragm spring6operates to engage and/or disengage the clutch assembly1in response to operation of the pneumatic clutch actuator10through the movement of the piston assembly164between the first position and the second position. The clutch disc4has a friction surface that may wear during operation of the clutch assembly1. As the friction surface of the clutch disc4of the clutch2wears, the piston assembly164may travel a greater distance to move between the first position and the second position.

For example, when the piston assembly164moves from the second position towards the first position, the piston head280of the piston assembly164may be spaced apart from the base180at the end of its travel. The spacing apart of the piston head280of the piston assembly164from the base180when in the first position presents a dead volume between the bottom surface286of the piston head280, the base180, and the first annular wall182. The dead volume may require that a pneumatic system supply additional compressed air to move the piston assembly164from the first position towards the second position. The dead volume may result in an increased system response time and decreased system performance due to having to supply the compressed air to fill the dead volume prior to causing the piston assembly164to move between the first position and the second position. In an attempt to overcome these disadvantages, the adjustment assembly166is provided to compensate for the dead volume or to minimize the dead volume in response to wear of the friction surface of the clutch disc of the clutch assembly. The adjustment assembly166is configured to provide a compressive force between the piston assembly164and the bearing assembly162to maintain a predetermined distance or to adjust a distance between the piston assembly164and the first housing member170.

Referring toFIGS. 5, 6, and 9, the adjustment assembly166includes a first adjustment member290and a second adjustment member292. The first adjustment member290is disposed about the bearing carrier260. The first adjustment member290is disposed on or abuts the second shoulder surface252and the second bearing carrier portion272.

The first adjustment member290includes a plurality of first adjustment members300. The plurality of first adjustment members300face towards the piston head280and are configured as an inclined stepped ramp. The plurality of first adjustment members300are inclined in a first direction.

The second adjustment member292is disposed on or abuts the piston head280. The second adjustment member292is disposed annularly about the extension member282and includes a plurality of second adjustment members302in an opposing relationship with the plurality of first adjustment members300. The plurality of second adjustment members302face towards the bearing carrier260of the bearing assembly162and face towards the plurality of first adjustment members300. The plurality of second adjustment members302are configured as an inclined stepped ramp that is complementary to the inclined stepped ramp of the plurality of first adjustment members300. The plurality of second adjustment members302are inclined in a second direction that is disposed opposite the first direction.

The plurality of first adjustment members300and the plurality of second adjustment members302are each inclined at an angle substantially similar to the angle of the ramp204. In at least one embodiment, the angle has the same pitch as the ramp204.

Referring toFIGS. 5 and 7, the relative motion of the protrusion274along the ramp204rotates the piston assembly164relative to the bearing assembly162. In addition, the relative motion between the protrusion274and the ramp204rotates the piston assembly164relative to the second housing member172such that the second adjustment member292rotates relative to the first adjustment member290. The second adjustment member292rotates relative to the first adjustment member290at least until a member of the plurality of first adjustment members300engages a member of the plurality of second adjustment members302. The relative movement between the plurality of first adjustment members300and the plurality of second adjustment members302adjusts a distance between the piston assembly164and the bearing assembly162to compensate for wear of the clutch assembly1.

Referring toFIGS. 6-9, as compressed air is supplied to the pneumatic clutch actuator10, the piston assembly164moves from the first position towards the second position to disengage the clutch2. As the piston assembly164moves towards the bearing assembly162the second adjustment member292moves rotates relative to the first adjustment member290, as shown inFIGS. 6 and 7. The protrusion274rides along the ramp204and rotates the piston assembly164such that the second adjustment member292rotates relative to the first adjustment member290. A member of the plurality of first adjustment members300is disposed proximate and may engage a member of the plurality of second adjustment members302, as shown inFIG. 8.

As shown inFIG. 9, the engagement between the plurality of first adjustment members300and the plurality of second adjustment members302maintains or adjusts a distance between the piston assembly164and the bearing assembly162to be within a predetermined distance. A drag torque from the bearing assembly162may ensure that an adjustment member of the plurality of the first adjustment members300engages an adjustment member of the plurality of the second adjustment members302at a highest position such that the dead volume is at a minimum.

In accordance with a third exemplary embodiment, a pneumatic clutch actuator10is illustrated inFIGS. 10-12.

The pneumatic clutch actuator10is configured to selectively change the state of the clutch assembly1between an engaged state and a disengaged state. The pneumatic clutch actuator10includes a housing400, a cover402, a bearing assembly404, a piston assembly406, and an adjustment assembly408.

The housing400is disposed about the transmission input shaft5that extends along an axis412. The housing400is configured as an annular housing. The housing400includes a floor420, a first housing wall422, a second housing wall424, and an air inlet426.

The floor420is disposed about the transmission input shaft5and is disposed substantially perpendicular to the transmission input shaft5and the axis412. The floor420radially extends between the first housing wall422and the second housing wall424.

The first housing wall422axially extends from the floor420and is disposed substantially perpendicular thereto. The first housing wall422is disposed proximate and is disposed substantially parallel to the shaft410.

The second housing wall424is radially spaced apart from the first housing wall422. The second housing wall424axially extends from the floor420and is disposed substantially perpendicular thereto. The second housing wall424is disposed substantially parallel to the shaft410. The second housing wall424defines a notch428that is disposed proximate an end thereof.

The air inlet426extends through at least a portion of the second housing wall424. The air inlet426is configured to receive compressed air from a pneumatic source and provide the compressed air to an interior portion of the pneumatic clutch actuator10to selectively actuate the pneumatic clutch actuator10.

The cover402is disposed about the transmission input shaft5and the housing400. The cover402is movable relative to the housing400. The cover402includes a first cover wall430, a second cover wall432, an extension wall434, and a shoulder436.

The first cover wall430is disposed about the second housing wall424in a substantially parallel relationship to the second housing wall424.

The second cover wall432is radially spaced apart from the first cover wall430. The second cover wall432is radially disposed between the first cover wall430and the first housing wall422. The extension wall434extends between distal ends of the first cover wall430and the second cover wall432. The extension wall434is disposed substantially perpendicular to the first cover wall430and the second cover wall432. The extension wall434is disposed substantially parallel to the floor420.

The shoulder436extends radially inwardly from the second cover wall432towards the axis412and the first housing wall422. The shoulder436is disposed substantially perpendicular to the second cover wall432. The shoulder436is configured to receive the bearing assembly404.

The bearing assembly404is received within the pocket438and is disposed on the shoulder436and is arranged to move or translate with the cover402in response to actuation of the pneumatic clutch actuator10.

A portion of the clutch2of the clutch assembly1, such as the diaphragm spring6, may engage the bearing assembly404. The diaphragm spring6operates to engage and/or disengage the clutch2in response to operation of the pneumatic clutch actuator10.

The piston assembly406is movable between a first position (FIG. 12) and a second position (FIG. 11) to selectively change a state of the clutch assembly1in response to the application or release of compressed air provided from the pneumatic source.

The piston assembly406includes a piston head440, an extension member442, and a piston skirt444.

The piston head440radially extends between the extension member442and the piston skirt444and is disposed adjacent the floor420when the piston assembly406is in the first position, as shown inFIG. 12. The provision of compressed air through the air inlet426moves the piston assembly406from the first position towards the second position.

The piston head440is spaced apart from the floor420when the piston assembly406is in the second position, as shown inFIG. 11. The piston head440, the floor420, the first housing wall422, and the second housing wall424at least partially define a volume446that receives the compressed air. The evacuation or releasing of the compressed air from the volume446enables the piston assembly406to move from the second position towards the first position, as shownFIG. 12.

The extension member442is disposed about the first housing wall422. The extension member442extends axially from the piston head440and is disposed proximate and is disposed substantially parallel to the first housing wall422. The extension member442sealingly engages the first housing wall422.

The piston skirt444is radially spaced apart from the extension member442. The piston skirt444is disposed substantially parallel to and is disposed proximate the second housing wall424. The piston skirt444sealingly engages the second housing wall424.

The piston skirt444defines a first engagement surface450that is disposed at an end of the piston skirt444. The first engagement surface450is configured as a conical surface, a chamfered surface, a ramped surface, or the like. The first engagement surface450is disposed in a nonparallel and a non-perpendicular relationship with respect to the piston skirt444and or the piston head440.

As the friction surface of the clutch disc4of the clutch2wears, the piston assembly406may, without adjustment, travel a greater distance to move between the first position and the second position. For example, when the piston assembly406moves from the second position towards the first position, the piston head440of the piston assembly406may be spaced apart from the floor420even when the compressed air is substantially evacuated from the volume446due to the wearing of the friction surface of the clutch disc4of the clutch2. The spacing apart of the piston head440from the floor420while the piston assembly406is in the first position presents a dead volume within the volume446. The dead volume may result in an increased clutch assembly1system response time and decreased system performance. In an attempt to overcome these disadvantages, the adjustment assembly408adjusts a distance between the piston assembly406and the bearing assembly404to eliminate the dead volume.

The adjustment assembly408is disposed between the cover402and the piston assembly406and is disposed about a portion of the piston assembly406. The adjustment assembly408is configured to, or is arranged to; adjust a distance between the piston assembly406and the bearing assembly404to maintain consistent performance of the pneumatic clutch actuator10. The adjustment assembly408includes a sleeve adjuster460and a conical adjuster462.

The sleeve adjuster460is radially disposed between the extension member442and the conical adjuster462. The sleeve adjuster460is axially disposed between the shoulder436of the cover402and the piston head440of the piston assembly406. The sleeve adjuster460includes a first portion470, a second portion472, and a third portion474. The first portion470is disposed proximate and annularly encompasses the extension member442of the piston assembly406.

The second portion472is radially spaced apart from the first portion470and is disposed substantially parallel thereto. The second portion472is arranged to selectively engage the conical adjuster462through a plurality of first engagement elements480defined by the second portion472. The plurality of first engagement elements480are disposed on a surface of the second portion472that face outwardly towards the second housing wall424. The plurality of first engagement elements480are configured as teeth, protrusions, fingers, threads, or the like.

The third portion474radially extends between the first portion470and the second portion472. The third portion474is disposed substantially perpendicular to the first portion470and the second portion472. The third portion474is configured to engage the shoulder436of the cover402.

The conical adjuster462is disposed about the sleeve adjuster460and is radially disposed between the second housing wall424and the sleeve adjuster460. The conical adjuster462is axially disposed between the cover402and the piston assembly406. The conical adjuster462includes an adjuster wall490, a lip492, and an adjuster arm494. The adjuster wall490is disposed proximate and is disposed substantially parallel to the second housing wall424. The adjuster wall490is disposed substantially parallel to the first portion470and the second portion472.

The lip492extends from a first end500of the adjuster wall490and extends towards the first cover wall430. The lip492is disposed substantially perpendicular to the adjuster wall490and extends over a portion of the second housing wall424.

The adjuster arm494extends from a second end502of the adjuster wall490and is configured to selectively engage the second portion472of the sleeve adjuster460.

The adjuster arm494defines a second engagement surface510and a plurality of second engagement elements512. The second engagement surface510is disposed on a face of the adjuster arm494that faces towards and end of the piston skirt444. The second engagement surface510is configured as a conical surface, a chamfered surface, a ramped surface, or the like that is complementary to the first engagement surface450. The second engagement surface510is configured to selectively engage or slide along the first engagement surface450.

The plurality of second engagement elements512are disposed on a face of the adjuster arm494that faces towards the plurality of first engagement elements480of the second portion472. The plurality of second engagement elements512are disposed adjacent to the face that includes the second engagement surface510. The plurality of second engagement elements512are configured to selectively engage the plurality of first engagement elements480.

Engagement between the first engagement surface450and the second engagement surface510as well as engagement between the plurality of first engagement elements480and the plurality of second engagement elements512define a load path through the piston assembly406, the adjustment assembly408, and the cover402to the bearing assembly404and ultimately the clutch assembly1. As such, the first engagement surface450being engaged with the second engagement surface510as well as the plurality of the first engagement elements480being engaged with the plurality of second engagement elements512provides a rigid connection between the piston assembly406, the conical adjuster462, the sleeve adjuster460, the cover402, and the bearing assembly404such that the movement of the piston assembly406from the first position towards the second position, as shown inFIG. 11, moves the bearing assembly404to move the clutch assembly1from a disengaged state towards an engaged state when compressed air is applied to the pneumatic clutch actuator10.

The release of the compressed air from the pneumatic clutch actuator10enables the piston assembly406to move from the second position towards the first position as the clutch assembly1moves from the engaged state to towards the disengaged state. A first biasing member514and a second biasing member516are provided with the adjustment assembly408, to ensure the elimination of a dead volume between the piston head440of the piston assembly406and the floor420of the housing400.

The first biasing member514is disposed between the sleeve adjuster460and the piston assembly406and is arranged to bias the piston head440of the piston assembly406towards the floor420. The rigid connection between the piston assembly406, the conical adjuster462, the sleeve adjuster460, the cover402, and the bearing assembly404is severed, when the first engagement surface450engages the second engagement surface510, to facilitate the biasing of the piston head440of the piston assembly406towards the floor420of the housing400.

As shown inFIG. 12, the engagement of the lip492of the conical adjuster462with the second housing wall424of the housing400while the piston assembly406continues to move towards the first position to eliminate the dead volume, the second engagement surface510rides along the first engagement surface450. The riding of the second engagement surface510along the first engagement surface450causes the conical adjuster462to radially displace towards the second housing wall424such that the plurality of second engagement elements512disengage from the plurality of first engagement elements480. The disengagement of the plurality of first engagement elements480from the plurality of second engagement elements512facilitates the first biasing member514to urge or bias the piston assembly406towards the floor420to eliminate the dead volume.

A second biasing member516extends between the cover402and the conical adjuster462and engages the extension wall434and the adjuster arm494. The second biasing member516is arranged to bias or urge the second engagement surface510of the adjuster arm494into engagement with the first engagement surface450.

In accordance with a fourth exemplary embodiment, a pneumatic clutch actuator10is illustrated inFIGS. 13-18.

Referring toFIGS. 13, 14, 15A, 15B, 16A, 16B, 17A-17C, and 18the pneumatic clutch actuator10is configured to selectively change the state of the clutch2of the clutch assembly1that is operatively connected to the pneumatic clutch actuator10between an engaged state and a disengaged state.

The pneumatic clutch actuator10includes a housing assembly610, a bearing assembly612, a piston assembly614, and an adjustment assembly616.

The housing assembly610is circumferentially disposed about the transmission input shaft5and is configured as an annular housing. The housing assembly610includes a first housing member620and a second housing member622. The first housing member620is at least partially received within the second housing member622and includes a base630, a first annular wall632, and an inner annulus634. The base630is disposed about the transmission input shaft5. The first annular wall632extends from the base630and includes an inner surface640and an outer surface642.

The inner annulus634extends axially from the base630and is spaced apart from the first annular wall632. The inner annulus634extends from the base630towards and through the second housing member622. The inner annulus634is disposed substantially concentric with the first annular wall632and includes an inner annulus inner surface650and an inner annulus outer surface652. The inner annulus inner surface650defines a bore within which the transmission input shaft5is received. The inner annulus634extends along an axis658. In at least one embodiment, a sealing boot or dust cover659is disposed about a portion of the inner annulus634and engages the inner annulus outer surface652. The dust cover659engages a portion of a bearing carrier710and is received within a groove defined by the inner annulus outer surface652.

The second housing member622is at least partially disposed about the first housing member620and may be configured as an environmental cover to protect components disposed within the first housing member620from the ingress of contaminants.

The second housing member622includes an outer annular wall660, an extension wall662, an inner annular wall664, and a shoulder666. The outer annular wall660is disposed substantially parallel to the first annular wall632and includes a second annular wall inner surface670and a second annular wall outer surface672. The second annular wall inner surface670is disposed proximate to and faces towards the outer surface642.

The extension wall662connects the outer annular wall660and the inner annular wall664. The extension wall662is disposed substantially perpendicular to the outer annular wall660and is disposed substantially parallel to the base630. The extension wall662includes an extension wall inner surface680and an extension wall outer surface682.

The inner annular wall664extends from the extension wall662and includes a third annular wall inner surface690and a third annular wall outer surface692. The second annular wall inner surface670, the extension wall inner surface680, and the third annular wall inner surface690define an annular cavity694. In at least one embodiment, the annular cavity694is sized to at least partially receive the first annular wall632.

The shoulder666extends radially inward (with respect to the axis658) from the inner annular wall664towards the inner annulus634. The shoulder666is disposed substantially perpendicular to the inner annular wall664and is disposed substantially parallel to the extension wall662. The shoulder666includes a first shoulder surface700and a second shoulder surface702. The first shoulder surface700faces away from the base630. The second shoulder surface702faces towards the base630.

The bearing assembly612is at least partially received within the housing assembly610and is disposed about the inner annulus634. The bearing assembly612includes a bearing carrier710and a bearing712.

The bearing carrier710is slidably disposed about the inner annulus outer surface652. The bearing carrier710slides along the inner annulus outer surface652in response to movement of the piston assembly614or in response to the application of a force or load onto the bearing assembly612by the diaphragm spring6.

The bearing carrier710includes a first bearing carrier portion720, a second bearing carrier portion722, and a third bearing carrier portion724. The first bearing carrier portion720is disposed radially between the inner annulus634and the bearing assembly612and is disposed substantially parallel to the inner annulus634.

The second bearing carrier portion722extends radially outwardly from the first bearing carrier portion720to the third bearing carrier portion724. The second bearing carrier portion722is disposed axially (with respect to the axis658) between the bearing assembly612and the adjustment assembly616. The second bearing carrier portion722defines a bearing shoulder.

The third bearing carrier portion724extends from the second bearing carrier portion722. The third bearing carrier portion724is disposed substantially perpendicular to the second bearing carrier portion722and is disposed substantially parallel to the first bearing carrier portion720. The third bearing carrier portion724extends into a portion of the adjustment assembly616such that the bearing carrier710, the portion of the adjustment assembly616, and the piston assembly614are linked together to inhibit or restrict unintentional rotation between the parts, as shown inFIGS. 14, 16A, and 16B.

The bearing712is rotatably supported by the second bearing carrier portion722. A portion of the shoulder666is disposed between and engages portions of the second bearing carrier portion722and the bearing712. A member726extends between the bearing712and the bearing carrier710. The member726is connected to a portion of the bearing712and the second bearing carrier portion722. The bearing712may be configured as a release bearing. The bearing712may include an inner race and an outer race with at least one rolling element disposed between the inner race and the outer race.

The piston assembly614is slidably received within the first housing member620. The piston assembly614is configured to selectively change a clutch state of a clutch2that engages the bearing assembly612between an engaged state and a disengaged state. The piston assembly614is movable between a first position (FIG. 17A) and a second position (FIG. 17C) in response to the application of compressed air provided from a pneumatic source. The first position of the piston assembly614may correspond to the engaged state of the clutch2of the clutch assembly1(FIG. 1A). The second position of the piston assembly614may correspond to the disengaged state of the clutch2of the clutch assembly1(FIG. 1B).

The piston assembly614includes a piston head730, a first extension member732, a second extension member734, and a first adjustment member736. The piston head730is disposed adjacent to the base630when the piston assembly614is in the first position. Compressed air that is provided to the pneumatic clutch actuator10moves the piston assembly614from the first position towards the second position. A bottom surface of the piston head730is spaced apart from the base630when the piston assembly614is in the second position, as shown inFIG. 17C. The bottom surface of the piston head730, the base630, and the inner surface640define a volume738that receives the compressed air. The evacuation or releasing of the compressed air from the volume738enables the piston assembly614to move from the second position towards the first position, as shown inFIG. 14.

The first extension member732extends axially from the piston head730towards the bearing assembly612. At least a portion of the first extension member732is disposed between the bearing carrier710and the inner annulus634. The second extension member734is radially spaced apart from the first extension member732. The second extension member734extends axially from the piston head730towards the second housing member622. The second extension member734and the piston head730at least partially define a recess740.

The first adjustment member736is at least partially received within the recess740. The first adjustment member736extends towards the bearing carrier710.

A portion of the clutch assembly1, such as a diaphragm spring6, may be configured to engage the bearing assembly612. The diaphragm spring6operates to engage and/or disengage the clutch assembly in response to operation of the pneumatic clutch actuator10through the movement of the piston assembly614between the first position and the second position. The clutch2includes a clutch disc4that has a friction surface that may wear during operation to selectively engage or disengage the clutch assembly1. As the friction surface of the clutch disc4of the clutch2wears the relative starting position of the bearing712may change.

As the piston assembly614moves from the second position towards the first position, the piston head730of the piston assembly614may be spaced apart from the base630at the end of its travel. The spacing apart of the piston head730from the base630when in the first position presents a dead volume between the bottom surface of the piston head730, the base630, and the first annular wall632. The dead volume may require that a pneumatic system supply additional compressed air to move the piston assembly614from the first position towards the second position. The dead volume may result in a decreased system response time and decreased system performance. In an attempt to overcome these disadvantages, the adjustment assembly616is provided to compensate for the dead volume or to minimize the dead volume in response to wear of the friction surface of the clutch disc of the clutch assembly such that the piston assembly614has a substantially consistent starting position throughout the life to the pneumatic clutch actuator10.

The adjustment assembly616includes a guide member750, a second adjustment member752, a friction pad754, a first low friction interface component756, a second low friction interface component758, and a biasing member760. In at least one embodiment, the first adjustment member736is provided as part of the adjustment assembly616. In at least one embodiment, the first adjustment member736is provided as part of the piston assembly614and is attached to the piston head730.

The guide member750is radially disposed between the first annular wall632and the second adjustment member752. The guide member750is axially disposed between the piston assembly614and the extension wall662of the second housing member622.

The guide member750includes a guide body770and a lip772. The guide body770defines an adjustment ramp780that is inclined toward or is declined away from the lip772.

The lip772extends from the guide body770towards the outer annular wall660of the second housing member622. The lip772is configured to selectively engage a portion of the first annular wall632. The lip772engages the first annular wall632as the piston assembly614moves towards the base630of the first housing member620(e.g. towards the first position). The lip772is spaced apart from the first annular wall632as the piston assembly614moves away from the base630of the first housing member620(e.g. towards the second position).

The second adjustment member752is disposed about the inner annulus634. The second adjustment member752is axially disposed between the bearing carrier710and the first adjustment member736or the piston assembly614. The second adjustment member752includes a first portion790, a second portion792, and a third portion794.

The second portion792extends from and is disposed substantially perpendicular to the first portion790. In at least one embodiment, the second portion792is disposed proximate the second bearing carrier portion722.

The second portion792defines a region796that is sized to receive the first low friction interface component756. The first low friction interface component756is slidingly or rollingly disposed between the second bearing carrier portion722of the bearing carrier710and the second portion792of the second adjustment member752. The first low friction interface component756provides a low friction interface between the bearing carrier710and the second adjustment member752.

The third portion794extends from the second portion792towards the first adjustment member736. The third portion794is disposed substantially perpendicular to the second portion792and is disposed substantially parallel to the first portion790. The third portion794is configured as a notch or is provided with a general chevron shape that is arranged to receive the first adjustment member736that is configured as a wedge or complementary chevron shape to the general chevron shape of the third portion794.

The second low friction interface component758extends from the third portion794and is configured to move or slide relative to the adjustment ramp780of the guide member750.

The third portion794defines a friction surface800. The friction surface800is configured as a stepped interface or a ramp that is inclined towards or is declined away from the second portion792of the second adjustment member752. The friction surface800has a substantially similar pitch as the adjustment ramp780but is inclined or declined in a direction complementary to the inclination or declination of the adjustment ramp780. The friction surface800is configured to at least partially receive the friction pad754that is disposed on a portion of the first adjustment member736. The friction pad754is configured to selectively engage the friction surface800as the piston assembly614moves towards the second adjustment member752.

The biasing member760is disposed between the piston assembly614and the second adjustment member752. The biasing member760is configured to engage the piston head730of the piston assembly614and the second portion792of the second adjustment member752. The biasing member760is configured to provide a torsional/rotational biasing force and an axial biasing force. The biasing member760is arranged to impart a rotational force to the second adjustment member752as the piston assembly614moves towards the base630of the first housing member620. The rotational force causes the second adjustment member752to rotate relative to the guide member750such that the second low friction interface component758rides or runs along the adjustment ramp780of the guide member750to adjust a total length of the piston assembly614along the axis658, as shown inFIGS. 13, 15A, and 16A-16B.

Referring toFIGS. 15A-15B, a portion of the clutch2, such as a diaphragm spring6, is configured to engage the bearing assembly612. The diaphragm spring6may apply a load or a force to the bearing assembly612such that the second adjustment member752moves towards the first adjustment member736. The biasing member760applies a biasing force such that the second adjustment member752attempts to rotate relative to the guide member750to adjust the total length of the piston assembly614.

Referring toFIGS. 17A-17C, as compressed air is supplied to the pneumatic clutch actuator10, the piston assembly614moves from the first position towards the second position to disengage the clutch2, as shown inFIG. 17A. As the piston assembly614moves towards the bearing assembly612, the friction pad754disposed on the first adjustment member736engages the friction surface800of the second adjustment member752, as shown inFIG. 17B. The engagement of the friction pad754with the friction surface800inhibits relative rotation between the second adjustment member752, the first adjustment member736, and the piston assembly614and enables the piston assembly614to move the guide member750and the bearing carrier710to move the bearing assembly612, as shown inFIG. 17C.

Referring toFIGS. 13, 14, 15A, and 15B, when compressed air is no longer supplied to the pneumatic clutch actuator10, the diaphragm spring6and/or the biasing member760urges the piston assembly614to move from the second position towards the first position to engage the clutch2. As the piston assembly614moves towards the base630of the first housing member620the lip772engages the first annular wall632causing the friction pad754disposed on the first adjustment member736to separate from the friction surface800of the second adjustment member752enabling the second adjustment member752to rotate relative to the guide member750such that the second low friction interface component758rides along the adjustment ramp780of the guide member750to maintain or adjust a total length of the piston assembly614to minimize the dead volume or maintain a substantially constant stroke of the piston assembly614.