Dual actuation ball contour synchronizing clutch

A dual actuation synchronizing clutch assembly including an improved synchronization arrangement is provided. The dual actuation synchronizing clutch assembly has a plurality of operational phases, including initial, synchronization, positioning, engagement, and running phases that vary the torque flow path between the input shaft and output shaft. A synchronizing assembly is provided that includes a synchronizer ring having a first friction surface and synchronizer teeth. A connecting gear includes a lock-up assembly with retractable elements and connecting gear teeth. An output gear includes a second friction surface configured to frictionally engage the first friction surface of the synchronizer ring, and a contoured receiving path with positioning points configured to receive the retractable elements of the lock-up assembly.

FIELD OF INVENTION

The present invention relates to a clutch and is more particularly related to a synchronizer assembly for a clutch.

BACKGROUND

Clutches are provided to connect and disconnect all-wheel drive (AWD) systems through a power transfer unit (PTU) or a rear drive unit (RDU). One known type of clutch is used in an automobile to switch between AWD and two wheel drive (2WD) mode. In these known clutches, it is necessary to synchronize the speeds between an input shaft and output shaft. A variety of synchronization assemblies are provided to synchronize the speeds of the input shaft and output shaft. However, these known synchronization assemblies can cause chatter, clashing, and/or grinding of the synchronizing components, which results in undesirable wear to the clutch components.

It would be desirable to provide a compact assembly that provides a smooth and quiet synchronization arrangement between the input shaft and output shaft.

SUMMARY

An improved synchronization assembly is provided that increases synchronizing efficiency, reduces misalignment between components being synchronized, and prevents wear and damage to these components. The improved synchronization assembly also reduces the distance required for synchronizing components to move between phases, and improves the life cycle of synchronization components, such as the clutch springs and lock-up assembly components.

A dual actuation synchronizing clutch assembly is provided that includes an input shaft and a rotatably supported output shaft axially aligned with the input shaft. A connecting gear includes a lock-up assembly with retractable elements and connecting gear teeth, and the connecting gear is connected to the input shaft. A first actuator is configured to engage a first actuator loading bearing axially against the connecting gear. A synchronizer ring includes a first friction surface and synchronizer teeth. An output gear is fixed to the output shaft, and the output gear includes output gear teeth and a second friction surface configured to frictionally engage the first friction surface of the synchronizer ring. A contoured receiving path of the output gear includes positioning points configured to receive retractable elements of the lock-up assembly. A shifter sleeve includes shifter sleeve teeth that mesh with the connecting gear teeth and the synchronizer teeth, and the shifter sleeve teeth are configured to mesh with the output gear teeth. A second actuator is configured to engage a second actuator loading bearing axially against the shifter sleeve. A first spring is arranged between the synchronizer ring and the output gear, a second spring is arranged between the connecting gear and the synchronizer ring, and a third spring biases the shifter sleeve to a disengaged position. The dual actuation synchronizing clutch assembly has a plurality of operational phases. During an initial phase, the first and second actuators are deactivated, and the first, second, and third springs are in an expanded state such that the input shaft and the output shaft are rotatable independently from each other. During a synchronization phase, the first actuator is in a first actuation mode, the first spring and the second spring are at least partially compressed, and the first friction surface of the synchronizer ring engages the second friction surface of the output gear. During the synchronization phase, a torque flow path is provided between the input shaft and the output shaft via the first and second friction surfaces of the synchronizer ring and the output gear. During a positioning phase, the first actuator is in a second actuation mode, and at least the second spring is further compressed than in the synchronization phase, the retractable elements of the lock-up assembly engage in the positioning points of the contoured receiving path of the output gear, and the first friction surface of the synchronizer ring remains engaged with the second friction surface of the output gear. During the positioning phase, the torque flow path is at least partially provided between the input shaft and the output shaft via the lock-up assembly of the connecting gear engaging the output gear, and the shifter sleeve teeth are aligned with the output gear teeth. During an engagement phase, the first actuator is in the second actuation mode and the second actuator is actuated, the third spring is at least partially compressed, the retractable elements of the lock-up assembly remain engaged in the positioning points of the contoured receiving path of the output gear, and the shifter sleeve teeth engage the output gear teeth. During the engagement phase, the torque flow path is provided between the input shaft and the output shaft via the output gear teeth and the shifter sleeve teeth. During a running phase, the first actuator is deactivated and the second actuator remains actuated, and the first spring and the second spring return to an expanded state and the third spring remains at least partially compressed, so that the first friction surface of the synchronizer ring is disengaged from the second friction surface of the output gear, the retractable elements of the lock-up assembly disengage from the positioning points of the contoured receiving path of the output gear, and the shifter sleeve teeth remain engaged with the shifter sleeve teeth. During the running phase, the torque flow path is provided between the input shaft and the output shaft via the output gear teeth and the shifter sleeve teeth.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Certain terminology is used in the following description for convenience only and is not limiting. The words “front,” “rear,” “upper,” and “lower” designate directions in the drawings to which reference is made. The words “inwardly” and “outwardly” refer to directions toward and away from the parts referenced in the drawings. “Axially” refers to a direction along the axis of a shaft or rotating part. A reference to a list of items that are cited as “at least one of a, b, or c” (where a, b, and c represent the items being listed) means any single one of the items a, b, or c, or combinations thereof. The terminology includes the words specifically noted above, derivatives thereof and words of similar import.

As shown inFIGS. 1, 2, and 4A-4E, a dual actuation synchronizing clutch assembly1is provided. The dual actuation synchronizing clutch assembly1includes an input shaft2and a rotatably supported output shaft4axially aligned with the input shaft2. Preferably, a shaft support bearing13is provided between the input shaft2and the output shaft4. The input shaft2preferably includes input shaft splines3. As shown inFIG. 1, at least one shaft seal9is provided between the input shaft2and a housing11. The dual action synchronizing clutch assembly1includes a connecting gear6that has a lock-up assembly8with retractable elements10and connecting gear teeth12, and the connecting gear6is connected rotationally fixed to the input shaft2. The connecting gear6preferably includes connecting gear splines7meshed with the input shaft splines3. The output gear24includes output gear splines25that mesh with the output shaft4via output shaft splines5. A snap ring15preferably engages the input shaft2and axially positions the connecting gear6with respect to the input shaft2.

A first actuator14configured as a hydraulically actuated annular piston engages a first actuator loading bearing16axially against the connecting gear6. A synchronizer ring18includes a first friction surface20and synchronizer teeth22. An output gear24is fixed to the output shaft4, and the output gear24includes a second friction surface26configured to be frictionally engaged by the first friction surface20of the synchronizer ring18. The first friction surface20of the synchronizer ring18and the second friction surface26of the output gear24each preferably have a frusto-conical profile. As shown inFIG. 2, the synchronizer ring18includes synchronizer ring splines19that mate with the input shaft splines3.

As shown inFIG. 3, the output gear24includes a contoured receiving path28with positioning points30a-30heach configured to receive the retractable elements10of the lock-up assembly8. Although the output gear24is shown with eight positioning points30a-30hin the Figures, one of ordinary skill in the art will recognize that any number of positioning points can be used. The output gear24also includes output gear teeth32, which are provided for driving engagement with shifter sleeve34, described below. As shown inFIGS. 1 and 2, a thrust washer21and a thrust bearing23are provided between the synchronizer ring18and the output shaft4and the output gear24.

The lock-up assembly8preferably includes a plurality of cups27each having a ball29, and the positioning points30a-30hof the contoured receiving path28of the output gear24include pockets31a-31hto receive the balls29. Preferably, the lock-up assembly8includes three cups27and balls29. One of ordinary skill in the art would recognize that the number of cups27and balls29, as well as the arrangement of the cups27and balls29, can be varied.

A shifter sleeve34includes a shifter ring35with shifter sleeve teeth36that mesh with the connecting gear teeth12and the synchronizer teeth22. The shifter sleeve teeth36are also configured to mesh with the output gear teeth32. The output gear teeth32are preferably arranged on a radially outer surface33of the output gear24, and the shifter sleeve teeth36are preferably arranged on a radially inner surface37of the shifter ring35. A second actuator38, preferably configured as a hydraulically actuated annular piston, engages a second actuator loading bearing40axially against the shifter sleeve34. The first and second actuators14,38are preferably hydraulic actuators, however one of ordinary skill in the art would recognize that other types of actuators can be used, such as magnetic or mechanical actuators. A first spring42is arranged between the synchronizer ring18and the output gear24. A second spring44is arranged between the connecting gear6and the synchronizer ring18. A third spring46biases the shifter sleeve34to a disengaged position.

A schematic view of a section of the profile of the contours of the contoured receiving path28of the output gear24is shown inFIGS. 3A and 3B. The contoured receiving path28is formed as an annular groove or recess and has a contour slope angle (β), a contour diameter (Dc) shown inFIG. 3, and a contour height (hc). The following relationships are provided for the arrangement and design of the lock-up assembly8:
Ft=Fa*tan(β)
Tr=0.5n*Ft*Dc=0.5n*Fa*Dc*tan(β)
Fa=2Tr/[n*Dc*tan(β)]
Fr=n*Fa=2Tr/[Dc*tan(β)]
wherein (Ft) corresponds to a required position force, (Tr) corresponds to a torque required for rotating the output gear24, (n) corresponds to a number of retractable elements10.FIG. 3Acorresponds to a first embodiment of the contoured receiving path28including one set of contours, andFIG. 3Bcorresponds to a second embodiment of the contoured receiving path28′ including two sets of contours. The contour slope angle (β′) ofFIG. 3Bis approximately two times of the contour slope angle (β) ofFIG. 3A. (FN) corresponds to a normal force of the retractable element10on the contoured receiving path28, and (Ft) corresponds to a traction force experienced by the retractable elements10along the contoured receiving path28.

The dual actuation synchronizing clutch assembly1has a plurality of operational phases, shown inFIGS. 4A-4E. The use of these phases helps reduce the wear on the retractable elements10, and the springs42,44,46, as well as helps reduce the lag time between switching from a running phase, during which the input shaft2and output shaft4are connected, to an initial phase, during which the input shaft2and the output shaft4are disconnected.

In an initial phase, shown inFIGS. 4A and 7A, the first actuator14and the second actuator38are deactivated, and the first spring42, the second spring44, and the third spring46are in an expanded state such that the input shaft2and the output shaft4are rotatable independently from each other.

In a synchronization phase, shown inFIGS. 4B and 7B, the first actuator14is in a first actuation mode. The second actuator38remains deactivated in this phase. The first spring42and the second spring44are at least partially compressed with the first spring42preferably being compressed to a maximum compression state, and the first friction surface20of the synchronizer ring18engages the second friction surface26of the output gear24, and a torque flow path is provided between the input shaft2and the output shaft4via the first and second friction surfaces20,26of the synchronizer ring18and the output gear24.

In a positioning phase, shown inFIGS. 4C and 7C, the first actuator14is in a second actuation mode. The second actuator38remains deactivated in this phase. In this phase, at least the second spring44is further compressed than in the synchronization phase. The retractable elements10of the lock-up assembly8engage in at least some of the positioning points30a-30hof the contoured receiving path28of the output gear24, and the first friction surface20of the synchronizer ring18remains engaged with the second friction surface26of the output gear24. The torque flow path is at least partially provided between the input shaft2and the output shaft4via the lock-up assembly8of the connecting gear6engaging the output gear24. Here, the shifter sleeve teeth36are aligned with the output gear teeth32via the balls29being located in the position points30a-30h.

In an engagement phase, shown inFIGS. 4D and 7D, the first actuator14is in the second actuation mode and the second actuator38is actuated. The third spring46is at least partially compressed due to the force from the second actuator38. The retractable elements10of the lock-up assembly8remain engaged in the positioning points30a-30hof the contoured receiving path28of the output gear24, and the output gear teeth32engage the shifter sleeve teeth36, such that the torque flow path is provided between the input shaft2and the output shaft4via the shifter sleeve teeth36engaging the output gear teeth32.

In a running phase, shown inFIGS. 4E and 7E, the first actuator14is deactivated and the second actuator38remains actuated. The first spring42and the second spring44return to an expanded state and the third spring46remains at least partially compressed. The first friction surface20of the synchronizer ring18is disengaged from the second friction surface26of the output gear24. The retractable elements10of the lock-up assembly8are disengaged from the positioning points30a-30hof the contoured receiving path28of the output gear24. The shifter sleeve teeth36remain engaged with the output gear teeth32, such that the torque flow path is provided between the input shaft2and the output shaft4via the shifter sleeve teeth36and the output gear teeth32.

To disengage the output gear teeth32from the shifter sleeve teeth36, the second actuator38is deactivated, and the third spring46axially biases the shifter sleeve34. This axial movement of the shift sleeve34causes the output gear teeth32to disengage the shifter sleeve teeth36, eliminating the torque flow path between the input shaft2and the output shaft4. The shift sleeve34only needs to axially move slightly more than a tooth width of the output gear teeth32. This provides a much shorter shifting distance than known synchronizer arrangements, and as a result the third spring46can have a lower stiffness and the second actuator38does not need to be as strong as the prior art.

FIG. 5Ashows an alternative embodiment of the synchronizer ring18′, which lacks synchronizer ring splines19for mating with the input shaft splines3. In this embodiment, the rotational motion from the input shaft2is provided from the shifter sleeve teeth36of the shifter ring35to the synchronizer teeth22of the synchronizer ring18′

FIG. 5Bshows an alternative embodiment of the friction surfaces of the synchronizer ring18″ and the output gear24′. In the embodiment shown inFIG. 5B, a first cone18ais provided for the synchronizer ring18″ and a second cone24ais provided for the output gear24′. These cones18a,24aprovide additional contact surface area between the synchronizer ring18″ and the output gear24′ to improve the transfer of torque between these components. One of ordinary skill in the art would recognize that additional cones can be used and alternative arrangements of the cones can be used, depending on spatial requirements, to increase the torque transfer.

FIG. 6Ashows an alternative embodiment of the lock-up assembly8′, including a cup8a, a ball29′, and a ball support8b. This embodiment provides a simple arrangement since the cup8ais deep drawn.FIG. 6Bshows an alternative embodiment of the third spring46′. The third spring46′ ofFIG. 6Bis a cone-shape coil spring. One of ordinary skill in the art would recognize that alternative arrangements of the first, second, and/or third springs can be used as long as the stiffness and shifting distance requirements are met.

As shown inFIGS. 8A and 8B, a synchronizing assembly100for a clutch is provided. The synchronizing assembly100includes a synchronizer ring102including a first friction surface104and synchronizer teeth106. A connecting gear108includes a lock-up assembly110with retractable elements112, and connecting gear teeth114. An output gear116includes a second friction surface118configured to frictionally engage the first friction surface104of the synchronizer ring102. The output gear116includes a contoured receiving path120with positioning points122is configured to receive the retractable elements112of the lock-up assembly110. Actuation of the connecting gear108would result in the retractable elements112engaging the contoured receiving path120with the balls29engaged in the positioning points of the path120to synchronize the connecting gear108, and an associated drive shaft, with the output gear116, and an associated output shaft.

Having thus described the present invention in detail, it is to be appreciated and will be apparent to those skilled in the art that many physical changes, only a few of which are exemplified in the detailed description of the invention, could be made without altering the inventive concepts and principles embodied therein. It is also to be appreciated that numerous embodiments incorporating only part of the preferred embodiment are possible which do not alter, with respect to those parts, the inventive concepts and principles embodied therein. The present embodiment and optional configurations are therefore to be considered in all respects as exemplary and/or illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all alternate embodiments and changes to this embodiment which come within the meaning and range of equivalency of said claims are therefore to be embraced therein.