Wedge clutch with a split hub

A bi-directional wedge clutch, including: an outer race; first and second inner hubs; a wedge plate, radially located between the outer race and the inner hubs; and an axially displaceable activation hub engaged with the inner hubs and arranged to: for a free-wheel mode, rotate at least one of the inner hubs in a first rotational direction, with respect to the other of the inner hubs, such that the wedge plate is free of contact with the outer race; and for a locking mode, rotate the at least one of the inner hubs in a second rotational direction, opposite the first rotational direction, with respect to the other of the inner hubs, to non-rotatably connect the wedge plate with the outer race and the inner hubs.

TECHNICAL FIELD

The present disclosure relates to a bi-directional or one-way wedge clutch that enables switching between engaged and disengaged modes. In particular, the clutch has two inner hubs, rotatable with respect to each other, to enable switching between locking and free-wheel modes.

BACKGROUND

To provide a consistent transition from a free-wheel mode to a locking mode in a bi-directional clutch, it is known to maintain some frictional contact between components of the clutch, such as the inner or outer race, and a rotationally displaceable locking element, in order to displace the locking element to initiate a locking mode. The frictional contact results in torque drag between the inner and outer races and subsequent energy dissipation and decrease in efficiency during operation in free-wheel mode.

SUMMARY

According to aspects illustrated herein, there is provided a bi-directional wedge clutch, including: an outer race; first and second inner hubs; a wedge plate, radially located between the outer race and the first and second inner hubs; and an axially displaceable activation hub engaged with the first and second inner hubs and arranged to: for a free-wheel mode, rotate at least one of the first or second inner hubs in a first rotational direction, with respect to the other of the first or second inner hubs, such that the wedge plate is free of contact with the outer race; and for a locking mode, rotate the at least one of the first or second inner hubs in a second rotational direction, opposite the first rotational direction, with respect to the other of the first or second inner hubs, to non-rotatably connect the wedge plate with the outer race and the first and second inner hubs.

According to aspects illustrated herein, there is provided a bi-directional wedge clutch, including: an outer race; first and second inner hubs; a wedge plate, radially located between the outer race and the first and second inner hubs; and an activation hub. The first inner hub includes a first plurality of slots or a first plurality of protrusions. The second inner hub includes a second plurality of slots or a second plurality of protrusions. The activation hub includes third and fourth pluralities of slots, third and fourth pluralities of protrusions, or a third plurality of slots and a third plurality of protrusions. Respective slots or protrusions for the first and second inner hubs are engaged with respective slots or protrusions for the activation hub. The activation hub is arranged to: for a free-wheel mode, rotate at least one of the first or second inner hubs in a first rotational direction, with respect to the other of the first or second inner hubs, such that the outer race is rotatable with respect to the first and second inner hubs in the first rotational direction and in a second rotational direction, opposite the first rotational direction; and for a locking mode, rotate the at least one of the first or second inner hubs in the second rotational direction, with respect to the other of the first or second inner hubs, to non-rotatably connect the wedge plate with the outer race and the first and second inner hubs for rotation of the outer race, with respect to the first and second inner hubs, in the first and second rotational directions.

According to aspects illustrated herein, there is provided a bi-directional wedge clutch, including: an outer race; a first inner hub including a first plurality of radially extending ramps; a second inner hub including a second plurality of radially extending ramps; a wedge plate, radially located between the outer race and the first and second inner hubs; and an activation hub including first and second pluralities of protrusions. One of the first or second inner hubs includes a first plurality of slots circumferentially bending in a first or second axial direction and engaged with the first plurality of protrusions. The other of the first or second inner hubs includes a second plurality of axially aligned slots engaged with the second plurality of protrusions. The activation hub is arranged to: for a free-wheel mode, rotate the one of the first or second inner hubs in a first rotational direction, with respect to the other of the first or second inner hubs, such that the wedge plate is free of contact with the outer race; and for a locking mode, rotate the one of the first or second inner hubs in a second rotational direction, opposite the first rotational direction, with respect to the other of the first or second inner hubs, to non-rotatably connect the wedge plate with the outer race and the first and second inner hubs.

According to aspects illustrated herein, there is provided a one-way wedge clutch, including: an outer race; a first inner hub including a plurality of radially outwardly extending ramps; a second inner hub including a plurality of radially outwardly extending protrusions; a wedge plate, radially located between the outer race and the first and second inner hubs and including a plurality of radially inwardly extending ramps; and an axially displaceable activation hub engaged with the first and second inner hubs and arranged to rotate the first inner hub in a first rotational direction with respect to the second inner hub such that: for rotation of the first and second inner hubs with respect to the outer race in the first rotational direction, the pluralities of radially inwardly and outwardly extending ramps engage and displace the wedge plate radially outward to non-rotationally connect the outer race and the first and second inner hubs; and for rotation of the first and second inner hubs with respect to the outer race in a second rotational direction, opposite the first rotational direction, the plurality of radially outwardly extending protrusions engage and rotate the wedge plate such that the outer race is rotatable with respect to the first and second inner hubs.

DETAILED DESCRIPTION

FIG. 1Ais a perspective view of cylindrical coordinate system80demonstrating spatial terminology used in the present application. The present invention is at least partially described within the context of a cylindrical coordinate system. System80has a longitudinal axis81, used as the reference for the directional and spatial terms that follow. The adjectives “axial,” “radial,” and “circumferential” are with respect to an orientation parallel to axis81, radius82(which is orthogonal to axis81), and circumference83, respectively. The adjectives “axial,” “radial” and “circumferential” also are regarding orientation parallel to respective planes. To clarify the disposition of the various planes, objects84,85, and86are used. Surface87of object84forms an axial plane. That is, axis81forms a line along the surface. Surface88of object85forms a radial plane. That is, radius82forms a line along the surface. Surface89of object86forms a circumferential plane. That is, circumference83forms a line along the surface. As a further example, axial movement or disposition is parallel to axis81, radial movement or disposition is parallel to radius82, and circumferential movement or disposition is parallel to circumference83. Rotation is with respect to axis81.

The adverbs “axially,” “radially,” and “circumferentially” are with respect to an orientation parallel to axis81, radius82, or circumference83, respectively. The adverbs “axially,” “radially,” and “circumferentially” also are regarding orientation parallel to respective planes.

FIG. 1Bis a perspective view of object90in cylindrical coordinate system80ofFIG. 1Ademonstrating spatial terminology used in the present application. Cylindrical object90is representative of a cylindrical object in a cylindrical coordinate system and is not intended to limit the present invention in any manner. Object90includes axial surface91, radial surface92, and circumferential surface93. Surface91is part of an axial plane, surface92is part of a radial plane, and surface93is a circumferential surface.

FIG. 2is an exploded perspective view of bi-directional wedge clutch100with a split inner hub.

FIG. 3is a schematic block diagram of a bi-directional clutch100with split inner hubs.

FIG. 4is a partial front view of bi-directional wedge clutch100with a split inner hub in free-wheel mode.

FIG. 5is a partial front view of clutch100in a locking mode. The following should be viewed in light ofFIGS. 2 through 5. Bi-directional clutch100includes outer race102, inner hubs104and106, and wedge plate108, radially located between the outer race and inner hubs104and106. Clutch100includes axially displaceable activation hub110, engaged with inner hubs104and106and arranged to rotate at least one of inner hubs104and106with respect to the other of inner hubs104and106to transition between free-wheel and locking modes. For example, hub110is axially displaceable to rotate inner hub104in direction RD1with respect to inner hub106for the free-wheel mode (outer race102independently rotatable with respect to inner hubs104and106) and hub110is axially displaceable to rotate inner hub104in direction RD2with respect to inner hub106for the locking mode (non-rotatably connecting outer race102to inner hubs104and106). In the locking mode, outer race102is non-rotatably connected to inner hubs104and106for relative rotation between outer race102and inner hubs104and106in both of directions RD1and RD2.

In an example embodiment, axially displaceable activation hub110is engaged with inner hubs104and106and is arranged to rotate inner hubs104and106in opposite rotational directions RD1and RD2, respectively, for the free-wheel mode; and to rotate inner hubs104and106in directions RD2and RD1, respectively, for the locking mode. Unless stated otherwise, the following discussion is directed to an embodiment in which only inner hub104is rotated by hub110; however, it should be understood that the discussion is applicable to embodiments in which only inner hub106is rotated by hub110or in which hubs104and106are each rotated by hub110.

In an example embodiment, clutch100includes actuator111for axially displacing activation hub110. Any actuator known in the art can be used for actuator111, including, but not limited to, a screw, electric actuator, pneumatic actuator, or hydraulic actuator.

For clutch100, outer race102can be connected to an input source while inner hub104is an output, or outer race102can be an output when hub104is connected to an input source. The preceding configurations enable torque transmission in either rotational direction in the locking mode.

In an example embodiment, wedge plate108is tensioned radially inward to resist radially outward displacement. For free-wheel mode, activation hub110is displaced in axial direction AD2causing inner hub104to rotate in rotational direction RD1. In an example embodiment, inner circumferential surface112of outer race102is free of contact with outer circumferential surface114of wedge plate108in free-wheel mode, enabling clutch100to operate with zero drag in free-wheel mode

In an example embodiment, wedge plate108includes locking segments116and resilient segments118. Each circumferentially resilient segment118is connected to and circumferentially disposed between a respective pair of locking segments116. In an example embodiment, inner hub104and106are arranged to urge wedge plate108radially outward to transition from the free-wheel mode to the locking mode. The outward displacement of plate108increases respective circumferential distances between the respective pairs of locking segments116and causes outer circumference114of wedge plate108to displace radially outward to contact inner circumferential surface112of outer race102. When activation hub110is sufficiently displaced in axial direction AD1, clutch100is in locking mode and wedge plate108and hubs104and106are non-rotatably connected to outer race102.

In an example embodiment, inner hub104includes slots138which circumferentially bend, or shift, in the axial direction. That is, as slot138progresses in the axial direction, for example, axial direction AD1, the circumferential position of the slot shifts in circumferential direction CM2. Inner hub106includes axially aligned slots140. As further described below, slots138are used to rotate inner hub104.

In an example embodiment, activation hub110includes protrusions150, which circumferentially bend, or shift, in the axial direction, and protrusions152. Protrusions150and152are engaged with slots138and140, respectively. For free-wheel mode, activation hub110displaces in direction AD2, such that the displacement of protrusions150through slots138, rotates hub104in direction RD1such that outer race102is rotatable with respect to inner hubs104and106. For locking mode, activation hub110axially displaces in direction AD1, opposite axial direction AD2, such that the displacement of protrusions150through slots138rotates hub104in direction RD2to non-rotatably connect wedge plate108with outer race102and inner hubs104and106.

In an example embodiment, each segment116includes portion142and144forming inner circumferential surface120of the segment. Portions142and144taper radially inward in rotational directions RD2and RD1, respectively. Ramps104A and106A, in particular, surfaces130and132, respectively, contact portions142and144. For example, to initiate locking mode while hubs104and106are rotating in direction RD2relative to the outer race, hub104rotates in direction RD2, and ramps104A begin to slide along portions142in direction RD2, forcing plate108radially outward to non-rotatably connect to race102. For example, to initiate locking mode while hubs104and106are rotating in direction RD1relative to the outer race, hub104rotates in direction RD2, and ramps104A contact portions142and rotate the wedge plate in direction RD2such that portions144contact and slide along ramps106A, forcing plate108radially outward to non-rotatably connect to race102.

FIG. 6is a partial cross-sectional view of bi-directional clutch100ofFIG. 2with locking ring146. The following should be viewed in light ofFIGS. 2 through 6. In an example embodiment, clutch100includes axially displaceable locking ring146to engage inner hubs104and106to rotationally lock inner hubs104and106in the locking mode. In an example embodiment, locking ring146includes axial wedges148protruding in axial direction AD1. Actuator154displaces locking ring146in axial direction AD1to insert axial wedges148between ramps104A and106A of inner hubs104and106, respectively, to rotationally lock the inner hubs. When locking ring146is fully engaged, hubs104and106are rotationally locked. When locking ring146is fully engaged with inner hubs104and106, clutch100is in a locked position and clutch100operates with zero lash.

To return to free-wheel mode, actuator154is displaced in direction AD2to disengage locking ring146from hubs104and106. Once the locking ring is disengaged, inner hub106rotates, for example, in direction RD2as activation hub110is axially displaced in direction AD2. This enables wedge plate108to retract radially inward, thereby removing contact with outer race102. Once wedge plate108breaks contact with outer race102, clutch100is in free-wheel mode.

In an example embodiment, activation hub110is axially locked with actuator111in the locking mode after activation hub110is displaced a sufficient distance in direction AD1. This keeps the clutch locked with zero lash.

In an example embodiment, when activation hub110is fully displaced in axial direction AD1by actuator111, that is, clutch100is in the locking mode, actuator111is displaced in axial direction AD2such that inner hubs104and106rotate relative to each other until radially disposed sides156and158of ramps104A and106A, respectively, contact each other. In this configuration, clutch100is in locking mode for one of directions RD1or RD2until torque is removed, after which clutch100free-wheels.

In an example embodiment, inner circumferential surface112of outer race102and outer circumferential surface114of wedge plate108have respective chamfered edges. The use of chamfered edges on surfaces112and114provides a smooth transition between free-wheel mode and locking mode. In addition, chamfered edges provide greater surface area when outer circumferential surface114of wedge plate108contacts inner circumferential surface112of outer race102.

In an example embodiment, clutch100is used to provide torque to an accessory drive system. For instance, in locking mode, clutch100transfers torque to a planetary gear that helps start an engine. If clutch100is disengaged, in free-wheel mode, the planetary gear is not in use.

FIG. 7is an exploded view of an activation hub with slots and inner hubs with protrusions. In an example embodiment, inner hub104includes slots138, inner hub106includes protrusions152and activation hub110includes protrusions150and slots140. The discussion of clutch100forFIGS. 2 through 6is applicable to the embodiment of clutch100shown inFIG. 7. It should be understood that other combinations (not shown) are possible, such as: inner hub104having protrusions150, hub110having protrusions152and slots138, and inner hub106having slots140; and inner hub104having protrusions150, hub110having slots138and140, and inner hub106having protrusions152. The discussion of clutch100forFIGS. 2 through 6is applicable to the preceding embodiments of clutch100.

FIG. 8is a partial front view of one-way clutch100with a split inner hub. In an example embodiment, clutch100is a one-way, rather than a bi-directional clutch. In a one-way clutch embodiment, one of ramps104A or106A is replaced by blocking elements160. InFIG. 8, ramps106A are replaced by elements160; however, it should be understood that ramps104A can be replaced by elements160. One-way clutch100operates as follows. For the locking mode (relative rotation of the inner hubs with respect to the outer race in direction RD2), hub104is displaced in direction RD2, ramps104A engage the wedge plate, and the wedge plate begins to rotate with the outer race causing the ramps to ride up portions142to displace the wedge plate radially outward to non-rotatably connect the outer race with the inner hubs. For the free-wheel mode (relative rotation of the inner hubs with respect to the outer race in direction RD1), blocking elements160rotate wedge plate116in direction RD1without causing the wedge plate to expand radially outward or causing portions142to ride up ramps104A.