Patent Application
20180187725
The present invention relates generally to a wedge clutch, and, more specifically, to a wedge clutch having a plurality of circumferentially aligned wedge plate segments partially contained within a cage and including a circumferentially continuous resilient element arranged to urge the wedge plate segments into contact with a hub for the clutch.
Known wedge plate clutches, for example for use with all-wheel drive applications, typically use one or more one-piece, scalloped, single-split wedge plates to connect and disconnect two shafts. A single-split wedge plate results in unequal locking pressure in a locked mode non-rotatably connecting the two shafts. As a result of the unequal locking pressure, the torque-bearing capacity and durability of the clutch are compromised. Further, when the hub of the clutch is mounted to a rotating shaft and the wedge plate is mounted on the outer tapered surface of the hub, in the free-wheel mode (the shafts connected to the clutch are to rotate with respect to each other), centrifugal forces from the rotation of the hub can force the wedge plate to move radially outward at high speed to engage the outer ring of the clutch, resulting in an unintentional shift to the locked mode.
To address the problem of unequal radial movement of the wedge plate, it is known to replace the one-piece wedge plate in a wedge clutch with a plurality of circumferentially aligned wedge plate segments. The wedge segments are arranged around a tapered hub and are positioned with a retaining ring, which also functions as a spring to enable the wedge segments radial movement. However, the retaining ring, like the one-piece wedge plates, has a single-split and therefore does not allow equal radial movement of the wedge segments. The single-split design also limits the ability of the retaining ring to prevent undesired radially outward displacement of the wedge plate segments (due to rotation of the hub) during the free-wheel mode.
According to aspects illustrated herein, there is provided a wedge clutch, including: an axis of rotation; a hub; an outer ring located radially outward of the hub; a cage radially disposed between the hub and the outer ring; a plurality of circumferentially aligned wedge plate segments radially disposed between the hub and the outer ring; and a circumferentially continuous resilient element engaged with the cage and the plurality of circumferentially aligned wedge plate segments, and urging the plurality of circumferentially aligned wedge plate segments radially inward.
According to aspects illustrated herein, there is provided a wedge clutch, including: an axis of rotation; a hub including a radially outermost surface sloping radially outward in a first axial direction; an outer ring located radially outward of the hub; a plurality of circumferentially aligned wedge plate segments radially disposed between the hub and the outer ring and in contact with the hub; a cage radially disposed between the hub and the outer ring and including a plurality of retention tabs, each retention tab, included in the plurality of retention tabs, overlapping a respective pair of circumferentially aligned wedge plate segments included in the plurality of circumferentially aligned wedge plate segments; and a resilient element engaged with the cage and the plurality of circumferentially aligned wedge plate segments, and urging the plurality of circumferentially aligned wedge plate segments radially inward. For a locked mode: the hub is axially displaceable in a second axial direction, opposite the first axial direction, to displace the plurality of circumferentially aligned wedge plate segments radially outward into contact with the outer ring; and the plurality of circumferentially aligned wedge plate segments are arranged to non-rotatably connect to the hub and the outer ring. For a free-wheel mode: the hub is axially displaceable in the first axial direction; the resilient element is arranged to displace the plurality of circumferentially aligned wedge plate segments radially inward; and the plurality of circumferentially aligned wedge plate segments is rotatable with respect to the outer ring.
According to aspects illustrated herein, there is provided a method of operating a wedge clutch including a hub, an outer ring, a circumferentially continuous resilient element, a plurality of wedge plate segments radially located between the hub and the outer ring, and a cage radially located between the hub and the outer ring, the method including: engaging, with the circumferentially continuous resilient element, the cage and the plurality of circumferentially aligned wedge plate segments; urging, with the circumferentially continuous resilient element, the plurality of circumferentially aligned wedge plate segments radially inward; contacting the hub with the plurality of circumferentially aligned wedge plate segments; for a locked mode, displacing the hub in a first axial direction, displacing, with the hub, the plurality of circumferentially aligned wedge plate segments radially outward into contact with the outer ring, and non-rotatably connecting the plurality of circumferentially aligned wedge plate segments with the hub and the outer ring; and for a free-wheel mode, displacing the hub in a second axial direction opposite the first axial direction, displacing, with the circumferentially continuous resilient element, the plurality of circumferentially aligned wedge plate segments radially inward, and rotating the plurality of circumferentially aligned wedge plate with respect to the outer ring.
Various embodiments are disclosed, by way of example only, with reference to the accompanying schematic drawings in which corresponding reference symbols indicate corresponding parts, in which:
At the outset, it should be appreciated that like drawing numbers on different drawing views identify identical, or functionally similar, structural elements of the disclosure. It is to be understood that the disclosure as claimed is not limited to the disclosed aspects.
Furthermore, it is understood that this disclosure is not limited to the particular methodology, materials and modifications described and as such may, of course, vary. It is also understood that the terminology used herein is for the purpose of describing particular aspects only, and is not intended to limit the scope of the present disclosure.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which this disclosure belongs. It should be understood that any methods, devices or materials similar or equivalent to those described herein can be used in the practice or testing of the disclosure.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which this present disclosure belongs. It should be appreciated that the term “substantially” is synonymous with terms such as “nearly”, “very nearly”, “about”, “approximately”, “around”, “bordering on”, “close to”, “essentially”, “in the neighborhood of”, “in the vicinity of”, etc., and such terms may be used interchangeably as appearing in the specification and claims. It should be appreciated that the term “proximate” is synonymous with terms such as “nearby”, “close”, “adjacent”, “neighboring”, “immediate”, “adjoining”, etc., and such terms may be used interchangeably as appearing in the specification and claims.
To clarify the spatial terminology, objects 12, 13, and 14 are used. As an example, an axial surface, such as surface 15A of object 12, is formed by a plane co-planar with axis 11. However, any planar surface parallel to axis 11 is an axial surface. For example, surface 15B, parallel to axis 11 also is an axial surface. An axial edge is formed by an edge, such as edge 15C, parallel to axis 11. A radial surface, such as surface 16A of object 13, is formed by a plane orthogonal to axis 11 and co-planar with a radius, for example, radius 17A. A radial edge is co-linear with a radius of axis 11. For example, edge 16B is co-linear with radius 17B. Surface 18 of object 14 forms a circumferential, or cylindrical, surface. For example, circumference 19, defined by radius 20, passes through surface 18.
Axial movement is in direction axial direction AD1 or AD2. Radial movement is in radial direction RD1 or RD2. Circumferential, or rotational, movement is in circumferential direction CD1 or CD2. The adverbs “axially,” “radially,” and “circumferentially” refer to movement or orientation parallel to axis 11, orthogonal to axis 11, and about axis 11, respectively. For example, an axially disposed surface or edge extends in direction AD1, a radially disposed surface or edge extends in direction RD1, and a circumferentially disposed surface or edge extends in direction CD1.
Cage 102 includes retention tabs 130 extending from body portion 126 in axial direction AD2. In
In an example embodiment, each segment 108 includes at least one notch extending radially outward from radially innermost surface 112. In an example embodiment, each segment 108 includes notch 132 and notch 134. A respective retention tab 130 is disposed in respective notches 132 and 134 for circumferentially adjacent segments 108. For example, tab 130A is disposed in notch 134 for segment 108A and in notch 132 for segment 108B.
In the example of
As hub 102 displaces in direction AD1, surfaces 112 slide down surface 114 and resilient element, reacting to radially fixed flange 128, displaces wedge plate segments 108 radially inward in radial direction RD2 to maintain contact between hub 102 (surface 114) and wedge plate segments 108 (surfaces 112). As segments 108 retract in direction RD2, outer surfaces 148 of segments 108 break contact with inner surface 150 of ring 104 and segments 108 (along with hub 102) are rotatable with respect to outer ring 104. By “non-rotatably connected” elements, we mean that: the elements are connected so that whenever one of the elements rotates, all the elements rotate; and relative rotation between the elements is not possible. Radial and/or axial movement of non-rotatably connected elements with respect to each other is possible, but not required.
As hub 102 displaces in axial direction AD1: resilient element 110 unwinds, expands, or decompresses, in radial direction RD2; and protrusions 138 slide through through-bores 136 in direction RD2. As noted above, width 139 of through-bores 138 is only slightly larger than diameter 140 of protrusions 138. As a result, there is nominal circumferential movement of segments 108 with respect to cage 106 as segments 108 displace radially inward. In an example embodiment, edges 151 of circumferentially adjacent segments—are in contact in the free-wheel mode.
As segments 108 are displaced radially outward in direction RD1: resilient element 110 is compressed in radial direction RD1 between shoulders 118 and cage 106, for example, between shoulders 118 and flange 128; and protrusions 138 slide through through-bores 136 in direction RD1. As in the example embodiment noted above, width 139 of through-bores 138 is only slightly larger than diameter 140 of protrusions 138, and there is nominal circumferential movement of segments 108, with respect to cage 106, as segments 108 displace radially outward. Therefore, a consistent circumferential orientation and spacing of segments 108 is maintained. For example, circumferential spacing 154 between segments 108 is evenly maintained between all the adjacent segments 108.
The following provides further detail regarding wedge clutch 100. In an example embodiment, hub 102 includes spline teeth 152 arranged to non-rotatably connect to a shaft (not shown). Ring 104 is arranged to non-rotatably connect to a second shaft. Thus, clutch 100 is usable to non-rotatably connect the shafts in the locked mode and enable relative rotation between the shafts in the free-wheel mode. In an example embodiment, surfaces 148 include chamfered surfaces 158 and surface 150 includes groove 160 with chamfered surfaces 162.
Although clutch 100 is shown with a particular number of wedge plate segments 108, it should be understood that clutch 100 is not limited to the number of segments 108 shown and that other numbers of segments 108 are possible. Although clutch 100 is shown with a particular axial orientation, it should be understood that other axial orientations are possible. For example, flange 128 could extend in direction AD1 and protrusions 138 could extend in direction AD2.
Advantageously, clutch 100 solves the problem noted above of unequal locking pressure in a locked mode and unequal radial movement of the wedge segments. In particular, resilient element 110 applies an equal force F to each segment 108, ensuring that segments 108 displace radially inward and radially outward in unison. For example, radius 145 changes uniformly for all of segments 108 during transitions between the locked and free-wheel mode, and radius 144 is uniform for each of segments 108 in the locked mode. Thus, equal locking pressure is applied by each of segments 108 during the locked mode. Further, resilient element 110 provides preloading force F to prevent segments 108 from displacing radially inward during the free-wheel mode, preventing an undesired shift from the free-wheel mode to the locked mode.
It will be appreciated that various of the above-disclosed and other features and functions, or alternatives thereof, may be desirably combined into many other different systems or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the following claims.
