DIFFERENTIAL

FIELD

[0001] The present disclosure relates generally to electronically actuated locking differentials and, more particularly, to stator anti-rotation features for an electronically actuated locking differential

BACKGROUND

[0002] In automotive applications, an electronically actuated locking differential of the related art may be actuated electronically and is designed for forward -wheel- drive (FWD), rear-wheel-drive (RWD), all-wheel-drive (AWD), and four-wheel-drive (4WD) vehicles to allow the differential to be locked or unlocked when it is so desired. The driver can lock the front and/or rear wheels by manually activating a switch or button mounted to a dash or console of the vehicle However, as vehicles and associated systems become more complex, vehicle component packaging also becomes more challenging. Accordingly, it is desirable to reduce parts and provide a more compact electronically actuated locking differential.

[0003] The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure. SUMMARY

[0004] Sn one example aspect, an electronically actuated locking differential configured to be disposed at least partially within an axle housing having a first half and a second half is provided. The electronically actuated locking differential includes a gear case having opposite first and second ends, a differential gear set disposed in the gear case, a lock plate disposed at the gear case first end and configured to selectively engage the differential gear set, and an electronic actuator disposed at the gear case and including a stator. The stator includes a stator housing, an electromagnetic coil disposed at least partially within the stator housing, and an anti- rotation tab coupled to the stator housing. At least a portion of the anti-rotation tab extends radially outward from an outer diameter of the stator housing. The anti - rotation tab is configured to facilitate preventing rotation of the stator by being disposed in one of (i) a slot formed in the axle housing first half, and (ii) a slot formed in a bearing cap disposed adjacent the stator housing. The electronic actuator is operable between an unlocked first mode where the lock plate does not lockingly engage the differential gear set, and a locked second mode when the stator is energized where the lock plate lockingly engages the differential gear set.

BRIEF DESCRIPTION OF THE DRAWINGS

[0005] The present disclosure will become more fully understood from the detailed description and the accompanying drawings, wherein:

[0006] FIG. 1 is a sectional view of an electronically actuated locking differential having a stator with anti -rotation features constructed in accordance to one example of the present disclosure;

[0007] FIG. 2 is an exploded view of the example electronically actuated locking differential shown in FIG. 1 ; [0008] FIG. 3 is a side view of the stator with anti-rotation features shown in FIG. 1 constructed in accordance to one example of the present disclosure;

[0009] FIG. 4 is a cross-sectional view of the electronically actuated locking differential shown in FIG. 1 installed within an example portion of a vehicle;

[0010] FIG. 5 is a sectional view of another electronically actuated locking differential having a stator with anti-rotation features constructed in accordance to one example of the present disclosure;

[0011] FIG. 6 is an exploded view of the example electronically actuated locking differential shown in FIG. 5;

[0012] FIG. 7 is a side view of a portion of the electronically actuated locking differential shown in FIG. 5 installed within an example portion of a vehicle; and

[0013] FIG. 8 is a side view of the stator with anti -rotation features shown in FIG. 5 constructed in accordance to one example of the present disclosure.

DETAILED DESCRIPTION

[0014] Described herein are systems and methods for providing vehicle axles with anti-rotation features. The stator assembly of an electronically actuated locking differential is provided with anti -rotation tabs that can be disposed in a slot between two axle halves to facilitate preventing stator assembly rotation. Such a system effectively arrests stator rotational degrees of freedom without additional anti -rotation components.

[0015] With initial reference to FIGS. 1 and 2, an electronically actuated locking differential is generally indicated at 10. In the example embodiment, the electronically actuated locking differential 10 generally includes a gear case 12 formed by coupling (e.g., bolting) a hub portion 14 and housing portion 16. Torque input to the differential is typically by an input ring gear (not shown), which may be attached to a flange 18 of the gear case 12. Each of the hub portion 14 and the housing portion 16 of the gear case 12 may be mounted to a bearing set (not shown) to provide rotational support for the differential 10 relative to an outer housing or carrier (not shown).

[0016] The gear case 12 defines a gear chamber 20, which generally supports a differential gear set including a pair of input pinion gears 22 rotatably mounted on a pinion shaft 24, which is secured relative to the gear case 12 by any suitable mechanism. The pinion gears 22 are meshingly engaged with a respective pair of side gears 26, 28. The side gears 26, 28 define respective sets of internal, straight splines 30 that are adapted to be in splined engagement with mating external splines on a respective pair of left and right axle shafts (not shown).

[0017] The electronically actuated locking differential 10 further includes a rotation prevention mechanism 32 configured to selectively prevent relative rotation of the left and right axle shafts. The rotation prevention mechanism 32 is disposed within gear case 12 and generally includes a lock plate 34 opera bly associated with side gear 28 (the first output gear).

[0018] The lock plate 34 is spaced apart from the side gear 28 and is slidable along the outer surface of side gear 28. The lock plate 34 can be biased toward a non-actuated, unlocked mode by a biasing mechanism (not shown) such as a wave spring. The lock plate 34 can include a plurality of radially spaced dog teeth (not shown) configured to selectively engage the side gear 28, as described herein in more detail. The lock plate 34 can include an end face 36 and a plurality of circumferential protrusions 38 configured to be received within slots 40 formed within an inner wall of the gear case 12 to prevent relative rotation between the lock plate 34 and the gear case 12.

[0019] An electronic actuator 50 is disposed primarily external to the gear case 12 in a location opposite the flange 18 at a bell end of the gear case 12 and adjacent to side gear 26. The electronic actuator 50 generally includes push rods 52 operably coupled to lock plate 34, a ramp plate 54, needle roller bearings 56, a bearing race 58, and a stator 62.

[0020] With additional reference to FIG. 3, in the example embodiment, stator 62 includes a housing 64 configured to receive an electromagnetic coil 66. The coil 66 is configured to be energized via electrical wires 68 associated with a grommet 70, pins 72, and a connector 74 (see FIG. 3). The coil receives direct current (DC) from a power source (not shown) such as a vehicle battery. The push rods 52 extend outwardly from the ramp plate 54 and are positioned to contact the lock plate end face 36. In an alternative embodiment, push rods 52 can be coupled to lock plate 34 and extend outwardly toward ramp plate 54.

[0021] That stator 62 is generally annular and spaced apart from the ramp plate 54 12 by a gap 76 (FSG. 1 ). In the example embodiment, at least a portion of the ramp plate 54 is fabricated from a magnetic material such that stator 62 is configured to interact therewith, thus operating as an armature, and providing a more compact arrangement of differential 10 than previously known systems.

[0022] With continued reference to FIG. 3, in the example embodiment, stator 62 includes an anti-rotation tab 80 extending from the stator housing 64. The anti-rotation tab 80 is coupled to an end surface 82 of the stator housing 64, for example, via welding. However, it will be appreciated that anti-rotation tab 80 may be formed integrally with stator housing 64. [0023] As illustrated, the anti-rotation tab 80 extends generally radially outward from an outer diameter of the stator housing 64. In this way, anti-rotation tab 80 extends in a plane generally parallel to a plane of the stator 62. In the example embodiment, the anti-rotation tab 80 facilitates preventing rotation of the stator 62, for example, to provide drag torque on the ramp plate when locking actuated, and to improve fatigue life of the wires 68.

[0024] With additional reference to FIG. 4, the locking differential 10 is disposed within an axle housing 84 comprising a first half 86 and a second half 88. A slot 90 is formed (e.g., machined) into the inner surface of the axle housing first half 86 proximate an interface 92 between the two halves 86, 88. As shown, the slot 90 is sized and shaped to receive at least a portion of the anti-rotation tab 80. In this way, the anti-rotation tab 80 is prevented from counter clockwise rotation (as viewed in FIG. 4) by the axle housing first half 86, and prevented from opposite clockwise rotation by the mating face 94 of the axle housing second half 88. As such, the anti -rotation tab 80 does not require additional components (e.g., separate anti-rotation brackets) to prevent rotation or substantial rotation of the stator 62.

[0025] Turning now to FIGS. 5-8, electronically actuated locking differential 10 is illustrated with another example embodiment of stator 62, which includes an antirotation tab 100 instead of anti-rotation tab 80. Like parts are identified by like reference numerals. In the example embodiment, the anti-rotation tab 100 is coupled to the end surface 82 of the stator housing 64, for example, via welding. However, it will be appreciated that anti-rotation tab 100 may be formed integrally with stator housing 64.

[0026] As illustrated in FIGS. 6 and 7, in the example embodiment, the antirotation tab 100 extends generally radially outward from an outer diameter of the stator housing 64, and subsequently turns 90° or approximately 90° and extends perpendicular to or generally perpendicular to the stator 62. In this way, anti -rotation tab 100 has a first portion 104 extending in a plane parallel to or generally parallel to a plane of the stator 62, and a second portion 106 extending in a plane perpendicular to or generally perpendicular to a plane of the stator 62. In the example embodiment, the anti-rotation tab 100 facilitates preventing rotation or substantial rotation of the stator 62, for example, to provide drag torque on the ramp plate when locking actuated, and to improve fatigue life of the wires 68.

[0027] As shown in FIG. 8, the locking differential 10 is disposed within the vehicle such that the stator housing 64 is disposed adjacent to a bearing cap 108. In the example embodiment, the bearing cap 108 is pressed onto the gear case 12 and configured to house a taper roller bearing (not shown). A slot 1 10 is formed (e.g., machined) in the bearing cap 108 such that the slot 110 is defined at least partially by opposed walls 112, 1 14. As illustrated, the anti -rotation tab 100 is received within the slot 1 10 between the opposed walls 112, 1 14. In this way, the anti-rotation tab 100 is prevented from counter clockwise rotation (as viewed in FIG. 8) by the slot wall 112, and prevented from opposite clockwise rotation by the slot wall 1 14. As such, the anti- rotation tab 100 does not require additional anti-rotation brackets to prevent rotation of the stator 62.

[0028] Moreover, it will be appreciated that the stators 62 described herein may be utilized in various other systems such as, for example, those described in commonly owned U.S. Pat. No. 9,556,945, the entire contents of which are incorporated herein by reference thereto.

[0029] During normal, straight-ahead operation of a vehicle within which the differential 10 is employed, no differentiation occurs between the left and right axle shaft or side gears 26, 28. Therefore, the pinion gears 22 do not rotate relative to the pinion shaft 24. As a result, the gear case 12, pinion gears 22, and side gears 26, 28 all rotate about an axis of rotation as if the gear case 12, pinion gears 22, and side gears 26, 28 are a solid unit.

[0030] When direct current (DC) power is supplied to the electromagnetic coil

60, magnetic energy is generated within the stator 62, which creates an attractive force between the stator 62 and the ramp plate 54, thereby causing the ramp plate 54 to move toward the stator 62. This in turn causes the push rods 52 to move rightward (as shown in FIG. 1), which translates the lock plate 34 toward and into locking engagement with side gear 28 as it compresses the biasing mechanism. Lock plate teeth meshingly engage side gear teeth until lock plate 34 exerts a required retarding torque on the side gear 28, locking it to the differential case 12 and thus locking the left and right axle shafts independent of driveline rotation.

[0031] The differential 10 may be controlled manually, wherein a driver of the vehicle manually selects“locked” mode (rather than“unlocked” mode) to operate the differential 10. For example, when, say the vehicle is at rest, the driver simply manually activates a switch or button (not shown), such as a simple momentary-type “on/ofF toggle or rocker switch or push button, mounted to a dash or console (not shown) of the vehicle. In this way, an electric circuit (not shown) is dosed, thereby turning on current in the circuit and a lamp (not shown) located in or near the toggle switch or push button to indicate to the driver that the differential is actuated. Current flows in the circuit and ultimately to the electromagnetic coil 60 of the differential 10. The differential 10 then operates in the“locked” mode (Le., when the vehide is in first gear or reverse). In this way, the first output gear 28 is locked relative to the gear case 12, preventing any further differentiation between the first output gear 28 and gear case 12.

[0032] Described herein are systems and methods for providing vehicle axles with anti-rotation features. The stator assembly of an electronically actuated locking differential is provided with anti-rotation tabs that can be disposed in a slot between two axle halves to facilitate preventing stator assembly rotation. Such systems effectively arrest stator rotational degrees of freedom without additional anti-rotation components. Moreover, the systems can reduce assembly time (no additional components), simplify manufacturing (e.g., no cutting or welding), and reduce overall costs.

[0033] The foregoing description of the examples has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular example are generally not limited to that particular example, but, where applicable, are interchangeable and can be used in a selected example, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.