Locking arrangement for differential case

Abstract

An electronically controlled differential locking system includes a moveable lock plate within a differential housing that is actuated by an armature. The lock plate includes integral legs that extend through the differential housing. The lock plate is rotationally fixed relative to the differential housing by the legs. The legs extend out of the differential housing to engage with the armature, which is operated using an electromagnet. The differential housing is configured to inhibit tilting of the lock plate.

Description

LOCKING ARRANGEMENT FOR DIFFERENTIAL CASECROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This paper is being filed as a PCT application claiming the benefit of IN Application No. 202311060512, filed September 08, 2023, the disclosure of which are hereby incorporated herein by reference in its entirety.BACKGROUND

[0002] Traction modifying locking differentials typically include a differential case defining a gear chamber, and disposed therein, a differential gear set including at least one input pinion gear and a pair of output side gears. Typically, such a "locking differential" includes some sort of locking mechanism to prevent rotation of one of the side gears relative to the differential case, the engagement of the locking mechanism being initiated by some sort of actuator. Transmitting an appropriate input signal to an electromagnetic coil results in a locking member engaging a mating portion associated with the differential side gear disposed. The electromagnetic coil is held by a stator disposed external of the differential case.SUMMARY

[0003] The present disclosure is directed to an electronically controlled locking differential system.

[0004] Aspects of the present disclosure including a locking arrangement for a locking differential system including a lock plate that is slidable along a rotational axis of a differential housing. The lock plate includes monolithically formed legs that operationally engage with an armature. Movement of the armature, which is controlled by an electromagnet, controls movement of the lock plate between locking and non-locking positions.

[0005] Aspects of the present disclosure include a differential system including a differential housing and a locking arrangement. The locking arrangement includes a lock plate disposed within the differential housing and an armature disposed external of the differential housing. Legs of the lock plate extend through the differential housing to operationally engage the armature.

[0006] The lock plate carries a gear set configured to selectively mesh with a locking gear of a differential gear set within the differential housing. When meshed, the lock plate holds the locking gear rotationally stationary relative to the differential housing. When separated, the locking gear (and rest of the differential gear set) can rotate relative to the differential housing. In some examples, the gear set faces in an opposite direction to the legs of the lock plate. In other examples, the gear set faces generally transverse to the legs.

[0007] A variety of additional inventive aspects will be set forth in the description that follows. The inventive aspects can relate to individual features and to combinations of features. It is to be understood that both the forgoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the broad inventive concepts upon which the embodiments disclosed herein are based.BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The accompanying drawings, which are incorporated in and constitute a part of the description, illustrate several aspects of the present disclosure. A brief description of the drawings is as follows:

[0009] FIG. l is a schematic view of a vehicle with a locking differential system according to an example of the present disclosure;

[0010] FIG. 2 is a perspective view of a first example differential housing and locking arrangement suitable for use in the locking differential system of FIG. 1;

[0011] FIG. 3 is another perspective view of the differential housing and locking arrangement of FIG. 2;

[0012] FIG. 4 is a cross-sectional view of the differential housing and locking arrangement of FIG. 2;

[0013] FIG. 5 is an enlarged view of a portion of FIG. 4 showing an armature of the locking arrangement in a first position and a lock plate of the locking arrangement in a nonlocking position;

[0014] FIG. 6 shows the armature of FIG. 5 in the second position and the lock plate in the locking position;

[0015] FIG. 7 is a first perspective view of an example lock plate suitable for use in the differential case and lock arrangement of FIG. 2;

[0016] FIG. 8 is a second perspective view of the lock plate of FIG. 7;

[0017] FIG. 9 is an end view of the lock plate of FIG. 8;

[0018] FIG. 10 is a cross-sectional view of the differential housing of FIG. 2 with the lock arrangement and differential gear set removed for ease in viewing;

[0019] FIG. 11 is a perspective view of a cross-section taken of a second example differential housing and locking arrangement suitable for use in the locking differential system of FIG. 1;

[0020] FIG. 12 is a perspective view of an example locking gear suitable for use within the differential housing of FIG. 11; and

[0021] FIG. 13 is a perspective view of an example lock plate suitable for use within the differential housing of FIG. 11.DETAILED DESCRIPTION

[0022] Reference will now be made in detail to exemplary aspects of the present disclosure that are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.

[0023] The present disclosure relates generally to locking differentials, and more particularly to electronically controlled locking differentials used in vehicle drive axles. As used herein, an electronically controlled locking differential means a differential that changes between an unlocked state and a locked state in response to an electronic signal. In the locked state, both axle shafts connected to the differential rotate together in the same direction and at the same speed. The electronic signal may be automatically produced in response to a vehicle condition, for example, detection of wheel slippage. The electronic signal may also be produced in response to a demand from an operator, for example, an operator may press a button or actuate a switch on a control panel of the vehicle.

[0024] Examples of the present disclosure may allow the differentials to operate at a higher torque than similarly sized existing locking differentials. Further, the status indicator may provide a more satisfactory user experience by providing more detailed and accurate information regarding the operation of the electronically controlled.

[0025] Referring to FIG. 1, a powertrain 5 for a vehicle 70 includes a motor 6, a propeller shaft 7 connected to the motor 6, and an axle assembly 8. The propeller shaft 7 is connected, for example, by gearing (not shown) to rotationally drive the axle shafts 13, 13’ inside the axle housing 9. The axle assembly 8 includes the axle housing 9, a locking differential assembly 10 supported in axle housing 9, and the axle shafts 13, 13’ respectively connected to first and second drive wheels 98 and 98’. The axle housing 9 may be part of a transaxle. A gearset 97disposed within a differential housing 12 transfers rotational power from the differential housing 12 to the axle shafts 13, 13’ and selectably allows relative rotation between the axle shafts 13 and 13’.

[0026] The locking differential assembly 10 of the present disclosure may be included in rear axles, front axles, transaxles, transfer cases, or in any vehicle powertrain. Moreover, it is contemplated that the motor 6 can be any motor such as an internal combustion engine, an electric motor, a hybrid-electric motor, or combinations thereof, or any device configured to impart rotational movement onto the propeller shaft.

[0027] The locking differential assembly 10 is controlled by a locking differential system 11 including an electrical switch 17. The electrical switch 17 is configured to selectably close a circuit 23 to provide electrical power to a coil or other electromagnet 142 of the locking differential assembly 10. In certain examples, the electrical switch 17 is a rocker switch. However, other types of switches capable of controlling the flow of power through the coil may be used. The electrical switch 17 may be a low current switch that controls a relay or transistor that directly controls power through the coil 142. In certain implementations, the differential system 11 also includes an electronic status indicator 29. In certain implementations, the differential system 11 includes an electronic driver circuit 25 for powering the electronic status indicator 29 to indicate a status of the locking differential system 11.

[0028] Examples 100, 200 of suitable locking differential arrangements 10 are shown in FIGS. 2-10 and 11-13, respectively. The differential housing 12 of the locking differential arrangement 100, 200 is shown with reference number 102. The differential housing 102 is configured to rotate about a rotation axis R of the housing 102 relative to a stator 140 disposed external of the differential housing 102. The differential housing 102 includes a flange 104 extending radially outwardly from a gear case 106. In some implementations, the flange 104 and gear case 106 are formed from two or more separate pieces fastened together. In other implementations, the flange 104 and gear case 106 are monolithically formed.

[0029] A differential gear set 112 is disposed within the gear case 106. Torque input to the locking differential housing 102 can be provided by an input ring gear (not shown) to the flange 104. The differential housing 102 defines annular hub portions 108 and 110 at which left and right axle shafts 13, 13’ are coupled. A pair of bearing sets (not shown) disposed at the annular hub portions 108, 110 provide rotational support for the rotating differential housing 102 relative to an outer differential housing or "carrier" 9.

[0030] The locking differential arrangement 100, 200 can be operated in a locked mode or an unlocked mode. When operated in the locked mode, one or both axles 13, 13’ are locked against rotation relative to the differential housing 102. When operated in the unlocked mode, the axles 13, 13’ are free to spin relative to the differential housing 102. In some implementations, the locking differential 100, 200 is transitioned between locked and unlocked modes manually by a user. In other implementations, the locking differential 100, 200 is transitioned between locked and unlocked modes automatically (e.g., by a microprocessor of the vehicle controlling switch 17 based on a sensed operational condition of the vehicle).

[0031] Referring now to FIGS. 2-13, the locking differential 100, 200 includes a locking arrangement 118, 218 that can be transitioned between a locking configuration and a nonlocking configuration. When disposed in the locking configuration, the locking arrangement 118, 218 inhibits independent rotation of the side gears 114, 116 of the differential gear set 112 relative to the differential housing 102. When disposed in the non-locking configuration, the side gears 114, 116 are free to spin relative to the differential housing 102. For example, the side gears 114, 116 may be configured to independently rotate about the rotation axis R of the differential housing 102.

[0032] In certain implementations, the locking arrangement 118, 218 interacts with one of the side gears, referred to herein as a locking gear 114, 214, of the differential gear set 112. The locking gear 114, 214 includes engagement members 115, 215 (e.g., gear teeth such as dog teeth, radial teeth, splines, lugs, or other such members) configured to selectively engage the locking arrangement 118, 218. In certain implementations, the locking gear 114, 214 remains axially stationary within the differential housing 102 when the locking arrangement 118, 218 transitions between the locking and non-locking configurations.

[0033] In certain implementations, the locking arrangement 118, 218 includes a lock plate 120, 220 disposed within the differential housing 102. The lock plate 120, 220 is axially movable (e.g., parallel to the rotation axis R) relative to the locking gear 114, 214 between a locking position (e.g., see FIG. 6) and a non-locking position (e.g., see FIG. 5). The lock plate 120, 220 includes one or more legs 132, 232 extending outwardly from a collar 126, 226, respectively. The collar 126, 226 defines a gear set 130, 230 configured to mesh with the locking engagement members 115, 215 of the locking gear 114, 214 when the lock plate 120, 220 is disposed in the locking position. The gear set 130, 230 does not engage (e.g., is spaced from) the engagement members 115, 215 of the locking gear 114, 214 when the lock plate 120,220 is disposed in the non-locking position. For example, as shown in FIG. 6, dog teeth 115 of the locking gear 114 may engage dog teeth 130 of the lock plate 120 in the locking position. FIG. 11 shows radially outward teeth 215 of the locking gear 214 axially spaced from radially inward teeth 230 of the lock plate 220 in the non-locking position. The radially outward teeth 215 are configured to mesh with the radially inward teeth 230 when the lock plate 220 is moved to the non-locking position.

[0034] The legs 132, 232 are circumferentially spaced front each other. In certain implementations, each leg 132, 232 extends from a base end 132a, 232a disposed at the collar 126, 226 to a free end 132b, 232b opposite the collar 126, 226, respectively. In certain implementations, the legs 132, 232 are axially and rotationally stationary relative to the collar 126, 226. In certain implementations, the legs 132, 232 rigidly (i.e., non-deflectably) extend from the collar 126, 226. In certain implementations, the legs 132, 232 (e.g., the base end 132a, 232a of the legs 132, 232) are integral with the collar 126, 226. In certain examples, the legs 132, 232 (e.g., the base end 132a, 232a of the legs 132, 232) are monolithically formed with the collar 126, 226. In the example shown, the lock plate 120, 220 includes eight legs 132, 232. In other examples, however, the lock plate 120, 220 can include a greater or lesser number (e.g., one, three, four, six, ten, etc.) of legs 132, 232.

[0035] In some implementations, the gear set 130 of the lock plate 120 faces in an opposite direction from the legs 132 (e.g., see FIG. 7). In such examples, the engagement members 115 of the locking gear 114 face towards the stator 140. In certain examples, the gear set 130 and engagement members 115 include dog teeth configured to mesh. In other implementations, however, the gear set 230 of the lock plate 220 faces radially inwardly (e.g., see FIG. 13). For example, the collar 226 of the lock plate 220 defines an axial passage 228 therethrough. In such examples, the gear set 230 may extend radially into the axial passage 228 from the collar 226. In such examples, the engagement members 215 of the locking gear 214 may face radially outwardly to mesh with the gear set 230 (e.g., see FIG. 12). For example, the locking gear 214 may include a hub 246 configured to extend through the axial passage 228 (e.g., see FIG. 11). The engagement members 215 may extend radially outwardly from the hub 246 (e.g., FIG. 12). In certain examples, the gear set 230 and engagement members 215 may be splined together.

[0036] In certain implementations, a biasing member 134 (e.g., one or more wave springs) bias the collar member 126, 226 of the lock plate 120, 220 towards the non-locking position. For example, the biasing member 134 may push against a biasing surface 136, 236 of the lock plate collar 126, 226. In certain examples, the biasing member 134 is supported by the lockinggear 114, 214. In some examples, the biasing member 134 is disposed radially inwardly from the gear set 130, 230 and engagement members 115, 215. In other examples, the biasing member 134 is axially aligned with one or both of the gear set 130, 230 and engagement members 115, 215.

[0037] In certain implementations, the locking arrangement 118, 218 also includes an armature 144 that is axially movable relative to the differential housing 102. The armature 144 moves between a first position (e.g., see FIG. 5) and a second position (e.g., see FIG. 6). The axial movement of the armature 144 is controlled using an electromagnet 142 (e.g., a conductive coil) disposed at the stator 140. The armature 144 is formed of a ferrous material and / or includes a ferrous coating. When the electromagnet 142 is turned off (e.g., when current is not running through the electromagnet 142), the biasing member 134 biases the armature 144 to the first position. When the electromagnet 142 is energized, the electromagnet 142 moves the armature 144 to the second position.

[0038] In some implementations, the armature 144 and stator 140 are disposed at a flangeside of the differential housing 102 (e.g., see FIGS. 2 and 11). In other implementations, the armature 144 and stator 140 are disposed at a case-side of the differential housing 102. In certain implementations, the armature 144 is disposed at an opposite side of the stator 140 and electromagnet 142 from the flange 104 of the differential housing 102. In such implementations, energizing the electromagnet 142 magnetically pulls the armature 144 towards the differential housing 102. The biasing member 134 pushes the armature 144 away from the stator 140 and differential housing 102. In certain examples, the biasing member 134 acts on the armature 144 via the lock plate 120, 220.

[0039] In certain implementations, the legs 132, 232 of the lock plate 120, 220 extend through the differential housing 102 towards the armature 144. When the armature 144 moves from the first position to the second position, the armature 144 contacts and pushes against the legs 132, 232 of the lock plate 120, 220 to move the lock plate 120, 220 against the bias of the biasing member 134 to the locking position. When the armature 144 is released by the electromagnet 142, the biasing member 134 presses against the collar 126, 226 of the lock plate 120, 220 to move the lock plate 120, 220 to the non-locking position. The legs 132, 232 of the lock plate 120, 220 move with the collar 126, 226 to press against the armature 144 to move the armature 144 back to the first position.

[0040] By forming the legs 132, 232 integrally with the lock plate 120, 220, the response time of the locking arrangement 118, 218 is enhanced compared to having separate legs / rods.The lock plate 120, 220 need not travel before engaging the legs / rods to push the legs / rods towards the armature 144.

[0041] FIGS. 7-9 illustrate one example implementation of a lock plate 120 suitable for use in the locking arrangement 118. FIG. 13 illustrates another example implementation of a lock plate 220 suitable for use in the locking arrangement 218. The lock plate 120, 220 extends along an axial length between a first end 122, 222 and a second end 124, 224. The collar 126, 226 is disposed at the first end 122, 222. The free ends 132b, 232b of the legs 132, 232 define the second end 124, 224. In certain examples, when mounted within the differential housing 102, the length extends either coaxial or parallel to the rotational axis R of the differential housing 102.

[0042] The gear set 130, 230 of the lock plate 120, 220 is disposed in a ring around the annular biasing surface 136 of the collar 126, 226. The biasing surface 136 surrounds the passage 128, 228. In certain examples, the biasing surface 136 is recessed inwardly from the first end 122, 222. In certain implementations, the collar 126, 226 has a cylindrically-shaped outer periphery. In certain examples, the outer periphery of the collar 126, 226 is devoid of lugs or other protrusions as will be discussed more herein. In certain examples, the outer periphery of the collar 126, 226 is devoid of grooves or other detents. In certain implementations, the collar 126, 226 has a cylindrically-shaped inner periphery. In some examples, the inner periphery of the collar 126, 226 is devoid of protrusions or detents. In other examples, the inner periphery defines the gear set 230 as discussed above.

[0043] In certain implementations, each of the legs 132, 232 has a continuous external surface. In certain implementations, one or more of the legs 132, 232 tapers inwardly as the leg extends axially away from the collar 126, 226. In certain implementations, the leg 132, 232 tapers inwardly along a radial axis T as the leg 132, 232 extends away from the collar 126, 226 (e.g., see FIG. 5). Accordingly, such legs 132, 232 reduce in thickness as they extend away from the collar 126, 226. In certain implementations, one or more of the legs 132, 232 tapers circumferentially inwardly as the leg 132, 232 extends along the radial axis T. For example, an inner end 131 of each leg 132, 232 may have a shorter circumferential length than an outer end 133. In certain examples, a leg 132, 232 can have a trapezoidal shaped transverse crosssection. In other examples, the legs 132, 232 can have square, oval, rectangular, circular, or other shape of transverse cross-section. In certain implementations, the free ends 132b, 232b of the legs 132, 232 are flat.

[0044] FIG. 10 illustrates part of the interior of the differential housing 102. The differential housing 102 defines a pocket 150 disposed between the hub portions 108, 110. The pocket 150 is configured to receive the lock plate 120, 220. The pocket 150 includes an inner surface 152 facing towards the hub portion 110. An inner peripheral wall 154 of the pocket 150 extends axially outwardly from an outer periphery of the inner surface 152. One or more apertures 156 are defined through the inner surface 152. In certain examples, a lip 158 extends outwardly from the inner surface 152 at an inner periphery of the inner surface 152. In certain implementations, the inner peripheral wall 154 is devoid of grooves or protrusions. In certain implementations, the inner peripheral wall 154 defines a smooth, continuous surface. In certain implementations, the inner peripheral wall 154 is configured to radially face the outer periphery of the collar 126, 226.

[0045] In accordance with aspects of the disclosure, the lock plate 120, 220 is rotationally fixed relative to the differential housing 102 by the legs 132, 232 of the lock plate 120, 220. When the lock plate 120, 220 is disposed at the pocket 150, an outer periphery the collar 126, 226 opposes the inner peripheral wall 154 of the pocket 150 and the legs 132, 232 extend through the apertures 156 of the inner wall 152. In some implementations, the inner wall 152 inhibits axial movement of the lock plate 120, 220 in the direction of the armature 144. In other implementations, the lip 158 inhibits the axial movement of the lock plate 120, 220 towards the armature 144 (e.g., see FIG. 4). Engagement with the locking gear 114, 214 inhibits axial movement of the lock plate 120, 220 in the direction away from the armature 144.

[0046] In certain implementations, the lock plate 120, 220 is configured to axially slide along a hub 146, 246 of the locking gear 114, 214 between the locking and non-locking positions. The cooperation between the hub 146, 246 and the inner peripheral wall 154 guides the lock plate 120, 220 along the axial slide. In certain implementations, the hub 146, 246 and the inner peripheral wall 154 cooperate to inhibit tilting of the lock plate 120, 220 as the lock plates 120, 220 slides. In certain implementations, contact between the smooth, continuous outer surface of the collar 126, 226 and the smooth, continuous surface of the inner peripheral wall 154 inhibits tilting of the lock plate 120, 220 relative to the differential housing 102.

[0047] Because the outer periphery of the collar 126, 226 and the inner peripheral wall 154 are smooth, the collar 126, 226 does not rotationally engage the peripheral wall 154. Rather, the torque of the differential housing 102 is transferred to the lock plate 120, 220 via engagement between the legs 132, 232 of the lock plate 120, 220 and the inner surfaces bounding the apertures 156. As shown in FIG. 4, the legs 132, 232 of the lock plate 120, 220extend through the apertures 156 towards the armature 144. In certain implementations, the apertures 156 narrow as the apertures 156 extend from the inner surface 152 to an exterior of the differential housing 102 (e.g., see FIG. 5).

[0048] Because the torque is transferred between the legs 132, 232 and the inner wall 152, the inner peripheral wall 154 of the pocket 150 may be devoid of grooves or other recesses. The lack of grooves or recesses enables the portion of the differential housing 102 surrounding the pocket 150 to be formed thicker, and hence stronger, compared to a housing made to support torque transfer at the outer periphery of the lock plate. The enhanced strength adjacent the flange 104 reduces the effects of stress imparted on the differential housing by the ring gear. In addition, the lock plate 120, 220 can be formed smaller (e.g., radially smaller) compared to a lock plate including radially extending lugs to receive torque. Reducing the size of the lock plate 120, 220 may facilitate assembly of the differential housing 102. For example, the differential housing 102 may be capable of being formed of one piece with assembly windows 105 instead of needing a two or more piece housing. In certain examples, the assembly windows 105 in the differential housing 102 may be formed smaller as they need not accommodate as large a component.

[0049] In certain implementations, the free ends 132b of the legs 132 are flat. In certain examples, the free ends 132b of the legs 132 contact a flat surface of the armature 144. In certain examples, the armature 144 defines a flat, annular contact surface for the free ends 132b of the legs 132 of the lock plate 120. In certain implementations, the annular contact surface of the armature 144 is axially offset from the portion of the armature 144 aligned with the electromagnetic coil 142.

[0050] Having described the preferred aspects and implementations of the present disclosure, modifications and equivalents of the disclosed concepts may readily occur to one skilled in the art. However, it is intended that such modifications and equivalents be included within the scope of the claims which are appended hereto.

Claims

What is claimed is:

1. A differential case assembly comprising: a stator including an electro-magnet; a differential housing configured to rotate relative to the stator about an axis of rotation, the differential housing defining a plurality of openings extending parallel with the axis of rotation; a differential gear set disposed within the gear housing, the differential gear set including a locking gear; a locking arrangement mounted to the differential housing, the locking arrangement including: an armature disposed external of the differential housing so that the stator is disposed between the armature and the differential housing, the armature being axially movable relative to the stator between first and second positions, the armature being configured to move to the second position when the electro-magnet is energized; and a lock plate disposed within the differential housing, the lock plate being movable relative to the locking gear between a locking position and a non-locking position, the lock plate including a plurality of legs extending outwardly from a collar, the collar defining a gear set configured to mesh with the locking gear when the lock plate is disposed in the locking position, each leg extending from a base end at the collar, through a respective one of the openings defined by the differential housing, to a free end, the lock plate being moved to the locking position when the free ends of the legs are pushed by the armature as the armature moves to the second position; and a biasing member configured to bias the armature to the first position.

2. The differential case assembly of claim 1, wherein the biasing member is disposed between the lock plate and the locking gear.

3. The differential case assembly of claim 1, wherein the biasing member includes a spring.

4. The differential case assembly of claim 3, wherein the spring is a wave spring.

5. The differential case assembly of any of claims 1-4, wherein the biasing member is configured to bias the lock plate to the non-locking position.

6. The differential case assembly of any of claims 1-5, wherein the locking gear includes a hub that extends through an inner passage defined by the collar of the lock plate so that the lock plate slides along the hub between the locking and non-locking positions.

7. The differential case assembly of any of claims 1-6, wherein the differential housing defines a pocket bounded by a wall defining the plurality of openings, wherein the lock plate is disposed within the pocket.

8. The differential case assembly of claim 7, wherein the lock plate is devoid of radially outwardly extending lugs and an inner peripheral wall of the pocket is devoid of any recesses.

9. The differential case assembly of any of claims 1-8, wherein the gear set of the collar faces in an opposite direction from the legs.

10. The differential case assembly of claim 9, wherein the gear set includes dog teeth.

11. The differential case assembly of any of claims 1-8, wherein the gear set of the collar extends radially inwardly towards the locking gear.

12. The differential case assembly of claim 11, and preferably of claims 6 and 11, wherein the hub of the locking gear extends through an inner passage defined by the collar of the lock plate, the gear set of the collar being disposed at the inner passage and extending towards the hub.

13. The differential case assembly of any of claims 1-12, wherein a snap-ring mounts within a groove defined by the differential housing to retain the armature at the differential housing.

14. The differential case assembly of any of claims 1-13, wherein each leg of the lock plate tapers inwardly along a radial thickness of the leg as the leg extends from the base to the free end.

15. The differential case assembly of any of claims 1-14, wherein each leg of the lock plate tapers inwardly along a circumferential width of the leg as the leg extends from the base to the free end.

16. The differential case assembly of any of claims 1-15, wherein the legs have flat ends facing the armature.

17. The differential case assembly of claim 16, wherein the legs have smooth outer surfaces to the flat ends.

18. The differential case assembly of any of claims 1-17, wherein the lock plate is devoid of radially outwardly extending lugs.

19. The differential case assembly of any of claims 1-18, wherein each leg has a generally trapezoidal transverse cross-sectional shape.

20. The differential case assembly of any of claims 1-19, wherein the armature includes a flat, annular surface axially aligned with the free ends of the legs of the lock plate.

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