Electronic locking differential

Abstract

A locking arrangement for a differential assembly includes an armature moved between first and second positions by a biasing member and an electromagnet. A stop arrangement maintains a spacing between the armature and the electromagnet (or a stator holding the electromagnet). The spacing allows the armature to rotate relative to the stator or electromagnet without drag from the stator or electromagnet. The stop arrangement can be monolithic with a gear housing or mounted to the gear housing as a separate piece.

Description

ELECTRONIC LOCKING DIFFERENTIALCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of Indian Provisional Application No. 202311085337, filed December 14, 2023, the disclosure of which is incorporated by reference in its entirety.BACKGROUND

[0002] During normal operation of a motor vehicle, it is common that all four wheels are not turning at an identical rate of speed. Different wheel turn rates are most commonly encountered when the vehicle is making a turn, but may also be caused by braking or non- uniform road surface conditions. In order to accommodate differing wheel turning rates while continuing to direct power to two wheels, a differential is configured to allow for different wheel turn rates between the powered wheels. The differential allows the wheels to spin at different rates while transmitting torque to each wheel.

[0003] While this solution may be satisfactory in some driving conditions, it is unsatisfactory under conditions where one of the driven wheels experiences a surface having a much lower coefficient of friction than a surface engaged by the other wheel(s). Such conditions may prevent the application of torque to a wheel with more traction, thereby resulting in undesired vehicle performance. A locking mechanism may be provided to lock the differential and prevent different wheel spin rates and transmit torque uniformly between two wheels in at least some circumstances.SUMMARY

[0004] In accordance with certain aspects of the disclosure, a differential assembly includes a locking arrangement that selectively fixes rotation of part of the differential gear set to a gear housing. The locking arrangement includes an armature that is axially movable by a biasing member and an electromagnet. A stop arrangement limits travel of the armature so that an air gap is maintained between the armature and the electromagnet and / or stator holding the electromagnet.

[0005] In some examples, the stop arrangement includes one or more separate parts that mount to the gear housing. In other examples, the stop arrangement is monolithically formed with the gear housing. In some examples, the stop arrangement includes a single physical stop(e.g., a ring-shaped stop). In other examples, the stop arrangement includes multiple physical stops (e.g., blocks) spaced from each other.

[0006] 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

[0007] 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:

[0008] FIG. 1 is a perspective view of an example differential arrangement having a locking arrangement configured in accordance with the principles of the present disclosure.

[0009] FIG. 2 is a perspective view of the differential arrangement of FIG. 1 with a stator and an armature of the locking arrangement exploded outwardly from a gear housing, the differential arrangement including a first type of stop arrangement to limit travel of an armature of the locking arrangement.

[0010] FIG. 3 is an enlarged view of a portion of FIG. 2 with the first type of stop arrangement exploded away from the gear housing.

[0011] FIG. 4 is an axial cross-section of the differential arrangement of FIG. 1 showing the first type of stop arrangement of FIG. 2.

[0012] FIG. 5 is an enlarged view of a portion of FIG. 4.

[0013] FIG. 6 is a perspective view of the differential arrangement of FIG. 1 with a stator and an armature of the locking arrangement exploded outwardly from a gear housing, the differential arrangement including a second type of stop arrangement to limit travel of an armature of the locking arrangement.

[0014] FIG. 7 is an enlarged view of a portion of FIG. 6.

[0015] FIG. 8 is an axial cross-section of the differential arrangement of FIG. 1 showing the second type of stop arrangement of FIG. 6.

[0016] FIG. 9 is an enlarged view of a portion of FIG. 8.

[0017] FIG. 10 is a perspective view of the differential arrangement of FIG. 1 with a stator and an armature of the locking arrangement exploded outwardly from a gear housing, thedifferential arrangement including a third type of stop arrangement to limit travel of an armature of the locking arrangement.

[0018] FIG. 11 is an enlarged view of a portion of FIG. 10.

[0019] FIG. 12 is an axial cross-section of the differential arrangement of FIG. 1 showing the third type of stop arrangement of FIG. 10.

[0020] FIG. 13 is an enlarged view of a portion of FIG. 12.DETAILED DESCRIPTION

[0021] 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.

[0022] FIGS. 1-5 show a locking differential 100 for a vehicle. The locking differential 100 includes a gear housing 102 (e.g., a gear case and an end cap) configured to rotate about a longitudinal axis L of the gear housing 102. Torque input to the locking differential 100 can be provided by an input ring gear (not shown) to a flange 105 of the gear housing 102. The gear housing 102 defines annular hub portions 108 and 110 (FIG. 5) at which left and right axle shafts can be coupled. A pair of bearing sets (not shown) disposed at the annular hub portions 108, 110 provide rotational support for the rotating differential device 100 relative to an outer differential housing or "carrier" (also not shown). The rotatable housing 102 defines a gear chamber 112 in which a differential gear set 114 is disposed.

[0023] A stator 134 is disposed external to the gear housing 102. For example, the stator 134 may form a ring surrounding the annular hub portion 110 of the gear housing 102. The gear housing 102 rotates relative to the stator 134. A snap-ring 136 axially retains the stator 134 at the gear housing 102 (e.g., at the annular hub portion 110). In certain implementations, the stator 134 holds an electromagnet (e.g., see FIG. 4).

[0024] The locking differential 100 can be operated in a locked mode or an unlocked mode. When operated in the locked mode, one or both side gears 126, 128 of the differential gear set 114 are locked against rotation relative to the gear housing 102. When operated in the unlocked mode, the side gears 126, 128 are free to spin relative to the gear housing 102. For example, the side gears 126, 128 may be configured to independently rotate about the longitudinal axis L of the gear housing 102. In some implementations, the locking differential 100 is transitioned between locked and unlocked modes manually by a user. In other implementations, the locking differential 100 is transitioned between locked andunlocked modes automatically (e.g., by a microprocessor of the vehicle based on a sensed operational condition of the vehicle).

[0025] The locking differential 100 includes a locking arrangement 118 that can be transitioned between a locking configuration and a non-locking configuration. When disposed in the locking configuration, the locking arrangement 118 inhibits independent rotation of the side gear 128 relative to the gear housing 102. When disposed in the nonlocking configuration, the locking arrangement 118 allows independent rotation of the side gear 128 relative to the gear housing 102.

[0026] In certain implementations, the locking arrangement 118 includes an armature 119 and a locking collar 122 spaced apart by one or more pins 124. The locking collar 122 is disposed within the gear housing 102. The armature 119 is disposed external of the gear housing 102. For example, the armature 119 may be annular member surrounding the annular hub portion 110. In such examples, the armature 119 may ride over the gear housing 102 during axial movement. The pins 124 extend through the gear housing 102 to transfer axial motion between the armature 119 and the locking collar 122.

[0027] The locking collar 122 is engaged with the gear housing 102 (e.g., through a plurality of ears or other protrusions or detents) so that the locking collar 122 spins in unison with the gear housing 102. The locking collar 122 is configured to engage a locking gear arrangement 130 when the locking arrangement 118 is disposed in the locking configuration. The locking collar 122 is disengaged from the locking gear arrangement 130 when the locking arrangement 118 is disposed in the non-locking configuration. In certain implementations, the locking gear arrangement 130 is integral with the side gear 128, e.g., as dog teeth carried by the side gear 128.

[0028] The armature 119 is axially movable relative to the stator 134 and relative to the gear housing 102 between first and second positions. The locking arrangement 118 is disposed in the non-locking configuration when the armature 119 is disposed in the first position. The locking arrangement 118 is disposed in the locking configuration when the armature 119 is disposed in the second position. In certain examples, the armature 119 is biased to the first position by a biasing member 140 (e.g., wave spring). Accordingly, the side gear 128 allowed to spin relative to the gear housing 102 until the locking arrangement 118 is actuated. In certain implementations, the armature 119 moves against the bias of the biasing member 140 towards the second position when the electromagnet 132 is actuated (e.g., energized). For example, the armature 119 may be formed of magnetizable (e.g., ferrous) material. When the electro-magnet 132 is energized, the electro-magnet 132 attractsthe armature 119, causing the armature 119 to move axially along the axis L relative to the gear housing 102.

[0029] In certain implementations, the biasing member 140 is disposed within the gear housing 102 to bias the locking collar 122 away from the locking gear arrangement 130. When the armature 119 moves to the second position against the bias of the biasing member 140, the armature 119 abuts against and moves the pins 124 against the locking collar 122 to press the locking collar 122 into engagement with the locking gear arrangement 130. In some implementations, the armature 119 is configured to rotate with the gear housing 102 and pins 124 relative to the stator 134. In other implementations, the armature 119 is rotationally stationary relative to the stator 134 so that the pins 124 glide over the armature 119.

[0030] In certain implementations, the armature 119 includes an inner disc 119a and an outer ring 119b. The inner disc 119a is supported on a portion of the gear housing 102. In certain examples, the pins 124 aligns with the inner disc 119a. The outer ring 119b aligns with the electromagnet 132. The inner disc 119a rides over the gear housing 102 towards the differential gear set 114 when the outer ring 119b is attracted to the electromagnet 132. The inner disc 119a pushes against the pins 124 when the armature 119 is moved to the second position. The pins 124 push against the inner disc 119a to bias the armature 119 back to the first position.

[0031] In certain implementations, the gear housing 102 radially tapers or steps down at the hub portion 110. In certain examples, the gear housing 102 tapers or steps radially inward to a first annular seat 162 on which the stator 134 is mounted (e.g., see FIG. 5). In certain examples, the stator 134 is held to the first annular seat 162 by a snap-ring 164. In certain implementations, the gear housing 102 tapers or steps radially inward from the first annular seat 162 to a second annular seat 166. A step surface 165 extends between the first and second annular seats 162, 166. In certain examples, the armature 119 is held to the second annular seat 166 by the snap-ring 136. The armature 119 (e.g., the inner disc 119a) rides along the second annular seat 166 when the armature 119 is moved between the first and second positions.

[0032] In accordance with certain aspects of the disclosure, the locking arrangement 118 and gear housing 102 are configured to inhibit contact between the armature 119 and the stator 134. For example, the gear housing 102 may be configured to limit travel of the armature 119 via a stop arrangement 150 of one or more physical stops. The limited travel stops the armature 119 from sliding a sufficient distance to contact the stator 134.Maintaining a gap (e.g., an air gap) between the armature 119 and the stator 134 regardless ofthe position of the armature 119 reduces frictional drag on the torque being applied to the gear housing 102.

[0033] In some implementations, the stop arrangement 150 is formed separately from the gear housing 102 and mounted to the gear housing 102 (e.g., see FIGS. 1-9). In other implementations, the stop arrangement 150 is monolithically formed with the gear housing 102 (e.g., see FIGS. 10-13). In some implementations, the stop arrangement 150 encircles the hub portion 110 (e.g., see FIGS. 1-5). In other implementations, the stop arrangement 150 includes discrete sections disposed about a circumference of the hub portion 110 (e.g., see FIGS. 6-13). In various examples, the stop arrangement 150 can be formed of a rigid material such as plastic (e.g., nylon), stainless steel, or ductile cast iron. The stop arrangement 150 is sufficiently rigid to inhibit contact between the outer portion 119b of the armature 119 and the stator 134 and / or the electromagnet 132.

[0034] In certain examples, the stop arrangement 150 is disposed to inhibit movement of the inner disc 119a of the armature 119 along the longitudinal axis L relative to the second annular seat 166. Accordingly, in certain examples, the travel of the armature 119 is bounded on one side by the stop arrangement 150 and on the other side by the snap-ring 136. In certain examples, the stop arrangement 150 is disposed to abut the radial step between the first and second annular seats 162, 166 (e.g., see FIGS. 4 and 5). In certain examples, the stop arrangement 150 is mounted to the step surface 165 between the first and second annular seats 162, 166.

[0035] FIGS. 1-5 illustrate a first example implementation of a stop arrangement 150. The first stop arrangement 150 includes a ring 152 of material encircling the second annular seat 166 (e.g., see FIG. 2). In certain examples, the ring 152 is disposed axially between the step surface 165 and the disc portion 119a of the armature 119. In some examples, the ring 152 is attached (e.g., adhesively affixed, welded, fastened, etc.) to the step surface 165. In other examples, the ring 152 is free-floating over the second annular seat 166. In various examples, the ring 152 can be formed of the rigid material, such as plastic (e.g., nylon), stainless steel, or ductile cast iron. In certain examples, the ring 152 defines notches 153 (FIG. 3) to accommodate the pins 124 (e.g., see FIG. 2). In certain examples, the ring 152 can be retrofit to an existing gear housing 102 to limit travel of the armature 119.

[0036] FIGS. 6-9 illustrate a second example implementation of a stop arrangement 150. The second stop arrangement 150 includes one or more blocks 154 spaced from each other about a circumference of the second annular seat 166 to extend axially beyond the radial step 165. Each block 154 is secured to the step surface 165. In the example shown, each block154 is fastened to the step surface 165 using a respective fastener (e.g., a screw or bolt) 155. In other examples, each block 154 can be glued, welded, or otherwise attached to the step surface 165. In still other examples, each block 154 can be glued, welded, or otherwise secured to the second annular seat 166.

[0037] In the example shown, the stop arrangement 150 includes three blocks 154. In other examples, however, the stop arrangement 150 can include a greater or lesser number (e.g., one, two, four, five, ten, etc.) of blocks 154. In some examples, a total surface area of the blocks 154 is less than half of a total surface area of the step surface 165. In certain examples, a total surface area of the blocks 154 is less than a third of a total surface area of the step surface 165. In certain examples, a total surface area of the blocks 154 is less than a quarter of a total surface area of the step surface 165. In certain examples, a total surface area of the blocks 154 is less than a tenth of a total surface area of the step surface 165.

[0038] In certain examples, the blocks 154 have a common shape. In certain examples, the blocks 154 have a common size. In the example shown, the blocks 154 have a trapezoidal shape. In other examples, however, the blocks 154 can have any shape (e.g., rectangular, circular, oval, triangular, an annulus sector, etc.).

[0039] FIGS. 10-13 illustrate a third example implementation 156 of a stop arrangement 150. The third stop arrangement 150 includes one or more raised blocks 156 of the step surface 165. The raised blocks 156 are monolithically formed with the gear housing 102. As discussed above with respect to blocks 154, the raised blocks 156 can have any desired shape. In the example shown, multiple blocks 156 extend axially past the step surface 165 to form the stop arrangement 150. In another example, a continuous ring may extend axially outwardly from the step surface 165 to define the stop surface 150. In such an example, the continuous ring would resemble the ring 152 of FIGS. 1-6, but would be integral with the gear housing 102.

[0040] In the example shown, the stop arrangement 150 includes three raised blocks 156. In other examples, however, the stop arrangement 150 can include a greater or lesser number (e.g., one, two, four, five, ten, etc.) of blocks 156. In some examples, a total surface area of the blocks 156 is less than half of a total surface area of the step surface 165. In certain examples, a total surface area of the blocks 156 is less than a third of a total surface area of the step surface 165. In certain examples, a total surface area of the blocks 156 is less than a quarter of a total surface area of the step surface 165. In certain examples, a total surface area of the blocks 156 is less than a tenth of a total surface area of the step surface 165.

[0041] Examples of the disclosure may be described according to the following aspects.

[0042] Aspect 1. A differential assembly comprising:

[0043] a stator including an electro-magnet;

[0044] a gear housing configured to rotate relative to the stator about a longitudinal axis of the gear housing;

[0045] a differential gear set disposed within the gear housing, the differential gear set including a locking gear;

[0046] a locking arrangement mounted to the gear housing, the locking arrangement including:

[0047] a locking collar disposed within the gear housing, the locking collar being movable relative to the locking gear between a locking position and a non-locking position;

[0048] an armature disposed external of the gear housing, the armature being axially movable relative to the stator between first and second positions, the armature being biased to the first position and the armature being configured to move to the second position when the electro-magnet is energized;

[0049] a pin extending between the locking collar and the armature, the pin being configured to transfer axial motion between the locking collar and the armature, wherein the locking collar is disposed in the non-locking position when the armature is disposed in the first position and the locking collar is disposed in the locking position when the armature is disposed in the second position; and

[0050] a stop arrangement disposed at the gear housing to limit travel of the armature towards the stator.

[0051] Aspect 2. The differential assembly of aspect 1, wherein the stop arrangement includes a physical stop member against which the armature abuts when moved to the second position.

[0052] Aspect 3. The differential assembly of aspect 2, wherein the physical stop member has a ring shape.

[0053] Aspect 4. The differential assembly of aspect 2, wherein the physical stop member is one of a plurality of blocks disposed in alignment with the armature.

[0054] Aspect 5. The differential assembly of aspect 4, wherein the blocks are attached to the gear housing.

[0055] Aspect 6. The differential assembly of aspect 4, wherein the blocks are monolithically formed with the gear housing.

[0056] Aspect 7. The differential assembly of aspect 1, wherein the stop arrangement maintains an air gap between the armature and the stator.

[0057] Aspect 8. The differential assembly of aspect 1, wherein the stop arrangement is formed separately from the gear housing and mounted to the gear housing.

[0058] Aspect 9. The differential assembly of aspect 1, wherein the stop arrangement is monolithically formed with the gear housing.

[0059] Aspect 10. The differential assembly of aspect 1, wherein travel of the armature is bounded on one side by the stop arrangement and on the other side by a snap-ring.

[0060] Aspect 11. The differential assembly of aspect 1, wherein the gear housing radially steps down at a hub portion to a first annular seat on which the stator is mounted, wherein the gear housing steps radially inward from the first annular seat to a second annular seat; and wherein a step surface extends between the first and second annular seats.

[0061] Aspect 12. The differential assembly of aspect 11, wherein the stop arrangement is disposed to abut the step surface.

[0062] Aspect 13. The differential assembly of aspect 11, wherein the stop arrangement is mounted to the step surface.

[0063] Aspect 14. A locking arrangement for a differential gear housing, the locking arrangement comprising:

[0064] a locking collar disposed within the gear housing, the locking collar being movable relative to the locking gear between a locking position and a non-locking position;

[0065] an armature disposed external of the gear housing, the armature being axially movable relative to the stator between first and second positions, the armature being biased to the first position and the armature being configured to move to the second position when the electro-magnet is energized;

[0066] a pin extending between the locking collar and the armature, the pin being configured to transfer axial motion between the locking collar and the armature, wherein the locking collar is disposed in the non-locking position when the armature is disposed in the first position and the locking collar is disposed in the locking position when the armature is disposed in the second position; and

[0067] a stop arrangement disposed at the gear housing to limit travel of the armature towards the stator.

[0068] Aspect 15. The locking arrangement of aspect 14, wherein the stop arrangement includes a physical stop member against which the armature abuts when moved to the second position.

[0069] Aspect 16. The locking arrangement of aspect 15, wherein the physical stop member has a ring shape.

[0070] Aspect 17. The locking arrangement of aspect 15, wherein the physical stop member is one of a plurality of blocks disposed in alignment with the armature.

[0071] Aspect 18. The locking arrangement of aspect 17, wherein the blocks are attached to the gear housing.

[0072] Aspect 19. The locking arrangement of aspect 17, wherein the blocks are monolithically formed with the gear housing.

[0073] Aspect 20. A method of locking a differential assembly, the method comprising:

[0074] providing a differential gear set within a gear housing, the differential gear set including a locking collar;

[0075] mounting a stator about a hub of the gear housing, the stator including an electro-magnet;

[0076] mounting an armature about the hub of the gear housing so that the armature is located at an opposite side of the stator from a majority of the gear housing;

[0077] mounting a retainer to the hub to limit movement of the armature in a first direction away from the stator; and

[0078] mounting a stop arrangement between the stator and the armature to limit movement of the armature in a second direction towards the stator.

[0079] 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 assembly comprising: a stator including an electro-magnet; a gear housing configured to rotate relative to the stator about a longitudinal axis of the gear housing; a differential gear set disposed within the gear housing, the differential gear set including a locking gear; a locking arrangement mounted to the gear housing, the locking arrangement including: a locking collar disposed within the gear housing, the locking collar being movable relative to the locking gear between a locking position and a non-locking position; an armature disposed external of the gear housing, the armature being axially movable relative to the stator between first and second positions, the armature being biased to the first position and the armature being configured to move to the second position when the electro-magnet is energized; a pin extending between the locking collar and the armature, the pin being configured to transfer axial motion between the locking collar and the armature, wherein the locking collar is disposed in the non-locking position when the armature is disposed in the first position and the locking collar is disposed in the locking position when the armature is disposed in the second position; and a stop arrangement disposed at the gear housing to limit travel of the armature towards the stator.

2. The differential assembly of claim 1, wherein the stop arrangement includes a physical stop member against which the armature abuts when moved to the second position.

3. The differential assembly of claim 2, wherein the physical stop member has a ring shape.

4. The differential assembly of claim 2, wherein the physical stop member is one of a plurality of blocks disposed in alignment with the armature.

5. The differential assembly of claim 4, wherein the blocks are attached to the gear housing.

6. The differential assembly of claim 4, wherein the blocks are monolithically formed with the gear housing.

7. The differential assembly of claim 1, wherein the stop arrangement maintains an air gap between the armature and the stator.

8. The differential assembly of claim 1, wherein the stop arrangement is formed separately from the gear housing and mounted to the gear housing.

9. The differential assembly of claim 1, wherein the stop arrangement is monolithically formed with the gear housing.

10. The differential assembly of claim 1, wherein travel of the armature is bounded on one side by the stop arrangement and on the other side by a snap-ring.

11. The differential assembly of claim 1, wherein the gear housing radially steps down at a hub portion to a first annular seat on which the stator is mounted, wherein the gear housing steps radially inward from the first annular seat to a second annular seat; and wherein a step surface extends between the first and second annular seats.

12. The differential assembly of claim 11, wherein the stop arrangement is disposed to abut the step surface.

13. The differential assembly of claim 11, wherein the stop arrangement is mounted to the step surface.

14. A locking arrangement for a differential gear housing, the locking arrangement comprising: a locking collar disposed within the gear housing, the locking collar being movable relative to the locking gear between a locking position and a non-locking position;an armature disposed external of the gear housing, the armature being axially movable relative to the stator between first and second positions, the armature being biased to the first position and the armature being configured to move to the second position when the electromagnet is energized; a pin extending between the locking collar and the armature, the pin being configured to transfer axial motion between the locking collar and the armature, wherein the locking collar is disposed in the non-locking position when the armature is disposed in the first position and the locking collar is disposed in the locking position when the armature is disposed in the second position; and a stop arrangement disposed at the gear housing to limit travel of the armature towards the stator.

15. The locking arrangement of claim 14, wherein the stop arrangement includes a physical stop member against which the armature abuts when moved to the second position.

16. The locking arrangement of claim 15, wherein the physical stop member has a ring shape.

17. The locking arrangement of claim 15, wherein the physical stop member is one of a plurality of blocks disposed in alignment with the armature.

18. The locking arrangement of claim 17, wherein the blocks are attached to the gear housing.

19. The locking arrangement of claim 17, wherein the blocks are monolithically formed with the gear housing.

20. A method of locking a differential assembly, the method comprising: providing a differential gear set within a gear housing, the differential gear set including a locking collar; mounting a stator about a hub of the gear housing, the stator including an electromagnet; mounting an armature about the hub of the gear housing so that the armature is located at an opposite side of the stator from a majority of the gear housing;mounting a retainer to the hub to limit movement of the armature in a first direction away from the stator; and mounting a stop arrangement between the stator and the armature to limit movement of the armature in a second direction towards the stator.

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