Electronic locking differential

Abstract

Play in the locking system of a differential assembly can be reduced to improve lock detection accuracy. A sensor tracks the position of an armature device that moves in response to energization / de-energization of an electromagnet to lock and unlock the differential assembly. Reducing the play allows the detection system to better determine the position of the armature based on the sensor reading. Exemplary structures for reducing the play include a biasing ring to hold the armature in a particular position, a shim disposed between the differential housing and the stator to hold the stator in a particular position relative to the differential housing, and a stop member to hold the armature in a particular position when the differential assembly is unlocked.

Description

Cross-reference to related applications

[0001] This application claims the benefit of Indian Provisional Application No. 202411027010, filed on 1 April 2024, the contents of which are incorporated herein by reference in their entirety. Background Technology

[0002] During normal operation of a motor vehicle, it is common for all four wheels not to rotate at the same rate. Different wheel rotation rates most frequently occur when the vehicle is cornering, but can also be caused by braking or uneven road surface conditions. To accommodate different wheel rotation rates while continuously directing power to both wheels, a differential is configured to allow different wheel rotation rates between the driven wheels. A differential allows wheels to rotate at different rates while transmitting torque to each wheel.

[0003] While this solution may be satisfactory under certain driving conditions, it is unsatisfactory when the coefficient of friction of the surface experienced by one of the driven wheels is much lower than that of the surfaces engaged by one or more other wheels. This condition may prevent torque from being applied to the wheel with more traction, resulting in undesirable vehicle performance. A locking mechanism can be configured to lock the differential and prevent different wheel rotation rates, and in at least some cases, distribute torque evenly between the two wheels. Summary of the Invention

[0004] A differential assembly includes an armature that is actuated, for example, when wheel slippage occurs. Actuating the armature engages a locking gear with a differential gear assembly. A lock-up detection sensor (e.g., a Hall effect position sensor) tracks the position of the armature to determine whether the differential assembly is locked at any given time. Reducing backlash in the system can tighten the association between a given armature position and the corresponding lock-up state, thereby providing improved accuracy in determining the lock-up state of the differential assembly.

[0005] In some implementations, a biasing ring is provided at the slip ring to hold the armature device in a specific position relative to the slip ring.

[0006] In some implementations, a gasket is provided between the differential housing and the stator to hold the stator in a specific position relative to the differential housing.

[0007] In some implementations, a stop member is provided on the outside of the differential housing. When the differential assembly is unlocked, the slip ring is pressed against the stop member.

[0008] Several other aspects of the invention will be set forth in the description below. These aspects may involve individual features and combinations thereof. It should be understood that the foregoing general description and the following detailed description are merely exemplary and illustrative, and do not limit the broad inventive concept on which the embodiments disclosed herein are based. Attached Figure Description

[0009] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate several aspects of this disclosure. A brief description of the drawings is as follows:

[0010] Figure 1 This is a cross-sectional view of an exemplary locking differential assembly for a vehicle, the locking differential assembly including a locking device having an armature plate biased to a predetermined position relative to a slip ring.

[0011] Figure 2 It shows Figure 1 The enlarged section.

[0012] Figure 3 This is a cross-sectional view of another exemplary locking differential assembly for a vehicle, which includes a locking device having a shim device selected to create a predetermined air gap between the armature plate and the stator of the locking device.

[0013] Figure 4 It shows Figure 3 The enlarged section.

[0014] Figure 5 This is a cross-sectional view of an exemplary locking differential assembly for a vehicle, the locking differential assembly including a locking device having an armature that is biased against a stop member when the locking device is unlocked.

[0015] Figure 6 It shows Figure 5 The enlarged section.

[0016] Figure 7 yes Figure 5 The cross-sectional view of the locking differential assembly taken along different cross-sectional planes makes the exemplary pin visible between the locking plate and the slip ring.

[0017] Figure 8 yes Figure 5 A perspective view of a portion of an exemplary locking differential assembly. Detailed Implementation

[0018] Reference will now be made in detail to exemplary aspects of this disclosure as illustrated in the accompanying drawings. Where possible, the same reference numerals will be used throughout the drawings to refer to the same or similar portions.

[0019] Figure 1-2 An exemplary locking differential 100 for a vehicle is shown. The locking differential 100 includes a differential housing 102 (e.g., a gear housing and end caps) configured to rotate about a longitudinal axis L of the differential housing 102. Torque input to the locking differential 100 can be provided to a flange 105 of the differential housing 102 by an input ring gear (not shown). The differential housing 102 defines annular hub portions 108 and 110 where the left and right axles can be coupled. A pair of bearing assemblies (not shown) disposed at the annular hub portions 108, 110 provide rotational support for the differential assembly 100, which rotates relative to an external differential housing or "carrier" (also not shown). The rotatable housing 102 defines a gear chamber in which a differential gear set 104 is disposed.

[0020] The stator 134 is disposed outside the differential housing 102. For example, the stator 134 may form a ring around the annular hub portion 108 of the differential housing 102. The differential housing 102 rotates relative to the stator 134. A retaining bracket 136 axially holds the stator 134 in the gear housing 102 (e.g., see...). Figure 8 In some examples, the retaining bracket 136 is mounted to the differential housing 102 using fasteners 137. Other mounting techniques are possible. In some examples, the inner shoulder 136a of the retaining bracket 136 abuts against the shoulder 134 of the stator 134 to axially retain the stator 134 to the differential housing 102 (see, for example, see...). Figure 3 and 4 In some examples, the retainer 136 extends only on a portion of the circumference of the stator 134 (e.g., see...). Figure 8 In some examples, multiple retaining brackets 136 are circumferentially spaced around the stator 134 to retain the stator 134 to the differential housing 102. In some embodiments, the stator 134 retains the electromagnet 135.

[0021] The locking differential 100 can operate in either a locked or unlocked mode. When operating in the locked mode, the side gear 106 of the differential gear set 104 is locked to prevent rotation relative to the differential housing 102. When operating in the unlocked mode, the side gear 106 is free to rotate relative to the differential housing 102. For example, the side gear 106 may be configured to rotate independently about the longitudinal axis L of the differential housing 102. In some embodiments, the locking differential 100 is manually switched between the locked and unlocked modes by a user. In other embodiments, the locking differential 100 automatically switches between the locked and unlocked modes (e.g., by the vehicle's microprocessor based on sensed vehicle operating conditions).

[0022] The locking differential 100 includes a locking device 118 that can switch between a locked configuration and an unlocked configuration. When in the locked configuration, the locking device 118 prevents independent rotation of the side gear 106 relative to the differential housing 102. When in the unlocked configuration, the locking device 118 allows independent rotation of the side gear 106 relative to the differential housing 102.

[0023] In some embodiments, the locking device 118 includes an armature device 120 and a locking plate 122, spaced apart by one or more pins 124 (e.g., see FIG. 9). The locking plate 122 is disposed within the differential housing 102. The armature device 120 is disposed outside the differential housing 102. In some examples, the armature device 120 may slide on the differential housing 102 during axial movement. For example, the armature device 120 may include a slip ring 128 surrounding the annular hub portion 108 and carrying the armature plate 119. In some examples, the pins 124 are engaged to the slip ring 128 using snap rings or other such fasteners. The pins 124 extend through the differential housing 102 to transmit axial movement between the armature device 120 and the locking plate 122.

[0024] The locking plate 122 engages with the differential housing 102 (e.g., via multiple lugs or other protrusions or pawls) such that the locking plate 122 rotates in unison with the differential housing 102. The locking plate 122 is configured to engage the locking gear assembly of the differential gear set 104 when the locking device 118 is in the locked configuration. When the locking device 118 is in the unlocked configuration, the locking plate 122 disengages from the locking gear assembly. In some embodiments, the locking gear assembly is integrated with the side gear 106, for example, as a dog tooth carried by the side gear 106.

[0025] The armature device 120 is axially movable relative to the stator 134 and relative to the differential housing 102 between a first position and a second position. When the armature device 120 is in the first position, the locking device 118 is in an unlocked configuration. When the armature device 120 is in the second position, the locking device 118 is in a locked configuration. In some examples, the armature device 120 is biased to the first position by a biasing member 126 (e.g., a wave spring). Therefore, the side gear 106 is allowed to rotate relative to the differential housing 102 until the locking device 118 is actuated. In some embodiments, when the electromagnet 135 is actuated (e.g., energized), the armature device 120 moves toward the second position against the bias of the biasing member 126.

[0026] For example, the armature plate 119 of the armature device 120 may be formed of a magnetizable (e.g., ferromagnetic) material. When the electromagnet 135 is energized, the electromagnet 135 attracts the armature plate 119, causing the slip ring 128 of the armature device 120 to move (e.g., slide) relative to the differential housing 102 along the axis L. As described above, the movement of the slip ring 128 is transmitted to the locking plate 122 via pins(a) 124 to selectively engage the locking gear mechanism.

[0027] In some embodiments, a biasing member 126 is disposed within the differential housing 102 to bias the locking plate 122 away from the locking gear assembly of the side gear 106. When the armature 120 moves to a second position against the biasing member 126, the armature 120 abuts against the pin 124 and moves against the locking plate 122 to press the locking plate 122 into engagement with the locking gear assembly. In some embodiments, the armature 120 is configured to rotate relative to the stator 134 together with the differential housing 102 and the pin 124. In other embodiments, the armature 120 is stationary relative to the stator 134, such that the pin 124 slides on the armature 120 (e.g., see FIG. 9).

[0028] According to aspects of this disclosure, the locked state of the differential assembly 100 can be determined from the axial position of the armature device 120. In some embodiments, a sensor device 150 monitors the axial position of the armature plate 119 relative to the stator 134. For example, a sensor target 152 (e.g., a magnet) may be mounted to the armature plate 119 to move with it, and a sensor 154 (e.g., a Hall effect sensor) may be fixedly mounted to the stator 134. The movement of the sensor target 152 relative to the sensor 154 changes the sensor reading, and a transfer function is used to determine the locked state based on the sensor reading.

[0029] In some embodiments, sensor readings are affected by clearance within the differential assembly 100. According to aspects of this disclosure, clearance within the differential assembly 100 can be tightened by including one or more strategic structures, which will be described in more detail below. Reducing clearance decreases the number of possible axial positions of the components of the locking device 118 during operation, thereby reducing sensor uncertainty between axial position and corresponding locking state.

[0030] In some embodiments, the armature plate 119 is held on the slip ring 128 by including a second biasing member 140 (e.g., a wave washer) (see, for example, see...). Figure 1 and 2This enhances the consistency of the axial position of the armature plate 119 of the armature assembly 120. The armature plate 119 is mounted radially around the slip ring 128. In the illustrated example, the first axial end 128a of the armature plate 119 abuts against the shoulder 129 of the slip ring 128. In this example, the armature plate 119 slides onto the slip ring 128 from the opposite side. A retaining member is then mounted to the slip ring 128 to hold the armature plate 119 on the slip ring 128. Using a second biasing member 140 as a retaining member to push the armature plate 119 against the shoulder 129 eliminates any gaps that might otherwise create play between the armature frame 119 and the slip ring 128.

[0031] In some embodiments, the consistency of the axial position of the stator 134 relative to the differential housing 102 is enhanced by including a shim device 142 between the stator 134 and the differential housing 102. In some embodiments, the shim device 142 is selected by a technician assembling the differential assembly 100 from a plurality of different shim device sizes to position the stator 134 at a predetermined distance from the armature plate 119. For example, the technician may select the shim device 142 from a plurality of shim devices with different thicknesses. In some examples, the thickness of the shim device 142 is selected to create a predetermined air gap length G between the stator 134 and the armature plate 119.

[0032] In some embodiments, a plurality of gasket devices 142 are circumferentially spaced along the stator 134. In some examples, the gasket devices 142 are positioned between the stator 134 and the differential housing 102 and are circumferentially aligned with the retaining brackets(s) 136. In some examples, the gasket devices 142 have the same shape and area as the retaining brackets 136. In this example, fasteners 137 that hold the retaining brackets 136 to the differential housing 102 also hold the gasket devices 142 to the differential housing 102.

[0033] In some embodiments, the biasing member 140 is used in combination with the shim device 142 to precisely position the armature plate 119 relative to the differential housing 102 and the stator 134.

[0034] In some embodiments, the consistency of the axial position of the armature assembly 120 relative to the locking plate 122 is enhanced by including a stop member 144 between the slip ring 128 and the differential housing 102. In some embodiments, the stop member 144 is positioned at a fixed axial position relative to the differential housing 102. In some examples, the stop member 144 includes a retaining ring mounted to one of the annular hub portions 108.

[0035] The biasing member 126 biases the locking plate 122 away from the locking mechanism of the side gear 106 and toward the inner surface of the differential housing 102 (e.g., toward the inner surface of the end cap). The locking plate 122 pushes the pins(s) 124 away from the differential gear 104. The pins 124 push the slip ring 128 of the armature assembly 120 away from the stator 134 and abut against the stop member 144. The axial position of the stop member 144 is selected such that when the armature assembly 120 and the locking plate 122 are in the unlocked position, the slip ring 128 is biased against the stop member 144 by the biasing member 126.

[0036] In some implementations, pins 124 are connected to slip ring 128 using snap rings 125 or other fasteners (see, for example, see...). Figure 7 For example, one end of each pin 124 can be inserted through an opening or slot in the slip ring 128, and a retaining ring 125 or other fastener can be mounted on that end to hold the pin 124 in place. Without the stop member 144, there may be play between the retaining ring 125 and the slip ring 128. For example, an air gap may exist between the retaining ring 125 and the slip ring 128. However, including the stop member 144 creates a positively connected locking system. When the locking system 118 is in the unlocked configuration, the biasing member 140 pushes the locking plate 122 against the pin 124, and the pin 124 pushes against the slip ring 128 to press the slip ring 128 against the stop member 144.

[0037] Exemplary embodiments of the present invention are described in the following aspects.

[0038] Aspect 1. A differential assembly, comprising:

[0039] Differential housing;

[0040] A differential gear set disposed within a differential housing, the differential gear set including a locking gear biased to an unlocked position;

[0041] A locking plate located inside the differential housing;

[0042] A stator disposed outside the differential housing, the stator comprising an electromagnet;

[0043] An armature assembly disposed outside the differential housing, configured to move relative to the differential housing and relative to the stator between a first position and a second position, the armature assembly comprising an armature carried by a slip ring that positions the armature axially aligned with an electromagnet, the armature being mounted to the slip ring using a biasing ring to hold the armature in a specific position relative to the slip ring; and

[0044] A pin extends between the armature device and the locking plate, such that the armature device is biased to a first position by the locking plate, and that the movement of the armature device to a second position by energizing an electromagnet is transmitted through the pin to push the locking plate into a locked position that engages with the locking gear of the differential gear set.

[0045] Aspect 2. The differential assembly according to aspect 1 further includes a position sensor disposed outside the differential housing; wherein the armature device carries a sensor target.

[0046] Aspect 3. The differential assembly according to aspect 2, wherein the sensor target includes a magnet and the position sensor includes a Hall effect sensor.

[0047] Aspect 4. The differential assembly according to Aspect 1, wherein the pin is one of a plurality of pins between the armature device and the locking plate; wherein the movement of the armature device to a second position by energizing an electromagnet is transmitted through the pin to push the locking plate into a locked position engaging with the locking gear of the differential gear set.

[0048] Aspect 5. The differential assembly according to aspect 1, wherein the bias ring includes a wave washer.

[0049] Aspect 6. The differential assembly according to aspect 1, wherein a first axial end of the armature abuts against a shoulder of a slip ring; and wherein a biasing ring pushes the armature against the shoulder.

[0050] Aspect 7. The differential assembly according to aspect 1, wherein the stator is held to the differential housing by a retaining clip.

[0051] Aspect 8. The differential assembly according to aspect 7, wherein a gasket is disposed between the differential housing and the stator to press the stator against the retaining clip.

[0052] Aspect 9. The differential assembly according to aspect 8, wherein the shims are selected from a plurality of shims of different thicknesses to position the stator at a predetermined distance from the armature.

[0053] Aspect 10. The differential assembly according to aspect 8, wherein the shim is one of a plurality of shims spaced apart along the stator circumferentially.

[0054] Aspect 11. The differential assembly according to aspect 8 further includes a retaining bracket for axially holding the stator at the differential housing, wherein an inner shoulder of the retaining bracket abuts against a shoulder of the stator to axially hold the stator to the differential housing.

[0055] Aspect 12. The differential assembly according to aspect 11, wherein the retaining bracket extends only on a portion of the stator circumference.

[0056] Aspect 13. The differential assembly according to aspect 11, wherein the gasket is positioned between the stator and the differential housing and is circumferentially aligned with the retaining bracket.

[0057] Aspect 14. The differential assembly according to aspect 11, wherein fasteners hold both the bracket and the gasket to the differential housing.

[0058] Aspect 15. The differential assembly according to any one of Aspects 1-14 further includes a stop member disposed between the slip ring and the differential housing, wherein when the armature device is in the first position, the pin pushes the slip ring away from the stator and abuts against the stop member.

[0059] Aspect 16. A differential assembly comprising:

[0060] Differential housing;

[0061] A differential gear set disposed within a differential housing, the differential gear set including a locking gear biased to an unlocked position;

[0062] A locking plate located inside the differential housing;

[0063] A stator, which is disposed outside the differential housing and held to the differential housing by a retaining clip, includes an electromagnet;

[0064] A gasket is placed between the differential housing and the stator to press the stator against the retaining clip;

[0065] An armature device disposed outside the differential housing, the armature device being configured to move relative to the differential housing and relative to the stator between a first position and a second position; and

[0066] A pin extends between the armature device and the locking plate, such that the armature device is biased to a first position by the locking plate, and that the movement of the armature device to a second position by energizing an electromagnet is transmitted through the pin to push the locking plate into a locked position that engages with the locking gear of the differential gear set.

[0067] Aspect 17. The differential assembly according to aspect 16, wherein the shim is one of a plurality of shims spaced apart along the stator circumferentially.

[0068] Aspect 18. The differential assembly according to aspect 16 further includes a retaining bracket for axially holding the stator at the differential housing, wherein an inner shoulder of the retaining bracket abuts against a shoulder of the stator to axially hold the stator to the differential housing, wherein a shim is positioned between the stator and the differential housing and is circumferentially aligned with the retaining bracket.

[0069] Aspect 19. A differential assembly comprising:

[0070] Differential housing;

[0071] A differential gear set disposed within a differential housing, the differential gear set including a locking gear biased to an unlocked position;

[0072] A locking plate located inside the differential housing;

[0073] A stator disposed outside the differential housing, the stator comprising an electromagnet;

[0074] An armature device disposed outside the differential housing, the armature device being configured to move relative to the differential housing and relative to the stator between a first position and a second position;

[0075] A pin, extending between the armature device and the locking plate, biases the armature device to a first position by the locking plate and transmits the motion of moving the armature device to a second position by energizing an electromagnet through the pin, thereby pushing the locking plate into a locked position engaged with the differential gear set; and

[0076] A stop member disposed outside the differential housing is positioned such that when the locking plate is in the unlocked position, the locking plate biases the armature device against the stop member via a pin, wherein when the locking plate is in the unlocked position, the locking plate is offset / misaligned from the inner shoulder of the differential housing.

[0077] Aspect 20. A differential assembly according to aspect 19, wherein the armature device includes an armature mounted to a slip ring; and wherein when the armature device is in a first position, a pin pushes the slip ring away from the stator and abuts against a stop member.

[0078] Preferred aspects and embodiments of this disclosure have been described, and modifications and equivalents of the disclosed concept will readily occur to those skilled in the art. However, it should be noted that such modifications and equivalents are included within the scope of the appended claims.

Claims

1. A differential assembly, comprising: Differential housing; A differential gear set disposed within a differential housing, the differential gear set including a locking gear biased to an unlocked position; A locking plate located inside the differential housing; A stator disposed outside the differential housing, the stator comprising an electromagnet; An armature assembly disposed outside the differential housing, the armature assembly being configured to move between a first position and a second position relative to the differential housing and relative to the stator, the armature assembly comprising an armature carried by a slip ring that positions the armature axially aligned with an electromagnet, the armature being mounted to the slip ring using a bias ring to hold the armature in a specific position relative to the slip ring; as well as A pin extends between the armature device and the locking plate, such that the armature device is biased to a first position by the locking plate, and that the movement of the armature device to a second position by energizing an electromagnet is transmitted through the pin to push the locking plate into a locked position that engages with the locking gear of the differential gear set.

2. The differential assembly according to claim 1 further includes a position sensor disposed outside the differential housing; wherein the armature device carries a sensor target.

3. The differential assembly according to claim 2, wherein, The sensor target includes a magnet, and the position sensor includes a Hall effect sensor.

4. The differential assembly according to claim 1, wherein, The pin is one of several pins between the armature device and the locking plate; the movement of the armature device to a second position by energizing the electromagnet is transmitted through the pin to push the locking plate into a locked position that engages with the locking gear of the differential gear set.

5. The differential assembly according to claim 1, wherein, The bias ring includes a wave washer.

6. The differential assembly according to claim 1, wherein, The first axial end of the armature abuts against the shoulder of the slip ring; the biasing ring pushes the armature against the shoulder.

7. The differential assembly according to claim 1, wherein, The stator is held to the differential housing by a retaining clip.

8. The differential assembly according to claim 7, wherein, A gasket is placed between the differential housing and the stator to press the stator against the retaining clip.

9. The differential assembly according to claim 8, wherein, The shims are selected from a number of shims with different thicknesses to position the stator at a predetermined distance from the armature.

10. The differential assembly of claim 8, wherein, A gasket is one of a plurality of gaskets spaced apart along the circumference of the stator.

11. The differential assembly of claim 8, further comprising a retaining bracket for axially retaining the stator at the differential housing, wherein an inner shoulder of the retaining bracket abuts against a shoulder of the stator to axially retain the stator to the differential housing.

12. The differential assembly of claim 11, wherein, The support extends only on a portion of the stator circumference.

13. The differential assembly of claim 11, wherein, The gasket is positioned between the stator and the differential housing, circumferentially aligned with the retaining bracket.

14. The differential assembly of claim 11, wherein, Fasteners will hold both the bracket and the gasket to the differential housing.

15. The differential assembly according to any one of claims 1-14, further comprising a stop member disposed between the slip ring and the differential housing, wherein when the armature device is in the first position, the pin pushes the slip ring away from the stator and abuts against the stop member.

16. A differential assembly, comprising: Differential housing; A differential gear set disposed within a differential housing, the differential gear set including a locking gear biased to an unlocked position; A locking plate located inside the differential housing; A stator, which is disposed outside the differential housing and held to the differential housing by a retaining clip, includes an electromagnet; A gasket is placed between the differential housing and the stator to press the stator against the retaining clip; An armature device disposed outside the differential housing, the armature device being configured to move relative to the differential housing and relative to the stator between a first position and a second position; as well as A pin extends between the armature device and the locking plate, such that the armature device is biased to a first position by the locking plate, and that the movement of the armature device to a second position by energizing an electromagnet is transmitted through the pin to push the locking plate into a locked position that engages with the locking gear of the differential gear set.

17. The differential assembly of claim 16, wherein, A gasket is one of a plurality of gaskets spaced apart along the circumference of the stator.

18. The differential assembly of claim 16, further comprising a retaining bracket for axially holding the stator at the differential housing, wherein an inner shoulder of the retaining bracket abuts against a shoulder of the stator to axially hold the stator to the differential housing, wherein a gasket is positioned between the stator and the differential housing and circumferentially aligned with the retaining bracket.

19. A differential assembly, comprising: Differential housing; A differential gear set disposed within a differential housing, the differential gear set including a locking gear biased to an unlocked position; A locking plate located inside the differential housing; A stator disposed outside the differential housing, the stator comprising an electromagnet; An armature device disposed outside the differential housing, the armature device being configured to move relative to the differential housing and relative to the stator between a first position and a second position; A pin extends between the armature device and the locking plate, such that the armature device is biased to a first position by the locking plate, and that the movement of the armature device to a second position by energizing an electromagnet is transmitted through the pin to push the locking plate into a locked position engaged with the differential gear set. as well as A stop member disposed outside the differential housing is positioned such that when the locking plate is in the unlocked position, the locking plate biases the armature device against the stop member via a pin, wherein when the locking plate is in the unlocked position, the locking plate is offset from the inner shoulder of the differential housing.

20. The differential assembly of claim 19, wherein, The armature device includes an armature mounted to the slip ring; when the armature device is in the first position, the pin pushes the slip ring away from the stator and abuts against the stop member.

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