Electronic locking differential
By introducing electromagnets and cam mechanisms into the locking differential, compact locking under high torque is achieved, solving the problem of large space occupancy in the prior art, and improving the compactness and efficiency of the system.
Patent Information
- Application Number
- CN202211142299.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Priority Date
- 2022-09-14
- Filing Date
- 2022-09-20
- Publication Date
- 2024-12-17
- Estimated Expiration
- 2042-09-20
AI Technical Summary
Existing locked differentials require a larger actuator to offset the vector component at high torque conditions, resulting in a larger space occupancy and a larger space required for integrated actuators and cam mechanisms.
The electronic lock differential design is adopted, including a bracket, a differential gear set, a first claw member, a second claw member, a cam mechanism, a spring and an electromagnet. The electromagnetic field is generated by the electromagnet to make the second claw member in the Move axially and use a cam mechanism and a spring to push the second claw member to the locked position when torque is transmitted.
Reduces the size requirement of the actuator, reduces space occupation, and effectively locks the differential gear set in high torque, improving the compactness and efficiency of the system.
Smart Images
Figure CN115839397B_ABST
Abstract
Description
[0001] CROSS-REFERENCE TO RELATED APPLICATIONS
[0002] This application claims the benefit of U.S. Provisional Application No. 63 / 245,994, filed on September 20, 2021, the disclosure of which is incorporated herein by reference as if fully set forth herein. Technical Field
[0003] The present disclosure relates to an electronic locking differential. Background Art
[0004] This section provides background information related to the present disclosure which is not necessarily prior art.
[0005] A locking differential is used in a vehicle driveline to suppress speed differences between a pair of driven wheels, typically in situations where one wheel is susceptible to slip and enhanced traction is desired. A locking differential typically employs a dog clutch that is selectively engaged to lock the side gears of the differential gear set to a carrier or differential case housing the differential gear set. Such a configuration may employ a first dog member having a plurality of dog clutch teeth and non-rotatably coupled to the side gears, and a second dog member having a plurality of matching dog clutch teeth and non-rotatably but axially slidably coupled to the carrier. The second dog member may be positioned along the rotational axis of the carrier in a first position and a second position, in which the matching dog clutch teeth are disengaged from the dog clutch teeth so that the dog clutch does not suppress relative rotation between the side gears and the carrier, and in which the matching dog clutch teeth are engaged with the dog clutch teeth so that the dog clutch suppresses relative rotation between the side gears and the carrier.
[0006] During operation of such a locking differential, the forces acting on the dog clutch teeth and the mating dog clutch teeth include vector components that tend to push the second claw member axially away from the first claw member (i.e., toward the first position of the second claw member). In situations where relatively large amounts of torque are transmitted through the dog clutch, these vector components can become relatively large. One strategy for counteracting these vector components involves using a relatively powerful actuator that is used to move the second claw member. More specifically, the actuator can be "oversized" so that it generates sufficient load to not only move the second claw member, but also generates sufficient force to overcome the vector components and maintain the second claw member in the second position.
[0007] U.S. Patent No. 7,074,150 discloses a locking differential with an electromagnetic actuator and a dog clutch. A cam mechanism is integrated into the second claw member and the bracket and is used to generate a counteracting force that reduces the vector component that tends to drive the second claw member away from the first claw member. Although this configuration reduces the "oversizing" requirement for the actuator used to move the second claw member, we note that integrating the actuator and cam mechanism into the locking differential requires a relatively large space. Summary of the invention
[0008] This section provides a general summary of the disclosure, but is not a comprehensive disclosure of its full scope or all of its features.
[0009] In one form, the present disclosure provides an electronic locking differential, including a carrier, a differential gear set, a first claw member, a second claw member, a cam mechanism, a spring, and an electromagnet. The carrier is rotatable about a differential axis and defines an inner cavity, an actuator hub, a plurality of leg holes, and a circumferentially extending protrusion. The actuator hub has an outer hub surface concentrically arranged about the differential axis. The leg holes are spaced apart about the differential axis, and each of the leg holes intersects the inner cavity. The circumferentially extending protrusion is coaxial with the outer hub surface and has a radial inner side defining a first frustoconical surface. An annular recess is radially formed between the outer hub surface and the first frustoconical surface. The differential gear set is housed in the inner cavity and includes a side gear rotatable about the differential axis relative to the carrier. The first claw member is fixedly coupled to the side gear and has a plurality of first teeth. The second claw member is housed in the inner cavity and has a body and a plurality of legs. The body defines a plurality of second teeth. Each of the legs is fixedly coupled to the body and is received by a related one of the leg holes. Each of the legs has a distal end opposite to the body and of a cylindrical shape, and a second claw-shaped member is axially movable along the differential axis between a first position in which the second tooth is disengaged from the first tooth and a second position in which the second tooth is engaged with the first tooth. The cam mechanism has a plurality of cams and a plurality of followers. Each of the cams is formed on a corresponding one of the legs at a position between the body and the distal end of the cylindrical shape. Each of the followers is fixedly coupled to the bracket and disposed in the inner cavity. Each of the cams can engage with a related one of the followers. A spring biases the second claw-shaped member toward the first position along the differential axis. An electromagnet is slidably disposed on the actuator hub. The electromagnet has a pole piece and a plunger fixedly coupled to the pole piece. The pole piece defines a second frustoconical surface. The plunger abuts the axial end surface of the distal end of the leg. The electromagnet is operable in an energized state to generate a magnetic field that pulls the second frustoconical surface on the pole piece toward the first frustoconical surface, thereby correspondingly moving the second claw member toward the second position. When the electromagnet is operated to generate the magnetic field and the second claw member is in the second position, at least a portion of the electromagnet is disposed in the annular recess. The cam mechanism is configured to push the second claw member toward the first claw member when a torque greater than or equal to a first predetermined threshold is transmitted through the cam mechanism in a first predetermined rotational direction.
[0010] Further areas of applicability will become apparent from the description provided herein.The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS
[0011] The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.
[0012] Figure 1is a perspective view of an exemplary electronic locking differential constructed in accordance with the teachings of the present disclosure;
[0013] Figure 2 for Figure 1 Side view of the electronic locking differential in the;
[0014] Figure 3 For along Figure 2 A cross-sectional view taken along line 3-3 in FIG.
[0015] Figure 4 For along Figure 2 A cross-sectional view taken along line 4-4 in FIG.
[0016] Figure 5 and Figure 6 yes Figure 1 An exploded perspective view of the electronic locking differential in the
[0017] Fig. 7 is a perspective view of a second claw member;
[0018] FIG8 is an enlarged portion of FIG7 , illustrating a portion of the second claw member in more detail;
[0019] Fig. 9 is a front view of the second claw-shaped member;
[0020] Fig.10 for Figure 1 A perspective view of a portion of a carrier of an electronic locking differential in FIG. 1 , the view illustrating a follower formed on the carrier;
[0021] Fig.11 for Figure 1 a cross-sectional view of a portion of an electronic locking differential in , the view depicting engagement of a cam on a leg of a second claw member with a follower on a carrier;
[0022] Fig.12 is a cross-sectional view of a second exemplary electronic locking differential constructed in accordance with the teachings of the present disclosure;
[0023] Fig.13 for Fig.12 a perspective view of a portion of a locking differential in , illustrating a cover of a carrier and a cam follower of a cam mechanism in greater detail; and
[0024] Fig.14 for Fig.12 0026] A perspective view of a portion of a locked differential in FIG. 1, illustrating the second claw member and the cam member of the cam mechanism in more detail.
[0025] Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings. DETAILED DESCRIPTION
[0026] refer to Figures 1 to 3 An exemplary electronic locking differential constructed in accordance with the teachings of the present disclosure is generally designated by reference numeral 10. The locking differential 10 may include a differential case or carrier 12, a differential gear set 14, a first jaw member 16, a second jaw member 18, a cam mechanism 20, a spring 22, and an electromagnet 24.
[0027] refer to Figures 3 to 6 , the carrier 12 is rotatable about the differential axis 30 and defines an inner cavity 32, an actuator hub 34, a plurality of leg holes 36, and a circumferentially extending protrusion 38. A portion of the carrier 12 defining the inner cavity 32 may define a circumferential guide surface 40. The actuator hub 34 has an outer hub surface 44 disposed concentrically about the differential axis 30. The leg holes 36 are spaced apart about the differential axis 30, and each of the leg holes 36 intersects the inner cavity 32. The circumferentially extending protrusion 38 is coaxial with the outer hub surface 44 and has a radially inner side defining a first frustoconical surface 46. An annular recess 48 is formed radially between the outer hub surface 44 and the first frustoconical surface 46.
[0028] The bracket 12 can be integrally formed, but in the particular example shown, the bracket 12 is an assembly that includes a bracket body 52 and a cover 54 fixedly coupled to the bracket body 52, such as with threaded fasteners (not shown) or via welding. The circumferentially extending protrusion 38 can be fixedly coupled to the cover 54 (e.g., integrally formed therewith). In addition, the cover 54 can optionally define a circumferential guide surface 40.
[0029] The differential gear set 14 is housed in the internal cavity 32 and includes side gears 60 rotatable about the differential axis 30 relative to the carrier 12. The differential gear set 14 can be configured in any desired manner and can be a helical gear set including a plurality of differential pinions 62 in meshing engagement with the side gears 60. In the particular example shown, each of the differential pinions 62 is rotatably mounted on a cross pin 64, and the cross pin 64 is coupled to the carrier 12 for rotation therewith.
[0030] The first claw member 16 and the second claw member 18 form a claw clutch that is selectively operable to lock the electronic locking differential 10. The first claw member 16 is fixedly coupled to the side gear 60 (e.g., integrally formed therewith) and has a plurality of first teeth 70. The second claw member 18 is received in the inner cavity 32 and has a body 74 and a plurality of legs 76. The body 74 is received on a hub 80 formed on the side gear 60 and defines a plurality of second teeth 84 that can engage with the first teeth 70 on the first claw member 16. Each of the legs 76 is fixedly coupled to the body 74 and is received through an associated one of the leg holes 36.
[0031] refer to Figure 37 to 9, each of the legs 76 has a distal end 90 and a proximal end 92. The distal end 90 is opposite the body 74 and is cylindrical. In the example provided, the distal end 90 is formed as a right circular cylinder, but it should be understood that the distal end 90 can be formed into a different shape. The proximal end 92 is sized to be accommodated in the leg hole 36 of the bracket 12 with a small amount of clearance, which allows the second claw member 18 to move relative to the bracket 12 along the differential axis 30 relative to the axial movement, but limits the second claw member 18 relative to the bracket 12 in the rotational direction around the differential axis 30. In the example provided, the proximal end 92 is generally shaped as a trapezoidal prism (with concentric rather than parallel radial inner and outer surfaces), but it should be understood that the proximal end 92 can be formed into a shape different from that shown and described herein.
[0032] Back to Figures 3 to 5 The second jaw member 18 is axially movable along the differential axis 30 between a first position in which the second teeth 84 are disengaged from the first teeth 70 and a second position in which the second teeth 84 are engaged with the first teeth 70. If included, the circumferential guide surface 40 can guide the body 74 of the second jaw member 18 to help align the central axis of the second jaw member 18 with the differential axis 30.
[0033] exist Figure 3 Figure 7 to Fig.11 , the cam mechanism 20 has a plurality of cams 100 and a plurality of followers 102. Each of the cams 100 is fixedly coupled to (e.g., integrally formed on / with) a corresponding one of the legs 76, such as at the proximal end 92 at a location between the body 74 and the cylindrical distal end 90 of the corresponding one of the legs 76. Each of the followers 102 is fixedly coupled to (e.g., integrally formed with) the bracket 12 and disposed in the inner cavity 32. Each of the cams 100 can be engaged to a corresponding one of the followers 102.
[0034] Specific reference Figure 3 , the spring 22 biases the second jaw member 18 toward the first position along the differential axis 30. In the example shown, the spring 22 is a wave spring mounted on the hub 80 on the side gear 60 and received in a counterbore 110 formed in the body 74 of the second jaw member 18.
[0035] refer to Figure 3 and Figure 6, the electromagnet 24 may include a coil 120, a pole piece 122, and a plunger 124. The pole piece 122 surrounds the coil 120 on three sides (radially inner, radially outer, and axial end facing away from the cover 54) and defines a second frustoconical surface 130, which can be concentric with the first frustoconical surface 46 (i.e., the first frustoconical surface 46 and the second frustoconical surface 130 can be centered on the differential axis 30 and can adopt a common inner cone angle). The plunger 124 is fixedly coupled to the pole piece 122 and abuts the axial end surface 134 of the distal end 90 of the leg 76. In the example provided, the plunger 124 includes a tubular portion 136 and a flange 138. The tubular portion 136 is concentrically disposed around the differential axis 30, and one axial end of the tubular portion 136 is fixedly coupled to the pole piece 122. The flange 138 may extend radially outward from the tubular portion 136. The flange 138 abuts the axial end surface 134 of the distal end 90 of the leg 76. The electromagnet 24 is slidably disposed on the actuator hub 34. In the example provided, a bushing 140 is disposed between the outer hub surface 44 on the carrier 12 and the electromagnet 24. The bushing 140 allows the carrier 12 to rotate relative to the electromagnet 24 about the differential axis 30, and allows the electromagnet 24 to slide relative to the carrier 12 along the differential axis 30.
[0036] refer to Figure 3 and Figure 5 , the electromagnet 24 is operable in an energized state to generate a magnetic field that pulls the second frustoconical surface 130 on the pole piece 122 toward the first frustoconical surface 46 on the carrier 12, thereby correspondingly moving the second claw member 18 toward the second position. As the electromagnet 24 moves toward the carrier 12 along the differential axis 30, the plunger 124 that contacts the axial end surface 134 of the distal end 90 of the leg 76 correspondingly moves the second claw member 18, causing the second tooth 84 on the body 74 of the second claw member 18 to move toward the first tooth 70 on the first claw member 16. Because the second claw member 18 has limited ability to move relative to the carrier 12 about the differential axis 30 (this is due to the gap between the leg 76 in the carrier 12 and the edge of the leg hole 36), when the second claw member 18 is in the second position, the engagement of the second tooth 84 with the first tooth 70 similarly limits the movement of the first claw member 16 and the side gear 60 relative to the carrier 12 about the differential axis 30. In the example provided, when the second jaw member 18 is in the second position, the pole piece 122 is spaced apart from the circumferentially extending protrusion 38 (i.e., such that a gap or space exists between the first frustoconical surface 46 and the second frustoconical surface 130). However, it should be understood that the first frustoconical surface 46 and the second frustoconical surface 130 may be configured to contact each other when the second jaw member 18 is in the second position.
[0037] When the electromagnet 24 is operated to generate a magnetic field and the second claw member 18 is in the second position, at least a portion of the electromagnet 24 is disposed in the annular recess 48. Arrangement in this manner is advantageous because it makes the electronic locking differential 10 relatively more compact than some known configurations. In the particular example shown, a portion of the electromagnet 24 is disposed in the annular recess 48 when the electromagnet 24 is in the first position.
[0038] The cam mechanism 20 is configured to push the second claw member 18 toward the first claw member 16 when a torque greater than or equal to a first predetermined threshold is transmitted through the cam mechanism 20 in the first predetermined rotational direction. In this regard, the torque applied in the first predetermined rotational direction by the cam mechanism 20 between the carrier 12 and the side gear 60 causes a small amount of rotation of the cam 100 relative to the follower 102. The cam mechanism 20 is configured such that a thrust force is generated in response to the relative rotation between the cam 100 and the follower 102, which thrust force is directed into the second claw member 18 so as to push the second claw member 18 toward the first claw member 16 along the differential axis 30. Therefore, when a torque greater than or equal to the first predetermined threshold is transmitted through the cam mechanism 20 in the first predetermined rotational direction, the cam mechanism 20 helps to maintain the engagement of the second teeth 84 with the first teeth 70.
[0039] Alternatively, the cam mechanism 20 may be further configured to push the second claw member 18 toward the first claw member 16 when a torque greater than or equal to a second predetermined threshold is transmitted through the cam mechanism 20 in a second predetermined rotational direction opposite to the first predetermined rotational direction.
[0040] refer to Fig.12 A second electronic locking differential constructed in accordance with the teachings of the present disclosure is generally indicated by reference numeral 10a. The locking differential 10a is constructed similarly to the locking differential 10(a) except for the configuration of the leg apertures 36a in the bracket 12a, the configuration of the legs 76a of the second claw member 18a, and the cam mechanism 20a. Figure 1 ).
[0041] Additional references Fig.13 , the bracket 12a includes a cover 54a in which the leg holes 36a are formed. Each of the leg holes 36a may have a frustoconical portion 150 and a cylindrical portion 152. The frustoconical portion 150 is formed so that its base or wider end is disposed near the second claw member 18a. The cylindrical portion 152 intersects the narrower end of the frustoconical portion 150 and extends through the outer surface of the cover 54a.
[0042] refer to Fig.12 and Fig.14The legs 76a of the second claw member 18a are generally frustoconical in shape and are coupled to the body 74 of the second claw member 18a at their base or wide ends. Optionally, one or more flat surfaces 160 may be formed along the length of each of the legs 76a. Each of the flat surfaces 160 creates a corresponding interruption in the frustoconical circumferential surface of the legs 76a.
[0043] refer to Figure 12 to Figure 14 , the cam mechanism 20a includes a plurality of cams 100a and a plurality of followers 102a. Each of the cams 100a is fixedly coupled to (e.g., integrally formed on / with) a corresponding one of the legs 76a, and each of the followers 102a is fixedly coupled to (e.g., integrally formed on / with) a corresponding one of the legs 76a. In the example provided, each of the cams 100a is a frustoconical circumferential surface formed on a corresponding one of the legs 76a, and each of the followers 102a is a frustoconical portion 150 of a corresponding one of the leg holes 76a.
[0044] The foregoing description of the embodiments is provided for the purpose of illustration and description. It is not intended to be exhaustive or limit the present disclosure. The individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but where applicable, they are interchangeable and can be used in selected embodiments even if not specifically shown or described. The same situation can also be changed in many ways. Such changes should not be considered to depart from the present disclosure, and all such modifications are intended to be included within the scope of the present disclosure.
Claims
1. An electronic locking differential, comprising: a carrier rotatable about a differential axis, the carrier defining an inner cavity, an actuator hub, a plurality of leg holes, and a circumferentially extending protrusion, the actuator hub having an outer hub surface disposed concentrically about the differential axis, the leg holes being spaced apart about the differential axis, each of the leg holes intersecting the inner cavity, the circumferentially extending protrusion being coaxial with the outer hub surface and having a radially inner side defining a first frustoconical surface, wherein an annular recess is formed radially between the outer hub surface and the first frustoconical surface; a differential gear set received in the inner cavity, the differential gear set including side gears rotatable relative to the carrier about the differential axis; a first claw member fixedly coupled to the side gear, the first claw member having a first plurality of teeth; a second claw member received in the inner cavity, the second claw member having a body and a plurality of legs, the body defining a plurality of second teeth, each of the legs fixedly coupled to the body and received through an associated one of the leg apertures, wherein each of the legs has a distal end opposite the body, the second claw member being axially movable along the differential axis between a first position in which the second teeth are disengaged from the first teeth and a second position in which the second teeth are engaged with the first teeth; a cam mechanism having a plurality of cams and a plurality of followers, each of the cams being formed on a corresponding one of the legs at a position between the body and the distal end, each of the followers being fixedly coupled to the bracket and disposed in the inner cavity, each of the cams being engageable to a corresponding one of the followers; a spring biasing the second claw member toward the first position along the differential axis; as well as an electromagnet slidably disposed on the actuator hub, the electromagnet having a pole piece and a plunger fixedly coupled to the pole piece, the pole piece defining a second frustoconical surface, the plunger abutting an axial end surface of the distal end of the leg, the electromagnet being operable in an energized state to generate a magnetic field that pulls the second frustoconical surface on the pole piece toward the first frustoconical surface to move the second claw member toward the second position; wherein when the electromagnet is operated to generate the magnetic field and the second claw member is in the second position, at least a portion of the electromagnet is disposed in the annular recess; and The cam mechanism is configured to push the second claw member toward the first claw member when a torque greater than or equal to a first predetermined threshold is transmitted through the cam mechanism in a first predetermined rotational direction.
2. The electronic locking differential of claim 1 , wherein the cam mechanism is configured to push the second claw member toward the first claw member when a torque greater than or equal to a second predetermined threshold is transmitted through the cam mechanism in a second predetermined rotational direction, the second predetermined rotational direction being opposite to the first predetermined rotational direction.
3. The electronic locking differential of claim 1 further comprising a bushing mounted between the outer hub surface and the electromagnet. 4 . The electronic locking differential of claim 1 , wherein the differential gear set is a helical gear set including a plurality of differential pinions, each of the differential pinions being in meshing engagement with the side gears.
5. The electronic locking differential of claim 4, wherein the differential gear set includes a cross pin mounted on the carrier for rotation therewith, and wherein a pair of the differential pinions are rotationally mounted on the cross pin. 6 . The electronic locking differential of claim 1 , wherein the carrier includes a carrier body and a cover fixedly coupled to the carrier body, and wherein the circumferentially extending protrusion is formed on the cover.
7. The electronic locking differential of claim 6, wherein the follower is formed on the cover. 8 . The electronic locking differential of claim 1 , wherein the carrier defines a circumferential guide surface on which the body of the second claw member is guided. 9 . The electronic locking differential of claim 8 , wherein the carrier includes a carrier body and a cover fixedly coupled to the carrier body, and wherein the circumferential guide surface is formed on the cover.
10. The electronic locking differential of claim 1, wherein the plunger comprises a tubular portion and a flange, wherein the tubular portion is mounted on the pole piece and is concentrically disposed about the differential axis, and wherein the flange extends radially outward from the tubular portion.
11. The electronic locking differential of claim 1, wherein the distal end of each of the legs is shaped like a cylinder.
12. The electronic locking differential of claim 1 wherein each of said cams has a frustoconical cam surface that engages a frustoconical follower surface on a respective one of said followers.
13. The electronic locking differential of claim 12 wherein said frustoconical cam surface extends between said body of said second jaw member and said distal end of said leg.
14. The electronic locking differential of claim 12 wherein at least one flat surface is formed on each of said legs, said flat surface interrupting said frustoconical cam surface.