Three pinion differential

Abstract

A differential gear set includes cross-shafts secured at a center block. Pinions are mounted about respective ones of the cross-shafts. The center block holds the cross-shafts against movement along a longitudinal axis of the cross-shaft. The center block also may hold the cross-shafts against rotational movement relative to the cross-shaft. The center block may hold the cross-shafts spaced from each other. In an example, the differential gear set includes three identical cross-shafts bearing equal load during operation. In certain examples, the center block and pinions are axially mounted within a differential case while the cross-shafts are radially mounted.

Description

Attorney Docket No. 15720.1150WOU1THREE PINION DIFFERENTIALCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of Indian Provisional Application No. 202411075035, filed October 04, 2024, titled “Three Pinion Differential,” the disclosure of which is hereby incorporated herein 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 gear case; and a differential gear set including a center block and cross-shaft assembly connecting first and second side gears.

[0005] In certain implementations, the center block and cross-shaft assembly includes: a center block; a plurality of cross-shafts mounted to the center block; a plurality of pinions. Each cross-shaft is rotationally fixed relative to the center block. Each pinion is mounted about a respective one of the cross-shafts. In certain examples, the center block and cross-shaft assembly includes three cross-shafts.Attorney Docket No. 15720.1150WOU1

[0006] In certain implementations, the gear case defines apertures in radial alignment with the cross-shafts to enable radial insertion of the cross-shafts into the center block from an exterior of the gear case.

[0007] In certain implementations, the differential arrangement is assembled by axially inserting a plurality of pinions into an interior of the gear case; axially inserting a center block into the interior of a gear case; and radially inserting a plurality of cross-shafts from an exterior of the gear case, through respective apertures defined in the gear case, through respective ones of the pinions, and into the center block.

[0008] In certain examples, the method also includes securing the cross-shafts at the center block by axially inserting a plurality of retention members.

[0009] 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

[0010] 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:

[0011] FIG. 1 is a perspective view of an example locking differential configured in accordance with the principles of the present disclosure;

[0012] FIG. 2 is an axial cross-sectional view of the locking differential of FIG. 1;

[0013] FIG. 3 shows an example cross-shaft and center block assembly suitable for use in the locking differential of FIG. 1;

[0014] FIG. 4 shows the center block and cross-shaft assembly of FIG. 2 disposed within a gear case of the locking differential of FIG. 1;

[0015] FIG. 5 is a perspective view of an example center block suitable for use with the center block and cross-shaft assembly of FIG. 3;

[0016] FIG. 6 is a perspective view of an example cross-shaft suitable for use with the center block and cross-shaft assembly of FIG. 3;

[0017] FIG. 7 is a perspective view of a transverse cross-section taken through the center block and cross-shaft assembly and gear case of FIG. 4 with the cross-shafts removed for ease in viewing;Attorney Docket No. 15720.1150WOU1

[0018] FIG. 8 is an end view of the center block and cross-shaft assembly and gear case of FIG. 7 with the cross-shafts shown;

[0019] FIG. 9 is a perspective view of an example end cap of the locking differential of FIG. 1;

[0020] FIG. 10 is an enlarged view of a first portion of FIG. 9 showing a radial lubrication pathway; and

[0021] FIG. 11 is an enlarged view of a second portion of FIG. 9 showing an axial lubrication pathway.DETAILED DESCRIPTION

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

[0023] FIGS. 1 and 2 show a locking differential 100 for a vehicle. The locking differential 100 includes a gear housing 102 (e.g., a gear case 104 and an end cap 106) 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 arrangement 105 of the gear housing 102. For example, the gear case 104 and / or the end cap 106 may define the flange arrangement 105. The gear housing 102 defines annular hub portions 108 and 110 at which left and right axle shafts are inserted. 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 gear housing 102 defines a gear chamber 112 in which a differential gear set 114 is disposed.

[0024] The differential gear set 114 includes first and second side gears 126, 128 connected by pinions 124. Each side gear 126, 128 connects to one of the left and right axle shafts. A locking arrangement 118 that can be transitioned between a locking configuration and a non-locking configuration. When disposed in a locking configuration, the locking arrangement 118 inhibits independent rotation of the side gear 126 from the gear housing 102. When disposed in a non-locking configuration, the locking arrangement 118 allows independent rotation of the side gear 126 relative to the gear housing 102 (e.g., along the longitudinal axis L of the housing 102). In certain implementations, the locking arrangement 118 includes an armature 119 and a locking collar 122 spaced apart by one or more pins 124 (e.g., pull rods). In some implementations, the locking differential 100 is transitionedAttorney Docket No. 15720.1150WOU1 between locked and unlocked modes manually by a user. In other implementations, the locking differential 100 is transitioned between locked and unlocked modes automatically (e.g., by a microprocessor of the vehicle based on a sensed operational condition of the vehicle).

[0025] In accordance with certain aspects of the disclosure, the differential gear set 114 includes a center block and cross-shaft assembly 130 connecting the first and second side gears 126, 128. The center block and cross-shaft assembly 130 includes a center block 134, cross-shafts 132 extending outwardly from the center block 134, and pinions 124 mounted about the cross-shafts 132. Each cross-shaft 132 is independently mounted to the center block 134 rotationally fixed relative to the center block 134. Each pinion 124 is configured to rotate about a respective one of the cross-shafts 132. In certain examples, a respective pin 136 (e.g., spring pin) extends through the center block 134 and each cross-shaft 132 to hold the cross-shaft 132 in position relative to the center block 134.

[0026] In certain implementations, the cross-shafts 132, center block 134, and pinions 124 rotate with the gear housing 102 about the longitudinal axis L. In certain implementations, the rotation causes an equal load to be applied to each of the cross-shafts 132. The loads on the cross-shafts 132 are equal because the cross-shafts 132 have a common shape, a common size, and a common mounting mechanism with each other. In an example, the cross-shafts 132 are identical to each other. In certain examples, the differential gear set 114 includes a plurality of separate cross-shafts 132 that are identical to each other. In certain examples, the differential gear set 114 includes more than two identical cross-shafts 132. In an example, the differential gear set 114 includes three identical cross-shafts 132.

[0027] FIG. 5 shows an example implementation of a center block 134 suitable for use in the center block and cross-shaft assembly 130. The center block 134 includes a core body 140 extending along a width between a first end 141 and a second end 143. The core body 140 includes a circumferential wall 145 extending between the first and second ends 141, 143. In certain examples, the first and second ends 141, 143 are flat. In certain implementations, the ends 141, 143 of the core body 140 define retention apertures 152 to receive the pins 136.

[0028] Three mounting stations 142 are disposed along the circumferential wall 145. In the example shown, three mounting stations 142 A, 142B, 142C are spaced evenly along the circumferential wall 145. Each mounting station 142 defines an aperture 144 leading towards a center of the core body 140. Each aperture 144 is configured to receive a respective one of the cross-shafts 132. In certain examples, each mounting station 142 also defines a pinionAttorney Docket No. 15720.1150WOU1 engagement surface 146 around the aperture 144. In an example, the pinion engagement surface 146 is flat. In certain examples, a respective pinion 124 seats on the pinion engagement surface 146 (e.g., see FIG. 4).

[0029] In certain implementations, the core body 140 defines a lubrication passage 150 through which lubricant (e.g., oil) flows. In the example shown, the lubrication passage 150 extends between the opposite ends 141, 143. In an example, the lubrication passage 150 extends along a central axis of the core body 140. In another example, the lubrication passage 150 extends radially through the core body 140 between two of the apertures 144. In certain examples, a radial lubrication passage may extend radially outward through the core body 140 between each pair of apertures 144. The lubricant can enter the gear case 102 through one or more windows 107. For example, lubricant can enter the gear chamber 112 through the windows 107 at one side of the center block and cross-shaft assembly 130 and lubricate engagement surfaces of the pinions 124 and the second side gear 128. The lubricant also may pass through the lubrication passage 150 to an interior of the center block to lubricate the ends of the cross-shafts 132. In certain examples, the lubricant may flow through the lubrication passage 150 to an opposite side of the center block and cross-shaft assembly 130 to lubricate the engagement surfaces of the pinions 124 and first side gear 126.

[0030] FIG. 6 shows an example implementation of a cross-shaft 132. The cross-shaft 132 includes a shaft body 160 extending along a length between a first end 162 and a second end 164. The first end 162 is configured to fit through the aperture 144 of one of the mounting stations 142. In certain examples, the first end 162 is flat. In certain examples, the first ends 162 of the cross-shafts 132 are radially spaced from the longitudinal axis of the center block 134. For example, the first ends 162 of the cross-shafts 132 may be radially offset from the lubrication passage 150. In certain examples, flat surfaces 168 angle away from the first end 162 to avoid interference with each other (e.g., see FIG. 8).

[0031] In certain implementations, each cross-shaft 132 includes a flat surface 166. In certain examples, the cross-shaft 132 includes oppositely disposed flat surfaces 166. The flat surfaces face interior flat surfaces 148 of the center block 134. In certain examples, engagement between the flat surfaces 166, 148 inhibits rotation of the cross-shaft 132 relative to the center block 134. In certain examples, engagement between the flat surfaces 166, 148 keys the cross-shaft 132 to be inserted into the center block 134 at a predetermined rotational orientation. In certain implementations, an aperture 165 extends through each cross-shaft 132. In certain examples, the aperture 162 extends between the opposite flat surfaces 166. In certain examples, the aperture 162 of each cross-shaft 132 aligns with one of the retention aperturesAttorney Docket No. 15720.1150WOU1152 defined through the center block 134. Accordingly, the flat surfaces 166, 148 key the cross-shaft 132 to mount to the center block 134 so that the retention apertures 165, 152 align.

[0032] In certain implementations, the size of the gear chamber 112 inhibits assembly of the center block and cross-shaft assembly 130 therein. In certain examples, the gear chamber 112 is sufficiently small that the pinions 124 seat against the center block 134 (e.g., see FIG. 4). Referring to FIG. 7, the center block and cross-shaft assembly 130 is assembled by first positioning the pinions 124 at respective mounting positions within the gear chamber 112. For example, the pinions 124 can be axially inserted into the gear chamber 112 and radially aligned with respective openings 109 defined through the gear housing 102. The center block 134 is positioned between the pinions 124 (e.g., at a central portion of the gear chamber 112). For example, the center block 134 can be axially inserted into the gear chamber 112.

[0033] Each cross-shaft 132 is inserted radially (e.g., see radial directions DI, D2, D3 of FIG. 7) through one of the openings 109 in the gear housing 102, through a respective one of the pinions 124, and into the aperture 144 of a respective one of the mounting stations 142 at the center block 134. The flats surfaces 166, 148 ensure correct rotational alignment between the cross-shafts 132 and the center block 134. The pins 136 are then axially inserted through the retention apertures 152, 165 to lock the cross-shafts 132 at the center block 134. Each pin 136 inhibits the respective cross-shaft 132 from being pulled out of the respective mounting station 142 of the center block 134 (e.g., see FIG. 8).

[0034] Referring now to FIGS. 9-11, the gear housing 102 may include additional lubrication pathways to reach the various internal components. In certain implementations, the end cap 106 defines one or more of the additional pathways. In certain examples, the end cap 106 defines a first lubrication pathway 172 leading radially into an interior of the gear housing 102. In certain examples, the end cap 106 defines a second lubrication pathway 174 leading axially into the interior of the gear housing 102. In certain examples, the first and / or second lubrication pathways 172, 174 enable lubricant to reach engagement surfaces between the first side gear 126 and the end cap 106 (or other portion of the gear housing 102). In certain examples, the first and / or second lubrication pathways 172, 174 enable lubricant to reach engagement surfaces between the first side gear 126 and the locking collar 122.

[0035] In certain implementations, the end cap 106 includes an annular wall 170 disposed between a radial flange 171 and the annular hub portion 108. As shown in FIGS. 9 and 10, the annular wall 170 may define one or more apertures 176 leading radially into the interior of the gear housing 102 to define the first lubrication pathway 172. The apertures 176 are disposed along a circumference of the annular wall 170. In certain examples, the apertures 176 areAttorney Docket No. 15720.1150WOU1 evenly spaced along the circumference. In certain examples, the apertures 176 are elongated along the circumference of the annular wall 170.

[0036] In certain implementations, the second lubrication pathway 174 includes one or more apertures 178 leading axially into the interior of the gear housing 102. For example, the apertures 178 may be defined on a stepped surface between the annular wall 170 and the annular hub portion 108. In certain examples, channels 180 extend between pairs of the apertures 178 (e.g., see FIG. 11). The channel 180 may guide lubricant to the apertures 178.

[0037] 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

Attorney Docket No. 15720.1150WOU1What is claimed is:

1. A differential arrangement comprising: a gear case defining an interior; a differential gear set disposed within the interior of the gear case, the differential gear set including: a first side gear; a second side gear; a center block and cross-shaft assembly connecting the first and second side gears, the center block and cross-shaft assembly including: a center block; a plurality of cross-shafts mounted to the center block, each cross-shaft being rotationally fixed relative to the center block; and a plurality of pinions, each pinion being mounted about a respective one of the cross-shafts.

2. The differential arrangement of claim 1, wherein the gear case defines apertures in radial alignment with the cross-shafts to enable assembly of the cross-shafts into the center block.

3. The differential arrangement of claim 1, further comprising a plurality of retention members that hold the cross-shafts at the center block.

4. The differential arrangement of claim 3, wherein the retention members are configured to be axially inserted through the center block and cross-shafts.

5. The differential arrangement of claim 3, wherein each cross-shaft defines a flat surface through which a respective one of the retention members passes.

6. The differential arrangement of claim 1, wherein the center block defines an axis and defines a plurality of insertion apertures facing radially outwardly from the axis; wherein the cross-shafts extend into the insertion apertures.Attorney Docket No. 15720.1150WOU17. The differential arrangement of claim 6, wherein the center block defines a lubrication passage.

8. The differential arrangement of claim 7, wherein the lubrication passage extends through the center block along the axis.

9. The differential arrangement of claim 7, wherein the lubrication passage extends radially through the center block.

10. The differential arrangement of claim 1, wherein the gear case includes a gear housing and an end cap, and wherein the end cap defines a lubrication pathway.

11. The differential arrangement of claim 10, wherein the lubrication pathway is a radial pathway.

12. The differential arrangement of claim 11, wherein the end cap also defines an axial lubrication pathway.

13. A method of assembling a differential arrangement, the method comprising: axially inserting a plurality of pinions into an interior of the gear case; axially inserting a center block into the interior of a gear case, the center block being positioned between the pinions; and radially inserting a plurality of cross-shafts from an exterior of the gear case, through respective apertures defined in the gear case, through respective ones of the pinions, and into the center block.

14. The method of claim 10, further comprising securing the cross-shafts at the center block by axially inserting a plurality of retention members.

15. The method of claim 10, further comprising holding the center block within the gear case using a lubrication passage of the center block.Attorney Docket No. 15720.1150WOU116. A differential arrangement comprising: a gear case defining an interior; a differential gear set disposed within the interior of the gear case, the differential gear set including: a first side gear; a second side gear; and a pinion assembly connecting the first and second side gears, the pinion assembly including a plurality of pinions and a plurality of cross-shafts, each crossshaft extending through and supporting a respective one of the pinions, wherein the cross-shafts are configured for equal load sharing during rotation of the gear case.

17. The differential arrangement of claim 16, wherein each of the cross-shafts extends radially outward from a center block.

18. The differential arrangement of claim 17, wherein the cross-shafts are rotationally fixed at the center block.

19. The differential arrangement of claim 16, wherein each of the cross-shafts extends radially inwardly from a first end to a second end, and wherein the second ends of the crossshafts are spaced from each other.

20. The differential arrangement of claim 16, wherein the cross-shafts are identical to each other.

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