US-12618458-B2 - Limited slip differential unit

Abstract

Systems are provided for a limited slip differential (LSD). The LSD comprises a two-piece differential case, an intermediate floating piece positioned in an interior of the two-piece differential case and configured to slide axially therein. The LSD, further comprises a first side gear and a second side gear meshed with gears of the intermediate floating piece, a first disc spring mounted on the first side gear and a second disc spring mounted on the second side gear, a first clutch pack mounted on the first side gear and positioned between the first disc spring and a lip of the first side gear, and a second clutch pack mounted on the second side gear and positioned between the second disc spring and a lip of the second side gear, and a shim mounted on the second side gear and positioned axially between the second disc spring and the two-piece differential case.

Inventors

• Sudatta Karmarkar
• Idris POONAWALA
• Pradip Jasud

Assignees

• DANA ITALIA S.R.L.

Dates

Publication Date

20260505

Application Date

20241224

Claims (17)

1. 1 . A limited slip differential, comprising: a two-piece differential case including: a first differential case piece with a gear coupled thereto; and a second differential case piece removably coupled to the first differential case piece; an intermediate floating piece positioned radially inward from the second piece and including a pin and planet gears rotatably coupled to the pin, wherein the intermediate floating piece is coupled to the differential case via splines that enable the intermediate floating piece to slide axially in relation to the differential case; a first side gear and a second side gear meshed with each of the planet gears; a first disc spring mounted on the first side gear and a second disc spring mounted on the second side gear; a first clutch pack mounted on the first side gear and positioned between the first disc spring and a lip of the first side gear, and a second clutch pack mounted on the second side gear and positioned between the second disc spring and a lip of the second side gear; and a shim mounted on the second side gear and positioned axially between the second disc spring and the two-piece differential case; wherein each of the first side gear and the second side gear are configured to exert axial force in an outward direction and activate a respective clutch pack of the first clutch pack and the second clutch pack in response to a respective wheel of a first drive wheel and a second drive wheel experiencing resistance that is greater than a preload applied to the respective clutch pack of the first clutch pack and the second clutch pack by a respective disc spring of the first disc spring and the second disc spring.
2. 2 . The limited slip differential of claim 1 , wherein the gear is mounted on the first differential case piece.
3. 3 . The limited slip differential of claim 1 , wherein the intermediate floating piece is configured to provide a reaction surface for each of the first clutch pack and the second clutch pack.
4. 4 . The limited slip differential of claim 1 , wherein each of the first clutch pack and the second clutch pack comprise alternating friction plates and reaction plates.
5. 5 . The limited slip differential of claim 1 , wherein the intermediate floating piece has a spherical radius.
6. 6 . The limited slip differential of claim 1 , wherein the intermediate floating piece is formed of bronze.
7. 7 . A driveline, comprising: a power source having a power source output shaft; a first reduction comprising an input pinion coupled to and driven by the power source output shaft and a first intermediate gear mounted on an intermediate shaft and meshed with the input pinion; a second reduction comprising a second intermediate gear driven by the first intermediate gear and an output gear driven by the second intermediate gear; and a limited slip differential coupled to the output gear, the limited slip differential comprising: a two-piece differential case including: a first differential case piece with the output gear coupled thereto; and a second differential case piece removably coupled to the first differential case piece; an intermediate floating piece positioned radially inward from the second piece and including a pin and planet gears rotatably coupled to the pin, wherein the intermediate floating piece is coupled to the differential case via splines that enable the intermediate floating piece to slide axially in relation to the differential case; a first side gear and a second side gear meshed with each of the planet gears; a first disc spring mounted on the first side gear and a second disc spring mounted on the second side gear; a first clutch pack mounted on the first side gear and positioned between the first disc spring and a lip of the first side gear; a second clutch pack mounted on the second side gear and positioned between the second disc spring and a lip of the second side gear; and a shim mounted on the second side gear and positioned axially between the second disc spring and the two-piece differential case; wherein each of the first side gear and the second side gear are configured to exert axial force in an outward direction and activate a respective clutch pack of the first clutch pack and the second clutch pack in response to a respective wheel of a first drive wheel and a second drive wheel experiencing resistance that is greater than a preload applied to the respective clutch pack of the first clutch pack and the second clutch pack by a respective disc spring of the first disc spring and the second disc spring.
8. 8 . The driveline of claim 7 , further comprising a first axle shaft coupled to the first drive wheel and to the first side gear of the limited slip differential, and a second axle shaft coupled to the second drive wheel and to the second side gear of the limited slip differential.
9. 9 . The driveline of claim 8 , further comprising ball bearings on each of the input pinion, the first intermediate gear, the second intermediate gear, and the two-piece differential case that enable rotation independent of a drive gear box housing.
10. 10 . The driveline of claim 8 , wherein the intermediate floating piece is configured to move axially in line with the first axle shaft and the second axle shaft.
11. 11 . The driveline of claim 7 , wherein the power source is an electric machine.
12. 12 . The driveline of claim 7 , wherein the power source is an internal combustion engine.
13. 13 . A driveline, comprising: a first axle shaft coupled to a first drive wheel; a second axle shaft coupled to a second drive wheel; a power source configured to distribute torque to the first drive wheel and the second drive wheel via the first axle shaft and the second axle shaft, respectively; and a limited slip differential configured to control distribution of torque between the first drive wheel and the second drive wheel in response to resistance experienced by each of the first drive wheel and the second drive wheel, the limited slip differential comprising: a differential case including: a first differential case piece with a gear coupled thereto; and a second differential case piece removably coupled to the first differential case piece; an intermediate floating piece positioned radially inward from the second piece and including a pin and planet gears rotatably coupled to the pin, wherein the intermediate floating piece is coupled to the differential case via splines that enable the intermediate floating piece to slide axially in relation to the differential case; a first clutch pack and a first disc spring mounted on a first side gear that is meshed with the intermediate floating piece and coupled to the first axle shaft; and a second clutch pack and a second disc spring mounted on a second side gear that is meshed with the intermediate floating piece and coupled to the second axle shaft; wherein each of the first side gear and the second side gear are configured to exert axial force in an outward direction and activate a respective clutch pack of the first clutch pack and the second clutch pack in response to a respective wheel of the first drive wheel and the second drive wheel experiencing resistance that is greater than a preload applied to the respective clutch pack of the first clutch pack and the second clutch pack by a respective disc spring of the first disc spring and the second disc spring.
14. 14 . The driveline of claim 13 , wherein the intermediate floating piece comprises the planet gears mounted on the pin, and wherein the first side gear and the second side gear are meshed with the planet gears.
15. 15 . The driveline of claim 13 , wherein the splines in the intermediate floating piece are position axially inboard from the second clutch pack.
16. 16 . The driveline of claim 13 , further comprising a shim removably mounted on the second side gear and positioned axially between the second disc spring and the differential case, the shim configured to provide a preload to the second axle shaft.
17. 17 . The driveline of claim 13 , wherein the limited slip differential is configured to direct a lesser amount of torque from the power source to a drive wheel of the first drive wheel and the second drive wheel that is experiencing less resistance, compared to the drive wheel that is experiencing more resistance.

Description

CROSS REFERENCE TO RELATED APPLICATION The present application claims priority to U.S. Provisional Application No. 63/618,065, entitled “LIMITED SLIP DIFFERENTIAL UNIT”, and filed on Jan. 5, 2024. The entire contents of the above-listed application are hereby incorporated by reference for all purposes. TECHNICAL FIELD A limited slip differential configured to enable torque distribution among drive wheels experiencing different amounts of tractive resistance and prevent drive wheel roll when parked on a grade. BACKGROUND AND SUMMARY Axle assemblies are adapted to transmit rotational power from a rotational power source of a vehicle to the wheels thereof. Typically, an axle assembly includes a differential assembly that is rotatably supported within a non-rotating housing (e.g., carrier). The differential is connected between an input drive shaft extending from the rotational power source/transmission and a pair of output axle shafts extending to the vehicle wheels. The axle shafts are contained in respective non-rotating beam housing portions, which are secured to a central housing. Thus, rotation of the differential by the drive shaft causes corresponding rotation of the axle shafts. The central housing and the beam housing portions form an axle housing for these drive train components of the axle assembly, with the differential and the axle shafts supported for rotation therein. A limited slip differential (LSD) is a type of differential configured to increase traction of one or more drive wheels of an axle that is rotatably driven by the LSD. The LSD detects differences in tractive resistance experienced by different drive wheels and adjusts a distribution of torque from a power source to the drive wheels, such that more torque is delivered to a drive wheel experiencing greater tractive resistance (e.g., the drive wheel with more grip). Existing LSDs may not include sufficient space for differential gears due to a clutch pack of the LSD being preloaded to achieve a desired performance of the LSD. Disc springs used to preload the clutch pack are selected based on preload calculations. In particular, a spring size of the disc springs is selected based on spatial constraints and an ability of the disc springs to achieve a desired preload. Further, in a conventional LSD, a cavity in which the clutch pack is positioned is directly machined in a differential housing. Since a spatial constraint of the cavity is based on an outer diameter of the differential, machining the cavity based on a size of the clutch pack may demand spherical machining of satellite gears of the LSD. Additionally, a footprint and a weight of a conventional LSD may exceed space and weight availability of a vehicle that frequently operates on low-traction driving surfaces, such as a golf cart driving on grass or turf. The inventors herein have recognized these and other issues with such systems and herein present a LSD that at least partially addresses these challenges. In one embodiment, a LSD comprises a two-piece differential case, an intermediate floating piece positioned in an interior of and coupled to the two-piece differential case via splines that enable the intermediate floating piece to slide axially, the intermediate floating piece including a sleeve assembly with planet gears and a pin positioned therein, a first side gear and a second side gear meshed with each of the planet gears, a first disc spring mounted on the first side gear and a second disc spring mounted on the second side gear, a first clutch pack mounted on the first side gear and positioned between the first disc spring and a lip of the first side gear, and a second clutch pack mounted on the second side gear and positioned between the second disc spring and a lip of the second side gear, and a shim mounted on the second side gear and positioned axially between the second disc spring and the two-piece differential case. The LSD described herein may be integrated in a driveline comprising a drive gear box housing, a power source having a power source output shaft, a first reduction comprising an input pinion mounted on the power source output shaft and a first intermediate gear mounted on an intermediate shaft and meshed with the input pinion, and a second reduction comprising a second intermediate gear mounted on the intermediate shaft and an output gear meshed with the second intermediate gear, where the first reduction and the second reduction transfer power from the power source to the LSD to be distributed to drive wheels. It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvant