Limited slip differentials with centrifugal spring mass actuator for vehicle powertrains

Patent metadata

Field	Value
Publication number	US-10066722-B2
Application number	US-201715398748-A
Country	US
Kind code	B2
Filing date	Jan 5, 2017
Priority date	Jan 5, 2017
Publication date	Sep 4, 2018
Grant date	Sep 4, 2018

Abstract

Limited slip differentials (LSD), methods for making and methods for using such LSDs, and motor vehicles employing an LSD. An LSD for a motor vehicle includes a differential casing that drivingly connects to the driveshaft, and two side gears rotatably mounted inside the casing. Each side gear drivingly connects to a respective axle shaft. One or both side gears includes a respective friction surface. One or more pinion gears are mounted inside the casing and meshingly engaged with the side gears. One or more friction plates are movably mounted inside the casing to selectively engage with and disengage from a friction surface. A centrifugal spring mass, which is mounted to one of the pinion gears, includes circumferentially spaced springs that expand responsive to a predetermined disparity in rotational speed between the side gears and thereby urge the friction plate(s) into engagement with the friction surface(s).

First claim

What is claimed:

1. A limited slip differential for a motor vehicle, the motor vehicle including a prime mover operatively connected to a driveshaft, and a pair of axle shafts each operatively connected to a respective one of a pair of road wheels, the limited slip differential comprising:
a differential casing configured to drivingly connect to the driveshaft;
a pair of side gears rotatably mounted inside the differential casing and each configured to drivingly connect to a respective one of the axle shafts, a first of the side gears including a first friction surface;
a pair of pinion gears mounted inside the differential casing and meshingly engaged with the pair of side gears;
a first friction plate movably mounted inside the differential casing and configured to selectively engage with and disengage from the first friction surface; and
a centrifugal spring mass mounted to a first of the pinion gears for common rotation therewith, the centrifugal spring mass including a plurality of circumferentially spaced springs configured to expand in response to a predetermined disparity in rotational speed between the side gears and thereby urge the first friction plate into engagement with the first friction surface.

2. The limited slip differential of claim 1 , wherein a second of the side gears includes a second friction surface, the limited slip differential further comprising a second friction plate movably mounted inside the differential casing and configured to selectively engage with and disengage from the second friction surface.

3. The limited slip differential of claim 1 , further comprising a second centrifugal spring mass mounted to a second of the pinion gears for common rotation therewith, the second centrifugal spring mass including a second plurality of circumferentially spaced springs configured to expand in response to the predetermined disparity in rotational speed between the side gears and thereby urge the first friction plate into engagement with the first friction surface.

4. The limited slip differential of claim 1 , further comprising:
a pinion shaft rotatably mounting the pinion gears to the differential casing;
a sleeve shaft circumscribing the pinion shaft and mounting the centrifugal spring mass to the first pinion gear.

5. The limited slip differential of claim 4 , wherein a first end of the sleeve shaft is rigidly attached to the first pinion gear, and wherein the centrifugal spring mass includes a disc mounted to a second end of the sleeve shaft opposite the first end.

6. The limited slip differential of claim 1 , further comprising a return mechanism biasing the first friction plate away from the first friction surface.

7. The limited slip differential of claim 6 , wherein the return mechanism includes a helical spring or leaf spring coupled to the first friction plate.

8. The limited slip differential of claim 1 , further comprising a slide rail slidably mounting the first friction plate to the differential casing.

9. The limited slip differential of claim 1 , wherein the centrifugal spring mass further comprises a plurality of masses interconnecting the plurality of circumferentially spaced springs.

10. The limited slip differential of claim 1 , wherein each of the circumferentially spaced springs includes a spring stiffness configured such that the springs expand sufficiently to urge the first friction plate into engagement with the first friction surface and thereby lock the side gears together only in response to the rotational speed between the side gears exceeding the predetermined disparity.

11. The limited slip differential of claim 1 , wherein the side gears and the pinion gears each comprise a respective bevel gear.

12. The limited slip differential of claim 1 , further comprising a driving ring gear mounted to the rotatable differential casing for common rotation therewith.

13. The limited slip differential of claim 1 , wherein the first friction surface is mounted on or integrally formed with the first side gear.

14. A motor electric vehicle, comprising:
a vehicle chassis frame;
a powertrain system mounted to the vehicle chassis frame and including a prime mover, a driveshaft, and a power transmission connecting the prime mover to the driveshaft;
a final drive system mounted to the vehicle chassis frame and including a plurality of road wheels and a plurality of axle shafts each drivingly connected to a respective one of the road wheels; and
a limited slip differential including:
a differential casing rotatably mounted to the vehicle chassis frame and drivingly connected to the driveshaft for common rotation therewith;
a pair of bevel side gears rotatably mounted inside the differential casing and each drivingly connected to a respective one of the axle shafts for common rotation, each of the side gears including a respective friction surface;
a pair of bevel pinion gears rotatably mounted inside the differential casing and meshingly engaged with the pair of side gears;
a pair of friction plates slidably mounted inside the differential casing and each configured to slide into and out of friction engagement with a respective one of the friction surfaces of the side gears; and
a pair of centrifugal spring masses each mounted to a respective one of the pinion gears for common rotation therewith, each centrifugal spring mass including a respective plurality of circumferentially spaced springs, the springs being configured to expand in response to a predetermined disparity in rotational speed between the side gears and thereby urge the friction plates into engagement with the friction surfaces such that the side gears lock to the differential casing and the axle shafts rotate substantially in unison.

15. A method of assembling a limited slip differential for a motor vehicle, the motor vehicle including a prime mover operatively connected to a driveshaft, and a pair of axle shafts each operatively connected to a respective one of a pair of road wheels, the method comprising:
rotatably mounting a pair of side gears inside a differential casing, the differential casing being configured to drivingly connect to the driveshaft, and each of the side gears being configured to drivingly connect to a respective one of the axle shafts, a first of the side gears including a first friction surface;
rotatably mounting a pair of pinion gears inside the differential casing such that the pinion gears meshingly engage with the side gears;
movably mounting a first friction plate inside the differential casing such that the first friction plate selectively engages with and disengages from the first friction surface; and
mounting a centrifugal spring mass to a first of the pinion gears for common rotation therewith, the centrifugal spring mass including a plurality of circumferentially spaced springs configured to expand in response to a predetermined disparity in rotational speed between the side gears and thereby urge the first friction plate into engagement with the first friction surface.

16. The method of claim 15 , wherein a second of the side gears includes a second friction surface, the method further comprising movably mounting a second friction plate inside the differential casing such that the second friction plate selectively engages with and disengages from the second friction surface.

17. The method of claim 15 , further comprising mounting a second centrifugal spring mass to a second of the pinion gears for common rotation therewith, the second centrifugal spring mass including a second plurality of circumferentially spaced springs co

Assignees

• Gm Global Tech Operations Llc

Inventors

• Dewangan Yogesh Kumar
• Ch Bhaskara K
• Ryali Lokaditya

Classifications

• F16D43/08

  the pressure ring actuating friction plates, cones or similar axially-movable friction surfaces · CPC title

• F16H48/22 Primary

  using friction clutches or brakes · CPC title

• F16D13/42

  with means for increasing the effective force between the actuating sleeve or equivalent member and the pressure member · CPC title

• F16H2048/382

  Methods for manufacturing differential gearings · CPC title

• F16H48/08

  comprising bevel gears · CPC title