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Electronically-controlled coupling for all-wheel drive system

Imported: 24 Feb '17 | Published: 06 Jan '04

Fred C. Porter

USPTO - Utility Patents

Abstract

A drive axle for an all-wheel drive vehicle includes an adaptively controlled first hydraulic coupling for providing front-to-rear torque transfer control and a passively controlled second hydraulic coupling for providing side-to-side limited slip and torque biasing control. The drive axle is contained with a common housing and communicates with a tractor control system to actively control actuation of the first hydraulic coupling based on the operating characteristics of the vehicle as detected by suitable sensors.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

Further objects, features and advantages of the present invention will become readily apparent from the following detailed specification and the appended claims which, in conjunction with the drawings, set forth the best mode now contemplated for carrying out the invention. Referring to the drawings:

FIG. 1 is a schematic view of a motor vehicle drivetrain equipped with a secondary drive axle assembly constructed in accordance with the present invention;

FIG. 2 is a sectional view of the secondary drive axle assembly of the present invention;

FIG. 3 is a sectional view of an on-demand hydraulic coupling associated with the secondary drive axle assembly;

FIG. 4 is an enlarged partial view taken from FIG. 3 showing components of the hydraulic coupling in greater detail;

FIGS. 5 and 6 are schematic diagrams illustrating a hydraulic control circuit associated with the on-demand hydraulic coupling shown in FIG. 3;

FIG. 7 is a sectional view of a differential drive module associated with the secondary drive axle of the present invention; and

FIG. 8 is a schematic diagram illustrating a hydraulic circuit for an on-demand hydraulic coupling equipped with a variable displacement pump and a torque limiting feature.

Claims

1. A power transfer assembly for transferring drive torque from a vehicular powertrain to a pair of wheels comprising:

2. The power transfer assembly of claim 1 wherein said control unit includes logic for controlling actuation of said control valve in response to predetermined relationships related to the speed difference between said input member and said output member.

3. The power transfer assembly of claim 2 wherein said logic further includes a sub-routine to compensate for changes in fluid viscosity based on the fluid temperature detected by said first temperature sensor.

4. The power transfer assembly of claim 3 wherein said control unit is adapted to open said control valve and release said clutch pack when the fluid temperature detected by said second temperature sensor exceeds a predetermined value.

5. The power transfer assembly of claim 1 wherein said output member includes a differential assembly operably interconnecting the pair of wheels.

6. The power transfer assembly of claim 1 wherein said fluid control system further includes a pump driven by said input member for supplying fluid to said actuator, and wherein said control valve is operably disposed between said pump and said actuator.

7. The power transfer assembly of claim 6 wherein said pump is a gerotor pump adapted to generate a fluid pumping action in response to speed differentiation between said input and output members.

8. The power transfer assembly of claim 1 further comprising a drive module having a drive case driven by said output member, a pair of axleshafts adapted for connection to the pair of wheels, and a differential assembly interconnecting said drive case to said axleshafts to facilitate speed differentiation between said axleshafts.

9. The power transfer assembly of claim 8 further comprising a second torque coupling operably disposed between said drive case and one of said axleshafts.

10. A power transfer assembly for transferring drive torque from a vehicular powertrain to a pair of wheels, comprising:

11. The power transfer assembly of claim 10 further comprising a drive module for transferring drive torque from said pinion shaft to the wheels, said drive module including a drive case driven by said pinion shaft and a differential unit interconnecting said drive case to the wheels.

12. The power transfer assembly of claim 10 wherein said control valve has an inlet in communication with said pump outlet, a first outlet in communication with said piston chamber, and a second outlet in communication with a clutch chamber within which said clutch pack is disposed.

13. The power transfer assembly of claim 12 wherein said second temperature sensor is disposed between said first outlet of said control valve and said piston chamber.

14. The power transfer assembly of claim 12 wherein said second temperature sensor is disposed between said second outlet of said control valve and said clutch chamber.

15. The power transfer assembly of claim 10 wherein said controller includes logic for controlling actuation of said control valve in response to predetermined relationships related to speed differences between said input shaft and said pinion shaft.

16. The power transfer assembly of claim 15 wherein said logic further includes a sub-routine to compensate for changes in fluid viscosity within said fluid source based on the fluid temperature detected by said first temperature sensor.

17. The power transfer assembly of claim 10 wherein said controller is adapted to open said control valve and release engagement of said clutch pack when the fluid temperature detected by said second temperature sensor exceeds a predetermined value.

18. The power transfer assembly of claim 10 wherein said coupling is disposed within a housing which also rotatably supports said input shaft and pinion shaft, wherein said pump is adapted to generate a pumping action in response to speed differentiation between said pinion shaft and said input shaft, and wherein said control valve is mounted to a valvebody segment of said housing.

19. An all-wheel drive vehicle comprising:

20. The all-wheel drive vehicle of claim 19 wherein said traction control unit includes logic for controlling actuation of said control valve in response to predetermined relationships related to vehicle operating characteristics.

21. The all-wheel drive vehicle of claim 20 wherein said logic further includes a sub-routine to compensate for changes in fluid viscosity within said fluid source based on the fluid temperature detected by said first temperature sensor.

22. The all-wheel drive vehicle of claim 19 wherein said traction control unit is adapted to open said control valve and release engagement of said clutch pack when the fluid temperature detected by said second temperature sensor exceeds a predetermined value.

23. The all-wheel drive vehicle of claim 19 further comprising a second hydraulic coupling operably disposed between said drive case and at least one of said axleshafts for limiting excessive speed differentiation between the wheels.

24. An all-wheel drive vehicle comprising:

25. The all-wheel drive vehicle of claim 24 wherein said controller includes logic for controlling actuation of said control valve in response to predetermined relationships related to speed differences between said input shaft and said pinion shaft.

26. The all-wheel drive vehicle of claim 25 wherein said logic further includes a sub-routine for compensating for changes in fluid viscosity within said fluid source based on the fluid temperature detected by said first temperature sensor.

27. The all-wheel drive vehicle of claim 24 wherein said controller is adapted to open said control valve and release engagement of said clutch pack when the fluid temperature detected by said second temperature sensor exceeds a predetermined value.