Torque Limiting Clutches For Power Transfer Units

Abstract

A power transfer unit is provided with a torque limiting assembly that limits the torque transferred to driveline components when torque peaks occur. The power transfer unit can include, a first shaft, a second output shaft receiving drive torque, a second output shaft, and a torque transfer mechanism. The torque transfer mechanism includes a coupling member and a biasing member. The coupling member is located between a driving member and a driven member and provides selective engagement therebetween when in an engaged position. The driving member and/or the driven member includes a recess therein receiving a portion of the coupling member when in the engaged position. The biasing member urges the coupling member and the driving member and/or driven member into the engaged position.

Description

DRAWINGS

The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.

FIG. 1 is a schematic view of a four-wheel drive vehicle equipped with a power transfer unit having an actively-controlled torque transfer clutch and a control system according to the present invention;

FIG. 2 is a schematic diagram of the power transfer unit of FIG. 1, defining a full-time two-speed transfer case equipped with a torque limiting coupling according to the present invention;

FIG. 3 is a sectional view of a first embodiment of the torque limiting coupling shown in FIG. 2;

FIG. 4 is a sectional view of a second embodiment of the torque limiting coupling shown in FIG. 2;

FIG. 5 is a sectional view of a third embodiment of the torque limiting coupling shown in FIG. 2;

FIG. 6 is a sectional view taken generally along line 6-6 of FIG. 5;

FIG. 7 is a sectional view of a fourth embodiment of the torque limiting coupling shown in FIG. 2;

FIG. 8 is an end view of the torque limiting coupling of FIG. 7;

FIG. 9 is a sectional view of a fifth embodiment of the torque limiting coupling shown in FIG. 2; and

FIG. 10 is a schematic diagram of an alternate example of the full-time two-speed transfer case of FIG. 2.

Claims

1. A power transfer unit comprising: a first shaft receiving drive torque from a power source;a second shaft in a driven engagement with an output member; anda torque limiting mechanism including a driving member driven by said first shaft, a driven member driven by said second shaft, a coupling member and a biasing member, said coupling member disposed between said driving member and said driven member and providing engagement therebetween, at least one of said driving member and said driven member having a recess therein receiving a portion of said coupling member, said coupling member being removed from said recess when a torque level applied by said first shaft to said torque limiting mechanism exceeds a torque limit, said biasing member urging said coupling member and said at least one of said driving member and said driven member into engagement.

2. The power transfer unit of claim 1 wherein said driving member and said driven member have a common axis of rotation.

3. The power transfer unit of claim 2 wherein said biasing member is arranged to provide a biasing force in a direction generally radially outwardly from said axis of rotation.

4. The power transfer unit of claim 2 wherein said biasing member is arranged to provide a biasing force in a direction generally parallel to said axis of rotation.

5. The power transfer unit of claim 2 wherein said coupling member is radially displaceable relative to said axis of rotation.

6. The transfer case of claim 2, wherein said coupling member is axially displaceable relative to said axis of rotation.

7. The power transfer unit of claim 1 wherein said biasing member is a spring.

8. The power transfer unit of claim 1 wherein said coupling member includes a rounded engagement surface.

9. The power transfer unit of claim 1 wherein said coupling member includes at least one ball.

10. The power transfer unit of claim 1 wherein said torque limiting mechanism includes an adjustment member in communication with said biasing member and operable to selectively adjust a biasing force of said biasing member.

11. The power transfer unit of claim 10 wherein said biasing member includes a spring, said adjustment member operable to selectively adjust the installed length of said spring.

12. The power transfer unit of claim 1 wherein each of said driving member and said driven member includes a recess receiving a portion of said coupling member.

13. The power transfer unit of claim 1 wherein said coupling member is fixed for rotation with one of said driving member and said driven member.

14. The power transfer unit of claim 13 wherein the other of said driving member and said driven member includes said recess therein.

15. The power transfer unit of claim 1 wherein said at least one of said driving member and said driven member having a recess therein includes a plurality of recesses therein.

16. A transfer case comprising: an input shaft;a first output shaft in a driven engagement with said input shaft;a second output shaft in a driven engagement with said first output shaft; anda torque limiting mechanism drivingly disposed between said first output shaft and said second output shaft and including a coupling member and a biasing member, at least one of a driving member and a driven member having a recess therein configured to engage said coupling member, said at least one of said driving member and said driven member having said coupling member urged into an engagement therewith by said biasing member.

17. The transfer case of claim 16 wherein said coupling member is fixed for rotation with the other of said driving member and said driven member.

18. The transfer case of claim 16 wherein each of said driving member and said driven member includes a recess therein, said driving member and said driven member each rotatable relative to said coupling member.

19. The transfer case of claim 16 further comprising a two-speed range unit in a driven engagement with said input shaft.

20. The transfer case of claim 16 further comprising an interaxle differential in a driven engagement with said input shaft.

21. The transfer case of claim 16 further comprising a clutch assembly in a driven engagement with said input shaft.

22. A power transfer unit comprising: a first shaft;a second shaft; anda torque limiting mechanism drivingly disposed between said first shaft and said second output and including a coupling member and a biasing member, at least one of a driving member and a driven member having a recess therein configured to engage said coupling member, said biasing member urging said coupling member into an engaged position.

23. The power transfer unit of claim 22, wherein said coupling member is fixed for rotation with one of said driving member and said driven member, the other of said driving member and said driven member having said recess therein.