Two-speed transfer case

• US 20060128515A1
• Filed: 12/12/2005
• Published: 06/15/2006
• Est. Priority Date: 11/24/2003
• Status: Active Grant

• Current Assignee: Magna Powertrain Incorporated (Magna International Incorporated)
• Original Assignee: Magna Powertrain Incorporated (Magna International Incorporated)
• Inventors: Ronk, Aaron, Mueller, Joseph G.
• Granted Patent: US 7,399,251 B2
• Time in Patent Office: Days
• US Class Current: 475/210
• CPC Class Codes: B60K 17/3467 combined with a change speed gearing, e.g. range gear
• CPC Class Codes: Y10T 74/19079 Parallel

Abstract

A transfer case includes a two-speed range unit, a mode clutch, an actuation mechanism and a control system. The actuation mechanism includes an electric motor, an actuator shaft driven by the motor, a range actuator assembly and a mode actuator assembly. The range actuator assembly includes range, a cam driven by the actuator shaft and a shift fork having a follower retained in a groove formed in the cam and a fork engaging a shift collar associated with the range unit. The mode actuator assembly has a range cam member with cam surfaces and a control gear with rollers engaging the cam surfaces. The control gear is rotatively driven by the actuator shaft. The cam member is axially moveable for controlling engagement of the mode clutch. An anti-rotation mechanism limits rotation of the cam member in response to continued rotation of the control gear.

Claims

1. A transfer case comprising:

an input shaft;

first and second output shafts;

a range unit driven at a reduced speed relative to said input shaft;

a range clutch operable in a first range position to establish a drive connection between said input shaft and said first output shaft and further operable in a second range position to establish a drive connection between said range unit and said first output shaft;

a mode clutch operable in a first mode position to disengage said second output shaft from driven engagement with said first output shaft and further operable in a second mode position to establish a drive connection between said first output shaft and said second output shaft;

a worm gearset having a worm driving a worm gear;

a motor driving said worm;

an actuator shaft driven by said worm gear;

a range actuator driven by said actuator shaft for moving said range clutch between its first and second range positions;

a mode actuator driven by said actuator shaft for moving said mode clutch between its first and second mode positions; and

a control system for actuating said motor to control the magnitude and direction of rotation of said actuator shaft so as to coordinate movement of said range clutch and said mode clutch.

2. The transfer case of claim 1 wherein said actuator shaft is rotatable through three distinct ranges of travel.

3. The transfer case of claim 2 wherein rotation of said actuator shaft through a first range of travel causes said range actuator to move said range clutch between its first and second range positions while said mode actuator maintains said mode clutch in its first mode position, and wherein rotation of said actuator shaft through a second range of travel causes said range actuator to maintain said range clutch in its first range position while said mode actuator moves said mode clutch between its first and second mode positions.

4. The transfer case of claim 3 wherein rotation of said actuator shaft through a third range of travel causes said range actuator to maintain said range clutch in its second range position while said mode actuator moves said mode clutch between its first and second mode positions.

5. The transfer case of claim 3 wherein said first range of rotary travel of said actuator shaft equals about 180°

and said second range of rotary travel of said actuator shaft equals about 90°

.

6. The transfer case of claim 1 wherein said worm includes worm threads formed on a shaft driven by said motor that are meshed with worm teeth on said worm gear, and wherein said worm gear is fixed to said actuator shaft for driving a drive gear that is operable to drive said mode actuator.

7. The transfer case of claim 1 wherein said range actuator comprises:

a range cam fixed for rotation with said actuator shaft;

a shift fork coupled to said range clutch; and

a mechanism interconnecting said shift fork to said range cam which is operable to convert rotary movement of said range cam into axial movement of said shift fork for moving said range clutch between its first and second range positions.

8. The transfer case of claim 7 wherein said mechanism includes a follower secured to said shift fork which extends into a groove formed in said range cam, said groove including a first dwell segment, a second dwell segment and a shift segment interconnecting said first and second dwell segments, said shift segment is configured to cause axial movement of said range clutch between its first and second range positions during rotation of said actuator shaft through a first range of rotary travel, said first dwell segment is configured to maintain said range clutch in its first range position during rotation of said actuator shaft through a second range of rotary travel, and said second dwell segment is configured to maintain said range clutch in its second range position during rotation of said actuator shaft through a third range of rotary travel.

9. The transfer case of claim 1 wherein said mode actuator comprises:

a control gear rotatably driven by a drive gear fixed to said actuator shaft;

a cam member having a first cam surface, a second cam surface and an anti-rotation lug; and

a roller disposed between said control gear and said cam member that is adapted to engage said first and second cam surfaces, wherein said mode clutch is moveable between its first and second mode positions in response to movement of said cam member between a retracted position and an extended position relative to said control gear.

10. The transfer case of claim 9 wherein rotation of said drive gear within a first range of rotary travel causes corresponding rotation of said control gear through a first range of rotary travel, and wherein rotation of said control gear through its first range of rotary travel causes concurrent rotary movement of said cam member while said cam member is maintained in its retracted position.

11. The transfer case of claim 10 wherein rotation of said drive gear within a second range of rotary travel causes corresponding rotation of said control gear through a second range of rotary travel, and wherein rotation of said control gear through its second range of rotary travel causes said anti-rotation lug on said cam member to engage a first anti-rotation stop such that said control gear rotates relative to said cam member, whereby such relative rotation causes said roller to ride on said first cam surface and forcibly move said cam member between its retracted and extended positions.

12. The transfer case of claim 11 wherein rotation of said drive gear within a third range of rotary travel causes corresponding rotation of said control gear through a third range of rotary travel, and wherein rotation of said control gear through its third range of rotary travel causes said anti-rotation lug on said cam member to engage a second anti-rotation stop such that said control gear rotates relative to said cam member, whereby such relative rotation causes said roller to ride on said second cam surface and axially move said cam member between its retracted and extended positions.

13. A transfer case comprising:

an input shaft;

first and second output shafts;

a range unit driven by said input shaft and having an output component driven at a reduced speed relative to said input shaft;

a dog clutch operable in a first range position to couple said input shaft to said first output shaft for establishing a high-range drive connection, said dog clutch is further operable in a second range position to couple said output component of said range unit to said first output shaft for establishing a low-range drive connection;

a mode clutch including a clutch pack operably disposed between said first and second output shafts and a pressure plate moveable between a first mode position whereat a minimum clutch engagement force is exerted on said clutch pack and a second mode position whereat a maximum clutch engagement force is exerted on said clutch pack; and

an actuation mechanism including a worm gearset driving an actuator shaft, a motor driving said worm gearset, a range actuator driven by said actuator shaft for moving said dog clutch between its first and second range positions, and a mode actuator driven by said actuator shaft for moving said pressure plate between its first and second mode positions, said actuator shaft being rotatable through three distinct ranges of rotary travel for causing said range and mode actuators to coordinate movement of said dog clutch and said pressure plate.

14. The transfer case of claim 13 wherein said actuator shaft is rotatable through a first range of travel for causing said range actuator to move said dog clutch between its first and second range positions while said mode actuator maintains said pressure plate in its first mode positions, wherein said actuator shaft is rotatable through a second range of travel for causing said range actuator to maintain said dog clutch in its first range position while said mode actuator moves said pressure plate between its first and second mode positions, and wherein said actuator shaft is rotatable through a third range of travel for causing said range actuator to maintain said dog clutch in its second range position while said mode actuator moves said pressure plate between its first and second mode positions.

15. The transfer case of claim 14 wherein said first range of rotary travel of said actuator shaft equals about 180°

and said second and third ranges of rotary travel of said actuator shaft each equal about 90°

.

16. The transfer case of claim 13 wherein said mode actuator assembly comprises:

a drive gear fixed for rotation with said actuator shaft;

a control gear driven by said drive gear;

a cam member having a first cam surface, a second cam surface and an anti-rotation lug;

a roller mounted to said control gear and adapted to engage either of said first and second cam surfaces; and

a thrust member for causing axial movement of said pressure plate between its first and second mode positions in response to axial movement of said cam member between a retracted position and an extended position relative to said control gear.

17. The transfer case of claim 16 wherein rotation of said drive gear with said actuator shaft within its first range of rotary travel causes corresponding rotation of said control gear through a first range of rotary travel, and wherein rotation of said control gear through its first range of rotary travel causes concurrent rotary movement of said cam member while said cam member is maintained in its retracted position.

18. The transfer case of claim 17 wherein rotation of said drive gear with said actuator shaft within its second range of rotary travel causes corresponding rotation of said control gear through a second range of rotary travel, and wherein rotation of said control gear through its second range of rotary travel causes said anti-rotation lug on said cam member to engage a first anti-rotation stop such that said control gear rotates relative to said cam member, whereby such relative rotation causes said roller to ride on said first cam surface and forcibly move said cam member between its retracted and extended positions so as to cause corresponding movement of said pressure plate.

19. The transfer case of claim 18 wherein rotation of said drive gear with said actuator shaft within its third range of rotary travel causes corresponding rotation of said control gear through a third range of rotary travel, and wherein rotation of said control gear through its third range of rotary travel causes said anti-rotation lug on said cam member to engage a second anti-rotation stop such that said control gear rotates relative to said cam member, whereby such relative rotation causes said roller to ride on said second cam surface and axially move said cam member between its retracted and extended positions so as to cause corresponding movement of said pressure plate.

20. A transfer case comprising:

an input shaft;

first and second output shafts;

a range unit driven at a reduced speed relative to said input shaft;

a range clutch operable in a first range position to establish a drive connection between said input shaft and said first output shaft and further operable in a second range position to establish a drive connection between said range unit and said first output shaft;

a mode clutch operable in a first mode position to release said second output shaft from driven engagement with said first output shaft and further operable in a second mode position to establish a drive connection between said first and second output shafts;

an actuator shaft disposed between said first and second output shafts;

a range cam fixed for rotation with said actuator shaft;

a drive gear fixed for rotation with said actuator shaft;

a worm gearset having a worm gear fixed for rotation with said actuator shaft;

a motor driving said worm gearset to control rotation of said actuator shaft;

a range actuator assembly operably disposed between said range cam and said range clutch for controlling movement of said range clutch between its first and second range positions in response to rotation of said range cam;

a mode actuator assembly having a control gear meshed with said drive gear and a cam unit operable for controlling movement of said mode clutch between its first and second mode positions in response to rotation of said control gear; and

a control system for controlling actuation of said motor to control the amount and direction of rotation of said actuator shaft to coordinate movement of said range clutch and said mode clutch.

21. The transfer case of claim 20 wherein rotation of said actuator shaft through a first range of travel causes said range actuator to move said range clutch between its first and second range positions while said mode actuator maintains said mode clutch in its first mode position, and wherein rotation of said actuator shaft through a second range of travel causes said range actuator to maintain said range clutch in its first range position while said mode actuator moves said mode clutch between its first and second mode positions.

22. The transfer case of claim 21 wherein rotation of said actuator shaft through a third range of travel causes said range actuator to maintain said range clutch in its second range position while said mode actuator moves said mode clutch between its first and second mode positions.

23. The transfer case of claim 22 wherein said first range of rotary travel of said actuator shaft equals about 180°

and said second range of rotary travel of said actuator shaft equals about 90°

.

24. The transfer case of claim 20 wherein said range actuator comprises:

a range cam fixed for rotation with said actuator shaft;

a shift fork coupled to said range clutch; and

a mechanism interconnecting said shift fork to said range cam which is operable to convert rotary movement of said range cam into axial movement of said shift fork for moving said range clutch between its first and second range positions.

25. The transfer case of claim 24 wherein said mechanism includes a follower secured to said shift fork which extends into a groove formed in said range cam, said groove including a first dwell segment, a second dwell segment and a shift segment interconnecting said first and second dwell segments, said shift segment is configured to cause axial movement of said range clutch between its first and second range positions during rotation of said actuator shaft through a first range of rotary travel, said first dwell segment is configured to maintain said range clutch in its first range position during rotation of said actuator shaft through a second range of rotary travel, and said second dwell segment is configured to maintain said range clutch in its second range position during rotation of said actuator shaft through a third range of rotary travel.

26. The transfer case of claim 20 wherein said mode actuator comprises:

a control gear rotatably driven by a drive gear fixed to said actuator shaft;

a cam member having a first cam surface, a second cam surface and an anti-rotation lug; and

a roller disposed between said control gear and said cam member that is adapted to engage said first and second cam surfaces, wherein said mode clutch is moveable between its first and second mode positions in response to movement of said cam member between a retracted position and an extended position relative to said control gear.

27. The transfer case of claim 26 wherein rotation of said drive gear within a first range of rotary travel causes corresponding rotation of said control gear through a first range of rotary travel, and wherein rotation of said control gear through its first range of rotary travel causes concurrent rotary movement of said cam member while said cam member is maintained in its retracted position.

28. The transfer case of claim 27 wherein rotation of said drive gear within a second range of rotary travel causes corresponding rotation of said control gear through a second range of rotary travel, and wherein rotation of said control gear through its second range of rotary travel causes said anti-rotation lug on said cam member to engage a first anti-rotation stop such that said control gear rotates relative to said cam member, whereby such relative rotation causes said roller to ride on said first cam surface and forcibly move said cam member between its retracted and extended positions.

29. The transfer case of claim 28 wherein rotation of said drive gear within a third range of rotary travel causes corresponding rotation of said control gear through a third range of rotary travel, and wherein rotation of said control gear through its third range of rotary travel causes said anti-rotation lug on said cam member to engage a second anti-rotation stop such that said control gear rotates relative to said cam member, whereby such relative rotation causes said roller to ride on said second cam surface and axially move said cam member between its retracted and extended positions.