Two-speed transfer case with adaptive torque transfer clutch

• US 7,694,598 B2
• Filed: 04/04/2007
• Issued: 04/13/2010
• Est. Priority Date: 04/26/2006
• Status: Active Grant

• Current Assignee: Magna Powertrain AG & Company KG (Magna International Incorporated)
• Original Assignee: Magna Powertrain AG & Company KG (Magna International Incorporated)
• Inventors: Lippitsch, Klaus, Kriebernegg, August
• Primary Examiner(s): Lewis; Tisha D
• Application Number:
  US11/696,429
• Publication Number:
  US 20070251345A1
• Time in Patent Office: 1,105 Days
• Field of Search: 743/35, 743/375, 192/48.2, 192/48.5, 192/48.6, 192/48.7
• US Class Current: 74/337.5
• CPC Class Codes: B60K 17/344 having a transfer gear
• CPC Class Codes: F16H 2061/2869 Cam or crank gearing
• CPC Class Codes: F16H 2061/326 Actuators for range selection, i.e. actuators for controlling the range selector or the manual range valve in the transmission
• CPC Class Codes: F16H 61/32 Electric motors actuators or related electrical control means therefor
• CPC Class Codes: F16H 63/304 the final output mechanisms comprising elements moved by electrical or magnetic force band brake actuating mechanisms F16H63/3003
• CPC Class Codes: Y10T 74/19251 Control mechanism
• CPC Class Codes: Y10T 74/19279 Cam operated

Abstract

A transfer case includes a two-speed range unit, a friction clutch, a power-operated actuation mechanism and a control system. The actuation mechanism includes an electric motor, a geartrain driven by the motor for controlling rotation of an actuator shaft, a range actuator assembly and a mode actuator assembly. The range actuator assembly functions to move a shift collar associated with the range unit in response to rotation of the actuator shaft. The mode actuator assembly includes a mode cam and a ballramp unit. The mode cam is rotatively driven by the actuator shaft for controlling the clutch engagement force exerted on the friction clutch by the ballramp unit.

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 geartrain having an input gear driving an output gear;

an electric motor driving said input gear;

an actuator shaft driven by said output 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, said mode actuator including a mode cam driven by said actuator shaft and a ball ramp unit having a first cam member, a second cam member disposed for rotation and axial movement relative to said first cam member, and rollers disposed in cam grooves formed between said first and second cam members, said first cam member having a first lever segment disposed on one side of said actuator shaft and said second cam member having a second lever segment disposed on an opposite side of said actuator shaft which includes a mode follower engaging a cam surface on said mode cam, said cam surface is configured to cause movement of said second cam member relative to said first cam member between a retracted position and an extended position in response to rotation of said mode cam with 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 1 wherein said geartrain includes a first gearset having said input gear driven by said motor and a first transfer gear driven by said input gear for rotation about a first axis, and wherein said geartrain includes a second gearset having a second transfer gear driven by said first transfer gear and which drives said output gear for rotation about a second axis.

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

a follower fixed for rotation with said actuator shaft;

a range cam supported on said actuator shaft and having a shift slot within which said follower is disposed, said shift slot configured to convert rotary movement of said actuator shaft into axial movement of said range cam;

a shift fork coupled to said range clutch; and

a biasing mechanism interconnecting said shift fork to said range cam for converting axial movement of said range cam into axial movement of said shift fork for moving said range clutch between its first and second range positions.

7. The transfer case of claim 6 wherein said shift slot in said range cam includes 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.

8. 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 geartrain having an input gear and an output gear, a motor driving said input gear, an actuator shaft driven by said output gear, 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 mode actuator including a mode cam driven by said actuator shaft and a ball ramp unit having a first cam member, a second cam member disposed for rotation and axial movement relative to said first cam member, and rollers disposed in cam grooves formed between said first and second cam members, said first cam member having a first lever segment disposed on one side of said actuator shaft and said second cam member having a second lever segment disposed on an opposite side of said actuator shaft which includes a mode follower engaging a cam surface on said mode cam, said cam surface is configured to cause movement of said second cam member relative to said first cam member between a retracted position and an extended position in response to rotation of said mode cam with said actuator shaft for moving said pressure plate between its first and second mode positions, and wherein said actuator shaft being rotatable through three distinct ranges of rotary travel for causing said range actuator and said mode actuator to coordinate movement of said dog clutch and said pressure plate.

9. The transfer case of claim 8 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.

10. The transfer case of claim 8 wherein said geartrain includes a first gearset having said input gear driven by said motor and a first transfer gear driven by said input gear for rotation about a first axis, and wherein said geartrain includes a second gearset having a second transfer gear driven by said first transfer gear and which drives said output gear for rotation about a second axis.

11. The transfer case of claim 8 wherein said range actuator comprises:

a follower fixed for rotation with said actuator shaft;

a range cam supported on said actuator shaft and having a shift slot within which said follower is disposed, said shift slot is configured to convert rotary movement of said actuator shaft into axial movement of said range cam;

a shift fork coupled to said dog clutch; and

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

12. The transfer case of claim 11 wherein said shift slot in said range cam includes 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 dog 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 dog 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 dog clutch in its second range position during rotation of said actuator shaft through a third range of rotary travel.

13. A transfer case, comprising:

first and second shafts;

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

an actuator shaft;

an electric motor operable for rotating said actuator shaft; and

a mode actuator driven by said actuator shaft for shifting said mode clutch between its first and second modes, said mode actuator including a mode cam driven by said actuator shaft and a cam mechanism disposed between said mode cam and an axially moveable clutch component of said mode clutch, said cam mechanism including a first cam member having a first lever segment disposed on one side of said actuator shaft and a second cam member having a second lever segment disposed on an opposite side of said actuator shaft and supporting a follower engaging a cam surface on said mode cam, said cam surface is configured to cause relative rotation between said first and second cam members in response to rotation of said actuator shaft for moving said clutch component between first and second mode positions for shifting said mode clutch between its first and second modes.

14. The transfer case of claim 13 further including a control system for controlling actuation of said electric motor so as to control the direction and magnitude of rotary movement of said actuator shaft.

15. The transfer case of claim 13 wherein said cam mechanism further includes a cam surface formed between said first and second cam members operable to cause axial movement of said second cam member relative to said first cam member between first and second cam positions which, in turn, causes axial movement of said clutch component between its first and second mode positions.

16. The transfer case of claim 13 wherein said cam surface is formed on an outer edge surface of said mode cam, wherein said follower extends outwardly from said second lever segment of said second cam member and rollingly engages said cam surface, and wherein said first lever segment of said first cam member engages a collar mounted on said actuator shaft adjacent to said mode cam.

17. The transfer case of claim 13 wherein said first cam member is inhibited from axial and rotary movement relative to said second cam member.