BARREL CAM SHIFT MECHANISM

• US 20110100144A1
• Filed: 11/04/2009
• Published: 05/05/2011
• Est. Priority Date: 11/04/2009
• Status: Active Grant

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations Incorporated (Motors Liquidation Co. GUC Trust)
• Inventors: Bradley, Jesse B., Grewal, Ajit S., Neelakantan, Vijay A., Olson, Bret M.
• Granted Patent: US 8,402,859 B2
• Time in Patent Office: Days
• US Class Current: 74/473.36
• CPC Class Codes: F16H 3/006 power being selectively transmitted by either one of the parallel flow paths
• CPC Class Codes: F16H 61/32 Electric motors actuators or related electrical control means therefor
• CPC Class Codes: F16H 61/688 with two inputs, e.g. selection of one of two torque-flow paths by clutches
• CPC Class Codes: F16H 63/18 the final actuating mechanism comprising cams
• CPC Class Codes: Y10T 74/19279 Cam operated
• CPC Class Codes: Y10T 74/20177 Particular element [e.g., shift fork, template, etc.]

Abstract

A shift mechanism for a dual clutch transmission employs a rotating barrel cam having at least three tracks which are engaged by and translate at least three associated cam followers. The cam followers extend from shift fork bodies which slide on rails and include shift forks which bi-directionally translate at least three synchronizer clutches which engage at least five forward gears or speeds and reverse. A single electric motor and gear train drive the barrel cam.

Claims

1. A barrel cam shift mechanism for a transmission comprising, in combination,

at least one shift fork body disposed for bi-directional translation and having a cam follower, said cam follower having a spring biased member,

a barrel cam having at least one cam track for receiving said spring biased member of said cam follower, said cam track having at least one means for directing said cam follower along one portion of said cam track in response to rotation of said barrel cam in one direction and directing said cam follower along another portion of said cam track in response to rotation of said barrel cam in an opposite direction, and

drive means for bi-directionally rotating said barrel cam.

2. The barrel cam shift mechanism of claim 1 further including at least one synchronizer clutch connected to and translated by said shift fork body.

3. The barrel cam shift mechanism of claim 1 further including at least one countershaft and a plurality of gears disposed on said countershaft.

4. The barrel cam shift mechanism of claim 1 wherein said barrel cam is supported for rotation on a shaft and said shaft is coupled to said drive means.

5. The barrel cam shift mechanism of claim 1 wherein said barrel cam includes a second cam track and a third cam track.

6. The barrel cam shift mechanism of claim 1 wherein said drive means includes a bi-directional electric motor and a speed reducing gear train.

7. The barrel cam shift mechanism of claim 1 wherein said barrel cam is coupled to a shaft driven by said drive means and said drive means includes a sensor for detecting a rotational position of said shaft.

8. A cam track shift mechanism for a dual clutch transmission comprising, in combination,

at least one spaced apart pair of gears and a synchronizer clutch disposed between said pair of gears

at least one shift fork body disposed for bi-directional translation, said shift fork body having a fork engaging said synchronizer clutch and a cam follower,

a cylindrical cam body having at least one cam track for receiving said cam follower, said cam track having means for guiding said cam follower toward a first portion of said track in response to rotation of said cam body in one direction and guiding said cam follower toward a second portion of said track in response to rotation of said cam body in an opposite direction, and

a bi-directional electric motor having an output driving a speed reduction assembly having an output driving said cam body.

9. The cam track shift mechanism of claim 8 wherein said cam follower includes a spring biased member.

10. The cam track shift mechanism of claim 8 wherein said directing means includes a spring biased gate.

11. The cam track shift mechanism of claim 8 further including a countershaft for receiving said pair of gears.

12. The cam track shift mechanism of claim 8 wherein said cylindrical cam body includes a second cam track and a third cam track.

13. The cam track shift mechanism of claim 8 wherein said cam track defines a center neutral position and left and right positions for selecting said gears.

14. A barrel cam shift mechanism for a dual clutch transmission comprising, in combination,

at least one synchronizer clutch,

at least one shift fork body disposed for axial translation on a rail, said shift fork body having a fork engaging said synchronizer clutch and a cam follower,

a barrel cam having at least one cam track for receiving said cam follower, said cam track having direction sensitive means for directing said cam follower along a first portion of said track after encountering said direction sensitive means during rotation of said barrel cam in one direction and directing said cam follower along a second portion of said track after encountering said direction sensitive means during rotation of said barrel cam in an opposite direction, and

a bi-directional electric motor having an output driving a speed reduction assembly having an output driving said barrel cam.

15. The barrel cam shift mechanism of claim 14 wherein said cam track defines a center neutral position and left and right positions for selecting gears.

16. The barrel cam shift mechanism of claim 14 wherein said barrel cam includes a second cam track and a third cam track.

17. The barrel cam shift mechanism of claim 14 wherein said barrel cam includes a second cam track, a third cam track and a fourth cam track.

18. The barrel cam shift mechanism of claim 14 wherein said direction sensitive means includes a spring biased cam follower and at least one step in said cam track.

19. The barrel cam shift mechanism of claim 14 wherein said direction sensitive means includes a spring biased pawl.

20. The barrel cam shift mechanism of claim 14 further including a rotational position sensor operably coupled to said output of said speed reduction assembly.