Synchronous shift control in an electrically variable transmission

• US 20050080540A1
• Filed: 10/14/2003
• Published: 04/14/2005
• Est. Priority Date: 10/14/2003
• Status: Active Grant

• Current Assignee: Allison Transmission Incorporated (Allison Transmission Holdings Incorporated)
• Original Assignee: GM Global Technology Operations Incorporated (Motors Liquidation Co. GUC Trust)
• Inventors: Sah, Jy-Jen F., Hsieh, Tung-Ming, Steinmetz, Todd M.
• Granted Patent: US 7,356,398 B2
• Time in Patent Office: Days
• US Class Current: 701/55
• CPC Class Codes: B60K 6/445 Differential gearing distribution type
• CPC Class Codes: B60W 10/02 including control of driveline clutches
• CPC Class Codes: B60W 10/08 including control of electric propulsion units, e.g. motors or generators
• CPC Class Codes: B60W 10/11 Stepped gearings
• CPC Class Codes: B60W 20/00 Control systems specially adapted for hybrid vehicles hybrid vehicle design, B60K6/00; electric vehicles B60L
• CPC Class Codes: B60W 20/30 Control strategies involving selection of transmission gear ratio control of change speed gearings, together with other vehicle sub-units B60W10/10; HEV transmission gearing B60K6/36; gearings and control thereof F16H
• CPC Class Codes: B60W 2510/0241 Clutch slip, i.e. difference between input and output speeds
• CPC Class Codes: B60W 30/19 Improvement of gear change, e.g. by synchronisation or smoothing gear shift
• CPC Class Codes: F16H 2037/106 with switching means to provide two variator modes or ranges
• CPC Class Codes: F16H 2200/201 with three sets of orbital gears
• CPC Class Codes: F16H 2200/2035 with two engaging means
• CPC Class Codes: F16H 3/728 with means to change ratio in the mechanical gearing
• CPC Class Codes: Y02T 10/62 Hybrid vehicles

Abstract

Synchronous shift control in a multi-mode, hybrid transmission utilizes motor torques to control clutch synchronizations and torque conditions thereacross for substantially torque disturbance free shifting from one mode to another.

Claims

1. Method for controlling a shift from a first mode to a second mode in a multi-mode, electro-mechanical transmission including an input member and an output member, first and second torque transfer devices, at least one motor, first mode operation characterized by simultaneous first torque transfer device applied and second torque transfer device released, second mode operation characterized by simultaneous first torque transfer device released and second torque transfer device applied, and fixed-ratio operation characterized by simultaneous first and second torque transfer devices applied wherein the transmission input member is mechanically coupled to the transmission output member through a fixed ratio, comprising:

applying an oncoming torque transfer device while controlling slip speed across the oncoming torque transfer device to substantially zero by adjusting motor torque and thereafter releasing an offgoing torque transfer device while controlling slip speed across the offgoing torque transfer device to substantially zero by adjusting motor torque.

2. The method for controlling a shift as claimed in claim 1 wherein controlling slip speed across the oncoming torque transfer device to substantially zero by adjusting motor torque terminates when the oncoming torque transfer device is fully applied.

3. The method for controlling a shift as claimed in claim 1 wherein controlling slip speed across the offgoing torque transfer device to substantially zero by adjusting motor torque terminates when the offgoing torque transfer device is fully released.

4. The method for controlling a shift as claimed in claim 1 wherein controlling slip speed across the oncoming torque transfer device and the offgoing torque transfer device to substantially zero comprises controlling input member speed to a speed whereat the ratio of input member speed to output member speed is substantially said fixed ratio.

5. The method for controlling a shift as claimed in claim 1 wherein applying the oncoming torque transfer device is initiated when a predicted period needed for full torque transfer device engagement is substantially equivalent to a predicted period for oncoming torque transfer device slip speed to reach zero.

6. The method for controlling a shift as claimed in claim 5 wherein controlling slip speed across the oncoming torque transfer device to substantially zero by adjusting motor torque is initiated subsequent to initiation of applying the oncoming torque transfer device.

7. The method for controlling a shift as claimed in claim 6 wherein controlling slip speed across the oncoming torque transfer device to substantially zero by adjusting motor torque is initiated a predetermined time prior to slip speed across the oncoming torque transfer device reaching zero.

8. The method for controlling a shift as claimed in claim 7 wherein said predetermined time is a function of output member acceleration.

9. The method for controlling a shift as claimed in claim 5 wherein said predicted period needed for full torque transfer device engagement is adaptively learned.

10. The method for controlling a shift as claimed in claim 5 wherein said predicted period for oncoming torque transfer device slip speed to reach zero is determined from a trend in transmission speeds during said first mode operation.

11. The method for controlling a shift as claimed in claim 1 wherein said first mode of operation is preferred for low speed operation, said second mode of operation is preferred for high speed operation, and said shift is an upshift.

12. The method for controlling a shift as claimed in claim 1 wherein said first mode of operation is preferred for high speed operation, said second mode of operation is preferred for low speed operation, and said shift is a downshift.

13. Shift control for a multi-mode, electro-mechanical transmission including an input member and an output member, first and second torque transfer devices, at least one motor, first mode operation characterized by simultaneous first torque transfer device applied and second torque transfer device released, second mode operation characterized by simultaneous first torque transfer device released and second torque transfer device applied, and fixed-ratio operation characterized by simultaneous first and second torque transfer devices applied wherein the transmission input member is mechanically coupled to the transmission output member through a fixed ratio comprising:

a computer based controller for establishing motor torque in accordance with one of a plurality of motor controls including;

a mode motor control during which said transmission is operating in one of said first and second modes and motor torque is used to control transmission input member speed to a target determined independent of speed across the torque transfer devices,

a shift initiation motor control during which motor torque is used to control speed across an oncoming torque transfer device to substantially zero, and

a shift completion motor control during which motor torque is used to control speed across an offgoing torque transfer device to substantially zero.

14. The shift control as claimed in claim 13 further comprising a fixed-ratio motor control during which motor torque is not used in controlling transmission speeds.

15. The shift control as claimed in claim 13 wherein said shift initiation motor control is terminated when said oncoming torque transfer device is fully applied.

16. The shift control as claimed in claim 13 wherein said shift completion motor control is terminated when said offgoing torque transfer device is fully released.

17. The shift control as claimed in claim 13 wherein said shift initiation motor control and shift completion motor control comprise controlling input member speed to a speed whereat the ratio of input member speed to output member speed is substantially said fixed ratio.

18. Method for controlling a shift from a first mode to a second mode in a multi-mode, electro-mechanical transmission including an input member and an output member, first and second torque transfer devices, at least one motor, a first mode characterized by simultaneous first torque transfer device applied and second torque transfer device released, a second mode characterized by simultaneous first torque transfer device released and second torque transfer device applied, a fixed-ratio mode characterized by simultaneous first and second torque transfer devices applied wherein the transmission input member is mechanically coupled to the transmission output member through a fixed ratio comprising:

establishing synchronous operation of the transmission by using motor torque to control an oncoming torque transfer device slip to substantially zero;

establishing fixed-ratio operation of the transmission by transferring torque being carried by said at least one motor during synchronous operation of the transmission to the oncoming torque transfer device when the oncoming torque transfer device has established sufficient capacity to accept said transfer of torque without slipping; and

,

establishing synchronous operation of the transmission by transferring torque carried by an offgoing torque transfer device during fixed-ratio operation of the transmission to said at least one motor.

19. A shift control as claimed in claim 18 wherein prior to establishing synchronous operation of the transmission, using motor torque to control transmission input speed to a predetermined input speed target.

20. A shift control as claimed in claim 19 wherein subsequent to transferring torque carried by an offgoing torque transfer device to said at least one motor, using motor torque to control transmission input speed to a predetermined input speed target.