Torque modulation shift control system and method

• US 6,352,492 B1
• Filed: 04/06/2000
• Issued: 03/05/2002
• Est. Priority Date: 04/06/2000
• Status: Expired due to Term

• Current Assignee: Eaton Intelligent Power Limited (Eaton Corporation PLC.)
• Original Assignee: Eaton Corp. (Wisconsin) (Eaton Corporation PLC.)
• Inventors: Steeby, Jon A., Boardman, Mark A., Dedow, Warren R.
• Primary Examiner(s): Wright, Dirk
• Application Number:
  US09/543,927
• Time in Patent Office: 698 Days
• Field of Search: 477/109
• US Class Current: 477/109
• CPC Class Codes: B60W 10/06 including control of combustion engines
• CPC Class Codes: B60W 10/111 with separate change-speed gear trains arranged in series
• CPC Class Codes: B60W 30/19 Improvement of gear change, e.g. by synchronisation or smoothing gear shift
• CPC Class Codes: F16H 2306/32 Preparing the opening or release of the torque transmitting element
• CPC Class Codes: F16H 2306/44 Removing torque from current gears
• CPC Class Codes: F16H 2306/46 Uncoupling of current gear
• CPC Class Codes: F16H 61/0248 Control units where shifting is directly initiated by the driver, e.g. semi-automatic transmissions generation of movements for final actuating mechanisms F16H61/28
• CPC Class Codes: F16H 61/70 specially adapted for change-speed gearing in group arrangement, i.e. with separate change-speed gear trains arranged in series, e.g. range or overdrive-type gearing arrangements
• CPC Class Codes: F16H 63/502 for smoothing gear shifts

Abstract

A shift control system is provided that is suitable for semi-automatic transmissions in heavy duty vehicles. The torque modulation system includes logic circuitry that employs a ramping torque function or algorithm to control the acceleration of torque, both positive and negative, and/or provides a longer dwell time in the torque clutch disengagement range. Moreover, dwell time at peak is not required. A method for improving gear disengagement and shift control in accordance with the principles of the invention is also disclosed.

Claims

1. A shift control system for a vehicular drive train having a plurality of groups of gears with each of said groups having at least one gear manually selectable by an operator and including a plurality of sequentially related gears, said drive train including a torque-producing device, an actuator for enabling automatic shifting at the particular gear position desired and logic circuitry that employs a ramping function to control the acceleration of torque to provide improved gear disengagement, and wherein the ramping function is capable of controlling both positive and negative torque acceleration.

2. A system as recited in claim 1, wherein the ramping function controls the acceleration of both positive and negative torque.

3. A system as recited in claim 1, wherein the ramping function includes a plurality of individual ramps having a ramp rate up, an apex, and a ramp rate down.

4. A system as recited in claim 3, wherein at the apex of the individual ramp, either a requisite torque value for disengagement is acheived or the torque is ramped down.

5. A system as recited in claim 3, wherein the ramp rate up of an individual ramp is substantially the same as the ramp rate down for said individual ramp.

6. A system as recited in claim 1, wherein the magnitude of the torque for an individual ramp is within the range of about ±

5% of the magnitude of the total available engine torque at the start of the event of disengagement.

7. A system as recited in claim 1, wherein dwell time is included between sequentially successive individual ramps.

8. A system as recited in claim 1, wherein dwell time is included between alternating positive and negative sequentially successive individual ramps.

9. A system as recited in claim 1, wherein dwell time is calculated in the zero torque range.

10. A system as recited in claim 8, wherein the dwell time is approximately 100 ms.

11. A system as recited in claim 1, wherein the system does not include dwell time at the peak torque at the start of an event of gear disengagement.

12. A system as recited in claim 1, wherein the magnitude of the individual torque ramps may be increased as time progresses if disengagement is not achieved.

13. A system as recited in claim 1, including at least one sensor for sensing gear disengagement.

14. A shift control system for a vehicular drive train having a plurality of groups of gears with each of said groups having at least one gear manually selectable by an operator and including a plurality of sequentially related gears, said drive train including an actuator for enabling automatic shifting at the particular gear position desired and logic circuitry that employs a dwell time between sequentially successive functions of torque controlled by the logic circuitry to provide improved gear disengagement.

15. A system as recited in claim 14, wherein the dwell time is included between alternating positive and negative sequentially successive functions of torque that are controlled by the logic circuitry.

16. A method for controlling torque value in a vehicle transmission having multiple gears, including the steps of:

determining a zero torque value;

determining an initial current torque value that is indicative of the current transmission condition;

changing the current torque value by manipulating a signal that is used for adjusting an engine variable so that the current torque value approaches the zero torque value; and

utilizing logic circuitry to employ a function to ramp the current torque value up and down in the form of an individual ramp as a function of time having a determined amplitude and period by adjusting an engine variable until a known transmission condition exists.

17. A method as recited in claim 16, wherein a plurality of ramps control the acceleration of positive and negative torque.

18. A method as recited in claim 17, wherein a dwell time is included between sequentially successive individual ramps.

19. A method as recited in claim 17, wherein ramps controlling positive and negative torque are alternated.

20. A method as recited in claim 17, wherein the magnitude of ramped torque values is increased as time progresses if disengagement of a gear is not achieved.

21. A method as recited in claim 17, including the step of modifying the ramp function for different vehicle transmission environments.

22. A method as recited in claim 21, wherein an algorithm is used to modify the ramp function to optimize the configuration of an individual ramp.