Transmission Downshift Control Method

• US 20080081736A1
• Filed: 09/29/2006
• Published: 04/03/2008
• Est. Priority Date: 09/29/2006
• Status: Active Grant

• Current Assignee: FCA US LLC (Stellantis NV)
• Original Assignee: Chrysler Group LLC (Stellantis NV)
• Inventors: Chen, Gang
• Granted Patent: US 7,608,013 B2
• Time in Patent Office: Days
• US Class Current: 477/116
• CPC Class Codes: F16H 2061/0451 during swap-shifts, i.e. gear shifts between different planetary units, e.g. with double transitions shift involving three or more friction members
• CPC Class Codes: F16H 61/0437 by using electrical signals F16H61/0403 and F16H61/061 take precedence
• CPC Class Codes: F16H 61/702 using electric or electrohydraulic control means

Abstract

A method of controlling a downshift in a transmission having a main box and a compounder that has at least one gearset and at least one friction element separate from the main box includes initiating an upshift in the compounder including application of at least one friction element (e.g. a clutch) in the compounder, and releasing a friction element (e.g. a clutch) in the main box providing a swap shift. The speed phase in the compounder may trigger the speed phase in the main box, and vice versa. Target fluid volumes in one or both of a clutch being released in the main box and a clutch being applied in the compounder may be controlled and adjusted, if necessary, as a function of specific event timing in prior shifts.

Claims

1. A method of controlling a downshift in a transmission having a main box and a compounder coupled to the main box and having at least one gearset and at least one clutch separate from the main box, the method comprising:

initiating an upshift in the compounder including application of at least one clutch in the compounder;

initiating venting of a clutch being released in the main box;

determining occurrence of slip in the compounder and the main box;

controlling, after slip has occurred in the main box, the duty cycle of a solenoid associated with the clutch being released in the main box as a function of a desired acceleration of the main box;

determining a target input speed for the gear into which the transmission is being shifted;

initiating filling of a clutch to be applied in the main box; and

controlling the duty cycle of the solenoid of the clutch being applied in the main box when the input speed exceeds the target input speed to control the apply rate of the clutch being applied to bring the input speed to the target input speed.

2. The method of claim 1 wherein the upshift in the compounder is initiated by controlling the duty cycle of a solenoid associated with the clutch being applied in the compounder to provide a rapid increase in a fluid volume in the clutch being applied until a desired fill volume is reached.

3. The method of claim 2 wherein the fill volume is associated with a pressure in the clutch that is less than the pressure at which the clutch has its required torque capacity.

4. The method of claim 1 which also includes controlling, after slip has occurred in the compounder, the duty cycle of a solenoid associated with the clutch being applied in the compounder to control the acceleration of the compounder.

5. The method of claim 1 wherein venting of a clutch being released in the main box occurs at a first rate until a target volume is reached in the clutch and thereafter occurs at a second rate.

6. The method of claim 5 wherein the second rate is lower than the first rate and the second rate is continued until slip occurs in the main box.

8. The method of claim 1 wherein controlling, after slip has occurred in the main box, the duty cycle of a solenoid associated with the clutch being released in the main box is accomplished with feedback to control the acceleration of the main box.

9. The method of claim 1 wherein the fluid volume in the clutch being applied in the compounder is increased at a first rate until a fill volume is reached, and thereafter the fluid volume is adjusted at a second rate until a target volume is reached, and wherein the method also comprises adjusting the target volume if, in at least one prior double swap downshift, slip in the main box occurred at a time different than a predetermined time.

10. The method of claim 1 wherein the fluid volume in the clutch being released in the main box is decreased at a first rate until a target volume is reached, and thereafter the fluid volume is adjusted at a second rate, and wherein the method also comprises adjusting the target volume if, in at least one prior double swap downshift, slip in at least one of the main box or the compounder occurred at a time different than a predetermined time.

11. The method of claim 1 which also includes controlling venting of the clutch being released in the main box to a point above where the clutch being released would slip under current torque conditions in the main box, and wherein the fluid volume of the clutch being applied in the compounder is increased to initiate a speed phase in the compounder which increases input torque to the main box and thereby causes the clutch being released in the main box to slip.

12. The method of claim 1 which also includes controlling filling of the clutch being applied in the main box to a point below where the clutch being released would initiate a speed phase in the compounder under current torque conditions in the compounder, and wherein the fluid volume of the clutch being released in the main box is decreased to initiate a speed phase in the main box which decreases torque to the compounder so that the clutch being applied in the compounder has required torque capacity and a speed phase is thereby initiated in the compounder.

13. The method of claim 11 wherein the fluid volume in the clutch being applied in the compounder is increased at a first rate until a fill volume is reached, and thereafter the fluid volume is adjusted at a second rate until a target volume is reached, and wherein the method also comprises adjusting the target volume if, in at least one prior double swap downshift, slip in the main box occurred at a time different than a predetermined time.

14. The method of claim 12 wherein the fluid volume in the clutch being released in the main box is decreased at a first rate until a target volume is reached, and thereafter the fluid volume is adjusted at a second rate, and wherein the method also comprises adjusting the target volume if, in at least one prior double swap downshift, slip in at least one of the main box or the compounder occurred at a time different than a predetermined time.

15. A method of controlling a double swap downshift in a transmission having a main box and a compounder coupled to the main box, the method comprising:

initiating application of a clutch in the compounder for an upshift in the compounder;

initiating release of a clutch in the main box for a downshift in the main box;

determining a compounder target speed and a target input speed for the selected gear into which the transmission is being shifted;

controlling the solenoid duty cycle associated with the clutch being applied in the compounder after slip has occurred in the compounder to control the deceleration of the compounder until the compounder speed is within a threshold value of the compounder target speed and thereafter completing the upshift in the compounder;

controlling the solenoid duty cycle associated with the clutch being released in the main box after slip has occurred in the main box to control the acceleration of the main box until the input speed is within a threshold value of the target input speed and thereafter completing the downshift in the main box.

16. The method of claim 15 wherein the upshift is initiated by controlling the duty cycle of a solenoid associated with the clutch being applied in the compounder to increase the fluid volume in the clutch being applied, and wherein the fluid volume is increased at a first rate until a desired fill volume is reached, and thereafter is increased at a second rate until a target volume is reached.

17. The method of claim 16 which also comprises adjusting the target volume if, in at least one prior double swap downshift, slip in the main box occurred at a time different than a predetermined time.

18. The method of claim 15 wherein initiating release of a clutch in the main box for a downshift in the main box includes venting a clutch to be released in the main box at a first rate until a target volume is reached and venting the same clutch at a second rate after the target volume is reached.

19. The method of claim 18 which also comprises adjusting the target volume if, in at least one prior double swap downshift, slip in at least one of the main box or the compounder occurred at a time different than a predetermined time.