Line pressure control with input shaft torque measurement

• US 9,488,267 B2
• Filed: 09/14/2012
• Issued: 11/08/2016
• Est. Priority Date: 09/14/2012
• Status: Expired due to Fees

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Yanakiev, Diana, Pietron, Gregory Michael, Fujii, Yuji, Di Cairano, Stefano, Kucharski, Joseph F., Riedle, Bradley Dean
• Primary Examiner(s): Troost, Aaron L
• Application Number:
  US13/617,788
• Publication Number:
  US 20140081541A1
• Time in Patent Office: 1,516 Days
• Field of Search: 701/51, 701/67
• US Class Current: 1/1
• CPC Class Codes: F16D 2500/1026 Hydraulic
• CPC Class Codes: F16D 2500/1027 Details about the hydraulic valves
• CPC Class Codes: F16D 2500/3024 Pressure
• CPC Class Codes: F16D 2500/3027 Torque
• CPC Class Codes: F16D 2500/30406 Clutch slip
• CPC Class Codes: F16D 2500/70406 Pressure
• CPC Class Codes: F16D 48/06 Control by electric or electronic means, e.g. of fluid pressure
• CPC Class Codes: F16H 59/14 Inputs being a function of torque or torque demand
• CPC Class Codes: F16H 61/0021 Generation or control of line pressure
• CPC Class Codes: F16H 61/04 Smoothing ratio shift
• CPC Class Codes: F16H 61/68 specially adapted for stepped gearings

Abstract

A method of controlling a line pressure in a transmission is provided. Line pressure in a transmission is set to a pressure value including a first term that is proportional to an input torque value. The first term has a coefficient of proportionality that is increased in response to a signal indicating clutch slippage. The input torque value is a measured input torque value in a steady-state condition. The input torque value may be a maximum of the measured input torque value and a driver demand torque value in a transient condition.

Claims

1. A method of controlling a transmission comprising:

supplying a fluid at a pressure to engage a clutch;

periodically adjusting the pressure in proportion to an input torque value based on a coefficient of proportionality between pressure and torque; and

in response to a signal indicating slip of the clutch, increasing the coefficient of proportionality such that the pressure is increased for all positive input torque values.

2. The method of claim 1 wherein the pressure when input torque is zero is based on a constant coefficient which is not adjusted in response to the signal indicating slip of the clutch.

3. The method of claim 1 wherein the transmission provides a finite number of discrete speed ratios between an input shaft and an output shaft;

and the method further comprises selecting a different coefficient of proportionality for some of the speed ratios.

4. The method of claim 1 wherein the input torque value is a measured input torque value in a steady state condition.

5. The method of claim 4 wherein, in a transient condition, the input torque value is a maximum of the measured input torque value and a driver demand torque value.

6. The method of claim 5 further comprising:

in a steady state condition, recording a difference between the driver demand torque value and the measured input torque value; and

in a transient condition, adding the difference to the driver demand torque value.

7. The method of claim 1 further comprising decreasing the coefficient of proportionality when the clutch is not slipping.

8. The method of claim 7 wherein the coefficient of proportionality is decreased only when it is greater than a predetermined initial coefficient.

9. A transmission comprising:

an input shaft;

a clutch having a torque capacity varying in relation to a hydraulic pressure; and

a controller in communication with pressure regulating devices such that signals from the controller influence the hydraulic pressure, the controller configured to

periodically adjust the hydraulic pressure in proportion to an input torque value based on a coefficient of proportionality between pressure and torque,

detect clutch slip events, and

increase the coefficient of proportionality in response to the slip events.

10. The transmission of claim 9 wherein a finite number of discrete speed ratios are provided between an input shaft and an output shaft, and wherein the controller is further configured to select a different coefficient of proportionality for some of the speed ratios.

11. The transmission of claim 9 wherein the input torque value is a measured input torque value in a steady state condition.

12. The transmission of claim 11 wherein, in a transient condition, the input torque value is a maximum of the measured input torque value and a driver demand torque value.

13. The transmission of claim 12 wherein the controller is further configured to:

in a steady state condition, record a difference between the driver demand torque value and the measured input torque value, and

in a transient condition, add the difference to the driver demand torque value.

14. A transmission controller comprising:

input communication channels for sensing an input torque and speeds of at least two shafts;

output communication channels for setting the state of pressure regulating devices; and

control logic configured to

send signals to the pressure regulating devices to set a hydraulic pressure to a pressure value, wherein the pressure value includes a first term which is proportional to an input torque value, the term having a coefficient of proportionality,

detect clutch slip events, and

increase the coefficient of proportionality in response to the slip events.

15. The transmission controller of claim 14 wherein the pressure value includes a second term that is independent of the input torque value.

16. The transmission controller of claim 14 wherein the input torque value is a measured input torque value in a steady state condition.

17. The transmission controller of claim 14 further comprising decreasing the coefficient of proportionality when the clutch is not slipping.

18. The transmission controller of claim 14 wherein the coefficient of proportionality is decreased only when it is greater than a predetermined initial coefficient.