Method of determining a default transmission output speed

• US 7,107,134 B1
• Filed: 11/18/2005
• Issued: 09/12/2006
• Est. Priority Date: 11/18/2005
• Status: Expired due to Fees

• Current Assignee: Delphi Technologies, Inc. (BorgWarner Incorporated)
• Original Assignee: Delphi Technologies, Inc. (BorgWarner Incorporated)
• Inventors: Herman, Andrew D., Dues, David Allen, Simpson, Kenneth M., Breidenbach, Hallett D., Melby, Steve L.
• Primary Examiner(s): Camby, Richard M.
• Application Number:
  US11/283,216
• Time in Patent Office: 298 Days
• Field of Search: 701/51, 701/55, 701/56, 701/57, 701/58, 701/62, 701/63, 701/65, 701/67, 477/34, 477/77, 192/3.51, 192/3.54, 192/3.63
• US Class Current: 701/51
• CPC Class Codes: B60W 2050/022 Actuator failures
• CPC Class Codes: B60W 2050/0292 Fail-safe or redundant systems, e.g. limp-home or backup systems
• CPC Class Codes: B60W 2520/10 Longitudinal speed
• CPC Class Codes: B60W 50/029 Adapting to failures or work around with other constraints, e.g. circumvention by avoiding use of failed parts

Abstract

A default value of transmission output speed in a motor vehicle powertrain having an automatic-shift multi-gear ratio power transmission is continuously updated based on a measured value of the output speed and other reliable speed data including transmission input speed and vehicle speed. The default value is substituted for the measured output speed when a malfunction of the output speed sensor is detected, and transitions back to the measured output speed when the output speed sensor malfunction is no longer present.

Claims

1. A default method of operation for a motor vehicle powertrain (10) including a multi-gear ratio power transmission (14), transmission output speed measuring apparatus (32c), transmission input speed measuring apparatus (32b), and vehicle speed measuring apparatus (38a, 38b, 36), the method comprising the step of:

detecting a malfunction (86, 96, 98) of the transmission output speed measuring apparatus (32c);

in response to a detected malfunction of the transmission output speed measuring apparatus (32c), determining a default transmission output speed value based on an input speed signal (128) produced by the transmission input speed measuring apparatus (32b) during a non-shifting mode of operation of said power transmission (14), and based on a vehicle speed signal (130) produced by the vehicle speed measuring apparatus (38a, 38b, 36) during a shifting mode of operation of said power transmission (14); and

substituting (28) said default transmission output speed value for an output speed signal produced by said transmission output speed measuring apparatus (32c) so long as a malfunction of said transmission output speed measuring apparatus (32c) is detected.

2. The method of claim 1, where the step of detecting a malfunction of the transmission output speed measuring apparatus (32c) includes the steps of:

determining if said vehicle speed signal is reliable (56);

if said vehicle speed signal is reliable, calculating an output speed value based on said vehicle speed signal (60), and a difference between the calculated output speed value and said output speed signal (90); and

comparing the calculated difference to a calibrated difference (96).

3. The method of claim 1, where the step of detecting a malfunction of the transmission output speed measuring apparatus (32c) includes the steps of:

calculating a gradient of said output speed signal (94); and

comparing the calculated gradient to a calibrated gradient (96, 98).

4. The method of claim 1, including the steps of:

detecting a recovery (100) of the transmission output speed measuring apparatus (32c); and

substituting said output speed signal for said default transmission output speed value (28) when recovery of said transmission output speed measuring apparatus (32c) is detected.

5. The method of claim 4, where the step of detecting a recovery (100) of the transmission output speed measuring apparatus (32c) includes the steps of:

determining if said vehicle speed signal is reliable (56);

if said vehicle speed signal is reliable, calculating an output speed value based on said vehicle speed signal (60), and a difference between the calculated output speed value and said output speed signal (90); and

comparing the calculated difference to a calibrated difference (100).

6. The method of claim 5, including the step of:

comparing said output speed signal to a calibrated output speed signal (100).

7. The method of claim 1, including the steps of:

determining if said vehicle speed signal is reliable (56);

if a malfunction (86, 96, 98) of the transmission output speed measuring apparatus (32c) is detected, said vehicle speed signal is not reliable, and said transmission (14) is operating in said shifting mode (82, 116), determining said default transmission output speed value (130) based on a value of said input speed signal prior to said shifting mode of said transmission (14).

8. The method of claim 1, including the steps of:

determining if said vehicle speed signal is reliable (56);

if a malfunction (86, 96, 98) of the transmission output speed measuring apparatus (32c) is detected, said vehicle speed signal is not reliable, and said transmission is operating in said shifting mode (82, 116), maintaining said default transmission output speed value constant (13) during said shifting mode of said transmission (14).

9. The method of claim 1, including the steps of:

low pass filtering said default transmission output speed signal (132);

computing a difference between said default transmission output speed signal and said filtered default transmission output speed signal (134); and

if the computed difference exceeds a calibrated difference (136), substituting (28) said filtered default transmission output speed value (138) for the output speed signal produced by said transmission output speed measuring apparatus (32c) so long as a malfunction of said transmission output speed measuring apparatus (32c) is detected.

10. The method of claim 1, including the step of:

determining if said input speed signal is reliable (106);

determining if said vehicle speed signal is reliable (56); and

activating a limp-home mode (108) of said transmission (14) if said input speed signal is not reliable (106) and a malfunction of the transmission output speed measuring apparatus (32c) is detected (104).

11. The method of claim 1, including the step of:

determining if said input speed signal is reliable (106);

determining if said vehicle speed signal is reliable (56); and

activating a limp-home mode (108) of said transmission (14) if said input speed signal is not reliable (106) and said vehicle speed signal is not reliable (104).