Method of controlling a transmission park system of a vehicle equipped with an electronic transmission range select system

Patent metadata

Field	Value
Publication number	US-9371909-B2
Application number	US-201414340651-A
Country	US
Kind code	B2
Filing date	Jul 25, 2014
Priority date	Jul 25, 2014
Publication date	Jun 21, 2016
Grant date	Jun 21, 2016

Abstract

A method of controlling a transmission of a vehicle equipped with an electronic transmission range select system includes receiving an electronic request to actuate a transmission park system. A speed of the vehicle is sensed with each of a plurality of different speed sensors to define a plurality of different sensed vehicle speeds. Each of the plurality of different speed sensors provides a sensed vehicle speed that is independent and separate from the sensed vehicle speed from all of the other speed sensors. All of the different sensed vehicle speeds from the plurality of speed sensors is compared to each other to determine the lowest sensed vehicle speed. When the lowest sensed vehicle speed is equal to or less than a maximum allowable actuation speed, an electronic signal is sent from the transmission control unit to the transmission park system to actuate the transmission park system.

First claim

The invention claimed is:

1. A method of controlling an electronically actuated transmission park system of a vehicle, the method comprising:
sensing a speed of the vehicle with each of a plurality of different speed sensors to define a plurality of different sensed vehicle speeds, wherein each of the plurality of different speed sensors provides a sensed vehicle speed that is independent and separate from the sensed vehicle speeds of all of the other speed sensors;
comparing all of the different sensed vehicle speeds from the plurality of speed sensors to each other to determine the lowest sensed vehicle speed; and
actuating the transmission park system when the lowest sensed vehicle speed is equal to or less than a maximum allowable actuation speed.

2. A method as set forth in claim 1 further comprising requesting actuation of the transmission park system.

3. A method as set forth in claim 1 further comprising not actuating the transmission park system when the lowest sensed vehicle speed is greater than the maximum allowable actuation speed.

4. A method as set forth in claim 1 wherein the plurality of sensors includes at least one of a wheel speed sensor, a transmission output shaft speed sensor, or an electric propulsion motor speed sensor.

5. A method as set forth in claim 1 wherein at least one of the plurality of different sensors includes a hall effect based sensor.

6. A method as set forth in claim 1 wherein actuating the transmission park system includes sending an electronic signal to the transmission park system.

7. A method as set forth in claim 1 wherein sensing the speed of the vehicle with each of the plurality of different speed sensors includes:
each sensor sensing data related to rotation of a rotating element;
each sensor transmitting their respective data related to rotation of their respective rotating element to a transmission control unit; and
calculating a speed of the vehicle from the data from each respective sensor, with the transmission control unit.

8. A method as set forth in claim 1 further comprising individually diagnosing each of the plurality of speed sensors to determine if any of the plurality of speed sensors is not operating properly.

9. A method as set forth in claim 8 further comprising excluding the sensed vehicle speed from any of the plurality of speed sensors diagnosed as not operating properly from the comparison all of the different sensed vehicle speeds used to determine the lowest sensed vehicle speed.

10. A method as set forth in claim 1 further including defining one of the plurality of speed sensors as a default speed sensor, and wherein comparing all of the different sensed vehicle speeds from the plurality of speed sensors to each other to determine the lowest sensed vehicle speed includes selecting the sensed vehicle speed derived from the default speed sensor as the lowest sensed vehicle speed when the sensed vehicle speed from the default speed sensor and at least one other of the plurality of speed sensors are substantially equal to each other and are the lowest sensed vehicle speeds.

11. A method as set forth in claim 10 wherein the default speed sensor is a transmission output shaft speed sensor.

12. A method as set forth in claim 1 further comprising providing a transmission control unit operable to control the actuation of the transmission park system.

13. A method as set forth in claim 12 wherein the transmission control unit is operable to:
receive an electronic signal requesting actuation of the transmission park system;
receive sensed data from each of the plurality of different speed sensors;
calculate a sensed speed of the vehicle from the data received from each of the different speed sensors to define a plurality of different sensed vehicle speeds;
compare the plurality of different sensed vehicle speeds to determine which of the different sensed vehicle speeds is the lowest sensed vehicle speed;
compare the lowest sensed vehicle speed to the maximum allowable actuation speed to determine if the lowest sensed vehicle speed is less than, equal to, or greater than the maximum allowable actuation speed; and
actuate the transmission park system by sending an electronic signal to the transmission park system.

14. A method of controlling a transmission of a vehicle, the method comprising:
receiving an electronic request, with a transmission control unit, to actuate a transmission park system of the transmission;
sensing a speed of the vehicle with each of a plurality of different speed sensors to define a plurality of different sensed vehicle speeds, wherein each of the plurality of different speed sensors provides a sensed vehicle speed that is independent and separate from the sensed vehicle speed from all of the other speed sensors;
comparing all of the different sensed vehicle speeds from the plurality of speed sensors to each other to determine the lowest sensed vehicle speed; and
sending an electronic signal from the transmission control unit to the transmission park system to actuate the transmission park system when the lowest sensed vehicle speed is equal to or less than a maximum allowable actuation speed.

15. A method as set forth in claim 14 further comprising not actuating the transmission park system when the lowest sensed vehicle speed is greater than the maximum allowable actuation speed.

16. A method as set forth in claim 14 wherein the plurality of sensors includes at least one of a wheel speed sensor, a transmission output shaft speed sensor, or an electric propulsion motor speed sensor.

17. A method as set forth in claim 14 wherein at least one of the plurality of different sensors includes a hall effect based sensor.

18. A method as set forth in claim 14 wherein sensing the speed of the vehicle with each of the plurality of different speed sensors includes:
each sensor sensing data related to rotation of a rotating element;
each sensor transmitting their respective data related to rotation of their respective rotating element to the transmission control unit; and
calculating the speed of the vehicle from the data from each respective sensor, with the transmission control unit.

19. A method as set forth in claim 14 further comprising individually diagnosing each of the plurality of speed sensors to determine if any of the plurality of speed sensors is not operating properly.

20. A method as set forth in claim 19 further comprising excluding the sensed vehicle speed from any of the plurality of speed sensors diagnosed as not operating properly from the comparison all of the different sensed vehicle speeds used to determine the lowest sensed vehicle speed.

Assignees

• Gm Global Tech Operations Inc

Inventors

• Macfarlane Brian A
• Wang Orson S

Classifications

• F16H2061/1284

  the failing part is a sensor · CPC title

• F16H59/44 Primary

  dependent on machine speed {, e.g. the vehicle speed} (F16H59/46 takes precedence) · CPC title

• F16H63/483 Primary

  Circuits for controlling engagement of parking locks or brakes · CPC title

• F16H61/12

  Detecting malfunction or potential malfunction, e.g. fail safe (in control of hydrostatic gearing F16H61/4192) {; Circumventing or fixing failures} · CPC title

• F16H63/48

  Signals to a parking brake {or parking lock; Control of parking locks or brakes being part of the transmission} · CPC title