VEHICLE TRANSMISSION SHIFT INHIBIT METHOD AND APPARATUS

• US 20080221763A1
• Filed: 03/09/2007
• Published: 09/11/2008
• Est. Priority Date: 03/09/2007
• Status: Active Grant

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations Incorporated (Motors Liquidation Co. GUC Trust)
• Inventors: Cawthorne, William R., Wozniak, Leonard G.
• Granted Patent: US 7,957,873 B2
• Time in Patent Office: Days
• US Class Current: 701/62
• CPC Class Codes: F16H 2061/165 Preventing reverse gear shifts if vehicle speed is too high for safe shifting
• CPC Class Codes: F16H 61/18 Preventing unintentional or unsafe shift , e.g. preventing manual shift from highest gear to reverse gear

Abstract

A control method is provided including detecting transmission output speed and a forward and reverse shift request, and executing inhibit limits when the detected speed exceeds a predetermined threshold speed. The inhibit limits slow the output speed to zero upon detection of a shift request at output speeds above the threshold, with a pedal progression map executed upon reaching zero output speed. The limits approach zero output torque as vehicle speed increases, reaching zero at a relatively high speed and simulating a neutral transmission upon a detected shift request at high speed. A vehicle is also provided having a transmission, a sensor for detecting transmission output speed, a sensor for detecting a shift request, and a PCM having an algorithm and a threshold transmission output speed. The algorithm inhibits a shift event in the direction opposite that of vehicle travel upon detection when vehicle speed is greater than the threshold.

Claims

1. A method for controlling a transmission of a vehicle, the method comprising:

recording a threshold transmission output speed;

detecting the actual output speed of the transmission;

detecting a shift request in the direction opposite that of the direction of travel of the vehicle;

comparing said detected output speed to said threshold transmission output speed; and

executing a normal pedal progression map when said detected output speed is less than or equal to said threshold transmission output speed, and executing a set shift inhibit limits when said detected output speed is greater than said threshold transmission output speed, said shift inhibit limits being configured to inhibit a shift of the transmission in response to said shift request by slowing the vehicle below said threshold transmission output speed before executing said detected shift request.

2. The method of claim 1, wherein said transmission is a hybrid transmission.

3. The method of claim 1, including configuring the vehicle with at least one speed sensor, at least one shift sensor, and a powertrain control module (PCM), wherein said detecting the actual output speed of the transmission includes sensing said actual output speed using said at least one speed sensor and relaying said detected actual output speed to said PCM, and wherein said detecting a shift request includes sensing said shift request using said at least one shift sensor and relaying said detected shift request to said PCM.

4. The method of claim 1, wherein said detected actual output speed is greater than said threshold transmission output speed, said executing of said shift inhibit limits comprising gradually slowing said actual transmission output speed to zero upon said detection of said shift request, and executing said pedal progression map upon reaching said zero output speed, thereby enabling a smooth shifting event in response to said detected shift request.

5. The method of claim 4, wherein said inhibit limits gradually approach zero output torque as vehicle speed increases, reaching said zero output torque at a relatively high rate of vehicle speed, thereby simulating a neutral condition of the transmission upon said detected shift request at said relatively high rate of vehicle speed.

6. A method for inhibiting a shift in one direction in a transmission of a vehicle moving in the opposite direction, the method comprising:

recording a threshold transmission output speed in said controller;

detecting the actual output speed of the transmission;

detecting a shift request in said one direction;

configuring a controller with a forward pedal progression map having a set of forward shift inhibit limits, and with a reverse pedal progression map having a set of reverse shift inhibit limits, said controller being configured to execute a shift in said one direction in response to said shift request;

comparing said detected actual output speed to said threshold output speed; and

executing said reverse inhibit limits when the opposite direction is the forward direction, said detected actual output speed is greater than said threshold transmission output speed, and said one direction is the reverse direction; and

executing said forward inhibit limits when the opposite direction is the reverse direction, said detected actual output speed is greater than said threshold transmission output speed, and the one direction is the forward direction;

wherein said forward and said reverse inhibit limits are configured to slow the vehicle below said threshold transmission output speed before said executing of said shift request.

7. The method of claim 6, wherein said transmission is a hybrid transmission.

8. The method of claim 6, wherein said executing said forward and said reverse inhibit limits are configured to gradually slow the vehicle until said detected actual output speed reaches zero.

9. The method of claim 6, including configuring the vehicle with at least one speed sensor and at least one shift sensor, wherein said detecting said actual transmission output speed includes sensing said actual transmission output speed using said at least one speed sensor and relaying said detected actual transmission output speed to said controller, and wherein said detecting a shift request includes sensing said shift request using said at least one shift sensor and relaying said detected shift request to said controller.

10. A vehicle comprising:

a transmission having a detectable actual output speed;

a speed sensor operable for detecting said actual output speed;

a shift sensor operable for detecting a shift request in the direction opposite the direction of vehicle travel; and

a programmable control module (PCM) having a stored threshold output speed value and an algorithm enabling a smooth shift event upon detection of said shift request when said detected actual output speed is greater than said threshold transmission output speed.

12. The vehicle of claim 11, including a forward and a reverse set of shift inhibit limits, wherein said PCM is operable for selecting said forward set of inhibit limits when said detected actual output speed is greater than said threshold transmission output speed and said direction of vehicle travel is the reverse direction, and for selecting said reverse set of shift inhibit limits when said detected actual output speed is greater than said threshold transmission output speed and said direction of vehicle travel is the forward direction.

13. The vehicle of claim 12, wherein each of said sets of inhibit limits approach zero output torque as the vehicle speed increases, reaching said zero output torque at a relatively high rate of vehicle speed, thereby simulating a neutral condition of said transmission upon said detected shift request at said relatively high rate of vehicle speed.

14. The vehicle of claim 11, wherein said transmission is a hybrid transmission.