Method for Determining Trailer Braking Output

• US 20090204303A1
• Filed: 02/08/2008
• Published: 08/13/2009
• Est. Priority Date: 02/08/2008
• 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: Hartman, Katherin, Wu, Jiande, Schuelke, Thomas A., Leschuk, Robert W., Cui, John X.
• Granted Patent: US 8,165,768 B2
• Time in Patent Office: Days
• US Class Current: 701/71
• CPC Class Codes: B60T 13/662 characterised by specified functions of the control system components
• CPC Class Codes: B60T 7/12 for automatic initiation; for initiation not subject to will of driver or passenger limiting speed of vehicles other than rail vehicles B60K31/00
• CPC Class Codes: B60T 7/20 specially for trailers, e.g. in case of uncoupling of or overrunning by trailer inertia-actuated overrun brakes B60T13/08
• CPC Class Codes: B60T 8/1708 for lorries or tractor-trailer combinations

Abstract

A method for providing a trailer equipped with trailer brakes with an electronically controlled trailer braking output to help slow a vehicle/trailer combination as quickly as possible, but in a stable and balanced manner. In situations where a low friction environment is detected, such as a wet or icy road, the present method can brake the trailer in a more aggressive manner than a gain setting would normally allow. This gain-independent segment of the trailer braking output can result in a shorter stopping distance for the vehicle/trailer combination, without causing excessive trailer wheel lockup.

Claims

1. A method for determining trailer braking output for a trailer that is towed behind a vehicle, comprising the steps of:

(a) receiving vehicle braking input that is representative of vehicle braking conditions; and

(b) if the vehicle braking input indicates the presence of a low friction environment, then determining trailer braking output that has at least one gain-independent segment.

2. The method of claim 1, wherein the vehicle braking input of step (a) is representative of desired vehicle braking and is provided by at least one device selected from the group consisting of:

a brake switch, a pedal position sensor, a pressure sensor, or an antilock braking system (ABS).

3. The method of claim 2, wherein the vehicle braking input of step (a) further includes an ABS status signal that is provided by an antilock braking system (ABS) and is representative of the operational status of the ABS.

4. The method of claim 1, wherein the vehicle braking input of step (a) is representative of actual vehicle braking and is provided by at least one device selected from the group consisting of:

a vehicle speed sensor, a wheel speed sensor, or a vehicle accelerometer.

5. The method of claim 1, wherein the vehicle braking input of step (a) includes a first vehicle braking input representative of driver braking intent (DBI) and a second vehicle braking input representative of a low friction environment.

6. The method of claim 1, further comprising the step of:

receiving a gain setting; and

generating trailer braking output that includes a gain-dependent scaled segment where the trailer braking output is proportional to the vehicle braking input and a gain-dependent threshold segment where the trailer braking output is generally constant at a gain-dependent threshold.

7. The method of claim 6, further comprising the step of:

determining a gain-independent threshold that is generally independent of the gain setting.

8. The method of claim 7, wherein the gain-independent threshold is periodically adjusted.

9. The method of claim 7, wherein the gain-independent segment extends from a starting point to the lesser of the gain-dependent threshold and the gain-independent threshold.

10. The method of claim 1, wherein the gain-independent segment corresponds to a maximum available gain-dependent trailer braking output.

11. A method for determining trailer braking output for a trailer that is towed behind a vehicle, comprising the steps of:

(a) receiving a gain setting;

(b) receiving an ABS status signal from an antilock braking system (ABS) that is representative of the operational status of the ABS; and

(c) if the ABS status signal indicates that the ABS is currently active, then determining trailer braking output that has at least one segment where the trailer brakes are braked in a more aggressive manner than the gain setting would normally allow.

12. The method of claim 11, further comprising the step of:

receiving vehicle braking input in addition to the ABS status signal, wherein the additional vehicle braking input is representative of desired vehicle braking and is provided by at least one device selected from the group consisting of;

a brake switch, a pedal position sensor, or a pressure sensor.

13. The method of claim 11, further comprising the step of:

receiving vehicle braking input in addition to the ABS status signal, wherein the additional vehicle braking input is representative of actual vehicle braking and is provided by at least one device selected from the group consisting of;

a vehicle speed sensor, a wheel speed sensor, or a vehicle accelerometer.

14. The method of claim 11, further comprising the step of:

generating trailer braking output that includes a gain-dependent scaled segment where the trailer braking output is proportional to the vehicle braking input and a gain-dependent threshold segment where the trailer braking output is generally constant at a gain-dependent threshold.

15. The method of claim 14, further comprising the step of:

determining a gain-independent threshold that is generally independent of the gain setting received in step (a).

16. The method of claim 15, wherein the gain-independent threshold is periodically adjusted.

17. The method of claim 15, wherein the at least one segment is a gain-independent segment that extends from a starting point to the lesser of the gain-dependent threshold and the gain-independent threshold.

18. The method of claim 11, wherein the at least one segment corresponds to a maximum available gain-dependent trailer braking output.

19. A method for determining a trailer braking output for a trailer that is towed behind a vehicle, comprising the steps of:

(a) receiving vehicle braking input that includes a first vehicle braking input representative of the operational status of an antilock braking system (ABS) and a second vehicle braking input representative of driver braking intent (DBI);

(b) receiving a gain setting from a gain adjustment device; and

(c) if the first vehicle braking input indicates that the ABS is active, then utilizing the second vehicle braking input and the gain setting to provide trailer braking output that includes at least one gain-independent segment and at least one gain-dependent segment, wherein the gain-independent segment drives the trailer brakes in a more aggressive manner than the gain-dependent segment would normally allow.