AUTOMATIC BRAKING SYSTEM

• US 20080167161A1
• Filed: 01/05/2007
• Published: 07/10/2008
• Est. Priority Date: 01/05/2007
• Status: Active Grant

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: General Motors Corporation (General Motors Company)
• Inventors: MITCHELL, ANDREW L., Caldwell, Brett R.
• Granted Patent: US 7,670,259 B2
• Time in Patent Office: Days
• US Class Current: 477/94
• CPC Class Codes: B60W 10/11 Stepped gearings
• CPC Class Codes: B60W 10/184 with wheel brakes
• CPC Class Codes: B60W 10/196 acting within the driveline, e.g. retarders
• CPC Class Codes: B60W 2552/15 Road slope, i.e. the inclination of a road segment in the longitudinal direction
• CPC Class Codes: B60W 30/18109 Braking
• CPC Class Codes: B60W 30/18136 Engine braking

Abstract

A system for braking a vehicle includes a transmission having a plurality of gear sets for establishing a plurality of forward and reverse gear ratios and an actuator for changing the gear ratios. The system also includes a plurality of sensors for detecting a plurality of vehicle operating parameters and an auxiliary brake for reducing a speed of the vehicle. A controller having a processor configured to receive a plurality of output signals from the plurality of sensors has control logic for activating one of the actuator and the auxiliary brake based on the received output signals. A method for operating the system for braking is also provided. The method includes determining road grade, determining an acceleration of the vehicle, determining an activation status of the primary brake, determining a position of the throttle, determining whether extra braking is and activating the auxiliary brake based on the extra braking determination.

Claims

1. A system for braking a vehicle comprising:

a transmission having a plurality of gear sets for establishing a plurality of forward and reverse gear ratios and an actuator for changing the gear ratios;

a plurality of sensors for detecting a plurality of vehicle operating parameters;

an auxiliary brake for reducing a speed of the vehicle; and

a controller having a processor configured to receive a plurality of output signals from the plurality of sensors and wherein the controller has control logic for activating one of the actuator and the auxiliary brake based on the received output signals.

2. The system of claim 1 further comprising a primary brake for reducing the speed of the vehicle and wherein the control logic includes a first control logic for determining if the primary brake is activated.

3. The system of claim 2 further comprising a throttle for controlling an acceleration of the vehicle and wherein the control logic includes a second control logic for determining a position of the throttle.

4. The system of claim 3, wherein the control logic includes a third control logic for calculating a road grade from the operating parameters detected by the plurality of sensors.

5. The system of claim 4, wherein the plurality of operating parameters detected from the plurality of sensors includes an output signal indicative of an acceleration of the vehicle.

6. The system of claim 5, wherein the plurality of operating parameters detected from the plurality of sensors includes an output signal indicative of a speed of the vehicle.

7. The system of claim 6, wherein the control logic includes a fourth control logic to activate one of the auxiliary brake or actuator based on the primary brake activation, the throttle activation, the road grade, the acceleration, and the speed.

8. The system of claim 6, wherein the control logic includes a fifth control logic for recording an amount of time that the acceleration of the vehicle is less than a first threshold.

9. The system of claim 8, wherein the control logic includes a sixth control logic for recording a second amount of time that the acceleration is less than a second threshold and the auxiliary brake is activated.

10. The system of claim 9, wherein the control logic includes a seventh control logic for recording a third amount of time that the acceleration value is greater than a third threshold compensated by an acceleration magnitude.

11. The system of claim 10, wherein the control logic includes an eighth control logic for recording a fourth amount of time that the acceleration value is greater than a fourth threshold and the auxiliary brake is activated compensated by an acceleration magnitude.

12. The system of claim 11, wherein the control logic includes a ninth control logic for determining a fifth amount of time that the primary brake has been activated.

13. The system of claim 12, wherein the control logic includes a tenth control logic for combining the road grade, the throttle position, the speed, the first time, the second time, the third time, the fourth time, and the fifth time into a combined value, and the combined value is used to determine whether to activate one of the auxiliary brake and the actuator.

14. The system of claim 13, wherein the combined value determines whether the auxillary brake is activated, whether the actuator is activated, or whether both the auxiliary brake and the actuator are activated together.

15. A method for braking a vehicle having a throttle, a primary brake and an auxiliary brake, the method comprising the following steps:

determining a road grade;

determining an acceleration of the vehicle;

determining an activation status of the primary brake;

determining a position of the throttle;

determining whether extra braking is desirable based on the road grade, the acceleration of the vehicle, the activation status of the primary brake, and the position of the throttle; and

activating the auxiliary brake based on the extra braking determination.

16. The method of claim 15, wherein determining whether extra braking is desirable further comprises determining whether the road grade exceeds a road grade threshold, whether the vehicle is accelerating, whether the primary brake is activated, and the position of the throttle.

17. The method of claim 16 further comprising determining a first amount of time the vehicle acceleration is different than a first threshold, a second amount of time the vehicle acceleration is different than a second threshold with the auxiliary brake activated, and a third amount of time the primary brake is activated.

18. The method of claim 17 wherein determining whether extra braking is desirable includes combining the road grade, the speed of the vehicle, the position of the throttle, the first time, the second time, and the third time into a combined factor.

19. The method for braking of claim 18, wherein the combined factor is compared to an auxiliary brake threshold and the auxiliary brake is activated if the combined factor is greater than the auxiliary brake threshold.

20. The method for braking of claim 19, wherein the vehicle includes an automatic transmission with a plurality of drive ratios, and determining whether extra braking is desirable includes comparing the combined factor to a downshift threshold and the drive ratio is changed when the combined factor is greater than the downshift threshold.