Temperature Compensation Method for an Air Suspension After Engine Shut-Off

• US 20110093166A1
• Filed: 10/16/2009
• Published: 04/21/2011
• Est. Priority Date: 10/16/2009
• 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: Darab, Johnathan, Opiteck, Steven A., Cui, John X., Moshchuk, Nikolai K., Li, Yunjun
• Granted Patent: US 9,050,871 B2
• Time in Patent Office: Days
• US Class Current: 701/40
• CPC Class Codes: B60G 17/019 characterised by the type of sensor or the arrangement thereof B60G17/01941 takes precedence
• CPC Class Codes: B60G 17/052 Pneumatic spring characteristics B60G17/048 takes precedence ; valves per se F16K
• CPC Class Codes: B60G 2400/842 Temperature
• CPC Class Codes: B60G 2500/30 Height or ground clearance

Abstract

A method for temperature compensating an air spring of an air spring suspension of a motor vehicle after engine shut-off. A desired trim height is obtained. At engine shut-off, the ambient temperature is measured and the temperature of air in the air spring determined. After a wait time (for loading/unloading), a start trim height is measured. A predicted trim height is determined for when the air in the air spring is at the ambient temperature. Finally, the volume of the air in the air spring is selectively adjusted so that when the air in the air spring arrives at the ambient temperature, the trim height will be about the desired trim height.

Claims

1. A method for temperature compensating an air spring of an air spring suspension of a motor vehicle after engine shut-off, comprising the steps of:

obtaining a desired trim height;

measuring ambient temperature; and

selectively adjusting volume of the air in the air spring to thereby provide a target trim height such that when the temperature of the air spring is at the ambient temperature, the trim height will be substantially the desired trim height.

2. The method of claim 1, further comprising:

determining temperature of air in the air spring;

measuring a start trim height at a predetermined time after the engine shut-off; and

determining a predicted trim height for when the air in the air spring will be at the ambient temperature responsive to said steps of measuring and said step of determining temperature;

wherein said step of selectively adjusting is responsive to said step of determining a predicted trim height; and

wherein said step of selectively adjusting is performed if the predicted trim height at that respective wheel corner is different from the desired trim height by at least a predetermined minimum trim height difference.

3. A method for temperature compensating an air spring of an air spring suspension of a motor vehicle after engine shut-off, comprising the steps of:

obtaining a desired trim height;

measuring ambient temperature;

determining temperature of air in the air spring;

measuring a start trim height at a predetermined time after the engine shut-off;

determining a predicted trim height for when the air in the air spring will be at the ambient temperature responsive to said steps of measuring and said step of determining temperature; and

selectively adjusting volume of the air in the air spring responsive to said step of determining a predicted trim height to thereby provide a target trim height such that when the temperature of the air spring is at the ambient temperature, the trim height will be substantially the desired trim height.

4. The method of claim 3, wherein said step of selectively adjusting is performed if the predicted trim height is different from the desired trim height by at least a predetermined minimum trim height difference.

5. The method of claim 4, wherein the predetermined time is a wait time for allowing loading and unloading of the motor vehicle to presumably complete.

6. The method of claim 5, wherein said step of selectively adjusting comprises:

adding air to the air spring if said step of predicting predicts the predicted trim height will be below the desired trim height; and

removing air in the air spring if said step of predicting predicts the predicted trim height will be above the desired trim height.

7. The method of claim 6, wherein said steps of determining a predicted trim height and selectively adjusting volume of the air in the air spring responsive to said step of predicting to thereby provide a target trim height are performed utilizing a predetermined gas law applicable to the air in the air spring.

8. The method of claim 6, wherein said step of determining the temperature of the air in the air spring comprises an algorithmic estimation of the component temperature responsive to a stored memory of driving conditions prior to the engine shut-off.

9. The method of claim 8, wherein said steps of determining a predicted trim height and selectively adjusting volume of the air in the air spring responsive to said step of predicting to thereby provide a target trim height are performed utilizing a predetermined gas law applicable to the air in the air spring.

10. A method for temperature compensating each air spring at each wheel corner of an air spring suspension of a motor vehicle after engine shut-off, comprising the steps of:

obtaining a desired trim height;

measuring ambient temperature;

determining temperature of air in the air spring at each of the wheel corners, respectively;

measuring a start trim height at a predetermined time after the engine shut-off at each of the wheel corners, respectively;

determining a predicted trim height at each wheel corner for when the air in each respective air spring will be at the ambient temperature, respectively, responsive to said steps of measuring and said step of determining temperature; and

selectively adjusting volume of the air in each respective air spring responsive to said step of predicting to thereby provide a target trim height at each wheel corner, respectively, such that when the temperature of each respective air spring is at the ambient temperature, the trim height at that respective wheel corner will be substantially the desired trim height;

wherein said step of selectively adjusting is performed if the predicted trim height at that respective wheel corner is different from the desired trim height by at least a predetermined minimum trim height difference.

11. The method of claim 10, wherein the predetermined time is a wait time for allowing loading and unloading of the motor vehicle to presumably complete.

12. The method of claim 11, wherein said step of selectively adjusting comprises:

adding air to a respective air spring if said step of predicting predicts the predicted trim height at that respective wheel corner will be below the desired trim height; and

removing air in a respective air spring if said step of predicting predicts the predicted trim height at that respective wheel corner will be above the desired trim height.

13. The method of claim 12, wherein said steps of determining a predicted trim height and selectively adjusting volume of the air in the air spring responsive to said step of predicting to thereby provide a target trim height are performed utilizing a predetermined gas law applicable to the air in the air spring.

14. The method of claim 12, wherein said step of determining the temperature of the air in each respective air spring comprises an algorithmic estimation of the component temperature responsive to a stored memory of driving conditions at each respective wheel corner prior to the engine shut-off.

15. The method of claim 14, wherein said steps of determining a predicted trim height and selectively adjusting volume of the air in the air spring responsive to said step of predicting to thereby provide a target trim height are performed utilizing a predetermined gas law applicable to the air in the air spring.