Method and apparatus for determining tire condition using ideal gas law

• US 8,818,619 B2
• Filed: 08/02/2012
• Issued: 08/26/2014
• Est. Priority Date: 08/02/2012
• Status: Expired due to Fees

• Current Assignee: TRW Automotive USLLC (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Original Assignee: TRW Automotive USLLC (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Inventors: Juzswik, David L.
• Primary Examiner(s): Black, Thomas G.
• Assistant Examiner(s): WALLACE, DONALD JOSEPH
• Application Number:
  US13/565,372
• Publication Number:
  US 20140039752A1
• Time in Patent Office: 754 Days
• Field of Search: 701/32.9, 701/33.1, 701/34.4
• US Class Current: 701/34.4
• CPC Class Codes: B60C 23/02 Signalling devices actuated by tyre pressure hand-held tyre pressure gauges G01L17/00
• CPC Class Codes: B60C 23/0471 System initialisation, e.g. upload or calibration of operating parameters
• CPC Class Codes: B60C 23/0476 Temperature compensation of measured pressure values
• CPC Class Codes: B60C 23/0484 Detecting an ongoing tyre inflation

Abstract

An apparatus is provided for determining a tire operating condition including a tire-based pressure and temperature sensor and transmitter and a vehicle ignition system. A vehicle-based receiver/controller receives sensor signals and state of the ignition system. The controller provides an error signal when the sensed tire pressure is less than a set threshold value P_set and resets the error signal when the sensed tire pressure is greater than a reset threshold value P_rst. The receiver/controller determines the set threshold value P_set and the reset threshold value P_rst as a function of a calculated warm tire pressure value P_warm, determines a mole value N of the tire pressure, and adjusts the determined set threshold value P_set and the reset threshold value P_rst in response to the vehicle ignition state and a change in the determined mole value N. A display is provided for displaying the error signal.

Claims

1. An apparatus for determining a tire operating condition comprising:

a tire-based sensor for sensing tire pressure and temperature and transmitting a signal indicative thereof;

a vehicle ignition system;

a vehicle-based receiver/controller for receiving the signal from the tire-based sensor and for detecting the state of the vehicle ignition system, said controller providing an error signal when the sensed tire pressure is less than a set threshold value P_set and resetting the error signal when the sensed tire pressure is greater than a reset threshold value P_rst, the vehicle-based receiver/controller determining the set threshold value P_set and the reset threshold value P_rst as a function of a calculated warm tire pressure value P_warm, determining a mole value N of the tire pressure and adjusting the determined set threshold value P_set and the reset threshold value P_rst in response to the vehicle ignition state and a change in the determined mole value N; and

a display the displaying the error signal from the vehicle-based receiver/controller.

2. The apparatus of claim 1 wherein said mole count N is equal to the sensed tire pressure divided by the sensed tire temperature.

3. The apparatus of claim 1 wherein said vehicle-based receiver/controller calculates the warm tire pressure value P_warm equal to a recommended tire pressure value P_rec times a measured tire temperature value T_meas divided by a learned value of cold tire pressure temperature T_cold.

4. The apparatus of claim 3 wherein learned value the cold tire pressure temperature T_cold is adjusted in response to a change in the determined mole value N.

5. The apparatus of claim 3 wherein the set threshold P_set=P_warm plus a pressure tolerance value P_tol.

6. The apparatus of claim 3 wherein the reset threshold P_rst=P_warm minus a pressure tolerance value P_tol.

7. A method for determining a tire operating condition comprising the steps of:

sensing tire pressure;

sensing tire temperature;

providing a signal indicative of the sensed tire pressure and tire temperature;

sensing a state of the a vehicle ignition system;

providing an error signal when the sensed tire pressure is less than a set threshold value P_set;

resetting the error signal when the sensed tire pressure is greater than a reset threshold value P_rst;

calculating warm tire pressure value P_warm

determining the set threshold value P_set and the reset threshold value P_rst as a function of the calculated warm tire pressure value P_warm;

determining a mole value N of the tire pressure;

adjusting the determined set threshold value P_set and the reset threshold value P_rst in response to the vehicle ignition state and a change in the determined mole value N; and

displaying the provided error signal for the vehicle operator.

8. The method of claim 7 wherein said step of determining a mole value N is determined by dividing the sensed tire pressure by the sensed tire temperature.

9. The method of claim 7 wherein said step of calculating the warm tire pressure value P_warm includes multiplying a recommended tire pressure value P_rec times a measured tire temperature value T_meas divided by a learned value of cold tire pressure temperature T_cold.

10. The method of claim 9 wherein learned value the cold tire pressure temperature T_cold is adjusted in response to a change in the determined mole value N.

11. The method of claim 9 wherein the set threshold P_set is set equal to P_warm plus a pressure tolerance value P_tol.

12. The method of claim 9 wherein the reset threshold P_rst is set equal to P_warm minus a pressure tolerance value P_tol.