Process and system for detecting decrease in tire air-pressure and tire deflation judging program

• US 7,305,318 B2
• Filed: 07/06/2006
• Issued: 12/04/2007
• Est. Priority Date: 07/08/2005
• Status: Expired due to Fees

• Current Assignee: Sumitomo Rubber Industries Limited
• Original Assignee: Sumitomo Rubber Industries Limited
• Inventors: Kitano, Masashi
• Primary Examiner(s): Wachsman; Hal
• Assistant Examiner(s): Desta; Elias
• Application Number:
  US11/481,106
• Publication Number:
  US 20070010964A1
• Time in Patent Office: 516 Days
• Field of Search: 702/138, 702/142, 702/145, 702/146, 702/163, 702/185, 702/189, 731/468, 731/463, 731/464, 731/465, 731/466, 340/442, 340/447, 340/444, 701/31, 701/36, 701/99
• US Class Current: 702/148
• CPC Class Codes: B60C 23/061 by monitoring wheel speed measuring distance traversed on the ground by vehicles G01C22/00

Abstract

A judgment whether a decrease in tire air-pressure occurs or not is performed by a process comprising the steps of: detecting information on wheel rotational velocities of tires; obtaining a judgment value for decrease in tire air-pressure based on relative comparison between the detected information on wheel rotational velocities; storing the judgment value(s) into an average preparation buffer BF; obtaining an average value of the judgment value(s) stored in the average preparation buffer BF when the vehicle stops; writing the average value and the number of the judgment values into a nonvolatile memory 2e; expanding the average value written in the nonvolatile memory 2e into the average preparation buffer BF in duplicate corresponding to the number of the judgment values after the start of a drive of the vehicle; and calculating an average value of a prescribed number of judgment values stored in the average preparation buffer BF so as to compare the average value with a threshold value.

Claims

1. A process of detecting decrease in tire air-pressure based on wheel rotational velocities obtained from tires mounted on a vehicle, which comprises the steps of:

detecting wheel rotational velocities of the respective tires;

repeatedly performing a relative comparison between the detected wheel rotational velocities to thereby obtain judgment values for decrease in tire air-pressure;

storing the judgment values in an average preparation buffer;

calculating an average value of the judgment values stored in the average preparation buffer;

writing the average value and the number of the judgment values into a nonvolatile memory at a predetermined timing;

expanding the average value that is written in the nonvolatile memory into the average preparation buffer in duplicate corresponding to the number of judgment values;

calculating a subsequent average value of a prescribed number of judgment values that are stored in the average preparation buffer;

comparing the subsequent average value with a predetermined threshold value, to thereby obtain a judgment of whether or not a decrease in tire air-pressure has occurred; and

providing notification of the judgment of whether or not a decrease in tire air-pressure has occurred.

2. The process of detecting decrease in tire air-pressure according to claim 1, wherein the predetermined timing is when a drive of the vehicle is completed.

3. The method of detecting decrease in tire air-pressure according to claim 2, wherein the average value written in the nonvolatile memory is expanded into the average preparation buffer after a start of a subsequent drive of the vehicle.

4. A system for detecting decrease in tire air-pressure based on wheel rotational velocities obtained from tires mounted on a vehicle, which comprises:

rotational velocity sensors for detecting wheel rotational velocities of The respective tires;

judgment value calculating means for repeatedly performing a relative comparison between the detected wheel rotational velocities to thereby obtain judgment values for decrease in tire air-pressure;

an average preparation buffer for storing the judgment values;

a nonvolatile memory into which an average value of the judgment values and the number of samples are written;

writing means for writing the average value of the judgment values stored in the average preparation buffer and the number thereof into the nonvolatile memory at a predetermined timing;

expanding means for expanding the average value written in the nonvolatile memory into the average preparation buffer in duplicate corresponding to the number of the judgment values;

judging means for obtaining the average value of a prescribed number of judgment values stored in the average preparation buffer so as to compare the average value with a predetermined threshold value, to thereby obtain a judgment of whether or not a decrease in tire air-pressure has occurred; and

means for providing notification of the judgment of whether or not a decrease in tire air-pressure has occurred.

5. The system for detecting decrease in tire air-pressure according to claim 4, wherein the predetermined timing is when a drive of the vehicle is completed.

6. The system for detecting decrease in tire air-pressure according to claim 5, wherein the average value written into the nonvolatile memory is expanded into the average preparation buffer after a start of a subsequent drive of the vehicle.

7. A tire deflation judging program provided in computer-readable memory of a system for detecting decrease in tire air-pressure based on wheel rotational velocities obtained from tires mounted on a vehicle, the program, when executed, carrying out a method comprising the steps of:

detecting wheel rotational velocities of the respective tires;

repeatedly performing a relative comparison between the detected wheel rotational velocities to thereby obtain judgment values for decrease in tire air-pressure;

storing the judgment values in an average preparation buffer;

calculating an average value of the judgment values stored in the average preparation buffer;

writing the average value and the number of the judgment values into a nonvolatile memory at a predetermined timing;

expanding the average value that is written in the nonvolatile memory into the average preparation buffer in duplicate corresponding to the number of judgment values;

calculating a subsequent average value of a prescribed number of judgment values that are stored in the average preparation buffer;

comparing the subsequent average value with a predetermined threshold value, to thereby obtain a judgment of whether or not a decrease in tire air-pressure has occurred; and

providing notification of the judgment of whether or not a decrease in tire air-pressure has occurred.