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

• US 20070010964A1
• Filed: 07/06/2006
• Published: 01/11/2007
• Est. Priority Date: 07/08/2005
• Status: Active Grant

• Current Assignee: Sumitomo Rubber Industries Limited
• Original Assignee: Sumitomo Rubber Industries Limited
• Inventors: Kitano, Masashi
• Granted Patent: US 7,305,318 B2
• Time in Patent Office: Days
• 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;

obtaining a judgment value for decrease in tire air-pressure based on a relative comparison between the obtained wheel rotational velocities;

storing the judgment value in an average preparation buffer;

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

calculating an average value of a prescribed number of judgment values that are stored in the average preparation buffer so as to compare the average value with a predetermined threshold value, thereby judging whether or not a decrease in tire air-pressure occurs.

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 timing at which the average value written in the nonvolatile memory is expanded into the average preparation buffer in duplicate corresponding to the number of judgment values is after a start of the 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 obtaining a judgment value for decrease in tire air-pressure based on a relative comparison between the detected wheel rotational velocities;

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; and

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, thereby judging whether or not a decrease in tire air-pressure occurs.

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 timing at which the average value written into the nonvolatile memory is expanded into the average preparation buffer in duplicate corresponding to the number of the judgment values is after a start of the subsequent drive of the vehicle.

7. A tire deflation judging program, which is executed by a computer for detecting a decrease in tire air-pressure based on wheel rotational velocities obtained from rotational velocity sensors of tires mounted on a vehicle, comprising:

judgment value calculating means for obtaining a judgment values for decrease in tire air-pressure based on relative comparison between detected wheel rotational velocities;

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 an arbitrary number of judgment values stored in the average preparation buffer and the number thereof into the nonvolatile memory at 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; and

judging means for obtaining an 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, thereby judging whether or not a decrease in tire air-pressure occurs.