Apparatus and method for alarming decrease in tire air-pressure

• US 20020057196A1
• Filed: 09/20/2001
• Published: 05/16/2002
• Est. Priority Date: 09/20/2000
• Status: Active Grant

• Current Assignee: Sumitomo Electric Industries Limited (Sumitomo Corporation), Sumitomo Rubber Industries Limited
• Original Assignee: Sumitomo Electric Industries Limited (Sumitomo Corporation), Sumitomo Rubber Industries Limited
• Inventors: Sugisawa, Toshifumi
• Granted Patent: US 6,504,475 B2
• Time in Patent Office: Days
• US Class Current: 340/444
• CPC Class Codes: B60C 23/061 by monitoring wheel speed measuring distance traversed on the ground by vehicles G01C22/00

Abstract

An apparatus for alarming decrease in tire air-pressure which detects the decrease in internal pressure of the tire based on wheel speed information obtained from wheels of a vehicle and accordingly alarms a driver. The apparatus comprises: a wheel speed information detecting means, a memory means for storing the wheel speed information of the respective tires, a calculating means for calculating a judged value based on a vehicle velocity and wheel speed information, and a judging means for determining a decrease in tire air-pressure based on correlation of the vehicle velocity and an outer diameter of the tire at the time of performing high-speed running. It is possible to determine a decompression of a tire based on the correlation also in case the judged value will not become large owing to increased influence of centrifugal force during high-speed running even though a tire is in a decompressed condition.

Claims

1. An apparatus for alarming decrease in tire air-pressure which detects the decrease in internal pressure of the tire based on wheel speed information obtained from wheels of a vehicle and accordingly alarms a driver, comprising:

a wheel speed information detecting means for detecting wheel speed information of the respective tires, a memory means for storing the wheel speed information of the respective tires, a calculating means for calculating a judged value based on a vehicle velocity and wheel speed information of the respective tires, and a judging means for determining a decrease in tire air-pressure based on correlation of the vehicle velocity and an outer diameter of the tire at the time of performing high-speed running.

2. The apparatus of claim 1, wherein, in case there is correlation between an outer diameter of the tire and a wheel speed of a wheel of the tire, the judging means obtains a judged value for judging decompression which is a ratio between a value obtained by subtracting a sum of wheel speeds of one pair of wheels located on one diagonal line from a sum of wheel speeds of the other pair of wheels located on the other diagonal line, and an average value of the two sums;

and determines the decrease of tire air-pressure based on correlation between the judged value and a vehicle velocity at a high speed running.

3. The apparatus of claim 2, wherein correlation coefficient in the correlation between the judged value and the vehicle velocity is in the range of 0.8 to 1 or −

0.8 to −

1.

4. A method for alarming decrease in tire air-pressure which detects the decrease in internal pressure of the tire based on wheel speed information obtained from wheels of a vehicle and accordingly alarms a driver, comprising the steps of:

detecting wheel speed information of the respective tires, storing the wheel speed information of the respective tires, calculating a judged value based on a vehicle velocity and wheel speed information of the respective tires, and determining a decrease in tire air-pressure based on correlation of the vehicle velocity and an outer diameter of the tire at the time of performing high-speed running.

5. The method of claim 4, wherein the decrease in tire air-pressure is judged by obtaining a judged value for judging decompression which is a ratio between a value obtained by subtracting a sum of wheel speeds of one pair of wheels located on one diagonal line from a sum of wheel speeds of the other pair of wheels located on the other diagonal line, and an average value of the two sums;

and determining the decrease of tire air-pressure based on correlation between the judged value and a vehicle velocity at a high speed running.

6. The method of claim 5, wherein correlation coefficient in the correlation between the judged value and the vehicle velocity is in the range of 0.8 to 1 or −

0.8 to −

1.