Method and apparatus for detecting decrease in tire air-pressure and program for judging decompression of tire

• US 20040046650A1
• Filed: 09/04/2003
• Published: 03/11/2004
• Est. Priority Date: 09/06/2002
• Status: Active Grant

• Current Assignee: Sumitomo Rubber Industries Limited
• Original Assignee: Sumitomo Rubber Industries Limited
• Inventors: Yanase, Minao
• Granted Patent: US 7,032,442 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

A method for detecting decrease in tire air-pressure includes the steps of: detecting rotational angular velocities of respective tires; calculating an initial correction coefficient for a ratio of right and left wheels; terminating initialization of a first stage at a point of time when the initial correction coefficient has been calculated for performing a provisional judgment of decompression; calculating an initial correction coefficient for a ratio of front and rear wheels; and terminating initialization of a second stage at a point of time when the initial correction coefficient has been calculated for performing normal judgement of decompression. Detection of decompression when performing running including mostly straight-ahead running such as driving in an urban area might be made at an early stage and at high accuracy to thereby improve the performance of the system.

Claims

1. A method for detecting decrease in tire air-pressure, which detects decrease in tire air-pressure on the basis of rotational information obtained from tires attached to a four-wheeled vehicle, the method comprising the steps of:

detecting rotational angular velocities of respective tires;

calculating an initial correction coefficient for a ratio of right and left wheels from among the rotational angular velocities of respective tires;

terminating initialization of a first stage at a point of time when the initial correction coefficient has been calculated for performing a provisional judgment of decompression;

calculating an initial correction coefficient for a ratio of front and rear wheels from among the rotational angular velocities of respective tires; and

terminating initialization of a second stage at a point of time when the initial correction coefficient has been calculated for performing normal judgment of decompression.

2. A method for detecting decrease in tire air-pressure, which detects decrease in tire air-pressure on the basis of rotational information obtained from tires attached to a four-wheeled vehicle, the method comprising the steps of:

detecting rotational angular velocities of respective tires;

calculating an initial correction coefficient for a ratio of front and rear wheels and an initial correction coefficient for a ratio of right and left wheels from among the rotational angular velocities of respective tires;

performing provisional judgment of decompression at a point of time when the initial correction coefficient for the ratio of right and left wheels has been calculated; and

performing normal judgment of decompression by using the initial correction coefficient for the ratio of right and left wheels and the initial correction coefficient for the ratio of front and rear wheels.

3. An apparatus for detecting decrease in tire air-pressure, which detects decrease in tire air-pressure on the basis of rotational information obtained from tires attached to a four-wheeled vehicle, the apparatus comprising:

rotational information detecting means which detect rotational angular velocities of respective tires;

a first calculating means which calculates an initial correction coefficient for a ratio of right and left wheels from among the rotational angular velocities of respective tires;

a provisional decompression judging means which terminates completes initialization of a first stage at a point of time when the initial correction coefficient has been calculated for performing a provisional judgment of decompression;

a second calculating means which calculates an initial correction coefficient for a ratio of front and rear wheels from among the rotational angular velocities of respective tires; and

a normal decompression judging means which terminates completes initialization of a second stage at a point of time when the initial correction coefficient has been calculated for performing normal judgment of decompression.

4. An apparatus for detecting decrease in tire air-pressure, which detects decrease in tire air-pressure on the basis of rotational information obtained from tires attached to a four-wheeled vehicle, the apparatus including comprising:

rotational information detecting means which detect rotational angular velocities of respective tires;

a calculating means which calculates an initial correction coefficient for a ratio of front and rear wheels and an initial correction coefficient for a ratio of right and left wheels from among the rotational angular velocities of respective tires;

a provisional decompression judging means which performs provisional judgment of decompression at a point of time when the initial correction coefficient for the ratio of right and left wheels has been calculated; and

a normal decompression judging means which performs normal judgment of decompression by using the initial correction coefficient for the ratio of right and left wheels and the initial correction coefficient for the ratio of front and rear wheels.

5. A program for judging decompression of a tire in which for judging decrease in tire air-pressure, a computer is made to function as a first calculating means which calculates an initial correction coefficient for a ratio of right and left wheels from among the rotational angular velocities of respective tires;

a provisional decompression judging means which terminates initialization of a first stage at a point of time when the initial correction coefficient has been calculated for performing a provisional judgment of decompression;

a second calculating means which calculates an initial correction coefficient for a ratio of front and rear wheels from among the rotational angular velocities of respective tires; and

a normal decompression judging means which terminates initialization of a second stage at a point of time when the initial correction coefficient has been calculated for performing normal judgment of decompression.

6. A program for judging decompression of a tire in which for judging decrease in tire air-pressure, a computer is made to function as a calculating means which calculates an initial correction coefficient for a ratio of front and rear wheels and an initial correction coefficient for a ratio of right and left wheels from among rotational angular velocities of respective tires;

a provisional decompression judging means which performs provisional judgment of decompression at a point of time when the initial correction coefficient for the ratio of right and left wheels has been calculated; and

normal decompression judging means which performs normal judgment of decompression by using the initial correction coefficient for the ratio of right and left wheels and the initial correction coefficient for the ratio of front and rear wheels.