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

• US 20030187607A1
• Filed: 04/02/2003
• Published: 10/02/2003
• Est. Priority Date: 04/02/2002
• Status: Active Grant

• Current Assignee: Sumitomo Rubber Industries Limited
• Original Assignee: Sumitomo Rubber Industries Limited
• Inventors: Oshiro, Yuji
• Granted Patent: US 6,804,623 B2
• Time in Patent Office: Days
• US Class Current: 702/140
• 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 in which decrease in internal pressure of a tire is detected on the basis of rotational information obtained from tires attached to a vehicle. The method includes the steps of; detecting and storing rotational information of the respective tires; calculating and storing a slip rate; calculating and storing a correction coefficient for correcting a difference in effective rolling radii owing to initial differences between right and left front tires, a correction coefficient between right and left rear tires and a correction coefficient between front tires and rear tires; comparing a correction coefficient between front tires and rear tires with a correction coefficient between the front tires and the rear tires preliminarily obtained when at normal internal pressure; and judging simultaneous decompression of two wheel tires of both front wheels or simultaneous decompression of two wheel tires of both rear wheels on the basis of a relationship between a value obtained through comparison of the two correction coefficients and a specified threshold.

Claims

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

detecting and storing rotational information of the respective tires;

calculating and storing a slip rate;

calculating and storing a correction coefficient for correcting a difference in effective rolling radii owing to initial differences between right and left front tires, a correction coefficient for correcting a difference in effective rolling radii owing to initial differences between right and left rear tires and a correction coefficient for correcting a difference in effective rolling radii owing to initial differences between front tires and rear tires;

comparing a correction coefficient between front tires and rear tires obtained from rotational information which are gained from tires attached to the vehicle when performing cornering running other than freewheeling with a correction coefficient between the front tires and the rear tires preliminarily obtained when at normal internal pressure; and

judging simultaneous decompression of two wheel tires of both front wheels or simultaneous decompression of two wheel tires of both rear wheels on the basis of a relationship between a value obtained through comparison of the two correction coefficients and a specified threshold.

2. The method of claim 1, wherein the method further includes the steps of calculating a velocity of the vehicle, calculating a turning radius of the vehicle, and calculating a lateral directional acceleration of the vehicle.

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

rotational information detecting means which detects the rotational information of the respective tires;

rotational information storing means which stores the rotational information of the respective tires;

slip rate calculating and storing means which calculates and stores a slip rate;

correction coefficient calculating and storing means which calculates and stores a correction coefficient for correcting a difference in effective rolling radii owing to initial differences between right and left front tires, a correction coefficient for correcting a difference in effective rolling radii owing to initial differences between right and left rear tires and a correction coefficient for correcting a difference in effective rolling radii owing to initial differences between front tires and rear tires;

comparing means which compares a correction coefficient between front tires and rear tires obtained from rotational information which are gained from tires attached to the vehicle when performing cornering running other than freewheeling with a correction coefficient between the front tires and the rear tires preliminarily obtained when at normal internal pressure; and

decompression judging means which judges simultaneous decompression of two wheel tires of both front wheels or simultaneous decompression of two wheel tires of both rear wheels on the basis of a relationship between a value obtained through comparison of the two correction coefficients and a specified threshold.

4. The apparatus of claim 3, wherein the apparatus further includes a means for calculating a velocity of the vehicle, a means for calculating a turning radius of the vehicle, and a means for calculating a lateral directional acceleration of the vehicle.

5. A program for judging decompression of a tire, in which for judging decrease in air-pressure of a tire, a computer is made to function as rotational information storing means which stores the rotational information of the respective tires;

slip rate calculating and storing means which calculates and stores the slip rate;

correction coefficient calculating and storing means which calculates and stores a correction coefficient for correcting a difference in effective rolling radii owing to initial differences between right and left front tires, a correction coefficient for correcting a difference in effective rolling radii owing to initial differences between right and left rear tires and a correction coefficient for correcting a difference in effective rolling radii owing to initial differences between front tires and rear tires;

comparing means which compares a correction coefficient between front tires and rear tires obtained from rotational information which are gained from tires attached to the vehicle when performing cornering running other than freewheeling with a correction coefficient between the front tires and the rear tires preliminarily obtained when at normal internal pressure; and

decompression judging means which judges simultaneous decompression of two wheel tires of both front wheels or simultaneous decompression of two wheel tires of both rear wheels on the basis of a relationship between a value obtained through comparison of the two correction coefficients and a specified threshold.

6. The program of claim 5, wherein the computer is made to function also as a means for calculation a velocity of the vehicle, a means for calculating a turning radius of the vehicle, and a means for calculating a lateral directional acceleration of the vehicle.