Method and apparatus for alarming decrease in tire air-pressure

• US 20040021557A1
• Filed: 07/30/2002
• Published: 02/05/2004
• Est. Priority Date: 07/30/2002
• 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: Yanase, Minao
• Granted Patent: US 6,774,776 B2
• Time in Patent Office: Days
• US Class Current: 340/442
• CPC Class Codes: B60C 23/061 by monitoring wheel speed measuring distance traversed on the ground by vehicles G01C22/00

Abstract

A method for alarming decrease in tire air-pressure, in which rotational numbers of four tires are detected for judging whether any of the tire air-pressures is decreased or not, and issuing an alarm in case an internal pressure of a tire is decreased. In an equation for calculating a judged value for detecting deflation of a tire, correction factor function values including a first factor related to lateral acceleration of the vehicle and a second factor related to lateral acceleration and front and rear wheel ratios are subtracted from actually measured values when performing actual running of the vehicle with the tires being set to specific air-pressures, and the first and second factors are so calculated that a result of subtraction is approximately close to zero and are stored. It is possible to improve accuracy of detection of deflations of tires by automatically obtaining factors for turning correction after mounting the tires to the vehicle.

Claims

1. A method for alarming decrease in tire air-pressure, in which rotational numbers of four tires are detected for judging, on the basis of the detected rotational numbers, whether any of the tire air-pressures is decreased or not, and issuing an alarm in case an internal pressure of a tire is decreased,

wherein in an equation for calculating a judged value for detecting deflation of a tire upon comparing differences of two diagonal sums, correction factor function values including a first factor related to lateral acceleration of the vehicle and a second factor related to lateral acceleration and front and rear wheel ratios are subtracted from actually measured values when performing actual running of the vehicle with the tires being set to specific air-pressures, and the first and second factors are so calculated that a result of subtraction is approximately close to zero and are stored.

2. An apparatus for alarming decrease in tire air-pressure, in which rotational numbers of four tires are detected for judging, on the basis of the detected rotational numbers, whether any of the tire air-pressures is decreased or not, and issuing an alarm in case an internal pressure of a tire is decreased, the apparatus comprising:

a speed detecting means for detecting wheel speeds of the respective tires;

a calculating means for calculating and processing a judged value for deflation in which differences between two diagonal sums of rotational numbers of front tires and rotational numbers of rear tires are compared on the basis of the rotational numbers which are obtained from the wheel speeds detected by the speed detecting means; and

an optimal factor calculating means in which correction factor function values including a first factor related to lateral acceleration of the vehicle and a second factor related to lateral acceleration and front and rear wheel ratios are calculated by subtracting them from actually measured values when performing actual running of the vehicle with the tires being set to specific air-pressures, and the first and second factors are so calculated that a result of substraction is approximately close to zero and are stored.