Method for alarming decrease in tire air-pressure and apparatus used therefor

• US 20010003437A1
• Filed: 12/08/2000
• Published: 06/14/2001
• Est. Priority Date: 12/09/1999
• 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, Oshiro, Yuji
• Granted Patent: US 6,396,396 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 alarming decrease in tire air-pressure for judging a decrease in internal pressure of a tire attached to a four-wheeled vehicle and for accordingly generating alarm. A threshold for judging decompression is set to be larger immediately after switching an ignition key ON when compared to a threshold for the vehicle in a normal running condition, and decompression is judged in a decompression judging time which is shorter than a time for the vehicle in a normal running condition. The threshold for judging decompression and the decompression judging time are returned to those for the normal running condition of the vehicle in case no decompression is judged. An apparatus used for the method is also disclosed. It is possible to detect a condition in which a large decompressed condition exists at an early stage before starting running so that it is possible to improve the accuracy of detecting decompression.

Claims

1. A method for alarming decrease in tire air-pressure for judging a decrease in internal pressure of a tire attached to a four-wheeled vehicle and for accordingly generating alarm, wherein a threshold for judging decompression is set to be larger immediately after switching an ignition key ON when compared to a threshold for the vehicle in a normal running condition, decompression is judged in a decompression judging time which is shorter than a time for the vehicle in a normal running condition, and the threshold for judging decompression and the decompression judging time are returned to those for the normal running condition of the vehicle in case no decompression is judged.

2. An apparatus for alarming decrease in tire air-pressure for alarming decrease in tire air-pressure for judging a decrease in internal pressure of a tire attached to a four-wheeled vehicle and for accordingly generating alarm, comprising a velocity detecting means for detecting a velocity signal of respective tires, a judging means for performing calculating processes of a decompression judgement value for comparing a difference of two diagonal sums of rotational information of front wheel tires and rotational information of rear wheel tires based on rotational information obtained from the velocity signals detected by the velocity detecting means, an initial judging means for setting a threshold for judging decompression to be larger immediately after switching an ignition key ON when compared to a threshold for the vehicle in a normal running condition and judging decompression in a decompression judging time which is shorter than a time for the vehicle in a normal running condition, and a returning means for returning the threshold for judging decompression and the decompression judging time to those for the normal running condition of the vehicle in case no decompression is judged.

3. A method for alarming decrease in tire air-pressure for judging a decrease in internal pressure of a tire attached to a four-wheeled vehicle and for accordingly generating alarm, comprising the steps of setting a threshold for judging decompression to be larger immediately after switching an ignition key ON when compared to a threshold for the vehicle in a normal running condition and judging decompression in a decompression judging time which is shorter than a time for the vehicle in a normal running condition;

judging whether the vehicle is running on a bad road while a decompressed condition is judged during the short decompression judging time; and

increasing a number of data used for judging decompression than compared to a number of data which might be incorporated during the short decompression judging time in case it is judged that the vehicle is running on a bad road.

4. An apparatus for alarming decrease in tire air-pressure for alarming decrease in tire air-pressure for judging a decrease in internal pressure of a tire attached to a four-wheeled vehicle and for accordingly generating alarm, comprising a velocity detecting means for detecting a velocity signal of respective tires, a judging means for performing calculating processes of a decompression judging value for comparing a difference of two diagonal sums of rotational information of front wheel tires and rotational information of rear wheel tires based on rotational information obtained from the velocity signals detected by the velocity detecting means, an initial judging means for setting a threshold for judging decompression to be larger immediately after switching an ignition key ON when compared to a threshold for the vehicle in a normal running condition and judging decompression in a decompression judging time which is shorter than a time for the vehicle in a normal running condition, a bad road judging means for judging whether the vehicle is running on a bad road while a decompressed condition is judged during the short decompression judging time, and a data updating means for increasing a number of data used for judging decompression than compared to a number of data which might be incorporated during the short decompression judging time in case it is judged that the vehicle is running on a bad road.