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

• US 6,396,396 B2
• Filed: 12/08/2000
• Issued: 05/28/2002
• Est. Priority Date: 12/09/1999
• Status: Expired due to Fees

• 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
• Primary Examiner(s): TWEEL JR, JOHN ALEXANDER
• Application Number:
  US09/731,732
• Publication Number:
  US 20010003437A1
• Time in Patent Office: 536 Days
• Field of Search: 340/442,441 73/146.7,146.2,146.5 116/34 R
• 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 and apparatus for judging a decrease in internal pressure of a tire attached to a four-wheeled vehicle and for accordingly generating an 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, 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 that for the normal running condition of the vehicle in the case no decompression is judged. It is thus possible to detect a condition in which a large decompressed condition exists at an early stage before running begins so that it is possible to improve the accuracy of detecting decompression.

Claims

1. A method for judging a decrease in internal pressure o a tire attached to a four-wheeled vehicle and for generating an 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, judging decompression 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 that for the normal running condition of the vehicle in the case no decompression is judged.

2. An apparatus for judging a decrease in internal pressure of a tire attached to a four-wheeled vehicle and for accordingly generating an alarm, comprising a velocity detecting means for detecting a velocity signal of respective tires, a judging means for performing calculating processes of a decompression judgment 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 that for the normal running condition of the vehicle in the case no decompression is judged.

3. A method for judging a decrease in internal pressure o a tire attached to a four-wheeled vehicle and for generating an alarm, comprising the steps of setting a threshold of judging decompression to be larger immediately after switching an ignition key ON when compared to a threshold of 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 the number of data used for judging decompression than compared to the number of data which might be incorporated during the short decompression judging time, in the case it is judged that the vehicle is running on a bad road.

4. An apparatus for judging a decrease in internal pressure of a tire attached to a four-wheeled vehicle and for accordingly generating an alarm, comprising a velocity detecting means for detecting a velocity signal of respective tires, a judging means for performing calculating processes of a decompression judgment 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 the 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 the case it is judged that the vehicle is running on a bad road.