Air pressure detection device for tire

• US 6,664,890 B2
• Filed: 01/30/2002
• Issued: 12/16/2003
• Est. Priority Date: 01/30/2001
• Status: Expired due to Fees

• Current Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Original Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Inventors: Harada, Tomoyuki, Yamagiwa, Toshio
• Primary Examiner(s): Lee, Benjamin C.
• Assistant Examiner(s): PHAM, LAM P
• Application Number:
  US10/058,277
• Publication Number:
  US 20020105420A1
• Time in Patent Office: 685 Days
• Field of Search: 340/442, 340/445-448, 340/427, 340/425.5, 731/465, 731/462
• US Class Current: 340/442
• CPC Class Codes: B60C 23/006 having two wheels only
• CPC Class Codes: B60C 23/0408 transmitting the signals by non-mechanical means from the wheel or tyre to a vehicle body mounted receiver

Abstract

A vehicle is provided with an air pressure detection device for a tire which includes a temperature sensor for measuring the temperature of a tire and an air pressure sensor for measuring the air pressure of the tire. A reduced air pressure arithmetic portion is provided for calculating a reduced air pressure Pm from the temperature Tx measured by the temperature sensor and the air pressure Px measured by the air pressure sensor by the formula set forth below. An alarm signal generating portion is provided for generating an alarm signal when the reduced air pressure Pm calculated by the reduced air pressure arithmetic portion is decreased to or below a first threshold value Pa.

Pm=Px−K(Tx−T0)

The condition where the tire air pressure is lowered to or below a threshold value determined based on a recommended air pressure can be accurately detected, and an alarm can be issued, without being affected by tire temperature rise or temperature variations.

Claims

1. An air pressure detection device for a tire comprising:

an air pressure sensor for measuring the air pressure of a said tire;

a temperature sensor for measuring the temperature at a predetermined portion in said tire;

a reduced air pressure arithmetic means for calculating a reduced air pressure Pm from the air pressure measured by said air pressure sensor and the temperature measured by said temperature sensor, the reduced air pressure Pm being calculated by the following formula;

2. The air pressure detection device for a tire as set forth in claim 1, wherein said alarm signal generating means generates said alarm signal when a decrease of the air pressure of said tire over a unit time measured by said air pressure sensor is decreased below a predetermined second threshold value.

3. The air pressure detection device for a tire as set forth in claim 2, and further including a timer for timing the intervals of the decrease in the air pressure over said unit time.

4. The air pressure detection device for a tire as set forth in claim 1, and further including a comparing means for comparing the reduced air pressure from said reduced air pressure arithmetic means and said predetermined first threshold value.

5. The air pressure detection device for a tire as set forth in claim 4, and further including a threshold value storage means for storing a plurality of threshold values commensurate with a plurality of tires and tire conditions.

6. The air pressure detection device for a tire as set forth in claim 5, wherein the reduced air pressure arithmetic means, the threshold value storage means, the comparing means and the alarm signal generating means form a control unit for receiving air pressure and temperature from a tire.

7. An air pressure detection device for a tire comprising:

an air pressure sensor for measuring air pressure of said tire;

a temperature sensor for measuring temperature of said tire;

means for calculating a reduced/increased air pressure Pm as compared to the air pressure measured by said air pressure sensor and a reduced/increased temperature measured by said temperature sensor, the reduced air pressure Pm being calculated by the following formula;

8. The air pressure detection device for a tire as set forth in claim 7, wherein said alarm signal generating means generates said alarm signal when a decrease of the air pressure of said tire over a time unit measured by said air pressure sensor is decreased below a predetermined second threshold value.

9. The air pressure detection device for a tire as set forth in claim 8, and further including a timer for timing the intervals of the decrease in the air pressure over said unit time.

10. The air pressure detection device for a tire as set forth in claim 7, and further including a comparing means for comparing the reduced air pressure from said means for calculating a reduced/increased air pressure and said predetermined first threshold value.

11. The air pressure detection device for a tire as set forth in claim 10, and further including a threshold value storage means for storing a plurality of threshold values commensurate with a plurality of distinct tires and tire conditions.

12. The air pressure detection device for a tire as set forth in claim 11, wherein the means for calculating a reduced/increased air pressure, the threshold value storage means, the comparing means and the alarm signal generating means form a control unit for receiving air pressure and temperature from a tire.