Method and device for detecting a deflated tire by comparing angular velocity and forward/backward speed data with a data table

• US 5,442,331 A
• Filed: 12/20/1993
• Issued: 08/15/1995
• Est. Priority Date: 12/21/1992
• Status: Expired due to Term

• Current Assignee: Sumitomo Rubber Industries Limited
• Original Assignee: Sumitomo Rubber Industries Limited
• Inventors: Yanase, Minao, Kishimoto, Yoshikazu
• Primary Examiner(s): Chilcot, Jr., Richard E.
• Assistant Examiner(s): Felber, Joseph L.
• Application Number:
  US08/169,397
• Time in Patent Office: 603 Days
• Field of Search: 340/444, 73/146.2, 73/146.3, 73/146.4, 73/146.5
• 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 detecting a deflated condition of a tire, comprises the steps of (a) detecting the angular velocity of each wheel, (b) producing a signal proportional to the angular velocity detected, (c) detecting acceleration of the vehicle in a forward or backward direction, (d) obtaining a speed of the vehicle in the forward or backward direction by integrating the detected acceleration, (e) producing a signal proportional to the obtained speed of the vehicle in the forward or backward direction, and (f) arithmetically processing the signals produced in steps (b) and (e). In step (f), the angular velocity of each wheel at the speed in the forward or backward direction obtained in step (d) is obtained from a normal wheel angular velocity table previously prepared; and the result is compared with the angular velocity detected in step (a), and if the difference therebetween is within the range of 0.05% to 0.60%, a device for warning of a deflated tire is operated.

Claims

1. A method for detecting a deflation condition of a tire mounted on a wheel of a vehicle, comprising the steps of:

(a) detecting angular velocity of each wheel,

(b) producing signals proportional to the detected angular velocities,

(c) detecting accelerations of the vehicle in a forward or backward direction,

(d) obtaining a speed in the forward or backward direction by integrating the detected accelerations,

(e) producing a signal proportional to the obtained speed in the forward or backward direction,

(f) arithmetically processing the signals produced in steps (b) and (e),

(g) measuring throttle opening, as a proportion of maximum opening differentiating the measured values with respect to tire and monitoring the differentiated values of throttle opening; and

(h) invalidating the data of angular velocity of each wheel when the differentiated value of throttle opening exceeds 100%/sec,

wherein the step (f) comprises;

obtaining, from a previously prepared table of wheel angular velocities under normal conditions, a wheel angular velocity at the speed in the forward or backward direction which is obtained in step (d),

comparing the wheel angular velocity at the speed in the forward or backward direction with the angular velocity of each wheel obtained in the step (a), and

operating a device which warns of the deflation condition of the at least one tire when the respective differences between the wheel angular velocity at the speed in the forward or backward direction and the angular velocity of each wheel detected in the step (a) range from 0.05% to 0.60% of wheel angular velocity in the table.

2. The method of claim 1, further comprising the steps of:

(i) directly measuring and monitoring acceleration in a lateral direction, said lateral direction being transverse to the forward and backward directions, and

(j) invalidating the data of angular velocity of each wheel when an absolute value of the acceleration in the lateral direction exceeds 0.06 g.

3. The method of claim 1, further comprising the steps of:

(k) directly measuring and monitoring acceleration of the vehicle in the forward or backward direction, and

(l) invalidating the data of angular velocity of each wheel when an absolute value of the acceleration, in the forward or backward direction exceeds 0.03 g.

4. The method of claim 1, further comprising the steps of:

(m) invalidating the data of angular velocity of each wheel when a braking pedal is actuated.

5. A device for detecting a deflation condition of a tire mounted on a wheel of a vehicle comprising:

angular velocity detecting means for detecting an angular velocity of each wheel,

angular velocity signal producing means for producing signals proportional to the detected angular velocities,

acceleration detecting means for detecting accelerations of the vehicle in a forward or backward direction,

integrating means for integrating the detected acceleration and obtaining a speed in the forward or backward directions,

speed signal producing means for producing a signal proportional to the obtained speed in the forward or backward direction,

arithmetically processing means for arithmetic processing the signals from the angular velocity signal producing means and the speed signal producing means,

means for measuring throttle opening as a proportion of maximum opening, differentiating the measured value, and monitoring the differentiated value, and

means for invalidating the data of angular velocity of each wheel when the differentiated value of throttle opening exceeds 100%/sec,

wherein the arithmetic processing means

obtains, from a table of wheel angular velocities in normal condition, which is prepared previously, a wheel angular velocity at the speed in the forward or backward direction which is obtained by the integrating means,

compares the wheel angular velocity at the speed in the forward or backward direction with the angular velocity of each wheel obtained in the angular velocity detecting means, and

operates a device which warns of the deflation condition of the at least one tire when the respective difference between the wheel angular velocity at the speed in the forward or backward direction and the angular velocity of each wheel detected in the angular velocity detecting means range from 0.05% to 0.60% of wheel angular velocity in the table.

6. The device of claim 5, further comprising:

means for directly measuring and monitoring acceleration of the vehicle in a lateral direction, said lateral direction being transverse to the forward and backward directions, and means for invalidating the data of angular velocity of each wheel when an absolute value of the acceleration in the lateral direction exceeds 0.06 g.

7. The device of claim 5, further comprises:

means for directly measuring and monitoring acceleration of a vehicle in the forward or backward direction, and

means for invalidating the data of angular velocity of each wheel when an absolute value of the acceleration in the forward or backward direction exceeds 0.03 g.

8. The device of claim 5, further comprises:

means for invalidating the data of angular velocity of each wheel a braking pedal is actuated.