Testing device apparatus and method for tire pressure of automotive vehicle wheels

• US 4,567,460 A
• Filed: 12/20/1982
• Issued: 01/28/1986
• Est. Priority Date: 12/24/1981
• Status: Expired due to Fees

• Current Assignee: Bayerische Motoren Werke AG
• Original Assignee: Bayerische Motoren Werke AG
• Inventors: Gebler, Eugen
• Primary Examiner(s): Groody, James J.
• Application Number:
  US06/451,274
• Time in Patent Office: 1,135 Days
• Field of Search: 73/146.4, 73/146.5, 340/58, 340/626, 340/52 R, 116/34 R, 200/61.22, 200/61.23, 200/61.24, 200/61.25
• US Class Current: 340/442
• CPC Class Codes: B60C 23/06 Signalling devices actuated by deformation of the tyre , e.g. tyre mounted deformation sensors or indirect determination of tyre deformation based on wheel speed, wheel-centre to ground distance or inclination of wheel axle

Abstract

In a testing apparatus and method for the tire pressure of automotive vehicle wheels, individual testing units for each wheel are arranged outside of the wheels at their suspension members. Only a single wheel is provided with an additional calibrating means for an exact tire pressure determination, in order to provide a calibrating standard for the relative measurement of the tire pressures of the wheels which can be performed with the aid of the testing units to produce a warning indication of low tire pressure.

Claims

1. A testing apparatus for wheeled road vehicles having suspension members for the wheels comprising

first means mounted at the suspension members for sensing a characteristic of the suspension member adjacent each wheel with respect to the road,

calibration means for sensing tire pressure of at least the tire of one of said wheels, and

second means responsive to an output signal from said first means and to a signal from said calibration means for producing an output warning signal.

2. A testing apparatus in accordance with claim 1, wherein said calibration means comprises

means for measuring inductance, and

means attached to a wheel for varying the measured indication of inductance in response to a tire pressure of said wheel.

3. A testing apparatus in accordance with claim 2, wherein the means attached to the wheel is attached to a rear wheel.

4. A testing apparatus in accordance with claim 1, wherein said calibration means comprises

first coil means mounted at a vehicle wheel of variable inductance for sensing tire pressure, and

second coil means mounted at a suspension member of said vehicle for generating a signal representing a change in tire pressure.

5. A testing apparatus in accordance with claim 1, wherein the first means comprises

means for measuring acceleration.

6. A testing apparatus in accordance with claim 1, wherein said second means comprises

means for determining a change in air pressure in a tire of a wheel in response to a change in oscillation frequency of said characteristic.

7. A testing apparatus in accordance with claim 1, wherein said second means comprises

means for determining a change in air pressure in a tire of a wheel in response to a change in amplitude of said characteristic.

8. A testing apparatus in accordance with claim 1, further comprising

third means in response to said output signal and a signal representing an established limit for generating a warning signal indicating a low tire pressure.

9. A method for determining air pressure of a tire on a wheeled vehicle having a plurality of wheels and a vehicle body comprising

sensing at said plurality of wheels a characteristic of vehicle motion with respect to a road surface to produce a first signal,

sensing additionally a characteristic of motion of one of said wheels with respect to the vehicle body to produce a second signal, and

generating a warning signal in response to said first and second signals.

10. A method in accordance with claim 9, wherein the generating step comprises

comparing said first and second sensed signals to produce a difference signal, and

comparing said difference signal with a signal representing a tire pressure limit to produce said warning signal.