TIRE PRESSURE MONITORING SYSTEM

• US 3,873,965 A
• Filed: 04/18/1974
• Issued: 03/25/1975
• Est. Priority Date: 04/18/1974
• Status: Expired due to Term

• Current Assignee: George E. Garcia
• Original Assignee: George E. Garcia
• Inventors: Garcia, George E.
• Primary Examiner(s): Waring, Alvin H.
• Application Number:
  US05/462,082
• Time in Patent Office: 341 Days
• Field of Search: 340/58 200/61.22,61.25 325/111,117
• US Class Current: 340/447
• CPC Class Codes: B60C 23/0433 Radio signals

Abstract

A tire pressure monitoring system for providing an indication in a vehicle that one of its tires is losing its normal inflation pressure. The system comprises a pressure responsive actuator within each tire in the system including an extensible portion that is normally retracted and shielded when tire pressure is normal. The extensible portion of the actuator is covered with a material sensitive to R.F. energy. Mounted adjacent to each tire of the system is an R.F. energy transmitter directed toward the tire and an accompanying receiver. Loss of pressure in a tire causes the actuator to extend and expose its R.F. sensitive portion, thereby causing a signal disturbance in the R.F. receiver which is connected to an indicator in the vehicle.

Claims

1. For use on a vehicle having a plurality of inflatable tires, a tire pressure monitoring system comprising:

a pressure sensitive device mounted within each of the tires, each said device having a normally shielded portion thereof which is extendable in response to a reduction in pressure within the tire and around the device, saiD extendable portion having a surface that is sensitive to R.F. energy;

an R.F. transmitter unit mounted on said vehicle adjacent each of its tires and positioned so as to direct a beam of R.F. energy toward an adjacent tire and said pressure sensitive device therein;

antenna means for sensing R.F. energy that is reflected from the tire;

receiver means connected to said antenna means for detecting the change in the reflected R.F. energy from a tire when its said device is activiated to extend its R.F. sensitive portion; and

display means connected to said receiver means for providing an indication of the reduced tire pressure when its said device is activated.

2. The tire pressure monitoring system described in claim 1 wherein said pressure sensitive device comprises a small vessel having an inlet-check valve for allowing air to enter the vessel at the same pressure as in the tire, said extendable portion comprising a series of bellow-like folds, normally surrounding a shield means, which extend from said shield means when the pressure inside the vessel exceeds the pressure outside of it.

3. The tire pressure monitoring system described in claim 1 wherein said R.F. transmitter unit and said antenna unit for each tire is mounted on the vehicle adjacent the tire.

4. The tire pressure monitoring system described in claim 1 wherein said receiver means comprises an amplifying means for receiving signals from said receiver-antenna unit, means connected to said amplifying means for detecting a change in signal level from a predetermined level normally received when said pressure sensitive device has not been activated, and means for amplifying and filtering the detected signal for driving an indicator means on said display means.

5. A system for monitoring the pressure in a confined space comprising:

a pressure sensitive device mounted within said confined space, said device having a normally shielded portion thereof which is extendable in response to a reduction in pressure within the space and around the device, said extendable portion having a surface that is sensitive to a beam of energy applied to said normally shielded portion when it is extended;

an energy transmission means positioned so as to direct a beam of energy toward said pressure sensitive device within the confined space;

signal sensitive means adjacent said transmission means for receiving energy that is reflected from said device and surrounding structure;

signal processing means connected to said signal sensitive means for detecting the change in said reflected energy from said device when it is activated to extend its sensitive portion; and

display means connected to said signal processing means for providing an indication of the reduced pressure within said confined space when said device is activated.

6. The system as described in claim 5 wherein said energy transmission means comprises an R.F. signal transmitter and said signal sensitive means includes an R.F. sensitive antenna.

7. The system as described in claim 5 wherein said confined space is an inflatable tire mounted on a vehicle, said pressure sensitive device being located within said tire and said energy transmission means being located outside of said tire.

8. The system as described in claim 7 wherein said vehicle has a body with fenders and a dashboard and said energy transmission means and said signal sensitive means for each tire are mounted adjacent to each other on the inside of a fender for the tire, said display means being mounted on said dashboard.

9. The system as described in claim 7 wherein said signal processing means comprises a first R.F. amplifying means connected to said signal sensitive means, detector means connected to said first amplifying means, second amplifying means connected to said detector means, filtering means for isolating signals of a preselected characteristic and rectifier means for conditioning the detected and filtered signaLs for actuating by said display means.

10. The pressure monitoring system described in claim 5 wherein said pressure sensitive device comprises a small vessel having an inlet-check valve for allowing air to enter the vessel at the same pressure as in the tire, said extendable portion comprising a series of bellows-like folds, shielding means normally surrounding said extendable portion, said extendable portion being movable outwardly from said shield means when the pressure inside the vessel exceeds the pressure outside of it.

11. The pressure monitoring system described in claim 10 including a surface coating on said extendable portion of said pressure sensitive device which is sensitive to and causes changes in R.F. energy that impinges upon said coating.

12. The pressure monitoring system described in claim 7 wherein said R.F. transmitter unit and signal sensitive means for said tire is mounted on the vehicle adjacent the tire.