VEHICLE TIRE PRESSURE MONITOR SYSTEM

• US 3,694,803 A
• Filed: 07/28/1971
• Issued: 09/26/1972
• Est. Priority Date: 07/28/1971
• Status: Expired due to Term

• Current Assignee: SP-Microwave, Inc.
• Original Assignee: Harry F. Strenglein
• Inventors: Strenglein, Harry F.
• Primary Examiner(s): Waring, Alvin H.
• Application Number:
  US05/166,892
• Time in Patent Office: 426 Days
• Field of Search: 340/58,224,227,227.1,229 325/111,117,118
• US Class Current: 340/447
• CPC Class Codes: B60C 23/0408 transmitting the signals by non-mechanical means from the wheel or tyre to a vehicle body mounted receiver
• CPC Class Codes: B60C 23/0433 Radio signals

Abstract

The condition monitor provides information as to the state of a monitored dual state device having, for example, possible satisfactory and unsatisfactory conditions. Use is made of a passive transducer element powered by a space-transmitted radio frequency signal of fundamental carrier frequency. In the unsatisfactory condition of the monitored device, the passive transducer emits a signal that is a harmonic of the carrier frequency, which signal is detected for the operation of a suitable alarm or remedial control. In the normal or satisfactory condition of the monitored device, the carrier frequency energy causes the passive transducer to inhibit production of second harmonic energy.

Claims

1. Apparatus for monitoring the condition of a device having first and second possible conditions comprising:

switch means having first and second states, sensor means responsive to said first or said second conditions of said device for placing said switch means in said first or in said second state, transducer means adapted to be excited by carrier frequency signal energy and comprising rectifier means, and circuit means including said switch means in series relation with said rectifier means for generating a signal at a harmonic of said carrier frequency when said switch is in said first state, and means coupled to said circuit means for radiating said harmonic signal.

2. Apparatus as described in claim 1 wherein said means for radiating said harmonic signal comprises antenna means adapted also to receive said carrier frequency signal.

3. Apparatus as described in claim 2 additionally including signal generator means for radiating carrier frequency signals for exciting said antenna means.

4. Apparatus as described in claim 2 additionally including receiver means for receiving said harmonic signal, said receiver means comprising:

second antenna means, receiver-detector means coupled to said second antenna means, and means for utilizing the output of said receiver-detector means.

5. Apparatus as described in claim 4 wherein said utilization means comprises alarm means.

6. Apparatus as described in claim 5 wherein said utilization means comprises actuator means for operating remedial control means.

7. Apparatus as described in claim 4 wherein said second antenna means is tuned substantially to the frequency of said harmonic signal.

8. Apparatus as described in claim 4 additionally including filter means for passing substantially said harmonic signal from said second antenna means to said receiver-detector means.

9. Apparatus as described in claim 1 wherein said sensor means comprises a pressure sensor.

10. Apparatus as described in claim 1 wherein said switch means, said sensor means, and said transducer means are mounted upon a movable element.

11. Apparatus as described in claim 10 wherein said movable element comprises a wheel rotatable about an axis.

12. Apparatus as described in claim 11 wherein said switch means, said sensor means, and said transducer means are mounted within an interior region of said wheel.

13. Apparatus as described in claim 12 including window means comprising part of said wheel for permitting said transducer means to receive said carrier frequency signal energy and to transmit said harmonic signal.

14. Apparatus as described in claim 13 additionally including:

a pneumatic tire mounted upon said wheel, and gas conduction means for connecting the interior of said tire to said sensor.

15. Apparatus as described in claim 1 wherein said circuit means comprises in series connection with said rectifier means:

resistor means, and capacitive means, said capacitive means being coupled across said switch means, said resistor means and said rectifier means having a common junction, said common junction being adapted to be coupled to antenna means.

16. Apparatus as described in claim 15 wherein said circuit means comprises in series connection with said rectifier means:

first capacitive means, inductive means, and second capacitive means, said second capacitive means being coupled across said switch means, said first capacitive means and said inductive means having a common junction therebetween, said common junction being adapted to be coupled to antenna means.

17. Apparatus as described in claim 1 additionally comprising:

generator means for generating carrier frequEncy signal energy, modulation signal generator means, and modulator means for amplitude modulating said carrier frequency signal energy in response to said modulation signal generator means.

18. Apparatus as described in claim 17 additionally comprising:

receiver means for responding to said radiated harmonic signal for producing an output, gated detector means responsive to said modulator means for detecting said receiver means output, and means for utilizing the output of said gated detector means.

19. Apparatus for monitoring the condition of a device having first and second possible conditions comprising:

switch means having first and second states, sensor means responsive to said first or said second conditions of said device for placing said switch means in said first or in said second state, transducer means adapted to be excited by carrier frequency signal energy and comprising rectifier means, circuit means including said switch means in series relation with said rectifier means for modifying said carrier frequency signal energy when said switch is in said first state, and means coupled to said circuit means for radiating said modified carrier frequency signal energy.