Tire condition monitoring system

• US 20030234722A1
• Filed: 06/20/2002
• Published: 12/25/2003
• Est. Priority Date: 12/20/1999
• Status: Active Grant

• Current Assignee: ANTHONY LONSDALE & BRYAN LONSDALE
• Original Assignee: ANTHONY LONSDALE & BRYAN LONSDALE
• Inventors: Vile, David, Freakes, Graham, Beckley, John, Lonsdale, Anthony, Lonsdale, Bryan
• Granted Patent: US 7,034,661 B2
• Time in Patent Office: Days
• US Class Current: 340/445
• 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 23/0428 using passive wheel mounted resonance circuits
• CPC Class Codes: B60C 23/0433 Radio signals
• CPC Class Codes: B60C 23/0449 Passive transducers, e.g. using surface acoustic waves, backscatter technology or pressure sensitive resonators near field passive transducers B60C23/0428
• CPC Class Codes: B60C 23/0483 Wireless routers between wheel mounted transmitters and chassis mounted receivers

Abstract

A monitoring system, particularly suitable for monitoring conditions (e.g. pressure or temperature) of a vehicle tire comprises a passive sensor (102, 104), an antenna (106) associated with said passive sensor, and switching means (108) for controlling the connection between the passive sensor and the antenna such that, in a first state of said switching means, said antenna is prevented from transmitting a signal generated by the passive sensor, and, in a second state of said switching means, said antenna is permitted to transmit a signal generated by the passive sensor. The switching means is operated remotely by means of a control signal. The control signal may be derived from the sum or difference of RF signals (F₁ and F₂) applied to a filter (112) In alternative embodiments the control signal is the modulating frequency of an AM or FM modulated radio signal or a radio signal carrying a digital code.

Claims

1. Apparatus comprising:

a passive sensor;

an antenna associated with said passive sensor;

switching means for controlling the connection between the passive sensor and the antenna such that, in a first state of said switching means, said antenna is prevented from transmitting a signal generated by the passive sensor, and, in a second state of said switching means, said antenna is permitted to transmit a signal generated by the passive sensor; and

remotely operable control means for controlling the state of the switching means.

7. Apparatus according to any preceding claim comprising means for generating a voltage in response to receiving a switching signal.

8. Apparatus according to claim 7 wherein the voltage generating means is powered by said switching signal itself.

9. Apparatus according to claim 7 wherein the voltage generating means comprises means for generating electrical energy in response to movement of the tyre.

10. Apparatus according to claim 8 or claim 9 comprising a virtual battery.

11. Apparatus according to any preceding claim wherein the switching means comprises a Field-Effect Transistor and/or an amplifier.

2. Apparatus according to claim I wherein the switching means is controlled by a coded radio frequency control signal.

3. Apparatus according to claim 2 comprising a mixer for mixing two rf signals and a band pass filter connected to the output of the mixer, the band pass filter being effective to change the switching means to the second state if the output from the mixer corresponds to the pass frequency of the filter.

4. Apparatus according to claim 3 wherein the rf signals are in the 2.45 GHz band.

5. Apparatus according to claim 2 comprising a detector circuit for detecting the modulation frequency of a frequency modulated or amplitude modulated rf signal and a band pass filter connected to the output of the detector, the band pass filter being effective to change the switching means to the second state if the output from the detector corresponds to the pass frequency of the filter

6. Apparatus according to claim 2 comprising a digital filter for changing the switching means to the second state if a digital code carried by the rf signal corresponds to the digital code of the digital filter.

12. A method of interrogating a passive sensor via an antenna associated with said passive sensor, the method comprising the steps of generating a predetermined switching signal;

and applying said switching signal to switching means so as to control the connection between the passive sensor and the antenna.

13. A tyre condition monitoring device comprising:

one or more sensors for sensing a condition of a tyre;

storage means for storing an identification code associated with the sensor;

receiving means for receiving a signal from a remote interrogating device, the signal including a portion indicative of an identification code;

means of comparing the identification code received by the receiving means with the identification code stored in the storage means;

a switch for connecting the sensor to the receiving means in response to an indication from the comparator that the identification code of the received signal corresponds to the identification code stored in the storage means; and

a power supply for supplying electrical power to the device.

14. A tyre condition monitoring device according to claim 13 wherein the power supply may include means for generating electrical energy within the tyre as the tyre is used and means for storing the electrical energy so generated.

15. A tyre condition monitoring device according to claim 13 wherein the power supply means comprises means for capturing radio frequency (rf) energy received from the exterior of the tyre.

16. A tyre condition monitoring device according to any of claims 13 to 15 wherein the means for generating electrical energy generates a pre-determined number of pulses of electrical energy, for example one pulse of electrical energy, per revolution of the tyre.

17. A tyre condition monitoring device according to the device for producing a pulse of electrical energy is a piezo electric device, for example a PVDF device embedded within the structure of the tyre.

18. A tyre condition monitoring device comprising:

one or more sensors for sensing a condition of a tyre;

storage means for storing an identification code associated with the sensor;

receiving means for receiving a signal from a remote interrogating device, means for sending to the interrogation device signals indicative of the condition to which the sensor is sensitive, means for sending to the interrogation device signals indicative of the identification code, and a power supply for supplying electrical power to the device.