Tyre condition monitoring system

• US 6,271,748 B1
• Filed: 10/20/1997
• Issued: 08/07/2001
• Est. Priority Date: 08/31/1994
• Status: Expired due to Fees

• Current Assignee: Andrew John Derbyshire, Edward Charles Gibson, Jeremy Francis Siddons, John Kitto Richards, Sean Patrick Davies
• Original Assignee: Andrew John Derbyshire, Edward Charles Gibson, Jeremy Francis Siddons, John Kitto Richards, Sean Patrick Davies
• Inventors: Siddons, Jeremy Francis, Gibson, Edward Charles, Derbyshire, Andrew John, Richards, John Kitto, Davies, Sean Patrick
• Primary Examiner(s): Wu, Daniel J.
• Assistant Examiner(s): TWEEL JR, JOHN ALEXANDER
• Application Number:
  US08/793,586
• Time in Patent Office: 1,387 Days
• Field of Search: 340/442, 340/447, 340/445, 340/444, 73/146.5, 73/146.3, 73/146.4, 200/61.22
• US Class Current: 340/442
• CPC Class Codes: B60C 23/0401 characterised by the type of alarm
• 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
• CPC Class Codes: B60C 23/0454 Means for changing operation mode, e.g. sleep mode, factory mode or energy save mode
• CPC Class Codes: B60C 23/0457 self triggered by timer
• CPC Class Codes: B60C 23/0459 self triggered by motion sensor
• CPC Class Codes: B60C 23/0462 Structure of transmission protocol
• CPC Class Codes: H04L 7/06 the synchronisation signals differing from the information signals in amplitude, polarity or frequency or length

Abstract

A tyre condition monitoring system comprises a wheel transmitter unit for each wheel of a vehicle. The transmitter unit is mountable in the wheel and has sensors for sensing pressure and temperature in and rotation of the wheel. Signals from the sensors are processed by a processor to produce data which is transmitted via a radio frequency transmitter. The data is transmitted with the data representing a unit identity code. Transmitted data is received by a receiver unit where it is analyzed to determine the condition of the tyre. The receiver unit includes a user operable input for setting threshold limits for the temperature and/or pressure such that if a threshold is passed an alarm is sounded. Each wheel transmitter unit includes a power supply and is arranged so that power is only applied during the sensing and transmission of data. Intervals between transmissions of data can be varied depending on whether rotation of the wheel has been sensed.

Claims

1. A tyre condition monitoring system, comprising:

at least one wheel transceiver unit mountable in a wheel of a vehicle; and

a central transceiver unit for transmitting commands to the at least one wheel transceiver unit and receiving tyre condition data transmitted in reply to said commands from said wheel transceiver unit, wherein the transmission of each command is preceded by a preamble and wherein the preamble comprises a plurality of preamble periods in which time information is transmitted relating to the time until the command will be transmitted and the wheel transceiver unit is arranged to respond to said time information by powering down depending on the time remaining until transmission of the command.

2. A tyre condition monitoring system as claimed in claim 1, wherein the central transceiver unit comprises a processor for determining commands to be transmitted and for processing received data.

3. A tyre condition monitoring system as claimed in claim 2, wherein the processor is arranged to monitor the received data for changes in the tyre condition and to vary the commands transmitted in dependence thereon.

4. A tyre condition monitoring system as claimed in claim 1, wherein the central transceiver unit comprises means for determining when the vehicle is in use and is operable in a first mode when the vehicle is in use to transmit commands frequently and in a second mode when the vehicle is not in use to transmit commands less frequently.

5. A tyre condition monitoring system as claimed in claim 1, wherein the time information is transmitted in the form of a digital signal having a frequency related to the remaining time.

6. A tyre condition monitoring system as claimed in claim 1, wherein the central transceiver unit is operable to transmit data to the wheel transceiver unit.

7. A tyre condition monitoring system as claimed in claim 6, wherein the data from the central transceiver unit comprises identity data uniquely identifying the wheel transceiver unit which is transmittable during installation of the system.

8. A tyre condition monitoring system as claimed in claim 7, wherein the commands transmittable from the central transceiver unit comprise a command to transmit the identity data.

9. A tyre condition monitoring system as claimed in claim 1, wherein the commands transmittable from the central transceiver unit comprise a command to the wheel transceiver unit to store calibration data.

10. A tyre condition monitoring system as claimed in claim 1, wherein the commands transmittable from the central transceiver unit comprise a command to transmit data pertaining to the condition of the tyre.

11. A tyre condition monitoring system as claimed in claim 9, wherein the commands transmittable from the central transceiver unit comprise a command to transmit stored calibration data.

12. A tyre condition monitoring system as claimed in claim 1, comprising a plurality of wheel transceiver units and wherein the central transceiver unit is operable to transmit commands individually to each wheel transceiver unit or globally to all wheel transceiver units.

23. A tyre condition monitoring system as claimed in claim 1, wherein the wheel transceiver unit comprises a transceiver circuit, said transceiver circuit including, an oscillator circuit for providing a reference frequency signal, a modulating circuit for modulating a data signal representing data to be transmitted with the reference signal and outputting the modulated signal for transmission, a receiver circuit for receiving a modulated data signal which receiver circuit is arranged to receive also signals from the modulating circuit derived from the reference signal, and a demodulating circuit for demodulating the received signal to extract the data therefrom.

24. A tyre condition monitoring system as claimed in claim 1, wherein the central transceiver unit comprises a transceiver circuit, said transceiver circuit including, an oscillator circuit for providing a reference frequency signal, a modulating circuit for modulating a data signal representing data to be transmitted with the reference signal and outputting the modulated signal for transmission, a receiver circuit for receiving a modulated data signal which receiver circuit is arranged to receive also signals from the modulating circuit derived from the reference signal, and a demodulating circuit for demodulating the received signal to extract the data therefrom.

13. A transceiver circuit, comprising:

an oscillator circuit for providing a reference frequency signal, a modulating circuit for modulating a data signal representing data to be transmitted with the reference signal and outputting the modulated signal for transmission, a receiver circuit for receiving a modulated data signal which receiver circuit is arranged to receive also signals from the modulating circuit derived from the reference signal, and a demodulating circuit for demodulating the received signal to extract the data therefrom.

14. A transceiver circuit as claimed in claim 13, wherein the oscillator circuit comprises a surface acoustic wave resonator.

15. A transceiver circuit as claimed in claim 13, wherein the modulator circuit comprises a voltage controlled oscillator.

16. A transceiver circuit as claimed in claim 15, wherein the voltage controlled oscillator is arranged to provide a signal which is applied as an in-phase and a quadrature signal to the receiver circuit.

17. A transceiver circuit as claimed in claim 13, wherein the oscillator circuit comprises a frequency synthesizer driven by a crystal.

18. A transceiver circuit as claimed in claim 17, wherein the modulator circuit comprises a voltage controlled oscillator, and a mixer connected to the voltage controlled oscillator and to receive a signal representing data to be transmitted.

19. A transceiver circuit as claimed in claim 18, wherein the signal representing data to be transmitted is generated by a frequency shift keying modulator circuit.

20. A transceiver circuit as claimed in claim 13, wherein the receiver circuit comprises a low noise amplifier.

21. A transceiver circuit as claimed in claim 13, wherein the receiver circuit comprises a mixer connected to receive the signals from the modulating circuit.

22. A transceiver circuit as claimed in claim 13, wherein the receiver circuit comprises a low pass filter and threshold detector for conditioning received signals for input to the demodulating circuit.