Method and apparatus for detecting wheel motion in a tyre pressure monitoring system

• US 20050081615A1
• Filed: 09/08/2004
• Published: 04/21/2005
• Est. Priority Date: 09/10/2003
• Status: Active Grant

• Current Assignee: Schrader Electronics Limited (Sensata Technologies Holding Plc)
• Original Assignee: Schrader Electronics Limited (Sensata Technologies Holding Plc)
• Inventors: McCall, Alan Kenneth, Strahan, Samuel Kane, Stewart, William David
• Granted Patent: US 7,104,123 B2
• Time in Patent Office: Days
• US Class Current: 73/146
• CPC Class Codes: B60C 23/0408 transmitting the signals by non-mechanical means from the wheel or tyre to a vehicle body mounted receiver

Abstract

An apparatus for detecting motion of a wheel comprising tyre. The apparatus comprises a pressure sensor for measuring the tyre pressure and generating a signal corresponding to the measured tyre pressure, and means for detecting a component of said signal that corresponds to, or is generated by, vibrations of the tyre. Upon detection of the signal component, the apparatus determines that the wheel is in motion. The detecting means may arranged to detect an audio signal component or signal components having a frequency in the range 200 Hz to 300 Hz.

Claims

1. An apparatus for detecting motion of a wheel comprising a tyre, the apparatus comprising a pressure sensor arranged to measure the tyre pressure and to generate a signal corresponding to the measured tyre pressure;

and means for detecting a component of said signal that corresponds to vibrations of the tyre, wherein, upon detection of said signal component, the apparatus determines that the wheel is in motion.

2. An apparatus as claimed on claim 1, wherein said detecting means is arranged to detect an audio signal component.

3. An apparatus as claimed in claim 1, wherein said signal component has a frequency in the range 200 Hz to 300 Hz.

4. An apparatus as claimed in claim 1, wherein the pressure sensor-generates an analogue signal, the apparatus comprising an analogue-to-digital converter (ADC) arranged to receive the analogue signal and to produce a corresponding digital signal, the detecting means being arranged to detect said signal component in said corresponding digital signal.

5. An apparatus as claimed in claim 4, wherein the detecting means is arranged to detect said signal component in one or more of the least significant bits of the ADC signal.

6. An apparatus as claimed in claim 1, in which the pressure sensor generates an analogue signal, the apparatus comprising a filter arranged to filter the sensor signal in order to extract said signal component;

and a comparator arranged to compare the filtered sensor signal with a reference signal and to generate a comparator signal, the detecting means being arranged to detect said signal component from the characteristics of the comparator signal.

7. An apparatus as claimed in claim 6, in which the detecting means is arranged to detect pulses in said comparator signal.

8. An apparatus as claimed in claim 7, wherein the detecting means determines that said signal component is present by detecting a train of two or more pulses in said comparator signal.

9. A tyre pressure monitoring device comprising the apparatus of claim 1.

10. A method of detecting motion of a wheel comprising a tyre, the method comprising measuring the tyre pressure;

generating a signal corresponding to the measured tyre pressure;

detecting a signal component of said signal that corresponds to vibrations of the tyre; and

, upon detection of said signal component, determining that the wheel is in motion.

11. A method as claimed in claim 10, wherein said signal component detection involves detecting an audio signal component.

12. A method as claimed in claim 10, wherein said signal component detection involves detecting a signal component having a frequency in the range 200 Hz to 300 Hz.

13. A computer program product comprising computer program code for causing a computer to perform the method of claim 10.