Device for monitoring and wirelessly indicating a pressure or a pressure change in pneumatic tires mounted on vehicles

• US 20060273889A1
• Filed: 05/19/2004
• Published: 12/07/2006
• Est. Priority Date: 05/20/2003
• Status: Active Grant

• Current Assignee: Huf Baolong Electronics Bretten GmbH (Huf Hulsbeck & Furst GmbH & Co. KG)
• Original Assignee: Beru Aktiengesellschaft (BorgWarner Incorporated)
• Inventors: Frank, Michael, Schulze, Gunter
• Granted Patent: US 7,464,587 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 23/041 Means for supplying power to the signal- transmitting means on the wheel

Abstract

A device for monitoring and wirelessly signaling a pressure, or a change in pressure, in pneumatic tires on vehicles having a pressure sensor for measuring the pressure or the change in pressure; a transmitter for transmitting a signal derived from the measuring signal of the pressure sensor; a control circuit that activates the transmitter only from time to time; a battery (1) as current source; and a back-up capacitor connected in parallel to the battery. A controllable switching unit is provided by means of which the back-up capacitor can be connected in parallel to the battery from time to time for a limited period of time only.

Claims

1. Device for monitoring and wirelessly signaling a pressure, or a change in pressure, in pneumatic tires on vehicles comprising:

a pressure sensor for measuring the pressure or the change in pressure;

a transmitter for transmitting a signal derived from the measuring signal of the pressure sensor;

a control circuit that activates the transmitter only from time to time;

a battery as current source;

and a back-up capacitor connected in parallel to the battery; and

a controllable switching unit is provided by means of which the back-up capacitor can be connected in parallel to the battery from time to time for a limited period of time only.

2. The device as defined in claim 1, wherein the controllable switching unit has an input for control signals arriving from the control circuit by which the back-up capacitor can be brought into circuit from time to time for a limited period of time only.

3. The device as defined in claim 1, wherein the control circuit (4) is designed in such a way as to bring the back-up capacitor into circuit shortly before it activates the transmitter.

4. The device as defined in claim 3, wherein the control circuit is designed in such a way that it will activate the back-up capacitor every time shortly before it activates the transmitter.

5. The device as defined in claim 3, wherein the control circuit is designed in such a way that it will activate the back-up capacitor not every time the transmitter is activated, but only if and when necessary.

6. The device as defined in claim 5, wherein the control circuit comprises a comparator.

7. The device as defined in claim 6, wherein the control circuit is connected to a device for measuring the voltage of the battery and is designed in such a way that it will determine that the need exists when the voltage of the battery has dropped below a given limit value.

8. The device as defined in claim 7, wherein the control circuit determines that the need exists when the voltage of the battery has been determined to be below its limit value in one or more preceding activations of the transmitter.

9. The device as defined in claim 6, wherein the control circuit is connected to a sensor (8) and is designed in such a way that it will determine that the need exists when the measured value supplied by the sensor (8) is below or above a given limit value.

10. The device as defined in claim 9, wherein the measured value is the temperature.

11. The device as defined in claim 6, the control circuit is connected to a timer and is designed in such a way that it will determine that the need exists when a predetermined period of time has lapsed from the time the timer has been started.

12. The device as defined in claim 6, wherein the control circuit is connected to a counter (11), which continuously counts the number of the transmitting operations, and that the control circuit is designed in such a way that it will determine that the need exists when a predetermined number of transmitting operations has been exceeded.

13. The device as defined in claim 6, wherein the control circuit is designed in such a way that it will determine that the need exists when the pressure measured is determined to be below a given limit value.

14. The device as defined in claim 6, that wherein the control circuit is designed in such a way that it will determine that the need exists when the variation in pressure over time exceeds a given limit value.

15. The device as defined in claim 5, wherein the transmitter is coupled back to the control circuit and that the control circuit is designed in such a way that it evaluates a signal transmitted from the sensor through the feedback system to determine any information indicating that an attempted transmission has failed and that the control circuit determines that a need exists to bring the back-up capacitor into circuit by determining that an attempted transmission has failed.

16. The device as defined in claim 5, wherein the control circuit is designed in such a way that when a corresponding need has been determined to exist it will bring the back-up capacitor into circuit for a given number of transmitting operations and will then once more check the criterion or criteria that led to the determination that a corresponding need exists.

17. The device as defined in any claim 1, wherein the switching unit comprises a current limiter through which the back-up capacitor is charged, but not discharged.

18. The device as defined in claim 17, wherein the switching unit comprises two switching elements controlled by the control circuit the first of which serves to cut in the back-up capacitor via the current limiter, while the second serves to bridge the current limiter.

19. The device as defined in claim 1, wherein the switching unit comprises as switching elements a field effect transistor.

20. The device as defined in claim 2, wherein the control circuit is designed in such a way as to bring the back-up capacitor into circuit shortly before it activates the transmitter.