SELF-POWERED SENSOR SYSTEM FOR MONITORING TIRE PRESSURE

• US 20100164705A1
• Filed: 12/24/2009
• Published: 07/01/2010
• Est. Priority Date: 12/31/2008
• Status: Active Grant

• Current Assignee: STMicroelectronics Incorporated (STMicroelectronics NV)
• Original Assignee: STMicroelectronics Incorporated (STMicroelectronics NV)
• Inventors: Blanchard, Richard Austin
• Granted Patent: US 8,742,912 B2
• Time in Patent Office: Days
• US Class Current: 340/442
• CPC Class Codes: B60C 23/041 Means for supplying power to the signal- transmitting means on the wheel
• CPC Class Codes: B60C 23/0411 Piezoelectric generators
• CPC Class Codes: B60C 23/0413 Wireless charging of active radio frequency circuits
• CPC Class Codes: B60C 23/0491 Constructional details of means for attaching the control device

Abstract

A self-powered tire pressure sensor device. The sensor device includes a power circuit, an air pressure measurement sensor, a signal circuit and a wireless transmission circuit. The power circuit converts mechanical acceleration experienced by the device into electrical potential using an electromechanical transducer. Mechanical acceleration due to collisions between the mobile sensor device and the wall of the tire while the tire is in motion cause the transducer to emit a small electrical charge. An electrical potential storage element in the power circuit accumulates and stores the charge as electrical potential. Alternatively the power circuit receives and converts electromagnetic energy into electrical potential. The electrical potential powers an air pressure measurement sensor within the tire. A signal circuit and wireless transmission circuit transmit the measurement to a chassis-mounted receiver, which makes the tire pressure measurement available to systems remote from the tire.

Claims

1. A tire pressure sensor system comprising:

an air pressure measurement sensor located inside an inflatable portion of a tire;

a power circuit coupled to the air pressure measurement sensor and configured to drive the measurement sensor;

a signal circuit coupled to the air pressure measurement sensor and configured to process a measurement signal received from the air pressure measurement sensor; and

a wireless transmission circuit coupled to the signal circuit and configured to wirelessly transmit the measurement signal to a wireless receiver remotely located from the measurement sensor.

2. The system of claim 1 wherein the power circuit includes an electromechanical transducer configured to convert mechanical acceleration experienced by the power circuit into electrical potential.

3. The system of claim 2 wherein the power circuit further includes an electrical potential storage element configured to store the electrical potential converted by the power circuit.

4. The system of claim 1, further comprising a wireless receiver, wherein the power circuit is coupled to the wireless receiver and configured to convert electromagnetic energy received by the wireless receiver into electrical potential.

5. The system of claim 4 wherein the wireless transmission circuit and the wireless transceiver are integrated into a common circuit.

6. The system of claim 1 wherein the air pressure measurement sensor is a piezoresistive air pressure measurement sensor.

7. A system for measuring air pressure in an inflatable automobile tire comprising:

an inflatable tire mounted on a wheel and rotatable about a hub of an automobile;

an air pressure measurement sensor located within an inflatable portion of the mounted tire;

an electromechanical transducer coupled to the air pressure measurement sensor by a power circuit and configured to power the air pressure sensor by electrical potential converted from mechanical acceleration experienced by the electromechanical transducer;

a wireless transmission circuit coupled to the air pressure measurement sensor by a signal circuit and configured to wirelessly transmit an air pressure measurement signal received from the sensor;

a wireless receiver located on a chassis of the automobile and configured to receive the air pressure measurement signal from the wireless transmission circuit; and

an output interface coupled to the wireless receiver and configured to output an air pressure measurement value.

8. The system of claim 7 wherein the air pressure measurement sensor, the electromechanical transducer and the wireless transmission circuit are an integrated device.

9. The system of claim 8, further comprising a plurality of the integrated device, each in wireless communication with the wireless receiver.

10. The system of claim 8, further comprising a processor communicatively coupled with the base transceiver and the interface and configured to execute a statistical calculation on a plurality of remotely measured air pressure measurement values.

11. The system of claim 10 wherein the statistical calculation includes calculation of at least one of an average value and a standard deviation value of the plurality of received air pressure measurement values.

12. A method for remotely sensing air pressure in an inflatable tire comprising:

converting in a power circuit inside a tire energy from a first source into electrical energy;

driving an air pressure measurement sensor electrically connected to the power circuit using the converted electrical energy;

measuring the air pressure inside the tire using the air pressure measurement sensor; and

wirelessly transmitting from a remote transceiver electrically connected to the air pressure measurement sensor to a base transceiver outside the tire a signal encoded with a value corresponding to the measured air pressure.

13. The method of claim 12 further comprising wirelessly transmitting electromagnetic energy from the base transceiver to the remote transceiver inside the tire.

14. The method of claim 12 wherein said step of converting in a power circuit inside a tire energy from a first source into electrical energy includes:

converting mechanical energy based on movement of the tire into electrical energy.

15. The method of claim 12 further comprising storing the converted electrical energy in an electrical energy storage element.

16. The method of claim 15 further comprising accumulating the converted electrical energy over a duration of time.

17. The method of claim 12 further comprising outputting the measured air pressure value to a communicatively coupled output interface.