TIRE PRESSURE MONITORING DEVICE

• US 20070159315A1
• Filed: 03/20/2007
• Published: 07/12/2007
• Est. Priority Date: 10/01/2004
• Status: Active Grant

• Current Assignee: Murata Manufacturing Co Limited
• Original Assignee: Murata Manufacturing Co Limited
• Inventors: Murata, Tsuneo, Yamagata, Yuki
• Granted Patent: US 8,013,725 B2
• Time in Patent Office: Days
• US Class Current: 340/447
• CPC Class Codes: B60C 23/0416 allocating a corresponding wheel position on vehicle, e.g. front/left or rear/right
• CPC Class Codes: B60C 23/0444 Antenna structures, control or arrangements thereof, e.g. for directional antennas, diversity antenna, antenna multiplexing or antennas integrated in fenders

Abstract

Pneumatic pressure monitoring units that measure pneumatic pressures of respective tires and that transmit results of the measurements of the pneumatic pressures from respective antennas by the use of radio signals are provided at the tires, respectively. A communication unit including a beam controller arranged to selectively direct reception beams towards the respective tires is provided at substantially the center near the bottom surface of a vehicle. The antennas of the respective pneumatic pressure monitoring units are constructed so that directivity patterns of transmission beams are directed towards the inside in axle directions of the tires.

Claims

1. A tire pressure monitoring device comprising:

pneumatic pressure monitoring units that are disposed at respective tires of a vehicle, that measure pneumatic pressures of the tires, and that transmit results of the measurements of the pneumatic pressures from antennas using radio signals; and

a communication unit that receives the radio signals from the pneumatic pressure monitoring units;

wherein

the communication unit is disposed in the vehicle, and is provided with a beam controller arranged to selectively direct reception beams in directions of the respective tires.

2. The tire pressure monitoring device according to claim 1, wherein, after selectively directing a transmission beam towards one of the tires and transmitting a signal to the pneumatic pressure monitoring unit of the tire, the communication unit receives a signal that is transmitted from the pneumatic pressure monitoring unit of the tire.

3. The tire pressure monitoring device according to claim 1, wherein the antennas of the pneumatic pressure monitoring units are directional antennas whose directivities are towards an inside in axle directions of the tires.

4. The tire pressure monitoring device according to claim 1, wherein each pneumatic pressure monitoring unit includes a unit arranged to convert an electromagnetic wave into electrical power.

5. The tire pressure monitoring device according to claim 4, wherein the unit for converting an electromagnetic wave into electrical power of each pneumatic pressure monitoring unit converts a transmission signal transmitted from the communication unit into electrical power.

6. The tire pressure monitoring device according to claim 1, wherein the communication unit includes a beam controller arranged to selectively direct the reception beams towards the respective tires and provided at substantially a center near a bottom surface of the vehicle.

7. The tire pressure monitoring device according to claim 1, wherein the antenna includes a monopole power-supplying element disposed at a central portion of a grounded disc-shaped ground conductor, and four monopole non-power-supplying elements disposed around the power-supplying element.

8. The tire pressure monitoring device according to claim 7, wherein the disc-shaped ground conductor includes a disc-shaped portion and a cylindrical portion extending downward from a periphery of the disc-shaped ground conductor.

9. The tire pressure monitoring device according to claim 8, wherein the antenna further includes a power supply circuit disposed in an interior of the cylindrical portion and connected to the power-supplying element.

10. The tire pressure monitoring device according to claim 7, wherein the antenna further includes variable reactance circuited respectively disposed between the four non-power-supplying elements and ground.

11. The tire pressure monitoring device according to claim 1, wherein each of the pneumatic pressure monitoring units includes a pressure sensor that detects the pneumatic pressure of a respective one of the tires, and a control circuit that measures the pneumatic pressure.

12. The tire pressure monitoring device according to claim 11, wherein the pneumatic pressure monitoring units further include an RF transmission circuit that encodes a result of the measurement by the control circuit and transmits the result by radio to the antenna.