Tire pressure monitoring system

• US 20050242939A1
• Filed: 04/29/2005
• Published: 11/03/2005
• Est. Priority Date: 04/30/2004
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments Deutschland Gesellschaft Mit Beschrã¤Nkter Haftung (Texas Instruments, Inc.)
• Inventors: Meier, Herbert, Hagl, Andreas
• Granted Patent: US 7,378,951 B2
• Time in Patent Office: Days
• US Class Current: 340/447
• 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 23/0413 Wireless charging of active radio frequency circuits
• CPC Class Codes: B60C 23/0442 the transmitted signal comprises further information, e.g. instruction codes, sensor characteristics or identification data

Abstract

A vehicular tire pressure monitoring system, including a transponder unit (10) for each tire to be monitored, the transponder unit having an incorporated RF transmitter (12) and being physically associated with the tire to be monitored. A pressure sensor for each tire to be monitored is connected to circuitry in a corresponding transponder unit. An interrogator unit (7) is associated with each transponder unit and physically mounted on a vehicle in proximity to a wheel (9) whereon a tire to be monitored is mounted. A central RF receiver (4) for all transponder units is provided. Each transponder unit is inductively coupled with an associated interrogator unit and includes an electric charge accumulation element adapted to be charged by energy inductively supplied from the associated interrogator unit in a first mode of operation, and the charge accumulation element providing a power supply to the RF transmitter of the transponder unit in a second mode of operation.

Claims

1. A vehicular tire pressure monitoring system comprising:

a transponder unit for each tire to be monitored, the transponder unit having an incorporated RF transmitter and being physically associated with the wheel/tire to be monitored;

a pressure sensor for each tire to be monitored and connected to circuitry in a corresponding transponder unit;

an interrogator unit associated with each transponder unit and physically mounted on a vehicle in proximity to a wheel whereon a tire to be monitored is mounted; and

a central RF receiver for all transponder units;

wherein

each transponder unit is inductively coupled with an associated interrogator unit and includes an electric charge accumulation element adapted to be charged by energy inductively supplied from the associated interrogator unit in a first mode of operation, and the charge accumulation element providing a power supply to the RF transmitter of the transponder unit in a second mode of operation.

2. The monitoring system according to claim 1, wherein the electric charge accumulation element is a capacitor.

3. The monitoring system according to claim 1, wherein the central RF receiver is one installed in the vehicle as part of a remote control system and connected to a remote control controller provided with added functionality for processing data received from the transponder units and for driving a display device in the vehicle.

4. The monitoring system according to claim 3, wherein the interrogator units are also connected to, and controlled by, the remote control controller.

5. The monitoring system according to claim 3, wherein the remote control system is a remote keyless entry system.

6. The monitoring system according to claim 1, wherein the interrogator units are mounted in respective wheel housings of the vehicle and the charge accumulation elements are charged during rotation of respective wheels.

7. The monitoring system according to claim 6, wherein the interrogator units are mounted on a liner of plastics material and include an antenna that extends along a major part of the peripheral extension of the liner with respect to vehicle rotation.

8. The monitoring system according to claim 1, wherein the energy transmitted from the interrogator units to the transponder units is an electromagnetic wave at a carrier frequency in the LF range.

9. The monitoring system according to claim 2, wherein the capacitor has a capacity in a range of several pF to several tens of pF.

10. The monitoring system according to claim 1, wherein each transponder unit includes

a) an integrated circuit with

a programmable control unit,

a rectifier connected to LF input terminals and having an output,

a power terminal connected to the output of the rectifier,

at least one analog input terminal for a pressure sensor, and

an encoder with an input connected to an output of the programmable control unit and an output connected to an output terminal of the integrated circuit;

b) a resonant circuit with an inductor antenna and a capacitor, connected to the LF input terminals of the integrated circuit;

c) a charge accumulation capacitor connected to the power terminal of the integrated circuit; and

d) an RF transmitter with a signal input coupled to the output terminal of the integrated circuit, a supply input connected to the charge accumulation capacitor and an output connected to an antenna.