Tire inflation pressure sensing apparatus supplied with electrical power via wireless communication

• US 20050258953A1
• Filed: 05/19/2005
• Published: 11/24/2005
• Est. Priority Date: 05/21/2004
• Status: Active Grant

• Current Assignee: DENSO Corporation, Nippon Soken, Inc.
• Original Assignee: DENSO Corporation, Nippon Soken, Inc.
• Inventors: Hanai, Yoshinori, Saitou, Takashi, Takaoka, Akira
• Granted Patent: US 7,271,710 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

Abstract

A tire inflation pressure sensing apparatus includes a transmitter provided on a wheel of a vehicle and a receiver provided on a body of the vehicle. The transmitter includes a pressure sensor working to generate a pressure signal and a charging unit configured to be charged with electrical power via a radio wave from the receiver. The transmitter is configured to be triggered to send out the pressure signal by a change of operation of the receiver from an ON-mode, in which the receiver sends out the radio wave, to an OFF-mode in which that stops sending out the radio wave. The receiver works to change the operation thereof alternately between the ON-mode and OFF-mode in accordance with predefined processes, so that reliable transmissions of both the radio wave and the pressure signal between the transmitter and receiver are ensured without determining the relative position of the transmitter and receiver.

Claims

1. A tire inflation pressure sensing apparatus comprising:

a pressure sensor provided on a wheel of a vehicle, said pressure sensor working to sense an inflation pressure of a tire mounted on the wheel and generate a pressure signal representative of the sensed inflation pressure of the tire;

a transmitter provided on the wheel of the vehicle, said transmitter including a first antenna and being configured to send out the pressure signal generated by said pressure sensor through the first antenna;

a receiver provided on a body of the vehicle, said receiver including a second antenna and being configured to send out through the second antenna a radio wave for electrical power charge toward said transmitter, receive through the second antenna the pressure signal from said transmitter, and determine the inflation pressure of the tire based on the received pressure signal, said receiver selectively operating in an ON-mode, in which said receiver sends out the radio wave, and an OFF-mode in which said receiver stops sending out the radio wave; and

a charging unit provided on the wheel of the vehicle, said charging unit being configured to be charged with an electrical power induced by the radio wave received by said transmitter through the first antenna, and supply the electrical power to said pressure sensor and said transmitter,

wherein said transmitter has a predetermined range of angular position with respect to said receiver, within which levels of the radio wave received by said transmitter and the pressure signal received by said receiver are above a necessary level for establishing a desired communication between said transmitter and said receiver; and

said transmitter is configured to be triggered to send out the pressure signal by a change of operation of said receiver from the ON-mode to the OFF-mode, and

wherein said receiver works to;

calculate a time Tt required for said transmitter to complete one turn;

calculate a time Ts required for said transmitter to pass through the predetermined range of angular position based on the time Tt;

calculate a difference T between the time Ts and a time Td required for said transmitter to complete sending out the pressure signal; and

change an operation thereof alternately between the ON-mode and OFF-mode during one complete turn of said transmitter together with the wheel such that a time interval between two continuous changes from the ON-mode to the OFF-mode is equal to or less than T.

2. The tire inflation pressure sensing apparatus as set forth in claim 1, wherein said receiver further works to calculate a time Tc required for completing the charge of the charging unit with electrical power when the wheel rotates based on the times Tt and Ts, and keep the operation thereof in the ON-mode for a time interval of Tc before changing the same alternately between the ON-mode and OFF-mode.

3. The tire inflation pressure sensing apparatus as set forth in claim 2, wherein the time Tc is determined by the following equation:

Tc=(Tcs/Ts)×

Tt,

where Tcs is a time required for completing the charge of the charging unit with electrical power when the wheel remains stationary.

4. The tire inflation pressure sensing apparatus as set forth in claim 1, wherein said receiver further works to accumulate the number of times changing the operation thereof from the ON-mode to the OFF-mode and stop changing the operation alternately between the ON-mode and OFF-mode when the accumulated number becomes no less than Tt/T.

5. A tire inflation pressure sensing apparatus comprising:

a pressure sensor provided on a wheel of a vehicle, said pressure sensor working to sense an inflation pressure of a tire mounted on the wheel and generate a pressure signal representative of the sensed inflation pressure of the tire;

a transmitter provided on the wheel of the vehicle, said transmitter including a first antenna and being configured to send out the pressure signal generated by said pressure sensor through the first antenna;

a receiver provided on a body of the vehicle, said receiver including a second antenna and being configured to send out through the second antenna a radio wave for electrical power charge toward said transmitter, receive through the second antenna the pressure signal from said transmitter, and determine the inflation pressure of the tire based on the received pressure signal, said receiver selectively operating in an ON-mode, in which said receiver sends out the radio wave, and an OFF-mode in which said receiver stops sending out the radio wave; and

a charging unit provided on the wheel of the vehicle, said charging unit being configured to be charged with an electrical power induced by the radio wave received by said transmitter through the first antenna, and supply the electrical power to said pressure sensor and said transmitter,

wherein said transmitter has a predetermined range of angular position with respect to said receiver, within which levels of the radio wave received by said transmitter and the pressure signal received by said receiver are above a necessary level for establishing a desired communication between said transmitter and said receiver; and

said transmitter is configured to be triggered to send out the pressure signal by a change of operation of said receiver from the ON-mode to the OFF-mode, and

wherein said receiver works to;

calculate a time Tt required for said transmitter to complete one turn;

calculate a time Ts required for said transmitter to pass through the predetermined range of angular position based on the time Tt;

calculate a difference T between the time Ts and a time Td required for said transmitter to complete sending out the pressure signal; and

change an operation thereof alternately between the ON-mode and OFF-mode so as to keep the operation in the ON-mode for a time interval of (N×

Tt), where N is a given integer, and in the OFF-mode for a time interval of T or less.

6. The tire inflation pressure sensing apparatus as set forth in claim 5, wherein the integer N is such that (N×

Tt) is equal or most approximate to a time Tc required for completing the charge of the charging unit with electrical power when the wheel rotates.

7. The tire inflation pressure sensing apparatus as set forth in claim 6, wherein the time Tc is determined by the following equation:

Tc=(Tcs/Ts)×

Tt,

where Tcs is a time required for completing the charge of the charging unit with electrical power when the wheel remains stationary.

8. The tire inflation pressure sensing apparatus as set forth in claim 5, wherein said receiver further works to accumulate the number of times changing the operation thereof from the ON-mode to the OFF-mode and stop changing the operation alternately between the ON-mode and OFF-mode when the accumulated number becomes no less than Tt/T.