Wireless pressure sensing Schrader valve

• US 7,328,609 B1
• Filed: 10/29/2004
• Issued: 02/12/2008
• Est. Priority Date: 10/29/2004
• Status: Active Grant

• Current Assignee: National Semiconductor Corporation (Texas Instruments, Inc.)
• Original Assignee: National Semiconductor Corporation (Texas Instruments, Inc.)
• Inventors: Hopper, Peter J., Hwang, Kyuwoon, Drury, Robert, Mian, Michael
• Primary Examiner(s): Allen; Andre J.
• Application Number:
  US10/977,168
• Time in Patent Office: 1,201 Days
• Field of Search: 731/46, 731/468, 73/162
• US Class Current: 73/146.8
• 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 23/0496 Valve stem attachments positioned outside of the tyre chamber

Abstract

A wireless tire pressure sensing system based upon a Schrader valve design is provided. The system includes a valve body, a valve pin and a compression element for sealing engaging the valve body and the valve pin to maintain tire pressure. A pressure sensing device mounted within the valve body and connected to valve pin senses the pressure within the tire and provides its signal to the valve pin. The valve pin is adapted as a component of an antenna that transmits a wireless pressure signal to a remote receiver/transmitter mounted on the vehicle. The receiver/transmitter transmits a corresponding signal to a vehicle control system that generates a warning signal when the tire pressure is below a threshold safety value.

Claims

1. A wireless tire pressure sensing system comprising:

a tire valve body adapted for sealing engagement with a tire and for air flow communication with the interior cavity defined by the tire;

a valve pin mounted within the tire valve body, the valve pin being adapted for sealing engagement with the tire valve body when a preselected force is applied to the valve pin;

a compression element mounted within the tire valve body, the compression element being in contact with the valve pin to urge the valve pin into sealing engagement with the valve body to maintain a pressure within the interior cavity of the tire;

at least one enclosed cavity pressure sensing device mounted within the valve body for generating an output electrical pressure signal that corresponds to the pressure within the interior cavity of the tire, the pressure sensing device being connected to the valve pin to provide the output electrical pressure signal thereto, the pressure sensing device including

(i) driver circuitry;

(ii) a conductive lower capacitor plate formed at an upper surface of a semiconductor substrate, the lower capacitive plate being conductively coupled to the driver circuitry;

(iii) a conductive pad formed at the upper surface of the semiconductor substrate and spaced-apart from the lower capacitor plate, the conductive pad being conductively coupled to the driver circuitry;

(iv) patterned dielectric material formed over the upper surface of the semiconductor substrate and having a first opening formed therein to expose an upper surface of the conductive pad and having a second opening formed therein over the lower capacitor plate;

(v) a supporting layer of dielectric material formed on the patterned dielectric material, the supporting layer having a first opening formed therein over the conductive pad and having a plurality of opening formed therein over the second opening in the patterned dielectric material; and

(vi) an upper layer of conductive material formed on the supporting layer and extending through the first opening in the supporting layer and into the first opening in the patterned dielectric material to form electrical contact with the exposed upper surface of the conductive pad, the upper layer of conductive material extending over the plurality of opening formed in the supporting layer to close said openings to define an enclosed cavity between the lower capacitor plate and the upper conductive layer,

and wherein the valve pin comprises an antenna adapted to transmit a wireless pressure signal that corresponds to the pressure within the interior cavity of the tire.

2. A wireless tire pressure sensing system as in claim 1, and further comprising:

at least one leaky cavity pressure device formed on the semiconductor substrate and adapted for developing a tire cavity reference pressure signal;

differential circuitry formed on the semiconductor substrate and coupled to compare the electrical pressure signal from the at least one enclosed cavity pressure sensing device and the reference pressure signal at least one leaky cavity pressure sensing device to provide an input electrical pressure signal to the driver circuitry, the driver circuitry being responsive to the input electrical pressure signal by providing the output electrical pressure signal.