Miniature pressure sensor assembly

• US 7,980,139 B2
• Filed: 08/28/2008
• Issued: 07/19/2011
• Est. Priority Date: 10/18/2004
• Status: Expired due to Fees

• Current Assignee: Precision Mechatronics Pty Ltd
• Original Assignee: Silverbrook Research Pty Limited
• Inventors: Silverbrook, Kia, Mallinson, Samuel George
• Primary Examiner(s): Caputo, Lisa M
• Assistant Examiner(s): JENKINS, JERMAINE L
• Application Number:
  US12/200,842
• Publication Number:
  US 20080314136A1
• Time in Patent Office: 1,055 Days
• Field of Search: None
• US Class Current: 73/774
• CPC Class Codes: B60C 23/0408 transmitting the signals by non-mechanical means from the wheel or tyre to a vehicle body mounted receiver

Abstract

A miniature pressure sensor assembly is provided for fitting within the valve stem of a vehicle tire. The pressure sensor assembly typically includes a reference device for temperature compensation and a measurement device for pressure measurement. Each device includes a substrate assembly defining a plurality of holes. A deflectable membrane is mounted to the substrate assembly to define a first chamber. A cap is mounted to the membrane to form a second chamber.

Claims

1. A pressure sensor assembly for fitting within the valve stem of a vehicle tire, the assembly comprising:

a substrate assembly defining a plurality of holes;

a first deflectable membrane mounted to the substrate assembly to define a first chamber;

a first cap mounted to the membrane to form a second chamber;

a second deflectable membrane mounted to the substrate assembly adjacent the first deflectable membrane to define a third chamber; and

a second cap mounted to the second membrane to form a fourth chamber,

wherein the second chamber is open for exposure to tire pressure and the fourth chamber is closed.

2. A pressure sensor assembly as claimed in claim 1, wherein the second membrane defines a plurality of holes through which the third and fourth chambers are interconnected.

3. A pressure sensor assembly as claimed in claim 1, wherein the first chamber is a sealed chamber and the first cap defines a plurality of holes so that the second chamber is an open chamber.

4. A pressure sensor assembly as claimed in claim 1, wherein the pressure sensor assembly is a Microelectromechanical system (MEMS) formed using integration circuit fabrication techniques.

5. A pressure sensor assembly as claimed in claim 4, wherein the substrate assembly includes:

a silicon substrate layer;

a CMOS layer deposited on the silicon substrate layer;

a conductive layer deposited on the CMOS layer; and

a passivation layer deposited on the conductive layer;

wherein said plurality of holes pass through each layer.

6. A pressure sensor assembly as claimed in claim 5, wherein each membrane is conductive and the conductive layer and conductive membranes together form electrode pairs which develop a capacitance between them.

7. A pressure sensor assembly as claimed in claim 1, wherein each membrane is formed from non-conductive material which is in contact with piezo material.