The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jun. 10, 2008
Filed:
Mar. 29, 2007
Yingjie Lin, El Paso, TX (US);
Carlos A. Urquidi, Juarez, MX;
Francisco Romo, Juarez, MX;
Delphi Technologies, Inc, Troy, MI (US);
Abstract
A capacitive pressure sensor includes a electrically conductive, generally piston shaped diaphragm with a flexible base wall configured to deflect under pressure. The diaphragm is generally U-shaped in cross section. The base wall includes an upper, flat sensing surface which acts as a capacitive electrode. The diaphragm further includes a step around a radially-outermost perimeter which is elevated from the flat sensing surface. A sensing electrode body is located on top of the step and creates a capacitive sensing cavity between the sensing surface and the bottom surface of the electrode body. On the bottom surface of the electrode body is formed a center, circular electrode and a ring electrode that surrounds the center electrode. The center electrode and the sensing surface form a variable capacitor which changes with pressure and the ring electrode and the sensing surface form a reference capacitor. A circuit determines a differential capacitance between the variable capacitor and the reference capacitor and generates a pressure signal indicative of the fluid pressure applied to the diaphragm. A spring ring holds the sensing electrode body against the diaphragm when assembled. The diaphragm can be a machined metal part or a sheet metal cup. The sensing electrodes and signal generating circuit can take the form of a hybrid circuit.