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:
Jul. 24, 2007
Filed:
Sep. 29, 2005
Kenneth J. Cinpinski, Ray, MI (US);
Vimesh M. Patel, Novi, MI (US);
Kenneth J. Cinpinski, Ray, MI (US);
Vimesh M. Patel, Novi, MI (US);
GM Global Technology Operations, Inc., Detroit, MI (US);
Abstract
A method for diagnosing malfunctions of switching valve lifters includes sensing variations in pressure of trapped oil in a drive chamber of a hydraulic camshaft drive, such as a cam phaser, comparing peak oil pressure readings in the drive chamber resulting from the increased torque of opening the valves of various cylinders of an engine and identifying cylinders having lower than normal valve opening pressure readings, indicating failure of an associated valve lifter to properly actuate a valve of the cylinder. Apparatus for indicating such malfunctions could include a cam phaser with pressure chamber, a pressure sensor connected to indicate pressure variations in the chamber; and a pressure indicator connected to the sensor and adapted to indicate actual pressure variations for comparison with normal variations to identify low pressure peaks indicating malfunction of a switching lifter. A computer could be used to receive and act upon the malfunction indications.