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:
Apr. 23, 1991
Filed:
Aug. 02, 1990
Ronald J Goubeaux, Lockport, NY (US);
Edward D Pettitt, Burt, NY (US);
General Motors Corporation, Detroit, MI (US);
Abstract
A low charge protection method for an electronically controlled variable displacement compressor. In each period of compressor operation, a low charge test sequence is carried out to monitor the system performance once the system control pressure has been reduced below a specified level. In a set-up phase of the test, the compressor is down-stroked to near-minimum displacement for a predetermined time or until the system control pressure rises above a reference level. At such point, the compressor is up-stroked to near-maximum displacement to initiate a pull-down phase of the test. If the system pressure is reduced by specified amount within a reference interval, a failed test is indicated and the count in a nonvolatile counter is incremented. If the pull-down duration exceeds the reference interval, a passed test is indicated, and the count, if any, is decremented. When the nonvolatile count exceeds a specified threshold, the compressor is disabled and further operation is prevented until the count is reset by a service technician.