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:
Feb. 01, 1977
Filed:
Nov. 17, 1975
John W Riddel, Fenton, MI (US);
General Motors Corporation, Detroit, MI (US);
Abstract
A differential pressure control valve is solenoid operated on a controlled duty cycle to alternately open and close a pair of inlets to establish a desired outlet pressure. The valve member acts as a solenoid armature. It is of sandwich construction with a magnetically soft center section and a thin, wear-resistant, nonmagnetic coating on one or both sides. The nonmagnetic coatings or layers are disclosed as being made of a nonmagnetic stainless steel, while the center section is disclosed as being made of a low carbon steel having a low magnetic remanence or residual magnetization. Valve life is increased due to the wear resistance of the stainless steel, and the nonmagnetic characteristic of the stainless steel layer adjacent the field plate avoids erratic retention of the valve member against the solenoid core and field plate. The arrangement is such that the magnetic forces across the valve member during solenoid energization act in parallel.