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:
Jan. 19, 1993
Filed:
Oct. 15, 1991
Joseph H Hunter, Carmel, IN (US);
General Motors Corporation, Detroit, MI (US);
Abstract
The present invention provides a hydraulic control system for the automatic transmission of a vehicle. The control system utilizes only one pulse width modulating solenoid valve to provide modulated pressure (P2) to whichever of the torque transfer devices constitutes the single, on-coming torque transfer device required to effect a desired drive ratio. The control system includes a plurality of cascaded relay valves each of which is controlled by a respective solenoid valve. A pressure control gate is interposed between the single, pulse width modulating solenoid valve and the plurality of cascaded relay valves in order to provide modulated pressure (P2), or, selectively, main line pressure (P1) to the various torque transfer devices of the transmission. The solenoid valve are controlled to select which of the torque transfer devices shall be actuated by modulated pressure (P2) and which shall receive line pressure (P1). In addition, the control actuates a torque converter clutch with modulated pressure (P2) and maintains engagement thereof by main line pressure (P1) through selected drive ratios.