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:
Nov. 12, 1991
Filed:
Jul. 20, 1989
Carl A Lentz, Mooresville, 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 valve to provide modulated pressure to whichever of the torque transfer devices--in the nature of clutches and brakes--constitutes the single, on-coming torque transfer device required to effect the drive ratio selected in accordance with electrical control signals from an on-board, pre-programmed computer. The control system accomplishes its objective by cascading a plurality of relay valves which are coupled to preferably latching, solenoid valves (A through E) which are also controlled by computer. A control valve is interposed between the single, pulse width modulating valve and the plurality of cascaded relay valves to provide both modulated pressure (P.sub.3) and main line pressure (P.sub.1) to the various torque transfer devices of the transmission. The computer controls the solenoid valves (A through E) to determine which of the torque transmitting devices shall receive line pressure (P.sub.1) and which shall receive modulated pressure (P.sub.3). In this regard it is noted that the on-going torque transfer device is always actuated by modulated pressure (P.sub.3). Moreover, the control system is adapted for operation with vehicular transmissions that provide one more forward drive ratio than the number of torque transfer devices in the transmission.