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:
Mar. 31, 1987
Filed:
Dec. 21, 1984
Toyota Jidosha Kabushiki Kaisha, Toyota, JP;
Abstract
A hydraulic control system for a continuously variable transmission having a cylinder for changing the effective diameter of a pulley to control a speed ratio of the transmission. The control system comprises a spool valve assembly communicating with the cylinder to control the supply and discharge flows of a fluid to and from the cylinder. The valve assembly comprises a shift-speed control valve unit for controlling a rate of variation in the speed ratio of the transmission. The shift-speed control valve unit has only two discharge ports associated with the fluid discharge from the cylinder. The shift-speed control valve unit may take the form of a spool valve having a spool axially movable to open and close the ports to permit and restrict the fluid flows through supply and discharge conduits communicating with the ports and the cylinder. The spool may only partially open the corresponding port to permit the fluid flow therethrough for supplying or discharging the fluid. The valve assembly may comprise a shift-direction switching valve unit for changing the direction in which the speed ratio is varied. The switching valve unit has only two discharge ports associated with the fluid discharge from the cylinder.