Patent ID: 6387000
Filing Date: 2002-05-14
Classification: F04C,F16H

Abstract:
A pressure medium supply arrangement for a CVT transmission, said arrangement comprising:a pump (30) configured to supply pressure medium to control cylinders (22, 24) of the CVT transmission to change a gear ratio of the CVT transmission; said pump (30) having a high pressure side and a low pressure side; said pump further having a bypass channel (62) connecting said high pressure side and said low pressure side; an electrically controlled control valve arrangement (28) connected to said pump (30) and configured to open and close said bypass channel (62) for adjusting a conveyed flow of said pump (30); wherein said pump (30) is a rotary piston pump having a pump housing with displacement chambers, wherein said rotary piston has a pressure plate (42) closing off an end face of said displacement chambers, wherein said pressure plate (42) is configured to be movable between a sealing position and an open position, wherein said pressure plate (42) has a backside remote from said displacement chambers, wherein said control valve arrangement (28) is connected to said backside and supplies the pressure medium to said backside as a control pressure, wherein said control pressure controls said sealing position and said open position, and wherein said open position defines said bypass channel (62); wherein said control valve arrangement (28) comprises a 3-port pressure regulator (68) having a valve housing with a pressure connector (P), a return connector (S), and a control connector (C) connected to said backside, wherein said pressure regulator (68) further comprises a piston movably guided in said valve housing, wherein said control valve arrangement (28) has a metering orifice (66), positioned between the control cylinder (24) and said pump (30), wherein said piston is loaded by a first force provided by the pressure upstream of said metering orifice (66) and by a second force provided by the pressure downstream of said metering orifice (66), wherein said control valve arrangement (28) further comprises a solenoid acting on said piston as a third force, wherein an increase of said third force moves said piston in a first direction in which said control pressure increases and a decrease of said third force moves said piston in a second direction in which said control pressure decreases.