DISCHARGE OIL CONVERGE FEED DEVICE FOR VARIABLE-DISCHARGE QUANTITY PUMP AND CONSTANT-DISCHARGE QUANTITY PUMP

摘要

PURPOSE:To secure a constant flow regardless of the load pressure by providing a fixed throttle and a cartridge valve on the pressure oil feed line of a fixed- displacement pump, and providing a pressure compensating valve between the discharge side of the fixed-displacement pump and a tank. CONSTITUTION:The discharge oil from a fixed-discharge quantity pump 2 is converged to the discharge oil discharged from a variable-discharge quantity pump 1 and passing an electromagnetic proportional flow control valve 3 and a check valve 4 and fed to a load such as an injection molding machine. A fixed throttle 15 and a cartridge valve 20 are provided on the pressure oil feed line L2 of the fixed-displacement pump 2. A pressure compensating valve 16 with the function of an unloading valve is provided between the discharge side of the pump 2 and a tank on the pressure oil feed line L2. One of the X-port of the cartridge valve 20 and the vent port of the pressure compensating valve 16 is selectably connected to the outlet side of the fixed throttle 15, and the other is connected to the tank.