DRIVE UNIT BY OIL PRESSURE CLOSED CIRCUIT

摘要

PURPOSE:To prevent receiving effects OF oil temperature by composing a drive unit in such a way that an electric signal is outputted to an electric oil pressure converting means based on a detection signal of a motor resolution number so as to satisfy the relation of a differential pressure to a predetermined motor revolution number. CONSTITUTION:When a changing signal is applied to a solenoid part 14S of a direction control valve 14, the valve 14 is changed to a position (f), and the primary pressure of an electromagnetic proportional reduced pressure valve 31 (electric oil pressure converting means) is guided to a right chamber 17a of an inclined rotation cylinder 17, while the secondary pressure is guided to a left chamber 17b. A piston 17c of a cylinder 17 is displaced left for the differential pressure (secondary pressure - primary pressure) of the valve 31 to discharge pressure oil to a main conduit 18A. The secondary pressure of the valve 31 is adjusted by an output of a valve drive signal having a preset relation from a controller 34 to a solenoid part 31S of the valve 31 based on a pulse signal from a revolution number senser 33 corresponding to the revolution number of a motor 13. The differential pressure of the valve 31 is thus used, so effects of oil temperature are not given. The relation between the motor revolution number and the differential pressure is set as desired.