CLOSED HYDRAULIC CIRCUIT SYSTEM

摘要

A closed hydraulic circuit system (100) capable of driving a hydraulic cylinder (3) having a first port (3b) and a second port (3c) comprises: a hydraulic pump (1) which has a first pump port (1a) hydraulically connected to the first port (3b) through a first conduit (C1) and which also has a second pump port (1b) hydraulically connected to the second port (3c) through a second conduit (C2); an electric motor (2) which controls the rotation of the hydraulic pump (1); an electric motor control unit (11) which feedback-controls a value relating to an input to the hydraulic motor (2) on the basis of a value relating to an output from the electric motor (2); and a pump state determination section (13) which determines the state of the hydraulic pump (1) on the basis of the value relating to the input to the electric motor (2) and on the basis of the value relating to the output from the electric motor (2).