Patent ID: 6878317

Claim:
An injection molding machine, comprising: electrically-driven die opening/closing means; and a hydraulic actuating mechanism including: a plurality of hydraulic actuators driven by one hydraulic pump, the hydraulic pump of said hydraulic actuating mechanism being a variable discharge pump configured to deliver a maximum necessary delivery capacity at least for each of said hydraulic actuators at the time of a highest rotational speed of said pump; and a plurality of four-way switching valves and at least one two-way switching valve provided between the variable discharge pump and said plurality of hydraulic actuators, the plurality of four-way switching valves and the at least one two-way switching valve being configured to control an operation of the plurality of hydraulic actuators, wherein the plurality of hydraulic actuators includes hydraulically-driven die clamping means, a discharged fluid pressure is controlled by a discharge cutoff function of a pressure compensator ancillary to said variable discharge pump, and said pump is driven by a motor whose rotation can be controlled in a stepless mode.