| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a hydraulic unit for an industrial machine such as a machine tool, causing no problems of a loss and noise in an inverter and a decrease in efficiency of a pump drive motor and in addition, shortening time required until the rotational speed of the pump drive motor (hydraulic pump) is switched from a low speed to a high speed in order to return hydraulic pressure. <P>SOLUTION: This hydraulic unit 21 for the machine tool includes the pump drive motor 22 and the hydraulic pump 23, and rotatively drives the hydraulic pump 23 by the pump drive motor 22, thereby supplying oil delivered from the hydraulic pump 23 to a hydraulic cylinder 36 as the hydraulic drive source of an actuator. The pump drive motor 22 is a pole change motor. The rotational speed of the pump drive motor 22 is switched from the low speed to the high speed based on an actuator movement command. <P>COPYRIGHT: (C)2012,JPO&INPIT |
