| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a hydraulic unit which can secure the torque required for low-speed rotation of a variable speed motor used for performing rotary drive of a variable displacement hydraulic pump and which can achieve greater energy conservation. <P>SOLUTION: The hydraulic unit includes the variable displacement hydraulic pump 1, the variable speed motor 5, a pressure sensor 7, and a controller 8. The variable displacement hydraulic pump 1 has a pressure adjustment mechanism used for mechanically controlling the position of a swash plate 2 by hydraulic control based on discharge pressure. The variable speed motor 5 performs rotary drive of the variable displacement hydraulic pump 1, and the pressure sensor 7 detects the discharge pressure of the variable displacement hydraulic pump 1. The controller 8 outputs a control signal which controls the variable speed motor 5 at the predetermined rpm in correspondence with the pressure detected by the pressure sensor 7. The variable speed motor 5 is constituted by a servomotor 5 which is provided with an encoder 6 which outputs a feedback signal in accordance with the detected rpm. Furthermore, a servo amplifier 9 is connected to the controller 8, and the servo amplifier 9 outputs a rotation speed signal which is based on the deviation between the control signal from the controller 8 and the feedback signal from the encoder 6 to the servomotor 5. <P>COPYRIGHT: (C)2009,JPO&INPIT</p> |
