| 摘要 |
PURPOSE: To improve the energy efficiency of a system by providing a pressure compensating mechanism provided with an intermediate pressure piston, providing a solenoid valve, and constituting a preset pressure so that it can be switched in three stages, to generate a pressure used in the hydraulic system as the pressure approximate to a necessary pressure. CONSTITUTION: Two solenoid valves 16a, 16b and a pressure compensating mechanism 17 having an intermediate pressure piston 19 are provided in a control mechanism for a variable displacement hydraulic pump of including a swash plate 12. Information 14 from a hydraulic system is processed in a controller 13, to on/off operate each solenoid valve 16a, 16b, and by pump delivery oil 34 fed to a pressure chamber 18 or 20 of the pressure compensating mechanism 17, the intermediate pressure piston 19 and high pressure piston 21 are actuated, to switch the initial preset height of a spring 22 into three stages. That is, the solenoid valve 16a is off-operated for high pressure setting, to on-operate both the solenoid valves 16a, 16b for intermediate pressure setting, to on-operate the solenoid valve 16a and to off-operate the solenoid valve 16b for low pressure setting. |
