| 摘要 |
PURPOSE:To maintain the temperature of operating liquid at an appropriate temperature by detecting the temperature of the liquid in four steps and by automatically controlling the switching of passages so that the hydraulic circuit is adapted to each temperature ranges. CONSTITUTION:When temperature sensors 10 through 12 detect a super-cooled range, a first directional control valve 13 blocks the communication between a pump 2 and a hydraulic cylinder 7 and establishes the communication between the pump and the first restricting orifice 8, and a second directional control valve 14 closes all ports. When the temperature sensors detect a low temperature range, the first directional control valve 13 establishes the communication between the pump 2 and the hydraulic cylinder 7, and the second directional valve 14 establishes the communication between the pump 2 and a second restricting orifice 9 and as well communicates a return pipe line with a tank 1. When an appropriate temperature range is detected, first directional control valve 13 communicates the pump 2 with the hydraulic cylinder 2, and the second directional control valve 14 takes its block position. Further, the second directional control valve 14 communicates the pump 2 with the return pipe line 17 when an overheated range is detected. |
