| 摘要 |
PURPOSE:To obtain the function of an unloading valve in a simple structure by forming a gap between the outer surface of a spool and the inner surface of a valve hole, and thereby making it possible that oil within a chamber to which pressure at the downstream side of an orifice is introduced, flows back to a circulating passage through the gap. CONSTITUTION:When the pressure at the side of an accumulator 50 is raised up to a specified one, which is sensed by a pressure sensor 66, electric current to a solenoid 62 is turned off so that a device is excited, then, a rod 64 is moved to the left in order to let an orifice be closed. When oil supply from the upstream side 55a of a feeding passage 55 to the downstream side 55b thereof is interrupted, oil within a chamber 4b housing a spring 56 in passes through a gap 58 between the circumferential surface of a spool 49 and the inner circumferential surface of a valve hole 4a so as to leak out to a circulating passage 4f. Then, the chamber 4b is reduced in pressure so that the spool 49 is moved leftward to a position where the pressure is balanced with one in the right side chamber 4d of the spool 49, that is, a position where the whole of oil supplied flows in the circulating passage 4f, so as to be in an unloading condition. |
