| 摘要 |
PURPOSE:To obtain drooping characteristics with simple structure by providing an orifice that opens a spool valve in a cylindrical union adhering to the opening section of a spool valve housing hole and then a limit path between the orifice and a pump. CONSTITUTION:An orifice is formed on a union 4 that is fixedly screwed in the housing hole 2 for a spool valve 3 of a housing 1. In addition, a flow-rate limit path 19 is configured with the flange 16 of a sleeve 17 slidably fitted on the union 4 and the inner surface of the hole 2. In the low speed rotation range of the pump 6, a supply path 5 is disconnected from a circulation path 7 and the total amount of exhaust oil is supplied to a power steering device. When the number of revolution of pump is increased, a spool valve 3 moves right by the differential force before and behind an orifice 12, both paths 5 and 7 are opened, and excessive flow is circulated. Besides, when the number of revolution is increased, the sleeve 17 is moved right by the differential force before and behind the limit path 19 and the orifice 12 is throttled. As a result, the spool valve 3 is further moved right and the amount of reflux is increased. |
