| 摘要 |
PURPOSE:To reduce the variation of the load of a steering apparatus by installing a fixed orifice into a pump discharge passage and constituting a variable orifice in a feeding flow passage so that the opening area becomes smaller as the differential pressure between the front and back of the fixed orifice becomes larger. CONSTITUTION:In the low-speed revolution range of a pump driven by an engine, a spool valve 4 contacts with a stopper 11 by means of a return spring 4a, and the range 4b cuts-off a discharge passage 1 and a return passage 2. As for a variable orifice valve 5, the first flow-rate determining pin contacts with the valve-hole edge wall by the return spring, keeping the max. opening area, and all the discharge flow-rate of the pump flows into feeding flow passages 3 and 3', and the pump discharge flow-rate and the control flow-rate are made proportional. When the control flow rate reaches a constant value, the spool valve 4 is moved rightward by the pressure difference between the front and back of the variable orifice valve 5, and the rand 4b allows the discharge passage 1 to communicate to the return passage 2, and the control flow rate can be kept constant. |
