| 摘要 |
<p>An improved fluid flow control apparatus is utilized in association with a vehicle having a single variable displacement pump for supplying fluid to both a steering apparatus and an auxiliary apparatus. The fluid flow control apparatus includes a pair of variable size orifices one of which is associated with the steering apparatus and the other of which is associated with the auxiliary apparatus. Upon actuation of either the steering or auxiliary apparatus, the size of the associated orifice is varied to provide a variation in a load signal and effect a change in the displacement of the pump. During simultaneous operation of both the steering and auxiliary apparatus, a priority valve assembly is utilized to block fluid flow to the auxiliary apparatus if the fluid output from the pump is insufficient to satisfy the demand for steering fluid. The priority valve assembly includes a main valve member with an internal chamber in which a secondary valve member or piston is disposed. Upon initiation of a steering operation with the auxiliary apparatus in an inactive condition, the secondary valve member moves toward a closed position. If at this time the demand for steering fluid is sufficiently great, the secondary valve member blocks fluid flow to the auxiliary apparatus.</p> |
