| 摘要 |
<p>1,084,927. Power steering systems. FORD MOTOR CO. Ltd. Aug. 26, 1966 [Oct. 11, 1965], No. 38376/66. Heading B7H. [Also in Division F2] A motor vehicle power steering system includes a pump assembly comprising a positivedisplacement pump 25 and a by-pass valve 45 for by-passing part of the pump output to the pump inlet to control flow through a discharge outlet 17 from the assembly in such a way that the flow from the discharge outlet is reduced when the pump output reaches a certain value. A valve chamber 92 receiving the pump delivery through an inlet 93 contains a spring-loaded valve spool 95 which controls the size of a bypass orifice 106 connected to the pump inlet and carries a metering rod 101 controlling the size of a discharge orifice 96 connected to the outlet 17. The end of the spool 95 remote from the inlet 93 is subjected through a passage 105 to the pressure downstream of the discharge orifice 96. As the pump output rises with engine speed, a constant diameter portion 1 of the rod 101 first occupies the discharge orifice 96 so that delivery from the outlet 17 increases with speed until the spool 95 begins to uncover the by-pass orifice 106 and delivery is maintained constant. At a predetermined pump output, a tapering portion 104 of the rod 101 begins to move through the discharge orifice 96 to provide a progressively decreasing delivery until a larger diameter portion 103 of the rod occupies the discharge orifice 96 and delivery remains constant at a reduced rate. A spring- loaded ball-valve 51 relieves excess pressure at the outlet 17. The pump 25 and valve housing 36 are mounted in the pump housing 11 on a pair of dowels (Fig. 3, not shown) and are urged into sealing engagement with each other and the end wall of the housing 11 by a pair of springs (Fig. 2, not shown). A reservoir 14 surrounding the housing 11 includes a return flow connection 16 and communicates with the pump inlet through an opening 61.</p> |
