Abstract: A control valve for a variable assist power steering apparatus comprises a bypass line having one end connected to one of two parallel fluid flow paths of a distributor circuit at an inflow section thereof and an opposite end connected to the one fluid flow path at an outflow section thereof. The bypass line is arranged in parallel to primary variable flow restrictors and in series with secondary variable flow restrictors. An externally controlled variable flow restrictor is disposed in the bypass line.

Abstract: A control valve includes valve elements relatively displaceable in response to a steering torque to define therebetween two parallel fluid flow paths connected between a fluid source and a fluid reservoir to produce pressure difference in a power cylinder. The control valve comprises a bypass path including a first externally controlled variable flow orifice and a variable flow orifice variable with steering torque and a first externally controlled variable flow orifice valve which are connected in series, a second externally controlled variable flow orifice valve, and a second variable flow orifice variable with steering torque. The bypass path is arranged in parallel with a portion of the two parallel fluid paths, the second externally controlled variable flow orifice valve is arranged in parallel with another portion of the parallel fluid paths, and the second variable flow orifice is arranged in series in the remaining portion of the parallel fluid paths.