| 摘要 |
A power steering apparatus is composed a fluid source for discharging pressurized fluid, a power cylinder, a control valve responsive to operation of a steering wheel for supplying the power cylinder with pressurized fluid from the fluid source, and a reservoir. The control valve has a first control portion for controlling the flow of pressurized fluid from the fluid source to the reservoir, and a second control portion for controlling the flow of pressurized fluid to the power cylinder. The first control portion has four paths communicating with the fluid source and the reservoir, and each of the four paths is formed with a center-open variable orifice which opens when the control valve is in a neutral state. The second control portion has two supply paths communicating with the fluid source and a pair of chambers of the power cylinder, each of the two supply paths is formed with a semi-center-open variable orifice which opens when the control valve is in the neutral state, and two drain paths communicating with the chambers of the power cylinder and the reservoir, each of the two drain paths is formed with a center-closed variable orifice of which closes when the control valve is in the neutral state.
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