| 摘要 |
A steering gear unit for a power steering system is provided to achieve optimum steering stability during a high speed driving by preventing a hydraulic power assist due to hydraulic pressure. A steering gear unit for a power steering system includes a housing(1). A torsion bar(3) is connected to a handle inside the housing. An input shaft(5) is connected to an upper part of the torsion bar. A pinion shaft(7) is connected to a lower part of the torsion bar. A rotary valve(11) is formed on an outer circumference of the input shaft. A coupling unit is interposed at the upper part of the rotary valve on the input shaft. A PCS(Positive Centering Spring,15) supports the coupling unit. A supply passage(L1) is connected to the housing by a hydraulic pump(17). A cut off valve is mounted on a cut off valve chamber(21). The PCS is mounted on a spring chamber. A spring chamber passage(L2) is divided from the supply passage and supplies an oil pressure to the spring chamber. A steering solenoid valve(27) is installed on one side of the housing to open the spring chamber passage and is controlled by a controller(25). A torsion prevention unit allows a guide pin(31) to be inserted to or separated from a space(S) so as to block torsion of the torsion bar.
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