| 摘要 |
PURPOSE:To prevent variation of flow characteristic due to variation of viscosity of pressure fluid under low temperature by forming a control restrictor with shape memory alloy storing such shape as the restrictor opening will be large under low temperature while small under normal temperature. CONSTITUTION:Pressure fluid is fed through a feed path 12 and a control restrictor 31 into first valve chamber 32 while further fed through a communication hole 23a and each orifice 24a, 24b and the delivery port 21a of an union 21 to a power steering system. Upon increase of flow of pressure fluid, a spool valve 22 will slide to make constant the differential pressure across both orifices 24a, 24b to open the bypath 13 thus to recirculate the excessive pressure fluid. Here the control sleeve 35 constructing a control restrictor 31 is formed with shape memory alloy to be changed into such shape as shown by solid line under low temperature. Consequently the opening of said restrictor 31 is enlarged to maintain the flow characteristic constant irrespective of increase of viscous resistance of pressure fluid. |
