| 摘要 |
<p>A pressure control device in which a drive piston (17) and a pressure control valve (24) are movably supported in a housing (11) and urged in it. This enables a pressure chamber (R<SUB>3</SUB>) and a pressure reduction chamber (R<SUB>2</SUB>) to be communicated with each other. Also, the drive piston (17) and the pressure control valve (24) are moved via an annular piston (19) by electromagnetic force of a solenoid. This enables a high-pressure chamber (R<SUB>1</SUB>) and the pressure chamber (R<SUB>3</SUB>) to be communicated with each other. Further, an external piston (30) is movably provided so as to face the drive piston (17), and control pressure acting from a rear pressure chamber (R<SUB>32</SUB>) on the drive piston (17) side is set higher than external pressure acting from the outside by operation of an input section (36). This enables a drive valve to be easily moved by pressure from the outside when the electric power source fails, allowing appropriate pressure control.</p> |
