| 摘要 |
A shut-off valve with a valve-closing member, guided movably in a housing, in the form of a main piston with differential areas which are acted upon in opposite directions by the high pressure of the medium to be regulated has a pilot control valve which is controllable by fluid, which, with a control piston that can be acted upon by the fluid, is aligned axially with the main piston and interacts via a plunger of the control piston with a pilot control valve on the main piston. The main piston is bridged by a restrictor which connects the high-pressure side of the valve to the pilot-control side of the main piston. The main piston is furthermore penetrated by a hole which connects the seat of the pilot control valve to the low-pressure side of the valve radially within the seating surface. The main piston thus floats in the medium to be regulated. The differential surfaces on the main piston which are acted upon by the high pressure, and the cross-sections of the restrictor and the hole in the main piston are dimensioned in such a way that a resultant pressure is exerted on the main piston in the closing direction when the control piston is actuated and the seat of the pilot control valve is blocked by the plunger. This construction has the effect of gentle opening and closure of the valve and the avoidance of pressure shocks.
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