SEALING STRUCTURE AND CONTROL VALVE

摘要

PROBLEM TO BE SOLVED: To stabilize operation by sealing a gap D between a moving piston 12 and a cylinder 11 with an O-ring 15 and minimizing a change in sliding resistance to the fluctuation of differential pressure applied to the O-ring 15.

SOLUTION: An annular groove 13 is formed in the piston 12, and the O-ring 15 is fitted in the annular groove 13. A communicating hole 16 communicating with the low pressure-side gap D is formed in a space S1 formed of a low pressure-side side surface 13a and a low pressure-side projection 13a1 of the annular groove 13 and the O-ring 15. Low pressure at a secondary chamber side communicating through the gap D between an insert hole 11a and the piston part 12 is applied to the O-ring 15 through the communicating hole 16. High pressure at a pressure equalizing chamber 1f side communicating through a high pressure passage 14 is applied to the O-ring 15. The O-ring 15 is pressed to the insert hole 11a by the differential pressure between the low pressure and the high pressure to seal a gap between the cylinder 11 and the piston 12. A force deforming the O-ring 15 toward the cylinder 11 is dispersed to the communicating hole 16 side.

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