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.
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.
OSAWA KAZUHIKO
KITANO SHINICHI
| JPH0464679U | 1992-06-03 | |||
| JP2008039060A | 2008-02-21 | |||
| JP2004116550A | 2004-04-15 | |||
| JP2010185533A | 2010-08-26 | |||
| JP2003166655A | 2003-06-13 | |||
| JP2006522297A | 2006-09-28 | |||
| JPS49101934A | 1974-09-26 | |||
| JPH11218236A | 1999-08-10 |
Sadao Matsumura
Fumio Takino