| 摘要 |
PROBLEM TO BE SOLVED: To prevent early opening of a valve disc. SOLUTION: A lid body 2 is fixed to a body 1 having an inlet 4 and an outlet 5 and a pressure changing chamber 3 is formed in an interior. A squirt hole 6 is provided opened in a center of the pressure changing chamber 3, and the inlet 4 is communicated with the pressure changing chamber 3. An annular groove 8 is provided in an outer periphery of the squirt hole 6, an annular inner ring valve seat 9 is formed between the squirt hole 6 and the annular groove 8, and an annular outer ring valve seat 10 coaxial and coplanar with the inner ring valve seat 9 is formed in an outer periphery of the annular groove 8. The valve disc 11 opened and closed by separation/seating to the inner and outer ring valve seats 9 and 10 is arranged in the pressure changing chamber 3. An inner ring seal ring 12 sliding on an outer circumferential wall of the squirt hole 6 is arranged on the squirt hole 6 and an outer ring seal ring 14 sliding on an outer circumferential wall of the annular groove 8 is arranged on the annular groove 8. Upper ends of the inner ring seal ring 12 and the outer ring seal ring 14 are projected slightly more than the inner and outer ring valve seats 9 and 10 during opening of the valve disc by a waveform spring 13 and a waveform spring 14.
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