| 摘要 |
PURPOSE:To perform good observation by keeping a proper amount of a air in the body cavity, by perfectly blocking the gap between a suction pipe and a suction channel by an O-ring in a stand-by state. CONSTITUTION:The gap between a suction pipe 4 and a suction channel 6 is perfectly blocked by two O-rings 23, 24 in a stand-by state and the suction pipe 4 communicates with the open air through an air passage 17 to suck the open air. When sucking operation is performed by pushing in a piston 21, the suction pipe 4 communicates with the suction channel 6 through a communication hole 26 to perform suction from the suction port at the leading end of an insert part. At this time, the air passage 17 is perfectly blocked from the open air by the O-ring 30 provided to the upper end part of the piston 21 and the open air is not sucked at all. When the piston 21 advances and retracts, the central O-ring 23 mounted on the outer periphery of the piston goes in and out through the lower end part of a sleeve 13 and, since the mouth part 13c of the lower end part of the sleeve is chamfered, the O-ring is not damaged or cut.
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