To prevent deterioration of sealing performance even when a foreign matter is caught between a valve seat and a seal surface by arranging a clearance in a part corresponding to at least a seal surface between a base body and a seal member while forming the seal surface on the seal member made of a flexible material stuck on the base body.
A valve element 31 is constituted by a base body 31a protuberantly arranging a guide shaft 31b on a center part, and an annular seal member 31c stuck on the upper surface of the body 31a so as to oppose to a valve seat 35. The upper surface of the seal member 31c formed as a seal surface, the upper surface is brought into push-contact with the valve seat 35 when the valve element 31 is pushed up, and thereby, a valve hole is closed. The annular clearance 31F is formed between the valve element 31 and the seal member 31c at a clearance L. An annular bead part 31e is protruberantly arranged on the upper surface of the seal member 31c. When the valve element 31 is pushed up by a needle and reciprocating motion is carried out. The top part of the bead part 31e as a sealing surface is brought into contact with the valve seat 35, then it is pushed up by the needle, and thereby, the sealing member 31c is loosened in a direction for narrowing the clearance 31f.
ONO MASAFUMI
MIZUNO HIROSHI
