To enhance repetition reliability of a valve mechanism forming the face receiving an abutting member for opening of ribs comprising annular protrusions projecting from a piston type valve thereby equalizing the distance from the shaft part of the valve to the abutting part of each protrusions at the rib part.
Positional relation for canceling moments applied to two abutting positions around the shaft part of a valve 261 is preferable for the part of a joint pipe 180 where two valve opening/closing protrusions 180b abut against each other. The valve 261 is provided with annular ribs 311 having shape similar to that of the elongated hole type joint pipe 180. Furthermore, an elongated hole type recess 311a is provided in the center of the valve 261 except the valve seal part being brought into tight contact with a first seal part. According to the structure, the valve 261 is provided with strength and reliability at the time of abutting against the protrusion 180b. Furthermore, moldability of the valve can be enhanced because the ribs have annular shape and a recess is provided in the center.
HAYASHI KOKI
HATTORI SHOZO
KITAHATA KENJI
SHIMIZU EIICHIRO
YAMAMOTO HAJIME
