To provide a tire booster for surely closing an exhaust valve in a state where drive of a motor is stopped.
A counterbore part 306 is recessedly formed on the outer side of a back wall 212A of a cylinder body 212, and an exhaust valve element 255 is mounted on a seat part 308 arranged on an outer surface of the back wall 212A. A projecting part 314 becoming thicker than a part for opening/closing an exhaust port 252 is formed at an outer edge of the exhaust valve element 255, and the projecting part 314 is pressed to be crushed in a state where a cylinder head 251 is fixed to the cylinder body 212 by a pressing rib 304 formed on the cylinder head 251. Thereby, pressing force toward the counterbore part 306 side resultantly acts on an exhaust valve 256, the exhaust valve 256 comes into surface contact with a bottom face 306A of the counterbore part 306, and the exhaust port 252 is closed. That is to say, floating of the exhaust valve 256 is suppressed, and the exhaust port 252 can be surely closed in a state where drive of a motor is stopped (the exhaust valve is closed).
SAKINO YOSHIKAZU
Kato Kazunori
Hiroshi Fukuda