ACTUATOR

To provide an actuator capable of retaining a shaft center of a piston even in an actuator mounted in piping of a large flow rate and having a large piston diameter.SOLUTION: An actuator includes: an actuator cap 3 defining a cylinder 30 inside; a piston 2 kept into slide-contact with the cylinder 30 via a slide body 20; a stem 4 connected to the piston 2 and engaged with a valve element 6; an elastic member 5 pressing and energizing the piston 2 to one side; and a working fluid supply port 30A for supplying a working fluid in a direction against the pressing of the elastic member 5. A peripheral projection is formed on an outer peripheral surface of the piston 2, and the slide body 20 in which an outer peripheral surface and an inner peripheral surface are formed into a parallel arc shape and which has a groove portion formed on the inner peripheral surface, is fitted to the peripheral projection of the piston 2.SELECTED DRAWING: Figure 1 【課題】流量の大きな配管に取り付け、ピストン口径の大きいアクチュエータでもピストンの軸心を保つことのできるアクチュエータを提供する。【解決手段】内部がシリンダ３０となるアクチュエータキャップ３と、シリンダ３０と摺動体２０を介して摺接するピストン２と、ピストン２と連結され、弁体６と係合するステム４と、ピストン２を一方に押圧付勢する弾性部材５と、この弾性部材５の押圧に抗う方向に、作動流体を供給するための作動流体供給口３０Ａとを備え、ピストン２の外周面には、周状突起を形成し、外周面と内周面とが平行な弧状をなし、内周面に形成した溝部を備えた摺動体２０を、ピストン２の周状突起に嵌合するようにしている。【選択図】図１