Patent ID: 6807895
Filing Date: 2004-10-26
Classification: F15B,H04N

Abstract:
A 3-position stopping cylinder comprising:a hollow cylinder main body which has a head side end wall and a rod side end wall at its both ends; a main piston which is disposed in the interior of the cylinder main body slidably in an axial direction thereof and where a rod side pressure receiving face to which a piston rod is attached and a head side pressure receiving face opposed thereto are different in pressure receiving area from each other; a head side pressure chamber and a rod side pressure chamber which are formed on both sides of the main piston; a pusher which is disposed in the interior of the cylinder main body at a position closer to the head side end wall or the rod side end wall rather than the main piston so as to be movable in the axial direction independently from the main piston and which has a stroke shorter than that of the main piston and serves as both means for pushing the main piston from a stroke end back to an intermediate stopping position and means for stopping the main piston at the intermediate stopping position; and pressing means for causing the pusher to displace up to the intermediate stopping position, wherein: the pusher is formed in a hollow sleeve shape and the pressing means is a spring; and the pusher is disposed in the interior of the cylinder main body at a position closer to the rod side end wall rather than the main piston in a state that the pusher has been supported via its outer periphery thereof to an annular guide portion provided to the cylinder main body, the piston rod penetrates the interior of the pusher, a distal end portion of the pusher projects into the rod side pressure chamber and a rear end portion thereof abuts on the spring, and the pusher has a stopper engaged with the guide portion at a position of an advance end thereof.