Fluid pressure operated impact mechanism

摘要

A fluid pressure operated impact mechanism of the type having a reciprocating working member guided for movement along an axis toward and away from a stop member, a pressure chamber between the working and stop members to receive a fluid pressure medium to exert forces separating the two members, and pressure sealing means for maintaining the pressure chamber sealed as the working member and stop member separate. The mechanism is characterized by a sealing arrangement which requires few precision parts yet is applicable to a variety of different devices. In the sealing arrangement, the pressure chamber is formed in the surface of at least one of the members, so that the two members meet along a separating line at the periphery of the pressure chamber. One of the members forms a support wall or flange extending in an axial direction along the separating line, and a flexible sealing means extends from the support wall of the one member to the other member, thereby effecting a seal therebetween. The sealing means is supported radially against the outward force of the pressure medium by the support wall, and is arranged to be elastically deformed in the axial direction by the pressure medium, thereby to maintain the pressure chamber sealed as the working member separates from the stop member. When the limit of deformation is reached and the seal is broken, the sealing means elastically returns to its relaxed condition to vent the pressure medium from the chamber and to permit the working member to reciprocate back toward the stop member to again form a seal therebetween. The sealing means, which can be an O-ring or bellows, preferably has an axial dimension when relaxed of just less than twice the axial height of the support wall.