Pipe coupling

A pipe coupling which has a socket and a plug connectable to each other, comprising:

• a plug body having a distal end portion, an axial bore opening in the distal end portion, and an outer peripheral portion on which a projection is formed;
• a socket main cylinder having first and second end portions and an axial bore which extends between the end portions and through which a fluid can flow;
• a ball valve which has a through bore formed having one end capable of receiving the distal end portion of the plug body and the other end portion capable of communicating with the axial bore, is located at a first end portion of the socket main cylinder, and controls the axial bore in an open-close condition;
• an annular seal unit located near the first end portion in the axial bore and having a distal end portion formed having a ball valve receiving surface in sealed engagement with the ball valve;
• a casing which has a base portion fixed to the first end portion of the socket main cylinder, a top portion opposed to the base portion, a flank portion located between the first end portion and the top portion, and a slot extending from the flank portion to the top portion and which supports the ball valve in conjunction with the ball valve receiving surface, the slot having a flank opening, which is aligned with the one end of the through bore and through which the projection of the plug body can be passed when the other end of the through bore is disconnected from the axial bore of the socket main cylinder, and a top opening, which is aligned with the one end of the through bore and engages the projection when the other end of the through bore communicates with the axial bore of the socket main cylinder, so that the ball valve is rocked by the plug body in the one end of the through bore between a position in which the other end of the through bore communicates with the axial bore of the socket main cylinder and a position in which the other end is disconnected from the axial bore;
• and
• a lock element located for reciprocation in the through bore of the ball valve, the lock element being urged toward the one end and adapted to move into the flank opening to prevent the ball valve from rocking with respect to the casing when the one end of the through bore of the ball valve is aligned with the flank opening and to move into the through bore of the ball valve to allow the ball valve to rock with respect to the casing when the plug body is inserted into the one end of the through bore.