Abstract: When a valve body of a coupling member is moving toward a fluid passage closed position, if the valve body becomes inclined, the present invention prevents a sealing ring of the valve body from coming into friction engagement with a conical wall surface of the fluid passage and coming to a stop. The valve body has a valve head provided with a disk-shaped portion, a sealing ring, and a sealing ring support that supports this sealing ring against the valve head; and an angle that a line tangent to a disk-shaped member of the valve head and sealing ring makes with respect to the axis of the valve body is less than or equal to an angle that the conical wall surface, forming the valve seat of the fluid passage, makes with respect to the axis of this fluid passage.

Abstract: When a valve body of a coupling member is moving toward a fluid passage closed position, if the valve body becomes inclined, the present invention prevents a sealing ring of the valve body from coming into friction engagement with a conical wall surface of the fluid passage and coming to a stop. The valve body has a valve head provided with a disk-shaped portion, a sealing ring, and a sealing ring support that supports this sealing ring against the valve head; and an angle that a line tangent to a disk-shaped member of the valve head and sealing ring makes with respect to the axis of the valve body is less than or equal to an angle that the conical wall surface, forming the valve seat of the fluid passage, makes with respect to the axis of this fluid passage.

Abstract: This invention provides a pipe coupling used for changing oil in an engine oil pan with an oil drain port. A drain plug has a drain plug main body having one end to be attached to the oil drain port of the engine oil pan, a recess formed in its outer surface of the other end projecting outward from the oil pan, and an axial oil flow path extending in an axial direction, a valve holder to be arranged in the plug main body, and a valve body held by the valve holder and capable of closing the flow path.

Abstract: A socket of a pipe joint has a socket body, coupled to an end portion of a first fluid pipe, for removably receiving a plug coupled to an end portion of a second fluid pipe to be coupled to the first fluid pipe, a valve mechanism provided within the socket body and situated in an open position to allow passage of a fluid between the socket body and the plug when the plug is inserted in the socket body, and a lock mechanism for preventing removal of the plug from the socket body when the valve mechanism is situated in the open position.

Abstract: A tube coupler of this invention, is provided with a plug and a socket each having a fluid passage and a valve. When the plug and the socket are connected together, they push each other to cause the fluid passage of the plug to communicate with the fluid passage of the socket. The socket has a main socket tube body comprising an inner tube and an outer tube provided separately and threadably engaging each other. The plug has a main plug tube body insertable between the inner and outer tubes. The tube coupler has a seal member mounted on the outer peripheral surface of the inner tube of the main socket tube body for sealing a gap between the outer peripheral surface of the main socket tube body and the inner peripheral face of the main plug tube body.