Patent ID: 8590860

Claim:
A male coupling member of a pipe coupling, the male coupling member comprising: a tubular coupling body having an inner peripheral surface defining a through-hole extending from a front end opening to a rear end opening, the inner peripheral surface having an annular opening surface parallel to an axis of the coupling body, the annular opening surface defining the front end opening, the inner peripheral surface further having a sloped annular valve seat surface diverging radially outward as the annular valve seat surface extends rearward from a circular rear end edge of the opening surface, and the inner peripheral surface further having a cylindrical surface extending contiguously rearward from the annular valve seat surface; a valve member set in the coupling body, the valve member having: a front end portion fitted into the front end opening; and a valve body extending contiguously rearward from the front end portion; the front end portion having a circular front end surface, a front end annular surface extending rearward from an outer peripheral edge of the front end surface and having a smaller diameter than the opening surface, and a reduced-diameter surface extending contiguously rearward from the front end annular surface and having a smaller diameter than the front end annular surface; the valve body having an annular seal member engageable with the annular valve seat surface of the coupling body; and a spring member urging the valve member forward to place the valve member in a closed position where the front end portion of the valve member is inserted into the front end opening and where the seal member is sealingly engaged with the annular valve seat surface, the spring member allowing the valve member to assume an open position where the seal member is separate from the annular valve seat surface when the valve member is displaced rearward by a rearward force applied to the front end surface of the valve member; wherein the reduced-diameter surface is configured such that when a rearward force is applied to the front end surface of the valve member, causing the valve member to tilt so that the front end surface tilts relative to an axis of the through-hole, resulting in the reduced-diameter surface engaging the circular rear end edge of the opening surface, a length from a point of engagement between the circular rear end edge and the reduced-diameter surface to the outer peripheral edge of the front end surface of the valve member through an axis of the valve member is equal to or smaller than a diameter of the opening surface.