Patent ID: 7921875

Claim:
A fluid coupling comprising a plug and a socket that are connectable to each other in a liquid-tight manner, the plug including a valve, a valve holder and a spring accommodated inside of the plug, the spring being adapted to apply an urging force to the valve so that the valve makes pressure contact with a valve seat formed on an inner peripheral face of the plug, the socket including a valve, a valve holder and a spring accommodated inside of the socket, the spring being adapted to apply an urging force to the valve so that the valve makes pressure contact with a valve seat formed on an inner peripheral face of the socket, wherein when the plug is inserted into the socket, the valve of the plug and the valve of the socket make contact with each other so that the valves are retracted so as to resist the urging force of the springs to connect the fluid passage of the plug with the fluid passage of the socket, wherein each of said springs is a conical coil spring that forms a conical external shape along a line connecting an outside diameter portion of the valve and an outside diameter portion of the valve holder when the valve of the plug and the valve of the socket make contact with each other so that the springs are compressed between the valve and the valve holder, wherein each of the conical coil springs has a small diameter portion and a large diameter portion, wherein the small diameter portion of the conical coil spring has substantially the same diameter as the outside diameter of an annular portion which supports the spring and through which a valve shaft of the corresponding valve passes, wherein the large diameter portion of the conical coil spring has substantially the same diameter as an outside diameter of the corresponding valve, and wherein, when the valve of the plug and the valve of the socket make contact with each other so as to compress the conical coil springs, coils of the conical coil spring in the plug approach each other and coils of the conical coil spring in the socket approach each other.