Patent ID: 8870037

Claim:
A plug structure used for a container whose cap attachment screw of a container inlet port is an outer screw, configured to be attached to the container inlet port, and provided with a siphon tube for taking out liquid in the interior of the container, comprising: a plug body to be press-fitted into the container inlet port being resiliently deformable in a radial direction at a lower portion thereof; a locking claw provided on an outer peripheral surface of the lower portion of the plug body, extending outwardly from the outer peripheral surface in direct engagement with an inner wall surface of the container inlet port; and a socket including a socket body, a sleeve, and an O-ring; wherein the sleeve is attached to the container by engaging its inner screw with the outer screw of the container in a state in which the socket body is inserted into the plug body to a predetermined position; wherein the O-ring seals a liquid flow channel in which the siphon tube and the liquid outlet flow channel penetrating through the socket body in an axial direction thereof are in communication with each other; wherein the plug body is fixed in the interior of the container inlet port by the resiliency of the lower portion provided with the locking claw; wherein a valve operating portion which presses a valve body of a valve for discharging liquid provided on the socket to open is provided at an upper end inlet port of the siphon tube; and wherein A>B>C is satisfied: where A is an effective screw length of the inner screw formed on the sleeve; B is an attachment distance between the O-ring and an end surface of the plug-receiving opening in the socket; and C is a lower end projecting distance between the valve body and the end surface of the plug-receiving opening in the socket; and wherein the upper end inlet port of the siphon tube engages the end surface of the plug-receiving opening in the socket.