Patent ID: 7141166

Claim:
A drain structure of a fluid filter, the drain structure comprising: a main body; a cap that is detachable from the main body, the cap defining a drain hole that communicates with an inside of the main body; a drainpipe that is detachable from the drain hole and is able to be inserted into the drain hole; a valve member that blocks the drain hole at least when the drainpipe is detached from the drain hole; a cap side rib that is provided to the cap; a pipe side rib that is provided to the drainpipe to seal with the cap side rib against an outside; and a holding wall that is provided to the valve member, wherein the drainpipe is inserted into the drain hole so that an upper end of the drainpipe contacts the valve member to displace the valve member in a direction in which the drain hole is unblocked, fluid inside of the main body flows into the drainpipe through a drain passage defined in a portion of the drainpipe between the pipe side rib and an upper end of the drainpipe by insertion of the drainpipe, the holding wall supports the upper end of the drainpipe that is inserted into the drain hole, the drainpipe has a hooking portion that protrudes outwardly in a radial direction of the drainpipe, the cap has a protrusion that protrudes inwardly in a radial direction of the cap, the hooking portion of the drainpipe engages the protrusion of the cap when the drainpipe is inserted into the drain hole, and the holding wall makes contact with at least an inner circumferential periphery of the drainpipe when the drainpipe is inserted into the drain hole.