Patent ID: 7740433

Claim:
A waterproof structure for a tightening section where a first member ( 1 ) having a screw hole ( 1 a ) with a bottom and a second member ( 2 ) having a screw insertion hole ( 2 a ) are fastened with a screw that is inserted into the screw insertion hole ( 2 a ) and screwed to the screw hole ( 1 a ), the waterproof structure preventing water from penetrating into a gap between the first member and the second member, the waterproof structure comprising: the screw being a conical screw ( 4 ) whose head has a conical shape, a spacer ( 3 ) having an insertion hole where a recessed circular conical surface ( 3 a ) is formed to be in surface contact with a circular conical surface of the head of the conical screw ( 4 ), wherein the spacer is fitted in the screw insertion hole ( 2 a ) and an annular groove ( 3 b ) is formed in the outer surface of the spacer ( 3 a ); and an O-ring ( 5 ) installed in the annular groove ( 3 b ), wherein the conical screw ( 4 ) is tightened with the spacer ( 3 ) placed between the first member ( 1 ) and the second member ( 2 ), causing the O-ring ( 5 ) to be pressed between an inner surface of the annular groove ( 3 b ) and a surface of the screw insertion hole of the second member.