Patent ID: 9644745
Date: 2017-05-09
CPC Classifications: F16J

Claim:
1. A mechanical seal for sealing an annular gap between a rotating shaft and a housing, comprising: a stationary ring provided on a housing side; a rotating ring that is disposed on a sealed fluid side with respect to the stationary ring and rotates together with the rotating shaft; a pressing member that presses the rotating ring toward the stationary ring; and a sleeve fixed to the rotating shaft, wherein the sleeve has: a first annular portion that has a step having an inner diameter and an outer diameter on a sealed fluid side thereof that are larger than those of on an opposite side to the sealed fluid side thereof; an enlarged diameter portion that enlarges in diameter from an end portion of the first annular portion on the sealed fluid side toward a radially outer side; and a second annular portion that extends from an end portion of the enlarged diameter portion on a radially outer side thereof toward the opposite side, an inner peripheral surface of a small diameter portion on the opposite side with respect to the step on the first annular portion is fitted on an outer peripheral surface of the rotating shaft, and the stationary ring is disposed on an outer peripheral surface side of the small diameter portion, the rotating ring is disposed in a state in which an annular gap between an outer peripheral surface of a large diameter portion on the sealed fluid side with respect to the step on the first annular portion and an inner peripheral surface of the rotating ring is sealed, a space surrounded by the large diameter portion, the enlarged diameter portion, and the second annular portion is configured such that a sealed fluid flows therein, and the pressing member is disposed in the space, and S2÷S1≦1 is satisfied where S1 is a sliding area between the stationary ring and the rotating ring, S2 is a pressure receiving area where the stationary ring receives a pressure effect of the rotating ring due to a pressure of the sealed fluid; and wherein the rotating shaft includes a small diameter portion on which the sleeve is disposed and a large diameter portion disposed on a side further toward the sealed fluid from the small diameter portion, and the sleeve is disposed such that the enlarged diameter portion comes into intimate contact with a step portion of the rotating shaft, and the enlarged diameter portion is provided with a rotation locking portion that is formed by bending a part of the enlarged diameter portion toward the sealed fluid side at bending line, the part being formed by cutting the enlarged diameter portion along a line joining both ends of the bending line, and locks the sleeve by being fitted into a notch formed on the large diameter portion of the rotating shaft.