| 摘要 |
Provided is a mechanical seal device which is suitable for use even under conditions that the pressure of fluid is frequently switched between a positive pressure and a counter pressure. The mechanical seal device is comprised of a rotary ring (137) which is provided on a rotary shaft (113) so as to rotate together with the rotary shaft (113) and which has a rotary ring-side slide surface (139) that constitutes one surface of a dynamic seal surface (173), a stationary ring assembly (52) on which a stationary ring-side slide surface (54) that slides with the rotary ring-side slide surface and constitutes the other surface of the dynamic seal surface is formed, a seal cover (22) which contains the stationary ring assembly on the inner diameter side and which supports the stationary ring assembly so as to move in the axial direction of the rotary shaft, a first O-ring (92) which is sandwiched by the seal cover and the stationary ring assembly in the radial direction of the rotary shaft to seal the first fluid, and a second O-ring (96) which is provided closer to the outside of a machine than the first O-ring and which is sandwiched by the seal cover and the stationary ring assembly in the radial direction, to seal the second fluid. A low-pressure chamber (193), which is sealed off by the first O-ring and the second O-ring from the first fluid and the second fluid and is maintained at a pressure lower than the pressure of the first fluid and the second fluid, is formed between the first O-ring and the second O-ring. A first pressure acting diameter (100) is positioned, when viewed in the radial direction, on the side of a second seal end portion (177) which corresponds to the second fluid-side end portion of the dynamic seal surface with respect to a first seal end portion (175) which corresponds to the first fluid-side end portion of the dynamic seal surface. A second pressure acting diameter is positioned, when viewed in the radial direction, on the side of the first seal end portion with respect to the second seal end portion. |
