A mechanical seal assembly has rotational and stationary sealing members) and a drive unit, which is axially adjacent one of the sealing members. An energizing member urges the drive unit towards the sealing members. A retainer axially and radially retains one of the sealing members. The drive unit is in contact with one of the rotational and stationary members by way of contacting surfaces which are in the range of 1 and 20 light bands of flatness, inclusive.

A non-collapsible flexible sealing membrane (or bellows) for incorporation in a mechanical seal assembly and use in rotary shaft equipment. The sealing membrane includes a substantially radially outward extending first flange portion, which can be urged into an axially shiftable ring by a biasing mechanism. The sealing membrane further includes a substantially axially outboard extending second coaxial portion, substantially radially inward of the balance diameter of the seal. The horizontal portion is advantageously held fixed to a stub sleeve by an annular band. The angle between the vertical portion and the horizontal portion of sealing membrane enables directional control of the forces acting on stub sleeve and primary ring.

A mechanical seal in which a rotary ring can be more reliably positioned. A rotary ring unit 100 includes: a sleeve 120 fixed to a rotary shaft 500; and a rotary ring 110 of which a movement in an axial direction and a rotation with respect to the sleeve 120 is restricted, a fixed ring unit 200 includes: a fixed ring 210 configured to slide on an end surface of the rotary ring 110; and a bellows 250 which presses the fixed ring 210 toward the rotary ring 110, and the sleeve 120 is provided with a stopper 140 which restricts a movement of the rotary ring 110 toward the fixed ring 210.

A mechanical seal capable of eliminating the need for an elastic body includes a metallic sleeve 120 fixed to a rotary shaft 500 and a metallic rotary ring 110 fixed to the sleeve 120. A metallic cartridge 220 is fixed to a housing 600. A metallic fixed ring 210 is configured to slide on an end surface of the rotary ring 110. A metallic bellows 230 presses the fixed ring 210 toward the rotary ring 110, wherein the rotary ring 110 and the sleeve 120 are connected to each other by an annular first connecting part, whereby a radially inner side region and a radially outer side region are separated from each other, one end of the bellows 230 and the fixed ring 210 are connected to each other by an annular second connecting part.

A mechanical sealing device according to an embodiment of the present invention includes: a sealing ring (13) attached to a protrusion (11a) protruding from a housing (11); a mating ring (23) attached to an end portion of a rotary shaft (21); a welded bellows provided around the protrusion (11a) and located between the housing (11) and the sealing ring (13). The welded bellows (15) presses the sealing ring (13) in an axial direction to cause the sealing ring (13) to be in contact with the mating ring (23), thereby ensuring high pressure force, and in particular, uniform pressure force along its entire circumference, so as to achieve high liquid tightness, while maintaining the sizes in axial and radial directions small. Furthermore, the welded bellows (15) works as a sealing member of blocking a liquid leaked out through the O-ring (14), thereby achieving assured liquid tightness. Accordingly, an outside-type mechanical sealing device can be provided which has a compact size, and is capable of ensuring high liquid tightness in response to a high rotation speed and a high liquid pressure.

The invention relates to a mechanical seal arrangement, comprising a rotating slide ring (2) and an stationary slide ring (3), which delimit a sealing gap (4) in between them, wherein the rotating slide ring (2) has a radially inward facing ledge (20) with a contact surface (21), a bellows element (10) for refitting the rotating slide ring (2) in an axial direction (X-X) of the mechanical seal arrangement, and a release protection device (5) for the rotating slide ring (2), wherein the release protection device (5) comprises an inner sleeve (6) with a radially outward facing web (60) that restricts a movement of the rotating slide ring (2) in the axial direction (X-X), and wherein the rotating slide ring (2) is arranged on the inner sleeve (6) so as to be freely movable in the axial direction (X-X).

A secondary seal of a mechanical seal comprises an annular sealing gasket and backing plate surrounding a cylindrical sealing surface, all of which can be made of the same metallic material. The gasket is C-shaped in cross section, and is axially pressed during operation into a C-shaped groove formed in the backing plate, the groove being shallower and larger in inner diameter than the gasket, so that the gasket, when pressed into the groove, deforms radially inward and seals against both the backing plate and the sealing surface. The contact area between the gasket and sealing surface increases with pressure. In embodiments, when the pressure is released, the gasket retracts from the sealing surface, allowing easy disassembly and allowing axial movement of the gasket and backing plate. Highly polished surfaces of the gasket and sealing surface can allow axial motion thereof during operation to maintain the seal face gap.

A secondary seal of a mechanical seal comprises an annular sealing gasket and backing plate surrounding a cylindrical sealing surface, all of which can be made of the same metallic material. The gasket is C-shaped in cross section, and is axially pressed during operation into a C-shaped groove formed in the backing plate, the groove being shallower and larger in inner diameter than the gasket, so that the gasket, when pressed into the groove, deforms radially inward and seals against both the backing plate and the sealing surface. The contact area between the gasket and sealing surface increases with pressure. In embodiments, when the pressure is released, the gasket retracts from the sealing surface, allowing easy disassembly and allowing axial movement of the gasket and backing plate. Highly polished surfaces of the gasket and sealing surface can allow axial motion thereof during operation to maintain the seal face gap.

In an exemplary embodiment, a mechanical seal for sealing a fluid flowing outwardly radially from sliding surfaces S where a stationary ring 221 and a rotating ring 211 slide against each other, includes: a bellows 222 interposed between the stationary ring 221 and a stationary wall 226; a case member 223 for holding an outer cylindrical part 222c of the bellows 222 to the stationary ring 221; and a holding member 224 fitted to an inner cylindrical part 222a of the bellows 222, and having an axial length substantially equal to a length fitted to the inner cylindrical part 222a, wherein the bellows 222 has a curved part 222b between the outer cylindrical part 222c and the inner cylindrical part 222a, and the case member 223 is provided with a wall part 223a covering the entire periphery of the radial outer side of the curved part 222b.

A mechanical seal includes a housing through which a rotary shaft of a rotary machine is inserted, a stationary sealing ring held on the housing, a rotary sealing ring that is rotatable together with the rotary shaft and comes into sliding contact with the stationary sealing ring, a spring configured to axially urge the stationary sealing ring and the rotary sealing ring to a pressurized state, and a spring cover formed into an annular shape, covering the spring in an axially sealed manner on an outer diameter side or an inner diameter side and having an annular elastic body formed in an elastically deformable manner.