Sealing apparatus for rotating shafts, in particular stern tube seal for the propeller shaft of a ship

A stern tube seal for a rotating propeller shaft of a ship, the propeller shaft having an axial direction, said stern tube seal comprising:

• a first seal for functioning as a main seal;
• and
• a backup seal, said backup seal comprising:
• compressible sealing means for sealing around the propeller shaft;
• a gland member for being displaced in the axial direction for compressing and decompressing said compressible sealing means, to vary sealing;
• means for guiding the displacement of said gland member in the axial direction;
• plural means for displacing said gland member in the axial direction, relative to said guiding means, for compressing and decompressing said compressible sealing means;
• each of said plural displacing means being disposed between a portion of said gland member and a portion of said guiding means;
• and
• each of said plural displacing means being configured to be activated by a pressurized medium.

The stern tube seal of claim 20, wherein the propeller shaft comprises a bushing, said stern tube seal further comprising:

• said pressure control means comprising a piston-cylinder arrangement;
• said flange-shaped extension having a recess, said recess being connected to said connecting means;
• said connecting means comprising a threaded bolt member being connected between said recess of said flange-shaped extension and said support body, said threaded bolt member being axially-parallel to the propeller shaft, and said connecting means comprising a threaded nut cooperating with said threaded bolt member and said recess, said threaded nut being for connecting said threaded bolt member to said flange-shaped extension and for moving said guide means and said gland member in an axial direction;
• said elastic restoring means connecting between said gland member and said support body;
• said elastic restoring means comprising a spring member and a tappet member, said spring member being connected with said tappet member to bias said tappet member;
• said threaded bolt member being separate from said tappet member;
• said threaded bolt member being configured for holding said guide member in a fixed relationship with respect to said support body;
• said gland member being configured for fitting into said guide member to form a greater piston-cylinder unit;
• a portion of said gland member being configured to telescope into said guide member to form said piston-cylinder unit;
• said piston-cylinder arrangement comprising a piston and a cylinder, said cylinder being divided into a first chamber and a second chamber by said piston, said first chamber being disposed towards one end of said cylinder and said second chamber being disposed towards another end of said cylinder;
• said pressure line being a main pressure line;
• said main pressure line extending from said first chamber of said piston, and communicating between said first chamber of said piston and said plurality of piston-cylinder units;
• a feeder line extending from the medium to be sealed out to said piston-cylinder arrangement, said feeder line communicating between the medium to be sealed out and said second chamber of said piston;
• said main seal comprising a rotating mechanical seal;
• said main seal further comprising:
• a seal ring for sealing out the medium to be sealed out;
• a ring connected to the bushing for rotating with the bushing;
• a clamping ring connected to said support body;
• said ring connected to the bushing and said clamping ring for bracing said seal ring therebetween, for sealing between said seal ring and each of said clamping ring and said ring connected to the bushing;
• a first seal spring for biasing said seal ring between said ring connected to the bushing and said clamping ring, said first seal spring being connected between said clamping ring and said support body;
• a first seal pin for connecting said clamping ring to said support body, said pin being configured to prevent rotation of said clamping ring and to permit movement of said clamping ring in the axial direction;
• a plurality of clamping ring seals for sealing between said clamping ring and said support body;
• said backup seal further comprising:
• said compressible sealing means comprising a plurality of soft packings;
• said soft packings being deformable in response to axial movement of said gland member;
• said soft packings for being aligned with one another, and for being disposed adjacent and against one another, along an axial direction of the propeller shaft;
• said soft packings for being disposed about the propeller shaft;
• one of said soft packings being configured for contacting said gland member;
• said soft packings being disposed within said support body;
• a plurality of branch pressure lines being connected between said main pressure line and said plurality of piston-cylinder units, each of said plurality of branch pressure lines being connected with a corresponding one of said piston-cylinder units for conducting the pressurized medium to the corresponding one of said piston-cylinder units;
• said piston-cylinder units being disposed in a circle about the propeller shaft, the circle being concentric with the propeller shaft;
• said guiding means being a guide body and being rigidly connected to said support body by means of said threaded bolt member;
• a pressure source for providing the pressurized medium to said piston-cylinder units, said pressure source being one of a hydraulic pump and a pneumatic pump;
• said gland comprising an external ring flange;
• said external ring flange comprising a plurality of cylindrical recesses;
• said plurality of cylindrical recesses of said external ring flange being eight cylindrical recesses;
• said plurality of cylindrical recesses being uniformly distributed, in a circle, about the propeller shaft;
• said guide body comprising a plurality of additional cylindrical recesses and a plurality of pistons disposed within said additional cylindrical recesses, each of said pistons being slidably disposed within a corresponding one of said additional cylindrical recesses of said guide body;
• said plurality of additional cylindrical recesses of said guide body being eight cylindrical recesses and said plurality of pistons being eight pistons;
• said piston-cylinder units comprising said cylindrical recesses of said external ring flange, said additional cylindrical recesses of said guide body and said pistons;
• each of said pistons being configured to slidably displace into a corresponding one of said cylindrical recesses of said external ring flange;
• and
• each of said pistons having a general cup shape;
• the pressurized medium being hydraulic fluid;
• a reservoir for containing the hydraulic fluid;
• check valve means for preventing the flow of hydraulic fluid towards said pressure source;
• gauge means for measuring the pressure of the hydraulic fluid;
• a second pressure line being connected to empty into the medium to be sealed out, said second pressure line being connected to said main pressure line;
• said pressure control means being disposed along said second pressure line;
• valve means for controlling the pressure of the pressurized medium in said main pressure line;
• automatic flow control means for activating the pressurized medium;
• means for sensing and draining leaks, the leaks being of the medium to be sealed out when the medium to be sealed out has penetrated the main seal, said means for sensing and draining leaks being configured for activating said automatic flow control means to increase the pressure of the pressurized medium when a predetermined maximum leakage occurs;
• an auxiliary seal for sealing around the propeller shaft, said auxiliary seal being between the medium to be sealed out and both said first seal and said backup seal;
• said auxiliary seal being configured to be activated by a pressurized medium;
• and
• said auxiliary seal being inflatable.

A method of operating a stern tube seal for a rotating propeller shaft of a ship, the propeller shaft having an axial direction, the stern tube seal comprising:

• a first seal for functioning as a main seal;
• and a backup seal, the backup seal comprising:
• compressible sealing means for sealing around the propeller shaft, a gland member for being displaced in the axial direction for compressing and decompressing the compressible sealing means to vary sealing, means for guiding the displacement of the gland member in the axial direction, plural means for displacing the gland member in the axial direction, relative to the guiding means, for compressing and decompressing said compressible sealing means, each of the plural displacing means being disposed between a portion of the gland member and a portion of the guiding means, and each of the plural displacing means being configured to be activated by a pressurized medium;
• said method comprising the steps of:
• providing a first seal for functioning as a main seal;
• providing a backup seal and, for the backup seal, providing:
• the compressible sealing means for sealing around the propeller shaft;
• the gland member for being displaced in the axial direction for compressing and decompressing the compressible sealing means to vary sealing;
• the means for guiding the displacement of the gland member in the axial direction;
• the plural means for displacing the gland member in the axial direction, relative to the guiding means, for compressing and decompressing the compressible sealing means, each of the plural displacing means being disposed between a portion of the gland member and a portion of the guiding means and each of the plural displacing means being configured to be activated by the pressurized medium;
• said method comprising the further steps of:
• sealing the propeller shaft with the first seal;
• operating the backup seal by:
• sealing the backup seal around the propeller shaft by means of the compressible sealing means;
• displacing the gland member in the axial direction for compressing and decompressing the compressible sealing means to vary sealing;
• guiding, by means of the guiding means, the displacement of the gland member in the axial direction;
• displacing, by means of the plural displacing means, the gland member in the axial direction, relative to the guiding means, for compressing and decompressing the compressible sealing means;
• disposing each of the plural displacing means between a portion of the gland member and a portion of the guiding means;
• configuring each of the plural displacing means to be activated by a pressurized medium;
• and
• activating each of the plural displacing means by means of the pressurized medium.