High temperature sealing system for an axially expanding volume

A high temperature sealing system, comprising:

• an effector;
• an expandable fuel tank in the effector in which first and second cylindrical members translate axially with respect to each other at an annular metal interface upon transfer of liquid fuel into the expandable fuel tank from an external source to fill and pressurize the expandable fuel tank and to extend the length of the effector;
• a piston seal positioned in a groove around the annular metal interface to prevent fluid from leaking out between the first and second cylindrical members, said piston seal formed of a polymer, rubber or polytetrafluoroethylene (PTFE) material having a temperature rating no greater than 600° F.;
• a primary backup seal including a pair of opposing wedge-shaped rings positioned in the groove forward of the piston seal, wherein pressure in the expandable fuel tank exerted on the piston seal produces a force that drives the pair of opposing wedge-shaped rings axially together against a wedge angle, which drives the pair of wedge-shaped rings radially apart to close a gap across the annular metal interface,
• wherein during flight aerodynamic heating of the effector produces operating temperatures that exceed the temperature rating of the piston seal causing the piston seal to liquify,
• wherein the radially expanded pair of wedge-shaped rings generate a torturous flow path that resists the flow of liquified material,
• a stop that provides an end of travel (EOT) of the axial translation;
• and
• a secondary backup seal including a metal face seal positioned at the stop to prevent the flow of liquified material and fluid from leaking out.

A high temperature sealing system, comprising:

• an expandable fuel tank in which a piston translates axially with respect to a stationary cylinder at an annular interface upon transfer of fluid into the expandable volume from an external source;
• an effector in which expansion of the expandable fuel tank extends the length of the effector;
• a piston seal positioned in a groove around the annular interface to prevent fluid from leaking out between the first and second cylindrical members;
• a primary backup seal including a pair of opposing wedge-shaped rings positioned in the groove forward of the piston seal, wherein pressure in the expandable volume exerted on the piston seal produces a force that drives the pair of opposing wedge-shaped rings axially together against a wedge angle, which drives the pair of wedge-shaped rings radially apart to close a gap across the annular interface,
• wherein during flight aerodynamic heating of the effector produces temperatures that exceed a temperature rating of the piston seal causing the piston seal to liquify,
• wherein the radially expanded pair of wedge-shaped rings generate a torturous flow path that resists the flow of liquified material,
• a stop that provides an end of travel (EOT) of the axial translation;
• a secondary backup seal including metal face seal positioned at the stop to prevent the flow of liquified material and fluid from leaking out,
• a plurality of glide seals spaced along the annular interface to separate the first and second cylindrical members.

A method of high temperature sealing of a system including an expandable volume in which first and second cylindrical members translate axially with respect to each other at an annular interface upon transfer of fluid into the expandable volume from an external source and a piston seal positioned in a groove around the annular interface to prevent fluid from leaking out between the first and second cylindrical members, wherein the expandable volume is rated for operating temperatures that exceed a temperature rating of the piston seal at which the piston seal begins to liquify, the method comprising:

• positioning a primary backup seal including a pair of opposing wedge-shaped rings in the groove forward of the piston seal and a secondary backup seal including a metal face seal at a stop that provides an end of travel (EOT) of the axial translation;
• transferring fluid into the expandable volume to fill and pressurize the expandable volume, which exerts a pressure on the piston seal producing a force that drives the pair of opposing wedge-shaped rings axially together against a wedge angle, which drives the pair of wedge-shaped rings radially apart to close a gap across the annular interface generating a torturous flow path;
• at an extended EOT position, operating at temperatures in excess of the rated temperature of the piston seal causing the piston seal to liquify;
• and
• using the torturous flow path to resist the flow of the liquified material and the secondary back up seal to prevent the flow of liquified material and fluid from leaking out of the expandable volume.