Compact actuator with hydraulic seal

A seal assembly for use in sealing a void between a hollow first member having a cylindrical inner surface and an annular groove in its inner surface axially defined by a first shoulder and a second shoulder, and a cylindrical second member coaxially disposed at least in part within and moveable relative to the first member, the second member having an outer surface radially spaced from the first member inner surface, the seal assembly comprising:

• an annular seal member comprising PTFE resin and having an inner edge and an outer edge, the outer edge adapted to be disposed in the groove in the first member so that the outer edge surface of the seal member contacts the first member, and the inner edge surface contacts the second member outer surface, placing the first and second members in tight sealing contact;
• an annular first backing ring adapted to be disposed substantially in the groove and between the seal member and the first shoulder;
• an annular second backing ring adapted to be disposed substantially in the groove and between the seal member and the second shoulder, and
• an annular compression spring adapted to be disposed substantially in the groove and between the first backing ring and the first shoulder,
• wherein the second member's axial alignment can differ over a range of angles from that of the first member while allowing movement of the second member and the spring exerts force axially between the shoulders to compress the seal member, impelling the seal member to increase in dimension radially and maintain the tight sealing contact between the respective inner and outer surfaces of the first and second members.

A hydraulic actuator, comprising:

• a hollow cylinder having a longitudinal axis, an inner surface, and two ends;
• a piston movably disposed in the cylinder, the piston having a longitudinal axis, two ends, an outer surface, and an annular peripheral groove approximately at the midpoint along the axis, the groove being axially defined by a first shoulder
• and a second shoulder at each edge of the groove, and the piston is tapered inwardly towards each end from each respective shoulder, such that the diameter of the piston at each shoulder is greater than the diameter at each respective end of the piston;
• a seal assembly disposed in the annular groove of the piston for placing the piston in tight sealing contact with the inner surface of the cylinder, the seal assembly comprising:
• an annular seal member comprising PTFE resin and having an inner edge and an outer edge, the seal member adapted to be disposed in the groove in the piston so that the inner edge surface of the seal member contacts the piston, and the outer edge surface contacts the inner surface of the cylinder, placing the piston and cylinder in tight sealing contact;
• an annular first backing ring adapted to be disposed substantially in the groove and between the seal member and the first shoulder;
• an annular second backing ring adapted to be disposed substantially in the groove and between the seal member and the second shoulder;
• and
• an annular compression spring adapted to be disposed substantially in the groove and between the first backing ring and the first shoulder;
• and
• a piston rod assembly having a first end and a second end, the first end of the piston rod assembly connected to the piston and the second end of the piston rod assembly extending outwardly of an end of the cylinders,
• wherein the piston's axial alignment can differ over a range of angles from that of the cylinder while allowing movement of the piston and maintaining the tight sealing contact between the piston and the cylinder inner surface, and
• wherein the spring exerts force axially between the shoulders to compress the seal member, impelling the seal member to increase in dimension radially and maintain the tight sealing contact between the respective inner and outer surfaces of the piston and cylinder.

A hydraulic actuator, comprising:

• a hollow casing having a longitudinal axis, an inner surface having a circular shape where the inner surface intersects any plane perpendicular to the axis, two ends, and an annular groove in the inner surface approximately at the midpoint along the cylinder's axis and axially defined by a first shoulder and a second shoulder at each edge of the groove, and the casing is tapered inwardly towards each shoulder from each respective end, such that the diameter of the casing at each shoulder is less than the diameter at each respective end of the casing;
• a cylindrical piston movably disposed in the casing and having a longitudinal axis;
• a seal assembly disposed in the annular groove of the casing for placing the inner surface of the casing in tight sealing contact with the piston, the seal assembly comprising:
• an annular seal member comprising PTFE resin and having an inner edge and an outer edge, the outer edge adapted to be disposed in the groove in the casing so that the outer edge surface of the seal member contacts the casing, and the inner edge surface contacts the piston outer surface, placing the piston and casing in tight sealing contact;
• an annular first backing ring adapted to be disposed substantially in the groove and between the seal member and the first shoulder;
• an annular second backing ring adapted to be disposed substantially in the groove and between the seal member and the second shoulder;
• and
• an annular compression spring adapted to be disposed substantially in the groove and between the first backing ring and the first shoulder;
• and
• a piston rod assembly having a first end and a second end, the first end of the piston rod assembly connected to the piston and the second end of the piston rod assembly extending outwardly of an end of the casing,
• wherein the piston's axial alignment can differ over a range of angles from that of the casing while allowing movement of the piston and maintaining the tight sealing contact between the piston and the casing;
• and
• wherein the spring exerts force axially between the shoulders to compress the seal member, impelling the seal member to increase in dimension radially and maintain the tight sealing contact between the respective inner and outer surfaces of the piston and casing.

An active mount for mounting a vibrating component to a support structure for use in a system for reducing vibration transmission from the vibrating component to the support structure, the active mount comprising:

• a housing adapted to be attached to one of the vibrating component or the support structure;
• and
• a hydraulic actuator disposed in the housing, the actuator comprising:
• a hollow cylinder having an inner surface;
• a piston movably disposed at least in part within the cylinder, the piston having an outer surface and an annular peripheral groove axially defined by a first shoulder and a second shoulder;
• a piston rod assembly having a first end and a second end, the first end of the piston rod assembly connected to the piston, and the second end of the piston rod assembly extending outwardly of an end of the cylinder and adapted to be attached to the other one of the vibrating component or the support structure;
• an annular seal member comprising PTFE resin and having an inner edge and an outer edge, the seal member adapted to be disposed in the groove in the piston so that the inner edge surface of the seal member contacts the piston, and the outer edge surface contacts the inner surface of the cylinder, placing the piston and cylinder in tight sealing contact;
• an annular first backing ring adapted to be disposed substantially in the groove and between the seal member and the first shoulder;
• an annular second backing ring adapted to be disposed substantially in the groove and between the seal member and the second shoulder;
• and
• an annular compression spring adapted to be disposed substantially in the groove and between the first backing ring and the first shoulder,
• wherein the spring exerts force axially between the shoulders to compress the seal member, impelling the seal member to increase in dimension radially and maintain the tight sealing contact between the respective inner and outer surfaces of the piston and cylinder.

An active mount for mounting a vibrating component to a support structure for use in a system for reducing vibration transmission from the vibrating component to the support structure, the active mount comprising:

• a housing adapted to be attached to one of the vibrating component or the support structure;
• and
• a hydraulic actuator disposed in the housing, the actuator comprising:
• a hollow casing having a longitudinal axis, an inner surface having a circular shape where the inner surface intersects any plane perpendicular to the axis, two ends, and an annular groove in the inner surface approximately at the midpoint along the cylinder's axis and axially defined by a first shoulder and a second shoulder at each edge of the groove;
• a cylindrical piston movably disposed in the casing and having a longitudinal axis;
• a piston rod assembly having a first end and a second end, the first end of the piston rod assembly connected to the piston and the second end of the piston rod assembly extending outwardly of an end of the casing,
• an annular seal member comprising PTFE resin and having an inner edge and an outer edge, the outer edge adapted to be disposed in the groove in the casing so that the outer edge surface of the seal member contacts the casing, and the inner edge surface contacts the piston outer surface, placing the piston and casing in tight sealing contact;
• an annular first backing ring adapted to be disposed substantially in the groove and between the seal member and the first shoulder;
• an annular second backing ring adapted to be disposed substantially in the groove and between the seal member and the second shoulder;
• and
• an annular compression spring adapted to be disposed substantially in the groove and between the first backing ring and the first shoulder,
• wherein the spring exerts force axially between the shoulders to compress the, seal member, impelling the seal member to increase in dimension radially and maintain the tight sealing contact between the respective inner and outer surfaces of the piston and casing.

An active mount for mounting a vibrating component to a support structure for use in a system for reducing vibration transmission from the vibrating component to the support structure, the active mount comprising:

• a housing adapted to be attached to one of the vibrating component or the support structure;
• and
• a hydraulic actuator disposed in the housing, the actuator comprising:
• a hollow cylinder having a longitudinal axis, an inner surface, and two ends;
• a piston movably disposed in the cylinder, the piston having a longitudinal axis, two ends, an outer surface, and an annular peripheral groove approximately at the midpoint along the axis, the groove being axially defined by a first shoulder and a second shoulder at each edge of the groove, and the piston is tapered inwardly towards each end from each respective shoulder, such that the diameter of the piston at each shoulder is greater than the diameter at each respective end of the piston;
• a seal assembly disposed in the annular groove of the piston for placing the piston in tight sealing contact with the inner surface of the cylinder, the seal assembly comprising:
• an annular seal member comprising PTFE resin and having an inner edge and an outer edge, the seal member adapted to be disposed in the groove in the piston so that the inner edge surface of the seal member contacts the piston, and the outer edge surface contacts the inner surface of the cylinder, placing the piston and cylinder in tight sealing contact;
• an annular first backing ring adapted to be disposed substantially in the groove and between the seal member and the first shoulder;
• an annular second backing ring adapted to be disposed substantially in the groove and between the seal member and the second shoulder;
• and
• an annular compression spring adapted to be disposed substantially in the groove and between the first backing ring and the first shoulder, and
• a piston rod assembly having a first end and a second end, the first end of the piston rod assembly connected to the piston and the second end of the piston rod assembly extending outwardly of an end of the cylinder,
• wherein the piston's axial alignment can differ over a range of angles from that of the cylinder while allowing movement of the piston and maintaining the tight sealing contact between the piston and the cylinder inner surface, and
• wherein the spring exerts force axially between the shoulders to compress the seal member, impelling the seal member to increase in dimension radially and maintain the tight sealing contact between the respective inner and outer surfaces of the piston and cylinder.

An active mount for mounting a vibrating component to a support structure for use in a system for reducing vibration transmission from the vibrating component to the support structure, the active mount comprising:

• a housing adapted to be attached to one of the vibrating component or the support structure;
• and
• a hydraulic actuator disposed in the housing, the actuator comprising:
• a hollow casing having a longitudinal axis, an inner surface having a circular shape where the inner surface intersects any plane perpendicular to the axis, two ends, and an annular groove in the inner surface approximately at the midpoint along the cylinder's axis and axially defined by a first shoulder and a second shoulder at each edge of the groove, and
• the casing is tapered inwardly towards each shoulder from each respective end, such that the diameter of the casing at each shoulder is less than the diameter at each respective end of the casing;
• a cylindrical piston movably disposed in the casing and having a longitudinal axis;
• a seal assembly disposed in the annular groove of the casing for placing the inner surface of the casing in tight sealing contact with the piston, the seal assembly comprising:
• an annular seal member comprising PTFE resin and having an inner edge and an outer edge, the outer edge adapted to be disposed in the groove in the casing so that the outer edge surface of the seal member contacts the casing, and the inner edge surface contacts the piston outer surface, placing the piston and casing in tight sealing contact;
• an annular first backing ring adapted to be disposed substantially in the groove and between the seal member and the first shoulder;
• an annular second backing ring adapted to be disposed substantially in the groove and between the seal member and the second shoulder;
• and
• an annular compression spring adapted to be disposed substantially in the groove and between the first backing ring and the first shoulder;
• and
• a piston rod assembly having a first end and a second end, the first end of the piston rod assembly connected to the piston and the second end of the piston rod assembly extending outwardly of an end of the casing,
• wherein the piston's axial alignment can differ over a range of angles from that of the casing while allowing movement of the piston and maintaining the tight sealing contact between the piston and the casing, and
• wherein the spring exerts force axially between the shoulders to compress the seal member, impelling the seal member to increase in dimension radially and maintain the tight sealing contact between the respective inner and outer surfaces of the piston and casing.

An active mount for mounting a transmission gearbox to an airframe of a rotary wing aircraft, the active mount comprising:

• a housing adapted to be attached to one of the gearbox or the airframe;
• and
• a hydraulic actuator disposed in the housing, the actuator comprising,
• a hollow cylinder having an inner surface;
• a piston movably disposed at least in part within the cylinder, the piston having an outer surface and an annular peripheral groove axially defined by a first shoulder and a second shoulder;
• a piston rod assembly having a first end and a second end, the first end of the piston rod assembly connected to the piston, and the second end of the piston rod assembly extending outwardly of an end of the cylinder and adapted to be attached to the other one of the vibrating component or the support structure;
• an annular seal member comprising PTFE resin and having an inner edge and an outer edge, the seal member adapted to be disposed in the groove in the piston so that the, inner edge surface of the seal member contacts the piston, and the outer edge surface contacts the inner surface of the cylinder, placing the piston and cylinder in tight sealing contact;
• an annular first backing ring adapted to be disposed substantially in the groove and between the seal member and the first shoulder;
• an annular second backing ring adapted to be disposed substantially in the groove and between the seal member and the second shoulder;
• and
• an annular compression spring adapted to be disposed substantially in the groove and between the first backing ring and the first shoulder,
• wherein the spring exerts force axially between the shoulders to compress the seal member, impelling the seal member to increase in dimension radially and maintain the tight sealing contact between the respective inner and outer surfaces of the piston and cylinder.