Hydraulic actuator

A hydraulic actuator, comprising:

• a cylinder;
• a piston movably disposed in the cylinder;
• a piston rod having a first end and a second end and an outside diameter, the first end of the piston rod connected to the piston and the second end of the piston rod extending outwardly of an end of the cylinder;
• a seal member formed of a material impervious to hydraulic fluid and having an inner edge and an outer peripheral edge, the inner edge defining a central opening which is larger than the outside diameter of the rod for receiving the rod, and
• means for sealing the inner and outer edges of the seal member so that the inner edge of the seal member is radially spaced from the outside diameter of the piston rod and the seal member forms a fluid impervious wall.

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 cylinder,
• a piston movably disposed in the cylinder,
• a piston rod having a first end and a second end and an outside diameter, the first end of the piston rod connected to the piston and the second end of the piston rod extending outwardly of an end of the cylinder and connected to the other of the vibrating component or the support structure,
• a seal member formed of a material impervious to hydraulic fluid and having an inner edge and an outer peripheral edge, the inner edge defining a central opening which is larger than the outside diameter of the rod for receiving the rod, and
• means for sealing the inner and outer edges of the seal member so that the inner edge of the seal member is radially spaced from the outside diameter of the piston rod and the seal member forms a fluid impervious wall.

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 cylinder,
• a piston movably disposed in the cylinder,
• a piston rod having a first end and a second end and an outside diameter, the first end of the piston rod connected to the piston and the second end of the piston rod extending outwardly of an end of the cylinder and connected to the other of the gearbox or the airframe,
• a seal member formed of a material impervious to hydraulic fluid and having an inner edge and an outer peripheral edge, the inner edge defining a central opening which is larger than the outside diameter of the rod for receiving the rod, and
• means for sealing the inner and outer edges of the seal member so that the inner edge of the seal member is radially spaced from the outside diameter of the piston rod and the seal member forms a fluid impervious wall.

A hydraulic actuator for an active vibration and noise control system in an aircraft, the actuator for attaching to a vibrating component within the aircraft, the control system adapted to actuate the actuator to isolate vibratory load transmissions, the actuator comprising:

• a housing for mounting to the aircraft, the housing having a recess formed in it;
• a mounting member for attaching to the vibratory component;
• a lap-fit piston arrangement attached to the housing, the lap-fit piston arrangement including a piston slidably disposed within the housing;
• a bearing assembly engaged with the mounting member and the piston, the bearing assembly adapted to transmit axial motions between the mounting member and the piston, the bearing assembly also adapted to isolate moment and shear loads from the mounting member to the housing, and adapted to permit rotational movement of the inner bearing member relative to the piston, the bearing assembly comprising,
• an inner bearing member,
• a first bearing having a central axis, the first bearing located between the mounting member and the inner bearing member, the first bearing transmitting the axial motions between the mounting member and the piston,
• a second bearing having a central axis, the second bearing located between the inner bearing member and the housing, the second bearing transmitting the moment and shear loads from the mounting member to the housing, and
• a third bearing having a central axis, the third bearing located between the inner bearing member and the piston, the third bearing permitting the rotational movement of the inner bearing member relative to the piston,
• wherein the bearings are located so that the central axes are substantially aligned.

A hydraulic actuator for use in an active control system for controlling transmission of loads from a gearbox foot to an aircraft airframe of a rotary wing aircraft, the actuator comprising:

• a housing for mounting to an airframe component, the housing having a recess;
• a mounting member for attaching to a gearbox foot;
• a piston slidably disposed within the housing;
• and
• a bearing assembly engaged with the mounting member and the piston, the bearing assembly including
• an inner bearing member,
• a thrust bearing having a central axis, the thrust bearing located between the mounting member and the inner bearing member, the thrust bearing adapted to transmit axial motions between the mounting member and the piston,
• a radial journal bearing having a central axis, the radial journal bearing located between the inner bearing member and the housing, the radial journal bearing adapted to transmit moment and shear loads form the mounting member to the housing, and
• a spherical bearing having a central axis, the spherical bearing located between the inner bearing member and the piston, the spherical bearing adapted to permit limited transmission of the inner bearing member relative to the piston,
• wherein the central axes of the bearings are substantially aligned.

A hydraulic actuator in an active control system for controlling transmission of vibratory loads from a vibrating component to a support structure, the actuator comprising:

• a housing for mounting to a support structure, the housing having a recess;
• a mounting member for attaching to a component subject to vibratory loads;
• a lap-fit piston arrangement attached to the housing, the lap-fit piston arrangement including
• a piston slidably disposed within the housing, and
• a piston rod attached to the piston;
• and
• a bearing assembly attached to the mounting member and the piston rod, the bearing assembly including
• an inner bearing member,
• an elastomeric thrust bearing having a central axis, the thrust bearing located between the mounting member and the inner bearing member, the thrust bearing adapted to transmit axial motions between the mounting member and the piston,
• a radial elastomeric journal bearing having a central axis, the journal bearing located between the inner bearing member and the housing, the radial journal bearing adapted to transmit moment and shear loads from the mounting member to the housing, and
• a spherical elastomeric bearing having a central axis, the spherical bearing located between the inner bearing member and the piston, the spherical bearing adapted to permit limited rotation of the inner bearing member relative to the piston,
• wherein the central axes of the bearings are substantially aligned.