Hydraulic actuator

• US 6,634,862 B2
• Filed: 09/14/2001
• Issued: 10/21/2003
• Est. Priority Date: 09/15/2000
• Status: Expired due to Fees

• Current Assignee: General Dynamics Advanced Information Systems Incorporated (General Dynamics Corporation)
• Original Assignee: General Dynamics Advanced Information Systems Incorporated (General Dynamics Corporation)
• Inventors: Terpay, Gregory Weston, Ernst, Ronald G.
• Primary Examiner(s): Look, Edward K.
• Assistant Examiner(s): McCoy, Kimya N
• Application Number:
  US09/952,525
• Publication Number:
  US 20020100650A1
• Time in Patent Office: 767 Days
• Field of Search: 416/170.R, 416/500, 921/68
• US Class Current: 416/170.00R
• CPC Class Codes: F15B 15/1471 Guiding means other than in the end cap F15B15/1466 takes precedence
• CPC Class Codes: F16F 15/023 using fluid means
• CPC Class Codes: F16F 9/36 Special sealings, including sealings or guides for piston-rods F16F9/325, F16F9/3485 take precedence; arrangements for filling via piston rod sealing or guiding means F16F9/432 ; sealing of moving parts in general F16J15/16 - F16J15/56
• CPC Class Codes: Y10S 416/50 Vibration damping features
• CPC Class Codes: Y10T 82/266 Mandrel

Abstract

A seal assembly is provided for use in a hydraulic actuator of the type including a cylinder, a piston movably disposed in the cylinder, and a piston rod connected to the piston and extending from an end of the cylinder. The seal assembly comprises a seal member formed of a material impervious to hydraulic fluid and having an inner edge and an outer peripheral edge. The inner edge of the seal member defines a central opening which is larger than the outside diameter of the piston rod for receiving the rod. The outer edges of the seal member are attached adjacent the end of the cylinder 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 for preventing hydraulic fluid from contacting the elastomeric portion of the bearing assembly.

Claims

1. A seal assembly for use in a hydraulic actuator, the actuator including a cylinder, a piston movably disposed in the cylinder, and a piston rod having first and second ends 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, the seal assembly comprising:

a seal member formed of a material impervious to hydraulic fluid and having an inner edge and an outer peripheral edge, the inner edge of the seal member 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.

2. A seal assembly as recited in claim 1, wherein the seal member material is flexible for accommodating relative movement between the piston and the cylinder.

3. 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.

4. A hydraulic actuator as recited in claim 3, wherein the seal member material is flexible for accommodating relative movement between the piston and the cylinder.

5. A hydraulic actuator as recited in claim 3, wherein the piston is a lap-fit piston.

6. A hydraulic actuator as recited in claim 3, further comprising a bearing assembly connected to the second end of the piston rod externally of the cylinder.

7. A hydraulic actuator as recited in claim 6, wherein the sealing means comprises first and second rings removably attached to the bearing assembly so that the inner and outer edges, respectively, of the seal member are sealingly secured between the rings and the bearing assembly for preventing hydraulic fluid from contacting the bearing assembly.

8. A hydraulic actuator as recited in claim 7, wherein the bearing assembly comprises elastomeric and non-elastomeric portions and the sealing rings are attached to the non-elastomeric portion of the bearing assembly for preventing hydraulic fluid from contacting the elastomeric portion of the bearing assembly.

9. 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.

10. An active mount as recited in claim 9, wherein the seal member material is flexible for accommodating relative movement between the piston and the cylinder.

11. An active mount as recited in claim 9, wherein the piston is a lap-fit piston.

12. An active mount as recited in claim 9, further comprising a bearing assembly connected between the second end of the piston rod and the other of the vibrating component or the support structure.

13. A hydraulic actuator as recited in claim 12, wherein the sealing means comprises a first and second rings removably attached to the bearing assembly so that the inner and outer edges, respectively, of the seal member are sealingly secured between the rings and the bearing assembly for preventing hydraulic fluid from contacting the bearing assembly.

14. A hydraulic actuator as recited in claim 13, wherein the bearing assembly comprises elastomeric and non-elastomeric portions and the sealing rings are attached to the non-elastomeric portion of the bearing assembly for preventing hydraulic fluid from contacting the elastomeric portion of the bearing assembly.

15. 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.

16. An active mount as recited in claim 15, wherein the seal member material is flexible for accommodating relative movement between the piston and the cylinder.

17. An active mount as recited in claim 15, wherein the piston is a lap-fit piston.

18. An active mount as recited in claim 15, further comprising a bearing assembly connected between the second end of the piston rod and the other of the gearbox or the airframe.

19. A hydraulic actuator as recited in claim 18, wherein the sealing means comprises first and second rings removably attached to the bearing assembly so that the inner and outer edges, respectively, of the seal member are sealingly secured between the rings and the bearing assembly for preventing hydraulic fluid from contacting the bearing assembly.

20. A hydraulic actuator as recited in claim 19, wherein the bearing assembly comprises elastomeric and non-elastomeric portions and the sealing rings are attached to the non-elastomeric portion of the bearing assembly for preventing hydraulic fluid from contacting the elastomeric portion of the bearing assembly.

21. 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.

22. An actuator according to claim 21 wherein the bearings are elastomeric bearings, and wherein the first bearing is a thrust bearing and the second bearing is a radial journal bearing and the third bearing is a spherical bearing.

23. An actuator according to claim 21 further comprising a piston rod attached at one end to the piston and at the other end to a bearing support, and wherein the third bearing is located between the inner bearing member and the bearing support.

24. 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.

25. A hydraulic actuator according to claim 24 further comprising a piston rod attached at one end to the piston and at the other end to a bearing support, and wherein the third bearing is located between the inner bearing member and the bearing support.

26. 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.