SPACE-CONSTRAINED HYBRID LINEAR ACTUATOR

• US 20200132209A1
• Filed: 10/26/2018
• Published: 04/30/2020
• Est. Priority Date: 10/26/2018
• Status: Active Grant

• Current Assignee: Elrich Engineering LLC
• Original Assignee: Elrich Engineering LLC
• Inventors: Orino, D. Christopher
• Granted Patent: US 10,935,053 B2
• Time in Patent Office: Days
• CPC Class Codes: F15B 1/022 used as an emergency power source, e.g. in case of pump failure
• CPC Class Codes: F15B 1/033 with electrical control means
• CPC Class Codes: F15B 15/088 the motor using combined actuation, e.g. electric and fluid actuation
• CPC Class Codes: F15B 15/18 Combined units comprising both motor and pump
• CPC Class Codes: F15B 20/002 Electrical failure
• CPC Class Codes: F15B 20/004 Fluid pressure supply failure
• CPC Class Codes: F15B 2015/1495 with screw mechanism attached to the piston
• CPC Class Codes: F15B 2015/206 Combined actuation, e.g. electric and fluid actuated
• CPC Class Codes: F15B 2211/205 Systems with pumps
• CPC Class Codes: F15B 2211/212 the pressure sources being accumulators
• CPC Class Codes: F15B 2211/625 Accumulators
• CPC Class Codes: F15B 2211/8623 Electric supply failure
• CPC Class Codes: F15B 2211/863 the abnormal condition being a hydraulic or pneumatic failure
• CPC Class Codes: F15B 2211/8757 using redundant components or assemblies
• CPC Class Codes: F16K 31/04 using a motor
• CPC Class Codes: F16K 31/122 the fluid acting on a piston F16K31/143, F16K31/163, F16K31/363, F16K31/383 take precedence
• CPC Class Codes: F16K 31/508 the actuating element being rotatable, non-rising, and driving a non-rotatable axially-sliding element
• CPC Class Codes: F16K 31/53 with toothed gearing

Abstract

An electric motor-driven, rolling element screw linear actuator is presented which work in cooperation with an hydraulic actuator and share several components. This is achieved through the integration of a screw-driven integrated nut piston assembly. Combining the use of an electric screw driven actuator can also reduce the need for a redundant hydraulic system, resulting in the elimination of 50% of connections, valves, piping, pumps, filters etc., while still being 100% redundant. An additional advantage is that the two drive systems are technologically independent, and therefore will not both fail because of an identical component flaw or failure point. The systems may also be used at the same time if conditions require force in excess of that generated by the hydraulic actuator alone.

Claims

1. An hybrid linear actuator comprising:

a first drive assembly comprising;

an electric drive motor having an output shaft;

a drive screw attached to the output shaft;

a drive nut threaded to the drive screw; and

an output rod having two ends, a first end attached to the drive nut so that rotation of the drive screw advances or retracts the output rod, and the second end capable of attachment to a linear actuated valve;

a second drive assembly comprising;

an hydraulic cylinder,

a piston disposed in the hydraulic cylinder and linked to the output rod, and

a hydraulic pump fluidly connected to the hydraulic cylinder and operable to selectively pressurize the hydraulic cylinder on either side of the piston to thereby vary a position of the piston within the hydraulic cylinder to thereby extend and retract the output rod;

wherein the drive screw is disposed at least partially within the hydraulic cylinder and is of unitary construction.

2. The linear actuator of claim 1, wherein the piston within the hydraulic cylinder is operable to rotate the drive screw.

3. The linear actuator of claim 1, further comprising a decoupling mechanism interposed between the drive screw and the output shaft of the electric drive motor, said decoupling mechanism operable to selectively couple and decouple the drive screw and the output shaft.

4. The linear actuator of claim 1, wherein the drive screw and the output rod are coaxial.

5. The linear actuator of claim 1, wherein the output rod comprises a hollow interior, and wherein the drive screw extends into the hollow interior of the output rod.

6. The linear actuator of claim 1, wherein the drive nut is disposed in the hollow interior of the output rod.

7. The linear actuator of claim 1, wherein the actuator has a third drive assembly comprising an hydraulic accumulator fluidly connected to the hydraulic cylinder and operable to selectively pressurize the hydraulic cylinder on at least one side of the piston.

8. A compact hybrid linear actuator comprising:

an hydraulic cylinder having an inner chamber, a proximal end and a distal end;

an output rod extending from the distal end the hydraulic cylinder, the output rod having a proximal end and a distal end;

a piston on the proximal end of the output rod, the piston being disposed within the inner chamber of the hydraulic cylinder;

the piston dividing the inner chamber of the hydraulic cylinder into a first pressure chamber and a second pressure chamber;

a threaded bore disposed in the first pressure chamber of the hydraulic cylinder;

the threaded bore disposed in a fixed, non-rotatable relationship with respect to the output rod; and

a drive screw disposed in the first pressure chamber and installed into the threaded bore such that rotation of the drive screw moves the output rod.

9. The linear actuator of claim 8, wherein the output rod further comprises a hollow interior, wherein a distal end of the drive screw extends into the hollow interior of the output rod.

10. The linear actuator of claim 8, wherein a proximal end of the drive screw extends from the proximal end of the hydraulic cylinder.

11. The linear actuator of claim 8, further comprising an electric motor having an output shaft linked to the proximal end of the drive screw by a drive system.

12. The linear actuator of claim 8, wherein the drive system comprises one of a belt, chain, and gear.

13. The linear actuator of claim 8, wherein the drive system comprises a decoupling mechanism operable to selectively couple and decouple the output shaft and the drive screw.

14. The linear actuator of claim 8, further comprising:

a first valve fluidly connected to the first chamber, the first valve being operable between an open position and a closed position;

a second valve fluidly connected to the second chamber, the second valve being operable between an open position and a closed position.

15. The linear actuator of claim 14, further comprising a hydraulic pump fluidly connected to the first valve and the second valve.

16. A linear actuator having redundant power sources for use in space constrained areas comprising:

an output rod having a proximal end and a distal end;

the output rod having a hollow passage way extending from its proximal end toward its distal end;

a first drive assembly comprising;

a drive nut disposed in a non-rotatable and fixed position with respect to the output rod,

a drive screw installed into the drive nut such that the drive screw extends into the hollow passage way of the output rod, and

an electric drive motor having an output shaft linked to the drive screw such that rotation of the output shaft rotates the drive screw to thereby extend and retract the output rod;

a second drive assembly comprising;

a hydraulic cylinder,

a piston disposed in the hydraulic cylinder and linked to the output rod, and

an hydraulic pump fluidly connected to the hydraulic cylinder and operable to selectively pressurize the hydraulic cylinder on either side of the piston to thereby vary a position of the piston within the hydraulic cylinder to thereby extend and retract the output rod.

17. A compact hybrid linear actuator comprising:

an output rod;

a first drive assembly comprising;

a drive nut linked to the output rod,

a drive screw installed into the drive nut,

an electric drive motor having an output shaft linked to the drive screw such that rotation of the output shaft rotates the drive screw to thereby extend and retract the output rod, and

a second drive assembly comprising;

an hydraulic cylinder,

a piston disposed in the hydraulic cylinder and linked to the output rod, and

an hydraulic pump fluidly connected to the hydraulic cylinder and operable to selectively pressurize the hydraulic cylinder on either side of the piston to thereby vary a position of the piston within the hydraulic cylinder to thereby extend and retract the output rod,

wherein the first drive assembly and the second drive assembly are individually capable of extending and retracting the output rod if the other drive assembly fails; and

wherein the output rod comprises a hollow interior, and wherein the drive screw extends into the hollow interior of the output rod.

18. A compact hybrid linear actuator as recited in claim 17, wherein the hydraulic fluid and the driving screw are in the same housing.

19. A compact linear actuator as recited in claim 17, wherein the first drive assembly and the second drive assembly may be operated at the same time to increase the thrust on the output rod.

20. A compact linear actuator as recited in claim 17, wherein when the second drive assembly is used to create a thrust force to move the piston during either extension or retraction of the rod, the thrust force generated by the hydraulic pressure against the piston is allowed to passively back drive the screw in the first drive assembly.