Linear actuator

Patent metadata

Field	Value
Publication number	US-11639747-B2
Application number	US-202217583669-A
Country	US
Kind code	B2
Filing date	Jan 25, 2022
Priority date	Apr 12, 2017
Publication date	May 2, 2023
Grant date	May 2, 2023

Abstract

A linear actuator includes a screw shaft comprising a screw thread and having a longitudinal axis A, a nut movable along the screw shaft from a retracted position to an extended position, and a plurality of rollers movable with the nut. Each roller includes a cylindrical surface configured to roll along one or more flanks of the screw thread, such that rotation of the screw shaft causes the rollers to roll along the flank(s) so that the nut translates in an axial direction along the screw shaft. The screw thread has a variable lead angle. The actuator can be part of a power door opening system of an aircraft.

First claim

The invention claimed is:

1. A power door operating system of an aircraft comprising:
a linear actuator, wherein the linear actuator is configured to actuate a component and includes:
a screw shaft comprising a screw thread and having a longitudinal axis (A);
a nut movable along the screw shaft from a retracted position to an extended position; and
a plurality of rollers movable with the nut, each comprising a cylindrical surface configured to roll along one or more flanks of the screw thread, such that rotation of the screw shaft causes the rollers to roll along the one or more flanks so that the nut translates in an axial direction along the screw shaft;
wherein the screw thread comprises one or more detents configured to lock the nut in one or more axial positions and the rollers rotate about a roller axis, wherein the roller axis of each of the rollers is at a non-perpendicular angle relative to the longitudinal axis of the screw shaft, the non-perpendicular angle being the same for each roller, and a compressive force exerted on the linear actuator by the component of the power door system pushes the cylindrical surface of each of the rollers against the one or more flanks, and
wherein the component of the power door operating system is configured to exert the compressive force on the linear actuator in the direction of the longitudinal axis, wherein the compressive force always acts in the direction of the longitudinal axis throughout an entire range of movement of the linear actuator, and is such that when the nut is fully retracted the compressive force is at a minimum and when the nut is fully extended the compressive force is at a maximum, and the one or more detents are configured to prevent the compressive force from retracting the nut;
wherein the rollers are all slanted in the same direction towards the longitudinal axis of the linear actuator;
wherein the screw thread has a variable lead angle.

2. The power door operating system of claim 1 , wherein the component is a door of an aircraft.

3. The power door operating system of claim 1 , wherein the component is a nacelle cowl of an aircraft.

4. The power door operating system of claim 1 , wherein the rollers are all urged against the one or more flanks of the screw thread in the same direction as the compressive force.

5. The power door operating system of claim 1 , wherein the non-perpendicular angle is defined relative to the direction of the compressive force along the longitudinal axis.

6. The power door operating system of claim 1 , wherein the rollers are slanted as such that the roller axis of each roller is tilted in the direction of the compressive force along the longitudinal axis.

7. The power door operating system of claim 1 , wherein the screw thread nearest a first end of the screw shaft has a first lead angle, the screw thread nearest a second, opposite end of the screw shaft has a second lead angle, and the first lead angle is different to the second lead angle.

8. The power door operating system of claim 7 , wherein the lead angle of the screw thread tapers gradually from the first end to the second end.

9. The power door operating system of claim 8 , wherein the lead angle of the screw thread is tailored to a particular load profile of the linear actuator.

10. A power door operating system of an aircraft comprising:
a linear actuator, wherein the linear actuator is configured to actuate a component and comprises:
a screw shaft comprising a screw thread and having a longitudinal axis (A);
a nut movable along the screw shaft from a retracted position to an extended position; and
a plurality of rollers movable with the nut, each comprising a cylindrical surface and being configured to roll along the respective flank of the screw thread, such that rotation of the screw shaft causes the rollers to roll along a respective flank so that the nut translates in an axial direction along the screw shaft, and a compressive force exerted on the linear actuator by the component of the power door system pushes the cylindrical surface of each of the rollers against the respective flank;
wherein the component of the power door operating system is configured to exert the compressive force on the linear actuator in the direction of the longitudinal axis, wherein the compressive force always acts in the direction of the longitudinal axis throughout an entire range of movement of the linear actuator, and is such that when the nut is fully retracted the compressive force is at a minimum and when the nut is fully extended the compressive force is at a maximum,
wherein the screw thread has a variable lead angle, the screw thread nearest a first end of the screw shaft has a first lead angle, the screw thread nearest a second, opposite end of the screw shaft has a second lead angle, wherein the rollers roll along the first end of the screw shaft when the nut is in the retracted position and the rollers roll along the second end of the screw shaft when the nut is in the extended position, and the first lead angle is larger than the second lead angle.

11. The linear actuator as claimed in claim 10 , wherein the lead angle of the screw thread tapers gradually from the first end to the second end.

12. The linear actuator as claimed in claim 11 , wherein the lead angle of the screw thread is tailored to a particular load profile of the linear actuator.

Assignees

• Goodrich Actuation Systems Ltd

Inventors

• Davies Stephen

Classifications

• E05F15/622

  using screw-and-nut mechanisms · CPC title

• F16H25/2261 Primary

  arranged substantially perpendicular to the screw shaft axis · CPC title

• B64C9/36

  the members being fuselages or nacelles · CPC title

• F16H25/2015

  Means specially adapted for stopping actuators in the end position; Position sensing means · CPC title

• F16H2025/228

  Screw mechanisms having rollers being supported by the screw shaft and engaging the nut · CPC title