Linear actuator

Patent metadata

Field	Value
Publication number	US-11359704-B2
Application number	US-201815949142-A
Country	US
Kind code	B2
Filing date	Apr 10, 2018
Priority date	Apr 12, 2017
Publication date	Jun 14, 2022
Grant date	Jun 14, 2022

Abstract

A linear actuator includes: a screw shaft that has a screw thread and a longitudinal axis A and a nut movable along the screw shaft from a retracted position to an extended position. The actuator also includes a plurality of rollers movable with the nut, each of which 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 includes one or more detents (e.g., grooves) configured to lock the nut in one or more axial positions.

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 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.

2. The power door operating system of claim 1 , wherein the one or more detents are configured to prevent said compressive force from moving the nut along the screw shaft when the nut is in said one or more axial positions.

3. The power door operating system of claim 1 , wherein each of the one or more detents is provided in the form of one or more grooves configured to receive one of the plurality of rollers.

4. The power door operating system of claim 3 , wherein each of the one or more grooves has a profile that prevents a respective roller from rolling back onto the screw thread upon application of the compressive force to the nut in the axial direction.

5. The power door operating system of claim 3 , wherein each of the one or more grooves is shaped such that, upon application of the compressive force to the nut in the axial direction, a respective roller is pressed against a surface of each groove and is prevented from rolling back onto the screw thread.

6. The power door operating system of claim 3 , wherein in order to move one or more of the rollers out of the one or more grooves and back onto the screw thread against the action of the compressive force, it is necessary to rotate the screw shaft.

7. The power door operating system of claim 3 , wherein each of the one or more grooves has a shape substantially corresponding to a profile of a respective roller.

8. The power door operating system as claimed in claim 7 , wherein each of the one or more grooves has a profile corresponding to the cylindrical surface of a respective roller.

9. The power door operating system of claim 8 , wherein each of the one or more grooves has a curvature corresponding to a curvature of the cylindrical surface of a respective roller, such that when the roller falls into the groove in use, the cylindrical surface is flush with the surface of the groove.

10. The power door operating system of claim 1 , wherein the linear actuator further includes: a motor configured to rotate the screw shaft in a first rotational direction to move the nut to its extended position, and in a second rotational direction to move the nut to its retracted position, wherein:
the first rotational direction is opposite to the second rotational direction;
the motor is configured to rotate the screw shaft in the first rotational direction in order to move the rollers out of a respective groove and move the nut further in an actuation direction; and
the motor is configured to rotate the screw shaft in the second rotational direction in order to move the rollers out of a respective groove and retract the nut.

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

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

13. 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.

14. 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.

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

Assignees

• Goodrich Actuation Systems Ltd

Inventors

• Davies Stephen

Classifications

• F16H25/2261 Primary

  arranged substantially perpendicular to the screw shaft axis · 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

• B64C9/36

  the members being fuselages or nacelles · CPC title

• F16H25/2247 Primary

  with rollers · CPC title