EP-4735777-A1 - BELT DRIVEN LINEAR ACTUATOR COMPRISING A SELF-ALIGNMENT SYSTEM AND METHOD OF OPERATING THE SAME

Abstract

A self-aligning system within a belt-driven linear actuator that enables a "keyless" or "round profile" piston to be sealed while maintaining an aligning and/or torque resisting ability. Operating piston 204 is affixed to output shaft 106 and provides a structural member for mounting traveling sheaves from both contracting pulley system 206 and expanding pulley system 202. This enables the airspaces within the electromechanical actuator could be pressurized to perform a secondary load holding function that is redundant to the linear screw device.

Inventors

• SESSIONS, Blake

Assignees

• Liftwave Inc. Dba Rise Robotics

Dates

Publication Date

20260506

Application Date

20240624

Claims (20)

1. 1. An alignment system for a belt-driven linear actuator comprising: an actuator chassis comprising an inner surface; a traveling assembly comprising an operating piston and an output shaft and configured to translate along a primary axis defined by a centerline of the output shaft; a roller rotatably coupled to the traveling assembly and configured to mechanically engage with the inner surface of the actuator chassis, the roller having an axis of rotation that is perpendicular to the primary axis; a first flanged sheave coupled to the output shaft; a second flanged sheave coupled to the actuator chassis; and a belt extending between and around the first and second sheaves.
2. 2. The system of claim 1. wherein the roller is engaged with the inner surface by a spring, wherein the spring is pre-loaded by a set screw.
3. 3. The system of claims 1 or 2, wherein the first flanged sheave and the second flanged sheave operate as a pulley system configured to translate the output shaft along the axis.
4. 4. The system of any of claims 1-3, wherein the roller has a curved surface shaped to maximize a contact area between the roller and the inner surface.
5. 5. The system of any of claims 1-4. wherein the roller permits rotation of the output shaft about the primary axis in a range of 0.1 - 1 degrees of rotation per meter of travel.
6. 6. The system of any of claims 1-5, wherein the roller is one of a plurality of rollers, wherein the plurality of rollers form an annular arrangement that at least partially encloses the output shaft.
7. 7. A method for operating a belt-driven linear actuator comprising: translating a traveling assembly of the belt-driven linear actuator; and while translating the traveling assembly, allowing the traveling assembly to rotate about a primary’ axis to correct alignment of a belt between a first sheave and a second sheave.
8. 8. The method of claim 7, comprising: preventing rotation about the primary axis when the traveling assembly is not translating.
9. 9. The method of claim 8, wherein preventing rotation about the primary axis comprises frictionally resisting rotation using one or more members affixed to the traveling assembly and mechanically engaged with an inner surface of an actuator chassis by one or more preloaded springs.
10. 10. The method of any of claims 7-9, wherein the linear actuator comprises: an actuator chassis comprising an inner surface; and the traveling assembly comprising an operating piston and an output shaft and configured to translate along the primary axis, wherein the primary axis is defined by a centerline of the output shaft.
11. 11. The method of any of claims 7-10, wherein the linear actuator comprises: an actuator chassis comprising an inner surface; and a roller rotatably coupled to the traveling assembly and configured to mechanically engage w ith the inner surface of the actuator chassis, the roller having an axis of rotation that is perpendicular to the primary axis.
12. 12. The method of any of claims 7-11, wherein the first sheave is a flanged sheave, and is coupled to the traveling assembly, wherein the second sheave is a flanged sheave and is coupled to an actuator chassis of the linear actuator, and w herein the traveling assembly rotates about the primary axis in response to sidewall forces generated between the first and second sheaves and the belt.
13. 13. The method of any of claims 7-12, wherein allowing the traveling assembly to rotate comprises allowing the traveling assembly to rotate in the range of 0. 1 - 1 degree per meter of travel.
14. 14. The method of any of claims 7-13, wherein the first sheave and the second sheave operate as a pulley system configured to translate the traveling assembly along the primary axis.
15. 15. A system for operating a belt-driven linear actuator comprising: a pneumatically operated system comprising: a proximal volume: a distal volume; an operating piston affixed to an output shaft of the linear actuator, the operating piston separating the proximal and distal volumes; and a valve configured to direct gas to the proximal or distal volume, thereby creating a differential pressure across the operating piston; and an alignment system configured to maintain rotational alignment of the output shaft of the linear actuator, the alignment system comprising: an actuator chassis comprising an inner surface a roller rotatably coupled to a traveling assembly and configured to mechanically engage with the inner surface of the actuator chassis, the roller having an axis of rotation that is perpendicular to a primary axis defined by a centerline of the output shaft; a first flanged sheave coupled to the output shaft; a second flanged sheave coupled to the actuator chassis; and a flat belt extending between and around the first and second sheaves.
16. 16. The system of claim 15, wherein the roller is engaged with the inner surface by a spring, wherein the spring is pre-loaded by a set screw.
17. 17. The system of claims 15 or 16, wherein the first flanged sheave and the second flanged sheave operate as a pulley system configured to translate the operating piston along the primary axis.
18. 18. The system of any of claims 15-17, wherein the roller has a curved surface shaped to maximize a contact area between the roller and the inner surface.
19. 19. The system of any of claims 15-18, wherein the valve is a three-way valve that is selectable to direct gas to either the proximal or the distal volumes, the system comprising: an isolation valve configured to, when opened, initiate flow of gas; and a controller, configured to receive information associated with the operating load of the linear actuator and align the three-way valve to direct gas to oppose the operating load.
20. 20. The system of claim 19, wherein the controller is configured to adjust an amount of pressure supplied by the isolation valve to match the differential pressure across the operating piston with the operating load.

Description

BELT DRIVEN LINEAR ACTUATOR COMPRISING A SELF-ALIGNMENT SYSTEM AND METHOD OF OPERATING THE SAME TECHNICAL FIELD [0001] This disclosure generally relates to a self-aligning, belt-driven linear actuator that includes a pneumatic backup operation functionality. BACKGROUND [0002] Modem belts have many desirable characteristics. They can be lightweight, low-maintenance, and have high strength under tension. Many new and old applications of modem belts are currently being adapted. Linear actuators are often used to manipulate sensitive, heavy, or dangerous loads. Emergency hold and backup operation can be an important capability for certain applications. SUMMARY [0003] In general, the disclosure involves systems and methods for pneumatically operating and self-alignment of a belt-driven linear actuator. The alignment system can include an actuator chassis having an inner surface, a traveling assembly that includes an operating piston and an output shaft. The traveling assembly can be configured to translate along a primary axis defined by a centerline of the output shaft. A roller can be rotatably coupled to the traveling assembly and configured to mechanically engage with the inner surface of the actuator chassis, the roller including an axis of rotation that is perpendicular to the primary axis. A first flanged sheave can be coupled to the output shaft and a second flanged sheave can be coupled to the actuator chassis and a belt can extend between and around the first and second sheaves. [0004] The alignment system optionally includes one or more of the following features. [0005] In some instances, the roller is engaged with the inner surface by a spring, and the spring is pre-loaded by a set screw. [0006] In some instances, the first flanged sheave and the second flanged sheave operate as a pulley system configured to translate the output shaft along the axis. [0007] In some instances, the roller has a curved surface shaped to maximize a contact area between the roller and the inner surface. [0008] In some instances, the roller permits rotation of the output shaft and affixed components about the primary axis in a range of 0. 1 - 1 degrees of rotation per meter of travel. [0009] In some instances, the roller is one of a plurality of rollers, and the plurality of roller form an annular arrangement that at least partially encloses the output shaft. [0010] This disclosure further includes a method of operating a belt-driven linear actuator, the method including translating a traveling assembly of the belt-driven linear actuator and, while translating the traveling assembly, allowing the traveling assembly to rotate about a primary axis to maintain alignment of a belt between a first sheave and a second sheave. [0011] The method optionally includes one or more of the following features. [0012] In some instances, the method includes preventing rotation about the primary axis when the traveling assembly is not translating. This prevention can include frictionally resisting rotation using one or more members affixed to the traveling assembly and mechanically engaged with an inner surface of an actuator chassis by one or more preloaded springs. [0013] In some instances, the linear actuator includes an actuator chassis with an inner surface and the traveling assembly includes an operating piston and an output shaft that translates along the primary axis, where the primary axis is defined by a centerline of the output shaft. In some instances the linear actuator comprises a roller rotatably coupled to the traveling assembly and configured to mechanically engage with the inner surface of the actuator chassis, the roller having an axis of rotation that is perpendicular to the primary' axis. [0014] In some instances, the first sheave and the second sheave are flanged sheaves, and the first sheave is coupled to the traveling assembly and the second sheave is coupled to an actuator chassis. [0015] This disclosure further describes a pneumatically operated belt-driven linear actuator. The system includes a pneumatically operated system and an alignment system. The pneumatically operated system includes a proximal volume, a distal volume, an operating piston affixed to an output shaft of the linear actuator, the operating piston separating the proximal and distal volumes, and a valve configured to direct gas to the proximal or distal volume, thereby creating a differential pressure across the operating piston. The alignment system is configured to maintain rotational alignment of the output shaft of the linear actuator, and includes an actuator chassis having an inner surface, a roller rotatably coupled to a traveling assembly7 and configured to mechanically engage with the inner surface of the actuator chassis. The roller has an axis of rotation that is perpendicular to the primary7 axis defined by a centerline of the output shaft. The alignment system further includes a first flanged sheave coupled to the output shaft, a