Inverted Roller Screw Bearing Layout for High-Load Compact Actuators

Solution Overview

Problem

Conventional linear actuators face challenges in achieving a balance between high load capacity, compactness, and lightweight design, particularly in applications like aircraft flaps where space and weight are critical.

Innovation Solution

The use of an inverted roller screw mechanism with a bearing system comprising grooved bearing rollers that are axially fixed and radially distributed around the rotating part, providing multiple contact points for load transfer while minimizing space and weight, and featuring equal helix angles in threadings to prevent axial movement and facilitate compact, lightweight actuators.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If conventional thrust bearings such as angular contact ball bearings are used to support the rotating part, then the bearing can handle high loads, but the space required and weight increase significantly

Engineering Contradiction:

Improveload capacityVSAvoidbearing weight

Core Design Contradiction:

ForceVSWeight of stationary object

Solution Approach 1:

The patent inverts the conventional bearing arrangement by placing the bearing rollers inside the rotating part rather than outside. This inversion allows the bearing to support high loads while significantly reducing the overall bearing size and weight, as the bearing components are integrated within the rotating part's structure.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The bearing rollers are nested within the rotating part, with the rollers positioned inside the rotating part's structure. This nesting approach allows the bearing components to be compactly arranged, reducing the bearing's external dimensions and weight while maintaining load-bearing capability.

Inventive Principle:

Principle #7Nested doll (Nesting)

2Force

If conventional thrust bearings such as angular contact ball bearings are used to support the rotating part, then the bearing can handle high loads, but the space required increases significantly

Engineering Contradiction:

Improveload capacityVSAvoidbearing space

Core Design Contradiction:

ForceVSArea of stationary object

Solution Approach 1:

The patent inverts the conventional bearing arrangement by placing the bearing rollers inside the rotating part rather than outside. This inversion allows the bearing to support high loads while significantly reducing the overall bearing size and weight, as the bearing components are integrated within the rotating part's structure.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The bearing rollers are nested within the rotating part, with the rollers positioned inside the rotating part's structure. This nesting approach allows the bearing components to be compactly arranged, reducing the bearing's external dimensions and weight while maintaining load-bearing capability.

Inventive Principle:

Principle #7Nested doll (Nesting)

3Force

If the number of bearing rollers is increased to achieve the same load capacity as angular contact ball bearings, then the load capacity is maintained, but the weight and space requirements increase

Engineering Contradiction:

Improveload capacityVSAvoidnumber of bearing rollers

Core Design Contradiction:

ForceVSQuantity of substance

Solution Approach 1:

The patent inverts the conventional bearing arrangement by placing the bearing rollers inside the rotating part rather than outside. This inversion allows the bearing to support high loads while significantly reducing the overall bearing size and weight, as the bearing components are integrated within the rotating part's structure.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The bearing rollers are positioned at specific locations within the rotating part to optimize load distribution. By strategically placing the rollers at points of maximum stress and load transfer, the bearing achieves high load capacity with fewer rollers, reducing both weight and space requirements.

Inventive Principle:

Principle #3Local quality

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This solution enables the creation of linear actuators that efficiently handle high loads with reduced space and weight requirements, making them suitable for applications in aircraft and other fields where compactness and longevity are essential.

Implementation Method 1

Upon rotation of the rotating part, in particular relative to the mounting member, the bearing rollers may roll along a surface of the rotating part in a circumferential direction

Methodology Applied

Scientific EffectRolling: Roller

Implementation Method 2

The plurality of grooved bearing rollers is axially fixed therein relative to the rotating part and the mounting member

Methodology Applied

Scientific EffectFriction: Friction

Data Source

PatentUS12044295B2Linear actuator and manufacturing method

Publication Date: 2024.07.23 EWELLIX AB

AI summary

A linear actuator includes a roller screw nut, a roller screw shaft and a plurality of planetary rollers forming an inverted roller screw mechanism. A bearing supports a rotating part of the linear actuator. The bearing includes a mounting member and a plurality of bearing rollers engaging a first bearing portion of the mounting member and a second bearing portion of the rotating part. The plurality of bearing rollers is axially fixed relative to the rotating part and the mounting member. A manufacturing method for the linear actuator is also provided.