Ballscrew Assembly Axial Length Reduction
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Solution Overview
Problem
Conventional ballscrew assemblies in aircraft brakes are characterized by excessive axial length, which is undesirable, and often rely on roller bearings that increase friction and are prone to poor performance due to the concentration of loads on a single portion of the ballscrew.
Innovation Solution
The implementation of a ballscrew assembly with axially distributed grooves for rolling element bearings, allowing for a reduced axial length, load distribution across multiple rolling elements, and the use of ball bearings instead of rollers, along with an extended top plate and thrust bearings to eliminate the need for preloading rolling elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional ballscrew assemblies use roller bearings and preloading rolling elements, then load capacity is improved, but axial length increases and friction increases
Solution Approach 1:
The ballscrew assembly segments the load-bearing function across multiple rolling elements (balls) distributed along the axial direction. Instead of using a single preloading rolling element, the invention uses multiple balls that collectively bear the load, thereby reducing the axial length required while maintaining load capacity.
Solution Approach 2:
The invention transitions from using roller bearings (which contact along a line) to ball bearings (which contact at points). This dimensional change from line contact to point contact allows for reduced axial length while maintaining load capacity through the distribution of loads across multiple balls.
2Strength
If roller bearings are used in conventional ballscrew assemblies, then load capacity is improved, but friction increases and performance deteriorates
Solution Approach 1:
The invention replaces roller bearings with ball bearings, substituting one mechanical rolling element system with another. Balls have lower rolling resistance and friction compared to rollers, thereby reducing energy loss while maintaining load capacity through the use of multiple balls.
Solution Approach 2:
The load-bearing function is segmented across multiple ball bearings instead of using a single roller bearing. This segmentation distributes the load and reduces friction, as multiple point contacts with balls generate less friction than line contacts with rollers.
3Measurement precision
If preloading rolling elements are used in conventional ballscrew assemblies, then positioning accuracy is improved, but device complexity increases
Solution Approach 1:
The invention merges the preloading function with the load-bearing function by using the same multiple ball bearings for both purposes. Instead of having separate preloading rolling elements and load-bearing roller bearings, the multiple balls perform both functions, thereby reducing device complexity while maintaining positioning accuracy.
Solution Approach 2:
The multiple ball bearings serve multiple functions: they provide preloading for positioning accuracy, bear radial and axial loads, and reduce friction. This multi-functionality eliminates the need for separate preloading components, thereby reducing assembly complexity.
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 configuration reduces axial length, improves load handling, and reduces friction by distributing loads across a greater number of rolling elements, while eliminating the need for preloading, thus enhancing the performance and design simplicity of the ballscrew assembly.
Implementation Method 1
one or more rolling element bearings (e.g., balls or rollers) are in contact with the ballscrew and top plate
Implementation Method 2
An axially distributed thrust bearing is disposed in a space bounded by the axially distributed ballscrew groove and the axially distributed extended top plate groove
Data Source
AI summary
A ballscrew assembly may comprise a ballscrew having an axially distributed ballscrew groove about an interior circumference of the ballscrew, an extended top plate having an axially distributed extended top plate groove disposed on an outer circumference of the extended top plate, and an axially distributed thrust bearing. Further, a ballnut assembly may comprise a ballnut having an axially distributed ballnut groove about an interior circumference of the ballnut, an extended top plate having an axially distributed extended top plate groove disposed on an outer circumference of the extended top plate, and an axially distributed thrust bearing. Further still, a ballnut assembly may comprise a ballnut having an axially distributed ballnut groove about an outer circumference of the ballnut, an extended top plate having an axially distributed extended top plate groove disposed on an interior circumference of the extended top plate and an axially distributed thrust bearing.