Planetary Roller Screw with Segmented Planet Threads
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Solution Overview
Problem
Existing planetary roller screw arrangements face inefficiencies in converting rotary motion to linear motion due to overlapping components and complex manufacturing processes, which affect reliability and cost-effectiveness.
Innovation Solution
A planetary roller screw arrangement with a threaded nut, spindle, and planets, featuring a partially threaded nut bore and continuous planet engagement, allows for efficient conversion of rotary to linear motion with simplified manufacturing and reduced component overlap, utilizing push rods for telescoping action and planet ring support.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If traditional planetary roller screw arrangements are used, then high axial forces can be generated, but the component overlap and complex manufacturing processes reduce reliability and increase cost
Solution Approach 1:
The patent divides the continuous threaded planet into multiple discrete threaded segments along the planet's length. Each segment engages with the threaded nut at different positions, allowing the planet to maintain continuous engagement while reducing overlap complexity. This segmentation enables simpler manufacturing of each segment while preserving the high axial force generation capability through distributed engagement points.
2Force
If traditional planetary roller screw arrangements are used, then high axial forces can be generated, but the component overlap and complex manufacturing processes increase manufacturing complexity
Solution Approach 1:
The threaded planet is divided into multiple discrete threaded segments, each with simplified geometry that is easier to manufacture. The segments are distributed along the planet's length and engage the threaded nut at different positions, reducing the need for complex overlapping thread patterns while maintaining force generation capability.
Solution Approach 2:
Different portions of the planet have different properties - the threaded segments have engaged portions with specific thread characteristics, while non-threaded portions have different geometric properties. This local differentiation allows optimization of each segment for its specific function, simplifying manufacturing while maintaining overall performance.
3Reliability
If the threaded planet longitudinal length is increased to improve engagement, then component overlap increases and manufacturing complexity increases
Solution Approach 1:
Instead of using a single long continuous thread on the planet, the patent uses multiple shorter threaded segments distributed along the planet's length. Each segment provides localized engagement with the threaded nut, achieving reliable engagement through distributed contact points rather than continuous overlap, thereby reducing manufacturing 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
Enhances efficiency and reduces manufacturing complexity while maintaining high axial forces and reliability, offering improved cost-effectiveness and performance in converting rotary to linear motion.
Implementation Method 1
The threaded nut includes a bore that has a first threaded portion that spans a second longitudinal length. The threaded spindle has a second threaded portion that spans a third longitudinal length. The plurality of threaded planets has a third threaded portion that threadedly engages with the first threaded portion
Data Source
AI summary
A planetary roller screw arrangement is provided includes a threaded nut, a threaded spindle, and a plurality of threaded planets. The threaded nut has a first longitudinal length and a first threaded portion that spans a second longitudinal length. The threaded spindle has a second threaded portion that spans a third longitudinal length. The plurality of threaded planets are arranged radially between the threaded spindle and the threaded nut and have a third threaded portion configured to be threadedly engaged with the first threaded portion, the third threaded portion spanning a fourth longitudinal length. The fourth longitudinal length is greater than the third longitudinal length.