Roller Screw Preload Structure With Shared Bearing Loading
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Solution Overview
Problem
Current linear actuators in the aerospace field, particularly those using roller screw mechanisms, are complex and heavy due to the need for multiple preloading components, which complicates design and manufacturing, and are prone to damage from vibrations and high vacuum conditions during launch.
Innovation Solution
A simplified linear actuator design that uses a single preloading device capable of simultaneously loading both the roller screw mechanism and its rotational guide, featuring angular contact ball bearings with threaded rings as inner rings and a metal bellows or key linkage, along with an elastic ring and clamping screws to impose stress on the outer rings, reducing the number of components and enhancing manufacturing ease.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple preloading components (support rings, coil spring, preload nuts) are used to preload the roller screw mechanism and rotational guidance separately, then the preloading function is achieved, but the device complexity and mass increase significantly
Solution Approach 1:
The invention merges the preloading functions for the roller screw mechanism and the rotational guidance bearing into a single integrated preloading device. This device simultaneously applies preload to both the threaded rings of the roller screw mechanism and the outer rings of the angular contact ball bearings, eliminating the need for separate preloading mechanisms and reducing the total number of components.
Solution Approach 2:
The preloading device is designed with multi-functionality, serving both to preload the roller screw mechanism and to preload the rotational guidance bearing. By making the preloading device universal, it performs multiple functions that previously required separate dedicated components, thereby simplifying the overall actuator structure.
2Reliability
If separate preloading devices are used for the roller screw mechanism and the rotational guidance bearing, then each mechanism is properly preloaded, but the manufacturing cost and design complexity increase
Solution Approach 1:
The invention combines two separate preloading operations into a single integrated device that can be manufactured and installed as one unit. This reduces the manufacturing steps, assembly operations, and quality control checkpoints, thereby improving ease of manufacture while maintaining proper preload application to both mechanisms.
3Reliability
If multiple stainless steel preloading components are used, then the preloading function is reliable, but the mass and volume of the linear actuator increase
Solution Approach 1:
By merging the preloading functions into a single device, the invention reduces the total mass of stainless steel components required. Instead of having multiple separate preloading components (support rings, coil springs, preload nuts for both mechanisms), the integrated device uses a unified structure that achieves the same preloading reliability with less material.
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 design simplifies the actuator's structure, reduces component count, improves performance by compensating for play in both mechanisms, and lowers manufacturing and operational costs while maintaining high precision and reliability under harsh conditions.
Implementation Method 1
a roller screw mechanism with rollers (28) ensuring the conversion of a rotational movement into a translational movement
Implementation Method 2
The preloading device comprises a bearing surface (34) and an elastic ring (35) enclosing the two outer rings (32a and 32b) in contact with one another
Data Source
Figure 1
Figure 2a~2b
Figure 3a~3b
AI summary
The invention relates to a linear actuator comprising a roller screw mechanism (24) guided in rotation relative to a frame (26) by means of two angular contact ball bearings (33a, 33b); the roller screw mechanism (24) comprising rollers (28) interposed between a worm screw (25) and two threaded rings (29a, 29b) linked together in rotation and free in translation, characterized in that each threaded ring (29a, 29b) is integral with an inner ring of a ball bearing (33a, 33b), and in that the linear actuator comprises a single preload device (36) capable of exerting a constraint between two outer rings (32a, 32b) of the angular contact ball bearings (33a, 33b), allowing the roller screw mechanism (24) and the rotational guidance of the roller screw mechanism (24) relative to the frame (26) to be loaded simultaneously.