Space Actuator With Adjustable Stop For Variable Rotation Rates
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Solution Overview
Problem
Existing rotary aiming devices for space applications face challenges in achieving precise and long-lasting angular movements, as they either have incompatible internal ranges and service lives or require bulky additional systems to achieve the necessary precision and accuracy, especially in the transition from large amplitude deployment to small amplitude fine aiming phases, while also facing lubrication issues in the vacuum of space.
Innovation Solution
An actuator system that utilizes a ball or roller bearing with an adjustable stop and a belt-driven mechanism to convert continuous linear movement into rotary movement, allowing for large amplitude deployment and small amplitude fine aiming with adjustable rotation rates, decoupling the two phases to minimize bearing usage and eliminate the need for lubrication during fine aiming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If a ball or roller bearing is used for rotary movements in space applications, then large amplitude angular movements can be achieved, but the service life is limited due to lubrication difficulties in vacuum
Solution Approach 1:
The patent divides the rotary positioning system into two independent segments: a first ball or roller bearing for deployment phase and a second ball or roller bearing for fine aiming phase. This segmentation allows each bearing to be optimized for its specific function, with the first bearing handling large amplitude movements during deployment and the second bearing handling small amplitude movements during fine aiming, thereby extending overall service life by preventing premature wear of a single bearing
Solution Approach 2:
The patent extracts the fine aiming function from the deployment bearing by introducing a separate second bearing specifically dedicated to fine aiming operations. This extraction allows the first bearing to complete its deployment function without the wear and tear of repeated fine aiming adjustments, thereby extending its service life while the second bearing handles the precision positioning requirements
2Device complexity
If a single bearing is used for both deployment and fine aiming, then device complexity is reduced, but the bearing service life is insufficient for the total number of required actuations
Solution Approach 1:
The patent segments the bearing system into two distinct bearings with different functions: the first bearing is dedicated to deployment phase operations while the second bearing is dedicated to fine aiming phase operations. This segmentation resolves the contradiction by accepting increased device complexity (two bearings instead of one) in exchange for extended service life, as each bearing only needs to withstand the specific operational demands of its designated phase
3Measurement precision
If gear motors with reduction gears are used for precise positioning, then positioning accuracy is improved, but the internal range of movement becomes incompatible with the required service life
Solution Approach 1:
The patent extracts the reduction gear mechanism from the bearing system entirely, using direct-drive ball or roller bearings instead. The positioning accuracy is achieved not through mechanical reduction gears with limited service lives, but through the inherent precision of the bearing geometry and controlled actuation, thereby eliminating the service life limitation imposed by gear teeth wear while maintaining the required positioning accuracy
4Speed
If stepper motors with band reduction gears are used, then deployment speed is improved, but the service life becomes extremely detrimental
Solution Approach 1:
The patent extracts and eliminates the band reduction gear mechanism, using direct-drive ball or roller bearings for both deployment and fine aiming phases. The deployment speed requirement is met through direct actuation of the bearing without mechanical reduction, thereby avoiding the service life deterioration caused by repeated engagement and wear of band gears while maintaining the necessary deployment velocity
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
The actuator system achieves precise and accurate positioning with a long service life, compatible with satellite equipment requirements, by allowing variable rotation rates and minimizing bearing cycles, thus extending the service life and avoiding lubrication needs during fine aiming.
Implementation Method 1
a bearing of the ball or roller type
Implementation Method 2
an adjustable stop is attached to said race and interacts with the sleeve so as to angularly limit the relative rotation of the two races of the bearing
Data Source
AI summary
Actuator for a device for the rotary positioning of a movable element for space equipment comprising a part attached to the fixed portion of said equipment, a bearing, a sleeve designed to actuate the movable portion of said equipment and mounted on an output shaft supported by a first race of said bearing, said actuator comprising a mechanically movable input means and being capable of converting a movement of the input means into a rotary movement of the output shaft about the axis of said bearing, characterized in that said second race of said bearing is connected in rotation to the part of said equipment, in that an adjustable stop so as to angularly limit the relative rotation of the two races of the bearing, and in that the rate of rotation of the output shaft in response to a movement of the input means is different depending on whether or not the sleeve is resting on the adjustable stop.