Stationary Sensor for Rotary-Linear Actuator Position Detection
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Solution Overview
Problem
Current rotary-linear actuation assemblies require multiple sensors and complex movable supports for precise position detection, leading to alignment issues, increased wear, and maintenance needs, which compromise precision and reliability.
Innovation Solution
A rotary-linear actuation assembly with a stationary position sensor that detects both angular and linear displacements using a mark on the output shaft, eliminating the need for movable supports and simplifying the assembly by utilizing a single sensor to read two-dimensional position information from the shaft's surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple sensors and movable supports are used to detect position, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent combines multiple sensors (optical sensor for angular position and linear sensor for axial position) into a single integrated sensor unit that is stationary relative to the motor housing. This merging eliminates the need for separate movable supports for each sensor, reducing assembly complexity while maintaining the capability to detect both angular and linear positions simultaneously with high precision.
Solution Approach 2:
The integrated sensor unit performs multiple functions: it detects both the angular coordinate and axial coordinate of the output shaft using a single sensor assembly. This multi-functional approach eliminates the need for separate sensing systems and their respective movable supports, thereby reducing overall device complexity while preserving measurement precision.
2Measurement precision
If sensors are mounted on movable supports, then measurement precision is improved, but reliability deteriorates due to wear
Solution Approach 1:
Instead of mounting sensors on movable supports that follow the shaft movement, the patent inverts the approach by making the sensor unit stationary and having the measurement target (mark on the shaft) move relative to it. This eliminates sliding and rolling contacts between sensor mounts and moving parts, removing wear sources while maintaining detection precision through the stationary sensor's observation of the moving mark.
Solution Approach 2:
The patent extracts the sensors from the movable support structure and fixes them stationary relative to the motor housing. This separation removes the sensors from the wear-prone moving components, eliminating the reliability issues associated with bearing and bushing wear while preserving the sensors' ability to accurately track shaft position through their stationary observation point.
3Measurement precision
If movable supports with bearings and bushings are used, then measurement precision is improved, but maintenance requirements increase
Solution Approach 1:
The patent replaces the mechanical movable support system (with bearings, bushings, and sliding contacts) with a stationary sensor mounting system. The measurement function is achieved through the stationary sensor reading the moving mark on the shaft, eliminating mechanical wear components entirely. This substitution removes the need for maintenance of bearings and bushings while maintaining alignment precision through the fixed sensor position.
4Measurement precision
If multiple sensors are used to detect different coordinates, then measurement precision is improved, but manufacturing cost increases
Solution Approach 1:
The patent merges multiple sensing functions (angular position detection and linear position detection) into a single integrated sensor unit. This consolidation reduces the total number of sensor components required, lowering manufacturing costs through reduced part counts, simplified assembly, and reduced calibration requirements, while maintaining the precision benefits of multi-coordinate detection.
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 enhances precision and reliability while reducing maintenance requirements and overall complexity, allowing for precise control of both rotary and linear movements with minimal engagement and maintenance.
Implementation Method 1
an optical displacement probe is used incident upon a target formed from surface features in a rotating component surface
Data Source
Figure 1
Figure 2~2a
Figure 3~3a
AI summary
The present invention concerns a rotary-linear actuation assembly (10, 110) comprising a casing (25, 125) internally housing: an output shaft (14, 113) arranged coaxial with an actuation axis (A) in a translationally and rotationally movable manner; at least two actuators, of which a first actuator (11, 111) is adapted to impose a translational movement along the actuation axis (A) on the output shaft (14, 113) and a second actuator (12, 112) is adapted to impose a rotary movement about the actuation axis (A) on the output shaft (14, 113); and at least one position sensor (30, 130) adapted to detect an instant position of the output shaft (14, 113) inside the casing (25, 125). The assembly is characterised in that the at least one position sensor (30, 130) is mounted in fixed manner in respect of rotation about the actuation axis (A) and in fixed manner in respect of translation along the actuation axis (A), and faces at least a portion (14b, 113a) of the output shaft (14, 113).