Actuator Position Sensor with Discrete Magnet Array
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Solution Overview
Problem
Existing position sensors for actuators in industrial control valves face challenges such as mechanical linkage failures under rugged conditions, alignment issues in long-stroke actuators, and the need for a large number of magnets, which increases cost and manufacturing time, especially when transitioning from short-stroke to long-stroke actuators.
Innovation Solution
A position sensor design featuring a housing with a rotatable actuation arm and a magnet array holder that supports a magnetic flux source, allowing relative displacement detection between the sensor and the flux source, with a sector-shaped magnet array holder reducing the number of magnets required by utilizing discrete magnets at strategic positions to provide significant induction changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a non-contacting position sensor is used to improve reliability, then mechanical linkage failures are eliminated, but the number of magnets required increases for long-stroke actuators
Solution Approach 1:
The magnet array is divided into multiple discrete magnet segments arranged along the actuator stroke path. Each magnet segment contributes to the magnetic field at specific positions, allowing the sensor to detect displacement through cumulative field changes rather than requiring a continuous array of magnets throughout the entire stroke length.
Solution Approach 2:
The patent transitions from measuring displacement in a single linear dimension to detecting position through magnetic field variations in three-dimensional space. The sector-shaped sensor detects changes in magnetic flux density along the actuator stroke, converting linear displacement into angular or field intensity measurements that reduce the total number of magnets needed.
2Reliability
If a non-contacting position sensor is used to eliminate mechanical linkages, then reliability improves under rugged conditions, but manufacturing complexity increases due to magnet array configuration
Solution Approach 1:
The position sensor design with discrete magnet segments and sector-shaped sensor configuration can be applied across multiple actuator types and stroke lengths. The same basic sensor assembly works for both short-stroke and long-stroke actuators by adjusting the number and spacing of magnet segments, eliminating the need for completely different sensor designs for different applications.
3Productivity
If discrete magnets are positioned strategically to reduce magnet count, then cost and manufacturing time decrease, but measurement precision may be compromised
Solution Approach 1:
Different regions of the actuator stroke are assigned different magnet densities and configurations. High-precision measurement zones require closer magnet spacing and more magnets, while low-precision zones use sparser magnet arrangements. This local optimization maintains measurement accuracy where needed while reducing overall magnet count and manufacturing complexity.
Solution Approach 2:
The sector-shaped magnetic sensor provides continuous feedback on the magnetic field strength and direction as the actuator moves. This feedback allows the system to compensate for variations in magnet spacing and positioning errors, maintaining measurement precision even with fewer magnets through software-based correction algorithms.
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 enhances sensor reliability and reduces the number of magnets needed, addressing mechanical linkage failures and cost issues while maintaining accurate displacement measurement across various actuator strokes, thereby improving process control in industrial applications.
Implementation Method 1
The magnetic flux source provides a magnetic field that is detected by the sensor. Movement by one or both of the first and second members produces relative displacement to cause a different portion of the magnetic field to be detected by the sensor
Implementation Method 2
a sensor, such as a Hall Effect sensor, to a second member
Data Source
AI summary
Apparatus to determine the position of a movable member of an actuator operating a valve assembly are disclosed. The movable member of the actuator displaces an actuation arm of a position sensor such that relative displacement occurs between a magnetic flux source and a magnetic flux sensor of the position sensor.