Linear Actuator Magnetic Position Calibration Without Wear
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Solution Overview
Problem
Existing incremental position detection systems in linear actuators face inaccuracies and unreliability due to mechanical components that wear out and are prone to losing pulses, especially when not frequently moved against end stops, requiring precise synchronization and calibration.
Innovation Solution
The use of magnetic sensors and magnets within the actuator's housing, where the magnetic sensors detect the proximity of a magnet on the spindle nut, allowing for electronic calibration and accurate position detection without mechanical parts, using digital or analogue sensors to provide reliable position determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical switches or incremental sensors are used for position detection, then the system can detect position changes, but the mechanical components wear out and become unreliable over time
Solution Approach 1:
The patent replaces mechanical switches and incremental sensors with a magnetic field-based position detection system. A magnet is attached to the movable element (spindle nut or activation element), and a magnetic sensor (such as a Hall sensor or reed switch) detects the magnetic field changes as the magnet moves past it. This eliminates mechanical contact and wear, providing reliable position detection throughout the entire service life of the actuator without the degradation associated with mechanical components.
2Ease of manufacture
If incremental position detection systems are used, then cost is reduced compared to potentiometers, but the system requires frequent calibration and synchronization
Solution Approach 1:
The magnetic position detection system provides automatic self-calibration through the use of a magnet attached to the movable element. As the magnet passes by the magnetic sensor during normal operation, it generates a reference signal that automatically synchronizes the position counter with the actual physical position. This eliminates the need for manual calibration procedures and ensures continuous accuracy without requiring user intervention or system downtime for maintenance.
3Measurement precision
If mechanical switches are used for position synchronization, then initiation points can be detected, but the mechanical activation key is activated in different positions depending on direction of movement
Solution Approach 1:
The patent replaces mechanical switches with a magnetic sensor that detects the position of a magnet attached to the movable element. The magnetic sensor remains stationary while the magnet moves past it during actuator operation. This configuration ensures that the reference signal is always generated at the same physical location regardless of the direction of movement, eliminating the directional dependency problem inherent in mechanical switch systems and providing consistent, accurate position synchronization in both directions.
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 provides a more accurate and reliable position detection system that is not mechanically worn and avoids the limitations of mechanical switches, ensuring precise synchronization and maintaining accuracy over time, even when the system is not frequently used.
Implementation Method 1
The position detection system comprises at least one magnetic sensor arranged in a position on a length parallel to the axial direction of extent of the spindle, and a magnet arranged in connection with the spindle nut or the activation element
Data Source
Figure 1
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Figure 3~4
AI summary
Linear electric actuator (1) comprising a housing (10) with a reversible DC-motor (2), which through a transmission (3) can move an activation element (6) between two end positions, where an incremental position detection system is adapted to indicate the position of the spindle nut (5) during its travel on the spindle (4) and where the accuracy of the position detection system continuously is calibrated in that a magnet (15) is arranged in connection with the spindle nut (5), and at least one magnetic sensor (13,14) is arranged within the housing (10) of the actuator in a position where a proximity with the magnet (15) arranged in connection with the spindle nut (5) on its travel on the spindle (4) is achieved to establish a reference point for the position detection system.