Stroke Amount Detection Using Opposing Magnetic Field Members
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Solution Overview
Problem
Conventional stroke amount detecting devices suffer from detection errors due to machining or assembling errors and positional displacement of magnetic sensor elements, leading to insufficient robustness and linearity issues in magnetic flux density detection.
Innovation Solution
A stroke amount detecting device is designed with magnetic field generation members magnetized in opposite directions perpendicular to the stroking axis, ensuring uniform magnetic flux vectors along the stroke direction, and a magnetic sensor unit positioned to detect these fluxes, which improves robustness and linearity by maintaining consistent magnetic flux density detection even with perpendicular displacement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If magnets are arranged with tapered surfaces unevenly angled relative to the stroke direction, then detection errors occur due to machining or assembling errors, but the device complexity increases to compensate for these errors
Solution Approach 1:
The patent applies asymmetry by configuring magnets with opposite polarities on either side of the stroke range, creating an asymmetric magnetic field distribution that compensates for machining and assembling errors. This asymmetric arrangement ensures that detection errors are minimized without requiring complex corrective mechanisms.
Solution Approach 2:
The patent changes the magnetic field parameters by arranging magnets with opposite polarities and specific orientations relative to the stroke direction. This parameter change creates a magnetic field configuration that is inherently more tolerant to manufacturing variations, improving detection accuracy without increasing device complexity.
2Measurement precision
If the magnetic sensor element position is displaced from the stroke direction, then detecting magnetic flux density varies resulting in detection errors, but adding compensation mechanisms increases device complexity
Solution Approach 1:
The patent creates an equipotential magnetic field environment by arranging magnets with opposite polarities symmetrically around the stroke range. This configuration ensures that the magnetic flux density remains relatively constant across the sensor's movement path, making the detection accurate even when the sensor is displaced from the ideal stroke direction.
Solution Approach 2:
The magnetic field configuration serves multiple functions: it provides the primary detection field, compensates for sensor displacement, and maintains detection accuracy across the stroke range. This multi-functional design eliminates the need for separate compensation mechanisms, reducing device complexity.
3Measurement precision
If tapered magnets are arranged on both sides of the stroke range with opposite magnetization directions, then linearity of output signals is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent segments the magnetic field generation into multiple independent magnets arranged on both sides of the stroke range. Each magnet can be manufactured and positioned independently with standard tolerances, and their combined effect produces the desired linear output signal, reducing the overall manufacturing precision requirements compared to a single complex magnet.
Solution Approach 2:
The patent applies different magnetization directions to magnets on opposite sides of the stroke range, creating local quality variations that collectively produce improved linearity. Each magnet's specific orientation is optimized for its local position, and the combination of these localized optimizations achieves global linearity improvement without requiring ultra-precise manufacturing.
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 solution enhances the robustness and linearity of stroke amount detection, reducing detection errors and improving the device's resistance to positional displacement and manufacturing complexities, while simplifying the magnetic circuit design and reducing manufacturing costs.
Implementation Method 1
a magnetic flux density detected by a magnetic sensor element continuously changes in a manner of strong, weak, strong
Implementation Method 2
The magnetic sensor unit has a magnetosensitive surface facing a direction parallel to the traveling axis for detecting an amount of stroke of the object
Data Source
AI summary
A stroke amount detecting device includes a first magnetic field generation member, a second magnetic field generation member, and a magnetic sensor unit. The first magnetic field generation member and the second magnetic field generation member are opposed to each other with respect to a direction perpendicular to a straight stroking axis of a stroking object, and magnetized in opposite directions. The magnetic sensor unit is movable in an area between the first magnetic field generation member and the second magnetic field generation member, along a straight traveling axis that is parallel to the straight stroking axis relative to the first magnetic field generation member and the second magnetic field generation member in accordance with a stroke motion of the stroking object. The magnetic sensor unit has a magnetosensitive surface facing a direction parallel to the traveling axis, thereby to detect an amount of stroke of the object.