Magnetic Stroke Detection for Spool Valves
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Solution Overview
Problem
Existing stroke detection devices for spools in construction machines face challenges in accurately detecting the stroke amount without increasing the device size, as a high set load coil spring can cause the detection rod to remain in contact with the spool even during vibrations or impacts, leading to size increments.
Innovation Solution
A stroke detection device utilizing a magnetic attracting unit with a spherical aligning member and a permanent magnet to attract the detection rod to the spool, combined with a backup spring to maintain contact, allowing for accurate stroke detection without enlarging the device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a coil spring with a large set load is used to maintain contact between the detection rod and spool end surface, then detection accuracy is improved, but the device size increases
Solution Approach 1:
The patent replaces the mechanical coil spring system with a magnetic field-based attracting unit. The attracting unit generates magnetic force to maintain contact between the detection rod and spool end surface, eliminating the need for a large set load coil spring and its associated large diameter coils, thereby reducing device size while maintaining detection accuracy
Solution Approach 2:
The patent changes the physical state and properties of the attracting unit by utilizing magnetic field strength as the controlling parameter instead of mechanical spring load. By adjusting magnetic field parameters, the system achieves the necessary contact force with a more compact structure
2Reliability
If a coil spring with a large set load is used to prevent separation during vibration or impact, then reliability is improved, but the line diameter becomes large
Solution Approach 1:
The patent substitutes the mechanical coil spring system with a magnetic field-based attracting unit. The magnetic force provides consistent attraction force that maintains contact between the detection rod and spool end surface during vibration or impact, achieving reliable contact maintenance without requiring a large line diameter coil spring
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 magnetic attraction provides a strong force for accurate detection without increasing the device's size, maintaining contact with the spool while allowing for precise stroke measurement and maintaining alignment even during spool inclination.
Implementation Method 1
an attracting unit attracted to the end surface of the spool by magnetic force is arranged in the tip end portion of the detection rod
Data Source
AI summary
A stroke detection device for detecting, along a longitudinal direction, a stroke amount of a spool arranged in a valve main body. The stroke detection device includes: a device main body attached to the valve main body; a detection rod extending along the longitudinal direction of the spool, and movably arranged along the longitudinal direction inside the device main body, in a position where a tip end portion faces an end surface of the spool; a stroke detection unit configured to output a detection signal according to the stroke amount of the detection rod with respect to the device main body; and an attracting unit arranged in the tip end portion of the detection rod, the attracting unit being attracted to the end surface of the spool by magnetic force.