Hydraulic Valve Spool Position Sensor With Magnetic Shielding
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Solution Overview
Problem
Existing hydraulic valve systems face challenges in accurately monitoring the position of spools within the valve devices, particularly in terms of sensitivity to external magnetic and electrical influences, and the need for a sensor that can measure linear displacement of spools without being affected by these factors.
Innovation Solution
A modular sensor system comprising a magnet housing sealed within the hydraulic valve block and a sensor body with an integrated circuit that senses the angle of magnetic field lines, using a Hall Effect or magneto-resistive sensor, which is insensitive to external magnetic influences and protected from oil ingress, allowing precise measurement of spool position with a spring-loaded plunger and anti-spin device to maintain contact and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a magnetic sensor is used to detect spool position, then measurement precision is improved, but sensitivity to external magnetic and electrical influences worsens
Solution Approach 1:
A non-magnetic intermediary element (the spool itself acting as a moving magnetic shield) is introduced between the magnet and the Hall effect sensor. This intermediary transmits the position information while blocking external magnetic interference, allowing the sensor to detect only the intended magnetic field variations from the moving magnet rather than external disturbances
Solution Approach 2:
The patent replaces traditional mechanical position sensing methods with a magnetic field-based Hall effect sensor system. This substitution enables non-contact measurement, eliminating mechanical wear and improving precision while the specific configuration (magnet on spool, sensor fixed in housing) ensures that only spool-induced field changes are detected, filtering out external magnetic influences
2Measurement precision
If a sensor is installed within the hydraulic valve block to monitor spool movements, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The sensor assembly is merged with the existing hydraulic valve block structure. The Hall effect sensor is housed within the valve body housing, and the magnet is mounted on the existing spool component. This integration eliminates the need for separate external sensor mounting structures and reduces overall system complexity while maintaining high measurement precision
Solution Approach 2:
The spool component serves multiple functions: it acts as both the hydraulic control element and the moving carrier for the magnet that generates the magnetic field signal. This multi-functionality reduces the total number of components needed, as the spool structure is reused for both hydraulic control and position sensing purposes
3Measurement precision
If a Hall effect sensor is used with a magnet mounted on the spool, then measurement precision is improved, but the sensor becomes more sensitive to external magnetic influences
Solution Approach 1:
The spool with the magnet mounted on it serves as a moving intermediary that controls the magnetic field exposure. As the spool moves, it brings the magnet closer to or farther from the Hall effect sensor, creating a position-dependent magnetic field signal. The spool itself acts as a shield, blocking external magnetic fields from reaching the sensor while allowing the controlled magnetic field from the mounted magnet to pass through
Solution Approach 2:
The magnetic field environment is made non-uniform and position-dependent. The Hall effect sensor is positioned to detect only the local magnetic field variations caused by the moving magnet on the spool, while the spool structure and housing provide localized shielding against external magnetic fields. This creates a differentiated magnetic environment where the sensor responds to spool position but is insulated from external interference
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 provides a precise and reliable method for detecting spool position, resistant to external magnetic and electrical interference, suitable for high-pressure applications, with the ability to work across wide temperature ranges and compensate for magnet aging, while being programmable and adaptable to different valve models.
Implementation Method 1
The sensor measures a linear displacement of the spool (21) by sensing an angle of magnetic field lines
Implementation Method 2
using a Hall Effect or magneto-resistive sensor
Data Source
Figure 1
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AI summary
A hydraulic valve device includes a sensor (30) for determining spool displacement of within the valve (20). The sensor includes two main subassemblies, a tube assembly and a body assembly; the tube assembly being mounted onto the valve body by the thread so that the tube together with the valve creates a closed space where oil flows; the plunger (1,2,4,5) with the magnet (4) inside, is kept in contact with the valve spool by the spring (6) so that the magnet (4) moves along with the spool, so does also the magnetic field created by the magnet (4). An integrated circuit on the printed circuit board (11) senses the angle of magnetic field lines and generates an output signal proportional to the movement of the spool.