Band Sensor Position Measurement for Piston Accumulators
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Solution Overview
Problem
Existing piston accumulator position sensors face issues with mechanical stress, measurement accuracy, and service life due to the use of measuring cable sensors, which are prone to mechanical loading and require complex support systems, and have limited service life when installed in pressure-loaded areas.
Innovation Solution
The use of a measuring band sensor instead of a measuring cable sensor, which reduces mechanical stress and extends service life by eliminating the risk of uncontrolled winding and mechanical loading, and allows for a teach-in method to compensate for varying windup conditions, enabling precise position measurement with minimal complexity and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a measuring cable sensor is used with the rotation axis of the cable drum transversal to the movement direction of the piston, then the position measurement can be performed, but the windup point of the cable drum moves back and forth during windup, causing angular amounts that falsify the measuring results
Solution Approach 1:
The patent changes the orientation of the cable drum rotation axis from being transversal to the piston movement direction to being parallel with it. This asymmetric reorientation eliminates the problematic back-and-forth movement of the windup point, thereby resolving the measurement accuracy issue while maintaining the ability to perform position measurement.
Solution Approach 2:
Instead of accepting the falsified measuring results as a necessary consequence of the transversal orientation, the patent inverts the approach by orienting the rotation axis parallel to the movement direction. This inversion fundamentally changes the geometric relationship and eliminates the source of measurement error.
2Ease of operation
If the measuring cable sensor is mounted with the rotation axis of the cable drum parallel to the movement direction of the piston, then the measuring cable does not have to be deflected, but the service life of the measuring cables is significantly reduced
Solution Approach 1:
The patent replaces the mechanical measuring cable with a magnetic field-based measurement system. Encoder magnets are coupled to the cable drum, and their rotational position is sensed by an angle sensor that detects magnetic fields through the pressure-tight wall. This substitution eliminates the mechanical cable entirely, resolving the service life issue while maintaining installation simplicity.
Solution Approach 2:
The patent introduces encoder magnets as an intermediary between the cable drum rotation and the position measurement. These magnets couple torque-proof to the cable drum and allow contactless sensing of rotational position through the cylinder wall, eliminating the need for mechanical cables that would otherwise be subject to wear and failure.
3Reliability
If a measuring cable sensor is used in the interior of the piston accumulator, then the position sensor is protected, but electrical supply and return requires cable passages that provide sources for leaks
Solution Approach 1:
The patent replaces the electrical cable-based measurement system with a purely mechanical/magnetic system. The angle sensor is positioned outside the pressure-tight cylinder, and it detects the rotational position of encoder magnets through the cylinder wall via magnetic field penetration. This eliminates the need for cable passages penetrating the pressure boundary, thereby eliminating leak sources while maintaining sensor protection.
Solution Approach 2:
The patent extracts the electrical sensing components (angle sensor) from the pressure-loaded interior of the piston accumulator and places them outside the pressure-tight wall. Only the magnetic field needs to penetrate the wall, eliminating the need for physical cable passages and their associated leak risks.
4Adaptability or versatility
If the measuring cable has to be deflected at least once from the unwinding direction into the movement direction of the piston, then the mounting is possible, but the service life of the measuring cables is significantly reduced
Solution Approach 1:
The patent replaces the mechanical measuring cable with a magnetic field-based sensing system. Encoder magnets are coupled to the cable drum and rotate with it, while an external angle sensor detects their position through the cylinder wall. This substitution eliminates the mechanical cable that would otherwise require deflection and suffer from reduced service life, while maintaining full mounting flexibility.
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 measuring band sensor provides improved measurement precision and extended service life, reducing the need for frequent replacements and minimizing the risk of leaks and mechanical damage, while maintaining the pressure tightness of the piston accumulator.
Implementation Method 1
The rotations of the one or plural encoder magnets co-rotating with the cable drum are sensed by an angle sensor that is sensitive to magnetic fields from outside of the cylinder through the pressure tight wall of the cylinder
Data Source
AI summary
A method for using a band sensor for defining a position of a component in an interior of the housing. At least one magnet is coupled with a winding drum of the band sensor so the magnet is drivable in rotation about a magnetic rotation axis wherein a pole axis is disposed transverse to the magnetic rotation axis. The measuring band length varies with percentage of wind-up which is numerically compensated by processing electronics.