Sensor Unit With Pressure-Tight Wall for Cylinder Position Detection
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Solution Overview
Problem
Existing sensor units for detecting piston position in operating cylinder units face challenges in harsh environments due to sensitivity, cost, and risk of damage, particularly when exposed to high pressure and aggressive media, and require complex modifications to the cylinder structure.
Innovation Solution
A sensor unit with a tension element travel distance sensor, where the tension element is preloaded on a winding drum and coupled magnetically with an encoder magnet, is separated from the winding drum by a pressure-tight wall, allowing the sensor to be housed in a low-pressure cavity while mechanical components are in a high-pressure cavity, reducing the risk of damage and complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the sensor is arranged in the positive pressure space inside the cylinder, then the measurement function is achieved, but the sensor is exposed to high pressure and aggressive media causing damage
Solution Approach 1:
The invention divides the cylinder into two separate pressure spaces using a pressure-tight wall: a positive pressure space containing the mechanical components (winding drum, tension element, encoder magnet) and a negative pressure space containing the sensor. This segmentation allows each component to operate in its appropriate pressure environment, protecting the sensor from high pressure while maintaining the measurement function.
Solution Approach 2:
The pressure-tight wall acts as an intermediary barrier between the positive and negative pressure spaces. It physically separates the sensor from the harsh high-pressure environment while allowing magnetic field transmission through the wall, enabling the sensor to detect encoder magnet position without direct exposure to harmful conditions.
2Reliability
If the sensor unit is arranged outside the cylinder, then the sensor is protected from high pressure, but the sensor is exposed to rough environmental conditions causing damage
Solution Approach 1:
The invention segments the sensor unit into two distinct environments: the sensor is housed in the negative pressure space inside the cylinder (protected from external environmental damage), while the mechanical components remain in the positive pressure space. This internal segmentation provides dual protection against both high pressure and external environmental factors.
3Measurement precision
If the cylinder is modified with windows or thinner walls for magnetic field transmission, then the sensor can detect encoder magnet position, but the fabrication cost increases and pressure bearing capacity decreases
Solution Approach 1:
The pressure-tight wall is designed with locally optimized properties: it is thick and strong in most areas to maintain pressure bearing capacity, but includes localized magnetic field transmission regions (such as magnetic field windows or sections made of magnetic field permeable material) that allow the encoder magnet's magnetic field to pass through to the sensor without compromising overall structural integrity.
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 configuration reduces the risk of sensor damage, simplifies installation, and eliminates the need for complex cylinder modifications, maintaining measurement precision while reducing production costs and environmental exposure risks.
Implementation Method 1
a magnetic field sensitive sensor arranged on an outside of the pressure tight wall in a magnetic effective range of the encoder magnet, wherein the pressure tight wall is configured so that a magnetic field of the encoder magnet is detected and measured by the magnetic field sensitive sensor
Data Source
AI summary
In order to arrange a sensor unit completely in an interior e.g. of a cylinder of a piston cylinder unit and in order to be able to use a tension element sensor as a sensor the sensor unit is configured so that it includes a pressure tight wall through which a magnetic field sensitive sensor is configured to detect a magnetic field of an encoder magnet that moves on another side of the pressure tight wall and represents a rotational position and rotations of the winding drum whereas a housing of the sensor unit is sealed relative to an interior of the cylinder so that the sensor cavity in which the sensor is arranged represents a low pressure cavity which is advantageously only subjected to ambient pressure. This avoids hollow boring of the piston rod and no magnetic field permeable window has to be fabricated in a wall or in a base of the cylinder.