Piston-Cylinder Sensor Sealing for High-Pressure Position Sensing
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Solution Overview
Problem
Existing piston-cylinder units with integrated piston motion sensors face challenges in mounting and detaching effort, component complexity, and stress on the sensor due to high fluid pressures, which affect manufacturing tolerances and compatibility with different cylinder dimensions.
Innovation Solution
The piston-cylinder unit design fluidically separates the transverse bore from the pressure chamber, using a sealing element and dielectric lens or collimator to ensure sensor signal transmission while preventing fluid leakage, and employs a positioning and alignment element to maintain accurate sensor placement and alignment, allowing for easy detachment and adaptation to different cylinder dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the piston motion sensor is integrated in the transverse bore of the cylinder head and pressurised with hydraulic fluid, then the sensor can detect piston position accurately through the pressure chamber, but the sensor housing must withstand high fluid pressures which complicates manufacturing and increases stress on the sensor
Solution Approach 1:
The transverse bore is divided into two fluidically separate regions: a first region in communication with the pressure chamber for sensor signal transmission, and a second region for receiving the sensor housing. This segmentation allows the sensor to be exposed to pressure for accurate measurement while the housing can be protected from extreme pressures through the sealing element at the interface between regions.
Solution Approach 2:
A sealing element is introduced as an intermediary component at the interface between the first and second regions of the transverse bore. This sealing element fluidically separates the high-pressure zone (first region) from the lower-pressure sensor housing zone (second region), allowing pressure transmission for measurement while protecting the sensor housing from withstanding full hydraulic pressure.
2Loss of information
If the piston motion sensor is mounted in the transverse bore with fluidic connection to the pressure chamber, then sensor signal can be transmitted through the pressure chamber to the piston, but mounting and detaching effort increases due to sealing requirements
Solution Approach 1:
The transverse bore is segmented into functional zones with a sealing element that creates a defined interface. This segmentation allows the sensor housing to be mounted and detached from the second region while maintaining the seal with the first region, simplifying installation and removal procedures compared to fully integrated sealed designs.
Solution Approach 2:
The sealing element acts as an intermediary that enables both functions: it maintains fluidic separation for signal transmission integrity while providing a manageable interface for mounting and detaching the sensor housing. The seal allows controlled interaction between the pressurised first region and the sensor housing in the second region.
3Measurement precision
If the piston motion sensor is integrated in the cylinder head, then the sensor placement is fixed for accurate measurement, but adapting to different cylinder dimensions requires precise manufacturing tolerances
Solution Approach 1:
The positioning element provides an adjustable or adaptable mechanism within the transverse bore that allows the piston motion sensor to be positioned accurately regardless of cylinder dimension variations. This dynamic positioning capability compensates for manufacturing tolerances in the cylinder head while maintaining precise sensor alignment for accurate measurement.
Solution Approach 2:
The positioning element enables the sensor mounting system to self-adjust to different cylinder dimensions without requiring extremely tight manufacturing tolerances on the cylinder head itself. The positioning mechanism provides the necessary alignment precision independently, allowing the cylinder head to be manufactured with more practical tolerances.
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 design enhances the ease of mounting and detachment of the piston motion sensor, reduces stress on the sensor, and ensures accurate measurement by maintaining sensor alignment and compatibility across various cylinder dimensions, while withstanding high hydraulic pressures.
Implementation Method 1
withstand high hydraulic pressures
Implementation Method 2
sensor signal travels from the piston motion sensor through the pressure chamber to the piston or a piston rod. The sensor signal is reflected by the piston or the piston rod
Implementation Method 3
in particular the piston movement, for example a stroke, is detected by the change in the running time of the sensor signal depending on the position of the piston or piston rod
Data Source
AI summary
The invention relates to a piston-cylinder unit. A piston motion sensor is arranged in a transverse bore of a cylinder head of the piston-cylinder unit. According to the invention, the transverse bore is separated from a pressure chamber which pressurises a piston of the piston-cylinder unit. This separation can be achieved by a collimator arranged in the beam path of a sensor signal being sealed off from a sensor signal channel by means of a sealing element. The seal can be used to enable the housing of the piston movement sensor to be detached from the transverse bore without the fluid escaping from the pressure chamber into the environment.The piston-cylinder unit can be used, for example, for a working machine, construction machine, agricultural machine, maritime machine, wheel loader, digger, dump truck, crane, forklift or lifting platform.