Radial RF Piston Position Sensing for Retrofit Hydraulic Cylinders
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Solution Overview
Problem
Existing piston-cylinder units, particularly in working machines, face challenges in accurately detecting the axial position of the piston using conventional methods, which are often complex and expensive, such as magnetostrictive sensors, and require significant modifications or disassembly for retrofitting with advanced position detection systems.
Innovation Solution
A compact, high-frequency piston position detection unit is designed as a self-sufficient cartridge that can be easily retrofitted into existing piston-cylinder units, using a housing made of materials like PEEK for high-pressure resistance and signal permeability, with an antenna system for radio frequency signal transmission and reception, allowing for precise position detection without structural changes or disassembly of the unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If magnetostrictive sensors are used for piston position detection, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces complex magnetostrictive sensors with a simplified high-frequency radar system using microwave technology. The radar sensor uses an antenna to emit and receive electromagnetic waves, eliminating the need for magnetostrictive materials and complex signal processing electronics, thereby reducing device complexity while maintaining measurement precision for piston position detection
Solution Approach 2:
The patent extracts only the essential function of position detection from complex sensor systems. By using a radar antenna that directly measures the distance to the piston through electromagnetic wave reflection, it removes unnecessary complex components such as magnetostrictive rods, coils, and evaluation electronics, achieving simpler construction with adequate measurement accuracy
2Measurement precision
If advanced position detection systems are retrofitted into existing piston-cylinder units, then measurement precision is improved, but ease of manufacture deteriorates due to significant modifications required
Solution Approach 1:
The patent segments the position detection system into a separate, modular radar sensor unit that can be independently installed. The radar sensor is housed in its own housing with separate mounting requirements, allowing it to be retrofitted into existing piston-cylinder units without modifying the original cylinder or piston structure, thus improving ease of manufacture while achieving precise position detection
Solution Approach 2:
The patent introduces a separate housing as an intermediary component between the radar antenna and the hydraulic environment. This housing serves as a mounting carrier that interfaces with the existing piston-cylinder unit through a mounting bore, allowing the advanced detection system to be installed without direct modification to the original structure, simplifying the retrofitting process
3Ease of operation
If a radial mounting bore is used for the piston position sensing unit, then ease of operation is improved for retrofitting, but the cylinder structure may be weakened
Solution Approach 1:
The patent uses a sealed housing as a protective shell for the radar antenna. This housing can be mounted in a radial bore and provides structural integrity while protecting the electronic components. The housing acts as a self-contained unit that minimizes the impact on cylinder strength while enabling easy retrofitting through the radial mounting approach
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 enables accurate and efficient detection of piston position within the cylinder, allowing for safe end-positioning, automation, and overload monitoring, without requiring significant material changes or weakening of the cylinder structure, and can be installed or replaced without emptying or filling the hydraulic system.
Implementation Method 1
an antenna for transmitting and receiving radio frequency signals through the housing
Data Source
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AI summary
A piston-cylinder unit (1) of a working machine, e.g., a wheel loader, excavator, dump truck, crane, forklift, or lifting platform, serves to steer, support, extend, tilt, lift, or otherwise move the working machine or a tool or other part of the working machine. The piston-cylinder unit (1) comprises a cylinder (2), a piston (7) axially movably mounted in the cylinder (2), and a piston position sensing unit (28). The piston position sensing unit (28) uses high-frequency technology to detect the axial position of the piston (7) in the cylinder (2). The piston position sensing unit (28) is arranged in a mounting bore (27) extending radially in the cylinder (2).