Variable Compressor Displacement Detection via Waveform Pattern Analysis
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Solution Overview
Problem
Existing displacement detection methods for variable displacement compressors are sensitive to shape restrictions, cost-intensive, and prone to errors due to external disturbances such as abrasion, cracks, and temperature fluctuations, requiring high machining precision and being susceptible to detection inaccuracies.
Innovation Solution
A displacement detection device that uses a position detection sensor placed laterally to the piston, where the side surface moving in the traverse direction is the detection surface, allowing for waveform pattern analysis of piston stroke to estimate displacement without requiring high accuracy in piston shape, and is robust against disturbances by comparing waveform patterns to estimate current operational displacement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a tapered shape or stepped shape is formed on the piston neck part as a surface to be detected, then the position detection sensor can detect piston stroke changes, but the manufacturing cost increases and the piston weight increases due to increased thickness
Solution Approach 1:
The patent uses a magnetic field signature or electromagnetic pattern as a 'copy' of the piston position rather than requiring a physical tapered or stepped surface. The position detection sensor detects changes in magnetic field characteristics caused by the piston's movement, eliminating the need for complex mechanical shaping of the piston itself.
Solution Approach 2:
The patent replaces the mechanical tapered/stepped surface with a magnetic field-based detection system. Instead of shaping the piston mechanically to create detectable features, the system uses magnetic field interactions to sense piston position, substituting mechanical complexity with electromagnetic field manipulation.
2Measurement precision
If a tapered shape is formed on the piston neck part, then piston stroke can be detected, but the piston weight increases due to increased thickness
Solution Approach 1:
The patent uses a magnetic field signature or electromagnetic pattern as a 'copy' of the piston position rather than requiring a physical tapered or stepped surface. The position detection sensor detects changes in magnetic field characteristics caused by the piston's movement, eliminating the need for complex mechanical shaping of the piston itself.
Solution Approach 2:
The patent replaces the mechanical tapered/stepped surface with a magnetic field-based detection system. Instead of shaping the piston mechanically to create detectable features, the system uses magnetic field interactions to sense piston position, substituting mechanical complexity with electromagnetic field manipulation.
3Measurement precision
If displacement is calculated from the distance between the surface to be detected and the position detection sensor, then piston stroke can be measured, but the system becomes sensitive to disturbances such as foreign substances, abrasion, cracks, and temperature fluctuations
Solution Approach 1:
The patent replaces direct mechanical distance measurement with magnetic field-based detection. The position detection sensor measures changes in magnetic field characteristics rather than direct physical distance, making the system immune to foreign substances, abrasion, and cracks that would interfere with mechanical contact-based measurement.
Solution Approach 2:
The patent introduces a magnetic field as an intermediary between the piston and the detection sensor. Instead of direct mechanical interaction that is susceptible to disturbances, the magnetic field serves as a non-contact mediator that transmits position information without being affected by foreign substances, surface degradation, or temperature variations.
4Measurement precision
If a tapered shape is formed on the piston neck part, then position detection is enabled, but the piston design becomes more complex and requires high dimensional accuracy
Solution Approach 1:
The patent uses a magnetic field signature or electromagnetic pattern as a 'copy' of the piston position rather than requiring a physical tapered or stepped surface. The position detection sensor detects changes in magnetic field characteristics caused by the piston's movement, eliminating the need for complex mechanical shaping of the piston itself.
Solution Approach 2:
The patent replaces the mechanical tapered/stepped surface with a magnetic field-based detection system. Instead of shaping the piston mechanically to create detectable features, the system uses magnetic field interactions to sense piston position, substituting mechanical complexity with electromagnetic field manipulation.
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 approach reduces costs by allowing flexible piston shapes, enhances accuracy by minimizing the impact of external disturbances, and enables precise estimation of compressor displacement with reduced computational load, facilitating real-time measurement.
Implementation Method 1
A contactless type position detection sensor is placed laterally to the piston as facing the surface to be detected. The position detection sensor detects the distance between the position detection sensor and the surface (detection point) to be detected
Data Source
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AI summary
Provided is a displacement detection device for a variable displacement compressor which has a configuration such that the displacement detection device can estimate the displacement with little effect from external disturbances, and can be used with pistons that do not require a high degree of machining precision, thus allowing for a greater degree of freedom in the shape of the surface to be detected. Also provided is a variable displacement compressor provided with the displacement detection device. The displacement detection device for a variable displacement compressor is equipped with: a position detection sensor, which is disposed laterally to the piston and outputs a surface displacement signal for the surface to be detected when the piston moves in a reciprocating manner; and an estimation means that measures and stores the waveform pattern (A) of the displacement signal for a stroke of the piston during operation at maximum displacement, detects the waveform pattern (B) of the displacement signal for one stroke of the piston in the current operating state, and estimates the displacement of one stroke of the piston in the current operating state from a comparison of waveform pattern (A) and waveform pattern (B).