Displacement Machine Monitoring via Position-Dependent Pressure Profiling
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Solution Overview
Problem
Current methods for monitoring displacement machines, such as positive-displacement pumps and compressors, are costly and inadequate for early detection of faults or damage, as they rely on expensive sensor technology and complex frequency analysis that only allows limited determination of fault causes.
Innovation Solution
A method and device that detect system pressure as a function of displacer position using conventional sensors, correlating displacer positions with system pressure values to create a displacer-dependent pressure profile, which is compared to an expected curve for early malfunction detection, employing filtering to isolate synchronous signal components and prevent blurring over time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If expensive sensor technology is used to monitor pressure medium impurities, then measurement precision is improved, but device cost increases
Solution Approach 1:
The patent replaces expensive specialized sensors with conventional, inexpensive pressure sensors that are already available in the system. Instead of using costly dedicated impurity sensors, the invention uses readily available pressure measurement devices to achieve fault detection through pressure profile analysis during the displacement cycle.
Solution Approach 2:
The patent substitutes direct mechanical/physical impurity sensing with a indirect measurement approach using pressure field analysis. By monitoring pressure variations throughout the displacement cycle and analyzing the pressure profile, the system can detect faults without requiring specialized impurity sensors.
2Reliability
If complex frequency analysis with Fourier transformation is performed on system pressure, then fault detection capability is improved, but device complexity and hardware costs increase
Solution Approach 1:
The patent extracts only the essential information needed for fault detection by comparing pressure profiles at specific displacement positions, rather than performing a complete Fourier transformation. This selective approach focuses on the most diagnostic pressure variations without requiring complex signal processing hardware.
Solution Approach 2:
Instead of transforming pressure data from time domain to frequency domain through Fourier transformation, the patent inverts the approach by directly analyzing pressure profiles in the displacement domain. By comparing actual pressure profiles with reference profiles at corresponding displacement positions, the system achieves fault detection without complex mathematical transformations.
3Device complexity
If system pressure values are averaged over the periodic movement of the displacer, then device complexity is reduced, but measurement precision and early fault detection capability deteriorate
Solution Approach 1:
The patent divides the displacement cycle into multiple discrete positions and records pressure values at each position separately rather than averaging over the entire cycle. This segmentation allows the system to create a detailed pressure profile showing pressure variations at specific points in the displacement cycle, enabling detection of subtle faults that would be masked by averaging.
Solution Approach 2:
The patent performs preliminary recording of pressure values at multiple discrete displacement positions before any analysis takes place. By capturing the complete pressure profile data first, the system preserves all diagnostic information for later comparison with reference profiles, enabling early fault detection without losing subtle variations.
4Loss of information
If multiple sensors for recording operating data are arranged in the displacement machine, then measurement completeness is improved, but device complexity and cost increase
Solution Approach 1:
The patent makes the pressure sensor multi-functional by using it for multiple measurement positions throughout the displacement cycle. Instead of installing separate sensors at different locations, the single pressure sensor records pressure at multiple discrete positions during the displacer's periodic movement, achieving comprehensive monitoring with minimal hardware.
Solution Approach 2:
The patent uses the existing periodic movement of the displacer itself to bring the pressure sensor to different effective measurement positions. The displacer's own motion serves the dual purpose of performing work while simultaneously enabling the pressure sensor to sample pressure at multiple points in the cycle, eliminating the need for additional sensors or complex positioning mechanisms.
Data Source
Figure 1~2
Figure 3A~3B
AI summary
The method involves detecting system pressure in packets as a set of temporally equidistantly sensed system pressure values based on a displacement body position in a working chamber. The resultant displacement body position-dependent system pressure is compared with an expected displacement body position-dependent system pressure to determine failure malfunctions. The detected pressure is filtered. Measured values of the detected pressure are detected in a table, where an actual displacement body position is utilized as an index. Storage spaces of the table are updated with a filter function. An independent claim is also included for a device for monitoring a displacement machine.