Reciprocating Compressor TDC Detection via Pressure Waveform Analysis
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Solution Overview
Problem
Conventional diagnostic methods for determining the top-dead-center (TDC) position of reciprocating compressors require the compressor to be powered off, involve costly modifications, and are not suitable for wireless data transmission, especially in industrial environments, due to the need for simultaneous data collection across multiple points.
Innovation Solution
A system using a pressure transducer to measure and convert pressure fluctuations into an asynchronous waveform, with a computing device extracting piston angles, removing invalid data, and determining the TDC position without a phase-reference transducer, enabling wireless data sampling and analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional diagnostic methods using proximity probe and phase-reference transducer are used to determine TDC position, then measurement precision is improved, but device complexity and cost increase due to wiring and modifications
Solution Approach 1:
The patent extracts the TDC detection function from the complex proximity probe and phase-reference transducer system, isolating only the essential pressure sensing function. By using a simple pressure transducer to capture pressure fluctuations and deriving TDC position from the resulting waveform, the system removes unnecessary components (proximity probe, transducer, wiring) while maintaining measurement capability through mathematical analysis of pressure data alone
Solution Approach 2:
The patent replaces the mechanical/electrical sensing system (proximity probe detecting physical position) with a pressure-based sensing system. Instead of mechanically detecting crankshaft position or piston location, the system uses pressure transducer data and waveform analysis to infer TDC position, substituting direct mechanical measurement with indirect pressure-based measurement and computational derivation
2Measurement precision
If compressor is shut down to determine TDC position using dial indicator or level, then measurement precision is improved, but productivity decreases due to shutdown requirement
Solution Approach 1:
The patent performs preliminary data collection and analysis by capturing pressure waveform data during normal compressor operation. By continuously monitoring pressure fluctuations and identifying characteristic waveform patterns that indicate TDC position, the system prepares and determines TDC information in advance without requiring shutdown, allowing the compressor to remain operational while diagnostic data is gathered and processed
Solution Approach 2:
The patent maintains continuous diagnostic measurement capability during compressor operation. The pressure transducer continuously captures pressure data, and the system continuously analyzes waveforms to track TDC position in real-time throughout the compressor's operating cycle, eliminating interruptions and maintaining both productivity and measurement capability simultaneously
3Measurement precision
If simultaneous data collection from pressure transducer and phase-reference transducer is required, then measurement precision is improved, but ease of operation worsens due to difficulty in ensuring simultaneous transmission
Solution Approach 1:
The patent removes the phase-reference transducer component entirely from the data collection system. By extracting only the pressure transducer data and using waveform analysis to identify TDC position, the system eliminates the need for synchronized data collection from multiple sources. The solution relies solely on pressure waveform characteristics, removing the complexity of coordinating simultaneous data transmission from multiple transducers
Solution Approach 2:
The pressure transducer serves multiple functions: it monitors compressor pressure for operational control and simultaneously provides the data needed for TDC position determination. By making the pressure sensing system universal, the patent eliminates the need for separate phase-reference transducer and synchronized data collection infrastructure, simplifying the system while maintaining diagnostic precision
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 allows for accurate determination of the TDC position without shutting down the compressor, reduces costs by eliminating the need for wiring and modifications, and facilitates wireless data transmission, improving diagnostic efficiency in industrial settings.
Implementation Method 1
a pressure transducer configured to measure pressure fluctuations inside a compressor cylinder and convert the pressure fluctuations into an asynchronous waveform
Data Source
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AI summary
An apparatus for determining a top-dead-center (TDC) of a reciprocating compressor (14) includes: a pressure transducer (17) configured to measure pressure fluctuations inside a compressor cylinder (15) and convert the pressure fluctuations into an asynchronous waveform; and at least one computing device (20) operably connected with the pressure transducer (17). The at least one computing device (20) is configured to: extract a data set representing piston angles over a single revolution of a piston (16) within the compressor cylinder (15) from the asynchronous waveform; evaluate a property corresponding to the measured pressure at each piston angle of the revolution data set; determine whether each piston angle of the revolution data set is an invalid piston angle that does not correspond to a TDC position of the piston based at least in part on a comparison of the evaluated property from the respective piston angle to a respective threshold; remove data representing invalid piston angles from the revolution data set to form a refined data set; determine an average piston angle for the single revolution from the refined data set; identify the average piston angle representing a data value of the refined data set as the TDC position of the piston; and adjust the refined data set to identify a TDC position of the piston to be a first data value in the refined data set.