Compressor Fault Detection Using Speed-Normalized Pressure Gradients
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Solution Overview
Problem
Existing methods for monitoring the function of compressors in compressed air supply systems are not suitable for variable drive speeds and fail to differentiate between fault causes, making it difficult to detect faults early and plan maintenance effectively.
Innovation Solution
A method that continuously detects supply pressure and calculates pressure gradients, weighting them with current drive speed or delivery rate, and compares these weighted gradients with predetermined limits to output warnings, while accounting for variable drive speeds and eliminating the influence of drive speed on pressure readings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pressure gradient monitoring is performed during compressor operation, then fault detection capability is improved, but the monitoring results are inaccurate when drive speed varies
Solution Approach 1:
The patent transforms the monitoring parameter from raw pressure gradient to speed-normalized pressure gradient. By dividing the pressure gradient by drive speed, the monitoring metric becomes independent of speed variations, allowing accurate fault detection across different operating conditions. This parameter transformation resolves the contradiction by making measurements accurate regardless of drive speed changes.
2Measurement precision
If speed-dependent monitoring thresholds are implemented, then fault detection accuracy is improved, but device complexity increases
Solution Approach 1:
Instead of implementing complex speed-dependent thresholds, the patent simplifies the approach by normalizing the pressure gradient with drive speed. This transformation creates a universal monitoring metric that maintains constant reference values across all speeds, achieving accurate fault detection without requiring complex adaptive threshold mechanisms.
3Reliability
If continuous pressure gradient monitoring is performed, then early fault recognition is improved, but false warnings increase due to drive speed variations
Solution Approach 1:
The patent eliminates false warnings by transforming the monitoring parameter to speed-normalized pressure gradient. This parameter change removes the confounding effect of drive speed variations, allowing continuous monitoring to accurately distinguish between normal speed-related pressure changes and actual fault conditions, thereby reducing false alarm rates.
Data Source
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AI summary
A method for monitoring the functioning of a compressor (2) which can be shifted into a delivery mode, which compressor (2) when in the delivery mode delivers compressed air into at least one main supply line (26, 28) via a drier line (18) of a compressed-air-preparation unit (6), from which main supply line (26, 28) a plurality of supply lines (44, 48, 52, 56, 60) branch off from compressed-air consumer circuits (V21-V25), wherein a pressure sensor (82, 88, 94) is respectively connected to at least some of the supply lines, having the following method steps: a) continuous sensing of the supply pressure (pv) in a main supply line or in a supply line; b) continuous calculation of the pressure gradients (grd_ p v) of the supply pressure (p v) from in each case at least two successively acquired pressure values (Pv i, Pv_i+1) and the time difference t between their acquisition; c) weighting of the pressure gradients (grd_ p v) by division by the current drive rotational speed (n K) or by the current rotational-speed-dependent setpoint delivery quantity (QSOLL) of the compressor; d) comparison of the weighted pressure gradients (grd_ P v_w ) with a prescribed gradient limiting value (grd_ P g _w ); and e) outputting of a warning message if the weighted pressure gradient (grd_ p v_w ) has not exceeded the gradient limiting value (grd _p G_W) within a prescribed monitoring time period (T M). Alternatively, the above steps c), d) and e) can be replaced by the following method steps: c) comparison of the pressure gradients (grd _P V) with a respective current gradient limiting value(grd _P G) which has been prescribed as a function of the rotational speed and which does not take into account the removal of compressed air by the consumers, and d) outputting of a warning message or warning signal if the pressure gradient(grd _P V) has not exceeded the respective gradient limiting value (grd _P G) within a prescribed monitoring time period (T M).