Acoustic Operating Point Detection for Centrifugal Pumps
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Solution Overview
Problem
Existing methods for determining the operating point of a centrifugal pump, particularly in cases with non-unique or ambiguous flow-head and flow-performance characteristic curves, require significant measurement effort and expertise, often involving electrical measurements that are costly and labor-intensive.
Innovation Solution
The method determines the operating point of a centrifugal pump using mechanical variables such as pressure, differential pressure, force, vibration, or sound analysis, specifically analyzing the rotational sound frequency to calculate the speed and torque of the asynchronous motor, thereby eliminating the need for electrical measurements and simplifying the process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If electrical measurements (current and voltage) are used to determine operating point, then power consumption can be calculated, but installation requires qualified electrician and takes up space in control cabinet
Solution Approach 1:
The patent replaces electrical measurement systems (current transformers, power measuring devices requiring electrician installation) with acoustic measurement systems. A simple acoustic sensor detects motor sound to determine operating point and power consumption, eliminating the need for complex electrical instrument installation while maintaining measurement capability.
2Measurement precision
If Q-H characteristic curve is used to determine delivery rate from pressure, then delivery rate can be calculated, but the curve is often flat or ambiguous making determination difficult or impossible
Solution Approach 1:
The patent introduces acoustic signal as an intermediary measurement parameter. Instead of directly using the ambiguous Q-H characteristic curve relationship, the system measures motor sound which correlates with operating point, then uses this acoustic information to reliably determine delivery rate without being constrained by flat or ambiguous pressure-flow characteristics.
3Measurement precision
If direct flow rate measurement is used, then accurate delivery rate is obtained, but magnetic-inductive flow meters are expensive and require significant measurement effort
Solution Approach 1:
The patent replaces expensive magnetic-inductive flow meters with inexpensive acoustic sensors. The acoustic measurement system provides sufficient measurement precision for delivery rate determination at a fraction of the cost and complexity of direct flow measurement instruments.
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 a cost-effective and straightforward determination of the operating point, reducing the complexity and effort required compared to conventional methods, while providing accurate results without the need for electrical measurement variables.
Implementation Method 1
a mechanical measured variable pressure, differential pressure, force, vibration, structure-borne noise or airborne sound is detected by a sensor
Implementation Method 2
a frequency which is linearly proportional to a rotational sound of the work machine is determined from the signal curve of the measured variable by means of a signal analysis, in particular frequency analysis
Implementation Method 3
specifically analyzing the rotational sound frequency to calculate the speed and torque of the asynchronous motor
Data Source
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AI summary
The present invention relates to a method and a device for determining an operating point of a work machine and/or of an asynchronous motor driving the same, wherein an operating point is characterized by a power consumed by the work machine and/or by the output rate thereof, one or more operating point-dependent measurement variables of the work machine are detected by one or more sensors, and the measured values are evaluated and/or stored during operation of the work machine. The operating point is determined without the use of electric measurement variables of the driving asynchronous motor in that a frequency that is linearly proportional to the fundamental tone of the work machine is determined by means of a signal analysis, in particular a frequency analysis, from one of the mechanical measurement variables of pressure, differential pressure, power, vibration, solid-borne or airborne sound. On the basis of this, the rotational speed (n) of the driving machine is determined, from which in turn the operating point characterized by the power (P2) consumed by the work machine and/or by the output rate (Q) thereof is determined using the rotational speed/torque dependency (M(n)) of the asynchronous motor (52).