Method for determining a through-flow quantity in a fluid delivery system, method for determining an amount of energy of a delivery fluid, fluid delivery system and pump
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Solution Overview
Problem
Existing methods for determining the through-flow quantity in fluid delivery systems, particularly at low flow rates, suffer from significant systematic errors due to bearing friction and electrical component consumption, leading to inaccurate measurements.
Innovation Solution
Increasing the motor speed to a higher second speed, determining the through-flow quantity at this speed, and then extrapolating it back to the original speed to minimize systematic errors, allowing for a more accurate calculation of the target through-flow quantity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the through-flow quantity is determined directly from motor power and speed at low flow rates, then the measurement process is simple, but the measurement precision deteriorates due to systematic errors from bearing friction and electrical component consumption
Solution Approach 1:
The patent changes the operating parameter (motor speed) to a higher value during measurement to reduce the relative impact of systematic errors. By measuring at increased speed where hydraulic power dominates over friction and electrical losses, the measurement precision improves. After measurement, the speed is reduced back to the original operating speed, thus resolving the contradiction between simple measurement process and precise measurement results.
2Measurement precision
If the motor speed is increased to a second speed for measurement, then the measurement precision improves, but the loss of time increases due to speed adjustment and extrapolation process
Solution Approach 1:
The patent replaces direct mechanical measurement at low speed with a computational approach. By measuring at high speed and using extrapolation algorithms to calculate the equivalent low-speed flow rate, the system achieves high precision without requiring actual low-speed measurement. This substitution of mechanical measurement with computational calculation reduces the time penalty while maintaining measurement precision.
3Measurement precision
If the speed is increased to a second speed for accurate measurement, then the through-flow quantity determination becomes more accurate, but the use of energy increases during the measurement process
Solution Approach 1:
The patent applies partial excessive action by temporarily increasing the motor speed beyond the normal operating speed solely for the purpose of measurement. The excessive speed increase is limited to the measurement interval and immediately reversed after measurement completion. This partial excessive action achieves high measurement precision while minimizing the energy penalty, as the high-speed state is maintained only briefly during measurement rather than continuously.
Data Source
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AI summary
A method for determining a through-flow quantity in a fluid delivery system, in which a fluid is delivered by a pump, the pump comprising an electromotor and the electromotor being operated at a first speed (n1) when said electromotor is in operation and the through-flow quantity (Q) being determined from a measured motor power (P) and the speed (n), said method comprising : - increasing the first speed (n1) to a second speed (n2) which is greater than the first speed (n1); - determining a second through-flow quantity (Q(n2)) at the second speed (n2) from the motor power (P(n2)) and the second speed (n2); - determining a third through-flow quantity (Q*(n1)) from the second through-flow quantity (Q(n2)) by extrapolation of the second speed (n2) to the first speed (n1), wherein the third through-flow quantity (Q*(n1)) is the target variable; and, - once the second through-flow quantity (Q(n2) has been determined, reducing the speed (n) back to the first speed (n1).