Pump Flow Measurement by Speed Extrapolation at Low Flow Rates
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for determining the through-flow quantity in fluid delivery systems, particularly at low flow rates, are inaccurate due to systematic errors caused by bearing friction and electrical component consumption, leading to significant errors in determining the actual flow quantity.
Innovation Solution
The method involves increasing the motor speed to a higher second speed, determining the through-flow quantity at this speed, and then extrapolating this value 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
1Ease of operation
If the through-flow quantity is determined directly from motor power and speed at low flow rates, then the determination process is simple, but the measurement precision deteriorates due to systematic errors from bearing friction and electrical component consumption
Solution Approach 1:
The patent applies preliminary action by performing a speed extrapolation calculation before finalizing the through-flow quantity determination. The control device calculates what the through-flow quantity would be at the actual operating speed based on measurements taken at a different speed, thereby compensating for systematic errors before the final measurement is recorded.
Solution Approach 2:
The patent changes the operating parameter (motor speed) to a different value for measurement purposes, then uses extrapolation to determine the through-flow quantity at the original speed. This parameter change allows the system to operate in a range where systematic errors are minimized while still providing accurate low-speed measurements through calculation.
2Measurement precision
If the motor speed is increased to a second speed for measurement, then the measurement precision improves, but the productivity decreases due to interruption in normal fluid delivery
Solution Approach 1:
The patent implements periodic action by temporarily changing the motor speed only for the brief duration needed to perform the through-flow quantity measurement, then immediately restoring the original speed. This periodic speed change allows accurate measurement without sustained interruption to normal fluid delivery operations.
Solution Approach 2:
The patent rushes through the speed change and measurement process as quickly as possible, minimizing the time the system spends at the second speed. The control device performs the speed adjustment, measurement, and restoration in rapid succession, thereby reducing the impact on productivity while still achieving accurate through-flow quantity determination.
Data Source
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 including an electromotor and the electromotor being operated at a first speed when the electromotor is in operation and the through-flow quantity being determined from a measured motor power and the speed. The method includes (i) increasing the first speed to a second speed which is greater than the first speed; (ii) determining a second through-flow quantity at the second speed from the motor power and the second speed; (iii) determining a third through-flow quantity from the second through-flow quantity by extrapolation of the second speed to the first speed, wherein the third through-flow quantity is the target variable; and, (iv) reducing the speed back to the first speed once the second through-flow quantity has been determined.