Positive Displacement Pump Flow Control With Timed Sensor Feedback
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing positive displacement pumps face challenges in maintaining a constant flow rate due to tubing changes during operation, which affect calibrated settings, and conventional control techniques struggle with latency, pulsation, and noisy flow sensor signals, leading to inaccuracies.
Innovation Solution
A control method that includes flow control cycles accounting for movement, wait, and measurement times to stabilize the flow rate, using a flow sensor to adjust pump speed and compensate for tubing and fluid characteristics, with a pump controller determining control cycles to achieve a targeted flow setpoint.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If conventional control techniques are used to control pump speed, then the pump can operate continuously, but the flow rate measurement accuracy deteriorates due to latency, pulsation, and noisy sensor signals
Solution Approach 1:
The system performs preliminary actions by determining predicted movement time and predicted wait time before making control decisions. The controller calculates when the pump will reach target speed and when flow rate will stabilize, then waits for this predicted stabilization time before measuring flow rate, thereby avoiding noisy transient signals and achieving accurate measurement during continuous operation
Solution Approach 2:
The system uses feedback from the flow sensor to continuously monitor actual flow rate and compare it with the target flow rate. Based on this feedback and the predicted wait time calculation, the controller adjusts pump speed to maintain accurate flow rate control despite continuous operation, tubing changes, and fluid characteristic variations
2Productivity
If pump speed is adjusted rapidly to reach target flow rate, then productivity improves, but flow rate stability deteriorates due to latency between speed change and flow sensor response
Solution Approach 1:
The controller performs preliminary calculation of predicted movement time (time for pump to reach target speed) and predicted wait time (time for flow rate to stabilize after speed change). This allows the system to rapidly adjust pump speed for productivity while knowing exactly when to expect flow rate stabilization, thereby maintaining both speed and stability
Solution Approach 2:
The system dynamically adjusts the measurement timing based on calculated predicted wait times. Rather than using fixed delays, the controller adapts the waiting period before flow rate measurement based on the specific pump speed changes and system characteristics, enabling rapid response while maintaining flow rate stability
3Adaptability or versatility
If tubing properties change during operation, then adaptability improves as the system can handle different conditions, but manufacturing precision deteriorates as calibrated settings become inaccurate
Solution Approach 1:
The system uses continuous feedback from the flow sensor combined with predicted wait time calculation to detect when actual flow rate deviates from expected values due to tubing changes. The controller adjusts pump speed based on this feedback to maintain precise flow rate control even as tubing properties change during operation
Solution Approach 2:
The system adapts to tubing changes by dynamically adjusting pump operating parameters (speed, acceleration, wait time) based on measured flow rate feedback. When tubing wear or property changes cause flow rate deviations, the controller modifies operational parameters to compensate and maintain manufacturing precision
Data Source
Figure 1A~1B
Figure 2
Figure 3
AI summary
Aspects are provided for positive displacement pumps and methods and systems for controlling such pumps for dispensing at a flow rate based on a downstream flow sensor. A pump controller determines a targeted motor speed for a flow rate set point based on a flow rate function. The pump controller determines a predicted movement time for a motor of the pump to change from a current motor speed to the targeted motor speed, a predicted wait time to reach a flow rate corresponding to the targeted motor speed, and a measurement time after the wait time. The pump controller controls the positive displacement pump according to consecutive control cycles, each control cycle includes a pump movement sub-cycle, a wait sub-cycle, and a measurement sub-cycle. The pump controller determines a measured flow rate during the measurement sub-cycle. A subsequent control cycle is based on the measured flow rate.