Pump Current Monitoring for Dialysis Balancing Chambers
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Solution Overview
Problem
Existing systems for monitoring the electrically operated pumps in extracorporeal blood treatment devices face challenges in reliably detecting the periodically occurring increase in pump current, which is influenced by factors like pump aging and delivery rate, leading to inaccurate control signals.
Innovation Solution
A monitoring device that continuously adjusts a predetermined limit value for pump current by calculating it from minimum and maximum voltage measurements, allowing for reliable detection of current increases without the need for recalibration, and incorporates a timer to suppress interference pulses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pump current is monitored using a fixed predetermined limit value, then the system is simple to operate, but the detection reliability decreases due to pump aging and delivery rate changes
Solution Approach 1:
The patent applies dynamics by continuously adapting the predetermined limit value based on the actual operating conditions. Instead of using a fixed threshold, the system dynamically adjusts the limit value according to the measured pump current characteristics, thereby maintaining high detection reliability despite pump aging and delivery rate changes.
Solution Approach 2:
The patent implements feedback by continuously monitoring the pump current and using this information to adjust the predetermined limit value. The system measures the actual pump current, compares it with the limit value, and adapts the limit value based on the observed current characteristics, creating a closed-loop control that improves detection reliability.
2Measurement precision
If the pump current monitoring threshold is set to detect all current increases, then detection sensitivity is high, but false triggering increases due to interference pulses
Solution Approach 1:
The patent applies preliminary action by measuring and storing the minimum and maximum pump current values before establishing the predetermined limit value. This preliminary characterization of the current range allows the system to set an appropriate threshold that distinguishes genuine switching events from interference pulses, preventing false triggering while maintaining detection sensitivity.
Solution Approach 2:
The patent uses partial action by selectively responding to current increases that exceed the dynamically adjusted limit value while ignoring smaller fluctuations. The system applies a threshold-based filtering approach that captures the essential switching events without reacting to every minor current variation, thereby avoiding false positives.
3Speed
If the pump current is continuously monitored with a fixed limit value, then the system response is fast, but incorrect control signals are generated due to pump aging
Solution Approach 1:
The patent implements self-service by enabling the system to automatically adjust its own operating parameters (the predetermined limit value) based on its measured performance characteristics. The monitoring device characterizes the pump current itself and uses this self-generated information to adapt the detection threshold, eliminating the need for external recalibration or manual intervention while maintaining fast response times.
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
Ensures high reliability and security in generating control signals for switching balancing chamber operations, unaffected by pump aging or delivery rate changes, and prevents incorrect adjustments due to interference pulses.
Implementation Method 1
the time course of the pump current is monitored to control the electrically operated pump and the valves in the dialysis fluid system
Implementation Method 2
each of which is separated into two balancing chamber halves by a flexible partition. By alternately filling and emptying the two chamber halves, exactly the same volumes of dialysis fluid can be fed into the dialyzer and removed from the dialyzer
Data Source
Figure 1
Figure 2
AI summary
The invention relates to a device and a method for monitoring an electrically operated pump arranged in a liquid system, in particular a dialysis liquid system, of an extracorporeal blood treatment device arranged, in particular an electric pump for delivering dialysis liquid. The device (30) according to the invention for monitoring is characterized by an evaluation unit (30b) comprising means for continuously determining the predefined threshold value, to which the pump flow or a quantity correlating with the pump flow are compared. In order to detect a periodically occurring increase of the pump flow or the quantity correlating with the pump flow, the pump flow or the quantity correlating with the pump flow is compared to the continuously calculated threshold value. Since the predefined threshold value is continuously adjusted, the aging of the pump or the delivery rate thereof has no influence on generating the control signal. A readjustment or calibration of the pump is therefore not necessary. Thus, the control signal is generated with a high amount of certainty and great reliability.