Electromagnetic Force Generation for Dialysis Scale Plausibility
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Solution Overview
Problem
Existing blood treatment systems face challenges in performing a reliable plausibility check of the weighing system without interrupting the treatment, as current methods either require interruptions or cannot distinguish between flow interruptions and scale errors, and are prone to noise and vibration issues.
Innovation Solution
A device with a plunger and coil arrangement that applies a defined force to the load cell using a current source, allowing for continuous plausibility checking by evaluating the signal emitted by the load cell in relation to the applied force, enabling identification of errors without treatment interruption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a test weight is automatically applied to the weighing system for plausibility check, then measurement reliability is improved, but treatment availability deteriorates due to required interruptions and system vibrations are generated
Solution Approach 1:
The patent replaces the mechanical test weight application system with an electromagnetic force generation system. Instead of physically placing a test weight on the scale pan, the system uses a coil positioned near the load cell to generate electromagnetic forces that simulate weight changes. This substitution eliminates the need for mechanical intervention, allowing continuous testing during treatment without interruptions or vibrations.
Solution Approach 2:
The patent introduces an intermediary electromagnetic field between the test signal source and the load cell. The coil generates electromagnetic forces that act on the load cell's sensitive element, serving as an intermediary mechanism to apply test forces without direct mechanical contact. This intermediary approach allows plausibility checks to occur seamlessly during treatment.
2Measurement precision
If a test weight is placed on the weighing system for plausibility check, then measurement accuracy is improved, but noise and vibrations are generated affecting system stability
Solution Approach 1:
The patent substitutes mechanical weight placement with electromagnetic force generation. The coil positioned in proximity to the load cell generates controlled electromagnetic forces that directly influence the load cell's measurement element without requiring physical contact or mechanical movement. This eliminates vibrations and noise associated with placing test weights on the scale pan while maintaining measurement accuracy.
Solution Approach 2:
The patent extracts the harmful mechanical interaction (placing test weights on the pan) from the testing process. By removing the physical contact between test weights and the weighing pan, the system eliminates the source of vibrations and noise while preserving the essential function of applying known forces for plausibility verification.
3Productivity
If continuous plausibility checking is performed using the hose reel pump, then treatment availability is improved, but fault differentiation capability deteriorates due to insufficient delivery accuracy
Solution Approach 1:
The patent replaces the hose reel pump-based testing method with an electromagnetic force generation system. The coil can generate precisely controlled forces that directly challenge the load cell's measurement capability with known magnitudes. This substitution provides superior force control and measurement resolution compared to pump delivery rate variations, enabling clear differentiation between load cell faults and flow interruptions while maintaining continuous operation during treatment.
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
Enables continuous, reliable plausibility checking of the weighing system during treatment, distinguishing between errors and flow interruptions, and reducing noise and vibration, thus ensuring uninterrupted operation.
Implementation Method 1
at least one coil (4) having at least one cavity (4a) in which the plunger (3) is movably received, and at least one current source (5) which supplies the coil (4) with current at least temporarily, wherein the coil (4) or plunger (3) is arranged on the weighing system in order to apply a defined force to the load cell (2) when current flows through the coil (4)
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
The invention relates to an apparatus for testing a weighing system of a blood treatment device, in particular a dialysis machine, wherein the weighing system has at least one weighing cell. The apparatus comprises at least one plunger, at least one coil having at least one cavity, in which the plunger is movably accommodated, and at least one current source that energizes the coil, at least at times. The coil or the plunger are arranged on the weighing system in order to apply a defined force to the weighing cell whenever current flows through the coil. The invention further relates to a blood treatment device having such an apparatus, and to a method for testing a weighing system of a blood treatment device.