Displacement Pump Partial Stroke Delivery for Dialysis Accuracy
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Solution Overview
Problem
Existing displacement pumps in dialysis machines face challenges in achieving high accuracy for small delivery volumes, particularly in the range of 200 μl to 300 μl, due to dependence on input and output pressure and time drift, requiring additional apparatus for precise dosing.
Innovation Solution
A control unit actuates the pump to suck in a volume exceeding the desired delivery volume during a single suction stroke and discharges it in multiple partial volumes, allowing for precise delivery by approximating the desired volume through partial strokes, which can be calibrated for improved accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a displacement pump is used to deliver small volumes (200-300 μl), then the device can be compact with fewer pumps, but the delivery accuracy deteriorates due to dependence on input/output pressure and time drift
Solution Approach 1:
The invention segments the delivery process into multiple partial delivery strokes within a single suction stroke. The pump sucks in a large volume and then delivers it in multiple smaller controlled portions, each with its own partial delivery stroke. This segmentation allows the use of a single pump for small volume deliveries while maintaining accuracy by breaking down the delivery into controllable segments rather than relying on single-stroke precision.
Solution Approach 2:
The invention employs partial or excessive action by having the pump suck in a volume that exceeds the desired delivery volume, then delivering only the necessary portion through controlled partial delivery strokes. This allows the pump to operate in a regime where it can achieve better accuracy control over smaller portions of the total volume, rather than attempting to deliver the entire volume in a single stroke.
2Device complexity
If the pump delivers volume in a single stroke, then the device structure is simple, but the delivery accuracy for small volumes deteriorates due to pressure and time drift
Solution Approach 1:
The invention segments the delivery process into multiple partial delivery strokes within a single suction stroke. The pump sucks in a large volume and then delivers it in multiple smaller controlled portions, each with its own partial delivery stroke. This segmentation allows the use of a single pump for small volume deliveries while maintaining accuracy by breaking down the delivery into controllable segments rather than relying on single-stroke precision.
Solution Approach 2:
The control unit monitors and controls the pump operation to ensure accurate delivery. By controlling multiple partial delivery strokes and monitoring the delivery process, the system can compensate for pressure variations and time drift, ensuring that the desired volume is delivered with high accuracy despite the complexity of multi-stroke operation.
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
This method enables high accuracy in delivering small volumes with a single pump, reducing the need for multiple pumps and ensuring precise dosing across a range of delivery volumes, from 200 μl to 300 μl and beyond, by using a larger suction volume divided into smaller partial volumes.
Implementation Method 1
The pump is designed and arranged such that it creates a pressure differential between the suction side and the discharge side
Data Source
AI summary
A device and a method for delivering fluids, preferably for delivering medical fluids, such as in the field of dialysis, include at least one pump designed as a displacement pump and at least one control unit that controls the operation of the pump. The pump is actuated by the control unit such that during a suction stroke in a first operating condition the pump takes in a volume exceeding a desired delivery volume for the purpose of discharging a desired delivery volume, and discharges portions of the volume taken in by performing a plurality of partial delivery strokes in the form of partial volumes which are smaller than the volume taken in.