Contactless Thermal Flow Meter for Low-Rate Drug Pumps
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Solution Overview
Problem
Existing electric drug injection pumps face challenges in accurately measuring low flow rates without direct contact with the drug, leading to increased errors and decreased stability, and current technologies are not suitable for precise and accurate flow rate measurement.
Innovation Solution
A flow meter for electric drug injection pumps that measures flow rate using a temperature sensor part without direct contact with the drug, employing a heater and multiple temperature sensors disposed on the outer surface of the tube to measure temperature changes, allowing for precise and accurate flow rate determination through proportional, logarithmic, or exponential relationships.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If indirect type flow rate measuring device using CAM axis rotation is used, then device complexity is reduced, but measurement precision and stability deteriorate
Solution Approach 1:
The patent replaces the mechanical CAM axis rotation system with a thermal field-based measurement system. Temperature sensors and heaters are positioned around the tube to create thermal fields that interact with the flowing drug, enabling direct thermal measurement without mechanical contact. This substitution eliminates mechanical wear and complexity while achieving higher measurement precision through thermal field analysis.
Solution Approach 2:
The patent introduces temperature fields as an intermediary between the drug flow and the measurement system. Instead of directly measuring mechanical flow parameters, the system measures temperature changes in the thermal field caused by drug flow. This intermediary approach allows indirect measurement of flow rate through thermal field interactions, avoiding direct mechanical contact while maintaining measurement accuracy.
2Measurement precision
If sensor makes direct contact with fluid to measure flow rate, then measurement precision is improved, but reliability deteriorates due to drug contamination and sensor degradation
Solution Approach 1:
The patent uses the tube wall as an intermediary between the drug flow and the temperature sensors. The temperature sensors are positioned on the outer surface of the tube, measuring temperature changes that occur in the tube wall due to drug flow. This intermediary approach allows the sensors to measure flow-related temperature changes without direct contact with the drug, preventing contamination while maintaining measurement precision.
Solution Approach 2:
The patent replaces direct mechanical contact between sensors and fluid with a thermal field-based measurement system. Temperature sensors measure thermal field changes in the tube wall caused by drug flow, eliminating the need for sensors to be in direct contact with the drug. This substitution maintains measurement capability while preventing drug contamination and sensor degradation.
3Measurement precision
If heat signal measurement technology is used, then measurement precision is improved, but device complexity increases due to multiple sensors and heaters required
Solution Approach 1:
The patent divides the measurement system into multiple functional segments: heaters positioned at specific locations to create thermal fields, temperature sensors positioned to detect thermal changes, and a control unit to process measurements. This segmentation allows each component to perform its specific function efficiently while the modular structure manages overall system complexity through functional decomposition.
Solution Approach 2:
The patent designs the temperature sensors and heaters to serve multiple functions: they measure temperature changes, create thermal fields for measurement, and can potentially serve as flow indicators. This multi-functionality reduces the need for separate dedicated components for each function, thereby managing device complexity while maintaining high measurement precision.
4Adaptability or versatility
If low flow rate measurement is implemented, then adaptability is improved, but measurement precision deteriorates due to thermal noise and sensitivity issues
Solution Approach 1:
The patent positions temperature sensors and heaters at specific locations around the tube where thermal field interactions are most sensitive to flow rate changes. By optimizing the local arrangement of sensors and heaters, the system achieves enhanced sensitivity to low flow rates while minimizing thermal noise interference. This localized optimization enables accurate measurement across a wide flow range including very low flow rates.
Solution Approach 2:
The patent employs dynamic parameter adjustment in the control unit to compensate for thermal noise and sensitivity variations at low flow rates. The system can adjust measurement parameters, filtering thresholds, and calculation methods based on the detected flow regime, enabling accurate measurement across different flow conditions including very low flow rates while maintaining measurement precision.
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 precise and accurate measurement of flow rates from 0 to 100 mL/hr by utilizing temperature sensors and heaters on the outer surface of the tube, enhancing usability and convenience while maintaining sensor integrity and drug purity.
Implementation Method 1
The heater is positioned at one of the grooves, to supply a heat to a fluid passing through the tube
Implementation Method 2
The temperature sensor part is positioned at each of the grooves, to measure the temperature of the fluid passing through the tube
Data Source
AI summary
In a flow meter for an electric drug injection pump and a method for measuring a flow using the flow meter, the flow meter includes a lower case, an upper case and a temperature sensor part. A plurality of grooves and an extending groove are formed in the lower case. The grooves are spaced apart from each other. The extending groove extends along the grooves and a tube is positioned in the extending groove. The upper case faces the lower case and is combined with the lower case, to fix the tube. The heater is positioned at one of the grooves, to supply a heat to a fluid passing through the tube. The temperature sensor part is positioned at each of the grooves, to measure the temperature of the fluid passing through the tube. The tube is positioned to make contact with the heater and the temperature sensor part.