Pressure-Controlled Metering for Wide-Range Precise Dosing
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Solution Overview
Problem
Conventional metering systems for low-viscosity liquids and gases have limited flow rate ranges and are prone to pulsating flows and malfunctions, especially in the lower dosing range, and are sensitive to pressure differences, restricting their metering quantity range and precision.
Innovation Solution
A system utilizing a pressure control valve and mass flow sensor in a closed control loop, where the dosing quantity is regulated exclusively by setting the dosing pressure, independent of the pressure difference between inlet and metering pressures, allowing for a wide and precise dosing spectrum.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a positive displacement pump is used for dosing low-viscosity liquids, then the dosing volume can be controlled by pump speed and chamber volume, but the system produces pulsating flow and loses precision in the lower dosing range
Solution Approach 1:
The patent replaces the mechanical positive displacement pump system with a pressure-controlled valve system. Instead of using mechanical pistons or diaphragms to displace fluid, the invention uses a control valve regulated by a pressure controller and flow sensor to meter the liquid. This substitution eliminates the inherent pulsating flow and precision loss associated with mechanical pump components in the lower dosing range.
Solution Approach 2:
The patent implements a closed-loop feedback system using a flow sensor to monitor actual flow rate and a pressure controller to adjust the valve positioning accordingly. The flow sensor provides real-time feedback on the dosing rate, allowing the pressure controller to make continuous adjustments to maintain precise dosing. This feedback mechanism eliminates the open-loop control limitations of conventional pump systems.
2Quantity of substance
If a needle valve is used to adjust dosing quantity, then the dosing quantity can be set by needle position, but the dosing quantity fluctuates with pressure differential changes
Solution Approach 1:
The patent employs a closed-loop feedback system where a flow sensor continuously monitors the actual dosing quantity and feeds this information to a pressure controller. The pressure controller adjusts the control valve positioning in real-time to compensate for pressure differential fluctuations, maintaining stable dosing quantity despite changes in inlet or outlet pressure conditions.
Solution Approach 2:
The patent changes the controlling parameter from static needle position to dynamic pressure control. Instead of relying on a fixed mechanical needle position that is sensitive to pressure changes, the system uses a pressure controller to dynamically adjust the valve opening based on real-time pressure and flow conditions, making the dosing quantity independent of pressure differential variations.
3Quantity of substance
If the needle position is adjusted to change dosing quantity, then small dosing quantities can be achieved, but the adjustable dosing quantity range is very limited
Solution Approach 1:
The patent transitions from a static mechanical needle position system to a dynamic pressure-controlled valve system. The control valve can be positioned anywhere within its full travel range by varying the pressure control setpoint, allowing continuous and wide-range adjustment of dosing quantity. This dynamic control enables adaptation to both very small and very large dosing requirements within a single system configuration.
Solution Approach 2:
The patent changes the control parameter from limited mechanical needle position to variable pressure control. By adjusting the pressure control setpoint across a wide range, the system can achieve dosing quantities from very small to very large values. The pressure-controlled valve responds linearly and predictably to pressure changes, providing a broad and continuous dosing range that far exceeds the limited 1:10 to 1:20 range of conventional needle valves.
4Quantity of substance
If a positive displacement pump is used, then the dosing volume depends on pump speed and chamber volume, but the system is prone to malfunctions due to control valves
Solution Approach 1:
The patent replaces the mechanical positive displacement pump with a pressure-controlled valve system. This eliminates the mechanical components (pistons, diaphragms, mechanical check valves) that are prone to wear, leakage, and malfunction. The new system uses a control valve regulated by an electronic pressure controller and flow sensor, which has no moving mechanical parts in the fluid path and therefore higher reliability.
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 a large and reliable metering quantity range, with precise control of dosing quantities from very small to very large, maintaining consistency despite pressure fluctuations, and achieving reproducible dosing with minimal overshoot or undershoot.
Implementation Method 1
A flow sensor (3) is arranged in the inlet (10). The flow sensor (3) and the pressure control valve (4) form a closed control loop (6). A flow rate can be determined using the flow sensor (3).
Implementation Method 2
the dosing quantity being determined by the pressure difference between the metering pressure (p2) and the process pressure (p3)
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A system (1) for dosing a liquid or gaseous medium comprises a pressure control valve (4) and a flow sensor, wherein the pressure control valve (4) and the flow sensor form a closed control loop (6). The required dosing quantity is adjustable by controlling the dosing pressure (p2) using the pressure control valve (4).