Gas Injection Valve for Stable Foam Structure in Plastic Metering
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Solution Overview
Problem
Existing plastic metering devices face challenges in maintaining consistent foam structure quality due to fluctuations in mixing chamber pressure during discontinuous metering, and existing gas loading devices are inefficient and prone to contamination.
Innovation Solution
A valve device comprising a pressure regulating valve and a flow regulator, where the pressure regulating valve maintains constant pressure at the outlet of the flow regulator, allowing for precise control of air injection into the mixing chamber, thereby ensuring consistent foam structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If gas is injected directly into the liquid plastic component via a gas loading ring, then the plastic component can be loaded with gas, but the process is time-consuming and prone to contamination or blockages during discontinuous operation
Solution Approach 1:
The invention extracts the gas injection function from the liquid flow path by using a separate gas injection line that introduces gas above the liquid level in the pressure vessel, avoiding direct contact between gas and liquid plastic components during loading, thereby eliminating contamination risks while maintaining efficient gas loading
Solution Approach 2:
The invention introduces an intermediary gas injection mechanism that mediates between the gas source and the plastic component, using a controlled injection system with valve devices to regulate gas introduction without allowing direct interaction between gas flow and liquid plastic, thus preventing blockages and contamination
2Stress or pressure
If compressed air is fed into the pressure vessel to maintain pressure level, then the pressure can be kept constant, but the device complexity increases with multiple valve devices
Solution Approach 1:
The invention merges the pressure regulation function with the gas injection function by integrating a pressure regulating valve into the gas injection line, allowing a single valve device to perform both gas metering and pressure control tasks, thereby reducing overall device complexity while maintaining pressure stability
Solution Approach 2:
The gas injection valve device is designed with multi-functionality, serving both to inject gas into the pressure vessel and to regulate pressure levels through integrated pressure regulation capability, eliminating the need for separate pressure control mechanisms
3Manufacturing precision
If air is bound in dissolved form in polyol before entering mixing chamber, then foam structure can be promoted, but the extent of air bubbling out varies with mixing chamber pressure fluctuations
Solution Approach 1:
The invention applies preliminary action by pre-loading the polyol with a controlled amount of dissolved air at constant pressure conditions before the plastic components enter the mixing chamber, ensuring that the gas loading occurs under stable pressure conditions that prevent excessive bubbling during subsequent mixing chamber pressure fluctuations
Solution Approach 2:
The invention controls the gas loading process by maintaining constant pressure parameters during air dissolution in the pressure vessel, and by using a flow regulator to precisely control the gas flow rate, thereby optimizing the dissolved air content in polyol to achieve consistent foam structure despite mixing chamber pressure variations
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
The valve device provides precise control over air injection, resulting in consistent and high-quality foam structures in the plastic metering process, even during discontinuous operation.
Implementation Method 1
The actuator position adjusts itself automatically based upon the prevailing force conditions. For example, a fixation can be made possible by a balance between the pressure prevailing in the valve chamber and the pressure built up by the piston unit.
Implementation Method 2
The flow regulator has constant pressure conditions at the inlet and outlet, which makes it possible to provide a very precise flow.
Implementation Method 3
When the polyol enters the mixing chamber and the mixing chamber pressure is below the saturation pressure of the dissolved air, the air bubbles out, forming small air bubbles. These air bubbles form nuclei for the foam cells.
Data Source
AI summary
The invention relates to a valve device (50) for injecting gas (4) into a mixing chamber (11) of a plastic metering device (1) in order to load at least one component (2) located in the mixing chamber (11) with the gas, comprising a pressure regulating valve (51) and a flow regulator (52), wherein an inlet (56) of the pressure regulating valve (51) is connected to an outlet (55) of the flow regulator (51), and an outlet (71) of the pressure regulating valve (51) is suitable for opening preferably directly into the mixing chamber (11). The pressure regulating valve (51) has a valve chamber (57), an actuator (58) which can be moved in the valve chamber (57), and a piston unit (59) which is coupled to the actuator (58) and by means of which an axial position of the actuator (58) can be fixed on the basis of a pressure in the valve chamber (57). The invention additionally relates to a metering device (1) for metering out a foamed and foamable plastic (5) in a discontinuous manner, comprising such a valve device (50).