Variable-Volume Liquid Injection Chamber for Compact Thermoplastic Container Shaping
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Solution Overview
Problem
Existing liquid injection devices for forming thermoplastic containers are bulky due to the large cylinder required for high-pressure liquid injection, which is inefficient and not compact enough for practical use.
Innovation Solution
A compact liquid injection device with a variable-volume working chamber connected downstream of the pumping means, featuring a single liquid inlet and outlet orifice, an anti-reflux mechanism, and a motorized pump with a cylinder capacity less than the final container volume, allowing for efficient high-pressure liquid injection without the need for a large cylinder.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If a large cylinder is used for high-pressure liquid injection, then the liquid can be compressed to high pressures necessary for container shaping, but the device becomes bulky and inefficient
Solution Approach 1:
The injection system is divided into two independent stages: a first injection stage using a small cylinder at low pressure to fill the container, and a second injection stage using a pump at high pressure to compress the liquid for shaping. This segmentation allows each component to be optimized for its specific function, eliminating the need for a large cylinder that would be required to deliver both high pressure and large volume simultaneously.
Solution Approach 2:
The container is pre-filled with liquid at low pressure using the small cylinder before the high-pressure injection phase. This preliminary action ensures the container contains sufficient liquid volume, and then only a small additional volume is injected at high pressure to achieve the shaping effect, thereby avoiding the need for a large high-pressure cylinder.
2Volume of moving object
If a small displacement pump is used, then the device becomes more compact, but the pump must deliver liquid at substantially constant pressure to the variable-volume working chamber
Solution Approach 1:
The working chamber volume is made variable through a movable piston that can be positioned at different locations. This dynamic adjustment of chamber volume allows the small displacement pump to deliver liquid at substantially constant pressure while the chamber adapts its volume to match the injection requirements, resolving the conflict between compact pump size and pressure control ease.
Solution Approach 2:
The system uses feedback control where the position of the piston in the working chamber and the pressure conditions are monitored to regulate the pump operation. This ensures that the small displacement pump maintains substantially constant pressure delivery despite the variable volume requirements of the working chamber during the injection process.
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 device achieves efficient and compact high-pressure liquid injection, enabling the formation of thermoplastic containers with reduced size and complexity, while maintaining the ability to compress the liquid to high pressures necessary for shaping the container.
Implementation Method 1
pumping means for circulating the liquid in the supply line to the container with a first pressure
Implementation Method 2
compression means for temporarily raising the pressure of the liquid contained in the container to a second pressure higher than the first pressure
Data Source
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AI summary
The invention relates to a device (31) for injecting an incompressible, pressurized liquid into a container (18) made of a thermoplastic material so as to shape the container (18), the injection device (31) comprising: a pipe (30) for supplying the liquid, which is to connect a liquid source (40) to the container (18); pumping means (42) for causing the liquid to flow in the supply pipe (30) toward the container (18) at a first pressure (P1); and compression means (44) for temporarily raising the pressure of the liquid contained in the container (18) to a second pressure (P2) that is greater than the first pressure (P1), characterized in that the compression means (44) are formed by a work chamber (48), the volume of which is variable, and which is connected only to the supply pipe (30) between the pumping means (42) and the container (18).