Liquid Discharge Piston Inlet Closure for Precise Dosing
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Solution Overview
Problem
Existing discharge devices for liquid media lack precision in dispensing a metered quantity of liquid medicaments, as the start and end of the dispensing stroke are not clearly defined, leading to inconsistent dosing.
Innovation Solution
A discharge device with a piston that enters an undersized inlet opening to precisely control the start of the delivery stroke, featuring a pressure-controlled outlet valve and a tapered enlargement area that connects to a low-pressure area, ensuring precise dosing and minimizing contamination risk through a controlled ventilation path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional discharge device with a piston is used, then the device can discharge liquid media, but the dosing precision is insufficient because the start and end of the dispensing stroke are not clearly defined
Solution Approach 1:
The inlet opening is designed to be slightly smaller than the piston cross-section, so that the piston automatically closes the inlet opening as soon as it enters, without requiring additional actuation. This preliminary design ensures that the start of the pumping stroke is precisely defined the moment the piston enters the pump chamber, eliminating delays and improving dosing precision.
Solution Approach 2:
The pressure-controlled outlet valve uses pressure feedback from the pump chamber to automatically control the discharge process. When the predetermined pressure is reached during the piston stroke, the valve automatically opens to discharge the medium, and closes when pressure drops below the threshold, creating a self-regulating system that ensures consistent metered quantity.
2Measurement precision
If the inlet opening is made smaller to improve sealing, then dosing precision improves, but the device complexity increases due to the need for precise dimensional matching
Solution Approach 1:
Instead of making the entire piston and inlet opening system highly complex with multiple sealing elements, the invention applies a simple local quality solution: the inlet opening is uniformly slightly smaller than the piston cross-section. This local dimensional difference creates the desired sealing effect without requiring complex mechanisms, maintaining overall device simplicity while achieving precise inlet closure.
3Measurement precision
If a pressure-controlled outlet valve is added to improve dosing precision, then the metering accuracy improves, but the device complexity increases
Solution Approach 1:
The pressure-controlled outlet valve is designed to operate autonomously based on the pressure conditions in the pump chamber. It automatically opens when the predetermined pressure is exceeded and closes when pressure falls below the threshold, without requiring external control mechanisms, actuators, or complex timing systems. This self-service operation adds minimal complexity while significantly improving discharge quantity control and dosing precision.
4Measurement precision
If the piston stroke is made shorter to improve dosing precision, then the metering accuracy improves, but the productivity decreases
Solution Approach 1:
The pressure-controlled outlet valve ensures continuous and complete discharge of the medium during the piston stroke. By automatically opening at the predetermined pressure point and remaining open until pressure drops below the threshold, the valve ensures that no medium is left undischarged, maximizing the useful action during each stroke. This allows shorter strokes to be fully utilized, maintaining productivity while improving 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
The solution enables precise dosing of the liquid medium by clearly defining the start and end of the dispensing stroke, preventing medium escape and contamination, while maintaining airtightness and bubble-free filling.
Implementation Method 1
The pressure-controlled outlet valve opens when a first predetermined pressure is exceeded on its inlet side and closes when the pressure on its inlet side falls below a predetermined threshold
Implementation Method 2
the piston, which is usually connected to a handle, is moved within the pump chamber. This reduces the volume of the pump chamber. As the volume decreases, the medium is forced out of the pump chamber through the outlet opening
Data Source
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AI summary
A discharge device (1) for discharging liquid media is described, comprising a pump chamber (7) having an inlet opening (11) and an outlet opening (13), and a piston (8) that is slidable within the pump chamber (7). The discharge device is designed to allow for highly accurate metering of the medium. For this purpose, the piston (8) has an extension (17) that enters the inlet opening (11) after a predetermined stroke of the piston (8).