Soft Mist Inhaler Pressure-Relief Valve for Leak-Free Dosing
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Solution Overview
Problem
Existing soft mist inhalers face issues with improper collapsibility of containers due to material and friction resistances, leading to under-pressure, gas bubble formation, and underdosing, necessitating wasteful overfills to compensate.
Innovation Solution
A pressure-release valve at the metering pressure chamber outlet is designed to open at a pressure about 20-50% above the cartridge gauge pressure, minimizing fluidic friction losses and ensuring reliable operation by referencing cartridge pressure dynamics rather than the operating pressure during the atomizing stroke.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a collapsible container is used to store and transfer liquid formulation, then the device can be portable and multi-dose, but material elasticity and friction resistances prevent proper collapsibility leading to under-pressure and gas bubble formation
Solution Approach 1:
The patent replaces the mechanical collapsible container system with a pressurized container system. Instead of relying on material collapsibility to drive liquid flow, the invention uses a separate pressurization mechanism (spring-loaded piston or gas reservoir) to apply pressure to the liquid formulation, ensuring reliable and complete dose delivery without gas bubble formation.
Solution Approach 2:
The patent introduces a pressurization intermediary (spring-loaded piston or gas reservoir) between the liquid formulation and the metering pump. This intermediary transfers pressure to the liquid in a controlled manner, overcoming friction resistances and ensuring complete container collapse without creating under-pressure conditions that would cause gas bubble formation.
2Reliability
If overfilling is used to compensate for under-pressure and incomplete container collapse, then dosing reliability improves, but device complexity and waste increase
Solution Approach 1:
The patent incorporates a pressure-regulated valve system that provides feedback control for liquid flow from the container to the metering pump. The valve responds to pressure changes in the container, automatically regulating flow to ensure complete emptying without overfilling, thereby maintaining dosing reliability while simplifying the overall system.
3Reliability
If non-return valve seals at high pressure are used to prevent backflow, then liquid containment improves, but gas bubbles form during priming due to insufficient pressure difference
Solution Approach 1:
The patent implements a priming mechanism that performs preliminary action before normal operation. The system pre-pressurizes the container and ensures proper liquid filling of the metering pump chamber before the actual dosing cycle begins, preventing gas bubble formation during the priming stroke while maintaining high-pressure sealing during operation.
4Reliability
If high-pressure atomizing stroke is used to produce fine mist, then inhalable fraction increases, but pressure management complexity increases due to need for precise timing and sealing
Solution Approach 1:
The patent employs periodic action through a reciprocating metering pump mechanism that alternates between a priming stroke (low pressure, filling the chamber) and an atomizing stroke (high pressure, delivering the dose). This periodic cycle, controlled by a ratchet and pawl mechanism, simplifies pressure management by clearly separating the filling and delivery phases, reducing the need for complex continuous pressure control.
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 enhances the reliability and efficiency of the inhaler by preventing leakage and ensuring consistent dosing, reducing mechanical complexity, and minimizing user misuse through improved pressure management.
Implementation Method 1
A pressure-release valve at the metering pressure chamber outlet is designed to open at a pressure about 20-50% above the cartridge gauge pressure
Implementation Method 2
a high-pressure pump with metering chamber with a priming stroke and a high-pressure atomizing stroke
Implementation Method 3
an atomizer connected to the chamber outlet... discharging the metered quantity of fluid under pressure through an atomizing means
Data Source
Figure 1
Figure 2
Figure 3a~3b
AI summary
A soft mist inhaler (1), comprising a continuously pressurized collapsible container (6), a high-pressure pump (4) with a metering chamber (16), and an atomizer (18) connected to the outlet of the metering chamber (16), wherein the collapsible container (6) is connected to an inlet of the metering chamber (16) via a liquid passageway (22) to allow liquid flow from the collapsible container (6) to the metering chamber (16) during a priming stroke, should be designed high reliability in avoiding leakage via the nozzle in a particularly simple design. According to the invention this is achieved with a pressure-relief valve (34) provided in the connection between the metering chamber (16) and the atomizer (18), having an opening pressure of not more than 150% of the gauge pressure in the container (6).