Inhaler Metering Valve Design for Gas-Lock-Free Dosing
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Solution Overview
Problem
Existing inhalers face issues such as inaccurate dosing due to gas lock formation in the metering chamber, difficulty in assembling internal components, and unreliable dose counting, along with potential damage from manual priming and tampering.
Innovation Solution
The inhaler features a metering valve with a communication path between the metering chamber and interior reservoir, allowing liquid from the reservoir to replace gas in the chamber, and a configuration that prevents manual priming by securing the cap housing, ensuring accurate dosing and preventing tampering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the mouthpiece cap is left open after inhalation, then the metering chamber communicates with atmosphere, but this results in gas lock formation and variance in active ingredients in subsequent doses
Solution Approach 1:
The patent extracts the harmful gas/air from the metering chamber by providing a communication path that allows liquid propellant to flow in and displace the gas. The gas is vented out through the same communication path, ensuring the chamber is primed with liquid before the next dose, thus eliminating gas lock while maintaining ease of use.
2Reliability
If manual priming is performed by removing the cap housing and firing multiple doses, then the metering chamber is sufficiently primed, but this is wasteful and may result in damage to the inhaler
Solution Approach 1:
The patent implements preliminary action by automatically priming the metering chamber with liquid propellant through the communication path before each dose is delivered. This eliminates the need for manual priming operations, preventing waste of medicament that would otherwise be consumed during manual priming attempts.
3Device complexity
If radial capillary ports are used for communicating substances, then the valve stem structure is simple, but this allows blowback leakage between the valve stem block and valve stem
Solution Approach 1:
The patent introduces an intermediary sealing arrangement between the valve stem and valve stem block. This intermediary structure prevents blowback leakage while maintaining the simplicity of the radial capillary port configuration, resolving the contradiction between structural simplicity and sealing 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
This configuration ensures accurate dosing by avoiding gas lock, simplifies assembly, and prevents damage by securing the cap housing, thereby enhancing reliability and user safety.
Implementation Method 1
a communication path between the metering chamber and interior reservoir, the communication path including an opening configured to permit flow between a transfer space inside the valve stem and the interior reservoir
Data Source
Figure 1A~1B
Figure 2
Figure 3
AI summary
An inhaler (10) for the inhalation of inhalable substances comprise: a canister (50) having an interior reservoir (84) containing pressurised inhalable substances including fluid; a metering valve (52) including a metering chamber (82) and a valve stem (54) defining a communication path between the metering chamber and the interior reservoir, the communication path (86) including an opening (106) configured to permit flow between a transfer space inside the valve stem and the interior reservoir, the interior reservoir being arranged for orientation above the metering chamber whereby gas such as air located within the metering chamber is replaced with liquid from the interior reservoir.