Enhanced Eductor Design for Breath-Actuated Inhalers
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Solution Overview
Problem
Breath-actuated pressurized metered dose inhaler (BApMDI) devices often require more energy than a normal human breath to actuate, posing challenges for users with compromised lung function or adolescents, as the energy needed to trigger the device exceeds what can be applied by these individuals.
Innovation Solution
An enhanced eductor element with a protrusion or modification member in the constriction zone surrounding the inlet apex, which increases siphon pressure drop without significantly increasing the pressure drop across the eductor, allowing for reduced inspiratory flow rates needed to trigger the device, facilitating medicament delivery for younger patients and those with compromised lung function.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If the constriction zone diameter is reduced to increase siphon pressure drop, then the siphon pressure drop increases, but the pressure drop across the eductor increases and flow rate decreases
Solution Approach 1:
Rather than reducing the overall constriction zone diameter, the invention adds a localized modification member at the inlet apex. This approach concentrates the siphon-enhancing effect at a specific location without reducing the general cross-sectional area available for flow, thereby maintaining flow rate while increasing siphon pressure drop.
Solution Approach 2:
The modification member segments the constriction zone into distinct functional regions: the modification member itself generates siphon pressure, while the surrounding constriction zone maintains flow passage. This segmentation allows independent optimization of siphon performance and flow characteristics.
2Stress or pressure
If the modification member size is increased to further increase siphon pressure drop, then the siphon pressure drop increases, but the pressure drop across the eductor increases significantly
Solution Approach 1:
The invention optimizes the modification member dimensions as specific parameters, with the height ratio constrained to 0.1-0.5 times the constriction zone radius. This parameter optimization ensures sufficient siphon pressure generation while preventing excessive pressure drop across the eductor, achieving the desired balance through controlled dimensional relationships.
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 enhanced eductor design significantly increases siphon pressure drop while maintaining low pressure drop across the eductor, enabling actuation with a normal human breath, thus improving the usability of BApMDI devices for patients with compromised lung function or adolescents.
Implementation Method 1
a venturi having a flow path that narrows in a constriction zone and serves to increase the local velocity of the flow of inspiratory breath to create a siphon
Implementation Method 2
introduction of a protrusion or structure into the constriction zone surrounding the inlet apex of the siphon of a conventional eductor significantly increases the siphon pressure drop as a function of flow rate
Data Source
AI summary
The present invention provides for an enhanced eductor element that significantly increases the amount of pressure generated at the siphon tube without significantly increasing the flow resistance through the eductor. The invention further provides for breath-actuated inhalation devices comprising the enhanced eductor element as an actuation mechanism.