Canister For A Metered Dose Inhaler And Method Of Producing Such Canister
Patent No. US2015320945 (titled "Canister For A Metered Dose Inhaler And Method Of Producing Such Canister") was filed by Presspart on Sep 20, 2013. The application was issued on Nov 12, 2015.
What is this patent about?
’945 is related to the field of pressurized canisters for metered dose inhalers (MDIs). These devices are standard for treating respiratory conditions like asthma, requiring a container that can safely store liquefied propellants and active pharmaceutical ingredients under significant internal pressure while remaining lightweight and cost-effective for mass production.
The underlying idea behind ’945 is that the structural requirements for the sidewall and the bottom wall of a canister are not identical, allowing for a strategic reduction in material without compromising safety. By specifically thinning the sidewall relative to the bottom wall, the invention reduces the total amount of metal required—and thus the carbon footprint and manufacturing cost—while maintaining the necessary burst pressure resistance through a thicker, reinforced base.
The claims of ’945 focus on a canister geometry where the tubular sidewall is manufactured to be thinner than the bottom wall. Specifically, the independent claim protects a configuration where the bottom wall thickness is maintained between 0.25 and 0.47 mm, while the sidewall is reduced to a range of 0.15 to 0.42 mm, featuring a central inwardly domed portion at the base.
In practice, this differential thickness is achieved through a combination of deep drawing and wall ironing. Starting from a metal blank, the cup shape is formed, and then the sidewalls are mechanically stretched and thinned while the base retains more of its original gauge. This process creates a vessel that is structurally optimized, placing the mass where the mechanical stress is highest during potential pressure spikes or drop impacts.
This approach differs from traditional MDI canisters, which have historically utilized a uniform wall thickness of approximately 0.47 mm. By moving away from a constant thickness, the invention achieves significant material savings—up to 46% in some embodiments—without falling below the critical 220 psi burst pressure threshold required by international safety regulations for pressurized inhalers.
How does this patent fit in bigger picture?
Technical Landscape
In the early 2010s when ’945 was filed, the production of pressurized delivery vessels for respiratory therapies was characterized by deep-drawing processes that yielded containers with substantially uniform wall thicknesses. At a time when canisters were typically implemented using standardized aluminum or magnesium alloys to meet strict safety regulations, engineering constraints commonly dictated a wall thickness of approximately 0.47 mm throughout the entire structure to ensure structural integrity under high internal pressures. Because these systems relied on the inherent strength of a uniform material gauge to prevent catastrophic failure, reducing material volume while maintaining a specific burst pressure threshold was non-trivial, often resulting in high energy consumption and material waste during mass manufacturing.
Prosecution Position
The disclosed invention achieves a meaningful technical advancement through an architectural shift in the distribution of material thickness between the structural components of a metered dose inhaler canister. By integrating a differential thickness profile where the tubular sidewall is significantly thinner than the central domed portion of the bottom wall, the design overcomes the technical constraint of balancing material reduction with high-pressure safety requirements. This structural solution is further enhanced by an annularly closed inward depression region in the bottom wall, which provides localized reinforcement at the transition zone. The resulting technical effect is a canister that maintains necessary burst pressure characteristics and safety inversion capabilities while substantially reducing the total mass of metal required, thereby decreasing the energy intensity and carbon footprint of the manufacturing process.
Claims
The patent contains a total of 15 claims, with claim 1 serving as the sole independent claim. This independent claim focuses on the structural configuration of a metered dose inhaler canister, specifically defining a pressurized interior cavity where the bottom wall is thicker than the sidewall and includes a central inwardly domed portion. The dependent claims serve to further specify the geometric shape of the sidewall, provide narrower numerical ranges for the wall thicknesses, detail the specific curvature and regions of the bottom wall, and describe methods for manufacturing the canister through deep drawing and ironing processes.
Key Claim Terms New
Definitions of key terms used in the patent claims.
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US2015320945
- Application Number
- US201314429570
- Filing Date
- Sep 20, 2013
- Publication Date
- Nov 12, 2015
- External Links
- Slate, USPTO , Google Patents