Dose Counter With Angled Teeth For Inhaler Reliability
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Solution Overview
Problem
Existing dose counters and indicators for pressurized metered dose inhaler (pMDI) devices are complex, costly, and prone to undercounting, requiring multiple mechanical parts and tight dimensional tolerances, which can lead to reliability issues and increased costs.
Innovation Solution
A dose indicator/counter with a simplified design featuring a chassis with a displacement portion and indexable display units, utilizing a drive tooth and indexing teeth with angled engagement surfaces to ensure reliable interaction, reducing the number of components and enhancing robustness, allowing for accurate counting of hundreds of doses within a compact and cost-effective structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple mechanical parts are used in dose counters, then the counting function can be achieved, but the device complexity increases and assembly becomes difficult
Solution Approach 1:
The patent combines multiple counting functions into a single integrated mechanism. The drive gear engages with both the units display wheel and the tens display wheel through a unified tooth engagement system, eliminating the need for separate complex mechanical assemblies for each counting function. This merging reduces the number of parts while maintaining reliable dose counting capability.
2Reliability
If tight dimensional tolerances are required, then the mechanical parts can interact reliably, but manufacturing cost increases
Solution Approach 1:
The patent modifies the engagement parameters of the mechanical teeth by introducing angled engagement surfaces instead of traditional radial tooth profiles. The drive tooth and display unit teeth engage at an optimized angle that increases the contact area and distributes mechanical loads more evenly. This parameter change allows for relaxed dimensional tolerances while maintaining reliable interaction between parts.
3Volume of moving object
If a compact design is implemented, then the dose counter fits within existing actuators, but the number of doses that can be counted is limited
Solution Approach 1:
The patent segments the counting display into two independent but coordinated display units: a units wheel showing individual doses (0-9) and a tens wheel showing groups of ten doses (0-19). Each display unit has its own gear mechanism that can be compactly arranged. The drive gear transfers rotation from the canister to both display units through a compact gear train, enabling counting of up to 200 doses within a small volume that fits existing actuator designs.
Data Source
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Figure 2
Figure 3a~3b
AI summary
The present disclosure relates to a dose indicator comprising, a chassis comprising a chassis frame and a displacement portion comprising a drive part to engage an indexable first display unit indexable about a first display axis, the indexable first display unit comprising a drive tooth to drive an indexable second display unit indexable about a second display axis, the second display axis being non-coaxial with the first display axis, the indexable second display unit comprising two or more second display unit indexing teeth, wherein the drive tooth and each of the second display unit indexing teeth comprise lips on their respective engagement surfaces, the drive tooth lip and second display unit indexing tooth lip each being adapted to engage at an engagement angle that produces a resultant force acting to pull the first display unit and second display unit together. The present disclosure further relates to an actuator for an inhaler, wherein the actuator comprises a dose indicator as described above. The present disclosure is also directed to an inhaler comprising such actuator.