Rotatable Dose Counter for Dry Powder Inhaler
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Solution Overview
Problem
Dry powder inhalers lack a reliable mechanism to accurately count and display the number of doses administered or remaining, leading to potential dose inconsistency and sub-therapeutic administration.
Innovation Solution
A rotatably actuated counter mechanism comprising a first wheel with gear teeth, a second wheel with openings, and a slave wheel with a Geneva mechanism, which incrementally rotates to display the number of doses through a combination of gear engagement and pin alignment, ensuring accurate counting and prevention of inadvertent rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a counter mechanism is added to track doses, then measurement precision of doses remaining is improved, but device complexity increases
Solution Approach 1:
The counter mechanism is divided into separate functional components: a first wheel for units, a second wheel for tens, and a slave wheel with Geneva mechanism for drive transfer. Each component has a specific function, allowing the complex counting task to be segmented into manageable parts that can be manufactured and assembled independently.
Solution Approach 2:
The slave wheel acts as an intermediary between the inhaler's drive mechanism and the display wheels. It receives rotational input from the inhaler and transfers it through the Geneva mechanism to incrementally rotate the first and second wheels, mediating the connection between the actuation mechanism and the counting display.
2Ease of operation
If a rotatory intermittent drive transfer mechanism is used, then ease of operation is improved, but reliability of dose counting deteriorates
Solution Approach 1:
The counter mechanism uses dynamic elements including rotatable wheels, a movable slave wheel, and a Geneva mechanism that converts continuous rotation into intermittent incremental motion. These dynamic components allow the counter to be actuated by the natural rotation of the inhaler while maintaining reliable dose tracking through mechanical engagement.
Solution Approach 2:
The Geneva mechanism on the slave wheel provides periodic action by receiving the foot from the second wheel at specific intervals during rotation. This creates discrete, periodic increments to the counter display, ensuring that each dose actuation is counted reliably rather than continuously, which improves reliability while maintaining ease of operation.
3Manufacturing precision
If multiple wheels with gear teeth are engaged, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The first wheel and second wheel are merged into a single rotational assembly around the first axis, with the slave wheel positioned between them. This combining of multiple counting functions into a compact wheel assembly reduces overall device complexity while maintaining the precision gear engagement needed for accurate dose counting.
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
Provides a reliable, easy-to-read, and accurate count of doses remaining in the inhaler, preventing sub-therapeutic administration by offering a clear warning when the device is running low, thus ensuring correct drug dosage.
Implementation Method 1
A gear is positioned on one face of the slave wheel. The gear is engaged with the gear teeth of the first wheel. The first wheel is rotated about the first axis upon rotation of the slave wheel about the second axis.
Implementation Method 2
A Geneva mechanism is positioned on an opposite face of the slave wheel. The Geneva mechanism has a plurality of receptacles adapted to receive the foot projecting from the second wheel. Engagement of the foot with one of the receptacles incrementally rotates the slave wheel in response to rotation of the second wheel
Implementation Method 3
A plurality of pins are mounted in spaced relation around the Geneva mechanism. The pins project in a direction parallel to the second axis and are engageable with the wall. The pins align with and pass through the openings in the wall when the foot engages one of the receptacles. The pins otherwise engage the wall. Engagement of the pins and the wall prevent rotation of the slave wheel and thereby the first wheel as well, unless the foot is engaged with one of the receptacles and the opening in the wall is aligned with the pins.
Data Source
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AI summary
A rotatably actuated counter (26) is disclosed. The counter includes a ratchet driven unit wheel (30) nested within a tens wheel (34). Each wheel has a radial face (84;60) displaying counting indicia (40;42). The tens wheel is transparent, allowing the indicia on the unit wheel to be viewed adjacent to the indicia on the tens wheel to provide a total count. A slave wheel (32) is positioned between the unit and tens wheels. A gear (70) on one face (72) of the slave wheel engages gear teeth (62) on the tens wheel. A Geneva mechanism (74) on the other face (76) is engaged by a foot (80) on the unit wheel once per rotation. The wheels are rotatably mounted within housing (36) having a sidewall (58) with a window (38) through which the count indicia (15) may be viewed. The unit wheel rotates in ten increments and then rotates the tens wheel through one increment by engaging and rotating the slave wheel.