Inhaler Dose Counter with Helical Worm Drive Indexing
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Solution Overview
Problem
Existing dose counters for inhalers are complex, costly, and require tight manufacturing tolerances, leading to assembly difficulties and increased costs.
Innovation Solution
A dose counter mechanism utilizing a counter ring with circumferential drive features, a worm with a helical gear, and a cylindrical body that converts linear or reciprocating motion into rotary motion, reducing the number of components and simplifying manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional dose counters use several small mechanical parts, then the dose counting function is achieved, but the device complexity increases and manufacturing cost increases
Solution Approach 1:
The patent combines multiple separate mechanical components (counter ring, drive features, indexing mechanism) into an integrated cylindrical body with helical engagement features. The cylindrical body itself serves as both the housing and the driving mechanism, eliminating the need for separate gears and linkages. This merging reduces part count while maintaining reliable dose counting functionality.
Solution Approach 2:
The cylindrical body performs multiple functions simultaneously: it serves as the structural housing, the driving mechanism through its helical engagement feature, the counter ring, and the indexing mechanism. This multi-functionality eliminates the need for separate dedicated components for each function, reducing overall device complexity.
2Reliability
If traditional dose counters use several small mechanical parts, then the dose counting function is achieved, but assembly difficulty increases
Solution Approach 1:
By integrating the housing, drive mechanism, and counter ring into a single cylindrical body, the patent eliminates multiple assembly steps. The helical engagement feature is formed as an integral part of the cylindrical body, requiring no separate assembly of gears or linkages, thereby significantly reducing assembly difficulty.
3Measurement precision
If traditional dose counters require tight dimensional manufacturing tolerances, then the dose counting accuracy is maintained, but manufacturing cost increases
Solution Approach 1:
The helical engagement feature is designed with discrete engagement points along its length, allowing the cylindrical body to index through distinct positions. This segmentation provides inherent mechanical positioning that maintains counting accuracy without requiring tight tolerances on the overall cylindrical body dimensions.
Solution Approach 2:
The helical engagement feature acts as an intermediary mechanism that translates linear motion into rotational indexing. This intermediate mechanism provides mechanical advantage and self-positioning, reducing the need for tight tolerances on the primary moving parts while maintaining accurate dose counting.
4Ease of manufacture
If the dose counter uses a simplified design with fewer components, then manufacturing cost decreases, but reliability may worsen
Solution Approach 1:
The integration of multiple functions into the cylindrical body reduces the number of potential failure points associated with separate components and their interfaces. Fewer mechanical joints and connections mean fewer opportunities for wear, misalignment, or failure, thereby maintaining or even improving reliability despite the simplified design.
Solution Approach 2:
Instead of using a complex mechanism to achieve reliable counting, the patent inverts the approach by using a simple cylindrical body with helical features that inherently provides reliable indexing through its geometric design. The reliability emerges from the geometry itself rather than from complex control mechanisms.
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 simplified design allows for reliable dose counting with fewer components, reducing costs and assembly complexity while being applicable to various types of inhalers.
Implementation Method 1
a worm comprising a shaft and a gear extending in a helical path about the axis of the shaft for driving the counter ring
Implementation Method 2
The gear comprises one or more recesses distributed along the helical path of the gear
Data Source
AI summary
In general terms the aspects of the disclosed embodiments proposes a dose counter for registering a count of doses dispensed from an inhaler. The dose counter includes a counter ring including a circumferential drive feature. The dose counter also includes a worm comprising a shaft and a gear extending in a helical path about the axis of the shaft for driving the counter ring. The gear includes recesses uniformly distributed along the helical path. The dose counter further includes a cylindrical body including an engagement feature for driving the gear, the engagement feature extending in a helical or spiral path from the cylindrical body to engage the gear such that relative rotational movement between the cylindrical body and the worm rotates the worm about its shaft.