Inhaler Dose Counter Worm Drive for Accurate Low-Complexity 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 a worm and gear system that converts rotational motion from the inhaler's priming operation into a count of dispensed doses, reducing the number of components and simplifying manufacture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional dose counters use multiple small mechanical parts to index the display, then the dose counting function is achieved, but the device complexity increases and manufacturing cost rises
Solution Approach 1:
The patent combines multiple separate mechanical components (display indexing mechanism, dose counting mechanism, and actuation mechanism) into an integrated system where a single actuation motion simultaneously advances the dose counter and indexes the display. The counter ring with circumferential drive features merges the display indexing function with the dose counting function, eliminating the need for separate indexing mechanisms.
Solution Approach 2:
The counter ring serves multiple functions: it displays the remaining doses, indexes the display numerals, and engages with the worm gear to transfer motion. The circumferential drive features on the counter ring provide both the indexing mechanism and the gear engagement interface, making the component universal and reducing overall system complexity.
2Reliability
If traditional dose counters use several small mechanical parts, then dose counting is achieved, but assembly difficulty increases
Solution Approach 1:
By merging the display indexing function and dose counting function into a single integrated mechanism, the patent reduces the number of separate components that need to be assembled. The counter ring with built-in circumferential drive features eliminates the need for separate indexing gears and display advancement mechanisms, simplifying assembly procedures.
3Measurement precision
If traditional dose counters require tight dimensional manufacturing tolerances, then measurement precision is improved, but manufacturing cost increases
Solution Approach 1:
The patent segments the continuous rotational motion into discrete dosing units through the circumferential drive features on the counter ring. Each drive feature corresponds to a specific dose increment, allowing the system to achieve precise dose counting through geometric segmentation rather than relying on tight dimensional tolerances throughout the entire mechanism.
Solution Approach 2:
The patent changes the approach to achieving precision from dimensional tolerance control to geometric parameter control. The circumferential drive features are defined by their angular spacing and radial position rather than precise dimensional fits, allowing for more relaxed manufacturing tolerances while maintaining accurate dose counting through the inherent geometry of the worm-gear engagement.
4Ease of manufacture
If the dose counter uses a simplified mechanism with fewer components, then manufacturing cost decreases, but reliability may worsen
Solution Approach 1:
The circumferential drive features on the counter ring provide self-indexing and self-locking functionality. Each drive feature automatically engages with the worm gear recesses to advance the counter by a precise increment, eliminating the need for separate indexing mechanisms or adjustment mechanisms. This self-service capability maintains reliability while reducing component count.
Solution Approach 2:
The worm gear engagement with the circumferential drive features provides inherent motion control and positioning before each dose increment. The helical engagement of the worm gear ensures smooth, controlled advancement and prevents overshooting or missed counts, providing built-in error prevention that maintains reliability without requiring additional components.
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 solution allows for a reliable and economic dose counting mechanism that can be applied to various types of inhalers, with reduced complexity and improved assembly, while providing accurate dose indication.
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
Figure 1A
Figure 1B~1C
Figure 1D
AI summary
In general terms the present invention proposes a dose counter for registering a count of doses dispensed from an inhaler. The dose counter comprises a counter ring comprising a circumferential drive feature. The dose counter also comprises 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 comprises recesses uniformly distributed along the helical path. The dose counter further comprises a cylindrical body comprising 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.