Inhaler Step-Action Indexing Mechanism for Dosage Tracking
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Solution Overview
Problem
Conventional hand-held devices for medicinal aerosol therapy face challenges in providing a user-friendly and space-efficient mechanism to track the remaining medicament dosage, as the limited space restricts the design of the scale ring and its markings, making it difficult to accurately indicate the dosage dispensed.
Innovation Solution
A step-action indexing mechanism with a rotary ring concentric to the valve tube, utilizing a planet-gear drive and a toothed rim, allows for stepwise rotation of the scale ring, enabling clear indication of the medicament dosage through a graduated scale visible through a viewing window, while ensuring the mechanism is securely integrated into the device's housing and protected during use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a scale ring is provided that turns about an axis coinciding with the cartridge axis, then the dosage indication is improved, but the space available for scale markings is limited due to the small lateral surface area
Solution Approach 1:
The patent transitions from a two-dimensional scale ring to a three-dimensional stepped drum structure. The dosage markings are distributed across multiple stepped surfaces (first, second, and third stepped surfaces) at different radial distances from the axis, effectively utilizing the third dimension (radial depth) to accommodate comprehensive dosage indication while maintaining a compact lateral footprint.
2Ease of repair
If the scale ring is made accessible for cleaning, then ease of maintenance is improved, but the mechanism becomes more complex requiring additional design considerations
Solution Approach 1:
The mechanism is segmented into a removable scale drum component that can be separated from the housing. The scale drum is held in place by a retaining ring that can be released to allow removal of the scale drum for cleaning, while the indexing mechanism remains in the housing. This segmentation enables easy cleaning of the scale markings without disassembling the entire device.
3Measurement precision
If a step-action indexing mechanism is used, then dosage tracking accuracy is improved, but the mechanism requires more space and becomes more complex
Solution Approach 1:
The indexing mechanism is nested within the scale drum structure. The indexing finger engages with stepped surfaces that are integrated into the scale drum itself, and the retaining ring provides both retention and indexing functions. This nested arrangement minimizes the space required for the indexing mechanism while maintaining accurate step-action dosage tracking.
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 provides a space-saving, user-friendly, and accurate method to track the medicament dosage, preventing inadvertent actuation and facilitating easy cleaning, with the mechanism returning to its original position automatically, ensuring correct functioning and easy assembly.
Implementation Method 1
a planet-gear drive by a rotary toothed rim which is likewise concentric with the valve tube
Implementation Method 2
an indexing finger which can yield elastically in the indexing direction
Data Source
AI summary
A hand-held device for apportioned delivery of sprayable substances, in particular inhaler medicaments, having a cartridge which is displaceable by pressing in a housing into the open position for delivery, and an indexing mechanism which is moved along by the cartridge during the opening stroke of the cartridge for registering and displaying delivery actuations which have been carried out, which indexing mechanism is disposed in a housing centrally below the opening-side end wall of the cartridge, overlappingly with respect to the valve tube of the cartridge. In order to configure a hand-held device of the type in question in a spatially advantageous manner with a simplified construction and such that it is more reliable in terms of handling, it is proposed to displace plate-shaped housing as a whole with the cartridge, except for a step-by-step indexing finger star disposed therein.