Inhaler Non-Circular Gears Actuation Force Profile
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Solution Overview
Problem
Existing dry powder inhalers with blister strips require high initial force due to mechanisms like cantilevers and ramps, which can be disadvantageous, especially when multiple blisters are indexed and pierced or when blisters need to be squashed, increasing user effort and potentially making the device harder to use for elderly or young patients.
Innovation Solution
The use of non-circular gears with varying gear ratios between the actuator gear and drive gear, allowing the force profile to be designed to reduce initial force requirements and match the needed force for indexing and piercing, eliminating the need for ramps and cantilevers, and ensuring consistent blister alignment and piercing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a cantilever and ramp mechanism is used to control force during actuator rotation, then the force profile can be controlled throughout the stroke, but the initial force required is increased above what is inherently needed for indexing
Solution Approach 1:
The patent applies dynamics by using non-circular gears with varying radii that change during rotation. The actuator gear has a varying radius profile that dynamically adjusts the gear ratio throughout the actuation stroke, allowing the force required to be matched to the actual indexing needs without adding excessive initial force through static mechanical advantage mechanisms like cantilevers and ramps
Solution Approach 2:
The patent changes the geometric parameters of the gears from circular to non-circular shapes, specifically varying the radius of the actuator gear throughout rotation. This parameter change allows the gear ratio to vary dynamically, optimizing the force transmission to match the indexing requirements without the need for additional force-amplifying mechanisms
2Productivity
If multiple blisters are indexed and pierced on each actuation, then productivity increases, but the force required to operate the actuator increases
Solution Approach 1:
The non-circular gear mechanism dynamically adjusts the gear ratio during actuation to match the varying force requirements of indexing multiple blisters. The varying radius profile allows the system to provide higher mechanical advantage when needed for piercing while maintaining ease of operation during indexing phases, enabling multiple blisters to be processed per actuation without proportionally increasing the force requirement
3Volume of moving object
If used blisters are squashed to save space, then device compactness improves, but the force required to operate the actuator increases
Solution Approach 1:
The varying radius profile of the non-circular actuator gear dynamically provides mechanical advantage during the blister squashing phase. By adjusting the gear ratio at appropriate points in the actuation cycle, the system can apply the necessary force to compress used blisters into the housing while maintaining reasonable overall actuator force requirements
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
This solution reduces the initial force required for actuation, making the inhaler easier to use by matching the force profile to the necessary force for blister indexing and piercing, while maintaining effective operation and space efficiency by squashing used blisters, thus improving user experience and device usability.
Implementation Method 1
an actuator gear mounted for rotation about a first axis which is driven by the actuator, and which comprises an actuator gear element, a drive gear for driving the indexing wheel, mounted for rotation about a second axis, which engages with the actuator gear element, characterized in that the gear ratio between the actuator gear element and the drive gear varies as they rotate during operation of the actuator
Data Source
AI summary
An inhaler is provided, comprising a housing which contains a blister strip having a plurality of blisters which contain powdered medicament for inhalation; a mouthpiece mounted on the housing through which the medicament is inhaled by a user; an actuator; a blister piercing member; an indexing wheel for sequentially moving each blister into alignment with the blister piercing member when the user operates the actuator; an actuator gear, mounted for rotation about a first axis, which is driven by the actuator and which comprises an actuator gear element; and a drive gear for driving the indexing wheel, mounted for rotation about a second axis, which engages with the actuator gear element. The inhaler is characterized in that the gear ratio between the actuator gear element and the drive gear varies as they rotate during operation of the actuator.