Dual-Tooth Ratchet Mechanism for Incremental Inhaler Loading
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Solution Overview
Problem
Conventional drug inhalers require high torque for loading, which can be challenging for patients with limited strength or dexterity, and may result in premature activation and partial dose release, leading to incorrect dose counting.
Innovation Solution
A ratchet mechanism with a ratchet ring and chassis teeth configuration that allows incremental loading by pausing the twist action, reducing the required force and preventing premature activation, featuring a ratchet ring with alternating sets of teeth on the ratchet ring and chassis to control rotation and maintain the loaded state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high torque is applied to load the inhaler, then the inhaler attains a fully loaded state, but patients with limited strength or dexterity cannot complete the loading action
Solution Approach 1:
The ratchet mechanism segments the continuous rotation required for loading into discrete incremental steps. Each tooth engagement represents a discrete step, allowing the loading action to be divided into manageable increments that patients can complete with limited strength.
Solution Approach 2:
The ratchet mechanism enables periodic action by allowing the user to pause between tooth engagements during the loading process. The user can apply torque incrementally, releasing and reapplying force in periodic cycles until full loading is achieved, making the operation feasible for patients with limited strength.
2Ease of operation
If the inhaler is released before attaining the fully loaded state, then the patient can pause the twist action, but the inhaler activates in a premature state and releases a partial dose
Solution Approach 1:
The ratchet mechanism applies preliminary anti-action by preventing reverse rotation before full loading is achieved. The teeth engage to block any backward movement that would trigger premature activation, ensuring that the inhaler can only be activated after complete loading has occurred.
Solution Approach 2:
The ratchet mechanism provides mechanical feedback through tooth engagement that confirms the loading state. The counter mechanism receives feedback from the ratchet's position, ensuring accurate dose counting only after full loading is achieved, preventing premature activation.
3Ease of operation
If the inhaler is released before full loading, then the patient can pause, but a partial dose is released which is wasted and not registered by the counter
Solution Approach 1:
The ratchet mechanism prevents premature activation by blocking reverse rotation before full loading. This preliminary anti-action ensures that no partial dose is released during the loading process, eliminating drug waste while still allowing patients to pause between incremental loading steps.
4Reliability
If the ratchet mechanism uses more teeth engagements, then the loading torque is better controlled, but the device complexity increases
Solution Approach 1:
The ratchet teeth are designed with asymmetric profiles having different leading and trailing edge angles. This asymmetry provides controlled torque characteristics where the leading edge allows incremental rotation while the trailing edge prevents reverse movement, achieving reliable torque control without requiring an excessive number of teeth.
Data Source
AI summary
Disclosed is a ratchet mechanism having ratchet ring and a chassis. The ratchet ring is rotatable about an axis relative to the chassis, with a general direction of rotation determined by teeth of the ratchet mechanism. The ratchet ring has a first set of teeth arranged regularly around the ratchet ring and protruding in a first axial direction from the ratchet ring and a second set of teeth arranged regularly around the ratchet ring and protruding in a second opposite axial direction from the ratchet ring. The chassis has a third set of teeth arranged regularly and protruding in the second axial direction and generally opposed to the first set of teeth, and a fourth set of teeth arranged regularly and protruding in the first axial direction and generally opposed to the second set of teeth.