Injection Device Ratchet Indexing for Precise Dose Selection
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Solution Overview
Problem
Existing drug delivery devices face challenges in accurately dispensing variable doses, particularly as patient needs have evolved with increasing medicament concentrations and larger dose sizes, leading to difficulties in dialing and dispensing low doses with precision, and a need for improved tactile and audible feedback.
Innovation Solution
An injection device with a housing featuring a thread and ratchet mechanism that provides tactile indexing through distinct ratchet features along a helical path, allowing discrete dose settings with adjustable torque feedback during dialing and dispensing, and a drive member that disengages partially during dose dispensing to maintain indexing accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If medicament concentration is increased to reduce device size, then device compactness is improved, but dose dialing precision for low doses deteriorates
Solution Approach 1:
The dose indicator's travel path is segmented into multiple discrete positions along the helical groove, with each position corresponding to a specific dose value. This segmentation allows precise dose selection even when the overall device size is reduced through higher medicament concentration.
Solution Approach 2:
The ratchet mechanism provides tactile feedback at each discrete dose position, allowing users to accurately identify and select the desired dose. This feedback mechanism maintains dose dialing precision despite the increased medicament concentration and reduced device volume.
2Ease of operation
If ratchet mechanism is added to provide tactile feedback, then ease of operation is improved, but device complexity increases
Solution Approach 1:
The ratchet mechanism is integrated with the helical groove structure of the dose indicator, combining the dosing mechanism and feedback mechanism into a single unified structure. This merging provides tactile feedback for ease of operation while minimizing the increase in overall device complexity.
Solution Approach 2:
The helical groove structure serves multiple functions: it guides the dose indicator's movement, defines discrete dose positions, and works with the ratchet mechanism to provide tactile feedback. This multi-functionality achieves ease of operation without proportionally increasing device complexity.
3Measurement precision
If engaging members are provided at multiple positions, then measurement precision is improved, but manufacturing complexity increases
Solution Approach 1:
The engaging members are uniformly distributed at multiple positions along the helical groove with consistent structural characteristics. This homogeneous design allows for standardized manufacturing processes, reducing the impact of manufacturing complexity while maintaining high dose position accuracy.
Solution Approach 2:
The number and spacing of engaging members are optimized as design parameters to achieve the required measurement precision. By carefully selecting these parameters, the patent balances dose position accuracy with manufacturing feasibility, avoiding excessive complexity.
Data Source
AI summary
An injection device including a housing, a dose indicator, and a release mechanism. The dose indicator is positioned within the internal space of the housing and includes a number of engaging members at least one thereof being configured to contact multiple of distinct ratchet features in course of a helical or screwing movement in distinct positions to provide a user with a tactile indexing appearance in the way of an increased or decreased dwelling torque at each of the multiple distinct positions. The release mechanism is connected to the dose indicator and includes a drive member. The release mechanism is configured to, when activated during dose dispense, urge the engaging members away from the distant position and against the force of the resilient bias thereby suspending the indexing ratchet appearance at least for a subset of the multiple distinct positions.