Drug Delivery Cartridge Flange Alignment Against Arm Deflection
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Solution Overview
Problem
Existing drug delivery devices face issues with arm member deflection and rotation, leading to potential blockages and unsafe user interactions due to inadequate support mechanisms, which compromise the safety and functionality of the device.
Innovation Solution
The drug delivery device incorporates protruding supporting features on the arm member and body to limit radial movement, ensuring proper alignment and preventing deflection, while also using a non-rotation symmetric flange design to maintain stability and facilitate easy assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the arm member is made thin to allow short cooling times during molding, then productivity is improved, but the arm member becomes prone to deflection and outward bending under axial pressure
Solution Approach 1:
The arm member is segmented into a thin-walled portion for rapid cooling and a reinforced portion with protruding supporting features that prevent deflection. This allows the arm member to be made thin for productivity while maintaining strength where needed.
Solution Approach 2:
The arm member has different structural qualities at different locations: thin walls in regions requiring rapid cooling and reinforced structures with protruding supporting features in regions requiring deflection prevention. This local differentiation resolves the contradiction between productivity and strength.
2Ease of operation
If a gap is left between the body and arm member to allow axial movement, then ease of operation is improved, but the arm member becomes vulnerable to rotation and blocking
Solution Approach 1:
The flange is designed with non-rotation symmetric features that interact with corresponding features on the arm member and body. This asymmetric interaction allows axial movement while preventing rotation, resolving the contradiction between ease of operation and reliability.
Solution Approach 2:
The protruding supporting features act as intermediaries between the arm member, flange, and body. These features provide mechanical interference that prevents rotation while allowing axial movement, bridging the gap between operational flexibility and rotational stability.
3Reliability
If the flange has a non-rotation symmetric design, then rotation prevention is improved, but manufacturing complexity increases
Solution Approach 1:
The flange incorporates non-rotation symmetric features such as protrusions or keyways that are relatively simple to mold. These asymmetric features prevent rotation through mechanical interference with corresponding features on the arm member and body, achieving reliability without excessive manufacturing complexity.
4Strength
If the arm member is supported radially outward, then deflection prevention is improved, but device complexity increases
Solution Approach 1:
The support function is segmented into discrete protruding supporting features rather than a continuous complex structure. These individual features provide radial support to prevent deflection while keeping the overall design simple and manufacturable.
Data Source
AI summary
The disclosure relates to a drug delivery device comprising a body extending along a longitudinal axis, at least one arm member arranged within the body and extending essentially parallel to the longitudinal axis, and a container retaining a drug, wherein the container comprises a flange that is arranged at an axial position along the longitudinal axis, wherein the flange has at least one first radial edge region having a first radial distance to the longitudinal axis and at least one second radial edge region having a second radial distance to the longitudinal axis, wherein the second radial distance is greater than the first radial distance, and wherein, in the axial position, the at least one arm member is arranged and configured such that at least one aligning feature of the arm member is arranged at a third radial distance to the longitudinal axis that is smaller than the second radial distance.