Medicament Delivery Device Telescopic Dose Drum Mechanism
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Solution Overview
Problem
Existing medicament delivery devices face issues with precise dose setting, potential for setting larger doses than available, and mechanical complexities leading to user confusion and noise due to component play and friction.
Innovation Solution
A medicament delivery device featuring a telescopic dose drum and a resilient spinning element with a stop body that prevents setting doses larger than the remaining quantity, using a ring-shaped stop member and a radially supported piston plunger to minimize play and friction, and a dose setting knob for easy access.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a clutch or uni-directional connection mechanism is used to provide dose setting and delivery functions, then the device can deliver different dose quantities, but the device complexity increases with multiple interacting components and threaded engagement mechanisms
Solution Approach 1:
The patent combines the dose setting drum and drive sleeve into a single integrated component that performs both dose setting and delivery functions. The drive sleeve is configured to rotate relative to the housing to set the dose and also to drive the plunger rod for medicament delivery, eliminating the need for separate clutch mechanisms or uni-directional connection components.
Solution Approach 2:
The drive sleeve serves multiple functions: it acts as the dose setting mechanism when rotated relative to the housing, serves as the connection element to the plunger rod, and functions as the delivery mechanism when it moves axially to push the plunger rod. This multi-functional design reduces the overall number of components while maintaining full dose setting and delivery capability.
2Force
If threaded engagement mechanisms are used for connection, then the device can provide controlled force transmission, but the manual force required by the user becomes too large
Solution Approach 1:
The connection between the drive sleeve and plunger rod uses a dynamic snap-fit mechanism with engagement protrusions and recesses rather than static threaded engagement. This allows the connection to engage and disengage easily with minimal manual force while still providing controlled force transmission during the delivery phase when the drive sleeve moves axially.
Solution Approach 2:
The force transmission is segmented into two distinct phases: dose setting phase where the drive sleeve rotates relative to the housing without engaging the plunger rod, and delivery phase where the drive sleeve engages the plunger rod via snap-fit protrusions for axial movement. This segmentation allows easy operation during setting while providing controlled force during delivery.
3Ease of operation
If play and gaps are introduced between elongated components to prevent jamming, then the components can move freely, but the risk of lack of support increases leading to rattling and noise
Solution Approach 1:
The patent employs resilient elements and flexible sealing structures between components that provide continuous contact and support while allowing necessary movement. These flexible elements eliminate gaps and prevent rattling noise while maintaining the freedom of movement needed to prevent jamming during dose setting and delivery operations.
Solution Approach 2:
Resilient elements are positioned between the drive sleeve and housing, and between other moving components, to provide continuous cushioning contact. This beforehand cushioning ensures that components remain supported throughout their movement range, preventing rattling and noise while allowing the play necessary to prevent jamming.
4Reliability
If direct action between threads is used to prevent setting larger doses than available, then the nut stops rotating when reaching the end of the helical thread, but the components can be turned quite a turning distance before friction becomes too high, leading to imprecise stopping
Solution Approach 1:
The patent replaces the threaded engagement mechanism with a direct rotational stop mechanism. A stop element on the drive sleeve interacts with a corresponding stop feature on the housing to provide a distinct, precise stopping point when the maximum dose is set. This eliminates the gradual friction-based stopping of threaded mechanisms and provides clear tactile and visual feedback for precise dose setting.
Solution Approach 2:
The stop mechanism provides clear tactile feedback when the maximum dose is reached, and the device includes visual indicators that show the user the current dose setting and when the maximum has been reached. This feedback mechanism ensures users can precisely set doses without accidentally selecting more than the available medicament quantity.
Data Source
AI summary
A medicament delivery device includes a housing having proximal and distal ends; a hollow piston plunger within the housing; a telescopic dose drum concentric between the housing and the plunger; and a plunger driver to drive the plunger toward the proximal end having a hollow drive drum sleeve movable within and coupleable to the piston plunger and fixed to the dose drum; an actuator operably connected to the drive drum sleeve; and a stop body for inhibiting rotation of the dose drum and drive drum sleeve when a set dose equals a remaining dose in a medicament container. The drive drum sleeve and piston plunger are operatively coupled such that axial movement of the actuator toward the proximal end forces the drive drum sleeve and piston plunger to couple, whereby the piston plunger and dose drum are displaced toward the proximal end for delivering the set dose.