Drug Delivery Loading Mechanism for One-Step Spring Reloading
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Solution Overview
Problem
Existing semi-reusable autoinjectors require multiple complex steps and high force for reloading the mechanical drive, posing challenges for users, especially older patients, and often result in unintended medicament dispensing during insertion.
Innovation Solution
A loading mechanism for a drug delivery device with a reusable drive unit and disposable reservoir unit, where the reservoir unit is inserted into the drive unit to simultaneously load the mechanical drive, eliminating the need for additional steps and ensuring the stopper does not move during insertion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the compression spring is manually re-compressed after each injection, then the mechanical drive can be reloaded for the next use, but the user must apply high force and precision which is challenging especially for older patients
Solution Approach 1:
The system performs the reloading function automatically through the docking mechanism. When the disposable cartridge is inserted into the reusable handle, the plunger automatically engages with the drive shaft and the spring is re-compressed without requiring the user to manually apply force. The system uses the insertion motion itself to drive the reloading process.
Solution Approach 2:
The plunger acts as an intermediary element between the disposable cartridge and the reusable handle. During insertion, the plunger is pushed by the cartridge and in turn pushes the drive shaft, which compresses the spring. This intermediary mechanism transfers the insertion motion into the reloading action without requiring direct user manipulation of the spring.
2Ease of operation
If the stopper is manually pushed during insertion, then the mechanical drive can be loaded, but the medicament may be unintentionally dispensed
Solution Approach 1:
The system is divided into two separate functional units: a disposable cartridge containing the medicament reservoir and stopper, and a reusable handle containing the mechanical drive. The cartridge can be inserted without the stopper being pushed, because the reloading function is performed by the plunger engaging with the drive shaft in the handle, not by direct manipulation of the stopper in the cartridge.
Solution Approach 2:
The plunger serves as an intermediary that decouples the insertion motion from direct stopper manipulation. During insertion, the plunger is pushed by the cartridge but transfers this motion to the drive shaft through engagement with the handle, rather than directly pushing the stopper. This prevents unintended medicament dispensing while still achieving the reloading function.
3Reliability
If multiple steps are required for reloading, then the mechanical drive can be properly loaded, but the assembly process becomes complex and time-consuming
Solution Approach 1:
The system combines multiple functions into a single docking action. When the disposable cartridge is inserted into the reusable handle, this single motion simultaneously achieves: (1) attachment of the two units, (2) compression of the spring to load the mechanical drive, and (3) positioning of the plunger in the retracted position. This eliminates the need for separate reloading steps.
Solution Approach 2:
The plunger is pre-configured in the disposable cartridge to engage with the drive shaft in the reusable handle. During insertion, the plunger is already positioned to push the drive shaft and compress the spring, so the reloading action is automatically initiated by the insertion motion itself, without requiring preliminary manual compression or adjustment.
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
The mechanism allows easy and reliable loading of the mechanical drive with a single step, reducing user effort and preventing unintended medicament dispensing, thus simplifying the assembly process and enhancing user convenience.
Implementation Method 1
a compression spring arranged inside the drive unit housing for moving, when loaded, the plunger in the proximal direction
Implementation Method 2
The reservoir unit is insertable into the drive unit from a distal end of the drive unit, wherein the reservoir unit is adapted to contact the plunger with the abutment surface and to push the plunger in a proximal direction to load the compression spring
Data Source
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AI summary
The present invention relates to a loading mechanism for a drug delivery device for dispensing a liquid drug from a reservoir through a needle, the loading mechanism comprising a drive unit and a reservoir unit adapted to hold the reservoir and releasably attachable to the drive unit. The drive unit comprises a drive unit housing defining a longitudinal axis, a plunger movable inside the drive unit housing in a dispensing direction to dispense the liquid drug and a mechanical drive, preferably a compression spring, arranged inside the drive unit housing for moving, when loaded, the plunger in the dispensing direction. The reservoir unit comprises a reservoir unit housing. For loading the drug delivery device, the reservoir unit is insertable into the drive unit housing from a distal end of the drive unit. According to the invention the reservoir unit housing comprises an abutment surface that is adapted to contact the plunger and to push the plunger in a proximal direction to load the mechanical drive, preferably to compress or re-set the compression spring, while the reservoir unit is inserted into the drive unit housing.