Torsion Spring Injector Driver Release for Cartridge Reuse
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Solution Overview
Problem
Existing torsion spring driven injection devices are designed as pre-filled units, making them disposable after the drug is depleted, lacking a simple and reliable mechanism for releasing the piston rod to allow cartridge replacement.
Innovation Solution
A torsion spring driven injection device with a two-part piston rod driver mechanism, featuring a rotatable outer element and an axially movable inner element, facilitated by a movable sleeve or sleeve-like element, allowing the piston rod to be released and retracted for cartridge exchange.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the injection device is designed as a pre-filled disposable unit, then the device is simple and reliable for single use, but it cannot be reused after the drug is depleted
Solution Approach 1:
The piston rod driver is divided into two separate elements: an outer element that remains stationary and an inner element that moves axially. This segmentation allows the inner element to be released from the outer element, enabling the piston rod to be rotated back and the cartridge to be replaced, thus achieving reusability without significantly increasing overall device complexity
Solution Approach 2:
The piston rod driver transitions from a static connected structure to a dynamic releasable structure. The inner element can move axially relative to the outer element and be positioned in either a first position (uncoupled) or a second position (coupled), allowing the device to switch between locked and released states for cartridge replacement
2Adaptability or versatility
If a release mechanism is added to allow piston rod release for cartridge replacement, then the device becomes reusable, but the mechanism complexity increases
Solution Approach 1:
A compression spring is used to automatically urge the inner element toward the first position (uncoupled position) when the cartridge holder is removed. This self-service mechanism eliminates the need for manual intervention to release the piston rod driver, simplifying the release process while maintaining reusability
Solution Approach 2:
The release mechanism is integrated into the existing cartridge holder structure. The movable element is operably connected to the cartridge holder, so that removal of the cartridge holder automatically triggers the release of the inner element from the outer element, combining the cartridge replacement function with the release mechanism
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
Enables the device to be reused multiple times by allowing easy replacement of cartridges, reducing waste and lowering the overall cost of medication delivery.
Implementation Method 1
A strained torsion spring holding a torque for rotating the rotatable piston rod driver during dose expelling
Implementation Method 2
An internal thread associated with the housing structure and engaging the outer thread on the piston rod such that the piston rod is moved helically when rotated
Data Source
AI summary
The invention relates to an injection device wherein the drive element transferring rotation to the piston rod is divided into two elements which are able to move axially in relation to each other such that the drive mechanism can be released to allow the user to reset the piston rod and change the cartridge.