Torsion Spring Injection Mechanism for Full Single-Stroke Dosing
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Solution Overview
Problem
Existing torsion spring driven injection devices allow users to set and expel doses that are not the full predetermined size, and may require multiple strokes for dose delivery, which can lead to errors in dosing.
Innovation Solution
A torsion spring driven injection device with a blocking structure that prevents dose ejection until a minimum dose size is set, and a mechanism that ensures the full dose is expelled in one stroke by coupling a rotatable display element to a release element, allowing axial movement only when the predetermined dose is reached.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the rotatable dose setting element is allowed to rotate freely to set any dose size, then the ease of operation is improved, but the dosing accuracy deteriorates because users may set incorrect dose sizes
Solution Approach 1:
The blocking structure is pre-configured to automatically engage or disengage based on the rotation angle of the dose setting element. Before the user completes the required rotation to set the full predetermined dose, the blocking structure prevents activation. This preliminary mechanical constraint ensures that only the correct dose size can be set, eliminating dosing errors while maintaining ease of operation through automatic control.
2Ease of operation
If the device allows multiple strokes for dose delivery, then the ease of operation is improved for flexible dosing, but the dosing accuracy deteriorates due to potential pauses and errors
Solution Approach 1:
The blocking structure is designed to remain engaged throughout the entire dose delivery process until the full predetermined dose is expelled. This preliminary mechanical constraint prevents the user from pausing or stopping the injection mid-dose, ensuring that the complete dose is delivered in one continuous action. The structure automatically disengages only after the full dose has been delivered, providing both accuracy and simplicity.
3Measurement precision
If the blocking structure prevents dose ejection until minimum dose size is set, then the dosing accuracy is improved, but the device complexity increases
Solution Approach 1:
The blocking structure is designed as a self-regulating mechanical component that automatically engages and disengages based on the rotation angle of the dose setting element. The structure uses the user's own rotation action to trigger the blocking mechanism - when the user rotates the dial to set the full predetermined dose, the blocking structure automatically disengages to allow dose delivery. This self-service design achieves dosing accuracy without requiring additional control systems or complex mechanisms.
Solution Approach 2:
The blocking structure acts as a mechanical intermediary between the dose setting element and the dose delivery mechanism. It translates the rotation angle of the dose setting element into a binary state - blocked or unblocked - based on whether the full predetermined dose has been set. This intermediary component provides a simple yet effective way to enforce dosing accuracy without complex electronic or mechanical control systems.
4Ease of operation
If the release element can move axially freely, then the ease of operation is improved for rapid dose delivery, but the dosing accuracy deteriorates because the full predetermined dose cannot be ensured
Solution Approach 1:
The blocking structure is pre-positioned to constrain the release element's axial movement until the dose setting element is rotated to the correct angle corresponding to the full predetermined dose. Only when the blocking structure automatically disengages does the release element become free to move axially for rapid dose delivery. This preliminary mechanical constraint ensures that rapid delivery only occurs after the correct dose has been set, combining speed with accuracy.
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
Ensures that the set dose is ejected only when the full predetermined size is reached, preventing errors and requiring a single stroke for dose delivery, enhancing dosing accuracy and user convenience.
Implementation Method 1
a rotatable dose setting structure which transfer rotation from the dose setting element to a straining of a torsion spring such that a torque is stored in the torsion spring upon rotation of the dose setting element
Data Source
Figure 1
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AI summary
The invention relates to a torsion spring driven injection device for ejecting set doses of a liquid drug. In a first aspect the torsion spring driven injection device is provided with a blocking structure which is operated by the rotatable display element such that the set dose can only be expelled when a certain minimum dose size has been set. In a second aspect the torsion spring driven injection device is provided with a release mechanism which secures that the set dose can only be expelled as one single full dose in one stroke. The two aspects can easily be combined such that the predetermined minimum dose size most be expelled as one single dose.