Injection Device Torsion Spring Mode Defining Elements
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Solution Overview
Problem
Existing injection devices are difficult for people with poor dexterity or low finger strength to use, as they require manual effort to set and inject doses, increasing the risk of incorrect dosing.
Innovation Solution
An injection device with a torsion spring-powered mechanism that stores energy during dose setting and releases it for automatic injection, featuring mode-defining elements that ensure correct dosing by limiting angular movements to predetermined positions, preventing incorrect dosing and allowing for a priming function.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If manual operation is used to set and inject doses, then the device structure remains simple, but the ease of operation deteriorates for people with poor dexterity or low finger strength
Solution Approach 1:
The injection device is designed to perform the injection action automatically using energy stored in a spring member during the dose setting phase. The system serves itself by converting the setting action into stored energy that automatically drives the injection mechanism, eliminating the need for separate manual injection effort from the user.
Solution Approach 2:
The dose setting mechanism performs preliminary action by storing energy in the spring member during the setting phase. This stored energy is then released to automatically drive the injection mechanism, so the difficult injection action is prepared in advance during the easier setting phase.
2Reliability
If manual injection is required, then the device complexity is reduced, but the reliability of complete dose injection deteriorates
Solution Approach 1:
The device incorporates mode defining elements that provide feedback through their angular and axial positions. These elements indicate whether the device is in dose setting mode or injection mode, and the shaped configuration ensures that mode transitions only occur at correct dose settings, providing feedback that confirms proper operation.
Solution Approach 2:
The spring member acts as an intermediary that couples the dose setting mechanism with the injection mechanism. It transfers and stores energy from the setting action, then releases it to drive injection, mediating between user input and the injection output while ensuring complete dose delivery.
3Ease of operation
If the dose setting mechanism allows free rotation, then the ease of operation is improved, but the manufacturing precision of dose setting deteriorates
Solution Approach 1:
The mode defining elements dynamically change their degrees of freedom based on the operational phase. During dose setting, the elements allow rotational movement for ease of operation. During injection, the same elements constrain rotation and enable only axial movement, providing dynamic control over movement freedom based on the current operational mode.
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 device is easier to use for individuals with limited dexterity, minimizing the risk of incorrect dosing and ensuring consistent delivery of predetermined doses, making it suitable for repetitive self-injections like insulin administration.
Implementation Method 1
a torsion spring being connected to the dose setting mechanism in such a manner that operation of the dose setting mechanism causes energy to be stored in the torsion spring and the torsion spring being connected to the injection mechanism in such a manner that operation of the injection mechanism causes energy which has previously been stored in the torsion spring to be released
Data Source
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AI summary
An injection device (1) for injecting predetermined doses of liquid drug is disclosed. The injection device (1) comprises a dose setting mechanism and an injection mechanism. A torsion spring (12) is connected to the dose setting mechanism and to the injection mechanism in such a manner that energy is stored in the torsion spring (12) during dose setting, and the energy is released during injection, the stored energy being used for causing the set dose to be injected. A first mode defining element (8) and a second mode defining element (9) are angularly movable relative to each other in response to operation of the dose setting mechanism. They are also axially movable relative to each other between a first position in which the dose setting mechanism can be operated to set a dose and a second position in which the injection mechanism can be operated to inject a set dose. The mode defining elements (8, 9) are shaped in such a manner that mutual axial movements between the first position and the second position are only possible at a limited number of mutual angular positions, said angular positions each corresponding to setting of a predetermined dose of liquid drug. Thereby the risk of setting and/or injecting an incorrect dose is considerably reduced. Furthermore, the torsion spring (12) ensures easy operability for persons having poor dexterity or low finger strength.