Autoinjector Door-Driven Spring Loading With Alignment Interlock
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Solution Overview
Problem
Conventional injection devices, both manual and autoinjectors, pose challenges for users lacking dexterity, such as the elderly or children, due to the need for continuous force application and alignment during injections, and electro-mechanical autoinjectors are not as robust as fully mechanical ones.
Innovation Solution
An autoinjector design featuring a case with a hingedly coupled door, a plunger driven by a drive spring, a trigger button, and an interlock sleeve mechanism that ensures proper alignment and activation, allowing for a spring-powered injection process without continuous user force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If manual force is used to drive medicament through needle, then device complexity is reduced, but ease of operation deteriorates due to requiring continuous force application and alignment dexterity
Solution Approach 1:
The injection device automatically performs the injection function after initial activation. The spring mechanism self-activates upon trigger release, and the plunger automatically advances the stopper without requiring continuous user force. The device serves itself by converting stored spring energy into controlled plunger motion, eliminating the need for sustained manual operation.
Solution Approach 2:
The spring is pre-compressed during device assembly or loading, storing mechanical energy before use. The interlock mechanism pre-positions the plunger and prevents premature activation. When the trigger is pulled and released, these preliminary actions are automatically executed, providing the force and control needed for injection without requiring the user to manually compress springs or align components during the injection moment.
2Ease of operation
If spring-powered automatic injection is used, then ease of operation is improved, but device complexity increases due to additional mechanical components
Solution Approach 1:
Multiple functions are merged into the interlock sleeve component. It serves as a protective cover for the needle, an interlock mechanism that prevents premature activation, and a trigger activation interface. The plunger also combines the injection function with the activation trigger mechanism. This functional merging reduces the number of separate components needed, managing device complexity while maintaining automatic operation.
Solution Approach 2:
The trigger button serves multiple functions: it acts as the activation interface for the spring mechanism, engages the interlock mechanism to ensure proper positioning, and initiates the injection sequence. The plunger both advances the stopper for medication delivery and returns to its initial position to reset the interlock for potential reuse. This multi-functionality reduces component count while achieving automatic injection.
3Reliability
If interlock mechanism is implemented to ensure proper alignment, then reliability is improved, but device complexity increases
Solution Approach 1:
The interlock function is merged with the trigger activation mechanism and needle protection cover into the interlock sleeve. This single component ensures proper alignment by physically blocking premature activation while also serving as the interface for trigger engagement. The plunger's dual-function design (injection + reset) further integrates alignment assurance into existing components, managing complexity while improving reliability.
4Reliability
If fully mechanical design is used instead of electro-mechanical, then reliability is improved by eliminating batteries, but functionality is reduced compared to electronic-controlled devices
Solution Approach 1:
The spring mechanism automatically converts stored mechanical energy into controlled plunger motion upon trigger release. The interlock mechanism self-activates based on plunger position, and the needle cover automatically protects the needle. This self-service capability eliminates the need for external power sources or electronic control systems while maintaining reliable, repeatable injection function.
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 design facilitates easy and reliable self-administration of injections by ensuring proper alignment and automatic force application, reducing the risk of incomplete doses and needle stick injuries, and eliminating the need for battery-powered components.
Implementation Method 1
at least one drive spring applying a biasing force on the plunger relative to the case
Data Source
AI summary
An autoinjector includes a case, a door hingedly coupled to the case and having an open position and a closed position, a plunger slidably disposed in the case, and at least one drive spring applying a biasing force on the plunger relative to the case, wherein the door is operably coupled to the plunger, and wherein rotation of the door from the closed position to the open position moves the plunger from a distal position in the case to a proximal position in the case and compresses the at least one drive spring.