Spring-Loaded Autoinjector Door Mechanism for Full-Dose Delivery
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Solution Overview
Problem
Conventional autoinjectors face challenges such as the need for manual dexterity, potential premature injection stoppage, high force requirements, and complexity in electro-mechanical or fully electronic devices, which can be difficult to repair.
Innovation Solution
An autoinjector design featuring a hingedly coupled door, a plunger with a drive spring, a trigger button, an interlock sleeve, and a ratchet mechanism, allowing for easy operation and reliable injection delivery without the need for continuous manual 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 required dexterity and continuous pressure
Solution Approach 1:
The patent replaces the manual mechanical system with an automated mechanical system using a spring-driven plunger mechanism. The spring automatically provides the force needed to push medicament through the needle, eliminating the need for manual dexterity and continuous pressure application while maintaining mechanical simplicity without electronic components.
Solution Approach 2:
The spring is pre-loaded in a compressed state before use, storing potential energy that is automatically converted to kinetic energy during injection. This preliminary action eliminates the need for continuous manual force application, as the pre-compressed spring automatically provides the necessary driving force throughout the injection process.
2Reliability
If button/plunger is continuously pressed during injection, then injection delivery is maintained, but ease of operation deteriorates due to force requirements and dexterity needs
Solution Approach 1:
The spring-driven plunger mechanism is self-actuating once triggered. The stored energy in the compressed spring automatically drives the plunger forward to deliver the full medicament dose without requiring continuous user intervention or force application. The mechanism serves itself by converting stored potential energy into the kinetic energy needed for complete injection delivery.
Solution Approach 2:
The injection mechanism operates through a single triggering action that initiates a periodic sequence: the spring compresses, releases, and drives the plunger through the complete injection cycle. This transforms continuous manual pressing into a single periodic trigger action, maintaining reliable medicament delivery while dramatically improving ease of operation.
3Ease of operation
If button/plunger is released prematurely, then ease of operation improves, but reliability deteriorates due to injection stoppage and incomplete dose delivery
Solution Approach 1:
The spring is pre-compressed and locked in a ready state before triggering. Once the trigger mechanism is activated, the stored energy automatically drives the complete injection sequence to completion. This preliminary energy storage ensures that the injection cannot be prematurely stopped, as the spring's stored energy continues to drive the plunger until the full dose is delivered or the mechanism is designed to stop.
Solution Approach 2:
The mechanism includes a trigger system that, once activated, commits the spring to complete its energy discharge cycle. This beforehand commitment prevents premature release or incomplete injection, as the triggered mechanism is designed to complete the full injection sequence or be recovered as a unit, ensuring reliable dose delivery while maintaining simple operation.
4Ease of operation
If electro-mechanical or fully electronic components are used, then ease of operation improves through automation, but ease of repair deteriorates due to battery replacement and component fragility
Solution Approach 1:
The patent replaces electro-mechanical and electronic components with a purely mechanical spring-driven system. This eliminates batteries, motors, circuit boards, and electronic sensors that require replacement or repair. The mechanical spring system provides automation while being inherently repairable through simple mechanical means or replacement of the entire autoinjector unit, dramatically improving ease of repair while maintaining automated operation.
Solution Approach 2:
The autoinjector is designed as a single-use disposable device with a simple mechanical construction. Rather than creating a complex reusable device requiring repair of electronic components, the entire unit is designed to be discarded after one use. This approach eliminates all repair considerations while maintaining automated injection delivery, as the low cost of the disposable unit makes repair economically unnecessary.
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 ensures consistent and reliable injection delivery, suitable for users with limited dexterity, and reduces complexity by 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
Implementation Method 2
The plunger includes a transverse beam, a piston rod extending from the transverse beam, and at least one leg extending from the transverse beam and parallel to the piston rod. The at least one leg includes a distal foot adapted to support the at least one drive spring. The at least one leg includes a ratchet face having a plurality of teeth. In an exemplary embodiment, an autoinjector according to the present disclosure further includes at least one resilient tongue disposed in the case and having a hook adapted to engage a tooth on the ratchet face.
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.