Injection Device End of Dose Indicator Mechanism
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Autoinjector devices lack a tactile indication for users when a dose is completely delivered, which is not present in manual devices, making it difficult for users to confirm the end of the dose.
Innovation Solution
An injection device with a locking mechanism that includes a reaction component, a plunger, and a drive spring, where the reaction component provides a reaction surface for the drive spring, allowing for an audible indication of the end of dose by impacting a rear cap upon rearward movement, triggered by a predefined forward movement of the plunger.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a locking mechanism with reaction component is added to provide audible end-of-dose indication, then user safety and awareness are improved, but device complexity increases
Solution Approach 1:
The reaction component is nested within the existing firing mechanism structure, utilizing the space between the drive spring and the syringe assembly. The component integrates with the plunger rod and housing without requiring separate external mechanisms, thus providing the audible indication function while minimizing additional structural complexity.
Solution Approach 2:
The reaction component utilizes the existing drive spring force and plunger movement to automatically generate the audible click indication at end-of-dose. No external power source or additional actuation mechanism is required - the system uses its own operational movements to trigger the indication, eliminating the need for separate control systems.
2Loss of information
If the reaction component is designed to rotate and release from stop feature, then end of dose indication is achieved, but manufacturing precision requirements increase
Solution Approach 1:
The reaction component is designed to rotate through a limited angular range during the plunger's forward movement, releasing from the stop feature at a specific point in this periodic cycle. This controlled rotational movement provides a clear, repeatable click indication that can be manufactured within standard tolerances without requiring ultra-precise positioning.
Solution Approach 2:
The stop feature acts as an intermediary element between the reaction component and the housing, providing a simple geometric reference point for the rotation release. This intermediary allows the reaction component to rotate and release without requiring direct precision machining between multiple moving parts, as the stop feature can be a simple fixed protrusion or ledge.
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
Provides a reliable audible indication of the end of dose, enhancing user safety and operability by ensuring the user is aware when the dose is complete, preventing over-administration.
Implementation Method 1
a drive spring located between the reaction component and the plunger for driving the plunger forwards upon activation of the injection device
Implementation Method 2
allowing the reaction component to be driven in a rearward axial direction by the drive spring until it impacts against said body or a component secured to the body to thereby emit an audible indication of an end of dose
Data Source
AI summary
Disclosed is an injection device including a body for receiving a syringe, a firing mechanism including a reaction component, a plunger configured to be axially displaced in a forward direction relative to the reaction component, and a drive spring located between the reaction component and the plunger for driving the plunger forwards upon activation of the injection device, wherein the reaction component provides a reaction surface for the drive spring. The device further includes a locking mechanism for locking the reaction component in a first axial position within the body, the locking mechanism being configured to release the reaction component upon a predefined forward movement of the plunger thereby allowing the reaction component to be driven in a rearward axial direction by the drive spring until it impacts against the body or a component secured to the body to thereby emit an audible indication of an end of dose.