Autoinjector Needle Guard Locking Mechanism
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current medicament delivery devices, such as autoinjectors, pose a risk of injury to users due to exposed needles after use, as there is no effective mechanism to prevent the needle guard from being moved back to the retracted position, exposing the needle again.
Innovation Solution
A subassembly featuring a cover structure with a guiding member that slides through slots in both the housing and cover structure, locking into a position once the device is used, preventing the cover structure from moving back to the retracted position and thus securing the needle in the extended position, thereby preventing user injury.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the cover structure is made movable to allow retraction for needle exposure, then ease of operation is improved, but safety deteriorates due to risk of accidental needle exposure after use
Solution Approach 1:
The guiding member is pre-configured with a ratchet mechanism that allows the cover structure to be moved in the retraction direction (needle exposure) but prevents movement in the extension direction (needle coverage) after a certain point. This preliminary mechanical design ensures that once the needle is exposed for use, it cannot accidentally be covered again, while still allowing intentional exposure when needed.
Solution Approach 2:
The guiding member acts as an intermediary component between the cover structure and the housing. It mediates the movement of the cover structure by providing controlled guidance through slots, allowing movement in one direction while blocking movement in the opposite direction. This intermediary mechanism resolves the contradiction by enabling ease of operation while preventing harmful accidental movements.
2Object-affected harmful factors
If a locking mechanism is added to prevent cover structure movement after use, then safety is improved, but device complexity increases
Solution Approach 1:
The locking function is segmented into a separate guiding member component with integrated ratchet teeth, rather than adding a complex multi-part locking mechanism. The guiding member is divided into functional segments (slots for movement, teeth for locking) that work together simply. This segmentation achieves the safety function with minimal added complexity.
Solution Approach 2:
The guiding member's ratchet mechanism is designed to be self-locking through its geometric configuration. The inclined surfaces and teeth automatically engage to prevent reverse movement without requiring additional actuators, springs, or complex control systems. The mechanism serves itself by using the movement force to engage the locking feature, thereby improving safety without significantly increasing device complexity.
Data Source
AI summary
The present disclosure generally relates to medicament delivery devices such as autoinjectors, and particularly concerns a subassembly adapted to prevent injuries to a user caused by a medicament delivery member at a proximal end of the medicament delivery device.