Syringe Plunger Locking Mechanism for Contamination Prevention
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Solution Overview
Problem
Existing syringes face challenges in preventing the plunger from being pulled out when the outer cylinder is filled with liquid, leading to potential contamination and spillage, and the movement of the plunger during filling is not easily estimable.
Innovation Solution
A syringe design featuring a stopper member with a hook that can be easily locked and unlocked by pinching operating strips, allowing the plunger to move towards the proximal end during filling while preventing movement in a filled state, and a supporting portion to ensure reliable locking and easy operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a tooth portion and movement stop device are used to prevent plunger movement, then the plunger is locked in the filled state, but the plunger cannot be easily moved during filling operation
Solution Approach 1:
The stopper member is designed with a flexible body that can dynamically change its state between locked and unlocked positions. The elastic portion bends to allow plunger movement during filling, then automatically returns to lock the plunger in the filled state, providing adaptive behavior based on operational phase
Solution Approach 2:
The stopper member automatically performs the locking function without requiring additional operations from the user. After the plunger is pushed to fill the syringe, the elastic portion of the stopper member automatically returns to its original position to engage the tooth portion, locking the plunger in place without manual intervention
2Ease of operation
If the plunger is allowed to move freely during filling, then filling operation is easy, but the plunger may be accidentally pulled out causing contamination or spillage
Solution Approach 1:
The locking mechanism transitions from a static locked state to a dynamic state where the elastic portion can bend to allow plunger movement during filling, then automatically returns to lock. This dynamic behavior allows free movement during filling while preventing accidental pull-out after filling
Solution Approach 2:
The stopper member is positioned and configured to engage the tooth portion before filling begins, creating a preliminary lock that prevents accidental pull-out. The mechanism is designed to maintain this protective lock until filling is complete, at which point the lock is automatically released
3Reliability
If a complex locking mechanism is used to prevent plunger movement, then reliability is improved, but device complexity increases
Solution Approach 1:
The stopper member integrates multiple functions into a single component: it acts as both the sealing element for the outer cylinder and the locking mechanism for the plunger. The elastic portion serves both as the flexible element for automatic locking and as the actuator that engages/disengages the tooth portion, eliminating the need for separate locking components
Solution Approach 2:
The stopper member automatically performs the locking and unlocking functions without requiring additional actuators, springs, or complex mechanisms. The elasticity of the stopper member itself provides the restoring force needed for automatic locking, eliminating the need for separate spring mechanisms or power sources
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
This design enhances operational efficiency by allowing easy filling of the syringe while preventing contamination and spillage, with automatic relocking of the hook after use, improving handling efficiency and reducing manufacturing costs.
Implementation Method 1
a stopper member (24) comprising: a body (24a) having a flexible material; a hook (98) formed integrally with the stopper member (24) and configured to lock the tooth portion (90a) of the plunger (22)
Data Source
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AI summary
The syringe (10) includes first and second outer cylinders (14, 16) having a flowing port 26 which allows liquid to flow therethrough at a distal end, and a plunger (22) inserted from the proximal side of the outer cylinder (14, 16). The syringe (10) includes a tooth portion (90) provided along the direction of movement of the plunger (22), and a hook (98) configured to lock the tooth portion (90) at a predetermined locking position and prevent the movement of the plunger (22) in the direction toward the proximal end. The hook (98) retracts from the locking position in association with the unlocking operation and restores automatically to the locking position after the unlocking operation.