Syringe Automatic Needle Retraction Mechanism
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Solution Overview
Problem
Existing syringes require manual retraction of the injection needle after use, posing a risk of accidental needle sticks during the locking process, as they lack an automatic mechanism for needle retraction and locking.
Innovation Solution
A syringe design featuring a coil spring and spring holder mechanism that automatically retracts and locks the injection needle into the sleeve after drug administration, utilizing a finger hook flange and resilient engagement pieces for safe operation without manual re-holding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If manual needle retraction is performed after administration, then the syringe structure can be simple, but the risk of accidental needle sticks increases
Solution Approach 1:
The syringe automatically retracts the needle using a coil spring mechanism that activates when the plunger is pushed beyond the engagement position. The system serves itself by using the administration force to trigger the retraction sequence, eliminating the need for manual retraction operations and associated safety risks
Solution Approach 2:
The coil spring is pre-loaded in a compressed state by the spring holder during the administration phase. When the plunger exceeds the engagement position, the pre-stored elastic energy is released to automatically retract the needle, performing the safety action before the user can accidentally contact the needle
2Reliability
If automatic needle retraction mechanism is added, then safety during needle retraction is improved, but the syringe structure becomes complex
Solution Approach 1:
The automatic retraction mechanism is merged with the existing plunger and sleeve structures. The spring holder integrates with the sleeve, and the retraction force is applied through the existing plunger movement, combining multiple functions into unified components rather than adding separate complex mechanisms
Solution Approach 2:
The spring holder acts as an intermediary component that stores and releases elastic energy to drive the retraction. This mediator component simplifies the overall mechanism by using a single spring-based system rather than requiring complex motors or additional actuators
3Productivity
If the sleeve is held at engagement position during administration, then liquid drug can be administered, but the needle cannot be automatically retracted
Solution Approach 1:
The sleeve transitions from a static engaged position during administration to a dynamic retracted position after administration. The system is designed to be stable during drug delivery but becomes unstable and automatically transitions to the retracted state when the plunger exceeds the engagement position, enabling automatic needle retraction
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 syringe ensures safe automatic retraction and locking of the needle, reducing the risk of accidental injuries during the needle retraction process by allowing a pushing operation to initiate the needle's accommodation, thus enhancing user safety.
Implementation Method 1
a coil spring provided between the sleeve and the syringe barrel for biasing the sleeve toward the accommodation position
Data Source
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AI summary
It is an object of the present invention to provide a syringe which is capable of preventing an accident such that a patient inadvertently sticks her/his hand with an injection needle when improperly performing a needle retracting operation. A sleeve (10) is fitted around a syringe barrel (2) so as to be axially movable from an administration position such that the injection needle (5) projects to a distal side to an accommodation position such that the injection needle (5) is accommodated. A coil spring (16) for biasing the sleeve (10) toward the accommodation position is provided between the sleeve (10) and the syringe barrel (2), and is held in a compressed state in a spring holder (17). The spring holder (17) is disposed in association with the syringe barrel (2) so as to release the coil spring by further pushing the syringe barrel (2) to the distal side after completion of the administration of a liquid drug. The sleeve (10) is axially engaged with the syringe barrel (2) so as to be locked at the accommodation position when being moved to the accommodation position by a biasing force of the coil spring (16).