Shroud Deployment Assembly for Automatic Injection Devices
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Solution Overview
Problem
Conventional automatic injection devices often experience failures in shroud deployment, including complete or incomplete deployment, and delayed deployment, which can lead to accidental needle stick injuries due to exposed needles.
Innovation Solution
The design incorporates a shroud deployment assembly with a syringe carrier and a tubular member, where the shroud moves within a constrained space to ensure complete and automatic deployment, and includes features like a chamfered edge and flange configurations to minimize pinching effects and resist accidental retraction, ensuring the shroud remains in the extended position to protect the needle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the shroud is designed to move within a constrained space between the housing and syringe carrier, then the shroud deployment reliability is improved, but the device complexity increases due to additional structural constraints
Solution Approach 1:
The shroud is divided into a tubular member and separate arms that can move independently within the constrained space. The arms are segmented to allow individual movement past the flange while remaining connected to the tubular member, enabling reliable deployment without requiring the entire shroud to move as a single complex unit.
Solution Approach 2:
The constrained space between the housing and syringe carrier acts as an intermediary mechanism that guides and controls arm movement. This intermediate space provides a defined path for the arms to traverse during deployment, ensuring reliable operation without requiring complex external control mechanisms.
2Object-affected harmful factors
If the arms of the shroud are made wider to improve needle protection, then the safety is improved, but the pinching effect during deployment increases causing deployment failure
Solution Approach 1:
The arms are designed with varying widths at different locations - wider at the distal end to provide adequate needle protection, and narrower at the proximal end to reduce pinching during deployment. This local variation in geometry allows the arms to provide sufficient coverage while顺利通过 the constrained deployment space.
Solution Approach 2:
The arms are designed to dynamically adjust their position and orientation during deployment. They rotate and move through the constrained space in a controlled manner, allowing the distal ends to maintain width for protection while the proximal portions pass through the flange opening without excessive pinching.
3Ease of operation
If the shroud is designed to automatically deploy after injection, then the ease of operation is improved, but the risk of accidental deployment increases
Solution Approach 1:
The shroud is pre-loaded in a retracted position that blocks the needle, and the deployment mechanism is designed with a threshold trigger force. Accidental forces below this threshold cannot initiate deployment, while the intended injection action generates sufficient force to overcome the threshold and trigger automatic shroud retraction.
Solution Approach 2:
The deployment mechanism utilizes parameter changes in the injection process - specifically the pressure and force generated during needle insertion and injection. These parameters naturally exceed the deployment trigger threshold, ensuring automatic shroud retraction occurs only during proper device operation and not during accidental handling.
Data Source
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AI summary
Exemplary embodiments provide automatic injection devices in which a shroud is automatically deployed to protectively sheath a needle after an injection is performed. Exemplary embodiments also provide shroud deployment assemblies including a shroud and a syringe carrier that, when cooperatively configured in an automatic injection device, ensure that the shroud is automatically and completely deployed after an injection is performed using the automatic injection device. Exemplary embodiments are also configured to ensure that, once the shroud is deployed to an extended position to sheath the needle, accidental forces applied to the shroud do not succeed in subsequently retracting the shroud to a retracted position in which the needle would become exposed.