Fluid Injection Device with Automatic Needle Sleeve
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Solution Overview
Problem
Existing fluid injection devices, particularly pre-filled syringes with safety devices, are complex to manufacture and assemble, and their reliability and safety features are not consistently effective in preventing needle injuries post-use.
Innovation Solution
A fluid injection device design featuring a syringe with a piston and needle, a movable sleeve that automatically covers the needle post-injection via a compressed spring and radially-deformable tabs, ensuring safety and simplicity in manufacturing and assembly, with a secondary piston for fluid integrity and a conical hollow member for tab deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional outer sleeve safety device is assembled around the syringe, then needle coverage is achieved, but manufacturing complexity and assembly complexity increase
Solution Approach 1:
The safety sleeve is merged with the syringe body through integral formation, eliminating the need for separate assembly of the safety component. The sleeve is formed as a single piece with the syringe body, reducing part count and assembly steps while maintaining the needle coverage function.
Solution Approach 2:
The syringe body is designed to serve multiple functions: it acts as both the fluid containment structure and the safety mechanism housing. The integrated sleeve becomes part of the syringe body structure, allowing the same component to provide both structural support and safety coverage functions.
2Reliability
If a traditional outer sleeve safety device is assembled around the syringe, then needle coverage is achieved, but assembly process becomes more complex
Solution Approach 1:
The safety sleeve and syringe body are combined into a single integrated component through integral formation. This eliminates the need for separate assembly operations, reducing assembly complexity and improving manufacturing efficiency while maintaining safety functionality.
Solution Approach 2:
The safety sleeve is pre-formed as an integral part of the syringe body during the molding process. This preliminary formation of the safety structure eliminates subsequent assembly steps and ensures consistent safety functionality without requiring additional assembly operations.
3Reliability
If radially-deformable tabs are snap-fastened in windows of the body, then the sleeve is blocked in non-projecting position, but the mechanism requires precise alignment
Solution Approach 1:
The tabs are designed as radially-deformable flexible elements that can elastically deform to engage with or disengage from the windows. This flexibility compensates for minor alignment variations and allows the tabs to snap into place reliably without requiring extremely tight manufacturing tolerances.
Solution Approach 2:
The windows in the syringe body are designed with curved or rounded profiles that match the deformation path of the radially-deformable tabs. This curved geometry facilitates smooth engagement and disengagement of the tabs, reducing the precision requirements compared to sharp-edged or flat interfaces.
4Extent of automation
If a hollow member deforms the tab radially inwards after injection, then the sleeve is automatically moved to projecting position, but the activation mechanism adds complexity
Solution Approach 1:
The hollow member is designed to automatically deform the tabs through its own structural characteristics after injection. The deformation is self-triggered by the injection process itself, eliminating the need for separate activation mechanisms, buttons, or external triggers. The system activates the safety sleeve automatically through its inherent design.
Solution Approach 2:
The radially-deformable tabs serve as an intermediary mechanism between the injection process and the sleeve activation. The tabs translate the injection event into the mechanical action needed to release and activate the safety sleeve, providing a simple mediation that avoids complex direct actuation mechanisms.
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 device ensures reliable and safe operation by automatically covering the needle post-injection, preventing injuries and simplifying manufacturing and assembly, while maintaining fluid integrity until actuation.
Implementation Method 1
said sleeve being in its non-projecting position before the injection device is actuated, and being urged, while in said non-projecting position, towards its projecting position by a compressed spring
Implementation Method 2
a hollow member that co-operates, after injection, with said at least one radially-deformable tab so as to deform it radially inwards, thereby causing it to cease co-operating with its respective window of said body
Data Source
AI summary
A fluid injection device including a syringe with a body (1), a piston (3), and a needle (2) with an injection tip (20); a piston rod (5); and a sleeve (10) around the syringe and axially movable between a non-projecting position in which said sleeve (10) does not cover the injection tip (20) and a projecting position. The sleeve (10) urged, while in said non-projecting position, towards its projecting position by a spring (30). The sleeve (10) has an inner portion (11) extending inside the body, and an outer portion (12) extending outside the body (1), the inner portion (11) including a radially-deformable tab (110) snap-fastened in a window (6) of the body (1), blocking the sleeve in its non-projecting position. A hollow member (40) co-operates, after injection, with the radially-deformable tab (110), so that after the fluid is injected, the sleeve is moved automatically towards its projecting position.