Retractable Needle Syringe Piston Spring Nesting
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Solution Overview
Problem
Syringes with retractable needles face issues with sealing problems and space consumption due to the arrangement of the spring mechanism in the distal part of the barrel, and there are challenges with locking the needle within the Luer adapter and within the syringe, particularly with the compression spring tilting due to insufficient guidance and support.
Innovation Solution
The syringe design incorporates a piston with a holding ring on its inner surface to engage an outer flange of the spring sleeve, a needle holder with a circular protrusion for secure engagement within the male Luer adapter, and a compression spring with ring elements at both ends to improve the mounting and securing of the needle, along with a spring tensioning element that secures the spring in a compressed state until actuation, allowing the needle holder and needle to retract into the barrel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the spring mechanism is arranged in the distal part of the barrel, then the needle retraction function is achieved, but sealing problems and space consumption increase
Solution Approach 1:
The spring mechanism is nested within the piston structure. The spring sleeve is received by the piston, and the compression spring is housed within the spring sleeve, creating a compact nested arrangement that fits within the piston volume without requiring additional distal barrel space.
Solution Approach 2:
The spring mechanism is repositioned from the distal barrel region to the proximal piston region, utilizing the longitudinal dimension of the piston to accommodate the spring assembly. This dimensional relocation resolves the space conflict in the distal barrel while maintaining retraction functionality.
2Device complexity
If the compression spring is used without sufficient guidance, then the spring mechanism is simple, but the spring tilts and the needle locking becomes unreliable
Solution Approach 1:
The spring sleeve acts as an intermediary guidance element between the compression spring and the piston. It provides a confined pathway that guides the spring's expansion and contraction, preventing lateral tilting while maintaining a relatively simple overall structure.
Solution Approach 2:
The spring sleeve functions as a flexible cylindrical shell that constrains the compression spring within its boundaries. This thin-walled structure provides sufficient guidance to prevent spring tilting while adding minimal structural complexity.
3Volume of stationary object
If the spring mechanism is relocated to the piston, then sealing problems and space consumption are reduced, but the mounting and securing of the needle requires improvement
Solution Approach 1:
The needle securing function is segmented into distinct engagement features: the circular protrusion on the needle holder for Luer adapter engagement, and the circular recess for spring sleeve engagement. This segmentation ensures reliable mounting and securing without complicating the overall design.
4Reliability
If the spring sleeve engagement with needle holder is improved, then needle retraction reliability is enhanced, but the device complexity increases
Solution Approach 1:
Instead of having the spring sleeve actively grip the needle holder, the design uses a passive engagement where the circular protrusion on the needle holder fits into the circular recess in the spring sleeve. This inverted approach achieves reliable engagement through simple geometric complementarity rather than complex active gripping 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
This design enhances the secure locking and retraction of the needle, preventing accidental exposure and ensuring safe disposal by effectively utilizing the space within the syringe barrel while minimizing sealing issues and preventing the spring from tilting, thus ensuring safety and efficient operation.
Implementation Method 1
a spring mounted on the spring sleeve
Implementation Method 2
the spring element comprises a compression spring with at least one ring element at the ends
Data Source
Figure 1~2
Figure 3~6
Figure 7~12
AI summary
The invention relates to a syringe with a retractable needle comprising a barrel (2) having a nozzle (19) integrated in a male Luer adapter element (26); a piston (3) slidably arranged in the barrel (2) and coupled to a sealing element (16), said sealing element (16) having a central channel (20); a needle assembly comprising a needle (4), a needle holder (6) and a female Luer adapter element (7); a spring assembly arranged in the piston (3) comprising a spring sleeve (12), a spring (13) mounted on the spring sleeve (12), a spring tensioning element (14) located on the spring sleeve (12) and held in position by the piston wall, and a plunger (15) mounted within the spring sleeve; and a piston cap (10); said piston (3) being coupled to the sealing element (16) by means of the spring tensioning element (14); said spring sleeve (12) being held in position within the piston (3) by a ring element (18) protruding from the inner wall of the piston (3) and supporting the proximal end of the spring sleeve (12), the spring sleeve extending into the channel (20) of the sealing element (16) to the distal end thereof; said spring sleeve (12) comprising at its distal end a circular protrusion (21) on the inside designed to engage a circular recess (22) at the proximal end of the needle holder (6); wherein the piston (3) comprises a holding ring (11) on its inner surface designed to engage with an outer flange (17) of the spring sleeve (12) after actuation of the spring (13).