Implant Syringe Snap Locking for Higher Holding Force
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Solution Overview
Problem
Existing implant syringes face challenges in providing a stable snap connection with a high holding force due to limited space for locking hooks, limiting the tensile strength to approximately 10 N, which is inadequate for secure implant delivery.
Innovation Solution
The design incorporates locking windows in diametrically opposed tabs of the needle guard and corresponding locking hooks on the spacer, creating a stable, virtually undetachable snap connection by applying pressure rather than stretching plastic, without increasing the outer sleeve's circumference or altering its appearance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If locking hooks with larger cross-section are used to increase holding force, then the snap connection stability improves, but the handling and visual appearance of the implant syringe deteriorates
Solution Approach 1:
The locking mechanism transitions from relying on plastic deformation in a limited 2D space to utilizing a 3D interlocking geometry where the locking hook engages with the locking window through lateral insertion and axial locking. This dimensional change allows for increased holding force without enlarging the outer circumference.
Solution Approach 2:
The locking connection is divided into distinct functional elements: the locking hook on the spacer, the locking window on the tabs, and the recesses for positioning. This segmentation allows each element to be optimized for its specific function while maintaining overall compactness.
2Reliability
If locking hooks with larger cross-section are used to increase holding force, then the snap connection stability improves, but the visual appearance of the implant syringe deteriorates
Solution Approach 1:
The solution moves the locking mechanism from a planar 2D configuration to a 3D spatial arrangement, allowing the locking hook to engage the locking window through lateral insertion while maintaining the outer circumference dimensions.
Solution Approach 2:
The locking hook is nested within the structure of the spacer, and the locking window is integrated into the tabs, creating a compact interlocking system that does not protrude or alter the external appearance of the implant syringe.
3Force
If the outer circumference of the inner sleeve is increased to accommodate larger locking hooks, then the holding force increases, but the handling of the implant syringe deteriorates
Solution Approach 1:
The locking mechanism utilizes lateral insertion and axial locking in three dimensions, eliminating the need to increase the outer circumference while achieving higher holding forces through the interlocking geometry of the hook and window.
Data Source
Figure 1a
Figure 1b~2b
Figure 3
AI summary
The implant syringe with a cannula 1, with an outer sleeve (3), with an inner sleeve (23) on which the outer sleeve sits and in which the cannula with the depot element is slidable, wherein the inner sleeve has axial slots, and wherein the inner sleeve is composed of a front needle guard (24) and a rear spacer (25) which are interlocked, is characterized in that a locking window (27) is formed in each of two opposing tabs (26) of the needle guard (24), that the spacer has two locking hooks (28) at corresponding positions, and that, in order to connect the two components, the tabs slide over the locking hooks of the spacer until the locking hooks engage in the locking windows.