Passive Needle Shielding Assembly With Preloaded Plastic Spring
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Solution Overview
Problem
Existing needle safety assemblies face issues with metal springs causing assembly problems in high-speed processes and plastic springs losing preload over time, leading to ineffective needle shielding.
Innovation Solution
A safety needle assembly with a tubular housing, needle mount, and integral spring mechanism that rotates the needle to a shielding position upon detachment from the medical injector, using a blocking means to maintain the needle in an operative position until detachment, and an audible verification mechanism to ensure correct attachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metal springs are used to maintain preload force, then the spring capacity is maintained, but assembly problems occur during high-speed assembly processes
Solution Approach 1:
The patent uses a plastic spring instead of a metal spring. The plastic spring is designed to be used once and then discarded, eliminating the need for complex assembly and disassembly operations. This resolves the contradiction by sacrificing the durability of the spring to enable high-speed assembly processes.
Solution Approach 2:
The patent replaces the traditional metal mechanical spring with a plastic spring that utilizes elastic deformation of the material. This substitution allows for simpler assembly processes while maintaining the necessary spring function, thereby improving assembly speed without significantly compromising reliability.
2Productivity
If plastic springs are used to enable high-speed assembly, then assembly process is simplified, but preload force is lost over time
Solution Approach 1:
The patent incorporates a blocking device that is set during assembly to immediately engage and maintain the spring in a loaded position. This preliminary action ensures that the preload force is established and maintained from the moment of assembly, preventing the gradual force loss that would otherwise occur with plastic springs over time.
Solution Approach 2:
The blocking device acts as an intermediary mechanism between the plastic spring and the needle assembly. It transfers and maintains the elastic force generated by the plastic spring, ensuring that the preload force is reliably transmitted to the needle throughout the storage and use period, thereby compensating for the inherent tendency of plastic springs to lose force over time.
3Force
If spring is preloaded in a loaded position, then needle shielding force is generated, but the spring material must maintain capacity during prolonged storage
Solution Approach 1:
The blocking device is configured to engage the needle assembly in a predetermined position that immediately generates the required shielding force when the device is assembled. This preliminary positioning action ensures that the spring is loaded and the needle is positioned for shielding before the device is stored, thereby maintaining the necessary force throughout the storage period without requiring continuous spring activation.
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
Ensures reliable automatic needle shielding without user intervention, reducing the risk of needle stick injuries and assembly issues, while maintaining spring preload during prolonged storage.
Implementation Method 1
the spring means is arranged to urge movement of the needle to the shielding position... the spring means is integral to a mounting member... the spring means and the needle mount are arranged at a set position relative to each other... use of the safety needle assembly with the medical injector causes a shift from the set position; said shift moves one of the mounting member or the needle mount relative to the other to enable the spring means to rotate the needle to the shielding position
Data Source
AI summary
The safety needle assembly comprises a needle/cannula (112) mounted in a tubular housing (120). The needle has a patient end (114) and a non-patient end and an aim of the invention is to provide passive needle stick protection at the non-patient end. A further aim is to increase the reliability and to reduce fatigue on the spring means prior to use. The cannula (112) is located within the needle mount (160) which is located within the tubular housing (120). The shielding sleeve (130) provides the blocking means which retains the alignment of the cannula (110) along the longitudinal axis of the tubular member (120). In particular, the blocking means is arranged to counteract the pivoting force of the spring or an ability of the cannula to freely rotate in order to retain the cannula (112) in an operative position. In the present invention, the spring (170) and the needle mount (160) are arranged at a set position and the use of the safety needle assembly (110) with the medical injector (111) causes a shift from the set position. This shift enables the spring (170) to then rotate the needle (112) to the shielding position when the safety needle assembly (110) is detached from the medical injector (111).