Autoinjector Torsion Spring Design for High-Viscosity Injection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional spring-loaded autoinjectors face challenges with high initial forces, weak forces during later stages of injection, and complex designs, leading to patient discomfort, potential device breakage, and inefficient delivery of high-viscosity medications.
Innovation Solution
A novel injector apparatus utilizing a spring mechanism that tailors energy release for controlled needle insertion and optimized medicament delivery, featuring a combination of torsion and compression springs to provide a nearly constant force profile, reducing initial force and ensuring smooth injection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a compression spring is used to power the expulsion of medication, then the injection can be delivered, but the initial force is too great causing patient discomfort and potential device breakage
Solution Approach 1:
The patent applies dynamics by transitioning from a static compression spring to a dynamic torsion spring system where the spring unwinds progressively. The torsion spring converts rotational motion to linear motion through a screw mechanism, dynamically adjusting the force delivery profile to reduce initial force while maintaining adequate force throughout the injection process.
Solution Approach 2:
The patent changes the fundamental parameter of spring configuration from compression to torsion type. This parameter change fundamentally alters the force delivery characteristics, enabling a more favorable force profile that reduces peak initial force while maintaining sufficient force for complete medication expulsion.
2Use of energy by moving object
If a large amount of energy is stored in the spring to reliably deliver high-viscosity fluids, then the injection can be completed, but the device becomes relatively large or complex
Solution Approach 1:
The torsion spring serves multiple functions: it stores energy for the entire injection process, drives the plunger rod through rotational-to-linear conversion, and provides a compact structure that integrates these functions. This multi-functionality reduces device complexity compared to systems requiring separate mechanisms for each function.
Solution Approach 2:
The patent replaces the traditional compression spring mechanical system with a torsion spring and screw mechanism. This substitution achieves the same energy storage and force delivery objectives in a more compact and simpler configuration, particularly effective for high-viscosity fluid delivery.
3Device complexity
If the same spring is used to insert the needle as to deliver the medicament, then the device is simpler, but the injection depth control becomes difficult due to rapid needle movement
Solution Approach 1:
The torsion spring's gradual unwinding mechanism creates a dynamic force profile that naturally controls needle insertion speed. The rotational-to-linear conversion through the screw mechanism provides inherent speed regulation, preventing rapid needle movement while maintaining simple device architecture.
4Productivity
If excessive and sudden forces are applied to inject high-viscosity fluid, then the injection can be completed, but the injector and/or syringe could break
Solution Approach 1:
Changing from compression to torsion spring fundamentally alters the force application parameters. The torsion spring delivers force progressively through rotational unwinding, preventing excessive and sudden force spikes that could damage the injector or syringe components while still achieving complete medication delivery.
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 solution achieves reduced needle insertion force, minimized patient discomfort, lower risk of device breakage, and efficient delivery of high-viscosity medications with a simpler and more compact design.
Implementation Method 1
A novel injector apparatus utilizing a spring mechanism that tailors energy release for controlled needle insertion and optimized medicament delivery, featuring a combination of torsion and compression springs to provide a nearly constant force profile
Implementation Method 2
a screw having helical threads, a nut having a pin or pins that ride in the threads of the screw
Data Source
Figure 1~2B
Figure 2A
Figure 3
AI summary
The invention provides methods and apparatus for injecting a medicine, especially a highly viscous medicine. Conventional methods and apparatus for injecting viscous medicines suffers from a variety of problems such as excessive force during the initial needle insertion and initial injection. In an inventive method, during the initial phase of the injection, energy is stored in a torsion spring that is subsequently released during a later stage of the injection. The present invention also provides for an improved autoinjector; especially via the use of a combination compression and torsion spring that powers the injection through controlling force applied to plunger via a screw flange or nut having pins that ride in a prescribed path down the length of the autoinjector.