Gas Spring Injection Device for Constant Force Delivery
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Solution Overview
Problem
Current medicament injection devices face challenges with compression springs providing variable force throughout the injection process, leading to potential device breakage and inadequate penetration, especially with high viscosity medicaments, and existing solutions for constant force, such as gas springs, are not suitable for needle-based delivery systems.
Innovation Solution
The use of a gas spring with a matter-filled housing system, a piston, and a piston rod provides a consistent damping force along the entire stroke length, allowing for smoother and controlled medicament delivery, reducing device length and increasing grip comfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a compression spring is used to drive the plunger rod, then the device structure is simple and economical, but the spring force decreases linearly with extension, requiring over-dimensioning for high viscosity medicaments and risking device breakage
Solution Approach 1:
The patent replaces the mechanical compression spring with a gas spring system that uses compressed gas (nitrogen or carbon dioxide) stored in a reservoir. The gas expands through a regulator valve to provide controlled, consistent force throughout the plunger rod's stroke, eliminating the linear force decay characteristic of compression springs while maintaining structural simplicity.
Solution Approach 2:
The patent changes the physical state and properties of the driving force from a mechanical spring (solid) to a compressed gas (fluid). By adjusting gas pressure, temperature, and volume parameters, the system achieves constant force output throughout the injection stroke, unlike the compression spring whose force parameter naturally decays with extension.
2Volume of moving object
If a compression spring is used, then the device is compact, but the highest force at the beginning of the stroke may break the glass cartridge or syringe
Solution Approach 1:
The gas spring system is designed to provide controlled, gradual force expansion from the beginning of the stroke, preventing sudden force spikes that could break the glass cartridge or syringe. The regulator valve and gas expansion characteristics inherently cushion the initial force application, eliminating the need for additional protective components.
3Force
If a compression spring is over-dimensioned to handle high viscosity medicaments throughout the whole stroke, then adequate penetration force is available, but the device becomes larger and more complex
Solution Approach 1:
The gas spring system provides consistent force throughout the entire plunger rod stroke without requiring over-dimensioning. The compressed gas expands at controlled rates, maintaining adequate penetration force for high viscosity medicaments while keeping the device compact, as the force consistency eliminates the need for excessive spring pre-compression or larger dimensions.
4Force
If gas springs are used in needle-less delivery devices, then constant force is provided, but the devices require high driving pressure without damping and are painful for patients
Solution Approach 1:
The gas spring system is configured with different local characteristics: high pressure and constant force during the needle penetration phase, then transition to damped, controlled force during the medicament injection phase. The regulator valve and gas expansion characteristics allow local optimization of force properties for different stages of the injection process, ensuring patient comfort while maintaining penetration capability.
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 gas spring system ensures a consistent and controlled injection force, reducing the risk of device breakage and improving user experience by providing a uniform delivery of medicament, addressing the limitations of compression springs and previous gas spring implementations in needle-based devices.
Implementation Method 1
a gas spring having a matter-filled housing system, a piston and a piston rod connected to said drive means for driving said drive means with a constant and consistent damping force along its entire stroke length
Data Source
AI summary
The present invention relates to an injection device comprising a housing, a container containing medicament to be injected through a needle (34) attachable to said container, drive means (46) operatively acting on said container for injecting said medicament, the drive means comprising a gas spring (50), locking (57) and activating means (56) arranged to hold said gas spring in a loaded state, and when activated, releases said gas spring to inject said medicament.