Injection Device Damping System for Force Attenuation
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Solution Overview
Problem
Existing injection devices face challenges in managing the high forces and velocities generated by spring-loaded mechanisms, leading to undesirable sounds and tactile sensations during medicament delivery, particularly for larger dose volumes, which can result in patient discomfort and increased risk of delivery errors.
Innovation Solution
Incorporating a damping system within the injection device that attenuates the force and velocity of the drive spring, using frictional engagement mechanisms such as O-ring or deformable material designs to control the force exerted during needle deployment and plunger movement, thereby reducing recoil and internal assembly forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a high energy drive spring is used to generate greater force for larger dose volumes, then the driving force is improved, but high velocities and impacts (shock load) cause undesirable sound and tactile sensation
Solution Approach 1:
A damper component is introduced into the drive mechanism that provides frictional engagement with the plunger rod during the initial extension of the drive spring. This frictional force acts as a cushioning effect that attenuates the high velocities and impacts generated by the high energy drive spring, thereby reducing undesirable sound and tactile sensations while maintaining the necessary driving force for larger dose volumes.
2Length of moving object
If a high energy drive spring is used to allow for longer travel of drive components, then the delivery capacity is improved, but the maximum force in fully compressed state causes high velocities and impacts
Solution Approach 1:
The damper component with its frictional engagement surface is positioned to engage the plunger rod at the beginning of the drive spring extension. This provides beforehand cushioning that controls the initial high velocity and impact generated by the compressed spring, allowing the plunger rod to travel the required long distance for larger dose volumes without experiencing harmful shock loads.
3Force
If more material is used to absorb the driving force of the drive spring, then the force attenuation is improved, but the device complexity and material usage increase
Solution Approach 1:
A damper component serves as an intermediary element between the drive spring and the plunger rod. This single component with a frictional engagement surface provides the necessary force attenuation through controlled friction, avoiding the need for complex multi-component absorption systems while effectively reducing the driving force to acceptable levels.
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 damping system enhances patient acceptance by minimizing discomfort and reducing delivery errors, allowing for more controlled and precise medicament delivery across various volume ranges without the need for excessive material or force, improving the overall usability of the device.
Implementation Method 1
The damper is configured to frictionally engage a surface of the first drive component during movement of the drive component relative to the damper
Implementation Method 2
plastic rib compression deformation-based designs
Implementation Method 3
circumferential tensile deformation-based designs
Data Source
AI summary
An injection device includes a drive spring within the housing, a first drive component that transfers drive from the drive spring to a plunger disposed within a medicament container, and a damper concentrically arranged with respect to the first drive component. The damper is longitudinally fixed relative to the housing. The first drive component moves along the longitudinal axis relative to the damper under the influence of the drive spring. The damper frictionally engages a surface of the first drive component during movement of the drive component relative to the damper. A method of manufacturing the injection device is also described.