Pneumatic Damping for Automatic Injection Device

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Solution Overview

Problem

Existing spring-driven injection devices exert high forces that can damage the syringe plunger and other components during medication ejection, leading to potential fractures and sticking issues due to initial impact.

Innovation Solution

Incorporating a damping mechanism, such as a pneumatic damper, to reduce the kinetic energy imparted by the drive member to the syringe plunger during the initial operating phase, thereby minimizing impact forces and preventing damage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If a strong compression spring is used to drive the plunger, then the medication ejection force is improved, but the impact force on the plunger and components increases causing damage

Engineering Contradiction:

Improvemedication ejection forceVSAvoidimpact force damage

Core Design Contradiction:

ForceVSObject-affected harmful factors

Solution Approach 1:

A pneumatic damper is introduced between the drive member and plunger to cushion the impact before it occurs. The damper absorbs the kinetic energy from the compression spring's sudden release, preventing direct transmission of impact forces to the plunger and other components while still enabling effective medication ejection.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The pneumatic damper acts as an intermediary element between the drive member and plunger. It mediates the force transmission by converting the sudden mechanical impact into controlled pneumatic pressure changes, thereby reducing harmful impacts while maintaining the necessary ejection force.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Speed

If the drive member is released suddenly from the cocked position, then the injection speed is improved, but the kinetic energy imparted to the plunger causes damage

Engineering Contradiction:

Improveinjection speedVSAvoidcomponent durability

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The pneumatic damper is positioned to engage before the plunger reaches high speeds, cushioning the initial kinetic energy release. This allows the plunger to accelerate sufficiently for rapid injection while preventing excessive forces that would damage components.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The damper utilizes pneumatic principles to control the plunger's acceleration. By introducing a compressible gas medium between the drive member and plunger, the system achieves controlled pressure buildup that limits peak forces while maintaining the speed required for effective injection.

Inventive Principle:

Principle #29Pneumatics and hydraulics

3Object-affected harmful factors

If a damping mechanism is added to reduce kinetic energy, then the risk of damage is improved, but the device complexity increases

Engineering Contradiction:

Improvekinetic energy damageVSAvoiddamping mechanism structure

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The pneumatic damper uses a simple gas-filled chamber with a piston to achieve damping, avoiding the need for complex mechanical shock absorbers or multiple moving parts. The compressible nature of gas provides inherent damping with minimal structural complexity.

Inventive Principle:

Principle #29Pneumatics and hydraulics

Solution Approach 2:

The damper works by changing the physical state and pressure parameters of a gas medium rather than adding complex mechanical elements. By controlling gas pressure and compression, the system achieves kinetic energy reduction through parameter changes in the pneumatic medium.

Inventive Principle:

Principle #35Parameter changes

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 mechanism reduces the risk of damage to the syringe and device components by smoothing the injection process, ensuring reliable and safe medication delivery without premature ejection of medication.

Implementation Method 1

a pneumatic damper, to reduce the kinetic energy imparted by the drive member to the syringe plunger during the initial operating phase

Methodology Applied

Scientific EffectGas compression: Compression

Data Source

PatentUS9119920B2Automatic injection device with pneumatic damping

Publication Date: 2015.09.01 OWEN MUMFORD

AI summary

An injection device for use with a syringe having a syringe body, a needle coupled thereto, and a plunger moveable through the body to eject medication from the syringe through the needle, includes a housing defining an inner space for holding a syringe and facilitating movement thereof from a first position in which the needle is contained fully within the housing and a second position in which the needle projects from the housing, and a drive member located within the inner space so that in use the drive member can engage the plunger of a syringe held within the housing. The device further includes a force applicator located within the inner space for providing a force to the drive member so as to move the syringe from the first to the second position and thereafter to move the plunger through the syringe body, a trigger mechanism, and a damper.