Composite Needleless Injector Body for Igniter Pressure Strength

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Solution Overview

Problem

Needleless injectors using igniters for pressurization are compromised in user operability due to the need for high strength materials or large size to withstand pressure, which affects usability.

Innovation Solution

A needleless injector design incorporating a tubular metal reinforcing member embedded in a resin body, ensuring strength against igniter pressure while minimizing weight and size, using a combination of resin and metal materials.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If high strength materials such as metal are used for the injector body to withstand pressure from the igniter, then strength and safety are improved, but weight and size increase, compromising user operability

Engineering Contradiction:
Improvestrength against igniter pressureVSAvoidweight of injector
Core Design Contradiction:
StrengthVSWeight of moving object

Solution Approach 1:

The injector body is constructed as a composite structure combining a resin member with a metal reinforcing member. The resin member forms the main body providing lightweight structure, while the metal reinforcing member (tubular structure) is embedded within to provide localized strength against igniter pressure. This composite approach achieves the required strength without using solid metal throughout, thereby reducing overall weight and improving user operability.

Inventive Principle:
Principle #40Composite materials

2Strength

If the injector body is made large to accommodate stronger structural components, then strength and safety are improved, but device size increases, compromising user operability

Engineering Contradiction:
Improvestrength against igniter pressureVSAvoidsize of injector
Core Design Contradiction:
StrengthVSVolume of moving object

Solution Approach 1:

The composite structure of resin member plus embedded metal reinforcing member allows achieving high strength with compact dimensions. The metal tubular reinforcing member provides high strength-to-volume ratio, enabling the injector body to withstand igniter pressure without requiring large overall size, thus maintaining good user operability.

Inventive Principle:
Principle #40Composite materials

3Strength

If solid metal structure is used throughout the injector body, then strength is improved, but weight increases significantly, affecting user operability

Engineering Contradiction:
Improvestrength against igniter pressureVSAvoidweight of injector
Core Design Contradiction:
StrengthVSWeight of moving object

Solution Approach 1:

Instead of using solid metal throughout the entire injector body, the metal reinforcing member is strategically placed only in specific locations where strength is most needed - namely where the igniter is mounted and where pressure loads are concentrated. The resin member constitutes the majority of the body structure, providing sufficient strength where needed while keeping overall weight low for good user operability.

Inventive Principle:
Principle #3Local quality

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 design maintains sufficient strength and safety while reducing the size and weight of the injector, preserving user operability and lowering manufacturing costs.

Implementation Method 1

an igniter that is provided to the injector body, and configured to discharge, into a combustion chamber in the injector body, ejection energy for ejecting the injection substance through combustion of an ignition charge

Methodology Applied
Scientific EffectCombustion: Combustion

Data Source

PatentEP4173657B1Needleless injector
Publication Date: 2025.11.12 DAICEL CORP
  • EP4173657B1 patent drawingFigure 1
  • EP4173657B1 patent drawingFigure 2A
  • EP4173657B1 patent drawingFigure 2B

AI summary

A needleless injector that ejects an injection substance to a target region without using an injection needle, the needleless injector includes: an injector body formed by a resin member; an igniter; a housing part in which the injection substance is accommodated; and a piston that is configured to be moved by ejection energy in a predetermined path, communicating with the combustion chamber, to pressurize the injection substance. A reinforcing member is provided inside the injector body, formed by a metal member to be a tubular member, and extends in an axial direction of the injector body while surrounding at least the igniter and the combustion chamber, the reinforcing member being disposed to be sandwiched between parts of the injector body in a radial direction of the injector body. With this configuration, sufficient strength of a needleless injector having an igniter as a pressurization source against pressure produced by the igniter can be guaranteed, and the user operability can be prevented from being compromised.