Injector Plunger Stopper Elastic Locking Mechanism

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Solution Overview

Problem

Existing injectors face challenges in housing a seal body into a barrel without damage and preventing the plunger from falling off from the barrel.

Innovation Solution

The injector design includes a cylindrical barrel with a discharge port, a seal body that comes into close contact with the barrel's inner surface, a plunger for moving the seal body, and stoppers that are elastically contacted with the barrel or plunger to prevent separation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a convex portion is added to the barrel inner circumferential surface to prevent plunger removal, then plunger security is improved, but the seal body may be damaged during housing

Engineering Contradiction:
Improveplunger securityVSAvoidseal body damage
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

A stopper is introduced as an intermediary component between the barrel and plunger to prevent plunger removal. The stopper includes a stopper protrusion that engages with a stopper groove, providing a reliable locking mechanism without requiring direct contact between the seal body and the barrel's convex portion, thus preventing seal body damage while maintaining plunger security.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The plunger prevention mechanism is segmented into separate components: the stopper protrusion on the plunger and the stopper groove on the barrel. This segmentation allows the sealing function and the locking function to be independent, enabling the seal body to be housed without damage while the plunger remains securely locked through the stopper engagement.

Inventive Principle:
Principle #1Segmentation

2Ease of manufacture

If the seal body is housed into the barrel, then the injector is assembled, but the seal body may climb over the convex portion and get damaged

Engineering Contradiction:
Improveassembly processVSAvoidseal body damage
Core Design Contradiction:
Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The stopper acts as a mediator that prevents direct interaction between the seal body and the convex portion during assembly. The stopper protrusion and stopper groove engagement provides a guided path for the plunger, ensuring the seal body is housed smoothly without climbing over harmful convex structures.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The stopper structure is pre-configured on both the barrel and plunger before assembly. The stopper groove is formed on the barrel inner circumferential surface and the stopper protrusion is formed on the plunger, creating a predetermined engagement path that guides the seal body into the barrel without damage during the housing process.

Inventive Principle:
Principle #10Preliminary action

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

This design allows the seal body to be housed without damage and prevents the plunger from falling off, ensuring reliable operation and user safety.

Implementation Method 1

a stopper disposed on one of the barrel and the plunger and coming into elastic contact with the other in a radial direction of the barrel

Methodology Applied
Scientific EffectElastic contact: Elasticity

Data Source

PatentEP3586894B1injector
Publication Date: 2025.04.30 SHOFU INC
  • EP3586894B1 patent drawingFigure 1
  • EP3586894B1 patent drawingFigure 2
  • EP3586894B1 patent drawingFigure 3

AI summary

PROBLEM TO BE SOLVED: To house a seal body into a barrel without damage and to prevent a plunger from falling off from the barrel in an injector. SOLUTION: An injector 10 comprises a cylindrical barrel 12 including a discharge port 12c, a seal body 14b coming into close contact with an inner circumferential surface 12e of the barrel 12, a plunger 16 for pushing and moving the seal body 14b to the discharge port side of the barrel 12, and a stopper 16d disposed on one of the barrel 12 and the plunger 16 and coming into elastic contact with the other in a radial direction of the barrel 12.