Cartridge Dispenser Piston Ribbed Protrusion Design

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Solution Overview

Problem

Cartridge-type dispensers for viscous materials face issues with piston disengagement due to variations in molding accuracy, leading to laborious assembly and potential malfunctions during content extrusion, especially when piston diameters are small or large, affecting airtightness and operational smoothness.

Innovation Solution

A cartridge-type dispenser design featuring a piston with a trunk portion having a longitudinal ribbed protrusion for reduced contact area and an hourglass shape, which forms a gap with the main body to prevent disengagement and ensure smooth sliding, while maintaining airtightness and facilitating air discharge.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the piston diameter is increased to improve airtightness, then airtightness is improved, but the piston can be disengaged from the main body due to increased inner pressure and assembly becomes laborious

Engineering Contradiction:
ImproveairtightnessVSAvoidassembly ease
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The piston is divided into multiple functional sections: a front end portion for sealing against the main body, a rear end portion for receiving push-in force, and a trunk portion with ribbed protrusions for guided sliding. This segmentation allows each part to perform its specific function optimally without compromising the others.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different portions of the piston are designed with different characteristics: the front end portion has a sealing surface for airtightness, the rear end portion is flat for force application, and the trunk portion has ribbed protrusions for sliding guidance. This local differentiation resolves the contradiction between airtightness and ease of assembly.

Inventive Principle:
Principle #3Local quality

2Ease of operation

If the piston diameter is decreased to facilitate assembly, then assembly ease is improved, but the piston can be easily disengaged from the main body

Engineering Contradiction:
Improveassembly easeVSAvoidpiston retention
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The piston is divided into multiple functional sections: a front end portion for sealing against the main body, a rear end portion for receiving push-in force, and a trunk portion with ribbed protrusions for guided sliding. This segmentation allows each part to perform its specific function optimally without compromising the others.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Instead of relying solely on piston diameter for retention, the invention adds a longitudinal dimension with ribbed protrusions that engage with the main body interior. This multi-dimensional engagement prevents disengagement while maintaining ease of assembly.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Reliability

If the piston is firmly fitted to the main body to prevent disengagement, then piston retention is improved, but the piston cannot slide smoothly causing operational issues

Engineering Contradiction:
Improvepiston retentionVSAvoidsliding smoothness
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The piston is divided into multiple functional sections: a front end portion for sealing against the main body, a rear end portion for receiving push-in force, and a trunk portion with ribbed protrusions for guided sliding. This segmentation allows each part to perform its specific function optimally without compromising the others.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different portions of the piston are designed with different characteristics: the front end portion has a sealing surface for airtightness, the rear end portion is flat for force application, and the trunk portion has ribbed protrusions for sliding guidance. This local differentiation resolves the contradiction between airtightness and ease of assembly.

Inventive Principle:
Principle #3Local quality

Data Source

PatentEP2578181B1Cartridge-type dispenser
Publication Date: 2016.08.10 YOSHINO KOGYOSHO CO LTD
  • EP2578181B1 patent drawingFigure 1A~1B
  • EP2578181B1 patent drawingFigure 2~3
  • EP2578181B1 patent drawingFigure 4~5

AI summary

Provided is a cartridge-type dispenser suitable for extruding viscous materials, wherein a piston does not fall easily out of a cartridge main body and yet is capable of extruding the contents with a smooth action. The cartridge-type dispenser is provided with a cartridge main body (1) that has a filling space (M) for the contents and is equipped with an extrusion nozzle (1a) on the front end thereof, and a piston (2) that is slidably disposed in the filling space (M) of the cartridge main body (1) and extrudes the contents of the filling space (M) from an end of the extrusion nozzle (1a) by application of a push-in force. The piston (2) is configured from a trunk portion (2a) that has an outer circumferential wall that runs along an inner wall of the cartridge main body (1) and is disposed inside the inner circumferential wall of the main body with a gap therebetween, a front end wall portion (2b) that is provided on one end of the trunk portion (2a) and directly contacts the contents of the filling space (M), and a rear end wall portion (2c) that is provided on the other end of the trunk portion (2a) whereon the rod of a push-in tool is pressed to apply the push-in force on the piston (2) itself. On the outer circumferential wall of the trunk portion (2a), protrusions (3) are provided, which contact the inner circumferential wall of the cartridge main body (1). The points of contact form sliding parts of the piston (2) but do not seal the interior of the cartridge main body (1).