Writing Implement Sealing Mechanism for Axial-Rod Alignment

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Solution Overview

Problem

The assembly of sealing mechanisms in writing instruments is difficult due to misalignment of the lid and barrel components, making it challenging to insert the axial rod correctly.

Innovation Solution

A writing instrument design featuring a lid member that rotates around a rotational axis, guided by a guide portion, with specific surfaces and structures that facilitate easy assembly by ensuring precise alignment during the assembly process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the lid is fixed to the barrel during assembly, then the sealing mechanism can be assembled, but misalignment between the lid and barrel makes it difficult to insert the axial rod

Engineering Contradiction:
ImproveAssembly easeVSAvoidPositional alignment precision
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The guide portion is provided on the barrel before assembly to preliminarily position and align the lid member. This guide structure pre-establishes the correct relative position between the lid and barrel, enabling easy insertion of the axial rod without requiring high assembly precision from the operator.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The guide portion acts as an intermediary element between the lid member and the barrel. It mediates the alignment process by providing a physical reference surface that guides the lid into the correct position, thereby solving the misalignment problem during assembly.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Device complexity

If the lid member structure is simplified, then assembly becomes easier, but the sealing function may be compromised

Engineering Contradiction:
ImproveLid member structure complexityVSAvoidSealing reliability
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The lid member is segmented into functional portions: a closing portion for sealing and a leg portion for structural support and positioning. This segmentation allows each part to perform its specific function efficiently while keeping the overall structure simple and easy to assemble.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP4644132A1Writing implement
Publication Date: 2025.11.05 PILOT PEN CO LTD
  • EP4644132A1 patent drawingFigure 1
  • EP4644132A1 patent drawingFigure 2
  • EP4644132A1 patent drawingFigure 3

AI summary

A writing instrument (10) includes a barrel (20) having an opening (22a); a writing member having a pen tip (13); an advancing and retracting mechanism (40) that advances and retracts the pen tip (13) from the opening (22a); and a sealing mechanism (70) that seals a housing space (S) of the pen tip (13) in a retracted state of the pen tip (13), the sealing mechanism (70) having a lid member (71) that rotates around a rotational axis (79) to close and open the opening (22a) and a guide portion (80) that guides the lid member (71), the lid member (71) having a closing portion (72) having a closing surface (73) that closes the opening (22a) and a first side surface (74), and a leg portion (76) that supports the closing portion (72), the guide portion (80) having a first guide surface (82) that faces the first side surface (74) when the lid member (71) closes the opening (22a), and does not face the first side surface (74) when the lid member (71) opens the opening (22a).