Cylinder Cover and Stop Ring Assembly With Tapered Guide

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Solution Overview

Problem

The assembly of cylinder devices is difficult due to the need to insert a rod guide into a cylinder while reducing the diameter of a stopper ring using a jig, leading to high assembly complexity.

Innovation Solution

A cylinder device design featuring a first tapered portion in the opening portion and a second tapered portion on the cover portion, allowing the stop ring to be guided and elastically deformed during assembly, reducing the need for manual diameter reduction with a jig.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the stopper ring is inserted into the cylinder while reducing its diameter using a jig, then the stopper ring can be securely fitted into the cylinder opening, but the assembly process becomes complex and difficult

Engineering Contradiction:
Improvesecure fitting of stopper ringVSAvoidassembly process complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies parameter changes by modifying the geometric parameters of the assembly process. The tapered portion creates a gradual transition in diameter from the cylinder opening to the stopper ring accommodation groove, allowing the stopper ring to be elastically deformed and guided into place without requiring external jigs or complex assembly tools.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent utilizes curvature by implementing a tapered (conical) surface instead of a cylindrical surface. This curved geometry naturally guides the stopper ring during insertion, distributing the deformation force gradually along the tapered surface, which simplifies the assembly process and eliminates the need for complex jigs while ensuring reliable fitting.

Inventive Principle:
Principle #14Spheroidality (Curvature)

2Manufacturing precision

If the stopper ring diameter is reduced using a jig during assembly, then proper engagement is achieved, but manual intervention and specialized tools are required

Engineering Contradiction:
Improveengagement precisionVSAvoidassembly automation capability
Core Design Contradiction:
Manufacturing precisionVSExtent of automation

Solution Approach 1:

The patent implements self-service by designing the tapered portion integrated into the cylinder structure itself. The tapered geometry automatically performs the diameter reduction function during the insertion process, eliminating the need for separate jigs or manual intervention. This self-contained solution enables automation as the stopper ring is guided and deformed into place simply by inserting it into the tapered opening.

Inventive Principle:
Principle #25Self-service

3Ease of operation

If a tapered portion is added to the cylinder opening, then the stop ring can be easily guided and assembled, but the cylinder structure becomes more complex

Engineering Contradiction:
Improveassembly easeVSAvoidcylinder structure complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The patent applies merging by integrating the tapered portion directly into the cylinder opening structure. Rather than adding a separate guiding component or assembly aid, the tapered geometry is combined with the cylinder wall itself, forming a unified structure that provides both the structural function of the cylinder and the guiding function for assembly.

Inventive Principle:
Principle #5Merging (Combining)

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

Facilitates easier assembly by allowing the stop ring to be pressed and guided into place, reducing assembly difficulty and enabling automation, while maintaining design quality and hygiene.

Implementation Method 1

an inner diameter of the first tapered portion at the open end is larger than a mean diameter of the stop ring in a state of not being elastically deformed

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Data Source

PatentEP4641030A1Cylinder device
Publication Date: 2025.10.29 SMC CORP
  • EP4641030A1 patent drawingFigure 1
  • EP4641030A1 patent drawingFigure 2
  • EP4641030A1 patent drawingFigure 3

AI summary

A cylinder device (10) comprises: a cylinder tube (12) having an opening (24) formed therein; a cover section (14) that is columnar and closes the open end (26) of the opening; and a stop ring (16) that has an inner part accommodated in an accommodation groove (32) in the cover section and an outer part engaged with an engagement groove (30) in the opening. A tapered section (28) increasing in diameter toward the open end is formed in the opening. The inner diameter of the tapered section in the open end is larger than the central diameter of the stop ring when not in an elastically deformed state.