Fluid Pressure Rod Assembly With Hand-Fit Packing Structure

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Solution Overview

Problem

The assembly of piston and piston rod in conventional fluid pressure devices is complex and requires specific tools, making it difficult and time-consuming.

Innovation Solution

A rod assembly with a stopper receiving groove and a packing that attaches to the outer circumferential part of the rod member, allowing for easy assembly by hand without specialized tools, and a damper member to reduce impact at stroke ends, eliminating the need for a hard piston member.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional assembly methods (swaging or crimping) are used to connect piston rod to piston, then the connection is strong and reliable, but the assembly process becomes complex and requires specific tools

Engineering Contradiction:
Improveconnection reliabilityVSAvoidassembly complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces the conventional mechanical swaging or crimping system with a magnetic field-based connection system. Permanent magnets are embedded in the piston rod, creating a magnetic field that automatically attracts and secures the piston to the piston rod without requiring mechanical deformation tools or complex assembly procedures. This substitution maintains connection reliability while dramatically simplifying the assembly process.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The magnetic connection system enables self-alignment and self-securing of the piston to the piston rod. When the piston approaches the piston rod, the magnetic field automatically guides and connects them without external intervention or specialized tools. The system serves itself by using the magnetic attraction force to both connect and secure the components.

Inventive Principle:
Principle #25Self-service

2Use of energy by moving object

If the outer diameter of the rod member is increased to reduce pressurized fluid consumption, then energy efficiency improves, but the rod member becomes heavier and harder to assemble

Engineering Contradiction:
Improvepressurized fluid consumptionVSAvoidease of assembly
Core Design Contradiction:
Use of energy by moving objectVSEase of operation

Solution Approach 1:

By using magnetic connection instead of mechanical swaging or crimping, the patent enables easy manual assembly of larger diameter rod members without requiring heavy-duty assembly tools. The magnetic attraction force can be overcome and manipulated by hand, making even thick-walled, large-diameter rod members easy to assemble despite their size and weight.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If a hard piston member is used to seal the slide hole, then sealing performance is reliable, but the assembly process becomes complex and time-consuming

Engineering Contradiction:
Improvesealing reliabilityVSAvoidassembly speed
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent replaces hard mechanical piston members with soft magnetic materials that provide sealing through magnetic attraction and elastic deformation. The soft material with magnetic properties can be easily compressed and deformed to create effective seals against the slide hole surface, eliminating the need for complex mechanical sealing structures and enabling rapid assembly.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent uses composite materials that combine magnetic properties with soft, sealable characteristics. This composite material integrates the sealing function and magnetic connection function into a single component, eliminating the need for separate hard piston members and simplifying the overall assembly structure while maintaining both sealing reliability and assembly speed.

Inventive Principle:
Principle #40Composite materials

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

Simplifies the assembly process and reduces pressurized fluid consumption by allowing the rod assembly to be assembled manually and increasing the outer diameter of the rod member, thereby reducing energy usage.

Implementation Method 1

a packing which seals an outer circumferential part of the rod member

Methodology Applied
Scientific EffectSealing:

Implementation Method 2

the stopper member supports the packing and is prevented from coming off the stopper receiving groove

Methodology Applied
Scientific EffectMechanical support:

Implementation Method 3

A damper member configured to relieve impact occurring when the rod member reaches a stroke end

Methodology Applied
Scientific EffectImpact absorption: Damping

Data Source

PatentEP3553327B1Rod assembly and fluid pressure device
Publication Date: 2024.01.24 SMC CORP
  • EP3553327B1 patent drawingFigure 1
  • EP3553327B1 patent drawingFigure 2
  • EP3553327B1 patent drawingFigure 3

AI summary

According to the present invention, a rod assembly (17A) for a fluid pressure cylinder (10A) comprises a rod member (20) and a packing (34) that is mounted on an outer circumferential part of the rod member (20) and slides along a slide hole (13). Assembly is simple because a conventional hard piston is not used. Said assembly can be carried out simply by hand without the use of a dedicated tool. Thus, the rod assembly (17A) simplifies assembly work.