Segmented Piston Assembly for Automated Packing Installation

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Solution Overview

Problem

Conventional fluid pressure devices with pistons face challenges in automating the assembly process of packings due to the need for radial expansion, which limits productivity and requires significant material usage in grooving processes.

Innovation Solution

A fluid pressure device with a piston assembly comprising multiple members forming a packing mounting groove, allowing for easier automation and reduced material usage through casting, where the packing can be mounted without increasing its diameter, and incorporating a combination of members such as a first piston member, a second piston member, a wear ring, and a magnet to define the groove.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a packing mounting groove is formed by grooving (cutting), then the packing can be mounted in the groove, but the packing needs to be pulled radially outward for an increase in diameter during assembly, making automation difficult and reducing productivity

Engineering Contradiction:

Improveease of packing assemblyVSAvoidproductivity

Core Design Contradiction:

Ease of manufactureVSProductivity

Solution Approach 1:

The piston body is divided into multiple members (first piston member, second piston member, fixing plate) that are assembled separately and then combined. The packing mounting groove is formed by the combination of these members rather than being cut into a single piece, allowing the packing to be attached without radial expansion and enabling automated assembly

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Instead of cutting a groove into a solid piston body and then trying to insert the packing, the invention inverts the approach by forming the groove through the assembly of multiple members. The groove is created by the interface between members (e.g., outer circumferential surface of second piston member, inner circumferential surface of fixing plate, and end surface of wear ring), allowing the packing to be simply placed into the groove without complex deformation operations

Inventive Principle:

Principle #13The other way round (Inversion)

2Ease of manufacture

If a packing mounting groove is formed by grooving (cutting), then the groove can accommodate the packing, but significant material is removed during the grooving process, increasing material consumption

Engineering Contradiction:

Improveease of groove formationVSAvoidmaterial consumption

Core Design Contradiction:

Ease of manufactureVSLoss of substance

Solution Approach 1:

The piston body is segmented into multiple members that are assembled to form the complete structure. The packing mounting groove is created by the interface between these members rather than by removing material from a solid block, significantly reducing material consumption

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Multiple members (first piston member, second piston member, wear ring, fixing plate) are combined to form the piston body. The packing mounting groove is formed by the combination of their surfaces, eliminating the need for material removal and reducing waste

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS11280409B2Method for producing piston assembly and hydraulic fluid device

Publication Date: 2022.03.22 SMC CORP

AI summary

A hydraulic fluid cylinder is equipped with a cylinder tube, a piston unit, and a piston rod. The piston unit has a gasket and a piston body comprising a plurality of members and provided with a gasket-mounting groove. The piston body has a first piston member which projects to the outside from the piston rod, and also has a second piston member positioned so as to be adjacent to the first piston member. The gasket-mounting groove is formed from a combination of at least two members.