Multi-Diameter Hammer Piston Structure for Galling Reduction

Solution Overview

Problem

The pistons in hydraulic hammers used in work machines face issues such as galling, damage due to high surface contact pressure, erosion from high-velocity hydraulic fluid, and clogging of grooves, leading to reduced performance and shorter piston life.

Innovation Solution

A piston design for hydraulic hammer assemblies featuring a first portion with a first diameter, a second portion with a larger diameter and a plurality of grooves, and a third portion with a smaller diameter, which reduces contact pressure and enhances hydraulic fluid flow, thereby minimizing galling and erosion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If the piston has a uniform diameter design, then the structure is simple, but the contact pressure on mating parts increases leading to galling and damage

Engineering Contradiction:

Improvepiston structureVSAvoidresistance to galling and damage

Core Design Contradiction:

Device complexityVSStrength

Solution Approach 1:

The piston is divided into multiple sections with different diameters (first section with first diameter, second section with second diameter, third section with third diameter). This segmentation allows each section to have optimized contact characteristics with mating parts, reducing galling and damage while maintaining structural functionality.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different sections of the piston have different diameters tailored to their specific functional requirements. The first section has a smaller diameter for certain hydraulic passages, the second section has a larger diameter to reduce contact pressure on the cylinder wall, and the third section has a reduced diameter for the tool strike interface, optimizing local stress distribution.

Inventive Principle:

Principle #3Local quality

2Quantity of substance

If grooves are provided on the piston to connect hydraulic passages, then fluid flow is enabled, but the grooves become clogged or obstructed reducing flow and increasing pressure

Engineering Contradiction:

Improvehydraulic fluid flowVSAvoidgroove clogging resistance

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The groove dimensions are specifically optimized with controlled depth and width parameters. The grooves are machined to precise specifications that balance fluid flow requirements with resistance to clogging, ensuring reliable hydraulic passage connection throughout piston operation.

Inventive Principle:

Principle #35Parameter changes

3Strength

If the piston diameter is increased to reduce contact pressure, then galling is reduced, but the hydraulic fluid flow and pressure distribution is affected

Engineering Contradiction:

Improveresistance to gallingVSAvoidhydraulic fluid flow

Core Design Contradiction:

StrengthVSQuantity of substance

Solution Approach 1:

The piston is divided into multiple sections with different diameters (first section with first diameter, second section with second diameter, third section with third diameter). This segmentation allows each section to have optimized contact characteristics with mating parts, reducing galling and damage while maintaining structural functionality.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different sections of the piston have different diameters tailored to their specific functional requirements. The first section has a smaller diameter for certain hydraulic passages, the second section has a larger diameter to reduce contact pressure on the cylinder wall, and the third section has a reduced diameter for the tool strike interface, optimizing local stress distribution.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS12296453B2Hammer piston

Publication Date: 2025.05.13 CATERPILLAR INC

AI summary

A piston for a hydraulic hammer of a work machine is disclosed. The piston comprises a first portion having a first diameter, a second portion having a second diameter larger than the first diameter, the second portion having a plurality of grooves, and a third portion having a third diameter less than the second diameter.