Internal Combustion Engine Piston Skirt With Gradual Thickness

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Solution Overview

Problem

Internal combustion engine pistons face high frictional forces due to uneven rigidity and contact pressure between skirts and the cylinder wall, which can lead to increased wear and reduced efficiency, while also requiring weight reduction.

Innovation Solution

The design incorporates arc-shaped thrust and anti-thrust skirts with connecting sections that have gradually increasing thickness and curvature, along with aprons and projections to distribute stress uniformly and reduce friction, ensuring consistent rigidity and contact pressure across the piston.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If stress dispersing portions are implemented as projections extending outwardly from the lower end portion of the skirt, then the rigidity of the lower end portion of the skirt is enhanced locally, but the rigidity of the entire skirt becomes uneven causing locally high contact pressure and large frictional force

Engineering Contradiction:

Improverigidity of lower end portion of skirtVSAvoidfrictional force between skirt and cylinder wall

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The patent applies local quality by providing stress dispersing portions only at specific locations where stress concentration occurs (connecting sections between skirts and aprons), rather than uniformly throughout the entire skirt. This localized reinforcement maintains uniform overall rigidity while addressing specific weak points, preventing both local deformation and excessive friction.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The skirt is segmented into multiple regions with different thickness characteristics. The stress dispersing portions are positioned specifically at the connecting sections between skirts and aprons, creating a segmented structure that distributes stress evenly across different zones rather than concentrating it in one area.

Inventive Principle:

Principle #1Segmentation

2Weight of moving object

If the piston design aims for weight reduction, then the overall mass of the piston decreases, but the structural integrity and rigidity may be compromised

Engineering Contradiction:

Improveweight of pistonVSAvoidrigidity of skirt

Core Design Contradiction:

Weight of moving objectVSStrength

Solution Approach 1:

The patent uses local quality by making the stress dispersing portions thinner than the main skirt body. This allows weight reduction in non-critical areas while maintaining adequate thickness in the skirt for overall structural integrity, achieving a balance between weight reduction and rigidity requirements.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The piston employs a composite structural design where the skirt and stress dispersing portions have different thickness characteristics, creating a composite structure that optimizes both weight and strength. The varying thickness profile allows the design to meet both weight reduction and rigidity requirements simultaneously.

Inventive Principle:

Principle #40Composite materials

Data Source

PatentUS8701619B2Internal combustion engine piston

Publication Date: 2014.04.22 ASTEMO LTD

AI summary

An internal combustion engine piston includes a piston crown, a thrust-side skirt, an anti-thrust-side skirt, a first apron, and a second apron. The first and second aprons are connected to the thrust-side and anti-thrust-side skirts through connecting sections. Each connecting section has a thickness that gradually increases as followed from a proximal longitudinal end to a distal longitudinal end, wherein the proximal longitudinal end is closer to the piston crown, and the distal longitudinal end is closer to a distal longitudinal end of a corresponding one of the thrust-side and anti-thrust-side skirts.