Piston Pin Lightening for Rigidity and Vibration Control

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Solution Overview

Problem

Existing piston pins in engines face challenges in maintaining durability and reliable power transmission while minimizing engine vibrations and ensuring long disturbance-free operation, as they often compromise between mass reduction and structural rigidity.

Innovation Solution

A piston pin design featuring external and internal lightening elements, with a circular cross-sectional projection and slide bearing surfaces, providing an I-beam shape at both ends and symmetrical apertures, ensures even force distribution and reduced mass, enhancing structural rigidity and reliability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Weight of moving object

If the piston pin mass is reduced through lightening, then engine vibrations are minimized and productivity is improved, but the structural rigidity and reliability of power transmission deteriorate

Engineering Contradiction:
Improvepiston pin massVSAvoidstructural rigidity
Core Design Contradiction:
Weight of moving objectVSStrength

Solution Approach 1:

The piston pin is segmented into multiple functional zones: affixing areas at both ends for attaching to the piston, a center area (third affixing area) for attaching to the connecting rod, and lightening areas between these zones. This segmentation allows mass reduction in non-critical areas while preserving structural integrity in load-bearing regions.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different regions of the piston pin are given different structural characteristics: the affixing areas maintain full cross-sectional area for strength, while the lightening areas between them have reduced material. The external lightening creates I-beam shaped ends with material concentrated at the outer edges where bending stresses are highest, while internal apertures remove material from the center where stresses are lower.

Inventive Principle:
Principle #3Local quality

2Weight of moving object

If the piston pin mass is reduced through lightening, then engine vibrations are minimized, but the durability and disturbance-free operation deteriorate

Engineering Contradiction:
Improvepiston pin massVSAvoiddurability
Core Design Contradiction:
Weight of moving objectVSReliability

Solution Approach 1:

The piston pin is segmented into multiple functional zones: affixing areas at both ends for attaching to the piston, a center area (third affixing area) for attaching to the connecting rod, and lightening areas between these zones. This segmentation allows mass reduction in non-critical areas while preserving structural integrity in load-bearing regions.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The design incorporates slide bearing surfaces in the affixing areas that provide cushioning and load distribution before critical failure can occur. These bearing surfaces are positioned to handle the varying forces from gas pressure and inertia, protecting the lightened structure from stress concentrations.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

3Weight of moving object

If the piston pin mass is reduced through lightening, then engine vibrations are minimized, but the power transmission reliability deteriorates

Engineering Contradiction:
Improvepiston pin massVSAvoidpower transmission reliability
Core Design Contradiction:
Weight of moving objectVSReliability

Solution Approach 1:

Different regions of the piston pin are given different structural characteristics: the affixing areas maintain full cross-sectional area for strength, while the lightening areas between them have reduced material. The external lightening creates I-beam shaped ends with material concentrated at the outer edges where bending stresses are highest, while internal apertures remove material from the center where stresses are lower.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The design incorporates slide bearing surfaces in the affixing areas that provide cushioning and load distribution before critical failure can occur. These bearing surfaces are positioned to handle the varying forces from gas pressure and inertia, protecting the lightened structure from stress concentrations.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

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

The design achieves a balance between reduced mass and sufficient structural rigidity, enabling reliable power transmission and minimized engine vibrations, thereby ensuring high operational reliability and extended disturbance-free engine operation.

Implementation Method 1

first and the second affixing areas are provided with slide bearing surfaces... the forces are divided as evenly as possible to the piston pin and the connecting rod

Methodology Applied
Scientific EffectForce distribution:

Implementation Method 2

The greater the mass of the reciprocating parts have the stronger the forces are. Thus, by reducing the mass of the moving parts these varying forces may be diminished and also the suppression of the engine vibration may be simplified

Methodology Applied
Scientific EffectMass reduction:

Data Source

PatentEP2409054B1Piston pin and a piston - piston pin combination
Publication Date: 2015.09.09 WARTSILA FINLAND OY
  • EP2409054B1 patent drawingFigure 1~2
  • EP2409054B1 patent drawingFigure 3A~3E
  • EP2409054B1 patent drawing

AI summary

The invention relates to a piston pin (100) for attaching the piston (10) of a piston engine to the connecting rod (30), the piston pin including at its first end (120) and its second end (130) a first and a second affixing area for attaching the piston pin to the piston and between these in the center area (125) a third affixing area for attaching the piston pin (100) to the connecting rod (30), the cross-sectional projection of the piston pin being circular and the piston pin including a lightening portion (150). Said lightening (150) has been provided at both ends (120, 130) of the piston pin in said center area (125) outside a third affixing area. The invention also relates to a combination of a piston and a piston pin.