Cast Iron Piston Asymmetric Windows Weight Noise
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Solution Overview
Problem
Internal combustion engine pistons face challenges in reducing production costs, friction, and noise emissions while maintaining load-bearing capabilities.
Innovation Solution
A cast iron-based piston with asymmetric windows in the side walls carrying the piston pin boss, optimized for stress distribution, featuring a one-piece design, cooling channels, and reduced skirt wall contact areas, which enhances weight reduction, resilience, and friction minimization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a cast steel piston with recesses is used, then production costs can be reduced, but weight reduction and noise emission reduction are limited
Solution Approach 1:
The patent applies asymmetry by providing windows in the side walls that are asymmetric relative to one another at least on the side of the skirt walls. This asymmetric window configuration enables greater weight reduction compared to symmetric designs while maintaining structural integrity and load-bearing capabilities during engine operation.
Solution Approach 2:
The patent segments the solid piston structure by introducing windows (openings or through-holes) in the side walls carrying the piston pin boss. This segmentation reduces material usage and piston weight while the closed piston pin boss maintains structural strength. The segmentation approach allows cost-effective cast steel construction with reduced weight.
2Weight of moving object
If windows are added to reduce weight, then noise emissions increase due to reduced skirt resilience
Solution Approach 1:
The asymmetric window configuration strategically places material removal in specific regions while preserving skirt wall integrity in critical areas. This asymmetric design reduces overall weight but maintains sufficient skirt resilience to dampen impulses transmitted to the cylinder bore, thereby controlling noise emissions.
Solution Approach 2:
The patent applies local quality by differentiating the window configuration between pressure side and counter-pressure side, and by ensuring the piston pin boss remains closed (without discontinuities) to maintain local structural strength. This localized material distribution optimizes the balance between weight reduction and noise control.
3Weight of moving object
If asymmetric windows are used to reduce weight and noise, then manufacturing complexity increases
Solution Approach 1:
The patent employs cast steel construction with integrated asymmetric windows that are formed directly during the casting process. The casting method inherently handles the complex asymmetric geometry without requiring additional machining steps, allowing the piston to be self-sufficient in achieving its optimized shape while keeping manufacturing processes relatively simple and cost-effective.
4Strength
If the piston pin boss is kept closed to maintain strength, then weight reduction opportunities are limited
Solution Approach 1:
The patent applies local quality by keeping the piston pin boss closed (without discontinuities) to maintain local structural strength where it is most needed for pin support, while simultaneously introducing asymmetric windows in the side walls for overall weight reduction. This localized structural reinforcement allows weight reduction in non-critical areas while maintaining strength in load-bearing regions.
Data Source
AI summary
A cast piston for an internal combustion engine is made of an iron-based material and has windows in at least one side wall carrying a piston pin boss. The windows are asymmetric relative to one another on the side of the skirt walls.