Mn-Cr Steel Piston Ring for High Compression Engine Heat Management
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Solution Overview
Problem
Piston rings for high compression ratio automobile gasoline engines struggle to maintain a stable gas seal and heat transfer function, leading to difficulties in combustion near the top dead center and increased nitrogen oxide and soot production.
Innovation Solution
A highly heat conductive piston ring made from Mn—Cr steel with specific compositions of C, Si, Mn, Cr, P, S, Al, Ni, and Cu, combined with hard film coatings and surface treatments, to enhance heat transfer and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If compression ratio is increased to improve fuel efficiency and thermal efficiency, then output and torque increase, but combustion chamber temperature increases causing premature ignition and knocking
Solution Approach 1:
The patent applies parameter changes by optimizing the chemical composition parameters of the piston ring material (carbon 0.20-0.90%, silicon 0.10-0.60%, manganese 0.20-1.50%, chromium 0.30-2.00%) and heat treatment parameters (quenching temperature 800-950°C, tempering temperature 150-500°C) to achieve the desired balance between power output and temperature control
Solution Approach 2:
The patent uses composite materials by creating a multi-element alloy steel composition combining carbon, silicon, manganese, and chromium in specific proportions, which provides both the strength needed for high compression ratio engines and the heat transfer properties to control combustion chamber temperature
2Temperature
If piston crown surface temperature is decreased to achieve proper combustion timing, then heat transfer function improves, but gas seal function may deteriorate
Solution Approach 1:
The patent optimizes material composition parameters (particularly carbon 0.20-0.90% and silicon 0.10-0.60%) to achieve a balance where the piston ring maintains adequate temperature for heat transfer while preserving the hardness and elasticity needed for gas sealing
Solution Approach 2:
The multi-element alloy composition creates a material with balanced properties where carbon provides hardness for sealing, silicon improves heat transfer and oxidation resistance, manganese enhances strength, and chromium improves wear and corrosion resistance, collectively achieving both heat transfer and gas seal functions
3Temperature
If heat transfer function is improved to decrease combustion chamber temperature, then knocking is prevented, but material durability under high temperature may decrease
Solution Approach 1:
The patent optimizes the carbon content (0.20-0.90%) to balance heat transfer capability with material strength, and uses controlled heat treatment parameters (quenching 800-950°C, tempering 150-500°C) to achieve a microstructure that provides both thermal conductivity and durability
Solution Approach 2:
The alloy combines elements with complementary properties: carbon for strength and heat transfer, silicon for oxidation resistance at high temperature, manganese for hardenability and strength, and chromium for high-temperature wear and corrosion resistance, creating a material that maintains durability while improving heat transfer
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 piston ring effectively transfers heat to the cylinder bore, reduces combustion chamber temperature, prevents knocking, and improves heat fatigue resistance, ensuring stable gas seal and heat transfer functions over time.
Implementation Method 1
improving a heat transfer function required in a piston ring mounted to the piston, whereby a combustion heat received by the piston is efficiently transmitted to a cylinder
Data Source
AI summary
There is provided a highly heat conductive piston ring for an internal combustion engine capable of exhibiting a gas seal function and a heat transfer function for a long period of time in a stable manner when used in an automobile gasoline engine having a high compression ratio. The highly heat conductive piston ring for an internal combustion engine is a piston ring for an internal combustion engine having an Mn—Cr steel as a base material, the Mn—Cr steel including C in the range of from 0.52 to 0.65 mass %, Si in the range of from 0.15 to 0.35 mass %, Mn in the range of from 0.60 to 1.00 mass %, Cr in the range of from 0.60 to 1.00 mass %, P in the range of 0.04 mass % or less, S in the range of 0.04 mass % or less, a slight amount of components (total content of Al, Ni, and Cu) in the range of from 0.05 to 3.0 mass %, and a remnant being Fe and unavoidable impurities.