Thermally Stratified Combustion for Low Cetane Fuel
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Solution Overview
Problem
Heavy work vehicles typically use diesel engines that generate undesirable emissions, and existing spark ignited engines are not suitable for heavy work applications, especially when using low cetane fuels like ethanol.
Innovation Solution
A compression ignition engine with thermally stratified layers of gas within combustion chambers, facilitated by an internal exhaust gas recirculation (EGR) arrangement, is used to ignite and combust low cetane fuels effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a diesel engine is used in heavy work vehicles, then higher torque and pull-down characteristics are achieved, but undesirable emissions are generated
Solution Approach 1:
The patent changes the combustion parameters by creating thermally stratified layers within the combustion chamber, allowing compression ignition of low cetane fuels while maintaining diesel-like torque characteristics and reducing emissions through controlled thermal gradients
2Object-generated harmful factors
If a spark ignited engine is used to reduce emissions, then greenhouse gas emissions are reduced, but the engine is not suitable for heavy work applications
Solution Approach 1:
The patent changes the ignition mechanism from spark ignition to compression ignition with thermally stratified layers, enabling the engine to achieve both low emissions and high power output suitable for heavy work applications by creating localized high-temperature zones for fuel auto-ignition
3Adaptability or versatility
If ethanol with low cetane value is used as fuel, then renewable resource utilization is improved, but ignition difficulty increases under certain conditions
Solution Approach 1:
The patent applies local quality by creating thermally stratified layers with different temperature zones within the combustion chamber, providing localized high-temperature regions that enable reliable ignition of low cetane fuels like ethanol while maintaining cooler overall chamber temperatures
Solution Approach 2:
The patent performs preliminary action by pre-heating specific zones within the combustion chamber through controlled exhaust gas recirculation and thermal stratification before fuel injection, ensuring that the fuel encounters sufficient temperature for reliable ignition even under cold start and low load conditions
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
This solution enables the use of low cetane fuels like ethanol in heavy work vehicles, improving ignition and combustion performance across a range of conditions, including cold starts and low load conditions, while reducing emissions.
Implementation Method 1
a compression ignition engine having thermally stratified layers of gas within combustion chambers of the piston-cylinders sets to facilitate ignition
Implementation Method 2
thermally stratified layers of gas within combustion chambers... to facilitate ignition and support operation in a range of conditions
Data Source
AI summary
A power system includes an intake arrangement and a compression ignition engine including piston-cylinder sets. Each piston-cylinder set includes: a cylinder; a piston positioned within the cylinder to form a combustion chamber in between; an intake valve configured to open and close the intake port; an exhaust valve configured to open and close the exhaust port; and a fuel injector. During an exhaust stroke, the exhaust valve is opened to enable exhaust gas to flow out; during an initial portion of an intake stroke, the intake valve is opened to enable the intake air to flow into the combustion chamber, and during a further portion of the intake stroke, the intake valve is closed and the exhaust valve is opened to enable a portion of the exhaust gas to flow back into the combustion chamber in order to create thermally stratified layers of intake gas and exhaust gas.