Direct Alcohol Injection Combustion Mode Engine
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Solution Overview
Problem
Internal combustion engines face limitations in achieving high fuel efficiency and reduced NOx production due to the incompatibility between higher compression ratios preferred for HCCI operation and lower compression ratios required for SI operation, which also leads to control issues during transitions and knock mitigation, necessitating significant hardware adjustments and increased costs.
Innovation Solution
The method involves operating engines using homogeneous charge compression ignition during one condition and spark ignition during another, with varying amounts of alcohol in both modes to control operation, particularly through direct injection to suppress knock and enable higher compression ratios, thereby expanding the HCCI design range and improving fuel economy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If higher compression ratio is used for HCCI operation, then fuel efficiency and NOx reduction are improved, but knock occurs during SI operation limiting the compression ratio
Solution Approach 1:
The patent changes the chemical composition parameter of the fuel by introducing alcohol (ethanol) with high octane rating and high heat of vaporization. This parameter change allows the engine to operate at higher compression ratios without knock during SI mode, while maintaining the benefits of high compression ratio for HCCI mode. The alcohol's properties fundamentally alter the combustion characteristics to enable higher compression ratios.
Solution Approach 2:
Alcohol acts as an intermediary substance that mediates between the conflicting requirements of HCCI and SI combustion modes. By injecting alcohol directly into the cylinder, it provides knock suppression during SI operation through evaporative cooling and high octane rating, thereby enabling the engine to maintain higher compression ratios that benefit both combustion modes.
2Adaptability or versatility
If variable compression ratio hardware is added to accommodate both HCCI and SI requirements, then combustion mode flexibility is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces the mechanical solution of variable compression ratio hardware with a chemical solution using alcohol injection. Instead of mechanically adjusting the compression ratio to accommodate different combustion modes, the invention uses alcohol's chemical properties (high octane rating and evaporative cooling) to enable high compression ratio operation in both HCCI and SI modes, thereby eliminating the need for complex variable compression ratio mechanisms.
Solution Approach 2:
The invention changes the fuel composition parameter rather than the mechanical compression ratio parameter. By using alcohol with specific chemical properties, the system achieves adaptability across combustion modes without modifying the mechanical compression ratio hardware, thus maintaining device simplicity while improving versatility.
3Object-affected harmful factors
If spark retard is used to mitigate engine knock, then knock is reduced, but fuel efficiency decreases
Solution Approach 1:
The patent changes the fuel's octane rating parameter by using alcohol instead of conventional gasoline. This parameter change allows the engine to advance spark timing (improving fuel efficiency) without experiencing knock, because alcohol's high octane rating (113 research octane number) provides superior knock resistance compared to conventional fuels.
Solution Approach 2:
Alcohol serves as an intermediary that enables earlier spark timing by providing knock suppression. The alcohol injection acts as a mediator between the spark ignition system and the air-fuel mixture, allowing the spark to occur earlier in the compression stroke without causing knock, thereby improving fuel efficiency.
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 approach allows for higher compression ratio operation without knock limitations, enhancing HCCI design range and spark ignition fuel economy, while also controlling HCCI combustion timing for improved transient performance, resulting in increased efficiency and reduced emissions.
Implementation Method 1
the large amount of knock suppression that results from evaporative cooling of the fuel/air charge
Implementation Method 2
a substantial amount of heat and pressure may be needed to produce combustion
Data Source
AI summary
A method of operating an engine, comprising of performing homogeneous charge compression ignition combustion during a first operating condition, and performing spark ignition combustion during a second operating condition, where an amount of directly injected alcohol in at least one of said homogeneous charge compression ignition combustion and said spark ignition combustion is varied in response to at least an operating parameter.