Multi-Zone Fuel Injection for Diesel Engine NOx and Efficiency
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Solution Overview
Problem
Current fuel injection devices for diesel engines face challenges in achieving both high thermal efficiency and reduced NOx emissions while maintaining acceptable in-cylinder pressure and fuel injection precision, particularly during constant pressure heating processes.
Innovation Solution
A fuel injection device with a fuel injector and a fuel injection change unit that divides the combustion chamber into multiple zones, allowing for precise control of fuel injection rates and flow channel areas, thereby optimizing in-cylinder pressure and thermal efficiency, and includes a control unit to manage injection patterns to prevent peak pressure exceedance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If external exhaust gas recirculation is used to reduce NOx emissions, then the amount of nitrogen oxide is reduced, but the thermal efficiency is lowered
Solution Approach 1:
The combustion chamber is divided into multiple combustion zones, and fuel injection is controlled separately for each zone. This segmentation allows different regions to have optimized combustion conditions, enabling NOx reduction in certain zones while maintaining thermal efficiency in others.
Solution Approach 2:
Different fuel injection rates and strategies are applied to different combustion zones based on their specific requirements. This local quality approach ensures that each zone receives the appropriate amount of fuel for its function, resolving the contradiction between NOx reduction and thermal efficiency.
2Productivity
If fuel injection amount is increased to promote combustion during constant pressure heating process, then combustion is improved, but the peak in-cylinder pressure exceeds allowable limits
Solution Approach 1:
The fuel injection is divided into multiple stages with different injection rates. The first stage uses a higher injection rate to promote combustion, while the second stage uses a lower injection rate to control peak pressure, allowing both combustion promotion and pressure control.
Solution Approach 2:
Fuel injection is performed in periodic stages rather than continuously. The injection rate varies over time with a first stage at higher rate and a second stage at lower rate, enabling dynamic control of both combustion intensity and peak pressure.
3Ease of operation
If twin needle type fuel injection device is used to control fuel injection amount, then fuel injection control is achieved, but the fuel injection amount is converged to a constant amount
Solution Approach 1:
The fuel injection device transitions from a static constant flow channel area design to a dynamic variable flow channel area design. The flow channel area changes during the injection process to enable variable fuel injection amounts while maintaining ease of operation.
Solution Approach 2:
The fuel injection process is divided into periodic stages with different flow channel areas. The flow channel area varies over time to provide different injection rates for different combustion zones, enabling adaptability while keeping the device operationally simple.
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 solution enables simultaneous reduction of NOx emissions and enhancement of thermal efficiency while maintaining in-cylinder pressure within safe limits, ensuring precise fuel injection and preventing pressure drops during constant pressure heating processes.
Implementation Method 1
a fuel injector that injects fuel into a combustion chamber
Implementation Method 2
pressures on a back side of an inner needle and an outer needle are adjusted to control the fuel injection amount
Implementation Method 3
the fuel injected from a fuel injector is self-injected due to a compression in the combustion chamber
Implementation Method 4
a compression ratio is high as compared with a gasoline engine, and a peak of the in-cylinder pressure in the combustion chamber, which is generated by the combustion of fuel, is increased
Data Source
AI summary
A fuel injection device is used in an internal combustion engine having a combustion chamber partitioned by a cylinder head, a cylinder, and a piston crown surface so that at least one of the amount of NOx, Pmax, and a thermal efficiency η is maintained at a predetermined value. The fuel injection device includes a fuel injection change unit. The fuel injection change unit virtually divides the combustion chamber into N number of combustion zones where N is a natural number of 2 or more, and can change a fuel injection method according to the respective combustion zones. The fuel injection change unit divides the combustion chamber into the N number of combustion zones, thereby being capable of eliminating a difference of heat in the respective combustion zones, and precisely controlling an in-cylinder pressure P in the combustion chamber. As a result, the amount of NOx and the thermal efficiency can be optimized. Therefore, both of a reduction in the amount of NOx and the high thermal efficiency can be achieved.