Direct Injection Engine Fuel Timing for Soot Reduction
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Solution Overview
Problem
Direct injection internal combustion engines experience a high generation of soot when engine temperature is low due to fuel injection during the first half of the intake stroke, leading to increased smoke and unburned gases.
Innovation Solution
Implementing a direct injection internal combustion engine with three fuel injections, where the second injection occurs near the bottom dead center range, and the first and third injections are set on the advance and retard sides of this range, respectively, ensuring fuel injections occur from the second half of the intake stroke to the first half of the compression stroke, with increased angular intervals at higher engine speeds and advancing injection timings as the engine temperature rises.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If fuel injection is performed during the first half of the intake stroke, then the fuel can be supplied in time for combustion, but the generation amount of soot increases when engine temperature is low
Solution Approach 1:
The fuel injection is divided into three separate injections (first, second, and third injections) performed at different timing within the intake stroke. This segmentation allows the fuel to be supplied in multiple stages, improving mixing with intake air and reducing soot generation while ensuring adequate fuel supply for combustion.
Solution Approach 2:
The injection timing parameters are optimized by performing the first injection in the first half of the intake stroke and the second and third injections in the second half of the intake stroke. This parameter change in injection timing distribution improves fuel-air mixing homogeneity and reduces soot generation during cold engine operation.
2Quantity of substance
If three-divided fuel injections are performed with the first injection in the first half of the intake stroke, then fuel supply is ensured, but combustion stability deteriorates due to increased soot generation at low engine temperature
Solution Approach 1:
The fuel injection is divided into three separate injections (first, second, and third injections) performed at different timing within the intake stroke. This segmentation allows the fuel to be supplied in multiple stages, improving mixing with intake air and reducing soot generation while ensuring adequate fuel supply for combustion.
Solution Approach 2:
The injection timing parameters are optimized by performing the first injection in the first half of the intake stroke and the second and third injections in the second half of the intake stroke. This parameter change in injection timing distribution improves fuel-air mixing homogeneity and reduces soot generation during cold engine operation.
3Object-generated harmful factors
If the angular interval between fuel injections is increased at higher engine speeds, then fuel adherence to piston surface is reduced, but the control device operation complexity increases
Solution Approach 1:
The angular intervals between the first and second injections, and between the second and third injections, are dynamically adjusted based on engine rotational speed. At higher engine speeds, the intervals are increased to allow more time for fuel-air mixing and reduce fuel adherence to the piston surface, while the control device adapts to these changes through speed-based control logic.
Data Source
AI summary
A direct injection internal combustion engine has an injector for directly injecting fuel into a combustion chamber. A first fuel injection, a second fuel injection, and a third fuel injection are performed in one combustion cycle of the engine when a temperature of the engine is equal to or lower than a predetermined temperature. The second fuel injection is completed in a near-bottom dead center range of 160 deg. to 200 deg. after the top dead center at which the intake stroke starts, the first fuel injection is performed in a range which is set on the advance side of the near-bottom dead center range, and the third fuel injection is performed in a range which is set on the retard side of the near-bottom dead center range. The first and third fuel injections are completed in a range from 90 deg. to 270 deg. after the top dead center.