Fuel Injection Control Apparatus for Diesel Combustion Optimization
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Solution Overview
Problem
Fuel injection systems for premixed compression ignition diesel engines face challenges in maintaining low HC generation and high fuel efficiency, particularly at varying engine loads, where narrow cone angle fuel injection valves can lead to decreased air utilization and soot generation at high loads, and deteriorated combustibility at low loads.
Innovation Solution
A fuel injection control apparatus that divides fuel injection into pre-injection and post-injection phases, with the pre-injection further divided into multiple smaller injections, optimizing the injection cone angle and timing to ensure efficient fuel distribution within the combustion chamber, reducing adherence to chamber walls and improving combustion quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a fuel injection valve with a narrow cone angle is used, then early injection fuel is supplied effectively to the combustion chamber, but air utilization decreases at high loads leading to increased soot generation
Solution Approach 1:
The fuel injection system dynamically adjusts the injection cone angle based on engine operating conditions. At low loads, a narrow cone angle (120° or less) is used for precise fuel delivery, while at high loads, the cone angle is widened to improve air utilization and reduce soot generation. This dynamic adjustment resolves the contradiction between injection precision and soot control.
Solution Approach 2:
The injection cone angle parameter is changed according to engine load conditions. By varying this geometric parameter, the system achieves optimal fuel distribution at different operating points, preventing both imprecise injection at low loads and soot formation at high loads.
2Manufacturing precision
If early injection fuel is divided into multiple portions at low loads, then atomization and intermixing improve, but combustibility deteriorates leading to reduced fuel efficiency
Solution Approach 1:
The injection strategy dynamically changes based on engine load. At low loads, fuel is injected as a single portion or fewer portions to maintain combustibility, while at high loads, the fuel is divided into multiple portions for better atomization and mixing. This dynamic approach resolves the contradiction between mixture uniformity and fuel efficiency.
Solution Approach 2:
The number of injection portions is changed according to engine operating conditions. By adjusting this parameter, the system achieves optimal balance between air-fuel mixing quality and combustion efficiency across different load ranges.
3Manufacturing precision
If fuel is injected in multiple portions, then atomization improves, but the complexity of injection control increases
Solution Approach 1:
The fuel injection process is segmented into multiple portions only when necessary (at high loads), while at low loads, a simpler single-portion injection is used. This conditional segmentation reduces overall system complexity while maintaining high atomization quality when needed.
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 achieves premixed compression ignition combustion with reduced HC generation and enhanced fuel efficiency by ensuring uniform air-fuel mixing and minimizing fuel adherence, thereby preventing rapid combustion and improving combustibility across different engine loads.
Implementation Method 1
the amount of the fuel injected in each injection decreases, which is advantageous in terms of atomization and intermixing with air
Implementation Method 2
a compression stroke for compressing the sucked air begins... the air-fuel mixture is compressed by piston 6 such that the pressure and temperature of the air-fuel mixture increase
Implementation Method 3
When the temperature of the air-fuel mixture increases, the fuel auto-ignites, and as a result, combustion occurs in cylinder 3
Data Source
Figure 1
Figure 2A~2C
Figure 3
AI summary
In a compression stroke, fuel injection valve 2 injects a single portion of the fuel immediately after -28° ATDC. Immediately after this injection, a second portion of the fuel is injected as close as possible to the first injection without overlapping. The amount of the fuel injected in the second injection takes a value obtained by subtracting the amount of the fuel injected in the first injection from the amount of the fuel required to obtain a required torque, and this amount is larger than the amount of the fuel injected in the first injection. Next, fuel injection valve 2 injects a single portion of the fuel immediately after -18° ATDC. The amount of the fuel injected at this time is approximately double the amount of the fuel injected in the first injection at -28° ATDC timing and smaller than the amount of the fuel injected in the second injection.