Fuel Injection Control System for Smoke and Cooling Loss Reduction
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Solution Overview
Problem
Existing control systems for internal combustion engines fail to achieve a fuel injection pattern of initial high and later low rates, which is necessary to suppress smoke generation and minimize cooling losses during combustion.
Innovation Solution
A control system that includes an electronic control unit to manage fuel injection rates by reducing pressure in the control chamber of fuel injection valves, allowing for a predetermined pressure difference to open injection holes and subsequently reducing the reference pressure to lower the fuel injection rate during the later stage of fuel injection, using a pressure increasing device to maintain high initial injection rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the fuel injection rate is low in the initial stage of fuel injection, then the smoke generation in the cylinder is reduced, but the combustion efficiency deteriorates and smoke increases
Solution Approach 1:
The fuel injection is divided into multiple stages with different injection rates. The ECU controls the fuel injection valve to provide a high injection rate in the initial stage (main injection) followed by a low injection rate in the later stage (post-injection), creating a periodic variation in injection rate that optimizes both combustion efficiency and smoke reduction
2Loss of energy
If the fuel injection rate is high in the later stage of fuel injection, then the fuel spray diffuses excessively and cooling loss increases, but the combustion completeness is improved
Solution Approach 1:
The fuel injection rate is varied periodically throughout the injection process. After the initial high-rate injection, the ECU reduces the injection rate in the post-injection phase by controlling the needle lift duration, thereby minimizing fuel spray diffusion and cooling losses while still achieving complete combustion through the staged approach
3Quantity of substance
If the needle lift duration is extended to increase fuel injection rate, then the fuel injection quantity increases, but the injection pressure decreases due to common rail pressure drop
Solution Approach 1:
The ECU performs preliminary control by managing the needle lift duration and timing before the actual fuel injection occurs. By precisely controlling when the needle lifts and how long it remains open, the system optimizes fuel injection quantity while maintaining injection pressure through coordinated control of the fuel injection valve and common rail pressure
4Device complexity
If the fuel injection valve structure is simplified, then the device complexity is reduced, but the control precision of fuel injection rate is deteriorated
Solution Approach 1:
The system replaces complex mechanical control mechanisms with an electronic control system. The ECU electronically controls the fuel injection valve's needle lift timing and duration, achieving precise fuel injection rate control through electronic signals rather than complex mechanical linkages, thereby reducing overall device complexity while maintaining high control precision
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 system effectively suppresses smoke generation in the initial stage of fuel injection and minimizes cooling losses in the later stage by precisely controlling fuel injection rates, achieving the desired pattern of initial high and later low injection rates.
Implementation Method 1
a high-pressure pump configured to increase a pressure of the fuel and feed the fuel under pressure
Implementation Method 2
reduce a pressure of the fuel in the control chamber to be lower than a pressure of the fuel in the fuel passage connected to the control chamber... move the needle in a direction to open the injection holes by reducing the pressure of the fuel such that a first pressure difference as a pressure difference between the pressure of the fuel in the control chamber and the pressure of the fuel in the fuel passage connected to the control chamber is equal to or larger than a predetermined pressure difference
Implementation Method 3
Each of the plurality of fuel injection valves is configured to directly inject a fuel into a corresponding one of the cylinders by moving a needle and opening injection holes
Data Source
AI summary
An internal combustion engine includes a plurality of cylinders, a plurality of fuel injection valves, a control chamber provided in each of the fuel injection valves. A control system for the internal combustion engine includes an electronic control unit which is configured to (i) reduce a pressure of the fuel in the control chamber to be lower than a pressure of the fuel in the fuel passage connected to the control chamber, in each of the fuel injection valves, (ii) reduce the pressure of the fuel such that a first pressure difference is equal to or larger than a predetermined pressure difference, so as to move the needle in a direction to open the injection holes, and (iii) reduce the reference pressure by reducing the pressure of the fuel in a second injection valve, such that the first pressure difference after operation is smaller than the predetermined pressure difference.