Common Rail Fuel Injection Control for Low Load Combustion
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Solution Overview
Problem
In diesel engines with common rail type fuel injection devices, prior injections can lead to defective ignition and combustion when the engine is operating at low load states, resulting in excessive carbon monoxide emissions and white smoke, particularly at high idle rotating speeds.
Innovation Solution
The engine device employs a common rail type fuel injection system that omits prior injections when the engine is in a low load state or when the main clutch is in a power disconnection state, using detection means to determine the load and clutch state to adjust injection strategies, thereby reducing the risk of defective ignition and combustion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If prior injection is executed in low load state, then NOx and noise reduction is achieved, but defective ignition and combustion occur, causing excessive CO and white smoke
Solution Approach 1:
The fuel injection control system dynamically adjusts the injection strategy based on real-time detection of engine load state. The control unit switches between executing prior injection (when load is high) and omitting prior injection (when load is low), making the system adaptive to varying operating conditions to prevent defective combustion while maintaining emissions control benefits
Solution Approach 2:
The system changes the operational parameter of prior injection execution based on load state detection. By detecting whether the engine is in low load state and accordingly determining to execute or omit prior injection, the system optimizes combustion reliability and prevents CO emissions under different loading conditions
2Productivity
If prior injection is executed at high idle rotating speed, then combustion is promoted, but white smoke is significantly generated
Solution Approach 1:
The control system dynamically responds to the specific operating condition of high idle rotating speed by detecting this state and omitting prior injection accordingly. This dynamic adjustment prevents the generation of white smoke from unburned fuel while maintaining appropriate combustion promotion through main injection alone
Solution Approach 2:
The system converts the potentially harmful effect of prior injection (which causes white smoke at high idle) into a beneficial control decision by detecting the high idle condition and omitting prior injection, thereby eliminating the harmful white smoke emission while preserving combustion effectiveness through alternative control strategies
3Ease of operation
If main clutch is in power disconnection state, then power transmission is interrupted, but prior injection causes defective combustion
Solution Approach 1:
The control unit takes preliminary action by detecting the power disconnection state of the main clutch before the combustion cycle completes, and accordingly omits prior injection in advance. This preliminary detection and response prevents defective combustion from occurring during the power disconnection period
Solution Approach 2:
The system uses feedback from the clutch state detection to adjust the fuel injection strategy. By continuously monitoring whether the main clutch is connected or disconnected and adjusting prior injection execution accordingly, the system ensures combustion reliability matches the power transmission state
Data Source
AI summary
A problem exists that in the case that a prior injection (a pilot injection B or a previous injection C) before a main injection A is executed when an engine is driven at a low load, a defective ignition and a defective combustion tend to be caused, an amount of carbon monoxide (CO) in an exhaust gas becomes excessive, and the carbon monoxide is discharged as white smoke. An engine device is mounted to a working vehicle, and a common rail type fuel injection device which injects fuel to the engine at multiple stages during one combustion cycle. The common rail type fuel injection device does not execute the prior injections B and C coming before the main injection A in the case that a load applied to the engine is in a low load state in which a load is lower than that at a working time by the working vehicle.