Diesel Engine Control Device for Smooth Combustion Mode Switching
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Solution Overview
Problem
Diesel engines face challenges in smoothly switching between premixed combustion and diffuse combustion, leading to combustion noise and torque fluctuations due to limitations in operating conditions and improper control of fuel injection and EGR ratios.
Innovation Solution
A diesel engine control device that manages fuel injection quantity and timing by implementing two control modes: normal injection mode and premixed injection mode, with target values set for each mode, and using EGR devices to adjust the EGR ratio, inlet air quantity, and common rail pressure, allowing gradual changes between modes to prevent sudden changes in combustion parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If premixed combustion is implemented, then NOx emissions and smoke generation are reduced, but the combustion can only be implemented under limited operating conditions (low load region)
Solution Approach 1:
The system dynamically switches between premixed combustion mode and diffuse combustion mode based on operating conditions. The ECU determines the appropriate combustion mode according to engine load and other parameters, allowing the system to adapt to different operating regions while maintaining emission benefits where applicable.
Solution Approach 2:
The system changes key combustion parameters (injection timing, injection quantity, EGR ratio) to transition between combustion modes. By adjusting these parameters, the engine can operate in premixed mode for low load (reducing NOx) and switch to diffuse mode for high load (expanding operating versatility).
2Adaptability or versatility
If switching between premixed combustion and diffuse combustion is not properly carried out, then combustion noise and torque fluctuations are generated
Solution Approach 1:
The ECU performs preliminary determination of the target combustion mode based on predicted operating conditions. By anticipating the need for mode switching and preparing the appropriate control parameters in advance, the system prevents abrupt transitions that would cause combustion noise and torque fluctuations.
Solution Approach 2:
The system uses feedback control to monitor actual combustion characteristics and adjust control parameters during mode transitions. This ensures smooth switching between premixed and diffuse combustion modes, preventing harmful combustion noise and torque fluctuations.
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
Enables smooth switching between premixed and diffuse combustion, reducing combustion noise and torque fluctuations, and improving exhaust gas characteristics by controlling ignition timing and oxygen concentration.
Implementation Method 1
an EGR device that implements EGR to recirculate a part of the exhaust gas to the gas inlet side
Implementation Method 2
controls the injection quantity and injection timing of fuel injected into the cylinder
Implementation Method 3
the injected fuel ignites near compression top dead center and combustion is carried out
Data Source
AI summary
A control device is provided that controls the injection quantity and injection timing of fuel injected into the cylinder of a diesel engine, in which are provided two control modes of: a normal injection mode in which the injection quantity and injection timing are controlled so that the injected fuel ignites near compression top dead center during an injection period; and a premixed injection mode in which the injection quantity and injection timing are controlled so that fuel injection is completed before compression top dead center and the injected fuel ignites near compression top dead center after a premixing period, and target values of control parameters (pilot injection timing, and the like) are set in advance separately for each control mode, the control device comprising change means for gradually changing target values V1 of one control mode into the target values V2 of the other control mode when switching from one control mode to the other control mode.