Exhaust Gas Temperature Control via Dual-Mode Post-Injection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Exhaust gas treatment apparatus modules, such as diesel oxidation catalyst and selective catalytic reduction modules, do not operate effectively at low temperatures, necessitating temperature increases to enhance operation and efficiency, including the removal of deposits like soot and urea buildup, which existing methods like post-injection struggle to manage efficiently.
Innovation Solution
A method involving two modes of fuel injection into engine cylinders, with the first mode injecting fuel at a higher rate for longer durations to achieve a higher target temperature (T1) for oxygen-based regeneration and the second mode injecting at a lower rate for shorter durations to achieve a lower target temperature (T2) for NO2-based regeneration, utilizing the existing fuel injector and exhaust gas recirculation path to optimize temperature control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If post-injection is used to increase exhaust gas temperature, then temperature of exhaust gas is increased, but the method cannot efficiently manage different temperature requirements for different regeneration processes
Solution Approach 1:
The system dynamically switches between two distinct fuel injection modes (first mode with higher injection rate for T1, and second mode with lower injection rate for T2) based on the required regeneration process. This dynamic adaptation allows the system to meet different temperature requirements efficiently, resolving the contradiction between achieving high temperature and maintaining control flexibility.
Solution Approach 2:
The invention changes the fuel injection parameters (injection rate, injection duration, timing) to achieve different target temperatures. By adjusting these parameters between two defined modes, the system can efficiently reach either T1 for oxygen-based regeneration or T2 for NO2-based regeneration, thereby resolving the limitation of single-mode post-injection.
2Temperature
If fuel injection rate is increased to reach higher target temperature T1, then oxygen-based regeneration is enabled, but the injection duration and fuel consumption increase
Solution Approach 1:
The system applies partial action by selectively using the first injection mode (higher fuel rate) only when oxygen-based regeneration at T1 is required, and uses the second mode (lower fuel rate) for NO2-based regeneration at T2. This partial application of high fuel injection avoids unnecessary fuel consumption while still enabling the higher temperature process when needed.
Solution Approach 2:
The fuel injection process is segmented into two distinct modes with different characteristics. The first mode uses higher injection rate for longer duration to achieve T1, while the second mode uses lower injection rate for shorter duration to achieve T2. This segmentation allows optimal fuel consumption for each specific regeneration type.
3Measurement precision
If the exhaust gas recirculation valve is closed during first mode, then temperature control precision is improved, but the system complexity and control difficulty increase
Solution Approach 1:
The control system performs preliminary actions by pre-defining two injection modes with specific parameters (injection rates, durations, timing) and associated valve states. This preliminary configuration simplifies the control logic, as the ECU only needs to select between pre-programmed modes rather than dynamically calculate optimal parameters, thereby reducing control complexity while maintaining 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
This method effectively raises exhaust gas temperatures to optimal levels for both oxygen-based and NO2-based regeneration processes, improving the efficiency and reliability of the exhaust gas treatment apparatus while minimizing user noticeability and ensuring compliance with emission regulations.
Implementation Method 1
injecting fuel from the fuel injector into each of the one or more combustion cylinders in a main injection event to initiate a primary combustion event that drives the piston
Implementation Method 2
periodically injecting fuel at a first rate of injection from the fuel injector into one of the one or more combustion cylinders in a first mode subsidiary injection event after the main injection event during a period in which the fuel injected in the first mode subsidiary injection event passes into the first module without combusting in the combustion unit for raising temperature of exhaust gas in the exhaust gas treatment apparatus by combustion therein
Implementation Method 3
an exhaust gas recirculation path between the exhaust conduit and upstream of the intake valve, the exhaust gas recirculation path having an exhaust gas recirculation valve to open and close the exhaust gas recirculation path
Implementation Method 4
it is known to use the diesel oxidation catalyst module to increase the temperature of the exhaust gas passing through it
Implementation Method 5
This may be achieved by introducing unburnt fuel upstream of the diesel oxidation catalyst for oxidation in the diesel oxidation catalyst thereby to increase the temperature of the exhaust gas leaving the diesel oxidation catalyst module
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A method of controlling operation of an engine. The engine comprises a combustion unit, an exhaust gas recirculation path between the exhaust conduit and upstream of the intake valve, the exhaust gas recirculation path having an exhaust gas recirculation valve. The engine further comprises an exhaust gas treatment apparatus configured to receive fluid from the exhaust conduit and comprising a first module and a second module downstream of the first module. The method comprises a first mode for increasing a temperature of exhaust gas in the exhaust gas treatment apparatus to a first temperature, T1, and a second mode for increasing temperature of exhaust gas in the exhaust gas treatment apparatus to a second temperature, T2, wherein T1, > T2. The method comprises, in both the first and second modes, injecting fuel from the fuel injector into each of the one or more combustion cylinders in a main injection event to initiate a primary combustion event that drives the piston. The first mode has a first mode duration, the first mode comprising: closing the exhaust gas recirculation valve; and periodically injecting fuel at a first rate of injection from the fuel injector into one of the one or more combustion cylinders in a first mode subsidiary injection event after the main injection event during a period in which the fuel injected in the first mode subsidiary injection event passes into the first module without combusting in the combustion unit for raising temperature of exhaust gas in the exhaust gas treatment apparatus by combustion therein, wherein a delay is invoked after execution of the first mode before a subsequent execution of the first mode, the delay having a delay duration of at least 50 times the first mode duration. The second mode has a second mode duration shorter than the first mode duration, the second mode comprising: periodically injecting fuel at a second rate of injection, wherein the second rate of injection is lower than the first rate of injection, from the fuel injector into one of the one or more combustion cylinders in a second mode subsidiary injection event after the main injection event during a period in which the fuel injected in the second mode subsidiary injection event passes into the first module without combusting in the combustion unit for raising temperature of exhaust gas in the exhaust gas treatment apparatus by combustion therein. The method comprises invoking the first mode when targeting the first temperature, T1, and invoking the second mode when targeting the second temperature, T2