Exhaust Purification Control for DPF Regeneration During Idling
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Solution Overview
Problem
In vehicles equipped with special equipment, forced regeneration of the diesel particulate filter (DPF) is hindered during long time idling operations when the power take-off (PTO) device is in operation, leading to excessive PM accumulation and increased back pressure, which can cause engine malfunctions and reduced working efficiency.
Innovation Solution
A control method for the exhaust emission purification system that prohibits multistage delay injection during long time idling operations when the PTO device is in operation, instead using post injection to raise exhaust gas temperature and perform forced regeneration, thereby avoiding engine speed variations and ensuring DPF regeneration without PTO operation stoppage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If forced regeneration is performed during long time idling operation when PTO device is in operation, then DPF regeneration is achieved, but engine speed variation occurs due to unstable delay combustion
Solution Approach 1:
The invention changes the combustion parameters by switching from multistage delay injection to post injection based on operating conditions. When PTO device is operating during long time idling, post injection is used to supply HC to the exhaust gas, which burns more stably than delay injection, thereby maintaining engine speed stability while achieving DPF regeneration.
2Temperature
If multistage delay injection control is used to raise exhaust temperature for DPF regeneration, then PM combustion is achieved, but engine speed varies significantly
Solution Approach 1:
The invention changes the injection timing parameter from delay injection to post injection under specific operating conditions (long time idling with PTO operation). This parameter change allows exhaust temperature to be raised for PM combustion while the combustion occurs after main combustion, minimizing impact on engine speed.
3Stability of the object's composition
If forced regeneration is forbidden when PTO device is in operation, then engine speed stability is maintained, but excessive PM accumulation occurs in DPF
Solution Approach 1:
The invention changes the injection strategy parameter from prohibiting forced regeneration to allowing it with post injection control when PTO device is operating during long time idling. This parameter change enables PM removal while maintaining engine speed stability by using post injection which has less impact on combustion stability.
4Stability of the object's composition
If post injection control is used instead of multistage delay injection during long time idling with PTO operation, then engine speed variation is avoided, but exhaust temperature rise efficiency may be reduced
Solution Approach 1:
The invention uses post injection to supply HC (hydrocarbon) to the exhaust gas, which then burns in the exhaust system. While post injection alone may be less efficient than multistage delay injection for temperature rise, it provides sufficient temperature increase for PM combustion while maintaining engine speed stability, representing a partial action that achieves the necessary but not excessive temperature rise.
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 allows for effective DPF regeneration without causing engine speed variations, preventing excessive PM accumulation and back pressure issues, thus maintaining engine efficiency and preventing DPF clogging.
Implementation Method 1
HC (hydrocarbon) supplied in the exhaust gas through post injection and the like is burnt by oxidation catalyst disposed upstream of the DPF or by DPF-supported oxidation catalyst, the oxidation reaction heat of which is utilized to raise the exhaust gas temperature of the DPF entrance
Implementation Method 2
the DPF temperature is raised above the combustion temperature of PM accumulated in the DPF so as to perform combustion removal of the PM
Data Source
Figure 1
Figure 2
AI summary
An exhaust emission purification system (1) comprising a controller (40) performing exhaust temperature rise control executing multistage delay injection control for raising the exhaust temperature, if the exhaust gas temperature (Tg2) is lower than a predetermined judgment temperature (Tc1), and performing PM combustion removal control executing post injection control, if the exhaust gas temperature (Tg2) becomes equal to or higher than the predetermined judgment temperature (Tc1), when forced regeneration of a DPF (12b) is carried out, wherein multistage delay injection control is forbidden when an idle operation state of an internal combustion engine (10) sustains for a predetermined judgment tome (tic) and a PTO device (26) is in operating state. The control method of an exhaust emission purification system and an exhaust emission purification system are thereby provided, which are capable of sustaining a DPF in a good state in a vehicle equipped specially with a DPF for purifying PM in exhaust gas by executing forced regeneration while avoiding variation in engine speed even if the PTO device is in operating state during a long time idling operation.