DPF Regeneration Control via Engine Speed and Injection Strategy
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Solution Overview
Problem
Existing exhaust gas purification systems face challenges in efficiently regenerating Diesel Particulate Filters (DPF) during low-speed and low-load operations, leading to filter clogging and increased exhaust pressure, while also suffering from decreased fuel efficiency and noise generation when increasing engine speed for regeneration control.
Innovation Solution
A method for controlling the exhaust gas purification system that adjusts engine speed and fuel injection strategies, including multi-injection and post-injection, to optimize exhaust gas temperature rise during regeneration, with specific engine speed objectives and temperature thresholds to maintain efficient regeneration while minimizing fuel consumption and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If engine speed is increased during regeneration control, then exhaust gas temperature rises and DPF regeneration is promoted, but fuel consumption increases and noise is generated
Solution Approach 1:
The system performs preliminary detection of DPF clogging state using differential pressure sensors and calculates PM accumulation amount before regeneration is needed. This allows the system to plan and execute regeneration at optimal times (when vehicle is stopped or in stable operation), avoiding emergency high-speed regeneration that would consume excessive fuel and generate noise.
Solution Approach 2:
The control system dynamically adjusts engine speed to different target values based on real-time conditions: during active regeneration it sets a first target engine speed, during temperature maintenance it sets a second target speed, and during normal operation it returns to third target speed. This dynamic adjustment optimizes the balance between regeneration effectiveness and fuel consumption.
2Temperature
If multiple injection is performed to raise exhaust gas temperature, then catalyst activation temperature is reached, but fuel amount burned without generating torque increases
Solution Approach 1:
The fuel injection process is segmented into multiple stages: main injection for torque generation, and post-injection for raising exhaust temperature. By dividing the injection timing and purpose, the system achieves both torque generation and temperature rise without requiring all fuel to be burned without torque contribution.
Solution Approach 2:
The system changes injection parameters (timing, duration, amount) based on operational state. During regeneration, post-injection is used to raise temperature; during normal operation, injection timing is optimized for torque generation. This parameter optimization reduces the trade-off between temperature rise and torque loss.
3Temperature
If post-injection is performed to increase HC for oxidation, then exhaust gas temperature rises through HC oxidation, but oil dilution occurs
Solution Approach 1:
The control system continuously monitors exhaust gas temperature and PM accumulation amount, using this feedback to determine when post-injection should be applied. By controlling post-injection duration and timing based on real-time feedback, the system achieves necessary temperature rise for regeneration while minimizing excessive fuel injection that would cause oil dilution.
4Ease of operation
If manual regeneration control is implemented, then regeneration is performed when vehicle is stopped, but operation complexity increases and requires driver intervention
Solution Approach 1:
The system automatically detects DPF clogging state, calculates PM accumulation, determines optimal regeneration timing, and executes the regeneration process without driver intervention. The control unit autonomously manages the entire regeneration sequence, including adjusting engine speed and injection parameters, making the system self-service and eliminating the need for manual operation.
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 regeneration of DPFs with improved temperature rise efficiency, reduced fuel consumption, and minimized noise by optimizing engine speed adjustments and fuel injection techniques, preventing deterioration of fuel efficiency and noise generation during regeneration control.
Implementation Method 1
the HC is oxidized by the oxidation catalyst. By this oxidation, the temperature of the exhaust gas on the downstream of the oxidation catalyst device can be raised
Implementation Method 2
when an exhaust gas temperature is approximately 350° C. or above, the PM collected by the filter is continuously burned and purified
Implementation Method 3
The multiple injection is a delayed multiple-stage injection in which the fuel is injected into the cylinder in many stages. By this multiple injection, a fuel amount simply burned in the cylinder without generating torque is increased, and the temperature of the exhaust gas exhausted from the cylinder can be raised
Data Source
AI summary
In regeneration control, when the catalyst temperature index temperature (Tg2) using the temperature of the oxidation catalyst (12a) as an index is below a predetermined first determination temperature (Tc1), the engine speed of idling is brought to a predetermined first target engine speed (Nei1) which is higher than the engine speed of idling (Nei0) in the ordinary operation, and, further, multi-injection is carried out. On the other hand, when the catalyst temperature index temperature (Tg2) is the predetermined first determination temperature (Tc1) or above, the engine speed of idling is brought to a predetermined second target engine speed (Nei2), which is lower than the predetermined first target engine speed (Nei1) and is higher than the engine speed of idling (Nei0) in ordinary operation, and, further, post injection is carried out, followed by raising of the temperature of an exhaust gas flown into a DPF apparatus (12b) to a predetermined second determination temperature (Tc2). According to the above constitution, in the regeneration control of the DPF apparatus (12b) in an internal combustion engine (10), the regeneration can be forcibly carried out with high efficiency while enhancing the temperature rise efficiency of the exhaust gas, and, at the same time, excessive rise in the exhaust temperature, a deterioration in fuel consumption, and the occurrence of noise are suppressed.