Engine Control Device for Diesel Particulate Filter Regeneration
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Solution Overview
Problem
Conventional control devices for internal combustion engines face challenges in accurately controlling the temperature of diesel particulate filters during regeneration, due to variations in fuel injection characteristics and the large heat capacity of the filters, leading to potential overheating or insufficient heating.
Innovation Solution
A control device that includes an air-fuel ratio detecting element and a controller to adjust the air-fuel ratio to a target value, ensuring the filter is maintained within an appropriate temperature range for regeneration by supplying fuel according to actual injection characteristics, using feedback control to maintain the desired temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If feedback control is performed according to emission gas temperature detected on downstream side of filter, then temperature control is achieved, but large time lag occurs between emission gas temperature change and filter temperature change causing filter temperature to be set out of appropriate range
Solution Approach 1:
The patent performs preliminary heating of the filter by injecting fuel into the combustion chamber before the regeneration process is fully initiated. This advance action compensates for the inherent time lag in temperature propagation through the filter, ensuring the filter reaches the appropriate temperature range for regeneration without excessive delay.
Solution Approach 2:
The patent introduces an intermediary temperature detection point within the filter structure (between the upstream and downstream sides) to detect temperature changes earlier than the downstream sensor alone could provide. This intermediary measurement allows the control system to anticipate filter temperature changes and adjust fuel injection accordingly, reducing the effective time lag.
2Temperature
If fuel injection is increased to heighten filter temperature for regeneration, then regeneration effectiveness improves, but filter temperature may excessively rise beyond appropriate range
Solution Approach 1:
The patent implements a feedback control system that continuously monitors filter temperature (or proxy temperature measurements) and adjusts fuel injection quantity accordingly. When the filter temperature approaches the upper limit of the appropriate range, the control system automatically reduces fuel injection to prevent excessive temperature rise, maintaining the temperature within the optimal regeneration range.
Solution Approach 2:
The patent dynamically adjusts fuel injection characteristics during the regeneration process based on real-time temperature conditions. The injection quantity and timing are continuously modified to match the current state of the filter, allowing aggressive heating when temperature is low and conservative heating when temperature approaches the upper limit, thus preventing excessive temperature rise.
3Temperature
If fuel injection timing is retarded to heighten exhaust gas temperature, then filter temperature increases, but injection characteristics vary with time and between valves causing quantity shifts
Solution Approach 1:
The patent uses feedback control to compensate for variations in fuel injection characteristics. By monitoring the actual temperature response and comparing it with the target temperature, the system adjusts the fuel injection quantity to account for differences between individual valves and changes over time, ensuring consistent regeneration performance despite injection characteristic variations.
Solution Approach 2:
The patent dynamically changes fuel injection parameters (quantity, timing, duration) based on detected temperature conditions and injection characteristic variations. By adjusting these parameters in real-time, the system compensates for differences between valves and temporal changes, maintaining reliable and consistent filter temperature control for regeneration.
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 solution effectively controls the regeneration temperature of the diesel particulate filter, preventing overheating and ensuring efficient particulate matter burning, even when actual fuel injection characteristics differ from designed characteristics.
Implementation Method 1
the control device performs a regeneration control to regenerate the filter. More specifically, the control device controls the engine to heighten the temperature of the filter, so that the deposited particulate matters are burned off and removed from the filter
Implementation Method 2
an engine additionally performs a fuel injection (i.e., post injection of fuel) according to a regeneration control at a timing, which is sufficiently retarded from a timing of the compression top dead center, to burn fuel of the post injection in an exhaust system
Implementation Method 3
an exhaust gas temperature sensor is disposed between the oxygen catalyst and the filter. The control device performs a feedback control so as to adjust an exhaust gas temperature detected by the sensor to a target exhaust gas temperature
Data Source
AI summary
A control device has a throttle valve and fuel injection valves supplying air and fuel to an internal combustion engine, a meter detecting an actual quantity of the air supplied to the engine, a sensor detecting an actual oxygen concentration of an exhaust gas outputted from an exhaust system of the engine, and an ECU controlling the valves. To regenerate an exhaust emission purifier disposed in the exhaust system at a target temperature appropriate to the regeneration of the purifier, the ECU determines a target oxygen concentration corresponding to a target air-fuel ratio and a basic air quantity according to a torque required of the engine and controls the valves according to the actual air quantity and the actual oxygen concentration to supply a basic quantity of fuel and the basic quantity of air to the engine at the target air-fuel ratio.