Post Injection Control for DOC Temperature During Exhaust Brake
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Solution Overview
Problem
During exhaust brake operation in diesel engines, the rapid decrease in intake air volume leads to a rapid temperature rise of the diesel oxidation catalyst (DOC), potentially causing damage or reducing engine performance.
Innovation Solution
A post injection control method that determines whether predetermined regeneration conditions for the diesel particulate filter are met, and if so, performs post-injection with a predetermined amount of fuel to control the temperature, using a system that includes a vehicle operation detector, an exhaust brake operation unit, a diesel oxidation catalyst, a diesel particulate filter, and a controller to manage the injector's operation based on vehicle operation signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If exhaust brake operation is performed, then engine braking force is improved, but intake air volume decreases rapidly causing DOC temperature to rise rapidly
Solution Approach 1:
The controller performs post-injection of fuel before the harmful temperature rise occurs. By detecting exhaust brake operation conditions and proactively injecting fuel to generate heat, the system prevents the DOC temperature from rising to dangerous levels, rather than reacting after the temperature already increased.
Solution Approach 2:
The controller changes the fuel injection parameter by controlling the injector to perform post-injection with a predetermined amount of fuel. This parameter change (adding fuel) directly affects the combustion temperature and allows the system to counteract the temperature rise caused by exhaust brake operation.
2Temperature
If post-injection is performed during exhaust brake operation, then DOC temperature control is improved, but fuel consumption increases
Solution Approach 1:
The controller performs post-injection with a predetermined amount of fuel, which is a controlled partial action rather than full injection. This partial post-injection is sufficient to control the DOC temperature during exhaust brake operation without excessively increasing overall fuel consumption.
Solution Approach 2:
The controller determines whether exhaust brake operation conditions are met by detecting vehicle operation signals, and only performs post-injection when necessary. This feedback-based control ensures fuel is injected only when temperature control is needed, avoiding unnecessary fuel consumption during normal operation.
3Reliability
If regeneration is performed, then DPF cleaning is improved, but DOC temperature may rise rapidly during exhaust brake operation
Solution Approach 1:
The controller detects regeneration conditions and exhaust brake operation conditions beforehand. When both conditions are present, the controller proactively controls post-injection to prevent temperature rise during the regeneration process, rather than allowing temperature to increase and then attempting to control it.
Solution Approach 2:
The controller acts as an intermediary between the regeneration process and the temperature control system. It coordinates the regeneration operation with post-injection control, mediating between the need for DPF cleaning and the need to maintain safe DOC temperatures during exhaust brake 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
Prevents sudden temperature increases in the after-treatment device, thereby preventing damage and maintaining engine performance by controlling the post-injection amount based on target and actual temperatures and engine RPM during exhaust brake operation.
Implementation Method 1
controlling, by the controller, the operation of the injector to perform post-injection with a predetermined amount of fuel when the exhaust brake operation condition is met during the regeneration
Data Source
AI summary
A system includes a vehicle operation detector, an exhaust brake operation unit, a diesel oxidation catalyst, a diesel particulate filter, an injector, and a controller for controlling the operation of the injector and the exhaust brake operation unit. A post injection control method during exhaust brake operation for the system includes: determining whether a predetermined regeneration condition of the diesel particulate filter according to the output signals of the vehicle operation detector is satisfied; performing, by the controller, regeneration by controlling the operation of the injector if the regeneration condition is satisfied; determining, by the controller, whether an exhaust brake operation condition is satisfied during regeneration based on the output signals of the vehicle operation detector; and controlling, by the controller, the operation of the injector to perform post-injection with a predetermined amount of fuel when the exhaust brake operation condition is met during the regeneration.