Transient Torque Substitution for Diesel Emission Control
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Solution Overview
Problem
Modern diesel engines face a conflict between reducing nitrogen oxide emissions and maintaining drivability due to the delayed charge pressure buildup caused by air system inertia during rapid load changes, leading to increased NOx emissions and compromised drivability.
Innovation Solution
A method that reduces the short-term load point of the internal combustion engine during transient phases, with simultaneous torque substitution by an electric machine or ancillary unit, using a dynamic indicator to detect transient states and calculate a transient correction factor for optimal EGR rates, thereby reducing NOx emissions without compromising drivability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the driver command torque is increased during rapid load changes, then drivability is improved, but nitrogen oxide emissions increase due to delayed charge pressure buildup
Solution Approach 1:
The electric machine acts as an intermediary between the driver's torque demand and the ICE. During transient phases, the electric machine provides supplementary torque to meet the driver's demand, allowing the ICE to operate at reduced load with optimized EGR rates, thereby maintaining drivability while reducing NOx emissions.
Solution Approach 2:
The control system detectively identifies transient states in advance using the dynamic indicator and pre-adjusts the torque allocation to the electric machine. This preliminary action ensures that the ICE is not overloaded during transient phases, preventing excessive NOx formation while still meeting the driver's torque requirements.
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 effectively reduces nitrogen oxide emissions and maintains driver command torque, improving both emission and driving performance by allowing higher EGR rates and minimizing torque limitations, thus alleviating the conflict between emissions and drivability.
Implementation Method 1
a torque is substituted by a transient torque applied by the electric machine
Implementation Method 2
The oxygen content in the cylinder is reduced by exhaust gas recirculation and a reduction of the temperature in the combustion chamber results as a consequence thereof
Implementation Method 3
a delayed buildup of the charge pressure due to the inertia of the air system in a diesel engine
Data Source
AI summary
A method for reducing exhaust gas emissions during a transient transitional phase of a vehicle including an internal combustion engine and an electric machine or an alternative ancillary unit, the method including, in the transient transitional phase, over a period of time defined by a dynamic indicator for determining the transient transitional phase, a correction intervention is carried out by a load point reduction of the internal combustion engine and, simultaneously thereto, a torque substitution by a transient torque applied by the electric machine or the alternative ancillary unit.