Hybrid DPF Protection via Engine Decoupling and Stoichiometric Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Diesel particulate filters (DPFs) in internal combustion engines face unintentional soot combustion and high temperatures, leading to structural and chemical degradation, especially in lean burn engines where stoichiometric combustion is not feasible over a wide range of operating states.
Innovation Solution
Implementing a method in hybrid vehicles to decouple the combustion engine from the wheel drive train during regeneration, allowing the vehicle to be propelled by an electric motor, and maintaining stable stoichiometric combustion to reduce oxygen concentrations and prevent soot combustion, while also using advanced ignition timing and retarding fuel injection to manage exhaust temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the DPF is regenerated to remove soot buildup, then exhaust gas backpressure is reduced and engine power is improved, but the temperature rises to a point that compromises the structural and chemical integrity of the DPF
Solution Approach 1:
The control system detects early signs of unintentional soot combustion (temperature rise, oxygen concentration changes) and applies countermeasures before the DPF temperature reaches degradation levels. By reducing oxygen concentration in the exhaust gas entering the DPF through stoichiometric combustion control, the system prevents the exothermal reaction from escalating, thereby protecting the DPF structure while still allowing regeneration to proceed
Solution Approach 2:
The system changes the oxygen concentration parameter in the exhaust gas by operating the engine at stoichiometric combustion conditions (lambda ≈ 1) rather than lean burn conditions. This parameter change reduces the oxygen available for soot combustion in the DPF, thereby controlling the combustion rate and preventing excessive temperature rise while still enabling soot removal
2Temperature
If the oxygen concentration in exhaust gas is reduced to prevent soot combustion, then DPF temperature is controlled, but engine operation is restricted to stoichiometric conditions which limits the range of operating states
Solution Approach 1:
The system dynamically adjusts the oxygen concentration control strategy based on real-time detection of DPF conditions. When unintentional combustion is detected, the system temporarily operates at stoichiometric conditions to reduce oxygen concentration and control temperature. When conditions are normal, the system can return to lean burn operation for diesel engines or other operating modes, thereby maintaining adaptability across different operating states while providing temperature control when needed
Solution Approach 2:
The control system continuously monitors exhaust gas parameters (temperature, oxygen concentration) and adjusts the air-to-fuel ratio accordingly. This feedback mechanism allows the system to maintain stoichiometric combustion only when DPF temperature control is required, while permitting lean burn or other operating modes when the DPF is operating within safe temperature ranges, thus preserving engine versatility
3Temperature
If the internal combustion engine is switched off completely to stop exhaust gas flow through the DPF, then soot combustion is prevented, but vehicle propulsion is interrupted and fuel is wasted
Solution Approach 1:
The system extracts and addresses the root cause of excessive temperature (uncontrolled soot combustion) by reducing oxygen concentration in the exhaust gas through stoichiometric combustion control, rather than removing the entire exhaust gas flow by shutting off the engine. This allows the engine to continue running and providing propulsion while the oxygen reduction prevents harmful combustion reactions in the DPF
Solution Approach 2:
The control system acts as an intermediary between the engine operation and DPF temperature control. By adjusting the air-to-fuel ratio to achieve stoichiometric combustion, the control system mediates between the need for continuous engine operation (for propulsion) and the need to control DPF temperature (by reducing oxygen available for combustion). This intermediary control allows both objectives to be achieved simultaneously
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 protects the DPF from unintentional combustion and degradation by maintaining low oxygen concentrations and controlled temperatures, reducing fuel consumption, and allowing for extended operation in filter protection mode without compromising engine performance.
Implementation Method 1
the exothermal heat generated in regeneration may raise the temperature of the DPF
Implementation Method 2
coupling the engine to an alternator generating power for a motor battery
Data Source
AI summary
The invention relates to a method for protecting a DPF in the exhaust section of an internal combustion engine of a motor vehicle from unintentional combustion of soot in the DPF. According to the invention, the motor vehicle is a hybrid vehicle having at least one electric machine and is able to be driven exclusively by one or more electric machine(s) for some time. The vehicle is operated in a DPF protection mode if the system detects that unintentional combustion of soot is taking place or threatening to take place in the DPF, initiating an automatic decoupling of the combustion engine from the wheel drive train, forward propulsion demands by the driver are met exclusively with the aid of the one or more electric machine(s), and the combustion engine is switched off completely or is operated with stable stoichiometric combustion.