Particulate Filter Temperature Control via Exhaust Oxygen Management
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Solution Overview
Problem
Particulate filters in diesel engines can overheat during regeneration events when the accelerator pedal is tipped out, leading to potential damage due to increased oxygen concentration and runaway combustion, which can cause thermal damage to the filter and surrounding components.
Innovation Solution
A system and method that uses active temperature control by operating an electric machine in generator mode to charge the battery and supply fuel to the engine to reduce oxygen concentration in the exhaust gas, thereby preventing overheating during regeneration events, especially when an accelerator pedal tip-out occurs. This involves monitoring temperature and soot loading to predict and mitigate potential overheating conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If fuel is cut-off during accelerator pedal tip-out to save fuel during deceleration, then fuel economy is improved, but Oxygen concentration in exhaust gas increases causing runaway combustion in the particulate filter
Solution Approach 1:
The system applies preliminary anti-action by detecting the tip-out condition and initiating a compensating fuel injection before runaway combustion can occur. The ECU calculates the required compensating fuel amount based on the difference between requested and actual engine torque, and injects this fuel into the combustion chamber to reduce oxygen concentration in the exhaust gas before it reaches the particulate filter, thereby preventing the harmful effect of runaway combustion.
2Temperature
If compensating fuel is supplied to reduce oxygen concentration in exhaust gas, then particulate filter temperature is controlled, but additional fuel consumption occurs
Solution Approach 1:
The system applies parameter changes by dynamically adjusting the compensating fuel injection amount based on real-time operating conditions. The ECU continuously monitors engine torque, vehicle speed, and tip-out duration to calculate the optimal compensating fuel quantity, thereby controlling particulate filter temperature while minimizing additional fuel consumption. The compensating fuel amount is precisely controlled to achieve temperature management without excessive fuel usage.
3Loss of energy
If electric machine operates in generator mode to charge battery, then electrical energy is stored, but additional load is applied to the engine
Solution Approach 1:
The system applies feedback by continuously monitoring the engine's actual torque output and comparing it with the requested torque. When the electric machine operates in generator mode and creates additional load, the ECU detects the torque deficit through this feedback mechanism and automatically calculates the required compensating fuel injection to make up the difference, thereby maintaining the desired engine performance while allowing electrical energy storage to proceed.
4Reliability
If accelerator pedal tip-out is detected to trigger active temperature control, then particulate filter overheating is prevented, but system complexity increases
Solution Approach 1:
The system applies universality by utilizing existing engine components and control systems to achieve multiple functions. The ECU that already manages fuel injection and ignition is extended to also handle tip-out detection and compensating fuel calculation. The fuel injection system, already present for combustion, is used dual-purpose to both maintain engine operation and control exhaust gas oxygen concentration. This multi-functionality approach prevents particulate filter overheating without requiring entirely new dedicated systems.
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
Effectively reduces the risk of overheating in particulate filters during regeneration events, preventing damage and maintaining the integrity of the filter and surrounding components by actively managing oxygen concentration and torque output.
Implementation Method 1
operating an electric machine drivingly connected to the engine in a generator mode to charge a battery of the motor vehicle
Implementation Method 2
supplying fuel to the engine to generate torque to compensate for the additional load applied to the engine by the electric machine
Data Source
AI summary
A vehicle and method reduce heating of a particulate filter during a regeneration event in response to an accelerator pedal tip-out and particulate filter temperature exceeding or anticipated to exceed a threshold by fueling the engine to reduce oxygen in the exhaust flowing to the particulate filter. An electric machine may be operated as a generator charging a battery to compensate or offset torque produced by the fueling of the engine. The current or anticipated particulate filter temperature may be estimated by a soot combustion model for a current regeneration event and/or a future regeneration event based on soot loading of the particulate filter.