Diesel Engine Fuel Retention Estimation for Filter Regeneration
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Solution Overview
Problem
Diesel engines with variable valve timing face challenges in managing residual exhaust gas and retained fuel, leading to increased engine torque and emissions, as well as inefficient particulate filter regeneration due to soot accumulation.
Innovation Solution
An engine control method that estimates the amount of fuel retained in a cylinder from one cycle to the next using oxidation catalyst temperature, allowing for accurate adjustment of fuel injection to improve torque delivery and reduce emissions, without requiring cylinder pressure measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If post fuel injection is used to increase exhaust gas temperature for particulate filter regeneration, then soot combustion is facilitated, but retained fuel in the cylinder increases engine torque and causes earlier combustion timing
Solution Approach 1:
The controller estimates the amount of retained fuel in the cylinder before the next combustion event and uses this information to adjust the pilot fuel injection amount accordingly. This preliminary estimation and adjustment prevents excessive torque and combustion timing issues before they occur.
Solution Approach 2:
The system uses exhaust gas temperature as feedback to estimate retained fuel amounts. The temperature increase from post-injection fuel combustion in the exhaust system provides information about how much fuel was not combusted in the cylinder, which is then used to adjust subsequent fuel injections.
2Productivity
If post fuel injection is used to raise exhaust gas temperatures, then particulate filter regeneration is enhanced, but control of exothermic reactions becomes more complex
Solution Approach 1:
The exhaust gas temperature acts as an intermediary measurement that indirectly provides information about retained fuel amounts. Instead of directly measuring fuel retention or implementing complex multi-parameter control, the system uses the temperature increase in the exhaust system as a proxy to estimate retained fuel and adjust pilot injections accordingly.
3Ease of operation
If traditional fuel injection control is used without retained fuel estimation, then engine operation is simpler, but torque delivery accuracy and emissions control are reduced
Solution Approach 1:
The system replaces complex mechanical pressure sensing in the cylinder with a simpler thermal measurement approach. By measuring exhaust gas temperature increase from post-injection fuel combustion, the system indirectly determines retained fuel amounts without requiring direct cylinder pressure measurements or complex sensors.
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 enables precise control of fuel injection, improving engine torque and emissions by estimating and adjusting for retained fuel, while also enhancing the control of exothermic reactions during particulate filter regeneration.
Implementation Method 1
The exhaust gas temperature may be increased via injecting post fuel injection amounts into the cylinder that may be expelled to the engine's exhaust system where the fuel may combust within an oxidation catalyst
Implementation Method 2
The particulate filter may be regenerated via increasing exhaust gas temperature and supplying an oxygen rich exhaust mixture to the particulate filter such that soot held within the particulate filter combusts
Data Source
AI summary
Methods and systems for estimating an amount of residual or retained fuel that remains in a cylinder from a first cycle of the cylinder to a second cycle of the cylinder are described. In one example, the amount of residual fuel is estimated in response to a temperature of an oxidation catalyst. The retained fuel amount may then be the basis for adjusting fuel injection amounts during the second cycle of the cylinder.