Hydrocarbon Slip Detection via DOC Energy Conversion Ratio
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Solution Overview
Problem
In diesel engines, unburned hydrocarbons can slip over the diesel oxidation catalyst (DOC) and accumulate in the diesel particulate filter (DPF), leading to potential damage and costly repairs during regeneration, as they combust and generate excessive heat, causing cracking or plugging of the DPF and impairing the DOC's functionality.
Innovation Solution
An electronic control module calculates an energy conversion ratio using temperature data from the DOC inlet, outlet, and DPF outlet, comparing it to stored values to estimate hydrocarbon slip, and disables DPF regeneration if the slip exceeds a threshold to prevent damage, using the formula Energy Conversion Ratio = (T2 - T1) / (T3 - T1), where T1 is the DOC inlet temperature, T2 is the DOC outlet temperature, and T3 is the DPF outlet temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If DPF regeneration is performed to burn off accumulated particulate matter, then the DPF is cleaned and restored to functional condition, but unburned hydrocarbons that slipped over the DOC may combust and cause excessive heat leading to DPF cracking or DOC plugging
Solution Approach 1:
The system performs preliminary monitoring of hydrocarbon slip levels before initiating DPF regeneration. By calculating the energy conversion ratio and comparing it to threshold values, the system determines in advance whether hydrocarbon accumulation exists that would pose a risk during regeneration, thereby preventing harmful effects before they occur.
Solution Approach 2:
The system continuously monitors temperature differentials across the DOC and DPF, calculates energy conversion ratios, and uses this feedback to determine whether to proceed with or cancel DPF regeneration. This closed-loop control ensures that regeneration only occurs when safe, preventing hydrocarbon-induced damage while maintaining DPF functionality.
2Reliability
If the system monitors hydrocarbon slip by calculating energy conversion ratio using temperature data, then hydrocarbon levels can be detected to prevent damage, but the system complexity increases due to additional sensors and calculations
Solution Approach 1:
The system uses temperature sensors that are already required for other exhaust system monitoring functions. By calculating the energy conversion ratio from these existing temperature measurements, the system achieves hydrocarbon slip detection without adding dedicated sensors, thereby reducing overall system complexity while maintaining detection accuracy.
Solution Approach 2:
The system uses the thermal energy already present in the exhaust gases during normal operation to provide hydrocarbon monitoring. By measuring temperature differentials that occur naturally during exhaust flow, the system derives hydrocarbon slip information without requiring additional energy input or complex measurement apparatus.
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 method effectively monitors and controls hydrocarbon levels, preventing damage to the DOC and DPF by discontinuing regeneration when excessive hydrocarbon slip is detected, thereby reducing repair costs and maintaining engine performance.
Implementation Method 1
diesel oxidation catalyst (DOC)...unburned hydrocarbons may slip over the DOC
Implementation Method 2
unburned hydrocarbons may slip over the DOC and lodge within, or on a front face of the DPF
Implementation Method 3
receives data indicative of a temperature of a diesel oxidation catalyst input, a temperature of a diesel oxidation catalyst output, and a temperature of a diesel particulate filter output
Implementation Method 4
An energy conversion ratio is calculated with the electronic control module using the data indicative of the temperature of the diesel oxidation catalyst input, the temperature of the diesel oxidation catalyst output, and the temperature of the diesel particulate filter output
Data Source
AI summary
In a method of determining hydrocarbon slip through a diesel oxidation catalyst for an engine having an electronic control module and an exhaust system having a diesel oxidation catalyst and a diesel particulate filter, the electronic control module receives data indicative of a temperature of a diesel oxidation catalyst input, a temperature of a diesel oxidation catalyst output, and a temperature of a diesel particulate filter output. An energy conversion ratio is calculated with the electronic control module using the data indicative of the temperature of the diesel oxidation catalyst input, the temperature of the diesel oxidation catalyst output, and the temperature of the diesel particulate filter output. The calculated energy conversion ratio is compared to stored energy conversion ratio in a memory accessed by the electronic control module. An estimate of hydrocarbon slip through the diesel oxidation catalyst is generated with the electronic control module based upon the comparison of the calculated energy conversion ratio to stored energy conversion ratio.