Cold Start Soot Mass Calculation for Gasoline Engines
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Solution Overview
Problem
Current methods for determining soot output from gasoline engines are inadequate, particularly during cold starts, as they rely on hot engine data and fail to accurately capture transient soot emissions, leading to inefficiencies in soot filter maintenance and increased fuel consumption.
Innovation Solution
A method that calculates soot mass by separating it into cold-start and hot-running components, using predefined time periods, engine temperature, and driving conditions, with lookup tables and exponential curves to account for soot accumulation and aggressiveness factors, thereby providing a more accurate total soot mass value.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If steady state or hot engine dynamometer test data is used to determine soot output, then the measurement method is simple, but the measurement precision is poor because it does not accurately capture cold start soot emissions which account for up to 90% of total soot output
Solution Approach 1:
The patent segments the soot measurement into two distinct parts: cold start soot mass (determined from engine coolant temperature using lookup tables) and hot engine soot mass (calculated from brake specific soot mass, engine power, and driving aggressiveness factor). This segmentation allows each part to be measured using methods optimized for its specific conditions, thereby improving overall measurement precision without requiring a completely complex new system.
Solution Approach 2:
The patent performs preliminary action by pre-generating hot engine soot mapping data from dynamometer testing and storing it in lookup tables before actual vehicle operation. This pre-computed data is then quickly referenced during cold starts, avoiding the need for complex real-time calculations while maintaining accuracy. The driving aggressiveness factor is also pre-defined for different driving conditions.
2Measurement precision
If cold start soot emissions are accurately measured, then the total soot mass determination becomes more accurate, but the calculation complexity increases due to need to separate cold start and hot engine periods
Solution Approach 1:
The calculation process is segmented into distinct time periods: cold start period (from engine start until coolant temperature reaches a threshold) and hot engine period (remaining operation time). Each period has its own simplified calculation method, avoiding the need for complex continuous modeling while achieving accurate total soot mass determination.
Solution Approach 2:
The patent changes the calculation parameters based on engine temperature state. During cold start, soot mass is determined primarily from coolant temperature using pre-stored lookup tables. During hot engine operation, the calculation uses brake specific soot mass, engine power, and driving aggressiveness factor. This parameter change approach simplifies calculations for each regime while maintaining overall accuracy.
3Reliability
If soot burn operations are performed frequently to prevent soot filter replacement, then the soot filter maintenance is ensured, but the fuel consumption increases
Solution Approach 1:
The patent implements feedback by continuously monitoring and calculating the accumulated soot mass in real-time based on actual driving conditions, cold start events, and engine power. This accurate feedback information allows the system to determine the optimal timing for soot burn operations, triggering them only when necessary to prevent filter saturation, thereby avoiding unnecessary fuel consumption while ensuring filter reliability.
Solution Approach 2:
The system performs self-service by autonomously tracking soot accumulation and managing the soot filter maintenance schedule without requiring external intervention or conservative over-maintenance. The accurate soot mass calculation enables the system to service the filter only when truly needed, optimizing the balance between reliability and energy consumption.
Data Source
AI summary
A method to determine soot mass of a gasoline engine powered automobile vehicle includes: predefining a time period between approximately 50 seconds to 200 seconds defining a cold start operation of a gasoline engine; determining a critical engine cold start temperature at a time defining a start of the cold start operation; identifying a cold start soot mass value from a lookup table based on the predefined time period and the critical engine cold start temperature; calculating a hot engine soot mass value for a hot engine operating time; repeating the calculating step for at least one next successive hot engine operating time; and adding the cold start soot mass value to the hot engine soot mass value for the hot engine operating time and the at least one next successive hot engine operating time to define a total soot mass value.