Evaporative Emission Control Flow Volume Calculation
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Solution Overview
Problem
Current evaporative emission control systems in motor vehicles, particularly those with canister-purge valves, face inaccuracies in determining fluid flow volume due to manufacturing tolerances, leading to inefficiencies in combustion engine performance and increased pollutant emissions, and are costly to maintain.
Innovation Solution
A method that uses pressure sensors to measure evaporative emission control system pressure and ambient pressure, combined with computational devices to calculate the fluid flow volume through the canister-purge valve, allowing for precise control of the fuel supply to the combustion engine, thereby compensating for component variances and reducing the need for additional purge air pumps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a canister-purge valve is used in the evaporative emission control system, then the system is less complex and more economical to manufacture, but accurate determination of fluid flow volume is not possible due to manufacturing tolerances
Solution Approach 1:
The patent replaces mechanical measurement methods with a computational approach. Instead of using complex mechanical flow meters or highly precise mechanical valves, the system uses pressure sensors to measure pressure differential across the canister-purge valve and a control device with a computational algorithm to calculate the actual fluid flow volume, thereby achieving accurate measurement without complex mechanical systems
Solution Approach 2:
The patent changes the measurement parameter from direct flow volume measurement to pressure differential measurement. By measuring pressure upstream and downstream of the canister-purge valve and computing the flow volume from the pressure differential using a calibrated relationship, the system achieves accurate flow determination while maintaining simple hardware
2Ease of manufacture
If component variances in the evaporative emission control system are not considered, then the system is simpler to manufacture, but inaccuracies in supplied air mass and fuel mass result in poor mixture formation
Solution Approach 1:
The patent implements a feedback control system where the control device continuously determines the actual fluid flow volume through the canister-purge valve using pressure measurements and a computational algorithm, then uses this feedback information to adjust the fuel injection quantity, thereby compensating for component variances and achieving accurate mixture formation despite manufacturing tolerances
3Reliability
If lambda control is used to correct combustion continuously, then combustion quality is maintained, but performance and efficiency are negatively affected due to constant correction delays
Solution Approach 1:
The patent performs preliminary action by pre-calculating and determining the actual fluid flow volume before the combustion cycle requires correction. By using pressure differential measurements and a computational algorithm to predict the actual air mass entering the engine, the control device can pre-adjust the fuel injection quantity, eliminating the need for continuous lambda control corrections and avoiding performance losses from constant adjustment delays
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 accurate and cost-effective control of the fuel quantity supplied to the combustion engine, improving efficiency and reducing pollutant emissions while eliminating the need for complex and costly additional purge air pumps.
Implementation Method 1
an actual evaporative emission control system pressure upstream of the canister-purge valve is determined by a pressure sensor
Implementation Method 2
A flow volume of a fluid streaming through the canister-purge valve is computed on the basis of the actual evaporative emission control system pressure and an actual ambient pressure
Data Source
AI summary
A method for operating a drive system of a motor vehicle having a combustion engine, a fuel tank, and an evaporative emission control system, includes the following steps: opening a canister-purge valve of the evaporative emission control system; using a first sensor of the motor vehicle designed as a pressure sensor to ascertain an evaporative emission control system pressure prevailing in the evaporative emission control system between a filter device of the evaporative emission control system and the canister-purge valve; using a measurement device of the motor vehicle to ascertain an ambient pressure of the motor vehicle; using a computational device of the motor vehicle to compute a flow volume of a fluid streaming through the canister-purge valve on the basis of the ascertained evaporative emission control system pressure and the ascertained ambient pressure; and using an engine control device of the drive system of the motor vehicle to operate the drive system taking into account the computed fluid flow volume.