Fuel Vapor Purge Valve Flow Characteristic Correction
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Solution Overview
Problem
Existing fuel vapor treatment apparatuses face challenges in maintaining a target air-fuel ratio due to variations in the flow characteristic of the purge valve, leading to deviations in the actual air-fuel ratio, even when the opening degree of the purge valve and fuel injection amount are controlled based on preset flowrate characteristics and fuel vapor concentration.
Innovation Solution
The apparatus adjusts the opening degree of the purge valve and fuel injection amount based on the flow characteristic of the purge valve and fuel vapor concentration, with a computer system continuously comparing the actual and target air-fuel ratios and correcting the flow characteristic to minimize differences, ensuring accurate air-fuel ratio control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the opening degree of the purge valve and fuel injection amount are controlled based on preset flowrate characteristics, then the control system is simple to operate, but the actual air-fuel ratio may deviate from the target air-fuel ratio due to dispersion or aging of the purge valve flow characteristic
Solution Approach 1:
The control device measures the actual air-fuel ratio using an air-fuel ratio sensor and compares it with the target air-fuel ratio. Based on the deviation detected, the control device adjusts the opening degree of the purge valve and/or fuel injection amount to correct the air-fuel ratio, forming a closed-loop feedback system that maintains precise control despite valve characteristics changing over time or between units
Solution Approach 2:
The control device dynamically changes operational parameters (opening degree of purge valve and fuel injection amount) based on real-time measurements of actual air-fuel ratio. This allows the system to adapt to variations in purge valve flow characteristics without requiring physical adjustment or replacement of components
2Device complexity
If the opening degree of the purge valve is controlled based on a preset flowrate characteristic to obtain the target air-fuel ratio, then the control process is straightforward, but the amount of fuel vapor purged from the canister may be different from the target value
Solution Approach 1:
The control device continuously monitors the actual air-fuel ratio and uses this feedback information to adjust the purge valve opening degree and fuel injection amount. This closed-loop control compensates for manufacturing variations in purge valve flow characteristics, ensuring consistent air-fuel ratio control across different units without requiring complex hardware modifications
Solution Approach 2:
The control system automatically adjusts itself based on measured air-fuel ratio deviations. The control device performs self-correction by modifying purge valve opening and fuel injection parameters, eliminating the need for manual calibration or adjustment during manufacturing or operation
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 effectively reduces the difference between the actual and target air-fuel ratios, even with dispersion or aging of the purge valve's flow characteristic, thereby maintaining optimal engine performance.
Implementation Method 1
a canister that temporarily adsorbs fuel vapor generated in the fuel tank
Implementation Method 2
The fuel vapor desorbed from the canister is introduced and purged, through a purge passage, into an intake passage
Implementation Method 3
an air-fuel ratio sensor that detects an actual air-fuel ratio of the engine
Data Source
AI summary
A CPU measures an actual air-fuel ratio based on the signals detected by the air-fuel ratio sensor. When the difference between the actual air-fuel ratio and a target air-fuel ratio is larger than a predetermined value, the computer determines that a fuel vapor amount purged into the intake passage deviates from a target value due to an incorrectness of a reference flow quantity of the purge valve. The computer calculates an actual reference flow quantity based on a measured actual air-fuel ratio, and rewrites the reference flow quantity corresponding to a current intake pressure into the calculated the reference flow quantity. Thereby, the difference between the actual air-fuel ratio and the target air-fuel ratio can be reduced.