Fuel Tank Isolation Valve Position Diagnosis via Vacuum Feedback
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Solution Overview
Problem
In hybrid vehicles, the reduced engine operation times lead to insufficient purging of fuel vapors from the emission control system, and the position of the fuel tank isolation valve (FTIV) may not be known without an additional sensor, resulting in inaccurate adjustments.
Innovation Solution
A method is implemented to diagnose the position of the FTIV by sending electrical pulses and applying a vacuum to the fuel system, using a vacuum pump to verify if the valve is open or closed, and subsequently adjusting it to the desired position based on the diagnosis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the FTIV is adjusted without position verification, then the valve can be actuated quickly, but the position accuracy deteriorates
Solution Approach 1:
The patent implements feedback by applying vacuum to the fuel system and sensing whether the vacuum is achieved. This feedback mechanism verifies the actual position of the FTIV after actuation, allowing the system to confirm whether the valve is open or closed based on vacuum sensing, thereby resolving the position accuracy issue without requiring additional position sensors
Solution Approach 2:
The system uses the vacuum pump and vacuum sensing capabilities that already exist in the fuel system for the dual purpose of both fuel system operation and valve position verification. This self-service approach allows position diagnosis using existing system components rather than requiring separate dedicated sensing mechanisms
2Measurement precision
If an additional position sensor is added to the FTIV, then the valve position can be accurately diagnosed, but the device complexity increases
Solution Approach 1:
The patent makes the vacuum pump and vacuum sensing system multi-functional by using them for both their primary fuel system function and for FTIV position diagnosis. This universality eliminates the need for dedicated position sensing components, maintaining system simplicity while achieving accurate position verification
Solution Approach 2:
The existing vacuum system serves itself by providing position diagnostic capability through its normal operation. The vacuum pump and pressure sensor that are already part of the fuel system are utilized to infer valve position, allowing the system to diagnose its own state without external or additional sensing components
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 increases the accuracy of FTIV control by determining its position and preventing degradation, ensuring effective purging of fuel vapors and maintaining system efficiency.
Implementation Method 1
applying a vacuum to the fuel system
Implementation Method 2
creating a pressure difference that verifies the position of the FTIV
Implementation Method 3
adjusting the FTIV to a desired position based on the diagnosis
Data Source
AI summary
Methods and systems are provided for adjusting and diagnosing a position of a fuel tank isolation valve of a fuel system. In one example, a method may include adjusting the fuel tank isolation valve via electrical pulses and tracking a position of the FTIV by counting each of the electrical pulses. When a vacuum is created in the fuel system, the method may include verifying the position of the FTIV based on resulting fuel system pressures.