Evaporative Emission Control Valve Diagnostic Method
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing evaporative emission control systems with notched vapor blocking valves face diagnostic challenges due to gas flow through the notch, making previous diagnostic techniques incompatible and requiring separate calibration for different engine designs, which increases costs and limits system applicability.
Innovation Solution
A diagnostic method that determines the first and second rates of change of the fuel tank vacuum in different states of the vapor blocking valve, allowing for a robust and reliable diagnostic routine that can be applied across various systems without recalibrating thresholds, by comparing these rates to diagnose the operational state of the valve.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If a vapor blocking valve with a notch is used to allow metered fuel vapor flow, then fuel tank pressure buildup is reduced and canister loading during idle-stop is reduced, but previous diagnostic techniques become incompatible and require separate calibration for different engine designs
Solution Approach 1:
The patent changes the diagnostic approach from using absolute pressure thresholds to using relative rate of change measurements. By measuring how quickly pressure changes rather than comparing against fixed thresholds, the system becomes adaptable to different engine designs and notch configurations without requiring recalibration, while still effectively diagnosing vapor blocking valve operational conditions
Solution Approach 2:
The patent creates a universal diagnostic method that works across multiple engine designs and vapor recovery system configurations. The rate of change measurement approach serves as a general solution that accommodates different notch sizes, fuel tank volumes, and canister sizes without requiring system-specific calibration, thereby achieving multi-functionality and broad applicability
2Reliability
If a vapor blocking valve is completely closed during canister purge operation, then canister loading during idle-stop is prevented, but fuel tank pressure buildup occurs
Solution Approach 1:
Instead of completely closing the vapor blocking valve, the patent allows partial vapor flow through the notch during canister purge operation. This partial action prevents complete sealing of the fuel tank, thereby avoiding pressure buildup while still providing sufficient control over canister loading. The notch provides just enough opening to relieve pressure while maintaining effective canister loading management
3Stability of the object's composition
If slowly ramping up vapor purge is used to avoid engine stalls, then engine stability is maintained, but purge efficiency is reduced and canister purging window is smaller
Solution Approach 1:
The patent introduces the vapor blocking valve with a notch as an intermediary component between the fuel tank and canister. This intermediary allows controlled metered vapor flow that prevents sudden vapor spikes (which cause engine stalls) while maintaining adequate purge efficiency. The notch acts as a flow regulator that mediates between the need for engine stability and the need for effective vapor purging
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 provides a common calibration method for a wide range of engines and vehicles, reducing manufacturing costs and increasing diagnostic confidence, while effectively diagnosing the vapor blocking valve's operational condition, including stuck open or closed states, and reducing fuel tank pressure buildup.
Implementation Method 1
The vapor blocking valve may include a breathing component that allows a metered amount of fuel vapor to flow there through when the vapor blocking valve is closed. The breathing component may include a notch in a sealing surface of the vapor blocking valve.
Implementation Method 2
A diagnostic technique for a vapor recovery system may include generating a vacuum in a fuel tank and determining a rate of change of a vacuum in the fuel tank during different states of a vapor blocking valve.
Data Source
AI summary
A method for diagnosing an evaporative emission control system that includes during a first state of a vapor blocking valve, determining a first rate of change of a fuel tank vacuum, during a second state of the vapor blocking valve different from the first state, determining a second rate of change of the fuel tank vacuum, and diagnosing an operational condition of the vapor blocking valve based on the first and second rates of change.