Purge Line Blockage Detection via Dynamic Pressure Rate
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Solution Overview
Problem
Existing blockage detection systems for fuel vapor purge lines in internal combustion engines face challenges in accurately detecting blockages due to fixed predetermined periods, which can lead to excessive decompression and reduced durability or inaccurate detection.
Innovation Solution
A blockage detection system that uses a computer to control negative pressure in the purge line and determines blockages based on the flow rate of inner fluid, exceeding or falling below a threshold after pressure reduction, allowing for adjustable pressure settings to prevent excessive decompression and enhance detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a fixed predetermined period is used for blockage detection, then the detection process is simple, but it causes excessive decompression reducing durability or inaccurate blockage detection
Solution Approach 1:
The patent applies dynamics by transitioning from a fixed predetermined period to a dynamic detection method that adjusts the detection timing based on actual pressure changes. The computer determines blockage based on whether the pressure change rate exceeds a threshold during the decompression process, allowing the detection to adapt to varying system conditions and prevent both excessive decompression and inaccurate detection.
Solution Approach 2:
The patent changes the detection parameter from a fixed time-based approach to a rate-based approach. Instead of using a predetermined fixed period, the system monitors the pressure change rate (dP/dt) and compares it against a threshold. This parameter change enables more precise detection that adapts to actual system behavior, resolving the contradiction between simplicity and reliability.
2Measurement precision
If a long predetermined period is used, then blockage detection accuracy is improved, but excessive decompression occurs affecting durability
Solution Approach 1:
The patent implements feedback by continuously monitoring the pressure change rate during decompression and using this information to determine blockage. The system provides feedback on the actual decompression behavior and adjusts the detection decision based on whether the rate exceeds the threshold, preventing excessive decompression while maintaining detection accuracy.
Solution Approach 2:
The system uses dynamic monitoring of the pressure change rate during the decompression process, rather than relying on a fixed predetermined period. This dynamic approach allows the system to detect blockage at the appropriate moment without causing excessive decompression, thus improving both accuracy and durability.
3Reliability
If a short predetermined period is used, then durability is improved by avoiding excessive decompression, but blockage detection accuracy decreases
Solution Approach 1:
The patent changes the detection parameter from fixed time duration to pressure change rate threshold. This parameter change allows the system to maintain short detection periods for durability while achieving high detection accuracy by monitoring whether the pressure change rate exceeds the threshold, rather than relying on prolonged decompression.
Solution Approach 2:
The patent replaces the mechanical time-based detection approach with a rate-based computational approach. Instead of using a fixed predetermined period, the computer calculates the pressure change rate and compares it against a threshold, substituting the mechanical timing mechanism with a more sophisticated computational method that improves both durability and accuracy.
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
The system improves durability and accuracy of blockage detection in fuel vapor purge lines by dynamically controlling negative pressure and calculating flow rates using exhaust speed and elapsed time, enabling effective detection even with changes in the negative pressure pump or atmospheric pressure.
Implementation Method 1
a negative pressure source that supplies negative pressure to the purge line
Data Source
AI summary
A blockage determination portion 174 of a blockage detection system 30 determines that no blockage has occurred in a purge line 90, if a flow rate V of an inner fluid Fi exceeds a flow rate threshold THv while an internal pressure Pi of the purge line 90 is reduced from a first pressure value P1 to a second pressure value P2, for example. The blockage determination portion 174 determines that a blockage has occurred in the purge line 90, if the flow rate V of the inner fluid Fi falls below the flow rate threshold THv after the internal pressure Pi is reduced from the first pressure value P1 to the second pressure value P2.