Upstream Purge Line Diagnostic Apparatus for Evaporative Fuel Systems
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Solution Overview
Problem
Existing diagnostic apparatuses for evaporative fuel processing systems face challenges in accurately performing purge-flow diagnoses, especially when turbocharging is temporarily interrupted, leading to erroneous results due to response delays and ineffective time inclusion in accumulative measurements.
Innovation Solution
The diagnostic apparatus includes a fuel tank, canister, upstream purge line, upstream purge valve, pressure detector, valve controller, and timekeeping units to accurately measure the time pressure decreases in the upstream purge line, excluding response delays and ensuring accurate diagnosis regardless of turbocharger operational states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the accumulative time measurement includes response delay time from valve opening command to actual pressure decrease, then the measurement is simpler, but the diagnostic accuracy deteriorates
Solution Approach 1:
The patent extracts and separates the response delay time from the accumulative time measurement. The determination unit specifically identifies and excludes the period from when the opening command is output to when the pressure actually starts decreasing, measuring only the effective suction time. This extraction eliminates the source of measurement error while maintaining a relatively simple system structure.
Solution Approach 2:
The patent uses feedback from the pressure detector to identify when the pressure actually starts decreasing. By monitoring the pressure change in real-time and using this feedback to determine the start of effective suction time, the system accurately distinguishes between response delay and actual purge flow, thereby improving diagnostic accuracy without significantly increasing complexity.
2Adaptability or versatility
If the diagnosis is performed during intermittent turbocharging conditions, then the system adaptability is improved, but the diagnostic reliability deteriorates due to turbocharger operation interruptions
Solution Approach 1:
The patent implements a dynamic diagnosis approach where the determination unit continuously monitors pressure changes and accumulative time even when turbocharging is interrupted. The system adapts to changing operational conditions by resuming the diagnosis when conditions are met again, rather than requiring continuous uninterrupted turbocharging. This dynamic approach maintains reliability across intermittent operating conditions.
Solution Approach 2:
The patent prepares the diagnosis system in advance by continuously tracking relevant parameters and being ready to execute the determination when conditions are satisfied. The system pre-establishes the diagnostic framework and continues monitoring during interruptions, so that when turbocharging resumes, the diagnosis can proceed without significant delay or loss of reliability.
3Duration of action of stationary object
If the accumulative time includes periods when diagnosis execution condition is not satisfied, then the measurement is more continuous, but the time measurement accuracy deteriorates
Solution Approach 1:
The patent extracts and excludes periods when the diagnosis execution condition is not satisfied from the accumulative time measurement. The determination unit specifically measures only the time when both the execution condition is met and pressure is actively decreasing, separating this effective time from periods of interruption or inactivity. This extraction ensures accurate measurement of actual purge flow duration.
Solution Approach 2:
The patent implements periodic evaluation of the diagnosis execution condition, continuously checking whether the conditions for accurate measurement are satisfied. By periodically assessing the execution condition and only accumulating time when conditions are met, the system maintains measurement precision while still providing continuous monitoring capability across different operational states.
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 solution enables more precise purge-flow diagnosis of the upstream purge line by accurately measuring effective suction time, reducing erroneous diagnoses and improving diagnostic accuracy even during intermittent turbocharging conditions.
Implementation Method 1
The canister is configured to communicate with the fuel tank and is capable of adsorbing evaporative fuel generated in the fuel tank
Implementation Method 2
The pressure detector is configured to detect pressure in the upstream purge line
Implementation Method 3
If the pressure in the upstream purge line detected by the pressure detector decreases by a predetermined pressure or more from the start of the diagnosis until an accumulative time measured by the first timekeeper reaches a predetermined time
Data Source
AI summary
A diagnostic apparatus includes a fuel tank; a canister adsorbing evaporative fuel; an upstream purge line allowing the canister and an engine intake system to communicate upstream of a pressure charger; an upstream purge valve that opens and closes the upstream purge line; a pressure detector detecting pressure in the upstream purge line; a valve controller that opens and closes the upstream purge valve during pressure-charging and non-pressure-charging; a timekeeper measuring an accumulative time in which a diagnosis execution condition is satisfied after a purge-flow diagnosis starts; and a determiner determining whether evaporative fuel processing system operates normally or abnormally depending on whether the pressure decreases by a predetermined pressure or more from the start of the diagnosis. Every time the upstream purge valve opens after the condition is satisfied, the timekeeper measures the accumulative time after a predetermined delay time elapses from when a valve opening command is output.