Fuel Vapor Processing Valve Stroke Learning
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Solution Overview
Problem
Conventional fuel vapor processing apparatuses face low learning accuracy for the valve opening start position of the shutoff valve due to delayed detection of internal pressure reduction in the fuel tank, leading to potential gas leakage from the tank to the canister.
Innovation Solution
The apparatus employs a shutoff valve configuration where the stroke amount is varied in a stepwise fashion by alternating between predetermined strokes in the opening and closing directions, with specific maintenance periods, to improve responsiveness to internal pressure changes and accurately determine the valve opening start position, while independent controls for stroke variation and pressure detection are executed with differing cyclic periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the stroke amount is gradually changed in a continuous manner during learning control, then the valve opening start position can be detected, but the detection time of internal pressure reduction is delayed, resulting in low learning accuracy
Solution Approach 1:
The patent segments the continuous stroke amount change into discrete stepwise changes. The movable valve portion is moved in predetermined stroke increments (e.g., 0.5mm steps) rather than continuously, allowing the system to detect pressure changes at specific discrete positions. This segmentation enables accurate identification of the valve opening start position by comparing pressure readings at each discrete stroke position, thereby improving learning accuracy while reducing detection delay.
Solution Approach 2:
The patent implements periodic action by repeatedly moving the valve between open and closed states at predetermined intervals during the learning control process. The valve is opened to a predetermined position, held for a specified period to allow pressure equilibrium, then closed and held for another period before the next opening cycle. This periodic operation ensures accurate pressure detection at each phase transition point, improving the precision of valve opening start position detection.
2Ease of operation
If the valve is maintained in a relatively largely opened state during learning, then the stroke amount can be adjusted, but the responsiveness to internal pressure variation is reduced, increasing time lag
Solution Approach 1:
The patent applies dynamics by making the valve position dynamic rather than static during the learning process. The valve is repeatedly transitioned between closed and open states in a controlled sequence, allowing the system to observe pressure changes at different dynamic positions. This dynamic operation enables the system to identify the exact stroke position where pressure changes occur, improving both adjustability and responsiveness.
Solution Approach 2:
The patent uses preliminary action by pre-positioning the valve at specific predetermined stroke positions before detection. The valve is moved to known positions (e.g., fully closed, then opened by predetermined increments) and held at each position for a specified time to allow pressure equilibrium. This preliminary positioning ensures that when the valve reaches the opening start position, the pressure change can be detected immediately without lag, while maintaining ease of adjustment through programmable stroke control.
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 enhances the learning accuracy of the valve opening start position, reduces time lag in detecting pressure changes, and minimizes gas flow from the tank to the canister, thereby improving the overall responsiveness and precision of the fuel vapor processing.
Implementation Method 1
a canister provided with an adsorbent material adsorbing fuel vapor produced in a fuel tank
Data Source
AI summary
A fuel vapor processing apparatus includes a canister housing an adsorbent material that adsorbs fuel vapor from a tank, and a valve in a passage connecting the canister and tank. When a stroke amount is within a range, the valve is closed to close the tank and a valve opening start position is learned. In the learning, the stroke amount is varied in the opening direction by repeatedly changing in the opening direction by a first stroke and maintaining for a first time period, and subsequently changing in a closing direction by a second stroke and maintaining for a second time period. The valve opening start position is determined based on the stroke amount in the second time period when the tank pressure is reduced by the predetermined value or more or in a preceding process.