Evaporated Fuel Processing Valve Opening Position Determination
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Solution Overview
Problem
Existing evaporated fuel processing devices using flow control valves struggle to accurately determine the valve-opening start position when the differential pressure between the fuel tank's inner pressure and atmospheric pressure is small, leading to incorrect determination.
Innovation Solution
Incorporating an inner pressure sensor to detect gage pressure, a valve-opening start position determination means that changes the flow control valve's stroke amount only when the pressure variation exceeds a predetermined value, and a learning means to store this position, ensuring the valve-opening start position is determined under sufficient differential pressure conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the valve-opening start position is determined based on the decrease in the inner pressure of the fuel tank, then the valve-opening start position can be detected, but the determination becomes incorrect when the differential pressure between the inner pressure of the fuel tank and the atmospheric pressure is small
Solution Approach 1:
The patent changes the determination criterion from absolute pressure decrease to pressure decrease rate (dP/dt). By monitoring the rate of pressure change rather than the absolute pressure value, the system can accurately detect the valve-opening start position even when the differential pressure is small, as the rate of change provides a more sensitive indicator of valve movement.
Solution Approach 2:
The patent replaces the mechanical pressure detection approach with a computational analysis of pressure sensor data. Instead of relying on absolute pressure thresholds, the system uses microprocessor-based analysis to calculate the rate of pressure change, substituting mechanical determination with electronic computation to improve accuracy under varying pressure conditions.
2Reliability
If the flow control valve is used to connect the fuel tank and canister, then the fuel tank can be hermetically closed, but the valve-opening start position cannot be accurately determined when the differential pressure is small
Solution Approach 1:
The patent implements a feedback mechanism where the pressure sensor continuously monitors the inner pressure of the fuel tank and feeds this information back to the control system. The system analyzes the rate of pressure change in real-time to detect the valve-opening start position, creating a closed-loop feedback system that improves detection accuracy regardless of the differential pressure conditions.
Solution Approach 2:
The patent performs preliminary monitoring of the pressure change rate before the valve actually opens. By continuously analyzing the rate of pressure change and comparing it against predetermined thresholds, the system prepares to detect the valve-opening start position in advance, ensuring accurate detection even when the differential pressure is small and the pressure change is subtle.
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
Prevents incorrect determination of the valve-opening start position by ensuring it is determined only when the inner pressure of the fuel tank is significantly different from atmospheric pressure, enhancing the accuracy and reliability of the valve-opening control.
Implementation Method 1
an inner pressure sensor configured to detect a pressure in an interior space of the fuel tank
Data Source
AI summary
An evaporated fuel processing device configured to adsorb evaporated fuel in a fuel tank to a canister and to feed the adsorbed evaporated fuel to an engine. The device includes an inner pressure sensor configured to detect a pressure in an interior space of the fuel tank, a valve-opening start position determination means configured to change the stroke amount of a flow control valve from an initial condition and to determine a valve-opening start position of the flow control valve based on a requirement that a range of variation of the inner pressure is equal to or greater than a predetermined value, a learning means configured to store the valve-opening start position, and a prohibition means configured to prohibit the valve-opening start position determination means from determining the valve-opening start position when the inner pressure falls within a predetermined pressure range relative to the atmospheric pressure.