Evaporated Fuel Valve Positioning via Pressure Differential
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Solution Overview
Problem
Existing evaporated fuel processing devices struggle to accurately determine the valve-opening start position of a flow control valve due to variations in fuel tank inner pressure caused by factors like fuel vapor generation and temperature changes, leading to incorrect valve operation.
Innovation Solution
Incorporating an inner pressure sensor and a valve-opening start position determination mechanism that calculates second-order differential values or pressure variations to accurately determine the valve-opening start position, allowing for precise communication between the fuel tank and canister, regardless of environmental changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the valve-opening start position is determined based on the decrease in inner pressure of the fuel tank, then the valve-opening control can be performed, but the determination becomes incorrect when inner pressure varies due to environmental factors or fuel vapor generation
Solution Approach 1:
The patent changes the parameter used for determination from simple pressure decrease detection to second-order differential value calculation. By calculating the rate of change of pressure variation over time, the system can distinguish between normal pressure fluctuations and the specific pressure change pattern that occurs at valve-opening start, thereby improving measurement precision while maintaining operational capability
Solution Approach 2:
The system continuously monitors inner pressure and calculates its second-order differential value in real-time. This feedback mechanism allows the control unit to dynamically identify the valve-opening start position based on the characteristic pattern of pressure change, enabling accurate determination even when baseline pressure varies due to environmental factors or fuel vapor generation
2Reliability
If a flow control valve is used to communicate between fuel tank and canister, then hermetic closure can be achieved, but accurate detection of valve-opening start position becomes difficult due to pressure variations
Solution Approach 1:
The patent transforms the detection approach by changing from direct pressure threshold detection to second-order differential analysis. This parameter transformation allows the system to maintain hermetic closure reliability while overcoming the inability to accurately detect valve-opening start position under varying pressure conditions
Solution Approach 2:
The control unit performs preliminary calculation of the second-order differential value of inner pressure before attempting to determine the valve-opening start position. This preliminary analysis enables the system to anticipate and correctly identify the valve-opening event even when pressure variations are caused by environmental factors or fuel vapor generation rather than valve operation
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
Ensures accurate detection of the valve-opening start position, enabling reliable communication between the fuel tank and canister, even with changes in fuel tank pressure, temperature, or other environmental factors, thereby improving the efficiency and reliability of fuel vapor management.
Implementation Method 1
an inner pressure sensor configured to detect a pressure in an interior space of the fuel tank as an inner pressure
Implementation Method 2
a valve-opening start position determination means configured to calculate a second order differential value of the inner pressure detected by the inner pressure sensor
Implementation Method 3
an evaporated fuel processing device configured to adsorb evaporated fuel in a fuel tank to a canister
Data Source
AI summary
An evaporated fuel processing device includes a flow control valve that is used as a valve to be installed in a pathway connecting a canister and a fuel tank. The device includes an inner pressure sensor configured to detect a pressure in an interior space of the fuel tank as an inner pressure, a valve-opening start position determination means configured to calculate a second order differential value of the inner pressure after a valve opening operation of the flow control valve is started and to determine a valve opening position of the flow control valve as a valve-opening start position when the second order differential value is equal to or greater than a first predetermined value, and a learning means configured to store the valve-opening start position as a learned value that is used when a valve-opening control of the flow control valve is performed.