Fuel Tank Vent Valve Pressure Control
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Solution Overview
Problem
Existing fuel tank systems face difficulties in efficiently detecting perforations and purging the canister, as negative pressure from the engine can hinder the process of vaporized fuel desorption and adsorption.
Innovation Solution
A fuel tank system with a negative pressure open/close valve that maintains an open state during perforation detection and closes during purging, along with a bypass pipe and diaphragm valve configuration, allows efficient communication between the fuel tank and canister, enabling effective perforation detection and canister purging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the vent pipe is used to communicate the fuel tank with the canister during purging, then the structure is simplified, but the negative pressure from the engine cannot efficiently purge the canister
Solution Approach 1:
The vent pipe is divided into two separate pipes: a first vent pipe for perforation detection and a second vent pipe for canister purging. This segmentation allows each pipe to be optimized for its specific function, resolving the contradiction between structural simplicity and purging efficiency.
Solution Approach 2:
A valve is introduced as an intermediary component to control the flow paths. The valve selectively connects or disconnects the fuel tank from the canister via the first or second vent pipe, enabling efficient purging while maintaining structural simplicity through controlled pathways.
2Device complexity
If the same vent pipe is used for both perforation detection and canister purging, then the number of components is reduced, but the functions cannot be performed efficiently
Solution Approach 1:
The single vent pipe function is segmented into two separate pipes: the first vent pipe dedicated to perforation detection and the second vent pipe dedicated to canister purging. This ensures each function has its own optimized pathway, improving reliability while the valve maintains component count control.
Solution Approach 2:
The valve provides multi-functionality by serving as a switching mechanism that directs flow through different pipes for different purposes. This single component enables the system to perform both perforation detection and canister purging efficiently without requiring completely separate systems.
3Ease of operation
If negative pressure from the engine acts on the fuel tank during purging, then the purging process is simplified, but perforation detection becomes difficult
Solution Approach 1:
The system segments the pressure application pathways by using separate vent pipes. The first vent pipe allows negative pressure application for perforation detection without interference from purging operations, while the second vent pipe handles purging, resolving the detection difficulty.
Solution Approach 2:
The valve acts as an intermediary that isolates the fuel tank from engine negative pressure during purging operations. By closing the valve to the first vent pipe during purging, the system prevents negative pressure from interfering with perforation detection while maintaining simplified purging operation through the second vent pipe.
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 enables reliable detection of perforations and efficient purging of the canister by controlling pressure differences and flow rates, ensuring that negative pressure from the engine does not interfere with the fuel tank during purging and that vaporized fuel is effectively adsorbed and desorbed.
Implementation Method 1
a negative pressure pump that is provided at the atmosphere communication pipe, and that causes negative pressure to act on the fuel tank from the canister
Implementation Method 2
a canister in which vaporized fuel generated in the fuel tank is adsorbed and desorbed by an adsorbent
Implementation Method 3
a negative pressure open/close valve that is provided at the vent pipe, that maintains an open state at a pressure difference between a negative pump pressure acting from the negative pressure pump and a tank internal pressure acting from the fuel tank
Data Source
AI summary
A fuel tank system including a fuel tank internally storing fuel, a canister in which vaporized fuel generated in the fuel tank is adsorbed and desorbed by an adsorbent, and open to the atmosphere by an atmosphere communication pipe, a purging pipe placing an engine in communication with the canister, a vent pipe placing the fuel tank in communication with the canister, a negative pressure pump provided at the atmosphere communication pipe, causing negative pressure to act on the fuel tank from the canister, and a negative pressure open/close valve provided at the vent pipe, maintaining an open state at a pressure difference between a negative pump pressure acting from the negative pressure pump and a tank internal pressure acting from the fuel tank, and closing at a pressure difference between a negative purging pressure acting from the engine and the tank internal pressure.