Straddle Vehicle Evaporated Fuel Control Device
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Solution Overview
Problem
In straddle type vehicles, connecting the fuel tank and engine with an evaporated fuel passage poses risks of liquid fuel flowing into the engine or engine oil flowing into the fuel tank, especially when the vehicle swings, affecting the vehicle's design and rider comfort.
Innovation Solution
The evaporated fuel control device positions the vaporized fuel passage with its uppermost portion higher than the fuel and oil levels, using an S-shaped pipe and check valves to prevent fluid flow between the fuel tank and engine, while adapting to the vehicle's layout to maintain a low footrest position and efficient gas-liquid separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the fuel tank is located at a high position to prevent liquid fuel from flowing into the engine, then liquid fuel flow prevention is improved, but the footrest portion position must be high which deteriorates rider comfortableness
Solution Approach 1:
The patent introduces an intermediary structure (the vaporized fuel passage with upward slope and check valve) between the fuel tank and engine to prevent liquid fuel flow. The passage is configured to slope upward from the fuel tank connection toward the engine, creating a physical barrier that prevents liquid fuel from reaching the engine while allowing vaporized fuel to pass through when the engine is running.
Solution Approach 2:
The patent changes the parameter of the vaporized fuel passage configuration, specifically making it slope upward from the fuel tank side toward the engine. This parameter change creates a natural barrier against liquid fuel flow while maintaining the ability to transport vaporized fuel, thus preventing liquid fuel leakage without requiring the fuel tank to be positioned high.
2Productivity
If the vaporized fuel passage is connected at the shortest distance between the fuel tank and engine, then connection efficiency is improved, but liquid fuel may flow into the engine or oil into the fuel tank when the vehicle swings, deteriorating reliability
Solution Approach 1:
The patent adds a vertical dimension to the vaporized fuel passage configuration by making it slope upward from the fuel tank toward the engine. Instead of a horizontal or downward connection, the passage rises upward, creating a height difference that prevents liquid fuel and oil from flowing between the fuel tank and engine even when the vehicle swings, while still maintaining efficient vapor transport.
Solution Approach 2:
The upward-sloping vaporized fuel passage acts as an intermediary structure that mediates between the fuel tank and engine. It provides a controlled pathway for vaporized fuel while its upward slope and check valve configuration prevent unwanted liquid fuel and oil flow, thus ensuring reliability without sacrificing connection efficiency.
3Reliability
If a canister is mounted to adsorb evaporated fuel, then evaporated fuel control is improved, but the vehicle body design is restricted and the vehicle body becomes large in size, deteriorating compactness
Solution Approach 1:
The patent extracts the canister component from the evaporated fuel control system and replaces it with a simplified vaporized fuel passage that directly connects the fuel tank to the engine. By removing the canister, the system achieves evaporated fuel control without requiring additional mounting space or increasing vehicle body size, thus maintaining compactness while ensuring reliability.
Solution Approach 2:
The vaporized fuel passage serves multiple functions: it transports vaporized fuel from the fuel tank to the engine, prevents liquid fuel flow, prevents oil backflow, and eliminates the need for a separate canister. This multi-functionality allows the system to maintain reliable evaporated fuel control while keeping the vehicle body compact.
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 configuration effectively prevents liquid fuel from entering the engine and engine oil from entering the fuel tank, ensuring rider comfort and optimizing the vehicle's design by using available space for the vaporized fuel passage, while maintaining internal pressure balance in the fuel tank.
Implementation Method 1
the uppermost portion is disposed at a position higher than a fuel upper limit level of the fuel tank, an oil upper limit level in the engine and the footrest portion
Data Source
AI summary
There is provided a vaporized fuel control device for a straddle type vehicle that can prevent a situation that liquid fuel in a fuel tank flows into an engine and a situation that oil in the engine flows into the fuel tank while adapting the vaporized fuel control device to the layout of the straddle vehicle. A vaporized fuel passage 110 is disposed so as to have an uppermost portion X at some position thereof between the fuel tank 35 and the engine E, and the uppermost portion X is disposed at a higher position than the fuel upper limit level of the fuel tank 35, the oil upper limit level in the engine E and a footrest portion 44.