Fuel Supply Device Bypass Passage for Engine Starting
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Solution Overview
Problem
Conventional fuel supply devices for engines face challenges in starting the engine quickly, especially when the fuel pump impedes flow during a stop period, leading to delayed engine starting due to insufficient head difference between fuel levels, which can result in user misjudgment of engine failure.
Innovation Solution
A fuel supply device with a bypass passage that allows direct fuel supply to the carburetor before the fuel pump starts, utilizing an on-off valve and restricting portions to manage fuel flow, ensuring reliable fuel delivery without increasing the head difference between fuel levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the fuel pump is disposed on the fuel supply conduit, then fuel can be supplied to the carburetor, but the fuel pump impedes flow through the conduit during a stop period, thereby obstructing fuel supply to the carburetor
Solution Approach 1:
The fuel supply system is segmented into two independent pathways: the main fuel supply conduit passing through the fuel pump and a bypass passage avoiding the fuel pump. This segmentation allows the system to utilize different supply methods depending on operational requirements - direct gravity flow during stop periods and pumped supply during operation, thereby resolving the contradiction between reliable fuel supply and adequate flow speed.
2Reliability
If the head difference between fuel levels is increased to enable fuel supply before the fuel pump starts, then fuel supply is improved, but the space necessary for providing the fuel tank is exceeded
Solution Approach 1:
The bypass passage acts as an intermediary pathway that enables fuel to reach the carburetor before the fuel pump operates. By providing this alternative route that does not rely on increased head difference, the system achieves reliable fuel supply timing without requiring excessive vertical space for the fuel tank, thus resolving the contradiction between fuel supply timing and space constraints.
3Stability of the object's composition
If the fuel pump is started immediately after the engine, then fuel supply is stabilized, but the carburetor contains no fuel therein during the stop period, causing delayed engine starting
Solution Approach 1:
The bypass passage enables preliminary fuel supply to the carburetor before the fuel pump is activated. Fuel flows through the bypass passage under gravity during the stop period, ensuring the carburetor contains sufficient fuel when the engine is started. This preliminary action eliminates the delay caused by waiting for the fuel pump to prime the system, thereby resolving the contradiction between fuel supply stability and engine starting time.
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
Improves engine starting characteristics by enabling automatic fuel supply to the carburetor before the fuel pump activates, stabilizing fuel delivery even when the fuel level is low, and preventing fuel supply failures, thus enhancing operational reliability.
Implementation Method 1
a fuel pump arranged to supply fuel from the fuel tank to the carburetor
Implementation Method 2
the fuel tank is positioned such that an fuel level in the fuel tank is higher than an fuel level in a float chamber in a carburetor so that fuel is supplied from the fuel tank to the carburetor using the head difference between the fuel levels
Data Source
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AI summary
The present invention relates to a fuel supply device for an engine, the fuel supply device comprising: a carburetor (20) having a float chamber (20b), a fuel tank (24) configured to contain fuel, the fuel tank (24) being positioned such that, at least when the fuel tank (24) is full with fuel, a fuel level in the fuel tank (24) is higher than a minimum required fuel level in the float chamber (20b) of the carburetor (20), a fuel pump (25) arranged to supply fuel from the fuel tank (24) to the carburetor (20), and a bypass passage (35) that bypasses the fuel pump (25).