Non-Road Engine Carburetor Control to Prevent Tip-Over Fuel Leakage
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Solution Overview
Problem
Existing non-road engines face challenges in preventing fuel leakage and evaporative emissions when they tip over during shutdown, which are not adequately addressed by previous environmental standards.
Innovation Solution
A non-road engine design featuring a control valve and combination switch that controls the fuel supply between the fuel tank and carburetor, with the control valve opening or closing the main jet based on the switch's state, ensuring fuel is not discharged when the engine tips over, and incorporating an elastic seal and return spring to maintain the main jet closed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the engine uses a traditional fuel supply system without a control valve, then the structure is simple and easy to manufacture, but fuel leakage occurs when the engine tips over during shutdown
Solution Approach 1:
The control valve is activated in advance when the combination switch is turned off during shutdown, closing the main jet before the engine actually stops. This preliminary action ensures that when the engine tips over, the fuel supply is already cut off and the main jet is closed, preventing fuel leakage. The return spring maintains the closed state as a default safety position.
2Reliability
If the main jet remains open during shutdown, then the engine can be restarted quickly, but fuel is discharged through the main jet when the engine tips over causing fuel leakage
Solution Approach 1:
The control valve closes the main jet in advance when the combination switch is turned off, before the engine actually stops running. This preliminary closing action prevents fuel leakage during tip-over while the engine is still running, and the engine can still be restarted quickly by simply turning the combination switch back on, which opens the control valve and restores fuel flow.
3Reliability
If the fuel supply pipe remains connected between fuel tank and carburetor during shutdown, then fuel flow is maintained for quick restart, but fuel leaks through the fuel circuit when engine tips over
Solution Approach 1:
The control valve closes the main jet in advance when the combination switch is turned off, preventing fuel leakage through the fuel circuit during tip-over. The fuel supply pipe remains physically connected for quick restart, but the closed main jet blocks fuel flow. Restarting is convenient - simply turn the combination switch back on to open the control valve and restore fuel flow immediately.
4Reliability
If the control valve and combination switch are mechanically linked, then the linkage is reliable and heat-resistant, but the device complexity increases
Solution Approach 1:
The control valve and combination switch are mechanically linked through a simple cable connection rather than a complex mechanical linkage system. This cable-based mechanical connection provides sufficient reliability and heat resistance while minimizing the increase in device complexity. The cable transmits the switching action from the combination switch to the control valve efficiently.
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 design effectively prevents fuel leakage and reduces evaporative emissions, meeting environmental requirements and enhancing reliability by ensuring the fuel supply is cut off and the main jet is closed during engine shutdown.
Implementation Method 1
the control valve is provided with a return spring that causes the needle valve stem to maintain a trend of closing the main jet
Implementation Method 2
the movable part is linked and matched with the needle valve stem through a cable
Data Source
AI summary
A non-road engine is provided. The non-road engine includes a carburetor and a combination switch for controlling on-off of a fuel supply pipe between a fuel tank and the carburetor, where the carburetor is provided with a control valve for controlling opening and closing of a main jet; the control valve is linked and matched with the combination switch; when the combination switch is in an on state, the control valve causes the main jet to be in an open state; and when the combination switch is in an off state, the control valve causes the main jet to be in a closed state.