Dual Fuel Selector Switch

What is this patent about?

’390 is related to the field of dual-fuel generators, specifically addressing the problem of preventing the simultaneous use of two different fuel sources. Dual-fuel generators are designed to run on either gasoline or liquefied petroleum gas (LPG), offering flexibility in fuel selection. However, existing systems with separate valves for each fuel lack a mechanism to positively prevent both valves from being open at the same time, which could lead to an unsafe mixing of fuels.

The underlying idea behind ’390 is to mechanically interlock the fuel selection process, ensuring that only one fuel source can be active at any given time. This is achieved through a sliding selector switch that physically blocks the valve handle of the inactive fuel source. The switch is designed such that moving it to select one fuel automatically prevents the other fuel's valve from being opened.

The claims of ’390 focus on a fuel selector mechanism that includes a selector switch with two modes: one enabling fuel flow from a first fuel source and another enabling fuel flow from a second fuel source. The claims also cover an interlock that prevents simultaneous operation of the fuel selector switches. The key is the mechanical linkage that makes it physically impossible to have both fuel sources supplying fuel to the engine at the same time.

In practice, the fuel selector includes a sliding switch positioned adjacent to the valve handles for each fuel source. When the switch is in the 'gasoline' position, it covers and locks the LPG valve handle in the OFF position, preventing it from being opened. Conversely, when the switch is moved to the 'LPG' position, it covers and locks the gasoline valve handle. This mechanical interlock ensures that only one fuel valve can be in the ON position at any given time.

This design differs from prior approaches that rely on the operator to manually ensure only one fuel valve is open. By introducing a physical barrier, the invention eliminates the possibility of human error and prevents the unsafe mixing of fuels. Furthermore, the design incorporates a carburetor solenoid switch that shuts off the gasoline flow when the selector switch is moved to the LPG position, providing an additional layer of safety and preventing any residual gasoline from entering the engine when it's running on LPG.