Fuel shutoff system

What is this patent about?

'083 is related to the field of internal combustion engines, specifically those used in small utility applications like lawn mowers and generators. These engines often suffer from issues like wasted fuel, increased emissions, and backfiring due to unburned fuel being drawn into the combustion chamber after the engine is shut down. Prior art solutions, such as solenoid valves or throttle-based fuel blockers, have drawbacks like requiring a battery, interfering with the engine governor, or not completely preventing fuel flow from the fuel bowl.

The underlying idea behind '083 is to mechanically block the fuel supply downstream of the fuel bowl, close to the fuel nozzle, upon engine shutdown. This is achieved using a blocking member that physically obstructs the fuel conduit, preventing fuel from reaching the intake valve. The key insight is to provide a simple, reliable, and inexpensive fuel shutoff mechanism that doesn't rely on electrical components or interfere with the engine's existing governor system.

The claims of '083 focus on a fuel shutoff system for an internal combustion engine with a carburetor, fuel bowl, intake valve, and a fuel conduit. The system includes a blocking member positioned to selectively block the fuel conduit downstream of the fuel bowl, preventing fuel passage to the intake valve. A manually-operable control actuates the blocking member. Crucially, the blocking member is distinct from the throttle valve, ensuring it doesn't interfere with the engine's speed control.

In practice, the invention can be implemented in several ways. One embodiment uses a plunger within the fuel bowl that directly blocks the fuel nozzle. Another uses a butterfly valve in the gas passageway to block the air/fuel mixture. The actuation can be achieved through Bowden cables, levers, or push-pull knobs, all linked to the blocking member. A single control can simultaneously actuate the fuel shutoff and ground the ignition system, ensuring a complete engine shutdown.

The differentiation from prior approaches lies in the simplicity and mechanical nature of the fuel shutoff. Unlike solenoid-based systems, it doesn't require a battery, reducing cost and complexity. Unlike throttle-based systems, it doesn't interfere with the engine governor, maintaining engine performance. By blocking fuel downstream of the fuel bowl, it minimizes the amount of unburned fuel that can be drawn into the engine after shutdown, reducing emissions and preventing backfiring. The mechanical linkage provides a direct and reliable shutoff mechanism.