Why the RCV is an ideal internal combustion engine

The RCV engine is based around a rotating valve that forms the combustion chamber and controls the gas exchange process. While the valve appears to be a simple component, it is the result of extensive development, being covered by both granted and pending patents.

The RCV Engine operates reliably on gasoline, and on all kerosene based heavy fuels inclding JP5 and JP8. It starts readily, handles well, and is extremely tolerant to changes in air fuel ratio, ignition timing, fuel composition, altitude, and ambient temperature. Heavy fuel operation in particular is a significant challenge for conventional engine technologies.

The root cause of these excellent running characteristics is the RCV Engine’s ideal combustion system.

The combustion system is the means by which the engine mixes air and fuel together, burns it within a combustion chamber, and uses the resultant rise in pressure to produce mechanical power.

An internal combustion engine can be thought of as a series of very short-lived bonfires. The “bonfire” is assembled by mixing air and fuel in the combustion chamber. The mixture is then ignited by the spark plug. The flame front then spreads throughout the chamber until the charge is completely consumed. The heat retained within the charge increases its pressure, which acts upon the piston to perform mechanical work.

For this process to be rapid, reliable and efficient two conditions are essential.

Firstly, the fuel and air must be thoroughly mixed: in the bonfire analogy the wood must be split into small pieces and uniformly stacked with air gaps in between.

Secondly the combustion chamber must be a compact shape: in the bonfire analogy the wood must be stacked in a compact shape rather than spread over a large area.

The RCV rotating valve fulfils both ideal characteristics.

The rotation of the valve generates a high level of turbulence which mixes the fuel and air thoroughly. The combustion chamber within the rotating valve body is very compact. This ensures the burn spreads reliably and rapidly from the ignition point through the entire charge, and that as much heat as possible is retained within the charge to produce mechanical work. As a result the RCV is easy starting, powerful, and reliable on both gasoline and HF.

RCV Technology Key Characteristics

  • Four-stroke cycle for low emissions and fuel consumptions
  • Excellent starting over a wide temperature range -20°C to +40°C
  • Ideal compact combustion system with no hot-spots
    • Turn-key heavy fuel operation
    • Stable response to changes in AFR or ignition timing
    • Insensitive to changes in fuel quality or altitude
    • Resistant to detonation and carbon build up
  • Large valve breathing area gives high power with a wide power band
  • High reliability, low maintenance with long MTBO:
    • No injectors in the combustion chamber to carbon up
    • No valve clearances to adjust
    • Shielded spark plug for minimum plug fouling and long life
  • Designed as a UAV engine not modified from a hobby engine
  • Electronic fuel injection system with altitude compensation
  • Dedicated mounting system for 100 W to 3 kW alternators
  • Available in air cooled and liquid cooled versions

The RCV engine incorporates a conventional crank and piston.

The rotating valve is situated above the piston and is driven from the crank at half engine speed. The inlet port, spark plug port and exhaust port are arranged radially around the valve.

As the engine rotates through 720 degrees the combustion chamber in the valve communicates successively with the inlet port, the spark plug, and the exhaust port. The RCV engine is thus operating on a conventional 4 stroke cycle.

A visualisation of the combustion event in an RCV engine is shown below

A visualisation of the RCV engine operating cycle is shown below.

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