The eventual demise of the internal combustion engine seems inevitable to this day. With the increasing development of electric powertrains and battery technology advancing at lightning speed in recent years, developing, building and ultimately owning an electric motorcycle is now cheaper and seems inevitable in the future. But an American company, Astron Aerospace, is working on a new patent-pending rotary engine concept that promises to combine the advantages of turbine and piston engines for even greater efficiency and reduced pollutant emissions.
That being said, the internal combustion engine will certainly be present for several more years, even after the ban proclaimed in 2035 on the sale of vehicles equipped with this engine. Several companies, including some motorcycle and car manufacturers, have lobbied to keep gasoline engines in existence. This is also the vision of Astron Aerospace with its latest creation, the Omega 1.
Astron Aerospace's Omega One rotary engine is a 4-stroke engine, as in conventional piston engines, but promises to improve torque and simplify emissions control while retaining the advantages of the turbine such as cooling by air, the low number of parts and the compact size. The Omega 1 is mainly intended for aviation, but a range extension application for electric vehicles is currently being co-developed. It notably integrates homogeneous charge compression ignition (HCCI).
This is all well and good, but how does it work? What Astron did was separate the four strokes of an internal combustion engine into two separate chambers with a pre-chamber in between. The engine therefore consists of two main shafts stacked vertically and connected to synchronizing gears so that they rotate at the same speed in opposite directions. Four rotors spin on the two shafts in two pairs, one pair stacked at the front which includes the intake and compression stages, the other pair at the rear relating to combustion and exhaust. Between the two sets of rotors is a rotating disc valve and a pre-chamber.
The compression area is about a third larger, allowing it to "supercharge" the combustion chamber via a small air storage tank that sits between these pairs of rotors. The purge valves regulate the inlet pressure, located between 12 and 22 bars.
The two lower rotors both have a vane operating in their own chamber, and the two upper rotors are solid except for a notch that meshes with the vanes of the lower rotors. Air is introduced into the front end chamber in front of the vane, and as it rotates, the vane compresses the air as it collides with the upper solid rotor. When the top rotor notch is exposed, a port in the side of the chamber opens, allowing compressed air to flow into the prechamber. The paddle engages in the notch, then the cycle begins again.
Meanwhile, in the pre-chamber, fuel is introduced via an injector which delivers a stratified charge at low rpm or a homogeneous charge at higher rpm. The mixture is then allowed into the rear chamber through the rotary valve, and a pair of glow plugs ignite the mixture. The resulting flame propels the vane onto the rear lower rotor until the exhaust port is exposed and the burned gases are expelled from the rear chamber.
HCCI flash combustion, possible up to 10 rpm, and the small combustion chamber area should reduce the engine's NOx emissions enough to eliminate the three-way catalyst, which does not work with a excess air.
The result is a motor with no reciprocating parts, and Astron claims that with precise machining, no sealing issues like those encountered in a Wankel-type rotary motor.
According to simulations carried out by Astron Aerospace, this engine weighs 15 kg and produces a power of up to 160 hp, reaching 80% thermal efficiency, no less! It idles at 1000 rpm and the red zone is around 25 rpm.
These are Astron Aerospace's claims. But enough people saw enough merit in the concept to fully fund the company within days.
Astron Aerospace has not explicitly stated that this engine is intended for motorcycles. However, given its theoretical versatility, it could certainly power two-wheelers if mass-produced. Astron Aeropsace has announced that the company has created a working prototype and claims that it can run on a wide variety of fuels, producing very low emissions.
