The rotary engine got its start in pre-World War II Germany thanks to the innovations of Dr. Felix Wankel, who received his first patent in 1936 and later interested NSU, a German motorcycle manufacturer, in the technology that serves as the basis for all rotary engines today — including the Mazda Renesis powering the RX-8 sports coupe.
While rotary engines haven’t revved up the powersports industry in decades, one company, RotaMax, is attempting to bring back interest among powersports manufacturers.
Eric Barger, RotaMax president, thinks rotary engines are highly suited for powersports and, as far as he knows, no powersports manufacturer is using them. To drum up interest, Barger and others from the company attended the Indy Dealer Expo for the first time in February.
“There’s 2,500 patents that have expired relating to rotary engines, so it’s an open technology,” Barger said. “There are great opportunities to expand beyond our current engine program. Open means opportunity.”
Barger and three partners started Ohio-based RotaMax in 2001 under the name Thermo Fan. The group was originally trying to develop a product that could heat and cool semi-trailer truck sleepers when they are parked without idling. In the process of refining that idea came rotary technology. Realizing rotary engines had the potential to fit in dozens of markets, Barger opted to save the heating and cooling idea for later and work on developing RotaMax. The company acquired a license to manufacture and distribute rotary engines in the United States and Canada.
RotaMax currently creates rotary engines for hovercraft, concrete saws and hybrids. It plans to start testing a military project and is in talks with an undisclosed major boat supplier. RotaMax offers a 650cc (or 85 horsepower) model and a 1,300cc (or 175 horsepower) model, and is developing a 150cc (or 20-25 horsepower) model.
How it works
Most people are familiar with piston engines. The pistons go up and down, taking in and compressing, combusting and exhausting fuel and air all within the same space. Many people are not familiar with rotary engines, which do all four of the aforementioned in individual compartments.
A rotary engine has an oval-shaped housing and a triangular rotor. Like a Spirograph, the rotor rotates on an output shaft that has round lobes offset from the centerline of the shaft. Metal blades on the rotor’s corners and metal rings on its sides create sealed chambers between the housing and the rotor. The engine is designed so the tips of the rotor are always in contact with the housing wall. The volume in these chambers expands and contracts as the rotor moves.
When a tip of the rotor passes the intake port, the chamber’s volume is at a minimum, but the volume expands as the rotor moves, drawing in an air/fuel combination. When the rotor tip passes the intake port, the chamber is sealed and compression begins.
The volume of the chamber gets smaller and the air/fuel mixture gets compressed. Enter the spark plugs for some combustion when the chamber’s volume is again close to minimum.
Most rotary engines have two spark plugs because the combustion chamber is too long for just one. The pressure of combustion makes the rotor move in the direction in which the chamber’s volume will grow. The gases continue to expand, moving the rotor and creating power until the rotor’s tip passes the exhaust port. Once that happens, gases flow out the exhaust. By the time the volume of the chamber is near minimum, the rotor tip passes over the intake port and the cycle starts over again.
The benefits of a rotary engine are fewer moving parts than piston engines, which can mean more reliability and easier service, Barger said. He said rotary engines also run more smoothly since all the parts spin continuously in one direction, and which also makes the power delivery smoother and cuts down on vibrations.
“It’s simple, has a high power to weight ratio, is multi-fuel capable and vibration free,” Barger said.
Barger said he has ideas for all kinds of applications for rotary engines, and hopes to establish the company as an engine supplier in the powersports, agricultural, recreational and industrial industries. If that plan proves successful, RotaMax will look into what markets it can build a product for. He hopes to eventually offer a line of engines ranging from five to 500 horsepower.
Copyright 2006 Powersports Business