|The basic element of the IDR engine is two intermeshing rotors. Click to enlarge.|
A South African inventor has developed a new engine concept—the Intermeshing Differential Rotors (IDR) engine—intended to provide a better power-to-mass ratio, improved efficiency, reduced manufacturing cost and durability than current engines. The company commercializing the concept, IDR-Technology, introduced the IDR engine at the 2008 SAE World Congress last month in Detroit, where it won an AEI Tech Award.
The engine is based on two rotors that intermesh but turn at different speeds and alter the speed ratio between them. The rotors alternately drive the engine, with the combustion chamber forming between the intermeshing arms of the two rotors.
The rotor with the biggest leverage on the other rotor will drive the engine or part of a revolution (both rotors will turn). Then the other rotor will have the advantage and turn both rotors.
Combustion occurs every time the rotors exchange angular velocity ratios. The change in roles occurs 12 times per engine revolution—each rotor driving 6 times—producing 12 combustion events. Combustions occur every 30 degrees of outward axle movement, giving IDR technology its high power-to-mass ratio.
The IDR engine has a 3-stage compression and 3-stage expansion cycle. The distance between the two parallel axles of the rotors corresponds to the stroke of a piston engine. The closer they are the greater the “stroke” and the more volume is swept.
The height of the rotors corresponds to the diameter of a piston in a piston engine. The longer the rotors are axially the greater the swept volume will be for a specific axle separation.
High compression ratios of up to 25:1 are possible, and variable intake and exhaust displacement volumes can be created by changing the outer housing shape and position. Multistage compression and expansion cycles can improve efficiencies.
The company, which is filing forpatents on the IDR technology, is seeking early-stage investment.
Animation of the IDR engine.