The wankel engines, also known as the rotary engines are internal combustion engines that were commonly used in mazda cars.it was invented by a german engineer named felix wankel hence the name. There are two rotors laid 180 degrees apart connected by an eccentric shaft which is an equivalent to a crankshaft in a piston engine. in the wankel casing we have a front plate, first rotor housing, center plate, second rotor housing and the rear plate.
They are not the normal piston cylinder engines instead they are replaced by a triangle shaped rotor rotating in a case and performing the normal four strokes of combustion i.e intake, compression, power, exhaust.
wankel intake stroke
The triangle shaped rotor in the engine rotates clockwise and creates a vacuum hence air/fuel is drawn in the space via the intake port.
Wankel compression stroke
The triangle shaped rotor in the engine rotates clockwise hence pushing the air/fuel mix into a corner hence compressing them at a high ratio.
Wankel power stroke
the triangle shaped rotor rotates again and in this stage a spark is produced by the spark plugs set on the side which catalyzes the rotors clockwise rotation.
Wankel exhaust stroke
The triangle shaped rotor rotates one last time and the exhaust gases are pushed out by the rotating rotor.
As you can note the four strokes are the same its only the construction of the engine that is different. you can save on lubricating and cooling substances because there is less moving parts i.e there are no camshaft, rings, pistons, belts e.t.c hence we can simply say its energy saving.
We can say on the contrary the demerit is that it hard to get or increase compression ratio in this engines hence its not as powerful as the normal piston engine or gas turbine engine.