WANKEL ENGINET.HARISH11951A2163The figure below shows an overview of wankel engine and all its major parts are included

CONSTRUCTION

Parts of Wankel engine1.INTAKE PORT2. EXHAUST PORT3. OVAL CHAMBER4. CHAMBER VOLUME5. SHAFT GEARING6. ROTOR7. SHAFT LOBE8.ECCENTRIC SHAFT9. SPARK PLUG

While a four-stroke piston engine makes one combustion stroke per cylinder for every two rotations of the crankshaft (that is, one half power stroke per crankshaft rotation per cylinder), each combustion chamber in the Wankel generates one combustion stroke per each driveshaft rotation, i.e. one power stroke per rotor orbital revolution and three power strokes per rotor rotation. Thus, power output of a Wankel engine is generally higher than that of a four-stroke piston engine of similar engine displacement in a similar state of tune; and higher than that of a four-stroke piston engine of similar physical dimensions and weight.

WORKINGThe Wankel engine works on the Otto cycle as does the reciprocating piston engine.The three-lobe rotor makes three spaces around it in the oval chamber. The four cycles of intake, compression, power and exhaust go on simultaneously in the three spaces around the rotor when the engine is running.

Intake: The figure represents fuel intake, in which the rotor side creates suction. The fuel mixture from the carburetor enters the suction chamber.Compression: As the rotor turns clockwise, the mixture is compressed between the rotor and the chamber. In this stage the air-fuel mixture is compressed to that extent which would be enough for combustion.Power: Further, the compressed mixture is ignited by the supply of electric spark from a spark plug. This increases the temperature of mixture and due to the intense heat and pressure of the burnt gases, the rotor moves further clockwise.Exhaust: Finally, the exhaust gases are pushed out of the oval combustion chamber.

There are three power impulses in every revolution of the rotor, which is three times compared to a two-stroke engine and six times compared to a four-stroke engine. The engine delivers power almost continuously. The eccentric motion of the rotor develops vibrations which are eliminated by the use of two symmetrically mounted flywheels.

COMPARISON WITH RECIPROCATING ENGINE

The figure shows all the four strokes of cycle for both reciprocating piston engine and rotary wankel engine

ADVANTAGES OVER RECIPROCATING ENGINEThe wankel engine offers the following advantages over reciprocating engine:smaller in size, lighter in weight and more compact .cheaper and simpler in construction for mass production due to the absence of many working parts like connecting rod, crank shaft, valve mechanism, etc.balancing is easier because it does not contain any reciprocating parts. volumetric efficiency is very high, often exceeding 100%. power output per kg. of engine is considerably higher. running cost is less. does not require overdrive because its speed is very high.

DISADVANTAGESWankel engine is also has certain disadvantage as compared to reciprocating engineHigher fuel consumption for low speed ranges.Higher oil consumption per B.H.P Lower torque speeds.Braking effect of the engine is far less.Reduction of speed in transmission is necessary due to very high engine speed.Due to the ignition troubles experienced with ordinary ignition systems, the spark plug has to be changed frequently. However, this has been remedied by using transistorized ignition.The main obstacle in the development of wankel rotary engine was the sealing problem, which have been largely overcome by now.Cylinder distortion may occur due to the close proximity of inlet and exhaust ports.Very high exhaust gas temperatures, nearly 1600 F, creates problem in exhaust manifold and silencer designs.APPLICATIONSSince its invention, wankel engine has seen vast applications in many fields both in automobile and non automobile applications. Some of the accepted ones are inAUTOMOBILE INDUSTRY:Mazda 787B racing carMazda RX7Norton commander bikeSuzuki RE5

AIR CRAFT INDUSTRY:Diamond DA20Lock heed Q star civilian aircraftSchweizer sailplaneMoller sky car M400UEL UAV 741 Diamond DA20 aircraftOTHER APPLICATIONS: go kartspersonal watercraftsauxiliary power units

CONCLUSIONFinally, I conclude that wankel engine is appropriate when applied for high power requirements where efficiency and economy is not of priority.

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