Advantages of Rotary Engine in Vehicles

Felix Wankel started the development of the rotary engine in early1950s, subsequently completing a working prototype in 1957 afterreceiving the patent for the engine in 1929 (Karwatka 2015, 8). Infact, Felix Wankel conceived the idea of a rotary engine, althoughlater developments adopted and altered the design. The engine is aninternal ignition engine that utilizes an unconventional rotarydesign to convert compression into rotating motion (Alexandru andBuzbuchi 2014, 93). As opposed to the standard piston engine, whichhas pistons that moves in all directions, the rotary engine has allits components moving in one direction. Therefore, the simplicity ofthe engine has seen it used in motorcycles and cars. The engine’srotor coverings are continually heated on one side andair-conditioned on the other side, which leads to high temperaturesand imbalanced thermal expansion eventually placing high demand onthe used materials. However, the simplicity of the engine makes iteasier to use alternative materials such as ceramics and alloys.Today, Mazda has been very effective and successful in enhancing theefficiency and performance of the engine, which has allowed thecompany to produce several models of the engine especially sportscars. In this regards, it is essential to look at the advantages ofthe rotary engine and draw a parallel insight into the arguments forthe advantages of the engine.


The moving parts of the engine move in a constant and unidirectionalmotion, which gives the engine eased balance and lack of vibration.The engine turns in smooth motions and coupled with the lack of avalve acting mechanism allows the engine to generate significantlyless vibration and quite, smooth operation (Al-Hawaj 2015, 118). Inaddition, the constant and unidirectional motion of the movingcomponents means that the engine moves at higher operating speedsthan standard piston engines. The engine also achieves the smoothoperation through the lack of reciprocating components such asconventional crankshaft and connecting rods (Alexandru and Buzbuchi2014, 96). The high operating speeds means that engine yields twiceas much power as an interchanging engine of the same load. Inaddition, the engine has considerably fewer components and occupiesless volume than a reciprocating engine of similar power. In thisregards, the reduced weight and size remains the most substantialadvantages of the engine. In fact, firms can design a rotary engineto be around two-thirds of the size and weight of a normal enginewhile attaining the same output as well as more quietness andsmoothness in operation (Ferguson and Kirkpatrick 2015, 33). Theadvantage is overly attractive to carmakers designers especially interms of weight distribution, collision safety, and space utility.

Numerous studies support the findings that the rotary engine has lownoise and vibration levels (Alexandru and Buzbuchi 2014, 96). Theengine has three power thumps for each cycle of the eccentricproduction shaft, which allows the engine to have low-torqueoscillation and vibration. The three power thumps or pulses for eachrotor cycle and the slow rotor speed allows more time for mixing. Inaddition, the rotation of the shaft means that the engine slows fuelslowly giving it less mechanical noise, although this depends on thecalibration of the engine. The engine has a few overall stress pointsand positive net turning through the chute, which makes the enginereliable and flexible (Cipollone and Battista 2015, 157). Thefour-stroke cylinder in a piston engine yields a power stroke onlyfor each turning of the crankshaft thus, it doubles the realsurface-to-volume ratio, which gives the rotary engine a highervolumetric efficiency and lower propelling losses through the lack ofa valve. In addition, the smooth operation allows the rotary engineto react swiftly to power.

Ferguson and Kirkpatrick (2015) note that the rotary engine has asimple structure, which ensures that the engine counteracts theimbalanced thermal expansion (128). The engine unlike a standardpiston engine does not require a valve mechanism, which containscamshaft, valve, timing belt, and rocker arm thus, has few partsmaking its structure simple. Since the engine changes the expansionpressure of the burnt blend straight into the turning force of thetrilateral propeller and the unconventional shaft, it does notrequire a connecting rod. The simple structure means that the enginelacks valve trains and valves, has less volume occupation, and islightweight especially due to existence of few parts (Al-Hawaj 2015,120). The absence of the valves also enhances safety in the engine.The simple structure of the engine means that engine is cheap todesign and produce thus, low manufacturing costs. In this regards,the lack of a connecting rod and the valve mechanism means that therotary engine can be built with few parts.


Despite the various advantages of the rotary engine, several studieshave shown that the engine has major drawbacks, which limit its usein dominance in the automotive industry. The engine scores lowly infuel economy especially when compared to reciprocating engines, whichoffers great potential in fuel economies, which has made the engineinefficient (Chen et al. 2015, 21). In addition, the engine does nothave a great potential in emissions reduction, which has limited itssuccess in the automotive industry as well as increased themaintenance and overhaul. In this regards, the engine has high fuelconsumption and high emissions of carbon monoxide especially in naïvedesigns. However, some companies such as Mazda have improved the fuelconsumption and carbon monoxide emissions of the engine significantlyespecially for gasoline-fueled engines (Cipollone and Battista 2015,160). In addition, with enough research especially studies aligned toheavy-fueled engines, opportunities exist to enhance the performanceand efficiency of the engines. Carmakers can attain enhancedperformance and efficiency by implementing advanced ignition systems,system optimization, fuel systems, and control systems (Zoia 2010,6). In addition, opportunities in enhancing efficiency exists withenhanced combustion and reduced cooling and friction losses.


Despite its low utilization in vehicles, the rotary engine hasnumerous benefits such as simple structure, smooth operation, lowvibration and noise, as well as low weight and high operating speeds.Most important is that the engine’s simple structure reduces itsweight and gives it a compact nature with few parts, which makes theengine operates smoothly (Zoia 2010, 6). In addition, the simplestructure and lack of valves give the engine high collision safetiesand enhance the combustion process. In addition, the engine hastougher flows of air-fuel mixture and lengthier working cycles, whichgives it a homogeneous mixture. As stated earlier, the engine’sdesign gives it numerous advantages although more research isrequired to enhance its efficiency and performance especially invehicles.


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Chen,Hu, Cunyun Pan, Xiaojun Xu, Xiang Zhang, and Haijun Xu. 2015.Development of Rotary Piston Engine Worldwide.

Cipollone,Roberto, and Davide Di Battista. 2015. “Sliding vane rotary pump inengine cooling system for automotive sector.”&nbspAppliedThermal Engineering 76: 157-166.

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