Back in 1954, the invention of the rotary engine was indeed the headline. The engine differs in the way of mechanism from the regular piston engine. Of course, it did take some effort from Dr Wankel to make it more practical. By 1967, the rotary engines were a commercial success due to Mazda.
Let’s take a look at what sets the rotary engine apart from traditional engines and why it failed to compete against the piston engine.
Understanding 4-stroke Engine
Rotary engines have one thing in common with the piston engine. Both rely on the 4-stroke principle, intake, compression, combustion and exhaust.
When a piston first moves down in a piston engine, it creates a suction that pulls in the air and fuel mixture, known as intake stroke. On the upward motion, the temperature of air-fuel mixture rises followed by ignition from the spark plug. This leads to combustion driving the piston downward. As the piston rises again, the final stroke causes the burnt air-fuel mixture to escape through the exhaust valve.
Understanding Rotary Engine
The rotary engine follows similar steps as in the 4-stroke piston engine but differs in design and mechanism. The rotary engine has no pistons, cylinders or camshaft. Instead, it depends on five key components, rotor, rotor housing, eccentric shaft, front and rear plating.
The rotor is in the shape of a circular triangle that rotates around a fixed gear attached to the housing. The gear ensures the rotor follows a designated circular path. The rotor rotates the eccentric shaft, which is responsible for moving your car wheels.
The rotor housing consists of two openings for intake and exhaust on one side and spark plugs on the other. As the triangle rotates, when the first peak passes through the intake zone, it creates a suction that draws out the air-fuel mixture. As the rotor continues to rotate, it compresses the mixture and triggers the spark.
Since the combustion zone is long, one spark plug is not enough as combustion will be slow to spread. Hence, two spark plugs are used for adequate combustion. This pushes the rotor to continue to rotate and let the burnt gases out from the exhaust port.
The cycle continues for each triangular peak. This results in simultaneous occurrence of intake, combustion and exhaust.
Rotary Engine vs Piston Engine
Looking at the mechanism of both engines, the rotary engine does offer some advantages and disadvantages over the piston engine.
Benefits of Rotary Engine
- Fewer engine components result in cheaper production, compact engine size and reduced weight
- Reduced operational vibrations mean quitter and smoother operation
- Unlike pistons, slower movement of the rotor in one direction improves longevity due to less strain
- Component damage results in loss of power and is less likely to cause catastrophic failure
- Offers higher RPMs range as compared to its weight and size
Drawbacks of Rotary Engine
- Lower thermal efficiency leads to unburnt fuel with an increased tendency to engine backfire
- Rotary housing needs constant lubrication resulting in more burnt oil
- Consumes more fuel while generating less horsepower resulting in poor fuel economy
- Produce more emission as compared to a regular piston engine
Frequently Asked Questions
Why did the rotary engine fail?
Higher emissions were the primary cause of rotary engine failure. Even with a smaller engine and higher horsepower, poor fuel economy was another reason. However, Mazda has confirmed that the rotary engine will make a return by 2022.
Last cars to use rotary engines?
Mazda RX was the last car to use a rotary engine. Due to high emission requirements in Europe, the RX-8 production sale ended by 2010. The production Mazda RX-8 ended in June 2012 as the market sales dropped.
The rotary car engine was known for power and soundless operation. Even with some advantages over the piston engine, the rotary engine would not be able to compete in the market due to various emission regulations and UAE’s green economy initiatives today.
The news of Mazda bringing the engine back might just be the innovation it needs to survive the emission problems. In fact, the upcoming engine is in line to be used as a prototype to test and extend the range of Mazda’s electric car, MX-30.
Since the end of the rotary engines in 2012, piston car engines are a lot more powerful with access to a range of affordable and luxury cars. Explore your options from our list of used cars for sale in the UAE.
Stay tuned to the UAE’s leading auto blogs for more information on car parts, market trends and automotive technology.
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