What is a Single Cylinder Engine?

In this post, we will going to learn what is single cylinder engine and how it works. This article will also go over the working, advantages, and uses.

What is a Single Cylinder Engine?

An engine with only one cylinder is referred to as a single-cylinder engine, or occasionally a thumper. Single-cylinder engines come in both 4-stroke and 2-stroke configurations.

It can generate a comparatively big amount of power considering its size. Unfortunately, the limited power output variation of this engine limits its suitability for larger cars. These types of engines are a wonderful option for machines that run on engines, such weed whackers, because they are small and light.

In addition to motorcycles, they are used in a variety of other applications, including go-karts, all-terrain vehicles, portable equipment, and garden machines. There are many advantages and characteristics to these engines. Here is a detailed discussion about it below.

Characteristics

Single-cylinder engines are typically easier to operate and smaller than multi-cylinder engines. Single-cylinder engines are often more effective at air cooling because there is greater airflow around all sides of the cylinder.

In comparison to liquid-cooled engines, this results in a reduction of both weight and complexity in air-cooled single-cylinder engines.

This engine have higher vibration levels and a more pulsing power output during each cycle. Due to this, single-cylinder engines often have heavier flywheels than multi-cylinder engines, resulting in slower engine speed changes.

Petrol is the most common fuel for single-cylinder engines in motor vehicles. Diesel single-cylinder engines (such as the Lombardini 3LD and 15LD) are used for stationary applications.

Parts of Single Cylinder Engine

The components of a single-cylinder engine that are crucial are as follows:

#1 Cylinder

Typically, a cylinder is composed of cast iron. It has a piston that rotates within the cylinder to carry out combustion.

#2 Piston

A reciprocating device that moves within a cylinder is called a piston. It is usually composed of aluminum alloy. The piston’s other end is fastened to the connecting rod.

#3 Connecting Rod

The piston and crankshaft are connected by the connecting rod, which aids in the combustion pressure transmission to the crankpin. It has bearing components on both ends; the large end is on the crankshaft side, while the smaller end is on the piston side.

#4 Intake and Exhaust Valve

The inlet valve lets new charge to enter the cylinder. It only opens during the suction stroke to receive the air/fuel combination.

The exhaust valve controls the flow of burnt exhaust gasses. It only opens on the exhaust stroke, forcing the burnt air/fuel combination out of the cylinder.

#5 Intake and Exhaust Manifold

Intake manifold allows the cylinder to receive a fresh charge. Multiple-cylinder engines need intake manifolds to evenly transfer charge between the cylinders.

The exhaust manifold is the part of a vehicle’s exhaust system that is directly mounted to the engine block. It releases all exhaust gasses from all cylinders into the atmosphere.

#6 Spark Plug and Fuel Injector

Spark plug is made up of two electrodes separated by an air gap through which a high-tension ignition system discharges, resulting in a spark that ignites the air-fuel mixture. It is commonly seen in petrol engine.

The fuel injector is responsible for supplying fuel to the engine cylinders while monitoring fuel atomization, injection time, and other parameters. It is commonly seen in diesel engine.

#7 Crankshaft and Crankpin

The crankshaft transfers linear motion generated by the engine into rotating motion. It is a revolving shaft with one or more crankpins that are powered by connecting rods and pistons.

#8 Flywheel

The flywheel is a heavy, circular disc-like component that links to the engine’s output shaft. Its major purpose is to provide the engine with smooth functioning by ensuring that the gearbox rotates at a constant speed.

Working of Single Cylinder Engine

Single-cylinder engines can be found in two different configurations: four-stroke and two-stroke.

Single Cylinder 4-Stroke Engine

The petrol engine operates on the principle of otto cycle, often known as the constant volume cycle. In this engine, the spark plug located at the top of the cover ignites the gasoline.

In a four-stroke engine, each cycle consists of two crankshaft revolutions with four strokes: intake, compression, power, and exhaust. Let’s look at how the four-stroke engine works.

#1 Intake Stroke

When the piston reaches top dead center, or TDC, the intake stroke starts. The inlet valve opens when the piston descends. The cylinder is filled with a mixture of air and fuel gases that have been proportionally combined by the carburetor.

Now, the piston has reached its lowest point, known as BDC (bottom dead center).

#2 Compression Stroke

After the intake stroke, the piston rises once again during the compression stroke. When the piston travels upward, the inlet valve closes while the exhaust valve remains closed.

As the piston pushes the air-fuel mixture upward into the clearance space at the top of the cylinder, pressure and temperature increase.

#3 Power Stroke

A spark ignites an air-fuel mixture that is at high pressure and temperature. As a result, the gases are exposed to increased pressure and temperature.

The gasses expand, providing an explosive force that propels the piston downward at tremendous speeds. The crankshaft then rotates as a result of the linear movement of the piston.

#4 Exhaust Stroke

Now, the piston reached its bottom dead center (BDC), releasing the exhaust valve allows the burnt gasses to leave more quickly.

The piston rises from the bottom center and forces remaining burnt gasses into the cylinder. After the exhaust stroke is complete, the exhaust valve closes, and the cycle is started again.

Single Cylinder 2-Stroke Engine

In two-stroke engines, the cycle of operations is completed by one crankshaft revolution or two piston strokes. The otto cycle, also known as the constant volume cycle, controls the operation of two-stroke engines.

#1 First Stroke

During this stroke, the piston is in its BDC position. The piston moves up from BDC to TDC, closing the transfer and exhaust ports. The mixture of air and fuel is present in the cylinder and it is compressed.

As the piston rises, a partial vacuum forms in the crankcase, which allows a fresh charge to be drawn into the crankcase. The piston attains TDC near the end of the stroke.

#2 Second Stroke

During the compression stroke, an electric spark ignites the compressed air-fuel combination in the combustion chamber. The piston moves downward as a result of combustion.

During this stroke, the piston blocks the inlet port and compresses the fresh charge in the crankcase. Both the transfer and exhaust ports open as the piston descends further.

The compressed gases exit through the exhaust port, forcing a fresh charge into the cylinder that has previously undergone compression in the crankcase. This cycle is repeated each time the charge strikes the deflector, and the piston crown rises, pushing the exhaust gases out.

Difference Between 4-Stroke vs 2-Stroke Engine

4-Stroke Engine	2-Stroke Engine
During a power stroke, the crankshaft makes two revolutions.	During a power stroke, the crankshaft makes one revolution.
There is less torque produced by a 4-stroke engine.	A 2-stroke engine produces a lot of torque.
This engine produces improved thermal efficiency.	This engine provide less thermal efficiency.
It is more efficient and produces less smoke.	It is less efficient and produces more smoke.
A four-stroke engine uses less lubricant.	For a two-stroke engine, more lubricant is needed because some of it burns along with the petrol.
There is less wear and tear on this engine.	This engine experiences increased wear and tear as a result of inadequate lubrication.
Because they require lubrication and valves, engines are difficult to produce and are costly.	These are easier to make and cost less to produce.
Because of its heavier and quieter flywheel, these engines are essentially heavier.	Generally, two-stroke engines are louder and lighter.

Advantages of Single Cylinder Engine

Following are the advantages of single cylinder engine:

Typically, these engines are simpler and more compact than multi-cylinder engines.
These engines are usually smaller and easier to operate than multi-cylinder engines. Consequently, when compared to a liquid-cooled engine, it reduces the weight and complexity of an air-cooled engine.
The engine is less expensive to construct because it has fewer components and weighs less.
Single-cylinder engines deliver maximum torque at low rpm, making them ideal for load lagging and torque-intensive applications.
Single-cylinder engines use less gasoline per cubic capacity than twin-cylinder engines.
Since single-cylinder engines have fewer moving parts and a simpler design, maintenance and repair are easier.

Disadvantages of Single Cylinder Engine

Following are the disadvantages of single cylinder engine:

These engines provide greater pulsing power and higher amounts of vibration with each cycle.
A heavy flywheel needed for this engine which causes the engine to change speed rather slowly.
The single-cylinder engine isn’t the smoothest to operate.
A single-cylinder engine produces more torque at low to mid-rpms, but its maximum power output is less than a twin-cylinder engine.
Since the components become too big and heavy for practical usage, they cannot be used in applications that require more cubic capacity.

Applications

In the early days of motorcycles, cars, and other uses including marine engines, single-cylinder engines were widely used. This design is only used on portable equipment and garden gear like lawnmowers.

These engines are also utilized in motor scooters, go-karts, auto rickshaws, and radio-controlled vehicles. From 1921 to 1960, Lanz Bulldog tractors were propelled by single-cylinder two-stroke engines positioned horizontally.

The engine of the Honda Super Cub is a 49 cc single-cylinder, four-stroke motor. There are many single-cylinder sportbikes designed for single-cylinder engines, including dual-sport motorcycles and Royal Enfield 500 Bullets.

Wrapping It Up

That’s it. Thanks for reading. I hope I have covered everything. It would be helpful if you could let me know if there was anything I missed or if you have any doubts about anything I wrote.