A large metal wheel-like device called a flywheel is attached to one end of the crankshaft, which works to keep its motion constant. This is necessary in a four-stroke engine because the pistons perform a power stroke only once for every four strokes. A flywheel provides the momentum to carry the crankshaft through its movement until it receives the next stroke of power. To do this, it uses inertia, that is, the principle that an object in action will tend to remain in motion. Once the flywheel is set in motion by turning the crankshaft, the crankshaft will continue to move and will turn the crankshaft. However, the more cylinders an engine has, the less it will need to depend on the movement of a flywheel because more pistons will keep the crankshaft turning.
Once the crankshaft is turning its movement can be adapted to a wide variety of uses, thus fitting gears, belts or other devices. With which, both the wheels, the propellers or the motor can be turned, thus it can be used simply to generate electricity.
How an internal combustion engine works
Today we explain how an internal combustion engine works. The vast majority of vehicles (passenger cars and commercial vehicles) sold today are equipped with internal combustion engines. In this article that turbo3 offers you, we explain how it works.
Internal combustion engines generally employ reciprocating motion, although gas turbine, rocket, and rotary engines are examples of other types of internal combustion engines. However, reciprocating internal combustion engines are the most common and found in most cars, trucks, motorcycles, and other engine-powered machines.
The most basic components of the internal combustion engine are the cylinder, piston, and crankshaft. To these are attached other components that increase the efficiency of the reciprocating motion and make it the rotary motion of the crankshaft. Fuel must be provided in the cylinder and the exhaust, formed by the explosion of the fuel, and must have an outlet from the cylinder in addition to the ignition of the fuel. In the reciprocating internal combustion engine, this is done in two ways.
Diesel engines
Diesel engines are also called compression engines because they use compression to make the fuel ignite automatically. The air is compressed, that is, it is pushed into a small space in the cylinder. Compression causes the air to heat up, so when fuel is introduced into hot compressed air, the fuel explodes. The pressure created by compression requires diesel engines to be stronger and therefore heavier than gasoline engines, yet they are more powerful and require less expensive fuel. Diesel engines are generally found in large vehicles such as trucks and heavy construction equipment or stationary machines.
Gasoline engines
Gasoline engines are also called positive ignition engines because they rely on a spark of electricity to cause fuel to explode inside the cylinder. Lighter than a diesel engine, the gasoline engine requires a more refined fuel.
In an engine, the cylinder is housed within an engine block strong enough to contain fuel explosions. Inside the cylinder is a piston that fits precisely into it. Pistons are generally domed at the top and hollow at the bottom. The piston is connected to a crankshaft through a connecting rod placed in the hollow bottom that converts the up and down movement of the piston into a circular movement. This is possible because the crankshaft is not straight, but rather has a bent section (one for each cylinder) called the crank.
Intake blow
A similar structure powers a bicycle. When riding a bicycle, the upper part of a person’s leg is similar to the piston. From the knee to the foot, the leg acts as a connecting rod that is attached to the crankshaft by the crank or pedal assembly of the bicycle. These parts are made to move when energy is applied to the upper leg. Whereupon, the reciprocating motion of the lower leg becomes the rotary or rotary motion of the crankshaft.
Note that when riding a bike, the leg performs two movements: one downward and one upward to complete the pedaling cycle, which are called strokes. Because an engine also needs to extract fuel and expel it again, most engines use four strokes for each cycle the piston performs. The first stroke begins when the piston is at the top of the cylinder, called the cylinder head. As it is drawn out, it creates a vacuum in the cylinder. This is because the piston and cylinder form an airtight space. When the piston is pulled down, the space between it and the cylinder head is enlarged, while the amount of air remains the same. This vacuum helps draw fuel into the cylinder, as does the action of the lungs. Therefore, this blow is called an intake blow.
Compression stroke
The next stroke, called the compression stroke, occurs when the piston is pushed up back into the cylinder, squeezing or compressing the fuel into an increasingly narrow space. Compressing the fuel against the top of the cylinder causes the air to heat up, which also heats the fuel. Compressing the fuel also makes ignition easier and makes the resulting explosion more powerful. There is less room for the expanding gases from the explosion to flow, which means they will push harder against the piston to escape.
At the top of the compression stroke the fuel ignites, causing an explosion that pushes the piston down. This stroke is called the power stroke and it is the stroke that turns the crankshaft.
The final stroke, that is, the exhaust stroke, brings the piston up again, expelling the exhaust gases created by the cylinder explosion through an exhaust valve. These four strokes are also commonly referred to as “suck, squeeze, hit, and blow.”
Two-stroke engines
Two-stroke engines eliminate intake and exhaust strokes, combining them with compression and power strokes. This allows for a lighter and more powerful engine, relative to the engine size, which requires a less complex design. But the two-stroke cycle is a less efficient method of burning fuel. An unburned fuel residue remains inside the cylinder, preventing combustion. The two-stroke engine also fires its fuel twice as often as a four-stroke engine, increasing wear on engine parts. Therefore, two-stroke engines are mainly used when a smaller engine is required, such as on some motorcycles and with small tools.
Combustion requires the presence of oxygen, so the fuel must be mixed with air to ignite.
How is combustion generated?
Diesel engines feed fuel directly to react with hot air inside the cylinder. Spark ignition engines, however, first mix the fuel with air outside the cylinder. This is done via a carburetor or via a fuel injection system. Both devices vaporize gasoline and mix it with air in a ratio of about 14 parts of air to every part of gasoline. A choke valve on the carburetor controls the amount of air that mixes with the fuel, and at the other end, a throttle valve controls the amount of fuel mixture that will be sent to the cylinder.
The vacuum created when the piston moves down through the cylinder pushes the fuel into the cylinder. The piston must fit precisely inside the cylinder to create this vacuum. Rubber compression rings placed in piston grooves ensure a tight fit. Gasoline enters the cylinder through an intake valve. The gasoline is then compressed in the cylinder by the next movement of the piston while waiting for ignition.
Cylinders
The timing of the firing of the cylinders is controlled by the distributor. When current enters the distributor, it is routed to the spark plugs through wires, one for each spark plug. Mechanical distributors are essentially rotating rotors that send current to each wire one at a time. Likewise, electronic ignition systems use computer components to accomplish this task.
Piston
Smaller engines use a battery that, when it runs out, is simply replaced. Most engines, however, have provisions for recharging the battery, using the movement of the rotating crankshaft to generate return current.
The piston or pistons push down and up the crankshaft causing it to rotate. This conversion from the reciprocating movement of the piston to the rotary movement of the crankshaft is possible because for each piston of the crankshaft has a crank, that is, a section that forms an angle with the up and down movement of the position. On a crankshaft with two or more cylinders these cranks are also set at angles to each other, allowing them to act together. When one piston pushes its crank down, a second crank pushes its piston up.
The steering wheel
A large metal wheel-like device called a flywheel is attached to one end of the crankshaft, which works to keep the crankshaft motion constant. This is necessary in a four-stroke engine because the pistons perform a power stroke only once for every four strokes. A flywheel provides the momentum to carry the crankshaft through its movement until it receives the next stroke of power. To do this, it uses inertia, that is, the principle that a moving object will tend to stay in motion. Once the flywheel is set in motion turning the crankshaft will continue to move and will turn the crankshaft. However, the more cylinders an engine has, the less it will need to depend on the movement of a flywheel as more pistons will keep the crankshaft turning.
Once the crankshaft is turning, its movement can be adapted to a wide variety of uses, thus fitting gears, belts or other devices. With which, you can make both the wheels turn, as the propellers or the motor to generate electricity.
Camshaft
Additionally, attached to the crankshaft is an additional shaft, called a camshaft, which operates to open and close the intake and exhaust valves of each cylinder in sequence with the four-stroke cycle of the pistons. A cam is a wheel that is roughly egg-shaped, with a long end and a short end. Several cams are attached to the camshaft, depending on the number of cylinders the engine has. At the top of the cams are pushrods, two for each cylinder, which open and close the valves. As the camshaft rotates, the short ends allow the push rods to be removed from the valve. In this way, it causes the valve to open, the long ends of the cams push the rods towards the valve closing it again. In some engines, called camshaft engines, the camshaft rests directly on the valves, thus eliminating the need for the pushrod assembly. Two-stroke engines, because intake and exhaust are achieved by moving the piston over ports or holes in the cylinder wall, do not require the camshaft.
Crankshaft
The crankshaft can drive two more components: the cooling and lubrication systems. The fuel explosion creates intense heat that would quickly cause the engine to overheat and even melt if not dissipated or removed properly. Cooling is accomplished in two ways: through a cooling system and, to a lesser extent, through the lubrication system.
There are two types of cooling systems. A liquid cooling system uses water, which is often mixed with an antifreeze to prevent freezing. Antifreeze lowers the freezing point and also increases the boiling point of water. Water, which is very good at accumulating heat, is pumped around the engine through a series of passageways contained in a jacket. The water then circulates to a radiator, which contains many tubes and thin metal plates that increase the surface of the water. A fan attached to the radiator blows air over the pipe, further lowering the water temperature. Both the pump and the fan are operated by the movement of the crankshaft.
Refrigeration systems
Air-cooled systems use air-cooled air, instead of water, to extract heat from the engine. Most motorcycles, many small airplanes, and other machines where a large amount of wind is produced by their movement use air-cooled systems. In these, the metal fins are attached to the outside of the cylinders, creating a large surface area. As the air passes over the fins, the air carries the heat conducted to the metal fins from the cylinder.
Lubrication
The lubrication of an engine is vital for its operation. Movement of parts against each other causes great friction, which increases heat and causes parts to wear out. Lubricants, like oil, provide a thin layer between moving parts. The passage of oil through the engine also helps to remove some of the heat produced.
The crankshaft at the bottom of the engine rests in a crankcase. This can be filled with oil, or a separate oil pan under the crankcase serves as a reservoir for the oil. A pump carries the oil through passages and holes to the different parts of the engine. The piston is also equipped with rubber oil rings, in addition to compression rings, to carry the oil up and down the inside of the cylinder. Two-stroke engines use oil as part of their fuel mixture, which provides lubrication to the engine and eliminates the need for a separate system.
Internal combustion engine
An internal combustion engine can have between one and twelve or more cylinders, all acting together in a precisely timed sequence to drive the crankshaft. The rider on a bicycle can be described as a two-cylinder engine, each leg helping the other to create the power to propel the bike and to pull each other through the racing cycle. Cars generally have four-, six-, or eight-cylinder engines, although two- and twelve-cylinder engines are also available. The number of cylinders affects the engine displacement, that is, the total volume of fuel that passes through the cylinders. A larger displacement allows more fuel to be burned, creating more energy to drive the crankshaft.
The spark is introduced through a spark plug located in the cylinder head. The spark causes the gasoline to explode. Spark plugs contain two metal ends, called electrodes, that extend into the cylinder. Each cylinder has its own spark plug. When electrical current passes through the spark plug, current jumps from one electrode to another, creating the spark.
This electrical current originates from a battery, however the current from the battery is not strong enough to create the necessary spark to ignite the fuel. Therefore, it is passed through a transformer, which greatly amplifies its voltage or strength. Then the current can be sent to the spark plug.
However, in the case of an engine with two or more cylinders, the spark must be directed to each cylinder in turn. The firing sequence of the cylinders should be timed so that while one piston is on its power stroke, another piston is on its compression stroke. In this way, the force exerted on the crankshaft can be kept constant, allowing the engine to run smoothly. The number of cylinders affects the smoothness of the engine’s operation. Thus, the more cylinders, the more constant the force on the crankshaft and the smoother the engine will run.
