- Definition and general features
- History of creation
- ICE types
- ICE device
- Internal combustion engine auxiliary systems
- Engine cycles
- ICE advantages and disadvantages
The internal combustion engine has been used in motorcycles, cars and trucks for a century. Until now, it remains the most economical type of motor. But for many, the principle of operation and the device of the internal combustion engine remains unclear. Let's try to understand the main intricacies and specifics of the structure of the motor.
Definition and general features
A key feature of any internal combustion engine is the ignition of a combustible mixture directly in its working chamber, and not in external media. At the moment of fuel combustion, the thermal energy received provokes the operation of the mechanical components of the engine.
History of creation
Before the advent of internal combustion engines, self-propelled vehicles were equipped with external combustion engines. Such units operated from the steam pressure generated by heating water in a separate tank.
The design of such engines was large and ineffective - in addition to the large weight of the installation, to overcome long distances, the transport also had to pull a decent supply of fuel (coal or firewood).
In view of this shortcoming, engineers and inventors tried to solve an important question: how to combine the fuel with the body of the power unit. By removing elements such as a boiler, water tank, condenser, evaporator, pump, etc. from the system. it was possible to significantly reduce the weight of the motor.
The creation of an internal combustion engine in the form familiar to a modern motorist took place gradually. Here are the main milestones that led to the emergence of the modern ICE:
- 1791 John Barber invents the gas turbine, which operates by distilling oil, coal and wood in retorts. The resulting gas, together with air, was pumped into the combustion chamber by a compressor. The formed hot gas under pressure was supplied to the impeller of the impeller and rotated it.
- 1794 Robert Street patents a liquid fuel engine.
- 1799. Philippe Le Bon as a result of the pyrolysis of oil gets luminescent gas. In 1801 he proposes to use it as a fuel for gas engines.
- 1807 François Isaac de Rivaz - patent on "the use of explosive materials as a source of energy in engines." Creates a self-propelled crew based on the development.
- 1860 Etienne Lenoir pioneered early inventions by creating a workable motor powered by a mixture of lighting gas and air. The mechanism was set in motion with a spark from an external power source. The invention was used on boats, but was not installed on self-propelled vehicles.
- 1861 Alphonse Bo de Rocha reveals the importance of compressing fuel before igniting it, which served to create a theory of the operation of a four-stroke internal combustion engine (intake, compression, combustion with expansion and release).
- 1877 Nikolaus Otto creates the first 12 hp four-stroke internal combustion engine.
- 1879 Karl Benz patents the two-stroke motor.
- 1880s. Ogneslav Kostrovich, Wilhelm Maybach and Gottlieb Daimler are simultaneously developing carburetor modifications of the internal combustion engine, preparing them for mass production.
In addition to gasoline-fueled engines, the Trinkler Motor appeared in 1899. This invention is another type of internal combustion engine (non-compressor high pressure oil engine), operating on the principle of the invention of Rudolf Diesel. Over the years, power units, both gasoline and diesel, have improved, which increased their efficiency.
By the type of design and the specifics of the operation of the internal combustion engine, they are classified according to several criteria:
- By the type of fuel used - diesel, gasoline, gas.
- According to the principle of cooling - liquid and air.
- Depending on the arrangement of the cylinders - in-line and V-shaped.
- According to the method of preparation of the fuel mixture - carburetor, gas and injection (mixtures are formed in the outer part of the internal combustion engine) and diesel (in the inner part).
- According to the principle of ignition of the fuel mixture - with forced ignition and with self-ignition (typical for diesel units).
Motors are also distinguished by design and work efficiency:
- Piston, in which the working chamber is located in the cylinders. It is worth considering that such internal combustion engines are divided into several subspecies:
- carburetor (the carburetor is responsible for creating an enriched working mixture);
- injection (the mixture is supplied directly to the intake manifold through the nozzles);
- diesel (the mixture is ignited due to the creation of high pressure inside the chamber).
- Rotary-piston, characterized by the conversion of thermal energy into mechanical energy due to the rotation of the rotor along with the profile. The work of the rotor, the movement of which resembles an 8-ku in shape, completely replaces the functions of the pistons, timing and crankshaft.
- Gas turbine, in which the motor is driven by thermal energy obtained by rotating a rotor with blades resembling a blade. It drives the turbine shaft.
The theory, at first glance, seems clear. Now let's look at the main components of the powertrain.
The body design includes the following components:
- cylinder block;
- crank mechanism;
- gas distribution mechanism;
- systems of supply and ignition of a combustible mixture and removal of combustion products (exhaust gases).
To understand the location of each component, consider the motor structure diagram:
The number 6 indicates where the cylinder is located. It is one of the key components of the internal combustion engine. Inside the cylinder there is a piston marked with 7. It is fastened to the connecting rod and crankshaft (in the diagram, they are designated by numbers 9 and 12, respectively). Moving the piston up and down inside the cylinder provokes the formation of rotational movements of the crankshaft. A flywheel is provided at the end of the tiller, shown in the diagram under the number 10. It is necessary for uniform rotation of the shaft. The upper part of the cylinder is equipped with a dense head, which has valves for the mixture intake and exhaust gases. They are shown under number 5.
The opening of the valves becomes possible due to the cams of the camshaft, indicated by the number 14, or rather, by its transmission elements (number 15). The camshaft rotation is provided by the crankshaft gears, designated by number 13. With free movement of the piston in the cylinder, it is able to take two extreme positions.
The normal operation of the internal combustion engine can only be ensured by a uniform supply of the fuel mixture at the right time. To reduce the operating costs of the motor for heat dissipation and prevent premature wear of the driving components, they are lubricated with oil.
The principle of operation of the internal combustion engine
Modern internal combustion engines run on the fuel that is ignited inside the cylinders and the energy that comes from it. A mixture of gasoline and air is supplied through the intake valve (in many engines there are two per cylinder). In the same place, it ignites due to the spark that forms spark plug... At the moment of a mini-explosion, the gases in the working chamber expand, creating pressure. It drives the piston attached to the KShM.
Diesel engines work on a similar principle, only the combustion process is initiated in a slightly different way. Initially, the air in the cylinder is compressed, which causes it to heat up. Before the piston reaches TDC on the compression stroke, the injector atomizes fuel. Due to the hot air, the fuel ignites on its own without a spark. Further, the process is identical to the gasoline modification of the internal combustion engine.
The process while the piston moves up or down is called a stroke. All measures until they are repeated are called a cycle.
One cycle includes the process of suction, compression, ignition together with the expansion of the formed gases, release.
There are two modifications of motors:
- In a two-stroke cycle, the crankshaft turns once per cycle, and the piston moves down and up.
- In a four-stroke cycle, the crankshaft will turn twice per cycle, and the piston will make four complete movements - it will go down, rise, fall, rise.
The principle of operation of a two-stroke engine
When the driver starts the engine, the starter sets the flywheel in motion, the crankshaft turns, the KShM moves the piston. When it reaches BDC and begins to rise, the working chamber is already filled with a combustible mixture.
At the top dead center of the piston, it ignites and moves it down. Further ventilation takes place - the exhaust gases are displaced by a new portion of the working combustible mixture. Purge can be different depending on the design of the motor. One of the modifications provides for filling the sub-piston space with the fuel-air mixture when it rises, and when the piston descends, it is squeezed into the working chamber of the cylinder, displacing the combustion products.
In such modifications of motors, there is no valve timing system. The piston itself opens / closes the inlet / outlet.
Such motors are used in low-power technology, because gas exchange in them occurs due to the replacement of exhaust gases with the next portion of the air-fuel mixture. Since the working mixture is partially removed along with the exhaust, this modification is distinguished by increased fuel consumption and lower power compared to four-stroke analogues.
One of the advantages of such internal combustion engines is less friction per cycle, but at the same time they heat up more strongly.
How the four-stroke engine works
Most cars and other motor vehicles are equipped with four-stroke engines. A gas distribution mechanism is used to supply the working mixture and remove the exhaust gases. It is driven through a timing drive connected to the crankshaft pulley by a belt, chain or gear drive.
Rotating camshaft raises / lowers the intake / exhaust valves located above the cylinder. This mechanism ensures the synchronization of the opening of the corresponding valves for supplying the combustible mixture and removing the exhaust gases.
In such engines, the cycle occurs as follows (for example, a gasoline engine):
- At the moment the engine is started, the starter turns the flywheel, which drives the crankshaft. The inlet valve opens. The crank mechanism lowers the piston, creating a vacuum in the cylinder. There is a suction stroke of the air-fuel mixture.
- Moving from bottom dead center upwards, the piston compresses the combustible mixture. This is the second measure - compression.
- When the piston is at top dead center, the spark plug creates a spark that ignites the mixture. Due to the explosion, the gases expand. Excess pressure in the cylinder moves the piston downward. This is the third cycle - ignition and expansion (or working stroke).
- The rotating crankshaft moves the piston upward. At this point, the camshaft opens the exhaust valve through which the rising piston expels the exhaust gases. This is the fourth bar - release.
Internal combustion engine auxiliary systems
No modern internal combustion engine is capable of operating independently. This is because the fuel must be delivered from the gas tank to the engine, it must ignite at the right time, and so that the engine does not "suffocate" from the exhaust gases, they must be removed in time.
Rotating parts need constant lubrication. Due to the increased temperatures generated during combustion, the engine must be cooled. These accompanying processes are not provided by the motor itself, therefore the internal combustion engine works in conjunction with auxiliary systems.
This auxiliary system is designed for timely ignition of the combustible mixture at the appropriate piston position (TDC in the compression stroke). It is used on gasoline internal combustion engines and consists of the following elements:
- Power supply. When the engine is at rest, this function is performed by the battery (how to start a car if the battery is dead, read in separate article). After starting the engine, the energy source is generator.
- Egnition lock. A device that closes an electrical circuit to power it from a power source.
- Storage device. Most gasoline vehicles have an ignition coil. There are also models in which there are several such elements - one for each spark plug. They convert the low voltage from the battery to the high voltage needed to create a high-quality spark.
- Distributor-interrupter of ignition. In carburetor cars, this is a distributor, in most others, this process is controlled by an ECU. These devices distribute electrical impulses to the appropriate spark plugs.
To create a combustion process, a combination of three factors is required: fuel, oxygen and an ignition source. If an electrical discharge is applied - the task of the ignition system, then the intake system provides oxygen to the engine so that the fuel can ignite.
This system consists of:
- Air intake - a branch pipe through which clean air is taken. The admission process depends on the engine modification. In atmospheric engines, air is sucked in due to the creation of a vacuum that forms in the cylinder. In turbocharged models, this process is enhanced by the rotation of the supercharger blades, which increases the engine power.
- The air filter is designed to clean the flow from dust and small particles.
- The throttle valve is a valve that regulates the amount of air entering the motor. It is regulated either by pressing the accelerator pedal or by the electronics of the control unit.
- The intake manifold is a system of pipes connected to one common pipe. In injection internal combustion engines, a throttle valve is installed on top and a fuel injector for each cylinder. In carburetor modifications, a carburetor is installed on the intake manifold, in which air is mixed with gasoline.
In addition to air, fuel must be supplied to the cylinders. For this purpose, a fuel system has been developed, consisting of:
- fuel tank;
- fuel line - hoses and pipes through which gasoline or diesel fuel moves from the tank to the engine;
- carburetor or injector (nozzle systems that spray fuel);
- fuel pumppumping fuel from a tank to a carburetor or other device for mixing fuel and air;
- a fuel filter that cleans gasoline or diesel fuel from debris.
Today, there are many modifications of engines in which the working mixture is fed into the cylinders by different methods. Among such systems there are:
- single injection (carburetor principle, only with a nozzle);
- distributed injection (a separate nozzle is installed for each cylinder, the air-fuel mixture is formed in the intake manifold channel);
- direct injection (the nozzle sprays the working mixture directly into the cylinder);
- combined injection (combines the principle of direct and distributed injection)
All rubbing surfaces of metal parts must be lubricated to cool and reduce wear. To provide this protection, the motor is equipped with a lubrication system. It also protects metal parts from oxidation and removes carbon deposits. The lubrication system consists of:
- sump - a reservoir that contains engine oil;
- an oil pump that creates pressure, thanks to which lubricant is supplied to all parts of the motor;
- an oil filter that traps any particles resulting from the operation of the motor;
- some cars are equipped with an oil cooler for additional cooling of the engine lubricant.
A high-quality exhaust system ensures the removal of exhaust gases from the working chambers of the cylinders. Modern cars are equipped with an exhaust system, which includes the following elements:
- an exhaust manifold that dampens vibrations of hot exhaust gases;
- a receiving pipe, into which the exhaust gases come from the manifold (like the exhaust manifold, it is made of heat-resistant metal);
- a catalyst that cleans exhaust gases from harmful elements, which allows the vehicle to comply with environmental standards;
- resonator - a capacity slightly smaller than the main muffler, designed to reduce the exhaust speed;
- the main muffler, inside which there are partitions that change the direction of the exhaust gases to reduce their speed and noise.
This additional system allows the motor to run without overheating. She supports engine operating temperaturewhile it's wound up. So that this indicator does not exceed the critical limits even when the car is stationary, the system consists of the following parts:
- cooling radiatorconsisting of tubes and plates designed for rapid heat exchange between the coolant and ambient air;
- a fan that provides a higher air flow, for example, if the machine is in a traffic jam and the radiator is not sufficiently blown;
- a water pump, thanks to which the circulation of the coolant is provided, which removes heat from the hot walls of the cylinder block;
- thermostat - a valve that opens after the engine warms up to operating temperature (before it is triggered, the coolant circulates in a small circle, and when it opens, the liquid moves through the radiator).
Synchronous operation of each auxiliary system ensures the smooth operation of the internal combustion engine.
A cycle refers to actions that are repeated in a single cylinder. The four-stroke motor is equipped with a mechanism that triggers each of these cycles.
In the internal combustion engine, the piston performs reciprocating movements (up / down) along the cylinder. The connecting rod and the crank attached to it convert this energy into rotation. During one action - when the piston reaches from the lowest point to the top and back - the crankshaft makes one revolution around its axis.
For this process to occur constantly, an air-fuel mixture must enter the cylinder, it must be compressed and ignited in it, and combustion products must also be removed. Each of these processes takes place in one crankshaft revolution. These actions are called bars. There are four of them in a four-stroke:
- Intake or suction. At this stroke, an air-fuel mixture is sucked into the cylinder cavity. It enters through an open intake valve. Depending on the type of fuel system, gasoline is mixed with air in the intake manifold or directly in the cylinder, such as in diesel engines;
- Compression. At this point, both the intake and exhaust valves are closed. The piston moves up due to cranking of the crankshaft, and it rotates due to performing other strokes in adjacent cylinders. In a gasoline engine, VTS is compressed to several atmospheres (10-11), and in a diesel engine - more than 20 atm;
- Working stroke. At the moment when the piston stops at the very top, the compressed mixture is ignited using a spark from a spark plug. In a diesel engine, this process is slightly different. In it, the air is compressed so much that its temperature jumps to a value at which the diesel fuel ignites on its own. As soon as an explosion of a mixture of fuel and air occurs, the released energy has nowhere to go, and it moves the piston down;
- Combustion products release. In order to fill the chamber with a fresh portion of the combustible mixture, the gases formed as a result of ignition must be removed. This happens in the next stroke when the piston goes up. At this moment, the outlet valve opens. When the piston reaches top dead center, the cycle (or set of strokes) in a separate cylinder is closed, and the process is repeated.
ICE advantages and disadvantages
Today the best engine option for motor vehicles is ICE. Among the advantages of such units are:
- ease of repair;
- economy for long trips (depends on its volume);
- large working resource;
- accessibility for a motorist of average income.
The ideal motor has not yet been created, so these units also have some disadvantages:
- the more complex the unit and related systems, the more expensive their maintenance (for example, EcoBoost motors);
- requires fine tuning of the fuel supply system, ignition distribution and other systems, which requires certain skills, otherwise the engine will not work efficiently (or will not start at all);
- more weight (compared to electric motors);
- wear of the crank mechanism.
Despite equipping many vehicles with other types of motors ("clean" cars powered by electric traction), internal combustion engines will maintain a competitive position for a long time due to their availability. Hybrid and electric versions of cars are gaining popularity, however, due to the high cost of such vehicles and the cost of their maintenance, they are not yet available to the average motorist.