In the cylinder-piston group (CPG) there is one of the main processes, so that the engine internal combustion Functions: Energy isolation as a result of combustion of the fuel and air mixture, which is subsequently converted into a mechanical action - the rotation of the crankshaft. The main working component of the CPG is a piston. Thanks to it, the conditions necessary for combustion conditions are created. The piston is the first component involved in the transformation of the resulting energy.
Cylindrical shape engine piston. It is located in the engine cylinder sleeve, this is a movable element - during the work it makes reciprocating movements, which is why the piston performs two functions.
- With progressive movement, the piston reduces the volume of the combustion chamber, compressing fuel mixtureIt is necessary for the combustion process (in diesel engines ignition of the mixture and comes at all from its strong compression).
- After the ignition of the fuel and air mixture in the combustion chamber, the pressure increases sharply. In an effort to increase the volume, it pushes the piston back, and it makes the return movement, transmitting through the crankshaft rod.
DESIGN
The detail device includes three components:
- Bottom.
- Sealing part.
- Skirt.
These components are available both in solicular pistons (the most common option) and in composite details.
BOTTOM
The bottom is the main working surface, since it, the walls of the sleeve and the head of the block form the combustion chamber, in which the fuel mixture is burning.
The main bottom parameter is a form that depends on the type of internal combustion engine (DVS) and its design features.
In the two-stroke engines, pistons are used, in which the bottom of the spherical form is the protrusion of the bottom, it increases the efficiency of filling the combustion chamber with a mixture and removal of spent gases.
In four-stroke gasoline engines, the bottom is flat or concave. Additionally, technical recesses are done on the surface - recesses under valve plates (eliminate the likelihood of a piston collision with a valve), recesses for improving mixing formation.
In diesel engines of deepening in the bottom are the most dimensions and have different shapes. Such recesses are called a piston combustion chamber and they are intended to create twists when air and fuel in the cylinder is supplied to ensure better mixing.
The sealing part is intended for the installation of special rings (compression and oiling), the task of which is to eliminate the gap between the piston and the wall of the sleeve, preventing the breakthrough of the working gases into the rigorous space and lubrication - to the combustion chamber (these factors reduce the motorcycle efficiency). This ensures the heat dissipation from the piston to the sleeve.
Sealing part
The sealing part includes a groove in the cylindrical surface of the piston - the grooves located behind the bottom, and the jumpers between the grooves. In the two-stroke engines in the groove, special inserts are additionally placed in which the castles of the rings are resting. These inserts are needed to exclude the probability of turning the rings and enter their locks into intake and exhaust windows, which can cause their destruction. 
The jumper from the edge of the bottom and to the first rings is called a heat belt. This belt perceives the greatest temperature effect, so the height is selected, based on the working conditions created within the combustion chamber, and the material of the manufacture of the piston.
The number of grooves done on the sealing part corresponds to the number of piston rings (and they can be used 2 - 6). The design with three rings is the most common - two compression and one scale.
In the groove under the oil lifting ring, the holes for the oil stack are done, which is removed by the ring from the wall of the sleeve.
Together with the bottom, the sealing part forms the head of the piston.
SKIRT
The skirt performs the role of a guide for the piston, not allowing it to change the position relative to the cylinder and providing only the reciprocating movement of the part. Thanks to this component, a movable piston connection is carried out with a connecting rod.
To connect in the skirt, the holes are done to install the piston finger. To increase the strength at the point of contact of the finger, with inner Skirts made special massive breaths, called bobbies.
To fix the piston finger in the piston in the installation holes under it, grooves for locking rings are provided.
Types of pistons
In internal combustion engines, two types of pistons differ in a structural device are used - solid and composite.
One-piece parts are made by casting followed by mechanical processing. In the process of casting from metal, a workpiece is created, which is given a common form of the part. Further on metalworking machines in the workpiece obtained, work surfaces are processed, grooves under the rings are cut, technological holes and recesses are made.
In the composite elements, the head and skirt are separated, and in a single design they are collected during the installation on the engine. Moreover, the assembly in one part is carried out when the piston is connected to the connecting rod. For this, in addition to the holes under the piston finger in the skirt, there are special eye on the head.
The advantage of the composite pistons is the possibility of combining manufacturing materials, which increases the operational qualities of the part.
Materials manufacturing
Aluminum alloys are used as manufacturing material for solid pistons. Details from such alloys are characterized by low weight and good thermal conductivity. But at the same time aluminum is not high strength and heat-resistant material, which limits the use of pistons from it.
Cast pistons are made of cast iron. This material is durable and resistant to high temperatures. The disadvantage of them is a significant mass and weak thermal conductivity, which leads to a strong heating of the pistons during the engine operation. Because of this, they are not used on gasoline engines, since the high temperature causes the occurrence of a vibrant ignition (the fuel and air mixture is flammable from the contact with the disintegrations, and not from the spark of the spark plug).
The design of the composite pistons allows combining the specified materials to be combined. In such elements, the skirt is made of aluminum alloys, which ensures good thermal conductivity, and the head is made of heat-resistant steel or cast iron.
But also the elements of the component type have disadvantages, among which:
- ability to use only in diesel engines;
- greater weight compared with cast aluminum;
- the need to use piston rings from heat-resistant materials;
- higher price;
Because of these features, the scope of the use of composite pistons is limited, they are used only on large-sized diesel engines.
Video: Piston. The principle of engine piston. DEVICE
The main types of internal combustion engines and steam machines have one common drawback. It is that the reciprocating movement requires a transformation into a rotational movement. This, in turn, causes low productivity, as well as a sufficiently high wear of the details of the mechanism included in different types engines.
Pretty many people thought about creating such a motor in which the moving elements were only rotating. However, it was possible to solve this task only to one person. Felix Vankel - self-taught mechanic - became the inventor of a rotary-piston engine. For your life, this person did not receive any specialty, nor higher education. Consider further more rotor piston Engine Vankel.
Brief biography of the inventor
Felix Vankel was born in 1902, on August 13, in the small town of Lar (Germany). In the first world father of the future inventor died. Because of this, Vankel had to throw his studies in the gymnasium and make a seller's assistant in the shop selling books under the publisher. Thanks to this, he was addicted to reading. Felix studied engine specifications, automotive, mechanics independently. Knowledge he screamed from books that were sold in the shop. It is believed that the scheme of the Vankiel engine (more precisely, the idea of \u200b\u200bits creation) visited in a dream. It is not known, the truth is or not, but it can be said that the inventor possessed outstanding abilities, a burner for mechanics and peculiar
Pros and cons
The convertible movement of a reciprocating character is completely absent in the rotary engine. The pressure formation occurs in those chambers that are created using the convex surfaces of the rotor of the triangular shape and various parts of the case. Rotational motion rotor provides combustion. It can lead to a decrease in vibration and increase the speed of rotation. Due to the efficiency of efficiency, which is due to the rotary engine has dimensions much less than a conventional piston equivalent power engine.
The rotary engine has one main of all its components. This important component is called a triangular rotor that performs rotational movements within the stator. All three peaks of the rotor, thanks to this rotation, have a permanent connection with the inner wall of the housing. With this contact, combustion chambers are formed, or three volumes of closed type with gas. When rotational rotor movements occur inside the case, the volume of all three formed combustion chambers changes all the time, reminding the action of a conventional pump. All three side surfaces of the rotor work like a piston.
Inside the rotor is a small gear with external teeth, which is attached to the housing. A gear that is more in diameter is connected to this fixed gear, which sets the trajectory of rotational rotor movements inside the housing. Teeth in the greater gear internal.
For the reason that, together with the output shaft, the rotor is associated eccentric, the rotation of the shaft occurs like the handle will rotate the crankshaft. The output shaft will make turnover three times for each of the rotor revolutions.
The rotary engine has such an advantage as a small mass. The most basic engine of the rotary engine has small size and mass. In this case, the handling and characteristics of such an engine will be better. It turns out less weight due to the fact that the need for crankshaft, rods and pistons is simply absent.
The rotary engine has such dimensions that are much less conventional Engine appropriate power. Due to the smaller engine size, the handling will be much better, as well as the machine itself will become more spacious, both for passengers and for the driver.
All parts of the rotary engine are carried out continuous rotational movements in the same direction. The change in their movement occurs just as in the pistons of the traditional engine. Rotary engines are internally balanced. This leads to a decrease in the level of vibration itself. The power of the rotary engine seems much smoother and evenly.
The Vankel engine has a convex special rotor with three faces, which can be called its heart. This rotor performs rotational motions inside the cylindrical surface of the stator. The Mazda rotary engine is the world's first rotary engine, which was designed specifically for the production of serial nature. This development was made early in 1963.
What is RPD?
In the classic four-stroke engine, the same cylinder is used for various operations - injection, compression, combustion and release.In the Rotary Engine, each process is performed in a separate compartment of the camera. The effect is not much different from the separation of the cylinder by four compartments for each of the operations.
In the piston engine, the pressure occurs during the combustion of the mixture causes the pistons to move forward and backward in their cylinders. The connecting rods and the crankshaft converts this pushing movement into the rotational, necessary for the movement of the car.
IN rotor engine There is no rectilinear movement that it would be necessary to translate into the rotational. The pressure is formed in one of the compartments of the chamber forcing the rotor rotate, it reduces the vibration and increases the potential magnitude of the engine. As a result, great efficiency, and smaller sizes at the same power as the conventional piston engine.
How does the RPD work?
The function of the piston in the RAP is performed by the scholarships of the rotor, which converts the power of the pressure of gases into the rotational motion of the eccentric shaft. The rotor movement relative to the stator (outer case) is provided by a pair of gears, one of which is rigidly fixed on the rotor, and the second on the lateral lid of the stator. The gear itself is fixed on the engine housing. With her, the gear of the rotor from the gear wheel is rolling around it.
The shaft rotates in the bearings placed on the housing, and has a cylindrical eccentric on which the rotor rotates. The interaction of these gears ensures the expedient movement of the rotor relative to the housing, as a result of which three broken alternating volume cameras are formed. The gear ratio of gears 2: 3, so in one turnover of the eccentric shaft rotor returns to 120 degrees, and for the complete turnover of the rotor in each of the chambers there is a full four-stroke cycle. 
Gas exchange is regulated by the peak of the rotor when it passes through the intake and exhaust window. This design allows a 4-stroke cycle without the use of a special gas distribution mechanism.
The sealing of the chambers is provided by radial and end sealing plates, pressed against the cylinder by centrifugal forces, gas pressure and tape springs. The torque is obtained as a result of the operation of the gas forces through the rotor on the eccentric of the shaft of the mixing formation, inflammation, lubrication, cooling, launch - are fundamentally the same as the conventional piston internal combustion engine
Matching
In the theory in the RAP, several varieties of mixture formation are used: external and internal, based on liquid, solid, gaseous fuels.
Regarding solid fuels it is worth noting that they are initially gasified in gas generators, as they lead to elevated ash formation in the cylinders. Therefore, gaseous and liquid fuels received greater distribution in practice.
The mechanism of formation of the mixture in Vankel engines will depend on the type of fuel used.
When using gaseous fuel, its mixing with air occurs in a special compartment at the input to the engine. The combustible mixture in the cylinders enters the finished form.
From liquid fuel, the mixture is prepared as follows:
- The air is mixed with liquid fuel before entering the cylinders, where the combustible mixture comes.
- In the engine cylinders, the liquid fuel and air come separately, and mixing them inside the cylinder. The working mixture is obtained by contacting them with residual gases.
Accordingly, the fuel and air mixture can be prepared outside the cylinders or inside them. From this there is a separation of engines with internal or external formation of the mixture.
Technical characteristics of a rotary-piston engine
| parameters | VAZ-4132. | VAZ-415. |
| number of sections | 2 | 2 |
| Engine chamber work volume, ccm | 1,308 | 1,308 |
| compression ratio | 9,4 | 9,4 |
| Rated power, kW (hp) / min-1 | 103 (140) / 6000 | 103 (140) / 6000 |
| Maximum torque, n * m (kgf * m) / min-1 | 186 (19) / 4500 | 186 (19) / 4500 |
| The minimum frequency of rotation of the eccentric shaft on idlingmin-1 | 1000 | 900 |
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Engine mass, kg |
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Overall dimensions, mm |
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Oil consumption in% of fuel consumption |
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Engine resource to first overhaul, thousand km |
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purpose |
VAZ-21059/21079 |
VAZ-2108/2109/21099/2115/2110 |
models are produced
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engine RPD |
Acceleration time 0-100, sec |
Maximum speed, km \\ h |
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Efficiency of rotary-piston design
Despite the number of flaws, the studied studies have shown that the overall KPD of the Vankel engine is pretty high in modern standards. Its value is 40 - 45%. For comparison, the piston engines of the internal combustion of the efficiency is 25%, in modern turbo diesel engines - about 40%. The highest efficiency in piston diesel engines is 50%. So far, scientists continue to find reserves to enhance the efficiency of the engines.
The final efficiency of the motor operation consists of three main parts:
Studies in this area show that only 75% flammable burns in full. It is believed that this problem is solved by separating the combustion and expansion of gases. It is necessary to provide arrangement of special chambers under optimal conditions. The combustion should occur in a closed volume, subject to increasing temperature indicators and pressure, the expansion process should occur at low temperature indicators.
- The efficiency is mechanical (characterizes the work, the result of which was the formation of the main axis transmitted to the torque consumer).
About 10% of the motor operation is spent on bringing the auxiliary nodes and mechanisms. You can correct this flawping by making changes to the engine device: when the main moving working element does not touch the fixed body. The permanent torque should be present throughout the path of the main working element.
- Thermal efficacy (indicator reflecting the amount of thermal energy formed from combustion combustion, transforming into useful work).
In practice, 65% of the resulting thermal energy is destroyed with spent gases into an external environment. A number of studies showed that it is possible to increase thermal efficiency indicators when the engine design can allow combustion of a fuel in the heat insulated chamber so that the maximum temperature indicators be achieved, and at the end this temperature decreased to the minimum values \u200b\u200bby turning on the steam phase.
Rotary-piston vankiel engine
When burning fuel, thermal energy is distinguished. The engine in which the fuel combines directly inside the working cylinder and the energy of the gases obtained at the same time is perceived by the piston moving in the cylinder, refer to the piston.
So, as already mentioned earlier, the engine of this type is the main for modern cars.
In such engines, the combustion chamber is placed in a cylinder, in which the thermal energy from the combustion of the fuel and air mixture is converted into the mechanical energy of the piston moving progressively and then a special mechanism called the crank-connecting rolling. crankshaft.
At the place of formation of a mixture consisting of air and fuel (combustion), piston engineers are divided into engines with an external and internal conversion.
At the same time, the engines with external mixture formation by the nature of the fuel used are divided into carburetor and injection, operating on light liquid fuel (gasoline) and gas-operating gas (gas generator, luminous, natural gas, etc.). Engines with compression ignition are diesel engines (diesel engines). They work on heavy liquid fuel ( diesel fuel). In general, the design of the engines themselves is almost the same.
The operating cycle of four-stroke engines in the piston performance is performed when the crankshaft makes two turns. By definition, it consists of four separate processes (or clocks): inlet (1 tact), compression of the fuel and air mixture (2 tact), working stroke (3 tact) and exhaust gases (4 tact).
The change of engine work clocks is provided with a gas distribution mechanism consisting of distribution Vala, transfer system of pushers and valves, insulating the working space of the cylinder from the external environment and mainly ensure the shift of the phases of gas distribution. Due to the inertiality of gases (singularities of gas dynamics processes) intake and release tacts for real Engine overlap, which means their joint action. At high speed, the overlap of the phases affects the engine at work. On the contrary, than it is more on low revs, the smaller the engine torque. In work modern engines This phenomenon is taken into account. Create devices to change the phases of gas distribution during operation. There are various designs of such devices most suitable of which are electromagnetic devices for adjusting the phases of gas distribution mechanisms (BMW, Mazda).
Carburetor DVS
IN carburetor engines The fuel and air mixture is prepared before its entry into the engine cylinders, in a special device - in the carburetor. In such engines, a combustible mixture (a mixture of fuel and air) entered the cylinders and mixed with the remnants of the exhaust gases (working mixture) flammifies from an extraneous energy source - the electrical spark of the ignition system.
Injector DVS
In such engines, due to the presence of spraying nozzles, carrying out gasoline injection into the intake manifold, mixing with air.
Gas economy
In these engines, the gas pressure after exiting the gas gearbox is greatly reduced and brought to close atmospheric, after which, with the help of an air-gas mixer, it is absorbed by electrical injectors (similar to injection engines) in the intake manifold engine.
The ignition, as in the previous types of engines, is carried out from the spark of the candle slipsing between its electrodes.
Diesel DVS
In diesel engines, the mixing formation occurs directly inside the engine cylinders. Air and fuel enroll in cylinders separately.
At the same time, at first, only the air comes into the cylinders, it is compressed, and at the time of its maximum compression, the jet of fine fuel through a special nozzle is injected into the cylinder (the pressure inside the cylinders of such engines reaches much greater values \u200b\u200bthan in the previous type engines), the inflammation of the formed Mixtures.
In this case, the ignition of the mixture occurs as a result of an increase in air temperature in its strong compression in the cylinder.
Among the disadvantages of diesel engines, it is possible to highlight higher, compared to previous types of piston engines - the mechanical tension of its parts, in particular the crank-connecting mechanism, requiring improved strength qualities and, as a result, large dimensions, weight and cost. It increases due to the complicated design of the engines and the use of better materials.
In addition, such engines are characterized by inevitable soot emissions and an increased content of nitrogen oxides in exhaust gases due to heterogeneous combustion of the working mixture inside the cylinders.
Gasiodialistics
The principle of operation of such an engine is similar to the operation of any of the varieties of gas engines.
The fuel and air mixture is prepared according to a similar principle by supplying gas to an air-gas mixer or in the intake manifold.
However, the mixture is ignited by the replacement portion of diesel fuel injected into the cylinder by analogy with the operation of diesel engines, and not using an electrical candle.
Rotary-piston DVS
In addition to the established name, this engine has the name by the name of the inventor who created his inventor and is called the Vankel engine. Offered at the beginning of the 20th century. Currently, manufacturers of Mazda RX-8 are engaged in such engines.
The main part of the engine forms a triangular rotor (piston analog), rotating in a specific form chamber, according to the design of the inner surface, resembling the number "8". This rotor performs the function of the piston of the crankshaft and the gas distribution mechanism, thus eliminating the gas distribution system, mandatory for piston engines. It performs three full working cycles for one of its turnover, which allows one such engine to replace the six-cylinder piston engine. Despite a lot of positive qualities, among which also the fundamental simplicity of its design, has disadvantages that impede its widespread use. They are associated with the creation of durable reliable chamber seals with a rotor and the construction of the necessary engine lubrication system. The working cycle of rotary-piston engines consists of four clocks: the intake of the fuel-air mixture (1 tact), compression of the mixture (2 tact), expansion of the combusting mixture (3 tact), release (4 tact).
Rotary-Bad DVS
This is the same engine that is applied in E-mobile.
Gas turbine DVS
Already today, these engines are successfully able to replace the piston engine in cars. And although the degree of perfection design of these engines reached only in the past few years, the idea of \u200b\u200bapplying gas turbine engines in cars has arisen a long time ago. The real possibility of creating reliable gas turbine engines is now provided by the theory of blade engines, which has reached a high level of development, metallurgy and their production techniques.
What does the gas turbine engine represent? To do this, let's look at its principal scheme.
Compressor (post9) and gas turbine (pos. 7) are on the same shaft (pos.8). The shaft of the gas turbine rotates in the bearings (pos.10). The compressor takes the air from the atmosphere, compresses it and sends to the combustion chamber (pos.3). Fuel pump (pos.1) is also driven by a turbine shaft. It serves fuel to the nozzle (pos.2), which is installed in the combustion chamber. Gaseous combustion products come through the guide apparatus (pos.4) of the gas turbine on the blade of its impeller (pos.5) and cause it to rotate in a given direction. The spent gases are produced into the atmosphere through the nozzle (pos.6).
And although this engine is full of flaws, they are gradually eliminated by design. At the same time, compared with piston DVS, gas turbine DVS has a number of significant advantages. First of all, it should be noted that as a steam turbine, gas can develop large revs. Which allows you to get high power from smaller in size and lighter by weight (almost 10 times). In addition, the only type of movement in the gas turbine is rotational. At the piston engine, in addition to the rotational, there are reciprocating movements of pistons and complex movements of rods. Also gas turbine engines do not require special cooling systems, lubricants. The absence of significant friction surfaces with a minimal amount of bearings provide long-term operation and high reliability of the gas turbine engine. Finally, it is important to note that the power is carried out using kerosene or diesel fuel, i.e. Cheaper species than gasoline. Holding the development of automotive gas turbine engines The reason is the need for artificial limiting the temperature of the gas turbines entering the blades, since there are still very roads high-state metals. As a result reduces useful use (Efficiency) of the engine and increases the specific fuel consumption (the amount of fuel per 1 hp). For passenger and freight car engines The gas temperature has to be limited to the limits of 700 ° C, and in aircraft engines up to 900 ° C. Modako today there are some ways to increase the efficiency of these engines by removing the heat of the exhaust gases to heal the air combustion entering the chamber. The solution to the problem of creating a highly economical automobile gas turbine engine largely depends on the success of work in this area.
Combined DVS
A great contribution to the theoretical aspects of the work and the creation of combined engines was introduced by an engineer of the USSR, Professor A.N. Schest.
Alexey Nesterovich Rustle
These engines are a combination of two machines: piston and shovel, which can act as a turbine or compressor. Both of these machines are important elements workflow. As an example of such an engine with gas turbine superior. In this case, in the usual piston engine, with the help of a turbocharger, a coercive air supply to the cylinders occurs, which allows you to increase the power of the engine. It is based on the use of exhaust gas flow energy. It affects the impeller of the turbine, fixed on the shaft on the one hand. And spins it. On the same shaft, on the other hand, the blades of the compressor are located. Thus, with the help of the compressor, the air is injected into the engine cylinders due to the vacuum in the chamber on one side and forced air supply, on the other hand, a large amount of air and fuel mixture comes into the engine. As a result, the volume of combustable fuel increases and the gas formed as a result of this combustion takes longer volumes, which creates greater power on the piston.
Two-stroke
This is referred to as the OI with an unusual gas distribution system. It is implemented in the process of passing the piston making reciprocating movements, two pipes: intake and graduation. You can meet his foreign designation "RCV".
Engine work processes are performed during one crankshaft turnover and two piston strokes. The principle of work is as follows. First, the cylinder is purned, which means the inlet of a combustible mixture with simultaneous intake of exhaust gases. Then there is a compression of the working mixture, at the time of the rotation of the crankshaft by 20--30 degrees from the position of the corresponding NMT when moving to the VMT. And the working stroke, the length of the piston stroke from the upper dead point (VTT) without reaching the lower dead point (NMT) by 20--30 degrees on the crankshaft revolutions.
There are obvious shortcomings of two-stroke engines. Firstly, the faint of the two-stroke cycle is the blowing of the engine (again with t. Gas dynamics). This happens on the one hand due to the fact that, the separation of fresh charge from exhaust gases It is impossible to ensure, i.e. Inevitable losses essentially flying into exhaust pipe Fresh mixture, (or air if we are talking about diesel). On the other hand, the work move lasts less than half of the turnover, which is already talking about the decline in the efficiency of the engine. Finally the duration of an extremely important gas exchange process, in a four-stroke engine occupying half of the working cycle, cannot be increased.
Two-stroke engines are more complicated and more expensive at the expense of the mandatory use of the purge system or the supervision system. There is no doubt that the increased thermal tension of the details of the cylindroport group requires the use of more expensive materials of individual parts: pistons, rings, cylinder sleeves. Also, performing the piston of gas distribution functions imposes a limit on its height size consisting of the height of the piston stroke and the height of the windows for purge. It is not as critical in the moped, but significantly weights the piston when installing it on vehicles requiring significant power costs. Thus, when power is measured with tens, and even hundreds horse powerThe increase in the mass of the piston is very noticeable.
Nevertheless, certain works were carried out towards improving such engines. In the Ricardo engines, special distribution sleeves were introduced with a vertical move, which was a certain attempt to make a possible reduction in the dimensions and weight of the piston. The system turned out to be quite complicated and very expensive in performance, so such engines were used only in aviation. It is necessary to additionally notice that there are twice as large warmness exhaust valves (with direct-flow valve purge) in comparison with the valves of four-stroke engines. In addition, there are a longer direct contact with the spent gases, and therefore the worst heat sink.
Six-contact economy
The basis of the work is based on the principle of operation of the four-stroke engine. Additionally, its designs have elements that, on the one hand, increase its efficiency, while on the other hand reduce its loss. There are two of different types such engines.
In engines operating on the basis of OTO cycles and diesel, there are significant heat losses during fuel combustion. These losses are used in the engine of the first design as an additional power. In the designs of such engines additionally fuel-air mixture, pairs or air are used as a working medium for an additional piston running, as a result of which the power increases. In such engines, after each fuel injection, the pistons move three times in both directions. In this case, there are two working strokes - one with fuel, and the other with steam or air.
The following engines have been created in this area:
engine Bayulas (from English. Bajulaz). Baulas (Switzerland) was created;
engine Crowera (from English Crower). Invented by Bruce Croweer (USA);
Bruce Croweer
The engine engine (from the English. Velozeta) was built in an engineering college (India).
The principle of operation of the second type of engine is based on the use of an additional piston in its design on each cylinder and located opposite the main one. The additional piston moves with a reduced twice with respect to the main piston frequency, which provides for each cycle six pistons. Additional piston in its primary purpose replaces the traditional gas distribution mechanism of the engine. The second function consists in increasing the degree of compression.
The main, independently created constructions of such engines two:
engine Bir HED (from English Beare Head). Invented Malcolm Bir (Australia);
engine with the name "Charged Pump" (from English. German Charge Pump). Invented Helmut Kotman (Germany).
What will be in the near future with the internal combustion engine?
In addition to the flaws specified at the beginning of the article, there is another principal disadvantage of not allowing the use of DVS separately from the car transmission. Force aggregate The car is formed by the engine together with a vehicle transmission. It allows you to move the car at all necessary speeds. But separately taken in the engine develops highest power Only in a narrow range of revolutions. This is the actually why the transmission is necessary. Only in exceptional cases cost without transmission. For example, in some plane structures.
Definition.
Piston Engine - one of the embodiments of the internal combustion engine, working through the transformation of the internal energy of the combusting fuel in mechanical work progressive movement of piston. The piston comes in motion when expanding the working fluid in the cylinder.
The crank-connecting mechanism converts the translational movement of the piston into the rotational motion of the crankshaft.
The operating cycle of the engine consists of a sequence of tact of one-sided translational strokes of the piston. The engines with two and four clocks of work are subdivided.
The principle of operation of the two-stroke and four-stroke piston engines.
Number of cylinders B. piston engines It may vary depending on the design (from the 1st to 24). The engine volume is assumed to be equal to the sum of the volumes of all cylinders, the capacity of which is found on the product of the cross section on the stroke of the piston.
IN piston engines Different designs in different ways are the process of fuel ignition:
Electrical dischargewhich is formed on the ignition candlelight. Such engines can operate both on gasoline and other types of fuel (natural gas).
Squeezing of the working body:
IN diesel enginesoperating on diesel fuel or gas (with 5% by the addition of diesel fuel), air is compressed, and when the piston of maximum compression point is reached, the fuel injection occurs, which flammives from contact with heated air.
Engines compression model. Fuel supply in them exactly the same as in gasoline engines. Therefore, for their work, a special composition of fuel is needed (with impurities of air and diethyl ether), as well as accurate adjustment of the degree of compression. Compressor engines found their distribution in aircraft and automotive industry.
Kalil engines. The principle of their action is largely similar to the engines of the compression model, but it did not cost without construction features. The role of the ignition in them is performed - a calil candle, the intensity of which is maintained by the energy of the combusting fuel on the previous tact. The composition of the fuel is also special, the basis is taken by methanol, nitromethane and castor oil. Engines are used, both on cars and on airplanes.
Calorizator engines. In these engines, ignition occurs when fuel contact with hot engine parts (usually - the bottom of the piston). Martin gas is used as fuel. They are used as drive engines on rolling mills.
Fuel types used in piston engines:
Liquid fuel - diesel fuel, gasoline, alcohols, biodiesel;
Gases - natural and biological gases, liquefied gases, hydrogen, gaseous oil cracking products;
Produced in a gas generator from coal, peat and wood, carbon monoxide is also used as fuel.
Work of piston engines.
Engine operation cycles Details are painted in technical thermodynamics. Various cyclics are described by various thermodynamic cycles: Otto, diesel engine, atkinson or miller and trinker.
Causes of breakdowns of piston engines.
PDD piston engine.
Maximum efficiency that managed to get on piston Engine is 60%, i.e. A little less than half of the combusting fuel is spent on the heating of engine parts, and also comes out with heat exhaust gases. In this connection, it has to equip the engine cooling systems.
Classification of cooling systems:
Air S. - Give heat air due to the ribbed outer surface of the cylinders. Lie applied
bo on weak engines (dozens of hp), or on powerful aircraft engines, which are cooled by a rapid air flow.
Liquid SO - The liquid (water, antifreeze or oil) is used as a cooler, which pumps through the cooling shirt (channels in the cylinder block walls) and enters the cooling radiator in which it is cooled by air flows, natural or fans. Rarely, but a metal sodium is also used as a coolant, which is melted from heat heating engine.
Application.
Piston engines, due to its power range, (1 watt - 75,000 kW) have gained more popularity not only in the automotive industry, but also aircraft and shipbuilding. They are also used to drive combat, agricultural and construction equipment, electric generators, water pumps, chainsaws and other machines, both mobile and stationary.
In the cylinder-piston group (CPG), one of the main processes occurs, due to which the internal combustion engine is functioning: the excretion of energy as a result of burning the fuel-air mixture, which is subsequently converted into a mechanical action - the rotation of the crankshaft. The main working component of the CPG is a piston. Thanks to it, the conditions necessary for combustion conditions are created. The piston is the first component involved in the transformation of the resulting energy.
Engine piston has a cylindrical shape. It is located in the engine cylinder sleeve, this is a moving element - during the work it makes reciprocating movements and performs two functions.
- In priglier movement, the piston reduces the volume of the combustion chamber, squeezing the fuel mixture, which is necessary for the combustion process (in diesel engines, the ignition of the mixture is completely due to its strong compression).
- After the ignition of the fuel and air mixture in the combustion chamber, the pressure increases sharply. In an effort to increase the volume, it pushes the piston back, and it makes the return movement, transmitting through the crankshaft rod.
What is the piston of the engine internal combustion of the car?
The detail device includes three components:
- Bottom.
- Sealing part.
- Skirt.
These components are available both in solicular pistons (the most common option) and in composite details.
Bottom
The bottom is the main working surface, since it, the walls of the sleeve and the head of the block form the combustion chamber, in which the fuel mixture is burning.
The main bottom parameter is a form that depends on the type of internal combustion engine (DVS) and its design features.
In the two-stroke engines, pistons are used, in which the bottom of the spherical form is the protrusion of the bottom, it increases the efficiency of filling the combustion chamber with a mixture and removal of spent gases.
In four-stroke gasoline engines, the bottom is flat or concave. Additionally, technical recesses are done on the surface - recesses under valve plates (eliminate the likelihood of a piston collision with a valve), recesses for improving mixing formation.
In diesel engines of deepening in the bottom are the most dimensions and have different shapes. Such recesses are called a piston combustion chamber and they are intended to create twists when air and fuel in the cylinder is supplied to ensure better mixing.
The sealing part is intended for the installation of special rings (compression and oiling), the task of which is to eliminate the gap between the piston and the wall of the sleeve, preventing the breakthrough of the working gases into the rigorous space and lubrication - to the combustion chamber (these factors reduce the motorcycle efficiency). This ensures the heat dissipation from the piston to the sleeve.
Sealing part
The sealing part includes a groove in the cylindrical surface of the piston - the grooves located behind the bottom, and the jumpers between the grooves. In the two-stroke engines in the groove, special inserts are additionally placed in which the castles of the rings are resting. These inserts are needed to exclude the probability of turning the rings and enter their locks into intake and exhaust windows, which can cause their destruction. 
The jumper from the edge of the bottom and to the first rings is called a heat belt. This belt perceives the greatest temperature effect, so the height is selected, based on the working conditions created within the combustion chamber, and the material of the manufacture of the piston.
The number of grooves done on the sealing part corresponds to the number of piston rings (and they can be used 2 - 6). The design with three rings is the most common - two compression and one scale.
In the groove under the oil lifting ring, the holes for the oil stack are done, which is removed by the ring from the wall of the sleeve.
Together with the bottom, the sealing part forms the head of the piston.
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Skirt
The skirt performs the role of a guide for the piston, not allowing it to change the position relative to the cylinder and providing only the reciprocating movement of the part. Thanks to this component, a movable piston connection is carried out with a connecting rod.
To connect in the skirt, the holes are done to install the piston finger. To increase the strength at the point of contact of the finger, with the inside of the skirt, special massive glands, referred to as the bobbs.
To fix the finger in the piston in the installation holes under it there are grooves for locking rings.
Types of pistons
In internal combustion engines, two types of pistons differ in a structural device are used - solid and composite.
One-piece parts are made by casting followed by mechanical processing. In the process of casting from metal, a workpiece is created, which is given a common form of the part. Further on metalworking machines in the workpiece obtained, work surfaces are processed, grooves under the rings are cut, technological holes and recesses are made.
In the composite elements, the head and skirt are separated, and in a single design they are collected during the installation on the engine. Moreover, the assembly in one part is carried out when the piston is connected to the connecting rod. For this, in addition to holes under the finger in the skirt, there are special eyes on the head.
The advantage of the composite pistons is the possibility of combining manufacturing materials, which increases the operational qualities of the part.
Materials manufacturing
Aluminum alloys are used as manufacturing material for solid pistons. Details from such alloys are characterized by low weight and good thermal conductivity. But at the same time aluminum is not high strength and heat-resistant material, which limits the use of pistons from it.
Cast pistons are made of cast iron. This material is durable and resistant to high temperatures. The disadvantage of them is a significant mass and weak thermal conductivity, which leads to a strong heating of the pistons during the engine operation. Because of this, they are not used on gasoline engines, since the high temperature causes the occurrence of a vibrant ignition (the fuel and air mixture is flammable from the contact with the disintegrations, and not from the spark of the spark plug).
The design of the composite pistons allows combining the specified materials to be combined. In such elements, the skirt is made of aluminum alloys, which ensures good thermal conductivity, and the head is made of heat-resistant steel or cast iron.
But also the elements of the component type have disadvantages, among which:
- the ability to use only in diesel engines;
- greater weight compared with cast aluminum;
- the need to use piston rings from heat-resistant materials;
- higher price;
Because of these features, the scope of the use of composite pistons is limited, they are used only on large-sized diesel engines.
Video: Engine Piston Operation Principle. Device
