Most of the car makes it move the piston internal combustion engine (abbreviated ICC) with a crank-connecting mechanism. This design received a mass distribution due to the low cost and technological production, relatively small dimensions and weights.
According to the type of fuel used, the KHC can be divided into gasoline and diesel. I must say that gasoline engines work perfectly on. This division directly affects the engine designs.
How the piston internal combustion engine is arranged
The basis of its design is a block of cylinders. This is a housing, cast from cast iron, aluminum or sometimes magnesium alloy. Most mechanisms and details of other engine systems are attached to the cylinder block, or are located inside it.
Another major engine item is his head. It is in the upper part of the cylinder block. The head also contains the parts of the engine systems.
Bottom to the cylinder block attached pallet. If this item perceives the load when the engine is operating, it is often referred to as a crankcase pallet, or a crankcase.
All engine systems
- crank mechanism;
- gas distribution mechanism;
- supply system;
- cooling system;
- lubrication system;
- ignition system;
- engine control system.
crank mechanism Consists of a piston, cylinder sleeve, connecting rod and crankshaft.
Crank mechanism:
1. The expander of the oil-oil ring. 2. Ring piston oil. 3. Ring compression, third. 4. Ring compression, second. 5. Ring compression, top. 6. Piston. 7. Ring stop. 8. Finger piston. 9. Shutun sleeve. 10. Shatun. 11. Cover rod. 12. The liner of the lower head of the rod. 13. Bolt covers connecting rod, short. 14. Bolt covers connecting rod, long. 15. Gear lead. 16. Plug of the oil channel of the connecting rod cervical. 17. Crankshaft bearing liner, top. 18. Crown toothed. 19. Bolts. 20. Flywheel. 21. Pins. 22. Bolts. 23. Oil reflector, rear. 24. Crankshaft rear bearing cap. 25. Pins. 26. Seafling stubborn bearing. 27. The liner of the crankshaft bearing, the bottom. 28. Advanced crankshaft. 29. Screw. 30. Crankshaft bearing cover. 31. Coupling bolt. 32. Bolt mounting bolt. 33. Shaft crankshaft. 34. Advanced, front. 35. Oil industry, front. 36. Nut Castle. 37. pulley. 38. Bolts.
The piston is located inside the cylinder sleeve. With the help of the piston finger, it is connected to the connecting rod, the lower head of which is attached to the rod crankshaft. The cylinder sleeve is a hole in the block, or the cast-iron sleeve inserted into the block.
Cylinder sleeve with block
Cylinder sleeve from above is closed by the head. The crankshaft is also attached to the block at its lower part. The mechanism converts the straightforward movement of the piston into the rotational motion of the crankshaft. The very rotation, which, ultimately, makes spinning the wheels of the car.
Gas distribution mechanism Responsible for the supply of a mixture of fuel and air vapor into space above the piston and removing combustion products through the valves opening strictly at a certain point in time.
The power system responds primarily for the preparation of a combustible mixture of the desired composition. The system devices store fuel, clean it, mixed with air so as to prepare a mixture of the desired composition and quantity. The system is also responsible for removing fuel combustion products from the engine.
When the engine is running, thermal energy is formed in an amount greater than the engine is capable of converting into mechanical energy. Unfortunately, the so-called thermal coefficient of efficiency, even the best samples of modern engines does not exceed 40%. Therefore, there is a large number of "extra" warmth to disperse in the surrounding space. This is what is engaged, it takes heat and maintains the stable operating temperature of the engine.
Lubrication system . This is exactly the case: "You will not fit, you will not go." In the internal combustion engines a large number of friction nodes and so-called sliding bearings: there is a hole, the shaft rotates in it. There will be no lubricant, from friction and overheating the node will fail.
Ignition system It is designed to set fire, strictly at a certain point in time, a mixture of fuel and air in space above the piston. There is no such system. There, fuel is self-proposal under certain conditions.
Video:
The engine control system using the electronic control unit (ECU) controls the engine systems and coordinates their operation. First of all, it is the preparation of a mixture of the desired composition and timely igniting it in the engine cylinders.
- ensures the transfer of mechanical effort to the connecting rod;
- responsible for sealing the fuel combustion chamber;
- provides timely removal of excess heat from the combustion chamber
The work of the piston takes place in difficult and largely dangerous conditions - with elevated temperature modes and reinforced loads, therefore it is especially important that the pistons for engines differ in efficiency, reliability and wear resistance. That is why lungs are used for their production, but heavy-duty materials are heat-resistant aluminum or steel alloys. Pistons are made by two methods - casting or stamping.
Piston design
The engine piston has a fairly simple design, which consists of the following details:
Volkswagen AG.
- Head of Piston KBS
- Piston finger
- Ring stopping
- Boss
- Shatun.
- Steel insert
- Compression ring first
- Compression ring second
- Outlooking ring
The design features of the piston in most cases depend on the type of engine, the shape of its combustion chamber and the type of fuel that is used.
Bottom
The bottom may have a different form depending on the functions performed - flat, concave and convex. The concave bottom shape ensures more efficient combustion chamber, but this contributes to greater formation of deposits when combustion of fuel. The bulging shape of the bottom improves the productivity of the piston, but at the same time reduces the efficiency of the combustion process of the fuel mixture in the chamber.
Piston rings
Below the bottoms are special grooves (furrows) to install piston rings. The distance from the bottom to the first compression ring is called the fire belt.
Piston rings are responsible for a reliable connection of the cylinder and piston. They provide reliable tightness due to dense adjustment to the walls of the cylinder, which is accompanied by a stressed friction process. Motor oil is used to reduce friction. For the manufacture of piston rings, a cast-iron alloy is used.
The number of piston rings, which can be installed in the piston depends on the type of engine used and its purpose. Often, systems with one oil-circulation ring and two compression rings (first and second) are installed.
Oil slurry ring and compression rings
The oiling ring provides timely elimination of excess oil from the inner walls of the cylinder, and the compression rings prevent gas from entering the crankcase.
The compression ring, located first, takes most of the inertial loads when the piston is running.
To reduce loads in many engines in the ring groove, steel insert is installed, increasing the strength and degree of compression of the ring. Compression type rings can be performed in the form of a trapezoid, barrels, cone, with a cut.
The oil surcharge ring in most cases is equipped with a plurality of oil drainage, sometimes a spring expander.
Piston finger
This is a tubular part that is responsible for a reliable piston connection with a connecting rod. It is made of steel alloy. When installing the piston finger in the bobbies, it is tightly fixed by special locking rings.
Piston, piston finger and rings together create a so-called piston engine group.
Skirt
Guide part of the piston device, which can be performed in the form of a cone or barrel. The piston skirt is equipped with two bugs for connecting with a piston finger.
To reduce rubbing losses, a thin layer of the antifriction substance is applied to the surface of the skirt (graphite or disulfide of molybdenum is often used). The lower part of the skirt is equipped with an oilmaging ring.
The mandatory process of operation of the piston device is its cooling, which can be carried out by the following methods:
- splashing oil through holes in a connecting rod or nozzle;
- the movement of the oil on the coil in the piston head;
- oil supply to the rings area through the ring canal;
- oil fog
Sealing part
The sealing part and the bottom are connected in the form of a piston head. In this part of the device there are piston rings - oil-chain and compression. Channels for rings have small holes through which the exhaust oil hits the piston, and then flows into the engine crankcase.
In general, the piston of the internal combustion engine is one of the most severely loaded parts, which is subjected to strong dynamic and at the same time thermal effects. This imposes increased requirements for both the materials used in the production of pistons and the quality of their manufacture.
The engine piston is a detail having a cylindrical shape and performing reciprocating movements inside the cylinder. It belongs to the number of details most characteristic of the engine, since the implementation of the thermodynamic process occurring in the DVS occurs precisely when it is assisted. Piston:
- perceiving gases pressure transmits the emerging force on;
- seals the combustion chamber;
- warning from her overwhelming heat.
The photo above shows four tact of engine piston.
Extreme conditions determine the material of the manufacture of pistons
The piston is operated in extreme conditions, characteristic features of which are high: pressure, inertial loads and temperatures. That is why the basic requirements for the materials for its manufacture are referred to:
- high mechanical strength;
- good thermal conductivity;
- low density;
- minor linear expansion coefficient, antifriction properties;
- good corrosion resistance.
Pistons can be:
- licenses;
- forged.
The design features of the piston are determined by its purpose
The main conditions defining the design of the piston are the type of engine and the form of the combustion chamber, the peculiarities of the combustion process passing in it. Constructively, the piston is a one-piece element consisting of:
- heads (bottoms);
- sealing part;
- skirts (guide part).
Is there a piston of a gasoline engine from diesel? The surfaces of the heads of the pistons of gasoline and diesel engines are distinguished constructively. In the gasoline engine, the head surface is flat or close to it. Sometimes there are grooves that contribute to the full opening of the valves. For the pistons of engines equipped with a direct fuel injection system (START), a more complex form is characteristic. The head of the piston in the diesel engine is significantly different from the gasoline, due to the combustion chamber of the specified form in it, a better twist and mixture formation is ensured.
In the photo of the engine piston scheme.
Piston rings: types and composition
The sealing part of the piston includes piston rings that ensure the density of the piston connection with the cylinder. The engine's technical condition is determined by its sealing ability. Depending on the type and purpose of the engine, the number of rings and their location are selected. The most common scheme is a diagram of two compression and one carbonic rings.
Piston rings are manufactured mainly from a special gray high-strength cast iron having:
- high stable strength and elasticity indicators in operating temperatures throughout the entire rings service period;
- high wear resistance under intensive friction;
- good antifriction properties;
- the ability of fast and efficient processing to the surface of the cylinder.
The main purpose of the compression ring is to obstruct the gas engine from the combustion chamber. Especially large loads come on the first compression ring. Therefore, in the manufacture of rings for the pistons of some forced gasoline and all diesel engines, an insertion of steel is installed, which increases the strength of the rings and allows for maximum degree of compression. In the form of compression rings can be:
- trapezoidal;
- tBCH;
- tconic.
The oil-chain ring is placed on the removal of excess oil from the walls of the cylinder and the obstruction of its penetration into the combustion chamber. It is distinguished by the presence of a plurality of drainage holes. In the designs of some rings there are spring expansion.
The shape of the guide part of the piston (otherwise, skirts) may be a cone-shaped or barrel-shapedthat allows you to compensate for its expansion when high operating temperatures achieve. Under their influence, the piston shape becomes cylindrical. The side surface of the piston in order to reduce the thread caused by friction is coated with a layer of antifriction material, for this purpose graphite or molybdenum disulfide is used. Thanks to the holes with tides made in the piston skirt, the piston finger is fixed.
A node consisting of a piston, compression, oil-chained rings, and the piston finger is called a piston group. The function of its connection to the connecting rod is assigned on a steel piston finger having a tubular shape. The requirements are presented to it:
- minimal deformation when working;
- high strength with variable load and wear resistance;
- good impact resistance;
- small mass.
- fixed in the piston bosses, but rotate in the head of the rod;
- fixed in the head of the rod and rotate in the piston bosses;
- freely rotating in the piston buses and in the rod head.
The fingers installed in the third option are called floating. They are the most popular because their wear in length and circle is insignificant and uniform. Upon their use, the danger of jamming is minimized. In addition, they are convenient when mounting.
Distraction of excess heat from the piston
Along with significant mechanical loads, the piston is also subject to the negative effects of extremely high temperatures. The heat from the piston group is given:
- cooling system from the walls of the cylinder;
- the inner cavity of the piston, then a piston finger and connecting rod, as well as oil circulating in the lubrication system;
- partially cold fuel-air mixture supplied to cylinders.
- splashing oil through a special nozzle or hole in the connecting rod;
- oil fog in the cylinder cavity;
- oil injection into the zone of the rings, in a special channel;
- circulation of oil in the piston head on a tubular coil.
Video about the four-stroke engine - the principle of operation:
The most famous and widely used all over the world mechanical devices are internal combustion engines (hereinafter DVS). The range is extensive, and they differ in a number of features, for example, the number of cylinders whose number can vary from 1 to 24 used by the fuel.
Work of the piston internal combustion engine
Single Cylinder DVS It can be considered the most primitive, unbalanced and having an uneven move, despite the fact that it is the starting point in creating multi-cylinder engines of the new generation. To date, they are used in aircraft production, in the production of agricultural, household and garden tools. For automotive industry, four-cylinder engines and more solid devices are massively used.
How does it and what is it?
Piston internal combustion engine It has a complex structure and consists of:
- The case, which includes a block of cylinders, the head of the cylinder block;
- Gas distribution mechanism;
- Crank-connecting mechanism (hereinafter CSM);
- A number of auxiliary systems.
KSM is a link between the energy of the fuel-air mixture released during the combustion of the air mixture (further) in the cylinder and the crankshaft that ensures the movement of the car. The gas distribution system is responsible for gas exchange in the process of functioning of the unit: the access of atmospheric oxygen and the TVS into the engine, and the timely removal of gases formed during the combustion.
The device of the simplest piston engine
Auxiliary systems are presented:
- Inlet, providing oxygen in the engine;
- Fuel represented by fuel injection system;
- Ignition providing a spark and ignition of fuel assemblies for gasoline engines (diesel engines are characterized by self-ignition of a mixture of high temperature);
- Lubrication system, which reduces the friction and wear of contacting metal parts using machine oil;
- Cooling system that does not allow overheating of engine parts, ensuring the circulation of special Tosol type liquids;
- A graduation system that reduces gases into the corresponding mechanism consisting of exhaust valves;
- The control system that monitors the functioning of the engine at the electronics level.
The main work element in the described node is considered piston internal combustion enginewhich itself is the team detail.
DVS piston device
Step-by-step scheme of operation
The work of the DVS is based on the energy of expanding gases. They are the result of the combustion of the TVS inside the mechanism. This physical process forces the piston to move in the cylinder. Fuel in this case can serve:
- Liquids (gasoline, dt);
- Gases;
- Carbon monoxide as a result of burning solid fuel.
Engine operation is a continuous closed cycle consisting of a certain number of clocks. The most common in 2 types of two types of clocks are most common:
- Two-stroke, compression and workforce;
- Four-stroke - characterized by four equal stages in the duration: inlet, compression, work move, and the final release, this indicates a fourfold change in the position of the main working element.
The start of the tact is determined by the location of the piston directly in the cylinder:
- Top dead dot (hereinafter NTC);
- Lower dead dot (Next NMT).
Studying the algorithm of the four-stroke sample, you can thoroughly understand principle of engine engine.
Principle of engine engine
The inlet occurs by passing out of the upper dead point through the entire cavity of the working piston cylinder with simultaneous tvs. Based on structural features, mixing incoming gases can occur:
- In the intake system manifold, it is relevant if the engine is gasoline with distributed or central injection;
- In the combustion chamber, if we are talking about a diesel engine, as well as an engine running on gasoline, but with direct injection.
First Takt. It passes with open valves of the gas distribution mechanism. The number of intake and release valves, their stay in the open position, their size and wear state are factors affecting the engine power. The piston at the initial stage of compression is placed in NMT. Subsequently, it begins to move up and compress the accumulated TVx to the sizes defined by the combustion chamber. The combustion chamber is free space in the cylinder, remaining between its top and piston in the upper dead point.
Second tact It assumes the closure of all engine valves. The density of their adjustment directly affects the quality of the compression of the FVS and its subsequent fire. Also on the quality of compression of the fuel assembly, the level of wear of components of the engine has a great influence. It is expressed in the size of the space between the piston and the cylinder, in the density of the valve adjacent. The engine compression level is the main factor affecting its power. It is measured by a special compressometer device.
Working Begins when the process is connected Ignition systemgenerating a spark. The piston is at the maximum top position. The mixture explodes, gases that create increased pressure are distinguished, and the piston is driven. The crank-connecting mechanism in turn activates the rotation of the crankshaft, which ensures the movement of the car. All system valves at this time are in a closed position.
Graduation tact It is completing in the cycle under consideration. All exhaust valves are in the open position, allowing the engine to "exhale" the combustion products. The piston returns to the starting point and is ready for the beginning of the new cycle. This movement contributes to the exhaust system, and then to the environment, exhaust gases.
Scheme of the engine of internal combustionAs mentioned above, based on cyclicity. Examined in detail how the piston engine works, It can be summarized that the efficiency of such a mechanism is not more than 60%. It is determined by such a percentage in that in a separate time, the working clock is performed only in one cylinder.
Not all the energy obtained at this time is directed to the movement of the car. Part it is spent on maintaining the flywheel movement, which inertia provides the operation of the car during three other clocks.
A certain amount of thermal energy is involuntarily spent on the heating of the housing and the exhaust gases. That is why the engine capacity of the car is determined by the number of cylinders, and as a result, the so-called engine volume calculated according to a certain formula as the total volume of all operating cylinders.
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.
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.
- 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.
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 the inside of the skirt, special massive glands, referred to as the bobbs.
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:
- 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: Piston. The principle of engine piston. DEVICE
