Let's say your son asks you: "Dad, what is the most amazing motor in the world"? What will you answer him? A 1000-horsepower unit from the Bugatti Veyron? Or the new AMG turbo engine? Or a twin-supercharged Volkswagen engine?
There have been a lot of cool inventions lately, and all those supercharged injections seem amazing... if you don't know. For the most amazing motor that I know of was made in the Soviet Union and, you guessed it, not for the Lada, but for the T-64 tank. It was called 5TDF, and here are some amazing facts.
It was a five-cylinder, which in itself is unusual. It had 10 pistons, ten connecting rods and two crankshafts. The pistons moved in the cylinders in opposite directions: first towards each other, then back, again towards each other, and so on. Power take-off was carried out from both crankshafts to make it convenient for the tank.
The engine worked on a two-stroke cycle, and the pistons played the role of spools that opened the intake and exhaust windows: that is, it did not have any valves or camshafts. The design was ingenious and efficient - a two-stroke cycle provided maximum liter power, and direct-flow scavenging - high-quality cylinder filling.
In addition, the 5TDF was a direct injection diesel engine, where fuel was supplied to the space between the pistons shortly before the moment when they reached maximum convergence. Moreover, the injection was carried out by four nozzles along a tricky trajectory to ensure instant mixture formation.
But even this is not enough. The engine had a turbocharger with a twist - a huge turbine and compressor were placed on the shaft and had a mechanical connection with one of the crankshafts. Ingenious - in the acceleration mode, the compressor was twisted from the crankshaft, which excluded the turbo lag, and when the exhaust gas flow properly spun the turbine, the power from it was transferred to the crankshaft, increasing the efficiency of the motor (such a turbine is called a power turbine).
In addition, the engine was multi-fuel, that is, it could run on diesel fuel, kerosene, aviation fuel, gasoline, or any mixture of them.
Plus, there are fifty more unusual features, such as composite pistons with heat-resistant steel inserts and a dry sump lubrication system, like in racing cars.
All tricks pursued two goals: to make the motor as compact, economical and powerful as possible. All three parameters are important for a tank: the first facilitates layout, the second improves autonomy, and the third improves maneuverability.
And the result was impressive: with a working volume of 13.6 liters in the most forced version, the engine developed more than 1000 hp. For a diesel engine of the 60s, this was an excellent result. In terms of specific liter and overall power, the engine was several times superior to analogues of other armies. I saw it live, and the layout is really amazing - the nickname "Suitcase" suits him very well. I would even say "a tightly packed suitcase."
It did not take root due to excessive complexity and high cost. Against the background of 5TDF, any car engine - even from the Bugatti Veyron - seems somehow utterly banal. And what the hell is not joking, the technology can make a revolution and again return to the solutions once used on the 5TDF: a two-stroke diesel cycle, power turbines, multi-injector injection.
A massive return to turbo engines has begun, which at one time were considered too complicated for non-sports cars ...
Counter-piston engine- the configuration of the internal combustion engine with the arrangement of pistons in two rows one opposite the other in common cylinders in such a way that the pistons of each cylinder move towards each other and form a common combustion chamber. The crankshafts are mechanically synchronized, and the exhaust shaft rotates ahead of the intake shaft by 15-22 °, power is taken either from one of them or from both (for example, when driving two propellers or two clutches). The layout automatically provides direct-flow scavenging - the most perfect for a two-stroke machine and the absence of a gas joint.
There is another name for this type of engine - counter-moving piston engine (engine with PDP).
The device of the engine with the oncoming movement of the pistons:
1 - inlet pipe; 2 - supercharger; 3 - air duct; 4 - safety valve; 5 - graduation KShM; 6 - inlet KShM (late by ~ 20° from the outlet); 7 - cylinder with inlet and outlet windows; 8 - release; 9 - water cooling jacket; 10 - spark plug. isometryIt would not be an exaggeration to say that most self-propelled devices today are equipped with internal combustion engines of various designs, using various operating principles. In any case, if we talk about road transport. In this article, we will take a closer look at ICE. What it is, how this unit works, what are its pros and cons, you will learn by reading it.
The principle of operation of internal combustion engines
The main principle of operation of an internal combustion engine is based on the fact that fuel (solid, liquid or gaseous) burns in a specially allocated working volume inside the unit itself, converting thermal energy into mechanical energy.
The working mixture entering the cylinders of such an engine is compressed. After its ignition, with the help of special devices, an excess pressure of gases arises, forcing the pistons of the cylinders to return to their original position. This creates a constant working cycle that converts kinetic energy into torque with the help of special mechanisms.
To date, the ICE device can have three main types:
- often called easy;
- four-stroke power unit, allowing to achieve higher power and efficiency values;
- with enhanced power characteristics.
In addition, there are other modifications of the main circuits that improve certain properties of power plants of this type.
Benefits of internal combustion engines
Unlike power units that provide for the presence of external chambers, the internal combustion engine has significant advantages. The main ones are:
- much more compact dimensions;
- higher power ratings;
- optimal efficiency values.
It should be noted, speaking of an internal combustion engine, that this is a device that in the vast majority of cases allows the use of various types of fuel. It can be gasoline, diesel fuel, natural or kerosene, and even ordinary wood.
Such versatility has given this engine concept its well-deserved popularity, ubiquity and truly world leadership.
Brief historical excursion
It is generally accepted that the internal combustion engine has been counting its history since the creation by the Frenchman de Rivas in 1807 of a piston unit that used hydrogen in a gaseous state of aggregation as fuel. And although since then the ICE device has undergone significant changes and modifications, the main ideas of this invention continue to be used today.
The first four-stroke internal combustion engine saw the light in 1876 in Germany. In the mid-80s of the XIX century, a carburetor was developed in Russia, which made it possible to dose the supply of gasoline to the engine cylinders.
And at the very end of the century before last, the famous German engineer proposed the idea of igniting a combustible mixture under pressure, which significantly increased the power characteristics of internal combustion engines and the efficiency indicators of units of this type, which had previously left much to be desired. Since then, the development of internal combustion engines has been mainly along the path of improvement, modernization and the introduction of various improvements.
The main types and types of internal combustion engines
Nevertheless, more than 100 years of history of this type of units has made it possible to develop several main types of power plants with internal combustion of fuel. They differ from each other not only in the composition of the working mixture used, but also in design features.
Gasoline engines
As the name implies, the units of this group use various types of gasoline as fuel.
In turn, such power plants are usually divided into two large groups:
- Carburetor. In such devices, the fuel mixture is enriched with air masses in a special device (carburetor) before entering the cylinders. Then it is ignited by an electric spark. Among the most prominent representatives of this type are the VAZ models, the internal combustion engine of which for a very long time was exclusively of the carburetor type.
- Injection. This is a more complex system in which fuel is injected into the cylinders through a special manifold and injectors. It can occur both mechanically and through a special electronic device. Common Rail direct injection systems are considered the most productive. Installed on almost all modern cars.
Injected gasoline engines are considered to be more economical and provide higher efficiency. However, the cost of such units is much higher, and maintenance and operation are much more difficult.
Diesel engines
At the dawn of the existence of units of this type, one could very often hear a joke about the internal combustion engine, that this is a device that eats gasoline like a horse, but moves much more slowly. With the invention of the diesel engine, this joke has partially lost its relevance. Mainly because diesel is able to run on much lower quality fuel. This means that it is much cheaper than gasoline.
The main fundamental difference between internal combustion is the absence of forced ignition of the fuel mixture. Diesel fuel is injected into the cylinders by special injectors, and individual drops of fuel are ignited due to the pressure force of the piston. Along with the advantages, the diesel engine has a number of disadvantages. Among them are the following:
- much less power compared to gasoline power plants;
- large dimensions and weight characteristics;
- difficulties with starting under extreme weather and climatic conditions;
- insufficient traction and a tendency to unjustified power losses, especially at relatively high speeds.
In addition, repairing a diesel-type internal combustion engine is usually much more complicated and costly than adjusting or restoring the performance of a gasoline unit.
gas engines
Despite the cheapness of natural gas used as fuel, the construction of gas-fired internal combustion engines is incommensurably more complicated, which leads to a significant increase in the cost of the unit as a whole, its installation and operation in particular.
On power plants of this type, liquefied or natural gas enters the cylinders through a system of special gearboxes, manifolds and nozzles. The ignition of the fuel mixture occurs in the same way as in carburetor gasoline installations - with the help of an electric spark emanating from a spark plug.
Combined types of internal combustion engines
Few people know about combined ICE systems. What is it and where is it applied?
This, of course, is not about modern hybrid cars that can run both on fuel and on an electric motor. Combined internal combustion engines are usually called such units that combine elements of various principles of fuel systems. The most prominent representative of the family of such engines are gas-diesel plants. In them, the fuel mixture enters the internal combustion engine block in almost the same way as in gas units. But the fuel is ignited not with the help of an electric discharge from a candle, but with an ignition portion of diesel fuel, as happens in a conventional diesel engine.
Maintenance and repair of internal combustion engines
Despite a fairly wide variety of modifications, all internal combustion engines have similar basic designs and diagrams. Nevertheless, in order to carry out high-quality maintenance and repair of internal combustion engines, it is necessary to thoroughly know its structure, understand the principles of operation and be able to identify problems. To do this, of course, it is necessary to carefully study the design of internal combustion engines of various types, to understand for yourself the purpose of certain parts, assemblies, mechanisms and systems. This is not easy, but very exciting! And most importantly, necessary.
Especially for inquisitive minds who want to independently comprehend all the mysteries and secrets of almost any vehicle, an approximate schematic diagram of an internal combustion engine is presented in the photo above.
So, we found out what this power unit is.
National University of Shipbuilding
them. adm. Makarova
Department of ICE
Abstract of lectures on the course of the internal combustion engine (sdvs) Nikolaev - 2014
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Topic 1. Comparison of internal combustion engines with other types of heat engines. ICE classification. The scope of their application, prospects and directions for further development. The ratio in the internal combustion engine and their marking…………………………………………………… | ||
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Theme. 2 The principle of operation of a four-stroke and two-stroke engine with and without supercharging……………………………………………….. | ||
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Topic 3. Basic design schemes of different types of internal combustion engines. Structural schemes of the engine frame. Elements of the skeleton of the engine. Appointment. The general structure and scheme of interaction of the elements of the crankshaft engine of the internal combustion engine………………………………………... | ||
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Topic 4. ICE systems…………………………………………………... | ||
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Topic 5. Ideal cycle assumptions, processes and cycle parameters. Parameters of the working body in the characteristic places of the cycle. Comparison of different ideal cycles. Conditions for the flow of processes in the calculated and actual cycles…………… | ||
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Topic 6. The process of filling the cylinder with air. The process of compression, conditions of passage, the degree of compression and its choice, the parameters of the working fluid during compression…………………………………….. | ||
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Topic 7. combustion process. Conditions for the release and use of heat during the combustion of fuel. The amount of air needed to burn the fuel. Factors influencing these processes. expansion process. Working body parameters at the end of the process. Process work. Exhaust gas release process……………………………………………………. | ||
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Topic 8. Indicator and effective indicators of engine operation. | ||
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Topic 9. ICE supercharging as a way to improve technical and economic performance. Boost schemes. Features of the working process of a supercharged engine. Ways to use the energy of exhaust gases……………………………………………………... | ||
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Literature……………………………………………………………… | ||
Topic 1. Comparison of internal combustion engines with other types of heat engines. ICE classification. The scope of their application, prospects and directions for further development. The ratio in internal combustion engines and their marking.
Internal combustion engine- this is a heat engine in which the thermal energy released during the combustion of fuel in the working cylinder is converted into mechanical work. The conversion of thermal energy into mechanical energy is carried out by transferring the expansion energy of the combustion products to the piston, the reciprocating motion of which, in turn, through the crank mechanism is converted into rotational motion of the crankshaft, which drives the propeller, electric generator, pump or other consumer energy.
ICE can be classified according to the following main features:
– by type of work cycle- with the supply of heat to the working fluid at a constant volume, with the supply of heat at a constant pressure of gases and with a mixed supply of heat, i.e., first at a constant volume, and then at a constant pressure of gases;
– according to the method of implementation of the working cycle- four-stroke, in which the cycle is completed in four successive piston strokes (for two revolutions of the crankshaft), and two-stroke, in which the cycle is carried out in two successive piston strokes (per one revolution of the crankshaft);
– by way of air supply- with and without boost. In naturally aspirated four-stroke internal combustion engines, the cylinder is filled with a fresh charge (air or combustible mixture) by the suction stroke of the piston, and in two-stroke internal combustion engines, it is filled with a scavenging compressor mechanically driven by the engine. In all supercharged internal combustion engines, the filling of the cylinder is carried out by a special compressor. Supercharged engines are often called combined engines, since in addition to a piston engine they also have a compressor that supplies air to the engine at high pressure;
– according to the method of fuel ignition- compression ignition (diesels) and spark ignition (carburetor to gas);
– by type of fuel used- liquid fuels and gas. Liquid fuel internal combustion engines also include multi-fuel engines that can operate on various fuels without structural changes. Gas internal combustion engines also include compression ignition engines, in which the main fuel is gaseous, and liquid fuel is used in small quantities as a pilot, i.e., for ignition;
– according to the method of mixing- with internal mixing, when the air-fuel mixture is formed inside the cylinder (diesels), and with external mixing, when this mixture is prepared before it is fed into the working cylinder (carburetor and gas engines with spark ignition). The main methods of internal mixture formation - volumetric, volumetric-film and film ;
– by type of combustion chamber (CC)- with undivided single-cavity CVs, with semi-separated CVs (CV in the piston) and separated CVs (pre-chamber, vortex-chamber and air-chamber CVs);
– according to the frequency of rotation of the crankshaft n - low-speed (MOD) with n up to 240 min -1 , medium-speed (SOD) from 240< n
< 750 мин -1 ,
повышенной оборотности (ПОД) с 750
– by appointment- main, designed to drive ship propellers (propellers), and auxiliary, setting in motion electric generators of ship power plants or ship mechanisms;
– according to the principle of action- single action (the work cycle takes place in only one cavity of the cylinder), double action (the work cycle takes place in two cylinder cavities above and below the piston) and with oppositely moving pistons (in each cylinder of the engine there are two mechanically connected pistons moving in opposite directions, with a working body placed between them);
– according to the design of the crank mechanism (KShM)- trunk and crosshead. In a trunk engine, the normal pressure forces that occur when the connecting rod is tilted are transmitted by the guiding part of the piston - the trunk sliding in the cylinder sleeve; in a crosshead engine, the piston does not create normal pressure forces that occur when the connecting rod is tilted, the normal force is created in the crosshead connection and transmitted by sliders to parallels that are fixed outside the cylinder on the engine frame;
– according to the location of the cylinders- vertical, horizontal, single-row, double-row, U-shaped, star-shaped, etc.
The main definitions that apply to all internal combustion engines are:
– upper and bottom dead center (TDC and BDC), corresponding to the upper and lower extreme position of the piston in the cylinder (in a vertical engine);
– stroke, i.e., the distance when the piston moves from one extreme position to another;
– combustion chamber volume(or compression), corresponding to the volume of the cylinder cavity when the piston is at TDC;
– cylinder displacement, which is described by the piston during its course between dead points.
Diesel brand gives an idea of its type and main dimensions. The marking of domestic diesel engines is carried out in accordance with GOST 4393-82 “Stationary, marine, diesel and industrial diesel engines. Types and basic parameters. For marking, symbols are accepted, consisting of letters and numbers:
H- four-stroke;
D- two-stroke;
DD- two-stroke double action;
R- reversible;
FROM– with reversible clutch;
P- with reduction gear;
To- crosshead;
G– gas;
H- supercharged;
1A, 2A, ZA, 4A– degree of automation according to GOST 14228-80.
The absence of a letter in the symbol To means that the diesel trunk, the letters R- the diesel engine is non-reversible, and the letters H- naturally aspirated diesel. The numbers in the brand before the letters indicate the number of cylinders, and after the letters: the number in the numerator is the cylinder diameter in centimeters, in the denominator is the piston stroke in centimeters.
In a diesel brand with oppositely moving pistons, both piston strokes are indicated, connected by a plus sign, if the strokes are different, or the product of “2 per stroke of one piston” if the strokes are equal.
In the brand of marine diesel engines of the production association "Bryansk Machine-Building Plant" (PO BMZ), the modification number is additionally indicated, starting from the second. This number is given at the end of the marking in accordance with GOST 4393-82. Below are examples of markings for some engines.
12CHNSP1A 18/20- diesel twelve-cylinder, four-stroke, supercharged, with a reversible clutch, with a reduction gear, automated according to the 1st degree of automation, with a cylinder diameter of 18 cm and a piston stroke of 20 cm.
16DPN 23/2 X 30- diesel sixteen-cylinder, two-stroke, with gear transmission, supercharged, with a cylinder diameter of 23 cm and with two oppositely moving pistons, each having a stroke of 30 cm,
9DKRN 80/160-4- diesel nine-cylinder, two-stroke, crosshead, reversible, supercharged, with a cylinder diameter of 80 cm, a piston stroke of 160 cm, the fourth modification.
At some domestic plants, in addition to the brand obligatory according to GOST, the manufactured diesel engines are also assigned a factory brand. For example, brand name G-74 (plant "Dvigatel Revolyutsii") corresponds to brand 6CHN 36/45.
In most foreign countries, engine marking is not regulated by standards, and builders use their own naming conventions. But even the same company often changes the accepted designations. Nevertheless, it should be noted that many companies in the symbols indicate the main dimensions of the engine: cylinder diameter and piston stroke.
Theme. 2 The principle of operation of a four-stroke and two-stroke engine with and without supercharging.
Four stroke engine.
Four-stroke internal combustion engine In fig. 2.1 shows a diagram of the operation of a naturally aspirated four-stroke trunk diesel engine (four-stroke crosshead-type engines are not built at all).
Rice. 2.1. The principle of operation of a four-stroke internal combustion engine
1st measure – inlet or filling . Piston 1 moves from TDC to BDC. With a downward stroke of the piston through the inlet pipe 3 and inlet valve located in the cover 2 air enters the cylinder, since the pressure in the cylinder, due to an increase in the volume of the cylinder, becomes lower than the air pressure (or the working mixture in the carburetor engine) in front of the inlet pipe p o. The intake valve opens slightly before TDC (point r), i.e., with a lead angle of 20 ... 50 ° to TDC, which creates more favorable conditions for air to enter at the beginning of filling. The intake valve closes after BDC (point a"), since at the moment the piston arrives at BDC (point a) the gas pressure in the cylinder is even lower than in the inlet pipe. The flow of air into the working cylinder during this period is also facilitated by the inertial overpressure of air entering the cylinder. Therefore, the inlet valve closes with a delay angle of 20 ... 45 ° after BDC.
The lead and lag angles are determined empirically. The angle of rotation of the crankshaft (PKV), corresponding to the entire filling process, is approximately 220 ... 275 ° PKV.
A distinctive feature of a supercharged diesel engine is that during the 1st stroke, a fresh charge of air is not sucked in from the environment, but enters the inlet pipe at elevated pressure from a special compressor. In modern marine diesel engines, the compressor is driven by a gas turbine that runs on engine exhaust gases. The unit consisting of a gas turbine and a compressor is called a turbocharger. In supercharged diesel engines, the filling line usually goes above the exhaust line (4th stroke).
2nd measure – compression . When the piston moves back to TDC from the moment the intake valve closes, the fresh air charge entering the cylinder is compressed, as a result of which its temperature rises to the level necessary for self-ignition of the fuel. Fuel is injected into the cylinder by a nozzle 4 with some advance to TDC (point n) at high pressure, providing high-quality fuel atomization. Fuel injection advance to TDC is necessary to prepare it for self-ignition at the moment the piston arrives at TDC. In this case, the most favorable conditions for the operation of a diesel engine with high efficiency are created. The injection angle in the nominal mode in the MOD is usually 1 ... 9 °, and in the SOD - 8 ... 16 ° to TDC. Flash point (point With) in the figure is shown at TDC, however, it can also be slightly shifted relative to TDC, i.e., fuel ignition may begin earlier or later than TDC.
3rd measure – combustion and extension (work stroke). The piston moves from TDC to BDC. Atomized fuel mixed with hot air ignites and burns, resulting in a sharp increase in gas pressure (point z), and then their expansion begins. The gases, acting on the piston during the working stroke, perform useful work, which is transferred to the energy consumer through the crank mechanism. The expansion process ends when the exhaust valve begins to open. 5 (dot b’ ), which occurs with a lead of 20...40°. Some decrease in the useful work of gas expansion compared to when the valve would open at BDC is offset by a decrease in the work expended on the next cycle.
4th measure – release . The piston moves from BDC to TDC, pushing exhaust gases out of the cylinder. The pressure of the gases in the cylinder at the moment is slightly higher than the pressure after the exhaust valve. In order to completely remove the exhaust gases from the cylinder, the exhaust valve closes after the piston has passed TDC, while the closing lag angle is 10 ... 60 ° PKV. Therefore, during the time corresponding to the angle of 30 ... 110 ° PKV, the inlet and outlet valves are simultaneously open. This improves the process of cleaning the combustion chamber from exhaust gases, especially in supercharged diesel engines, since the charge air pressure in this period is higher than the exhaust gas pressure.
Thus, the exhaust valve is open in the period corresponding to 210...280° PCV.
The principle of operation of a four-stroke carburetor engine differs from a diesel engine in that the working mixture - fuel and air - is prepared outside the cylinder (in the carburetor) and enters the cylinder during the 1st cycle; the mixture is ignited in the TDC region by an electric spark.
The useful work received during the periods of the 2nd and 3rd cycles is determined by the area aWithzba(area with oblique hatching, cm, 4th bar). But during the 1st stroke, the engine expends work (taking into account the atmospheric pressure p o under the piston) equal to the area above the curve r" ma to the horizontal line corresponding to the pressure p o. During the 4th stroke, the engine expends work on pushing out exhaust gases equal to the area under the curve brr "to the horizontal line p o. Therefore, in a four-stroke naturally aspirated engine, the work of the so-called "pumping" strokes, i.e. -th stroke, when the engine acts as a pump, is negative (this work on the indicator diagram is shown by an area with vertical hatching) and must be subtracted from the useful work, equal to the difference between the work in the period of the 3rd and 2nd cycles. In real conditions, the work pump strokes is very small, and therefore this work is conditionally referred to as mechanical losses. In supercharged diesel engines, if the pressure of the charge air entering the cylinder is higher than the average pressure of the gases in the cylinder during the period of their expulsion by the piston, the work of the pump strokes becomes positive.
Two-stroke ICE.
In two-stroke engines, the cleaning of the working cylinder from combustion products and filling it with a fresh charge, i.e., gas exchange processes, occur only during the period when the piston is in the BDC area with open gas exchange organs. In this case, the cleaning of the cylinder from exhaust gases is carried out not by a piston, but by pre-compressed air (in diesel engines) or a combustible mixture (in carburetor and gas engines). Preliminary compression of air or mixture takes place in a special purge or supercharger compressor. During gas exchange in two-stroke engines, some of the fresh charge is inevitably removed from the cylinder along with the exhaust gases through the exhaust organs. Therefore, the supply of the scavenge or boost compressor must be sufficient to compensate for this charge leakage.
The release of gases from the cylinder occurs through windows or through a valve (the number of valves can be from 1 to 4). The intake (purging) of a fresh charge into the cylinder in modern engines is carried out only through the windows. Exhaust and purge windows are located in the lower part of the sleeve of the working cylinder, and the exhaust valves are located in the cylinder cover.
The scheme of operation of a two-stroke diesel engine with loop purge, i.e. when exhaust and purge occur through windows, is shown in fig. 2.2. The work cycle has two cycles.
1st measure- piston stroke from BDC (point m) to TDC. Piston first 6 covers purge windows 1 (point d"), thereby stopping the flow of fresh charge into the working cylinder, and then the piston also closes the outlet windows 5 (dot b" ), after which the process of air compression in the cylinder begins, which ends when the piston reaches TDC (point With). Dot n corresponds to the moment of the beginning of fuel injection by the injector 3 into the cylinder. Consequently, during the 1st stroke, the cylinder ends release , purge and filling cylinder, after which fresh charge compression and fuel injection starts .
Rice. 2.2. The principle of operation of a two-stroke internal combustion engine
2nd measure- piston stroke from TDC to BDC. In the TDC region, the nozzle injects fuel, which ignites and burns out, while the gas pressure reaches its maximum value (point z) and their expansion begins. The gas expansion process ends at the moment the piston starts to open 6 outlet windows 5 (dot b), after which the release of exhaust gases from the cylinder begins due to the difference in gas pressure in the cylinder and the exhaust manifold 4 . The piston then opens the purge windows 1 (dot d) and the cylinder is purged and filled with a fresh charge. Purge will begin only after the gas pressure in the cylinder drops below the air pressure p s in the purge receiver 2 .
Thus, during the 2nd stroke in the cylinder, fuel injection , his combustion , gas expansion , exhaust gases , purge and filling with fresh charge . During this cycle, working stroke providing useful work.
The indicator diagram shown in fig. 2 is the same for both naturally aspirated and supercharged diesel engines. The useful work of the cycle is determined by the area of the diagram md" b"Withzbdm.
The work of gases in the cylinder is positive during the 2nd stroke and negative during the 1st stroke.
The invention can be used in engine building. The internal combustion engine includes at least one cylinder module. The module contains a shaft having a first cam with multiple lobes axially mounted on the shaft, a second adjacent cam with multiple lobes and a differential gear to the first cam with multiple lobes for rotation around the axis in the opposite direction around the shaft. The cylinders of each pair are diametrically opposed to the cam shaft. Pistons in a pair of cylinders are rigidly interconnected. Multi-lobed cams have 3+n lobes, where n is zero or an even integer. The reciprocating motion of the pistons in the cylinders imparts rotational motion to the shaft through the connection between the pistons and the cam surfaces with multiple lobes. The technical result consists in improving the torque and characteristics of the engine cycle control. 13 w.p. f-ly, 8 ill.
The invention relates to internal combustion engines. In particular, the invention relates to internal combustion engines with improved management of various cycles during engine operation. The invention also relates to internal combustion engines with higher torque characteristics. Internal combustion engines that are used in automobiles are typically reciprocating engines in which a piston oscillating in a cylinder drives a crankshaft through a connecting rod. There are numerous shortcomings in the traditional piston engine design with a crank mechanism, the shortcomings are mainly related to the reciprocating movement of the piston and connecting rod. Numerous engine designs have been developed to overcome the limitations and disadvantages of conventional crankshaft internal combustion engines. These developments include rotary engines such as the Wankel engine and engines that use a cam or cams in place of at least a crankshaft and in some cases also a connecting rod. Internal combustion engines in which a cam or cams replace the crankshaft are described, for example, in Australian Patent Application No. 17897/76. However, while advances in this type of engine have made it possible to overcome some of the shortcomings of traditional piston crank engines, engines using a cam or cams instead of a crankshaft are not in full operation. There are also known cases of using internal combustion engines having oppositely moving interconnected pistons. A description of such a device is given in Australian patent application N 36206/84. However, neither this disclosure nor similar documents suggest the possibility of using the concept of oppositely moving interlocking pistons in conjunction with something other than a crankshaft. The object of the invention is to provide a cam rotary type internal combustion engine that can have improved torque and higher engine cycling performance. It is also an object of the invention to provide an internal combustion engine which makes it possible to overcome at least some of the disadvantages of existing internal combustion engines. In a broad sense, the invention provides an internal combustion engine including at least one cylinder module, said cylinder module comprising: - a shaft having a first multi-lobed cam axially mounted on the shaft and a second adjacent multi-lobed cam and a differential gear train to the first cam with multiple lobes for rotation around an axis in the opposite direction around the shaft; - at least one pair of cylinders, the cylinders of each pair are located diametrically opposite to the shaft with cams with several working ledges that are inserted between them; - a piston in each cylinder, the pistons in a pair of cylinders are rigidly interconnected; wherein the multi-lobed cams comprise 3+n lobes, where n is zero or an even integer; and wherein the reciprocating motion of the pistons in the cylinders imparts rotational motion to the shaft via a linkage between the pistons and the multi-lobed cam surfaces. The engine can contain from 2 to 6 cylinder modules and two pairs of cylinders for each cylinder module. Pairs of cylinders can be arranged at an angle of 90 o to each other. Advantageously, each cam has three lobes and each cam is asymmetrical. The rigid interconnection of the pistons includes four connecting rods passing between a pair of pistons with the connecting rods being at the same distance from each other along the periphery of the piston, and guide bushings are provided for the connecting rods. The differential gear train can be mounted inside the motor with reverse cams or on the outside of the motor. The engine may be a two-stroke engine. In addition, the connection between the pistons and the surfaces of the cams with multiple lobes is through roller bearings, which may have a common axis, or their axes may be offset relative to each other and the axis of the piston. It follows from the above that the crankshaft and connecting rods of a traditional internal combustion engine are replaced by a linear shaft and cams with multiple lobes in the engine in accordance with the invention. The use of a cam instead of a connecting rod/crankshaft arrangement allows greater control over piston positioning during engine operation. For example, the period the piston is at top dead center (TDC) can be extended. It follows from the detailed description of the invention that despite the presence of two cylinders in at least one pair of cylinders, a double-acting cylinder-piston arrangement is actually created by means of oppositely located cylinders with interconnected pistons. The rigid interconnection of the pistons also eliminates skew torsion and minimizes contact between the cylinder wall and the piston, thus reducing friction. The use of two counter-rotating cams makes it possible to achieve higher torque than with traditional internal combustion engines. This is because as soon as the piston starts its power stroke, it has the maximum mechanical advantage in relation to the cam lobe. Turning now to more specific details of internal combustion engines in accordance with the invention, such engines, as indicated above, include at least one cylinder module. An engine with one cylinder module is preferred, although engines can have two to six modules. In motors with multiple modules, a single shaft passes through all the modules, either as a single element or as interconnected shaft parts. Likewise, cylinder blocks of multi-module engines may be integral with each other or separately. A cylinder module usually has one pair of cylinders. However, engines according to the invention may also have two pairs of cylinders per module. In cylinder modules having two pairs of cylinders, the pairs are typically arranged at 90° to each other. With respect to multi-lobed cams in the engines according to the invention, preference is given to a three-lobed cam. This allows six ignition cycles per revolution of the cam in a two-stroke engine. However, engines may also have cams with five, seven, nine or more lobes. The lobe of the cam can be asymmetrical to control the speed of the piston at a certain stage of the cycle, for example, to increase the length of time the piston is at top dead center (TDC) or bottom dead center (BDC). According to those skilled in the art, increasing the time at top dead center (TDC) improves combustion, while increasing the time at bottom dead center (BDC) improves scavenging. The control of the piston speed by means of a work profile also makes it possible to control the piston acceleration and torque application. In particular, this makes it possible to obtain more torque immediately after top dead center than in a conventional piston engine with a crank mechanism. Other design features provided by the variable piston speed include adjusting the opening speed of the orifice versus the closing rate and adjusting the compression rate versus the combustion rate. The first multi-lobed cam may be mounted on the shaft in any manner known in the art. Alternatively, the shaft and the first multi-lobed cam may be manufactured as a single piece. The differential gear train, which enables the reverse rotation of the first and second multilobate cams, also synchronizes the reverse rotation of the cams. The method of differential cam gearing can be any method known in the art. For example, bevel gears may be mounted on opposite surfaces of the first and second multi-lobed cams with at least one gear between them. Preferably, two diametrically opposed gears are mounted. A supporting element in which the shaft rotates freely is provided for the supporting gears, which offers certain advantages. The rigid relationship of the pistons typically includes at least two connecting rods that are installed between them and are attached to the bottom surface of the pistons adjacent to the periphery. Preferably, four connecting rods are used, spaced equally apart along the periphery of the piston. The cylinder module has guide bushings for the connecting rods that interconnect the pistons. Guide bushings are typically configured to allow lateral movement of the connecting rods as the piston expands and contracts. The contact between pistons and cam surfaces helps to reduce vibration and frictional losses. There is a roller bearing on the underside of the piston to make contact with each cam surface. It should be noted that the relationship of the pistons, including a pair of oppositely moving pistons, makes it possible to control the gap between the contact area of the piston (whether it be a roller bearing, bottom bracket, or the like) and the cam surface. Moreover, this method of contact does not require grooves or the like in the cam flanks in order to obtain a traditional connecting rod, as is the case with some similarly designed engines. This characteristic of engines of a similar design leads to wear and excessive noise when overspeeding, these disadvantages are largely eliminated in the present invention. The engines according to the invention may be two-stroke or four-stroke. In the first case, the fuel mixture is usually supercharged. However, any kind of fuel and air supply can be used together in a four-stroke engine. The cylinder modules according to the invention can also serve as air or gas compressors. Other aspects of the engines according to the invention are in accordance with what is generally known in the art. However, it should be noted that only a very low pressure oil supply to the multi-lobed differential cam gear train is required, thus reducing power loss by the oil pump. Moreover, other parts of the engine, including pistons, can receive oil by splashing. In this regard, it should be noted that the spraying of oil on the pistons by means of centrifugal force also serves to cool the pistons. The advantages of the engines according to the invention include the following: the engine has a compact design with few moving parts; - motors can work in any direction when using cams with several symmetrical working ledges; - engines are lighter than traditional piston engines with a crank mechanism; - motors are more easily manufactured and assembled than traditional motors;
- a longer break in the piston, which is made possible by the design of the engine, allows the use of a lower than normal compression ratio;
- eliminated parts with reciprocating motion, such as piston-crank shaft connecting rods. Other advantages of engines according to the invention due to the use of cams with multiple lobes are the following: cams can be more easily manufactured than crankshafts; cams do not require additional counterweights; and the cams double the action as a flywheel, thus providing more movement. Having considered the invention in a broad sense, we now give specific examples of the invention with reference to the accompanying drawings, briefly described below. Fig. 1. Cross section of a two-stroke engine, which includes one cylinder module with a cross section along the axis of the cylinders and a cross section with respect to the engine shaft. Fig. 2. Part of the cross section along the line A-A of FIG. 1. FIG. 3. Part of the cross section along the line B-B of FIG. 1 showing a detail of the bottom of the piston. Fig. 4. Graph showing the position of a specific point on the piston when crossing one asymmetrical cam lobe. Fig. 5. Part of a cross section of another two-stroke engine including one cylinder module with a cross section in the plane of the engine's central shaft. Fig. 6 is an end view of one of the gear sets of the engine shown in FIG. 5. FIG. 7. Schematic view of a portion of an engine showing a piston in contact with three lobe lobes that rotate in the reverse direction. Fig. 8. Detail of a piston having bearings in contact with an offset cam. Identical positions in the figures are numbered identically. In FIG. 1 shows a two-stroke engine 1 comprising one cylinder module which has one pair of cylinders consisting of cylinders 2 and 3. Cylinders 2 and 3 have pistons 4 and 5 which are interconnected by four connecting rods, two of which are visible at positions 6a and 6b . The engine 1 also includes a central shaft 7 to which are connected cams with three lobes. Cam 9 actually coincides with cam 8 as shown in the figure due to the fact that the pistons are at top dead center or bottom dead center. Pistons 4 and 5 contact cams 8 and 9 through roller bearings, the position of which is generally indicated at positions 10 and 11. Other design features of engine 1 include a water jacket 12, spark plugs 13 and 14, oil sump 15, sensor 16 oil pump and balance shafts 17 and 18. The location of the intake ports is indicated by positions 19 and 20, which also corresponds to the position of the exhaust ports. In FIG. 2 shows the cams 8 and 9 in more detail, together with the shaft 7 and the differential gear train, which will be briefly described. The cross section shown in Fig. 2 rotated 90° with respect to FIG. 1 and the cam lobes are in a slightly different position compared to the positions shown in FIG. 1. The differential or timing gear train includes a bevel gear 21 on the first cam 8, a bevel gear 22 on the second cam 9, and drive gears 23 and 24. The drive gears 23 and 24 are supported by a gear support 25 that is attached to the shaft housing 26 . Shaft housing 26 is preferably part of a cylinder module. In FIG. 2 also shows the flywheel 27, pulley 28 and bearings 29-35. The first cam 8 is generally made in one piece with the shaft 7. The second cam 9 can rotate in the opposite direction with respect to the cam 8, but is controlled in time to the rotation of the cam 8 by a differential gear. In FIG. 3 shows the underside of the piston 5 shown in FIG. 1 to introduce the detail of roller bearings. In FIG. 3 shows piston 5 and shaft 36 extending between bosses 37 and 38. Roller bearings 39 and 40 are mounted on shaft 36 which correspond to the roller bearings as indicated by numbers 10 and 11 in FIG. 1. The interconnected connecting rods can be seen in cross section in FIG. 3, one of them is indicated by 6a. Couplings are shown through which interconnected connecting rods pass, one of which is indicated by the number 41. Although FIG. 3 is shown on a larger scale than FIG. 2, it follows that roller bearings 39 and 40 may come into contact with surfaces 42 and 43 of cams 8 and 9 (FIG. 2) during engine operation. The performance of the engine 1 can be estimated from FIG. 1. The movement of pistons 4 and 5 from left to right during the power stroke in cylinder 2 causes the rotation of cams 8 and 9 through their contact with the roller bearing 10. The result is the effect of "scissors". The rotation of the cam 8 affects the rotation of the shaft 7, while the reverse rotation of the cam 9 also contributes to the rotation of the cam 7 by means of a differential gear (see Fig. 2). Thanks to the scissor action, more torque is achieved during the power stroke than in a traditional engine. Indeed, the piston diameter/stroke ratio shown in FIG. 1 can aim for a much larger configuration area while maintaining adequate torque. Another design feature of the engines according to the invention, shown in FIG. 1 is that the equivalent crankcase is sealed against the cylinders, unlike conventional two-stroke engines. This makes it possible to use fuel without oil, thus reducing the components emitted by the engine into the air. Piston speed control and duration at top dead center (TDC) and bottom dead center (BDC) when using an asymmetrical cam lobe are shown in FIG. 4. FIG. 4 is a plot of a particular point on the piston as it oscillates between midpoint 45, top dead center (TDC) 46 and bottom dead center (BDC) 47. Due to the cam's asymmetrical cam lobe, the speed of the piston can be adjusted. First, the piston is at top dead center 46 for a longer period of time. The rapid acceleration of the piston at position 48 allows for higher torque during the combustion stroke, while the slower piston speed at position 49 at the end of the combustion stroke allows for more efficient orifice control. On the other hand, a higher piston speed at the beginning of the compression stroke 50 allows faster closing for improved fuel economy, while a low piston speed at the end 51 of this stroke provides higher mechanical benefits. In FIG. 5 shows another two-stroke engine having a single-cylinder module. The engine is shown in partial cross section. In fact, half of the engine block has been removed to show the inside of the engine. The cross section is a plane coinciding with the axis of the central shaft of the motor (see below). Thus, the engine block is divided along the center line. However, some engine components are also shown in cross section, such as pistons 62 and 63 bearing bosses 66 and 70, triple lobe cams 60 and 61, and bushing 83 associated with cam 61. All of these positions will be discussed below. Engine 52 (FIG. 5) includes block 53, cylinder heads 54 and 55, and cylinders 56 and 57. A spark plug is included in each cylinder head, but is omitted from the drawing for clarity. Shaft 58 can rotate in block 53 and is supported by roller bearings, one of which is indicated by item 59. The shaft 58 has a first cam 60 with three lobes attached thereto, the cam adjacent to a three lobed cam 61 which rotates in the reverse direction. Engine 52 includes a pair of rigidly interconnected pistons 62 in cylinder 56 and 63 in cylinder 57. Pistons 62 and 63 are connected by four connecting rods, two of which are indicated at positions 64 and 65. (Connecting rods 64 and 65 are in a different plane with respect to the rest Likewise, the points of contact of the connecting rods and pistons 62 and 63 are not in the same plane of the rest of the cross section.The relationship between the connecting rods and pistons is essentially the same as for the engine shown in Fig. 1 -3). The web 53a extends within the block 53 and includes holes through which the connecting rods pass. This bridge keeps the connecting rods and therefore the pistons in line with the axis of the cylinder module. Roller bearings are inserted between the undersides of the pistons and the surfaces of the cams with three lobes. As for the piston 62, a bearing boss 66 is mounted on the underside of the piston, which supports the shaft 67 for the roller bearings 68 and 69. The bearing 68 contacts the cam 60 while the bearing 69 contacts the cam 61. Preferably, the piston 63 includes itself identical bearing boss 70 with a shaft and bearings. It should also be noted, in view of the carrier boss 70, that the web 53b has an appropriate opening to allow the carrier boss to pass through. Jumper 53a has a similar hole, but the part of the jumper shown in the drawing is in the same plane as the connecting rods 64 and 65. Rotation in the opposite direction of the cam 61 with respect to the cam 60 is carried out by a differential gear 71 mounted on the outside of the cylinder block . Housing 72 is provided to hold and cover gear components. In FIG. 5, housing 72 is shown in cross section, while gear train 71 and shaft 58 are not shown in cross section. Gear train 71 includes a sun gear 73 on a shaft 58. Sun gear 73 is in contact with drive gears 74 and 75 which in turn are in contact with planetary gears 76 and 77. Planetary gears 76 and 77 are connected via shafts 78 and 79 to a second set of planetary gears 80 and 81 that are mounted with sun gear 73 on hub 83. Hub 83 is coaxial with shaft 58 and the distal end of the hub is attached to cam 61. Drive gears 74 and 75 are mounted on shafts 84 and 85, the shafts are supported by bearings in housing 72. A portion of gear train 71 is shown in FIG. 6. FIG. 6 is an end view of shaft 58 as viewed from below FIG. 5. In FIG. 6, the sun gear 73 is visible near the shaft 57. The pinion gear 74 is shown in contact with the planetary gear 76 on the shaft 78. The figure also shows the second planetary gear 76 on the shaft 78. The figure also shows the second planetary gear 80 in contact with the sun gear 32 on the shaft 78. sleeve 83. From FIG. 6 that clockwise rotation of, for example, shaft 58 and sun gear 73 has a dynamic effect on counterclockwise rotation of sun gear 82 and bushing 83 through pinion gear 74 and planetary gears 76 and 80. Hence, cams 60 and 61 can rotate in the opposite direction. Other engine design features shown in FIG. 5 and the working principle of the motor are the same as those of the motor shown in FIG. 1 and 2. In particular, the downward thrust of the piston imparts a scissor-like action to the cams, which can result in reverse rotation by means of a differential gear train. It should be emphasized that while in the engine shown in FIG. 5, ordinary gears are used in the differential gear, bevel gear may also be used. Likewise, ordinary gears can be used in the differential gear train shown in FIG. 1 and 2, engine. In the engines exemplified in FIG. 1-3 and 5, the axes of the roller bearings are aligned, which are in contact with the surfaces of the cams with three working ledges. To further improve the torque characteristics, the roller bearing axles can be offset. A motor with an offset cam that is in contact with the bearings is shown schematically in FIG. 7. In this figure, which is a view along the central shaft of the motor, cam 86, reverse-rotating cam 87, and piston 88 are shown. Piston 88 includes bearing bosses 89 and 90 which carry roller bearings 91 and are shown in contact with the lobes 93 and 99 respectively of the triple cams 86 and 87. From FIG. 7 that the axes 95 and 96 of the bearings 91 and 92 are offset with respect to each other and with respect to the axis of the piston. By positioning the bearings at a certain distance from the piston axis, the torque is increased by increasing the mechanical advantage. A detail of another piston with offset bearings on the underside of the piston is shown in FIG. 8. Piston 97 is shown with bearings 98 and 99 housed in housings 100 and 101 on the underside of the piston. It follows that the axes 102 and 103 of the bearings 98 and 99 are misaligned, but not to the same extent as the misaligned bearings in FIG. 7. It follows that the greater separation of the bearings, as shown in FIG. 7, increase torque. The above specific embodiments of the invention relate to two-stroke engines, it should be noted that the general principles apply to two- and four-stroke engines. It is noted below that many changes and modifications can be made to engines as shown in the above examples without departing from the limits and scope of the invention.
