A supercharged internal combustion engine provided with a charging blower, whose outlet is by means of an air intake conduit with a throttle valve connected to the beginning of a charging conduit for supplying air to a combustion chamber of a cylinder/cylinders.

Background art

In contemporary modern piston internal combustion engines, normally about one quarter of the energy supplied by fuel is transformed into mechanical work. This is true for atmospheric engines, wherein combustion air enters the engine at atmospheric pressure. In engines supercharged, for example, by a turbocharger in which combustion air is supplied to the combustion chamber at a pressure greater than atmospheric pressure, efficiency is higher, Whereby the efficiency achieved may be up to 35%. For the sake of clarity, combustion air, in other words, the air taking part in combustion, is hereinafter denoted as supply air.

The first internal combustion engine was designed 150 years ago - it was a four-stroke engine running on petrol. Despite a long period of its existence filled with research and development of the engine and its types, the process of seeking new possibilities is still continuing today with the aim of improving engine components, which would bring optimization of the thermal cycle of the actual internal combustion engine towards the unrealizable limit of efficiency, which is represented by the so-called Carnot cycle. It is characterized by adiabatic compression, which reduces the volume of the air delivered before the ignition mixture is ignited, and adiabatic expansion, which increases the volume of exhaust gases after the ignition of the mixture. Adiabatic process is one that occurs without transfer of heat between the compressed air and its surroundings, as well as between the burning mixture and its surroundings. Accurately adiabatic process is not real. However, it is possible to approach the adiabatic process. The invention aims to increase engine efficiency, that is to increase engine performance and of ofat the same time save fuel, and, of course, not to increase the ecological burden of the environment.

Principle of the invention

The goal of the invention is achieved by a supercharged internal combustion engine comprising at least one cylinder, whose principle consists in that the inner cross-section of the charging conduit decreases in the direction of supply air flow to the combustion chamber, whereupon the charging conduit is connected to an air chamber, to which is/are connected an air channel/air channels, which exit through an insulating body into a charging channel formed in the respective head. The inner cross-section of the air conduit in the direction towards the respective head changes its shape from a circular cross-section into an oval shape before the end of the air conduit and gradually decreases until reaching the minimum cross-section formed in the charging channel downstream of the insulating body. Beyond this minimum cross-section of the charging channel gradually increases up to a cross-section in the vicinity of the inlet to the combustion chamber, and further on becomes a larger cross- section for the seats of intake valves coupled to a cam gear. This larger cross- section can be made up of two circular cross-sections for two seats of the intake valves.

Reduction of the cross-section of the first portion of the charging conduit and subsequent enlargement of this cross-section at the inlet of the air chamber, as well as subsequent reducing of the cross-section of the air conduit and the adjoining charging channel and subsequent enlargement of the cross- section before the valve seats causes the expansions of the supply air during which a multi-stage process of cooling down the air takes place, which is a prerequisite for lowering the engine temperature. This effect is efficiently supported by thermal separation of the engine head from the charging channel by the insulating body. The expansion of the supply air significantly contributes to the atomization and homogenization of the air-fuel mixture.

The charging channel in the insulating body is bent, which makes it easier in terms of design and construction to connect the fuel injector for indirect injection and to ensure that it is optimally directed. The nozzle is directed in the direction of the air flow towards the area of the charging channel, upstream of its minimum cross-section and further on towards the discs of the intake valves, cooling them effectively.

The piston stroke/ cylinder bore ratio is in the range between 0.75 and

0.85. A strong long-stroke engine is a prerequisite for achieving a sufficiently high output for a given cylinder capacity without exceeding the acceptable mean piston speed.

When using direct injection, the nozzle of the injector goes directly into the combustion chamber. The direct or indirect injection modes can be used separately, or they can be combined, whereby the internal combustion engine is simultaneously filled with a mixture of air and fuel prepared perfectly outside the combustion chamber and with fuel injected into the combustion chamber, that is, a part of the mixture formed only in the combustion chamber. This combination of injection modes with an appropriate regulating system, further contributes to increasing the engine efficiency. Another option of using both injection methods is using indirect injection at low engine revolutions and using only direct injection at high revolutions.

The spark plug is made to face with its spark gap the feed of the fuel or fuel-air mixture, the feed being directed to the open space between the spark plug electrodes.

The charging conduit is at its beginning branched into at least two branches forming the first parts of the charging conduit, whereby the lengths of mutually corresponding parts of the entire path of the supply air are equal in all the branches, their volume and pressure being equal as well. This is necessary from the point of view of the combustion chambers of the cylinders of two- and multi-cylinder engines being charged equally both in terms of the same- volume of the mixture as well as in terms of equally good preparation of the mixture.

For supercharging, the engine uses a turbocharger, which is advantageous in terms of economically favourable utilization of exhaust gas energy. An intercooler of the supply air, which is arranged at the outlet of the turbocharger, contributes to the low temperature of the engine. .

4 . _. ..

The circumference of the outlet port of the air chamber to the air conduit is provided with a protrusion directed into the inner space of the air chamber. This solution reduces the resistance against the charging air flowing oyer the edge of the port between the air chamber and the air conduit connected to it and contributes to the high speed of the air flow and the Venturi effect, which is created by the adjoining charging channel.

The combustion chamber in the head is roof shaped, two intake valves and two exhaust valves being arranged opposite each other, wherein the spark gap of the spark plug is arranged in the region of the axis of the cylinder symmetry. This enables to increase the flow area especially of the intake valve seats without the need for a large valve stroke. The central location of the spark gap of the spark plug has a positive influence on the ignition and optimal course of the combustion of the mixture.

At least a part of the inner circumference of the head face is formed by a planar area or flat areas perpendicular to the axis of rotation of the cylinder, to which correspond areas formed along the circumference of the piston face, which are parallel to the planar areas. In this manner, the compression space at top dead centre of the piston is reduced and an optimal compression ratio is achieved, which is preferably in the range between 10,4 : 1 and 11 ,1 : 1.

Assigned to the combustion chamber is an ignition system comprising a control unit with means of regulating the moment of ignition with respect to the position of the crankshaft in the range between at least 8° and 30° before the top dead centre of the piston and with means of controlling fuel injection. That allows to achieve a high engine efficiency with the mixing ratio λ=1 and larger in terms of compliance with the exhaust emission limits.

The space defined by a groove for the piston ring and the inner diameter of the piston ring is connected to the combustion chamber above the piston through channels formed in the piston and evenly distributed along the circumference of the piston. Thus, a suitable contact pressure of the piston rings on the wall of the cylinder is achieved, in terms of the tightness of the combustion chamber, as well as from the point of view of the service life of both the rings and the cylinder surface. The ignition system is coupled to a cam gear comprising a camshaft of intake valves and a camshaft of exhaust valves, whrereby at least one of the camshafts is coupled to a means of adjusting its position relative to the crankshaft position. In this manner, by means of a cam gear actuator, the control unit of the engine changes the engine ^' s timing according to the information about the instantaneous state and the engine needs in conjunction with regulating the moment of ignition and the timings of opening or closing the suction and exhaust valves, which is important both in terms of engine efficiency, its performance and instantaneous consumption of fuel, and in terms of compliance with emission regulations.

The lengths and clear areas of the exhaust gas path from the individual exhaust valves to the turbocharger are mutually identical, which is a prerequisite for the same course of exhaust gas discharge from all cylinders and hence for the same ratios when charging the cylinders with a fresh mixture and, consequently, for the same course of the burning process. This arrangement is, of course, also advantageous from the point of view of the drive of the turbocharger.

Description of drawings

The engine according to the invention, or, more specifically, its components and parts, are shown in the accompanying drawings, which schematically represent in Fig. 1 without a scale a plan view of the main parts of a flat four-cylinder engine with opposed cylinders, in Fig. 2a there is a plan view of a simplified charging conduit having a section whose cutting plane passes through the axis of the charging conduit and the intake conduit, Fig. 2b is an analogical view of a simplified straight air charging conduit of Fig. 2a in P1 direction, Fig. 3a is a cross-sectional view of a simplified air charging conduit of a single-cylinder engine drawn along the plane common to longitudinal axes of the charging conduit and the air conduit before the inlet to the head, Fig. 3b a view in P2 directionof Fig. 3a of a section of a plane passing through the axis of the charging conduit away from the throttle valve. The engine components described in the other figures are common both to a single-cylinder engine and to multi-cylinder engines. Fig. 4 shows a longitudinal off-set section of the head of the internal combustion engine with a part of the cylinder with a piston drawn along the longitudinal axis of the cylinder and the axis of the stems of two valves perpendicular to the axis of the piston pin, Fig. 5 is a bottom view showing the front surface of the combustion chamber in the cylinder head, Fig. 6a is the shape of cross-sections of a part of the charging channel passing through the engine head in the same cross-section as shown in Fig. 4, Fig. 6b is a cross-section of the charging channel along the plane which passes through the axis of the charging channel and is perpedicular to the plane of the cross- section of the charging channel of Fig. 6a, Fig. 7 is a detail view of a intake valve and a cross-section of its seat in the head, Fig. 8a is a view of a longitudinal section through an air chamber of a four-cylinder in-line engine drawn along the plane common to the longitudinal axes of the air conduits, Fig. 8b is a view in P4 direction of Fig. 8a, Fig. 8c is a view in P5 direction of a cross-section B-B of the air chamber of Fig. 8a and finally Fig. 9 is is a section drawn along the axis of the branched charging conduit perpendicularly to the axes of the air conduits of an eight-cylinder V-engine.

Examples of embodiment

The functional parts of the supercharged internal combustion engine according to the invention are dealt with in the following description in succession according to the path of the supply air, or, more precisely, the mixture of fuel with supply air supplied to the engine cylinders. At the beginning of this path is the entrance of the air supplied by a blower, most often by a turbocharger driven by exhaust gases of the engine, or by a blower mechanically coupled to the engine outputshaft.

For illustrative purposes, to explain the relative arrangement of the engine parts with respect to the position of the crankshaft, in an exemplary embodiment in Fig. 1 there is a top view of a flat four-cylinder engine 100 with opposed cylinders, also known under the term "boxer", which will be further described. One common unillustrated crankshaft 102 and unillustrated cylinders 2, 3, 4, 5 are mounted in the engine block 101. The axes of a pair of cylinders 2, 3 on one side of the crankshaft 102 and an opposed pair of cylinders 4, 5 on the other side of the crankshaft 102 lie in a common substantially horizontal plane, in which lies also the axis I of rotation of the crankshaft 102. The heads 21 , 31 of the pair of cylinders 2, 3 on one side of the crankshaft 102 are turned away from the heads 4_1, 5 of the pair of cylinders 4, 5 on the other side of the crankshaft 102. In an exemplary embodiment, the heads 21, 3J. of the two cylinders 2, 3 and the heads 41 , 5_1 of the two cylinders 4, 5 are made as a compact double head.

Above the block 101 of the engine 100 is arranged a charging conduit 6 of air, which is in this engine divided into two branches ( , ( Its beginning 6_10 of charging conduit 6 is connected by a flange 60 to the intake conduit 61 of air supplied from the blower 62. In an embodiment according to the invention, the blower 62 is preferably a turbocharger 621 , which is advantageous from the point of view of economy of the engine. The branch ί of the charging conduit 6 of air is guided to the pair of cylinders 2, 3, the branch 6^ is guided to the pair of cylinders 4, 5. The inner cross-section of both branches of the charging conduit 6 of air is downstream of the branching point substantially circular oyer the entire length, whereby in the direction of the air flow the area of the cross- section of the branch ( , 6_^ decreases gradually and without any sudden transitions virtually down to half the cross-section of the branch immediately beyond the branching point. From the individual cylinders 2, 3, 4, 5 below the block 101 are guided exhaust pipes 22, 32, 42, 52^ which are schematically represented by thin dashed lines. The outlet ends of the exhaust pipes 22, 32, 42, 52 are connected to an inlet to an uniilustrated turbine of the turbocharger 62, whereby the outlet of the exhaust gases exiting from the turbine of the turbocharger 621 is guided to an uniilustrated exhaust system 7 of the engine 100. These exhaust pipes have mutually identical lengths and their flow cross-section has no sharp transitions or edges. The exhaust pipes are guided either individually along the entire length from the heads to a short intake manifold before the turbocharger, or two and two pipes are connected at the same distance before the turbocharger and are further guided in two streams to the turbocharger.

For simplification purposes, the charging conduit 6 in Figs. 2a, 2b is shown as straight. Such a pipe would be ideal with the same length of its branches ( , §T_ in terms of even distribution of the amount of the air fed to the combustion chamber. In the air intake pipe 61 from the turbocharger 621 before the connecting flange 60 is located a known air throttle valve 611 arranged on a rotary axis 612, which is perpendicular to the axis of the air intake pipe 61, intersecting the longitudinal axis of the air intake pipe 61. This position of the throttle valve 611 ensures delivery of the same volume of air supply to both branches ( , < of the charging conduit 6 practically throughout the entire angular displacement of the throttle valve 611. A rectifier 63 of the supply air is provided opposite the mouth of the air intake pipe 61 from the turbocharger 621 in the wall of the charging conduit 6. The rectifier 63 of the supply air, which is formed by a protrusion on at least a part of the inner circumference of the pipe opposite the mouth of the intake pipe 61^ is another means which ensures even distribution of air to both branches of the charging conduit 6. Preferably, the turbocharger 621 delivers air at an absolute pressure of at least 2.6 bar or at least 2.5 bar and more. An unillustrated intercooler of the charging air is arranged, or may be arranged, in the intake pipe 61 between the turbocharger 621 and the inlet to the charging conduit 6.

Each of the branches ( , 6^ of the charging conduit 6 is joined in the vicinity of the pair of heads 21 , 31, or 41_, 51 , by the air chamber 64, or 65,, in which the supply air expands, thereby losing heat. According to Figs. 2a and 2b, the air chamber 64 has two outlet ports 641 , 642, to which are connected air pipes 103 for supplying the supply air to the head 21 of the cylinder 2 and to the head 31 of the cylinder 3. The air chamber 65 has two outlet ports 651 , 652, to which are connected air pipes 103 for supplying air to the head 41 of the cylinder 4 and to the head 51 of the cylinder 5.

The actual air chambers 64, 65 have identical inner shapes. The individual sections through the air chamber 64, 65, whose planes pass through the longitudinal axis 600 of the air chamber, are substantially elliptical. On the other hand, the sections through the air chamber 64, 65, whose planes are perpendicular to the longitudinal axis 600 of the air chamber 64. 65, are substantially circular. The inner surface of the air chambers 64, 65 is fluent from an aerodynamic point of view and basically does not disturb laminar air flow as far as to the area of the outlet ports 641. 642, 651, 652 The single-cylinder internal combustion engine according to the invention differs from a multi-cylinder engine, for example from the four-cylinder engine 100 described above, by a simple charging conduit 6001 of air, which is shown in Figs. 3a and 3b. The charging conduit 6001 also has a circular inner cross- section, which decreases in the direction of the air flow. The air chamber 6401 has a circular shape or, in the illustrated embodiment, an ellipsoid or other oval shape. The air chamber 6401 has only one outlet port 6410, which is joined - analogously to the four-cylinder engine described above - by the air pipe 103.

An embodiment of an in-line internal combustion engine according to the invention is shown in Figs. 8a to 8c using an example of a four-cylinder engine. Its air chamber 6402 is through its inlet flange 6403 connected to a charging conduit 6001, which is analogous to the charging conduit 6001 of a single- cylinder engine shown in Fig.3a, or 3b. In the direction of a row of engine cylinders, the air chamber 6402 has an elongated cross-section, which decreases in the direction downstream of the inlet. The air chamber 6402 is joined through inlet ports 6406 by air pipes 103, whereby their embodiment corresponds to the embodiment of the other types of the engines described. Due to the decreasing cross-section of the air chamber 6402 it is possible to achieve substantially equal pressure ratios at all the inlet ports 6406 to the air pipes 103, which is a prerequisite for equal amounts of air being delivered to each cylinder. The air pipes 103 are further connected to insulating bodies 112 of the cylinder heads shown in a cross-section of Fig. 4.

Fig. 9 shows a diagram of a charging conduit for an eight-cylinder V- engine. Two identical air chambers 6407 for each of the four cylinders of this engine are analogous to the above-mentioned air chamber 6402 of the charging conduit of a four-cylinder in-line engine. The intake pipe 61 of the supply air from the turbocharger is at the beginning 610 divided into two straight branches 6_1, 6_H of the first part of the charging conduit 6 analogously to the flat four- cylinder boxer downstream of the throttle valve 611 and the adjoining flange 60. Elbow pipes 68 constituting the second part of the charging pipe 6 are connected to the ends of the straight branches ( , 6_H by flanges 67. Connected to the elbow pipes 68 by flanges 69 are air chambers 6407 for a pair of heads of the eight-cylinder V-engine. The cross-section of the charging conduit 6 also gradually decreases over the entire length, i.e. over the branch ( , 6_^ and in the area of the adjoining elbow pipe 68, as far as to the inlet to the air chambers 6407.

In the illustrated exemplary embodiment, the inlet portion to the air pipe 103 is inserted into the port 641, 642, 651 , 652, 6406, 6410 of the air chamber 64, 65, 6401 , 6402, 6407 in such a manner that it overlaps its inner surface, whereby the edge of this inner portion is rounded, constituting with respect to the inner surface of the air chamber 64, 65, 6401 6402, 6407 an protrusion 66 shown in Fig. 2b, 3a a 3b. This protrusion 66 directs a thin layer of the flowing air such that on the protrusion 66 radial flow occurs around the outer edge of the port towards the air pipe 103 relative to the circular circumference of the port 641 , 642, 651 , 652, 6406, 6410. Basically, the resulting turbulent flow is desirable only at this point of the flow of the supply air. Turbulent air flow generates turbulent toroidal Jnsert" which increases the flow speed towards the inlet to the air pipe 103.

The inner cross-section of all the air pipes 103 gradually decreases towards the respective heads 21_, 31 , 41 , 51 , whereby the circular hole at the point of the outlet out of the air chamber 64, 65, 6402, 6407, 6410 gradually changes, forming an oval cross-section SJ. already before the outlet flange 104.

Fig. 4 schematically represents off-set section of a four-valve head 21,

31 , 41, 51 according to the invention, which is substantially identical to both a single-cylinder engine and a multi-cylinder engine. The section is drawn along planes perpendicular to the axis of the piston pin 105, namely along the axial plane of the cylinder and along the plane common to the longitudinal axes of the intake valve 106 and the exhaust valve 107. Fig. 5 shows in a view into the roof- shaped combustion space of the head 21 , 31 , 41, 51 the position of two intake valves 106, two exhaust valves 107 and the central position of the spark plug 108. This arrangement of the roof-shaped combustion space of the head enables to use a large diameter of the discs 1Ό9 of the intake valves 106 as well as of the exhaust valves 107 to form a large flow area with open valves. Thus, with a relatively small valve stroke of the intake valve 106 the maximum air flow rate between the disc 109 and the seat 110 of the intake valve 106 is lower than 60% of the speed of sound (Mach index 0.6). The outlet flange 104 of each air pipe 103 is joined by the charging channel 111., the first part of which is formed in the insulating body 112 mounted between the head 21 , 31 , 44, 51 of the cylinder 2, 3, 4, 5 and the respective air pipe 103. The insulating body 112 prevents heat transfer from the engine head to the respective air pipe 103 and to other parts constituting the path of the supply air. In the insulating body 112 the charging channel 111 has an oval cross-sectional area adjoining the outlet flange 104 of the air pipe 103 and its cross-sectional area further decreases. In the embodiment shown in Fig. 4, the charging channel 111 in the insulating body 112 is bent. In an alternative embodiment, not shown, the charging channel 111 may be straight or may have only a slight bend.

The charging channel 111 has an oval cross-section in its entire length up to its branching into two circular cross-sections for the seats 107 of the intake valves 106, whereby the charging channel 111 in the head 2 , 31 , 41 , 51 is straight as far as to the point of branching. The charging channel 111 decreases in the direction away from the insulating body 111 towards the combustion chamber 113 to the smallest oval cross-section S2, from which the oval cross-section of the charging channel 111 increases until reaching the maximum cross-section S3 before the branching into two circular cross-sections for the seats 107 of the intake valves 106.

An exemplary schematic dimensional embodiment of the charging channel in the head 21 , 31 , 41 , 51 is shown in Figs. 6a a 6b. In Fig. 6a, the charging channel 111 is shown in the same section as in Fig. 4, but, for the purposes of simplicity, in a straight arrangement, whereby, for completeness sake, in the upper part of the figure is also shown the initial oval cross-section S1 in the end portion of the air pipe 103. The narrowing of the oval cross- section of the charging channel 111 from the initial oval cross-section SI into the minimum oval cross-section S2 and the subsequent increasing to the maximum oval cross-section S3 is not apparent from Fig. 6a, since it occurs in the direction perpendicular to the axis of the charging channel 111 and the cross-section plane. The dimensions of the cross-sections in this section represent the height x of the charging channel i ^anc l it ' ^s obvious from the figure that the height in the cross-section SI is XI , the height in the cross- section S2 is x2 and the height in the cross-section S3 is x3, whereby it is evident that xl in the cross-section SI is the largest and the heights x2 and _x3 are smaller, but identical, which means that in the illustrated exemplary embodiment the height of the charging channel 111 i ⁿ the head 21, 3t, 41 , 51 is constant.

In order to illustrate the changes of the cross-section, Fig. 6b shows a cross-section of the charging channel 111 along a plane which passes through the axis of the charging channel 111 and which is perpendicular to the plane of the cross-section of the charging channel 111 shown in Fig. 6a, including the initial oval cross-section SJ. in the end portion of the air pipe 103. The dimensions of the cross-sectional areas in this section represent the width y_ of the charging channel m and it is obvious from the figure that the width in the cross-section SI is y_1 , the width in the cross-section S2 is y_2 and the height in the cross-section S3 is y_3. For ease of understanding, on the right-hand side of the individual cross-sections SI , S2 and S3 are shown their exemplary shapes and sizes.

In the exemplary embodiment according to Fig. 4, a fuel injector 114 for indirect injection with a nozzle 115 is fixed in the insulating body 11, The nozzle 115 enters tangentially the bend of the charging channel 111 in the area before its smallest section S2 or, at the latest, at the point of its smallest cross-section S2. The course of reducing the cross-section of the charging channel 111 before the smallest cross-section S2 is more gradual than the increase in the cross-section of the charging channel 111 beyond the smallest cross-section S2 towards the combustion chamber, which is shown in Fig. 6b. This arrangement is a prerequisite for perfect atomization and homogenization of the fuel-air mixture. From a technological point of view, the shaped charging channel 111 may be preferably provided with an unillustrated insert fixed in the straight cylindrical portion of the charging channel 111 in the head 21, 3_1, 4J., 51 of the cylinder. To cool effectively the supply air before entering the combustion chamber 113, it is advantageous if the smallest cross-section S2 of the charging channel 111 is near the combustion chamber 113. In the area before the inlet to the combustion chamber 113 the common flow profile S3 branches into two cross-sectional areas for the seats 110 of the two intake valves 106. In the embodiment according to Fig. 4, the minimum flow profile S2 is formed in one transverse plane, i.e. at a particular point of the charging channel 111. In the embodiment according to Figs. 6a, 6b, the portion of the charging channel HI having the minimum flow profile S2 has a length L. The transitions between the individual cross-sections of the charging channel are gradual and smooth.

The nozzle 115 of the injector 114 is directed towards the discs 109 of the intake valves 106. The seats 110 of the intake valves 106 are mounted in a known manner in the head. A common feature of all the engines according to the invention, irrespective of the number of cylinders, is the fact that the decreasing inner cross-section of the entire charging conduit 6, 6001 , 6001 is followed by a sudden increase in the space of the air chamber 64, 65, 6401, 6402, 6407. The air expansion which occurs at the inlet to the air chamber 64, 65, 6401, 6402, 6407, is an important factor leading to the lowering of the supply air temperature.

The shape of the air pipe 103 and the charging channel 111 characterized by the above-mentioned changing cross-section is substantially a Venturi tube. Its principle is used here in terms of sudden expansion of the supply air, during which this air, or, more specifically, the fuel-air mixture created after its injection, is further cooled considerably. In addition, this has a positive influence on the thermal balance of the engine, whereby, at the same time, the intake valves 106 are cooled efficiently. The after-cooling of the air in the charging channel 111 takes place at the point of the narrowest cross-section S2 of the channel HI as a result of due to the pressure drop at maximum air speed, as well as in the space of the intake valves 106 due to the expandion of the mixture, during which the sprayed liquid fuel during evaporation receives the latent heat of vaporization, thereby cooling the respective portion of the charging channel 111 and, consequently, reducing the resulting temperature of the engine.

According to Fig. 7, the sealing outer surface of the circumference of the disc 109 of the intake valve 106 and the corresponding sealing surface of the seat 110 is multiangular. In an exemplary embodiment, it is formed by a conical circumferential surface 117 with a vertex angle a = 60° following the transition between the stem and the disc 109 of the valve 106 and a conical circumferential surface 118 with a vertex angle β = 120° adjoining the largest diameter of the disc 109. The specific size of the described angles may vary depending on technological conditions. This solution improves the tightness of the valve and at the same time reduces carbon deposition on the sealing surfaces of the valve 106 and the seat 110 due to the labyrinth effect of the sealing surface. The sealing surfaces of the exhaust valves, too, can be arranged similarly. The shape of the head the piston 119 is adapted to the roof-shaped combustion chamber 113. In an exemplary embodiment, the engine is made as a long-stroke engine, whereby the inner diameter of the cylinder is 86 mm and the piston stroke is 68 mm. A strong long-stroke engine is a prerequisite for achieving a sufficiently high performance for a given piston displacement volume of the cylinder without exceeding the acceptable limit of the mean piston speed, for which the speed 20 m.s ^"1 is considered as acceptable especially with respect to safe/reliable maintaining the lubricating film between the inner wall of the cylinder and the outer surface. The engine according to the invention does not exceed this limit at revolutions of 8800 min ^"1 . At top dead centre the edge of the piston 119 is situated just below peripheral planar areas 120 of the head, which are perpendicular to the axis of symmetry of the piston 119. In the respective portion of the circumference of the piston 119 face, against the areas 120 of the head are positioned corresponding areas which are parallel to the areas 120 of the head. In the roof-shaped protrusion 121 of the piston 119 are formed unillustrated recesses for the discs 109 of the valves 106, 107 or their parts, which contributes to achieving a high compression ratio, ranging from 10,4 to 11 ,1. Compression pressure is in the range between 13 and 16 bar. By compression pressure we understand the pressure in the cylinder which is achieved by compressing the air in the cylinder, the piston being in the upper position.

The drive of the camshaft 122 of the intake valves 106 and of the camshaft 123 of the exhaust valves 107 is provided with an unillustrated actuator, by which it is possible to control automatically during the operation the coupling of the camshafts 122, 123 and thereby change opening and closing times of the valves 106, 107 relative to the position of the crankshaft 102 (in principle, it is the so-called overlapping the suction and exhaust valves 106, 107). The preignition of the mixture by the spark plug 108 is at least 8°, whereby it can be increased as long as the engine efficiency, or, more precisely, the engine performance increases, usually up to approximately 30° before top dead centre. The seal 124 between the abutting area of the head 21 , 31., 41 , 51 and a corresponding abutting area of the block 10J. is realized by a high-pressure flat seal sealing both the combustion space and the unillustrated channels interconnecting the head and block cavities used for the circulation of cooling water and oil while using the maximum engine power.

The piston 119 is fitted with piston rings 125 of a substantially classical design having a rectangular cross-section of the ring, with minimum axial play between faces of the ring 125 and sides of the groove 126. In an exemplary embodiment according to Fig. 4, the space between the bottom of the groove 126 in the piston 119 and the inner diameter of the piston ring 125 is connected by means of interconnecting channels 127 to the combustion chamber 113 above the piston 119. This results in achieving the proportionality of the pressure in the combustion space and the amount of compressive force between the outer circumference of the piston ring 125 and the inner wall of the cylinder 2, 3, 4, 5, and with a plurality of interconnecting channels 127, also uniform compressive force along the circumference of the piston ring. This favourably influences the tightness of the combustion chamber, as well as the wear of the rings and the cylinder. It has been experimentally proven that the lowest number of openings is three.

In an alternative embodiment, the engine has direct fuel injection into the combustion chamber 113. The direct injection fuel injector 128 is not located in the charging pipe before the intake valve. The location of the unillustrated fuel injector 128 is apparent from Fig. 5. The nozzle of the injector 128 goes directly to the combustion chamber below the spark gap of the spark plug 108. The spark plug 108 is with its discharger turned against the fuel supply so that the fuel is directed to the open space between the electrodes unshadowed by the grounding electrode, which is shown in Figs. 4 and 5. In an internal combustion engine with indirect injection, the discharger of the spark plug 108 is turned towards the space between the pair of intake valves 106.

The above-mentioned shape and cross-section of the charging channel described in an embodiment with indirect fuel injection has not been modified, which means that the Venturi tube is preserved also in an embodiment with direct fuel injection. However, the fuel itself is not cooled as a result of the expansion and evaporation of the fuel. If the engine has direct fuel injection, the bend of the charging channel 111, which was advantageous in the engine with indirect fuel injection to the charging channel 111 in terms of the connection of the injector 114, is not necessary. In this case, the charging channel 111 and the air pipe 103 can be arranged coaxially.

In another alternative embodiment (not shown), the engine is provided with both a direct injection fuel injector 114 and an indirect injection fuel injector 128. Both injectors are used simultaneously or independently of each other, by which means it is possible to achieve further increase in the efficiency of the internal combustion engine according to the invention at the cost of a more complicated fuel system. Preferably, it is possible to use both injection modes in such a manner that at low engine revolutions only indirect injection is functioning, whereby at high revolutions only direct injection is functioning.

The internal combustion engine according to the invention may also be arranged in a radial pattern, where in terms of design analogies with the described single cylinder engine are used.

Due to the above-described construction of the path of the supply air, or the mixture of sprayed fuel and air, the internal combustion engine according to the invention is characterized by a very low operating temperature, allowing it to run at least at normal load without a cooler of the block and of the engine head. The mixing mass ratio of air and fuel during the operation of the engine according to the invention has an optimal value λ = 1 , or slightly larger. Another key feature is high performance and lower consumption at lower emissions compared to the engines of the prior art. List of references

1 crankshaft axis

100 four-cylinder engine

101 engine block

102 crankshaft

103 air pipe (between the air chamber and the head)

104 outlet flange (of the air conduit)

105 piston pin

106 intake valve

107 exhaust valve

108 spark plug

109 disc of the intake valve

110 intake valve seat

111 charging channel (between the air pipe and the inlet to the combustion chamber)

112 insulating body (between the air pipe and the head)

113 combustion chamber

114 fuel injector (for indirect injection)

115 multihole nozzle

117 conical surface of the disc and of the seat of the intake valve (with a larger vertex angle β)

118 conical surface of the disc and of the seat of the intake valve (with a smaller vertex angle a)

119 piston

120 planar surface of the edge of the inner surface of the head

121 roof-shaped protrusion of the piston

122 camshaft of the intake valves

123 camshaft of the exhaust valves

124 seal between the head and the engine block

125 piston ring

126 piston groove for the piston ring

127 connecting channel (between the piston groove and the combustion chamber)

128 fuel injector (for direct injection)

2 cylinder (of the engine)

21 cylinder head

22 exhaust pipe

3 cylinder (of the engine)

31 cylinder head (of the engine)

32 exhaust pipe

4 cylinder head

41 cylinder head

42 exhaust pipe

5 cylinder (of the engine)

51 cylinder head

52 exhaust pipe

6 charging conduit (of air)

60 connecting flange (of the intake pipe)

600 longitudinal axis of the air chamber

6001 charging conduit (of air) of single-cylinder engine 61 intake pipe (of the supply air)

610 beginning of charging conduit (6)

611 throttle valve

612 rotary axis (of the throttle valve)

62 blower

621 turbocharger

63 rectifier of the supply air

64 air chamber

6401 air chamber (of single-cylinder engine)

6402 air chamber (of four-cylinder in-line engine)

6403 inlet flange of the air chamber (of in-line engine fadoveho motoru)

6406 outlet port (of in-line engine)

6407 air chamber (of one row of eight-cylinder V-engine)

641 outlet port (of the air chamber)

6410 outlet port (of the air chamber) of single-cylinder engine

642 outlet port (of the air chamber)

65 air chamber

651 outlet port (of the air chamber)

652 outlet port (of the air chamber)

66 protrusion (of the circumference of the outlet port)

67 flange (for connecting the manifold with the elbow pipe)

,68 connecting elbow pipe (second part of the charging conduit 6 of an eight cylinder V-engine)

69 flange (for connecting the elbow pipe to the air chamber) of the head of an eight-cylinder V-engine)

;S1 oval cross-section (before the end of the air pipe)

52 minimum cross-section of the charging channel (in the area beyond the insulating body)

53 maximum cross-section of the charging channel (before the inlet to the combustion chamber)

λ air/fuel mixing ratio