DE102017116244A1 - Internal combustion engine and method for operating an internal combustion engine - Google Patents

Abstract

The invention relates to an internal combustion engine (10) for driving a motor vehicle. The internal combustion engine has an engine block (12) and a cylinder head (14) connected to the engine block (12). In the internal combustion engine, at least one combustion chamber (16) is formed, in which a piston (18) connected to a crankshaft (58) via a connecting rod (34) is displaceable and compresses a combustion air mixture. At least one fuel injector (36) with a fuel injection nozzle (20), via which fuel can be injected into the combustion chamber (16) of the internal combustion engine (10), is arranged on the cylinder head (14). In this case, the fuel injection nozzle (20) has a plurality of injection openings (22, 24) which are arranged on a first pitch circle (26) and a second pitch circle (28) of the fuel injection nozzle (20). The invention further relates to a method for operating such an internal combustion engine in which the internal combustion engine (10) is operated in a first operating state at low load with a high compression ratio (ε) and fuel into the combustion chamber (16) exclusively through the injection openings (22) on the first bolt circle (26) of the fuel injection nozzle (20). wherein the internal combustion engine (10) is operated in a second operating state at high load with a low compression ratio (ε), wherein in the combustion chamber (16) through the injection openings (22, 24) of both bolt circuits (26, 28). is injected.

Description

The invention relates to an internal combustion engine and a method for operating an internal combustion engine according to the preambles of the independent claims.

The compression ratio of modern internal combustion engines, in particular diesel engines with direct fuel injection, has a significant influence on the efficiency of the internal combustion engine and the emissions. In addition, the cold start behavior and the heating of the exhaust aftertreatment components depend significantly on the compression ratio of the internal combustion engine. Therefore, the compression ratio in constant-compression ratio internal combustion engines known from the prior art always represents a compromise of the different requirements.

In addition, internal combustion engines are known with a variable compression ratio, in which the compression ratio can be adapted to the operating condition of the internal combustion engine. From the WO 2016/016194 A1 For example, a variable compression ratio internal combustion engine is known in which, to change the compression ratio, the connecting rod length is adjusted accordingly so that the piston is spaced at top dead center according to the desired compression ratio from a combustion chamber boundary on the cylinder head. Furthermore, the WO 2016/016194 A1 a method for operating an internal combustion engine, wherein the thus adjustable compression ratio is variable at least during operation of the internal combustion engine and in addition at least one further engine component is adjusted with the change in the compression ratio.

A disadvantage of the known method, however, is that a sole adaptation of the compression ratio does not lead to an optimal operating situation of the internal combustion engine.

The object of the invention is to improve the cold start capability of an internal combustion engine and at the same time to increase the thermodynamic efficiency and to minimize emissions.

According to the invention, the object is achieved by an internal combustion engine with an engine block and a cylinder head, wherein the internal combustion engine comprises at least one combustion chamber, in which a piston for compressing a combustion air mixture is arranged. In this case, at least one fuel injection valve, preferably a fuel injector of a high-pressure injection system, is arranged in the cylinder head, which comprises a fuel injection nozzle. The internal combustion engine has a variable compression ratio, which is variable during operation of the internal combustion engine. The fuel injector has a plurality of injection ports arranged on two different pitch circles. Due to the different injection openings on several bolt circuits in conjunction with a variable compression ratio of the internal combustion engine, it is possible to meet the increasing requirements for low-emission, maximum-efficient engine operation and to overcome the disadvantages known from the prior art.

The features listed in the dependent claims advantageous improvements and developments of the internal combustion engine specified in the independent claim are possible.

In a preferred embodiment of the invention, it is provided that the injection openings of the first pitch circle have a shallower injection angle than the injection openings of the second pitch circle. The arrangement of the injection openings is preferably chosen so that the beam cone of the second circle of holes lie between the beam cones of the first circle of holes. This means that in view of the fuel injection valve from below or above, the injection openings of the second pitch circle of the bisecting line between two adjacent injection openings of the first pitch circle preferably differ by less than 20 ° and are particularly preferably arranged symmetrically on the bisector. Through a flat injection angle, the small injection quantities can be selectively introduced into a combustion bowl of the piston, so that the introduced fuel does not impinge or only in small quantities on the cold combustion chamber walls or on the piston. In this case, an efficient implementation of the fuel can be realized with low emissions.

In a further improvement of the internal combustion engine is provided that the injection openings of the first pitch circle have a smaller diameter than the injection openings of the second pitch circle. In this case, with increasing load, the injection quantity can be adjusted accordingly, so that the atomization of small amounts is just as possible as the introduction of larger amounts of fuel to achieve high performance.

In an advantageous embodiment of the invention, it is provided that the number of injection openings on the first bolt circle is greater than the number of injection openings on the second bolt circle. In this case, the first bolt circle preferably at least three, more preferably four evenly distributed over the circumference of the fuel injection nozzle injection ports, while the second bolt circle preferably has at least one injection port less than the first bolt circle, more preferably exactly two injection ports, which preferably spaced apart by 180 ° around the circumference of the fuel injection nozzle are. In this case, the flow rate of the sum of the injection holes of the second pitch circle is 50% to 400% of the flow of the sum of the injection holes of the first pitch circle, particularly preferably in the range of 70% to 200% of the flow rate of the first pitch circle. By comparatively many small injection openings on the first bolt circle, a good atomization and uniform distribution of the fuel in the combustion chamber can be realized, whereby the Rußbildneigung can be reduced.

In a preferred embodiment of the invention, it is provided that a portion of the fuel injection nozzle facing the combustion chamber of the internal combustion engine is conical, so that the first bolt circle has a diameter which is smaller than a diameter of the second bolt circle. In this case, at least one of the hole circles, preferably both hole circles, lies in the conical section of the fuel injection nozzle. Alternatively, one of the two sections may be formed in a cylindrical portion of the fuel injection nozzle. By a conical section, a relatively wide range of possible injection angles can be implemented in a comparatively simple manner, so that steeper injection angles can be implemented compared to introducing the injection openings into a cylindrical region, which is advantageous in particular for the injection openings on the second circle ,

In an advantageous improvement of the invention it is provided that the injection angle of the injection openings of the first pitch circle between 155 ° and 175 ° and the injection angle of the second pitch circle is between 90 ° and 170 °. It is particularly advantageous if the injection angle of the injection openings of the first pitch circle is at least 5 ° greater than the injection angle of the injection openings of the second pitch circle. If the injection openings of the second pitch circle have a steeper injection angle than the injection openings of the first pitch circle, the fuel metered in through the injection openings of the second pitch circle also enters the combustion recess of the piston so that the fuel can be optimally reacted.

The internal combustion engine is preferably designed as a self-igniting internal combustion engine according to the diesel principle and has no additional ignition mechanisms for the spark ignition of a combustion mixture in the combustion chambers of the internal combustion engine.

Preferably, the compression ratio of the internal combustion engine is in between 13 and 23 , wherein the compression ratio is variable continuously or in two or more concrete stages. In this case, the difference between the lowest compression ratio and the largest compression ratio is preferably 2 to 8th Units. Preferably, a difference between the lowest and the largest compression ratio of 2.5 to 6 Units, more preferably of 3 to 4 Units. Conceivable is both a continuous adjustment of the compression and a three-point or two-point adjustment, which can be technically easier to implement. With a variable compression ratio between 13 and 23 , especially between 14 and 20 , An adaptation to different operating conditions can be made, in which an improved cold start capability, accelerated heating of the exhaust aftertreatment components and a maximum efficient normal operation of the internal combustion engine is possible.

In a preferred embodiment of the invention it is therefore provided that the compression ratio in a first stage with high compression between 17 and 23 and in a second stage with low compression between 13 and 17 lies.

In a preferred embodiment of the invention it is provided that the internal combustion engine is operated in a first operating state, in particular at low load, with a high compression ratio, wherein fuel is injected into the combustion chamber exclusively through the injection openings of the first bolt circle. By a combination of high compression ratio and small injection quantity, which is metered exclusively through the injection openings of the first bolt circle, the operating behavior of the internal combustion engine can be improved, in particular in a cold start phase of the internal combustion engine.

In an advantageous embodiment it is provided that the internal combustion engine is operated in a second operating state, in particular at high load, with a low compression ratio, wherein fuel is injected both through the injection openings of the first pitch circle and through the injection openings of the second pitch circle. Through an injection through the injection openings of both hole circles and a reduced compression ratio of the internal combustion engine can achieve a higher efficiency in normal operation.

In an advantageous improvement of the internal combustion engine, it is provided that the compression ratio can be changed by changing the effective connecting rod length of a connecting rod connected to the piston. By changing the effective connecting rod length, the compression ratio of the internal combustion engine can be adjusted to achieve the aforementioned advantages

In a further improvement of the invention, it is provided that the piston has a combustion recess on its end face facing the fuel injection nozzle. Through a combustion bowl, the combustion of the fuel-air mixture in the combustion chamber can be favored, wherein an optimal mixing of the fuel injected into the combustion chamber and the air supplied through the intake valves is possible.

According to the invention, a method for operating an internal combustion engine with an engine block and a cylinder head is proposed, wherein the internal combustion engine comprises at least one combustion chamber, preferably at least three combustion chambers. In the combustion chambers connected via a connecting rod with a crankshaft piston is displaceable, via which a combustion mixture in the combustion chamber of the internal combustion engine is compressible. At least one fuel injection valve, which comprises a fuel injection nozzle, is arranged on the cylinder head. In this case, a compression ratio of the internal combustion engine, in particular by a change in the effective connecting rod length, changeable. The fuel injection nozzle has a plurality of injection openings which are arranged on a first pitch circle and a second pitch circle distributed over the circumference of the fuel injection nozzle. In this case, the internal combustion engine is in a first operating state at low load with a high compression ratio of 17 to 23 operated, in this operating state, only fuel is injected through the injection openings of the first bolt circle in the combustion chamber. Further, in a second operating state, the internal combustion engine becomes under high load with a low compression ratio of 13 to 17 operated, wherein in the at least one combustion chamber of the internal combustion engine is injected through the injection openings of both hole circles fuel. By an inventive method, the exhaust aftertreatment components can be brought to their operating temperature after a cold start faster and the cold start capability of the engine are generally improved and the efficiency of the engine can be improved in normal operation, since the compression ratio is no longer interpreted as a compromise between the different requirements, but can be adapted to the operating situation.

In an improvement of the method is provided that the internal combustion engine is operated at low temperatures in the exhaust system of the internal combustion engine, especially at temperatures below 250 ° C, more preferably at temperatures of less than 150 ° C with the high compression ratio to the cold start phase of To improve internal combustion engine and to promote the heating of the exhaust aftertreatment components, and to operate at high temperatures, especially at temperatures above 350 ° C with the low compression ratio. As a result, in a phase in which no further heating of the components of the exhaust aftertreatment in the exhaust system is necessary, the running smoothness of the internal combustion engine can be improved and the nitrogen oxide emissions can be reduced. This makes it possible, at low temperature in the exhaust duct to further improve the heating of the exhaust aftertreatment components and optionally omit the high compression ratio at high temperatures in the exhaust duct across the board, whereby the efficiency of the internal combustion engine can be increased.

The various embodiments of the invention mentioned in this application are, unless otherwise stated in the individual case, advantageously combinable with each other.

• 1 eine schematische Darstellung eines erfindungsgemäßen Verbrennungsmotors mit einem veränderbaren Verdichtungsverhältnis und eine Kraftstoffeinspritzdüse mit mehreren Lochkreisen;
• 2 eine Kraftstoffeinspritzdüse eines erfindungsgemäßen Verbrennungsmotors, bei der mehrere Einspritzöffnungen auf zwei Lochkreise verteilt sind;
• 3 eine schematische Darstellung eines ersten Betriebszustandes des Verbrennungsmotors, wobei der Verbrennungsmotor bei einer niedrigen Teillast mit einem hohen Verdichtungsverhältnis betrieben wird und die Düsennadel nur soweit öffnet, dass der Kraftstoff ausschließlich durch die Einspritzöffnungen des ersten Lochkreises in den Brennraum eingebracht wird; und
• 4 eine schematische Darstellung eines zweiten Betriebszustandes des Verbrennungsmotors, wobei der Verbrennungsmotor mit einer hohen Teillast oder Volllast mit einem niedrigen Verdichtungsverhältnis betrieben wird und die Düsennadel der Kraftstoffeinspritzdüse soweit öffnet, dass Kraftstoff sowohl durch die Einspritzöffnungen des ersten Lochkreises als auch durch die Einspritzöffnungen des zweiten Lochkreises in den Brennraum eingebracht wird.

The invention will be explained below in embodiments with reference to the accompanying drawings. Identical components or components with the same function are identified in the different figures with the same reference numerals. Show it:

• 1 a schematic representation of an internal combustion engine according to the invention with a variable compression ratio and a fuel injector with a plurality of bolt holes;
• 2 a fuel injection nozzle of an internal combustion engine according to the invention, in which a plurality of injection openings are distributed on two bolt holes;
• 3 a schematic representation of a first operating state of the internal combustion engine, wherein the internal combustion engine is operated at a low partial load with a high compression ratio and the nozzle needle opens only so far that the fuel is introduced exclusively through the injection openings of the first pitch circle in the combustion chamber; and
• 4 a schematic representation of a second operating state of the internal combustion engine, wherein the internal combustion engine with a high part load or full load with a low compression ratio is operated and the nozzle needle of the fuel injector opens so far that fuel is introduced through both the injection openings of the first pitch circle and through the injection openings of the second pitch circle in the combustion chamber.

1 shows a schematic representation of an internal combustion engine according to the invention 10 , The internal combustion engine 10 has an engine block 12 and one with the engine block 12 connected cylinder head 14 on, being in a bore of the engine block 12 a piston 18 is arranged, which via a connecting rod 34 with a crankshaft 58 connected is. The bore represents a cylinder wall 38 at which the piston 18 is guided by piston rings in a known manner. The piston 18 and the cylinder head 14 limit a combustion chamber 16 of the internal combustion engine 10 , Further, in the cylinder head 14 an inlet channel and an outlet channel for the gas exchange of the combustion chamber 16 formed, wherein the respective channels through an inlet valve 40 or an outlet valve 42 can be closed, so that the inflow or outflow into the combustion chamber 16 is temporarily prevented. To open the inlet valve 40 is an intake camshaft 54 whose cam is the inlet valve 40 in the direction of the combustion chamber 16 presses so that the inlet valve 40 is opened. To operate the exhaust valve 42 is an exhaust camshaft 56 provided, wherein a cam of the exhaust camshaft 56 the opening and closing of the exhaust valve 42 controls. Further, on the cylinder head 14 a bore for receiving a fuel injection valve 36 , in particular a fuel injector of a high-pressure injection system, in which a fuel injection valve 36 is used. The fuel injector 36 indicates at its the combustion chamber 16 facing the end of a fuel injector 20 on, at the a plurality of injection openings 22 . 24 is trained. Here are the injection openings 22 . 24 on a first bolt circle 26 and a second circle of holes 28 distributed, with the injection openings 22 on the first bolt circle 26 and the injection openings 24 on the second circle of holes 28 are arranged. In this case, the injection openings 22 of the first bolt circle 26 a first injection cone, which has a cone angle α of 155 ° to 175 ° and the injection openings 24 of the second circle of holes 28 a second injection cone, which has a cone angle β from 90 ° to 170 °, wherein the cone angle α of the first injection cone is at least 5 ° greater than the cone angle β of the second injection cone. The piston 18 indicates a fuel injector 20 facing end face 30 a combustion bowl 32 on, wherein at least the injection cone of the injection openings 22 at a piston position near top dead center into the combustion bowl 32 is directed. The compression ratio of the internal combustion engine according to the invention 10 is variable, by a known manner an effective connecting rod length I _P of the connecting rod 34 can be changed and thus the distance of the piston 18 to the cylinder head 14 can be varied at the top dead center.

2 shows a fuel injector 20 an internal combustion engine according to the invention 10 in an enlarged view. The fuel injector 20 has a nozzle body 44 and a nozzle needle 46 on, which serves as a closing member and in a valve seat 48 on the nozzle body 44 is applied. In the nozzle body 44 are a first group of injection openings, in particular of spray holes, 22 formed, which has a diameter D ₁ and on a first pitch circle 26 the fuel injector 20 are arranged. In the nozzle body 44 are also a second group of injection ports 24 formed, which on a second bolt circle 28 are arranged, and a diameter D ₂ exhibit. The first bolt circle 26 and the second bolt circle 28 are in a conical section 52 of the nozzle body 44 formed so that the first bolt circle 26 a smaller diameter D ₃ as the second circle of holes 28 which has a larger diameter D ₄ Has. Here is the cone angle β injection ports 24 of the second circle of holes 28 smaller, so that the injected fuel deeper into the combustion chamber 16 penetrates. The cone angle α of the injection openings 22 of the first bolt circle 26 is flatter, in particular near the top dead center fuel in the combustion bowl 32 of the piston 18 and not on the comparatively cold cylinder walls 38 hold true. The fuel injector 20 also has a nozzle tip 50 on which the combustion chamber 16 is facing. The number of injection ports 24 on the second circle of holes 28 is preferably 50% of the injection openings 22 on the first bolt circle 26 , Preferably, the flow rate of the second pitch circle is 50% to 400% of the first pitch circle, more preferably 70% to 200%, wherein the injection openings 24 of the second circle of holes 28 a larger diameter D ₂ as the injection ports 22 of the first bolt circle 26 exhibit. The arrangement of injection ports 24 of the second circle of holes 28 is preferably to be chosen so that the beam cone of the second bolt circle 28 between the beam cones of the first pitch circle 26 lie. This means that in view of the fuel injector 36 from below or above the injection openings 24 of the second circle of holes 28 from an angle bisector between two adjacent injection openings 22 the first circle of holes preferably deviate by less than 20 °, wherein they are particularly preferably arranged symmetrically on the bisector.

In 3 is a first operating state of an internal combustion engine according to the invention 10 with a variable compression ratio ε and a fuel injector 20 with several injection openings 22 . 24 on different hole circles 26 . 28 shown. The variable compression ratio ε be achieved by adjusting the piston position at top dead center. The bolt circles 26 . 28 have different cone angles α . β for the injection jets of the metered fuel, so that one depending on the compression ratio ε different piston position is taken into account. In the first operating state A, the internal combustion engine 10 with high compression ε ₁ at low torque T and operated according to small injection quantities, wherein the piston 18 a high piston position is set. This is the compression ratio ε ₁ at values between 17 and 23 , The goal of such a high compression ratio ε ₁ is the improvement of the stability at a late combustion center of combustion. This combination of later combustion center position and a high compression ratio ε ₁ serves the purpose of rapid heating of downstream close-coupled exhaust aftertreatment components such as a NOx storage catalyst, an oxidation catalyst, a catalyst for the selective catalytic reduction of nitrogen oxides (SCR catalyst) and / or a particulate filter to this exhaust aftertreatment as soon as possible after a cold start of the engine 10 to bring to an activation temperature. This combination also serves the purpose of obtaining the necessary temperature and heating according to exhaust aftertreatment components, so that a faster and more stable operation of these exhaust aftertreatment components is possible. In particular, this first operating state can also be used for heating the particle filter to a regeneration temperature.

The center of gravity of combustion can be at such a high compression ratio ε ₁ between 20 ° CA to 50 ° CA after top dead center of the piston 18 reach, which are not possible with lower compression ratios of known from the prior art direct injection diesel engines. For this purpose, a main injection with a center of gravity of preferably 5 ° CA to 20 ° CA after top dead center of the piston 18 meaningful. Preferably, this main injection is supplemented by a close-up pilot injection, in which the amount of injected fuel does not exceed 10% of the amount of main injection and is in the range of 1 mg to 3.5 mg of fuel. The pre-injection should not be more than 50 ° CA before the main injection. Furthermore, it is useful for internal combustion chamber post-oxidation of the resulting in late combustion center of gravity particulate matter emission to provide an early post injection, in which an injection amount that is not more than 20% of the injection quantity of the main injection into the combustion chamber 16 is metered. In this case, the injection quantity of the post-injection is in the range from 1 mg to 8 mg of fuel, which is preferably between 5 ° CA and 50 ° CA after top dead center of the piston 18 is injected. In the case of the small injection quantities in this first operating state, the injection of the fuel takes place exclusively through the injection openings 22 on the first bolt circle 26 with a wide cone angle α into the combustion chamber 32 of the piston 18 ,

In 4 is a second operating state of the internal combustion engine 10 shown in which the compression ratio ε lowered compared to the first operating state, so that a good compromise between power demand, engine load and particulate NOx trade-off is achieved. The values of the compression ratio ε ₂ for this second operating state are in the range of 13 < ε ₁ <17. The spread between the higher compression ratio ε ₁ and the lower compression ratio ε ₂ is preferably at maximum 8th Units, more preferably at 2.5 - 6 Units, ideally at 3 - 4 units. Conceivable are both a continuous adjustment of the compression ratio as well as a two-point or three-point adjustment. The following is a two-point adjustment between the higher compression ratio ε ₁ and the lower compression ratio ε ₂ but the method can also be implemented with a multi-point adjustment or a stepless adjustment.

The determination of the optimal compression ratio is preferably carried out via a speed and torque characteristic map or via an injection quantity map, wherein preferably at speeds n of less than 2500 rpm and torques or injection quantities of less than half of the maximum values, the high-compression ratio (but less favorable for efficiency) high compression ratio ε ₁ is set. To illustrate the most favorable consumption, it makes sense to correct this basic setting on other factors influencing. About the measured or modeled temperature of at least one component of the internal combustion engine 10 Downstream exhaust system, this default setting at low temperatures T ₁ , Be shifted in particular at temperatures of less than 150 ° C to higher speeds and / or injection quantities or torques. Conversely, at high temperatures T ₂ , Especially at temperatures above 350 ° C, where there is no need for further heating or keeping warm, even a smaller map area with high compression ratio ε ₁ be provided. If necessary, it is possible at high temperatures T ₂ in the exhaust duct across the board for operation with a high compression ratio ε ₁ to renounce. Further factors influencing the determination of the currently optimal compression ratio ε may be: coolant temperature, ambient or intake air temperature, boost pressure, oil temperature, charge air temperature, peak pressure in the combustion chamber 16 , as well as other measured or modeled temperatures, in particular in the exhaust passage of the internal combustion engine. Furthermore, a switching hysteresis is between the high compression ratio ε ₁ and the low compression ratio ε ₂ intended.

The adjustment of the compression ratio ε , in particular a proposed two-point adjustment, by the change of the effective Pleuellänge I _P respectively. Alternatively, an increase or decrease of the cylinder head 14 conceivable to the compression ratio ε adapt. A switching from an injection through the injection ports 22 of the first bolt circle 26 on all injection openings 22 . 24 is by a corresponding shape of nozzle needle 46 and nozzle body 44 possible, with the nozzle needle 46 can be controlled directly or indirectly.

LIST OF REFERENCE NUMBERS

10

internal combustion engine

12

block

14

cylinder head

16

combustion chamber

18

piston

20

fuel Injector

22

Injection opening (on the first bolt circle)

24

Injection opening (on the second bolt circle)

26

first bolt circle

28

second bolt circle

30

Face (of the piston)

32

combustion bowl

34

pleuel

36

Fuel injection valve

38

cylinder wall

40

intake valve

42

outlet valve

44

nozzle body

46

nozzle needle

48

valve seat

50

injector cap

52

conical section

54

intake camshaft

56

exhaust

58

crankshaft

ε

compression ratio

ε ₁

Compression ratio at high compression

ε ₂

Compression ratio at low compression

D ₁

Diameter of injection ports on the first pitch circle

D ₂

Diameter of the injection openings on the second bolt circle

D ₃

Diameter of the first bolt circle

D ₄

Diameter of the second bolt circle

I _P

Length of the connecting rod

n

rotation speed

T

torque

T ₁

first temperature in the exhaust duct

T ₂

second temperature in the exhaust duct

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• WO 2016/016194 A1 [0003]

Claims (15)

Internal combustion engine (10) with an engine block (12) and a cylinder head (14), wherein the internal combustion engine (10) at least one combustion chamber (16), in which a piston (18) for compressing a combustion air mixture is arranged, and wherein in the cylinder head (14) at least one fuel injection valve (36) is arranged, which comprises a fuel injection nozzle (20), characterized in that a compression ratio (ε) of the internal combustion engine (10) is variable and the fuel injection nozzle (20) has a plurality of injection openings (22, 24 ), which are arranged on two different hole circles (26, 28). Internal combustion engine (10) after Claim 1 , characterized in that the injection openings (22) of the first pitch circle (26) have a shallower injection angle (α) than the injection openings (24) of the second pitch circle (28). Internal combustion engine (10) after Claim 1 or 2 , characterized in that the injection openings (22) of the first pitch circle (26) have a smaller diameter (D ₁ ) than the injection openings (24) of the second pitch circle (28). Internal combustion engine (10) according to one of Claims 1 to 3 , characterized in that the number of injection openings (22) on the first pitch circle (26) is greater than the number of injection openings (24) on the second pitch circle (28). Internal combustion engine (10) according to one of Claims 1 to 4 , characterized in that the combustion chamber (16) of the internal combustion engine (10) facing tip of the fuel injector (20) is conical, so that the first bolt circle (26) has a diameter (D ₃ ) which is smaller than a diameter (D ₄ ) of the second bolt circle (28). Internal combustion engine (10) after Claim 2 , characterized in that the injection angle (α) of the injection openings (22) of the first pitch circle (26) between 155 ° and 175 ° and the injection angle (β) of the injection openings (24) of the second pitch circle (28) between 90 ° and 170 ° lies. Internal combustion engine (10) according to one of Claims 1 to 6 , characterized in that the internal combustion engine (10) is designed as a self-igniting internal combustion engine (10) according to the diesel principle. Internal combustion engine (10) according to one of Claims 1 to 7 , characterized in that the compression ratio (ε) of the internal combustion engine (10) is between 13 and 23, wherein the compression ratio (ε) is variable continuously or in two or more concrete stages. Internal combustion engine (10) after Claim 8 , characterized in that the compression ratio (ε) in a first stage with high compression between 17 ≤ ε ₁ ≤ 23 and in a second stage with low compression between 13 ≤ ε ₂ ≤ 17. Internal combustion engine (10) according to one of Claims 1 to 9 , characterized in that the internal combustion engine (10) in a first operating state with a high compression ratio (ε ₁ ) is operable, wherein only through the injection openings (22) of the first bolt circle (26) fuel is injected into the combustion chamber (16). Internal combustion engine (10) according to one of Claims 1 to 10 characterized in that the internal combustion engine (10) is operable in a second operating condition with a low compression ratio (ε ₂ ), wherein fuel passes both through the injection ports (22) of the first bolt circle (26) and through the injection ports (24) of the second Bolt circle (28) is injected. Internal combustion engine (10) according to one of Claims 1 to 11 , characterized in that the compression ratio (ε) by a change in the effective connecting rod length (I _P ) of a piston (18) connected to the connecting rod (34) is variable. Internal combustion engine (10) according to one of Claims 1 to 12 , characterized in that the piston (18) on its the fuel injection nozzle (20) facing end face (30) has a combustion bowl (32). Method for operating an internal combustion engine (10) with an engine block (12) and a cylinder head (14), wherein the internal combustion engine (10) comprises at least one combustion chamber (16), in which a piston (18) for compressing a combustion air mixture is arranged, and wherein in the cylinder head (14) at least one fuel injection valve (36) is arranged, which comprises a fuel injection nozzle (20), characterized in that a compression ratio (ε) of the internal combustion engine (10) is variable and the fuel injection nozzle (20) has a plurality of injection openings (22, 24), which are arranged on two different hole circles (26, 28), wherein the internal combustion engine (10) is operated in a first operating state at low load with a high compression ratio (ε ₁ ) and exclusively through the injection openings (22 ) on the first bolt circle (26) of the fuel injector (20) fuel in the combustion chamber (16) cc is scribed, and wherein the internal combustion engine (10) in a second operating state at high load with a low compression ratio (ε ₂ ) is operated, wherein fuel is injected into the combustion chamber (16) through the injection openings (22, 24) of both bolt circuits (26, 28). Method for operating an internal combustion engine (10) according to Claim 14 , characterized in that the internal combustion engine (10) at low temperatures (T ₁ ) in an exhaust passage of the internal combustion engine (10) with the high compression ratio (ε ₁ ) and at high temperatures (T ₂ ) in the exhaust duct with the low compression ratio (ε ₂ ) is operated.

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