EP2626531A1 - Multi-cylinder internal combustion engine and method to operate such a multi-cylinder internal combustion engine - Google Patents

Abstract

The four-cylinder in-line internal combustion reciprocating piston engine (5) has two adjacent primary cylinders (11,12) and two secondary cylinders (13,14) arranged adjacent to the primary cylinders. Each of the cylinders slidably receive respective pistons. The pistons are operatively connected with the cranks of a fourfold cranked crankshaft. The cranks are arranged in phase for the two primary cylinders. The cranks for the secondary cylinders are arranged 180 degree out of phase with respect to the primary cylinders. The secondary cylinders are selectively deactivated. An independent claim is included for an engine system with an electronic controller.

Description

• mindestens einem Zylinderkopf,
• vier entlang der Längsachse des mindestens einen Zylinderkopfes in Reihe angeordneten Zylindern, und
• einer zu einem Kurbeltrieb gehörenden Kurbelwelle, die für jeden Zylinder eine dem Zylinder zugehörige Kurbelwellenkröpfung aufweist, wobei die Kurbelwellenkröpfungen entlang der Längsachse der Kurbelwelle beabstandet zueinander angeordnet sind, bei der
• jeder Zylinder mindestens eine Auslaßöffnung zum Abführen der Abgase aus dem Zylinder via Abgasabführsystem aufweist, wozu sich an jede Auslaßöffnung eine Abgasleitung anschließt,
• die Zylinder in zwei Gruppen konfiguriert sind, wobei jeweils ein außenliegender Zylinder und der benachbarte innenliegende Zylinder eine Gruppe bilden, und
• die Abgasleitungen der Zylinder unter Ausbildung eines Abgaskrümmers stufenweise zu einer Gesamtabgasleitung zusammenführen, wobei die Abgasleitungen jeder Zylindergruppe jeweils zu einer Teilabgasleitung zusammenführen, bevor die beiden Teilabgasleitungen der zwei Zylindergruppen zu einer Gesamtabgasleitung zusammenführen.

The invention relates to an internal combustion engine with

• at least one cylinder head,
• four along the longitudinal axis of the at least one cylinder head arranged in series cylinders, and
• a belonging to a crank mechanism crankshaft having a cylinder associated crankshaft cranking for each cylinder, wherein the crankshaft cranks are spaced along the longitudinal axis of the crankshaft to each other, in the
• each cylinder has at least one outlet opening for discharging the exhaust gases out of the cylinder via exhaust gas removal system, for which purpose an exhaust gas line adjoins each outlet opening,
• the cylinders are configured in two groups, with one outer cylinder and the adjacent inner cylinder forming a group, and
• the exhaust gas lines of the cylinders merge step by step to form an exhaust gas line with the formation of an exhaust manifold, wherein the exhaust gas lines of each cylinder group merge to form a partial exhaust gas line before the two partial exhaust gas lines of the two cylinder groups combine to form an overall exhaust gas line.

Furthermore, the invention relates to a method for operating an internal combustion engine of the aforementioned type.

An internal combustion engine of the above type is used as a drive for motor vehicles. In the context of the present invention, the term internal combustion engine includes in particular gasoline engines, but also diesel engines and hybrid internal combustion engines, ie internal combustion engines, which are operated by a hybrid combustion process. Internal combustion engines have a cylinder block and a cylinder head which can be connected to one another or connected to form the individual cylinders, ie combustion chambers. The individual components will be briefly discussed below.

The cylinder block has a corresponding number of cylinder bores for receiving the pistons or the cylinder tubes. The piston of each cylinder of an internal combustion engine is axially movably guided in a cylinder tube and limits together with the cylinder tube and the cylinder head the combustion chamber of a cylinder. The piston head forms a part of the combustion chamber inner wall and seals together with the piston rings the combustion chamber against the cylinder block or the crankcase, so that no combustion gases or combustion air get into the crankcase and no oil gets into the combustion chamber.

The piston serves to transfer the gas forces generated by the combustion to the crankshaft. For this purpose, the piston is articulated by means of a piston pin with a connecting rod, which in turn is movably mounted in the region of a Kurbelwellenkröpfung on the crankshaft.

The crankshaft mounted in the crankcase receives the connecting rod forces, which are composed of the gas forces due to the fuel combustion in the combustion chamber and the mass forces due to the non-uniform movement of the engine parts. In this case, the oscillating stroke movement of the piston is transformed into a rotating rotational movement of the crankshaft. The crankshaft transmits the torque to the drive train.

Modern internal combustion engines are operated almost exclusively by a four-stroke work process. As part of the charge change, the expulsion of the combustion gases via the outlet openings of the at least four cylinders and the filling of the combustion chambers with fresh mixture or charge air via the inlet openings takes place. In order to control the charge cycle, an internal combustion engine requires control means and actuators to operate these controls. To control the charge cycle four-stroke engines almost exclusively lift valves are used as control members that perform an oscillating lifting movement during operation of the internal combustion engine and thus release the inlet and outlet ports and close. The valve actuation mechanism required to move the valves including the valves themselves is referred to as a valve train. The at least one cylinder head is generally used to accommodate this valve train.

It is the task of the valve train to open the intake and exhaust ports of the cylinder in time or close, with a quick release of the largest possible flow cross sections is sought to keep the throttle losses in the incoming and outflowing gas flows low and the best possible filling of Combustion rooms with fresh mixture or an effective, d. H. To ensure complete removal of the exhaust gases. Therefore, the cylinders are also often provided with a plurality of inlet and outlet ports.

The intake ports leading to the intake ports and the exhaust ports, d. H. the exhaust pipes, which adjoin the outlet openings are at least partially integrated in the cylinder head according to the prior art. The exhaust gas lines of the cylinders are usually combined to form a common overall exhaust gas line. The combination of exhaust pipes to an overall exhaust line is generally and in the context of the present invention referred to as exhaust manifold, wherein the exhaust manifold may be considered as belonging to the Abgasabführsystem.

In the internal combustion engine according to the invention, the exhaust gas lines of four cylinders are combined to form an exhaust manifold to a single overall exhaust line. In this case, the exhaust pipes of the cylinder are gradually brought together in such a way that each merge the at least one exhaust pipe of an outer cylinder and the at least one exhaust pipe of the adjacent inner cylinder to a partial exhaust gas line and the two partial exhaust gas lines formed in this way the four cylinders or two Combine cylinder groups to form an overall exhaust gas line. With this measure, the total travel distance of all exhaust pipes and thus the volume of the manifold can be significantly reduced. The trained exhaust manifold may be partially or completely integrated in the at least one cylinder head.

The dynamic wave processes or pressure fluctuations in the exhaust gas removal system are the reason why the thermodynamically displaced working cylinders of a multi-cylinder internal combustion engine influence each other during the charge cycle, especially hamper. A deteriorated torque characteristic or a reduced power supply may be the result. If the exhaust gas lines of the individual cylinders are guided separately from one another for a longer distance, the mutual influence of the cylinders during the charge exchange can be counteracted.

The evacuation of the combustion gases from a cylinder of the internal combustion engine in the context of the charge exchange is based essentially on two different mechanisms. At the beginning of the charge cycle, when the exhaust valve opens near bottom dead center, the combustion gases flow at high speed through the exhaust port into the exhaust system due to the high pressure level prevailing in the cylinder at the end of combustion and the associated high pressure difference between the combustion chamber and the exhaust tract. This pressure-driven flow process is accompanied by a high pressure peak, which is also referred to as Vorlaßstoß and propagates along the exhaust pipe at the speed of sound, the pressure decreases with increasing distance and depending on the routing due to friction more or less, d. H. reduced.

In the course of the charge cycle, the pressures in the cylinder and in the exhaust pipe are largely the same, so that the combustion gases are significantly pushed out as a result of the stroke of the piston.

Depending on the specific configuration of the Abgasabführsystems run the pressure waves that emanate from a cylinder, not only through the at least one exhaust pipe of this cylinder, but also the exhaust pipes of the other cylinder along and possibly up to the provided at the end of the respective line and open outlet opening.

Exhaust gas which has already been ejected into or discharged from an exhaust pipe during the charge cycle can therefore again enter the cylinder, due in part to the pressure wave which emanates from another cylinder.

For example, in a four-cylinder in-line engine whose cylinders are operated with the ignition sequence 1 - 3 - 4 - 2, short exhaust pipes can also cause the fourth cylinder to fire the third cylinder preceding the ignition sequence, ie the previously ignited one Cylinder, during the charge change adversely affected and derived from the fourth cylinder exhaust gas enters the third cylinder before close the exhaust valves.

The problem described above concerning the mutual influence of the cylinders during the charge cycle is of increasing relevance in the structural design of internal combustion engines, since a development toward short exhaust gas conduits can be observed in the design of the exhaust manifold.

Thus, it is advantageous for several reasons, the exhaust pipes of the cylinder starting from the respective outlet opening to the collection point in the exhaust manifold, at which merge the exhaust pipes to a common exhaust manifold and the hot exhaust gas of the cylinder is collected, as short as possible, for example, the exhaust manifold as far as possible to integrate into the at least one cylinder head and make the merger of the exhaust pipes to a total exhaust line as far as possible already in the cylinder head.

On the one hand, this leads to a more compact design of the internal combustion engine and a denser packaging of the entire drive unit in the engine compartment. On the other hand, there are cost advantages in the production and assembly as well as a reduction in weight, in particular in a complete integration of the exhaust manifold in the cylinder head

Furthermore, short exhaust pipes may advantageously affect the location and operation of an exhaust aftertreatment system provided downstream of the cylinders. The path of the hot exhaust gases to the exhaust aftertreatment systems should be as short as possible so that the exhaust gases are given little time to cool down and the exhaust aftertreatment systems reach their operating temperature or light-off temperature as quickly as possible, in particular after a cold start of the internal combustion engine.

In this context, efforts are made to minimize the thermal inertia of the section of the exhaust pipes between the exhaust port on the cylinder and the exhaust aftertreatment system, which can be achieved by reducing the mass and the length of this section, ie by shortening the corresponding exhaust pipes.

In supercharged by exhaust gas turbocharged internal combustion engines, it is desirable to keep the turbine as close as possible to the outlet, d. H. the exhaust ports of the cylinder, to order, in this way the exhaust enthalpy of the hot exhaust gases, which is largely determined by the exhaust gas pressure and the exhaust gas temperature to use optimally and to ensure a fast response of the turbocharger. Again, the thermal inertia and the volume of the conduit system between the outlet openings of the cylinder and the turbine should be minimized, which in turn the shortening of the lines of this line system is expedient, for example by at least partially integration of the exhaust manifold in the cylinder head.

Increasingly often, the exhaust manifold is integrated into the cylinder head in order to participate in a provided for in the cylinder head cooling and the manifold does not have to produce from thermally highly resilient materials that are costly.

The shortening of the exhaust pipes of the exhaust manifold, for example, by integration in the cylinder head, has - as stated above - a variety of advantages, but in addition to the shortening of the total travel distance of all exhaust pipes also leads to a shortening of the individual exhaust pipes, as these already merged immediately downstream of the exhaust ports be, which aggravates the problem of mutual influence of the cylinder when changing the charge.

Against the background of the above, it is an object of the present invention to provide an internal combustion engine according to the preamble of claim 1, d. H. of the generic type to provide, on the one hand, the requirement for a compact exhaust manifold with short exhaust pipes takes into account and with the other hand, the problem of mutual influence of the cylinder when changing the charge repair or mitigate.

A further sub-task of the present invention is to show a method for operating such an internal combustion engine.

• mindestens einem Zylinderkopf,
• vier entlang der Längsachse des mindestens einen Zylinderkopfes in Reihe angeordneten Zylindern, und
• einer zu einem Kurbeltrieb gehörenden Kurbelwelle, die für jeden Zylinder eine dem Zylinder zugehörige Kurbelwellenkröpfung aufweist, wobei die Kurbelwellenkröpfungen entlang der Längsachse der Kurbelwelle beabstandet zueinander angeordnet sind, bei der
• jeder Zylinder mindestens eine Auslaßöffnung zum Abführen der Abgase aus dem Zylinder via Abgasabführsystem aufweist, wozu sich an jede Auslaßöffnung eine Abgasleitung anschließt,
• die Zylinder in zwei Gruppen konfiguriert sind, wobei jeweils ein außenliegender Zylinder und der benachbarte innenliegende Zylinder eine Gruppe bilden, und
• die Abgasleitungen der Zylinder unter Ausbildung eines Abgaskrümmers stufenweise zu einer Gesamtabgasleitung zusammenführen, wobei die Abgasleitungen jeder Zylindergruppe jeweils zu einer Teilabgasleitung zusammenführen, bevor die beiden Teilabgasleitungen der zwei Zylindergruppen zu einer Gesamtabgasleitung zusammenführen,
  und die dadurch gekennzeichnet ist, dass
• die beiden Kurbelwellenkröpfungen der zwei Zylinder jeder Zylindergruppe in Umfangsrichtung um die Längsachse der Kurbelwelle herum keinen Versatz aufweisen, so dass die Zylinder einer Zylindergruppe mechanisch gleichlaufende Zylinder sind, und die Kurbelwellenkröpfungen der einen Zylindergruppe gegenüber den Kurbelwellenkröpfungen der anderen Zylindergruppe in Umfangsrichtung um 180° versetzt auf der Kurbelwelle angeordnet sind.

The first subtask is solved by an internal combustion engine

• at least one cylinder head,
• four along the longitudinal axis of the at least one cylinder head arranged in series cylinders, and
• a belonging to a crank mechanism crankshaft having a cylinder associated crankshaft cranking for each cylinder, wherein the crankshaft cranks are spaced along the longitudinal axis of the crankshaft to each other, in the
• each cylinder has at least one outlet opening for discharging the exhaust gases out of the cylinder via exhaust gas removal system, for which purpose an exhaust gas line adjoins each outlet opening,
• the cylinders are configured in two groups, with one outer cylinder and the adjacent inner cylinder forming a group, and
• the exhaust gas lines of the cylinders gradually merge to form an exhaust gas line with the formation of an exhaust manifold, wherein the exhaust gas lines merge each cylinder group to a partial exhaust gas line before the two partial exhaust gas lines of the two cylinder groups combine to form an overall exhaust gas line,
  and which is characterized in that
• the two crankshaft cranks of the two cylinders of each cylinder group have no offset circumferentially about the longitudinal axis of the crankshaft so that the cylinders of one cylinder group are mechanically co-rotating cylinders and the crankshaft cranks of one cylinder group are circumferentially offset by 180 ° from the crankshaft cranks of the other cylinder group the crankshaft are arranged.

The exhaust pipes of the four cylinders of the at least one cylinder head of the internal combustion engine are in a first stage in groups, ie in pairs, merged, each an outboard cylinder and the adjacent inner cylinder form a pair of cylinders whose exhaust pipes merge to form a partial exhaust gas line. In a second stage, these partial exhaust gas lines are then combined downstream in the exhaust gas discharge system to form an overall exhaust gas line. The total travel distance of all exhaust pipes is thereby shortened. The Gradual merging of the exhaust pipes to an overall exhaust line also contributes to a more compact, ie less bulky construction.

The exhaust gas flows of the two cylinder groups according to the invention kept separated longer than the exhaust gas flows within a group. The formation of the partial exhaust gas lines and their wegstreckenmäßig longer separation from each other have the effect that one cylinder group does not influence the other cylinder group when changing the charge or less.

Due to the structural design of the exhaust manifold, in particular the formation of partial exhaust gas lines, there is in principle the possibility that the cylinders of a group interfere with each other during the charge cycle.

However, this problem is mitigated in the present case by the choice of a suitable ignition sequence. The four cylinders are operated in such a way that the cylinders of a cylinder group have the largest possible offset in terms of work processes, d. H. It is alternately in a cylinder of a cylinder group and a cylinder of the other cylinder group, the combustion - for example by means of spark ignition - initiated. In this case, process variants may be advantageous in which the cylinders are ignited in the order 1 - 3 - 2 - 4 or in the order 1 - 4 - 2 - 3. The numbering of the cylinders of an internal combustion engine is regulated in DIN 73021. For in-line engines, the cylinders are counted in sequence.

The cylinders are ignited at a distance of 180 ° CA, so that starting from the first cylinder the ignition times measured in ° CA are the following: 0-180-360-540. Consequently, the cylinders of one cylinder group have a thermodynamic offset of 360 ° CA. Taking into account that the exhaust valves usually have an opening duration between 220 ° CA and 260 ° CA, it becomes clear that the cylinders of a group can not influence the change of charge in the selected firing order, regardless of how quickly the cylinders Merging the exhaust pipes downstream of the outlet openings to a partial exhaust gas line takes place.

A firing order deviating from the conventional firing sequence 1 - 3 - 4 - 2 also requires a crankshaft which deviates from the conventional crankshaft, that is to say a crankshaft which deviates from the conventional firing sequence 1 - 3 - 4 - 2. H. a deviating from the conventional Kurbelwellenkröpfung crankshaft cranking.

According to the invention, a crankshaft is used, with which the cylinders of a cylinder group run mechanically, d. H. go through the top and bottom dead center at the same time. The associated crankshaft cranks of the two cylinders may for this purpose have no offset in the circumferential direction about the longitudinal axis of the crankshaft. The thermodynamic offset of 360 ° KW is then realized by the firing order.

In order to realize a firing interval of 180 ° CA with respect to the entirety of the four cylinders, the crankshaft cranks of one cylinder group are rotated in the circumferential direction by 180 ° with respect to the crankshaft cranks of the other cylinder group. H. added.

The internal combustion engine according to the invention is an internal combustion engine which has a compact exhaust manifold with short exhaust pipes and at the same time eliminates the problem of mutual influence of the cylinder during the charge cycle, which is why the internal combustion engine according to the invention solves the first sub-task on which the invention is based.

An internal combustion engine according to the invention may also have two cylinder heads, if, for example, eight cylinders are arranged distributed on two cylinder banks. The merging of the exhaust pipes in the then two cylinder heads according to the invention can then also be used to improve the charge cycle and to improve the torque supply.

Further advantageous embodiments of the internal combustion engine are discussed in connection with the subclaims.

As already described, it is advantageous to integrate the exhaust manifold as far as possible in the at least one cylinder head, ie make the merger of the exhaust pipes as far as possible already in the cylinder head, as this leads to a more compact design, dense packaging allows and cost advantages and Show weight advantages. In addition, there may be advantages in terms of the response of a provided in Abgasabführsystem exhaust gas turbocharger or an exhaust aftertreatment system and with respect to the material to be used for the manifold.

For the reasons mentioned above, embodiments of the internal combustion engine are particularly advantageous in which the exhaust gas lines of the cylinder groups merge to form partial exhaust gas lines within the at least one cylinder head, forming two integrated partial exhaust gas manifolds.

Ie. the merging of the exhaust gas lines of each of the two cylinder groups to a partial exhaust gas line belonging to this cylinder group takes place according to the embodiment in question within the cylinder head.

Embodiments of the internal combustion engine in which the exhaust lines of the cylinders merge within the at least one cylinder head to form an overall exhaust gas line, forming an integrated exhaust manifold within the at least one cylinder head, are advantageous.

According to the above embodiment, the partial exhaust gas lines formed in the cylinder head already converge within the cylinder head to form an overall exhaust gas line. In this respect, the entire, guided by the Abgasabführsystem exhaust gas leaves the cylinder head through a single outlet opening on the outlet side outside of the cylinder head.

The present embodiment is characterized by a very compact design that has all the advantages of having an exhaust manifold fully integrated with the cylinder head.

Nonetheless, embodiments of the internal combustion engine may also be advantageous in which the partial exhaust gas lines of the cylinders outside the at least one cylinder head merge to form an overall exhaust gas line. The exhaust gas lines of the cylinders of a group lead thereby preferably together within the cylinder head to a partial exhaust gas line. The exhaust manifold is then modular and consists of a in the Cylinder head integrated manifold section, namely two Abgasteilkrümmern, and an external manifold or manifold section together.

The exhaust gas streams of the partial exhaust gas lines are kept separate from one another at least until they leave the cylinder head, so that the exhaust gas exhaust system emerges from the cylinder head in the form of two outlet openings. The partial exhaust gas lines are combined downstream of the cylinder head and thus only outside of the cylinder head to form an overall exhaust gas line. This may be upstream or downstream of exhaust after-treatment or exhaust turbocharging.

Embodiments of the internal combustion engine in which the internal combustion engine is a naturally aspirated engine are advantageous.

However, embodiments of the internal combustion engine in which a charging device is provided are particularly advantageous. The exhaust gases in the cylinders of a supercharged internal combustion engine have significantly higher pressures during operation of the internal combustion engines, which is why the dynamic wave processes in the exhaust system during the gas exchange are significantly more pronounced, in particular the pre-exhaust.

Accordingly, the problem of the mutual influence of the cylinder when changing the charge in supercharged internal combustion engines has an even higher relevance.

Particularly advantageous embodiments of the internal combustion engine, in which at least one exhaust gas turbocharger is provided which comprises a turbine arranged in the Abgasabführsystem.

The advantages of an exhaust gas turbocharger, for example compared to a mechanical supercharger, are that there is no mechanical connection to the power transmission between the supercharger and the internal combustion engine. While a mechanical supercharger obtains the energy required for its drive completely from the internal combustion engine, the exhaust gas turbocharger uses the exhaust gas energy of the hot exhaust gases. The output of the exhaust gas flow to the turbine energy is used to drive a compressor, which promotes the charge air supplied to it and compressed, creating a Charging the cylinder is achieved. Optionally, a charge air cooling is provided, with which the compressed combustion air is cooled before entering the cylinder.

The charge is used primarily to increase the performance of the internal combustion engine. However, charging is also a suitable means of shifting the load spectrum to higher loads under the same vehicle boundary conditions, as a result of which specific fuel consumption can be reduced.

In this connection, embodiments of the internal combustion engine in which the turbine of the at least one exhaust gas turbocharger is arranged in the overall exhaust gas line are advantageous.

In internal combustion engines in which the partial exhaust gas lines of the cylinder merge outside the at least one cylinder head to form an overall exhaust line, embodiments of the internal combustion engine may also be advantageous, which are characterized in that the turbine of the at least one exhaust gas turbocharger is a double-flow turbine having an inlet region with two inlet channels in each case one of the two partial exhaust gas lines opens into one of the two inlet channels.

This embodiment is also advantageous because the partition wall between the inlet ducts of the twin-flow turbine runs vertically and the two partial exhaust gas ducts perpendicular thereto - offset from one another along the longitudinal axis of the cylinder head - emerge from the head. In this respect, the arrangement of the partition wall or the inlet channels corresponds to the outlet structure of the two partial exhaust gas lines.

Nonetheless, the turbine can be designed as a twin-flow turbine even if it is placed in the overall exhaust line.

Embodiments of the internal combustion engine in which two exhaust-gas turbochargers are provided which comprise two turbines arranged in the exhaust-gas removal system are particularly advantageous.

If only one exhaust gas turbocharger is provided, a torque drop is frequently observed when falling below a certain engine speed. This is understandable Torque drop when taking into account that the boost pressure ratio depends on the turbine pressure ratio. If, for example, the speed is reduced, this leads to a smaller exhaust gas mass flow and thus to a smaller turbine pressure ratio. As a result, at lower speeds, the boost pressure ratio also decreases, which is equivalent to a torque drop.

In principle, it is possible to counteract the drop in boost pressure by reducing the size of the turbine cross section and the associated increase in the turbine pressure ratio, but this leads to disadvantages at high rotational speeds.

The torque characteristic of a supercharged internal combustion engine is therefore often tried to improve by using more than one exhaust gas turbocharger, d. H. by a plurality of turbochargers arranged in parallel or in series, d. H. by a plurality of turbines arranged in parallel or in series.

If two exhaust gas turbochargers are provided, embodiments of the internal combustion engine are advantageous in which the two turbines are arranged in series in the overall exhaust gas line.

By switching in series of two exhaust gas turbochargers, one of which is an exhaust gas turbocharger as a high pressure stage and an exhaust gas turbocharger as a low pressure stage, the compressor map can be widened in an advantageous manner both towards smaller compressor streams and towards larger compressor streams.

In particular, in the case of the exhaust gas turbocharger serving as a high-pressure stage, it is possible to shift the surge limit to smaller compressor flows, whereby high charge pressure ratios can be achieved even with small compressor flows, which significantly improves the torque characteristic in the lower part load range. This is achieved by designing the high-pressure turbine for small exhaust gas mass flows and providing a bypass line, with which increasing exhaust gas mass flow increasingly exhaust gas is passed to the high-pressure turbine. For this purpose, the bypass line branches off the exhaust system upstream of the high-pressure turbine and re-enters the exhaust gas system downstream of the turbine, wherein a shut-off element is arranged in the bypass line in order to control the exhaust gas flow passed by the high-pressure turbine.

The response of such a supercharged internal combustion engine - especially in the partial load range - is significantly improved over a comparable internal combustion engine with single-stage charging. The reason for this is also to be seen in the fact that the smaller high-pressure stage is less sluggish than a larger exhaust gas turbocharger used in the context of a single-stage supercharger, because the rotor of a smaller exhaust gas turbocharger can accelerate and decelerate faster.

In internal combustion engines in which the partial exhaust gas lines of the cylinders merge outside the at least one cylinder head to form an overall exhaust gas line, embodiments may also be advantageous, which are characterized in that a turbine is arranged in each of the two partial exhaust gas lines.

Also by two parallel turbines, the torque characteristics of a supercharged internal combustion engine can be significantly improved. In the present case it is possible, both small turbines close to the engine, d. H. immediately adjacent to the cylinder head, to arrange.

The turbine of the at least one exhaust gas turbocharger can be equipped with a variable turbine geometry, which allows a further adaptation to the respective operating point of the internal combustion engine by adjusting the turbine geometry or the effective turbine cross section. In this case, adjustable guide vanes for influencing the flow direction are arranged in the inlet region of the turbine. Unlike the vanes of the rotating impeller, the vanes do not rotate with the shaft of the turbine.

If the turbine has a fixed invariable geometry, the vanes are not only stationary, but also completely immovable in the entry area, i. H. rigidly fixed. With a variable geometry, however, the guide vanes are indeed arranged stationary, but not completely immobile, but rotatable about its axis, so that the flow of the blades can be influenced.

Embodiments of the internal combustion engine in which the at least one cylinder head is equipped with an integrated coolant jacket are advantageous. Especially supercharged internal combustion engines are highly loaded thermally, which is why high demands are placed on the cooling.

In principle, it is possible to carry out the cooling in the form of air cooling or liquid cooling. With a liquid cooling but much larger amounts of heat can be dissipated than is possible with an air cooling.

The liquid cooling requires the equipment of the internal combustion engine, d. H. the cylinder head or the cylinder block, with an integrated coolant jacket, d. H. the arrangement of the coolant through the cylinder head or cylinder block leading coolant channels. The heat is already released inside the component to the coolant. The coolant is conveyed by means of a pump arranged in the cooling circuit, so that it circulates in the coolant jacket. The heat given off to the coolant is removed in this way from the interior of the head or block and removed from the coolant in a heat exchanger again.

Advantageous embodiments of the internal combustion engine, in which each cylinder has at least two outlet openings for discharging the exhaust gases from the cylinder.

As already stated, a rapid release of the largest possible flow cross sections is sought during the charge cycle, in order to keep the throttle losses in the outflowing exhaust gas flows low and to ensure an effective discharge of the exhaust gases. Therefore, it is advantageous to equip the cylinder with two or more outlet openings.

Internal combustion engines are equipped with various exhaust aftertreatment systems to reduce pollutant emissions. For oxidation of the unburned hydrocarbons and carbon monoxide, an oxidation catalyst may be provided in the exhaust system. In gasoline engines, catalytic reactors are used, in particular three-way catalysts with which nitrogen oxides are reduced by means of the unoxidized exhaust gas components, namely the carbon monoxides and the unburned hydrocarbons, wherein at the same time these exhaust gas components are oxidized. In internal combustion engines, which are operated with an excess of air, so for example in lean-burn gasoline engines, but in particular Direct injection diesel engines but also direct injection gasoline engines, the nitrogen oxides contained in the exhaust gas can not be reduced due to the principle lack of reducing agents. To reduce the nitrogen oxides, selective catalysts - so-called SCR catalysts - are used, in which targeted reducing agents are introduced into the exhaust gas to selectively reduce the nitrogen oxides. In principle, the nitrogen oxide emissions can also be reduced with so-called nitrogen oxide storage catalysts, also called LNTs. In this case, the nitrogen oxides are first absorbed during lean operation of the internal combustion engine in the catalytic converter, ie collected and stored, in order then to be reduced during a regeneration phase, for example by means of a substoichiometric operation (λ <1) of the internal combustion engine in the event of an oxygen deficiency. To minimize the emission of soot particles, so-called regenerative particle filters are used, which filter out and store the soot particles from the exhaust gas. The particles are intermittently burned as part of the regeneration of the filter.

In the case of the internal combustion engine according to the invention, embodiments are also advantageous in which at least one exhaust aftertreatment system is provided in the exhaust gas removal system.

Corresponding to the different embodiments of the exhaust manifold or the Abgasabführsystems arise various ways of exhaust aftertreatment.

Embodiments of the internal combustion engine in which the at least one exhaust aftertreatment system is arranged in the overall exhaust gas line can be advantageous. The entire exhaust gas shares a common aftertreatment system.

In internal combustion engines in which the partial exhaust gas lines of the cylinders merge outside the at least one cylinder head to form an overall exhaust gas line, embodiments of the internal combustion engine may also be advantageous, which are characterized in that an exhaust gas aftertreatment system is arranged in each of the two partial exhaust gas lines. In the overall exhaust gas line, to which the two partial exhaust gas lines lead together downstream, a further exhaust gas aftertreatment system can also be provided, optionally also another type of exhaust aftertreatment system.

The second sub-task on which the invention is based, namely to disclose a method for operating an internal combustion engine according to a previously described type, is achieved by a method according to which the combustion in the cylinders is initiated at a distance of 180 ° CA.

The initiation, d. H. Initiation of the combustion can be carried out both by a spark ignition, for example by means of a spark plug, as well as by auto-ignition or compression ignition. In this respect, the method can be used in gasoline engines, but also in diesel engines and hybrid internal combustion engines.

The comments made in connection with the internal combustion engine according to the invention also apply to the inventive method.

In internal combustion engines whose cylinders are equipped to initiate a spark ignition with igniters, process variants can be advantageous, which are characterized in that the cylinders are ignited by means of igniters in the order 1-3-3-4 and at a distance of 180 ° KW. Beginning with an outer cylinder, the cylinders are numbered consecutively along the longitudinal axis of the at least one cylinder head and numbered.

However, process variants may also be advantageous in which the cylinders are ignited by means of ignition devices in the order 1 - 4 - 2 - 3 and at a distance of 180 ° KW. Beginning with an outer cylinder, the cylinders are numbered consecutively along the longitudinal axis of the at least one cylinder head and numbered.

According to the two preceding method variants, the two cylinders of a cylinder group have the greatest possible offset with regard to their work processes, namely a thermodynamic offset of 360 ° KW. It is initiated alternately in a cylinder of a cylinder group and a cylinder of the other cylinder group, the combustion by means of spark ignition.

Fig. 1

schematisch den im Zylinderkopf integrierten Abschnitt des Abgaskrümmers einer ersten Ausführungsform der Brennkraftmaschine in der Draufsicht,

Fig. 2

schematisch den im Zylinderkopf integrierten Abschnitt des Abgaskrümmers einer zweiten Ausführungsform der Brennkraftmaschine in der Draufsicht, und

Fig. 3

eine Ausführungsform der Kurbelwelle der Brennkraftmaschine als Prinzipskizze.

In the following the invention is based on two embodiments according to the FIGS. 1 to 3 described in more detail. Hereby shows:

Fig. 1

2 is a schematic plan view of the cylinder head integrated portion of the exhaust manifold of a first embodiment of the internal combustion engine;

Fig. 2

schematically the integrated into the cylinder head portion of the exhaust manifold of a second embodiment of the internal combustion engine in plan view, and

Fig. 3

an embodiment of the crankshaft of the internal combustion engine as a schematic diagram.

FIG. 1 schematically shows the cylinder head integrated portion of the exhaust manifold 7 of a first embodiment of the internal combustion engine in plan view.

The associated cylinder head (not shown) has four cylinders 1, 2, 3, 4 which are arranged in series along the longitudinal axis of the cylinder head. The cylinder head thus has two outer cylinders 1, 4 and two inner cylinders 2, 3.

Each cylinder 1, 2, 3, 4 has two outlet openings 5, followed by the exhaust pipes 8 of the Abgasabführsystems 6 for discharging the exhaust gases. The exhaust pipes 8 of the cylinders 1, 2, 3, 4 lead gradually to an overall exhaust line 10, wherein in each case the two exhaust pipes 8 of an outer cylinder 1, 4 and the two exhaust pipes 8 of the adjacent inner cylinder 2, 3 to one of this cylinder group associated partial exhaust gas line 9 merge before the two partial exhaust gas lines 9 of the four cylinders 1, 2, 3, 4 merge to form an overall exhaust gas line 10.

At the in FIG. 1 illustrated exhaust manifold 7 is a fully integrated in the cylinder head exhaust manifold 7, ie, the exhaust pipes 8 of the cylinders 1, 2, 3, 4 lead together within the cylinder head to form the exhaust manifold 7 to an overall exhaust line 10.

FIG. 2 schematically shows the cylinder head integrated portion of the exhaust manifold 7 of a second embodiment of the internal combustion engine in plan view. It should only the differences to the in FIG. 1 illustrated embodiment, why in the The rest is referred to FIG. 1 , The same reference numerals have been used for the same components.

The exhaust pipes 8 of the two cylinder groups lead together to form partial exhaust gas lines 9, forming two integrated partial exhaust manifolds 7a, 7b within the cylinder head. Unlike the embodiment according to FIG. 1 However, these partial exhaust gas lines 9 only together outside the cylinder head to an overall exhaust gas line (not shown), so that the partial exhaust gas lines 9 are separated from each other over a longer distance.

FIG. 3 shows an embodiment of the crankshaft 15 of the internal combustion engine as a schematic diagram.

The illustrated crankshaft 15 has five bearings 16 and has for each cylinder a crankshaft cranking 11, 12, 13, 14 associated with the cylinder. The crankshaft crests 11, 12, 13, 14 are spaced apart along the longitudinal axis 15a of the crankshaft 15, the two crankshaft crests 11, 12, 13, 14 of the two cylinders of each cylinder group having no offset in the circumferential direction about the longitudinal axis 15a of the crankshaft 15 such that the cylinders of each cylinder group are mechanically co-rotating cylinders. The crankshaft cranks 11, 12 of the first two cylinders, d. H. the first cylinder group, are compared with the crankshaft crankings 13, 14 of the third and fourth cylinder, d. H. the second cylinder group, offset in the circumferential direction by 180 ° on the crankshaft 15.

The forces acting on the crankshaft cranks 11, 12, 13, 14 mass forces F are identified. The mass moment M resulting from the inertial forces is preferably compensated by means of mass compensation.

reference numeral

1

first cylinder, outboard cylinder

2

second cylinder, internal cylinder

3

third cylinder, internal cylinder

4

fourth cylinder, outboard cylinder

5

outlet

6

Abgasabführsystem

7

exhaust manifold

7a

Abgasteilkrümmer

7b

Abgasteilkrümmer

8th

exhaust pipe

9

Part exhaust pipe

10

Total exhaust pipe

11

Crankshaft throw of the first cylinder

12

Crankshaft throw of the second cylinder

13

Crankshaft throw of the third cylinder

14

Kurbelwellenkröpfung the fourth cylinder

15

crankshaft

15a

Longitudinal axis of the crankshaft

16

Crankshaft bearings, bearings

F

mass force

° CA

Degree crank angle

M

mass moment

Claims (17)

Internal combustion engine with at least one cylinder head, - Four arranged along the longitudinal axis of the at least one cylinder head in series cylinders (1, 2, 3, 4), and - One belonging to a crank mechanism crankshaft (15), for each cylinder (1, 2, 3, 4) has a the cylinder (1, 2, 3, 4) associated crankshaft crank (11, 12, 13, 14), wherein the crankshaft cranks (11, 12, 13, 14) are spaced apart along the longitudinal axis (15a) of the crankshaft (15), in which - Each cylinder (1, 2, 3, 4) at least one outlet opening (5) for discharging the exhaust gases from the cylinder (1, 2, 3, 4) via Abgasabführsystem (6), including at each outlet opening (5) a Exhaust pipe (8) connects, - The cylinders (1, 2, 3, 4) are configured in two groups, wherein each of an outer cylinder (1, 4) and the adjacent inner cylinder (2, 3) form a group, and - The exhaust pipes (8) of the cylinder (1, 2, 3, 4) merge stepwise to form an exhaust manifold (7) to an overall exhaust line (10), wherein the exhaust pipes (8) merge each cylinder group to a partial exhaust gas line (9), before the two partial exhaust gas lines (9) of the two cylinder groups combine to form an overall exhaust gas line (10),
characterized in that - The two crankshaft cranks (11, 12, 13, 14) of the two cylinders (1, 2, 3, 4) of each cylinder group in the circumferential direction around the longitudinal axis (15a) of the crankshaft (15) around have no offset, so that the cylinder ( 1, 2, 3, 4) of a cylinder group are mechanically concurrent cylinders (1, 2, 3, 4), and the crankshaft cranks (11, 12, 13, 14) of the one cylinder group with respect to the crankshaft cranks (11, 12, 13, 14 ) of the other cylinder group in the circumferential direction offset by 180 ° on the crankshaft (15) are arranged. Internal combustion engine according to claim 1, characterized in that the exhaust gas lines (8) of the cylinder groups merge into partial exhaust gas lines (9) to form two integrated partial exhaust manifolds (7a, 7b) within the at least one cylinder head. Internal combustion engine according to claim 1 or 2, characterized in that the exhaust gas lines (8) of the cylinders (1, 2, 3, 4) merge to form an integrated exhaust manifold (7) within the at least one cylinder head to form an overall exhaust gas line (10). Internal combustion engine according to one of Claims 1 or 2, characterized in that the partial exhaust gas lines (9) of the cylinders (1, 2, 3, 4) merge outside the at least one cylinder head to form an overall exhaust gas line (10). Internal combustion engine according to one of the preceding claims, characterized in that the internal combustion engine is a naturally aspirated engine. Internal combustion engine according to one of claims 1 to 4, characterized in that at least one exhaust gas turbocharger is provided, which comprises a turbine disposed in the Abgasabführsystem (6). Internal combustion engine according to claim 6, characterized in that the turbine of the at least one exhaust gas turbocharger in the total exhaust gas line (10) is arranged. Internal combustion engine according to Claim 6, in which the partial exhaust gas lines (9) of the cylinders (1, 2, 3, 4) merge outside the at least one cylinder head to form an overall exhaust gas line (10), characterized in that the turbine of the at least one exhaust gas turbocharger is a double-flow turbine , the one Having inlet region with two inlet channels, wherein each one of the two partial exhaust gas lines (9) opens into one of the two inlet channels. Internal combustion engine according to claim 6, characterized in that two exhaust-gas turbochargers are provided which comprise two turbines arranged in the exhaust-gas removal system (6). Internal combustion engine according to claim 9, characterized in that the two turbines in the overall exhaust line (10) are arranged in series. Internal combustion engine according to Claim 9, in which the partial exhaust gas lines (9) of the cylinders (1, 2, 3, 4) merge outside the at least one cylinder head to form an overall exhaust gas line (10), characterized in that a turbine is provided in each of the two partial exhaust gas lines (9) is arranged. Internal combustion engine according to one of the preceding claims, characterized in that at least one exhaust aftertreatment system in the exhaust gas removal system (6) is provided. Internal combustion engine according to claim 12, characterized in that the at least one exhaust aftertreatment system in the overall exhaust line (10) is arranged. Internal combustion engine according to Claim 12, in which the partial exhaust gas lines (9) of the cylinders (1, 2, 3, 4) merge outside the at least one cylinder head to form an overall exhaust gas line (10), characterized in that an exhaust aftertreatment system is provided in each of the two partial exhaust gas lines (9) is arranged. Method for operating an internal combustion engine according to one of the preceding claims, characterized in that at the cylinders (1, 2, 3, 4), the combustion is initiated at a distance of 180 ° KW. A method according to claim 15 for operating an internal combustion engine, the cylinders (1, 2, 3, 4) of which are equipped with ignition devices for initiating spark ignition, characterized in that the cylinders (1, 2, 3, 4) are connected by means of ignition devices in the order of 1 - 3 - 2 - 4 and be ignited at a distance of 180 ° KW, the cylinders (1, 2, 3, 4) starting with an outer cylinder (1, 4) sequentially counted along the longitudinal axis of the at least one cylinder head and numbered. A method according to claim 15 for operating an internal combustion engine, the cylinders (1, 2, 3, 4) of which are equipped with ignition devices for initiating spark ignition, characterized in that the cylinders (1, 2, 3, 4) are connected by means of ignition devices in the order of 1 Are ignited at a distance of 180 ° KW, the cylinders (1, 2, 3, 4) beginning with an outer cylinder (1, 4) sequentially counted along the longitudinal axis of the at least one cylinder head and numbered.

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