EP2532869B1 - Combustion engine with four cylinders arranged in a row - Google Patents

Description

The invention relates to an internal combustion engine with at least one cylinder head with the features of the preamble of claim 1.

In the DE 10 2008 035 957 A1 an internal combustion engine is disclosed according to the preamble of claim 1.

From the DE 33 14 839 A1 a manifold device for a four-cylinder in-line engine is known, in which two exhaust pipes and thus the exhaust gases from the combustion chambers of two cylinders are brought together to form a partial exhaust pipe, with these two partial exhaust pipes then being combined.

From the US 2009 / 0 151 343 A1 a cylinder head for an internal combustion engine is known, with the exhaust pipes of a four-cylinder in-line engine being structurally integrated into the cylinder head. Each cylinder is equipped with two exhaust pipes, with two exhaust pipes being combined to form a partial exhaust pipe and the partial exhaust pipes shown in this way being continued in three separate exhaust gas discharge pipes. Two exhaust pipes of the two inner cylinders are brought together, the remaining exhaust pipes of the two inner cylinders being merged with the partial exhaust pipes of the two outer cylinders, so that a total of three exhaust gas discharge pipes are shown.

The literature reference Kuhlbach Kai, et al, "Cylinder head with integrated exhaust manifold for downsizing concepts" MTZ Motortechnike Zeitschrift, Vieweg Verlag, Wiesbaden, DE, Volume 70, No. 4 April 1, 2009, pages 286-293, XP001521558 ISSN: 0024-8525 only discloses generalized information on the concept of a structural combination of the cylinder head and exhaust pipes, whereby the exhaust manifolds, which are usually separately designed, are integrated into the cylinder head.

From the US 4,028,887 A a further exhaust system for an internal combustion engine is known, wherein the exhaust gases from two mutually adjacent cylinders are each combined in a partial exhaust line and the two partial exhaust lines are brought together in a reaction chamber outside a cylinder head, into which the cylinders and the partial exhaust lines are partially structurally integrated. The reaction chamber is intended to thermally process the exhaust gases through further oxidation of previously unburned gas components. The the US 4,028,887 A The measures that can be taken are aimed at maintaining a high temperature of the exhaust gases, with the aim of creating optimal reaction conditions in the reaction chamber mentioned, while at the same time limiting the thermal stress on the cylinder head.

Internal combustion engines have a cylinder block and at least one cylinder head, which are connected to each other to form the cylinders. The cylinder block has cylinder bores to accommodate the pistons or cylinder tubes. The pistons are guided axially movably in the cylinder tubes and, together with the cylinder tubes and the at least one cylinder head, form the combustion chambers of the internal combustion engine.

Modern internal combustion engines are almost exclusively operated using a four-cycle operating procedure. As part of the charge cycle, the combustion gases are pushed out via the outlet openings of at least four cylinders and the combustion chambers are filled with fresh mixture or charge air via the inlet openings. In order to control the gas exchange, an internal combustion engine requires control elements and actuating devices for actuating these control elements. To control the gas exchange, lift valves are almost exclusively used as control elements in four-stroke engines, which carry out an oscillating lifting movement during operation of the internal combustion engine and in this way release and close the inlet and outlet openings. The valve actuation mechanism required to move the valves, including the valves themselves, is called the valve train. The at least one cylinder head usually serves to accommodate this valve train.

It is the job of the valve train to release or close the inlet and outlet openings of the cylinders in a timely manner, with the aim of quickly releasing the largest possible flow cross sections in order to reduce throttling losses in the inlet and outlet. to keep the outflowing gas flows low and to ensure that the combustion chambers are filled as well as possible with fresh mixture or an effective, ie complete, removal of the exhaust gases.

The inlet channels, which lead to the inlet openings, and the outlet channels, i.e. H. According to the prior art, the exhaust pipes that connect to the exhaust openings are at least partially integrated in the cylinder head. The exhaust pipes of the cylinders are usually combined to form a common exhaust pipe or in groups to form several exhaust pipes. The combination of exhaust pipes to form an overall exhaust pipe is generally referred to as an exhaust manifold in the context of the present invention, whereby the section of the overall exhaust pipe, which lies upstream of a turbine that may be arranged in the overall exhaust pipe, can also be viewed as belonging to the exhaust manifold. In individual cases, the inlet area or the inlet housing of a turbine can also be viewed as belonging to the exhaust manifold, namely when the turbine is arranged close to the engine and a clear separation between the inlet area and the entire exhaust pipe cannot be made.

In the internal combustion engine, the exhaust pipes of four cylinders are combined to form a single exhaust pipe to form an exhaust manifold. The exhaust pipes of the cylinders are brought together in stages in such a way that the at least one exhaust pipe of an external cylinder and the at least one exhaust pipe of the adjacent internal cylinder merge to form a partial exhaust pipe and the two partial exhaust pipes of the four cylinders formed in this way to form an overall exhaust pipe merge. With this measure, the total distance of all exhaust pipes and thus the volume of the manifold can be significantly reduced. The designed exhaust manifold can be partially or completely integrated in the at least one cylinder head. The exhaust gas removal system exits on the outside of the cylinder head.

The evacuation of the combustion gases from a cylinder of the internal combustion engine as part of the charge cycle is essentially based on two different mechanisms. If the exhaust valve opens near bottom dead center at the beginning of the gas cycle, the combustion gases flow due to the towards the end of the Combustion in the cylinder prevailing high pressure levels and the associated high pressure difference between the combustion chamber and the exhaust tract at high speed through the outlet opening into the exhaust gas discharge system. This pressure-driven flow process is accompanied by a high pressure peak, which is also referred to as a pre-exhaust surge and propagates along the exhaust pipe at the speed of sound, with the pressure decreasing, i.e. reducing, to a greater or lesser extent as the distance increases and depending on the pipe routing due to friction.

As the gas cycle continues, the pressures in the cylinder and in the exhaust pipe largely equalize, so that the combustion gases are pushed out largely as a result of the stroke movement of the piston.

The dynamic wave processes or pressure fluctuations in the exhaust gas removal system are the reason why the offset cylinders of a multi-cylinder internal combustion engine can influence one another during the charge change, and in particular can also hinder one another. The result can be a deteriorated torque characteristic or a reduced power offering. If the exhaust pipes of the individual cylinders are separated from one another for a longer distance, the mutual influence of the cylinders during the gas cycle can be counteracted.

It must be taken into account that pressure fluctuations in gaseous media propagate as waves, which run through the exhaust pipes and are reflected at open or closed pipe ends. The exhaust gas flow or the local exhaust gas pressure in the exhaust gas removal system then results from the superposition of the leading and reflected waves. Depending on the specific design of the exhaust gas removal system, the pressure waves that emanate from a cylinder run not only through the at least one exhaust line of this cylinder, but also along the exhaust lines of the other cylinders, possibly up to the outlet opening provided at the end of the respective line .

Exhaust gas that has already been pushed out or discharged into an exhaust gas line during the gas exchange can thus enter the cylinder again as a result of the pressure wave emanating from another cylinder.

It proves to be disadvantageous, for example, if there is excess pressure at the outlet opening of a cylinder towards the end of the gas cycle or the pressure wave from another cylinder spreads along the exhaust pipe towards the outlet opening, which counteracts the evacuation of the combustion gases from this cylinder. In this phase of the gas exchange, the combustion gases are largely expelled as a result of the stroke movement of the piston.

Problems with the gas exchange of a multi-cylinder internal combustion engine arise particularly at low speeds when, during a valve overlap in which the exhaust valve is not yet closed when the inlet valve is open, the exhaust gas has to be flushed out of the cylinder as much as possible while accepting scavenging losses. On the one hand, this leads to poorer efficiency, but on the other hand, to a larger cylinder filling and thus to higher performance. Variable valve timing allows the valve overlap to be varied depending on the speed.

The problem described above regarding the mutual influence of the cylinders during the gas exchange, which results from the dynamic wave processes taking place in the exhaust gas removal system and which can cause a deterioration in the torque characteristics, is of increasing relevance in the structural design of internal combustion engines. The reasons are as follows.

For several reasons, it is advantageous to integrate the exhaust manifold as far as possible into the at least one cylinder head, i.e. H. The combination of the exhaust pipes to form a complete exhaust pipe should be carried out as extensively as possible in the cylinder head.

This leads to a more compact design of the internal combustion engine and allows dense packaging of the entire drive unit in the engine compartment. There are also cost advantages in production and assembly and a reduction in the weight of the internal combustion engine, especially when the exhaust manifold is completely integrated into the cylinder head.

Furthermore, the greatest possible integration of the combination of the exhaust pipes can have an advantageous effect on the arrangement and operation of an exhaust gas aftertreatment system, which is provided downstream of the manifold. The The path of the hot exhaust gases to the various exhaust gas aftertreatment systems should be as short as possible so that the exhaust gases are given little time to cool down and the exhaust gas aftertreatment systems reach their operating temperature or light-off temperature as quickly as possible, especially 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 opening on the cylinder and the exhaust gas aftertreatment system, which can be achieved by reducing the mass and length of this section. The greatest possible integration of the exhaust manifold into the cylinder head can be effective.

In internal combustion engines charged using exhaust gas turbochargers, the aim is to have the turbine as close as possible to the outlet, i.e. H. the exhaust openings of the cylinders, in order to be able to optimally use the exhaust gas enthalpy of the hot exhaust gases, which is largely determined by the exhaust gas pressure and the exhaust gas temperature, and to ensure a quick response of the turbocharger. The thermal inertia and the volume of the line system between the exhaust openings of the cylinders and the turbine should also be minimized, which is why the greatest possible integration of the exhaust manifold into the cylinder head is expedient.

The greatest possible integration of the exhaust manifold into the cylinder head has - as explained above - a number of advantages, but in addition to shortening the total distance of all exhaust pipes, it also leads to a shortening of the individual exhaust pipes, since these are already brought together immediately downstream of the exhaust openings, which solves the problem the mutual influence of the cylinders during gas exchange.

Compensating for the shortening of the exhaust pipes caused by the greatest possible integration into the cylinder head by making the cylinder head wider - perpendicular to the longitudinal axis of the cylinder head - is only possible to a limited extent, as there are strict limits to this approach for reasons of crash behavior, in particular sufficient space in the engine compartment must be available for unhindered deformation.

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, i.e. H. of the generic type, which has a compact design and with which the problem of the mutual influence of the cylinders during gas exchange can be eliminated or alleviated.

The first task is solved by an internal combustion engine with at least one cylinder head with the features of claim 1.

• vier entlang der Längsachse des Zylinderkopfes in Reihe angeordnete Zylinder aufweist, wobei jeder Zylinder mindestens eine Auslaßöffnung zum Abführen der Abgase aus dem Zylinder via Abgasabführsystem aufweist, wozu sich an jede Auslaßöffnung eine Abgasleitung anschließt, wobei
• die Abgasleitungen der Zylinder stufenweise zu einer Gesamtabgasleitung zusammenführen, wobei jeweils die mindestens eine Abgasleitung eines außenliegenden Zylinders und die mindestens eine Abgasleitung des benachbarten innenliegenden Zylinders jeweils innerhalb des mindestens einen Zylinderkopfes zu einer Teilabgasleitung zusammenführen, bevor die beiden Teilabgasleitungen der vier Zylinder zu einer Gesamtabgasleitung zusammenführen, wobei
• das Abgasabführsystem an einer Außenseite des Zylinderkopfes austritt, und wobei
• die außenliegenden Wandabschnitte, die jeweils abschnittsweise die mindestens eine Abgasleitung eines außenliegenden Zylinders und die mindestens eine Abgasleitung des benachbarten innenliegenden Zylinders voneinander trennen und in das Abgasabführsystem hineinragen, sich in Richtung der Außenseite des Zylinderkopfes senkrecht zur Längsachse des Zylinderkopfes weniger weit erstrecken als der innenliegende Wandabschnitt, der abschnittsweise die beiden Teilabgasleitungen und die Abgasleitungen der beiden innenliegenden Zylinder voneinander trennt und in das Abgasabführsystem hineinragt, und die dadurch gekennzeichnet ist, dass
  sowohl der innenliegende Wandabschnitt als auch die außenliegenden Wandabschnitte einteilig mit dem Zylinderkopf ausgebildet sind, wobei die Teilabgasleitungen außerhalb des mindestens einen Zylinderkopfes zu einer Gesamtabgasleitung zusammenführen, und wobei sich der innenliegende Wandabschnitt, welcher in das Abgasabführsystem hineinragt, bis zur Außenseite des mindestens einen Zylinderkopfes oder über die Außenseite des mindestens einen Zylinderkopfes hinaus erstreckt.

An internal combustion engine with at least one cylinder head is shown

• has four cylinders arranged in series along the longitudinal axis of the cylinder head, each cylinder having at least one outlet opening for discharging the exhaust gases from the cylinder via an exhaust gas removal system, for which purpose an exhaust gas line is connected to each outlet opening, whereby
• gradually merging the exhaust pipes of the cylinders to form a total exhaust pipe, with the at least one exhaust pipe of an external cylinder and the at least one exhaust pipe of the adjacent internal cylinder each merging within the at least one cylinder head to form a partial exhaust pipe before the two partial exhaust pipes of the four cylinders merge to form an overall exhaust pipe , where
• the exhaust gas discharge system exits on an outside of the cylinder head, and where
• the outer wall sections, which each sectionally separate the at least one exhaust line of an outer cylinder and the at least one exhaust line of the adjacent inner cylinder from one another and protrude into the exhaust gas discharge system, extend less far in the direction of the outside of the cylinder head perpendicular to the longitudinal axis of the cylinder head than the inner wall section , which in sections separates the two partial exhaust pipes and the exhaust pipes of the two internal cylinders from each other and protrudes into the exhaust gas discharge system, and which is characterized in that
  both the inner wall section and the outer wall sections are formed in one piece with the cylinder head, the Partial exhaust pipes outside the at least one cylinder head merge to form a total exhaust pipe, and the inner wall section, which protrudes into the exhaust gas discharge system, extends to the outside of the at least one cylinder head or beyond the outside of the at least one cylinder head.

In a first stage, the exhaust pipes of the four cylinders of the at least one cylinder head of the internal combustion engine are grouped, i.e. H. in pairs, brought together, with an external cylinder and the adjacent internal cylinder forming a pair of cylinders, the exhaust pipes of which merge to form a partial exhaust pipe. In a second stage, these partial exhaust pipes are then merged downstream in the exhaust gas discharge system to form an overall exhaust pipe. This shortens the total distance of all exhaust pipes. The gradual merging of the exhaust pipes into one overall exhaust pipe also contributes to a more compact, i.e. H. less voluminous design.

This is achieved through a constructive, i.e. H. objective feature of the internal combustion engine, namely in that the outer wall sections, which each separate the exhaust pipes of a pair of cylinders from one another in sections, extend less far in the direction of the outside of the cylinder head perpendicular to the longitudinal axis of the cylinder head than the inner wall section, which in sections separates the two partial exhaust pipes of the two Separates cylinder pairs from each other.

The exhaust gas flows of the two cylinder groups are kept separated from each other for longer than the exhaust gas flows within a group. In this respect, there is a fundamental possibility that the cylinders in a group will continue to influence each other during gas exchange. However, the design of the partial exhaust pipes and their long separation from one another have the effect that one group of cylinders does not hinder the other group of cylinders during the gas exchange, or at least to a lesser extent. This alleviates the problem of the cylinders influencing each other during the gas exchange.

It is clear that the cylinders of a group could influence each other during the gas cycle due to the design of the internal combustion engine less critical, since this circumstance can be counteracted by an additional measure, namely by choosing a suitable ignition sequence.

In the case of an internal combustion engine with external ignition, variants can be advantageous in which the internal combustion engine is operated with the ignition sequence 1 - 2 - 4 - 3 instead of igniting the cylinders according to the conventional ignition sequence 1 - 3 - 4 - 2 at a distance of 180 ° CA . Starting from the first cylinder, the ignition times, measured in °CA, are the following: 0 - 180 - 360 - 540. In contrast to the conventional pattern, the cylinders of a cylinder group are fired immediately one behind the other, so that these cylinders have a thermodynamic offset of 180°CA.

The numbering of the cylinders of an internal combustion engine is regulated in DIN 73021. In in-line engines, the cylinders are counted one after the other, starting on the side opposite the clutch.

An internal combustion engine can also have two cylinder heads, for example if the cylinders are distributed over two cylinder banks. The combination of the exhaust pipes in the two cylinder heads can then also be used to improve the gas exchange and to improve the torque available.

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 into the at least one cylinder head, i.e. H. The exhaust pipes should be brought together as extensively as possible in the cylinder head, as this leads to a more compact design, allows dense packaging and results in cost and weight advantages. In addition, there may be advantages in terms of the response behavior of an exhaust gas turbocharger or an exhaust gas aftertreatment system provided in the exhaust gas discharge system.

As already mentioned, the at least one exhaust pipe of an external cylinder and the at least one exhaust pipe of the adjacent internal cylinder each lead together within the at least one cylinder head to form a partial exhaust pipe.

I.e. According to the embodiment in question, the exhaust pipes of each of the two cylinder groups are brought together to form a partial exhaust pipe belonging to this cylinder group within the cylinder head.

Embodiments of the internal combustion engine are advantageous in which the inner wall section extends in the direction of the outside of the at least one cylinder head perpendicular to the longitudinal axis of the at least one cylinder head by a distance Δ s further than the outer wall sections, whereby: Δ s ≥ 5 mm.

Computer-aided simulations have shown that in individual cases a satisfactory torque characteristic can already be achieved if the inner wall section extends 5 mm or more beyond the outer wall sections in the direction of the outside of the at least one cylinder head, the distance Δ s being perpendicular to the longitudinal axis of the at least a cylinder head is measured and the point of a wall section that projects furthest towards the outside into the exhaust gas discharge system serves as a reference point.

The further the inner wall section extends beyond the outer wall sections, the more pronounced is the separation of the two partial exhaust pipes from one another and the more noticeable is the effect achieved in that the cylinder groups do not influence each other or influence each other to a lesser extent during the gas exchange, in particular do not hinder them .

Embodiments of the internal combustion engine in which the following applies: Δ s ≥ 10 mm are therefore particularly advantageous.

Embodiments of the internal combustion engine are advantageous in which the free end of the inner wall section, which projects into the exhaust gas discharge system, has a distance Δ d from the outside of the at least one cylinder head, which runs perpendicular to the longitudinal axis of the at least one cylinder head, whereby: Δ d ≤ 30 mm , preferably Δ d ≤ 20 mm.

Embodiments of the internal combustion engine in which the following applies: Δ d ≥ 10 mm are also advantageous in this context.

It is inherent in the above embodiment that the partial exhaust pipes formed in the cylinder head are already brought together within the cylinder head to form an overall exhaust pipe. In this respect, the entire exhaust gas carried by the exhaust gas removal system leaves the cylinder head through a single outlet opening on the exhaust-side outside of the cylinder head.

The present embodiment is characterized by a very compact design that has all the advantages that an exhaust manifold that is completely integrated into the cylinder head brings with it.

Embodiments of the internal combustion engine are advantageous in which the free end of the inner wall section, which projects into the exhaust gas discharge system, is a distance Δ perpendicular to plane A from a plane A, which runs parallel to the outside of the at least one cylinder head and through the exhaust openings of the cylinders L has with Δ L ≥ D , where D is the diameter of a cylinder. It is assumed that the outside is perpendicular to a mounting plane on which the at least one cylinder head can be connected to a cylinder block. Otherwise, plane A is not parallel to the outside, but rather perpendicular to this mounting plane.

Embodiments of the internal combustion engine in which the following applies: Δ L ≥ 1.2D are particularly advantageous.

Plane A is considered to pass through the exhaust ports of the cylinders if plane A intersects the center lines of the exhaust ports, i.e. H. includes the centers of the outlet openings.

The distance Δ L largely determines the distance over which the exhaust gas flows of the partial exhaust pipes are separated from one another. The larger the distance Δ L is chosen, the greater the length of the partial exhaust pipes and the less the cylinders can influence each other during the gas cycle.

For the reasons already mentioned, embodiments of the internal combustion engine are advantageous in which the exhaust pipes of the cylinders merge to form an integrated exhaust manifold within the at least one cylinder head to form an overall exhaust pipe.

As already mentioned, the exhaust pipes of the cylinders merge outside the at least one cylinder head to form an overall exhaust pipe. The exhaust pipes of the cylinders are also brought together within the cylinder head to form partial exhaust pipes, with these partial exhaust pipes being merged outside the at least one cylinder head to form an overall exhaust pipe. The exhaust manifold is then constructed in a modular manner and is composed of a manifold section integrated in the cylinder head and an external manifold or manifold section.

In addition to the measures described, the dynamic wave processes occurring in the exhaust gas discharge system may require an external manifold or external manifold section in order to optimize the gas exchange and in this way ensure a satisfactory torque characteristic.

As already mentioned, the inner wall section, which projects into the exhaust gas discharge system, extends to the outside of the at least one cylinder head.

In the present case, the exhaust gas flows of the partial exhaust pipes are separated from one another by the inner wall section until they leave the cylinder head, so that the exhaust gas discharge system exits the cylinder head in the form of two outlet openings. The exhaust pipes of the cylinders or the partial exhaust pipes are brought together downstream of the cylinder head and thus only outside the cylinder head to form an overall exhaust pipe.

As already mentioned, the inner wall section, which projects into the exhaust gas discharge system, extends beyond the outside of the at least one cylinder head. According to this embodiment, the exhaust gas flows of the partial exhaust pipes are separated from one another by the inner wall section even after leaving the cylinder head.

In this embodiment of the internal combustion engine, too, the exhaust gas removal system emerges from the cylinder head in the form of two outlet openings.

The inner wall section is formed in one piece with the at least one cylinder head, with the wall section protruding from the cylinder head in the unassembled state of the internal combustion engine and protruding outwards. Alternatively, the inner wall section can also be constructed modularly, but this is not covered by the scope of protection of the main claim, with a first section being formed by the at least one cylinder head and a further section continuing the first section being formed by an external manifold section. The inlet housing of a turbine arranged in the overall exhaust pipe can also serve to form the inner wall section, i.e. H. be used and form the further section. In the latter two embodiments, the section formed by the external manifold section or the inlet housing can also protrude into the cylinder head.

Internal combustion engines of the type described are particularly suitable for charging by means of exhaust gas turbocharging, whereby the at least one turbine should be arranged as close as possible to the engine. In this respect, internal combustion engines with at least one exhaust gas turbocharger are advantageous, with the turbine of the at least one exhaust gas turbocharger being arranged in the overall exhaust line and having an inlet area for supplying the exhaust gases. This means that all of the exhaust gas from the four cylinders is fed to the turbine.

The advantages of an exhaust gas turbocharger, for example compared to a mechanical supercharger, are that no mechanical connection for power transmission between the supercharger and the internal combustion engine exists or is required. While a mechanical supercharger obtains the energy required to drive it entirely from the internal combustion engine, the exhaust gas turbocharger uses the exhaust energy of the hot exhaust gases. The energy delivered to the turbine by the exhaust gas flow is used to drive a compressor, which conveys and compresses the charge air supplied to it, thereby charging the cylinders. If necessary, charge air cooling is provided to cool the compressed combustion air before it enters the cylinders.

The primary purpose of charging is to increase the performance of the internal combustion engine. However, supercharging is also a suitable means of shifting the load spectrum towards higher loads under the same vehicle conditions, which can reduce specific fuel consumption.

A drop in torque is often observed when the engine speed falls below a certain level. Attempts are made to improve the torque characteristics of a turbocharged internal combustion engine using various measures. For example, by making the turbine cross-section small and simultaneously blowing off exhaust gases. Such a turbine is also known as a waste gate turbine. If the exhaust gas mass flow exceeds a critical size, part of the exhaust gas flow is guided past the turbine or the turbine impeller by means of a bypass line by opening a shut-off element as part of the so-called exhaust gas blow-off.

The torque characteristics of a turbocharged internal combustion engine can also be determined by several turbochargers arranged in parallel or in series, i.e. H. can be improved by several turbines arranged in parallel or in series.

The turbine can also be equipped with a variable turbine geometry, which allows further adaptation to the respective operating point of the internal combustion engine by adjusting the turbine geometry or the effective turbine cross section. Adjustable guide vanes are arranged in the inlet area of the turbine to influence the direction of flow. In contrast to the blades of the rotating impeller, the guide blades do not rotate with the shaft of the turbine.

If the turbine has a fixed, unchangeable geometry, the guide vanes are not only stationary, but also completely immovable in the inlet area, i.e. H. rigidly fixed. With a variable geometry, on the other hand, the guide blades are arranged stationary, but are not completely immovable, but can be rotated about their axis, so that the flow against 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. In particular Turbocharged internal combustion engines are subject to higher thermal loads than naturally aspirated engines, which is why higher demands are placed on cooling.

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

Liquid cooling requires the internal combustion engine to be equipped, i.e. H. the cylinder head or cylinder block, with an integrated coolant jacket, i.e. H. the arrangement of coolant channels leading the coolant through the cylinder head or cylinder block. The heat is transferred inside the component to the coolant, usually water mixed with additives. The coolant is pumped using a pump arranged in the cooling circuit so that it circulates in the coolant jacket. In this way, the heat given off to the coolant is removed from the interior of the head or block and removed from the coolant again in a heat exchanger.

In internal combustion engines charged by means of exhaust gas turbocharging, in which the turbine of the at least one exhaust gas turbocharger is arranged in the overall exhaust pipe and has an inlet area for supplying the exhaust gases, embodiments are advantageous which are characterized in that the inner wall section, which projects into the exhaust gas discharge system, is advantageous extends into the inlet area of the turbine.

As already described, the inner wall section can in principle and also in connection with the above-mentioned embodiment be formed in one piece with the at least one cylinder head.

However, embodiments can also be advantageous, but are not covered by the scope of protection of the main claim, in which the inner wall section is constructed modularly, with the at least one cylinder head forming a partial section and the inlet area of the turbine forming a further partial section. Reference is made to the statements made above regarding the design of the inner wall section.

Also not covered by the scope of protection of the main claim are embodiments in which the internal wall section has a modular structure, with the at least one cylinder head forming a partial section and an external manifold section forming a further partial section.

Embodiments of the internal combustion engine in which each cylinder has at least two outlet openings for discharging the exhaust gases from the cylinder are advantageous.

As has already been stated, the aim is to quickly release the largest possible flow cross sections during the gas exchange in order to keep the throttling losses in the outflowing exhaust gas flows low and to ensure effective removal of the exhaust gases. It is therefore advantageous to equip the cylinders with two or more exhaust openings.

In a further aspect, a method for operating an internal combustion engine according to a previously described type is shown, the cylinders of which are equipped with ignition devices to initiate spark ignition, the cylinders being ignited in the order 1 - 2 - 4 - 3, the cylinders starting with an external cylinder are counted and numbered in sequence along the longitudinal axis of the at least one cylinder head.

What was said in connection with the internal combustion engine according to the invention also applies to the method.

Fig. 1

schematisch eine erste Ausführungsform des Zylinderkopfes im Querschnitt,

Fig. 2

schematisch eine zweite Ausführungsform des Zylinderkopfes im Querschnitt, und

Fig. 3

schematisch eine dritte Ausführungsform des Zylinderkopfes im Querschnitt.

The invention is explained below using three exemplary embodiments according to Figures 1 to 3 described in more detail. This shows:

Fig. 1

schematically a first embodiment of the cylinder head in cross section,

Fig. 2

schematically a second embodiment of the cylinder head in cross section, and

Fig. 3

schematically a third embodiment of the cylinder head in cross section.

Figure 1 shows schematically and in section a first embodiment of the cylinder head 1 together with a section of the inlet housing 11 of a turbine 12.

The cylinder head 1 has four cylinders 3, which run along the longitudinal axis 2 of the cylinder head 1, i.e. H. are arranged in series. The cylinder head 1 thus has two external cylinders 3a and two internal cylinders 3b.

Each cylinder 3 has two outlet openings 4, to which exhaust pipes 5 of the exhaust gas discharge system are connected for discharging the exhaust gases. The exhaust pipes 5 of the cylinders 3 gradually merge to form a total exhaust pipe 7, with the two exhaust pipes 5 of an external cylinder 3a and the two exhaust pipes 5 of the adjacent internal cylinder 3b merging to form a partial exhaust pipe 6 belonging to this pair of cylinders, before the two partial exhaust pipes 6 of the four Bring cylinders 3, 3a, 3b together to form an overall exhaust pipe 7.

The two exhaust pipes 5 of an external cylinder 3a and the two exhaust pipes 5 of the adjacent internal cylinder 3b are separated from each other in sections by an external wall section 9a, which protrudes into the exhaust gas discharge system, and the two partial exhaust pipes 6 and the exhaust pipes 5 of the two internal cylinders 3b in sections through an internal wall section 9b, which also projects into the exhaust gas discharge system. Both the inner wall section 9b and the outer wall sections 9a are formed in one piece with the cylinder head 1.

The outer wall sections 9a extend less far towards the outside 8 of the cylinder head 1 than the inner wall section 9b. The inner wall section 9b extends in the direction of the outside 8 of the cylinder head 1 - perpendicular to the longitudinal axis 2 of the cylinder head 1 - by a distance Δ s further than the outer wall sections 9a. The inner wall section 9b projects beyond the outer wall sections 9a by the distance Δ s .

At the in Figure 1 In the embodiment shown, the inner wall section 9b extends with the free end 9c to the outside 8 of the cylinder head 1, so that the exhaust gas flows of the partial exhaust pipes 6 until they leave the cylinder head 1 through the inner wall section 9b are separated from each other and the exhaust gas discharge system emerges from the cylinder head 1 in the form of two outlet openings. The exhaust pipes 5 of the cylinders 3 or the partial exhaust pipes 6 of the cylinder pairs are only brought together outside the cylinder head 1 to form a total exhaust pipe 7.

In this respect, the exhaust manifold 10 is only partially integrated in the cylinder head 1. The manifold section 10b located inside the cylinder head 1 is replaced by a manifold section 10a located outside the cylinder head 1, i.e. H. an external manifold section 10a, supplemented.

The turbine 12 of an exhaust gas turbocharger is arranged in the overall exhaust line 7 and is equipped with an inlet region 11 for supplying the exhaust gases to the cylinders 3. The entire exhaust line 7 or the exhaust manifold 10 merges smoothly into the inlet housing 11 of the turbine 12, which is due to the arrangement of the turbine 12 close to the engine.

Figure 2 shows schematically and in section an embodiment of the cylinder head 1 together with a section of the inlet housing 11 of a turbine 12. Only the differences from that in Figure 1 illustrated embodiment are discussed, which is why reference is also made to Figure 1 . The same reference numbers were used for the same components.

In contrast to the embodiment of Figure 1 the inner wall section 9b extends at the in Figure 2 illustrated embodiment beyond the outside 8 of the cylinder head 1 and into the inlet area 11 of the turbine 12.

The inner wall section 9b has a modular structure, which is not covered by the scope of protection of the main claim, with the cylinder head 1 forming a first section 9b' and the inlet region 11 of the turbine 12 forming a further section 9b", which continues the first section 9b' .

In this embodiment too, the exhaust gas removal system exits the cylinder head 1 in the form of two outlet openings. The exhaust gas flows from the partial exhaust pipes 6 continue to flow through the internal cylinder head 1 even after it leaves Wall section 9b, 9b" separated from each other. The overall exhaust pipe 7 is formed in the present case by the inlet housing 11 of the turbine 12.

The end of the first section 9b', which projects into the exhaust gas discharge system, is at a distance from the outside 8 of the cylinder head 1, which is why the section 9b" formed by the inlet housing 11 protrudes into the cylinder head 1 in order to continue the first section 9b' can.

Figure 3 shows schematically and in section an embodiment of the cylinder head 1 that is not included in the scope of protection of the main claim. Only the differences from that in Figure 1 illustrated embodiment are discussed, which is why reference is also made to Figure 1 . The same reference numbers were used for the same components.

In contrast to the embodiment of Figure 1 the inner wall section 9b extends at the in Figure 3 illustrated embodiment does not extend to the outside 8 of the cylinder head 1. Rather, the free end 9c of the inner wall section 9b has a distance Δ d from the outside 8 of the cylinder head 1.

Consequently, the exhaust pipes 5 of the cylinders 3 come together within the cylinder head 1 to form an integrated exhaust manifold 10 to form an overall exhaust pipe 7. The exhaust gas removal system exits the cylinder head 1 in the form of a single opening.

The free end 9c of the inner wall section 9b has a distance Δ L that runs perpendicular to the plane A from a plane A, which runs parallel to the outside 8 of the cylinder head 1 and through the exhaust openings of the cylinders.

Reference symbols

1

cylinder head

2

Longitudinal axis of the cylinder head

3

cylinder

3a

external cylinder

3b

internal cylinder

4

outlet opening

5

Exhaust pipe

6

Partial exhaust pipe

7

Total exhaust pipe

8th

exhaust side outside of the cylinder head

9a

external wall section

9b

internal wall section

9b'

Part of the internal wall section

9b"

another section of the internal wall section

9c

free end of the inner wall section

10

exhaust manifold

10a

Exhaust manifold section located outside the cylinder head

10b

Exhaust manifold section located within the cylinder head

11

Inlet housing or inlet area of the turbine

12

turbine

°KW

degrees crank angle

A

Plane that runs parallel to the outside and through the exhaust ports of the cylinders

D

Diameter of a cylinder

Δd

Distance of the free end of the inner wall section from the outside of the cylinder head

ΔL

Distance of the free end of the internal wall section from plane A

Δs

Distance that the internal wall section extends beyond an external wall section

Claims (7)

1. Internal combustion engine having at least one cylinder head (1), which

   - has four cylinders (3) arranged in series along the longitudinal axis (2) of the cylinder head (1), each cylinder (3) having at least one exhaust port (4) for discharging the exhaust gases from the cylinder (3) via an exhaust system, for which purpose each exhaust port (4) is adjoined by an exhaust line (5); wherein

   - the exhaust lines (5) of the cylinders (3) come together in stages to form an overall exhaust line (7), the at least one exhaust line (5) of an outer cylinder (3a) and the at least one exhaust line (5) of the adjacent inner cylinder (3b) in each case coming together to form a partial exhaust line (6) within the at least one cylinder head (1) before the two partial exhaust lines (6) of the four cylinders (3, 3a, 3b) come together to form an overall exhaust line (7); wherein

   - the exhaust system emerges at an outer side (8) of the cylinder head (1); and wherein

   - the outer wall sections (9a), which in each case separate a section of the at least one exhaust line (5) of an outer cylinder (3a) and a section of the at least one exhaust line (5) of the adjacent inner cylinder (3b) from one another and which project into the exhaust system, extend less far in the direction of the outer side (8) of the cylinder head (1), perpendicularly to the longitudinal axis (2) of the cylinder head (1), than the inner wall section (9b), which separates a section of the two partial exhaust lines (6) and a section of the exhaust lines (5) of the two inner cylinders (3b) from one another and projects into the exhaust system, characterized in that

   the inner wall section (9b) as well as the outer wall sections (9a) are formed integrally with the cylinder head (1), wherein the partial exhaust lines (6) outside the at least one cylinder head (1) come together to form an overall exhaust line (7), and wherein the inner wall section (9b), which projects into the exhaust system, extends up to the outer side (8) of the at least one cylinder head (1) or beyond the outer side (8) of the at least one cylinder head (1).
2. Internal combustion engine according to Claim 1, characterized in that the inner wall section (9b) extends further in the direction of the outer side (8) of the at least one cylinder head (1), perpendicularly to the longitudinal axis (2) of the at least one cylinder head (1), than the outer wall sections (9a) by a distance Δs, where Δs ≥ 5 mm.
3. Internal combustion engine according to Claim 2, characterized in that Δs ≥ 10 mm.
4. Internal combustion engine according to one of the preceding claims, characterized in that the free end (9c) of the inner wall section (9b), which projects into the exhaust system, is at a perpendicular distance ΔL from a plane A, which runs parallel to the outer side (8) of the at least one cylinder head (1) and through the exhaust ports (4) of the cylinders (3), where ΔL ≥ D, in which D is the diameter of a cylinder (3).
5. Internal combustion engine according to Claim 4, characterized in that ΔL ≥ 1.2D.
6. Internal combustion engine according to one of the preceding claims, having at least one exhaust turbocharger, the turbine (12) of the at least one exhaust turbocharger being arranged in the overall exhaust line (7) and having an inlet region (11) for the feeding in of the exhaust gases.
7. Internal combustion engine according to Claim 6, characterized in that the inner wall section (9b), which projects into the exhaust system, extends into the inlet region (11) of the turbine (12).

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