EP2172635A1 - Cylinder head for an internal combustion engine with two integrated exhaust manifolds and method to operate an internal combustion engine with such a cylinder head - Google Patents

Abstract

A cooling jacket is partially integrated in the cylinder head. Individual exhaust ducts (4a,4b) adjoin the exhaust ports (3b) of cylinders. An outer combined duct (6') is coupled to individual exhaust ducts. The outer combined duct is separated from individual exhaust ducts of inner cylinders by cooling jacket.

Description

• mindestens zwei Zylinder in der Art konfiguriert sind, dass sie zwei Gruppen mit jeweils mindestens einem Zylinder bilden, und
• die Abgasleitungen der Zylinder jeder Zylindergruppe unter Ausbildung eines integrierten Abgaskrümmers innerhalb des Zylinderkopfes jeweils zu einer Gesamtabgasleitung zusammenführen.

The invention relates to a cylinder head which is connectable to a cylinder block at a mounting end face, with an integrated at least partially in the cylinder head coolant jacket and at least two cylinders, each cylinder having at least one outlet opening for discharging the exhaust gases from the cylinder and to each outlet opening an exhaust pipe connects, and in the

• at least two cylinders are configured to form two groups each having at least one cylinder, and
• the exhaust gas lines of the cylinders of each cylinder group combine to form an integrated exhaust manifold within the cylinder head each to an overall exhaust gas line.

Furthermore, the invention relates to a method for operating an internal combustion engine with a cylinder head of the aforementioned type having at least three cylinders.

In the context of the present invention, the term internal combustion engine includes diesel engines, gasoline engines, but also hybrid internal combustion engines.

Internal combustion engines have a cylinder block and a cylinder head, which is used to form the individual cylinder d. H. Combustion chambers are connected to each other, wherein bores are provided for connecting in the cylinder head and in the cylinder block. As part of the assembly of the cylinder block and the cylinder head are arranged by stacking their mounting end faces in such a way to each other that the holes are aligned. By means of threaded bolts which are inserted and screwed into the bores of the cylinder head and the cylinder block, a connection is then made.

The cylinder block has a corresponding number of cylinder bores for receiving the pistons or the cylinder tubes. The pistons are axially movable in the cylinder tubes and form together with the cylinder tubes and the cylinder head the combustion chambers of the internal combustion engine. Consequently, a combustion chamber is mitbegrenzt each of a piston, a cylinder tube and the cylinder head and mitgestaltet. To seal the combustion chambers, a seal is usually arranged between the cylinder block and the cylinder head.

The cylinder head is usually used to hold the valve train. In order to control the charge cycle, an internal combustion engine requires control means and actuators to operate these controls. As part of the charge exchange, the expulsion of the combustion gases via the outlet openings and the filling of the combustion chamber d. H. the suction of the fresh mixture or the fresh air through the inlet openings. 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 required for the movement of the valves valve actuating mechanism including the valves themselves is referred to as a valve train.

It is the task of the valve train to open the intake and exhaust ports of the combustion chamber 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 the Combustion chamber with fresh mixture or an effective ie To ensure complete removal of the exhaust gases. Therefore, in the prior art, combustors are also frequently and increasingly equipped with two or more inlet or outlet ports.

The inlet ducts leading to the inlet openings and the outlet ducts or exhaust ducts adjoining the outlet openings are at least partially integrated in the cylinder head according to the prior art. If a cylinder has two or more outlet openings, the exhaust lines of the outlet openings of a single cylinder are usually combined to form a partial exhaust gas line belonging to the cylinder, whereby the partial exhaust gas lines can then be combined to form a common total exhaust gas line or in groups to form two or more total exhaust gas lines. The merger of exhaust pipes to one Total exhaust gas is referred to in the context of the present invention as the exhaust manifold.

Downstream of a manifold, the exhaust gases are then optionally supplied to the turbine of an exhaust gas turbocharger and / or one or more exhaust aftertreatment systems.

It is on the one hand endeavored to arrange the exhaust gas turbocharger or the closest possible to the outlet of the engine to optimally use in this way the exhaust enthalpy of the hot exhaust gases, which is largely determined by the exhaust pressure and the exhaust gas temperature, and a quick response of the turbocharger to ensure. On the other hand, the way the hot exhaust gases to the various exhaust aftertreatment systems should be as short as possible, so that the exhaust gases are given little time to cool and the exhaust aftertreatment systems reach their operating temperature or light-off as soon as possible, especially after a cold start of the engine.

In this context, it is therefore fundamentally endeavored to minimize the thermal inertia of the portion of the exhaust pipe between exhaust port on the cylinder and exhaust aftertreatment system or between exhaust port on the cylinder and turbocharger or turbine, which can be achieved by reducing the mass and the length of this section.

In order to achieve the aforementioned objects, according to a prior art approach, the exhaust pipes are merged within the cylinder head. This measure also allows the densest possible packaging of the drive unit. A cylinder head, in which the exhaust pipes of the cylinder are brought together within the cylinder head, is also the subject of the present invention.

In the cylinder head according to the invention also at least two cylinders are configured in such a way that they form two groups each having at least one cylinder, wherein the exhaust gas lines of the cylinders of each cylinder group merge to form an integrated exhaust manifold within the cylinder head to form an overall exhaust gas line. The cylinder head can additionally have cylinders that none Belong cylinder group, wherein a cylinder group may include only a single cylinder.

The groupwise merging of the exhaust pipes d. H. the provision of two total exhaust lines offers, inter alia, the possibility of supplying two exhaust gas turbochargers arranged in parallel or a double-flow turbine advantageously with exhaust gas, as will be discussed below.

However, a cylinder head with integrated exhaust manifolds is thermally more heavily loaded than a conventional cylinder head, which is equipped with an external manifold, and therefore makes increased demands on the cooling.

The heat released during combustion by the exothermic, chemical conversion of the fuel is partly dissipated via the walls delimiting the combustion chamber to the cylinder head and the cylinder block and partly via the exhaust gas flow to the adjacent components and the environment. In order to keep the thermal load of the cylinder head within limits, a portion of the introduced into the cylinder head heat flow must be withdrawn from the cylinder head again. The amount of heat dissipated from the surface of the internal combustion engine via radiation and heat conduction to the environment is not sufficient for efficient cooling, which is why cooling of the cylinder head is usually brought about deliberately by means of forced convection.

In principle, it is possible to carry out the cooling in the form of air cooling or liquid cooling. In the air cooling, the internal combustion engine is provided with a fan, wherein the heat dissipation takes place by means of guided over the surface of the cylinder head air flows.

By contrast, the liquid cooling requires the equipment of the internal combustion engine or the cylinder head with a coolant jacket ie the arrangement of the coolant through the cylinder head leading coolant channels, which causes a complex structure of the cylinder head construction. In this case, the mechanically and thermally highly stressed cylinder head is weakened by the introduction of the coolant channels on the one hand in its strength. On the other hand, the heat must not be directed to the cylinder head surface as in the air cooling, to be dissipated. The heat is already in the Inside the cylinder head to the coolant, usually mixed with additives added water. The coolant is thereby 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 cylinder head and removed from the coolant in a heat exchanger again.

Due to the significantly higher heat capacity of liquids much larger amounts of heat can be dissipated with a liquid cooling, which is why in a cylinder head of the present type, a liquid cooling is used d. H. in the cylinder head, a coolant jacket is integrated.

For example, a cylinder head with integrated exhaust manifold and liquid cooling reveals EP 1 722 090 A2 , this European patent application is based on the object to provide a compact cylinder head and not a cylinder head with the most efficient cooling possible.

So proves the cooling of the in the EP 1 722 090 A2 described cylinder head in practice also as inadequate, in particular in the area in which the exhaust pipes merge to the overall exhaust line, a thermal overload is to be feared, which can be felt, for example in the form of material melting.

To prevent this, is in an internal combustion engine, with a cylinder head according to the EP 1 722 090 A2 is equipped, always a enrichment (λ <1) made when high exhaust gas temperatures is expected. In this case, more fuel is injected than can be burned at all with the amount of air provided, wherein the additional fuel is also heated and evaporated, so that the temperature of the combustion gases decreases. However, this procedure is considered to be disadvantageous from an energetic point of view, in particular with regard to the fuel consumption of the internal combustion engine, and with regard to the pollutant emissions. In particular, the necessary enrichment does not always allow the internal combustion engine to be operated in the manner required, for example, for a proposed exhaust aftertreatment system.

Taking into account that there has been a shift towards small, supercharged engines and continue to do so, it is apparent that in practice an efficient one can be used Liquid cooling is of ever greater relevance, because the thermal load is even greater with supercharged engines compared to naturally aspirated engines.

Against the background of the above, it is an object of the present invention to provide a cylinder head according to the preamble of claim 1 d. H. provide the generic type, the liquid cooling is optimized and reliably prevents thermal overload of the cylinder head.

Another object of the present invention is to provide a method of operating an internal combustion engine with a cylinder head of the above type and with at least three cylinders.

• mindestens zwei Zylinder in der Art konfiguriert sind, dass sie zwei Gruppen mit jeweils mindestens einem Zylinder bilden, und
• die Abgasleitungen der Zylinder jeder Zylindergruppe unter Ausbildung eines integrierten Abgaskrümmers innerhalb des Zylinderkopfes jeweils zu einer Gesamtabgasleitung zusammenführen,
  und der dadurch gekennzeichnet ist, dass
• der Kühlmittelmantel sich auch zwischen den beiden Gesamtabgasleitungen erstreckt.

The first sub-task is solved by a cylinder head, which is connectable to a cylinder block at a mounting end, with an integrated at least partially in the cylinder head coolant jacket and at least two cylinders, each cylinder has at least one outlet opening for discharging the exhaust gases from the cylinder and connected to each outlet opening an exhaust pipe, and in which

• at least two cylinders are configured to form two groups each having at least one cylinder, and
• combine the exhaust gas lines of the cylinders of each cylinder group to form an integrated exhaust gas manifold within the cylinder head, in each case to form an overall exhaust gas line,
  and which is characterized in that
• the coolant jacket also extends between the two total exhaust pipes.

Embodiments in which the cylinder head has at least three cylinders are advantageous.

The merging of the exhaust gas lines from at least two cylinders to two total exhaust gas lines makes it possible inter alia to configure the cylinders in a suitable manner ie to group or separate from each other - for example, in such a way that the dynamic wave processes in the exhaust pipes of a cylinder group as little as possible disadvantageous influence. It should be on the one hand in the Do not weaken exhaust pipes spreading pressure waves. On the other hand, the cylinders of a cylinder group should preferably have the greatest possible offset with regard to their work processes, so that the cylinders combined in a cylinder group do not adversely influence one another when changing the charge, ie hinder them.

If at the beginning of the charge cycle, an exhaust port is opened by operating an exhaust valve, the combustion gases flow due to the prevailing at the end of the combustion in the cylinder high pressure levels and the associated high pressure difference between the combustion chamber and exhaust d. H. Exhaust pipe at high speed through the exhaust port in the exhaust pipe. This pressure-driven flow process is accompanied by a high pressure spike, also referred to as preload output, propagating along the exhaust pipes at the speed of sound.

With regard to the change of charge, it is advantageous to group the cylinders in such a way that when the at least one exhaust port of one cylinder of one group opens the exhaust ports of the other cylinders of that group are closed or the exhaust ports of the other cylinders of that group are closed at that time are to which the pressure wave or the Vorlastausstoß the opening cylinder arrives at the outlet port of another cylinder or expected. In this way, a return flow of exhaust gas through the outlet opening into the combustion chamber can be avoided.

The grouping of the cylinder also provides more freedom in determining the timing of the valves of a cylinder, as may adversely affecting cylinders can be separated from each other in a suitable manner, namely preferably in such a way that the cylinder of a cylinder group as large as possible offset in terms of their work processes respectively. Thus, in principle, the opening times of the valves, in particular the exhaust valves, be extended or the closing time of the exhaust valves are delayed, without fear that the charge cycle of a cylinder, in particular the Vorlastausstoß a cylinder, for a backflow of exhaust gas through the Outlet opening of another cylinder in the combustion chamber ensures. Investigations have shown that it is possible to exert considerable influence on the efficiency and pollutant emissions, in particular the carbon dioxide emissions (CO ₂ ), via the valve timing.

According to the invention, the exhaust gas lines of the cylinders of each cylinder group are brought together to form an integrated exhaust manifold within the cylinder head to form an overall exhaust gas line.

As has already been discussed above, it is always desirable to arrange the turbine of an exhaust gas turbocharger as close as possible to the outlet of the internal combustion engine and to make the paths of the hot exhaust gases to the various exhaust aftertreatment systems as short as possible. To realize this, the most extensive integration of the exhaust pipes in the cylinder head - as in the inventive cylinder head - expedient.

The length of the exhaust pipes is reduced by integration into the cylinder head. On the one hand, the line volume d. H. reduces the exhaust volume of the exhaust pipes upstream of a possibly provided turbine, so that the response of a turbine arranged downstream of the manifold is improved. On the other hand, the shortened exhaust pipes also lead to a lower thermal inertia of the exhaust system upstream of the turbine, so that the temperature of the exhaust gases is increased at the turbine inlet, which is why the enthalpy of the exhaust gases at the inlet of the turbine is higher. Optionally provided exhaust aftertreatment systems achieve a required minimum operating temperature faster.

As shorten the line lengths of the individual exhaust pipes by integration into the cylinder head, in principle, the risk that the cylinder impede each other in the charge cycle or adversely affect the dynamic wave processes in the exhaust pipes of the cylinder, which should actually be avoided.

In this respect, the grouping of the cylinders is particularly advantageous in connection with the inventive integration of the exhaust pipes into the cylinder head, since in this way the exhaust gas flows can be separated from each other at least up to the total exhaust gas lines. The applied in the cylinder head according to the invention combination of cylinder grouping and integrated into the cylinder head Exhaust pipes thus results in the interaction of these two measures to a synergy effect that goes beyond the benefits of each individual measure for themselves.

The integration of the exhaust pipes according to the invention also allows the densest possible packaging of the drive unit.

According to the invention, the coolant jacket also extends between the two total exhaust gas lines. This includes in particular embodiments in which the coolant jacket an imaginary set around the two exhaust pipes total envelope d. H. Envelope passes through d. H. cuts.

In the area in which exhaust pipes - possibly as partial exhaust gas lines - merge to form an overall exhaust gas line and hot exhaust gas - possibly several cylinders is collected, the cylinder head is thermally particularly high load. This has several reasons.

On the one hand, larger quantities of exhaust gas pass through the two collection points and the two total exhaust gas lines, whereas a single exhaust gas line, which adjoins the outlet opening of a cylinder, is acted upon only by the exhaust gas or a part of the exhaust gas of a cylinder. Ie. the absolute amount of exhaust gas that can give off heat to the cylinder head is the largest here.

On the other hand, the collection points and the total exhaust gas lines are almost continuously exposed to hot exhaust gases, whereas an exhaust pipe of a cylinder d only during the charge cycle of the respective cylinder. H. in a four-stroke internal combustion engine is once flowed through within two crankshaft revolutions of hot exhaust gas.

In addition, it should be noted that in the inflow area of an overall exhaust line, ie in the area of a collection point, the exhaust gas flows of the individual exhaust pipes must be more or less deflected in order to bring the exhaust pipes together to form an overall exhaust line. The individual exhaust gas flows therefore have in this area - at least partially - a speed component, the is perpendicular to the walls of the exhaust pipe, whereby the heat transfer by convection and thus the thermal load of the cylinder head is additionally increased.

For the reasons mentioned, it is therefore advantageous to cool the cylinder head in the immediate vicinity of the entire exhaust gas lines or to equip it with liquid cooling, ie to arrange the coolant jacket at least partially between the two total exhaust gas lines.

On an enrichment of the fuel-air mixture - with the aim of lowering the exhaust gas temperature - can thus be largely eliminated or completely, depending in each case on the number of cylinders, the specific design of the coolant jacket and the like. This proves to be particularly advantageous in terms of fuel consumption and the emission behavior of the internal combustion engine. In addition, there are more freedom in the control of the internal combustion engine, since a possible enrichment to lower the exhaust gas temperature or to protect the cylinder head from thermal overload in the context of engine control no longer needs to be considered.

The cylinder head according to the invention is particularly suitable for supercharged internal combustion engines that require efficient and optimized cooling due to higher exhaust gas temperatures.

Thus, the first of the invention underlying subtask is solved, namely a cylinder head according to the preamble of claim 1 d. H. provide the generic type, the liquid cooling is optimized and reliably prevents thermal overload of the cylinder head.

An internal combustion engine can also have two cylinder heads according to the invention, for example, if the cylinders are arranged distributed on two cylinder banks. Embodiments are also feasible in which the exhaust pipes of all the cylinders of a cylinder head are not combined into two exhaust pipes, but only some of the cylinders arranged in the cylinder head are grouped in the manner according to the invention.

But are particularly advantageous embodiments in which the exhaust pipes of all cylinders of the cylinder head are combined within the cylinder head to two total exhaust pipes.

Further advantageous embodiments of the cylinder head according to the invention are described in connection with the subclaims.

In a cylinder head having at least three cylinders arranged in series, embodiments are advantageous in which the first cylinder group comprises the outer cylinder and the second cylinder group comprises the at least one inner cylinder.

This embodiment shows that a cylinder group according to the invention can also comprise only one cylinder, for example the second cylinder group the inner cylinder of a three-cylinder in-line engine.

The grouping of the three cylinders according to the embodiment in question ensures a symmetrical arrangement of the exhaust pipes in the cylinder head. The firing order of the three cylinders, usually 1 - 2 - 3, is of subordinate importance in view of their configuration here, since completely independent of the configuration of the cylinder combined in a cylinder group two cylinders always both a short firing distance of 240 ° KW and have a long firing interval of 480 ° CA

In a cylinder head with four cylinders arranged in series, embodiments are advantageous in which the first cylinder group comprises the two outer cylinders and the second cylinder group the two inner cylinders, wherein the exhaust pipes of the two outer cylinders of the first cylinder group to form a first integrated exhaust manifold within the Cylinder head to a first overall exhaust line and the exhaust pipes of the two inner cylinder of the second cylinder group within the cylinder head merge to form a second integrated exhaust manifold to a second total exhaust line.

This configuration of the cylinder takes into account the fact that the cylinders of a four-cylinder in-line engine are usually ignited in the order 1 - 3 - 4 - 2, wherein the cylinders beginning with an outer cylinder are numbered consecutively. The proposed grouping of the cylinders ensures that the two cylinders of both the first and the second cylinder group have a firing interval of 360 ° CA. The two cylinders of each cylinder group thus have the largest possible offset in terms of their work processes.

Advantageous embodiments of the cylinder head, in which the two total exhaust gas lines of the two cylinder groups and the integrated exhaust manifold along the longitudinal axis of the cylinder head are arranged offset.

The offset allows a compact design of the cylinder head and at the same time ensures a sufficiently large distance of the total exhaust gas lines from each other. In this way remains - despite the compact design - enough space between the exhaust pipes total compared to embodiments in which the total exhaust gas lines along the longitudinal axis d. H. with view in the direction of the cylinder head longitudinal axis have no offset. This facilitates the arrangement of coolant channels in the cylinder head, in particular between the two total exhaust gas lines.

Embodiments of the cylinder head in which the total exhaust gas line of the second integrated exhaust manifold of the second cylinder group is arranged on the side of the first integrated exhaust manifold of the first cylinder group facing away from the mounting end side are advantageous. According to this embodiment, the exhaust manifolds of the cylinder groups are at least partially superimposed.

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

As already mentioned above, it is a primary goal during the expulsion of the exhaust gases in the context of the charge exchange to release the largest possible flow cross sections as quickly as possible to ensure effective discharge of the exhaust gases, which is why the provision of more than one outlet port per cylinder is advantageous.

Embodiments in which cylinder groups with at least two cylinders initially combine the exhaust lines of the at least two outlet openings of each cylinder into a partial exhaust line belonging to the cylinder are advantageous before these partial exhaust lines merge to form the overall exhaust line of this cylinder group. The total travel distance of all exhaust pipes is thereby - further - shortened and the exhaust gas volume of the manifolds reduced.

The gradual merging of the exhaust pipes to an overall exhaust line also contributes to a more compact d. H. less voluminous design of the cylinder head and thus in particular to a weight reduction and a more effective packaging in the engine compartment.

Embodiments of the cylinder head in which the coolant jacket has a lower coolant jacket, which is arranged between the exhaust pipes and the mounting end side of the cylinder head, and an upper coolant jacket, which is arranged on the side of the exhaust pipes opposite the lower coolant jacket, are advantageous. In this context, also partial exhaust gas lines or total exhaust gas lines are referred to as exhaust pipe and not exclusively exhaust pipes that connect to the outlet port of a cylinder.

Embodiments of the cylinder head in which the lower coolant jacket has at least one inlet opening via which coolant can be supplied and the upper coolant jacket has at least one outlet opening via which the coolant can be discharged are advantageous.

Embodiments of the cylinder head are particularly advantageous in which at least one connection between the lower coolant jacket and the upper coolant jacket, which serves for the passage of coolant, is provided at a distance from the two exhaust manifolds on the side facing away from the at least two cylinders. The at least one connection lies outside the integrated exhaust manifold and in the outer wall of the cylinder head, from which the total exhaust gas lines emerge.

The present embodiment of the cylinder head has at least one connection in the outer wall of the cylinder head, can flow through the coolant from the lower coolant jacket in the upper coolant jacket and / or vice versa.

The connection is an opening or flow channel which connects the lower coolant jacket to the upper coolant jacket and through which a coolant flows.

On the one hand, cooling basically also takes place in the region of the outer wall of the cylinder head. On the other hand, the conventional longitudinal flow of the coolant i. the coolant flow in the direction of the longitudinal axis of the cylinder head is supplemented by a coolant transverse flow which runs transversely to the longitudinal flow and preferably approximately in the direction of the cylinder longitudinal axes. The coolant flow passed through the at least one connection contributes significantly to the heat dissipation. In particular, a suitable dimensioning of the cross section of the at least one connection can specifically influence the flow velocity of the coolant in the connection and thus the heat dissipation in the region of this at least one connection.

Particularly advantageous embodiments of the cylinder head, in which the lower and the upper coolant jacket are not connected to each other over the entire area of the outer wall, but also the at least one connection extends only over a portion of the outer wall in particular. As a result, the flow velocity in the at least one connection can be increased, which increases the heat transfer by convection. This also offers advantages in terms of the mechanical strength of the cylinder head.

The cooling of the cylinder head can additionally and advantageously be improved by generating a pressure gradient between the upper and lower coolant jacket, which in turn increases the speed in the at least one connection, which leads to increased heat transfer due to convection.

Embodiments of the cylinder head in which the at least one connection is arranged adjacent to the region in which exhaust pipes lead to one are advantageous Merge the entire exhaust gas line. As already stated, the cylinder head is subject to particularly high thermal loads in this area, which is why cooling of this area is particularly advantageous.

Embodiments of the cylinder head in which the at least one connection is completely integrated in the outer wall are advantageous. This embodiment is different from, for example, designs of the cylinder head in which an opening is provided in the outer wall, which serves to supply or discharge coolant into and out of the upper and lower coolant jacket. Such an opening is not a connection in the present sense.

In the process, the at least one connection can in the meantime be open to the outside via an access opening in the course of the production of the head, for example for removing a sand core. However, the finished cylinder head has then according to the present embodiment at least one fully integrated in the outer wall connection, including a possibly provided access to the connection is to close.

In principle, embodiments of the cylinder head are also feasible, in which a coolant supply or coolant removal takes place in the region of the at least one connection, for which purpose a channel branches off from the at least one connection which emerges from the outer wall.

Embodiments of the cylinder head in which the distance between the at least one connection and an overall exhaust line is smaller than the diameter, preferably smaller than half the diameter of a cylinder, are advantageous, the distance being from the path between the outer wall of the overall exhaust line and the outer wall the connection results.

Embodiments of the cylinder head in which at least two connections are provided, which are arranged on opposite sides of the two exhaust gas lines, are advantageous. A symmetrical arrangement of the at least two connections in the region of the outer wall takes into account the fact that the system of exhaust pipes integrated in the cylinder head preferably also symmetrically is trained. The mutually corresponding formation of the exhaust system and cooling thus also ensures a symmetrical temperature distribution in the cylinder head.

Embodiments of the cylinder head in which the at least two connections are connected to one another via a coolant jacket region which extends between the two overall exhaust gas lines are advantageous.

Embodiments of the cylinder head are advantageous in which at least one additional connection between the lower coolant jacket and the upper coolant jacket, which serves to pass coolant, is provided at a distance from the exhaust pipes on the side of an exhaust manifold facing the at least two cylinders.

Advantageous embodiments of the cylinder head, in which the two total exhaust gas lines are connected to a twin-flow turbine, wherein in each case an entire exhaust gas line is connected to an inlet channel of the turbine.

In the present case, a double-flow turbine is used to charge the internal combustion engine d. H. The turbine of the turbocharger used has an inlet area with two inlet channels. If the exhaust pipes are grouped in such a way that the high pressures, in particular the Vorlastausstöße can be obtained, a double-flow turbine is particularly suitable for a burst charge, which also high turbine pressure ratios can be achieved at low speeds.

The two total exhaust pipes are connected separately to each other with an inlet channel. The merging of the two exhaust gas flows conducted in the total exhaust gas lines is optionally carried out downstream of the turbine, but in this case not upstream of the turbine. An entire exhaust gas line already opens into an inlet channel of the turbine when the exhaust gas flow guided in the overall exhaust gas line essentially-preferably completely-arrives in the inlet channel assigned to the overall exhaust gas line.

Embodiments in which guide vanes for influencing the flow direction are arranged in the inlet region of the twin-flow turbine are advantageous. In contrast to The vanes of the revolving impeller do not rotate vanes with a shaft of a turbine.

If a turbine has a fixed invariable geometry, the vanes are not only stationary but also completely immovable in the entrance area, i.e., they are stationary. rigidly fixed. If, on the other hand, a turbine with variable geometry is used, the guide vanes are indeed arranged stationary, but not completely immobile, but rotatable about their axis, so that the flow of the blades can be influenced.

Embodiments in which the twin-flow turbine is an axial turbine are advantageous.

In an axial turbine, the flow of the impeller blades takes place substantially axially, wherein "substantially axially" means that the velocity component in the axial direction is greater than the radial velocity component. The velocity vector of the flow in the region of the impeller preferably runs parallel to the shaft or axis of the exhaust gas turbocharger, if the flow is exactly axial.

The use of an axial turbine makes the d in radial turbines mandatory. H. inherently unavoidable radial supply of the exhaust gas by means of spiral or screw housing dispensable, whereby the pressure loss in the exhaust gas can be reduced and the exhaust gas enthalpy can be increased at the entrance to the turbine. The supply of the exhaust gas by means of spiral or screw housing requires the multiple deflection of the exhaust gas or the exhaust gas flows with large changes in direction, each change in direction causes a pressure drop in the exhaust gas flow, which is why the exhaust gas at the turbine less energy can be withdrawn.

Embodiments of the cylinder head in which each overall exhaust gas line is connected to a turbine of an exhaust gas turbocharger are advantageous. In the present case, two parallel turbines or exhaust gas turbochargers are used to charge the internal combustion engine. This is a measure for improving the torque characteristic of a supercharged internal combustion engine.

The second object of the invention, namely to provide a method for operating an internal combustion engine with a cylinder head of the aforementioned type and at least three cylinders, is achieved by a method which is characterized in that the at least three cylinders are operated in the manner that the cylinders of a cylinder group have the largest possible offset with regard to the work processes.

What has been said for the cylinder head according to the invention also applies to the method according to the invention, which is why reference is made to the statements already made above.

In a cylinder head with four cylinders arranged in series, in which the exhaust lines of the two outer cylinders of a first cylinder group merge into a first overall exhaust line and the exhaust lines of the two inner cylinders of a second cylinder group to form a second overall exhaust line, method variants are advantageous, which are characterized that combustion is initiated alternately in an outer cylinder of the first cylinder group and an inner cylinder of the second cylinder group.

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.

Fig. 1

in einer perspektivischen Darstellung den Sandkern der im Zylinderkopf gemäß einer ersten Ausführungsform integrierten Abgasleitungen,

Fig. 2

den in Figur 1 dargestellten Sandkern in einer Seitenansicht,

Fig. 3

in einer perspektivischen den Sandkern des im Zylinderkopf gemäß einer ersten Ausführungsform integrierten Kühlmittelmantels,

Fig. 4

den in Figur 3 dargestellten Sandkern in einer Seitenansicht mit Blick in Richtung der Längsachse des Zylinderkopfes,

Fig. 5

Teile des in Figur 3 dargestellten Sandkerns in einer Draufsicht, und

Fig. 6

den in Figur 3 dargestellten Sandkern in einer Seitenansicht mit Blick senkrecht zur Längsachse des Zylinderkopfes.

In the following the invention is based on an embodiment according to the FIGS. 1 to 6 described in more detail. Hereby shows:

Fig. 1

in a perspective view of the sand core of the cylinder head according to a first embodiment integrated exhaust pipes,

Fig. 2

the in FIG. 1 shown sand core in a side view,

Fig. 3

in a perspective view of the sand core of the coolant jacket integrated in the cylinder head according to a first embodiment,

Fig. 4

the in FIG. 3 shown sand core in a side view looking in the direction of the longitudinal axis of the cylinder head,

Fig. 5

Parts of in FIG. 3 shown sand core in a plan view, and

Fig. 6

the in FIG. 3 shown sand core in a side view with a view perpendicular to the longitudinal axis of the cylinder head.

FIG. 1 shows a perspective view of the sand core 1 for forming the integrated cylinder head according to a first embodiment, exhaust pipes 4a, 4b, 5, 6 ', 6 ". FIG. 1 Thus, the system of integrated in the cylinder head exhaust pipes 4a, 4b, 5, 6 ', 6 ", which is why the reference numerals for the exhaust pipes 4a, 4b, 5, 6', 6" are registered.

At the in FIG. 1 The sand core 1 or exhaust system shown is the exhaust pipes 4a, 4b, 5, 6 ', 6 "of a cylinder head of a four-cylinder in-line engine, in which the cylinders are arranged along the longitudinal axis of the cylinder head two outlet openings 3a, 3b equipped, with an exhaust pipe 4a, 4b connected to each outlet opening 3a, 3b.

The four cylinders are configured to form two groups of two cylinders each. The first cylinder group comprises the two outer cylinders and the second cylinder group the two inner cylinders, wherein the exhaust pipes 4a, 4b of the two outer cylinders of the first cylinder group to form a first integrated exhaust manifold 2 'within the cylinder head to a first total exhaust pipe 6' and the exhaust pipes 4a, 4b of the two inner cylinders of the second cylinder group within the cylinder head to form a second integrated exhaust manifold 2 "to a second total exhaust line 6" merge.

The exhaust pipes 4a, 4b of each cylinder initially lead to a partial exhaust gas line 5 belonging to the cylinder, before the partial exhaust gas lines 5 of the cylinders of a cylinder group subsequently d. H. downstream to an overall exhaust line 6 ', 6 "merge.

At the in FIG. 1 shown exhaust system, the two total exhaust pipes 6 ', 6 "of the integrated exhaust manifold 2', 2" offset along the longitudinal axis of the cylinder head arranged. The total exhaust line 6 "of the second integrated exhaust manifold 2" of the second cylinder group lies on the side facing away from the mounting end side of the first integrated exhaust manifold 2 '.

FIG. 2 shows the in FIG. 1 shown sand core 1 in a side view with a view in the direction of the longitudinal axis of the cylinder head. For the same components, the same reference numerals as in FIG. 1 For that reason, reference is otherwise made to FIG. 1 ,

How out FIG. 2 it can be seen, the total exhaust line 6 "of the second integrated exhaust manifold 2" of the second cylinder group lies on the side facing away from the mounting end side of the first integrated exhaust manifold 2 'ie above the first exhaust manifold 2'.

FIG. 3 shows a perspective view of the sand core 7 for forming the cylinder head according to a first embodiment integrated coolant jacket 8.

The coolant jacket 8 comprises a lower coolant jacket 8a, which is arranged between the exhaust pipes and a mounting end face of the cylinder head, not shown, an upper coolant jacket 8b, which is arranged on the opposite side of the lower coolant jacket 8a exhaust pipes 5, and a central coolant jacket 8c , which is arranged between the total exhaust gas lines 6 ', 6 ", kinks inwards and thus follows the course of the second integrated exhaust manifold (see also FIG. 2 ).

In the outer wall of the cylinder head, from which the total exhaust gas lines 6 ', 6 "emerge, two connections 9 are provided, which connect the lower coolant jacket 8a to the upper coolant jacket 8b and serve for the passage of coolant Total exhaust pipes 6 ', 6 "arranged and even connected to each other via the middle coolant jacket 8c.

The lower and upper coolant jacket 8a, 8b are not connected to one another over the entire area of the outer wall, but only over a partial area of the outer wall, namely adjacent to the overall exhaust gas lines 6 ', 6 " two compounds 9 are thus arranged adjacent to the area in which the cylinder head is thermally stressed particularly high.

The in the upper, lower and middle coolant jacket 8a, 8b, 8c adjusting longitudinal flows - in the direction of the longitudinal axis of the cylinder head - are supplemented by the two transverse flows in the compounds 9 (see also FIG. 5 ).

To remove the sand core 7 after casting the cylinder head, two accesses 10 are provided in the region of the connections 9, which are closed after removal of the sand core 7, so that the connections 9 are completely integrated in the outer wall.

FIG. 4 shows the in FIG. 3 shown sand core 7 in a side view with a view in the direction of the longitudinal axis of the cylinder head. For the same components, the same reference numerals as in FIG. 3 For that reason, reference is otherwise made to FIG. 3 ,

How out FIG. 4 can be seen, an additional connection 11 between the lower coolant jacket 8a and the upper coolant jacket 8b is provided on the side facing the cylinders of the first exhaust manifold, which serves for the passage of coolant.

In addition, an additional access 12 for removing the sand core 7 and for processing the additional connection 11 is provided, which is closed again in the finished cylinder head.

Evident is also a coolant inlet 13 for supplying coolant into the lower coolant jacket 8a and a coolant outlet 14 for discharging coolant from the upper coolant jacket 8b.

FIG. 5 shows in a plan view the parts of in FIG. 3 shown sand core, which serve to form the lower and middle coolant jacket 8a, 8c, with a view in the direction of the cylinder longitudinal axes. For the same components, the same reference numerals as in FIG. 3 For that reason, reference is otherwise made to FIG. 3 ,

The flow directions of the coolant when flowing through the coolant jackets 8a, 8c are shown as arrows. The coolant flows in a fan-shaped manner from the coolant inlets of the lower coolant jacket 8 a into the middle coolant jacket 8 c, namely through the two connections 9 in the outer wall and the additional connection 11.

FIG. 6 shows the in FIG. 3 shown sand core 7 in a side view with a view perpendicular to the longitudinal axis of the cylinder head. For the same components, the same reference numerals as in Figures 3 and 4 Otherwise, reference is made to these figures.

The coolant flows from the outward coolant inlets 13 of the lower coolant jacket 8a along the longitudinal axis of the cylinder head to the connections 9 and vertically through these connections 9 into the middle and lower coolant jacket 8a, 8c.

The upper coolant jacket 8b also has two external coolant inlets 15, wherein the coolant leaves the coolant jacket 8 via the coolant outlet 14 or is removed.

reference numeral

1

sand core

2 '

first integrated exhaust manifold

2 '

second integrated exhaust manifold

3a

first outlet opening

3b

second outlet opening

4a

first exhaust pipe

4b

second exhaust pipe

5

Part exhaust pipe

6 '

Total exhaust pipe

6 "

Total exhaust pipe

7

sand core

8th

Coolant jacket

8a

lower coolant jacket

8b

Upper coolant jacket

8c

medium coolant jacket

9

connection

10

Access

11

additional connection

12

additional access

13

Coolant inlet

14

Coolant outlet

15

Coolant inlet

KW

crank angle

Claims (14)

Cylinder head, which is connectable to a cylinder block at a mounting end face, with an at least partially integrated in the cylinder head coolant jacket (8) and at least two cylinders, each cylinder at least one outlet opening (3a, 3b) for discharging the exhaust gases from the cylinder and at each outlet opening (3a, 3b) an exhaust pipe (4a, 4b) connects, and in the - At least two cylinders are configured in such a way that they form two groups, each with at least one cylinder, and - The exhaust pipes (4a, 4b) of the cylinders of each cylinder group together to form an integrated exhaust manifold (2 ', 2 ") within the cylinder head in each case to an overall exhaust line (6', 6 ''),
characterized in that - The coolant jacket (8) also extends between the two total exhaust pipes (6 ', 6''). Cylinder head according to claim 1, having at least three cylinders arranged in series,
characterized in that
the first cylinder group comprises the outer cylinders and the second cylinder group comprises the at least one inner cylinder. Cylinder head according to claim 2 with four cylinders arranged in series,
characterized in that
the first cylinder group comprises the two outer cylinders and the second cylinder group comprises the two inner cylinders, the exhaust pipes (4a, 4b) of the two outer cylinders of the first cylinder group forming a first integrated exhaust manifold (2 ') within the cylinder head to a first exhaust line ( 6 ') and the exhaust pipes (4a, 4b) of the two inner cylinders of the second cylinder group within the cylinder head to form a second integrated exhaust manifold (2 ") to a second total exhaust line (6") merge. Cylinder head according to one of the preceding claims,
characterized in that
the two total exhaust pipes (6 ', 6 ") of the two cylinder groups are arranged offset along the longitudinal axis of the cylinder head. Cylinder head according to one of the preceding claims,
characterized in that
the total exhaust line (6 '') of the second integrated exhaust manifold (2 '') of the second cylinder group is disposed on the side facing away from the mounting end side of the first integrated exhaust manifold (2 ') of the first cylinder group. Cylinder head according to one of the preceding claims,
characterized in that
each cylinder has at least two exhaust ports (3a, 3b) for exhausting the exhaust gases from the cylinder. Cylinder head according to claim 6,
characterized in that
in the case of cylinder groups having at least two cylinders, first the exhaust gas lines (4a, 4b) of the at least two outlet openings (3a, 3b) of each cylinder merge to form a partial exhaust gas line (5) belonging to the cylinder before these partial exhaust gas lines (5) are connected to the total exhaust gas line (6 ', 6 "). ) merge the cylinder group. Cylinder head according to one of the preceding claims,
characterized in that
the coolant jacket (8) has a lower coolant jacket (8a) which is arranged between the exhaust gas lines (4a, 4b, 5, 6 ', 6 ") and the mounting end face of the cylinder head, and an upper coolant jacket (8b) which is mounted on the the lower coolant jacket (8a) opposite side of the exhaust pipes (4a, 4b, 5, 6 ', 6'') is arranged. Cylinder head according to one of the preceding claims,
characterized in that
spaced from the exhaust pipes (4a, 4b, 5, 6 ', 6 ") on the at least two cylinders side facing away from the two exhaust manifolds (2', 2") at least one connection (9) between the lower coolant jacket (8a) and upper coolant jacket (8b) is provided, which serves for the passage of coolant. Cylinder head according to claim 9,
characterized in that
at least two connections (9) are provided, which are arranged on opposite sides of the two total exhaust gas lines (6 ', 6 "). Cylinder head according to claim 10,
characterized in that
the at least two connections (9) are interconnected via a coolant jacket region which extends between the two total exhaust gas lines (6 ', 6''). Cylinder head according to one of the preceding claims,
characterized in that
spaced to the exhaust pipes (4a, 4b, 5, 6 ', 6 ") on the at least two cylinders side facing an exhaust manifold (2', 2") at least one additional connection (11) between the lower coolant jacket (8a) and upper coolant jacket (8b) is provided, which serves for the passage of coolant. Method for operating an internal combustion engine having a cylinder head according to one of the preceding claims with at least three cylinders,
characterized in that
the at least three cylinders are operated in such a way that the cylinders of a cylinder group have the greatest possible offset with regard to the working processes. Method according to claim 13 for operating an internal combustion engine with a cylinder head according to one of claims 3 to 12,
characterized in that
alternately at an outer cylinder of the first cylinder group and an inner cylinder of the second cylinder group, the combustion is initiated.

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