DE102017200001A1 - Internal combustion engine with cylinder head and method for producing a cylinder head of such an internal combustion engine - Google Patents

Abstract

The invention relates to an internal combustion engine having at least one cylinder head comprising at least one cylinder, wherein each cylinder has at least one inlet opening, wherein an intake duct for supplying air via intake connects to each inlet opening, each cylinder has at least one outlet opening, wherein at each exhaust port connects an exhaust pipe (1) for discharging exhaust gas via Abgasabführsystem, and- at least one exhaust pipe (1) has a cross section (1a) which changes in the flow direction.Es an internal combustion engine of the type mentioned will be provided, wherein the Abgasabführsystem This is achieved by an internal combustion engine, which is characterized in that the cross-section (1a) at least in places has a trapezoidal basic shape.

Description

• - jeder Zylinder mindestens eine Einlassöffnung aufweist, wobei sich an jede Einlassöffnung eine Ansaugleitung zum Zuführen von Luft via Ansaugsystem anschließt,
• - jeder Zylinder mindestens eine Auslassöffnung aufweist, wobei sich an jede Auslassöffnung eine Abgasleitung zum Abführen von Abgas via Abgasabführsystem anschließt, und
• - mindestens eine Abgasleitung einen Querschnitt aufweist, der sich in Strömungsrichtung ändert.

The invention relates to an internal combustion engine having at least one cylinder head comprising at least one cylinder, in which

• each cylinder has at least one inlet opening, wherein a suction line for supplying air via the suction system adjoins each inlet opening,
• each cylinder has at least one outlet opening, wherein an exhaust pipe for discharging exhaust gas via exhaust gas discharge system adjoins each outlet opening, and
• - At least one exhaust pipe has a cross section which changes in the flow direction.

Furthermore, the invention relates to a method for producing a cylinder head of such an internal combustion engine.

An internal combustion engine of the type mentioned is used for example as a motor vehicle drive. In the context of the present invention, the term internal combustion engine includes diesel engines and gasoline engines, but also hybrid internal combustion engines, which use a hybrid combustion process, and hybrid drives, which in addition to the internal combustion engine comprise an electric motor which can be electrically connected to the internal combustion engine, which receives power from the internal combustion engine or as switchable auxiliary drive additionally delivers power.

Internal combustion engines have at least one cylinder head, which is used to form the at least one cylinder, d. H. the at least one combustion chamber, is connected to a cylinder block, wherein bores for receiving connecting elements are provided for connecting in the cylinder head and in the cylinder block.

The cylinder block has for receiving the piston or the cylinder tubes on a corresponding number of cylinder bores in which the pistons are guided axially movable. The cylinder head usually serves to accommodate the valve trains. To control the charge cycle, an internal combustion engine requires controls and actuators to operate the controls. As part of the charge cycle, the combustion gases are expelled via the at least one outlet opening and the filling of the combustion chamber via the at least one inlet opening of the cylinder. For controlling the charge cycle, four-stroke engines use almost exclusively globe valves as control members which perform an oscillating stroke movement during operation of the internal combustion engine and in this way release and close the inlet opening or outlet opening. The required for the movement of a valve valve actuating mechanism including the valve itself is referred to as a valve train. A valve actuating device regularly comprises a camshaft, wherein overhead camshafts, d. H. Camshafts, which lie above the parting line between the cylinder head and the cylinder block, are mounted on the cylinder head.

It is the object of a valve drive to release the at least one inlet opening or the at least one outlet opening of a cylinder in good time, with a quick release of the largest possible flow cross sections is sought to keep the throttling losses in the incoming and outflowing gas flows low and the best possible filling of the cylinder or an effective, d. H. ensure complete expulsion of the combustion gases.

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

In the course of the charge cycle, the pressures in the cylinder and in the exhaust line are the same, so that the combustion gases are primarily not evacuated pressure driven, but are ejected as a result of the stroke of the piston.

The pressure losses along the exhaust pipe, d. H. in the direction of flow, take - as already mentioned - with increasing distance due to friction, which is always striving to minimize these pressure losses. On the one hand, in order to ensure effective discharge of the exhaust gas without backflow, and on the other hand, in order to provide a possibly high-energy exhaust gas available to a turbine of an exhaust-gas turbocharger optionally provided downstream in the exhaust-gas removal system.

When charged by turbocharger supercharged internal combustion engines is therefore also sought to arrange the turbine as close 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.

To achieve the above objects, the exhaust pipes of an internal combustion engine are preferably combined to form an integrated exhaust manifold within the cylinder head, i. H. the exhaust manifold is fully integrated into the cylinder head. Such a cylinder head is also characterized by a very compact design, which allows a dense packaging of the entire drive unit. In addition, it is possible to participate in an optionally provided in the cylinder head liquid cooling, in the way that the manifold does not have to be made of thermally highly durable and thus costly materials.

The use of a cylinder head with integrated manifold also leads to a smaller number of components and consequently to a reduction in costs, in particular the installation and deployment costs.

The cylinder head of a modern internal combustion engine is usually subject to higher thermal loads and therefore also places increased demands on the cooling, in particular if the cylinder head is equipped with an integrated exhaust manifold and / or the internal combustion engine is a supercharged internal combustion engine.

If the internal combustion engine has liquid cooling, a plurality of coolant channels or at least one coolant jacket are generally formed in the cylinder head, which or which guide the coolant through the cylinder head, resulting in a more complex cylinder head structure.

The above statements make it clear that the cylinder head of an internal combustion engine is a thermally and mechanically highly loaded component. In spark-ignited internal combustion engines, moreover, the required ignition device, in direct-injection internal combustion engines beyond the injection device can be arranged in the cylinder head.

In view of the foregoing, it is an object of the present invention to provide an internal combustion engine according to the preamble of claim 1, wherein the exhaust gas discharge system is optimized in terms of discharging the exhaust gas.

Another object of the present invention is to provide a method for manufacturing a cylinder head of such an internal combustion engine.

• - jeder Zylinder mindestens eine Einlassöffnung aufweist, wobei sich an jede Einlassöffnung eine Ansaugleitung zum Zuführen von Luft via Ansaugsystem anschließt,
• - jeder Zylinder mindestens eine Auslassöffnung aufweist, wobei sich an jede Auslassöffnung eine Abgasleitung zum Abführen von Abgas via Abgasabführsystem anschließt, und
• - mindestens eine Abgasleitung einen Querschnitt aufweist, der sich in Strömungsrichtung ändert, und die dadurch gekennzeichnet ist, dass
• - der Querschnitt zumindest stellenweise eine trapezförmige Grundform aufweist.

The first sub-task is solved by an internal combustion engine with at least one cylinder head comprising at least one cylinder in which

• each cylinder has at least one inlet opening, wherein a suction line for supplying air via the suction system adjoins each inlet opening,
• each cylinder has at least one outlet opening, wherein an exhaust pipe for discharging exhaust gas via exhaust gas discharge system adjoins each outlet opening, and
• - At least one exhaust pipe has a cross section which changes in the flow direction, and which is characterized in that
• - The cross section at least in places has a trapezoidal basic shape.

According to the invention, the cross-section, at least in places, has an essentially trapezoidal basic shape. At least one exhaust pipe of the Abgasabführsystems changes in the flow direction, d. H. along the exhaust pipe and along the central streamline, their cross-section such that the cross-section is substantially trapezoidal at least at one location in the basic shape.

The trapezoidal cross section according to the invention has proven to be suitable for forming an advantageous exhaust gas removal system for the effective removal of the exhaust gas.

It has been shown that a trapezoidal cross section minimizes or reduces the pressure losses due to friction. On the one hand, an effective removal of the exhaust gas without backflow can be realized. On the other hand, a turbine of an exhaust-gas turbocharger, which is optionally provided downstream in the exhaust-gas removal system, can be provided with an exhaust gas which is as energy-rich as possible.

With the internal combustion engine according to the invention, the first object of the invention is achieved, namely an internal combustion engine according to the preamble of claim 1 is provided, wherein the Abgasabführsystem is optimized with respect to the discharge of the exhaust gas.

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

Embodiments of the internal combustion engine in which the cross section has at least one rounded corner are advantageous. It has proven to be advantageous in terms of flow, if the edge bordering the cross section has no sharp-edged corners, but rather curves.

For this reason, embodiments of the internal combustion engine are advantageous in which an edge bounding the cross section is curved. Then the cross section has no corners.

Embodiments of the internal combustion engine may be advantageous in which an edge bounding the cross-section extends at least in sections in a wave-like manner, with both a regular and an irregular wavy course being able to be effective.

Embodiments of the internal combustion engine may be advantageous in which an edge delimiting the trapezoidal cross-section extends undulating on opposite sides of the cross-section.

Embodiments of the internal combustion engine in which the cross section is arranged within the at least one cylinder head are advantageous.

Embodiments of the internal combustion engine may also be advantageous in which the cross section is arranged outside the at least one cylinder head.

The exhaust pipes of an internal combustion engine can merge to form an integrated exhaust manifold within the cylinder head or to form an external exhaust manifold outside of the cylinder head.

If the exhaust pipes lead together to form an integrated exhaust manifold inside the cylinder head, the cross section according to the invention is necessarily arranged inside the at least one cylinder head.

In internal combustion engines having at least two exhaust pipes, embodiments are advantageous in which the at least two exhaust gas lines merge within the at least one cylinder head to form an integrated exhaust manifold to form an overall exhaust gas line.

In internal combustion engines having at least two exhaust pipes, however, embodiments may also be advantageous in which the at least two exhaust gas lines outside the at least one cylinder head merge to form an exhaust gas line to form an external exhaust manifold.

Advantageous embodiments of the internal combustion engine, in which each cylinder is equipped with an injection device for the direct injection of fuel into the cylinder.

Direct injection is a concept for dethrottling a gasoline engine, d. H. a spark-ignited internal combustion engine, in which the load control takes place by means of quantity control. The injection of fuel directly into the combustion chamber of the cylinder is to be regarded as a suitable measure to noticeably reduce fuel consumption even in gasoline engines. The Entdrosselung the internal combustion engine is realized that within certain limits, a quality control is used. With the direct injection of the fuel into the combustion chamber can be realized in particular a stratified combustion chamber charge, which can significantly contribute to the dethrottling of the ottomotor work process, since the internal combustion engine with the help of the stratified operation can be emaciated very far, which is particularly in part-load operation, d. H. In the lower and middle load range, when only small amounts of fuel are to be injected, it offers thermodynamic benefits.

In this context, embodiments of the internal combustion engine in which the injection device is arranged in each case in the cylinder head are advantageous.

Advantageous embodiments of the internal combustion engine, in which a charge is provided.

Embodiments of the internal combustion engine in which at least one exhaust-gas turbocharger is provided, which comprises a turbine arranged in the exhaust-gas removal system and a compressor arranged in the intake system, are advantageous.

The charge is a suitable means to increase the capacity of an internal combustion engine with unchanged displacement or to reduce the displacement at the same power. In any case leads the charge to an increase in space performance and a lower power mass. If the cubic capacity is reduced, the load spectrum can be shifted to higher loads at the same vehicle boundary conditions, where the specific fuel consumption is lower. The charging of an internal combustion engine thus supports the efforts to minimize fuel consumption, ie to improve the efficiency of the internal combustion engine.

By means of a suitable transmission design, a so-called downspeeding can additionally be realized, as a result of which a lower specific fuel consumption is likewise achieved. Downspeeding exploits the fact that the specific fuel consumption at low speeds is regularly lower, especially at higher loads.

With targeted design of the charge also benefits in the exhaust emissions can be achieved. Thus, by means of suitable charging, for example in the diesel engine, the nitrogen oxide emissions can be reduced without sacrificing efficiency. At the same time, the hydrocarbon emissions can be favorably influenced. The emissions of carbon dioxide, which correlate directly with fuel consumption, also decrease with decreasing fuel consumption.

Frequently, an exhaust gas turbocharger is used for charging, in which a compressor and a turbine are arranged on the same shaft. The hot exhaust stream is supplied to the turbine and relaxes with energy release in the turbine, causing the shaft to rotate. The energy emitted by the exhaust gas flow to the turbine and finally to the shaft is used to drive the compressor, which is also arranged on the shaft. The compressor conveys and compresses the charge air supplied to it, whereby a charging of the cylinder is achieved. Advantageously, a charge air cooler is provided downstream of the compressor in the intake system, with which the compressed charge air is cooled before entering the cylinder. The radiator lowers the temperature and thus increases the density of the charge air, so that the cooler to a better filling of the cylinder, d. H. contributes to a larger air mass. There is a compaction by cooling.

The advantage of an exhaust gas turbocharger in comparison to a supercharger which is driven by means of an auxiliary drive is that an exhaust gas turbocharger uses the exhaust gas energy of the hot exhaust gases, while a supercharger obtains the energy required for its drive directly or indirectly from the internal combustion engine and thus, at least as long the drive energy does not come from an energy recovery, adversely affects the efficiency, d. H. decreases.

If it is not an electric machine, d. H. is electrically driven supercharger is regularly a mechanical or kinematic connection for power transmission between the charger and the internal combustion engine is required, which also adversely affects or determines the packaging in the engine compartment.

The advantage of a supercharger over an exhaust gas turbocharger, in turn, is that the supercharger can always generate and provide the required boost pressure, regardless of the operating state of the internal combustion engine. This is especially true for a loader that is electrically driven by electric motor and therefore independent of the speed of the crankshaft.

Therefore, embodiments of the internal combustion engine may also be advantageous in which at least one supercharger drivable by means of an auxiliary drive is provided.

• - jeder Zylinder mindestens zwei Einlassöffnungen aufweist, wobei sich an jede Einlassöffnung eine Ansaugleitung zum Zuführen von Luft via Ansaugsystem anschließt, und/oder
• - jeder Zylinder mindestens zwei Auslassöffnungen aufweist, wobei sich an jede Auslassöffnung eine Abgasleitung zum Abführen von Abgas via Abgasabführsystem anschließt.

Embodiments of the internal combustion engine are advantageous in which

• - Each cylinder has at least two inlet openings, wherein an intake duct for supplying air via the intake system connects to each inlet opening, and / or
• - Each cylinder has at least two outlet openings, wherein an exhaust pipe for discharging exhaust gas via Abgasabführsystem connects to each outlet opening.

This embodiment assists the valve trains to quickly release the largest possible flow cross sections for the gases when changing the charge.

Embodiments of the internal combustion engine in which the cross section is rotated relative to a longitudinal axis of the at least one cylinder by an angle α are advantageous. In this case, for α, preferably: α ≥ 10 °.

The second sub-task, namely to show a method for producing a cylinder head of an internal combustion engine of a type described above, is achieved by a method in which the cylinder head is cast.

What has already been said for the internal combustion engine according to the invention also applies to the method according to the invention, which is why at this point in general reference is made to the statements made with regard to the internal combustion engine.

Also advantageous are methods in which the cylinder head is manufactured with an additive manufacturing process in which the cylinder head is built up in layers.

Embodiments of the method in which the cylinder head is produced at least by means of 3D printing are also advantageous.

• 1a schematisch und in einer dreidimensionalen Darstellung ein Teilstück einer Abgasleitung einer ersten Ausführungsform der Brennkraftmaschine,
• 1b schematisch und in einer dreidimensionalen Darstellung ausgewählte Querschnitte der in 1a dargestellten Abgasleitung,
• 2 einen Querschnitt einer Abgasleitung einer zweiten Ausführungsform der Brennkraftmaschine, und
• 3 einen Querschnitt einer Abgasleitung einer dritten Ausführungsform der Brennkraftmaschine.

In the following the invention with reference to three embodiments and according to the figures 1a, 1b, 2 and 3 will be described in more detail. Hereby shows:

• 1a schematically and in a three-dimensional representation of a portion of an exhaust pipe of a first embodiment of the internal combustion engine,
• 1b schematically and in a three-dimensional representation selected cross sections of in 1a illustrated exhaust pipe,
• 2 a cross section of an exhaust pipe of a second embodiment of the internal combustion engine, and
• 3 a cross section of an exhaust pipe of a third embodiment of the internal combustion engine.

1a shows schematically and in a three-dimensional representation of a portion of an exhaust pipe 1 a first embodiment of the internal combustion engine.

The exhaust pipe 1 Connects to the outlet opening of a cylinder of the internal combustion engine and serves for the discharge of exhaust gas from the cylinder via Abgasabführsystem. The flow direction of the exhaust gas is with an arrow at the inlet into the exhaust pipe 1 , the outlet opening of the cylinder, marked.

Starting from the circular outlet opening of the cylinder changes the exhaust pipe 1 in the flow direction of their cross section 1a , where the cross section 1a at least at one point of the exhaust pipe 1 has a trapezoidal basic shape.

1b shows schematically and in a three-dimensional representation selected cross-sections 1a the in 1a illustrated exhaust pipe 1 , in the 1a indicated by black lines.

The essentially trapezoidal cross section 1a is from a border 1b limited, the curvy and sections wavy. The edge 1b has rounded corners.

2 shows a cross section 1a an exhaust pipe 1 a second embodiment of the internal combustion engine. The cross section 1a has a trapezoidal basic shape or in the present case is trapezoidal, wherein the edge 1b has rounded corners.

3 shows a cross section 1a an exhaust pipe 1 a third embodiment of the internal combustion engine. The cross section 1a has a trapezoidal basic shape. The rim 1b has rounded corners and is wavy on opposite sides of the cross-section 1a.

LIST OF REFERENCE NUMBERS

1

exhaust pipe

1a

cross-section

1b

edge

Claims (14)

Internal combustion engine having at least one cylinder head comprising at least one cylinder, in which - each cylinder has at least one inlet opening, wherein an intake duct for supplying air via intake connects to each inlet opening, - each cylinder has at least one outlet opening, wherein an exhaust pipe to each outlet opening (1) for discharging exhaust gas via Abgasabführsystem connects, and - at least one exhaust pipe (1) has a cross section (1a) which changes in the flow direction, characterized in that - the cross section (1a) at least in places has a trapezoidal basic shape. Internal combustion engine after Claim 1 , characterized in that the cross section (1a) has at least one rounded corner. Internal combustion engine after Claim 1 or 2 , characterized in that a cross-section (1a) limiting edge (1b) is curved. Internal combustion engine according to one of the preceding claims, characterized in that a cross-section (1a) bounding edge (1b) extends at least partially undulating. Internal combustion engine according to one of the preceding claims, characterized in that a trapezoidal cross section (1a) limiting edge (1b) on opposite sides of the cross section (1a) is wavy. Internal combustion engine according to any one of the preceding claims, characterized in that the cross section (1a) within the at least one cylinder head is arranged. Internal combustion engine according to one of Claims 1 to 5 , characterized in that the cross section (1a) is arranged outside the at least one cylinder head. Internal combustion engine according to one of the preceding claims with at least two exhaust pipes (1), characterized in that the at least two exhaust pipes (1) merge within the at least one cylinder head to form an integrated exhaust manifold to form an overall exhaust gas line. Internal combustion engine according to one of Claims 1 to 7 with at least two exhaust pipes (1), characterized in that the at least two exhaust pipes (1) merge outside of the at least one cylinder head to form an external exhaust manifold to form an overall exhaust gas line. Internal combustion engine according to one of the preceding claims, characterized in that each cylinder is equipped with an injection device for the direct injection of fuel into the cylinder. Internal combustion engine after Claim 10 , characterized in that the injection device is arranged in each case in the cylinder head. Internal combustion engine according to one of the preceding claims, characterized in that at least one exhaust gas turbocharger is provided which comprises a turbine arranged in the exhaust gas discharge system and a compressor arranged in the intake system. Internal combustion engine according to one of the preceding claims, characterized in that the cross section (1a) is rotated relative to a longitudinal axis of the at least one cylinder by an angle α. A method for producing a cylinder head of an internal combustion engine according to any one of the preceding claims, characterized in that the cylinder head is cast.

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