EP2003320B1 - Cylinder head for an internal combustion engine - Google Patents

Description

• sich an jede Auslaßöffnung eine Abgasleitung anschließt,
• die Abgasleitungen der mindestens zwei Zylinder innerhalb des Zylinderkopfes zu einer Gesamtabgasleitung zusammenführen, und
• der Kühlmittelmantel einen unteren Kühlmittelmantel, der zwischen den Abgasleitungen und der Montage-Stirnseite des Zylinderkopfes angeordnet ist, und einen oberen Kühlmittelmantel, der auf der dem unteren Kühlmittelmantel gegenüberliegenden Seite der Abgasleitungen angeordnet ist, aufweist.

The invention relates to a 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 for an internal combustion engine having at least two cylinders, wherein each cylinder has at least one outlet opening for discharging the exhaust gases from the cylinder, in which

• adjoining each outlet opening an exhaust pipe,
• merge the exhaust gas lines of the at least two cylinders within the cylinder head into an overall exhaust gas line, and
• the coolant jacket has a lower coolant jacket, which is arranged between the exhaust pipes and the mounting end face of the cylinder head, and an upper coolant jacket which is arranged on the side of the exhaust pipes opposite the lower coolant jacket.

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 guided axially movably in the cylinder tubes and, together with the cylinder tubes and the cylinder head, form 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. To control the charge cycle, an internal combustion engine requires controls and actuators to operate the 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. For controlling the charge cycle, four-stroke engines use almost exclusively globe valves as control members, which perform an oscillating lifting movement during operation of the internal combustion engine and in this way release and close the inlet and outlet openings. The required for the movement of the valves valve actuating mechanism including the valves themselves is referred to as a valve train.

A valve actuating device comprises a camshaft on which a plurality of cams is arranged. Basically, a distinction is made between an underlying camshaft and an overhead camshaft. In this case, reference is made to the parting line between the cylinder head and cylinder block. If the camshaft is above this parting line, it is an overhead camshaft, otherwise a camshaft underneath.

Overhead camshafts are also mounted in the cylinder head, wherein a valve train with overhead camshaft as a further valve train component has a rocker arm, a rocker arm or a plunger.

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 according to the state of Technology at least partially integrated in the cylinder head. The exhaust pipes of the outlet openings of a single cylinder are usually - within the cylinder head - merged into a cylinder associated partial exhaust gas line, these partial exhaust gas lines are then brought together outside of the cylinder by means of a so-called (exhaust) manifold; often to a single overall exhaust line.

Downstream of the 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 endeavors to arrange the exhaust gas turbocharger or the closest possible to the outlet of the internal combustion engine in order to make optimum use of the exhaust enthalpy of the hot exhaust gases in this way and to ensure a rapid response of the turbocharger. 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, therefore, it is basically 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 exhaust gas turbocharger, 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 manifold is integrated with the cylinder head. Such a cylinder head, in which connects to each outlet opening an exhaust pipe and merge the exhaust gas lines of the cylinder within the cylinder head to form an overall exhaust gas line, is also the subject of the present invention.

However, such a trained cylinder head is thermally loaded higher than a conventional cylinder head, which is equipped with an external manifold, and therefore has increased cooling requirements.

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.

On the other hand, the liquid cooling requires the equipment of the internal combustion engine or the cylinder head with a coolant jacket d. H. 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 interior of 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 compared to air can be dissipated with the liquid cooling much larger amounts of heat than is possible with an air cooling.

For the reasons mentioned, a coolant jacket is integrated in the cylinder head according to the prior art in a cylinder head of the present type, wherein the coolant jacket has a lower coolant jacket, which is arranged between the exhaust pipes and the mounting end face of the cylinder head, and an upper coolant jacket, the the side opposite the lower coolant jacket side of the exhaust pipes is arranged comprises.

A cylinder head according to the preamble of claim 1 ie the generic type discloses the US 2005/0087154 A1 , Another cylinder head reveals the 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 as insufficient, in particular, in the area in which the exhaust pipes merge to the entire exhaust line, a thermal overload is to be feared, which may manifest itself, for example in the form of material.

In order to prevent this, in an internal combustion engine which is equipped with such a cylinder head, enrichment (λ <1) is always carried out when high exhaust gas temperatures are to be 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 disadvantageous in terms of energy, in particular with regard to the fuel consumption of the internal combustion engine and with regard to the pollutant emissions. In particular, 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 trend towards small, supercharged engines and continue to do so, it will be appreciated that efficient liquid cooling is becoming increasingly important in practice because the thermal load is significant on highly supercharged engines as compared to conventional internal combustion engines greater.

Against the background of the above, it is the object of the present invention, a cylinder head according to the preamble of claim 1 d. H. provide the generic type, which is equipped with a coolant jacket, with which the known prior art disadvantages are overcome and ensures an optimized cooling of the cylinder head, without a thermal overload of the cylinder head is to be feared.

This object is achieved by a cylinder head according to claim 1. The cylinder head according to the invention has - in contrast to that in the EP 1 722 090 A2 described cylinder head - via at least one compound that is at least one breakthrough in the outer wall of the cylinder head, through which or the coolant from the lower coolant jacket can flow into the upper coolant jacket and vice versa. On the one hand, in principle cooling takes place in the region of the outer wall of the cylinder head, to which, according to the state of the art, consciously - for the realization of a compact design - is omitted. On the other hand, the conventional longitudinal flow of the coolant, ie 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 cylinder head according to the invention is thermally higher loadable than the known from the prior art cylinder head. On a enrichment of the fuel-air mixture - with the aim of lowering the exhaust gas temperature - can thus largely or completely be dispensed with, which in each case depends on the internal combustion engine, the number of cylinders, the specific training of at least one compound 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 object underlying the invention is achieved, namely to provide a liquid-cooled cylinder head, which has an optimized cooling.

Embodiments of the cylinder head in which the lower and the upper coolant jacket are not connected to one another over the entire area of the outer wall are advantageous, but the at least one connection only extends over a partial area of the outer wall. 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.

Embodiments of the cylinder head in which the at least one connection is arranged adjacent to the region in which the exhaust gas lines merge to form the overall exhaust gas line are advantageous.

In the area in which the exhaust gas lines lead into a common exhaust gas line and the hot exhaust gas of all cylinders of the internal combustion engine is collected, the cylinder head is subject to particularly high thermal loads. This has several reasons.

On the one hand, the entire exhaust gas of the internal combustion engine passes through this collection point in the exhaust system, whereas a single exhaust line, which is then acted upon by the exhaust port of a cylinder, only with the exhaust gas or a portion 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 mouth region of the exhaust pipes in the entire exhaust line is continuously exposed to hot exhaust gases, whereas the exhaust pipes of a cylinder - for example, in a four-stroke internal combustion engine - only during the change of charge of the respective cylinder d. H. is once passed through within two crankshaft revolutions of hot exhaust gas.

In addition, it should be noted that in the inflow area of the entire exhaust line, ie in the region of the collection point, the exhaust gas flows of the individual exhaust pipes must be more or less deflected in order to merge the exhaust pipes to a common total exhaust line can. The individual exhaust gas flows therefore have in this area - at least partially - a speed component which is perpendicular to the walls of the exhaust pipe, whereby the heat transfer by convection and consequently the thermal load of the cylinder head is additionally increased. For the reasons mentioned above, the embodiment of the cylinder head in question, in which the at least one connection in the vicinity of the mouth region is arranged in the overall exhaust gas line, ie in the vicinity of the collection point of the exhaust gas lines, is advantageous. In the cylinder head according to the invention, the distance between the at least one connection and the total exhaust gas line is less than half the diameter of a cylinder, wherein the distance from the distance between the outer wall of the entire exhaust line and the outer wall of the compound results.

Embodiments of the cylinder head in which at least two connections are provided, which are arranged on opposite sides of the overall exhaust gas line, 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 integrated system in the cylinder head system of exhaust pipes is usually symmetrical. The mutually corresponding formation of the exhaust system and cooling thus also ensures a symmetrical temperature distribution in the cylinder head.

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 in the introduction to the introduction, it is a primary goal during discharge of the exhaust gases as part 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 opening is advantageous.

Embodiments of the cylinder head in which at least one cylinder is provided between the exhaust pipes of at least one cylinder-at a distance from these exhaust pipes-at least one connection between the lower coolant jacket and the upper coolant jacket are advantageous. In this way, a cooling in the immediate vicinity of the outlet openings can be realized, which is advantageous if it is taken into account that the exhaust gases have the highest temperature when leaving the cylinder.

Furthermore, embodiments of the cylinder head are advantageous in which first the exhaust gas lines of the at least two outlet openings of each cylinder merge to form a partial exhaust gas line belonging to the cylinder before these partial exhaust gas lines of the at least two cylinders merge to form the total exhaust gas line.

This embodiment of the integrated system of exhaust pipes is similar to the formation of a conventional exhaust manifold, the procedure is similar. The total travel distance of all exhaust pipes is thereby shortened.

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

Embodiments of the cylinder head in which at least one connection between the lower coolant jacket and the upper coolant jacket is provided between the partial exhaust gas lines of at least two adjacent cylinders-at a distance from these partial exhaust gas lines-are advantageous.

In the - usually fork-shaped - merging of the partial exhaust gas lines, the wall thickness of the partial exhaust gas lines tapers apart wall, so that this wall, especially in the area in which the merger actually takes place, is thermally highly loaded. Providing a connection d. H. a cooling channel for the purpose of heat dissipation is therefore advantageous. The same considerations and relationships also apply to the previously described embodiment of the cylinder head, in which between the exhaust pipes of at least one cylinder at least one connection between the lower coolant jacket and the upper coolant jacket is provided.

But can also be advantageous embodiments of the cylinder head, in which each cylinder has an outlet opening for discharging the exhaust gases from the cylinder.

Embodiments of the cylinder head are advantageous in which at least one connection between the lower coolant jacket and the upper coolant jacket is provided between the exhaust pipes of at least two adjacent cylinders spaced from these exhaust pipes.

Fig. 1

in einer leicht angestellten Draufsicht den Sandkern der in einer ersten Ausführungsform des Zylinderkopfes integrierten Abgasleitungen,

Fig. 2

in einer perspektivischen Darstellung den in Figur 1 dargestellten Sandkern zusammen mit dem Kühlmittelmantel der ersten Ausführungsform des Zylinderkopfes, und

Fig. 3

in einer perspektivischen Darstellung die erste Ausführungsform des Zylinderkopfes.

In the following the invention with reference to an embodiment according to the FIGS. 1 to 3 described in more detail. Hereby shows:

Fig. 1

in a lightly employed plan view, the sand core of the integrated in a first embodiment of the cylinder head exhaust pipes,

Fig. 2

in a perspective view the in FIG. 1 illustrated sand core together with the coolant jacket of the first embodiment of the cylinder head, and

Fig. 3

in a perspective view of the first embodiment of the cylinder head.

FIG. 1 shows in a slightly salaried plan view of the sand core 13 of the integrated in a first embodiment of the cylinder head exhaust pipes 4a, 4b, 5, 6, so that FIG. 1 In principle, the system of integrated in the cylinder head exhaust pipes 4a, 4b, 5, 6 illustrates, which is why the reference numerals for the exhaust pipes 4a, 4b, 5, 6 are registered.

At the in FIG. 1 illustrated sand core 13 and exhaust system is the exhaust pipes 4a, 4b, 5, 6 of a cylinder head of a four-cylinder internal combustion engine. Each of the four cylinders is provided with two outlet openings 3a, 3b, with an exhaust pipe 4a, 4b connected to each outlet opening 3a, 3b.

The exhaust pipes 4a, 4b of each cylinder lead to a cylinder associated with the partial exhaust gas line 5, wherein the partial exhaust gas lines 5 then d. H. downstream merge together to form a common total exhaust line 6.

Between the partial exhaust gas lines 5 of two adjacent cylinders, it is optionally possible to provide connections 15 between the lower coolant jacket and the upper coolant jacket (shown as dot-dashed circles) spaced from these partial exhaust gas lines 5.

The optional connections 15 assist the cooling of the highly thermally loaded collection point 8, at which the exhaust gas streams of all cylinders merge d. H. to be collected. The entire exhaust gas of the internal combustion engine passes through this collection point 8 d. H. the mouth region 8 of the partial exhaust gas lines 5, where the partial exhaust gas lines 5 open into the total exhaust gas line 6.

In an outer wall of the cylinder head, from which the entire exhaust line 6 exits, two connections 7 are provided between the lower coolant jacket and the upper coolant jacket, which in turn serve the passage of coolant (shown as dash-dotted ellipses).

The compounds 7 are adjacent to the total exhaust line 6 d. H. to the region 8, in which the exhaust pipes 4a, 4b, 5 merge to the total exhaust gas line 6.

FIG. 2 shows in a perspective view the in FIG. 1 illustrated sand core 13 together with the coolant jacket 2 of the first embodiment of the cylinder head.

The coolant jacket 2 comprises a lower coolant jacket 2 a, which between the exhaust pipes 5 and a non-illustrated mounting end face of the cylinder head (see FIG. 3 ), and an upper coolant jacket 2b, which is arranged on the opposite side of the lower coolant jacket 2a of the exhaust pipes 5.

In the outer wall of the cylinder head, from which the entire exhaust gas line 6 exits, two connections 7 are provided between the lower coolant jacket 2a and the upper coolant jacket 2b, which serve for the passage of coolant.

The lower and the upper coolant jacket 2a, 2b 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 line 6.

The two connections 7 are thus arranged adjacent to the region in which the exhaust gas lines 5 merge to form the overall exhaust gas line 6. H. where the cylinder head is subject to high thermal loads.

The entire exhaust gas of the internal combustion engine flows through the collection point, which is continuously charged with hot exhaust gases, whereas the exhaust pipes 5 of a cylinder are only temporarily flowed through by hot exhaust gas. In addition, the exhaust gas flows are deflected in the collection area.

The two connections 7 permit cooling also in the area of the outer wall of the cylinder head, wherein the longitudinal flows adjusting in the upper and lower coolant jacket 2a, 2b are supplemented by two coolant flows, which run transversely to the longitudinal flows, in the direction of the longitudinal axis of the cylinder head. The flows of the coolant are indicated by arrows.

To remove the sand core 13 after casting of the cylinder head, two accesses 12 are provided in the region of the total exhaust gas line 6 or the connections 7, which are closed after removal of the sand core 13.

It can also be seen that each cylinder has not only two outlet openings 3, 3b, but also two inlet openings 11a, 11b.

FIG. 3 shows in a perspective view of the first embodiment of the cylinder head 1 and that from below, ie with a view of the mounting end face 9 and the inlet openings 11a, 11b of the cylinder.

Evident is the outwardly curved outer wall 10, in the center of the outlet of the entire exhaust line 6 is arranged from the cylinder head 1, wherein a flange 14 is provided, on which an exhaust pipe for discharging the exhaust gases from the cylinder head 1 is attached.

reference numeral

1

cylinder head

2

Coolant jacket

2a

lower coolant jacket

2 B

Upper coolant jacket

3a

first outlet opening

3b

second outlet opening

4a

first exhaust pipe

4b

second exhaust pipe

5

Part exhaust pipe

6

Total exhaust pipe

7

connection

8th

Mouth area, collection point

9

Mounting-end side

10

outer wall

11a

first inlet opening

11b

second inlet opening

12

Access

13

sand core

14

flange

15

optional connection

Claims (8)

1. Cylinder head (1) which, at an assembly end-side (9), can be connected to a cylinder block, having a coolant jacket (2), which is at least partially integrated in the cylinder head (1), for an internal combustion engine having at least two cylinders, in which each cylinder has at least one outlet opening (3a, 3b) for discharging the exhaust gases out of the cylinder, with

   - an exhaust-gas line (4a, 4b) adjoining each outlet opening (3a, 3b),

   - the exhaust-gas lines (4a, 4b) of the at least two cylinders merging within the cylinder head (1) to form a combined exhaust-gas line (6),

   - the coolant jacket (2) having a lower coolant jacket (2a), which is arranged between the exhaust-gas lines (4a, 4b, 5, 6) and the assembly end-side (9) of the cylinder head (1), and an upper coolant jacket (2b), which is arranged on that side of the exhaust-gas lines (4a, 4b, 5, 6) which is situated opposite the lower coolant jacket (2a), and

   - at a distance from the exhaust-gas lines (4a, 4b, 5, 6), at least one connection (7) between the lower coolant jacket (2a) and the upper coolant jacket (2b) being provided in an outer wall (10), from which the combined exhaust-gas line (6) emerges, of the cylinder head (1), which connection (7) serves for the passage of coolant,

   characterized in that

   - the at least one connection (7) is arranged adjacent to the region (8) in which the exhaust-gas lines (4a, 4b, 5) merge to form the combined exhaust-gas line (6), wherein the spacing between the at least one connection (7) and the combined exhaust-gas line (6) is less than half of the diameter of a cylinder.
2. Cylinder head (1) according to Claim 1, characterized in that
   at least two connections (7) are provided, which are arranged on opposite sides of the combined exhaust-gas line (6).
3. Cylinder head (1) according to Claim 1 or 2, characterized in that
   each cylinder has at least two outlet openings (3a, 3b) for discharging the exhaust gases out of the cylinder.
4. Cylinder head (1) according to Claim 3, characterized in that
   at least one connection between the lower coolant jacket (2a) and the upper coolant jacket (2b) is provided between the exhaust-gas lines (4a, 4b) of at least one cylinder - at a distance from said exhaust-gas lines (4a, 4b).
5. Cylinder head according to Claim 3 or 4, characterized in that
   the exhaust-gas lines (4a, 4b) of the at least two outlet openings (3a, 3b) of each cylinder firstly merge to form a partial exhaust-gas line (5) which is associated with the cylinder, before said partial exhaust-gas lines (5) of the at least two cylinders merge to form the combined exhaust-gas line (6).
6. Cylinder head (1) according to Claim 5, characterized in that
   at least one connection (15) between the lower coolant jacket (2a) and the upper coolant jacket (2b) is provided between the partial exhaust-gas lines (5) of at least two adjacent cylinders - at a distance from said partial exhaust-gas lines (5).
7. Cylinder head (1) according to Claim 1 or 2, characterized in that
   each cylinder has one outlet opening (3a, 3b) for discharging the exhaust gases out of the cylinder.
8. Cylinder head (1) according to Claim 7, characterized in that
   at least one connection between the lower coolant jacket (2a) and the upper coolant jacket (2b) is provided between the exhaust-gas lines (4a, 4b) of at least two adjacent cylinders - at a distance from said exhaust-gas lines (4a, 4b).

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