EP1972772B1 - Cylinder head for a fluid-cooled combustion engine - Google Patents

Description

The invention relates to a cylinder head for a liquid-cooled internal combustion engine with the features of the preamble of patent claim 1.

For example, from the British patent application GB 2 175 046 A a liquid-cooled cylinder head for an internal combustion engine is known. In order to obtain smaller casting cores when casting the cylinder head, it is provided that a separate coolant jacket is provided for each combustion chamber. With this first the combustion chamber roof and then the center arranged between the four gas exchange valves injector or the centrally arranged ignition device is cooled.

Next is from the international patent application WO 2005/042955 A2 a liquid-cooled internal combustion engine with a cylinder head known. The cylinder head has two inlet and two outlet channel openings per cylinder, which are arranged substantially symmetrically with respect to at least one transverse plane of the cylinder head. Adjacent to a combustion chamber roof is a first cooling space to which, in turn, a second cooling space partially adjoins, wherein the first and the second cooling space are flow-connected to one another via at least one flow connection per cylinder.

The invention is based on the not yet published German patent application DE 10 2006 036 422 out. In this a liquid-cooled cylinder head for an internal combustion engine is described, with a first and a second, adjacent to each other, partially merging into each other, surrounded by a coolant passage Auslasskanalwandung for two Auslassgaswechselventile. Spaced apart from an inlet-side, formed by the Auslasskanalwandungen gusset region, an at least partially surrounded by a coolant channel dome is arranged. This dome is for a largely centered to the combustion chamber covered by the cylinder head can be arranged engine component such. B. an ignition device and / or a fuel injection device, wherein the coolant channel has a first, substantially centrally disposed between the first and the second Auslasskanalwandung inlet and a second and a third of the first inflow opening in the cylinder head longitudinal direction having spaced inflow opening in a cylinder head separation plane. Starting from the first inflow opening, the coolant channel extends largely over the combustion chamber and between the first and the second outlet duct wall in the direction of the dome. Starting from the second and the third inflow opening, the coolant channel extends largely over the combustion chamber and radially around the first and the second outlet channel wall in the direction of the dome and starting from the dome in the direction of the inlet side of the cylinder head. For better cooling of the dome, a first flow guide rib extending in the direction of the dome is arranged in a gusset region of the coolant channel.

The generic design of the coolant channel in a cylinder head of an internal combustion engine has excellent cooling properties for the Dombereich.

Object of the present invention is to show a measure by which the outlet side of the cylinder head can be even more uniform and thus better cooled.

This object is achieved by the features in the characterizing part of patent claim 1.
Due to the improved cooling on Gaswechselauslassventilsteg the life of the inventively designed cylinder head is increased or it can cost-effective alloys such. B. AISi8 instead of AISi7 be used for the same life. From the improved cooling of the Gaswechselauslassventilsteges also benefits the ignition and / or injection device, so that, for example, igniters avoided or reduced. The coolant flow is deflected by appropriate shaping near the combustion chamber roof in the horizontal direction and diverted in the direction of web between Gaswechseleinlass- and Gaswechselauslassventil. By thus achieved higher flow velocity of the Coolant cooling at the Gaswechseleinlass- and Gaswechselauslassventilsteg where frequent thermo-mechanical fatigue cracks occur improved.

With the embodiment according to claim 2, a further coolant-carrying connection with the crankcase is shown, which uses the vent hole for the crankcase in an advantageous manner as a flow channel for further cooling of the webs between the Gaswechseleinlass- and Gaswechselauslassventile.

Due to the embodiments according to the claims 3 and 4, the gas exchange outlet ducts and the ignition and / or fuel injection device are cooled particularly well.

Fig. 1

zeigt eine Aufsicht auf einen dreidimensional dargestellten Gusskern eines erfindungsgemäß ausgeformten Kühlmittelkanals;

Fig. 2

zeigt eine Aufsicht auf den dreidimensional dargestellten Gusskern des erfindungsgemäß ausgeformten Kühlmittelkanals aus einer anderen Perspektive;

Fig. 3

zeigt ein Diagramm von einer Temperaturverteilung von Gaswechselauslassventilstegen einer 6-Zylinder-Brennkraftmaschine.

In the following the invention with reference to a particularly preferred embodiment in two figures and with the aid of a single diagram is explained in more detail:

Fig. 1

shows a plan view of a three-dimensionally illustrated casting core of an inventively shaped coolant channel;

Fig. 2

shows a plan view of the three-dimensionally illustrated casting core of the invention shaped coolant channel from a different perspective;

Fig. 3

shows a diagram of a temperature distribution of Gaswechselauslassventilstegen a 6-cylinder engine.

Fig. 1 shows the top view of a portion of a three-dimensionally illustrated casting core of an inventively shaped coolant channel 5. The coolant channel 5 is provided for a multi-cylinder series internal combustion engine, but only a portion of the coolant channel 5 is shown for about two and a half cylinders. The multi-cylinder cylinder head has a longitudinal axis LA, which is symbolically represented by an arrow. On one side of the longitudinal axis LA is an inlet side 3 and on the other hand the longitudinal axis LA is an outlet side 1 of the cylinder head.

Each cylinder has in the illustrated embodiment in the inlet side 3, two gas exchange inlet ducts 4, 4 'and in the outlet side 1, two gas exchange outlet ducts 2, 2. Next, the coolant channel 5 for each cylinder two inlet openings 6, 6 ', is promoted by the coolant during operation of the internal combustion engine from a crankcase, not shown in the cylinder head. The flow direction of the coolant is shown schematically by arrows. The inflow openings 6, 6 'are arranged substantially below the gas exchange outlet channels 2, 2. From the inlet openings 6, 6 ', the coolant flows geodetically upwards into the inflow cross section of the coolant channel 5 and further largely horizontally first away from the inlet side 3 and further arcuately back towards the outlet side 1 to merge into a common coolant channel and further into a web area between the gas exchange outlet channels 2, 2 'to open. Proceeding from the web region, the coolant in the coolant channel 5 continues to flow upward geodetically and surrounds the gas exchange outlet channels 2, 2 and a region arranged largely centrically to a cylinder, not shown, in which an ignition and / or a fuel injection unit can be arranged. Starting from this area, the coolant continues to flow in the direction of inlet side 3 of the cylinder head. In order to cool the region of the ignition and / or fuel injection device particularly well, the coolant channel 5 has on both sides of the gas exchange outlet channels 2, 2 'a further connection 7, 7 to the crankcase, which can simultaneously serve as a vent hole for the crankcase. Between two cylinders in each case a core support 8, 8 'is arranged for fixing the position of the casting core during the casting process of the cylinder head.

In the present embodiment, the coolant jacket 5 is provided for a 6-cylinder internal combustion engine. However, any other internal combustion engine with any number of cylinders can be equipped with the inventively designed coolant channel 5.

In Fig. 2 in which the same reference numbers apply to the same components as in Fig. 1 , is also a plan view of the three-dimensional dargstellten casting core of the coolant channel 5 shown, but with improved view of the inlet openings 6, 6 '. The flow direction of the coolant is again shown schematically by arrows. Out Fig. 2 It can be seen how the coolant, which enters the cylinder head through the inlet openings 6, 6 ', first flows "M-shaped" away from the inlet side 3 of the cylinder head and then back to the inlet side 3. In the middle, in the web region between gas exchange outlet channels 2, 2, the coolant channel 5 is brought together again to form a single coolant channel 5. After this channel merge, the coolant is then conveyed geodetically upwards, where it flows around the gas exchange outlet channels 2, 2 'and the region of the ignition and / or fuel injection device.

Fig. 3 shows a diagram of a temperature distribution of Gaswechselauslassventilstegtemperaturen for a 6-cylinder internal combustion engine. The temperatures are derived from a simulation validated by measurements. The gas exchange outlet valve temperature is plotted in degrees Celsius above the Y axis. Six individual measuring points in the cylinder head are shown above the X axis.

Two graphs 9 and 10 show the temperature profile over the length of the cylinder head, for known from the prior art cooling concepts. In contrast, a third graph 11 shows the temperature profile for a cylinder head with a coolant channel 5 formed according to the invention. It can clearly be seen that the temperature difference from the first to the sixth cylinder with the inventive design of the coolant channel 5 is only about 10 ° C., while the temperature difference for the cylinder conventional cooling concepts, graphs 9 and 10, up to 25 ° C.

In summary, it can be said that the proposal according to the invention eliminates the abovementioned disadvantages without sustainably influencing the pressure loss in the cooling system.

• Der Kühlmittelübertritt vom Kurbelgehäuse zum Zylinderkopf erfolgt je Zylinder zweimal auf der Auslassseite 1, jeweils über vorzugsweise nierenförmige Querschnitte in der Brennraumplatte des Zylinderkopfes. Die nierenförmigen Einströmöffnungen 6, 6' sind durch eine Kühlmittelmantelunterbrechung jeweils zweigeteilt, wobei die beiden äußeren "Füße" des Kühlmittelübertrittes durch eine nicht dargestellte Zylinderkopfdichtung abgedeckt werden, damit das Kühlmittel nicht hauptsächlich in die äußeren Bereiche des Zylinders strömt. Die notwendige Stabilität des Kühlmittelmantelkerns für den Gießprozess wird dadurch erreicht, dass die Kühlmittelübertritte unterhalb der Zylinderkopfdichtfläche durch eine nicht dargestellte Kernleiste miteinander verbunden werden. Das Kühlmittel tritt durch die mittleren Querschnitte ein und wird unmittelbar in Richtung eines Abgasflansches und mit etwa 5° bis 40° in Richtung Zylindermitte umgelenkt. Beide Kühlmittelteilströme vereinigen sich dann in der Zylindermitte mittels einer steifigkeitsförderlichen Leitrippe zu einem Kanal, der nun direkt auf den Gaswechselauslassventilsteg zielt. In der Draufsicht betrachtet hat diese Kühlmittelführung die Form eines "M', weshalb vom sog. "M-Port' gesprochen wird.

A targeted flow of the critical zones in the cylinder head and thus the cooling of the outlet side Gaswechselauslassventilsteges and a horizontal, direct flow of the combustion chamber roof is achieved by the following features:

• The coolant transfer from the crankcase to the cylinder head takes place per cylinder twice on the outlet side 1, in each case via preferably kidney-shaped cross sections in the combustion chamber plate of the cylinder head. The kidney-shaped inflow openings 6, 6 'are divided into two by a coolant jacket interruption, wherein the two outer "feet" of the coolant passage are covered by a cylinder head gasket, not shown, so that the coolant does not flow mainly into the outer regions of the cylinder. The necessary stability of the coolant jacket core for the casting process is achieved in that the coolant passages below the cylinder head sealing surface are connected to each other by a core strip, not shown. The coolant enters through the central cross sections and is deflected directly in the direction of an exhaust flange and at approximately 5 ° to 40 ° in the direction of the cylinder center. Both coolant sub-streams unite then in the center of the cylinder by means of a stiffness-promoting guide rib to a channel, which now aims directly at the Gaswechselauslassventilsteg. Viewed in plan view, this coolant guide has the shape of an "M", which is why the so-called. "M-port" is spoken.

Although the additional deflection of the coolant flow in the "M port" increases the pressure loss in the cooling system, this is largely compensated for by the fact that, in the case of a coolant channel 5 with "M port", tuning of the cylinder head gasket for uniform coolant distribution over all cylinders is largely dispensed with can.

Due to the additional connection 7, 7 of the coolant channel 5 with the coolant channel in the crankcase, a so-called. Kurbelgehäusezwickelentlüftung is achieved. The coolant flow through the vent hole is deflected in the coolant channel 5 by appropriate shaping near the combustion chamber roof in the horizontal direction and diverted in the direction of a bridge between Gaswechseleinlass- and Gaswechselauslassventil. As a result of the resulting higher flow velocity of the coolant, the cooling at the Gaswechseleinlass- and Gaswechselauslassventilsteg, where frequently thermo-mechanical fatigue cracks occur, improved.

The improved cooling in the Gaswechselauslass- as well as the Gaswechseleinlassventilsteg (by the flow deflection at the other connection 7, 7 ', the crankcase ventilation bore) increases the life, or cheaper alloys (eg., AlSi8 instead of AISi7) can be used for the same life become. From the improved cooling of Gaswechselauslassventilsteges also benefits the ignition, so that pre-ignition can be avoided or reduced.

Based on Fig. 3 It has been shown that the cooling due to the clean coolant flow is so good that it is necessary to adjust the cylinder head gasket can be largely dispensed with the uniform distribution of the coolant to the cylinder. The "M-port" thus achieves a very great insensitivity of the gas exchange outlet valve stem temperatures compared to the uniform distribution both in the case of long cylinder heads, such as in a row 6-cylinder cylinder head and with respect to the injection point of the coolant in the crankcase As a positive side effect, the underside of the gas exchange outlet duct 2, 2 'is cooled by the "M port", as a result of which the thermal distortion of the entire cylinder head is reduced.

LIST OF REFERENCE NUMBERS

1.

outlet

2, 2 '

Gaswechselauslasskanal

Third

inlet side

4, 4 '

Gas exchange inlet channel

5th

Coolant channel

6, 6 '

inflow

7, 7

connection

8, 8 '

core support

9th

first cooling variant

10th

second cooling variant

11th

Cooling variant according to the invention

Claims (4)

1. A cylinder head for a liquid-cooled internal combustion engine, with two gas-exchange outlet ducts (2, 2') arranged in an outlet side (1) of the cylinder head and two gas-exchange inlet ducts (4, 4') arranged in an inlet side (3) of the cylinder head, which are each arranged along a longitudinal cylinder head axis (LA), and with an ignition and/or fuel-injection device which can be arranged between the gas-exchange ducts (2, 2', 4, 4'), wherein a coolant duct (5) in the cylinder head has two outlet-side coolant inflow openings (6, 6') which are open towards a crankcase arranged geodetically below the cylinder head, which openings are each arranged largely geodetically below a gas-exchange outlet duct (2, 2'), wherein the coolant duct (5) between the gas-exchange outlet ducts (2, 2') extends in the direction of the ignition and/or fuel-injection device and geodetically upwards,
   characterised in that the coolant duct (5) extends starting from the inflow openings (6, 6') on both sides up to a duct height and then in an arc-shape, first away from the inlet side (3) and then towards the inlet side (3) and then into the coolant duct (5) between the gas-exchange outlet ducts (2, 2').
2. A cylinder head according to Claim 1,
   characterised in that the coolant duct (5) in the longitudinal direction of the cylinder head next to at least one gas-exchange outlet duct (2, 2) has at least one further coolant-carrying connection (7, 7') with a coolant duct in the crankcase, and in that geodetically above the connection (7, 7') the coolant duct points in the direction of an area between a gas-exchange inlet duct and a gas-exchange outlet duct.
3. A cylinder head according to Claim 1 or Claim 2,
   characterised in that the coolant duct (5) surrounds the gas-exchange outlet ducts (2, 2) geodetically above its M-shaped inflow region.
4. A cylinder head according to one of Claims 1 to 3,
   characterised in that the coolant duct (5) surrounds the ignition and/or fuel-injection device.

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