Cylinder head with cast cooling water channels as well as method and casting cores for producing same

A cylinder head for a multi-cylinder internal combustion engine with a plurality of cylinder portions, each having gas changing channels, valve guides and bolt holes for one cylinder. The cylinder head is provided with a deck face designed to rest on a cylinder block. A valve drive pan is positioned opposite the deck face. Two longitudinally extending side faces and two end faces form the cylinder head. The cylinder head also has a cast longitudinal cooling water channel which extends along the plurality of cylinder portions. The longitudinal cooling water channel has cooling water entry and cooling water exit apertures designed to be connected to cooling water channels in the cylinder block. At least one cast transverse cooling water channel is provided for ventilating purposes and for discharging vapor bubbles. The transverse cooling water channel extends transversely to the longitudinal direction along the plurality of cylinder portions in an intermediate floor above the longitudinal cooling water channel. The cast transverse cooling water channel, at its one end close to a side face of the cylinder head, is connected to the longitudinal cooling water channel by a transfer aperture. At its other end opposed to the transfer aperture and close to the other side face, the transverse cooling water channel has a discharge member.

BACKGROUND OF THE INVENTION 
The invention relates to a cylinder head casting for a multicylinder 
combustion engine with a plurality of cylinder portions. Each cylinder 
portion includes gas changing channels, valve guides and bolt holes for 
one cylinder. The cylinder head is provided with a deck face designed to 
rest on a cylinder block. A valve drive pan is positioned opposite the 
deck face. The cylinder head has two longitudinally extending side faces 
and two end faces. The cylinder head has a cast longitudinal cooling water 
channel which extends along the plurality of cylinder portions. The 
longitudinal cooling water channel includes cooling water entry apertures 
and cooling water exit apertures designed to be connected to cooling water 
channels in the cylinder block. Furthermore, the invention relates to a 
method of casting such a cylinder head casting and to a casting core 
suitable for carrying out the casting method. 
In the case of engines subject to high loads due to increasing performance 
density, the formation of vapor bubbles constitutes a greater and greater 
problem in the cooling water system. The vapor bubbles must be avoided 
because of the deterioration in heat transfer and the resulting 
impermissible thermal stresses. In modern two valve, three valve, four 
valve or five valve engines, with 2, 3, 4 or 5 valves per cylinder, the 
problem is intensified as the longitudinal cooling water channel has more 
and more branches and clefts. Thus, portions are formed with a reduced 
cooling water flow speed, which encourage the formation of vapor bubbles. 
A cylinder head casting is known from DE 28 39 199 C2. A longitudinal 
cooling water channel extends in the vicinity of a side face on the inlet 
gas channel side. Transverse cooling water channels are provided as bores. 
The bores are connected to niche-like water chambers which can be deformed 
from their cores after casting towards the separating plane between the 
cylinder head and cylinder block. The bores serve to ensure a defined flow 
of cooling water. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide a cylinder head casting 
which comprises means acting against the formation of vapor bubbles. 
Furthermore, it is an object of the invention to provide a suitable method 
of producing such means. 
The inventive cylinder head casting is provided with at least one cast 
transverse cooling water channel. The transverse cooling water channel is 
provided for ventilating purposes and for discharging vapor bubbles. The 
transverse cooling water channel extends transversely to the longitudinal 
direction of the plurality of cylinder portions in an intermediate floor 
above the longitudinal cooling water channel. The cast transverse cooling 
water channel, at its one end is connected to the longitudinal cooling 
water channel by means of a transfer aperture close to a side face of the 
cylinder head. A discharge means is provided at the transverse cooling 
water channels other end opposed to the transfer aperture and close to the 
other side face. 
In an inventive cylinder head casting, at least one transverse cooling 
water channel is arranged halfway along the length of the cylinder head or 
in the rear cylinder head half when viewed in the direction of flow of the 
longitudinal cooling water channel. However, preferably each one of the 
cylinder portions comprises its own transverse cooling water channel. 
Thus, the thermal conditions of the cylinder portions are balanced. 
The transverse cooling water channels make it possible, especially in each 
one of the individual cylinder portions, to discharge any vapor bubbles 
near their place of origin. A partial cooling water flow is returned 
directly to the cylinder block so that larger vapor bubble clusters cannot 
occur in the individual cylinder portions. In a preferred embodiment, each 
transverse cooling water channel is provided with a bent discharge 
portion. The bent discharge portion extends as far as the deck face. In 
this embodiment, the discharge means ends at the deck face so that the 
respective partial cooling water flow can be returned via an inlet in the 
respective counter face of the cylinder block. However, it is also 
possible for the discharge means to end at the side face and for the 
discharge means to return by means of an outer pipe into the cylinder 
block or directly to the radiator. 
According to a preferred embodiment, the longitudinal cooling water 
channel, in the region of each transfer aperture leading to a transverse 
cooling water channel, forms a dome. The dome, a bell-shaped widened 
portion, facilitates the transport of any vapor bubbles even at low flow 
speeds of the partial cooling water flow and with small cross-sections of 
the transverse cooling water channel. 
According to a further embodiment, the cross-section of the respective 
discharge portion is greater than the cross-section of the portion of the 
transverse cooling water channel extending in the base of the valve drive 
pan and in the intermediate floor, respectively. In this way, the sealing 
face towards the cylinder block is optimized with respect to web widths 
and surface pressure. 
Furthermore, the transfer aperture between the longitudinal cooling water 
channel and a transverse cooling water channel is formed by a bore in the 
cylinder head. A plug or cover is inserted into the open end of the bore 
emerging from the cylinder head. Thus, the two types of cooling water 
channel can be produced more easily from a casting-technical point of 
view. Thus, the transfer apertures can be dimensioned more accurately. 
It can be advantageous to guide the discharge means of the transverse 
cooling water channel closely along the air intake channels, which carry 
expanded cooled inlet air. In this way, the cooling water carrying vapor 
bubbles is cooled and then the bubbles are condensed. 
For cylinder heads whose inlet and outlet channels in each cylinder portion 
are disposed transversely relative to the longitudinal direction on both 
longitudinal sides, i.e. for an assembly such as it is always used in 
multi-valve engines, the transfer aperture is positioned on the side of 
the outlet gas channels and the discharge means on the side of the inlet 
gas channels. In this way, any vapor bubbles which may develop are 
discharged from the longitudinal cooling water directly at their place of 
origin on the hotter side of the cylinder head. 
Furthermore, in cylinder heads with two or more inlet valves and two or 
more outlet valves per cylinder portion, the transverse cooling water 
channels extend between two transversely disposed valve guiding bores and 
two transversely disposed cylinder head bolt holes. In this way, the 
transverse cooling water channels can be arranged as close as possible to 
the center of the combustion chambers. 
The inventive method of producing a cylinder head casting includes the 
transverse cooling water channels and the longitudinal cooling water 
channel being cast without being connected to one another. The transfer 
apertures are each produced by a bore. The outer ends of the bores are 
closed by a plug or cover. 
The bores are preferably produced so as to start from a side face of the 
cylinder head. However, the bore may also start from the base of the valve 
drive pan. In this case, the bore enters the separating wall between the 
two cast channels approximately perpendicularly and can thus be accurately 
dimensioned. 
As already mentioned, the bent discharge means can either emerge from the 
deck face in a cast condition or the discharge means can emerge in a cast 
and/or bored condition from the cylinder head side face opposed to the 
above-mentioned cylinder head side face. 
A casting core to produce the cast transverse cooling water channels has 
the shape of a knee bend with core supports and core marks in the form of 
longitudinal extensions of the two legs. The core mark starting at the 
horizontal portion can be placed on a core mark of an outlet gas channel 
or it may be supported on a core mark support extending upwards from the 
bottom part of the casting die. The core mark at the end of the discharge 
means can be centered and positioned in the base of the casting die by 
means of a female core mark. 
From the following detailed description, taken in conjunction with the 
drawings and subjoined claims, other objects and advantages of the present 
invention will become apparent to those skilled in the art.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
FIGS. 1 and 2 will be described jointly below. The cylinder head 1 has a 
deck face 2 which is sealingly placed onto a cylinder block. A cover face 
3 has webs and onto which there is placed a cover. Adjoining the deck and 
cover faces are side faces 4, 5. The webs include longitudinal webs 6 
extending along the side face 4 which constitutes the inlet side. 
Longitudinal webs 7 extend along the longitudinal side 5 which constitutes 
the outlet gas channel side. Transverse webs 8 connect the longitudinal 
webs 6, 7 transversely relative to the longitudinal direction. The 
transverse webs 8 include recesses 9, 10 which are formed to receive 
camshaft bearings. 
A cylinder portion 11 of the cylinder head 1 is delimited by the bore 
centers of bolt holes 12, 13, 14, 15. A further cylinder portion 111 and a 
cylinder head end portion 211 follow the cylinder portion 11 in the 
longitudinal direction. Inside the bolt holes, valve tappet pockets 16, 
17, 18, 19 are provided. The pockets 16, 18 are provided for inlet valves 
and the pockets 17, 19 are provided for outlet valves. In the center 
between the valve tappet pockets a bore 20 is provided for an injection 
nozzle. The axes of the valve guiding bores and of the nozzle bores are 
indicated by dashed lines. 
In approximately the center between the side faces 4, 5 a horizontally 
extending intermediate floor 21 is provided. The floor 21, together with 
the webs 6, 7, forms the upwardly open valve drive pan 22. The floor 21 
together with a lower deck wall 23 of the cylinder head forms a 
longitudinal cooling water channel 24. The longitudinal cooling water 
channel 24 is closed on all sides. The longitudinal cooling water channel 
24 at the cylinder portions at the outer end is delimited by end walls of 
the cylinder head. 
An air intake channel 26 adjoins the longitudinal cooling water channel 24. 
The air intake channel 26 is partially positioned underneath the 
intermediate floor 21 and extends from a side entry neck 25 to the deck 
face 2. 
A transverse cooling water channel 27 is positioned above the longitudinal 
cooling water channel 24 and the air intake channel 26. The transverse 
cooling water channel 27 is formed in the intermediate floor 21 and 
changes into a substantially vertically extending discharge or end portion 
28. The discharge portion 28 is provided with an exit aperture 29 in the 
deck face 2. 
On the outlet side, the transverse cooling water channel 27 is widened by a 
bore 30. The bore 30 is outwardly closed by a pressed-in cover 31. The 
bore diameter of the bore 30 is large enough to guarantee the longitudinal 
cooling water channel to be cut into and for a transfer aperture to be 
obtained. 
The transfer aperture 32 is provided in a portion in which the longitudinal 
cooling water channel 24 forms a dome 33. Any vapor bubbles occurring in 
the longitudinal cooling water channel 24 are thus able to collect in the 
dome 33. The vapor bubbles move through the transfer aperture 32 via the 
transverse cooling water channel 27. The vapor bubbles are discharged into 
the cylinder block by a quantity of cooling water returning into the 
discharge portion 28. 
Because of the proximity of the air intake channel 26, into which flows 
expanded and cooled intake air, the cooling water is cooled, as a result 
of which, even in this portion, any vapor bubble which may have formed in 
the transverse cooling water channel 27 are condensed. In a plan view, the 
transverse cooling water channel 27 extends meander-like between two 
respective bolt holes 12, 13 and two respective valve tappet pockets 16, 
17 as seen in FIG. 2. 
FIGS. 3 and 4 will be described jointly below. The cylinder head details 
are not referred to individually. However, they are shown in the same way 
as in FIGS. 1 and 2. The transverse cooling water channel is formed by a 
casting core 51 with a transverse leg 52 and a vertical leg 53. The shape 
corresponds to the finished transverse cooling water channel with the 
exception of the widened bore. The core thus does not overlap with the 
longitudinal cooling water channel. At the end of the transverse leg 52, a 
core mark 54 is arranged which can be supported on a core mark of a core 
for a gas outlet channel or on a core mark support extending upwardly from 
the die base. A core mark 55 is formed at the end of the vertical leg 53. 
The core mark 55 can be inserted into a female core mark in the die base. 
While the above detailed description describes the preferred embodiment of 
the present invention, the invention is susceptible to modification, 
variation and alteration without deviating from the scope and fair meaning 
of the subjoined claims.