EP1645746A1 - Cylinder head for an engine - Google Patents

Abstract

The cylinder head (1) has a crank case side sealing surface (2) in which two combustion chamber roofs (4,4') are arranged and separated by a stud (3) whereby sealing surface has a bore (5) in stud area towards cylinder axis.

Description

The invention relates to a cylinder head for an internal combustion engine according to the features in the preamble of patent claim 1.

It is based on German Patent DE 4342800 C2. In this, a cylinder head for a liquid-cooled internal combustion engine is described, the cylinder areas are each separated by a web. So that the webs and thus also the sensitive valve guides, the thermally highly loaded cylinder head are not deformed by thermal expansion, the webs have circular-shaped depressions. These recesses form soft areas in the cylinder head, which absorb thermal expansion or tension that occurs and thus prevent deformation of the valve guides and at the same time leakage of the webs during operation of the internal combustion engine.

In modern engines, especially in inline engines, the webs are reduced as much as possible in their strength to reduce weight and to reduce the cylinder head length (space), d. H. the cylinder spacing is minimized. As a result of this material weakening, it is scarcely possible to introduce circular-arc depressions to minimize thermal expansion.

The object of the present invention is to provide a new method of minimizing the thermal expansion of a narrow web between two cylinders in a cylinder head.

This object is achieved by the feature in the characterizing part of patent claim 1. Due to the inventive design, the web material expands when heated in the direction of the bore, instead of in the longitudinal direction or in the direction of the crankcase. By this measure, the cylinder head gasket either easier in the web area, d. H. also cost-effective, or the web area can be made even slimmer.

The embodiment according to claim 2 allows the introduction of a plurality of holes in the direction of the cylinder axis, even with narrow webs.

The embodiment according to claim 3 allows the distribution of the holes according to static conditions, d. H. in accordance with the occurring thermal deformations during operation of the internal combustion engine. For example, the thermal expansion of the land area can be determined by means of a numerical simulation, and then the relief holes can be optimally arranged. Depending on the thermal expansion, several holes can be stochastically distributed or arranged symmetrically to the combustion chamber roofs or a combination of both types of distribution.

By producing the bore by means of laser or ultrasonic drilling according to claim 4, this can be introduced quickly and inexpensively.

Fig. 1

zeigt schematisch die Aufsicht auf einen Ausschnitt einer Montagefläche eines Zylinderkopfs.

In the following the invention with reference to a preferred embodiment in a single figure is explained in more detail.

Fig. 1

schematically shows the top view of a section of a mounting surface of a cylinder head.

A cylinder head 1 is bounded on two outer sides by a respective first outer wall 1a and a second outer wall 1b. Between the outer walls 1 a, 1 b are two half dome-shaped, incorporated in the cylinder head 1 combustion chamber roofs 4, 4 ', which are separated by a web 3, which is also part of the cylinder head 1. Between the combustion chamber roofs 4, 4 'are In the present case, the bores 5 are distributed symmetrically with respect to the combustion chamber roofs 4, 4 'and are largely aligned in the direction of a cylinder axis, not shown, in the web area 3 in a crankcase-side sealing surface. A series of bores 5 extends in a straight line in the expansion direction of the web 3 between the combustion chamber roofs 4, 4 ', two further rows of bores 5 extend coaxially to the combustion chamber roofs 4, 4' in the web area 3.

The holes 5 in the exemplary embodiment have a bore diameter of 0.05 mm and a bore depth of 1 mm. In further embodiments, the bore diameter may also be between 0.01 and 1 mm and the bore depth between 0.1 and 8 mm. In addition to a symmetrical distribution of the holes 5 around the combustion chamber roofs 4, 4 'is also a stochastic distribution of the holes 5 is possible or a combination of the two types of distribution.

The holes 5 were made by laser drilling, but can also be produced by ultrasonic drilling.

Due to the embodiment of the invention, the deformation and thus leakage between the combustion chamber roofs 4, 4 'is reduced by the thermal expansion of the webs 3. Furthermore, a concomitant reduction in the surface pressure of a cylinder head gasket is achieved. The use of this perforation is also possible with modern inline engines with extremely narrow webs 3. In addition, it is a quick and inexpensive method to avoid the disadvantages mentioned above.

LIST OF REFERENCE NUMBERS

1

cylinder head

1a

first outer wall

1 b

second outer wall

2

sealing surface

3

web

4, 4 '

Combustion chamber roof

5

drilling

Claims (4)

Cylinder head (1) for an internal combustion engine with a crankcase side sealing surface (2) in which at least two of a web (3) separate combustion chamber roofs (4, 4 ') are arranged,
characterized in that the sealing surface (2) in the web region at least one bore (5) has substantially in the direction of a cylinder axis. Cylinder head according to claim 1,
characterized in that the bore (5) has a bore diameter between 0.01 and 1 mm, and a bore depth between 0.1 and 8 mm. Cylinder head according to claim 1 or 2,
characterized in that in the web region a plurality of bores (5) are arranged symmetrically to the combustion chamber roofs (4, 4 ') and / or distributed stochastically. Cylinder head according to one of the claims 1 to 3,
characterized in that the bore (5) is produced by means of laser drilling or ultrasonic drilling.

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