1. Field of the Invention
The invention concerns a component of an internal combustion engine of the type defined in greater detail hereinafter. The invention further concerns a process for production of a component of an internal combustion engine.
2. Description of Related Art
In components of internal combustion engines, such as, for example, cylinder heads or pistons, a problem frequently occurs during thermal cycling in that, in the case of prevention of thermal expansion in higher loaded areas, mechanical tensions are induced in these areas which are so high that, due to the strong plasticization and the therewith associated material fatigue in these areas, crack formation occurs. This prevention of thermal expansion occurs because the thermally higher loaded materials tend to more strongly expand than the thermally less loaded materials. Since the thermally higher loaded areas are generally in the middle of the component, an outwards expansion is not possible, and the result is the above mentioned tensions, in particular pressure tensions, which during the cooling process convert into contraction tensions, which can exceed the materials' strength.
To solve the problems, it has been attempted in accordance with the general state of the art to improve the casting technique and to employ a subsequent thermal treatment to produce a fine and stable-as-possible microstructure. These measures, however, extend evenly across the entire component, so that the above-described problems cannot be overcome by these measures.
It is thus the task of the present invention to provide a component of an internal combustion engine and a process for production thereof in which, even in the case of varying high thermal loads distributed across different areas of the component, the problems known from the state of the art with regard to the failure of the component can be avoided.
The problem is inventively solved by the characteristics set forth below.
In accordance with the invention, the thermally highly loaded area of the component exhibits a lower thermal coefficient of expansion than the thermally less loaded area, which leads thereto, that the entire component can expand evenly during an increase in temperature. As a result thereof that the various areas of the inventive component expand evenly, there are smaller inhibitions in expansion, and thus smaller occurrence of the plastic deformation areas, so that upon heating and subsequent cooling essentially only small, or as the case may be, very minimal tensions are produced in the component, whereby the conventionally present danger of crack formation, attributable to the exceeding of the permissible tensions, is ultimately prevented.
By the inventive adaptation of the thermal coefficient of expansions to the thermal conditions within the component, the occurrence of a material fatiguing and/or a crack formation at a later point in time, or as the case may be, following higher loads, can be delayed, so that the inventive component can be employed in internal combustion engines with higher power and/or to lengthen the life span.
A process for production of an inventive component can be seen from the characteristics of claim 9.
Therein the base material of the component is melted and an additive is introduced, which results in a changed thermal coefficient of expansion in the thermally higher loaded area. This manner of proceeding makes possible a particularly precise control of the alloy composition in the thermally higher loaded area.
Advantageous embodiments of the invention are indicated in the dependent claims. In the following, an illustrative example of invention will be described in principle on the basis of the figure.
There is shown in:
The cylinder head 1a includes multiple valve bores 3, between which a thermally higher loaded area 4 is located, which in the following is referred to as the intermediate area 4a. This intermediate area 4a is, during operation of the internal combustion engine, higher thermally loaded than the rest of the component 1 or, as the case may be, than other areas 5 of the component 1. Since the internal combustion engine associated with the cylinder head 1a has three, or as the case may be, six cylinders, a total of three intermediate areas 4a are provided. Since four valve bores 3 are provided for each cylinder, the intermediate areas 4a essentially have a cross-shaped design. If two valve bores 3 were provided per cylinder, then the intermediate areas 2a could also have a linear design. In the case of a piston, the thermally higher loaded area 4 would likely be the piston bowl. Of course, the number of cylinders in the internal combustion engine could be varied as desired.
If the component 1 is comprised in its entirety of a homogeneous material, preferably of an aluminum material, in particular, an aluminum-silicon alloy, it would exhibit a constant thermal co-efficient of expansion α1. The temperature of the component 1 is, in the case of the not-heated condition as shown in
If, as shown in
In order to produce the component 1, the higher loaded area 4 is melted, so that a melt pool 5 results, as shown in
As shown in
From the illustration according to
Finally,
Now that the invention has been described, we claim:
Number | Date | Country | Kind |
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103 53 473.3 | Nov 2003 | DE | national |
This application is a national stage of PCT/EP2004/012413 filed Nov. 3, 2004 and based upon DE 103 53 473.3 filed on Nov. 15, 2003 under the International Convention.
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/EP04/12413 | 11/3/2004 | WO | 7/20/2006 |