WO2008125254A1

WO2008125254A1 - Cylinder head for an internal combustion engine

Info

Publication number: WO2008125254A1
Application number: PCT/EP2008/002791
Authority: WO
Inventors: Ralf Quaas
Original assignee: Daimler Ag
Priority date: 2007-04-11
Filing date: 2008-04-09
Publication date: 2008-10-23
Also published as: DE102007017025A1

Abstract

The present invention relates to a cylinder head (1) for an internal combustion engine, comprising a bearing arrangement (2, 2'). The invention is characterized in that the bearing arrangement (2, 2') is configured to support a camshaft, forms an integral component of the cylinder head (1) and is made of a different material than the cylinder head (1).

Description

Cylinder head for an internal combustion engine

The present invention relates to a cylinder head for an internal combustion engine with a bearing assembly according to the preamble of claim 1. The invention also relates to a method for producing such a bearing assembly on a cylinder head.

From DE 100 26 216 B4 a cylinder head for an internal combustion engine in lightweight construction with at least one cast-in an external structure Eingussstück is known, wherein the outer structure and the sprue made of different materials. In order to achieve a reduction in weight, the sprue is made of a single material with a bearing bracket and free-standing towards a crankcase, wherein the bearing bracket is separated from the sprue by a break-separating process. In the area of a crankshaft bearing, the sprue has a radial opening which is at least partially filled with the material of the outer structure and in which an oil feed channel is arranged which connects an oil distributor channel to the crankshaft bearing.

Further bearing arrangements in cylinder heads of internal combustion engines are known, for example, from DE 34 04 866 C1 and DE 196 40 719 C1. In today's passenger car engines but also in heavy commercial vehicle engines, the camshafts are stored in an aluminum camshaft frame. For some engine variants, for reasons of space, a lower half of the camshaft frame is functionally integrated in the gray cast-iron cylinder head. The upper half of the camshaft frame, on the other hand, is made of die-cast aluminum and is screwed onto the cylinder head. Since the cylinder head consists of gray cast iron, depending on the embodiment, a large number of bearing shells must be introduced for supporting the camshaft. This leads to considerable additional expenditure in the mechanical production and assembly, which are due in particular to the pre-machining of the bore and the production of retaining grooves for the bearing shells, as well as in the assembly of the bearing shells themselves. In addition to these increased manufacturing and assembly costs are also costs for Bearings themselves on.

The present invention is concerned with the problem of manufacturing a bearing assembly for a camshaft in a cylinder head of an internal combustion engine manufacturing technology simpler and thus more cost-effectively.

According to the invention, this problem is solved by the subject matters of the independent claims. Advantageous embodiments are the subject of the dependent subclaims.

The present invention is based on the general idea to produce the bearing assembly of a different material to the cylinder head, in particular a light metal alloy, and at the same time form an integral part of the cylinder head, so that a previously required and expensive assembly of separate bearings can be avoided. This means that belonging to the cylinder head part of the bearing assembly, which usually divisible from Bearing shells is formed, is a direct part of the cylinder head.

In an advantageous development of the solution according to the invention, the cylinder head is designed as a cast part, in particular as a cast iron part, while the bearing arrangement for the camshaft is made of a light metal alloy, in particular an aluminum alloy. When designed as a cast cylinder head, as it is often used in large and heavy engines, it is necessary for trouble-free operation that bearings are used, which on the one hand have a required wear resistance and on the other hand ensure optimum storage of the shaft. In conventional internal combustion engines, this has been achieved by the fact that consisting of aluminum or an aluminum alloy bearing shells are mounted on the cylinder head or the camshaft in a camshaft frame

Aluminum (alloys) run, in which later the camshaft is stored. Due to the design of the bearing assembly as an integral part of the cylinder head, the bearing assemblies consisting of a light metal alloy can be arranged on the cylinder head in such a way that expensive and therefore expensive assembly of bearing shells can be avoided.

In an advantageous development of the solution according to the invention, the bearing arrangement is designed as a spray-applied bearing layer, in particular as an aluminum layer sprayed by means of laser wire spraying. The integration of the bearing assembly in the cylinder head by means of the above-mentioned laser wire injection method has the advantage that not only a frictional bond between the cylinder head and bearing assembly can be achieved here, but also a cohesive bond, creating a particularly strong Connection of the bearing shell with the cylinder head can be guaranteed.

Suitably, the bearing assembly is formed as a pressed-in bearing in the cylinder head bearing body. It is conceivable that a, preferably made of aluminum trained bearing body is pressed or pressed under pressure into a corresponding opening on the cylinder head. It is also conceivable that such a bearing body is firmly connected with the aid of a thermal joining process with the cylinder head. Such a thermal joining method may include, for example, a cooling of the bearing body to be pressed or a heating of the cylinder head immediately before the joining process, which set due to the temperature changes negative thermal expansions on the bearing body and positive expansions on the cylinder head, which after pressing the bearing body in the cylinder head due to the attenuating temperatures again so that, for example, the cooled bearing body expands after being pressed in the opening of the cylinder head and thereby clamped against them.

Other important features and advantages of the invention will become apparent from the dependent claims, from the drawings and from the associated figure description with reference to the drawings.

It is understood that the features mentioned above and those yet to be explained below can be used not only in the particular combination given, but also in other combinations or in isolation, without departing from the scope of the present invention.

Preferred embodiments of the invention are shown in the drawings and will be described in the following. Described spelling, wherein like reference numerals refer to the same or similar or functionally identical components.

It show, each schematically:

1 is a sectional view through a cylinder head with two bearing assemblies for each camshaft, wherein one of the bearing assemblies is designed as an inlay,

2 is a perspective view of a bearing assembly according to the invention, which is designed as an applied bearing layer,

Fig. 3 is a top view of a camshaft bearing, wherein a bearing assembly is formed as a pressed-bearing body.

1 far a cylinder head 1, two overhead camshaft bearings 2 and 2 ', which are integrally formed, in particular einstofflich, with the cylinder head 1. In this case, the camshaft bearings 2 and 2 'shown in FIG. 1 only show a respective lower camshaft bearing half, which is supplemented by a respective upper, not shown, camshaft bearing half. The upper camshaft bearing half can be designed, for example, as a camshaft bearing frame, in particular made of aluminum. The cylinder head 1 shown in FIG. 1 is representative of a cylinder head of a passenger car or even a heavy vehicle.

In particular, in commercial vehicle engines, the lower camshaft bearing halves, so for example, the lower half of the camshaft bearing frame, functionally in the cylinder head. 1 integrated, while the upper camshaft bearing halves are screwed after mounting the camshaft. According to the invention, the bearing assembly 2, 2 'forms an integral part of the cylinder head 1 and is made of a different material to the cylinder head 1, in particular of a light metal alloy. The cylinder head 1 itself is usually designed as a casting, in particular as a gray cast iron part. For the light alloy used for the bearing assembly 2, 2 'is particularly an aluminum alloy into consideration.

In order to ensure the most reliable connection between the bearing assembly 2, 2 'and the cylinder head 1, the bearing assembly 2, 2' and the cylinder head 1 non-positively and / or positively and / or cohesively connected to each other. In principle, four different embodiments of the bearing assemblies 2, 2 'and the connections between the bearing assemblies 2, 2' and the cylinder head 1 are possible.

A first possible connection or embodiment of the bearing assembly 2, 2 'is that the bearing assembly 2, 2' as in the cylinder head 1 integrated inlay 3, in particular as an aluminum inlay is formed. Such an inlay 3 is shown in FIG. 1 for the left bearing arrangement 2. A preparation of the cylinder head 1 is carried out in particular by cutting processes, such as clearing, while a fixation of the inlay 3 on the cylinder head 1, for example via fixing elements, not shown, in particular via fixing pins, which engage in associated fixing sleeves on the cylinder head 1.

A further embodiment of the bearing arrangement may be, for example, that the bearing assembly 2 'than sprayed bearing layer 4 is formed, as shown for example on the bearing assembly 2 'of FIG. 1. The spraying of the bearing layer 4 can be done for example by means of laser wire spraying or cold gas spraying. The bearing layer 4 is also preferably a light metal alloy, in particular an aluminum alloy. As shown in FIG. 1, the bearing layer 4 is applied by means of a laser 5, for example.

In a further embodiment of the bearing arrangement 2 according to the invention, this can be designed as an applied bearing layer 4 ', as shown for example in FIG. 2. The bearing layer 4 'is also preferably formed of a light metal alloy, in particular of an aluminum alloy. The bearing layer 4 'may be formed, for example, in the form of a thin sheet metal strip, which is pressed around the structure of the cylinder head 1, in particular by a cast iron structure, for example by a high-pressure ümformverfahren, so that thereby the geometry of the bearing assembly 2, 2' is formed ,

In the embodiment of the bearing assembly 2, 2 'according to the invention as shown in FIG. 3, the bearing assembly 2 is formed as a bearing body 6, which is or is pressed into the cylinder head 1. The bearing body 6 may be formed, for example, as an aluminum block.

Both in the embodiment of the bearing assembly 2, 2 'as inlay 3 (see Fig. 1) and as a bearing body 6 (see Fig. 3) and thermal joining method for connecting the bearing assembly 2, 2' with the cylinder head 1 can be used , Thus, for example, it is conceivable that the inlay 3 or the bearing body 6 is strongly cooled before being pressed in or before assembly, as a result of which it contracts. It is also conceivable that the cylinder head 1 is heated prior to assembly of the inlay 3 or of the bearing block 6, so that a prepared recess for receiving the inlay 3 or of the bearing block 6 expands in terms of its dimensions. After joining or pressing in a temperature compensation takes place, in which the inlay 3 and the bearing block 6 expands due to the then onset of heating, while the cylinder block 1 contracts due to the then onset of cooling. In this way, a particularly reliable connection between the bearing assembly 2, 2 'and the cylinder head 1 can be produced. Of course, it is also conceivable that the pressing in of the bearing body 6 into the associated recess on the cylinder head 1 takes place at room temperature, that is to say without the aid of thermal joining processes.

In summary, the essential features of the solution according to the invention can be characterized as follows:

The invention provides a bearing arrangement 2, 2 'for a camshaft, in particular a lower camshaft bearing part, which is currently formed as a cast part, in particular as a gray cast iron part, to be substituted by a light metal alloy, in particular by aluminum. As a result, a complex assembly process of bearing shells as well as an optionally required elaborate preparation of the cylinder head 1 for mounting the bearing shells omitted.

Claims

Daimler AG patent claims

1. Cylinder head (1) for an internal combustion engine with a bearing arrangement (2, 2 '), characterized in that the bearing arrangement (2, 2') is designed for mounting a camshaft and at least a part of the bearing assembly an integral part of the cylinder head (1 ), wherein the bearing assembly (2, 2 ') is made of a cylinder head (1) different material.

2. Cylinder head according to claim 1, characterized in that the cylinder head (1) as a casting, in particular as a gray cast iron part is formed, while the bearing assembly (2, 2 ') for the camshaft made of a light metal alloy, in particular of an aluminum alloy.

3. Cylinder head according to claim 1 or 2, characterized in that the bearing arrangement (2, 2 ') as in the cylinder head (1) integrated inlay (3), in particular as an aluminum inlay is formed.

4. Cylinder head according to claim 1 or 2, characterized in that the bearing arrangement (2, 2 ') is designed as a bearing body (6) pressed into the cylinder head (1).

5. Cylinder head according to claim 1 or 2, characterized in that the bearing arrangement (2, 2 ') as sprayed-on bearing layer (4), in particular as a sprayed by means of laser wire spraying or cold spraying aluminum bearing layer (4) is formed.

6. Cylinder head according to claim 1 or 2, characterized in that the bearing arrangement (2, 2 ') as an applied bearing layer (4'), in particular as an applied by means of high-pressure forming aluminum bearing layer is formed.

7. Cylinder head according to one of claims 1 to 6, characterized in that the bearing assembly (2, 2 ') and the cylinder head (1) non-positively and / or positively and / or cohesively connected.

8. A method for producing a bearing assembly (2, 2 ') for a camshaft on a cylinder head (1), wherein the bearing assembly (2, 2') integrated into the cylinder head (1) and from a cylinder head (1) different material will be produced.

9. The method according to claim 8, characterized in that a mechanical machining of the cylinder head (1), in particular a spaces, an introduction of an inlay (3), in particular an aluminum inlay and a fixing of the Inlays (3) by means of fixing elements, in particular via fixing pins.

10. The method according to claim 8, characterized in that a pressing in of a bearing body (6) in the cylinder head (1), wherein the pressing takes place either at room temperature or with the aid of thermal joining processes, such as shrinking and stretching.

11. The method according to claim 8, characterized in that the bearing arrangement (2, 2 ') in the form of an aluminum bearing layer (4) is sprayed by means of laser wire spraying.

12. The method according to claim 8, characterized in that the bearing arrangement (2, 2 ') in the form of an aluminum bearing layer (4, 4') is applied by means of high-pressure forming process.