DE29818763U1 - Sandwich flange - Google Patents

Description

Designation: Sandwich flange
Description

The invention relates to a sandwich flange for connecting an exhaust manifold to the engine block of an internal combustion engine or to a downstream point of the exhaust system with a duct system for supplying secondary air to the exhaust gases, the sandwich flange being formed from several plates.

Exhaust flange systems, such as those used between the engine block and the manifold or in the downstream parts of the exhaust system, currently consist of solid cast or forged material into which the corresponding mounts for the manifold and air holes are machined. This obviously represents a considerable manufacturing effort and also results in a high weight. Another problem is welding the manifold pipes into the mounts on the exhaust flange.

Attempts have also already been made to produce the exhaust flange using two flange parts, with the connection being made by soldering. These were fine-stamped parts with a deep-drawn sheet metal cover made of thinner material on top, in which the channels for the secondary air were embossed or deep-drawn.

From DE 89 14 153 Ul a sandwich flange for connecting an exhaust manifold to the engine block of an internal combustion engine or at a downstream point in the exhaust system with a channel for supplying secondary air to the exhaust gases is known. This flange is made up of several plates and forms the preamble of claim 1. Here, outer plates - corresponding to the shape of the flange - are connected to an inner plate in which a channel system for

the supply of secondary air is provided, are connected to each other by brazing.

In the flange according to DE 297 14 479 Ul, the corresponding plates are also soldered together, which is not a particularly easy solution to master in terms of manufacturing technology, since reject-free brazing is only possible if strict boundary conditions are met.

Similar flange systems are known from EP 719 915 Al, DE 196 07 184 Cl, EP 765 995 Al or DE 34 34 288 Al, in which the surfaces forming the channel are welded together. Welding these relatively large components is a process that is not easy to master technologically and requires a relatively high level of effort in terms of the parameters to be observed. In particular, with these components, which have to withstand high thermal cycling stresses during operation, attention must be paid to precise and consistently durable seams. This is not always achieved by conventional welding processes, which leads to a relatively high rejection rate.

The object of the invention is therefore to provide a sandwich flange which has a high manufacturing quality and is cheaper to manufacture.

This object is achieved according to the invention by a sandwich flange, in which at least the plates forming the channel system are connected to one another by means of laser welding.

The inventive use of the known laser welding process on these thermally highly stressed components leads to relatively low manufacturing costs. Because only a small amount of waste is produced and the weld seams are nevertheless sufficiently tight, the welding processes can be automated. The laser welding,

which, for example, connect the channel side walls with the channel bottom walls, result in a tight, absolutely closed weld seam that reliably withstands the thermal cycling stresses during normal operation of a combustion engine.

Laser welding according to the invention makes it possible for the first time to permanently and gas-tightly join different material pairs together. Cast iron can be joined to steel, stainless steel to steel or steel to steel, which gives the designer great freedom in the choice of material. The base flange can be made of cast iron, while the second plate arranged on top of it can be made of steel, i.e. a material that is much easier to process.

Another special feature of laser welding is that the weld seam does not have to be accessible from the outside, but can be hidden, since the laser beam can pass through a metal plate - if it is not too thick - and create a laser seam on the back of the plate, which then attaches this plate to the metal piece underneath in a gas-tight manner. In this specific case, for example, a thin steel channel plate is placed on a solid cast flange part and the laser beam is directed onto the channel plate at the points to be welded. The laser beam penetrates the channel plate, melts it and, when it cools, welds the channel plate to the cast part. This means that - with a suitably programmable welding robot - any welding contour can be produced quickly and in a gas-tight manner.

The weld seam can therefore preferably be carried out using an automatic machine, whereby the course of the seam is then stored in the computer and precisely followed by the machine.

In one embodiment, the channel-forming plates are fine-stamped parts, embossed parts or deep-drawn parts. These processes can be used to create channels of practically any size.

geometry that meets all the designers' requirements for modern secondary air routing.

Of course, it is also possible to use not just two, but three or more fine-stamped parts, embossed parts or deep-drawn parts.

Further advantages, features and areas of application of the present invention emerge from the following description of an embodiment with reference to the drawing. All described and/or illustrated features form the subject matter of the present invention, either individually or in any combination, regardless of their summary in the claims or their reference back to them.

Figures 1, 2 and 3 each show a sandwich flange according to the invention in plan view and in two sections.

In the embodiment according to Figure 1, the sandwich flange consists essentially of two plate-shaped components, namely the flange plate 2 and the channel plate 4. In this embodiment, the flange plate 2 has four large openings for the four exhaust channels, next to each of which two through holes (screw channels 12) are provided for fastening the flange, e.g. to the engine block of the internal combustion engine. The channel plate 4 has a similar shape, rests on the flange plate 2 and, as can be seen particularly in the sectional view B-B, has recesses that form a channel. The recesses are provided where corresponding recesses are arranged in the flange plate 2, so that when the flange plate 2 and the channel plate 4 are placed on top of one another, these recesses form the air channel 6, which, as can be seen particularly in the section C-C, brings secondary air from an intake nozzle 10 near the respective connection nozzles for the exhaust pipes or other places on the exhaust pipes.

Four (not shown) connection pieces are provided in the usual way to hold the exhaust pipes. The screw channels 12 allow the sandwich flange to be attached to the engine block or to another location further downstream of the exhaust system. The weld seam 8 is laser welded according to the invention. As can be seen in section B-B, the seam is not accessible from the outside, but is located inside between parts 2 and 4. It was created by laser welding through the plate 4. Laser welding makes it possible to attach the two plates 2 and 4 to one another absolutely tightly and securely, whereby these properties are retained even when internal combustion engines are subjected to temperature changes. The channel 6 leads from the central intake manifold 10 to the right and to the left to the two left and right connection elements, whereby the secondary air is directed to the exhaust channels. The number of exhaust channels corresponds to the number of cylinders in the engine.

As can be seen in sections A-A, B-B and C-C, the two flange plates 2 and 4 are approximately the same thickness. The flange system here therefore consists of two plates, although of course versions with more than two plates are possible.

Figure 2 shows a further embodiment of a sandwich flange according to the invention, in which the flange plate 2 is made significantly thicker than the channel plate 4. While the flange plate 2 consists of a fine-stamped part made of steel, the channel plate 4 is a deep-drawn or embossed steel plate.

Fig. 3 shows a further embodiment of the invention, in which an intermediate plate 3 is provided which is welded to four base flanges 2a on the engine side, in particular in the hole area 2b, laser-welded in a gas-tight manner. In Fig. 3 above, the four base flanges 2a are covered by the intermediate plate 3 and are therefore only shown in dashed lines. On the other side of the intermediate plate 3, i.e. in Fig. 3 above on the visible side,

In the lower area, the channel plate 4 is again welded using a laser beam; the laser welding line 7 is drawn as the welding contour of the channel plate. The intermediate plate 3 and the channel plate 4 again form the air channel 6.

Claims (3)

Protection claims 1. Sandwich flange for connecting an exhaust manifold to the engine block of an internal combustion engine or a downstream point of the exhaust system with a channel for supplying secondary air to the exhaust gases, the sandwich flange being formed from several plates (2, 3, 4), characterized in that at least the plates (2, 3, 4) forming the channel are connected to one another by means of laser welding. 2. Sandwich flange according to claim 1, characterized in that one or more of the channel-forming plates (2, 4) are (fine) stamped parts, embossed parts or deep-drawn parts. 3. Sandwich flange according to claim 1 or claim 2, characterized by different material pairings.