Exhaust manifold

IS 2 178 683 T3

DESCRIPTION

Exhaust gas elbow

The invention is based on an insulated exhaust gas elbow with an air gap for combustion engines according to the preassembly of claim 1.

Until now, it has been common for exhaust gas elbows of this type to have a collector tube, which roughly runs parallel or in the longitudinal direction of the cylinder flange made flat. The tubes emerging from the cylinder flange are then joined to the edges of the openings in the header tube in such a way that the longitudinal direction of the cylinder tubes forms an essentially right angle with the longitudinal direction of the header tube. In order to improve the flow behavior, attempts have already been made to make the cylinder tubes slightly bent, so that they open into the collector tube diagonally.

For joining, it is possible to provide a neck to the cylinder tube to be joined, which is joined to the tube by means of a welding bead.

This solution has the disadvantage that a high production effort has to be made due to the manufacture of the holes in the tubes, the adaptation of the neck to the tube and the welding beads. Because the weld neck is opposite the direction of expansion of the collector tube, cracks appear. The entrance of the gas from the cylinder tube with an angle opposite to the longitudinal axis leads to the fact that the wall located in the opposite part admits the hot gas, in such a way that temperatures are reached there too high, in case of combustion. of the drills. Furthermore, due to the diagonal inflow, a vortex is produced which has a disadvantageous effect on the optimum gas velocity.

An insulated exhaust gas elbow with an air gap having the characteristics of the first part of claim 1 (DE-A42 26 171) is already known.

It is also known in combustion engines to place the ends of self-supporting exhaust pipes in parallel with each other and leaning against each other. In this way it must be achieved that the gas pulses coming from each cylinder tube lead at different times to another exhaust gas tube which was continued (WO 92-03639).

The invention is based on the aim of creating an exhaust gas elbow which is improved from the hydrodynamic and technical manufacturing point of view.

For the solution of this purpose, the invention proposes an elbow with the particularities mentioned in claim 1. The improvements of the invention are the subject of the secondary claims.

The invention then proposes that in a case with three cylinder tubes it is provided that firstly the first two cylinder tubes are connected in parallel and are connected with an axially oriented intermediate collecting tube. This intermediate collector tube can be oriented and connected again in parallel with the third cylinder tube, producing a connection, for example by introduction, with the collector tube running in the same direction. In this case, with the junction of the intermediate collector tube with the third cylinder tube, the intermediate collector tube has a cross section twice as large as the cylinder tube, since it must accommodate the gas stream from two cylinder tubes.

It is possible to proceed in an analogous way with the union of four or more cylinder tubes.

In the constellation mentioned at the beginning, where the longitudinal direction of the collector tube is transverse to the directions of the cylinder tubes placed on the cylinder flange, the first two cylinder tubes are made in such a way that they have the direction of the intermediate collector tube. This bending, for example 90 °, can be carried out in such a way as to produce a progressive deflection of the gas jet. In their extreme zone, that is, when the gas flows into the intermediate collector tube, the gases already have the same direction as the intermediate collector tube, so that no partial local inlet appears in the walls. The drilling of holes in the wall of the intermediate collector tube is eliminated, since the first two cylinder tubes are inserted axially into the intermediate collector tube open there anyway, and / or are joined with oil.

Since the gas streams leaving the first two cylinder tubes and entering the intermediate collector tube are already oriented in parallel with each other, the problem of reciprocal clogging of the gas streams does not reappear. This leads to an improvement in the characteristics of the engine. It can be ensured by selecting the cross section that the flow velocity of the two gas streams is the same as they exit the cylinder tubes. The same can be applied to the third cylinder tube and eventually to other cylinder tubes.

In a further development of the invention, provision can be made for the ends of the cylinder tubes connected and positioned adjacent to each other to be positioned adjacent to each other in the longitudinal direction on a particularly flat surface.

The invention proposes that the cross section of the joined ends of the first two cylinder tubes can correspond respectively to a semi-circle, a semi-oval shape or another half mold. If, for example, the intermediate collecting tube has a circular cross-section, the first two cylinder tubes have a semicircular cross-section at their end regions. With an intermediate collecting tube made in an oval shape, the cross section would anaologously have a semi-oval shape.

According to the invention, provision can be made for the intermediate collecting tubes to be secured against slipping by means of lugs, bulges or projections, these being arranged in such a way that temperature expansions are still possible.

The parallel orientation of the joined ends of the cylinder tubes proposed by the invention is usable especially in elbows for isolated exhaust gases with an air gap,

ES 2 178 683 T3 in which the system of inner tubes that conducts the gas is arranged inside an outer casing, which is connected to the cylinder flange and the manifold flange, in particular welded. In this case, the connection between the cylinder tubes, the collector tube and the intermediate collector tubes is carried out by means of a simple introduction, since a gas tightness is not necessary. By suitable shaping and close fitting of each part close to one another, it is possible to ensure that low permeability is maintained.

Other characteristics, features and advantages are listed in the claims, the text of which has been made with reference to the content of the description, of the following description of a preferred embodiment of the invention as well as based on the drawing. They are shown in this:

Figure 1, a schematic side view of an exhaust gas elbow, in which the cylinder flange made in one piece protrudes on a flange of the manifold,

Figure 2, cross sections with the arrangement of figure 1 in two positions,

Figure 3, cross sections with a similar arrangement in another exterior shape,

Figure 4, a partial longitudinal section of an exhaust gas elbow with three cylinder tubes.

Figure 5, a longitudinal section of the exhaust gas elbow of figure 1.

The exhaust gas elbow shown in FIG. 1 contains a flange 1, which on its left side in FIG. 1, extending somewhat more than two thirds of the total length, is made as cylinder flange 2. In its adjacent right part it closes, the flange 1 is realized as a flange 3 of the manifold. Starting from the cylinder flange 2, three cylinder tubes 4 are attached to the flange, for example by welding. Each cylinder tube 4 was connected with an opening in the cylinder flange 2, so that the gas jet entering through the opening of the flange 2 is guided by the corresponding cylinder tube 4.

The cylinder tubes 4 are attached to the cylinder flange 2 with approximately a right angle and extend thereafter for a quarter arc in one direction, essentially running parallel or slightly diagonal to the surface of the flange 1.

The first cylinder tube, in Figure 1 completely to the left, extends beyond the second cylinder tube 4, where the first two cylinder tubes 4 are placed side by side and in their end areas 5 run in parallel between them. The two end zones 5 of the first two cylinder tubes 4 are inserted into an intermediate collecting tube 6, the axis of which has the same direction as the end zones 5 of the cylinder tubes 4. Therefore, no deviation of the two gas jets emerging from the two cylinder tubes 4 appears in the intermediate collecting tube 6.

The intermediate collector tube 6 then runs in an approximately straight manner until the collector tube 7 also oriented on the same axis.

The third cylinder tube 4, which likewise runs following a quarter of a curved circular arc, is parallel in its end zone to the end zone of the intermediate collecting pipe 6 and was supported with its wall to the west. It is inserted next to the intermediate collector tube 6 resting on the end of the collector tube 7, so that both the gas jet that comes out of the intermediate collector tube 6 and the gas jet of the cylinder tube 4 run parallel to each other when entering the collector tube 7. The collector tube 7 then receives all the gas jets and conducts them through the arc 8 existing at its end to the part 3 of the flange that acted as the flange of the collector.

In an exhaust gas elbow for a combustion engine an outer casing, for example in the form of a covering, is placed around the arrangement of the tubes that can be seen in figure 1, which was welded to the flange 1 so that gas tight.

Figure 2 shows in its halves on the right a section of the arrangement of Figure 1 in the longitudinal direction of line BB, that is, in the position, in which the end areas 5 of the two cylinder tubes 4 They flow into the intermediate collector tube with a circular cross section. The cross section of the two end zones 5 corresponds to a semicorcle, with a separation surface that runs flat between the two walls, which are located supporting one another and are watertight. The intermediate collector tube 6 is positioned with a close fit around the two end zones 5. The two end zones 5 of the first two cylinder tubes 4 have the same cross-sectional shape and the same cross-sectional dimensions. As the same quantity of gas flows from the two cylinder tubes, the same speed of the two gas streams is thus achieved when they are introduced into the intermediate collecting tube 6.

Figure 2 shows on the left a cross section of the longitudinal arrangement of the AA lone. In this position, the area of ​​the end 5 of the third cylinder tube 4 opens into the collector tube 7 together with the area of ​​the end of the intermediate collector tube 6. Again the area of ​​the end of the intermediate collector tube 6 is located along a surface flat spacing in the area of ​​the end of the third cylinder tube 4. The cross section of the intermediate collector tube 6 is, however, approximately twice as large as the cross section of the cylinder tube 4, because the gas stream from the intermediate collector tube 6 exits the first two cylinder tubes 4.

Figure 3 shows analogous representations in an exhaust gas system, where both the collector tube and the intermediate collector tube 6 have an oval cross section.

Figure 4 shows a longitudinal section

ES 2 178 683 T3 of a part of an arrangement on an enlarged scale. The cylinder flange 2 has several openings 10 already mentioned, from which the exhaust gases of the combustion engine exit. In each opening 10 the end of a cylinder tube 4 corresponding to the engine is positioned and fixedly welded. The opposite ends 5 of the first two cylinder tubes 4 are inserted into the intermediate collecting tube 6. The two ends 5 of the first two cylinder tubes 4 are not welded, nor welded with tin, neither between them nor with the intermediate collecting tube 6, so that due to the suppression of such a joint they can continue to be reduced. the costs. The first cylinder tube 4 contains, just before its end region 5, an outward-facing projection in the form of a bulge 11, which extends, for example, over a part of its perimeter.

At the opposite end, the intermediate collector tube 6, together with the third cylinder tube 4 supported by oil, is inserted into the collector tube 7. Here the intermediate collector tube 6 has a bulge 12 that corresponds to bulge 11. The The distance of the bulge 12 from the edge of the corresponding end of the intermediate collecting tube 6 is chosen in such a way that the thermal stresses can be absorbed.

The two bulges 11, 12 must prevent the intermediate collector tube 7 from slipping under stress caused by changes in temperatures and shocks.

As can be deduced from FIG. 4, the ends 5 of the cylinder tubes 4 and / or the end region of the intermediate collecting tube 6 are inserted in a relatively short section into the respective rear component. The arrangement was chosen in such a way that each gas conducting tube element was inserted internally into the rear tube element. The two joined ends 5 of the two first cylinder tubes 4 end in the same plane, as do the third cylinder tube 4 and the intermediate collecting tube 6.

Figure 5 again shows the arrangement of Figure 1, where this time at the ends of the flange 1 an outer casing 13 is shown in broken form, which along the edge of the flange 1 is welded with this. The flange 13 can also have holes 14, which coincide with the corresponding connection holes 15 of the flange 1.