ES2261325T3 - EXHAUST ELBOW FOR DRIVING EXHAUST GASES OF A COMBUSTION ENGINE. - Google Patents

Abstract

The manifold has an outer shell (2) extending along the row of outlet openings of the cylinders, and an inner shell to form an insulating air gap between the two shells. A common outlet opening (10') is formed on a centre section of the manifold and for each of the four or more cylinders there is an inlet flange (2 to 8) located on the exhaust inlet side whereby the flanges of the two middle cylinders are connected together through a web. The web has a through bore between the flanges so that it can be heated up by the hot exhaust gases.

Description

Exhaust elbow for gas conduction exhaust of a combustion engine.

The invention relates to an exhaust elbow for the conduction of the exhaust gases of a combustion engine with, preferably, six cylinders arranged in line.

In an in-line engine with more than three cylinders, an exhaust elbow may be constructed as a structure elongated tubular that extends along the opening line of exhaust gas from the combustion engine, being arranged an inlet flange on the outlet elbow in front of each exhaust opening of the combustion engine and being arranged a common outlet flange in a central section of the exhaust elbow. TO consequence of the high temperature of the exhaust gases, the elbow Exhaust expands in its longitudinal extent by a measure significantly larger than that of the combustion engine or cylinder head correspondent. For the exhaust elbow to withstand the loads mechanical based on thermal expansion, said exhaust elbow it has to be of very robust construction and, therefore, thick wall and heavy, having to be possible, in addition, a relative movement of the inlet flanges of the exhaust elbow with respect to the Combustion engine outlet openings to prevent cracking.

Elbows are known in the state of the art cast iron, single wall composite elbows and elbows double wall exhaust, the so-called exhaust elbows isolated by air gap (LSI exhaust elbows). The exhaust elbows of a single wall and double wall are usually composed of tubes, helmets, flanges, etc. soldiers with each other.

A casting elbow has a wall thickness large which, conditioned by manufacturing, is more than 3 mm, which that motivates a high mechanical resistance against an overload of the material based on thermal expansion. However it is disadvantageous the high weight of the casting elbow and it is also disadvantageous the high thermal capacity linked to it, which leads to strong cooling of the exhaust gas, especially in the warm-up phase of the engine. In addition, the elbow of foundry has a poor thermal insulation capacity and thus energy is lost for the operation of a exhaust gas turbocharger. Also, the temperature of starting an exhaust gas purification device and / or the operating temperature of a gas purification device Exhaust only reached slowly.

A single wall exhaust gas elbow, constituted by tubes, helmets and flanges welded together, it is certainly lighter than cast iron elbow, but its strength mechanical versus material loads based on a dilation Thermal is also smaller. Also, an exhaust elbow of a single wall welded assembled has poor capacities of thermal insulation and presents in this aspect the same disadvantages than the casting elbow.

A double wall exhaust elbow, isolated by air gap, has, on the one hand, good insulation properties thermal and, on the other hand, for reasons of weight saving and lower thermal capacity, an exhaust elbow insulated by air gap is consisting of relatively thin wall components, which it can easily lead to an overload of the material in the form of thermal deformations and thermal cracks, especially in the case of large construction lengths. For avoid this, the exhaust elbows insulated by air gap to large construction lengths, such as for four engines cylinders and especially six cylinders in line, are built in several pieces as represented, for example, in the DE 199 52 648 A1.

US 5 220 789 discloses an elbow of thin-walled exhaust, consisting of two helmets, for an engine multiple cylinders in line, where the two central flanges they are connected to each other by means of a bridge of union.

In the realization in several pieces are disadvantageous high manufacturing complexity and high costs linked to it. In addition, the realization in several pieces is unfavorable in supercharged engines, since the feeder does not It can be placed close to the combustion engine and therefore they have to accept energy losses as a result of cooling of exhaust gases.

The invention is based on the problem of provide an exhaust elbow insulated by air gap in one-piece construction for four and more engines cylinders in line, in which there are no overloads of the material in the form of cracks or plastic deformations based on thermal expansion

This problem is solved with the characteristics of claim 1 because an elbow of double wall exhaust, insulated by air gap, has a large number of inlet flanges on the inlet side of the gases from Exhaust, with the inlet flanges of the two cylinders attached central to each other through a connecting bridge, which has manufactured from a material that has a dilation thermal higher than the material of the remaining components of the exhaust elbow. However, when the elbow is heated air gap insulated exhaust, the joint bridge between the two central cylinders, the connecting bridge contributes to the thermal expansion of the exhaust elbow, especially in the section center of said exhaust elbow, in which the flange of common exhaust elbow outlet. Due to the realization constructive in which the two central flanges are joined to through the connecting bridge forming a double flange, and in which the External cylinder flanges are maintained as flanges independent individuals, a level of tensions is obtained favorable in the outer hull of the exhaust elbow, so that the thermal operating voltages that occur in the hull exterior as a result of the different thermal variation of the length between the cylinder head and the exhaust elbow do not lead to plastic deformations or cracks in the outer shell. Flanges individual edge cylinders allow the elbow to escape have as much freedom of movement as possible in these areas less thermally charged.

Due to the advantageous configuration of the elbow of escape it is possible to configure the helmet with a thinner wall bearing, be it the inner helmet or preferably the outer helmet, which saves weight and, therefore, costs. It is thus possible provide an insulated exhaust elbow by air gap with a small thermal capacity, so you can get a fast arrival at the operating temperature and therefore a rapid initiation of post-treatment of exhaust gas during cold start. In addition, the exhaust elbow has a good insulation action, so that the minimum heat losses from the exhaust gas, which leads to a level of higher temperature of the exhaust gases and therefore causes faster initiation of subsequent treatment of gas escape during cold start and eventually an offer of increased enthalpy for an exhaust gas turbocharger possibly connected. With the advantageous configuration of the present exhaust elbow a lightweight exhaust elbow is provided and thermally insulated with a high lifespan, which can be of single or single-piece construction even on a six-engine cylinders in line.

In an advantageous embodiment of the gas elbow of Exhaust the connecting bridge is provided with a hole for that said connecting bridge can be heated by exhaust gases hot so as to contribute to faster warming of the junction bridge, thus contributing additionally to the thermal expansion in the central section of the exhaust elbow.

In another advantageous embodiment the connecting bridge It can be provided with thermal insulation, so quickly reaches its action that contributes to the dilation of the central section of the exhaust elbow and this action during operation.

In an advantageous embodiment the inner hull It has the task of driving the exhaust gases of the flanges of input to the common output flange. The inner hull is formed by several pieces, the inner hull pieces being joined in areas of great thermal expansion through a sliding seat. The outer shell then takes over the bearing function and is Gas-tight construction. Due to this configuration with sliding seats in the inner hull it is possible to award the inner hull - which is exposed to higher thermal stresses of operation than the outer hull - a slack of movement optimal Also, due to this configuration you can build the outer helmet with thinner wall, since said outer helmet does not it is requested with thermal expansion stresses of the hull inside.

The subordinate claims indicate other embodiments of the invention.

An example of preferred embodiment with reference to the attached drawings, in  those that show:

Figure 1, a perspective view of the elbow air gap insulated exhaust (LSI exhaust elbow) running One-piece for a six-cylinder in-line engine;

Figure 2, a sectional view of the exhaust elbow along the section line CC according to the
figure 3;

Figure 3, a sectional view of the exhaust elbow along section line BB according to the
figure 2;

Figure 4, a sectional view of the elbow of exhaust gas along section line A-A according to figure 2;

Figure 5, an exploded view of all individual parts of the exhaust elbow according to figure 1;

Figure 6, an exploded view of the groups main construction of the exhaust elbow according to figure 1;

Figure 7, the grouping of pipes in the output flange;

Figure 8, a modified arrangement of junction bridge between the central inlet flanges;

Figure 9, a representation of tensions thermal performance of the outer hull of the exhaust elbow when no connecting bridge between the flanges is provided central individual; Y

Figure 10, a representation of the operating thermal stresses of the outer hull of the elbow Exhaust when a connecting bridge between the flanges is provided central individual.

According to figures 1 to 6, the structure of an exhaust elbow insulated by air gap for a Inline six cylinder engine (not shown). The exhaust elbow is extends substantially along the outlet openings of the combustion engine (not shown). The exhaust elbow has a inner helmet 1 which is surrounded by an outer helmet 2, so that between the inner helmet 1 and the outer helmet 2 a air gap 13. On the exhaust gas inlet side are juxtaposed six individual inlet flanges 3 to 8 facing each other to the combustion engine outlet openings, each having inlet flange 3 to 8 a respective oval inlet opening 3 ' at 8 'and two respective fixing holes 15 to fix them to the combustion engine Both the outer zone of the outer hull 2 and the extreme zone of the inner hull 1 penetrates juxtaposed in each inlet opening 3 'to 8' such that the outer hull 2 penetrates to a greater extent in the respective inlet opening 3 'to 8' than the inner helmet 1. The inner helmet 1 and the outer helmet 2 they are connected to the respective input flange 3 to 8 through a common welding seam 9 arranged on the inner surface of each inlet opening 3 'to 8'.

In a central section of the exhaust elbow, the exhaust gases introduced through the inlet flanges 3 to 8 meet in a common outlet flange. The plane 11 of the outlet flange 10 is rotated 90 ° with respect to the plane common of the inlet flanges around an axis parallel to the longitudinal extension of the exhaust gas elbow, so that the exhaust gases in the central section of the exhaust elbow are deflected in front of plane 12 of the inlet flanges at 90 ° with respect to plane 11 of the output flanges. The outlet flange 10 is provided with an outlet opening 10 'of approximately circular shape. Both the extreme zone of the outer helmet 2 and the extreme zone of the inner helmet 1 penetrate juxtaposed in the outlet opening 16 such that the outer helmet 2 penetrates more in the outlet opening 16 than the inner helmet 1. The helmet inner 1 and outer hull 2 are connected to the outlet flange 10 through a common welding seam 17 disposed on the inner surface of the opening of
exit 16.

The two central inlet flanges 5 and 6 are linked to each other through a junction bridge 18 that extends along the extension of the exhaust elbow between the input flanges 5 and 6. The input flanges 3 and 4, 4 and 5, 6 and 7, 7 and 8 located further out are not connected to each other.

The exhaust elbow is built in shape substantially symmetric with respect to a mirror plane 19 that passes through the center of said exhaust elbow along the opening Exit 16 and through junction bridge 18 (Figure 2). Therefore, the remaining structure of the exhaust elbow is represented only for half of said exhaust elbow, since the other half is specularly symmetric with respect to the first half.

The inner case is constituted substantially by a connecting pipe 20 that extends from the inlet opening 3 'to outlet opening 10', a pipe of junction 21 extending from the inlet opening 4 'to the outlet opening 10 ', and a connecting pipe 22 extending from the inlet opening 5 'to the outlet opening 10'. The junction pipe 20, which joins the outermost inlet flange 3 with the output flange 10, is here the longest of the three pipes of union, correspondingly shorter connecting pipes 21 and 22. The connecting pipes 20 and 21 run parallel in the area between the input flange 4 and the input flange 5 and meet forming a common tube that is configured as a collecting zone 24 in the area of the inlet flange 5. The collecting area 24 is constituted by a first semi-helmet 25 and a second semi-helmet 26. The first half-shell 25 then comprises the inlet opening 5 ' for the input flange 5. The first half-shell 25 and the second Semi-helmet 26 of the collecting zone 24 are connected to each other by middle of a longitudinal overlap welding seam 28. In the zone between the entrance flanges 4 and 5, in which the junction pipes 20 and 21 and they flow into the collecting zone 24, an overlap 29 is provided between the connecting pipes 20 and 21 and the collecting zone. Overlap 29 is set to a sliding seat between junction pipes 20 and 21 and the area collector 24, so that, under thermal expansion, it can have place a relative movement between the connecting pipes 20, 21 and the collecting zone 24.

The collecting zone 24 ends on the side of output in the form of a semicircular segment 30 and forms, together with the collecting area of the other symmetrical half of the exhaust elbow, a circular outlet opening 10 '.

On the extreme side in the direction of the longitudinal extension of the exhaust elbow is inserted into the pipe connection 20 a return pipe 31 of exhaust gas with a flange 32 located in it.

Around the represented arrangement of the inner hull 1, which is constituted by the connecting pipes 20 to 22, an outer helmet 2 is divided into two parts with a first outer halfcoat 33 and a second outer halfcoat 34. In the first outer half shell 33 the openings of inlet 3 'to 8' and half of the outlet opening 10 '. At second outer half-shell 34 is formed the other half of the exit opening 10 'and this half is connected to the first outer half-shell 33 by means of a welding seam of overlap 35 that runs all around it along the Exhaust elbow extension.

Both the different components of the helmet interior 1, for example the connecting pipes 20, 21 and 22, such as components of the outer hull 2, which presents the first half-helmet exterior 33 and the second outer half-shell 34, have been manufactured preferably as deep drawing pieces of sheet metal thin, preferably stainless steel sheet. The parts of the outer hull 1 have been made of sheet metal with a thickness of preferably 0.8 mm, having been manufactured preferably the components of the outer hull 2 based on a 1.5 mm thick sheet. Input flanges 3 to 8, the outlet flange 10 and exhaust gas return flange 32 have been made of material as a forged sheet with a wall thickness of preferably 8 mm. The air gap 13 between the inner helmet 1 and outer helmet 2 is comprised preferably between 4 and 6 mm. Since the inner hull 1 is provided with overlap 29 configured as a sliding seat to effect a thermal compensation of length, the helmet Interior 1 is not built in a gas tight manner. He inner hull 1 serves to conduct the gas along with its junction pipes 20, 21 and 22, which meet in the area collector 24, running the gas lines from the different combustion engine cylinders in very wide form separated from each other inside the inner hull 1 to achieve a favorable unstationary behavior of the combustion engine.

In a variant according to figure 8 the bridge of junction 18 between the inlet flange 5 and the inlet flange 6, made of a material with greater thermal expansion, it is provided of a longitudinal bore 36, whereby gases of Hot exhaust through junction bridge 18 to heat this bridge 18. During operation, the exhaust elbow shown is exposed to large temperature fluctuations from temperature ambient to the highest temperatures of the exhaust gases and expands in accordance with the heating produced by the hot exhaust gases. In a single piece exhaust elbow or single flow for a six-cylinder in-line engine dilations between hot and cold can reach up to 2.7 mm along the longitudinal extension of the exhaust elbow. Since the engine of combustion in which the exhaust elbow is fixed does not expand during operation as strongly as the exhaust elbow fixed to same, a relative movement between the flanges must be possible of inlet 3 to 8 of the exhaust elbow and the fixing surface in the motor, since, otherwise, the thermal stresses inside of the exhaust elbow can lead to plastic deformations and to the crack formation. The inventors have studied for it by an analysis of tensions of finite elements an elbow of Exhaust without connecting bridge 18 (Figure 9) and an exhaust elbow with junction bridge 18 (figure 10) made of a material with greater thermal expansion An exhaust elbow without connecting bridge 18 shows in this study according to figure 9 some areas of extreme tensions 37 in the central section of the exhaust elbow, which represent plastic dilations The central section of the exhaust elbow is subjected to a very high thermal solicitation, since in this area it find the outlet opening 10 '. The thermal expansion produced when the exhaust elbow is heated and the contraction of the central section in the form of a sliding force produced when cooled they have to be transmitted to the respective outermost inlet flanges 5, 4 and 3 and on the other side 6, 7 and 8 to avoid deformations plastic. In the exhaust gas elbow shown in Figure 10, which is provided with the connecting bridge 18 made of a material with greater thermal expansion, there are no stress zones extremes in the central section of the exhaust elbow, since the bridge of union contributes to dilation and also to contraction under the thermal load of the exhaust elbow. This way, you can build in one piece a relatively long exhaust elbow for an engine of six cylinders in line, but also for a four-engine cylinders in line, being able to group all the openings of 3 'to 8' inlet to produce a single flow to the opening of exit 10 '. Therefore, the exhaust elbow provided with the bridge junction 18 made of a material with greater thermal expansion is permanently stable despite a "shock effort thermal "and this with a reduced weight and a good effect of isolation.

Claims (7)

1. Exhaust elbow for driving exhaust gases from a combustion engine with more than three cylinders arranged in a row, comprising an outer helmet (2) that extends along of exhaust outlets of cylinders arranged in line; an inner hull (1) arranged inside the outer hull (2) to form an air gap insulation between the inner helmet (1) and the outer helmet (2), a common outlet opening (10 ') that is located on the exhaust side of the exhaust gas and that is practiced in a central section of the exhaust elbow, for each cylinder, a respective flange of inlet (3-8) located on the gas inlet side Exhaust, the inlet flanges being connected to each other (3-8) of the two central cylinders (5, 6) through of a connecting bridge (18), characterized in that the connecting bridge (18) is made of a material that has a thermal expansion greater than that of the material of the remaining components of the exhaust elbow. 2. Exhaust elbow according to claim 1, characterized in that a through hole (36) is provided between the flanges of the two central cylinders (5, 6) so that said joint bridge (18) is provided in the connecting bridge (18). ) can be heated by hot exhaust gases. 3. Exhaust elbow according to claim 1 or 2, characterized in that the connecting bridge (18) is provided with thermal insulation. 4. Exhaust elbow according to one of claims 1 to 3, characterized in that the inner hull (1) conducts the exhaust gases from the inlet openings (3'-8 ') formed in the inlet flanges (3-8) to the common outlet opening (10 '). 5. Exhaust elbow according to one of claims 1 to 4, characterized in that the inner hull (1) is formed by several pieces, the inner hull pieces (1) being joined in areas of great thermal expansion through a sliding seat (29). 6. Exhaust elbow according to one of claims 1 to 5, characterized in that the outlet opening (10 ') is formed in an outlet flange (10), and inlet hulls (2) are fixed inlet flanges ( 3-8) and the outlet flange (10), the outer shell (2) having the bearing function and being built in a gas-tight manner. 7. Exhaust elbow according to one of claims 1 to 6, characterized in that a return flange (32) is arranged on one end side of the exhaust elbow to derive exhaust gas.