DE4228187A1 - IC engine exhaust gas high performance header - has header pipes hydrostatically deformed, with transition-free, arcuated course - Google Patents

Abstract

The header has a primary flange at the cylinder side, and a secondary one downstream in the exhaust gas flow direction, between which are fitted header pipes (13-16) of different lengths. The pipe end regions are secured in the flange retaining apertures, with the secondary flange contg. smaller number of apertures. The header pipes are hydrostatically deformed and have transition-free, arcuated course. The end region (25) of at least one pipe, (13,15) open into the secondary flange outside of an end region (26) of another header pipe (14,16). ADVANTAGE - Increased service life.

Description

The invention relates to an exhaust manifold for Internal combustion engines with a cylinder-side primary flange and one with respect to the flow direction of the exhaust gases downstream secondary flange, between which Krüm merrohre of different lengths are arranged, the end areas are fixed in receiving openings of the flanges where has fewer receiving openings in the secondary flange than the primary flange.

The well-known exhaust manifold has manifold pipes of different lengths, always two in one Level merged like a piece of pants and in one Receiving opening of a secondary flange are welded. To form this piece of trousers, the manifold pipes in the Proximity of the secondary flange on the sides facing each other flattened end-to-end and in the area of the An position together to form a midrib welds. This results in a common end area of the two merged manifold pipes, the inside and outside  is essentially circular, the Middle rib, however, extends into the end area. In Be For this reason, the middle rib is richly divided between the secondary flange and the common wall of the Manifold pipes available.

In addition, the manifold pipes are made by bending been put. However, no bending can be done create manifold pipes, so that the manifold pipes according State of the art always certain deviations from the circle have shape.

If now those made by bending and each with a common end portion forming manifold pipes the secondary flange on the one pointing away from the elbow pipes Side of the flange are welded, then result not only in the area of the midrib, but due to the Deviations from the circular shape also in other areas Chen air gaps between the outer peripheral surface of the common same end area of the manifold pipes and the peripheral surface the receiving openings of the secondary flange. During loading The engine is now driven by the well-known exhaust manifold heated up to a temperature of approx. 700 ° C. When heating of the exhaust pipe manifold of different lengths However, there is a different amount in terms of amount expansion of the individual manifold pipes. Because the distance of the both flanges to each other, however, through the shortest elbow pipe is determined, he step in the longer elbow pipes increased tensions that are not due to a sufficient degree Bending deformation of the manifold pipes can be reduced. This  then often leads to cracks on the flange side Welded joints.

In addition, there are known exhaust gas compartments additional elbows especially in the cooling phase Problems. Basically, the much thinner cool Exhaust pipes turn off much faster than the two right relatively thick flanges. Because between the common end area the manifold and the peripheral surface of the receiving opening however, an "insulating" air gap at least in part the end area of the elbow pipes also cools faster than the flange receiving the end area. There through it occurs within the welded joint of additional thermal stresses that damage it and can even lead to tearing.

Ultimately, those manufactured by means of bending Elbow pipes always have different wall thicknesses, which means an irregulari when heating the exhaust manifold voltage curve within the individual manifold tubes gives.

As a result, all of this means that the lifespan the known exhaust manifold is relatively low.

The object of the invention is therefore an exhaust gas fan to create manifolds for internal combustion engines, which is an essential has a longer lifespan.  

The invention solves this problem essentially through that the manifold tubes are hydrostatically formed so like an essentially seamless transition have and that the end portion of at least one elbow merrohres outside the secondary flange-side end area another manifold pipe opens into the same.

The exhaust manifold according to the invention has the front part that by the essentially transition-free arched against the course of the individual elbow pipes in heat-related Changes in length are possible due to bending deformation for the flange-side weld connections dangerous pull and Reduce pressure loads.

In addition, due to the hydrostatic deformation of the pipes ensures that there are no deviations from the desired cross section comes and that the wall thickness in the we is approximately the same at every point. Due to the constant cross sections of the manifold pipes and through that Merge two elbow pipes outside the end the dimensional accuracy of the in the receiving opening arranged common end area significantly improved who the. Therefore, unlike the prior art, it does not to form air gaps between the end region of a Manifold and the peripheral surface of a receiving opening, so that the heat flow is not hindered and is approximately parallel cooling of the end area and flange results.  

Furthermore, the constant wall thickness leads to one uniform stress distribution within the wall of the individual manifold pipes.

Ultimately, the production of the elbow pipes allows using the hydroforming process to form the tubes reduced by at least 25% compared to the prior art Wall thickness. This has the advantage of a significant reduction the so-called "thermal mass" of the elbow, whereby the length of warm-up when operating a catalyst phase can be reduced.

All of these features essential to the invention as a result, the new exhaust manifold, in particular also the welded joints, a significantly longer life have duration.

The exhaust manifold according to the invention can about it in addition also manifold pipes of different, seamless have changing radii, cross sections and / or circumferences.

A particularly advantageous embodiment of the Erfin dung also consists of elbow pipes, one in the essential oval, flexible cross-section point. This advantageously leads to the fact that due to the different length changes in the amount causing tensile and compressive stresses, especially in loading range of the flange-side welded connections of the exhaust gas exhaust manifold, dismantled in a material-harmless manner,  by extending the single manifold pipe along the short axis of the oval cross section bends.

Further advantages of the invention result from the following subclaims and the description of a Embodiment. Show it:

Fig. 1 is a schematic view of a motor disposed exhaust MIVEC-header,

Fig. 2 is a plan view of the exhaust manifold in accordance with the viewing arrow II in Fig. 1,

Fig. 3 is a view of the exhaust MIVEC-header according to the viewing arrow III in Fig. 2,

Fig. 4 is a side view of the exhaust-MIVEC-header in accordance with the viewing arrow IV in Fig. 2,

Fig. 5 is a side view of the exhaust-MIVEC-header according to the viewing arrow V in Fig. 2,

Fig. 6 shows a cross section through a manifold according to section line VI-VI in Fig. 5 and

Fig. 7 shows a cross section through a manifold according to section line VII-VII in Fig. 5 and

Fig. 8 is a cross-section through a header pipe according to the section line VIII-VIII in Fig. 5.

In the drawings, the exhaust manifold is generally designated by reference number 10 .

The exhaust manifold 10 is suspended over a primary flange 11 with an elastic, ie with respect to its longitudinal axis x pendulum rotatably mounted motor 12 angeord net. The exhaust manifold 10 consists of manifold tubes 13 , 14 , 15 and 16 of different lengths, each of which has circular end regions 26 on both sides (see FIG. 6). Each of the elbow pipe 13 , 14 , 15 and 16 is welded on one side in receiving openings 17 of the primary flange 11 angeord net.

In addition, the exhaust manifold 10 has a secondary flange 18 with two receiving openings 19 on the so-called "hot side". In the receiving openings 19 of the secondary flange 18 , the elbow pipes 14 and 16 with the other end region 26 are welded firmly. In contrast, the manifold pipes 13 and 15 open with their secondary-side end regions 26 , which are designated in FIG. 2 with 29 , in the area of neckings 20 , 21 into the manifold pipe 16 and the manifold pipe 14, respectively. While the end regions 26 of the elbow pipes 14 and 16 are each connected to the flanges 11 and 18 by means of a weld seam 27 (see FIG. 3), the end regions 29 of the elbow pipes 13 and 15 are connected to the flanges 20 , by means of a further weld seam 28 . 21 firmly arranged.

Primary flange 11 and secondary flange 18 have white openings 22 for bolts, not shown, with which the exhaust manifold 10 on the one hand on the cooled motor 12 (cold side) and on the other hand can be connected to a flange 23 of two front pipes 24 (see FIG . 1).

While the flanges 11 and 18 are produced in the present case by stamping processes, the special shape of the individual elbow pipes 13 to 16 is created by the hydroforming process. In this process, metal pipes made of heat-resistant, austinitic stainless steel of smaller diameter and greater wall thickness are roughly pre-shaped by mechanical shaping so that the preform of the elbow pipe can already be recognized. This intermediate product is then inserted into a die, the engraving of which can already determine the final shape of the elbow pipe, although several intermediate stages may also be necessary to produce the final elbow pipe. The intermediate tube product received by the die is then acted upon by a hydraulic hydraulic fluid with a high hydrostatic internal pressure, thereby widened and nestled against the engraving, so that the manifold tube is essentially finished. It is important that it is possible with the help of the hydroforming process to produce manifold pipes in series, which have approximately identical dimensions and are easily plug-in.

To produce the ver provided with a neck 20 or 21 manifold pipes 14 or 16 , the neck are essentially also created by widening the manifold pipe at the desired location by means of a hydraulic Druckflüs liquid. The still closed neck is then "cut open" so that there is an opening 25 in each of the elbow pipes 14 and 16 . The outer diameter of the neck 21 , 22 and the inner diameter of the opening 25 are dimensioned such that the end regions 26 of the elbow pipes 13 and 15 either up on the neck 20 , 21 or inserted into the opening 25 and can be welded there .

The manifold pipes 13 to 16 can be dimensioned with the help of the hydroforming process so that they have constantly changing radii of curvature, cross sections (see FIGS. 6, 7 and 8) and / or circumferences over the longitudinal course. For example, all elbow pipes 13 to 16 are curved in each area, the changes in curvature being smooth. In addition, the cross section of the manifold tubes 13 to 16 is at least outside the ver welded in the flanges 11 and 18 end regions 26 more or less oval. The oval, deflection-favorable cross-section (see FIGS . 7 and 8) enables each individual manifold pipe 13 to 16 , the different length increases occurring when the exhaust manifold 10 is heated to be caught by bending, without causing greater tensile or compressive loads e.g. B. could damage the weld 27 between the manifold pipes 13 to 16 and the individual flanges 11 and 18 . It is important that the oval cross-section in the coordinate system is oriented so that the short cross-sectional axis of the oval tube runs in the bending direction, so that the tube opposes the bending only a small section modulus.

Basically, the distance between the flanges 11 and 18 to each other in particular by the shortest manifold tube be true. This shortest manifold tube naturally also has the smallest increase in length when the exhaust manifold 10 is heated. The difference in length between the shortest elbow pipe and the longer elbow pipe initially leads to a build-up of tension (compression) in the three longer elbow pipes, which, due to their flexible cross-section and the continuously curved shape, can reduce this tension by bending deformation. On the other hand, the shortest tube is generally stretched in principle, whereby the likewise curved course and favorable cross-section enable this stretching.

Claims (11)

1. Exhaust manifold for internal combustion engines with a cylinder-side primary flange and a secondary flange downstream with respect to the flow direction of the exhaust gases, between which manifold pipes of different lengths are arranged, the end regions of which are fastened in receiving openings of the flanges, the secondary flange having fewer receiving openings than that Primary flange, characterized in that the manifold tubes ( 13 , 14 , 15 , 16 ) are hydrostatically formed and have a substantially transition-free arcuate course and that the end region ( 29 ) of at least one manifold tube ( 13 , 15 ) outside the end region on the secondary flange side ( 26 ) another manifold pipe ( 14 , 16 ) opens into the same. 2. Exhaust manifold according to claim 1, characterized in that the manifold pipes ( 13 , 14 , 15 , 16 ) have different, seamlessly changing radii. 3. exhaust manifold according to claim 1, characterized in that the manifold pipes ( 13 , 14 , 15 , 16 ) have different union, seamlessly changing cross-sections and / or circumferences. 4. exhaust manifold according to claim 1, characterized in that the manifold tubes ( 13 , 14 , 15 , 16 ) in wesentli Chen an oval cross-section favorable to bending aufwei sen. 5. exhaust manifold according to claim 1 to 4, characterized in that a manifold pipe ( 14 , 16 ) has at least one neck ( 21 , 20 ) on which the end region ( 29 ) at least one other manifold pipe ( 15 , 13 ) be gas-tight is increasing. 6. exhaust manifold according to claim 5, characterized in that a manifold pipe ( 14 , 16 ) has two necklines ( 21 , 20 ) on which the end regions ( 29 ) of two manifold pipes ( 15 , 13 ) are arranged. 7. exhaust manifold according to claim 5, characterized in that the neckings ( 21 , 20 ) are arranged opposite one another on a manifold pipe ( 14 , 16 ). 8. Exhaust manifold according to one of claims 5 to 7, characterized in that the end region ( 29 ) of a manifold tube ( 15 , 13 ) in the neckings ( 21 , 20 ) of the other Ren manifold tube ( 14 , 16 ) insertable and there is weldable. 9. exhaust manifold according to one of claims 5 to 7, characterized in that the end region ( 29 ) of a manifold pipe ( 15 , 13 ) on the neckings ( 21 , 20 ) of the other on the manifold pipe ( 14 , 16 ) can be pushed on and there ver is weldable. 10. Exhaust manifold according to one of the preceding claims, characterized in that the manifold tubes ( 13 , 14 , 15 , 16 ) have a substantially constant wall thickness. 11. exhaust manifold according to one of the preceding claims, characterized in that two of the manifold pipes ( 13 , 14 , 15 , 16 ) open into one another via a piece of trousers.