DE19938359A1 - Exhaust manifold for multi-cylinder engine with secondary air input, in which secondary air is introduced into exhaust gas via several venturi sectors - Google Patents

Abstract

The exhaust manifold (1) includes a flange (2) and several exhaust tubes (3). The secondary air is introduced into the exhaust gas via a number of venturi sectors (4) to improve the flow and reduce losses. The venturi sectors may be fitted in the flange, forming a projection (10), which at least partly projects into the exhaust tube.

Description

The present invention relates to an exhaust manifold for a Mehrzy Lindy internal combustion engine with secondary air supply, comprising a Flange and several exhaust pipes.

Secondary air is supplied in accordance with documents DE 197 35 061 A1 and DE 298 18 763 U1, by ge in one of several layers formed flange of the exhaust manifold secondary air lines are integrated, which are in open connection with the exhaust pipes. With this State of the art is very much based on the production of the multilayer flange agile and leaks often occur.

In addition, a flange for is from the document DE 197 52 551 A1 a multi-flow exhaust system of motor vehicles known as the one cast casting with the inlet openings for secondary air and channels open to the exhaust gas passage openings are formed. The Connection of these channels to the exhaust gas passage openings is there by means of inserted sleeves closed, the sleeves with the upper and Un Close the bottom of the flange and connect the exhaust pipe re serve.

The above statements are in fluidic Hin However, the view is extremely unfavorable, since Se secondary air in the exhaust gas unacceptably high flow and pulsation lusts occur.

Against this background, it is an object of the present invention, one to design an improved exhaust manifold that has a particularly stream low-cost and therefore low-loss supply of secondary air in the Exhaust gas allows.  

This task is solved by the supply of secondary air into the Exhaust gas is made over a number of venturi sections. In this way can take advantage of such venturi sections or venturi nozzles optimal secondary air supply can be used. Besides, it is one Exhaust manifolds are also inexpensive to manufacture because of the venturi sections manufactured separately and then integrated into the exhaust manifold can.

The venturi sections are inserted into the flange so that they are on both Form an overhang on the sides, so the upstream overhang can Position the exhaust manifold in relation to the engine block and can the downstream protrusion for positioning the exhaust pipes on Serve flange.

The projecting Venturi sections protrude at least partially into the exhaust pipes into it is a particularly favorable seal of the same possible.

The flange, the exhaust pipes and the venturi sections are expedient Connected to each other via a common weld. Because by egg ne common weld is provided on the downstream side passage from the flange to the exhaust pipes or to the venturi sections runs, all three elements can last with only a small weld length be connected with each other.

The Venturi sections are each advantageous one cylinder of the Brenn assigned to the engine, thus by fine-tuning the sections an equal distribution of the recirculated secondary air to the individual Zy linder the internal combustion engine is possible.

The Venturi sections are particularly advantageous in terms of the firing order successive cylinders of the internal combustion engine via separate Se secondary air lines supplied secondary air. In this way, a so-called crosstalk between the exhaust pipes of the individual cylinders be avoided since the time intervals between the exhaust strokes the cylinder supplied by one and the same secondary air line is enlarged are.  

The secondary air lines can also in the present invention be integrated into the flange. Alternatively, however, it would also be conceivable that se Parate secondary air lines are provided, which are largely parallel to the flange and then in another way with the Venturi Related sections.

The venturi sections preferably have an annular space with an inward NEN directed curvature, a number in the area of the curvature of distribution openings arranged in a distributed manner. Thereby can the supplied secondary air in spite of the exhaust pipe side supplied secondary air lines approximately evenly distributed to Ab Gas are added so that a homogeneous mixing of exhaust gas and secondary air is effected.

The present invention will be described with reference to the following Drawing figures explained in more detail. Show it:

Figure 1 is a partial perspective view of the exhaust manifold.

FIG. 2 is a sectional view along the line II-II 'from FIG. 1;

Fig. 3 is a sectional view taken along the line III-III 'of Fig. 1; and

Fig. 4 shows a section along the line IV-IV 'in FIG. 1.

The exhaust manifold 1 for a four-cylinder internal combustion engine with därluftzufuhr comprises a flange 2 , four exhaust pipes 3 and four Venturi sections 4 , but in Fig. 1, however, only a part of the exhaust manifold 1 with two Venturi sections 4 is shown. The exhaust pipes 3 are not shown in FIG. 1 for reasons of clarity, while they are contained in FIGS. 2, 3 and 4.

The flange 2 is a one-piece casting which is fastened to a cylinder head (not shown) by means of a number of screws 6 or stud bolts and nuts surrounding the flange openings 5 . The flange 2 ent has a thickening 7 along one of its long sides, into which two separate secondary air lines 8 , 8 'are integrated. From the secondary air lines 8 , 8 'go out connecting lines 9 which extend to the flange openings 5 .

In the flange openings 5 , the prefabricated Venturi sections 4 are set, forming an overhang 10 , 10 'on both sides of the flange 2 . The downstream protrusion 10 is preferably larger than the upstream protrusion 10 '. The venturi sections 4 are of two shells and have an annular space 12 between their two shells 11 , 11 ', which has on its outer shell 11 a connection opening 13 which is connected to one of the connecting lines 9 and which is on its inner shell 11 ' has a number of supply openings 14 for secondary air. The feed openings 14 are arranged at the same distance from each other, but have different cross sections depending on their position from the connection opening 13 .

On the downstream protrusions 10 of the Venturi sections 4 , the ge curved exhaust pipes 3 of the individual cylinders of the internal combustion engine are set on, which merge further downstream.

The flange 2 , the exhaust pipes 3 and the venturi sections 4 are connected by means of a common weld seam 15 , which is arranged at the transition from the flange 2 to the downstream overhang 10 of the venturi section 4 and at the same time also the upstream end of the gas pipe 3 surrounds. At the opposite transition from the flange 2 to the upstream projection 10 'of the venturi section 4 , a further weld 15 ' should be arranged to increase the rigidity.

To avoid so-called crosstalks, that is, pulsations between the exhaust gases of the individual exhaust pipes 3 , which can be caused by the superposition of the exhaust gas from successive exhaust strokes of the internal combustion engine, the Venturi sections 4 of sequential cylinders in the ignition sequence are here I, III, IV and II - for example, the cylinders II and I are supplied with secondary air via separate secondary air lines 8 , 8 '. This can be clearly seen from FIGS . 3 and 4, which show the sectional views associated with the cylinders I and II.

Claims (8)

1. exhaust manifold for a multi-cylinder internal combustion engine with secondary air supply, comprising a flange and several exhaust pipes, characterized in that the supply of secondary air into the exhaust gas via a number of venturi sections ( 4 ). 2. Exhaust manifold according to claim 1, characterized in that the venturi sections ( 4 ) are inserted into the flange ( 2 ) and form an overhang ( 10 , 10 ') on the sides. 3. Exhaust manifold according to claim 1 or 2, characterized in that the projecting venturi sections ( 4 ) at least partially protrude into the exhaust pipes ( 3 ). 4. Exhaust manifold according to one of claims 1 to 3, characterized in that the flange ( 2 ), the exhaust pipes ( 3 ) and the Venturi sections ( 4 ) are connected to one another via a common weld seam ( 15 ). 5. Exhaust manifold according to one of claims 1 to 4, characterized in that the venturi sections ( 4 ) are each assigned to a cylinder (I, II, III, IV) of the internal combustion engine. 6. Exhaust manifold according to one of claims 1 to 5, characterized in that the venturi sections ( 4 ) in the ignition sequence (I, III, IV, II) successive cylinders of the internal combustion engine via separate secondary air lines ( 8 , 8 ') Secondary air is supplied. 7. Exhaust manifold according to one of claims 1 to 6, characterized in that the secondary air lines ( 8 , 8 ') are integrated in a thickened portion ( 7 ) of the flange ( 2 ). 8. Exhaust manifold according to one of claims 1 to 7, characterized in that the venturi sections ( 4 ) have an annular space ( 12 ) with an inward curvature, wherein in the area of the arching a number of distribution openings ( 14 ) are provided, the feed openings (14) on the kundärluftleitungen the Se (8, 8 ') side facing a smaller diameter have than on that of the secondary air lines (8, 8') from facing side.