DE102010018087A1 - Waste gas system for V-type six cylinder combustion engine, has inner and outer manifolds integrated into one another such that collection tube of outer manifold encloses collection tube of inner manifold under formation of air gap - Google Patents

Abstract

The system has inner and outer exhaust gas manifolds (12, 14) integrated into one another such that a collection tube (14a) of the outer exhaust gas manifold encloses a collection tube (12a) of the inner exhaust gas manifold under formation of an exhaust gas-carrying air gap. The collection tubes of the inner and outer exhaust gas manifolds are arranged in a counter flow that flows through diverting flanges (18, 20) and against opposite ends of the collection tubes. The collection tube of the outer exhaust gas manifold is provided with insulation or a heat insulating cover.

Description

The invention relates to an exhaust system for an internal combustion engine having a plurality of cylinders and a separate exhaust system, in particular for a register-charged internal combustion engine, according to the preamble of claim 1.

Such an exhaust system describes the EP 1 645 735 A1 in conjunction with an internal combustion engine with a register charge, in which the exhaust gases from the combustion chambers of the turbine of a first exhaust gas turbocharger and a higher load range via a first exhaust manifold and exhaust pipes in a lower load range of the internal combustion engine via a second, separate exhaust manifold and exhaust pipes of the turbine of a second exhaust gas turbocharger be supplied. The design and construction cost of two to be connected to the engine with each combustion chamber two separate exhaust ducts exhaust manifold is considerable, especially if the exhaust manifold for thermodynamic reasons and to reduce their heat dissipation should be isolated accordingly.

The object of the invention is to propose an exhaust system with separate exhaust gas discharge, which is structurally and manufacturing technology particularly favorable and has an effective thermal insulation at low internal material stresses.

This object is achieved by the features of claim 1. Advantageous and particularly expedient developments of the invention are the subject of the dependent claims.

According to the invention it is proposed that the exhaust manifolds are integrated into one another such that the manifold of the outer exhaust manifold encloses the manifold of the inner exhaust manifold to form an exhaust gas-carrying air gap. By virtue of this measure, preferably two exhaust manifolds require, in addition to the structural simplification, only a little more installation space than a single, air-gap-insulated exhaust manifold. Furthermore, the outer exhaust manifold substantially simultaneously forms the heat insulation of the inner exhaust manifold, so that a separate thermal insulation of the same can advantageously be omitted. During the Abgasbeaufschlagung only the inner exhaust manifold, the outer exhaust manifold is partly miterwärmt, which brings in addition to a favorable, uniform temperature load of the entire exhaust manifold additionally thermodynamic advantages in the switching of the exhaust gas flows on both exhaust manifold with it.

Preferably, it is further proposed for this purpose that the two manifolds of the exhaust manifold are flowed through in counterflow and that the outflow flanges are arranged at the mutually remote ends of the manifolds. Although theoretically a DC principle can be used with two adjacent outflow flanges, the preferred embodiment provides a simplified, further exhaust routing of the subsequent exhaust pipes and an even more uniform temperature distribution over the entire exhaust manifold.

Structurally and functionally particularly favorable, the manifolds of the two exhaust manifolds may be offset from each other by the offset of the separate exhaust passages in the internal combustion engine, wherein the inner manifold at the outlet from the outer manifold to the adjacent Abströmflansch by means of an outer tube section is air gap isolated.

Furthermore, the effective flow cross sections of the individual lines adjoining the exhaust gas ducts or the connecting flanges and the manifolds of the inner exhaust manifold may be designed to be smaller than the effective flow cross sections of the outer exhaust manifold. This leads in adaptation to a modified control logic of the internal combustion engine to a rapid heating of the inner exhaust manifold to achieve u. a. favorable measured values in the exhaust gas purification system of the internal combustion engine.

In terms of manufacturing technology, the two exhaust manifolds can preferably be produced by casting technology and / or their connecting flanges are combined to form a structurally robust construction to form a single connecting flange. Possibly. However, the two exhaust manifolds could also be formed by a built construction of several, welded together items.

In an exhaust system in which the exhaust gases of the internal combustion engine are discharged in a lower load range only via each combustion chamber an exhaust passage and in the higher load range via the second or both exhaust ports per combustion chamber, it is also proposed that in a particularly advantageous manner, the inner exhaust manifold to the in the lower load range with exhaust gas-charged exhaust ducts is connected and thus ensures a rapid onset of exhaust gas conditioning.

Finally, in an advantageous embodiment of the invention, the manifold of the outer exhaust manifold may be provided with a heat-insulating or cover to create an even more effective thermal insulation or at least shielding to the outside.

An embodiment of the invention is explained in more detail below with further details.

Show it:

1 two integrated exhaust manifold of an exhaust system for an internal combustion engine with separate exhaust gas discharge in a three-dimensional view of the common connection flange on the internal combustion engine,

2 the assembly after 1 in another, three-dimensional view with downwardly directed connection flange, and

3 the assembly according to the 1 and 2 in a longitudinal section along the line III-III of 2 ,

The 1 shows partially an exhaust system for an internal combustion engine with two to a unit 10 combined exhaust manifolds 12 . 14 , which are connected to the cylinder head of an internal combustion engine. The internal combustion engine can be, for example, a six-cylinder internal combustion engine in a V arrangement with three cylinders per cylinder bank.

The construction unit 10 is part of an exhaust system for an internal combustion engine with separate in two exhaust gas flows I and II exhaust discharge, wherein in a manner not shown (see EP 1 645 735 A1 ) are provided in the cylinder head of the internal combustion engine per combustion chamber two exhaust valves controlled via exhaust valves, to which the exhaust manifold 10 . 12 are connected and wherein the exhaust gases are then fed via separate exhaust pipes two turbines of exhaust gas turbochargers (not shown).

The exhaust gas flow I or the exhaust manifold 12 is applied separately in the lower load range of the internal combustion engine, while in the higher load range, the exhaust gas flow II is switched on. The control of the exhaust gas flows I and II can be done via the function of the exhaust valves or arranged in the separate exhaust valves flapper valves.

The to the unit 10 combined exhaust manifold 12 . 14 each consist of a manifold 12a . 14a and three individual lines 12b . 14b in the headers 12a . 14a open out.

The single lines 12b . 14b run in a common connection flange 16 a, via which they are connected to the exhaust ducts, not shown, of the internal combustion engine.

At the ends of the headers 12a . 14a are opposing outflow flanges 18 . 20 molded, which are gas-tight connected to the subsequent exhaust pipes. The exhaust manifold 12 . 14 or their headers 12a . 14a are flowed through in countercurrent flow.

The manifold 12a (see. 3 ) of the inner exhaust manifold 12 runs while leaving a sufficient flow cross-section within the outer manifold 14a the outer exhaust manifold 14 , The outer manifold 14a thus forms an air gap insulation for the inner manifold 12a or substantially for the inner exhaust manifold 12 ,

The flow cross sections of the individual lines 12b and the manifold 12a are like in particular from the 3 can be seen smaller than the flow cross sections of the individual lines 14b and the manifold 14a the outer exhaust manifold 14 ,

Due to the structurally given offset of the separate exhaust ducts of the internal combustion engine per combustion chamber are also the two exhaust manifolds 12 . 14 offset in accordance with each other in the axial direction.

So that on the drawing 3 right single line 12b of the inner exhaust manifold 12 and the subsequent section of the manifold 12a up to the outlet flange 18 are also air gap isolated, is to the manifold 14a the outer exhaust manifold 14 a coaxial, approximately equal cross-section exhibiting pipe section 22 molded, the manifold 12a up to the outlet flange 18 encloses. The pipe section 22 is fluid dynamics but irrelevant, the actual manifold 14a starts in the direction of flow as seen from the 2 and 3 can be seen in the first single line 14b (left side of the drawings).

The construction unit 10 from the two exhaust manifolds 12 . 14 is by casting z. B. produced in chill casting with lost core of high-alloy cast iron. For structural reasons and strength reasons, this is a continuous connection flange 16 used in the single lines 12b . 14b both exhaust manifolds 12 . 14 run in and connected via appropriate fastening means with the flange of the cylinder head of the internal combustion engine with the interposition of a temperature-resistant gasket gas-tight.

In a manner not shown may also be the outer manifold 14a the exhaust manifold 14 be thermally insulated. This can be done by means of another, an air gap enclosing tube or through an insulating sheathing or possibly be accomplished by a locally provided shielding.

In an internal combustion engine not yet having a lower operating temperature and / or in the lower load range of the internal combustion engine, only the inner exhaust manifold is used 12 subjected to the exhaust gas flow I. In this case, the outer exhaust manifold is used 14 , which is not yet traversed by exhaust gas, as an air gap insulating member and causes rapid heating of the inner exhaust manifold 12 with low thermodynamic losses, so that downstream devices of the exhaust system such as a turbine of the first exhaust gas turbocharger and / or an exhaust gas purification device can respond better.

At the same time, with the exhaust gas flow I and the outer exhaust manifold at a longer operating state 14 heated, so that when it is connected via the exhaust gas flood II no sudden thermodynamic losses occur and operational thermal stresses are largely avoided.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 1645735 A1 [0002, 0018]

Claims (7)

Exhaust system for an internal combustion engine having a plurality of cylinders and a separate exhaust discharge via each combustion chamber at least two exhaust ducts in connecting flanges of several, preferably two exhaust manifolds, of which the exhaust gas is passed via a respective manifold and a Abströmflansch to the further exhaust system, characterized in that the exhaust manifold ( 12 . 14 ) are integrated with each other in such a way that the collecting pipe ( 14a ) of the outer exhaust manifold ( 14 ) the collecting pipe ( 12a ) of the inner exhaust manifold ( 12 ) encloses to form an exhaust gas-carrying air gap. Exhaust system according to claim 1, characterized in that the two header pipes ( 12a . 14a ) the exhaust manifold ( 12 . 14 ) are flowed through in counterflow and that the outflow flanges ( 18 . 20 ) at the opposite ends of the headers ( 12a . 14a ) are arranged. Exhaust system according to claim 1 and 2, characterized in that the collecting pipes ( 12a . 14a ) of the two exhaust manifolds ( 12 . 14 ) are offset by the offset of each of the separate exhaust passages in the internal combustion engine to each other, wherein the inner manifold ( 12a ) at the exit from the outer collecting tube ( 14a ) right up to the outlet flange ( 18 ) by means of an outer pipe section ( 22 ) is air gap isolated. Exhaust system according to one of the preceding claims, characterized in that the effective flow cross sections of the exhaust ducts or the connecting flanges ( 16 ) subsequent individual lines ( 12b ) and the manifold ( 12a ) of the inner exhaust manifold ( 12 ) smaller than the effective flow cross sections of the outer exhaust manifold ( 14 ) are designed. Exhaust system according to one of the preceding claims, characterized in that the two exhaust manifolds ( 12 . 14 ) are manufactured by casting and / or that their connection flanges to a single flange ( 16 ) are summarized. Exhaust system according to one of the preceding claims, characterized in that in the event that the exhaust gases of the internal combustion engine are discharged in a lower load range only via each combustion chamber an exhaust passage and in the higher load range via both exhaust channels per combustion chamber, the inner exhaust manifold ( 12 ) is connected to the also in the lower load range with exhaust gas charged exhaust gas channels (exhaust gas flow I). Exhaust system according to one of the preceding claims, characterized in that the collecting pipe ( 14a ) of the outer exhaust manifold ( 14 ) is provided with a heat insulating insulation or cover.

Images