DE102011086778A1 - Exhaust gas-turbo-loaded combustion engine i.e. diesel engine, has exhaust gas catalyst integrated in bypass strand behind high pressure turbine of supercharger, and bypass pipe in parallel connection to high pressure turbine - Google Patents

Abstract

The engine has an exhaust line (21) comprising an exhaust gas catalyst i.e. oxidation catalyst (15) such as pre-turbo catalyst, in a series arrangement with a high pressure turbine (14) and a low-pressure turbine (16) of first and second superchargers. A bypass pipe (22) is in a parallel connection to the high pressure turbine of the first supercharger. The exhaust gas catalyst is integrated in a bypass strand behind the high pressure turbine to a bypass flap (12), where the bypass strand and the bypass flap are integrated in a common bypass housing (13) adjacent to each other.

Description

The invention relates to an internal combustion engine with an exhaust line and two-stage turbocharging, wherein the exhaust system comprises two turbines of a first and a second exhaust gas turbocharger and at least one exhaust gas catalyst, in particular an oxidation catalyst in series and a bypass line in parallel to the high-pressure turbine of the first exhaust gas turbocharger.

Such an internal combustion engine is from the WO 2004/097195 A1 known. This internal combustion engine has a two-stage turbocharging, wherein an oxidation catalytic converter is inserted into the connecting line between the high-pressure turbine of the first turbocharger and the low-pressure turbine of the second turbocharger. In order to install the oxidation catalyst in this connection line, a minimum sizing of this connection line is required in order to accommodate the oxidation catalyst can. In addition, the connecting line for receiving the oxidation catalyst must be formed, for example, be formed with corresponding flanges for mounting the built-in a separate housing catalyst.

The invention has for its object to provide a exhaust-gas-charged internal combustion engine with catalytic converter ready, which is improved in terms of the Verbaus the catalytic converter.

Disclosure of the invention

Advantages of the invention

This object is achieved in that the exhaust gas catalyst, in particular an oxidation catalyst, is integrated behind the high-pressure turbine of the first exhaust gas turbocharger in a bypass line of a turbine bypass valve, and that the bypass line and the turbine bypass valve are integrated in a common bypass housing.

In the context of the invention, the catalytic converter can also be a 3-way catalytic converter for a gasoline engine instead of the oxidation catalytic converter. Due to this configuration and integration in the common bypass housing no additional route or connection line to the high-pressure turbine as installation or installation space for the oxidation catalyst is necessary. As a result, the influence on the flow and thus the expected pressure losses is minimal. In the integration of the oxidation catalyst, which is otherwise designed as a so-called PTC (Pre Turbo Catalyst) in the bypass housing takes place no enlargement of the wall surface and thus no increase in wall heat losses. The bypass housing is in any case heated during operation of the internal combustion engine, wherein the weight and thus the heat capacity of the catalyst material are negligible. In addition, no additional space is needed; the system remains compact. A general advantage of a system with a PTC over a system without PTC is the accelerated readiness of the oxidation catalyst. As a result, HC / CO emissions are converted earlier in a cold start of the corresponding equipped engine.

As a result of the configuration according to the invention, a significantly better response of the high-pressure compressor of the first exhaust gas turbocharger is achieved in comparison with a system which has an oxidation catalytic converter in front of the high-pressure turbine, which in turn decisively determines the dynamics of the air system. Compared to a system without oxidation catalyst, there are no changes in the response. The supercharging pressure build-up between the system without and that with an oxidation catalyst between the high pressure turbine of the first exhaust gas turbocharger and the low pressure turbine of the second turbocharger is almost identical. The temperature loss is significantly lower compared to an arrangement of the oxidation catalyst, for example, in front of the high-pressure turbine of the first exhaust gas turbocharger. In addition, the temperature loss of minor importance, since the main work is done in a load jump anyway from the high pressure supercharger of the second exhaust gas turbocharger.

The better response of the high-pressure loader with load jumps leads to an excess of air in the combustion. This results in particular in less soot and HC / CO emissions in the dynamic phases.

The arrangement of the oxidation catalyst in the bypass line behind the high-pressure turbine of the first exhaust gas turbocharger, the very high exhaust gas temperatures (up to 800 ° C) are avoided in full-load operating points of the internal combustion engine, because in these operating points, the bypass valve is open and the exhaust gas does not flow through the oxidation catalyst. The exhaust backpressure is reduced, thus improving the efficiency of the internal combustion engine. In addition, the likelihood of premature aging of the oxidation catalyst is reduced.

Further advantageous embodiments of the invention can be found in the drawing description, in which an illustrated in the figures embodiment of the invention is described in more detail:

Brief description of the drawings

Show it:

1 a block diagram of an internal combustion engine with two-stage turbocharging and inventively built oxidation catalyst and

2 an end view of a bypass housing of the first exhaust gas turbocharger with integrated oxidation catalyst.

Embodiment of the invention

The block diagram according to 1 shows a three-cylinder internal combustion engine nine with a fresh air line 20 and an exhaust system 21 , The fresh air line 20 gets fresh air 1 via an air filter 2 and a hot film air mass meter 3 , continue via a low-pressure compressor 4 a second exhaust gas turbocharger and a high pressure compressor 6 a first exhaust gas turbocharger, further via a charge air cooler 7 and a throttle 8th fed. The high pressure compressor 6 is via a compressor bypass 5 bypassed.

The fresh air supplied together with a fuel, in particular diesel fuel, in the combustion chambers of the internal combustion engine 1 leaves after combustion the internal combustion engine nine and the exhaust system 21 as exhaust 19 , A portion of the burned exhaust gas is passed through an exhaust gas recirculation line into which an exhaust gas recirculation cooler 10 and an exhaust gas recirculation valve 11 are installed to control the amount of recirculated exhaust gas, in the fresh air line 20 directly in front of the inlet to the internal combustion engine nine recycled. The remaining exhaust gas flow becomes a high-pressure turbine 14 supplied to the first exhaust gas turbocharger and passes behind the high-pressure turbine 14 to an exhaust gas catalyst in the form of an oxidation catalyst 15 , The oxidation catalyst 15 is in a bypass housing 13 the high pressure turbine 14 installed the first exhaust gas turbocharger, the exact installation of the 2 can be seen. The bypass housing 13 has a bypass line 22 with a bypass flap 12 on top of that the high pressure turbine 14 is bypassable. Behind the oxidation catalyst 15 is in the exhaust system 21 a low pressure turbine 16 installed with variable geometry, which is part of the second exhaust gas turbocharger. This low pressure turbine 16 close a diesel oxidation catalyst 17 and a particle filter 18 before, the purified exhaust gas 19 gets into the environment.

2 shows a view of the bypass housing 13 , being in the upper part of the bypass housing 13 the bypass line 22 with the bypass flap 12 is arranged, while in the lower part of the flow outlet, the high-pressure turbine 14 is arranged. In this flow outlet is the oxidation catalyst 15 integrated. Is the bypass flap 12 closed, which takes place especially at low speeds and loads of the internal combustion engine, in which the HC / CO emissions of the engine is relevant for the emission, the entire exhaust gas mass flow flows (except that in the fresh air line 20 recirculated exhaust gas) via the high-pressure turbine 14 and then through the into the bypass housing 13 integrated oxidation catalyst 15 , With open bypass flap 12 the exhaust gas flows 19 through the then released upper cross section of the bypass line 22 directly on the low-pressure turbine 16 ,

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

• WO 2004/097195 A1 [0002]

Claims (4)

Internal combustion engine with an exhaust gas line ( 21 ) and with two-stage turbocharging, wherein the exhaust gas line ( 21 ) two turbines of a first and a second exhaust gas turbocharger and at least one exhaust gas catalyst, in particular an oxidation catalyst ( 15 ) in series connection and a bypass line ( 22 ) in parallel with the high-pressure turbine ( 14 ) of the first exhaust gas turbocharger, characterized in that the exhaust gas catalytic converter ( 15 ) behind the high-pressure turbine ( 14 ) of the first exhaust gas turbocharger in a bypass line to a bypass flap ( 12 ) and that the bypass line and the bypass flap ( 12 ) in a common bypass housing ( 13 ) are integrated. Internal combustion engine ( nine ) according to claim 1, characterized in that the bypass strand and the bypass flap ( 12 ) juxtaposed in the bypass housing ( 13 ) are arranged. Internal combustion engine ( nine ) according to one of the preceding claims, characterized in that the bypass housing ( 13 ) is connected to the turbine housing of the first exhaust gas turbocharger, in particular united. Internal combustion engine ( nine ) according to one of the preceding claims, characterized in that the catalytic converter ( 15 ) caseless in the bypass housing ( 13 ) is used.

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