DE102005056423B4 - Exhaust system in a commercial vehicle - Google Patents

Abstract

Exhaust system in a commercial vehicle with an internal combustion engine with V-shaped arranged cylinder banks, wherein the exhaust ducts each a cylinder bank (2.1, 2.2) into a common exhaust manifold (4.1, 4.2) open and the internal combustion engine (1), together with a to the internal combustion engine (1 ) flanged gear (16), between two longitudinal members (15.1, 15.2) of a chassis frame of a commercial vehicle are arranged so that the exhaust manifolds (4.1, 4.2) above the longitudinal beams (15.1, 15.2) extend and wherein a below the longitudinal beams (15.1, 15.2 ) is provided, which comprises at least one hydrolysis catalytic converter (10) and downstream of said one SCR catalytic converter (14), characterized in that each exhaust gas collector pipe (4.1, 4.2) is connected at its end to the inlet of at least one turbine (5.1, 5.2) of at least one exhaust gas turbocharger (6.1, 6.2) is connected, the turbine (5.1, 5.2) downstream of each an exhaust pipe (7.1, 7.2) attached is closed down, between each one longitudinal spar (15.1, 15.2) of the chassis frame and the transmission (16) through to a below the longitudinal beams (15.1, 15.2) of the chassis frame arranged two cylinder banks (2.1, 2.2) common pre-muffler (8) which internally has a hydrolysis catalytic converter (10) and at least one oxidation catalytic converter (9) and downstream of which there is a main silencer (13) with at least one integrated SCR catalytic converter (14).

Description

The invention relates to the exhaust system in a commercial vehicle with an internal combustion engine with V-shaped cylinder banks, wherein the exhaust ducts each lead to a cylinder bank in a common exhaust manifold and the internal combustion engine, together with a flanged to the engine transmission between two longitudinal members of a chassis frame of a commercial vehicle is arranged so that the exhaust manifolds extend above the longitudinal beams and wherein a lying below the longitudinal beams exhaust aftertreatment system is provided which comprises at least one hydrolysis and downstream of this one SCR catalyst.

In today's conventional diesel internal combustion engines for commercial vehicles, it is necessary for reasons of environmental compatibility to limit the proportions of nitrogen oxides to a minimum. For this purpose, exhaust gas aftertreatment systems are provided, which inject aqueous urea solution into the hot exhaust gas upstream of a hydrolysis catalytic converter arranged in the exhaust gas line, which is then converted into ammonia in the hydrolysis catalytic converter. Downstream of the hydrolysis catalyst, a so-called SCR catalyst is provided which, with the aid of the ammonia produced in the hydrolysis catalyst, causes the actual reduction of the nitrogen oxides (NO x). Such systems are for. B. from the DE 40 38 054 A1 known.

In replacement of the freezing at temperatures below -11.5 degrees Celsius and thus problematic in the use of aqueous urea solution, it is also known ammonia carrier in solid form z. B. solid urea, which is the upstream of a corresponding hydrolysis catalyst fed to the exhaust gas stream. Such a device is for example in the DE 102 52 734 A1 described.

From the DE 101 23 359 A1 Finally, it is known to arrange the hydrolysis catalytic converter in the front silencer and the SCR catalytic converter in the main silencer of an internal combustion engine.

For purifying exhaust gas of an internal combustion engine, which contains nitrogen oxides and soot particles, discloses DE 103 23 607 A1 a device with an oxidation catalyst, a particulate filter and an SCR catalyst. The SCR catalyst together with the particulate filter forms a unit which can be separated without destroying the catalyst and filter in the SCR catalyst and particulate filter.

From the EP 1 321 641 A1 For example, an exhaust emission purifying apparatus for a diesel engine is known which includes a first exhaust emission purifier disposed in an exhaust passage of an engine having a first regenerating type diesel particulate filter and a first SCR catalyst, a bypass exhaust passage adjacent to an exhaust passage on the upstream side a first exhaust emission purifier, a second exhaust emission purifier disposed in the bypass exhaust passage with a second regenerative type diesel particulate filter and a second SCR catalyst, and a NOx purifying reducing agent supply means disposed upstream of a branch portion of the bypass exhaust passage , Further, the exhaust emission purifying apparatus has exhaust gas temperature range detecting means for detecting an exhaust gas temperature range of an engine, exhaust gas temperature increasing means for increasing the exhaust gas temperature by means of a combination of an intake throttle valve and an exhaust gas introducing mechanism for opening an exhaust passage of a cylinder during an intake stroke, a passage switching means for controlling the flow of the exhaust gas the bypass exhaust passage and control means for controlling the exhaust temperature increasing means and the passage switching means in accordance with an exhaust gas temperature range detected by the exhaust gas temperature range detecting means. The control device is constructed such that, when the exhaust gas temperature range detecting means detects that the exhaust gas temperature is within a predetermined low temperature range, the exhaust temperature increasing means increases the exhaust gas temperature, and the channel switching means switches the channel in such a manner that the exhaust gas flows through the bypass exhaust gas passage and after has caused the exhaust gas to pass through the second exhaust emission purifier, causes the exhaust gas to pass through the first exhaust emission purifier.

Further, the EP 1 371 824 A1 a fossil fuel power plant having a smoke removal passage with a smoke cleaning arrangement. The arrangement includes a muffler followed by a nitrogen oxide selective reduction catalyst converter. The silencer in particular contains only solid components without loose insulation. The muffler also has a mixing area in which smoke is mixed with a reagent and it reduces noise emissions in the frequency range of 125-500 Hz. The muffler has a channel with a series of wall openings which are enclosed by a cavity wall. The cavity contains one or more perforated metal plates.

Further, the US 3 631 792 A an internal combustion engine exhaust afterburner using a valveless catalytic combustor in which acoustic resonance combustion is maintained by utilizing the exhaust effluent of the engine. The sonic wave activity helps to keep the catalyst surface clean by a cleaning process, with the catalyst assisting in maintaining resonant combustion.

For thermal reasons, the above-mentioned exhaust aftertreatment systems are to be arranged as close as possible to the exhaust manifold of the internal combustion engine.

In commercial vehicles, especially those with high performance, it is common to use internal combustion engines with V-shaped arranged cylinder banks. In these internal combustion engines, the exhaust manifolds usually extend at the top of the outsides parallel to the cylinder banks. There, however, is very limited in the installation of such an internal combustion engine in a commercial vehicle, especially a truck, the available space, especially when the internal combustion engine, as is common today, has turbocharger for charging. An accommodation of hydrolysis catalysts in this area is therefore extremely problematic, especially if they are integrated in an advantageous manner in pre-muffler. A thermally favorable housing of hydrolysis catalysts in commercial vehicles of the type described above is further contrary, that the internal combustion engine is usually arranged on a support frame, wherein the exhaust manifolds extend above the longitudinal beams of the support frame, the muffler, however, lie in a plane below the longitudinal beams. In previously conventional constructions without exhaust aftertreatment, the exhaust pipes have been led around the longitudinal bars outside around down, but this is for arrangements in which the hydrolysis in a plane below the longitudinal beams, z. B. is arranged in the front silencer, thermally very unfavorable and claimed in the area in which the exhaust pipes lead past the longitudinal beams, relatively much space.

Based on the above prior art, it is therefore an object of the invention to provide an exhaust system that allows a favorable thermal connection of the hydrolysis and minimizes the space required for the exhaust pipes.

The object is achieved by the characterizing features of claim 1, advantageous embodiments of the invention are characterized in the dependent claims.

The solution of the problem provides that the above lying above the chassis frame exhaust manifolds are each connected via a turbine of an exhaust gas turbocharger with exhaust pipes, each leading between the longitudinal beams and flanged to the engine gear down and open into a arranged below the longitudinal beams preshaped in which the hydrolysis catalytic converter and at least one oxidation catalytic converter are integrated and which is followed downstream by a main silencer with at least one integrated SCR catalytic converter. Through this exhaust system ensures that the distance between exhaust manifold and hydrolysis catalyst is bridged by the shortest route and with minimal space stress.

To improve the thermal connection of the hydrolysis catalyst, it may also be advantageous to insulate the exhaust pipes at least in the region between the longitudinal spar and the transmission, so that the insulation on the one hand minimizes the heat loss of the exhaust gas and on the other hand the function of a heat shield to the transmission or the respective longitudinal spar takes over.

Examples of the invention and advantageous embodiments are explained in more detail with reference to the drawings.

Show it:

1 an installed in a commercial vehicle engine with flanged gearbox and exhaust tract in plan view from above

2 the arrangement 1 in side view A common arrangement of engine and transmission in commercial vehicles is in 1 in supervision of the arrangement and in 2 shown in side view. Identical components are each provided with the same reference numerals.

The internal combustion engine shown 1 has two V-shaped arranged cylinder banks 2.1 . 2.2 on. The outlet channels (not shown) of the cylinder banks 2.1 . 2.2 are over exhaust manifold 3.1 . 3.2 with exhaust manifolds 4.1 . 4.2 connected. In internal combustion engines of this type are the exhaust manifold 3.1 . 3.2 and the exhaust manifolds 4.1 . 4.2 usually each right and left of the longitudinal axis of the internal combustion engine in its upper region. The exhaust manifolds 4.1 . 4.2 are with the inlets of turbines 5.1 . 5.2 of exhaust gas turbochargers 6.1 . 6.2 connected to the compressors of the turbocharger 6.1 . 6.2 Act. The outlets of the turbines 5.1 . 5.2 lead into exhaust pipes 7.1 . 7.2 , which in turn downstream in a pre-silencer 8th lead, in turn, downstream with a main silencer 13 connected is.

In the front silencer 8th are located next to a feeder 11 , by means of a metering device external to the pre-silencer 12 the reducing agent, for. As aqueous urea solution, supplies, a hydrolysis 10 and a z. B. consisting of two modules oxidation catalyst. Im the main muffler 13 is integrated in the example of five modules SCR catalyst.

To the internal combustion engine 1 is flanged in the 1 and 2 a gearbox 16 shown. The combination of internal combustion engine 1 and gear 16 is in a chassis frame of a commercial vehicle, for. B. a truck, from which the two longitudinal beams 15.1 . 15.2 in the 1 and 2 are shown.

In the common installation situation in trucks, the exhaust manifolds are located 4.1 . 4.2 and turbines 5.1 . 5.2 above the longitudinal bars 15.1 . 15.2 of the chassis frame, while the front silencer 8th and the main silencer 13 below the longitudinal bars 15.1 . 15.2 are arranged.

For connecting the outlets of the turbines located above the longitudinal struts 5.1 . 5.2 with the pre-silencer below 8th are the exhaust pipes 7.1 . 7.2 arranged so that they are from the turbines 5.1 . 5.2 each down, between the gearbox 16 and the respective adjacent longitudinal spar 15.1 . 15.2 through and then back to where they are in the front silencer 8th are merged.

To shield the transmission against inadmissible heat radiation, and to shield the exhaust against heat loss, the exhaust pipes 7.1 . 7.2 with insulation 20.1 . 20.2 be provided. The insulation of the exhaust pipes 7.1 . 7.2 against heat loss may therefore be necessary, because the exhaust gas on the distance between the turbines 5.1 . 5.2 and the hydrolysis catalyst 10 would cool too much and so the implementation of z. As aqueous urea solution in ammonia, for which high exhaust gas temperatures are required, could not be done in the necessary manner.

Due to the chosen construction, on the one hand, the shielding of heat-sensitive areas of the vehicle and, on the other hand, the protection of the exhaust gas from excessive heat loss on the way to the hydrolysis catalytic converter can be ideally combined.

Reference is made to the publications mentioned in the introduction to the chemical processes occurring in the exhaust aftertreatment.

Claims (2)

Exhaust duct in a commercial vehicle with an internal combustion engine with cylinder banks arranged in a V-shape, the exhaust ducts in each case being a cylinder bank ( 2.1 . 2.2 ) in a common exhaust manifold ( 4.1 . 4.2 ) and the internal combustion engine ( 1 ), together with a to the internal combustion engine ( 1 ) flanged gear ( 16 ), between two longitudinal spars ( 15.1 . 15.2 ) of a chassis frame of a commercial vehicle are arranged so that the exhaust manifolds ( 4.1 . 4.2 ) above the longitudinal spars ( 15.1 . 15.2 ) and wherein one below the longitudinal beams ( 15.1 . 15.2 ) is provided, which comprises at least one hydrolysis catalytic converter ( 10 ) and downstream of this one SCR catalyst ( 14 ), Characterized in that each exhaust manifold ( 4.1 . 4.2 ) at its end with the inlet of at least one turbine ( 5.1 . 5.2 ) at least one exhaust gas turbocharger ( 6.1 . 6.2 ), the turbine ( 5.1 . 5.2 ) downstream of a respective exhaust pipe ( 7.1 . 7.2 ) which is connected to the bottom, between each longitudinal beam ( 15.1 . 15.2 ) of the chassis frame and the transmission ( 16 ) through to one below the longitudinal spars ( 15.1 . 15.2 ) of the chassis frame arranged two cylinder banks ( 2.1 . 2.2 ) common pre-silencer ( 8th ), which internally contains a hydrolysis catalyst ( 10 ) and at least one oxidation catalyst ( 9 ) and the downstream of a main muffler ( 13 ) with at least one integrated SCR catalyst ( 14 ) follows. Exhaust duct according to claim 1, characterized in that the exhaust pipes ( 7.1 . 7.2 ), at least in the area in which they are between the transmission ( 16 ) and the longitudinal beams ( 15.1 . 15.2 ) of the chassis frame, are thermally insulated.

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