DE102011078181A1 - Apparatus and method for introducing a reducing agent in an exhaust line - Google Patents

Abstract

The invention relates to a device for introducing a reducing agent into an exhaust gas line of an internal combustion engine having at least one hollow element (4, 6, 18) arranged in the exhaust gas line and at least one feed line which is designed to supply reducing agent to the hollow element (4, 6; , The at least one hollow element (4, 6, 18) extends in a plane which is aligned transversely to the flow direction of the exhaust gases in the exhaust gas line. At least one opening (12) is formed in the hollow element (4, 6, 18), which makes it possible to introduce the reducing agent from the hollow element (4, 6, 18) into the exhaust gas line.

Description

The invention relates to a device and a method for introducing a reducing agent into an exhaust line of an internal combustion engine in order to achieve the most uniform possible distribution of the reducing agent in the exhaust system.

State of the art:

In the development of internal combustion engines, the adherence to limit values for the pollutant emissions is the highest goal. In the case of diesel engines in particular, NOx reduction is absolutely necessary in order to comply with the prescribed limits.

One way of reducing NOx is Selective Catalytic Reduction (SCR). In this system, a urea water solution is sprayed into the exhaust tract. In the hot exhaust gases, ammonia gas develops, with which the nitrogen oxides can be selectively reduced.

The urea water solution can be added to the exhaust in various ways. Alternatively, the exhaust gases instead of a urea water solution and ammonia can be supplied in gaseous form.

DE 197 38 859 A1 shows a mixture delivery device for an exhaust system in which an annular spray body having a circumferential distribution channel and a plurality of spray channels is introduced into the exhaust line. A mixture of compressed gas and urea-water solution is fed via a mixture supply line and introduced into the exhaust gas flow upstream of the catalyst.

Disclosure of the invention:

An object of the invention is to provide a device for injecting a reducing agent, in particular a gaseous reducing agent such as ammonia, into the exhaust gas line of an internal combustion engine with which the most uniform possible distribution of the reducing agent in the exhaust gas system is achieved.

The object is achieved by a device according to the invention according to independent claim 1 and a method according to claim 10. The dependent claims 2 to 9 describe advantageous embodiments of a device according to the invention.

An apparatus according to the invention for introducing a reducing agent into an exhaust gas line of an internal combustion engine has at least one hollow element arranged in the exhaust gas line and at least one feed line, which is designed to supply reducing agent to the hollow element. The at least one hollow element extends in a plane which is aligned transversely to the flow direction of the exhaust gases in the exhaust system. In the hollow element, at least one opening is formed which allows reducing agent to flow from the hollow element into the exhaust gas line.

The inventive arrangement of the hollow elements and openings of a device according to the invention, a uniform distribution of the concentration of the reducing agent in the exhaust line is achieved when introducing the gaseous reducing agent in the exhaust system. This results in an increase in efficiency, especially in the case of short mixing sections. In the case of direct metering of ammonia, a catalyst arranged in the exhaust gas line does not have to be thermo-thermally insulated. Hydrolysis perform, which is particularly advantageous at low temperatures.

The invention also encompasses a method of introducing a particular gaseous reducing agent into an exhaust gas line of an internal combustion engine, wherein the method includes, in particular, introducing the particular gaseous reducing agent into the exhaust gas line by means of a device according to the invention. The inventive introduction of a particular gaseous reducing agent is a particularly homogeneous mixing of the introduced reducing agent with the exhaust gases, which flow through the exhaust line achieved. This allows a particularly effective reduction of the nitrogen oxides contained in the exhaust gases over the entire cross section of the exhaust system.

In one embodiment, the device according to the invention has at least one opening, which is aligned so that the reducing agent can flow parallel to the flow direction of the exhaust gases in the exhaust line from the hollow element in the exhaust line. Alternatively or additionally, at least one of the openings may be aligned such that the reducing agent flows with a transverse component, in particular at a right angle, to the flow direction of the exhaust gases in the exhaust gas line into the exhaust gas line. As a result of the orientation of the openings through which the reducing agent exits the hollow element and flows into the exhaust line, the inflow angle in which the reducing agent flows from the hollow element into the exhaust line can be suitably adjusted in order to ensure optimum and in particular particularly uniform distribution of the reducing agent to reach in the exhaust gases in the exhaust system.

In one embodiment, the at least one hollow element is helical, so that it extends spirally from the center of the exhaust line in its edge region. In this case, the hollow element is preferably arranged in a plane which is aligned transversely, in particular perpendicularly, to the flow direction of the exhaust gases in the exhaust gas line. By a helical or spiral-shaped hollow element, the entire cross section of the exhaust gas line can be covered by a single hollow element. With a single hollow element, a uniform distribution of the reducing agent in the exhaust system can be achieved. The cost of additional hollow elements and their assembly can be saved.

The reducing agent can be supplied to the hollow element in the center of the exhaust gas line, so that it flows through the helical or spiral-shaped hollow element into the outer regions of the exhaust gas line. Alternatively, the reducing agent may be supplied to the screw-shaped or spiral-shaped hollow element at its outer end, so that it flows through the hollow element in the direction of the center of the exhaust gas line. Along the course of the hollow element, openings are formed through which, during operation, a part of the reducing agent flows out of the hollow element into the exhaust gas line and the reducing agent is distributed uniformly over the entire cross section of the exhaust gas line.

In one exemplary embodiment, the at least one hollow element extends in the radial direction through the cross section of the exhaust gas line. Along the course of the hollow element, openings are formed through which a part of the reducing agent in each case flows out of the hollow element into the exhaust gas line during operation. By means of a hollow element extending in the radial direction through a cross section of the exhaust gas line, different regions at different radial distances from the center or the periphery of the exhaust gas line can be uniformly supplied with reducing agent.

In one embodiment, a plurality of hollow elements are provided, and the hollow elements are preferably arranged in the form of a grid, which is aligned transversely, in particular at a right angle to the flow direction of the exhaust gases in the exhaust system. In each of the hollow elements, a number of openings is provided, which allow an exit of reducing agent in the exhaust system.

By lattice-shaped arranged hollow elements, in each of which a plurality of openings are formed, the cross section of the exhaust line can be particularly uniformly supplied with reducing agent, so that a particularly homogeneous mixing of the exhaust gases in the exhaust line can be achieved with the supplied reducing agent.

In one embodiment, mixer flaps are arranged on and / or between the hollow elements, which flaps are designed to deflect or deflect the exhaust gas flow in the exhaust gas line. By such mixer flaps, which deflect the exhaust gas flow in the exhaust line or divert the mixing of the exhaust gases can be improved with the reducing agent in order to achieve the most homogeneous distribution of the reducing agent in the exhaust gases.

In one embodiment, an annular feed line is provided, which is designed to supply the hollow element or the hollow elements to be introduced into the exhaust line reducing agent. An annular feed line may be formed inside or outside the exhaust line. By an annular feed line, the reducing agent is particularly evenly supplied to the hollow elements arranged in the exhaust line, whereby a particularly homogeneous distribution of the reducing agent is achieved in the exhaust system.

In one embodiment, the device according to the invention for introducing the reducing agent is attached to a sealing ring or flange, which is arranged in the exhaust pipe. At a arranged in the exhaust gas ring and / or flange, a device according to the invention can be mounted particularly simple and inexpensive. In particular, additional interruptions (cuts) in the exhaust pipe, which can lead to leakage, can be avoided.

The invention will be explained in more detail below with reference to the attached figures. Showing:

1 a first embodiment of a device according to the invention.

2 A second embodiment of a device according to the invention.

3 A third embodiment of a device according to the invention.

4 A fourth embodiment of a device according to the invention.

5 A fifth embodiment of a device according to the invention.

6 A sixth embodiment of a device according to the invention.

In the 1 to 6 extends the exhaust line each perpendicular to the plane, so that the figures show a cross section through the exhaust system.

In all figures, like reference numerals designate the same or similar components. A description of the components is provided only for the first embodiment, it being understood that the same description applies to the following embodiments, unless expressly stated otherwise.

A device according to the invention according to a first embodiment, as shown in the 1 is shown, is disposed at a position of the exhaust line, at the two pipes of the exhaust line abut each other and the transition through a sealing ring 2 is sealed.

The inventive device of the first embodiment has a loop 8th on, which is at the height of the sealing ring 2 extends around the circumference of the exhaust line and at least one point with a supply line 10 connected is. The supply line 10 is trained to the ring line 8th the reducing agent to be injected. in this case a gaseous reducing agent, from an external, in the 1 supply source not shown.

Mutually opposite points of the loop 8th are by hollow trained webs 4 . 6 that through in the seal 2 formed penetrate breakthroughs in the exhaust system and extend through this, connected to each other. That in the 1 embodiment shown has vertically extending webs 4 and horizontal walkways 6 on, which form a rectangular grid inside the exhaust line. The right-angled arrangement of the bars 4 . 6 However, is only exemplary and there are arrangements are conceivable in which the webs 4 . 6 are arranged at a different angle to each other and so form a pointed or obtuse-angled grid.

At the jetties 4 . 6 are mixer flaps 14 attached, which are adapted to deflect the perpendicular to the plane through the exhaust gas flowing exhaust gases and in particular to swirl, so as to bring about a homogeneous mixing of the exhaust gases in the exhaust line with the injected reducing agent.

In the in the 1 embodiment shown are the mixer flaps 14 designed such that they divert the exhaust gases flowing through the exhaust line alternately up and down; This achieves a particularly effective mixing of the exhaust gases with the injected reducing agent.

The hollow trained webs 4 . 6 stand in connection with the ring line 8th and have openings inside the exhaust line 12 on. Through the supply line 10 the ring line 8th supplied reducing agent flows from the loop 8th in the jetties 4 . 6 trained cavities and from there through the openings 12 into the exhaust system, where it goes with the through the mixer flaps 14 entangled exhaust gases mixed to be arranged by means of a downstream of the device, in the 1 Not shown catalyst to reduce the nitrogen oxides contained in the exhaust gases.

2 shows an alternative embodiment of a device according to the invention. Instead of webs 4 . 6 , which are arranged in the form of a rectangular grid, are the hollow elements 18 formed as three concentrically arranged around the center of the exhaust gas line rings, passing through a radially extending from the outer periphery to the center of the exhaust line feed line 10 connected to each other. The supply line 10 The reducing agent from an external source, not shown, the ring-shaped hollow elements 18 to. The annular hollow elements each have a number of openings 12 on, through which the reducing agent from the annular hollow elements 18 flows into the exhaust system. Between the annular hollow elements 18 are mixer flaps 14 arranged to divert the exhaust gases flowing through the exhaust line, and in particular to swirl, to effect a uniform distribution of the supplied reducing agent with the exhaust gases.

In the radial direction extending webs 20 , which the annular hollow elements 18 connect together, increase the strength and in particular the rigidity of a device according to the invention according to the second embodiment.

3 shows a third embodiment of a device according to the invention, at the height of a flange 3 , which is formed on an exhaust line, is arranged. The flange 3 has a number of holes in its outer area 5 on, through which the flange 3 can be screwed with a second flange.

On the radially inner side of the flange 3 is a loop around the exhaust system 8th formed, which has a radial inlet 10 can be supplied with the reducing agent to be injected.

From the ring line 8th branches several radial hollow elements 18 which extend from the periphery towards the center of the exhaust line. The hollow elements 18 can all be the same length or as in the 3 shown to have different lengths and are each with multiple openings 12 formed, through which the reducing agent to be injected, the radial hollow elements 18 through the inlet 10 and the ring line 8th has been supplied from the hollow elements 18 can flow into the exhaust system.

4 shows a further embodiment of a device according to the invention, in which the hollow elements 18 are arranged comb-like. In the in 4 As shown, the hollow elements extend 18 starting from the supply line 10 essentially parallel to one another through the exhaust gas line. It is understood that the hollow elements 18 can also be at a certain angle to each other.

The from the supply line 10 outgoing, comb-like arranged hollow elements 18 can go through in the 4 not shown webs may be fixed to the periphery of the exhaust line to increase the mechanical stability of the device.

Also in this embodiment, the hollow elements 18 each several openings 12 on, by which the reducing agent to be injected from the hollow elements during operation 18 into the exhaust system. Also these openings 12 can be aligned parallel, obliquely and / or at a right angle to the flow direction of the exhaust gases in the exhaust system.

5 shows a fifth embodiment of a device according to the invention. The device according to the fifth embodiment has a single hollow element 18 which spirally extends from an outer portion of the exhaust line to its center. About one at an outer end of the hollow element 18 trained supply line 10 becomes the hollow element 18 supplied to the injected reducing agent. The reducing agent flows through the helical element 18 from an outer peripheral portion of the exhaust line toward the center thereof. Through along the hollow element 18 trained openings 12 In each case, a portion of the supplied reducing agent enters the exhaust line, so that the reducing agent is introduced uniformly over the entire cross section in the exhaust line in order to achieve the most homogeneous possible mixing of the reducing agent with the exhaust gases in the exhaust system.

In the radial direction adjacent areas of the screw-shaped hollow element 18 are by substantially radially extending webs 20 interconnected to the mechanical stability of the helical screw or spiral element 18 to increase. In particular, such a hollow element 18 that passes through webs extending in the radial direction 20 is reinforced, resistant to forces caused by the exhaust gas flow in the exhaust line to the hollow element 18 be exercised.

That in the 5 shown snail or spiral hollow element 18 has about three turns. However, this is only an example and the number of turns may depend on the diameter of the exhaust line and the diameter of the hollow element 18 be selected suitable.

6 shows a further embodiment of a device according to the invention, which also has a helical or spiral-shaped hollow element 18 extending in a plane of the exhaust line, which is aligned at a right angle to the flow direction of the exhaust gases in the exhaust line.

In contrast to that in the 5 the embodiment shown, the supply line runs 10 through which the hollow element 18 the reducing agent to be introduced is supplied radially from the outer region of the exhaust gas line to its center and there goes into the hollow element 18 over, so that the reducing agent to be injected the hollow element 18 through the supply line 10 in the center of the exhaust line, and through the hollow element 18 spirally flows outwards. In each case, a part of the reducing agent passes through in the hollow element 18 trained openings 12 in the exhaust system.

Also in this embodiment are areas of the hollow member 18 , which are adjacent to each other in the radial direction, by radially extending webs 20 interconnected to the mechanical stability of the device and in particular of the hollow element 18 to increase.

At the jetties 20 can additionally in the 5 and 6 Not shown mixer flaps are arranged as shown in the 1 and 2 are shown to influence the exhaust gas flow in the exhaust line and to achieve a better mixing of the exhaust gases with the injected reducing agent.

In all embodiments shown, the openings 12 be arranged parallel to the flow direction of the exhaust gases in the exhaust system and at any, in particular right angle to the flow direction of the exhaust gases to achieve optimal, in particular homogeneous mixing of the injected reducing agent with the exhaust gases flowing through the exhaust line.

The openings 12 preferably have a diameter which is in each case smaller than one tenth of the diameter of the respective hollow element 4 . 6 . 18 is the pressure drop in the hollow element 4 . 6 . 18 To keep as low as possible over its course and thus to ensure a uniform introduction of the reducing agent in the exhaust system.

A device according to the invention, as exemplified in the 1 to 6 is shown, makes it possible to effectively introduce a gaseous reducing agent in the exhaust line of an internal combustion engine and thereby achieve a very uniform distribution of the reducing agent in the exhaust system. The invention is not limited to the embodiments shown in the figures, but includes all embodiments that fall within the scope of the following claims.

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

• DE 19738859 A1 [0005]

Claims (10)

Device for introducing a reducing agent into an exhaust gas line of an internal combustion engine, with at least one hollow element arranged in the exhaust gas line (US Pat. 4 . 6 ; 18 ), wherein in the hollow element ( 4 . 6 ; 18 ) at least one opening ( 12 ) is formed, which makes it possible, the reducing agent from the hollow element ( 4 . 6 ; 18 ) to introduce into the exhaust line, and at least one supply line, which is adapted to the hollow element ( 4 . 6 ; 18 ) supply the reducing agent, characterized in that the at least one hollow element ( 4 . 6 ; 18 ) extends in a plane which is aligned transversely to the flow direction of the exhaust gases in the exhaust line. Device according to claim 1, wherein the at least one opening ( 12 ) is aligned so that the reducing agent parallel to the flow direction of the exhaust gases from the cavity ( 4 . 6 ; 18 ) flows into the exhaust system. Device according to claim 1, wherein at least one opening ( 12 ) is aligned so that the reducing agent with a transverse component to the flow direction of the exhaust gases in the exhaust line, in particular at right angles, from the cavity ( 4 . 6 ; 18 ) flows into the exhaust system. Device according to one of the preceding claims, characterized in that the at least one hollow element ( 18 ) is formed snail-shaped. Device according to one of the preceding claims, characterized in that the at least one hollow element ( 18 ) extends in the radial direction through the exhaust line. Device according to one of the preceding claims, characterized in that a plurality of hollow elements ( 4 . 6 ) are provided and the hollow elements ( 4 . 6 ) are arranged in the form of a grid transverse to the flow direction of the exhaust gases in the exhaust line. Device according to one of the preceding claims with an annular feed line ( 8th ), which is arranged along the circumference of the exhaust line and is formed to the at least one hollow element ( 4 . 6 ; 18 ) to supply the reducing agent. Device according to one of the preceding claims, wherein the device blends ( 14 ), which are designed to influence the exhaust gas flow in the exhaust line and in particular to deflect. Device according to one of the preceding claims, wherein the device is attached to a flange ( 3 ) or a sealing ring ( 2 ) of the exhaust line is arranged. A method of introducing a reducing agent, in particular a gaseous reducing agent, into an exhaust gas line of an internal combustion engine, the method including introducing the gaseous reducing agent into the exhaust gas line by a device according to one of claims 1 to 9.

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