DE102008051872A1 - two-fluid nozzle - Google Patents

Abstract

Two-fluid nozzle, in particular for atomizing a liquid by means of compressed air, in particular for injecting a urea solution in an exhaust system of an internal combustion engine for selective catalytic reduction, wherein the nozzle has at least a first nozzle opening (11) and a second nozzle opening (21), wherein the second opening (21 ) is formed by an annular gap, which is arranged concentrically to the first opening (11).

Description

The The invention relates to a two-fluid nozzle, in particular for Atomization of a liquid by means of compressed air, in particular for the injection of a urea solution in an exhaust system of an internal combustion engine, wherein the nozzle at least a first nozzle opening and a second Has nozzle opening.

such Two-fluid nozzles for atomizing liquids are known. In particular, such two-fluid nozzles come for the atomization of paints used. To the injection of urea into the exhaust stream of an internal combustion engine One-hole or multi-hole nozzles used. Here is the Aerosol already generated in an upstream mixing chamber.

In Exhaust systems in which the urea solution by means of compressed air injected into the exhaust stream, are currently 1-hole nozzles or multi-hole nozzles used in which the aerosol formation takes place in an upstream module. This means that through the nozzles used the aerosol is only distributed. Next is the geometry of the nozzle opening used only a small variability of the exit angle possible. The multi-hole nozzle has the further disadvantage that it the Aerosol radially distributed and thus contact the aerosol with the pipe wall favors.

The known compressed air-free urea injection systems work in usually with active nozzles (valves). This means, that on the hot exhaust pipe electrically active components must be mounted. These must be accordingly the temperature specifications of the manufacturer to be cooled. This is usually done by the cooling water. This increases the complexity of the nozzle system considerably. Next is a much larger space for the installation and the hoses needed.

adversely in the known two-fluid nozzles for atomization a Flüssigkleit means of compressed air, it is thus that this claim a relatively large installation space, since they must comprise an upstream mixing chamber. Farther A disadvantage of the known two-fluid nozzles is that This is a relatively high number of components and a very complex design exhibit.

The The object of the invention is to provide a generic Two-fluid nozzle in such a way that the required Space can be reduced and the nozzle a total of has less complex structure with a reduced number of parts. Next is the cost-effective production of a nozzle be allowed, in which the aerosol formation preferably only in the exhaust gas flow.

These The object is achieved by a two-fluid nozzle solved according to claim 1. Further advantageous Further developments of the invention are in the subclaims specified.

Especially advantageous in the two-fluid nozzle, in particular for atomization a liquid by means of compressed air, in particular for injection a urea solution in an exhaust system of an internal combustion engine, wherein the nozzle at least a first nozzle opening and having a second nozzle opening, it is that the second opening formed by an annular gap which is arranged concentrically to the first opening.

Consequently is it possible through the first nozzle opening to conduct the liquid to be atomized and through the concentric surrounding this first nozzle opening Annular gap to direct the compressed air, so when ejecting the fluid through the compressed air the liquid atomized and thus formed the required aerosol becomes. For this purpose, the two substances (urea solution and compressed air) are supplied to the nozzle in separate ways become.

Accordingly, such a two-substance nozzle is particularly advantageously used in the injection of a urea solution into the exhaust gas stream of an internal combustion engine for the reduction of nitrogen oxides, ie for the injection of urea solution, in particular AdBlue DIN 70070 , for selective catalytic reduction.

Preferably is the first opening with a first chamber and / or Supply line connected, with the first opening of this Chamber and / or supply line with the liquid to be atomized is fed.

Prefers is the second opening with a second chamber and / or Connected supply line and is fed by this with compressed air.

The The basic principle of the nozzle is thus a mixture of the components and the associated aerosol formation outside the Component. In this case, the liquid to be atomized is through the first chamber directed. The atomizing medium compressed air is over supplied to the second chamber. The atomization medium is directed around the first chamber. At the nozzle tip an annular gap is formed, which is the first nozzle opening from which the liquid to be atomized emerges, concentrically surrounds. Through the annular gap becomes the sputtering medium passed in the form of compressed air. The aerosol formation thus takes place outside the nozzle, reducing component complexity can be reduced in an advantageous manner.

The second concentric nozzle opening In particular, it can also be formed by a plurality of smaller gaps, gap sections or openings, which are arranged concentrically to the first nozzle opening, ie lying on a circle or circular sections around the first nozzle opening, and form an annular gap or an annular gap-like opening. All that is important here is that the second nozzle opening is concentric with the first nozzle opening in order to atomize the liquid emerging from the first nozzle opening by means of compressed air from the second concentric nozzle opening.

The Nozzle can be made in one piece. The nozzle can be produced by the metal powder injection molding process be, d. H. by metal powder injection molding (MIM, metal injection molding). Here, the cavity during injection of the component by a Plastic body formed. This plastic body is evaporated during subsequent debindering. In particular, this is the binder matched to the material of the plastic body.

In a preferred embodiment is the nozzle executed in several parts, in particular two parts, in particular such that a first component is the first nozzle opening and a second component, the first component at least partially surrounds, leaving the second nozzle opening between the first and the second component is formed.

By this embodiment, in which the second component, the first component at least partially surrounds or embraces, can simultaneously between the two components of the second opening forming annular gap be formed, the first nozzle opening concentrically encompassing, d. H. one to the first circular Nozzle opening forms a concentric ring.

Prefers Both nozzle openings are each with a chamber and / or supply line, wherein the chambers and / or supply lines Connection areas for hoses, pipes, flanges or have the like, in particular connecting piece. Especially the connecting pieces can be designed in such a way that hoses or the like slipped over the neck can be, with the connecting pieces designed in such a way they may be barb-like heels so that hoses can not slide down, but form a tight fit, especially through training a form and / or adhesion.

In a preferred embodiment are on the outside of the component Cooling ribs arranged. For cooling the component surface and the component, d. H. for cooling the two-fluid nozzle and for heat dissipation cooling fins are arranged.

Preferably the nozzle has a thermal insulation layer on the outside in particular, the nozzle may be a ceramic coating exhibit. By the arrangement of a thermal insulation layer, especially a ceramic coating, the nozzle can Effectively against heat as in the exhaust system of an internal combustion engine occurs, be protected.

Preferably is the nozzle by means of a metal powder injection molding process manufactured, d. H. by metal powder injection molding (MIM, Metal Injection Molding).

hereby It is possible, even for larger quantities and / or complex technical parts an effective Apply manufacturing processes with excellent tolerances.

The nozzle is preferably made of a high-temperature-resistant and temperature-resistant material, since the ambient temperature of the nozzle can reach up to 600 ° C, when these nozzles for injection of urea solution, such as AdBlue, in particular according to DIN 70070 for selective catalytic reduction (SCR) are used in internal combustion engines in the exhaust system. As a rule, these materials belong to the group of difficult-to-machine metals and can therefore only be processed at great expense. This disadvantage is overcome by the production method of metal powder injection molding (MIM, Metal Injection Molding).

Preferably be the components and / or the fully assembled Nozzle, the multi-part, in particular two parts executed may be debinded and / or sintered and / or ceramic coated.

Preferably be the components and / or the fully assembled Nozzle of several parts in another thermal Process condensed. This achieves the material end properties. at This process is called sintering or burning. Subsequently a ceramic coating can be applied.

Preferably the nozzle is made in several parts, the Components in particular can be glued together.

In The figures are several embodiments of the invention Two-fluid nozzles shown in sectional views and are explained below. Show it:

1 A first embodiment of a two-fluid nozzle according to the invention in section;

2 A second embodiment of a two-fluid nozzle according to the invention in section;

3 A third embodiment of a two-fluid nozzle according to the invention in section;

4 A fourth embodiment of a two-fluid nozzle according to the invention in section;

5 An enlarged section of a fifth embodiment of a two-fluid nozzle according to the invention in section;

6 A sixth embodiment of a two-fluid nozzle according to the invention in section.

identical Reference numerals in the figures designate the same components of the various Embodiments of two-substance nozzles.

The nozzle according to 1 is formed by two components 10 . 20 , The first component 10 has a first nozzle opening 11 on, by a first chamber 12 with the liquid to be atomized, ie in the case of application as a nozzle in an exhaust aftertreatment system with urea solution, is fed.

The second component 20 overlaps the first component 10 in the way that between the two components 10 . 20 a second nozzle opening 21 forming annular gap, which from one to the second component 20 integrated chamber 22 with compressed air for atomization of the first nozzle opening 11 exiting liquid is applied. The annular gap 21 is concentric with the first nozzle opening 11 ,

The basic principle of the nozzle is a mixture of the components outside the component. This is done by the first chamber 12 passed the liquid to be atomized. The atomizing medium is compressed air via the second chamber 22 fed. The atomizing medium is around the first chamber 12 bypassed. At the nozzle tip is an annular gap 21 formed, through which the sputtering medium is passed. The arrangement of the mounting holes 31 . 32 for mounting the two components 10 . 20 respectively the entire arrangement can be varied according to the installation spaces. Drawn here is the elongated arrangement of the mounting holes 31 . 32 , The connection of the nozzle to the connecting lines for supplying compressed air and urea solution can be carried out by various methods. 1 shows the recording for glands. In 2 the receptacles for the hoses are already integrated in the upper part. The attachment of the nozzle can be done either by means of screws, rivets and the like.

In the chambers 12 . 22 are internal threads introduced, which serve as connection areas for the connecting leads for liquid and compressed air.

In the second embodiment according to 2 are connecting pieces 13 . 23 for attaching hoses for supplying liquid to the first nozzle opening 11 and for supplying compressed air to the second nozzle opening 21 intended. The pillars 13 . 23 have annular undercuts to ensure a tight fit of a deferred tube on the respective nozzle. The same connection piece has the embodiment according to 4 on.

For cooling the component surface and the component 10 can at the top 10 one or more ribs 14 . 15 be attached, as in 3 is shown. The number and size of cooling fins 14 . 15 as well as their location, the installation space and the necessary cooling capacity, ie the required heat transfer to the environment can be adjusted.

To reduce the heat input via the contact surface to the exhaust pipe of the exhaust aftertreatment system of an internal combustion engine, the nozzle at the bottom of the lower part 20 with a ceramic coating 30 be provided, as in the embodiment according to 4 the case is. The thermal insulation layer, ie the ceramic 30 , serves as a thermal insulator against excessive heat input into the components 10 . 20 the nozzle when used as a nozzle for injection of urea solution for selective catalytic reduction (SCR) in exhaust aftertreatment devices in internal combustion engines, since high temperatures occur here.

In 5 an enlarged section of a further embodiment is shown. To empty the nozzle and to prevent blockages by urea crystals can enter the chamber or supply line 12 through which the first nozzle opening 11 is fed, ribs 17 be introduced. After stopping the engine no cooling takes place through the urea solution more. The registered heat is now over the ribs 17 in the middle of the urea channel 12 directed. As a result, the urea is heated beyond the evaporation limit at the rib position. The resulting steam drives the urea column in front of it out of the nozzle 11 out.

The nozzles described here are made of only two parts 10 . 20 manufactured. These are the shell 10 with the chamber or the channel 12 and the chamber or channel 22 , as well as the lower part 20 , For the production of the individual parts 10 . 20 come here MIM (Metal Injection Molding) process, ie metal powder injection molding, is used.

The two items 10 . 20 are aligned after spraying each other and glued together. Subsequently, the component is debinded and sintered. This gives the component its final strength. After sintering, the ready-to-install component is obtained. Advantage of the method lies in the free contour design and in the achievable tolerance classes. The ceramic insulation layer 30 is sprayed on the component in a further operation and then fired.

The nozzle according to 6 is formed by a single component 6 comprising the first nozzle opening 11 coming from a first chamber 12 with the liquid to be atomized, ie in the case of application as a nozzle in an exhaust aftertreatment system with urea solution, is fed. Next, the component 6 the second nozzle opening 21 in the form of an annular gap, that of an integrated chamber 22 with compressed air for atomization of the first nozzle opening 11 exiting liquid is applied. The annular gap 21 is concentric with the first nozzle opening 11 ,

The nozzle openings 11 . 21 , the chambers 12 . 22 for feeding the nozzle openings 11 . 21 as well as the channels between the chambers 12 . 22 and nozzle openings 11 . 21 are in the one-piece nozzle body 6 integrated.

The nozzle according to 6 is manufactured as a one-piece component by means of the metal powder injection molding process, ie by metal powder injection molding (MIM, Metal Injection Molding). Here, the complex cavity ur training in the component 6 integrated chambers 12 . 22 and connecting channels to the nozzle openings 11 . 21 during spraying of the component 6 formed by a plastic body. This plastic body is evaporated during subsequent debindering. For this, the binder matched to the material of the plastic body.

In the chambers 12 . 22 are internal threads introduced, which serve as connection areas for the connecting leads for liquid and compressed air. The through holes 31 . 32 serve for mounting the nozzle body 6 ,

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited non-patent literature

• - DIN 70070 [0010]
• - DIN 70070 [0023]

Claims (10)

Two-fluid nozzle, in particular for atomizing a fluid by means of compressed air, in particular for injecting a urea solution in an exhaust system of an internal combustion engine for selective catalytic reduction, wherein the nozzle has at least one first nozzle opening ( 11 ) and a second nozzle opening ( 21 ), characterized in that the second opening ( 21 ) is formed by an annular gap leading to the first opening ( 11 ) is arranged concentrically. Nozzle according to claim 1, characterized in that the first opening ( 11 ) with a first chamber ( 12 ) and / or supply line is connected and fed by this with the liquid to be atomized. Nozzle according to claim 1 or 2, characterized in that the second opening ( 21 ) with a second chamber ( 22 ) and / or supply line is connected and is supplied by this with compressed air. Nozzle according to one of the preceding claims, characterized in that the nozzle is designed in several parts, in particular in two parts, in particular in such a way that a first component ( 10 ) the first nozzle opening ( 11 ), and a second component ( 20 ) the first component ( 10 ) at least partially surrounds, so that the second nozzle opening ( 21 ) between the first ( 10 ) and the second component ( 20 ) is formed. Nozzle according to one of the preceding claims, characterized in that both nozzle openings ( 11 . 21 ) each with a chamber and / or a supply line ( 12 . 22 ), the chambers and / or supply lines ( 12 . 22 ) Have connection areas for hoses, lines, flanges or the like, in particular connecting pieces ( 13 . 23 ). Nozzle according to one of the preceding claims, characterized in that on the outside cooling fins ( 14 . 15 ) are arranged. Nozzle according to one of the preceding claims, characterized in that on the outside a thermal insulation layer ( 30 ), in particular that the nozzle has a ceramic coating. Nozzle according to one of the preceding claims, characterized in that the components ( 10 . 20 ) of the nozzle are made by metal powder injection molding. Nozzle according to one of the preceding claims, characterized in that the nozzle is designed in several parts, wherein the components ( 10 . 20 ) are glued together. Nozzle according to one of the preceding claims, characterized in that the nozzle is debinded and / or sintered and / or ceramic coated.