DE102013102918B4 - ultrasonic evaporator - Google Patents

Abstract

System (1) comprising a nebulization device (2) and at least one exhaust gas-carrying exhaust element (3) as part of an exhaust system of an internal combustion engine, characterized in that the nebulization device (2) has a sonotrode (5), wherein the sonotrode (5) is formed from an ultrasound generator (5.1) and a mass coupled thereto (5.2) and a lance (2.2) with a channel (2.4) in which a medium to be atomized can be transported, wherein the atomiser (2) at least with a part of the lance (2.2 ) is arranged in the exhaust gas element (3) and the medium to be atomized in the exhaust gas element (3) is introduced nebulizable.

Description

The invention relates to a system consisting of a nebulizing or atomizing device and at least one exhaust-carrying exhaust element or exhaust pipe as part of an exhaust system of an internal combustion engine.

Nebulization or atomization is spoken of when a droplet size smaller than 100 μm is achieved. This includes smallest droplet sizes including evaporation due to cavitation effects.

From the US 5,326,254 A is known as an ultrasonic nebulizer nebulizer for use in an exhaust gas recirculation system of an internal combustion engine. For this purpose, it is provided that the nebulizer is connected to an air or vapor pressure source, since the atomization of a supplied for the exhaust gas cooling water flow is carried out using this pressure medium. The nozzle and the resonator plate are arranged within the gas stream. An ultrasonic generator on an electrical basis or a sonotrode is not described.

From the EP 1 633 493 B1 is an ultrasonic sputtering arrangement is known, which has an ultrasonic sonotrode, is sprayed by means of the liquid paint. Opposite to the front end of the sonotrode a reflector is provided. Between the sonotrode and the reflector several paint outlet nozzles are arranged. In operation, a standing ultrasonic wave is formed between the sonotrode and the reflector, since a multiple of half the wavelength is selected for the distance between the two. Due to the ultrasonic wave emerging from the paint outlet nozzles paint is atomized. The atomization power is highest where the standing ultrasonic wave has a maximum. The ultrasonic atomization arrangement is hereby arranged completely in the paint stream to be atomized.

Sonotrodes are tools that are put into resonance vibrations by the introduction of high-frequency mechanical vibrations such as ultrasound. The ultrasound is generated by an electric ultrasound generator.

Out DE 2841385 A1 is the use of an ultrasonic vibrator in a burner for the purpose of dusting the liquid fuel known.

Out FR 2 910 826 A1 For example, a device for generating ultrasonic vibrations with a tubular element, an electroacoustic transducer with a pair of piezoelectric ceramics and an intermediate element between the transducer and the tubular element is known. The intermediate element is located on the distal surface of the transducer, where the tube element connects. The transducer is disposed in a sealed chamber in which circulates a cooling gas or liquid which is to be atomized.

In the DE 35 24 701 A1 The application of an ultrasonic atomizing nozzle for introducing diesel into an intake pipe is described. The ultrasonic nozzle has several spray openings.

From the DE 10 2008 031 404 A1 is the use of an ultrasonic field for nebulization of a reducing agent known. In this case, the storage device is assigned an ultrasound device, by means of which fog can be generated. In addition to this, the spraying is provided by means of pressure in the exhaust system.

The object of the invention is to design and arrange a system provided with a nebulising device in such a way that, when a reducing agent such as a urea-water solution is used, the continuous load capacity is optimized at higher temperatures.

The object is achieved according to the invention in that the nebulization device has a sonotrode, wherein the sonotrode is formed from an ultrasonic generator and coupled thereto, a body forming mass and a lance with a channel in which a medium to be atomized can be transported, wherein the nebulizer at least with a part of the lance is arranged in the exhaust gas element and the medium to be atomized in the exhaust gas element is introduced nebulizable. The nebulization process is also based on a cavitation process, which causes a direct evaporation or atomization of the medium.

The atomization is carried out without the use of additional pressure medium such as compressed air or water vapor. The medium to be atomized is fed to the sonotrode via a supply line under pressure. For the determination of the pressure of the gas back pressure in the exhaust system is sufficient. At best, a slight overpressure is provided to account for pressure fluctuations in the gas back pressure.

The lance is preferably part of the mass that is excited by the ultrasonic generator. The lance can also be coupled to the mass.

By using a lance is achieved that only the part of the sonotrode, so the Lance or only part of the lance, must come into contact with the outlet end of the exhaust stream and the remaining part of the sonotrode or the nebulizer can be placed outside the exhaust pipe. Furthermore, only the channel of the lance is loaded with the agent to be nebulised, wherein the channel has only 2.4 mm in diameter or width. In particular, at the temperatures prevailing in the exhaust gas of about 350 ° C to 500 ° C is expected in the use of diesel as a hydrocarbon with a coking of the hydrocarbon-carrying elements. This particular for small diesel-conducting cross sections as the above-mentioned channel of the lance. During development it has been shown that this is reduced to a very good level by the use of a sonotrode due to the ultrasonic movement. The same applies to the use of reducing agents such as a urea-water solution for the aftertreatment of exhaust gases in an SCR catalyst. The associated deposits are also limited to a very good level by using a sonotrode. The areas affected by the coking or deposits are limited to the lance when using a sonotrode with a medium-guiding lance. Thus, further deposits in other areas of the sonotrode, which have a lasting effect on the service life or functionality of the nebulizer prevented. A separate supply of compressed air or other pressure aids for nebulization is not necessary.

Depending on the design of the lance, the sonotrode additionally has a supply line, via which a medium to be atomized is supplied to the sonotrode. The supply line is connected to the lance or its mass.

The object is also achieved by the use of a nebuliser with an electric sonotrode for atomizing reducing agent, such as UREA or diesel or other liquid hydrocarbons. The electric sonotrode has a piezoelectric drive which generates the ultrasonic vibration.

It may be advantageous for this purpose if coolant and / or insulation means are provided, by means of which the sonotrode is cooled and / or isolated. It has been shown that the atomization power of the sonotrode is significantly improved at lower temperatures for diesel and reducing agent.

In addition, it may also be advantageous if the lance in the region of an outlet end has a mass which is provided in addition to the tubular basic shape of the lance. The mass at the end of the lance promotes the oscillation behavior of the lance, hence the total atomization properties. The additional mass may be formed by an extension of the outer diameter of the lance at the end of the lance by 20% to 200%, for example. From 6 mm to 10 mm. In this case, conical, part-spherical or cuboid basic shapes are provided for the mass. The supplemental mass extends over a length of 5% to 30% or 10% to 15% of the lance length.

It may also be advantageous if the lance is at least partially inclined or horizontally extending with respect to the conveying direction. The fact that the supply line is arranged further up, a continuous distribution of the medium forms within the lance or of the channel. This is particularly advantageous in diesel and UREA, because these media could easily run out of the lance with the sonotrode in the opposite direction to the actual conveying direction of gravity. This would adversely affect the fogging properties.

Furthermore, it may be advantageous if the lance is arranged relative to the horizontal at an angle α between 0 ° and 180 °, between 5 ° and 175 °, between 80 ° and 100 ° or of 90 °. This angular range has proved to be particularly advantageous. In principle, an arrangement in the entire angular range of 360 ° is possible.

It may also be advantageous if the lance, starting from the main body up to an outlet end, has a length a1 which ensures insertion of the lance into the exhaust gas element. The length a1 of the lance is chosen such that the lance can be placed in relation to the outlet end in different regions of the exhaust gas flow. In the region of a pipe wall or exhaust wall, that is to say in an edge zone of the flow, in a center of the exhaust gas-carrying exhaust gas element, ie in the center of the flow or between these two positions. As already stated, a comprehensive arrangement of the nebulizer within the gas stream is disadvantageous. This leads to increased pollution of the nebulizer overall. In addition, the gas flow is adversely affected.

It may advantageously be provided that the lance or the channel has a line diameter D1 and at the outlet end has a taper with a diameter D2, which is smaller than the diameter D1.

Of importance may be for the present invention, when the lance has a diameter D1 between 1 mm and 4 mm or between 1.5 mm and 2.5 mm or 2.4 mm or 1.6 mm. This ensures a very good fogging effect, especially for diesel fuel and UREA. In the Selection of the diameter D1 is the density of the medium and the delivery rate of relevance.

It can also be advantageous if the part of the exhaust system is an oxidation catalytic converter, a catalytically coated diesel particulate filter, an SCR catalytic converter, an LNT catalytic converter or a mixer. For the purpose of regeneration of the particulate filter, diesel is supplied as an oxidizing agent via the nebuliser. The SCR catalytic converter (SCR = Selective Catalytic Reduction) and the LNT catalytic converter (LNT = Lean NOx Trap) are used for post-treatment of the exhaust gas to reduce the nitrogen oxide content.

Moreover, it may be advantageous if the distance b between the oscillating mass of the ultrasonic generator and the exit end of the lance is an integral multiple of half the wavelength of the ultrasonic wave generated by the ultrasonic generator.

Further advantages and details of the invention are explained in the patent claims and in the description and illustrated in the figures. It shows:

1 a schematic sectional view of the atomizer;

2 a schematic sectional view of the system consisting of nebulizer and exhaust element.

A nebuliser 2 to 1 is formed of a housing 2.1 in which an electric sonotrode 5 about storage, damping and sealants 2.7 is arranged. The sonotrode 5 consists essentially of an ultrasonic generator 5.1 and one to the ultrasonic generator 5.1 coupled mass 5.2 , which forms the basic body, so to speak. To the mass then forward extends a lance 2.2 with a channel 2.4 with an inner tube diameter D1, which is in the region of an outlet end 2.5 a rejuvenation 2.3 having a tapered pipe diameter D2. At the exit end 2.5 is a complementary mass in the form of a broadened lance tip 2.6 intended. As an alternative to the cone-shaped basic shape shown here, part-spherical or cuboid basic shapes are provided.

At the rear end of the sonotrode 5 is a supply line 6 intended for the medium to be atomized. Through the feed line 6 becomes the medium to be atomized of the sonotrode 5 or the channel 2.4 fed, the medium then after flowing through the channel 2.4 within the lance 2.2 Due to the ultrasonic movement, it is atomised at the outlet end 2.5 exit. For the purpose of supplying electric power, the sonotrode 5 an electrical connection 5.3 on.

The exit end 2.5 the lance 2.2 points to the end of the mass 5.2 a distance b which corresponds to an integer multiple of half the wavelength of the applied ultrasonic frequency, so that at the exit end 2.5 in a corresponding manner forms a wave belly of the superimposed, standing ultrasonic wave. In addition, the exit end has 2.5 to the housing 2.1 a distance a1 over which it is after 2 in an exhaust element 3 is insertable.

To 2 is the nebulizer 2 at least with the lance 2.2 within the exhaust element 3 arranged. In the sectional illustration shown here is within the exhaust element 3 a diesel particulate filter 4 to recognize, in the flow direction of the exhaust element 3 followed.

This is the lance 2.2 via an opening, not shown, of the exhaust element 3 or the pipe wall inserted or inserted and immersed over a length a2 radially into this. The exhaust element 3 in this case has a wall thickness c, so that the lance 2.2 over the length a2, which is the difference of the length a1 minus the wall thickness c of the exhaust element 3 corresponds, is introduced.

When growing according to 2 it is possible, the immersion depth a2 of the nebulizer 2 to vary.

While here the immersion depth between 40% and 60% of the diameter d of the exhaust element 3 is, it is provided in an embodiment, not shown, to reduce the immersion depth to 10% to 20% of said diameter d. For this purpose, either a nebuliser 2 with clearly shortened lance 2.2 , so be used with lance of smaller length a1. Alternatively, the nebulizer 2 be attached radially offset accordingly outward, so that the lance 2.2 with the length a1 only just above a said proportion in the exhaust element 3 dips.

After embodiment 2 is an isolation agent 8th between the exhaust pipe 3 and the sonotrode 5 intended. In addition, there are coolants 7 provided in which the sonotrode 5 is embedded.

LIST OF REFERENCE NUMBERS

1

system

2

atomizer

2.1

casing

2.2

lance

2.3

rejuvenation

2.4

channel

2.5

exit end

2.6

Mass, lance tip

2.7

Bearing, damping and sealant

3

Exhaust element, exhaust pipe

4

SCR catalytic converter, diesel particulate filter

5

sonotrode

5.1

ultrasonic generator

5.2

Mass, basic body

5.3

electrical connection

6

feed

7

coolant

8th

insulation materials

a1

Length, distance

a2

Length, immersion depth

b

distance

c

Wall thickness of 3

d

diameter of 3

D1

diameter

D2

diameter

Claims (10)

System ( 1 ) consisting of a misting device ( 2 ) and at least one exhaust gas-carrying exhaust element ( 3 ) as part of an exhaust system of an internal combustion engine, characterized in that the nebulizer device ( 2 ) a sonotrode ( 5 ), wherein the sonotrode ( 5 ) is formed from an ultrasonic generator ( 5.1 ) and a mass coupled thereto ( 5.2 ) and a lance ( 2.2 ) with a channel ( 2.4 ), in which a medium to be atomized can be transported, wherein the atomizing device ( 2 ) at least with a part of the lance ( 2.2 ) in the exhaust element ( 3 ) is arranged and the medium to be atomized in the exhaust element ( 3 ) is nebulised einbringbar. System according to claim 1, characterized in that coolant ( 7 ) and / or isolation means ( 8th ) are provided, by means of which the sonotrode ( 5 ) is cooled and / or isolated. System according to claim 1 or 2, characterized in that the lance ( 2.2 ) in the region of an exit end ( 2.5 ) a mass ( 2.6 ), which in addition to the tubular basic shape of the lance ( 2.2 ) is provided. System according to claim 1, 2 or 3, characterized in that the lance ( 2.2 ) is arranged at least partially inclined or horizontally extending with respect to the conveying direction. System according to claim 4, characterized in that the lance ( 2.2 ) is arranged with respect to the horizontal at an angle α between 0 ° and 180 °, between 5 ° and 175 °, between 80 ° and 100 ° or of 90 °. System according to one of the preceding claims, characterized in that the lance ( 2.2 ) starting from the main body to an exit end ( 2.5 ) has a length a1 which is an insertion of the lance ( 2.2 ) in the exhaust element ( 3 ) guaranteed. System according to one of the preceding claims, characterized in that the lance ( 2.2 ) has a line diameter D1 and at the exit end ( 2.5 ) a rejuvenation ( 2.3 ) having a diameter D2 smaller than the diameter D1. System according to one of the preceding claims, characterized in that the lance ( 2.2 ) has a diameter D1 between 1 mm and 4 mm or between 1.5 mm and 2.5 mm or 2.4 mm or 1.6 mm. System according to one of the preceding claims, characterized in that it is in the part of the exhaust system to an oxidation catalyst ( 4 ), an SCR catalyst ( 4 ), an LNT catalyst, a diesel particulate filter or a mixer. Use of a fogging device ( 2 ) with an electric sonotrode ( 5 ) according to one of the preceding claims for atomizing reducing agent or diesel or other liquid hydrocarbons.

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