Device for providing a liquid additive

Abstract

Device (1) for providing a liquid additive (2) for exhaust gas purification, comprising at least one channel (3) for conveying the liquid additive with a channel wall (4), wherein an insert component (5) is inserted into the channel (3), which extends at least sectionally along the channel (3), wherein the insert component (5) consists of a solid material.

Description

The invention relates to a device for providing a liquid additive for exhaust gas purification. Such a device can be used in particular to supply a liquid additive (in particular urea-water solution) to an exhaust gas treatment device of a motor vehicle.Liquid additives are required, for example, in exhaust gas treatment devices in which nitrogen compounds in the exhaust gas are reduced with the aid of a reducing agent. In such exhaust gas treatment devices, the selective catalytic reduction (SCR) method is carried out. In the SCR method, ammonia is used as the reducing agent. Ammonia is often not stored directly in motor vehicles, but rather in the form of a liquid additive which can be converted to ammonia internally (in the exhaust gas treatment device) and / or externally (in a reactor provided for this purpose). A liquid additive which is particularly frequently used for the SCR method is urea-water solution which is available with a urea content of 32.5% under the trade name AdBlue®.DE 10 2011 102 170 A1 discloses an injection device for injecting a fluid into an exhaust gas treatment device, wherein the injection device has an injector which is positioned in an injector holder, wherein the injector has an inlet opening and a component of the injector holder extends into the inlet opening. Such an injection device is suitable in particular for the supply of urea-water solution into the exhaust gas treatment device of a motor vehicle.DE 11 2006 002 122 B4 discloses a metering valve assembly for dispensing a reducing agent into an exhaust gas flow in an exhaust manifold of an internal combustion engine, comprising: a control valve coupled to a reducing agent source, wherein the control valve is an electronically controlled injection nozzle, a reducing agent dispensing valve constructed and arranged to be coupled to the exhaust manifold in order that a predefined amount of reducing agent can be dispensed into the exhaust gas flow, wherein the reducing agent dispensing valve has an inlet which is connected to an extended line which is located between the control valve and the reducing agent dispensing valve and conducts reducing agent from the control valve to the reducing agent dispensing valve, wherein the reductant dispensing valve is coupled to the exhaust manifold and the control valve is displaced away from the reductant dispensing valve.When designing such devices, it should be noted that the liquid or aqueous additive can freeze at low temperatures. A urea-water solution freezes at a temperature of about -11 °C. Such low temperatures can occur in motor vehicles, especially during longer idle times in winter. Upon freezing, the liquid additive expands, and the device for supplying the liquid additive may thus be damaged or even destroyed. The volume expansion during freezing can deform or even break up channels of such a device. It is known for this reason to provide protective measures on such a device which prevent damage and / or destruction of the device as far as possible. For example, flexible or deformable elements are known which are arranged in the channels of a device and which can absorb a volume expansion during freezing. However, it is problematic that such protective measures often have a low durability and can nevertheless be damaged by repeated or repeated freezing of the liquid additive.Proceeding from this, it is an object of the present invention to solve or at least alleviate the technical problems described. In particular, a device for providing a liquid additive with a technically simple, cost-effective, effective, retrofittable and / or permanent freeze protection measure is to be specified.These objects are achieved with a device according to the features of claim 1. Further advantageous embodiments of the device are specified in the dependent claims. The features individually listed in the patent claims can be combined with one another in any desired, technologically meaningful manner and can be supplemented by explanatory facts from the description, in particular also the description of the figures.The invention relates to a device for providing a liquid additive for exhaust gas purification, having at least one channel for conducting the liquid additive with a channel wall, wherein an insert component is inserted into the channel, which insert component extends along the channel, wherein the insert component consists of a solid material.The channel is preferably part of a channel system of the device. The device for supplying liquid additive preferably has a pump arranged on / in the channel system, with which pump the liquid additive can be conveyed along or through the channel system. The channel system opens at an intake point on a tank for storing the liquid additive and preferably leads to a connection at which the liquid additive can be provided (outside the tank). The channel may be any portion of this channel system. The channel can be formed, for example, with a hose, a bore and / or another cavity. The channel can in particular also be formed in a base plate of the device, which serves for the mounting of components of the device. The channel can also be formed in various ways in sections. For example, the channel can be formed partly by a hose and partly by a base plate. Components through which the channel runs can also be referred to as channel components. The channel system or the channel can also have branches. For example, it is possible for the channel system to comprise a return line which branches off from a main branch of the channel and leads back into the tank, and by means of which a circulation of liquid additive from the tank, into the channel and back into the tank is possible. The material of a channel component which directly delimits the channel is also referred to as a channel wall. The channel wall can be formed, for example, with the material of a (plastic) hose or the material of a (metallic) base plate.The insert component is a component (separate and optionally movable in the channel) which is inserted into the channel. The insert component is preferably rod-shaped and extends along (a sub-sector) the course of the channel. The relative volume increase during freezing of the liquid additive decreases as a result of the insert component, so that a technically simple, cost-effective, effective, retrofittable and permanent freeze protection measure is provided.The insert component consists of a solid material. The insert component in particular does not have any integrated cavities in which a compressible medium is located. The term "solid material" also includes, for example, solid materials or completely solid materials. The term "solid material" does not include in particular the following materials:foam materials,porous materials, andmaterials having at least one chamber which can be filled with a compressible medium, in particular with air.Due to the fact that the insert component consists of a solid material, it behaves substantially incompressible even at very high pressures in the channel. By very high pressure is meant here pressures above the maximum operating pressure of a device. The maximum operating pressure is, for example, between 5 bar and 10 bar. Very high pressures are in particular pressures in the range of the maximum possible ice pressure which can occur within the device when the liquid additive freezes. The maximum possible ice pressure is, for example, between 20 bar and 50 bar. At very high pressures, compression of the solid material may occur. However, this compression is negligibly small. Negligible compression corresponds here to a volume reduction of the insert component of less than 2 percent, in particular less than 1 percent. Preferably, when the pressure in the channel increases from 1 bar to more than 20 bar, only a volume reduction of the insert component by less than 2 percent, preferably less than 1 percent, occurs. The compression of a solid material at very high pressures is negligible in particular compared to the compression of a component made of the same material which is porous or which (as described further above) has at least one fillable chamber which is filled with a compressible medium. In the case of a porous material or a material with fillable chambers, a deformation occurs in particular because the at least one chamber or the pores are compressed. In contrast, in the case of a solid material, it is necessary for the material to be compressed in itself. For compressing the material in itself, considerably higher pressures are usually necessary. Even materials which have a very high compressibility as foam behave substantially incompressible as solid material when used for an insert component in the channel of a described device.Furthermore, the device is advantageous if a first cross-sectional area of the channel and a second cross-sectional area of the insert component are round.The insert member is preferably a (substantially) round rod extending along (a sub-sector) of the channel. By using an insert component with a round cross-sectional area and a channel with a round cross-sectional area, a substantially annular gap exists between the insert component and the channel, which gap runs around the insert component, or optionally also an approximately crescent-shaped gap, which gap runs at least in sections around the insert component. It has been found that such a shaped gap is particularly favorable in order to cause a lower stress in the channel wall as a result of the volume expansion of the liquid additive during freezing compared to known measures. In particular, the volume expansion of the liquid additive is distributed uniformly over the entire channel wall, so that stress peaks, which could be caused by a locally greatly increased volume expansion, are reliably reduced by the insert component.Furthermore, the device is advantageous if a gap through which flow can pass exists between the channel wall and the insert component, which gap surrounds the insert component by at least 270° [angle degree].Particularly preferably, the gap surrounds the insert component even for at least 330° (as viewed in cross section and in the circumferential direction of the insert component) and very particularly preferably even completely (360°). The volume expansion of the liquid additive during freezing can then be distributed particularly uniformly over the entire circumference of the insert component and the stresses occurring during freezing in the duct wall can be reduced particularly effectively.Furthermore, the device is advantageous if a second cross-sectional area of the insert component fills at least 30% of a first cross-sectional area of the channel. Particularly preferably, the second cross-sectional area of the insert component fills up even 50% and very particularly preferably 60% of a first cross-sectional area of the channel.By such a ratio of the second cross-sectional area to the first cross-sectional area, it can be ensured that the remaining residual cross-sectional area of the gap through which flow can take place is so small that the quantity of liquid additive present there cannot cause a volume expansion which is critical for the channel wall.It is also advantageous if the insert component consists of at least one of the following materials:a metal,a ceramic, anda plastic which is resistant to liquid additive.These materials mentioned are available simply and cost-effectively in order to provide an insert component made of a solid material. Preferably, particularly light materials are used. Due to the fact that the material is used as a solid material, heavy materials would increase the weight of the device too much. The metal can be, for example, aluminum, which is corrosion-resistant (in particular to urea-water solution) due to a passivating layer of aluminum oxide (Al 2 O 3). Aluminum is a particularly light metal. Suitable ceramics are, for example, zirconium oxide (ZrO 2) or aluminum oxide (Al 2 O 3) because both materials are relatively light and resistant to the known liquid additives. For example, polyoxylmethylene (POM), polyamide (PA), in particular PA 6.6 (nylon), polyphthalamide (PPA) or polyphenylene sulfide (PPS) can be used as the plastic material.Furthermore, the device is advantageous if the channel wall is manufactured using an injection molding process. With an injection molding method, channels of a device for providing liquid additive can be manufactured particularly easily and cost-effectively, and the plastics mentioned further above are suitable for processing with an injection molding method.Furthermore, a motor vehicle is proposed, having an internal combustion engine, an exhaust gas treatment device for purifying the exhaust gases of the internal combustion engine, and a described device, with which a liquid additive can be provided to the exhaust gas treatment device. In the exhaust gas treatment device, an SCR catalyst is preferably provided, with which nitrogen oxide compounds in the exhaust gas of the internal combustion engine can be reduced according to the SCR method. For this purpose, a liquid additive can be supplied to the exhaust gas treatment device via a device described, which additive is removed from a tank by the device.The invention and the technical field are explained in more detail below with reference to the figures. The figures show particularly preferred exemplary embodiments, to which the invention is, however, not limited. In particular, it should be pointed out that the figures and above all the size relationships illustrated in the figures are only schematic. The following are shown: FIG. 1 shows a first embodiment variant of a described device, FIG. 2 shows a cross section through a channel of the described device from FIG. 1, FIG. 3 shows a second embodiment variant of a described device, FIG. 4 shows a cross section through a channel of the described device from FIG. 3, FIG. 5 shows a motor vehicle having a described device.Fig. 1 shows an apparatus 1 inserted into a bottom 22 of a tank 13. The device 1 removes liquid additive 2 from the tank 13 at an intake point 20 and provides it at a supply connection 21. The supply connection 21 and the intake point 20 are connected to one another by a channel 3. A pump 14 for conveying the liquid additive 2 is located on the channel 3, the channel 3 being bounded in sections by a channel wall 4. This channel wall 4 is formed by a channel component 19. This channel component 19 can be, for example, a hose, a base plate or any other component which forms a section of the channel wall 4 of the channel 3. An elongated insertion component 5 is inserted into the channel 3, which extends in sections along the channel 3.The channel 3 with the channel wall 4 and the insert component 5 is shown in cross section in FIG. 2. The first cross-sectional area 6 of the channel 3 and the second cross-sectional area 7 of the insert component 5 can be seen. A crescent-shaped gap 8 is produced between the insert component 5 and the channel wall 4, in this case, through which the liquid additive can flow. The insert component 5 and the channel 3 each have round cross sections with a first diameter 17 and a second diameter 18, respectively.FIGS. 3 and 4 show a further variant embodiment of a device 1, which corresponds substantially to the device 1 from FIGS. 1 and 2. It can be seen in FIG. 4 that the insert component 5 is arranged here concentrically in the channel 3. In order to hold the insert component 5 there, the channel 3 or the channel wall 4 has a receptacle 23, in which at least one end of the insert component 5 is held. Such receptacles 23 can also be provided for both ends of the insert component 5. It can also be seen in FIG. 4 that the gap 8 between the channel wall 4 and the insert component 5 is not crescent-shaped here. Rather, the gap 8 is annular and surrounds the insert component 5 by 360°.FIG. 5 shows a motor vehicle 9, having an internal combustion engine 10 and an exhaust gas treatment device 11 for purifying the exhaust gases of the internal combustion engine 10. For this purpose, a liquid additive can be supplied to the exhaust gas treatment device 11 by means of an addition device 16. The addition device 16 is supplied with liquid additive from a tank 15 via a device 1.It should be mentioned as a precautionary measure that the combinations of technical features shown in the figures are not generally obligatory. Technical features of a figure can thus be combined with other technical features of a further figure and / or the general description. Something else is intended to apply only if the combination of features has been explicitly specified here and / or the person skilled in the art recognizes that otherwise the basic functions of the apparatus or of the method can no longer be fulfilled.The device 1 for providing a liquid additive is accordingly designed with a technically simple, cost-effective, effective, retrofittable and permanent anti-freeze measure.List of reference characters1 Device 2 Liquid additive 3 Channel 4 Channel wall 5 Insert component 6 First cross-sectional area 7 Second cross-sectional area 8 Gap 9 Motor vehicle 10 Internal combustion engine 11 Exhaust gas treatment device 12 SCR catalytic converter 13 Tank 14 Pump 15 Tank 16 Addition device 17 First diameter 18 Second diameter 19 Channel component 20 Intake point 21 Supply connection 22 Base 23 Receptacle

Claims

Device (1) for providing a liquid additive (2) for exhaust gas purification, having at least one channel (3) for conducting the liquid additive with a channel wall (4), wherein an insert component (5) is inserted into the channel (3), which insert component extends at least in sections along the channel (3), wherein the insert component (5) consists of a solid material.The device (1) according to claim 1, wherein a first cross-sectional area (6) of the channel (3) and a second cross-sectional area (7) of the insert component (5) are round.Device (1) according to one of the preceding patent claims, wherein a gap (8) through which flow can pass exists between the channel wall (4) and the insert component (5), said gap surrounding the insert component (5) by at least 270°.Device (1) according to one of the preceding patent claims, wherein a second cross-sectional area (7) of the insert component (5) fills at least 30% of a first cross-sectional area (6) of the channel (3).Device (1) according to one of the preceding patent claims, wherein the insert component (5) consists of at least one of the following materials: - a metal, - a ceramic, and - a plastic which is resistant to liquid additive.Device (1) according to claim 5, wherein the channel wall (4) is manufactured by an injection molding process.Device (1) according to one of the preceding claims, wherein the insert component (5) has a thermal expansion of more than 100 μm / mK [micrometers per meter and Kelvin] in the temperature range between -30°C and +50°C.Motor vehicle (9), comprising an internal combustion engine (10), an exhaust gas treatment device (11) for cleaning the exhaust gases of the internal combustion engine (10), and a device (1) according to one of the preceding patent claims, with which a liquid additive can be provided to the exhaust gas treatment device (11).

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