EP2710242A1

EP2710242A1 - Injection device for injecting a fluid

Info

Publication number: EP2710242A1
Application number: EP12722722.1A
Authority: EP
Inventors: Jan Hodgson; Sven Schepers
Original assignee: Emitec Gesellschaft fuer Emissionstechnologie mbH
Current assignee: Continental Automotive GmbH
Priority date: 2011-05-20
Filing date: 2012-05-18
Publication date: 2014-03-26
Also published as: WO2012159986A1; CN103620174A; DE102011102170B4; RU2606721C2; KR20130140871A; CN103620174B; JP2014519572A; JP6067000B2; RU2013156471A; DE102011102170A1; US20140075923A1; US9334780B2; KR101503206B1

Abstract

Injection device (1) for injecting a fluid into an exhaust-gas treatment device (15), having an injector (2) which is positioned in an injector holder (3), wherein the injector (2) has a feed opening (4) and a component (5) of the injector holder (3) extends into the feed opening (4). An injection device (1) of this type is suitable, in particular, for feeding urea/water solution into the exhaust-gas treatment device (15) of a motor vehicle. The component (5) is preferably rigid in the longitudinal direction (23) and can be compressed in the radial direction (24) by way of a deformable rubber shell, in order to compensate for the volumetric expansion of the solution if it freezes.

Description

Injection device for injecting a fluid

The invention relates to an injector for injecting a fluid into an exhaust treatment device, comprising an injector positioned in an injector holder.

It is known to selectively supply a fluid to an exhaust gas treatment device for purifying exhaust gases of an internal combustion engine in order, for example, to realize a chemical conversion of exhaust gas constituents. Such a fluid is, for example, an oxidizing agent or a reducing agent. As a fluid is in particular a urea-water solution into consideration. A particularly commonly used for the reduction of harmful nitrogen oxide in the exhaust gas 32.5 percent urea-water solution is obtainable for example under the trade name AdBlue ^®. With such a urea-water solution, the method of selective catalytic reduction [SCR] can be performed in the exhaust gas treatment apparatus. The metering of the fluid can be done with such an injection device with an injector. An injector can be selectively opened or closed again in order to provide the fluid metered. In such injectors is regularly considered that the supplied fluid can form deposits. Such deposits are common in injectors, especially in the area of injectors. In this area, the flow path for the fluid to be supplied to the injector often has design-related deflections and extensions, which lead to deceleration and / or turbulence of the fluid to be supplied. This favors the formation of deposits. Furthermore occur on injectors regularly very large temperature fluctuations. This also increases the formation of deposits. In particular, when as urea fluid Water solution is used, increased temperatures (near the exhaust system) may already occur in the injector, a chemical change in the urea-water solution, which accelerates the formation of deposits. It should also be noted that the fluid can also freeze at low temperatures and then cause damage due to volume expansion and / or clog the injector.

On this basis, it is an object of the present invention, at least partially solve the problems described with reference to the prior art. In particular, an injection device is to be disclosed, which is technically simple and in which the functionality of the injector is improved with temperature fluctuations. These objects are achieved with an injection device according to the features of claim 1. Further advantageous embodiments of the injection device are specified in the dependent formulated claims. It should be noted that the features listed individually in the claims can be combined with each other in any technologically meaningful way, and show further embodiments of the invention. The description, in particular in conjunction with the figures, further explains the invention and provides additional embodiments. The invention accordingly relates to an injection device for injecting a fluid into an exhaust gas treatment device, comprising an injector positioned in an injector holder, the injector having an inlet opening and a component extending into the inlet opening.

The injection device described is particularly advantageous if the component is (at least) rigid in a longitudinal direction aligned parallel to the inlet opening and at least partially compressible in a direction radial to the longitudinal direction. The injection device is particularly suitable for injecting a fluid into an exhaust gas treatment device. In particular, the fluid is a reducing agent or a urea-water solution. Thus, in particular, an injection device for a urea-water solution in an exhaust pipe of an exhaust gas treatment device of a motor vehicle is proposed here.

On the one hand, the flow of the fluid into the injector can be accelerated through the component which extends into the inlet opening of the injector. In addition, the flow path or the flow into the injector can be made uniform. In addition, the (less) well-flowed areas can be better flown or flushed through the component, so that deposits are better avoided in this area. In addition, connection-induced or injector-related large volumes in the region of the inlet opening of the injector can be reduced, so that even in the case of temperature fluctuations (boiling and / or freezing) vapor bubbles, deposits and / or large ice pressures can be reduced or even avoided.

By the proposed injection device, an expansion of the fluid can be compensated particularly well. For example, the fluid (eg, urea-water solution) expands when it freezes. This is particularly problematic in the area of the injector of the injector, because the injector can be damaged by the increase in volume of the fluid.

The line system of an injection device (ie in particular the volume of the injection device filled with fluid) should preferably be as rigid as possible in order to achieve a high dosing accuracy of the injection device. This is because pressure fluctuations in operation affect the volume of the piping system less, the more rigid the piping system is. For a special good compensation of the expansion of the fluid during freezing, a great flexibility of the piping system is advantageous. The greater the flexibility, the smaller are the pressures encountered during expansion during ice formation, and the lower is the risk of damaging the injector (and in particular the injector) during freezing.

It has been found that a particularly effective compensation of the expansion of the fluid during freezing in the region of the injection device with a particularly low compressibility of the conduit system (or the fluid-filled volume) is possible by the described component. An expansion of the reducing agent is particularly critical here because this expansion could be derived in the direction of the inlet opening (in the longitudinal direction) into a feed channel to the injection device. Therefore, it is advantageous to provide in the inlet opening a component which has a compressibility especially for the compensation of the expansion in a radial direction perpendicular to the longitudinal direction of the inlet opening. This (essentially only radial) compressibility can be achieved, for example, by a displacement and / or deformation of the component laterally to the inlet channel. For this could possibly be used in the component prepared spaces to create a (reversible) replacement space for the ice during a freezing process. In particular, components of the component and / or the component can deform and / or compress itself when ice pressure occurs.

The injection device is also advantageous if the component is formed by at least one insert which is arranged together with the injector in the injector holder.

Such an insert may be provided in the injector holder to hold the injector in position. The insert preferably forms a component of a supply channel to the injector. The supply channel is regularly connected via further line sections to a fluid delivery unit and to a tank for the fluid.

The injection device is also advantageous if the insert has a supply channel which leads to the component and the inlet opening and extends through the injector holder.

The component which extends into the inlet opening of the injector is preferably designed in such a way that in the region of the inlet opening of the injector there is a cross-section through which the reducing agent can pass, which essentially corresponds to the cross-section of the supply channel.

Further advantageous is the injection device when the component comprises a tube. The tube may, for example, form a continuation of a supply channel to the injector. Such a tube forms a particularly effective homogenization of the flow path into the injector. Preferably, this tube has an inner cross-section, which corresponds approximately to an inner channel of the injector to the inlet opening. Furthermore, the injection device is advantageous if the component has at least one perforation. In this embodiment, the component is preferably designed as a tube which has a tube wall. The perforation (in other words, a plurality of through holes, holes, etc.) is provided in this pipe wall. Preferably, the tube has a uniform perforation, which is evenly distributed over the entire component and which consists of a plurality of openings. Due to the perforation, the surface and the volume of the tube wall are preferably reduced by at least 20%, wherein the area and the volume should more preferably not be reduced more than 50%.

Furthermore, it is proposed that the component is surrounded by at least one rubber jacket. The rubber jacket prevents the formation of deposits further. Already the surface of the rubber jacket prevents a permanent connection of deposits. Moreover, the rubber jacket is elastic and changes in volume and shape as the pressure of the fluid in the supply passage fluctuates. The rubber jacket can be vulcanized on the component, for example. The rubber jacket is preferably made of a compressible and / or compressible material. A rubber jacket ensures that the component is at least partially compressible in the radial direction. The rubber jacket can be understood in particular as part of the component. The component is then preferably designed in several parts and has a (preferably rigid) core and the surrounding, flexible rubber sheath.

The component may further have a roughened surface in the region of the rubber jacket. On such a surface a vulcanised rubber coat keeps very well. The roughened surface preferably has an (average) roughness RZ of between 5 μm [microns] and 15 μm [microns]. In a further variant, the rubber jacket can also be shrunk onto the component. The rubber jacket can for example be placed on the component in the manner of a shrink tube. After the rubber tube designed as a shrink tubing is placed on the component, the shrink tube is activated by a special change in the environmental conditions and shrinks. A change in the environmental conditions may be, for example, a short-term increase in the ambient temperature. Due to the shrinkage, the shrink tube or the rubber jacket then fits tightly against the component. Preferably, the surface of the component and the shrink tube is designed such that a high coefficient of friction between the component and the rubber sheath exists. The coefficient of friction is preferably greater than 0.6 and more preferably even greater than 0.8. The friction coefficient defines the ratio between the shear stress that can be transmitted between the rubber jacket and the component and the normal stress that acts between the rubber jacket and the component. The normal stress is in this case essentially determined by the force exerted by the shrinkage tube during shrinkage on the component. The larger this coefficient of friction, the more tight the rubber jacket sits on the component and the lower the risk that the rubber jacket shifts on the component.

Since such a rubber jacket can be formed separately, for example, on an inner side and an outer side of the tube, it is also possible to provide a plurality of (different) rubber sheaths in one component.

For example, the rubber jacket can be structured on the outside of a pipe-designed component in such a way that the formation of deposits of reducing agents is effectively avoided. For this purpose, the rubber jacket on the outside, for example, be hydrophobic, so that urea-water solution there rolls off the rubber jacket.

On the inside of a pipe designed as a component regularly takes place with a flow of reducing agent, so that deposits here are not as problematic as on the outside, where often are not regularly flowed through with fresh reducing agent areas. Thus, the rubber jacket can preferably be configured here so that the friction of the flowing reducing agent on the rubber jacket is particularly low and the component thus has a particularly low flow resistance. The rubber jacket has on the inside of the tube designed as component preferably a particularly low roughness. For example, the inside surface of the rubber mantle has an average roughness RZ of less than 2 μm [microns], preferably less than 1 μm [microns].

The component is preferably made of a material which is substantially rigid compared to the rubber jacket. This ensures that the basic shape of the component - for example the shape of a pipe with a pipe wall - does not deform when the pressure of the fluid in the supply duct fluctuates.

The rubber jacket can seal the component in the inlet opening of the injector. The rubber jacket can be designed so that the component can be positively inserted into the inlet opening and the connection between the component and the inlet opening is sealed. The rubber jacket can be compressed in the region of the contact between the component and the inlet opening (slightly) so that the rubber jacket rests under prestress against the wall of the inlet opening.

In a further preferred embodiment, the component has a rubber jacket and a perforation, wherein the rubber jacket at least partially covers the perforation. The (at least one) rubber sheath may then deform into the perforation when the pressure of the fluid in the supply passage is greatly increased. This may occur, for example, when the fluid freezes in the supply duct. Such a configuration is particularly advantageous and inexpensive to achieve with a rubber jacket, which is applied as a shrink tube on the component. Such a rubber jacket can easily extend over the perforation, without the perforation is completely covered by the rubber jacket.

By combining a rubber jacket with a perforation of the component can also be a particularly effective freeze protection for the injection device can be realized. As the fluid in the injector freezes, the rubber sheath may deform into the perforation to compensate for the volume expansion of the fluid upon freezing.

Preferably, a combination of rubber sheath and perforation is set so that the rubber sheath deforms significantly only in the perforation at a pressure which is above the usual operating pressure. This can be achieved inter alia by a suitable choice of the following parameters:

Size of the individual openings of the perforation;

Thickness of the rubber jacket;

Elastic modulus of the rubber jacket; and

Tension of the rubber jacket over the openings of the perforation.

The rubber jacket is preferably designed so that a maximum increase in volume of a maximum of 100 μΐ [microliters], preferably a maximum of 50 μΐ [microliters] and more preferably a maximum of 10 μΐ [microliters] occurs by a deformation of the rubber jacket at a pressure below a threshold pressure. The threshold pressure is z. B. in a range between 3 and 10 bar. At pressures above the threshold pressure, a volume increase of more than 50 μΙ / bar [microliter / bar], preferably more than 100 μΐ / bar [microliter / bar], preferably occurs as a function of the further pressure increase. Thus, it can be ensured that the volume filled with reducing agent is approximately constant during regular operation, while a strong increase in volume is possible when freezing the reducing agent.

In one embodiment of the injection device, the component is made of a flexible material. The component may in particular be a tube made of a flexible material. The component may for example consist at least partially or even completely of a material with pores, whose pores are closed and filled with a compressible gas (for example air). The fluid preferably can not penetrate into the pores. As the pressure in the injector increases, the gas in the pores can be compressed. The component can thus be compressed and is accordingly compressible. Optionally, at least one stiffening structure can also be provided in the component (or tube). This stiffening structure can prevent the component from being compressible in the longitudinal direction. The stiffening structure preferably has no influence on the compressibility of the component in the radial direction.

It is preferred that the component is designed to be stiffer in the longitudinal direction than in the radial direction at least in a section lateral to the inlet channel, in particular near or adjacent to the injector. In particular, a directed in the longitudinal direction of ice pressure in the injector or in the inlet channel causes a shift of the component as a whole. In contrast, a directed in the radial direction of ice pressure in the injector or in the inlet channel causes a (locally limited, near the inlet opening arranged) deformation / compression of the component.

Further, it is considered advantageous if the component is designed to supply the fluid accelerated to the injector. The component can also narrow the supply duct. As a result, an acceleration of the flow in the region of the injector is achieved. Thus, the prevention of deposits can be further improved.

In addition, it is proposed that the inlet opening has a first cross-sectional area, and the first cross-sectional area is filled by the component to at least 40%. The cross-sectional area is preferably filled to at least 50% and particularly preferably to at least 70%. Of course, in order to ensure a flow flow into the injector, the component can not cover the entire cross-sectional area, so that a filling level of at most 85% preferably should not be exceeded. This effectively reduces the fluid-filled volume in the area of the injector. Thereby, the formation of deposits can be avoided because an effective flushing with fluid and an acceleration of the fluid flow can be achieved.

It is considered advantageous if an ice pressure compensation element is provided on the injection device, which is designed to accommodate an expansion of the fluid in the longitudinal direction. The ice pressure compensating element is preferably arranged in the longitudinal direction opposite to the inlet opening. The Eisdruckkompensationselement is designed for example as an elastic bellows and / or flexible stopper, which can deform and / or move when (due to the freezing fluid) ice pressure occurs in the injector. An expansion of the fluid can be derived in the longitudinal direction from the inlet opening of the injector and be derived according to a particularly advantageous embodiment of an arranged outside the injector Eisdruckkompensationselement. The Eisdruckkompensationselement is preferably designed such that it behaves substantially rigidly in the operation of the injection device (at normal operating pressures) and at higher pressures, an additional volume free and absorbs an expansion of the fluid. The number and position of the Eisdruckkompensationselemente in an injection device can, for. B. adapted to the Eisblidungprozesse inside the injector.

Further advantageous is the injection device according to the invention, when the injector is clamped in the injector holder with a spring. By such a spring, the injector can be firmly positioned in the Injektorhalter and at the same time can be set to a seal for sealing the supply duct and the injector with the spring under bias, so that a secure seal is ensured. It is particularly advantageous if the injector together with an insert in the Injector holder is clamped, wherein the insert forms a supply channel.

With a tensioned in the injector holder injector can be provided on the injection device in a particularly advantageous manner, a Eisdruckkompensationselement. The component is preferably positioned between the spring and the injector. The component is then displaceable relative to the injector against a biasing force exerted by the spring. By a displacement of the component, an expansion in the longitudinal direction can be compensated. The biasing force exerted by the spring is preferably adjusted so that the component does not shift during operation of the injection device (at normal operating pressures). The invention finds particular application in a motor vehicle, comprising an internal combustion engine, a

Exhaust gas treatment device for cleaning the exhaust gases of the internal combustion engine, and an injection device according to the invention for supplying a fluid to the exhaust gas treatment device.

The invention will be explained in more detail with reference to FIGS. It should be noted that the figures show particularly preferred embodiments of the invention, to which the invention is not limited. In particular, it should be noted that the figures and in particular the illustrated proportions are only schematic table. Show it:

1: an injection device,

2 shows a detail of an injection device,

Fig. 3: a motor vehicle having various

Injectors, and 4 shows a further detail of an injection device.

1 shows an injection device 1 according to the invention which has an injector 2 which is arranged in an injector holder 3. The injector 2 has an electrical connection 18, in which control signals for opening and closing the injector 2 can be initiated. The injector 2 has an inlet opening 4 into which a component 5 of an insert 9 extends. The insert 9 is braced together with the injector 2 with a spring 11 in the injector holder 3. The spring 11 is preferably a plate spring. The upper portion of the injector holder 3 is formed by a cap 16. The insert 9 forms a feed channel 10, through which the fluid can pass into the injector 2 or into the inlet opening 4 of the injector 2.

The injector 2 and the insert 9 are sealed with an O-ring seal 17 from the environment.

Furthermore, an aligned parallel to the inlet opening 4 longitudinal direction 23 and a perpendicular thereto aligned radial direction 24 are shown for illustration.

In FIG. 2, the detail A marked in FIG. 1 is shown in greater detail. Evident here is the insert 9 and a portion of the injector 2, in which the inlet opening 4 is arranged. The component 5 of the insert 9 extends into the inlet opening 4. The insert 9 forms the supply channel 10, which serves to supply the fluid into the inlet opening 4. The component 5 is here designed as a (narrow) tube 6, wherein the tube wall 14 of the tube 6 has a perforation 7. The perforation 7 is preferably formed by a multiplicity of openings or recesses in the component 5 or in the tube wall 14. The component 5 or the tube wall 14 is surrounded by a vulcanized rubber jacket 22. The rubber sheath 22 preferably extends beyond the perforation 7. In the area of the component 5 shown on the right, it can be seen how the rubber jacket 22 deforms into the perforation 7 when the pressure in the supply channel 10 is increased.

The inlet opening 4 of the injector 2 has a first cross-sectional area 8. This first cross-sectional area 8 is at least partially filled by the tube 6 or the cross-sectional area of the tube wall 14 of the tube 6. The insert 9 and the injector 2 are sealed from the environment with the O-ring seal 17.

3 shows a motor vehicle 12 comprising an internal combustion engine 13 and an exhaust gas treatment device 15 for cleaning the exhaust gases of the internal combustion engine 13. In FIG. 3, two different injection devices 1 are indicated. A first injection device 1 is provided on the internal combustion engine 13 and serves, for example, for supplying fuel to the internal combustion engine 13. This injection device 1 is supplied with fuel from a fuel tank 20 for this purpose. A second injection device 1 is shown on the (exhaust pipe of) exhaust treatment device 15 and serves to supply a reducing agent into the exhaust treatment device 15, wherein with the reducing agent in a (not shown) SCR catalyst, a selective catalytic reduction of nitrogen oxide compounds in the exhaust gas of the internal combustion engine 13 is performed can be. This injection device 1 is supplied from a reducing agent tank 19 with reducing agent, wherein the needs-based operation of the injection device (s) 1 is controlled by a controller 21.

4, a further embodiment of the injection device is shown in detail. The matching with the Fig. 2 Details of FIG. 4th will not be explained again here, but reference is made to the description of this figure.

According to FIG. 4, a component 5 of the injector holder 3 likewise extends into the inlet opening 4 of the injector 2. The component 5 is also designed here as a tube 6. However, this tube 6 has no perforation, but is made of a flexible and / or compressible material. The tube 6 may for example consist of a material with pores 26 whose pores are closed and filled with a compressible gas (for example, air). The fluid may preferably not enter the pores 26. As the pressure in the injector increases, the gas in the pores 26 may be compressed. The component 5 can thus be compressed - ie reduce its own volume and this volume reduction can compensate for the ice expansion at least partially. Furthermore or alternatively, at least one stiffening structure 25 can be provided in the component 5 or the tube 6. This stiffening structure 25 can prevent the component 5 in the longitudinal direction 23 is compressible. The stiffening structure 25 preferably has no (significant) influence on the compressibility of the component 5 in the radial direction 24.

With regard to the description of the figures, it should be pointed out that the functions, modes of action and technical features illustrated there can also be applied to the invention as such and / or details of other figures. A person skilled in the art will readily appreciate upon studying the description that the functions, modes of action and / or technical details shown here for one figure can also be combined individually with those of other figures. Something else should only apply insofar as such a combination is explicitly excluded or technically impossible. LIST OF REFERENCE NUMBERS

1 injection device

2 injectors

3 injector holders

4 inlet opening

5 component

6 tube

7 perforation

8 first cross-sectional area

9 use

10 supply duct

11 spring

12 motor vehicle

13 internal combustion engine

14 pipe wall

15 exhaust treatment device

16 cap

17 O-ring seal

18 electrical connection

19 reducing agent tank

20 fuel tank

21 control

22 rubber coat

23 longitudinal direction

24 radial direction

25 stiffening structure

26 pore

Claims

claims

An injector (1) for injecting a fluid into an exhaust treatment device (15), comprising an injector (2) positioned in an injector holder (3), the injector

(2) has an inlet opening (4) and a component (5) of the injector holder (3) extends into the inlet opening (4)

2. Injection device (1) according to claim 1, wherein the component (5) in a parallel to the inlet opening (4) aligned

Longitudinal direction (23) is rigid and at least partially compressible in a radial direction (24) to the longitudinal direction (23).

3. Injection device (1) according to one of the preceding claims, wherein the component (5) of at least one

Rubber sheath (22) is surrounded.

4. Injection device (1) according to one of the preceding claims, wherein the component (5) has a rubber jacket (22) and a perforation (7), and wherein the rubber jacket (22) the

Perforation (7) at least partially covers.

5. Injection device (1) according to one of the preceding claims, wherein the component (5) is adapted to supply the fluid accelerated to the injector (2).

6. Injection device (1) according to one of the preceding claims, wherein the inlet opening (4) has a first cross-sectional area (8), and the first cross-sectional area (8) through the component (5) is filled to at least 40%.

7. Injection device (1) according to one of the preceding claims, wherein on the injector holder (3) an Eisdruckkompensationselement is provided which in addition is formed to receive an expansion of the fluid in the longitudinal direction (23).

Injection device (1) according to one of the preceding claims, wherein the injector (2) is clamped in the injector holder (3) with a spring (11).

A motor vehicle (12) comprising an internal combustion engine (13), an exhaust treatment device (15) for cleaning the exhaust gases of the internal combustion engine (13) and an injection device (1) according to any one of the preceding claims for supplying a fluid to the exhaust treatment device (15).