Injection device for adding a liquid additive

Abstract

Injection device (1) for adding a liquid additive (2) to an exhaust gas treatment device (3), wherein the injection device (1) has an outlet region (4) that can be contacted with the exhaust gas treatment device (3), a connection region (5) spaced from the outlet region (4) and having a fluid line connection (6), and a channel (28) for the additive (2) that runs from the connection region (5) to the outlet region (4), and the injection device (1) has a valve (7) for controlling the addition of the additive and at least one heat flow adjusting means (25) that specifies a freezing direction (10) in the channel (28) from the outlet region (4) to the connection region (5), wherein the connection region (5) is surrounded by a heat flow adjusting means (25) designed as a cover (12), wherein an air cushion (13) is formed between the cover (12) and the valve (7).

Description

[0001] The invention relates to an injection device for adding a liquid additive to an exhaust gas treatment device.

[0002] Exhaust gas treatment devices to which an additive is added are known from the prior art. Such exhaust gas treatment devices employ special exhaust gas purification processes in which the exhaust gas of a connected internal combustion engine is purified with the aid of the additive. For example, certain pollutant components in the exhaust gas can be converted into harmless substances using the additive, and / or the addition of the additive can influence the ambient conditions in the exhaust gas treatment device in a way that is beneficial for the conversion. Water, fuel, oxidizing agents, and / or reducing agents can be used as (liquid) additives, for example.

[0003] An increasingly used exhaust gas purification process in exhaust gas treatment systems is the selective catalytic reduction (SCR) process. In this process, a reducing agent is added to the exhaust gas to convert nitrogen oxide compounds in the exhaust gas into harmless substances, namely nitrogen, water, and CO2. Ammonia is the preferred reducing agent. Ammonia is not normally stored in motor vehicles but in the form of a reducing agent precursor solution, which can be converted into the actual reducing agent when needed. An aqueous urea solution, for example, can be used as a reducing agent precursor solution. A suitable 32.5% aqueous urea solution is available under the trade name AdBlue. ®The reducing agent can be converted into the reducing agent (ammonia) either externally in the exhaust gas in a dedicated converter and / or internally in the exhaust gas treatment device. The conversion can be carried out purely thermally by heating the reducing agent precursor solution. Furthermore, catalytic support of the conversion reaction by a catalyst is possible, in particular a so-called hydrolysis catalyst. The terms "reducing agent" and "reducing agent precursor solution" are used synonymously below.

[0004] For the addition of liquid additive to an exhaust gas treatment device, a controlled and / or independently (pressure-dependent) operating injection device (comprising a nozzle, an injector, a valve, or the like) is particularly suitable. Due to the typically high temperatures of the exhaust gases in an exhaust gas treatment device, the injection device should be designed to be correspondingly resistant to high temperatures. A valve is often arranged in the injection device, which can be opened and closed in a controlled manner to supply the liquid additive. Such a valve is usually particularly temperature-sensitive and should therefore be protected from the high temperatures of the exhaust gas treatment device. In particular, it should be ensured that the dosing accuracy is not negatively affected, even with these temperature fluctuations.

[0005] Another problem is that aqueous additives (especially reducing agents) can freeze at low ambient temperatures. The described 32.5% urea-water solution "Ad-Blue ® For example, it freezes at just -11°C. Such low temperatures can occur in a vehicle, for example, during long periods of inactivity. When freezing, the additive expands. This can damage the injection system if it still contains additive when it freezes.

[0006] To protect an injection device from the expansion of the reducing agent in the event of freezing, various solutions are known from the prior art. European patent EP 1 747 394 B1, for example, shows an injection valve designed to open when the reducing agent in the valve freezes. Any resulting volume expansion can then escape into the exhaust gas treatment device. However, this results in uncontrolled addition to the exhaust system, which, in addition to unfavorable reaction conditions, also results in increased consumption.

[0007] From German patent application DE 10 2009 032 487 A1, it is also known to provide an additional lateral valve on an injection device, which is connected to a return line to the reducing agent tank. Any volume expansion that occurs in the event of freezing can then be dissipated back into the tank through this valve. However, this version is technically relatively complex and potentially prone to failure because the return line actually has to branch off inside the injection device to achieve emptying there.

[0008] DE 10 2008 022 991 A1 discloses a device for conveying a reducing agent, in particular a liquid urea-water solution, comprising at least two elements from the group consisting of storage means (e.g., tank), conveying means (e.g., pump), deflection means (e.g., valve), detection means (e.g., sensor), separation means (e.g., filter), and outlet means (e.g., nozzle, injector), which are connected to one another by a conduit, wherein at least one element is pressure-sensitive and the adjacent conduit near this pressure-sensitive element forms at least one heat sink. This provides a device with a targeted freezing behavior, so that pressure-sensitive elements are protected.

[0009] DE 10 2009 029 409 A1 discloses a method for operating an electromagnetically controllable metering valve arranged in an exhaust system of an internal combustion engine. For metering reducing agent in the exhaust system, the metering valve is controlled by a control and / or regulating device via an electromechanical drive unit with a first current profile that has a holding current phase with a first holding current level when the metering valve is open. The metering valve and the drive unit are part of a metering module. When the internal combustion engine is shut down, the metering valve is controlled via the drive unit with a second current profile that has a second holding current level that is higher than the first holding current level. An independent claim is directed to a control unit configured to implement the method.

[0010] DE 10 2007 026 892 A1 discloses a device for the metered injection of a liquid exhaust gas aftertreatment agent, preferably an aqueous urea solution, into an exhaust system of an internal combustion engine, comprising at least one device body having a working chamber and at least one volume compensation element that adjusts the working chamber volume according to a volume change of the liquid exhaust gas aftertreatment agent during its phase transition. It is provided that the material of the volume compensation element has a temperature-dependent expansion coefficient such that the volume change is responded to with a volume change caused by the volume compensation element.

[0011] Based on the above prior art, the object of the present invention is to provide an injection device for injecting a liquid additive into an exhaust gas treatment device, which at least partially solves the technical problems mentioned above. In particular, the novel injection device should not be damaged by freezing of the additive. Furthermore, the injection device should be particularly simple in terms of technology and control, and should be cost-effective. Furthermore, advantageous methods for freezing an injection device for an additive and methods for manufacturing such an injection device should be provided.

[0012] These objects are achieved with an injection device according to the features of patent claim 1, as well as with a method for freezing an injection device according to the features of patent claim 9, and with a method for producing an injection device according to the features of patent claim 11. Further advantageous embodiments of the invention are specified in the respective dependent claims. The features listed individually in the patent claims can be combined with one another in any technologically expedient manner and can be supplemented by explanatory facts from the description, whereby further embodiments of the invention are demonstrated.

[0013] The invention relates to an injection device for adding a liquid additive to an exhaust gas treatment device, wherein the injection device has an outlet region that can be contacted with the exhaust gas treatment device, a connection region spaced from the outlet region with a fluid line connection and a channel for the additive that runs from the connection region to the outlet region, and the injection device has a valve for controlling the addition of the additive and at least one heat flow adjusting means that specifies a freezing direction in the channel from the outlet region to the connection region, wherein the connection region is surrounded by a heat flow adjusting means designed as a covering hood, wherein an air cushion is formed between the covering hood and the valve.

[0014] The air cushion (or space containing air) thus also exists between the channel running through the injection device and the cover. A heat flow control device, consisting of a cover and an air cushion, acts like thermal insulation arranged around the connection area of ​​the injection device. Of course, several (separate) air cushions can also be used.

[0015] The two aforementioned heat flow adjusting means can be assigned to the second group mentioned above. Preferred examples of heat flow adjusting means from the first group are explained in particular below. These heat flow adjusting means can, of course, be used in any combination with one another.

[0016] An injection device refers, in particular, to a component that can be contacted, for example, with a designated opening in the wall of an exhaust gas treatment device or exhaust line. The injection device can thus be permanently or detachably mounted, attached, and / or flanged to the exhaust gas aftertreatment device, preferably in a gas-tight manner. The injection device consists, for example, of an injector and an injector holder, as well as possibly other elements. For example, a cap can be provided that closes the injector holder and thereby covers the injector. The injector is, for example, an injection valve, similar to those used for adding fuel to an internal combustion engine.

[0017] The “outlet region” and the “connection region” each refer to (self-explanatory) regions of the injection device. If the injection device is viewed as a three-dimensional component, the outlet region is in particular the region which, when installed, is arranged in the vicinity of an exhaust gas treatment device, and the connection region is preferably the region where a line for the additive can be connected to the injection device. Typically, a parting plane can be assumed between the outlet region and the connection region through the injection device. Normally, the outlet region and the connection region are arranged opposite one another. The fact that the connection region is spaced from the outlet region means in particular that there is a distance between the connection region and the outlet region.Typically, the injector is elongated and the outlet area is located on one side or end and the connection area is located on the opposite side or end of the injector.

[0018] The channel is preferably formed inside the injection device and connects the connection area to the outlet area. The additive flows through the channel from the fluid line connection into the exhaust treatment device. The channel partially passes through the connection area and partially through the outlet area. The channel can be filled with additive. For this purpose, the channel has an internal volume. The channel does not have to run in a straight line, but can have deflections, bends, or the like. The channel also does not have to have a uniform cross-section over its entire length from the connection area to the outlet area. Cross-sectional differences along the channel are possible, particularly in the area of ​​the valve.

[0019] The valve is preferably designed to close the channel at predetermined times (in a controlled and / or complete manner). When the channel is closed with the valve, no more additive is passed through the channel of the exhaust gas treatment device. The valve can be used to control the amount of additive supplied. The valve can, for example, have a movable valve armature which closes the channel when closed and opens the channel when open. The valve armature can, for example, be moved electromagnetically. The valve has, for example, an electromagnetic coil which can exert a force on the movable valve armature when an electric current flows through the coil.

[0020] The freezing device preferably runs completely along the channel. If the channel has at least one bend or turn, the freezing direction preferably follows these deflections. However, it is also possible for the freezing direction not to completely or exactly follow every bend or turn in the channel, but rather to be defined by an (imaginary) straight line connecting the outlet area and the connection area. In any case, this is understood in particular to mean that the freezing direction essentially results from the course of the channel from the outlet area to the connection area or from the direction of the channel.

[0021] Heat flow adjustment devices on the injection device can be divided into two different groups. The first group of heat flow adjustment devices are heat conduction structures, which promote internal heat flow through the heat conduction structure. Heat flow is therefore preferentially directed along a heat conduction structure. The second group are thermal insulation devices, which impede internal heat flow through the thermal insulation. Heat flow is therefore redirected by thermal insulation.

[0022] By appropriately selecting the heat flow adjustment means on the injection device with regard to their placement and effect on a heat flow, a preferred, directed heat flow in the injection device can be specified in the event of freezing. The freezing direction of the injection device is usually oriented opposite to the preferred flow direction of the heat flow. This alignment of the freezing direction and the flow direction of the heat flow arises automatically because the heat flow initially removes heat from where the heat can dissipate most quickly, and therefore frozen additive forms there first. In the injection device proposed here, a plug of frozen reducing agent therefore initially forms in the outlet region. This plug then grows or enlarges in the injection device towards the connection area.

[0023] The at least one heat flow adjusting agent is therefore selected and positioned such that, at a sustained ambient temperature below the freezing point of the additive, the additive in the channel initially freezes at the outlet area, and then this ice formation spreads toward the connection area. The resulting increase in volume of the freezing additive in the channel is thus compensated for by pushing the still liquid portions of the additive toward or beyond the connection area. This prevents potentially harmful ice pressure, while simultaneously achieving a technically simple return of the additive to the reducing agent system.

[0024] The injection device is particularly advantageous if the connection area is surrounded by a heat flow adjustment means designed as thermal insulation, which is designed as a plastic sheath molded onto the injection device.

[0025] If thermal insulation is provided at the connection area, in the event of freezing or cooling of the injection device, a heat flow from the injection device through the connection area into the environment surrounding the injection device is reduced. A heat flow out of the injection device through the outlet area is then stronger or greater than the described heat flow beyond the connection area. Preferably, the thermal insulation is designed such that the amount of thermal energy stored in the injection device is almost completely dissipated through the outlet area into a connected exhaust gas treatment device and / or no significant heat flow is dissipated through the connection area into the environment of the injection device. Preferably, the injection device is completely encased in plastic.The molded-on plastic casing can be constructed with additional material that is applied in certain areas to the continuous plastic casing of the injection device. The continuous plastic casing of the injection device can also be constructed in certain areas, particularly in the vicinity of the connection area, with a greater wall thickness than in the outlet area. This also allows the heat flow out of the injection device in the connection area to be (further or more strongly) limited, while simultaneously promoting the heat flow out of the injection device through the outlet area, thus creating a freezing direction from the outlet area to the connection area.

[0026] It is considered advantageous that the outlet region has at least one heat flow adjustment means designed as a heat conducting structure for discharging heat from the injection device into a contactable exhaust gas treatment device.

[0027] Such a heat-conducting structure promotes the flow of heat through the outlet region out of the injection device. A heat-conducting structure can, for example, be embodied as a metallic insert in the injection device, particularly if the injection device (externally) is made predominantly of plastic. A metallic insert as a heat-conducting structure can be injected and / or cast into the plastic. A metallic insert in an injection device made of plastic causes heat to flow away through the metallic insert, thus significantly determining the heat flow through the injection device. The heat-conducting structure can be in direct heat-conducting contact with the exhaust gas treatment device. The exhaust gas treatment device typically has a metal wall (exhaust pipe). In a particularly preferred embodiment, the heat-conducting structure is directly connected to the wall of the exhaust gas treatment device.This can be done, for example, with a screw. The heat-conducting structure can thus also serve to attach the injection device to the exhaust treatment device. Particularly preferred is close contact with the channel in the exhaust area; for example, the channel there is also at least partially formed or delimited by the heat-conducting structure.

[0028] The heat conduction structure is preferably designed such that, when shut down or frozen, it acts as a heat conduction structure to conduct heat from the injection device to the exhaust gas treatment device, but during normal operation it does not conduct heat from the exhaust gas treatment device into the injection device, or only conducts it to a lesser extent. This can be achieved, for example, by the heat conduction structure being designed with at least one bi-metal. A bi-metal deforms under the influence of temperature. The heat conduction structure designed with a bi-metal can be configured such that, at high temperatures of the exhaust gas treatment device, it interrupts thermal contact between the exhaust gas treatment device and the injection device (for example mechanically), and at low temperatures (in the event of freezing), thermal contact is established between the injection device and the exhaust gas treatment device.

[0029] The injection device is also advantageous if the injection device has a valve holder in which the valve is arranged and which is designed to contact the injection device on the exhaust gas treatment device, wherein at least one coolant channel for a coolant is formed in the valve holder, through which coolant can flow during operation of the injection device in order to cool the valve, wherein the coolant channel acts like a heat flow adjustment means designed as a heat conducting structure during an operational break of the injection device.

[0030] When an injection device is in operation during operation of the exhaust gas treatment device, it is advantageous that the temperature in the injection device does not rise to such an extent that the injection device (and in particular the valve arranged in the injection device) is damaged. For this purpose, the injection device can be designed with a coolant channel through which a coolant flows. The coolant channel can be connected to a cooling circuit of an internal combustion engine. The coolant of the internal combustion engine is then also used as the coolant for the injection device. A liquid coolant allows a very large amount of heat to be dissipated from the injection device to the environment, even with small temperature differences. During operation, the temperature of the injection device is then preferably not significantly higher than the temperature of the coolant.

[0031] During the period in which the additive freezes in an injection device, the injection device and its cooling circuit are typically out of operation. However, the coolant located there can still be liquid because the coolant preferably contains substances that significantly lower the freezing point of the coolant, so that the coolant remains liquid even at very low temperatures. Preferably, the coolant is still liquid at temperatures below -20°C, and more preferably the coolant only freezes at temperatures below -35°C. When the injection device is deactivated, the coolant in the coolant channel in the injection device is therefore liquid. However, it is not kept in motion in the cooling circuit. Due to temperature differences in the coolant, a flow in the coolant in the coolant channel can still occur or be induced.This flow can be used to ensure that the coolant channel forms a particularly effective heat conduction medium or a particularly effective heat conduction structure in the injection device. The cooling channel is preferably designed such that, in the event of freezing, it conducts heat from the injection device through the outlet region to an exhaust gas treatment device via a coolant flow in the coolant channel. Very particularly preferably, there is close contact with the channel in the region of the outlet region; for example, the channel is also at least partially formed or delimited there by the wall of the cooling channel.

[0032] Furthermore, it is particularly advantageous if at least one heat flow adjusting means designed as a heat conducting plate is arranged in the coolant channel.

[0033] A heat-conducting plate arranged in the coolant channel can itself already have a heat-conducting function. It is also possible for such a heat-conducting plate to serve (only) to promote the flow of coolant in one direction through the outlet region out of the injection device. A heat-conducting plate in the coolant channel can, in particular, ensure that a (locally) circulating flow of reducing agent is established in the coolant channel, which transports heat from the injection device to the outlet region in a first flow direction and forms a return flow in an opposite second flow direction, so that the coolant flows back once it has released the heat in the outlet region. Such a heat-conducting plate preferably divides the coolant channel into two (at least partially) parallel channels.

[0034] According to a further development, it is also proposed that at least one ice pressure compensation element is provided at the connection area, with which an increase in volume of the additive during solidification can be compensated.

[0035] An ice pressure compensation element is preferably designed such that, in the event of freezing, it releases additional volume into which the volume increase of the additive during solidification can escape. For this purpose, a connection region can have a wall section adjacent to the additive, which is (in particular reversibly) movable. By means of an evasive movement, this wall section can increase the volume filled with additive in the channel. As already explained, during freezing, an ice plug of frozen additive preferably initially forms in the outlet region of the injection device. This ice formation continuously spreads in the freezing direction, so that the liquid additive is pushed from the outlet side towards the connection side.In order to fully compensate for the increase in additive volume (inside the injection device) with as little technical effort as possible, it is advantageous to position the ice pressure compensation element where liquid additive is still present until the very end. Since the freezing direction in the injection device described here runs from the outlet side to the connection side, the ice pressure compensation element should be located on the connection side. The ice pressure compensation element is also particularly well protected on the connection side from heat generated by the exhaust treatment device during operation.

[0036] The injection device is particularly advantageous if the ice pressure compensation element is designed as a displaceable fluid line connection which is prestressed such that the fluid line connection does not shift at a regular operating pressure.

[0037] A movable fluid line connection can be designed, for example, as a plug that is attached to an injector or a valve in the injection device using a movable O-ring. Even if the fluid line connection is moved relative to the injector, the connection between the fluid line connection and the injector remains fluid-tight thanks to the O-ring. Preloading of the fluid line connection can be achieved, for example, by holding the fluid line connection in an operating position with a tensioned spring. As soon as a force triggered by the increase in volume of the additive becomes greater than the force exerted by the spring, the fluid line connection moves from the operating position to an ice-compensation position.

[0038] Within the scope of the invention, a method for freezing an injection device for adding a liquid additive to an exhaust gas treatment device is further proposed, which method has the following structure. The injection device has an outlet region that is in contact with the exhaust gas treatment device, a connection region with a fluid line connection that is spaced from the outlet region, and a channel extending from the connection region to the outlet region. The method comprises at least the following steps: a) generating a heat flow from the injection device through the outlet region into the exhaust gas treatment device with at least one heat flow adjusting means which surrounds the connection region and is designed as a cover, so that an air cushion is formed between the cover and the valve; b) at least partially preventing a flow of heat from the injection device through the connection area into an environment of the injection device in the connection area; c) specifying a freezing direction in the channel from the outlet area towards the connection area; d) forming a plug of frozen reducing agent in the channel at the outlet region; and e) Enlarging the plug in the direction of freezing.

[0039] The described method is applied in an injection device whenever the temperatures surrounding the injection device have dropped so low that the additive begins to freeze or solidify. To generate a heat flow in step a), heat-conducting structures and / or thermal insulation can be used as heat flow adjusting means in the manner described.

[0040] Thermal insulation causes heat flow wherever there is little or no thermal insulation. Heat flow is particularly directed through designated heat-conducting structures.

[0041] The prevention of heat flow in step b) can also be achieved by heat flow adjustment means in the manner described. Heat-conducting structures prevent heat flow in directions other than the direction of the heat-conducting structure. Thermal insulation prevents heat flow through the insulation. Heat flow is directed, in particular, around designated thermal insulation.

[0042] The heat flow adjustment means determine a freezing direction for step c) in the channel from the outlet area to the connection area. The freezing direction does not have to be oriented exactly along the channel. The freezing direction can also roughly follow the direction of the channel from the outlet area to the connection area.

[0043] In step d), the channel in the injection device is first blocked or sealed at the outlet area by a plug so that no more reducing agent can leave the injection device and reach the exhaust line. Preferably, the channel in the outlet area is designed so that the plug firmly engages the channel and cannot be dislodged or displaced by enlarging the plug. This can be achieved, for example, by a rough and / or undercut channel wall in the outlet area and / or by a component provided with a perforated structure (interrupted surface structure).

[0044] In step e), the plug is enlarged in the freezing direction (further toward the connection area of ​​the injection device) until the additive present in the injection device is completely frozen. The increase in volume of the total additive in the injection device can then be compensated for in a subsequent step f) with an ice pressure compensation element, which limits the pressure in the channel or in the injection device.

[0045] The described method makes it possible to freeze the reducing agent present in an injection device without causing damage to the injection device.

[0046] The method is particularly advantageous if, for step a), a coolant channel is used as heat influence adjusting means, via which a heat flow flows out of the injection device through the outlet region into the exhaust gas treatment device.

[0047] For this purpose, a preferably (locally) circulating coolant flow forms in the coolant channel, which transports heat through the outlet area. Cooled coolant flows from the injection device toward the outlet area, and reheated coolant flows from the outlet area into the injection device. The term "locally circulating" here specifically means that the coolant does not circulate within the entire cooling circuit of a motor vehicle, but only locally, within the injection device.

[0048] Within the scope of the invention, a method for producing an injection device for adding a liquid additive to an exhaust gas treatment device is also proposed. The injection device has at least one outlet region that can be contacted with an exhaust gas treatment device, a connection region with a fluid line connection spaced from the outlet region, and a channel extending from the connection region to the outlet region. The method comprises at least the following steps: i) connecting the injection device to an exhaust gas treatment device; ii) filling the channel with additive; (iii) lowering the temperature in an area surrounding the injection device; iv) determining a freezing direction of the additive in the channel; and v) integrating at least one heat flow adjusting means on the injection device so that a freezing direction from the outlet region to the connection region is achieved, wherein the heat flow adjusting means surrounds the connection region and is designed as a cover hood so that an air cushion is formed between the cover hood and the valve.

[0049] The method according to the invention for producing an injection device can in particular also be used as a test method to provide suitable heat flow adjustment means on an injection device and / or to check whether the injection device has a predetermined freezing direction (steps i) to iv)).

[0050] In a first variant of the method for producing an injection device, the method steps i) to v) can be carried out once for a specific type of injection device, and then the heat flow adjustment means can be designed accordingly for all injection devices of this type in series production.

[0051] In a second variant of the method for manufacturing an injection device, process steps i) to v) can be performed once for each new application of an injection device. Subsequently, the heat flow adjustment means can be configured accordingly for all injection devices of a specific type used in this application. An application here refers to a specific use of the injection device in a specific motor vehicle or in a specific type of motor vehicle. This procedure is particularly preferable when the exhaust gas treatment device has a significant and / or even decisive influence on the freezing direction.

[0052] For process step iii), it is advantageous if the temperature in the vicinity of the injection device is reduced to the extent that it later occurs during regular use of the injection device (real operating conditions). For example, for step iii), the components provided in the vicinity of the injection device are precisely those that are actually provided in its vicinity during regular operation of the injection device. Such components normally influence the heat distribution in the vicinity of the injection device when the temperature is reduced. It is therefore advantageous to take these components and their influence on the temperature distribution in the vicinity of the injection device into account for the process for manufacturing an injection device.A freezing direction in an injection device in step iii) can be determined, for example, by carrying out the process with several injection devices in parallel and terminating the process at different times in each case when the additive has not yet completely frozen in the freezing direction. The individual injection devices with which the process was carried out can then be examined to determine where and / or to what extent the reducing agent has frozen. This can be checked, for example, using an ultrasound method and / or an X-ray method. It is also possible to disassemble the injection devices with which the process was carried out in order to determine where frozen reducing agent was present and where it was not.

[0053] Within the scope of the invention, a motor vehicle is also specified, comprising an internal combustion engine and an exhaust gas treatment device for cleaning the exhaust gases of the internal combustion engine, wherein an injection device according to the invention for injecting an additive is provided on the exhaust gas treatment device.

[0054] The particular advantages and design features described for the injection device are applicable and transferable to the two described methods. The same applies to the particular advantages and design features described for the two methods (the manufacturing method and the freezing method). These advantages and particular design features are transferable to the injection device according to the invention. Thus, the manufacturing method is particularly suitable for producing the injection device described according to the invention.

[0055] The invention and the technical environment are explained in more detail below with reference to the figures. The figures show particularly preferred embodiments, to which the invention is not limited, however. It should be noted that the figures, and in particular the proportions shown, are only schematic. They show: Figure Ref. 1: a first embodiment of an injection device; Figure Ref. 2: a second embodiment of an injection device; Figure Ref. 3: a third embodiment of an injection device; Figure Ref. 4: a heat-conducting insert for an injection device with a coolant channel; Figure Ref. 5: another heat-conducting insert for an injection device with a coolant channel; and Figure Ref. 6: a motor vehicle comprising an injection device according to the invention.

[0056] The different design variants of an injection device shown in Figure Ref. 1, Figure Ref. 2 and Figure Ref. 3 have some common features, which are initially explained together below.

[0057] The injection device 1 has a connection region 5 with a fluid line connection 6 and an outlet region 4. The outlet region 4 is contacted by an exhaust gas treatment device 3. The connection region 5 is spaced from the exhaust gas treatment device 3. The exhaust gas treatment device 3 is designed, for example, in the manner of an exhaust line. Exhaust gas can flow through it during operation, which is indicated here by an arrow. The injection device 1 has a valve holder 14 and a valve 7 arranged in the valve holder 14. The valve 7 can, for example, be an injection valve or an injector, such as is also used, for example, to determine the amount of fuel for an internal combustion engine. The valve holder 14 serves to mount the valve 7 and usually also establishes a mechanical connection to the exhaust gas treatment device 3.A channel 28, which is filled with additive 2, extends through the injection device 1 from the connection area 5 to the outlet area 4.

[0058] All embodiments of the injection device 1 according to Figure Ref. 1, Figure Ref. 2 and Figure Ref. 3 each have heat flow adjusting means 25 which predetermine a freezing direction 10 in the injection device 1 so that the freezing direction is oriented in the channel 28 from the outlet region 4 towards the connection region 5. In each case, a plug 27 of frozen additive 2 is shown in the outlet region 4. In the event of freezing, the heat flow adjusting means 25 result in a heat flow 26 counter to the freezing direction 10 from the injection device 1 beyond the outlet region 4. In the embodiments according to Figure Ref. 1 to Figure Ref. 3, heat conducting structures 8 and heat insulation 9 are provided as heat flow adjusting means 25.

[0059] In the embodiment according to Figure Ref. 1, a cover 12 is provided on the injection device 1 as thermal insulation 9, by means of which an air cushion 13 is created between the valve 7 or the channel 28 and the environment around the injection device 1, which insulates the injection device 1 or the valve 7 or the channel 28 in the connection area 5 from the environment of the injection device 1. Furthermore, in the embodiment according to Figure Ref. 1, an ice pressure compensation element 17 is provided in the connection area 5, by means of which an increase in volume in the valve 7 or in the channel 28 that occurs during freezing can be compensated.

[0060] In the embodiment according to Figure Ref. 2, the thermal insulation 9 is designed as a plastic sheath 11, which can, for example, be molded onto a component of the injection device 1. An ice pressure compensation element 17 is also provided in the embodiment according to Figure Ref. 2. The ice pressure compensation element 17 is designed here in that the fluid line connection 6 is preloaded against the valve 7 by a spring 22 and a holder 23. The fluid line connection 6 can perform a compensating movement against the spring force of the spring 22 to compensate for an increase in volume during freezing.

[0061] In the embodiment according to Figure Ref. 3, a cover 12 is also provided as thermal insulation 9, forming an air cushion 13. A channel 28 serves as the heat conduction structure 8, in which additional heat conduction inserts 20 with heat conduction plates 16 are arranged.

[0062] The design variant according to Figure Ref. 3 also has an ice pressure compensation element 17 in the connection area 5.

[0063] Figure Ref. 4 and Figure Ref. 5 show heat-conducting inserts 20. These heat-conducting inserts 20 are special components, each having a plurality of heat-conducting sheets 16. The heat-conducting inserts 20 can be inserted into the coolant channel 15 according to Figure Ref. 3. Figure Ref. 4 shows the lower heat-conducting insert 20 shown in Figure Ref. 3. Figure Ref. 5 shows the upper heat-conducting insert 20 shown in Figure Ref. 3. The heat-conducting inserts each consist of the heat-conducting sheets 16 and at least one carrier ring 21, which specifies the position of the heat-conducting sheets 16 relative to one another. Using such heat-conducting inserts 20, a plurality of heat-conducting sheets 16 can be inserted into the coolant channel 15 together in one work step. The heat-conducting inserts 20 shown in Figure Ref.The heat-conducting insert 20 shown in Figure 4 is designed such that the heat-conducting plates 16 are aligned in the coolant channel 15 such that the heat-conducting plates 16 are positioned directly in the outlet region against a valve for metering the fluid into the exhaust gas treatment device, and heat is thus transported directly to the outlet region 4. The heat-conducting plates 16 of the heat-conducting insert 20 according to Figure Ref. 4 bend for this purpose when installed. The heat-conducting plates 16 are preferably aligned such that they impede the regular cooling flow of the coolant through the coolant channel 15 as little as possible during operation of the injection device.

[0064] Figure 5 shows a motor vehicle 18 having an internal combustion engine 19 and an exhaust gas treatment device 3 for purifying the exhaust gases of the internal combustion engine 19. An additive can be supplied to the exhaust gas treatment device 3 via an injection device 1. The injection device 1 is supplied with additive by an additive supply device 24.

[0065] Even if the design variants shown in the figures here have similarities, this does not necessarily mean that these must always be present. Likewise, it is not necessary that the different design features can be used (only) alternatively. Rather, a person skilled in the art can easily make technically reasonable modifications from these variants, taking the general description into account.

[0066] Based on the above prior art, the invention provides an injection device for injecting a liquid additive into an exhaust gas treatment device, which at least partially solves the technical problems mentioned above. In particular, damage to the injection device due to freezing of the additive is avoided. Furthermore, the injection device is particularly simple in terms of technology and control and can be manufactured cost-effectively. Furthermore, advantageous methods for freezing an injection device for an additive and methods for manufacturing such an injection device are provided. List of reference symbols 1 injection device 2 Additive 3 Exhaust gas treatment device 4 Outlet area 5 Connection area 6 Fluid line connection 7 Valve 8 Thermal conduction structure 9 Thermal insulation 10 Freezing direction 11 Plastic coating 12 Cover 13 air cushions 14 valve holders 15 Coolant channel 16 Heat conducting plate 17 Ice pressure compensation element 18 Motor vehicle 19 Internal combustion engine 20 thermal inlay 21 Carrier ring 22 spring 23 Bracket 24 Additive supply device 25 Heat flow adjusting agents 26 Heat flow 27 plugs 28 channel

Claims

[1] Injection device (1) for adding a liquid additive (2) to an exhaust gas treatment device (3), wherein the injection device (1) has an outlet region (4) that can be contacted with the exhaust gas treatment device (3), a connection region (5) spaced from the outlet region (4) with a fluid line connection (6), and a channel (28) for the additive (2) that runs from the connection region (5) to the outlet region (4), and the injection device (1) has a valve (7) for controlling the addition of the additive and at least one heat flow adjusting means (25) that specifies a freezing direction (10) in the channel (28) from the outlet region (4) to the connection region (5), wherein the connection region (5) is surrounded by a heat flow adjusting means (25) designed as a cover (12), wherein an air cushion (13) is formed between the cover (12) and the valve (7). is trained. [2] Injection device (1) according to claim 1, wherein the connection region (5) is surrounded by a heat flow adjusting means (25) designed as thermal insulation (9), which is designed as a plastic sheath (11) injection-molded onto the injection device (1). [3] Injection device (1) according to one of the preceding claims, wherein the outlet region (4) has at least one heat flow adjusting means (25) designed as a heat conducting structure (8) for discharging heat from the injection device (1) into a contactable exhaust gas treatment device (3). [4] Injection device (1) according to one of the preceding claims, which has a valve holder (14) in which the valve (7) is arranged and which is designed to contact the injection device (1) on the exhaust gas treatment device (3), wherein in the valve holder (14) at least one coolant channel (15) for a coolant is formed, through which coolant can flow during operation of the injection device (1) in order to cool the valve (7), wherein the coolant channel (15) acts like a heat flow adjusting means (25) designed as a heat conducting structure (8) during an operational break of the injection device (1). [5] Injection device (1) according to claim 4, wherein at least one heat flow adjusting means (25) designed as a heat conducting plate (16) is arranged in the coolant channel (15). [6] Injection device (1) according to one of the preceding claims, wherein at least one ice pressure compensation element (17) is provided on the connection region (5), with which an increase in volume of the additive (2) during solidification can be compensated. [7] Injection device (1) according to claim 6, wherein the ice pressure compensation element (17) is designed as a displaceable fluid line connection (6) which is prestressed such that the fluid line connection (6) does not shift at a regular operating pressure. [8] Method for freezing an injection device (1) for adding a liquid additive (2) to an exhaust gas treatment device (3) with an outlet region (4) which is in contact with the exhaust gas treatment device (3), a connection region (5) with a fluid line connection (6) which is spaced from the outlet region (4), and a channel (28) extending from the connection region (5) to the outlet region (4), comprising at least the following steps: a) generating a heat flow (26) from the injection device (1) through the outlet region (4) into the exhaust gas treatment device (3) with at least one heat flow adjusting means (25) which surrounds the connection region (5) and is designed as a cover (12), so that an air cushion (13) is formed between the cover (12) and the valve (7); b) at least partially preventing a heat flow (26) from the injection device (1) through the connection region (5) into an environment of the injection device (1) in the connection region (5); c) specifying a freezing direction (10) in the channel (28) from the outlet region (4) towards the connection region (5); d) forming a plug (27) of frozen reducing agent in the channel at the outlet region (4); and e) Enlarging the plug (27) in the freezing direction (10). [9] Method according to claim 8, wherein for step a) a coolant channel (15) is used as heat influence adjusting means (25), via which a heat flow (26) flows out of the injection device (1) through the outlet region (4) into the exhaust gas treatment device (3). [10] Method for producing an injection device (1) for adding a liquid additive (2) to an exhaust gas treatment device (3) with an outlet region (4) which can be contacted with an exhaust gas treatment device (3), a connection region (5) with a fluid line connection (6) which is spaced from the outlet region (4), and a channel (28) extending from the connection region (5) to the outlet region (4), comprising the following steps: i) connecting the injection device (1) to an exhaust gas treatment device (3); ii) filling the channel (28) with additive (2); iii) lowering the temperature in an environment of the injection device (1); iv) determining a freezing direction (10) of the additive (2) in the channel (28); and v) integrating at least one heat flow adjusting means (25) on the injection device (1) so that a freezing direction (10) from the outlet region (4) to the connection region (5) is achieved, wherein the heat flow adjusting means (25) surrounds the connection region (5) and is designed as a cover (12) so that an air cushion (13) is formed between the cover (12) and the valve (7). [11] Motor vehicle (18) comprising an internal combustion engine (19) and an exhaust gas treatment device (3) for cleaning the exhaust gases of the internal combustion engine (19), wherein an injection device (1) according to one of claims 1 to 7 for injecting an additive (2) is provided on the exhaust gas treatment device (3).

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