EP2668383A1

EP2668383A1 - Exhaust treatment device comprising an injector for supplying a fluid

Info

Publication number: EP2668383A1
Application number: EP12700829.0A
Authority: EP
Inventors: Klaus MÜLLER-HAAS
Original assignee: Emitec Gesellschaft fuer Emissionstechnologie mbH
Current assignee: Continental Automotive GmbH
Priority date: 2011-01-28
Filing date: 2012-01-20
Publication date: 2013-12-04
Also published as: JP2014505202A; DE102011009620A1; WO2012101041A1; US20130306156A1

Abstract

An apparatus includes an exhaust gas treatment device for purifying exhaust gases of an internal combustion engine. The exhaust gas treatment device includes at least one injector for supplying a fluid to the exhaust gas treatment device and at least one fan permitting ambient air to be actively delivered to the injector on demand, in order to cool the injector. A motor vehicle having the apparatus and a method for operating the motor vehicle are also provided.

Description

Exhaust treatment device with an injector

The invention relates to a device which has an exhaust gas treatment device for cleaning the exhaust gases of an internal combustion engine with at least one injector, which serves for supplying a fluid into the exhaust gas treatment device. Such a device is provided in particular in a ground-based motor vehicle.

Exhaust gas treatment devices, in which the exhaust gas is supplied with a fluid, are finding more and more widespread lately. Such exhaust gas treatment devices are, for example, exhaust gas purification devices in which inter alia the selective catalytic reduction method [SCR method; SCR = Selective Catalytic Reduction] is performed. In this method, a reducing agent is supplied to the exhaust gas, so that nitrogen oxide compounds in the exhaust gas can be effectively reduced. Ammonia is often used as the reducing agent. In particular, in automobiles ammonia is regularly not stored directly, but stored in the form of a reducing agent precursor, which is then converted into ammonia. This conversion (thermolysis and / or hydrolysis) often takes place in the exhaust gas. The reducing agent precursor can then be fed directly to the exhaust gas. A commonly used reductant precursor is urea-water solution. For example, a 32.5% urea-water solution as a reducing agent available under the trade name AdBlue ^®. When this reducing agent precursor is supplied to the exhaust gas, it is converted to ammonia due to the high temperature of the exhaust gas. The terms reducing agent and reducing agent precursor solution are used interchangeably below. Reducing agent precursor solution is also referred to as a reducing agent for simplicity.

For supplying the reducing agent into the exhaust gas treatment device, at least one injector is regularly used. This can, for example, at a portion of the exhaust pipe, in particular upstream be positioned in front of a so-called hydrolysis catalyst and / or a so-called SCR catalyst. These components are at least partially in the underbody of a motor vehicle. There are also known exhaust treatment devices to which a hydrocarbon-containing fluid (such as fuel) is supplied via an injector. The addition of (unburned) hydrocarbons is normally supplied to exhaust treatment devices to increase the temperature in the exhaust treatment device. When these hydrocarbons hit an oxidation catalyst, they burn with an exothermic reaction. By such a temperature increase, in particular, the conversion of pollutants in the exhaust gas can optionally be improved and / or soot deposits can be eliminated. The problem with the use of such injectors for supplying a fluid into an exhaust gas treatment device is regularly the positioning of the injector directly on the exhaust gas treatment device or at least close to the exhaust gas treatment device. There are regularly high temperatures and particularly strong temperature changes between a cold resting state and the operating temperature. This can lead to a) thermal overuse of the injectors, so that they are damaged and may no longer be able to meter the fluid exactly, and b) cause a change in the fluid properties and thus influence the operational safety.

On this basis, it is an object of the present invention to solve the problems described with reference to the prior art or to alleviate. In particular, a device is to be specified in which a thermal overload of the injector and a change of the supplied fluid is effectively avoided.

These objects are achieved with a device according to the features of claim 1. Further advantageous embodiments of the exhaust treatment device are given in the dependent formulated patent claims. The individually listed in the claims Features are in any, technologically meaningful, way combined with each other and can be supplemented by explanatory facts from the description, with further embodiments of the invention are shown.

The invention relates to a device comprising an exhaust gas treatment device for cleaning the exhaust gases of an internal combustion engine with at least one injector for supplying a fluid into the exhaust gas treatment device. In addition, at least one fan is provided with which ambient air to the injector can be conveyed for cooling the injector.

The exhaust treatment device is preferably an exhaust treatment device in which the selective catalytic reduction method can be performed. The fluid is then preferably a reducing agent for the SCR process. In addition, in a flow direction of the exhaust gases downstream of the injector in the exhaust treatment device, there is regularly provided an SCR catalyst having a catalytic coating to which nitrogen oxide compounds in the exhaust gas can be reacted together with the reducing agent. In addition, it is also possible to provide a hydrolysis catalyst between the SCR catalyst and the injector, by means of which a conversion of the reducing agent or of the reducing agent precursor takes place. The reducing agent precursor urea-water solution is reacted in the exhaust either thermally and / or assisted by a hydrolysis catalyst in ammonia. The ammonia reacts in the SCR catalyst together with the nitrogen oxide compounds in the exhaust gas to harmless substances such as nitrogen, water and carbon dioxide.

However, the invention is also applicable to an exhaust treatment device in which by means of an injector, a fuel, such as gasoline or diesel, is supplied. It is preferred that the at least one injector is attached to a portion of a flue-carrying line. In this case, the line can lead the entire exhaust gas flow or only a part of it (bypass). The line for the injector regularly has an opening and an injector seat on which the injector (exhaust gas-tight) is arranged so that z. B. whose nozzle section hineinerstreckt into inner regions of the conduit or at least adjacent thereto. In this respect, the injector is exposed to high temperatures by contact with the hot exhaust gas line and / or heat radiation and / or convection, in particular if it is positioned on the main exhaust gas line (possibly also near the internal combustion engine).

In principle, it is sometimes possible to cool such an injector by wind. For this purpose, guide plates can be provided on the vehicle, in particular in the area of the vehicle floor, which effect a (passive) cooling during driving operation. Here, however, it is (also) proposed to provide a controlled, active cooling, for example, if the vehicle does not move, such. As when refueling, at traffic lights, after switching off, etc. For this purpose, the device comprises at least one fan. In principle, it is possible that several blowers (eg two) are provided per injector and / or that one blower is assigned to several injectors. However, it is preferred that exactly one blower is assigned to one (each) injector. The blower may be provided in the immediate vicinity (eg attached to the motor vehicle) so that, for example, a direct supply of the ambient air is enabled, but it is also possible (alternatively or cumulatively) that a supply of one generated by the blower Ambient air flow takes place indirectly via baffles, guide tubes, etc. out. The fan is therefore preferably an active fan. In other words, this means that the blower has switched on and off as required, independently of the driving operation. For this purpose, the active fan may have its own (electromotive) drive, which is controlled by a controller. The blower can be, for example, a fan, a Roots blower or another device for activating ven promotion of ambient air. The fan preferably includes moving parts which serve to convey the ambient air. If necessary, these can be moved (passively) in contact with the driving wind in order to generate a supplementary (passive) ambient air flow towards the injector. In order for the injector to be cooled particularly well by the ambient air conveyed by the blower, the injector can have heat exchange surfaces which ensure an improved interaction of the ambient air with the injector for exchanging the temperature.

The device according to the invention is particularly preferred if the at least one fan has a drive means. The drive means may be, for example, an electric drive, in particular an electric motor. However, it is also possible that the drive means is a drive turbine driven by compressed air or exhaust gas, and / or that the drive means is formed by the internal combustion engine. If the drive means is formed by the internal combustion engine, then the blower is preferably connected via a shaft or a transmission, a V-belt or other movement and power transmission means with the drive shaft of the internal combustion engine.

Furthermore, according to the invention, when at least one flow-guiding device is provided on the at least one injector, the device can be conducted with the ambient air to the at least one injector. The flow directing device is preferably at least partially disposed between the blower and the injector so that the flow directing device redirects ambient air from the blower to the injector. The flow guiding device can also be designed, for example, as a flow deflection device. The flow-guiding device preferably comprises at least one of the following components: at least one guide plate, at least one tube section, at least one flow channel, at least one nozzle, at least one control flap. The flow-guiding device can also be arranged at least partially in the flow direction of the ambient air in front of the blower. So can the Strömungsleitvorrichtung ensure a particularly advantageous flow of the fan with. The at least one flow-guiding device can also be arranged such that, even in the event that the fan is not driven, it promotes ambient air (in particular wind) to the injector.

According to a development, a controller is provided, which is set up to activate and deactivate the at least one fan as needed. This control can also be integrated in a so-called engine control of a motor vehicle. Thus, the controller can evaluate in particular on the basis of (stored) maps, measured data or the like, whether currently a risk of thermal overload of the injector and / or a particularly accurate metering of the fluid is required and then turn on the fan at predetermined times and off again , In particular, the controller can also deactivate the fan again if sufficient cooling of the injector is again ensured without the fan. In particular, if a flow guide, which is, for example, by the wind of a motor vehicle, is in a position to ensure sufficient cooling of the injector, can be done by the control deactivation of the fan. As soon as sufficient cooling of the injector does not occur, the controller should be set up to identify these situations and reactivate the blower.

Also advantageous is the device when a temperature sensor is provided at the exhaust gas treatment device, with which the cooling or the temperature of the injector can be monitored. Such a temperature sensor is preferably arranged directly on the injector and / or a housing of the injector. Of course, it is also possible that such a temperature sensor is arranged with contact to the exhaust gas and / or the exhaust gas leading line, which can then be concluded from these measurement results on the temperature of the injector. In addition, such a temperature sensor is preferably connected to a controller which is set up to to deactivate or activate the blower. In this case, it is also preferable for the controller to take into account a current operating state of the internal combustion engine, such as, for example, the travel speed.

In the context of the invention, the device described above finds particular application in a motor vehicle having an internal combustion engine and an exhaust gas treatment device. The motor vehicle is preferably a passenger car or a heavy-duty vehicle for the road. In addition, the invention can also be used in mobile and stationary machines.

Such a motor vehicle is particularly advantageous when the motor vehicle has a control which is set up to deactivate the at least one fan when a speed of the motor vehicle rises above a limit speed and to activate when a speed of the motor vehicle is below the limit speed falls. In particular, when the motor vehicle is traveling at an increased speed, sufficient ambient air to the injector may already be conveyed through an intended flow-guiding device and the airstream of the motor vehicle without requiring an active operation of the fan. In order then to achieve a shutdown of the fan, a controller can be used in the motor vehicle. The controller may, for example, be (indirectly) connected to a speedometer in the motor vehicle in order to determine the travel speed of the motor vehicle.

Furthermore, a motor vehicle is preferred, wherein at least one fan for cooling the at least one injector also serves to cool the cooling water of the internal combustion engine. For example, the fan, which is provided on a cooling water heat exchanger in the front region of a motor vehicle, may also be designed to generate a cooling flow toward the injector. In addition, a method for operating a motor vehicle with a device comprising at least one injector is proposed, which comprises the following steps:

a) determining an injector reference temperature,

b) determining a driving condition of the motor vehicle,

c) activating an active cooling of the at least one injector, if at least one of the conditions i) and ii) are fulfilled:

i) the injector reference temperature is above an injector limit temperature,

ii) a driving condition "low load" or "high load" is present.

In the context of step a), the injector reference temperature may be a current (measured or calculated) value of the injector, the exhaust gas and / or the exhaust pipe. Step b) can also be measured and / or calculated on the basis of (stored) characteristic diagrams and / or sensors. For example, "high load," "normal load," "coasting," and "low load." "High load" then refers, for example, to high speed / high torque at low vehicle speed, "low load" to, for example, retirement and / or idle. In order to carry out the method, it is not necessary to repeat both steps a) and b) for each repetition; different temporal test intervals may be specified here. It is also possible that the order is reversed and / or that steps a) and b) occur simultaneously.

For example, a controller evaluates the results from steps a) and b) and determines an active cooling of the injector if the (current and / or future predicted) thermal load becomes too high. This can be done on the basis of a (stored) injector limit temperature (condition i)) and / or on the basis of a driving state "low load" or "high load", in which e.g. due to lack of driving wind (in the future) a thermal overload threatens.

The method can be implemented in particular with the devices or motor vehicles described here according to the invention. In this respect, all means and explanations that have been explained in connection with these devices or motor vehicles, equally apply here. The invention and the technical environment will be explained in more detail with reference to the figure. The figure shows a particularly preferred embodiment, to which the invention is not limited. In particular, it should be noted that the figure and in particular the illustrated proportions are only schematic. It shows:

Fig. 1 shows a motor vehicle, comprising an embodiment of an exhaust treatment device with injector and blower.

1 shows a motor vehicle 9, which has an internal combustion engine 2 and a device 17 with an exhaust gas treatment device 1 for cleaning the exhaust gases of the internal combustion engine 2. In the exhaust gas treatment apparatus 1, an injector 3 for supplying a fluid and an SCR catalyst 10 for performing the method of selective catalytic reduction in the exhaust gas treatment apparatus 1 are provided. The injector 3 is supplied via a line 16 from a tank 11 with fluid. The fluid is preferably a reducing agent for the SCR process or a reducing agent precursor (water-urea solution). At the exhaust treatment device 1, a blower 4 is provided, which promotes ambient air to the injector 3. The ambient air is indicated here as an arrow. In addition, a flow guiding device 6 can be provided on the exhaust gas treatment device 1, which diverts the ambient air to the injector 3. The fan 4 is preferably driven by a drive means 5. The drive means 5 can be controlled by a controller 7. The controller 7 can also process data from a temperature sensor 8, which is set up to monitor the temperature of the injector 3 and thereby determine to what extent cooling of the injector 3 is required. The controller 7 then controls the fan 4 with the aid of the temperature sensor 8. Various decoupling means 13 can also be provided on the injector 3, which can be used to transfer heat from the separator. Prevent or reduce gas treatment device 1 on the injector 3. As such decoupling means 13 shielding plates 14 are shown here by way of example, which reduce heat radiation from the exhaust gas treatment device 1 to the injector. Furthermore, bores 15 are provided here in the injector 3 or in a housing of the injector 3 as decoupling means 13, which reduce the thermally conductive cross section of the injector 3 or of a housing of the injector 3. Thus, the heat conduction through the injector 3 or through a housing of the injector towards the critical, functional components of the injector can be reduced. Such decoupling means 13 can effectively interact with the fan 4 and the flow guide 6 for cooling the injector 3.

The blower 4 and the flow-guiding device 6 are preferably arranged in the underfloor region 12 of the motor vehicle 9 and in working machines in the engine hood. This is especially true when the motor vehicle 9 is a passenger car or a truck. As a result, it can be ensured that the flow guiding device 6 is also able, when the fan 4 is not driven by the drive means 5, to redirect ambient air to the injector 3.

List of Reference Exhaust gas treatment device

Internal combustion engine

injector

fan

drive means

flow director

control

temperature sensor

motor vehicle

SCR catalyst

tank

Underbody area

decoupling means

shield

drilling

management

contraption

Claims

claims

Device (17), comprising an exhaust gas treatment device (1) for cleaning the exhaust gases of an internal combustion engine (2) with at least one injector (3) for supplying a fluid into the exhaust gas treatment device (1), wherein at least one fan (4) is provided, with which for cooling the injector (3) ambient air to the injector (3) can be promoted.

Device (17) according to claim 1, wherein the at least one fan (4) comprises a drive means (5).

Device (17) according to claim 1 or 2, wherein at least one injector (3) at least one Strömungsleitvorrichtung (6) is provided, with the ambient air to the at least one injector (3) can be passed.

Device (17) according to one of the preceding claims, wherein a controller (7) is provided which is adapted to activate and deactivate the at least one fan (4) as needed.

Device (17) according to one of the preceding claims, wherein a temperature sensor (8) is provided on the exhaust gas treatment device (1), with which the cooling of the injector (3) can be monitored.

Motor vehicle (9) comprising an internal combustion engine (2) and a device (17) according to one of the preceding claims.

Motor vehicle (9) according to claim 6, wherein the motor vehicle (9) has a controller (7) which is adapted to deactivate the at least one fan (4) when a speed of the motor vehicle (9) rises above a limit speed, and to activate when a speed of the motor vehicle (9) falls below the limit speed.

Motor vehicle (9) according to claim 6 or 7, wherein at least one fan (4) for cooling the at least one injector (3) also serves to cool the cooling water of the internal combustion engine (2).

Method for operating a motor vehicle (9) having a device (17) comprising at least one injector (3), comprising the following steps:

a) determining an injector reference temperature,

b) determining a driving state of the motor vehicle (9), c) activating an active cooling of the at least one injector (3) if at least one of the conditions i) and ii) are fulfilled: i) the injector reference temperature is above an injection gate limit temperature,

ii) a driving condition "low load" or "high load" is present.