• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    The invention relates to a device (1) for the selective catalytic reduction of nitrogen oxides in an exhaust tract (2) of a motor vehicle, comprising a tank (3) having a liquid which reduces nitrogen oxides or can be brought into such a form, in particular a urea solution (4 ), wherein the tank (3) can be filled up to a maximum level (5) with the liquid, a first line (6) with a conveying means (7) for conveying the liquid in the first line (6), a second line ( 8) connected to the first conduit (6) and returning to the tank (3) above the level (5), and a third conduit (9) connected to a connection point (10) of the second conduit (8). branches off at the first line (6) and via which the liquid in the exhaust gas duct (2) can be injected, wherein the first line (6) and the second line (8) are connected to each other optionally via a fourth line (11), the Pressure limiting means (12) au fweist, so that at an overpressure in the first line after the conveying means (7), the liquid for pressure relief in the second line (8) occurs. According to the invention, provision is made in the second line (8) for a switchable valve (13) and in the return flow direction (RS) upstream of a storage medium (14) for the liquid which expands against a force. This can be ensured at standstill of the motor vehicle, a rapid and substantially complete recycling of the liquid from a piping system in the tank (3).
    公开号:AT510671A1
    申请号:T1794/2010
    申请日:2010-10-29
    公开日:2012-05-15
    发明作者:Hanspeter Dipl Ing Mayer
    申请人:Hanspeter Dipl Ing Mayer；
    IPC主号:
    专利说明:

    * · · · · · · · · »**
    1
    Device for the selective catalytic reduction of
    Nitrogen oxides in an exhaust tract of a motor vehicle
    The invention relates to a device for the selective catalytic reduction of nitrogen oxides in an exhaust system of a motor vehicle, comprising a tank with a nitrogen oxides for reducing or bringable in such a form liquid, in particular a urea solution, wherein the tank up to a maximum level with the Liquid is fillable, a first conduit having a conveying means for conveying the liquid in the first conduit, a second conduit which is connected to the first conduit and leads back into the tank above the level, and a third conduit which at a connection point of the first line and the second line are optionally connected to each other via a fourth line having a pressure limiting means, so that at an overpressure in the first line after the conveying means the liquid to relieve pressure in the second line occurs.
    Nitrogen oxides, commonly referred to as NOx, are particularly dangerous components in the exhaust gases of motor vehicles, since nitrogen oxides, especially NO2, are toxic. In recent years, considerable efforts have been made to remove nitrogen oxides from exhaust gases from the engines of motor vehicles. In this regard, selective catalytic reduction has become widely accepted. For this purpose, a liquid, usually a urea solution, which is also known under the trade name AdBlue® used. The urea solution is injected into an exhaust tract of a motor vehicle, directly in front of a catalytic converter. On the catalyst, the urea solution decomposes to form ammonia. The ammonia reacts with the nitrogen oxides to form non-toxic nitrogen as well as water vapor.
    An apparatus for the selective catalytic reduction of nitrogen oxides in an exhaust tract of a motor vehicle comprises a tank in which a urea solution is usually stored, which is conveyed along a line to a metering valve with a conveying means, wherein the urea solution delivered to the metering valve is metered through the metering valve in the exhaust system. The commonly used urea solution has a freezing point of -11 ° C. In the operating state of the device, the urea solution is continuously or as a function of an exhaust gas composition ·· * · · · · t * tt tu 2 and / or temperature required for the metering valve and promoted by this in the exhaust system. However, as soon as the device comes to a standstill, in particular when the motor vehicle is turned off, urea solution inevitably remains in line sections of the device. This is particularly problematic when 5 an outside temperature drops to less than -11 ° C, since then the urea solution can freeze in the line sections. As a result, individual line sections may be clogged during a renewed startup of the motor vehicle and, in addition, the metering valve and the line system as a whole suffer damage, which can lead to a failure of the selective catalytic reduction. In order to avoid this, according to the state of the art devices are also known in which the entire line system is designed to be freeze-resistant. However, such solutions are particularly expensive.
    The object of the invention is to provide a device of the type mentioned, 15 in which a simple and quick as complete emptying of the conduit system is possible after operation or injection in a simple manner.
    This object is achieved according to the invention when, in a device of the type mentioned in the second line, a switchable valve and upstream in the return flow direction 20 are provided with a storage medium for the liquid which expands against a force.
    An advantage achieved by the invention is to be seen in particular in the fact that the individual lines, in particular a line section between conveyor and metering pump 25 and a recirculating line in the tank section, can be quickly and at least almost completely emptied and vented. Thus, a risk of freezing a liquid, in particular a urea solution, is significantly reduced in the individual line sections. In the storage medium which expands against a force, the liquid is stored during operation or injection 30, wherein a pressure is applied as at the metering valve. As soon as the conveyor is stopped and operation is interrupted, the switchable valve opens and the pressure in the storage medium can be relieved by moving the fluid towards the tank. By this pulse, a continuous liquid column is formed, so that it leads to a substantially complete emptying of the individual 3
    Line sections between conveyor and metering pump or conveyor and switchable valve comes. A line section between the conveyor and the tank is not emptied, but this can be counteracted either by the conveyor is arranged on the bottom side of the tank or briefly operated in the reverse direction, at most even in the remaining pipe sections existing residues of the liquid in be pumped back the tank.
    In a device according to the invention, it is also advantageous that this also allows a substantially complete emptying of individual pipe sections in an exclusively mechanical manner. For this purpose, the switchable valve can be designed so that it opens automatically quickly in case of a drop in electrical voltage or a power failure and thus the desired emptying of the line sections is given. It is possible, for example, that the switchable valve is spring-loaded and when a sudden drop in operating voltage, the spring force is released to switch the valve in an open state. This is particularly useful in an emergency. In such emergency shutdown or "shut-down" function can be ensured by the storage medium in conjunction with the switchable valve extensive emptying of line sections, even if no operating voltage is given. As a result of the emptying, freezing of the solution at low temperatures in the line sections is prevented.
    The conveying means may be designed in any desired manner, but is advantageously a delivery pump, in particular a diaphragm pump. If a diaphragm pump is provided, it may be driven by an electric motor or a vibrating magnet. In order to possibly also allow a return conveyance of residual liquid remaining in the tank after emptying of lines, the feed pump is preferably designed so that it can promote the liquid in the conveying direction and after emptying the lines against the conveying direction during operation or injection,
    Conveniently, the conveyor is preceded by a filter in a conveying direction, so that contamination of individual line sections can be avoided. 4
    When emptying the line sections or a relaxation of the storage medium and the formation of a continuous liquid column forms at the end of a suppression. To counteract this suppression, the first conduit may communicate with a vent valve. Through this vent valve can enter from the outside air from the outside in the first line to ventilate them or to reduce or avoid a negative pressure. In this regard, it is expedient that the fourth line is provided and the ventilation valve is arranged between a connection point of the fourth line and the connection point of the second line. It is particularly preferred that the vent valve automatically opens in the first line in the section after the conveyor, viewed in the conveying direction at a suppression. An automatic opening is expediently ensured by a purely mechanical ventilation valve, so that it can be activated automatically in the already mentioned emergency. For example, it can be provided that the ventilation valve is a non-return valve mounted against a spring force. Such a check valve opens automatically when air pressure is applied to an outside, but in the first line, a smaller pressure than the air pressure is given.
    In a region of the first conduit, a pressure sensor may be provided to control a pressure and to control the delivery means in response to this pressure.
    The storage medium can be designed, for example, as a piston mounted against a spring force. Other variants are conceivable. It is also possible, for example, that at least a portion of the second conduit is formed as a pressure-elastic line section, which inflates at a given pressure and contracts again when opening the switchable valve to an original cross-section.
    In accordance with the above-described advantages of a device according to the invention, it is preferably used in a motor vehicle with an exhaust gas tract.
    Further features, advantages and effects of the invention will become apparent from the embodiment illustrated below. In the drawing, to which reference is made, the only Fig. 1 shows a device according to the invention.
    5
    In Fig. 1, an inventive device 1 is shown, which is coupled to an exhaust tract 2 of an engine of a motor vehicle. The device 1 comprises a tank 3 in which a urea solution 4 or another liquid which reduces nitrogen oxides or can be brought into such a form by reaction or decomposition is stored up to a level 5. At a bottom of the tank 3, a first line 6 connects, which extends to a connection point 10 of a second line 8. Along the first line 6, a conveyor 7 is provided, usually a diaphragm pump, which can backfördem the urea solution 4 both in the conveying direction FR and opposite thereto or in the tank 3. Furthermore, a pressure sensor 18, which, like the conveying means 7, is connected to a central control unit 20, is provided on the first line 6. The signals of the pressure sensor 18 are fed to the control unit 20, which controls the conveyor 7 in response to these signals. The conveyor 7 is preceded by a filter 15 in the conveying direction FR to filter out any suspended matter or the like from the urea solution 4 and thus have a purified solution for later injection solution available. The first line 6 is as mentioned at the connection point 10 in the second line 8 via. Moreover, a third line 9, which has a metering valve 21, branches off at the connection point 10. About the metering valve 21, a predetermined amount of urea solution 4 is introduced into the exhaust tract 2. For this purpose, an atomizer opening into the exhaust tract 2 is expediently provided, which discharges the urea solution 4 in a finely distributed manner. However, it can also be provided that an outlet of the metering valve 21 opens directly into the exhaust tract 2. In the exhaust tract 2, the injected urea solution 4 decomposes on a catalyst, not shown, with the formation of ammonia, which in turn reacts with nitrogen oxides of the exhaust gas. In order to inject optimal amounts of the urea solution 4 into the exhaust tract 2, a temperature sensor 19 is provided in the exhaust tract 2, which, like the pressure sensor 18 and the conveying means 7, is in communication with the central control unit 20. The second line 8 opens above the level 5 in the tank 3 and can, as shown in Fig. 1, be additionally connected to the first line 6 via a fourth line 11. In the fourth line 11, a pressure limiting means 12 is provided, which may be a spring-loaded check valve. The pressure limiting means 12 releases the fourth line 11 when a pressure in the first line 6 reaches a predetermined threshold. After release of the fourth line 11, the urea solution 4 can then be recycled via the fourth line 11 and the second line 8 6 in the tank 3 until the predetermined threshold is fallen below again and the pressure limiting means 12 closes the fourth line 11 again
    In the area of the second line 8, a storage medium 14 is provided in the section between the connection point 10 and 5 to a connection point of the fourth line 11, which as illustrated comprises a piston displaceable against a spring force. Alternatively, it is also possible, for example, that the storage medium 14 is designed as a pressure-elastic line section of the second line 8. In the return flow RS the storage medium 14 is a switchable valve 13 downstream. The switchable valve 13 10 communicates with the central control unit 20 and can be switched to an open state if necessary, in the region of the first line 6, a vent valve 16 is provided after a connection point 17 of the fourth line 11, usually a spring-loaded check valve , During operation of the device, the conveying means 7 promotes urea solution 4 to the metering valve 21. Via the metering valve 21, a required quantity of the urea solution 4 is supplied to the atomiser in the exhaust tract 2. In this case, with regard to the conveying means 7, a quantity-controlled metering pump or a constant-flow feed pump can be provided. Too much subsidized urea solution 4 generates an overpressure and is returned via the fourth line 11 in the tank 3. Furthermore, in operation, depending on the given pressure, the storage medium 14 20 is expanded against a force.
    In the case of emergency ventilation in the event of unforeseen parking of a vehicle or failure of the electrical voltage as well as in the case of regular venting after dosing, the valve 13 is opened quickly and the present in the storage medium 14 25 pressure reduced. The stored pressure relieves in the form of a liquid column in the direction of the second line 8 to the tank 3 and generates a delivery pulse. This delivery impulse is so strong that the upstream lines to the conveyor 7 are completely or at least largely emptied. Due to the resulting negative pressure by the pulse, the vent valve 16 opens and air flows into the individual 30 line sections. At the same time, the conveyor 7 a possibly in the
    Line sections still residual small amount of urea solution 4 pump back into the tank. It is also possible to have an emergency shut-off function, for which the switchable valve 13 is designed such that it mechanically opens when there is a drop in electrical voltage, thus initiating the above-described process of emptying individual pipe sections and ventilating the same. With sufficient electrical voltage then closes the switchable valve 13 again. During emptying and venting, it is advantageous that the metering valve 21 is closed, so that no exhaust gases and in the case of diesel-powered vehicles soot particles can get into the individual line sections.
    权利要求:
    Claims (10)
    [1]


    8. Device (1) for the selective catalytic reduction of nitrogen oxides in an exhaust tract (2) of a motor vehicle, comprising a tank (3) with a nitrogen oxide reducing or can be brought into such a liquid form, in particular a urea solution (4 ), wherein the tank (3) can be filled up to a maximum level (5) with the liquid, a first line (6) with a conveying means (7) for conveying the liquid in the first line (6), a second line ( 8) connected to the first conduit (6) and returning to the tank (3) above the level (5), and a third conduit (9) connected to a connection point (10) of the second conduit (8). branches off at the first line (6) and via which the liquid in the exhaust gas duct (2) can be injected, wherein the first line (6) and the second line (8) are connected to each other optionally via a fourth line (11), the Pressure limiting means (12) aufwei st, so that at an overpressure in the first line (6) after the conveying means (7) the liquid for pressure relief in the second line (8) enters, characterized in that in the second line (8) a switchable valve (13) and upstream of the return flow direction (RS), there is provided a storage medium (14) for the liquid which expands against a force.
    [2]
    2. Device (1) according to claim 1, characterized in that the conveying means (7) is designed as a feed pump, in particular a diaphragm pump.
    [3]
    3. Device (1) according to claim 1 or 2, characterized in that the conveying means (7) in a conveying direction (FR), a filter (15) is connected upstream.
    [4]
    4. Device (1) according to one of claims 1 to 3, characterized in that the first line (6) with a vent valve (16) is in communication.
    [5]
    5. Device (1) according to claim 4, characterized in that the fourth line (11) is provided and the ventilation valve (16) between a connection point (17) of the fourth line (11) and the connection point (10) of the second line ( 8) is arranged.

    9
    [6]
    6. Device (1) according to claim 4 or 5, characterized in that the vent valve (16) at a suppression in the first line (6) in the section after the conveying means (7), in the conveying direction (FR) considered automatically opens.
    [7]
    7. Device (1) according to one of claims 1 to 6, characterized in that in a region of the first line (6), a pressure sensor (18) is provided.
    [8]
    8. Device (1) according to one of claims 1 to 7, characterized in that the storage medium (14) is designed as a bearing against a spring force piston. 10
    [9]
    9. Device (1) according to one of claims 1 to 7, characterized in that at least one section of the second line (8) is designed as a pressure-elastic line section.
    [10]
    10. Motor vehicle with an exhaust gas tract (2), comprising a device (1) according to one of claims 1 to 9.
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    同族专利:
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    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    DE19947197A1|1999-10-01|2001-04-12|Bosch Gmbh Robert|Device and method for dosing a reducing agent|
    DE10127834A1|2001-06-08|2002-12-12|Bosch Gmbh Robert|Device for dosing a reducing agent, especially urea or a urea-water solution, comprises units for introducing the agent into a catalyst arrangement, a dosing valve arranged at the end|
    WO2006074833A1|2005-01-17|2006-07-20|Robert Bosch Gmbh|Exhaust gas subsequent processing method and method therefor|
    DE19819579C1|1998-04-30|1999-09-30|Siemens Ag|Secondary treatment of exhaust from lean burn diesel engine with SCR catalyst, minimizing pump usage and energy consumption|
    DE19946900A1|1999-06-22|2000-12-28|Bosch Gmbh Robert|Complex system dosing and mixing urea and air, used for nitrogen oxide conversion in vehicle exhaust purification systems, is integrated into or onto single plastic or metal block|
    JP2008151094A|2006-12-20|2008-07-03|Aisan Ind Co Ltd|Exhaust emission control device for internal combustion engine|
    DE102008009650A1|2008-02-18|2009-08-27|Robert Bosch Gmbh|Dosing device for dosing e.g. urea water solution into exhaust gas in diesel engine of motor vehicle, has turn-off device equipped to partly empty dosing module and/or supply system by energy during loss of power supply of dosing device|
    DE102008036265A1|2008-08-04|2010-02-11|J. Eberspächer GmbH & Co. KG|Emission control device for commercial motor vehicle, has container provided with overflow for agent, where overflow is closed by changing device during unactuation of changing device and is opened during actuation of changing device|DE102012008788A1|2012-05-07|2013-11-07|Albonair Gmbh|Reducing agent metering system with automatic ventilation of the reducing agent line|
    DE102012211875A1|2012-07-06|2014-01-09|Robert Bosch Gmbh|Delivery module for an operating / auxiliary substance for the aftertreatment of exhaust gas|
    JP5995665B2|2012-11-09|2016-09-21|ボッシュ株式会社|Reducing agent supply device|
    FR2998615A1|2012-11-28|2014-05-30|Inergy Automotive Systems Res|SCR SYSTEM AND METHOD FOR ITS PURGING|
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    法律状态:
    2016-06-15| MM01| Lapse because of not paying annual fees|Effective date: 20151029 |
    优先权:
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    EP11187058A| EP2447490A1|2010-10-29|2011-10-28|Device for selective catalytic reduction of nitrogen oxides in an exhaust gas line of a motor vehicle|
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