DE102008009650A1 - 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 - Google Patents

Abstract

The device (110) has a dosing module (116) for dosing a pollutant-decreasing medium (112). A supply system (114) provides the pollutant-decreasing medium to the dosing module. A turn-off device (126) has energy storage (134) and plunger spring storage (128) partially loaded with energy during an operation of the dosing device. The turn-off device is equipped to partly empty the dosing module and/or the supply system by the energy stored in the energy storage and plunger spring storage during loss of the power supply of the dosing device.

Description

State of the art

The The invention is based on known methods and devices for Aftertreatment of exhaust gases, in particular exhaust gases of internal combustion engines, For example, in the automotive sector, in energy production or in similar fields of science and technology.

From such areas techniques are known, in which polluting media, in particular fluid media (for example, liquids or gases) metered into the exhaust gas, for example, sprayed become. In this case, different techniques and different types of media are used, which, for example, in DE 10 2004 004 738 A1 are described.

However, an essential application example, to which the present invention is not limited, is the spraying of a urea-water solution into the exhaust gas of diesel engines in order to reduce the proportion of nitrogen oxides (NOx) in the exhaust gas. In this case, the NO x is reduced to N ₂ O in a reduction reaction to form nitrogen and water. Other reducing agents and / or reducing agent precursors (which, for example, only convert to the reducing agent in the exhaust gas or in the region of the exhaust gas) are also known. Such methods are often also referred to as SCR (Selective Catalytic Reduction) methods. By selective catalytic reduction, for example, nitrogen oxides are reduced to high selectivity to nitrogen, whereby the nitrogen oxide concentration in the exhaust gas can be significantly reduced. Urea-water solutions as examples of reducing agents are available, for example, under the brand name "AdBlue." Thermal decomposition of the urea results in the urea as the reducing agent precursor, the actual reducing agent, namely gaseous ammonia.

Besides methods and devices based on the use of reducing agents or reducing agent precursors as pollution reducing media, other types of pollution reducing media are also known. For example, in DE 10 2004 004 738 A1 , which describes post-engine heating of exhaust gas by injecting fuel into the exhaust line, thereby achieving the exhaust gas temperatures required to regenerate downstream catalytic converters or diesel particulate filters. Thus, this is an example of an "indirect" pollutant reducing medium, but its introduction into the exhaust also serves generally the purpose of short-term, medium-term or long-term pollutant reduction Many other embodiments of pollutant-reducing media are known.

A major challenge with known pollutants Systems and dosing devices is to design these frost-resistant. In particular, as shown above, in many cases aqueous systems used as pollutant-reducing media, for example, the named AdBlue. Especially with these systems However, it must be ensured that these systems are frost-proof be configured and no frost damage by freezing suffer. For this purpose are in many from the state of the art known systems, the components of the system in the Abstellfall either blown out by compressed air or the pollutant reducing medium for example, sucked back by a pump.

These However, solutions prepare in the event of a failure the metering device and / or a metering device comprising Systems problems, since in this case a proper Shutdown is not guaranteed in many cases can be. Such disorders can in particular with a failure of the power supply of the metering device and / or be connected to a system comprising the metering device. Also deliberately induced disturbances, for example user induced interference and / or automatically (for example via a controller) induced disturbances, For example, in the context of an emergency stop function, can cause such problems.

In in the case of a breakdown of the power supply or in a Voltage drop due to other electrical defects can be as described above Draining not done properly or be completed, so that system components, if necessary at low temperatures, for example temperatures below -11 ° C for AdBlue, be damaged by freezing can. In that sense, in many cases, nothing else remains as the individual components of the metering device and / or one of the Dosing device comprehensive system itself to make ice pressure resistant. However, this ice-resistant design is often technical only inadequately feasible and with increased System costs associated.

Disclosure of the invention

The invention is based on the recognition that known systems, which in the Abstellfall either blow out the metering device by compressed air or suck by means of a pump, after switching off still secondary energy in the form of compressed air and / or electricity need to blow out or To ensure that they are sucked back and thus produce frost protection. A basic idea of the present invention is to use energy for this function, which is stored during operation of the system in an energy storage, so that in the Abstellfall the required function of emptying or otherwise frost protection can be perceived without further external supplies.

It is therefore a metering device for dosing a pollutant Medium proposed in an exhaust gas, which in particular according to the Dosing devices described above can be configured and which in particular for introducing a reducing agent and / or of a reducing agent precursor into the exhaust gas can be. In particular, the metering device as part of a pollutant reducing system in an internal combustion engine, in particular in a motor vehicle, are used.

The Dosing device comprises a dosing module for dosing the pollutant reducing Medium, for example, comprise one or more metering valves can, for example, the pollution-reducing medium in the Inject or spray exhaust gas. Furthermore includes the metering device is a supply system for providing the pollutant reducing medium to the metering module. This supply system For example, it may include one or more storage tanks, for example Liquid tanks for AdBlue intake. Furthermore, that can Supply system include one or more supply lines, which connected to the metering module. The supply system can continue one or more pumps and / or other types of conveyors comprise a flow of the pollutant reducing medium through to ensure the supply system, in particular one Flow from a storage tank through the supply line to the Dosing.

to Implementation of the idea described above comprises the metering device furthermore at least one switch-off device with at least one energy store. The energy store or the shutdown device are set up, to the energy storage during operation of the metering device at least partially charged with energy. The shutdown device is further set to in case of malfunction of the metering device and / or a system comprising the metering device, in particular in case of failure of the power supply of the metering device, the Dosing module and / or the supply system by means of the energy storage at least partially empty energy stored. This emptying can in particular be done automatically, d. H. without an additional external activation of the shutdown device is required.

Especially the shutdown device can at least one directly or indirectly by the power supply controlled switch and / or a direct or indirectly by the power supply of the metering device and / or a system comprising the metering device Have valve. This switch or the valve can be set up to interfere with the dosing device and / or the system comprising the metering device automatically to change a switching position and in the energy storage stored energy at least partially release, so that the Emptying described above can take place. This switch and / or This valve may in particular comprise a 4/2-way valve, wherein but also other embodiments, in particular embodiments of valves, are possible.

The Emptying can be particularly the supply system, d. H. especially a supply line of the supply system, and / or the dosing module itself, in particular a metering valve of the dosing, all or partially affect. The emptying can in particular by applying the dosing module and / or the supply system with an overpressure and / or carried out with a negative pressure. In particular, the supply system comprise a supply line connected to the metering module, wherein the shutdown device at a junction with the Supply line is connected. For example, the shutdown device comprise a branch line from the supply line, which branches off at the junction of the supply line.

The Supply line then preferably comprises one of the connection point side facing a shut-off, in particular a at a Disturbance of the metering device and / or one of these metering device comprehensive system automatically blocking shut-off. In this way it is guaranteed that in the mentioned Incident by means of the turn-off preferably only the section of the supply line between the connection point and the metering module and / or the metering module itself be emptied, whereas the remaining part of the supply system, which by the Shutoff is separated from the shutdown device, almost can remain unchanged. The shut-off can, for example a check valve and / or a solenoid valve, in particular a normally closed solenoid valve, and / or a pump, which in the off state preferably completely locks, include. However, other types of shut-off are possible.

Further advantageous embodiments of the metering relate to the Energy storage. Thus, the energy storage in particular at least one the following energy storage include: a mechanical energy storage, in particular an energy store with an elastic element and / or a spring element, in particular a helical spring element; a piston accumulator; a hydraulic energy store; a diaphragm accumulator. The said energy storage can also be combined, so that, for example a hydraulic energy storage, for example in the form of a Piston spring accumulator, with a mechanical energy storage in Shape, for example, a spring element can be combined. The mentioned energy storage characterized by a possible simple and inexpensive Design and high reliability and durability.

The The shutdown device can in particular during operation of the metering device pressurizable by means of the pollutant reducing medium Include pressure tank, which communicates with the energy store, d. H. an active compound stands. In this further development of Invention can use the pollution-reducing medium itself be used as an energy carrier to the energy storage charge. The shutdown device can then be set up in particular be in order to disturb a dosing device and / or a system comprising the metering device, in particular at a failure of the power supply, which is located in the pressure tank Pollutant-reducing medium with at least partial release drain the energy of the energy storage from the pressure tank. This Discharging can be done in particular in a storage tank, for example via a compensation line connecting the pressure tank and the storage tank.

alternative or in addition to the pressure tank, the shutdown device one in connection with the energy storage, d. H. in active connection standing vacuum tank. The active compound can in particular be configured conversely to operative connection of the pressure tank, so that, for example, a relaxation or discharge of the energy storage a reduction in volume of the pressure tank while increasing the volume of the Low pressure tanks causes and vice versa. Are two tanks provided, So a vacuum tank and a pressure tank, it is in particular possible, as below with reference to an embodiment is explained in more detail, if this means, for example a valve (for example, a 4/2-way valve) alternately either via the branch line with the supply line are connectable or via the compensation line with the Storage tank, so that each exactly one of the chambers with the storage tank and one is connected to the supply line.

The Deployment device can be set up in particular in such a way that this in case of malfunction of the metering device and / or a system comprising the metering device, d. H. for example at a particular type of disorder, especially one Failure of the power supply of the metering device, at least partial release of stored in the energy storage Energy the supply system and / or the dosing module at least partially emptied. In this emptying is the pollutant Medium from the supply system and / or the dosing module at least partially sucked into the vacuum tank. In particular, this can be be done by the vacuum tank via a branch line connectable to the supply line, this connection for example, by means of an opening at a fault Valve can be done. For example, this valve can be as above indicated, in the event of a fault such that a pressure tank is connected to the storage tank, for example via the equalization line. The branch line can in particular a cross-section reducing element include, for example, a throttle element. For example, the throttle element can ensure that while a charging process of the energy storage in regular operation the dosing device is not deprived of too much power. The Throttle element can be used as a throttle element with a fixed cross-section and / or also designed as an adjustable and / or adjustable throttle element be.

Brief description of the drawings

embodiments The invention is illustrated in the drawings and in the following Description explained in more detail.

It demonstrate

1 an embodiment of a metering device according to the invention in a schematic representation; and

2 a section of the metering device according to 1 with a shut off position of the 4/2-way valve of the shutdown device.

embodiments the invention

In 1 is an embodiment of a metering device according to the invention 110 for dosing a pollutant reducing medium 112 shown schematically. The dosing device 110 includes a supply system 114 to the pollutant-reducing medium 112 , which may be, for example, AdBlue, to a dosing module 116 provide. The supply system 114 includes for this purpose a storage tank 118 and a storage tank 118 and the Dosiermo dul 116 connecting supply line 120 , The dosing module 116 For example, it may comprise a pressure- and / or actuator-controlled metering valve, as known from the prior art. To promote the pollutant reducing medium 112 is in the supply line in this embodiment 120 a pump 122 taken up, with a pump motor 124 ,

In addition to the supply system 114 comprises the metering device according to the invention 110 to implement the above-described inventive concept, a shutdown device 126 , The shutdown device 126 in turn comprises a piston spring accumulator 128 , with a storage enclosure 130 , a piston 132 and a mechanical energy storage 134 , which is designed in the present embodiment as a helical spring. The piston spring accumulator 128 and the mechanical energy storage 134 are only two possible embodiments of usable in the context of the present invention energy storage.

The piston 132 divides the interior of the storage enclosure 130 in a pressure tank 136 and a vacuum tank 138 , The piston 132 is sliding in the storage enclosure 130 stored and separates the pressure tank 136 and the vacuum tank 138 tight, allowing an overflow of pollutant reducing medium 112 directly from the pressure tank 136 in the vacuum tank 138 or vice versa is not possible. A piston rod 140 is slidable through the storage enclosure 130 in the area of the vacuum tank 138 guided, wherein the guide is designed pressure-tight, so that along the piston rod 140 no pollutant-reducing medium from the vacuum tank 138 can escape. The pressure tank 136 is with a first connection line 142 can be filled or emptied, and the vacuum tank 136 by means of a second connecting line 144 ,

Furthermore, the shutdown device 126 one at a junction 146 from the supply line 120 branching branch line 148 on. In this branch line 148 is a throttle element 150 taken, which may be preferably configured with a variable throttle cross-section.

Furthermore, the shutdown device 126 a compensation line 152 on, which in this embodiment, without pressure in the storage tank 118 empties. Between the branch line 148 and the compensation line 152 as first line pair and the first connection line 142 and the second connection line 144 the second line pair is a 4/2-way valve 154 switched, which in each case one of the two lines 148 . 152 with one of the two lines 142 . 144 connects and the other of the wires 148 . 152 with the other one of the lines 142 . 144 , Here is the 4/2-way valve 154 arranged such that in an energized, ie energized state, the branch line 148 with the first connection line 142 connected, and the compensation line 152 with the second connection line 144 , In 2 is, however, another switching state of the 4/2-way valve 154 shown, with only a section of the defeat 126 is shown. The state shown there is the de-energized state in which the branch line 148 with the second connection line 144 connected, and the compensation line 152 with the first connection line 142 ,

The piston spring accumulator 128 with the mechanical energy storage 134 is during operation of the metering device 110 or one the metering device 110 comprehensive system with pollution-reducing medium 112 preloaded and thereby loaded. The pump 122 builds up pressure for this purpose and promotes the pollutant-reducing medium 112 from the storage tank 118 to the dosing module 116 , At the junction 146 is via the branch line 148 and the throttle element 150 as an optional component and the powered 4/2 way valve 154 pollutant reducing medium 112 in the pressure tank 136 of the piston spring accumulator 128 promoted. This will cause the piston 132 in 1 pressed down, the spring of the energy storage 134 is compressed, and the piston spring accumulator 128 and the mechanical energy storage 134 to be charged. At the same time, this is the volume of the vacuum tank 138 reduced. A pressure equalization takes place by the fact that pollution-reducing medium 112 from the vacuum tank 138 over the second connection line 144 , the 4/2-way valve 154 and the compensation line 152 in the storage tank 118 is encouraged.

An idea of the present invention is the energy of the piston spring accumulator 128 or the mechanical energy storage 134 during the operation of the metering device 110 energized and thus charged with energy to use in case of failure to be part of the supply system 114 , in particular the supply line 120 between the junction 146 and the dosing module 116 and / or the Do siermodul 116 slowly or completely slowly sucking empty. The control is in this case via solenoid valves, in particular the 4/2-way valve 154 , wherein this solenoid valve preferably switches on voltage or energy waste.

In Abstellfall the metering device 110 , For example, in the engine shutdown and / or in the event of power failure occurs in 1 presented system as follows in action. The pump 122 stops and blocks the connection within the supply line 120 to the supply tank 118 , The pump 122 thus acts as a shut-off element itself 156 , Optionally, however, for this blocking function also, alternatively or additionally, another shut-off 156 be provided, for example, a normally closed solenoid valve.

Further falls the 4/2-way valve 154 off and off of the in 1 position shown in the in 2 shown position. This is the pressure tank 136 of the piston spring accumulator 128 depressurized and receives a connection to the storage tank 118 over the equalization line 152 , The energy storage 134 , in particular the spring of this energy storage 134 , pushes the piston 132 in the direction of the pressure tank 136 and empties the pressure tank 136 over the equalization line 152 in the storage tank 118 ,

In the vacuum tank 138 This builds up a negative pressure, which via the second connection line 144 , the branch line 148 and the throttle element 150 also in the section of the supply line 120 between the shut-off element 156 and the dosing module 116 is applied. This will make this section and the dosing module 116 even at least partially sucked empty and for example by a seat leakage of the dosing 116 or a metering valve of this metering module 116 self-ventilated or partially emptied.

In the in the 1 and 2 illustrated embodiment, the energy storage 134 in the context of a piston spring accumulator 128 realized. Generally, the energy storage 134 itself preferably in addition to a spring accumulator include a piston or diaphragm accumulator. In addition, the piston spring accumulator 128 , in particular the vacuum tank 138 be configured with a compensation volume or a compensating device, so that this is the extension of the extracted pollutant reducing medium 112 can compensate for freezing. Such a compensation device may comprise, for example, a movable membrane and / or a gas bubble.

The entire system, especially the dosing device 110 themselves, can also be protected against frost during vehicle operation. This can be realized in particular by targeted heating and / or by waste heat of ancillaries. For example, waste heat of the cooling water, exhaust gases or the like can be used to the metering device 110 itself at least largely protect against freezing. Additional heating devices may also be provided, for example electric heaters, which the metering device 110 according to 1 or heat components thereof wholly or partially during operation. The piston spring accumulator 128 In addition, through its massive design or other features from damage by the freezing and thereby expanding pollutant reducing medium 112 to be protected.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• DE 102004004738 A1 [0002, 0004]

Claims (13)

Dosing device ( 110 ) for dosing a pollutant reducing medium ( 112 ) into an exhaust gas, in particular for introducing a reducing agent and / or a reducing agent precursor into the exhaust gas, comprising a dosing module ( 116 ) for dosing the pollutant reducing medium ( 112 ), further comprising a supply system ( 114 ) for providing the pollutant-reducing medium ( 112 ) to the dosing module ( 116 ), further comprising a shutdown device ( 126 ), wherein the shutdown device ( 126 ) an energy store ( 128 . 134 ), wherein the energy store ( 128 . 134 ) during operation of the dosing device ( 110 ) is at least partially charged with energy, wherein the shutdown device ( 126 ) is set up in the event of a malfunction of the metering device ( 110 ) and / or a metering device ( 110 ), in particular in the event of a loss of power to the dosing device ( 110 ), the dosing module ( 116 ) and / or the supply system ( 114 ) by means of in the energy store ( 128 . 134 ) stored energy stored at least partially. Dosing device ( 110 ) according to the preceding claim, wherein the shutdown device ( 126 ) is set up to perform the emptying automatically. Dosing device ( 110 ) according to the preceding claim, wherein the shutdown device ( 126 ) a switch and / or a valve ( 154 ), in particular a switch controlled directly or indirectly by the power supply and / or a valve controlled directly or indirectly by the power supply ( 154 ), wherein the switch and / or the valve ( 154 ) are set up in order to prevent a malfunction of the metering device ( 110 ) and / or a metering device ( 110 ), in particular in the event of a loss of power to the dosing device ( 110 ), to automatically change a switching position and in the energy storage ( 128 . 134 ) at least partially release stored energy. Dosing device ( 110 ) according to the preceding claim, wherein the switch and / or the valve ( 154 ) a 4/2-way valve ( 154 ). Dosing device ( 110 ) according to one of the preceding claims, wherein the supply system ( 114 ) one with the dosing module ( 116 ) connected supply line ( 120 ), wherein the shutdown device ( 126 ) at a connection point ( 146 ) with the supply line ( 120 ), the supply line ( 120 ) from the junction ( 146 ) facing away from the supply line ( 120 ) a shut-off element ( 156 ), in particular in case of a malfunction of the metering device ( 110 ) and / or a metering device ( 110 ) comprehensive system automatically blocking shut-off element ( 156 ). Dosing device ( 110 ) according to the preceding claim, wherein the shut-off element ( 156 ) comprises at least one of the following elements: a check valve; a solenoid valve, in particular a normally closed solenoid valve; a pump ( 122 ). Dosing device ( 110 ) according to one of the preceding claims, wherein the energy store ( 128 . 134 ) at least one of the following energy stores ( 128 . 134 ) comprises: a mechanical energy store ( 134 ), in particular an energy store with an elastic element and / or a spring element, in particular a helical spring element; a piston accumulator, in particular a piston spring accumulator ( 128 ); a hydraulic energy store ( 128 ); a diaphragm accumulator. Dosing device ( 110 ) according to one of the preceding claims, wherein the shutdown device ( 126 ) during operation of the metering device ( 110 ) by means of the pollutant reducing medium ( 112 ) pressurizable pressure tank ( 136 ), which is connected to the energy store ( 128 . 134 ). Dosing device ( 110 ) according to the preceding claim, wherein the shutdown device ( 126 ) is set up in the pressure tank ( 136 ) located pollutant reducing medium ( 112 ) in the event of a malfunction of the metering device ( 110 ) and / or a metering device ( 110 ), in particular in the event of a loss of power to the dosing device ( 110 ), with at least partial release of the energy of the energy store ( 128 . 134 ) from the pressure tank ( 136 ) to let go. Dosing device ( 110 ) according to one of the preceding claims, wherein the shutdown device ( 126 ) one with the energy storage ( 128 . 134 ) associated vacuum tank ( 138 ), wherein the shutdown device ( 126 ) is set up in the event of a malfunction of the metering device ( 110 ) and / or a metering device ( 110 ), in particular in the event of a loss of power to the dosing device ( 110 ), with at least partial release of the in the energy storage ( 128 . 134 stored energy the supply system ( 114 ) and / or the dosing module ( 116 ) at least partially, wherein the harmful substance-reducing medium ( 112 ) from the supply system ( 114 ) and / or the dosing module ( 116 ) at least partially into the vacuum tank ( 138 ) is sucked. Dosing device ( 110 ) according to the preceding claim, wherein the supply system ( 114 ) at least one supply line ( 120 ), wherein the vacuum tank ( 138 ) with the supply line ( 120 ) via a branch line ( 148 ) is connectable. Dosing device ( 110 ) according to the preceding claim, wherein the branch line ( 148 ) comprises a cross-section reducing element, in particular a throttle element ( 150 ). Dosing device ( 110 ) according to one of the three preceding claims, wherein the vacuum tank ( 138 ) comprises a compensating device to prevent expansion of the vacuum tank ( 138 ) recorded pollutant reducing medium ( 112 ) to compensate for a volume increase by freezing.