DE102013008835A1 - Motor vehicle with an additive container, in particular for an SCR reducing agent - Google Patents

Abstract

The invention relates to a motor vehicle (300), comprising - an exhaust line (150), - a container (100) for receiving a liquid additive, - a delivery unit (120) for delivering the liquid additive into the exhaust line (150) and - a plurality Wheel houses (200). According to the invention it is provided that the container of the container (100) is arranged in one of the wheel houses (200) of the motor vehicle.

Description

The invention relates to a motor vehicle with an exhaust pipe, a container for receiving a liquid additive, a conveyor unit which is capable of conveying the liquid additive into the exhaust pipe, and a plurality of wheel arches.

Internal combustion engines that are operated intermittently or predominantly with a lean air-fuel mixture produce nitrogen oxides NO _x (mainly NO ₂ and NO), which require NO _x -reducing measures. A motor measure to reduce the NO _x -Roh emission in the exhaust gas is the exhaust gas recirculation, in which a part of the exhaust gas of the internal combustion engine is returned to the combustion air, whereby the combustion temperatures are lowered, and thus the NO _x -ausstung is reduced. However, the exhaust gas recirculation is not always sufficient to comply with legal NO _x limits, so in addition an active exhaust aftertreatment is required, which reduces the NO _x -Edemission. A known NO _x -Abgasnachbehandlung provides for the use of discontinuously operated NO _x storage catalytic converters, which store in lean operation (at λ> 1) nitrogen oxides in the form of nitrates and at short intervals with a rich exhaust gas atmosphere (λ <1) the stored nitrogen oxides Desorb and in the presence of existing in the rich exhaust reducing agent HC and H ₂ to nitrogen N ₂ reduce.

As a further approach to the conversion of nitrogen oxides in exhaust gases mlauflauffähiger internal combustion engines, the use of catalyst systems is known which operate on the principle of selective catalytic reduction (SCR). These systems comprise at least one SCR catalyst (also referred to as DeNOx catalyst), which converts the nitrogen oxides of the exhaust gas into nitrogen and water in the presence of a reducing agent continuously supplied to the exhaust gas, usually ammonia NH ₃ . In this case, the ammonia can be added in gaseous form or as aqueous ammonia solution to the exhaust gas stream. Alternatively, a NH ₃ -release precursor compound is often used, is obtained from the ammonia by way of thermolysis and hydrolysis. The currently most common precursor compound for ammonia is urea, which is used in the form of solid urea pellets or an aqueous urea solution.

Regardless of the type of reducing agent used, it must be stored in the vehicle and carried along. In the case of liquid reducing agents or reducing agent solutions reducing agent containers are provided for this purpose, which are refueled via a filling line. Space reasons make it sometimes necessary that the filling line opens into a lower region of the reducing agent container, which in turn may result in problems in the escape of the displaced by the inflowing reductant air during filling of the container. In order to use the available space effectively, it is often necessary to adapt the shape of the container to the space. This results in unfavorable container shapes, such as flat and / or irregular shapes (eg L-shape), which in turn have an unfavorable effect on level and temperature measurement. In addition, there may be limited ice strength, which is the freezing point at -11 ° C in the urea solution commonly used as a reducing agent carrier. In order to solve the problems underlying the container shape, the use of baffles to reduce sloshing noise and the use of built-in heating mats in addition to the heating element of the conveyor unit is known. The latter is intended to ensure the sustainable dosing readiness with frozen reducing agent.

In order to ensure the supply of the liquid reducing agent in the exhaust pipe, usually a conveyor unit is provided which comprises a feed pump and a filtration unit. In addition, the containers are typically equipped with an integrated level and temperature sensor, as well as a heating element. Through this equipment, the space requirement of the entire unit increases significantly, which is problematic in view of the limited number of possible installation locations in the motor vehicle.

Stricter legal requirements for exhaust gas composition, as well as the desire to greatly reduce the container size, lead to the fact that the reducing agent supply in passenger cars can no longer be filled exclusively within the service interval. Constructions in which the container is difficult to access, such as in the subfloor ( DE 10 2007 019 912 A1 ) are therefore no longer appropriate.

Also, the attempt to divide the stock on a less accessible large container in the trunk and a more accessible smaller container in the engine compartment, as in DE 10 2007 005 006 A1 described, are insufficient. Rather, the filling of the container by the driver of the vehicle must be quick and easy. In order to improve the accessibility during filling, it is also known to mount the container in the vicinity of a wheel house in such a way that the filler neck protrudes into the wheel arch ( DE 10 2008 020 213 A1 ).

The invention is based on the object to provide a motor vehicle available, in which the reducing agent container is arranged in the vehicle so that it by the driver in regular, For example, when refueling usual, intervals in a simple and comfortable way can be filled. Ideally, it should be ensured that all supply, exhaust and vent lines can be formed as short as possible and siphon-free.

This object is achieved by a motor vehicle having the features of claim 1.

The motor vehicle according to the invention comprises an exhaust pipe, a container for receiving a liquid additive, a conveying unit for conveying the liquid additive into the exhaust pipe, and a plurality of wheel arches. According to the invention it is provided that the container is arranged in one of the wheel arches of the motor vehicle.

The arrangement of the container in the wheel arch, it is possible to make the supply and discharge very short. Due to space constraints, it is often unavoidable in known vehicles that the supply and discharge lines pass through local low points with regard to their line characteristics and thus form siphon sections, for example, in order to bypass vehicles of the vehicle. The inventive positioning in the wheel arch, however, allows a siphon-free installation of the derivatives due to the relative height to the exhaust pipe. In addition, the container is easily accessible. By accessible arranged container ensures that refilling and / or replacement of the container is possible without workshop visit and can take place independently of a service interval. Thus, a simple refilling by the user when needed is possible.

In a preferred embodiment of the invention, it is provided that the container is arranged in that wheel housing, which is in the immediate vicinity of a filling device, in particular a tank trough, for filling a fuel tank of the motor vehicle. In particular, it is a wheel house of the rear axle of the vehicle. This arrangement has the advantage that the space is already adapted to the requirements of piping systems of liquid media, such as fuel, and thus can ensure a siphon-free installation.

The arrangement in the vicinity of the filling device for fuel also makes it possible to arrange a filler neck for filling the container, preferably directly in the filling device for fuel, in particular in a common tank trough. This advantageously enables the filling of the container in the intervals of the fuel fillings. In addition, no additional tools are needed. Rather, the user is familiar with this process and can incorporate the additional filling of the container in a simple manner in the usual routines.

To make this possible, the dimensions of the container are preferably chosen so that a volume can be stored, which covers the needs of the liquid additive during the consumption of a tank filling. A preferred range is between 6 and 12 liters. This volume is significantly lower compared to currently used concepts in which the container volume is designed for filling or replacement only at the service intervals.

In the described embodiment of the filler neck of the container in the immediate vicinity of the filler neck of the fuel system, the invention provides in a preferred embodiment, a separation between the two filler neck, which prevents the simultaneous filling. Rather, only one filling is always accessible. This prevents accidental contamination of the other system.

In a preferred embodiment of the invention, it is provided that the discharges of the container open into an exhaust pipe of the motor vehicle. Preferably, the mouth is upstream of a catalyst. In this case, an SCR catalyst for exhaust gas purification is particularly preferred. The advantage resulting from this arrangement is that the container is preferably filled with a liquid additive which provides the necessary for the operation of the SCR catalyst reducing agent.

In a further preferred embodiment of the invention, therefore, the liquid additive is a reducing agent. In the context of the present invention, the term "reducing agent" also means a precursor compound (reducing agent carrier) which releases the actual reducing agent (in particular ammonia NH ₃ ) through further process steps. In particular, in the context of the present invention, the liquid reducing agent or the liquid reducing agent solution also includes solutions of urea or ammonia in a suitable solvent, in particular water.

Since it can come in the storage of a liquid additive, especially when using a reducing agent, especially in the urea solution, a chemical decomposition and decomposition products of all aggregate states may occur, a preferred embodiment of the invention provides a closure for closing the filler neck before and after Filling in front. This can be both a manually closable lid, as well as a self-closing mechanism. Another The advantage of closing the filler neck is the prevention of contamination by the fluid of the other system.

The container is to be designed so that it is suitable for the storage of the reducing agent described above. In addition to suitable materials, this also includes the container shape. The container in the motor vehicle according to the invention is preferably designed in a high shape. This is to be understood as meaning a ratio of height to length of the base area in the case of a rectangular container or a ratio of height to diameter of the base area of a cylindrical container which is greater than one. The formation of the container in a high form has the advantage that the functional requirements of the container can be implemented without expensive additional measures. Specifically, this means that, for example, installed for a level transmission to a display panel sensors can detect the level with a much higher accuracy than in a flat design of the container. In addition, the use of baffles is not necessary because the surge of liquid is greatly reduced in a high container shape, in particular a cylindrical, due to lower moving masses. In order to ensure a sustainable metering readiness is also often necessary in flat and / or irregularly running containers to introduce specific heating mats to thaw, especially in the case of filling with urea solution, the frozen reducing agent and make it dosed. In the case of frozen liquid, the high form is further preferred, since, in particular in the case of irregular containers, the expansion in the frozen state can lead to the container walls being stressed too much. In particular, in the case of the L-form, which is typical for known reducing agent containers, an expansion volume of approximately 10% can not be maintained throughout the container, since this is physically possible only at the top of the container.

A preferred embodiment of the container provides for the attachment of at least one temperature sensor and / or level sensor and / or at least one heating element. The sensor allows monitoring of the liquid additive in such a way that on the one hand comes to notify in a display panel about necessary refilling. On the other hand, when a temperature sensor is used in the case of a solid or solidifying additive, activation of the same is triggered by a sensible connection to the heating element, and thus the metering capability of the additive is restored.

In gasoline vehicles, it is common practice to mount an activated carbon filter to form fuel vapors in a rear wheel arch. If, as described above, the container accommodated in a rear wheel arch, provides a preferred embodiment of the invention, the attachment of the activated carbon filter and the attachment of the container match each other so that the body side, the same fastening device can be used. The advantage here is that for diesel vehicles that do not use an activated carbon filter, the same body type can be used and therefore no different processes for diesel or gasoline vehicles are necessary in the manufacture of the body.

The metering of the liquid additive is preferably carried out by means of a delivery unit, in particular comprising a feed pump, a sump, further a filtration unit, which is formed for example as a sieve. Both a flexible arrangement of the feed pump on the container and a separate external feed pump is preferred. In a preferred embodiment of a fixedly connected pump, a recess is provided on the container, which is adapted in shape and size to the conveyor unit. Thus, the space next to the conveyor unit is used as a container volume. The use of an external pump has the advantage that even with the assembly of the container in the wheel arch, the preferred volumes of up to 10 liters can be achieved. The total package of container and fixed integrated conveyor unit hitherto made it difficult to arrange useful container sizes in the wheel arch. Furthermore, standardized container shapes can be used.

The invention will be explained below in embodiments with reference to the accompanying drawings. Show it:

1 a schematic representation of a motor vehicle with a container and an exhaust pipe according to a first embodiment of the invention,

2 a schematic representation of a container for storing a liquid additive with delivery unit according to a preferred embodiment; a) side view; b) view from the bottom of the container, and

3 a schematic representation of the arrangement of a filling device according to a first embodiment of the invention.

1 shows a total of 300 designated motor vehicle. Here is the side of the vehicle 200 shown, on which a filling device of a fuel tank, not shown here, is arranged. The car 300 has four wheel arches 200 two of which are visible here.

The vehicle has as a drive source in the front engine compartment on an internal combustion engine, not shown here, which is in particular a diesel engine. A likewise not shown fuel tank of the internal combustion engine, via a here designed as tank tank filling 180 refueled.

The internal combustion engine is equipped with an exhaust pipe 150 fluidically connected, the one SCR catalyst 151 houses. This is designed to selectively convert nitrogen oxides of the exhaust gas of the internal combustion engine in the presence of a reducing agent catalytically. As a reducing agent in the present example, an aqueous urea solution is used, which in a reservoir 100 is stored. The urea solution is conveyed by means of a conveyor 120 from the container 100 over a line 140 to a controllable metering device 141 promoted, which is a dosage of urea solution in the exhaust pipe 150 upstream of the SCR catalyst 151 performs. The urea decomposes by way of hydrolysis and thermolysis to ammonia, which as the actual reducing agent in the catalyst 151 acts.

According to the invention, the storage container 100 in one of the wheel arches 200 arranged. It is, as shown here, that wheelhouse 200 preferred, which is in close proximity to the tank trough 180 located. The container is via a filler neck 110 refueled. The filler neck is located as well as a fuel filler neck in the tank recess. When refueling the container, the reducing agent passes through a with the filler neck 110 connected filling tube 111 in the container 100 , The level of the reducing agent in the container is with a level sensor 102 monitored in the lower part of the container. In addition, there is a temperature sensor 103 near the level sensor 102 appropriate. An activatable heating element also mounted in the container 101 , serves to warm and thaw the solution if the temperature drops below the freezing point of the solution which is reached at urea solution at -11 ° C. The heating element ensures that dispensing readiness can be established at any ambient temperature.

Above the maximum level of the container is a vent 130 arranged. The vent is in the tank well 180 guided.

Below is a possible embodiment of the container 100 with integrated conveyor unit 120 explained in more detail.

2 shows in a preferred embodiment of the invention, the container 100 with a permanently integrated conveyor unit 120 , Shown is a tall shape of a rectangular container. This means that the ratio between the height h of the container to the length l or width b of the base area is greater than one.

The container is by means of several fastening tabs 104 attachable to a body of the vehicle or a fastening device.

For optimal use of space is in the container a recess 124 let in, the shape and size of which is designed to be the conveyor unit 120 can record. The conveyor unit is arranged within this recess.

The delivery unit comprises, in addition to a pump, a heating element, not shown, as well as a temperature sensor, also not shown, to monitor and prevent freezing of the reducing agent in the pump. The reducing agent is passed through a suction line 125 from a pump sump 122 sucked. The pump sump 122 is as a depression of the container 100 formed at its lowest point. To retain solid components is in the sump 122 in front of the intake pipe 125 a filtration unit 123 arranged, which may be formed in the form of a sieve. An upper outlet of the delivery unit comprises a connection to the discharge, not shown. About the derivative, the reducing agent is conveyed by means of the metering device in the exhaust pipe.

3 shows a section 1 , As in 1 shown is the container 100 in that wheelhouse 200 arranged in the motor vehicle, which is in close proximity to the filling tank running as a tank.

Shown is a detailed embodiment of the tank trough 180 , The tank trough 180 is closed by a flap, not shown here, which is articulated pivotally on the side of the tank recess shown here on the right. Arranged in the tank recess is the fuel filler neck 160 that has a filler pipe 161 is connected to the fuel tank, not shown. Also in the tank well is the filler neck 110 for the container 100 , The filler neck for the container is designed differently than the fuel filler neck 160 , in particular, significantly smaller than this formed, so that a fuel nozzle for fuel not in the filler neck 110 can be introduced. A preferably screw-down lid closes the filler neck 110 to additionally prevent contamination by fuel.

Through the filler neck 110 the reducing agent passes through a filling tube 111 in the container. The vent 130 returns gases that are above the reducing agent to the tank recess to prevent the formation of overpressure. The filling tube 111 as well as the vent 130 are arranged so that no local low points (siphons) arise in which liquid can accumulate and a filling and / or venting is hindered.

LIST OF REFERENCE NUMBERS

100

container

101

heating element

102

level sensor

103

temperature sensor

104

mounting tabs

110

filler pipe

111

filling pipe

120

delivery unit

121

connection

122

sump

123

filter unit

124

recess

130

vent

140

heated pipe

141

metering

150

exhaust pipe

151

SCR catalyst

160

fuel filler

161

fuel filler pipe

180

Filling device (tank recess)

200

wheelhouse

300

motor vehicle

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102007019912 A1 [0006]
• DE 102007005006 A1 [0007]
• DE 102008020213 A1 [0007]

Claims (9)

Motor vehicle ( 300 ), comprising - an exhaust pipe ( 150 ), - a container ( 100 ) for receiving a liquid additive, - a conveyor unit ( 120 ) for conveying the liquid additive into the exhaust pipe ( 150 ) and - a plurality of wheel arches ( 200 ), characterized in that the container ( 100 ) in one of the wheel arches ( 200 ) of the motor vehicle is arranged. Motor vehicle according to claim 1, characterized in that the container is mounted in that wheel housing, which in the vicinity of a filling device ( 180 ), in particular a tank well, for filling a fuel tank of the motor vehicle is arranged. Motor vehicle according to claim 2, characterized in that a filling nozzle ( 110 ) for filling the container in the filling device ( 180 ) is arranged for the fuel of the motor vehicle. Motor vehicle according to one of the preceding claims, characterized in that the exhaust pipe an SCR catalyst ( 151 ) and a feed of the additive upstream of the SCR catalyst opens into the exhaust pipe. Motor vehicle according to one of the preceding claims, characterized in that it is the additive is a reducing agent, preferably comprising urea in solution. Motor vehicle according to one of the preceding claims, characterized in that the container ( 100 ) is designed such that its height is greater than the length of a rectangular base or the diameter of a round base. Motor vehicle according to one of the preceding claims, characterized in that the container ( 100 ) with at least one element selected from the group of temperature sensors ( 103 ), Level sensor ( 102 ) and / or heating element ( 101 ) Is provided. Motor vehicle according to one of the preceding claims, characterized in that the container ( 100 ) by means of a in the wheel arch ( 200 ) arranged fastening device ( 104 ) adapted to selectively fix the container or an activated carbon filter. Motor vehicle according to one of the preceding claims, characterized in that the conveyor unit ( 120 ) on the container, in particular in a recess ( 124 ) of the container is attached.

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