WO2011141502A1

WO2011141502A1 - Tank for storing an operating material

Info

Publication number: WO2011141502A1
Application number: PCT/EP2011/057597
Authority: WO
Inventors: Rolf BRÜCK; Jan Hodgson; Sven Schepers
Original assignee: Emitec Gesellschaft Für Emissionstechnologie Mbh
Priority date: 2010-05-12
Filing date: 2011-05-11
Publication date: 2011-11-17
Also published as: DE102010020200A1

Abstract

The invention relates to a tank (1) for storing a liquid operating material (2) for a motor vehicle (3), having a tank wall (18) and an interior (8) that is delimited by the tank wall (18), and at least one heating device (7) that is mounted through the tank wall (18) from outside and extends into the interior (8). The invention further relates to a method for producing a tank.

Description

Tank for storing a fuel

The invention relates to a tank for storing a fuel for a motor vehicle. The operation of a motor vehicle typically requires several liquid supplies that can freeze at low temperatures in their tanks. Such fuels are, for example, the fuel for operating an internal combustion engine, windscreen wiper water for cleaning the windows of the motor vehicle, coolant for operating the internal combustion engine or reducing agent for reducing harmful components in the exhaust gas of an internal combustion engine. In particular, the use of reducing agent for purifying exhaust gases of an internal combustion engine has recently gained considerable importance in the automotive sector. A frequently used process for exhaust gas purification, for which a reducing agent is required as an additional fuel of the motor vehicle, is the selective catalytic reduction (SCR) process. In this method, a reduction agent is supplied to the exhaust gas of the internal combustion engine, with which nitrogen oxide compounds (NOx) in the exhaust gas are effectively reduced within the exhaust system. The method of selective catalytic reduction is used in particular in exhaust systems of lean-burn internal combustion engines, such as diesel engines. These have an increased output of nitrogen oxide compounds.

For the implementation of nitrogen oxides in the context of the SCR process, in particular ammonia is used as the reducing agent. Ammonia is regularly not stored in the motor vehicle itself, but in the form of a so-called reducing agent precursor, ie a substance that is still (chemically) converted into ammonia (as needed). A frequently used reducing agent precursor is urea - Water solution. A 32.5% urea-water solution is available for this purpose under the trade name AdBlue and is widely used. The problem with the storage of urea-water solution in a tank is that it freezes at temperatures of about -11 ^° C. Such temperatures may occur during operation of a motor vehicle, especially during long periods of downtime in winter. On the one hand, a tank for a reducing agent must therefore be designed such that it is not damaged when the reducing agent stored in the tank freezes. In addition, it is necessary that after the start of the vehicle as quickly as possible liquid reducing agent in the tank is available. For this reason, it is known to provide in a tank for storing a reducing agent heating devices by means of which frozen reducing agent can be thawed.

The problem with such heaters is that they often represent a major cost factor both during installation and during operation. In addition, such heaters are maintenance-intensive. In addition, it was found that the freezing behavior or behavior behaves strongly dependent on the use or the position of the tank in the motor vehicle. In order to meet the above-mentioned criteria, the known heaters are usually designed much larger than is required for a variety of applications, whereby the energy demand and costs continue to rise. Consequently, there is a lack of a concept of how such heating devices introduce as much energy into the tank as is actually needed to thaw the frozen reducing agent. On this basis, it is the object of the present invention to at least partially alleviate the technical problems described in connection with the prior art. In particular, a particularly cost-effective and particularly easy to install tank for a fuel for a motor vehicle with an effective Heizvor- direction and a particularly advantageous method for energetically favorable positioning of a heater can be specified in a tank. These objects are achieved with a tank according to the features of patent claim 1 and with a method according to the features of patent claim 7. Further advantageous embodiments of the tank and the method are given in the dependent formulated claims. The features listed individually in the claims are combinable with each other in any technologically meaningful manner and can be supplemented by explanatory facts from the description, wherein further embodiments of the invention are shown. The invention therefore relates to a tank for storing a liquid fuel for a motor vehicle, comprising a tank wall and an interior, which is bounded by the tank wall, and at least one heater, which is mounted from the outside through the tank wall and extends into the interior.

The tank preferably has a tank wall made of plastic, wherein the tank in particular forms an enclosing (one-piece) tank wall. The operating fluid (under normal operating conditions or room temperature) can now be permanently stored in the interior of the tank. The liquid fuel is preferably a reducing agent or a reducing agent precursor for reducing pollutant components in the exhaust gas of an internal combustion engine. For example, the fuel may be a urea-water solution. For mounting the at least one heating device from the outside through the tank wall, the tank wall preferably has a corresponding (second) mounting opening, through which the at least one heating device is mounted. In addition to the at least one heating device, a delivery device for the liquid operating material may also be provided in the tank. The conveying device can be provided, for example, in a metallic housing on the tank wall, which is positioned in a (only) provided (separate or first) mounting opening of the tank.

The at least one heating device is preferably an electrically operable or controllable heating device which has at least one PTC heating resistor (PTC = positive temperature coefficient) as heating element. Such a heating resistor is able to regulate its heating power over a predetermined temperature range from the heating resistor itself and is thus particularly advantageous when just the energy needed for thawing is to be introduced into the operating material.

In a further embodiment of the heating device, this may also be designed in the manner of a liquid heater, in which a hot fluid flows through a heating loop. As a heating fluid, for example, the cooling water of the internal combustion engine of a motor vehicle can be used.

It is likewise possible for the at least one heating device to comprise a so-called heat pipe ("heat pipe") Heat pipes generally contain a hermetically encapsulated volume, usually in the form of a tube, which is filled with a working medium (eg water). It fills the volume to a small extent in the liquid state, and to a large extent in the vapor state, each containing a heat transfer surface for a heat source (near the tank wall or outside the tank wall) and a heat sink (inside the tank or opposite the heat source) During a heat input, the working medium begins to evaporate, causing the pressure in the vapor space to increase locally above the liquid level, resulting in a small pressure gradient within the heat pipe, so that the resulting vapor flows in the direction of the heat sink where it will flow Temperature z. B. the frozen reducing agent (heat sink) condensed. The previously recorded latent heat is released again. The now liquid working medium then returns to the evaporator (heat source) by gravity or by a capillary force.

Accordingly, in other words, this at least one heating device is a local, retrofitted, heat source positioned at a predetermined point through the tank wall for the targeted and effective thawing of frozen fuel in the tank interior. This means, in particular, no surface heating extending along the tank wall, which practically also forms an interface with the environment over a large area (and optionally may additionally be provided). Rather, the heating power is deliberately introduced far into the interior of the tank by means of the at least one heating device. For this purpose, a plurality of such heating devices may be provided, so that a predetermined distribution of the heaters is reached deep into the interior. For this purpose, the heating devices can also be designed differently, in particular with regard to their nature, length, orientation, heating power, etc.

This embodiment of the tank in particular allows retrofitting with demand-driven, efficient heating devices. The tank is particularly advantageous if the at least one heating device is designed with at least one of the following configurations:

- in the manner of a staff; and

- in the manner of a plate. It has been found that such designed heaters can be particularly easily and quickly mounted in the tank according to the invention. For such configured heaters appropriately shaped (second) mounting holes in the tank or a tank wall of the tank are advantageous, through which the heaters of can be mounted outside. A running in the manner of a rod heater has a direction in which it has a relation to the other two spatial directions significantly increased length. A heater designed in the manner of a plate has two directions, in which it has a considerably increased length compared to a third direction. Preferably, the at least one heater has a cross-sectional shape and a length perpendicular to the cross-sectional shape. The cross-sectional shape substantially corresponds to the shape of the second mounting opening, through which the at least one heating device can be mounted.

Furthermore, the device according to the invention is advantageous if the at least one heating device is detachably and fluid-tightly connected to the tank wall. It is particularly advantageous to introduce the heater through the second mounting hole in the tank, or to mount in the tank when the second mounting hole is located in the bottom of the tank in the tank wall. In particular, it is then important for the heating device in the second assembly opening to close in a fluid-tight manner to the tank wall, so that no leakage of fuel from the tank occurs. Such a detachable integration of the at least one heating device facilitates repair measures or the integration of other heating devices if the freezing behavior or the thawing behavior of the motor vehicle subsequently changes. According to a further development, it is also proposed that the tank has a height and the at least one heating device has a length, and that the length extends at least over 40% of the height. Preferably, the length even extends over at least 70% or even over 100% of the height of the tank. When the liquid feedstock freezes in a tank, a self-contained blanket of frozen feedstock regularly forms on the surface of the formerly liquid feedstock. When commissioning the motor vehicle usually starts a conveyor for the fuel to promote this out of the tank. This can then be a negative pressure below the closed ceiling to produce frozen fuel in the tank. This negative pressure prevents further delivery of fuel from the tank. A heater extending over a large portion of the height of the tank is capable of melting an opening in such a closed ceiling, regardless of the height of the closed ceiling in the tank. If for reasons of stability (for example, in motor vehicles for the off-road area) no very long heating device may be desired, this z. B. from different locations of the tank (side, ceiling, floor) are designed with a shorter length, wherein it is preferred that these together at least over 70% or even 90% of the height of the tank extend.

Further advantageous is the tank according to the invention, if the at least one heater is at least partially permeable to liquid fuel. For this purpose, for. As openings, pores, channels or the like may be provided, which optionally also allow a flow through the heater with liquid fuel. In particular, a heating device designed in the manner of a plate represents a considerable flow resistance for operating fluid in the tank. For this reason, it is advantageous to carry out the heating device permeable to liquid operating fluid at least in certain areas.

In addition, it is also considered advantageous if the at least one heating device forms a heatable cage around the conveyor device. In a manner of a self-contained or circumferential cage or in the manner of a self-contained or circumferential wall around a conveyor device around designed heater, the heater separates the conveyor from the rest of the interior of the tank. A partial permeability of the heating device for liquid fuel is then required so that fuel from the remaining interior of the tank can get to the conveyor. According to a further aspect of the invention, a method is proposed for positioning a heating device in a tank for storing a liquid fuel, which comprises at least the following steps:

a) filling the tank with the fuel;

b) freezing the filled tank under conditions of use;

c) detecting the freezing behavior of the filled tank;

d) producing a second mounting opening in the tank wall; and e) mounting the heater at the second mounting opening through the tank wall such that the heater extends into an interior of the tank.

The term "conditions of use" here means, in particular, the conditions that can actually occur during operation of the motor vehicle, for example the installation position of the tank, the distribution of the fuel in the tank, the temperature distribution in the vicinity of the tank and the like Preferably, therefore, to carry out step b), a tank is provisionally mounted in a motor vehicle and exposed for a predetermined period (possibly repeated with different levels and / or different operating conditions of the motor vehicle as long / short / repeated engine operation) appropriate cold This helps to ensure that actual operating conditions are in place.The environment of the tank in the motor vehicle can play a significant role in the freezing behavior of the tank.

The "freezing behavior" describes, for example, where the fuel first freezes or how the ice forms in the tank, in particular until the fuel is completely frozen, thus enabling critical areas to be identified which are eliminated by the subsequent location of heaters In particular, for example, the sampling point and / or a venting opening can be free for a longer period of (repeated) frost exposure to be held by ice. The freezing behavior of the tank is preferably monitored by appropriate monitoring methods.

The monitoring can take place for example by means of temperature sensors at critical points in the tank. For this purpose, temperature sensors can be provided at locations where a particularly rapid freezing of the fuel is expected. It is also possible to provide several temperature sensors. For example, these may be arranged in the immediate vicinity of a location at which a particularly rapid freezing is expected with a predetermined pattern. It is also possible to provide a three-dimensional grid of temperature sensors for monitoring the freezing behavior in the entire tank. In the monitoring of the freezing behavior, temperature sensors outside the tank can also be included and / or temperature sensors on a conveyor module for conveying fuel out of the tank. Further information, such as the vehicle speed and / or the level, can also be included. All this information can be processed in a suitable model of the freezing behavior of the fuel tank to determine the actual freezing behavior of the tank in a specific application. In particular, such a model can be an energy model which takes into account the heat energy stored in the operating fluid and / or the heat flows out of the tank or into the tank.

Of course, the "thawing behavior" may also be analyzed to pre-determine positions for steps d) and e) to achieve an effective heating system The second mounting opening in the tank wall may be, for example, by means of a saw or by drilling into the tank wall In addition, a preparation of the tank wall may be required in the region of the second mounting opening, so that here the at least one heating device is introduced and in particular also one fluid-tight connection between the tank wall and the heater can be generated.

The method according to the invention is particularly advantageous if the second assembly opening is prepared in step d) where in step c) a particularly rapid freezing of the tank was determined. This is exactly where frozen reducing agent is first in the tank. Since complete freezing of the fuel in the tank will rarely occur on a regular basis, frozen fuel is often only available at this point. For this reason, a heating device introduced there can be operated particularly energy-saving.

The advantages and special configurations shown for the method according to the invention can be transferred in an analogous manner to the tank according to the invention. The same applies to the particular advantages and embodiments described for the tank according to the invention, which are applicable and transferable to the method according to the invention.

The inventive method is particularly suitable for the production of a test tank according to the invention. With such a test tank, the freezing behavior of the tank can be examined with and without a heater and a particularly advantageous position for a heater in the tank can be determined. Different mounting positions of the heater (s) in the tank can be investigated without having to manufacture the tank directly with the corresponding mounting holes. For series production of tanks according to the invention, the ideal installation position for a heating device determined by the method according to the invention for a particular tank geometry can be adopted and the tanks can be manufactured directly with corresponding assembly openings at the determined position, without previously freezing under operating conditions for each individual tank he follows. The implementation of the method according to the invention for producing a tank according to the invention can also be adapted to a specific type of motor vehicle. Depending on the type of motor vehicle, the installation position of the tank according to the invention, the immediate surroundings of the tank according to the invention in the motor vehicle and the conditions of use may be different. Therefore, the same tank in different vehicles may have a different freezing behavior. The inventive method makes it possible to detect these differences and to take into account in the positioning of a heater in the tank.

The invention has particular application in a motor vehicle, comprising an internal combustion engine and an exhaust gas treatment device for cleaning the exhaust gases of the internal combustion engine and a tank according to the invention with a heating device and a control unit, wherein the exhaust gas treatment device has a supply device for a fuel, which is stored in the tank and the control unit is adapted to control the heating device of the tank. In this case, a liquid urea-water solution is preferably added to the exhaust gas as the operating substance. In particular, the motor vehicle has a tank, which is produced by the method according to the invention.

The invention and the technical environment will be explained in more detail with reference to FIGS. The figures show particularly preferred embodiments, to which the invention is not limited. In particular, it should be noted that the figures and in particular the illustrated proportions are only schematic. 1 shows a first embodiment variant of a tank according to the invention in a vertical sectional view,

2 shows a second embodiment of an inventive

Tanks in a vertical section view, 3 shows a third embodiment variant of a tank according to the invention in a vertical sectional view, FIG. 4 shows a fourth variant of an embodiment according to the invention

Tanks in a horizontal sectional view,

5 shows a fifth embodiment of an inventive

Tanks in a horizontal sectional view, and

Fig. 6: a motor vehicle having a tank according to the invention.

Fig. 1, Fig. 2 and Fig. 3 show three different embodiments of a tank 1 according to the invention for a liquid operating material 2 (in particular urea-water solution), in which in a first mounting opening 4, a conveying device 6 for the Fuel 2 is mounted. In addition, a heater 7 is mounted in a second mounting hole 5. The heating device 7 extends with a length 10 over a significant portion of the height 11 of the tank 1. The heating device 7 is designed in the manner of a rod 26. The heating device 7 has a PTC heating element 23 for the conversion of electrical energy into thermal energy and has an electrical connection 22 via which it can be supplied with electrical energy. The conveyor device 6 has at least one system heater 20 (for heating the devices in the conveyor and / or for heating the operating material arranged in the external environment) and has a line connection 21 through which the operating material 2 can be conveyed out of the tank , The tank wall 18 of the tank 1 defines the interior 8 of the tank 1. In the interior 8, the fuel 2 (in the illustrated figures) is largely in frozen form. The heating device 7 has melted along its extension a channel 25, through which a pressure equalization between the environment and a freely around the conveyor 6 molten cave 29 can take place. In the first embodiment variant of the tank according to the invention according to FIG. 1, both the heating device 7 and the conveying device 6 are mounted in a bottom 9 of the tank.

2, the conveyor 6 extends from the bottom 9 of the tank 1 in the interior 8 of the tank 1 inside, while the heater 7 from above (the ceiling of the tank) into the interior. 8 of the tank 1 extends into it. The heating device 7 of FIG. 2 is executed angled. Thus, the heating device 7 can also reach areas of the interior 8 of the tank 1 that are far away from the second assembly opening 5. The heating device 7 is preferably designed so that it can be introduced into the tank 1 through the second mounting opening 5 despite the bend 30. The heater 7 may also have a plurality of creases 30 or other shapes.

In the third variant of the inventive tank 1 according to FIG. 3, the conveying device 6 extends through the bottom 9 into the interior 8 of the tank 1, while the heating device 7 extends from above into the interior 8 of the tank 1. The conveying device 6 has a first coupling part 13, and the heating device 7 has a second coupling part 14. The first coupling part 13 and the second coupling part 14 can be coupled together, so that a firm connection between the heating device 7 and the conveying device 6 is formed. Thus, increased stability of the tank 1 can be achieved because the tank 1 is stabilized by the conveying device 6 and the heating device 7. FIG. 4 shows a fourth embodiment variant and FIG. 5 shows a fifth embodiment variant of a tank 1 according to the invention. Here, a horizontal sectional view through the tank 1 is illustrated. In both variants, each of the tank 1 can be seen. The tank wall 18, which limits the interior space 8, is cut. The viewer can see from above the bottom 9 of the tank 1. Also visible is the introduced into a first mounting opening 4 conveyor 6 with its housing 19 and introduced into second mounting holes 5 heaters 7, each having a PTC heating element 23.

In Fig. 4, a heater 7 in the manner of a plate 27 is executed. The other heating device 7 is designed in the manner of a rod 26. As a special feature in FIG. 5, a heating device 7 arranged in the manner of a cage 27 in the manner of a cage around the conveying device 6 is shown. The cage 12 is designed semicircular around the conveying device 6. The heating device 7 has openings 24 through which fuel can flow from the interior 8 of the tank 1 to the conveying device 6.

6 shows a motor vehicle 3 having an internal combustion engine 15 and an exhaust gas treatment device 16 for cleaning the exhaust gases of the internal combustion engine 15. The exhaust gas treatment device 16 has an adding device 17, which is supplied with fuel from a tank 1 according to the invention by a conveying device 6. The tank 1 according to the invention has a heating device 7, which can be controlled by a control unit 28.

LIST OF REFERENCE NUMBERS

1 tank

2 fuel

3 motor vehicle

4 first mounting hole

5 second mounting hole

6 conveyor

7 heating device

8 interior

9 floor

10 length

11 height

12 cage

13 first coupling part

14 second coupling part

15 internal combustion engine

16 exhaust treatment device

17 adding device

18 tank wall

19 housing

20 system heating

21 pipe connection

22 electrical connection

23 PTC heating element

24 opening

25 channel

26 staff

27 plate

28 control unit

29 cave

30 kink

Claims

claims

1. tank (1) for storing a liquid fuel (2) for a motor vehicle (3), comprising a tank wall (18) and an inner space (8) which is bounded by the tank wall (18), and at least one heating Device (7) which is mounted from the outside through the tank wall (18) and extends into the interior space (8).

Tank (1) according to claim 1, wherein the at least one heating device (7) is designed according to at least one of the following configurations:

in the manner of a rod (26); and

like a plate (27).

Tank (1) according to one of the preceding claims, wherein the at least one heating device (7) is detachably and fluid-tightly connected to the tank wall (18).

Tank (1) according to one of the preceding claims, wherein the tank (1) has a height (11) and the at least one heating device (7) has a length (10), and the length (10) at least over 40% of the height ( 11).

Tank (1) according to one of the preceding claims, wherein the at least one heating device (7) is at least partially permeable to liquid fuel (2).

Tank (1) according to one of the preceding claims, wherein the at least one heating device (7) forms a heatable cage (12) around the conveying device (6).

7. A method for positioning a heating device (7) in a tank (1) for storing a liquid fuel (2) comprising at least the following steps: a) filling the tank (1) with the operating material (2);

b) freezing the filled tank (1) under conditions of use; c) detecting the freezing behavior of the filled tank (1);

d) producing a second mounting opening (5) in the tank wall (18); and

e) mounting the heating device (7) at the second mounting opening (5) through the tank wall (18), so that the heating device (7) extends into an inner space (8) of the tank (1).

A method according to claim 7, wherein the second mounting opening (5) in step d) is prepared where in step c) a particularly rapid freezing of the filled tank (1) has been determined.

Motor vehicle (3) comprising an internal combustion engine (15) and an exhaust gas treatment device (16) for cleaning the exhaust gases of the internal combustion engine (15) and a tank (1) with a heating device (7) according to one of the claims 1 to 6, and a control unit ( 28), wherein the exhaust gas treatment device (16) has a supply device (17) for a fuel (2) which is stored in the tank (1) and the control unit (28) is adapted to control the heating device (7) of the tank (1 ) to control.