DE102016206073A1 - Motor vehicle reduction liquid tank with thermal insulation and motor vehicle with such a reduction liquid tank - Google Patents

Abstract

A motor vehicle reducing liquid tank (310), which is designed in particular for storing and removing aqueous urea solution, with a tank interior (333) surrounded by a tank wall (330) to provide a receiving volume, wherein the tank wall (330) has a filling opening (314) Introduction of reducing liquid in the tank interior (333) and an outlet opening for removal of reducing liquid from the tank interior (333), wherein the tank wall (330) at least partially thermal insulation (346, 352), characterized in that the thermal insulation (346) is formed from porous material (352) and / or from at least one gas-filled cavity (342) between two in the thickness direction of the tank wall (330) spaced apart part walls or / and filled plastic, wherein the filler material has a lower thermal conductivity as the plastic.

Description

The present invention relates to a motor vehicle reduction liquid tank, which is designed in particular for storage and removal of aqueous urea solution, with an enclosed by a tank wall to provide a receiving volume tank interior, wherein the tank wall a filling opening for introducing reducing liquid into the tank interior and an outlet port for removal of reducing fluid from the tank interior, and wherein the tank wall at least partially has a thermal insulation.

A generic motor vehicle Reduktionsflüssigkeitstank is from the DE 10 2010 004 612 A1 known. This document teaches to delineate a chamber in the tank interior of the tank volume which can be filled with reducing fluid and to arrange components for conveying the fluid out of the tank to an injection point in this chamber. The document further teaches to equip the chamber walls with unspecified thermal insulation. However, this publication does not disclose boundary walls of the tank wall - ie those walls of the tank, the one fillable with reducing liquid volume fraction of the tank interior from the rest of the vehicle compartment, in which the reduction liquid tank is arranged - equipped with thermal insulation.

From the EP 1 473 447 B1 Another generic motor vehicle reduction liquid tank is known, which can be provided with a voltage applied externally to the tank wall and the tank completely or partially surrounding thermal insulation. The thermal insulation is not specified in this document.

Already the two cited generic publications, the technical problem underlying that reducing liquid, which is injected for the reduction of nitrogen oxides in an exhaust system of an internal combustion engine, at temperatures that are not too far below -10 ° C, freezes, which complicates a nitrogen oxide reduction or impossible. The currently most commonly used reducing fluid is urea aqueous solution, which freezes at about -11 ° C under normal atmosphere of 1013 hPa.

To avoid or delay the freezing many other measures have been proposed in addition to arranging a thermal insulation, such as the inclusion of a heater in the tank interior or on the tank wall (see also the EP 1 473 447 B1 or the DE 10 2010 004 612 A1 ). Further, heating has been proposed by approaching the mounting location of the reducing fluid tank to vehicle components which heat up strongly during driving, such as exhaust manifolds. However, the latter possibility delays freezing only if the vehicle is parked at low outside temperatures. If the vehicle is parked for a long period of time, the components that are warmed up during operation also cool down considerably so that they no longer give off heat to the environment.

The present invention is also fundamentally concerned with the problem of delaying or preventing the undesirable freezing of reducing fluid in a tank received in a motor vehicle. It is an object of the present invention to improve the aforementioned known motor vehicle reduction liquid tanks in their ability to delay or avoid freezing of reducing liquid, in particular of aqueous urea solution.

This object is achieved by a generic motor vehicle reduction liquid tank, as described above, in which the thermal insulation is formed of porous material and / or at least one gas-filled cavity between two in the thickness direction of the tank wall with spaced apart part walls and / or made of filled plastic, wherein the filler material has a lower thermal conductivity than the plastic.

In the case of porous material, very small gas volumes are located between the outside of the tank wall facing away from the interior of the tank and the inside of the tank wall, which points towards the interior of the tank. Since gas is a very poor conductor of heat, the porosity of the material, its thermal conductivity can be significantly reduced compared to an identical solid material of the same thickness.

Additionally or alternatively, the principle of poor heat conduction of gases can also be realized in an application by at least one macroscopic gas-filled cavity. Again, one makes use of the poor heat transportability of gases advantage. However, unlike the porous material, the gas-filled cavity is not criss-crossed with a mesh of material that defines the individual pores with their volumes of gas. The gas-filled cavity thus contains a much larger amount of gas at the same volume as the porous material. It is formed by two in the thickness direction with spaced apart Teilwandungen, between which the gas is located.

Furthermore, in addition or alternatively, the thermal conductivity of the material of the tank wall or the heat transfer coefficient of the tank wall can be reduced by the use of filled plastic, namely the fact that the filler has a lower thermal conductivity than the plastic. Even such a material has, compared to an identical matrix plastic material of the same area and the same thickness, a lower thermal conductivity or a lower heat transfer coefficient.

In case of doubt, a plastic wall made of polyethylene with a thickness of 1.5 mm should be used as a comparison scale for the comparison tank wall without thermal insulation. To compare the thermal insulation properties of different materials, planar tiles made of the respective materials with edge lengths of 10 × 10 mm should be used as comparative samples. A tank wall with thermal insulation is usually thicker than the above-mentioned thermally non-insulated comparative tank wall.

The porous material can be used in different ways thermally insulating the reducing liquid tank. It may for example be formed from an open-celled foamed plastic, wherein then advantageously a liquid-impermeable barrier layer is provided, for example in the form of a film, wherein the film preferably has a thickness of less than 500 .mu.m, preferably less than 200 .mu.m, more preferably less than 100 microns to provide sufficient flexibility and light weight. By using a barrier layer in the form of a plastic film, the foamed plastic with barrier film can be used directly as a tank wall, so that a side facing away from the foamed plastic film side can form an inside of the tank wall. For facilitated connection of barrier layer and foamed plastic, the materials of the barrier film or barrier layer and of the foamed plastic are preferably compatible, particularly preferably identical. However, the open-cell foamed plastic as a thermal insulation material may also be arranged on the outside of a conventionally formed tank wall. A conventionally formed tank wall is a tank wall of solid plastic material, usually but not necessarily a polyolefin such as polyethylene, which has been blow molded or injection molded into the desired tank shape.

Alternatively or additionally, it is also possible to use a closed-cell foamed plastic as the porous material of the thermal insulation. In this case, a liquid-impermeable barrier layer can be dispensed with, since the closed-cell foamed plastic itself is liquid-impermeable.

Furthermore, additionally or alternatively, the porous material may comprise a thermoplastically bonded fiber material. As such fiber material is in particular a LWRT, so called a fiber-reinforced thermoplastic with low weight in question (LWRT = Low Weight Reinforced thermoplastic). Since these thermoplastically bonded fiber materials generally do not form closed pores, but are permeable to gas, the use of a liquid-impermeable barrier layer is advantageous here as well as in the above-discussed open-celled foamed plastic. For the liquid-impermeable barrier layer of the thermoplastic bonded fiber material, what has been stated above for the barrier layer of the open-celled foamed plastic applies correspondingly. The barrier layer, which in turn is in the form of a film, is preferably produced from a material which is compatible or identical to the thermoplastic binder material with which the fibers of the fiber material are bonded. Again, preferably a polyolefin is used, such as polypropylene or polyethylene. Again, in the absence of a barrier film, the thermoplastic bonded fiber material may be externally disposed on a conventionally formed tank.

The fiber material is usually a fiber tangle in which fibers are undirected and with stochastically distributed different fiber orientation. The fiber material may also be a non-woven fabric provided with a thermoplastic binder. However, the nonwoven need not be thermoplastic bound, it may also be solidified by needlepunching. When using a nonwoven as a fiber material - whether it is thermoplastic bound or thermoplastic unbound - again a liquid-impermeable barrier layer is advisable. This in turn may be a conventionally formed tank wall or may be compared with this thinner barrier film. If the nonwoven material is incompatible with the film material, the nonwoven may be adhered to the liquid impermeable barrier layer in the form of the film. The same applies to the attachment to the outside of a conventionally formed tank wall. The other porous materials can be glued to the outside of a conventionally formed tank wall or with a barrier film by gluing. As a result, even existing reduction liquid tanks can be retrofitted without thermal insulation with such.

Basically, the plastic used in the prior art for the production of Reduktionsflüssigkeitstanks already - compared to metals - low thermal conductivity. If you fill that in the However, usually thermoplastic material with filler, which has an even lower thermal conductivity than the plastic matrix itself, the thermal conductivity of the material thus obtained can be further reduced. The filling material for the filled plastic is glass or / and ceramic and / or stone in question. Preferably, small particles, if possible globular particles, are used as filling material. According to a preferred embodiment of the invention, the filler particles are hollow inside or filled with gas in order to set their thermal conductivity as low as possible. Hollow or filled with gas filler particles can be most easily reduced with globular particles, especially if the filler is formable, as is the case with glass, for example. Glass is preferred because of its material-inherent low thermal conductivity. A hollow interior can also be realized by a vacuole, that is by an evacuated space. In general, however, the cavity will be filled with gas.

In the case of stone, for example, stone meal can be used as filling material. The filled plastic formed in this way can be brought into the form of a tank with the usual shaping methods, as they are also used for the solid tank shells used hitherto, ie by blow molding or / and injection molding.

The at least one gas-filled cavity, which is a macroscopic cavity compared to the pores of the porous material to be regarded as microscopic cavities, can be formed by injection molding in injection molding, such as projectile injection technique, water injection technique or gas injection technique, in the tank wall itself. Then, the at least one gas-filled cavity, for example, be an elongated channel cavity, which is preferably at least once or more preferably angled several times to provide the largest possible surface of the tank wall with the cavity and thus to provide the largest possible thermally insulated tank wall surface.

Alternatively or additionally, the at least one gas-filled cavity can be realized by an at least partially double-walled design of the tank wall. For example, according to a preferred development of the present invention, the at least one gas-filled cavity can be formed by an additional wall component which has a wall surface extending parallel to the tank wall in the assembled state and spacer protruding from the wall surface toward the tank wall, wherein the auxiliary component by means of the spacer projections the tank wall is connected to form the gas-filled cavity. The spacer projections can thereby easily define the dimension of the cavity in the thickness direction of the tank wall.

As already described above, the thermal insulation can be applied to these in addition to an existing tank wall, usually on the outside of the tank wall. In order to save weight, however, the tank wall itself may be at least partially or even completely formed directly by the thermal insulation, as described above, itself, since this can be formed liquid-impermeable. An outer side of the thermal insulation then forms an inside of the tank wall and limits the interior of the tank directly.

As already known from the prior art, a heating device can be arranged locally in the tank interior on the tank wall or at a small distance of not more than a few millimeters from the tank wall in order to introduce heat into the tank interior with the heating device. In this case, it is advantageous if the tank wall has the thermal insulation where the heating device is arranged, while other areas of the tank wall may be formed without thermal insulation for reasons of low production costs and may have a higher heat transfer coefficient. Thus, heat discharged from the heater can be prevented from being lost through the tank wall to the outside environment of the reducing fluid tank. As also stated above, the thermal insulation, if it does not form the tank wall itself, at least in sections outside the tank interior to be arranged on a solid tank wall. The arrangement outside the tank interior is preferred in order to avoid full absorption of the thermal insulation, if this is porous, with reducing fluid.

In order to provide where the thermal insulation is provided on the reduction liquid tank, the same isolation conditions regardless of the considered location of the tank wall, is provided according to a preferred development that the thermal insulation touches the massive tank wall in a contact surface, wherein the thermal insulation substantially in the entire contact surface is permanently connected to the tank wall, for example by gluing or fusing.

The present invention will be explained below with reference to the accompanying drawings. It shows:

1 a rough schematic cross section through a first embodiment of a motor vehicle reduction fluid tanks according to the invention,

2 a rough schematic cross section through a second embodiment of a motor vehicle reduction liquid tank according to the invention,

3 a rough schematic cross section through a third embodiment of a motor vehicle reducing liquid tank according to the invention,

4 a rough schematic cross section through a fourth embodiment of a motor vehicle reduction liquid tank according to the invention,

5 a rough schematic cross section through a fifth embodiment of a motor vehicle reducing liquid tank according to the invention and

6 a bottom view of the tank bottom shell of the motor vehicle reduction liquid tank of the fifth embodiment of 5 ,

In 1 is an inventive motor vehicle reducing liquid tank (hereinafter referred to only as "liquid tank" or "tank") generally with 10 designated. The liquid tank 10 preferably comprises an upper shell part 12 that has a filling opening 14 with a filling opening 14 surrounding flange margin 16 having. At the flange edge 16 can be a filling line, about one in 1 Unillustrated filling tube to be connected.

The liquid tank 10 is an SCR tank which is designed and intended for receiving aqueous urea solution, which in turn is used in motor vehicles for the selective catalytic reduction of the exhaust gas and thus for exhaust gas purification. For this purpose available on the market aqueous urea solution is known under the trade name "AdBlue" ^® .

The liquid tank 10 further comprises a lower shell part 18 , which is a removal opening 20 with a removal opening 20 surrounding flange margin 22 having. Again, at the flange edge 22 one in 1 not shown sampling line to be connected.

The upper shell part 12 and the lower shell part 18 are preferably along a respective circumferential joining flange 24 respectively. 26 joined together, for example glued or welded. The joining flanges 24 and 26 touch each other along a joining surface 28 which is preferably flat.

The Tank 10 has a tank wall 30 on that a tank volume 32 in the tank interior 33 of the tank 10 surrounds. The tank wall 30 on the one hand is formed by the wall 34 of the upper shell part 12 and to the other is formed by the wall 36 of the lower shell part 18 ,

An inside 30a the tank wall 30 forms a boundary surface of the tank wall to the tank volume 32 out. The inside 30a is in turn formed on the one hand by the inside 34a the wall 34 of the upper shell part 12 and on the other hand is formed by the inside 36a the wall 36 of the lower part 18 ,

The liquid tank 10 may of course deviating from the example shown have more than two shell parts or may also be integrally formed, such as by blow molding.

In a floor section 38 of the tank 10 , more precisely, the lower shell part 18 , can be a heating device 40 on the tank volume 32 indicative inside 30a respectively. 36a to the tank volume 32 be arranged pointing. The heater 40 is preferably an electric heater. She can on the tank wall 30 , especially on the inside 30a be glued on.

The lower shell part 18 is - as well as the upper shell part 12 - Preferably produced by injection molding.

The shell parts 12 and 18 can each be produced in an injection mold in one step and then with their joining flanges 24 and 26 be joined together.

The heater 40 is shown only by way of example. It can span a larger or smaller area than the one in 1 shown on the tank bottom forming section 38 the inside 36a of the lower shell component 36 extend. Likewise, a heating device 40 on the side walls on the inside 36a of the lower shell component 36 or the upper shell component 34 be provided. There may also be no heating device 40 be provided.

The preferred reducing liquid in the form of aqueous urea solution freezes - depending on the blended additives - at temperatures of -11 ° C or colder. To delay unwanted freezing in the liquid tank 10 absorbed reduction liquid is the tank wall 30 of the liquid tank 10 the first embodiment preferably made of a thermally insulating material, wherein thermally insulating compared to a same thickness and equal shaped tank of solid plastic, such as PE or PP, is to be considered.

In 1 is the complete tank wall 30 ie both shell parts 12 and 18 made of glass-filled thermoplastic material by injection molding. The preferably globular filler particles of glass in the thermoplastic polymer matrix have a significantly lower thermal conductivity than the material of the thermoplastic polymer matrix itself, so that the tank wall thus produced 30 has a reduced heat conductivity or a reduced heat transfer coefficient relative to a tank wall produced the same thickness only from the thermoplastic material of the plastic matrix.

Alternatively to complete formation of the liquid tank 10 or its tank wall 30 made of filled thermoplastic material, wherein the filler particles are formed from a material with lower heat conduction than the thermoplastic resin matrix itself, can only sections of the tank 10 or the tank wall 30 be formed of such an insulating material.

In 2 is a second embodiment of a motor vehicle reduction liquid tank according to the invention with 110 designated. The same or functionally identical components and component sections as in the first embodiment are in 2 provided with the same reference numerals, but increased by the number 100.

The second embodiment of the liquid tank will be explained below only insofar as it differs from the first embodiment, the description of which is otherwise expressly referred to for explaining the second embodiment.

In the second embodiment of the liquid tank according to the invention 110 may additionally or alternatively to the thermally insulating formation of the tank wall 130 a thermal insulation by a gas-filled cavity 142 be formed. For this purpose, an additional wall component 144 forming the gas filled cavity 142 with the outside 130b the tank wall 130 be connected, for example by welding or gluing.

The additional wall component 144 may be roughly cupped pot-shaped, with a bottom portion 144a and with a protruding circumferential distance projection 144b , which together with a portion of the lower shell component 138 at which the additional wall component 144 with the free edge of the circumferential distance projection 144b is completely enclosed.

The filled cavity 142 is through two in the thickness direction of the tank wall 130 limited spaced apart walls limited, namely once through the bottom section 144a of additional wall component 144 and again through the area opposite this 138a of the bottom section 138 the tank wall 130 ,

In the example of 2 is the area below the heater 140 through the gas-filled cavity 142 additionally thermally insulated. Additionally or alternatively, other sections of the tank wall can also be used 130 be provided in a corresponding manner with a thermal insulation.

In 3 is a third embodiment of a motor vehicle reduction fluid tank according to the invention 210 of the present invention. The same or functionally identical components and component sections as in the previous two embodiments are provided with the same reference numerals, but increased by the number 100 or 200th

The third embodiment of 3 will be explained below only insofar as it differs from the preceding embodiments, the description of which is otherwise expressly referred to for explaining the third embodiment.

The third embodiment of 3 is the second embodiment of 2 similar. Again, a thermal insulation of the tank wall 230 through a macroscopic gas-filled cavity 242 reached. However, this is to form the gas filled cavity 244 used additional wall component 244 in contrast to the second embodiment of 2 not on the outside 230b the tank wall 230 arranged but on the inside 230a , In the present case is the additional wall component 244 on the inside 236a the wall 236 of the lower shell component 218 arranged. It covers there already during injection molding of the lower shell component 218 formed recess and closes this to a gas-filled cavity 242 from. The additional wall component 244 thus also forms a partial wall 244a which the cavity 242 in the thickness direction of the tank wall 230 limited.

Again in is 3 the gas filled cavity 242 shown as being local only in the area where the heating device is located 240 is arranged. Although this is preferred, this need not be so. Additionally or alternatively, other sections of the tank wall can also be used 230 with a gas filled cavity in the in 3 be shown thermally insulated.

In 4 a fourth embodiment of a motor vehicle reduction liquid tank according to the invention is shown. The same or functionally identical components and component sections as in the previous two embodiments are provided with the same reference numerals, but increased by the number 100 or 200 or 300 ,

The fourth embodiment of 4 will be explained below only insofar as it differs from the preceding embodiments, the description of which is otherwise expressly referred to for explaining the fourth embodiment.

In the fourth embodiment, as in 4 is shown, the thermal insulation is formed of porous material. The porous material may be a LWRT or may be a foamed material, such as a foamed plastic.

A merely for the sake of exemplification below the heater 340 illustrated thermal insulation 346 is made of open-pore porous material, such as open-cell plastic or LWRT. This thermal insulation 346 includes the open-pored material 348 leading to the tank interior 333 out with a liquid-impermeable film 350 is covered. The thermal insulation 346 forms part of the tank wall 330 and limited with its liquid-impermeable barrier film 350 the tank interior 333 immediate.

As in 4 is further shown, additionally or alternatively, porous insulating material outside the actual tank wall 330 be provided, for example, on the circumferential side walls of the lower shell component 318 , There is a porous material 352 which in turn may be formed from an open-cell or closed-cell foamed plastic or from a fiber-reinforced thermoplastic, in particular from a LWRT. Due to the arrangement of the porous material 352 on the outside 330b the tank wall 330 No barrier film is necessary, since already the tank wall 330 the insulation material 352 before a contact with the in the tank 310 Protected reducing fluid protects.

Then, if the thermal insulation 346 Made of closed-cell foamed plastic, the barrier foil can 350 even then omitted when the insulation 346 , as in 4 shown part of the tank wall 330 forms.

Also for the fourth embodiment of 4 is valid that deviating from the illustrated thermally insulated areas other tank wall sections may be additionally or alternatively isolated with a thermal insulation by porous material. It can also be the entire tank 310 from a porous material 348 with inner barrier film 350 be formed when the porous material 348 is sufficiently dimensionally stable. This is readily the case, for example, with a LWRT.

The in the 5 and 6 shown fifth embodiment, in turn, uses a gas-filled cavity 442 as thermal insulation. The same or functionally identical components and component sections as in the preceding embodiments are denoted by the same reference numerals as in FIGS 2 and 3 provided, but increased by the number 200 respectively. 300 ,

The fifth embodiment of 2 and 3 will be explained below only insofar as it differs from the preceding embodiments, the description of which is otherwise expressly referred to for explaining the fifth embodiment.

The gas filled cavity 442 the fifth embodiment of 5 is by gas or Projektilinjektionstechnik injection molding in the lower shell component 418 been formed. A bottom view of the floor section 438 in which the gas-filled cavity 442 is trained in is 6 shown. In 6 is the gas filled cavity 442 only shown by dashed lines, as he behind the actually visible outside 438b of the bottom section 438 the lower shell component is hidden.

The gas filled cavity 442 is as an elongated gas-filled cavity 442 with a meandering shape in the bottom section 438 of the lower shell component 418 designed to be from the cavity 442 Covered area of the tank wall 430 to enlarge. The openings of the gas-filled cavity produced during injection molding 442 can by stuffing 454 and 456 be closed to a defined amount of gas in the cavity 442 provide.

Again, it is true that other than the area of the bottom section shown 438 with a gas filled cavity 442 may be formed to a thermal insulation effect in the tank wall 430 to effect. Alternatively, it may also be thought of through the cavity 442 passing through a heating medium, at least in sections, in order to heat the tank interior. In this case, instead of the plug 454 and 456 Be provided line connection information for connection of a heating medium line.

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 102010004612 A1 [0002, 0005]
• EP 1473447 B1 [0003, 0005]

Claims (9)

Motor vehicle reducing liquid tank ( 10 ; 110 ; 210 ; 310 ; 410 ), which is designed in particular for the storage and removal of aqueous urea solution, with one of a tank wall ( 30 ; 130 ; 230 ; 330 ; 430 ) enclosed tank space under provision of a receiving volume ( 33 ; 133 ; 233 ; 333 ; 433 ), whereby the tank wall ( 30 ; 130 ; 230 ; 330 ; 430 ) a filling opening ( 14 ; 114 ; 214 ; 314 ; 414 ) for the introduction of reducing fluid into the tank interior ( 33 ; 133 ; 233 ; 333 ; 433 ) and an outlet opening for removal of reducing liquid from the interior of the tank ( 33 ; 133 ; 233 ; 333 ; 433 ), wherein the tank wall ( 30 ; 130 ; 230 ; 330 ; 430 ) at least in sections a thermal insulation ( 30 . 142 . 242 . 346 . 352 . 442 ), characterized in that the thermal insulation ( 346 ) is formed of porous material ( 352 ) and / or at least one gas-filled cavity ( 142 ; 242 ; 342 ; 442 ) between two in the thickness direction of the tank wall ( 30 ; 130 ; 230 ; 330 ; 430 ) spaced-apart part walls ( 138a . 144a ; 238a . 244a ; 438a . 444a ) and / or filled plastic, wherein the filler material has a lower thermal conductivity than the plastic. Motor vehicle reducing liquid tank ( 10 ; 110 ; 210 ; 310 ; 410 ) according to claim 1, characterized in that the porous material ( 348 . 352 ) an open-celled foamed plastic with a liquid-impermeable barrier layer ( 330 . 350 ) and / or a closed-cell foamed plastic or / and a thermoplastic bonded fiber material ( 348 ) with a liquid-impermeable barrier layer ( 330 . 350 ) and / or a nonwoven with a liquid-impermeable barrier layer ( 330 . 350 ). Motor vehicle reducing liquid tank ( 10 ; 110 ; 210 ; 310 ; 410 ) according to claim 1 or 2, characterized in that the filled plastic filler material made of glass and / or ceramic and / or stone, wherein the filler material preferably comprises globular particles, particularly preferably comprises hollow or gas-filled particles inside. Motor vehicle reducing liquid tank ( 10 ; 110 ; 210 ; 310 ; 410 ) according to one of the preceding claims, characterized in that the at least one gas-filled cavity ( 442 ) an elongated, at least once, preferably multiple angled channel cavity ( 442 ). Motor vehicle reducing liquid tank ( 10 ; 110 ; 210 ; 310 ; 410 ) according to one of the preceding claims, characterized in that the at least one gas-filled cavity ( 142 ; 242 ) is formed by an additional wall component ( 144 ; 244 ), which one in the mounted state parallel to the tank wall ( 130 ; 230 ) running wall surface ( 144a ) and at least one of the wall surface to the tank wall ( 130 ; 230 ) projecting distance projection ( 144b ), wherein the additional wall component ( 144 ; 244 ) by means of the at least one spacing projection ( 144b ) with the tank wall ( 130 ; 230 ) to form the gas-filled cavity ( 142 ; 242 ) connected is. Motor vehicle reducing liquid tank ( 10 ; 110 ; 210 ; 310 ; 410 ) according to one of the preceding claims, characterized in that the thermal insulation ( 242 . 346 . 442 ) at least in sections the tank wall ( 230 ; 330 ; 430 ). Motor vehicle reducing liquid tank ( 10 ; 110 ; 210 ; 310 ; 410 ) according to claim 6, characterized in that in the tank interior ( 33 ; 133 ; 233 ; 333 ; 433 ) locally heating ( 40 ; 140 ; 240 ; 340 ; 440 ) on the tank wall ( 30 ; 130 ; 230 ; 330 ; 430 ), wherein the tank wall ( 30 ; 130 ; 230 ; 330 ; 430 ) the thermal insulation ( 242 . 346 . 442 ) where the heating ( 40 ; 140 ; 240 ; 340 ; 440 ), while other areas of the tank wall ( 30 ; 130 ; 230 ; 330 ; 430 ) without thermal insulation ( 242 . 346 . 442 ) have a higher heat transfer coefficient. Motor vehicle reducing liquid tank ( 10 ; 110 ; 210 ; 310 ; 410 ) according to one of the preceding claims, characterized in that the thermal insulation ( 352 ) at least in sections outside the interior of the tank ( 333 ) on a massive tank wall ( 330 ) is arranged. Motor vehicle reducing liquid tank ( 10 ; 110 ; 210 ; 310 ; 410 ) according to claim 8, characterized in that the thermal insulation ( 352 ) the massive tank wall ( 330 ) in a contact surface, the thermal insulation ( 352 ) substantially in the entire contact surface with the tank wall ( 330 ) is permanently connected, for example by gluing or fusing.

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