Operating fluid tank

Abstract

An operating fluid tank for a motor vehicle, in particular for storing an aqueous additive, comprising: a tank wall made of a thermoplastic material, wherein the tank wall has a top, a bottom and side walls, and the tank wall delimits a tank volume, wherein the tank volume has a height, a depth and a width; and at least one electrically operated heating device having one or more heating elements, the heating element being inserted into an outer depression of the tank wall, or into an outer recess or opening in the tank wall, or into an inner structure that is integrally formed with the tank wall and that extends into the tank volume, and said heating element extending over at least one third of the height of the tank volume and being electrically contacted outside the tank volume.

Claims

1. An operating fluid tank for a motor vehicle, in particular for storing an aqueous additive, comprising: a tank wall made of thermoplastic material, wherein the tank wall comprises a top, a bottom and side walls, the tank wall delimits a tank volume, wherein the tank volume has a height, a depth and a width, with at least one electrically operated heating device which comprises at least one heating body, wherein the heating body is inserted in an outer depression of the tank wall or in an outer recess of the tank wall or in an inner structure of the tank wall and extending into the tank volume, wherein the tank wall has an inner side which faces the tank volume and an outer side which defines the outer depression, the outer recess or the inner structure, wherein the heating body is disposed at the outer side of the tank wall with the tank wall disposed between the heating body and the aqueous additive when stored in the tank volume, wherein the heating body extends over at least one third of the height of the tank volume and is electrically contacted outside of the tank volume.

2. The operating fluid tank as claimed in claim 1, wherein the heating body is arranged with respect to the tank volume such that it is not in direct contact with a medium located within the tank volume.

3. The operating fluid tank as claimed in claim 1, wherein the heating body is inserted from the outside in a depression, a recess or an opening in the bottom of the tank wall.

4. The operating fluid tank as claimed in claim 1, wherein the tank wall has at least one pocket which is accessible from the outside and, within the tank volume, forms at least one wall extending over at least one third of the height of the tank volume, and in that the pocket accommodates at least one heating body inserted from the outside.

5. The operating fluid tank as claimed in claim 1, wherein the heating body is inserted from the outside in a stiffening element extending between the bottom wall and the top wall within the tank volume.

6. The operating fluid tank as claimed in claim 1, wherein the heating body is formed as a plastic-sheathed heating cartridge which passes through the bottom of the tank wall and extends into the tank volume, and is welded to the tank wall.

7. The operating fluid tank as claimed in claim 1, wherein the heating body is formed as a resistance heating element.

8. The operating fluid tank as claimed in claim 1, wherein the heating body is formed as a metal heat-conductive element which is in thermally conductive contact with at least one resistance heating element.

9. The operating fluid tank as claimed in claim 8, wherein the metal heat-conductive element is sheathed and/or encapsulated with thermoplastic material.

10. The operating fluid tank as claimed in claim 9, wherein the metal heat-conductive element is enclosed by the thermoplastic material of the tank wall.

11. The operating fluid tank as claimed in claim 1, wherein the resistance heating element is selected from a group of heating elements comprising polymer-bonded resistance heating elements, PTC polymers (PPTC), pasty or gel-like PTC polymers, ceramic PTC and plastic-encased or plastic-encapsulated or plastic-sheathed ceramic PTC.

12. The operating fluid tank as claimed in claim 1, wherein the inner structure of the tank wall and extending into the tank volume comprises a baffle wall.

13. The operating fluid tank as claimed in claim 1, wherein the inner structure of the tank wall and extending into the tank volume comprises a stiffening element which is connected to the top wall and the bottom wall.

14. The operating fluid tank as claimed in claim 1, wherein the tank wall has the outer depression, and the heating body is inserted in the outer depression of the tank wall.

15. The operating fluid tank as claimed in claim 1, wherein the tank wall has the outer recess, and the heating body is inserted in the outer recess of the tank wall.

16. The operating fluid tank as claimed in claim 1, wherein the tank wall has the inner structure extending into the tank volume, and the heating body is inserted in the inner structure extending into the tank volume.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention is explained hereinbelow on the basis of a plurality of exemplary embodiments shown in the drawings, in which:

(2) FIG. 1 shows a first exemplary embodiment of the operating fluid tank according to the invention which has heated structures within the tank volume;

(3) FIG. 2 shows a second exemplary embodiment of the operating fluid tank according to the invention with heated structures extending in a continuous manner between the top and the bottom;

(4) FIG. 3 shows a third exemplary embodiment of the operating fluid tank according to the invention with pockets integrated into the tank wall, in which heating bodies are inserted from the outside;

(5) FIGS. 4a and 4b show a fourth exemplary embodiment of the operating fluid tank according to the invention with a heating cartridge passing through the tank wall and extending into the tank volume;

(6) FIG. 5 shows a fifth exemplary embodiment of the operating fluid tank according to the invention; and

(7) FIG. 6 shows a sixth exemplary embodiment of the operating fluid tank according to the invention with an encapsulated heat-conductive element.

DETAILED DESCRIPTION

(8) The operating fluid tank 1 according to the invention is shown in a greatly simplified manner in the drawings. The operating fluid tank 1 comprises at least one filling opening and at least one removal opening as well as what is termed a delivery module (these not being shown in the drawings). By way of example, the delivery module may comprise a pump, a filling level sensor, a quality sensor etc. The delivery module is, for example, connected to a metering device which may comprise a feed line to an injection nozzle in the exhaust-gas tract of a passenger car and a return line into the operating fluid tank 1. If the operating fluid tank is provided as a water container for water injection into the internal combustion engine of a passenger car, a removal line provided in or on the operating fluid tank 1 is connected to the feed line of one or more water injection nozzles.

(9) In the described exemplary embodiment according to FIG. 1, the operating fluid tank 1 may, for example, be composed of two injection-molded half-shells made of thermoplastic material, preferably of HDPE. The operating fluid tank 1 comprises a tank wall 2 which has a top 3 and a bottom 4 as well as side walls 5. The tank wall 2 encloses a tank volume 6.

(10) In the exemplary embodiment according to FIG. 1, heated structures are provided within the tank volume 6, are integrally formed with the tank wall 2 and extend into the tank volume 6. These heated structures may be formed, for example, as baffle walls 7 or stiffening elements 8. The baffle walls 7 extend within the tank volume 6 over a height which is greater than approximately one third of the height of the tank volume or the distance between the top 3 and the bottom 4. The heated structures each enclose a heating body 9 which is not directly in contact with the medium stored within the tank volume 6. The heating bodies 9 may be, for example, ceramic heating bodies with a positive temperature coefficient. As an alternative, the above-mentioned heating polymers are suitable as heating bodies 9. These heating bodies 9 are electrically contacted outside of the tank volume 6 and connected to a voltage source (not shown).

(11) FIG. 2 shows a second exemplary embodiment of the operating fluid tank 1 according to the invention.

(12) In all exemplary embodiments, the same components are provided with the same reference signs.

(13) The operating fluid tank 1 according to the second exemplary embodiment may similarly be composed of two injection-molded half-shells. The top 3 and the bottom 4 of the tank wall 2 are connected to one another via the stiffening element 8. The stiffening element 8 is formed by two column-shaped depressions in the top 3 and the bottom 4 of the tank wall, said depressions being arranged oppositely and the end faces of which are welded to one another. In the drawing, only one stiffening element 8 is shown, but the invention is to be understood such that the operating fluid tank 1 may have a multiplicity of stiffening elements 8 of this type. A heating body 8 is inserted in each of the column-shaped depressions so that a continuously heated column or support is formed between the top 3 and the bottom 4 of the operating fluid tank 1. In this way, a uniform input of heat into the tank volume 6 is achieved over the entire height of the stiffening element 8 or over the entire height of the tank volume 6 into the medium.

(14) A third exemplary embodiment of the operating fluid tank 1 according to the invention is shown in FIG. 3. One or more pockets 10 are provided in the tank wall 2 of the operating fluid tank 1, each pocket 10 accommodating a heating body 9. In FIG. 3, only one pocket 10 is provided in the bottom 4 of the tank wall 2, however in principle a plurality of pockets may be provided in the tank wall 1 at various locations on the tank wall 1, that is to say both in the bottom 4 and in the top 3 and in the side walls 5. The pockets 10 are formed such that they protrude into the tank volume 6 and dip as far as possible into the fluid or into the medium. Blade-shaped molded heating bodies 9 in the form of ceramic heating elements or in the form of polymer-bonded heating elements may be inserted in the pockets 10. As already explained above, the heating elements are preferably formed as resistance heating elements with a positive temperature coefficient.

(15) The arrangement of the heating bodies 9 in the pockets 10 allows for relatively easy electrical contacting from the outside, for example as shown, on the bottom side of the operating fluid tank. In order to improve the transfer of heat from the heating body 9 to the medium located in the tank volume 6 via the tank wall 2, it may be provided that a heating paste is provided between the heating body 9 and the tank wall 2 in the pocket 10. A connection cable 17 to a voltage source (not shown) is shown only by way of indication.

(16) A fourth exemplary embodiment of the operating fluid tank 1 according to the invention is shown in FIGS. 4a and 4b. At least one opening 11 is provided in the tank wall 2 of the operating fluid tank 1, in which opening a heating cartridge 12 is inserted. The heating cartridge 12 comprises a heating body 9 as a resistance heating element which is encapsulated with a plastic sheath. The resistance heating element, like the above-described heating bodies 9, may be a ceramic PTC heating element, a PTC polymer or another plastic-bonded resistance heating element that has a positive temperature coefficient.

(17) The heating cartridge 12 comprises an integrally molded-on or formed-on collar 13 made of thermoplastic material and preferably arranged at an end of the heating cartridge 12. The thermoplastic material of the sheath of the heating cartridge 12 and of the collar 13 is expediently compatible with the thermoplastic material of the tank wall 2 for the purposes of weldability. The heating cartridge 12 may be formed as a cylindrical or else plate-shaped element. Accordingly, the opening 11 may be of circular or slot-shaped form. The heating cartridge 12 is inserted in the opening 11 of the tank wall 2, the collar 13 being welded on its outer side to the tank wall 2 and sealing the opening 11. The heating cartridge 12 is electrically contacted outside of the tank volume 6 via the connection cable 17.

(18) As an alternative, the heating cartridge 12 may be sealed in the opening 11 by means of one or more sealing elements (O-rings). In this case, welding is not necessary.

(19) The invention is to be understood such that one or more heating cartridges 12 may be provided, each passing through the tank wall 2 at various locations and protruding relatively far into the tank volume 6, in order thus to achieve a possibly uniform transfer of heat into the medium.

(20) A further variant of the operating fluid tank 1 according to the invention is shown in FIG. 5. The heating body 9, which extends substantially within the tank volume 6, is integrally formed with the tank wall 2 and electrically contacted from the outside. The heating body 9 may, for example, be formed as a cylindrical or plate-shaped body which has been encapsulated with a thin HDPE layer with a thickness of approximately 1 to 2 mm. The heating element finished in this way may for example have been placed into the mold during the injection molding of a shell of the tank wall 2 so that the tank wall 2 is integrally connected to the heating body. As is the case in the other exemplary embodiments, by way of example only one heating body 9 is shown, connected to the bottom 4 of the tank wall 2. The invention is to be understood such that a plurality of heating bodies 9 may be provided at various locations on the tank wall. As concerns the configuration of the heating body 9, the heating body is preferably a resistance heating element with a positive temperature coefficient, as is described in conjunction with the above-described exemplary embodiments.

(21) A further exemplary embodiment of the operating fluid tank 1 according to the invention is shown in FIG. 6. FIG. 6 shows an enlarged section of the tank wall 2 in the region of the bottom 4. A metal heat-conductive element 14 is inserted in the tank wall 2 and encompassed in a form-fitting manner by the tank wall 2. The heat-conductive element 14 may, for example, be provided with a multiplicity of ribs 15 which are enclosed by the thermoplastic material of the tank wall 2 and form the plate-shaped or rib-shaped structures which protrude into the tank volume 6 of the operating fluid tank 1 but are not in direct contact with the medium stored in the tank volume 6. In the drawing, the metal heat-conductive element 14 comprises only a single rib 15. The heat-conductive element 14 may be formed in the manner of a heat exchanger body with an enlarged surface area. The heat-conductive element 14 may, for example, be formed from aluminum and may have been integrated into the tank wall by injection molding during the production of the operating fluid tank 1.

(22) By way of example, the operating fluid tank 1 may also have been produced by extrusion blow molding or deep drawing. In this case, the heat-conductive element 14 may have been placed into the mold as an insert part. The heat-conductive element 14 is directly connected to a heating body 9. The heating body 9 is, for example, adhesively bonded onto the outer side and bottom side of the heat-conductive element 14 and covered with an insulating structure 16. The heating body 9 may be formed as a resistance heating element (PTC) made of the above-mentioned materials.

LIST OF REFERENCE SIGNS

(23) 1 Operating fluid tank 2 Tank wall 3 Top 4 Bottom 5 Side walls 6 Tank volume 7 Baffle walls 8 Stiffening element 9 Heating body 10 Pocket 11 Opening in the tank wall 2 12 Heating cartridge 13 Collar 14 Heat-conductive element 15 Rib 16 Insulating structure 17 Connection cable