DE102009035272B4 - Heatable liquid container with adaptable heating element and method for its production - Google Patents

Abstract

Heatable liquid container (1) made of plastic material, in particular for holding mixtures of water urea, with a container interior (2) and a heating element (7) arranged substantially in the container interior (2) with at least two connection ends (9a, 9b), wherein the liquid container (1) an opening (8) through which extend the at least two terminal ends (9a, 9b) of the heating element (7), wherein the heating element (7) in the region of the terminal ends (9a, 9b) has a flange (11) or at one Flange (11) is fixed, and wherein the heating element (7) by means of the flange (11) releasably attached to the wall (4) of the liquid container (1), characterized in that the opening (8) and / or the heating element ( 7) are formed such that the heating element (7) can not be inserted or removed through the opening (8).

Description

The invention relates to a heatable liquid container made of plastic material, for. As thermoplastic materials such as polyethylene (PE), crosslinked polyethylene (XPE), polypropylene (PP), polyamide 6, 11 or 12 (PA 6, 11 or 12) or the like., In particular for receiving water urea mixtures, with a container interior and a substantially arranged in the container interior heating element with at least two terminal ends.

In order to meet the increasingly restrictive limitation of emission limits for internal combustion engines, especially in motor vehicles, there are various methods for exhaust aftertreatment. A particular problem here is the aftertreatment of diesel engine exhaust gases, since the engine operating conditions with lambda significantly greater than one do not permit simultaneous reductive and oxidative aftertreatment. To reduce the nitrogen oxides (NOx) contained in the exhaust gas therefore u. a. Catalysts used for a selective catalytic reduction (SCR) of nitrogen oxides. However, ammonia must be added as a further component for the reaction taking place on the catalyst.

In general, the ammonia is introduced by injecting a 32.5% aqueous urea solution from a storage tank in the vehicle. This urea solution is uniformly referred to by the industry as ^AdBlue® or in the USA as Diesel Exhaust Fluid (DEF) and is described in its composition in DIN 70070.

However, since the freezing point of this urea solution is about -11 ° C, there is a risk of freezing the solution in the tank of the vehicle depending on the season and region.

For this reason, generic liquid containers have a heating element which is arranged in the liquid container and avoids the freezing or volatilization of the urea preceding the complete freezing, as well as the thawing of the frozen urea solution during cold start.

From the GB 2 339 010 A a generic heatable plastic tank is known in which a heating coil is arranged in the interior, the Heizmittelein- and exits exit to the outside of the tank. The heating coil is designed to be freely supporting within the tank.

The GB 2 136 098 A discloses a heatable plastic tank with a heating coil made by a rotary melting process. The heating coil is completely cantilevered within the tank. The attachment of the heating coil inside the tank is done via connectors that are integrated into the side walls of the water tank. The heating coil disposed in the tank emerges from the tank in two places, where it is held in place by a clamp connection from the connectors in the form of plastic hoses. These are melted down in the manufacturing process in the side wall of the tank and have a projecting to the outside of the tank external thread, can be connected to the lines for supplying heat or Wärmemittelabfuhr. A disadvantage of such a construction, however, is that two areas to be sealed in the form of openings in the outer wall of the tank arise for supplying the heating coil. Such openings always bring the risk of leakage with it. In addition, the individual lines of the heating coil are arranged in direct contact with the plastic outer wall of the tank, with the result that heat-related material expansions, in particular the heating coil act on the plastic material of the tank and increase the fundamental risk of leakage. In addition, the heating coil is held by the connectors during the manufacturing process as they are fused into the sidewall. After the manufacturing process, it is no longer possible to move the heating coil, especially in the event of any maintenance work or in the context of necessary visual checks of the tank or the heating coil.

From the EP 1 640 577 B1 a heatable plastic tank is known in which Heizmitteleinlass and Heizmittelauslass a heating coil, which projects into the tank, are sintered in the lower tank area on the plastic tank wall of plastic. The heating coil is thereby immovably fixed in the tank. Again, there is a risk of leakage at the attachment points of the heating coil.

The EP 0 566 767 A1 describes a fuel heater for heating fuel at low temperatures with a heating element in the form of a heating chamber, which is vertically inserted into the fuel tank. In the chamber housing, inter alia, an electric tube heating element is arranged. By means of a flange, the heating chamber is fixed to the upper outer part of the fuel tank, wherein the electric pipe heating element is mounted in a central hole of the flange.

In the DE 10 2006 027 487 A1 describes a vehicle tank for a plastic urea solution, in which an inner container with an integrated electric heater is part of a separate functional unit. A pot on which a pump is mounted, as well as the inner container with the heater and a valve form the functional unit, the is independent of the tank and can be removed as a whole from the tank through an opening in the tank wall.

The from the DE 88 03 323 U1 known fuel tank provides at its upper portion an opening, which is dimensioned so that a heating coil can be inserted and removed again. The opening is closed after insertion of a seal by a metal lid.

It is therefore an object of the present invention to provide a equipped with a Temperierungssystem liquid container which is tight under all operating conditions and has a high efficiency in terms of heating power, the heating power is to ensure optimum temperature control of the liquid even in complex structures of the liquid container.

This object is essentially achieved in that the liquid container has a preferably round opening through which extend both terminal ends of the heating element. In the region of the connection ends, the heating element has a flange or is detachably attached to such a flange, this flange being fastened to the outside of the liquid container. Due to the fact that the liquid container has only one opening for passing through the two connection ends of the heating element, the number of openings required for the heating element is reduced by at least half in comparison with generic containers. Consequently, the risk of leakage is halved.

In addition, the heating element is not in direct contact with the wall of the liquid container because it is connected to the liquid container via the flange which is mounted on the outside of the liquid container. As a result, the heat conduction into the walls of the liquid container is minimized. There is only a heat transfer into the flange, which contributes to an improvement in the efficiency of the heating system of the liquid container. Furthermore, such decoupling of the heating element from the side wall of the container also avoids that material expansions of the heating element affect the tightness of the container or heat the tank wall such that sealing problems occur. Preferably, the entire heating element is cantilevered in the liquid container by the flange, so that the heating element is not in any position in direct contact with the liquid container or is supported in any way in the interior of the container. In general, however, it is also possible to support the heating coil on the tank by suitable means, such as feet or brackets, into or onto which the heating coil is lowered or inserted. It is within the scope of the invention that the heating coil, for example, is sprung supported by spring elements in the tank. Occurring voltages can be compensated.

This guarantees a complete flow around the heating element with the liquid to be tempered, which has a very efficient effect on the heating of the liquid. The attachment via the flange also brings with it the advantage that a container can be used with different specifications with regard to the connection to the heating element. Only the flange and the heating element are then adapted type-specific, but can basically be used in different containers. It should only be noted that the flange can be fastened to the container.

According to a further embodiment of the invention, the container may be made of a plastic material by means of a rotational fusion process. The container is thus made as a one-piece hollow body, which permanently and reliably prevents leaks occur on elements that have been assembled to seal the container. Due to the one-piece design, the tightness of the container is guaranteed for a long time. Similarly, the production by such a method allows a container with low tolerances and largely uniform wall thickness. In particular, with regard to the spatial design, this embodiment proves to be advantageous. It enables the integration of heat-efficient complex heating element structures in equally complex liquid container shapes. This brings with it considerable advantages, especially against the background of restrictive package requirements in vehicle construction. For effective utilization of the heat output is also provided that the heating element is not integrally connected to the container wall or is melted directly from the plastic.

Preferably, the heating element with the flange is releasably attached to the liquid container. In this way it is possible to move the heating coil in the liquid container and to make the interior of the liquid container for repairs or maintenance or even optical controls of the container or the heating element accessible.

A further embodiment of the invention provides that the opening and / or the heating element are formed such that the heating element can not be inserted or removed through the opening. In particular, in a liquid container, which is produced by means of a rotary melting process, the heating element is indeed disposed within the liquid container, but is characterized by the Flange attached to the outside of the liquid container. This means that even with complex structures of the liquid container and thus of the heating element only a small opening is necessary through which the terminal ends of the heating element protrude.

Ideally, the liquid container according to a further embodiment of the invention is designed such that it has means for fixing the flange. Such a fastening means can be, for example, a mounting flange already introduced or melted into the plastic during the manufacturing process. This in turn may comprise means for fixing the flange of the heating element, wherein preferably releasable fastening means, such as arranged around the opening around internal threads, are provided.

In a further development of this inventive concept, it is also possible to integrate such fastening means, such as, for example, internal threads or snap-in connections, into the tank wall during the production process. Such devices generally allow the uncomplicated and easy attachment of the heating element or the flange to the outer wall of the liquid container. Just as easy for maintenance or repair this connection can also be solved again, whereby the heating coil is easily accessible.

The invention further provides that the means for fastening the flange is designed as a connecting piece. The flange of the heating element can then be clamped against the nozzle or a sealing surface of the nozzle by means of a union nut, which can be fixed by threaded engagement or a latching connection to the means for fastening the flange. Preferably, at least one means for sealing is arranged between the flange and the outside of the liquid container. Such a means may for example be a sealing ring, wherein the seal avoids leakage of liquid from the liquid container.

Another embodiment of the invention provides for the arrangement of the heating element in the bottom region of the liquid container. The heat generally rising from the bottom area so warms the entire liquid in the liquid container in an effective manner. At the same time it is ensured that the liquid is reliably heated even when only partially filled container. Ideally, the heating element has a twisted shape such as a heating coil or a meandering heating coil, which increases the heat-emitting surface of the heating element and the heat input is improved in the liquid.

For introducing heat into the system, it may be provided that the heating element is designed as or contains an electrical conductor connected to a voltage source.

As a heating element can also be provided by a fluid flowing through the heating line. Advantageously, this fluid is the cooling water heated by an internal combustion engine or the heated reflux of the fuel. This provides a very simple and especially energy-saving way to supply fluid to the heating element when the liquid container is used in motor vehicles such as cars or trucks. Similarly, marine diesel engines can benefit from such a device.

It has proven to be advantageous if the flange has a filling / removal device for emptying or filling the liquid container. Such a device may, for. B. be an opening or a passage in the flange. As a result, can be dispensed with a further opening in the liquid container, in which the liquid would have to be introduced. Consequently, the risks of leakage are significantly reduced. At the same time, this offers a possibility for cost savings, since a separate filling / removal device is dispensed with.

In a further development of the invention, a further embodiment provides that the flange of the heating element has flow or return connections for the removal or return of the tank contents. Likewise, the integration of other functional elements, such. B. level sensor, temperature meter and quality sensors, a further advantageous use of this fastener, as costly and time-consuming additional work or installation work can be avoided on the container.

The invention further relates to a method for producing a liquid container according to the invention by means of rotary melting. In such a method, the heating element is attached via special mold inserts in a mounted on main and secondary axes of rotation rotary mold. Thereafter, the rotational mold is filled with a plastic material and set in rotation about main and secondary axes of rotation. Subsequently, heat is introduced into the rotational melt space. This can be done for example by an oven or a heat blower. Unlike conventional methods, however, the heating element is not firmly fused into the side walls of the liquid container. Instead, said special mold inserts may be surrounded by the plastic, but are ideally not firmly bonded to the plastic, but are releasable from the plastic after the melting process. After manufacture, the heating element is then loosely arranged in the liquid container and, after cooling, fixed by means of the flange on the outside of the liquid container.

Another advantageous method provides for the production of a liquid container which has two or more plastic layers. For such a method speak both strength and isolation reasons, but also a sufficient resistance of the container against the liquid to be absorbed. In this rotary melting process, in a first step, the heating element is fastened by means of special molding tools in a rotary tool mounted on the main and secondary axes of rotation. Subsequently, the rotary mold is filled with a first plastic material and set in rotation about the main and secondary axes of rotation. Subsequently, heat is introduced into the rotational melt mold, whereby a first layer of the first plastic material is formed. Subsequently, the rotary mold is again filled with the first or another plastic material, as in the previous step in rotation about the main and secondary axes of rotation and added heat. These steps are repeated for each additional layer. In this case, this method also provides in the individual melting stages that the heating element or a passage of the heating element is not firmly fused into the side walls of the liquid container.

By using different plastic materials, such as PE, foamed PE, XPE, PP, PA 6, 11 or 12, for the individual layers, the properties of the plastic container can be optimized, for example, in terms of robustness or resistance to various media.

The invention will be explained in more detail with reference to embodiments and the drawing. All described and / or illustrated features alone or in any combination form the subject matter of the invention, regardless of their combination in the claims or their dependency.

Show it:

1 a section through a liquid container according to a first embodiment of the invention,

2 a review of the liquid container 1 .

3 a front view of the liquid container 1 .

4 a fastening means introduced into a liquid container with means for fastening a flange according to a first embodiment of the invention,

5 an introduced into a liquid container fastening means with means for fixing a flange according to a further embodiment of the invention and

6 the attachment of the flange with a union nut according to a further embodiment of the invention.

The in 1 illustrated liquid container 1 has a container interior 2 on, through the side walls 3 , an upper container wall 4 and a lower container wall 5 is defined. In an oblique area of the one side wall 3 points the liquid container 1 a filling / removal opening 6 on, through the liquid in the container 1 introduced or can be removed from this. A heating element 7 is self-supporting in the container interior in the illustrated embodiment 2 arranged and serves to temper the in the liquid container 1 stored liquid. Alternatively, a support of the heating coil in the container interior 2 possible.

As 2 clarified, is in the upper tank wall 4 a preferably round opening 8th intended. The heating element 7 consists of a one-piece, spiral tube with two connection ends 9a and 9b that z. B. can serve as inlet and outlet of a Temperierungsfluides or as connections for an electric heating system. According to the invention, the connection ends 9a . 9b in a fluid-based temperature control suitable for connection to the cooling circuit of the internal combustion engine.

As 3 clarifies, are the terminal ends 9a . 9b outside the liquid container 1 , Starting from the outside connection ends 9a . 9b the main part of the heating element extends 7 through the opening 8th essentially parallel to the lateral walls 3 through the container interior 2 to the lower tank wall 5 (see. 1 and 2 ). In the lower part of the liquid container 1 the heating element extends 7 in a horizontal section 10 essentially parallel to the lower container wall 5 towards the side walls 3 in the form of a spiral heating coil. The spiral shape of the heating coil goes with an increase in the heat-emitting surface of the heating element 7 which additionally increases the efficiency of the tempering system. The arrangement of the tortuous section of the heating element 7 achieved due to the rise of the heated liquid high efficiency and is also almost always surrounded by medium to be tempered even at low level of the tank.

The wide horizontal section 10 the heating coil 7 However, that prevents the heating element 7 through the opening 8th introduce or remove is. The liquid container 1 is about the heating element 7 formed in a rotational fusion process, wherein the heating element 7 in the 2 loose and preferably non-contact in the liquid container 1 located.

In the area of the connection ends 9a . 9b indicates the heating element 7 an annular flange 11 outside the liquid container 1 which is fixed or detachable with the heating element 7 connected is. As in 1 shown is the flange 11 of the heating element above the opening 8th on the outside of the upper container wall 4 attached. In this way the flange closes 11 the opening 8th and protects against unwanted leakage of liquid from the liquid container 1 , The connection between flange 11 and liquid containers 1 can be done by means of non-detachable adhesive or welded connection or detachable connection, such as a screw or locking connection, wherein it is provided that, for example, one or more insertion elements with internal thread or locking device during the rotational fusion process around the opening 8th around in the wall 4 to get integrated. In this way, the flange 11 firmly to the liquid container 1 to be assembled. Alternatively, the attachment can also be carried out in plastic molded elements, such as blind holes for self-tapping screws or nozzles with external thread.

As the 1 and 2 illustrate, in the production by a rotary melting process, the heating element 7 and the flange 11 not with the plastic walls of the container 1 integrally connected or melted into the walls. The heating element 7 is thus at no point of the plastic of the liquid container 1 enclosed. According to the invention, the heating element 7 in the bottom area of the container interior 2 be supported by feet or brackets. The heating element is fastened 7 after the manufacturing process via the flange 11 on the outside of the liquid container 1 ,

Instead of the plastic walls of the liquid container 1 worn or supported on these, show the 1 and 2 the preferred embodiment that the heating element 7 as a result of this process and assembly by means of the flange 11 inside the liquid container 1 is arranged cantilevered and at any point in the container interior 2 is supported. In this way, the entire surface of the heating element is 7 in heat exchanging contact with the liquid to be tempered.

In addition, the indirect coupling of the heating element avoids 7 to the liquid container 1 unwanted leakage of liquid, because temperature-induced material expansions and distortions of the heating element can not act on the container walls.

Likewise, the attachment according to the invention via the flange 11 the heating element is able to compensate for material expansion and minimize heat conduction into the container walls, because the heating element 7 only indirectly with the upper container wall 4 over the flange 11 in contact.

Variable possibilities for fixing the flange 11 on the container show the 4 and 5 , In 4 are in the fastener 12 , which here is a mounting flange embedded in the plastic, several internal threads 13 placed around the opening 8th are arranged around. By means of the internal thread 13 can be the flange 11 on the liquid container 1 Fasten.

Alternatively, as in 5 is shown, locking elements 14 on the fastener 12 be provided. These are here in the opening 8th arranged where by simply latching the flange 11 on the fastener 12 can be attached. The locking elements 14 do not have to in the opening 8th be positioned. It is also possible to do this, similar to the internal threads 13 of the 4 to the opening 8th to arrange around.

A possible attachment of the flange 11 on the liquid container by means of a separate fastener shows 5 , Here is the fastener 12 formed such that it has an outwardly extending neck portion 15 which causes the opening 8th sleeve-shaped forms. The inflow and outflow 9a . 9b of the heating element 7 extend through the opening 8th , On this neck section 15 of the fastening element 12 is the flange 11 put on and by means of a union nut 16 on the outer side of the neck section 15 via a thread with the fastener 12 is screwed against the fastener 12 braced. Instead of a thread, the union nut can also be fixed by means of a quick release locking connection to the fastener. In addition, there is between the flange 11 and the fastener 12 a sealing ring 17 provided, which avoids unwanted leakage of liquid.

LIST OF REFERENCE NUMBERS

1

liquid container

2

Container interior

3

lateral walls

4

upper tank wall

5

under container wall

6

Fill / removal opening

7

heating element

8th

opening

9a, 9b

Connecting inlet / outlet

10

horizontal section

11

Flange of the heating element

12

fastener

13

inner thread

14

locking connection

15

Neck of the fastener

16

Nut

17

poetry

Claims (20)

Heatable liquid container ( 1 ) made of plastic material, in particular for receiving mixtures of water urea, with a container interior ( 2 ) and a substantially in the container interior ( 2 ) arranged heating element ( 7 ) with at least two connection ends ( 9a . 9b ), wherein the liquid container ( 1 ) an opening ( 8th ), through which the at least two terminal ends ( 9a . 9b ) of the heating element ( 7 ), wherein the heating element ( 7 ) in the area of the terminal ends ( 9a . 9b ) a flange ( 11 ) or on a flange ( 11 ), and wherein the heating element ( 7 ) by means of the flange ( 11 ) detachable on the wall ( 4 ) of the liquid container ( 1 ), characterized in that the opening ( 8th ) and / or the heating element ( 7 ) are formed such that the heating element ( 7 ) not through the opening ( 8th ) is insertable or removable. Liquid container according to claim 1, characterized in that the liquid container ( 1 ) is produced by means of a rotational fusion process. Liquid container according to claim 1 or 2, characterized in that the liquid container ( 1 ) Means for fixing the flange ( 11 ) having. Liquid container according to claim 3, characterized in that the means is an inserted into the plastic mounting flange, the means for releasably attaching the flange in particular ( 11 ) of the heating element ( 7 ) having. A liquid container according to claim 3, characterized in that the means in the plastic introduced fasteners, such. B. internal thread or snap-in connections, for particular releasable attachment of the flange ( 11 ) of the heating element ( 7 ) are. A liquid container according to claim 3, characterized in that the means for fixing neck-shaped, z. B. in the form of a nozzle, is formed and an external or internal thread or a locking connection for attachment of a union nut or the like. Has. Liquid container according to one of the preceding claims, characterized in that between the flange ( 11 ) and the liquid container ( 1 ) at least one means for sealing, such. B. a sealing ring is arranged Liquid container according to one of the preceding claims, characterized in that the heating element ( 7 ) is arranged in the bottom region of the liquid container. Liquid container according to one of the preceding claims, characterized in that the heating element ( 7 ) has a tortuous shape. Liquid container according to one of the preceding claims, characterized in that the heating element ( 7 ) is an electrical heating element. Liquid container according to one of claims 1 to 8, characterized in that the heating element ( 7 ) is a heating line through which a fluid flows. Liquid container according to one of the preceding claims, characterized in that the flange ( 11 ) a filling / removal device, such. B. a passage for emptying or filling the liquid container ( 1 ) having. Liquid container according to one of the preceding claims, characterized in that the flange ( 11 ) Has supply and / or return connections for removal or return of the tank contents. Liquid container according to one of the preceding claims, characterized in that the flange further functional elements, such as level sensor, temperature meter or quality sensors. Liquid container according to one of the preceding claims, characterized in that the heating element ( 7 ) inside the liquid container ( 1 ) is supported for example by feet or brackets. Liquid container according to claim 15, characterized in that the heating element ( 7 ) is resiliently supported. Process for producing a liquid container according to one of the preceding claims in a rotary melting process, in which a) the heating element ( 7 ) is attached via special mold inserts in a mounted on main and secondary axes of rotation rotary mold; b) the rotational melt mold is filled with a plastic material; c) the rotational melt mold is set in rotation about the main and secondary rotational axes; d) heat is introduced into the rotary melt mold; wherein the heating element or a passage of the heating element is not firmly sealed in walls of the liquid container. The method of claim 17, wherein the steps b) to d) are repeated, if necessary several times. The method of claim 18, wherein at least two different plastic materials are used with respect to the individual repetitions. Method according to one of claims 17 to 19, wherein the heating element ( 7 ) after rotational melting on an outer wall of the liquid container ( 1 ) is attached.

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