DE102018200654A1 - Filter for a fluid medium - Google Patents

Abstract

The invention relates to a filter (10) for a fluid medium. The filter (10) has a housing (1) which encloses an interior space (11) with at least one inlet (4) or outlet (14) for the fluid medium, - a filter medium (2) for filtering Particles, wherein the filter medium (2) separates the interior space (11) from an external environment (12) of the filter (10); - an electric heating element (5) for heating fluid medium in the interior space (11). It is provided that the electrical heating element (5) in a wall (9) of the housing (1) is formed.

Description

Field of the invention

The invention relates to a filter for a fluid medium.

State of the art

The prior art filters for fluid media, e.g. Liquids or gases, known. These filters usually have a housing with a channel-like inlet or outlet for the fluid medium, and a filter medium which is adapted to e.g. To separate particles or dirt from the fluid medium. It may be necessary to heat the fluid in the filter. This can e.g. be necessary if the fluid medium is a liquid and the temperature causes the liquid to freeze (eg water or an aqueous urea solution for SCR use of a motor vehicle) or its viscosity increases too much (eg diesel fuel) ,

Heating elements for filters are known from the prior art, which are formed self-regulating, so-called PTC heating elements (PTC - positive temperature coefficient). They can be arranged in the interior of the filter and generate by applying an electrical voltage heat, which is delivered to the fluid medium.

From the DE 10 2009 055 084 A1 For example, a filter with such a PTC heating element is known.

Disclosure of the invention

The invention is based on the recognition that such PTC heating elements are present as separate components and must be placed in an additional work step in the interior and contacted, that they require space in the interior of the filter and only locally generate heat. Thus, it may take a relatively long time until the fluid medium in the entire interior is sufficiently heated in order to operate the filter efficiently.

There may therefore be a need to provide a filter for fluid media having an electrical heating element which requires only a small footprint, easy to manufacture and is electrically contactable and which emits the heat generated as large as possible to the fluid medium in the interior.

Advantages of the invention

This need can be met by the subject matter of the present invention according to the independent claim. Advantageous embodiments of the present invention are described in the dependent claims.

In the context of the application, the terms "comprise" and "comprise" are used synonymously unless expressly stated otherwise.

The fluid medium may be gases or liquids.

• -- ein Gehäuse, welches einen Innenraum umschließt, mit wenigstens einem Zulauf oder Ablauf für das fluide Medium;
• -- ein Filtermedium zur Filtrierung von Partikeln, wobei das Filtermedium den Innenraum von einer Außenumgebung des Filters trennt;
• -- ein elektrisches Heizelement zur Erwärmung von im Innenraum befindlichem fluidem Medium bzw. von Fluid.

According to a first aspect of the invention, a filter for a fluid medium is proposed. The filter has:

• - A housing which encloses an interior, with at least one inlet or outlet for the fluid medium;
• a filter medium for filtering particles, the filter medium separating the interior space from an external environment of the filter;
• - An electric heating element for heating befindlichem in the interior fluid medium or fluid.

In this case, the electrical heating element is formed in a wall of the housing.

This has the advantageous effect that the electrical heating element is easy to produce with the housing. The heating element may e.g. by means of an injection molding process (e.g., plastic injection molding). The heating element may e.g. at the same time casting molded in the housing, so that the heating element is integrated into the housing. For example, the heating element may be e.g. be injected in the wall of the housing. At the same time, the electrical heating element can be easily contacted in this way, since there is no need for electrical feedthroughs from the interior into an external environment of the filter, which would have to be laboriously sealed. Finally, by integrating the electrical heating element in the wall of the housing, the heat generated by the electric heating element can be emitted over a large area evenly to the fluid to be heated or the fluid medium

A wall of the housing may in this case be understood to mean any wall (for example outer wall, inner wall, side wall) of the housing and to form integrally formed or non-detachable (not without destruction) formations, e.g. in the form of a bulge, a rib, etc.

The housing may be formed, for example, box-shaped. It may, for example, have four or five walls or wall surfaces (eg four side surfaces and one bottom surface or only four side surfaces) and be open on one or two sides (eg at the top or both above and below). It may be covered with the filter medium, preferably at the open sides (eg at the top or both above and below). The housing and the filter medium can (almost) completely enclose an interior space. The interior is then accessible only through the filter medium and through the inlet or outlet. Inlet or outlet can be formed, for example, as relatively small openings in a wall of the housing. Inlet or outlet can be designed such that they do not make up more than 10% of the area surrounding the interior.

Characterized in that the electrical heating element is designed as a stamped grid, wherein the stamped grid is surrounded or overmolded by an electrically insulating plastic is a particularly simple and inexpensive production possible.

The stamped grid may e.g. act as an insert during an injection molding process or a dipping process. By such a configuration, advantageously, a large area of the wall of the housing can be heated simultaneously, whereby a particularly uniform and large-scale heat distribution is possible, which also protects the material of the housing: because so-called "hot spots" are avoided. Advantageously, this may e.g. frozen or gelled a frozen or gelled liquid (e.g., diesel fuel or aqueous urea solution) so that the filter is ready to use quickly even at very low temperatures (e.g., -25C or -40 ° C).

The electrical heating element may be formed as a metallic band or stamped grid with a partially different cross section. In this way, at points of reduced cross-section, in places (e.g., in desired heating zones), there may be increased electrical resistance, thus resulting in increased heat build-up during operation.

For electrical isolation from the fluid medium (e.g., a liquid, not necessary for gases), the electrical components may be sealed or overmolded. This can e.g. by injection molding, i. Encapsulation with non-conductive plastics happened. Alternatively or additionally, e.g. Dipping method, spray method, or similar used to apply an insulating layer around the electric heating element. It can e.g. Thermoplastics, paints or resins are used for the insulation layer. It is advantageous that the shape of the filter housing and the encapsulation or encapsulation of the electric heating element in a common process or by means of similar process steps can be effected. However, it is also possible to carry out the shaping of the filter housing and the casting or the encapsulation of the heating element in two process steps. This may be, for example, an injection process of a first housing element which surrounds the heating element only partially and a subsequent welding process of a further housing element with the injection-molded first housing element. By integrating the electrical heating element in the housing assembly steps and composite processes for the heating elements can be saved.

Characterized in that the electrical heating element is formed by an electrically conductive plastic, wherein the electrically conductive plastic has a specific electrical resistance of less than 100 ohm * cm, wherein the electrical heating element is surrounded or overmolded by an electrically insulating plastic is advantageously causes the electric heating element is particularly simple and inexpensive to produce and that the electric heating element can be easily produced even in the form of complex geometric shapes.

Electrically conductive plastics can be provided by adding electrically conductive particles to non-electrically conductive (ie insulating) plastics. Are sufficiently electrically conductive particles contained in the plastic, so a so-called percolation threshold is exceeded and the filled plastic reaches specific electrical resistances less than or equal to 100 ohm * cm. The plastics can be injection molded and contacted by thermal spraying (e.g., in accordance with DIN EN 657: 2005-06). By an electrically insulating component surrounding the electrically conductive plastic, the electrically conductive plastic can be isolated to the outside.

For electrical isolation from the fluid medium (eg a liquid, not absolutely necessary for gases), the electrical components can be tightly encapsulated or encapsulated. This can be done by injection molding, ie encapsulation with non-conductive plastics. Alternatively or additionally, for example, dipping method, spray method, or the like. used to apply an insulating layer around the electric heating element. It can, for example, thermoplastics, paints or resins are used for the insulation layer. It is advantageous that the shape of the filter housing and the encapsulation or encapsulation of the electric heating element in a common process or by means of similar process steps can be effected. It is, however possible to carry out the shaping of the filter housing and the encapsulation or the encapsulation of the heating element in two process steps. This may be, for example, an injection process of a first housing element which surrounds the heating element only partially and a subsequent welding process of a further housing element with the injection-molded first housing element. By integrating the electrical heating element in the housing assembly steps and composite processes for the heating elements can be saved.

The contacting may be e.g. by means of sprayed metallic powder (thermal spraying), wherein printed conductors are produced on the surface of the electrically conductive plastic, which feed the electric current into the electrically conductive plastic. The sprayed traces, in turn, can be contacted in a variety of ways, e.g. by clamping contacts, gluing with conductive adhesive, soldering, welding, etc.

The fact that the electrical heating element forms a web on a first wall of the housing, which protrudes into the interior advantageously further increases the heating surface. Preferably, such a web protrudes at least 2 mm, preferably at least 5 mm or at least 10 mm over a plane of an inner wall into the interior. Particularly preferably, the web projects at least along at least 25% of a distance between the inner wall, on which it is arranged, and an opposite inner wall. In this way, the heating surface is effectively increased. In this way, it is also possible with particular advantage to heat spots in the interior which are located farther away from the walls of the housing, ie in the direction of the center of the interior. At the same time, the flow or circulation of the fluid medium in the interior is impeded only insignificantly.

A web in the sense of this application is connected on one side to an inner wall and has on its other side a free end, which is bounded by an end face.

The web can e.g. protrude perpendicularly from a wall of the housing or be arranged at certain rotational and abutment angles on a wall of the housing. It can be flat or curved. The web cross section may have different embodiments, such as e.g. rectangular, round, oval, rhombic, etc.

Characterized in that the electrical heating element forms a plurality of webs on the first wall of the housing, wherein the webs protrude into the interior, a particularly large increase in the heating surface is effected. Since each web on its outer surfaces and on its front side, which limits its free end, comes into contact with the fluid medium, the fluid medium is heated uniformly and over a large area. In addition, the possibility of redundancy is created in case of failure of the electric heating element in a web, that is: the heating continues to work (in a parallel circuit of the webs).

A plurality of webs are to be understood as meaning two or more webs.

Characterized in that the electrical heating element is designed as a bridge element which connects a first wall of the housing with a second wall of the housing opposite the first wall, a particularly large heating surface is created. At the same time fluid medium, which is located in the middle of the interior can be heated by the electric heating element advantageous.

The bridge member may be configured to connect the first and second walls (e.g., two sidewalls), but spaced from a bottom or ceiling of the filter. Floor and / or ceiling can be e.g. be formed by the filter medium or through walls of the housing. In other words, the bridge element does not divide the interior into two separate and sealed internal spaces. In this way, it is ensured that the fluid medium can flow through the entire interior as unhindered as possible.

Characterized in that the second wall is substantially parallel to the first wall, the housing is particularly easy to manufacture and the heating power of the electric heating element is particularly uniform effect with a simple geometric shape, even when using a plurality of bridge elements. Because it is here only for a single bridge element, a simulation or a measurement of the heating distribution necessary to determine the heat output of the other bridge elements with the same design of the bridge element.

Characterized in that the electrical heating element is designed as a plurality of bridge elements which connect each of the first wall of the housing with the second wall of the housing is advantageously effected an even larger heating surface. As a result, the fluid medium can be heated more uniformly and faster to a target temperature. In addition, the possibility of redundancy is created in case of failure of the electric heating element in a bridge element, that is: the heating continues to work (in a parallel connection of the bridge elements).

Characterized in that the electrical heating element in the wall of the housing has an electrical plug contact, which faces the outer environment of the filter, the electric heating element can be contacted in a particularly simple. It is sufficient to put a complementary plug on the plug contact. The integration of the electrical plug-in contact in the wall of the housing, the filter can be particularly easily and inexpensively.

In this case, contacts or contact blades of the electrical plug contact protrude from the housing and then a complementary plug are attached to it. It can also be formed directly as a socket or a portion of the housing on which the complementary plug can be mounted. Such a socket can be designed such that the socket and plugged plug are sealed against the outside of the filter environment.

It can also be provided that a welding contour surround the contacts or contact blades leading out of the housing. By welding, the filter can be combined with other components of a fluid container, e.g. a tank in which the filter is arranged as part of a filter system, are tightly connected.

A further development provides that the filter is a liquid filter or that the filter is a fuel filter or that the filter is a diesel filter or that the filter is a filter for an aqueous urea solution. In all of these refinements, the proposed filter can heat the used fluid medium (here: liquid or fuel or diesel or aqueous urea solution) particularly quickly and uniformly to a target temperature.

drawings

Other features and advantages of the present invention will become apparent to those skilled in the art from the following description of exemplary embodiments, which are not to be construed as limiting the invention with reference to the accompanying drawings.

list of figures

• 1a : an external view of a filter;
• 1b-1d : Longitudinal sections through three different embodiments of the filter 1a ;
• 2a-2c : Longitudinal sections through three different embodiments of another filter;
• 3a an exterior view of another filter;
• 3b . 3c : two different longitudinal cuts through the filter 3a ;
• 3d : An equivalent circuit diagram for the electrical heating element of the filter from the 3a-3c ;
• 4a . 4b : Perspective views of another embodiment of a filter;
• 4c a perspective view of the electric heating element of the filter from the 4a . 4b with a representation of the heat distribution during operation.

• -- ein Gehäuse 1, welches einen Innenraum 11 umschließt, mit wenigstens einem Zulauf 4 oder Ablauf 14 für das fluide Medium;
• -- ein Filtermedium 2 zur Filtrierung von Partikeln, wobei das Filtermedium 2 den Innenraum 11 von einer Außenumgebung 12 des Filters 10 trennt;
• -- ein elektrisches Heizelement 5 zur Erwärmung von im Innenraum 11 befindlichem Fluid bzw. fluides Medium (siehe 1b bis 1d).

1a shows an external view of a filter 10 for a fluid medium, eg for a liquid, a fuel, diesel or an aqueous urea solution. The filter 10 may be provided for use in a motor vehicle. The filter 10 indicates:

• - a housing 1 which has an interior 11 encloses, with at least one inlet 4 or expiration 14 for the fluid medium;
• - a filter medium 2 for filtering particles, wherein the filter medium 2 the interior 11 from an outside environment 12 of the filter 10 separates;
• - An electric heating element 5 for heating in the interior 11 fluid or fluid (see 1b to 1d ).

The electric heating element 5 is in a wall 9 of the housing 1 trained (see 1b to 1d ).

In all figures, the flow direction of the fluid medium is from the outside space 12 in the interior 11 and from the filter 10 outlined by arrows.

At the inlet 4 or expiration 24 is a channel-like nozzle 25 arranged, through which the fluid medium through the inlet 4 through into the interior 11 can be directed or from the interior 11 through the process 24 can be led out through it.

Intake 4 or expiration 24 are present as an opening in a side wall, on an end face of a longitudinal axis of the housing 1 is arranged, formed. The housing 1 is presently designed as a rectangular box bounded on five of its six sides by walls and open on one side (here: the top). On the open side, the housing is through the filter medium 2 Completed, leaving liquid from the outside environment 12 only through the inlet 4 or through the filter medium 2 in the interior 11 can get.

It is understood that the case 1 or the filter 10 may also have a different shape than that of a rectangular box.

The housing 1 may be formed for example of a thermoplastic or thermosetting plastic. For example, the housing 1 Polypropylene, polyethylene or polyamide or consist thereof for the most part. The membrane may be formed, for example, as a plastic membrane or a filter fleece with a pore size of less than 20 microns, preferably less than 10 .mu.m.

The fluid medium occurs in the illustrated embodiment of the external environment 12 (here: raw side) through the filter medium 2 in the interior 11 (here: clean side) and leaves the interior 11 and with it the filter 10 through the opening in the wall of the housing 1 trained process 24 and the connected channel-like nozzle 25 ,

In the 1b to 1d are three longitudinal sections along the plane "AA" in 1a shown. Each of the 1b to 1d shows a different embodiment of the filter 10 ,

1b shows an embodiment in which the electric heating element 5 as a punched grid 15 , for example, stamped from a metal sheet, is formed. The punched grid 15 is in the wall 9 formed the first wall 18 the box-shaped housing 1 equivalent. The punched grid 15 can, for example, an electrically insulating plastic 16 be surrounded, for example, be encapsulated, so that the punched grid 15 does not come in direct contact with the fluid medium, but is isolated from it.

The punched grid 15 can through two out of the wall 9 in the outside environment 12 projecting electrical contact blades be electrically contacted, which has a plug contact 8th form. The plug contact 8th is through a contact socket 6 enclosed, leaving a complementary plug (not shown) close to the plug contact 8th can be plugged. In other words: the electric heating element 5 points in the wall 9 of the housing 1 an electrical plug contact 8th on, the outside environment 12 of the filter 10 is facing.

The electric heating element 5 in the form of the stamped grid 15 extends only along a portion which is about 25% of the extension length of the first wall 18 accounts.

1c shows a further embodiment of the filter 10 out 1a , In contrast to the embodiment of 1b extends the electric heating element 5 here essentially along the entire length of the first wall 18 in the wall 9 of the housing 1 , The electrical contact is made on two of the first wall 18 as a pin or contact blade led out electrical plug contacts 8th , which are each surrounded by a collar and so a contact socket 6 form.

1d shows a further embodiment of the filter 1a , In contrast to the embodiment of 1b forms the electric heating element 5 here a jetty 3 on the first wall 18 of the housing 1 out, with this jetty 3 in the interior 11 protrudes. The web preferably protrudes at least 2mm into the interior 11 in with respect to the plane of the first wall 18 , In the exemplary embodiment, the stag protrudes 3 about 50% of the distance between the first wall 18 and the parallel second wall 19 in the interior 11 into it. This can also be in the center of the interior 11 the fluid medium is heated evenly.

2a to 2c show longitudinal sections through three different embodiments of another filter 10 , With this filter 10 is the rectangular box-shaped housing 1 open on two sides and each of a filter medium 2 completed. The filter media 4 are here only by way of example along the longitudinal axis of the housing 1 located end faces of the housing (ie left / right in the figure).

2a shows a design of the electric heating element analogous to the training according to 1d , The electric heating element 5 is designed as a single bridge in the interior 11 protrudes. In this case, the electric heating element 5 through a punched grid 15 is formed and is of an insulating layer of the material of the housing 1 surround.

2 B shows an embodiment in which the electric heating element 5 in contrast to 2a a plurality of webs 3 on the first wall 18 of the housing 1 formed. In the present case is the electric heating element 5 in the wall 9 coming from the first wall 18 goes out, through three bars 3 trained in the interior 11 protrude.

2c shows an embodiment in which the electric heating element 5 in contrast to 2a as a plurality of bridge elements 7 is formed, which in each case the first wall 18 of the housing 1 with the second wall 19 of the housing 1 connect. In the present case is the electric heating element 5 in the wall 9 coming from the first wall 18 going out, by three bridge elements 7 trained in the interior 11 protrude. The electric heating element 5 is traversed here in the manner of a series connection of electric current. It is understood that embodiments may also be present in which the electric heating element 5 only as a single bridge element 7 is formed or by two or four or five or more bridge elements 7 is trained. A parallel connection is conceivable.

The second wall 19 runs essentially parallel to the first wall 18 , By "substantially parallel" is meant a course that deviates from the parallel direction by at most +/- 15 °.

The bridge elements 7 are of the bottom not shown in the longitudinal section and the ceiling of the housing 1 or from there optionally arranged filter media 2 spaced so that the fluid medium throughout the interior 11 can circulate.

3a shows an external view of another filter 10 , In this embodiment, the box-like, rectangular housing 1 perpendicular to the longitudinal axis (pointing in the figure from left to right), ie on the floor and on the ceiling, open sides, each through a filter medium 2 are covered. On its left side surface in the figure is a contact socket 6 arranged therein with electrical plug contact (not shown). The sequence 24 and the neck 25 are at the in the figure to the right-facing side wall of the housing 1 arranged.

3b shows a longitudinal section along the plane " AA " out 3a , The electric heating element 5 is here by an electrically conductive plastic 14 is formed, wherein the electrically conductive plastic 14 has a resistivity of less than 100 ohms * cm. The electric heating element 5 is for isolation of an electrically insulating plastic 16 surrounded, for example overmoulded.

Similar to in 2c is the electric heating element 5 as a plurality of bridge elements 7 formed, each of which is the first wall 18 of the housing 1 with the second wall 19 of the housing 1 connect. In the present case is the electric heating element 5 in the wall 9 coming from the first wall 18 goes out, through five bridge elements 7 trained in the interior 11 protrude. For this purpose, the two end faces (left and right), through which the longitudinal axis passes, are also electrical heating elements 5 educated.

The electrical contacting of the electric heating element 5 can be done for example via sprayed metallic powder (eg thermal spraying). This can be done on the first wall 18 and on the second wall 19 conductor tracks 17 are formed, which feed the electric current into the electrically conductive plastic. The electrical conductors 17 in turn can be contacted with contact blades or pins electrically, as an electrical plug contact 8th in the contact socket 6 sticking out of the case and the outside space 12 are facing. The electrical plug contact 8th or the contact blades or pins can be contacted in a variety of ways. For example, clamping contacts, gluing with conductive adhesive, soldering, welding, or attaching a complementary connector are conceivable. For example, the conductor tracks 17 geometrically formed (eg, by a large width or thickness perpendicular to the current flow direction) that they have only a low electrical resistance and are not strongly heated in this way. This may increase the risk of delamination from the walls 18 . 19 be reduced, even if the thermal expansion coefficient between the material of the walls 18 . 19 and the tracks 17 are clearly different. Because then there is not a big temperature difference between the walls 18 . 19 and the tracks 17 ,

The contact can alternatively or additionally, for example via conductive adhesive in the electrically conductive plastic 14 respectively. Cables or pins can be glued directly on. A pretreatment of the surface of the electrically conductive plastic 14 , For example, by a plasma, can be made to the adhesion of the tracks 17 to improve.

3c shows a further longitudinal section through the filter 3a , The cutting plane is in 3b indicated with "BB".

It can be seen that in the interior 11 arranged bridge elements 7 from the floor and ceiling of the interior 11 arranged filter media 2 are spaced. Furthermore, it can be seen that in the bridge elements 7 the electrically conductive plastic 14 from an insulating layer of non-electrically conductive plastic 16 is surrounded, so that in the interior 11 flowing fluid medium no direct access to the electrically conductive plastic 14 receives and so a risk of short circuit is minimized.

3d shows an equivalent circuit diagram for the electric heating element 5 of the filter 10 from the 3a to 3c , It can be seen that the electric heating element 5 is present in the manner of a parallel connection. In other words: every bridge element 7 is an independent heating element 5 , so that in case of damage (for example, no electrical line more) of a bridge element 7 the other bridge elements 7 work unchanged.

However, a series connection for the electric heating element is also off 3b imaginable.

The in the 1a to 2c shown punched grid heaters can also be implemented as a parallel circuit, although in the 1a to 2c a series connection has been shown.

4a shows a perspective view of another embodiment of a filter 10 , The housing 1 has two substantially parallel side walls, which are the first wall 18 and the second wall 19 form and are designed as circular ring segments. The first wall 18 and the second wall 19 are connected to each other at their distal ends by two further side walls, wherein on the left side wall in the figure, the drain 24 and the neck 25 are formed in the form of a channel. Floor and ceiling of the housing 1 are open and each with a filter medium 2 sealed fluid-tight in the sense that the fluid medium exclusively through the pores of the filter media 2 in the interior 11 can get. In the presentation of the 4a is for reasons of clarity, the electric heating element 5 been omitted (see 4b) ,

4b shows the filter 10 out 4a , but with the electric heating element 5 , where here now the process 24 and the neck 25 have been omitted.

In the left part of the 4b is the case again 1 to recognize. It can also be seen that the housing 1 with its wall 9 bridge elements 7 trains through the interior 11 pass through and the first wall 18 with the second wall 19 connect.

In the middle part of the 4b is the insulating layer of electrically non-conductive plastic 16 been omitted. It can be seen that the electric heating element 5 a coherent body of several bridge elements 7 forms, wherein the electric heating element 5 here made of electrically conductive plastic 14 is formed. The contacting of the electric heating element 5 is done by a conductor track 17 that in the first wall 18 and in the second wall 19 runs and on the electrically conductive plastic 14 of the electric heating element 5 is applied over a large area.

In the right part of the 4b is the course of the tracks 17 good to recognize, since here the bridge elements 7 have been omitted for the sake of clarity.

4c shows a perspective view of the electric heating element 5 of the filter 10 from the 4a . 4b with a representation of the heat distribution in operation - the temperature scale extends linearly between a minimum "Min" and a maximum "Max", intermediate steps being represented at ten intervals designated by the letters "A" to "J". The illustration shows an example of the temperature distribution for a minimum in the range between -25 ° C and -5 ° C and for a maximum in the range of + 60 ° C to + 80 ° C. In this case, an ambient temperature is about 5 ° C to 10 ° C colder than the minimum and the representation shows the temperature distribution in the equilibrium state some time after the start of the heating process.

It can be seen that the warmest zones (zones with the letter "A") in the middle of the bridge elements 7 lie and that to the edge of the bridge elements 7 (ie on the first and second wall 18 . 19 ) only a slight drop in temperature takes place. The coldest zones (zones with the letter "J") are located on the first and second walls 18 . 19 , It also follows that the interconnects 17 not or not significantly contribute to the heating and thus, for example, the risk of delamination of the tracks 17 from the walls 18 . 19 is minimized.

By forming a variety of bridge elements 7 which are essentially along the extent of the interior 11 Are arranged equidistant from each other, in the interior 11 fluid medium particularly fast, even and gentle on materials (also for the housing 1 and the filter medium 2 ) are heated. Hot spots are avoided.

The proposed filter is particularly well suited 10 for use in a tank filtration system of a motor vehicle for filtering an aqueous urea solution or diesel fuel. In this case, such a tank filtration system has a tank for liquid, as well as a filter arranged in the tank 10 , as described above.

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 102009055084 A1 [0004]

Claims (10)

Filter for a fluid medium, comprising: - A housing (1) which encloses an interior space (11), with at least one inlet (4) or outlet (14) for the fluid medium; - A filter medium (2) for filtering particles, wherein the filter medium (2) the inner space (11) from an outer environment (12) of the filter (10) separates; - An electric heating element (5) for heating in the interior (11) befindlichem fluid medium; wherein the electrical heating element (5) in a wall (9) of the housing (1) is formed. Filter after Claim 1 , wherein the electrical heating element (5) is formed as a stamped grid (15), wherein the stamped grid (15) by an electrically insulating plastic (16) is surrounded or encapsulated. Filter after Claim 1 , wherein the electrical heating element (5) by an electrically conductive plastic (14) is formed, wherein the electrically conductive plastic (14) has a specific electrical resistance of less than 100 ohm * cm, wherein the electrical heating element (5) of an electric insulating plastic (16) is surrounded or overmolded. Filter according to one of the preceding claims, wherein the electrical heating element (5) forms a web (3) on a first wall (18) of the housing (1), which projects into the interior space (11). Filter according to the preceding claim, wherein the electrical heating element (5) forms a plurality of webs (3) on the first wall (18) of the housing (1), wherein the webs (3) protrude into the interior space (11). Filter according to one of the preceding claims, wherein the electrical heating element (5) as a bridge element (7) is formed, which a first wall (18) of the housing (1) with one of the first wall (18) opposite the second wall (19) of the housing (1) connects. A filter according to the preceding claim, wherein the second wall (19) is substantially parallel to the first wall (18). Filter according to one of the two preceding claims, wherein the electrical heating element (5) as a plurality of bridge elements (7) is formed, each of the first wall (18) of the housing (1) with the second wall (19) of the housing (1 ) connect. Filter according to one of the preceding claims, wherein the electrical heating element (5) in the wall (9) of the housing (1) has an electrical plug contact (8) facing the outer environment (12) of the filter (10). Filter according to one of the preceding claims, wherein the filter (10) is a liquid filter or wherein the filter (10) is a fuel filter or wherein the filter (10) is a diesel filter or wherein the filter (10) is a filter (10) for an aqueous urea solution.

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