Filter device for fluids, especially for fuels

Abstract

A filter device for fluids comprises a filter element arranged in a filter housing and a heating device arranged in the flow path of the fluid. The heating device comprises a heating element mounted on a heating support arranged on the inside of the cover. A water outlet nozzle is formed integrally with the heating support and leads to the outside through a recess in the cover.

Description

Technical area

[0001] The invention relates to a filter device for fluids, in particular for fuels in an internal combustion engine, according to the preamble of claim 1. State of the art

[0002] DE 10 2006 034 077 A1 describes a liquid filter equipped with a heater for heating the medium flowing through the filter device. The heater is designed as an electrically heatable heating track that is injected into the filter housing. The heating track is integrated into the wall of the pot-shaped filter housing and surrounds the filter element in a ring on its outer side, which represents the untreated side, so that the fluid reaching the untreated side is heated by the heating track.

[0003] EP 0 162 939 A1 discloses a heating device for diesel fuel in an internal combustion engine. The heating elements are PTC elements arranged on the front side of the housing. The PTC elements are located on a cover of the housing, through which the inflow and outflow of diesel fuel also occur. The cover, which can be placed on the front side of the pot-shaped housing, has a flow space between an outer and an inner cover shell for flow guidance, with the PTC elements being arranged on the side of the inner housing shell facing the housing pot. DE 10 2007 010 503 A1 discloses a component for a liquid filter, in particular a fuel filter, which contains a heating device for heating a liquid, a detection device (16) for detecting a level of a further liquid, in particular located in a reservoir, and a drainage channel for the further liquid.The component is a one-piece component in which the heating device, the detection device and the drainage channel are formed.

[0004] The invention is based on the object of designing a filter device for fluids with a compact construction using simple structural measures in such a way that rapid heating of the fluid is ensured with simplified assembly and maintenance. Disclosure of the invention

[0005] This object is achieved according to the invention with the features of claim 1. The subclaims specify expedient further developments.

[0006] The filter device according to the invention can generally be used for the filtration of fluids, in particular liquids, although use for gaseous fluids is also conceivable. In a preferred embodiment, the filter device is used for the filtration of fuels in internal combustion engines. In particular, the filter device is suitable for heating and filtering diesel fuel.

[0007] The filter device comprises a filter element in a filter housing through which the fluid flows. To heat the fluid before filtration, a heating device is arranged upstream of the filter element in the fluid flow path, through which heat is introduced into the fluid. The heating device is located on the inside of a cover that closes the preferably pot-shaped filter housing.

[0008] The heating device comprises a heating element mounted on a heating support located on the inside of the lid. A water outlet connection is formed integrally with the heating support and communicates with a drainage channel in the filter housing. The drainage channel is connected to the heating support. The water outlet connection leads to the outside through a recess in the lid.

[0009] In this design, the heating support performs additional functions. Firstly, the heating support houses not only the heating element but also the drainage channel through which separated water can be drained from the filter device. Secondly, the water outlet connection is formed as a single piece with the heating support and is fluidly connected to the drainage channel. The one-piece design of the water outlet connection and heating support results in a compact, small-sized component. The heating support can be inserted into the pot-shaped filter housing as a prefabricated module, which also includes the drainage channel. The cover is then fitted on top so that the water outlet connection protrudes through the recess in the cover.In this way, the heating support, including the components held on it - heating element, water outlet nozzle and drainage channel - can be easily inserted into the filter housing as a prefabricated module, whereby the heating support is also securely fixed when the cover is put on.

[0010] According to a further advantageous embodiment, electrical contact pins are connected to the heater support and a water level sensor and are guided through a recess in the cover. The contact pins serve in particular for the electrical connection of a water level sensor installed in the filter device, which is used to measure the level of separated water in the filter housing. The water level sensor is preferably located in or on the drainage channel. The heater support therefore has the additional function of accommodating both the contact pins and – via the drainage channel – the water level sensor. The heater support thus supports the water outlet nozzle, the drainage channel, the electrical contact pins, and the water level sensor. This module is installed in the filter housing during assembly and secured in the desired position by closing the cover in the filter housing.To compensate for component and manufacturing tolerances, a spring element is arranged between the filter element and the filter housing base, ensuring a positive fit between the module and the cover. At the same time, the electrical connection to the contact pins and the flow connection to the water outlet nozzle can be easily established by replacing the cover.

[0011] According to a further advantageous embodiment, a fluid inlet nozzle and a fluid outlet nozzle are also connected to the heating support and guided through recesses in the cover. The fluid to be cleaned or the already cleaned fluid is introduced into the filter device and discharged from it via the fluid inlet and outlet nozzles. Thus, a total of several recesses are incorporated into the cover, through which the water outlet nozzle, the contact pins, the fluid inlet nozzle, and the fluid outlet nozzle protrude. In this way, all connections are made via the front side of the filter device in the area of ​​the cover. No further connections are required.

[0012] Furthermore, it is advisable to form sealing lips on the drainage channel and, if necessary, also on the outlet nozzle, which ensure a tight seal with adjacent components. In the case of the drainage channel, this creates a seal with a central pipe supporting the filter element; in the case of the outlet nozzle, this creates a seal with the heating support and / or a component connected to the drainage channel. This eliminates the need for additional sealing elements on the drainage channel and the outlet nozzle.

[0013] The heater support is preferably designed as a single plastic part, as are the components formed integrally with the heater support, such as the water outlet nozzle. The drainage channel is also advantageously designed as a plastic part.

[0014] According to the invention, the heating device comprises a heat-conducting plate and a heating element that heats the heat-conducting plate. The fluid is guided along the heat-conducting plate, so that the heat is introduced into the fluid via the heat-conducting plate.

[0015] This design offers several advantages. Firstly, it allows for large-area contact between the heat-conducting plate and the fluid, ensuring rapid heating of the fluid. Secondly, the heat-conducting plate itself can also be heated quickly by the heating element, thus shortening the heating time from the heating element to the heat-conducting plate and then from the heat-conducting plate to the fluid.

[0016] Furthermore, such heat-conducting plates can be manufactured easily, particularly from electrically conductive material, such as metal, so that the heat-conducting plates can also be used to conduct current. Since at least two heat-conducting plates are arranged parallel to each other, a closed circuit to the heating element can be realized via the heat-conducting plates. This heating element is located in the space between the plates, even if multiple heat-conducting plates are used.

[0017] In principle, however, a single heat-conducting plate, to which a heating element is assigned, is sufficient for heat transfer into the fluid. Conveniently, both sides of the heat-conducting plate form flow or heating surfaces for the fluid, which is accordingly guided along both sides of the heat-conducting plate.

[0018] According to the invention, at least two parallel heat-conducting plates are arranged, which define an intermediate flow space. This makes it possible for the fluid to be heated to be guided along both outer sides and in the intermediate space, thus providing a relatively large heating surface despite the limited dimensions of the heat-conducting plate. In this so-called sandwich construction, all side surfaces of the heat-conducting plates expediently serve as flow or heating surfaces. Furthermore, as already mentioned above, at least one heating element is positioned in the intermediate space, with the power supply to the heating element expediently being provided via the heat-conducting plates made of electrically conductive material.

[0019] According to a further advantageous embodiment, a flow opening is provided in the heat-conducting plate through which the fluid to be heated can flow. The flow opening allows the fluid to pass between the axial side surfaces of the heat-conducting plate. The flow is guided past the various side surfaces of the heat-conducting plate by deflections in the area of ​​the heat-conducting plates.

[0020] The heat-conducting plate is disc-shaped, particularly circular or annular, and internally flat, so that a sandwich construction provides a cylindrical or hollow-cylindrical heating device with a heating element located between the parallel and concentrically arranged heat-conducting plates. In this design, the heating device is expediently arranged on one end face of the preferably pot-shaped filter housing, particularly in the cover area, to which the heating device can also be connected.

[0021] However, a design with curved heat-conducting plates is also possible. In the case of a plurality of heat-conducting plates, these are advantageously arranged concentrically to one another to define an intermediate flow space for the fluid to be heated. For example, the heat-conducting plates can be hollow-cylindrical and surround the filter element, which is also hollow-cylindrical, in a ring shape at a radial distance from the upstream side of the filter element.

[0022] In a disc-shaped, particularly annular, flat design of the heat-conducting plate, an arrangement is provided on the inside of the cover of the pot-shaped filter housing, through which the fluid to be cleaned is introduced axially into the housing interior. The fluid first flows through the heating device, which in this design preferably consists of two parallel heat-conducting plates with at least one heating element located between them. Following the heating phase, the fluid is directed to the radial outer side of the filter element, through which the fluid flows radially from the outside to the inside. The cleaned fluid is then discharged via the interior of the filter element in the axial direction.

[0023] The entire filter device can be designed as a disposable part, with the housing cover placed on the filter bowl being firmly connected to the filter bowl by crimping the edge of the cover. According to the invention, the disc-shaped heat-conducting plates are located between the axial end face of the cylindrical filter element and the inside of the housing cover. Both the filter bowl and the filter cover can be designed as metal parts that are tightly connected to one another (flanged, optionally also soldered or welded). The filter device advantageously forms an inseparable unit comprising the filter bowl, filter cover with filter element, heating device, water level sensor, water discharge pipe, and fluid inlet and outlet pipes. The electrical contacts and the water discharge pipe are guided in a plastic part through an opening in the cover and sealed with a sealing ring. The fluid inlet and outlet pipes are soldered to the cover.The electrical conductors for the two contacts for the water level sensor are overmolded in plastic over a large area and thus insulated from each other.

[0024] The heating element is preferably located directly on one of the side surfaces of the heat-conducting plate. In the case of two parallel heat-conducting plates, the heating element is located in the space between the plates. For faster heating, a plurality of heating elements can be provided, arranged either on different sides of the heat-conducting plate or on the same side.

[0025] The heating element is preferably disc-shaped and designed as an electrical PTC element (positive temperature coefficient). Short description of the drawings

[0026] Further advantages and practical embodiments can be found in the further claims, the description of the figures, and the drawings. They show: Fig. 1 a section through a fuel filter with a heating device arranged on the inside of the housing cover, Fig. 1a an enlarged view of the contact area between a drainage channel and a central pipe carrying the filter element, Fig. 3 the heating device, shown with a heating support on the inside of the lid, Fig. 4 the heating device with a first heat conducting plate on the heating support, Fig. 5 the heating device with a second heat conducting plate.

[0027] In the figures, identical components are provided with identical reference symbols. Embodiment(s) of the invention

[0028] At the Fig. The filter device 1 shown in Figure 1 is a fuel filter consisting of a cylindrical, pot-shaped filter housing 2 with a housing cover 3 and an annular or hollow-cylindrical filter element 4 that can be inserted into the filter housing 2 and is provided with an internal, framework-like plastic center tube 24. An inlet connection 5 for the introduction of the fluid to be cleaned is arranged on the housing cover 3, which is to be firmly connected to the axially free end face of the filter housing 2 by means of a flanged edge 3a. The fluid fed into the interior of the housing is heated in a heating device 6 and then, as shown by the arrows, guided to the outside of the annular filter element 4, which also represents the dirty side.The heated, uncleaned fluid is then directed radially from the outside to the inside through the material of the filter element 4 and discharged axially via an outlet nozzle 7, which is also located in the region of the cover 3. Filter paper is used as the filter material for the filter element 4, although fleece or a combination of various filter materials familiar to those skilled in the art is also suitable. Both the fluid inlet nozzle 5 and the fluid outlet nozzle 7 pass through recesses in the cover 3. The outlet and inlet nozzles for the fuel are tightly connected to the cover, for example, by soldering.

[0029] Between the pot base 8 and the axial underside of the filter element 4, there is a water intake chamber 9 inside the housing, in which separated water can collect. A drainage channel 10 opens into the water intake chamber 9 and extends upwards to a water outlet nozzle 11, with which it is fluidly connected. The water collected in the water intake chamber 9 can be discharged via the water outlet nozzle 11. The water outlet nozzle 11 protrudes through a recess in the cover 3. The separated water is forced out by the pressure in the fuel system as soon as the water outlet nozzle 11 or a hose or line section attached to it is opened. This differs from prior art systems with a water drain screw, in which the water is discharged by gravity.

[0030] Furthermore, a connection block 12 is arranged on the outside of the housing cover 3, which serves in particular for electrically contacting the heating device 6 and the water level sensor 22. Components of the connection block 12 are contact pins 23, which also extend through a recess in the cover 3. The metal contact pins 23 provide an electrical connection to a water level sensor 22, which is arranged in the lower part of the drainage channel 10 and via which the current water level in the water intake chamber 9 can be detected. To create an electrically closed circuit, the two contact pins 23 are each connected to a conductor, wherein the two conductors are injected into the wall of the drainage channel 10 and lead to the sensor 22, which has two electrical contacts, each assigned to a conductor, which are electrically connected to one another by the rising water level.A total of three contact pins are provided for the electrical supply of the heating device 6 and the water level sensor 22, since the neutral conductor of the two units can be combined into one contact pin.

[0031] An O-ring 27 is placed around each contact pin 23, via which a flow-tight seal is achieved to a heater support 15 in which the contact pins 23 are accommodated.

[0032] Located on the inside of the lid is the plastic heater support 15, which supports heating elements 16. The water outlet nozzle 11 is designed separately from the heater support 15, but can also be formed as a single piece with the heater support 15 if necessary.

[0033] The fluid inlet nozzle 5 and the fluid outlet nozzle 7 communicate with the heater support 15, but are formed by the cover. In an alternative embodiment, these nozzles can also be formed integrally with the heater support. Furthermore, the drainage channel 10 is also coupled to the heater support 15, wherein the drainage channel 10 is designed as a separate component. However, if necessary, it is expedient to also design the drainage channel integrally with the heater support. Located in the heater support 15 is a channel that connects the drainage channel 10 to the water outlet nozzle 11. An O-ring 28 is placed around the upper section of the heater support 15, which contains the channel communicating with the drainage channel 10 and the water outlet nozzle 11, to seal the heater support 15 against the cover 3.To connect the heating support 15 and the water outlet nozzle 11, a fir tree profile can be arranged on the water outlet nozzle 11 and / or on a section of the heating support 15 to firmly connect the components. The heating elements, the water outlet nozzle, the drainage channel, and the contact pins 23 are thus assigned to the heating support 15. Together with the water level sensor 22, which is arranged on the drainage channel 10, these components form a common, prefabricated module, which is inserted into the cover during assembly and secured by attaching the filter housing. A spring element 26 acts on the filter element 4, thus non-positively securing the module to the inside of the cover. In this way, component and assembly tolerances in the axial direction of the filter device are compensated.

[0034] In an alternative design, the prefabricated module is inserted into the filter housing during assembly and fixed by putting on the cover.

[0035] All connections are made via the cover side, as both the electrical contact pins and the water outlet nozzle protrude through recesses in the cover. The fluid inlet nozzle 5 and the fluid outlet nozzle 7 are attached to the cover and communicate with the interior of the filter housing through an opening.

[0036] A circumferential sealing lip 29 is formed on the heater support 15, which forms a sealing contact with the inside of the filter housing 2. A further sealing lip 30 is formed on an end plate that closes off the cylindrical filter element at the top. This sealing lip 30 also forms a sealing contact with the inside of the filter housing 2. However, it does not extend over the entire circumference, but rather exposes an angular segment so that the fuel heated in the heater support 15 can flow downward from the area above the filter element to the raw side of the filter element.

[0037] These sealing lips 29, 30 define the fuel flow area in the area of ​​the heater support. This prevents the fluid from flowing past the heater 6 and along the filter housing wall into the area of ​​the filter element 4. The sealing lips 29, 30 can be made of the same material and integral with the heater support 15 (sealing lip 29) or with the end plate of the filter element 4 (sealing lip 30).

[0038] In Fig. Figure 1a shows a section of the contact area between the drainage channel 10 and the central pipe 24. A sealing lip 25 is formed on the outside of the drainage channel 10 and is in contact with the central pipe 24. This creates a flow-tight connection between the drainage channel 10 and the central pipe 24 with the filter element 4, eliminating the need for additional sealing measures such as sealing rings.

[0039] Such a seal by means of molded sealing lips is expediently also provided on the outlet nozzle 7 opposite the heating support 15 or a component connected to the drainage channel, so that additional sealing elements can also be omitted on the outlet nozzle 7.

[0040] The heating device 6 is located axially between the upper end face of the filter element 4 and the inside of the housing cover 3. The heating device 6 comprises two heat-conducting plates 13 and 14, which are ring-shaped and arranged centrally to the central longitudinal axis of the filter device 1. The two heat-conducting plates 13 and 14, which consist in particular of an electrically conductive material, preferably a metal, are concentric and essentially parallel to one another and enclose an intermediate fluid space 17. The two heat-conducting plates 13 and 14 are heated by heating elements 16, which are preferably arranged between the two heat-conducting plates 13 and 14.

[0041] For heating, the supplied fluid is guided over the outer and inner sides of the heat-conducting plates 13 and 14, respectively. The flow is expediently guided in such a way that the fluid first sweeps over the outer side of the heat-conducting plate 13 facing the heating support 15, which is then guided into the intermediate fluid space 17. The flow is then directed to the outer side of the lower heat-conducting plate 14 facing the filter element 4, whereupon the flow enters the tube space between the outer side of the filter element 4 and the inner side of the pot-shaped filter housing 2, axially in the region of the filter housing 2.

[0042] The heating support 15 is expediently designed as a plastic component and carries both heat conducting plates 13 and 14. A thermoplastic plastic with glass filling, for example polyamide PA6 with glass fiber filling, is particularly suitable for this purpose.

[0043] In the Fig. 3 to 5, the heating device 6 is shown in various stages of assembly in a perspective directed towards the inside of the cover 3. The raw fluid flows through an inlet opening 18 to the inside of the cover 3 for heating, wherein the inlet opening 18 is introduced into the cover and is connected to the inlet nozzle 5 ( Fig. 1, Fig. 2). Located on the inside of the cover 3 is the heater support 15, which supports the heat-conducting plates. As indicated by the flow arrows, the flow initially circulates circumferentially between the inside of the cover 3 and the outside of the nearest heat-conducting plate, which is arranged parallel to the inside of the cover.

[0044] In Fig. 4, the heating device 6 is shown with the first heat conducting plate 13, which has a flow opening 19 through which the fluid flows from the flow space between the inside of the cover and the outside of the heat conducting plate 13. As indicated by the arrows, the fluid can then flow in the opposite direction to the flow as in Fig. 3 flow in the circumferential direction along the inside of the heat conducting plate 13.

[0045] Heating elements 16, preferably designed as electrical PTC elements, are also arranged on the inside of the heat-conducting plate. These elements heat the heat-conducting plates. Heat is then transferred from the heated heat-conducting plates to the fluid flowing along the side surfaces of the heat-conducting plates. A total of three heating elements 16 are provided, distributed around the circumference.

[0046] The heat conducting plate 13 is just like the heat conducting plate 14 ( Fig. 5) is ring-shaped and has a central recess through which, for example, the outlet nozzle 7 for discharging the purified fluid is guided. Furthermore, the heat-conducting plates are not continuous, but extend only over an angular segment of approximately 330°, with connections 20 being arranged in the remaining free segment, which connections are in particular part of the connection block 12 ( Fig. 1) are.

[0047] In Fig.Figure 5 shows the heating device 6 in its fully assembled state. The second heat-conducting plate 14 is also mounted on the heating support 15 and is parallel to, and spaced from, the first heat-conducting plate 13 below it. A further flow opening 21 is provided in the second heat-conducting plate 14, through which the fluid from the intermediate fluid space between heat-conducting plates 13 and 14 can pass. The fluid then flows circumferentially along the outside of the second heat-conducting plate 14, as indicated by the arrows. The fluid is then heated and can be directed to the raw side of the filter element.

Claims

[1] Filter device for fluids, in particular for the fuel of an internal combustion engine, with a hollow cylindrical filter element (4) arranged in a filter housing (2) through which the fluid flows in the radial direction and with a heating device (6) arranged in the flow path of the fluid, which heating device is arranged on the inside of a cover (3) closing the filter housing, wherein the cover (3) is firmly connected to the filter housing (2), characterized bythat the heating device (6) comprises at least two parallel disc-shaped heat-conducting plates (13, 14) and a heating element (16) located in the space between the heat-conducting plates (13, 14), which is held on a heating support (15) arranged on the inside of the cover, wherein the heat-conducting plates (13, 14) can be heated by the heating element (16) and the fluid to be heated is guided along the outer sides and a flow space located between the heat-conducting plates (13, 14), and that the heat-conducting plates (13, 14) are located between an axial end face of the filter element (4) and the inside of the housing cover (3), wherein a water outlet nozzle (11) is formed separately from the heating support (15), which is guided to the outside through a recess in the cover (3), wherein the water outlet nozzle (11) is connected to a drainage channel (10) in the filter housing (2) which is connected to the heating support (15). [2] Filter device according to claim 1, characterized by that at least one electrical contact pin (23) is connected to the heating support (15) and is guided through a recess in the cover (3). [3] Filter device according to claim 2, characterized by that a contact pin (23) is connected to a water level sensor (22) which is arranged in the filter housing (2). [4] Filter device according to claim 3, characterized by that the water level sensor (22) is arranged in or on the drainage channel (10). [5] Filter device according to one of claims 1 to 4, characterized by that the heating support (15) is designed as a plastic part. [6] Filter device according to one of claims 1 to 5, characterized by that sealing lips (25) are formed on the drainage channel (10) and are in sealing contact with a central tube (24) carrying the filter element (4). [7] Filter device according to one of claims 1 to 6, characterized bythat a fluid inlet nozzle (5) and a fluid outlet nozzle (7) are connected to the heating support (15) and are guided through recesses in the cover (3). [8] Filter device according to claim 7, characterized by that sealing lips are formed on the outlet nozzle (7) for sealing against the heating support (15) or a component connected to the drainage channel (10). [9] Filter device according to one of claims 1 to 8, characterized by that the heat conducting plate (13, 14) is electrically conductive and part of the electrical circuit for heating the heating element (16). [10] Filter device according to one of claims 1 to 9, characterized by that the cover (3) is firmly connected to the filter housing (2) by flanging the edge of the cover.

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