DE102017202582A1 - Fuel filter device for an internal combustion engine - Google Patents

Abstract

The invention relates to a fuel filter device (1) for an internal combustion engine. The fuel filter device (1) comprises a ring filter element (2), through which a fuel (8) can flow, which separates a raw side (3) from a clean side (4). The fuel filter device (1) further comprises a water separator (6) which is designed as an electric coalescer (5) and for the separation of water (7) from the fuel (8) has two electrodes (10, 11) and an electrical voltage source (23). which is electrically connected to the two electrodes (10, 11) for generating an electrode voltage. With the aid of a control device (24) cooperating with the electrical voltage source (23), the electrical coalescer (5) can be switched to an electroporation mode in which the electrical voltage source (23) generates a pulsating electric field between the two electrodes (10, 11).

Description

The present invention relates to a fuel filter device for an internal combustion engine and an internal combustion engine having such a fuel filter device.

In modern fuel supply systems, water separators are usually used in the associated fuel filter devices in order to lower as far as possible a water content contained in the fuel. If the water contained in the fuel is not separated and separated, it can lead to undesired corrosion, abrasion, material embrittlement and cavitation in the following units. Likewise, an increased proportion of water in the fuel supply system leads to a growth promotion of microorganisms, which cause a mucus of the fuel filter device and can cause increased corrosion on the filter housing. As a water separator so-called coalescers are usually used, which coalesce the smallest portions of water to larger water droplets and deposit them by gravity from the fuel-water emulsion. If necessary for the separation of water, a so-called end separator consisting of a hydrophobic tissue can also filter out the drops of water contained in the fuel-water emulsion. The water separated in this way is then collected in separate water collecting chambers, from which it is drained periodically or at the latest when a filter element is replaced.

Against this background is from the DE 10 2010 062 813 A1 a filter device for an internal combustion engine of a motor vehicle, in particular a fuel or lubricant filter, with a filter housing and a arranged in this and in the radial direction from a raw side to a clean side perfused ring filter element known. On the clean side of the filter element and below it, a water separator is arranged, which has a continuous from radially outside to radially inward for fuel / lubricant, hydrophobic and extending in the axial direction of the filter element, annular membrane. This is a classic coalescer, which in combination with an end separator should improve the water separation efficiency.

Due to the presence of biogenic components, especially in diesel fuels, the importance of devices for controlling the contamination of fuels with microorganisms is increasingly becoming the focus of modern research. Because fungi and bacteria are able to multiply in fuels and to metabolize them, among other things, water can be formed.

As a result, however, the functionality of fuel supply system and engine components of a motor vehicle can be affected primarily by corrosion-related damage. The microbial growth and the accumulation and deposition of microorganisms to system components but can also lead to wear of said components, so that in extreme cases a trouble-free operation of motor vehicles is no longer guaranteed.

In particular, the known to those skilled in the diesel fungus "Hormoconis resinae" can enforce engine and engine peripheral components of a motor vehicle to a considerable extent, so that appropriate countermeasures for a failure-free use of internal combustion engines are essential.

The present invention therefore deals with the problem of providing a fuel filter device with an improved embodiment, by means of which good separation values for the water contained in the fuel can be achieved and by means of which the contamination by microorganisms contained in the fuel can be counteracted simultaneously.

This problem is solved according to the invention by the subject matters of the independent claims. Advantageous embodiments are the subject of the dependent claims.

The basic idea of the invention is therefore to use an electric coalescer not only in conjunction with an end separator for separating water for the water contained in the fuel, but to subject the microorganisms present in the fuel by means of the electric coalescer to electroporation, so that these at least partially, ideally even completely killed.

By electroporation is meant in the present case a permeabilization of the cell walls of the microorganism-forming cells, for which purpose they are exposed to a pulsating external electric field. This pulsating electric field is generated in an electrorporation mode by the electric coalescer. The permeabilization of the cell walls, ie the temporary increase in cell wall permeability, causes intracellular cell components to be released.

In this process, under the action of the electric field generated by the coalescer, the electric charge carriers present in the cells and lying outside the cells become polarized. This leads to a field-induced transmembrane potential or to a membrane voltage. However, the cell wall or cell wall of a respective cell is only broken when the field strength of the electric field generated between the electrodes is high enough. The value of the critical field strength at which the cell wall is perforated by creating breakthroughs can be calculated and depends inter alia on the mean diameter of the respective cells of the respective microorganism. For cells with smaller diameters, a higher field strength is required for the membrane breakthrough than for those with larger diameters. With a sufficiently long residence time in the electric field, this ultimately leads to the death of the cells.

In addition to the foregoing advantages resulting from the control of microorganisms contained in the fuel, the use of an electric coalescer in conjunction with an end separator also permits effective separation of water from the fuel passed through the coalescer. As compared to conventional coalescers with corresponding coalescer materials, an electrical coalescer is subject to little or no wear and can thereby remain in the same throughout the life of the fuel filter device. As a result, in particular the maintenance costs for such a fuel filter device can be significantly reduced. In addition, an electric coalescer has a greater insensitivity to the composition of the fuel, other additives and water, without affecting the coalescer efficiency. In addition, it is of particular advantage that an electrical coalescer, in interaction with an end separator, offers the possibility of influencing the specific parameters of the coalescing process, for example the drop movement or droplet formation, individually. Of particular advantage in the inventive arrangement of the two electrodes of the water separator is also that they can be arranged at previously unoccupied points, whereby the fuel filter device according to the invention can be constructed extremely compact.

By dispersing water into fuel, a water-fuel emulsion is generated. It is a binary system, the essential feature of which is the formation of a miscibility gap that extends over almost the entire concentration range. Due to the thermodynamic instability of the system, this aims at a state that represents a minimum in terms of energy. The separation of the two phases is thus accelerated until finally there is complete phase separation. In order to intensify the demulsification process in a water-in-fuel emulsion, the beneficial effect of the presence of an electric field is now utilized. The process of droplet coalescence is forced by the polarizing effect of the applied electric field. The forces occurring in the electric field cause an increase in the mobility of the water droplets, this consequently leads to a higher collision rate, which in turn has a positive effect on the droplet coalescence. The drops thus combine to form larger drops and flow together. If the drops are correspondingly large, gravity outweighs and the specific denser water phase decreases.

A fuel filter device according to the invention for an internal combustion engine comprises a ring filter element, through which fuel can pass, for separating dirt particles from the fuel, which separates a raw side from a clean side. The fuel filter device further comprises a water separator, which in turn comprises an electric coalescer with two electrodes for coalescing water contained in the fuel and an end separator for separating the water from the fuel. The electrical coalescer also includes an electrical voltage source electrically connected to the two electrodes for generating an electrode voltage.

Furthermore, the fuel filter device comprises a control device cooperating with the electrical voltage source, by means of which the electrical coalescer can be switched to an electroporation mode. In the electroporation mode, the electrical voltage source generates a pulsating electric field between the two electrodes.

According to a preferred embodiment, a single pulse of the pulsed electric field generated between the electrodes has a maximum value of at least 1 kV / cm, preferably of at least 50 kV / cm. In this way, an undesirable regeneration of the cells in the time interval between two pulses can be counteracted.

According to another preferred embodiment, a pulse timing of the pulsed electric field generated between the electrodes is at least 100 pulses per second, preferably at least 1000 pulses per second. Also by means of this measure, the unwanted regeneration of the cells in the time interval between two pulses can be effectively counteracted.

In an advantageous development of the electric coalescer by means of the control device in a Wasserabscheidemodus be switched. In the water separation mode, the electric coalescer does not generate a pulsating electric field. in the Wasserabscheidemodus follows the electric coalescer in conjunction with the Endabscheider the operating principle of a water separator.

Particularly preferably, the electrical voltage source in Wasserabscheidemodus generates a non-pulsating electric field, in particular a temporally constant electric field or an alternating electric field. In this way, the water contained in the fuel can be separated very effectively.

According to a preferred embodiment, the water separator is arranged with the electric coalescer on the clean side within the ring filter element. In this embodiment, the two electrodes extend along a longitudinal direction, which preferably extends coaxially to a filter axis or a central longitudinal axis of the ring filter element. The two electrodes thus limit a flow path through which the fuel can flow.

In a further advantageous development, the fuel filter device is designed to flow through with a fuel whose dielectric conductivity has at most a predetermined maximum value. In this development, at least one of the two electrodes comprises an electrode material-or consists of an electrode material-whose dielectric conductivity has a greater value than said predetermined maximum value. Preferably, this value is at least twice, most preferably at least five times the predetermined maximum value. Particularly preferably, the above applies even for both electrodes. By said measures, a displacement of the electric field is achieved in the flowing through the electric coalescer fuel. This in turn is accompanied by an increased electrical voltage drop across the fuel, so that a particularly strong electric field acting on the microorganisms is generated.

Particularly advantageously, the at least one dielectric property comprises or is the relative dielectric conductivity of the fuel. This can be quantified particularly easily by means of capacitive measurement and from this the fuel quality actually present can be determined.

According to a preferred embodiment, the electrical coalescer has an electrical measuring device for determining the dielectric properties, in particular the relative dielectric conductivity, of the fuel carried by the coalescer. The two electrodes are part of the electrical measuring device in this embodiment. By means of the electrical measuring device can thus be carried out using the two electrodes in a particularly simple manner, a capacitive measurement for determining the relative dielectric conductivity of the fuel through the flow path.

In a preferred embodiment, therefore, the two electrodes and the fuel guided through the flow path together form an electrical capacitor with a complex electrical impedance, which can be determined by means of the electrical measuring device.

In a further advantageous development, the fuel filter device is designed to flow through with a fuel whose dielectric conductivity has at most a predetermined maximum value. In this development, at least one of the two electrodes comprises an electrode material or consists of an electrode material whose dielectric conductivity has a greater value than the predetermined maximum value. Preferably, this value is at least twice, most preferably at least five times the predetermined maximum value. Preferably said above even for both electrodes. In this way, a displacement of the electric field is achieved in the flowing through the electric coalescer fuel. This in turn is accompanied by an increased electrical voltage drop across the fuel, so that a particularly strong electric field acting on the microorganisms is generated.

In another advantageous development, a first of the two electrodes is an internal electrode and a second of the two electrodes is an external electrode. In this development, the two electrodes limit the flow path designed as an annular channel for flowing through with the fuel. Preferably, the external electrode is electrically connected to an electrical ground potential or at least connected to such. As a result, susceptibility to interference can be avoided, which are caused by external electrical and magnetic fields.

Suitably, at least one electrode may be designed as two-component injection-molded electrodes. In this case, an electrically conductive plastic forms an inner component. Said inner component is encased externally by a second, electrically insulating outer component. Particularly expedient both electrodes are formed as described above.

In an advantageous embodiment, the two electrodes for limiting the annular channel are each tubular and limit a ring channel. In the installed state, this annular channel particularly preferably has tangentially directed inflow openings arranged at the top, which force a helical flow of the fuel in the annular channel. This measure increases the cross section of the electric coalescer.

The invention further relates to an internal combustion engine with a previously presented fuel filter device. The above-explained advantages of the internal combustion engine are therefore also transferred to the internal combustion engine according to the invention.

Other important features and advantages of the invention will become apparent from the subclaims, from the drawing and from the associated description of the figures with reference to the drawings.

It is understood that the features mentioned above and those yet to be explained below can be used not only in the particular combination given, but also in other combinations or in isolation, without departing from the scope of the present invention.

Preferred embodiments of the invention are illustrated in the drawings and will be explained in more detail in the following description.

• 1 eine erfindungsgemäße Kraftstofffiltereinrichtung in einer schematischen Darstellung,
• 2 ein die Ausbildung des elektrischen Feldes als Puls illustrierendes Feldstärke-Zeit-Diagramm.
• 3a, 3b das Funktionsprinzip der Elektroporation illustrierende Darstellungen.

Show it:

• 1 a fuel filter device according to the invention in a schematic representation,
• 2 a field strength-time diagram illustrating the formation of the electric field as a pulse.
• 3a . 3b the functional principle of electroporation illustrative representations.

Corresponding 1 which is a sectional view through a fuel filter device according to the invention 1 shows, the fuel filter device 1 for an otherwise not shown internal combustion engine one of fuel 8th flow-through ring filter element 2 on, this is a raw page 3 from a clean side 4 separates. The ring filter element 2 serves to separate dirt particles from the fuel 8th ,

In addition, the fuel filter device 1 a water separator 6 on, in turn, an electric coalescer 5 with two electrodes 10 . 11 for separating a polar phase, in particular for coalescing in the fuel 8th contained water 7 , and an end separator 16 for separating the water 7 from the fuel 8th , The electric coalescer 5 also includes an electrical power source 23 for electrically generating the electrode voltage V with the two electrodes 10 . 11 connected is.

In the example scenario, the water separator 6 with the electric coalescer 5 on the clean side 4 within the ring filter element 2 arranged.

Considering the fuel filter device 1 according to 1 , so you can tell that the two electrodes 10 . 11 are tubular and have a flow path 21 in the form of a ring channel 12 limit, in the installed state of the fuel filter device 1 arranged above, tangentially directed inlet openings 13 which has a helical flow of fuel 8th in the ring channel 12 or in the flow path 21 force.

Like the representation of the 1 clearly demonstrated, a first of the two electrodes 10 an internal electrode and a second of the two electrodes 11 an external electrode. The internal electrode 10 and the external electrode 11 together limit the flow path formed as a ring channel 12 21 for flowing through with fuel 8th , It proves to be advantageous if the external electrode 11 with an electrical ground potential 15 connected is.

The through the fuel filter device 1 and its ring filter element 2 from the raw side 3 to the clean side 4 flowing fuel 8th is initially along the outside electrode 11 deflected upwards until it reaches the inflow openings 13 reached. Since they open in the tangential direction in the annular channel 12, which is through the inlet openings 13 in the ring channel 12 incoming fuel 8th forced a helical flow or a helical flow, which on the one hand to a prolonged contact with the two electrodes 10 . 11 and associated with it leads to an improved water separation. The heavier water droplets 7 are due to the adjusting centrifugal forces to the outside to the outside electrode 11 thrown and flow down along this. At the bottom of the internal electrode 10 is an end separator 16 provided, which has a sound beaker-like intermediate piece 17 into the internal electrode 10 passes. On the intermediate piece 17 are again flow guide 18 , For example, ribs arranged, which on the one hand further increase the coalescence and on the other hand, the already coalesced water droplets 7 radially outward in the direction of a housing wall 19 to hurl. From there they can then go down into one below the end separator 16 located water collection room 20 fall. The fuel 8th whereas it passes through the final separator 16 through and flows through a through the hollow internal electrode 10 formed pure channel 22 up from the fuel filter device 1 out.

The two electrodes 10 . 11 extend along a longitudinal direction L coaxial with a filter axis 9 of the ring filter element 2 - In the example scenario, the filter axis 9 a central longitudinal axis 26 the cylindrical ring filter element 2 - runs. The two electrodes 10 . 11 are arranged transversely to the longitudinal direction L at a distance from each other, so that the flow path 21 or the annular channel 12 is narrowed laterally. In this way it is ensured that the entire fuel flowing through the annular channel the fuel between the electrodes 10 . 11 generated electric field is exposed.

The two electrodes 10 . 11 and the through the flow path 21 or the annular channel 12 guided fuel 8th together form an electrical capacitor 25 with a complex electrical impedance Z out.

The fuel filter device 1 according to 1 can flow through with a fuel 8th be furnished, the dielectric conductivity ∈ _{r has} at most a predetermined maximum value. At least one of the two electrodes 10 , 11 consists of an electrode material whose dielectric conductivity has a greater value than the predetermined maximum value described above.

The two electrodes 10 . 11 can be designed as two-component injection-molded electrodes. In this case, an electrically conductive plastic form an inner component of the respective injection-molded electrode, which is encased externally by a second, electrically insulating outer component.

The fuel filter device 1 according to further comprises an electrical voltage source 23 for electrically generating the electrode voltage with the two electrodes 10 . 11 is connected, and one with the electrical voltage source 23 cooperating control device 24 , By means of the control device 24, the electric coalescer 5 be switched to an electroporation mode. In electroporation mode generates the electrical voltage source 23 between the two electrodes 10 . 11 a pulsating electric field.

The 2 shows a voltage-time diagram, in which, for example, a possible time course of several electrical voltage pulses 27 , which by means of the electrical power source 23 at the two electrodes 10 . 11 , are generated in Elektroporationsmodus shown. Preferably, the time profile of the electrical voltage as in 2 shown rectangular. This also applies to the electrical field associated with the electrical voltage generated between the two electrodes.

A single electrical pulse 27 in the electroporation mode between the two electrodes 10 . 11 generated, pulsating electric field may thus have a maximum value M of at least 1kV / cm. This maximum value M is preferably at least 50 kV / cm. In addition, a pulse timing of the between the electrodes 10 . 11 generated, pulsating electric field at least 100 pulses per second, preferably at least 1000 pulses per second. A pulse duration T of a single pulse 27 of the between the electrodes 10 . 11 generated, pulsating electric field is in 2 purely exemplary between 1ns and 1μs. In variants, of course, other values are conceivable.

By means of the control device 24 is the electric coalescer 5 switch from Elektroporationsmodus in a Wasserabscheidemodus in which the electric Koaleszer 5 in combination with the final separator 16 as a water separator 6 can work. For this purpose, the electrical voltage source generates 23 in said Wasserabscheidemodus a non-pulsating electric field in the form of a time-constant electric field or an alternating electric field (in 2 not shown) or a combination of both (in 2 Not shown).

Based on 3a and 3b The physical principle of electropermeabilization will now be explained schematically. In between the electrodes 10 . 11 generated electric field are those within the cell wall 30 a respective cell 29 - at the cell wall 30 the cell 29 In the present case, these are cell membranes - and those outside the cell wall 30 existing electrical charge carriers 31 polarized. The 3a shows the cell wall 30 before the polarization of the electrical charge carriers 31 , the 3b after polarization.

The polarization of the electrical charge carriers 31 leads to a field-induced transmembrane potential or to an electrical membrane voltage. In other words, on the cell wall 30 the cell 29 falls off an electrical voltage. The cell wall 30 but it is only broken through, ie in the cell wall 30 only then breakthroughs form 28 when the electrical field strength associated with the electrical voltage is high enough. The value of the critical electric field strength, from which the cell wall 30 perforated with breakthroughs 28 can be calculated and depends inter alia on the average diameter of the respective cells 29 from. For cells with smaller diameters becomes a higher field strength for the formation of openings 28 in the cell wall 30 needed as for those with larger diameters.

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 102010062813 A1 [0003]

Claims (11)

Fuel filter device (1) for an internal combustion engine, with a ring filter element (2) which can be flowed through by fuel (8) and which separates a raw side (3) from a clean side (4), - With a water separator (6) comprising an electric Koaleszer (5) with two electrodes (10, 11) for coalescing in the fuel (8) contained water (7) and an Endabscheider (31) for separating the water (7) the fuel (8), wherein the electrical coalescer (5) comprises an electrical voltage source (23) electrically connected to the two electrodes (10, 11), - With a with the electrical voltage source (23) cooperating control means (24), by means of which the electrical coalescer (5) is switched to an electroporation mode, in which the electrical voltage source (23) between the two electrodes (10, 11) a pulsating electrical Field generated. Fuel filter device according to Claim 1 , characterized in that a single pulse (27) of the pulsed electric field generated between the electrodes (10, 11) has a maximum value (M) of at least 1kV / cm, preferably of at least 50kV / cm. Fuel filter device according to Claim 1 or 2 , characterized in that a pulse timing of the pulsed electric field generated between the electrodes (10, 11) is at least 100 pulses per second, preferably at least 1000 pulses per second. Fuel filter device one of Claims 1 to 3 , characterized in that the electrical coalescer (5) is switchable by means of the control device (24) into a Wasserabscheidemodus in which the electric Koaleszer (5) does not generate a pulsating electric field. Fuel filter device according to Claim 4 , characterized in that the electrical voltage source (23) in Wasserabscheidemodus a non-pulsating electric field, in particular a temporally constant electric field or an alternating electric field generated. Fuel filter device according to one of the preceding claims, characterized in that the electric coalescer (5) is arranged on the clean side (4) within the ring filter element (2), the two electrodes (10, 11) extending along a longitudinal direction (L), which preferably runs coaxially to a filter axis (9) or a central longitudinal axis (26) of the ring filter element (2) and delimits a flow path (21) through which the fuel (8) can flow. Fuel filter device according to one of the preceding claims, characterized in that - the fuel filter device (1) is adapted to flow through with a fuel (8) whose dielectric conductivity (∈ _r ) has at most a predetermined maximum value, - at least one of the two electrodes (10, 11), preferably both electrodes (10, 11), has / have an electrode insulation whose dielectric conductivity is greater than the predetermined maximum value and preferably at least twice, most preferably at least five times the predetermined maximum value. Fuel filter device according to one of the preceding claims, characterized in that a first of the two electrodes (10) is an internal electrode and a second of the two electrodes (11) is an external electrode which together form the flow path (21) designed as an annular channel (12). for flowing through with fuel (8) limit, wherein the external electrode (11) with an electrical ground potential (15) is connectable or connected. Fuel filter device according to one of the preceding claims, characterized in that at least one electrode (10, 11), preferably both electrodes (10, 11), is designed as a two-component injection-molded electrodes, wherein an electrically conductive plastic is an internal component formed, which is externally covered by a second, electrically insulating outer component. Fuel filter device according to Claim 8 or 9 , characterized in that the two electrodes (10, 11) for defining the annular channel (12) are each of tubular design, the preferably arranged in the installed state at the top having tangentially directed inflow openings (13) having a helical flow of the fuel (8). in the flow path (21) or in the annular channel (12) force. Internal combustion engine with a fuel filter device (1) according to one of the preceding claims.

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