DE102018131551B4 - Filter system and filter element with telescopic central tube - Google Patents

Abstract

A filter element (10) for fuel comprising:
- At least one central tube (26) through which, in its operating position within the filter element (10), the fuel can flow in a direction that is radial to the longitudinal axis (18) of the filter element (10);
- A connection means (48) arranged on the central pipe (26) for a releasable mechanical connection of the central pipe (26) to a filter housing (102), the central pipe (26) being mounted in the filter element (10) so as to be longitudinally displaceable and out of its operating position within the filter element (10) is displaceable in the axial direction out of the filter element (10) into a maintenance position of the filter element (10), the central tube (26) being lockable, in particular latchable, in the maintenance position relative to the filter element (10).

Description

Technical area

The invention relates to a filter element and a filter system with a telescopic central tube. The filter element is preferably designed as a fuel filter with a water separating function.

State of the art

Fuels, in particular diesel fuels, generally have a predetermined maximum permissible water content. If this permissible maximum value is exceeded, this can lead to malfunctions and damage to injection systems, in particular to highly developed diesel high-pressure pumps, as well as to an internal combustion engine operated with fuel. The fuel is “diluted” by the water it contains and its lubricity decreases, so that the high-pressure pumps can seize up. In addition, metal parts that come into contact with the fuel can rust if they are left in contact with the water it contains for a long time. In practice, water separators are therefore used to separate the water contained in the fuel from the fuel. For this purpose, the water separators have, according to one type, a sieve tube which serves as a final separating sieve for the water contained in the fuel. In its operating or water separation position within the water separator, the sieve pipe can be flowed through by fuel, as a rule, in a direction radial to the longitudinal axis of the water separator and can be designed or equipped to be hydrophobic. A so-called clean side of the water separator, on which the fuel freed from the water is routed, is fluidically connected downstream of the sieve pipe. The water separators are also available as combination filters and for this purpose also have a filter medium in order to filter out particulate impurities contained in the fuel.

For water separation operation, the combination filter elements are arranged in a separator or filter housing with a fuel inlet and a fuel outlet. When replacing the filter element, there is always the risk that untreated fuel, i.e. fuel with water and possibly other impurities, gets onto the clean side of the filter element, which is fluidically downstream of the sieve pipe / final separating sieve. This can lead to an undesired entry of water into the injection system connected to the fuel drain and the aforementioned water-induced problems. By releasing the separator from its sealing seat on the separator housing, a return channel of the separator housing to the interior of the separator housing is usually opened in modern separator systems. When replacing the filter element, it must be ensured that the fuel contained in the filter element and in the separator housing can drain completely downwards before the filter element is completely removed from the separator housing. Otherwise, the engine compartment or the surrounding area may be contaminated with dripping fuel. This is labor and time consuming.

In addition, a known problem is that the above-mentioned dripping of the fuel from the filter element takes some time, a fitter having to hold the filter element during this waiting time in order not to have to take a dripping, fuel-saturated filter element out of the housing, which directly affects the Contaminated environment.
A filter system with a standpipe fixed to the housing is from the DE 10 2011 077 798 A1 known. the EP 3 004 620 B1 describes a filter element with a central water separator (sieve tube).

It is therefore the object of the invention to specify a filter element and a filter system which are improved with regard to at least one service aspect, in particular contamination of the clean side of the filter element by water-containing and / or dirty fuel when the filter element is replaced in a reliable and convenient way .

The problem relating to the filter element is achieved by a filter element having the features specified in claim 1. The filter system according to the invention has the features specified in claim 14. Further developments of the invention are given in the description and in the subclaims.

Disclosure of the invention

In the filter element according to the invention, the central tube has at one end a coupling or connection means for releasably connecting the central tube to a filter housing, the central tube being mounted telescopically, i.e. longitudinally displaceable, in the direction of the longitudinal axis of the filter element.

When the filter element is moved axially out of its operating position within the filter housing, i.e. when the filter element is lifted out of the housing, the central tube connected or fastened to the filter housing can be moved axially out of the filter element into a (telescoped) maintenance position from its operating position in the filter element will. In other words, in the maintenance position, the sieve tube protrudes from the filter element with a defined length section, for example via a water outlet or a lower end plate delimiting the water outlet in the radial direction.

The filter element preferably has at least one filter medium body, which is designed in particular as a filter bellows. The device component over which the central tube or the sieve tube protrudes in the maintenance position is then the filter medium body. In the operating position, however, the central tube or sieve tube is received within the filter medium body. The filter medium body has in particular a cylindrical, preferably hollow cylindrical, shape.

As long as it is connected to the filter housing at one end, the telescopically mounted central tube can serve as a guide for the filter element to be moved out of the filter housing when the filter element is replaced.

According to a preferred embodiment, the filter element has at least one water separator for separating water contained in the fuel, which has a water outlet opening for leading the water separated from the fuel out of the filter element and the central tube, the central tube being designed as a sieve tube.

The advantage of such an embodiment is that a clean side of the filter element fluidically downstream of the filter element can be effectively protected against contamination with water-based fuel by the filter element when the filter element is replaced, until the contaminated fuel has completely drained from the filter element / filter housing. With regard to its function as a final separator for water droplets contained in the fuel, the sieve tube must have a mesh size of 10 to 30 µm. In this way, at the same time, an undesired entry of larger particulate impurities onto the clean side of the filter element / filter housing can be reliably counteracted. For the reasons mentioned above, the filter element can only be separated from the filter housing with its sieve tube after the fuel has largely / completely drained off.

The central tube or sieve tube can be locked in its telescoped maintenance position on or relative to the filter element. In other words, in its maintenance position, the central tube or sieve tube can be releasably fixed in position on the filter element in the axial direction. As a result, the filter element does not have to be laboriously held by an operator while the fuel drains out of the filter element in order to prevent undesired insertion of the central tube or sieve tube into the filter element, which considerably improves the service aspect. Overall, this further simplifies the handling of the filter element when it is replaced.

Particularly simple and safe handling and assembly of the filter element within a filter housing can be achieved in that the central tube or sieve tube can be detachably latched on the filter element, for example one of its end plates, in its operating position or water separation position within the filter element. An unintentional slipping out of the central tube or sieve tube from the filter element can be reliably avoided.

The connecting means of the central tube or sieve tube can in particular comprise a sealing collar (= sealing or connecting sleeve) or be designed as such. As a result, the central tube or sieve tube can be plugged onto a housing or fuel nozzle of the filter housing in a sealing manner. Alternatively or additionally, the connection means can have a latching element or a bayonet element for the detachable mechanical connection of the sieve tube to the filter housing. Such a locking or bayonet element can advantageously be molded onto the central tube or sieve tube.

According to a preferred development of the invention, the central tube or sieve tube delimits a flow channel for the fuel, which is fluidically connected to an axial opening of the central tube or sieve tube. The opening can in particular form the clean-side fuel outlet of the filter element for the fuel from which the water has been removed. In this case, the central tube or sieve tube can be designed to be open at both ends, which further simplifies the manufacture of the sieve tube in the plastic injection molding process. This offers cost advantages. In addition, the central tube or sieve tube can be stiffened in a simplified manner by longitudinal and / or transverse ribs. By combining the named longitudinal and transverse ribs, the central tube or sieve tube can be made particularly pressure-resistant, so that it also withstands the static or dynamic pressure loads of the fluid that occur during operation of the filter element.

According to a preferred development of the invention, the filter element can have a coalescing medium and / or a filter medium for filtering out particulate impurities contained in the fuel. The coalescing medium or the filter medium can be flowed through by the fuel, preferably in a direction that is radial to the longitudinal axis of the filter element, from the outside to the inside. To support the coalescing medium or Filter medium, the filter element can have a, in particular grid-shaped, central tube. According to the invention, the coalescing medium or the filter medium can be arranged between two end plates. The filter medium is preferably designed as an annularly closed bellows made of folded filter medium. The filter medium and / or coalescing medium are arranged coaxially around the central tube, which in turn is arranged coaxially around the central tube or sieve tube.

The sieve tube and the central tube advantageously delimit, at least in sections, a water separation gap in a direction which is radial to the longitudinal axis of the filter element and which is fluidically connected to the water outlet opening. Such a water separation gap enables a calmed flow zone for the fuel, so that water droplets contained in the fuel can settle downwards following the force of gravity. The water can flow out of the water separation gap via the water outlet opening.

In the structurally simplest case, the central tube or sieve tube or final separating sieve is, according to the invention, mounted telescopically directly on the central tube. This eliminates the need for additional components in order to move the central tube or sieve tube translationally out of the operating or water separation position inside the filter element and the central tube into the telescoped maintenance position of the filter element.

According to the invention, the central tube or sieve tube and the central tube can be coupled to one another in a rotationally fixed manner, for example via a tongue and groove pairing. As a result, the filter element together with the central tube or sieve tube can be released from its seat on / in the filter housing in a simplified manner.

The filter system according to the invention for fuel with water separation comprises a filter housing and a filter element explained above, which is arranged in the filter housing. The filter system is particularly easy to maintain and enables a further improved protection of the clean side from undesired contamination with dirty fuel.

Figure list

• 1 ein erfindungsgemäßes Filterelement mit Wasserabscheider zum Abscheiden von in Kraftstoff enthaltenem Wasser, mit einem teleskopierbaren Siebrohr, das in seiner für das Abscheiden des Wassers vorgesehenen Betriebsstellung innerhalb des Filterelements angeordnet ist, in einem Längsschnitt; und
• 2 das Filterelement aus 1 mit aus dem Filterelement heraus bewegtem Siebrohr, das in der Wartungsposition angeordnet und in dieser am Filterelement verrastet gehalten ist, in einem Längsschnitt.

In the drawing show:

• 1 a filter element according to the invention with a water separator for separating water contained in fuel, with a telescopic screen tube which is arranged in its operating position provided for separating the water within the filter element, in a longitudinal section; and
• 2 the filter element off 1 with the sieve tube moved out of the filter element, which is arranged in the maintenance position and is held locked in this position on the filter element, in a longitudinal section.

Embodiment of the invention

1 shows a filter element 10 with filtering fuel with a water separator for separating water contained in fuel, in particular diesel fuel. The filter element 10 has an upper and a lower end plate 12th , 14th on that via a lattice-shaped central tube 16 are connected to each other. The central tube 16 is to the longitudinal axis 18th of the filter element arranged to run coaxially. The filter element 10 is with the in 1 The embodiment shown is designed as a combination filter and has a filter medium 20th to filter out particulate contaminants contained in the fuel. The filter medium 20th is between the two end plates 12th , 14th arranged and for example as a star-shaped folded bellows in a ring around the longitudinal axis 18th of the filter element 10 arranged around. The filter medium 20th is fluid-tight at both ends in the material of the two end plates 12th , 14th kept embedded to bypass flow of the fuel around the filter media 20th around to counteract. Alternatively, the filter medium 20th also on the two end plates 12th , 14th be stuck on.

A coalescing medium 22nd is in one of the filter media 20th corresponding way to the longitudinal axis 18th of the filter element 10 arranged in a ring. The coalescing medium 22nd and filter medium 20th are together in the radial direction on the central tube 16 and when the filter element is in operation, the fuel flows through it in the radial direction from the outside to the inside, as indicated by the dashed arrow lines 24 is made clear.

Inside the central tube 16 is a hydrophobic tubular, as a final separating sieve or sieve tube 26th formed central tube 26th arranged for the water contained in the fuel. The sieve pipe 26th has a mesh size between 15 and 30 µm, in particular approximately 20 µm. For stiffening the sieve tube 26th serve longitudinal and transverse ribs 28 , 30th . Coalescing medium 22nd and sieve tube 26th are part of the water separator of the filter element 10 .

Between the sieve tube 26th and the central tube 16 is a water separation gap with an annular cross section 32 educated. The water separation gap 32 forms a calmed flow zone for the fuel, so that water droplets contained in the fuel can settle downwards in the axial direction following the force of gravity. The water separation gap 32 is carried out openly at one end and with a water outlet opening 34 of the filter element fluidly connected. The water outlet opening 34 is in the lower end plate 14th be trained.

The sieve pipe 26th forms a flow channel inside 36 for the fuel that has been at least partially freed from the water. The flow channel 36 is thus the sieve tube 26th and the filter medium 20th downstream fluidically and therefore on the so-called clean side 38 of the filter element 10 arranged. The flow channel 36 has one at the water outlet end of the sieve tube 26th formed opening 40 on.

The filter element can be a vent pipe 42 have that in operational use of a venting of the clean and / or the raw side of the filter element 10 serves. The vent pipe shown 42 is the sieve tube 26th integrally formed, but can alternatively also be retained on this, for example latched, and ventilates the raw side. The vent pipe 42 can in particular be arranged to run coaxially to the longitudinal axis of the filter element. The vent pipe 42 is designed to be fluid-tight in the radial direction and has a radial sealing element on its water outlet-side (lower) end section 44 for a sealing connection of the ventilation pipe 42 to a vent port of the filter housing mentioned at the outset. The vent pipe 42 has a further radial sealing element at its upper end portion 44 over which the vent pipe 42 in the shown operating position of the filter element 10 at a recess in the upper end disk 12th of the filter element 10 rests completely sealingly in the radial direction. The upper end disk 12th has a small throttle hole 46 for ventilation purposes.

How out 1 shows the sieve tube 26th at its lower end a connecting means designed as a sealing collar or sealing collar 48 for a detachable mechanical connection of the sieve tube 26th on the filter housing. The sealing collar is elastically deformable to a limited extent in the radial direction and can thereby be used to assemble the filter element 10 in the filter housing of a water separation system on an associated fuel nozzle of the filter housing are plugged in a form-fitting and fluid-tight manner. In the present case, the sealing collar is dimensioned in such a way that it can be fastened to the associated fuel connector of the filter housing in a press fit, ie with a predetermined frictional engagement.

The sieve pipe 26th is in the filter element 10 telescopic in the axial direction, ie in the direction of the longitudinal axis 18th of the filter element 10 slidably mounted in the filter element and can be removed from its in 1 Wasserabscheideposition shown in sections in connection with 2 explained maintenance item (partially) from the filter element 10 be moved out in the axial direction.

The filter element shown is the sieve tube 26th using a tongue and groove connection, for example 50 mounted axially displaceably on the central tube. This is the screen tube 26th also rotatably with the central tube 16 tied together.

The sieve pipe 26th can in its water separation position within the filter element 10 on the central tube 16 or the upper end plate 12th of the filter element 10 be kept locked. In this case, latching lugs are the first latching means on the sieve tube 52 integrally formed with the sieve tube arranged in the water separation position 26th with second locking means 54 , here snap-in recesses, of the filter element 10 cooperate. The second locking means 54 are in the embodiment shown, each on a holding web 56 the upper end disk 12th formed, which extends from the upper end disk 12th axially in the direction of the lower end plate 14th stretches away.

The lower end disk 14th of the filter element 10 has two sealing elements 58 , an outer sealing element in the radial direction 58 and a radial inner sealing element 58 , on. The two sealing elements 58 can, as shown here, each be designed as an O-ring.

In 2 is a filter system 100 for fuel with a filter element explained above 10 shown. The filter system 100 indicates an in 2 Filter housing shown only in part 102 with a fuel inlet 104 and with a fuel outlet 106 for leading the through the filter element 10 guided fuel from the filter housing 102 on.

This in 2 shown filter housing 102 is in the open state in order to exchange the filter element arranged in it 10 to enable. A cover of the filter housing 102 is in 2 not shown in detail. The sieve pipe 26th of the filter element 10 is on its terminal sealing collar to a fuel nozzle 108 the fuel outlet 106 releasably connected. The sealing collar engages around the fuel nozzle 108 in the radial direction. The flow channel arranged on the clean side 36 inside the sieve tube 26th is thus with the fuel outlet 106 fluidically connected. Inside the fuel nozzle 108 of the filter housing 102 extends a ventilation duct 110 . The ventilation duct 110 can be connected on the output side with an in 2 not shown in detail fuel tank be fluidically connected. The vent pipe 42 of the filter element 10 extends with the radial sealing element 44 into the ventilation duct 110 in a sealing manner and is fluidically connected to it.

An idle or fuel return duct of the filter housing 102 is with 112 designated. The idle channel 112 is fluidically connected on the output side to the aforementioned fuel tank and serves to divert fuel from the filter housing 102 during maintenance work, such as when replacing the filter element 10 . The idle channel 112 is in its operating position within the filter housing 102 arranged filter element 10 (not shown) through the lower end plate 14th of the filter element 10 sealed fluid-tight. The outer radial sealing element in the radial direction 58 the lower end plate 14th of the filter element 10 lies on the inside on the outside wall 114 of the filter housing 102 and the inner radial sealing element in the radial direction 58 on the radially inner wall 116 of the idle channel 112 sealing. A water outlet channel of the separator housing with an annular cross section is provided with 118 designated. The water outlet channel is in the operating position of the in the filter housing 102 arranged filter element 10 with the water separation gap 32 of the filter element 10 fluidically connected.

The sieve pipe 26th of the filter element 10 is from his in 1 shown Wasserabscheideposition, in which the sieve tube 26th completely or almost completely within the central tube 16 and the filter element 10 by pulling axially on the filter element 10 in the direction of removal 120 from his to the central tube 16 latched water separation position in the filter element 10 transferred to the telescoped maintenance position shown. The sieve pipe 26th stands in this maintenance position with a longitudinal section 122 in the axial direction over the lower end plate 14th from the filter element 10 emerged. The longitudinal section 122 in the present case corresponds to approximately half of the total length 124 of the sieve tube 26th , but can also be more than half of the total length if necessary 124 be. The sieve pipe 26th is held locked in the telescoped maintenance position shown on the central tube of the filter element (releasably), ie locked by the on the sieve tube 26th molded first locking means 52 and third locking means 60 on the central tube 16 interlock. The locking of the sieve tube 26th in its maintenance position can be made detachable to the filter element 10 to be able to return to its operating position within the filter housing. It goes without saying that the locking of the sieve tube 26th in the maintenance position in any case solely through the weight of the fuel-filled filter element 10 is not overcome. An axial force required to overcome the latching is therefore greater than the weight of the filter element filled with fuel 10 . In the maintenance position shown, the filter element 10 Contained fuel without any further action by an operator, automatically following gravity, flow downwards and out of the filter housing via the idle duct. Holding the filter element by hand 10 in his maintenance position is unnecessary. In addition, the on the fuel nozzle 108 still sealingly flanged sieve tube 26th an undesired entry of water-containing fuel and also of particulate impurities contained therein into the clean side 38 of the filter element 10 or the water separation system 100 reliably counteracted. The sieve pipe 26th has thus while the filter element is idling 10 as well as the filter housing 102 a protective function for the clean side 38 of the filter element 10 or the separation system 100 .

For complete removal of the filter element 10 from the separator housing 102 only has to go to this in the direction of removal 118 be drawn to the between the sieve tube 26th and the fuel nozzle 108 existing frictional and positive mechanical connection to loosen (overcome) and the filter element 10 completely out of the filter housing 102 move out axially. To make it easier to detach the strainer pipe from the fuel nozzle 108 can the filter element 10 additionally around the longitudinal axis 18th rotated or tilted slightly.

Claims (13)

A filter element (10) for fuel comprising: - At least one central tube (26) through which, in its operating position within the filter element (10), the fuel can flow in a direction that is radial to the longitudinal axis (18) of the filter element (10); - A connection means (48) arranged on the central pipe (26) for a releasable mechanical connection of the central pipe (26) to a filter housing (102), the central pipe (26) being mounted in the filter element (10) so as to be longitudinally displaceable and out of its operating position within the filter element (10) is displaceable in the axial direction out of the filter element (10) into a maintenance position of the filter element (10), the central tube (26) being lockable, in particular latchable, in the maintenance position relative to the filter element (10). Filter element (10) after Claim 1 , characterized in that the filter element (10) has at least one water separator for separating water contained in the fuel, which has a water outlet opening (34) for leading the water separated from the fuel out of the filter element (10) and the central pipe (26), wherein the central tube (26) is designed as a sieve tube (26). Filter element according to one of the preceding claims, characterized in that a flow channel (36) for the fuel is formed within the central tube (26) which is connected to an axial Opening (40) of the central tube (26) is fluidically connected. Filter element according to one of the preceding claims, characterized in that the connection means (48) comprises a latching element, a thread, or a bayonet locking element and / or a sealing collar, the sealing collar preferably for the fluid-tight connection of the central tube (26) to a fuel nozzle (108). of the filter housing (102) is formed. Filter element according to one of the preceding claims, characterized in that the central tube (26) can be releasably latched to the filter element (10) in its operating position within the filter element (10). Filter element according to one of the preceding claims, characterized by a central tube (16) and a coalescing medium (22) and / or a filter medium (20) for filtering out particulate impurities contained in the fuel, which is supported in the radial direction on the inside on the central tube (16) is / are. Filter element after Claim 6 , characterized in that the central tube (26), in particular the sieve tube (26), is slidably mounted on the central tube (16). Filter element after Claim 7 , characterized in that the central pipe (26), in particular the sieve pipe (26), and the central pipe (16) are coupled to one another in a rotationally fixed manner, in particular via a tongue and groove connection. Filter element after Claim 2 , in conjunction with one of the Claims 6 until 8th , characterized in that the sieve tube (26) and the central tube (16) delimit, at least in sections, a water separation gap (32) which is fluidically connected at one end to the water outlet opening (34) of the filter element (10). Filter element according to one of the Claims 2 until 9 , characterized in that the sieve tube (26) is stiffened by longitudinal and / or transverse ribs (28, 30). Filter element according to one of the Claims 2 until 10 , characterized in that the filter element (10) has a vent tube (42) which is arranged to run preferably coaxially to the longitudinal axis (18) of the filter element (10) and which in the operating position of the sieve tube (26) extends at least in sections through the sieve tube ( 26) extends through it, the vent pipe (42) having a radial sealing element (44) at one end in order to seal a vent channel (110) of the filter housing (102). Filter element after Claim 11 , characterized in that the ventilation pipe (42) is molded onto the sieve pipe (26). A filter system comprising a filter housing (102) and a filter element (10) arranged therein according to one of the preceding claims, wherein a central tube (26) of the filter element (10), in particular to a fuel connector (108) of the filter housing (102), is detachably connected.

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