EP2836283A1

EP2836283A1 - Device for filtering a thermoplastic melt

Info

Publication number: EP2836283A1
Application number: EP13712487.1A
Authority: EP
Inventors: Harald Pohl
Original assignee: Maag Pump Systems GmbH
Current assignee: Maag Automatik GmbH
Priority date: 2012-03-30
Filing date: 2013-03-22
Publication date: 2015-02-18
Also published as: JP2015518433A; WO2013152830A1; US20150014238A1; IN2014MN01831A; JP6131491B2; CN104203364B; DE102012006563B3; CN104203364A

Abstract

The invention relates to a device for filtering a thermoplastic melt, comprising a housing (1) having at least one fluid feed channel (2) and at least one fluid discharge channel (3) and having at least two bores (4, 5) which are in fluid communication with the fluid feed channel and the fluid discharge channel, respectively. In each of the bores a respective bolt (6, 7) is axially movable, radially rotatable and mounted in a fluid-tight manner, and each of the bolts is provided with a filter unit (8, 9) having an inflow side and an outflow side. The bolts can each be moved at least between a filtering position and a back-flushing position, and each of the bolts can be moved into a filling position in which via a respective clean fluid channel (12, 13) fluid flows from the outflow side of the respective filter unit to a storage space (14, 15) produced by the movement of the respective bolt in the respective bore. As the respective bore is moved into the back-flushing position the fluid again flows through the respective filter unit to the at least one back-flushing channel and out of the housing.

Description

DEVICE FOR FILTRATION OF A THERMOPLASTIC MELT

The invention relates to a device for filtering a fluid, in particular for filtering a thermoplastic polymer melt, with a housing having at least one fluid supply channel and at least one fluid discharge channel and at least two, mutually parallel and spaced bores, each with the fluid supply channel and the fluid discharge channel in fluid communication, wherein in each of the bores in each case a bolt displaced there, ie axially displaceable and / or radially rotatable, and is thereby stored fluid-tight, and each of the bolts is each provided with a Filtemest with an upstream side and a downstream side, the bolts each with at least between a first position, a Filtrierstellung, in which the respective Filemest the inlet side is in fluid communication with the fluid supply channel and the downstream side with the fluid discharge channel, and a second position, a backwash position, in which the respective filter residue is in fluid communication with the upstream side with at least one backwash channel in the housing, according to the preamble of the claim 1.

Such devices for filtering a fluid are commonly referred to in the art as screen changers. With such devices, for example, foreign particles from the fluid to be filtered, for example, from molten

Plastic filtered out in the form of its polymeric melt. Corresponding contaminants can occur, for example, in the case of molten recycled material. in the

As part of the filtration, of course, the corresponding filter or the corresponding sieve nest with residues sooner or later, so that a cleaning must be carried out. Ideally, two filter systems can be arranged parallel to each other, so that it is possible to continue running a filter system in operation, while the other is subjected to a cleaning. A cleaning can be done, for example, by so-called rewinding with already filtered fluid contrary to the usual production flow direction of the fluid. For this purpose, devices are known, which are referred to in the jargon as so-called backwash screen changer.

In particular, when employing such filter devices in applications which are very critical in terms of the mass flow of the fluid, for example in the production of

Plastic films with a small thickness, it is therefore desirable to be able to ensure a continuous flow of filtered fluid without particular fluctuations per unit time, even if a filter needs to be cleaned or replaced.

The German Utility Model DE 20 2010 017 247 Ul the applicant sees a

corresponding device for filtering a fluid, in which in a sophisticated manner different bolts are arranged in a multi-part housing. In this case, on the one hand bolts are provided which serve to receive the screens, and other bolts, which create by displacement separate cavities, which can be filled with already filtered fluid, said fluid then in a corresponding backwash position of the corresponding

Displacement bolt and the corresponding Siebträgerbolzen used for cleaning in backwashing the screen surfaces. The division there into functionally separated multiple bolt arrangements serves to maintain a constant flow of melt even in the case of a

Filter change or when rewinding to clean a single filter there.

The applicant's German patent DE 196 12 790 C2 describes a device for filtering a fluid, in which two filters are arranged in a common bolt, so that, depending on the position of the bolt, different cavities in the bolt in FIG

can be flowed through different sub-streams.

The European Patent EP 1 778 379 B1 describes an apparatus and a method for filtering a fluid, in particular for plastics processing plants, which (s) should also maintain a constant volume flow even in the case of backwashing. In this case, after a local filter test in a melt channel, an additional displacement bolt is used, which cleaned in a suitable position of the filter test

Melting in the direction opposite to the direction of production can push in the backwashing through the appropriately positioned filter there. Also there can be maintained even in the case of cleaning by the multi-part design and the division of the function on different bolts, which carry the actual filter and the displacer, a substantially continuous melt flow.

The European Patent EP 0 577 680 B1 describes a filtering device for fluids to be cleaned, in which within a piston which carries the filter there, another piston is arranged, which in the case of a required backwashing there also already filtered material in countercurrent by the local there Filter can press. Again, the functions of filtertragendem piston and additional displacer are divided according to design and executed separately.

The document WO 98/47688 describes a filter for viscose compositions, in which also already filtered fluid there by an additional displacer in a

Melting channel can be pressed back in the appropriate position through the filter in the backwash position to clean the filter there accordingly. Also, a functional separation of portafilter and displacer is structurally provided.

The present invention is therefore based on the object, an apparatus for filtering a fluid, in particular for filtering a thermoplastic polymer Melting material to provide, in which a structurally simple way a filter cleaning in backflushing is possible. In particular, according to the invention, a rewinding of the fluid can take place, which without disturbances and mass losses in the

Main flow during backwashing should work. By means of the device according to the invention, it is also to be ensured that no material can accumulate in the area of the device as much as possible so that it is there

can come.

This object according to the invention is achieved with a device for filtering a fluid having the features according to claim 1. Further preferred embodiments of the invention are defined in the subclaims.

The device according to the invention for filtering a fluid, in particular for filtering a thermoplastic polymer melt, has a housing with at least one fluid supply channel and at least one Flmdabfuhrkanal and at least two, mutually parallel and spaced holes, each with the fluid supply channel and the Fluidabfuhrkanal are in fluid communication, wherein in each of the bores in each case a bolt is axially displaceable there, radially rotatable and thereby stored fluid-tight, and each of the bolts is each provided with a Filtemest with an upstream side and a downstream side, the bolts each at least between a first Position, a Filtrierstellung in which the respective Filtemest is in fluid communication with the upstream side with the fluid supply channel and with the downstream side with the fluid discharge channel, and a second position, a backwash position, in which the respective Filememest the inflow side is in fluid communication with at least one backwash passage in the housing, are displaceable. In this case, according to the invention, each of the bolts in a third position, a filling, displaced, in which flows via a respective clean fluid passage in the respective bolt fluid from the downstream side of the respective filter test to a resulting by the displacement of the respective bolt in the respective bore storage cavity, which then upon displacement of the respective bolt in the second position again flows through the respective screen nest to at least one backwashing and thus exits the housing. During the entire corresponding displacement movement of the bolt according to the invention during "pulling on" (third position) and "pushing through" (second position), the creation or enlargement and filling with fluid of the storage cavity (altogether referred to as third position) or the reduction respectively Finally, the disappearance and the back pressure of the fluid of the storage cavity (collectively referred to as the second position) while the bolt is displaced axially back and forth, similar to a syringe.

Thus, therefore, with the device according to the invention the function of creating a cavity for receiving already cleaned fluid from the production in a component be combined with the corresponding possible backwashing by the displacement of the bolt through which the previously collected fluid can be backwashed through the corresponding filter in the same bolt. By corresponding provision of two parallel bolt arrangements provided in addition, the continuous mass management of purified fluid during the production process of an entire system - gewähr.-Contrary to the prior art, it is therefore not according to the invention

required to have to provide a separate displacer, which separate

In addition, relocation mechanisms would require. Rather, simply the bolt, which also receives the screen surface, at the same time providing the appropriate volume for receiving purified fluid and the displacement of this fluid in

Backwash during backwashing through the screen surface accordingly allow in a single arrangement with only one bolt and only one each correspondingly assigned actuator. This results in a particularly simple construction, which is also compact and space-saving integrated into larger total production plants.

In the sense of the device according to the invention described and claimed, the terms "positions" are thus to be understood in terms of variable position with respect to the pin position, which in itself includes a displacement of the respective bolt and not limited to static "end points" of corresponding movements to be understood. This applies in particular to the second and the third position, which in itself comprises a corresponding inventive pin displacement for creating and filling or for reducing and expressing the fluid in / from the storage cavity in the filling or backwashing.

According to a preferred embodiment of the device according to the invention, in the first position of the respective bolt, the downstream side of the respective filter test on the respective clean fluid channel, a respective radially arranged on the respective bolt and only partially over the circumference of the one end face of the respective bolt extending radial groove and a respective axially extending longitudinal groove of the respective bolt to be connected to the at least one Fluidabführkanal.

By inventively preferred provision of the radial or the corresponding longitudinal groove in each case a permanent flow with fluid in the first position of the bolt according to the invention particularly reliable possible. Thus, it does not cause clogging with any melt that may otherwise settle in dead spaces and solidify.

According to the invention, the respective longitudinal groove preferably extends over only an axial partial length of the respective bolt. Preferred is an embodiment of the device according to the invention, wherein the respective radial groove is covered at the one end face of the respective bolt there by a respective cover plate, wherein the respective cover plate has a therethrough extending respective passage opening, so that a fluid connection between the respective radial groove and the respective storage cavity during the displacement movement of the bolt, in particular during axial displacement of the bolt forward or backward exists.

Even with the cover plate provided according to the invention, it is achieved that there the fluid does not settle during filling and without tendency to solidify in

Backwash can also be backwashed again.

Further preferred is an embodiment of the device according to the invention, wherein formed by an axial displacement of the respective bolt from the first position to the third position at the respective end face of the respective storage cavity for filtered fluid and wherein over the entire distance of the axial displacement of the respective downstream side the respective filter test on the respective clean fluid channel, the respective radial groove and the respective longitudinal groove is connected to the at least one fluid discharge channel.

With this erfindungs gemä preferred design, the continuous appropriate flow with fluid is particularly reliable, so that a solidification of fluid in otherwise possibly occurring cavities or dead spaces is not to be feared.

Femer preferred is an embodiment of the device according to the invention, wherein the respective bolt from the first position by radial rotation in a first intermediate position can be transferred and wherein depending on the size of the rotation angle of the fluid discharge channel through the wall of the respective bolt is partially or completely closed, so that with complete closure, the respective axially extending longitudinal groove of the respective bolt is no longer connected to the at least one fluid discharge channel.

Also preferred is an embodiment of the device according to the invention, wherein in a second intermediate position of the respective bolt depending on the size of the angle of rotation of the fluid supply passage through the wall of the respective bolt is partially or completely closed, so that at full closure the upstream side of the respective filter nest of the respective bolt is no longer connected to the at least one fluid supply channel.

Through the appropriate use of the lateral surface of the bolt for sealing corresponding openings in the housing is in a structurally particularly simple way the

Melting guide in the filter device according to the invention allows. In particular, can As a result, the corresponding bolts are kept very compact in size, without the need for additional expensive valves or seal arrangements are required.

Advantageously, according to the invention, the respective pin may preferably be displaceable in such a way that it is located both in the second position and in the first intermediate position at the same time.

Furthermore, according to the invention, the respective bolt may advantageously be displaceable in such a way that it is located both in the third position and in the second intermediate position at the same time.

Likewise, the respective bolt may expediently be displaceable according to the invention such that it is located both in the first and second intermediate positions and / or in the second and third positions at the same time.

The seal by the bolt itself can thus be provided in a particularly effective and structurally simple manner by abutment of the bolt lateral surface for sealing the corresponding openings of the housing.

In accordance with a further preferred embodiment of the device according to the invention, at least one backwashing channel is assigned to each filter residue.

By providing several holes and backwash channels, the continuous

Mass flow can be particularly easily realized during the backwashing of one of the sieves in one of the bolts.

According to the invention, the respective bolt can have a respective discharge channel, which in a fourth position, a starting position, of the respective bolt can be brought into fluid communication with the fluid supply channel and has an opening to the environment of the device, so that thereby fluid can be discharged from the device.

The housing of the device according to the invention may be preferably in one or more parts, for example in two parts, each housing part each having one of the holes, each having a fluid supply channel and a Fluidabfuhrkanal and one of the bolts, each with a filter residue, each having a backwash channel and a respective discharge channel.

According to a further preferred embodiment of the device according to the invention, the respective bolt can be displaced into a fifth position, a screen change position, in which the respective one filter nest is located outside the housing, so that the respective one Filtemest is interchangeable in this position, wherein the fifth position is in the direction opposite to the end face of the respective bolt.

Thus, in the fifth position, this can easily be done in the case of a required screen change, without the entire device would have to be completely disassembled. In particular, it is not necessary that the screen changing the sealing end face of the

corresponding bolt must be completely removed from the bore of the housing.

However, under certain spatial circumstances, it may also make sense to have a screen change on the front side, if the installation space on the end of the filter device facing away from the end should not be sufficient there for changing the filter. Then, the fifth position can be realized with a removable on the front side after removal of a cover plate out there bolt.

In this case, the respective pin may particularly preferably be so long and displaceable that in the fifth position the at least one fluid supply channel and the at least one fluid discharge channel are completely closed by the wall of the respective pin.

According to a preferred embodiment of the device according to the invention, respective shut-off valves may be provided in front of the at least one fluid supply channel and after the at least one fluid discharge channel, by means of which the respective channels can be locked in the fifth position of the respective pin.

Suitably as simple as possible according to the invention may be the design of the respective bolt such that the starting position of the respective bolt, that is the fourth position described above, the fifth position described above, the screen change position corresponds.

If you want to build the bolt as compact as possible, so that no sealing bolt surfaces in the case of a screen change can cover the corresponding openings in the housing, so can be done with the embodiment using said shut-off still structurally relatively simple blocking the melt flow. In the axial

Extension, the bolt can thus be designed shorter, which under certain

spatial conditions of an entire system can be beneficial.

The device comprises according to a preferred embodiment of the invention, two bolts which are mounted independently of each other between the first position, the second position, the third position, the fourth position, the fifth position and the first and second intermediate position movable through corresponding holes in the housing In the first position, the respective bolt filters the fluid to be filtered and, in the second position of the bolt, the filter residue of this bolt is not supplied with fluid to be filtered and opposite to the filtering direction of filtered fluid coming from the said bolt is supplied through the associated storage cavity, is flowed through that filled during filtration by the respective other bolt of the respective one bolt associated storage cavity by axial displacement of the respective one bolt from the first position to the third position or in the third and at the same intermediate position with filtered fluid is and that at least a portion of the thus stored fluid is then supplied by the displacement of the respective one bolt to the respective Filtemest the respective one bolt, if the respective one bolt from the third position or the third position and at the same time second intermediate position in the second position or the second position and at the same time first intermediate position is transferred. In alternation, the operation of the entire system can therefore take place continuously by correspondingly intermittent movements of the respective bolts.

In the manner described, a continuous production operation is thus possible in a structurally simple manner without major fluctuations in the mass flow of the filtered melt, at the same time the corresponding backwashing purification of individual

Filter elements can be done.

The invention will be described below by way of example only and not shown

Embodiments limiting be explained in more detail. In the figures shows:

1 is a top perspective view of a filtration apparatus according to a first preferred embodiment of the invention;

Fig. 2 is a schematic, partially sectioned view of a detail of a device

according to the preferred embodiment of the invention according to FIG. 1;

Fig. 3 is a perspective top view of a device for filtering according to a

second preferred embodiment of the invention;

Fig. 4 is a schematic, partially sectioned view of a detail of a device

according to the preferred embodiment of the invention according to FIG. 3;

5 is a schematic, sectional view of a detail of a device according to another preferred embodiment of the present invention;

FIG. 6 is a cross-sectional view according to a preferred embodiment of the invention shown in FIG. 5; FIG.

Fig. 7a, 7a 'to 7g, 7g' respectively show schematically partially sectioned views of

Device according to the invention in view of the outlet side of a melt or in view of the inlet side of a melt seen in different

Operating conditions; and

8a, 8a 'show a further preferred embodiment of the present invention in a schematic, partially sectioned view from the outlet side or from the inlet side. In the figures, the same elements are denoted by the same reference numerals, wherein in some figures, the reference numerals are omitted for reasons of clarity. The individual described elements according to the preferred embodiments of the present invention

The invention can be combined as desired with one another for the skilled worker, with the embodiments shown not being restricted to the respective combinations.

Figure 1 is a perspective plan view of an apparatus for filtering a fluid according to a first preferred embodiment of the present invention. The apparatus shown serves in particular for filtering a thermoplastic polymer melt and has a housing 1 with bolts 6, 7, which there in bores 4, 5 (upper bore 4 in Fig. 1 not seen) in the housing 1 extending movable, d , H. axially displaceable or radially rotatably mounted fluid-tight. Each of the bolts 6, 7 has in each case at least one filter nest 8, 9 (upper filter nest 8 not visible in FIG. 1), with an inflow side and a downstream side. In Fig. 1, the lower bolt 7 in a fifth position, a

Screen change position, shown. In this case, according to the embodiment of the device according to the invention shown in Fig. 1, the respective bolt on the arranged on the opposite side actuators 26, 27 on the front side of the housing 1 after removal of a

Cover plate, which is still shown for the upper bolt and attached to the housing (attached cover plate 28), moved out of the housing, so that a screen change can be made there endseitig.

Fig. 2 shows in a schematic sectional view of a detail of the device according to the invention shown in FIG. 1, a lower pin 7 in the filter change position in the direction of the actuator side away on the front side of the housing moved out in the fifth position, the screen change position. According to the representation of FIG. 2, the upper pin 6 shown there is in a second position, namely in a backwash position. Fig. 2 also shows a discharge channel 29 at least of the lower pin 7, via which in the position shown it can be brought into fluid communication with the fluid supply channel 2 and has an opening to the environment of the device, thereby for example unsuitable fluid, e.g. when starting from the device can be discharged. The corresponding discharge channel of the upper bolt 6 can not be seen through the rotated position of the bolt 6 in FIG.

FIG. 3 shows in a perspective plan view a device for filtering a fluid according to a second preferred embodiment of the invention. In this case, according to the embodiment of the device according to the invention shown in FIG. 3, in contrast to the embodiment of the invention shown in FIG. 1, the respective pin 6, 7 can be moved out of the housing 1 in the direction of the respective actuator 26, 27 in the screen changing position. According to the representation of FIG. 3, therefore, the device according to the invention shown there is designed such that there the filter change position corresponding to the position 5 is not end-side takes place, but by pulling the corresponding pin 7 in the direction of the actuator 27th

The actuators 26, 27 shown in FIGS. 1 and 3 for displacing the respective bolts 6, 7 are preferably hydraulic cylinders, which are connected via corresponding linkages with the respective bolt according to the invention and the described bolt displacements in the axial and radial directions with corresponding displacements and rotational movements

This is not explained in more detail since the basic use of such hydraulic cylinders is familiar to the person skilled in the art.

FIG. 4 shows in a schematic sectional view of a detail of the device according to the invention according to FIG. 3 a lower pin 7 in filter change position in the direction of the actuator side moved out of the housing. The bolt 6 as well as the bolt 7 have a length in the axial direction, which makes it possible that by the bolt wall, the respective bore of the fluid supply channel 2 (as well as the Fluidabfuhrkanals 3 (not visible in Figures 1 to 5)) sealed is when the corresponding bolt is in the fifth position, the Siebwechselstellung. According to the representation of FIG. 4, the upper pin 6 shown there is in a first position, namely in an operating position.

The representation of FIG. 5 differs from the representation of FIG. 4 only in that the local pins 6 and 7 are each made shorter, so that through the

Bolt wall no fluid-tight seal of the fluid supply channel 2 and des

Fluid discharge channel 3 is possible. According to the embodiment shown in Fig. 5, therefore, the use of additional sealing elements is necessary.

Such sealing elements are shown schematically in a sectional view according to FIG. 6. Fig. 6 shows a cross-sectional view of a housing 1 with the therein

Holes 4, 5, in which the bolts 6, 7 are axially displaceable, radially rotatable and thereby stored fluid-tight. However, the bolts are not shown in FIG. 5. Thus, in the case of the filter change, d. H. In the event that one or both bolts are in the fifth position, the fluid flow can be interrupted, in each case designed as a rotary slide valves shut-off valves 24, 25 are provided in front of the fluid supply channel 2 and the fluid discharge channel 3. By means of these shut-off valves 24, 25, the respective channel 2, 3 can be lockable in the fifth position of the respective bolt.

In FIGS. 7a, 7a 'to 7g, 7g', the position of one of the bolts 6, 7 is shown schematically from a fluid outlet side (FIGS. 7a to 7g) or from a fluid inlet side (FIGS. 7a 'to 7g') in the housing 1 according to a preferred embodiment of the invention. In FIGS. 7a, 7a 'to 7g, 7g', the device according to the invention for filtering a fluid is shown, which can be used in particular for filtering a thermoplastic polymer melt. In the housing, each with spaced holes 4, 5 is a respective fluid supply channel 2 and a respective fluid discharge channel 3 associated with the respective mutually parallel bores and standing in fluid communication with these bores. The housing 1 is made in one piece according to the embodiment shown. However, it is also possible in principle that each of the housing parts is designed individually with a respective bore and realized in a multi-part housing accordingly. In each of the bores 4, 5 is in each case a bolt 6, 7 there axially displaceable, radially rotatable and thereby stored fluid-tight. The bolt movement can over the

Actuators 26, 27 (see, for example, Fig. 1 or Fig. 3) take place. Each of the bolts 6, 7 has in each case a filter residue 8, 9 with an inflow side, from which fluid to be filtered flows, and with a downstream side, from which the filtered fluid flows off after the filter test. As shown in FIGS. 7 a, 7 a ', the lower bolt 7 is in a first position, a filtering position, in which the filter nest 9 is in fluid communication with the inflow side with the fluid channel 2 and with the downstream side with the fluid channel 3. 7a, 7a ', the upper pin 6 is in an end position of a second position, a backwash position, in which the filter nest 8 of the upper pin 6 is in fluid communication with the upstream side thereof with an associated backwash channel 10. As shown, the backwashing process is already completed.

Fig. 7b, 7b 'shows both bolts 6, 7 respectively in the first position, the filtration position, wherein the downstream side of the respective filter modules 8, 9 of the respective bolt on respective

Pure fluid channels 12, 13, a respective end side arranged on the respective pin 6, 7 and extending only partially over the circumference of one end face of the respective bolt

Radialnut 16, 17 and a respective axially extending longitudinal groove 18, 19 of the respective bolt 6, 7 is connected to the respective fluid discharge channel 3. According to the embodiment of the device according to the invention shown in the figures of the sequence of FIG. 7, the respective radial groove 16, 17 at the respective end face of the respective bolt 6, 7 covered there by a respective cover plate 20, 21, wherein the respective cover plate 20, 21 has a respective passage opening 22, 23 extending therethrough. About these

Through hole can in a later shown third position of the respective bolt 6, 7, a fluid connection between the respective radial grooves and a respective

Reservoir cavity 14, 16 formed by the bolt movements in the third position exist.

7, 7c, 7c ', the upper pin 6 is transferred by radial rotation from the first position to a first intermediate position, so that depending on the size of the angle of rotation of the associated fluid discharge channel 3 through the wall the bolt 6 partially, or as in the case shown in FIG. 7c, 7c 'completely closed. Thus, in this complete closure is the axially extending longitudinal groove 18 of the bolt 6 is no longer in fluid communication with the

Fluid removal channel 3 of this bolt.

As shown in FIGS. 7d, 7d ', the bolt 6 is in an axial displacement movement in a third position, a filling position, in which via the clean fluid channel 12 of the bolt 6, the fluid from the downstream side of the filter 8 to a test by the displacement of the bolt 6 in the bore 3 resulting supply cavity 14 flows (the corresponding

Storage cavity 15 of the lower bolt 6 is not shown in the figures). The movement of the bolt 6 is shown by the arrow in the figure.

In general, the states of movement of the bolts 6, 7 are visualized in the figures by corresponding arrows.

According to the position of the upper bolt 6 shown in Figs. 7e, 7e ', the filling operation, which has taken place in accordance with the movement in the third position of this bolt 6, is completed, and the resulting storage cavity 14 is filled with fluid from the downstream side of the filter test 8 filled. According to the representation of FIGS. 7e, 7e ', the bolt 6 is in a second

Twisted position in which the bolt 6 depends on the size of the

Rotary angle with its wall, the fluid supply channel 2 partially or completely (according to the illustration of Fig. 7e, 7e 'completely) closes, so that the inflow side of

Filtemests 8 of the bolt 6 is no longer connected to the associated fluid supply channel 2. Now, according to the backwashing of the filter test 8 of the bolt 6 done. If one looks at the illustration according to FIGS. 7f, 7f, it can be seen there that by renewed

Return displacement of the bolt 6 in the bore 4, the fluid from the storage cavity 14 is again pressed to the downstream side of the filter test 8 and through the filter nest 8 to the upstream side and thereby flows to the pin 6 associated with this backwash 10 and can escape from the housing 1. The bolt 6 is in a second position, a backwash position, in which the filter nest 8 is in fluid communication with at least the backwash channel 10 with the upstream side and wherein the bolt 6 is further displaced axially accordingly.

7g, 7g 'now shows the end of the movement of the bolt 6 in the second position, wherein, as shown in FIG. 7g, 7g' indicated that the fluid connection between the upstream side of the filter 8 and the associated backwash 10 in Fluid connection is when the corresponding bolt moves back already in the direction of the first position.

The representation of FIGS. 8a, 8a ', similar to the sequence according to FIGS. 7a, 7a' to 7g, 7g ', schematically shows an embodiment of the device according to the invention, wherein the embodiment according to FIGS. 8a, 8a' of the embodiment according to the sequential Representation of FIG. 7 differs in that in Fig. 8a, 8a 'each no Cover plates 20, 21 are provided which cover the respective radial groove 16, 17 on the end face of the respective bolt 6, 7.

With the device according to the invention it is possible, using the respective bolt, which carries the respective filter test itself, d. H. only with appropriate movement of this bolt to recover backwash fluid, which can then be backwashed by the bolt movement itself again through the respective filter test of the corresponding bolt.

Elaborate solutions which work according to the prior art here with several additional bolts and additional fluid connections are therefore not required according to the invention. The inventive device can thus constructively simple and space-saving allow a reliable backwashing and thus cleaning of the corresponding filter device. With the device according to the invention can thus be realized according to the invention in a simple manner constructive without high construction costs, a reliable in operation and yet easy to operate and fast to be cleaned by backwashing filter device.

Claims

claims

1. Apparatus for filtering a fluid, in particular for filtering a thermoplastic polymer melt, comprising a housing (1) with at least one fluid supply channel (2) and with at least one fluid discharge channel (3) and with at least two, mutually parallel and spaced bores (4, 5), which in each case in fluid communication with the fluid supply channel (2) and the fluid discharge channel (3), wherein in each of the bores (4, 5) each have a bolt (6, 7) axially displaceable there, radially rotatable and thereby each of the bolts (6, 7) is provided with a respective filter residue (8, 9) with an inflow side and a downstream side, the bolts (6, 7) each at least between a first position, a filtration position, in in which the respective filter residue (8, 9) is in fluid communication with the inflow side with the fluid supply channel (2) and with the downstream side with the fluid discharge channel (3), and a second position, a return rinsing position, in which the respective filter residue (8, 9) with the upstream side with at least one backwash duct (10, 11) in the housing (1) is in fluid communication, are displaced, characterized in that

each of the bolts (6, 7) is displaceable into a third position, a filling position, in which fluid from the downstream side of the respective filter test (8, 9) is conveyed via a respective clean fluid channel (12, 13) in the respective bolt (6, 7) to a by the displacement of the respective bolt (6, 7) in the respective bore (4, 5) resulting supply cavity (14, 15) flows, which then on displacement of the respective bolt (6, 7) in the second position again through the respective Siebnest (8, 9) to at least one backwash duct (10, 11) flows and thus emerges from the housing (1).

2. Apparatus according to claim 1, characterized in that in the first position of the respective bolt (6, 7) the downstream side of the respective filter test (8, 9) via the respective clean fluid channel (12, 13), a respective, end face on the respective bolt (6, 7) and only partially over the circumference of the one end face of the respective bolt (6, 7) extending radial groove (16, 17) and a respective axially extending longitudinal groove (18, 19) of the respective bolt (6, 7 ) is connected to the at least one fluid discharge channel (3).

3. A device according to claim 2, characterized in that the respective radial groove (16, 17) on the one end face of the respective bolt (6, 7) is covered there by a respective cover plate (20, 21), wherein the respective cover plate (20 , 21) has a respective passage opening (22, 23) extending therethrough, so that a fluid connection between the respective radial groove (16, 17) and the respective storage cavity (14, 15) in the third position.

4. Device according to one of the preceding claims, characterized in that by an axial displacement of the respective bolt (6, 7) from the first position to the third position at the respective end face thereof the respective storage cavity (14, 15) for filtered fluid Forms and that over the entire distance of the axial displacement of the respective downstream side of the respective filter test (8, 9) via the respective clean fluid passage (12, 13), the respective radial groove (16, 17) and the respective longitudinal groove (18, 19) with the at least one fluid discharge channel (3) is connected.

5. Device according to one of the preceding claims, characterized in that the respective pin (6, 7) from the first position by radial rotation in a first intermediate position can be transferred and that depending on the size of the angle of rotation of the fluid discharge channel (3) through the Wall of the respective bolt (6, 7) is partially or completely closed, so that with complete closure, the respective axially extending longitudinal groove (18, 19) of the respective bolt (6, 7) no longer connected to the at least one fluid discharge channel (3) is.

6. Device according to one of the preceding claims, characterized in that in a second intermediate position of the respective bolt (6, 7) depending on the size of the angle of rotation of the fluid supply channel (2) through the wall of the respective bolt (6, 7) partially or is completely closed, so that with complete closure, the inflow side of the respective filter residue (8, 9) of the respective bolt (6, 7) is no longer connected to the at least one fluid supply channel (2).

7. The device according to claim 5 or 6, characterized in that the respective pin (6, 7) is displaceable so that it is simultaneously in both the second position and in the first intermediate position.

8. Apparatus according to claim 5 or 6, characterized in that the respective pin (6, 7) is displaceable so that it is located both in the third position and in the second intermediate position at the same time.

9. Device according to one of the preceding claims, characterized in that the respective longitudinal groove (18, 19) only over an axial partial length of the respective bolt (6, 7).

10. Device according to one of the preceding claims, characterized in that each filter residue (8, 9) at least one backwash channel (10, 11) is associated.

11. Device according to one of the preceding claims, characterized in that the respective pin (6, 7) has a respective discharge channel (29), which in a fourth position, a starting position, of the respective bolt with the fluid supply channel (2) in fluid communication can be brought is and has an opening to the environment of the device, so that thereby fluid can be discharged from the device.

12. Device according to one of the preceding claims, characterized in that the housing (1) is multi-part, preferably in two parts, each housing part in each case one of the bores (4, 5), in each case a fluid supply channel (2) and a fluid discharge channel (3). and in each case one of the bolts (6, 7), each having a filter residue (8, 9), in each case a backwashing channel (10, 11) and in each case a discharge channel.

13. Device according to one of the preceding claims, characterized in that the respective pin (6, 7) in a fifth position, a screen change position, is displaceable, in which each a filter nest (8, 9) outside the housing (1) itself is located so that the respective Filtemest (8, 9) is interchangeable in this position, wherein the fifth position in the direction opposite to the end face of the respective bolt (6, 7) is located.

14. Device according to one of the preceding claims, characterized in that the respective pin (6, 7) is so long and so displaceable that in the fifth position, the at least one fluid supply channel (2) and the at least one fluid discharge channel (3) through the Wall of the respective bolt (6, 7) is completely closed.

15. Device according to one of the preceding claims, characterized in that respective shut-off valves (24, 25) are provided in front of the at least one fluid supply channel (2) and after the at least one fluid discharge channel (3) by means of which in the fifth position of the respective bolt ( 6, 7) the respective channels are lockable.

16. Device according to one of the preceding claims, characterized in that the device comprises two bolts (6,7) independently of one another between the first position, the second position, the third position, the fourth position, the fifth position and the first and second intermediate position are movably supported by corresponding bores in the housing, wherein in the first position of the respective bolt (6, 7) the filtered fluid to be filtered and in the second position of the bolt (6, 7) the filter test (8, 9) this Bolzens (6, 7) is not flown with fluid to be filtered and opposite to the direction of filtration of filtered fluid, which is supplied from the said bolt (6, 7) associated storage cavity (14, 15) is flowed through that during filtration through the respective other bolts (6, 7) of the respective one bolt (6, 7) associated storage cavity (14, 15) by axial displacement of the respective one bolt (6, 7) the first position in the third position or in the third and at the same intermediate position is filled with filtered fluid and that at least a part of the fluid thus stored is then supplied by the displacement of the respective one bolt (6, 7) to the respective filter residue (8, 9) of the respective one bolt (6, 7), if the respective one bolt (6, FIG. 7) from the third position or the third position and at the same time the second intermediate position in the second position or the second position and at the same time the first intermediate position is transferred.