Filtration device for filtering fluids and related methods of operation
Patent Information
- Application Number
- JP2024555221
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-03-18
- Filing Date
- 2023-03-20
- Publication Date
- 2026-03-23
Smart Images
Figure 00000000_0000_ABST
Abstract
Description
[Technical field]
[0001] The present disclosure relates to a filtration device for filtering fluids, particularly liquid plastics, comprising a receptacle for receiving a screen carrier, a housing having a fluid inlet channel and a fluid outlet channel, and a screen carrier movably received within the receptacle along a longitudinal axis, the screen carrier having a screen carrier inlet, a screen carrier outlet, and a cavity for receiving a filter element, the cavity being in fluid communication with the screen carrier inlet and the screen carrier outlet, and the screen carrier can be moved from a screen replacement position to a filtering position via a venting (degassing) position area.
[0002] [Citation to Related Applications] This application is a national stage application of International Application No. PCT / PCTIB2023052726, filed March 20, 2023, which claims priority from German Patent Application No. 10 2022 106 334.8, filed March 18, 2022, and which designates the United States, the entire contents of which are incorporated herein by reference. [Background technology]
[0003] Filtration devices are used in plastic processing machines, for example when the purity of the plastics being processed has to meet strict requirements. These plastic processing machines are typically arranged between an extruder, which melts and conveys the plastic, and an applicator. Such filtration devices for filtering fluids, in particular liquid plastics, as well as methods for their operation are known in the prior art. For example, DE 10 2007 057 861 A1 describes such a filtration device having a screen carrier or support, which houses filter elements (also called screens).
[0004] Such filter elements typically have to be replaced or cleaned if they have been in operation for some time. To replace the filter element, the screen carrier can be moved from a filtering position, also called a production position, to a so-called screen change position, in which the filter element can be accessed and replaced.
[0005] Once the filter element has been replaced, it must be returned to the production process. This creates the following problem: the internal space of the screen carrier, called the cavity, is typically filled with air after the screen replacement, and it is essential to prevent air from being introduced into the plastic fluid stream (steady flow). That is why, after the screen replacement, the screen carrier is first moved into the ventilation position area, where the liquid plastic flows into the screen cavity and expels the air contained therein to the outside via the ventilation channels.
[0006] Once the cavity is completely filled or vented, the liquid plastic must be moved again in order to begin the filtration process. This is because the plastic melt has a certain amount of inertia, which can result in undesirable pressure fluctuations throughout the system if the melt is accelerated. Thus, there has been a challenge in accelerating the melt after it has stopped moving so that the overall system pressure remains within narrow, definable limits.
[0007] This aspect also plays a role during backflushing of the filter element, where the filter element is backflushed with plastic melt in the opposite direction to the filtration position to clean the filter element. The plastic used for backflushing is taken from the plastic fluid stream to be filtered. If the plastic fluid stream is backflushed too quickly, this may also have a negative effect on the system pressure. For example, when using spinning nozzles, such pressure fluctuations may have a negative effect on the spinning process. Product quality may be compromised or even the spun plastic may break.
[0008] Methods for controlling plastic processing systems are known from the prior art, for example from DE 10 2006 019 445 A1, which proposes to equalize pressure variations by adjusting the feed rate of the conveying device. A disadvantage of this prior art document is that there is an adjustment delay between the drop in system pressure caused by filling the cavity and the adjustment of the pump power. As a result, pressure variations cannot be eliminated with sufficient reliability.
[0009] This approach of controlling pump output according to screen replacement operations also contributes to an increase in the complexity of the system, thus increasing production costs and the maintenance required for such machines. [Prior art documents] [Patent documents]
[0010] [Patent Document 1] DE 10 2006 019 445 A1 Summary of the Invention
[0011] In view of this technical background, one aspect of the present disclosure is to develop an improved apparatus and method of the type described at the beginning so as to eliminate as far as possible the drawbacks identified in the prior art. A particular aspect of the present disclosure is to provide an apparatus and method which keeps the overall system pressure approximately constant during a screen replacement operation or backflushing of a filter element, while reducing the overall complexity of the system.
[0012] According to the present disclosure, this aspect is achieved by a filtering device of the type described at the beginning, characterized in that the screen carrier has a throttle recess arranged adjacent to the screen carrier outlet and in fluid communication with the cavity, the throttle recess opening a variable flow cross-section between the cavity and the fluid outlet channel depending on the position of the throttle recess relative to the fluid outlet channel.
[0013] The present disclosure takes advantage of the discovery that by locating the throttle recess adjacent to the screen carrier outlet, a particularly fine adjustment of the free flow cross section between the outlet channel and the cavity is possible. In this way, once the cavity is fully vented via the throttle recess, the cavity can be connected to the fluid outlet channel in such a way that the melt can be gently accelerated out of the cavity in the direction of the fluid outlet channel. In other words, the melt received in this way in the fluid inlet channel and in the cavity can be controlled and moved slowly in such a way that the overall system pressure is substantially unaffected by the acceleration action and is kept at least within acceptable limits.
[0014] According to one aspect, the screen carrier can be moved from a vent position region through an acceleration position region to a filtering position, the throttle recess opening a variable flow cross section between the cavity and the fluid outlet channel depending on the position of the throttle recess relative to the fluid outlet channel in the acceleration position region. The acceleration position may be spaced from the vent position region such that the melt does not accelerate until it has passed through the vent position region, i.e. until the cavity is fully vented.
[0015] Due to the acceleration location regions according to the present disclosure, initially flow channels may be formed / provided by recesses or grooves, which help and are used to get the melt moving again after a functional stop, particularly after a screen change, i.e., to accelerate the overall flow, and this may be done so gently so that large pressure fluctuations and / or large scale turbulence do not occur within the filtration device, but can almost be present in the system, and / or no mixing of the melt and gas (sometimes also referred to as foaming) occurs.
[0016] The present disclosure is improved by developing the throttle recess starting from the screen carrier outlet and extending along the longitudinal axis, seen from the screen exchange position, in the direction of the fluid outlet channel. Thus, a variable flow cross section between the cavity and the fluid outlet channel is opened and / or adjusted by moving the throttle recess in the direction of the fluid outlet channel by moving the screen carrier. In other words, by changing the position of the screen carrier along the longitudinal axis, it is possible to affect the flow cross section between the cavity and the fluid outlet channel as desired.
[0017] According to one aspect, the throttle recess has a cross section that changes in the direction of the longitudinal axis. The cross section of the throttle recess can taper in the direction of the longitudinal axis, starting from the screen carrier outlet. Thus, as a result of any movement of the screen carrier and thus of the throttle recess in the direction of the fluid outlet channel, only a very small cross section is initially opened between the cavity and the fluid outlet channel, and the flow cross section increases disproportionately when the screen carrier is further advanced. In this way, the system pressure can be advantageously influenced and the melt can be accelerated.
[0018] The cross section of the throttle recess can taper linearly starting from the screen carrier outlet in the direction of the longitudinal axis. According to one aspect, this cross section has a basic form in the form of a wedge or a notch, which allows a particularly fine adjustment of the flow cross section.
[0019] According to one aspect, the fluid inlet channel and the fluid outlet channel are arranged in the housing in such a way that when the screen carrier moves from the screen exchange position through the venting position area and the acceleration position area in the direction of the filtering position, the cavity in the venting position area is initially, in particular exclusively, in fluid communication with the fluid inlet channel, and when the screen carrier moves further in the direction of the filtering position, the cavity in the acceleration position area is further placed in fluid communication with the fluid outlet channel through the throttle recess. As a result, the cavity is filled particularly gently in terms of the overall system pressure. By connecting the fluid inlet channel to the cavity, the fluid inlet is initially vented. In this position, no connection to the fluid outlet channel occurs so far. The situation where a very small cross section is initially opened to the fluid outlet channel does not occur until the screen carrier is moved further in the direction of the filtering position through the throttle recess, as a result of which, as described above, the melt in the cavity is accelerated particularly gently, which in particular results in a constant overall system pressure as described above. Furthermore, if the connection to the outlet channel already occurs when the cavity is vented, air bubbles may be forced in during the production process, which is undesirable.
[0020] According to one aspect, the screen carrier, located adjacent to the screen carrier inlet, has an inlet throttle recess in fluid communication with the cavity, which opens a variable flow cross-section between the cavity and the fluid inlet channel depending on the position of the inlet throttle recess relative to the fluid inlet channel in the vent position area, in this way the melt is delivered to the cavity particularly gently and delicately even when the cavity is vented by the inlet throttle recess, whereby pressure fluctuations relative to the overall system pressure are again avoided as far as possible.
[0021] The inlet throttle recess can start from the screen carrier inlet and extend along the longitudinal axis, seen from the screen change position, in the direction of the fluid inlet channel, so that the cavity is first connected to the fluid outlet channel via the inlet throttle recess, which allows the cavity to be flooded in a particularly delicate manner. The inlet throttle recess can have a cross section that changes in the direction of the longitudinal axis. It has been found that such a design of the inlet throttle recess is advantageous, since the cavity can be filled particularly gently with respect to the overall system pressure.
[0022] The present disclosure is quantitatively developed by the fact that the screen carrier has at least one ventilation recess which places the cavity in fluid communication with the surroundings depending on the position of the ventilation recess relative to the housing. Such ventilation recesses are a proven technology which influence the ventilation work not only on the inlet side, i.e. near the fluid inlet channel, but also in the outlet area. The ventilation recess may extend along the longitudinal axis. This means that the cross section available for the evacuation of air can be varied depending on the positioning of the screen carrier and thus of the ventilation recess relative to the housing.
[0023] According to one aspect, the ventilation recess is a first ventilation recess and the screen carrier has a second ventilation recess in fluid communication with the cavity, the second ventilation recess having a shorter longitudinal extension along the longitudinal axis than the first ventilation recess and arranged in such a way that when the screen carrier moves from the screen changing position towards the filtering position, the cavity is first vented via the first and second ventilation recesses and when the clean carrier moves further towards the filtering position, the cavity is vented only via the first ventilation recess. The ventilation recess may have a third ventilation recess, the third ventilation recess having a shorter longitudinal extension along the longitudinal axis than the second ventilation recess.
[0024] According to one aspect, the first ventilation recess is in fluid communication with a first sub-region of the cavity and / or the second ventilation recess is in fluid communication with a second sub-region of the cavity and / or the third ventilation recess is in fluid communication with a third sub-region of the cavity, thereby allowing for ventilation in a targeted manner of individual sub-regions of the cavity as well as ventilation of the entire cavity to be affected.
[0025] When the screen carrier moves from the screen changing position towards the filtering position, the screen carrier in the ventilation position may initially be vented via all three ventilation recesses, although more than four, in particular four, ventilation recesses may be provided. Initially, all, in particular all three, ventilation recesses may be connected to the periphery of the filtering device. The melt then typically exits from the medium length ventilation recess. Then, after a delay of a few seconds, the melt also exits from the medium length ventilation recess, after which it also exits from the next longest ventilation recess, etc. Once the cavity has been fully vented via the respective ventilation recesses, the connection of the respective ventilation recesses to the periphery is interrupted by successively advancing the screen carrier towards the filtering position, i.e. initially interrupting the connection of the shortest ventilation recess to the periphery, then interrupting the connection of the medium length ventilation recess, etc., until finally all ventilation recesses are separated from the periphery by retracting them into the housing.
[0026] According to one aspect, at least one or in particular all of the ventilation recesses are designed as grooves. During ventilation, the cavity may be in fluid communication exclusively with the fluid inlet channel and not with the fluid outlet channel. This allows for a gradual ventilation of the melt and its reintroduction into the production process. According to another aspect, at least one or all of the ventilation recesses are designed as ventilation holes.
[0027] According to an improvement of the present disclosure, the filtering device has a control unit, which is configured and designed in such a way that after venting the cavity, the control unit further moves the screen carrier in the direction of the filtering position via the acceleration position area by a control signal, so that the fluid outlet channel is initially placed in exclusive fluid communication with the cavity by the throttle recess, and the screen carrier is moved in the direction of the filtering position in such a way that the fluid pressure in the fluid inlet channel and / or in the fluid outlet channel remains within a predefinable pressure range. Thus, by utilizing the throttle recess, the filtering device can be controlled in a particularly advantageous manner. For example, a degree of reduction of the maximum pressure intensity can also be defined, which specifies to a certain extent the feed speed of the screen carrier. For example, if an excessive pressure drop is observed, the feed speed of the screen carrier is reduced. On the other hand, if a very low pressure drop, lower than a defined threshold, is observed, the feed speed of the screen carrier can be increased.
[0028] The screen carrier may be advanced continuously, e.g., in small increments, so that, e.g., the system pressure response can be awaited and evaluated. Such a control logic also has the advantage of being independent of material viscosity and throughput.
[0029] According to a second aspect of the present disclosure, the screen carrier is ventilated in the vent position area by supplying fluid via a fluid outlet channel, the screen carrier having a throttle recess arranged adjacent to the screen carrier inlet and in fluid communication with the cavity, the throttle recess opening a variable flow cross-section between the cavity and the fluid inlet channel depending on the position of the throttle recess relative to the fluid inlet channel (claim 13).
[0030] This modified structure of the throttle recess takes into account that in some filtration devices, the screen carrier is vented through the fluid outlet channel, rather than through the fluid inlet channel as described above. Therefore, in this modified configuration of the filtration device, the throttle recess is also located adjacent to the screen carrier inlet. Furthermore, the filtration device of the second aspect takes into account a different functional principle and location of the throttle recess while utilizing the same advantages and aspects as the filtration device of the first aspect of the present disclosure. In this regard, reference is made to the various findings above, which are incorporated by reference and the contents of which are made a part of this specification.
[0031] According to a third aspect of the present disclosure and according to an advantageous refinement of the first and / or second aspects of the present disclosure, the housing has a backflush supply channel configured to supply a backflush fluid to the filter element in a backflush position area from a clean side to a dirt side of the filter element and a backflush channel configured to discharge the backflush fluid after backflush, the screen carrier can be moved to the backflush position area, in which the backflush supply channel is in at least partial fluid communication with the clean side of the filter element and the backflush channel is in at least partial fluid communication with the dirt side of the filter element, the screen carrier has a backflush recess arranged between the backflush supply channel and the screen carrier outlet and in fluid communication with the cavity, the backflush recess opens a variable flow cross-section between the backflush supply channel and the cavity depending on the position of the backflush recess relative to the backflush supply channel in the backflush position area (claim 14).
[0032] This third aspect of the disclosure and / or an advantageous refinement of the disclosure makes use of the discovery that in the backflushing position the connection to the backflushing channel is particularly fully open with a large volume. The backflushing volume is adjusted via a backflushing recess between the backflushing supply channel and the cavity and thus in the vicinity of the clean side of the filter element. To that extent the backflushing volume can be adjusted as desired, the aim being to minimize pressure fluctuations in the system. Unlike the solutions known in the prior art that adjust the volume of contaminated melt used for backflushing, a particular advantage here is that relatively large contaminant particles do not affect the backflushing, whereas in the case of the devices known in the prior art it was observed in particular that the dirty particles have to pass through certain bottlenecks which can sometimes become clogged, as a result of which the backflushing becomes useless. The backflushing can be delicately adjusted due to the backflushing recess having a variable cross section along the longitudinal axis. In other words, the throttle adjustment is adjusted on the "clean" side, thereby preventing clogging. In the prior art, the throttle adjustment is performed on the dirt side, which inevitably creates a large opening and the associated inevitable pressure fluctuations that would otherwise be associated with clogging.
[0033] The present disclosure is improved by the fact that the backflush recess starts from the screen carrier outlet and extends along the longitudinal axis, seen from the filtration position, in the direction of the backflush supply channel. This configuration allows the feed volume of melt to be fine-tuned by varying the flow cross section between the backflush supply channel and the cavity. According to the present disclosure, the backflush recess has a cross section that varies in the direction of the longitudinal axis. The cross section of the backflush recess may start from the screen carrier outlet and taper in the direction of the longitudinal axis. According to one aspect, the cross section of the backflush recess starts from the screen carrier outlet and tapers linearly in the direction of the longitudinal axis. Thus, the melt used for backflush can be fed in a very precise dosage. According to one aspect, the cross section has a basic form in the shape of a wedge or in the shape of a notch. This basic form is another factor in aiding the precise dosing of the melt used for backflush.
[0034] According to one aspect, the filtration device has a control unit configured and designed such that during backflushing of the screen carrier, the control unit changes the position of the screen carrier by a control signal so that the fluid pressure in the fluid inlet channel and / or in the fluid outlet channel remains within a predefinable pressure range during backflushing, so that when the screen carrier is moved within the backflushing position area, a variable flow cross-section between the backflushing supply channel and the cavity is opened by the backflushing recess.
[0035] The disclosure (the present invention) has been described above with reference to a filtering device. In a second aspect, the disclosure relates to a method for operating a filtering device, in particular a filtering device of any one of the above aspects. In terms of this method, the disclosure achieves the above-identified aspect, which comprises the steps of venting the cavity, and further moving the screen carrier by a control signal after venting the cavity towards a filtering position, so that the fluid outlet channel is initially placed in exclusive fluid communication with the cavity by the throttle recess, and the screen carrier is moved towards the filtering position so that the fluid pressure in the fluid inlet channel and / or the fluid outlet channel remains within a definable pressure range during backflushing (claim 21).
[0036] Thus, the method utilizes the same advantages and aspects as the filtering device of the present disclosure, and vice versa. In this regard, reference is made to the various findings above, which are incorporated by reference and are incorporated herein in their entirety. What the method of the present disclosure achieves is, in summary, that by establishing a connection to the fluid outlet channel by means of a throttle recess, after venting the cavity, the melt therein can be accelerated very slowly and delicately, so that the fluid pressure in the fluid inlet channel or the fluid outlet channel remains within a defined pressure range.
[0037] This method, especially for a filtration device with a backflushing function, comprises a step of moving the screen carrier by a control signal in the direction of the backflushing position area so that the fluid pressure in the fluid inlet channel and / or in the fluid outlet channel remains within a definable pressure range during the backflushing, and is improved by the feature that the variable flow cross section between the backflushing supply channel and the cavity is opened by a backflushing recess, which is arranged between the backflushing supply channel and the screen carrier outlet and is in fluid communication with the cavity. This means that even during the backflushing, pressure fluctuations caused by the backflushing are prevented and that even relatively large particles do not affect the backflushing behavior.
[0038] Further features and advantages of the disclosure result from the following description in which the aspects are detailed with reference to the appended claims and the schematic drawings. [Brief description of the drawings]
[0039] [Figure 1] FIG. 2 illustrates a cross-sectional view of a first aspect of the filtration device of the present disclosure in a screen replacement position. [Diagram 2] 1 shows a first aspect of the filtering device of the present disclosure in cross section transverse to the longitudinal axis of the screen carrier; FIG. [Diagram 3] FIG. 1 shows a first aspect of the filtration device of the present invention in a first vent position. [Figure 4] FIG. 1 shows a first aspect of the filtration device of the present invention in a first vent position. [Diagram 5] FIG. 2 shows a first aspect of the filtration device of the present invention in a second vent position. [Figure 6] FIG. 2 shows a first aspect of the filtration device of the present invention in a second vent position. [Figure 7] FIG. 2 shows a first aspect of the filtration device of the present invention in a third vent position. [Figure 8]FIG. 2 shows a first aspect of the filtration device of the present invention in a third vent position. [Figure 9] FIG. 1 shows a first aspect of the filtration device of the present invention in an acceleration position region. [Figure 10] FIG. 1 shows a first aspect of the filtration device of the present invention in an acceleration position region. [Figure 11] FIG. 1 shows a first aspect of the filtration device of the present invention in filtration position. [Figure 12] FIG. 1 shows a first aspect of the filtration device of the present invention in filtration position. [Figure 13] FIG. 2 shows a second aspect of the filtration device of the present invention in filtration position. [Figure 14] FIG. 2 shows a second aspect of the filtration device of the present invention in a different view in the filtering position. [Figure 15] FIG. 2 shows a second aspect of the filtration device of the present invention in a different view in the filtering position. [Figure 16] 13A-13D show a second aspect of the screen carrier of the present disclosure in one operational position en route to a backflush position. [Figure 17] 13A-13C show a second aspect of the screen carrier of the present disclosure in alternative operational positions en route to a backflush position. [Figure 18] FIG. 13 illustrates a second view of the screen carrier of the present disclosure in a backflush position. [Figure 19] FIG. 13 illustrates a second view of the screen carrier of the present disclosure in a backflush position. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0040] FIG. 1 shows a filtering device 2 for filtering a fluid. The fluid is in particular a liquid plastic. The filtering device 2 has a housing 4. The housing 4 has a receptacle or receiver 6 for receiving a screen carrier or support 8. The housing 4 further has a fluid inlet channel 10 and a fluid outlet channel 12. The screen carrier 8 is received in the receiver 6. In the following description, reference is made only to the screen carrier 8 arranged at the top. However, the description applies analogously to the lower screen carrier 8. Each of the screen carriers 8 is received in the receiver 6 movably along a longitudinal axis 26. The screen carrier 8 has a screen carrier inlet 16, a screen carrier outlet 18 and a cavity 20 for receiving a filter element 22. The cavity 20 is in fluid communication with the screen carrier inlet 16 and the screen carrier outlet 18.
[0041] In FIG. 1, the upper screen carrier 8 is shown in a screen change position S. In this screen change position S, the filter element 22 can be changed. The screen carrier 8 can be moved essentially from the screen change position S shown in FIG. 1 through a ventilation position area E to a filtering position F. The screen carrier tank 8 has a throttle recess 24. The throttle recess 24 is arranged adjacent to the screen carrier outlet 18 and is in fluid communication with the cavity 20. The throttle recess 24 extends along a longitudinal axis 26 as seen from the screen change position S in the direction of the fluid outlet channel 12, starting from the screen carrier outlet 18. The throttle recess 24 has a cross section 28 that changes in the direction of the longitudinal axis 26. Starting from the screen carrier outlet 18, the cross section 28 of the throttle recess 24 tapers, in particular linearly, in the direction of the longitudinal axis 26. The cross section 28 has a basic form 32 in the form of a wedge. The screen carrier 8 further has an inlet throttle recess 34 located adjacent the screen carrier inlet 16 .
[0042] The inlet throttle recess 34 is likewise in fluid communication with the cavity 20. The inlet throttle recess 34 extends starting from the screen carrier inlet 16 along the longitudinal axis 26 as seen from the screen change position S shown in FIG. 1 in the direction of the fluid outlet channel 10. The inlet throttle recess 34 has a cross section 36 that changes in the direction of the longitudinal axis 26. The screen carrier 8 further has a first ventilation recess 40, a second ventilation recess 42 and a third ventilation recess 44. The ventilation recesses 40, 42, 44 put the cavity 20 in fluid communication with the surroundings depending on the position of the ventilation recesses 40, 42, 44 relative to the housing 4.
[0043] The ventilation recesses 40, 42, 44 extend along the longitudinal axis 26. When the screen carrier 8 moves from the screen changing position S shown in FIG. 1 in the direction of the filtering position F shown in FIG. 12, the cavity 20 is first ventilated via all three ventilation recesses 40, 42, 44, then, upon further movement of the screen carrier 8 in the direction of the filtering position F, via the first and second ventilation recesses 40, 42, and then, when the screen carrier 8 advances further, exclusively via the first ventilation recess 40. The second ventilation recess 42 has a shorter longitudinal extension along the longitudinal axis 26 than the first ventilation recess 40. The third ventilation recess 44 has a shorter longitudinal extension along the longitudinal axis 26 than the second ventilation recess 42. The ventilation recesses 40, 42, 44 are designed as grooves.
[0044] The filtering device 2 further comprises a control unit 52. The control unit 52 is configured and designed such that, after venting the cavity 20 in the acceleration position area B (compare Figures 9 and 10), the control unit moves the screen carrier 8 further towards the filtering position F by means of a control signal, so that the fluid outlet channel 12 is initially in exclusive fluid communication with the throttle recess 24 by means of the cavity 20, and the screen carrier 8 is moved towards the filtering position F such that the fluid pressure in the fluid inlet channel 10 and / or in the fluid outlet channel 12 remains within a definable pressure range.
[0045] Figure 2 is a side view of the filter device 2 in the operating state of Figure 1. Figures 3 and 4 show the filter device 2 in a first venting position. In this position, the inlet throttle recess 34 at least partially overlaps the fluid inlet channel 10. In other words, the fluid inlet channel 10 and the cavity 20 are in fluid communication through the inlet throttle recess 34 (indicated in Figure 4 by an arrow showing the direction of flow near the fluid inlet channel 10), so that the melt can flow from the fluid inlet channel 10 into the cavity 20, i.e. in a very finely pourable manner. Depending on the position of the inlet throttle recess 34 relative to the fluid inlet channel 10, a variable flow cross section 38 is opened between the cavity 20 and the fluid inlet channel 10.
[0046] In other words, the cavity 20 is exclusively in fluid communication with the fluid inlet channel 10 during venting. The vent recesses 40, 42, 44 are connected to the periphery of the filter device 2, so that when the melt flows into the cavity 20, air can flow out of the cavity 20. As can be seen from FIG. 4 for the same operating conditions, the vent recess 40 is in fluid communication with a first partial region 46 of the cavity 20. The vent recess 40 has a tapped hole. The second vent recess 42 is in fluid communication with a second partial region 48 of the cavity 20. The third vent recess 44 is in fluid communication with a third partial region 50 of the cavity 20.
[0047] In the operating condition shown in Figures 5 and 6, a direct connection now exists between the fluid inlet channel 10 and the cavity 20 due to the respective overlap with the screen carrier inlet 16. In the position shown in Figures 5 and 6, only the first vent recess 40 and the second vent recess 42 are connected to the atmosphere. This means that the melt is forced into the partial area of the cavity 20 that is connected to the vent recesses.
[0048] 7 and 8 show another venting step in which only the first vent recess 40 is connected to the periphery, so that a certain partial area 46 of the cavity 20, located adjacent to the filter element 22, is vented. In the acceleration position area B shown in FIGS. 9 and 10, the cavity 20 is completely vented and is in fluid communication with the fluid inlet channel 10 (as indicated by the flow direction arrow in FIG. 10). The vent recesses 40, 42, 44 are no longer connected to the periphery of the filter device 2. In the condition shown in FIGS. 9 and 10, the throttle recess 24 is now in contact with the fluid outlet channel 12. As a result, depending on the position of the throttle recess 24 relative to the fluid outlet channel 12, a variable flow cross section 30 is selectively and finely adjustable opened between the cavity 20 and the fluid outlet channel 12. Since the cavity 20 is connected to the fluid outlet channel 12 via the throttle recess 24, the stream of melt is moved from the cavity 20 in the direction of the fluid outlet channel 12, i.e. in a gentle manner such that the effect on the overall system pressure is kept within narrow limits. After the acceleration movement, the screen carrier 8 is pushed further to the right in the direction of the filtering position F. In the filtering position F, the cavity 20 is fully connected to both the fluid inlet channel 10 and the fluid outlet channel 12, and the filtering device 2 filters the passed fluid by the filter element 22. If the filter element 22 needs to be replaced, the screen carrier 8 is advanced to the position shown in FIG. 1, and the process starts again from the beginning.
[0049] 13-19 show another view of the filtration device 102. The filtration device 102 includes a housing 104 with a receptacle 106 that receives a screen carrier 108. The housing 104 further includes a fluid inlet channel 110 and a fluid outlet channel 112. Movably received within the receptacle 106 is a screen carrier 108 that is movably received along a longitudinal axis 126 and has a screen carrier inlet 116 and a screen carrier outlet 118 (see FIG. 14). The screen carrier 108 further includes a cavity 120 that receives a filter element 122. As can be seen particularly in FIG. 14, the cavity 120 is in fluid communication with the screen carrier inlet 116 and the screen carrier outlet 118. In the state shown in Figures 13 and 14, the screen carrier 108 is in a filtering position F, in which the fluid to be filtered flows into the cavity 12 via the fluid inlet channel 110, is filtered therein by the filter element 122, and then exits the cavity 120 via the fluid outlet channel 112.
[0050] The housing 104 further comprises a backflushing supply channel 154 configured to supply backflushing fluid to the filter element 122 from a clean side 156 to a dirt side 158 of the filter element 122 in a backflushing position region R. The housing 104 further comprises a backflushing channel 160 configured to discharge the backflushing fluid after backflushing. The screen carrier 108 may be moved in a backflushing position region where the backflushing supply channel 154 is in at least partial fluid communication with the clean side 156 of the filter element 122. The screen carrier 108 further comprises a backflushing recess or throttle recess 24. The backflushing recess 162 is arranged between the backflushing supply channel 154 and the screen carrier outlet 118 and is in fluid communication with the cavity 120. The backflushing recess 162 starts from the screen carrier outlet 118 and extends along the longitudinal axis 126, as seen from the filtration position F, in the direction of the backflushing supply channel 154. The backflushing recess 162 has a cross section 166 which varies in the direction of the longitudinal axis 126. The cross section 166 of the backflushing recess 162 starts from the screen carrier outlet 118 and tapers in a particularly linear manner in the direction of the longitudinal axis 126. The cross section 166 has a basic form 132 in the shape of a wedge.
[0051] The filtering device 102 further comprises a control unit 152. The control unit 152 is configured and designed in such a way that during backflushing of the screen carrier 108, the control unit changes the position of the screen carrier 108 by means of a control signal, such that the fluid pressure in the fluid inlet channel 110 and / or in the fluid outlet channel 112 remains within a predefinable pressure range during backflushing, so that when the screen carrier 108 is moved into the backflushing position area R, a variable flow cross section is opened by the backflushing recess 162 between the backflushing supply channel 154 and the cavity 120.
[0052] In the state shown in Figures 13 to 15, the filtration device 102 is in the filtering position F, as described above. A fluid or melt is fed through the fluid inlet channel 110, enters the cavity 120, where it is filtered by the filter element 122, and finally leaves the housing 104 through the fluid outlet channel 112 and the backflush feed / fluid outlet channel 154 (indicated by the arrows in Figure 14 showing the direction of flow). In the state shown in Figure 16, the screen carrier 108 has been moved to the right in the plane of the figure in such a way that the connection of the cavity 120 to the fluid outlet channel 112 is first interrupted. If the screen carrier 108 is now moved further to the right in the plane of the figure, as shown in Figure 17, the screen carrier 108 is also decoupled from the fluid inlet channel 110. However, at the same time, the cavity 120 is connected to the backflush channel 160.
[0053] In the state shown in Fig. 18, the screen carrier 108 has now been moved further to the right in such a way that the backflush recess 162 comes into contact with the backflush supply channel 154. Starting from the backflush supply channel 154, the already filtered backflush fluid, in particular the plastic melt, thus passes via the backflush recess 162 into the cavity 120 (in the direction of the flow arrow), in particular into the clean side 156 of the filter element 122. From here, the backflush fluid passes through the filter element 122 in the direction opposite to the filtration direction, cleaning the latter in the process, after which the contaminated backflush fluid is finally discharged via the backflush channel 160. The backflush recess 162 allows a very fine adjustment of the variable flow cross section 164 between the backflush supply channel 154 and the cavity 120, so that the effect on the overall system pressure during backflush remains within narrowly definable limits.
[0054] Following the above description of the method of operating the filter device, the manner of operation and steps of one method are described below with reference to the illustrated figures.
[0055] The method of operating the filtration device 2 is as follows: - venting the cavity 20, - after venting the cavity 20, moving the screen carrier 8 further in the direction of the filtering position F by the control signal so that the fluid outlet channel 12 is initially in exclusive fluid communication with the cavity 20 by the throttle recess 24, and moving the screen carrier 8 in the direction of the filtering position F in such a way that the fluid pressure in the fluid inlet channel 10 and / or the fluid outlet channel 12 remains within a definable pressure range.
[0056] The method also proceeds as follows: - moving the screen carrier 108 in the direction of the backflush position area R by a control signal provided by the control unit 52, so that the fluid pressure in the fluid inlet channel 110 and / or in the fluid outlet channel 112 remains within a definable pressure range during backflush, in which case when the screen carrier 108 moves in the direction of the backflush position area R, a variable flow cross-section 164 between the backflush supply channel 154 and the cavity 120 is opened by the backflush recess 162, in which case the backflush recess 162 is arranged between the backflush supply channel 154 and the screen carrier outlet 118 and is in fluid communication with the cavity 120. [Explanation of symbols]
[0057] 2 Filtration device 4. Housing 6 Receiver 8 Screen carrier or support 10 Fluid Inlet Channel 12 Fluid Outlet Channel 16 Screen carrier inlet 18 Screen carrier outlet 20 Cavity 22 Filter element 24 Throttle recess 26 Longitudinal axis 28 Cross section from throttle recess 30 Variable flow cross section at throttle recess 32 Basic form of wedge 34 Inlet throttle recess 36 Cross section of inlet throttle recess 38 Variable flow cross section at the inlet throttle recess 40 (1st) Ventilation recess 42 Second ventilation recess 44 Third ventilation recess 46 First partial region of cavity 48 Second partial region of cavity 50 Third subregion of cavity 52 Control Unit 102 Filtration device 104 Housing 106 Receiver 108 Screen carrier or support 110 Fluid Inlet Channel 112 Fluid Outlet Channel 116 Screen carrier inlet 118 Screen carrier outlet 120 Cavity 122 Filter element 126 Longitudinal axis 152 Control Unit 154 Backflush supply channel / fluid outlet channel 156 Clean side of filter element 158 Dirt side of filter element 160 Backflush Channel 162 Back flash recess 164 Variable flow cross section at the backflush recess 166 Cross section of backflush recess 168 Wedge Basic Form B Acceleration position area S Screen replacement position E Ventilation location area F filtration position R Backflush position area
Claims
1. A filtration device for filtering fluids, It has a housing equipped with a receiver for receiving a screen carrier, and the housing has a fluid inlet channel and a fluid outlet channel, The receiver has a screen carrier that is movably received along its longitudinal axis, the screen carrier has a screen carrier inlet, a screen carrier outlet, and a cavity for receiving a filter element, the cavity is in fluid communication with the screen carrier inlet and the screen carrier outlet, In a filtration device of a type that can move the screen carrier from the screen replacement position to the filtration position via the ventilation position region, The screen carrier has a throttle recess that is positioned adjacent to the screen carrier outlet or the screen carrier inlet and is in fluid communication with the cavity, The filtration device wherein the throttle recess opens a variable flow cross-section between the cavity and the fluid outlet channel depending on the position of the throttle recess relative to the fluid outlet channel.
2. The filtration apparatus according to claim 1, wherein the screen carrier can be moved from the ventilation position region through the acceleration position region to the filtration position, and the throttle recess opens a variable flow cross-section between the cavity and the fluid outlet channel depending on the position of the throttle recess relative to the fluid outlet channel in the acceleration position region.
3. The filtration apparatus according to claim 1, wherein the throttle recess begins at the screen carrier outlet and extends along the longitudinal axis when viewed from the screen replacement position in the direction of the fluid outlet channel.
4. The filtration apparatus according to claim 1, wherein the throttle recess has a cross-section that changes in the direction of the longitudinal axis.
5. The filtration apparatus according to claim 4, wherein the cross-section of the throttle recess tapers in the direction of the longitudinal axis, starting from the screen carrier outlet.
6. The filtration apparatus according to claim 4, wherein the cross-section of the throttle recess tapers linearly in the direction of the longitudinal axis, starting from the screen carrier outlet.
7. The filtration apparatus according to claim 4, wherein the cross-section has a basic form that is wedge-shaped or notched.
8. The filtration apparatus according to claim 2, wherein the fluid inlet channel and the fluid outlet channel are arranged in the housing such that when the screen carrier moves from the screen replacement position towards the filtration position via the ventilation position region and the acceleration position region, the cavity in the ventilation position region initially has fluid communication with the fluid inlet channel, and as the screen carrier moves further towards the filtration position, the cavity in the acceleration position region is further brought into fluid communication with the fluid outlet channel via the throttle recess.
9. The screen carrier, located adjacent to the screen carrier inlet, has an inlet throttle recess that is in fluid communication with the cavity, The filtration apparatus according to claim 5, wherein the inlet throttle recess opens a variable flow cross-section between the cavity and the fluid inlet channel depending on the position of the inlet throttle recess relative to the fluid inlet channel within the ventilation position region.
10. The inlet throttle recess begins at the screen carrier inlet and extends along the longitudinal axis in the direction of the fluid inlet channel, as viewed from the screen replacement position. The filtration apparatus according to claim 9, wherein the inlet throttle recess has a cross-section that changes in the direction of the longitudinal axis.
11. The filtration apparatus according to claim 9, wherein the cavity within the ventilation position region is exclusively in fluid communication with the fluid inlet channel.
12. The filtration apparatus according to claim 2, further comprising a control unit, wherein, after the cavity has been vented, the control unit is configured and designed to further move a screen carrier in the direction of the filtration position via the acceleration position region by a control signal, so that the fluid outlet channel is initially in exclusive fluid communication with the cavity by the throttle recess, and the screen carrier is moved in the direction of the filtration position such that the fluid pressure in the fluid inlet channel and / or the fluid outlet channel remains within a defined pressure range.
13. The screen carrier is ventilated within the ventilation position region by supplying fluid through the fluid outlet channel. The screen carrier has a throttle recess positioned adjacent to the screen carrier inlet and in fluid communication with the cavity, The filtration apparatus according to claim 1, wherein the throttle recess opens a variable flow cross-section between the cavity and the fluid inlet channel depending on the position of the throttle recess relative to the fluid inlet channel.
14. The housing has a backflash supply channel configured to supply backflash fluid to the filter element in the backflash position region from the clean side to the dirt side of the filter element. The filtration device has a back-flushing channel configured to discharge the back-flushing fluid after back-flushing, The screen carrier can be moved to the back flash position region, in which the back flash supply channel is in at least partially fluid communication with the clean side of the filter element, and the back flash channel is in at least partially fluid communication with the dirt side of the filter element. The screen carrier is positioned between the back flash supply channel and the screen carrier outlet and has a back flash recess that is in fluid communication with the cavity. The filtration apparatus according to claim 1, wherein the back flash recess opens a variable flow cross-section between the back flash supply channel and the cavity, depending on the position of the back flash recess relative to the back flash supply channel within the back flash position region.
15. The filtration apparatus according to claim 14, wherein the back flash recess begins at the screen carrier outlet and extends along the longitudinal axis when viewed from the filtration position in the direction of the back flash supply channel.
16. The filtration apparatus according to claim 15, wherein the back flashing recess has a cross-section that changes in the direction of the longitudinal axis.
17. The filtration apparatus according to claim 15, wherein the cross-section of the back flash recess tapers in the direction of the longitudinal axis, starting from the screen carrier outlet.
18. The filtration apparatus according to claim 15, wherein the cross-section of the back flash recess tapers linearly in the direction of the longitudinal axis, starting from the screen carrier outlet.
19. The filtration apparatus according to claim 14, wherein the cross-section of the back flash recess has a basic shape of a wedge or a notch.
20. The filtration apparatus according to claim 14, further comprising a control unit, wherein the control unit is configured and designed to change the position of the screen carrier by a control signal during backflushing of the screen carrier, so that the fluid pressure in the fluid inlet channel and / or the fluid outlet channel remains within a defined pressure range during backflushing, and as a result, when the screen carrier is moved within the backflushing position region, the variable flow cross section between the backflushing supply channel and the cavity is opened by the backflushing recess.
21. A method for backflushing the filtration apparatus according to claim 1, The steps include ventilating the cavity, A method comprising the steps of: after the screen carrier has been vented through the cavity, moving it further in the direction of the filtration position by a control signal so that the fluid outlet channel is initially in exclusive fluid communication with the cavity by the throttle recess, and so that the screen carrier is moved in the direction of the filtration position so that the fluid pressure in the fluid inlet channel and / or the fluid outlet channel remains within a controllable pressure range during backflushing.
22. A method for backflushing the filtration apparatus according to claim 14, The steps include moving the screen carrier in the direction of the backflash position region by a control signal so that the fluid pressure in the fluid inlet channel and / or the fluid outlet channel remains within a defined pressure range during backflash, A method wherein the variable flow cross-section between the backflash supply channel and the cavity is opened by the backflash recess, the backflash recess is located between the backflash supply channel and the screen carrier outlet and is in fluid communication with the cavity.