Filtering device for filtering fluids and method for venting and backflushing

Abstract

An apparatus may include a housing having a receptacle for receiving a screen carrier and having a fluid inlet channel and a fluid outlet channel. Further, the apparatus may include a screen carrier movably received within the container and having a screen carrier inlet, a screen carrier outlet, and a cavity for receiving a filter element, where the cavity is in fluid communication with the screen carrier inlet and the screen carrier outlet. The screen carrier can be moved from a screen changing position (S) into a filtering position (F) via an exhaust position region. Further, the apparatus may include an accumulator fluidly connectable to the screen carrier inlet and / or the screen carrier outlet, and configured to store fluid supplied via the screen carrier inlet and / or the screen carrier outlet, and to control the supply of fluid into the accumulator.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of German Patent Application No. 102022124308.7 filed on September 21, 2022, the entire contents of which are incorporated herein by reference for all purposes as if fully set forth herein. Technical Field

[0003] The invention relates to a filter device for filtering fluids, in particular liquefied plastics, the filter device comprising: a housing having a container for receiving a screen carrier and having a fluid inlet channel and a fluid outlet channel; a screen carrier, which is movably received inside the container along a longitudinal axis and has a screen carrier inlet, a screen carrier outlet and a cavity for receiving a filter element, wherein the cavity is in fluid communication with the screen carrier inlet and the screen carrier outlet, and wherein the screen carrier can be moved from a screen replacement position to a filtering position via a venting position area. The invention also relates to a method for the filter device. Background Art

[0004] Filter devices are used in plastic processing machines, for example, when the purity of the plastic being processed must meet toughness requirements. They are usually arranged between an extruder and an applicator, which melts and conveys the plastic. Such filter devices and methods for filtering fluids, in particular liquefied plastics, are known from the prior art and have a screen carrier in which a filter element (also called a screen) is arranged.

[0005] When such filters or filter elements have been in operation for a period of time, they must be replaced or cleaned. To replace the filter element, the screen carrier is moved from the filter position (also called the production position) to the screen replacement position, in which the filter element can be accessed and replaced.

[0006] Once the filter element has been replaced, it must be returned to the production process. This poses a fundamental challenge in that the inner space of the screen carrier, referred to as the cavity, is usually filled with air after the screen has been replaced and this air must be prevented from being introduced into the plastic fluid flow. After the screen has been replaced, the screen carrier is first moved to the venting position area for this purpose, in which the liquefied plastic flows into the screen cavity and the air contained therein is discharged to the outside via the venting channel.

[0007] In most cases, the plastic used for backflushing is taken from the plastic fluid flow to be filtered. This aspect also plays a role when backflushing the filter elements in the direction opposite to the filtering direction with clean or clean plastic melt to clean them, during which the filter elements are backflushed. In most cases, the plastic used for backflushing is also taken from the plastic fluid flow to be filtered in the form of a volume flow. This volume flow is usually regulated and kept within limits by varying the pressure level. However, there are limitations to this regulation of the pressure level. If the plastic fluid flow is vented or backflushed too quickly, this can have a negative impact on the volume flow of the plastic and the system pressure. For example, when using spinning nozzles, such pressure fluctuations can have an adverse effect on the spinning process. The product quality can be impaired or the spinning wire can even break.

[0008] In order to mitigate or even completely prevent these negative consequences, it is known from the prior art to only partially open a venting / recoil channel, via which the venting or recoil fluid is supplied or discharged, in order to control the total system pressure. However, this approach overcomes limitations if very high system pressures are present, or if the viscosity of the melt is very low. It may not be possible to ensure the prevention of pressure fluctuations. Depending on the properties of the melt, it may also be necessary to open the recoil channel only very slightly, i.e. with a small opening cross section. However, this may lead to a blockage of the cross section by larger dirt particles, which also means that the pressure cannot be adjusted in an ideal manner.

[0009] Against this background, the object of the present invention is to develop a filtering device and a method of the initially specified type such that the disadvantages identified in the prior art are eliminated as far as possible. In particular, the object of the present invention is to specify a filtering device and a filtering method in which the volume flow of the melt leaving the filtering device and the total system pressure remain as constant as possible during a screen changing operation or during backflushing of the filter element, and in which the filtering device has a low overall system complexity. Summary of the invention

[0010] According to the invention, this object is achieved by a filtering device which is initially specified by an accumulator which can be fluidically connected to a screen carrier inlet and / or a screen carrier outlet and is configured to store fluid supplied via the screen carrier inlet and / or the screen carrier outlet and to control the supply of fluid into the accumulator so that the volume flow rate of the melt, in particular the volume flow rate of the melt leaving the filtering device and being supplied to downstream system components, is maintained within a definable range of volume flow rate.

[0011] The present invention makes use of the knowledge that by controlling how the fluid is fed into the accumulator, for example in the form of a volume flow or a mass flow, the cavity can be reliably vented even at high outlet-side pressures and low viscosities. Typically, the fluid for venting or backflushing is fed to the accumulator, received in the accumulator and released to the surroundings after venting or backflushing. By controlling how the fluid is fed to the accumulator, the total system pressure can be kept within tightly defined limits and a constant volume flow of the melt leaving the filtering device and being fed to downstream system components can be ensured. Thus, in a sense, the accumulator performs the function of a hydraulic buffer (arrester) when the cavity is vented or backflushed, with the result that the material passes through the cavity in a finely metered manner. The filtering device according to the invention is also suitable for a large pressure and viscosity range with respect to the melt to be processed. The accumulator is preferably an accumulator through which there is a non-permanent flow. A downstream system component is understood to be a component arranged downstream of the filtering device. For example, it can be a forming tool.

[0012] The invention is developed by a filter device having a control unit, which is configured to control the supply of fluid into the accumulator so that the volume flow of the melt, in particular the volume flow of the melt leaving the filter device and being supplied to downstream system components, remains within a definable range of volume flow. By means of the control unit according to the invention, the supply of the fluid into the accumulator, for example in mass or volume flow, is controlled so that the volume flow of the melt as a whole remains within a definable range of volume flow. As a result, the system pressure and the total system pressure remain within the definable pressure range.

[0013] According to a preferred embodiment, alternatively, the change in the volume flow of the melt is determined with the aid of a pressure sensor, which is preferably arranged in the filter device, in particular in the fluid outlet channel. The volume flow of the melt is preferably determined based on the system pressure, which is determined here as an auxiliary variable. In other words, by measuring the pressure with a pressure sensor, conclusions can be drawn about the volume flow of the melt through the filter device or the entire system, since changes in the volume flow always lead to changes in pressure. According to one embodiment, the pressure is not necessarily measured in the filter device, but can also be measured at any advantageous position elsewhere in the system. According to one embodiment, the pressure is measured on the downstream side of the filter device and on the inlet side of the forming tool or downstream pressure generator.

[0014] The invention is developed by arranging the accumulator in a separate housing or in the screen carrier housing. If the accumulator is arranged in a separate housing, this offers the advantage that an existing device can be expanded with a corresponding accumulator without expensive or time-consuming modifications. If the accumulator is arranged directly in the housing of the filter device, a particularly compact filter device can be specified.

[0015] According to a further embodiment, the housing has an accumulator connecting channel, which fluidically connects the screen carrier inlet to an accumulator inlet depending on the position of the screen carrier relative to the housing. The screen carrier is preferably vented in the venting position area by supplying fluid via the fluid outlet channel, wherein the accumulator connecting channel provides fluid communication between the screen carrier inlet and the inlet of the accumulator in the venting position area.

[0016] The fluid for venting, in particular the plastic melt, and any air pockets thus reach the accumulator via the accumulator connecting channel and can be received therein.

[0017] The invention is developed by a screen carrier which is movable into the area of ​​a backflushing position in which a backflushing fluid is supplied to the filter element from the clean side of the filter element to the dirty side of the filter element, wherein an accumulator connecting channel provides a fluid connection between the inlet of the screen carrier and the inlet of the accumulator in the area of ​​the backflushing position. In this way, the fluid for backflushing, which usually contains impurities previously contained in the screen, can also be supplied to the accumulator and received therein.

[0018] The screen carrier preferably has an outlet channel which provides the accumulator connecting channel with fluid communication with the surroundings of the filtering device when the screen carrier is in the accumulator emptying position, so that the fluid received in the accumulator can be discharged to the surroundings, and wherein the accumulator connecting channel is disconnected from the screen carrier inlet in the accumulator emptying position. This allows the accumulator to be emptied toward the surroundings of the filtering device. In this case, the accumulator connecting channel is disconnected from the screen carrier inlet, thereby ensuring that the fluid received in the accumulator does not return to the system.

[0019] According to a preferred embodiment, the accumulator emptying position of the screen carrier matches the filtering position of the screen carrier. This means that after venting or backflushing the chamber by moving the screen carrier into the filtering position, the screen carrier performs its filtering function and at the same time, in the filtering position matching the accumulator emptying position, the accumulator is connected to the surroundings of the filtering device via the outlet channel so that in the filtering position, the fluid can be discharged from the accumulator to the surroundings. So, in other words, there is functional integration here. Moving the screen carrier into the filtering position connects the accumulator to the surroundings at the same time. No additional valves or the like are required in this construction.

[0020] The invention is developed by implementing the accumulator as a piston accumulator. The piston accumulator preferably has an accumulator chamber and a piston arranged in the accumulator chamber and drivable by an actuator, the supply of fluid into the accumulator being controlled by the piston. The actuator is preferably implemented as a lifting cylinder, which is configured to drive the piston along the longitudinal axis of the accumulator. In the present embodiment, the mass or volume flow supplied to the accumulator is therefore controlled by driving the piston along the longitudinal axis of the accumulator. At the same time, by driving it in the opposite direction, the piston can be used to discharge the fluid received in the accumulator out of the accumulator, for example towards the surroundings of the filtering device.

[0021] According to an alternative embodiment, the actuator is implemented as a rotary lift cylinder configured to drive a piston rotationally along the longitudinal axis of the accumulator and inside the accumulator chamber, wherein the piston has a longitudinal groove that interacts with the piston accumulator inlet and the piston accumulator outlet such that fluid communication with the piston accumulator inlet or the piston accumulator outlet is released depending on the rotational position of the piston. Thus, in a sense, the piston performs two functions: firstly, the piston allows a controlled and adequately metered entry of fluid into the accumulator chamber, and by movement of the piston in the opposite direction, it also allows fluid to be removed from the accumulator chamber, while at the same time, due to the rotation of the piston, the piston accumulator inlet or the piston accumulator outlet is released, which means that no additional valve is required in the area of ​​the inlet or outlet.

[0022] According to another alternative embodiment, the piston accumulator has a piston accumulator outlet and a valve with a valve pin, wherein the piston accumulator outlet is blocked or released depending on the position of the valve pin relative to the piston accumulator outlet. According to a preferred embodiment, the accumulator has a control valve connected to the accumulator chamber and configured to apply pressure to the accumulator chamber or to vent it. In this way, the accumulator can be prepared for the respective use before the accumulator is used for venting or backflushing.

[0023] The present invention is developed by a screen carrier as a first screen carrier, wherein the filter device has at least a second screen carrier, which is movably received in a housing and has a second screen carrier inlet, a second screen carrier outlet and a second cavity for receiving a second filter element, wherein the housing has at least a second accumulator connection channel, which fluidically connects the second screen carrier inlet to the inlet of the accumulator depending on the position of the second screen carrier relative to the housing. By providing additional screen carriers, it can be ensured that the filter device has permanent operability. For example, when the first screen carrier is in an exhaust or backwash position, another screen carrier can ensure that the filtration is in operation, and vice versa. According to a preferred embodiment, the filter device has three or more screen carriers, which are implemented similarly to the first two screen carriers and are movably received in the housing. Each screen carrier can have one or more cavities.

[0024] The invention has been described above with reference to a filter device. In a second aspect, the invention relates to a method for venting a filter device, in particular a filter device according to any one of the above embodiments. According to the invention, the method comprises the following steps: moving a screen carrier of the filter device into a venting position area; supplying a venting fluid via a fluid outlet channel of the filter device so that the air in the cavity of the screen carrier is exhausted toward the screen carrier inlet; supplying the exhausted air and / or the venting fluid from the screen carrier inlet to an accumulator, wherein the supply of the fluid to the accumulator is controlled so that the volume flow of the melt, in particular the volume flow of the melt leaving the filter device and being supplied to downstream system components, is maintained within a definable range of the volume flow. Thus, when the screen carrier is vented via the screen carrier outlet, the system pressure is maintained within definable limits.

[0025] In a third aspect, the present invention relates to a method for venting a filter device, in particular a filter device according to any one of the above embodiments. The method according to the third aspect of the present invention comprises the following steps:

[0026] The screen carrier of the filter device is moved into the exhaust position area; exhaust fluid is supplied via the fluid inlet channel of the filter device so that the air in at least one cavity of the screen carrier is exhausted toward the screen carrier outlet; the exhausted air and / or exhaust fluid is supplied from the screen carrier outlet to the accumulator, wherein the supply of fluid to the accumulator is controlled so that the volume flow rate of the melt, in particular the volume flow rate of the melt leaving the filter device and being supplied to downstream system components, is maintained within a definable range of the volume flow rate. The method according to the third aspect is an alternative solution to the method according to the second aspect; in the method according to the third aspect, the exhaust fluid is supplied via the fluid inlet channel and is transferred to the accumulator via the screen carrier outlet. The method according to the third aspect utilizes the same advantages and preferred embodiments as the filter device according to the present invention and the method according to the second aspect. Reference is made to the above observations in this regard, the contents of which are incorporated herein by reference.

[0027] In a fourth aspect, the present invention relates to a method for backflushing a filter device, in particular a filter device according to any one of the above embodiments. The method comprises the following steps: moving a screen carrier of the filter device into a backflushing position area; supplying a backflushing fluid via a fluid outlet channel of the filter device so that the backflushing fluid is supplied to the filter element from the clean side to the dirty side of the filter element, and pressing the backflushing fluid toward the screen carrier inlet; supplying the backflushing fluid from the screen carrier inlet to an accumulator, wherein the supply of the fluid to the accumulator is controlled so that the volume flow of the melt, in particular the volume flow of the melt leaving the filter device and being supplied to a downstream system component, is maintained within a definable range of the volume flow.

[0028] This also ensures that during backflushing, the volume flow of the melt leaving the filter device and being fed to downstream system components, and therefore also the total system pressure, remains within definable limits, thereby ensuring the desired product quality over a wide range of operating pressures and viscosities. The method according to the fourth aspect utilizes the same advantages and preferred embodiments as the filter device according to the invention and the methods according to the second and third aspects. Reference is made in this regard to the above observations, the contents of which are incorporated herein by reference.

[0029] The method is developed by closing an inlet of the accumulator, opening an outlet of the accumulator, and discharging a fluid contained in the system out of the accumulator via the outlet.

[0030] The method is also developed by performing the steps of closing the inlet and opening the outlet by moving the screen carrier to the accumulator empty position, in which the accumulator connecting channel provides fluid communication between the accumulator and the surrounding environment of the filtration device, and the screen carrier inlet is disconnected. This ensures that no fluid enters the process when the fluid is discharged from the accumulator.

[0031] Further features and advantages of the invention are derived from the dependent claims and the following description, in which embodiments are described in more detail with reference to the schematic drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In the accompanying drawings,

[0033] FIG. 1 a shows a first embodiment of a filter device according to the present invention;

[0034] FIG. 1 b shows a detail “X” of the filtering device according to FIG. 1 a , in particular a detail of the melt accumulator;

[0035] Figure 2 An embodiment of a filter device according to the invention is shown in a filter or reservoir emptying position;

[0036] Figure 3 and Figure 4 An embodiment of the filter device according to the invention is shown in the exhaust position area;

[0037] Figure 5 An embodiment of a filter device according to the invention is shown in a backflushing position;

[0038] Figure 6 and Figure 7 An embodiment of a filter device according to the invention is shown in an accumulator emptying position or filtering position;

[0039] 8a, 8b and 8c show cross-sectional views of alternative embodiments of the accumulator according to the present invention;

[0040] 9a and 9b show cross-sectional views of alternative embodiments of an accumulator according to the present invention;

[0041] Fig.10 , Fig.11 and Fig.12 A block diagram of a method according to the invention is shown. DETAILED DESCRIPTION

[0042] Figure 1 to Figure 7 A first embodiment of a filter device 2 is shown. The filter device 2 is suitable for filtering fluids, in particular liquefied plastics. The filter device 2 has a housing 4. The housing 4 has a container 6 for receiving a screen carrier and a fluid inlet channel 8 and a fluid outlet channel 10. A screen carrier 14 is movably received in the container 6 along a longitudinal axis 12. The screen carrier 14 has a screen carrier inlet 16, a screen carrier outlet 18 and a cavity 20, in which a filter element 22 is received. The cavity 20 is in fluid communication with the screen carrier inlet 16 and the screen carrier outlet 18. The screen carrier 14 can be moved from Figure 2 The filtering position F shown in FIG. 1a is moved to the screen replacement position S shown in FIG. 1a, and is moved to the screen replacement position S shown in FIG. Figure 3 and Figure 4 The exhaust position or exhaust position area E is shown.

[0043] The filter device 2 further comprises an accumulator 24a-c which is fluidically connectable to the screen carrier inlet 16 and is adapted to store the fluid supplied via the screen carrier inlet 16 and to control the supply of the fluid into the accumulator 24. According to an alternative embodiment not shown here, it is also conceivable that the accumulator is fluidically connectable to the screen carrier outlet 18 and is adapted to store the fluid supplied via the screen carrier outlet 18 and to control the supply of the fluid into the accumulator 24 accordingly.

[0044] The filter device 2 has a control unit 26. The control unit 26 is configured to control the supply of fluid into the accumulator 24 so that the volume flow Q of the melt, in particular the volume flow Q of the melt leaving the filter device 2 and being supplied to downstream system components, is maintained within a definable range ΔQ of the volume flow. The change in the volume flow Q of the melt is preferably determined indirectly, in particular alternatively by a pressure sensor 28 arranged in the fluid outlet channel 10. In the embodiment shown, the accumulator 24 is arranged in a separate housing 30, which is connected to the housing 4 of the filter device 2. The housing 4 has an accumulator connecting channel 32, which fluidically connects the screen carrier inlet 16 to the accumulator inlet 57 depending on the position of the screen carrier 14 relative to the housing 4. The screen carrier 14 is driven by a screen carrier drive 78. The screen carrier 14 also has an exhaust groove 80. At least one housing exhaust groove 81 (also called collecting groove) is arranged in the housing 4. Filter element 22 (also referred to as a screen) is held in place by screen support plate 82 and screen retainer 84 .

[0045] exist Figure 3 and Figure 4 In the venting position region E shown, the screen carrier 14 is vented by supplying fluid via the fluid outlet passage 10. In the venting position region E, the accumulator connecting passage 32 provides fluid communication between the screen carrier inlet 16 and the outlet 27 of the accumulator 24.

[0046] like Figure 5 As shown, the screen carrier 14 can also be moved into a backflush position region R. In the backflush position region R, backflush fluid is supplied to the filter element 22 from the clean side 36 of the filter element 22 to the dirty side 34 of the filter element 22. In the backflush position region R, the accumulator connecting channel 32 provides fluid communication between the screen carrier inlet 16 and the inlet 25 of the accumulator 24.

[0047] The screen carrier 14 also has an outlet passage 38. For example, Figure 6 In the illustrated reservoir emptying position SE, the outlet passage 38 provides fluid communication between the reservoir connecting passage 32 and the surrounding environment 40 of the filter device 2, so that the fluid received in the reservoir 24 can be discharged to the surrounding environment 40. In the reservoir emptying position SE, the reservoir connecting passage 32 is also disconnected from the screen carrier inlet 16. Figure 2 or Figure 6 As shown, the accumulator emptying position SE of the screen carrier 14 matches the filtering position F of the screen carrier 14 .

[0048] In Figures 1 to Figure 7In the first embodiment of the filter device 2 shown, the accumulator 24a is implemented as a piston accumulator 42. The piston accumulator 42 has an accumulator chamber 44 and a piston 46 arranged in the accumulator chamber 44 and which can be driven by an actuator 48. The position of the actuator 48 is measured by the position measuring device 19. The supply of fluid into the accumulator 24, that is, in particular the mass or volume flow, is controlled by the piston 46, in particular its translational movement. The actuator 48 is implemented as a lifting cylinder 50. The lifting cylinder 50 is configured to drive the piston 46 along the longitudinal axis 54 of the accumulator. As shown in detail in Figure 1b, the accumulator 24a has a control valve 64. The control valve 64 is connected to the accumulator chamber 44 and is configured to apply pressure to the accumulator chamber 44 or to exhaust it. For example, as Figure 4 As shown, and can also be seen from FIG. 1 a, the screen carrier 14 is a first screen carrier 14, wherein the filter device 2 has a second screen carrier 66 movably received in the housing 4. Figure 4 As shown, screen carrier 66 has a second screen carrier inlet 68. In this regard, housing 4 has at least a second accumulator connection passage 76 that fluidly connects second screen carrier inlet 68 to inlet 25 of accumulator 24a depending on the position of second screen carrier 66 relative to housing 4.

[0049] In Figure 8a to Figure 8C In the embodiment of the accumulator 24b shown, the actuator 48 is implemented as a rotary lift cylinder 52. The rotary lift cylinder 52 is configured to drive the piston 46 along the accumulator longitudinal axis 54 and to drive the piston 46 rotationally inside the accumulator chamber 44. The piston 46 has a longitudinal groove 56. The longitudinal groove 56 is designed to interact with a piston accumulator inlet 57 and a piston accumulator outlet 58 so that fluid communication with the piston accumulator inlet 57 or the piston accumulator outlet 58 is released depending on the rotational position of the piston 46.

[0050] 9a and 9b show another alternative embodiment of the accumulator 24c. The accumulator 24c shown therein is implemented as a piston accumulator 42 and has a piston accumulator outlet 58 and a valve 60 with a valve pin 62. The piston accumulator outlet 58 is blocked or released depending on the position of the valve pin 62 relative to the piston accumulator outlet 58, and the valve pin has a valve pin passage 63. Figures 9a and 9b also show an actuator outlet valve 86 and an outlet valve position detector 88.

[0051] Fig.10An embodiment of a method 100 for venting a filter device 2 is shown. The method comprises the following steps: moving 102 a screen carrier 14 of the filter device 2 into a venting position region E; supplying 104 a venting fluid via a fluid outlet channel 10 of the filter device 2 such that air in a cavity 20 of the screen carrier is vented toward a screen carrier inlet 16; supplying 106 the vented air and / or venting fluid from the screen carrier inlet 16 to an accumulator 24, wherein the supply of fluid into the accumulator 24 is controlled such that a volume flow Q of the melt, in particular a volume flow Q of the melt leaving the filter device 2 and being supplied to downstream system components, is maintained within a definable range ΔQ of the volume flow; closing 108 an inlet 25 of the accumulator 24; opening 110 an outlet 27 of the accumulator 24; and discharging 112 the fluid in the accumulator 24 from the accumulator 24 via the outlet 27.

[0052] Fig.11 An embodiment of a method 200 for venting a filter device 2, in particular a filter device 2 according to any of the above-described embodiments, is shown. The method 200 comprises the following steps: moving 202 a screen carrier 14 of the filter device 2 into a venting position region E; supplying 204 a venting fluid via a fluid inlet channel 8 of the filter device 2 such that air in at least one cavity 20 of the screen carrier 14 is vented toward a screen carrier outlet 18; supplying 206 the vented air and / or venting fluid from the screen carrier outlet 18 to an accumulator 24, wherein the supply of fluid into the accumulator 24 is controlled such that a volume flow Q of the melt, in particular a volume flow Q of the melt leaving the filter device and being supplied to a downstream system component, is maintained within a definable range ΔQ of the volume flow; closing 208 an inlet 25 of the accumulator 24; opening 210 an outlet 27 of the accumulator 24; and discharging 212 the fluid in the accumulator 24 from the accumulator 24 via the outlet 27.

[0053] Fig.12An embodiment of a method 300 for backflushing a filter device 2, in particular a filter device 2 according to any of the above-described embodiments, is shown. The method 300 comprises the following steps: moving 302 a screen carrier 14 of the filter device 2 into a backflushing position region RS; supplying 304 a backflushing fluid via a fluid outlet channel 10 of the filter device 2 such that the backflushing fluid is supplied to the filter element 22 from the clean side 36 to the dirty side 34 of the filter element 22 and the backflushing fluid is pressed toward the screen carrier inlet 16; supplying 306 the backflushing fluid from the screen carrier inlet 16 to the accumulator 24, wherein the supply of fluid into the accumulator 24 is controlled such that a volume flow Q of the melt, in particular a volume flow Q of the melt leaving the filter device 2 and being supplied to downstream system components, is maintained within a definable range ΔQ of the volume flow; closing 308 an inlet 25 of the accumulator 24; opening 310 an outlet 27 of the accumulator 24; discharging 312 the fluid contained in the accumulator 24 from the accumulator 24 via the outlet 27.

[0054] The steps of closing 108 inlet 25 and opening 110 outlet 27 are performed by moving screen carrier 14 into accumulator empty position SE, wherein accumulator connecting passage 32 provides fluid communication between accumulator 24 and ambient environment 40 of filter device 2 and screen carrier inlet 16 is disconnected.

[0055] Reference numerals list

[0056] 2 Filtration device

[0057] 4 Shell

[0058] 6 Screen Carrier Container

[0059] 8 Fluid inlet channels

[0060] 10 fluid outlet channels

[0061] 12 Longitudinal axis of the container

[0062] 14 (First) Screen Carrier

[0063] 16 (First) Screen Carrier Entry

[0064] 18 (First) Screen Carrier Outlet

[0065] 19 Position measuring device

[0066] 20 (first) cavity

[0067] 22 filter element

[0068] 24a-c Accumulator

[0069] 25 Accumulator inlet

[0070] 26Control Unit

[0071] 27 Accumulator outlet

[0072] 28 Pressure Sensor

[0073] 30 separate shells

[0074] 32 Accumulator connection channel

[0075] 34 Dirt side of filter element

[0076] 36. Clean side of filter element

[0077] 38 Exit Channel

[0078] 40 Surrounding environment of the filter device

[0079] 42 Piston Accumulator

[0080] 44 Storage Room

[0081] 46 piston

[0082] 48 Actuator

[0083] 50 Lifting Cylinder

[0084] 52 Rotary Lift Cylinder

[0085] 54 longitudinal axis of the accumulator

[0086] 56 longitudinal grooves

[0087] 57 Piston accumulator inlet

[0088] 58 Piston accumulator outlet

[0089] 60 valve

[0090] 62 valve pin

[0091] 63 Valve pin passage

[0092] 64 control valve

[0093] 66 Second sieve carrier

[0094] 68 Second screen carrier entrance

[0095] 76 Second accumulator connection channel

[0096] 78.Screen carrier drive device

[0097] 80 Exhaust grooves in the screen carrier

[0098] 81 Shell exhaust groove

[0099] 82 screen support plate

[0100] 84 Screen Retainer

[0101] 86 Actuator Outlet Valve

[0102] 88 outlet valve position detector

[0103] 100 Method for venting a filter device

[0104] 102 Move the screen carrier to the exhaust position area

[0105] 104 supplies exhaust fluid via the fluid outlet passage

[0106] 106 supplies the bled air and / or exhaust fluid to an accumulator.

[0107] 108 Close the inlet of the accumulator

[0108] 110 Open the outlet of the accumulator

[0109] 112 discharges the fluid from the accumulator.

[0110] 200 Method for venting a filter device

[0111] 202 Move the screen carrier to the exhaust position area

[0112] 204 supplies exhaust fluid via the fluid inlet passage

[0113] 206 supplies bled air and / or exhaust fluid to an accumulator.

[0114] 208 Close the inlet of the accumulator

[0115] 210 Open the outlet of the accumulator

[0116] 212 discharges fluid from the accumulator.

[0117] 300 Method for backflushing a filter device

[0118] 302 Move the screen carrier to the recoil position area

[0119] 304 supplies backflushing fluid through the fluid outlet channel of the filter device

[0120] 306 supplies backflushing fluid from the screen carrier inlet to the accumulator.

[0121] 308 Close the inlet of the accumulator

[0122] 310 Open the outlet of the accumulator

[0123] 312 discharges the fluid from the accumulator.

[0124] E Exhaust location area

[0125] F Filter Position

[0126] Q Melt volume flow rate

[0127] ΔQ volume flow range

[0128] R Recoil Position Area

[0129] S screen replacement position

[0130] SE accumulator empty position.

Claims

1. A filtering device (2) for filtering fluid, in particular liquefied plastic, comprising: A housing (4) having a container (6) for receiving a screen carrier (14) and having a fluid inlet channel (8) and a fluid outlet channel (10); a screen carrier (14) movably received within the container (6) along a longitudinal axis (12) and having a screen carrier inlet (16), a screen carrier outlet (18) and a cavity (20) for receiving a filter element (22), wherein the cavity (20) is in fluid communication with both the screen carrier inlet (16) and the screen carrier outlet (18), and The screen carrier (14) is movable from a screen replacement position (S) via an exhaust position area (E) to a filtering position (F), It is characterized by an accumulator (24a-c), which can be fluidically connected to the screen carrier inlet (16) and / or the screen carrier outlet (18), and the accumulator is configured to store fluid supplied via the screen carrier inlet (16) and / or the screen carrier outlet (18), and to control the supply of fluid to the accumulator (24a-c) so that the volume flow rate (Q) of the melt, in particular the volume flow rate (Q) of the melt leaving the filtering device (2) and being supplied to downstream system components, is maintained within a definable range (ΔQ) of volume flow rate.

2. The filter device (2) according to claim 1, in, The filter device (2) has a control unit (26) which is configured to control the supply of fluid into the accumulators (24a-c) so that the volume flow rate (Q) of the melt, in particular the volume flow rate (Q) of the melt leaving the filter device (2) and being supplied to downstream system components, remains within a definable range (ΔQ) of volume flow rate.

3. The filter device (2) according to claim 2, in, The volume flow (Q) of the melt is determined by a pressure sensor (28), which is preferably arranged in the filter device (2), in particular in the fluid outlet channel (10).

4. The filter device (2) according to any one of the preceding claims, in, The accumulators (24a-c) are arranged in a separate housing (30) or in the housing (4).

5. The filter device (2) according to any one of the preceding claims, in, The housing (4) has an accumulator connection passage (32) which fluidly connects the screen carrier inlet (16) to an accumulator inlet (25) depending on the position of the screen carrier (14) relative to the housing (4).

6. The filter device (2) according to claim 5, in, The screen carrier (14) is vented in the venting location area (E) by supplying fluid via the fluid outlet channel (10), and Wherein the accumulator connecting channel (32) provides fluid communication between the screen carrier inlet (16) and the inlet (25) of the accumulator (24a-c) in the exhaust position area (E).

7. The filter device (2) according to claim 5 or 6, in, The screen carrier (14) can be brought into a backflushing position area (R) in which a backflushing fluid is supplied to the filter element (22) from a clean side (36) of the filter element (22) to a dirty side (34) of the filter element (22), Wherein the accumulator connecting channel (32) provides fluid communication between the screen carrier inlet (16) and the inlet (25) of the accumulator (24a-c) in the backflushing position region (R).

8. The filter device (2) according to any one of the preceding claims, in, The screen carrier (14) has an outlet passage (38) which provides fluid communication between the reservoir connecting passage (32) and the surrounding environment (40) of the filter device (2) when the screen carrier (14) is in the reservoir emptying position (SE), so that the fluid received in the reservoir (24a-c) can be discharged to the surrounding environment (40), and Therein, the accumulator connecting channel (32) is disconnected from the screen carrier inlet (16) in the accumulator emptying position (SE).

9. The filter device (2) according to claim 8, in, The accumulator emptying position (SE) of the screen carrier (14) matches the filtering position (F) of the screen carrier (14).

10. The filter device (2) according to any one of the preceding claims, in, The accumulator (24a) is designed as a piston accumulator (42).

11. The filter device (2) according to claim 10, in, The piston accumulator (42) has an accumulator chamber (44) and a piston (46) which is arranged in the accumulator chamber (44) and can be driven by an actuator (48), and Therein, the supply of the fluid into the accumulator (24) is controlled by the piston (46).

12. The filter device (2) according to claim 11, in, The actuator (48) is implemented as a lifting cylinder (50) which is configured to drive the piston (46) along a longitudinal axis (54) of the accumulator.

13. The filter device (2) according to claim 11, in, The actuator (48) is implemented as a rotary lift cylinder (52) which is configured to rotationally drive the piston (46) along the longitudinal axis (54) of the accumulator and within the accumulator chamber (44). The piston (46) has a longitudinal groove (56) which interacts with both a piston accumulator inlet (57) and a piston accumulator outlet (58) so as to release fluid communication with the piston accumulator inlet (57) or the piston accumulator outlet (58) depending on the rotational position of the piston (46).

14. The filter device (2) according to claim 10, in, The piston accumulator (42) has a piston accumulator outlet (58) and a valve (60) having a valve pin (62), The piston accumulator outlet (58) is blocked or released depending on the position of the valve pin (62) relative to the piston accumulator outlet (58).

15. The filter device (2) according to any one of the preceding claims, in, The accumulator (24a) has a control valve (64) connected to the accumulator chamber (44) and configured to apply pressure to or exhaust gas from the accumulator chamber (44).

16. The filter device (2) according to any one of the preceding claims, in, The screen carrier (14) is a first screen carrier (14), and wherein the filter device (2) has at least a second screen carrier (66) which is movably received in the housing (4) and has a second screen carrier inlet (68), The housing (4) has at least a second accumulator connecting channel (76) which fluidly connects the second screen carrier inlet (68) to the inlet (25) of the accumulator (24a-c), depending on the position of the second screen carrier (66) relative to the housing (4).

17. A method (100) for venting a filter device (2), in particular a filter device (2) according to any one of the preceding claims, comprising the following steps: The screen carrier (14) of the filter device (2) is moved (102) into the exhaust position area (E), supplying (104) exhaust fluid via the fluid outlet passage (10) of the filter device (2) such that air in the cavity (20) of the screen carrier (14) is exhausted toward the screen carrier inlet (16), The exhausted air and / or exhaust fluid is supplied (106) from the screen carrier inlet (16) to an accumulator (24a-c), wherein the supply of fluid to the accumulator (24a-c) is controlled so that the volume flow rate (Q) of the melt, in particular the volume flow rate (Q) of the melt leaving the filtering device (2) and being supplied to downstream system components, is maintained within a definable range (ΔQ) of volume flow rate.

18. A method (200) for venting a filter device (2), in particular a filter device (2) according to any one of the preceding claims, comprising the following steps: The screen carrier (14) of the filter device (2) is moved (202) into the exhaust position area (E), supplying (204) exhaust fluid via the fluid inlet passage (8) of the filter device (2) such that air in at least one cavity (20) of the screen carrier (14) is exhausted toward the screen carrier outlet (18), The exhausted air and / or exhaust fluid is supplied (206) from the screen carrier outlet (18) to an accumulator (24a-c), wherein the supply of the fluid to the accumulator (24a-c) is controlled so that the volume flow rate (Q) of the melt, in particular the volume flow rate (Q) of the melt leaving the filtering device (2) and being supplied to downstream system components, is maintained within a definable range (ΔQ) of volume flow rate.

19. A method (300) for backflushing a filter device (2), in particular a filter device (2) according to any one of the preceding claims, comprising the following steps: The screen carrier (14) of the filter device (2) is moved (302) to the backflushing position region (RS), supplying (304) a backflushing fluid via a fluid outlet channel (10) of the filter device (2) such that the backflushing fluid is supplied to the filter element (22) from the clean side (36) to the dirty side (34) of the filter element (22) and the backflushing fluid is pressed toward a screen carrier inlet (16), The backflushing fluid is supplied (306) from the screen carrier inlet (16) to an accumulator (24a-c), wherein the supply of the fluid into the accumulator (24a-c) is controlled so that the volume flow rate (Q) of the melt, in particular the volume flow rate (Q) of the melt leaving the filtering device (2) and being supplied to downstream system components, is maintained within a definable range (ΔQ) of volume flow rate.

20. The method (100, 200, 300) according to any one of claims 17 to 19, comprising the following steps: closing (108, 208, 308) the inlet (25) of the accumulator (24a-c), opening (110, 210, 310) the outlet (27) of the accumulator (24a-c), Fluid contained in the accumulator (24a-c) is discharged (112, 212, 312) out of the accumulator (24a-c) via the outlet (27).

21. The method (100) according to claim 20, The steps of closing (108) the inlet (25) and opening (110) the outlet (27) are performed by moving the screen carrier (14) to an accumulator empty position (SE), in which an accumulator connecting channel (32) provides fluid communication between the accumulator (24a) and the surrounding environment (40) of the filter device (2), and the screen carrier inlet (68) is disconnected.

22. A filtering device for filtering fluid, in particular liquefied plastic, comprising: a housing having a receptacle for receiving the screen carrier and having a fluid inlet passage and a fluid outlet passage; a screen carrier movably received within the container along a longitudinal axis and having a screen carrier inlet, a screen carrier outlet, and a cavity for receiving a filter element, wherein the cavity is in fluid communication with both the screen carrier inlet and the screen carrier outlet; The screen carrier is movable from a screen changing position (S) via an exhaust position area to a filtering position (F); as well as An accumulator, which can be fluidly connected to the screen carrier inlet and / or the screen carrier outlet, and the accumulator is configured to store fluid supplied via the screen carrier inlet and / or the screen carrier outlet, and to control the supply of the fluid into the accumulator so that the volume flow rate (Q) of the melt, in particular the volume flow rate (Q) of the melt leaving the filtering device and being supplied to downstream system components, is maintained within a definable range (ΔQ) of volume flow rate.

23. The filtering device according to claim 22, in, The filter device has a control unit which is configured to control the supply of fluid into the accumulator so that the volume flow rate (Q) of the melt, in particular the volume flow rate (Q) of the melt leaving the filter device and being supplied to downstream system components, remains within a definable range (ΔQ) of volume flow rates.

24. The filtering device according to claim 23, in, The volume flow (Q) of the melt is determined by a pressure sensor which is preferably arranged in the filter device, in particular in the fluid outlet channel.

25. The filtering device according to claim 22, in, The accumulator is arranged in a separate housing or in the housing.

26. The filtering device according to claim 22, in, The housing has an accumulator connection passage that fluidly connects the screen carrier inlet to an accumulator inlet depending on the position of the screen carrier relative to the housing.

27. The filtering device according to claim 26, in, The screen carrier is vented in the venting location area by supplying fluid via the fluid outlet channel, and Therein, the accumulator connecting passage provides fluid communication between the screen carrier inlet and the inlet of the accumulator in the exhaust position area.

28. The filtering device according to claim 26, in, The screen carrier can be brought into a backflushing position area (R) in which backflushing fluid is supplied to the filter element from the clean side of the filter element to the dirty side of the filter element, Therein, the accumulator connecting channel provides fluid communication between the screen carrier inlet and the inlet of the accumulator in the backflushing position region (R).

29. The filtering device according to claim 22, in, The screen carrier has an outlet passage that provides fluid communication between the reservoir connection passage and the surrounding environment of the filter device when the screen carrier is in the reservoir empty position (SE), so that fluid received in the reservoir can be discharged to the surrounding environment, and Therein, the accumulator connecting channel is disconnected from the screen carrier inlet in the accumulator emptying position (SE).

30. The filtering device according to claim 29, in, The accumulator emptying position (SE) of the screen carrier matches the filtering position (F) of the screen carrier.

31. The filtering device according to claim 22, in, The accumulator is designed as a piston accumulator.

32. The filtering device according to claim 31, in, The piston accumulator has an accumulator chamber and a piston which is arranged in the accumulator chamber and can be driven by an actuator, and The supply of the fluid into the accumulator is controlled by the piston.

33. The filtering device according to claim 32, in, The actuator is implemented as a lift cylinder configured to drive the piston along a longitudinal axis of the accumulator.

34. The filtering device according to claim 32, in, The actuator is implemented as a rotary lift cylinder configured to rotationally drive the piston along the longitudinal axis of the accumulator and within the accumulator chamber, Therein, the piston has a longitudinal groove which interacts with both a piston accumulator inlet and a piston accumulator outlet such that fluid communication with the piston accumulator inlet or the piston accumulator outlet is released depending on the rotational position of the piston.

35. The filtering device according to claim 31, in, The piston accumulator has a piston accumulator outlet and a valve having a valve pin, Wherein, the piston accumulator outlet is blocked or released according to the position of the valve pin relative to the piston accumulator outlet.

36. The filtering device according to claim 32, in, The accumulator has a control valve connected to the accumulator chamber and configured to apply pressure to or exhaust gas from the accumulator chamber.

37. The filtering device according to claim 22, in, the screen carrier is a first screen carrier, and wherein the filter device has at least a second screen carrier movably received in the housing and having a second screen carrier inlet, Wherein the housing has at least a second accumulator connecting passage which fluidly connects the second screen carrier inlet to the inlet of the accumulator depending on the position of the second screen carrier relative to the housing.

38. A method for venting a filter device, in particular a filter device according to claim 22, comprising: Moving the screen carrier of the filter device into the exhaust position area, supplying exhaust fluid through the fluid outlet passage of the filter device so that air in the cavity of the screen carrier is exhausted toward the screen carrier inlet, The exhausted air and / or exhaust fluid is supplied from the screen carrier inlet to an accumulator, wherein the supply of the fluid into the accumulator is controlled so that the volume flow rate (Q) of the melt, in particular the volume flow rate (Q) of the melt leaving the filtering device and being supplied to downstream system components, is maintained within a definable range (ΔQ) of volume flow rates.

39. A method for venting a filter device, in particular a filter device according to claim 22, comprising: Moving the screen carrier of the filter device into the exhaust position area, supplying exhaust fluid through the fluid inlet passage of the filter device so that air in at least one cavity of the screen carrier is exhausted toward a screen carrier outlet, The exhausted air and / or exhaust fluid is supplied from the screen carrier outlet to an accumulator, wherein the supply of the fluid into the accumulator is controlled so that the volume flow rate (Q) of the melt, in particular the volume flow rate (Q) of the melt leaving the filtering device and being supplied to downstream system components, is maintained within a definable range (ΔQ) of volume flow rates.

40. A method for backflushing a filter device, in particular a filter device according to claim 22, comprising: Move the screen carrier of the filter device to the backflushing position area (RS), supplying a backflushing fluid via a fluid outlet channel of the filter device such that the backflushing fluid is supplied to the filter element from a clean side to a dirty side of the filter element and the backflushing fluid is pressed toward a screen carrier inlet, The backflushing fluid is supplied from the screen carrier inlet to an accumulator, wherein the supply of the fluid into the accumulator is controlled so that the volume flow rate (Q) of the melt, in particular the volume flow rate (Q) of the melt leaving the filtering device and being supplied to downstream system components, is maintained within a definable range (ΔQ) of volume flow rates.

41. A method according to any one of claims 38 to 40, comprising: closing the inlet of the accumulator, opening an outlet of the accumulator; The fluid contained in the accumulator is discharged out of the accumulator via the outlet.

42. The method according to claim 41, in, Closing the inlet and opening the outlet is performed by moving the screen carrier to an accumulator empty position (SE) in which an accumulator connection channel provides fluid communication between the accumulator and the surrounding environment of the filter device and the screen carrier inlet is disconnected.

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