Filtration device for filtering fluid, and gas venting and backflushing methods

Abstract

The device may include a receptacle for receiving the screen carrier and a housing with a fluid inlet and a fluid outlet. Additionally, the device may include a screen carrier movably received within the receptacle, the screen carrier having a screen carrier inlet, a screen carrier outlet, and a cavity for receiving the filter element, the cavity being in fluid communication with the screen carrier inlet and the screen carrier outlet. The screen carrier may be moved from the screen changing position (S) to the filtering position (F) via the degassing position area. Furthermore, the device may include an accumulator fluidly connectable to the screen carrier inlet and / or the screen carrier outlet, the accumulator configured to store fluid delivered via the screen carrier inlet and / or the screen carrier outlet and to control delivery of fluid into the accumulator.

Description

[Technical Field]

[0001] The present invention relates to a filtration device for filtering fluids, in particular liquefied plastics, comprising a housing with a receptacle for receiving a screen carrier and with a fluid inlet channel and a fluid outlet channel, and a screen carrier movably received in 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 changing position to a filtering position via a degassing position area. The present invention also relates to a method for this filtration device.

[0002] [Citation of Related Applications] This application is a claim of German Patent Application No. 102022124308.7, filed Sep. 21, 2000, which is incorporated by reference and incorporated herein in its entirety for all purposes. [Background technology]

[0003] Filtration devices are used in plastic processing machines, for example, when the purity of the plastic being processed must meet strict requirements. These plastic processing machines are typically located between an extruder, which melts and conveys the plastic, and an applicator. Such filtration devices for filtering fluids, particularly liquefied plastics, and methods for operating such filtration devices are known in the prior art. The filtration device comprises a screen carrier that houses a filtering element (also called a screen).

[0004] Such filtering elements typically must be replaced or cleaned after they have been in operation for some time. To replace the filter element, the screen carrier is moved from a filtering position, also called a production position, to a screen replacement position, where the filter element can be accessed and replaced.

[0005] Once the filter element has been replaced, it must be returned to the production process. The fundamental challenge this presents is that the internal space of the screen carrier, called the cavity, typically fills with air after the screen replacement, and it is essential to prevent air from being introduced into the plastic fluid stream (steady flow). After the screen replacement, the screen carrier is first moved to a venting position area, where the liquefied plastic flows into the screen cavity and pushes the air contained therein out through the venting channels.

[0006] In most cases, the plastic used for backflushing is removed from the plastic fluid stream to be filtered. This aspect also plays a role in backflushing a filter element, in which a clean or purified plastic melt is used to backflush the filter element in the direction opposite to the filtration direction in order to clean it. The plastic used for backflushing is also removed in most cases in the form of a volumetric flow from the plastic fluid stream to be filtered. This volumetric flow is generally regulated and kept within limits by changing the pressure level. However, this regulation of the pressure level has limitations. If the plastic fluid stream degasses or backflushes too quickly, this can have a negative impact on the volumetric flow rate of the plastic and the system pressure. For example, when using a spinning nozzle, such pressure fluctuations can have a negative impact on the spinning process. Product quality may be impaired or the spun plastic may even break.

[0007] To mitigate or even completely prevent these negative consequences, it is known in the prior art to open venting / backflushing channels through which venting or backflushing fluids are delivered, with the aim of controlling the overall system pressure, albeit only partially. However, this approach faces limitations when the system pressure is very high or the viscosity of the melt is very low. It may not be possible to guarantee the prevention of pressure fluctuations. Depending on the properties of the melt, it may also be necessary to open the backflushing channels only slightly, i.e., with a small opening cross-section. However, this can result in relatively large contaminant particles clogging this opening cross-section, which also means that the pressure cannot be regulated in an ideal manner. Summary of the Invention [Problem to be solved by the invention]

[0008] Against this background, the object of the present invention is to develop a filtration apparatus and method of the type described at the beginning in such a way as to eliminate as much as possible the drawbacks identified in the prior art. Specifically, the object of the present invention is to devise a filtration apparatus and method in which the volumetric flow rate of melt leaving the filtration apparatus and the overall system pressure remain as constant as possible during a screen replacement operation or a backflushing of a filter element, while reducing the overall system complexity of the filtration apparatus. [Means for solving the problem]

[0009] According to the invention, this object is achieved by a filtering device of the type mentioned in the introduction, characterized in that an accumulator is fluidly connectable to the screen carrier inlet and / or the screen carrier outlet, the accumulator being configured to store fluid fed via the screen carrier inlet and / or the screen carrier outlet and to control the feeding of fluid into the accumulator in such a way that the volumetric flow rate of the melt, in particular the volumetric flow rate of the melt leaving the filtering device and fed to a downstream system component, remains within a definable volumetric flow rate range.

[0010] The present invention takes advantage of the discovery that by controlling how fluid is delivered to the accumulator, either in the form of volumetric or mass flow, the cavity can be reliably vented, even at high outlet pressures and low viscosities. Typically, the fluid used for venting or backflushing is delivered to and contained in the accumulator, and then released to the environment after venting or backflushing. By controlling how fluid is delivered to the accumulator, the overall system pressure can be kept within precisely definable limits and a constant volumetric flow rate of melt exiting the filter and being delivered to downstream system components can be ensured. Thus, in a sense, the accumulator functions as a hydraulic arrester when the cavity is vented or backflushed, resulting in a finely metered flow of material through the cavity. The filter of the present invention is also suitable for a wide pressure and viscosity range for the melt to be processed. The accumulator is preferably one in which the throughflow is non-permanent. A downstream system component is understood to be a component located downstream from the filter. Such a component may be a forming tool.

[0011] The present invention is advantageously configured by a filtration device having a control unit configured to control the feeding of fluid into the accumulator in such a way that the volumetric flow rate of the melt, particularly the volumetric flow rate of the melt leaving the filtration device and being sent to downstream system components, remains within a predeterminable volumetric flow rate range. With the aid of the control unit of the present invention, the feeding of fluid into the accumulator, e.g., at a mass flow rate or a volumetric flow rate, is controlled in such a way that the volumetric flow rate of the melt remains within the predeterminable volumetric flow rate range. As a result, the system pressure and the overall system pressure remain within the predeterminable pressure range.

[0012] According to a preferred embodiment, the change in the volumetric flow rate of the melt is alternatively determined by a pressure sensor, preferably arranged in the filtration device, in particular in the fluid outlet channel. The volumetric flow rate 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 regarding the volumetric flow rate of the melt through the filtration device or the system as a whole, since a change in the volumetric flow rate necessarily results in a change in pressure. According to one embodiment, the pressure is not necessarily measured in the filtration device, but can also be measured anywhere else convenient in the system. In one embodiment, the pressure is measured downstream of the filtration device and at the inlet side of the forming tool or downstream pressure generator.

[0013] The present invention is retrofittable by locating the accumulators in a separate housing or in the screen carrier housing. By locating the accumulators in a separate housing, the life of existing equipment can be extended with the respective accumulators without the need for costly or time-consuming modifications. When the accumulators are installed directly in the housing of the filtering device, a particularly compact filtering device can be specified.

[0014] According to another embodiment, the housing has an accumulator connection channel fluidly connecting the screen carrier inlet to the accumulator inlet depending on the position of the screen carrier relative to the housing. The screen carrier is preferably degassed in the degassing position area by directing fluid through the fluid outlet channel, and the accumulator connection channel is capable of fluidly connecting the screen carrier inlet and the accumulator inlet in the degassing position area.

[0015] Thus, the fluid used for venting, particularly the plastic melt, as well as any air pockets, may reach the accumulator via the accumulator connecting channel and be received within the accumulator.

[0016] The present invention is advantageously configured by allowing the screen carrier to be moved to a backflushing position where backflushing fluid is delivered to the filter element from the clean side of the filter element to the dirt side of the filter element, and the accumulator connecting channel fluidly connects the screen carrier inlet to the accumulator inlet in the backflushing position. In this way, the fluid used for backflushing, which typically contains impurities already in the screen, can also be delivered and placed into the accumulator.

[0017] The screen carrier preferably has an outlet channel that fluidly connects the accumulator connecting channel to the surroundings of the filtration device when the screen carrier is in the accumulator drain position, thereby allowing fluid received in the accumulator to be discharged to the surroundings, and the accumulator connecting channel is disconnected from the screen carrier inlet in the accumulator drain position, thereby allowing the accumulator to be emptied towards the surroundings of the filtration device, where the accumulator connecting channel is disconnected from the screen carrier inlet, thereby preventing fluid contained in the accumulator from being returned to the system.

[0018] According to a preferred embodiment, the accumulator drain position of the screen carrier coincides with the filtering position of the screen carrier. This means that after the screen carrier has vented or backflushed the cavity by moving it to the filtering position, the screen carrier performs its filtering function, and at the same time, in the filtering position that coincides with the accumulator drain position, the accumulator is connected to the periphery of the filtering device via the outlet channel, so that in the filtering position, fluid can be discharged from the accumulator to the periphery. In other words, functional integration is therefore achieved here: by moving the screen carrier, the screen carrier is brought to the filtering position, and at the same time the accumulator is connected to the periphery. In this configuration example, no additional valves or the like are required.

[0019] The present invention is advantageously configured by the accumulator being embodied as a piston accumulator. The piston accumulator preferably has an accumulator chamber and a piston arranged therein, which can be driven by an actuator, and the feeding of fluid into the accumulator is controlled by the piston. The actuator is preferably embodied as a lift cylinder configured to drive the piston along the longitudinal axis of the accumulator. In this embodiment, the mass or volume flow rate fed to the accumulator is thus controlled by driving the piston along the longitudinal axis of the accumulator. At the same time, the piston can be used to expel the fluid received in the accumulator from the accumulator, for example, towards the periphery of the filtering location, by driving the piston in the opposite direction.

[0020] According to an alternative embodiment, the actuator is embodied as a rotary lift cylinder configured to drive a piston rotationally along the longitudinal axis of the accumulator and in the accumulator chamber, the piston having a longitudinal groove that interacts with the piston accumulator inlet or outlet in such a way that fluid communication with the piston accumulator inlet or outlet is released according to the rotational position of the piston. The piston thus performs in a sense two functions: firstly, it allows a controlled and well-metered introduction of fluid into the accumulator, and secondly, its movement in the opposite direction allows it to remove fluid from the accumulator chamber, while at the same time, due to the rotation of the piston, either the piston accumulator inlet or the piston accumulator outlet is opened, which means that no additional valves are needed in the region of the inlet or outlet.

[0021] According to another variant embodiment, the piston accumulator has a valve with a piston accumulator outlet and a valve pin, the piston accumulator outlet being blocked or opened according to 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 or empty the accumulator chamber. In this way, before using the accumulator to vent or backflush, it is possible to prepare the accumulator for its respective use.

[0022] The present invention is modified by the fact that the screen carrier is a first screen carrier, the filtering device has at least a second screen carrier movably received in the housing and having a second screen carrier inlet, and the housing has at least a second accumulator connection channel fluidly connecting the second screen carrier inlet to the accumulator inlet depending on the position of the second screen carrier relative to the housing. By providing additional screen carriers, it is possible to provide the filtering device with permanent operability. For example, while the first screen carrier is in a venting or backflushing position, the other screen carrier continues to allow filtering to occur, and vice versa. According to a preferred embodiment, the filtering device has three or more screen carriers, which are embodied similarly to two of the first screen carriers and movably received in the housing. Each screen carrier may have one or more cavities.

[0023] The present invention has been described above with reference to a filtration device. In a second aspect, the present invention relates to a method for venting a filtration device, in particular a filtration device according to any one of the above-described embodiments. According to the present invention, the method comprises the steps of moving a screen carrier of the filtration device to a venting position area, feeding a venting fluid through a fluid outlet channel of the filtration device so that air in the cavity of the screen carrier is displaced towards the screen carrier inlet, and feeding the displaced air and / or venting fluid from the screen carrier inlet to an accumulator, wherein the feeding of the fluid into the accumulator is controlled in such a way that the volumetric flow rate of the melt, in particular the volumetric flow rate of the melt leaving the filtration device and being fed to a downstream system component, remains within a definable volumetric flow range. Thus, the system pressure remains within definable limits when the screen carrier is vented via the screen carrier outlet.

[0024] In a third aspect, the present invention relates to a method for degassing a filtration device, in particular a filtration device according to any one of the above-described embodiments. The method comprises the steps of moving a screen carrier of the filtration device to a degassing position area, feeding a degassing fluid through a fluid outlet channel of the filtration device so that air in at least one cavity of the screen carrier is displaced toward the screen carrier inlet, and feeding the displaced air and / or degassing fluid from the screen carrier outlet to an accumulator, wherein the feeding of the fluid into the accumulator is controlled in such a way that the volumetric flow rate of the melt, in particular the volumetric flow rate of the melt leaving the filtration device and being sent to a downstream system component, remains within a predeterminable volumetric flow rate range. The method according to the third aspect is an alternative solution to the method according to the second aspect, i.e., in the method according to the third aspect, the degassing fluid is fed through the fluid inlet channel and 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 filtration device and the method according to the second aspect of the present invention. In this regard, reference should be made to the above findings, which are incorporated by reference and whose contents are made part of this specification.

[0025] In a fourth aspect, the present invention relates to a method for backflushing a filtration device, in particular a filtration device according to any one of the above embodiments, comprising the steps of moving a screen carrier of the filtration device to a backflushing position area, directing a backflushing fluid through a fluid outlet channel of the filtration device so that the backflushing fluid is delivered to the filter element from a clean side of the filter element to a dirt side of the filter element, and directing the backflushed fluid from the screen carrier inlet to an accumulator, wherein the delivery of the fluid into the accumulator is controlled in such a way that the volumetric flow rate of the melt, in particular the volumetric flow rate of the melt leaving the filtration device and delivered to a downstream system component, remains within a definable volumetric flow range.

[0026] This ensures that even during backflushing, the volumetric flow rate of melt leaving the filtration device and being sent to downstream system components, and therefore the overall system pressure, remains within a definable volumetric flow rate range, thus ensuring the desired product quality over a wide operating pressure and viscosity range. The method of the fourth aspect utilizes the same advantages and preferred embodiments as the filtration device and methods of the second and third aspects of the present invention. In this regard, reference should be made to the above teachings, which are incorporated by reference and made a part of this specification.

[0027] The present invention is modified by including the steps of closing an inlet of the accumulator, opening an outlet of the accumulator, and discharging fluid contained within the accumulator from the accumulator via the outlet.

[0028] The present invention is further modified by having the steps of closing the accumulator inlet and opening the accumulator outlet performed by moving the screen carrier to an accumulator drain position where the accumulator connecting channel is in fluid communication with the accumulator and the periphery of the filtration device and the screen carrier inlet is disconnected, preventing fluid from entering the process as it is discharged from the accumulator.

[0029] Further features and advantages of the invention result from the appended claims and the following description, in which embodiments are explained in detail with reference to the schematic drawings. [Brief explanation of the drawings]

[0030] [Figure 1a] 1 is a diagram showing a first embodiment of a filtering device of the present invention. [Figure 1b] FIG. 1b shows detail “X” of the filtration device of FIG. 1a, specifically the melt accumulator. [Figure 2]FIG. 1 illustrates an embodiment of a filtration device of the present invention in a filter or accumulator drain position. [Figure 3] 1 shows an embodiment of a filtration device of the present invention in a venting position area. [Figure 4] 1 shows an embodiment of a filtration device of the present invention in a venting position area. [Figure 5] 1 shows an embodiment of a filtration device of the present invention in a backflushing position. [Figure 6] 1A-1C illustrate an embodiment of a filtration device of the present invention in an accumulator drain position or filtration device. [Figure 7] 1A-1C illustrate an embodiment of a filtration device of the present invention in an accumulator drain position or filtration device. [Figure 8] 8A, 8B, and 8C are cross-sectional views of alternative embodiments of the accumulator of the present invention. [Figure 9] 9a and 9b are cross-sectional views of alternative embodiments of the accumulator of the present invention. [Figure 10] FIG. 1 is a block diagram of the method of the present invention. [Figure 11] FIG. 1 is a block diagram of the method of the present invention. [Figure 12] FIG. 1 is a block diagram of the method of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0031] 1-7 show a first embodiment of a filtering device 2. The filtering device 2 is adapted to filter fluids, particularly liquefied plastics. The filtering device 2 has a housing 4. The housing 4 has a receptacle 6 for receiving a screen carrier, as well as a fluid inlet channel 8 and a fluid outlet channel 10. A screen carrier 14 is movably received in the receptacle 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 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. The screen carrier 14 can be moved from a filtering position F shown in FIG. 2 to a screen change position S shown in FIG. 1a, and to a degassing position or degassing position area E shown in FIGS. 3 and 4.

[0032] The filtering device 2 further comprises accumulators 24a-24c, which are fluidly connectable to the screen carrier inlet 16 and are adapted to store the fluid fed via the screen carrier inlet 16 and to control the feeding of the fluid into the accumulators 24. According to an alternative embodiment not shown, it is also conceivable that the accumulators are fluidly connectable to the screen carrier outlet 18 and are adapted to store the fluid fed via the screen carrier outlet 18 and to control the feeding of the fluid into the accumulators 24 accordingly.

[0033] The filtering device 2 includes a control unit 26. The control unit 26 is configured to control the feeding of fluid into the accumulator 24 so that the volumetric melt flow rate Q, particularly the volumetric melt flow rate Q exiting the filtering device 2 and being sent to a downstream system component, remains within a definable volumetric flow rate range ΔQ. Changes in the volumetric melt flow rate Q are preferably determined indirectly, particularly alternatively, by a pressure sensor 28 disposed in the fluid outlet channel 10. In the illustrated embodiment, the accumulator 24 is disposed in a separate housing 30, which is coupled to the housing 4 of the filtering device 2. The housing 4 includes an accumulator coupling channel 32 that fluidly couples the screen carrier inlet 16 to the accumulator inlet 57 depending on the position of the screen carrier inlet 14 relative to the housing 4. The screen carrier 14 is driven by a screen carrier drive means 78. The screen carrier 14 further includes a degassing groove 80. At least one housing vent groove 81 (also called collection groove) is disposed in the housing 4. The filter element (also called screen) 22 is held in place by a screen support plate 82 and a screen retainer 84.

[0034] 3 and 4, the screen carrier 14 is vented by directing fluid through the fluid outlet channel 10. In the vent position region E, the accumulator connection channel 32 may provide fluid communication between the screen carrier inlet 16 and the outlet 27 of the accumulator 24.

[0035] 5, the screen carrier 14 can also be moved to a backflushing position region R. In the backflushing position region R, backflushing fluid is directed to the filter element 22 from the clean side 36 of the filter element 22 to the dirt side 34 of the filter element 22. In the backflushing position region R, the accumulator connecting channel 32 can fluidly connect the screen carrier inlet 16 to the inlet 25 of the accumulator 24.

[0036] The screen carrier 14 further includes an outlet channel 38. In an accumulator drain position (emptying position) SE, as shown in FIG. 6 for example, the outlet channel 38 may fluidly connect the accumulator connecting channel 32 to the periphery 40 of the filtering device 2, such that fluid received in the accumulator 24 may be discharged to the periphery 40. In the accumulator drain position SE, the accumulator connecting channel 32 is also disconnected from the screen carrier inlet 16. As shown in FIG. 2 or FIG. 6, the accumulator drain position SE of the screen carrier 14 coincides with the filtering position F of the screen carrier 14.

[0037] In the first embodiment of the filtering device 2 shown in FIGS. 1 to 7, the accumulator 24a is embodied as a piston accumulator 42. The piston accumulator 42 has an accumulator chamber 44 and a piston 46 arranged therein and drivable by an actuator 48. The position of the actuator 48 is measured by a position measuring device 19. The delivery of fluid into the accumulator 24, i.e., in particular the mass and volume flow rate, is controlled by the piston 46, in particular its translational movement. The actuator 48 is embodied as a lift cylinder 50. The lift cylinder 50 is configured to drive the piston 46 along the accumulator's longitudinal axis 54. As shown in detail in FIG. 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 or vent the accumulator chamber 44. 1a, the screen carrier 14 is a first screen carrier 14, and the filtering device 2 has a second screen carrier 66 movably received within the housing 4. As shown in FIG. 4, the screen carrier 66 has a second screen carrier inlet 68. In this regard, the housing 4 has at least a second accumulator coupling channel 76 that fluidly couples the second screen carrier inlet 68 to the inlet 25 of the accumulator 24a depending on the position of the second screen carrier 66 relative to the housing 4.

[0038] In the embodiment of accumulator 24b shown in Figures 8a-8c, actuator 48 is embodied as a rotary lift cylinder 52. Rotary lift cylinder 52 is configured to rotationally drive piston 46 along accumulator longitudinal axis 54 and within accumulator chamber 44. Piston 46 has a longitudinal groove 56 designed to interact with piston accumulator inlet 57 and piston accumulator outlet 58 in such a way that fluid communication with piston accumulator inlet 57 or piston accumulator outlet 58 is released depending on the rotational position of piston 46.

[0039] Figures 9a and 9b show another alternative embodiment of accumulator 24c. The accumulator 24c shown in these figures is embodied as a piston accumulator 42 having a piston accumulator outlet 58 and a valve 60 with a valve pin 62. The piston accumulator outlet 58 is opened or closed 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.

[0040] 10 illustrates one embodiment of a method 100 for venting a filter 2. The method includes step 102 of moving the screen carrier 14 of the filter 2 to a venting position area E, step 104 of directing a venting fluid through the fluid outlet channel 10 of the filter 2 to displace air in the screen carrier cavity 20 toward the screen carrier inlet 16, and step 106 of directing the displaced air and the venting fluid from the screen carrier inlet 16 to an accumulator 24, wherein the fluid delivery into the accumulator 24 is controlled in such a way that the volumetric flow rate Q of the melt, particularly the volumetric flow rate Q of the melt exiting the filter to a downstream system component, remains within a predeterminable volumetric flow range ΔQ, and the method embodiment further includes step 108 of closing the inlet 25 of the accumulator 24, step 110 of opening the outlet 27 of the accumulator 24, and step 112 of discharging the fluid in the accumulator 24 from the accumulator 24 via the outlet 27.

[0041] FIG. 11 shows an embodiment of a method 200 for degassing a filtration device, in particular a filtration device 2 according to any one of the embodiments described above. The method 200 includes step 202 of moving a screen carrier of the filtration device to a degassing position area; step 204 of directing a degassing fluid through a fluid outlet channel of the filtration device to displace air in at least one cavity of the screen carrier towards the screen carrier inlet; and step 206 of directing the displaced air and / or degassing fluid from the screen carrier outlet to an accumulator 24, wherein the fluid delivery into the accumulator 24 is controlled in such a manner that the volumetric flow rate Q of the melt, in particular the volumetric flow rate Q of the melt leaving the filtration device to a downstream system component, remains within a predeterminable volumetric flow rate range ΔQ; and the method embodiment further includes step 208 of closing the inlet 25 of the accumulator 24; step 210 of opening the outlet 27 of the accumulator 24; and step 212 of discharging the fluid in the accumulator 24 from the accumulator 24 via the outlet 27.

[0042] 12 illustrates one embodiment of a method 300 for backflushing a filtration device 2, particularly a filtration device 2 according to any one of the embodiments described above. The method 300 includes step 302 of moving the screen carrier 14 of the filtration device 2 to a backflushing position area RS, step 304 of directing backflushing fluid through the fluid outlet channel 10 of the filtration device 2 to direct the backflushing fluid against the filter element 22 from the clean side 36 to the dirt side 34 of the filter element 22 and to push the backflushed fluid towards the screen carrier inlet 16, step 305 of directing the backflushed fluid from the screen carrier inlet 16 to the accumulator 24, and step 306 of directing the backflushed fluid from the screen carrier inlet 16 to the accumulator 24. The method includes a step 306 of feeding fluid into the accumulator 24, wherein the feeding of fluid into the accumulator 24 is controlled in such a manner that the volumetric flow rate Q of the melt, particularly the volumetric flow rate Q of the melt exiting the filtration device and being fed to downstream system components, remains within a predeterminable volumetric flow rate range ΔQ, and the method embodiment further includes a step 308 of closing the inlet 25 of the accumulator 24, a step 310 of opening the outlet 27 of the accumulator 24, and a step 312 of discharging the fluid contained in the accumulator 24 from the accumulator 24 via the outlet 27.

[0043] Step 108 of closing the inlet 25 and step 110 of opening the outlet 27 are performed by moving the screen carrier 14 to the accumulator drain position SE, in which the accumulator connecting channel 32 fluidly connects the accumulator 24 to the periphery 40 of the filtration device 2 and the screen carrier inlet 16 is disconnected. [Explanation of symbols]

[0044] 2 Filtration device 4. Housing 6 Screen carrier receiver 8 Fluid Inlet Channel 10 fluid outlet channels 12 Longitudinal axis of receiver 14 (First) Screen Carrier 16 (First) screen carrier inlet 18 (First) Screen Carrier Outlet 19 Position measuring device 20 (first) cavity 22 filter element 24a~24c Accumulator 25 Accumulator inlet 26 Control Unit 27 Accumulator outlet 28 Pressure Sensor 30 Separate Housing 32 Reservoir connecting channel 34 Dirt side of filter element 36 Clean side of filter element 38 Exit Channel 40 Around the filtration device 42 Piston accumulator 44 Storage Chamber 46 Piston 48 Actuator 50 lift cylinder 52 Rotating lift cylinder 54 Longitudinal axis of accumulator 56 Longitudinal groove 57 Piston accumulator inlet 58 Piston accumulator outlet 60 valves 62 Valve pin 63 Valve pin passage 64 Control valve 66 Second Screen Carrier 68 Second screen carrier inlet 76 Second accumulator connection channel 78 Screen carrier drive means 80 Screen carrier gas vent groove 81 Housing gas vent groove 82 Screen support plate 84 Screen retainer 86 Actuator Outlet Valve 88 Outlet valve position detector 100 How to degas a filter 102 moving the screen carrier to the degassing position area 104. Passing degassing fluid through the fluid outlet channel 106. Sending the Displaced Air and / or Venting Fluid to an Accumulator 108. Step of closing the inlet of the accumulator 110 Step to open the outlet of the accumulator 112 Discharging fluid from the accumulator 200 How to degas a filter 202 moving the screen carrier to the degassing position area 204 Passing a degassing fluid through the fluid inlet channel 206. Sending the Displaced Air and / or Venting Fluid to an Accumulator 208 Step of closing the inlet of the accumulator 210 Step to open the outlet of the accumulator 212 Discharging fluid from the accumulator 300 How to backflush a filtration device 302 Step of moving the screen carrier to the back flush position area 304. Sending backflushing fluid through the fluid outlet channel of the filtration device. 306. Sending the backflushed fluid from the screen carrier inlet to an accumulator. 308 Step of closing the inlet of the accumulator 310 Step of opening the outlet of the accumulator 312 Discharging fluid from the accumulator E Gas vent area F filtration position Q Melt volume flow rate ΔQ volume flow range R Backflush position area S Screen replacement position SE Accumulator drain position (position to empty the accumulator)

Claims

1. A filtration device (2) for filtering fluids, in particular liquefied plastics, comprising: The device has a housing (4) with a receptacle (6) for receiving a screen carrier (14) and with a fluid inlet channel (8) and a fluid outlet channel (10), a screen carrier (14) movably received within the receptacle (6) along a longitudinal axis (12), the screen carrier (14) having a screen carrier inlet (16), a screen carrier outlet (18), and a cavity (20) for receiving a filter element (22), the cavity (20) being in fluid communication with the screen carrier inlet (16) and the screen carrier outlet (18); In a filtering device, the screen carrier (14) can be moved from a screen changing position (S) to a filtering position (F) via a degassing position area (E), 1. A filtering device, comprising: accumulators (24a-24c) fluidly connectable to the screen carrier inlet (16) and / or the screen carrier outlet (18), the accumulators (24a-24c) configured to store fluid channeled via the screen carrier inlet (16) and / or the screen carrier outlet (18) and to control the feeding of the fluid into the accumulators (24a-24c) in such a way that a volumetric flow rate (Q) of the melt, in particular the volumetric flow rate (Q) of the melt leaving the filtering device (2) and channeled to a downstream system component, remains within a definable volumetric flow rate range (ΔQ).

2. 2. The filtration device (2) according to claim 1, wherein the filtration device (2) is configured to control the fluid feed into the accumulators (24a-24c) in such a way that a volumetric flow rate (Q) of the melt, in particular a volumetric flow rate (Q) of the melt leaving the filtration device (2) and sent to a downstream system component, remains within a definable volumetric flow range (ΔQ).

3. 3. The filtration device (2) according to claim 2, wherein the volumetric flow rate (Q) of the melt is determined by a pressure sensor, preferably arranged in the filtration device (2), in particular in the fluid outlet channel (10).

4. The filtering device (2) according to claim 1, wherein the accumulators (24a-24c) are arranged in a separate housing (30) or in the housing (4).

5. 2. The filtering device (2) according to claim 1, wherein the housing (4) has an accumulator connection channel (32) that 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. 6. The filtration device (2) of claim 5, wherein the screen carrier (14) is degassed in the degassing position area (E) by sending fluid through the fluid outlet channel (10), and the accumulator connecting channel (32) fluidly connects the screen carrier inlet (16) with the inlets (25) of the accumulators (24a-24c) in the degassing position area (E).

7. The screen carrier (14) can be brought to a backflushing position area (R), in which backflushing fluid is directed against the filter element (22) from the clean side (36) of the filter element (22) to the dirt side (34) of the filter element (22); The filtering device (2) according to claim 5, wherein the accumulator connecting channel (32) fluidly connects the screen carrier inlet (16) and the inlet (25) of the accumulator (24a-24c) in the backflush position area (R).

8. 2. The filtration device (2) of claim 1, wherein the screen carrier (14) has an outlet channel (38) that fluidly connects the accumulator connecting channel (32) to a periphery (40) of the filtration device (2) when the screen carrier (14) is in an accumulator drain position (SE), such that fluid received in the accumulators (24a-24c) can be discharged to the periphery (40), and the accumulator connecting channel (32) is disconnected from the screen carrier inlet (16) in the accumulator drain position (SE).

9. 9. The filtering device (2) according to claim 8, wherein the accumulator drain position (SE) of the screen carrier (14) coincides with the filtering position (F) of the screen carrier (14).

10. 2. The filtering device (2) of claim 1, wherein the accumulator (24a) is embodied as a piston accumulator (42).

11. 11. The filtering device (2) of claim 10, wherein the piston accumulator (42) has an accumulator chamber (44) and a piston (46) disposed within the accumulator chamber (44), the piston (46) being actuable by an actuator (48), and the delivery of the fluid into the accumulator (24) being controlled by the piston (46).

12. 12. The filtering device (2) of claim 11, wherein the actuator (48) is embodied as a lift cylinder (50) configured to drive the piston (46) along the longitudinal axis (54) of the accumulator.

13. 12. The filtering device (2) of claim 11, wherein the actuator (48) is embodied as a rotary lift cylinder (52) configured to rotationally drive the piston (46) along the longitudinal axis (54) of the accumulator and within the accumulator chamber (44), the piston (46) having a longitudinal groove (56) interacting with the piston accumulator inlet (57) or the piston accumulator outlet (58) in such a way 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).

14. 11. The filtering device (2) of claim 10, wherein the piston accumulator (42) has a valve (60) with a piston accumulator outlet (58) and a valve pin (62), the piston accumulator outlet (58) being blocked or opened depending on the position of the valve pin (62) relative to the piston accumulator outlet (58).

15. 2. The filtering device (2) of claim 1, wherein the accumulator (24a) comprises a control valve (64) connected to the accumulator chamber (44) and configured to apply pressure to the accumulator chamber (44) or vent the accumulator chamber (44).

16. The screen carrier (14) is a first screen carrier (14), and the filtering device (2) has at least a second screen carrier (66) movably received within the housing (4) and having a second screen carrier inlet (68); 2. The filtering device (2) according to claim 1, wherein the housing (4) has a second accumulator connection channel (76) fluidly connecting the second screen carrier inlet (68) to the inlet (25) of the accumulator (24a-24c) depending at least on the position of the second screen carrier (66) relative to the housing (4).

17. A method (100) for degassing a filtration device (2), in particular a filtration device (2) according to claim 1, comprising: moving (102) the screen carrier (14) of said filtering device (2) to a degassing position area (E); (104) directing a degassing fluid through the fluid outlet channel (10) of the filter device (2) so that air in the cavity (20) of the screen carrier (14) is displaced towards the screen carrier inlet (16); and routing (106) the displaced air and / or the degassing fluid from the screen carrier inlet (16) to an accumulator (24a-24c), wherein the routing of the fluid into the accumulator (24a-24c) is controlled in such a way that a volumetric flow rate (Q) of the melt, in particular the volumetric flow rate (Q) of the melt exiting the filtration device (2) and being routed to a downstream system component, remains within a definable volumetric flow rate range (ΔQ).

18. A method (200) for degassing a filtration device (2), in particular a filtration device (2) according to claim 1, comprising: moving (202) the screen carrier (14) of said filtering device (2) to a degassing position area (E); (204) directing a degassing fluid through a fluid outlet channel (10) of the filtering device (2) to displace air in the at least one cavity (20) of the screen carrier (14) towards a screen carrier inlet (16); and routing (206) the displaced air and / or the degassing fluid from the screen carrier outlet (18) to an accumulator (24a-24c), wherein the routing of the fluid into the accumulator (24a-24c) is controlled in such a way that the volumetric flow rate (Q) of the melt, in particular the volumetric flow rate (Q) of the melt leaving the filtration device (2) and routed to a downstream system component, remains within a definable volumetric flow rate range (ΔQ).

19. A method (300) for degassing a filtration device (2), in particular a filtration device (2) according to claim 1, comprising: A step (302) of moving the screen carrier (14) of the filtering device (2) to a backflush position area (RS); directing (304) backflushing fluid through the fluid outlet channel (10) of the filtration device (2) such that the backflushing fluid is directed against the filter element (22) from the clean side (36) of the filter element (22) to the dirt side (34) of the filter element (22) and the backflushed fluid is pushed towards the screen carrier inlet (16); and sending (306) the backflushed fluid from the screen carrier inlet (16) to an accumulator (24a-24c), wherein the sending of the fluid into the accumulator (24a-24c) is controlled in such a way that a volumetric flow rate (Q) of the melt, in particular the volumetric flow rate (Q) of the melt exiting the filtration device (2) and being sent to a downstream system component, remains within a definable volumetric flow rate range (ΔQ).

20. a step (108, 208, 308) of closing the inlets (25) of the accumulators (24a-24c); a step (110, 210, 310) of opening the outlets (27) of the accumulators (24a-24c); and discharging (112, 212, 312) the fluid contained in the accumulator (24a-24c) from the accumulator (24a-24c) via the outlet (27).

21. 21. The method (100) of claim 20, wherein the steps (108, 208, 308) of closing the inlets (25) of the accumulators (24a-24c) and (110, 210, 310) of opening the outlets (27) of the accumulators (24a-24c) are performed by moving the screen carrier (14) to an accumulator drain position (SE), wherein in the accumulator drain position (SE), an accumulator connecting channel (32) fluidly connects the accumulators (24a-24c) to the periphery (40) of the filtering device (2) and the screen carrier inlet (68) is disconnected.

22. A filtration device for filtering fluids, particularly liquefied plastics, comprising: a housing having a receptacle for receiving the screen carrier and having a fluid inlet channel and a fluid outlet channel; 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; The screen carrier can be moved from a screen changing position (S) to a filtering position (F) via a degassing position area, 1. A filtration device, wherein an accumulator is fluidly connectable to the screen carrier inlet and / or the screen carrier outlet, the accumulator configured to store fluid channeled via the screen carrier inlet and / or the screen carrier outlet and to control the channeling of the fluid into the accumulator in a manner such that a volumetric flow rate (Q) of the melt, in particular the volumetric flow rate (Q) of the melt exiting the filtration device and channeled to a downstream system component, remains within a definable volumetric flow rate range (ΔQ).

23. 23. The filtering device according to claim 22, wherein the filtering device has a control unit configured to control the feeding of the fluid into the accumulator in such a way that a volumetric flow rate (Q) of the melt, in particular a volumetric flow rate (Q) of the melt leaving the filtering device and being sent to a downstream system component, remains within a definable volumetric flow rate range (ΔQ).

24. 24. The filtration device according to claim 23, wherein the volumetric flow rate (Q) of the melt is determined by a pressure sensor, preferably arranged within the filtration device, in particular within the fluid outlet channel.

25. 23. The filtering device of claim 22, wherein the accumulator is located in a separate housing or within the housing.

26. 23. The filtering apparatus of claim 22, wherein the housing includes an accumulator connection channel fluidly coupling the screen carrier inlet to an accumulator inlet depending on the position of the screen carrier relative to the housing.

27. 6. The filtering apparatus of claim 5, wherein the screen carrier is vented in the venting position area by directing fluid through the fluid outlet channel, and the accumulator connecting channel fluidly connects the screen carrier inlet to the accumulator inlet in the venting position area.

28. The screen carrier can be brought to a backflushing position area (R) where backflushing fluid is delivered to the filter element from the clean side of the filter element to the dirt side of the filter element, 27. The filtering device of claim 26, wherein the accumulator connection channel fluidly connects the screen carrier inlet and the inlet of the accumulator in the backflush location area (R).

29. 23. The filtration apparatus of claim 22, wherein the screen carrier has an outlet channel that fluidly connects the accumulator connecting channel to the surroundings of the filtration apparatus when the screen carrier is in an accumulator drain position (SE), such that fluid received in the accumulator can be discharged to the surroundings, and the accumulator connecting channel is disconnected from the screen carrier inlet in the accumulator drain position (SE).

30. 30. The filtering device of claim 29, wherein the accumulator drain position (SE) of the screen carrier coincides with the filtering position (F) of the screen carrier.

31. 23. The filtering device of claim 22, wherein the accumulator is embodied as a piston accumulator.

32. 32. The filtering device of claim 31 , wherein the piston accumulator has an accumulator chamber and a piston disposed within the accumulator chamber, the piston being actuable by an actuator, and the delivery of the fluid into the accumulator being controlled by the piston.

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

34. 33. The filtering device of claim 32, wherein the actuator is embodied as a rotary lift cylinder configured to rotationally drive the piston along the longitudinal axis of the accumulator and within the accumulator chamber, the piston having a longitudinal groove that interacts with the piston accumulator inlet or the piston accumulator outlet in a manner 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. 32. The filtering device of claim 31, wherein the piston accumulator has a valve with a piston accumulator outlet and a valve pin, the piston accumulator outlet being blocked or opened depending on the position of the valve pin relative to the piston accumulator outlet.

36. 33. The filtering device of claim 32, wherein the accumulator comprises a control valve coupled to the accumulator chamber and configured to apply pressure to or emptie the accumulator chamber.

37. the screen carrier is a first screen carrier, and the filtering device has at least a second screen carrier movably received within the housing and having a second screen carrier inlet; 23. The filtering apparatus of claim 22, wherein the housing includes a second accumulator connection channel fluidly coupling the second screen carrier inlet to the inlet of the accumulator depending at least on the position of the second screen carrier relative to the housing.

38. 23. A method for degassing a filtration device, in particular a filtration device according to claim 22, comprising the steps of: moving a screen carrier of the filtering device to a degassing position area; directing a degassing fluid through a fluid outlet channel of the filter device to displace air within the cavity of the screen carrier toward a screen carrier inlet; and routing the displaced air and / or the degassing fluid from the screen carrier inlet to an accumulator, wherein the routing of the fluid into the accumulator is controlled in such a way that a volumetric flow rate of the melt (Q), in particular the volumetric flow rate of the melt exiting the filtration device and being routed to a downstream system component (Q), remains within a definable volumetric flow rate range (ΔQ).

39. 23. A method for degassing a filtration device, in particular a filtration device according to claim 22, comprising the steps of: moving a screen carrier of the filtering device to a degassing position area; directing a degassing fluid through a fluid outlet channel of the filter device to displace air within the at least one cavity of the screen carrier toward a screen carrier inlet; and routing the displaced air and / or the degassing fluid from the screen carrier outlet to an accumulator, wherein the routing of the fluid into the accumulator is controlled in such a way that a volumetric flow rate of the melt (Q), in particular the volumetric flow rate of the melt exiting the filtration device and being routed to a downstream system component (Q), remains within a definable volumetric flow rate range (ΔQ).

40. 23. A method for backflushing a filtration device, in particular a filtration device according to claim 22, comprising: moving a screen carrier of the filtering device to a backflush position area; directing a backflushing fluid through a fluid outlet channel of the filter device such that the backflushing fluid is directed against the filter element from the clean side of the filter element to the dirt side of the filter element and the backflushed fluid is pushed towards the screen carrier inlet; and feeding the backflushed fluid from the screen carrier inlet to an accumulator, wherein the feeding of the fluid into the accumulator is controlled in such a way that a volumetric flow rate of the melt (Q), in particular a volumetric flow rate of the melt exiting the filtration device (2) and being fed to a downstream system component (Q), remains within a definable volumetric flow rate range (ΔQ).

41. closing the inlet of the accumulator; opening the outlet of the accumulator; Discharging the fluid contained in the accumulator from the accumulator via the outlet.

42. 42. The method of claim 41, wherein the steps of closing the inlet of the accumulator and opening the outlet of the accumulator are performed by moving the screen carrier to an accumulator drain position (SE), wherein in the accumulator drain position (SE), an accumulator connecting channel fluidly connects the accumulator to the periphery of the filtration device and the screen carrier inlet is disconnected.

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