FILTERING DEVICE FOR HIGHLY VISCOUS MEDIA

Abstract

A filtering device for highly viscous media, in which filtering device a rotatably mounted screening wheel which has a plurality of screening cavities is arranged between a front housing element and a rear housing element. According to the invention, a plurality of screening cavities lying beside one another, through which flow can pass jointly, are combined into at least one filter group. To this end, on both sides beside the filter group, a closed blocking segment is provided on the screening wheel which segment, when positioned in associated blocking regions of the housing, is sealed off with respect to the housing elements on both sides of the screening wheel. The blocking regions in the housing are in each case larger than or as large as a screening cavity together with a sealing web surrounding the same.

Claims

1. A filtering device for highly viscous media, the filtering device comprising: a housing that has a front housing element with at least one inflow channel and has a rear housing element with at least one outflow channel; a screen wheel mounted rotatably between the housing elements and has a number n of screen cavitie, which are each to be provided with at least one screen insert element and, for sealing with respect to the housing elements, are each surrounded by at least one sealing web; a filtering region covered by the housing and has a flow connection with the inflow channel and the outflow channel and in which at least one screen cavity is adapted to be flowed through; a maintenance region in which at least one screen cavity is exposed outside the housing (10; 10′) and/or is accessible from a housing outer side; and two blocking regions in the housing that are each formed between the filtering region and the maintenance region and in which in each case at least one screen cavity (together with sealing web is adapted to be covered completely by the front and rear housing elements and has no flow connection with the inflow channel and the outflow channel, wherein, on the screen wheel, multiple screen cavities situated one next to the other are combined to form at least one filter group, which, in the case of at least partial overlapping with the filtering region of the housing, are adapted to be flowed through in a joint manner, wherein an area on the screen wheel which is covered by the filtering region of the housing is larger than a screen cavity, wherein, on both sides, next to the filter group, there is provided on the screen wheel at least one closed blocking segment, which, when positioned in the blocking regions of the housing, is sealed off with respect to the housing elements on both sides of the screen wheel, and wherein the blocking regions in the housing are in each case larger than or equal in size to a screen cavity together with sealing web.

2. The filtering device as claimed in claim 1, wherein the housing elements, in the filtering region have on their surfaces facing toward the screen wheel in each case one planar depression or at least one overflow channel.

3. The filtering device as claimed in claim 1, wherein the blocking segments take up a smaller area on on the screen wheel than the filter groups.

4. The filtering device as claimed in claim 1, wherein, in the maintenance region, there is provided a housing opening which is larger than or equal in size to a screen cavity.

5. The filtering device as claimed in claim 1, wherein the screen insert elements in the screen cavities and the associated recesses in the side surfaces of the screen wheel are circular segment-like.

6. The filtering device as claimed in claim 5, wherein the screen wheel is subdivided into circular ring segment surfaces of differing size, wherein the circular ring segment surface(s) serving as blocking segment(s) is (are) larger than the segments in the filter groups which have segment cavities.

7. The filtering device as claimed in claim 1, wherein the screen insert elements in the screen cavities and the associated recesses in the side surfaces of the screen wheel are round.

8. The filtering device as claimed in claim 1, wherein the screen wheel is subdivided into n circular ring segment surface, where n≥6, and wherein three circular ring segment surfaces situated one next to the other form a common blocking segment, and (n−3) circular ring segment surfaces form a filter group.

9. The filtering device as claimed in claim 8, wherein a housing opening which has the size of a circular ring segment surface) is provided in the maintenance region.

10. The filtering device as claimed in claim 8, wherein the number of circular ring segment surfaces is n=8 to 12.

11. The filtering device as claimed in claim 1, wherein the screen wheel is subdivided into n circular ring segment surfaces, where n≥6, wherein, on diametrically opposite sides of the screen wheel, there is formed one filter group which comprises at least two screen cavities situated one next to the other, wherein between the filter groups, at least one circular ring segment surface is formed as a blocking segment; and wherein a housing opening which is in each case larger than or equal in size to a filter group is provided in the maintenance region.

12. The filtering device as claimed in claim 11, wherein, in a working position for the filtering operation, all the screen cavities, which are configured to be occupied by screen insert elements, are arranged either in a filter group situated in the filtering region or in a filter group situated in the maintenance region.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus, are not limitive of the present invention, and wherein:

[0027] FIG. 1 shows a perspective view of a filtering device according to a first embodiment;

[0028] FIG. 2 shows, in plan view, a screen wheel for the filtering device according to an exemplary embodiment;

[0029] FIG. 3 shows a front view of the filtering device with a first position of the screen wheel;

[0030] FIG. 4 shows a front view of the filtering device with a second position of the screen wheel;

[0031] FIG. 5 shows a perspective view of a filtering device according to an exemplary embodiment;

[0032] FIG. 6 shows, in plan view, a screen wheel for the filtering device according to the exemplary embodiment;

[0033] FIG. 7 shows a front view of the filtering device according to FIG. 5 with a first position of the screen wheel; and

[0034] FIG. 8 shows a front view of the filtering device according to FIG. 5 with a second position of the screen wheel.

DETAILED DESCRIPTION

[0035] FIG. 1 shows a filtering device 100 according to an exemplary embodiment of the invention in a perspective view. The basic construction corresponds to the known type of a screen wheel changer filtering device and includes a housing 10, which has a plate-like front housing element 11 through which an inflow channel 15 passes and has a likewise plate-like, rear housing element 12 through which an outflow channel passes.

[0036] A screen wheel 20, which is arranged in a gap 13 between the housing elements 11, 12, which are arranged in a plane-parallel manner, and is rotatable about an axis of rotation 14.

[0037] What characterizes the invention is, in the case of the filtering device 100 according to FIG. 1, firstly a maintenance opening 16 in the housing 10 that is trapezoidal in a side view. Furthermore, the screen wheel 20 of the filtering device 100 differs from the prior art in that that part of the screen wheel 20 which is visible in the maintenance position 16 during the filtering operation is designed as a so-called blocking element 23, that is to say there are no screen cavities there.

[0038] The screen wheel 20 is shown in plan view in FIG. 2. The basic configuration provides for the division of a circular ring zone around a central hub 25 into a number n of equal circular ring segments. In the exemplary embodiment illustrated in FIG. 2, n=10 was selected, with the result that each segment includes an angle of 36°. Three segments 23.1, 23.2, 23.2 together form the blocking segment 23. In all the other circular ring segments, there is formed in each case one screen cavity 21.1, . . . , 21.7 having in each case one screen opening which extends through the entire width of the screen wheel 20 and which can be covered by a screen element. All the screen cavities 21.1, . . . , 21.7 together form a filter group 2 which can be flowed through as a whole unit, although each screen cavity 21.1, . . . , 21.7 is delimited at its periphery via a sealing web. For each individual screen cavity, the sealing web is made up of: an inner arcuate portion which extends around the hub 25; an outer arcuate portion at the outer boundary of the screen wheel 20; and at least one radial sealing web 22.1, . . . , 22.6.

[0039] Adjacent screen cavities 21.1, . . . , 21.7 have a common radial sealing web between them. The boundary-side screen cavities 21.1, 21.7 are each delimited to one side by radial edges of the blocking segment 23, which radial edges, in a functional sense, are likewise considered to be a sealing web in the context of the invention.

[0040] FIG. 3 shows a plan view of the front housing element 11 of the housing 10, with the screen wheel 20, which is situated therebehind in a concealed manner, being additionally illustrated. In FIG. 3, the screen wheel 20 is in the production position for the filtering operation. The filter group 2 of the screen wheel 20 is in congruence with the filtering region 17 in the housing 10. What is involved here is a recess in the respective contact surface, facing toward the screen wheel 20, of the housing elements, which recess has a flow connection with the inflow channel 15 or, in the case of the rear housing element, with the outflow channel. Due to the depression in the filtering region 17, the radial sealing web portions 22.1, . . . , 22.6 between the screen cavities 21.1, . . . , 21.7 are flowed over, with the result that all the screen cavities 21.1, . . . , 21.7 of the filter group 2 are flowed against together from a single inflow channel 15. The outflow side is formed analogously, so as to re-combine the liquid, such as in particular molten plastic, which has been filtered at different screen cavities 21.1, . . . , 21.7, and to guide said liquid out of the housing 10 via an outflow channel.

[0041] Blocking regions 18,1, 18,2 are formed on the housing 10 on both sides of the maintenance opening 16. In said blocking regions, that surface of the housing elements which faces toward the screen wheel 20 is smooth and abuts almost directly against the sealing webs. Consequently, lateral outflow of the medium via the screen wheel 20 is ruled out. Although the blocking regions 18.1, 18.2 could, purely in order to achieve the blocking action, also be significantly narrower, they are kept in the described division of the screen wheel 20 into n=10 uniform circular ring segments.

[0042] The advantage of this division will become clear in the next illustration. In FIG. 4, the filtering device 100 is illustrated in a transition phase. In comparison with the position according to FIG. 3, the screen wheel 20 has been rotated through two angular increments, each of 36°, in the counterclockwise direction. Consequently, parts of the blocking segment 23 of the screen wheel 20 are now situated within the filtering region 17. The screen cavities 21.3, . . . , 21.7 remain therein as usable filter surfaces. The filtering operation can thus be continued via the five remaining screen cavities 21.3, . . . , 21.7.

[0043] Due to the rotation, the screen cavity 21.1 is placed in the region of the maintenance opening 16, so that, there, the screen element can be exchanged or cleaned. The trapezoidal shape of the maintenance opening 16 is necessary for saving as much space as possible and for having available, as blocking region 18.1, 18.2, the entire adjacent surface in the housing 10 according to a circular ring segment. The surface in the blocking region 18.1, 18.2 is thus at least as large as the extent of the sealing webs which surround the screen cavity 21.2, with the result that the screen cavities, together with sealing webs, are covered over the full area on both sides of the screen wheel plate. Due to the covering, precisely the one screen cavity 21.2 is sealed off. Although the screen cavity 21.2 is, in a structural sense, part of the commonly usable filter group 2, in this position, it is completely blocked and functionally separate from the filter group 2.

[0044] For further maintenance, the screen wheel 20 is always further rotated through an angular increment, with the result that the screen cavities 21.3, . . . , 21.7 appear at the maintenance opening 16 in steps. During this time, the blocking segment 23 is moved completely through the filtering region 17 one time.

[0045] FIG. 5 shows a filtering device 100′ according to a second embodiment of the invention in a perspective view. The basic construction is also as in the first embodiment and comprises: a housing 10′, which has a plate-like front housing element 11′ through which an inflow channel 15′ passes and has a likewise plate-like, rear housing element 12′ through which an outflow channel passes; and a screen wheel 20′, which is arranged in a gap 13′ between the housing elements 11′, 12′, which are arranged in a plane-parallel manner, and is rotatable about an axis of rotation 14′.

[0046] What characterizes the invention is, in the case of the filtering device 100′ according to FIG. 5, the maintenance opening 16′ on the left-hand side of the housing 10′ that is diabolo-like in a side view. That part of the screen wheel 20′ which is visible in the maintenance position 16′ during the filtering operation contains a complete filter group 2, which comprises four individual and separately blockable but also jointly usable screen cavities 21.1′, . . . , 21.4′ which, in the maintenance position 16′, are all simultaneously openly accessible.

[0047] The screen wheel 20′ is shown in plan view in FIG. 6. Again, the basic configuration provides for the division of a circular ring zone around a central hub 25′ into n circular ring segments of equal size. In the illustrated exemplary embodiment, n=10 was selected, with the result that each segment includes an angle of 36°.

[0048] Two segments at diametrically opposite positions at 12 o'clock and 6 o'clock each form a blocking segment 23.1′, 23.2′. The blocking segments 23.1′, 23.2′ divide the screen wheel 20′ into two filter groups 2′, 4′ with in each case four screen cavities 21.1′, . . . , 21.4′, 21.5′, . . . , 21.8′. These have in each case one screen opening which extends through the entire width of the screen wheel 20′ and which can be covered by an insertable filter element or screen element.

[0049] The screen cavities 21.1′, . . . , 21.4′ and 21.5′, . . . , 21.8′ situated one next to the other in each case form a filter group 2′ and 4′, respectively, which can be flowed through as a whole unit, although each screen cavity 21.1′, . . . , 21.8′ is individually delimited at its periphery. The delimitation is made up of an inner arcuate portion, an outer arcuate portion and two radial sealing webs 22.1′, . . . , 22.6. Adjacent screen cavities 21.1′, . . . , 21.4′ and 21.5′, . . . , 21.8′ have a common radial sealing web between them. Boundary-side screen cavities 21.1′, 21.4′ and 21.5′, 21.8′ are moreover outwardly delimited by radial edges of the in each case adjacent blocking segment 23.1′, 23.2′.

[0050] FIG. 7 illustrates the screen wheel 20′ within the housing 10′ in a side view, specifically during the filtering operation of the filtering device 100′. The left-hand filter group 2′, with the four screen cavities 21.1′, . . . , 21.4′, is fully exposed in the maintenance position 16′. Blocking regions 18.1′, 18.2′ are formed on the housing outer boundary, in each case above and below the axis of rotation 14′. The blocking segments 23.1′, 23.2′ of the screen wheel 20′ are in a state of sealing abutment in said blocking regions. Consequently, in turn, the other filter group 4′, which, with its screen cavities 21.5′, . . . , 21.8′, is situated completely within the filtering region 17′ in the housing 10′, is laterally sealed off. The screen cavities 21.5′, . . . , 21.8′ of the filter group 4′ are flowed through together, proceeding from the inflow channel 15′.

[0051] For the position of the screen wheel 20′ shown in FIG. 8, rotation through three segment increments has been realized in comparison with FIG. 7. Although, in this intermediate position too, maintenance for the screen cavities 21.1′, 21.2′, 21.8′ positioned within the maintenance opening 16′ could also already be performed, it is preferable for the screen wheel 20′ always to be rotated through in each case 180°, so that the position of the filter groups 2′, 4′ is swapped and it is always the case that all the screen cavities are positioned either in the filtering region 17′ or in the maintenance opening 16′. The position of the screen wheel 20′ according to FIG. 8 therefore constitutes merely a through-passage position. What is essential for the invention, however, is that, in this and other intermediate positions, a flow through multiple screen cavities remains possible at all times in the filtering region 17′. At most one of the two blocking segments 23.1, 23.2 can pass into the filtering region, and so, in all the screen wheel positions, there remain 3 of 4 screen cavities which can be flowed through and thus there is always—based on the segmentation selected here for the exemplary embodiment—at least 75% of the surface in the filtering region 17′ available.

[0052] The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are to be included within the scope of the following claims.