SEGMENTS

Technical Field

The present invention relates to a filtering device for separating solid

5 particles and other objects from water.

Background of the Invention

Filtering devices are used, for example, for separating solid particles and other objects from municipal and industrial waste water. One type of

10 filtering devices uses a perforated conveyor belt which is formed of a large

number of mutually articulately connected perforated segments. The conveyor belt is led in an elongated closed path through a soiled water flow, whereby the particles and the objects which cannot pass through the perforations are captured and can be transported away from the water flow.

15 The hereby captured waste can be separated off from the conveyor belt by,

for example, a brush, a water flow, compressed air or a scraper.

Conveyor belts for this type of applications are usually produced from a large number of mutually articulately connected segments. The segments can, for example, be mutually connected by means of hinges which extend

20 transversely to the motional direction of the conveyor belt. Other solutions comprise segments which, along a first long side, are fastened articulately about an axis extending transversely to the motional direction of the conveyor belt and in which the opposite, second long side is arranged to overlap the first long side, articulately fastened in a corresponding manner, of another,

25 adjoining segment. A typical example of such a solution is given, for example, by US2006/0070858. The overlap forms something which can be likened to a labyrinth seal, which prevents particles and objects from penetrating into and getting stuck in the gap between two consecutive segments. There are also examples in which the conveyor belt is provided with loose sealing strips which extend into or over the gap between two consecutive segments. This is described, for example, in US 7 510 650.

In the design of a conveyor belt, it is important to avoid unnecessary gaps. This applies both between the individual segments and between the conveyor belt and the side walls which enclose the conveyor belt along the longitudinal side walls of the frame. As a result of the relatively high velocity of the flowing water, correspondingly large particles and objects can pass more or less unhindered through these gaps and can run along with the filtered water. The water is hence not sufficiently purified, which can call for further purification and/or problems in the following treatment of the water.

Alternatively, over-large particles and objects get stuck in the gaps, which can damage both the conveyor belt and its drive mechanism. In the long run, this can lead to total breakdown of the filtering device. Summary of the Invention

The object of the present invention is to provide a filtering device for separating solid particles and other objects from water, comprising a conveyor belt which has no gaps between adjoining segments. By gaps is meant in this regard continuous, substantially rectilinear openings between two consecutive segments.

Another object is that the conveyor belt shall be simple to produce and assemble to the desired length.

A further object is that the conveyor belt shall be able to be fitted in existing filtering devices subject to minor modifications.

These and yet more objects are met by a filtering device for separating solid particles and other objects from water.

The filtering device comprises a conveyor belt arranged to run in a closed path through a water flow, which conveyor belt comprises mutually articulately connected perforated segments, each segment having a first long side and a second long side opposite to said first long side, which long sides have a longitudinal extent transversely to the motional direction of the path, and two mutually opposite short sides having a longitudinal extent along the motional direction of the path, the first long side of each segment comprising a hook section which is articulately hooked in a hook section of the second long side of a following segment to form said closed path.

The filtering device can be used for various applications in which there is a demand for the separation of particles and other objects. This can concern, for example, the filtration of so-called raw water in connection with raw water intake for waterworks and cooling water plants. It can also concern, for example, the filtration of municipal or industrial waste water. The conveyor belt is assembled to the desired length by the connection of a desired number of perforated segments, which are hooked together side by side by means of mutually interacting hook sections. As a result of the hook fastening, the conveyor belt acquires a surface which has no substantially linearly

continuous gaps through which particles and other objects which are meant to be separated off can unintentionally be led or get stuck. This reduces the need for maintenance. In addition, further subsequent purification of the filtered water, should the process owner call for this, is facilitated.

The individual segments can be produced at an extremely low cost and in turn allow an extremely simple assembly for the formation of the closed path of the conveyor belt. No further fastening elements such as hinges, shafts or screws are required, which in turn also impacts on the total cost.

The hook fastening gives something which can be likened to a labyrinth seal, in which the waste which is captured by the perforated segments during the continuous feed of the belt in the closed path is prevented from "wandering" in through the hook joint and making its way out on the rear side of the segments and being met there by filtered water.

In addition, the commonly used cleaning of the conveyor belt, in which the particles and the waste which is captured by the perforations of the segments is constantly removed by means of, for example, rotating brushes, rakes, water or compressed air, is facilitated. This cleaning often takes place in connection with a change of direction of the conveyor belt over a deflection roller. With a belt design according to the invention, should the filtering device be used in a water flow which is primarily directed toward the outside of the conveyor belt, upon such a change of direction a natural opening of the joint will occur, since two consecutive segments, during this change of direction, are mutually slanted and partially open up the hook joint and thereby provide access for bristles/wash water/compressed air in the space between the long sides of the two segments. Despite the hook joint having been partially, there remains the previously discussed gapless labyrinth seal, which prevents the dirt from possibly wandering down to the bottom side of the conveyor belt. Where the filtering device is used in a water flow which is primarily directed toward the inside of the conveyor belt, something which can be likened to self-cleaning instead occurs, due to mutual inevitable movement between the segments.

Each segment, viewed in a cross section transversely to the

longitudinal direction of the belt, can have a substantially S-shaped cross section comprising a web extending between a first and a second hook section. The substantially S-shaped cross section can be obtained in a simple manner by bending. It will be appreciated that the web per se can be given different cross sections. The web advantageously has a curvature, bending or stepped shape transversely to the motional direction of the path so as to lend the segments sufficient stiffness to withstand the pressure from flowing water. The segments can also be provided with one or more stiffenings.

The first and the second hook section can comprise a flange, which, viewed in a region adjacent to the long side of the segment, forms an angle of less than 60 degrees relative to the web. The angle advantageously has a magnitude within the range 25-50 degrees.

Each segment can comprise along its short sides two opposite side wall elements having a longitudinal extent along the motional direction of the path, in which the side wall elements of two consecutive segments together form two opposite side walls having an extent along the motional direction of the belt, wherein each segment is arranged to extend between two

consecutive side wall elements, and wherein each segment is fixedly connected to a first of two consecutive side wall elements.

The fact that each segment is arranged to extend between and be in contact with two consecutive side wall elements means that a substantially gapless and continuous side wall is formed on opposite sides of the conveyor belt. The segments, together with the side wall elements, give the conveyor belt a trough-shaped cross section having a depth corresponding to the height of the side wall elements. In addition, the fixed connection contributes to the stiffness of the segments, so that these can withstand the pressure from flowing water. The fixed connection also reduces a gap formation between the short sides of the segments and the side wall elements.

The respective side wall element can comprise a bracket, facing toward the web of the segment, for fixed connection of the web of the segment against the side wall element. The webs of the segments can be connected against the brackets by, for example, screwing, welding or riveting. A form of labyrinth seal is hereby formed between segment and side wall element along the motional direction of the belt.

The conveyor belt can be arranged to be propelled by a drive chain which interacts with the side wall elements, which drive chain comprises running rollers, and link arms extending between the running rollers, to form a closed drive chain, wherein each side wall element comprises a recess for receiving a center shaft of the respective running roller, wherein the center shaft, in the assembly of the drive chain, is guidable in said recess between an insertion position, in which the center shaft is allowed to be guided in a direction perpendicular to the plane of extension of the side wall element, and a drive position, in which the center shaft is allowed to be freely rotated relative to the recess, yet at the same time has a limited guidability in the direction perpendicular to the plane of extension of the side wall element.

The recess and its interaction with the center shaft of the running roller can be likened to a bayonet coupling, thereby giving a simple assembly and, not least, disassembly of the drive chain relative to the conveyor belt.

The recess for receiving a center shaft can have the shape of a long hole comprising a first section having a first diameter and a second section having a second diameter, wherein the center shaft in its drive position is substantially centered relative to said second section. By virtue of this type of long hole, the side wall elements are forced into a centering relative to the drive chain, whereby wear is reduced.

The center shaft can be arranged to be detained in said drive position by link arms adjacent to the running roller being articulately connected to side wall elements lying opposite to the respective link arm. The articulated connection is most easily allowed by a pivot pin which extends between the side wall element and that link arm which is arranged closest to the side wall element.

According to another aspect, the invention relates to the use of a filtering device according to the above-given description for separating particles and other objects from water.

Brief Description of the Drawings

The invention will now be described in greater detail with reference to accompanying drawings.

Figs 1 a and 1 b show perspective views, viewed from the front and rear respectively, of one example of a filtering device intended for filtering of water by means of a flow of water out from and in toward the conveyor belt.

Fig. 2 shows a second example of a filtering device in which the waste water is led through the conveyor belt from the inside, and out.

Fig. 3 shows a part of a conveyor belt with side walls and drive chain.

Fig. 4 shows a cross section of two segments hooked articulately together.

Fig. 5 shows a partial enlargement of the hook sections of two segments hooked articulately together.

Fig. 6 shows the rear side of a part of a conveyor belt.

Fig. 7 shows an example of the interaction between the drive chain and the frame.

Description of a Preferred Embodiment

With reference to figs 1 a and 1 b, an example of a filtering device 1 which is intended for filtering a flow of water is shown. The filtering device 1 comprises a frame 3 in which a perforated conveyor belt 2 is led in a closed path over two mutually spaced deflection rollers 1 1 . Only the lower deflection roller 1 1 is shown. For easier clarity, the conveyor belt 2 is shown without perforations. The upper part of the filtering device 1 comprises a first motor 4, which is intended to propel the conveyor belt by driving of the upper deflection roller (not shown).

The filtering device 1 further comprises in its upper part a second motor 5 for driving a belt cleaning device (not shown). The belt cleaning device can be constituted, for example, by a rotating brush, which bears against the conveyor belt. It will be appreciated that other cleaning methods, too, are possible, such as rakes, water flow or compressed air.

The frame 3 comprises two opposite side walls 6, which extend along the conveyor belt 2. In the shown embodiment, the respective side wall 6 has two openings 7. It will be appreciated that the number of openings 7 and their geometry can vary. The frame 3 further comprises in its upper front wall section cover plates 8, which extend between the two side walls 6. The cover plates 8 are arranged as inspection hatches for allowing access to the conveyor belt 2 along substantially the whole of its length.

With particular reference to fig. 1 b, the frame 3 in its shown

embodiment comprises on its rear side two stays 9, which extend between the side walls 6 for stiffening of the frame 3. In the shown embodiment, the rear side of the frame 3 is thus substantially open. It will be appreciated that the rear side can be covered with one or more cover plates.

The frame 3 further has in its upper rear section a hood 9 having a lower opening 10. The hood 9 with its opening 10 forms a passage for evacuation of the particles and the waste which have been captured by the conveyor belt 2 and which are separated off by means of the belt cleaning device (not shown).

The filtering device is intended during use to be immersed with its lower end in a flow of dirty water in such a way that the conveyor belt 2 extends substantially transversely to the flow of dirty water. The flow is illustrated with arrows in fig. 1 a.

When the dirty water hits the conveyor belt 2, particles and other waste with a size exceeding the perforations will be prevented from passing through the conveyor belt 2, at the same time as the filtered water is allowed to pass through the perforations and is led out primarily via the rear side of the frame 3. An evacuation also takes place in the lateral direction and away from the filtering device 1 through the openings 7 in the side walls 6 of the frame 3.

Through the feed of the conveyor belt 2 in a closed path, the hereby separated particles and the waste will be led up and away from the water flow. In order to avoid a situation in which the particles and the waste are returned on the return circuit of the conveyor belt, the particles and the waste are separated off from the conveyor belt 2 by means of the belt cleaning device (not shown). The separated waste can be captured in a vessel (not shown) for further destruction.

Now with reference to fig. 2, another principle for a filtering device 1 is shown. The overriding principle is the same as has been described above, but with the difference that the water, see arrows, which is to be filtered is led in toward the inside of the closed path formed by the perforated conveyor belt 2. For easier illustration, the conveyor belt is shown without perforations. The water flow is forced to change direction by a rear side wall section 12 of the frame 3 and is pressed through the conveyor belt 2 and further out through openings 13 in the opposite side walls 14 of the frame 3. The particles and the waste which are separated off are hereby captured on the inside of the conveyor belt 2. In this type of filtering device, the separated waste is removed by virtue of the fact that the waste falls off from the conveyor belt 2 as a result of the mutual movement of the segments 15 and can be collected on the bottom of the filtering device 1 . The principle is otherwise the same as above and is thus not described further.

Now with reference to fig. 3, a part of a conveyor belt 2 according to the invention is shown. The conveyor belt 2 is applicable in, for example, both types of filtering devices which have been described above. For easier understanding, fig. 3 shows two segments 15 which have been lifted up from the conveyor belt 2. The conveyor belt 2 per se is made up of a number of mutually articulately connected segments 15 forming a bottom surface 16. In order to facilitate illustration, the perforations of the segments 15 have been omitted.

The conveyor belt 2 is delimited in the lateral direction by two opposite, substantially continuous side walls 17, which are formed by a number of mutually interacting side wall elements 18. The side walls 17, together with the segments 15, give the conveyor belt 2 a substantially trough-shaped cross section viewed in a direction along the motional direction of the path

(arrow A). The side wall elements 18 are in turn connected to a drive chain 19. The drive chain 19 comprises link arms 20, which extend between running rollers 21 . A drive chain is advantageously arranged on opposite sides of the conveyor belt 2.

With reference to figs 4 and 5, a cross section of two mutually articulately connected segments 15 is shown schematically. Fig. 5 shows a partial enlargement of the connection between the segments 15. In the shown cross sections, the length of the long sides of the segments is heavily reduced in relation to the length of the short sides.

Each segment 15 has a first long side 22a and a second long side 22b lying opposite said first long side 22a. The long sides 22a, 22b have a longitudinal extent, see arrow B, transversely to the motional direction of the path, see arrow A. Each segment 15 further has two mutually opposite short sides 23 having a longitudinal extent along the motional direction of the path, see arrow A.

Each segment 15, viewed in a cross section transversely to the motional direction of the belt, see arrow A, has a substantially S-shaped cross section comprising a web 25 extending between a first and a second hook section 24. The web is provided with perforations P.

The web 25 which forms the actual bottom surface 16 of the conveyor belt 2 has in the shown embodiment a bent cross-sectional profile forming two folds 26, which extend transversely to the motional direction of the belt, see arrow A. The folds 26 help to lend stiffness to the segments 15 in order to withstand the water flow. The folds 26 further help to detain collected waste prior to separation. It will be appreciated that the cross-sectional profile of the web 25 can be varied and that the invention shall not be limited to the shown embodiment. It will also be appreciated that the segments 15 can be provided with stiffening rails which extend along and/or transversely to the segments, viewed in the motional direction of the path. The hook sections 24 are arranged to extend along the opposite long sides 22a, 22b of the segments 15. In the shown embodiment, the hook sections 24 are configured by the long sides 22a, 22b having been bent to form flanges 27, which, viewed in a region adjacent to the long side 22a, 22b of the segment, form an angle a of less than 60 degrees relative to the web 25. The angle a is preferably 25-50 degrees.

The hook section 24 on the first long side 22a of each segment 15 is articulately hooked in the hook section 24 of the second long side 22b of a following segment 15 to form said closed path.

Now with new reference to fig. 3, each segment 15, along its opposite short sides 23, is connected to two opposite side wall elements 18. The side wall elements 18 have a longitudinal extent along the motional direction of the path, arrow A.

The side wall elements 18, viewed along the motional direction of the path, arrow A, have a first and a second short side 28a, 28b. The short sides 28a, 28b have mutually complementary profiles, which in the shown embodiment are formed by a convex, single-curved first short side 28a and a thereto complementary concave, single-curved second short side 28b. The short sides 28a, 28b of two consecutive side wall elements 18 can hereby slide toward each other and form a substantially gapless mutual contact even when the conveyor belt 2 makes a change of direction over a deflection roller. In addition, the side wall elements 18 together form a continuous,

substantially gapless side wall 17, which extends along and on opposite sides of the closed path of the conveyor belt 2.

The respective side wall element 18 comprises a bracket 29 facing toward the web 25 of the segment 15. The bracket 29 has a profile

corresponding to a part of the cross section of the web 25 of the segment 15. The bracket 29 is expediently formed by a bent profile which is welded or otherwise connected to the side wall element 18.

Each segment 15 is fixedly connected to a first of two consecutive side wall elements 18. In the shown embodiment, the segments 15 are screwed to the brackets 29. Other fastening methods, too, can be used, for example welding or riveting. In the shown embodiment, each segment 15 is arranged to extend between two consecutive side wall elements 18. This is realized by virtue of the fact that the first long side 22a of a first segment 15a is displaced relative to the convex short side 28a of the corresponding first side wall element 18a, at the same time as its opposite, second long side 22b is displaced relative to the opposite, concave short side 28b of the side wall element and thus projects beyond this short side.

With reference to figs 3 and 6, the conveyor belt 2 is arranged to be propelled by a drive chain 19 which interacts with the side wall elements 18. The drive chain 19 comprises running rollers 21 , and link arms 20 extending between the running rollers 21 , to form a closed drive chain 19. In the shown embodiment, two mutually parallel link arms 20 extend between two

consecutive running rollers 21 . The link arms 20 are rotatably connected to the center shafts 30 of the running rollers 21 and articulately connected to the side wall elements 18 via pivot pins 31 .

The drive chain 19 interacts with the side wall elements 18 by virtue of the fact that each side wall element 18 comprises a recess 32 for receiving a center shaft 30 of a running roller 21 . The recess 32 has the shape of a long hole comprising a first 33 section having a first diameter and a second section 34 having a second diameter. It will be appreciated that at least the first section 33 can have a geometry other than substantially circular.

The center shaft 30 preferably has an end profile (not shown) having a cross section which has a geometry which is less than the diameter of the first section 33 of the recess 32, but which at the same time is greater than the diameter of the second section 34 of the recess 32. The essential point is that the center shaft 30 has an end profile which can freely be guided in and out through the first section 33, but which is prevented from being guided in or out through the second section 34 in a direction perpendicular to the plane of extension of the side wall element 18.

In the assembly of the drive chain 19 relative to the side wall elements

18, that end of the center shaft 30 of the running roller 21 which is facing toward the side wall element 18 is guided into the first section 33 of the recess 32 in a direction perpendicular to the plane of extension of the side wall element 18. This constitutes an insertion position. In its inserted position, the center shaft 30 is guided in the direction of the second section 34 of the recess 32 and is centered relative thereto. In this centered position, which constitutes a drive position, the center shaft 30 is freely rotatable relative to the recess 32, yet at the same time is limitedly guidable in a direction perpendicular to the plane of extension of the side wall element 18. The centering of the center shaft 30 relative to the second section 34 can be realized, for example, by the diameter of the center shaft 30 substantially corresponding to the diameter of the second section 34.

The center shaft 30 is subsequently fixed in the drive position by virtue of the fact that the link arms 20 which adjoin the running roller 21 on both sides thereof are arranged articulately against the opposite side wall element 18. This is realized in the shown embodiment by the fitting of a pivot pin 31 through a previously made hole 35 in the side wall element 18 and the link arm 20. This is allowed by virtue of the fact that the center distance between the center shaft 30 and the hole 35 arranged in the link arm 20 corresponds to the center distance between the second section 34 of the recess 32 and the hole 35 previously arranged in the side wall element 18.

According to the above, the first long side 22a of a first segment 15a is displaced relative to the convex short side 28a of the corresponding first side wall element18a, at the same time as its opposite, second long side 22b is displaced relative to the opposite, concave short side 28b of the side wall element and thus projects beyond this short side. The displacement shall be such that the center of rotation between two hooked together hook sections 24 shall coincide with the center shaft 30 of the adjacent running roller 21 .

Now with reference to fig. 7, a cross section of the conveyor belt 2 adjacent to one side wall 6 of the frame 3 is shown. The running rollers 21 of the drive chain 19 are arranged to run between two stationary roller rails 36. The roller rails 36 are preferably arranged to extend along the side walls 6 of the frame 3 and lend support to the running rollers 21 when the drive chain 19 is driven by the motor (see fig. 1 a) which is intended to drive the conveyor belt 2. In order to protect the drive chain 19 from penetration of unfiltered water, it is advantageous to arrange a sealing strip 37 along that side wall 17 of the conveyor belt 2 which during use is intended to be facing toward a flow of unfiltered water. Depending on the configuration of the filtering device and the intended direction of flow of the water, the sealing strip 37 can be arranged along the top side or bottom side of the conveyor belt 2. In the illustrated example, the sealing strip 37 is arranged to grip around the lower edge of the side wall element 18 on both sides of this edge. It will be appreciated that the sealing strip 37 can be configured in a host of different ways and that the invention shall not be limited to the configuration of the sealing strip.

The description above should be regarded as one example of a possible configuration of segments, side wall elements and drive chain. It will be appreciated that the cross section of the segments and the profile of the side wall elements can be configured in a host of different ways within the scope of the invention.

It will further be appreciated that the segments with maintained function can be given a host of different perforation patterns.