Abstract:
A method for removing a filter cake from a filtering device having a housing that defines a filtration flowpath through which a filtrate flows, the housing having at least one inlet and at least one outlet, the filter cake being deposited on at least one cylindrical filter element disposed within the filtering device, the at least one cylindrical filter element comprises at least one filter material and at least one rebound element, the at least one rebound element having a first flange extending from a head region and a second flange extending from a foot region, the at least one rebound element having a structured surface with at least two recesses mutually parallel in the longitudinal direction of the at least one rebound element, the at least two recesses are formed extending between the first flange and the second flange.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional application of U.S. patent application Ser. No. 12/430,531, filed on Apr. 27, 2009, which is a continuation of PCT/EP2007/009123 filed on Oct. 22, 2007, which claims priority to German Patent Application DE 10 2006 050 127.6 filed on Oct. 25, 2006, all of which are incorporated herein by reference in the entirety. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to a filtering device for cleaning particularly a liquid and/or gaseous medium as well as to a filter element that can be inserted in this filtering device and also to a method for cleaning a medium and to a method for removing a filter cake that has become deposited in the filtering device according to the invention. 
     BACKGROUND OF THE INVENTION 
     Many different filtering devices for cleaning liquid and/or gaseous media or corresponding mixtures, including also high-viscosity and oily media, are known from the state of the art. A particularly problematic aspect of the filtering devices that are known from the state of the art is the removal of the filter cake that becomes deposited on a filter element contained in the device, or mud collected there. On this subject, U.S. Pat. No. 7,055,699 B2 proposes a self cleaning mechanical filter, where a cleaning device is integrated in the filtering device disclosed there and presents suction and washing nozzles that are arranged opposite each other, and where the suction nozzles rest directly against the filter element, and the suction nozzles and the washing nozzles are moved synchronously in the axial and radial direction for removal of the filter cake. The cleaning of the filtering device that is disclosed in U.S. Pat. No. 7,055,699 B2 is very complicated and requires complex control. In addition, because of the movement in both the axial and also the radial direction, a relatively high mechanical driving force needs to be applied, which makes the filtering device disclosed there relatively costly. 
     Moreover, a filtering device according to the preamble is disclosed in WO 2006/008729, where, for the removal of a filter cake on a filter element in a filtering device, a cleaning head with a nozzle is defined particularly, which rests directly against the filter element, and through which, due to a pressure difference that builds up during the cleaning, the filter cake is sucked off the filter element. For the filtering device that is disclosed there to work properly, it is, however, always necessary to guide the cleaning head of the cleaning device so that it rests directly against the filter element, with the result that the pressure difference that can be generated for cleaning is insufficient in the case of slight unevenness that develops particularly in the filter elements or their surfaces in the case of prolonged use of the filtering device. 
     The problem of the present invention therefore is to make available a filtering device whose filter material or whose filter element(s) can be cleaned particularly well and simply due to the construction of the device, and which in addition effectively cleans a medium to be cleaned, regardless of whether the latter is gaseous, liquid or a mixture that may be of any type. 
     SUMMARY OF THE INVENTION 
     This problem is solved by a filtering device with a housing with at least one filter element arranged in it, comprising at least one filter material and at least one rebound element, and with a cleaning device, comprising at least one nozzle, which can be directed, for the removal of a filter cake, on the filter material by means of a cleaning medium perpendicularly and/or angularly in relation to the filter element, where, for the cleaning, the cleaning medium at least partially penetrates the filter material, and the rebound element deflects the cleaning medium at least partially for the renewed passage through the filter material, with at least partial removal of the filter cake at the same time. Advantageously, exactly one nozzle or nozzle block is associated with one filter element. 
     The filtering device according to the invention presents the great advantage that, due to the specific design of the filter element with at least one rebound element, a very effective removal of the filter cake that is being deposited on at least one filter material occurs, where suction nozzles that are known from the state of the art mentioned in the introduction are provided at the same time. The filtering device according to the invention can therefore be manufactured considerably more cost effectively, while the same good cleaning performance is achieved and also a more effective removal of the filter cake. Due to the feeding of the cleaning medium through the at least one nozzle perpendicularly and/or angularly in relation to the filter element, an individual and effective removal of the filter cake can occur, which is adapted to the specific properties of the medium to be cleaned, and takes into account the overall construction of the filtering device. The at least one nozzle can here be designed particularly so it is also movable and/or individually controllable. It is preferable for the cleaning device to present at least one nozzle row or else a nozzle field. Each of the individual nozzles of such a nozzle row or nozzle field design can here be designed to be movable, and it can be controlled separately; however, any desired combinations including fixed nozzles or consisting exclusively of fixed nozzles are conceivable. Here, the nozzles are directed perpendicularly on the filter element, the cleaning medium impacts perpendicularly on at least one filter material of the filter element, penetrating through the latter, where subsequently the cleaning medium is then reflected by the surface of the rebound element by approximately 180 degrees, as a function of the filter material used and its deflection of the cleaning medium as well as of the surface of the rebound element, where subsequently the cleaning medium then again penetrates through the filter material, clearing the filter cake at least partially or rinsing mud at least partially out of the filter element. 
     In an alternative embodiment for this, the nozzles are oriented at an angle of preferably approximately 5 to approximately 85 degrees, in relation to the filter element or its surface, so that the cleaning medium impacts the filter material of the filter element at a corresponding angle, penetrates through the filter material, and then is reflected from the surface of the rebound element at an angle that corresponds more or less to the rebound angle, as a function of the filter material used. The cleaning medium that has been reflected in this way again penetrates through the filter material, and it removes the mud or filter cake, which has been collected up or has deposited on or in the filter material of the filter element. Such an angular arrangement of the nozzles with respect to the surface of the filter element is particularly advantageous when the cleaning device is designed to be movable in a preferred embodiment, so that, in the direction of movement, the cleaning medium can be fed on the filter element and the filter material angularly, which results particularly in facilitating, particularly in accelerating, the removal from the filtering device of the cleaning medium that has become contaminated with the protection [sic; mud] or filter cake. 
     In another alternative embodiment, the cleaning device can also present nozzles that are oriented both vertically and angularly in relation to the surface of a filter element, where, for example, in an arrangement in the form of a nozzle row, first a nozzle row can also be provided that feeds the cleaning material perpendicularly on the filter element, and subsequently a nozzle row that discharges the cleaning medium on the filter element angularly in relation to the surface of the filter element, and particularly in the direction of movement in the case of a movable cleaning device. Naturally, the reverse arrangement is also conceivable. All possible combinations of arrangements of nozzles in the cleaning device as well as their orientation in view of the filter element are in accordance with the invention. 
     The cleaning medium is released out of the nozzles of the cleaning device, preferably under pressure, here preferably at a pressure of more than 3 bar, and more preferably at a pressure of more than 5 bar. As a result, the cleaning effect is increased, and the cleaning step is accelerated. 
     It is preferable for the filter element of the filtering device to present a cylindrical and/or flat design. Here, the cleaning device can present particularly several, i.e., at least two filter elements with cylindrical and/or flat design. Flat filter elements can be arranged here particularly in one or more rows, while cylindrical filter elements can be accommodated preferably as an individual piece or in groups of two, three or four, or in groups of a multiple of the above-mentioned groups, in a filtering device. It is advantageous here for a nozzle, or a nozzle block to be associated with a filter element of cylindrical design, where it is preferable furthermore for the filter element to be designed so it can be moved. Flat pursuant to the present invention means that the filter elements can be designed, for example, as flat cuboids, which may be square or rectangular. Any other design of the filter element pursuant to the present invention is, however, also possible. 
     A partial area of a surface of the filter element can serve as a rebound element. This rebound element of the filter element of the filtering device can be designed as a rebound metal plate, particularly one presenting any conceivable shape that is adapted to the circumstances, for example, quadrangular, cylindrical or also spherical. The rebound element can here present openings for the passage of the cleaned filtrate. For example, a construction is conceivable in which the filter element presents a filter material, for example, nonwoven or yarn, which is pulled onto a simple frame structure, where, behind this filter material, the rebound element in the form of a metal plate is arranged. Such an arrangement can also occur spherically, for example, where the rebound element then comes to lie in the interior, or else outside the sphere defined by the filter element, where a cleaning of a medium to be cleaned can then occur from the inside toward the outside, or from the outside toward the inside, depending on the arrangement of the filter material and of the rebound element. If the filter material itself presents sufficient stiffness and rigidity, then a frame structure that carries the filter material and confers its shape to the latter can also be omitted. This can be the case, for example, when using sintered metal bodies as filter material. 
     Pursuant to the present invention, it is also possible to provide several rebound elements next to each other, one after the other, or partially overlapping. It is particularly preferable for the rebound element to be formed by a filter housing, which is at least partially enclosed or arranged partially with the at least one filter material. The filter housing itself can present, particularly in a head area and/or foot area of the same, outlets that are arranged for releasing the cleaned filtrate, flanges for the attachment in the interior of a filtering device to achieve a reliable securing in the latter, as well as other needed means and elements. For example, the rebound element can be formed by a flat solid block, particularly one made of a metal and/or plastic material, or of an at least partially hollow cylinder, where the flat block or else the cylinder can be open at one or else at both ends for the discharge of the cleaned filtrate. On the upper surface or the peripheral surface of the block or the cylinder, the filter material is then arranged, at least in partial areas of said surface. Moreover, in the filter housing that is formed from the block or cylinder, at least one opening is provided, through which the filtrate can enter into the interior and be released from the filtering device according to the invention through outlets that are associated with the head areas or the foot areas. 
     It is particularly preferable for the surface of the rebound element to present an at least partially structured design. By structuring the surface of the rebound element, advantageously, on the one hand, a simplified and particularly also accelerated outflow of the cleaned filtrate is achieved, particularly also in a directed way, toward openings that are provided on the filter element, and, moreover, during the cleaning of the filtering device, the cleaning medium that impacts under pressure is also reflected or scattered at different angles, resulting in an increase in the cleaning effect. The structure of the surface of the rebound element can be of any conceivable design; for example, the surface can be simply embossed in the shape of a point or line, or its design can be wavy, for example. It is preferable for the surface to present a structure that is formed from at least two recesses that run parallel to each other, viewed in the direction of a longitudinal axis L of the rebound element. Between the recesses, it is preferable to arrange particularly rib-shaped embossments. The embossments, if of linear design, can also present gaps, so that the medium to be cleaned can move from one recess to the adjacent recess. The gaps can be offset with respect to adjacent embossments or arranged without offset. In particular, embossments can also be arranged in such a way on the surface of the rebound element that continuous linear, particularly rib-shaped, embossments alternate with embossments interrupted with gaps. The filter material is in contact with the embossments, so that the filtrate can be led through the recesses to openings, and be released. The recesses are designed preferably as grooves, which end shortly before or at the head area and/or foot area of the rebound element, particularly in the case of a design as a filter housing. The grooves can here present a uniform depth or a varying depth over their entire length; for example, they may also present an incline particularly toward an opening. In the recesses, openings can be provided, preferably at least two for each recess. 
     In an additional preferred embodiment, the surface structure of the rebound element presents at least one recess that runs diagonally to the longitudinal axis L, and which is also designed preferably as a groove. Here, recesses that run diagonally can also be combined with recesses that run parallel. The recesses are here preferably distributed uniformly over the entire surface of the rebound element that is covered with the filter material. If only a part of the rebound element is enclosed with a filter material, corresponding structures need to be applied only in the area of the application of the filter material. 
     In a flat or block-like design of the rebound element in the form of a filter housing, it is preferable here for the at least one recess that is arranged diagonally to the longitudinal axis L to end in the immediate vicinity or in the head area and/or foot area of the filter housing. The opposite end of the corresponding diagonally running recesses can here end in a longitudinal side of the flat, block-like filter housing. Accordingly, the diagonally running recesses can be arranged on a cylindrically designed filter body. The diagonally running recesses can here present a rectilinear design, but they can also present a radial, for example, quadrant, shape. However, any other design of the recess that runs at least in partial areas diagonally, i.e., angularly, in relation to the longitudinal axis L, is advantageous pursuant to the present invention. If the diagonally running recesses end in the vicinity or in the head area and/or foot area of the rebound element, openings should preferably be provided there for the passage of the cleaned filtrate, because here, due to the specific surface structure of the rebound element, the filtrate is transported through the recesses on the opening(s). The openings can be point-shaped, circular, slit-shaped, or of any other design. It is also possible in particular to arrange openings that are also distributed over the remaining surface of the rebound element, particularly in the recesses of the surface of the rebound element. 
     Depending on the design of the rebound element, the latter can present an at least partially structured surface on one side, or also on both sides. In a flat, block-like design or a cylindrical design of the rebound element, particularly as a part of a filter housing, it is preferable to provide the entire surface in a cylindrically designed rebound element, or both sides in a flat, block-like rebound element, with a surface structure in the area of the adjacent filter material. 
     The filter material is chosen preferably from a group comprising nonwovens, fibers, fabrics, yarns and/or sintered metal bodies. Here it is also particularly possible to provide combinations of different filter materials, including for the generation of a filtration gradient in the filter element. In particular, sintered metal bodies with an integrated gradient pattern and manufactured from mixtures of sintered metal powders and sintered metal fibers, including with inserted fabric structures, etc., can also be used. It is preferable, pursuant to the present invention, to use as filter material a yarn that consists of one or more fine/thin individual filaments. It is preferable to use at least a yarn as filter material, because, during the filtration and cleaning process, the yarns vibrate, and as a result they support the filtration, on the one hand, and also the cleaning due to a facilitated removal of the filter cake. The yarn preferably presents a textured design, which allows considerably more soiling particles to be caught. It is preferable for the individual elements of the yarn to present a diameter of up to approximately 1 mm, preferably up to approximately 0.5 mm, and even more preferably approximately to 0.01 mm. The yarn as well as other filter materials are used here preferably in at least two, and more preferably in more than two, layers. In this way, very fine filtrates can be obtained, regardless of whether they are gaseous or liquid. The cleaning device according to the invention connects the mode of operation of an edge cleaning filter with that of a depth filter. 
     It is preferable for the cleaning device to present a sled-type design. The cleaning process comprises the at least one nozzle, which is arranged preferably on a nozzle block. In this nozzle block, several nozzles can be arranged, including particularly together in a nozzle row, and also as a nozzle field. A sled-type design of the cleaning device is advantageous particularly in a flat design of the filter element for the filtering device. Otherwise the cleaning device can also comprise a cylindrically designed nozzle block with nozzles arranged on it. The cleaning device can be driven here preferably hydraulically, electrically or mechanically, or via a gearing, for example, a worm gear. Alternatively, one can also provide for the cleaning device to present a stationary design, and the filter elements are moved. This is particularly advantageous with a cylindrical design of the filter elements. It is preferable to associate at least one nozzle with each individual filter element housed in the housing. As a result, the cleaning performance can be increased further. Here it is particularly advantageous, in the case of flat filter elements, for a nozzle block, particularly one with a nozzle row, to be associated with each side of the filter element that is provided with the filter material. Alternatively, the nozzle blocks can also present, in the case of filter elements that are arranged in several rows next to each other or in another arrangement, several nozzles that point in different directions, for the purpose particularly of cleaning several filter elements at the same time. In a flat filter element with filter material arranged on both sides, facing nozzle blocks, which extend over the entire longitudinal direction of the filter material, can be associated with one or more filter elements, particularly in the case of filter elements arranged in several rows, and, during the cleaning of the filter element(s) for removing the filter cake or the mud, they can be moved on or in them over the entire surface of one or more filter elements. One can also provide for at least two filter elements to be associated with at least one nozzle. This may be the case, for example, if the nozzle block with the at least one nozzle has a design that allows rotation, particularly in the case of the use of cylindrical filter elements, or if the filter elements themselves present a design that allows rotation. 
     If the filter element presents a cylindrical design, then it is preferable for the filter elements to be movable, and for the cleaning device in the form of a cylindrical nozzle block with arranged nozzle to be stationary, where the latter device can also present a design that allows rotation. For example, if four filter elements in a group are arranged together on an approximately square base area, then a cylindrically designed nozzle block can be arranged in the middle between them and present a respective nozzle row that is directed onto each of the four filter elements. By the rotation of the filter elements, for example, via a gearing, particularly a worm gear that is arranged in an outlet area, it is alternatively also possible to achieve in this way a cleaning of the entire surface of the filter material of a cylindrically designed filter element by pressurized air or hydraulically, for example, in the case of a stationary, cylindrical nozzle block. However, the nozzle block may also present only one nozzle row, and a design that allows rotation. 
     At least one opening in filter elements with cylindrical or flat design can be arranged at each position of the surface of the area that is covered with filter material, particularly also on a head area and/or foot area of the rebound element that is covered with filter material. The openings can present a design of any possible shape, for example, a round or an angular opening cross section, slit-shaped, etc. 
     The present invention relates moreover to a filter element that comprises at least one rebound element and at least one filter material, where the rebound element presents an at least partially structured surface. For the rest, the filter element according to the invention presents the advantageous embodiments that have already been represented above, particularly concerning the surface structure. 
     Moreover, the invention relates to a method for cleaning of a particularly gas and/or fluid medium, particularly in industrial installations, where the medium is cleaned at least partially by at least one filter element according to the invention with an at least partially structured surface on the rebound element of the same. 
     Finally, the present invention relates to a method for the removal of a filter cake that has become deposited or mud that has collected on at least one filter element, comprising at least one filter material and at least one rebound element in a filtering device, where, over at least one nozzle of a cleaning device, a cleaning medium is directed perpendicularly and/or angularly, in relation to a surface of the rebound element, on the filter element, the cleaning medium penetrates through the at least one filter material, rebounds at least partially on the rebound element, and, at the time of a renewed passage through the filter material, removes the filter cake at least partially. The terms filter cake and/or mud that becomes deposited on or in the filter element are synonymous terms pursuant to the present invention. 
     It is preferable for the cleaning device to be moved during the release of the cleaning medium; in an alternative embodiment, at the time of the release of the cleaning medium, the at least one filter element is moved. However, combinations of these two designs are also possible. The cleaning medium is here preferably a liquid and/or gaseous medium, and it can represent particularly also mixtures of liquid, gaseous or liquid and gaseous media. Here, the cleaning medium is chosen in view of the properties of the medium to be cleaned. It can be, for example, water, pressurized air, oxygen, ammonia, an aliphatic hydrocarbon or else a hydrocarbon mixture, gasoline or a similar substance. However, the preliminary and post cleaning medium is also chosen in view of the circumstances. In the case of the cleaning of a gaseous mixture by the filtering device, it is preferable to use a liquid cleaning medium, which rinses the filter cake/mud out of the filter material. In the case of the filtration of the liquid medium with the filtering device according to the invention, it is preferable to use the cleaned medium itself as cleaning medium. 
     Before feeding the cleaning medium, it is advantageous to rinse out the remaining medium to be cleaned that is still present in the housing of the filtering device with a preliminary cleaning medium. The preliminary cleaning medium can here be fed via an advantageously separate feed of the filtering device, and it can be released through an outlet through which the cleaning medium as well flows out of the filtering device. It can also be fed particularly advantageously under pressure into the filtering device, where, in the inlet, a valve is then provided advantageously, through which the pressure of the fed cleaning medium can be controlled precisely. Corresponding valves can also be provided at the inlet of the cleaning medium, and also of the medium to be cleaned, which can also be fed under pressure into the filtering device according to the invention. Similarly, the outlets for the cleaned filtrate and/or the cleaning or preliminary cleaning medium can also be provided with a preferably controllable valve. However, any other types of shutoff devices, for example, ball cocks or similar parts, are also conceivable. Due to the additional step of the feeding of a preliminary cleaning medium, the subsequent cleaning with the cleaning medium is advantageously temporally shortened. Moreover, it is advantageous to rinse out any remaining to cleaning medium [sic; medium to be cleaned] that is still present in the housing of the filtering device by means of a post cleaning medium. The feeding can here occur analogously to the feeding for the preliminary cleaning medium; however, additional feeds can also be provided. The preliminary and/or post cleaning medium can be in liquid or gaseous form, preferably gaseous, and here it may also represent a mixture of different gases. 
     When using a yarn-shaped or other material that is oriented in a preferential orientation, it is advantageous to apply the cleaning medium parallel to the winding or drawing direction of the filter material. This results in a highly efficient cleaning of the filtering device according to the invention. 
     The rebound effect and/or outflow of the cleaning medium is increased advantageously by the rebound element by structuring the surface of the latter. On this subject, reference is made to the explanations given above. The structured surface of the rebound element thus allows a facilitated and more rapid outflow of not only the cleaned filtrate but also of the cleaning medium and/or the preliminary cleaning medium. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and additional advantages of the present invention are explained in further detail below in reference to the following figures. 
         FIG. 1   a : a perspective view of a filtering device according to the invention; 
         FIG. 1   b : a side view of a head side of the filtering device according to  FIG. 1   a  with partial sections; 
         FIG. 2 : a partially broken open perspective view of the filtering device according to  FIG. 1   a;    
         FIG. 3 : an additional broken open perspective view of the filtering device according to  FIG. 1   a;    
         FIG. 4 : a perspective view of a filter element without filter material; 
         FIG. 5 : a perspective, partially broken open view of a filter element according to the invention with filter material; 
         FIG. 6   a : a partially broken open perspective view of the filtering device according to  FIG. 1   a  in a starting cleaning position; 
         FIG. 6   b : a view of the head side of the partially broken open filtering device according to  FIG. 6   a;    
         FIG. 7 : the cleaning device according to  FIG. 1   a  in a partially broken open view in a middle cleaning position; 
         FIG. 8 : the filtering device according to  FIG. 1   a  in a partially broken open view in an end cleaning position; 
         FIG. 9 : an alternative embodiment of the filtering device according to the invention; 
         FIG. 10   a : a cylindrically designed filter element according to the invention without filter material; 
         FIG. 10   b : an alternative embodiment of a cylindrically designed filter element without filter material; 
         FIG. 11 : the filter element according to  FIG. 10   a , partially enclosed with filter material; 
         FIG. 12 : a cylindrically designed filter element in a cross-sectional view without filter material; 
         FIG. 13 : a partially broken open perspective view of the filtering device according to  FIG. 9  for explanation of the filtering process; 
         FIG. 14 : a partially broken open view of the filtering device according to  FIG. 9  for illustrating preliminary cleaning; and 
         FIG. 15 : the [sic] a partially broken open view of the filtering device according to  FIG. 9  for facilitating cleaning of the same. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     First, it must be stated beforehand that the characteristics shown in the figures are not limited to the individual embodiment. Rather, the characteristics that are indicated in each case in the description, including the description of the figures, and the drawing, can be combined to produce variants. In particular, the object of the present invention is not limited to the number of filter elements that are arranged in a housing in the filtering device according to the invention, or else with regard to the arrangement of the openings for the passage of the cleaned filtrate into the filter elements. 
       FIG. 1   a  shows a filtering device according to the invention, which overall bears a reference character  10 , with a housing  12 , which presents an approximately cuboid-shaped design. This housing  12  presents an inlet  24  with a valve V 1  for the feeding of a medium to be cleaned and corresponding outlets  26 . 1  and  26 . 2  with valves V 2  and V 3  that are associated with them. Moreover, the filtering device  10  presents an inlet  28  with a valve V 6  that is associated with it, and serves for the introduction of a preliminary cleaning medium, and a corresponding associated outlet  30  with a valve V 4  that is associated with it. Finally, via a feed  32  and a valve V 5  that is associated with it, a cleaning medium is fed into the filtering device via the feed lines  34 . 1  and  34 . 2  of the filter, where this cleaning medium can be released through the outlet  30  out of the housing  12  of the filtering device  10 . Moreover, in  FIG. 1   a , a pressure sensor  38  can be seen, which is connected to a filtrate receiving element  40 . 1 . The filtrate receiving element  40 . 1  is arranged on a longitudinal side of the housing  12  of the filtering device  10 , and correspondingly with the former element, an additional filtrate receiving element  40 . 2  is arranged on the opposite longitudinal side of the housing  12 . These filtrate receiving elements  40  are connected to the filter element, which is not represented in  FIG. 1   a , in the interior of the housing  12 , and they present a channel, not represented here, in which the pressure sensor  38  engages. 
     This construction of the filtrate receiving elements  40 . 1  and  40 . 2  can be seen particularly in  FIG. 1   b . There, the arrangement of a filter element  14  with outlets  44  on its two front sides can be seen. The filter element  14  here presents a flat and block-like design. The outlets  44  end in the filtrate channels  42 . 1  and  42 . 2  that are arranged in the filtrate receiving elements  40 . 1  and  40 . 2 . Moreover, in  FIG. 1   b , an additional pressure sensor  36  can be seen, which measures the pressure of a medium to be cleaned that flows into the housing  12  and is fed via the feed  24 . By measuring the pressure difference between the pressure sensors  36  and  38  in case of soiling of the filter element  14 , and in the case where a predetermined target value is reached, the feed of the medium to be cleaned is stopped by the valve V  1 , and then the cleaning process, which is explained below, can be started. The cleaning process can in principle also be started at any time with/without existing pressure difference pursuant to the present invention. 
       FIG. 2  shows a partially broken open perspective view of the filtering device  10  according to  FIG. 1   a , where one can see clearly that the arrangement of a total of five filter elements  14 . 1 ,  14 . 2 ,  14 . 3 ,  14 . 4  and  14 . 5  in a row also comprises the design of a cleaning device  20 , which comprises the feed line  32 , the valve V 5 , the feed lines  34 . 1  and  34 . 2  for the cleaning agent as well as the nozzle blocks  68 . 1 ,  68 . 2 ,  68 . 3 ,  68 . 4  and  68 . 5  that are arranged on the feed line  34 . 1 . These nozzle blocks are arranged correspondingly on the opposite side of the filter elements  14 . 1 - 14 . 5  on the feed line  34 . 2 . The nozzle blocks  68  thus present a paired arrangement and association in each case with one predetermined filter element  14 . Thereby, the nozzle block  68  can also present, for example, in the case of filter elements  14  that are arranged in rows next to each other, nozzles oriented in several directions, so that a nozzle block can clean several filter elements at the same time. The filter elements  14 . 1 - 14 . 5  are enclosed here on both sides with a filter material, preferably a textured yarn consisting of one or more very thin individual filaments, preferably in several layers. 
       FIG. 2  shows the feed of the medium  58  to be cleaned, indicated by several black arrows, via the feed  24  and the valve V 1  into the interior of the housing  12  of the filtering device  10 . The medium  58  to be cleaned here penetrates into the filter elements  14 . 1  and  14 . 5  through the filter material that is arranged on the elements, and, in the end, it is led via the channels  42 . 1  and  42 . 2 , which are arranged in the filter receiving elements  40 . 1  and  40 . 2 , to the outlets  26 . 1  and  26 . 2 , from which the cleaned filtrate  60  is then removed from the filtering device  10 . 
     The paired arrangement of these blocks  68  can be seen in greater detail in  FIG. 3 , where the arrangement will be described in greater detail here with a view to the filter element  14 . 5  and the nozzle block pair  68 . 5 . The filter elements  14 . 1 - 14 . 4  or the nozzle block pairs  68 . 1 - 68 . 4  present corresponding designs.  FIG. 3  is the arrangement of a nozzle row  22  with a plurality of fixed and/or movable nozzles, which release the cleaning medium perpendicularly or angularly in relation to the filter element  14 . The blocks  68 . 5  present a cuboid-shaped design, and they extend in their longitudinal direction over the entire surface of the area of the filter element  14 . 5  that is enclosed with a filter material. 
       FIG. 4  shows an individual filter element  14 , without filter material, the like of which is accommodated five times in the filtering device according to  FIG. 1   a . The filter element  14  presents, in a head area  54  and a head [sic; foot] area  56 , which present a flange-shaped design, three arranged outlets  44  in each case, through which cleaned filtrate is led to the channels  40 . 1  [sic;  42 . 1 ] and  40 . 2  [sic;  42 . 2 ], which are arranged in the filter receiving elements  40 . 1  and  40 . 2 . The surfaces  46 . 1  of the front side and  46 . 2  of the back side of the flat, block-like filter elements  14  according to  FIG. 4  present a structure where on said surfaces in each case a plurality of longitudinal recesses  48 , presenting a groove design, is arranged, so that they run parallel to each other, and are intersected by diagonally running recesses  50 . These diagonally running recesses  50  here are arranged in a rhombic pattern over the entire surface of the filter area  14  that is covered with a filter material, and accordingly they intersect the recesses  48  that run in parallel. The recesses  48  and  50  terminate in each case in the head area  54  or the foot area  56 . The head area  54  and the foot area  56  present in each case a slit-shape opening  52 , not shown in greater detail in  FIG. 4 , which extends over the entire width of the filter element  14 , for receiving the cleaned filtrate that is fed through the structured surface via the recesses  48  and  50  of these slit-shaped openings  52 . The rebound element  18  of the filter element  14  here is designed as a solid filter-housing body; in the flange-shaped design of the head area  54  and of the foot area  56 , corresponding hollow cavities or channels are provided, through which the cleaned filtrate is led to the outlets  44 . However, the opening  52  can also present any other type of design, in particular, several openings  52  can also be distributed over the entire surface of the rebound element  18 . The openings  52  can be provided particularly in the recesses  48  and  50 , where the rebound element  58  then presents a design that is hollow or else is provided with channels, so that the filtrate  60  that has been received through these openings can be led to the outlets  44 . 
       FIG. 5  now shows the mode of operation of the filter element  14 , where in said figure the filter material  16  is also clearly visible in a partially broken open view. The latter material is designed as a fibrous yarn, and encloses the solid body of the rebound element  18 . The medium to be cleaned  58 , as illustrated by arrows that impact the filter element  14  from the outside) [sic], flows through the filter material  16  on the filter element  14 , where the cleaned filtrate  60  that is illustrated by small arrows, is then led via the recesses  48  and  50  on the surface  46 . 1 , and also on the surface  46 . 2  facing the former surface, to openings  52  that are arranged in the head area  54  and the foot area  56 . The filtrate  60  that has thus been deflected by the surface  46 . 1  or  46 . 2  of the rebound element  18  leaves the filter element  14  through the outlets  44 . 
     The functioning of the cleaning step of the filtering device  10  according to the invention is explained in greater detail in reference to  FIGS. 6-9 .  FIG. 6   a  here shows a partially broken open view of the filtering device  10  according to  FIG. 1   a , where the cleaning device  20  is arranged in a starting position. The valves V 1 , V 2 , V 3  and V 6  are closed, and the valves V 4  and V 5  are opened. In  FIG. 6   a , the nozzle row  22  of the nozzle block  68  can be seen clearly, which is associated on the feed lines  34 . 1  and  34 . 2  in pairs with each filter element  14 . The cleaning device  20  is designed as a sled, and it is movable in the direction of an arrow  78 , but naturally also in the opposite direction to reach the starting position. The blocks  68  are, with respect to each one of the total five filter elements, in a starting position slightly in front of the longitudinal side of the filter element  14 . The cleaning medium  62  is led through the feed  32 , which is regulated by the valve V 5 , to the filtering device  10 . In this position, the valves V 1 -V 3 , which are open in the filter process proper, have to be closed, and the same applies to the valve V 6  that serves for feeding the preliminary cleaning medium. Only the valves V 5  and V 4  are open. The cleaning medium  62  that is mixed with mud/filter cake flows out of the housing  12  of the filtering device  10  via the valve V 4  and the outlet  30 .  FIG. 6   b  shows, in a side view, the construction and the position of the cleaning device  20  according to  FIG. 6   a , and also the arrangement of the pressure sensors  36  and  38  as well as the construction of the filtrate receiving elements  40 . 
       FIG. 7  now shows the cleaning device  20 , which is moved in the direction of the arrow  78 , in a middle position, in which the nozzle blocks  68  that are arranged in both sides of the filter body  14  have reached approximately the middle of the filter element  14  at the height of the middle outlet  44 . 
     In  FIG. 8  one can see the end position of the cleaning device  20 , in which the nozzle blocks  68  are finally moved over the entire lateral surface of the filter element  14 , and assume their end position between the adjacent filter elements  14 . All the cleaning medium  62  is removed through the outlet  30  of the filtering device  10 . Optionally, preliminary cleaning medium, particularly gaseous preliminary cleaning medium, can be fed again via the valve V 6  to the filtering device  10 , to remove residues of the cleaning medium  62  from the filtering device  10 . The cleaning device  20  could naturally also be designed so that only one nozzle block pair  68  is provided, which moves over all five filter elements  14  arranged in a row. However, as a result of the assignment of a total of five nozzle block pairs  68  to each filter element  14 , a considerable acceleration of the cleaning is achieved. After the completion of the cleaning, the cleaning device  20  is moved again into the starting position according to  FIG. 6   a.    
       FIG. 9  now shows an alternative embodiment of the filtering device  10  according to the invention, which, in contrast to the one shown in  FIG. 1   a , does not present flat filter elements  14 , but rather, as shown in  FIGS. 10-15 , presents cylindrically designed filter elements. As another difference compared to the filtering device shown in  FIG. 1 , the alternative embodiment shown in  FIG. 9  presents only one outlet  26 , which is provided with a valve V 2 , for the filtrate to be cleaned. Via the feed  32  and the valve V 3  that is associated with it, cleaning medium can be fed to the device  10 , and via the outlet  30  and the valve V 4  that is associated with it, it can be removed. Through the inlet  28  and the valve V 5  that is associated with it, preliminary cleaning medium can be fed to the device  10 . Finally, in contrast with the filtering device according to  FIG. 1   a , the alternative embodiment shown in  FIG. 9  presents a junction element  74 , in which the cleaned filtrate to be removed from the total of four cylindrical filter elements  14  (see  FIGS. 10-15 ) is united, and led to the outlet  26 . However, each cylindrical filter element chosen can also be associated with its own outlet  26 . 
     In  FIG. 10   a , the construction of the cylindrically designed filter element  14  shown without filter material can be seen. They present recesses  48  that are parallel and run in the longitudinal direction of the filter element  14  over the entire peripheral surface of the area of the filter element  14  that is to be covered with filter material, where, in the recesses  48 , circular or angular openings  52  are arranged in the shape of a circle along the periphery of the cylindrical filter element  14 , through which openings cleaned filtrate can enter into the interior of the cylindrical filter element  14 . Alternatively, one could provide, for example, openings  52  on each end of the grooves  48  in question in the head area and/or foot area  54  or  56 . A head area  54  presents a flange  72 . 1 , and a foot area  56  presents a flange  72 . 2 , by means of which the cylindrical filter element  14  is securely attachable in the device  10  according to  FIG. 9 . Moreover, the filter element  14  presents an outlet  44  for the cleaned filtrate. 
       FIG. 10   b  shows an alternative embodiment of a cylindrically designed filter element  14  with respect to that shown in  FIG. 10   a , which again is represented here without filter material. The filter element  14  here presents particularly in addition a worm gear  45 , through which the cylindrically designed filter element  14 , during use, can be moved rotatably in a filtering device  10 , as shown, for example, in  FIG. 9 , by means of appropriate engaging gear wheels, which are not shown. Moreover, a partial area of a surface  46  of the filter element  14  presents a structuring with recesses  48  and, between the latter, rib-shaped embossments  49  are arranged. The recesses  48  are here designed so that they start from a flange  72 . 1  in a head area  54  of the filter element  14  and run linearly to a second flange  72 . 2  in a foot area  56 , and similarly the corresponding embossments  49 . The embossments  49  are designed here in such a way that alternately embossments  49  are arranged that present gaps  47 , in  FIG. 10   b , for example, three offset gaps  47  for each embossment  49  or four gaps  47  for each embossment  49 , over the entire length between the flange  72 . 1  and  72 . 2 . By means of these gaps  47 , the filtrate can be led between adjacently arranged groove-shaped recesses  48 . In the recesses  48 , openings  52  are provided for the passage of the filtrate  52  [sic;  60 ] into the interior of the filter element  14 . In the process, several, for example, six or a plurality of such openings  52  can be distributed over the entire area of the structured surface  46  in recesses  48 . The openings  52  can also be arranged in the head area (flange  72 . 1 ) and/or the foot area (flange  72 . 2 ), for example, in the area of an extension of at least one recess  48 . 
       FIG. 11  shows the filter element according to  FIG. 10   a , now enclosed partially with a filter material  16  in the form of a textured yarn. Here, the arrows  58  illustrate the feeding of a medium to be cleaned, which penetrates through the filter material  16 , and which is fed cleaned, as filtrate  60 , illustrated by the arrows  60 , through the recesses  48  to the openings  52 , and finally it leaves the cylindrical filter element  14  via the opening of the outlet  44 . 
     The filter element  14  according to  FIGS. 10   a  and  11  is here designed to be open on one side. However, it is also entirely possible for the cylindrically designed filter element to present two outlets  44 , which are arranged on the opposite head areas  54  and foot areas  56 , so that the cleaned filtrate  60  can leave the filter element  14  on both front sides. 
       FIG. 12  shows the cylindrical filter element  14  according to  FIGS. 10   a  and  11  in a cross-sectional view, where the openings  52  with their associated opening channels  70  can be seen particularly clearly. The rebound element  18  here consists of a hollow body formed from a metal and/or plastic material. In the foot area  56 , the filter element  14  is closed, and, on the head area,  54 , the outlet  44  is arranged connected to the flange  72 . 1  located there. 
       FIGS. 13-15  now show the individual filtration, preliminary cleaning and cleaning steps, where the filtration step and the preliminary cleaning step are carried out accordingly with the device shown in  FIG. 1   a . The medium to be cleaned  58  passes through the inlet  24 , which is regulated by the valve V 1 , into the interior of the filtering device  10 , it penetrates through the filter material of the total of four filter elements  14  that are arranged so they face each other in an approximately square base area, is transferred via the openings  52 , which are not shown in greater detail in  FIG. 13  (see  FIGS. 10-12 ), as cleaned filtrate, into the interior of the filter elements  14 , the filtrate  60  is finally cleaned in the joining element  74 , and is removed through the common outlet  26  following the valve V 2  of the device  10 . If the pressure difference that is measured by the pressure sensors  36  and  38  now becomes so large that a predetermined target value is exceeded, the valves V 1  and V 2  are closed, and the preliminary cleaning or cleaning of the device  10  is set in motion; however, the process can also be started at any time with/without existing pressure difference. Naturally, it is also possible to provide more than or fewer than four filter elements  14 . 
       FIG. 14  shows the preliminary cleaning step, where a preliminary cleaning medium  64  is fed via the feed  28 , which is regulated by the valve V 5 , to the device  10 , while being preferably gaseous and under pressure, which results in any filtrate  60  or medium to be cleaned  58  that is still present in the interior of the device  10  being released via the outlet  64  [sic;  44 ], which is regulated by the valve V 4 , out of the device  10 . After a predetermined time period, the feed of the preliminary cleaning medium  64  is then interrupted by closing the valve V 5 , and the cleaning proper is set in motion. 
       FIG. 15  shows the cleaning of the device  10 , where the cleaning medium  62  is fed via the feed  32 , which is regulated by the valve V 3 , to a nozzle block  68  with nozzle rows  22 . The nozzle block  68  here presents a cylindrical design, and it presents at least one nozzle row  22  associated or corresponds with each of the four filter elements  14 , i.e., a total of at least four. The individual nozzles of the nozzle row  22  can here apply the cleaning medium  62  perpendicularly and/or angularly on the surface of the filter element  14 . The cleaning element  62  penetrates through the filter material  16  which at least partially covers the rebound element  18 , it penetrates again through the filter material  16  of the filter elements  14 , and it is subsequently removed again via the outlet  30 , which is regulated via the valve V 4 , out of the device  10 . Here, one provides for the nozzle block  68  to present a stationary design, and for the filter elements  14  to be movable, which is illustrated by the arrow  76 . The filter elements  14  here rotate about their main axis, so that the total surface of the filter elements  14  can be imbued uniformly by the cleaning medium  62  that flows out of the nozzle row  22 , and the cleaning medium  62  can also be reflected correspondingly on the rebound element  18  of the filter elements  14  by the rebound element  18 , and again penetrate through the filter material  16  of the filter elements  14 . After a predetermined time span, the rotation of the filter element  14  is then stopped, and the valve V 3  and the valve V 4  are closed. Then the device  10  is again available for cleaning a medium  58  to be cleaned. Optionally one can, before feeding the medium  58  to be cleaned (see  FIG. 13 ), reapply preliminary cleaning medium, particularly gaseous or liquid, according to  FIG. 14 , to displace residues of the cleaning medium  62  from the device  10 . The work procedure of the device according to the invention that is described above in reference to  FIGS. 13-15  and to the description, is then continued in a new cycle. 
     By means of the filtering device according to the invention, the filter element according to the invention, and the method according to the invention, an effective filtration of the cleaning medium is achieved, regardless of whether it is liquid and/or gaseous, as well as an effective cleaning by providing rebound elements.