Abstract:
In order to provide a device for treating a fluid containing solids which has been flushed back from a reversible flow filter, comprising a sedimentation device for separating solids from the flushed back fluid by a process of sedimentation in a sediment collecting region which enables solids to be removed in a manner free from filter-aids and which exhibits as small a degree of fluid loss as possible, it is proposed that the sediment collecting region is arranged to be subjected to a positive pressure and/or a negative pressure in order to remove residual fluid from the sediment collecting region.

Description:
RELATED APPLICATION 
       [0001]    The present disclosure relates to the subject matter disclosed in German utility model application No. 20 2007 005 082.8 of Apr. 5, 2007, which is incorporated herein by reference in its entirety for all purposes. 
       FIELD OF THE DISCLOSURE 
       [0002]    The present invention relates to a device for treating a fluid containing solids which has been flushed back from a reversible flow filter, wherein the device comprises a sedimentation device for separating solids from the flushed back fluid by a process of sedimentation in a sediment collecting region. 
       BACKGROUND 
       [0003]    Devices for treating flushed back fluid from a reversible flow filter wherein the quantity of back flushed fluid from the reversible flow filter is placed in a treatment bath or applied to a band filter system are known from the state of the art. Such treatment devices exhibit a high degree of fluid loss and/or require filter aids such as filter paper for example, for the purposes of removing the solids contained in the flushed back fluid. 
       SUMMARY OF THE INVENTION 
       [0004]    The object of the present invention is to provide a device for treating flushed back fluid from a reversible flow filter of the type specified hereinabove which enables solids to be removed in a manner free from filter-aids and which exhibits as small a degree of fluid loss as possible. 
         [0005]    In accordance with the invention, this object is achieved in the case of a device incorporating the features indicated in the preamble of Claim  1  in that the sediment collecting region is arranged to be subjected to a positive pressure and/or a negative pressure in order to remove residual fluid from the sediment collecting region. 
         [0006]    The device in accordance with the invention enables residual fluid to be removed from the sediment collecting region in a simple manner. For this purpose, it is sufficient to subject the sediment collecting region to a positive pressure and/or a negative pressure. The residual fluid removed from the sediment collecting region is then available again for renewed usage so that the device in accordance with the invention exhibits no or only a very low loss of fluid. 
         [0007]    The removal of the residual fluid from the sediment collecting region is accompanied by a process of drying the solids that have deposited in the form of a sediment in the sediment collecting region. Following the removal of the residual fluid, the dried solids are present in cleansed form, i.e. substantially free of residual fluid. These cleansed solids can be disposed of or recycled in a particularly simple manner. 
         [0008]    In accordance with one embodiment of the invention, the sedimentation device comprises a pressure applying means for subjecting the sediment collecting region to the positive pressure. Residual fluid which has accumulated in the sediment collecting region can be squeezed out of the sediment collecting region with the help of the positive pressure. 
         [0009]    Advantageously, the pressure applying means comprises a compressor for the production of the positive pressure. The device in accordance with the invention can thereby be operated without any auxiliary external facilities. 
         [0010]    It is particularly preferable, if a gaseous auxiliary medium, which is arranged to be supplied to the sediment collecting region for applying the positive pressure thereto, is arranged to be subjected to a pressure by means of the pressure applying means. The gaseous auxiliary medium enables the positive pressure to be transmitted to the sediment collecting region and then into the sediment collecting region in a particularly effective manner. A particularly efficient process for drying the solids is thereby ensured. 
         [0011]    It is particularly expedient if the auxiliary medium is formed by air. This makes for particularly secure and efficient operation of the device in accordance with the invention. 
         [0012]    It is expedient if the pressure applying means comprises a flow control device with the aid of which the supply of the auxiliary medium to the sediment collecting region is controllable. The quantity of auxiliary medium which is needed for the process of drying a certain amount of solid can thereby be set in a particularly efficient manner; 
         [0013]    Preferably, the pressure applying means comprises a supply line for supplying the auxiliary medium to the sediment collecting region. The supply line enables the auxiliary medium to be subjected to pressure even at a spatial distance from the sediment collecting region. 
         [0014]    Preferably, the residual fluid is arranged to be displaced from the sediment collecting region by the auxiliary medium. This has the advantage that the gaseous and thus dry auxiliary medium entirely replaces or at least substantially entirely replaces the residual fluid within the sediment collecting region thereby ensuring complete removal or at least substantially complete removal of the residual fluid from the sediment collecting region. 
         [0015]    Preferably, the positive pressure to which the sediment collecting region is arranged to be subjected amounts to at least approximately 1.1 bar absolute pressure. A comparatively small pressure difference of approximately 0.1 bar for example relative to an ambient pressure of approximately 1 bar for example is thus sufficient to enable the residual fluid to be removed from the sediment collecting region with the aid of a positive pressure. 
         [0016]    In accordance with one embodiment of the invention, the positive pressure amounts to at most approximately 1.4 bar absolute pressure. A pressure applying means of particularly simple construction can therefore be used. 
         [0017]    A particularly advantageous embodiment of the invention envisages that the sedimentation device should comprise an evacuating means for subjecting the sediment collecting region to the negative pressure. The evacuating means can be provided as an alternative or in addition to the previously described pressure applying means. If the sedimentation device comprises merely a pressure applying means or just an evacuating means then this enables the device in accordance with the invention to be of particularly simple construction. If the device in accordance with the invention comprises both a pressure applying means and an evacuating means, then the device in accordance with the invention can be operated in a particularly flexible manner. 
         [0018]    The evacuating means enables the sediment collecting region to be subjected to negative pressure so that residual fluid can be removed from the sediment collecting region, for example, by evaporating and/or sucking the residual fluid out of the sediment collecting region. 
         [0019]    Advantageously, the evacuating means comprises a vacuum pump. The negative pressure can thereby be made available without having to resort to external auxiliary facilities. 
         [0020]    It is expedient if the evacuating means comprises a blocking device with the aid of which the sediment collecting region and the evacuating means are selectively connectable to one another or are separable from each other. In this way, the timing period for which the sediment collecting region is subjected to the negative pressure can be controlled in a particularly simple manner. 
         [0021]    Preferably, the evacuating means comprises an evacuation line for discharging the residual fluid removed from the sediment collecting region. This enables the residual fluid to be transported away in a particularly simple manner. 
         [0022]    It is advantageous, if the residual fluid is evaporable by the application of the negative pressure. This enables the solids deposited in the form of a sediment in the sediment collecting region to be dried in a particularly efficient manner. 
         [0023]    In accordance with one embodiment of the invention, the negative pressure amounts to at least approximately 0.005 bar absolute pressure. Evacuating means of comparatively simple construction can thereby be used. 
         [0024]    It is expedient if the negative pressure amounts to at most approximately  0 . 050  bar absolute pressure. This thereby enables the solids in the sediment collecting region to be dried in a particularly efficient manner i.e. completely dried, or fully dried at least insofar as possible. 
         [0025]    In accordance with one embodiment of the invention, the sedimentation device comprises a discharging means for discharging the residual fluid removed from the sediment collecting region. The discharging means facilitates the handling and transportation of the residual fluid removed from the sediment collecting region. 
         [0026]    Preferably, the discharging means comprises a blocking device with the aid of which the sediment collecting region and the discharging means are selectively connectable to one another or are separable from each other. This enables the residual fluid to be discharged from the sediment collecting region at a desired point in time and for a desired period of time. 
         [0027]    It is expedient if the discharging means comprises a discharge line through which residual fluid is arranged to be supplied to a container for the fluid medium that is to be supplied to the reversible flow filter. This has the advantage that the residual fluid removed from the sediment collecting region is made available again in order to enable it to be filtered with the help of the reversible flow filter. 
         [0028]    As an alternative or in addition thereto, the discharging means may comprise a discharge line through which residual fluid is arranged to be supplied to a container for the filtrate from the reversible flow filter. This has the advantage that the residual fluid can be made available for further use without any temporal delay due to a renewed filtering process, for example, as a cleansing fluid, as a lubricant and/or as a cooling agent. 
         [0029]    A preferred embodiment of the invention envisages that the sedimentation device should comprise a filtering means for filtering the residual fluid removed from the sediment collecting region. With the help of the sedimentation device, filtered residual fluid can thereby be made available, such a fluid thus being particularly well suited for further use as a cleansing fluid as a lubricant and/or as a cooling agent. 
         [0030]    Preferably, the filtering means borders on the sediment collecting region. This has the advantage that not only can residual fluid removed from the sediment collecting region be filtered with the help of the filtering means, but in addition, the solids deposited in the form of a sediment in the sediment collecting region can be retained in the sediment collecting region with the help of the filtering means. 
         [0031]    Preferably, the filtering means is arranged on a closure element which closes a solid discharge opening of the sedimentation device. This has the advantage that the sedimentation device is of particularly compact construction. 
         [0032]    It is expedient if the filtering means comprises a sieve. This enables a robust filtering means to be provided which, moreover, can be thoroughly cleaned. 
         [0033]    It is particularly advantageous, if the filtering means is movable between a working position in which the filtering means closes an outlet opening of the sedimentation device, and a rest position in which the filtering means unblocks the outlet opening of the sedimentation device. This has the advantage that the filtering means can filter the residual fluid in its working position and that the filtering means can be thoroughly cleaned in its rest position. 
         [0034]    Preferably, the filtering means comprises a moving apparatus for moving the filtering means from the working position into the rest position. This facilitates the handling of the filtering means. 
         [0035]    It is particularly preferred that the sedimentation device should comprise a flushing means for flushing the filtering means. This thereby ensures the reliable long-term operation of the filtering means. 
         [0036]    In accordance with one embodiment of the invention, the filtering means is arranged to be flushed with a flushing gas. The flushing gas, compressed air for example, has a particularly low viscosity so that the filtering means will be cleaned particularly well when flushing the filtering means with the flushing gas. 
         [0037]    The cleaning process can be controlled in a particularly effective manner if the flushing gas supply comprises a flushing gas blocking device. 
         [0038]    If the flushing gas supply comprises a flushing gas line, the flushing gas can be stored at a place well removed from the filtering means and can be supplied from there to the filtering means. 
         [0039]    A further embodiment of the invention envisages that the flushing means should comprise a flushing liquid supply by means of which the filtering means is arranged to be flushed with a flushing liquid. Flushing the filtering means with a flushing liquid has the advantage that this prevents the filtering means from drying out. 
         [0040]    Advantageously, the flushing liquid supply comprises a flushing liquid blocking device in order to enable the supply of the flushing liquid to the filtering means to be controlled in an effective manner. 
         [0041]    If the flushing liquid supply comprises a flushing liquid line, the flushing liquid can be made available at a place well removed from the filtering means and can be supplied from there to the filtering means. 
         [0042]    Preferably, the sedimentation device comprises a sedimentation container. With the help of the sedimentation container, a volume can be made available in which solids can be separated from the flushed back fluid by a process of sedimentation in the sediment collecting region. 
         [0043]    In a preferred embodiment of the invention, the sediment collecting region is formed by a lower region of the sedimentation container when this is in the operational position. 
         [0044]    Preferably, the device comprises an aerator by means of which a container volume bounded by the sedimentation container is selectively connectable to an environment of the sedimentation container or the container volume is separable from the environment. The aerator enables ventilation of the sedimentation container to be effected in a particularly simple manner. By separating the container volume from the environment, it is possible to apply pressure to the container volume so that a sediment collecting region possibly formed in the lower region of the sedimentation container is arranged to be subjected to positive pressure. 
         [0045]    It is expedient, if the sedimentation device comprises a detecting device for detecting the level of a quantity of the flushed back fluid that is contained in the sedimentation container. With the help of this detecting device for example, it can be determined as to whether the quantity of the flushed back fluid contained in the sedimentation container falls below a certain minimum quantity. 
         [0046]    A further embodiment of the invention envisages that the sedimentation device should comprise a quantity of sediment detecting device for detecting the quantity of sediment that has collected within the sediment collecting region. It can thereby be determined for example as to whether a certain minimum quantity of solids has collected in the sediment collecting region so that the process of subjecting the sediment collecting region to the positive pressure and/or the negative pressure for the removal of the residual fluid from the sediment collecting region can be started. 
         [0047]    A particularly preferred embodiment of the invention envisages that the sedimentation device should comprise a solid discharge opening for discharging the solid that has deposited in the form of a sediment from the sediment collecting region and a closure element for closing the solid discharge opening. It is thereby possible to achieve a particularly simple process for discharging the solids from the sediment collecting region. 
         [0048]    Further features and advantages of the invention form the subject matter of the following description and the pictorial illustration of an exemplary embodiment. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0049]      FIG. 1  shows a schematic illustration of a filtering means for the filtration of a fluid medium containing solids; 
           [0050]      FIG. 2  a schematic partly sectional side view of a sedimentation device of the filtering means in  FIG. 1  in the initial state of the sedimentation device; 
           [0051]      FIG. 3  an illustration of the sedimentation device corresponding to  FIG. 2  in a back flushing phase of the filtering means; 
           [0052]      FIG. 4  an illustration of the sedimentation device corresponding to  FIG. 3  in a pressure applying phase of the sedimentation device; 
           [0053]      FIG. 5  an illustration of the sedimentation device corresponding to  FIG. 4  in an evacuation phase of the sedimentation device; 
           [0054]      FIG. 6  an illustration of the sedimentation device corresponding to  FIG. 5  in a solid discharge phase of the sedimentation device; 
           [0055]      FIG. 7  an illustration of the sedimentation device corresponding to  FIG. 6  in a first flushing phase of the sedimentation device; and 
           [0056]      FIG. 8  an illustration of the sedimentation device corresponding to  FIG. 7  in a second flushing phase of the sedimentation device. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0057]    Similar or functionally equivalent elements are designated by the same reference symbols in each of the Figures. 
         [0058]    A filtering means for the filtration of a fluid medium containing solids, an aqueous cleaner, an oil or an emulsion for example, which bears the general reference  100  and is illustrated in  FIG. 1  comprises a dirt tank  102  for receiving the medium requiring filtering which is connected to the dirt-side space  106  of a reversible flow filter  108  by means of a filter supply line  104 . As a supplement to the following explanation, reference is hereby expressly made to DE 20 2006 003 680 U1 from the same applicant in regard to the structure and the mode of functioning of the reversible flow filter  108 . 
         [0059]    A filter pump  110  for advancing the medium requiring filtering from the dirt tank  102  to the reversible flow filter  108  is arranged in the filter supply line  104 . 
         [0060]    The reversible flow filter  108  comprises a filter housing  112  having a substantially cylindrical upper section  114  and a downwardly tapering lower conical section  116  adjoined to the lower part of the upper section  114 . 
         [0061]    The upper section  114  of the filter housing  112  is divided by a partition wall  118  which is indicated by a broken line in  FIG. 1  into a filtrate-side space  120  that is located above the partition wall  118  and the dirt-side space  106  which is located below the partition wall  118 , whereby the interior of the lower section  116  of the filter housing  112  also counts as part of the dirt-side space  106  of the reversible flow filter  108 . 
         [0062]    Furthermore, a (not illustrated) filter cartridge is arranged in the filter housing  112 , said cartridge being rotatable about a vertical axis of rotation  126  by means of a motor  124  and it contains a plurality (not illustrated) of filter elements which are movable successively into a filter chamber  130  of the reversible flow filter  108  indicated by the broken lines by rotation of the filter cartridge about the axis of rotation  126 . 
         [0063]    On the filtrate-side, each of the filter chamber elements located in the filter chamber  130  is connected on the one hand to the filtrate-side space  120  of the filter housing  112  and on the other hand to a back flushing line  132  which leads from the filter chamber  130  to a back flushing valve  134 . Furthermore, the back flushing valve  134  is connected to a flushing line  136  which leads from the reversible flow filter  108  to a fluid inlet  138  (see  FIG. 2 ) of a sedimentation container  140 . 
         [0064]    A dirt-side inlet  142  of the reversible flow filter  108  which opens out into the dirt-side space  106  of the filter housing  112  is connected to the filter supply line  104 . 
         [0065]    A filtrate-side return outlet  144  of the reversible flow filter  108  which emerges from the filtrate-side space  120  of the filter housing  112  is connected by means of a filter return line  146  (see  FIG. 1 ) to a clean tank  148  for receiving the filtered medium. 
         [0066]    Furthermore, a compressed air supply  162  which is connected to a (not illustrated) source of compressed air opens out into the filtrate-side space  120  of the filter housing  112 . 
         [0067]    The conically converging lower section  116  of the filter housing  112  is arranged to be closed at its lower end by means of a coarse dirt valve  150 . 
         [0068]    Furthermore, the coarse dirt valve  150  is connected by a vertically running coarse dirt line  152  to the flushing line  136 , whereby the lower end of the coarse dirt line  152  serving as a coarse dirt outlet merges into a substantially horizontally running section of the flushing line  136  so that a coarse dirt collecting space  156  is formed within the flushing line  136  in the vicinity of the point of entry of the coarse dirt line  152 . 
         [0069]    A (not illustrated) metal sensor is arranged on the coarse dirt line  152  for the purposes of detecting the level to which the coarse dirt fills the coarse dirt line  152 . As a supplement to the preceding explanation, reference is hereby expressly made to DE 20 2006 003 680 U1 from the same applicant in regard to the arrangement and the mode of functioning of the metal sensor as well as in regard to the design of the coarse dirt collecting space  156  and its environment. 
         [0070]    A reverse flushing discharge valve  160  is arranged in the flushing line  136  downstream of the coarse dirt collecting space  156 , said valve being arranged to block access to the sedimentation container  140  illustrated in detail in  FIGS. 2 to 8 . 
         [0071]    The sedimentation container  140  comprises a container housing  164  having a substantially cylindrical upper section  166  and a downwardly tapering lower conical section  168  adjoined to the lower part of the upper section  166 . 
         [0072]    The flushing line  136  flows into the upper section  166  of the container housing  164  via the fluid inlet  138 . 
         [0073]    The container housing  164  bounds a container volume  170 . The sedimentation container  140  has a lower region  172  which comprises a sediment collecting region  174 . 
         [0074]    The sedimentation device illustrated in detail in  FIG. 2  comprises an aerator  176  having a ventilation valve  178 . The container volume  170  bounded by the sedimentation container  140  can be connected to an environment  180  of the sedimentation container  140  or be separated from the environment  180  by switching over the ventilation valve  178 . 
         [0075]    Furthermore, the sedimentation device illustrated in  FIG. 2  comprises a detecting device  182  for detecting the level to which a quantity of the fluid flushed back from the reversible flow filter  108  fills the sedimentation container  140 . 
         [0076]    A pressure applying means  184  is provided in order to enable the sediment collecting region  174  to be subjected to pressure. This comprises a compressor  186  which compresses air from the environment. Furthermore, the pressure applying means  184  comprises a pressure measuring unit  188  for measuring the pressure produced by the compressor  186  and also a flow control device  190  with the aid of which the supply of compressed air to the sediment collecting region  174  is controllable. Furthermore, the pressure applying means  184  comprises a supply line  192  which flows into the container volume  170  of the sedimentation container  140 . 
         [0077]    Furthermore, the sedimentation device illustrated in  FIG. 2  comprises an evacuating means  194  incorporating a vacuum pump  196  for the production of a vacuum. Furthermore, the evacuating means  194  comprises a blocking device  198  as well as an evacuation line  200 . The sediment collecting region  174  can be subjected to a negative pressure with the help of the evacuating means  194 . 
         [0078]    Furthermore, the sedimentation device comprises a discharging means  202  incorporating a blocking device  204  as well as a discharge line  206 . Residual fluid can be discharged from the sediment collecting region  174  with the help of the discharging means  202 . 
         [0079]    A filtering means  208  is provided for filtering the residual fluid removed from the sediment collecting region  174 . This said filter adjoins the lower part of the sediment collecting region  174 . The filtering means  208  is arranged on a closure element  210  which closes a solid discharge opening  212  of the sedimentation container  140 . Solids that have deposited in the form of a sediment in the sediment collecting region  174  can be discharged through the solid discharge opening  212  and supplied to a solid collecting container  214  which is illustrated in  FIG. 1  and in  FIGS. 6 and 7 . 
         [0080]    The closure element  210  comprises an upper cover part  216  as well as a cup-shaped base part  218  which is connected thereto. The base part  218  serves to accommodate a sieve  220 . The sieve  220  bounds an outlet opening  222  through which residual fluid can be discharged from the sediment collecting region  174  and supplied to the sieve  220 . 
         [0081]    The filtering means  208  comprises a moving apparatus  224  having a linear drive  226 . The linear drive  226  comprises a displaceable piston rod  228  which is connected in rotational manner at the free end thereof to the base part  218  of the closure element  210  by means of a joint  230 . The base part  218  of the closure element  210  is mounted on a static pivotal bearing  232  which is arranged on the cover part  216  of the closure element  210  and is rotatable about this pivotal bearing  232  (see  FIG. 6 ). 
         [0082]    Furthermore, as can be seen from  FIG. 2 , the sedimentation device comprises in addition a flushing means  234  for flushing the filtering means  208 . The flushing means  234  comprises a flushing gas supply  236  incorporating a flushing gas blocking device  238  and a flushing gas line  240 . 
         [0083]    Furthermore, the flushing means  234  comprises a flushing liquid supply  242  incorporating a flushing liquid blocking device  244  and a flushing liquid line  246 . 
         [0084]    The evacuation line  200 , the discharge line  206 , the flushing gas line  240  and the flushing liquid line  246  are connected via a common line  248  to a chamber  250  that is bounded by the base part  218  of the closure element  210 . 
         [0085]    In an alternative, not illustrated embodiment of the sedimentation device, at least two of the lines  200 ,  206 ,  240  and  246  are connected directly to the chamber  250 , i.e. without the intermediary of a common line  248 . 
         [0086]    The previously described filtering means  100  functions as follows: 
         [0087]    The fluid medium mixed with solids requiring filtering, for example an aqueous cleansing fluid, an oil or an emulsion is collected in the dirt tank  102 . 
         [0088]    From the dirt tank  102 , the medium requiring filtering is supplied to the dirt-side space  106  of the reversible flow filter  108  by the filter pump  110 . 
         [0089]    The inlet  142  of the reversible flow filter  108  runs substantially tangentially to the inner boundary wall of the filter housing  112  so that the medium requiring filtering moves through the interior of the filter housing  112  along a helical track. 
         [0090]    Upon entry of the medium requiring filtering into the reversible flow filter  108 , heavy dirt particles sink downwardly through the opened coarse dirt valve  150  and the coarse dirt line  152  into the coarse dirt collecting space  156  in the flushing line  136  where an accumulation of coarse dirt consequently forms during the filtering phase of the reversible flow filter  108 . 
         [0091]    During this filtering phase of the reversible flow filter  108 , the back flushing valve  134  and the reverse flushing discharge valve  160  are closed. 
         [0092]    The medium requiring filtering is supplied from the dirt-side space  106  of the reversible flow filter  108  through the filter element in the filter chamber  130  to the filtrate-side space  120  of the reversible flow filter  108 . 
         [0093]    From the filtrate-side space  120  of the reversible flow filter  108 , the filtrate then reaches the clean tank  148  via the filter return line  146 . 
         [0094]    During the passage through the filter element, the finer solid particles are held back between the dirt side and the clean side of the filter element in accord with the filtration rate of the filter element. 
         [0095]    When the maximum dirt retention capacity of the filter element is reached, a back flushing phase of the reversible flow filter  108  is initiated for the purposes of regenerating the filter element, i.e. a compressed-air-supported reverse flushing of the filtering medium is effected from the clean side to the dirt side. 
         [0096]    For the purposes of this back flushing process, the coarse dirt valve  150  is closed, and the reverse flushing discharge valve  160  in the flushing line  136  is opened. 
         [0097]    Subsequently, the back flushing valve  134  is opened for a brief period, and the filtrate-side space  120  of the reversible flow filter  108  is subjected to compressed air by means of the compressed air supply  162  so that filtrate is flushed out with the support of the compressed air from the filtrate-side space  120  of the reversible flow filter  108  through the filtering medium of the filter element  128  back into the dirt-side space  106  of the reversible flow filter  108 , from there, into the back flushing line  132  and from there, through the opened back flushing valve  134  into the flushing line  136 . 
         [0098]    The impurities detached during the reverse flushing of the filter element  128  also enter the flushing line  136  together with the filtrate being used as a flushing medium. 
         [0099]    The flushed back fluid also passes through the coarse dirt collecting space  156  and rinses the coarse dirt accumulated there through the opened reverse flushing discharge valve  160  into the sedimentation container  140 . (see  FIG. 3 ). 
         [0100]    The reverse flushing discharge valve  160  is opened during each back flushing phase for a period of approximately  1  sec to  3  sec for example. 
         [0101]    The back flushing phase of the reversible flow filter  108  is terminated by the closure of the back flushing valve  134  and the reverse flushing discharge valve  160  as well as by the renewed opening of the coarse dirt valve  150 , whereupon a new filtering phase of the reversible flow filter  108  begins. 
         [0102]    The back flushing phase of the reversible flow filter  108  can be initiated when a given maximum level of the coarse dirt in the coarse dirt line  152  is detected by means of the metal sensor on the coarse dirt line  152 . 
         [0103]    As an alternative or in addition thereto, a back flushing phase of the reversible flow filter  108  can be initiated when the difference in pressure between the dirt side and the clean side of the filter element exceeds a given maximum value. 
         [0104]    The treatment of the fluid flushed back in the course of the back flushing phase takes place in the sedimentation container  140  illustrated in  FIGS. 2 to 8 . 
         [0105]    As can be seen from  FIG. 3 , the fluid inlet  138  is aligned substantially tangentially relative to the inner wall of the container housing  164  so that the flushed back fluid enters the interior of the sedimentation container  140  along a helical track  252 . 
         [0106]    The solids (coarse dirt and the impurities flushed back from the filter element), which are contained in the flushed back fluid and bear the reference symbol  254  in  FIG. 3  and which are within the flushed back fluid bearing the reference symbol  256  in  FIG. 3 , are deposited in the form of a sediment in the sedimentation container  140  and settle in the sediment collecting region  174 . 
         [0107]    The ventilation valve  178  of the aerator  176  is opened during the back flushing phase illustrated in  FIG. 3 . The flow control device  190  of the pressure applying means  184  is closed. Furthermore, the blocking device  198  of the evacuating means  194 , the blocking device  204  of the discharging means  202  as well as the flushing gas blocking device  238  and the flushing liquid blocking device  244  of the flushing means  234  are closed. 
         [0108]    At the conclusion of the back flushing phase, the reverse flushing discharge valve  160  and the ventilation valve  178  are closed. From then on, the sediment collecting region  174  can be subjected to pressure. This application of pressure phase is described hereinafter with reference to  FIG. 4 . 
         [0109]    The blocking device  204  of the discharging means  202  is opened for the purposes of initiating the application of pressure phase. At the same time, the flow control device  190  of the pressure applying means  184  is opened. In consequence, compressed air that is effective as an auxiliary medium and is produced with the help of the compressor  186  is fed via the supply line  192  into the container volume  170  of the sedimentation container  140 . The absolute pressure of the compressed air being introduced can amount to between approximately 1.1 bar and 1.4 bar. 
         [0110]    Due to the process of applying pressure in the form of compressed air to the fluid  256  that is illustrated in  FIG. 3 , the fluid  256  is squeezed out of the container volume  170  and out of the sediment collecting region  174  and is supplied by way of the outlet opening  222  to the filtering means  208 . Hereby, the quantity of compressed air introduced into the sediment collecting region  174  displaces the residual fluid adhering to the solids  254 . The residual fluid is filtered with the help of the sieve  220  of the filtering means  208  and enters the discharge line  206  via the chamber  250  and the common line  248  and from there, reaches the dirt tank  102  or the clean tank  148  via the opened blocking device  204 . 
         [0111]    The application of pressure phase described above can be monitored with the help of the detecting device  182 . This phase is concluded when the detecting device  182  can no longer detect liquid in the sedimentation container  140  or if the detecting device  182  can no longer detect liquid and it is terminated after the elapse of a certain period of time (drying time) commencing from this time point. 
         [0112]    At the conclusion of the application of pressure phase, the blocking device  204  and the flow control device  190  are closed, and the ventilation valve  178  is opened. 
         [0113]    The sediment collecting region  174  could also be subjected to a negative pressure. This is described hereinafter with reference to  FIG. 5 . For the purposes of initiating the evacuation phase, the ventilation valve  178  is closed. Subsequently, the blocking device  198  of the evacuating means  194  is opened. 
         [0114]    A vacuum can then be produced with the help of the vacuum pump  196 . The vacuum pump  196  is in contact with the sediment collecting region  174  via the opened blocking device  198 , the evacuation line  200  as well as the common line  248  and via the chamber  250  and the openings (without reference symbols) in the sieve  220 . In this way, a vacuum is produced within the sediment collecting region  174  so that the sediment collecting region is subjected to a negative pressure. The absolute pressure of the negative pressure can amount to between approximately 0.005 bar and approximately 0.050 bar. 
         [0115]    By subjecting the sediment collecting region  174  to the negative pressure, any residual fluid present in this region and which may be adhering to the solids  254  for example will evaporate. The residual fluid is thereby removed from the sediment collecting region  174 . The length of time for which the sediment collecting region  174  is subjected to negative pressure is variable and, in particular, can be adjusted in accord with the quantity of residual fluid that is to be removed and/or the quantity of solids that is to be dried. 
         [0116]    After the abovementioned absolute pressures have been reached and a certain time has elapsed, the blocking device  198  is closed for the purposes of concluding the evacuation phase. Subsequently, the ventilation valve  178  is opened so that the pressure prevailing in the container volume  170  and in the sediment collecting region  174  will correspond to the pressure in the environment  180  of the sedimentation container  140 . 
         [0117]    In order to remove residual fluid from the sediment collecting region  174 , it can be sufficient for just the application of pressure phase that was previously described with reference to  FIG. 4  to be gone through. It may likewise be sufficient for merely the evacuation phase that was previously described with reference to  FIG. 5  to be gone through. However, a particularly effective process for drying the solids  254  that have deposited in the form of a sediment in the sediment collecting region  174  is obtained if both the application of pressure phase and the evacuation phase are executed. Preferably thereby, the evacuation phase is performed after the application of pressure phase. 
         [0118]    In order to remove dried solid  254  from the sediment collecting region  174 , the filtering means  208  can be moved from the working position thereof that is illustrated in  FIG. 5  into a rest position which is illustrated in  FIG. 6  after ventilating the sedimentation container  140  by opening the ventilation valve  178 . To this end, the moving apparatus  224  is controlled in such a way that the piston rod  228  of the linear drive  226  moves the joint  230  so that the base part  218  of the closure element  210  pivots relative to the cover part  216  about the fixed articulated bearing  232 . The solid discharge opening  212  is thereby unblocked so that dried solid  254  falls under the effect of the force of gravity from the sediment collecting region  174  into the solid collecting container  214 . 
         [0119]    The filtering means  208  can be cleaned by flushing. A cleaning process using a flushing gas is described hereinafter with reference to  FIG. 7 . 
         [0120]    The process of cleaning the filtering means  208  with a flushing gas, preferably compressed air, is particularly simple if the filtering means  208  adopts its rest position illustrated in  FIG. 7 . For the purposes of initiating the flushing process, the flushing gas blocking device  238  is opened so that a flushing gas that is made available from a not illustrated source of flushing gas can be supplied to the back of the sieve  220  via the flushing gas line  240 , via the common line  248  and via the chamber  250 . 
         [0121]    The cleaning of the sieve  220  takes place mechanically i.e. in that the stream of flushing gas removes solids  254  adhering to the sieve  220 . The solids  254  removed from the sieve  220  fall into the solid collecting container  214 . The flushing gas blocking device  238  is closed after a blowing period which is adjustable as necessary. Subsequently, the filtering means is brought back into the working position thereof with the help of the moving apparatus  224 , see  FIG. 8 . 
         [0122]    The filtering means  208  can also be cleaned with the help of a flushing liquid  258 . This is described with reference to  FIG. 8 . 
         [0123]    In order to rinse the filtering means  208  with flushing liquid  258 , the flushing liquid blocking device  244  is opened so that flushing liquid made available from a not illustrated source of flushing liquid can be fed into the chamber  250  with the help of the flushing liquid line  246  and the common line  248 . From there, the flushing liquid  258  passes through the openings in the sieve  220  of the filtering means  208  and into the sediment collecting region  174 . The sieve  220  is thereby cleaned. In order to prevent the sieve  220  from drying out or the sieve  220  from becoming clogged with solids  254 , provision can be made for the flushing liquid  258  to remain in the sedimentation container  140 .