Abstract:
In order to provide a filter device for filtering a fluid medium containing solids, comprising a backflushing filter and a flushing line, by means of which fluid backflushed during a backflushing phase from the backflushing filter can be supplied to a further treatment mechanism, in which the discharging of dirt from the backflushing filter is simplified, it is proposed that the backflushing filter should have a coarse dirt outlet which is connected to the flushing line so that coarse dirt which has arrived through the coarse dirt outlet into the flushing line can be supplied to the further treatment mechanism together with the backflushed fluid during the backflushing phase.

Description:
RELATED APPLICATION 
     This application is a continuation application of PCT/EP2007/001571 filed Feb. 23, 2007, the entire specification of which is incorporated herein by reference. 
    
    
     FIELD OF THE DISCLOSURE 
     The present invention relates to a filter device for filtering a fluid medium containing solids, the filter device comprising a backflushing filter and a flushing line, by means of which backflushed fluid can be supplied from the backflushing filter to a further treatment mechanism during a backflushing phase. 
     BACKGROUND 
     Filter devices of this type are known from the prior art. 
     In known filter devices of this type, the fluid which is backflushed during the backflushing phase, on the one hand, and coarse dirt which has accumulated in the backflushing filter, on the other hand, are supplied by means of separate disposal lines to a collecting container. 
     The present invention is based on the object of providing a filter device of the type mentioned at the outset, in which the discharge of dirt from the backflushing filter is simplified. 
     SUMMARY OF THE INVENTION 
     This object is achieved according to the invention in a filter device with the features of the preamble of claim  1  in that the backflushing filter has a coarse dirt outlet which is connected to the flushing line, so that coarse dirt which has arrived in the flushing line through the coarse dirt outlet can be supplied together with the backflushed fluid to the further treatment mechanism during the backflushing phase. 
     In the solution according to the invention, the flushing line for the fluid which has been backflushed during the backflushing phase and the coarse dirt outlet for discharging coarse dirt from the backflushing filter are connected to one another, so the backflushed fluid and the coarse dirt from the connection point of the coarse dirt outlet and flushing line are supplied in a common line to the further treatment mechanism. Since the coarse dirt is located in the flow path of the fluid from the backflushing filter which has been backflushed during the backflushing phase, the accumulated coarse dirt is transported in a simple and effective manner to the further treatment mechanism without the supply of additional fluid being necessary for this. 
     The fluid consumption of the filter device is significantly reduced as a result. 
     The filter device according to the invention is suitable, in particular, for use in cleaning systems with aqueous cleaners, oils and/or emulsions. 
     The solids contained in the fluid medium to be filtered may, in particular, comprise ferromagnetic solids. 
     In a preferred configuration of the invention, it is provided that the course dirt outlet can be closed by means of a coarse dirt valve. 
     It may also be provided that the course dirt outlet opens into a substantially horizontally extending portion of the flushing line. This portion then forms a coarse dirt collecting chamber of the filter device. 
     In order for it to be achieved that a backflushing phase of the backflushing filter is always initiated when a certain quantity of coarse dirt has accumulated in a coarse dirt collecting chamber of the filter device, it may be provided that the filter device comprises a sensor, by means of which the filling level of the coarse dirt collecting chamber in the coarse dirt outlet and/or in the flushing line can be detected. 
     A sensor of this type may be configured, in particular, as a metal sensor. 
     The flushing line may then have a backflushing valve which is arranged upstream of the mouth of the coarse dirt outlet into the flushing line. 
     Furthermore, the flushing line may have a discharge valve which is arranged downstream of the mouth of the coarse dirt outlet and therefore blocks or clears the access to the further treatment mechanism. 
     In a preferred configuration of the invention, the backflushing filter is configured as an automatic backflushing filter, the backflushing phase of which is automatically initiated when the dirt receiving capacity of a filter element of the backflushing filter has been exhausted and/or a certain quantity of coarse dirt has accumulated in the coarse dirt collecting chamber. 
     The further treatment mechanism for further treatment and processing of the backflushed fluid with the contaminants contained therein, in particular the coarse dirt contained therein, may, in particular, comprise a sedimentation device and/or a solids separator. 
     The present invention is based on the further object of providing a filter method for filtering a medium containing solids by means of a backflushing filter, which simplifies the discharge of dirt from the backflushing filter. 
     This object is achieved according to the invention by a filter method for filtering a medium containing solids by means of a backflushing filter, comprising the following method steps:
         discharging coarse dirt from the backflushing filter through a coarse dirt outlet into a flushing line during a filtering phase;   backflushing the backflushing filter and supplying backflushed fluid from the backflushing filter together with coarse dirt which has accumulated in the flushing line to a further treatment mechanism during a backflushing phase.       

     Since, in the method according to the invention, the coarse dirt is flushed together with the backflushed fluid from the backflushing filter to the further treatment mechanism, the coarse dirt is transported in a very efficient manner to the further treatment mechanism without the supply of additional fluid being necessary for this. 
     Particular configurations of the filter method according to the invention are the subject of the dependent claims  10  to  15 , the advantages of which have already been described above in conjunction with the particular configurations of the filter device according to the invention. 
     Further features and advantages of the invention are the subject of the following description and the graphical view of an embodiment. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a schematic view of a filter device for filtering a fluid medium containing solids; 
         FIG. 2  shows a partially sectional side view of a backflushing filter with a coarse dirt outlet and a flushing line of the filter device from  FIG. 1 , during a filtering phase of the backflushing filter; 
         FIG. 3  shows a view of the backflushing filter corresponding to  FIG. 2  with the coarse dirt outlet and the flushing line during a backflushing phase of the backflushing filter; 
         FIG. 4  shows a schematic, partially sectional side view of a sedimentation device of the filter device from  FIG. 1  in a sedimentation phase of the sedimentation device; 
         FIG. 5  shows a view of the sedimentation device corresponding to  FIG. 4  in a sediment and clear phase discharge phase of the sedimentation device; 
         FIG. 6  shows a view of the sedimentation device corresponding to  FIG. 5 , at the end of the clear phase discharge phase of the sedimentation device; and 
         FIG. 7  shows a view of the sedimentation device corresponding to  FIG. 6 , in a screen flushing phase of the sedimentation device. 
     
    
    
     The same or functionally equivalent elements are designated by the same reference numerals in all the figures. 
     DETAILED DESCRIPTION OF THE INVENTION 
     A filter device designated as a whole by  100  and shown in  FIG. 1 to 7  for filtering a fluid medium containing solids, for example an aqueous cleaner, an oil or an emulsion, comprises a dirt tank  102  for receiving the medium to be filtered, which is connected to a dirt-side compartment  106  of a backflushing filter  108  by means of a filter supply line  104 . 
     A filter pump  110  for conveying the medium to be filtered from the dirt tank  102  to the backflushing filter  108  is arranged in the filter supply line  104 . 
     The structure of the backflushing filter  108  can be seen in detail from  FIGS. 2 and 3 . 
     The backflushing filter  108  comprises a filter housing  112  with a substantially cylindrical upper portion  114  and a lower portion  116 , which tapers conically downwardly, adjoining the bottom of the upper portion  114 . 
     The upper portion  114  of the filter housing  112  is separated by a horizontal partition  118  into a filtrate-side compartment  120  located above the partition  118  and the dirt-side compartment  106  located below the partition  118 , the interior of the lower portion  116  of the filter housing  112  also being included with the dirt-side compartment  106  of the backflushing filter  108 . 
     A filter insert  122  is also arranged in the filter housing  112  and can be rotated by means of a motor  124  about a vertical axis  126  of a rotation and contains a plurality of filter elements  128 , which, by rotating the filter insert  122  about the axis  126  of rotation, can be moved one after the other into a filter chamber  130  of the backflushing filter  108 . 
     The filter element  128  respectively located in the filter chamber  130  is, on the filtrate side, connected to the filtrate-side chamber  120  of the filter housing  112  and, on the dirt side, to a backflushing line  132 , which leads from the filter chamber  130  to a backflushing valve  134 . The backflushing valve  134  is furthermore connected to a flushing line  136  which leads from the backflushing filter  108  to a fluid inlet  138  (see  FIG. 4 ) of a sedimentation container  140 . 
     A dirt-side feed  142 , opening into the dirt-side compartment  106  of the filter housing  112 , of the backflushing filter  108  is connected to the filter supply line  104 . 
     A filtrate-side return  144  opening into the filtrate-side compartment  120  of the filter housing  112 , of the backflushing filter  108  is connected by means of a filter return line  146  (see  FIG. 1 ) to a clean tank  148  to receive the filtered medium. 
     Furthermore, a compressed air supply  162 , which is connected to a compressed air source (not shown), opens into the filtrate-side compartment  120  of the filter housing  112 . 
     The conically tapering lower portion  116  of the filter housing  112  can be connected at its lower end by means of a coarse dirt valve  150 . 
     The coarse dirt valve  150  is furthermore connected to the flushing line  136  by means of a vertically extending coarse dirt line  152 , the coarse dirt line  152  being used as a coarse dirt outlet opening at its lower end into a substantially horizontally extending portion  154  of the flushing line  136 , so a coarse dirt collecting chamber  156  is formed in the flushing line  136  in the region of the mouth of the coarse dirt line  152 . 
     A metal sensor  158  to detect the filling level of the coarse dirt in the coarse dirt line  152  is arranged on the coarse dirt line  152 . 
     Arranged downstream of the coarse dirt collecting chamber  156  in the flushing line  136  is a backflushing discharge valve  160 , by means of which the access to the sedimentation container  140  shown in detail in  FIG. 4 to 7  can be blocked. 
     The sedimentation container  140  comprises a container housing  164  with a substantially cylindrical upper portion  166  and a lower portion  168  tapering conically downwardly and adjoining the bottom of the upper portion  166 . 
     The flushing line  136  opens into the upper portion  166  of the container housing  164  by means of the fluid inlet  138 , specifically above a fluid level  170  in the sedimentation container  140 . 
     The lower end of the conically tapering portion  168  of the sedimentation container  140  opens into a sluice device designated as a whole  172 , which comprises an upper sluice valve  174  adjoining the sedimentation container  140 , a lower sluice valve  176  forming a lower termination of the sluice device  172  and a sluice chamber  178  arranged between the upper sluice valve  174  and the lower sluice valve  176 , the inner chamber of which sluice chamber forms a sediment collecting region. 
     The lower sluice valve  176  may be formed as a slide valve, in particular. 
     The lower sluice valve  176  is furthermore connected by means of a sediment discharge line  180  to an inlet of a solids separator  182  (see  FIG. 1 ). 
     The solids separator  182  is used to separate the remaining fluid medium containing sediment coming from the sluice chamber  178  from the solids portion of the sediment. 
     The solids separator  182  may, in particular, be constructed and function in the manner of the magnetic solids separator described in WO 2004/041438 A1. Reference is expressly made here to WO 2004/041438 A1 in relation to the structure and the mode of functioning of a solids separator of this type. 
     A residual fluid return line  186  leads from a fluid outlet  184  of the solids separator  182  to the dirt tank  102 . 
     The solids fraction of the sediment from the sluice chamber  178  separated from the residual fluid in the fluids separator  182  arrives in a solids collecting container  187 . 
     Furthermore, arranged substantially centrally in the sedimentation container  140  is a flushing tube  188  which extends along a substantially vertical tube axis through a lid  190  of the sedimentation container  140  into the interior thereof into the lower portion  168  of the container housing  164  and opens there into the inner chamber of the sedimentation container  140  at a point located below the fluid level  170 . 
     The mouth of the flushing tube  188  is closed by a screen  192  at the lower end thereof. 
     The upper end of the flushing tube  188  is closed by a sealing plate  193 . 
     A starting portion  194  arranged coaxially with respect to the flushing tube  188 , of a clear phase return line  196 , which passes through the sealing plate  193  and leads from the sedimentation container  140  to the dirt tank  102 , extends inside the flushing tube  188  (see  FIG. 1 ). 
     A check valve  198  and a through-flow regulator  200  are arranged in the clear phase return line  196 . 
     A compressed air supply line  202 , in which a compressed air valve  204  and a pressure regulator  206  are arranged, furthermore opens into the part of the interior of the sedimentation container  140  located above the fluid level  170 . 
     The compressed air supply line  202  is connected to a compressed air source (not shown). 
     Furthermore, a ventilation line  208 , in which a ventilation valve  210  is arranged, opens into the part of the interior of the sedimentation container  140  located above the fluid level  170 , so that the interior of the sedimentation container  140  can be ventilated with ambient air when the ventilation valve  210  is open. 
     Furthermore, the sedimentation container  140  is provided with a level probe  212  to detect the fluid level  170  inside the sedimentation container  140 . 
     The filter device  100  described below functions as follows: 
     The fluid medium mixed with solids to be filtered off, for example an aqueous cleaning fluid, oil or emulsion, is collected in the dirt tank  102 . 
     The medium to be filtered is supplied from the dirt tank  102  by means of the filter pump  110  to the dirt-side compartment  106  of the backflushing filter  108 . 
     As can be seen from  FIG. 2 , the supply  142  of the backflushing filter  108  runs substantially tangentially to the inner boundary wall of the filter housing  112 , so the medium to be filtered moves in a helical path  214  through the interior of the filter housing  112 . 
     On entry of the medium to be filtered into the backflushing filter  108 , heavy dirt particles sink downward through the opened coarse dirt valve  150  and the coarse dirt line  152  into the coarse dirt collecting chamber  156  in the flushing line  136 , where a coarse dirt accumulation  215  forms as a result during the filtering phase of the backflushing filter  108  (see  FIG. 2 ). 
     During this filtering phase of the backflushing filter  108  shown in  FIG. 2 , the backflushing valve  134  and the backflushing discharge valve  160  are closed. 
     The medium to be filtered is supplied from the dirt-side chamber  106  of the backflushing filter  108  through the filter element  128  located in the filter chamber  130  to the filtrate-side chamber  120  of the backflushing filter  108 . 
     The filtrate arrives from the filtrate-side chamber  120  of the backflushing filter  108  by means of the filter return line  146  into the clean tank  148 . 
     When passing through the filter element  128 , the finer solids particles are held back between the dirt side and the clean side of the filter element  128  according to the filter fineness of the filter element  128 . 
     When the maximum dirt receiving capacity of the filter element  128  is reached, a backflushing phase of the backflushing filter  108  shown in  FIG. 3  is initiated to regenerate the filter element  128 , i.e. a compressed air-assisted backflushing of the filter medium from the clean side to the dirt side. 
     The coarse dirt valve  150  is closed for this backflushing process, and the backflushing discharge valve  160  in the flushing line  136  is opened. 
     The check valve  134  is then briefly opened, and the filtrate side chamber  120  of the flushing filter  108  is acted upon by compressed air by means of the compressed air supply  162 , so that filtrate is flushed from the filtrate-side compartment  120  of the backflushing filter  108 , assisted by compressed air, by the filter medium of the filter element  128  back into the dirt-side chamber  106  of the backflushing filter  108 , from there into the backflushing line  132  and from there through the opened backflushing valve  134  into the flushing line  136 . 
     Together with the filtrate to be used as the flushing medium, the contaminants detached from the filter element  128  during the backflushing also arrive in the flushing line  136 . 
     The backflushed fluid also arrives through the coarse dirt collecting chamber  156  and flushes the coarse dirt accumulated there through the opened backflushing discharge valve  160  into the sedimentation container  140 . 
     The backflushing discharge valve  160  is open for a period of about 1 s to 3 s, for example, during each backflushing phase. 
     The backflushing phase of the backflushing filter  108  is ended by closing the backflushing valve  134  and the backflushing discharge valve  160  and reopening of the coarse dirt valve  150 , whereupon a new filtering phase of the backflushing filter  108  begins. 
     The backflushing phase of the backflushing filter  108  can be initiated if a predetermined maximum filling level of the coarse dirt in the coarse dirt line  152  is detected by means of the metal sensor  158  on the coarse dirt line  152 . 
     As an alternative or additionally to this, a backflushing phase of the backflushing filter  108  can be initiated if the differential pressure between the dirt side and the clean side of the filter element  128  exceeds a predetermined maximum value. 
     The processing of the fluid backflushed in the backflushing phase takes place in the sedimentation container  140  shown in  FIG. 4 to 7 . 
     As can be seen from  FIG. 4 , the fluid inlet  138  is oriented substantially tangentially to the inner wall of the container housing  164 , so that the backflushed fluid enters the interior of the sedimentation container  140  in a helical path  216 . 
     The solids contained in the backflushed fluid (coarse dirt and contaminants backflushed from the filter element  128 ) are sedimented in the sedimentation container  140  and arrive through the opened upper sluice valve  174  into the sluice chamber  178 , which is closed at the bottom by the closed lower sluice valve  176 . 
     A sediment collection  218  forms in the sluice chamber  178 . 
     Thus, the sedimentation container  140  and the sluice mechanism  172  together form a sedimentation device of the filter device  100 . 
     During this sedimentation phase shown in  FIG. 4 , the check valve  198  in the clear phase return line  196 , the compressed air valve  204  in the compressed air supply line  202  and the ventilation valve  210  in the ventilation line  208  are closed. 
     The fluid level  170  in the sedimentation container  140  rises during this sedimentation phase owing to the supply of backflushed fluid from the flushing line  136 . 
     After a predetermined sedimentation time has expired, the upper sluice valve  174  is closed. 
     The interior of the sedimentation container  140  is then acted upon in a controlled manner by compressed air with an excess pressure of, for example, about 0.3 bar, by opening the compressed air valve  204 . 
     Furthermore, the check valve  198  is opened in the clear phase return line  196 , so that the solids-free fluid (clear phase) contained in the interior of the sedimentation container  140  is forced through the screen  192  at the lower end of the flushing tube  188  into the clear phase return line  196  and returned by means of the clear phase return line  196  into the dirt tank  102 . 
     In the process, the clear phase level also rises in the air cushion chamber  220 , which is bounded outwardly by the flushing tube  188  and inwardly by the starting portion  194  of the clear phase return line  196 , so the air cushion  222  filling the upper region of the air cushion chamber  220  is compressed until the excess pressure of, for example, about 0.3 bar is reached, at which the compressed air is supplied to the interior of the sedimentation container  140 . 
     During this clear phase discharge phase, the beginning of which is shown in  FIG. 5  and the end of which is shown in  FIG. 6 , the fluid level  170  drops in the sedimentation container  140  until the predetermined minimum level shown in  FIG. 6  is reached, which is detected by means of the level probe  212 . 
     During this clear phase discharge phase, the sluice chamber  178  is emptied by opening the lower sluice valve  176 , so that the sediment which has accumulated in the sluice chamber  178  and which contains a solids fraction and residual fluid, arrives through the sedimentation discharge line  180  into the solids separator  182 . 
     After emptying the sluice chamber  178 , the lower sluice valve  176  is closed again (see  FIG. 6 ). 
     The solids fraction of the sediment is separated from the residual fluid in the solids separator  182 . The residual fluid is supplied to the dirt tank  102  by means of the residual fluid return line  186 . The solids content is supplied to the solids collection container  187  and supplied from there for further treatment or disposal. 
     On reaching the minimum fluid level  170  in the sedimentation container  140 , the compressed air valve  204  in the compressed air supply line  202  and the check valve  198  in the clear phase return line  196  are closed. 
     The ventilation valve  210  and the upper sluice valve  174  are then opened simultaneously, so the fluid column in the lower region of the air cushion chamber  220  is abruptly relieved of pressure. 
     The compressed air cushion  222  present in the upper region of the air cushion chamber  220  therefore abruptly expands downward, so the fluid located in the lower region of the flushing tube  188  is forced through the screen  192  into the lower portion  168  of the container housing  164  and in the process detaches contaminants which have accumulated on the screen  192  from the screen  192  and entrains them. 
     The contaminants thus detached from the screen  192  drop down through the opened upper sluice valve  174  into the sluice chamber  178 . 
     This concludes the screen cleaning phase shown in  FIG. 7 . 
     A renewed sedimentation phase of the sedimentation container  140  begins with the next opening of the backflushing discharge valve  160  (see  FIG. 4 ), i.e. with the next backflushing phase of the backflushing filter  108 . 
     In an alternative configuration of the above-described filter device  100 , the clear phase return line  196  does not lead from the sedimentation container  140  to the dirt tank  102  but to the clean tank  148 . 
     Otherwise, this alternative embodiment of the filter device  100  coincides with regard to structure and function with the above-described filter device  100 .