Abstract:
A filtering device includes multiple filtering elements ( 3 ) with bodies defining longitudinal axes. The filtering elements ( 3 ) are arranged adjacent to one another in a housing such that the longitudinal axes extend parallel to one another. The bodies of at least some of the filtering elements ( 3 ) have a shape that deviates from a circular cylinder at at least one part of the body length. The filtering elements ( 3 ) with bodies having a shape deviating from a circular cylinder have a cross-sectional size at least partially changing from one end to the other end. The filtering elements are oriented in the housing such that the regions of a larger cross-section are associated with the regions of a smaller cross-section in adjacent filtering elements.

Description:
FIELD OF THE INVENTION 
     The invention relates to a filtering device comprising a plurality of filtering elements with bodies defining longitudinal axes and arranged adjacent to one another in a housing such that the longitudinal axes of the filtering elements extend parallel to one another. The bodies of at least some of the filtering elements have a shape that deviates from a circular cylinder in at least one part of the body length. The invention further relates to a filtering element that is provided for use in such filtering device. 
     BACKGROUND OF THE INVENTION 
     Filtering devices of this kind are often used in technical facilities for filtering process liquids and pressure liquids such as hydraulic oils, coolant lubricants, and for treating liquid media and the like. Facilities that use such filtering devices can often only provide a limited amount of usable space for incorporating or attaching the filtering device. However, to be able to filter correspondingly large volume flows, the filtering surface that is provided by the filtering device must be sufficiently large. Wth regard to this requirement, a known filtering device of this kind is disclosed, for example, in DE 10 2004 026 862 A1. That device provides for filtering elements having bodies that deviate from the cross-section of a circular cylinder form, having the form of a Reuleaux triangle instead. In comparison to devices having circular cylindrical or block-shaped filtering elements, the shape of the Reuleaux triangle accommodates a larger filtering area inside a given installation space. 
     SUMMARY OF THE INVENTION 
     An object of the present invention to provide a filtering device that allows for a further improvement of the ratio between the installation space and the achievable filtering area. 
     According to the invention, this object is basically achieved with a filtering device including the filtering elements with cross-sections deviating from the cross-section of the circular cylinder shape and with cross-sections having sizes that change, at least in part, from one end to the other end. The filtering elements are oriented inside the housing such that the filtering elements adjacently disposed relative to each other have areas with larger cross-sections paired with areas having smaller cross-sections. Correspondingly, in a group of filtering elements containing filtering elements that are disposed next to each other and paired with each other and thereby forming a single group, more slender areas are disposed across from the thicker areas of the adjacently disposed partner element. Any free spaces or unused “dead space” within the group can then be minimized, achieving a correspondingly high packing density with an optimally large filtering area. 
     Especially advantageously, filtering elements in form of tapered candle filters are used, which are disposed adjacent to each other. The tapering of those candle filters are oriented in opposite directions, respectively. In this case, the filtering elements that are arranged into a group of adjacently disposed filtering elements delimit funnel-type fluid spaces inside the filter housing. Obvious combinations of convex external geometries with concave structures are also possible. This way, for example, layer-cake-shaped filtering elements can be combined with each other by providing that one convex layer-cake-shaped ring, in each case, engages in a concave recess between two adjacently disposed convex layer-cake-shaped rings of the other filtering element, preferably while maintaining a radial spacing. Aside from such stepwise ring arrangement, continually changing structures are conceivable as well, which provide for a barrel-like filtering element having a central, convexly protruding barrel part that engages, leaving a spacing, in a concave recess of an adjacent filtering element having a hose-shaped configuration, such that a rotational hyperboloid is formed. The abovementioned spacings between individual filtering elements are necessary for any sensible routing of the fluids inside the filter housing. All of the filtering elements constituted in this manner are preferably configured as rotationally symmetrical. 
     In especially advantageous embodiments, the filtering elements are tapered candle filters disposed inside the filter housing between a planar base plate and a cover plate that is disposed in a parallel plane in relation to the base plate. The corresponding result is a pot-shaped filter housing that receives the filtering elements by mounts on the base plate. An axial spacing exists between the ends of the filtering elements and the top cover plate. 
     Especially advantageously, the base plate can be configured as a connection plate and provided with fluid openings that can be used to bring fluid passages in fluid communication with the inner filtering cavities of the filtering elements. The elements are held by their ends on the base plate. 
     With candle filters having a tube-like support structure and a filtering medium surrounding the inside filtering cavity, especially advantageously, the ends of the tube-like support structure, allocated to the base plate, can constitute the fluid passages and engage with the fluid openings of the base plate, when each filtering element is in the functional position thereof. 
     On a base plate that serves as a connection plate, a closure piece can be located at the ends of the tube-shaped support structure on the filter candles, where the inner filtering cavities are allocated to the cover plate. The closure piece seals each filtering cavity in a fluid-proof manner. 
     Regarding the connection of the candle filters that are directed toward the base plate by the slender ends thereof, advantageously the tube-shaped support structure is extended by a connection tube, which engages in the related fluid opening and is axially secured on the base plate. 
     If candle filters are provided that include an external tube-shaped support structure, the support structure can form a radially protruding annular edge on the thicker end thereof. For candle filters having the thick end thereof oriented toward the base plate, this edge can be a contact area on the base plate. 
     On the more slender end, the internal support structure can form a cylinder part, which passes through a hollow cylindrical collar on the slender end of the external support structure. The collar is axially secured on the cylinder part. After disengaging this secured connection, the external support structure of the candle filter can be pulled off, for example, to replace the filter medium. 
     Especially advantageously, the collar can include a step constituting a shoulder, which is disposed in the radial plane. The annular edge of the external support structure of the respectively adjacent candle filter grips there-across. The annular edge of the external support structure thus constitutes a stop element for axially securing the candle filters inside the group. 
     To support the candle filters on the cover plate, spacers can be provided, respectively, on the collar of the external support structure and on the closed thicker end of the internal support structure. Preferably, they are formed thereto in one piece. 
     Another subject-matter of the present invention is a filtering element that is provided for use in the context of a filtering device according to the invention. 
     However, groups of filtering elements having varying cross-sections that are combined with such filtering elements having identical cross-sections inside the same filter housing, for example in the customary cylindrical design, also fall within the scope of the present invention. 
     Other objects, advantages and salient features of the present invention will become apparent from the following detailed description, which, taken in conjunction with the annexed drawings, discloses a preferred embodiment of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Referring to the drawings that form a part of this disclosure: 
         FIG. 1  is a schematically simplified, functional perspective view of a part of the base plate of the filter housing and a partial group of the filtering elements disposed on the base plate of a filtering device according to an exemplary embodiment of the invention; 
         FIG. 2  is a schematically simplified, side view in section of only a partial group of tapered candle filters on a partial section of the base plate of  FIG. 1 ; 
         FIG. 3  is a perspective view of only the external support structure of a candle filter for use in the filtering device of  FIG. 1 ; 
         FIG. 4  is an enlarged, partial perspective view of only the more slender end of the external support structure of  FIG. 3 ; 
         FIG. 5  is an enlarged, partial side view in section of only part of the filter candles on the base plate of  FIG. 2 ; 
         FIG. 6  is an enlarged, partial side view in section of only the partial area of  FIG. 2  that borders on the cover plate, which is not shown; and 
         FIG. 7  is an enlarged, partial perspective view of only the partial area of the group of candle filters from the group shown in  FIG. 1  that borders on the cover plate. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  only depicts a partial section of the base plate  1 , which is part of the embodiment of the filtering device according to the invention that shall be presently described and that is part of a filter housing, which is not shown in further detail. Base plate  1  accommodates a plurality of filtering elements formed as tapered candle filters  3  (in  FIG. 1 , not all of the candle filters are identified by reference numerals). As shown in  FIG. 1 , the candle filters  3  are grouped as densely packed, wherein the order thereof as provided is as follows. 
     In one given row, the candle filters  3  are oriented with the more slender or small ends thereof towards the base plate  1  and, in the respectively given adjacent row, the candle filters  3  are oriented with the thicker or large ends thereof toward the base plate  1 . The sequential rows of candle filters  3  are offset in relation to one another, respectively following such an arrangement in that the candle filters  3  that are in consecutive rows are disposed inside the gaps left by the respectively previous row. 
     Only a partial group of the total number of candle filters  3  is depicted in  FIG. 1 . The side wall, constituting a hollow cylinder, and the cover plate disposed in a parallel plane opposite in relation to the base plate  1  have also been omitted. During the filtration process, the internal space of the filter housing that surrounds the candle filters  3  constitutes the untreated side  51  ( FIGS. 5 and 6 ). The untreated fluid that must be cleaned can be supplied to untreated side  51  via a fluid inlet. The base plate  1  is configured as a connection plate and includes a fluid opening  5  for each candle filter  3  (in  FIG. 1 , not all of the candle filters are identified by reference numerals). The candle filters  3  are held or clamped between the cover plate and the base plate  1  such that the fluid passages  7  and  9 , see  FIGS. 2 and 5 , which are disposed at the thicker or large end or the more slender end of the candle filters  3 , respectively, are in fluid communication with the openings  5  of the base plate  1 . These fluid passages  7 ,  9  constitute the outlet from of the respective internal filter cavity  11  of the candle filters  3 . The internal fluid cavity constitutes the clean side during the filtration process, such that the cleaned fluid flows out of the filter housing via the openings  5  of the base plate  1 . 
     In  FIGS. 2, 3 and 6 , the candle filters  3  each feature an identical tapering. The ends of the filter cavities  11 , however, are configured differently, depending on whether the candle filters  3  are disposed in fluid communication with the openings  5  by the more slender ends thereof or by the thicker ends thereof. More precisely, the filter cavity  11 , which is open at the bottom end due to the passages  7  and  9 , and connected by the openings  5  of the base plate  1 , is closed at the opposite end that is depicted as the top end in the drawing. Regarding tapered candle filters, it is known in the art that a tube-like internal support structure  13  defines the internal filter cavity  11 . As most clearly visible in  FIG. 6 , on the candle filters  3  that are closed at the more slender or small top ends thereof, a cylinder part  15 , which is formed in one piece to the end of the support structure  13 , constitutes the closure of the filter cavity  11 . However, on each thicker, closed top end, an end part  19  of the internal support structure  13 , with screwed-in closure plug  17  configured as having a closed wall part, constitutes the closure piece of the internal filter cavity  11 . 
     A filter mat  21 , disposed on the outside of the internal support structure  13  can be provided, for example, as a non-woven filtration material, such as a non-woven polyester or the like, which is placed around the support structure  13 . Alternatively, a fiber application can be directly applied to the support structure  13  by a melt-blown process. The type and specification of the respective filter medium  21  will depend on the purpose of use and the operating conditions of the filtering device. 
     At the end that is oriented toward the base plate  1 , the internal support structure  13  forms, together with the closed end part  19 , a connection piece  23  for the engagement in the corresponding opening  5  of the base plate  1 . The candle filters  3  that are oriented with the more slender ends thereof toward the base plate  1  include, instead of the cylinder part  15  serving as closure piece, a connection tube  25  formed in one piece with the internal support structure  13  and passing through the related opening  5 . The tube  25 , and thereby the candle filter  3 , is axially secured inside the opening  5 . In the present example, a bayonet catch  27  is provided for this purpose. Alternately, providing a clip for securing the screwed connection is also possible. 
     In the present example, the candle filters  3  include an external, tube-like support structure  29  that surrounds the outer side of the filter medium  21 , which is shown separately in  FIG. 3 . The outer support structure  29  is a grate-shaped structure, like the internal support structure  13 , preferably press-formed in one piece of a plastic material. Structure  29  can accommodate a through-flow of fluid through the openings that are provided by the grate structure. At the thicker end, the support structure  29  forms a radially protruding annular edge  31 , which rests against the base plate  1  in the installed state. Formed in one piece with the opposite, closed end of the support structure  29  is a removal part  33 , showing a removal ring  35  for manually extracting the filtering element from the filter housing. The outer support structure  29  is connected to the cylinder part  15  by a bayonet attachment  37 , which is hinted at only in  FIG. 4 . After releasing the bayonet  37 , the external support structure  29  can be drawn off and removed. Corresponding to the removal part  33  of the respectively closed ends of the candle filters  3 , the removal parts  39 , which are disposed on the thicker, closed ends, are provided with the removal rings  41 , corresponding to the removal rings  35  on the more slender ends. 
     The annular edges  31  on the external support structure  29  form a kind of toothing with the more slender ends of the external support structure  29  of adjacent candle filters to provide mutual, axial cohesion of the group of the candle filters  3 . More precisely, as shown particularly in  FIG. 6 , the external support structures  29  include on the ends thereof a collar  43  that forms a type of a hollow cylinder. The cylinder part  15  of the internal support structure  13  passes there-through. The collar  43  constitutes a circumferential step  45  that forms a shoulder area  47 , which is disposed in the radial plane, and that reaches over the annular edge  31  of the thicker end of the external support structure  29  of the respectively adjacent candle filter  3 , as demonstrated particularly in  FIGS. 5 and 6 . 
     With the group of candle filters  3  cohesively held together in this manner by the base plate  1 , the untreated side  51  is sealed off from the clean side that is located inside the filter cavity  11 , by sealing edges  53  that are formed, as hinted at in  FIG. 5 , on the collar  43  of the internal support structure  13 . Furthermore, there exists the option of backwashing the candle filters  3  by reversing the fluid flow from the clean side  11  in the direction of the untreated side  51 . 
     In the preceding, the tapered candle filters  3  were described as comprising multiple structural parts with support structures  13 ,  29  and filter medium  21  disposed there-between. However, the candle filters can be envisioned as tapered slotted screen tube elements that would be disposed in corresponding groups having a reversed tapering in relation to each other. 
     While one embodiment has been chosen to illustrate the invention, it will be understood by those skilled in the art that various changes and modifications can be made therein without departing from the scope of the invention as defined in the claims.