Abstract:
A filter device includes in a filter housing a hollow cylindrical filter element having frontal end plates, a flow opening being made in one of the end plates. In order to interlockingly secure a pipe connection piece that communicates with the flow opening, a cover has a radial collar which forms an axial stop for the pipe connection piece.

Description:
TECHNICAL FIELD 
       [0001]    The invention relates to a filter device, especially a fluid filter, according to the preamble to claim  1 . 
       BACKGROUND 
       [0002]    EP 2 110 539 A2 describes a filter device for diesel fuel, which device has a ring-shaped filter element in a pot-shaped filter housing, the fuel to be filtered flowing through the filter element radially from the outside to the inside. The filter element has an end disc on each of its axial end faces. The unfiltered fuel is supplied in the region of a first axial end face via a heating module that is flange-mounted to a cover of the filter housing and is retained using a connector. Inserted in the heating module is a feed pipe for connecting to a fuel line, the fuel being conducted on the opposing side of the heating module via another pipe to the radially outwardly disposed unfiltered side of the filter element. A central fitting on the heating module projects into the clean area through an opening in the end disk; the central fitting is part of a pressure gauge device via which it is possible to measure the differential pressure between the unfiltered side and the filtered side. The filtered fluid is conducted away via the end disk of the filter element axially opposing the heating module. 
       SUMMARY 
       [0003]    The underlying object of the invention is to join a pipe connecting piece to a filter device in a structurally simple manner. 
         [0004]    The inventive filter device or cartridge is preferably used for filtering fluids, especially for filtering fuel such as, for instance, diesel fuel. In principle, however, it may also be used for filtering gaseous fluids. 
         [0005]    In a filter housing the filter device has a hollow cylindrical or annular filter element through which the fluid to be filtered flows radially from the outside to the inside. At each of its two axial end faces the filter element has an end disk, a flow opening into which a pipe connecting piece may be inserted being added to at least one end disk. When the flow direction is radially from outside to inside, the interior forms the filtered side via which the filtered fluid may be conducted away axially via the flow opening and the pipe connector part. 
         [0006]    The filter housing also has a cover that closes the open side of the filter housing with the filter element accommodated therein. The pipe connecting piece is attached to the cover in a positive fit. For this, the cover or a component joined to the cover has a radially oriented collar—relative to the longitudinal filter axis—that, when mounted, forms an axial stop for the pipe connecting piece. This positive fit securing and retention of the pipe connecting piece on the cover represents an easy-to-assemble, easy-to-produce connection that can be released easily so that if necessary the filter device may be exchanged and a new filter device may be connected to the existing pipe connecting piece. The positive fit is axial, and the pipe connecting piece is mounted axially on the filter device. 
         [0007]    In one preferred embodiment, cover and filter housing are permanently joined to one another, for instance by welding, soldering, beading, or gluing. Thus a disposable filter that is simple to exchange is embodied that may in particular be connected to a filter head or an inventive pipe connecting piece. 
         [0008]    Embodiments having a radially inwardly oriented and a radially outwardly oriented collar on the cover may both be considered. What is essential is that a dedicated connection segment axially engages the collar at the pipe connecting piece. For assembly, pipe connecting piece and filter device are moved axially towards one another until the connection segment axially engages the collar in the desired manner, whereupon the positive fit is produced using a radial adjusting motion between pipe connecting piece and filter device, that is, transverse to the longitudinal filter axis. 
         [0009]    According to a preferred embodiment, however, it is also possible to produce the positive fit between pipe connecting piece and collar on the cover of the filter device using a latch that may be inserted into a positive fit pocket on the connection segment, which positive fit pocket is arranged between the radially oriented collar and the connection segment on the pipe connecting piece. The insertion direction for the latch is especially transverse to the longitudinal filter axis, that is, radial, as well. The latch in the positive fit pocket is disposed axially between the collar and a component on the connection segment of the pipe connecting piece and prevents axial removal between pipe connecting piece and filter device, so that the pipe connecting piece is secured to the filter device in a positive fit. 
         [0010]    The latch is embodied, for instance, in a U shape and is inserted radially into its locking position through a recess in the wall of the connection segment delimiting the positive fit pocket, in which position axial detachment of the pipe connecting piece from the cover is prevented. However, also possible is a rectangular embodiment of the latch, which is also inserted radially into a recess in the wall of the positive fit pocket and projects into the positive fit pocket. 
         [0011]    The collar is either embodied integrally with the cover or separately therefrom, but is preferably joined to the cover such that it cannot be lost or detached, for instance by welding, soldering, beading, or gluing. The cover comprises metal, for instance; the collar may also be embodied as metal component. In a different embodiment, the collar is joined to the cover using beading, for instance, or is soldered to the cover. When cover and collar are embodied integrally, latter is produced by master forming or radially bending an axial segment of the cover. 
         [0012]    According to another useful embodiment, especially radially offset to the positive fit pocket the filter device has a sealing pocket that receives a sealing element on the cover. The sealing pocket is axially delimited by the collar or a cover segment and hereby axially secures the inserted sealing element in a positive fit. The sealing element may be embodied as a sealing ring that is retained on the cover, for instance that is placed onto a fitting on the cover. The sealing element separates the unfiltered side from the filtered side of the filter element. 
         [0013]    According to another useful embodiment, the collar is spaced apart from the cover on the outside of the latter. This may be realized in that provided on the cover is a pipe-shaped, especially flow-guiding, projection, and on its end spaced apart from the cover the collar is arranged. Spaced apart from the cover shall be construed to mean that the cover has a cover surface that closes the housing and from which the collar, which may certainly also be a part of the cover, is spaced. Due to this, further preferably an especially radially outwardly open annular engagement area for a latch may be formed between cover and collar, wherein particularly preferably the sealing pocket is arranged axially at a height between collar and cover and thus radially within the engagement area. Because of the arrangement of the seal in the immediate vicinity of the collar, at which the positive fit connection may occur, changes in the shape of the individual parts in the area of the seal, which changes are caused by vibrations, are so small that the risk of vibration-induced leaks is reduced. 
         [0014]    The sealing pocket for receiving the sealing element may be arranged offset radially inward opposing the positive fit pocket. With respect to the longitudinal filter axis, axially offset arrangements of sealing pocket and positive fit pocket and arrangements of sealing pocket and positive fit pocket at the same axial height are both possible. Where necessary, embodiments in which the sealing pocket is arranged offset radially outward to the positive fit pocket are also possible. 
         [0015]    The sealing pocket may be axially delimited using a delimiting part that, according to another advantageous embodiment, is embodied separately from the collar and is also arranged on the cover. In some aspects of the invention, integral embodiment of the delimiting part and the collar is provided. The delimiting part may comprise the same material as the collar and may be joined to the cover like the collar, for instance using soldering. Integral embodiment of the delimiting part and the cover is also possible. 
         [0016]    A centering element that receives the pipe connecting piece may be inserted into the end disk of the filter element. A sealing element is advantageously inserted between pipe connecting piece and centering element in order to provide a flow-tight connection between the centering element and the pipe connecting piece. 
         [0017]    According to another advantageous embodiment, the unfiltered fluid is supplied and the filtered fluid is conducted away via the same axial end face of the filter element or via the cover. Also possible are embodiments in which a pipe connecting piece has a common housing for a supply channel for supplying unfiltered fluid and a discharge channel for conducting the filtered fluid away. In one advantageous embodiment, supply channel and discharge channel are disposed coaxially in that one channel radially surrounds the other channel, the channels being separated from one another flow-tight in order to prevent an undesired exchange of unfiltered and filtered fluid. For instance, the radially interiorly disposed channel may form the discharge channel for conducting filtered fluid away and the surrounding channel having a larger diameter may be the supply channel for supplying the unfiltered fluid. 
         [0018]    However, a parallel offset arrangement of supply and discharge channel in a common housing of a pipe connecting piece may also be considered. Moreover, embodiments are possible in which two pipe connecting pieces are arranged disposed adjacent to one another on the cover, the pipe connecting pieces being embodied independently of one another. 
         [0019]    According to another advantageous embodiment, a non-return valve may be integrated in the pipe connecting piece. The non-return valve prevents undesired outflow of fluid that is still in the pipe connecting piece when the pipe connecting piece detaches from the filter device. If a non-return valve is also arranged in the supply channel, the non-return valve prevents uncontrolled discharge of unfiltered fluid when the pipe connecting piece detaches from the filter device. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]    Additional advantages and useful embodiments may be found in the other claims, the description of the figures, and the drawings. 
           [0021]      FIG. 1  depicts a fluid filter having an annular or hollow cylindrical filter element in a filter housing, on which a cover is placed and on which a pipe connecting piece is retained in a positive fit; 
           [0022]      FIG. 2  depicts an enlarged detail from the area of the positive fit attachment of the pipe connecting piece to the cover; 
           [0023]      FIG. 3  depicts cover and pipe connecting piece, detached; 
           [0024]      FIG. 4  depicts, in a variant, a connection between pipe connecting piece and cover; 
           [0025]      FIG. 5  depicts, in another variant, a pipe connecting piece in a positive fit connection with the cover; 
           [0026]      FIGS. 6, 7  depict other variants of pipe connecting piece and cover,  FIG. 7  illustrating an enlarged detail from  FIG. 6 ; 
           [0027]      FIG. 8  depicts another variant of pipe connecting piece and cover; 
           [0028]      FIG. 9  depicts a fluid filter with integrated pressure control valve in the pipe connecting piece; 
           [0029]      FIG. 10  depicts a fluid filter with integrated non-return valves in the pipe connecting piece, in which pipe connecting piece a supply channel and a discharge channel are arranged coaxially; 
           [0030]      FIG. 11  depicts a fluid filter with integrated air vent screw in the pipe connector part; and 
           [0031]      FIGS. 12 through 14  depict various views of a fluid filter having two separately embodied pipe connecting pieces for the supply and the discharge of the fluid. 
       
    
    
       [0032]    In the drawings, like components are assigned like reference signs. 
       DETAILED DESCRIPTION 
       [0033]    Each of the figures depicts a filter device  1  that is embodied as a fluid filter for filtering fuel, for instance diesel fuel. In the exemplary embodiment according to  FIGS. 1 through 3 , the filter device  1  has a pot-shaped filter housing  2  that is for receiving an annular or hollow cylindrical filter element  3  and through which the fluid to be filtered flows radially from the outside to the inside. The interior  4  in the filter element  3  consequently forms the filtered side, the radially outwardly disposed surface forms the unfiltered side on the filter element. The axial end faces of the filter element  3  are closed by end disks  5  and  6 . Adjacent to the upper end disk  5 , which has a central flow opening, a pipe connecting piece  7  having a supply channel  8  for supplying unfiltered fluid and a discharge channel  9  for conveying away filtered fluid may be attached to the filter device  1 . The pipe connecting piece  7  may be attached to a cover  10 , which is placed onto the open side of the pot-shaped filter housing  2 . The cover  10  is securely connected to the filter housing. 
         [0034]    The discharge channel  9  of the pipe connecting piece  7  projects into the central flow opening in the end disk  5  on the filter element  3  and communicates with the interior  4 , in which the filtered fluid collects. The filtered fluid is thus conveyed out of the interior  4  via the central flow opening in the end disk  5  and via the discharge channel  9  in the pipe connecting piece  7 . 
         [0035]    The pipe connecting piece  7  is embodied as a dual connector having a common housing for the supply channel  8  and the discharge channel  9 . Supply channel  8  and discharge channel  9  are arranged concentric to one another, wherein the supply channel  8  has a larger diameter than the discharge channel  9  and surrounds the latter. The channels  8 ,  9  are connected to tubes for supplying and conveying away the fluid via connecting elements  8   a  and  9   a.    
         [0036]    The unfiltered fluid is supplied via the connecting element  8   a  and the supply channel  8  to the radially outwardly disposed surface of the filter element  3 , through which fluid to be filtered flows radially from the outside to the inside. As described in the foregoing, the fluid is conveyed away from the interior  4  axially via the discharge channel  9  and the connecting element  9   a  and further via the connected tube. 
         [0037]    The pipe connecting piece  7  is embodied separately from the filter device  1  and is retained on the cover  10  in a positive fit. The positive fit is effected in the direction of the longitudinal filter axis  11  via a curved collar  12  ( FIGS. 2, 3 ), which is embodied separately from the cover  10  but is connected to the cover  10 . Added to the cover  10  is a central opening for receiving the pipe connecting piece  7 , wherein a radially inwardly curved delimiting segment  13  is molded on the wall delimiting the central opening on the cover  10  and bears the collar  12  that extends radially outward. The collar  12  may be attached by beading the delimiting segment  13  on cover  10 . 
         [0038]    A connecting segment  14  is embodied integrally with the housing of the pipe connecting piece  7  and houses a positive fit pocket  15 , the connecting segment  14  axially surrounding the radially outwardly oriented collar  12 . In order to produce an axially positive fit connection between the pipe connecting piece  7  and the cover  10 , a latch  16  is inserted into the positive fit pocket  15  in the connecting segment  14  and engages the radially outwardly oriented segment of the collar  12  according to  FIG. 2 . At the same time, the latch  16  is retained by the U shaped walls of the connecting segment  14 . The latch  16  is embodied, for instance, in a U shape and is inserted via transversely extending recesses in the wall of the connecting segment  14  until it reaches the axially positive fit position. Then the pipe connecting piece  7  is retained on the cover  10  axially in a positive fit. 
         [0039]    The radially inwardly oriented delimiting segment  13  on the cover  10  also delimits a sealing pocket  17  into which a sealing ring  18  retained on the cover  10  is inserted. In the opposing direction, the sealing ring  18  is axially supported by a centering element  19  that is arranged on the end disk  5  and into which the pipe connecting piece  7  may be inserted. The sealing pocket  17  is disposed axially at about the same height as the positive fit pocket  15 , but offset radially inwardly relative to the positive fit pocket  15 . 
         [0040]    Another sealing element  20  is disposed on the central flow opening that is added to the end disk  5 , the discharge channel  9  being positioned against the annular sealing element  20 . 
         [0041]    In  FIG. 4 , the axial positive fit connection between the pipe connecting piece  7  and the cover  10  is the same as in the first exemplary embodiment according to  FIGS. 1 through 3 . 
         [0042]    However, in  FIG. 4  the centering element  19 , which is embodied integrally with the end disk  5 , is embodied positioned directly against the outer wall of the discharge channel  9 , while in  FIGS. 1 through 3  the centering element is arranged spaced radially apart from the discharge channel  9 . The axial support of the sealing ring  18  in the sealing pocket is provided via a support element that is also advantageously embodied integrally with the end disk  5  or is arranged at the end disk. 
         [0043]    In the exemplary embodiment according to  FIG. 5 , the collar  12  is embodied integrally with the cover  10 . The collar  12  forms the radially outwardly curved end segment of the cover  10  in the area of the wall delimiting the central opening. 
         [0044]    Added to the housing of the pipe connecting piece  7 , in the area of the connecting segment  14 , is a transversely extending opening into which is inserted a rectangularly embodied latch  16  gripped by the collar  12 . This results in an axial positive fit connection between the pipe connecting piece  7  and the cover  10 . 
         [0045]    The axially extending wall of the cover  10 , which wall delimits the central opening, forms a support for the sealing ring  18  radially outward. 
         [0046]    In the exemplary embodiment according to  FIGS. 6 and 7 , the collar  12  is embodied separately from the cover  10  and is joined to the cover  10  in a suitable manner, for instance by soldering. On its end facing the cover  10 , the collar  12  has a radially outwardly curved segment that, when mounted, engages the transversely inserted rectangular latch  16 . 
         [0047]    The sealing pocket  17  for receiving the sealing ring  18  is engaged by a delimiting part  21  that is embodied integrally with the cover and forms the radially inwardly curved end segment in the area of the central opening in the cover. The delimiting part  21  is disposed offset radially inwardly relative to the collar  12 . The sealing ring  18  is delimited radially outwardly by a wall  22  that is embodied integrally with the connecting segment  14  on the pipe connecting piece  7 . 
         [0048]    In the exemplary embodiment according to  FIG. 8 , the collar  12  is oriented radially outward and is embodied integrally with a positive fit component  23  that is embodied separately from the cover  10 , but is securely connected thereto. The positive fit component  23  with the radially outwardly oriented collar  12  for securing the inserted latch  16  and the connecting segment  14  in a positive fit delimits, radially inwardly, a sealing pocket for receiving the sealing ring  18 . 
         [0049]    In the exemplary embodiment according to  FIG. 9 , the positive fit connection between the pipe connecting piece  7  and the cover  10  is embodied as in the first exemplary embodiment according to  FIGS. 1 through 3 . The pipe connecting piece  7  is also embodied as described in the foregoing as a dual connector with integrated supply channel  8  and discharge channel  9 . In addition, the pipe connecting piece  7  is fitted with a pressure control valve  24  that keeps the system fuel pressure upstream of the injection valves at a constant value relative to the intake pressure (fuel differential pressure). Because of this, the injection quantity is dependent only on the actuation period for the injection valves and is reproducible under all operating conditions for the actuation period. Consequently the same quantity of fuel is injected per unit of time at all pressures. 
         [0050]    The pressure control valve  24  is a bypass valve that releases, via a spring-loaded diaphragm, a return channel  26  for the fuel for refuelling when the set pressure is exceeded. The pressure control valve  24  has a negative pressure line to the intake (intake connector  25 ) so that the absolute fuel pressure may be altered proportionate to the intake pressure. 
         [0051]    In the exemplary embodiment according to  FIG. 10 , non-return valves  27  and  28  are integrated in the supply channel  8  and discharge channel  9 . The non-return valve  27  in the supply channel  8  is disposed in the area of the connecting element  8   a , while the non-return valve  28  in the supply channel  9  is positioned directly at the end projecting into the interior of the filter element  3 . The non-return valves  27 ,  28  open in the direction of the regular flow direction of the supply or discharge of unfiltered or filtered fluid and close in the opposing direction. 
         [0052]    In the exemplary embodiment according to  FIG. 11 , the pipe connecting piece  7  is fitted with an air vent screw  29  that is arranged in the area of the discharge channel  9 . 
         [0053]    In the exemplary embodiment according to  FIGS. 12 through 14 , two separately embodied pipe connecting pieces  7   a  and  7   b  are provided that are both retained on the cover  10  in a positive fit. The first pipe connecting piece  7   a  has the supply channel  8 , the second pipe connecting piece  7   b  has the discharge channel  9 . 
         [0054]    The pipe connector pieces  7   a  and  7   b  are arranged parallel to one another and are both retained on the cover  10  in the same manner in a positive fit. The pipe connecting piece  7   b  with the discharge channel  9  is arranged centrically, the pipe connecting piece  7   a  with the supply channel  8  is parallel and offset thereto. Two offset recesses, each for receiving a pipe connecting piece  7   a  or  7   b , are correspondingly arranged offset in the cover  10 . 
         [0055]    The positive fit connection is effected in each case using the connecting segment  14  on the pipe connecting piece, to which a lateral opening is added for inserting the rectangular latch  16 . When inserted, the latch  16  engages with the collar  12  ( FIGS. 13, 14 ), which is embodied separately from the cover  10  but is joined to the cover  10  using beading.