Abstract:
A liquid filter having a housing with a removable cover and an exchangeable cylindrical insert enclosed by two end disks. The filter has a bypass valve and the upper end disk has a central valve seat interacting with a valve body. The housing has a central discharge duct, with a closure pin fixed in the duct which is axially adjustable between closed and open positions. The filter has a valve body carrier connected, with limited axial displaceability, to the pin. The carrier, on its free end, has the bypass valve body, and onto which the insert end disk is mountable. The carrier is preloaded with a force, acting in the closing direction of the valve via a housing spring. During mounting of the insert onto the carrier, a force acting in the closing direction of the closure pin can be exerted directly on the pin by the insert.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of the German patent application No. 102012210834.3 filed on Jun. 26, 2012, the entire disclosures of which are incorporated herein by way of reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    The present invention relates to a liquid filter, in particular an oil filter of an internal combustion engine, having a filter housing having a removable cover and having a raw liquid inlet and a clean liquid outlet, having a filter insert that is situated exchangeably in the filter housing and that separates a raw side and a clean side of the liquid filter from one another, the insert having a hollow cylindrical filter material body enclosed at its end faces by two end disks, the end disk that is the lower end disk in the installed state having a central mounting opening, the liquid filter having a filter bypass valve, for which purpose the end disk that is the upper end disk in the installed state having on its lower side a central valve seat that works together with a valve body, the filter housing further having a central discharge duct for emptying the filter housing when the filter insert is removed, and there being situated in the discharge duct a closing pin that is fixed to the housing in the installed state and that can be axially displaced between a closed position, assumed when the filter insert is installed and the cover is closed, and an open position, assumed when the cover is removed and the filter insert is removed. Moreover, the present invention relates to a filter insert for a liquid filter. 
         [0003]    A liquid filter of the type indicated above is known from DE 201 18 683 U1. In this known liquid filter, the closing pin extends from the discharge duct upward into the filter insert, up to the upper end disk thereof. At the upper end of the closing pin, there is situated a valve body of the filter bypass valve, this valve body being axially displaceable relative to the closing pin, and the valve body being loaded with a force that acts upward, i.e., in the closing direction of the filter bypass valve, by a spring supported on the closing pin. Between the filter housing and a lower part of the closing pin there is situated a further spring that loads the closing pin with a force acting upward, i.e., in the direction toward the cover of the filter housing. 
         [0004]    In this existing art, it is regarded as disadvantageous that a relatively large number of components, in particular two different springs, are required, resulting in correspondingly high production and assembly costs. Moreover, in this known liquid filter, the use of foreign filter inserts cannot effectively be prevented. 
       SUMMARY OF THE INVENTION 
       [0005]    Therefore, for the present invention an object arises of creating a liquid filter of the type named above that avoids the indicated disadvantages and that in particular requires a lower number of individual parts, and in this way can be produced and assembled at lower cost. Moreover, a fitting, specific filter insert is to be created for the liquid filter according to the present invention. 
         [0006]    According to the present invention, the first part of this object, relating to the liquid filter, is achieved by a liquid filter of the type described above that is characterized in that:
       connected to the closing pin, so as to be capable of axially limited displacement, there is a valve body carrier that runs through the filter insert and that has a valve body of the filter bypass valve on its free end, and onto which the filter insert can be mounted with its end disk having the mounting opening forward,   the valve body carrier is pre-loaded with a force, acting in the closing direction of the filter bypass valve, of a spring supported on the filter housing, and   the filter insert can exert, during or during and after its mounting onto the valve body carrier, a force acting immediately on the closing pin in the direction toward the closing position of the closing pin.       
 
         [0010]    The present invention advantageously brings it about that the desired functioning of the filter bypass valve and discharge duct can be realized using only a single spring, without having to accept an impairment of the functioning or operational reliability of the liquid filter. In this way, the outlay in the production of the individual parts and in the assembly of the liquid filter, and thus the overall costs thereof, are reduced. At the same time, the liquid filter according to the present invention is robust and not sensitive to the danger of damage that can occur during possibly incorrect maintenance, because the closing pin is well protected inside the discharge duct, and only the valve body carrier connected to the closing pin runs through the filter insert. 
         [0011]    In order to further promote low-cost production and assembly and good durability, it is preferably provided that the valve body carrier and the valve body of the filter bypass valve are fashioned in one piece. 
         [0012]    In order to achieve a compact construction and a high degree of functional reliability, it is further preferably provided that the closing pin has, in its upper end region, two or more pusher lugs that are distributed around the circumference and that protrude radially outward past the outer circumference of the valve body carrier, on which lugs the thrust force acting in the direction toward the closing position of the closing pin can be exerted by the filter insert. 
         [0013]    Usefully, the closing pin and the valve body carrier are held so as to be not capable of rotation relative to one another, which is advantageous for a precise mutual axial guiding. 
         [0014]    In a preferred development of the liquid filter, it is proposed that actuating elements for the pusher lugs are situated on the lower end disk or on a supporting lattice of the filter insert. Here, the actuating elements can be simply integrally formed on, stably constructed, and housed in a space-saving fashion. 
         [0015]    Preferably, here it is provided that the actuating elements are formed by two or more ribs that run axially and that protrude radially inward, or by a toothed configuration having a plurality of axially running teeth that protrude radially inward. In this way, a design is achieved that is stable and not liable to damage, and a spatially advantageous housing is also achieved. 
         [0016]    In addition, it is provided that cooperating positioning guide means are situated on the inner circumference of the filter insert and on the outer circumference of the valve body carrier, with which the filter insert can be force-guided into a correctly engaged position of its actuating elements relative to the pusher lugs when the filter insert is mounted onto the valve body carrier in the circumferential direction. In this embodiment, a particularly reliable functioning is ensured. Moreover, in this way a key-lock system can be realized that prevents the insertion of foreign filter inserts that do not fit and that do not have the positioning guide means and actuating elements. 
         [0017]    In order to achieve a simple construction, preferably the actuating elements for the pusher lugs are identical to the positioning guide means provided on the filter insert. 
         [0018]    In order to achieve a compact configuration of the individual parts, a helical pressure spring, surrounding the closing pin, is usefully situated as a spring between the lower end of the valve body carrier and the filter housing. 
         [0019]    In order to facilitate the installation of the spring in the discharge duct of the liquid filter, the present invention proposes that on the outer circumference of the valve body carrier there are provided a plurality of outward-oriented retaining cams that engage with the spring when the spring is relaxed and are disengaged from the spring when the spring is at least partially compressed. Because in the installed state the spring is always more or less compressed, in this state it has no engagement with the valve body carrier, and therefore in the installed state does not exert any immediate force on the valve body carrier. 
         [0020]    In order to ensure a mounting of the valve body carrier in the filter housing that is secure and not sensitive to damage or loss, it is proposed that the valve body carrier is guided in the filter housing, with a lower segment, so as to be capable of axial displacement, and that the displacement path of the valve body carrier is limited in the direction of excursion relative to the filter housing by a flexible cam system. 
         [0021]    So that the sensor does not have to be immediately grasped during a filter maintenance session involving a change of the contaminated filter insert, it is proposed that the cover has on its lower side, and the upper end disk of the filter insert has on its upper side, cooperating releasable first locking connection means, rotatable relative to one another, with which a specifiable first tensile force in the axial direction can be transmitted. In this way, when the cover is removed from the filter housing the filter insert locked to the cover is removed from the filter housing along with it. 
         [0022]    In addition, it is provided that the filter insert on the one hand, and the valve body carrier or the closing pin on the other hand, have cooperating releasable second locking connection means with which a specifiable second tensile force, smaller than the first tensile force, can be transmitted in the axial direction. These second locking connection means act, before a first installation of the liquid filter, to hold the valve body carrier and the closing pin on the filter insert so as to be adequately secured against unintentional loss, without hindering the later removal of the filter insert together with the cover secured thereto during the filter maintenance described in the previous paragraph. 
         [0023]    In order to achieve a reliable sealing effect at low cost, preferably a, or each, seal provided on the closing pin is a radially sealing seal, preferably a sealing ring, more preferably an O-ring. Such seals are standardly available commercially at low cost, in a large number of different embodiments. 
         [0024]    The liquid filter according to the present invention can be realized as an individual component, and can be connected to the engine block of an internal combustion engine, for example as an oil filter. For this embodiment as an individual component, it is preferably provided that the closing pin has a radially sealing seal in its lower part cooperating with the discharge duct, and that the discharge duct has, in its region that cooperates with the seal during the axial movement of the closing pin, two segments having different inner diameters becoming larger in stepped fashion going from below to above, the seal being situated freely in the segment having the larger inner diameter in the opening position, and being situated in sealing fashion in the segment having the smaller inner diameter in the closing position of the closing pin. 
         [0025]    Alternatively, the liquid filter according to the present invention can also be part of a functional module having a plurality of components. Here, the present invention proposes that the liquid filter is connected to, or can be connected to, a heat exchanger for the liquid flowing through the liquid filter, and that the closing pin has, in its lower part cooperating with the discharge duct, two radially sealing seals axially at a distance from one another, and that the discharge duct has, in its region that cooperates with the seals during the axial movement of the closing pin, two segments having different inner diameters, becoming larger in stepped fashion from below to above, the seal having the smaller diameter being situated in sealing fashion in the segment having the smaller inner diameter in the closed position of the closing pin, and being situated in open fashion in the segment having the larger inner diameter in the open position of the closing pin, the seal having the larger diameter always being situated in sealing fashion in the segment having the larger inner diameter, and a first connecting channel between the liquid filter and the heat exchanger above the seal having the larger diameter going out from the discharge duct, and a second connecting channel between the heat exchanger and the liquid filter between the two seals opening into the discharge duct. In this way, it is achieved that during a filter maintenance both the filter housing and a heat exchanger connected thereto, in particular an oil cooler, is emptied of liquid, the path of the liquid flowing out from the filter housing running through the heat exchanger. 
         [0026]    An alternative embodiment proposes that the liquid filter is connected to, or can be connected to, a heat exchanger for the liquid flowing through the liquid filter, and that the closing pin has, in its lower part cooperating with the discharge duct, two radially sealing seals situated at an axial distance from one another having different diameters, and that the discharge duct has, in its region cooperating with the seals during the axial movement of the closing pin, three segments having different inner diameters, becoming larger going from below to above, the seal with the smaller diameter being situated in sealing fashion in the segment having the smallest inner diameter in the closing position of the closing pin, and being open in the segment having the middle inner diameter in the open position of the closing pin, the seal having the larger diameter being situated in sealing fashion in the segment having the middle inner diameter in the closing position of the closing pin and open in the segment having the largest inner diameter in the open position of the closing pin, and a first connecting channel between the liquid filter and the heat exchanger above the seal having the larger diameter going out from the discharge duct, and a second connecting channel between the heat exchanger and the liquid filter between the two seals opening into the discharge duct. In this embodiment of the liquid filter, during a filter maintenance the liquid can flow out from the filter housing in parallel through the heat exchanger and past this heat exchanger immediately through the discharge duct, which shortens the time required to empty the filter housing. 
         [0027]    Liquid filters are today in most cases completely or partly produced by suppliers and then supplied to customers who install the liquid filters, possibly after completion. Frequently, the customer supplies the filter housing and the supplier supplies all other parts of the liquid filter. In order to make the completion and subsequent installation of the liquid filter as easy as possible for the customer, according to the present invention it is provided that the liquid filter can be assembled from the filter housing on the one hand and a preassembled assembly on the other hand during its initial assembly, the preassembled assembly including the closing pin, the valve body carrier, the spring, the filter insert, and the cover. In this way, no loose individual parts have to be supplied and installed; the customer only has to introduce the preassembled assembly into the filter housing and connect the cover to the housing, standardly by screwing. After this, the liquid filter is immediately ready for use. 
         [0028]    In addition, the present invention relates to a filter insert for a liquid filter, in particular for an oil filter of an internal combustion engine, the filter insert being made up of a hollow cylindrical filter material body enclosed at its ends by two end disks, the end disk that is the lower end disk in the installed state having a central mounting opening for mounting the filter insert onto a central valve body carrier of the liquid filter. 
         [0029]    In order to achieve the second part of the object of the invention, relating to the filter insert, a filter insert is proposed that is characterized in that
       actuating elements are situated on the filter insert or are guided with the filter insert, by means of which the filter insert can exert a force immediately on pusher lugs of the closing pin, the force acting in the direction towards the closing position of a discharge duct closing pin of the liquid filter, and   there being situated on the inner circumference of the filter insert first positioning guide means that are fashioned to cooperate with second positioning guide means situated on the outer circumference of the valve body carrier, such that with the positioning guide means the filter insert can be force-guided into a position proper for engagement of its actuating elements relative to the pusher lugs in the circumferential direction when the filter insert is mounted onto the valve body carrier.       
 
         [0032]    The filter insert according to the present invention has specific elements that make it usable only for use in a liquid filter having the corresponding counter-elements, so that the use of unsuitable, non-fitting foreign filter inserts is in this way prevented. 
         [0033]    Preferably, the actuating elements are situated on the lower end disk and/or on a central supporting lattice of the filter insert, where they are usefully integrally formed on in one piece. 
         [0034]    Concretely, the actuating elements are preferably formed by two or more axially running ribs that protrude inward radially, or by a toothed configuration having a plurality of radially inward-protruding teeth that run axially. 
         [0035]    The first positioning guide means are also preferably situated on the lower end disk and/or on a central supporting lattice of the filter insert, and usefully are also integrally formed on in one piece. 
         [0036]    Advantageously, the actuating elements for the pusher lugs can be identical with the first positioning guide means provided on the filter insert, resulting in a favorable integration of a plurality of functions. 
         [0037]    Alternatively, the actuating elements for the pusher lugs on the one hand and the first positioning guide means provided on the filter insert on the other hand can also be fashioned separately, facilitating an individual optimization for the particular purpose. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0038]    In the following, exemplary embodiments of the present invention are explained on the basis of a drawing. 
           [0039]      FIG. 1  through  FIG. 21  show a first exemplary embodiment in various representations and various operating states, 
           [0040]      FIGS. 22 and 23  show a second exemplary embodiment in two different operating states, 
           [0041]      FIGS. 24 and 25  show a third exemplary embodiment in two different operating states, 
           [0042]      FIG. 26  through  FIG. 33  show a fourth exemplary embodiment in various representations and various operating states, and 
           [0043]      FIG. 34  through  FIG. 40  show a fifth exemplary embodiment in various representations and various operating states. 
       
    
    
       [0044]    In the following description of the Figures, identical parts in the various Figures are always designated by the same reference characters, so that not all reference characters have to be explained anew in connection with each Figure. 
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0045]      FIGS. 1 through 21  show a first exemplary embodiment of a liquid filter  1 , such as an oil filter of an internal combustion engine. 
         [0046]      FIG. 1  shows a preassembled assembly  6  made up of a filter insert  2 , a screw cover  11 , a closing pin  3 , a valve body carrier  40 , and a helical spring  5 . Filter insert  2  is locked to cover  11  via locking connection means  11 . 2  and  22 . 2 . In addition, filter insert  2  is locked to valve body carrier  40  via second locking connection means  26  and  46 . Closing pin  3  is guided in axially displaceable fashion with a guide segment  30  in a lower segment of valve body carrier  40 , and is limited in its displacement path relative to valve body carrier  40  by locking tongues  31 . Helical spring  5  surrounds guide segment  30  of closing pin  3  and is held thereon by holding cams  35 , as long as spring  5  is relaxed and therefore has its smallest inner diameter. 
         [0047]    As is standard, filter insert  2  is made up of a filter material body  22  and end disks  21  and  22  enclosing it at the ends. Lower end disk  21  has a central mounting opening  21 ′ by which filter insert  2  is mounted at the front onto valve body carrier  40 . A valve seat  24  for a filter bypass valve  4  is integrally formed in one piece on upper end disk  22 , on its downward-oriented side. In the interior of filter material body  20  there is situated a supporting lattice  23  that supports filter material body  20  against collapse during filter operation. 
         [0048]    Valve body carrier  40  is fashioned as an oblong lattice-shaped body made of carrier struts  42  that run in the circumferential and axial direction. On the upper end of valve body carrier  40  there is integrally formed a valve body  44  that together with valve seat  24  forms filter bypass valve  4 . A lower segment of valve body carrier  40  protrudes downward from filter insert  2  and forms a guide for guide segment  30  of closing pin  3 . In the lower end region of closing pin  3 , on this pin there are formed two radially sealing seals, axially at a distance from one another, seal  33 . 1  having a larger diameter and seal  33 . 2  having a smaller diameter. 
         [0049]    Preassembled assembly  6  shown in  FIG. 1  can for example be provided by a supplier to the manufacturer of internal combustion engines, who then provides the associated filter housing (not shown in  FIG. 1 ) and installs assembly  6  therein. 
         [0050]      FIG. 2  shows detail O from  FIG. 1  in an enlarged representation. Here, one of locking tongues  31  of closing pin  3  can be seen, situated on a part of valve body carrier  40 . Around the outer circumference of guide segment  30  of closing pin  3 , there runs spring  5 , held there by holding cam  35 . 
         [0051]      FIG. 3  shows detail N-N in an enlarged view. In the center, there is a sectional view of valve body carrier  40 . On its outer circumference, there is present, as a radially protruding bulge, second locking connection means  46 , which cooperate with second locking connection means  26  of filter insert  2 , realized as a locking tongue, and which is part of support lattice  23  of filter insert  2 . 
         [0052]      FIG. 4  shows a complete liquid filter  1  in which the preassembled assembly shown in  FIG. 1  is completely assembled into a filter housing  10 . Housing  10  and cover  11  are fashioned with a cooperating screw threading  12 , which in  FIG. 4  is screwed completely shut. Via its own positioning guide means  25  and positioning guide means  45  in the form of two chamfers on valve body carrier  40  in the circumferential direction, meeting one another obliquely running from top to bottom, filter insert  2  is brought into a particular position in which actuating elements  27  of filter insert  2  move into axial counterposition to pusher lugs  37  of closing pin  3 . Via actuating elements  27 , a thrust force is exerted on pusher lugs  37  that brings closing pin  3  into its closed position in filter housing  10 , shown in  FIG. 4 . 
         [0053]    In its lower part, filter housing  10  has a number of channels that are used for the supply and carrying off of liquids. Via a raw liquid inlet  15 , unfiltered liquid is guided to the raw side of liquid filter  1 , situated radially outwardly from filter insert  2 . In raw liquid inlet  15 , the liquid here flows via a first connecting channel  14 . 1  that connects liquid filter  1  to a heat exchanger (not shown) such as an oil cooler. Via a clean liquid outlet  16 , filtered liquid that flows downward from the clean side of liquid filter  1 , i.e., from a region inside filter insert  2 , exits filter housing  10 . 
         [0054]    At the very bottom of filter housing  10  there is a central discharge duct  13  in which the two seals  33 . 1  and  33 . 2  of closing pin  3  are situated. A second connecting channel  14 . 2  connects the heat exchanger to a region of central discharge duct  13  between the two seals  33 . 1  and  33 . 2 . 
         [0055]    Central discharge duct  13  has two segments,  13 . 1  having a larger diameter and  13 . 2  having a smaller diameter, in which seals  33 . 1  and  33 . 2  are situated in their sealing position, i.e., in the closed position of closing pin  3 . In this way, discharge duct  13  is sealed in liquid-tight fashion. 
         [0056]    During operation of liquid filter  1 , the liquid pressure prevailing therein ensures that closing pin  3  is held in its lowermost position. 
         [0057]    Spring  5  is supported with its lower end on filter housing  10  and with its upper end on the underside of valve body carrier  40 , and exerts an upward-directed force on this valve body carrier. This force presses valve body  44  of filter bypass valve  4  into its closed position against valve seat  24 , as long as a liquid pressure difference between the raw side and the clean side remains below a threshold value. Inside filter housing  10 , valve body carrier  40  is guided so as to be capable of limited axial displacement; a limitation of the displacement path upward is formed by a flexible cam system  41 , which does permit insertion of valve body carrier  40  from above into a corresponding central opening of filter housing  10 , but prevents valve body carrier  40  from being withdrawn from filter housing  10 . 
         [0058]      FIG. 5  shows detail Q from  FIG. 4 , in an enlarged representation. Here it can be seen particularly clearly that actuating element  27  exerts a thrust force, in the axial direction, on pusher lug  37  of closing pin  3 . 
         [0059]      FIG. 6  shows detail R from  FIG. 4  in an enlarged representation, in which the cooperation of second seal  33 . 2  of closing pin  3  with discharge duct  13  in filter housing  10  can be seen clearly. The lower end of closing pin  3  still has a small distance from a step in filter housing  10 ; when the liquid filter is commissioned, a liquid pressure arises above closing pin  3 , which ensures that closing pin  3  moves, with its lower end underneath seal  33 . 2 , until reaching a stop on housing  10 . 
         [0060]      FIG. 7  shows detail W from  FIG. 4  in an enlarged view. Here it can be seen in particular how helical spring  5  is supported with its lower side on filter housing  10  and with its upper side on valve body carrier  40 . 
         [0061]      FIG. 8  shows previously described liquid filter  1 , now in a state in which filter bypass valve  4  is open. This open position of filter bypass valve  4  occurs when there arises between the raw side, connected to raw liquid inlet  15 , and the clean side, connected to clean liquid outlet  16 , of liquid filter  1  a pressure difference that exceeds a boundary value, for example as a result of a clogging of filter material body  20  with filtered-out dirt particles. The force produced by the pressure difference presses on the upper side of valve body  44 , and thus moves valve body carrier  40  against the force of spring  5  in the opening direction, i.e., downward. In this way, valve body  44  comes to be situated at a distance from its valve seat  24  on upper end disk  23  of filter insert  2 . An immediate flow path is now open from the raw side to the clean side of liquid filter  13 . During the opening movement of valve body carrier  40  with valve body  44 , closing pin  3  maintains its position unchanged. 
         [0062]      FIG. 9  shows detail Y from  FIG. 8 , in which open filter bypass valve  4  is shown in an enlarged view. At the bottom, the upper end of valve body carrier  40  with valve body  44  is visible. At the top in  FIG. 9 , there is situated upper end disk  22  of filter insert  2  with its valve seat  24 . Here, valve body  44  is moved away from valve seat  24 , and filter bypass valve  4  is open. 
         [0063]      FIG. 10  shows detail X from  FIG. 8 , in an enlarged view. At the left and at the right, a small part of filter housing  10  can be seen, in whose central opening lower end disk  21  of filter insert  2  is inserted in sealing fashion. At the same time, filter insert  2  is mounted, with central mounting opening  21 ′, onto valve body carrier  40 , which runs from below to above into filter insert  2 . At bottom in  FIG. 10 , the upper part of guide segment  30  of closing pin  3  is visible, whose uppermost end is formed by pusher lug  37 . Radially outside guide segment  30 , cam system  41  of valve body carrier  40  is also visible. 
         [0064]      FIG. 11  shows liquid filter  1  during a maintenance session, during which cover  11  is screwed off from filter housing  10 . Filter insert  2  is lifted out along with it via locking connecting means  11 . 2  and  22 . 2 . 
         [0065]    Spring  5  pushes valve body carrier  40 , which is now relieved of stress axially at its upper side due to the removal of cover  11 , upward until its cam system  41  meets the associated step of filter housing  10 , thereby preventing further displacement of valve body carrier  40  upward. Via locking tongues  31 , described on the basis of  FIGS. 1 and 2  and not visible in  FIG. 11 , closing pin  3  is concomitantly moved upward by valve body carrier  40 . In this way, lower seal  33 . 2  moves out of segment  13 . 2  of discharge duct  13  having the smaller diameter into segment  13 . 1  of discharge duct  13  having the larger diameter, thus causing seal  33 . 2  to become free of filter housing  10  and to no longer seal. Upper seal  33 . 1  remains inside segment  13 . 1  of discharge duct  13  having the larger diameter, and thus continues to seal. 
         [0066]    In  FIG. 12 , detail P from  FIG. 11  is shown in an enlarged view. Here, in particular the cooperation of the second locking connecting means  26  and  46  is clear. 
         [0067]      FIG. 13  shows the state after the removal of cover  11  and the removal of filter insert  2 , connected thereto, from filter housing  10 . Spring  5  now presses valve body carrier  40  upward up to the stop point of its cam system  41  on filter housing  10 . Closing pin  3 , carried along upward by the valve body carrier  40 , continues to be in its open position. When closing pin  3  is in the open position, liquid in filter housing  10  flows through raw liquid inlet  15 , through first connecting channel  14 . 1  and through the heat exchanger connected thereto (not shown here), via second connecting channel  14 . 2 , past lower seal  33 . 2 , through discharge duct  13 , and, in the case of an oil filter, preferably into the oil pan of an associated internal combustion engine. 
         [0068]      FIG. 14  shows the partly disassembled liquid filter of  FIG. 13 , in a longitudinal section rotated by 90°. In the lower part of filter housing  10  there is again situated closing pin  3  with its two seals  33 . 1  and  33 . 2 , of which the latter stands free from filter housing  10  and thus releases discharge duct  13 . Guide segment  30 , forming the upper part of closing pin  3 , is guided axially in the lower part of valve body carrier  40 , where the capacity for relative axial displacement is limited by locking tongues  31 . Moreover, locking tongues  31  provide rotational securing of closing pin  3  and valve body carrier  40  relative to one another. On the part of valve body carrier  40  situated above guide segment  30 , its positioning guide means  45  can be seen, in the form of the chamfers running over its outer circumference and falling off in opposite directions. 
         [0069]      FIG. 15  shows detail U from  FIG. 13  in an enlarged view, in which in particular it can be seen that cam system  41  lies against the associated step of filter housing  10 . 
         [0070]      FIG. 16  shows detail V from  FIG. 14  in an enlarged view. Here the interaction of locking tongues  31  with valve body carrier  40  can be seen clearly, whereby closing pin  3  is carried along upward when there is an upward movement of valve body carrier  40 . 
         [0071]      FIG. 17  shows, in a partially broken-away perspective view, filter housing  10  together with valve body carrier  40  inserted therein. Facing the observer, on the side of housing  10  raw liquid inlet  15  running therein can be seen. On the valve body carrier  40 , facing the observer positioning guide means  45  can be seen, which force-guide positioning guide means  25  on filter insert  2 , which here are at the same time actuating elements  27 , into a position in the circumferential direction ready for engagement with pusher lugs  37  of closing pin  3 . 
         [0072]      FIG. 18  shows an enlarged segment of liquid filter  1  in eccentric longitudinal section. At the top in  FIG. 18 , a part of filter material body  20 , lower end disk  21 , and supporting lattice  23  of filter insert  2  can be seen. Filter insert  2  is shown in a state during its placement onto valve body carrier  40 , where filter insert  2 , seen in the circumferential direction, has not yet reached its engagement-ready position relative to closing pin  3 . Rather, positioning guide means  25  of filter insert  2  have been placed from above, in the axial direction, into an intermediate position onto positioning guide means  45  of valve body carrier  40 . Subsequently, filter insert  2  rotates in the clockwise direction and at the same time moves further downward, and positioning guide means  25  slide onto positioning guide means  45 . At the end of this movement, positioning guide means  25 , which at the same time form actuating elements  27 , are situated in fitting counterposition to pusher lugs  37  on closing pin  3 . 
         [0073]      FIG. 19  shows liquid filter  1  in a state at the beginning of assembly after a filter maintenance. Cover  11  of filter housing  10 , together with filter insert  2  locked thereto, is screwed to a small extent into screw threading  12 . In this state, actuating elements  27  of filter insert  2  are still at an axial distance from pusher lugs  37  of closing pin  3 . Valve body carrier  40  is still in its position pushed out upward by spring  5 , in which its cam system  41  lies against filter housing  10 . Closing pin  3 , carried along upward by valve body carrier  40 , is also still in its raised opening position, in which it is held by the friction of upper seal  33 . 1 . 
         [0074]      FIG. 20  shows detail X from  FIG. 19  in an enlarged view, such that on the one hand the stop of cam system  41  on filter housing  10  and on the other hand the axial distance between actuating elements  27  and pusher lugs  37  is clear. 
         [0075]      FIG. 21  shows liquid filter  1  from  FIG. 19 , now in a state after cover  11  has been screwed somewhat further into filter housing  10 . In the state shown in  FIG. 21 , actuating elements  27  are now just axially seated on pusher lugs  37 . Valve body carrier  40  has already been moved concomitantly downward by a small distance through the seating of valve body  44  on sealing seat  24 , which can be seen in that now cam system  41  already has a slight axial distance downward from the associated step in filter housing  10 . The movement of cover  11  downward has still not been transmitted to closing pin  3 . 
         [0076]    After further screwing of cover  11  into filter housing  10  up to the stop point, there results the state of liquid filter  1  shown in  FIG. 4 , in which closing pin  3  is again in its closing position. 
         [0077]      FIGS. 22 and 23  show a second exemplary embodiment, modified compared to the example shown in the preceding Figures. Differing from the first example, filter housing  10  of liquid filter  1  according to  FIGS. 22 and 23  has, in discharge duct  13 , a third segment  13 . 3  that is situated above segments  13 . 1  and  13 . 2  and that has the largest inner diameter compared to the two segments  13 . 1  and  13 . 2 . This segment  13 . 3  terminates upwardly at segment  13 . 1 . 
         [0078]    In the closing position of closing pin  3 , as is present in the normal operation of the liquid filter, seal  33 . 1  is situated in sealing fashion in segment  13 . 1  and seal  33 . 2  is situated in sealing fashion in segment  13 . 2  of discharge duct  13 . 
         [0079]      FIG. 23  shows the liquid filter from  FIG. 22  after the removal of cover  11  and removal of filter insert  2 . In this state, spring  5  presses valve body carrier  40  upward until the stop point of its cam system  41  on filter housing  10 , whereby valve body carrier  40  also carries closing pin  3  upward into its uppermost position. In this uppermost position of closing pin  3 , upper seal  33 . 1  is situated freely in segment  13 . 3  and lower seal  33 . 2  is situated freely in segment  13 . 1  of discharge duct  13 . In this way, a runoff path for liquid is released from filter housing  10  through its central opening along the lower part of valve body carrier  40  and along closing pin  3 , past its two seals  33 . 1  and  33 . 2 , into discharge duct  13 . Parallel to this, another part of the liquid can flow through raw liquid inlet  15 , first connecting channel  14 . 1 , an associated heat exchanger (not shown here), a second connecting channel  14 . 2  coming from the heat exchanger, past lower seal  33 . 2 , into discharge duct  13 . In addition, on this second path the heat exchanger is also emptied during the filter maintenance. 
         [0080]    In all further individual parts and functions, liquid filter  1  according to  FIGS. 22 and 23  corresponds to the previously explained exemplary embodiment, to whose description reference is made. 
         [0081]    A third exemplary embodiment of the present invention is shown in  FIGS. 24 and 25 . Characteristic for this embodiment of liquid filter  1  is that here closing pin  3  has only one radially sealing seal  33 , and that discharge duct  33  in filter housing  10  has only two segments  13 . 1  and  13 . 3  for cooperation with seal  33 . 
         [0082]    In  FIG. 24 , liquid filter  1  is shown in its operating position in which filter insert  2  is installed in filter housing  10  and cover  11  is screwed tightly onto filter housing  10 . In this state, as in the examples described above, actuating elements  27  press against pusher lugs  37  of closing pin  3 , and in this way move it downward, or holds it in its lower position. In this position, seal  33  is situated in sealing fashion in segment  13 . 1  of discharge duct  13 , which is sealed in liquid-tight fashion thereby. Liquid that is to be filtered moves through raw liquid inlet  15  into liquid filter  1 , and leaves the filter, after flowing through filter material body  20  of filter insert  2 , through clean liquid outlet  16 . Here, a heat exchanger is not assigned to liquid filter  1 . 
         [0083]    In  FIG. 25 , the liquid filter is shown from  FIG. 24  after removal of cover  11  and removal of filter insert  2 . Here as well, spring  5  has now pressed valve body carrier  40  upward until the stop of its cam system  41  on filter housing  10 . Via locking tongues system  31 , shown and explained in  FIGS. 1 ,  2 ,  14 , and  16 , and not visible in  FIG. 25 , closing pin  3  is carried along upward, into its uppermost position shown in  FIG. 25 . In this position, seal  33  is situated freely in segment  13 . 3  of discharge duct  13 , so that this duct is open. Liquid in filter housing  10  can in this way flow through the central opening of housing  10 , along the lower part of valve body carrier  40 , and along closing pin  3 , past seal  33 , through discharge duct  13 . 
         [0084]    In all further individual parts and functions, liquid filter  1  according to  FIGS. 24 and 25  corresponds to the previously explained exemplary embodiments, to whose description reference is made. 
         [0085]      FIGS. 26 through 33  of the drawing show a fourth exemplary embodiment of liquid filter  1 . For this example, it is characteristic that it does not have any positioning guide means on filter insert  2  and on the valve body carrier  40 . Here, actuating elements  27  on the lower side of lower end disk  21  of filter insert  2  are fashioned as annular circumferential collars that, in any rotational position of filter insert  2  relative to valve body carrier  40  and to closing pin  3 , enter into engagement with pusher lugs  37  thereof. 
         [0086]    In  FIG. 26 , liquid filter  1  is shown in a state at the beginning of assembly in the context of maintenance after fastening a fresh filter insert  2  in cover  11  and after an initial screwing of cover  11  into filter housing  10 . Due to the previous removal of cover  11  and removal of filter insert  2 , closing pin  3  and the valve body carrier  40  are still in their respective uppermost position. In the state according to  FIG. 26 , actuating elements  27  still have a small axial distance from pusher lugs  37  of closing pin  3 . 
         [0087]      FIG. 27  shows detail X from  FIG. 26  in an enlarged view. At left, a part of filter housing  10  is visible. At the top, the end region of filter insert  2  can be seen, namely parts of its lower end disk  21 , of filter material body  20 , and of supporting lattice  23 . In its center, lower end disk  21  has central mounting opening  21 ′, which is limited at the lower side by the circumferential collar forming actuating elements  27 . 
         [0088]    At a small axial distance below actuating elements  27 , there is situated one of pusher lugs  37  of closing pin  3 . In the lower part of  FIG. 27 , between guide segment  30  of closing pin  3  and filter housing  10  a cam of cam system  41  can be seen, which is seated on the associated step of filter housing  10 . 
         [0089]    In  FIG. 28 , liquid filter  1  from  FIG. 26  is shown in a state that arises after cover  11  is screwed slightly further into filter housing  10 . Filter insert  2  is now moved downward, together with cover  11 , far enough that actuating elements  27  just meet pusher lugs  37  of closing pin  3 . Because the valve body carrier  40  is already seated on valve seat  24  with its valve body  44 , valve body carrier  40  is already moved downward by a small distance, which can be seen in that the cam system  41  now has a small axial distance from the associated step of filter housing  10 . 
         [0090]    This state is shown in detail Y from  FIG. 28 , illustrated in  FIG. 29  in an enlarged view. Here, in particular the seating of actuating elements  27  on pusher lugs  37  and the small axial distance of cam system  41  from the associated step of filter housing  10  can be seen. 
         [0091]      FIG. 30  shows liquid filter  1 , now in its completely assembled state, in which cover  11  is screwed tightly to filter housing  10 . Via actuating elements  27  on filter insert  2 , closing pin  3  is pressed into its lowermost position, as is valve body carrier  40  by filter insert  2 . In this position, seals  33 . 1  and  33 . 2  are situated in sealing position in segments  13 . 1  and  13 . 2  of discharge duct  13 , whereby this duct is tightly sealed. Filter insert  2  is seated with its lower end disk  21  in sealing fashion in the central opening of filter housing  10 , and filter bypass valve  4  at the upper end of valve body carrier  40  is closed, and as a result a flow connection from the raw side to the clean side exists only through filter material body  20  of filter insert  2 . 
         [0092]      FIG. 31  shows detail Z from  FIG. 30  in an enlarged view. 
         [0093]      FIG. 32  shows liquid filter  1  from  FIG. 30  in a longitudinal section rotated by 90° along the line A-A. In this sectional plane, the position of locking tongues  31  on guide segment  30  of closing pin  3  in openings of the lower region of valve body carrier  40  can be seen, whereby valve body carrier  40  guides closing pin  3  so as to be capable of limited axial displacement. 
         [0094]    In  FIG. 33 , detail W from  FIG. 32  is shown in an enlarged view. 
         [0095]    In all further individual parts and functions, liquid filter  1  according to  FIGS. 26 through 33  corresponds to the above-explained first exemplary embodiment, to whose description reference is made. 
         [0096]      FIGS. 34 through 40 , finally, show a fifth exemplary embodiment of the present invention. This exemplary embodiment corresponds essentially to the previously described fourth exemplary embodiment; in the fifth exemplary embodiment, the shape of actuating elements  27  on lower end disk  21  of filter insert  2  is different. Adapted thereto, valve body carrier  40  is also realized somewhat differently than in the fourth exemplary embodiment. 
         [0097]      FIG. 34  shows liquid filter  1  in its normal operating position. Cover  11  is connected to filter housing  10  together with filter insert  2 . Via actuating elements  27  of filter housing  2 , closing pin  3  is pressed downward into its closing position, and valve body carrier  40 , loaded by the force of spring  5 , lies with its valve body  44  against valve seat  24  of upper end disk  22  of filter insert  2 . 
         [0098]      FIG. 35  shows detail X from  FIG. 34  in an enlarged view. 
         [0099]      FIG. 36  shows a section through the liquid filter according to the line A-A in  FIG. 35 . Filter housing  10  is sectioned radially outwardly. Radially inwardly, lower end disk  21 , with its central mounting opening  21 ′, is situated therein. With mounting opening  21 ′, lower end disk  21  is mounted onto valve body carrier  40 , and with said lower end disk the rest of filter insert  2  (not visible here) is mounted onto the valve body carrier  40 . Actuating elements  27  on the inner circumference of central mounting opening  21 ′ of lower end disk  21  are here formed by radially inward-protruding teeth that are at a distance from one another in the circumferential direction. Each pair of oppositely situated teeth fit between two short ribs that run in the axial direction and that form positioning guide means  45  on valve body carrier  40 . In this way, a key-lock system is realized that prevents the use of unsuitable foreign filter inserts in liquid filter  1  according to the present invention. 
         [0100]      FIG. 37  shows a view of a valve body carrier  40  as an individual part. Valve body carrier  40  has the form of a lattice-shaped hollow cylindrical body made up of carrier struts  42  that run in the circumferential direction and in the longitudinal direction. At the very top of valve body carrier  40 , here dome-shaped valve body  44  is integrally formed on in one piece. At a distance under this, second locking connection means  46  are situated in the form of a circumferential locking bulge. Still further downward there follow positioning guide means  45  on the outer circumference of valve body carrier  40 , which cooperate with actuating elements  27  of filter insert  2  as described above. Finally, on the lowermost segment of valve body carrier  40 , cam system  41  can be seen having the two oppositely situated flexible locking tongues that carry the cams. 
         [0101]      FIG. 38  shows lower end disk  21  of filter insert  2  of liquid filter  1  from  FIG. 34 , in cross section as an individual part. Here, the toothing situated on the inner circumference of central mounting opening  21 ′, for the formation of actuating elements  27 , can be seen particularly clearly. The individual teeth are distributed uniformly in the circumferential direction and run in the axial direction of end disk  21 . Each tooth has on its lower end run-in chamfers that facilitate the running in of the two teeth cooperating with positioning guide means  45  on valve body carrier  40 . 
         [0102]      FIG. 39  shows a plan view of end disk  21 . Here in particular the regular configuration of the teeth, forming actuating elements  27 , of the toothing on the inner circumference of central mounting opening  21 ′ can be seen clearly. 
         [0103]    Finally,  FIG. 40  shows, in a perspective view, the cooperation of closing pin  3 , valve body carrier  40 , and end disk  21 . At the top in  FIG. 40 , valve body carrier  40  can be seen with its valve body  44  and with second locking connection means  46 . Closing pin  3  is inserted from below into valve body carrier  40  and is locked there. From above, end disk  21  is mounted onto valve body carrier  40 , said end disk cooperating, via its tooth-shaped actuating elements  27 , with positioning guide means  45  on valve body carrier  40 , in the manner of a key-lock system. Via each of the actuating elements  27  that come to be situated between positioning guide means  45 , closing pin  3  is actuated downward in the direction of insertion relative to filter housing  10 . In this way, the use of an unsuitable foreign filter insert having a lower end disk that has a smooth inner circumference is prevented, because such a foreign filter insert would not be able to push connecting pin  3  downward into its sealing closing position. In this case, the discharge duct would then remain open, and it would not be possible for a liquid pressure to build up in liquid filter  1 . In the case of an oil filter of an internal combustion engine, this would be signaled for example by illumination of the oil pressure warning lamp. A corresponding pressure sensor can for example be connected to a pressure sensor connection  17  on filter housing  10 . 
         [0104]    For reasons of durability, filter housing  10  of liquid filter  1  is preferably made of a light metal such as aluminum, and is usefully produced using a die-casting method. Connecting pin  3  and valve body carrier  40 , as well as end disks  21  and  22  and supporting lattice  23  of filter insert  2 , are preferably made of a plastic such as polyamide, for reasons of weight and disposability, and are usefully injection-molded parts. 
         [0105]    As is apparent from the foregoing specification, the invention is susceptible of being embodied with various alterations and modifications which may differ particularly from those that have been described in the preceding specification and description. It should be understood that I wish to embody within the scope of the patent warranted hereon all such modifications as reasonably and properly come within the scope of my contribution to the art. 
       LIST OF REFERENCE CHARACTERS 
       [0000]    
       
           1  liquid filter overall 
           10  filter housing 
           11  removable cover 
           11 . 2  locking connection means for  22 . 2   
           12  screw threading 
           13  discharge duct 
           13 . 1 ,  13 . 2 ,  13 . 3  segments of  13   
           14 . 1 ,  14 . 2  connecting channels 
           15  raw liquid inlet 
           16  clean liquid outlet 
           17  pressure sensor connection 
           2  filter insert 
           20  filter material body 
           21  lower end disk 
           21 ′ central mounting opening in  21   
           22  upper end disk 
           22 . 2  locking connection means for  11 . 2   
           23  support lattice in  20   
           24  valve seat in  22   
           25  positioning guide means on  2   
           26  second locking connection means 
           27  actuating elements on  2  for  37   
           3  connecting pin 
           30  guide segment in  4   
           31  locking tongues 
           33 ,  33 . 1 ,  33 . 2  seals on  3   
           35  holding cams for  5   
           37  pusher lugs 
           4  filter bypass valve 
           40  valve body carrier 
           41  cam system 
           42  carrier struts 
           44  valve body 
           45  positioning guide means on  4   
           46  second locking connection means 
           5  spring 
           6  preassembled assembly