Abstract:
In order to improve an oil separator unit, in particular an oil separator unit provided for vehicle drives, comprising an oil separator housing with a drainage system and a check valve unit which is formed from a valve seat and a valve element which comprises a valve member of an umbrella-like design and consisting of an elastomer, in such a manner that it can be produced as inexpensively as possible, on the one hand, and, on the other hand, the wear on the valve element is, however, considerably reduced or occurs to as low a degree as possible, it is suggested that the valve member of the valve element be held on an insert part and that the insert part be insertable, for its part, into an insert part receptacle in a valve housing.

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS 
       [0001]    The present disclosure relates to the subject matter disclosed in German application number 10 2010 062 321.0 of Dec. 2, 2010, which is incorporated herein by reference in its entirety and for all purposes. 
       BACKGROUND OF THE INVENTION 
       [0002]    The invention relates to an oil separator unit, in particular an oil separator unit provided for vehicle drives, comprising an oil separator housing with a drainage system and a check valve unit which is formed from a valve seat and a valve element which comprises a valve member of an umbrella-like design and consisting of an elastomer. 
         [0003]    Oil separator units of this type are preferably arranged on or in crankcases, on or in the oil sump housing, on or in cylinder heads or camshaft chamber covers of combustion engines, in particular in crankcases or camshaft chamber venting systems of combustion engines. 
         [0004]    The problem with such oil separator units with a check valve is that the valve element is subject to wear on account of the pressure pulsations and vibrations occurring in the engine and the friction resulting therefrom, wherein the wear manifests itself to the extent that the valve element tears or even to the extent that part of the valve element becomes detached. 
         [0005]    Wear problems of this type lead to an impairment of the operability or to the fact that the resources required during production to fix the valve element in place on the check valve unit are high. 
         [0006]    The object underlying the invention is, therefore, to improve an oil separator unit of the generic type in such a manner that it can be produced as inexpensively as possible, on the one hand, and, on the other hand, the wear on the valve element is, however, considerably reduced or occurs to as low a degree as possible. 
       SUMMARY OF THE INVENTION 
       [0007]    This object is accomplished in accordance with the invention, in an oil separator unit of the type described at the outset, in that the valve member of the valve element is held on an insert part and that the insert part can, for its part, be inserted into an insert part receptacle in a valve housing. 
         [0008]    The advantage of the solution according to the invention is to be seen in the fact that, as a result, it is possible to produce the insert part as a separate part and design it with its surfaces holding the valve element in such a manner that wear on the valve element, in particular in the region of the surfaces holding it, is considerably diminished and, where possible, can be reduced to a negligible degree. 
         [0009]    It is, in addition, particularly advantageous when, due to the fact that the valve element is held on the insert part, the valve element and the insert part can be preassembled and, therefore, the insert part can be inserted into the valve housing with the preassembled valve element, which likewise makes the handling of the valve element and the assembly thereof in the valve housing considerably easier. 
         [0010]    With respect to the design of the insert part receptacle, it would be conceivable, for example, to also design this as a separate part which can be assembled on the valve housing. 
         [0011]    The insert part can be designed in several parts, particularly when the installation is simplified as a result. 
         [0012]    One favorable solution provides, however, for the insert part receptacle to be integrally formed on the valve housing in one piece so that the advantage of the simple production of the insert part receptacle in one piece with the valve housing can be exploited since the connection between the insert part receptacle and the insert part does not have the problems which result when fixing in place the holding attachment of the valve element which is formed from an elastomer. 
         [0013]    The insert part can also, for example, be designed in several pieces, for example in order to make its production easier. 
         [0014]    A solution which is particularly advantageous for reasons of cost provides, however, for the insert part to be designed as a one-piece part. 
         [0015]    With respect to the fixing of the insert part in the insert part receptacle, the most varied of possibilities are conceivable. 
         [0016]    In principle, it is conceivable to fix the insert part in the insert part receptacle in a force locking manner, for example by means of a thread, wherein an exclusively force locking fixing in position can be a problem with respect to the continuous durability. 
         [0017]    For this reason, one particularly favorable solution provides for the insert part to be held in the insert part receptacle in a form locking manner. 
         [0018]    Such a form locking fixing could be brought about, for example, via a bayonet connection. 
         [0019]    A particularly simple solution provides, however, for the insert part to be lockable in the insert part receptacle. 
         [0020]    Another, advantageous possibility for fixing the insert part in place in the insert part receptacle provides for the insert part to be fixed in the insert part receptacle in a materially locking manner. 
         [0021]    Such a materially locking fixing of the insert part in the insert part receptacle may be realized, for example, by gluing the insert part to the insert part receptacle. 
         [0022]    Another, advantageous solution may be realized by welding the insert part to the insert part receptacle. 
         [0023]    In order to ensure that the oil does not collect in the region of the insert part, it is preferably provided for the insert part to have at least one opening for oil. 
         [0024]    The design of the valve element can be brought about in the most varied of ways. 
         [0025]    For example, the valve element can be designed such that it comprises only the valve member. 
         [0026]    In this case, one advantageous solution provides for the valve member to be held directly on the insert part. 
         [0027]    Another possibility provides for the valve member to be connected to the insert part so as to be movable. 
         [0028]    For example, this can be realized in that the valve member is guided for movement on the insert part, either on its circumferential side or through a central opening. 
         [0029]    One particularly favorable solution in the case of a movable connection between the valve member and the insert part provides for the valve member to be provided with a holding attachment of the valve element. 
         [0030]    In this respect, the holding attachment is preferably integrally formed on the valve member in one piece. 
         [0031]    In this respect, the holding attachment can be arranged so as to be located radially outwards or be connected to the valve member as a central attachment. 
         [0032]    In principle, it would be possible with the solution according to the invention, on account of the elastic configuration of the valve member, to realize the opening and closing of the check valve unit by way of elastic deformation so that the valve member lifts away from the valve seat or rests on the valve seat on account of its elastic deformation. 
         [0033]    This would, however, result in the check valve only opening when the oil collecting above the check valve exerts an adequate hydrostatic pressure on account of a relatively large oil column. 
         [0034]    For this reason, it is preferably provided for the valve member to be movable as a whole relative to the valve seat between a closed position and an open position. 
         [0035]    This means that the entire valve member can be moved relative to the valve seat in order to transfer from the closed position into the open position or vice versa. 
         [0036]    In this case, an elastic deformation of the valve member is merely necessary for the purpose of being able to achieve a sealed closure of the valve member with the valve seat in the closed position. 
         [0037]    Such movability of the valve member between the closed position and the open position may preferably be brought about in that the valve member is guided for movement between the closed position and the open position in order to avoid any faulty functioning of the check valve, in particular any unreliable closing thereof. 
         [0038]    Such faulty functioning of the check valve occurs, in particular, when the valve member tilts during its movement between the closed position and the open position or vice versa and can, therefore, no longer move in the desired manner. 
         [0039]    For this reason, one advantageous solution provides for the valve member to be guided between the closed position and the open position essentially free from any canting so that a reliable functioning of the valve member can be ensured. 
         [0040]    Such canting-free guidance of the valve member between the open position and the closed position can be realized in the most varied of ways. 
         [0041]    Such canting-free guidance of the valve member may be achieved particularly advantageously when this canting-free guidance is brought about by guidance within the insert part, i.e. in the case of an insert part designed in two parts, or by a relative movement of the insert part in the insert part receptacle so that the guidance for the movability of the valve member results between the insert part and the receptacle. 
         [0042]    Another advantageous embodiment provides for the holding attachment of the valve member to be guided for movement in the insert part and, as a result, guidance of the valve element and, in particular, of the valve member can be realized. 
         [0043]    With respect to the accommodation of the valve element in the insert part, no further details have so far been given. 
         [0044]    The reduction in wear on the valve element may be realized, in particular, in that the insert part accommodates the valve element with burr-free surfaces. 
         [0045]    In addition, it is particularly favorable when the insert part accommodates the valve element with machined surfaces, wherein machined surfaces are to be understood such that they have a surface roughness acting on the elastomeric material of the valve element free from wear. 
         [0046]    Furthermore, it is preferably provided for the insert part to abut on the valve element with surfaces merging into one another with radii&gt;0.2 millimeters. 
         [0047]    The surfaces abutting on the valve element may be realized particularly advantageously when the insert part is formed from a plastic material free of reinforcing fibers. 
         [0048]    The insert part may be expediently realized from the plastic material which represents the matrix material of the valve housing. 
         [0049]    One particularly favorable solution provides for the insert part to have a ring member for accommodating the valve element since such a ring member is in a position to accommodate the valve element in a particularly careful manner with especially little wear. 
         [0050]    Furthermore, it is advantageous when the ring member has a rounded ring inner side, with which it abuts on the valve element. 
         [0051]    Alternatively thereto, one advantageous solution provides for the insert part to have a holding sleeve. 
         [0052]    It is expediently provided in the case of such a holding sleeve for this to abut on the valve element with a rounded supporting bead. 
         [0053]    With respect to the design of the insert part receptacle for accommodating the insert part, the most varied of solutions are conceivable. 
         [0054]    One advantageous solution provides for the insert part receptacle to accommodate the insert part at least partially. 
         [0055]    With this solution it is provided, for example, for the valve element to be arranged outside the insert part receptacle. 
         [0056]    Another advantageous solution provides for the insert part receptacle to accommodate the insert part completely. 
         [0057]    Irrespective of whether the insert part receptacle accommodates the insert part partially or completely, the arrangement of the valve element can be optional. 
         [0058]    Even when the insert part receptacle accommodates the insert part completely, it is possible, in particular, to arrange the valve element outside the insert part receptacle. 
         [0059]    One particularly favorable solution provides for the insert part receptacle to accommodate the valve element. 
         [0060]    Such a solution has the advantage that, as a result, the valve element can be secured in addition by the insert part receptacle even in the case of partial wear and tear or loosening of parts. 
         [0061]    In this respect, a solution, with which the valve element is arranged in a space formed between the insert part and the insert part receptacle, is particularly advantageous. 
         [0062]    In this case, it is possible to secure the valve element in place, in particular the valve member thereof, even if the valve element were to loosen from the holding attachment as a result of wear and tear since the valve element can still be held in the space formed between the insert part and the insert part receptacle. 
         [0063]    With respect to the design of the valve seat, no further details have so far been given. 
         [0064]    It would be conceivable, for example, to provide a separate element, which can be fixed in place on the valve housing, for the formation of the valve seat, as well. 
         [0065]    However, a solution, with which the valve seat is formed on the valve housing, is particularly inexpensive. 
         [0066]    A solution which is likewise advantageous and inexpensive provides for the valve seat to be formed on the insert part. 
         [0067]    In this case, it is likewise possible to produce the valve seat with a surface quality which allows the valve element, in particular the valve member, to abut on the valve seat free of wear and tear. 
         [0068]    It is, in particular, possible to produce the valve seat burr-free and with a preferred surface quality either by way of machining or by way of other measures. 
         [0069]    In this respect, it proves to be a particular advantage when the insert part is produced from a plastic material free of reinforcing fibers since such a material is easy to machine and can, therefore, be produced with a high surface quality. 
         [0070]    In order to give the valve housing and also, in particular, the oil separator housing the necessary stability and resistance to fatigue, it is preferably provided for the oil separator housing and/or the valve housing to be formed from a fiber-reinforced plastic material since this increases the mechanical strength and the temperature stability. 
         [0071]    Such a fiber-reinforced plastic material may not be machined with a high surface quality. This is, however, irrelevant in the case where an insert part is used since the surface quality is not critical in the case of the interaction between the insert part and the insert part receptacle. 
         [0072]    Additional features and advantages of the invention are the subject mater of the following description as well as the drawings illustrating several embodiments. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0073]      FIG. 1  shows an overall illustration of an oil separator unit according to the invention as part of a vehicle engine; 
           [0074]      FIG. 2  shows a section through a first embodiment of a drainage system according to the invention with a check valve unit; 
           [0075]      FIG. 3  shows a section similar to  FIG. 2  through a second embodiment of an oil separator unit according to the invention with a check valve unit; 
           [0076]      FIG. 4  shows a section similar to  FIG. 2  through a third embodiment of an oil separator unit according to the invention with a check valve unit; 
           [0077]      FIG. 5  shows a section similar to  FIG. 2  of a fourth embodiment of an oil separator unit according to the invention with a check valve unit; 
           [0078]      FIG. 6  shows a section similar to  FIG. 2  through a fifth embodiment of an oil separator unit according to the invention with a check valve unit; 
           [0079]      FIG. 7  shows a section similar to  FIG. 2  through a sixth embodiment of an oil separator unit according to the invention with a check valve unit and 
           [0080]      FIG. 8  shows a section similar to  FIG. 2  through a seventh embodiment of an oil separator unit according to the invention with a check valve unit. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0081]    An oil separator unit, which is illustrated in  FIG. 1 , designated as a whole as  10  and integrated, for example, into a crankcase section or a camshaft chamber cover of a combustion engine, comprises an oil separator housing  12  which has a ventilating gas E flowing through it and is provided with a drainage system  14  which comprises an oil collecting device  16  and a check valve unit  18  which is associated therewith and has a valve housing  20  which serves the purpose of discharging oil from the oil collecting device  16  into a chamber R, for example into a crankcase or a camshaft chamber, but preventing any flow back of oil or gas from the chamber R into the oil collecting device  16 . 
         [0082]    A first embodiment of such a drainage system  14  according to the invention, illustrated in  FIG. 2 , comprises a valve support  24  which is integrally formed on a base  22  of the oil collecting device  16  and is designed, for example, as a sleeve which adjoins the base  22  and on its end side  26  facing away from the base  22  forms a valve seat  28 , on which a valve element designated as a whole as  30  and comprising a valve member  32  of an umbrella-like design can abut with an outer umbrella edge  34 . 
         [0083]    The valve member  32  serves the purpose of closing an opening  44  in the base  22  which is surrounded by the valve seat  28 , wherein the valve seat  28  is arranged on the valve seat support  24  and, therefore, on the base  22  on a side facing the valve member  32  and extending around the opening  44 . 
         [0084]    The umbrella-like valve member  32  extends from a central area  36  in a curved manner as far as the outer umbrella edge  34 , wherein the valve member  32  has an outer side  38  which is curved convexly and is located so as to face away from the valve seat  28  as well as an inner side  40  which is curved concavely. 
         [0085]    In a closed position of the check valve unit  18 , the umbrella edge  34  abuts on the valve seat  28  and thereby extends in a plane  42 , in which the valve seat  28  is also located, wherein for the abutment of the umbrella edge  34  on the valve seat  28  acted upon by a force the valve member  32  can be elastically pretensioned between the central area  36  and the umbrella edge  34 . 
         [0086]    A holding attachment  50  is integrally formed on the central area  36  of the valve member  32  in one piece and rises above the concavely curved inner side  40  and beyond the umbrella edge  34  and engages with a holding pin  52  in an insert part  60  which has, for example, a holding sleeve  62 , into the interior space  64  of which the holding pin  52  extends and is fixed in it in a form locking manner, for example by means of a collar  66  of the holding sleeve  62  which protrudes into the interior space  64  and engages in a corresponding recess  68  in the holding pin  52  so that the holding pin  52  is fixed in a form locking manner in the holding sleeve  62  in the direction of its longitudinal extension  70 , wherein the longitudinal direction  72  of the holding sleeve extends parallel to the longitudinal direction  70 . 
         [0087]    The holding sleeve  62  is provided, in addition, at its end facing the central area  36  with a circumferential supporting bead  74  with rounded surfaces which are machined free of burrs and on which the central area  36  abuts with a corresponding recess  76  and surrounds them at least partially. 
         [0088]    The entire valve element  30 , i.e. the valve member  32  and the holding attachment  50 , are formed from an elastomeric material which is in a position, as a result of the holding sleeve  62  of the insert part  60  and the supporting bead  74 , to carry out the deformation movements for the opening of the check valve unit  18 , i.e. the deformation movements with which the umbrella edge  34  lifts away from the valve seat  28 , durably and free of sharp-edged actions on the part of the supporting bead and, therefore, in a long-term stable manner. 
         [0089]    The fixing of the insert part  60  of the check valve unit  18  in position is brought about by an insert part receptacle which is designated as a whole as  80  and has an insert part support element  82  with a passage  84 , through which the holding sleeve  62  of the insert part  60  can be pushed so that locking noses  86  of the insert part, which are integrally formed on the holding sleeve  62 , engage behind the insert part support element on a side located opposite the valve element  30  and, therefore, secure the insert part  60  against any release from the insert part support element  82 . 
         [0090]    In this respect, the holding sleeve  62  can preferably be deformed radially inwards with its end area supporting the locking noses  86  so that during the insertion of the insert part  60  into the insert part support element  82  the locking noses  86  abut on the passage  84  with inclined slide-in surfaces  88  and this presses the locking noses  86  radially inwards on account of the action of the inclined slide-in surfaces  88  so that they can be moved through the passage  84  and abut and are supported with their holding surfaces  90  on the insert part support element  82  around the passage  84 . 
         [0091]    In order to move the valve element  30  between the closed position illustrated in  FIG. 2  and an open position, the insert part  60  can be moved relative to the insert part receptacle  80  in a guided manner, for example due to the fact that the holding sleeve  62  can be moved in its longitudinal direction relative to the insert part support element  82  to such an extent in the direction of movement B that the holding surfaces  90  do not abut on the insert part support element  82  until the insert part  60  has been moved with the valve element  30  to such an extent in the direction of the valve seat  28  that the umbrella edge  34  is at a distance from the valve seat  28  when the valve member  32  is not deformed and, therefore, the check valve unit  18  is in the open position. 
         [0092]    The insert part support element  82  preferably comprises openings  92 , through which oil collecting over the base  22  can enter the valve seat support  24  through the insert part support element  82  and flow in the direction of the valve member  32  which, with a sufficiently large amount of oil, therefore generates a sufficiently large static pressure which counteracts, for example, a difference in pressure between the pressure in the chamber and the pressure in the valve seat support when the engine is running which keeps the valve element  30  in the closed position and so the valve member  32  lifts away from the valve seat  28  with the umbrella edge  34  and transfers into the open position in order to allow the oil to exit from an interior space  94  of the valve seat support  24  following the direction of gravity into a chamber R which surrounds the valve member  32  on its convex outer side  38 , wherein the chamber R can be, for example, a chamber of the crankcase or a camshaft chamber. 
         [0093]    In the first embodiment, the base  22 , the valve seat support  24  integrally formed thereon in one piece and the insert part receptacle  80  are, in particular, formed in one piece from a plastic material which is filled with fibers to increase the stability. 
         [0094]    The problem with such a plastic material is to accommodate the valve element  30 , which is produced from an elastomeric material, in a burr-free receptacle such that the valve element  30  can permanently function free from damage. 
         [0095]    For this reason, the insert part  60  is provided which is preferably produced from a plastic material without any fiber filling, wherein the matrix material can, for example, be the same material as the matrix material of the base  22  of the oil collecting device  16  and also of the valve seat support  24  as well as the insert part receptacle  80 . 
         [0096]    The insert part  60  can be produced separately from the oil collecting device  16  as an additional part and be provided with surfaces for accommodating the holding attachment  50  which have a surface form necessary for the wear-free accommodation of elastomeric material and a high surface quality so that the holding attachment  50  and, therefore, also the valve element  30  do not experience any damage whatsoever caused by the surfaces of the insert part  60  during the course of their operation. 
         [0097]    On the other hand, the insert part  60  is robust with respect to its fixing in position in the insert part receptacle  80  and so the insert part receptacle  80  can have the surface problems occurring in conjunction with a fiber-filled plastic material which do not have a negative affect on the connection between the insert part receptacle  80  and the insert part  60 . 
         [0098]    In a second embodiment of an oil separator unit  10 ′ according to the invention with a drainage system  14 ′, illustrated in  FIG. 3 , the insert part  60 ′ is designed in two parts, namely, on the one hand, as a holding sleeve  62 ′ which forms a base member  63  for the valve element  30 ′ which is integrally formed on the base member  63 , for example is sprayed onto it, and penetrates passages  65  provided in the base member  63  so that the valve member  32 ′ of the valve element is connected to the base member  63  in a mechanically fixed manner and, as for the rest, is also terminated with it so as to be sealed against any media. 
         [0099]    As for the rest, the valve member  32 ′ likewise extends like an umbrella as far as the umbrella edge  34  which can abut on the valve seat  28  in the closed position. 
         [0100]    In contrast to the first embodiment, the valve seat  28  is arranged on a flange member  67  of the insert part  60  which is securely connected, for its part, to a guide sleeve  69  for the holding sleeve  62 ′ so that the holding sleeve  62 ′ can be moved in the guide sleeve  69  in a direction of movement B in a limited manner in order to move the valve member  32 ′ from the closed position illustrated in  FIG. 3  into the open position which is determined by holding surfaces  90  of the locking noses  86  which abut on the guide sleeve  69  in the open position. 
         [0101]    The guide sleeve  69  forms a canting-free longitudinal guide for the holding sleeve  62 ′ in the direction of movement B, by means of which the valve member  32 ′ can be moved between the closed position and the open position in a secure and interruption-free manner. 
         [0102]    The flange member  67  preferably abuts on the end side  26 ′ of the valve seat support  24 ′ and terminates sealingly with it which can be realized, for example, by way of a materially locking connection. 
         [0103]    With the second embodiment, as well, the advantage is to be seen in the fact that the insert part  60 ′ including the holding sleeve  62 ′ and the flange member  67  with the guide member  69  is a component which can be produced separately and fixed in place on the valve housing  20  and with which the connection of the valve member  32 ′ to the base member  63  of the holding sleeve  62 ′ can be formed in a wear-free manner and, as for the rest, movability of the holding sleeve  62 ′ relative to the guide sleeve  69  can be ensured in a wear-free manner and so the service life of the valve member  32 ′ produced from the elastomeric material is not limited by surface defects of the material of the valve housing  20 . 
         [0104]    In a third embodiment of an oil separator unit  10 ″ according to the invention with a drainage system  14 ″, illustrated in  FIG. 4 , the valve seat support  24 ″, which forms on one side the valve seat  28 ′ which is arranged facing the valve element  30 ″, is likewise integrally formed on the base  22 . 
         [0105]    The valve element  30 ″ likewise comprises a valve member  32 ″ which is of an umbrella-like design and abuts with its umbrella edge  34  on the valve seat  28 ″ in the closed state of the check valve unit  18 ″. 
         [0106]    The holding attachment  50 ″ is integrally formed on the central area  36  of the valve member  32 ″, namely in this case on a side facing away from the valve seat  28 ″. The holding attachment  50 ″ has a narrowed area  102  which adjoins the valve member  32 ″ and a thickened area  104  which follows on from the narrowed area  102  and is located opposite the valve member  32 ″, these two areas together forming the holding pin  52 ″. 
         [0107]    In this embodiment, as well, the holding pin  52 ″ and the valve member  32 ″ are connected to one another in one piece and produced from an elastomeric material. 
         [0108]    The valve element  30 ″ is fixed in place by an insert part  60 ″ which is arranged on a side of the valve member  32 ″ located opposite the valve seat  28 ″ and keeps the valve element  30  fixed in position with a ring member  106  which engages in the narrowed area  102 , wherein the ring member  106  abuts on the holding pin  52 ″ in the region of the narrowed area  102  with a rounded ring inner side  108 , which has the required surface quality, and, therefore, keeps it limitedly movable in the direction of movement B prior to assembly of the insert part  60 ″. 
         [0109]    The ring member  106  of the insert part  60 ″ is connected to an outer holding ring  112  via arms  110  so that openings  114  result between the arms  110 , through which oil can pass through the insert part  60 ″. 
         [0110]    The insert part  60 ″ has on the outer holding ring  112  projections  116  which engage in recesses  118  of the insert part receptacle  80 ″, wherein in this case the insert part receptacle  80 ″ is integrally formed on the base  22  in one piece and is designed as a sleeve which rises above the valve seat  28 ″ and in the interior space  120  of which the valve member  32 ″ and the insert part  60 ″ can be arranged, wherein the valve member  32 ″ is located in this embodiment between the valve seat  28 ″ and the insert part  60 ″. The movability of the valve member  32 ″ between the closed position, illustrated in  FIG. 4 , and the open position in the direction of movement B is predetermined by the distance of the insert part  60 ″ from the valve seat  28 ″ which is selected such that the valve member can be brought from the closed position, in which the umbrella edge  34  abuts on the valve seat  28 , into the open position, in which the valve member  32 ″ abuts on the insert part  60 ″ with the outer side  38 . 
         [0111]    As a result, the valve member  32 ″ is secured by the insert part  60 ″, in addition, against any detachment from the holding attachment  50 ″ so that even in the case of any detachment from the holding attachment  50 ″ the valve member  32 ″ does not have the possibility of moving through the openings  114 . 
         [0112]    On the contrary, the valve member  32  will be held in the interior space  20  between the valve seat  28 ″ and the insert part  60 ″ even in the case of any detachment of partial sections from the holding attachment  50 . 
         [0113]    As a result, an additional securement for the valve member  32 ″ against any disconnection and being carried along with the oil is provided in this embodiment of the drainage system  14 ″ according to the invention. 
         [0114]    In this embodiment, as well, the surfaces of the ring member  106 , in particular the ring inner sides  108 , may be produced with the surface form and the high surface quality required for the wear-free accommodation of elastomer since the insert part  60 ″ can be produced separately from the base  22  and the insert part receptacle  80 ″ while the surfaces for accommodating the insert part  60 ″ can also be produced with an inferior surface quality. 
         [0115]    As for the rest, those elements of the second embodiment which are identical to those of the first embodiment are given the same reference numerals and so with respect to the description thereof reference can be made in full to the comments on the first embodiment. 
         [0116]    In a fourth embodiment, illustrated in  FIG. 5 , the base  22  is provided with a pot-like recess  130  which has side walls  132  integrally formed on the base  22  in one piece and a base  134 , wherein the base  134  is provided with openings  136  for oil which collects in the pot-like recess  130 . 
         [0117]    The valve element  30 ′″ is inserted into an interior space  138  of the recess  130  and is held by an insert part  60 ′″ likewise inserted into the interior space  138 . 
         [0118]    The insert part  60 ′″ is, in this embodiment, also of a pot-like design and likewise comprises side walls  142  as well as a base  144  which forms, for its part, a ring member  146  which abuts on the holding attachment  50 ′″ of the valve element  30 ′″ with a ring inner side  148 , wherein the holding attachment  50 ′″ extends at least partially through the ring member  146  with a neck  150  and the neck  150  has on its side located opposite the valve member  32 ′″ a thickened area  152  which secures the holding attachment  50 ′″ against any movement through the ring member  146  in the direction of movement B and, in particular, against any movement of the holding attachment  50 ′″ in the direction of the side of the base  14 , on which the valve member  32  is arranged. 
         [0119]    Moreover, the ring inner side  148  has, in the direction of movement B, an adequately large guiding length in order to guide the neck  150  and, therefore, also the valve member  32 ″ during its movements in the direction of movement B in a canting-free manner and, therefore, ensure a reliable functioning of the valve. 
         [0120]    As a result, the valve member  32  of this embodiment is also located between the base  144  of the insert part  60 ′″ and the base  134  of the recess  130  and is, therefore, secured even during any detachment from the holding attachment  50 ′″. 
         [0121]    In order to allow oil to pass through the base  144 , this is provided with openings  154  which are arranged around the ring member  146  and located within the valve seat  28 ′″ which is formed on a side of the base  144  facing the base  134  and extends around the openings  154  so that the valve member  32 ′″ is in a position to prevent any flow of oil through the openings  154  in the closed position with an umbrella edge  34  abutting on the valve seat  28 ′″, but, proceeding from this position, to move into the open position, in which the valve member  32 ′″ abuts on the base  134  and releases the flow of oil. 
         [0122]    The insert part  60 ′″ is fixed in position in the insert part receptacle  80 ″ designed as recess  130 , for example, by way of adhesion of flange sections  156  in flange receptacles  158 , which accommodate the flange sections  156  and are integrally formed on the base  22 , by means of an adhesive layer  160 . As a result, the insert part  60 ′″ is located in the insert part receptacle  80 ′″ in a sealed manner relative to the base  22  and the oil collecting over the base  22  enters the insert part  60 ′″ and passes through the openings  154  in the base  144  thereof when the valve member  32 ′″ is open so that the oil can then flow past the valve member  32 ′″ and can exit from the insert part receptacle  80 ′″ again through the openings  136  in the base  134 . 
         [0123]    A fifth embodiment, illustrated in  FIG. 6 , is designed in the same way as the fourth embodiment, with the single difference that the insert part  60 ′″ is not fixed in position in the insert part receptacle  80 ′″ by way of adhesion of the flange sections  156  to the flange receptacles  158  but rather by way of welding thereof and so a weld seam  162  is formed which represents a sealed closure between the flange section  156  and the flange receptacle  158 . 
         [0124]    As for the rest, those parts which are identical to the corresponding parts of the fourth embodiment are given the same reference numerals and so reference can be made in full to the comments on the third embodiment with respect to the description thereof. 
         [0125]    In a sixth embodiment, illustrated in  FIG. 7 , the insert part  60 ′″ and the insert part receptacle  80 ′″ are designed in a similar way to the fourth and fifth embodiments. 
         [0126]    One difference to the fourth and fifth embodiments consists in the fact that the flange sections  156 ′ engage in circumferential, ring-shaped recesses of the insert part receptacle  80 ′″, designed as flange receptacle  158 ′, and, therefore, can be locked in the insert part receptacle  80 ′″ in a form locking manner. 
         [0127]    In order to be able to reliably provide a sealed closure in the insert part  60 ′″ and the insert part receptacle  80 ′″, a sealing ring  164  is provided in the region of the flange receptacle  158 ′ and this brings about a sealed closure between the side walls  132  of the insert part receptacle  80 ′″ and the side walls  142  of the insert part  60 ′″ when the flange sections  156 ′ are locked into the flange receptacle  158 ′. 
         [0128]    Moreover, the holding attachment  50 ′″ of the sixth embodiment is provided only with the neck  150  which is guided through the ring inner side  148  of the ring member  146  in a canting-free manner, wherein the thickened area  152  serving as securement against loss is missing. 
         [0129]    The securement against loss for the valve element  30 ′″ is brought about by the base  134  of the insert part receptacle  80 ′″. 
         [0130]    As for the rest, those parts of the sixth embodiment which are identical to those of the fourth and fifth embodiments are given the same reference numerals and so with respect to their description reference can be made in full to the third and fourth embodiments as well as the remaining, preceding embodiments. 
         [0131]    In a seventh embodiment, illustrated in  FIG. 8 , the insert part  60 ″″ is provided with an outer flange section  156 ″ which is connected to a flange receptacle  158 ″ of the insert part receptacle  80 ″″ by friction welding, wherein during the friction welding a friction welding area  162 ″ is formed which brings about a fluid-tight, in particular oil-tight connection between the flange section  156 ″ and the flange receptacle  158 ″. 
         [0132]    In this respect, the flange receptacle  158 ″ is provided, for example, with a circumferential groove  172 , in which a ring-shaped projection  174  of the flange section  156 ″ engages. 
         [0133]    In order to achieve an advantageous centering of the insert part  60 ″″ when the flange section  156 ″ is placed on the flange receptacle  158 ″, the insert part  60 ″″ is preferably provided with ribs  176  which rise from the base  144  of the insert part  60 ″″ and engage in the flange receptacle  158 ″, wherein the ribs  176  have, for example, outer edges  178  which can be supported on an inner contour  182  of the flange receptacle  158 ″ for the purpose of centering the insert part  60 ″″. 
         [0134]    The ribs  176  are preferably arranged between the openings  154  on the base  144  and extend as far as the ring member  146  which forms the ring inner side  148  for accommodating the neck  150 ″″ of the valve element  30 ″″. 
         [0135]    In the same way as in the second to sixth embodiments, the neck  150 ″″ preferably has the thickened area  152  for supporting the same on the ring member  146 . 
         [0136]    In addition, the neck  150 ″″ is provided with a cavity  184  which extends into the neck  150 ″″ from a side within the central area  36  of the valve member  32  facing away from the base  144  and serves the purpose of accommodating an assembly pin for the assembly of the valve element  30 ″″. 
         [0137]    As for the rest, the valve element  30 ″″ is movable in direction  70  in the same way as that explained in conjunction with the preceding embodiments. 
         [0138]    As for the rest, those parts of the seventh embodiment which are identical to the parts of the preceding embodiments are given the same reference numerals and so reference can be made in full to the preceding embodiments with respect to the shape and the interaction of these parts with one another as well as the overall functioning of the check valve unit  18 . 
         [0139]    It is, therefore, also possible with the fourth, fifth, sixth and seventh embodiments to produce the insert part  60 ′″,  60 ″″ as a separate part with a suitable surface form and high surface quality, in particular in the region of the ring member  146  holding the holding attachment  50 ′″,  50 ″″ and the ring inner side  148  so that damage to the holding attachment  50 ′″,  50 ″″ of the valve element  30 ′″,  30 ″″ will be avoided and, therefore, a reliable continuous operability of the valve element  30 ′″,  30 ″″ is provided.