Abstract:
The invention relates to a parallel crank drive ( 10 ), particularly for an internal combustion engine ( 11 ) having variable compression ratio, having: a first and a second clutch body ( 20, 21 ) that can each be connected to a first or second shaft ( 14, 19 ); —at least one clutch element ( 22 ) rotatably supported on both clutch bodies; —a housing ( 23 ) encompassing the clutch bodies and clutch elements. The invention further relates to an internal combustion engine having variable compression ratio, having: a pivotally supported crankshaft ( 14 ); —drive shaft ( 19 ); —parallel crank drive ( 10 ) between the crankshaft and drive shaft; —a housing ( 23 ) encompassing the parallel crank drive. The invention further relates to a manual transmission, particularly for an internal combustion engine ( 11 ) having variable compression ratio, having: an input shaft ( 19 ) that can be connected to a pivotally supported crankshaft ( 14 ); the parallel crank drive ( 10 ) between the crankshaft and input shaft.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is the U.S. national phase of PCT/EP2007/011476 filed Dec. 31, 2007, the entirety of which is incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention pertains to a parallel crank drive, particularly to a parallel crank drive for an internal combustion engine with a variable compression ratio, to an internal combustion engine with a variable compression ratio and to a manual transmission, particularly to a manual transmission for an internal combustion engine with a variable compression ratio. 
       BACKGROUND OF THE INVENTION 
       [0003]    EP 1 082 548 B1 describes a parallel crank drive that is referred to as a clutch element and designed for an internal combustion engine with a displaceable crankshaft in order to vary the compression ratio, wherein this parallel crank drive features a first and a second clutch body that are referred to as rotary bodies and coupling elements that are referred to as crank elements. The rotary bodies can be respectively connected to a first and a second shaft. The respective crank elements are rotatably supported on both rotary bodies. In this known clutch element, the two rotary bodies are aligned in parallel planes of rotation and can be respectively connected to the mutually assigned shaft ends of the crankshaft and the output shaft. The crankshaft and the output shaft are arranged one behind the other in an axially parallel fashion with an eccentricity, and the crank elements that connect both rotary bodies have a crank radius that corresponds to the eccentricity and are spaced apart from one another in the circumferential direction. The second rotary body that is connected to the output shaft features two partial bodies that are rigidly connected to one another and referred to as disk elements, wherein the first rotary body that is connected to the crank shaft and also realized in a disk-shaped fashion is arranged between said partial bodies. The two disk elements are rigidly connected to one another on their outer edges by means of screws. The crank elements are supported on the first rotary body and the two disk elements of the second rotary body by means of rolling bearings or even sliding bearings. Due to this housing-like design of the second rotary body, the interior space defined by the two disk elements is realized in the form of an oil chamber that is connected to the engine oil circuit. During operation, this space is filled across the entire circumference under the influence of centrifugal force such that oil is supplied through lubricating channels assigned to the individual bearings of the crank elements. 
         [0004]    This known parallel crank drive has the disadvantage that the oil remains in the interior space of the second rotary body up to almost the center of the crankshaft and therefore generates correspondingly high friction during the operation. 
       SUMMARY OF THE INVENTION 
       [0005]    The invention is based on the objective of developing a parallel crank drive that features lower frictional losses. 
         [0006]    This objective is attained with a parallel crank drive according to claim  1  or according to claim  9  or according to claim  11 . Other embodiments are described in the dependent claims. 
         [0007]    The invention proposes a parallel crank drive, particularly for an internal combustion with variable compression ratio, featuring a first and a second clutch body that can be connected to a first and a second shaft, respectively, at least one coupling element that is rotatably supported on both clutch bodies, and a housing that encloses the clutch bodies and the coupling element. 
         [0008]    The housing makes it possible, for example, to modify the above-described parallel crank drive according to EP 1 082 548 B1, the full disclosure of which is incorporated herein by reference, in such a way that the known closed, housing-like design of the second clutch body is replaced with an open design. Starting with the known closed, housing-like design, this open design can be achieved in that the first disk element or partial body situated near the second shaft and/or the second disk element or partial body situated near the first shaft features at least one opening. The oil can exit the interior space defined by the two disk elements through this opening. The openings are preferably arranged in the end faces and/or circumferential surfaces of the disk elements. The openings furthermore result in a reduction of the mass and of the moment of inertia of the second clutch body and of the parallel crank drive. In addition, the recessed bores for the clutch elements in the two disk elements can now be realized in the form of through-bores, wherein this represents a significant simplification in comparison with the blind bores provided in known disk elements for tightness reasons. Furthermore, a seal is no longer required between the two disk elements. The housing also makes it possible, for example, to modify the above-described parallel crank drive known from EP 1 082 548 B1 in such a way that the known two-part design of the second clutch body featuring the two disk elements is replaced with a one-part design, in which the second disk element situated near the first shaft is eliminated. 
         [0009]    The housing may be realized in any required fashion. For example, it may be formed by a crankcase of the internal combustion engine or a transmission case of a manual transmission. In this case, the parallel crank drive consequently is situated in the interior of the crankcase or transmission case. However, the housing may also be formed by a wall of a crankcase of an internal combustion engine or a wall of a transmission case of a manual transmission and by a cover that is connected to the wall. In this case, it would be possible, for example, to realize the cover integrally with the wall or to screw the cover to the wall. 
         [0010]    It would be possible to support the second clutch body on the housing in the region of the first shaft and/or in the region of the second shaft. This may be realized, for example, with the aid of sliding bearings and/or rolling bearings. The bearings preferably consist of single-row or double-row bearings. The two-sided support, i.e., the support in the region of the first shaft and in the region of the second shaft, is preferably utilized if the parallel crank drive is realized in the form of a dual mass flywheel, in which the first and the second clutch body respectively form the primary flywheel mass and the secondary flywheel mass of the dual mass flywheel. 
         [0011]    It would be possible to provide a seal relative to the first shaft, preferably with the aid of a rotary shaft seal, and to provide the coupling element with a lifetime grease filling. The rotary shaft seal prevents oil from being admitted into the parallel crank drive from the main bearing of the first shaft that lies closest to the parallel crank drive. The lubrication of the coupling element bearings with such oil is also unnecessary due to the lifetime grease filling. In this case, the housing that encloses the clutch bodies and coupling elements may also be completely eliminated. 
         [0012]    It would be possible to provide the housing with at least one oil drain opening. The oil drain opening is preferably connected to an oil pan of an internal combustion engine or to a transmission case of a manual transmission. 
         [0013]    The invention furthermore proposes a parallel crank drive, particularly for an internal combustion with variable compression ratio, featuring a first and a second clutch body that can be connected to a first and a second shaft, respectively, at least one coupling element that is rotatably supported on both clutch bodies, and an oil collector that completely encloses the clutch bodies in the circumferential direction. 
         [0014]    Analogous to the above-described housing, this oil collector makes it possible, for example, to realize the above-described open design of the second clutch body featuring the two disk elements and the above-described one-part design of the second clutch body, in which the second disk element is eliminated. 
         [0015]    The oil collector is preferably sealed relative to the clutch bodies by means of a labyrinth and/or by means of slip rings. 
         [0016]    The invention furthermore proposes a parallel crank drive, particularly for an internal combustion engine with variable compression ratio, featuring a first and a second clutch body that can be connected to a first and a second shaft, respectively, at least one coupling element that is rotatably supported on both clutch bodies, and an oil collector that partially encloses the clutch bodies in the circumferential direction, wherein the first and/or the second clutch body feature(s) at least one oil outlet opening, and wherein a closing device for the oil outlet opening is provided and realized in such a way that the oil outlet opening is opened when it sweeps over the oil collector and is otherwise closed. 
         [0017]    Analogous to the above-described housing and the above-described oil collector, this oil collector makes it possible to realize, for example, the above-described open design of the second clutch body featuring the two disk elements and the above-described one-part design of the second clutch body, in which the second disk element is eliminated. 
         [0018]    The oil collector may be arranged in any required position in the circumferential direction. It is preferably arranged underneath the two clutch bodies. In this case, the oil collector is also able to collect the oil flowing out of the oil outlet opening while the clutch bodies are at a standstill. 
         [0019]    Each of the proposed oil collectors may feature at least one oil drain opening. The oil drain opening is preferably connected to an oil pan of an internal combustion engine or to a transmission case of a manual transmission. 
         [0020]    In each of the proposed parallel crank drives, at least one oil supply channel may extend up to the coupling element in the first shaft and the first clutch body. The oil supply channel may be connected, for example, to the oil supply for a bearing of the first shaft such that the oil reaches the coupling element and its bearings in the two clutch bodies directly through this oil supply channel. 
         [0021]    In each of the proposed parallel crank drives, the first and/or the second clutch body may feature at least one opening. This opening was already described in greater detail above. 
         [0022]    In each of the proposed parallel crank drives, the second clutch body may feature a first partial body situated near the first shaft and a second partial body situated near the second shaft that are mounted one on the other with at least one mounting element, wherein this mounting element extends between the surfaces of the partial bodies that face one another and its radial distance from the second shaft is smaller or equal to the radial distance of at least one coupling element from the second shaft, and wherein the first clutch body is arranged between the partial bodies and features at least one opening through which the mounting element protrudes. The two partial bodies may be shaped as required and are preferably realized in a disk-shaped fashion. The second clutch body featuring the two partial bodies is also realized in two parts, wherein this two-part design was already described in greater detail above. In contrast to the above-described two-part design according to EP 1 082 548 B1 in which the two disk elements or partial bodies are rigidly connected to one another at their outer edges with the aid of screws, the two partial bodies of the proposed second clutch body are mounted one on the other at locations that lie farther radially inward with the aid of mounting elements. Consequently, the outside diameter of the proposed partial bodies can be significantly reduced in comparison with these known disk elements such that the mass and the moment of inertia of the second clutch body and of the parallel crank drive are reduced accordingly. 
         [0023]    Each of the proposed parallel crank drives may be realized in the form of a flywheel, preferably a dual mass flywheel. The first and the second clutch body preferably form the primary flywheel mass and the secondary flywheel mass of the dual mass flywheel. 
         [0024]    The invention furthermore proposes an internal combustion engine with variable compression ratio featuring a pivotably supported crankshaft, an output shaft and one of the proposed parallel crank drives between the crankshaft and the output shaft. 
         [0025]    The invention also proposes an internal combustion engine with variable compression ratio featuring a pivotably supported crankshaft, an output shaft, a parallel crank drive between the crankshaft and the output shaft and a housing that encloses the parallel crank drive. 
         [0026]    In each of the proposed internal combustion engines, the housing may be formed by a crankcase of the internal combustion engine. 
         [0027]    In each of the proposed internal combustion engines, the housing may be formed by a wall of a crankcase of the internal combustion engine and a cover that is connected to the wall. In this case, it would be possible, for example, to realize the cover integrally with the wall or to screw the cover to the wall. 
         [0028]    In each of the proposed internal combustion engines, the parallel crank drive may feature a first and a second clutch body that are connected to the crankshaft and the output shaft, respectively, and at least one coupling element that is rotatably supported on both clutch bodies. The crank radius of the coupling element can be, for example, at a right angle to the two shafts. 
         [0029]    In each of the proposed internal combustion engines, the parallel crank drive may be realized in the form of a flywheel, preferably a dual mass flywheel. 
         [0030]    In each of the proposed internal combustion engines, a flywheel, preferably a dual mass flywheel, may be incorporated between the parallel crank drive and the output shaft. 
         [0031]    In each of the proposed internal combustion engines, the housing may feature at least one oil drain opening that is connected to an oil pan of the internal combustion engine. 
         [0032]    The invention furthermore proposes a manual transmission, particularly for an internal combustion engine with variable compression ratio, featuring an input shaft that can be connected to a pivotably supported crankshaft and one of the proposed parallel crank drives between the crankshaft and the input shaft. 
         [0033]    The invention also proposes a manual transmission, particularly for an internal combustion engine with variable compression ratio, featuring an input shaft that can be connected to a pivotably supported crankshaft, a parallel crank drive between the crankshaft and the input shaft and a housing that encloses the parallel crank drive. 
         [0034]    The preceding explanations regarding the proposed parallel crank drives and internal combustion engines also apply accordingly to the proposed manual transmissions. 
         [0035]    In each of the proposed manual transmissions, the housing may be formed by a transmission case of the manual transmission. 
         [0036]    In each of the proposed manual transmissions, the housing may be formed by a wall of a transmission case of the manual transmission and a cover that is connected to the wall. In this case, the cover may, for example, be realized integrally with the wall or screwed to the wall. 
         [0037]    In each of the proposed manual transmissions, the parallel crank drive may feature a first clutch body that can be connected to the crankshaft, a second clutch body that can be connected to the input shaft and at least one coupling element that is rotatably supported on both clutch bodies. The crank radius of the coupling element may be, for example, at a right angle to the shafts. 
         [0038]    In each of the proposed manual transmissions, the parallel crank drive may be realized in the form of a flywheel, preferably a dual mass flywheel. 
         [0039]    In each of the proposed manual transmissions, a flywheel, preferably a dual mass flywheel, may be incorporated between the crankshaft and the parallel crank drive. 
         [0040]    In each of the proposed manual transmissions, a starting clutch may be provided between the crankshaft and the parallel crank drive or between the parallel crank drive and the input shaft. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0041]    Other advantageous embodiments of the invention are described in greater detail below with reference to the drawings. However, the individual characteristics shown are not restricted to the respective embodiments, but can also be combined with other individual characteristics described above or with individual characteristics of other embodiments such that additional embodiments are formed. The details in the drawings should merely be interpreted in an explanatory, but not in a restrictive sense. Shown are: 
           [0042]      FIG. 1 , a longitudinal section through a first embodiment of a parallel crank drive for an internal combustion engine with variable compression ratio, 
           [0043]      FIG. 2 , a longitudinal section through a second embodiment of a parallel crank drive for an internal combustion engine with variable compression ratio, 
           [0044]      FIG. 3 , a longitudinal section through a third embodiment of a parallel crank drive for an internal combustion engine with variable compression ratio, 
           [0045]      FIG. 4 , a schematic cross section of  FIG. 3 , 
           [0046]      FIG. 5 , a longitudinal section through a fourth embodiment of a parallel crank drive for an internal combustion engine with variable compression ratio, and 
           [0047]      FIG. 6 , a schematic cross section of  FIG. 5 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0048]      FIG. 1  shows a first embodiment of a parallel crank drive  10  that is, for example, attached to an internal combustion engine  11  with variable compression ratio. The internal combustion engine  11  is only partially illustrated and features a crankcase  12  of which only a wall  13  on the transmission side is shown, a crankshaft  14  and eccentric collars of which only an eccentric collar  15  on the transmission side is shown. The crankshaft  14  that extends farther toward the left in  FIG. 1  is merely illustrated in the form of the right end on the transmission side with the shaft journal  16  on the transmission side and the web  17  on the transmission side situated adjacent thereto on the left. The shaft journal  16  is eccentrically supported in the eccentric collar  15  that is supported, in turn, in the wall  13 . The other not-shown shaft journals are supported in the other not-shown eccentric collars in the same fashion, and said eccentric collars are supported at not-shown locations in the crankcase  12  in the same fashion. The crankshaft axis  18  defined by the shaft journals  16  can be conventionally pivoted relative to the crankcase  12  about the output shaft axis  19  of a not-shown output shaft that is stationary relative to the crankcase  12  and defined by the eccentric collars  15 . Consequently, a detailed description is not provided at this point and we refer, for example, to the explanations in EP 1 082 548 B1 in this context. Although the crankshaft axis  18  and the output shaft axis  19  are not visible in  FIGS. 1 to 4  and  5  because they overlap one another in these illustrations, their position is illustrated quite well in  FIGS. 4 and 6 . 
         [0049]    In this case, the parallel crank drive  10  features a first clutch body  20 , a second clutch body  21 , six coupling elements  22  that are illustrated quite well in  FIGS. 4 and 6 , but of which only one is visible in  FIG. 1 , and a housing  23 . The first clutch body  20  is realized in a disk-shaped fashion and rigidly connected at a central flange region to a flange of the crankshaft  14  that forms the end of the crankshaft  14  on the transmission side and continues the shaft journal  16  toward the right in  FIG. 1 . The second clutch body  21  is also realized in a disk-shaped fashion, however, in the form of a hollow disk that is open toward the crankshaft  14 , i.e., toward the left in  FIG. 1 , and in the interior of which the first clutch body  20  is situated. It can be rigidly connected to a flange region of the not-shown output shaft with a central flange region. In this case, the hollow disk shape of the second clutch body  21  is achieved in that it features a first partial body  24  that lies near the crankshaft  14 , i.e., on the left in  FIG. 1 , and is essentially realized in the form of a circular ring and a second partial body  25  that lies near the output shaft, i.e., on the right in  FIG. 1 , and is essentially realized in a disk-shaped fashion. The outer edges of both partial bodies  24 ,  25  are axially bent toward one another and connected with the aid of circumferentially distributed screws. 
         [0050]    The coupling elements  22  consist of cranks in this case, but may also be realized differently, for example, with the aid of gears. Each coupling element  22  features a cylindrical center disk  26  and a pin  27  that is arranged eccentric and axially parallel thereto, wherein the pin has a smaller diameter than the center disk  26  and protrudes from both end faces of the center disk  26 . The center disk axis  28  of the center disk  26  and the pin axis  29  of the pin  27  extend parallel to the crankshaft axis  18  and the output shaft axis  18  and have an eccentricity, i.e., a distance between one another that is identical to the eccentricity of the crankshaft axis  18  and the output shaft axis  19 . This is illustrated quite well in  FIGS. 4 and 6 . The center disk  26  is supported in the first clutch body  20  and the parts of the pin  27  that protrude toward the left and the right from the center disk  26  in  FIG. 1  are supported in the first and the second partial body  24 ,  25 . The corresponding bearing bores in the two partial bodies  24 ,  25  are realized in the form of through-bores in this case. An oil supply channel  30  extends in the crankshaft  14  from the bearing surface of the shaft journal  16  to the end face of the crankshaft flange and then radially outward through the first clutch body  20  via the adjoining end face of its flange part, namely up to the coupling element  22  or, more specifically, up to the center disk  26 . Consequently, lubricating oil being supplied to the shaft journal  16  can be routed to the center disk  26  through the oil supply channel  30  and from there to the protruding parts of the pin  27  that are supported in the through-bores. The two partial bodies  24 ,  25  feature not-shown openings through which the oil emerging from the bearing surfaces of the coupling element  22  can flow out of the interior of the second clutch body  21 . 
         [0051]    In this case, the housing  23  is formed by the wall  13  and a cover  31  that is connected to the wall  13  with the aid of screws. The second clutch body  21  is supported on the housing  23  in the region of the crankshaft  14  and in the region of the output shaft. For this purpose, the inner edge of the first partial body  24  with the shape of a circular ring is supported radially inward on an axial collar of the wall  13  in the region of the shaft journal  16  with the aid of a first roller bearing  32  and the central flange region of the second partial body  25  is supported radially outward on an inner circumferential surface of a central through-opening of the cover  31  with the aid of a second roller bearing  33 . The second clutch body  21  is supported on both sides of the first clutch body  20  and therefore is secured against tilting. A ring seal  34  that prevents oil from leaking out of the housing  23  of the parallel crank drive  10  is provided on the transmission side of the second roller bearing  33  that faces away from the crankshaft  14 , i.e., on the right side of the second roller bearing in  FIG. 1 . 
         [0052]    In its not-shown bottom region, the cover  31  features a not-shown oil drain opening that is connected to a not-shown oil pan of the internal combustion engine  11 . Consequently, the oil collected by the housing  23  can be routed back to the oil pan through the oil drain opening. 
         [0053]      FIG. 2  shows a second embodiment of a parallel crank drive  10  that is realized similar to the first embodiment such that only the differences between the two embodiments are described in detail below. In this second embodiment, the two partial bodies  24 ,  25  are connected to one another farther radially inward rather than at their outer edges as in the first embodiment. This is achieved with several mounting elements  35 , of which only one is illustrated. The radial distances of the mounting elements  35  from the output shaft and the output shaft axis  19  is smaller than the radial distance of the coupling element  22  from the output shaft and the output shaft axis  19  in this case, i.e., the mounting elements  35  lie radially within the coupling elements  22 . In addition, the two partial bodies  24 ,  25  do not extend radially outward any farther than required for the support of the pin  27 . 
         [0054]    Each mounting element  35  features two mutually aligned elevations  36  that protrude axially inward from the facing inner surfaces of the two partial bodies  24 ,  25  and are screwed to one another. In the region of each mounting element  35 , the first clutch body  20  arranged between the partial bodies  24 ,  25  features an opening  37  through which the corresponding mounting element  35  protrudes. The openings  37  are shaped such that they do not impair the relative movement between the two clutch bodies  20 ,  21  during the operation and while the crankshaft  14  is pivoted. 
         [0055]    In addition, a second ring seal  38  is provided radially within the first roller bearing  32  between the collar of the wall  13  and the flange of the crankshaft  14  in this second embodiment. This prevents engine oil from leaking out of the crankcase  12  and into the parallel crank drive  10 . The oil supply channel  30  of the first embodiment is not provided in this case because the lubrication of the coupling elements  22  is realized differently, e.g., due to the fact that they move through a not-shown oil sump, wherein the oil drain opening that is provided in the first embodiment and that is connected to the oil pan is also eliminated in this case. 
         [0056]      FIGS. 3 and 4  show a third embodiment of a parallel crank drive  10  that is realized similar to the first and the second embodiment such that only the differences between these embodiments are described in detail below. In this third embodiment, an oil collector  39  that completely encloses the clutch bodies  20 ,  21  in the circumferential direction is provided instead of the housing  23  of the first and second embodiments. In  FIG. 3 , the wall  13  and the eccentric collar  15  are not illustrated for the sake of clarity. The oil collector features a first and a second central through-opening  40 ,  41  that are arranged in the lateral surface facing the not-shown crankcase, i.e., in the left lateral surface in  FIG. 3 , and in the opposite lateral surface, i.e., in the right lateral surface in the figure, respectively. The first through-opening  40  surrounds the not-shown eccentric collar and the shaft journal  16  and is supported on the not-shown collar of the wall  13  with a not-shown slip ring. The second through-opening  41  surrounds the flange of the second coupling body  21  and is supported on this with a slip ring  42 . The second roller bearing  33  of the first and the second embodiment is eliminated in this case. The two clutch bodies  20 ,  21  are realized in the same fashion as in the second embodiment, but may also be realized in accordance with the first embodiment. An oil drain opening  43  is provided on the bottom of the oil collector  39  and connected to the oil pan. 
         [0057]      FIG. 4  clearly shows that the oil collector  39  completely encloses the clutch bodies  20 ,  21  in the circumferential direction. 
         [0058]      FIGS. 5 and 6  show a fourth embodiment of a parallel crank drive that is realized similar to the third embodiment such that only the differences are described in detail below. In this fourth embodiment, the oil collector  39  does not completely enclose the clutch bodies  20 ,  21  in the circumferential direction as in the third embodiment, but rather only partially. In this case, it is arranged underneath the two clutch bodies  20 ,  21  and, in contrast to the third embodiment, its oil drain opening  43  is offset toward the not-shown crankcase  12 , i.e., toward the left in  FIG. 5 . 
         [0059]    In this fourth embodiment, the second clutch body  21  furthermore features several openings that are distributed over its circumference and that serve as oil outlet openings  44  for the oil collected in the interior of the second clutch body  21  realized in the form of a hollow disk as in the first embodiment. With respect to these oil outlet openings  44 ,  FIG. 5  only shows the lower oil outlet opening and  FIG. 6  only shows the lower five oil outlet openings currently situated in the region of the oil collector  39 . 
         [0060]    A closing device  45  is provided for each oil outlet opening  44  and realized in such a way that the corresponding oil outlet opening  44  is opened when it sweeps over the oil collector  39  and is otherwise closed. For this purpose, it features a valve pin  46  that cooperates with a ridge  47  protruding radially inward from the bottom of the oil collector  39 . The valve pin  46  is seated in the oil outlet opening  44  and its diameter is smaller than that of the oil outlet opening. On the radially inner end, i.e., on the upper end in  FIG. 5 , it features a spherical shut-off element that can tightly adjoin a correspondingly shaped valve seat around the radially inner edge of the oil outlet opening  44 , i.e., the upper edge in  FIG. 5 , as illustrated quite well on the two outer closing devices  45  in  FIG. 6 . During the operation, the valve pins  46  are pressed radially outward by the centrifugal force such that the shut-off elements are pressed against their valve seats. In this case, the valve pins  46  protrude relatively far from the oil outlet openings  44  with their radially outer ends, i.e., with their lower ends in  FIGS. 5 and 6 . However, as soon as a valve pin  46  reaches the region of the oil collector  39 , this outer end comes in contact with the upper edge of the ridge  47  that steadily increases in height relative to the bottom of the oil collector  39  radially inward in the circumferential direction from the edge of the oil collector  39  to the center, where the oil drain opening  43  is situated, and then once again decreases in height radially outward up to the opposite edge of the oil collector  39 . Consequently, the valve pin  46  is steadily pressed radially inward when it approaches the oil drain opening  43  or the center of the oil collector  39  such that the shut-off element is lifted off its valve seat and the oil can flow radially outward through the now opened oil outlet opening  44  and can be collected by the oil collector  39 . The shut-off element is once again lowered onto its valve seat as soon as this closing device  45  moves away from the oil collector  39 .