Abstract:
A machine has a shaft rotatable in at least one lubricated bearing. A lubricant duct for lubricating the bearing extends along the first shaft. A turbine, having blades engaging radially in the lubricant duct and oriented warped to the axis of the first shaft, is situated in the lubricant duct.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority from German Patent Application No. 102010005821.1, filed Jan. 27, 2010, which is incorporated herein by reference in its entirety. 
       TECHNICAL FIELD 
       [0002]    The technical field relates to a machine having a shaft rotatable in at least one lubricated bearing, and in particular the lubricant supply of this bearing. 
       BACKGROUND 
       [0003]    A machine having a shaft rotatable in a lubricated bearing is known from DE 33 20 086 C2, in which a lubricant duct for lubricating the bearing extends axially in the interior of the shaft. In that the lubricant duct is guided along the shaft, lubricant points are also reachable which are difficult to supply in other ways, typically via ducts guided in a housing of the machine. The lubricant duct in the interior of a shaft can be long, however, and its cross-section is narrowly limited, because it cannot weaken the shaft, on the one hand, but the diameter of the shaft is to be as small as possible, on the other hand, so that, both for reasons of cost and also to avoid unnecessary friction losses, the diameter of the bearings receiving the shaft may be kept as smallest possible. It is thus necessary to supply lubricant from a lubricant source at elevated pressure. A pump required for this purpose increases both the costs of the machines and also the breakdown risk. 
         [0004]    In view of the foregoing, at least one object is therefore to specify a machine having a first shaft rotatable in at least one lubricated bearing and a lubricant duct extending along the first shaft for lubricating the bearing, which manages without an external pump for supplying the lubricant at elevated pressure. In addition, other objects, desirable features and characteristics will become apparent from the subsequent summary and detailed description, and the appended claims, taken in conjunction with the accompanying drawings and this background. 
       SUMMARY 
       [0005]    The at least one object is achieved in that, in such a machine, a turbine, having blades engaging radially in the lubricant duct and oriented warped to the axis of the first shaft, is situated in the lubricant duct. Because of their orientation, the blades provide the lubricant circulating in the lubricant duct with an impulse in the axial direction, so that the pressure of the lubricant in the duct is elevated downstream from the turbine and sufficient lubrication of the bearing can be ensured via the duct. 
         [0006]    The turbine is preferably connected rotationally fixed to the shaft. Such a turbine does not require parts rotatable in relation to the shaft on its part and is therefore maintenance-free and nearly indestructible in normal operation of the machine. The lubricant duct can have a widened area on a first end of the shaft, in which the turbine is inserted and in which it is preferably held in a friction-locked or formfitting manner. The turbine can be installed in a conceivably simple manner by insertion in the widened area. The blades of the turbine preferably terminate flush with an end of the shaft, in order to acquire lubricant standing at the end of the shaft and draw it into the lubricant duct. 
         [0007]    The turbine can be implemented in a simple way, in that a plurality of holes oriented warped to the axis are formed in a main body. The blades are each formed by intermediate walls between adjacent holes. In order to avoid an imbalance, the holes are expediently transferable congruently into one another by a rotation around the axis of the turbine. The warped holes may be fused with one another to form a single axial passage. If the warped holes diverge toward an outlet side of the turbine, the centrifugal force acting on lubricant flowing through during the rotation of the turbine can also contribute to the conveyance action of the turbine. 
         [0008]    In order to supply the turbine with lubricant, high pressure is not required at the intake of the turbine or at the end of the first shaft on which the turbine is attached. It is thus possible in particular to feed the turbine via a drop catcher, which is attached on the circumference of a rotating wheel immersed in a lubricant reservoir, in order to collect lubricant spun off of the wheel. 
         [0009]    The machine is preferably a stepped transmission, in particular a shift transmission or a double-clutch transmission for a motor vehicle. 
         [0010]    The rotating wheel immersed in the lubricant reservoir can particularly be a ring gear of a differential in such a transmission. 
         [0011]    The impulse increases achievable using the turbine, it is possible to supply still one or more additional lubrication points downstream from the first shaft via the lubricant duct running through the first shaft. Alternatively, the turbine can also be situated between two lubrication points of a multipart supply line, in order to compensate for pressure losses along the supply line or volume losses on the lubrication point located upstream, and also ensure a sufficient lubricant feed to the lubrication point further located downstream. In particular, bearings of the first and at least one second shaft may be supplied with lubricant, in that a lubricant duct in this second shaft is connected in series to the lubricant duct of the first shaft, the second shaft being able to be situated both upstream and also downstream from the first shaft. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    The embodiments will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements, and: 
           [0013]      FIG. 1  shows a double-clutch transmission in an axial section; 
           [0014]      FIG. 2  shows the double-clutch transmission in a schematic cross-section; 
           [0015]      FIG. 3  shows a detail view of a housing wall of the transmission having a drop catcher fastened on the housing wall; 
           [0016]      FIG. 4  shows a perspective view of a turbine for lubricant oil conveyance; 
           [0017]      FIG. 5  shows a section through the turbine in a plane shifted parallel to the axis of the turbine; and 
           [0018]      FIG. 6  shows a section through the turbine along plane VI-VI from  FIG. 5 . 
       
    
    
     DETAILED DESCRIPTION 
       [0019]    The following detailed description is merely exemplary in nature and is not intended to limit application and uses. Furthermore, there is no intention to be bound by any theory presented in the preceding background or summary or the following detailed description. 
         [0020]      FIG. 1  shows a schematic section through a double-clutch transmission for a motor vehicle. A double clutch  1 , which is known per se, is situated between the output shaft  2  of an engine (not shown) and two input shafts  3 ,  4  of the transmission, which are situated concentrically to one another on the same axis, to alternately apply torque to the input shaft  3  or the input shaft  4 . 
         [0021]    Multiple gearwheels  5 ,  6 ,  7  are installed rotationally fixed on the input shafts  3 ,  4 , which in turn mesh with gearwheels  8  to  11  on two parallel lay shafts  12 ,  13 . The gearwheels  8  to  11  of the lay shafts  12 ,  13  are fixable in a rotationally fixed manner on the lay shafts  12 ,  13  via locking synchronization devices  14  to  17 . A third lay shaft  18  carries gearwheels  19 ,  20 , which mesh with gearwheels  21 ,  22  of the lay shaft  12 . In that, for example, the locking synchronization device  15  couples the gearwheel  22  to the lay shaft  12 , a first gear of the transmission can be implemented by torque transmission between the gearwheels  5 ,  8 ,  21 ,  19 ,  20 ,  22 . 
         [0022]    In order to allow shifting between the gears without torque interruption, the second gear, like all even-numbered gears, is assigned to the hollow input shaft  4 , while the odd-numbered gears are produced via the inner input shaft  3 , which extends through the hollow input shaft  4 . Since the principles of such double-clutch transmissions have been previously published in various forms, they do not need to be explained in detail here. 
         [0023]    Every lay shaft  12 ,  13 ,  18  carries a pinion  23 ,  24 ,  25 , which meshes with a ring gear  26  of a differential  27 . In that a locking synchronization device  28  locks the gearwheels  19 ,  20  on the lay shaft  18 , a reverse gear can be generated via its pinion  25 . 
         [0024]      FIG. 2  illustrates the location of the axes of the differential  27 , the input shafts  3 ,  4 , and the lay shafts  12 ,  13 ,  18  in a housing  29 , which encloses the transmission. Some of the gearwheels of the transmission are shown as circles concentric to the axes in  FIG. 2   
         [0025]    The ring gear  26  of the differential  27  extends furthest down of all gearwheels and is immersed on a part of its circumference in the oil sump  30 . In order to keep splashing losses small, the oil level  31 , which is indicated as a dot-dash line, is set when the transmission is stationary so that the gearwheels of the shafts  3 ,  4 ,  12 ,  13 ,  18  are not immersed and their teeth which mesh with one another are lubricated by oil mist swirled up by the ring gear  26 . When the transmission is running, the oil from the sump  30  is distributed everywhere in the housing  29 . Oil which runs off of the shafts  3 ,  4 ,  12 ,  13  and their gearwheels first reaches a temporary store  34 , which lies somewhat higher than the oil sump  30  in the housing  29  and is separated from the oil sump  30  by an inner wall  32 . A narrow gap  33  at the lower end of the inner wall  32  allows a delayed backflow of the oil into the sump  30 . This has the result that in operation, the oil level of the sump  30  drops to a level  31 ′, which is still sufficient to wet the teeth of the ring gear  26 . The splashing losses of the transmission in continuous operation are thus close to zero. 
         [0026]      FIG. 3  shows a perspective detail view of an inner side of a wall  35  of the housing  29  enclosing the transmission. A roomy recess  36 , which is provided to accommodate a part of the differential  27 , fills up a majority of the lower area of the wall  35 . Recesses  37 ,  38 ,  39  are shown all around the recess  36 , in each case for an end section of the lay shafts  13 ,  12 , or  18 , respectively. While the recesses  37 ,  38  are essentially delimited by ribs  40  protruding from the wall  35 , the recess  39  is indented in the wall  35 , and the end of a hole  41  can be seen on its floor, which extends within the wall  35  to a drop catcher  42 . The drop catcher  42  has a cross-section curved like a horn having an open end  43 , which faces toward the ring gear  26  (not shown in  FIG. 3 ) to catch oil, which the teeth of the ring gear  26  entrain from the oil sump  30  during its rotation and subsequently spin off. The collected oil reaches the recess  39  via the drop catcher  42  and the hole  41  and stands at a front end of the lay shaft  18  there. 
         [0027]    As shown in  FIG. 1 , a duct  44  extends over the entire length of the lay shaft  18 , and spur lines (not shown in  FIG. 1  for the sake of clarity) branching from the duct  44  lead to roller bearings  45 ,  46  adjacent to the ends of the lay shaft  18 , in order to supply them with oil. In order to convey the oil throughput through the duct  44 , a turbine  47  is inserted into a widened area on the end of the lay shaft  18  facing toward the recesses  39 .  FIG. 4 ,  FIG. 5 , and  FIG. 6  show this turbine  47  in a perspective view or in section. 
         [0028]    The turbine  47  is, as shown in  FIG. 4 , a one-piece metal body essentially having the form of a flat cylinder, through which a passage  48  extends in the axial direction. The passage  48  is obtained by multiple drilling or milling steps. Multiple holes  49 , five here, are advanced at uniform angular intervals to one another warped to the axis of symmetry through the body of the turbine  47 ; i.e., each rotation of the turbine  47  by 2π/5 around its axis of symmetry transfers the turbine  47  into itself. The diameter of the holes  49  is selected so that they fuse into a single passage  48 .  FIG. 5  shows a section through the turbine  47  along an axis—identified by  50  here—of such a hole  49 , a second hole  49  may be seen in the section. 
         [0029]      FIG. 6  shows the turbine in section along the plane VI-VI, which is perpendicular to the hole axis  50 , from  FIG. 5 . In this section, walls  51 , which remain between the individual holes  49  and protrude radially inward into the passage  48 , may be seen, which give oil penetrated therein an impulse in the axial direction when the turbine  47  rotates. As also shown in the section of  FIG. 6 , the holes  49  approach closer and closer to the outer circumference of the turbine on the downstream side of the turbine  47 . Therefore, not only the warped orientation of the holes  49  and walls  51 , but rather also the centrifugal force acting in the rotating turbine  47  drive the oil through the turbine  47 . A dynamic pressure can thus be built up downstream from the turbine  47  in the duct  44 , which ensures a sufficient oil supply of the roller bearings  45 ,  46  and additionally also allows the supply of roller bearings of the lay shafts  12 ,  13  and the input shafts  3 ,  4  via lines  52 , which, as shown in  FIG. 1 , connect the downstream end of the duct  44  to ducts  54 ,  55 ,  56  of these shafts in a wall  53  of the transmission housing facing away from the double clutch  1  and the differential  27 . 
         [0030]    To increase the oil pressure in the ducts  54 ,  55 ,  56 , the shafts  3 ,  12 ,  13  may also be provided with turbines  47  on the input side, i.e., on their end facing away from the double clutch  1 . 
         [0031]    It is also conceivable to only provide the shafts  3 ,  12 ,  13  located downstream with turbines  47 , in order to ensure a lubrication of their roller bearings which is qualitatively equivalent to the lubrication of the roller bearings  45 ,  46 . 
         [0032]    The embodiments have been described above especially with reference to a transmission having double clutch, since such transmissions represent a preferred area of application. The increased space requirement of the double clutch  1  in comparison to a typical single clutch results in strong contouring of the wall  35 , having a projection  57  protruding far into the transmission housing  29  around the input shafts, which makes the oil supply of the roller bearings  58 , which bear the shafts  3 ,  4 ,  12 ,  13  on the side of the wall  35 , difficult via lines guided in the wall  35 . However, it is obvious that the invention is also usable in other constructions of transmissions or in general for the oil supply of any desired lubrication points in diverse types of machines. 
         [0033]    While at least one exemplary embodiment has been presented in the foregoing summary and detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration in any way. Rather, the foregoing summary and detailed description will provide those skilled in the art with a convenient road map for implementing an exemplary embodiment, it being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope as set forth in the appended claims and their legal equivalents.