Abstract:
A lubrication system is provided for a vehicle transmission having shaft bearings, gearwheel hub bearings, gear rings of interlocking gear shift gearwheel pairs, and rotationally-fixed, axially-displaceable mounts of synchronous clutch elements. The lubricant is kept in a loop, which is supported by gravity and lubricant guide components. For a first, a second, and a third lubrication area, a first, a second, and a third lubricant passage, respectively, are provided, having drip openings to the respective lubrication areas situated underneath. A crown wheel protrudes into a lower lubricant collection volume, and a lubricant guide channel extends from an outer circumference of the crown wheel to an upper lubricant collection volume

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to German Patent Application No. 102009052595.5, filed Nov. 10, 2009, which is incorporated herein by reference in its entirety. 
       TECHNICAL FIELD 
       [0002]    The invention relates to a lubrication system for a vehicle transmission having shaft bearings, gearwheel hub bearings, gear rings of interlocking gear shift gearwheel pairs, and rotationally-fixed, axially-displaceable mounts of synchronous clutch elements. The lubricant is kept in a loop which is supported by gravity and lubricant guide components. 
       BACKGROUND 
       [0003]    A lubrication system for a vehicle transmission is known from the publication U.S. Pat. No. 7,513,172 B2 and comprises a transmission housing having shafts situated therein, a rotation part, which is situated in an end section of the housing, ensuring lubricant oil loop. The rotation part is designed so that it lifts lubricant oil to transport the lubricant oil to an area which is spaced apart from the end section inside the housing. An oil passage is provided along the axial direction of the shafts in the transmission housing for this purpose. The oil passage is constructed to receive the lubricant oil which was lifted by the rotation part and to transport the lubricant oil in the longitudinal direction of the oil passage to a second forward end of the transmission housing in the longitudinal direction to an area inside the housing, which is far away from the rotation part. The oil passage is integrally formed with the housing. 
         [0004]      FIG. 7  shows a schematic cross-section through such a transmission  60  according to the prior art, whose transmission housing  47  comprises three parts, a forward first part  63  and a second part  64 , which together already have the complete function of the transmission having shaft bearings  4  to  9 , gearwheel hub bearings  10  to  15 , gear rings  16  to  27 , and gear shift gearwheel pairs  29  to  34 , three synchronous clutch elements  35 ,  36 , and  37  allowing the shifting of the individual gears. 
         [0005]    A third part  65  is flanged onto this complete, fully functional vehicle transmission  60  having a total of six gears, including reverse gear. The third part  65  corresponds in its longitudinal extension to at least one of the two first housing sections  63  or  64 . This third housing part only contains a crown wheel  50 , which is driven via a bevel gear pinion  66 . The bevel gear pinion  66  is situated on an end of a lower transmission hollow shaft  52  and protrudes into the third housing part  65 . The crown wheel  50  essentially determines the large longitudinal extension of the third housing part  65  by its diameter, which corresponds to the clearance of the vehicle transmission  60 . 
         [0006]    The outer circumference  48  of the crown wheel  50  is immersed in a lubricant sump or a lower lubricant collection volume  49  and the crown wheel rotates in the arrow direction A. The lubricant oil is carried out of the lower lubricant collection volume  49  and transported into an upper lubricant passage  44 , so that the lubricant oil is transported in the upper lubricant passage  44  in the arrow direction B up into the forward first housing part  63 . In addition, the passage has drip openings (not shown here), via which the area of the transmission, which lies below the lubricant passage, having its upper transmission hollow shaft  54  and its lower transmission hollow shaft  52 , is supplied with lubricant oil. 
         [0007]    The lubricant is thus guided in a loop  38  in the arrow direction C and supplied in the lower area of the transmission in the arrow directions D and E to the lower lubricant collection volume  49  in the third housing section  65 . In addition, the hollow shafts  52  and  54  have radial supply holes  56  to the shaft bearings  4  to  9  and radial supply holes  55  to the hub bearings  10  to  15  of the gearwheels. 
         [0008]    Such a lubrication system  2  having such a complex crown wheel  50  has the disadvantage that the vehicle transmission  60  must be lengthened by more than half of one transmission length in order to ensure the lubrication system. This means a high manufacturing and cost expenditure, as well as a high space requirement, which is often unavailable in the engine compartment of a vehicle. 
         [0009]    At least one object of the invention is therefore to specify a lubrication system, which is designed significantly more compactly and effectively and does not substantially increase the overall length of the transmission to be lubricated. 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 
       [0010]    According to an embodiment of the invention, a lubrication system is provided for a vehicle transmission having shaft bearings, gearwheel hub bearings, gear rings of interlocking gear shift gearwheel pairs, and rotationally-fixed, axially-displaceable mounts of synchronous clutch elements. The lubricant is kept in a loop which is supported by gravity and lubricant guide components. For a first, a second, and a third lubrication area, a first, a second, and a third lubricant passage, respectively, having drip openings to the respective lubrication areas situated underneath are provided. A crown wheel protrudes into a lower lubricant collection volume, and a lubricant guide channel extends from an outer circumference of the crown wheel to an upper lubricant collection volume. 
         [0011]    Such a lubrication system for a vehicle transmission has the advantage that the required crown wheel can have a significantly reduced diameter in relation to the prior art, since the lubricant is spun via the outer circumference of the crown wheel into a lubricant guide channel. The lubricant guide channel overcomes the further height difference from the outer circumference of the crown wheel up to an upper lubricant passage. Because of the lubricant guide channel, the crown wheel can thus have a significantly smaller diameter. 
         [0012]    In addition, the crown wheel can be coupled to the lower hollow shaft of the transmission, without requiring an additional bevel gear, since it is preferably oriented parallel to the transmission gearwheel pairs, in contrast to the prior art. The crown wheel is also situated on an end section of the transmission housing, but it does not rotate transversely to the transmission shafts, so that the transmission housing lengthening can be kept to a minimum, namely to the thickness of the crown wheel, and does not require a housing lengthening, which practically corresponds in its longitudinal extension to the outer diameter of the crown wheel, as in the prior art. 
         [0013]    In addition, the crown wheel can be made smaller and lighter, since the lubricant guide channel according to an embodiment of the invention receives the lubricant from the outer circumference of the crown wheel and guides the lubricant up into the uppermost area of the transmission housing. Multiple lubricant passages may thus now be supplied from above from one upper lubricant collection volume. The lubricant can be transported and distributed directly via corresponding drip openings in the lubricant passage into the various areas of the transmission, which are situated below the lubricant passage. In addition to the first upper lubricant passage, a laterally offset second lubricant passage is also connected to the upper lubricant collection volume. In addition, it is possible that the lubricant guide channel supplies an upper transmission hollow shaft with lubricant, the upper transmission hollow shaft having radial supply holes to shaft and hub bearings. 
         [0014]    Through the positioning of lubricant holes in the housing walls, in a further embodiment of the invention, the hollow shafts of the transmission may be supplied with lubricants. For this purpose, a first lubricant hole is situated in the transmission housing, which is connected to the upper lubricant collection volume and supplies the third lower lubricant passage with lubricant. A connection is thus provided between the upper lubricant collection volume and the lower lubricant passage via this additional lubricant hole, which is situated in the transmission housing without requiring additional space. This acts in a space-saving and cost-effective manner on the overall concept of the lubrication system for a vehicle transmission according to an embodiment of the invention. 
         [0015]    Furthermore, it is provided that a second lubricant hole is situated in the transmission housing, which is connected to the upper lubricant collection volume and supplies a lower transmission hollow shaft with lubricant, the lower transmission hollow shaft having radial supply holes to shaft and hub bearings. With this further embodiment of the invention, the lower areas of the vehicle transmission are connected to the upper lubricant collection volume and the lubricant loop, so that all areas of the transmission are now supplied directly and reliably with lubricant. 
         [0016]    In order to throttle the lubricant transport through the crown wheel, in a further embodiment of the invention, a throttle plate is additionally situated in the lower lubricant collection volume. Such a throttle plate ensures that only a partial area of the lower lubricant collection volume is made available to the crown wheel for the further transport in the lubricant loop. 
         [0017]    Such a lubrication system is preferably used for a vehicle transmission and has a preferred application as a lubrication system in motor vehicle transmissions. Existing cavities of the conventional transmission are used for the design of the three provided lubricant passages, so that no additional space requirement arises for the three lubricant passages. An additional space requirement only arises due to the thickness of the crown wheel and the lubricant guide channel adjoining the crown wheel. However, this additional transmission volume can also be shrunk significantly in relation to the known prior art because of the novel orientation of the crown wheel, namely transversely to the transmission shafts. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]    The present invention will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements, and. 
           [0019]      FIG. 1  shows a schematic perspective, partially cutaway view of a vehicle transmission having lubrication system according to an embodiment of the invention; 
           [0020]      FIG. 2  shows a schematic perspective view of the spatial configuration of lubricant guiding components of a lubricant loop in a vehicle transmission according to  FIG. 1 ; 
           [0021]      FIG. 3  shows a schematic perspective view of the spatial configuration of a lubricant guide channel and an upper lubricant collection volume having connected first lubricant passage; 
           [0022]      FIG. 4  shows a schematic perspective view of the second lubricant passage; 
           [0023]      FIG. 5  shows a schematic perspective view of the third lubricant passage; 
           [0024]      FIG. 6  shows a schematic perspective view of the throttle plate in the lower lubricant collection volume; and 
           [0025]      FIG. 7  shows a schematic cross-section through a vehicle transmission having a lubrication system according to the prior art. 
       
    
    
     DETAILED DESCRIPTION 
       [0026]    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. 
         [0027]      FIG. 1  shows a schematic perspective, partially cutaway view of a vehicle transmission  3  having lubrication system  1  according to one embodiment of the invention. Of the vehicle transmission  3 , only the outlines of the transmission housing  47  are shown, as well as a plurality of lubricant guide components  40 , which ensure that a lubricant is transported from a lower lubricant collection volume  49  into an upper lubricant collection volume  53  via a lubricant guide channel  51 . The various transmission shafts and transmission gearwheels are supplied with lubricant from the upper lubricant collection volume  53  with the aid of gravity and flow velocity of the lubricant. 
         [0028]    Of the transmission housing  47 , the contour of a transmission housing flange  67  is shown, which can be flanged onto a corresponding clutch. A crown wheel  50  having a relatively small external diameter is immersed in the lower lubricant collection volume  49  and transports or spins, using its outer circumference  48 , the lubricant from the lower lubricant collection volume  49  in the arrow direction A through a lubricant guide channel  51  to the upper lubricant collection volume  53 . An upper first lubricant passage  44 , which can supply an upper area  41  of the transmission  3  situated beneath it with lubricant via corresponding drip openings  39  in the arrow direction B, is connected to the upper lubricant collection volume  53 . 
         [0029]    Laterally offset to the upper first lubricant passage  44 , a second lubricant passage  45  is connected to the upper lubricant collection volume  53  via a lubricant distributor  69 . The second lubricant passage  45  supplies an area  42  of the transmission  3  situated underneath it with lubricant via corresponding drip openings  39  in the specified arrow directions C. In this lubrication system  1  according to the invention, it is noteworthy that sufficient lubricant can be kept in the loop  38  using a relatively small crown wheel  50 , whose diameter is significantly smaller than the diameter in the prior art according to  FIG. 7 , to accordingly supply shaft bearings, gearwheel hub bearings, gear rings, and synchronous clutch elements with sufficient lubricant. 
         [0030]    In order to ensure that sufficient lubricant is available in the lower area  43  of the transmission  3 , lubricant holes  57  for supplying a lower lubricant passage  46  and a further lubricant hole  58  for supplying a lower transmission hollow shaft  52  are situated in the transmission housing wall. The lubricant holes  57  and  58  are indicated by dashed lines and connect the upper lubricant collection volume  53  via the lubricant distributor  69  to the lower third lubricant passage  46  or the lower transmission hollow shaft  52 , respectively. The transmission shafts are implemented as hollow shafts in this embodiment of the invention, as in the prior art corresponding to that shown in  FIG. 7 , which have radial lubricant distribution holes, to supply hub bearings and shaft bearings with lubricant. 
         [0031]    A characterizing feature of this lubrication system  1  according to an embodiment of the invention is a relatively small crown wheel  50 , using which the loop  38  of the lubrication is kept moving. This crown wheel  50  rotates parallel to the transmission gearwheel pairs, in contrast to the prior art, and is situated toward the clutch on the transmission housing flange  67  and not positioned on the diametrically opposing end  68  of the transmission housing  47 , in contrast to the prior art. The diametrically opposing end  68  of the transmission housing  47  has so-called automatic oilers, as are shown in the following figure, which may be situated on ends of transmission shafts and may distribute lubricant in the transmission volume there from. 
         [0032]    In addition, a throttle plate  28  is situated in the lower lubricant collection volume  49 , which throttles the inflow of lubricant to the crown wheel  50  to a reasonable amount, so that sufficient lubricant can always be provided for the lubricant loop  38 , without the lower lubricant collection volume being run dry by the crown wheel. 
         [0033]      FIG. 2  shows a schematic perspective view of the spatial configuration of lubricant guide components  40  of a lubricant loop  38  in a vehicle transmission  3  according to  FIG. 1 . Components having identical functions as in  FIG. 1  are identified by identical reference numerals and are not explained separately. A coordinate system having x, y, and z axes is incorporated in  FIG. 2  as an orientation aid for the spatial configuration, the z axis showing the configuration of the lubricant guide components  40  with respect to the height in the transmission and the x axis being situated in the longitudinal direction of the hollow shafts, while the y axis shows the transverse direction in the transmission  3 . 
         [0034]    In addition, the illustration of the crown wheel, as shown in  FIG. 1 , was dispensed with. For this purpose, the throttle plate  28  is visible at the lowest point of the transmission  3  in the area of the lower lubricant collection volume. The function of the throttle valve was already explained in the introduction with  FIG. 1 , so that a repetition is superfluous here. The lubricant guide channel  51 , in which the lubricant is guided to the upper lubricant collection volume  53  and is distributed from there to the upper lubricant passage  44  and a laterally offset second lubricant passage  45 , is situated above the throttle plate  28  and above the crown wheel (not shown here). 
         [0035]    As already explained in  FIG. 1 , the lower areas of the transmission are supplied by a lower third lubricant passage  46 , each of the lubricant passages  44  to  46  having drip openings  39 , via which the lubricant areas situated below the lubricant passages are supplied. In addition to the lubricant passages, so-called automatic oilers  59 ,  61 , and  62  are situated on the diametrically opposite end to the transmission input flange and are connected to end areas of the transmission shafts, which ensure that the remaining lubricant is distributed uniformly in this area of the transmission. 
         [0036]      FIG. 3  shows a schematic perspective view of the spatial configuration of a lubricant guide channel  51  and an upper lubricant collection volume  53  having connected first lubricant passage  44 . The upper lubricant collection volume  53  not only supplies the upper lubricant passage  44  but rather also a lubricant distributor  69 , onto which a second laterally offset lubricant passage can be flanged. This lubricant distributor  69  has, in addition to an opening  70  for this second laterally offset lubricant passage, further openings  71  and  72 , which are connected to lubricant holes in the housing wall, to supply lower areas of the transmission  3  with lubricant. 
         [0037]      FIG. 4  shows a schematic perspective view of the second lubricant passage  45  in detail, which can be flanged onto the opening  70  of the lubricant distributor  69  shown in  FIG. 3  or inserted into this opening  70 . This lubricant passage is also provided with corresponding drip openings  39 , through which the lubricant can drip into a lubricant area, which is situated below the lubricant passage  45 . 
         [0038]      FIG. 5  shows a schematic perspective view of the third lubricant passage  46 , which is connected via a lubricant hole in the housing wall to the lubricant distributor  69 , which is shown in  FIG. 3 . 
         [0039]      FIG. 6  shows a schematic perspective view of the throttle plate  28  as a lubricant guide component  40 , which is immersed in the lower lubricant collection volume and throttles the supply of lubricant to the crown wheel (not shown). The throttle plate  28  merges into an angled plate, which is used as a fastening flange  73  for the throttle plate  28  within the transmission housing. 
         [0040]      FIG. 7  shows a schematic cross-section through a vehicle transmission  60  having a lubrication system  2  according to the prior art, as was already explained at the beginning, so that a further explanation is superfluous. 
         [0041]    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.