Abstract:
One implementation of a vehicle power transfer unit (PTU) housing, such as that for an automobile, has an oil feed passage extending through one of its walls and at its interior. The oil feed passage delivers oil to gears, bearings, and/or other components equipped inside of the PTU housing and suspended above an oil bath in the PTU housing. Oil of the oil bath is thrown about by rotating gears and makes its way through the oil feed passage and to the gears, bearings, and/or other components. With the oil feed passage, the PTU housing does not rely solely on oil sloshing and splashing and being slung around inside of the PTU housing as the technique for getting oil to the gears, bearings, and/or other components.

Description:
REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application Ser. No. 61/925,701 filed on Jan. 10, 2014, the entire contents of which are incorporated herein by reference. 
     
    
     TECHNICAL FIELD 
       [0002]    The present disclosure relates generally to vehicle power transfer units (PTUs), and more particularly to techniques for supplying oil in interiors of vehicle PTUs. 
       BACKGROUND 
       [0003]    In general, vehicle drivelines transmit torque from a vehicle&#39;s engine to its wheels, Automotive drivelines sometimes include power transfer units (PTUs, also known as power take-off units) for selectively distributing torque among shafts in the drivelines. The PTUs are often equipped in four-wheel and all-wheel drive driveline configurations. A power transfer unit typically consists of a housing that encloses and supports gear assemblies, shafts, and bearings, among other possible components. Oil is ordinarily kept in the housing to lubricate the gear assemblies as they rotate and mesh during operation of the driveline, and to lubricate the bearings and other components. The housing is typically filled with oil only partway and not fully, as oil usually makes its way to all of the components when it is sloshed and splashed and slung around in the housing during operation. 
       SUMMARY 
       [0004]    In one implementation, a vehicle power transfer unit (PTU) housing includes one or more walls, an oil feed passage, and an oil feed lead-in formation. An interior is defined in part or more by the wall(s). The oil feed passage extends through the wall(s). The oil feed passage has an inlet open to the interior at a first location, and has an outlet open to the interior at a second location. The second location is situated above an oil resting plane of an oil bath that is held in the PTU housing. When a gear assembly in the interior is operated and rotates, oil from the oil bath is urged through the oil feed passage from its inlet and to its outlet and to the second location. The oil feed lead-in formation is set in the wall(s) and is located near the inlet. The oil feed lead-in formation is shaped and orientated relative to the oil resting plane in order to guide oil into the oil feed passage. 
         [0005]    In another implementation, a vehicle power transfer unit (PTU) housing includes a main wall, an interior all, an interior, an oil feed passage, and an oil feed lead-in formation. The interior wall extends from the main wall. The interior has a first section in which an oil bath is held in the PTU housing, and has a second section that is situated above an oil resting plane of the oil bath. The first section is defined in part or more by an inner surface of the main wall, and the second section is defined in part or more by an inner surface of the interior wall. The oil feed passage extends through the interior wall. The oil feed passage has an inlet that is open to the first section and has an outlet that is open to the second section. The oil feed lead-in formation is set partly or more in the interior wall and near the inlet of the oil feed passage. 
         [0006]    In yet another implementation, a vehicle power transfer unit (PTU) assembly includes housing, a gear assembly, and one or more bearings. The housing includes a main wall, an interior wall, a first interior section, a second interior section, an oil feed passage, and an oil feed lead-information. The interior wall extends from the main wall. The first interior section is defined in part or more by an inner surface of the main wall and holds an oil bath. The second interior section is defined in part or more by an inner surface of the interior wall and is situated outside of the oil bath. The oil feed passage can extend through the main wall, can extend through the interior wall, or can extend through both the main wall and the interior wall. The oil feed passage has an inlet that is open to the first interior section, and has an outlet that is open to the second interior section. The oil feed passage fluidly communicates the first interior section with the second interior section. The oil feed lead-in formation is set in the main wall, is set in the interior wall, or is set in both the main wall and the interior wall. The oil feed lead-in formation is located near the inlet of the oil feed passage. The oil feed lead-in formation has one or more curved surfaces and one or more planar surfaces spanning from the curved surface(s). The gear assembly is located at the first interior section. The bearing(s) is located at the second interior section. Amid operation of the gear assembly at the first interior section, oil of the oil bath impinges the oil feed lead-in formation and is urged through the oil feed passage from the inlet and to the outlet and to the bearing(s). 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    The following detailed description of preferred embodiments and best mode will be set forth with reference to the accompanying drawings, in which: 
           [0008]      FIG. 1  is a perspective view of one part of an embodiment of a power transfer unit (PTU) housing; 
           [0009]      FIG. 2  is a perspective view of the PTU housing of  FIG. 1 , the PTU housing having internal components removed; 
           [0010]      FIG. 3  is a partially sectioned view of the PTU housing of  FIG. 1 , illustrating an embodiment of an oil feed passage; 
           [0011]      FIG. 4  is an enlarged view of an embodiment of an oil feed lead-in formation; 
           [0012]      FIG. 5  is another enlarged view of the oil feed lead-in formation of  FIG. 4 ; and 
           [0013]      FIG. 6  is an enlarged view of the PTU housing of  FIG. 1 , illustrating some internal components. 
       
    
    
     DETAILED DESCRIPTION 
       [0014]    Referring in more detail to the drawings, a power transfer (PTU)  10  of an automotive vehicle is designed to ensure that its gear assemblies, bearings, and other components are properly supplied with oil during operation. The PTU&#39;s oil is urged through an oil feed passage  12  and to a location suspended above the oil, and does not solely rely on oil sloshing and splashing and being slung around as the way to get oil to that location. With the oil feed passage  12 , oil be effectively provided to components when the automotive vehicle is traveling at a lower speed than previously possible. 
         [0015]    The PTU  10  can have different constructions and components depending on, among other factors, the configuration of the driveline in which the PTU is installed. In the example of the figures, the PTU  10  includes a housing  14 , a first gear assembly  15 , and a second gear assembly  16 . Skilled artisans will appreciate that PTUs also conventionally include other components such as shafts scaled into and out of the PTUs, and include additional gear assemblies than those described here. 
         [0016]    The housing  14  encloses and supports components of the PTU  10  such as the first and second gear assemblies  15 ,  16  and shafts. The exact construction of the housing  14  may depend on the configuration of the driveline and on the design of the gear assemblies and shafts. In the embodiment of the figures, and particularly referring to  FIGS. 1 and 2 , the housing  14  includes a set of halves that are bolted and sealed together—just one of the halves is shown. The housing  14  is conventionally composed of a metal material and can be manufactured via casting or another metalworking process. When installed in the driveline, the housing  14  is oriented similarly as depicted in  FIGS. 1 and 2  with its bottom  18  closest to the ground underneath the associate vehicle. A main wall  20  frames the housing  14  and has openings in it for accommodating components of the PTU  10  like input and output shafts. The main wall  20  has an inner surface  22  that partly defines an interior  24 . Since only one-half of the housing  14  is shown, the figures do not necessarily illustrate all of the interior  24 . The interior  24  is the space inside the housing  14  where the gear assemblies are placed and where oil is held. The interior  24  has a first section  26  that provides room for the first gear assembly  15  and that serves as a reservoir for holding an oil bath that lubricates the gear assemblies, bearings, and other components in the PTU  10 . Oil of the oil bath is filled in the first section  26  to an oil line A shown in  FIG. 4 . Here, the oil bath does not completely fill the interior  24 . When inactive and not sloshed about, an upper surface of the oil bath constitutes an oil resting plane generally aligned with the oil line A and spanning horizontally (with respect to  FIG. 1 ) across the interior  24 . 
         [0017]    Referring now to  FIGS. 2 and 4 , the housing  14  also includes an interior wall  28 . The interior wall  28  unitarily extends from the main wall  20  and supports a shaft that carries the second gear assembly  16  when the PTU  10  is assembled together. The interior wall  28  can have a generally circular and cylindrical conformation, as shown in the figures. As depicted in  FIG. 1 , the second gear assembly  16  generally sits above the first gear assembly  15  as their teeth mesh with one another in operation. At least a portion of the interior wall  28  is situated above the oil line A and above the oil resting plane. The interior wall  28  has an inner surface  30  that defines a second section  32  of the interior  24 . The second section  32  is the space inside the interior wall  28  where, in this embodiment, the shaft of the second gear assembly  16  is received. The shaft passes through the second section  32  via an open end  38 . The second section  32  constitutes a cavity defined by the interior wall  28 . The interior wall  28  hence serves as a dividing wall extending within the interior  24  and partitioning the interior  24  into the first and second sections  26 ,  32  and into a cavity above the oil bath and a cavity that holds the oil bath. 
         [0018]    Since the second section  32  is situated above the oil line A and above the oil resting plane, the second gear assembly  16  may not be fully submerged in the oil bath. The second section  32  may thus also not be submerged in the oil bath. In the past, despite their location outside of the oil bath, oil would make its way to a gear assembly and components above the oil bath as the oil was sloshed and splashed and slung around by a gear assembly immersed in the oil bath during operation. But in some cases—including in the embodiment shown in the figures—it has been found that oil does not always find its way to all parts of the second gear assembly  16  and its shaft, especially to those parts sitting within the second section  32  like bearings  40  ( FIG. 6 ). And bearings and components not adequately lubricated have a shorter useful life. Without intending to be bound to specific theories of causation, it is currently believed that oil is precluded from parts of the second gear assembly  16  and its shall and bearings  40  due to the housing&#39;s architecture, due to the second section&#39;s location relative to the oil bath, and due to the interior wall  28  blocking oil from below. 
         [0019]    To resolve these potential shortcomings and ensure that oil is properly supplied to desired parts of the second gear assembly  16  such as at the bearings  40 , the housing  14  is furnished with the oil feed passage  12 . In this particular embodiment, the oil feed passage  12  delivers oil from the first section  26  of the interior  24  and to the second section  32  as oil is thrown around by the first gear assembly  15  during operation of the PTU  10 . The turbulent oil is urged—against gravity and without the use of an oil pump—through the oil feed passage  12  and hence to the second gear assembly  16  and to its shaft and to the bearings  40 . 
         [0020]    Referring to  FIGS. 2-4 , in this embodiment the oil feed passage  12  is an elongated cylindrical channel spanning between the first section  26  and the second section  32 , and fluidly communicates with both of the sections. Here, the oil feed passage  12  has a geometrically linear extent and presents a direct path between the first and second sections  26 ,  32 ; in other words, the oil feed passage can present a straight line between the first and second sections  26 , 32 . Its linear extent can be oriented at an acute included angle β relative to the oil resting plane. The orientation of the oil feed passage  12  relative to the oil resting plane in implementations as presented in the embodiment of the figures—its acute angle—has been found to readily deliver oil through the oil feed passage and to the second section  32 . In other embodiments the oil feed passage  12  could take one or more turns throughout its length and could be at another angle, including a compound angle, relative to the oil resting plane. The oil feed passage  12  can be drilled into the housing  14 , or could be formed via another metalworking process. In one specific example, the oil feed passage  12  is a cylindrical channel with a diameter of approximately 5.5 millimeters (mm); of course, in other examples other values are possible for the diameter, and other shapes and orientations are possible for the oil feed passage. 
         [0021]    The oil feed passage  12  can extend through the main wall  20  of the housing  14 , through the interior wall  28 , or through both walls with one section of the passage in the main wall and another section in the interior wall. Still, the oil feed passage  12  could extend through another wall of another embodiment of a PTU housing. Exactly where the oil feed passage  12  extends may depend on the construction of the housing  14 . In the embodiment of the figures, and referring particularly to  FIG. 4 , from the first section  26  to the second section  32  the oil feed passage  12  begins its extension at a lower portion of the interior wall  28  and terminates its extension at a higher portion of the interior wall. 
         [0022]    The oil feed passage  12  has an inlet  42  at a first location open to the first section  26 , and has an outlet  44  at a second location open to the second section  32 . The inlet  42  is shown as being situated above the oil resting plane, but could be situated below the plane and within the oil bath. The outlet  44  is perhaps best shown in  FIGS. 4 and 6  where it exits the interior wall  28  at a site in the second section  32  in which the bearings  40  are seated when the second gear assembly  16  and its shaft are set into place. In this way, oil leaving the outlet  44  is readily received by the bearings  40 . In other embodiments, the outlet  44  could exit the interior wall  28  at other sites in the second section  32  depending on the desired location of oil relative to the second gear assembly  16  and to its shaft and components. 
         [0023]    Referring now to  FIGS. 4 and 5 , in this embodiment the housing  14  has an oil feed lead-in formation  46 . The oil feed lead-in formation  46  need not be provided in all embodiments of the housing  14 . When provided, the oil feed lead-in formation  46  helps guide turbulent oil impinging and hitting it to the inlet  42  and into the oil feed passage  12 . The oil feed lead-in formation  46  is a wait depression that is located near the inlet  42 , and is shaped so that oil is directed into the oil feed passage  12  via the inlet instead of simply passing over the inlet and avoiding entry into the oil feed passage. In this way, more oil can be delivered through the oil feed passage  12  than may otherwise be the case. The oil feed lead-in formation  46  can have different designs and constructions depending upon, among other possible factors, its location in a housing wall and its location with respect to the oil bath and with respect to turbulent oil. In the embodiment of  FIGS. 4 and 5 , the oil feed lead-in formation  46  is set in an underside of the interior wall  28  and spans just about to the main wall  20 . In other embodiments, the oil feed lead-in formation  46  could be set only in the interior wall  28  or only in the main wall  20 —its location may be dictated by the location of the inlet  42  and the motion and movement of the turbulent and thrown oil. In the figures, the oil feed lead-in  - formation  46  is situated above the oil line A and above the oil resting plane. The inlet  42  is located within the confines of the oil feed lead-in formation  46 . 
         [0024]    The oil feed lead-in formation  46  can be made up of various surfaces that together steer thrown oil toward the inlet  42 , or the oil feed lead-in formation can be made of a single surface shaped to steer thrown oil toward the inlet. In the embodiment presented in the figures, and particularly referring to  FIG. 5 , the oil feed lead-in formation  46  has a first curved surface  48 , a second curved surface  50 , and a flat surface  52 . The surfaces  48 ,  50 ,  52  span from one another and intersect one another. The first curved surface  48  immediately surrounds a portion of the periphery of the inlet  42 . The first curved surface  48  has a concave shape and is orientated to generally confront the oil resting plane of the oil bath. Stilt, in other embodiments, the first curved surface  48  could be made up of numerous smaller planar surfaces angled relative to one another that together generally resemble and serve as a curved surface. In one specific example, its concavity has a radius of approximately 8.0 mm; of course, in other examples other values for the radius are possible. The first curved surface  48  spans longitudinally between a first end  54  and a second end  56 —its longitudinal extent overlaps the inlet  42 . In one specific example, between the first and second ends  54 ,  56 , the first curved surface  48  has a length of approximately 40.0 mm; of course, in other examples other values for the length are possible. And the first curved surface  48  spans transversely between a top edge  58  and a bottom edge  60 —again its transverse extent overlaps the inlet  42 . 
         [0025]    Still referring to  FIG. 5 , in this embodiment the second curved surface  50  also has a concave shape, but is orientated differently than the first curved surface  48 . Its longitudinal extent is arranged at an acute angle relative to the longitudinal extent of the first curved surface  48 . In other embodiments, the second curved surface  50  could be made up of numerous smaller planar surfaces angled relative to one another that together generally resemble and serve as a curved surface. The second curved surface  50  spans longitudinally between a first end  62  and a second end  64 . The second end  64  intersects with a portion of the periphery of the inlet  42 . The second end  64  is wider than the first end  62 , as the second curved surface  50  narrows transversely from the second end  64  and toward the first end. In one specific example, between the first and second ends  62 ,  64 , the second curved surface  50  has a length of approximately 38.7 mm; of course, in other examples other values for the length are possible. Further, the second curved surface  50  spans transversely between a first edge  66  and a second edge  68 . 
         [0026]    Lastly, the flat surface  52  has a generally planar shape and is generally level across its extent. In the embodiment of  FIG. 5 , the flat surface  52  spans from both of the first and second curved surfaces  48 ,  50  and shares an end and an edge with the curved surfaces. The flat surface  52  spans longitudinally between a first end  70  and a second end  72 , and spans transversely between a top edge  74  and a bottom edge  76 . Unlike the first and second curved surfaces  48 ,  50 , the area defined by the flat surface  52  does not overlap the inlet  42 . In one specific example, between the first and second ends  70 ,  72  and at the bottom edge  76 , the flat surface  52  has a length of approximately 69.0 mm; of course, in other examples other values for the length are possible. Furthermore, in this embodiment, an inclined or tapered surface  78  spans transversely from the bottom edge  76  of the flat surface  52  and merges into the inner surface  22  of the main wall  20 . 
         [0027]    Depending on its design and construction, the oil feed lead-in formation  46  can be produced as part of the housing&#39;s casting process. With casting, the oil feed lead-in formation  46  can be fashioned it the main wall  20  or in the interior wall  28  to facilitate the manufacturing process by, for instance, creating a tapered transition between the oil feed lead-in formation and adjacent wall. Still, in another manufacturing process, the oil feed lead-in formation  46  could be machined into the main wall  20 , into the interior wall  28 , or into both walls. 
         [0028]    Referring back to  FIG. 1 , the first gear assembly  15  is interconnected to a shaft, and is set in the interior  24  at the first section  26  where it is partly or more submerged in the oil bath. In one example the first gear assembly  15  is a ring gear assembly, but could be a spur gear, beveled gear, hypoid gear, helical gear, or another gear type. 
         [0029]    The second gear assembly  16  is interconnected to a shaft, and is set in place at one end at the second section  32 . As described earlier, the second gear assembly  16  could sit mostly above the oil resting plane and above the oil bath. In one example the second gear assembly  16  is a helical gear assembly, but could be a spur gear, beveled gear, hypoid gear, ring gear, or another gear type. Referring now to  FIG. 6 , the bearings  40  could be ball bearings, needle bearings, roller bearings, thrust bearings, angular ball bearings, tapered roller bearings, thrust needle roller bearings, or another bearing type. The bearings  40  can be an integral part of the second gear assembly  16 , or could be a discrete part. A seat defined in the interior wall  28  at the second section  32  receives the bearings  40  in assembly and in installation. The seat can be a circular groove defined in the inner surface  30 . 
         [0030]    Referring now to  FIG. 6 , during operation as the first and second gear assemblies  15 ,  16  rotate, the first gear assembly can cause sloshing and splashing of the oil in the oil bath, and can sling the oil around the interior  24 . The resulting turbulent and thrown oil can be raised above the oil line A, and can impinge the oil feed lead-in formation  46  in which case it would be guided toward the inlet  42 . The oil is then urged through the oil feed passage  12  and to the second gear assembly  16  and to the bearings  40 . The route taken by the oil described here is represented by the arrows B in  FIG. 6 ; still, other routes are possible. Further, arrow C depicts the rotation direction of the first gear assembly  15 . With this rotation direction, the turbulent and thrown oil may be more readily directed toward the oil feed passage  12 , and the oil feed lead-in formation  46  can be located in a position to guide the turbulent and thrown oil according to this rotation direction, as shown in  FIG. 6 . 
         [0031]    While the oil feed passage has been depicted in one example PTU housing, it is intended that the oil feed passage could be employed in other examples. Indeed, the oil feed passage could be useful in PTU housings where oil is precluded from effectively making its way to gear assemblies and bearings suspended above the oil, or here oil is not otherwise accessible to the gear assemblies and bearings. 
         [0032]    While the forms of the invention herein disclosed constitute presently preferred embodiments, many others are possible. It is not intended herein to mention all the possible equivalent forms or ramifications of the invention. It is understood that the terms used herein are merely descriptive, rather than limiting, and that various changes may be made without departing from the spirit or scope of the invention.