Abstract:
A compressor oil seal comprising a thrust bearing ( 59 ) adapted for insertion into a turbocharger housing cavity ( 33 ), concentric with the turbocharger&#39;s compressor wheel shaft ( 11 ). An insert ( 360 ) is adapted for insertion into the cavity ( 33 ) adjacent the thrust bearing ( 59 ), wherein the thrust bearing ( 59 ) and insert ( 360 ) are configured to provide an oil drain cavity ( 35 ) therebetween. The oil seal also includes an oil flinger ( 340 ) that includes a flinger flange ( 382 ) and a sleeve portion ( 383 ) extending therefrom. The flinger flange ( 382 ) extends between the thrust bearing ( 59 ) and the insert ( 360 ). A plurality of spiral vane segments ( 74 ) are circumferentially spaced about the flinger flange ( 382 ). Each spiral vane segment ( 74 ) extends arcuately from a first end ( 372 ) to a second end ( 373 ). The spiral vane segments ( 74 ) are disposed between the flinger flange ( 382 ) and the insert ( 360 ). The spiral vane segments ( 74 ) may extend into a recess ( 363 ) formed into the insert ( 360 ), and the recess ( 363 ) may include at least one discharge port ( 370 ).

Description:
BACKGROUND 
       [0001]    Turbochargers are a type of forced induction system. Turbochargers deliver air, at greater density than would be possible in a normally aspirated configuration. The greater air density allows more fuel to be combusted, thus boosting the engine&#39;s horsepower without significantly increasing engine weight. A smaller turbocharged engine, replacing a normally aspirated engine of a larger physical size, will reduce the mass of the engine and can reduce the aerodynamic frontal area of the vehicle. 
         [0002]    With reference to  FIG. 1 , turbochargers use the exhaust flow from the engine exhaust manifold to drive a turbine wheel  10 . Once the exhaust gas has passed through the turbine wheel and the turbine wheel has extracted energy from the exhaust gas, the spent exhaust gas exits a turbine housing (not shown). The energy extracted by the turbine wheel is translated to a rotating motion which then drives a compressor wheel  32 . The compressor wheel draws air into the turbocharger, compresses this air and delivers it to the intake side of the engine. The rotating assembly consists of the following major components: turbine wheel  10 , shaft  11  upon which the turbine wheel is mounted, compressor wheel  32 , flinger  40 , and thrust components. The shaft  11  rotates on a hydrodynamic bearing system  18  which is fed oil, typically supplied by the engine. The oil is delivered via an oil feed port  21  to feed both journal and thrust bearings. The thrust bearing  59  controls the axial position of the rotating assembly relative to the aerodynamic features in the turbine housing and compressor housing. In a manner somewhat similar to that of the journal bearings, the thrust loads are carried typically by ramped hydrodynamic bearings working in conjunction with complementary axially-facing rotating surfaces of a flinger  40 . The turbocharger includes a housing  20  with a cavity  33 . The thrust bearing  59  and insert  60  are disposed in the cavity and provide an oil drain cavity  35 . Once used, the oil drains to the bearing housing and exits through an oil drain  22  fluidly connected to the engine crankcase. 
         [0003]    Gas and oil passage from within a turbocharger bearing housing to the compressor or turbine stages of a turbocharger is not permitted by engine manufacturers as it contributes to emissions generation and can poison catalysts. Turbocharger manufacturers have been using seal rings, typically piston rings, to seal gases and oil from communicating between the bearing housing cavity and turbine, and/or compressor stages, since turbochargers were first in mass production in Diesel engines in the 1950s. 
         [0004]    Seal means such as seal rings, sometimes also called piston rings, are commonly used within a turbocharger to create a seal between the static bearing housing and the dynamic rotating assembly (i.e., turbine wheel, compressor wheel, flinger, and shaft) to control the passage of oil and gas from the bearing housing to both compressor and turbine stages and vice versa. 
         [0005]    With reference to  FIG. 2 , the typical seal ring ( 46 ,  47 ) has a rectangular cross section which is partially disposed in a groove in the flinger  40 , providing partial sealing between the shaft and its bore. It is well known in the art that these seals suffer from at least some leakage depending on the conditions across the seal. The flinger  40  helps direct oil away from these seals. While existing flinger designs are effective in keeping oil away from the seal rings, there is still room for improvement as emission requirements become ever-stricter. 
       SUMMARY 
       [0006]    Provided herein is a compressor oil seal. In one exemplary embodiment, the oil seal comprises a thrust bearing adapted for insertion into a turbocharger housing cavity, concentric with the turbocharger&#39;s compressor wheel shaft. An insert is adapted for insertion into the cavity adjacent the thrust bearing, wherein the thrust bearing and insert are configured to provide an oil drain cavity therebetween. The oil seal also includes an oil flinger that includes a flinger flange and a sleeve portion extending therefrom. The flinger flange extends between the thrust bearing and the insert and the sleeve portion extends axially into an insert bore formed through a central portion of the insert. 
         [0007]    In one aspect of the technology described herein, a plurality of spiral vane segments are circumferentially spaced about the flinger flange. Each spiral vane extends arcuately from a first end to a second end. The spiral vane segments are disposed between the flinger flange and the insert. The spiral vane segments may extend into a recess formed into the insert. The recess may include at least one discharge port. 
         [0008]    Also contemplated herein is a turbocharger incorporating the disclosed compressor oil seal. In an embodiment, the turbocharger comprises a compressor wheel and a turbine wheel mounted on opposite ends of a shaft. The turbocharger includes a housing supporting the shaft and including a cavity formed adjacent the compressor wheel. A thrust bearing and an adjacent insert are disposed in the cavity. The turbocharger includes an oil flinger including a flinger flange and a sleeve portion extending therefrom. The flinger flange extends between the thrust bearing and the insert and the sleeve portion extends axially into an insert bore formed through a central portion of the insert. A plurality of spiral vane segments are circumferentially spaced about the flinger flange and are disposed on an axially facing surface of the flinger flange. 
         [0009]    In one aspect of the disclosed technology, the spiral vane segments are located between the flinger flange and the thrust bearing. In another aspect of the technology, the spiral vane segments are located between the flinger flange and the insert. Each spiral vane extends arcuately from a first end to a second end, wherein the first end is located at a radius on the flinger flange that is smaller than a radius at which the second end is located. The flinger may also include a seal ring disposed in a groove formed around the sleeve portion. 
         [0010]    These and other aspects of the flinger oil seal will be apparent after consideration of the Detailed Description and Figures herein. It is to be understood, however, that the scope of the invention shall be determined by the claims as issued and not by whether given subject matter addresses any or all issues noted in the background or includes any features or aspects recited in this summary. 
     
    
     
       DRAWINGS 
         [0011]    Non-limiting and non-exhaustive embodiments of the flinger oil seal, including the preferred embodiment, are described with reference to the following figures, wherein like reference numerals refer to like parts throughout the various views unless otherwise specified. 
           [0012]      FIG. 1  is a side view in cross-section of a typical turbocharger; 
           [0013]      FIG. 2  is an enlarged partial cross-section of a typical compressor end sealing package; 
           [0014]      FIG. 3  is a partial cross-section of an flinger oil seal according to a first exemplary embodiment; 
           [0015]      FIG. 4  is an end view in cross-section of the seal shown in  FIG. 3  taken about line  4 - 4 ; 
           [0016]      FIG. 5  is an enlarged partial cross-section of the flinger oil seal shown in  FIGS. 3 and 4 ; 
           [0017]      FIG. 6A  is an enlarged partial cross-section view of a flinger ring shown in  FIGS. 3-5 ; 
           [0018]      FIG. 6B  is an enlarged partial cross-section view of the flinger rings shown in  FIG. 6A  illustrating the oscillation of the flinger; 
           [0019]      FIG. 7A  is a partial cross-section of a flinger oil seal according to a second exemplary embodiment; 
           [0020]      FIG. 7B  is an end view in cross-section of the seal shown in  FIG. 7A  taken about line  7 B- 7 B; 
           [0021]      FIG. 8  is an end view in cross-section of a flinger oil seal according to a third exemplary embodiment; 
           [0022]      FIG. 9A  is an enlarged partial cross-section of the flinger oil seal shown in  FIG. 8 ; 
           [0023]      FIG. 9B  is an end view in cross-section of the seal shown in  FIG. 9A  taken about line  9 B- 9 B; 
           [0024]      FIG. 10A  is a cross-section view of a flinger oil seal according to a fourth exemplary embodiment; 
           [0025]      FIG. 10B  is an end view in cross-section of the seal shown in  FIG. 10A  taken about line  10 B- 10 B; 
           [0026]      FIG. 11A  is a cross-section view of a spiral vane turbine shield according to a fifth exemplary embodiment; and 
           [0027]      FIG. 11B  is an end view of the spiral vane turbine shield shown in  FIG. 11A . 
       
    
    
     DETAILED DESCRIPTION 
       [0028]    Embodiments are described more fully below with reference to the accompanying figures, which form a part hereof and show, by way of illustration, specific exemplary embodiments. These embodiments are disclosed in sufficient detail to enable those skilled in the art to practice the invention. However, embodiments may be implemented in many different forms and should not be construed as being limited to the embodiments set forth herein. The following detailed description is, therefore, not to be taken in a limiting sense. It should be understood that not all of the components of a turbocharger are shown in the figures and that the present disclosure contemplates the use of various turbocharger components as are known in the art. Turbocharger construction is well understood in the art and a full description of every component of a turbocharger is not necessary to understand the technology of the present application, which is fully described and disclosed herein. 
         [0029]    The shaft-and-wheel assembly does not rotate perfectly about the centerline of the bearing housing. Each end of the shaft-and-wheel (turbine-end and compressor-end) describes independent orbits, the loci of which are not necessarily on the centerline of the bearing housing. In addition to these orbits, it has been determined that the rotating assembly tilts about a point located at approximately the center of the turbine-end journal bearing. In other words, at the intersection of the turbocharger centerline  1  and the axial centerline  24  of the turbine-end journal bearing as depicted in  FIG. 1 . The tilt of the compressor-end rotating components about the tilt center causes the need for some (additional) radial and axial clearance between complementary components to limit the chance of contact. 
         [0030]    Disclosed herein is an oil seal that makes use of the orbital motion of the rotating assembly. In one embodiment, for example, this is accomplished with a series of rings or vanes that are disposed on an axially facing surface of the flinger such that each vane is concentric with the flinger&#39;s geometric axis of rotation  1 . The vanes rotate in a complementary coaxial groove or recess fabricated into an axially facing face of the insert. A series of discharge ports are formed in the rotating flinger that allow the egress of oil captured by the orbital rotation of the dynamic ring in the static groove thereby inhibiting said oil from migrating towards the seal rings. 
         [0031]      FIGS. 3-6B  illustrate a flinger oil seal according to a first exemplary embodiment. The oil seal includes a flinger  140  and a corresponding insert  160 . Flinger  140  includes a flinger flange  182  and a sleeve portion  183  extending therefrom. The flinger flange  182  extends between the thrust bearing  59  and the insert  160 . The sleeve portion  183  extends axially into an insert bore  185  formed through a central portion of the insert  160 . Flinger  140  includes a plurality of rings  78  disposed on flinger flange  182  that are concentric with shaft  11 . With reference to  FIG. 5 , each ring  78  fits into a complementary groove  64  formed in insert  160 . Each groove  64  includes radially facing surfaces  62  and an axially facing surface  66  (See  FIGS. 6A and 6B ). Each ring  78  includes an axially facing end face  75  and two radially facing side walls  76 . Flinger  140  also includes oil discharge ports  70  extending from the inside corner of each ring  78 . Discharge ports  70  fluidly couple the volume between the insert  160  and the flinger  140  with the open volume between the turbine side face of the flinger and the thrust bearing  59 . Because the flinger oscillates while rotating, a pumping action is generated between the complementary surfaces of the rings  78  and the grooves  64  in which they reside, thereby forcing any oil which enters the volume between the flinger and the insert to be forced out through the plurality of oil discharge ports  70  and away from the seal rings  46 ,  47 . Each oil discharge port  70  is angled towards the outer diameter of the flinger  140  causing centrifugal force to act on the oil  80  in the discharge port  70  which assists in purging the oil  80  out of the port. 
         [0032]    Comparing  FIGS. 6A and 6B , the oscillations about the turbine-end journal bearing causes the distance between the radially-facing surfaces  76  and the complementary radially-facing surfaces  62 , to cyclically grow and shrink. To provide more clearance due to this mechanical action, and to assist in manufacturability, a taper can be formed onto the ring&#39;s radially facing surfaces  76 . It is assumed that in the manufacturing process the rings  78  can be partially or fully “coined” into the flinger radially-facing surface. A similar taper may also be provided on the radially-facing sidewalls  62  of the grooves  64  in the insert. 
         [0033]    While the rings  78  in the first embodiment are shown to circumscribe a complete circle (360°), the rings may be segmented thus forming individual vanes which can allow the oil, locally pressurized by the oscillating rotation of the vanes in the groove, to escape away from the seal rings more rapidly, thus improving the efficiency of the seal mechanism. Also, although the first embodiment is shown in the figures to have a plurality of rings and complementary insert grooves, a single ring and groove arrangement is contemplated. Furthermore, the rings and grooves may be switched between the insert and flinger. Specifically, the grooves may be formed into the flinger, and the rings may be disposed on the insert. In such a case, the oil discharge port would preferably still be in the dynamic component (i.e. flinger) so that the oil is centrifugally ejected from the system. Also, while the vanes are shown in the figures as being disposed between the insert and the flinger flange, the vanes may be disposed between the flinger flange and the thrust bearing. 
         [0034]      FIGS. 7A and 7B  illustrate a flinger oil seal according to a second exemplary embodiment. In this embodiment, a spiral vane  71  is disposed on the flinger  240  and centered on the geometric axis of rotation  1  of the flinger  240 . Flinger  240  includes a flinger flange  282  and a sleeve portion  283  extending therefrom. The flinger flange  282  extends between the thrust bearing  59  and the insert  260 . The sleeve portion  283  extends axially into an insert bore  285  formed through a central portion of the insert  260 . Spiral vane  71  fits into a single cylindrical concentric recess  77  formed in the insert  260 . Rotation of the flinger  240  (clockwise in  FIG. 7B ) causes the leading edge  72  of the spiral vane  71  to divert the flow of oil, gas, or solids which have worked their way toward the seal rings ( 46 ,  47 ), onto the radially facing surface of rotating spiral vane  71 , which then guides the flow of said unwanted oil, gas, or solids toward the radially facing inner lip  262  of the insert and out of the enclosure via the oil discharge ports  270  in the insert. 
         [0035]    A flinger oil seal according to a third exemplary embodiment, is shown in  FIGS. 8-9B , and includes a plurality of spiral vane segments  74  circumferentially spaced about flinger  340 . Flinger  340  includes a flinger flange  382  and a sleeve portion  383  extending therefrom. The flinger flange  382  extends between the thrust bearing  59  and the insert  360 . The sleeve portion  383  extends axially into an insert bore  385  formed through a central portion of the insert  360 . The sleeve portion  383  includes a pair of grooves  345  and  348  in which are disposed mating seal rings  46  and  47 . 
         [0036]    Rotation of the flinger  340  (clockwise in  FIGS. 8 and 9B ) causes the leading edges  372  of the spiral vane segments  74  to divert the flow of oil, gas, or solids which have worked their way toward the seal rings ( 46 ,  47 ), onto the rotating spiral vane segments, which then guide the flow of said unwanted oil, gas, or solids toward the radially facing inner lip  362  of recess  363  formed in insert  360  and out of the recess via the oil discharge ports  370 . An advantage of having four individual vanes, rather than the single long vane of the second embodiment of the invention, is that, while the single long vane of the second embodiment is not far from being in perfect balance (about the center of rotation of the flinger), with four equal vanes, each located radially at the same place on the flinger (albeit circumferentially at 90° spacing), the balance relationship is neutral. For example, the radial location of the leading edge  372  and the trailing edge  373  is at the same radius and of the same mass for each of the vane segments. The leading edge, or first end,  372  is located at a radius that is smaller than the trailing edge, or second end  373 . It can be appreciate that the spiral vane segments  74  extend arcuately between the first and second ends  372  and  373 , respectively. 
         [0037]    A flinger oil seal according to a fourth exemplary embodiment is depicted in  FIGS. 10A and 10B . In this embodiment, an axial facing flinger surface  477  of the flinger  440  is canted at an angle A with respect to the axially facing insert recess  463  formed into insert  460 . With rotation of the flinger  440 , relative to the centerline l of the shaft  11  upon which the flinger  440  mounts, the angled flinger surface  477  oscillates axially thus providing a pumping action in addition to the centrifugal force acting on oil, gas, and solid matter. The cyclic local pressure generated by the pumping action acts to force unwanted matter (oil, gas, and solid matter) through a discharge port  470  thus preventing said oil, gas, and solid matter from reaching the seal rings ( 46 ,  47 ). This oscillating flinger surface  477  acts in a manner similar to that of a piston-free swash plate, or swash plate pump. The oscillating face can be non-flat, in which case it would be a piston-free “cam” plate. 
         [0038]    In a fifth exemplary embodiment shown in  FIGS. 11A and 11B , spiral vane  90  is provided on the turbine-end heat shield  504 . On the turbine-end of the turbocharger, a piston ring  14  is located in the cylindrical surface of a piston ring boss  12  located between the turbine-end of the shaft and the back face of the turbine wheel  10 . In a manner opposite to that of the above embodiments, the spiral vane  90  has a leading edge  572  at a greater diameter than that of the trailing edge  573  to provide an increase in pressure towards the center of the heat shield  504  and towards the seal ring  14 . While the direction of flow and pressure is different within the context of the interaction between the rotating and static elements of a matched set, the logic for having a positive pressure differential toward the inside of the bearing housing is consistent for reducing flow of oil from the bearing housing to either the compressor or turbine stages and thus, ultimately, into the exhaust system. The spiral vane  90  is pressed into the material from which the turbine heat shield is fabricated. Since most turbine heat shields are stamped using the progressive stamping process, the addition of a stamped vane is a relatively simple modification to the tool. 
         [0039]    Accordingly, the flinger oil seal has been described with some degree of particularity directed to the exemplary embodiments. It should be appreciated; however, that the present invention is defined by the following claims construed in light of the prior art so that modifications or changes may be made to the exemplary embodiments without departing from the inventive concepts contained herein.