Abstract:
A planetary pin for use in a planetary gear system is provided. The planetary pin comprises a cylindrical body, a first end, an axial passage extending from the first end, and a wall thickness between the axial passage and an outer surface of the body. A cylindrical lateral passage is formed through the wall thickness axially displaced from the first end and in fluid communication with the axial passage. A slot formed in the first end from the outer surface to intersect with the axial passage. A planetary pin assembly using the planetary pin is provided in which the slot in the first end of the pin cooperates with a planetary carrier to accept and direct lubricant to the lateral passage through the axial passage.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. patent application Ser. No. 61/993,027 filed on May 14, 2014, which is incorporated by reference as if fully set forth. 
     
    
     FIELD OF INVENTION 
       [0002]    Embodiments of the present invention generally relate to planetary gear systems using planetary bearings in power transmission mechanisms. More specifically, embodiments of the present invention relate to a planetary pin for delivering lubricating fluids to a planetary gear and a planetary pin assembly using same. 
       BACKGROUND 
       [0003]    Some power transmission mechanisms, for example automotive transmissions, employ planetary gearsets requiring lubrication for reliable operation and thermal stability. In some transmissions, planet pins have fluid passages drilled through the pin body to deliver a lubrication fluid, for example oil, from a source such as an “oil dam” or a “lube catcher” to a raceway of a planetary bearing during operation. The flow of the oil requires rotation of the planetary gear carrier to generate centrifugal head to push the oil into the planet pin fluid passages. 
         [0004]    Current planetary gear systems may include a planet pin having a lubrication port formed through the pin wall to provide a flow of oil. The lubrication port may be fed with lubricant from a passage formed at an acute angle with the longitudinal axis of the planet pin. Drilling at an angle through bearing-grade steel can be a multi-step and complicated drilling operation. Therefore a need exists for a more easily manufactured planet pin. 
         [0005]    In other known pins, the lubrication port may be the opening of a radial passage in fluid communication with an axial passage. An oil dam or lube catcher directs an oil flow into and through the axial passage and radial passage. 
         [0006]    Axial space is at a premium in modern automotive transmission applications. Current planet pins utilize drilled radial holes as lubrication ports to supply the oil into the planet pin, or as features used to fix the pin in the planetary carrier which can increase the overall axial length of the planet pin. 
         [0007]    Accordingly, a need exists for an improved planet pin for use in a planetary gear system. 
       SUMMARY 
       [0008]    Embodiments of a planet pin for use in a planetary gear system and a planetary pin assembly using the planetary pin are provided. In one embodiment, the planetary pin comprises a cylindrical body having an outer surface, a first end, an inner surface defining an axial passage extending from the first end, and a wall thickness between the inner surface forming the axial passage and the outer surface. A cylindrical lateral passage is formed through the wall thickness in fluid communication with the axial passage. A slot is formed in the first end from the outer surface and intersecting with the axial passage. 
         [0009]    In one embodiment, a planetary pin assembly comprises a planetary carrier having a body including a planetary pin receptacle formed as a blind hole and an oil feed extending radially from a center of the body to the planetary pin receptacle adjacent to a bottom of the blind hole. The assembly further comprises a planetary pin with a cylindrical body having an outer surface, a first end, an inner surface defining an axial passage extending from the first end, and a wall thickness between the inner surface forming the axial passage and the outer surface. A cylindrical lateral passage is formed through the wall thickness in fluid communication with the axial passage. A slot is formed in the first end from the outer surface and intersecting with the axial passage. The bottom of the blind hole, the first end of the planetary pin, and a portion of a wall defining the blind hole form a plenum for receiving and directing an oil flow from the center of the body to the axial passage. 
         [0010]    Other and further embodiments of the present invention are described below. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    Embodiments of the present invention, briefly summarized above and discussed in greater detail below, can be understood by reference to the illustrative embodiments of the invention depicted in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments. 
           [0012]      FIG. 1  is a perspective view of a planetary pin in accordance with an embodiment of the present invention. 
           [0013]      FIG. 2  is an end view of the planetary pin according to  FIG. 1 . 
           [0014]      FIG. 3A  is a side cross sectional view of the planetary pin of  FIG. 1   
           [0015]      FIGS. 3B and 3C  are first end and second end views of the planetary pin of  FIG. 1 . 
           [0016]      FIG. 4  is a partial sectional side view of a portion of a planetary pin assembly in accordance with an embodiment of the present invention. 
           [0017]    To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common in the figures. The figures are not drawn to scale and may be simplified for clarity. It is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation. 
           [0018]    While described in reference to an automotive transmission, the present invention may be modified for a variety of applications while remaining within the spirit and scope of the claimed invention, since the range of the potential applications is great, and because it is intended that the present invention be adaptable to many such variations. 
       
    
    
     DETAILED DESCRIPTION 
       [0019]      FIG. 1  depicts a perspective view of a planet pin  100  in accordance with an embodiment of the present invention. The pin has a generally cylindrical body  102  with an outer surface  104  and a first end  106  with a first end surface  108 . The cylindrical body  102  has an axial passage  110  extending from the first end  106  as may be seen in the end view illustrated in  FIG. 2 . The axial passage  110  is generally concentric with the longitudinal axis  304  ( FIG. 3 ) of the planetary pin  100 . A generally cylindrical inner surface  112  defines the circumferential bounds of the axial passage  110 . The axial passage  110  may be formed by any suitable process, such as drilling. The cylindrical inner surface  112  of the axial passage  110  and the outer surface  104  form the bounds of wall thickness  116 . The planetary pin may be formed from any material suitable for supporting a bearing, for example bearing-grade steel. 
         [0020]    A generally cylindrical lateral passage  118  is formed through the wall thickness  116  at a location offset from the first end  106  along a longitudinal axis  304  ( FIG. 3 ) and in fluid communication with the axial passage  110 . The lateral passage  118  may be formed by any suitable process, for example drilling. In the embodiment illustrated in  FIG. 3 , the lateral passage  118  is formed so that the axis  302  of the lateral passage  118  is perpendicular to the longitudinal axis  304  of the planetary pin  100 . In other embodiments, the axis  302  may oriented at an acute angle with the longitudinal axis  304 . 
         [0021]    The axis  302  of the lateral passage  118  may extend along a radius of the planetary pin  100  and terminate in the axial passage  110  as illustrated in  FIG. 3 . In an embodiment, the lateral passage  118  may extend along a diameter through the wall thickness  116  and the axial passage  110 , and at least partially through the wall thickness  116  on the opposite side of the axial passage  110  (not shown). In other embodiments, the lateral passage  118  may be formed on a chord of the circular cross section of the cylindrical body  102  that does not intersect with the longitudinal axis  304 . 
         [0022]    A slot  120  is formed in the first end  106  of the planetary pin  100  from the outer surface  104  towards the axial passage  110  so that the slot  120  and the axial passage  110  are in fluid communication. In the embodiment illustrated in  FIG. 3 , slot  120  is a radial slot formed so that the axis  306  of the slot  120  intersects with axis  304  of the axial passage  110 . In other embodiments, the axes  304 ,  306  need not intersect in order for the axial passage  110  and the slot  120  to be in fluid communication. The axis  306  of the slot  120  may be rotationally offset from the axis  302  of the lateral passage  118  about the longitudinal axis  304 . In the non-limiting embodiment of  FIG. 3 , the slot  120  is rotationally offset form the lateral passage  118  by about 180 degrees (i.e., the axes  306  and  302  are rotationally offset by about 180 degrees). 
         [0023]    The slot  120  may extend beyond the axial passage  110  and may, in some embodiments, be formed along a diameter through the wall thickness  116  and the axial passage  110 , and at least partially through the wall thickness  116  on the opposite side of the axial passage  110 . Thus, the slot  120  may be a through slot (not shown). 
         [0024]    In one embodiment, the second end  114  of the planetary pin  100  includes a fixing slot  308  formed through the diameter of the planetary pin  100 . In some embodiments, the axis  310  of the fixing slot  308  is parallel with the axis  306  of the slot  120  as illustrated in  FIG. 3 . In other embodiments, the axes  306 ,  310  are not parallel. 
         [0025]    In the embodiment illustrated in  FIG. 3 , the second end  114  include an orientation slot  312  formed in the second end  114  through a second end surface  314  from the outer surface  104  to the fixing slot  308 . As illustrated, the orientation slot  312  may extend beyond the orientation slot  312  and may pass completely through the cylindrical body  102 . 
         [0026]      FIG. 4  depicts a planetary pin assembly  400  including a planetary carrier  402  and a planetary pin  100 . The planetary carrier  402  includes a body  404  including a planetary pin receptacle  406 . The planetary pin receptacle  406  in the embodiment of  FIG. 4  is formed as a blind hole having a bottom  408  and a cylindrical side wall  410  defining the blind hole. A lubricant feed channel, oil feed  412 , extends radially from a lubricant supply  416  centrally located in the body  404  proximate to the axis of rotation  414  of the body  404  to the planetary pin receptacle  406  adjacent to the bottom  408  of the blind hole forming the planetary pin receptacle  406 . The oil feed  412  is in fluid communication with the planetary pin receptacle  406 . 
         [0027]    In the planetary pin assembly illustrated in  FIG. 4 , the planetary pin  100  is inserted into the planetary pin receptacle  406  with the first end  106  leading into the planetary pin receptacle  406  such that a portion of the first end surface  108  abuts against the bottom  408  with the slot  120  aligned with the oil feed  412 . The bottom  408 , a portion of the cylindrical side wall  410 , and the first end  106  of the planetary pin  100  form a plenum  418  in fluid communication with the axial passage  110 . A lubricant, for example oil, supplied by the oil feed  412  is received in the plenum  418  and directed to the axial passage  110  and through the lateral passage  118  to lubricate a bearing  420  disposed on the planetary pin  100 . 
         [0028]    A portion of the body  404  spaced apart from the bottom  408  includes a flange  422  including a passage  424  formed through a first portion  422   a  and at least partially through the second portion  422   b.  When installed in a preferred orientation, the fixing slot  308  at the second end  114  of the planetary pin  100  is aligned with the passage  424 . A fixing pin, for example a roll pin or dowel pin, may be disposed through the portion of the passage  424  formed in flange first portion  422   a  and pass through the fixing slot  308  and received at least partially into the second portion  422   b.  At least one of the first and second portions  422   a  and  422   b  are sized to accept the fixing pin in an interference fit and the fixing slot  308  receives the fixing pin with clearance to minimize the rotation of the installed planetary pin  100  about the longitudinal axis  304 . 
         [0029]    The inventors have noted that by creating a slot  120  at the first end  106  of the planetary pin  100  to form a plenum  418  when the pin is installed in the planetary carrier  402 , the length of the pin may advantageously be reduced. Typical planetary pins require a full wall around the ports used to provide lubrication to the planetary bearing. By eliminating one wall of the lubricant supply passage to the pin, the pin length is reduced by approximately one wall thickness. 
         [0030]    A similar benefit is realized at the second end  114  of the planetary pin  100 . Typical planetary pins require a full wall around the passages used to receive a fixing pin to fix the planetary pin against undesirable rotation. The inventors have noted that by providing a slot in the second end  114 , the planetary pin axial length can be reduced by approximately one wall thickness. 
         [0031]    Further benefits are realized in that each passage formed in the pin, axial passage  110 , lateral passage  118 , and slot  120 , are formed normal to a surface of the planetary pin  100 , avoiding complicated machining operations such as angled drilling through the cylindrical body  102  of the planetary pin  100 . 
         [0032]    Thus a planetary pin and a planetary pin assembly are provided herein. The inventive planetary pin and planetary pin assembly may advantageously have a reduced axial length compared to some known planetary pins and planetary pin assemblies. The inventive pin may also eliminate complicated machining operations in production of the pin, beneficially reducing manufacturing costs.