Abstract:
A valve rotator for use in an internal combustion engine. The valve rotator including a plurality of retention members, each able to removeably and rotateably couple the stationary housing to the rotating body. The plurality of retention members are defined by a plurality of recesses allowing each of the plurality of retention members to deflect with respect to the stationary housing. The retention members allow the rotating body to be removed from the stationary housing without the need for permanently damaging the stationary housing (e.g. during rebuilding). Additionally, the retention members may be incorporated on housings that have undergone heat treatment processes without rendering the housings susceptible to cracking or damage.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to valve rotators for internal combustion engines, and more specifically to valve rotators with snap fit housings. 
       BACKGROUND 
       [0002]    During operation, the cylinders of large internal combustion engines often create a heat gradient from the relatively cool intake side of the cylinder and the relatively hot exhaust side of the cylinder. This heat gradient may cause warping of the intake and exhaust valves if the gradient becomes too intense, thereby accelerating wear and potentially damaging the valves and valve seats. To combat these effects, valve rotators are commonly installed to rotate the valves during engine operation, which results in the valves being subjected to a more even distribution of heat. Rotation of the valve also provides a more even wear pattern for the valve and valve seat. 
         [0003]    Valve rotators are frequently constructed in two parts, a housing that engages and is fixed relative to an end of the valve spring(s), and a body coupled to the valve stem. For every reciprocating movement of the valve, the body and the valve together rotate a small amount relative to the housing. 
         [0004]    For higher performance and enhanced durability, valve springs are becoming increasingly hard and stiff. In response, the housing of the valve rotator assembly must also be hardened to resist premature wear on the surfaces of the housing that contact the spring. As a result of this hardening, the housing also becomes increasingly brittle and prone to cracking when worked. This issue is particularly troublesome in valve rotator assemblies in which an edge surface of the housing is cold rolled over a portion of the rotator body to form a locking bead that secures the two components together. Many times, the addition of the locking bead to a hardened housing by cold forming results in the part being cracked and/or rendered unusable. 
       SUMMARY 
       [0005]    In some embodiments, the invention provides a valve rotator assembly for rotating an internal combustion engine valve about an axis in response to reciprocating movement of the valve. The assembly includes a body for coupling to a portion of the valve and including a retention surface. The assembly also includes a housing that removably and rotatably receives the body. The housing includes a bottom wall and a plurality of resilient members that engage the retention surface to removably couple the body to the housing. The assembly also includes a rotary advance mechanism that engages the body and the housing to rotate the body relative to the housing. 
         [0006]    In some embodiments, the invention provides a method of assembling a valve rotator for rotating a valve of an internal combustion engine about an axis. The method includes providing a housing including a plurality of resilient members and a body for coupling with the valve and including a retention surface. Components of a rotary advance mechanism are positioned between the housing and the body, and the body is positioned for insertion into the housing. The body is axially inserted into the housing, which includes engaging the body with the resilient members to thereby urge the resilient members away from a relaxed position. The retention surface is moved axially beyond the resilient members, which allows the resilient members to return to the relaxed position so as to retain the body within the housing. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]      FIG. 1  is a perspective view of a valve assembly for an internal combustion engine. 
           [0008]      FIG. 2  is a section view taken along line  2 - 2  of  FIG. 1 . 
           [0009]      FIG. 3  is an enlarged perspective view of the valve assembly of  FIG. 1 . 
           [0010]      FIG. 4  is a section view taken along line  4 - 4  of  FIG. 3 . 
           [0011]      FIG. 5  is an exploded view of the valve assembly of  FIG. 1 . 
           [0012]      FIG. 6  is a perspective view of a valve rotator assembly of the valve assembly of  FIG. 1 . 
           [0013]      FIG. 7  is a section view taken along line  7 - 7  of  FIG. 6 . 
           [0014]      FIG. 8  is an exploded view of the valve rotator assembly of  FIG. 6 . 
           [0015]      FIG. 9  is a section view taken along line  9 - 9  of  FIG. 8 . 
           [0016]      FIG. 10  is a perspective view of a rotator housing of the valve rotator assembly of  FIG. 6 . 
           [0017]      FIG. 11  is a section view taken along line  11 - 11  of  FIG. 10 . 
           [0018]      FIG. 12  is a perspective view of a rotator body of the valve rotator assembly of  FIG. 6 . 
           [0019]      FIG. 13  is a section view taken along line  13 - 13  of  FIG. 12 . 
       
    
    
     DETAILED DESCRIPTION 
       [0020]    It is to be understood that the invention is not limited in its application to the details of construction and the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. 
         [0021]      FIGS. 1-5  illustrate a valve assembly  8  for use in an internal combustion engine. The valve assembly  8  includes a valve rotator assembly  10  that supports a valve  12 . The valve rotator assembly  10  includes a rotator housing  14  that engages the end(s) of one or more valve springs  18   a,    18   b,  and a rotator body  22  received by and fitting generally within the rotator housing  14 . The rotator body  22  receives and engages a stem portion  26  of the valve  12  that generally defines a valve axis  28 . The rotator assembly  10  also includes a helical garter spring  30  that extends around and is received by an annular recess  98  defined by the rotator body  22 . The garter spring  30  also engages a spring washer  34  that fits between the garter spring  30  and an inner surface  51  of the housing  14 . The garter spring  30  and spring washer  34  together define a rotary advance mechanism that rotates the body  22  relative to the housing  14 . During engine operation, a valve actuation component (e.g., a cam lobe and/or a rocker arm, not shown) directly or indirectly applies a force to an upper surface  38  of the valve stem  26  to open the valve  12  (opening movement of the valve is in a generally downward direction with respect to  FIGS. 1-4 ). The valve spring(s)  18   a,    18   b  resist opening movement of the valve, thereby compressing the spring washer  34  and the garter spring  30  between the rotator housing  14  and the rotator body  22 . As the valve  12  returns to the closed position, the compressive forces between the valve spring(s)  18   a,    18   b  and the valve actuation component reduce. Actuation of the valve  12  in this manner causes the spring washer  34  and the garter spring  30  to cyclically compress and expand, which in turn causes the rotator body  22  and the valve  12  to rotate with respect to the rotator housing  14  in a known manner. 
         [0022]    With reference also to  FIGS. 6-11 , the rotator housing  14  includes a bottom wall  42  that engages the valve spring(s)  18   a,    18   b,  and an outer wall  46  extending around an outer circumference of the bottom wall  42  and generally perpendicularly away from the bottom wall  42 . The bottom wall  42  extends generally radially inwardly from the outer wall  46  and includes one or more spring seats  50   a,    50   b.  Each spring seat  50   a,    50   b  is shaped to retain a corresponding one of the valve springs  18   a,    18   b.  In the illustrated construction, the spring seats  50   a,    50   b  form concentric annular surfaces, with each annular surface sized to substantially correspond to the diameter of the valve spring  18   a,    18   b  it retains. The spring seats  50   a,    50   b  may also be formed on axially offset yet generally parallel planes to provide one or more retaining walls  58 . The retaining wall(s)  58  may be sized and shaped to provide radial stability to the valve springs  18   a,    18   b,  and to help properly locate the valve rotator assembly  10  relative to the valve springs  18   a,    18   b  during assembly. In alternate constructions, the one or more spring seats  50   a,    50   b  may be formed in a common plane and/or be formed as or by a recess in the rotator housing  14 . In still further constructions, there may only be a single engagement surface for the one or more valve springs  18   a,    18   b.  In yet another construction, the innermost valve seat  50   b  may be provided with an additional retaining wall corresponding to the inner diameter of the inner valve spring  18   b.    
         [0023]    The outer wall  46  defines a plurality of generally U-shaped recesses  62  that open at an upper edge  66  of the outer wall  46  and extend generally downwardly therefrom toward the bottom wall  42 . In the illustrated embodiment, the edges of the wall that define each recess  62  are filleted and/or radiused to reduce stresses along the outer wall  46  in the vicinity of the recesses  62 . 
         [0024]    The outer wall  46  includes a plurality of resilient retention members  70  (e.g., 4 in the illustrated construction) that extend substantially perpendicularly away from the bottom wall  42  between adjacent ones of the recesses  62 . The retention members  70  are configured to be radially deflectable relative to the remainder of the outer wall  46 , away from a relaxed position, during assembly and disassembly of the valve rotator assembly  10 . The retention members  70  are generally equally distributed about the circumference of the outer wall  46 . In the illustrated construction, each retention member  70  includes a distal end that extends beyond the upper edge  66  of the remainder of the outer wall  46 . The distal end extends radially inwardly relative to the remainder of the retention member  70  to form a retaining tip  74 . In alternate constructions the retaining tip  74  may be formed as a hook, or may include a distal end having a first, proximal portion that extends radially inwardly, and a second distal portion that extends radially outwardly. The retention members  70  and retaining tips  74  may include other forms and configurations that allow the rotator housing  14  to removeably and rotatably receive the rotator body  22 , as discussed below. 
         [0025]    In the illustrated embodiment, the rotator housing  14  is generally formed from sheet material by one or more stamping and/or drawing operations; however, alternate constructions may include the rotator housing  14  being forged, cast, machined, or various combinations of these to produce the desired shape. Additionally, the rotator housing  14  is generally formed from a metal (e.g. steel) and is preferably heat treated, induction hardened, case hardened, shot peened or otherwise materially treated to enhance the wear characteristics of the rotator housing  14 . In certain embodiments, the rotator housing  14  is formed of a low carbon (0.05-0.15% carbon) or a mild carbon (0.16-0.29% carbon) steel. Two specific examples of suitable carbon steels are AISI 1008 and AISI 1010, which are malleable enough to stamp but include sufficient carbon content for controlled hardening after forming. Although the final surface hardness of the rotator housing  14  depends upon the specific material used and whether and to what extent the rotator housing  14  is hardened, some non-hardened embodiments of the rotator housing  14  include a surface hardness of at least about 107 HK (Knoop hardness). Other embodiments of the rotator housing  14 , which are generally hardened in some manner, include a surface hardness of at least about 402 HK, while still other embodiments of the rotator housing  14  include a surface hardness of at least about 510 HK. Furthermore, some embodiments of the rotator housing, also generally hardened, include a surface hardness up to about 776 HK, while other embodiments of the rotator housing  14  are hardened to include a surface hardness up to about 630 HK, and other embodiments of the rotator housing  14  are hardened to include a surface hardness up to about 576 HK. Still other embodiments of the rotator housing  14 , which are also generally hardened, include a surface hardness in the range of about 402 HK to about 776 HK, while other embodiments of the rotator housing  14  include a surface hardness in a range of about 510 HK to about 630 HK. One preferred embodiment of the rotator housing  14  is hardened to include a surface hardness in a range of about 510 HK to about 576 HK. 
         [0026]    The retention members  70  are configured to deflect radially outwardly as the rotator body  22  is inserted into or withdrawn from the rotator housing  14 . When the rotator body  22  is fully received within the rotator housing  14 , the retention members  70  return to their original positions, and do not restrict relative rotation between the rotator body  22  and the rotator housing  14 . Similarly, when the rotator body  22  is fully withdrawn from the rotator housing  14 , the retention members  70  return to their original positions such that the rotator housing  14  may be reused with a different (e.g., a new or rebuilt) rotator body  22  and/or a new or replacement garter spring  30  and spring washer  34 . 
         [0027]    While the illustrated retention member is substantially uniform in cross section and has a length nearly equal to the height of the outer wall  42 , alternate constructions may include a retention member  70  that extends axially and inwardly directly from the upper edge  66  of the outer wall  42 . In still other constructions, the retention member  70  may extend only partially toward the upper edge  66  of the outer wall  42 . Alternate constructions may further include retention members  70  differing in width and or cross section along their length. 
         [0028]      FIGS. 12 and 13  illustrate the rotator body  22  in further detail. The rotator body  22  is removeably and rotateably received by the rotator housing  14  and includes a main body  78 , a secondary body  82  extending radially outwardly from the main body  78 , and a central recess  86  extending axially through the rotator body  22  and shaped to receive the valve stem  26 . 
         [0029]    The main body  78  of the rotator body  22  is substantially cylindrical and defines the central recess  86 . The main body  78  includes a first outer diameter  88  and a second outer diameter  90 . The first outer diameter  88  is sized to fit within the innermost diameter of the bottom wall  42  of the rotator housing  14 , and extends a first axial distance. The second outer diameter  90  is sized to fit within an inner diameter  36  of the spring washer  34 , and extends a second axial distance. In the illustrated construction, the combined first and second distances substantially define the height of the main body  78 . 
         [0030]    The secondary body  82  extends radially outwardly from the main body  78  and defines a third outer diameter  94  that fits within the outer wall  46  while allowing sufficient clearance to allow relative rotation between the rotator housing  14  and the rotator body  22 . The secondary body  82  also defines an annular recess  98  shaped to receive the garter spring  30 , an angled lead-in surface  102  that engages the retention members  70  during assembly of the rotator assembly  10 , and a retention surface  106  that engages the retention members  70  during disassembly of the rotator assembly. In the illustrated embodiment, the secondary body  82  includes a substantially flat upper surface  110 , however, in alternate constructions; the upper surface  110  may be contoured to provide additional strength or perform other functions, as necessary. In still other constructions, the flat upper surface  110  may itself define the retention surface  106 . 
         [0031]    The annular recess  98  is defined by the secondary body  82  and is shaped to receive the garter spring  30  (described below). In the illustrated construction, the annular recess  98  opens axially toward the main body  78 , is defined by a bottom surface  114 , and includes a substantially semi-circular cross-section. Alternate cross-sections may be utilized to facilitate the outer contour of different types of garter springs  30 . In some constructions, the annular recess  98  may define a plurality of ridges or ribs (not shown) that engage the garter spring  30  and facilitate rotation of the rotator body  22  relative to the rotator housing  14 . In still other constructions, the annular recess  98  may be lined with a deformable material (e.g. rubber), also to facilitate rotation of the rotator body  22  with respect to the rotator housing  14 . 
         [0032]    The lead-in surface  102  defines a chamfer between the third outer diameter  94  and the bottom surface  114  of the rotator body  22 . When the rotator body  22  is inserted into the housing  14 , the lead-in surface  102  engages the retention members  70  and urges the retention members  70  radially outwardly. In the illustrated embodiment, the lead-in surface  102  extends completely around the third outer diameter  94 . In alternate embodiments, the rotator body  22  may include a plurality of radially spaced apart lead-in surfaces  102 , each positioned for alignment with a respective one of the retention members  70  during assembly. In still other embodiments, there may be no discernable chamfer or radius between the bottom surface  114  and the third outer diameter  94 , in which case the bottom surface  114  itself defines the lead-in surface. 
         [0033]    In the illustrated construction, the retention surface  106  is formed as a radius between the third outer diameter  94  and the upper surface  110  of the rotator body  22 , and facilitates retention of the rotator body  22  with respect to the rotator housing  14 . The retention surface  106  extends completely around the third outer diameter  94 . In alternate embodiments, the corner defined by the junction of the upper surface  110  and third outer diameter  94  may not be radiused, in which case the upper surface  110  will itself defined the retention surface  106 . In yet another embodiment, the retention surface  106  may be in the form of a chamfer between the upper surface  110  and the third outer diameter  94 , and may bias the retention members  70  radially outwardly during removal of the body  22  from the housing  14 . 
         [0034]    The central recess  86  is substantially concentric with the axis  28  and extends axially through the rotator body  22 . The central recess  86  includes a first portion  118  and a second portion  122 . The first portion  118  extends generally from the upper surface  110  a first distance into the rotator body  22  at a first wall angle. The second portion  122  generally extends from the first portion  118  a second distance into the rotator body  22  at a second, steeper wall angle. The second portion  122  defines a frusto-conical surface  123  configured to receive and capture a set of tapered valve collets  126  (see  FIG. 5 ). In alternate embodiments, the central recess  86  may include additional portions each including a different wall angle, or may be formed from a single portion having a single wall angle. 
         [0035]    In the illustrated embodiment, the rotator body  22  is generally formed from a single piece of metallic material (e.g., steel) and may be heat treated and/or hardened as necessary to improve durability. The rotator body  22  may be forged, stamped, cast, machined, formed of powdered metal, or any combination of these to produce the required shape. 
         [0036]    Referring again to  FIGS. 6-9 , the rotator housing  14  receives the spring washer  34  which engages the inner wall  51  of the rotator housing  14 . The spring washer  34  is slightly frusto-conical in profile, includes an annular depression  130  that receives the garter spring  34 , and defines an inner diameter  36 . The spring washer  34  may be formed from any suitable deformable and elastic material (e.g., spring steel). During operation the spring washer  34  deflects into a substantially flat, annular configuration upon application of an axial compressive force between the housing  14  and the body  22 . 
         [0037]    In the illustrated construction the annular depression  130  is a smooth, concave groove extending completely around the spring washer  34  and shaped to receive the garter spring  30 . In alternate constructions, the annular depression  130  may include a plurality of ridges or ribs, or may be lined with a deformable material (e.g., rubber) to assist the garter spring  30  in rotating the rotator body  22  with respect to the rotator housing  14 . 
         [0038]    The annular recess  98  receives the garter spring  30 , which in turn engages the spring washer  34 . Although illustrated schematically in the drawings as an annular ring, as understood by those skilled in the art, the garter spring  30  is a relatively tightly wound helical coil spring having a length that substantially corresponds to the circumference of the annular recess  98 . The garter spring  30  is substantially circular in cross-section and its coils deflect when subjected to an axial load. In some constructions, the garter spring  30  may be filled or coated with a deformable material (e.g., rubber) to provide additional vertical support under load and/or to assist in returning the garter spring  30  to its initial position. 
         [0039]    The valve rotator assembly  10  can be assembled as a unit and transported to an engine manufacturing or rebuilding facility for installation. During assembly, the spring washer  34  is positioned in the rotator housing  14  against the inner surface  51 . The garter spring  30  is positioned in the annular recess  98  and the rotator body  22  is axially inserted into the rotator housing  14 . During such insertion the retaining tips  74  of the retention members  70  contact the lead-in surface  102  and deflect radially outwardly until the retaining tips  74  snap over the retention surface  106 . When the rotator body  22  is completely received by the rotator housing  14 , the garter spring  30  and spring washer  34  are captured therebetween. Once assembled, the completed rotator assembly  10  may be installed in a valve train of an engine, or shipped as a unit to a manufacturing or rebuilding facility. 
         [0040]    To install the completed valve rotator assembly  10  in the valve train of an engine, the assembly  10  is positioned so the valve seat(s)  50   a,    50   b  of the rotator housing  14  engage the end(s) of the valve spring(s)  18   a,    18   b.  The valve stem  26  is inserted through a valve guide in the cylinder head (not shown), and into the central recess  86 . The valve springs  18   a,    18   b  are compressed to expose the end of the valve stem  26  such that the collets  126  can be installed thereabout. The valve springs  18   a,    18   b  are released and the collets  126  move into engagement with the angled surface  123  of the rotator body  22 , which biases the collets  126  into engagement with the end of the valve stem  26  to secure the valve  12  to the valve rotator  10 . 
         [0041]    In operation, a valve train component operates to open the valve  12  by moving the valve stem  26  axially against the biasing force of the valve spring(s)  18   a,    18   b.  The valve stem  26  in turn moves the rotator body  22  due to engagement between the valve collets  126  and the frusto-conical surface  123 . The garter spring  30  and spring washer  34  are thereby compressed between the rotator body  22  and the rotator housing  14 . When the valve train component operates to close the valve, at least some of the compressive forces applied to the garter spring  30  and spring washer  34  are reduced, thereby allowing the garter spring  30  and spring washer  34  to at least partially return toward a relaxed configuration. This cycling of compression and relaxation of the garter spring  30  and spring washer  34  rotates the rotator body  22  and valve  12  relative to the rotator housing  14  in a known manner. 
         [0042]    The resilient retention members  70  allow the valve rotator assembly  10  to be disassembled and rebuilt without damaging or permanently (e.g., plastically) deforming the body  22  or the housing  14 . To disassemble the valve rotator  10 , the rotator body  22  is pressed or otherwise withdrawn axially from the rotator housing  14 , causing the retention surface  106  to engage the retaining tips  74 , and urging the retention members  70  radially outwardly. Once the rotator body  22  has been removed from the housing  14 , the retention members  70  elastically return to their original positions. The various parts of the assembly  10  may then be inspected and/or replaced, if necessary. The garter spring  30  and/or the spring washer  34  are the components most likely to require replacement. The various parts may then be re-assembled as described above and returned to service. 
         [0043]    The resilience of the retention members  70  provides a rotator housing structure  14  that affords a snap fit between the rotator body  22  and the rotator housing  14  even when the housing  14  material is significantly hardened. The radiused geometry of the recesses  62  functions to distribute stresses that might otherwise lead to fractures when the retention members  70  deflect during assembly and disassembly of the valve rotator assembly  10 . 
         [0044]    Although the foregoing disclosure has been directed generally to valve rotator assemblies including a garter spring and spring washer rotary advance mechanism, it should be appreciated that the teachings herein may also be incorporated into other valve rotators having other rotary advance mechanisms, such as valve rotators that utilizes various combinations of springs, ball bearings, wedges, and other known structures that provide relative rotation between the rotator body  22  and the rotator housing  14  during actuation of the valve  12 .