Abstract:
A bushing for taking up the gap between a support bolt and a rocker arm shaft in an internal combustion engine in order to eliminate unwanted motion and subsequent engine noise.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This Application claims priority under 35 U.S.C. §119(e) from earlier filed U.S. Provisional Applications Ser. No. 62/200017, filed Aug. 1, 2015; Ser. No. 62/284859, filed Oct. 13, 2015; Ser. No. 62/272070, filed Dec. 29, 2015, Ser. No. 62/275210, filed Jan. 5, 2016; Ser. No. 62/276821, filed Jan. 8, 2015; 62/276866, filed Jan. 10, 2016; Ser. No. 62/278413, filed Jan. 13, 2016; Ser. No. 62/310791, filed Mar. 20, 2016; Ser. No. 62/358031, filed Jul. 3, 2016. The entirety of all the above-listed provisional applications are incorporated herein by reference. 
     
    
     BACKGROUND 
       [0002]    Technical Field 
         [0003]    The present device is in the field of internal combustion engines, particularly the valve train components of such engines. 
         [0004]    Summary 
         [0005]    In a typical motorcycle engine, for example, the rocker assembly includes a rocker arm support that holds a rocker arm shaft. A rocker support bolt secures the rocker arm support and also cross-pins the rocker arm shaft in place. However, in some engines, there can be excessive clearance between the rocker support bolt and the rocker arm shaft. This can cause a loud tapping noise at higher rpms. 
         [0006]    A round bushing placed on the rocker support bolt can take up this space and eliminate the tapping caused by the rocker arm shaft hitting the bolt. However, some bushings can be compressed and deformed during installation rather than push down into the hole. Although bushings made of more malleable materials can have the advantage of compressing during installation and then restoring to a relaxed state to expand and fill the space, they, too, can be subject to undesirable deformation on installation. Further the rocker support plate can have a casting parting ring around the circumference of the hole, which can increase the flaring problem. This can lead to problems of alignment and valve train geometry. 
         [0007]    Substantially cylindrical bushings can address this issue, but must be precisely machined to fit both bolts and rocker plate holes, which can be expensive to produce. Non-cylindrical bushings, though, can fit a wide variety of bolt/plate combinations. What is needed is an improved bushing for a rocker support bolt to properly align and lock the rocker arm shaft, that is easy to install and can fill the clearance space while withstanding temperatures of engine operation 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    Further details of the present device are explained with the help of the attached drawings in which: 
           [0009]      FIG. 1 a    depicts an exploded perspective view of a rocker arm support assembly of a typical engine. 
           [0010]      FIG. 1 b    depicts an exploded side view of the rocker arm support assembly shown in  FIG. 1   a.    
           [0011]      FIG. 1 c    depicts a detail cutaway side view of the support bolt insertion point on the rocker arm support assembly shown in  FIG. 1   a.    
           [0012]      FIG. 2 a    depicts a perspective view of one embodiment of the present device. 
           [0013]      FIG. 2 b    depicts a perspective view of an alternate embodiment of the present device as shown in  FIG. 2   a.    
           [0014]      FIG. 3 a    depicts a perspective view of one embodiment of the present device. 
           [0015]      FIG. 3 b    depicts a perspective view of an alternate embodiment of the present device as shown in  FIG. 3   a.    
           [0016]      FIG. 4 a    depicts a perspective view of one embodiment of the present device. 
           [0017]      FIG. 4 b    depicts a perspective view of an alternate embodiment of the present device shown in  FIG. 4   a.    
           [0018]      FIG. 5 a    depicts a perspective view of one embodiment of the present device. 
           [0019]      FIG. 5 b    depicts a perspective view of an alternate embodiment of the present device shown in  FIG. 5   a.    
           [0020]      FIG. 6 a    depicts a perspective view of one embodiment of the present device. 
           [0021]      FIG. 6 b    depicts a perspective view of an alternate embodiment of the present device shown in  FIG. 6   a.    
           [0022]      FIG. 7 a    depicts a perspective view of one embodiment of the present device. 
           [0023]      FIG. 7 b    depicts a perspective view of an alternate embodiment of the present device shown in  FIG. 7   a.    
           [0024]      FIG. 8 a    depicts a perspective view of one embodiment of the present device. 
           [0025]      FIG. 8 b    depicts a perspective view of an alternate embodiment of the present device shown in  FIG. 8   a.    
           [0026]      FIG. 9 a    depicts a perspective view of one embodiment of the present device. 
           [0027]      FIG. 9 b    depicts a perspective view of an alternate embodiment of the present device shown in  FIG. 9   a.    
           [0028]      FIG. 10 a    depicts a perspective view of one embodiment of the present device. 
           [0029]      FIG. 10 b    depicts a perspective view of an alternate embodiment of the present device shown in  FIG. 10   a.    
       
    
    
     DETAILED DESCRIPTION 
       [0030]      FIG. 1 a    depicts an exploded perspective view of a rocker arm support assembly of an engine. A rocker arm support  102  can have a plurality of bolts  104  securing a rocker arm support  102  and a rocker arm shaft  105 . As shown in  FIG. 1   a,  some embodiments of the present device can be a bushing  106  having an inner surface and an outer surface, and a distal end and a proximal end. In some embodiments the inner diameter of a bushing  106  can be such to selectively engage longitudinally with a bolt  104  passing through it, but in other embodiments can be any other known and/or convenient diameter. In the embodiment shown in  FIG. 1   a,  a bushing  106  can be substantially cylindrical, or have a substantially longitudinally constant outer diameter, but in other embodiments can have a longitudinally varying outer diameter. In some embodiments a bushing  106  can be fabricated from steel or any other known and/or convenient material, and can be hardened, spring-tempered, or subject to any other known and/or convenient process. In some embodiments, a spring-tempered material can be advantageous to maintain device performance during heat expansion. 
         [0031]      FIG. 1 b    depicts an exploded side view of the rocker arm support assembly shown in  FIG. 1   a.  In some embodiments, a bolt  104  can pass through a bushing  106 , where they can selectively engage into a designated hole in a rocker arm support  102 . 
         [0032]      FIG. 1 c    depicts a detail cutaway side view of the support bolt insertion point on the rocker arm support assembly shown in  FIG. 1  a. As a bolt  104  engages with a rocker arm support  102 , a bolt  104  can also align with a notch in a rocker arm shaft  105 , locking it in place. In some embodiments, a bushing  106  can occupy the clearance space between a bolt  104 , a rocker arm support  102 , and a rocker arm shaft  105 , thereby tightening the fit. 
         [0033]    In the embodiment shown in  FIG. 2 a   , a bushing  106  can have sections of longitudinally varying outer diameter. In some embodiments, the distal end of a bushing  106  can have an outer diameter less than that of the proximal end. As shown in  FIG. 2 a   , a bushing  106  can have a tapered geometry, but in other embodiments can have any other known and/or convenient geometry. 
         [0034]      FIG. 2 b    depicts an alternate embodiment of the present device as shown in  FIG. 2 a   , in which a bushing  106  can have a longitudinal slit  202 . In some embodiments a longitudinal slit  202  can run along the entire length of a bushing  106 , but in other embodiments can run longitudinally along any known and/or convenient segment of a bushing  106 . 
         [0035]      FIG. 3 a    depicts another embodiment of the present device in which a bushing  106  can have sections of longitudinally varying diameter. In the embodiment of  FIG. 3 a   , a bushing  106  can have a first segment  204  with a larger diameter than that of at least one second segment  206 . In some embodiments, a first segment  204  can be located at the proximal end of a bushing  106 , with at least one second segment  206  at the distal end, but can have any other known and/or convenient configuration in other embodiments. 
         [0036]      FIG. 3 b    depicts an alternate embodiment of the present device as shown in  FIG. 3 a   , in which a bushing  106  can have a longitudinal slit  202 . In some embodiments a longitudinal slit  202  can run along the entire length of a bushing  106 , but in other embodiments can run longitudinally along any known and/or convenient segment of a bushing  106 . In the embodiment shown in  FIG. 3 b   , fabricating a bushing  106  from a spring-tempered material can improve device performance by allowing a bushing  106  to maintain pressure against a rocker arm shaft  105  even as a rocker assembly expands due to heat. 
         [0037]      FIG. 4 a    depicts a perspective view of another embodiment of the present device, in which a bushing  106  can have sections of longitudinally varying outer diameter. In some embodiments, the distal end and the proximal end of a bushing  106  can each have an outer diameter less than that of a region substantially at the longitudinal midpoint of a bushing  106 . As shown in  FIG. 4 a   , a bushing  106  can have a double-tapered geometry substantially symmetric about the longitudinal midpoint of a bushing  106 , but in other embodiments can have any other known and/or convenient geometry. 
         [0038]      FIG. 4 b    depicts an alternate embodiment of the present device as shown in  FIG. 4 a   , in which a bushing  106  can have a longitudinal slit  202 . In some embodiments a longitudinal slit  202  can run along the entire length of a bushing  106 , but in other embodiments can run longitudinally along any known and/or convenient segment of a bushing  106 . 
         [0039]      FIG. 5 a    depicts another embodiment of the present device in which a bushing  106  can have sections of longitudinally varying diameter. In the embodiment of  FIG. 5 a   , a bushing  106  can have a first segment  204  with a larger diameter than that of at least one second segment  206 . In some embodiments, a first segment  204  can be located substantially at the longitudinal midpoint of a bushing  106 , with a second segments  206  of at the proximal and the distal end, but can have any other known and/or convenient configuration in other embodiments. In some embodiments, second segments  206  can be of substantially equal length, but in other embodiments can be of any other known and/or convenient lengths. 
         [0040]      FIG. 5 b    depicts an alternate embodiment of the present device as shown in  FIG. 5 a   , in which a bushing  106  can have a longitudinal slit  202 . In some embodiments a longitudinal slit  202  can run along the entire length of a bushing  106 , but in other embodiments can run longitudinally along any known and/or convenient segment of a bushing  106 . 
         [0041]      FIG. 6 a    depicts a perspective view of another embodiment of the present device. In some embodiments, a bushing  106  can have a non-circular cross section with a plurality of longitudinal grooves  602  adjacent to longitudinal ridges  604 . As shown in  FIG. 6 a   , longitudinal grooves  602  and longitudinal ridges  604  can have a rounded cross sections, but in other embodiments can have any other known and/or convenient cross-sectional geometry. 
         [0042]      FIG. 6 b    depicts an alternate embodiment of the present device as shown in  FIG. 6 a   , in which a bushing  106  can have a longitudinal slit  202 . In some embodiments a longitudinal slit  202  can run along the entire length of a bushing  106 , but in other embodiments can run longitudinally along any known and/or convenient segment of a bushing  106 . 
         [0043]    As shown in  FIG. 7 a   , other embodiments of the present device can have at least one portion of the outer surface extruded to form at least one circumferential ridge  702 , which can be located substantially at the longitudinal midpoint of a bushing  106 . However, circumferential ridges  702  can be located at any other known and/or convenient point on the outer surface of a bushing  106 . In the embodiment of  FIG. 7 a   , circumferential ridges  702  can have a rounded cross-section, but in other embodiments can have any other known and/or convenient cross-sectional geometry. 
         [0044]      FIG. 7 b    depicts an alternate embodiment of the present device as shown in  FIG. 7 a   , in which a bushing  106  can have a longitudinal slit  202 . In some embodiments a longitudinal slit  202  can run along the entire length of a bushing  106 , but in other embodiments can run longitudinally along any known and/or convenient segment of a bushing  106 . 
         [0045]      FIG. 8 a    depicts another embodiment of the present device. As shown in  FIG. 8 a   , a bushing  106  can have a segment  802  with a plurality of longitudinal slots  804 . In some embodiments, a segment  802  can be extruded radially such that the surfaces of a bushing  106  radially adjacent to longitudinal slots  804  bulge outward. As shown in  FIG. 8 a   , a segment  802  can have a bulbous configuration, but in other embodiments can have any other known and/or convenient geometry. 
         [0046]      FIG. 8 b    depicts an alternate embodiment of the present device as shown in  FIG. 8 a   , in which a bushing  106  can have a longitudinal slit  202 . In some embodiments a longitudinal slit  202  can run along the entire length of a bushing  106 , but in other embodiments can run longitudinally along any known and/or convenient segment of a bushing  106 . 
         [0047]      FIG. 9 a    depicts another embodiment of the present device, in which a bushing  106  can have a circumferentially varying wall thickness. In such embodiments, the inner surface of a bushing  106  does not substantially align with the outer surface relative to the central longitudinal axis of a bushing  106 . An opening  902  can be non-concentric with the outer surface of a bushing  106 . 
         [0048]      FIG. 9 b    depicts an alternate embodiment of the present device as shown in  FIG. 9 , in which a bushing  106  can have a longitudinal slit  202 . In some embodiments a longitudinal slit  202  can run along the entire length of a bushing  106 , but in other embodiments can run longitudinally along any known and/or convenient segment of a bushing  106 . 
         [0049]      FIG. 10 a    depicts another embodiment of the present device, in which a bushing  106  can have a circumferentially varying wall thickness. In such embodiments, the inner surface of a bushing  106  does not substantially align with the outer surface relative to the central longitudinal axis of a bushing  106 . An opening  902  can be non-concentric with the outer surface of a bushing  106 . As shown in  FIG. 10 a   , this configuration can create a bushing  106  with a crescent-shaped cross-section. 
         [0050]      FIG. 10 b    depicts an alternate embodiment of the present device as shown in  FIG. 10 a   , in which a bushing  106  having a crescent-shaped cross section can have a longitudinal gap  1002 . In some embodiments a longitudinal gap  1002  can run along the entire length of a bushing  106 , but in other embodiments can run longitudinally along any known and/or convenient segment of a bushing  106 . A longitudinal gap  1002  can be located at the point of least thickness of the cross-section or at any other known and/or convenient location. 
         [0051]    In use, a bushing  106  can be placed into a hole on a rocker arm support  102 . A bolt  104  can be placed through a bushing  106  and then through a rocker arm support  102 . Tightening down a bolt  104  can push a bushing  106  down into the hole, filling the clearance space between a bolt  104  and a rocker arm shaft  105 . This can mitigate or eliminate the motion of a rocker arm shaft  105  against a bolt and the tapping sound that creates. In some embodiments, the present device can also dampen the sound of closing valves in the engine and decrease unwanted noise. 
         [0052]    Although the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, the invention as described and hereinafter claimed is intended to embrace all such alternatives, modifications and variations that fall within the spirit and broad scope of the claims.