Abstract:
A rocker box assembly for a motorcycle engine having a cylinder head. The rocker box assembly includes a base, a cover, and a breather assembly. The base is configured to be coupled to the cylinder head. The cover is coupled to the base and cooperates with the base to it least partially define a rocker chamber and to at least partially define a breather assembly housing within the rocker chamber. The breather assembly is positioned within the breather assembly housing and is operable to vent a pressure pulse from within the engine.

Description:
BACKGROUND 
       [0001]    The present invention relates to breather assemblies for internal combustion engines. 
         [0002]    During operation of a piston-cylinder type internal combustion engine, reciprocal movement of the pistons in the cylinders creates pressure pulses within the various chambers of the engine. For example, during an intake or expansion stroke of the piston, pressure within the crankcase of the engine generally increases, whereas during a compression or exhaust stroke of the piston, pressure within the crankcase of the engine generally decreases. The pressure pulses in the crankcase can be communicated to other chambers within the engine, such as the rocker box area, via breather passages, oil flow passageways, and the like. To reduce internal engine losses, often referred to as “pumping losses,” many internal combustion engines utilize a breather system that operates to dissipate the pressure pulses within the crankcase, the rocker box, and other chambers of the engine. 
         [0003]    Movement of various internal engine components also creates an oil mist that is carried throughout the engine by the pressure pulses. It is often desirable to separate as much of the oil mist as possible from the gasses that may be expelled from the engine through the breather system. Many breather systems remove the oil mist from the air by routing the internal engine gasses through screens, meshes, and various serpentine paths before discharging the gasses to the atmosphere. To reduce emissions to the atmosphere, some breather systems route some or all of the gasses expelled from the breather system to the engine&#39;s air/fuel intake stream (e.g. to the airbox or to the intake manifold). 
       SUMMARY 
       [0004]    In one embodiment of the invention, a rocker box assembly includes a base, a cover, and a breather assembly. The base is configured to be coupled to the cylinder head. The cover is coupled to the base and cooperates with the base to at least partially define a rocker chamber and to at least partially define a breather assembly housing within the rocker chamber. The breather assembly is positioned within the breather assembly housing and is operable to vent a pressure pulse from within the engine. 
         [0005]    In another embodiment, the cover of the rocker box assembly includes an aperture The breather assembly is positioned within the rocker chamber and is operable to vent a pressure pulse from within the engine through the breather assembly and out the aperture of the cover. 
         [0006]    In yet another embodiment, a breather assembly includes a body having a baffle portion defining a serpentine path and a check valve member coupled to the body. The body is integrally formed as a single piece and is configured to be disposed within the rocker chamber. 
         [0007]    Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is a side view of a motorcycle that includes rocker box assemblies embodying the present invention. 
           [0009]      FIG. 2  is a perspective view of a cylinder head and a rocker box assembly of the motorcycle of  FIG. 1 . 
           [0010]      FIG. 3  is a partially exploded view of the rocker box assembly of  FIG. 2  with the cover of the rocker box assembly removed. 
           [0011]      FIG. 4  is a top view of the cylinder head and rocker box assembly of  FIG. 2  with the cover of the rocker box assembly removed. 
           [0012]      FIG. 5  is a cross-section view of the rocker box assembly taken along line  5 - 5  of  FIG. 4 , but with the cover of the rocker box assembly coupled to the base. 
           [0013]      FIG. 6  is a bottom view of the base of the rocker box assembly of  FIG. 2 . 
           [0014]      FIG. 7  is a bottom view of the base of the rocker box assembly of  FIG. 2  including a gasket 
           [0015]      FIG. 8  is a bottom view of the cover of the rocker box assembly of  FIG. 2 . 
           [0016]      FIG. 9  is a side view of a breather assembly of the rocker box assembly of  FIG. 2 . 
           [0017]      FIG. 10  is a cross-section view of the rocker box assembly taken along line  10 - 10  of  FIG. 2 . 
       
    
    
       [0018]    Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of 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. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. Further, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings. 
       DETAILED DESCRIPTION 
       [0019]      FIG. 1  illustrates a motorcycle  12  that includes a frame  14  and an engine assembly  16  coupled to the frame  14 . The motorcycle  12  further includes wheels  18  that support the motorcycle  12  on a riding surface  20 . The engine assembly  16  includes a crankcase  22 , a first cylinder assembly  24  that extends upwardly and forwardly from the crankcase  22 , and a second cylinder assembly  26  that extends upwardly and rearwardly from the crankcase  22 . The first and second cylinder assemblies  24  and  26  are arranged with respect to one another define a “V-twin” engine configuration. In the illustrated “V-twin” engine configuration the cylinder assemblies  24  and  26  are orientated at a 45 degree angle with respect to each at a 22.5 degree angle with respect to an axis  28  that is normal to the riding surface  20 . 
         [0020]    Each of the cylinder assemblies  24  and  26  includes an engine cylinder  30 ,  32  and a cylinder head  34 ,  36  coupled to an end of a respective cylinder  30 ,  32 . Each cylinder assembly  24 ,  26 , also includes a rocker box assembly  40 ,  42 , respectively, coupled to a respective cylinder head  34 ,  36 . In the illustrated construction, both of the rocker box assemblies  40  and  42  are substantially the same. Therefore, only the rocker box assembly  40  and its operation will be discussed in detail below. 
         [0021]    Referring to  FIGS. 2 and 3 , the rocker box assembly  40  includes a cover  46 , a base  48 , and a breather assembly  50 . The cover  46  is coupled to the base  48  such that the cover  46  and the base  48  define a rocker chamber  52  ( FIG. 5 ). 
         [0022]    As illustrated in  FIGS. 3 and 4 , the base  48  includes a lower wall  54  and a perimeter wall  56  that extends upwardly from the lower wall  54 . The lower wall  54  defines a pair of valve openings  58   a ,  58   b  through which engine valves (not shown) extend. The lower wall  54  of the base  50  also defines a central opening  60  and a pushrod opening  62  through which pushrods extend. A central plane  64  of the base  48  is defined as a plane that extends through the center of the central opening  60 , generally through the center of the pushrod opening  62 , between the valve openings  58   a ,  58   b , and generally normal to the lower wall  54 . 
         [0023]    The base  48  further includes four rocker supports  70   a - 70   d  that extend upwardly from the lower wall  54 . Each rocker support  70   a - 70   d  defines a rocker support bore  74 . The rocker support bores  74  of one pair of rocker supports  70   a ,  70   b  are substantially aligned and define a first axis  76  on one side of the central plane  64 . Rocker support bores  74  of the other pair of rocker supports  70   c ,  70   d  are also substantially aligned and define a second axis  78  on an opposite side of the central plane  64 . The rocker support bores  74  of the rocker supports  70   a ,  70   b  support a first rocker shaft (not illustrated) that is generally co-axial with the first axis  76 , and the rocker support bores  74  of the rocker supports  70   c ,  70   d  support a second rocker shaft (not illustrated) that is generally co-axial with the second axis  78 . Rockers (not illustrated) pivot on the rocker shafts during engine operation. 
         [0024]    Each of the rocker supports  70   a - 70   d  also defines a cover mounting aperture  80  and a base mounting aperture  82 . The base mounting apertures  82  are substantially normal to and extend through the lower wall  54  of the base  48 . The base mounting apertures  82  are aligned with corresponding apertures in the cylinder head  34  and a fastener is inserted into each of the mounting apertures  82  to couple the base  48  to the cylinder head  34 . The base  48  further defines additional mounting apertures  84  that extend through the base  48  and are designed to receive fasteners to couple the base  48  to the cylinder head  34 . 
         [0025]    The perimeter wall  56  of the base  48  defines an outer seal recess  86  that extends around the perimeter of the base  48  in the top of the perimeter wall  56 . The base  48  further defines an inner seal recess  88  that surrounds the central opening  60 . The recesses  86 ,  88  receive seals  92 ,  94 , respectively, to substantially seal an interface between the base  48  and the cover  46 . 
         [0026]    Referring to  FIGS. 3 ,  4 , and  5 , the base  48  further defines a breather assembly receiving aperture  98 , a breather assembly inlet chamber  100 , and breather assembly inlet passages  102 . The breather assembly receiving aperture  98  includes a ledge  106  that supports the breather assembly  50  within the receiving aperture  98 . As best seen in  FIG. 4 , the central plane  64  of the base  48  extends generally through the center of the breather assembly receiving aperture  98 . While the illustrated breather assembly receiving aperture  98  is generally cylindrical, in other constructions the breather assembly receiving aperture can take other suitable shapes. 
         [0027]    The illustrated breather assembly inlet passages  102  are generally cylindrical apertures that are substantially normal to the lower wall  54  of the base  48 . The breather assembly inlet passages  102  provide fluid communication between the rocker chamber  52  and the breather assembly inlet chamber  100 . While the illustrated base  48  includes two breather assembly inlet passages  102 , one on each side of the central plane  64 , in other constructions the base can include any suitable number of breather assembly inlet passages at any suitable location. 
         [0028]    As best seen in  FIGS. 5 and 6 , grooves  108   a  and  108   b  in the base  48  and a gasket  110  located between the base  48  and the cylinder head  34  ( FIG. 3 ) cooperate to define drainage passageways  112   a ,  112   b . The drainage passageways  112   a ,  112   b  provide fluid communication between the breather assembly inlet chamber  100  and the valve openings  58   a ,  58   b  ( FIG. 4 ), respectively. The gasket  110  inhibits fluid communication between the valve openings  58   a ,  58   b  and the breather assembly inlet chamber  100  except through the drainage passageways  112   a ,  112   b.    
         [0029]    Referring to  FIGS. 2 ,  5 , and  8 , the cover  46  includes a top wall  120  and a perimeter wall or side walls  124  that extend from the top wall  120 . The cover  46  defines a central plane  125  that is centrally located between two of the side walls  124  and normal to the top wall  120 . The central plane  125  of the cover  46  is generally co-planar with the central plane  64  of the base  48  when the base  48  and cover  46  are assembled. 
         [0030]    Referring to  FIGS. 5 and 8 , the side walls  124  of the cover  46  include substantially planar ends  126  that directly engage to the outer seal member  92  and the perimeter wall  56  of the base  48  to substantially seal the interface between the cover  46  and the base  48  around the perimeter of the rocker chamber  52 . 
         [0031]    Referring to  FIGS. 2 and 8 , the cover  46  further includes cover apertures  130  that can be aligned with the cover mounting apertures  80  of the base  48  ( FIG. 4 ) such that the apertures  80  and  130  receive fasteners  132  to couple the cover  46  to the base  48 . 
         [0032]    Referring to  FIGS. 5 and 8 , the cover  46  defines a breather assembly outlet chamber  136  and a breather assembly outlet aperture  140  that extends through the top wall  120  of the cover  46 , in fluid communication with the breather assembly outlet chamber  136 . The breather assembly outlet aperture  140  and the breather assembly outlet chamber  136  are centrally located on the central plane  125  of the cover  46 . 
         [0033]    As best seen in  FIG. 5 , together the breather assembly outlet chamber  136 , defined by the cover  46 , and the breather assembly receiving aperture  98 , defined by the base  48 , define a breather assembly housing  144 . The breather assembly housing  144  is located within the rocker chamber  52  and houses the breather assembly  50 . 
         [0034]    The breather assembly outlet chamber  136  and the breather assembly receiving aperture  98 , which together define the breather assembly housing  144 , are integrally formed with the cover  46  and the base  48 , respectively, as a single piece. In one construction, the base  48  is cast and the breather assembly receiving aperture  98  is integrally cast with the base  48  such that the base  48  and the breather assembly receiving aperture  98  are a single piece. Similarly, the cover  46  is also cast and the breather assembly outlet chamber  136  is integrally cast with the cover  46  such that the cover  46  and the breather assembly outlet chamber  136  are a single piece. In other constructions, the breather assembly receiving aperture  98  and the breather assembly outlet chamber  136  can be integrally formed with the base  48  and cover  46 , respectively, using any suitable method, such as molding, machining, and the like. 
         [0035]    Referring to  FIGS. 2 and 5 , the breather assembly outlet aperture  140  receives a coupling  148  that defines a passageway  150 . The coupling  148  can be used to couple a conduit such as tubing, piping and the like, to the rocker box assembly  40 . The conduit can provide fluid communication between the rocker box assembly  40  and another portion of the motorcycle  12 , such as the throttle body, air intake, etc. 
         [0036]    Referring to  FIGS. 5 and 8 , the cover  46  further includes breather assembly inlet passage covers  156  that extend from the inside surface of the top wall  120 . The illustrated cover  46  includes two inlet passage covers  156  that correspond with the two breather assembly inlet passages  102  of the base  48 . As best seen in  FIG. 5 , the inlet passage covers  156  receive the inlet passages  102 . The inner dimension of the inlet passage covers  156  are slightly larger than the outer dimension of the inlet passages  102 . Therefore, a serpentine flow path is created by the inlet passage covers  156 , the purpose of which will be discussed below. 
         [0037]    Referring to  FIGS. 3 and 9 , the illustrated breather assembly  50  includes a body portion  160 , a check valve member  162 , and filter media  164 . The body portion  160  defines a longitudinal axis  166  and includes a central aperture  168  through which the longitudinal axis  166  extends and a plurality of vent apertures  170  that surround the central aperture  168 . The body portion  160  includes a baffle portion  174  having a plurality of fins  176 . The illustrated fins  176  are orientated at an angle θ with respect to the longitudinal axis  166 . In the illustrated construction, the angle θ is approximately 30 degrees. In other constructions, the angle θ can range from about 25 degrees to about 35 degrees, and in yet other constructions, the angle θ is greater than about 22.5 degrees. 
         [0038]    The body portion  160  of the breather assembly  50  further includes a seal receiving groove  182  that receives the seal  184 , which is an O-ring seal in the illustrated construction. As best seen in  FIG. 5 , the seal  184  substantially seals the breather assembly housing  144  at the interface of the cover  46  and the base  48 . 
         [0039]    In the illustrated construction, the body portion  160  of the breather assembly  50  is integrally formed as a single piece, such as by casting, molding, machining and the like. 
         [0040]    Referring to  FIGS. 3 and 5 , the check valve member  162  of the breather assembly  50  includes a resilient valve member  190  and a protrusion  192  that extends from the resilient valve member  190 . When the check valve member  162  is coupled to the body portion  160 , the resilient valve member  190  covers the vent apertures  170  and the protrusion  192  extends through the central aperture  168  of the body portion  160  to couple the check valve member  162  to the body portion  160 . 
         [0041]    The filter media  164  can be any suitable filter media. In the illustrated construction, the filter media is open-cell foam and is located between the baffle portion  174  and the check valve member  162 . 
         [0042]    Referring to  FIGS. 3 and 5 , to assemble the breather assembly  50  with the base  48  and the cover  46 , the breather assembly  50  is placed or set within the breather assembly receiving aperture  98  of the base  48 . The breather assembly  50  is supported within the breather assembly receiving aperture  98  by the ledge  106 . Because the ledge  106  defines a generally circular aperture and the portion of the breather assembly  50  supported by the ledge  106  is also generally circular, the breather assembly  50  can be placed within the breather assembly receiving aperture  98  at any rotational position about the longitudinal axis  166  of the breather assembly  50 . 
         [0043]    With the cover  46  of the rocker box assembly  40  removed from the base  48 , the breather assembly  50  is free to move with respect to the base  48 . Therefore, the breather assembly  50  can be removed from the breather assembly receiving aperture  98  by grasping the breather assembly  50  and lifting it from the receiving aperture  98 . In the illustrated construction, the breather assembly  50  is not fixed with respect to the base  48  until the cover  46  is coupled to the base  48  and thus a portion of the breather assembly  50  is directly between the cover  46  and the base  48  to substantially prevent the breather assembly  50  from moving with respect to the cover  46  and the base  48 . Therefore, the breather assembly  50  is not directly fastened to the base  48  and the breather assembly  50  is freely coupled to the base  48 , and the breather assembly  50  can easily be removed and installed when the cover  46  has been removed from the base  48 . 
         [0044]    Referring to  FIGS. 1 ,  4 , and  5 , during operation of the engine  16 , pressure pulses are created within the engine  16  by moving components, such as pistons. Also, air/oil mist, vapor, mixture, etc. is circulated through the engine  16  by the pressure pluses and the air/oil mist enters the rocker box chamber  52  through passages such the pushrod opening  62 , which is in fluid communication with the cylinder head  34 . The air/oil mist enters the rocker box chamber  52  and migrates across the rocker box  40  toward the breather assembly inlet passages  102 . Because the illustrated rocker box  40  includes a breather assembly inlet passage  102  on each side of the central plane  64 , the air/oil mist is drawn from both sides of the rocker chamber  52  and only a single breather assembly  50  is utilized in the illustrated construction. The flow of the air/oil mist is generally represented by the arrows  200  in  FIG. 5 . 
         [0045]    Before entering the breather assembly inlet passages  102 , the air/oil mist travels through the serpentine flow path created by the breather assembly inlet passage covers  156 . The serpentine flow path created by the inlet passage covers  156  causes at least some of the oil particles in the air/oil mist to accumulate on the inlet passage covers  156 . The oil that accumulates on the inlet passage covers  156  eventually drips or flows onto the lower wall  54  of the base  48 . 
         [0046]    Referring to  FIGS. 5 and 9 , after traveling through the serpentine flow path created by the inlet passage covers  156 , the air/oil mist enters the breather assembly inlet passages  102  and flows into the breather assembly inlet chamber  100 . As indicated by the arrows  200 , in the breather assembly inlet chamber  100 , the air/oil mist turns upward and travels through the baffle portion  174  of the breather assembly  50 . As the air/oil mist travels across the fins  176  of the baffle portion  174  at least some of the oil in the air/oil mist collects on the fins  176  and eventually drips or flows down onto the gasket  110 . 
         [0047]    Referring to  FIGS. 1 and 10 , because the illustrated engine  16  is a “V-twin” engine, the rocker boxes  40  and  42  are at a 22.5 degree angle, labeled β, with respect to the riding surface represented by the line  20 ′ in  FIG. 10 . Therefore, the longitudinal axis  166  of the breather assembly  50  is at a 22.5 degree angle, labeled α, with respect a plane  28 ′ that is parallel to the plane  28 . Thus, in the illustrated construction, the fins  176 , which are at the fin angle θ of 30 degrees with respect to the longitudinal axis  166  are at an angle of at least 7.5 degrees with respect to the riding surface  20 ,  20 ′ (30 degrees minus 22.5 degrees). 
         [0048]    In the illustrated construction, because the fin angle θ is greater than 22.5 degrees, the fins  176  are downwardly tapered with respect to the riding surface  20  regardless of the orientation of the breather assembly  50  within with breather assembly receiving aperture  98  and the oil that collects on the fins  176  flows down along the fins  176  due to gravity and eventually drips or flows onto the gasket  110 . Therefore, oil is substantially prevented from collecting or pooling on the fins  176 . 
         [0049]    With the gasket  110  at the angle β (22.5 degrees in the illustrated construction) with respect to the riding surface  20 ,  20 ′, gravity causes the oil to flow on the gasket  110  and through the drainage passage  112   b  and through the valve opening  58   b  back to the cylinder head. The oil can flow through either the drainage passages  112   a ,  112   b  depending on which drainage passage  112   a ,  112   b  is at a lower elevation with respect to the riding surface  20 ,  20 ,′. 
         [0050]    The illustrated base  48  includes the two grooves  108   a  and  108   b  that define the two drainage passages  112   a ,  112   b  so that the same base  48 , and therefore the same rocker box assembly, can be used with either the front cylinder head  34  or the rear cylinder head  36 . Therefore, depending on whether the base  48  is used with the front or rear cylinder head  34 ,  36 , one of the drainage passages  112   a ,  112   b  will be at the lowest elevation of the breather assembly inlet chamber  100  with respect to the riding surface  20 ,  20 ′. 
         [0051]    Referring to  FIG. 5 , after the air/oil mist travels through the baffle portion  174  of the breather assembly  50 , the air/oil mist travels through the filter media  164 . The filter media  164  collects additional oil. Oil collected by the filter media  164  eventually travels down along the fins  176  as discussed above. 
         [0052]    Referring to  FIGS. 3 and 5 , as a result of pistons and other moving components within the engine, pressure pulses are created within the rocker chamber  52 . When the pressure of the air increases past a predetermined point, the air deflects the resilient valve member  190  and the air/oil mist, after traveling through the filter media  164 , travels though the vent apertures  170  and into the breather assembly outlet chamber  136 . The mist then exits the breather assembly outlet chamber  136  through the breather assembly outlet aperture  140  in the cover  46 . The mist then passes through the passage  150  of the coupling  148  and through a conduit (not illustrated) to another portion of the motorcycle  12  such as the air cleaner or throttle body where the mist is introduced into the air/fuel intake flow path of the engine  16 . 
         [0053]    The pressure pulses can also cause the pressure in the rocker chamber  52  to be less than the pressure in the breather assembly outlet chamber  136 . In such a condition, the resilient valve member  190  of the check valve member  162  seals tightly against the body portion  160  of the breather assembly  50 , sealing the vent apertures  170  to substantially prevent flow from the breather assembly outlet chamber  136  into the breather assembly inlet chamber  100 . 
         [0054]    Various features and advantages of the invention are set forth in the following claims.