Abstract:
A blower housing for use with an engine. The blower housing is adapted to receive a stream of intake air, and the engine includes at least one cylinder. The blower housing includes an intake opening, an air filter housed within a filter compartment, and an air flow duct adjacent to the filter compartment. The air flow duct is configured to direct air to the at least one cylinder. The air flow duct includes a first surface and a second surface, the first surface being angled with respect to the second surface to deflect the air passing through the duct away from the first surface toward the second surface. The first surface separates the air into a first portion and a second portion having deflected particulate matter therein. The duct also has an aperture that allows air to flow from the duct to the air filter, and an exhaust window.

Description:
RELATED APPLICATIONS 
   This application claims priority to U.S. Provisional Patent Application No. 60/649,155, filed Feb. 2, 2005, the entire contents of which is incorporated by reference herein. 

   FIELD OF THE INVENTION 
   The invention relates to internal combustion engines, and more particularly to a blower housing for an internal combustion engine. 
   BACKGROUND OF THE INVENTION 
   Many internal combustion engines are provided with fans or blowers that force cooling air over certain engine surfaces during engine operation. Air-cooled engines typically include engine cylinders and cylinder heads that incorporate heat sinks in the form of cooling fins. In this regard, fans and blowers are often provided to force air over the cooling fins, thereby cooling the engine. To further enhance the circulation of cooling air, and to thereby improve the engine cooling process, many engines include special housings and/or ductwork that guide the cooling air to different areas of the engine that require cooling. 
   The fans also can provide air to the engine for use in the combustion reaction in the cylinders. Air is drawn through a filter to remove debris from the air stream before the air enters the combustion chamber. For engines operating in environments having significant amounts of airborne dust and particulate debris, screens and the like are often provided in an attempt to reduce the amount of dirt and debris that enters the housings and ductwork. However, even with a screen in place, dirt and debris still enter the blower housing. It is desirable to further reduce the amount of dirt and debris in the air that is drawn through the filter to extend the life of the filter. 
   SUMMARY OF THE INVENTION 
   The present invention provides a blower housing for use with an engine. The blower housing is adapted to receive intake air, and includes an intake opening through which air flows into the blower housing, an air filter housed within a filter compartment, and an air flow duct adjacent to the filter compartment. The air flow duct is configured to direct air that will be used by at least one cylinder of the engine for combustion. The air flow duct has a first surface and a second surface. The first surface is angled with respect to the second surface to deflect the air passing through the duct away from the first surface toward the second surface. The first surface separates the air into a first portion and a second portion having deflected particulate matter therein. The air flow duct further includes an aperture that allows air to flow from the air flow duct to the air filter, the first portion of the air traveling through the aperture to the air filter. The duct also defines an exhaust window, the second portion of the air exiting the blower housing through the exhaust window. 
   In one embodiment, the blower housing further comprises a sidewall, and wherein the first surface and the sidewall define the aperture through which air passes to the air filter. In another embodiment, the sidewall is positioned normal to the first surface such that the first portion of the air turns sharply from a direction substantially parallel to the first surface to a direction substantially parallel to the sidewall to pass over the sidewall and into the filter. In another embodiment, the cross-sectional area of the exhaust window is sized to minimize backflow of air from the outside environment. In yet another embodiment, the duct includes an upstream end and a downstream end, and wherein the cross-sectional area of the duct is larger at the upstream end than at the downstream end. In another embodiment, the first surface includes a ramped portion that is positioned vertically above the second surface such that particulate matter in the air stream that strikes the ramped portion falls downwardly toward the second surface. 
   The invention also provides an engine having at least one cylinder, an air/fuel mixing device, a fan rotatable about an axis to draw a stream of air into the engine, and a blower housing. The blower housing includes an intake opening positioned radially outwardly from the fan, an air filter housed within a filter compartment, and at least one air flow duct. The air flow duct includes an exhaust window through which air exits the blower housing, and a first surface. The first surface has a ramped portion that deflects the air passing through the air flow duct. The ramped portion separates the air into a first portion that has a first amount of particulate matter, and a second portion having a second amount of particulate matter that is different than the first amount. 
   Other features of the invention will become apparent to those skilled in the art upon review of the following detailed description, and drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a schematic view of an internal combustion engine including a blower housing embodying the invention. 
       FIG. 2  is an exploded perspective view of the blower housing illustrated in  FIG. 1 . 
       FIG. 3  is a perspective view of the blower housing illustrated in  FIG. 1 . 
       FIG. 4  is a top view of the blower housing illustrated in  FIG. 1 . 
       FIG. 5  is a partial section view taken along line  5 - 5  of  FIG. 4 . 
       FIG. 6  is an exploded partial section view taken along line  6 - 6  of  FIG. 4 : 
       FIG. 7  is a side view of the blower housing illustrated in  FIG. 6 . 
       FIG. 8  is an exploded partial section view taken along line  8 - 8  of  FIG. 4 . 
   

   Before one embodiment of the invention is explained in detail, 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 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,” “having,” and “comprising” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. 
   DETAILED DESCRIPTION 
   The figures illustrate an internal combustion engine  10  and blower housing  14  embodying the present invention. The engine  10 , as illustrated schematically in  FIG. 1 , includes an engine block  18  that rotatably supports a crankshaft (not shown) and first and second engine cylinder assemblies  22   a ,  22   b  that each include an engine cylinder and engine cylinder head, as is known in the art. The cylinder head may be integrally formed with the cylinder, or the cylinder head and cylinder may be separate components. The cylinder assemblies  22   a ,  22   b  extend from the engine block  18  at an angle with respect to one another. In this regard the illustrated engine  10  is a V-twin engine, however the blower housing  14  can be adapted for use with other types of engines having other cylinder configurations including, without limitation, single-cylinder engines and multi-cylinder engines of inline, opposed, radial and V configurations, for example. In addition, the blower housing  14  can be utilized with engines having horizontal or vertical crankshafts, or with engines that can be operated in a variety of operating orientations. 
   The engine  10  also includes a fan  26  that is supported for rotation about an axis  30 . In some embodiments, the fan  26  is coupled to an end of the crankshaft that extends from the engine block  18 , however other fan configurations are possible as well. The fan  26  is rotatable about the axis  30  to enhance the flow of air over various engine surfaces to cool the engine  10 , as is known in the art, and to provide combustion air to the engine  10 . 
   The blower housing  14  is coupled to the engine  10  and includes a first housing portion  34  that substantially overlies a portion of the engine block  18  and defines an intake opening  38 . The intake opening  38  is in fluid communication with the fan  26  and, in the illustrated embodiment, the intake opening  38  generally surrounds the fan  26  and is substantially concentric with the axis  30 . A fan screen  40  is coupled to the fan  26  to reduce the entry of air-borne dirt and debris into the blower housing  14 . It is understood that in some embodiments, the fan screen  40  is a stationary screen that is coupled directly to the blower housing  14  and may not rotate with the fan  26 . 
   The first housing portion  34  includes a front wall  42  that is substantially normal to the axis  30 , spaced from the engine block  18 , and defines the intake opening  38 . The first housing portion  34  also includes sidewalls  46  that extend away from the front wall  42  toward the engine block  18 . In some embodiments, the sidewalls  46  are coupled directly to the engine block  18 . In other embodiments, additional walls, bosses, extensions and the like can be provided to couple the first housing portion  34  to the engine. The sidewalls  46  include both arcuate and planar sections, and extend generally parallel to the axis  30 . Of course the specific configuration of the sidewalls  46  depends at least in part upon the configuration of the engine  10  to which the blower housing  14  is coupled. The front wall  42  and the sidewalls  46  cooperate with the engine block  18  to at least partially define an air flow chamber through which cooling air can flow. 
   The engine  10  also includes an air/fuel mixing device that, in the illustrated embodiment, is a carburetor  54 . The carburetor  54  is positioned between the engine cylinder assemblies  22   a ,  22   b  and supplies a mixture of fuel and air to the engine  10  by way of an intake manifold  58  as is known in the art. The fuel used by the engine  10  can be gasoline, diesel, or other types of fuel. The intake manifold  58 , illustrated in  FIG. 2 , includes runners  62   a ,  62   b  that deliver the fuel/air mixture to the cylinder heads of the first and second cylinder assemblies  22   a ,  22   b , respectively. 
   It should be appreciated that the engine  10  may be configured for use with other air/fuel mixing devices as well. For example a fuel injection system (not shown) including among other things a throttle body, a fuel rail, and one or more injectors can be provided to inject fuel into the throttle body, intake runners  62   a ,  62   b , or directly into the engine combustion chamber. In other constructions, a gaseous fuel mixer (not shown) may be provided such that the engine can operate on fuels in gaseous form, such as natural gas. 
   Though the fan screen  40  functions to prevent some dirt and debris from entering the blower housing  14 , air drawn into the blower housing  14  through the screen  40  by the fan  26  still contains dirt and debris. Thus, it is desirable for the engine  10  to include an air filter  70  to remove this dirt and debris from the combustion air moving through the blower housing  14 . The first housing portion  34  also defines a filter compartment  74  into which the air filter  70  is placed. The blower housing  14  also includes a filter cover  78  that is coupled to the first housing portion  34  to enclose the filter compartment  74 . 
   Air flow ducts  82  run along either side of the filter compartment  74 . The air flow ducts  82  illustrated in  FIGS. 3-8  are rectangular in cross section and direct a portion of the air drawn in by the fan  26  through the air filter  70 , and a portion of the air into the environment outside the engine  10 . It should be understood that while in the illustrated embodiment the blower housing  14  includes two air ducts, in other engine configurations, especially those utilizing only one cylinder, a single air duct may be used and still fall within the scope of the present invention. In other embodiments, more than two air ducts may be used. It should be further understood that while the air flow ducts of the illustrated embodiment are rectangular in cross section, other embodiments of the present invention may include air ducts of different cross sectional shapes, including, but not limited to, round, oval, square or trapezoidal. 
   The ducts  82  include an upper or first surface  86  having a ramped portion  88 , a lower or second surface  90 , and define an exhaust window  92 . The ramped portion  88  is ramped downwardly or toward the lower or second surface  90  to deflect particles of dirt and debris in the air stream moving through the duct  82  toward the opposite second surface  90 . The ducts  82  also include a sidewall  94  downstream from the upper surface  86  and adjacent the filter compartment  74 . The upper or first surface  86  of the ducts  82  defines an opening  96  through which the air passes as it moves into the filter compartment  74 . It should be understood that in other embodiments of the present invention, the ramped portion may be provided on another surface within the duct, such as on the sidewall or on the lower surface. 
   With reference to  FIG. 7 , the ramped portion  88  is angled toward the opposite second surface  90  at an angle of approximately fifteen degrees from the surface  86 , and has a length that is approximately eleven percent of the length of the entire duct  82 . The ramped portion  88  has a width approximately equal to the width of the duct  82 . It should be understood that these dimensions are approximate, and that other dimensions are possible and still fall within the scope of the present invention. 
   When the fan  26  rotates, air is drawn through the intake opening  38  and into the first housing portion  34 . The front wall  42  and the sidewalls  46  then guide some of the air toward the cylinder assemblies  22   a ,  22   b . Depending upon the engine configuration, the front wall  42  and sidewalls  46  can be configured to guide different amounts of cooling air across the engine cylinder and cylinder head. For example, if the engine is an overhead valve or overhead cam engine, the sidewalls  46  can be configured to guide a larger percentage of the cooling air toward the outside of the cylinder head, whereas if the engine is an L-head engine, the sidewalls  46  can be configured to guide a larger percentage of the cooling air toward the outside of the engine cylinder. Various types of internal baffles and/or additional passageways can be provided to distribute the cooling air according to the cooling requirements of a specific engine. 
   Another portion of the air drawn into the blower housing  14  passes through the ducts  82 . Some of this portion of the air will pass through the intake manifold  58  into the cylinders, and some will pass through the ducts  82  and into the environment outside the engine  10 . Air running along the first surface  86  will strike the ramped portion  88 . The ramped portion  88  will deflect larger pieces of the dirt and debris in the air stream to fall to the opposite second surface  90  of the ducts  82 . The air running along the second surface  90 , including the deflected dirt and debris (i.e., the “dirty” air), will pass through the ducts  82  and out the exhaust windows  92  into the atmosphere outside the engine  10 . 
   The air running near the first surface  86  will be drawn through the opening  96  over the sidewall  94  and through the air filter  70 , where most of the remaining particles of dirt and debris that were not deflected by the ramped portion  88  will be removed. The combustion air must make a sharp turn in the ducts  82  to travel over the sidewall  94  and through the opening  96  to the filter  70 . The debris particles near the second surface  90  must overcome its momentum, as well as the force of gravity (in a vertical shaft engine configuration) and other forces from the air acting on the particles to be carried into the air filter compartment  74 . By maximizing the area of the opening  96 , the velocity of the air moving from the ducts  82  to the filter compartment  74  is kept as low as possible to reduce the amount of debris particles that can overcome the opposite forces acting on them to enter the filter compartment  74 . This further reduces the amount of debris that travels to the filter  70 . 
   The cleaned air then travels through an intake elbow  98 , through the carburetor  54 , and into the intake manifold  58 . By deflecting larger particles of dirt and debris from the air stream that travels through the filter  70 , the life of the filter may be extended as the filter is less likely to be clogged by large particles of debris. When the filter  70  needs to be cleaned and/or replaced, the filter cover  78  can be removed from the first housing portion  34  so that the user can remove the filter  70 . 
   The size of the ducts  82  controls how much air flows out of the blower housing  14 . The area of the ducts  82  from the fan  26  to the filter  74 , and thus the size of the exhaust window  92 , is optimized to ensure that there is more airflow available to the engine  10  than the engine will use for combustion, while at the same time avoiding unnecessary bleeding off of cooling air. As the ducts  82  are sized larger, the amount of air drawn into the blower housing  14  that is available for cooling the cylinder assemblies  22   a ,  22   b  is reduced. Reducing the amount of air available for cooling too much can lead to overheating problems in the engine. Thus, it is desirable to optimize the size of the ducts  82 . 
   The volume of air drawn into the blower housing  14  by the fan  26  per revolution of the engine  10  is approximately constant. The amount of air drawn into the cylinder assemblies  22   a ,  22   b  for combustion per revolution of the engine  10  changes with volumetric efficiency, and is the greatest at the peak torque of the engine. Since the combustion air flow (i.e., air flowing through the filter  70  and into the intake manifold  58  through the carburetor  54 ) is greatest at peak torque, the net flow of air out the exhaust windows  92  is lowest at peak torque. At the peak torque, the cross-sectional area of the ducts  82  at the downstream end  100  of the ramped portion  88  must be large enough to maximize the amount of “dirty” air that will flow out of the exhaust windows  92  and that little if any air will flow backwards into the exhaust windows  92  and into the filter compartment  74 . Air flowing back into the air ducts  82  could introduce more dirt and debris into the filter  70 , which could clog the filter  70  and/or reduce the useful life of the filter  70 . When there is adequate airflow available to the engine  10  for combustion (i.e., when the area of the ducts  82  is large enough), little if any air will flow backwards into the exhaust windows  92 . 
   In the blower housing  14  of the illustrated embodiment, the ducts  82  have a cross-sectional area of about one square inch at the downstream end  100  of the ramped portion  88  so that a small amount of excess air flows out of the exhaust windows  92 . This duct sizing optimizes the size of the ducts  82  so that there is some outward air flow while allowing for appropriate cooling of the engine  10 . The cross-sectional area of the ducts  82  at the upstream end  102  of the ramped portion  88  is approximately twenty-eight percent larger than the cross-sectional area of at the downstream end  100 . It is understood that while this area ratio is shown in the illustrated embodiment, other area ratios are possible and still fall within the scope of the present invention. 
   Various features of the invention are found in the following claims.