Abstract:
An air cleaner for small internal combustion engines, including a removable or replaceable air cleaner element detachably mounted within an air cleaner cavity which is defined at least on part by the shroud of the engine. The air cleaner element includes engagement structure for releasable engagement with a wall of the air cleaner cavity to permit mounting of the sir cleaner element within the cavity, and removal of the air cleaner element from the cavity, without the use of tools. In addition, a cover is provided for releasably engaging the air cleaner cavity to cover the air cleaner element.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   This application claims the benefit under Title 35, U.S.C. § 119(e) of U.S. Provisional Patent Application Ser. No. 60/402,841, entitled INTERNAL COMBUSTION ENGINE, filed on Aug. 12, 2002. 

   BACKGROUND OF THE, INVENTION 
   1. Field of the Invention 
   The present invention relates to small internal combustion engines of the type used with lawnmowers, lawn tractors, other small working implements, or sport vehicles, for example. In particular, the present invention relates to an air cleaner assembly for such engines. 
   2. Description of the Related Art 
   Intake systems of small internal combustion engines provide an air/fuel mixture for combustion with the combustion chamber(s) of the engines to drive the engines. Typically, such intake systems include either a carburetor or a fuel injector for mixing air with fuel to provide the air/fuel mixture. Further, the intake system includes an air cleaner assembly for separating particulate matter such as dust, dirt, or other debris from the intake air before the intake air is drawn into the carburetor for mixing with fuel. 
   Typically, the air cleaner assembly includes an air cleaner housing in the form of a separate component attached to the engine or blower housing of the engine by suitable brackets, fasteners, etc. The air cleaner housing contains a filter element made of a fibrous material, or screen made of a mesh material, which permits the intake air to pass therethrough, yet which traps particulate matter which could be harmful to the engine if same were allowed to pass with the intake air into the carburetor. 
   One problem with known air cleaner assemblies is that the air cleaner housing is usually not positioned on the engine in a manner in which it is easily accessible for maintenance, such as changing the filter element when same becomes clogged with particulate matter. For example, the air cleaner housing may be located on a portion of the engine which is difficult for a user to access. Further, when the air cleaner housing is attached to the engine using brackets, fasteners, etc., failure of the attachment assembly may result during the operational life of the engine. 
   Also, known air cleaner housings usually include a cover which is difficult to remove for access to the air filter element. Often, the cover is attached to the air cleaner housing with a plurality of fasteners, such that tools are required to remove the cover from the air cleaner housing. 
   Further, if the cover of known air cleaner housings is too easily removable, same may become detached from the air cleaner body during operation of the engine. In this manner, the filter element may become dislodged from, or even fall out of, the air cleaner housing during running of the engine, reducing or eliminating the filtering of particulate matter from the intake air drawn into the carburetor and the engine. 
   Finally, the air cleaner housing is typically a bulky component which takes up a large amount of space around the engine, which space is at a premium in small internal combustion engines. 
   What is needed is an air cleaner assembly for a small internal combustion engines which is an improvement over the foregoing. 
   SUMMARY OF THE INVENTION 
   The present invention provides an air cleaner system for small internal combustion engines, including a removable or replaceable air cleaner element detachably mounted within an air cleaner cavity which is defined at least in part by the shroud of the engine. The air cleaner element includes engagement structure for releasable engagement with a wall of the air cleaner cavity to permit mounting of the air cleaner element within the cavity, and removal of the air cleaner element from the cavity, without the use of tools. In addition, a cover is provided for releasably engaging the air cleaner cavity to cover the air cleaner element. 
   In one embodiment, an engine is provided including a shroud which covers at least a portion of the engine crankcase and engine cylinder(s), as well as the flywheel of the engine. The shroud includes an upper front portion having a recessed portion which at least partially defines therein the air cleaner cavity. The recessed portion is in communication with the intake end of the engine carburetor. A cover is removably attached to the shroud to define the air cleaner cavity therebetween. The air cleaner cavity includes a plurality of mounts for releasable receipt of a corresponding plurality of tabs on the air cleaner element to releasably attach the air cleaner element to the base wall of the air cleaner cavity and to position the air cleaner element centrally within the air cleaner cavity about the intake end of the carburetor. 
   Advantageously, the present arrangement allows for installation of the air cleaner element within the air cleaner cavity, and removal of the air cleaner element from the air cleaner cavity for cleaning and/or replacement, without the use of tools. Additionally, because the air cleaner element is fixedly attached within the air cleaner cavity, the air cleaner element remains in position to filter dirt, dust, or other debris from the intake air even if the cover should fall off or be removed from the shroud. 
   Further, because the air cleaner cavity is defined with a recessed portion of the shroud, the present air cleaner assembly does not include an air cleaner housing which is separate from the shroud, thereby eliminating the need for brackets, fasteners, etc., which would otherwise be needed to attach a separate air cleaner housing to the engine. The air cleaner cavity is positioned within an easily accessible area of the engine, and is integrated in to the engine shroud to minimize the space around the engine which is occupied by the air cleaner assembly. 
   In one form thereof, the present invention provides an internal combustion engine, including an engine housing; a shroud covering at least a portion of the engine housing; a cover mounted to the shroud, the shroud and the cover cooperating to define a substantially enclosed air cleaner cavity; and an air cleaner element releasably mounted within the air cleaner cavity. 
   In another form thereof, the present invention provides an internal combustion engine, including an engine housing; a shroud covering at least a portion of the engine housing; a cover mounted to the shroud, the shroud and the cover cooperating to define a substantially enclosed air cleaner cavity; and an air cleaner element disposed within the air cleaner cavity; and means for releasably retaining the air cleaner element within the air cleaner cavity. 
   In a further form thereof, the present invention provides an internal combustion engine, including an engine housing; a carburetor attached to the engine housing; a shroud covering at least a portion of the engine housing, the shroud defining a recessed cavity therein in communication with the carburetor; a plurality of mounts within the recessed cavity; an air cleaner element disposed within the recessed cavity, the air cleaner element releasably retained by the mounts. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention itself will be better understood by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawings, wherein: 
       FIG. 1  is front perspective view of a horizontal crankshaft, V-twin engine including an air cleaner assembly in accordance with the present invention; 
       FIG. 2  is a fragmentary view of a portion of the engine of  FIG. 1 , showing the cover of the air cleaner assembly exploded away therefrom, the air cleaner element visible within the air cleaner cavity; 
       FIG. 3A  is a fragmentary view of a portion of the engine of  FIG. 1 , showing the cover and air cleaner element exploded away from the air filter cavity to show the interior of the air filter cavity; 
       FIG. 3B  is a perspective view of the air cleaner element of  FIG. 3A ; 
       FIG. 4  is a fragmentary view showing interlocking portions of the air cleaner element and the shroud in a non-engaging position; and 
       FIG. 5  is a fragmentary view showing interlocking portions of the air cleaner element and the shroud in an engaged position to releasably retain the air cleaner element within the air cleaner cavity. 
   

   Corresponding reference characters indicate corresponding parts throughout the several views. The exemplification set out herein illustrates one preferred embodiment of the invention, in one form, and such exemplification is not to be construed as limiting the scope of the invention any manner. 
   DETAILED DESCRIPTION 
   Referring first to  FIG. 1 , a small internal combustion engine  20  is shown as a horizontal crankshaft V-twin engine, such as that described in detail in U.S. patent application Ser. No. 10/409,262, entitled INTERNAL COMBUSTION ENGINE, filed on Apr. 8, 2003 assigned to the assignee of the present invention, the disclosure of which is expressly incorporated herein by reference. Although engine  20  is shown as a horizontal crankshaft V-twin engine, the present invention may be embodied within any small internal combustion engine, such as vertical crankshaft V-twin engines, or horizontal or vertical crankshaft single cylinder engines. 
   Engine  20  generally includes crankcase  22  having a pair of engine cylinders (not visible) mounted to crankcase  22  in the manner described in the above-incorporated U.S. patent application Ser. No. 10/409,262. A horizontally disposed crankshaft  24  is rotatably carried within crankcase  22 , and is coupled to a pair of conventional piston/connecting rod assemblies (not shown), one corresponding to each engine cylinder. 
   Engine cover or shroud  26  is connected to crankcase  22  and covers at least a portion of each of crankcase  22  and the cylinders. Shroud  26  may be formed of metal, or from an injection-molded or vacuum-formed plastic material, for example. Cylinder wraps  28 , typically made of a relatively thin sheet metal, are also connected to crankcase  22  and the cylinders, and closely surround the cylinders for directing cooling air around the cylinders. Fuel tank  30  is mounted via brackets  32  to the upper ends of cylinder wraps  28 . Air inlet screen  34  is mounted to shroud  26 , and covers an opening in shroud  26  through which intake air is drawn by rotation of the engine flywheel (not shown), which is attached to an end of crankshaft  24  which extends externally of crankcase  22 . Specifically, rotation of the flywheel draws intake air through louvers  36  in screen  34  and into an area defined between crankcase  22  and shroud  26 . Additional details regarding engine  20 , and in particular, the control system of engine  20 , are discussed in detail in U.S. patent application Ser. No. 10/409,202, entitled ENGINE CONTROL SYSTEM, filed on April 8, 2003 assigned to the assignee of the present invention, the disclosure of which is expressly incorporated herein by reference. 
   Referring to  FIGS. 2 and 3A , an upper or distal portion  38  of shroud  26 , which is generally spaced upwardly or away from crankshaft  24  and faces the front side of engine  20 , includes a recessed portion  40  integrally formed therewith. Recessed portion  40  of shroud generally includes side wall  42  and base wall  44  having a circular opening  46  therein. Air inlet openings  48  may be formed in side wall  42  to allow air to pass from the area between crankcase  22  and shroud  26  into the interior of recessed portion  40  of shroud  26 . Base wall  44  may alternatively be formed as a separate component from the remainder of shroud  26 , with base wall  44  and side wall  42  positioned in an abutting or close-fitting engagement with one another to define recessed portion  40 . 
   Carburetor  50  is mounted to the rear surface of base wall  44  of shroud  26 , and includes an intake passage or throat  52  extending therethrough. Carburetor  50  mixes fuel with air which is drawn into throat  52  to provide an air/fuel mixture for combustion within engine  20 . Choke valve  54  and a throttle valve (not shown) are rotatably disposed within throat  52  to regulate the mass air/fuel intake of engine  20 . In this manner, carburetor  50  and recessed portion  40  of shroud  26  are in fluid communication with one another through opening  46  in shroud  26 . 
   Shroud  26  includes a plurality of slots  56  spaced therearound, which are shown disposed within side wall  42 . Shroud  26  also includes a plurality of mounts  58  which are spaced around the periphery of base wall  44 . Mounts  58 , discussed in detail below, may be integrally formed with base wall  44  or with side wall  42 , for example, or may be formed as separate components attached either to base wall  44  or to side wall  42 . 
   Cover  60  may be made of a suitable flexible plastic material, for example, and includes outer surface  62  and an inner surface opposite outer surface  62 , as well as a plurality of lugs  66  depending from cover  60  which releasably engage within slots  56  of shroud  26  via a releasable, snap-fit engagement to secure cover  60  to shroud  26 . Cover  60  may be released from shroud  26 , for example, by grasping the edges of cover  60  and flexing cover  60  to dislodge lugs  66  from slots  56 , followed by removing cover  60  from shroud  26 . Cover  60  covers recessed portion  40  defined within shroud  26  such that cover  60  and shroud  26  cooperate to define a substantially enclosed air cleaner cavity  70  therebetween, with air cleaner cavity  70  in communication with intake air by suitable means, and also in communication with the inlet end of carburetor  50 . In this manner, air cleaner cavity  70  is defined by shroud  26  and cover  60 , such that air cleaner cavity  70  is integrated into shroud  26  and does not comprise a separate component which must be attached via brackets, fasteners, etc., to the housing of engine  20 , as in known air cleaner assemblies. 
   Air cleaner element  72  is shown in  FIGS. 3A and 3B  as a substantially annular air filter member; however, the shape and overall profile of air cleaner element  72  may vary. Air cleaner element  72  generally includes top plate  74 , bottom plate  76 , and filter media  78  captured between top plate  74  and bottom plate  76 . Top plate  74  and bottom plate  76  may be formed of molded rubber or plastic, for example, and may be molded or otherwise formed about filter media  78  such that filter media  78  is integrally bonded to, and captured between, top plate  74  and bottom plate  76 . Filter media  78  may be made of an air-permeable paper, which is folded in an accordion-like fashion to increase its exposed surface area. Alternatively, filter media  78  may be formed of an air-permeable foam, a sponge-like material, or a screen/mesh material. 
   Bottom plate  76  includes central opening  80 , shown in  FIG. 3B , around which filter media  78  is radially disposed. As discussed below, central opening  80  of bottom plate  76  may be aligned with opening  46  of base wall  44  of shroud  26 . Bottom plate  76  additionally includes a plurality of tabs  82  spaced therearound, which project from the outer circumference of bottom plate  76 . Tabs  82  may be integrally formed with bottom plate  76 , or may be separately attached to bottom plate  76 . As shown in  FIGS. 4 and 5 , each tab  82  includes a tapered or rounded nose portion  84 , ramp surface  86 , and rear edge  88 . Ramp surface  86  is generally inclined from nose portion  84  to rear edge  88 . 
   Mounts  58  are integrally formed in base wall  44  of shroud  26 , and include resilient fingers  90  extending parallel to base wall  44 , with fingers  90  terminating in lugs  92 . 
   To mount air cleaner element  72  within air cleaner cavity  70 , air cleaner element  72  is positioned within the interior of air cleaner cavity  70 , with bottom plate  76  of air cleaner element  72  in abutment with base wall  44 , such that central opening  80  of bottom plate  76  is aligned concentrically about opening  46  in base wall  44 , with the interior of air filter element  72  in communication with throat  52  of carburetor  50 . In this position, tabs  82  of air cleaner element  72  are positioned between respective mounts  58  of base wall  44 . Thereafter, air cleaner element  72  is rotated within air cleaner cavity  70  in a first direction indicated by the arrow in  FIG. 2 , from the position shown in  FIG. 4  to the position shown in  FIG. 5 , such that tabs  82  and mounts  58  engage one another. Specifically, as shown in  FIGS. 4 and 5 , nose portions  84  of tabs  82  move beneath fingers  90  of mounts  58 , and ramp surfaces  86  of tabs  82  gradually engage lugs  92  of fingers  90  to flex fingers  90  outwardly away from base wall  44 . Eventually, as tabs  82  continue to pass beneath fingers  90 , lugs  92  of fingers  90  will clear rear edges  88  of tabs  82 , allowing fingers  90  to flex inwardly toward base wall  44  such that lugs  92  engage behind rear edges  88  of tabs  82  to thereby releasably retain air cleaner element  72  in position. Thereafter, cover  60  is attached to shroud  26  in the manner described above to substantially enclose air cleaner cavity  70 . 
   The engagement between tabs  82  and mounts  58 , described above, engages bottom plate  76  with base wall  44  to thereby form a seal between bottom plate  76  of air cleaner element  72  and base wall  44  of shroud  26 , such that dirt, dust, or other particulate matter is prevented from passing between bottom plate  76  of air cleaner element  72  and base wall  44  of shroud  26  and into throat  52  of carburetor  50 . Alternatively, air cleaner element  72  may include mounts  58  and shroud  26  may include tabs  82 . Further, other modes for releasable attachment of air cleaner element  72  within air cleaner cavity  70  may become apparent to one of ordinary skill in the art in view of the teachings herein. 
   During operation of engine  20 , ambient air is drawn through louvers  36  of air inlet screen  34  into the space between crankcase  22  and shroud  26  by rotation of the flywheel. A portion of this air is drawn through air inlet openings  48  in side wall  42  and into air cleaner cavity  70 . Alternatively, intake air may enter air cleaner cavity  70  by another manner. For example, cover  60  may include one or more air intake openings (not shown) through which intake air may be drawn into air cleaner cavity  70  directly from the atmosphere. Alternatively, base wall  44  may include one or more of air inlet openings  48  through which intake air may enter air cleaner cavity  70 . 
   Air within air cleaner cavity  70  then passes through filter media  78  of air cleaner element  72 , through opening  46  in base wall  44 , and into the intake end of carburetor  50 . Filter media  78  captures any dirt, dust, or other particulate matter from the air and prevents same from entering carburetor  50 . 
   Through use, filter media  78  may become clogged by particulate matter and may need to be removed from air cleaner cavity  70  for cleaning or replacement. To remove air cleaner element  72 , cover  60  is detached from air cleaner cavity  70  to expose air cleaner cavity  70  and air cleaner element  72  therewithin. Thereafter, air cleaner element  72  may be grasped by a user, and then rotated along a second direction opposite to the above-described first direction indicated by the arrow in  FIG. 2 , to detach air cleaner element  72  from base wall  44  of shroud  26  in the opposite manner as described above with respect to attachment of air cleaner element  72 . Specifically, when air cleaner element  72  is rotated from the position shown in  FIG. 5  to the position shown in  FIG. 4 , rear edges  88  of tabs  82  engage lugs  92  of fingers  90  to bias same upwardly such that tabs  82  may be rotated out of engagement with fingers  90  and mounts  58 . Thereafter, air cleaner element  72  may be removed from air cleaner cavity  70  for cleaning or replacement. A new air cleaner element  72  may be installed within air cleaner cavity  70  in the manner described above. 
   Advantageously, the releasable engagement between tabs  82  of air cleaner element  72  with mounts  58  of shroud  26  retain air cleaner element  72  in position such that bottom plate  76  of air cleaner element  72  is sealed against base wall  44  of shroud  26  to prevent dust, dirt, or other particulate matter from passing therebetween and entering into carburetor  50 . Also, even through air cleaner element  72  experiences vibrations during running of engine  20 , the releasable engagement between tabs  82  of air cleaner element  72  with mounts  58  of shroud  26  retain air cleaner element  72  in position. Additionally, even if cover  60  should become detached from shroud  26  during operation of engine  20 , air cleaner element  72  is retained within air cleaner cavity  70  and is operable to remove dirt, dust, or other particulate matter from the intake air which passes into carburetor  50 . 
   While this invention has been described as having a preferred design, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.