Patent Publication Number: US-7217166-B2

Title: Cowling structure for outboard motor

Description:
RELATED APPLICATIONS 
   This application is based on and claims priority to Japanese Patent Application No. 2004-378531, filed Dec. 28, 2004, the entire contents of which is hereby expressly incorporated by reference. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present application generally relates to outboard motors, and more particularly to outboard motors with a cowling structure including a top cowl and a bottom cowl. 
   2. Description of the Related Art 
   Watercraft vehicles, such as boats, are often powered by an outboard motor having an internal combustion engine. Outboard motors can be used to propel watercraft. Outboard motors often have an engine disposed within a protective cowling. Protective cowlings typically include a top cowl and a bottom cowl. The top cowl is often releasably coupled to the bottom cowl so that the top cowl can be removed to expose the engine. 
   Japanese Patent Publication No. 60-60098, Japanese Patent Publication No. 02-32196, and Japanese Patent Publication No. 08-268384 disclose outboard motors that have top and bottom cowls coupled together by engaging bottom cowl hooks attached to an opening edge of the bottom cowl and top cowl hooks attached to an opening edge of the top cowl. These types of top cowls are often made of reinforced resin and thus are relatively heavy and non-recyclable. A bolt is often embedded in the top cowl and couples the top cowl hook to the top cowl. The bolt is typically embedded in a thickened portion of the top cowl, which is often formed by a die-cutting process. Unfortunately, the weight of the top cowl is undesirably increased due to this thickened portion. 
   Other outboard motor cowlings have top cowl hooks that are riveted to the top cowls. Unfortunately, the heads of the rivets are often on the outside of the top cowls and exposed to the external environment. These visible portions of the rivets may be unsightly and reduce the overall aesthetics of the outboard motor. 
   SUMMARY OF THE INVENTION 
   In some aspects of the present invention, an outboard motor comprises a cowling configured to enclose an engine therewithin. The cowling comprises a top cowl and a bottom cowl. The top cowl comprises a top cowl opening edge and a top cowl coupling assembly. The top cowl coupling assembly comprises a top cowl hook and a hook mounting member that is bonded to an inner side of the top cowl. The hook mounting member comprises a nonferrous metal and has a generally uniform thickness, the bottom cowl comprises a bottom cowl opening edge and a bottom cowl coupling assembly coupled to an inner side of the bottom cowl. The top cowl hook is configured to engage the bottom cowl coupling assembly so as to releasably couple the top cowl to the bottom cowl. 
   In other aspects of the present invention, a cowling for an outboard motor is provided. The cowling comprises a top cowl having an opening edge. A hook mounting plate is bonded to an inner surface of the top cowl near the opening edge. The hook mounting plate comprises a nonferrous metal and a central portion protruding from the inner surface of the top cowl. A top cowl hook is coupled to the central portion. A bottom cowl is configured to mate with the top cowl so as to enclose an engine therewithin. The bottom cowl has a bottom cowl hook coupled to an opening edge of the bottom cowl. The top cowl hook is configured to releasably engage the bottom cowl hook. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above-mentioned and other features of the invention disclosed herein are described below with reference to the drawings of a preferred embodiment. The illustrated embodiment is intended to illustrate, but not to limit the invention. The drawings contain the following figures. 
       FIG. 1  is a side elevational view of an outboard motor configured in accordance with a preferred embodiment of the present invention. An associated watercraft, on which the outboard motor is mounted, is partially shown in section. Several of the internal components of the outboard motor are illustrated in phantom. 
       FIG. 2  is a top plan view of a bottom cowl that houses an engine. The engine is illustrated in phantom. 
       FIG. 3  is a cutaway side view of a top cowl. 
       FIG. 4  is a bottom elevational view of the top cowl of  FIG. 3 . 
       FIG. 5  is a top plan view of a bottom cowl coupling assembly of the bottom cowl. 
       FIG. 6  is a cross-sectional view of the bottom cowl coupling assembly of  FIG. 5  taken along the line VI—VI. 
       FIG. 7  is a cross-sectional view of the bottom cowl coupling assembly of  FIG. 5  taken along the line VII—VII. 
       FIG. 8  is a plan view of a top cowl hook coupled to the top cowl as viewed from the interior of the top cowl. 
       FIG. 9  is a cross-sectional view of the top cowl hook of  FIG. 8  taken along the line IX—IX. 
       FIG. 10  illustrates the top cowl hook coupled to the bottom cowl coupling assembly of the bottom cowl. 
       FIG. 11  is a cross-sectional view of a seal formed between the top cowl and bottom cowl. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   With reference to  FIG. 1 , a watercraft has an outboard motor  1  that is configured in accordance with certain features, aspects, and advantages of the present invention. The outboard motor  1  is a typical marine drive, and thus all the embodiments below are described in the context of an outboard motor. The embodiments, however, can be applied to other multi-piece cowlings, as will become apparent to those of ordinary skill in the art. 
   The illustrated watercraft of  FIG. 1  has a hull  100  that can float in the water. The hull  100  carries the outboard motor  1 , which has a propulsion unit  4  and an internal combustion engine  10  (shown in phantom). The engine  10  of the outboard motor  1  powers the propulsion unit  4  which propels the watercraft. The illustrated propulsion unit  4  is a single propeller system; however, other types of propulsion units can be used as well, such as, for example, a dual counter-rotational propeller system, a jet drive, and the like. The outboard motor  1  is supported on the transom  100   a  of the hull  100  by a clamp bracket  2  so as to place at least a portion of the propulsion unit  4  in a submerged position when the watercraft rests in the water. 
   A swivel bracket  5  is coupled to the clamping bracket  2 . The swivel bracket  5  has upper and lower damper members  3  for supporting the propulsion unit  4 . The clamp bracket  2  can be vertically rotated about the horizontal tilt shaft  6 . The outboard motor  1  is preferably steerable and/or tiltable by moving the brackets  2 ,  5 . 
   With reference to  FIGS. 1 and 2 , the illustrated outboard motor  1  includes the internal combustion engine  10  which is preferably a multi-cylinder, four-cycle engine. Engines having a different number of cylinders, other cylinder arrangements, various cylinder orientations (e.g., upright cylinder banks, and V-type), and operating on various combustion principles (e.g., four stroke, crankcase compression two-stroke, diesel, and rotary) are all practicable for use with the air intake system disclosed herein. The engine  10  comprises an engine body defining at least one cylinder bore therethrough. A cylinder head assembly is connected to the cylinder bore, and a piston is disposed within the cylinder bore. The cylinder bore, the cylinder head assembly, and the piston cooperate to define a variable combustion chamber. 
   The propulsion unit  4  has a housing formed by a cowling  7 , an upper case  8 , and a lower case  9 . The upper case  8  is attached to the bottom of an exhaust guide  11 . The engine  10 , preferably a four-stroke engine, is supported by the exhaust guide  11  and surrounded by the cowling  7 . 
   A crankshaft  12 , disposed vertically in the engine  10 , is connected to the upper end of a drive shaft  13  which extends vertically through the inner space of the upper case  8 . The lower end of the drive shaft  13  is connected to a forward-reverse shifting mechanism  14 . The forward-reverse shifting mechanism  14  is housed within the lower case  9 . A propeller shaft  15  extends horizontally from the forward-reverse shifting mechanism  14 . A propeller  16  is attached to the rear end of the propeller shaft  15  extending out of the lower case  9 . 
   As shown in  FIG. 1 , the cowling  7  includes a bottom cowl  20  and a top cowl  40 . The bottom cowl  20  and the top cowl  40  cooperate to define an engine compartment configured to accommodate the engine  10 . In some embodiments, including the illustrated embodiment, a bottom portion of the engine  10  is disposed in the bottom cowl  20 . The bottom cowl  20  preferably comprises metal, such as aluminum. The bottom cowl  20  can be formed by die-casting or other suitable manufacturing process. 
   As seen in  FIGS. 3 and 4 , the top cowl  40  includes a molding  41  positioned between the engine  10  and an intake opening  42  of the top cowl  40 . The molding  41  has a pair of right and left air intake openings  41   a . Air introduced through the intake opening  42  is drawn through the air intake openings  41   a . The air then proceeds to the engine  10 . The air can also be drawn into an air cleaner or other components of the outboard motor  1 . Water drops on the molding  41  are collected and discharged through a discharge hose  49  (see  FIG. 4 ) to limit the amount of water that reaches the engine  10 . 
   With respect to  FIGS. 1 and 2 , the bottom cowl  20  has an opening edge  20   a  defining an opening configured to accommodate the engine  10  (shown in phantom in  FIG. 2 ). A rib  20   a   1  extends outwardly from the edge  20   a , as shown in  FIGS. 7 and 11 . The bottom cowl  20  includes one or more bottom cowl coupling assemblies  21  configured to engage the top cowl  40 . The illustrated bottom cowl  20  includes three bottom cowl coupling assemblies  21 . A pair of coupling assemblies  21  are positioned at opposing sides of the bottom cowl  20 . Another coupling assembly  21  is positioned at the front of the opening edge  20 . The coupling assemblies  21  can also be at other locations. 
   With respect to  FIGS. 5 and 6 , the bottom cowl coupling assembly  21  comprises a supporting holder  22 , a bottom cowl hook  23 , and a mounting bolt  24  that couples the bottom cowl hook  23  to the supporting holder  22 . As shown in  FIGS. 5 and 7 , a spring  25  (not shown in  FIG. 6 ) extends between one side of the bottom cowl hook  23  and a stay  29 . The supporting holder  22  is secured to a mounting boss  20   b  extending inwardly from the opening edge  20   a  of the bottom cowl  20  towards the engine  10 . One or more mounting fasteners  27 , such as mounting bolts, can couple the supporting holder  22  to the mounting boss  20   b.    
   As shown in  FIG. 6 , the mounting bolt  24  couples the bottom cowl hook  23  to a supporting shaft  28  extending horizontally from the lever  26 . The supporting shaft  28  is rotatably supported by the supporting holder  22 . The lever  26  and the bottom cowl hook  23  can be rotated together about an axis  112 . The lever  26  extends vertically through the mounting boss  23   b.    
   A mounting bolt  30  couples the stay  29  to the mounting boss  20   b , as shown in  FIG. 7 . The spring  25  extends between the stay  29  and a supporting part  23   a  of the bottom cowl hook  23 . In some embodiments, the spring  25  biases the engaging part  23   b  of the bottom cowl hook  23  towards the opening edge  20   a . The illustrated spring  25  pulls the bottom cowl hook  23  about the mounting bolt  24 , as indicated by the arrow  101  in  FIG. 7 . 
   With reference again to  FIGS. 1 and 3 , the top cowl  40  preferably comprises nonferrous metal formed by a pressing process. In some embodiments, for example, the top cowl  40  is formed by pressing a nonferrous metal plate, such as aluminum and magnesium plate, as detailed below. 
   As shown in  FIG. 9 , the top cowl  40  has an opening edge  40   a  that extends inwardly. The illustrated opening edge  40   a  is bent inwardly to form a curved part  40   a   1 . The curved part  40   a   1  preferably is formed by bending the opening edge  40   a  of the top cowl  40  inwardly into a curled shape (see  FIGS. 8 and 9 ). In some embodiments, including the illustrated embodiment, the curved part  40   a   1  defines a generally U-shaped channel  130  sized to receive at least a portion of the top cowl coupling assembly  43 . The open side of the channel  130  preferably faces upwardly and extends continuously or discontinuously along the opening edge  40   a.    
   Top cowl coupling assemblies  43  are disposed on the interior of the top cowl  40  and cooperate with the bottom coupling assemblies  21  to releaseably couple the top cowl  40  to the bottom cowl  20 . One, two, three, or more coupling assemblies  43  can be positioned along the interior of the top cowl  40 . The illustrated top cowl  40  of  FIG. 4  has three coupling assemblies  43 . A pair of coupling assemblies  43  are positioned at opposing sides of the bottom cowl  20 . Another coupling assembly  43  is positioned at the front of the opening edge  20 . The coupling assemblies  43  of the top cowl  40  are preferably positioned such that they mate with the coupling assemblies  21  of the bottom cowl  20  when the top cowl  40  is placed on the bottom cowl  20 . 
   As shown in  FIGS. 8 and 9 , the coupling assembly  43  of the top cowl  40  includes a hook mounting member  44 , a top cowl hook  45 , mounting bolts  46   a ,  46   b , a nut plate  46   c , a damper holder  47 , and a positioning damper  48 . The hook mounting member  44  can comprise a nonferrous material or other suitable material. The illustrated hook mounting member  44  is formed from a nonferrous metal plate. The metal plate is formed by a pressing process. The pressed metal plate is coupled (e.g., bonded, affixed, or otherwise attached) to the inner side  120  of the opening edge  40   a  of the top cowl  40 . The illustrated hook mounting member  44  is bonded to the inner side  120  of the wall  140 . As used herein, the term “bond” is a broad term and includes, without limitation, affixing, adhering, or other suitable means for coupling together the hook mounting member  44  to the wall  140 , without having to use mechanical fasteners, such as bolts. Welding, glue, adhesive, bonding material, and the like can be used to bond the hook mounting member  44  to the wall  140 . However, in additionally embodiments mechanical fasteners can be used in combination with bonding to ensure that the hook mounting member  44  is securely coupled to the wall  140  of the top cowl  40 , if desired. 
   The wall  140  of the top cowl  40  and the hook mounting member  44  can be made of the same or similar materials. In some embodiments, the wall  140  of the top cowl  40  and the hook mounting member  44  comprise a nonferrous metal, such as aluminum, magnesium, and combinations thereof. This can reduce the weight of the top cowling  40  as compared to the top cowlings comprising, e.g., reinforced resin. Additionally, corrosion of the hook mounting member  44  and/or the top cowl  40  can be reduced. In some embodiments, at least the portions of the hook mounting member  44  and the wall  140  contacting each other can be made of the same material, preferably a nonferrous metal. 
   With reference to  FIGS. 8 and 9 , the hook mounting member  44  preferably includes a bonding part  44   a , a hook fixing part  44   b  and elongate positioning legs  44   c . The hook fixing part  44   b  is formed by drawing during the pressing process. In some embodiments, the edges of the mounting member  44  are restrained while the hook fixing part  44   b  is stretched, or drawn, into the desired shape. As such, the costs of production and the cross-length of a space defined by the hook fixing part  44   b  and the top cowl  40  can be reduced. An upper side  44   b   1  and a left and a right side  44   b   2  extend form the fixing part  44   b  to the bonding part  44   a . The hook fixing part  44   b  is open at the bottom  44   b   3 . If water enters the inner cavity of the cowling  7  of the outboard motor  1 , the closed upper side  44   b   1  can keep the water away from the mounting part. The hook fixing part  44   b  in a box shape can also enhance the strength of the hook mounting member  44 . In some embodiments, a person can manually hold the hook mounting member  44  from the underside of the hook fixing part  44   b , which helps one easily assemble the hook mounting member  44 . For example, the hook fixing part  44   b  can be spaced from the wall  140  such that a person&#39;s finger can fit between the wall  140  and the hook fixing part  44   b  during the assembly process. 
   With reference to  FIGS. 8–10 , the bonding part  44   a  has a generally flat face that can mate with the inner side  120  of the wall  140 . The bonding part  44   a  also has an upper edge side  44   a   1  that is curved, preferably having a U-shaped profile. A left side of the upper edge side  44   a   1  extends downwardly to form a vertically oriented positioning leg  44   c , and a right side of the upper edge side  44   a   1  extends downwardly to form another vertically oriented positioning leg  44   c . The positioning legs  44   c  are spaced from each other and generally straight. Each positioning leg  44   c  preferably has a distal end  44   c   1  extending downward a sufficient distance so as to engage the curved part  40   a   1 , as shown in  FIG. 9 . The curved part  40   a   1  can curve around the distal end  44   c   1 . As such, the curved part  40   a   1  retains the hook mounting member  44  to limit movement of the positioning legs  44   c  away from the wall  140  of the top cowl  40 . Such a configuration reduces or eliminates the need for a separate mounting structure for securing the positioning legs  44   c , or other portions of the hook mounting member  44 . The elongate positioning legs  44   c  help positioning during assembly because the distal ends  44   c   1  of the legs  44   c  can be inserted into the channel  130 , thereby providing easier and more accurate assembly. 
   The hook fixing part  44   b  can be interposed between the nut plate  46   c  and the top cowl hook  45 . In some embodiments, including the illustrated embodiment, the hooking fixing part  44   b  has a generally uniform thickness and protrudes from the wall  140 . The mounting bolts  46   a  extend through the top cowl hook  45 , hook fixing part  44   b , and nut plate  46   c . The top cowl coupling assembly  43  includes two mounting bolts  46   a  which securely couple the top cowl hook  45  to the hook fixing part  44   b . Other coupling arrangements can also be employed. 
   With reference to  FIGS. 8 and 10 , the damper holder  47  is coupled to the hook fixing part  44   b . In the illustrated embodiment, a mounting bolt  46   b  couples the holder  47  to the hook fixing part  44   b , although other mounting arrangements can be employed. A positioning damper  48  (shown in phantom) is mounted to the holder  47 . The positioning damper  48  can be received by the positioning recesses  22   a  of the bottom cowl coupling assembly  21  to position the bottom cowl coupling assembly  21  with respect to the top cowl coupling assembly  43 . Alternatively or additionally, the bottom cowl coupling assembly  21  can have other types of alignment structures. 
     FIG. 10  illustrates the top cowl coupling assembly  43  releasably coupled to the bottom cowl coupling assembly  21 . The engaging part  45   a  of the top cowl hook  45  is pressed against the engaging part  23   b  of the bottom cowl hook  23 . In some embodiments, including the illustrated embodiment, the engaging part  45   a  is positioned below the engaging part  23   b  of the bottom cowl hook  23 . The bottom cowl hook  23  can disengage the top cowl hooks  45  when the lever  26  is rotated in the direction indicated by the arrow  131  (see  FIG. 7 ). To couple the assembles  21 ,  43  together, the engaging part  23   b  of the bottom cowl hook  23  is rotated by the spring  25  in the opposite direction to return to the bottom cowl hook  23  to the illustrated position. 
   When the top cowl  40  and bottom cowl  20  are attached to each other, the positioning damper  48  of the top cowl coupling assembly  43  is received by the positioning recess  22   a  of the bottom cowl coupling assembly  21  so as to align the coupling assemblies  21 ,  43 . This can facilitate placement of the top cowl  40  on the bottom cowl  20 . In the illustrated embodiment of  FIG. 10 , the positioning damper  48  and corresponding recess  22   a  each have a generally frusto-conical shape; however, the damper  48  and recess  22   a  can have other shapes, if desired. 
   When the top cowl  40  and the bottom cowl  20  are coupled with each other, a seal member  50  forms a seal between the top cowl  40  and the bottom cowl  20 , as shown in  FIG. 11 . Various types of seal members can be employed. The illustrated seal member  50  preferably has an engaging part  50   a  and a seal part  50   b . The seal member  50  can be coupled to the top cowl  40  by engaging the engaging part  50   a  with the curved part  40   a   1  formed along the opening edge  40   a  of the top cowl  40 . The seal member  50  can extend between along the opening edge  40   a  between the top cowl coupling assemblies  43 . In some embodiments, a plurality of seal members  50  extend between the lower attaching arms  44   a  of adjacent hook mounting members  44 . 
   When the top cowl  40  and the bottom cowl  20  are coupled together, the seal part  50   b  preferably is pressed against the rib  20   a   1  formed along the opening edge  20   a  of the bottom cowl  20  and a flat part  20   c  inside the opening edge  20   a . A seal is formed by the curved part  40   a   1  along the opening edge  40   a  of the top cowl  40  and the opening edge  20   a  of the bottom cowl  20 . The seal member  50  can be compressible so as to form a relatively good seal with ease and reliability. Although the seal member  50  is attached to the top cowl  40 , alternative embodiments may have a seal member  50  attached to the bottom cowl  20 . The seal member  50  can comprise a compliant material, such as rubber, polymer, or other material suitable for forming a seal, such as various elastomer materials. One of ordinary skill in the art can select the type and configuration of the seal members based on the configuration of the bottom and top cowls  20 ,  40 . 
   In some embodiments, including the illustrated embodiment of  FIG. 10 , the hook mounting member  44  is coupled to the inner side of the opening edge  40   a  of the top cowl  40  to which the top cowl hook  45  is mounted. The top cowl hook  45  and the bottom cowl hook  23  are engaged with each other. The hook mounting structure  44  is thus not visible from outside of the assembled cowling  7 , thereby maintaining an improved appearance. As mentioned above, the top cowl  40  and the hook mounting member  44  can comprise the same material, e.g., nonferrous metal, such as aluminum and/or magnesium. Such an embodiment can be lightweight as compared to the cowlings made of reinforced resin. Additionally, corrosion of the hook fixing member  44   b  can be reduced as compared to cowlings made of different materials which contact each other. 
   The hook mounting member  44  has the hook fixing part  44   b  formed by a drawing process, preferably preformed in conjunction with the pressing process. This can reduce costs and the distance between the hook fixing part  44   b  and the wall  140  of the top cowl  40 . In some embodiments, the hook fixing part  44   b  is spaced from the wall  140  of the top cowl  40  such that a person&#39;s finger can be positioned between the hook fixing part  44   b  and the wall  140  of the top cowl  40 . 
   The top cowl hook  45  and the bottom cowl hook  23  can engage each other when the upper cowl  40  is positioned on the bottom cowl  20 . The bottom cowl  20  can exert a downwardly directed force on the top cowl hook  45 , which is supported by the bonding part  44   a  of the hook mounting member  44 . The upper edge side  44   a   1  of the bonding part  44   a , formed into an arc shape, allows this force to be decentralized and minimizes stress concentrations, thereby enhancing the overall bonding strength between the top cowl coupling assembly  43 . 
   Although the invention has been disclosed in the context of certain embodiments and examples, it will be understood by those skilled in the art that the invention extends beyond the specifically disclosed embodiments to other alternative embodiments and/or uses and obvious modifications and equivalents thereof. Accordingly, it is not intended that the invention be limited, except as by the appended claims.