Patent Publication Number: US-6656003-B1

Title: Anti-vibration supporting structure for an outboard engine system

Description:
FIELD OF THE INVENTION 
     The present invention relates to an anti-vibration supporting structure for an outboard engine system in which a swivel shaft is laterally swingably supported on a bracket device fixed to a hull, and an outboard engine system body is supported in an anti-vibration manner on the swivel shaft with an elastic rubber interposed therebetween. 
     BACKGROUND ART 
     In general, an outboard engine system includes an engine room in which an engine is accommodated, and a case body extending downwards from the engine room to accommodate a drive shaft driven by the engine. The engine room and the case body are supported on a hull by an anti-vibration supporting device using an elastic rubber. 
     More specifically, there is employed an anti-vibration supporting device having a structure in which outer and inner peripheral surfaces of a pair of cylindrical rigid members disposed coaxially with each other are coupled to each other by elastic rubbers, or a pair of plate-shaped rigid members disposed in an opposed relation to each other are coupled to each other by elastic rubbers, thereby constituting an anti-vibration assembly, wherein inner one of the cylindrical rigid members or one of the plate-shaped rigid members is mounted to a bolt extending in an arm-shape from each frame mounted at an upper and lower locations on a swivel shaft. There is also employed another anti-vibration supporting device having a structure in which an anti-vibration assembly is formed as a single component comprising an interior rigid member (a core metal) and elastic rubbers surrounding a periphery of the interior rigid member, wherein the interior rigid member is fixed to a bolt extending in an arm-shape from each frame mounted at an upper and lower vertical locations on a swivel shaft, and the elastic rubbers are restrained in an engine room or a recess defined in a case body. 
     However, any of the anti-vibration supporting device suffers from the following problem: The elastic rubber supported on the upper rigid member is disposed in the vicinity of an upper end of the swivel shaft, and the elastic rubber supported on the lower rigid member is disposed in the vicinity of a lower end of the swivel shaft. For this reason, in order to increase the distance between the upper and lower elastic rubbers to enhance the anti-vibration effect, it is necessary to increase the length of the swivel shaft, resulting in increases in weight and cost. 
     In addition, any of the anti-vibration supporting device also suffers from a problem that a component or a structure (a nut threadedly fitted over the bolt, or a working space for operating the nut) is required for fixing the rigid members of the anti-vibration assembly to the bolt extending from the frame and hence, the anti-vibration supporting device is correspondingly complicated and increased in size, and the cost is increased. 
     DISCLOSURE OF THE INVENTION 
     The present invention has been accomplished with such circumstances in view, and it is a first object of the present invention to ensure that the distance between the upper and lower elastic rubbers on the swivel shaft is increased without extension of the length of the swivel shaft itself of the outboard engine system, thereby enhancing the anti-vibration effect. 
     It is a second object of the present invention to provide an anti-vibration supporting structure for an outboard engine system, which is simple in structure, small-sized and inexpensive in cost. 
     To achieve the first object, according to a first aspect and feature of the present invention, there is provided an anti-vibration supporting structure for an outboard engine system in which a swivel shaft is laterally swingably supported on a bracket device fixed to a hull, and an outboard engine system body is supported in an anti-vibration manner on an upper rigid member coupled to an upper end of the swivel shaft and a lower rigid member coupled to a lower end of the swivel shaft with elastic rubbers interposed therebetween, respectively, characterized in that the lower rigid member includes a swivel shaft extension extending downwards from the lower end of the swivel shaft, and elastic rubber support portions extending laterally from the lower end of the swivel shaft extension for supporting the elastic rubbers. 
     With the above arrangement, the outboard engine system body is supported at its lower portion in the anti-vibration manner by the lower rigid member having the elastic rubber support portion provided at the lower end of the swivel shaft extension extending downwards from the lower end of the swivel shaft. Therefore, the distance between the upper and lower elastic rubbers can be increased without downward extension of the swivel shaft itself to enhance the anti-vibration effect, while avoiding an increase in extra weight and an increase in cost. In addition, the elastic rubbers are supported on the elastic rubber support portions extending laterally from the lower end of the swivel shaft extension. Therefore, the distance between the left and right elastic rubbers can be decreased without interference with the swivel shaft to avoid a reduction in anti-vibration effect. 
     An oil case  41  and an extension case  42  in embodiments correspond to an outboard engine system body of the present invention. A mounting bracket  55  in the embodiments corresponds to the bracket device of the present invention, and a mount frame  63  in the embodiments corresponds to the upper rigid member of the present invention. A center frame  64  in the embodiments corresponds to the lower rigid member of the present invention, and a core metal  64   2  in the embodiments corresponds to the elastic rubber support portion of the present invention. An upper mount rubber  74  and a lower mount rubber  80  in the embodiments correspond to the elastic rubbers of the present invention. 
     To achieve the second object, according to the present invention, there is provided an anti-vibration supporting structure for an outboard engine system in which a swivel shaft is laterally swingably supported on a bracket device fixed to a hull, and an outboard engine system body is supported in an anti-vibration manner on the swivel shaft with elastic rubbers interposed therebetween, characterized in that the elastic rubbers are integrally provided around tip ends of the rigid member extending laterally from the swivel shaft, and are restrained in elastic rubber restraining portions provided in the outboard engine system body. 
     With the above arrangement, the elastic rubbers integrally provided around the tip ends of the rigid member extending laterally from the swivel shaft are restrained in elastic rubber restraining portions provided in the outboard engine system body and hence, a component or a working space for fixing the elastic rubbers to the rigid member is not required, whereby the structure of the anti-vibration supporting device for the outboard engine system can be simplified, contributing to reductions in size and cost. 
     An extension case  42  in the embodiments corresponds to the outboard engine system body of the present invention, and a rubber accommodating portion  42   2  and a cover member  81  in the embodiments correspond to the elastic rubber restraining portion of the present invention. A center frame  64  in the embodiments corresponds to the rigid member of the present invention, and a lower mount rubber  80  in the embodiments corresponds to the elastic rubber of the present invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIGS. 1 to  10  show a first embodiment of the present invention, wherein FIG. 1 is a side view of the entire arrangement of an outboard engine system; 
     FIG. 2 is an enlarged sectional view of an essential portion shown in FIG. 1; 
     FIG. 3 is a sectional view taken along a line  3 — 3  in FIG. 2; 
     FIG. 4 is an enlarged view of the essential portion shown in FIG. 1; 
     FIG. 5 is a sectional view taken along a line  5 — 5  in FIG. 4; 
     FIG. 6 is a sectional view taken along a line  6 — 6  in FIG. 2; 
     FIG. 7 is an enlarged sectional view of an essential portion shown in FIG. 5; 
     FIG. 8 is an enlarged sectional view of the essential portion shown in FIG. 5; 
     FIG. 9 is a view taken in the direction of an arrow  9  in FIG. 8; 
     FIG. 10 is a sectional view taken along a line  10 — 10  in FIG.  8 . 
     FIGS. 11 and 12 show a second embodiment of the present invention, wherein FIG. 11 is a view similar to FIG. 8; and 
     FIG. 12 is a view taken in the direction of an arrow  12  in FIG.  11 . 
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     A first embodiment of the present invention will now be described with reference to FIGS. 1 to  10 . 
     As shown in FIGS. 1 to  3 , a two-cylinder and 4-cycle engine E mounted at an upper portion of an outboard engine system O includes an engine block  11  integrally provided with a crankcase  11   1 , a cylinder head  12  coupled to the engine block  11 , and a head cover  13  coupled to the cylinder head  12 . Two pistons  14 ,  14  slidably received in two cylinder bores  11   2 ,  11   2  defined in the engine block  11  are connected to a crankshaft  15  supported in the engine block  11  through connecting rods  16 ,  16 , respectively. 
     A power generator  17  and a recoiled stator  18  are coaxially mounted at an end of the crankshaft  15  protruding upwards from the engine block  11 . A camshaft  20  is supported in a valve operating chamber  19  defined between the cylinder head  12  and the head cover  13 , and a cam pulley  21  mounted at an upper end of the camshaft  20  and a crank pulley  22  mounted at an upper portion of the crankshaft  15  are connected to each other by a timing belt  23 . An intake valve  26  and an exhaust valve  27  for respectively opening and closing an intake port  24  and an exhaust port  25  defined in the cylinder head  12  are connected to the camshaft  20  through an intake rocker arm  28  and an exhaust rocker arm  29 , respectively. An intake silencer  30 , a choke valve  31  and a variable venturi-type carburetor  32  are disposed on a right side of the engine E and connected to the intake port  24 . 
     An axis of the crankshaft  15  is disposed vertically, and axes of the cylinder bore  11   2 ,  11   2  are disposed in a longitudinal direction of an outboard engine system O, so that a side adjacent the crankcase  11   1  faces forwards, and a side adjacent the cylinder head  12  faces rearwards. The crank phases of the two pistons  14 ,  14  are the same as each other, and the timings of ignition provided by the pistons  14 ,  14  are displaced from each other through 360°. Counterweights  15   1  are mounted on the crankshaft  15  and have a balance rate of 100% for countering the mass of reciprocal movement of the pistons  14 ,  14 . Therefore, a longitudinal primary vibration caused by the reciprocal movement of the pistons  14 ,  14  is countervailed by a rotating movement of the counterweights  15   1  of the crankshaft  15 . 
     An upper surface of an oil case  41  is coupled to a lower surface of the engine E having the above-described structure. An upper surface of an extension case  42  is coupled to a lower surface of the oil case  41 , and an upper surface of a gear case  43  is coupled to a lower surface of the extension case  42 . An outer periphery of the oil case  41  and an outer periphery of lower half of the engine E are covered with an undercover  44  coupled to an upper end of the extension case  42 , and upper half of the engine E is covered with an engine cover  45  coupled to an upper end of the undercover  44 . 
     The oil case  41  is integrally provided with an oil pan  41   1 , and a suction pipe  47  including an oil strainer  46  is accommodated within the oil pan  41   1 . An exhaust passage defining member  48  is coupled to a rear surface of the oil case  41 , and an exhaust gas expanding chamber  49  is defined in the extension case  42  with a partition wall  42   1  formed therebetween. An exhaust gas exiting from the exhaust port  25  is supplied through an exhaust passage  11   3  defined in the engine block  11  into the exhaust gas passage defining member  48 ; then passed through the exhaust gas expanding chamber  49  in the extension case  42 , the inside of the gear case  43  and a hollow portion around a propeller shaft  53  which will be described hereinafter, and then discharged into the outside water. 
     A drive shaft  50  connected to a lower end of the crankshaft  15  extends through the oil case  41  and downwards within a drive shaft chamber  51  defined in the extension case  42 , and is connected through a forward/backward movement switchover mechanism  54  to a front end of the propeller shaft  53 , which is supported longitudinally in the gear case  43  and has a propeller  52  at its rear end. 
     As can be seen from FIGS. 4 and 5, a mounting bracket  55  for detachably mounting the outboard engine system O to a hull S includes an inversed J-shaped mounting bracket body  56 , and a setscrew  57  threadedly fitted in the mounting bracket body  56 . A swinging arm  59  is pivotally supported at its front end on the mounting bracket body  56  through a pivot pin  58 , and a swivel case  60  having a cylindrical portion extending vertically is integrally coupled to a rear end of the swinging arm  59 . A large number of pinholes  56   1  are provided in the mounting bracket body  56 , so that the tilting angle of the outboard engine system O about the pivot pin  58  can be regulated by inserting a pin  61  through a pinhole defined in a locking plate  60   1  fixed to the swivel case  60  and through any of the pinholes  56   1  in the mounting bracket body  56 . 
     The outboard engine system O includes upper mounts  65 ,  65  and a lower mount  66  respectively at upper and lower ends of a swivel shaft  62  relatively rotatably fitted in the swivel case  60 . Thus, the outboard engine system O is supported in an anti-vibration manner on the hull S by the upper mounts  65 ,  65  and the lower mount  66 . 
     More specifically, a rigid mount frame  63  is mounted at an upper end of the swivel shaft  62  to extend laterally from the center of the swivel shaft  62 , and upper mount rubbers  74 ,  74 , each of which is an elastomer, are mounted at left and right ends of the mount frame  63 , respectively. A rigid center frame  64  is mounted at a lower end of the swivel shaft  62  to extend laterally from the center of the swivel shaft  62 , and lower mount rubbers  80 ,  80 , each of which is an elastomer, are mounted at left and right ends of the center frame  64 . The oil case  41  serving as an engine support block and the extension case  42  fastened to the oil case  41  restrain the upper mount rubber  74 ,  74  and the lower mount rubbers  80 ,  80 , whereby the outboard engine system O is supported on the hull S in the anti-vibration manner. 
     The structure of each of the upper mounts  65 ,  65  will be described below with reference to FIGS. 5 to  7 . 
     The oil case  41  includes a pair of left and right protrusions  41   2 ,  41   2  overhanging forwards and upwards. The protrusions  41   2 ,  41   2  are formed with rubber-accommodating portions  71 ,  71  with their lower surfaces opened, respectively. On the other hand, substantially rectangular parallelepipedic upper mount rubbers  74 ,  74  are mounted at left and right ends of the mount frame  63  to cover peripheries of core metals  73 ,  73  fixed by bots  72 ,  72 , respectively. The upper mount rubbers  74 ,  74  are fitted into the rubber accommodating portions  71 ,  71  of the oil case  41  from the below. Restraining cover members  83 ,  83  are fixed to openings in the lower surface of the rubber accommodating portions  71 ,  71  by bolts (not shown), so that the upper mount rubbers  74 ,  74  are prevented from falling out of the rubber accommodating portions  71 ,  71 . 
     The structure of the lower mount  66  will be described below with reference to FIGS. 8 to  10 . 
     The center frame  64  coupled to the lower end of the swivel shaft  62  protruding downwards from the swivel case  60  is integrally provided with a swivel shaft extension  64   1  spline-fitted into and fixed to the swivel shaft  62  by two bolts  79 ,  79 , and a pair of core metals  64   2 ,  64   2  protruding laterally from a lower end of the swivel shaft extension  64   1  having a reduced lateral width. The lower mount rubbers  80 ,  80  are fixed by baking to cover outer peripheries of the core metals  64   2 ,  64   2 . A pair of left and right rubber accommodating portions  42   2 ,  42   2  are formed at a rear surface of a lower end of the extension case  42 , and a pair of left and right cover members  81 ,  81  are fastened to the extension case  42  by bolts  82 ,  82 , respectively to restrain the lower mount rubbers  80 ,  80  fitted into the rubber accommodating portions  42   2 ,  42   2  from the rear. Thus, the lower end of the extension case  42  is resiliently supported at the lower end of the swivel shaft  62  through the lower mount  66  provided with the lower mount rubbers  80 ,  80 . 
     In this manner, the lower mount rubbers  80 ,  80  are fixed by baking to cover outer peripheries of tip ends of the center frame  64 , which extends downwards from the lower end of the swivel shaft  62  and diverges laterally. Therefore, parts such as bolts and nuts for fixing the lower mount rubbers  80 ,  80  to the center frame  64  are not required, and moreover, a working space for operating such bolts and nuts is not required, whereby the structure of the lower mount  66  is simplified, which contributes to reductions in size and cost of the outboard engine system O. 
     In addition, the vertically long center frame  64  is coupled to the lower end of the swivel shaft  62 , and the lower mount rubbers  80 ,  80  are mounted at the lower end of the center frame  64 . Therefore, the lower mount rubbers  80 ,  80  can be disposed at low locations without special extension of the swivel shaft  62  itself. Thus, the distance between the upper mount rubbers  74 ,  74  and the lower mount rubbers  80 ,  80  can be increased to enhance the anti-vibration effect, while avoiding an increase in extra weight and an increase in cost. Moreover, the lower end of the swivel shaft extension  64   1  of the center frame  64  is formed at a decreased width, and the pair of core metals  64   2 ,  64   2  are mounted to protrude laterally from the portion of the decreased width. Therefore, the distance between the left and right lower mount rubbers  80 ,  80  supported on the core metals  64   2 ,  64   2  can be decreased without interference with the swivel shaft to avoid a reduction in anti-vibration effect. 
     A second embodiment of the present invention will now be described with reference to FIGS. 11 and 12. 
     The second embodiment includes a pair of left and right lower mounts  66 ,  66  at the lower portion of the extension case  42 . Each of the lower mounts  66  includes a rubber accommodating portion  42   2  provided in a recessed manner in a side of the extension case  42 . A lower mount rubber  80  fitted in the rubber accommodating portion  42   2  is restrained by a cover member  81  fixed to the extension case  42  by two bolts  82 ,  82 . A pipe-shaped core metal  85  is fixed by baking to the center of the lower mount rubber  80 , and passed loosely through an opening defined between mating surfaces of the rubber accommodating portion  42   2  and the cover member  81  to protrude forwards. 
     On the other hand, the center frame  64  coupled to the lower end of the swivel shaft  62  by two bolts  79 ,  79  includes a swivel shaft extension  64   1  extending downwards from the lower end of the swivel shaft  62 , and a pair of supporting arms  64   3 ,  64   3  protruding laterally from a lower end of the swivel shaft extension  64   1 . The extension case  42  is supported on the center frame  64  with the lower mount rubbers  80 ,  80  interposed therebetween by tightening, by nuts  87 ,  87 , bolts  86 ,  86  passed from the front to the rear through the left and right supporting arms  64   3 ,  64   3  and the core metals  85 ,  85  of the left and right lower mount rubbers  80 ,  80 . 
     Even in the second embodiment, the lower end of the center frame  64  coupled to the lower end of the swivel shaft  62  is connected to the lower mount rubbers  80 ,  80  through the core metals  85 ,  85  and hence, the lower mount rubbers  80 ,  80  can be disposed at low locations without special extension of the swivel shaft  62  itself, and the distance between the upper mount rubbers  74 ,  74  and the lower mount rubbers  80 ,  80  can be increased to enhance the anti-vibration effect, while avoiding an increase in extra weight and an increase in cost. In addition, the left and right supporting arms  64   3 ,  64   3  are provided to protrude from the lower end of the swivel shaft extension  64   1  of the center frame  64  and hence, the distance between the left and right lower mount rubbers  80 ,  80  can be decreased without interference with the swivel shaft  62  to avoid a reduction in anti-vibration effect. 
     Although the embodiments of the present invention have been described in detail, it will be understood that the present invention is not limited to the above-described embodiments, and various modifications in design may be made without departing from the subject matter of the invention. 
     For example, in the first embodiment, the lower mount rubbers  80 ,  80  are baked and fixed directly to the core metals  64   2 ,  64   2  protruding laterally from the swivel shaft extension  64   1 . In the second embodiment, the core metals  85 ,  85  integral with the lower mount rubbers  80 ,  80  are fixed by the bolts  86 ,  86  and the nuts  87 ,  87  to the supporting arms  64   3 ,  64   3  protruding laterally from the swivel shaft extension  64   1 . Namely, the center frame  64  may be connected directly or indirectly to the lower mount rubbers  80 ,  80 . 
     A mode in which the left and right supporting arms  64   3 ,  64   3  of the center frame  64  are connected indirectly to the lower mount rubbers  80 ,  80 , includes a mode in which outer and inner peripheral surfaces of a pair of cylindrical rigid members disposed coaxially are coupled to each other by an elastic rubber, and the inner cylindrical rigid member is fixed to the supporting arms  64   3 ,  64   3  by bolts, or a mode in which a pair of plate-shaped rigid members disposed in an opposed relation to each other are coupled to each other by an elastic rubber, and one of the plate-shaped rigid members is fixed to the supporting arms  64   3 ,  64   3  by bolts. 
     In addition, in the embodiments, the present invention is applied to the lower mount  66 , but in claim 2, the present invention is also applicable to an upper mount. 
     INDUSTRIAL APPLICABILITY 
     As discussed above, the anti-vibration supporting structure for the outboard engine system according to the present invention can be applied to an outboard engine in which an outboard engine system body is supported on a swivel shaft laterally swingably supported on a bracket device with an elastic rubber interposed therebetween.