Patent Publication Number: US-6336435-B1

Title: Outboard motor

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is related to and claims priority, under 35 U.S.C. §119, from Japanese Patent Application No. 11-150258, filed on May 28, 1999, the entire contents of which are hereby incorporated by reference herein. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an outboard motor having an engine to which a starter motor and an oil filter are mounted. 
     2. Discussion of Background 
     In general, an engine of an outboard motor is mounted such that a crankshaft is directed vertically uprightly, and the engine comprises a crankcase directed forward (towards a hull in a mounted state of the outboard motor), a cylinder block disposed to a rear portion of the crankcase and a cylinder head disposed to a rear portion of the cylinder block. When the engine is of a four-stroke-cycle in-line multi-cylinder type, an intake system is disposed on one side of the engine, and an exhaust system, an electrical equipment box, an oil filter and the like are disposed on the other side of the engine as shown in Japanese Patent Laid-open Publication No. HEI 10-176541. A starter motor for starting the engine is disposed in a central portion of a front surface of the crankcase. By disposing each of these parts in accordance with such a layout, a space in a small engine cover of the outboard motor can be utilized effectively, and the balance of weight between the left and right sides of the outboard motor can be achieved. 
     Further, for fixing the starter motor, there is a fixing structure as shown in FIGS. 9 and 10 in which fixing pieces  102  and  103  projecting from a peripheral surface of a starter motor  101  are fastened to starter fixing bosses  105  and  106  integrally extending from a crankcase  104  from the front side by fixing bolts  107 , and an exclusive mounting bracket is omitted to reduce the number of parts. In this arrangement, the axial direction of each fixing bolt  107  is horizontal direction. 
     However, according to the above structure, since the oil filter is disposed on a side surface of the engine, when the outboard motor is mounted to a hull and it is difficult to touch the oil filter with a hand and also difficult to exchange the oil filter, and maintenance performance of the engine is poor. On the other hand, electric equipments and the like are disposed below the starter motor in many cases, but since this position is located below the engine, it is not preferable in terms of waterproofing. Further, since the starter motor largely projects to the central portion of the front surface of the crankcase, forward and backward length of the engine is increased. 
     On the other hand, if the starter motor  101  is fixed to the crankcase  104  as shown in FIGS. 9 and 10, since the axial direction of the fixing bolt  107  does not coincide with the axial direction of a crank bearing  108  formed on the crankcase  104 , the crank bearing  108  and a screw hole of the fixing bolt  107  must be formed separately. As a result, the relative positional precision of the starter motor  101  with respect to the crankshaft will be ensured, and there is an adverse possibility that engagement backlash between a pinion gear of the starter motor  101  and a ring gear of a flywheel which is mounted at an upper end of the crankshaft after the engine is assembled becomes improper. 
     The crankcase  104  is formed at its outer surface with a large number of parts such as fastening bosses for fastening and fixing the crankcase  104  itself to the cylinder block and also formed with part fixing bosses for disposing other parts. Therefore, it is difficult to freely set and design upper and lower positions of the starter fixing bosses  105  and  106 . Further, in the case of the fixing structure shown in FIG. 9, if the heights of the left and right starter fixing bosses  105  and  106  are slightly inaccurate, torsion or bending stress is applied to the fixing pieces  102 ,  103  of the starter motor  101 , and service life of the fixing pieces  102 ,  103  may therefore be shortened. On the other hand, in the case of the fixing structure shown in FIG. 10, since a working direction of the screw hole of the fixing bolt  107  is quite different from those of many other holes, working cost will be increased. 
     As described above, since there are many constraints for mounting the starter motor, in order to dispose the starter motor at a desired position, it is necessary to form the fixing pieces of the starter motor into complicated shapes. However, this results in increase in cost for producing the starter motor, and results in reduction in general utilization. In addition, when the starter motor is mounted to the crankcase, it is necessary to hold the heavy starter motor with one hand and to fasten the fixing bolt with the other hand at the same time, thus the operability of the outboard motor being made poor. 
     SUMMARY OF THE INVENTION 
     The outboard motor of the present invention has been invented to solve the above problems, and it is a first object of the invention to provide an outboard motor including an improved arrangement of a starter motor and an oil filter for effectively utilizing a space, for easily exchanging the oil filter from a hull side and for enhancing the maintenance performance of an engine. 
     Another object of the present invention is to provide an outboard motor capable of shortening a forward and backward length of the engine to make the outboard motor compact. 
     A further object of the present invention is to provide an outboard motor capable of enhancing the relative positional precision of the starter motor with respect to a crankshaft, enhancing the flexibility of mounting position of the starter motor and enhancing the mounting operation of the starter motor. 
     A still further object of the present invention is to provide an outboard motor having an improved outer appearance and providing an improved fixing structure for the starter motor and others. 
     These and other objects can be achieved according to the present invention buy providing an outboard motor comprising: 
     an engine disposed of a vertical type including a crankcase in which a crankshaft extends vertically perpendicularly, a cylinder block disposed rear side of the crankcase, and a cylinder head disposed rear side of the cylinder block in a usable mounted state of the outboard motor; 
     a starter motor mounted to a front surface portion of the crankcase; and 
     an oil filter mounted to the crankcase at a portion below the starter motor. 
     In preferred embodiments, the starter motor and said oil filter are disposed so as to be deviated sideways in locations with respect to an axis of the crankshaft as viewed in a front view. 
     The crankcase is provided at an upper portion thereof with a starter fixing boss projecting horizontally and the starter motor is fastened to the starter fixing boss by means of fixing bolt which is directed in a perpendicular direction. The starter motor is provided with a fixing flange which spreads in a horizontal direction and the fixing flange is mounted on the starter fixing boss by means of the fixing bolt. 
     The crankcase is provided with a starter holding boss located below the starter fixing boss, a holding band is fixed to the starter holding boss, and a lower portion of the starter motor is held between the holding band and the starter holding boss. An electrical element such as relay is disposed between said starter fixing boss and said starter holding boss, and at least one of the starter fixing boss and said starter holding boss is integrally formed with a fixing boss for fixing the electrical element. 
     According to the outboard motor of the structures mentioned above, it is possible to dispose a starter motor and an oil filter while efficiently utilizing a space, to easily exchange the oil filter from a hull side and to shorten the forward and backward length of the engine, making the outboard motor compact. 
     It is possible to enhance the relative positional precision of the starter motor with respect to a crankshaft and to enhance the flexibility of the mounting position and the mounting operation of the starter motor. The starter motor can reliably be held with a simple structure. 
     Still furthermore, it is possible to dispose other parts around the starter motor while utilizing a space efficiently and enhancing outer appearance, to enhance the strength of part fixing bosses to enhance the resistance to vibration and to reduce the weight. 
     The nature and further characteristic features of the present invention will be made more clear from the following descriptions made with reference to the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the accompanying drawings: 
     FIG. 1 is a left side view showing one example of an outboard motor according to the present invention; 
     FIG. 2 is a left side view of an engine and an engine holder; 
     FIG. 3 is a plan view of the engine viewed from the arrow III in FIG. 2; 
     FIG. 4 is a front view of the engine viewed from an arrow IV in FIG.  2  and shows an embodiment of the invention; 
     FIG. 5 is a front view of a crankcase; 
     FIG. 6 is a left side view of the crankcase viewed from the arrow VI in FIG. 5; 
     FIG. 7 is a plan view of the crankcase viewed from the arrow VII in FIG. 5; 
     FIG. 8 is a transverse sectional view of the crankcase taken along the line VIII—VIII in FIG. 5; 
     FIG. 9 is a transverse sectional view of a crankcase and a starter motor showing a conventional structure; and 
     FIG. 10 is a transverse cross sectional view of a crankcase and a starter motor showing another conventional structure. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A preferred embodiment of the present invention will be explained hereunder with reference to the accompanying drawings. 
     With reference to FIG. 1, showing an outboard motor in a state mounted to a hull, for example, an engine  2  is mounted in an uppermost portion of an outboard motor  1 . The engine is an in-line three-cylinder four-stroke-cycle gasoline engine, for example, and is mounted on a flat-plate like engine holder  8  such that a crankshaft  3  is directed vertically uprightly, and a crankcase  4 , a cylinder block  5 , a cylinder head  6 , and a head cover  7  are disposed in this order from the front side (right in FIG. 1) of the outboard motor  1 . 
     An oil pan  9  is fixed to a lower surface of the engine holder  8 . A drive shaft housing  11  and a gear housing  12  are fixed to a lower portion of the oil pan  9  in this order. The engine  2 , the engine holder  8  and the oil pan  9  are covered with an engine cover  13  for waterproofing. 
     A drive shaft  14  is connected to a lower end of the crankshaft  3  of the engine  2  such that the drive shaft  14  rotates in unison with the crankshaft  3 . The drive shaft  14  extends downward, vertically passes through the engine holder  8 , the oil pan  9  and the drive shaft housing  11  and reaches inside of the gear housing  12 . A propeller shaft  15  is pivotally supported within the gear housing  12  in the horizontal (longitudinal) direction and is provided at its rear end with a screw propeller  16  such that the screw propeller  16  rotates in unison with the propeller shaft  15 . 
     A bevel gear mechanism  17  and a clutch shifter  18  are provided at a portion at which the drive shaft  14  and the propeller shaft  15  are intersecting. The rotation of the drive shaft  14  is transmitted to the propeller shaft  15  through the bevel gear mechanism  17  so that the screw propeller  16  is rotated to generate a propulsion force. The direction of rotation of the drive shaft  14  which always rotates in a constant direction is switched from a normal direction to a reverse direction or vice versa by a clutch shifter  18 , and the rotation is transmitted to the propeller shaft  15  so that forward and backward movements of the outboard motor  1  (i.e. hull) are selected. 
     The outboard motor has a body portion having the above-described structure which is provided, at its front portion, with a clamp bracket  21  fixed to a hull (stern plate) of a boat, ship or like. The clamp bracket  21  is provided with a swivel bracket  23  through a tilt shaft  22  and a steering shaft  24  pivotally supported vertically in the swivel bracket  23 . The steering shaft  24  is provided, at its upper end and lower end, with an upper mount bracket  25  (steering bracket) and a lower mount bracket  26 , respectively, to be integrally rotatable. 
     A pair of left and right upper mount units  27  provided in the vicinity of a front edge of the engine holder  8  are connected to the upper mount bracket  25 . A pair of lower mount units  28  disposed on left and right opposite sides of the drive housing are connected to the lower mount bracket  26 . With this structure, the body of the outboard motor  1  can turn (steer) leftward and rightward around the steering shaft  24  and can tilt up around the tilt shaft  22  with respect to the bracket  21 . 
     FIGS. 2,  3  and  4  are a left side view of the engine  2  and the engine holder  8 , a plan view of the engine  2 , and a front view of the engine  2 , respectively. As shown in these figures, units such as an exhaust system  31 , an electric equipment box  32  and an ignition unit  33  are disposed on the left surface of the engine  2 , for example, and a fuel pump  34  and an intake system  35  are disposed on the right surface of the engine  2 , for example. The intake system  35  comprises a multi-carburetor bracket  37  connected to an intake manifold  36  extending from the cylinder head  6 , three carburetors  38  mounted in the multi-carburetor bracket  37  and arranged vertically and an intake silencer  40  connected to a rear end of each carburetor  38  through an intake pipe  39 . 
     A flywheel  42  is disposed on an upper surface of the engine  2 , and an electric generating unit  43  is provided therein. The flywheel  42  is integrally formed on an upper end of the crankshaft  3  projecting from the upper surface of the engine  2  such that the flywheel  42  rotates in unison with the crankshaft  3 , and a ring gear  44  is provided therearound. The cylinder head  6  is provided at its upper surface with a thermostat housing  45  and an oil injecting port  46 . 
     Further, on a front surface of the engine  2 , a starter motor  48  is disposed in an upper portion of a front surface of the crankcase  4  (hull side) and an oil filter  49  is disposed below the starter motor  48 . The starter motor  48  and the oil filter  49  are disposed so as to be deviated sideways, e.g., left side with respect to an axis C of the crankshaft  3  as shown in FIG. 4. A pinion gear  51  is provided on a main shaft  50  of the starter motor  48  in a manner that if the starter motor  48  is actuated, the pinion gear  51  slides upward and meshes with the ring gear  44  of the flywheel  42  to allow the latter to rotate, thereby starting the engine  2 . 
     With reference to FIGS. 5 to  8 , eight fastening bosses  53  and eight fastening bosses  54  are formed on the front surface of the crankcase  4 . As shown in FIG. 4, these fastening bosses  53  and  54  are fastened to the cylinder block  5  by means of two kinds of fixing bolts  55  and  56 . A pipe-like main oil gallery  58  is formed on a central portion of the front surface of the crankcase  4  substantially along the axis C of the crankshaft  3 , a cup-like filter mount  59  opened forward is provided closer to the left side of a lower portion of the front surface of the crankcase  4 . A filter oil passage  60  connecting between the main oil gallery  58  and the filter mount  59  are formed horizontally. The filter mount  59  is provided with the oil filter  49  which projects forward (i.e. towards the hull). 
     An interior of the crankcase  4  is divided by two partition walls (see FIG.  8 ). A semi-cylindrical crank bearing  63  (see FIG. 7) formed to these partition walls  62  and upper and lower surfaces of the crankcase  4  is aligned with another crankshaft bearing, not shown, formed on the side of the cylinder block  5 , and the crankshaft  3  is rotatably pivotally supported therebetween. 
     Furthermore, the upper portion of the front surface of the crankcase  4  is provided with a pair of starter fixing bosses  65 ,  66  projecting horizontally forward. The pair of the starter fixing bosses  65 ,  66  are formed with screw holes  67 ,  68  directed in the vertical direction (see FIGS.  7  and  8 ). A starter holding boss  70  is formed below the starter fixing bosses  65 ,  66 , i.e., in the vicinity of the central portion of the front surface of the crankcase  4 . The starter holding boss  70  is provided with a semi-cylindrical holding inner peripheral surface  71  and flat fastening seat surfaces  72  and  73  positioned at opposite sides of the holding inner surface  71 . 
     On the other hand, a horizontally spreading fixing flange  75  is provided in the vicinity of the upper end of the starter motor  48 . The fixing flange  75  is mounted on the starter fixing bosses  65 ,  66  of the crankcase  4 . Two fixing bolts  76  directed in the vertical direction pass through bolt holes, not shown, formed to the fixing flange  75  and fastened to the screw holes  67 ,  68  of the starter fixing bosses  65 ,  66 . With this structure, the upper portion of the starter motor  48  is fixed to the crankcase  4 . 
     A lower portion of the starter motor  48  is tightly fitted to the holding inner peripheral surface of the starter holding boss  70  and is fixed by a holding band  78  (see FIGS. 2 and 4) from the forward side. An intermediate inner peripheral surface of the holding band  78  is abutted against an outer peripheral surface of the starter motor  48 , and the opposite ends of the holding band  78  are fastened to the fastening seat surfaces  72 ,  73  of the starter holding boss  70  by the fixing bolt  79 . With this structure, the lower portion of the starter motor  48  is held between the starter holding boss  70  (holding inner peripheral surface  71 ) and the holding band  78 . 
     Other electrical equipments or parts such as PTT relays  81  are disposed in a space between the starter fixing boss  66  and the starter holding boss  70 . The PTT relay  81  is a relay for a PTT apparatus (power tilt trim apparatus) which is not shown. A starter relay  82  is disposed directly below the starter holding boss  70 , for example. 
     As shown in FIGS. 5 and 6, the PTT relays  81  are fastened and fixed to a part fixing boss  83  formed adjacent the portion directly below the starter fixing boss  66  and a part fixing boss  84  formed adjacent the portion directly above the starter holding boss  70  by means of fixing bolts  85  (see FIGS.  2  and  8 ). On the other hand, the starter relay  82  is fastened and fixed to a part fixing boss  86  provided below the starter holding boss  70  by means of fixing boss  87 . An electric equipment box  32  is fastened and fixed to a part fixing boss  88  formed in the vicinity of the directly below portion of the starter holding boss  70  by means of fixing bolt  89  (see FIG.  2 ). 
     The part fixing boss  83  is integrally formed with the starter fixing boss  66  through a short rib  91 . The part fixing boss  84  and the part fixing boss  88  are integrally formed with the starter holding boss  70 . 
     In the outboard motor  1  having the structure mentioned above of the present invention, since the starter motor  48  and the oil filter  49  are respectively arranged at the upper and lower positions on the front surface of the crankcase  4 , it is possible to dispose the starter motor  48  and the oil filter  49  while utilizing the space efficiently. Further, since the oil filter  49  is disposed forward of the engine  2 , the oil filter  49  can be extremely easily exchanged from the hull side, and the maintenance performance of the engine  2  is excellent. In an outboard motor in which the starter motor  48  is not included and the engine is started only by a recoil starter, since the starter motor  48  is not provided above the oil filter  49 , the attaching and detaching operation of the oil filter  49  can be further facilitated. 
     Further, since the starter motor  48  and the oil filter  49  are disposed so as to be deviated sideways in location with respect to the axis C of the crankshaft  3  as viewed from the front side in a state where the starter motor  48  and the oil filter  49  are respectively arranged at the upper and lower positions on the front surface of the crankcase  4  in this manner, the projecting amounts of the starter motor  48  and the oil filter  49  from the front surface of the crankcase  4  are small, and the forward and backward length of the engine  2  is shortened. Therefore, the outboard motor  1  can be made compact. 
     Furthermore, when the starter motor  48  is mounted, the starter fixing bosses  65 ,  66  are horizontally projected from the upper portion of the crankcase  4 , the horizontally spreading fixing flange  75  is provided on the upper end of the starter motor  48 , the fixing flange  75  is mounted on the starter fixing bosses  65 ,  66 , and the fixing flange  75  is fastened and fixed to the starter fixing bosses  65 ,  66  by means of the fixing bolts  76  directed in the vertical direction. Therefore, the axial direction of the crank bearing  63  of the crankcase  4  and the axial directions of the screw holes  67 ,  68  of the fixing bolts  76  coincide with each other, and thus, the crank bearing  63  and the screw holes  67 ,  68  can be formed at the same time. 
     Therefore, when the starter motor  48  is assembled into the engine  2 , the relative positional precision of the starter motor  48  with respect to the crankshaft  3  can be enhanced, and the engagement backlash between the pinion gear  51  of the starter motor  48  and the ring gear  44  around the flywheel  42  can be set to a proper amount. Furthermore, since the positions where the starter fixing bosses  65 ,  66  are formed are less prone to be influenced by the shape and the like of the crankcase  4 , the flexibility of the position of starter motor  48  can be remarkably enhanced. 
     Still furthermore, when the starter motor  48  is assembled, if the fixing flange  75  of the starter motor  48  is placed on the starter fixing bosses  65 ,  66 , the entire weight of the starter motor  48  is supported by the starter fixing bosses  65 ,  66 . Therefore, it is unnecessary to keep holding the starter motor  48  with a hand, and the fixing bolt  76  can be fastened by using both hands. Therefore, the mounting operability of the starter motor  48  can be extremely improved. 
     Further, since the lower portion of the starter motor  48  is held by the starter holding boss  70  provided below the starter fixing bosses  65 ,  66  and the holding band  78  fastened to the starter holding boss  70  by the fixing bolt  79 , it is possible to strongly hold the starter motor  48  with the extremely simple structure. Furthermore, since the holding positions by the starter holding boss  70  and the holding band  78  can be selected along the axial direction of the starter motor  48 , the flexibility of height, at which the starter holding boss  70  is disposed, is enhanced, and the design becomes easy. 
     On the other hand, although there exists a dead space between the starter holding boss  70  and the starter fixing bosses  65 ,  66 , since the PTT relay  81  is disposed in this space, the dead space can be effectively utilized, as well as enhancing the outer appearance. Another part may be disposed in this space other than the PTT relay  81 . 
     Furthermore, the part fixing bosses  83 ,  84  and  88  for fixing the PTT relay  81  and the electric equipment box  32  to the crankcase  4  are integrally formed with the starter fixing boss  66  and the starter holding boss  70 . Therefore, the strong starter fixing boss  66  and the starter holding boss  70  also function as the part fixing bosses  83 ,  84  and  88  which required the strength in the conventional structure, and thus, it is possible to enhance the strength of the part fixing bosses  83 ,  84  and  88  and to increase the resistance to vibration. Still furthermore, since it is unnecessary to increase the thickness of the part fixing bosses  83 ,  84  and  88  for enhancing the strength, this contributes to the reduction in weight. 
     It is to be noted that the present invention is not limited to the described embodiment and many other changes and modifications may be made without departing from the scopes of the appended claims.