Abstract:
An outboard motor adapted to be mounted on a stern of a boat and having a propeller to propel the boat, a power source which produces rotational output, a drive unit including a vertical shaft which transmits the rotational output of the power source to the propeller through a gear mechanism, and an interlock unit which detachably interlocks the power source to the drive unit. The changeable power source includes one of an internal combustion engine, an electric motor and a combination of the engine and the motor. The interlock unit interlocks one of the engine, the motor and the combination of the engine and the motor to the drive unit as the power source for propelling the boat, thereby enabling to freely change its power source as desired in accordance with a user&#39;s current needs and purposes.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   The present application claims priority under 35 USC 119 based on Japanese Patent Application No. 2006-050125 , filed on Feb. 27, 2006 , the entire disclosure of which is incorporated herein by reference. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention relates to an outboard motor, more particularly to an outboard motor whose power source can be freely changed among an internal combustion engine, electric motor and combination thereof. 
   2. Description of the Related Art 
   Among outboard motors, there are known three kinds of outboard motors, i.e., one equipped with an internal combustion engine as its propeller power source, another equipped with an electric motor as its power source and, as taught, for example, by Japanese Laid-Open Patent Application No. Sho 59(1984)-230,894 (page 2, left column, line 9 to 13, FIG. 1, etc.), the other equipped with a combination of an internal combustion engine and an electric motor as its power source (hybrid outboard motor). One of the above three kinds of power sources is mounted on a boat (hull) to be used. 
   However, outboard motor power sources are different in their characteristics each other, for instance the internal combustion engine has good high-speed performance, the electric motor has a characteristic of quietness, and the like. Therefore, there is a demand for easily changing an outboard motor power source to be mounted. 
   SUMMARY OF THE INVENTION 
   An object of this invention is therefore to overcome the foregoing disadvantage by providing an outboard motor whose power source can be freely changed among three kinds of power sources, i.e., an internal combustion engine, electric motor and combination thereof in accordance with purposes. 
   In order to achieve the object, this invention provides an outboard motor adapted to be mounted on a stern of a boat and having a propeller to propel the boat, comprising: a power source which produces rotational output; a drive unit including a vertical shaft which transmits the rotational output of the power source to the propeller through a gear mechanism; and an interlock unit which detachably interlocks one of an internal combustion engine, an electric motor and a combination of the engine and the motor to the drive unit as the power source. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above and other objects and advantages of the invention will be more apparent from the following description and drawings in which: 
       FIG. 1  is a partially sectional view showing an outboard motor according to an embodiment of this invention; 
       FIG. 2  is an enlarged partially sectional view of a region of the engine of the outboard motor shown in  FIG. 1 ; 
       FIG. 3  is a plan view of an engine attachment plate shown in  FIG. 2 ; 
       FIG. 4  is an enlarged partially sectional view showing the vicinity of an interlock unit shown in  FIG. 1 ; 
       FIG. 5  is an enlarged partially sectional view similar to  FIG. 4  but showing the interlock unit shown in  FIG. 4  in its state of un-interlocking the power source and a drive unit; 
       FIG. 6  is a cross-sectional view taken along line VI-VI in  FIG. 4 ; 
       FIG. 7  is a view partially similar to  FIG. 2  but showing the configuration in which the motor is interlocked to the drive unit as the power source; 
       FIG. 8  is a view similar to  FIG. 1  but showing this change of the power source from the combination to the motor; 
       FIG. 9  is a plan view of a motor case cap shown in  FIG. 7 ; 
       FIG. 10  is a view partially similar to  FIG. 2  but showing the configuration in which the engine is interlocked to the drive unit as the power source; and 
       FIG. 11  is a view similar to  FIG. 1  but showing this change of the power source from the combination to the engine. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   An outboard motor according to a preferred embodiment of the present invention will now be explained with reference to the attached drawings. 
     FIG. 1  is a partially sectional view showing an outboard motor according to an embodiment of this invention. 
   The outboard motor is designated by reference numeral  10  in  FIG. 1 . The outboard motor  10  is mounted on the stern (transom)  18  of a boat or hull  16  by means of two stern brackets  14  (only one shown in  FIG. 1 ) equipped with a screw-type clamping device  12 . As shown in the figure, the outboard motor  10  is equipped with an internal combustion engine (power source; hereinafter called “engine”)  20  at its upper portion in the vertical direction. 
     FIG. 2  is an enlarged partially sectional view of a region of the engine  20  of the outboard motor shown in  FIG. 1 . 
   The engine  20  is a spark-ignition, one-cylinder gasoline engine with a displacement of about 50 cc and generates the power output of 1.5 kW, i.e., about 2PS. The engine  20  has its crankshaft  22  aligned parallel to the gravity direction, i.e., in the vertical direction when mounted on the boat  16 . The engine  20  and crankshaft  22  are enclosed by an engine case  24 . A fuel tank  26  is installed near the engine  20  and stores fuel, i.e., gasoline fuel  28  to be supplied to the engine  20 . 
   An electric motor (power source; generator-motor)  30  is installed in the outboard motor  10  vertically downward of the engine  20 . The motor  30  is a DC brushless motor comprising a stator  30   a  and a rotor or output shaft  30   b  and is supplied with voltage from a battery (not shown) disposed at the boat  16  via a battery cable (not shown) and the like to produce an output of several hundred Watts. The electric motor  30  has its output shaft  30   b  aligned parallel to the vertical direction and is enclosed by a motor case  32 . 
   A clutch, more precisely a centrifugal clutch  34  is installed between the engine  20  and the motor  30  and connect/disconnect an output to be transmitted from the engine  20  to the output shaft  30   b . Specifically, the lower end of the crankshaft  22  of the engine  20  and the upper end of the output shaft  30   b  of the motor  30  are connected or combined through the centrifugal clutch  34 . 
   The centrifugal clutch  34  comprises a clutch shoe  34   a  pivotally supported at the lower end of the crankshaft  22  so as to be increased in diameter, a clutch spring (not shown) urging the clutch shoe  34   a  in the direction of reducing the diameter and a clutch outer  34   b  fastened to the output shaft  30   b  of the motor  30  while surrounding the clutch shoe  34   a.    
   When the crankshaft  22  is rotated at a speed exceeding a predetermined rotation speed, the clutch shoe  34   a  is made increased in diameter and pressed onto the inner wall of the clutch outer  34   b  to connect the crankshaft  22  to the output shaft  30   b . Specifically, the engine  20  is started by the motor  30  and after started, when a speed of the engine exceeds the predetermined speed, the motor  30  is rotated by the engine  20  to produce electric energy that is charged by the battery. 
   It should be noted that in this embodiment the engine  20  and electric motor  30  combined via the centrifugal clutch  34  is called the “combination of the engine  20  and electric motor  30 .” 
   The upper end of a vertical shaft (drive unit)  42  is detachably interlocked to the lower end of the output shaft  30   b  of the motor  30  through an interlock unit  40 . Thus the combination of the engine  20  and electric motor  30  is configured so that the motor  30  is located at a position between the engine  20  and the interlock unit  40 . 
   Between the motor  30  and the interlock unit  40  is disposed with an electromagnetic clutch  44  that connects/disconnects transmission of an output from the engine  20  or motor  30  to the interlock unit  40 , vertical shaft  42  and the like. Specifically, the output shaft  30   b  of the motor  30  and the interlock unit  40  are interconnected by the electromagnetic clutch  44 . 
   When the clutch  44  is energized, it connects the output shaft  30   b  to the interlock unit  40 , while, when being de-energized, it cuts off the connection between the output shaft  30  and interlock unit  40 . The clutch  44  and interlock unit  40  are housed in a clutch housing  46  installed downward of the motor case  32 . 
   The foregoing engine case  24 , motor case  32  and clutch housing  46  will be explained. 
   The motor case  32  downward of the engine case  24  has a divided structure of two parts, i.e., an upper motor case  32   a  in which the lower or bottom surface and the center region of the upper surface are opened and a lower motor case  32   b  in which the upper surface and the center region of the lower surface are opened. The divided two parts are fastened by a bolt  50 . The opening formed at the center region of the upper surface of the upper motor case  32   a  is indicated by a symbol  32   a   1 . An engine attachment plate (interlocking member; hereinafter simply called “plate”)  52  is inserted between the engine case  24  and the upper motor case  32   a.    
     FIG. 3  is a plan view of the plate  52  shown in  FIG. 2 . 
   The plate  52  having a doughnut shape is provided with a plurality of, i.e., three holes  52   a  into which bolts (fasteners)  54  (shown in  FIG. 2 ) for connecting the plate  52  and engine case  24  are inserted, and a plurality of, i.e., three holes  52   b  into which bolts (fasteners)  56  (shown in  FIG. 2 ) for connecting the plate  52  and the upper motor case  32   a  are inserted. 
   Screw holes  24   a  are formed at the lower surface of the engine case  24  so as to correspond to the holes  52   a  of the plate  52 , so that they can be engaged with the bolts  54 . Screw holes  32   a   2  are also formed at the upper surface of the upper motor case  32   a  to correspond to the holes  52   b  of the plate  52 , so that they can be engaged with the bolts  56 . 
   The bolts  54  are inserted through the holes  52   a  of the plate  52  into the screw holes  24   a  of the engine case  24  to be engaged therewith, thereby connecting the plate  52  and engine case  24 . Similarly, the bolts  56  are inserted through the holes  52   b  of the plate into the screw holes  32   a   2  of the upper motor case  32   a  to be engaged therewith, thereby connecting the plate  52  and upper motor case  32   a . Thus the engine case  24  is connected to the upper motor case  32   a  through the plate  52 . 
   At appropriate positions, more precisely, on the axes of the screw holes  24   a  of the engine case  24  in the upper surface of the clutch housing  46  are formed with a plurality of, i.e., three holes  46   a  (only one shown in  FIG. 2 ) into which bolts (fasteners)  60  for connecting the clutch housing  46  and lower motor case  32   b  are inserted. Screw holes  32   b   1  are formed at the lower surface of the lower motor case  32   b  so as to correspond to the holes  46   a  of the clutch housing  46 , so that they can be engaged with the bolts  60 . 
   The bolts  60  are inserted through the holes  46   a  of the clutch housing  46  into the screw holes  32   b   1  of the lower motor case  32   b  to be engaged therewith, thereby connecting the clutch housing  46  and lower motor case  32   b.    
   The explanation of  FIG. 1  will be resumed. The vertical shaft  42  is aligned parallel to the vertical direction and supported to be rotatable about the vertical axis within a frame pipe  62  attached downward of the clutch housing  46 . As shown in the figure, a part of the frame pipe  62  and the entire gear case  66  are provided at a location in water, i.e., under the water surface when the outboard motor  10  is attached to the boat  16 . In  FIG. 1 , the symbol W indicates seawater or freshwater. 
   A propeller shaft  70  is supported to be rotatable about the horizontal axis within the gear case  66 . One end of the propeller shaft  70  projects from the gear case  66  to rearward of the outboard motor  10  and is attached with a propeller  72 . A bevel gear  74  is installed on the outer periphery of the propeller shaft  70  and is rotated by engagement with a pinion gear  64 . 
   Thus the output, i.e., rotational output of the motor  30  is transmitted through the electromagnetic clutch  44 , interlock unit  40 , vertical shaft  42 , pinion gear  64  and bevel gear  74  to the propeller shaft  70  to rotate the propeller  72 , thereby producing thrust for driving the boat  16  forward or rearward. 
   The output, i.e., rotational output of the engine  20  is transmitted through the centrifugal clutch  34  to the output shaft  30   b  of the motor  30  and then, like the output of the motor  30 , through the electromagnetic clutch  44 , interlock unit  40 , vertical shaft  42 , pinion gear  64  and bevel gear  74  to the propeller shaft  70  to rotate the propeller  72 , thereby producing thrust for driving the boat  16  forward or rearward. 
   As explained in the foregoing, the outboard motor  10  comprises a hybrid outboard motor that is equipped with the power sources comprising the engine  20 , the motor  30  and a combination of the engine  20  and motor  30 , and with a drive unit for transmitting an output of one of the engine  20  and the motor  30  to drive the propeller  72 , i.e., drive shaft of the propeller  72  (more specifically, vertical shaft  42 , propeller shaft  70  etc.), and is constituted as a relatively small hybrid outboard motor. 
   The outboard motor  10  is equipped with a bar handle or tiller  74  at an appropriate position, precisely at the clutch housing  46 . The free end of the bar handle  74  projects toward the cockpit of the boat  16  so as to be operable for the boat operator, as shown in  FIG. 1 . The frame pipe  62  is supported by the stern brackets  14  to be rotatable about the vertical axis, so that the operator can steer or maneuver the outboard motor  10  left and right by swinging the bar handle  74  laterally. 
   A throttle grip  76  is provided at the forward (free) end of the bar handle  74  (relative to the direction of forward travel of the boat  16 ). The throttle grip  76  can be rotatably operated by the boat operator and is installed with a rotation angle sensor (volume sensor)  80  therein. The rotation angle sensor  80  produces an output or signal proportional to the rotation angle (manipulated variable) of the throttle grip  76  to be inputted to an electronic control unit (ECU)  82  constituted as a microcomputer. Based on the inputted signal, the ECU  82  controls the output of the motor  30  to regulate the speed of the boat  16 . 
   The throttle grip  76  is also connected via a push-pull cable (not shown) to a throttle valve (not shown) of the engine  20 . As a result, the operation of the throttle grip  76  makes the throttle valve open or close to control the engine speed, thereby regulating the boat speed. 
   The bar handle  74  is further equipped with a mode (selector) switch  84  that produces signals in response to instructions inputted by the operator including those to start or stop the power sources (engine  20 , motor  30 ) and send the same to the ECU  82 . The ECU  82  controls the operation of the engine  20 , motor  30 , electromagnetic clutch  44  and the other components in response to the inputted outputs. 
   The interlock unit  40  that interlocks the output shaft  30   b  of the motor  30  with the upper end of the vertical shaft  42 , i.e., the power source with the drive unit, will be explained in detail. 
     FIG. 4  is an enlarged partially sectional view showing the vicinity of the interlock unit  40  shown in  FIG. 1  and  FIG. 5  is an enlarged partially sectional view similar to  FIG. 4  but showing the interlock unit  40  shown in  FIG. 4  in its state of un-interlocking the power source and the drive unit. 
   As shown in  FIGS. 4 and 5 , the interlock unit  40  is provided with a rod (first interlock member)  90  extending from (connected to or formed at) the lower end  30   b   1  of the output shaft  30   b  of the motor  30  (i.e., connected to the power source) and a hollowed stern (second interlock member)  94  connected to the drive unit, i.e., the upper end  42   a  of the vertical shaft  42  through a coupling member  92  to receive the rod  90 . 
   A coupler  46   b  of roughly cylindrical shape is formed near the lower end of the clutch housing  46 . The interior of the coupler  46   b  is formed with a space  96  (shown only in  FIG. 5 ) which receives or accommodates the lower end  30   b   1  of the output shaft  30   b  and the rod  90 . The frame pipe  62  is formed near its upper end with a roughly cylindrical projection  62   a . The interior of the projection  62   a  is formed with a space  98  which receives or accommodates the upper end  42   a  of the vertical shaft  42 , the coupling member  92  and the hollowed stern  94 . 
     FIG. 6  is a cross-sectional view taken along line VI-VI in  FIG. 4 . 
   As shown in  FIG. 6 , the rod  90  is made of a solid body of polygonal (i.e., substantially square) shape when viewed in cross-section. The hollowed stern  94  is a hollow body of similar polygonal shape (i.e., substantially square) when viewed in cross-section. The interior of the hollowed stern  94  is shaped to receive the rod  90 . 
   When establishing the engagement between the rod  90  and hollowed stern  94 , which make up the interlock unit  40 , the output shaft  30   b  of the motor  30  is connected to the vertical shaft  42 . On the other hand, as shown in  FIG. 5 , when the rod  90  is removed from the hollowed stern  94 , the output shaft  30   b  is disconnected from the vertical shaft  42 . The power sources and drive unit are detachably interlocked through the interlock unit  40 . 
     FIG. 7  is a view partially similar to  FIG. 2  but shows the configuration in which the motor  30  is interlocked to the drive unit as the power source. 
   The change of the power source from the combination of the engine  20  and motor  30  to the motor  30  will be explained. 
     FIG. 8  is a view similar to  FIG. 1  but showing this change of the power source from the combination to the motor  30 . 
   The bolt  54  (shown in  FIG. 2 ) is first unfastened and the engine  20  and engine case  24  are removed from the motor  30  and motor case  32  (more precisely the upper motor case  32   a ). As shown in  FIG. 8 , the centrifugal clutch  34  installed between the engine  20  and motor  30  is now split into clutch shoe  34   a  and clutch outer  34   b . Then, a motor case cap  100  is attached to the upper motor case  32   a , more specifically to the plate  52  installed above the upper motor case  32   a.    
     FIG. 9  is a plan view of the motor case cap  100  shown in  FIG. 7 . 
   As shown in  FIG. 7  and  FIG. 9 , the motor case cap  100  has a disc-like shape in plan view and a cup-like shape in cross section to form a recess  100   a  where the clutch outer  34   b  is housed. The cap  100  is formed with three holes  100   b  at the positions corresponding to the screw holes  52   a  formed at the plate  52 . 
   The motor case cap  100  is connected to the plate  52  by inserting a bolt  102  in each of the holes  100   b  of the motor case cap  100  and holes  52   a  of the plate  52  and by fastening it by a nut  104 , as shown in  FIG. 7 . With this, the opening  32   a   1  of the upper surface of the upper motor case  32   a  is surely covered, thereby enabling to prevent seawater or dust from entering inside the outboard motor through the upper motor case opening  32   a   1 . 
   The power source of outboard motor  10  is thus changed from the combination of the engine  20  and motor  30  to the motor  30 . In the change, the interlock unit  40  itself is left as it is and is not needed to be removed. In other words, the interlock unit for interlocking the motor  30  to the drive unit is made same as the interlock unit for interlocking the combination to the drive unit. 
     FIG. 10  is a view partially similar to  FIG. 2  but showing the configuration in which the engine  20  is interlocked to the drive unit as the power source. 
   Next, the change of the power source from the combination of the engine  20  and motor  30  to the engine  20  will be explained. 
     FIG. 11  is a view similar to  FIG. 1  but showing this change of the power source from the combination to the engine  20 . 
   As shown in  FIG. 11 , the engine  20 , engine case  24 , motor  30  and clutch housing  24 , etc., are lifted upward, and the power source is then removed, specifically, the rod  90  formed at the output shaft  30   b  of the motor  30  is removed from the hollowed stern  94  of the vertical shaft  42 . 
   Then, the bolts  54 ,  56 ,  60  (shown in  FIG. 2 ) are all unfastened and the motor  30  and motor case  32  are removed from the engine  20 , engine case  24  and clutch housing  46 . At that time, the centrifugal clutch  34  can be split into the clutch shoe  34   a  and clutch outer  34   b.    
   Then, as shown in  FIG. 10 , the clutch housing  46  is attached to the frame pipe  62  and the power source (engine  20 ) is interlocked to the drive unit through a second interlock unit  40   a.    
   Specifically, an output shaft  120  (for transmitting output from the crankshaft  22  to the vertical shaft  42 ) is rotatably inserted in the clutch housing  46 . The output shaft  120  is formed, at its upper end, with a second clutch outer  34   b   1  that has an almost same shape as the clutch outer  34   b  and at its lower end, with a second rod (first interlock member)  90   a  that has a similar shape to the rod  90 . 
   The centrifugal clutch  34  can be completed if the second rod  90   a  of the output shaft  120  is inserted in the hollowed stern (second interlock member)  94  of the vertical shaft  42  and if the second clutch outer  34   b   1  is connected to the clutch shoe  34   a  of the crankshaft  22 . With this, the rotational output of the engine  20  can be transmitted to the vertical shaft  42  through the centrifugal clutch  34 , output shaft  120  and second interlock unit  40   a.    
   Next, the engine case  24  is connected to the clutch housing  46  by inserting the bolt (fastener)  60  into each of the holes  46   a  of the clutch housing  46  and the holes  24   a  of the engine case  34  and by fastening it. The power source of outboard motor  10  is thus changed from the combination of the engine  20  and motor  30  to the engine  20 . 
   As stated above, the second interlock unit  40   a  for interlocking the engine  20  to the drive unit is made similar in shape as the interlock unit  40  for interlocking the combination (of the engine  20  and motor  30 ) and motor  30  to the drive unit. More specifically, the second interlock unit  40   a  is different from the interlock unit  40  in that the shape of the second rod  90   a  is made similar to the rod  90 . 
   The exemplary embodiment is thus configured to have an outboard motor ( 10 ) adapted to be mounted on a stern of a boat ( 16 ) and having a propeller ( 72 ) to propel the boat, comprising: a power source which produces rotational output; a drive unit including a vertical shaft ( 42 ) which transmits the rotational output of the power source to the propeller through a gear mechanism; and an interlock unit ( 40 ,  40   a ) which detachably interlocks one of an internal combustion engine ( 20 ), an electric motor ( 30 ) and a combination of the engine and the motor to the drive unit as the power source. 
   In the outboard motor, the interlock unit comprises one of a first interlock unit (second interlock unit  40   a ) for interlocking the engine to the drive unit, and a second interlock unit (interlock unit  40 ) for interlocking one of the motor and the combination of the engine and the motor to the drive unit, and the first and second interlock units are made similar in shape. 
   In the outboard motor, each of the first and seconds interlock units comprises a first interlock member (rod  90 ,  90   a ) connected to the power source, a second interlock member (hollowed stern  94 ) connected to the drive unit and a fastener (bolts  54 ,  56   60 ) for detachably fastening the one of the power sources to the drive unit through the first interlock member and the second interlock member. 
   In the outboard motor, the motor ( 30 ) is located between the engine ( 20 ) and the interlock ( 40 ) unit in the combination of the engine ( 20 ) and the motor ( 30 ) when interlocked to the drive unit. 
   In the outboard motor, the motor ( 30 ) is interlocked to the drive unit through the second interlock unit ( 40 ) with the engine ( 20 ) removed. 
   In the outboard motor, the motor ( 30 ) is covered by a motor case cap ( 100 ). 
   The outboard motor further includes: a first clutch ( 44 ) which connects/disconnects the rotational output of the power source (engine  20 , motor  30 ) to be transmitted to the propeller ( 72 ). 
   In the outboard motor, the first clutch comprises an electromagnetic clutch ( 44 ). 
   The outboard motor further includes: a second clutch ( 34 ) disposed between the engine ( 20 ) and the motor ( 30 ) which transmits the rotational output of the engine to the drive unit through an engine output shaft and a motor output shaft, when the engine is operated. 
   In the outboard motor, the second clutch comprises a centrifugal clutch ( 34 ). 
   In the outboard motor, the engine ( 20 ) is started by the motor and when a speed of the engine exceeds a predetermined speed, the motor is rotated by the engine to produce electric energy that is charged by a battery. 
   The outboard motor further includes: a bar handle ( 74 ) installed to be operable by an operator; a throttle grip ( 76 ) provided at the bar handle to be rotatable by the operator to regulate an opening of a throttle valve of the engine. 
   The outboard motor further includes: a rotation angle sensor ( 80 ) installed in the bar handle which outputs a signal indicative of a rotation angle of the throttle grip; and a controller (ECU  82 ) installed inside the throttle grip which inputs the outputted signal of the rotation angle sensor to control operation of the motor in response to the outputted signal of the sensor. 
   In the outboard motor, the bar handle ( 74 ) is further equipped with a mode switch ( 84 ) that produces signal in response to instructions inputted by the operator to start or stop the engine ( 20 ) and the motor ( 30 ), and the controller (ECU  82 ) controls the operation of the engine and the motor in response to the signal of the mode switch. 
   It should be noted that, although the embodiment has been explained to change the power source from the combination of the engine  20  and motor  30  to the engine  20  or motor  30 , it is of course possible to change the power source from the engine  20  or motor  30  to the combination, or to change from the engine  20  to the motor  30  and vise versa. 
   It should also be noted that, although the embodiment explained in the foregoing uses a DC brushless motor as the electric motor  30 , a different type of motor can be used instead. 
   It should further be noted that, although in the foregoing the engine  20  has been said to have a displacement of about 50 cc and the electric motor  30  to have an output of several hundred Watts, these values are non-limitative examples. 
   While the invention has thus been shown and described with reference to specific exemplary embodiments, it should be noted that the invention is in no way limited to the details of the described arrangements; changes and modifications may be made without departing from the scope of the appended claims.