Patent Publication Number: US-6902450-B2

Title: Outboard motor and tiller handle thereof

Description:
TECHNICAL FIELD 
   The present invention relates to an outboard motor comprising a propulsion propeller, an engine for driving the propeller and a tiller handle extending from a main body of the outboard motor toward a watercraft body so that the steering of the watercraft body can be conducted by using the tiller handle. Particularly, the present invention relates to an outboard motor in which the tiller handle is provided with a display device for electrically displaying a state of the outboard motor in response to a result of sensing by various sensors. 
   Further, the present invention relates to a tiller handle of an outboard motor for steering a motor main body which is equipped with a propulsion propeller and a power source for driving the propeller and steerably attached to a watercraft body. Particularly, the present invention relates to a tiller handle of an outboard motor comprising a handle main body supported by a bracket extending from a motor main body toward a watercraft body such that the handle main body is pivotable in an up-down direction and can be held at an arbitrary inclination angle within a prescribed pivot range. 
   BACKGROUND OF THE INVENTION 
   Some outboard motors are equipped with a display device for enabling an operator to recognize an abnormal state of cooling water, lubricating oil, etc of the engine. Particularly, in outboard motors where a tiller handle extending from a main body of the outboard motor to a watercraft body is used in steering the motor main body, it is known not only to provide the display device to a side of the main body of the outboard motor but also to provide the display device to the tiller handle which is closer to the operator, so that the display device is visible by the operator near the outboard motor (see Japanese Patent Application Laid-Open Publication No. 11-208589, for example). 
   Such a display device is generally configured to indicate the abnormality of the outboard motor by turning on a lamp, and has a lens on a surface of the lamp to improve visibility, which provides a certain view angle range. Besides, a liquid crystal display panel may be used in the display device to indicate various information regarding the state of the outboard motor. In such a case also, the display device will have a certain view angle range. 
   When the display device is mounted in a side surface of a housing of the tiller handle in such a manner that its display surface is substantially flush with the side surface of the housing, the operator will see the display surface of the display device obliquely from above and the view angle range of the display device cannot be fully utilized because part of the view angle range below the display surface will be wasted. 
   Meanwhile, in outboard motors where steering of a motor main body equipped with a propulsion propeller and a power source (or engine) for driving the propeller is conducted by using a tiller handle, the tiller handle (more specifically, a handle main body) may be supported by a bracket extending from the motor main body such that the handle main body is pivotable in an up-down direction whereby the handle main body may pivot from an operating position in which a center line of the handle main body extends in a substantially horizontal direction to a collapsed position in which the handle main body extends along the motor main body. 
   In the collapsible tiller handle as above, it is known to connect a base end of the handle main body and a free end of the bracket to each other by a lateral bolt which functions as a pivot shaft, wherein a nut is threadably engaged to the bolt to produce an axial tightening force which in turn can generate a frictional force for holding the handle main body at an arbitrary angle within a predetermined pivot range (see Japanese Patent Application Laid-Open No. 4-218492, for example). 
   In such a tiller handle capable of steadily holding the handle main body, it is desirable that a structure is provided for keeping a predetermined tightening force by the nut for an extended period of time. However, such a structure can increase an axial dimension of the hinge portion, which may undesirably increase a width of the handle. Further, a tightening process in assembly may be cumbersome and thus lower the work efficiency. 
   The tiller handle may be equipped with various component parts, such as a shift lever, for improving operability. In a case where connection members for connecting these component parts to the motor main body, such as Bowden cables and wire harnesses, are drawn out from the handle main body near the bearing portion of the pivot shaft, it is also required to take into account the way of arrangement of the connection members when designing the structure around the pivot shaft. 
   Further, in outboard motors where a steering operation of the motor main body is conducted by using a tiller handle, it is customary to provide a load adjustment device for adjusting a load applied upon the steering operation conducted by an operator using the tiller handle. A known load adjustment device is constituted by a slide plate and a slide resistance adjustor for pressing a friction member against the slide plate to produce a desired slide resistive force, whereby the slide resistive force generated between the slide plate and the slide resistance adjustor along with a steering movement of the motor main body about a steering axis achieves a desired operational load (see Japanese Utility Model Application Laid-Open No. 51-60099, for example). 
   It such a load adjustment device, the slide plate can be attached to one of a member on the motor main body and a member on the attachment bracket, and the slide resistance adjustor is attached to the other of the members by suitable tightening means such as a blot or the like. However, in a structure where the slide plate is bolted to left and/or right side of the member on the motor main body as in the above mentioned conventional outboard motor, a positioning process for aligning a threaded bolt hole in the motor main body with a threaded bolt hole in the slide plate can be cumbersome, resulting in a complicated assembly work and increase in the number of steps required and hence leading to a higher cost. Thus, a structure that can allow easy positioning is desired. 
   Further, in the above slide resistance adjustor for producing a desired slide resistance by pressing the friction member against the slide plate, if a proper positional relationship between the friction member and the slide plate is not achieved in the direction of pressing of the friction member against the slide plate, it becomes difficult to adjust the slide resistive force to a desired value, which would hinder a smooth movement of the slide plate with respect to the slide resistance adjustor. Therefore, it is required to precisely control the attachment position of the slide plate in the direction of pressing, and it will be desirable to provide a structure that can facilitate such control of position of the slide plate. 
   BRIEF SUMMARY OF THE INVENTION 
   In view of such problems of the prior art, a primary object of the present invention is to provide an outboard motor adapted to effectively utilize the view angle range of the display device for electrically display the state of the outboard motor. 
   A second object of the present invention is to provide a handle of an outboard motor comprising a collapsible tiller handle that can pivot around a pivot shaft, wherein the handle can ensure a stable position holding capability for an extended period of time while suppressing increase in the axial dimension that would lead to increase in the handle width, and wherein the handle is adapted to improve efficiency in assembly thereof. 
   A third object of the present invention is to provide an outboard motor which, in an assembly process, can allow easy positioning of the slide plate for constituting the load adjustment device for adjusting a load applied upon a steering operation using the tiller handle, and which can facilitate control of position of the slide plate in the direction of pressing of the slide late. 
   To achieve the object, according to the present invention, there is provided an outboard motor, comprising: a main body ( 4 ) equipped with a propulsion propeller ( 1 ) and a power source ( 2 ) for driving the propeller and steerably attached to a watercraft body ( 3 ); a tiller handle ( 5 ,  71 ,  81 ) extending from the main body of the outboard motor toward the watercraft body for use in steering the main body of the outboard motor; a sensor ( 41 ,  45 ) for sensing a state of the outboard motor; and a display device ( 21 ) for electrically showing the state of the outboard motor according to a result of sensing by the sensor, wherein the display device is provided to the tiller handle such that a display surface ( 27 ) thereof faces in an oblique upward direction. 
   In this way, at least when seen in the side view, the display surface of the display device can be substantially normal to the line of sight of the operator who usually looks down the display obliquely from above, thereby allowing an effective use of the up-down view angle range of the display device. 
   In the above outboard motor, the display device ( 21 ) may be provided on an upper surface ( 26   a ,  72   a ,  82   a ) of a substantially horizontally extending part ( 26 ,  72 ,  82 ) of the tiller handle ( 5 ,  71 ,  81 ). In such a structure, the tiller handle does not interfere with a left-right view angle range of the display device, thus allowing an effective usage of the left-right view angle range of the display device. 
   In the above outboard motor, the display device ( 21 ) may be arranged such that the display surface ( 27 ) thereof faces toward a free end of the tiller handle ( 5 ). In such a structure, the view angle range of the display device can be effectively used if the operator moves away from the normal steering position to various places in the watercraft. 
   In the above outboard motor, the display device ( 21 ) may be placed at a position in the substantially horizontally extending part ( 26 ) of the tiller handle ( 5 ) close to a base end of the tiller handle. 
   In the above outboard motor, the display device ( 21 ) may be arranged such that the display surface ( 27 ) thereof faces toward an operator when the operator is at a normal operating position. In such a structure, the view angle range of the display device can be effective to the operator who may move or change the posture within a vicinity of the normal steering position. 
   In the above outboard motor, the display device ( 21 ) may be located at a position in the substantially horizontally extending part ( 82 ) of the tiller handle ( 81 ) close to a free end of the tiller handle. 
   In the above outboard motor, it is possible that part of an outer surface ( 26   a ,  72   a ,  82   a ) of a housing ( 26 ,  72 ,  82 ) constituting the substantially horizontally extending part of the tiller handle ( 5 ,  71 ,  81 ) protrudes outwardly to form a projection ( 28 ,  73 ,  83 ), and at least part of the display device ( 21 ) is received in the projection. In this way, a space for installing the display device in the housing can be easily obtained even when user-operating parts such as a shift lever or ignition switch are provided to the tiller handle. 
   According to another aspect of the present invention, there is provided a handle of an outboard motor, comprising: a handle main body ( 5 ); a bracket ( 14 ) extending from a motor main body ( 4 ) toward a watercraft body to support the handle main body via a pivot shaft ( 15 ) such that the handle main body is pivotable around the pivot shaft in an up-down direction; a friction member ( 161 ) fitted on the pivot shaft to create a desired frictional force against the pivoting movement of the handle main body in response to a tightening force along an axis of the pivot shaft; and a pair of inner and outer nuts ( 171 ,  172 ) engaged to a threaded portion ( 166 ) formed in the pivot shaft in a mutually pressing state, wherein an outer end surface ( 163   a ) of a bearing portion ( 163 ) on a side where the nuts are disposed is formed with an opening of a bearing bore ( 179 ) to allow the inner nut ( 171 ) to be relatively unrotatably received in the bearing bore, and wherein an intervening member ( 181 ) is disposed in the bearing bore and fitted on the pivot shaft to transmit an axial tightening force produced by the nuts to the friction member. 
   In this way, because the double nut tightening structure can reliably prevent loosening of the nuts and the inner nut is received in the bearing bore, it is possible to ensure a stable tightening force for an extended period of time while suppressing increase in an axial dimension of the joint. Further, the reception of the inner nut in the bearing bore can prevent relative rotation of the nut and thus, in an assembly process, it is only required to engage a tool to a portion of the pivot shaft opposite to the threaded portion with which the nut is engaged in order to carry out the tightening, and thus the assembling efficiency is improved. 
   In the above handle of an outboard motor, it is possible that an outlet ( 174 ) for drawing out a connecting member ( 51 ,  56 ,  58 ) for connecting a component part ( 18 ,  31 ,  32 ,  33 ,  34 ) mounted to the handle main body to a component part in the motor main body is formed in a base portion of the handle main body ( 5 ) at a position near the bearing portion, and the nuts are disposed on a side opposite to the outlet with respect to the bearing portion. In this way, the nuts are disposed on a side opposite to that covered by the connecting member such as a Bowden cable or wire harness, allowing the tightening of the outer nut to be carried out without being hindered by the connecting member. Further, because the inner nut is received in the bearing bore, the height of the nut projecting out from the side surface that is not covered by the connecting member can be minimized, resulting in an improved appearance around the tiller handle. 
   Further according to this structure, since an intervening member is disposed together with the nuts on a side opposite to the outlet for the connecting member, the friction member is accordingly offset toward the outlet for the connecting member. Thus, even when the forwardly extending bracket is offset from a center line of the motor main body for layout reasons, such as that an inlet for allowing the connecting member from the handle main body to be passed into the motor main body need be located lateral to the bracket, bearing sections that substantially achieve the bearing function about the friction member can be offset toward a center line of the motor main body, improving an operability of the handle main body when it is used in steering operations or pivoted in the upward direction. 
   Other and further objects, features and advantages of the invention will appear more fully from the following description. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Now the present invention is described in the following with reference to the appended drawings, in which: 
       FIG. 1  is a side view for showing an overall structure of an outboard motor according to the present invention; 
       FIG. 2  is a top plan view of the outboard motor shown in  FIG. 1 ; 
       FIG. 3  is a top plan view for showing a first embodiment of a tiller handle to which the present invention is applied; 
       FIG. 4  is a side view of the tiller handle shown in  FIG. 3 ; 
       FIG. 5  is a side view for schematically showing component parts relating to the display device and operation parts shown in  FIGS. 3 and 4 ; 
       FIG. 6  is a top plan view for showing a second embodiment of a tiller handle to which the present invention is applied; 
       FIG. 7  is a side view of the tiller handle shown in  FIG. 6 ; 
       FIG. 8  is a top plan view for showing a third embodiment of a tiller handle to which the present invention is applied; 
       FIG. 9  is a side view of the tiller handle shown in  FIG. 8 ; 
       FIG. 10  is a side view for showing the structures around the tiller handle and bracket of  FIG. 1  in detail; 
       FIG. 11  is a top plan view showing the structures around the tiller handle and bracket of  FIG. 1 ; 
       FIG. 12  is a horizontal cross-sectional view for showing the joint between the handle main body and the bracket shown in  FIGS. 10 and 11 ; 
       FIG. 13  is a side view for showing a structure around a load adjustment device according to the present invention.; 
       FIG. 14  is a top plan view showing the structure around the load adjustment device shown in  FIG. 13 ; 
       FIG. 15  is an exploded side view of the load adjustment device shown in  FIG. 13 ; and 
       FIG. 16  is a top plan view showing the slide plate of the load adjustment device of  FIG. 13  in detail. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1  is a side view for showing an overall structure of an outboard motor according to the present invention. This outboard motor comprises a propulsion propeller  1 , an engine (power source)  2  for driving the propeller  1 , a motor main body  4  steerably attached to a watercraft body  3  via an attachment bracket  6 , and a tiller handle  5  extending toward the watercraft body  3  to steer the motor main body  4 . 
   The attachment bracket  6  is coupled to a swivel case (a member on the attachment bracket)  8  so as to be pivotable around a lateral tilt shaft  7 . The swivel case  8  comprises a cylindrical part for pivotally supporting a vertical swivel shaft, and a mount frame (a member on the motor main body)  9  is attached to an upper end of the swivel shaft while a lower mount housing  10  is attached to a lower end of the same. The mount frame  9  and the lower mount housing  10  are fastened to an engine mount case  117  and extension case  118  via oscillation dampers  11 ,  12  consisting of elastic members provided to rearwardly extending bolt portions of the frame  9  and housing  10 , respectively, so that the motor main body  4  can be steered around a center axis (steering axis)  13  of the swivel shaft. The engine mount case  117  is covered by an under cover  119 , over which an engine cover  121  is attached via an extension case  120 . 
   The tiller handle  5  is joined via a handle bracket  14  to the mount frame  9  which is connected to the main body  4  of the outboard motor. The handle bracket  14  supports the tiller handle  5  (more specifically a main body of the tiller handle  5 ) so as to be pivotable around a lateral joint shaft  15 . A joint  116  between the tiller handle  5  and the bracket  14  is provided with a hinge mechanism for allowing the tiller handle  5  to be pivoted upwardly from an angular position shown by solid lines in  FIG. 1  (an operating position), and to be held at an arbitrary inclination angle. In the operating position, a center line of the tiller handle  5  extends in a substantially horizontal direction, and by moving the tiller handle  5  in a left or right direction, the motor main body  4  can be rotated left or right around the center line  13  of the swivel shaft to a desired steering angle. 
     FIG. 2  is a top plan view of the outboard motor shown in FIG.  1 . The tiller handle  5  is disposed such that its direction of extension, which is represented by a center line  19  of a grip  18  provided at a free end of the tiller handle  5 , is inclined with respect to a fore and aft center line  17  of the motor main body  4  in the plan view. An operator A is to sit or stand at a position on a side of the center line  17  of the motor main body  4  opposite to the direction of extension of the tiller handle  5  (right side in this embodiment) and conducts steering operations. At some times the operator may leave the normal steering position and move to other places in the watercraft body  3 . 
     FIG. 3  is a top plan view for showing a first embodiment of a tiller handle according to the present invention.  FIG. 4  is a side view of the tiller handle shown in FIG.  3 . The tiller handle  5  is equipped with a display device  21  for electrically showing a state of the outboard motor. The display device  21  comprises two indicator lamps  22 ,  23  for indicating abnormal lubricating oil pressure and abnormal cooling water temperature, respectively, and each lamp consists of a light emitting diode and is provided with a lens  24  on a front side thereof. 
   The display device  21  is provided on an upper surface  26   a  of a housing (or a part extending in a substantially horizontal direction)  26  of the tiller handle  5  such that a display surface  27  thereof stands obliquely in an upward direction. Particularly, in this embodiment, the display device  21  is located at a part of the housing  26  close to a base end of the handle or on a side close to the motor main body  4  such that the display surface  27  faces toward a free end of the tiller handle  5 , i.e., a center line  30  of the display surface  27  extends in parallel with the direction of extension (or the center line  19 ) of the tiller handle  5  when seen in the top plan view. 
   In this way, as shown in  FIG. 1 , when seen in the side view the display surface  27  of the display device  21  can be substantially perpendicular to the line of sight of the operator A who usually looks down the display surface  27  obliquely from above. This can allow an effective use of the up-down view angle range of the display device  21 , whereby ensuring a favorable visibility even when the operator stands up or moves away from the tiller handle  5  in the frontward direction, for example. Further, as seen in  FIG. 2 , the tiller handle  5  does not interfere with the left-right view angle range of the display device, allowing the left-right view angle range β to be used effectively so that a favorable visibility can be obtained even when the operator A moves laterally in the watercraft body  3  and leaves the normal steering position, for example. 
   As shown in  FIGS. 3 and 4 , the housing  26  of the tiller handle  5  has an approximately rectangular shape in a cross section taken along the lines perpendicular to the center line  19 , and the upper surface  26   a  consists of a flat surface extending substantially in a horizontal direction. The display device  21  is mounted in such a way that a part of the display device  21  is received in a convex portion  28  that consists of an upwardly protruding part of the upper surface  26   a  of the housing  26 . The convex portion  28  has a cross section having a shape of an inverted V when seen in the side view, and its frontal slanting surface is formed with an opening  29  for exposing the display surface  27  of the display device  21 . 
   On a side surface  26   b  of the housing  26  of the tiller handle  5  facing toward the operator, a shift lever  31  for switching between forward and rearward travels and a tilt switch  32  for a tilt action of the motor main body  4  are provided. On a side surface  26   c  of the housing  26  facing away from the operator, an ignition switch (starter switch)  33  is provided. Further, an emergency stop switch  34  for stopping the engine when the operator falls off from the watercraft is located at a position on the upper surface of the housing  26  close to the base end (or joint  116 ). The grip  18  provided at the free end of the tiller handle  5  is to be used by the operator when conducting steering operations, and rotation thereof around the center line can adjust throttle opening. 
     FIG. 5  is a side view for schematically showing component parts related to the display device and user-operating parts shown in  FIGS. 3 and 4 . The lubricating oil pressure abnormality indicator lamp  22  (see  FIGS. 3 and 4 ) in the display device  21  is electrically connected to an oil pressure switch (sensing means)  41  via a lead wire in a wire harness  58 . The oil pressure switch  41  senses the pressure of the lubricating oil suctioned from an oil pan  43  and delivered to a cylinder head and the like in the engine  2  by an oil pump  42 , and turns on to lighten the lubricating oil pressure abnormality indicator lamp  22  when the lubricating oil pressure becomes below a prescribed value. 
   The indicator lamp  23  (see  FIGS. 3 and 4 ) for indicating the cooling water temperature abnormality is electrically connected to a thermoswitch (sensing means)  45  disposed within a water jacket of the engine  2  via a lead wire in the wire harness  58 . The thermoswitch  45  senses the temperature of the cooling water taken into the water jacket of the engine  2  by a cooling water pump  46  through an inlet  47  located at a lower part of the motor main body  4 , and turns on to lighten the cooling water temperature abnormality indicator lamp  23  when the cooling water temperature becomes beyond a predetermined value. 
   The shift lever  31  is mechanically connected to a gear-clutch mechanism  54 , which is coupled to a driving shaft  55  vertically extending from the engine  2 , via a shift cable  51  ( FIGS. 3 and 4 ) and a shift rod  52  so that forward and rearward tilting actions of the shift lever  31  from a neutral position can cause the gear-clutch mechanism  54  to change the rotational direction of a propeller shaft  53 . The grip  18  ( FIGS. 3 and 4 ) at the end of the tiller handle  5  is mechanically connected to a throttle valve  57  inside the motor main body  4  via a throttle cable  56  (see  FIGS. 3 and 4 ) so that rotating operation of the grip  18  can adjust the opening degree of the throttle valve  57 . 
   The tilt switch  32  is electrically connected to a switch valve  60  of a hydraulically expandable tilt cylinder  59  via a lead wire in the wire harness  58 . The ignition switch  33  is electrically connected via a lead wire in the wire harness  58  to a starting switch of a starter motor mounted in the motor main body  4 . Further, the emergency stop switch  34  (see  FIGS. 3 and 4 ) is electrically connected via a lead wire within the wire harness  58  to a CDI unit  62  disposed in the motor main body  4 . These electric component parts are supplied with electric power by an electric generator  64  provided adjacent to a flywheel  63 . 
     FIG. 6  is a top plan view for showing a second embodiment of a tiller handle according to the present invention.  FIG. 7  is a side view of the tiller handle shown in FIG.  6 . In a manner similar to the first embodiment described above, the display device  21  is disposed in a projection  73  formed on an upper surface  72   a  of a housing  72  such that the display surface  27  stands obliquely in the upward direction. In this embodiment, however, unlike the first embodiment, the display device  21  is located at an intermediate portion of the housing  72  in a direction along the center line  19  such that the display surface  27  faces toward the operator ( FIG. 2 ) at the normal steering position. Particularly in this embodiment, when seen in the top plan view, the center line  30  of the display surface  27  extends obliquely at an angle with respect to the direction of extension (or center line  19 ) of the tiller handle  71  so that the display surface  27  faces obliquely in the forward direction toward the operator. 
     FIG. 8  is a top plan view for showing a third embodiment of a tiller handle according to the present invention.  FIG. 9  is a side view of the tiller handle shown in FIG.  8 . In this embodiment also, like the first and second embodiments described above, the display device  21  is disposed in a projection  83  formed on an upper surface  82   a  of a housing  82  such that the display surface  27  stands obliquely in the upward direction. Further, in a manner similar to the second embodiment, the display device  21  is arranged such that the display surface faces toward the operator. In this embodiment, however, unlike the second embodiment, the display device  21  is located near the grip  18  provided at the free end of the housing  82 . Thus, the display device  21  is arranged such that when seen in the top plan view, the center line  30  of the display surface  27  extends substantially perpendicularly to the direction of extension (or center line  19 ) of the tiller handle  81  so that the display surface  27  faces in a lateral direction toward the operator. 
   In the above embodiments, the display device comprises two LED indicator lamps for indicating abnormality in the lubricating oil pressure and cooling water temperature, but the display device of the present invention may not be limited to those for indicating such component parts abnormalities, and can be used for displaying an operational state such as a traveling speed or engine rotation speed or information regarding the motor main body such as a tilt/trim angle. Further, the display device may comprise display means other than LEDs, and may comprise a display such as a liquid crystal display (LCD) or a Vacuum Fluorescent Display (VFD). Such displays can show various information in a readily understandable manner by using numeral information and/or changing lightness, color, color saturation, and/or brightness, for example. 
   Thus, according to the present invention, the display device can be arranged with its display surface facing in an oblique upward direction, thereby making it possible to effectively utilize the up-down view angle range of the display device. Particularly, when the display device is disposed on an upper surface of a substantially horizontally extending part of the tiller handle, it becomes also possible to effectively utilize the left-right view angle range of the display device. Further, when the display device is received in a projection consisting of a protruding part of the upper surface of the housing, a space for mounting the display device in the housing can be easily ensured. 
     FIG. 10  is a side view for showing the tiller handle (or handle main body) and handle bracket shown in  FIG. 1  in detail together with their surrounding structure. The handle bracket  14  is fixed to a front end of the mount frame  9  with a bolt  122 . Between the swivel case  8  and the mount frame  9  is provided a load control device  123  for adjusting an operation load applied to a steering operation using the tiller handle  5  in such a manner that horizontal rotation of an operation lever  124  can increase/decrease a slide resistance to achieve a desired operation load. The slide resistance may be adjusted so as to lock the steering movement of the motor main body  4  to thereby fix the motor main body  4  at a desired steering angle. 
     FIG. 11  is a top plan view of the structure around the handle main body and bracket shown in FIG.  10 . The tiller handle  5  is arranged so that its direction of extension represented by a center line  131  of the grip  18  at the free end thereof is inclined with respect to a fore-and-aft direction center line  132  of the motor main body  4  when seen in the top plan view. The operator is to sit or stand at a position on a side of the center line  132  of the motor main body  4  opposite to the direction of extension of the tiller handle  5  (left side in this drawing) to conduct steering operations. 
   The handle bracket  14  extends in an upward oblique direction when seen in the side view as shown in  FIG. 10 , and in the top plan view, it is seen that a base end portion  14   a  of the bracket  14  is connected to the mount frame  9  with its center line being aligned with the center line  132  of the motor main body  4  while a free end portion  14   b  of the same extends forwardly with its center line being offset from the center line  132  of the motor main body  4 . 
   As shown in  FIGS. 10 and 11 , the shift cable  51 , throttle cable  56  and wire harness  58  (connecting members) for connecting the component parts provided on the tiller handle  5  to associated parts in the motor main body  4  are drawn out through an outlet  174  formed in a rear end of the housing  26  of the tiller handle  5  and then, through an inlet  175  formed in a front end of the extension case  120  of the motor main body  4 , passed into the inside of the motor main body  4 . The inlet  175  is positioned lateral to the bracket  14  so that when the tiller handle  5  is pivoted in the up-down direction as shown in  FIG. 1 , the shift cable  51 , throttle cable  56  and wire harness  58  bend appropriately so as not to hinder the pivoting action of the tiller handle  5 . Further, in order not to deteriorate the aesthetic appearance around the tiller handle  5 , the inlet  175  is positioned as close to the bracket  14  as possible to minimize the length of exposed part of the connecting members. 
     FIG. 12  is a horizontal cross-sectional view for showing in detail the joint between the tiller handle and bracket shown in  FIGS. 10 and 11 . The joint  116  between the tiller handle  5  and bracket  14  comprises bushes (friction members)  161  that are fitted onto the pivot shaft  15  and, in response to an axial tightening force, produce a desired frictional force for stably holding the tiller handle  5  at an arbitrary inclination angle within a predetermined pivot range. 
   The pivot shaft  15  connects together the tiller handle  5  and the bracket  14  by passing through a bearing portion  162  of the tiller handle  5  and a pair of bearing portions  163 ,  164  of the bracket  14 . One end of the pivot shaft  15  is formed with a head portion  165  having a hexagonal cross-section while the other end of the same is formed with a threaded portion  166 . The bearing portion  162  of the tiller handle  5  is shaped to have a convex profile and the pair of bearing portions  163 ,  164  of the bracket  14  protrude to define a concave profile therebetween so that the bearing portion  162  of the tiller handle  5  can be axially interposed between the bearing portions  163 ,  164  of the bracket  14 . It should be noted that one bearing portion  163  has a larger width than the other bearing portion  164 . 
   The bushes  161  each comprise an axially extending portion  161   a , which has a cylindrical shape and through which the pivot shaft  15  is passed, and a flange-shaped, radially extending portion  161   b  provided at one end of the axially extending portion  161   a . The bushes  161  are formed of a synthetic resin material that can produce a desired frictional force in conjunction with associated members. A pair of such bushes  161  are fitted into respective openings of a bearing bore  168  formed in the bearing portion  162  of the tiller handle  5 . 
   A pair of inner and outer nuts  171 ,  172  are engaged with the threaded portion  166  of the pivot shaft  15  wherein the nuts  171 ,  172  are pressed against each other and function in a double-nut fashion to lock the engagement. Particularly, in this embodiment, the nuts  171 ,  172  are provided on a side opposite to the outlet  174  for the shift cable  51 , throttle cable  56  and wire harnesses  58  (connecting members). The nuts  171 ,  172  each have a hexagonal cross-section. The head portion  165  of the pivot shaft  15  is partially received in a recess  177  formed in an end surface surrounding an opening of a bearing bore  176  of the bearing portion  164  disposed on a side opposite to the nuts  171 ,  172  such that the head portion  165  can rotate relative to the bearing portion  164 . 
   An outer end surface  163   a  of the bearing portion  163  disposed on a side adjacent to the nuts  171 ,  172  is formed with an opening of a bearing bore  179  adapted to unrotatably receive the inner nut  171 . Further, a collar (intervening member)  181  is disposed in the bearing bore  179  and fitted over the pivot shaft  15  to transmit the tightening force of the nut  171  to the bushes (friction members)  161 . A nut receiving portion  182  of the bearing bore  179  for receiving the inner nut  171  therein has a hexagonal cross-section complementary to that of the nut  171 . The collar  181  has a cylindrical shape and is received in a collar receiving portion  183  of the bearing bore  179  wherein the collar receiving portion  183  has a circular cross-section to allow relative rotation of the collar  181 . It should be noted that the nut receiving portion  82  if provided with an abundant axial dimension so as not to limit an axial movement of the nut  71  at the tightening process 
   A washer (wave washer)  185  is interposed between the nut  171  and the collar  181 , while a washer (flat washer)  186  is interposed between the collar  181  and the bush  161 . Further, a washer (flat washer)  187  is interposed between the bearing portion  164  and the head portion  165  of the pivot shaft  15 . 
   The tiller handle  5  can be made by casting an aluminum alloy material such that the housing  26  and the bearing portion  162  are unitary. Also, the bracket  14  as well as the collar  181  can be preferably made by casting an aluminum alloy material. 
   In the hinge structure constructed as above, when the head portion  165  of the pivot shaft  15  is turned with a prescribed torque in a tightening direction with the nut  171  being fitted in the bearing bore  179 , the tightening force is applied to the washer  186  via the collar  181 , whereby the washer  186 , radially extending portions  161   b  of the bushes  161 , side surfaces of the bearing portion  162  of the tiller handle  5 , and side surface of one bearing portion  164  of the bracket  14  are pressed with each other. Also, the inner surface of the bearing bore  168  of the tiller handle  5 , axially extending portions of the bushes  161 , and outer surface of the pivot shaft  15  are pressed with each other. These create a frictional holding force for retaining the tiller handle  5  against a rotating force produced by the weight of the tiller handle  5 . The tiller handle  5  may be rotated smoothly if an operational rotating force beyond the frictional holding force is applied to the tiller handle  5 . 
   In an assembly process, the bushes  161  are fitted in the bearing portion  162 , which is then interposed between the bearing portions  163 ,  164  of the handle bracket  14  so that the bearing bores  168 ,  176  and  179  are aligned with each other, and further, the washer  186  is fitted in a position. The collar  181  and the inner nut  171  are fitted in the bearing bore  179  from the opening in the outer end surface  163   a . Then, the pivot shaft  15  is inserted from the side on the bearing portion  164  and rotated to tighten the structure with a tool engaged to the head portion  165  of the pivot shaft  15 . The tightening force is adjusted to provide an appropriate resist force against a rotating operation. After the adjustment of the tightening force, the outer nut  172  is tightened to create a double nut effect for maintaining the desired tightening force for an extended period of time. 
   In this hinge structure, bearing sections for substantially achieving the bearing function are formed substantially symmetrically with respect to a center line  191  of the bearing portion  162  of the tiller handle  5  fitted with the bushes  161 . Specifically, in the bearing portion  162  of the tiller handle  5 , a part along the extension of the bushes  161  constitutes a bearing section which extends for about the entire length thereof. In one bearing portion  164  of the bracket  14 , a part excluding the recess  177  for receiving the head portion  165  of the pivot shaft  15  constitutes the bearing section. In the other bearing portion of the bracket  14 , a part which the collar  181  extends along but the threaded portion  166  of the pivot shaft  14  does not overlap constitutes a bearing section. 
   The bearing sections as a whole are offset from a center line  192  of the joint  116  toward the outlet  174  for the cables  51 ,  56  and wire harness  58  or toward the center line  132  of the motor main body as a result that the collar  181  as well as the nuts  171 ,  172  are provided on the side opposite to the outlet  174 . 
   Thus, according to the present invention, the double nut tightening structure prevents the loosening of the nuts, and the inner nut is received in the bearing bore whereby the stable handle holding capability can be ensured for an extended period of time while suppressing increase in the axial dimension which would in turn increase the handle width. Further, the degree of projection of the nut from the side surface of the bearing portion can be minimized, thereby allowing a better appearance around the tiller handle. Also, because the intervening member as well as the nuts are provided on the side opposite to the outlet for the connecting members, it is possible to bring the bearing sections, which substantially carry out the bearing function in the joint, closer to the center line of the motor main body, whereby improving the operability of the tiller handle when it is used in steering operations or pivoted in the upward direction. 
     FIG. 13  is a side view showing a structure around a load adjustment device according to the present invention in detail.  FIG. 14  is a top plan view of the structure around the load adjustment device shown in  FIG. 13. A  load adjustment device  123  for adjusting an operational load in the steering operation conducted using the tiller handle  5  is provided between the swivel case  8  and the mount frame  9 . The load adjustment device  123  comprises a slide plate  222  and a slide resistance adjustor  224  for producing a desired slide resistive force by pressing a friction pad (friction member)  223  against the slide plate  222 . The slide plate  222  is attached to one (mount frame  9  herein) of the swivel case  8  and the mount frame  9 , which can rotate relative to each other around the center axis  13  of the swivel shaft, and the slide resistance adjuster  224  is attached to the other (swivel case  8  herein). 
   The slide plate  222  can be obtained by cutting a metallic plate made of stainless steel or the like into a prescribed shape, and bending it. The friction pad  223  is made of a synthetic resin material. Particularly, the friction pad  223  can be preferably made of base fibers impregnated with resin matrix and cured/shaped into a prescribe form, such as aramid fibers and graphite fibers impregnated with phenol resin. 
   As shown in  FIG. 14 , the slide plate  222  has a main body  226  formed with an arcuate slot  225  about the center line  13  of the swivel shaft, and a pair of left and right attachment portions  229 ,  230  respectively bolted to a pair of left and right base portions  227 ,  228  provided to a front end of the mount frame  9 . The attachment portions  229 ,  230  extend out from the main body  226  and are bend in a crank-like shape, as shown in FIG.  13 . 
     FIG. 15  is an exploded side view showing the load adjustment device of FIG.  13 . The slide resistance adjustor  224  is mounted on a bearing surface  232  provided in a front end portion of a top surface of the swivel case  8 , and comprises: a pair of friction pads (friction members)  223  vertically interposing the main body  226  of the slide plate  222  therebetween; a self-lock type nut  234  for threadably engaging with a stud bolt  233  embedded in a central portion of the bearing surface  232 ; an operation lever  124  coupled to the nut  234  so as not to be rotatable relative to the nut  234  and used to adjust the tightening force exerted by the nut  234 ; and a nylon washer  236  interposed between the operation lever  124  and the nut  234 . Thus, by pivoting the operation lever  124  left or right, it is possible to vary the pressure of the friction pads  223  against the slide plate  222 , and accordingly increase or decrease the slide resistive force to achieve a desired operational load. The slide resistive force may be so adjusted to restrain the steering movement of the motor main body  4  to thereby fix the motor main body  4  at a desired steering angle. 
   The slide plate  222  is secured to the base portions  227 ,  228  formed in the front end of the mount frame  9  in such a manner that the main body  226  is disposed in a plane perpendicular to the center line  13  of the substantially vertical swivel shaft. Further, the top surface (or bearing surface  232 ) of the swivel case  8  to which the slide resistance adjustor  224  is mounted is also disposed in a plane perpendicular to the center line  13  of the substantially vertical swivel shaft, whereby the friction pads  223  are pressed against the main body  226  of the slide plate  222  in a substantially vertical direction. Thus, if the slide plate  222  were rotated around the center line  13  of the swivel shaft together with the steering movements of the motor main body  4 , the state of pressed contact of the friction pads  223  against the main body  226  of the slide plate  222  would not change. 
   When the slide plate  222  is attached to the base portions  227 ,  228  provided to the mount frame  9 , the attachment portions  229 ,  230  of the slide plate  222  and the base portions  227 ,  228  are brought into abutment such that their abutment surfaces  241 ,  242  for defining a transverse (or horizontal) position contact each other and their abutment surfaces  243 ,  244  for defining a lengthwise (or vertical) position contact each other, to thereby achieve positioning of the slide plate  222 . In the slide plate  222 , the abutment surface  241  for defining a transverse position is formed on a rear side of a lengthwise portion (or vertical portion)  246  of each of the attachment portions  229 ,  230 , which makes an L-shape when seen in the side view, while the abutment surface  243  for defining a lengthwise position is formed on an underside of a transverse portion (or horizontal portion)  247  of the same. In each of the base portions  227 ,  228 , the abutment surface  242  for defining a transverse position is formed on a frontal side while the abutment surface  244  for defining a lengthwise position is formed on an upper side. 
   The upper side abutment surfaces  244  of the base portions  227 ,  228  are each formed with a bolt receiving threaded hole  250  into which a bolt  249  for securing the attachment portions  229 ,  230  of the slide plate  222  to the base portions  227 ,  228  is threadably received, and correspondingly, the transverse portion  247  of each of the attachment portions  229 ,  230  is formed with a bolt passage hole  251 ,  252  through which the bolt  249  is passed. 
   When the abutment surfaces  241 ,  243  of the attachment portions  229 ,  230  of the slide plate  222  are brought into contact with the abutment surfaces  242 ,  244  of the base portions  227 ,  228 , the position of the slide plate  222  with respect to the base portions  227 ,  228  is determined by the two pairs of surfaces, and thus, by just adjusting the position in a left-right direction along the abutment surfaces  241 - 244 , it is possible to bring the slide plate  222  to an attachment position where the bolt receiving threaded holes  250  of the base portions  227 ,  228  are aligned with the bolt passage holes  251 ,  252  of the slide plate  222 . Further, when the base portions  227 ,  228  and the slide plate  222  are secured to each other by the bolts  249 , the abutment surfaces  243 ,  244  serve to define the lengthwise (or vertical) attachment position of the slide plate  222 , and hence define the attachment position of the friction pads  223  of the slide resistance adjustor  224  in the direction of pressing, whereby allowing the slide plate  222  to be assembled with the slide resistance adjustor  224  with high precision. 
     FIG. 16  is a top plan view showing the slide plate of the load adjustment device of  FIG. 13  in detail. If a center line  254  of the arcuate slot  225  provided to the slide plate  222  is significantly displaced from a center of the slide resistance adjustor  224 , a component part of the slide resistance adjustor  224  inserted into the slot  225  will contact a wall defining the slot  225  and thus a smooth movement will be hindered. Therefore, after the slide plate  222  is preliminarily secured by the bolts  249 , the transverse attachment position of the slide plate  222  is fine adjusted so that the center line  254  of the slot  225  rests on an arc extending around the center line  13  of the swivel shaft. 
   The transverse fine adjustment of attachment position of the slide plate  222  is allowed by an adjustment margin provided by a space between each of bolt passage holes  251 ,  252  formed in the attachment portions  229 ,  230  of the slide plate  222  and a shaft of the respective bolts  249 , and can be carried out in a state that the slide plate  222  is preliminarily fixed by the preliminary tightened bolts  249 , whereby permitting quick and precise adjustment. 
   More specifically, the bolt passage hole  252  formed in one attachment portion  230  of the slide plate  222  assumes a circular shape having a slightly larger diameter than an outer diameter of the shaft of the bolt  249  to create a predetermined play between the passage hole  252  and the shaft of the bolt  249 , while the bolt passage hole  251  formed in the other attachment portion  229  has an oblong shape extending in the fore-and-aft direction, so that by pivoting the slide plate  222  around the bolt  249  associated with the attachment portion  230 , the fine adjustment of transverse position of the slide plate  222  can be achieved. Preferably, the bolt passage hole  251  has an oval shape having linear longitudinal side walls, or alternatively, has arcuate longitudinal side walls extending around the other bolt passage hole  252 . 
   Thus, according to the present invention, the position of the slide plate with respect to the base portions can be determined by two pairs of surfaces, and thus, by just adjusting the position in a direction along the abutment surfaces, the slide plate can be brought to a predetermined attachment position, whereby reducing the assembly time as well as manufacturing cost. Further, the abutment surfaces can also define the attachment position of the slide plate in a direction corresponding to the direction of pressing of the friction members against the slide plate, to thereby facilitate control of the attachment position of the slide plate in the direction of pressing. This can considerably contribute to achieving an appropriate amount of operational load and smooth steering operation. 
   Although the present invention has been described in terms of preferred embodiments thereof, it is obvious to a person skilled in the art that various alterations and modifications are possible without departing from the scope of the present invention which is set forth in the appended claims.