Patent Publication Number: US-2023144964-A1

Title: Suspension structure for outboard motor and outboard motor

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of Japanese Patent Application No. 2021-184080, filed Nov. 11, 2021, which is hereby incorporated by reference herein in its entirety. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a suspension structure for an outboard motor and an outboard motor. 
     2. Description of the Related Art 
     As disclosed in Japanese Laid-open Patent Publication (Kokai) No. 2019-107995, a suspension structure for suspending an outboard motor main body to a hull is known. A suspension structure typically includes a clamp bracket to be fixed to a hull, a tilt shaft attached to the clamp bracket, and a swivel bracket turnably attached to the clamp bracket though the tilt shaft. An outboard motor main body is fixed to the swivel bracket. This arrangement allows the outboard motor main body to be turnable about the tilt shaft and an angle of inclination to the clamp bracket (to the hull) to be changeable. 
     A lateral load may be applied to the lower portion of the outboard motor main body during navigation. For example, a leftward or rightward water pressure may be applied to the propulsion device when the hull turns. Further, a lateral load may be applied when the hull leaves the surface of water and lands on water in a large swell. 
     For example, according to Japanese Laid-open Patent Publication (Kokai) No. 2001-88787 A, it is considered that if a lateral load is applied to the lower portion of the outboard motor, a large bending moment due to the lateral load acts on the swivel bracket through the mount. Simply increasing the member strength in order to increase the strength of the swivel bracket results in an increase in the overall weight of the suspension structure, and thus there is room for improvement. 
     SUMMARY OF THE INVENTION 
     Preferred embodiments of the present invention provide suspension structures for outboard motors each having an increased strength while significantly reducing or preventing an increase in the weight thereof. 
     According to a preferred embodiment of the present invention, a suspension structure for an outboard motor includes a clamp bracket to be attached to a hull, a main body support having a lowest position in a tilt-down state among portions supporting an outboard motor main body except for the clamp bracket, and a coupling fixed to the main body support and supported turnably about a tilt shaft at a first position and a second position in an axial direction of the tilt shaft, wherein the main body support is between the first position and the second position and parallel to the axial direction of the tilt shaft, and when the outboard motor main body is in the tilt-down state, the main body support is lower than the first position and the second position, and an imaginary triangle is defined by the first position, the second position, and the main body support as vertices when viewed from a rear. 
     According to this configuration, for example, when the main body support receives a thrust force parallel to the axial direction of the tilt shaft, a compressive force acts on the coupling between the main body support and one of the first position and the second position, and a tensile force acts on the coupling between the main body support and the other of the first position and the second position. Thus, it is less necessary to increase the member strength of the coupling in order to cope with a bending stress. Therefore, the strength of the suspension mechanism is increased while significantly reducing or preventing an increase in the weight thereof. 
     The above and other elements, features, steps, characteristics and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiments with reference to the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a perspective view of a marine vessel to which a suspension structure for an outboard motor is applied. 
         FIG.  2    is a perspective view of the suspension mechanism (in a tilt-down state). 
         FIG.  3    is a perspective view of the suspension mechanism (in a tilt-up state). 
         FIG.  4    is a side view of the suspension mechanism from the left thereof (in a tilt-down state). 
         FIG.  5    is a side view of the suspension mechanism from the left thereof (in a tilt-up state). 
         FIG.  6    is a rear view of a main portion of the suspension mechanism (in a tilt-down state). 
         FIG.  7    is an enlarged side view of the periphery of an upper pivot. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. 
       FIG.  1    is a perspective view of a marine vessel  10  to which a suspension structure for an outboard motor according to a preferred embodiment of the present invention is applied. The marine vessel  10  includes a hull  11 , a steering wheel  12 , a remote controller  13 , and an outboard motor  100 . The outboard motor  100  includes an outboard motor main body  101  and a suspension mechanism  200  (described below with reference to  FIG.  2    and other figures) supporting the outboard motor main body  101 . The outboard motor main body  101  is attached to a transom  14  of the back portion of the hull  11  through the suspension mechanism  200 . 
     In the following description, unless otherwise specified, front, back, left, and right are referred to in a state in which a steering axis  41  ( FIGS.  4  and  6   ) extends vertically and the outboard motor  100  does not incline left or right with respect to the hull  11  as a reference state. In the reference state, the left-and-right direction indicates a left-and-right direction when the marine vessel  10  is viewed from the rear. Reference signs F, B, L, and R in the drawings represent front, back, left, and right, respectively. For convenience, it is assumed that the state in which the steering axis  41  extends vertically belongs to a tilt-down state of the outboard motor  100 . 
     The steering wheel  12  is provided to steer the hull  11 . In response to operation of the steering wheel  12  by a vessel operator of the marine vessel  10 , the outboard motor main body  101  turns left or right with respect to the hull  11 . Operation of the remote controller  13  by the vessel operator enables the outboard motor  100  to switch a state thereof (shift-change) to moving forward, moving backward, or neutral. The outboard motor main body  101  includes an engine  1  and a propulsion device including a propeller  15 . The engine  1  is provided with a throttle valve (not shown). The vessel operator is able to adjust the opening of the throttle valve by operating the remote controller  13 . The output of the outboard motor  100  is able to be adjusted by adjusting the opening of the throttle valve. 
       FIGS.  2  and  3    are perspective views of the suspension mechanism  200 .  FIGS.  4  and  5    are side views of the suspension mechanism  200  from the left thereof.  FIGS.  2  and  4    show the outboard motor  100  in the tilt-down state, and  FIGS.  3  and  5    show the outboard motor  100  in a tilt-up state. Note that  FIGS.  4  and  5    also show a lower case  38  and an exhaust guide  39  included in the outboard motor main body  101 . In  FIG.  3   , a pair of frames  31 L and  31 R is not shown. In  FIG.  4   , the left frame  31 L is not shown. 
     As shown in  FIG.  4   , hereinafter, a direction parallel to the steering axis  41  is defined as a Z direction. In particular, with the outboard motor  100  in the tilt-down state, the +Z direction is upward and the −Z direction is downward. 
     As shown in  FIGS.  2  to  5   , the suspension mechanism  200  includes, as main elements, a swivel bracket  30 , the pair of frames  31 L and  31 R, a pair of clamp brackets  24 L and  24 R, a pair of side swivel brackets  29 L and  29 R, and a power tilt and trim (PTT) cylinder  25 . Note that the frames  31 L and  31 R may be considered as elements of the outboard motor main body  101 . The PTT cylinder  25  includes a cylinder main body  26  and a rod  27 . 
     As shown in  FIGS.  2  and  4   , a mount holder  32  is fixed to the respective front lower portions of the frames  31 L and  31 R with the outboard motor main body  101  in the tilt-down state. The mount holder  32  holds the lower mount  33 , and is preferably U-shaped or substantially U-shaped in a side view. The mount holder  32  pinches the lower mount  33  in the direction of the steering axis  41  (Z direction). The lower mount  33  functions as a main body support supporting the outboard motor main body  101 , and as a single main load receiver mainly receiving the weight of the outboard motor main body  101 . Among the elements supporting the outboard motor main body  101 , the lower mount  33  has the lowest position, except for the clamp brackets  24 L and  24 R, when the outboard motor main body  101  is in the tilt-down state. The lower mount  33  holds a lower pivot  34  ( FIG.  4   ). 
     With the outboard motor main body  101  in the tilt-down state, an upper pivot  35  (held portion) is higher in position (in the +Z direction) than the lower mount  33 . The lower pivot  34  and the upper pivot  35  function as a steering axis. That is, a drive shaft (not shown) passes through the hole in the lower pivot  34  and the hole in the upper pivot  35 . The steering axis  41  is the center line of the pivots  34  and  35 , and coincides with the axis of the drive shaft. Details of the upper pivot  35  will be described below with reference to  FIG.  7   . 
       FIG.  6    is a rear view of a main portion of the suspension mechanism  200 .  FIG.  6    shows the outboard motor  100  in the tilt-down state. In  FIG.  6   , the frames  31 L and  31 R, the lower case  38 , and the exhaust guide  39  are not shown. 
     As shown in, for example,  FIGS.  4  and  5   , the pair of clamp brackets  24 L and  24 R are fixed to the back surface of the transom  14  with fasteners (not shown). A tilt shaft  20  is supported by the clamp bracket  24 L and the clamp bracket  24 R. The tilt shaft  20  extends in the left-and-right direction and is oriented horizontally or substantially horizontally. The tilt axis P 0  is the central axis of the tilt shaft  20 . The side swivel brackets  29 L and  29 R (coupling) and the swivel bracket  30  (a second coupling) are supported turnably about the tilt axis P 0  by the tilt shaft  20 . 
     As shown in  FIG.  6   , a front end portion  29 Lb, which is one end of the side swivel bracket  29 L, is supported by the tilt shaft  20 , and a front end portion  29 Rb, which is one end of the side swivel bracket  29 R, is supported by the tilt shaft  20 . Thus, the side swivel brackets  29 L and  29 R are turnable about the tilt axis P 0 . 
     A front end portion  30   b , which is one end of the swivel bracket  30 , is supported by the tilt shaft  20  in the region between the front end portion  29 Lb of the side swivel bracket  29 L and the front end portion  29 Rb of the side swivel bracket  29 R. Thus, the swivel bracket  30  is turnable about the tilt axis P 0  in the up-and-down direction relatively to the clamp brackets  24 L and  24 R. 
     In the direction of the tilt axis P 0  (left-and-right direction), the front end portion  29 Lb is located at the left end portion of the tilt shaft  20 , and the front end portion  29 Rb is located at the right end portion of the tilt shaft  20 . Thus, the position (first position) of the front end portion  29 Lb and the position (second position) of the front end portion  29 Rb are spaced apart from each other in the direction of the tilt axis P 0 . 
     As shown in, for example,  FIGS.  4  and  6   , a back end portion  29 La, which is the other end of the side swivel bracket  29 L, and a back end portion  29 Ra, which is the other end of the side swivel bracket  29 R, are both fixed to the lower mount  33  with a plurality of bolts, for example. In particular, in the left-and-right direction, the back end portion  29 La is fixed to a support position  33   a , which is a left end portion of the lower mount  33 , and the back end portion  29 Ra is fixed to a support position  33   b , which is a right end portion of the lower mount  33  ( FIG.  6   ). The back end portion  29 La and the back end portion  29 Ra are pivotally supported by a second pivot shaft  22 . The second pivot center P 2  is the central axis of the second pivot shaft  22 . The second pivot shaft  22  is located adjacent or near the lower mount  33 . 
     The PTT cylinder  25  changes a trim angle or a tilt angle of the outboard motor main body  101 . The PTT cylinder  25  extends from the back end portions  29 La and  29 Ra to the clamp brackets  24 L and  24 R. 
     As shown in  FIG.  3   , the rod  27  of PTT cylinder  25  includes a coupler  28 . The coupler  28  is pivotally supported by the second pivot shaft  22  between the back end portion  29 La and the back end portion  29 Ra in the left-and-right direction. This arrangement allows the side swivel brackets  29 L and  29 R and the PTT cylinder  25  to be relatively turnable with respect to each other about the second pivot center P 2 . The cylinder main body  26  of the PTT cylinder  25  is coupled to the clamp brackets  24 L and  24 R through a housing of the cylinder main body  26  and is turnable about the first pivot center P 1  ( FIGS.  4  and  5   ) of a first pivot shaft  21 . Thus, the clamp brackets  24 L and  24 R and the cylinder main body  26  are relatively turnable with respect to each other about the first pivot center P 1 . The first pivot center P 1  is lower in position than the tilt shaft  20 . 
       FIG.  7    is an enlarged side view of the periphery of the upper pivot  35 . A back end portion  30   a  (see also  FIGS.  4  and  6   ), which is the other end of the swivel bracket  30 , supports the upper pivot  35  turnably about the third pivot center P 3  (third pivot shaft) at least in the up-and-down direction. The upper pivot  35  is regulated in position in the Z direction by the exhaust guide  39  and a plate  37 . The upper pivot  35  includes a spherical portion  23 . The back end portion  30   a  of the swivel bracket  30  is slidably engaged with the spherical portion  23  through a bush (not shown). This arrangement allows the back end portion  30   a  of the swivel bracket  30  and the spherical portion  23  to be relatively turnable with respect to each other about the steering axis  41  and to be relatively turnable with respect to each other about the third pivot center P 3 . 
     A steering bracket  36  is engaged with a position in the −Z direction with respect to the spherical portion  23  in the upper pivot  35 , and a driver  42  is connected to the steering bracket  36  (see also  FIGS.  4  and  5   ). The frames  31 L and  31 R are fixed to the steering bracket  36 . The driver  42  causes the steering bracket  36  to turn about the steering axis  41 . As a result, the frames  31 L and  31 R turn about the steering axis  41 . The turning of the frames  31 L and  31 R allows the orientation of the outboard motor main body  101  in the left-and-right direction to be changed. 
     The side swivel brackets  29 L and  29 R are linear or substantially linear in shape in a side view ( FIGS.  4  and  5   ). Further, the side swivel bracket  29 L includes a portion that extends from the front end portion  29 Lb to the lower mount  33  and is linear or substantially linear in shape in a rear view, and the side swivel bracket  29 R includes a portion that extends from the front end portion  29 Rb to the lower mount  33  and is linear or substantially linear in shape in a rear view ( FIG.  6   ). 
     As shown in  FIG.  4   , with the outboard motor main body  101  in the tilt-down state, the third pivot center P 3  is lower in position than the tilt shaft  20 . That is, in the tilt-down state, the swivel bracket  30  inclines downward toward the rearward direction. Further, with the outboard motor main body  101  in the tilt-down state, the second pivot shaft  22  is lower in position than the first pivot shaft  21 . That is, in the tilt-down state, the PTT cylinder  25  inclines downward toward the rearward direction. 
     As shown in  FIG.  6   , the lower mount  33  is located between the front end portion  29 Lb and the front end portion  29 Rb in the direction parallel to the tilt axis P 0  (left-and-right direction). Further, in the tilt-down state, the lower mount  33  is lower in position than the front end portion  29 Lb and the front end portion  29 Rb. In the tilt-down state, an imaginary triangle  50  is defined by the front end portion  29 Lb, the front end portion  29 Rb, and the lower mount  33  as vertices, when viewed from the rear. The respective center positions of the front end portions  29 Lb and  29 Rb and the lower mount  33  as viewed from the rear define vertices Q 1 , Q 2 , and Q 3 , respectively. The vertices Q 1 , Q 2 , and Q 3  define the triangle  50 . 
     Meanwhile, as shown in  FIG.  4   , an imaginary triangle  40  defined by the tilt axis P 0  of the tilt shaft  20 , the first pivot center P 1  of the first pivot shaft  21 , and the second pivot center P 2  of the second pivot shaft  22  as vertices, in a side view. 
     Next, the operation of tilting up/down the outboard motor main body  101  by the PTT cylinder  25  will be described. The rod  27  extends and contracts with respect to the cylinder main body  26  due to a drive source (not shown). When the rod  27  extends, the coupler  28  ( FIG.  3   ) pushes the second pivot shaft  22 . Then, the side swivel brackets  29 L and  29 R receive a biasing force through the second pivot shaft  22 , and turn upward (counterclockwise direction in  FIG.  4   ), which is in the tilt-up direction about the tilt axis P 0 . Because the distance between the second pivot center P 2  and the third pivot center P 3  is constant, the swivel bracket  30  also turns in the tilt-up direction about the tilt axis P 0  in conjunction with the side swivel brackets  29 L and  29 R. 
     Conversely, when the rod  27  contracts from the state in which the rod  27  extends due to the tilting up, the side swivel brackets  29 L and  29 R and the swivel bracket  30  turn in the tilt down direction about the tilt axis P 0 . In the tilting up/down process, the shape of a triangle defined by the tilt axis P 0 , the second pivot center P 2 , and the third pivot center P 3  as vertices in a side view, is maintained. 
     A lateral load may be applied to the lower portion of the outboard motor main body  101  during navigation. For example, a leftward or rightward water pressure may be applied when the hull  11  turns. Further, a lateral load may be applied when the hull  11  leaves the surface of water and lands on water in a large swell. Furthermore, a forward thrust force due to thrust is applied to the suspension mechanism  200 . In the prior art, a large bending stress may act on the component members of the suspension mechanism due to a thrust force, the lateral load, or the own weight of the outboard motor main body. However, when the strength of the component members of the suspension mechanism is simply increased, its overall weight increases. Therefore, the present preferred embodiment reduces a bending stress acting on the component members of the suspension mechanism  200 . 
     As described above, the side swivel brackets  29 L and  29 R are linear or substantially linear in shape. As shown in  FIG.  6   , the lower mount  33  is located between the front end portion  29 Lb and the front end portion  29 Rb in the direction parallel to the tilt axis P 0 . In the tilt-down state, the lower mount  33  is lower in position than the front end portion  29 Lb and the front end portion  29 Rb, and the vertices Q 1 , Q 2 , and Q 3  define the triangle  50  when viewed from the rear. 
     Thus, if the lower mount  33  receives a thrust force from the right, a force (compressive force) that is able to compress a member acts on the side swivel bracket  29 L between the front end portion  29 Lb and the lower mount  33 , and a force (tensile force) that is able to extend a member acts on the side swivel bracket  29 R between the front end portion  29 Rb and the lower mount  33 . An action due to reception of a thrust force from the left is opposite to the above action. That is, with respect to a thrust force from the left-and-right direction, a compressive force acts on one of the side swivel brackets  29 L and  29 R, and a tensile force acts on the other of the side swivel brackets  29 L and  29 R. A bending stress hardly acts on the side swivel brackets  29 L and  29 R. Thus, an increase in the member strength of the side swivel brackets  29 L and  29 R to cope with the bending stress is significantly reduced. Therefore, the member strength of the suspension mechanism  200  is increased while significantly reducing or preventing an increase in the weight thereof. 
     Further, as shown in  FIG.  4   , the second pivot shaft  22  coupling the back end portion of the PTT cylinder  25  and the side swivel brackets  29 L and  29 R is located adjacent or near the lower mount  33 . In a side view, the imaginary triangle  40  defined by the tilt axis P 0 , the first pivot center P 1 , and the second pivot center P 2  as the vertices. Therefore, at least in the tilt-down state, due to the weight of the outboard motor main body  101  or a forward thrust force, a tensile force acts on the side swivel brackets  29 L and  29 R between the tilt shaft  20  and the second pivot shaft  22 , and a compressive force acts on the PTT cylinder  25  between the first pivot shaft  21  and the second pivot shaft  22 . As a result, a bending stress applied to the side swivel brackets  29 L and  29 R due to the weight of the outboard motor main body  101  or the forward thrust force is reduced. Thus, an increase in the member strength of the side swivel brackets  29 L and  29 R to cope with the bending stress is significantly reduced. Therefore, the strength of the suspension mechanism  200  is increased while significantly reducing or preventing an increase in the weight thereof. 
     Moreover, in the tilt-down state, the upper pivot  35  is higher in position than the lower mount  33 . Further, the front end portion  30   b  of the swivel bracket  30  is supported turnably by the tilt shaft  20 , and the back end portion  30   a  supports the upper pivot  35  turnably about the third pivot center P 3 . With this arrangement, the lower mount  33  as the main load receiver bears most of the weight of the outboard motor main body  101  or most of a forward thrust force. 
     In a state where the weight of the outboard motor main body  101  or a forward thrust force act, a force due to a rotational moment in the clockwise direction in  FIG.  4    about the second pivot center P 2  acts on the upper pivot  35 , whereas a load in the vertical direction or a forward load hardly acts. Thus, the lower mount  33  bears most of the weight of the outboard motor main body  101  or most of the forward thrust force. As a result, the effect of reducing a bending stress acting on the side swivel brackets  29 L and  29 R as described above is enhanced. Moreover, a tensile force is mainly generated in the swivel bracket  30  against the rotational moment about the second pivot center P 2 . Therefore, because application of a bending stress to the swivel bracket  30  is significantly reduced, the weight of the swivel bracket  30  is reduced and the strength of the swivel bracket  30  is improved. 
     According to a preferred embodiment of the present invention, among portions supporting the outboard motor main body  101 , the lower mount  33  is at the lowest in position, except for the clamp brackets  24 L and  24 R, when the outboard motor main body  101  is in the tilt-down state. The side swivel brackets  29 L and  29 R are supported turnably by the tilt shaft  20  at the front end portion  29 Lb (first position) and the front end portion  29 Rb (second position), and are fixed to the lower mount  33  at the back end portion  29 La and the back end portion  29 Ra. The lower mount  33  is located between the front end portion  29 Lb and the front end portion  29 Rb in the direction parallel to the tilt axis P 0 . In the tilt-down state, the lower mount  33  is lower in position than the front end portion  29 Lb and the front end portion  29 Rb. The imaginary triangle  50  defined by the front end portion  29 Lb, the front end portion  29 Rb, and the lower mount  33  as the vertices, when viewed from the rear ( FIG.  6   ). Therefore, because a bending stress applied to the side swivel brackets  29 L and  29 R due to a lateral load is reduced, the strength of the suspension mechanism  200  is increased while significantly reducing or preventing an increase in the weight thereof. 
     Further, the side swivel brackets  29 L and  29 R are linear or substantially linear in shape, and the front end portion  29 Lb and the front end portion  29 Rb are spaced apart in the direction of the tilt axis P 0 . With this arrangement, a bending stress is less likely to act on the side swivel brackets  29 L and  29 R. Furthermore, the lower mount  33  bears most of the weight of the outboard motor main body  101  or most of a forward thrust force. As a result, the effect of reducing a bending stress from acting on the side swivel brackets  29 L and  29 R is enhanced thus resulting in contributing to an increase in the strength of the side swivel brackets  29 L and  29 R and eventually the strength of the suspension mechanism  200 . 
     Further, according to a preferred embodiment of the present invention, at a position lower than the position of the tilt shaft  20 , the housing (one end) of the cylinder main body  26  of the PTT cylinder  25  is supported turnably about the first pivot shaft  21  (first pivot center P 1 ) in the up-and-down direction with respect to the clamp brackets  24 L and  24 R. Furthermore, the coupler  28  (the other end) of the rod  27  of the PTT cylinder  25  supports the side swivel brackets  29 L and  29 R turnably about the second pivot shaft  22  (second pivot center P 2 ) in the up-and-down direction. Still furthermore, the second pivot shaft  22  is located adjacent or near the lower mount  33 . With such a location, the imaginary triangle  40  is defined by the tilt axis P 0 , the first pivot center P 1 , and the second pivot center P 2  as the vertices, in a side view ( FIG.  4   ). Therefore, a bending stress applied to the side swivel brackets  29 L and  29 R due to the weight of the outboard motor main body  101  or a forward thrust force is reduced, and thus the strength of the suspension mechanism  200  is increased while significantly reducing or preventing an increase in the weight thereof. 
     Note that from the viewpoint of obtaining the above effects, the distance between the lower mount  33  and the second pivot shaft  22  in a side view is preferably shorter than that between the lower mount  33  and the tilt shaft  20  in the side view. Alternatively, from the viewpoint of obtaining these effects, the second pivot shaft  22  may be provided at the lower mount  33 . That is, in the side view, the second pivot shaft  22  (or the second pivot center P 2 ) may be superimposed on the lower mount  33 . 
     Further, because the lower mount  33  bears most of the weight of the outboard motor main body  101  or most of a forward thrust force, the effect of reducing a bending stress from acting on the side swivel brackets  29 L and  29 R is enhanced, thus resulting in contributing to an increase in the strength of the side swivel brackets  29 L and  29 R and eventually the strength of the suspension mechanism  200 . 
     Furthermore, in the tilt-down state, the third pivot center P 3  is lower in position than the tilt shaft  20 , and the swivel bracket  30  inclines downward toward the rearward direction ( FIG.  4   ). With this arrangement, in the tilt-down state, generation of an upward tensile stress in the clamp brackets  24 L and  24 R near the tilt shaft  20  is prevented. Therefore, the fixed state of the clamp brackets  24 L and  24 R to the transom  14  is firm. 
     Moreover, in the tilt-down state, the second pivot shaft  22  is lower in position than the first pivot shaft  21 , and the PTT cylinder  25  inclines downward toward the rearward direction ( FIG.  4   ). With this arrangement, in the tilt-down state, an upward stress acts on the clamp brackets  24 L and  24 R at the position of the first pivot shaft  21 . Therefore, in combination with this action and the fact that the swivel bracket  30  inclines downward toward the rearward direction, the distribution of stress applied to the clamp brackets  24 L and  24 R in the tilt-down state is optimized. As a result, the strength of the clamp brackets  24 L and  24 R is increased while significantly reducing or preventing an increase in the weight thereof. 
     Further, the mount holder  32  is preferably U-shaped or substantially U-shaped in a side view, and pinches the lower mount  33  in the direction of the steering axis  41  ( FIG.  4   ). With this arrangement, even if the mount holder  32  turns about the steering axis  41  at the time of steering, the mount holder  32  is able to firmly hold the lower mount  33  while avoiding interference with the lower mount  33 . 
     The shapes of the side swivel brackets  29 L and  29 R are not limited to the exemplified shapes, and thus may be, for example, shapes closer to a linear shape. 
     In a preferred embodiment of the present invention, the side swivel bracket is provided separately as the two components of the side swivel bracket  29 L as a first member and the side swivel bracket  29 R as a second member. These components, however, may be unitary as a single side swivel bracket. In such a case, the single side swivel bracket may be V-shaped or substantially V-shaped when viewed from the rear. 
     The marine vessel to which the suspension mechanism  200  of preferred embodiments of the present invention is applied is preferably any marine vessel to which an outboard motor is attachable, and thus the type is not limited. 
     The present invention has been described in detail based on the preferred embodiments described above. The present invention, however, is not limited to the specific preferred embodiments described above, and thus various changes can be made without departing from the gist of the present invention, and these changes are also included in the present invention. 
     While preferred embodiments of the present invention have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the present invention. The scope of the present invention, therefore, is to be determined solely by the following claims.