Note: Descriptions are shown in the official language in which they were submitted.
Attorney Docket No. 90606.1657/ai
OUTBOARD MOTOR
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of priority to
Japanese Patent Application No. 2018-092953 filed on May 14,
2018. The entire contents of this application are hereby
incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
[0002] The present invention relates to an outboard motor
that propels a vessel.
2. Description of the Related Art
[0003] US 7,311,571 Bl discloses a vessel propulsion
apparatus that includes an outboard motor. The vessel propulsion
apparatus includes a transom bracket that is to be attached to a
transom, a swivel bracket that is supported by the transom
bracket rotatably around a tilt axis, and a steering cylinder
that turns the outboard motor around a steering axis relative to
the swivel bracket. The front end portion of a cowl of the
outboard motor is disposed above the transom bracket. The
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steering cylinder is disposed between the transom bracket and
the cowl of the outboard motor.
[0004] The steering cylinder houses a piston member that
moves in a right-left direction. The piston member includes a
pivot support structure that supports a pivot member into which
a steering arm is inserted, and two end portions that are
disposed on the respective right and left of the pivot support
structure. The pivot member has a cylindrical shape extending in
an up-down direction and is turnable around the centerline of
the pivot member relative to the pivot support structure. The
steering arm has a cylindrical shape extending in a front-rear
direction and is inserted into a through-hole that penetrates
the pivot member in the front-rear direction.
[0005] When the steering cylinder moves the piston member in
the right-left direction, the pivot member is pushed by the
pivot support structure in the right-left direction, and the
steering arm turns around the steering axis while the pivot
member turns around the centerline of the pivot member. This
allows the outboard motor to turn around the steering axis
together with the steering arm, and the vessel to be steered.
[0006] When the outboard motor generates high thrust, the
outboard motor may slightly tilt forward or rearward relative to
the swivel bracket. In this case, a force to move the front end
of the steering arm upward or downward in a diagonally rearward
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direction is generated. The force is transmitted from the
steering arm to the pivot member, and presses a portion of the
pivot member against the pivot support structure at high
pressure. When the piston member moves in the right-left
direction under this condition, high frictional force is
generated between the pivot member and the pivot support
structure, thus decreasing the transmission efficiency of the
power transmitted from the steering cylinder to the outboard
motor.
SUMMARY OF THE INVENTION
[0007] In order to overcome the previously unrecognized and
unsolved challenges described above, preferred embodiments of
the present invention provide outboard motors that each prevent
a reduction in the transmission efficiency of the power to steer
an outboard motor main body. A preferred embodiment of the
present invention provides an outboard motor including a
steering shaft extending in an up-down direction, an outboard
motor main body that rotates around a centerline of the steering
shaft together with the steering shaft and that includes a prime
mover that generates power to rotate a propeller, a steering arm
that extends forward from the steering shaft and that turns
around the centerline of the steering shaft together with the
steering shaft, a steering actuator including a movable body
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that moves in a right-left direction, and a motion converter
that converts a movement of the movable body in the right-left
direction into a turning motion of the steering arm around the
centerline of the steering shaft, and that includes a bushing
holder into which the steering arm is inserted in a front-rear
direction and a bushing interposed between the steering arm and
the bushing holder and including an outer surface provided with
a pair of first sliding portions each including a convex arc-
shaped vertical section that is perpendicular or substantially
perpendicular to the right-left direction.
[0008] With the above structural arrangement, when the
steering actuator moves the movable body in the right-left
direction, the motion in the right-left direction is converted
into a turning motion of the steering arm by the motion
converter. The turning motion of the steering arm is transmitted
to the outboard motor main body through the steering shaft. This
causes the outboard motor main body to turn around the
centerline of the steering shaft, thus allowing the outboard
motor main body to be steered.
[0009] The steering arm extends forward from the steering
shaft and is inserted into the bushing holder in the front-rear
direction. The bushing is interposed between the steering arm
and the bushing holder. The bushing includes an outer surface
that includes a pair of first sliding portions. The bushing is
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retained in the bushing holder through at least the pair of
first sliding portions. The first sliding portions have a convex
arc-shaped vertical section that is perpendicular or
substantially perpendicular to the right-left direction. That
is, the vertical section of the first sliding portions defines
an arc shape.
[0010] When the prime mover of the outboard motor main body
rotates the propeller, a thrust to propel the hull forward or
rearward is generated. When a force moves the front end of the
steering arm upward or downward in a diagonally rearward
direction in accordance with the generation of the thrust, the
bushing turns relative to the bushing holder around a turning
axis that passes through the bushing and that extends in the
right-left direction while the pair of first sliding portions of
the outer surface of the bushing slide on the bushing holder.
This weakens a force that presses the bushing against the
bushing holder.
[0011] As described above, when the force that moves the
front end of the steering arm upward or downward in a diagonally
rearward direction is generated, the steering arm and the
bushing are intentionally moved relative to the bushing holder.
Thus, it is possible to prevent the bushing from being pressed
against the bushing holder at high pressure and to efficiently
transmit the power of the steering actuator to the outboard
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motor main body.
[0012] The prime mover may be an engine (internal combustion
engine) or an electric motor, or may be both an engine and an
electric motor. The steering actuator converts energy such as
electric power or hydraulic pressure into a linear motion of the
movable body in the right-left direction. The steering actuator
may be an electric actuator or a hydraulic actuator, or an
actuator other than these. The first sliding portions provided
on the outer surface of the bushing may have a spherical cap
shape or a strip shape having an arc-shaped cross section. That
is, the first sliding portions define a portion of a spherical
surface or a portion of a cylindrical surface.
[0013] In preferred embodiments of the present invention, at
least one of the following features may be added to the outboard
motor.
[0014] The outer surface of the bushing includes the pair of
first sliding portions each including the convex arc-shaped
vertical section that is perpendicular or substantially
perpendicular to the right-left direction and a pair of second
sliding portions each including a convex arc-shaped horizontal
section that is perpendicular or substantially perpendicular to
the up-down direction.
[0015] With the above structural arrangement, not only the
first sliding portions having a convex arc-shaped vertical
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section but also the second sliding portions having a convex
arc-shaped horizontal section are provided on the outer surface
of the bushing. While the movable body of the steering actuator
moves in the right-left direction, the steering arm turns around
the centerline of the steering shaft extending in the up-down
direction. Since the movement directions of the movable body and
the steering arm are different from each other, moving the
movable body in the right-left direction will generate a force
to turn the bushing around a vertical axis that passes through
the bushing.
[0016] The force causes the bushing to turn relative to the
bushing holder around the vertical axis while the pair of second
sliding portions of the outer surface of the bushing slide on
the bushing holder. This prevents the bushing from being pressed
against the bushing holder at high pressure. Furthermore, since
the first sliding portions and the second sliding portions are
provided on the bushing, the outboard motor is reduced in size
compared with a case in which the first sliding portions and the
second sliding portions are provided on respective separate
members.
[0017] Another preferred embodiment of the present invention
provides an outboard motor including a steering shaft extending
in an up-down direction, an outboard motor main body that
rotates around a centerline of the steering shaft together with
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the steering shaft and that includes a prime mover that
generates power to rotate a propeller, a steering arm that
extends forward from the steering shaft and that turns around
the centerline of the steering shaft together with the steering
shaft, a steering actuator including a movable body that moves
in a right-left direction, and a motion converter that converts
a movement of the movable body in the right-left direction into
a turning motion of the steering arm around the centerline of
the steering shaft, and that includes a bushing holder into
which the steering arm is inserted in a front-rear direction and
a bushing interposed between the steering arm and the bushing
holder and including an outer surface provided with a pair of
sliding portions each having a spherical cap-shape.
[0018] With the above structural arrangement, the steering
arm extends forward from the steering shaft and is inserted into
the bushing holder in the front-rear direction. The bushing is
interposed between the steering arm and the bushing holder. The
outer surface of the bushing includes a pair of sliding
portions. The bushing is retained in the bushing holder through
at least the pair of sliding portions. The sliding portions
define a rotating body that is obtained by rotating an arc
around a straight line that passes through the midpoint of the
arc and the center of the arc.
[0019] When the prime mover of the outboard motor main body
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rotates the propeller, a thrust to propel the hull forward or
rearward is generated. When a force moves the front end of the
steering arm upward or downward in a diagonally rearward
direction in accordance with the generation of the thrust, the
bushing turns relative to the bushing holder around the turning
axis that passes through the bushing and that extends in the
right-left direction while the pair of sliding portions of the
outer surface of the bushing slide on the bushing holder.
[0020] Furthermore, while the movable body of the steering
actuator moves in the right-left direction, the steering arm
turns around the centerline of the steering shaft extending in
the up-down direction. Thus, moving the movable body in the
right-left direction generates a force to turn the bushing
around the vertical axis that passes through the bushing. At
this time, the bushing turns relative to the bushing holder
around the vertical axis while the pair of sliding portions of
the outer surface of the bushing slide on the bushing holder.
[0021] As described above, when a force moves the front end
of the steering arm upward or downward in a diagonally rearward
direction in accordance with the generation of the thrust, the
bushing turns relative to the bushing holder. Likewise, when the
steering actuator moves the movable body in the right-left
direction, the bushing turns relative to the bushing holder.
That is, regardless of the direction of the torque applied to
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the bushing, the bushing turns relative to the bushing holder
and the torque is released. This prevents the bushing from being
pressed against the bushing holder at high pressure, thus
allowing the power of the steering actuator to be efficiently
transmitted to the outboard motor main body.
[0022] In the above preferred embodiments, at least one of
the following features may be added to the outboard motors.
[0023] The outboard motor main body is turnable around the
centerline of the steering shaft between a right maximum steered
position in which the outboard motor main body is steered to a
'rightmost position and a left maximum steered position in which
the outboard motor main body is steered to a leftmost position,
and a front end of the steering arm extends at least beyond a
midpoint of the bushing when the outboard motor main body is at
either of the right maximum steered position and the left
maximum steered position. The front end of the steering arm may
be located in front of the bushing when the outboard motor main
body is at either of the right maximum steered position and the
left maximum steered position.
[0024] With the above structural arrangement, when the
outboard motor main body is steered, the bushing moves along the
steering arm in a direction perpendicular or substantially
perpendicular to the centerline of the steering shaft. When the
outboard motor main body is located at the right maximum steered
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position or the left maximum steered position, the bushing is
the farthest from the centerline of the steering shaft, so that
the distance from the centerline of the steering shaft to the
bushing is the longest. As the outboard motor main body
approaches an original position at the midpoint between the
right maximum steered position and the left maximum steered
position, the bushing approaches the centerline of the steering
shaft.
[0025] The front end of the steering arm is located in front
of the bushing when the outboard motor main body is located at
either of the right maximum steered position and the left
maximum steered position. Thus, when the outboard motor main
body is located at any position within the range from the right
maximum steered position to the left maximum steered position,
the steering arm projects forward from the bushing, and the
front end of the steering arm is located in front of the
bushing.
[0026] In the case in which the front end of the steering arm
is located inside the bushing, when the outboard motor main body
is steered, the bushing moves along the steering arm, and the
length of a portion of the steering arm in contact with the
bushing varies. Thus, locating the front end of the steering arm
in front of the bushing at all times makes it possible to
stabilize the contact area between the steering arm and the
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bushing and minimize variations in pressure caused between the
steering arm and the bushing.
[0027] The bushing holder includes an inner circumferential
surface defining an arm-insertion hole into which the steering
arm is inserted, and a length of the arm-insertion hole in the
right-left direction increases at a rear end of the arm-
insertion hole.
[0028] With the above structural arrangement, the steering
arm is inserted into the arm-insertion hole of the bushing
holder. When the steering actuator moves the movable body in the
right-left direction, the angle of the steering arm with respect
to the arm-insertion hole changes. The width of the arm-
insertion hole, that is, the length of the arm-insertion hole in
the right-left direction increases at the rear end of the arm-
insertion hole. Thus, when the movable body moves in the right-
left direction, it is possible to prevent the steering arm from
coming into contact with the bushing holder.
[0029] The steering actuator further includes a support shaft
that penetrates the movable body in the right-left direction,
and the movable body includes a bearing surrounding the support
shaft and a housing surrounding the bearing, and the bearing
includes an outer race that rotates around a centerline of the
support shaft together with the housing, an inner race that
surrounds the support shaft inside the outer race, and a
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rotatable element that is disposed between the outer race and
the inner race, and the outboard motor further includes a
fastener that fixes the bushing holder to the housing.
[0030] With the above structural arrangement, the bushing
holder is fixed to the housing of the movable body by the
fastener. The housing is supported by the support shaft of the
steering actuator through the bearing. When the force that moves
the front end of the steering arm upward or downward is
transmitted to the housing through the bushing and the bushing
holder, the housing turns around the centerline of the support
shaft. Thus, the force is absorbed not only by the bushing
turning relative to the bushing holder but also by the housing
turning relative to the support shaft. It is thus possible to
absorb a greater force.
[0031] The bushing is disposed behind the movable body.
[0032] With the above structural arrangement, the bushing is
located behind the movable body and thus does not overlap the
movable body in a side view of the outboard motor. With the
conventional vessel propulsion apparatus described above, the
pivot member is located in the piston member. Thus, as compared
with the conventional vessel propulsion apparatus described
above, the structure of the movable body is simplified.
Furthermore, since the movable body is shortened in the right-
left direction as compared with the conventional vessel
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propulsion apparatus described above, it is possible to enlarge
the moving range of the movable body in the right-left
direction, and to increase the steered angle of the outboard
motor main body (the rotation angle around the centerline of the
steering shaft).
[0033] The bushing may be disposed below the movable body, or
may be disposed above the movable body.
[0034] The outboard motor further includes a clamp bracket
attachable to a rear surface of a hull, and a swivel bracket
rotatable around a tilt axis extending in the right-left
direction with respect to the clamp bracket, the swivel bracket
being rotatable together with the outboard motor main body and
the movable body, and the movable body overlaps the tilt axis in
a side view of the outboard motor.
[0035] With the above structural arrangement, when the
outboard motor main body turns upward or downward around the
tilt axis, the movable body also turns upward or downward around
the tilt axis. In a case in which the movable body overlaps the
tilt axis in a side view of the outboard motor, the volume of
the space through which the movable body passes when the movable
body turns around the tilt axis is smaller than in a case in
which there is no overlap. Thus, it is possible to reduce the
space in the hull in which a portion of the outboard motor main
body is disposed when the outboard motor main body tilts up.
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This makes it possible to effectively utilize the space within
the hull.
[0036] The outboard motor further includes a pair of clamp
brackets each provided with an inner side surface, an inner
circumferential surface that is open at the inner side surface,
and an attachment attachable to a rear surface of a hull, and
the pair of clamp brackets is spaced apart from each other in
the right-left direction, and a swivel bracket disposed between
the pair of clamp brackets and that is rotatable around a tilt
axis extending in the right-left direction with respect to the
pair of clamp brackets, and at least a portion of the movable
body is surrounded by the inner circumferential surface of the
clamp bracket in a side view of the outboard motor and the
movable body is movable to a plurality of positions including a
position above the swivel bracket and a position inside a space
surrounded by the inner circumferential surface of the clamp
bracket.
[0037] With the conventional vessel propulsion apparatus
described above, since the steering cylinder is disposed between
the transom bracket and the cowl of the outboard motor, it is
necessary to ensure a space, in which the steering cylinder is
disposed, between the transom bracket and the cowl of the
outboard motor. With the above structural arrangement, the
movable body is surrounded by the inner circumferential surface
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of the clamp bracket in a side view of the outboard motor. Thus,
it is not necessary to provide the space, in which the movable
body is disposed, between the clamp bracket and the cowl of the
outboard motor main body. Furthermore, since the movable body
moves into the inner circumferential surface of the clamp
bracket, the clamp bracket need not to be disposed laterally of
the moving range of the movable body. Thus, the pair of clamp
brackets are prevented from increasing in size in the right-left
direction.
[0038] When the outboard motor main body rotates in the
right-left direction around the centerline of the steering
shaft, the outboard motor main body approaches the right or left
clamp bracket. If the width between the pair of clamp brackets
in the right-left direction is large, the outboard motor main
body may come into contact with the clamp bracket. Therefore, in
order to prevent this, the clamp brackets need to be shortened
in the front-rear direction or reduced in size in the right-left
direction. With the above-described structural arrangement, the
width between the pair of clamp brackets is reduced, so that the
above measures are unnecessary.
[0039] The outboard motor further includes a support shaft
extending in an axial direction parallel or substantially
parallel to the tilt axis and that penetrates the clamp bracket
in the axial direction, and the movable body is movable in the
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axial direction of the support shaft along the support shaft.
[0040] With the above structural arrangement, the movable
body moves in the axial direction of the support shaft along the
support shaft. If the support shaft is long, the moving range of
the movable body is enlarged. If the moving range of the movable
body is large, a steered angle of the outboard motor main body
is increased. The support shaft is elongated so as to penetrate
through the clamp bracket. Therefore, the moving range of the
movable body is enlarged, and the steerable angle of the
outboard motor main body is increased.
[0041] The swivel bracket includes a tubular portion
surrounding the tilt axis and is inserted in the inner
circumferential surface of the clamp bracket, and the movable
body is movable to a position inside a space surrounded by both
of the inner circumferential surface of the clamp bracket and
the tubular portion of the swivel bracket.
[0042] With the above structural arrangement, the tubular
portion corresponding to a tilt shaft is provided on the swivel
bracket. The swivel bracket is rotatable around the tubular
portion with respect to the clamp brackets. The movable body is
movable to the inside of the tubular portion. In other words,
the tilt shaft to be inserted in the clamp bracket defines a
space inside which the movable body is disposed inside the clamp
bracket. Accordingly, the width between the pair of clamp
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brackets is reduced while the moving range of the movable body
is maintained.
[0043] 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
[0044] Fig. 1 is a schematic view showing the left side of an
outboard motor according to a preferred embodiment of the
present invention.
[0045] Fig. 2 is a schematic view showing a suspension device
included in the outboard motor when viewed from above.
[0046] Fig. 3 is a partial cross-sectional view showing the
suspension device and a steering device when viewed from above
with a top cover removed.
[0047] Fig. 4 is a side view showing an upper portion of the
suspension device when viewed from the left side with an end cap
removed.
[0048] Fig. 5 is a partial cross-sectional view showing a
cross section of the suspension device and the steering device
cut along a reference plane.
[0049] Fig. 6 is a rear left perspective view showing the
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steering device when viewed from diagonally above.
[0050] Fig. 7 is a cross-sectional view showing a vertical
section of a motion converter in a direction perpendicular or
substantially perpendicular to a right-left direction.
[0051] Fig. 8 is a cross-sectional view showing a horizontal
section of the motion converter.
[0052] Fig. 9 is a partial cross-sectional view showing the
suspension device when viewed from above with the top cover
removed, illustrating a steering tube moved leftward.
[0053] Fig. 10 is a partial cross-sectional view showing a
cross section of the suspension device and the steering device
taken along a reference plane, illustrating the steering device
when the outboard motor main body propels the hull forward.
[0054] Fig. 11 is a partial cross-sectional view showing a
cross section of the suspension device and the steering device
taken along a reference plane, illustrating the steering device
when the outboard motor main body propels the hull rearward.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0055] As described below, the outboard motor main body 2 is
turnable rightward or leftward around a steering axis As, and is
turnable upward or downward around a tilt axis At. The outboard
motor main body 2 in a reference posture will be hereinafter
described unless specific notice is given. The reference posture
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is a posture in which a rotation axis Ac of a crankshaft 7
extends in an up-down direction and a centerline Ap of a
propeller shaft 10 extends in a front-rear direction. The front-
rear direction, the up-down direction, and a right-left
direction are defined based on the outboard motor main body 2 in
the reference posture. A width direction corresponds to the
right-left direction. "Lateral" and "laterally" mean "outward in
the width direction."
[0056] Fig. 1 is a schematic view showing the left side of an
outboard motor 1 according to a preferred embodiment of the
present invention. Fig. 2 is a schematic view of a suspension
device 3 provided in the outboard motor 1 when viewed from
above.
[0057] Fig. 2 shows the outline of the outer surface of an
outboard motor main body 2 at the same height as the upper end
of a transom Ti by bold lines, alternate long and short dashed
lines, and chain double-dashed lines. The bold lines show the
outboard motor main body 2 when located at an intermediate
position between a right maximum steered position and a left
maximum steered position. The alternate long and short dashed
lines show the outboard motor main body 2 when located at the
right maximum steered position, and the chain double-dashed
lines show the outboard motor main body when located at the left
maximum steered position.
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[0058] As shown in Fig. 1, the outboard motor 1 includes the
outboard motor main body 2 that generates thrust to propel the
vessel, the suspension device 3 that attaches the outboard motor
main body 2 to a hull H1, a steering device 4 that turns the
outboard motor main body 2 rightward or leftward around a
steering axis As extending in an up-down direction, and a tilt
device 5 that turns the outboard motor main body 2 upward or
downward around a tilt axis At extending in a right-left
direction.
[0059] The outboard motor main body 2 includes an engine 6 as
an example of a prime mover that generates power to rotate a
propeller 11, and power transmissions 8 to 10 that transmit the
power of the engine 6 to the propeller 11. The outboard motor
main body 2 further includes an engine cowl 12 that houses the
engine 6, and casings 13 to 15 that house the power
transmissions 8 to 10. The casings 13 to 15 are disposed below
the engine cowl 12.
[0060] The engine 6 includes a crankshaft 7 that is rotatable
around a rotation axis Ac extending in the up-down direction.
The casings include an exhaust guide 13 in which the engine 6 is
located, an upper case 14 disposed under the exhaust guide 13,
and a lower case 15 disposed under the upper case 14. The power
transmissions include a drive shaft 8 extending in the up-down
direction inside the upper case 14 and the lower case 15, a
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propeller shaft 10 extending in a front-rear direction inside
the lower case 15, and a forward-reverse switching mechanism 9
to transmit the rotation from the drive shaft 8 to the propeller
shaft 10. The propeller 11 is attached to the rear end portion
of the propeller shaft 10 that projects rearward from the lower
case 15.
[0061] The engine 6 rotates the crankshaft 7 in a certain
rotational direction. The rotation of the crankshaft 7 is
transmitted to the propeller 11 through the drive shaft 8, the
forward-reverse switching mechanism 9, and the propeller shaft
10. This causes the propeller 11 to rotate around a centerline
Ap of the propeller shaft 10 together with the propeller shaft
10, thus generating thrust to propel the hull H1 forward or
rearward. The direction of the rotation transmitted from the
drive shaft 8 to the propeller shaft 10 is switched by the
forward-reverse switching mechanism 9. This allows the
rotational direction of the propeller 11 to be switched over
between the forward direction and the reverse direction that are
opposite to each other.
[0062] As shown in Fig. 2, the suspension device 3 includes a
pair of clamp brackets 16 attachable to a transom Ti provided on
a rear portion of the hull H1, a swivel bracket 19 supported by
the pair of clamp brackets 16 rotatably around the tilt axis At
extending in the right-left direction, and a steering shaft 23
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supported by the swivel bracket 19 rotatably around the steering
axis As extending in the up-down direction.
[0063] The pair of clamp brackets 16 are respectively
disposed on the right and left of the swivel bracket 19. The
clamp bracket 16 includes an attachment 17 to be attached to the
hull H1, and a swivel support 18 that supports the swivel
bracket 19. The attachment 17 is disposed at the rear of the
transom Ti. The swivel support 18 is disposed above the transom
Ti. A bolt Bl, for example, that fixes the clamp bracket 16 to
the hull H1 is inserted in a through hole 17h that penetrates
the attachment 17.
[0064] The swivel bracket 19 is disposed in front of the
outboard motor main body 2. The swivel bracket 19 includes a
housing 20 that houses the steering device 4, a pair of tubular
portions 21 supported by the swivel supports 18 of the clamp
brackets 16 and a tubular shaft support 22 that rotatably
supports the steering shaft 23, and a pair of tubular portions
21 supported by the swivel supports 18 of the clamp brackets 16.
The pair of tubular portions 22 are respectively disposed on the
right and left of the housing 20. The tubular portions 21
project laterally from the housing 20. The shaft support 22 is
disposed more rearward than the tubular portions 21. The
steering shaft 23 is inserted in the shaft support 22. The
centerline of the steering shaft 23 is located on the steering
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axis As.
[0065] The suspension device 3 includes a top cover 24
disposed over the swivel bracket 19, and a pair of end caps 25
disposed on the respective right and left of the pair of clamp
brackets 16. The steering device 4 is disposed between the top
cover 24 and the swivel bracket 19. Both end portions of the
steering device 4 (both end portions of a steering rod 32 to be
discussed later) are supported by the pair of respective end
caps 25. The pair of end caps 25 are fixed to the pair of
respective tubular portions 21 of the swivel bracket 19. Thus,
the steering device 4 is supported by the swivel bracket 19
through the pair of end caps 25.
[0066] As shown in Fig. 1, the suspension device 3 includes a
steering arm 26 that couples an upper end portion of the
steering shaft 23 to the steering device 4, an upper mount
bracket 27 that couples the upper end portion of the steering
shaft 23 to the outboard motor main body 2 through an upper
damper mount Ml, and a lower mount bracket 28 that couples a
lower end portion of the steering shaft 23 to the outboard motor
main body 2 through a lower damper mount M2.
[0067] The steering arm 26 is disposed above the swivel
bracket 19. The steering arm 26 extends forward from the
steering shaft 23. The steering arm 26 rotates around the
steering axis As together with the steering shaft 23. The front
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CA 3048282 2019-06-28
end portion of the steering arm 26 is disposed between the top
cover 24 and the swivel bracket 19. The steering arm 26 and the
upper mount bracket 27 preferably define an integral unitary
structure. The steering arm 26 may be an independent structure
from the upper mount bracket 27.
[0068] The upper mount bracket 27 and the lower mount bracket
28 are disposed above and below the swivel bracket 19,
respectively. The upper mount bracket 27 is joined by a bolt to
the upper damper mount Ml, while the lower mount bracket 28 is
joined by a bolt to the lower damper mount M2. The upper damper
mount M1 and the lower damper mount M2 are retained in the
outboard motor main body 2. The upper mount bracket 27 and the
lower mount bracket 28 are rotated around the steering axis As
together with the steering shaft 23.
[0069] Now, the suspension device 3 and the steering device 4
will be described below.
[0070] Fig. 3 is a partial cross-sectional view showing the
suspension device 3 and the steering device 4 when viewed from
above with the top cover 24 removed. Fig. 4 is a side view
showing the upper portion of the suspension device 3 when viewed
from the left side with the end caps 25 removed. Fig. 5 is a
partial cross-sectional view showing a cross section of the
suspension device 3 and the steering device 4 cut along a
reference plane NO. The reference plane NO corresponds to a
CA 3048282 2019-06-28
vertical plane which passes through the steering axis As and is
perpendicular or substantially perpendicular to the right-left
direction.
[0071] As shown in Fig. 3, the housing 20 of the swivel
bracket 19 includes a bottom wall 20b disposed between the pair
of clamp brackets 16, a front wall 20f extending upward from a
front edge of the bottom wall 20b, and two side walls 20s
respectively extending upward from a right edge and a left edge
of the bottom wall 20b. The top cover 24 (refer to Fig. 5) is
joined to the housing 20 by bolts, for example. The top cover 24
and the housing 20 define a housing chamber that houses the
steering device 4.
[0072] The pair of tubular portions 21 of the swivel bracket
19 project rightward or leftward from the sidewall 20s of the
housing 20. The inner circumferential surface 21i of the tubular
portion 21 is open on an inner side surface of the sidewall 20s.
As shown in Fig. 4, the inner circumferential surface 211 of the
tubular portion 21 is also open on an end surface of the tubular
portion 21. The tubular portion 21 surrounds the tilt axis At in
a side view. The tubular portion 21 includes an annular portion
21a that surrounds the tilt axis At in a side view, and a
plurality of projections 21p that project inward from the inner
circumferential surface of the annular portion 21a. The
plurality of projections 21p are disposed at positions aligned
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CA 3048282 2019-06-28
with a plurality of female screw holes 21h that are open on the
end surface of the tubular portion 21. A plurality of bolts B2,
for example (see Fig. 3), that fix the end caps 25 to the swivel
bracket 19, are bolted into the plurality of female screw holes
21h.
[0073] As shown in Fig. 3, the swivel support 18 of the clamp
bracket 16 supports the tubular portion 21 of the swivel bracket
19 through a sleeve bushing 29 that is interposed between the
tubular portion 21 and the swivel support 18. The swivel support
18 includes an inner circumferential surface 181 that surrounds
the tubular portion 21. The inner circumferential surface 18i of
the swivel support 18 is open on both an inner side surface 16i
and an outer side surface 16o of the clamp bracket 16. The
tubular portion 21 of the swivel bracket 19 penetrates the
swivel support 18 in the right-left direction and projects
laterally from the swivel support 18.
[0074] The end caps 25 are disposed laterally of the swivel
support 18 of the clamp bracket 16 and the tubular portion 21 of
the swivel bracket 19. The end caps 25 have an outer diameter
that is greater than the inner diameter of the swivel support 18
(the diameter of the inner circumferential surface 18i of the
swivel support 18). The opening provided on the end surface of
the tubular portion 21 is closed by the end cap 25. The end caps
25 are fixed to the tubular portion 21 by the plurality of bolts
27
CA 3048282 2019-06-28
B2.
[0075] The steering device 4 includes a steering actuator 31
to convert energy such as electric power or hydraulic pressure
into linear motion in the right-left direction, and a motion
converter 51 that converts the linear motion produced by the
steering actuator 31 into a turning motion of the steering arm
26. The steering actuator 31 includes the steering rod 32
extending in the right-left direction, and a steering tube 33
that reciprocates in the right-left direction along the steering
rod 32. The steering tube 33 is an example of a movable body
that moves in the right-left direction, while the steering rod
32 is an example of a support shaft that supports the movable
body.
[0076] Fig. 3 shows an example in which the steering actuator
31 is an electric actuator to convert electric power into linear
motion of the steering tube 33 in the right-left direction, and
reduction gears 40 included in the electric actuator include a
roller screw assembly. The steering actuator 31 may be an
actuator such as a hydraulic actuator other than the electric
actuator. The reduction gears 40 may be a device such as a ball
screw mechanism other than the roller screw assembly.
[0077] When the steering actuator 31 is an electric actuator,
the steering tube 33 includes an inner tube 43 to surround the
steering rod 32, and an electric motor 39 to rotate the inner
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tube 43. The steering tube 33 further includes the reduction
gears 40 that relatively move the inner tube 43 and the steering
rod 32 in the axial direction of the steering rod 32 as the
inner tube 43 or the steering rod 32 is rotated, and a housing
34 that houses the inner tube 43, the electric motor 39, and the
reduction gears 40. When the electric motor 39 rotates, the
housing 34 moves in the right-left direction relative to the
steering rod 32 together with the components accommodated in the
housing 34 such as the electric motor 39 and the reduction gears
40.
[0078] The steering rod 32 supports the steering tube 33. The
steering rod 32 penetrates the steering tube 33 in the right-
left direction. The steering rod 32 further penetrates the
swivel bracket 19 in the right-left direction. That is, the
steering rod 32 passes through the spaces surrounded by the
inner circumferential surfaces 21i of the two tubular portions
21 of the swivel bracket 19 and the space inside the housing 20
of the swivel bracket 19 in the right-left direction. Both end
portions of the steering rod 32 project laterally from the two
tubular portions 21 of the swivel bracket 19.
[0079] The steering rod 32 includes a large diameter portion
32L that penetrates the steering tube 33 in the right-left
direction, a small diameter portion 32s that projects laterally
from an end surface of the large diameter portion 32L, and a
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male screw portion 32m that projects laterally from an end
surface of the small diameter portion 32s. The large diameter
portion 32L, the small diameter portion 32s, and the male screw
portion 32m are coaxial with each other. The outer diameter of
the small diameter portion 32s is smaller than the outer
diameter of the large diameter portion 32L, while the outer
diameter of the male screw portion 32m is smaller than the outer
diameter of the small diameter portion 32s. The large diameter
portion 32L is longer in the right-left direction than any of
the small diameter portion 32s and the male screw portion 32m.
The large diameter portion 32L penetrates the swivel bracket 19
in the right-left direction.
[0080] Both
end portions of the steering rod 32 are supported
by the pair of respective end caps 25. The small diameter
portion 32s of the steering rod 32 is inserted into a through
hole that penetrates a central portion of the end cap 25 in the
right-left direction. The male screw portions 32m of the
steering rod 32 are disposed laterally of the end caps 25. The
male screw portion 32m is screwed onto a fixing nut Ni. The end
cap 25 is sandwiched in the right-left direction between the
inner side surface of the fixing nut Ni and the end surface of
the large diameter portion 32L. This allows the end caps 25 to
be fixed to the steering rod 32. Thus, the steering rod 32 is
fixed to the swivel bracket 19 through the end caps 25.
CA 3048282 2019-06-28
[0081] The housing 34 includes a tubular main tube 35 that
surrounds the steering rod 32, and a center box 36 that projects
upward, forward, and rearward from a central portion of the main
tube 35 in the right-left direction. The housing 34 further
includes an upper cover 37 disposed above the center box 36, two
ring-shaped end plates 38 disposed on both respective ends of
the main tube 35, and two seal rings Si that seal the space
between the two end plates 38 and the steering rod 32 (see Fig.
4).
[0082] As shown in Fig. 4, the main tube 35 is surrounded in
a side view by the inner circumferential surfaces 21i of the
tubular portions 21 of the swivel bracket 19. The main tube 35
does not overlap any portion of the tubular portions 21 in a
side view. The main tube 35 and the steering rod 32 each have a
centerline located on the tilt axis At. The end plate 38 is
surrounded by the main tube 35. The outer circumferential
surface of the end plates 38 is in contact with the main tube
35, while the inner circumferential surface of the end plates 38
surrounds the steering rod 32. The two seal rings Si are
supported by the two respective end plates 38.
[0083] As shown in Fig. 3, the center box 36 is shorter than
the main tube 35 in the right-left direction. The upper cover 37
is attached to an upper end portion of the center box 36. The
upper end portion of the center box 36 defines an opening that
31
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is open upward. The opening of the center box 36 is covered with
the upper cover 37. The rear surface of the center box 36
defines a recess 36r that is recessed forward. Fig. 3 shows the
steering device 4 when the outboard motor main body 2 is
disposed at the original position. When the outboard motor main
body 2 is disposed at the original position, a front end 26f of
the steering arm 26 is disposed inside the recess 36r of the
center box 36.
[0084] The steering tube 33 is disposed in the housing 20 of
the swivel bracket 19. The front wall 20f of the housing 20 is
disposed in front of the steering tube 33, and the bottom wall
20b of the housing 20 is disposed below the steering tube 33.
When the outboard motor main body 2 is disposed at the original
position, the two sidewalls 20s of the housing 20 are disposed
on the respective right and left of the main tube 35. As
described below, when the steering actuator 31 moves the
steering tube 33 in the right-left direction, the main tube 35
is brought into a space surrounded by both the swivel support 18
of the clamp bracket 16 and the tubular portion 21 of the swivel
bracket 19.
[0085] The housing 34 accommodates the electric motor 39 and
the reduction gears 40. The electric motor 39 includes a rotor
39r that surrounds the reduction gears 40, and a stator 39s that
surrounds the rotor 39r. The reduction gears 40 include a center
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CA 3048282 2019-06-28
shaft 41 extending in the right-left direction, and a plurality
of cylindrical rollers 42 that are disposed around the center
shaft 41. The inner tube 43 surrounds the plurality of
cylindrical rollers 42.
[0086] The center shaft 41 has a centerline located on the
tilt axis At. The center shaft 41 may be integral with the
steering rod 32 or may be a member which is separate from the
steering rod 32 and fixed to the steering rod 32. A helical
screw thread provided on the outer circumferential surface of
each cylindrical roller 42 engages with a helical screw thread
provided on the outer circumferential surface of the center
shaft 41 and the spiral-shaped screw thread provided on the
inner circumferential surface of the inner tube 43.
[0087] The rotation of the center shaft 41 is converted into
a linear motion of the inner tube 43 through the center shaft
41, the cylindrical roller 42, and the inner tube 43. Likewise,
the rotation of the inner tube 43 is converted into a linear
motion of the center shaft 41 through the center shaft 41, the
cylindrical roller 42, and the inner tube 43. When one of the
center shaft 41 and the inner tube 43 is rotated, the other of
the center shaft 41 and the inner tube 43 linearly moves, and
thus the center shaft 41 and the inner tube 43 relatively move
in the axial direction of the center shaft 41 (in the right-left
direction).
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[0088] The steering tube 33 includes a pair of bearings 44
interposed between the housing 34 and the inner tube 43. Each
bearing 44 includes an inner race 44i surrounding the steering
rod 32, an outer race 44o surrounding the inner race 44i, and a
plurality of rotatable elements 44r disposed between the inner
race 44i and the outer race 44o. The inner race 44i of the
bearing 44 and the rotor 39r of the electric motor 39 rotate
around the centerline of the steering rod 32 together with the
inner tube 43. The outer race 440 of the bearing 44 and the
stator 39s of the electric motor 39 rotate together with the
housing 34.
[0089] When the electric motor 39 rotates the inner tube 43,
the torque transmitted from the electric motor 39 to the inner
tube 43 is converted into the drive power that linearly moves
the inner tube 43 in the right-left direction through the center
shaft 41, the cylindrical roller 42, and the inner tube 43. The
drive power causes the steering tube 33 to move in the right or
left direction relative to the steering rod 32. The amount of
movement and the direction of movement of the steering tube 33
are controlled by the amount and the direction of rotation of
the electric motor 39.
[0090] Now, the motion converter 51 and a steering angle
detector 61 of the steering device 4 will be described below.
[0091] Fig. 6 is a rear left perspective view showing the
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CA 3048282 2019-06-28
steering device 4 when viewed from diagonally above. Fig. 7 is a
cross-sectional view showing a vertical section of the motion
converter 51 in a direction perpendicular or substantially
perpendicular to the right-left direction. Fig. 8 is a cross-
sectional view showing a horizontal section of the motion
converter 51.
[0092] As shown in Fig. 6, the motion converter 51 includes a
sphere-shaped bushing 52 attached to the front end portion of
the steering arm 26, and a bushing holder 53 that holds the
bushing 52. As shown in Fig. 7, the bushing holder 53 includes a
main holder 54 into which the steering arm 26 is inserted, and
an inner holder 55 that holds the bushing 52 together with the
main holder 54.
[0093] The bushing 52, the main holder 54, and the inner
holder 55 are disposed behind the center box 36 of the housing
34. The main holder 54 is fixed to the center box 36 by bolts
B3, for example, which are an example of a fastener (see Fig.
6). The inner holder 55 is disposed inside the main holder 54.
The inner holder 55 is fixed to the main holder 54 by bolts, for
example. The main holder 54 and the inner holder 55 move in the
right-left direction together with the steering tube 33 relative
to the steering rod 32.
[0094] The main holder 54 includes a hemisphere-shaped lower
support surface 54s disposed below the bushing 52. The inner
CA 3048282 2019-06-28
holder 55 includes a hemisphere-shaped upper support surface 55s
disposed above the bushing 52. Each of the upper support surface
55s and the lower support surface 54s has a radius of curvature
that is equal or substantially equal to the radius of curvature
of a sphere-shaped outer surface 52o of the bushing 52. The
bushing 52 is sandwiched between the upper support surface 55s
and the lower support surface 54s in the up-down direction. The
bushing 52 is turnable relative to the bushing holder 53 around
any axis that passes through the bushing 52.
[0095] The outer surface 52o of the bushing 52 includes a
plurality of sliding portions 52s that are in contact with the
upper support surface 55s and the lower support surface 54s. The
center of the bushing 52 defines a midpoint of the bushing 52.
As long as the sliding portion 52s is cut by a plane passing
through the center of the bushing 52, a convex arc-shaped cross
section appears when the sliding portion 52s is cut by any
plane. For example, as shown in Fig. 7, when the sliding portion
52s is cut by a vertical plane that passes through the center of
the bushing 52 and is perpendicular or substantially
perpendicular to the right-left direction, an arc-shaped cross
section convex in the upward or downward direction appears. As
shown in Fig. 8, when the sliding portion 52s is cut by a
horizontal plane that passes through the center of the bushing
52, an arc-shaped cross section convex in the right or left
36
CA 3048282 2019-06-28
direction appears.
[0096] The front end portion of the steering arm 26 is
inserted into an arm-insertion hole 54h that extends forward
from the rear surface of the main holder 54. The bushing 52 is
located in front of the arm-insertion hole 54h. The front end
portion of the steering arm 26 is inserted into an insertion
hole 52h extending forward from the outer surface 52o of the
bushing 52. Thus, the front end portion of the steering arm 26
is inserted into both the arm-insertion hole 54h and the
insertion hole 52h.
[0097] The arm-insertion hole 54h of the main holder 54 is
open on the rear surface of the main holder 54. The arm-
insertion hole 54h extends forward from the rear surface of the
main holder 54 to the bushing 52. As shown in Fig. 8, the arm-
insertion hole 54h has a width (a length in the right-left
direction) that decreases toward the bushing 52. The width of
the arm-insertion hole 54h on the rear surface of the main
holder 54 is greater than the maximum outer diameter of the
bushing 52. As shown in Fig. 7, the height (the length in the
up-down direction) of the arm-insertion hole 54h on the rear
surface of the main holder 54 is smaller than the maximum outer
diameter of the bushing 52. The arm-insertion hole 54h may not
have an entirely closed circumference but may be a notch.
[0098] The insertion hole 52h of the bushing 52 is defined by
37
CA 3048282 2019-06-28
an inner circumferential surface 52i of the bushing 52. The
inner circumferential surface 52i of the bushing 52 has a
circular vertical section that is perpendicular or substantially
perpendicular to the front-rear direction. The bushing 52 has an
inner diameter (the diameter of the inner circumferential
surface 52i of the bushing 52) that is constant from the front
end of the insertion hole 52h to the rear end of the insertion
hole 52h. As long as the insertion hole 52h has a uniform
sectional shape from the front end of the insertion hole 52h to
the rear end of the insertion hole 52h, the vertical section of
the inner circumferential surface 52i of the bushing 52 may have
any shape such as a polygonal shape other than a circular shape.
[0099] The inner circumferential surface 52i of the bushing
52 surrounds an outer circumferential surface 26o of the
steering arm 26. The outer circumferential surface 26o of the
steering arm 26 has the same sectional shape as that of the
inner circumferential surface 52i of the bushing 52. Fig. 7 and
Fig. 8 show an example in which the cross-sectional shape of the
outer circumferential surface 26o of the steering arm 26 is
circular. The outer diameter of the outer circumferential
surface 26o of the steering arm 26 is constant from the front
end of the outer circumferential surface 26o of the steering arm
26 (which corresponds to the front end 26f of the steering arm
26) to a rear end 26r of the outer circumferential surface 26o
38
CA 3048282 2019-06-28
of the steering arm 26 (see Fig. 8). The bushing 52 is movable
relative to the steering arm 26 along the outer circumferential
surface 26o of the steering arm 26 in a direction perpendicular
or substantially perpendicular to the steering axis As (see Fig.
6).
[0100] As shown in Fig. 7 and Fig. 8, the steering arm 26 is
inserted into the insertion hole 52h from behind the bushing 52.
The steering arm 26 penetrates the bushing 52 in the front-rear
direction and projects forward from the bushing 52. The front
end 26f of the steering arm 26 is located behind the center box
36 of the housing 34 and spaced apart from the center box 36.
[0101] As described below, when the outboard motor main body
2 is steered from the original position, the bushing 52 moves
along the steering arm 26 toward the front end 26f of the
steering arm 26. Even when the outboard motor main body 2 is
located at the right maximum steered position or the left
maximum steered position, the steering arm 26 penetrates the
bushing 52, and the front end 26f of the steering arm 26 is
located outside the bushing 52. Thus, the front end 26f of the
steering arm 26 is located outside the bushing 52 when the
outboard motor main body 2 is located at any position around the
steering axis As.
[0102] As shown in Fig. 7, the steering device 4 includes the
steering angle detector 61 that detects the steered angle of the
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CA 3048282 2019-06-28
outboard motor main body 2. Fig. 7 shows an example in which the
steering angle detector 61 detects the rotation angle of the
bushing 52. In the example, the steering angle detector 61
includes a magnet 63 that rotates together with the bushing 52,
a steering angle sensor 62 that detects the rotation angle of
the magnet 63, and a magnet holder 64 that holds the magnet 63
and transmits the rotation of the bushing 52 to the magnet 63.
The steering angle detector 61 may detect the amount of movement
of any movable portion such as the steering arm 26 other than
the bushing 52.
[0103] The steering angle sensor 62 is disposed above the
magnet 63. The steering angle sensor 62 is separated from the
magnet 63. The steering angle sensor 62 is retained in the
housing 34. The magnet 63 is movable relative to the steering
angle sensor 62 around a turning axis Al that is parallel or
substantially parallel to the steering axis As and passes
through the bushing 52. The magnet 63 is located above the
magnet holder 64 and the inner holder 55.
[0104] The magnet holder 64 includes a cup 64c into which the
magnet 63 is inserted, a base 64b in contact with the bushing
52, and a cylindrical shaft 64s extending from the base 64b to
the cup 64c. The magnet 63 and the cup 64c are located above the
inner holder 55. The base 64b is located below the inner holder
55. The shaft 64s is inserted into a through hole 55h extending
CA 3048282 2019-06-28
upward from the upper support surface 55s of the inner holder
55. The magnet 63 and the magnet holder 64 are rotatable around
the shaft 64s relative to the inner holder 55.
[0105] The base 64b of the magnet holder 64 is inserted into
a fitting groove 52g that is recessed from the outer surface 52o
of the bushing 52 toward the center of the bushing 52. As shown
in Fig. 8, in a plan view, the fitting groove 52g of the bushing
52 has a strip shape extending in the front-rear direction.
Likewise, the base 64b has a strip shape extending in the front-
rear direction in a plan view. As shown in Fig. 7, the fitting
groove 52g of the bushing 52 includes an arc-shaped bottom
surface that is concentric with the outer surface 52o of the
bushing 52. The base 64b includes an arc-shaped lower surface
having a radius of curvature that is equal or substantially
equal to that of the bottom surface of the fitting groove 52g.
The base 64b is shorter than the fitting groove 52g in the
front-rear direction. The base 64b is movable relative to the
fitting groove 52g along the bottom surface of the fitting
groove 52g in the front-rear direction.
[0106] When a force to turn the bushing 52 around the turning
axis Al is generated, the right and left side surfaces of the
base 64b are pushed by the right and left side surfaces of the
fitting groove 52g, so that the magnet holder 64 turns relative
to the bushing holder 53 together with the bushing 52. This
41
CA 3048282 2019-06-28
causes the steering angle sensor 62 and the magnet 63 to
relatively move around the turning axis Al, thus detecting the
rotation angle of the magnet 63. The steered angle of the
outboard motor main body 2 is measured based on a value detected
by the steering angle sensor 62.
[0107] Now, description will be made for the operation of the
steering device 4 when the outboard motor main body 2 is
steered.
[0108] Fig. 9 is a partially cross-sectional view of the
suspension device 3 with the top cover 24 removed when viewed
from above, showing the steering tube 33 moved to the left.
[0109] When the steering actuator 31 generates a right
steering force to move the steering tube 33 in the left
direction, the right steering force is transmitted to the
steering arm 26 through the housing 34, the bushing holder 53,
and the bushing 52. This causes the steering arm 26 to be pushed
leftward, so that the steering arm 26 and the steering shaft 23
turn leftward around the steering axis As. This causes the
outboard motor main body 2 to turn rightward around the steering
axis As.
[0110] As understood by comparing Fig. 3 with Fig. 9, when
the steering actuator 31 generates the right steering force, the
steering arm 26 and the bushing 52 turn relative to the bushing
holder 53 around the turning axis Al that is parallel or
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substantially parallel to the steering axis As and that passes
through the bushing 52 while the outer surface 52o of the
bushing 52 slides on the bushing holder 53. Furthermore, the
bushing 52 moves in a direction perpendicular or substantially
perpendicular to the steering axis As along the outer
circumferential surface 26o of the steering arm 26.
[0111] Likewise, when the steering actuator 31 generates a
left steering force to move the steering tube 33 in the right
direction, the left steering force is transmitted to the
steering arm 26 through the housing 34, the bushing holder 53,
and the bushing 52. This causes the steering arm 26 to be pushed
rightward, so that the steering arm 26 and the steering shaft 23
turn rightward around the steering axis As. This also causes the
outboard motor main body 2 to turn leftward around the steering
axis As.
[0112] When the steering actuator 31 generates the left
steering force, the steering arm 26 and the bushing 52 turn
relative to the bushing holder 53 around the turning axis Al
that is parallel to the steering axis As and that passes through
the bushing 52 while the outer surface 52o of the bushing 52
slides on the bushing holder 53. Furthermore, the bushing 52
moves along the outer circumferential surface 26o of the
steering arm 26 in a direction perpendicular or substantially
perpendicular to the steering axis As.
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[0113] Fig. 9 shows the steering device 4 when the outboard
motor main body 2 is located at the right maximum steered
position. When the outboard motor main body 2 is located at the
right maximum steered position, the left end portion of the
steering tube 33 is located in a space surrounded by both the
swivel support 18 of the left clamp bracket 16 and the left
tubular portion 21 of the swivel bracket 19. At this time, the
front end 26f of the steering arm 26 is located outside the
bushing 52. Furthermore, the steering arm 26 is not in contact
with but separated from the inner circumferential surface 54i of
the arm-insertion hole 54h of the bushing holder 53.
[0114] Moving the steering tube 33 in the right direction
will cause the outboard motor main body 2 to turn leftward
around the steering axis As. The left maximum steered position
and the right maximum steered position are symmetric to each
other with respect to the reference plane WO. When the outboard
motor main body 2 is located at the left maximum steered
position, the right end portion of the steering tube 33 is
located in a space that is surrounded by both the swivel support
18 of the right clamp bracket 16 and the right tubular portion
21 of the swivel bracket 19. At this time, the front end 26f of
the steering arm 26 is located outside the bushing 52.
Furthermore, the steering arm 26 is not in contact with but
separated from the inner circumferential surface 541 of the arm-
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insertion hole 54h of the bushing holder 53.
[0115] Now, description will be made for the operation of the
steering device 4 when a tilting force to tilt the outboard
motor main body 2 forward or rearward is generated in accordance
with the generation of the thrust.
[0116] Fig. 10 and Fig. 11 are partial cross-sectional views
showing cross sections of the suspension device 3 and the
steering device 4 taken along the reference plane WO. Fig. 10
shows the steering device 4 when the outboard motor main body 2
propels the hull H1 forward. Fig. 11 shows the steering device 4
when the outboard motor main body 2 propels the hull H1
rearward.
[0117] A high thrust to propel the hull H1 (see Fig. 1)
forward will generate a tilting force that tilts the outboard
motor main body 2 (see Fig. 1) rearward, that is, a force that
causes the upper portion of the outboard motor main body 2 to
move rearward relative to the hull H1 and the lower portion of
the outboard motor main body 2 to move forward relative to the
hull Hl. In contrast, a high thrust to propel the hull H1
rearward will generate a tilting force that tilts the outboard
motor main body 2 rearward, that is, a force that causes the
upper portion of the outboard motor main body 2 to move forward
relative to the hull H1 and the lower portion of the outboard
motor main body 2 to move rearward relative to the hull Hl.
CA 3048282 2019-06-28
[0118] The tilting force that tilts the outboard motor main
body 2 forward or rearward is transmitted to the steering shaft
23 through the outboard motor main body 2. The steering shaft 23
is inserted into the shaft support 22 of the swivel bracket 19
and supported by the shaft support 22 through a sleeve bushing
65 surrounding the steering shaft 23. When the tilting force is
transmitted to the steering shaft 23, the steering shaft 23 is
tilted forward or rearward relative to the shaft support 22
within the range of a slight gap between the inner
circumferential surface of the sleeve bushing 65 and the outer
circumferential surface of the steering shaft 23. At this time,
the front end 26f of the steering arm 26 moves slightly upward
or downward relative to the swivel bracket 19.
[0119] As shown in Fig. 10, a high thrust to propel the hull
H1 forward will generate a force to move the front end 26f of
the steering arm 26 upward relative to the swivel bracket 19.
This causes the steering arm 26 to push the bushing 52 upward
and the bushing 52 to push the bushing holder 53 upward. At this
time, while the outer surface 52o of the bushing 52 slides on
the bushing holder 53, the steering arm 26 and the bushing 52
turn relative to the bushing holder 53 around a turning axis A2
that passes through the bushing 52 and that extends in the
right-left direction.
[0120] Furthermore, the force to move the front end 26f of
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the steering arm 26 upward relative to the swivel bracket 19 is
transmitted to the housing 34 through the bushing 52 and the
bushing holder 53. Thus, the bushing holder 53 and the housing
34 turn upward around the tilt axis At. These operations cause
the front end 26f of the steering arm 26 to move upward relative
to the swivel bracket 19. Thus, the force of the steering arm 26
to push the bushing 52 upward is reduced, and the force of the
bushing 52 to push the bushing holder 53 upward is reduced.
[0121] As shown in Fig. 11, a high thrust to propel the hull
H1 rearward will generate a force to move the front end 26f of
the steering arm 26 downward relative to the swivel bracket 19.
This causes the steering arm 26 to push the bushing 52 downward
and the bushing 52 to push the bushing holder 53 downward. At
this time, while the outer surface 52o of the bushing 52 slides
on the bushing holder 53, the steering arm 26 and the bushing 52
turn relative to the bushing holder 53 around the turning axis
A2 that passes through the bushing 52 and that extends in the
right-left direction.
[0122] Furthermore, the force to move the front end 26f of
the steering arm 26 downward relative to the swivel bracket 19
is transmitted to the housing 34 through the bushing 52 and the
bushing holder 53. Thus, the bushing holder 53 and the housing
34 turn downward around the tilt axis At. These operations cause
the front end 26f of the steering arm 26 to move downward
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relative to the swivel bracket 19. Thus, the force of the
steering arm 26 to push the bushing 52 downward is reduced, and
the force of the bushing 52 to push the bushing holder 53
downward is reduced.
[0123] As described above, even when the outboard motor main
body 2 generates a high thrust, and the steering shaft 23 tilts
forward or rearward relative to the swivel bracket 19, the
steering arm 26 is prevented from being pressed against the
bushing 52 at high pressure, while the bushing 52 is prevented
from being pressed against the bushing holder 53 at high
pressure. Thus, when the outboard motor main body 2 is steered
while the outboard motor main body 2 generates a high thrust, a
high friction is not applied to the steering arm 26, the bushing
52, and the bushing holder 53. This enables the steering force
to be efficiently transmitted from the steering device 4 to the
outboard motor main body 2.
[0124] As described above, in the present preferred
embodiment, the steering arm 26 extends forward from the
steering shaft 23, and is inserted into the bushing holder 53 in
the front-rear direction. The bushing 52 is interposed between
the steering arm 26 and the bushing holder 53. The outer surface
52o of the bushing 52 includes the pair of sliding portions 52s.
The bushing 52 is retained in the bushing holder 53 through at
least the pair of sliding portions 52s. The sliding portion 52s
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,
includes a rotating body that is obtained by rotating an arc
around a straight line that passes through the midpoint of the
arc and the center of the arc.
[0125] When the engine 6 of the outboard motor main body 2
rotates the propeller 11, a thrust to propel the hull H1 forward
or rearward is generated. When a force to move the front end 26f
of the steering arm 26 upward or downward in a diagonally
rearward direction is generated in accordance with the
generation of the thrust, the bushing 52 turns relative to the
bushing holder 53 around the turning axis A2 that passes through
the bushing 52 and that extends in the right-left direction
while the pair of sliding portions 52s of the outer surface 52o
of the bushing 52 slide on the bushing holder 53.
[0126] Furthermore, the steering tube 33 of the steering
actuator 31 moves in the right-left direction, whereas the
steering arm 26 turns around the centerline of the steering
shaft 23 extending in the up-down direction. Thus, moving the
steering tube 33 in the right-left direction generates a force
to turn the bushing 52 around the turning axis Al that passes
through the bushing 52 and that extends in the up-down
direction. At this time, while the pair of sliding portions 52s
of the outer surface 52o of the bushing 52 slide on the bushing
holder 53, the bushing 52 turns around the vertical axis
relative to the bushing holder 53.
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[0127] As described above, when a force to move the front end
26f of the steering arm 26 upward or downward in a diagonally
rearward direction is generated in accordance with the
generation of the thrust, the bushing 52 turns relative to the
bushing holder 53. Likewise, when the steering actuator 31 moves
the steering tube 33 in the right-left direction, the bushing 52
turns relative to the bushing holder 53. That is, regardless of
the direction of the torque applied to the bushing 52, the
bushing 52 turns relative to the bushing holder 53 and the
torque is released. This prevents the bushing 52 from being
pressed against the bushing holder 53 at high pressure, thus
efficiently transmitting the power of the steering actuator 31
to the outboard motor main body 2.
[0128] In the present preferred embodiment, when the outboard
motor main body 2 is steered, the bushing 52 moves along the
steering arm 26 in a direction perpendicular or substantially
perpendicular to the centerline of the steering shaft 23. When
the outboard motor main body 2 is located at the right maximum
steered position or the left maximum steered position, the
bushing 52 is the farthest from the centerline of the steering
shaft 23, so that the distance from the centerline of the
steering shaft 23 to the bushing 52 is the longest. As the
outboard motor main body 2 approaches an original position at
the midpoint between the right maximum steered position and the
CA 3048282 2019-06-28
left maximum steered position, the bushing 52 comes closer to
the centerline of the steering shaft 23.
[0129] The front end 26f of the steering arm 26 is located in
front of the bushing 52 when the outboard motor main body 2 is
located at either of the right maximum steered position or the
left maximum steered position. Thus, when the outboard motor
main body 2 is located at any position within the range from the
right maximum steered position to the left maximum steered
position, the steering arm 26 projects forward from the bushing
52, and the front end 26f of the steering arm 26 is located in
front of the bushing 52.
[0130] In a case in which the front end 26f of the steering
arm 26 is located inside the bushing 52, when the outboard motor
main body 2 is steered, the bushing 52 moves along the steering
arm 26, and the length of a portion of the steering arm 26 in
contact with the bushing 52 varies. Thus, locating the front end
26f of the steering arm 26 in front of the bushing 52 at all
times makes it possible to stabilize the contact area between
the steering arm 26 and the bushing 52 and minimize variations
in pressure caused between the steering arm 26 and the bushing
52.
[0131] In the present preferred embodiment, the steering arm
26 is inserted into the arm-insertion hole 54h of the bushing
holder 53. When the steering actuator 31 moves the steering tube
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33 in the right-left direction, the angle of the steering arm 26
with respect to the arm-insertion hole 54h changes. The width of
the arm-insertion hole 54h, that is, the length of the arm-
insertion hole 54h in the right-left direction increases at the
rear end of the arm-insertion hole 54h. Thus, when the steering
tube 33 moves in the right-left direction, it is possible to
prevent the steering arm 26 from coming into contact with the
bushing holder 53.
[0132] In the present preferred embodiment, the bushing
holder 53 is fixed to the housing 34 of the steering tube 33
using the bolts E3, which are an example of a fastener. The
housing 34 is supported by the steering rod 32 of the steering
actuator 31 through the bearings 44. When the force to move the
front end 26f of the steering arm 26 upward or downward is
transmitted to the housing 34 through the bushing 52 and the
bushing holder 53, the housing 34 turns around the centerline of
the steering rod 32. Thus, the force is absorbed not only by the
bushing 52 turning relative to the bushing holder 53 but also by
the housing 34 turning relative to the steering rod 32. It is
thus possible to absorb a greater force.
[0133] In the present preferred embodiment, the bushing 52 is
located behind the steering tube 33 and thus does not overlap
the steering tube 33 in a side view. With the conventional
vessel propulsion apparatus described above, the pivot member is
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located in the piston member. Thus, as compared with the
conventional vessel propulsion apparatus described above, the
structure of the steering tube 33 is simplified. Furthermore,
since the steering tube 33 is shortened in the right-left
direction as compared with the conventional vessel propulsion
apparatus described above, the moving range of the steering tube
33 is enlarged in the right-left direction, and the steered
angle of the outboard motor main body 2 (the rotation angle
around the centerline of the steering shaft 23) is also
increased.
[0134] In the present preferred embodiment, when the outboard
motor main body 2 rotates upward or downward around the tilt
axis At, the steering tube 33 also rotates upward or downward
around the tilt axis At. In a case in which the steering tube 33
overlaps the tilt axis At in a side view, the volume of the
space through which the steering tube 33 passes when the
steering tube 33 rotates around the tilt axis At is smaller as
compared with a case in which the steering tube 33 does not
overlap the tilt axis. Therefore, a space inside the hull H1 in
which a portion of the outboard motor main body 2 is disposed
when the outboard motor main body 2 is tilted up is reduced.
Accordingly, the space inside the hull H1 is effectively
utilized.
[0135] In US 7,311,571 B1 described above, since the steering
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cylinder is disposed between the transom bracket and the cowl of
the outboard motor, it is necessary to ensure a space, in which
the steering cylinder is disposed, between the transom bracket
and the cowl of the outboard motor. In the present preferred
embodiment, the steering tube 33 is surrounded in a side view by
the inner circumferential surface 18i of the swivel support 18
of the clamp bracket 16. Thus, it is not necessary to provide
the space, in which the steering tube 33 is disposed, between
the clamp bracket 16 and the engine cowl 12 of the outboard
motor main body 2. Furthermore, since the steering tube 33 moves
into the inner circumferential surface 18i of the swivel support
18 of the clamp bracket 16, the clamp bracket 16 need not be
disposed laterally of the moving range of the steering tube 33.
Thus, the pair of clamp brackets 16 are prevented from
increasing in size in the right-left direction.
[0136] When the outboard motor main body 2 rotates in the
right-left direction around the centerline of the steering shaft
23, the outboard motor main body 2 approaches the right or left
clamp bracket 16. If the width between the pair of clamp
brackets 16 in the right-left direction is large, the outboard
motor main body 2 may come into contact with the clamp bracket
16. Thus, in order to prevent this, the clamp brackets 16 need
to be shortened in the front-rear direction or reduced in size
in the right-left direction. In the present preferred
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embodiment, since the width between of the pair of clamp
brackets 16 is reduced, it is not necessary to take such
measures.
[0137] In the present preferred embodiment, the steering tube
33 moves in the axial direction of the steering rod 32 along the
steering rod 32. If the steering rod 32 is long, the range in
which the steering tube 33 is movable is enlarged. If the range
in which the steering tube 33 is movable is large, the steered
angle of the outboard motor main body 2 is increased. The
steering rod 32 is elongated so as to penetrate through the
clamp brackets 16. Therefore, the range in which the steering
tube 33 is movable is enlarged, and the steered angle of the
outboard motor main body 2 is increased.
[0138] In the present preferred embodiment, the tubular
portion 21 corresponding to a tilt shaft is provided on the
swivel bracket 19. The swivel bracket 19 is rotatable around the
tubular portion 21 with respect to the clamp bracket 16. The
steering tube 33 is movable to the inside of the tubular portion
21. In other words, a tilt shaft to be inserted in the clamp
bracket 16 defines, inside the clamp bracket 16, a space in
which the steering tube 33 is disposed. Accordingly, while a
moving range of the steering tube 33 is maintained, the width
between the pair of clamp brackets 16 is reduced.
CA 3048282 2019-06-28
Other Preferred Embodiments
[0139] The present invention is not restricted to the
contents of the preferred embodiments described above, and
various modifications are possible.
[0140] For example, instead of the ball bushing 52, the
motion converter 51 of the steering device 4 may include a
cylindrical bushing extending in the up-down direction and a
cylindrical bushing extending in the right-left direction. In
this case, the cylindrical bushing extending in the right-left
direction is retained in the bushing holder 53, and disposed
between the bushing holder 53 and the steering arm 26.
[0141] When the outboard motor main body 2 is located at the
right maximum steered position or the left maximum steered
position, the front end 26f of the steering arm 26 may be
located within the insertion hole 52h of the bushing 52. In this
case, the front end 26f of the steering arm 26 may be located in
front of the center of the bushing 52 (the point through which
the turning axis Al passes in Fig. 8) which defines a midpoint
of the bushing 52, or may be located behind the center of the
bushing 52.
[0142] The bushing 52 may be disposed not behind the steering
tube 33 but below or above the steering tube 33.
[0143] The width of the arm-insertion hole 54h of the main
holder 54 may be constant from the front end of the arm-
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insertion hole 54h to the rear end of the arm-insertion hole
54h.
[0144] The housing 34 of the steering device 4 may be non-
rotatable around the centerline of the steering rod 32 relative
to the steering rod 32.
[0145] Even if the housing 34 does not rotate relative to the
steering rod 32, when a force to move the front end 26f of the
steering arm 26 upward or downward in a diagonally rearward
direction is generated, the bushing 52 turns relative to the
bushing holder 53 around the turning axis A2 that passes through
the bushing 52 and that extends in the right-left direction
while the bushing 52 slides on the bushing holder 53. Thus, the
bushing 52 is prevented from being pressed against the bushing
holder 53 at high pressure.
[0146] The centerline of the steering tube 33 and the
steering rod 32 need not to be located on the tilt axis At. In
this case, the steering tube 33 and the steering rod 32 may or
may not overlap the tilt axis At in a side view.
[0147] The steering tube 33 may reciprocate in the right-left
direction within the housing 20 of the swivel bracket 19 without
entering into the tubular portion 21 of the swivel bracket 19.
[0148] The steering actuator 31 may be disposed outside the
housing 20 of the swivel bracket 19. In this case, the steering
rod 32 may not penetrate the clamp bracket 16 in the right-left
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direction.
[0149] The tubular portion 21 that is inserted into the inner
circumferential surface 18i of the swivel support 18 of the
clamp bracket 16 may be a member that is separate from the
housing 20 of the swivel bracket 19. In this case, the tubular
portion 21 may be fixed to the swivel bracket 19 by press
fitting, welding, or bolting, or by any method other than these.
[0150] Features of two or more of the various preferred
embodiments described above may be combined.
[0151] 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.
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