Steering system for outboard drive

Abstract

A steering system for an outboard drive includes a steering handle furnished on a watercraft, a steering device, a lever that has first and second ends, and a sensor. The first end of the lever is attached to the drive. The sensor senses an actual position of the steering handle to provide a position signal to the steering device. The steering device includes an electric motor that has an outer casing and a ball screw extending through the outer casing. The ball screw and the outer casing move relative to one another in accordance with the actual position of the steering handle. The second end of the lever is attached to the ball screw or the outer casing. The ball screw or the outer casing steers the drive through the lever.

Description

PRIORITY INFORMATION

The present application is based on and claims priority under 35 U.S.C. § 119 to Japanese Patent Application No. 2004-000219, filed on Jan. 5, 2004, Japanese Patent Application No. 2004-000264, filed on Jan. 5, 2004, and Japanese Patent Application No. 2004-000267, filed on Jan. 5, 2004, the entire contents of which are expressly incorporated by reference herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to a steering system for an outboard drive, and more particularly relates to an improved steering system that incorporates an electric motor for steering an outboard drive.

2. Description of Related Art

Many watercraft are propelled by one or more outboard motors mounted on a transom board. A typical outboard motor has a drive unit and a bracket assembly. The drive unit incorporates a propulsion device (e.g., a propeller) that propels the watercraft. The bracket assembly is mounted on the watercraft to support the drive unit and to enable pivotal movement of the drive unit about a steering axis. In a typical outboard motor, the steering axis is defined by a steering shaft coupled with the drive unit and extending vertically through the bracket assembly.

The typical watercraft includes a steering system that incorporates a steering handle (e.g., a steering wheel). The steering handle is operable by the operator of the watercraft. A steering device is responsive to movements of the steering handle and is coupled with the steering shaft to cause the steering shaft to move in accordance with the movement of the steering handle.

In some typical systems, a hydraulically operable steering device moves the steering shaft. Such a steering device includes a hydraulic system that occupies a relatively large space. The hydraulic system also includes a pipe arrangement that makes the steering device complicated.

A steering device incorporating an electric motor can replace the hydraulic steering device. For example, Japanese Patent No. 2959044 discloses an electrical steering device having an electric motor, a rack and pinion mechanism, and a link mechanism. The electric motor drives a pinion of the rack and pinion mechanism to axially move a rack thereof, and the link mechanism rotates the steering shaft in accordance with the axial movement of the rack. The drive unit can thus change its position about the steering axis, thereby, turning the watercraft left or right.

In the steering device disclosed in the above-referenced Japanese patent, the electric motor and the rack and pinion mechanism are disposed in a relatively large body positioned within the watercraft in front of the transom board. Thus, the steering device occupies a significant volume of space inside the watercraft or can interfere with other components in the watercraft.

SUMMARY OF THE INVENTION

An aspect of the present invention is recognition of the need for an outboard drive with an improved steering system with a simple and compact steering device for moving the steering shaft about the steering axis. To address such a need, an aspect of the present invention involves a steering system for an outboard drive that comprises a steering handle adapted to be finished on a watercraft, a steering device, a lever that has first and second ends, and a sensor. The first end of the lever is attached to the drive. The sensor senses an actual position of the steering handle to provide a position signal to the steering device. The steering device comprises an electric motor that has an outer casing and a ball screw arranged to extend through the outer casing. The ball screw and the outer casing move relative to one another in accordance with the actual position of the steering handle. The second end of the lever is attached to the ball screw or the outer casing. The ball screw or the outer casing steers the drive through the lever.

In accordance with another aspect of the present invention, an outboard drive system comprises a drive unit. A steering shaft is attached to the drive unit and extends generally vertically. A swivel bracket is arranged to journal the steering shaft for steering movement of the drive unit about a steering axis. A clamping bracket can be mounted on the watercraft. A tilt pin extends generally horizontally through the swivel bracket and the clamping bracket. The clamping bracket supports the swivel bracket with the drive unit for tilt movement about a tilt axis. A lever has first and second ends. The first end of the lever is attached to the steering shaft. A steering device includes an electric motor that has an outer casing and a ball screw arranged to extend through the outer casing. The ball screw and the outer casing move relative to each other. The second end of the lever is attached to the ball screw or the outer casing. The ball screw or the outer casing moves the steering shaft about the steering axis through the lever.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects and advantages of the present invention are described below with reference to the drawings of preferred embodiments, which embodiments are intended to illustrate and not to limit the present invention.

FIG. 1 illustrates a top plan view of an outboard motor mounted on a watercraft, and illustrates a steering system that is configured in accordance with certain features, aspects and advantages of the present invention.

FIG. 2 illustrates an enlarged top plan view of the outboard motor with a steering device of the steering system of FIG. 1.

FIG. 3 illustrates an enlarged top plan view of a portion of the outboard motor and the steering device, wherein the portion of the outboard motor is partially cross-sectioned.

FIG. 4 illustrates a front elevation view of the portion of the outboard motor and the steering device shown in FIG. 3.

FIG. 5 illustrates a side elevation view of the portion of the outboard motor and the steering device shown in FIG. 3, wherein a swivel bracket of the outboard motor is positioned in a tilted down position.

FIG. 6 illustrates a side elevation view of the portion of the outboard motor and the steering device of FIG. 3, wherein the swivel bracket is positioned in a tilted up position.

FIG. 7 illustrates an enlarged top plan view of a portion of an outboard motor and another steering device modified in accordance with a second embodiment of the present invention, wherein the portion of the outboard motor is partially cross-sectioned.

FIG. 8 illustrates a front elevation view of the portion of the outboard motor and the steering device of FIG. 7.

FIG. 9 illustrates an enlarged top plan view of a portion of an outboard motor and a further steering device modified in accordance with a third embodiment of the present invention, wherein the portion of the outboard motor is partially cross-sectioned.

FIG. 10 illustrates a front elevation view of the portion of the outboard motor and the steering device of FIG. 9.

FIG. 11 illustrates an enlarged top plan view of a portion of an outboard motor and a further steering device modified in accordance with a fourth embodiment of the present invention, wherein the portion of the outboard motor is partially cross-sectioned.

FIG. 12 illustrates a front elevation view of the portion of the outboard motor and the steering device of FIG. 11.

FIG. 13 illustrates a top plan view of an outboard motor mounted on a watercraft, and illustrates a steering system that is modified in accordance with a fifth embodiment of the present invention.

FIG. 14 illustrates an enlarged top plan view of a portion of the outboard motor of FIG. 13 and a steering device of the steering system of FIG. 13, wherein a portion of the outboard motor partially cross-sectioned.

FIG. 15 illustrates a front elevation view of the portion of the outboard motor and the steering device of FIG. 13, wherein a portion of the steering device associated with a left hand portion of the outboard motor in the figure illustrates a variation of the steering device of FIG. 14.

FIG. 16 illustrates a top plan view of an outboard motor mounted on a watercraft, and illustrates a steering system that is modified in accordance with a sixth embodiment of the present invention.

FIG. 17 illustrates an enlarged top plan view of a portion of the outboard motor of FIG. 16 and a steering device of the steering system of FIG. 16.

FIG. 18 illustrates a front elevation view of the portion of the outboard motor and the steering device of FIG. 16.

FIG. 19 illustrates an enlarged top plan view of a portion of an outboard motor and a further steering device modified in accordance with a seventh embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

FIGS. 1-6 illustrate a steering system 30 configured in accordance with certain features, aspects and advantages of one embodiment of the present invention for an outboard motor 32. The outboard motor 32 merely exemplifies one type of outboard drive. The steering system 30 can be used with other types of outboard drives such as, for example, stern drives for inboard/outboard systems. Such applications will be apparent to those of ordinary skill in the art in view of the description herein.

The outboard motor 32 preferably comprises a drive unit 34 and a bracket assembly 36. The drive unit 34 preferably comprises a housing unit and a power head disposed atop the drive unit 34 and above the housing unit. The housing unit preferably comprises a driveshaft housing and a lower unit extending below the driveshaft housing. The bracket assembly 36 supports the drive unit 34 on a transom 38 of an associated watercraft 40 and places a marine propulsion device (not shown) in a submerged position, with the watercraft 40 resting on the surface of a body of water. Preferably, the marine propulsion device is a propeller.

As used in this description, the terms “forward,” “forwardly” and “front” mean at or to the side where the bracket assembly 36 is located, and the terms “rear,” “reverse,” “backward” and “rearward” mean at or to the opposite side of the front side, unless indicated otherwise or otherwise readily apparent from the context use. As further used in this description, the term “horizontally” means that the subject portions, members or components extend generally parallel to the water surface when the watercraft 40 is substantially stationary with respect to the water surface and when the drive unit 34 is not tilted. The term “vertically” means that portions, members or components extend generally normal to those that extend horizontally.

As shown in FIGS. 3 and 4, the bracket assembly 36 preferably comprises a swivel bracket 44, a clamping bracket 46, a steering shaft 48 and a tilt pin (or pivot pin) 50. The steering shaft 48 preferably extends generally vertically through the swivel bracket 44 and is affixed to the housing unit through upper and lower mount assemblies. The steering shaft 48 is pivotally journaled within the swivel bracket 44 for steering movement about a steering axis defined by the steering shaft 48. The steering axis extends vertically along a center plane CP (FIGS. 2-4) that extends vertically and fore to aft relative to the outboard motor 32. The drive unit 34 pivots about the steering axis relative to the swivel bracket 44 because the steering shaft 48 is affixed to the drive unit 34.

In the illustrated embodiment, a steering lever 52 preferably is affixed to a top end of the steering shaft 48 to extend forward. The steering lever 52 has a forward end 54 and a rear end 55, and the steering lever 52 preferably is affixed to the steering shaft 48 at the rear end 55 thereof. As thus constructed, the drive unit 34 is steerable about the steering axis when the steering lever 52 moves the steering shaft 48 right and left. In the illustrated embodiment, a steering device 56 is provided on the bracket assembly 36 to move the steering lever 52.

The clamping bracket 46 comprises two bracket arms 58 that are spaced from each other to interpose the swivel bracket 44 there between, and the respective bracket arms 58 are affixed to the watercraft transom 38 (FIG. 2) by clamping bolts. Preferably, the clamping bolts are previously inserted into suitable bolt holes 60 in the bracket arms 58. The tilt pin 50 extends generally horizontally through the swivel bracket 44 and the bracket arms 58 of the clamping bracket 46 to complete a hinge coupling between the swivel bracket 44 and the clamping bracket 46. The clamping bracket 46 thus supports the swivel bracket 44 and the drive unit 34 for pivotal movement about a tilt axis defined by the tilt pin 50. The tilt pin 50 preferably is pivotally affixed to the bracket arms 58 by nuts 62 shown in FIG. 3. In the illustrated embodiment, each end portion of the tilt pin 50 extends outward beyond the nuts 62.

A tilt and trim adjustment device 64 (FIG. 4) preferably is provided between the swivel bracket 44 and the clamping bracket 46 to tilt (raise or lower) the swivel bracket 44 together with the drive unit 34 relative to the clamping bracket 46. The tilt and trim adjustment device 64 preferably comprises a hydraulically operated mechanism that includes a hydraulic cylinder 66, a hydraulic piston that reciprocates within the cylinder 66, a hydraulic pump 68 that powers the piston, and a fluid reservoir 70 that stores a working fluid such as oil. A piston rod extends outward beyond one end of the cylinder 66. Preferably, a bottom end of the cylinder 66 is pivotally affixed to the clamping bracket 46 while a top end of the piston rod is pivotally affixed to the swivel bracket 44.

When the hydraulic pump 68 operates, the piston rod extends from the cylinder 66 or retracts into the cylinder 66 in response to the movement of the working fluid within the cylinder 66. When the piston rod extends, the swivel bracket 44 and the drive unit 34 are tilted upward. With the piston rod retracts, the swivel bracket 44 and the drive unit 34 are tilted downward. Preferably, the drive unit 34 moves between a fully tilted down position that is the most lowered position of the drive unit 34 and a fully tilted up position that is the most raised position of the drive unit 34 when the tilt and trim adjustment device 64 is activated. Preferably, a lower tilt range is a trim adjustment range.

The power head comprises a prime mover, which in this embodiment is an internal combustion engine such as, for example, a four-cycle engine or two-cycle engine. Other prime movers such as, for example, an electric motor, can replace the engine. The power head further comprises a protective cowling assembly. Preferably, the protective cowling assembly defines a generally closed cavity, and the engine is disposed within the protective cowling assembly.

As illustrated in FIG. 1, the steering system 30 comprises a steering handle such as, for example, a steering wheel 72, a steering column 74, a steering position sensor 76, an electric cable 78, a steering controller 80 and the foregoing steering device 56. The steering column 74 preferably extends upward and rearward from a forward bottom of a cockpit of the watercraft 40 and is supported by a journal for rotation. The steering wheel 72 is disposed atop the steering column 74 in a position so that an operator of the watercraft 40 can turn the wheel 72. The steering position sensor 76 is positioned at a bottom of the steering column 74 to sense an actual angular position of the steering wheel 72 when the wheel is turned by the operator. The sensor 76 senses a pivot angle of the steering column 74 that corresponds to an amount of the angular movement of the steering wheel 72 from a reference position (e.g., the neutral position of the steering wheel when the watercraft is moving straight ahead without turning). The cable 78 electrically connects the sensor 76 in the forward area of the cockpit to the steering controller 80 positioned in the proximity of the steering device 56. The sensor 76 provides a position signal to the steering device 56 through the cable 78.

Alternatively, the steering controller 80 can be placed in the cockpit, for example, in the proximity of the sensor 76. In this variation, the electric cable 78 interconnects the controller 80 and an electric motor 84 of the steering device 56, which is described below.

When the operator turns the steering wheel 72 clockwise or counterclockwise, the steering column 74 rotates with the steering wheel 72, and the steering position sensor 76 senses a position of the steering wheel 72. A signal indicating the sensed position of the steering wheel 72 is transmitted to the steering controller 80. The controller 80 controls the steering device 56 to move the steering lever 52 to the right or to the left in accordance with the position of the steering wheel 72.

The cable 78 can be formed in a variety of configurations. For example, electrical conductors or optical fibers can be used. In one variation, the cable 78 is replaced by a wireless transmitter placed at or near the sensor 76 and a wireless receiver placed at or near the controller 80.

As illustrated in FIGS. 2-5, the steering device 56 preferably comprises the electric motor 84. The electric motor 84 has an outer casing 86 and has a ball screw 88 extending through the outer casing 86. The outer casing 86 and the ball screw 88 together form a direct drive type motor (“a DD motor”). The outer casing 86 includes the remainder of the motor elements such that the outer casing 86 and the ball screw 88 together function as a motor. The steering controller 80 is electrically connected to the electric motor 84 to control the motor 84. The ball screw 88 comprises an elongated screw and a plurality of balls (not shown) placed in the grooves of the screw in an area of the casing 86. The casing 86 and the screw 88 are coupled with each other via the balls in a known manner. The casing 86 and the ball screw 88 move axially relative to each other when the motor 84 is activated. More specifically, the controller 80 activates and controls the motor 84 to move the outer casing 86 or the ball screw 88 relative to one another in response to the actual position of the steering wheel 72. The steering lever 52 converts the axial movement of the outer casing 86 or the ball screw 88 to a pivotal movement of the steering shaft 48. Additionally, the electric motor 84 is connected to receive electrical power from a battery or batteries (not shown).

In the illustrated embodiment shown in FIG. 3, a cylindrical motor housing 92 extends parallel to the tilt pin 50 and holds the outer casing 86. The ball screw 88 also extends parallel to the tilt pin 50. Preferably, the outer casing 86 is affixed to an inside wall of the motor housing 92 at a center location by bolts or by other suitable fixing elements such as, for example, a bonding agent. Preferably, the motor housing 92 is sufficiently longer than the casing 86 to protect the ball screw 88, because the ball screw 88 in the illustrated embodiment is longer than the tilt pin 50.

A support member or support unit preferably extends from the tilt pin 50 to support the ball screw 88. In the illustrated embodiment, the support unit is formed by two support members 94 that are mounted onto respective end portions of the tilt pin 50 and that generally extend forwardly from the tilt pin 50. The respective support members 94 are positioned symmetrically relative to the center plane CP.

Each support member 94 is generally configured as a shape of the letter “S.” A rear end of the support member 94 has an opening through which an end portion of the tilt pin 50 extends. A forward end of the support member 94 also has an opening through which an end of the ball screw 88 extends. The rear end of each support member 94 is attached to one end portion of the tilt pin 50 such that a spacer 96 is interposed between the nut 62 and the rear ends of the support member 94. The forward end of each support member 94 is attached to a respective end of the ball screw 88. Preferably, a distance between the forward ends of the support members 94 is longer than a distance between the rear ends of the support members 94, because the ball screw 88 is longer than the tilt pin 50. In the illustrated embodiment, nuts 98 fix the rear ends of the support members 94 onto the tilt pin 50, while nuts 100 fix the forward ends of the support members 94 onto the ball screw 88. In alternative embodiments, a single support member 94 of sufficient strength may be used to support the ball screw 88. As thus constructed, the ball screw 88 is affixed to the tilt pin 50 and can pivot about the tilt axis when the drive unit 34 tilts up or down.

A link unit couples the forward end 54 of the steering lever 52 with the outer casing 86 of the electric motor 84. The link unit preferably comprises a link member 102 and a connecting pin 104. In the illustrated embodiment, the motor housing 92 is coupled with the link member 102 to be a part of the link unit.

The link member 102 preferably is a metal plate that generally has a half elliptic shape. As shown in FIG. 4, a center area 102a of the link member 102 is slightly recessed such that both side areas 102b of the link member 102 are positioned higher than the center area 102a when the link member 102 is positioned above the motor housing 92. As shown in FIG. 3, the link member 102 preferably has a slot 105 in the center area 102a. The connecting pin 104 preferably extends from the lever 52 and extends through the slot 105 of the link member 102 to couple the lever 52 and the link member 102 with each other. The slot 105 is loose enough for the pin 104 to move back and forth therein. In the illustrated embodiment, both the steering axis and an axis of the pin 104 are positioned on the center plane CP when the drive unit 34 is not steered. The recessed configuration of the link member 102 is advantageous because the position of the drive unit 34 can be lowered to lower the center of gravity of the outboard motor 30 to increase the stability of the watercraft 40.

The motor housing 92 has two bosses 108 (FIG. 4) that extend upward from a top surface of the motor housing 92. The link member 102 is affixed to the motor housing 92 by bolts 110 at the respective bosses 108. The bolts 110 enable the motor housing 92 and the link member 102 to be easily and rigidly coupled together. In one variation, the link member 102 is unitarily formed with the motor housing 92 such that the link unit is simpler.

As thus constructed, the motor housing 92 is movable along the ball screw 88, and the ball screw 88 is not movable because the ball screw 88 is rigidly affixed to the tilt pin 50. The motor housing 92 thus moves axially along the ball screw 88 accordingly in this embodiment when the electric motor 84 is activated.

The motor housing 92 is placed in the center of the ball screw 88 such that the center of the outer casing 86 is positioned on the center plane CP when the steering wheel 72 is in a neutral position (e.g., a non-turning position). Thus, the illustrated steering device 56 is positioned symmetrically relative to the center plane CP when the steering angle is zero. The motor housing 92 and the outer casing 86 are positioned at a reference position that corresponds to a reference position of the steering wheel 72. The steering angle is zero at those reference positions. The pin 104 is positioned at the forward-most end of the slot 105 under these conditions.

When the operator turns the steering wheel 72 clockwise or counterclockwise, the sensor 76 senses an actual position of the steering wheel 72 and transmits a position signal to the controller 80 through the cable 78. The controller 80 activates and controls the electric motor 84. The outer casing 86 of the electric motor 84 and the housing 92 move along the ball screw 88 to the right or to the left as indicated by the arrow A of FIG. 2 under control of the controller 80. The movement of the housing 92 causes the pin 104 to move rearward within the slot 105 and causes the lever 52 turn with a certain angle that the controller 80 indicates. For example, as illustrated in FIG. 1, when the operator turns the steering wheel 72 clockwise as indicated by the arrow B, the lever 52 turns counterclockwise as indicated by the arrow C, and the drive unit 34 also turns counterclockwise as indicated by the arrow D. This position of the drive unit 34 causes the watercraft 40 to turn right in response to the operator action.

As illustrated in FIGS. 5 and 6, the steering device 56 is able to pivot about the tilt axis because the support members 94 are affixed to the tilt pin 50. As shown in FIG. 5, the link member 102 generally extends horizontally when the drive unit 34 is in a tilted down position. In contrast, when the drive unit 34 is fully tilted up as illustrated in FIG. 6, the link member 102 is inclined and the steering device 56 is positioned lower than the tilt pin 50.

In the illustrated embodiment, the connecting pin 104 extends from the steering lever 52, and the slot 105 is located at the link member 102. Alternatively, the connecting pin 104 can extend from the link member 102 with the slot 105 located at the steering lever 52. In this alternative, the pin 104 is positioned at the rear-most end of the slot 105 when the drive unit 34 is positioned for straight ahead movement (e.g., no turning).

The steering device 56 of the steering system 30 in the illustrated embodiment has a simple and compact arrangement because the electric motor 84 is disposed in the motor housing 92 that extends along the ball screw 88 and has no rack and pinion mechanism. The illustrated ball screw 88 is located close to the tilt pin 50 because the ball screw 88 is supported by the tilt pin 50. This arrangement makes the portion of the steering device 56 situated within the watercraft 40 smaller than in a system using known steering devices.

FIGS. 7 and 8 illustrate a steering system 116 modified in accordance with a second embodiment of the present invention. The members, components, and devices that are the same as those described above are assigned the same reference numerals in the embodiment of FIGS. 7 and 8 and in other embodiments described below, and will not be described again unless required in the context of the description of another element.

The steering system 116 of FIGS. 7 and 8 includes a steering device 118. The steering device 118 incorporates a modified motor housing 120 that preferably has a housing body 122 and two housing arms 124. The housing body 122 generally extends parallel to the tilt pin 50 and holds the outer casing 86 of the electric motor 84. The respective housing arms 124 extend from respective ends of the housing body 122 toward the tilt pin 50 and are affixed to the end portions of the tilt pin 50.

Preferably, a link rod 128 connects the steering lever 52 with the ball screw 88. In this second embodiment, the steering lever 52 does not have a slot Instead, the link rod 128 is affixed to the lever 52 by a ball joint 130 that has a pin 132. Also, the link rod 128 is affixed to one end of the ball screw 88 by another ball joint 134 that has a pin 136.

Because the outer casing 86 is affixed to the tilt pin 50 via the motor housing 120, while the ball screw 88 is free to move relative to the outer casing 86 in the second embodiment, the ball screw 88 extends from or retracts into the housing 120. With the movement of the ball screw 88, the steering lever 52 pivots about the steering axis. Thus, the drive unit 34 moves clockwise or counterclockwise to turn the watercraft 40 to the left or to the right respectively. The ball joints 130, 134 allow the swivel bracket 44 with the drive unit 34 to tilt up and down even though the motor housing 120 is affixed to the tilt pin 50. Also, the ball joints 130, 134 allow greater tolerance in the dimensions of the components of the steering system 116. The arrangement of the second embodiment also allows the tilt pin 50 to be shorter.

FIGS. 9 and 10 illustrate a further steering system 140 modified in accordance with a third embodiment of the present invention. The steering system 140 incorporates a modified steering device 141 that has a movable motor housing 92. In the third embodiment, modified support members 142 are applied to support the ball screw 88 on the swivel bracket 44 rather than on the tilt pin 50. The steering device 141 includes two bosses 143 that preferably project toward the motor housing 92 from top forward ends of the swivel bracket 44. The support members 142 are affixed to the respective bosses 143 by bolts 144. Because the ball screw 88 is affixed to the swivel bracket 44, the tilt pin 50 does not need to extend outward and can be shorter in the third embodiment.

FIGS. 11 and 12 illustrate a further steering system 148 modified in accordance with a fourth embodiment of the present invention. The steering system 148 incorporates a modified steering device 150 that has the movable ball screw 88. The motor housing 92 preferably has bosses 152 that project toward the bosses 143 of the swivel bracket 44. The motor housing 92 is affixed to the swivel bracket 44 at the bosses 152 by bolts 154. The bolts 154 are schematically shown in actual lines in the figure, although a large part of each bolt 154 is hidden by the motor housing 92 during normal viewing.

FIGS. 13-15 illustrate a further steering system 160 modified in accordance with a fifth embodiment of the present invention. The steering system 160 incorporates a modified steering device 162 that has the movable ball screw 88. The illustrated ball screw 88 extends coaxially with a modified tilt pin 164 that is hollowed. Thus, the illustrated tilt pin 164 is configured as a pipe, and the ball screw 88 extends through the pipe. The ball screw 88 has a center axis E that is identical to the tilt axis of the tilt pin 164. The tilt pin 164 preferably has a relatively large diameter so that the tilt pin 164 is also a motor housing that holds the outer casing 86. Preferably, the steering device 162 includes collars 166 that are inserted into the tilt pin 164 to hold the ball screw 88 therein. The collars 166 space the ball screw 80 apart from the swivel bracket 44.

Alternatively, as shown in the left hand side of the tilt pin 164 of FIG. 15, each bracket arm 58 of the clamping bracket 46 has a cylindrical projection or boss 168 that unitarily extends from the bracket arm 58. Each projection 168 is inserted into an opening 169 of the swivel bracket 44 to space the ball screw 88 apart from the swivel bracket 44.

When constructed as shown in FIGS. 13-15, the steering device 162 in the fifth embodiment is extremely compact and does not protrude into the watercraft.

FIGS. 16-18 illustrate a further steering system 170 modified in accordance with a sixth embodiment of the present invention. The steering system 170 incorporates a modified steering device 172 that has the movable ball screw 88. A motor housing 174 of the sixth embodiment is attached to the transom 38 of the watercraft 40. A bracket 176 preferably is affixed to a portion of the transom 38 by bolts 178 in close proximity to one side corner of the watercraft 40. Preferably, a first end portion 180 of the motor housing 174 is affixed to the bracket 176 via a ball joint 182. A second end portion, which is opposite to the first end portion 180, comprises the outer casing 86. The ball screw 88 extends through the motor housing 174 and further extends outward from the outer casing 86. An end 184 of the ball screw 88 is affixed to a forward end 54 of the steering lever 52 via a ball joint 186 by a pin 188. In FIG. 18, one nut 62 couples the tilt pin 50 with the clamping bracket 46. Preferably, another nut is affixed to another side of the tilt pin 50 to couple the tilt pin 50 to another side of the clamping bracket 46.

Because the motor housing 174 is attached to the transom 38 of the watercraft 40, the tilt pin 50 can be short enough to be covered by the power head of the drive unit 34. The electric cable 78 in the sixth embodiment is located away from the drive unit 34. Thus, the cable 78 does not bend and stretch much even though the drive unit 34 tilts up and down. The life span of the cable 78 may thus be extended.

In the illustrated embodiment, the controller 80 is attached to the electric motor 86. As noted above, the controller 80 can be separated from the electric motor 86 and can be placed close to the sensor 76. In this variation, the steering device 172 can be more compact.

FIG. 19 illustrates a further steering system 190, which is modified in accordance with a seventh embodiment of the present invention. The steering system 190 incorporates a modified steering device 192 that has the movable motor housing 92. In the seventh embodiment, two support members 194 preferably are affixed to the transom 38 of the watercraft 40 by bolts to support the ball screw 88. The illustrated motor housing 92 is rigidly coupled with a link member 198. The link member 198 in turn is affixed to the steering lever 52 via a ball joint 200 that has a pin 202. The pin 202 preferably is inserted into a slot (not shown) which is disposed at the lever 52.

The motor housing 92 does not move with the tilt movement of the drive unit 34 because the ball screw 88 is affixed to the transom 38. The controller 80 is affixed to the housing 92. Thus, the electric cable 78 does not bend and stretch much even though the drive unit 34 tilts up and down. The life span of the cable 78 in the seventh embodiment may also be extended, accordingly.

Although this invention has been disclosed in the context of certain preferred embodiments, it will be understood by those skilled in the art that the present invention extends beyond the specifically disclosed embodiments to other alternative embodiments and/or uses of the invention and obvious modifications and equivalents thereof. It is also contemplated that various combinations or sub-combinations of the specific features and aspects of the embodiments may be made and still fall within the scope of the invention. It should be understood that various features and aspects of the disclosed embodiments can be combined with or substituted for one another in order to form varying modes of the disclosed invention. Thus, it is intended that the scope of the present invention herein disclosed should not be limited by the particular disclosed embodiments described above, but should be determined only by a fair reading of the claims that follow.

Claims

1. A steering system for an outboard drive comprising a steering handle adapted to be furnished on a watercraft, a steering device, a lever having first and second ends, the first end being attached to the drive, and a sensor sensing an actual position of the steering handle to provide a position signal to the steering device, the steering device comprising an electric motor having an outer casing and a ball screw arranged to extend through the outer casing, the ball screw and the outer casing moving relative to one another in accordance with the actual position of the steering handle, the second end of the lever being attached to the ball screw or the outer casing, the ball screw or the outer casing steering the drive through the lever.

2. The steering system as set forth in claim 1, wherein the drive comprises a drive unit, a steering shaft that is attached to the drive unit and that extends generally vertically, a swivel bracket arranged to journal the steering shaft for steering movement of the drive unit about a steering axis, a clamping bracket adapted to be mounted on the watercraft, a tilt pin extending generally horizontally through the swivel bracket and the clamping bracket, the clamping bracket supporting the swivel bracket with the drive unit for tilt movement about a tilt axis, a support member or support unit arranged to extend from the tilt pin or the swivel bracket to support the ball screw, and a link unit arranged to couple the second end of the lever with the outer casing of the electric motor.

3. The steering system as set forth in claim 2, wherein the support unit comprises a pair of support members attached to respective ends of the tilt pin.

4. The steering system as set forth in claim 2, wherein the link unit includes a link member and a connecting pin, the link member being connected to the second end of the lever via the connecting pin.

5. The steering system as set forth in claim 2, wherein the first end of the lever is attached to the steering shaft.

6. The steering system as set forth in claim 1, wherein the drive comprises a drive unit, a steering shaft that is attached to the drive unit and that extends generally vertically, a swivel bracket arranged to journal the steering shaft for steering movement of the drive unit about a steering axis, a clamping bracket adapted to be mounted on the watercraft, a tilt pin extending generally horizontally through the swivel bracket and the clamping bracket, the clamping bracket supporting the swivel bracket with the drive unit for tilt movement about a tilt axis, a support member arranged to extend from the tilt pin or the swivel bracket to support the outer casing of the electric motor, and a link member arranged to extend from the second end of the lever to be coupled to the ball screw.

7. The steering system as set forth in claim 6, wherein the support member has first and second ends coupled to respective ends of the tilt pin, and the support member supports the outer casing of the electric motor between the first and second ends.

8. The steering system as set forth in claim 6, wherein the link member has a first end coupled to the second end of the lever through a first ball joint and has a second end coupled to the ball screw through a second ball joint.

9. The steering system as set forth in claim 1, wherein the drive comprises a drive unit, a steering shaft attached to the drive unit and extending generally vertically, a swivel bracket arranged to journal the steering shaft for steering movement of the drive unit about a steering axis, a clamping bracket adapted to be mounted on the watercraft, and a tilt pin extending generally horizontally through the swivel bracket and the clamping bracket, wherein the clamping bracket supports the swivel bracket with the drive unit for tilt movement about a tilt axis, wherein the tilt pin is hollowed to support the outer casing of the electric motor therein, wherein the ball screw coaxially extends through the tilt pin, and wherein a link member is arranged to extend from the second end of the lever to be coupled to the ball screw.

10. The steering system as set forth in claim 1, wherein the drive comprises a drive unit, a steering shaft attached to the drive unit and extending generally vertically, a swivel bracket arranged to journal the steering shaft for steering movement of the drive unit about a steering axis, a clamping bracket adapted to be mounted on the watercraft, and a tilt pin extending generally horizontally through the swivel bracket and the clamping bracket, wherein the clamping bracket supports the swivel bracket with the drive unit for tilt movement about a tilt axis, wherein the ball screw is coupled to the second end of the lever, and wherein the outer casing of the electric motor is adapted to be attached to the watercraft or is attached to the clamping bracket.

11. The steering system as set forth in claim 10, wherein the ball screw and the second end of the lever are coupled together through a ball joint.

12. The steering system as set forth in claim 1, wherein the drive comprises a drive unit, a steering shaft attached to the drive unit and extending generally vertically, a swivel bracket arranged to journal the steering shaft for steering movement of the drive unit about a steering axis, a clamping bracket adapted to be mounted on the watercraft, a tilt pin extending generally horizontally through the swivel bracket and the clamping bracket, wherein the clamping bracket supports the swivel bracket with the drive unit for tilt movement about a tilt axis, wherein a support member adapted to be attached to a transom of the watercraft or attached to the clamping bracket to support the ball screw, and wherein a link member arranged to extend from the second end of the lever to be coupled to the outer casing of the electric motor.

13. The steering system as set forth in claim 12, wherein the link member and the second end of the lever are coupled together through a ball joint.

14. The steering system as set forth in claim 1, wherein the outer casing of the electric motor is generally positioned at a center of the ball screw when a steering angle is zero.

15. An outboard drive system comprising a drive unit, a steering shaft attached to the drive unit and extending generally vertically, a swivel bracket arranged to journal the steering shaft for steering movement of the drive unit about a steering axis, a clamping bracket adapted to be mounted on the watercraft, a tilt pin extending generally horizontally through the swivel bracket and the clamping bracket, the clamping bracket supporting the swivel bracket with the drive unit for tilt movement about a tilt axis, a lever having first and second ends, the first end being attached to the steering shaft, and a steering device including an electric motor that has an outer casing and a ball screw arranged to extend through the outer casing, the ball screw and the outer casing moving relative to each other, the second end of the lever being attached to the ball screw or the outer casing, the ball screw or the outer casing moving the steering shaft about the steering axis through the lever.