Abstract:
Disclosed herein is an outboard motor for a boat having a hull and including a support adapted to be fixed relative to the boat hull, and a propulsion assembly including a rotatably mounted propeller and being connected to the support for pivotal steering movement about a steering axis. The outboard motor also includes a pair of elongated members, coupled together for linear extension and retraction upon rotation of one of the elongated members with respect to the other of the elongated members, an end of one of the members being connected to the propulsion assembly for causing pivotal movement of the propulsion assembly about the steering axis, an assembly for fixing the other of the elongated members against longitudinal movement, and a push pull cable assembly for selectively causing rotation of one of the elongated members with respect to the other of the elongated members.

Description:
FIELD OF THE INVENTION 
     The invention relates to marine steering systems and particularly to power actuated steering systems for marine propulsion devices such as outboard motors. 
     BACKGROUND PRIOR ART 
     Prior art power assisted steering arrangements for marine propulsion units are illustrated for purposes of example in the Pierson U.S. Pat. No. 2,951,460, issued Sept. 6, 1960; in the Cadwallader U.S. Pat. No. 3,051,886, issued Aug. 28, 1962; and in the Shimanckas U.S. Pat. No. 3,631,833, issued Jan. 4, 1972. 
     Attention is also directed to the Borst U.S. patent application Ser. No. 953,566, filed Oct. 28, 1978, titled &#34;Inboard-Outboard Driving Mechanism Including A Hydraulically Assisted Steering System,&#34; and assigned to the assignee of the present invention. 
     Attention is also directed to the Borst et. al. U.S. Pat. No. 4,054,102, issued Oct. 18, 1977; the Borst et al. U.S. Pat. No. 3,774,568, issued Nov. 27, 1973; and the Post U.S. Pat. No. 2,875,722; issued Mar. 3, 1959. 
     SUMMARY OF THE INVENTION 
     The invention includes an outboard motor for a boat, the outboard motor including a support adapted to be fixed relative to the boat hull, a propulsion means including a rotatably mounted propeller, means for connecting the propulsion means to the support for pivotal steering movement about a steering axis, and means for causing pivotal steering movement of the propulsion means. The steering means includes a pair of elongated members, and means for threadably coupling the elongated members together for linear extension and retraction upon rotation of one of the elongated members with respect to the other of the elongated members. One end of one of the elongated members is connected to the propulsion means for causing pivotal movement of the propulsion means about the steering axis during linear extension of the elongated members. The steering means also includes means for fixing the other of the elongated members against longitudinal movement and means for selectively causing rotation of one of the elongated members with respect to the other of the elongated members. 
     In one embodiment of the invention the means for causing pivotal steering movement includes an electric motor having an output shaft and means for selectively drivingly connecting the output shaft to one of the elongated members for rotatably driving that elongated member. 
     In one embodiment of the invention the means for causing pivotal steering movement includes means for drivingly connecting the output shaft of the electric motor to the elongated member, an input shaft having a longitudinal axis, and means for supporting the input shaft for rotation about its axis and for linear movement in the direction of its longitudinal axis. Also included are means for drivingly connecting the input shaft to the rotatable elongated member, a first friction wheel driven by the electric motor, and a second friction wheel supported for rotation with the input shaft and having an axis of rotation transverse to the axis of rotation of the first friction wheel. The second friction wheel is movable with the input shaft in the direction of the longitudinal axis of the input shaft between a first position wherein the second friction wheel engages a central portion of the first friction wheel, a second position wherein the second friction wheel engages a second portion of the first friction wheel and is rotatably driven by the first friction wheel in a first rotational direction, and a third position wherein the second friction wheel engages a third portion of the second friction wheel and is rotatably driven by the first friction wheel in a second rotational direction opposite to the first rotational direction. 
     In one embodiment of the invention the means for causing linear movement of the input shaft includes a coaxial steering cable having a core and a conduit surrounding the core, the core being movable with respect to the conduit, one of the core and the conduit being connected to the propulsion means for applying steering force to the propulsion means, and the other of the core and conduit being connected to the input shaft for causing selective movement of the shaft in the direction of its longitudinal axis. 
     The invention also includes an outboard motor for a boat, the outboard motor including a support adapted to be fixed relative to the boat hull, a propulsion means including a rotatably mounted propeller, means for connecting the propulsion means to the support for pivotal steering movement about a steering axis, and means for causing pivotal steering movement of the propulsion means. The steering means includes a member having opposite ends, one of the ends being connected to the propulsion leg, and power driven means connected to an opposite end of the member and for driving the member, the power driven means including a screw, a tube threadably housing a portion of the screw, the tube and the screw being linearly extensible in response to relative rotation between the tube and the screw, and one of the screw and the tube being connected to the member. Means are also provided for rotating one of the screw and the tube, the rotating means including an electric motor, and means for selectively drivingly connecting the electric motor to one of the screw and the tube. 
     The invention also includes an outboard motor for a boat having a hull and a transom, the outboard motor comprising a support adapted to be fixed relative to the hull, a propulsion means including a rotatably mounted propeller, means for connecting the propulsion means to the support for pivotal steering movement about a steering axis, and means for providing power assisted steering movement of the propulsion means. The power assisted steering means includes an electric motor and means operable in response to manual steering to selectively apply the output of the electric motor to effect power assisted steering movement of the propulsion means. 
     Other features and advantages of the invention are set forth in the following description and claims and in the drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a plan view of a steering system for use in steering an outboard motor and embodying the invention. 
     FIG. 2 is an elevation view of the steering mechanism shown in FIG. 1. 
    
    
     Before explaining one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, is should be understood that the phraseology and terminology employed herein is for the purpose of description and should not be regarded as limiting. 
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Illustrated in the drawings is a marine propulsion unit 10 shown for purposes of example but not by way of limitation as an outboard motor supported by the transom 14 of a boat. The outboard motor 10 generally includes a power head 16. 
     Means are further provided for supporting the motor 10 for pivotal steering movement about a generally vertical steering axis and for tilting movement about a generally horizontal axis. While the supporting means can have various constructions, in the illustrated arrangement wherein the marine propulsion device comprises an outboard motor, the supporting means includes a transom bracket 20 clamped to the transom 14 and a pivot or swivel bracket 22 connected to the transom bracket by a hollow pivot tube 24 positioned generally horizontally. The swivel bracket 22 is pivotable with respect to the transom bracket 20 about the generally horizontal axis of the pivot tube 24. The outboard motor 10 can be supported for pivotal steering movement with respect to the swivel bracket 22 by any conventional means. In the illustrated construction, however, the swivel bracket 22 includes at its rearward end, with respect to the direction of movement of the boat, a generally vertical elongated bore 26 housing a pivotal kingpin 28. The outboard motor 10 is supported by the kingpin 28 for pivotal movement with the kingpin. 
     Means are also provided for causing steering movement of the motor 10 about the axis of the kingpin 28. In the illustrated construction, the steering means includes a tiller arm 30 fixed at its rearward end to the kingpin 28 and motor 10 and including a forwardly extending arm portion 32 providing a lever arm for pivoting the kingpin 28 and the motor 10 about the axis of the kingpin. A push-pull steering cable 34 is also provided and is connected between the tiller arm 30 and a steering wheel 36 for causing pivotal steering movement of the motor 10 in response to turning of the steering wheel 36. 
     The steering means for causing push-pull movement of the cable 34 can have various configurations, but in the present construction the steering wheel 36 is connected to a rotatable shaft 38 and a pivotal lever 40 is fixed to the rotatable shaft and extends radially outwardly therefrom for arcuate movement about the axis of the shaft 38 in response to rotation of the steering wheel 36. One end of the core 42 of the cable 34 is attached to the free end of the pivotable lever 40 and an adjacent end of the conduit or outer casing 44 of the cable 34 is fixedly supported by a bracket 46. Pivotable movement of the steering wheel 36 results in slidable movement of the core 42 within the conduit 44. 
     Means are also provided for attaching the movable core 42 of the steering cable 34 to the forwardly extending end 32 of the tiller arm 30 for causing pivotal steering movement thereof. While the means for attaching the core 42 of the steering cable 34 to the tiller arm 30 can have various constructions, in the illustrated arrangement such means includes a drag link 48 having one end pivotally attached to a coupler 50 and an opposite end pivotally attached to the free end 32 of the tiller arm 30. The end of the cable 34, opposite that end connected to the steering wheel 36 is connected to a cable anchor assembly 49 comprising a tube 51 fixed to the end of the conduit 44 and fixedly joined to a support block 52. A central rod 53 is fixed to the core 42 of cable 34 and is slideably supported in the tube 51. The free end of the rod 53 is connected to the coupler 50. 
     Means are also included for providing power assisted steering movement of the motor 10 about the steering axis, such steering assist means including apparatus driven by an electric motor 54 and actuated by movement of the push-pull cable 34 to thereby assist in causing steering movement of the motor in the direction urged by the push-pull cable 34. While the power assist means can have various constructions, in the illustrated arrangement, the support block 52 is supported for linear slidable movement on the tilt axis tube 24 between the arms 56 and 58 of the pivot bracket 22. Since the cable conduit 44 is fixed by means of the tube 51 to the support block 52, during actuation of the push-pull cable 34 wherein the cable core 42 and the rod 53 apply either a pushing or pulling force on the coupler 50, the conduit 44 and tube 51 will apply an equal and opposite force on the support block 52. 
     The means for providing power assisted steering also includes an elongated linearly extensible member 60 selectively driven by the electric motor 54. The elongated extensible member 60 includes one end connected to the coupler 50 and an opposite end which is secured against linear movement such that linear extension of the extensible member 60 will cause movement of the coupler 50 and the drag link 48 to effect pivotal steering movement of the outboard motor 10. While the elongated linearly extensible member 60 can have various configurations, in the illustrated arrangement, it includes a tube 62 having a threaded bore, the tube 62 being slidably supported in the pivot tube 24 for linear movement therein. One end of the tube 62 is connected to the coupler 50 and an opposite end of the tube 62 receives a threaded rod 64. The threaded rod 64 is journaled at its opposite end in a gear box 66 so as to be rotatably driven but restrained against axial movement. 
     Means are also provided for causing linear extension of the linearly extensible member 60 in the same direction as the movement of the cable core 42, and in response to movement of the cable core 42, to thereby provide power assisted movement of the coupler 50 and the drag link 48. As set forth above, the cable conduit 44 is fixed to the support block 52 which is in turn supported for slidable movement on the pivot tube 24. An input shaft 70 extends from the support block 52 so as to be freely rotatable with respect to the support block 52 but joined to the support block for movement with the support block 52 in the direction of the longitudinal axis of the pivot tube 24. A driven wheel 72 is fixed to the input shaft 70 intermediate its opposite ends. The electric motor 54 is continuously driven by a suitable source of electric power and includes an output shaft 74 extending perpendicularly to the axis of the input shaft 70, the output shaft 74 supporting a drive wheel 76 having a planar face 78 which engages the peripheral edge of the driven wheel 72. The input shaft 70 is connected in splined relation to a driven shaft 80 in such a manner as to rotatably drive the driven shaft 80 but also to be movable longitudinally with respect to the driven shaft. The driven shaft 80 is connected through the gears of the gear box 66 to the threaded rod 64 whereby rotation of the driven shaft 80 will result in rotation of the threaded rod 64 and with respect to the tube 62 to thereby cause linear extension of the threaded tube 62. It will be understood by those skilled in the art that various means (not shown) can be provided to support the electric motor 54 and the gear box 66. For example, they can be fixedly attached to the transom bracket 20 or to the transom 14. 
     In operation of the means for providing power assisted steering movement of the outboard motor, in a neutral position, i.e. wherein the outboard motor is stationary with respect to the steering axis, the support block 52 is positioned such that the driven wheel 72, supported by the input shaft 70, is positioned centrally on the planar face 78 of the drive wheel 76 whereby rotation of the drive wheel 76 does not impart rotation to the driven wheel 72. 
     Since the cable conduit 44 is fixed by the bracket 46, movement of the core 42 with respect to the conduit 44 adjacent the bracket 46 requires similar movement of the core 42 with respect to the conduit at the opposite end of the cable 34, thereby causing relative movement of the rod 53 and the support block 52, the rod 53 moving in one direction and the support block moving in an opposite direction. In the event the steering wheel 36 is rotated to thereby cause movement of the steering cable core 42 with respect to the conduit 44 such that the coupler 50 will tend to move right as seen in FIG. 1, the support block 52 will tend to move left. The resultant movement of the support block 52 causes the driven wheel 72 to shift to the left and away from the axis of the drive wheel 76. Rotation of the drive wheel 76 will then cause rotation of the driven wheel 72, and the consequent rotation of the input shaft 70 will be transmitted through the gear box 66 to cause rotation of the threaded rod 64 in such a direction as to cause longitudinal movement of the threaded tube 62 to the right, thereby assisting steering movement of the coupler 50. 
     If the steering wheel 36 is turned in the other direction, thereby causing movement of the core 42 to the left, the cable conduit 44 will cause movement of the driven wheel 72 to the right. Accordingly, the rotation of the drive wheel 76 will then cause rotation of the input shaft 70 in a direction causing linear movement of the threaded tube 62 to the left. 
     Various features of the invention are set forth in the following claims.