Outboard motor steering assembly with rudder reference sensor
An outboard motor having a steering control and a rudder reference sensor, both connectible to a computer-operated guidance system. The steering control utilizes a linear actuator connected through a linkage to the motor. The actuator utilizes a rack that moves along the axis about which the motor pivots from its use position to its storage position, thereby enabling the rudder position sensor to remain connected to the motor when the motor is pivoted from its use position to its storage position. The sensor can include a follower disposed in a sloping groove on the rack, a pin on the rack engaged in a helical groove on a cylinder, or an externally mounted sensor connected to the steering linkage through an auxiliary linkage.
1. An electrically operated outboard motor steering assembly comprising:
an outboard motor comprising an engine, a rudder fixed to the engine, and a propeller driven by the engine, the outboard motor being pivotable about a horizontal axis from a use position in which its rudder and propeller are submerged to a storage position in which its rudder and propeller are out of the water, and pivotable about a steering axis substantially perpendicular to a plane in which the horizontal axis lies;
a steering control comprising an actuator linked to the outboard motor, and having an elongated actuator element movable linearly, within a range of movement, along an actuator axis substantially aligned with said horizontal axis;
a rudder reference sensor providing a unique electrical signal for each rotational position of the outboard motor about the steering axis; and
a guidance system connected to receive the electrical signal provided by the rudder reference sensor, and connected to operate the actuator to rotate the outboard motor about the steering axis so that the outboard motor maintains a position corresponding to a predetermined heading;
wherein the rudder reference sensor is connected to the actuator both when the outboard motor is in its use position and when the outboard motor is in its storage position;
wherein said rudder reference sensor comprises a potentiometer having a fixed part and a movable part, and in which a resistance setting of the potentiometer varies depending on relative positions of said fixed and movable parts; and
wherein the steering assembly also includes a cam mechanism comprising a first cam element connected to and movable linearly with said actuator element as said actuator element moves linearly along said actuator axis, and a second cam element continuously engaged with the first cam element, and connected to move said movable part of the potentiometer, whereby the potentiometer has a unique resistance setting for each actuator position within said range.
2. An electrically operated outboard motor steering assembly according to claim 1 , in which said first cam element is an elongated contact surface extending along the elongated actuator element, in which a distance from said contact surface to the actuator axis varies along a length of the actuator element, and in which the second cam element comprises a follower engaged with and movable by said contact surface in a direction transverse to a direction of the actuator axis.
3. An electrically operated outboard motor steering assembly according to claim 1 , in which the movable part of the potentiometer is a potentiometer shaft rotatable about a potentiometer axis extending substantially parallel to said actuator axis, in which said first cam element is an elongated cylindrical member extending along the potentiometer axis and connected to the potentiometer shaft and rotatable therewith, said cylindrical member having a helical groove, and in which the second cam member is a pin fixed to said actuator element and extending into said helical groove, whereby axial movement of the pin effects rotation of the cylindrical member, and a rotational position of the cylindrical member varies depending on an axial position of said actuator element.
4. An electrically operated outboard motor steering assembly according to claim 1 , including a potentiometer housing, and in which the movable part of the potentiometer is a potentiometer shaft rotatable about a potentiometer axis, and the fixed part of the potentiometer is releasably held in said housing, and rotatable about said potentiometer axis when released, for adjustment of a relationship of said resistance setting of the potentiometer to an axial position of said actuator element.