Fixed mount electric actuator for marine steering system, and propulsion unit comprising the same

Abstract

According to at least one embodiment, an electric actuator for a marine steering system is disclosed. The electric actuator includes a housing, an output shaft, a screw assembly coupled to the output shaft, a rotor coupled to the screw assembly, and a motor configured to rotate the rotor. Rotation of the rotor causes the output shaft to translate axially relative to the housing.

What is claimed is: 
     
         1 . An electric actuator for a marine steering system, the electric actuator comprising: 
 a housing;   an output shaft;   a screw assembly coupled to the output shaft;   a rotor coupled to the screw assembly; and   a motor configured to rotate the rotor, wherein rotation of the rotor causes the output shaft to translate axially relative to the housing.   
     
     
         2 . The electric actuator of  claim 1  wherein the output shaft is fully received within the housing. 
     
     
         3 . The electric actuator of  claim 1  wherein the output shaft includes a coupling portion, the coupling portion fully received within the housing and coupleable to a tiller of a propulsion unit. 
     
     
         4 . The electric actuator of  claim 3  wherein the coupling portion is between first and second ends of the output shaft. 
     
     
         5 . The electric actuator of  claim 3  wherein the coupling portion is at an end of the output shaft. 
     
     
         6 . In combination, the electric actuator of  claim 3  and the tiller, wherein the tiller is coupled to the coupling portion. 
     
     
         7 . The combination of  claim 6  wherein the tiller has a tiller axis and is coupled to the coupling portion such that a line of action of the output shaft is in the same plane as the tiller axis throughout the entire steering range. 
     
     
         8 . The combination of  claim 6  wherein the tiller has a tiller axis and is coupled to the coupling portion such that an axis of the output shaft intersects the tiller axis through the entire steering range. 
     
     
         9 . The electric actuator of  claim 1  wherein the rotor has an axial bore which engages with the screw assembly. 
     
     
         10 . The electric actuator of  claim 9  wherein the screw assembly comprises a drive screw, the drive screw coupled to the output shaft. 
     
     
         11 . The electric actuator of  claim 9  wherein the screw assembly is a roller screw assembly comprising a plurality of rollers and a central screw received by the rollers, the rollers being rotatable about the central screw and the central screw coupled to the output shaft, wherein the axial bore engages with the rollers of the roller screw assembly. 
     
     
         12 . The electric actuator of  claim 1  wherein the output shaft has an axial bore which engages with the screw assembly. 
     
     
         13 . The electric actuator of  claim 12  wherein the screw assembly is a roller screw assembly comprising a plurality of rollers and a central screw received by the rollers, the rollers being rotatable about the central screw and the central screw coupled to the rotor, wherein the axial bore engages with the rollers of the roller screw assembly. 
     
     
         14 . The electric actuator of  claim 1  wherein rotation of the rotor causes the screw assembly to translate axially relative to the rotor. 
     
     
         15 . The electric actuator of  claim 1  wherein the screw assembly is axially stationary relative to the housing. 
     
     
         16 . The electric actuator of  claim 1  wherein the screw assembly engages the rotor directly. 
     
     
         17 . The electric actuator of  claim 1  wherein the screw assembly engages the output shaft directly. 
     
     
         18 . The electric actuator of  claim 1  wherein the motor is concentric to the screw assembly. 
     
     
         19 . The electric actuator of  claim 1  wherein the motor includes a stator and the rotor. 
     
     
         20 . The electric actuator of  claim 1  wherein the motor includes a stator and a motor shaft, the motor is configured to rotate the motor shaft, and the motor shaft is rotationally coupled to the rotor such that rotation of the motor shaft applies a torque to the rotor to cause rotation of the rotor. 
     
     
         21 . A propulsion unit comprising:
 the electric actuator of  claim 1 , wherein the output shaft includes a coupling portion; and   a tiller coupled to the coupling portion.   
     
     
         22 . The propulsion unit of  claim 21  wherein the coupling portion is fully received within the housing.