Outboard motor steering system

Abstract

An outboard motor steering system wherein an electric motor is installed inside the outboard motor and the output of the electric motor rotates a swivel shaft to steer the propeller, thereby enhancing steering feel by using an electric motor to enable highly responsive and accurate control. In addition, the configuration is simple and does not lead to an increase in number of components or weight. In another steering system wherein a first hydraulic cylinder for driving a steering system and second hydraulic cylinders for driving a power tilt-trim system are supplied hydraulic oil from the same pump, thereby making a dedicated hydraulic pump for the steering system unnecessary and thus enabling reduction of system size and weight. In still another steering system wherein the outboard motor main unit is swiveled to turn the propeller by extension/contraction of the hydraulic cylinder whose one end is attached to the outboard motor main unit and other end is attached to the boat side of the outboard motor. In a plan view taken in the gravitational direction, moreover, the hydraulic cylinder is located inside the vertical projection plane of the profile of the outboard motor main unit, so that the hydraulic cylinder never projects outside the outboard motor main unit no matter how much it extends or contracts.

1 : A steering system for an outboard motor mounted on a stern of a boat and having an internal combustion engine at its upper portion and a propeller with a rudder at its lower portion that is powered by the engine to propel the boat, comprising: 
 a swivel shaft connected to the propeller to turn the propeller relative to the boat; and    an electric motor installed inside the outboard motor and connected to the swivel shaft to rotate the swivel shaft such that the propeller is turned by rotation of the electric motor.    
   
   
       2 : A steering system according to  claim 1 , wherein the swivel shaft is rotatably accommodated inside a swivel case and the electric motor is fixed at an upper portion of the swivel case to rotate the swivel shaft.  
   
   
       3 : A steering system according to  claim 2 , wherein the electric motor is connected to a mount frame that is connected to the swivel shaft in such a manner that the electric motor rotates the mount frame through a gearbox similarly fixed inside the outboard motor so as to turn the propeller.  
   
   
       4 : A steering system according to  claim 3 , wherein the gearbox includes gears which mesh with a mount frame gear to transmit the rotation of the electric motor to the mount frame such that the propeller is turned by the rotation of the electric motor.  
   
   
       5 : A steering system according to  claim 4 , wherein the mount frame gear is formed on an arcuate end face of the mount frame.  
   
   
       6 : A steering system according to  claim 1 , wherein the swivel shaft is rotatably accommodated inside a swivel case and the electric motor is fixed at a lower portion of the swivel case to rotate the swivel shaft.  
   
   
       7 : A steering system according to  claim 2 , wherein the electric motor is connected to a lower mount center housing that is connected to the swivel shaft in such a manner that the electric motor rotates the lower mount center housing through a gear so as to turn the propeller.  
   
   
       8 : A steering system according to  claim 7 , wherein the gear includes an electric motor output shaft gear which meshes with a lower mount center housing gear to transmit the rotation of the electric motor to the lower mount center housing such that the propeller is turned by the rotation of the electric motor.  
   
   
       9 : A steering system according to  claim 8 , wherein the lower mount center housing gear is formed on an arcuate end face of the lower mount center housing.  
   
   
       10 : A steering system according to  claim 1 , further including: 
 a cable connecting the electric motor and the swivel shaft;    and wherein the rotation of electric motor is transmitted to the swivel shaft through the cable such that the propeller is turned by the rotation of the electric motor.    
   
   
       11 : A steering system according to  claim 10 , further including; 
 a gear fastened on an output shaft of the electric motor;    a gear fastened on the swivel shaft; and    a holder equipped on the cable to be meshed with the gears;    and wherein the rotation of electric motor is transmitted to the swivel shaft through the holder of the cable and the gears such that the propeller is turned by rotation of the electric motor.    
   
   
       12 - 17  (canceled)