Patent Publication Number: US-10315748-B2

Title: Steering assembly for docking a marine vessel having at least three propulsion units

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to a steering assembly for docking a marine vessel and, in particular, to a steering assembly for docking a marine vessel with at least three propulsion units. 
     Description of the Related Art 
     In conventional marine steering systems, an operator may use a joystick to manoeuver and dock the marine vessel. The joystick allows the operator to manoeuver the marine vessel in a lateral direction, i.e. in a direction which is substantially perpendicular to a longitudinal axis of the marine vessel. This lateral directional movement is achieved by independently steering the propulsion units of the marine vessel to effect vector thrusting. For example, in a marine vessel provided with two propulsion units, shifting one of the propulsion units into reverse and simultaneously shifting the other propulsion unit into forward while selectively adjusting the steering angles of the propulsion units can cause the marine vessel to move in a lateral direction. The joystick controls both steering functions and shift and control functions during docking. Such conventional steering systems are also typically provided with a helm for steering the marine vessel on open water and a control lever for controlling shift and throttle functions on open water. An example of a conventional steering system is disclosed in PCT International Application Publication Number WO 2013/123208 A1. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide an improved steering system assembly for a marine vessel which has at least three propulsion units. 
     There is accordingly provided a steering system for a marine vessel having a first propulsion unit, a second propulsion unit, and a third propulsion unit. There is a hydraulic actuator for imparting steering motion to the first propulsion unit and a hydraulic actuator for imparting steering motion to the second propulsion unit. A tie bar couples a tiller of the third propulsion unit to the hydraulic actuator of the first propulsion unit. The tie bar imparts steering motion from the hydraulic actuator of the first propulsion unit to the tiller of the third propulsion unit. A joystick is used to input user steering commands to the steering system. Movement of the joystick actuates the said hydraulic actuators to impart steering motion to the first propulsion unit and the second propulsion unit. The third propulsion unit may be put in neutral when the joystick is used to input user steering commands. The third propulsion unit may also be trimmed up when the joystick is used to input user steering commands. Alternatively, the third propulsion unit may be turned off when the joystick is used to input user steering commands. 
    
    
     
       BRIEF DESCRIPTIONS OF DRAWINGS 
       The invention will be more readily understood from the following description of the embodiments thereof given, by way of example only, with reference to the accompanying drawings, in which: 
         FIG. 1  is a perspective view of a marine vessel provided with a plurality of propulsion units and an improved steering system; 
         FIG. 2  is a simplified top plan view of a joystick of the steering system of  FIG. 1  showing a guided plate inside the joystick and axes of movement of the joystick; 
         FIG. 3  is a perspective, fragmentary view of the propulsion units and the steering system of  FIG. 1  showing a center engine coupled to a starboard engine by a tie bar; 
         FIG. 4  is a table showing operating states of the propulsion units of the steering system of  FIG. 1 ; and 
         FIG. 5  is another table showing operating states of the propulsion units of the steering system of  FIG. 1 . 
     
    
    
     DESCRIPTIONS OF THE PREFERRED EMBODIMENTS 
     Referring to the drawings and first to  FIG. 1 , this shows a marine vessel  10  which is provided with a plurality of propulsion units in the form of three outboard engines, namely, a port engine  12 , a center engine  14 , and a starboard engine  16 . The marine vessel  10  is also provided with a control station  18  that supports a steering wheel  20  mounted on a helm  22 , a control head  24 , and a joystick  26 . The control station  18  is conventional and allows the port engine  12  and the starboard engine  16  to be steered using either the steering wheel  20  and the helm  22  or the joystick  26  as disclosed in PCT International Application Publication Number WO 2013/123208 A1 which is incorporated herein by reference. 
     When the marine vessel  10  is steered using the joystick  26 , and with reference to  FIG. 2 , movement of the joystick  26  along an X-axis moves the marine vessel  10  either starboard or port. Movement of the joystick  26  along a Y-axis moves the marine vessel  10  forward or in reverse. Movement of the joystick  26  along a θ-axis rotates the marine vessel  10  starboard or port. The joystick  26  is also moveable along the X-axis, Y-axis, and θ-axis to allow for vector thrusting. The joystick may further be used to provide any combination of partial or full X-axis, Y-axis and θ-axis commands. Movement of the joystick  26  as described above signals a pump control module  25 , shown in  FIG. 1 , which controls the output of hydraulic pumps  27  and  29  which respectively pump hydraulic fluid to hydraulic actuators  28  and  30 , shown in  FIG. 3 , of the port engine  12  and the starboard engine  16  based on the movement of the joystick  26 . Steering motion is thereby imparted by the hydraulic actuators  28  and  30  to corresponding ones of the port engine  12  and the starboard engine  16 . 
     However, the center engine  14  is not provided with a corresponding hydraulic actuator. Instead a tiller  32  of the center engine  14  is coupled to the hydraulic actuator  30  of the starboard engine  16  by a tie bar  34 . The tie bar  34  accordingly imparts steering motion from the hydraulic actuator  30  of the starboard engine  16  to the tiller  32  of the center engine  14 . When the marine vessel  10  is steered using the joystick  26 , the center engine  14  is put in neutral and may be trimmed up to reduce drag of the center engine  14  in the water as shown in  FIG. 4 . Trimming up the center engine  14  reduces the impact of the center engine  14  on marine vessel command performance when the joystick  26  is used to steer the port engine  12  and the starboard engine  16  during, for example, docking or other vector thrusting applications. Alternatively, the center engine  14  may be turned off and tilted out of the water as shown in  FIG. 5 . 
     Advantages of coupling the center engine  14  to the starboard engine  16  and putting the center engine  14  in neutral when using the joystick  26  to steer the marine vessel  10  may include: 
     reducing wear in the steering system which results from wagging of the center engine which occurs in conventional steering systems; 
     reducing performance issues found in conventional steering systems which result from conventional steering systems having to wait for the center engine to move before being able to steer the marine vessel in accordance with user inputted commands; 
     reducing the number of components and complexity of the steering system as it is not necessary to provide the center engine with a hydraulic actuator and related components; and 
     allowing for a center engine in situations where it is undesirable to provide the center engine with a hydraulic actuator due to physical constraints. 
     While the steering system disclosed herein will either put the center engine  14  in neutral or turn off the center engine  14  when the marine vessel  10  is steered using the joystick  26 , there are situations when the marine vessel  10  is steered using the joystick  26  in which it may be desirable to leave the center engine  14  in the water to assist marine vessel command performance. For example, it may be desirable to keep the center engine  14  in the water and in reverse if the starboard engine  16  is in reverse and the joystick  26  is being used to steer the marine vessel  10 . Due to the center engine  14  being in the water at the same angle as the starboard engine  16 , there may be a need for some asymmetry in the engine angle and/or engine thrust in the steering system to steer in one direction versus another. 
     It will be understood by a person skilled in the art that, in this example, the center engine is coupled to the starboard engine but that in other examples the center engine may be coupled to the port engine. 
     It will further be understood by a person skilled in the art that many of the details provided above are by way of example only, and are not intended to limit the scope of the invention which is to be determined with reference to the following claims.