Spring loaded geared flap rudder

A spring-loaded flap rudder adapted to be mounted to the hull structure of a ship. In a geared version of the invention, the rudder includes a rudder member and a rudder gear including rudder teeth. The rudder also includes a flap member pivotally connected to the rudder member with a spring and a movable flap gear. The flap gear includes a rod movably engaged in a socket of the flap member and gear teeth for engagement with the rudder teeth of the rudder gear.

BACKGROUND OF INVENTION

1. Field of the Invention

The present invention relates to marine craft. More particularly, the present invention relates to the rudders of marine craft. Still more particularly, the present invention relates to flap rudders.

2. Description of the Prior Art

A rudder in the form of a pivotable plate or a displacement body is disposed at the stern of a ship. When the rudder is actuated, it is pivoted by a controlled angle of deflection. That movement develops a hydrodynamic transverse force which acts on the rudder and correspondingly on the stern of the ship. This force produces the turning torque required to steer the ship. This hydrodynamic transverse force produces a torque on the rudder with respect to the rudder stock which is to be supplied by the steering gear.

There are single member rudders, flap rudders and geared flap rudders. The current basic arrangement for a geared flap rudder includes a rudder member with an associated fixed gear that engages with a flap member having an associated movable gear. The rudder member is oriented forward of the flap member when viewing the vessel bow to stern. The forward gear of the rudder member is joined to the hull and the aft gear of the flap member is joined to the flap member. As the rudder stock is turned, the flap angle is double the rudder angle. There are no sliding parts, no energy absorber and no bearings other than on the flap member to the rudder member. In another design, the rudder member includes a positively controlled fin that is deflected in opposition to the main rudder deflection without the aid of powered steering gear in order to establish torque equilibrium with respect to the rudder stock.

A limitation of the existing geared flap rudder design is experienced when the rudder member or the flap member is bent, such as may occur when either contacts large debris. If the bend is significant enough, it is not possible to move either or both of the rudder member and the flap member as desired to change their respective positions. That circumstance will compromise ship maneuverability. Another limitation of the existing geared flap rudder design occurs when debris, such as a log for example, wedges into the gearing, rendering it difficult or impossible to change the position of the gear. That too, will compromise the ability to maneuver the ship.

What is needed is a geared flap rudder that is configured to minimize the operation of the rudder when either or both of the rudder and the flap are impacted and bent. What is also needed is a geared flap rudder that is configured to avoid gear lockup resulting from debris getting into the gears that exist on the flap and the rudder. The geared flap rudder should remain functional for normal operations whether or not the flap, the rudder or the gears are compromised.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a spring-loaded flap rudder that is configured to minimize the operation of the rudder when either or both of the rudder and the flap are impacted and bent. It is also an object of the present invention to provide a spring-loaded geared flap rudder that is configured to avoid gear lockup resulting from debris getting into the gears that exist on the flap and the rudder. The geared flap rudder of the present invention remains functional for normal operations whether or not the flap, the rudder or the gears are compromised.

These and other objects are achieved with the present invention, which is a spring-loaded geared flap rudder. There is no other flap rudder available that is spring-loaded. The spring-loaded geared flap rudder of the present invention is substantially advantageous over any existing flap rudder. The spring is adjustable and so can be used to account for any misalignment of components of the flap rudder, including the gears of a geared flap rudder. That makes the present invention less costly to produce in addition to being less prone to jamming and deflections. Existing rudders must be manufactured and put together with tighter tolerances than is necessary with a spring-loaded flap rudder so that any problems of misalignment can be minimized.

The rudder joins the aft gear to a rod which fits into a cylinder and that cylinder is joined to the flap. At the aft end of the cylinder there is a spring. If the rudder stock is bent forward or aft, the spring deflects in or out to prevent jamming. If the rudder stock is bent to the side, the rod rotates in the cylinder and prevents jamming. This interface joins the flap and the moving gear together. The thickness of the gears can be made sufficient so that any relatively small branch, for example, that gets in the gear will be pulverized by the gear movement and any larger log will not fit between the gear teeth. The interface includes a cover plate that protects against items entering the gearing from above. The effective arm of the flap is constant, so that there is just as much force keeping the flap extended at 45 degrees as there is keeping it from wobbling at 0 degrees.

The invention is a spring-loaded rudder adapted to be mounted to the hull structure of a ship, the rudder comprising a rudder member including a rudder stock rotatably connectable to the hull structure, a rudder gear connectable to the hull structure, the rudder gear including rudder teeth, a flap member pivotally connected to the rudder member, wherein the flap member includes a socket and a flap gear including a rod movably engaged in the socket of the flap member and gear teeth for engagement with the rudder teeth of the rudder gear. The rudder includes a gear cover connectable to the hull structure and the rudder gear to cover the rudder teeth and the gear teeth. The rod of the flap gear is arranged for rotational and axial movement. The flap gear includes a spring positioned in the socket and arranged to enable axial movement of the rod of the flap gear. The flap member is pivotally connected to a trailing edge of the rudder member. The invention is, more generally, a spring-loaded flap rudder, whether or not the flap and rudder members include gears.

The introduction of the spring element within the cylinder at the flap gear to rudder gear interface ensures that the rudder remains operational when either is bent and when debris wedges into the gearing. This makes operation of the ship more certain and safer than is the case when existing geared flap rudders are used. These and other features and advantages of the present invention will be understood upon review of the following detailed description, the accompanying drawings and the appended claims.

DETAILED DESCRIPTION OF THE INVENTION

A spring-loaded geared flap rudder10of the present invention is shown inFIGS. 1-4. The flap rudder10includes a rudder member12, a flap member14, a rudder gear16, a flap gear18and a gear cover20. The flap rudder10is connected to a hull structure22of a ship aft of a propeller. Specifically, a rudder stock24of the rudder member12passes through a rudder port26of the hull structure22into an interior portion of the ship and joined to couplings and gearing controlled to cause movement of the rudder member12. The rudder member12to hull22interface is sealed, such as with a split-ring seal28, for example.

The rudder member12is rotatably mounted on the hull structure20by the rudder stock24such that the rudder member12is suspended from the hull structure22. The flap member14is pivotally mounted on a trailing edge30of the rudder member12by way of a pivot rod32.

The rudder gear16is connected to the hull structure22, such as by welding it in place. The rudder gear16remains fixed in position when either or both of the rudder member12and the flap member14move. The flap gear18is connected to the flap member14and is arranged to move with movement of either or both of the rudder member12and the flap member14. As shown inFIGS. 5-8, the flap member14and the flap gear18are separate components of the rudder10. The flap member14includes a socket34and a retaining bushing36at its leading edge. The flap member14further includes a component that permits axial movement of the flap gear18with respect to the socket34. For example, that member may be a spring38. The flap gear18includes a gear section40and a rod section42. The socket34, the bushing36and the rod section42are configured so that the rod section42fits into the socket34and is removably retained therein by the bushing36. When seated in position in the socket34, the rod42is adjacent to and in contact with a wear plate44spaced between the rod42and the spring38.

The rudder member12and the flap member14are joined together through the pivot rod32, the location of which establishes the spacing between those members. The flap member14moves with respect to the rudder member12by actuation of the pivot rod32and that movement is regulated by engagement of teeth46of the flap gear18with teeth48of the rudder gear16. While the rudder gear16remains in a fixed position, the flap gear18moves with movement of the flap member14, as can be seen in a comparison of the location of the teeth46with respect to the location of the teeth48shown inFIGS. 2 and 3.

The flap member14and the flap gear18combination permits continued functioning of the rudder10under conditions when either or both of the rudder member12and the flap member14are bent, torqued, twisted or otherwise less than completely aligned. That continued functioning is enabled because the rod42can rotate within the socket34so that the teeth46of the flap gear18will remain aligned with the teeth of the rudder gear16when the rudder member12and the flap member14are misaligned. In addition, the flap member14and the flap gear18combination permits continued functioning of the rudder10under conditions when debris gets into the gears. That continued functioning is enabled in that situation because the spring38will take up axial displacement of the flap gear18within the socket34until the debris is either crushed or passes out of the space between teeth46and teeth48. The rotational, compressive and elongate characteristics of the flap gear18maintain rudder10operation whether the rudder stock24bent sideways, fore or aft. The spring38has a spring value sufficient to keep the flap gear18in place when the rudder member12and the flap member14are properly aligned but will compress when needed. The compression in the spring38can be adjusted after the rudder10is in place to a value sufficient for the rudder10to operate as intended. Further, the inclusion of the spring38provides adjustability to correct misalignment of components of the rudder10including the rudder stock24, the fixed rudder gear16and the movable flap gear18. This is an advantage over existing flap rudders which must be built to relatively tighter tolerances to reduce the possibility of misalignment that may result in rudder limitations including failure.

The gear cover20is connected to the rudder gear16and to the hull structure22. It is located over the interface between the teeth46of the flap gear18and the teeth48of the rudder gear16. It is provided to minimize damage to the rudder10at that interface resulting from contact with debris or impact with a structure. As illustrated inFIG. 9, the rudder10remains operational with no jamming of the rudder gear16and the flap gear18even with a bent rudder member12that is shown in the figure as an example with the rudder member12about 15° out of alignment. Prior flap rudders would be incapacitated with such a bend of the rudder member.

The components of the rudder10of the present invention may be fabricated of one or more materials suitable for their intended functions in the environment of expected operation. For example, the rudder member12, the flap member14, the rudder gear16and the flap gear18may be fabricated of a metal such as steel, including stainless steel. The bushing36of the flap member18may be fabricated of metallic or nonmetallic material. For example, the bushing36may be a bushing available from Thordon Bearings, Inc., of Burlington, Ontario, Canada.

It is to be understood that various modifications may be made to the rudder described herein without departing from the spirit and scope of the invention. Accordingly, other embodiments are within the scope of the claims appended hereto.