Abstract:
A propeller attachment is disclosed including a body, the body including an anodic material, at least one projection projecting from the body, and a fastener coupled to the body. An anode is also disclosed including an annular body constructed from an anodic material, a fastener disposed centrally in the annular body, and at least one extension coupled to the annular body, the at least one extension is configured to allow for gripping of the anode. A fastener for coupling a propeller to a drive shaft of a lower unit is disclosed including a fastening portion configured to threadably engage the drive shaft and retain the propeller. The fastener further includes an anodic portion disposed around the fastening portion. The anodic portion is shaped to form at least one grip, and the anodic portion preferentially corrodes to prevent corrosion of the lower unit.

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to the field of anodes. Specifically, the present invention relates to the field of anodes for use on submersible motors, propellers and the like. 
     BACKGROUND OF THE INVENTION 
     Certain materials (typically metals, and metal alloys) corrode (i.e. rust, pit, deteriorate, etc.) due to various corrosive phenomena. Such corrosive phenomena may include electrochemical corrosion such as galvanic corrosion. Galvanic corrosion occurs when dissimilar materials are in contact with each other, and an electrical circuit is completed. Often, electrolytic solutions complete the electrical connection which causes galvanic corrosion. Electrolytic solutions, which provide mobile charge carriers for the conduction of electrical current, are often provided by water, such as salt water, pond water, or other such solutions. 
     When dissimilar metals are in contact with each other in a “galvanic series,” the more anodic material (i.e. the material with a higher tendency to sacrifice electrons in a galvanic series) will preferentially sacrifice electrons for the less anodic (or more cathodic) material. The electrons which are sacrificed for the cathodic material result in the corrosion or deterioration of the anodic material. Higher carrier mobility in the electrolytic solution may result in an enhanced or accelerated corrosion rate of the anodic material. Anodic materials may corrode at an enhanced or accelerated rate when submerged in electrolytic solutions such as water, including salt water, fresh water, etc. 
     It is know to provide an additional sacrificial anode, with higher anodic characteristics than the dissimilar materials which are to be protected, in electrical communication with the dissimilar materials, in order to inhibit or slow the rate of corrosion of the dissimilar materials. However, such sacrificial anodes are not well suited for use on submersible motors, propellers, lower units, and the like. Submersible motors, propellers, and lower units are often constructed from dissimilar materials, and submersed in an electrolytic solution such as pond water, lake water, salt water, etc. Due to this combination, the motors, propellers, and lower units may have an enhanced or accelerated rate of corrosion. Such arrangements often require the use of sacrificial anodes to slow or prevent corrosion. 
     However, typical sacrificial anodes often require multiple assembly steps to install the anode in the desired location. Furthermore, typical sacrificial anodes are not integral to the motor, propeller or lower unit, and may be difficult to install. Also, installing sacrificial anodes often requires compromising the body with invasive procedures such as drilling, tapping, etc. 
     Accordingly, it would be advantageous to provide an anode which would be integral to the design of the motor, propeller, or lower unit. It would also be advantageous to provide an anode with a design which minimizes the number of parts required, and reduces the cost of construction. Also, it would be advantageous to provide an anode which could be provided on a motor, propeller, or lower unit without additional assembly steps. It would further be advantageous to provide an anode which is easy to remove and replace. Furthermore, it would be advantageous to provide an anode which may be mounted without compromising the unit or body. It would also be advantageous to provide an anode which offers an integral construction. 
     It would be desirable to provide a propeller assembly which provides one or more of these advantageous features. The techniques below extend to those embodiments which fall within the scope of the appended claims, regardless of whether they provide one or more of the above-mentioned advantageous features. 
     SUMMARY OF THE INVENTION 
     According to one exemplary embodiment, a propeller attachment includes a body, the body including an anodic material, at least one projection projecting from the body, and a fastener coupled to the body. 
     According to another exemplary embodiment, an anode includes an annular body constructed from an anodic material, a fastener disposed centrally in the annular body, and at least one extension coupled to the annular body, the at least one extension is configured to allow for gripping of the anode. 
     According to another exemplary embodiment, a fastener for coupling a propeller to a drive shaft of a lower unit includes a fastening portion configured to threadably engage the drive shaft and retain the propeller. The fastener further includes an anodic portion disposed around the fastening portion. The anodic portion is shaped to form at least one grip, and the anodic portion preferentially corrodes to prevent corrosion of the lower unit. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of an anode assembly according to an exemplary embodiment; 
     FIG. 2 is an exploded perspective view of the anode assembly; 
     FIG. 3 is a side elevation view of the anode assembly; 
     FIG. 4 is a cross-section view of the anode assembly shown in FIG. 1, taken along the line  4 — 4 ; 
     FIG. 5 is an exploded perspective view of an anode portion and a fastening portion according to an exemplary embodiment; 
     FIG. 6 is a perspective view of the anode portion shown in FIG. 5; 
     FIG. 7 is a front elevation view of the anode portion shown in FIG. 5; 
     FIG. 8 is a top plan view of the anode portion shown in FIG. 5; 
     FIG. 9 is a cross-section view of the anode portion shown in FIG. 6, taken along the line  9 — 9 ; 
     FIG. 10 is a perspective view of an anode portion according to an alternative embodiment; and 
     FIG. 11 is a perspective view of an anode assembly according to an alternative embodiment. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to FIG. 1, an anode assembly  10  is shown on a lower unit  12  of a trolling motor  14 . It should be noted at the outset that anode assembly  10  may be used on a variety of structures and assemblies which require anodic protection. For example, anode assembly  10  may be used on various submersible propellers such as outboard motor propellers, submersible pumps, shaft driven devices which may be subjected to corrosive effects, etc. 
     As shown in FIG. 2, anode assembly  10  includes anode portion  16  and fastening portion  18 . In an exemplary embodiment, anode portion  16  includes body  20 , aperture  22  and projections  24 . As shown in FIG. 7, body  20  may have an annular or ring shape. Body  20  is generally constructed from a suitable anodic material. In an exemplary embodiment, body  20  includes lead, iron, cadmium, copper, aluminum, and zinc. In a particularly preferred embodiment, body  20  is constructed from 0.006% lead, 0.005% iron, 0.025-0.070% cadmium, 0.005% copper, 0.1-0.5% aluminum, and the remainder of zinc. According to another particularly preferred embodiment, body  20  is constructed from at most 0.006% lead, at most 0.005% iron, at most 0.025-0.070% cadmium, at (most 0.005% copper, at most 0.1-0.5% aluminum, and the remainder of zinc. Alternatively, body  20  may further include, or be constructed from magnesium, lithium, titanium, manganese, chromium, nickel, tin, and/or other suitable anodic materials. 
     As shown in FIG. 6, aperture  22  is provided in the center of body  20 . Aperture  22  generally has a shape corresponding to a fastening portion  18 , as will be discussed in further detail below. Alternatively, the body may have other shapes and geometries, and the aperture may be provided in different locations as to allow the proper functioning of, mounting, and attachment of the anode assembly. 
     Anode portion  16  further includes projections  24 . Projections  24  are provided on, and extend from body  20 . In an exemplary embodiment shown in FIG. 6, body  20  lies generally in a plane formed with horizontal axis X—X and vertical axis Y—Y. Projections  24  extend out of the plane formed generally by body  20 . As shown in FIG. 8, projections  24  extend normal to body  20 , along depth axis Z—Z. In an alternative embodiment shown in FIG. 10, anode portion  116  includes projections  124  which may be coplanar with body  120 , extending radially therefrom. The projections may be tabs, ears, extensions, grips, or other similar type features which provide for grasping of the body (and corresponding anode assembly). The projections advantageously provide a feature or structure which allows the anode assembly to be easily installed or removed by hand, or with simple tools such as pliers, screw drivers, wrenches, etc. 
     Referring to FIG. 5, fastening portion  18  is coupled to anode portion  16 . In an exemplary embodiment, fastening portion  18  is a fastener shown as nut  26 . In a preferred embodiment, nut  26  is a standard sized hexagonal fastening nut. Nut  26  may be coupled to body  20  by press-fitting nut  26  into aperture  22 . Alternatively, the nut may be coupled to the body by a variety of fastening techniques including soldering, welding, adhesives, etc. In an alternative embodiment shown in FIG. 11, anode assembly  210  may be a unitary construction, with the anode portion  216  and the fastening portion  218  being constructed as a unitary piece by techniques such as co-molding or similar processes. 
     The functioning, operation, and installation of anode assembly  10  will be described below. 
     In an exemplary embodiment shown in FIG. 1, anode assembly  10  may be used on submersible motors, such as those used in boats and water craft including outboard motors, inboard motors, trolling motors, etc. Anode assembly  10  may be used to secure or fasten a propeller  28  to a drive shaft  30  on such a motor, shown as lower unit  12  of a trolling motor  14 . 
     Shaft  30  may be provided with a fastener (shown as threaded portion  34 ) which is configured to engage a threaded portion  34  on nut  26 . Propeller  28  is slid onto shaft  30  through an aperture (not shown) in the center of propeller  28 . A spacer or retainer (shown as washer  36 ) may then be provided on shaft  30 . Anode assembly  10  is then fastened on to threaded portion  34  of shaft  30 . As anode assembly is tightened, nut  26  further engages threaded portion  34  of shaft  30 , and bears down on washer  36  and firmly retains propeller  28  with respect to shaft  30 . 
     Propeller  28  on lower unit  12  of trolling motor  14  may generally be constructed of plastic, and therefore will not be subjected to corrosive phenomena. However, several components in lower unit  12  are made of materials which may corrode. Such materials generally are metallic, such as steel, steel alloys, aluminum, aluminum alloys, or other such metals which may corrode. 
     Lower unit  12  will often be constructed from a variety of dissimilar materials for various design concerns. For example, a housing  32  of lower unit  12  may be constructed from an aluminum alloy for weight concerns, while drive shaft  30  and various other motor components may be constructed from steel for strength or other design concerns. 
     Contact between two dissimilar metals (such as aluminum and steel) in an electrolytic solution may create an electrochemical cell which may cause electrochemical corrosion. Metals in such an electrochemical cell will tend to be either anodic or cathodic, and create a “galvanic series.” A galvanic series is a rating of the materials according to their anodic or cathodic tendencies. An anodic material will tend to give up electrons in the electrochemical cell and corrode, while a cathodic material will tend to receive electrons in the electrochemical cell, and not corrode. 
     Referring to FIG. 2, anode assembly  10  is shown attaching propeller  28  to shaft  30  of lower unit  12 . Lower unit  12  of trolling motor  14  includes an outer shell or casing, shown as housing  32  surrounding shaft  30 . Housing  32  may typically be constructed from an aluminum or aluminum alloy. Lower unit  12  of trolling motor  14  may further include an electric motor (not shown) contained within housing  32 . The electric motor will power shaft  30  in rotation, and thus power the rotation of propeller  28  through water. The electric motor and shaft  30  may include steel or steel alloys. 
     Thus in lower unit  12 , the contact of aluminum housing  32  and steel drive shaft  30  in an electrolytic solution (i.e. water, salt water, etc.) will create an electrochemical cell, and will promote the corrosion of the more anodic material (i.e. aluminum housing  32 ). In order to prevent the corrosion of the anodic material in the galvanic series, a sacrificial anode (i.e. anode assembly  10 ) may be provided. The anode material of anode assembly  10  will have an even higher anodic potential than aluminum housing  32 , and thus will preferentially corrode instead of aluminum housing  32 . 
     Anode assembly  10  provides several advantages for the anodic protection of lower unit  12 . Anode assembly  10  provides a design which is integral to the design of lower unit  12 , and used to retain propeller  28 , not an additional part needed to be assembled onto lower unit  12 . The integral design advantageously provides for lowered assembly costs by reducing the number of parts required to be assembled. The integral design also allows anode assembly  10  to be used on lower unit  12  without additional, possibly invasive, attachment steps such as drilling or tapping. Additionally, anode assembly  10  provides a design which is easy to remove and replace. Projections  24  on anode assembly  10  allow anode assembly  10  to be easily removed by hand, or with tools such as a screw drive, pliers, wrench, or other common tools. Additionally, projections  24  advantageously offer an additional volume of sacrificial anodic material, thus prolonging the expected life of anode assembly  10 . 
     It is also important to note that the construction and arrangement of the elements of the anode assembly shown in the preferred and other exemplary embodiments is illustrative only. Although only a few embodiments of the present inventions have been described in detail in this disclosure, those skilled in the art who review this disclosure will readily appreciate that many modifications are possible (e.g., variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters, mounting arrangements, use of materials, colors, orientations, etc.) without materially departing from the novel teachings and advantages of the subject matter recited in the claims. Accordingly, all such modifications are intended to be included within the scope of the present invention as defined in the appended claims. The order or sequence of any process or method steps may be varied or re-sequenced according to alternative embodiments. In the claims, any means-plus-function clause is intended to cover the structures described herein as performing the recited function and not only structural equivalents but also equivalent structures. Other substitutions, modifications, changes and omissions may be made in the design, operating conditions and arrangement of the preferred and other exemplary embodiments without departing from the scope of the present inventions as expressed in the appended claims.