Long shaft propeller controller and bearing seal protector

Abstract

A marine propulsion system for shallow waters, swamps, savannahs and the like includes a rotating propeller shaft supporting a propeller. An anti-cavitation body defines a partial cylinder having a longitudinal axis adjacent to the propeller. The propeller generates a vacuum between the anti-cavitation body and a surface of a water body. First and second wings adjacent to edges of the anti-cavitation body are generally planar and operatively angled towards the bottom of a water body. The first and second wings are adjusted to run below the water body surface and seal the anti-cavitation body to maintain generated vacuum. A first thread is cut in a first helical direction at an end of the rotating propeller shaft adjacent the propeller, and slightly more distal therefrom a second thread is cut in a second helical direction opposed to the first thread helical direction. The second thread drives matter away from the bearing.

Claims

1. A long shaft propeller, comprising: a power source; a rotary drive shaft coupled to said power source at a first end and having a first helical thread formed in a first direction of rotation adjacent a second end distal to said power source and a second helical thread formed in a second direction of rotation opposed to said first direction of rotation adjacent to said first helical thread and spaced by said first helical thread from said shaft second end; a casing surrounding said rotary drive shaft; at least one bearing adapted to separate said rotary drive shaft from said casing; a propeller; a housing about said at least one bearing attached to said casing at a first end and having a first opening adjacent said casing and a second opening distal to said first opening; at least one shaft seal adjacent said second opening; a removable housing cover enclosing said second opening and removable therefrom, said removable housing cover having a bore that non-frictionally circumscribes said second helical thread therein.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The foregoing and other objects, advantages, and novel features of the present invention can be understood and appreciated by reference to the following detailed description of the invention, taken in conjunction with the accompanying drawings, in which:

(2) FIG. 1 illustrates a preferred embodiment long shaft propeller designed in accord with the teachings of the present invention from a projected view.

(3) FIG. 2 illustrates a preferred embodiment cavitation plate designed in accord with the teachings of the present invention and illustrated in the preferred embodiment long shaft propeller of FIG. 1, from a top plan view.

(4) FIG. 3 illustrates the preferred embodiment cavitation plate of FIG. 2 from a side elevation view.

(5) FIG. 4 illustrates the preferred embodiment cavitation plate of FIG. 2 from a rear elevation view.

(6) FIG. 5 illustrates the coupling of the preferred embodiment cavitation plate of FIG. 2 into the preferred embodiment long shaft propeller of FIG. 1, as well as the preferred embodiment propeller bearing seal protector, by a partial section view taken along line 5 of FIG. 1.

(7) FIG. 6 illustrates the preferred embodiment propeller bearing seal protector and bearing housing of FIG. 5 from an exploded view.

(8) FIG. 7 illustrates the preferred embodiment long shaft propeller of FIG. 1 from a rear elevation view.

DESCRIPTION OF THE PREFERRED EMBODIMENT

(9) Manifested in the preferred embodiment, the present invention provides a long shaft propeller that tracks to the surface of the water, and that further provides an extended seal and bearing life, thereby reducing the need for service or likelihood of failure during use.

(10) A preferred embodiment long shaft propeller 1 is illustrated in FIG. 1. A transom mount 12 or suitable equivalent will most preferably be provided for coupling to a water craft such as a flat bottom boat or the like. A source of motive power 2, which will be known to those in the art to include such devices as internal combustion engines, electric motors and other known motive power sources is operatively connected through appropriate linkage, commonly including a universal joint, fasteners and other suitable couplers known in the art, and for exemplary purposes enclosed in safety shield 13, to propeller shaft 70 (visible in FIGS. 5 and 6). Shaft 70 passes through casing 8 to propeller 20. A framework 3 is preferably provided, though not essential to the invention, which adds structural integrity to casing 8 while only adding a minimum of mass. In the preferred embodiment long shaft propeller 1, this framework 3 is comprised of three legs 4-6 and optional cross-members 7, each which are preferably manufactured from hollow tubular material for optimum strength with minimal weight. Handle 9 is most preferably also manufactured from hollow tubular material that may be swaged or otherwise deformed or otherwise rendered capable of being coupled with legs 5 and 6, preferably by insertion into an open end of either leg 5 or leg 6. Some operators prefer to always use only one hand for directing propeller 20, and they will also prefer to sit on a particular side of the handle. By making handle 9 attachable with and removable from either leg 5 or leg 6, a particular operator may customize the placement of handle 9 within a boat to accommodate this preference. Additionally, and while not illustrated, it will be understood that a mechanical or electronic motor throttle, choke or control may be provided, such as but not limited to a hand control provided through a mechanical linkage or cable adjacent the operator end of handle 9.

(11) Adjacent propeller 20, a rudder-like plate or skeg 10 serves to both assist in directional control and also to protect propeller 20 from impact with submerged objects or entanglement. The gentle and continuous slope 15 assists in less-forceful lifting of propeller 20 over any submerged objects. A steeper trailing edge 16 is designed to more forcefully push weeds, string, or other matter that may be sliding along slope 15 to be shifted down and away from the rotating propeller 20, preferably enough in advance of propeller 20 to prevent the debris or weeds from being contacted by propeller 20. However, the transition between slope 15 and trailing edge 16 is preferably sufficiently smooth and continuous to prevent the debris or weeds from becoming attached thereto.

(12) Over the top of, and immediately adjacent to propeller 20 is a uniquely configured cavitation plate 30, illustrated in additional detail in FIGS. 2-5 and 7. Cavitation plate 30 has a generally tear-drop geometry from the top plan view of FIG. 2. An oval cut-out 34 is provided that is most preferably shaped to engage at an angle with casing 8, and preferably produce inconsequential drag therewith. Gentle tapering edges 35, like the gentle slope 15 on skeg 10, helps to guide propeller 20 smoothly and less forcefully around obstacles, while also preventing weeds, string or other matter from becoming affixed. An arcuate anti-cavitation body 31, defining a partial cylinder which may preferably have a center of radius approximately aligned with the axis of rotation of propeller 20, and which is also preferably only slightly larger in diameter than propeller 20, serves to contain water thereunder between anti-cavitation body 31 and propeller 20, develop a vacuum with the water surface tending to keep propeller 20 at the desired height typically partially above the average level of the relatively adjacent water surface, and also shields propeller 20.

(13) The arcuate shape of anti-cavitation body 31 ends along two longitudinally extending edges adjacent transition 36, and wings 32 and 33 extend therefrom. Wings 32 and 33 each preferably have a separate center of radius that is both substantially offset sideways from the anti-cavitation body 31 center of radius, and also is preferably of a much larger radius than that of anti-cavitation body 31. In fact, wings 32 and 33 are generally planar, with only a very slight curvature.

(14) The only sharp or discontinuous transition in cavitation plate 30 occurs at transition 36, which is at the tail end of wings 32, 33 and which allows anti-cavitation body 31 to extend into tail region 37 as much farther as desired or needed for proper operation. In the preferred embodiment, optional slots 38 are provided through which fasteners 14, visible in FIG. 5, may pass. Also visible in FIG. 5, a mounting support 11 for cavitation plate 30 is provided that is rigidly affixed to casing 8. A set of holes are provided therein, also through which fasteners 14 will pass. Consequently, cavitation plate 30 can be removably attached to mounting support 11. To accommodate different propellers, casings, and frameworks, an adjusting shim 17 may also be provided to permit small angular adjustments to be made between cavitation plate 30 and casing 8.

(15) In operation, a relatively powerful vacuum is formed under anti-cavitation body 31, measured for exemplary purposes in one embodiment of the present invention at 5 inches, or 13 centimeters, of mercury. Wings 32, 33 operatively interact with and are submerged by the water, while anti-cavitation body 31 is primarily above the average water level. This means that a substantial force is created that draws cavitation plate 30 downward to the water surface, and thereby reduces the need for an operator to manually try to maintain a propeller level within the water. One of the functions of wings 32, 33 is to help maintain the seal against the water, even when small waves or surface ripples pass cavitation plate 30.

(16) While the invention is not limited to the following theory of operation, and so no limitations are inferred as a consequence thereof, the dimensions of generally planar wings 32, 33 and the angular adjustment with casing 8 are each selected to provide sufficient drag in the water that, if they become submerged too far, they will force sufficient water down to lift propeller 20. If instead propeller 20 lifts to try to rise out of the water, these wings 32 and 33 may begin to catch water and pull propeller 20 downward. In addition, anti-cavitation body 31 is reacting with propeller 20, to generate a vacuum when anti-cavitation body 31 rises out of the water. This prevents propeller 20 from continuing upward and popping out of the water. As should be understood, this combination of anti-cavitation body 31, which forms a partial circumference of a tube, and wings 32, 33 which seal vacuum under anti-cavitation body 31 and which directly react with the water, form a very complex interaction between the body of water and cavitation plate 30. When the angle of cavitation plate 30 is properly set with adjusting shim 17 or by other equivalent permanent or adjustable means, propeller 20 will be constrained to stay immediately adjacent to and partially above the normal level for the water body. Consequently, there is reduced interference with shallow bottoms, sand bars, and submerged obstacles compared to a prior art long shaft propeller. Further, the consequential forces generated by cavitation plate 30 allow an operator to steer the boat by pivoting long shaft propeller 1 about a vertical axis, without significant concern for also manually controlling the depth of propeller 20, which is rotation about a horizontal axis. Instead, cavitation plate 30 acts as the depth controller, relieving both the need for attention and physical exertion. Additionally, cavitation plate 30 improves the efficiency of propeller 20, producing more propulsion than without cavitation plate 30, even when propeller 20 without cavitation plate 30 is run at deeper levels within the water body. FIGS. 5 and 6 include illustrations of a preferred bearing, bearing seal protector, and propeller coupling. At the end of casing 8 adjacent propeller 20 is a sealed bearing unit 40 that in the preferred embodiment provides ball-bearing support for propeller shaft 70 within casing 8, thereby minimizing friction while improving the life and reliability of long shaft propeller 1. Sealed bearing unit 40 is illustrated by exploded view in FIG. 6 and partial cross-section in FIG. 5, and includes a bearing housing 46 threaded onto a threaded nose 42 which is designed to be rigidly affixed to casing 8. A rubber O-ring or equivalent seal 44 is preferably provided there between.

(17) Most preferably, the interior of bearing housing 46 defines a bearing compartment that will be sufficiently large that bearings 48-52 may contain not only a bearing, but also be provided with inner and outer bearing races. This is most preferred, since the construction of bearings is a precise art where small deviations are known to have adverse affects upon the performance of the bearings. Furthermore, special materials and treatments are required, the processes which are highly refined in the production of reliable bearings. These processes are used in high volume in the production of bearings, thereby adding little to the total cost of the bearing. However, to incorporate this level of precision and processing into the present bearing unit 40 would add undesirably to the cost, and, absent the full technology used in the bearing industry, would also lead undesirably to lower production yields and greater failures during use.

(18) Once bearings 48-52 are inserted within bearing housing 46, shaft seals 56, 58 are inserted. These seals 56, 58 may for exemplary purposes be elastomeric, and will engage with and seal shaft 70. Seals 56, 58 may also optionally include grease or the like, not only for lubrication, but also for the water repellent nature of grease and oil. Through either or both grease or other hydrophobic matter and shaft seals 56, 58, no water should penetrate into bearing housing 46. Threads will engage cover 62 with bearing housing 46, and may solely be used as the final seal against water intrusion into bearing housing 46. However, it is also contemplated to provide an elastomeric seal 60, which may be a washer or O-ring, between cover 62 and bearing housing 46. One or more small surface indentations 64, which do not pass entirely through cover 62, may be provided to receive a spanner wrench-like tool that enables cover 62 to more easily be turned relative to bearing housing 46.

(19) Unfortunately, even with the best of seals 56, 58, foreign material such as fine sand, thread, string or other matter may migrate into these seals 56, 58. In such case, the rotation of shaft 70 will rapidly lead to wear and failure of seals 56, 58, exposing the bearings directly to water and similar fine sand, thread, string and the like. Consequently, bearings 48-52 are more prone to failure after seals 56, 58 have failed.

(20) To protect bearing seals 56, 58, and as best viewed in FIGS. 5 and 6, cover 62 has a bore 65, visible in FIG. 5, that non-frictionally accommodates threads 72 therein. Threads 72 are threaded oppositely to threads 74. As illustrated in FIG. 5, shaft 70 will rotate when viewed from the end with threads 74 in a counter-clockwise fashion. This means that threads 74, which are cut in a clock-wise manner, will tend to push any sand, debris, string, weeds, or any other matter up shaft 70 towards bearing seals 56, 58. Most undesirably, this action by threads 74, if left unaltered, can greatly accelerate the failure of seals 56, 58.

(21) The present invention overcomes this limitation of the prior art by providing opposed threads 72, 74. In the preferred embodiment, threads 74 are cut in a clockwise manner. Consequently, threads 72 will be cut in a counter-clockwise manner. This means that any string, debris or other matter will be pushed by threads 72 away from seals 56, 58. A close tolerance between bore 65 and threads 72 will improve the efficiency of threads 72, but there needs to be sufficient space there between to accommodate tolerances, minor shaft flexure and the like as well. Furthermore, if so desired, a softer or resilient sleeve might be provided to fill any space between bore 65 and threads 72, such that if there were an event that caused relative movement between bore 65 and threads 72, only the sleeve would be destroyed. Further, such a sleeve could be designed to be removable and replaceable, again if so desired.

(22) Relatively close tolerance between bore 65 and threads 72 has other important benefit. When debris, a rock, other obstacle or the like is hit by propeller 20, in the prior art this would commonly bend shaft 70 within seals 56, 58. A bend at that location would cause aggressive wear and rapidly tear or otherwise destroy seals 56, 58. Furthermore, the vibration from the bent shaft would also cause much greater bearing wear. However, when there is only a small gap between bore 65 and threads 72, preferably sufficiently small that non-yielding flexure in shaft 70 will close or bridge the gap, then in the event of an impact, shaft 70 will be bent and threads 72 will contact the lip of bore 65 most adjacent to propeller 20. When threads 72 contact bore 65, then cover 62 acts as additional shaft reinforcement, effectively stiffening shaft 70 and in most cases avoiding permanently deforming shaft 70. In the event of an impact still sufficiently powerful to permanently deform shaft 70 even with the stiffening provided by cover 62, cover 62 moves the bend away from the bearings and seals, and more nearly adjacent to the propeller. This not only helps to permit the boat to still be propelled back to dock or shore, even if at a reduced speed, but also simplifies repair or straightening.

(23) Threads 74 are used to hold propeller 20, and an internally threaded split nut 23, having a cylindrical exterior, is preferably used to rigidly locate propellor 20 on one face. On the opposed face, a washer, small tube 22 or the like may be provided, in turn locked into place by nut 21. Split nut 23 has a cylindrical exterior that ensures no disruption of water flowing into propeller 20, and the smooth surface also reduces the likelihood that weeds and other debris will tangle and remain thereon. As known in the hardware art, a split nut is completely split through one radial cut, and the cut may be closed with a threaded bolt or the like. 180 degrees removed from the complete split is preferably a partial cut terminated with a round hole or the like. This allows the two halves of the split nut to flex and move away from each other similar to shackles or hand cuffs, facilitating the removal of split nut 23 from threads 74, while also avoiding turbulence and weed entanglement. As best visible in FIG. 6, thread 72 may be cut in shaft 70 at the full diameter of shaft 70, and may be cut all the way from the end of shaft 70. Next, shaft 70 may optionally be turned or otherwise machined to remove threads 72 completely in the region of shaft 70 ultimately intended to receive threads 74. Otherwise, a suitable thread cutting die may fabricated and used that simply cuts thread 74 deep enough to remove any remnants of threads 72. In the process of forming threads 74, shaft 70 in this region of threads 74 is smaller in diameter than in the region of thread 72 or in the unthreaded region. An additional benefit is obtained from this. Since propellor 20 is ultimately supported on threads 74, in the event of a major and damaging impact, shaft 70 will be slightly stronger in the unthreaded region than in threads 72, and threads 72 are slightly stronger than threads 74. Consequently, in the event of as damaging overload, shaft 70 will preferentially bend either in threads 74 or at the juncture between threads 74 and threads 72. The change in diameter will be selected at the time of design, but with a larger change in diameter better protecting the unthreaded region of shaft 70 from harm.

(24) Another advantage comes from the use of the present housing 46. In use, when a bearing fails, the failure often times destroys the bearing but less frequently damages shaft 70 or bearing housing 46. Consequently, only bearings 48-52 will need replacement, and, as long as relatively common bearings are used for bearings 48-52, these bearings may be obtained from bearing supply sources, hardware dealers and the like which are located in most small towns throughout the world. The exact type of bearing used is not critical to the invention, and different types including ball and roller bearings are contemplated herein. Nevertheless, while less preferred, it is also contemplated herein to use bearings such as needle bearings and the like which do not include outer races, and which would therefore consume less space, and instead use bearing housing 46 as the outer race. Using bearings without a race provides a size advantage, since, without bearing races, bearing housing 46 may be made with a much smaller outside diameter more closely resembling or even the same as casing 8.

(25) Three bearings 48-52 are most preferred, owing to the affects of bending within shaft 70 during operation, particularly when an obstacle is encountered. When shaft 70 is flexed out of being exactly coaxial with bearing housing 46, a force is applied radially in a first direction against bearing 48 and radially in an opposite direction against bearing 52, while bearing 50 will operate essentially in balance and serve as a point of pivot for shaft 70. The benefit is the lack of twisting forces applied to a single bearing, thereby enhancing the overall life of the bearing structure. Furthermore, the total load supported by the three bearings 48-52 is, of course, distributed across all three bearings. While it may be possible to manufacture a bearing structure having only one or two bearings therein, it is less preferred.

(26) Bearing housing 46 and cover 62 may be machined from carbon steel, stainless-steel or other suitable material. The exact material is not critical to the performance of the invention, provided there is sufficient strength to withstand the forces of impact that may occur during use, as well as the forces which occur during general use, and sufficient corrosion resistance to withstand the intended marine application. The geometries illustrated are all cylindrical, which allows bearing housing 46 and cover 62 to each be manufactured through reasonably low-cost turning and drilling procedures.

(27) In use, shaft 70 passes through the center of bearing housing 46 into the center of ball bearings 48-52, where shaft 70 is radially supported. In the event bearings 48-52 should seize and rotate relative to housing 46, housing 46 may be damaged. Nevertheless, should this occur housing 46 may then be removed and replaced. While a local source may not be available, the overnight shipping charges for bearing housing 46 are substantially lower than for a full casing 8. Similarly, in the event casing 8 should be damaged and unuseable, only casing 8 must be replaced and not bearing housing 46. Likewise, should shaft 70 be the only damaged component, then only shaft 70 will need replaced.

(28) In the event one or more bearings 48-52 fail without damaging bearing housing 46, bearing housing 46 may be removed from casing 8 and shaft 70, and then cover 62 and seals 56, 58 are removed. Finally, a punch, screw-driver or the like may be used to press axially against the side of any bearing 48-52, to press the bearings 48-52 out of bearing housing 46. The ability to remove bearing housing 46 from casing 8 allows better access to bearings 48-52. Other techniques known in the bearing arts may be provided to assist with the removal of bearings.

(29) While bearing housing 46 is most preferably removable from casing 8, it is conceivable that bearing housing 46 could be manufactured to be an integral part thereof. In this case, access to bearings 48-52 may be somewhat more difficult. Regardless of whether removable or integral, bearing housing 46 will still preferably present an outer surface which most closely resembles the outer surface of casing 8. When the turbulence becomes too great, or when bearing housing 46 has too great a protrusion from casing 8, water will spray up into the air when propeller 20 is operated in shallow water. This is very undesirable.

(30) While the foregoing details what is felt to be the preferred embodiment of the invention, no material limitations to the scope of the claimed invention are intended. Further, features and design alternatives that would be obvious to one of ordinary skill in the art are considered to be incorporated herein. For example, while a strong and corrosion resistant material such as stainless, coated or otherwise treated steel is described as preferable for manufacturing, alternative materials such as ABS plastic and the like are also contemplated. These and other materials might also be produced using different manufacturing techniques as well, such as molding or casting. The scope of the invention is set forth and particularly described in the claims herein below.