Composite modular self actuating variable pitch marine propeller

Abstract

This invention provides a composite modular self-actuating, variable pitch propeller with a cylindrical hub housing assembly, a plurality of blades that automatically adjust between an initial, fixed low pitch setting and multiple higher pitch settings that occur in response to centrifugal force, water pressure, spring tension and height adjustment of the upper section of the device and cam profile of the inner section of the blades and adjacent cam ramp on the hub. Also provided is an over hub exhaust design that allows engine exhaust to exit thru ports in the exterior wall of the hub section. Additionally, a threaded cap and spring in the top section provides a means of adjustment to limit the maximum high pitch. Finally, each blade includes a protruding cam profile perpendicular to the blade shaft axis, with a flat surface acting as a low pitch stop and a profile that extends upward.

We claim: 
     
         1 . A variable pitch marine propeller, made of ultra high strength durable plastic, comprising a modular hub housing of multiple sections, that is cylindrical in shape, with a circular opposing exterior shape encapsulating a plurality of blades thru multiple pockets in said housing, said blades extending outward radially from the housing pockets, with each blade rotating with and in the same direction as the housing, while being constrained within the housing to prevent ejection, while allowing for axial movement away from the center of the hub and pivotal rotation of the blades axially within the pockets, such rotation being caused by increasing propeller rotation velocity and water pressure on the blades, such rotation further allowing for changes in blade pitch from a fixed low pitch stop, this stop feature being incorporated axially, transversely outward from the blade shaft, along with a cam profile adjacent to said stop feature that allows for a structured increase in blade pitch change as the blade rotates further within said pocket and outwardly against an adjacent cam ramp on the hub, being controlled in structure by the contact movement of this cam profile against a moveable surface in a top section of the housing, said movement being further controlled in tension and limit by a compression spring and cap constraining said top section of the housing, further allowing entire propeller to be securely mounted axially from the housing to the rotating drive shaft of a boat, allowing the propeller to rotate with the drive shaft and incorporating within the lower section of the hub housing, side exit ports for an over hub exhaust system. 
     
     
         2 . The modular, variable pitch marine propeller of  claim 1 , further comprising a means of biasing the low pitch setting of all blades, such setting affecting all of the blades, causing all blades to remain biased and locked in a low pitch setting until the forces of the hub rotational velocity, centrifugal force and water pressure reach a point forcing all blades simultaneously to move off of the bias point to a higher pitch point, this initial bias setting accomplished by means of a flat surface extending outward, perpendicular to the blade shafts, internally within the encapsulating portion of the blade within the hub housing, said surface resting on an adjacent flat surface of the bottom section of the hub housing adjacent to the blade pockets. 
     
     
         3 . The modular, variable pitch marine propeller of  claim 2 , wherein the shafts of the blades contain a larger radiused diameter near the end opposite the blade surface that rotates axially with the blade upon an increase in pitch rotation need and is kept within the pocket by a corresponding larger diameter section of the pocket encapsulating the blade shaft. 
     
     
         4 . The modular, variable pitch marine propeller of  claim 2 , wherein the flat surface extending outward, perpendicular to the blade shaft adjoins a cam profile, said cam profile allowing for a controlled rotation of the blades upon sufficient force as previously described, to overcome the bias force being applied toward a lower pitch setting stop point, such rotation accomplishing a higher pitch setting of the blades, such pitch change made easier by the blade shafts being non centered and biased toward the posterior portion of the blades. 
     
     
         5 . The modular, variable pitch marine propeller of  claim 1 , wherein the upper section of the hub housing contains a flat surface under spring tension, that contacts the cam profile of all blades and applies spring force on the cam profiles with a natural tendency toward the bias low pitch setting flat stop point, said surface rising axially within the hub housing against an opposing compression spring, thus the more rise the more spring tension, thus along with the cam profile provides a controlled rise in blade pitch. 
     
     
         6 . The modular, variable pitch marine propeller of  claim 1 , wherein a middle section of the hub housing contains appropriately shaped openings, allowing the cam profiles of the blades to protrude through the bottom portion of the middle hub housing, allowing the bottom flat surface of the upper section of the hub housing to contact the cam profiles of the blades. 
     
     
         7 . The modular, variable pitch marine propeller of  claim 6 , wherein the upper portion of the middle section of the hub housing contains a hollow, threaded section, said threaded section allowing for a cap to be threaded onto it, securing the top movable section of the hub housing, said securing accomplished by means of a compression spring captured between the cap and a pocket within the upper movable section of the hub housing, the tension of the spring and the amount of threads engaged thus allowing for a set limit to the upward travel of the upper section of the hub housing, thus limiting the extent of high pitch setting on the cam and blade rotation and said hollow threaded section providing a flat surface within the hollow area with splined cuts allowing for the insertion of an off the shelf bronze splined insert that aligns with the splined surfaces of a boat motor shaft. 
     
     
         8 . The modular, variable pitch marine propeller of  claim 1 , wherein the lower section of the hub housing contains multiple hollow sections anterior to the blade pockets, said section having a cone shape aligned with the hub center axis, said shape decreasing in diameter toward the blade pocket area and exiting outward toward the upper portion of the lower section of the hub housing, thus providing an anterior over hub exhaust exit instead of the usual thru hub exhaust exit, said reduction in diameter allowing for an increase in air volume and decrease in back pressure from the exhaust gases exiting the boat motor. 
     
     
         9 . The modular, variable pitch marine propeller of  claim 8 , wherein the upper area of the lower section of the hub housing contains multiple half circle pockets, with larger radiused diameter areas closer to the center of the hub housing, where said pockets provide a means of encapsulating all the blade shafts, when assembled to the middle hub housing area these pockets align with similar half circle pockets in the middle section of the hub housing, making for complete circular pockets capturing all the blade shafts, said upper area also having a ramped protrusion off the top flat surface allowing for blade shaft protrusion contact for pitch change, as the blade shaft is forced to extend outward from the hub center and rotate up said ramp upon sufficient prop speed. 
     
     
         10 . The modular, variable pitch marine propeller of  claim 1 , wherein the lower and middle sections of the hub housing are cylindrical in shape and each section contains half of a circular opposing exterior extrusion, which when the sections are combined as is the intent of this invention, they provide a complete profile circularly that prevents interference between the outside walls of the hub housing and the posterior and anterior ends of all the blades when said blades rotate axially on their shafts for pitch change. 
     
     
         11 . The modular, variable pitch marine propeller of  claims 1 - 10 , whereby the two forces acting on the blades of centrifugal force and water pressure are able to act independently from one another non coupled, so that the blade shafts are allowed to travel axially outward from the hub center by centrifugal force and are forced to rotate upon such travel by contact between a ramped surface on the top flat surface of the hub bottom section and the cam profile protrusion protruding outward from the blade shaft, said action being independent of the shaft rotation occurring from increased water pressure behind the blades upon sufficient boat travel speed.