Patent Abstract:
A device for cutting weeds carried by water inducted into a housing includes an intake, an outlet, an impeller for pumping water from the intake to the outlet as the impeller rotates about an axis, the impeller including a blade formed with a leading edge facing the intake, and a baffle secured against movement and including a cutting edge located adjacent the leading edge when the leading edge rotates to the location of the cutting edge.

Full Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates generally to an apparatus for a watercraft propelled by a water jet. In particular, the invention pertains to a device for cutting weeds and other debris contained in water inducted into the propulsion system. 
     2. Description of the Prior Art 
     A jet-boat is a boat propelled by a jet of water ejected from the back of the craft. Unlike a powerboat or motorboat that uses a propeller in the water behind the boat, a jet-boat draws the water from under the boat into a pump-jet inside the boat, then expels it through a nozzle at the stern. 
     Jet-boats are highly maneuverable, and can be reversed and brought to a stop within a short distance from full speed. 
     A conventional screw impeller accelerates a large volume of water by a small amount, similar to the way an airplane&#39;s propeller accelerates a large volume of air by a small amount. By contrast, an aircraft&#39;s jet engine accelerates a small volume of air by a large amount. In a jet-boat, pumping a small volume of water, accelerating it by a large amount, and expelling the water above the water line delivers thrust that propels the craft. The acceleration of the water is achieved by using an impeller. 
     Jet-boats normally plane across the water surface, with only the rear portion of the hull displacing any water. With the majority of the hull clear of the water, drag is reduced and maneuverability is enhanced. For stability, a jet-boat has a very shallow-angled hull. At speed, jet-boats can be safely operated in less than 12 inches (30 cm) of water. 
     Jet-boats are frequently operated in shallow fresh water where waterweeds flourish. These weeds grow in long strands that are often drawn into the water induction and propulsion system can become entangled with the impeller blades, shafts and ducting, and can clog the propulsion system. In extreme cases, the induction and propulsion system can become so filled with weeds and debris that the engine is stalled or water cannot be pumped at a rate that satisfactorily propels the craft. When this occurs, the craft must be removed from the water and the weeds removed manually. 
     There is a need in the industry for an effective, safe and reliable technique for cutting waterweeds and debris inducted into the propulsion system into lengths that are short enough to flow through the intake duct and impeller and out the nozzle without collecting there or impeding water flow through the propulsion system. 
     SUMMARY OF THE INVENTION 
     A device for cutting weeds carried by water inducted into a housing includes an intake, an outlet, an impeller for pumping water from the intake to the outlet as the impeller rotates about an axis, the impeller including a blade formed with a leading edge facing the intake, and a baffle secured against movement and including a cutting edge located adjacent the leading edge when the leading edge rotates to the location of the cutting edge. 
     The device has no moving parts, produces virtually no power loss, and is simple and effective. The baffle is easily mounted on the interior surface of the intake duct by a few conventional fasteners such as bolts or screws. The cutting edges formed on the baffle are spaced by a narrow gap from rotating edge of the rotating impeller blades, impeller hub and drive shaft such that weeds are chopped and cut into short lengths continually while engine power is transmitted to the impeller. 
     The scope of applicability of the preferred embodiment will become apparent from the following detailed description, claims and drawings. It should be understood, that the description and specific examples, although indicating preferred embodiments of the invention, are given by way of illustration only. Various changes and modifications to the described embodiments and examples will become apparent to those skilled in the art. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       The invention will be more readily understood by reference to the following description, taken with the accompanying drawings, in which: 
         FIG. 1  is a cross-sectional side view of a water induction system for use in a watercraft propelled by a jet stream. 
         FIG. 2  is cross-section taken at plane  2 - 2  of  FIG. 1 ; 
         FIG. 3  is a side view showing the impeller, baffle and motor shaft; 
         FIG. 4  is a front view of the sub-assembly shown in  FIG. 3 ; 
         FIG. 5  is a perspective view of the baffle; 
         FIG. 6  is a side view of the impeller; and 
         FIG. 7  is a side view of a jet powered kayak. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The water induction system  10  for propelling a boat with a water jet includes an intake duct  12 , a stator housing  14  secured to the trailing side of the intake duct by a series of annually spaced attachments  16 , such as bolts or screws, and a nozzle  18 , secured to the outlet end of the stator by a series of angularly spaced attachments  20 . Although the intake duct  12  is shown as a component separate from the hull of the component of the watercraft, it may be formed integrally with the hull. 
     The intake duct  12  is a shell, formed preferably of molded plastic having an intake  24 , through which water is inducted and flows toward an outlet  26  in the nozzle  18  along a path  22 . The intake duct  12  is formed with a cylindrical tube  28  that extends axially. A drive shaft  30 , which is splined to an engine shaft at  32 , extends through cylinder  28  and into an impeller  34 , to which the shaft is driveably connected. Shaft  32  extends through a hole  36  formed in the outer wall of intake duct  12 . The exit side of duct  12  is formed with a flange  38 , on which a series of angularly spaced bosses are formed and through which the attachment bolts  16  extend. 
     The streamline  22  represents the path and direction of flow of water from the inlet  24 , through intake duct  12 , impeller  34 , stator  14  and nozzle  18  to the outlet  26 . 
     Stator  14  encloses a cylindrical space containing the impeller  34 , and is formed with angularly spaced blades  46  and a cylinder  48  containing bearings  50 ,  52 , on which driveshaft  30  and impeller  34  are supported for rotation about axis  40 . Bearings  50  and  52  are protected by a seal  42  located in cylinder  48 , which prevents entry of water and contaminants into the angular space between shaft  30  and the bearings. 
     The intake side of stator  14  is formed with a flange  54  formed with attachment holes, which are aligned with holes in a flange  38  of the intake duct  12  and through which the attachment bolts  16  are inserted to connect the intake duct and stator  14 . Similarly, the outlet end of stator  14  is formed with a flange  56  formed with attachment holes, which are aligned with holes in a flange  64  of the nozzle  18  and through which the attachment bolts  20  are inserted to connect the stator and nozzle. 
     Nozzle  18  is preferably formed of molded plastic containing fins  60 , angularly spaced about axis  40  and aligned with the trailing edge of the blades  46  formed in the stator  14 . Supported on the outlet side of cylinder  48  is a cone  62 , which extends into the nozzle  18  and along which water flows to the outlet  26 . 
     A baffle  70 , preferably formed of stamped sheet metal, is secured by mechanical attachments located in holes  72  formed on fingers  74 , which extend laterally outward from a central plane  75  of the baffle. As  FIGS. 1 ,  3  and  4  show, baffle  70  includes at least three edges  76 ,  78 ,  80  formed on the periphery of plane  74 . Cutting edge  76  is located adjacent the leading edge of the blades  82  formed on impeller  34  when those blades rotate to the position of the baffle  70 , as shown in  FIG. 3 . Second cutting edge  78  is located adjacent the outer surface  81  of the impeller. Third cutting edge  80  is located adjacent the outer surface of driveshaft  30 . A narrow gap preferably having a width between about 2 mm. and 4 mm. separates the cutting edges  76 ,  78 ,  80  from the adjacent surface  81  of the impeller  34 , the leading edge of blades  78 , and the surface of driveshaft  30 , but the width of the gaps may be outside the range 2 mm. to 4 mm. 
     The blades  78  of impeller  34  comprise the three blades  84 ,  86 ,  88  shown in  FIG. 6 , which are secured to the outer surface  81  of hub  83  of impeller  34 . Each blade extends along and around the axis of the impeller as a helix. The axial end of each blade that is closest to the intake duct  12  is formed with a leading edge that extends outward from axis  40 , and the axial end of each blade that is closest to the nozzle  18  is formed with a trailing edge that extends outward from axis  40 . Blade  84  has a leading edge  90 ; blade  86  has a leading edge  92 , blade  86  has a leading edge  94 . Blades  84 ,  86 ,  88  extend angularly about axis  40 ; therefore the blades overlap when viewed axially as in  FIG. 4 . The trailing edge  96  of blade  86  and the trailing edge  98  of blade  84  appear in  FIG. 6 . 
     Although the leading edges  90 ,  92 ,  94  of the impeller blades  84 ,  86 ,  88  are shown as straight in  FIG. 4 , they may be curved, and the cutting edge  76  may also be curved to conform to the shape of the leading edges. Although the impeller is shown with three blades, it may have four or more blades. 
     In operation, weeds and other debris carried by water from the intake  24  through the intake duct  12  to the entrance of the impeller  34  are cut or chopped into short lengths by the cutting edges  76 ,  78   82  formed on baffle  70 . The leading edges  90 ,  92   94  of the respective impeller blades  84 ,  86 ,  88  pass close to the cutting edge  76  of baffle  70  as the impeller blades rotates about axis  40 , thereby drawing weeds and debris entrained in the water to the cutting edges, where they are cut into short lengths as each impeller blade rotates past the cutting edge  76 . Similarly, the outer surface  81  of the impeller  34  and the outer surface of shaft  30  draw weeds and debris to the second and third cutting edges  78 ,  80 , where the weeds are cut into short lengths. After the weeds are cut into short lengths in this manner, the short weed lengths are carried in the water at high speed through the impeller  34 , stator  14  and nozzle  18 , exit through the outlet  26 , and return to the water on which the watercraft is floating. 
       FIG. 7  shows the drive shaft  30 , water intake duct  12 , intake passageway  24 , stator  14 , baffle  70 , impeller  34 , nozzle  18  and outlet  26  installed in a jet-powered kayak  100 . The water jet  102 , which propels and steers the craft is seen rising from the nozzle&#39;s outlet  26  into the air above the water surface. An engine, located at the left-hand end of drive shaft  30 , drives impeller  34 , whose blades draw water into the system and force water in a high velocity jet  102  from the system. 
     In accordance with the provisions of the patent statutes, the preferred embodiment has been described. However, it should be noted that the alternate embodiments can be practiced otherwise than as specifically illustrated and described.

Technology Classification (CPC): 1