Tractor pump jet

A single-stage tractor pump jet marine propulsion apparatus comprising

• A) mounting bracket adapted to be mounted on the transom of a water borne vehicle, and
• B) an outboard propulsion unit including
• 1) an upper gear case assembly mounted on the mounting bracket for pivotal movement about a generally horizontal tilt axis and about a generally vertical steering axis, the gear case assembly having a lower end,
• 2) a generally vertical drive shaft which is driven by a power head and which extends downwardly through the gear case assembly, and
• 3) a lower unit including
• a) a support strut connected to the lower end of the gear case assembly by a plurality of bolts, the support strut having a lower end, and
• b) a pump jet housing connected to the lower end of the support strut, the pump jet housing being adapted to be submerged in open water and being externally streamlined for minimum drag losses in the water and maximum marine propulsion efficiency, the pump jet housing including
• (i) a rotor housing having forward and rearward ends and a generally horizontal central axis, the forward end of the rotor housing defining an inlet opening, such that there is no intake conduit upstream of the inlet opening, the inlet opening being circular and having a cross-sectional area, the inlet opening being centered on the central axis and being located in a generally vertical plane, and
• (ii) a stator housing having forward and rearward ends and a central axis coaxial with the central axis of the rotor housing, the forward end of the stator housing being connected to the rearward end of the rotor housing, the rearward end of the stator housing defining an outlet opening having a cross-sectional area, the area of the inlet opening being greater than the area of the outlet opening,
• c) a stator hub surrounded by the stator housing, the stator hub having an interior and an exterior, the drive shaft extending through the stator housing and into the interior of the stator hub,
• d) a plurality of stator vanes extending outwardly from the stator hub and connecting the stator hub to the stator housing,
• e) a closure plate fixed to the forward end of the stator hub to close the interior of the stator hub,
• f) a rotor shaft having forward and rearward ends and extending along the central axis of the stator housing, the rotor shaft extending through the closure plate and being rotatably supported by the closure plate, the rearward end of the rotor shaft extending into the interior of the stator hub and being rotatably supported by the stator hub, the forward end of the rotor shaft extending forwardly of the stator hub,
• g) a pinion gear fixed to the lower end of the drive shaft within the interior of the stator hub,
• h) a forward-drive crown gear mounted on the rotor shaft within the interior of the stator hub, the crown gear meshing with the pinion gear such that rotation of the drive shaft causes rotation of the rotor shaft in a forward-drive direction when the crown gear is engaged with the rotor shaft,
• i) an axial flow pump rotor mounted on the forward end of the rotor shaft for rotation therewith, the rotor being located within the rotor housing, immediately rearward of the inlet opening, and forward of the stator hub, the rotor having a diameter and including a hub mounted on the rotor shaft, and a plurality of blades, each of the blades having an inner end connected to the rotor hub, an outer edge, a leading edge forming a sharp corner with the outer edge, a trailing edge forming a sharp corner with the outer edge, and a width between the leading and trailing edges, the width changing from the inner end to the outer edge, such that the width is greatest at the outer edge, the outer edges of the blades defining a cylinder centered on the rotor shaft, the distance from the inlet opening to the rotor being less than one-half the diameter of the rotor,
• j) a nose cover covering the forward end of the rotor shaft, the nose cover extending forwardly of the inlet opening, and
• k) a plurality of inlet struts extending outwardly from the nose cover and connecting the nose cover to the rotor housing,
• the stator housing, the rotor housing, the stator hub and the rotor hub defining, inside the stator housing and the rotor housing and outside of the stator hub and the rotor hub, a flow passage which extends between the inlet opening and the outlet opening, which has a crosssectional area along the length thereof, which contains the rotor, and through which captured inlet water flows, the crosssectional area of the passage changing such that the crosssectional area of the passage is smallest at the outlet opening, the stator housing and the rotor housing being externally streamlined for minimum drag losses in the water and for maximum marine propulsion efficiency, the interior of the stator housing and the rotor housing and the exterior of the stator hub and the rotor hub contacting the captured inlet water and being streamlined for minimum turbulence, minimum flow separation and minimum hydrodynamic losses and for maximum marine propulsion efficiency, the inlet struts providing structural integrity and minimization of turbulence of captured inlet water, the location of the rotor immediately rearward of the inlet opening and forward of the stator hub causing the rotor to operate on relatively undisturbed water.

Marine apparatus comprising

• a water borne vehicle including a hull, the hull having a bottom and a transom, and
• a tractor pump jet including
• a power head positioned inside the vehicle,
• a mounting bracket mounted on the transom of the water borne vehicle,
• an upper gear case assembly extending from the mounting bracket, and
• an outboard propulsion unit mounted on the gear case assembly, the propulsion unit having upper and lower ends and including a generally vertical drive shaft which is driven by the power head and which extends downwardly through the propulsion unit, a pump jet housing at the lower end of the propulsion unit, the pump jet housing being located completely below the bottom of the hull, being adapted to be submerged in open water and being externally streamlined for minimum drag losses in the water and maximum marine propulsion efficiency, the pump jet housing having an interior, a generally horizontal central axis and forward and rearward ends, the forward end of the pump jet housing defining an inlet opening, such that there is no intake conduit upstream of the inlet opening, the inlet opening having a cross-sectional area, and the rearward end of the pump jet housing defining an outlet opening having a cross-sectional area less than the area of the inlet opening, the outlet opening being totally submerged when the vehicle is operating in water, the drive shaft extending into the interior of the pump jet housing, a rotor shaft extending along the central axis of the pump jet housing, the lower end of the drive shaft being drivingly connected to the rotor shaft, and an axial flow pump rotor mounted on the rotor shaft for rotation therewith, the rotor being located within the pump jet housing, immediately rearward of the inlet opening, and forward of the lower end of the drive shaft, the pump jet housing defining a flow passage which extends between the inlet opening and the outlet opening, which contains the rotor, and through which captured inlet water flows, the interior of the pump jet housing contacting the captured inlet water and being streamlined for minimum turbulence, minimum flow separation and minimum hydrodynamic losses and for maximum marine propulsion efficiency, the location of the rotor immediately rearward of the inlet opening and forward of the drive shaft causing the rotor to operate on relatively undisturbed water.

Marine apparatus comprising

• a water borne vehicle including a hull, the hull having a bottom and a transom, and
• a single-stage tractor pump jet including
• a mounting bracket mounted on the transom of the water borne vehicle, and
• an outboard propulsion unit including
• an upper gear case mounted on the mounting bracket for pivotal movement about a generally horizontal tilt axis and about a generally vertical steering axis, the gear case having a lower end,
• a generally vertical drive shaft which is driven by a power head and which extends downwardly through the mid-section, and
• a lower unit including
• a support strut connected to the lower end of the gear case by a plurality of bolts, the support strut having a lower end, and
• a pump jet housing connected to the lower end of the support strut, the pump jet housing being located completely below the bottom of the hull, being adapted to be submerged in open water and being externally streamlined for minimum drag losses in the water and maximum marine propulsion efficiency, the pump jet housing including
• a rotor housing having forward and rearward ends and a generally horizontal central axis, the forward end of the rotor housing defining an inlet opening, such that there is no intake conduit upstream of the inlet opening, the inlet opening being circular and having a cross-sectional area, the inlet opening being centered on the central axis and being located in a generally vertical plane,
• a stator housing having forward and rearward ends and a central axis coaxial with the central axis of the rotor housing, the forward end of the stator housing being connected to the rearward end of the rotor housing, the rearward end of the stator housing defining an outlet opening having a cross-sectional area, the outlet opening being totally submerged when the vehicle is operating in water, the area of the inlet opening being greater than the area of the outlet opening,
• a stator hub surrounded by the stator housing, the stator hub having an interior and an exterior, the drive shaft extending through the stator housing and into the interior of the stator hub,
• a plurality of stator vanes extending outwardly from the stator hub and connecting the stator hub to the stator housing,
• a closure plate fixed to the forward end of the stator hub to close the interior of the stator hub,
• a rotor shaft having forward and rearward ends and extending along the central axis of the stator housing, the rotor shaft extending through the closure plate and being rotatably supported by the closure plate, the rearward end of the rotor shaft extending into the interior of the stator hub and being rotatably supported by the stator hub, the forward end of the rotor shaft extending forwardly of the stator hub,
• a pinion gear fixed to the lower end of the drive shaft within the interior of the stator hub,
• a crown gear mounted on the rotor shaft within the interior of the stator hub, the crown gear meshing with the pinion gear such that rotation of the drive shaft causes rotation of the rotor shaft,
• an axial flow pump rotor mounted on the forward end of the rotor shaft for rotation therewith, the rotor being located within the rotor housing, immediately rearward of the inlet opening, and forward of the stator hub, the rotor having a diameter and including a hub mounted on the rotor shaft, and a plurality of blades, each of the blades having an inner end connected to the rotor hub, an outer edge, a leading edge forming a sharp corner with the outer edge, a trailing edge forming a sharp corner with the outer edge, and a width between the leading and trailing edges, the width changing from the inner end to the outer edge, such that the width is greatest at the outer edge, the outer edges of the blades defining a cylinder centered on the rotor shaft, the distance from the inlet opening to the rotor being less than one-half the diameter of the rotor,
• a nose cover covering the forward end of the rotor shaft, the nose cover extending forwardly of the inlet opening, and
• a plurality of inlet struts extending outwardly from the nose cover and connecting the nose cover to the rotor housing,
• the stator housing, the rotor housing, the stator hub and the rotor hub defining, inside the stator housing and the rotor housing and outside of the stator hub and the rotor hub, a flow passage which extends between the inlet opening and the outlet opening, which has a crosssectional area along the length thereof, which contains the rotor, and through which captured inlet water flows, the crosssectional area of the passage changing such that the crosssectional area of the passage is smallest at the outlet opening, the stator housing and the rotor housing being externally streamlined for minimum drag losses in the water and for maximum marine propulsion efficiency, the interior of the stator housing and the rotor housing and the exterior of the stator hub and the rotor hub contacting the captured inlet water and being streamlined for minimum turbulence, minimum flow separation and minimum hydrodynamic losses and for maximum marine propulsion efficiency, the inlet struts providing structural integrity and minimization of turbulence of captured inlet water, the location of the rotor immediately rearward of the inlet opening and forward of the stator hub causing the rotor to operate on relatively undisturbed water.