A volute pump for delivering a liquid containing fibrous substances. The volute pump includes an impeller (1) rotatable together with a rotational shaft (11), and an impeller casing (5) having a suction port (3) and a volute chamber (7). A groove (18), extending from the suction port (3) to the volute chamber (7), is formed in an inner surface of the impeller casing (5). The impeller (1) includes a hub (13) to which the rotational shaft (11) is fixed, and a sweep-back vane (2) extending helically from the hub (13). The sweep-back vane (2) includes a leading edge portion (2a) extending helically from the hub (13), and a trailing edge portion (2b) extending helically from the leading edge portion (2a). The leading edge portion (2a) has a front-side curved surface (2e) extending from an inner end (2c) to an outer end (2d) of the leading edge portion (2a).

A vessel propulsion apparatus includes a propulsive force generator including a duct and a propeller. The duct includes a stator. The propeller includes a rim that includes a rotor disposed at a position facing the stator, and a blade on an inner side in a radial direction of the rim. The vessel propulsion apparatus further includes a steering shaft that turnably supports the duct, a motor controller that rotationally drives an electric motor including the stator and the propeller in forward and reverse rotation directions, a turning mechanism that turns the duct in a full turning angle range including a range of 180 degrees, and a turning angle range limiter that limits a turning angle range of the turning mechanism to a reduced turning angle range narrower than the full turning angle range, and when a predetermined limitation cancellation condition is met, cancels the limitation and allows turning in a turning angle range wider than the reduced turning angle range.

A vessel propulsion apparatus includes a propulsive force generator including a duct and a propeller. The duct includes a stator. The propeller includes a rim that includes a rotor disposed at a position facing the stator, and a blade on an inner side in a radial direction of the rim. The vessel propulsion apparatus further includes a steering shaft that turnably supports the duct, a motor controller that rotationally drives an electric motor including the stator and the propeller in forward and reverse rotation directions, a turning mechanism that turns the duct in a full turning angle range including a range of 180 degrees, and a turning angle range limiter that limits a turning angle range of the turning mechanism to a reduced turning angle range narrower than the full turning angle range, and when a predetermined limitation cancellation condition is met, cancels the limitation and allows turning in a turning angle range wider than the reduced turning angle range.

A method and device is provided for increasing the efficiency of jet drives by recuperating effective power from the propulsion flow. A ducted propeller in the propeller housing, driven by a driving engine via a drive shaft, conveys the fluid for the jet drive out of the interior V.sub.i of a radial turbine . The fluid is accelerated axially and ejected backwards against the direction of travel. This creates thrust. Because the pressure in the interior of the turbine decreases, new fluid from the environment flows directly via the blades of the rotating radial turbine from the outside to the inside, thereby driving them. A guide apparatus is missing. The power of the radial turbine is transmitted via a transmission to the drive shaft of the propeller, which relieves the driving engine and increases the efficiency of the jet drive. The invention is particularly suitable for electric drives.

A marine propulsion unit includes a duct including a stator, a propeller including a rim including a rotor disposed at a position that faces the stator and a blade provided radially inward of the rim, a steering shaft that supports the duct such that the duct is steerable, a casing provided separately from the steering shaft and that extends along a rotation axis of the propeller, and a motor controller disposed in the casing and configured or programmed to control rotational driving of the propeller.

A marine propulsion unit includes a duct including a stator, a propeller including a rim including a rotor disposed at a position that faces the stator and a blade provided radially inward of the rim, a steering shaft that supports the duct such that the duct is steerable, a casing provided separately from the steering shaft and that extends along a rotation axis of the propeller, and a motor controller disposed in the casing and configured or programmed to control rotational driving of the propeller.

A fan system includes a rotor having plurality of blades and a ring airfoil, the plurality of blades being rotatably joined to a hub and the ring airfoil. The fan system may include a second contra-rotationally disposed rotor having a plurality of blades and a ring airfoil. The first and second ring airfoils having a cambered shape and an angle of attack between about 5 degrees and about 45 degrees, more preferably between about 5 degrees and about 30 degrees. Optionally, an outlet guide vane may be mounted rearward of the one or more rotors having a ring airfoil.

A fan system includes a rotor having plurality of blades and a ring airfoil, the plurality of blades being rotatably joined to a hub and the ring airfoil. The fan system may include a second contra-rotationally disposed rotor having a plurality of blades and a ring airfoil. The first and second ring airfoils having a cambered shape and an angle of attack between about 5 degrees and about 45 degrees, more preferably between about 5 degrees and about 30 degrees. Optionally, an outlet guide vane may be mounted rearward of the one or more rotors having a ring airfoil.

This new art offers six add on motorized attachments for the benefit of the recent trend of hydro foil surfing wherein said wave hydro foils comprise a mast attached to the bottom side of a surfboard and a fuselage that has a large forward lifting wing and a small aft stabilizing wing and is able to lift a 250 lb man and surfboard approximately two feet above the water surface at slow paddling speeds riding a wave from underneath the water surface wherein said new art enables said hydrofoil surfboard to motor along on flat water at high speeds cruising or fielding for waves then said new art can retract a motorized structure completely out of the water while in motion to allow a surfer to catch then foil ride a wave or an ocean swell without power by means of two types of retractable motorized apparatus wherein the first type has a vertical strut that holds a propeller and cort nozzle in a down position motoring forward wherein said strut can retract horizontally up and out from the water surface wherein this retractable strut type can embody three similar versions. Also the second type has a torpedo shaped fuselage that contains a motor, a propeller and cort nozzle also embodying three similar versions that can travel up the foil mast stopping at said surfboard's bottom surface with the power shut off allowing the remaining under water foil apparatus to glide and free ride a wave or swell as it was designed to.

This new art offers six add on motorized attachments for the benefit of the recent trend of hydro foil surfing wherein said wave hydro foils comprise a mast attached to the bottom side of a surfboard and a fuselage that has a large forward lifting wing and a small aft stabilizing wing and is able to lift a 250 lb man and surfboard approximately two feet above the water surface at slow paddling speeds riding a wave from underneath the water surface wherein said new art enables said hydrofoil surfboard to motor along on flat water at high speeds cruising or fielding for waves then said new art can retract a motorized structure completely out of the water while in motion to allow a surfer to catch then foil ride a wave or an ocean swell without power by means of two types of retractable motorized apparatus wherein the first type has a vertical strut that holds a propeller and cort nozzle in a down position motoring forward wherein said strut can retract horizontally up and out from the water surface wherein this retractable strut type can embody three similar versions. Also the second type has a torpedo shaped fuselage that contains a motor, a propeller and cort nozzle also embodying three similar versions that can travel up the foil mast stopping at said surfboard's bottom surface with the power shut off allowing the remaining under water foil apparatus to glide and free ride a wave or swell as it was designed to.