JP2000326895A - Water jet propulsion device - Google Patents

Abstract

(57) [Summary] (Modified) [Problem] To improve suction performance and propulsion. A helical screw blade (14) is wound around a conical hub (13) fixed to a drive shaft (11) extending from a cone-shaped pump casing (4) from the start end to the middle part of the pump casing (4). The guide blades 15 are connected to the latter stage of the pump casing, and the water flowing into the pump casing is continuously pressurized by a series of blade surfaces. The total length L of the hub around which the screw blades are wound is made longer than the diameter D1 of the suction port of the pump casing, and the water flow is pressurized and accelerated in the spiral centrifugal direction. Generates an inducer action in the suction section. Prevents cavitation. A plurality of screw blades wound around the hub are arranged, the outer periphery of the screw blade is made to approach the inner peripheral surface of the pump casing, and the outer peripheral end is extended to the suction casing, so that the floating material is supplied to the suction portion of the screw blade. It was not clogged.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water jet propulsion device for a watercraft, and more particularly to a propulsion device in which an impeller provided in a pump casing is a helical screw blade to improve suction performance and propulsion.

[0002]

2. Description of the Related Art Heretofore, a water jet propulsion apparatus provided with one impeller to make a boat run is well known. A device for preventing cavitation and increasing propulsion by providing two impellers of a propulsion device in parallel is also known, for example, as described in JP-A-5-105190.

[0003]

In a water jet propulsion device having two conventional impellers, cavitation is performed by a former impeller in comparison with a propulsion device having one impeller. Increase the fluid pressure to such an extent that
The latter impeller further increases the fluid pressure and enables high-speed propulsion.However, differences in the shape of the front and rear impellers and the turbulence of the water flow between them cause resistance to fluid pressure. There was fear. An object of the present invention is to provide a propulsion device having an inducer function with improved suction performance.

[0004]

According to the structure of the present invention, the water sucked from the suction port of the suction casing at the bottom of the ship is pressurized by the impeller of the pump casing, and the pressurized water is jetted rearward from the discharge casing to the stern. In the propulsion device, the pump casing is formed in a cone shape, a substantially conical hub is fastened to the tip of a drive shaft extending from the pump casing, and the pump casing is provided around the hub. Along with winding a spiral screw blade from the starting end to the middle stage, a plurality of guide blades are connected to the inner peripheral surface of the latter stage of the pump casing, and water flowing into the pump casing is passed through a series of blade surfaces of the screw blade. Continuously pressurized, the suction performance is enhanced by the propulsive force of the blade surface that continues in series, and the pressure is increased by centrifugal force. Further, the entire length of the hub around which the blade is wound is made longer than the diameter of the suction port of the pump casing, so that the suction performance at the suction inlet portion is enhanced. Then, a plurality of blades wound around the hub are arranged to improve the balance performance, the outer peripheral portion of the screw blade is brought closer to the inner peripheral surface of the pump casing, and the outer peripheral end portion is set to the outer peripheral end of the suction casing. The portion extends to the end of the suction casing to enhance suction performance and prevent suspended matter from clogging the suction portion of the screw blade.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is configured as described above. When a spiral screw blade is rotated, water sucked from a suction port of a suction casing flows into a pump casing, and a starting end of the screw blade is formed. As it flows into the section and is transferred to the subsequent stage of the screw blade, a series of blade surfaces of the screw blade exerts a screw effect. Then, the water guided to the series of blade surfaces generates a centrifugal force to increase the pressure, and is accelerated to generate thrust, inevitably leading to water, and exhibiting high suction performance. Next, the spiral pressurized water is converted into a linear flow by the guide blades, and the pressurized water is jetted rearward from the discharge casing to propel the boat.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail with reference to the accompanying drawings. First, in FIG. 1, reference numeral 1 denotes a jet propulsion device disposed at the stern of a boat 2;
Is disposed at the bottom of the stern of the hull 2 and transfers water sucked from the suction casing 3 to the pump casing 4.
Pressure is applied by an impeller 5 disposed in the pump casing 4, and pressurized water is ejected from a deflector 7 behind the discharge casing 6 to propel the boat 2 by the reaction force. The jet propulsion device 1 will be described in detail with reference to FIG. 2. The suction port 8 of the suction casing 3 is opened below the water surface, and a horizontally arranged pump casing 4 is connected to the rear of the suction casing 3. It has a cone shape when viewed from the side. A drive shaft 11 connected to an output shaft 10 of the engine drive 9 extends inside the pump casing 4, and is fixed to the drive shaft 11 and a bearing case 12 that supports the rear end of the drive shaft 11. A conical flow path is formed with the conical hub 13 thus formed.

[0007] A helical screw blade 14 is wound around the periphery of the hub 13 from the diameter D1 of the suction port at the start end of the pump casing 4 to the maximum diameter part D2 at the middle stage, and as shown in FIG. The pressure of the water flow is increased in the spiral centrifugal direction by the twisted blade surface 14a.
In the embodiment of FIG. 3, two screw blades 14 are provided, but a plurality of screw blades 14 may be provided depending on the suction water amount of the jet propulsion device 1. By providing a plurality of screw blades 14, volume efficiency and balance efficiency are improved. Further, the total length (L) of the hub around which the blade is wound and the diameter (D of the suction port of the pump casing 4)
If the size of 1) is L / D1 ≧ 1, the blade surface 14a of the screw blade 14 becomes longer, the centrifugal force and the pressure are increased toward the later stage, and thrust is generated by the injection speed of the pressurized water, and the pump casing The suction performance can be enhanced by the inducer function of the suction port 8 of the suction nozzle 4.

The outer peripheral portion 14 of the screw blade 14
b is made to approach the inner peripheral surface of the pump casing 4, and the outer peripheral tip 14 c is extended to the terminal end of the suction casing 3,
The suction port of the screw blade 14 is widened to improve the suction performance, and at the same time, the suspended matter flowing into the suction casing 3 is prevented from clogging the suction portion of the screw blade 14. In the flow path behind the screw blade 14, a plurality of long twisted guide blades 15 having both ends connected by the pump casing 4 and the bearing case 12 are provided. A flow path for converting the swirling flow into a linear flow is formed. Reference numeral 16 denotes an operating rod for switching the direction of propulsion of the deflector 7, and reference numeral 17 denotes a reverser for reverse movement.

[0009]

The present invention is configured as described above,
Due to the screw effect of the helical screw blade, the pressure of the water flowing into the suction casing can be continuously increased. In other words, in the conventional device in which two impellers are provided on the drive shaft, the shape of the front and rear impellers is different, and there is a possibility that the flow of water between the impellers may be disturbed, resulting in resistance to fluid pressure. According to the present invention, however, since a screw blade having a series of twisted blade surfaces is provided in the flow path formed in a cone shape, the water flow is increased in pressure in the spiral centrifugal direction. The thrust is increased, the thrust is increased in the flow path due to the injection speed, and an inducer action occurs at the suction portion of the screw blade, so that the suction performance is improved and cavitation does not occur. The outer peripheral edge of the screw blade is made closer to the inner peripheral surface of the pump casing, and the outer peripheral tip is extended to the terminal end of the suction casing. Is not clogged in the suction part of the screw blade. If a plurality of screw blades are provided, volume efficiency and balance efficiency are improved.

[Brief description of the drawings]

FIG. 1 is a schematic side view of a boat provided with a jet propulsion device according to the present invention.

FIG. 2 is a partial longitudinal side view of the jet propulsion device according to the present invention.

FIG. 3 is a perspective view of a screw blade according to the present invention.

[Explanation of symbols]

 Reference Signs List 3 suction casing 4 pump casing 5 impeller 6 discharge casing 11 drive shaft 13 hub 14 screw blade 14b outer peripheral portion 14c outer peripheral tip portion 15 guide blade D1 diameter of suction port L total length of hub

Claims (3)

[Claims] 1. A water suctioned from a suction casing (3) at the bottom of a ship is pressurized by an impeller (5) of a pump casing (4), and pressurized water is jetted rearward from a discharge casing (6) to stern the boat. In the propulsion device to be propelled, the pump casing (4) is formed in a cone shape, and a substantially conical hub (13) is fastened to a distal end of a drive shaft (11) extending to the pump casing (4). A spiral screw blade (14) is wound around the periphery of the hub (13) from the start end of the pump casing (4) to the middle stage, and a plurality of sheets are wound around the inner peripheral surface of the rear stage of the pump casing (4). A water jet propulsion device comprising guide vanes (15) connected thereto. 2. The water jet propulsion according to claim 1, wherein the total length (L) of the hub around which the screw blade (14) is wound is longer than the diameter (D1) of the suction port of the pump casing. apparatus. 3. A plurality of screw blades (14) wound around the hub (13) are provided, and the screw blades (1) are provided.
The outer peripheral portion (14b) of (4) is brought closer to the inner peripheral surface of the pump casing (4), and the outer peripheral tip portion (14c) is extended to the terminal end of the suction casing (3). Or the water jet propulsion device according to 2.