JP3698294B2 - Water jet propulsion system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a water jet propulsion device for a boat, and more particularly to a propulsion device that improves suction performance and propulsion force by using an impeller disposed in a pump casing as a spiral screw blade.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, an apparatus for providing a single impeller to a water jet propulsion device and running a ship is well known. A device for preventing cavitation and increasing the propulsive force by providing two impellers for the propulsion device is also known as disclosed in, for example, Japanese Patent Laid-Open No. 5-105190.
[0003]
[Problems to be solved by the invention]
In the water jet propulsion device provided with two conventional impellers, compared with the propulsion device provided with one impeller, the fluid pressure is increased to the extent that cavitation does not occur in the preceding impeller, The rear impeller can further increase the fluid pressure to enable high-speed propulsion, but the difference in the shape of the front and rear impellers and the turbulence of the water flow between them cause resistance to the fluid pressure. There was a fear. It is an object of the present invention to provide a propulsion device having an inducer function with improved suction performance.
[0004]
[Means for Solving the Problems]
The structure of this invention is the propulsion device that pressurizes the water sucked from the suction port of the suction casing at the bottom of the ship with the impeller of the pump casing and injects the pressurized water from the discharge casing to the stern rearward to propel the boat. The casing is formed in a cone shape, and a substantially conical hub is fixed to the tip of the drive shaft extending to the pump casing, and a spiral shape is formed on the periphery of the hub from the start end portion of the pump casing to the middle step portion. Along with screw blades, a plurality of guide blades are connected to the inner peripheral surface of the rear stage of the pump casing, and water flowing into the pump casing is continuously pressurized by a series of blade surfaces of the screw blades. Thus, the suction performance is enhanced by the propulsive force of the blade surface following the series, and the pressure is increased by centrifugal force. Further, the entire length of the hub around which the blades are wound is made longer than the diameter of the suction port of the pump casing, and the suction performance at the suction port is improved. 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 close to the inner peripheral surface of the pump casing, and the outer peripheral tip portion is the end portion of the suction casing. In order to improve the suction performance, the suspended matter is prevented from clogging the suction portion of the screw blade.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
The present invention is configured as described above. When the spiral screw blade is rotated, the water sucked from the suction port of the suction casing flows into the pump casing, flows into the start end of the screw blade, and the screw blade. As it is transferred to the subsequent stage, a series of blade surfaces of the screw blades exert 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 a thrust, so that water is inevitably guided and exhibits high suction performance. Next, the spiral pressurized water is converted into a linear flow by the guide vanes, and the pressurized water is injected from the discharge casing to the stern rear to propel the boat.
[0006]
【Example】
An embodiment of the present invention will be described in detail with reference to the drawings. First, in FIG. 1, reference numeral 1 denotes a jet propulsion device disposed at the stern of a boat 2. Disposed at the bottom of the ship, the water sucked from the suction casing 3 is transferred to the pump casing 4, pressurized by the impeller 5 disposed on the pump casing 4, and pressurized water is ejected from the deflector 7 behind the discharge casing 6. Then, the boat 2 is propelled by the reaction force. The jet propulsion apparatus 1 will be described in detail with reference to FIG. 2. A suction port 8 of the suction casing 3 is opened below the water surface, and a pump casing 4 disposed horizontally is connected to the rear portion of the suction casing 3. The cone shape is seen from the side. A drive shaft 11 connected to the output shaft 10 of the engine drive unit 9 extends inside the pump casing 4, and is fixed to the bearing case 12 and the drive shaft 11 that support the rear end of the drive shaft 11. A cone-shaped flow path is formed with the conical hub 13.
[0007]
A spiral screw blade 14 is wound around the peripheral portion of the hub 13 from the inlet diameter D1 of the starting end of the pump casing 4 to the maximum diameter part D2 of the middle stage, and is continuously twisted as shown in FIG. The water flow is pressurized and accelerated in the spiral centrifugal direction on the 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 amount of water sucked in the jet propulsion device 1. By providing a plurality of screw blades 14, volume efficiency and balance efficiency are improved. Further, if the length (L) of the hub around which the blade is wound and the diameter (D1) of the suction port of the pump casing 4 are set to L / D1 ≧ 1, the blade surface 14a of the screw blade 14 becomes longer. The centrifugal force and the pressure are increased toward the subsequent stage, thrust is generated by the injection speed of the pressurized water, and the suction performance can be enhanced by the inducer action of the suction port 8 of the pump casing 4.
[0008]
And the outer peripheral part 14b of the screw blade 14 is made to approach the inner peripheral surface of the pump casing 4, the outer peripheral tip part 14c is extended to the terminal part of the suction casing 3, and the suction port of the screw blade 14 is widened. The suction performance is improved, 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. A plurality of long twisted guide vanes 15 connected at both ends by the pump casing 4 and the bearing case 12 are provided in the flow path behind the screw vanes 14, and the spiral is pressurized and accelerated by the screw vanes 14. A flow path for converting the swirling flow into a linear flow is formed. Reference numeral 16 denotes an operating rod for switching the propulsion direction of the deflector 7, and reference numeral 17 denotes a reverse reverser.
[0009]
【The invention's effect】
The present invention is configured as described above, and the water flowing into the suction casing can be continuously pressurized and accelerated by the screw effect of the spiral screw blade. That is, in a conventional device in which two impellers are provided on the drive shaft, the difference in the shape of the impellers provided at the front and rear, and the turbulence of the water flow between them, may cause fluid pressure resistance. However, in the present invention, a screw blade having a continuous twisted blade surface is wound around a hub whose length is longer than the diameter of the suction port of the pump casing in a flow path formed in a cone shape. Having the set Te, water spirally in the centrifugal direction is pressurized-pressure speed, and thrust high in the flow path by injection speed, inducer action at the suction portion of the screw blade is generated, increased suction performance, Cavitation does not occur. And since the outer peripheral edge part of the screw blade is brought close to the inner peripheral surface of the pump casing and the outer peripheral tip part is extended to the terminal part of the suction casing, the suction port is widened and the suction performance is enhanced at the same time. The floating matter that has flowed into the pipe does not clog 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 partially 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]
DESCRIPTION OF SYMBOLS 3 Suction casing 4 Pump casing 5 Impeller 6 Discharge casing 11 Drive shaft 13 Hub 14 Screw blade 14b Outer peripheral part 14c Outer peripheral front end 15 Guide vane D1 Suction port diameter L Total length of the hub

Claims (2)

In a propulsion device that pressurizes water sucked from a suction casing (3) at the bottom of a ship with an impeller (5) of a pump casing (4) and injects pressurized water from the discharge casing (6) to the stern rear to propel the ship. The pump casing (4) is formed in a cone shape, and the entire length is longer than the diameter (D1) of the suction port of the pump casing (4) at the tip of the drive shaft (11) extending to the pump casing (4). A substantially conical hub (13) is fastened, and a spiral screw blade (14) is wound around the periphery of the hub (13) from the start end portion to the middle step portion of the pump casing (4). (4) A water jet propulsion apparatus characterized in that a plurality of guide vanes (15) are connected to the inner peripheral surface of the rear stage. A plurality of screw blades (14) wound around the hub (13) are arranged, the outer peripheral portion (14b) of the screw blade (14) is brought close to the inner peripheral surface of the pump casing (4), and the outer peripheral tip portion thereof The water jet propulsion device according to claim 1, wherein (14c) is extended to an end portion of the suction casing (3).

Images