JPH02128993A - Water jet propulsive device - Google Patents

Abstract

PURPOSE:To enhance the propulsive efficiency by allowing an inner and an outer nozzle to make relative rotation at the time of high speed cruising, providing the nozzles each with a plurality of holes which are not identical to each other, and making the flow path section area of a jetting water stream only the bore of the inner nozzle. CONSTITUTION:In a water jet propulsive device to be equipped on a high speed vessel, the water stream led in from an water intake at the vessel bottom is guided to a pump casing 3 and pressurized by a pump impeller 5 rotated by a drive shaft 10, and upon baffling with a diffuser 6, it jets out of a jet nozzle 7. This jet nozzle 7 is composed of an inner nozzle 14 and an outer nozzle 17, which is rotated by a drive device 18. A plurality of jet holes 16 provided in the outer nozzle 17 shall be out of alignment from holes 15 in the same number provided in the inner nozzle 14, and the water flow path 22 of the outer nozzle 17 is blocked by choking these holes 15. Thereby the jetting speed of water stream is increased to lead to enhancement of the propulsive efficiency during high speed cruising.

Description

Detailed Description of the Invention (Objective of the Invention) (Industrial Field of Application) The present invention relates to a water jet propulsion device used as a propulsion device for high-speed boats, which has excellent thrust characteristics especially during low-speed navigation. The present invention also relates to a water jet propulsion device with high durability and nozzle efficiency of the injection nozzle part.

(Prior Art) Generally, as shown in FIG. 6, a water jet water pump includes a water guide duct 4 that guides water taken from a water intake 2 provided at the bottom of a watercraft 1 into a pump casing 3, and a water guide duct 4 that guides water into a pump casing 3, as shown in FIG. Pump impeller 5 arranged inside the casing 3
and a differential user 6 connected to the secondary side of the pump casing 3. A guide vane 8 and a needle 9 are provided in the diffuser 6 to straighten the pressurized water flow and guide it to the nozzle opening of the injection nozzle 7. In addition, the pump impeller 5
A drive shaft 10 that rotates at high speed is operated by a device 1ia.

A water flow 11 introduced from the water intake 2 passes through a water guide duct 4 and is guided to the pump casing 3. Guided water flow 11
is pressurized by a pump impeller 5 rotated by a drive shaft 10, and after being rectified by guide vanes 8 of a diffuser 6, the pressurized water is injected at high speed from an injection nozzle 7 provided at the stern.

The watercraft 1 gains thrust from the reaction of this water jet.

In this water jet propulsion device, efficiency is improved because the pressure of the water flow introduced into the water intake 2 increases as the ship speed increases. In other words, a boat equipped with a water jet propulsion device uses a part of the dynamic pressure of the water flow generated as the ship speed increases as the right-hand effect suction height (NFSH) of the suction part of the pump impeller 5. Compared to ships equipped with general propeller propulsion devices, it is possible to
It has high propulsion efficiency during high-speed navigation and excellent cavitation resistance. Therefore, the water jet 11 is especially suitable as a propulsion device for high-speed charter boats.

However, the injection holes of conventional water jet propulsors for high-speed boats often have a fixed nozzle diameter, and the injection speed of the water jet is designed to achieve the highest propulsion efficiency during high-speed navigation. It had been. Therefore, when cruising at low speed, the rate of movement of the engine 11 decreases significantly, and there is a drawback that the acceleration performance is particularly poor when starting from a stopped state or when switching from low speed operation to high output operation.

In order to solve these problems, by changing the flow passage cross-sectional area of the injection hole according to the ship speed and changing the jet flow velocity of the water stream, it is possible to improve the It efficiency in the entire range from low speed to high speed. A variable nozzle capable of this is disclosed, for example, in Japanese Patent Publication No. 55-276.

As shown in FIG. 7, this variable nozzle has an elastic ring 12 attached to the inner peripheral surface of the nozzle opening of the injection nozzle 7.
A working fluid is introduced into an expansion chamber 13 formed between the elastic ring 2 and the inner circumferential surface, and the inner surface shape of the elastic ring 12 is changed by increasing or decreasing the pressure, thereby changing the cross-sectional area of the water flow path. That is, during low-speed navigation, the pressure inside the expansion chamber 13 is increased to adjust the flow passage cross-sectional area to be as wide as Ajl,
Acceleration performance is improved by reducing the jet flow velocity of the water beam 11.

On the other hand, during high-speed cruising, the working fluid in the expansion chamber 13 is reduced in pressure and narrowed so that the cross-sectional area of the flow path is narrowed to Aj2, increasing the jet velocity of the water jet jetted from the jet nozzle 7 and improving propulsion efficiency. I'm letting you do it.

(Problems to be Solved by the Invention) In the variable nozzle of the conventional water jet propulsion device, as shown in FIG. 7, during low-speed navigation, the elastic ring 12 forms a nozzle body with a smooth inner surface shape, The cross-sectional area Aj1 of the water flow jetted from the jet nozzle 7 is approximately equal to the cross-sectional area A of the jet nozzle 7. on the other hand,
At high speed, the elastic ring 12 has a shape that is in close contact with the inner peripheral surface of the injection nozzle 7, and the water flow forms a contraction flow along the inner peripheral surface of the contracted elastic ring 12. Therefore, the flow path cross-sectional area of the jetted water stream is reduced to Aj2. However, in the injection nozzle 7 where the water flow further contracts after being discharged from the injection nozzle 7, the nozzle efficiency is 6 to 10.
%, there is a problem that thrust efficiency decreases, especially during high-speed cruising.

Furthermore, although the pressure distribution within the expansion chamber 13 is uniform, a large pressure distribution is formed on the inner surface of the elastic ring 12 in the direction of the water jet, and a large pressurizing force is constantly exerted on the inner surface of the elastic ring 12. Therefore, the elastic ring 12 is subject to severe wear and tear, resulting in decreased durability and reliability, which poses difficulties in maintenance management.

The present invention has been made with the aim of solving the above-mentioned problems, and it is possible to improve the L force efficiency and increase the durability and nozzle efficiency of the injection nozzle portion during low-speed navigation of ships. The purpose is to provide 31 water jet thrusters that can be used.

(Structure of the Invention) (Means for Solving the Problems) The present invention provides thrust by pressurizing water flow from a water intake provided at the bottom of the ship using a pump impeller and injecting it from an injection nozzle provided at the stern of the ship. In the water jet propulsion device, the injection nozzle includes an inner nozzle having a plurality of holes around a main nozzle opening whose diameter is reduced in the injection direction of the water flow, and an inner nozzle arranged outside the inner nozzle. an outer nozzle having injection holes that can be selectively aligned with the holes of the outer nozzle, the inner and outer nozzles are rotated relative to each other by a driving means to adjust the water flow injected from the plurality of injection holes of the outer nozzle; The present invention is characterized in that the cross-sectional area of the water stream jetted from the jet nozzle can be changed.

(Function) Since the present invention is configured as described above, when the watercraft is traveling at high speed, the inner nozzle and the outer nozzle are rotated relative to each other by the driving means so that the plurality of injection holes of the outer nozzle and the inner nozzle are connected to each other. The plurality of holes of the inner nozzle are opened by making the radial positions of the plurality of holes not coincident with each other. As a result, the flow path cross-sectional area of the water stream to be injected is only the opening diameter of the inner nozzle, which is the frontage cross-sectional area of the smallest injection nozzle. Therefore, the ejection speed of the water stream from the injection nozzle increases, and the propulsion efficiency increases.

On the other hand, when a watercraft starts or sails at low speed, the inner nozzle and the outer nozzle are rotated relative to each other by the driving means until the plurality of holes in the inner nozzle and the plurality of injection holes in the outer nozzle are aligned with each other. The flow path cross-sectional area of the water flow is the largest opening cross-sectional area that is the sum of the opening diameter of the inner nozzle and the plurality of injection apertures of the outer nozzles. Therefore, the average speed of jetting from the jetting nozzles including the inner nozzle decreases,
Propulsion efficiency in low speed range is improved.

(Embodiments) Hereinafter, illustrated embodiments of the present invention will be described in detail. 1 and 2 show an embodiment of the water jet propulsion device according to the present invention, with FIG. 1 showing the water jet propulsion device during low-speed navigation, and FIG. 2 showing the water-jet propulsion device during high-speed navigation. In FIGS. 1 and 2, the same members as those of the conventional example shown in FIG.

I will explain.

The water jet propulsion device according to this embodiment guides a water flow introduced from a water intake provided at the bottom of a watercraft to a pump casing 3, and the guided water flow is applied by a pump impeller 5 rotated by a drive shaft 10. After being rectified by the guide vanes 8 of the diff user 6, this pressurized water stream is injected at high speed from the injection nozzle 7 provided at the stern, and thrust is obtained by the water injection θ reaction. Further, in the diff user 6, a needle 9 is provided together with a guide vane 8 to rectify the pressurized water flow and guide it to the injection hole 7.

The injection nozzle 7 provided at the stern is composed of an inner nozzle 14 and an outer nozzle 17, and the inner nozzle 14 has a main nozzle opening 14a whose diameter is gradually reduced in the injection direction of the water flow, and a main nozzle in the middle of the flow path. A plurality of (four in this embodiment) approximately elliptical or elongated holes (sub-nozzle holes) 15 are bored around the mouth portion 14a. Further, an outer nozzle 17 is disposed outside the inner nozzle 14 and is concentric with the inner nozzle 14 and is freely rotatable. An elliptical or elongated injection hole 16 is provided.

The outer nozzle 17 is provided with a drive device 1ff18 as a drive means such as a servo motor or a step motor that rotates the outer nozzle 17 and adjusts the water flow ejected from the injection hole 16, and this drive device i! ! By operating 18, the opening cross-sectional area of the water jet 16 from the injection nozzle 7 can be changed.

An outer nozzle 17 having a plurality of injection holes 16 is rotatably attached to the outer circumferential side of the inner nozzle 14 via a bearing 19, and a drive device 18 for applying rotational force to the outer nozzle 17 is connected to the differential user 6. It is attached to the outer circumference of the Furthermore, the four holes 15 formed in the inner nozzle 14 and the upstream side of the four injection holes 16 of the outer nozzle 17 have the same opening diameter. When rotated, the inner nozzle 14
Hole 15 of I! A sealing member 20 for sealing is provided. The drive device 18 is connected to the control device 21, and this! The 11111 device 21 is connected to a ship speed detector 25 for detecting ship speed.

Also, a driving device! ! 18 causes the outer nozzle 17 to rotate radially through an angle of 45 degrees in the forward or reverse direction.

Next, the operation of this embodiment having the above configuration will be explained.

When starting a boat or navigating at low speed, please refer to Figure 1 (
As shown in A) and (B), a drive signal for rotating the outer nozzle 17 is sent from the control device M21 to the drive device 18, and when the drive device 18 rotates the outer nozzle 17 by, for example, 45 degrees, the flow of the inner nozzle 14 is increased. It stops at a position where the upstream side of the injection hole 16 of the outer nozzle 17 coincides with the four holes 15 bored in the middle of the road. As a result, the flow channel 2 passes through the hole 15 of the inner nozzle 14 and reaches the injection hole 16 of the outer nozzle 17.
2 is formed, and the opening diameter of the inner nozzle 14 and the outer nozzle 1
Jet water FltJ that combines four injection diameters of 7.
21. J22 is injected. This jet water flow J,
The overall cross-sectional area of the flow path of J becomes the maximum, so the average jetting speed ■j2 of the jet water "21.J22" becomes lower, improving the propulsion efficiency during low-speed navigation.

Next, when the boat is accelerated and the boat speed detector 25 detects that the boat speed has increased sufficiently, the drive device 18 is activated through the control device ff21 as shown in FIGS. 2(A) and (B). Then, the outer nozzle 17 is rotated by 45rI in the opposite direction to the above, and the positions of the upstream side of the injection hole 16 of the outer nozzle 17 and the hole 15 of the inner nozzle 14 are made to be mismatched, and the sealing member 20 is installed between them. Hole 1 of inner nozzle 14
5 (1) to block the flow channel 22 of the outer nozzle 17. As a result, the ejected jet water flow J
The cross-sectional area of the flow path is only the opening diameter dj1 of the inner nozzle 14, and therefore the average jetting speed of the jet water flow J1 is
j1 increases, and the propulsion efficiency during high-speed cruising is kept high.

Furthermore, the operation of the water jet propeller of this embodiment that performs the above operations will be explained based on FIGS. 3 to 5.

In general, as shown in Fig. 3, the water diene installed on a high-speed boat is the propulsion efficiency η of the propulsion device, & (1) below.
The jet velocity ratio is varied by the spear as shown in the equation.

Jet i speed ratio Hull speed■.

Normally, this jet flow velocity ratio is 1.5 to 1:81! i!
It is known that the propulsion efficiency ηj is highest at a value of .

In conventional high-speed boats, the nozzle opening diameter of the injection hole is set based on the maximum propulsion efficiency point at R high speed, or is set slightly larger than the maximum propulsion efficiency point from the perspective of reducing the weight and size of the propulsion unit. It is set to be.

Therefore, as shown in FIG. 3, when the watercraft is traveling at low speed, the jet flow speed ratio increases, and the propulsion efficiency ηj decreases.

Here, the pump operating point of the water jet propeller is determined by the flow path resistance corresponding to the flow path cross-sectional area in the injection nozzle, as shown in FIG.

That is, during high-speed sailing when the diene (water flow J1) is ejected only from the inner nozzle 14 having a small opening diameter dj1 as shown in FIG. Intersection a with the curve (Q-8 curve)
is the operating point.

On the other hand, during low-speed navigation, a water stream is ejected from the 010 section of the inner nozzle 14 and the outer nozzle 17 having a plurality of injection holes 16, and the flow passage resistance S decreases because the flow passage cross-sectional area increases. Therefore, the operating point moves to the intersection of the Q-1-1 curve and the flow path resistance curve B. At this time, the pump flow rate Q increases, but the pump total head 1'' decreases, so the jet water flow J2
1. The ejection velocity vj2 of J22 decreases, and the propulsion efficiency ηj increases.

FIG. 5 shows a thrust characteristic curve Tj1 when a water stream is injected only from the inner nozzle 14 having a small-diameter frontage dj1, and the outer nozzle 1 having the inner nozzle 14 and a plurality of injection holes 16.
Thrust force characteristic curve T when water flow is jetted from both sides of 7
This is a graph showing the relationship between j2 and ship speed ■. Further, the OR curve shows the relationship between the ship speed V and the ship resistance R. The difference between the Jli force values Tj1 and Tj2 and the hull resistance R at a certain ship speed indicates the acceleration margin at that ship speed.

When only the inner nozzle 14 having the small-diameter opening dj1 is used, the thrust force T during starting and low-speed cruising is small, and there is little acceleration margin. In particular, the wave-making resistance is large until the ship reaches a speed at which the influence of the viscous force of water is reduced, and the acceleration margin shown on the humb resistance line showing the change in the wave-making resistance 1f1 becomes very small.

On the other hand, when the outer nozzle 17 having a plurality of injection holes 16 is used simultaneously with the inner nozzle 14, the thrust force T becomes large during starting and low-speed cruising, and sufficient acceleration margin is ensured. However, during high-speed navigation, there will be a lack of thrust, and the maximum speed reached will be smaller than when using the small-diameter inner nozzle 14.

Therefore, the thrust characteristic curve Tj1 and the thrust characteristic curve Tj2
By switching the outer nozzle 17 using the jet water jet 18 as a boundary at the ship speed Vsc corresponding to the intersection with It becomes possible to secure sufficient thrust T during navigation.

As described above, according to this embodiment, since the nozzle to be rotated is the outer nozzle 17, the drive device fi18 can be easily attached and maintenance can also be facilitated.

Note that the present invention is not limited to the above-mentioned embodiments, and various modifications are possible. For example, the number of holes 15 of the inner nozzle 14 and the number of injection holes 16 of the outer nozzle 17 are set to be the same, but are they different? The number may be 12, or the number may be a plurality other than four as in the above embodiment. Further, in the above embodiment, the outer nozzle 17 is rotated by the drive VtV1118, but the outer nozzle 17 may be fixed and the inner nozzle 14 is rotated.In short, the inner nozzle 14 and the outer nozzle 1
7 should be relatively rotated.

〔Effect of the invention〕

As mentioned above, water jet II i according to the present invention
According to the IU device, when a boat is sailing at high speed, the plurality of injection holes in the outer nozzle are rotated by the driving means, and the flow path cross-sectional area of the injected water flow is the opening cross-section of the inner nozzle with the smallest diameter of 1 m. It becomes the area. Therefore, the ejection speed of the water stream from the injection nozzle increases, and the propulsion efficiency increases.

On the other hand, when a boat starts or sails at low speed, the inner nozzle and outer nozzle are rotated relative to each other, and the positions of the inner nozzle hole and the outer nozzle injection hole are aligned, so that the cross-sectional area of the water flow can be adjusted. is the largest opening cross-sectional area. Therefore, the average jet speed of the water flow from the jet nozzle is reduced, and the propulsion efficiency in the low speed region is improved.

In other words, the cross-sectional area of the injection nozzle can be changed according to the ship's speed, and the water jet speed can be set, so propulsion efficiency can be maintained at a high level over a wide range of operating ranges from launch port 1 to high-speed sailing. can do. In particular, the propulsion efficiency in the low-speed operating range can be significantly improved compared to the conventional example.

Furthermore, unlike the conventional case in which the variable nozzle is made of an elastic material such as an elastic ring, according to the present invention, the variable nozzle is made of a rigid member, and has a smooth shape that does not form contractures. Because of this structure, the nozzle efficiency is high and the injection nozzle has high rigidity against the pressure applied by the water flow, making it possible to significantly improve the operating efficiency, durability, and reliability of the propulsion unit. , maintenance management can also be simplified.

Figures 1 (A>, (B)) show an embodiment of the water jet propulsion device according to the present invention, and Figures (A) and (B) show the state during low speed operation. is a view of the injection nozzle in the Ah direction in Fig. 1 (Δ), Fig. 2 (A) and (
B) also shows the state during high-speed operation, the same figure (A) is a cross-sectional view, the same figure (B) is an 8-direction arrow view of the injection nozzle in FIG. Figure 4 is a graph that explains the pump operating point, Figure 5 is a graph that shows the relationship between lit force and hull resistance with respect to ship speed, and Figure 6 is a graph that shows the relationship between the ratio and m forward rate. A sectional view showing the structure of a conventional water jet propeller; the seventh factor is a sectional view showing the structure of a conventional variable nozzle.

DESCRIPTION OF SYMBOLS 1... Boat, 2... Water intake, 3... Pump casing, 5... Pump impeller, 7... Injection nozzle, 8
... Guide vane, 14... Inner nozzle, 15... Hole, 16... Injection hole, 17... Outer nozzle, 18...
・Drive equipment (drive means), 2o...Seal member, 21
...Control device 22.22...Flow channel.

[Brief explanation of drawings]

Sidet, 'L Llr Go K (5R-/) 'Ij'! all l
// )Koimine 11J VS Figure 5 Figure 5

Claims (1)

[Claims] In a water jet propulsion device that obtains thrust by pressurizing a water flow introduced from a water intake provided at the bottom of the ship using a pump impeller and injecting it from an injection nozzle provided at the stern, the injection nozzle has a diameter that decreases in the direction in which the water flow is ejected. An inner nozzle having a plurality of holes formed around the main nozzle opening, and an outer nozzle having injection holes arranged outside the inner nozzle that can selectively match the holes of the inner nozzle. , the inner side
Water jet propulsion characterized in that the outer nozzle is relatively rotated by a driving means to adjust the water flow ejected from the plurality of injection holes of the outer nozzle, and the cross-sectional area of the water flow ejected from the injection nozzle can be freely changed. vessel.