JPH05270486A - Water jet propeller - Google Patents

Abstract

PURPOSE:To provide a water jet propeller excellent in performance and no generating cavitation under extensive steering conditions in a high speed boat. CONSTITUTION:In a water jet propeller which sucks water from an intake opened to a boat's bottom, pressurizes this sucked water through a pump impeller 5, sprays water from a nozzle 7 and propels the hull forward, it is provided with an on-off means 8 opening or closing a passage on an intake downstream side wall surface in rocking with a shaft 11 installed in a suction port 3 of the intake as the center, a driving means 10 driving this on-off means 8, and a control means controlling an opening of the on-off means 8 on the basis of speed and rotational frequency of the pump impeller 5, respectively.

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 mainly used as a propulsion device for a high-speed ship.

[0002]

2. Description of the Related Art In a water jet propulsion machine, water sucked from a suction port 3 of an intake duct 2 of a ship bottom 1 is pressurized by a pump impeller 5 rotated by a drive shaft 4 as shown in FIG. After rectifying, stern nozzle 7
It is jetted as a jet stream from this to obtain the thrust of the hull.

In such a water jet propulsion machine, a part of the dynamic pressure of the water flow generated in accordance with the increase of the ship speed can be used as the effective suction height of the suction portion of the pump impeller 5, so that general propeller propulsion is performed. Compared to a boat equipped with a machine,
It has excellent cavitation resistance during high-speed navigation, and has little additional resistance because there are no protrusions on the bottom of the ship. Therefore, the water jet propulsion machine is particularly suitable as a propulsion machine for a high-speed dedicated ship.

By the way, in the above water jet propulsion machine, the dynamic pressure recovery efficiency of the ship speed in the intake portion and the additional resistance have a great influence on the propulsion efficiency and the required power. A shape is used.

The characteristics of the intake flow will be described based on the operating conditions of the ship. If the ship speed is Vs and the flow velocity at the intake outlet is Vi, then the ratio Vi / Vs is the intake outlet flow velocity ratio. If the design speed of the ship is Vs0, the flow velocity Vi0 at the intake outlet at the rated output of the water jet propulsion becomes a function of the design speed Vs0 and the design suction specific velocity S of the pump impeller 5, and the intake outlet flow velocity ratio Vi0 / V.
s0 is roughly as shown in FIG. That is, it can be seen that the intake outlet flow velocity ratio Vi0 / Vs0 at the design speed decreases as the design speed Vs0 increases.

In general, when the design speed of a water jet propulsion vessel is 30 knots or more and the design suction specific speed S of the pump impeller 5 is 1200 (rpm-m ³ / min-m) or less, the intake outlet The flow velocity ratio Vi0 / Vs0 is 0.3-
It will be about 0.5. Since the pump operating point of the water jet propulsion machine does not change much depending on the output and the ship speed, the intake outlet flow velocity ratio Vi / Vs is V at the time of acceleration from low speed force.
It becomes larger than i0 / Vs0. Further, in the case of the sudden acceleration operation at full power, the value of the intake outlet flow velocity ratio Vi / Vs becomes a large value almost in inverse proportion to the ratio between the design speed Vs0 and the ship speed Vs.

FIGS. 12 (A) and 12 (B) show V for a general intake with a constant flow velocity Vi at the intake outlet.
The flow of the intake part when i / Vs is about 1.0 and Vi / Vs is about 0.3 is schematically shown in FIG. (B) shows the flow at the design speed.

In the case of FIG. 12 (A), the water flowing along the ship bottom 1 at the flow velocity (ship speed) Vs is sucked into the intake duct 2 as it is. On the other hand, as shown in FIG. 12 (B), when the boat is accelerated and the intake outlet flow velocity ratio Vi / Vs becomes smaller, the water that has jumped into the intake inlet 3 at high speed is rapidly decelerated in the intake duct 2, Partial backflow occurs on the stern side of the intake (tongue of the intake), resulting in loss in the intake and increased additional resistance. Therefore, the intake shown in FIG. 12 is used for a water jet propulsion machine having a comparatively low speed force in which the intake outlet flow velocity ratio Vi / Vs does not become so small.

In FIG. 13 (A), the intake outlet flow velocity ratio Vi / Vs = 0.3 which is suitable for high-speed navigation with an opening area smaller than that of the intake inlet 3 of FIG.
Shows the flow of. In the intake shown in FIG. 13 (A), the average flow velocity of the intake port 3 becomes equal to the ship speed Vs, and all the water that has jumped into the intake flows downstream of the intake and is designed to be smoothly decelerated to the flow velocity Vi. There is.

However, in this intake, when a rapid acceleration operation is performed from a low speed, as shown by the flow of the intake outlet flow velocity ratio Vi / Vs = 1.0 in FIG. Then, it is accelerated to about 3 times the ship speed,
When the design speed is high and the static pressure is significantly reduced near the intake port 3 of the intake, cavitation may occur and choking may occur.

[0011]

By the way, a water jet which has a very large design output of 40 knots or more and has a large hump at a rapid acceleration or a low speed force or a high output operation at a low speed force is required. Propulsion machines are required to have good dynamic pressure recovery efficiency of intakes at design speed and low added resistance, and intakes that do not cause cavitation during high output operation at low speeds.

[0012] However, in the intake used in the conventional water jet propulsion machine, it is difficult to realize high performance in a wide operation range from low power output to high power operation and ultra-high speed navigation. there were.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a water jet propulsion machine having high performance and free from cavitation under a wide range of operating conditions of a high-speed ship. ..

[0014]

In order to solve the above-mentioned problems, a water jet propulsion device according to the present invention sucks water from an intake opening at the bottom of the ship, pressurizes the sucked water with a pump impeller, In a water jet propulsion machine for injecting water from a nozzle to propel a hull, an opening / closing means for swinging around a shaft provided at the intake port of the intake to open / close a flow path on a downstream side wall surface of the intake, and this opening / closing means The driving means for driving and the control means for controlling the opening degree of the opening / closing means based on the boat speed and the rotation speed of the pump impeller are provided.

Another water jet propulsion apparatus of the present invention sucks water from an intake opening at the bottom of the ship, pressurizes the sucked water with a pump impeller, and jets water from a nozzle to propel the hull. In a jet propulsion device, a movable member provided with a tip end portion of a tongue portion of the intake so as to be able to move forward and backward with respect to a suction port of the intake, drive means for moving the movable member, ship speed and rotation of the pump impeller. And a control means for controlling the advance / retreat position of the movable member based on the number.

[0016]

In the present invention having the above-mentioned structure, the intake opening / closing means is normally held in the intake flow direction so that a flow path is formed on the intake downstream side wall surface, while the boat speed is increased and the intake outlet flow velocity is increased. When the ratio reaches a predetermined value, it is controlled to close the flow path on the side wall surface on the downstream side of the intake. Here, the control means calculates the intake outlet flow velocity ratio from the input ship speed and the rotational speed of the pump impeller, and sends a control signal to the drive device that drives the opening / closing means according to the value of the intake outlet flow velocity ratio. Output.

Further, in another invention, the movable member is usually held so that the opening area of the intake port of the intake is maximized, while the intake port is increased when the ship speed increases and the intake outlet flow velocity ratio decreases. The opening area of is controlled so as to be narrow. Here, the control means calculates the intake outlet flow velocity ratio from the input ship speed and the rotational speed of the pump impeller, and outputs a control signal to the drive device that drives the movable member in accordance with the value of the intake outlet flow velocity ratio. To do.

[0018]

Embodiments of the present invention will be described below with reference to the drawings.

1 to 5 show a first embodiment of a water jet propulsion device according to the present invention, and the same or corresponding parts as those of the conventional structure will be described by using the same reference numerals as those in FIG.

As shown in FIG. 1, the water jet propulsion machine pressurizes water sucked from an intake port 3 of an intake duct 2 of a ship bottom 1 by a pump impeller 5 attached to a drive shaft 4 driven by an engine. , Diffuser 6
After being rectified by the guide vanes, the jets are jetted as a high-speed jet stream from the stern nozzle 7 to obtain thrust of the hull.

Further, the suction port 3 of the intake duct 2 is
A relatively large opening area is formed so as to adapt to a low speed, and a stem shaft 11 is provided in the suction port 3 so as to penetrate the side wall of the intake duct 2. This stem shaft 11
A wing-shaped guide blade 8 as an opening / closing means is attached to the, and an arm 9 is attached to an end of the stem shaft 11. A hydraulic cylinder 10 as a driving means is connected to the arm 9, and by driving the hydraulic cylinder 10, the driving force is transmitted to the arm 9 and the guide blade 8 is swung about the stem shaft 11. ..

Further, as shown in FIG. 2, each signal of the ship speed Vs, the rotation speed N of the pump impeller 5 and the pump shaft input is inputted to the arithmetic control unit 12 as a control means, and the arithmetic control unit 12 is operated by the hydraulic pressure. A predetermined control signal is output to the control device 13. The hydraulic control device 13 receives a control signal from the arithmetic and control unit 12 and outputs a signal to a hydraulic device 14 that drives and controls the hydraulic cylinder 10.

Therefore, the guide blade 8 swings around the stem shaft 11 provided at the suction port 3 to open and close the flow path on the side wall surface on the downstream side of the intake. The opening of the guide blade 8 depends on the ship speed Vs and the pump impeller. It is controlled by the arithmetic and control unit 12 based on the rotation speed N of 5.

Next, the operation of this embodiment will be described.

FIG. 4 shows the posture of the guide vanes 8 and the flow of the intake portion when the intake outlet flow velocity ratio Vi / Vs is about 1.0. The opening a'of the guide vane 8 at this time is set to the maximum opening a'max. The flow at this time is shown in Figure 1.
Similar to the flow shown in FIG. 2 (A), it becomes an ideal flow during high-power operation at low speed. Further, in FIG. 5, the intake outlet flow velocity ratio Vi / Vs when the opening a ′ of the guide vane 8 is 0 and the flow path between the intake downstream side wall surface and the guide vane 8 is closed.
Shows the flow in the intake part around 0.3. The flow at this time is similar to the flow shown in FIG. 13 (A), which is suitable for high speed navigation.

That is, the guide vanes 8 are normally held in the flow direction of the intake so that a flow path is formed on the side wall surface on the downstream side of the intake, the ship speed Vs increases, and the intake outlet flow velocity ratio Vi / Vs has a value of 0.3. It is controlled so that the flow path on the side wall surface on the downstream side of the intake is closed when it becomes about 0.5.

Further, the operation of the control system of this embodiment will be described.

Water jet propulsion pump impeller 5
Since the operating point of does not move significantly due to the ship speed Vs and the rotation speed N of the pump impeller 5, the rotation speed N of the pump impeller 5
Alternatively, the flow rate, that is, the flow velocity Vi at the intake outlet can be predicted with an accuracy of ± 5% to ± 10% by detecting the pump shaft input. In this way, when predicting the flow velocity Vi at the intake outlet with high accuracy, it can be calculated from the flow rate-lift characteristic of the pump by detecting the pump rotation speed N and the suction pressure of the pump impeller 5.

The ship speed Vs and the number of revolutions N of the pump impeller 5 are input to the arithmetic and control unit 12, and the preset N-
After calculating the flow velocity Vi at the intake outlet from the characteristic value of Vi, the intake outlet flow velocity ratio f = Vi / Vs is calculated, and the intake outlet flow velocity ratio f ₀ = Vi ₀ at the design ship speed and rated output.
/ Vs0 is compared. FIG. 3 shows an example of a control characteristic curve in which the horizontal axis is f / f ₀ and the vertical axis is the opening a ′ of the guide blade 8.
The arithmetic and control unit 12 guide vanes opening is the value of f / f ₀ of 2.0 or more in A'max, reduce the opening at f / f ₀ is 2.0 or less, f / f ₀ is 1. A control signal that causes the opening degree to be 0 around 0 to 1.2 is output to the hydraulic control device 13.

As described above, according to this embodiment, a high intake outlet flow velocity ratio Vi / Vs and a low intake outlet flow velocity ratio V are used.
Eliminating the disadvantages of intake suitable for each i / Vs,
It is possible to realize the optimum flow condition of the intake section in a wide operating range from a high intake outlet flow velocity ratio Vi / Vs to a low intake outlet flow velocity ratio Vi / Vs. As a result, it is possible to prevent the occurrence of cavitation in the intake portion during high-power operation of the water jet propulsion device at low speeds, and to significantly reduce the dynamic pressure recovery efficiency and prevent additional resistance during high speed navigation.

In particular, a large, ultra-high-speed surface-effect vessel (S) that has a high hump resistance and requires high-power operation at low ship speeds.
The effect is extremely large in the water jet propulsion machine mounted on the ES).

FIGS. 6 to 8 show a second embodiment of the water jet propulsion device according to the present invention, and the same members as those in the first embodiment will be described with the same reference numerals. In the present embodiment, the intake tongue portion 20 of the intake duct 2 is separated from the intake duct 2 so as to be suitable for high design speed, and the movable tongue portion 21 as a movable member having the same shape as the wetted portion of the intake tongue portion 20 is provided. The movable tongue portion 21 is swung about the support shaft 22 by being rotatably supported by the support shaft 22 and by driving a hydraulic servomotor 24 as a driving unit supported by the support portion 23.

Further, each signal of the ship speed Vs, the rotational speed N of the pump impeller 5 and the pump shaft input is inputted to the arithmetic control unit 25 as a control means, and the arithmetic control unit 25 is set to the hydraulic control unit 26 by a predetermined value. Output a control signal. The hydraulic control device 26 receives a control signal from the arithmetic and control unit 25 and outputs a signal to a hydraulic device 27 which drives and controls the hydraulic servomotor 24. Sealing members 28 and 29 are attached to the sliding surfaces of the movable tongue portion 21 with respect to the intake duct 2 and the ship bottom 1, respectively, on their cylindrical surfaces to make the sliding portions airtight.

Next, the operation of this embodiment will be described.

FIG. 7A shows the flow in the intake portion when the stroke of the hydraulic servomotor 24 is maximum and Vi / Vs is around 0.3. The flow at this time is similar to the flow shown in FIG. 13 (A), and is a flow suitable for high-speed navigation.

FIG. 7B shows the hydraulic servomotor 24.
Indicates that the movable tongue 21 has moved to a direction in which the area of the opening of the intake duct 2 is expanded and Vi / Vs is about 1.0. The flow of FIG. 7 (B) is similar to the flow shown in FIG. 12 (A), and is a reasonable flow even during high power operation of the water jet propulsion machine at low speed.

Pump impeller 5 of water jet propulsion machine
Since the operating point of does not move greatly due to the ship speed Vs and the rotation speed N of the pump impeller 5, the flow rate, that is, the intake outlet flow velocity Vi, is ± 5 ±± 5 by detecting the rotation speed N of the pump impeller 5 or the pump shaft input. It can be predicted with an accuracy of 10%. Further, by detecting the rotation speed N and the suction pressure of the pump impeller 5, it is possible to obtain the flow rate with high accuracy based on the flow rate-lift characteristic of the pump.

Further, the arithmetic and control unit 25 has a ship speed Vs
And the rotational speed N of the pump impeller 5 are input, and after calculating the intake outlet flow velocity Vi from the preset characteristic value of N-Vi, f = Vi / Vs is calculated, and the design ship speed and rated output are obtained. Is compared with f ₀ = Vi ₀ / Vs ₀ . In Fig. 8, the horizontal axis is f
/ F ₀ , an example of a control characteristic curve in which the vertical axis is the stroke of the hydraulic servomotor 24 is shown.
When the value of f ₀ is 2 or more, the stroke S of the hydraulic servomotor 24 is minimized (Smin), and when the value of f / f ₀ is 2 or less, the stroke S is increased, and when f / f ₀ is around 1.0 to 1.2. A control signal that maximizes the stroke S (Smax) is output to the hydraulic control device 26.

Therefore, in this embodiment, the movable tongue portion 21 is held so that the opening area of the intake port 3 of the normal intake is maximized, while the ship speed Vs is increased and the intake outlet flow velocity ratio Vi / Vs is decreased. In this case, the opening area of the suction port 3 is controlled to be narrow. Here, the arithmetic and control unit 2
5 calculates the intake outlet flow velocity ratio Vi / Vs from the input ship speed Vs and the rotational speed N of the pump impeller 5, and moves the movable tongue 2 according to the intake outlet flow velocity ratio Vi / Vs.
A control signal is output to the hydraulic servomotor 24 that drives the drive motor 1. The rest of the configuration and operation are the same as in the first embodiment, so description thereof will be omitted.

FIG. 9 shows a modification of the second embodiment of the water jet propulsion machine according to the present invention. The same or corresponding members as those in the second embodiment will be designated by the same reference numerals. In this modified example, the movable tongue 21 is rotatably supported at one end of the ship bottom 1 about the support shaft 22, and the movable tongue 21 swings about the support shaft 22 by driving the hydraulic servomotor 24. Be moved. Therefore, also in this modification, the same effect as the second embodiment can be obtained. The rest of the configuration and operation are the same as in the second embodiment, so a description thereof will be omitted.

[0041]

As described above, according to the water jet propulsion device of the present invention, the intake outlet flow velocity ratio is calculated from the input ship speed and the pump impeller rotation speed, and the intake outlet flow velocity ratio is calculated. Since the opening and closing means and the position of the movable member are controlled according to the value of, the performance is high under a wide range of operating conditions of high-speed vessels and cavitation does not occur, improving vessel acceleration performance. At the same time, it is possible to improve the propulsion efficiency during high speed navigation.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing a first embodiment of a water jet propulsion device according to the present invention.

FIG. 2 is a block diagram showing a control system of the water jet propulsion machine shown in FIG.

FIG. 3 is a graph showing the control characteristics of FIG.

FIG. 4 is an explanatory view showing the operation of the water jet propulsion machine of FIG. 1.

5 is an explanatory view showing the operation of the water jet propulsion machine of FIG. 1. FIG.

FIG. 6 is a longitudinal sectional view showing a second embodiment of the water jet propulsion device according to the present invention.

7 (A) and 7 (B) are explanatory views showing the operation of the water jet propulsion device of FIG. 6.

8 is a graph showing the control characteristics of FIG.

FIG. 9 is a vertical cross-sectional view showing a modified example of the water jet propulsion machine of the second embodiment.

FIG. 10 is a vertical cross-sectional view showing a conventional water jet propulsion machine.

FIG. 11 is a graph showing the relationship between ship speed and intake outlet flow velocity ratio.

12 (A) and 12 (B) are explanatory views showing the flow of the intake portion of the conventional water jet propulsion machine.

13 (A) and 13 (B) are explanatory views showing the flow of the intake portion of the conventional water jet propulsion machine.

[Explanation of symbols]

 1 Ship Bottom 2 Intake Duct 3 Suction Port 4 Drive Shaft 5 Pump Impeller 6 Diffuser 7 Nozzle 8 Guide Blade (Opening / Closing Means) 9 Arm 10 Hydraulic Cylinder (Drive Means) 11 Stem Shaft 12 Arithmetic Control Device (Control Means) 13 Hydraulic Control Device 14 Hydraulic Device 21 Movable Tongue (Movable Member) 22 Support Shaft 23 Support Part 24 Hydraulic Servo Motor (Drive Means) 25 Arithmetic Control Device (Control Means) 26 Hydraulic Control Device 27 Hydraulic Device

Claims (2)

[Claims] 1. A water jet propulsion machine for sucking water from an intake opening at the bottom of a ship, pressurizing the sucked water with a pump impeller, and injecting water from a nozzle to propel the hull, to a suction port of the intake. An opening / closing means for swinging around the provided shaft to open / close a flow path on the intake downstream side wall surface; and a driving means for driving the opening / closing means,
A water jet propulsion device, comprising: a control unit that controls the opening degree of the opening / closing unit based on a ship speed and the rotation speed of the pump impeller. 2. A water jet propulsion machine for sucking water from an intake opening at the bottom of the ship, pressurizing the sucked water with a pump impeller, and injecting the water from a nozzle to propel the hull of the intake, A movable member whose front end is provided so as to move forward and backward with respect to the intake port of the intake, drive means for moving the movable member, and a forward and backward position of the movable member based on the ship speed and the rotation speed of the pump impeller. A water jet propulsion machine comprising: a control means for controlling.