JPH0520639Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a water jet propulsion device having a characteristic on the upstream side of the fairing part of the water intake part.

[Conventional technology]

Figures 3 to 5 show examples of conventional waterjet propellers. Figure 3 is a structural diagram of the conventional one, and Figures 4 and 5 show the front ceiling part (fairing part) of the water intake part. A schematic diagram for explaining cases in which the angle of inclination α formed with the bottom of the ship and the angle of flow of water to the water intake portion are equal and different are shown.

In the above figure, 1 is the impeller of the propeller, 2 is the guide vane, 3 is the nozzle, and 4 is the impeller 1 and the guide vane 2.
5 is a water intake section, 6 is a steering device, and 7 is a bottom of the ship.

The upper part of the water intake part 5 is connected to the casing 4, is provided toward the front bottom of the ship, and is open to the bottom 7 of the ship.

When the waterjet propulsion device begins to rotate, water flows in from the opening in the bottom 7, passes through the water intake part 5 and the casing 4, becomes a jet from the nozzle 3, and is ejected to generate thrust, causing the ship to move forward. The thrust at this time is T
=ρQ(Vj−Vs). (T is the thrust, Q is the flow rate of water, ρ is the mass per unit volume of water, Vj
is the jet flow velocity, and Vs is the ship speed. ) The inclination angle α between the front ceiling part (fairing part) of the water intake part 5 and the ship's bottom is such that the opening in the ship's bottom 7 is set so that the loss due to water flowing into the water intake part 5 is small at ship speeds that are normally used frequently. The velocity triangle is designed to be approximately equal to the inclination angle α of the water intake portion 5 (see FIG. 4).

In addition, in the velocity triangle, tanα≒Vi/Vs,
Vi=Q/A. (Note that Vi represents the flow rate of water flowing into the intake inlet, and A represents the area of the inlet of the water intake.) However, when the ship speed is slow, the speed triangle as shown in Figure 5 The inclination angle α between the front part of the section 5 and the bottom of the ship becomes a mismatch angle α', which increases the collision loss of the inflowing water to the water intake section 5, which not only increases the hull resistance but also reduces the efficiency of the propulsion device. descend.

[Problem that the invention attempts to solve]

In this way, in conventional waterjet propulsion devices with a fixed water intake shape, when the ship's speed is reduced, the velocity triangle at the entrance to the bottom of the ship is determined by the slope formed by the front part of the water intake and the bottom of the ship, as shown in Figure 5. This has the disadvantage that it does not match the angle α, increases the collision loss of water flowing into the inlet, and reduces the overall efficiency of the propulsion device.

The present invention aims to eliminate the above-mentioned drawbacks, and provides a water jet propulsion device that has an optimal water intake inlet shape depending on the speed of the ship by changing the angle of inclination of the front lower part of the water intake. With the goal.

[Means for solving problems]

For this reason, the water jet propulsion device of the present invention takes water from a water intake section provided at the bottom of the ship facing forward and downward, and uses an impeller provided in a casing connected to the upper part of the water intake section to In a water jet propulsion device that discharges water through a nozzle to the rear of a ship, a flexible elastic body is stretched at the front lower part of the water intake part, and the flexible elastic body is formed as part of a wall inside the ship in front of the water intake part. The present invention is characterized by comprising a pressurizing chamber, and a pressurizing/depressurizing means connected to the pressurizing chamber for expanding and contracting the flexible elastic body.

[Effect]

With the above configuration, it is possible to change the angle of inclination of the front lower part of the water intake, so it is possible to create the optimal shape of the water intake inlet depending on the speed of the ship.

〔Example〕

1 and 2 are diagrams showing one embodiment of the waterjet propulsion device of the present invention, with FIG. 1 being a structural diagram thereof and FIG. 2 being an explanatory diagram thereof.

Note that numerals 1 to 7 in FIGS. 1 and 2 refer to the third
Since it is the same as the figure, the explanation will be omitted.

In the above figure, 8 is a flexible elastic body provided at the front lower part of the water intake part 5, 11 is a pressurized chamber formed in the front ship with the flexible elastic body 8 as a rear wall surface,
9 is a pressurizing valve provided in the middle of a pipe 20 that communicates between the pressurizing chamber 11 and the rear of the impeller 1 of the casing 4 in order to pressurize and expand the flexible elastic body 8 from inside, and 10 is a pressurizing valve that is returned to its original state. This is a pressure reducing valve provided in the middle of the pipe 20 that communicates the pressurized chamber 11 and the bottom 7 for this purpose.

Then, the pressurizing chamber 11 and the impeller 1 of the casing 4
A pressure reduction means is provided by a pipe 20 communicating with the rear, a pressurization valve provided in the middle, a pipe 20 communicating between the pressurizing chamber 11 and the bottom 7, and a pressure reduction valve 10 provided in the middle. is formed.

Furthermore, in this embodiment, since the pipe 20 is connected to the rear of the impeller 1 of the casing 4, the flexible elastic body 8 is expanded by the pressure at the outlet of the impeller 1 without any other auxiliary power. ing.

[Effect of idea]

As detailed above, the waterjet propulsion device of the present invention has a flexible elastic body that changes the inclination angle (shape) of the front lower part of the water intake part to the waterjet propulsion device, which conventionally had low speed and low efficiency. This allows efficient operation over a wide speed range.

[Brief explanation of the drawing]

1 and 2 show an embodiment of the waterjet propulsion device of the present invention, with FIG. 1 being a structural diagram thereof and FIG. 2 being an explanatory diagram thereof. Figures 3 to 5 show examples of conventional waterjet propulsors, with Figure 3 showing its structure, and Figures 4 and 5 showing the angle of inclination between the front part of the water intake and the bottom of the ship, and the angle of inclination to the water intake. A schematic diagram for explaining a case where the inflow angles are equal and a case where the inflow angles are different is shown. 1... impeller, 3... nozzle, 5... water intake section,
7... Bottom of the ship, 8... Flexible elastic body, 9... Valve for pressurization, 10... Valve for depressurization, 11... Pressurization chamber, 20... Pipe.

Claims (1)

[Scope of utility model registration request] A water jet that takes in water from a water intake section provided at the bottom of a ship facing forward and downward, and discharges water to the rear of the ship via a nozzle using an impeller installed in a casing connected to the top of the water intake section. In the propulsion device, a flexible elastic body stretched at the front lower part of the water intake part, and a pressurized chamber formed in the front ship with the flexible elastic body as part of the wall surface;
A waterjet propulsion device characterized by comprising a pressurizing/depressurizing means connected to the pressurizing chamber and expanding and contracting the flexible elastic body.