JPH01122797A - Water jet pusher - Google Patents

Abstract

PURPOSE:To equalize the direction of flow velocity in the inlet and outlet of a fixed blade so as to reduce the length and the number of leaves of the blade by arranging an inducer and a main impeller on the same axis and as well constructing them to rotate in opposite directions. CONSTITUTION:An inducer 5 and a main impeller 6 are arranged on the same axis along the water flow direction in a casing 4. The inducer 5 and the main impeller 6 are respectively fixed to a hollow shaft 7 and the top of a center shaft 8 connected to a drive shaft 12, and a fixed blade 9 is arranged in the front of the flow direction of the main impeller 6. A reversal device 13 is provided on the base end portion of the hollow shaft 7 and the center shaft 8, and this reversal device 13 is composed of a sun gear 14 fixed to the enter shaft 8, an internal gear 15 which is carved on the inner circumferential surface of a large diameter portion connected integrally to the base end of the hollow shaft 7, an intermediate gear 16 arranged in such a way to be engaged with each other between both gears 14, 15 and a fixed link 17 which supports the intermediate gear 16 as not to rotate.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a water jet propulsion device used as a propulsion device for a high-speed ship, and particularly to an improvement of the pump section thereof.

(Prior art) As shown in FIG. 4, the water jet propulsion device described above is
Water sucked in from the bottom of the ship is pressurized by a pump 2 connected to a driving machine 1, and is injected from a nozzle 3 at the stern to obtain thrust.

For this pump, a mixed flow pump with an inducer is generally used due to demands for high efficiency, high speed, and miniaturization. In ultra-high-speed ships of the 60-knot class or less, a system was generally adopted in which the inducer and the main impeller were separated, and the inducer was rotated at a lower speed than the main impeller in the same direction.

That is, as shown in FIG. 5, an inducer 5 and a main impeller 6 are disposed coaxially along the water flow direction inside the casing 4, and the inducer 5 and main impeller 6 are connected to the hollow shaft 7 and the center. The hollow shaft 7 and the central shaft 8 are configured to rotate in the same direction via the drive machine 1 shown in FIG. 4, and the hollow shaft 7 is rotated at a lower speed than the central shaft 8. A first fixed blade W9a was arranged between the inducer 5 and the main impeller 6, and a second fixed blade 9b was arranged in front of the main impeller 6 in the flow direction.

Note that 10 is 1 between the casing 4 and the hollow shaft 7.
1 is a water sealing device interposed between the hollow shaft 7 and the central shaft 8, respectively.

Then, the absolute speed is v1, the circumferential speed of the fixed blade is U1, the relative speed between the two is W1, and the subscripts a, b...f are at the positions shown in Figure 5.The speed triangle is as shown in the upper part of Figure 3. become.

(Problem to be solved by the invention) However, in the above conventional example, the inducer 5
Since the direction of the absolute velocity V5 at the exit of the main impeller 6 is different from the direction of the absolute velocity V of the population of the main impeller 6, the first fixed blade 9a is interposed between the two to change the direction of the absolute velocity V of the exit of the main impeller 6. Since it is necessary to match the direction of the absolute speed V of

In addition, the first fixed g9a functions to change the direction of the water flowing out from the inducer 5 with a velocity component in the circumferential direction in the axial direction and send it out to the main impeller 6, but the process of changing the flow direction However, there is a problem in that it causes a loss in the pump, which causes a decrease in the overall pump efficiency.

It is possible to design one of the two fixed wings as a non-working wing, but this would increase the load on the other fixed wing and the overall effect of the fixed wing would be reduced. does not change.

In view of the above, an object of the present invention is to provide a blade that reduces the length and number of blades by reducing the functions shared by fixed blades, and achieves higher efficiency, smaller size, and lighter weight. .

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a water jet propulsion device that generates thrust by pressurizing water sucked in from the bottom of a ship using a pump and injecting it from a nozzle at the stern. The inducer and the main impeller are arranged coaxially, and the inducer and the main impeller are configured to rotate in opposite directions.

(Function) By making the directions of the circumferential speed of the inducer and the circumferential speed of the main impeller opposite to each other, the directions of the flow velocities at the inlet and outlet of the fixed blade are made equal, thereby increasing the length of the blade, The number, thickness, etc. are set to the minimum values necessary for structural strength, and may be omitted in some cases.

(Embodiment) Figures 1 to 2 show an embodiment of the present invention, in which an inducer 5 and a main impeller 6 are disposed coaxially along the water flow direction inside the casing 4. 5 is fixed to a hollow shaft 7, and the main impeller 6 is fixed to the tip of a central shaft 8 connected to a drive shaft 12. Fixed blades 9 are arranged in front of the main impeller 6 in the flow direction.

A reversing device 13 is provided at the starting ends of the hollow shaft 7 and the central shaft 8. This reversing device 13 includes a sun gear 14 fixed to the central shaft 8, an internal gear 15 carved on the inner peripheral surface of a large diameter portion integrally connected to the starting end of the hollow shaft 7, and the sun gear 14. It is comprised of an intermediate gear 16 disposed in mesh with the internal gear 15, and a fixed link 17 that supports the intermediate gear 16 in a non-rotatable manner.

Therefore, when the diameter of the sun gear 14 is R□ and the diameter of the internal gear 15 is R2, the internal gear 15 is rotated in the opposite direction of the sun gear 14 at a speed ratio of R/R2, thereby driving. The main impeller 6 is rotated as the shaft 13 rotates, and at the same time, the inducer 5 is rotated by being decelerated in the opposite force direction to the main impeller 6 at a speed ratio of R1/R2 via the reversing device 13. .

Note that 10 is 1 between the casing 4 and the hollow shaft 7.
1 is a water sealing device interposed between the hollow shaft 7 and the central shaft 8, respectively.

The lower part of FIG. 3 shows the velocity triangle of this embodiment, which corresponds to the above-mentioned conventional example, and as shown here, the inducer 5
By making the directions of the circumferential speeds Ua, U5 and the circumferential speeds Ud, Ue of the main impeller 6 opposite to each other, the absolute velocity Vb at the outlet of the inducer 5 and the absolute velocity V at the inlet of the main impeller 6,
The blade angle of the main impeller inlet can be determined so that the directions of The length has been shortened to make it smaller and lighter. Furthermore, since there is no fixed blade loss between the inducer 5 and the main impeller 6, the overall efficiency of the pump is increased.

Furthermore, in the velocity triangle at the outlet of the main impeller 6, the direction of the absolute velocity V 1 at the outlet of the main impeller 6 can be directed in the axial direction vf by appropriately selecting the blade outlet angle.

Therefore, the fixed vanes 9 can be made into idle vanes that only rectify the flow that is slightly twisted in the radial direction when the operating point of the pump deviates from the design point. It can be made substantially straight and radial in shape compared to a curved wing, making it lighter, smaller and more efficient.

(Effect of the invention) Since the present invention has the above configuration, the length of the fixed blade,
The number of sheets can be significantly reduced or omitted, and therefore, it is possible to significantly reduce size, weight, and efficiency compared to conventional devices.

[Brief explanation of the drawing]

Figures 1 and 2 show an embodiment of the present invention, with Figure 1 being a front sectional view, Figure 2 being a schematic side view showing the reversing device, and Figure 3 showing a velocity triangle at a representative point of the flow path. FIG. 4 is a schematic front view of a ship equipped with a water jet propulsion device, and FIG. 5 is a view corresponding to FIG. 1 showing the conventional example. 1...Driver, 2...Pump, 3...Nozzle, 5
... Inducer, 6 ... Main impeller, 7 ... Hollow shaft, 8 ... Central shaft, 9 ... Fixed blade, 13 ... Reversing device, 14 ... Sun gear, 15. ...Internal gear. Applicant's agent Yu Sato Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] In a water jet propulsion device that generates thrust by pressurizing water sucked in from the bottom of the ship using a pump and injecting it from a nozzle at the stern, an inducer and a main impeller are arranged coaxially, and the inducer and main impeller are arranged on the same axis. A water jet propulsion device configured to rotate in opposite directions.