JPH03253492A - Water jet propulsion device - Google Patents

Abstract

PURPOSE:To enhance the propulsion efficiency and reduce the production cost and miniaturize the whole system of a water jet propulsion device by providing a shaft cover inside an intake duct, and providing inside the shaft cover a bearing for supporting a drive shaft. CONSTITUTION:Water A for propulsion taken in an intake duct 2 from an intake hole 11 is allowed to flow smoothly along an inscribing arc 42 extending to below a shaft cover 21, a fundamental circle 40, an inscribing arc 41 extending upward and an inscribing arc 43 of inversed R. A turbulent flow is thus prevented on the lower side of the shaft cover 21 and as a result pump efficiency is enhanced and also propulsion efficiency is enhanced. Because a bearing 23 is provided inside the shaft cover 21, there is no necessity of providing behind an impeller 28 a stator etc., for supporting the impeller 28 and therefore the structure of the water jet propulsion device is simplified so as to reduce the number of parts, thereby reducing the production cost and enhancing the assembling property of the device.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a water jet propulsion device for a small personal watercraft.

(Prior Art) In recent years, small personal watercraft used mainly for leisure purposes are equipped with a water jet propulsion device on the bottom of the stern.
The rotation of an impeller installed in the propulsion channel of this water jet propulsion device sends water for propulsion from the front to the rear, thereby propelling or turning the ship (Japanese Patent Laid-Open No. 62-34898, Tokuko Showa 5
(See Japanese Patent Publication No. 3-21197 and Japanese Patent Publication No. 60-30599).

(Problem to be Solved by the Invention) In a conventional water jet propulsion device, a drive shaft extends in the front-rear direction within the propulsion waterway, and an impeller is rotatably installed in the propulsion waterway at the rear end of the drive shaft. It is being

This drive shaft is not particularly provided with a shaft cover, and the cross section perpendicular to the axis of the drive shaft is circular. Since the propulsion water flows in the propulsion waterway in a direction intersecting the drive shaft, turbulence occurs downstream of the drive shaft, which has a circular cross section. This turbulence adversely affects the smooth flow of propulsion water within the propulsion waterway, reducing propulsion efficiency.

In addition, in conventional water jet propulsion devices, the structure around the impeller is complicated, making it difficult to replace the impeller and requiring a large number of components, resulting in high production costs. As a result, the entire system has become larger.

The present invention has been made in consideration of the above circumstances, and it is possible to improve propulsion efficiency by preventing the generation of turbulent flow due to the drive shaft, and by simplifying the structure around the impeller, it is possible to replace the impeller. It is an object of the present invention to provide a water jet propulsion device that can improve workability, reduce production costs by reducing the number of component parts, and further downsize the entire system.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a propulsion waterway through which water for propulsion passes through the stern of the ship, and connects this propulsion waterway to an intake duct, an impeller housing, and a nozzle in sequence. In a water jet propulsion device, the impeller is rotatably housed in the impeller housing, a drive shaft is provided that extends back and forth within the intake duct, and the impeller is rotatably provided at the rear end of the drive shaft, A shaft cover that surrounds the drive shaft is provided in the intake duct, and a bearing that rotatably supports the rear portion of the drive shaft is provided in the shaft cover.

(Function) Since the shaft cover surrounding the drive shaft is provided in the intake duct, water for propulsion flowing inside the intake duct flows smoothly along the smooth surface of the shaft cup. Therefore, generation of turbulent flow due to the drive shaft can be prevented, and propulsion efficiency can be improved.

In addition, a bearing that rotatably supports the rear part of the drive shaft is installed inside the shaft cover, which simplifies the structure around the impeller and improves the efficiency of impeller replacement.It also reduces production costs by reducing the number of components. As a result, the entire system can be made more compact.

(Example) Hereinafter, an example of a water jet propulsion device according to the present invention will be described with reference to the accompanying drawings.

In the water jet propulsion system, a propulsion channel 1 as shown in FIGS. 1 to 4 is provided at the bottom of the stern of a small personal watercraft. The propulsion waterway 1 is connected to the intake duct 2 from the front side of the hull.
, an impeller housing 3, and a nozzle 4 are sequentially arranged and connected by a long bolt 5. A rudder 6 is attached to the rear of the nozzle 4 so as to be rotatable in the horizontal direction by a pivot bolt 7, and the rudder 6 is rotated left and right by a steering cable 8 to determine the direction of the propulsion water A spouted from the nozzle 4. By changing the direction to the left or right, the ship can be turned.

The intake duct 2 has a top plate 10 extending forward and inclined diagonally downward, and a tip end of the top plate 10 is connected to a bottom plate (not shown) of the hull. An intake port 11 for water A for propulsion is provided on the bottom side of the intake duct 2, and the water A for propulsion taken into the intake duct 2 from this intake port 11 flows along the inclined shape of the top plate 10. Flow diagonally upward, impeller housing 3, nozzle 4
The liquid flows through the interior toward the rear, and is ejected rearward from the rudder 6.

A drive shaft 13 is provided within the waterway of the intake duct 2, passing through the top plate 10 and extending in the front-rear direction. The drive shaft 13 is rotatably supported by a bearing 15 provided on a support portion 14 extending forward from the top plate 10 . The bearing 15 has a bearing 17 that rotatably supports the drive shaft 13. A circlip 18 is interposed in front of the bearing 17, and an oil seal 19 is provided in front of the circlip 18. The front end of the drive shaft 13 is connected to an engine (not shown), and the drive shaft 13 is rotationally driven by the engine.

The drive shaft 13 is located in the water channel of the intake duct 2.
A shaft cover 21 surrounding the shaft is provided.

The lower end line 22 of the shaft cover 21 is formed with a slight slope with respect to the center line of the drive shaft 13 in consideration of die cutting during manufacturing. A bearing 23 is disposed at the rear inside the shaft cover 21, and the rear end of the drive shaft 13 is rotatably supported by the bearing 23. Two bearings 24 are provided on the front side of the bearing 23,
A circlip 25 and an oil seal 26 are provided on the rear side of these bearings 24. A screw 27 is formed at the rear end of the drive shaft 13, and a boss portion 29 of an impeller 28 rotatably housed within the impeller housing 3 is screwed and fixed to the screw 27. A spacer 30 is interposed between the impeller 28 and the bearing 24.

Furthermore, an O-ring 31 is provided between the spacer 30 and the boss portion 29 of the impeller 28.

For example, six rectifying blades 33 are provided within the nozzle 4 as shown in FIG. The straightening blades 33 extend radially,
A cap 34 is disposed at the center of these rectifying blades 33, each of which has a cross-sectional shape as shown in FIG.

The angle formed by each straightening blade 33 is 60 degrees. These straightening blades 33 undo the twist in the rotational direction of the water flow generated by the impeller 28 and eject it rearward.

5 to 7 show the intake duct 2 as a single unit, and the intake duct 2 is integrally provided with a shaft cover 21. As shown in FIG. A through hole 36 for passing the drive shaft 13 is formed in the shaft cover 21, as shown in FIG. The through hole 36 is formed concentrically with the drive shaft 13.

Reference numeral 37 indicates a screw hole through which the bolt 5 is passed.

The cross-sectional shape of the shaft cover 21 perpendicular to the axis is a basic circle 40 concentric with the through hole 36, as shown in FIG. 8(A).
, a tangent arc 41 extending upward from the basic circle 40 , and a tangent arc 42 extending downward from the basic circle 40 . The radii of these tangent arcs 41 and 42 are Ri and R2, respectively. A tangential arc 41 extending upward is connected at its upper part to a tangential arc 43 of an inverted R, and this tangential arc 43 is connected to the top plate 10 . The radius of this inverted R tangent arc 43 is R3.

The shape shown in FIG. 8(A) is the basic shape of the shaft cover 21, and the cross-sectional shape is as shown in FIGS. 8(B) to (E).
As shown in the figure, as you go forward, the drive shaft 1
3 intersects with the top plate 10, so it changes sequentially. That is, the center of the basic circle 40 approaches the top plate 10, and the shape of the basic cross-sectional shape above the part connected to the top plate 10 is lost, and only the shape of the tangential arc 42 extending downward remains. become. A portion projecting upward from the top plate 10 serves as a support portion 14.

In this embodiment, the water A for propulsion taken into the intake duct 2 from the intake port 11 flows through a tangential arc 42 extending downward of the shaft cover 21, a basic circle 40, a tangential arc 41 extending upward, and a tangential arc of an inverted R. It flows smoothly along the arc 43. Therefore, generation of turbulence on the downstream side of the shaft cover 21 can be prevented. As a result, pump efficiency is improved and propulsion efficiency can be improved. That is, compared to the conventional device, the engine horsepower required to achieve the same ship speed may be smaller.

Furthermore, since the bearing 23 is provided inside the shaft cover 21,
There is no need to provide a stator or the like for supporting the impeller 28 behind the impeller 28, and the structure is simplified, reducing the number of parts, reducing costs, and improving ease of assembly.

Furthermore, since the structure around the impeller 28 is simplified, the impeller 28 can be protruded simply by removing the bolts 5, and the workability of replacing the impeller 28 can be improved.

Since there is no need to provide a stator or the like to support the impeller 28, the overall length of the entire system can be shortened to make it more compact, and the space inside the ship can be used more effectively.

9(A), (B) and FIG. 10 show other embodiments of the present invention, in which a fin 45 is provided at the rear lower part of the shaft cover 21. FIG. The fin 45 connects the tangential arc 42 and the lower part of the intake duct 2 by a tangential arc 46 formed of an inverted R. The radius of the tangent arc 46 is R4. The front end of the fin 45 is formed into an inclined shape that becomes downward toward the rear. Further, as shown in the cross-sectional view of FIG. 9(B), the front end portion of the fin 45 is formed into an arc with a radius R5 so that the tip side becomes narrower.

This embodiment also has the same effects as the previous embodiment.

Note that the shaft cover 21 may be formed integrally with the main body of the intake duct 2, or may be formed separately and attached. Further, a grating or the like may be provided at the intake port 11 of the intake duct 2 to prevent foreign matter such as dust from being sucked in.

〔Effect of the invention〕

As explained above, in the present invention, since the shaft cover surrounding the drive shaft is provided in the intake duct, the water for propulsion flowing inside the intake duct flows smoothly along the smooth surface of the shaft cover. Therefore, generation of turbulent flow due to the drive shaft can be prevented, and propulsion efficiency can be improved.

In addition, a bearing that rotatably supports the rear part of the drive shaft is installed inside the shaft cover, which simplifies the structure around the impeller and improves the efficiency of replacing the impeller.It also reduces production costs by reducing the number of components. As a result, the entire system can be made more compact.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of a water jet propulsion device according to the present invention, FIG. 2 is a view taken along the line ■-■ in FIG. 1, and FIG. 3 is a view taken along the line mm in FIG. 1. Arrow view, 4th
The figure is an exploded perspective view showing the above embodiment, FIG. 5 is a vertical sectional view showing the intake duct in the above embodiment as a single item, and FIG.
The figure is Vl-VIX line arrow view 7v! in Fig. 5! J is a view from the ■-■ line in Fig. 5, Fig. 8 (A), (
B), (C). (D) and (E) are respectively A-AX in FIG.
Arrow sectional view, B-BX arrow sectional view, C-CX arrow sectional view, D-DX arrow sectional view and E-EX arrow sectional view, No. 9
Figure (A) is a longitudinal cross-sectional view showing another embodiment of the present invention, Figure 9 (B) is a cross-sectional view taken along the IXB-IXBX arrow in Figure 9 (A), and Figure 10 is a cross-sectional view of Figure 9 (A). FIG. 1... Propulsion waterway, 2... Intake duct, 3...
... Impeller housing, 4... Nozzle, 6... Ladder 10... Top plate, 11... Intake port, 13... Drive shaft, 14... Support part, 15... Bearing,
21...Shaft cover, 23...Bearing, 28...
・Impeller, 29... Boss part, 33... Rectifier blade, 3
4... Cap, 36... Through hole, 40... Basic circle, 41. 42. 43. 46...Tangential arc, 45
···fin.

Claims (1)

[Claims] A propulsion waterway through which water for propulsion passes is provided at the stern, and this propulsion waterway is constructed by sequentially connecting an intake duct, an impeller housing, and a nozzle.The impeller is rotatably housed in the impeller housing, and the interior of the intake duct is In a water jet propulsion device including a drive shaft extending back and forth, and the impeller rotatably provided at the rear end of the drive shaft, a shaft cover surrounding the drive shaft is provided in the intake duct, and the shaft cover surrounding the drive shaft is provided in the intake duct. A water jet propulsion device characterized by being provided with a bearing that rotatably supports the rear part of a drive shaft.