JPH0738077Y2 - Ship propeller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a propeller, which is a propeller of a ship.

<Prior Art> A propeller of a ship is composed of blades and a boss for fixing the blades to a shaft, and the number of blades is usually 3 to 4. The stern side of the blade is a part of the screw around the axis of rotation or a shape close to it, and each cross section of the screw has an angle of attack to the flow, and when the blade is rotated, it acts on the pressure surface. The pressure is higher than the pressure on the back,
The water is pushed around the back of the propeller and the reaction allows the ship to move forward.

<Problems to be solved by the invention> In recent years, ship owners such as fish boats have particularly demanded that the engine be left as it is and that only the propeller be improved to increase the speed. This is because it wants to reach the target place as soon as possible than other ships.

In order to meet such a demand, it is possible to consider increasing the deployment area ratio of the propeller and increasing the angle of attack of the pitch surface, but in this case, the correlation with the engine characteristics is delicate. However, in this case, not only is it expensive, but also damage to the propeller is expected due to obstacles, floating objects, mishandling, etc. Also, if the angle of attack of the screw is increased too much to increase the thrust, or if the number of rotations is increased too much, the pressure on the back surface of the blades generally decreases to the vapor pressure of water, and cavitation easily occurs. It was far from an effective means.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a propeller capable of further increasing the speed.

<Means for solving the problem> This invention focuses on the fact that the side slip loss of water is usually about 15 to 18% on the pressure surface of the blade due to the rotation of the propeller, and this side slip loss must be eliminated. As a result of various studies on the measures to be taken, the invention was finally completed. That is, of the pressure surface of the blade, the length from the center to the tip in the radial direction and about 1/3 of the arc length from the front edge to the rear edge of the blade centered on the axis of the boss in the width direction. A plurality of guide ridges with a substantially triangular cross-section with the pressure side as the bottom are within the range from the start point to the end point of the rear edge, with the start point being the point closer to the rear edge side from the front edge. Are arranged side by side in the radial direction, and the starting side of each guiding ridge is a pointed end, and the size of the guiding ridge is gradually increased from the pointed end to the end of the end point. Has achieved the purpose of.

<Embodiment> Referring to FIG. 1 showing a perspective view of an embodiment of the present invention and FIG. 2 which is a front view thereof, this ship propeller also has three blades 1 and one blade 1. It is composed of a boss 2 for fixing to the shaft, 1a indicates a front edge where water circulates from a low pressure back surface to a high pressure pressure surface when the blade 1 rotates, and 1b indicates a rear end edge on the opposite side. . As is clear from the figure, in the pressure surface of each blade 1, a little from the front edge 1a between the base of the blade 1 to the approximate center of the blade 1 and the approximate distance from the center of the blade 1 to the tip. There is nothing different from the conventional part. However, in the remaining part, that is, from the center to the tip in the radial direction,
Further, in the width direction, the front end edge 1a is shifted from the front end edge 1a to the rear end edge 1b by a length corresponding to about 1/3 of the arc length from the front end edge 1a to the rear end edge 1b of the blade 1 with the axis of the boss 2 as the center. A plurality of elongated guiding ridges 3 are provided side by side in the width direction of the blade 1 in a plurality of illustrated examples within a range from the starting point to the ending point of the rear edge 1b. The individual guiding ridges 3 are
The front end edge 1a side is formed as a pointed end 3a, and the pointed end 3a gradually increases in size and extends to the terminal end 3b, forming a mountain range having a substantially triangular cross section.

Therefore, when the propeller rotates, the water around the pressure surface of the blade 1 is automatically guided between the tip ends 3a, 3a of some guide ridges 3 and gradually increases from the tip end 3a to the terminal end 3b. The guide ridges 3 having a high height prevent side slippage of water, and the trailing edge 1b of the blade 1 has a plurality of guide ridges 3.
Since the outlet area is substantially narrowed by the water, the water guided between the guiding ridges 3 is squeezed to accelerate the speed, and the water thus accelerated is transferred to the rear edge 1b of the blade 1. Will be released from.

<Advantages of the Invention> With the above-described configuration of the invention, side slip loss of water due to propeller rotation is improved, and as a result, speedup is achieved. This can also be confirmed from the following experimental results conducted on a recreational fishing boat with a displacement of 3.12 tons, an engine of 190 horsepower, and an engine speed of 2600 rpm. That is,
The propeller originally attached to this recreational fishing boat had a diameter of 700 mm,
The pitch was 760 mm and the deployment area ratio was 55%, but in making the propeller to be devised, the diameter and pitch of the propeller were the same as before, and the deployment area ratio was intentionally reduced by 10% to 45%. As a result, the experimental result shows that the speed increased by about 1.2 knots, even though the rotation speed decreased by about 100 rotations, and everything else was the same as the conventional one. In this way, speeding up reduces the deployment area ratio of the propeller. In other words, the effect of this invention, which can be produced at such a low price, is extremely large in practical use.

Further, although the above example is the case of a fish boat, when the propeller according to the present invention is put into practical use and applied to a work boat with a rotation of 1000 rpm or less, improvement of propulsion capability can be expected.

[Brief description of drawings]

FIG. 1 is a perspective view of a blade of a propeller for a ship according to the present invention seen from the front side, and FIG. 2 is a front view thereof. 1 ... blade, 1a ... front edge, 1b ... rear edge, 2 ... boss, 3 ... guide ridge body, 3a ... pointed tip, 3b ... end.

Claims (1)

[Scope of utility model registration request] 1. A ship propeller comprising a blade (1) and a boss (2) for fixing the blade (1) to a shaft, wherein the pressure surface of the blade (1) is substantially central in the radial direction. From the front to the tip, and in the width direction with the axis of the boss (2) as the center, the front edge (1a) or the rear edge (1b) of the blade (1).
From the start point to the end point of the rear edge (1b), the point near the front edge (1a) to the rear edge (1b) by about 1/3 of the arc length up to Within the range, a plurality of guide ridges (3) having a substantially triangular cross-section with the pressure side as the bottom are provided side by side in the radial direction, and the starting point side of each guide ridge (3) is the pointed end (3a). The propeller for a ship, characterized in that the size of the guiding ridge (3) is gradually increased from the pointed end (3a) to the terminal end (3b).