JPH0744559Y2 - Marine propeller with boss cap - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to an improvement in a marine propeller, and more particularly to a marine propeller in which a boss cap attached to a rear end of a propeller boss is improved.

[Conventional technology]

A conventional marine propeller with a boss cap is shown in FIG. 5 (side view).
A propeller boss 3 is fixed to the rear end of the propeller shaft 2 rotatably penetrating the inside of the propeller boss 3. A plurality of propeller blades 4 are radially provided on the outer peripheral surface of the propeller boss 3. There is.

A boss cap 5 is provided on the rear end of the propeller boss 3 by being joined.

When the propeller configured as described above is rotated by a main engine (not shown) and the hull is traveling forward, a vortex is generated on the surface of the propeller boss 3 and flows backward, and the trailing edge of the boss cap 5 Immediately after that, a large number of vortex flow molecules are merged, and a large vortex flow A is generated as shown in FIG.

Due to the generation of the vortex flow A, a backward force is generated based on the negative pressure, so that an action of reducing the thrust generated from the propeller blades 4 is performed, which causes a decrease in propeller propulsion efficiency. There is.

Therefore, in order to prevent the generation of a large eddy current A, as shown in FIGS. 3 and 4, fins 6 radially protruding on the boss cap 5 are attached in the same number as the propeller blades 4. The mounting angle θ _F is different from the mounting angle θ _P of the propeller blade as shown in FIG.

Then, by the action of the fins 6, the molecules of the vortex generated on the surface of the propeller boss 3 are diffused, thereby preventing the generation of the vortex behind the boss cap 5 and preventing the propeller propelling efficiency from decreasing. It has become.

[Problems to be solved by the device]

By the way, in the conventional marine propeller with the boss cap having the fins 6 as described above, the molecules of the eddy current generated on the surface of the propeller boss 3 flow substantially parallel to each other along the blade root portion of the propeller blade 4. A certain angle of attack is generated for the fin 6 having a mounting angle θ _F different from the mounting angle θ _P of the blade root portion of the propeller blade 4. Therefore, fin 6
Since a force in the direction opposite to the thrust generated by the propeller blades 4 is generated, the thrust is reduced, and the propulsion efficiency of the propeller is reduced accordingly.

The present invention is intended to solve such a problem, and is provided with fins capable of preventing the generation of a large swirl behind the boss cap,
By making it possible to prevent the rearward generation of force by the fins themselves, the propeller propulsion efficiency is improved.
An object is to provide a marine propeller with a boss cap.

[Means for Solving the Problems]

In order to achieve the above-mentioned object, the marine propeller with a boss cap of the present invention comprises a propeller boss having a plurality of propeller blades and a boss cap provided at the rear end of the propeller boss. A plurality of fins projecting from the same surface to a height substantially corresponding to the root portion of the propeller blade is provided, and the mounting angle of the fin is the same as the mounting angle at the blade root portion of the propeller blade, and It is characterized in that the trailing edge portion is formed by bending toward the back side of the propeller blade.

[Action]

In the above-described marine propeller with the boss cap of the present invention, the flow on the propeller boss surface along the blade root of the propeller blade flows parallel to the fins on the boss cap, and the vortex generated on the propeller boss surface causes The curved trailing edge diffuses and prevents the formation of large eddies at the rear end of the boss cap.

Further, since the rear edge portion of the fin is configured to be bent toward the back surface side of the propeller blade, the generation of backward force by the fin itself as in the conventional case is reduced.

〔Example〕

Referring to the drawings, a marine propeller equipped with a boss cap as an embodiment of the present invention will be described below. FIG. 1 is a side view thereof, and FIG. 2 is a plan view showing in detail essential parts thereof.

As shown in FIGS. 1 and 2, also in the case of the marine propeller with the boss cap of the present invention, the propeller boss 3 is fixed to the rear end of the propeller shaft 2 rotatably penetrating the inside of the stern bossing 1. Then, on the outer peripheral surface of the same propeller boss 3,
A plurality of propeller blades 4 are radially provided.

Further, on the surface of the boss cap 5, a plurality of fins 7 (as many as the propeller blades 4) radially protruding from the surface are provided up to a height substantially corresponding to the blade root portion of the propeller blade 4.

In this invention the boss marine propeller cap, as shown in FIG. 2, in particular the mounting angle theta _F of the fin 7 is a propeller blade 4
Is equal to the attachment angle θ _{P at} the blade root portion, and the trailing edge portion of the fin 7 is formed by bending toward the back surface side of the propeller blade 4.

When the marine propeller configured as described above is forwardly rotated by a main machine (not shown), vortex molecules generated on the surface of the propeller boss 3 are diffused by the action of the bent trailing edge of the fin 7, so that the boss cap 5 It is possible to prevent a large eddy current from being generated at the rear end, and it is possible to prevent the generation of a backward force due to the negative pressure of the vortex. Therefore, the thrust is increased and the propulsion efficiency is improved as compared with the case where a large eddy current (see reference numeral A in FIG. 5) is generated as in the conventional case.

In addition, the flow on the surface of the propeller boss 3 is
Because the flow along the blade root portion substantially parallel, becomes substantially parallel with respect to the fins 7 with the same setting angle theta _F and the mounting angle theta _P of the blade root portion, so too is no angle of attack, the fin Since the drag of itself is not generated, and therefore the force in the opposite direction to the thrust (the force in the backward direction) is not generated, the thrust of the propeller is further increased as compared with the case with the conventional fin,
This will greatly improve the propeller propulsion efficiency.

[Effect of device]

As described in detail above, according to the marine propeller with the boss cap of the present invention, the mounting angle of the fins provided on the boss cap is made the same as the mounting angle at the blade root portion of the propeller blade to prevent an increase in resistance due to the fins themselves. However, it is possible to prevent the generation of a large eddy current behind the boss cap by the action of the trailing edge portion of the fin that is bent to the rear side of the propeller blade. Compared with the case, it has the effect of further improving the propeller propulsion efficiency.

[Brief description of drawings]

1 and 2 show a marine propeller with a boss cap as an embodiment of the present invention. FIG. 1 is a side view thereof, and FIG.
The figure is a plan view showing the main part in detail, and FIGS. 3 and 4 show a conventional marine propeller with a boss cap.
FIG. 4 is a side view thereof, FIG. 4 is a plan view showing in detail its essential parts, and FIG. 5 is a side view showing the operation of another example of a conventional marine propeller with a boss cap. 1 ... stern bossing, 2 ... propeller shaft, 3 ... propeller boss, 4 ... propeller blade, 5 ... boss cap, 6,
7 ... Fin, A ... Eddy current.

Claims (1)

[Scope of utility model registration request] 1. A propeller boss having a plurality of propeller blades, and a boss cap provided at a rear end of the propeller boss, the surface of the boss cap substantially corresponding to the root portion of the propeller blade from the same surface. A plurality of fins protruding to the height are provided, the mounting angle of the fins is made equal to the mounting angle at the blade root portion of the propeller blade, and the trailing edge portion of the fin is bent toward the back side of the propeller blade. A marine propeller with a boss cap, which is characterized by being formed as follows.