JPH0734795Y2 - Propeller Boss with fins for outboard motors - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a technique for improving the characteristics of a screw propeller often used in, for example, a propulsion device of a ship, and more particularly to a boss portion of the screw propeller. The present invention relates to a propeller boss with fins for outboard motors, in which a rectifying fin is provided in an area excluding a boss cap.

[Conventional technology]

Conventionally, as shown in FIG. 7, a normal screw propeller 1 is constructed by providing a plurality of blades 1B ... around a boss portion 1A, and is attached to a rotary drive propeller shaft 2 via the boss portion 1A. At the same time, the propeller boss cap 3 has a streamlined side view on one end side (usually the rear end side as in this example) of the boss portion in order to minimize the eddy current generated on the downstream side of the boss portion 1A. Are lined up.

Further, in the outboard motor in which the drive mechanism of the screw propeller 4 is provided on the outside of the ship, as shown in FIG. 8, the boss portion 4A expands in the so-called trumpet shape in the downstream direction, and There is also a structure in which exhaust gas is discharged into water from one end (usually the rear end as in this example) of the open boss portion 4A.

[Problems to be solved by the invention]

Thus, for the screw propellers 1 and 4 themselves,
In order to improve the propeller characteristics (especially thruster efficiency), research on design technology regarding the number of blades 1B ..., 4B .. In fact, the limit has been reached, and it is extremely difficult to expect significant improvements in propeller characteristics through research from this point in the future.

By the way, in the propulsion mechanism in which the screw propeller 1 and the propeller boss cap 3 having the above-described configurations are combined, even if it is driven to rotate in a uniform flow, the dotted line in the figure schematically As shown in Fig. 2, the flow around the boss portion 1A of the screw propeller 1 and the flow on the downstream side of the propeller boss cap 3 are considerably disturbed by the presence of the boss portion 1A, and thus the turbulence is generated. The energy loss due to the thing itself is quite large, and in addition, the propulsive force generated by the base end portion of each blade 1B ... close to the boss portion 1A must be small due to the turbulence of the flow, and as a result, It is considered that the problem is that the efficiency of the propulsion device as a whole is considerably reduced.

In particular, when the propulsion mechanism combining the screw propeller 1 and the propeller boss cap 3 is arranged at the stern end of the ship as shown by the imaginary line in the figure, the boss portion 1A of the screw propeller 1 and the propeller boss cap are Three
The problem described above will be further exacerbated, as it will be located in a highly turbulent and large hull wake.

A similar problem can be considered in the case of the outboard motor having the boss portion 4A where the propeller boss cap 3 is not provided.

The present invention has been made in view of the above problems in order to solve the problems, and the purpose thereof is very simple and economically advantageous, but is considerable. A propeller boss with fins for outboard motors that can be expected to have a large effect of improving propeller characteristics (propulsor efficiency) and can further enhance the so-called braking function when stopping the ship by stopping the screw propeller during navigation. To provide.

[Means for solving problems]

In order to achieve the above object, the present invention is provided on the side peripheral surface of the boss portion on the downstream side of the blade of the screw propeller used in the outboard motor and having no boss cap, and the same number of blades for rectifying a plurality of blades. The fins are provided so that the amount of the rectifying fins protruding from the side peripheral surface of the boss portion is 50% or less of the amount of protrusion from the side peripheral surface of the boss portion of the blade, and the fins are formed between the base end portions of the blades. The rectifying fins are provided so as to completely close the gaps around the side peripheral surface of the boss portion when viewed from the rear.

[Action]

The present invention having the above-mentioned structure operates as follows.

That is, since the propeller boss with fins for outboard motors according to the present invention is provided with a plurality of rectifying fins around the propeller boss, as will be more apparent from the description of the embodiments to be described later, the screw The flow around the boss portion of the propeller and the flow on the downstream side of the boss portion are rectified by the presence of the rectifying fins and become a clean flow with little turbulence. Can be suppressed to a very small value, and it becomes possible to generate a larger thrust than the conventional one in the base end portion near the boss portion of each blade of the screw propeller,
Together, these actions result in a significant improvement in overall propeller characteristics (propulsor efficiency). Therefore,
The invention is very effective, especially when applied to screw propellers placed in highly turbulent and large wakes, such as at the stern end of a ship. Further, according to the present invention, it is possible to achieve the characteristic improvement of the screw propeller by adding a slight improvement to the boss portion, rather than realizing the improvement of the screw propeller itself which is extremely difficult and expensive. Therefore, it can be realized extremely easily and economically advantageously.

Furthermore, when stopping the ship by stopping the screw propeller while traveling, each fin acts as a flow resistance against the flow that goes straight backward through the gap between the blade base end parts of the screw propeller that has stopped rotating. It works to further enhance the so-called braking function and acts to stop the ship in a shorter time.

〔Example〕

Hereinafter, the present invention will be described more specifically on the basis of the embodiments shown in the drawings.

First Embodiment Here, FIG. 1 is an overall rear view, FIG. 2 is an overall side view, FIG. 3 is a schematic cross-sectional view of an essential part, and FIG. 4 is a propeller characteristic diagram showing a comparative experiment result.

As shown in FIGS. 1 and 2, a marine screw configured by providing a plurality of (five in this example) skewback type blades 1B ... around the boss portion 1A (see FIG. 2). The propeller 1 is attached to a rotary drive propeller shaft 2 (see FIG. 2) interlockingly connected to an engine (not shown) through the boss portion 1A, and the boss portion 1A.
A propeller boss cap 3 is fixedly provided on the rear end of the propeller shaft 2 so as to be continuous to the rear end side.

Then, on the side peripheral surface of the boss portion 1A between the blades 1B ... And the propeller boss cap 3, a plurality of (5 in this example, correspondingly to the blades 1B ...) rectifying fins X ... It is fixedly installed.

The amount of protrusion from the side peripheral surface of the boss portion 1A of the rectifying fins X ... Is 50% or less of the amount of protrusion from the side peripheral surface of the boss portion 1A of the blade 1B. Effective and desirable. That is, if the protruding amount of the rectifying fins X is too large, the required torque may tend to increase.

Further, as shown schematically in FIG. 3, each of the straightening fins X has a negative end portion Y (hatched portion in FIG. 1) close to the boss portion 1A of the corresponding blade 1B. In order to more effectively control the separation of the flow on the pressure surface, it is arranged so as to form a so-called clearance blade as a whole with respect to the base end portion Y thereof. That is, each blade 1B
The rectifying fins X are provided so as to completely close the gaps around the side peripheral surface of the boss portion formed between the base end portions Y when viewed from the rear.

According to the above configuration, the rectifying fins X are provided by the basic rectifying action of the rectifying fins X provided on the side peripheral surface of the boss portion 1A between the blades 1B ... And the propeller boss cap 3.
The flow on the upstream side and the flow on the downstream side of not only are rectified so as to be a clean flow with little turbulence, but also the rectifying fins X are connected to the base end portions Y of the blades 1B of the propeller 1 as described above. By arranging so as to form the clearance blades, the flow separation that has been apt to occur conventionally on the suction surface side of the base end portions Y of the blades 1B ... (It is schematically shown by the dotted line in FIG. 3). The energy loss due to the turbulence of the flow can be extremely reduced, and a large thrust force is applied to the base end portion Y ... of the blade 1B of the screw propeller 1 near the boss portion 1A. Can be generated.

In addition, when stopping the ship by stopping the screw propeller during traveling, each fin will flow for all of the flow that goes straight backward through the gap between the blade base end parts of the screw propeller that has stopped rotating. By acting as a resistance, the so-called braking function can be further enhanced, and the ship can be stopped in a shorter time.

FIG. 4 shows the propeller independent test result in the case of the screw propeller 1 with the rectifying fins X ... and the independent test result in the case of the same screw propeller 1 not having the rectifying fins X. It is a propeller characteristic figure compared.

As is clear from this, in the case of the propeller boss with fins according to the present invention, the thrust coefficient _KT increases while the torque coefficient _KQ decreases while the propeller boss with the same screw propeller 1 is used. A significant improvement in efficiency η of about 1.5% has been achieved. However, since this is the result of a propeller independent test in a uniform flow, even when the performance is extremely disturbed, such as at the stern end of a ship, and when placed in a large ship wake, even greater performance is expected. It can be expected to improve.

Second Embodiment Here, FIG. 5 is an overall rear view and FIG. 6 is an overall side view.

As shown in FIGS. 5 and 6, a marine screw configured by providing a plurality of (three in this example) skew-back type blades 4B ... around the boss portion 4A (see FIG. 6). The propeller 4 is attached to a rotary drive propeller shaft 5 (see FIG. 6) interlockingly connected to an engine (not shown) via the boss portion 4A.

Unlike the first embodiment, a boss cap is not provided on the rear end side of the boss portion 4A which is the downstream side of the blades 4B ... And the boss portion 4A has a so-called trumpet shape on the rear end side. The structure is such that the exhaust gas is discharged into the water from the rear end.

A plurality of rectifying fins X ... (three in this example, corresponding to the blades 4B ...) Are fixedly provided on the side peripheral surface of the boss portion 4A on the downstream side of the blades 4B. ing.

The amount of protrusion from the side peripheral surface of the boss portion 4A of the rectifying fins X ... Is 50% or less of the amount of protrusion from the side peripheral surface of the boss portion 4A of the blade 4B. Effective and desirable. That is, if the protruding amount of the rectifying fins X is too large, the required torque may tend to increase.

In addition, each of the rectifying fins X is the third fin of the first embodiment.
Similar to the case schematically shown in the figure, the flow separation on the suction surface of the base end portion Y (the portion shown by hatching in FIG. 5) near the boss portion 4A of the corresponding blade 4B is more effective. So that it can be controlled in a controlled manner, it is arranged so as to form a so-called clearance blade as a whole with respect to the base end portion Y thereof. That is, the rectifying fins X are provided so as to completely close the respective gaps around the side peripheral surface of the boss portion formed between the base end portions Y of the blades 4B in a rear view.

According to the above configuration, the boss portion 4A on the downstream side of the blades 4B ...
By the basic rectifying action of the rectifying fins X ... Provided on the side peripheral surface of the rectifying fins, the flow on the upstream side and the downstream side of the rectifying fins X ... is rectified so as to be a clean flow with little turbulence. However, as described above, the rectifying fins X ... Are arranged so as to form the clearance blades with respect to the base end portions Y ... of the blades 4B ... of the propeller 4, so that the base end portions Y ... of the blades 4B. The flow separation (similar to what is schematically shown by the dotted line in FIG. 3) that has been apt to occur conventionally on the negative pressure side can be suppressed very effectively,
Therefore, the energy loss due to the turbulence of the flow can be made extremely small, and the blades 4B of the screw propeller 4 ...
It is possible to generate a large thrust also at the base end portion Y ... Near the boss portion 4A.

In addition, when stopping the ship by stopping the screw propeller during traveling, each fin will flow for all of the flow that goes straight backward through the gap between the blade base end parts of the screw propeller that has stopped rotating. By acting as a resistance, the so-called braking function can be further enhanced, and the ship can be stopped in a shorter time.

It should be noted that this invention is not limited to the above-mentioned embodiment, and it goes without saying that various modifications can be made without departing from the spirit of this invention.

For example, in the first and second embodiments, the rectifying fins X
The shape of ... May be a simple thin plate shape, but if it has a blade cross-sectional shape capable of generating a positive lift as shown in FIG. It is more desirable because it can generate thrust.

[Effect of device]

As is clear from the above description, according to the propeller boss with fins for outboard motors according to the present invention, by adopting a means of providing a plurality of rectifying fins on the side peripheral surface of the boss portion of the screw propeller. The flow around the boss portion of the screw propeller and the flow downstream of the boss portion can be rectified into a clean flow with little turbulence.

Therefore, it is possible to suppress the energy loss due to the turbulence of the flow, which has occurred conventionally, to a very small level, and it is possible to generate a large thrust at the base end portion near each boss portion of each blade of the screw propeller as compared with the conventional case. . Therefore, overall propeller characteristics (propulsor efficiency)
Can be significantly improved, and can be applied very effectively particularly when the screw propeller is arranged in a very disturbed and large wake such as at the stern end of a ship.

In addition, according to the present invention, it is possible to sufficiently improve the propeller characteristics by the extremely simple and economically advantageous improvement of the boss portion without making the extremely difficult and expensive improvement of the screw propeller itself. You can

Furthermore, when stopping the ship by stopping the screw propeller during traveling, each rectification so as to completely close the gaps around the side peripheral surface of the boss portion formed between the base end portions of each blade in rear view. Since the fins are provided, each fin acts to block all of the flow that goes straight backward through the gap between the blade base end parts of the screw propeller that has stopped rotating, and each fin acts as a base end for each blade. It acts as a resistance to all of the flow that goes straight backward after passing through the partial gap, so that the so-called braking function can be further enhanced and the ship can be stopped in a shorter time, which is a very practical and beneficial effect. Is played.

[Brief description of drawings]

1 to 4 show a first embodiment of a propeller boss with fins for outboard motors according to the present invention. FIG. 1 is an overall rear view, FIG. 2 is an overall side view, and FIG. FIG. 4 is a schematic cross-sectional view of the main part, and FIG. 4 is a propeller characteristic diagram showing the results of comparative experiments. 5 and 6 show a second embodiment of a propeller boss with fins for outboard motors according to the present invention. FIG. 5 is an overall rear view and FIG. 6 is an overall side view. 7 and 8 show a conventional technique. FIG. 7 is an overall side view of a propeller boss cap, and FIG. 8 is an overall side view of an outboard motor. [Explanation of symbols] 1,4 …… Screw propeller 1A, 4A …… Boss part 1B, 4B …… Blade 3 …… Propeller boss cap X …… Rectifying fin

Claims (1)

[Scope of utility model registration request] 1. A boss portion side having a same number of rectifying fins as the blade is provided on the side peripheral surface of the boss portion downstream of the blade of a screw propeller used in an outboard motor and having no boss cap. The amount of protrusion of the rectifying fins from the peripheral surface is set to 50% or less of the amount of protrusion from the side peripheral surface of the boss portion of the blade, and around the side peripheral surface of the boss portion formed between the base end portions of each blade. The propeller boss with fins for outboard motors, characterized in that each rectifying fin is provided so as to completely close each of the gaps when viewed from the rear.