JPS626891A - Propeller protecting device - Google Patents

Abstract

PURPOSE:To inhibit ice blocks from entering into a propeller stream, by providing, on the outer skin of the stern of a ship, a screen-like protecting member extending rearward from the outer skin to at least a position just before a propeller, having a diameter larger than that of the outer periphery of the propeller at the position. CONSTITUTION:The front section of a protecting member 4 composed of a plurality of fins 41, 41... is secured to a stern section 1 by means of welding, etc. This protecting member 4 extends rearward to a position jut before a propeller 3, and is attached at its trailing edge section with a propeller protecting duct 5. If the space between each adjacent fins 41, 41 is set to have a size equal to the size of ice blocks which are allowed to enter into the propeller stream, ice blocks having a size exceeding the allowable size passes through the outside of the enclosure of the protecting member 4 and emerges into the propeller wash by way of the outer periphery of dust. With this arrangement is is possible to prevent ice pieces from entering into the propeller wash. Further, it is possible to restrain the flow resistance as far as possible.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Object of the Invention (Field of Industrial Application) The present invention is utilized in the technical field of ocean-going vessels, and particularly relates to a device for protecting a propeller from ice fragments.

(Prior art) When a broken ice fragment collides with a propeller while a ship is navigating underwater, a large so-called ice torque acts, which can cause damage to the propeller, trouble with the variable pitch mechanism, and
This in turn causes failure in the equiaxial bearing system. Moreover, even without the above-mentioned damage, the ice-breaking ability of the ship will be significantly reduced due to the decrease in propeller thrust. In order to avoid such troubles, devices have been devised that minimize the interference between the propeller and the ice chips, as shown in FIGS. 3 to 6 of the accompanying drawings.

First, in the case shown in FIG. 3, plate-shaped protectors 101 and 102 are provided that protrude downward from the bottom of the ship and extend to the vicinity of the propeller 100 on both sides of the propeller, so that wood chips flowing under the bottom of the ship are protected from both sides of the propeller 100. Excluded from the outside.

In the one shown in Fig. 4, a plurality of fins 103, 103... are attached to the outer plate in front of the propeller 100, and the pitch between the fins is set to such an extent that ice pieces larger than a certain size cannot enter. ing. Therefore, ice chips flow outside the fins and do not reach the propeller.

However, even with the two conventional types mentioned above, the propeller is not completely protected from the wood chips, and if anything, the ice chips that have gotten around the propeller can become clogged without flowing out backwards, resulting in reduced thrust. A situation arises in which the amount decreases.

In addition, in addition to the above-mentioned two sides, the hull is not provided with any special additions, but is provided with a concave portion 104 that is greatly recessed upward, with the shape of the hull facing the direction of the propeller 100, as shown in FIG. There is also known a type in which the propeller floats above the propeller 100 while flowing backward. However, this type of system reduces the effective space in the hull, and cannot be applied to existing hulls.

Furthermore, there is also known a propeller with a duct, as shown in FIG. 6, in which a lattice 106 is provided on the front surface of the duct 105. Although this type of propeller can reliably prevent ice chips from flowing into the propeller 100, it receives resistance from the front lattice portion, resulting in increased fluid resistance and is also prone to clogging with ice chips.

As described above, conventional devices cannot be expected to be perfect, and improvements have been desired.

(Problems to be Solved by the Invention) The present invention solves the problems of the conventional device described above, reliably prevents ice chips from flowing into the propeller flow, and does not increase fluid resistance. Providing propeller protection devices.

(2) Structure of the Invention (Means and Effects for Solving the Problems) In order to solve the above-mentioned problems, the present invention includes a protective member configured as follows at the stern part of the outer plate. There is.

The protective member has a screen shape and extends rearward from the outer panel,
It reaches at least a position directly in front of the propeller, and is larger than the outer circumference of the propeller at this position. The protective member may be, for example, a plurality of fins arranged substantially along streamlines or a plurality of bars arranged on a circumference larger than the propeller outer circumference, at least at the propeller position portion.

The pitch interval between the fins or between the bar members is set to a size that allows the ice pieces to flow into the propeller flow.

The protective member may have its rear end located just in front of the propeller, or may extend to the rear of the propeller and have its rear end converge. Furthermore, in the case of a propeller with a duct, it is also possible to fix it to the duct.

Note that, in order to keep the fluid resistance as low as possible, it is preferable that the envelope outer shape of the protective member is along a streamline.

According to the device of the present invention as described above, ice chips are prevented from permeating into the protective member, and are flowed along the outside of the protective member, so that they do not suddenly flow into the propeller flow from the side immediately before the propeller. It disappears.

(Example) Hereinafter, the present invention will be described in detail based on the accompanying drawings FIGS. 1 and 2.

FIG. 1 shows a first embodiment. In the figure, reference numeral 1 indicates a stern portion, from which a propeller shaft 2 projects rearward, and a propeller 3 is attached to the rear end of the propeller shaft 2. The front part of a protection member 4 consisting of a plurality of fins 41, 41, etc. is fixed to the stern part 1 by welding or the like, and the protection member 4 extends rearward to a position just in front of the propeller, and its rear edge portion A duct 5 for protecting the propeller is attached to the propeller.

Each fin 41 constituting the protection member 4 has an airfoil shape to reduce fluid resistance, and its width gradually increases as shown in FIG. 1(B). It extends to the outer periphery, and its planar shape is almost triangular.

In this embodiment having such a protection member 4, if the interval between each fin 41, 41, and the earth is set to the size of the ice pieces that are allowed to flow into the propeller flow, Ice pieces exceeding the allowable value flow around the outer side of the protective member 4 and flow into the duct 5.
It passes through the outer circumference of the jet and merges into the wake of the propeller. Thus, no ice chips enter the propeller flow of ice chips. Moreover, fluid resistance can be suppressed to the lowest possible level.

Note that this embodiment can be implemented as is even if the duct 5 is removed.

Next, a second embodiment shown in FIG. 2 will be described.

In this embodiment, the protection member 6 is made of a bar material forming a porridge instead of a fin.

In the stern part 1, a plurality of bar materials 61, 61 and 61 are arranged at a set pitch.
The front end of ... is fixed by welding, etc.

The spacing between the bar members 61, 61, . . . is determined in the same manner as the spacing between the fins in the previous embodiment.

The bar members 61, 61, . . . have their rear ends distributed and fixed around the outer periphery of the duct 5. However, the protection member 6 has a horizontally elongated cage shape with its respective bar members 61, 61, .

In addition, in order to prevent ice chips from flowing in from the rear when the ship retreats or the propeller reverses, each of the above bar materials oL 61... is extended to the rear of the duct as shown by the two-dot chain line in Figure 2. , and the envelope shape may be converged to reduce fluid resistance, forming a cage shape closed at the rear.

Although the above two embodiments have been described with respect to an axle propeller, it goes without saying that the present invention can also be applied to a ship with a two-wheeled propeller.

(3) Effects of the Invention As described above, the present invention can completely prevent wood chips from flowing into the propeller flow using the protective member, so it is possible to completely prevent wood chips from flowing into the propeller flow. It is possible to completely eliminate this trouble and also prevent a decrease in thrust.

Furthermore, the protective member does not increase fluid resistance compared to conventional protective members. In this way, it will greatly contribute to both reducing the accident rate and maintaining performance during ocean navigation.

[Brief explanation of drawings]

FIG. 1 shows a first embodiment of the present invention, FIG. 1A is a partially cutaway front view, FIG. 1B is a plan view, FIG. 2C is a side view, and FIG. A partially broken front view showing the second embodiment,
3 to 6 are perspective views showing each conventional device. 1... Stern section 3... Propeller 4... Protection member 41... Fin 5... ...Duct 6 ...Protection member 61 ...Bar material patent applicant Nihon Kokan Co., Ltd. Representative Patent attorney Takashi Fujioka Figure 4

Claims (5)

[Claims] (1) Propeller protection with a screen-shaped protective member whose front part is fixed to the stern part of the outer plate and whose rear part extends at least to a position just in front of the propeller, and which is larger than the outer circumference of the propeller at that position. Device. (2) The propeller protection device according to claim (1), wherein the rear or middle portion of the protection member is connected to a propeller duct. (3) The propeller protection device according to claim (1) or (2), wherein the protection member is a plurality of parallel fins. (4) The protective member is characterized in that at least the propeller position portion is a plurality of bar members arranged on a circumference larger than the outer circumference of the propeller. ) Propeller protection device described in section 2. (5) The propeller protection device according to any one of claims (1) to (4), wherein the protection member extends to the rear of the propeller and converges.