JP6246960B1 - Ship propulsion device and ship - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the propulsion performance while suppressing the occurrence of cavitation and erosion in a ship propulsion device and a ship. A port propeller shaft 21 and a starboard propeller shaft 22, a port propeller 23 and a starboard propeller 24, a port shaft bracket 25 and a starboard shaft bracket 26, a port rudder 27 and a starboard rudder 28, and a center skeg 29 are provided. The forward / backward distance between the propeller shafts 21 and 22 protruding from the stern 13 to the outside and the center P2 of the propellers 23 and 24 is L1, and the propellers 23 and 24 are moved forward from the center P2 to L1 / 2. When the width at the lowermost position of the center skeg 29 at the intermediate position P3 is b1, and the width of the center skeg 29 at the height of the axial center positions O1 and O2 of the propeller shafts 21 and 22 at the intermediate position P3 is b2. b1 ≦ b2 is set. [Selection] Figure 1

Description

  The present invention relates to a marine vessel propulsion apparatus including two propeller shafts and a center skeg, and a marine vessel equipped with the marine vessel propulsion apparatus.

  A general marine vessel propulsion device uses a main machine to rotate the propeller to obtain propulsive force. In a single-shaft vessel equipped with one main machine and one propeller, the ship will increase its size and act on one propeller. In order to increase the degree of load to be applied and obtain a sufficient propulsive force, it is necessary to increase the rotation speed of the propeller or increase the diameter of the propeller. Then, since the peripheral speed of the propeller increases, cavitation, which is a phenomenon in which bubbles near the propeller blade tip drop and bubbles are generated in the water, may occur excessively. When cavitation occurs, the hull vibrates through the stern bottom. Further, erosion may occur in the propeller due to cavitation, which adversely affects the durability of the propeller.

  Therefore, it is known to apply a biaxial ship having two main engines and two propellers. In a twin-screw ship, the load degree of one propeller is reduced, the propeller efficiency is improved, and the occurrence of cavitation can be suppressed. As a propulsion device for a biaxial ship, there are an overlapping propeller (OLP) system and an interlock propeller system. As such a marine vessel propulsion apparatus, there are those described in Patent Documents 1 and 2 below.

JP 2011-098678 A Japanese Patent Laid-Open No. 2006-097687

  However, in the propulsion device using the above-described OLP method, the propeller disposed at the rear alternately alternates between a fast flow accelerated by the front propeller during one rotation and a slow flow near the center in the width direction of the ship. pass. Therefore, the load applied to the propeller blades of the rear propeller varies greatly. As a result, the biaxial ship using the OLP system may have an excessive bearing force acting on the bearing of the propeller shaft of the rear propeller, as compared with the single screw ship. In addition, in the twin-screw ship using the OLP system, a high-speed rotational flow is newly formed by the rotation of the front propeller, so the rear propeller needs to operate in a very complicated flow. The range where cavitation occurs increases. Then, excessive vibration may occur. Further, when tip vortex cavitation is generated from the tip of the propeller blade of the front propeller, the generated bubbles may burst on the propeller blade surface of the rear propeller, and may cause erosion of the propeller blade.

  On the other hand, in a propulsion device using an interlock propeller system, the rotation of both propellers must be controlled so that the wings of one propeller and the other propeller do not interfere with each other, making rotation control difficult. . And if the wing | blade of one propeller and the wing | blade of the other propeller interfere, each propeller will be damaged.

  The present invention solves the above-described problems, and an object thereof is to provide a marine vessel propulsion device and a marine vessel that improve the propulsion performance while suppressing the occurrence of cavitation and erosion.

  In order to achieve the above object, a marine vessel propulsion device according to the present invention includes a port propeller shaft and a starboard propeller shaft that are supported at a stern along the longitudinal direction of the hull and rotatably at a predetermined interval in the width direction of the hull. A port propeller and a starboard propeller that are respectively fixed to axial ends of the port propeller shaft and the starboard propeller shaft, and a stern provided on the stern for rotatably supporting the port propeller shaft and the starboard propeller shaft. A port shaft bracket and a starboard shaft bracket, a rudder disposed behind the hull from the port propeller and the starboard propeller, and a skeg disposed on the bottom of the ship between the port propeller shaft and the starboard propeller shaft. The port side propeller shaft and the starboard propeller shaft L1 is a front-to-back distance from the stern projecting outside to the center of the port propeller and starboard propeller, and the skew at the center position of the port propeller and the center of the starboard propeller is L1 / 2 forward. B1 ≦ b2 where b1 is the width at the lowest end position of the seg and b2 is the width of the skeg at the axial position of the starboard propeller shaft and the starboard propeller shaft at the intermediate position. It is what.

  Therefore, by setting the width of the skeg to the lowermost position and setting the width to be the same or narrow, the water flow rising on both sides of the skeg flows smoothly without being interrupted by the skeg, reducing the hull resistance and propeller. Propulsion performance can be improved by efficiently collecting the upward flow in the vicinity of the center position in the ship width direction W in the plane.

  In the marine vessel propulsion device according to the present invention, the skeg is provided with a bulging portion wider than the width b1 and the width b2 between the lowermost position and the axial position at the intermediate position. Yes.

  Therefore, the water flow that rises on both sides of the skeg flows smoothly along the bulging part without being interrupted by the skeg, and the hull resistance is reduced while the hull resistance is reduced in the vicinity of the center position in the ship width direction W. The upward flow can be efficiently collected to improve the propulsion performance.

  In the marine vessel propulsion apparatus of the present invention, when the diameters of the port propeller and the starboard propeller are Dp, the shortest distance d between the tip of the port propeller and the tip of the starboard propeller on the center side in the width direction of the hull is , 0 <d ≦ 0.2Dp.

  Therefore, the port propeller and starboard propeller are arranged close to the center side in the width direction of the hull, and the upward flow at the center portion in the width direction can be efficiently collected, and the propulsion performance can be improved. Further, the port propeller and the starboard propeller do not interfere with each other unlike the interlock propeller system, and the hull can be easily manufactured. By placing the port propeller and starboard propeller in parallel, risks such as excessive bearing force, expansion of the cavitation range, and occurrence of erosion in the rear propeller can be significantly suppressed as compared with the OLP method.

  In the marine vessel propulsion device of the present invention, the rotation directions of the port propeller and the starboard propeller are inwardly rotating from the outside of the hull toward the center in the width direction at the upper part of the port propeller and the starboard propeller. It is characterized by being set.

  Therefore, the port propeller and the starboard propeller can efficiently collect the upward flow in a region overlapping the region where the upward flow is generated, and can further improve the propulsion performance.

  In the marine vessel propulsion device according to the present invention, the port propeller shaft and the starboard propeller shaft are set such that the distance between the axial centers increases toward the rear of the hull.

  Therefore, the main engine for rotating the port propeller and starboard propeller can be installed on the center side in the width direction of the hull, and the stern can be leaned, and hull resistance can be reduced.

  In the marine vessel propulsion device of the present invention, the port propeller shaft and the starboard propeller shaft are set such that the height from the ship bottom to the shaft center decreases toward the rear of the hull.

  Accordingly, the height from the main engine and the ship bottom for rotating the port propeller and starboard propeller can be increased, the stern can be made thinner, and the hull resistance can be reduced.

  In the marine vessel propulsion device according to the present invention, when the diameters of the port propeller and the starboard propeller are Dp, the center of the port propeller and the center of the starboard propeller at the axial positions of the port propeller shaft and the starboard propeller shaft. A distance L2 to the front edge of the rudder is set to 0 <L2 ≦ 1.0Dp.

  Therefore, the leading edges of the port propeller and starboard propeller can be brought close to the rudder, the wake from the port propeller and starboard propeller can be reliably applied to the rudder surface, and the steering effect and propulsion performance can be improved.

  Moreover, the ship of this invention is provided with the propulsion apparatus of the said ship.

  Accordingly, it is possible to improve the propulsion performance by efficiently collecting the upward flow in the vicinity of the center position in the ship width direction W in the propeller plane while reducing the hull resistance.

  According to the marine vessel propulsion device and the marine vessel of the present invention, it is possible to improve the propulsion performance by efficiently collecting the upward flow in the vicinity of the center position in the width direction W in the propeller plane while reducing the hull resistance. it can.

FIG. 1 is a side view showing a stern to which a marine vessel propulsion device according to the first embodiment is mounted. FIG. 2 is a plan view showing a stern to which a ship propulsion device is mounted. 3 is a cross-sectional view taken along the line III-III in FIG. 4 is a cross-sectional view taken along the line IV-IV in FIG. FIG. 5 is a graph showing a propulsion performance index with respect to the distance between propeller tips / propeller diameter. FIG. 6 is a graph showing the required horsepower with respect to the ship speed. FIG. 7 is a schematic diagram showing a stern to which the marine vessel propulsion device according to the second embodiment is mounted. FIG. 8 is a side view showing a stern to which the marine vessel propulsion device according to the third embodiment is mounted. FIG. 9 is a plan view showing a stern to which a ship propulsion device is mounted. FIG. 10 is a plan view showing a stern to which the marine vessel propulsion device according to the fourth embodiment is mounted.

  Exemplary embodiments of a marine vessel propulsion apparatus and a marine vessel according to the present invention will be explained below in detail with reference to the accompanying drawings. In addition, this invention is not limited by this embodiment, and when there are two or more embodiments, what comprises combining each embodiment is also included.

[First Embodiment]
1 is a side view showing a stern equipped with a boat propulsion device according to the first embodiment, FIG. 2 is a plan view showing a stern equipped with a boat propulsion device, and FIG. III sectional drawing and FIG. 4 are IV-IV sectional drawings of FIG.

  In the first embodiment, as shown in FIGS. 1 and 2, the ship 11 is a biaxial ship, and a propulsion device 14 is mounted on the stern 13 of the hull 12. The propulsion device 14 includes a port propeller shaft 21 and a starboard propeller shaft 22, a port propeller 23 and a starboard propeller 24, a port shaft shaft bracket 25 and a starboard shaft bracket 26, a port rudder 27 and a starboard rudder 28, and a center skeg 29. It has.

  Here, the ship 11 can be moved forward and backward by the propulsion device 14, the direction in which the ship 11 moves forward is referred to as the front F of the hull 12, and the direction in which the ship 11 moves back is referred to as the rear R of the hull 12. A direction parallel to the front F and the rear R of 12 is referred to as a ship length direction L of the hull 12. The horizontal direction of the hull 12 orthogonal to the front F and rear R of the hull 12 is referred to as a ship width direction W, and the vertical direction of the hull 12 orthogonal to the front F and rear R of the hull 12 is referred to as a ship height direction H.

  The hull 12 has a shape in which the rear side is curved upward from the bottom 15 (baseline BL) toward the rear R, and a stern 13 is provided. Further, the hull 12 has a shape in which the rear side of the center portion in the width direction W is curved upward from the ship bottom 15 toward the rear R at the position of the rear R of the stern 13, and a center skeg 29 is provided. A left rudder 27 and a right rudder 28 are respectively provided on both sides of the center skeg 29 at the stern 13.

  The port propeller 23 is provided below the port side of the bottom 15 of the stern 13. The port propeller 23 is connected to one end of the port propeller shaft 21 in the axial direction. The hull 12 is provided with a port main engine (for example, a diesel engine) 31 inside the port side. The portside propeller shaft 21 is inserted into the hull 12 through the stern tube 32 provided on the bottom 15 of the other end in the axial direction, and is connected to the port side main engine 31. Therefore, the port main machine 31 can rotate the port propeller 23 via the port propeller shaft 21.

  The starboard propeller 24 is provided below the starboard side of the bottom 15 of the stern 13. The starboard propeller 24 is connected to one end of the starboard propeller shaft 22 in the axial direction. The hull 12 is provided with a starboard main engine (for example, a diesel engine) 33 inside the starboard side. The starboard propeller shaft 22 is inserted into the hull 12 through the stern tube 34 provided at the bottom 15 of the other end in the axial direction, and is connected to the starboard main machine 33. Therefore, the starboard main machine 33 can rotate the starboard propeller 24 via the starboard propeller shaft 22.

  The port side propeller shaft 21 is supported by a port side shaft bracket 25 so that its rear end protruding outward from the hull 12 from the stern tube 32 is in front of the port side propeller 23. Further, the starboard propeller shaft 22 has a rear end portion protruding outward from the hull 12 from the stern tube 34 and is rotatably supported by a starboard shaft bracket 26 in front of the starboard propeller 24. As shown in FIG. 3, the shaft brackets 25 and 26 are provided with cylindrical support portions 25a and 26a that rotatably support the propeller shafts 21 and 22, respectively, and V upwards from the cylindrical support portions 25a and 26a. It is composed of a plurality of (two in this embodiment) struts 25b, 25c, 26b, and 26c that extend in a letter shape and are connected to the stern 13 at the upper end.

  As shown in FIGS. 1 and 2, the port side propeller shaft 21 and the starboard propeller shaft 22 are set so that the distance between the axial centers increases toward the rear R. That is, the port propeller shaft 21 is disposed so as to be inclined toward the direction away from the center position C in the ship width direction W (the port side) as the axial center position O1 goes rearward R. Further, the starboard propeller shaft 22 is disposed so as to be inclined toward the direction (starboard side) away from the center position C in the ship width direction W as the axial center position O2 goes rearward R. The port propeller shaft 21 and the starboard propeller shaft 22 are set so that the height from the ship bottom 15 to the axial center positions O1 and O2 decreases toward the rear R. That is, the port propeller shaft 21 and the starboard propeller shaft 22 are disposed to be inclined toward the bottom 15 as the axial center positions O1 and O2 go to the rear R.

  In this embodiment, as shown in FIGS. 1 and 4, the position P1 at which the port propeller shaft 21 and starboard propeller shaft 22 protrude outward from the stern 13 (the hull 12) and the center P2 of the port propeller 23 and starboard propeller 24 are shown. The front-to-back distance to is L1. Further, the width at the lowermost position of the center skeg 29 at the intermediate position P3 shifted from the center P2 of the port propeller 23 and the center P2 of the starboard propeller 24 to the front F by L1 / 2 is defined as b1. Furthermore, the width of the center skeg 29 at the height of the axial center positions O1 and O2 of the port propeller shaft 21 and the starboard propeller shaft 22 at the intermediate position P3 is defined as b2. In this case, at the intermediate position P3, the lowermost position of the center skeg 29 and the axial positions O1, O2 of the port side propeller shaft 21 and the starboard propeller shaft 22 are at a height h. At this time, b1 ≦ b2 is set.

  That is, the center skeg 29 has a shape in which the rear side of the center portion in the ship width direction W of the ship bottom 15 extends in the horizontal direction and curves upward toward the rear R from the middle. Here, the center skeg 29 has an inflection position from a horizontal plane along the ship bottom 15 to a curved surface curved upward toward the rear R, from the center P2 of the port propeller 23 and the center P2 of the starboard propeller 24 to L1 / 2. It is provided in a region up to the intermediate position P3 that has shifted to the front F only. Further, the center skeg 29 has a tapered shape whose width decreases from the lower surface of the stern 13 downward in the ship height direction H (thickness in the ship width direction W decreases). That is, the center skeg 29 has a horizontal horizontal plane that intersects with the inclined surfaces 29a and 29b along the ship length direction L whose lower side approaches the center position C side with respect to the ship height direction H and the lower ends of the inclined surfaces 29a and 29b. 29c. Employing the center skeg 29 having such a shape improves the propulsion performance by efficiently collecting the upward flow in the vicinity of the center position C in the ship width direction W in the propeller plane while reducing the hull resistance. be able to.

  The center skeg 29 has a tapered shape by setting b1 <b2. However, the center skeg 29 may have the same width shape downward from the lower surface of the stern 13 by setting b1 = b2. In this case, the inclined surfaces 29a and 29b are vertical surfaces. In addition, a curved surface may be provided at the intersection of each inclined surface 29a, 29b and the horizontal surface 29c. In this case, the width b1 at the lowermost position of the center skeg 29 is the distance between each inclined surface 29a, 29b and the curved surface. The width of the inflection position.

  Further, as shown in FIG. 3, the port propeller 23 and the starboard propeller 24 are arranged symmetrically with respect to the center position C in the ship width direction W with a distance that does not interfere with each other. That is, the ship 11 of the present embodiment is not an OLP method or an interlock propeller method, but a method in which the port propeller 23 and the starboard propeller 24 are arranged in parallel in the ship width direction W.

  That is, the propeller diameters of the port side propeller 23 and the starboard propeller 24 are Dp. Further, d is the shortest distance (distance between propeller chips) between the tip of the port propeller 23 and the tip of the starboard propeller 24 on the center position C side in the ship width direction W. At this time, 0 <d ≦ 0.5 Dp, preferably 0 <d ≦ 0.2 Dp. Here, the propeller diameters Dp of the port propeller 23 and the starboard propeller 24 are the rotation diameters at the outermost peripheral position when the port propeller 23 and the starboard propeller 24 are rotated. The distance d between the propeller tips is such that there is no possibility of contact between the propeller blades of the port propeller 23 and the starboard propeller 24, and the port propeller 23 and the starboard propeller 24 are centered in the ship width direction W so that an upward flow can be captured. It is preferable to set it as small as possible so that it can be arranged as close as possible to the position C.

  Specifically, since the ship 11 of the present embodiment is a system in which the port propeller 23 and the starboard propeller 24 are arranged in parallel, the distance d between the propeller chips is larger than 0 m, preferably 0.1 m or more. Is good. This is to prevent the port propeller 23 and starboard propeller 24 from interfering with each other even when processing errors and assembly errors are taken into account. The distance d between the propeller chips is preferably set to 1.0 m or less, more preferably 0.5 m or less. This is because by reducing the distance d between the propeller chips as much as possible, the vertical vortex near the center position C in the ship width direction W can be captured and the propulsion performance can be further improved. Further, the distance d between the propeller chips may be equal to or greater than the maximum thickness of the left rudder 27 and the right rudder 28.

  FIG. 5 is a graph showing a propulsion performance index with respect to the distance between propeller tips / propeller diameter.

  In FIG. 5, the horizontal axis represents the distance between propeller chips / propeller diameter between the port propeller 23 and the starboard propeller 24, and the vertical axis represents the propulsion performance index of the ship 11. A normalized value assuming that the propulsion performance in the case of a biaxial ship propelled by the main engine is 1.0 is shown. Here, the propulsion performance is horsepower performance, and the smaller the horsepower required to produce the same speed, the better the performance, that is, the fuel economy performance. Therefore, the propulsion performance is better as the numerical value of the propulsion performance index on the vertical axis is smaller, and the propulsion performance is worse as the numerical value is larger. As can be seen from the graph of FIG. 5, in order to improve the propulsion performance, the propulsion performance needs to be 1.0 or less, and the distance between propeller tips / propeller diameter is 0.5 or less, preferably 0. It should be set to 2 or less.

  Further, as shown in FIG. 3, an upward flow as indicated by a dotted line is generated in a region between the port propeller 23 and the starboard propeller 24. In order to improve the propulsion performance by efficiently collecting this upward flow, in this embodiment, the rotation direction of the port propeller 23 and starboard propeller 24 is set in the ship width direction W above the port propeller 23 and starboard propeller 24. The inner rotations R1 and R2 rotate from the outside toward the center position C side. The port side propeller 23 and the starboard propeller 24 can efficiently collect the upward flow in the range of the region overlapping the vertical vortex generation region. As the distance d between the propeller chips is reduced, the upward flow can be efficiently recovered and the propulsion performance can be further improved.

  In addition, the heights of the axial center positions O1 and O2 of the port propeller 23 and the starboard propeller 24 are preferably the same positions in consideration of the maneuverability of the ship 11, but need not be the same positions.

  Further, as shown in FIG. 2, the port rudder 27 and the starboard rudder 28 are rearward Rs of the portside propeller 23 and the starboard propeller 24, and are axial positions of the portside propeller 23 and the starboard propeller 24 in the plan view of the hull 12. Although it is preferable to be provided on O1 and O2, it may be provided closer to the center of the hull than on the axial positions O1 and O2. The port rudder 27 and starboard rudder 28 are wing cross-sectional shapes, supported by a rudder shaft (not shown) that extends vertically downward from the stern 13, and rotate around the vertical axis to change the course direction.

  Here, it is preferable that the port rudder 27 and the starboard rudder 28 have the front edge, the port propeller 23, and the starboard propeller 24 as close as possible. This is because the fast flow generated by the port propeller 23 and starboard propeller 24 flows into the port rudder 27 and starboard rudder 28, and the steering effect is improved. Specifically, the propeller diameters of the port side propeller 23 and the starboard propeller 24 are Dp. Further, the distance from the center P2 of the port propeller 23 and the center P2 of the starboard propeller 24 to the front edge of the port rudder 27 and starboard rudder 28 at the axial center positions of the port propeller shaft 21 and the starboard propeller shaft 22 is L2. At this time, 0 <L2 ≦ 1.0 Dp is set.

  As described above, in the marine vessel propulsion device according to the first embodiment, the port propeller shaft 21 and the starboard propeller shaft 22, the port propeller 23 and the starboard propeller 24, the port shaft shaft bracket 25 and the starboard shaft bracket 26, and the port rudder. 27 and starboard rudder 28, and a center skeg 29, each propeller shaft 21 and 22 is projected to the outside from the stern 13 to a position P1 and the center P2 of each propeller 23, 24 is L1, and each propeller 23 24, the width at the lowermost position of the center skeg 29 at the intermediate position P3 shifted from the center P2 to the L1 / 2 front is b1, and the heights of the axial positions O1 and O2 of the propeller shafts 21 and 22 at the intermediate position P3. When the width of the center skeg at b2 is set to b2, b1 ≦ b2.

  Therefore, by setting the center skeg 29 to the lowermost position and setting the width to be the same or narrower, the water flow rising on both sides of the center skeg 29 flows smoothly without being disturbed by the center skeg 29, and the hull resistance The propulsion performance can be improved by efficiently collecting the upward flow in the vicinity of the center position C in the ship width direction W within the propeller plane. That is, as shown in FIG. 6, the required horsepower with respect to the boat speed can be reduced as compared with the prior art.

  In the marine vessel propulsion apparatus of the first embodiment, when the diameter of each propeller 23, 24 is Dp, the shortest distance d between the front end of each propeller 23, 24 on the center position C side in the ship width direction W of the hull 12 is , 0 <d ≦ 0.2Dp. Therefore, the port propeller 23 and the starboard propeller 24 are arranged close to the center position C side in the ship width direction W of the hull 12, and the upward flow in the vicinity of the center position C in the ship width direction W is efficiently recovered. The propulsion performance can be improved. Further, the port propeller 23 and the starboard propeller 24 do not interfere with each other unlike the interlock propeller system, and the hull 12 can be easily manufactured. By arranging the port propeller 23 and the starboard propeller 24 in parallel, risks such as excessive bearing force in the rear propeller, expansion of the cavitation range, and occurrence of erosion can be significantly suppressed as compared with the OLP method.

  In the marine vessel propulsion device according to the first embodiment, the rotation direction of each propeller 23, 24 is an inward rotation that rotates from the outside of the hull 12 toward the center position C in the width direction W at the top of each propeller 23, 24. Is set. Therefore, the port propeller 23 and the starboard propeller 24 can efficiently collect the upward flow in the region overlapping the vertical vortex generation region, and can further improve the propulsion performance.

  In the marine vessel propulsion device of the first embodiment, the distance between the axial centers of the port propeller shaft 21 and the starboard propeller shaft 22 is set so as to increase toward the rear R of the hull 12. Accordingly, the main engines 31 and 33 for rotating the port propeller 23 and the starboard propeller 24 can be installed on the center position C side in the width direction W of the hull 12, and the stern 13 can be thinned, and the hull resistance is increased. Can be reduced.

  In the marine vessel propulsion device of the first embodiment, the port propeller shaft 21 and starboard propeller shaft 22 are set so that the height from the bottom 15 to the axial positions O1 and O2 decreases toward the rear R of the hull 12. Yes. Accordingly, the height from the main engine 31, 33 for rotating the port propeller 23 and the starboard propeller 24 and the bottom 15 can be increased, the stern 13 can be thinned, and the hull resistance can be reduced. .

  In the marine vessel propulsion device according to the first embodiment, when the diameter of each propeller 23, 24 is Dp, each rudder 27 from the center P2 of each propeller 23, 24 at the axial position O1, O2 of each propeller shaft 21, 22 is provided. , 28 is set to 0 <L2 ≦ 1.0 Dp. Accordingly, the front edges of the port propeller 23 and starboard propeller 24 can be brought close to the port rudder 27 and starboard rudder 28, and the wake from the port propeller 23 and starboard propeller 24 can be reliably applied to the control surface, and the steering effect is improved. And propulsion performance can be improved.

  Moreover, in the ship of 1st Embodiment, the propulsion apparatus 14 of the ship 11 is provided. Accordingly, it is possible to improve the propulsion performance by efficiently collecting the upward flow in the vicinity of the center position C in the ship width direction W within the propeller plane while reducing the hull resistance.

[Second Embodiment]
FIG. 7 is a schematic diagram showing a stern to which the marine vessel propulsion device according to the second embodiment is mounted. The basic configuration of the marine vessel propulsion apparatus of the present embodiment is substantially the same as that of the first embodiment described above, and will be described with reference to FIGS. 1 and 2 and the first embodiment described above. Members having similar functions are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the second embodiment, as shown in FIGS. 1, 2, and 7, the propulsion device 14 includes a port propeller shaft 21 and a starboard propeller shaft 22, a port propeller 23 and a starboard propeller 24, a port shaft bracket 25, and a starboard. A shaft bracket 26, a left rudder 27 and a right rudder 28, and a center skeg 41 are provided.

  The hull 12 has a shape in which the rear side is curved upward from the bottom 15 toward the rear R, and a stern 13 is provided. Further, the hull 12 has a shape in which the rear side of the center portion in the width direction W is curved upward from the bottom 15 toward the rear R at the position of the rear R of the stern 13, and a center skeg 41 is provided. Further, a port rudder 27 and a star rudder 28 are provided on both sides of the center skeg 41 at the stern 13 respectively.

  As shown in FIGS. 1 and 7, the front-to-rear distance from the position P1 where the port propeller shaft 21 and starboard propeller shaft 22 project outward from the stern 13 (the hull 12) to the center P2 of the port propeller 23 and starboard propeller 24 is represented by L1. And Further, the width at the lowermost position of the center skeg 41 at the intermediate position P3 shifted from the center P2 of the port propeller 23 and the center P2 of the starboard propeller 24 to the front F by L1 / 2 is defined as b1. Furthermore, the width of the center skeg 41 at the height of the axial center positions O1 and O2 of the starboard propeller shaft 21 and the starboard propeller shaft 22 at the intermediate position P3 is b2. In this case, at the intermediate position P3, the lowermost position of the center skeg 41 and the axial positions O1 and O2 of the starboard propeller shaft 21 and the starboard propeller shaft 22 have a height h. At this time, b1 ≦ b2 is set.

  That is, the center skeg 41 has a shape in which the rear side of the center portion in the ship width direction W of the ship bottom 15 extends in the horizontal direction and curves upward toward the rear R from the middle. Further, the center skeg 41 decreases in width from the lower surface of the stern 13 downward in the ship height direction H (becomes thicker in the ship width direction W) and then becomes smaller (in the ship width direction W). It has a bulging taper shape (thickness is reduced). That is, the center skeg 41 is provided below the first curved surfaces 41a and 41b and the first curved surfaces 41a and 41b along the ship length direction L, the lower side of which is separated from the center position C side with respect to the ship height direction H. Bulging portions 41c and 41d extending in the ship length direction L projecting outward, second curved surfaces 41e and 41f along the ship length direction L approaching the center position C side downward from the bulging portions 41c and 41d, and a second curve It is comprised from the horizontal level surface 41g which cross | intersects at the lower end part of the surfaces 41e and 41f. By adopting the center skeg 41 having such a shape, the propulsion performance is improved by efficiently collecting the upward flow in the vicinity of the center position C in the ship width direction W in the propeller plane while reducing the hull resistance. be able to.

  In this case, the center skeg 41 is provided with bulging portions 41c and 41d having a width b1 and a width b3 wider than the width b2 between the lowermost position and the axial positions O1 and O2 at the intermediate position P3. . The center skeg 41 has a tapered shape by setting b1 <b2, but by setting b1 = b2, the lower part of the second curved surfaces 41e and 41f is directed downward to have the same width shape. Good.

  As described above, in the marine vessel propulsion apparatus according to the second embodiment, the center skeg 41 has a width wider than the width b1 and the width b2 between the lowest end position and the axial positions O1 and O2 at the intermediate position P3. B3 bulge portions 41c and 41d are provided.

  Therefore, the water flow rising on both sides of the center skeg 41 flows smoothly along the bulging portions 41c and 41d without being disturbed by the center skeg 41, and the ship width direction W in the propeller plane is reduced while reducing the hull resistance. As a result, the upward flow in the vicinity of the center position C can be efficiently recovered to improve the propulsion performance.

[Third Embodiment]
FIG. 8 is a side view showing a stern to which a boat propulsion device according to the third embodiment is mounted, and FIG. 9 is a plan view showing the stern to which a boat propulsion device is mounted. In addition, the same code | symbol is attached | subjected to the member which has the same function as embodiment mentioned above, and detailed description is abbreviate | omitted.

  In the third embodiment, as shown in FIGS. 8 and 9, the propulsion device 14 includes a port propeller shaft 21 and a starboard propeller shaft 22, a port propeller 23 and a starboard propeller 24, a port shaft shaft bracket 25, and a starboard shaft bracket 26. And a starboard intermediate shaft bracket 51 and a starboard intermediate shaft bracket 52, a port rudder 27 and a starboard rudder 28, and a center skeg 29.

  The port propeller 23 is provided below the port side of the bottom 15 of the stern 13 and is connected to one end of the port propeller shaft 21 in the axial direction. The other end of the port propeller shaft 21 is inserted through the stern tube 32 into the hull 12 and connected to the port main engine 31. On the other hand, the starboard propeller 24 is provided below the starboard side of the bottom 15 of the stern 13 and is connected to one end of the starboard propeller shaft 22 in the axial direction. The starboard propeller shaft 22 is inserted into the hull 12 through the stern tube 34 at the other end in the axial direction and connected to the starboard main engine 33.

  The port side propeller shaft 21 is supported by a port side shaft bracket 25 so that its rear end protruding outward from the hull 12 from the stern tube 32 is in front of the port side propeller 23. The starboard propeller shaft 22 has a rear end portion that protrudes outward from the hull 12 from the stern tube 32 and is rotatably supported by a starboard shaft bracket 26 in front of the starboard propeller 24. Further, the port propeller shaft 21 is rotatably supported by a port intermediate shaft bracket 51 at an intermediate portion protruding outward from the hull 12 from the stern tube 32. Further, the starboard propeller shaft 22 is rotatably supported by a starboard intermediate shaft bracket 52 at an intermediate portion protruding outward from the hull 12 from the stern tube 32. The intermediate shaft brackets 51 and 52 have cylindrical support portions 51a and 52a that rotatably support the propeller shafts 21 and 22, and upper ends that extend upward from the cylindrical support portions 51a and 52a in a V shape. Is composed of a plurality of (two in this embodiment) struts 51b, 51c, 52b, 52c connected to the stern 13.

  As described above, in the marine vessel propulsion apparatus according to the third embodiment, the rear end portions of the propeller shafts 21 and 22 are supported on the hull 12 by the shaft brackets 25 and 26, and the middle of the propeller shafts 21 and 22. The part is supported on the hull 12 by the intermediate shaft brackets 51 and 52. Accordingly, the support rigidity of each propeller shaft 21 and 22 can be increased.

[Fourth Embodiment]
FIG. 10 is a plan view showing a stern to which the marine vessel propulsion device according to the fourth embodiment is mounted. In addition, the same code | symbol is attached | subjected to the member which has the same function as embodiment mentioned above, and detailed description is abbreviate | omitted.

  In the fourth embodiment, as shown in FIG. 10, the propulsion device 14 includes a port propeller shaft 21 and a starboard propeller shaft 22, a port propeller 23 and a starboard propeller 24, a port shaft shaft bracket 25 and a starboard shaft bracket 26, and a port port. An intermediate shaft bracket 53 and a starboard intermediate shaft bracket 54, a left rudder 27 and a starboard rudder 28, and a center skeg 29 are provided.

  The port propeller 23 is provided below the port side of the bottom 15 of the stern 13 and is connected to one end of the port propeller shaft 21 in the axial direction. The other end of the port propeller shaft 21 is inserted through the stern tube 32 into the hull 12 and connected to the port main engine 31. On the other hand, the starboard propeller 24 is provided below the starboard side of the bottom 15 of the stern 13 and is connected to one end of the starboard propeller shaft 22 in the axial direction. The starboard propeller shaft 22 is inserted into the hull 12 through the stern tube 34 at the other end in the axial direction and connected to the starboard main engine 33.

  The port side propeller shaft 21 is supported by a port side shaft bracket 25 so that its rear end protruding outward from the hull 12 from the stern tube 32 is in front of the port side propeller 23. The starboard propeller shaft 22 has a rear end portion that protrudes outward from the hull 12 from the stern tube 32 and is rotatably supported by a starboard shaft bracket 26 in front of the starboard propeller 24. Further, the port propeller shaft 21 is rotatably supported by a port intermediate shaft bracket 53 at an intermediate portion protruding outward from the hull 12 from the stern tube 32. The starboard propeller shaft 22 is rotatably supported by a starboard intermediate shaft bracket 54 at an intermediate portion protruding outward from the hull 12 from the stern tube 32. The intermediate shaft brackets 53 and 54 have cylindrical support portions 53 a and 54 a that rotatably support the propeller shafts 21 and 22, and extend upward from the cylindrical support portions 53 a and 54 a so that the upper ends thereof extend to the stern 13. It is comprised from the one strut 53b and 54b connected.

  In this case, the single struts 53b and 54b may be the shape of the struts 51b and 52b of the second embodiment or the shape of the struts 51c and 52c, and the vertical direction from the cylindrical support portions 53a and 54a. It may have a shape that extends straight to the upper end and is connected to the stern 13, or a shape that extends straight from the cylindrical support portions 53 a and 54 a in the lateral direction or the oblique direction and the tip is connected to the center skeg 29. It is good.

  As described above, in the marine vessel propulsion device of the fourth embodiment, the rear end portions of the propeller shafts 21 and 22 are supported on the hull 12 by the shaft brackets 25 and 26, and the middle of the propeller shafts 21 and 22 is provided. The portion is supported on the hull 12 by the intermediate shaft brackets 53 and 54. Accordingly, the support rigidity of each propeller shaft 21 and 22 can be increased. Further, the structure can be simplified by using one strut 53b, 54b for the cylindrical support portions 53a, 54a.

11 ship 12 hull 13 stern 14 propulsion device 15 ship bottom 21 port propeller shaft 22 starboard propeller shaft 23 starboard propeller 24 starboard propeller 25 port shaft shaft bracket 26 starboard shaft bracket 27 port rudder 28 starboard rudder 29, 41 center skeg (skeg)
31 Port main engine 32, 34 Stern tube 33 Starboard main engine 51, 53 Port intermediate shaft bracket 52, 54 Star port intermediate shaft bracket

Claims (19)

A port propeller shaft and a starboard propeller shaft that are supported along the stern along the longitudinal direction of the hull and rotatably supported at a predetermined interval in the width direction of the hull;
A port propeller and a starboard propeller fixed respectively to axial ends of the port propeller shaft and the starboard propeller shaft;
A port shaft bracket and a starboard shaft bracket provided on the stern for rotatably supporting the port propeller shaft and the starboard propeller shaft;
A rudder disposed behind the hull from the port propeller and the starboard propeller;
A skeg disposed on the bottom of the ship between the port propeller shaft and the starboard propeller shaft;
With
L1 is a front-to-back distance between the port propeller shaft and the starboard propeller shaft projecting outward from the stern and the center of the port propeller and starboard propeller;
The width at the lowest end position of the skeg at the center position of the port propeller and the center position of the starboard propeller L1 / 2 forward is b1, and the axis of the port propeller shaft and the starboard propeller shaft at the intermediate position. When the width of the skeg at the position is b2,
b1 ≦ b2 is set ,
When the diameters of the port propeller and the starboard propeller are Dp, the shortest distance d between the tip of the port propeller and the tip of the starboard propeller on the center side in the width direction of the hull is 0 <d ≦ 0.2 Dp Set,
Respective rotation directions of the port propeller and the starboard propeller are set inwardly to rotate from the outside of the hull toward the center side in the width direction at the upper part of the port propeller and the starboard propeller.
A marine vessel propulsion device characterized by that.   2. The ship according to claim 1, wherein the skeg is provided with a bulging portion having a width wider than the width b <b> 1 and the width b <b> 2 between the lowest end position and the axial center position at the intermediate position. Propulsion device.   2. The marine vessel propulsion device according to claim 1, wherein the skeg has a tapered shape whose width decreases downward from the ship bottom at the intermediate position.   4. The marine vessel propulsion device according to claim 3, wherein the skeg is provided with inclined surfaces on both sides at which the lowest end position approaches the center side in the width direction of the hull at the intermediate position.   2. The marine vessel propulsion device according to claim 1, wherein the skeg has the same width shape with the same width downward from the ship bottom at the intermediate position. The skeg has a shape in which the rear side of the center in the ship width direction at the bottom of the ship extends in the horizontal direction and is curved upward from the middle toward the rear, and is curved upward from the horizontal plane along the ship bottom toward the rear. 6. The ship according to claim 1, wherein the inflection position to the curved surface is provided in a region from a center of the port propeller and the starboard propeller to the intermediate position. Propulsion device.   The bottom end shape of the skeg and the ship bottom is a concave shape that is recessed toward the center in the width direction of the hull as seen from the ship bottom side. The marine vessel propulsion device described in the paragraph. The said portside propeller shaft and said starboard propeller shaft are set so that the distance between the shaft centers increases toward the rear of the hull, according to any one of claims 1 to 7 . Ship propulsion device. The starboard propeller shaft and the port propeller shaft, one of claims 1 to 8, characterized in that the height from the ship bottom to the axis is set smaller toward the rear of the hull The ship propulsion device according to one item. A distance L2 from the center of the port propeller and the center of the starboard propeller to the leading edge of the rudder at the axial position of the port propeller shaft and the starboard propeller shaft, where Dp is the diameter of the port propeller and the starboard propeller Is set to 0 <L2 ≦ 1.0Dp, The marine vessel propulsion device according to any one of claims 1 to 9 , wherein: The marine vessel propulsion apparatus according to any one of claims 1 to 10, wherein a port rudder and a starboard rudder are respectively arranged behind the hull from the port propeller and the starboard propeller. 2. The portside propeller shaft and the starboard propeller shaft are rotatably supported by a portside intermediate shaft bracket and a starboard intermediate shaft bracket at an intermediate portion protruding from a stern tube to an outer portion of the hull. The marine vessel propulsion device according to claim 11. The port intermediate shaft bracket and the starboard intermediate shaft bracket extend in a V shape upward from the cylindrical support portion and a cylindrical support portion that rotatably supports the port propeller shaft and the starboard propeller shaft. The marine vessel propulsion device according to claim 12, wherein an upper end includes a plurality of struts connected to the stern. The port intermediate shaft bracket and the starboard intermediate shaft bracket extend straightly upward in the vertical direction from the cylindrical support portion that rotatably supports the port propeller shaft and the starboard propeller shaft. The marine vessel propulsion device according to claim 12, characterized in that each upper end is constituted by one strut connected to the stern. The port intermediate shaft bracket and the starboard intermediate shaft bracket each include a cylindrical support portion that rotatably supports the port propeller shaft and the starboard propeller shaft, and a tip that extends straight from the cylindrical support portion in the lateral direction. The marine vessel propulsion device according to claim 12, wherein the marine vessel propulsion device is composed of one strut connected to the skeg. The port intermediate shaft bracket and the starboard intermediate shaft bracket include a cylindrical support portion that rotatably supports the port propeller shaft and the starboard propeller shaft, and a tip that extends straight from the cylindrical support portion in an oblique direction. The marine vessel propulsion device according to claim 12, wherein the marine vessel propulsion device is composed of one strut connected to the skeg. The port intermediate shaft bracket and the starboard intermediate shaft bracket are provided in a region between the intermediate position and the position where the port propeller shaft and the starboard propeller shaft project from the stern tube to the outer portion of the hull. The marine vessel propulsion device according to any one of claims 12 to 16, characterized by: Between the skeg and the port side propeller shaft and the starboard propeller shaft, the water flow rising on both sides of the skeg is open so as to smoothly flow without being interrupted by the skeg. The marine vessel propulsion device according to any one of claims 1 to 17. A marine vessel comprising the marine vessel propulsion device according to any one of claims 1 to 18 .

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