Strut rotation mechanism for hydrofoils

Abstract

To stably rotate a strut without enlarging a strut rotation mechanism.SOLUTION: A strut rotation mechanism 7 of a hydrofoil vessel 1 includes: a front unit strut 3 of a front unit foil 4 (hydrofoil); a shaft 72 coupled to the front unit strut 3 for rotating the front unit strut 3 by rotation; and a top unit bearing 75 and a bottom unit bearing 76 for supporting the shaft 72 so as to freely rotate. At least one of the top unit bearing 75 and the bottom unit bearing 76 is a bearing capable of supporting radial load and axial load.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The technology disclosed in this application relates to a strut rotation mechanism for a hydrofoil vessel. [Background technology]

[0002] For example, as disclosed in Patent Document 1, a hydrofoil vessel is known that includes hydrofoils supported by struts. The strut is provided so as to be rotatable about its axis, and also functions as a rudder. A shaft (commonly known as a king post) is connected to the upper part of the strut, and the shaft is rotatably supported by a bearing. In other words, the strut is rotatably supported by the bearing via the shaft. In such a strut rotation mechanism, the strut rotates when the shaft is rotated by an actuator. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Publication No. 3-15291 Summary of the Invention [Problem to be solved by the invention]

[0004] In a hydrofoil vessel, not only radial loads (i.e. loads in the front-rear and left-right directions of the hydrofoil vessel) but also axial loads (loads in the up-down direction of the hydrofoil vessel) act on the shaft, and unless this axial load is also properly supported, it is difficult to rotate the strut stably. However, Patent Document 1 does not disclose a method for supporting this axial load, and depending on the support method used, the overall size of the strut rotation mechanism described above may increase.

[0005] The technology disclosed in this application has been made in consideration of these points, and its purpose is to provide a strut rotation mechanism that can rotate a strut stably without increasing its size. [Means for solving the problem]

[0006] The technology disclosed in this application is a strut rotation mechanism for a hydrofoil vessel, comprising a strut for a hydrofoil, a shaft connected to the strut and rotating to rotate the strut, and one or more bearings for rotatably supporting the shaft, at least one of which is capable of supporting radial and axial loads. Effect of the Invention

[0007] According to the strut rotation mechanism for a hydrofoil ship disclosed in the present application, the strut can be rotated stably without increasing the size of the strut rotation mechanism. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view of the hydrofoil vessel seen from the front right. [Diagram 2] FIG. 2 is a perspective view of the hydrofoil vessel seen from the rear left. [Diagram 3] FIG. 3 is a perspective view of the front and rear struts and foils of a hydrofoil vessel. [Figure 4] FIG. 4 is a schematic perspective view of the strut rotation mechanism as viewed from the right rear. [Diagram 5] FIG. 5 is a cross-sectional view showing a schematic configuration of a strut rotation mechanism. [Figure 6] FIG. 6 is an enlarged cross-sectional view showing a main part of the strut rotation mechanism. [Figure 7] FIG. 7 is a cross-sectional view showing a schematic configuration of the upper end portion of the shaft. [Figure 8] FIG. 8 is a plan view showing a schematic configuration of the fall prevention member. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an exemplary embodiment will be described in detail with reference to the drawings. Fig. 1 is a perspective view of a hydrofoil vessel 1 as viewed from the right front. Fig. 2 is a perspective view of the hydrofoil vessel 1 as viewed from the left rear. Fig. 3 is a perspective view of front and rear struts and foils of the hydrofoil vessel 1.

[0010] The hydrofoil vessel 1 comprises a hull 2, one front strut 3, a front foil 4 attached to the front strut 3, three rear struts 5, an rear foil 6 attached to the rear strut 5, two jet pumps 11, and two gas turbine engines 12. Note that the numbers of the front struts 3, front foils 4, rear foils 6, etc. are not limited to these.

[0011] Hereinafter, the forward and backward directions are defined as "fore" and "aft" in the direction of travel of the hydrofoil ship 1, respectively. The left-right directions are defined as "right" and "left" in the direction of travel of the hydrofoil ship 1, respectively. The height direction of the hydrofoil ship 1 is defined as the up-down direction.

[0012] The front strut 3 is provided at the front of the hull 2, in the center in the left-right direction. The upper end of the front strut 3 is connected to the bottom of the hull 2. The front strut 3 is provided to the hull 2 ​​so as to rotate in the fore-aft direction (i.e. so as to rotate around an axis extending in the left-right direction). Specifically, the front strut 3 is configured to rotate in the fore-aft direction between a first state in which it extends downward from the bottom of the hull 2, and a second state in which it extends forward from the bottom of the hull 2. Furthermore, the front strut 3 is provided to the hull 2 ​​so as to be rotatable around its axis. Hereinafter, when describing the configuration of the front strut 3 etc., unless otherwise specified, the front strut 3 is assumed to be in the first state. The front strut 3 is an example of a strut.

[0013] The front foils 4 extend to the left and right, respectively, from the lower ends of the front struts 3. In other words, the front foils 4 are an example of hydrofoils, and are supported by the front struts 3.

[0014] A plurality of front flaps 41 are provided at the rear end of the front foil 4. The front flaps 41 are provided rotatably about axes extending in the left-right direction of the hull 2. The lift force generated by the front foil 4 is adjusted by the rotation of the front flaps 41. The front flaps 41 are an example of a flap.

[0015] The three rear struts 5 are arranged side by side in the left-right direction at the rear of the hull 2. The upper ends of the rear struts 5 are connected to the bottom of the hull 2. The rear struts 5 are arranged on the hull 2 ​​so as to rotate in the fore-aft direction (i.e. so as to rotate around an axis extending in the left-right direction). Specifically, the rear struts 5 are configured to rotate in the fore-aft direction between a first state in which they extend downward from the bottom of the hull 2, and a second state in which they extend rearward from the bottom of the hull 2. Hereinafter, when distinguishing between the three rear struts 5, they will be referred to as the left rear strut 5, the central rear strut 5, and the right rear strut 5, from the left.

[0016] The rear foil 6 is provided on the lower ends of the three rear struts 5. Specifically, the rear foil 6 extends left and right so as to connect the lower end of the left rear strut 5 with the lower end of the central rear strut 5, and the rear foil 6 extends left and right so as to connect the lower end of the right rear strut 5 with the lower end of the central rear strut 5. In other words, the rear foil 6 is an example of a hydrofoil, and is supported by the rear struts 5.

[0017] A plurality of rear flaps 61 are provided at the rear end of the rear foil 6. The rear flaps 61 are provided rotatably about axes extending in the left-right direction. The rear flaps 61 rotate to adjust the lift force generated by the rear foil 6. The rear flaps 61 are an example of a flap.

[0018] One jet pump 11 and one gas turbine engine 12 form one pair, and the gas turbine engine 12 drives the jet pump 11. In other words, the hydrofoil ship 1 has two pairs of jet pumps 11 and gas turbine engines 12.

[0019] The two jet pumps 11 are arranged on the left and right sides at the rear and bottom of the hull 2. A water supply port 51 that opens forward is provided at the lower end of the central rear strut 5. The upper end of the central rear strut 5 branches into two, each connected to one of the two jet pumps 11. A water supply passage is formed inside the central rear strut 5. Water flows from the water supply port 51 into the interior of the central rear strut 5, flows through the water supply passage, and flows into each of the two jet pumps 11.

[0020] The two gas turbine engines 12 are disposed on the left and right sides, respectively, at the rear of the hull 2. Each gas turbine engine 12 is connected to a jet pump 11 via a reduction gear (not shown) in a gearbox 12a.

[0021] The jet pump 11 is an axial water jet pump that jets water backward to propel the hydrofoil boat 1 forward.

[0022] The hydrofoil vessel 1 can be switched between a boat-running state (not shown) in which the vessel travels with the bottom of the hull 2 ​​submerged, and a foil-running state (the state shown in Figures 1 and 2) in which the vessel travels with the hull 2 ​​raised above the water surface by the lift of the front foil 4 and the rear foil 6. In the boat-running state, both the front strut 3 and the rear strut 5 are in the first state or the second state. Also, in the boat-running state, one of the front strut 3 and the rear strut 5 may be in the first state and the other in the second state. In the foil-running state, both the front strut 3 and the rear strut 5 are in the first state. In other words, the hydrofoil vessel 1 is a so-called fully submerged hydrofoil vessel in which the entire front foil 4 and the rear foil 6 are submerged below the water surface when foil-running.

[0023] In addition, when the hydrofoil vessel 1 is turning, the front strut 3 rotates about its axis to balance the vessel during turning. In other words, the front strut 3 has a function of supporting the front foil 4 and a function as a rudder.

[0024] <Strut rotation mechanism> Fig. 4 is a schematic perspective view of the strut rotation mechanism 7 as viewed from the rear right. Fig. 5 is a cross-sectional view showing a schematic configuration of the strut rotation mechanism 7.

[0025] The hydrofoil vessel 1 is equipped with a strut rotation mechanism 7 that rotates the front strut 3. The strut rotation mechanism 7 includes the front strut 3, an actuator 71, a shaft 72 (also commonly known as a king post), a torque arm 73, a housing 74, and multiple bearings (two in this example). Unless otherwise specified, the positions and directions mentioned here refer to the positions and directions in the hydrofoil vessel 1 in a foiling state.

[0026] The front strut 3 extends in the vertical direction. The shaft 72 is connected to the front strut 3 and rotates to rotate the front strut 3.

[0027] Specifically, the shaft 72 is a cylindrical member extending in the vertical direction. The shaft 72 is connected to the upper end of the front strut 3. More specifically, the shaft 72 is connected to the front strut 3 so as to be unable to rotate relative to the front strut 3. The shaft 72 is inserted into an opening 31 formed in the upper end of the front strut 3. A cylindrical retaining portion 32 is formed inside the front strut 3. A lower end 725 of the shaft 72 inserted into the front strut 3 is fitted inside the retaining portion 32. The lower end 725 of the shaft 72 is connected to the retaining portion 32 by a pin 33. In this way, the shaft 72 is fixed to the front strut 3, and therefore the shaft 72 and the front strut 3 rotate together.

[0028] The two bearings rotatably support the shaft 72. In this example, the two bearings are an upper bearing 75 and a lower bearing 76. The upper bearing 75 and the lower bearing 76 are arranged side by side and spaced apart in the axial direction. The upper bearing 75 and the lower bearing 76 support a portion of the shaft 72 that is located outward of the front strut 3.

[0029] The upper bearing 75 and the lower bearing 76 are held by a housing 74. Specifically, the housing 74 is formed with an upper holding portion 742 that holds the upper bearing 75 and a lower holding portion 743 that holds the lower bearing 76. The housing 74 is fixed to the hull 2. In other words, the upper bearing 75 and the lower bearing 76 are held by the hull 2 ​​via the housing 74.

[0030] A torque arm 73 is connected to a portion of the shaft 72 above the upper bearing 75. More specifically, the torque arm 73 is connected to the shaft 72 so as to be non-rotatable relative to the shaft 72. In this example, a spline (not shown) is formed on the outer circumferential surface of the shaft 72, and the torque arm 73 is fitted into the spline. In this way, the strut rotation mechanism 7 is configured so that the shaft 72, the torque arm 73, and the front strut 3 rotate integrally.

[0031] A nut 78 is screwed onto the upper end of the shaft 72 to prevent the shaft 72 from slipping out of the upper bearing 75 and the lower bearing 76 (i.e., to prevent the front strut 3 from falling off). In other words, a male thread (not shown) that screws into the nut 78 is formed on the outer circumferential surface of the upper end of the shaft 72.

[0032] Spacers 77a and 77b for maintaining the distance between the members are provided on the outer periphery of the shaft 72. Specifically, a spacer 77a is provided for maintaining the distance between the torque arm 73 and the upper bearing 75, and a spacer 77b is provided for maintaining the distance between the lower bearing 76 and the front strut 3.

[0033] The actuator 71 rotates the shaft 72. More specifically, the actuator 71 is connected to a torque arm 73, and rotates the shaft 72 by rotating the torque arm 73. In this example, the actuator 71 is a hydraulic cylinder. That is, a piston rod of the hydraulic cylinder is connected to the torque arm 73, and a cap side of the hydraulic cylinder is connected to a bracket 741 provided on a housing 74. The torque arm 73 rotates as the piston rod advances and retreats.

[0034] The shaft 72 has two tapered portions (upper tapered portion 722 and lower tapered portion 724). The tapered portions are portions of the shaft 72 whose outer circumferential surface is a tapered surface. Specifically, the upper tapered portion 722 and the lower tapered portion 724 are arranged in order from top to bottom in the vertical direction (the axial direction of the shaft 72). The upper tapered portion 722 has an outer diameter that increases downward, and is located within the housing 74. The lower tapered portion 724 has an outer diameter that decreases downward, and is the portion that is inserted into the front strut 3.

[0035] In the shaft 72, the portion above the upper tapered portion 722 is a cylindrical portion 721, and the portion between the upper tapered portion 722 and the lower tapered portion 724 is a cylindrical portion 723. The cylindrical portions 721, 723 are portions of the shaft 72 whose outer circumferential surfaces are cylindrical. In this example, the outer diameter of the cylindrical portion 723 is larger than the outer diameter of the cylindrical portion 721. The upper bearing 75 and the torque arm 73 are located in the cylindrical portion 721, and the lower bearing 76 and the spacer 77b are located in the cylindrical portion 723. The lower tapered portion 724 is the portion that is inserted into the front strut 3.

[0036] Providing the shaft 72 with the upper tapered portion 722 in this manner makes it easier to mount the lower bearing 76 on the shaft 72. Providing the shaft 72 with the lower tapered portion 724 makes it easier to insert the shaft 72 into the front strut 3.

[0037] FIG. 6 is an enlarged cross-sectional view showing a main part of the strut rotation mechanism 7. As shown in FIG.

[0038] Both the upper bearing 75 and the lower bearing 76 are bearings capable of supporting radial and axial loads. A radial load is a load acting on the shaft 72 in the front-rear and left-right directions (i.e., in a direction perpendicular to the axial direction of the shaft 72). An axial load is a load acting on the shaft 72 in the up-down direction (i.e., in the axial direction of the shaft 72, as indicated by the arrow in FIG. 6).

[0039] Both the upper bearing 75 and the lower bearing 76 are spherical plain bearings. In other words, a spherical plain bearing is an example of a bearing capable of supporting radial and axial loads. Both the upper bearing 75 and the lower bearing 76 are spherical plain bearings configured to support an axial load in substantially only one direction, rather than supporting an axial load in both directions.

[0040] Specifically, the upper bearing 75 is configured to support an axial load that is substantially downward in the up-down direction. The lower bearing 76 is configured to support an axial load that is substantially upward in the up-down direction. In other words, the upper bearing 75 and the lower bearing 76 are arranged so that the directions of the axial loads that they can support are opposite to each other. Therefore, in the strut rotation mechanism 7, both upward and downward axial loads acting on the shaft 72 are supported by the upper bearing 75 and the lower bearing 76.

[0041] More specifically, the upper bearing 75 and the lower bearing 76 are spherical plain bearings having outer rings 751, 761 and inner rings 752, 762, respectively. In the upper bearing 75, the sliding contact surfaces of the outer ring 751 and the inner ring 752 (hereinafter also referred to as sliding surfaces 751a, 752a) are spherical. In the lower bearing 76, the sliding contact surfaces of the outer ring 761 and the inner ring 762 (hereinafter also referred to as sliding surfaces 761a, 762a) are spherical. That is, in the upper bearing 75, the sliding surface 751a of the outer ring 751 slides against the sliding surface 752a of the inner ring 752. In the lower bearing 76, the sliding surface 761a of the outer ring 761 slides against the sliding surface 762a of the inner ring 762.

[0042] The upper bearing 75 and the lower bearing 76 have different outer diameters at both end faces of the inner rings 752, 762 in the axial direction of the shaft 72 so as to support an axial load in only one direction. Specifically, in the upper bearing 75, the outer diameter of the lower end face 752c of the inner ring 752 is smaller than the outer diameter of the upper end face 752b so as to support an axial load substantially only in the downward direction. In the lower bearing 76, the outer diameter of the upper end face 762c of the inner ring 762 is smaller than the outer diameter of the lower end face 762b so as to support an axial load substantially only in the upward direction.

[0043] In other words, the upper bearing 75 and the lower bearing 76 have different inner diameters at both end faces of the outer rings 751, 761 in the axial direction of the shaft 72 so as to support an axial load in only one direction. Specifically, in the upper bearing 75, the inner diameter of the lower end face 751c of the outer ring 751 is formed smaller than the inner diameter of the upper end face 751b so as to support an axial load substantially only in the downward direction. In the lower bearing 76, the inner diameter of the upper end face 761b of the outer ring 761 is formed smaller than the inner diameter of the lower end face 761c so as to support an axial load substantially only in the upward direction.

[0044] By forming the inner rings 752, 762 and the outer rings 751, 761 in this manner, it becomes easier to insert the inner rings 752, 762 into the outer rings 751, 761. That is, in the upper bearing 75, it becomes easier to insert the inner ring 752 from above into the outer ring 751. In the lower bearing 76, it becomes easier to insert the inner ring 762 into the outer ring 761 from below.

[0045] Sleeves 726, 727 that fit with the upper bearing 75 and the lower bearing 76 are fitted onto the outer periphery of the shaft 72 in the portions that correspond to the upper bearing 75 and the lower bearing 76.

[0046] Specifically, the sleeves 726, 727 are cylindrical members made of, for example, metal. A sleeve 726 is fitted onto the outer periphery of a portion of the columnar portion 721 of the shaft 72 that corresponds to the upper bearing 75. The sleeve 726 is fitted into an inner ring 752 of the upper bearing 75. A sleeve 727 is fitted onto the outer periphery of a portion of the columnar portion 723 of the shaft 72 that corresponds to the lower bearing 76. The sleeve 727 is fitted into an inner ring 762 of the lower bearing 76.

[0047] By providing the sleeves 726, 727 on the shaft 72 in this way, the outer circumferential surface of the shaft 72 is protected by the sleeves 726, 727. In other words, it is possible to prevent wear of the shaft 72 caused by the shaft 72 sliding against the inner rings 752, 762 of the upper bearing 75 and the lower bearing 76. As a result, it is only necessary to replace the sleeves 726, 727 instead of the shaft 72, which improves the ease of maintenance of the strut rotation mechanism 7 and reduces maintenance costs.

[0048] Additionally, the upper bearing 75 and the lower bearing 76 are lubricant-supplied spherical plain bearings. The strut rotation mechanism 7 has a lubricating device 8. The lubricating device 8 supplies a lubricant such as lubricating oil to the upper bearing 75 and the lower bearing 76.

[0049] The lubrication device 8 has a pump 81, a tank 82, and a control unit 85. The suction side of the pump 81 is connected to the tank 82 via a first pipe 83. The discharge side of the pump 81 is connected to the upper bearing 75 (outer ring 751) and the lower bearing 76 (outer ring 761) via a second pipe 84. The tank 82 stores a lubricant. In the lubrication device 8, the pump 81 is driven to supply the lubricant from the tank 82 to the upper bearing 75 and the lower bearing 76. This lubricates the sliding parts of the upper bearing 75 and the lower bearing 76, thereby reducing the sliding resistance.

[0050] Furthermore, when the torque of the shaft 72 caused by the actuator 71 increases to a predetermined value, the upper bearing 75 and the lower bearing 76 are supplied with lubricant. Specifically, when the torque of the shaft 72 caused by the actuator 71 increases to a predetermined value, the control unit 85 drives the pump 81. In this example, when the differential pressure between the supply pressure and discharge pressure of the hydraulic oil in the actuator 71, which is a hydraulic cylinder, increases to a predetermined threshold value, the control unit 85 drives the pump 81, assuming that the torque of the shaft 82 caused by the actuator 71 has increased to a predetermined value.

[0051] That is, in the strut rotation mechanism 7, when the rotational force of the shaft 72 by the actuator 71 increases to a predetermined value, it is assumed that the sliding resistance between the shaft 72 and the upper bearing 75 and lower bearing 76 has increased, and lubricant is supplied to the upper bearing 75 etc. In this way, seizure and other problems of the upper bearing 75 etc. can be prevented in advance.

[0052] Fig. 7 is a cross-sectional view showing a schematic configuration of the upper end portion of shaft 72. Fig. 8 is a plan view showing a schematic configuration of fall prevention member 79. Note that fall prevention member 79 and a cover plate 728, which will be described later, are omitted from Fig. 5.

[0053] The strut rotation mechanism 7 has a fall prevention member 79 that prevents the shaft 72 and the front strut 3 from falling (dislodging) from the housing 74. The fall prevention member 79 is fixed to both the shaft 72 and the nut 78.

[0054] Specifically, fall prevention member 79 is a plate member having a substantially circular ring shape. More specifically, fall prevention member 79 is a C-shaped plate member obtained by cutting away a portion of the circular ring shape (see FIG. 8). The outer diameter of fall prevention member 79 is larger than the outer diameter of the upper end of shaft 72 and smaller than the outer diameter of nut 78. Fall prevention member 79 is attached to straddle the upper end surface of shaft 72 and the upper end surface of nut 78. A cover plate 728 is provided on the upper end surface of shaft 72 so as to cover the upper end opening of shaft 72.

[0055] Fall prevention member 79 and the upper end surface of shaft 72 are fastened by bolt 79a. Fall prevention member 79 and the upper end surface of nut 78 are fastened by bolt 79b. Fall prevention member 79 is formed with a plurality of through holes 791 through which bolts 79a pass, and a plurality of through holes 792 through which bolts 79b pass are formed on the outer periphery of through hole 791. Meanwhile, a threaded hole 729 into which bolt 79a screws is formed in the upper end surface of shaft 72, and a threaded hole 781 into which bolt 79b screws is formed in the upper end surface of nut 78.

[0056] In this way, by connecting the shaft 72 and the nut 78 via a fall prevention member 79, it is possible to prevent the shaft 72 and the front strut 3 from falling off even if wear occurs, for example, in the male thread of the shaft 72 that screws into the nut 78 during operation or maintenance.

[0057] As described above, the strut rotation mechanism 7 of the hydrofoil ship 1 of the embodiment includes the front strut 3 (strut) of the front foil 4 (hydrofoil), the shaft 72 that is connected to the front strut 3 and rotates to rotate the front strut 3, and the upper bearing 75 and lower bearing 76 that rotatably support the shaft 72. Both the upper bearing 75 and the lower bearing 76 are bearings capable of supporting radial loads and axial loads. Specifically, the upper bearing 75 is configured to be able to support downward axial loads, and the lower bearing 76 is configured to be able to support upward axial loads.

[0058] With the above-described configuration, not only radial loads but also axial loads in both directions can be supported by the upper bearing 75 and the lower bearing 76. Therefore, compared to, for example, a case in which a mechanism for supporting the axial load is provided separately from conventional bearings, the axial load can be supported without increasing the size of the strut rotation mechanism 7. Therefore, the front strut 3 can be rotated stably without increasing the size of the strut rotation mechanism 7.

[0059] In addition, since the upper bearing 75 and the lower bearing 76 are spherical plain bearings, they can support larger radial and axial loads than, for example, when rolling bearings are used, and therefore the front strut 3 can rotate more stably.

[0060] Furthermore, the outer diameters of both end faces of the inner rings 752, 762 in the axial direction of the shaft 72 are different from each other so that the upper bearing 75 and the lower bearing 76 support an axial load in only one direction. The upper bearing 75 and the lower bearing 76 are arranged so that the directions of the axial loads they support are opposite to each other. That is, in the upper bearing 75, the outer diameter of the lower end face 752c of the inner ring 752 is formed smaller than the outer diameter of the upper end face 752b so that the upper bearing 75 supports an axial load substantially only in the downward direction. In the lower bearing 76, the outer diameter of the upper end face 762c of the inner ring 762 is formed smaller than the outer diameter of the lower end face 762b so that the lower bearing 76 supports an axial load substantially only in the upward direction.

[0061] The above-described configuration makes it easy to insert the inner rings 752, 762 into the outer rings 751, 761 in the upper bearing 75 and the lower bearing 76. This makes it possible to construct a strut rotation mechanism 7 that is easy to assemble while being capable of supporting axial loads in both directions.

[0062] Moreover, the upper bearing 75 and the lower bearing 76, that is, the bearings capable of supporting radial and axial loads, are lubricant-supplied bearings.

[0063] According to the above configuration, since the upper bearing 75 and the lower bearing 76 are required to have high lubrication performance because they can support not only radial loads but also axial loads, the bearings are lubricant-supplied, so high lubrication performance can be ensured by appropriately supplying lubricant. Therefore, problems such as seizure of the upper bearing 75 and the lower bearing 76 can be prevented in advance.

[0064] The strut rotation mechanism 7 further includes an actuator 71 that rotates the shaft 72. Lubricant is supplied to the upper bearing 75 and the lower bearing 76, i.e., the bearings capable of supporting radial and axial loads, when the rotation force of the shaft 72 by the actuator 71 increases to a predetermined value.

[0065] When the torque of shaft 72 caused by actuator 71 rises to a predetermined value, there is a possibility that the sliding resistance between shaft 72 and upper bearing 75 and lower bearing 76 may be abnormally high. According to the above-described configuration, when the torque of shaft 72 caused by actuator 71 rises to a predetermined value, lubricant is supplied to upper bearing 75 etc., so that defects such as seizure of upper bearing 75 and lower bearing 76 can be effectively prevented.

[0066] Additionally, sleeves 726, 727 that fit with the upper bearing 75 and the lower bearing 76 are fitted onto the outer periphery of the shaft 72 at the portions corresponding to the upper bearing 75 and the lower bearing 76.

[0067] According to the above-described configuration, the sleeves 726, 727 can prevent wear of the shaft 72 caused by the shaft 72 sliding against the inner rings 752, 762 of the upper bearing 75 and the lower bearing 76. Because of this, it is only necessary to replace the sleeves 726, 727 instead of the shaft 72, which improves the ease of maintenance of the strut rotation mechanism 7 and reduces maintenance costs.

[0068] (Other embodiments) As described above, the above embodiment has been described as an example of the technology disclosed in this application. However, the technology in this disclosure is not limited to this, and can be applied to embodiments in which modifications, replacements, additions, omissions, etc. are appropriately performed. In addition, it is also possible to combine the components described in the above embodiment to form a new embodiment. In addition, among the components described in the attached drawings and detailed description, not only components essential for solving the problem but also components that are not essential for solving the problem in order to exemplify the technology may be included. Therefore, the fact that these non-essential components are described in the attached drawings and detailed description should not immediately be taken to mean that these non-essential components are essential.

[0069] For example, in the strut rotation mechanism 7 of the embodiment, two bearings are used, but the present invention is not limited to this and one bearing may be used. In this case, the bearing is a bearing capable of supporting radial loads and axial loads. In this case, the bearing may be capable of supporting axial loads in one direction, or may be capable of supporting axial loads in both directions.

[0070] Also, there may be three or more bearings. In this case, at least one bearing is capable of supporting radial loads and axial loads. In this case, the bearing may be capable of supporting axial loads in one direction, or may be capable of supporting axial loads in both directions.

[0071] In addition, in the strut rotation mechanism 7 of the above embodiment, a spherical plain bearing is used as a bearing capable of supporting radial and axial loads, but the present invention is not limited to this, and for example, a tapered roller bearing may be used. As the tapered roller bearing, either a so-called single-row type capable of supporting an axial load in one direction or a so-called double-row type capable of supporting axial loads in both directions may be used.

[0072] Furthermore, in the strut rotation mechanism 7 of the above embodiment, the upper bearing 75 and the lower bearing 76 may be spherical plain bearings capable of supporting axial loads in both directions, rather than in one direction.

[0073] In addition, in the strut rotation mechanism 7 of the above embodiment, the upper bearing 75 and the lower bearing 76 may be arranged upside down. In other words, the upper bearing may be arranged to support an upward axial load, and the lower bearing may be arranged to support a downward axial load. [Explanation of symbols]

[0074] 1 hydrofoil 3 Front strut (strut) 4 Front foil (hydrofoil) 7 Strut rotation mechanism 71 Actuator 72 Shaft 75 Upper bearing (bearing) 76 Lower bearing (bearing) 751,761 Outer ring 752,762 Inner circle 752b,762c Upper end face (end face) 752c,762b Lower end face (end face) 726,727 Sleeve

Claims

1. A strut of the hydrofoil; a shaft coupled to the strut and rotatable to rotate the strut; an upper bearing and a lower bearing that rotatably support the shaft; Each of the upper bearing and the lower bearing is a bearing capable of supporting a radial load and an axial load, The upper bearing supports an axial load in only one direction of the axial direction of the shaft, and supports the shaft so as not to be displaceable in the one direction, The lower bearing supports an axial load only in the opposite direction of the axial direction of the shaft to the upper bearing, and supports the shaft so as not to be displaceable in the opposite direction, A strut rotation mechanism for a hydrofoil vessel, wherein the shaft is supported by both the upper bearing and the lower bearing so as not to be displaceable in the axial direction of the shaft.

2. 2. The strut rotation mechanism for a hydrofoil vessel according to claim 1, A strut rotation mechanism for a hydrofoil vessel, wherein each of the upper bearing and the lower bearing is a lubricated bearing.

3. 3. The strut rotation mechanism for a hydrofoil vessel according to claim 2, further comprising an actuator for rotating the shaft; A strut rotation mechanism for a hydrofoil vessel, wherein lubricant is supplied to each of the upper bearing and the lower bearing when the rotational force of the shaft by the actuator increases to a predetermined value.

4. 2. The strut rotation mechanism for a hydrofoil vessel according to claim 1, Each of the upper bearing and the lower bearing is a spherical plain bearing having an outer ring and an inner ring, The upper bearing and the lower bearing each have different outer diameters at both end faces of the inner ring in the axial direction of the shaft so as to support an axial load in only one direction, A strut rotation mechanism for a hydrofoil vessel, wherein the upper bearing and the lower bearing are arranged so that the directions of the axial loads they support are opposite to each other.

5. A strut for a hydrofoil; a shaft coupled to the strut and rotatable to rotate the strut; an upper bearing and a lower bearing that rotatably support the shaft; Each of the upper bearing and the lower bearing is a bearing capable of supporting a radial load and an axial load, the shaft is supported by both the upper bearing and the lower bearing so as to be immovable in the axial direction of the shaft, Each of the upper bearing and the lower bearing is a spherical plain bearing having an outer ring and an inner ring, The upper bearing and the lower bearing each have different outer diameters at both end faces of the inner ring in the axial direction of the shaft so as to support an axial load in only one direction, The upper bearing and the lower bearing are arranged so that the directions of the axial loads they support are opposite to each other, In the upper bearing, the outer diameter of the lower end face of the inner ring is smaller than the outer diameter of the upper end face so as to support a downward axial load, A strut rotation mechanism for a hydrofoil vessel, wherein the outer diameter of the upper end face of the inner ring of the lower bearing is smaller than the outer diameter of the lower end face thereof so as to support an upward axial load.

6. 2. The strut rotation mechanism for a hydrofoil vessel according to claim 1, A strut rotation mechanism for a hydrofoil vessel, wherein a sleeve that fits into the upper bearing and the lower bearing is fitted onto the outer periphery of the portion of the shaft that corresponds to the upper bearing and the lower bearing.

7. 2. The strut rotation mechanism for a hydrofoil vessel according to claim 1, A strut rotation mechanism for a hydrofoil vessel, wherein each of the upper bearing and the lower bearing is a spherical plain bearing.

8. A strut of the hydrofoil; a shaft coupled to the strut and rotatable to rotate the strut; an upper bearing and a lower bearing that rotatably support the shaft; Each of the upper bearing and the lower bearing is a bearing capable of supporting a radial load and an axial load, the shaft has an upper tapered portion, a lower tapered portion disposed below the upper tapered portion and inserted into the strut, and a cylindrical portion disposed between the upper tapered portion and the lower tapered portion, The upper tapered portion has an outer diameter that increases downward, The outer diameter of the lower tapered portion becomes smaller as it goes downward, The cylindrical portion has an outer circumferential surface that is a cylindrical surface, A strut rotation mechanism for a hydrofoil vessel, wherein the lower bearing is disposed on the cylindrical portion.

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