Periodic blowout air lubrication system and rotary valve for periodic blowout air lubrication system

Abstract

A periodic blowout air lubrication system comprises a plurality of air blowout ports 10 that are provided to the bottom of a ship, an air supply means 20 that supplies air to the plurality of air blowout ports 10 via a piping route 50, a rotary-type route switching means 30 that is provided midway through the piping route 50, and a control means 40 that controls the rotary-type route switching means 30, wherein: there are a plurality of branch pipes 52, which serve as the piping route 50 and lead to the plurality of air blowout ports 10 at the downstream side of the rotary-type route switching means 30; the air blowout ports 10 to which air is supplied by way of rotation of a valve body of the rotary-type route switching means 30 are switched in a prescribed order, and air can be periodically blown out from all of the plurality of air blowout ports 10 by the rotation of the valve body of the rotary-type route switching means 30. The periodic blowout air lubrication system can be installed in a limited in-ship space, periodically blows air out of the bottom of the ship such that a friction resistance reduction effect by air lubrication is exhibited, and also has excellent durability and maintainability.

Description

Periodic air lubrication system and rotary valve for periodic air lubrication system

[0001] The present invention relates to a blow-off air lubrication system that blows air onto the bottom of a ship to reduce frictional resistance of the hull, and to a rotary valve used in the periodic blow-off air lubrication system.

[0002] Air lubrication systems, which reduce hull frictional resistance by blowing air onto the ship's bottom, are known as hull frictional resistance reduction devices. Techniques for improving the frictional resistance reduction rate of air lubrication systems include continuous blowing and periodic blowing. Patent Document 1 (Patent Document 1) discloses a fluid monitoring device that is attached to the bottom of a ship and monitors the fluid around the bottom. The fluid monitoring device includes a sensor unit including multiple piezoelectric ultrasonic probes whose ultrasonic transmitting and receiving surfaces are fixed so as to be oblique to a surface along the bottom, and a signal processor that processes signals detected by the ultrasonic probes. Claim 4 of the patent document describes a hull frictional resistance reduction system that includes the fluid monitoring device and a bubble jetting mechanism that jets bubbles toward the bottom, the signal processor controlling the bubble jetting timing of the bubble jetting mechanism based on a probability distribution and a flow velocity distribution. Claim 5 of the patent document further describes that the signal processor of the hull frictional resistance reduction system controls the bubble jetting timing of the bubble jetting mechanism so that the bubble jetting timing is at a predetermined cycle for a predetermined duration. Patent Document 2 also discloses an unmanned groundwater pumping and distribution opening and closing device in which a water inlet is provided on one side of an inflow chamber, a fixed plate is provided on the other side, and multiple water passage holes are formed in a ring shape, a rotary opening and closing plate that is fitted with a spring and can rotate in contact with the fixed plate is attached to a rotating shaft, multiple opening and closing holes that can match the water passage holes are arranged in a ring shape on the rotary opening and closing plate, and the opening and closing holes can be opened and closed individually or in any combination using opening and closing valves, a worm wheel is formed on the outer periphery, and can rotate at a reduced speed or stopped for a certain period of time by a motor connected to the extension shaft of the worm, a position sensor that detects the rotation angle is installed on the outer part of the rotating shaft, and the pumping pump and motor are operated by the component circuit of the control circuit to control the water supply from each delivery pipe. Furthermore, Patent Document 3 discloses that in a rotary valve that switches flow paths by selectively connecting or blocking multiple outflow paths through the relative movement of a casing and a valve body, a through hole is provided near the outflow path in the casing, and the valve body is provided with a first communication passage that connects part of the outflow path to form a flow path, and a second communication passage that connects the through hole to another outflow path that is blocked when part of the outflow path is connected by the first communication passage, thereby discharging the fluid in the outflow path from the through hole.Furthermore, Patent Document 4 discloses a flow path switching valve comprising: a drive unit having a motor; a base to which the drive unit is fixed and on which a plurality of flow path pipes are arranged on the same circumference centered on the drive shaft of the drive unit; a disk having at least one window hole on the circumference corresponding to the flow path pipes of the base; power transmission means that is detachably engaged with the drive shaft and transmits rotation from the drive shaft to the disk and presses the disk against the flow path pipes arranged on the base; and a lid that is attached to the base so as to be able to open and close freely and has a cavity that hermetically houses the disk and the power transmission means and at least one flow path pipe that communicates with the cavity.

[0003] Japanese Patent Application Publication No. 2011-163774 Japanese Patent Application Publication No. 9-280393 Japanese Patent Application Publication No. 2004-232698 Microfilm of Japanese Utility Model Application Publication No. 55-8403 (Japanese Utility Model Application Publication No. 56-111367)

[0004] In actual ships, limited onboard space makes it difficult to install multiple blow-out devices when applying an air lubrication system. Patent Document 1 describes controlling the timing of bubble ejection to a predetermined cycle and duration, but uses an electromagnetic valve to open and close the bubble introduction path from the bubble-generating blower to the bubble outlet, raising concerns about electronic control problems and durability. Patent Document 2 relates to an on-off valve for pumping water, but is not used in an air lubrication system that reduces the frictional resistance of the hull. Furthermore, the rotating on-off plate must have the same number of on-off holes as the multiple water passage holes formed in the fixed plate, and multiple on-off valves connected to the on-off holes must also be provided, resulting in a complex configuration. Patent Documents 3 and 4 also relate to rotary valves, but are not used in air lubrication systems that reduce the frictional resistance of the hull. Furthermore, while these systems open and close fluid outlets provided on a fixed plate or lid by rotating a valve seat or disc to allow or block fluid flow, they differ from the technical concept of periodically supplying air. Therefore, the present invention aims to provide a periodic air lubrication system and a rotary valve for a periodic air lubrication system that can be installed in limited space on board a ship, periodically blows air onto the bottom of the ship to reduce frictional resistance through air lubrication, and is also highly durable and easy to maintain.

[0005] According to the present invention, the air lubrication system periodically blows air onto the bottom of a ship to reduce the frictional resistance of the hull, and includes a plurality of air outlets provided on the bottom of the ship, an air supply means for supplying air to the plurality of air outlets via piping paths, a rotary path switching means provided midway through the piping paths, and a control means for controlling the rotary path switching means, and further includes a plurality of branch pipes downstream of the rotary path switching means as piping paths leading to the plurality of air outlets, and the air outlets to which air is supplied are switched in a predetermined order by rotation of a valve element of the rotary path switching means, and the rotation of the valve element of the rotary path switching means makes it possible to periodically blow air from all of the plurality of air outlets. According to the present invention, the air supplied from the air supply means can be distributed by the rotary path switching means to each air outlet via the branch piping and then blown out from the bottom of the ship, thereby reducing the required installation space compared to when a plurality of air supply means and switching means are installed. Furthermore, since the control means controls the rotation of the valve body of the rotary path switching means to periodically and intermittently blow air out of all air outlets onto the bottom of the ship, the number of components and electronic control devices can be reduced compared to a configuration that uses multiple solenoid valves that open and close frequently, thereby improving durability and maintainability.

[0006] The present invention as set forth in claim 2 is characterized in that the rotary path switching means is configured to communicate with either of the branch pipes regardless of the rotation angle of the valve element. According to the present invention as set forth in claim 2, the rotary path switching means is always in communication with the branch pipes that serve as pressure relief routes, thereby preventing excessive increases in internal pressure of the rotary path switching means and reducing increases in rotational torque and air leakage. Furthermore, since the pipe path is not closed during cyclic air blowout, the operation of the air supply means is stable.

[0007] According to a third aspect of the present invention, the rotary path switching means is configured to be able to adjust a duty ratio, which is the ratio of the time between air being blown out from the air outlet and the time when air is not being blown out, and the control means performs control to change the duty ratio by rotating the valve body in accordance with the setting of the air blowing mode. According to the third aspect of the present invention, by the control means performing control to change the duty ratio set by the rotary path switching means in accordance with the mode, it is possible to change the blowing interval in accordance with the navigation conditions of the ship, and to effectively reduce frictional resistance by air lubrication.

[0008] The present invention as set forth in claim 4 is characterized in that the control means performs control to change the rotation speed of the valve element of the rotary path switching means in accordance with the setting of the air blowing mode. According to the present invention as set forth in claim 4, the blowing cycle can be changed by changing the rotation speed, and air can be blown out at a cycle corresponding to each mode.

[0009] According to a fifth aspect of the present invention, the rotary path switching means has a configuration that allows communication between all of the plurality of branch pipes, and the control means adjusts the rotation angle of the valve element of the rotary path switching means in accordance with the setting of the air blowing mode to control continuous blowing of air from all of the air outlets. According to the fifth aspect of the present invention, periodic blowing and continuous blowing can be switched between by selecting the mode with a single rotary path switching means.

[0010] The present invention as set forth in claim 6 is characterized in that the rotary path switching means has a configuration capable of closing all of the plurality of branch pipes, and the control means performs control to adjust the rotation angle of the valve body of the rotary path switching means to close all of the branch pipes when the operation of the air supply means is stopped. According to the present invention as set forth in claim 6, when blowing is not performed, the branch pipes can be shut off by controlling the rotation angle of the valve body of the rotary path switching means to prevent, for example, water from flowing back from the air outlet to all of the branch pipes.

[0011] The present invention as set forth in claim 7 is characterized in that the rotary path switching means is configured to be able to select a predetermined branch pipe from among a plurality of branch pipes, and the control means controls the periodic supply of air from a predetermined air outlet by rotating or rotating forward or reverse the valve element according to the mode setting of the air blowing mode. According to the present invention as set forth in claim 7, for example, in a mode in which periodic blowing is performed using air outlets located toward the center of the hull when the hull is experiencing such large rolling motion that air outlets located toward the sides are exposed from the water, or in a mode in which periodic blowing is performed using all air outlets by alternately switching between air outlets located on the left and right sides of the center of the hull when moderate rolling motion is occurring, the valve element can be rotated or rotated forward or reverse so that air is distributed to the selected predetermined branch pipe, thereby performing periodic blowing according to each mode.

[0012] The present invention as set forth in claim 8 is characterized in that the rotary path switching means is configured to be able to select a predetermined branch pipe from among a plurality of branch pipes, and the control means controls the supply of air from a predetermined air outlet by stopping the rotation of the valve element in accordance with the setting of the air blowing mode. According to the present invention as set forth in claim 8, for example, when the hull is rolling to the extent that the air outlets located closer to the side are exposed from the water, in a mode in which continuous blowing is performed using the air outlets located closer to the center of the hull, continuous blowing according to the mode can be performed by fixing the rotation angle of the valve element so that air is distributed only to the selected predetermined branch pipe.

[0013] The present invention as set forth in claim 9 is characterized in that a temperature rise in the rotary path switching means caused by the supply of heated air from the air supply means is prevented by employing at least one of a cooling means and a temperature rise prevention structure. According to the present invention as set forth in claim 9, it is possible to prevent a decrease in performance, such as an increase in leakage from the rotary path switching means, due to a temperature rise.

[0014] According to the present invention, a rotary valve for a periodic air lubrication system according to claim 10 is a rotary valve used as a rotary path switching means in a periodic air lubrication system, comprising: an outer shell having an air inlet and multiple outlets; a rotating disk as a valve element having a single rotating disk aperture housed in the outer shell; a fixed disk as a valve seat having multiple fixed disk apertures along which the rotating disk slides to guide air to the multiple outlets; biasing means for pressing the rotating disk against the fixed disk; and drive means for rotating the rotating disk via a shaft. According to the present invention described in claim 10, by rotating the rotating disk, the rotating disk apertures overlap with the fixed disk apertures in a predetermined order, and air passes through the fixed disk apertures that overlap with the rotating disk apertures, flows into the branch pipe, and is blown out from the air outlet, thereby enabling periodic supply of air from multiple outlets with a simple configuration.

[0015] According to an eleventh aspect of the present invention, the single rotary disk aperture is configured to overlap at least one of the fixed disk apertures regardless of the rotation angle. According to the eleventh aspect of the present invention, the rotary valve is always in communication with the branch pipe, which serves as a pressure relief route, by always overlapping one of the rotary disk apertures with one of the fixed disk apertures. This prevents the internal pressure of the rotary valve from increasing excessively, thereby reducing increases in rotational torque and air leakage.

[0016] According to a twelfth aspect of the present invention, the rotary valve is configured so that the rotary disk can be replaced with another rotary disk serving as a valve element having a different rotary disk orifice of a different shape from the rotary disk orifice, thereby making the duty ratio variable. According to the twelfth aspect of the present invention, the duty ratio can be changed by replacing the rotary disk with another rotary disk having a different shape of the rotary disk orifice.

[0017] According to a thirteenth aspect of the present invention, the motor further includes an adjustment disk for adjusting the duty ratio, and the overlapping apertures formed by the overlapping of the rotating disk apertures and the adjustment disk apertures of the adjustment disk, or the overlapping apertures of the adjustment disk apertures and the fixed disk apertures, are changeable, thereby making the duty ratio variable. According to the thirteenth aspect of the present invention, the size of the overlapping apertures formed by the overlapping of the rotating disk apertures and the adjustment disk apertures, or the adjustment disk apertures and the fixed disk apertures, can be changed by changing the position of the adjustment disk, thereby changing the duty ratio.

[0018] According to a fourteenth aspect of the present invention, the drive speed of the drive means for rotating the rotary disk can be changed. According to the fourteenth aspect of the present invention, the rotation speed of the rotary disk can be changed to change the blowing cycle.

[0019] According to a fifteenth aspect of the present invention, the rotary disk apertures are configured to have a rotation angle that covers all of the plurality of fixed disk apertures as the rotary disk rotates, and by adjusting the rotation angle of the rotary disk, the plurality of fixed disk apertures that guide air to the plurality of outlets are communicated, thereby enabling continuous air blowing. According to the fifteenth aspect of the present invention, it is possible to switch between cyclic blowing and continuous blowing with a single rotary valve.

[0020] According to a sixteenth aspect of the present invention, the rotary disk apertures are configured to have a rotation angle that does not overlap any of the fixed disk apertures when the rotary disk rotates, and the fixed disk apertures that guide air to the multiple outlets are blocked by adjusting the rotation angle of the rotary disk, thereby making it possible to stop the air blowing. According to the sixteenth aspect of the present invention, when blowing is not performed, the outlets can be blocked and the branch pipes can be shut off by adjusting the rotation angle of the rotary disk so that all of the fixed disk apertures are blocked by the rotary disk.

[0021] The present invention as set forth in claim 17 is characterized by employing at least one of the following: a cooling water passage for cooling the rotary valve is provided in the outer casing; and the rotating disk is biased against the fixed disk by providing axial freedom with respect to the shaft. According to the present invention as set forth in claim 17, performance degradation such as increased leakage from the rotary valve, which is a concern when high-temperature air is supplied from the air supply means, can be prevented by either cooling the rotary valve with cooling water to suppress temperature increases, or by biasing the rotating disk against the fixed disk to suppress expansion of the gap between the rotating disk and the fixed disk when temperature increases.

[0022] The present invention as set forth in claim 18 is characterized in that, in order to prevent eccentricity of the shaft due to rotation caused by uneven distribution of the rotating disk apertures, one of the following measures is taken: providing eccentricity prevention apertures of the same shape at symmetrical positions to the rotating disk apertures, performing eccentricity prevention counterbore machining of an approximately similar shape at symmetrical positions to the rotating disk apertures, or providing a counterweight near the rotating disk apertures. According to the present invention as set forth in claim 18, eccentricity of the shaft can be prevented when the rotating disk rotates by using any of the eccentricity prevention apertures, eccentricity prevention counterbore machining, or counterweight.

[0023] The present invention as set forth in claim 19 is characterized in that the internal space upstream of the rotary disk of the outer shell is configured to have a predetermined volume, thereby equalizing the pressure of the air entering from the inlet. According to the present invention as set forth in claim 19, by having the internal space have a predetermined volume, pressure fluctuations in the rotary valve and piping route can be suppressed.

[0024] According to the periodic air lubrication system of the present invention, the air supplied from the air supply means can be distributed by the rotary path switching means through branch pipes to each air outlet and then blown out from the bottom of the ship, thereby reducing the required installation space compared to when multiple air supply means and switching means are installed. Also, because the control means controls the rotation of the valve body of the rotary path switching means to blow air periodically and intermittently out of all the air outlets to the bottom of the ship, the number of components and electronic control devices can be reduced, thereby improving durability and maintainability compared to a configuration using multiple solenoid valves that open and close frequently.

[0025] Furthermore, when the rotary path switching means is configured to communicate with either of the branch pipes regardless of the rotation angle of the valve disc, the rotary path switching means is always in communication with the branch pipe that serves as a pressure relief route, which prevents the internal pressure of the rotary path switching means from increasing excessively and reduces increases in rotational torque and air leakage, etc. Furthermore, since the pipe path is not closed during cyclic air blowout, the operation of the air supply means is stable.

[0026] In addition, when the rotary path switching means is configured to be able to adjust the duty ratio, which is the time ratio between air being blown out from the air outlet and the time when air is not being blown out, and the control means controls to change the duty ratio by rotating the valve body according to the mode setting of the air blowing mode, the control means controls to change the duty ratio set by the rotary path switching means according to the mode, thereby changing the blowing interval according to the navigation conditions of the ship and effectively reducing frictional resistance through air lubrication.

[0027] In addition, when the control means controls to change the rotational speed of the valve body of the rotary path switching means according to the mode setting of the air blowing mode, the blowing period can be changed by changing the rotational speed, and air can be blown out at a period according to each mode.

[0028] In addition, when the rotary path switching means has a configuration that allows communication between all of the multiple branch pipes, and the control means adjusts the rotation angle of the valve body of the rotary path switching means in accordance with the mode setting of the air blowing mode to control the continuous blowing of air from all of the air outlets, it is possible to switch between periodic blowing and continuous blowing with a single rotary path switching means by selecting the mode.

[0029] Furthermore, if the rotary path switching means has a configuration capable of blocking all of the multiple branch pipes, and the control means adjusts the rotation angle of the valve body of the rotary path switching means to control the blocking of all of the branch pipes when the air supply means is stopped, when blowing is not being performed, the branch pipes can be shut off by controlling the rotation angle of the valve body of the rotary path switching means to prevent, for example, water from flowing back from the air outlet to all of the branch pipes.

[0030] Furthermore, when the rotary path switching means has a configuration that allows it to select a predetermined branch pipe from among a plurality of branch pipes, and the control means controls the periodic supply of air from a predetermined air outlet by rotating or rotating the valve body forward or backward according to the mode setting of the air blowing mode, for example, in a mode in which periodic blowing is performed using the air outlet located toward the center of the hull when the hull is experiencing such large rolling motion that the air outlets located toward the side of the hull are exposed from the water, or in a mode in which periodic blowing is performed using all air outlets by alternately switching between the air outlets located on the left and right sides of the center of the hull when moderate rolling is occurring, the valve body can be rotated or rotated forward or backward so that air is distributed to the selected predetermined branch pipe, and periodic blowing according to each mode can be performed.

[0031] Furthermore, when the rotary path switching means is configured to be able to select a predetermined branch pipe from among a plurality of branch pipes, and the control means controls the supply of air from a predetermined air outlet by stopping the rotation of the valve body according to the mode setting of the air blowing mode, for example, when the hull is rolling to the extent that the air outlets located closer to the side of the hull are exposed from the water, in a mode in which continuous blowing is performed using the air outlets located closer to the center of the hull, continuous blowing according to the mode can be performed by fixing the rotation angle of the valve body so that air is distributed only to the selected predetermined branch pipe.

[0032] In addition, by adopting at least one of a cooling means and a temperature rise prevention structure to prevent the temperature rise of the rotary path switching means due to the supply of heated air from the air supply means, it is possible to prevent performance degradation such as increased leakage from the rotary path switching means due to temperature rise.

[0033] Furthermore, according to the rotary valve for a periodic air lubrication system of the present invention, by rotating the rotating disk, the rotating disk apertures overlap with the fixed disk apertures in a predetermined order, and the air passes through the fixed disk apertures that overlap with the rotating disk apertures, flows into the branch pipe, and is blown out from the air outlet, so that air can be supplied periodically from multiple outlets with a simple configuration.

[0034] Furthermore, when a single rotating disk aperture is configured in a shape that overlaps at least one of the multiple fixed disk apertures regardless of the rotation angle, the rotating disk aperture will always overlap one of the fixed disk apertures, and the rotary valve will always be in communication with the branch pipe, which serves as a pressure escape route, thereby preventing the internal pressure of the rotary valve from increasing excessively and reducing increases in rotational torque and air leakage, etc.

[0035] Furthermore, if the rotary valve is configured so that the rotary disk can be replaced with another rotary disk as a valve body having another rotary disk opening of a different shape than the rotary disk opening, and the duty ratio is made variable, the duty ratio can be changed by replacing the rotary disk with another rotary disk having a different shape of the rotary disk opening.

[0036] In addition, an adjustment disk for adjusting the duty ratio is further provided, and the overlapping apertures formed by the overlapping of the rotating disk apertures and the adjustment disk apertures of the adjustment disk, or the overlapping of the adjustment disk apertures and the fixed disk apertures, are configured to be changeable. When the duty ratio is variable, the size of the overlapping apertures formed by the overlapping of the rotating disk apertures and the adjustment disk apertures, or the adjustment disk apertures and the fixed disk apertures, can be changed by changing the position of the adjustment disk, thereby changing the duty ratio.

[0037] Furthermore, if the drive speed of the drive means for driving the rotary disk to rotate is made variable, the blowing period can be changed by changing the rotation speed of the rotary disk.

[0038] Furthermore, if the rotating disk apertures are configured to have a rotation angle that covers all of the multiple fixed disk apertures when the rotating disk rotates, and the multiple fixed disk apertures that direct air to multiple outlets are connected by adjusting the rotation angle of the rotating disk, allowing air to be blown out continuously, then it is possible to switch between periodic blowing and continuous blowing with a single rotary valve.

[0039] In addition, if the rotating disk apertures are configured to have a rotation angle that does not overlap any of the multiple fixed disk apertures when the rotating disk rotates, and the multiple fixed disk apertures that direct air to multiple outlets are blocked by adjusting the rotation angle of the rotating disk, and the air blowing can be stopped, when blowing is not being performed, the outlets can be blocked and the branch pipes can be shut off by adjusting the rotation angle of the rotating disk so that all of the fixed disk apertures are blocked by the rotating disk.

[0040] Furthermore, when at least one of the following is adopted: a passage for cooling water to cool the rotary valve is provided in the outer casing; and the rotating disk is biased against the fixed disk by allowing axial freedom relative to the shaft, performance degradation such as increased leakage from the rotary valve, which is a concern when high-temperature air is supplied from the air supply means, can be prevented by either cooling the rotary valve with cooling water to suppress temperature rise, or by biasing the rotating disk against the fixed disk to suppress the expansion of the gap between the rotating disk and the fixed disk when temperature rises.

[0041] Furthermore, in order to prevent eccentricity of the shaft due to rotation caused by the uneven distribution of the rotating disk openings, if any of the following measures are taken: providing eccentricity prevention openings of the same shape at symmetrical positions of the rotating disk openings on the rotating disk, performing eccentricity prevention countersinking of an approximately similar shape at symmetrical positions of the rotating disk openings, or providing a counterweight near the rotating disk openings, then eccentricity of the shaft when the rotating disk rotates can be prevented by any of the eccentricity prevention openings, eccentricity prevention countersinking, or counterweight.

[0042] Furthermore, if the internal space upstream of the outer rotating disk is configured to have a predetermined volume and the air entering through the inlet is pressure-equalized, the internal space having a predetermined volume can suppress pressure fluctuations in the rotary valve and piping route.

[0043] Schematic diagram of a periodic air lubrication system in an embodiment of the present invention; Schematic diagram of a rotary valve for the periodic air lubrication system; Figure showing an example of a configuration provided with a cooling means and a temperature rise countermeasure structure; Figure showing the overlap of the rotating disk apertures and the fixed disk apertures; Figure relating to the shape of the rotating disk apertures; Figure showing an example of a configuration in which the duty ratio can be adjusted; Figure showing an example of a configuration in which the duty ratio can be automatically adjusted; Figure showing another example of the rotating disk; Figure showing yet another example of the rotating disk; Figure showing a method for controlling the rotating disk when the ship is experiencing a rolling motion of more than a predetermined level; Figure showing another method for controlling the rotating disk when the ship is experiencing a rolling motion of more than a predetermined level; Figure showing yet another example of the rotating disk; Figure relating to a periodic blowing test using a model

[0044] A periodic-blow air lubrication system and a rotary valve for the periodic-blow air lubrication system according to an embodiment of the present invention will be described. FIG. 1 is a schematic diagram of the periodic-blow air lubrication system according to this embodiment. The periodic-blow air lubrication system installed on a ship 1 periodically blows air onto the bottom of the ship 1 to reduce the frictional resistance of the hull. The system includes multiple air outlets 10 on the bottom of the ship, an air supply unit 20 such as an air blower that supplies air to the multiple air outlets 10 via a piping path 50, a rotary path switching unit 30 installed along the piping path 50, and a control unit 40 that controls the rotary path switching unit 30. The piping path 50 also includes a single main pipe 51 connecting the air supply unit 20 and the rotary path switching unit 30, and multiple branch pipes 52 downstream of the rotary path switching unit 30 that serve as the piping path 50 leading to the multiple air outlets 10. The rear side of the ship 1 is omitted in FIG. 1 . The air supply means 20 may be any means such as an air blower, a bypass extraction means from a turbocharger of the engine, or a combination of a bypass extraction means from a turbocharger and an air blower.

[0045] Each branch pipe 52 is provided in a one-to-one correspondence with an air outlet 10, with one end connected to the rotary path switching means 30 and the other end connected to the air outlet 10. Air sent from the air supply means 20 to the main pipe 51 is distributed by the rotary path switching means 30 to the predetermined branch pipes 52 and blown out from each air outlet 10. The rotary path switching means 30 is provided between the main pipe 51 and the branch pipes 52, and has an air inlet connected to the main pipe 51 and a plurality of air outlets connected to each branch pipe 52. The control means 40 controls the rotation of the rotary member (valve body) in the rotary path switching means 30 to switch the air outlets to be opened and closed in a predetermined order. This switches the air outlets 10 to which air is supplied in a predetermined order, and air is periodically blown out from the air outlets 10 toward the bottom of the ship. Note that FIG. 1 illustrates an image of the air bubble flow generated in the case of periodic blowing, as well as an image of the air bubble flow generated in the case of continuous blowing, as described below. Periodic blowing can achieve a greater reduction in frictional resistance than continuous blowing, even when the blown air volume is the same. Furthermore, because the air supplied from the air supply means 20 is distributed to each air outlet 10 via the branch pipes 52 by the rotary path switching means 30 and then blown out from the ship's bottom, the required installation space can be reduced compared to installing multiple air supply means 20 and switching means. Periodic blowing can also be performed using a configuration using solenoid valves to control the air flow rate, but this configuration raises concerns about electronic control problems and durability. In contrast, the periodic blowing air lubrication system of this embodiment is configured so that air is blown out periodically and intermittently from all air outlets 10 toward the ship's bottom by the control means 40 controlling the rotation of the valve element of the rotary path switching means 30. This allows the only electronic control device to be a drive means, such as a motor, that rotates the valve element of the rotary path switching means 30. This reduces the number of components and electronic control devices compared to a configuration using multiple solenoid valves that frequently open and close, thereby improving durability and maintainability.

[0046] 2A and 2B are schematic diagrams of a rotary valve for a periodic air lubrication system, in which Fig. 2A shows the overall configuration, Fig. 2B shows the rotating disk, and Fig. 2C is a cross-sectional view taken along line A-A in Fig. 2A and showing the fixed disk. In this embodiment, a rotary valve is used as the rotary path switching means 30. This rotary valve 30 for a periodic-blow air lubrication system includes an outer shell (casing) 31 having an air inlet (air inlet) 31A and multiple outlets (air outlets) 31B, a rotating disk 32 serving as a rotating member (valve element) housed in the outer shell 31 on the outlet 31B side and having a single rotating disk opening 32A between its center and outer edge, a fixed disk 33 serving as a valve seat having multiple fixed disk openings 33A between its center and outer edge along which the rotating disk 32 slides to guide air to the multiple outlets 31B, a biasing means 34 for pressing the rotating disk 32 against the fixed disk 33, and a driving means 36 for rotationally driving the rotating disk 32 via a shaft 35A. A rotating disk shaft hole 32B and a fixed disk shaft hole 33B, through which a shaft (driven shaft) 35A is passed, are formed in the center of the rotating disk 32 and the center of the fixed disk 33, respectively. The shaft 35A on the rotating disk side is connected to the drive shaft 35B of the drive means 36 via a coupling 38, and the connection portion is covered with a shaft cover 37. The coupling 38 is a slotted coupling (eccentric coupling) with circumferential slits on its outer periphery, which eliminates eccentricity between the shaft 35A and the drive shaft 35B. To improve rotational stability, the shaft 35A is supported at two points by bearings 39 provided on the rotating disk 32 side and the coupling 38 side, respectively. By rotating the rotating disk 32, the rotating disk openings 32A overlap with the fixed disk openings 33A in a predetermined order. Air passes through the fixed disk openings 33A that overlap with the rotating disk openings 32A, flows into the branch pipe 52, and is then blown out from the air outlet 10. This simple configuration allows air to be periodically supplied from multiple outlets 31B.

[0047] The gap between the rotating disk 32 and the fixed disk 33 is approximately 0.2 mm. The temperature of the compressed air supplied from the air supply means 20 depends on the pressure, but is expected to be approximately 100°C for a coastal vessel with a draft of approximately 5 meters and exceed 200°C for a large ocean-going vessel with a draft of 20 meters. When the portion of the shaft 35A that rotates the rotating disk 32 located in the gap between the rotating disk 32 and the fixed disk 33 expands due to temperature changes, the size of the gap changes. Depending on the dimensions of the expanding portion, the gap may change by approximately 0.1 mm with a temperature change of 100°C. Therefore, the shaft 35A is given axial freedom, and the fitting structure between the shaft 35A and the rotating disk 32 is keyed, for example, to allow for free forward and backward movement but not rotation. Furthermore, a spring or other biasing means 34 biases the rotating disk 32 toward the fixed disk 33, thereby preventing the gap from widening when the shaft 35A expands due to temperature changes. This temperature rise countermeasure structure maintains the size of the gap within a predetermined range, allowing the rotary valve 30 to perform as designed. Furthermore, the biasing mechanism 34 biases the gap within a predetermined range, even when subjected to temperature changes and wear over time. The shaft 35A, the rotating disk 32, and the fixed disk 33 can be made of ceramics or other materials with low thermal expansion coefficients, or a combination of materials and structures can be used. The rotating disk 32 and the fixed disk 33 can be configured in any shape other than circular, as long as they are functional. The fixed disk 33 can also serve as the outer shell 31. In this embodiment, a so-called flat-type rotary valve consisting of the rotating disk 32 (valve element) and the fixed disk 33 is used as the rotary path switching mechanism 30. However, other valves, such as cylinder-type and ball-type valves, can also be used as the rotary path switching mechanism 30.

[0048] Another solution to the problem of the gap between the rotating disk 32 and the fixed disk 33 increasing due to the inflow of high-temperature air is to provide a cooling means to suppress the temperature rise and thereby inhibit the elongation of the shaft 35A. Figures 3A and 3B show configuration examples in which a cooling means and a temperature rise prevention structure are provided, with Figure 3A showing a first configuration example and Figure 3B showing a second configuration example. In the first configuration example shown in Figure 3A, a first water-cooled heat exchanger 90A is provided in the main pipe 51 upstream of the rotary valve 30 as the cooling means. A fresh cooling water circulation pipe 91, through which fresh water (fresh cooling water) flows as cooling water, passes through the first water-cooled heat exchanger 90A. Air supplied from the air supply means 20 is cooled as it passes through the first water-cooled heat exchanger 90A and enters the rotary valve 30. This prevents the temperature rise of the rotary valve 30 due to the inflow of air. The portion of the fresh cooling water circulation pipe 91 that extends outside the first water-cooled heat exchanger 90A passes through a second water-cooled heat exchanger 90B. A cooling seawater pipe 92 through which cooling seawater (cooling seawater) flows is disposed in the second water-cooled heat exchanger 90B. The cooling water, whose temperature has increased due to heat exchange with the air flowing through the main pipe 51, exits the first water-cooled heat exchanger 90A, is cooled in the second water-cooled heat exchanger 90B, and then flows back to the first water-cooled heat exchanger 90A. In the second configuration example shown in FIG. 3( b), a cooling water passage 100 is provided in the outer casing 31 of the rotary valve 30 as a temperature rise countermeasure structure, extending from the air inlet 31A side to the outlet 31B side. One end of the fresh cooling water pipe 101 is connected to a cooling water inlet 100A provided on the inlet 31A side of the passage 100, and the other end of the fresh cooling water pipe 101 is connected to a cooling water outlet 100B provided on the outlet 31B side. Fresh water (cooling fresh water) flows through a passage 100 provided in the outer shell 31 to cool the rotary valve 30, thereby suppressing a temperature rise in the rotary valve 30 due to the inflow of high-temperature air. The cooling fresh water pipe 101 passes through a water-cooled heat exchanger 102.A cooling seawater pipe 103 through which cooling seawater (cooling seawater) flows is disposed in the water-cooled heat exchanger 102. The cooling water, whose temperature has risen due to heat exchange with the air flowing through the rotary valve 30, flows out of a cooling water outlet 100B into a fresh cooling water pipe 101, is cooled in the water-cooled heat exchanger 102, and then flows back into the passage 100 through a cooling water inlet 100A. The use of the second water-cooled heat exchanger 90B and the water-cooled heat exchanger 102 prevents the deposition of scale and corrosion on the first water-cooled heat exchanger 90A and the outer shell 31 due to seawater (cooling seawater), thereby ensuring the reliability of the complex rotary valve 30 and surrounding structures. Furthermore, when deposition of corrosion scale progresses on the second water-cooled heat exchanger 90B or the water-cooled heat exchanger 102, the second water-cooled heat exchanger 90B or the water-cooled heat exchanger 102 can be replaced, thereby avoiding the need to replace the rotary valve 30 or surrounding structures.

[0049] Although not shown, the cooling means can be configured as follows in addition to the first and second configuration examples described above. Third Configuration Example: The basic configuration is the same as the first configuration example, but a water-cooled heat exchanger (corresponding to the first water-cooled heat exchanger 90A) provided in the main pipe 51 upstream of the rotary valve 30 has a cooled seawater circulation pipe through which seawater flows, and differs from the first configuration example in that seawater is used as the cooling water instead of fresh water. Fourth Configuration Example: An air-cooled heat exchanger is provided in the main pipe 51 upstream of the rotary valve 30 as the cooling means, and air supplied from the air supply means 20 is cooled as it passes through the air-cooled heat exchanger and enters the rotary valve 30, thereby suppressing a temperature rise in the rotary valve 30. Fifth Configuration Example: A fan is provided as the cooling means, blowing gas such as air toward the main pipe 51 upstream of the rotary valve 30, and air supplied from the air supply means 20 is cooled as it passes through the fan's installation point and enters the rotary valve 30, thereby suppressing a temperature rise in the rotary valve 30. Sixth configuration example: As a cooling means, a cooling water pipe through which cooling water flows is provided near the main pipe 51 on the upstream side of the rotary valve 30, and air supplied from the air supply means 20 is cooled as it passes through the cooling water pipe and enters the rotary valve 30, thereby suppressing a temperature rise in the rotary valve 30. The cooling water pipe can also be arranged so as to be wrapped around the outer periphery of the main pipe 51. Seventh configuration example: As a cooling means, a cooling water injection pipe is connected to the main pipe 51 on the upstream side of the rotary valve 30, and air supplied from the air supply means 20 is cooled by the cooling water sprayed from the cooling water injection pipe and enters the rotary valve 30. Eighth configuration example: As a cooling means for cooling the rotary valve 30, a fan that blows gas such as air toward the outer casing 31 is provided, thereby suppressing a temperature rise in the rotary valve 30. Ninth configuration example: A cooling water tank having a water-cooled heat exchanger is provided as a cooling means, and the main pipe 51 upstream of the rotary valve 30 passes through this cooling water tank. The air supplied from the air supply means 20 is cooled as it passes through the installation location of the cooling water tank and enters the rotary valve 30, thereby suppressing the temperature rise of the rotary valve 30.An in-tank cooling water circulation pipe through which cooling water such as seawater flows passes through the water-cooled heat exchanger inside the cooling water tank, and the cooling water flowing through this cooling water circulation pipe is cooled by another water-cooled heat exchanger or air-cooled heat exchanger installed outside the tank.

[0050] In this way, by adopting at least one of a cooling means and a temperature rise prevention structure as a countermeasure against the temperature rise of the rotary valve 30 due to the supply of heated air from the air supply means 20, it is possible to prevent performance degradation such as increased leakage from the rotary valve 30.

[0051] A chamber (air chamber) 31C is provided within the outer shell 31 between the inlet 31A and the rotary disk 32. While the chamber 31C shown in FIG. 2 gradually expands from the upstream side to the downstream side, it may also have a shape with a substantially constant diameter from the upstream side to the downstream side. By providing the chamber 31C in this way and configuring the internal space upstream of the rotary disk 32 of the outer shell 31 to have a predetermined volume, and by equalizing the pressure of the air entering through the inlet 31A, pressure fluctuations in the rotary valve 30 and the piping path 50 can be suppressed. Furthermore, the internal pressure in the rotary valve 30 can be maintained within a predetermined pressure range, allowing for quantitative intermittent blowing of air from each air outlet 10.

[0052] The drive means 36 is a variable rotational speed motor, and is capable of changing the drive speed at which the rotary disk 32 is rotated. The control means 40 controls the change of the rotational speed of the rotary disk 32 by changing the drive speed of the drive means 36 in accordance with the air blowing mode setting. By changing the rotational speed of the rotary disk 32, the blowing cycle can be changed, and air can be blown out at a cycle corresponding to each mode. Note that the mode settings include a mode in which air is blown out periodically at a standard cycle, a mode in which air is blown out periodically at a cycle longer than the standard cycle, and a mode in which air is blown out periodically at a cycle shorter than the standard cycle.

[0053] FIG. 4 shows the overlap between the rotating disk apertures and the fixed disk apertures. The fixed disk 33 has four circular fixed disk apertures 33A spaced 90 degrees apart around the circumference, while the rotating disk 32 has one elongated rotating disk aperture 32A extending over a quarter of the circumference (0 to 90 degrees). By shaping the single rotating disk aperture 32A so that it overlaps at least one of the multiple fixed disk apertures 33A regardless of the rotation angle of the rotating disk 32, the rotating disk 32 can be configured to communicate with one of the branch pipes 52 regardless of the rotation angle of the rotating disk 32. As described above, the air lubrication system can also be configured using a solenoid valve, but in that case, there is a concern about abnormal increases in transient internal pressure of the solenoid valve due to the opening and closing of the solenoid valve. In contrast, in the rotary valve 30 of the periodic air lubrication system of this embodiment, the rotating disk aperture 32A always overlaps with one of the fixed disk apertures 33A during periodic air blowing, so that the rotary valve 30 is always in communication with the branch pipe 52, which serves as a pressure escape route, preventing an excessive increase in internal pressure and reducing increases in rotational torque and air leakage, etc. Furthermore, because the pipe path 50 is not closed during periodic air blowing, the operation of the air supply means 20 is stable.

[0054] Figure 5 is a diagram related to the shape of the rotating disk apertures, with Figure 5(a) showing three example shapes of the rotating disk apertures, and Figure 5(b) showing the change in flow rate of one air outlet during periodic blowing for each example shape of the rotating disk aperture. The rotating disk aperture 32A can also have a shape other than that shown in Figure 4. The rotating disk aperture 32A on the left side of Figure 5(a) is an example of a shape with the outer and inner edges having the same curvature and straight ends, the central rotating disk aperture 32A is an example of a shape with the outer and inner edges having the same curvature and curved ends, and the right rotating disk aperture 32A is an example of a shape with the outer edge having a smaller curvature than the inner edge and curved ends. In Fig. 5(b), line α represents the change in flow rate for the rotary disk opening 32A on the left side of Fig. 5(a), line β represents the change in flow rate for the rotary disk opening 32A in the center of Fig. 5(a), and line γ represents the change in flow rate for the rotary disk opening 32A on the right side of Fig. 5(a). As shown in Fig. 5(b), the duration of the peak air flow rate at one outlet 31B can be varied depending on the shape of the rotary disk opening 32A.

[0055] The rotary valve 30 is configured to have an adjustable duty ratio. The duty ratio is the ratio of the time during which air is blown out from the air outlet 10 to the time during which air is not blown out. For example, if the time during one cycle during which air is blown out is 25% and the time during which air is not blown out is 75% the duty ratio is 0.25. To make the duty ratio adjustable, for example, the rotary valve 30 is configured so that the rotary disk 32 is replaceable, and multiple rotary disks 32 with different shapes of rotary disk openings 32A are prepared. Because the duty ratio can change depending on the shape of the rotary disk openings 32A, the duty ratio can be changed by replacing a rotary disk 32 having a certain shape of rotary disk openings 32A with a rotary disk 32 having a different shape of rotary disk openings 32A.

[0056] 6A and 6B show another example of a configuration capable of adjusting the duty ratio. FIG. 6A shows a rotary valve equipped with an adjusting disk, FIG. 6B shows a state in which the rotating disk aperture and the adjusting disk aperture are partially overlapping, FIG. 6C shows an example of how the rotating disk and the adjusting disk are combined, and FIG. 6D shows another example of how the rotating disk and the adjusting disk are combined. In this example, an adjusting disk 60 for adjusting the duty ratio is provided facing the surface of the rotating disk 32 opposite the surface facing the fixed disk 33. The adjusting disk 60 is the same size as the rotating disk 32 and has an adjusting disk aperture 60A. In its center, an adjusting disk shaft hole 60B through which the shaft 35A passes is formed. The adjusting disk aperture 60A has an elongated shape similar to the rotating disk aperture 32A, and is the same size as the rotating disk aperture 32A. The adjustment disk opening 60A can be different in shape and size from the rotary disk opening 32A. The rotation angle of the rotary disk 32 and the adjustment disk 60 can be set at predetermined intervals, such as 30 degrees, and can be changed by disassembling the rotary valve 30 and fixing it at the new rotation angle using a fastener such as a dowel or pin. By making the rotation angle of the adjustment disk 60 different from that of the rotary disk 32 and blocking a portion of the rotary disk opening 32A with the adjustment disk 60, the duty ratio can be changed, for example, by reducing the duty ratio to half that when the rotary disk 32 is used alone, as shown in FIG. 6. Furthermore, the size of the overlapping aperture formed by the overlap of the rotating disk aperture 32A and the adjusting disk aperture 60A can be changed depending on the degree of overlap between the rotating disk aperture 32A and the adjusting disk aperture 60A, and therefore the duty ratio can be changed by changing the size of the overlapping aperture by changing the position (rotation angle) of the adjusting disk 60. For example, Figure 6(c) shows an example in which a single rotating disk key groove 32F is provided on the periphery of the rotating disk axial hole 32B in the rotating disk 32, and multiple adjusting disk key grooves 60C are provided on the periphery of the adjusting disk axial hole 60B in the adjusting disk 60. The size of the overlapping aperture changes depending on which adjusting disk key groove 60C is aligned with the position of the rotating disk key groove 32F, and therefore the duty ratio can be changed by selecting the adjusting disk key groove 60C that is keyed together with the rotating disk key groove 32F.6(d) shows an example in which a single anti-spinning rotary disk key groove 32F is provided around the periphery of the rotary disk shaft hole 32B in the rotary disk 32, multiple pin holes 32G are provided in positions where no rotary disk opening 32A is provided, and a single pin 60D is provided in a position where no adjustment disk shaft hole 60B is provided in the adjustment disk 60. Since the size of the overlapping opening changes depending on which pin hole 32G the pin 60D is inserted into, the duty ratio can be changed by selecting the pin hole 32G into which the pin 60D is inserted.

[0057] FIG. 7 shows an example of a configuration capable of automatically adjusting the duty ratio. A possible configuration for automatically controlling and adjusting the duty ratio externally is, for example, as shown in FIG. 6 , in which the adjustment disk 60, the rotating disk 32, and the fixed disk 33 are stacked, a stepping motor 70 is installed inside the shaft 35A, and the position (rotation angle) of the adjustment disk 60 is controlled by an external signal to adjust the overlapping apertures. In this case, the stepping motor 70 stops rotating the adjustment disk 60 when a predetermined overlapping aperture is obtained and holds the position fixed. Furthermore, by driving the rotating disk 32 with the driving means 36, the adjustment disk 60 also rotates together while maintaining the size of the overlapping apertures. A slip ring 71 that supplies power to the stepping motor 70 is attached to the shaft 35A, and the stepping motor 70 is covered by a protective case 80 formed from part of the shaft 35A. An AC power source is connected to the driving means 36, and a DC power source is connected to the slip ring 71. While FIG. 6 shows an example in which the adjustment disk 60, the rotating disk 32, and the fixed disk 33 are stacked in this order, it is also possible to reverse the order of the rotating disk 32 and the adjustment disk 60 and stack them in the order of the rotating disk 32, the adjustment disk 60, and the fixed disk 33, i.e., to provide the adjustment disk 60 between the rotating disk 32 and the fixed disk 33. Furthermore, with this order, it is possible to change the size of the overlapping aperture formed by the overlap of the adjustment disk aperture 60A of the adjustment disk 60 and the fixed disk aperture 33A of the fixed disk 33 by rotating the adjustment disk 60. In this case, after adjusting the position (rotation angle) of the adjustment disk 60 to adjust the size of the overlapping aperture, the adjustment disk 60 is held fixed by the stepping motor 70, and only the rotating disk 32 rotates. Incidentally, the duty ratio can also be controlled externally by using a structure in which the rotation axes of the rotating disk 32 and the adjustment disk 60 are dual-axis and the rotation angle can be changed by the stepping motor 70. Furthermore, a servo motor, a solenoid, or the like can be used as a means for driving the adjustment disk 60 in addition to the stepping motor 70. Furthermore, the shape of the adjustment disk 60 can be any shape other than a circle as long as it can perform its function.

[0058] In this way, the rotary valve 30 is configured to be able to adjust the duty ratio, which is the time ratio between air blowing and air blowing stop from the air outlet 10. The control means 40 performs control to change the duty ratio, for example, by changing the rotational angles of the rotary disk 32 and the adjustment disk 60, depending on the air blowing mode setting. By having the control means 40 perform control to change the duty ratio set in the rotary valve 30 depending on the mode, it is possible to change the blowing interval depending on the navigation conditions of the ship 1, and effectively reduce frictional resistance through air lubrication.

[0059] 8A and 8B show another example of a rotating disk, with Fig. 8A showing the rotation angle when continuous blowing is performed and Fig. 8B showing the rotation angle when cyclic blowing is performed. In this example, a fixed disk 33 has four circular fixed disk apertures 33A formed at 90-degree intervals on its outer periphery, while a single elongated rotating disk aperture 32A is formed on the outer periphery of a rotating disk 32, spanning three-quarters of the circumference (0 to 270 degrees). The minor axis of the rotating disk aperture 32A is preferably equal to or greater than the diameter of the fixed disk aperture 33A, and in this example, it is larger than the diameter of the fixed disk aperture 33A. In the periodic blowing mode, as shown in Fig. 8(b), the control means 40 rotates the rotary disk 32 in one direction so that the rotary disk apertures 32A overlap with three fixed disk apertures 33A but not with one fixed disk aperture 33A, thereby sequentially pausing the supply of air to each of the branch pipes 52 and enabling periodic blowing. On the other hand, in the continuous blowing mode, as shown in Fig. 8(a), the control means 40 stops the rotation of the rotary disk 32 when the rotary disk apertures 32A completely overlap with two fixed disk apertures 33A and only partially overlap with the remaining two fixed disk apertures 33A, thereby continuously supplying air to all of the branch pipes 52 and enabling continuous blowing from all of the air outlets 10. In this way, the rotating disk aperture 32A is configured to have a rotation angle that corresponds to all of the multiple fixed disk apertures 33A, and by adjusting the rotation angle of the rotating disk 32, the multiple fixed disk apertures 33A that direct air to the multiple outlets 31B are connected, and air can be blown out continuously.By this configuration, it is possible to switch between periodic blowing and continuous blowing with a single rotary valve 30 by selecting the mode.

[0060] FIG. 9 shows yet another example of a rotating disk. In this example, two rotating disks 32 are provided. The fixed disk 33 has four circular fixed disk apertures 33A formed at 90-degree intervals around the circumference, while the two rotating disks 32 each have one elongated rotating disk aperture 32A spanning a quarter of the circumference (0 to 90 degrees). The minor axis of the rotating disk aperture 32A is equal to or greater than the diameter of the fixed disk aperture 33A. In the periodic blowing mode, the control means 40 rotates the rotating disks 32 in a state in which the rotating disk aperture 32A of one rotating disk 32 overlaps with the rotating disk aperture 32A of the other rotating disk 32. On the other hand, when the operation of the air supply means 20 is stopped, the rotation angles of the rotary disks 32 are shifted by 180 degrees, for example, so that the rotary disk openings 32A of one rotary disk 32 do not overlap with the rotary disk openings 32A of the other rotary disk 32, thereby closing all of the branch pipes 52. In this way, the rotary valve 30 has a configuration that can close all of the branch pipes 52, and the control means 40 controls the rotation angle of the rotary disk 32 to close all of the branch pipes 52 when the operation of the air supply means 20 is stopped, so that when blowing is not being performed, the rotation angle of the rotary disk 32 can be controlled to block the outflow of air to the branch pipes 52 so as to prevent water from flowing back into all of the branch pipes 52 from the air outlets 10 and to prevent marine organisms from entering. It is also possible to configure the device so that the rotary disk aperture 32A of one rotary disk 32 has a rotation angle that does not overlap any of the fixed disk apertures 33A, and the fixed disk apertures 33A can be closed by adjusting the rotation angle of the rotary disk 32. Even in this configuration, when air is not being blown out, the rotation angle of the rotary disk 32 can be adjusted so that all of the fixed disk apertures 33A are closed, thereby closing the outlet 31B and preventing air from flowing into the branch pipe 52.

[0061] 10A and 10B show a method of controlling the rotating disk when the ship is experiencing a rolling motion of a predetermined magnitude or greater, with Fig. 10A showing control when the rolling motion is "large" and Fig. 10B showing control when the rolling motion is "medium." The rotating disk 32 has one elongated rotating disk aperture 32A formed over one-quarter of the circumference (0 to 90 degrees), and the fixed disk 33 has four circular fixed disk apertures 33A formed at 90-degree intervals in the circumferential direction. If the four fixed disk openings 33A are designated as a first fixed disk opening 33Aa, a second fixed disk opening 33Ab, a third fixed disk opening 33Ac, and a fourth fixed disk opening 33Ad, the first fixed disk opening 33Aa and the fourth fixed disk opening 33Ad are connected to air outlets 10 provided closer to the sides of the ship, and the second fixed disk opening 33Ab and the third fixed disk opening 33Ac are connected to air outlets 10 provided closer to the center of the hull. When the ship 1 rolls significantly, the air outlets 10 located closer to the center of the hull are always underwater, but the air outlets 10 located closer to the sides may become exposed to the water. Therefore, when the degree of rolling is "large," the control means 40 rotates the rotating disk 32 forward and backward within a 90-degree range so that the first fixed disk aperture 33Aa and the fourth fixed disk aperture 33Ad are always closed and the second fixed disk aperture 33Ab and the third fixed disk aperture 33Ac alternately open and close, as shown in Figure 10(a). This allows air to be periodically blown out from the air outlets 10 connected to the second fixed disk aperture 33Ab and the third fixed disk aperture 33Ac. By blowing out air only from the air outlets 10 located near the center of the hull and underwater even when rolling is large, the reduction in the frictional resistance reduction effect due to air lubrication can be suppressed. In addition, when the degree of lateral sway is "medium," the control means 40 rotates the rotating disk 32 forward and backward within a range of 180 degrees so that the first fixed disk opening 33Aa and the second fixed disk opening 33Ab, and the third fixed disk opening 33Ac and the fourth fixed disk opening 33Ad alternately open and close, as shown in Figure 10 (b).This allows periodic air blowing to be performed using all of the air blowing ports 10 by alternately switching between the third fixed disk opening 33Ac and the fourth fixed disk opening 33Ad connected to the air blowing ports 10 located to the left of the center of the hull and the first fixed disk opening 33Aa and the second fixed disk opening 33Ab connected to the air blowing ports 10 located to the right of the center of the hull while restricting the flow rate at each air blowing port 10. Note that, depending on the shape of the rotating disk opening 32A, a configuration in which the flow rate at the air blowing ports 10 is not restricted may also be possible. Furthermore, by rotating in one direction rather than forward and reverse, it is also possible to alternately open and close the first fixed disk opening 33Aa and the second fixed disk opening 33Ab and the third fixed disk opening 33Ac and the fourth fixed disk opening 33Ad. In this way, the rotary valve 30 has a configuration that can select a predetermined branch pipe 52 from the plurality of branch pipes 52, and the control means 40 controls the rotary disc 32 to rotate or rotate forward and backward in accordance with the air blowing mode setting, thereby controlling the cyclical supply of air from a predetermined air outlet 10, thereby distributing air to the selected predetermined branch pipe 52 and performing cyclical blowing according to each mode. The degree of lateral shaking is determined, for example, by comparing the sensor value with a threshold value.

[0062] FIG. 11 illustrates another control method for the rotary disk when the ship is experiencing a predetermined or greater degree of rolling. In this control method, when the degree of rolling is "large," the control means 40 fixes the rotation angle of the rotary disk 32 so that the first fixed disk aperture 33Aa and the fourth fixed disk aperture 33Ad are normally closed and the second fixed disk aperture 33Ab and the third fixed disk aperture 33Ac are normally open. This allows air to be continuously blown out from the air outlets 10 connected to the second fixed disk aperture 33Ab and the third fixed disk aperture 33Ac. In this manner, the rotary valve 30 is configured to select a predetermined branch pipe 52 from among the multiple branch pipes 52, and the control means 40 stops the rotation of the rotary disk 32 in accordance with the setting of the air blowing mode, thereby controlling the supply of air from the predetermined air outlet 10, thereby achieving continuous blowing out according to the mode.

[0063] 12A shows another example of a rotating disk, in which Fig. 12A shows a rotating disk in which an eccentricity prevention hole is formed on the diagonal side of the rotating disk hole, Fig. 12B shows a rotating disk in which a counterbore (non-through hole processing) is performed on the diagonal side of the rotating disk hole, and Fig. 12C shows a rotating disk in which a counterweight is attached along the outer edge of the rotating disk hole. A rotating disk hole 32A formed in only one place on one side, away from the center of the rotating disk 32, may cause eccentricity. Therefore, in order to prevent eccentricity of the shaft due to rotation caused by the uneven distribution of the rotating disk openings 32A, it is preferable to take measures such as providing an eccentricity prevention opening 32C of the same shape as the rotating disk opening 32A at a symmetrical position in the rotating disk 32, as shown in Figure 12(a), or providing an eccentricity prevention counterbore 32D of a similar shape at a symmetrical position to the rotating disk opening 32A as shown in Figure 12(b), or providing a counterweight 32E near the rotating disk opening 32A as shown in Figure 12(c). By providing any of the eccentricity prevention opening 32C, the eccentricity prevention counterbore 32D, or the counterweight 32E, it is possible to prevent eccentricity of the shaft when the rotating disk 32 rotates.

[0064] FIG. 13 illustrates a periodic blowing test using a model. FIG. 13(a) shows the test results, and FIG. 13(b) shows the test. A test using a model was conducted to verify the present invention. The rotary path switching means 30 used in the test was a rotary valve including a rotating disk 32 serving as a valve element with one elongated rotating disk aperture 32A formed over a quarter of the circumference (0 to 90 degrees) and a fixed disk 33 with four circular fixed disk apertures 33A formed at 90-degree intervals around the circumference. The test conditions were as follows: the air flow rate Q supplied from the driving means (motor) 36 was 100 L / min, and the rotation speed n of the rotating disk 32 was 2 rps (=0.5 Hz). In FIG. 13(a), Q1 to Q4 represent the mass flow rates of the four air outlets 10, and Q represents the total mass flow rate. As a result of the test, it was confirmed that a periodic air blowout of 0.5 Hz or less was possible, and that substantially uniform intermittent air blowout from each air outlet 10 was possible, as shown in FIG. 13( a ).

[0065] The periodic air lubrication system according to the present invention is capable of switching between multiple air blowing methods and controlling the duty ratio, and by using periodic air blowing, it is possible to increase the effect of reducing frictional resistance through air lubrication while suppressing the power required for air blowing. The periodic air lubrication system and rotary valve for the periodic air lubrication system according to the present invention can be applied to air lubrication methods on actual ships, as well as to tests of air lubrication methods using models.

[0066] REFERENCE SIGNS LIST 1 Ship 10 Air blow-out port 20 Air supply means 30 Rotary path switching means (rotary valve for periodic blow-out air lubrication system) 31 Outer shell 31A Inlet 31B Outlet 32 ​​Rotating disc 32A Rotating disc opening 32C Eccentricity prevention opening 32D Eccentricity prevention counterbore 32E Counterweight 33 Fixed disc 33A Fixed disc opening 34 Urging means 35A Shaft 36 Driving means 40 Control means 50 Pipe path 52 Branch pipe 60 Adjusting disc 60A Adjusting disc opening 90A Cooling means 100 Cooling means (cooling water passage)

Claims

1. An air lubrication system which periodically blows air onto the bottom of a ship to reduce frictional resistance of the hull, comprising: a plurality of air outlets provided on the bottom of the ship; an air supply means which supplies air to the plurality of air outlets via a piping path; a rotary path switching means provided midway through the piping path; and a control means which controls the rotary path switching means, the system having a plurality of branch pipes as the piping path leading to the plurality of air outlets downstream of the rotary path switching means, the air outlets to which the air is supplied are switched in a predetermined order by the rotation of a valve body of the rotary path switching means, and the air can be periodically blown out from all of the plurality of air outlets by the rotation of the valve body of the rotary path switching means.

2. The periodic blow-off air lubrication system as described in claim 1, characterized in that the rotary path switching means is configured to connect to any of the branch pipes regardless of the rotation angle of the valve body.

3. The periodic air lubrication system as described in claim 1, characterized in that the rotary path switching means is configured to adjust a duty ratio, which is the time ratio between the air being blown out from the air outlet and the air being stopped being blown out, and the control means controls to change the duty ratio by rotating the valve body according to the mode setting of the air blowing mode.

4. The periodic blow-off air lubrication system as described in claim 1, characterized in that the control means controls to change the rotational speed of the valve body of the rotary path switching means depending on the mode setting of the air blow-off mode.

5. The periodic blow-out air lubrication system described in claim 1, characterized in that the rotary path switching means has a configuration capable of connecting all of the plurality of branch pipes, and the control means adjusts the rotation angle of the valve body of the rotary path switching means in accordance with the mode setting of the air blow-out mode, thereby controlling the air to be continuously blown out from all of the air blowing ports.

6. The periodic blow-off air lubrication system described in claim 1, characterized in that the rotary path switching means has a configuration capable of blocking all of the plurality of branch pipes, and the control means adjusts the rotation angle of the valve body of the rotary path switching means to control the blocking of all of the branch pipes when the operation of the air supply means is stopped.

7. The periodic air lubrication system of claim 1, characterized in that the rotary path switching means is configured to be able to select a predetermined branch pipe from among the plurality of branch pipes, and the control means controls the air to be periodically supplied from a predetermined air outlet by rotating or rotating forward and reverse the valve body according to the mode setting of the air blowing mode.

8. The periodic blow-out air lubrication system described in claim 2, characterized in that the rotary path switching means is configured to be able to select a predetermined branch pipe from among the plurality of branch pipes, and the control means controls the supply of the air from a predetermined air blow-out port by stopping the rotation of the valve body in accordance with the mode setting of the air blow-out mode.

9. A periodic blow-off air lubrication system as described in claim 1, characterized in that the temperature rise of the rotary path switching means caused by the supply of heated air from the air supply means is countered by adopting at least one of a cooling means and a temperature rise countermeasure structure.

10. A rotary valve used as a rotary type path switching means in a periodic blow-off air lubrication system as described in any one of claims 1 to 9, comprising: an outer shell having an air inlet and multiple outlets; a rotating disk as a valve body having a single rotating disk aperture contained within the outer shell; a fixed disk as a valve seat having multiple fixed disk apertures along which the rotating disk slides to guide the air to the multiple outlets; a biasing means for pressing the rotating disk against the fixed disk; and a driving means for rotating the rotating disk via a shaft.

11. A rotary valve for a periodic blow-off air lubrication system as described in claim 10, which is derived from claim 2, characterized in that the single rotating disk aperture is configured in a shape that overlaps with at least one of the multiple fixed disk apertures regardless of the rotation angle.

12. A rotary valve for a periodic blow-off air lubrication system as described in claim 10, which recites claim 3, characterized in that the rotary valve is configured so that another rotating disk as the valve body having another rotating disk opening of a different shape from the rotating disk opening can be replaced with the rotating disk, making the duty ratio variable.

13. A rotary valve for a periodic blow-off air lubrication system as described in claim 10, which recites claim 3, further comprising an adjustment disk for adjusting a duty ratio, and configured so that an overlapping aperture formed by an overlap between the rotating disk aperture and an adjustment disk aperture of the adjustment disk, or an overlapping aperture formed by an overlap between the adjustment disk aperture and the fixed disk aperture, is changeable, thereby making the duty ratio variable.

14. A rotary valve for a periodic blow-off air lubrication system according to claim 10, which is derived from claim 4, characterized in that the drive speed of the drive means for rotating the rotary disk is variable.

15. A rotary valve for a periodic blow-off air lubrication system as described in claim 10, which cites claim 5, characterized in that the rotating disk aperture is configured to have a rotation angle that corresponds to all of the multiple fixed disk apertures when the rotating disk rotates, and the multiple fixed disk apertures that guide the air to the multiple outlets are connected by adjusting the rotation angle of the rotating disk, making it possible to blow out the air continuously.

16. A rotary valve for a periodic air lubrication system as described in claim 10, which cites claim 6, characterized in that the rotating disk aperture is configured to have a rotation angle that does not overlap any of the multiple fixed disk apertures as the rotating disk rotates, and the multiple fixed disk apertures that guide the air to the multiple outlets are blocked by adjusting the rotation angle of the rotating disk, thereby making it possible to stop the air from being blown out.

17. A rotary valve for a periodic blow-off air lubrication system as described in claim 10, which cites claim 9, wherein at least one of the following is adopted: a passage for cooling water for cooling the rotary valve is provided in the outer shell, and the rotating disk is biased against the fixed disk by providing a degree of axial freedom with respect to the shaft.

18. A rotary valve for a periodic blow-off air lubrication system as described in claim 10, characterized in that in order to prevent eccentricity of the shaft due to rotation caused by the uneven distribution of the rotating disk opening, one of the following measures has been taken: providing an eccentricity prevention opening of the same shape at a symmetrical position of the rotating disk opening of the rotating disk, performing eccentricity prevention countersinking of an approximate shape at a symmetrical position of the rotating disk opening, or providing a counterweight in the vicinity of the rotating disk opening.

19. A rotary valve for a periodic blow-off air lubrication system as described in claim 10, characterized in that the internal space of the outer shell upstream of the rotating disk is configured to have a predetermined volume, thereby equalizing the pressure of the air entering from the inlet.

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