Thrust gap measuring device, thrust gap measuring method and ship

Abstract

To provide a thrust gap measurement device and a thrust gap measurement method capable of measuring a thrust gap while the vessel is in operation without opening a marine double inversion propeller device, and a vessel.SOLUTION: A marine double inversion propeller device 100 comprises: an outer shaft 12 to which a front propeller 1 is fitted; an inner shaft 14 to which a rear propeller 2 is fitted; a double inversion thrust bearing 40 for transmitting a thrust force of the front propeller to the inner shaft; and a double inversion gear unit 20 that rotates the outer shaft and the inner shaft in opposite directions. The double inversion gear unit 20 has an inner shaft thrust bearing 50 that supports the thrust force of the inner shaft and holds its axial position. A thrust gap measurement device 60 comprises an inner shaft position sensor 62 that measures the axial advancing time inner shaft position F1 and the retreating time inner shaft position R1 of the inner shaft while the vessel is in operation, and a thrust gap calculation unit 66 that calculates a first thrust gasp C1 of the inner thrust bearing.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a thrust gap measuring device for a marine contra-rotating propeller device, a thrust gap measuring method, and a ship. [Background technology]

[0002] Marine contra-rotating propeller devices can be broadly divided into two types: two-shaft drive and single-shaft drive. In the two-shaft drive, the front and rear propellers are driven by two concentric shafts. In the single-shaft drive, a reversing mechanism is provided between the front and rear propellers, and both propellers are driven by a single shaft. Usually the front propeller is mounted on the rear end of the outer shaft, and the rear propeller is mounted on the rear end of the inner shaft. A system that rotates the inner and outer shafts in opposite directions is called a "contra-rotating gear system". Contra-rotating gear systems, whether twin-shaft or single-shaft drive systems, are usually located inside the hull of the ship.

[0003] A contra-rotating marine propeller device is provided with a contra-rotating thrust bearing and an inner shaft thrust bearing. The contra-rotating thrust bearing is provided between the outer shaft and the inner shaft to transmit the thrust force of the outer shaft to the inner shaft. The inner shaft thrust bearing is provided in the contra-rotating gear device to support the thrust force of the inner shaft and maintain the axial position of the inner shaft.

[0004] Such contra-rotating thrust bearings and inner shaft thrust bearings are disclosed in, for example, Patent Documents 1 and 2. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 5266542 [Patent Document 2] Patent No. 6532927 Summary of the Invention [Problem to be solved by the invention]

[0006] The contra-rotating thrust bearings and the inner shaft thrust bearing need to be inspected and repaired periodically to maintain their functionality.

[0007] Conventionally, inspection of contra-rotating thrust bearings has been carried out as follows. (1) As a means of understanding the condition of the contra-rotating thrust bearings of marine contra-rotating propeller equipment without overhauling the propeller system, the thrust clearance is measured and its changes over time are observed in addition to capturing foreign matter in the lubricating oil and identifying its components, thereby detecting abnormalities such as bearing damage and abnormal wear. (2) The thrust clearance is measured by pressing the shaft in the forward thrust direction and the reverse thrust direction using a hydraulic jack or the like during dock construction, measuring the distance between the inner shaft and the outer shaft (or the distance between the front and rear propellers), and calculating the difference.

[0008] However, the above-mentioned conventional inspection has the following problems. (1) Even if an abnormality occurs while a ship is operating, if the accumulation of foreign matter is minute, it cannot be detected by capturing foreign matter in the lubricating oil or by analyzing its components. (2) During docking work, which is carried out every few years, if an abnormality in the thrust clearance is detected through measurements in dry dock, open maintenance will be carried out from that point onwards, resulting in an unexpected extension of the construction period and causing significant adverse effects such as the need to review operation plans. (3) In particular, in the case of contra-rotating marine propeller devices for large ships, the forward / reverse movement of the shaft in dry dock increases the shaft weight, and the hydraulic jack used also becomes larger and heavier, making workability very poor.

[0009] Meanwhile, conventionally, thrust bearings (inner shaft thrust bearings) built into contra-rotating gear devices are subject to periodic overhaul maintenance. However, the above-mentioned inspection had the following problems. (1) In the case of small ships, the compartment in which the contra-rotating gear unit is located is narrow, making it difficult to work in open maintenance, which increases the construction period and cost. (2) In the case of large ships, the contra-rotating gear mechanism also becomes larger and heavier, which makes it difficult to perform overhaul work. This is a factor that increases the construction period and costs, just as in the case of small ships.

[0010] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a thrust gap measurement device, a thrust gap measurement method, and a ship equipped with the same, which are capable of measuring the thrust gap while the ship is operating without having to open up and maintain the marine contra-rotating propeller device. [Means for solving the problem]

[0011] According to the present invention, there is provided a thrust gap measurement device for a marine contra-rotating propeller device in which a front propeller and a rear propeller are arranged coaxially and rotate in opposite directions, comprising: The marine contra-rotating propeller device includes a hollow outer shaft having a rear end to which the front propeller is attached and supported rotatably around an axis thereof; an inner shaft having a rear end to which the rear propeller is attached and supported rotatably around the axis; A contra-rotating thrust bearing that transmits a thrust force acting on the front propeller to the inner shaft; a counter-rotating gear device that rotates the outer shaft and the inner shaft in opposite directions to each other, The contra-rotating gear device has an inner shaft thrust bearing that supports a thrust force of the inner shaft and maintains its axial position, The thrust gap measuring device is an inner shaft position sensor for measuring an inner shaft position F1 when moving forward and an inner shaft position R1 when moving backward in an axial direction of the inner shaft while the ship is in operation; An outer shaft position sensor that measures an outer shaft position F2 when moving forward and an outer shaft position R2 when moving backward in the axial direction of the outer shaft while the ship is in operation; a first thrust gap of the inner shaft thrust bearing and a second thrust gap of the contra-rotating thrust bearing. and a thrust gap calculation device that calculates the thrust gap.

[0012] According to the present invention, the above-mentioned thrust gap measuring device is used to While the ship is traveling, the forward inner shaft position F1 and the reverse inner shaft position R1 are measured; Calculate the first thrust gap of the inner shaft thrust bearing from the inner shaft position F1 during forward movement and the inner shaft position R1 during reverse movement. death, While the ship is traveling, the forward outer shaft position F2 and the reverse outer shaft position R2 are measured; calculating a second thrust gap of the contra-rotating thrust bearing from the forward movement inner shaft position F1, the reverse movement inner shaft position R1, the forward movement outer shaft position F2, and the reverse movement outer shaft position R2; A thrust clearance measurement method is provided. Effect of the Invention

[0013] According to the above-mentioned configuration of the present invention, the inner shaft position sensor measures the inner shaft position F1 during forward travel and the inner shaft position R1 during reverse travel while the ship is traveling. Also, the thrust clearance calculation device calculates the first thrust clearance of the inner shaft thrust bearing from the inner shaft position F1 during forward travel and the inner shaft position R1 during reverse travel. Therefore, the thrust clearance can be measured while the ship is operating, without having to open up the marine contra-rotating propeller device for maintenance. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a schematic plan view of a marine contra-rotating propeller device. [Diagram 2] FIG. 2 is a side cross-sectional view of the counter-rotating gear unit of FIG. [Diagram 3] 4A to 4C are explanatory diagrams of a thrust gap measuring method according to the present invention. [Figure 4] FIG. 4 is a schematic diagram showing detection data of an inner shaft position sensor and an outer shaft position sensor. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In addition, common parts in each drawing are given the same reference numerals, and duplicated explanations will be omitted.

[0016] The ship according to the present invention is equipped with the thrust gap measurement device 60 according to the present invention and the marine contra-rotating propeller device 100.

[0017] FIG. 1 is a schematic plan view of a marine contra-rotating propeller device 100. In this figure, a marine contra-rotating propeller device 100 is a device in which a front propeller 1 and a rear propeller 2 are arranged coaxially and rotate in opposite directions. The contra-rotating marine propeller device 100 includes an outer propeller shaft (hereinafter, “outer shaft 12 ”), an inner propeller shaft (hereinafter, “inner shaft 14 ”), a contra-rotating gear unit 20 , a drive unit 30 , and contra-rotating thrust bearings 40 . The outer shaft 12 is hollow, and the front propeller 1 is attached to the rear end thereof and supported rotatably about the axis. The inner shaft 14 has a rear propeller 2 attached to its rear end and is supported rotatably about its axis. Contra-rotating gear set 20 causes outer shaft 12 and inner shaft 14 to rotate in opposite directions. The contra-rotating gear set 20 has an inner shaft thrust bearing 50 that supports the thrust force of the inner shaft 14 and maintains its axial position. The drive unit 30 is a rotation drive source for the outer shaft 12 and the inner shaft 14 . The contra-rotating thrust bearing 40 transmits the thrust force acting on the front propeller 1 to the inner shaft 14 .

[0018] The outer shaft 12 is a hollow part, and is installed so as to penetrate the stern tube 3 provided in the hull 90. A front bush 5 and a rear bush 6 are provided between the stern tube 3 and the outer shaft 12, thereby rotatably supporting the outer shaft 12 on the hull 90. In order to prevent leakage of lubricating oil in the stern tube 3 to the engine room side, a bow side stern tube seal device 7 is provided on the bow side end face of the stern tube 3. In order to prevent leakage of lubricating oil in the stern tube 3 to the seawater side, a stern side stern tube seal device 8 is provided on the stern side end face of the stern tube 3.

[0019] The front propeller 1 has a boss 13 in the center, and the bow-side end face of this boss 13 and the stern-side end face of the outer shaft 12 are connected and fixed by connecting means such as bolts. An outer shaft sleeve joint 16 is connected and fixed to the bow-side end face of the outer shaft 12.

[0020] A hollow outer intermediate shaft 17 is connected and fixed to the bow side end of the outer sleeve joint 16. The outer intermediate shaft 17 has a configuration that can be radially separated into a plurality of (two or more) parts so that auxiliary parts of the inner shaft 14 (such as the contra-rotating front seal device 37) can be maintained.

[0021] The inner shaft 14 is rotatably supported inside the outer shaft 12. The rear propeller 2 has a boss 15 in the center, and is fitted onto the rear end of the inner shaft 14 at the boss 15 and fixed to the inner shaft 14 by a propeller nut 39.

[0022] In the marine contra-rotating propeller device 100, a front radial bearing 35 and a rear radial bearing 36 are provided to rotatably support the inner shaft 14 by the outer shaft 12. In the configuration example of Fig. 1, the front radial bearing 35 is disposed between the outer shaft sleeve joint 16 and the inner shaft 14, and the rear radial bearing 36 is disposed between the boss of the front propeller 1 and the inner shaft 14. Note that the positions of the front radial bearing 35 and the rear radial bearing 36 are not limited to the positions described above, and may be, for example, between the front and rear ends of the outer shaft 12 and the inner shaft 14.

[0023] 1, the contra-rotating thrust bearing 40 is provided inside the boss 13 of the front propeller 1. More specifically, an annular recess 13a is formed between the boss 13 of the front propeller 1 and the outer shaft 12, and the contra-rotating thrust bearing 40 is provided in this annular recess 13a. The contra-rotating thrust bearing 40 may be, for example, a tilting pad type thrust bearing.

[0024] In order to lubricate the front radial bearing 35, the rear radial bearing 36, and the contra-rotating thrust bearing 40, contra-rotating lubricating oil is supplied from a contra-rotating lubricating oil supply device (not shown) between the outer shaft 12 and the boss 13 of the front propeller 1, and the inner shaft 14. In order to prevent the contra-rotating lubricating oil from leaking out, a contra-rotating front seal device 37 is arranged on the bow end face of the outer shaft sleeve joint 16, and a contra-rotating rear seal device 38 is arranged on the stern end face of the boss 13 of the front propeller 1.

[0025] After lubricating the rear radial bearing 36, the contra-rotating lubricating oil passes through the gap between the seal liner of the contra-rotating rear seal device 38 and the inner shaft 14, and then passes through an oil passage hole 44 provided inside the boss 15 of the rear propeller 2. The lubricating oil then passes through the inside of a propeller cap 45 attached to the rear end of the boss 15, enters the hollow part of the inner shaft 14, passes through a seal device (not shown) provided at the bow side end of the shaft of the inner shaft output gear 29, and returns to a lubricating oil tank (not shown) installed in the engine room. The opening at the tip of the shaft of the inner shaft output gear 29 is closed by a stop flange 46.

[0026] 1, the drive unit 30 is composed of a first drive unit 31 which is a rotation drive source for the outer shaft 12, and a second drive unit 32 which is a rotation drive source for the inner shaft 14. The first drive unit 31 and the second drive unit 32 may be main engines such as gas turbine engines or diesel engines, or electric motors. In the case of electric motors, for example, one or more gas turbine generators or diesel generators may be installed in the engine room and used as the power source.

[0027] 1 is configured to transmit the rotational driving forces of a first drive unit 31 and a second drive unit 32 independently to an outer shaft 12 and an inner shaft 14. More specifically, the contra-rotating gear unit 20 has a housing 21, and is provided with an outer shaft transmission mechanism 18A and an inner shaft transmission mechanism 18B inside the housing 21.

[0028] The outer shaft transmission mechanism 18A has an outer shaft input gear 22 that is arranged coaxially with the output shaft 31a of the first driving device 31 and receives the driving force from the first driving device 31. The outer shaft transmission mechanism 18A further has a hollow outer shaft output gear 24 that is arranged coaxially with the outer shaft 12 and transmits the rotational driving force to the outer shaft 12, and an outer shaft intermediate gear 23 that is arranged between the outer shaft input gear 22 and the outer shaft output gear 24. The output shaft 31a of the first driving device 31 and the outer shaft input gear 22 are connected via a gear coupling 33a. Although there is one outer shaft intermediate gear 23 in FIG. 1, there may be multiple outer shaft intermediate gears 23.

[0029] The inner shaft transmission mechanism 18B has an inner shaft input gear 27 that is arranged coaxially with the output shaft 32a of the second driving device 32 and receives the driving force from the second driving device 32. The inner shaft transmission mechanism 18B further has an inner shaft output gear 29 that passes through the hollow part of the outer shaft output gear 24, is arranged coaxially with the inner shaft 14, and transmits the rotational driving force to the inner shaft 14, and an inner shaft intermediate gear 28 that is arranged between the inner shaft input gear 27 and the inner shaft output gear 29. The output shaft 32a of the second driving device 32 and the inner shaft input gear 27 are connected via a gear coupling 33b. Although there is one inner shaft intermediate gear 28 in FIG. 1, there may be multiple inner shaft intermediate gears 28. The inner shaft output gear 29 and the inner shaft 14 are connected and fixed by an inner shaft sleeve joint 26.

[0030] In the marine contra-rotating propeller device 100, the inner shaft thrust bearing 50 receives the thrust load from the inner shaft 14 (a combined load of the thrust load of only the inner shaft 14 and the thrust load of only the outer shaft 12) and transmits it to the hull 90. In Fig. 1, the inner shaft thrust bearing 50 is provided in the bow side portion of the housing 21 of the contra-rotating gear device 20. Therefore, the thrust load from the inner shaft 14 is supported by the hull 90 via the housing 21.

[0031] The position of the inner shaft thrust bearing 50 is not limited to the above-mentioned position as long as it can transmit the thrust load from the inner shaft 14 to the hull 90. Therefore, as long as it is located closer to the bow than the outer shaft output gear 24, it may be located inside the housing 21 or outside the housing 21.

[0032] In the configuration example of FIG. 1, both the outer shaft transmission mechanism 18A and the inner shaft transmission mechanism 18B are gear transmission mechanisms, but they may be planetary gear devices.

[0033] FIG. 2 is a cross-sectional side view of the counter-rotating gear unit 20 of FIG. In this figure, an inner shaft thrust bearing 50 has a self-aligning radial bearing 52 and a self-aligning thrust bearing 53. Also, 54 and 55 are radial roller bearings, and 56 is a self-aligning radial bearing.

[0034] The hollow central shaft 25A of the outer output gear 24 is supported by a radial roller bearing 55 and a self-aligning radial bearing 56 so as to be rotatable about the axis. The tip end (the left end in the figure) of the hollow central shaft 25A is connected to the outer intermediate shaft 17 via a gear coupling 19. In FIG. 1, the outer intermediate shaft 17 is connected to the outer shaft 12 via the outer sleeve joint 16. The connection between the outer shaft 12, the outer sleeve joint 16, and the outer intermediate shaft 17 is strong so that no gap occurs in the axial direction.

[0035] The central shaft 25B of the inner shaft output gear 29 is supported by an inner shaft thrust bearing 50 and a radial roller bearing 54 so as to be rotatable about its axis. In addition, in Fig. 1, the tip end (the left end in the figure) of the central shaft 25B is connected to the inner shaft 14 via an inner shaft sleeve joint 26. Note that the connection by the inner shaft sleeve joint 26 is strong and is designed so that no gap occurs in the axial direction.

[0036] In FIG. 2, a thrust gap measuring device 60 according to the present invention has an inner shaft position sensor 62, an outer shaft position sensor 64, and a thrust gap calculating device 66. The inner shaft position sensor 62 and the outer shaft position sensor 64 are preferably non-contact distance sensors fixed to fixed parts within the hull. The distance sensor preferably has a detection accuracy of 10 μm or less and a measurement range of 10 mm to 100 mm. As the distance sensor, for example, a laser displacement meter, an ultrasonic sensor, etc. can be used.

[0037] Moreover, the thrust gap calculation device 66 may be, for example, a computer (PC) having a storage device, a calculation device, an input device, and an output device.

[0038] The inner shaft position sensor 62 measures the inner shaft position F1 during forward travel and the inner shaft position R1 during reverse travel in the axial direction of the inner shaft 14 while the ship is traveling. The thrust gap calculation device 66 calculates the first thrust gap C1 of the inner shaft thrust bearing 50 from the forward drive inner shaft position F1 and the reverse drive inner shaft position R1. Further, the outer shaft position sensor 64 measures the outer shaft position F2 during forward travel and the outer shaft position R2 during reverse travel in the axial direction of the outer shaft 12 while the ship is traveling. The thrust gap calculation device 66 calculates the second thrust gap C2 of the contra-rotating thrust bearing 40 from the forward drive inner shaft position F1 and the reverse drive inner shaft position R1.

[0039] The first thrust gap C1 is the overall axial clearance of the inner shaft thrust bearing 50, that is, the self-aligning radial bearing 52 and the self-aligning thrust bearing 53. The first thrust gap C1 is, for example, 0.2 to 0.3 mm under normal conditions. The second thrust gap C2 is the entire axial clearance of the contra-rotating thrust bearing 40. The second thrust gap C2 is, for example, 2.0 to 2.6 mm under normal conditions.

[0040] FIG. 3 is an explanatory diagram of the thrust gap measuring method according to the present invention.

[0041] (Measurement of first thrust clearance C1) As described above, the inner shaft 14 and the central shaft 25B are connected via the inner shaft sleeve joint 26 so that no gap occurs in the axial direction. Therefore, when the ship is sailing forward, the thrust of the rear propeller 2 acts forward (to the right in the figure), and the central shaft 25B is pressed axially forward together with the inner shaft 14 and the inner shaft sleeve joint 26, so that the forward clearance of the inner shaft thrust bearing 50 becomes zero.

[0042] Similarly, when the ship is moving in reverse, the thrust of the rear propeller 2 acts rearward (to the left in the figure), so that the central shaft 25B is pressed axially rearward together with the inner shaft 14 and the inner shaft sleeve joint 26, and the rear clearance of the inner shaft thrust bearing 50 becomes zero.

[0043] The first thrust gap C1 of the inner shaft thrust bearing 50 is the sum of the front gap and the rear gap. Therefore, the difference in the front-rear direction between the forward movement inner shaft position F1 measured during forward movement and the reverse movement inner shaft position R1 measured during reverse movement (Δ1=F1−R1) corresponds to the first thrust gap C1 of the inner shaft thrust bearing 50.

[0044] The inner shaft position sensor 62 is fixed to a fixed portion inside the hull and detects, for example, the front end face of the central shaft 25B or the end face of the stop flange 46. In this case, the reference position (measurement origin) of the inner shaft position sensor 62 is set, for example, to the front end face of the central shaft 25B. However, the longitudinal position of the front end face of the central shaft 25B changes depending on the operating conditions of the ship, for example, the temperatures of the inner shaft 14 and the central shaft 25B, and the axial load. Therefore, it is preferable to measure the forward inner shaft position F1 and the reverse inner shaft position R1 while the ship is in operation, for example, when switching between forward and reverse. This makes it possible to make the ship's operation state substantially the same and reduce measurement errors due to the operation state.

[0045] (Measurement of second thrust gap C2) As described above, the outer shaft 12 and the outer intermediate shaft 17 are connected via the outer sleeve joint 16 so that no gap occurs in the axial direction. Therefore, while the ship is moving forward, the thrust of the front propeller 1 acts forward (to the right in the figure), and the outer shaft 12 is pressed forward in the axial direction (to the right in the figure), moving until the rear gap of the contra-rotating thrust bearing 40 and the front gap of the inner shaft thrust bearing 50 become zero. Similarly, when the ship is moving backward, the thrust of the front propeller 1 acts backward (to the left in the figure), so that the outer shaft 12 is pressed backward in the axial direction (to the left in the figure), and moves until the front gap of the contra-rotating thrust bearing 40 and the rear gap of the inner shaft thrust bearing 50 become zero.

[0046] During forward and reverse travel, both the first thrust gap C1 and the second thrust gap C2 change. Therefore, the difference in the front-rear direction between the forward movement outer shaft position F2 measured during forward movement and the reverse movement outer shaft position R2 measured during reverse movement corresponds to the sum of the first thrust gap C1 and the second thrust gap C2. Therefore, the second thrust gap C2 is the difference between the forward outer shaft position F2 and the reverse outer shaft position R2 (Δ2=F2-R2) minus the value (Δ1=F1-R1) that corresponds to the first thrust gap C1.

[0047] The outer shaft position sensor 64 is fixed to a fixed portion inside the hull and detects, for example, the end face of the outer intermediate shaft 17. In this case, the reference position (measurement origin) of the outer shaft position sensor 64 is set, for example, to the rear end face of the outer intermediate shaft 17. However, the longitudinal position of the rear end face of the outer intermediate shaft 17 changes depending on the operating state of the ship, for example, the temperatures of the outer shaft 12 and the outer intermediate shaft 17, and the axial load. Therefore, it is preferable to measure the forward outer shaft position F2 and the reverse outer shaft position R2 while the ship is in operation, for example, when switching between forward and reverse. It is also preferable to measure the forward inner shaft position F1 and the reverse inner shaft position R1 at the same time. This makes it possible to make the ship's navigation conditions substantially the same, thereby reducing measurement errors due to navigation conditions.

[0048] FIG. 4 is a schematic diagram showing detection data of the inner shaft position sensor 62 and the outer shaft position sensor 64. As shown in FIG. As shown in this figure, the detection data of the inner shaft position sensor 62 and the outer shaft position sensor 64 normally fluctuates at a period corresponding to the rotation speed due to the rotation of the outer shaft 12 and the inner shaft 14. This fluctuation is also caused by, for example, axial misalignment of the measuring parts and vibration of the hull 90. Therefore, it is preferable to use the average values ​​of the forward outer shaft position F2, reverse outer shaft position R2, forward inner shaft position F1, and reverse inner shaft position R1, taking into consideration the above fluctuation range.

[0049] Furthermore, as mentioned above, each measurement value varies depending on the operating state of the ship, so it is advisable to measure the outer shaft position F2 when moving forward, the outer shaft position R2 when moving backward, the inner shaft position F1 when moving forward, and the inner shaft position R1 when moving backward while the ship is operating in a manner that can be considered to be the same.

[0050] In addition, in order to understand and match the operating conditions of the ship, it is preferable to also measure and record the shaft rotation speed, rotation direction, shaft output (or shaft torque, shaft thrust), ship speed, steering position, casing vibration, etc.

[0051] According to the embodiment of the present invention described above, while the ship is traveling, the inner shaft position F1 during forward travel and the inner shaft position R1 during reverse travel are measured by the inner shaft position sensor 62. In addition, the thrust clearance calculation device 66 calculates the first thrust clearance C1 of the inner shaft thrust bearing 50 from the inner shaft position F1 during forward travel and the inner shaft position R1 during reverse travel. Therefore, the thrust clearance can be measured while the ship is operating, without having to open up the marine contra-rotating propeller device 100 for maintenance.

[0052] In addition, the following associated effects can be obtained: (1) Since the thrust clearance can be measured during operation, it is possible to determine whether or not maintenance is necessary before docking. (2) Measurements in a dry dock require axial movement using a hydraulic jack, which requires some skill in the work, but measurements can be automated during operation, so anyone can do the measurements. (3) Periodic open maintenance can be avoided, reducing system downtime and costs. (4) System automation will be possible to accommodate unmanned ships.

[0053] The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit and scope of the present invention. [Explanation of symbols]

[0054] C1 First thrust gap, C2 Second thrust gap, F1 Inner shaft position when moving forward, F2 Outer shaft position when moving forward, R1 Inner shaft position when reversing, R2 Outer shaft position when reversing, 1 front propeller, 2 rear propeller, 3 stern tube, 5 front bush, 6 rear bush, 7 bow side stern tube seal device, 8 aft side stern tube seal device, 12 outer shaft (outer propeller shaft), 13 boss, 13a annular recess, 14 inner shaft (inner propeller shaft), 15 boss, 16 outer shaft sleeve coupling, 17 outer intermediate shaft, 18A outer shaft transmission mechanism, 18B inner shaft transmission mechanism, 19 gear coupling, 20 contra-rotating gear device, 21 housing, 22 outer shaft input gear, 23 outer shaft intermediate gear, 24 outer shaft output gear, 25A hollow central shaft, 25B central shaft, 26 inner shaft sleeve joint, 27 inner shaft input gear, 28 inner shaft intermediate gear, 29 inner shaft output gear, 30 drive unit, 31 first drive unit, 31a output shaft, 32 second drive unit, 32a output shaft, 33a, 33b gear coupling, 35 front radial bearing, 36 rear radial bearing, 37 contra-rotating front seal device, 38 Contra-rotating rear seal device, 39 Propeller nut, 40 contra-rotating thrust bearing, 44 oil passage hole, 45 propeller cap, 46 retaining flange, 50 inner shaft thrust bearing, 52 self-aligning radial bearing, 53 Self-aligning thrust bearing, 54,55 Radial roller bearing, 56 Self-aligning radial bearing, 60 Thrust gap measuring device, 62 inner shaft position sensor, 64 outer shaft position sensor, 66 thrust gap calculation device, 90 Hull, 100 Marine contra-rotating propeller device

Claims

1. A thrust gap measurement device for a marine contra-rotating propeller system in which a front propeller and a rear propeller are arranged coaxially and rotate in opposite directions, The marine contra-rotating propeller device includes a hollow outer shaft having a rear end to which the front propeller is attached and supported rotatably around an axis thereof; an inner shaft having a rear end to which the rear propeller is attached and supported rotatably around the axis; A contra-rotating thrust bearing that transmits a thrust force acting on the front propeller to the inner shaft; a counter-rotating gear device that rotates the outer shaft and the inner shaft in opposite directions to each other, The contra-rotating gear device has an inner shaft thrust bearing that supports a thrust force of the inner shaft and maintains its axial position, The thrust gap measuring device is an inner shaft position sensor for measuring a forward movement position F1 and a reverse movement position R1 of the inner shaft in an axial direction of the inner shaft while the ship is traveling; an outer shaft position sensor for measuring an outer shaft position F2 during forward travel and an outer shaft position R2 during reverse travel in the axial direction of the outer shaft while the ship is in operation; a thrust gap calculation device that calculates a first thrust gap of the inner shaft thrust bearing and a second thrust gap of the contra-rotating thrust bearing.

2. 2. The thrust gap measuring device according to claim 1, wherein the inner shaft position sensor or the outer shaft position sensor is a non-contact distance sensor fixed to a fixed portion inside a hull.

3. Using the thrust gap measuring device according to claim 1, While the ship is traveling, the forward inner shaft position F1 and the reverse inner shaft position R1 are measured; A first thrust gap of the inner shaft thrust bearing is calculated from the forward movement inner shaft position F1 and the reverse movement inner shaft position R1. While the ship is traveling, the forward outer shaft position F2 and the reverse outer shaft position R2 are measured; a second thrust gap of the contra-rotating thrust bearing is calculated from the inner shaft position F1 during forward travel, the inner shaft position R1 during reverse travel, the outer shaft position F2 during forward travel, and the outer shaft position R2 during reverse travel.

4. A ship comprising the thrust gap measuring device according to claim 1.

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