Marine shaft sealing device, seal differential pressure control method, and counter-rotating propeller device

Abstract

This invention provides a means to arrange equipment at a height that does not exceed the upper deck, even in small vessels with limited engine room space, and to maintain appropriate seal differential pressure even in vessels with large draft changes. [Solution] The marine shaft seal device 100 comprises an air seal device 10, an air supply device 20, a drain recovery device 30, an oil supply device 40, and an oil recovery device 50. The oil recovery device has a hydraulic pressure adding pipe 54 that extends upward from the oil outlet 6d and adds hydraulic pressure equivalent to the pipe height to the oil bath space Rb, an intermediate pipe 55 connected to the upper end of the hydraulic pressure adding pipe, and a return pipe 56 connected to the intermediate pipe, with its upper end open to the atmosphere and its lower end connected to the oil tank. The upper end height of the hydraulic pressure adding pipe is set to a height lower than the maximum draft + 2m. Furthermore, it has a seal differential pressure control device 60 provided in the intermediate pipe 55. The seal differential pressure control device 60 works in conjunction with the draft pressure Pd and adds a seal pressure Ps greater than the draft pressure to the oil outlet.

Description

Technical Field

[0001] The present invention relates to a marine shaft sealing device that liquid-tightly seals between a marine propulsion shaft and a stern, a seal differential pressure control method, and a contra-rotating propeller apparatus.

Background Art

[0002] A shaft sealing device for a marine propulsion shaft (hereinafter referred to as a marine shaft sealing device) needs to prevent both (1) seawater from entering the ship and (2) oil from leaking out of the ship. Therefore, particularly in marine shaft sealing devices for large vessels, a shaft sealing device is adopted in which three or more sealing members are provided in the axial direction of the marine propulsion shaft, and an air seal space, a seal oil space, and an oil bath space are sequentially formed from the hull exterior side between the hull exterior and the hull interior.

[0003] Seal air is supplied to the air seal space, and lubricating oil is supplied to the oil bath space. Furthermore, by appropriately maintaining the pressure of the oil bath space at a pressure higher than that of the air seal space, seal air and lubricating oil do not move between the air seal space, the seal oil space, and the oil bath space, so that both seawater intrusion into the ship and oil leakage to the outside of the ship can be prevented.

[0004] The marine shaft sealing device described above is disclosed in, for example, Patent Document 1.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] Because marine propulsion shafts are located near the bottom of the hull, they are constantly subjected to draft pressure, which corresponds to the difference in height between the water surface and the bottom. Therefore, in order to prevent seawater from entering the ship, it is necessary to control the pressure in the air seal space to a pressure higher than the draft pressure, and to further control the pressure in the seal oil space and oil bath space to an even higher pressure to prevent air from mixing with the lubricating oil. Hereinafter, the pressure in the air seal space will be referred to as "seal air pressure," the pressure in the oil bath space as "lubricating oil pressure," and the difference between the seal air pressure and the pressure in the adjacent space as "seal differential pressure."

[0007] Two known methods for controlling seal differential pressure are the closed-circuit method (sealed method) and the riser piping method (open method).

[0008] In closed-circuit seal differential pressure control, the lubrication system is enclosed in a closed circuit, pressurizing the entire system. By controlling this pressurized pressure, an appropriate seal differential pressure is ensured, thereby achieving both good sealing performance and long seal ring life. Furthermore, to create a closed, pressurized circuit, the lubricating oil tank is a separate, standalone tank (pressure tank).

[0009] However, closed-circuit seal differential pressure control has the following problems: (1) While the stern pipe oil system is a pressurized closed circuit, the pressure of the lubrication oil system for the sealing device on the engine room side is lower than that of the stern pipe oil system. Therefore, it is necessary to have a circulation system, including a self-circulating system, separate from the stern pipe oil system which has a dedicated tank (storage tank). (2) When the total oil volume of the stern pipe oil system is large, changes in oil volume occur due to expansion and contraction caused by temperature changes, and it is necessary to enlarge the tanks and give them a buffer function so that they can absorb these changes. However, this is difficult to do with stationary tanks because they have a smaller capacity than tanks attached to the hull. (3) In the case of large ships, the heat dissipation performance is insufficient with a self-circulating system, so in addition to a dedicated tank, a dedicated lubricating oil pump and lubricating oil cooler must be installed for the lubrication and cooling of the sealing device on the engine room side. (4) Because the tank is pressurized, it is not possible to use a tank that is integrated into the hull structure (a tank attached to the hull), and it is necessary to install a separate tank (a tank placed on the hull), which makes it difficult to arrange equipment on small ships with limited engine room space.

[0010] On the other hand, the seal differential pressure control using the riser piping method utilizes the hydrostatic head pressure of the piping that returns from the stern tube to the lubricating oil tank as a riser piping, in order to maintain a constant lubricating hydraulic pressure at the seal. In a riser piping system for seal differential pressure control, the seal air pressure changes small in ships with minimal draft pressure fluctuations, allowing for appropriate seal differential pressure even with constant lubrication hydraulic pressure. Therefore, it is not necessary to control and pressurize the entire system, and there is the advantage of being able to use a tank attached to the hull.

[0011] However, the seal differential pressure control using the riser piping method had the following problems. (1) In order to ensure an appropriate seal differential pressure, the riser piping needs to be at a height of approximately +6m above the maximum draft. In the case of small vessels, this would have to exceed the height of the engine room, the upper deck, and even the top of the funnel, making placement extremely difficult. (2) In reality, the draft pressure changes, and the seal air pressure changes accordingly. With a riser piping system, the lubrication hydraulic pressure remains constant, so the seal differential pressure changes, and in particular, it is not possible to maintain an appropriate seal differential pressure on ships with large draft changes.

[0012] This invention was devised to solve the problems described above. In other words, the object of this invention is to provide a means that allows equipment to be arranged at a height that does not exceed the upper deck, even in small ships with limited engine room space, and that can maintain an appropriate seal differential pressure even in ships with large draft changes. [Means for solving the problem]

[0013] According to the present invention, an air seal device has three or more sealing members in the axial direction between the marine propulsion shaft and the stern, and sequentially forms an air seal space, a seal oil space, and an oil bath space from the outside of the hull, an air supply device configured to supply seal air to the air seal space, a drain recovery device configured to recover drain from the air seal space, an oil supply device configured to supply oil to the seal oil space and the oil bath space, and an oil recovery device configured to recover oil from the oil bath space, wherein the oil supply device includes an oil tank that stores oil therein, an oil pump that pressure-feeds the oil, and an oil pressure feed line that supplies oil from the oil tank to the oil bath space and the seal oil space, the oil recovery device includes a hydraulic pressure applying pipe that extends upward from an oil discharge port provided in a stern tube and applies a hydraulic pressure corresponding to the pipe height to the oil bath space, an intermediate pipe connected to an upper end of the hydraulic pressure applying pipe, and a return pipe connected to the intermediate pipe, having an upper end open to the atmosphere and a lower end connected to the oil tank, the height of the upper end of the hydraulic pressure applying pipe is set to a height lower than the maximum draft + 2 m, and further a seal differential pressure control device provided in the intermediate pipe, interlocked with the draft pressure, and applying a seal pressure greater than the draft pressure to the oil discharge port. A marine shaft sealing device is provided.

[0014] Further, according to the present invention, An air seal device having three or more sealing members in the axial direction between the marine propulsion shaft and the stern, which sequentially forms an air seal space, a seal oil space, and an oil bath space from the outside of the hull, An air supply device that supplies sealing air to the aforementioned air seal space, A drain recovery device for recovering drain from the aforementioned air seal space, An oil supply device that supplies oil to the seal oil space and the oil bath space, The system includes an oil recovery device for recovering oil from the oil bath space, The oil supply device comprises an oil tank that holds oil internally, an oil pump that pumps oil, and an oil pumping line that supplies oil from the oil tank to the oil bath space and the seal oil space. The aforementioned oil recovery device is Extending upward from the oil discharge port provided in the stern tube The aforementioned a hydraulic pressure applying pipe that applies a hydraulic pressure corresponding to the pipe height to the oil bath space, an intermediate pipe connected to the upper end of the hydraulic pressure applying pipe, and a return pipe connected to the intermediate pipe, with its upper end open to the atmosphere and its lower end The aforementioned connected to the oil tank, The height of the upper end of the hydraulic pressure applying pipe is set to a height lower than the maximum draft + 2 m, further provided in the intermediate pipe, interlocking with the draft pressure The draft pressure greater than sealing pressure a seal differential pressure control device for applying to the oil discharge port, The seal differential pressure control device has a pressure regulating valve provided in the intermediate pipe, transmits the oil pressure in the vicinity of the oil discharge port to the primary pressure detection chamber of the pressure regulating valve, and The aforementioned interlocking with the draft pressure The sealing air pressure was adjusted using an air relay. transmits a bias pressure to the atmospheric pressure detection chamber of the pressure regulating valve. A seal differential pressure control method is provided.

[0015] Further, according to the present invention, a contra-rotating propeller apparatus including the above marine shaft sealing device is provided. [Effects of the Invention]

[0016] According to the above configuration of the present invention, by setting the height of the upper end of the hydraulic pressure applying pipe to a height lower than the maximum draft + 2 m, a hydraulic pressure corresponding to the pipe height (for example, a water head pressure of +1 m or more and +3 m or less) can be applied to the oil bath space communicating with the oil discharge port.

[0017] In addition, since the seal differential pressure control device applies a seal pressure greater than the draft pressure in conjunction with the draft pressure to the oil discharge port, the lubricating oil pressure in the oil bath space and the seal oil space can be maintained at a seal pressure (≈ draft pressure + β) that is always higher than the seal air pressure (= draft pressure + α), and an appropriate seal differential pressure can always be secured.

[0018] Therefore, even for small vessels with small engine room space, the equipment can be arranged at a height that does not exceed the upper deck or the like, and an appropriate seal differential pressure can be maintained in vessels with large draft variations. [Brief Description of the Drawings]

[0019] [Figure 1] It is a diagram of a first embodiment of the marine shaft sealing device according to the present invention. [Figure 2] This is an explanatory diagram of the air seal device according to the first embodiment. [Figure 3] This is a pressure balance diagram within the air seal device. [Figure 4] This is an explanatory diagram of a seal differential pressure control device. [Figure 5] Figure 1 is an enlarged view of the area surrounding the bow-side stern tube sealing device. [Figure 6] This is a diagram of a second embodiment of a marine shaft sealing device according to the present invention. [Figure 7] This is an explanatory diagram of the air seal device according to the second embodiment. [Figure 8] This is a pressure balance diagram of the air seal device according to the second embodiment. [Modes for carrying out the invention]

[0020] Embodiments of the present invention will be described below with reference to the drawings. Common parts in each figure are denoted by the same reference numerals, and redundant explanations are omitted.

[0021] (First Embodiment) Figure 1 is a diagram of a first embodiment of the marine shaft sealing device 100 according to the present invention. In this figure, the marine shaft seal device 100 is a device that provides a liquid-tight seal between the marine propulsion shaft 1 and the stern 4. The marine propulsion shaft 1 has a propeller 3 attached to its rear end (left end in the diagram) and is driven to rotate around the axis Z by a drive mechanism (not shown). The stern tube 2 is a hollow cylindrical member integrally provided through the stern 4, and the marine propulsion shaft 1 is rotatably supported by stern tube bearings 5a and 5b fixed inside it.

[0022] In Figure 1, the marine shaft sealing device 100 of the present invention comprises an air seal device 10, an air supply device 20, a drain recovery device 30, an oil supply device 40, and an oil recovery device 50.

[0023] (Air seal device 10) Figure 2 is an explanatory diagram of the air seal device 10 of the first embodiment. In this figure, Figure 2(A) is an enlarged view of the surrounding area of ​​the air seal device 10 of Figure 1, and Figure 2(B) is a schematic diagram thereof.

[0024] The air seal device 10 has three or more (three in this example) sealing members 11 in the axial direction between the marine propulsion shaft 1 and the stern tube 2, and sequentially forms an air seal space Ra, a sealing oil space Ro, and an oil bath space Rb between the outside and inside of the hull, starting from the outside of the hull.

[0025] In this example, the air seal device 10 is the stern tube seal device 10A on the stern side. Each of the sealing members 11 is a sealing ring, and hereafter they will be referred to as the #1 sealing ring, the #2 sealing ring, and the #3 sealing ring, in order from the outside of the hull (stern side). In this example, an air seal space Ra is formed between the #1 sealing ring and the #2 sealing ring, an AFT sealing oil space (hereinafter referred to as the aft sealing oil space Ro) is formed between the #2 sealing ring and the #3 sealing ring, and an oil bath space Rb is formed between the #3 sealing ring and the #4 sealing ring.

[0026] (Air supply device 20) The air supply device 20 supplies air (hereinafter referred to as seal air A) to the air seal space Ra (between the #1 seal ring and the #2 seal ring). In Figures 1 and 2, the air supply device 20 includes an air control unit 22, air piping 23, and a flow path 24.

[0027] The air control unit 22 generates seal air A and controls the pressure. The air piping 23 supplies sealing air A to the air supply port 6a of the stern tube 2. In this example, the air supply port 6a is located near the upper end of the stern tube 2. The flow path 24, indicated by symbols a1-a2 in Figure 2, is provided in the stern tube 2 and the seal casing (not shown), and connects the seal air A from the air supply port 6a to the air seal space Ra.

[0028] In Figure 1, the air control unit 22 includes a regulator 25, a flow controller 26, and an air relay 28.

[0029] Regulator 25 outputs air at a constant pressure. The flow controller 26 controls the seal air pressure Pa to be higher than the draft pressure Pd by flowing a constant flow rate of seal air A. In other words, even when the draft pressure Pd fluctuates, the flow controller 26 controls the pressure in the air seal space Ra (seal air pressure Pa) to be higher than the draft pressure Pd by flowing a constant flow rate of seal air A without stopping it.

[0030] The waterline pressure Pd varies depending on the draft conditions, and is, for example, between 0.02 and 0.04 MPa. The "pressure higher than the draft pressure Pd" indicated by the flow controller 26 is the pressure corresponding to the draft pressure Pd (draft pressure Pd + pressure pushing up the seal ring), for example, draft pressure Pd + α. α is, for example, the hydrostatic pressure at 1.5 m, which is 0.015 MPa in the example described later. In this example, α > 0, but there are also cases where α ≤ 0.

[0031] The air relay 28 outputs a control air Ac with a bias pressure Pb, which is the seal air pressure Pa adjusted. Control air Ac is supplied via the bias pressure line 68 to the atmospheric pressure sensing chamber 62c (see Figure 4) of the pressure regulating valve 62, which will be described later. A relief valve (not shown) is preferably provided in the bias pressure line 68.

[0032] In Figure 2, the seal air A supplied to the air seal space Ra between the #1 seal ring and the #2 seal ring pushes up the #1 seal ring and flows into the seawater. A portion of it also returns to the engine room along with the shield drain (drain D).

[0033] With the configuration of the air supply device 20 described above, the air control unit 22 can supply seal air A to the air seal space Ra via the air piping 23 and flow path 24, and the pressure in the air seal space Ra (seal air pressure Pa) can always be controlled to be higher than the draft pressure Pd.

[0034] (Drain recovery device 30) The drain recovery device 30 recovers drain D together with drain air A1 from the lower part of the air seal space Ra.

[0035] In this invention, the pressure in the rear seal oil space Ro is controlled to be higher than the pressure in the air seal space Ra so that the seal air A does not mix with the lubricating oil (hereinafter referred to as oil O). Therefore, there is a possibility that oil O may mix with the seal air A via the #2 seal ring. Drain air A1 refers to seal air A mixed with oil O. Drain D refers to oil O that has entered the air seal space Ra. The physical properties of drain air A1 and drain D are substantially the same as those of seal air A and oil O, respectively, but they differ in that they each contain impurities.

[0036] In Figures 1 and 2, the drain recovery device 30 in this example includes a flow path 32 that connects the drain D from the lower part of the air seal space Ra to the drain outlet 6b, a drain pipe 33 that discharges the drain D from the drain outlet 6b, and a drain recovery unit 35 that recovers and stores the drain D. In this example, the drain outlet 6b is located near the lower end of the stern pipe 2. The flow path 32 is shown in Figure 2 by the symbols a3-a4.

[0037] With the configuration of the drain recovery device 30 described above, the drain D is carried by gravity along with the flow of drain air A1 from the bottom of the air seal space Ra through the flow path 32 and the drain pipe 33 to the drain recovery unit 35, and the drain D can be recovered in the drain recovery unit 35.

[0038] (Oil supply device 40) The oil supply device 40 supplies oil O to the rear seal oil space Ro and the oil bath space Rb of the air seal device 10. In Figure 1, the oil supply device 40 includes an oil tank 42 that holds oil O internally, an oil pump 44 that pumps the oil O, and an oil pumping line 46 that supplies oil O from the oil tank 42 to the air seal device 10.

[0039] In this example, the oil tank 42 is a hull-mounted tank and is open to the atmosphere without pressurization. In this example, two oil pumps 44 are provided, each with a check valve 44a before and after it, facilitating maintenance of the oil pumps 44.

[0040] The oil pumping line 46 includes a suction pipe 46a from the oil tank 42 to the oil pump 44, a first pumping pipe 46b from the oil pump 44 to the oil supply port 6c provided in the stern pipe 2, and a flow path 47 that supplies oil O from the oil supply port 6c to the oil bath space Rb. The oil bath space Rb from the oil supply port 6c is between the seal rings #3 and #4. The flow path 47 is shown in Figure 2 by the labels b1 and b2.

[0041] With the configuration of the oil supply device 40 described above, oil O can be pumped from the oil tank 42 to the oil bath space Rb of the air seal device 10 via the oil pressure supply line 46.

[0042] (Pressure balance within the air seal device) Figure 3 is a pressure balance diagram within the air seal device.

[0043] In this example, the oil supply device 40 has a flow path (not shown) that supplies oil O to the rear seal oil space Ro between the seal rings #2 and #3.

[0044] The oil O that flows into the rear seal oil space Ro between seal rings #2 and #3 pushes up seal ring #3 and flows into the passage 47. Also, when the supply of oil O to the rear seal oil space Ro between seal rings #2 and #3 is stopped, seal ring #3 comes into contact with the seal liner (not shown) and functions as a seal.

[0045] In Figure 3, the draft pressure Pd fluctuates with changes in draft, for example, within a range of 0.02 MPa to 0.04 MPa. This range corresponds to a hydrostatic pressure of approximately 2 m to 4 m. The pressure in the air seal space Ra between seal rings #1 and #2 is automatically controlled by the flow controller 26 described above to the draft pressure Pd + α (α > 0). α is, for example, the hydrostatic head pressure at 1.5 m, which in this example is 0.015 MPa. The pressure in the rear seal oil space Ro between seal rings #2 and #3 is higher than that in the air seal space Ra, which in this example is the pressure in the air seal space Ra + 0.04 MPa (= draft pressure Pd + 0.055 MPa).

[0046] The oil O between seal rings #2 and #3 pushes up seal ring #3 and flows into the space between seal rings #3 and #4 (b2 in Figure 2). Therefore, in this example, the pressure between seal rings #3 and #4 is the pressure between seal rings #2 and #3 - 0.015 MPa (= draft pressure Pd + 0.04 MPa).

[0047] Due to the pressure balance described above, even when the draft pressure Pd fluctuates, the pressure in the air seal space Ra is always kept higher than the draft pressure Pd, and the pressure in the aft seal oil space Ro is appropriately kept higher than the air seal space Ra. As a result, the seal air A and lubricating oil (oil O) do not move between the air seal space Ra and the aft seal oil space Ro, preventing both seawater intrusion into the vessel and oil leakage overboard.

[0048] (Oil recovery device 50) The oil recovery device 50 recovers oil O from the oil bath space Rb. In Figures 1 and 2, the oil recovery device 50 in this example has a flow path 52 indicated by reference numerals b3 and b4, a hydraulic pressure supply pipe 54, an intermediate pipe 55, and a return pipe 56. The hydraulic pressure supply piping 54 will hereafter be referred to as the riser piping 54. Note that the hydraulic pressure supply piping 54 may also be a dropper piping. In Figure 2, the flow path 52 connects the oil O from the oil bath space Rb to the oil outlet 6d located at the top of the stern pipe 2.

[0049] In Figure 1, the riser pipe 54 extends upward from the oil outlet 6d provided in the stern pipe 2, and applies a hydraulic pressure to the oil outlet 6d that corresponds to the height of the pipe. This hydraulic pressure is the hydrostatic pressure of the oil O flowing inside the riser pipe 54. The intermediate pipe 55 is preferably connected horizontally to the upper end of the riser pipe 54. The return pipe 56 is connected to the downstream side of the intermediate pipe 55, with its upper end 56a open to the atmosphere and its lower end connected to the oil tank 42.

[0050] The oil O supplied from the oil pump 44 is delivered to the stern space of the stern tube bearing 5a via an internal conduit in the oil bath, flows through the stern tube bearings 5a and 5b in that order, and returns to the oil tank 42 via the riser pipe 54, intermediate pipe 55, and return pipe 56.

[0051] The upper end height of the riser pipe 54 is set to a height lower than the maximum draft + 2m. This configuration allows for the application of hydraulic pressure (for example, a hydrostatic head pressure of +1m or more and +3m or less) equivalent to the pipe height of the rising pipe 54 to the oil bath space Rb that communicates with the oil outlet 6d.

[0052] The rising pipe 54 preferably extends vertically upward or diagonally upward from the oil outlet 6d. The intermediate pipe 55 is preferably a horizontal pipe. Furthermore, the intermediate pipe 55 joins the return pipe 56 at a confluence point 53 below the upper end 56a.

[0053] In Figure 1, the oil recovery device 50 further includes a seal differential pressure control device 60 installed in the intermediate piping 55. The seal differential pressure control device 60 has the function of being linked to the water pressure Pd and applying a seal pressure Ps greater than the water pressure to the oil outlet 6d.

[0054] Figure 4 is an explanatory diagram of the seal differential pressure control device 60. In this figure, Figure 4(A) is an enlarged view of the surrounding area of ​​the seal differential pressure control device 60 shown in Figure 1, and Figure 4(B) is a schematic diagram of the pressure regulating valve 62.

[0055] In Figures 1 and 4, the seal differential pressure control device 60 includes a pressure regulating valve 62 provided in the intermediate piping 55, and a pilot line 67 that transmits the oil pressure near the oil outlet 6d to the primary pressure detection chamber 62b of the pressure regulating valve 62 via the primary pressure detection port 60a. The pressure regulating valve 62 should be installed at a height higher than the oil outlet 6d, preferably at the same height as the intermediate piping 55.

[0056] The pressure regulating valve 62 is a direct-acting primary pressure regulating valve. In Figure 4(B), the pressure regulating valve 62 has a primary pressure detection chamber 62b for detecting pilot pressure and an atmospheric pressure detection chamber 62c for detecting atmospheric pressure. In this diagram, the direct-acting piston 62a adjusts the flow area of ​​the intermediate pipe 55. The primary pressure detection chamber 62b surrounds the lower part (valve seat side) of the piston 62a. The atmospheric pressure sensing chamber 62c surrounds the upper part (rear side) of the piston 62a. Furthermore, the primary pressure detection chamber 62b is provided with a primary pressure detection port 60a, and the atmospheric pressure detection chamber 62c is provided with a back pressure detection port 60b.

[0057] As shown in Figure 4(B), the atmospheric pressure detection chamber 62c of the pressure regulating valve 62 may be pre-provided with an access path (back pressure detection port 60b) as a drain recovery line or the like. In that case, as will be described later in the present invention, a bias pressure Pb is applied to the back pressure detection port 60b. Furthermore, an atmospheric pressure detection chamber 62c may be provided to surround the entire pressure regulating valve 62.

[0058] In the seal differential pressure control method of the present invention, the oil pressure near the oil outlet 6d is transmitted to the primary pressure detection chamber 62b of the pressure regulating valve 62 using a pilot line 67.

[0059] In Figure 4(B), the oil O flowing in from the pilot line 67 reaches the bottom of the piston 62a and acts as an upward force. When the pressure in the pilot line 67 rises and exceeds the set pressure, it overcomes downward forces such as spring loads, pushing up the piston 62a and opening the valve, preventing the primary side pressure from rising. Conversely, when the pressure in the pilot line 67 falls below the set pressure, the downward force acting on the piston 62a becomes greater than the upward force, pushing down the piston 62a and adjusting the valve opening to control the primary side pressure to a constant level. This configuration allows the oil pressure near the oil outlet 6d to be controlled to the set pressure of the pressure regulating valve 62 when the atmospheric pressure detection chamber 62c is open to the atmosphere. The set pressure of the pressure regulating valve 62 is, for example, 0.05 MPa.

[0060] In Figure 1, the seal differential pressure control device 60 further has a bias pressure line 68. The bias pressure line 68 supplies the control air Ac of the bias pressure Pb or seal air pressure Pa output from the air relay 28 to the atmospheric pressure detection chamber 62c via the back pressure detection port 60b. In the seal differential pressure control method of the present invention, a bias pressure line 68 is used to transmit the bias pressure Pb or seal air pressure Pa, which is linked to the draft pressure Pd, to the atmospheric pressure detection chamber 62c of the pressure regulating valve 62.

[0061] With the configuration described above, in Figure 1, the circuit from the tank outlet to the check valve 63 is closed, and the oil tank 42 is open to the atmosphere. The pressure regulating valve 62 controls the differential pressure between the pilot pressure in the pilot line 67 and atmospheric pressure so that it becomes a set pressure (for example, 0.05 MPa). By setting the bias pressure Pb of this atmospheric pressure line using the bias pressure line 68, the set pressure can be controlled with an offset value.

[0062] In other words, with the above configuration, the oil pressure near the oil outlet 6d can be controlled to the set pressure of the pressure regulating valve 62 plus the bias pressure Pb. The bias pressure Pb controlled by the air relay 28 can be remotely and arbitrarily adjusted.

[0063] For example, if the set pressure of the pressure regulating valve 62 is 0.05 MPa and the bias pressure Pb from the air relay 28 is Pb = water pressure Pd - γ, then the oil pressure near the oil outlet 6d will be water pressure Pd - γ + 0.05 MPa.

[0064] In Figure 1, the seal differential pressure control device 60 has a check valve 63 located downstream of the pressure regulating valve 62 in the intermediate piping 55. The check valve 63 prevents backflow of oil O from flowing from the pressure regulating valve 62 to the confluence point 53. With this configuration, when the bias pressure Pb is the water pressure Pd-γ, the oil pressure near the oil outlet 6d will be the water pressure Pd-γ + 0.06 MPa.

[0065] Therefore, for example, in the case of the pressure balance shown in Figure 3, the oil pressure near the oil outlet 6d is the draft pressure Pd + 0.04 MPa, and the following equation (1) holds true. Draft pressure Pd-γ+0.06MPa=Draft pressure Pd+0.04MPa...(1) From equation (1), we get γ = 0.02 MPa...(2). Therefore, for example, if α is 0.015 MPa, then from equation (2), γ is 0.02 MPa. 0.02 MPa corresponds to a hydrostatic pressure of approximately 2 m.

[0066] In other words, if the seal air pressure Pa is the water pressure Pd + α (α > 0), it is best to set the bias pressure Pb from the air relay 28 to a value slightly lower than the water pressure Pd (for example, -0.02 MPa) so that the seal pressure Ps becomes the water pressure Pd + β (β > α). Furthermore, the bias pressure Pb may be set to a value higher than, for example, the draft pressure Pd. With this configuration, the lubricating oil pressure Po in the oil bath space Rb is always maintained at a hydrostatic head pressure higher than the seal air pressure Pa, even when the draft pressure Pd fluctuates, thus ensuring that an appropriate seal differential pressure is always maintained.

[0067] In Figures 1 and 4(A), the seal differential pressure control device 60 further includes a bypass line 58 that bypasses the pressure regulating valve 62 and the check valve 63, a needle valve 64 provided on the bypass line 58, and a switching valve 65 provided at the confluence point of the downstream end of the bypass line 58 and the intermediate piping 55. In this example, the switching valve 65 is a three-way valve 65. Furthermore, an on-off valve 61 is provided upstream of the pressure regulating valve 62. The needle valve 64 is located in parallel with the pressure regulating valve 62, and a three-way valve 65 allows switching between the pressure regulating valve 62 and the needle valve 64.

[0068] This configuration allows maintenance of the pressure regulating valve 62 or check valve 63 to be performed while the seal differential pressure control device 60 is in use by switching the three-way valve 65, fully closing the on-off valve 61, and allowing oil to flow from the upper end of the riser pipe 54 to the confluence point 53 via the bypass line 58. Furthermore, the needle valve 64 can be adjusted so that the pressure loss generated in the needle valve 64 matches the pressure loss of the pressure regulating valve 62 and the check valve 63.

[0069] The flow from the outlet of the check valve 63 of the oil O to the oil tank 42 is due to gravity, and since the upper end 56a is open to the atmosphere, the inside of the return pipe 56 is also open to the atmosphere.

[0070] Furthermore, if the draft pressure Pd actually changes, the lubricating oil pressure Po may hunt due to the characteristics of the pressure regulating valve 62, etc. To prevent this, it is advisable to provide the following mechanism shown in Figure 4(A). (1) An auxiliary air tank 69 is provided in the middle of the bias pressure line 68. (2) Orifices 69a are provided before and after the auxiliary air tank 69. (3) The auxiliary air tank 69 is provided with a relief valve 69b. (4) The auxiliary air tank 69 is provided with a drain outlet 69c. The drain outlet 69c is also provided with an on / off valve 69d. (5) A drain detection sensor (not shown, such as a level switch) is provided in the auxiliary air tank 69.

[0071] This configuration allows for a gradual change in the bias pressure Pb applied to the pressure regulating valve 62 when the bias pressure Pb in the bias pressure line 68 changes, thereby suppressing hunting of the lubricating oil pressure Po. Furthermore, even if condensate is generated from the pressure regulating valve 62 due to aging, it is possible to prevent the condensate from flowing back to the air relay 28 and causing malfunction.

[0072] In Figure 1, the marine shaft sealing device 100 of the present invention further comprises a bow-side stern tube sealing device 14. Figure 5 is an enlarged view of the area surrounding the bow-side stern tube sealing device 14 shown in Figure 1.

[0073] In Figure 5, the bow-side stern tube sealing device 14 has multiple (two in this example) sealing members 11 in the axial direction, with an FWD seal oil space (hereinafter referred to as the forward seal oil space Ro1) formed between them. Each of the sealing members 11 is a seal ring, and hereafter they will be referred to as the #4 seal ring, the #5 seal ring, and so on, starting from the stern side.

[0074] (Oil supply device 70) In Figure 5, the marine shaft seal device 100 further includes an oil supply device 70. The oil dispensing device 70 is a device that branches the stern tube lubricating oil Ob supplied to the oil supply port 6c and supplies it as bow-side stern tube seal oil Oc to the bow-side stern tube seal oil supply port 6e.

[0075] In this example, the oil supply device 70 has a check valve 72 and an orifice 74 installed in series with the external piping 77. With this configuration, the check valve 72 can prevent backflow of the bow-side stern tube seal oil Oc, and the orifice 74 can adjust the flow rate of the bow-side stern tube seal oil Oc.

[0076] Furthermore, a riser pipe 54b is provided in the lubricating oil outlet line of the bow-side stern tube sealing device 14. The height of the riser pipe 54b should preferably be 1.5m. Furthermore, the outlet of the riser pipe 54b is connected to the return pipe 56 at the junction 53, similar to the riser pipe 54. The upper end 56a of the return pipe 56 is open to the atmosphere, and its lower end is connected to the oil tank 42. This configuration is the same as that of the riser pipe 54. The upper end height of the riser pipe 54b should preferably be approximately 2m or less from the axis Z. Furthermore, the seal differential pressure control device 60 described above is not required for the lubricating oil outlet line of the bow-side stern tube seal device 14.

[0077] Regarding the bow seal (bow-stern tube sealing device 14), in order to ensure the durability of the seal rings, the pressure between seal rings #4 and #5 can only be raised to, for example, a 2m head pressure. Therefore, in conventional air seal systems, the pressure in the stern tube lubrication system, including the lubrication oil tank, is higher than the pressure between seal rings #4 and #5, making it impossible to return the lubrication oil that has leaked out between seal rings #4 and #5 to the system. For this reason, it was necessary to have an independent circulation system for the bow-side stern tube seal device 14 (a dedicated storage tank in addition to a self-circulating circulation mechanism or a dedicated pump-cooler).

[0078] In this invention, with the above-described configuration, the oil tank 42 is at atmospheric pressure and is lower than the pressure between seal rings #4 and #5, thus eliminating the need for an independent circulation system for the bow-side stern tube sealing device 14.

[0079] (Second Embodiment) Figure 6 is a diagram of a second embodiment of the marine shaft sealing device 100 according to the present invention. In this figure, the marine shaft seal device 100 is a device that provides a liquid-tight seal between the marine propeller shaft 1 and the stern 4 of the contra-rotating propeller system. The marine propulsion shaft 1 consists of an outer propeller shaft 1A and an inner propeller shaft 1B, with a forward propeller 3A and a rear propeller 3B attached to their respective rear ends (left end in the diagram), and are rotated in opposite directions around the axis Z by a reversing device 80. The outer propeller shaft 1A is rotatably supported about its axis Z by stern tube bearings 5a and 5b, which are fixed inside the stern tube 2. Furthermore, the inner propeller shaft 1B is supported so as to be rotatable about the axis Z by a double counter-rotating bearing 82 located inside the front propeller 3A.

[0080] (Air seal device 10) Figure 7 is an explanatory diagram of the air seal device 10 of the second embodiment. In this figure, Figure 7(A) is an enlarged view of the surrounding area of ​​the air seal device 10 of Figure 6, and Figure 7(B) is a schematic diagram thereof.

[0081] In this example, the air seal device 10 includes a stern side stern tube seal device 10A provided between the outer propeller shaft 1A and the stern tube 2, and a contra-rotating seal device 10B provided between the forward propeller 3A and the aft propeller 3B. The stern tube sealing device 10A forms an air seal space Ra, a rear seal oil space Ro, and an air seal space Ra (for drain) in that order from the outside of the hull. Furthermore, the dual counter-rotating seal device 10B, similar to the first embodiment, sequentially forms an air seal space Ra and a rear seal oil space Ro from the outside of the hull.

[0082] Each of the sealing members 11 is a sealing ring, and they are referred to as #1 sealing ring, #2 sealing ring, #3 sealing ring, and #4 sealing ring in order from the stern side of the stern tube sealing device 10A. Similarly, they are referred to as #1 sealing ring, #2 sealing ring, and #3 sealing ring in order from the stern side of the double counter-rotating sealing device 10B. In this example, an air seal space Ra is formed between the #1 seal ring and the #2 seal ring, and a rear seal oil space Ro(10B) or rear seal oil space Ro(10A) is formed between the #2 seal ring and the #3 seal ring.

[0083] In this example, a front seal oil space Ro1 is also formed between seal rings #5 and #6. In this example, the oil supply device 40 also has a flow path (not shown) that supplies oil O to the rear seal oil space Ro between the #2 and #3 seal rings of the double reversing seal device 10B. Furthermore, this flow path is not pumped but self-circulating, and is connected to the CR#3 / #4 chambers at two points.

[0084] (Air supply device 20) As shown in Figure 7, flow paths 24A and 24B are provided, denoted by symbols a1, a2, and a3. The air supply device 20 supplies sealing air A to the air seal space Ra of the stern tube sealing device 10A and the double counter-rotating sealing device 10B. The other components of the air supply device 20 are the same as those in the first embodiment.

[0085] The air supply device 20 supplies sealing air A to the air seal space Ra (between the seal rings #1 and #2). The seal air A supplied to the air seal space Ra between seal rings #1 and #2 pushes up seal ring #1 and flows into the seawater. A portion of it also returns to the engine room along with the shield drains (drains D1 and D2).

[0086] With the configuration of the air supply device 20 described above, sealing air A is supplied to the air seal space Ra of the stern tube sealing device 10A and the double counter-rotating sealing device 10B via the flow paths 24A and 24B, and the sealing air pressure Pa can always be controlled to be higher than the draft pressure Pd.

[0087] (Drain recovery device 30) In Figure 6, the drain recovery device 30 includes a stern tube drain recovery device 30A and a double-rotating drain recovery device 30B. The stern tube drain recovery device 30A recovers the drain D1 from the stern side stern tube seal device 10A via the flow path 32A shown by reference numerals a4-a5 in Figure 7. The dual-reverse drain recovery device 30B recovers the drain D2 from the dual-reverse drain recovery device 30B via the flow path 32B shown by reference numerals a6-a7 in Figure 7. The other components of the drain recovery device 30 are the same as those in the first embodiment.

[0088] With the configuration of the drain recovery device 30 described above, drains D1 and D2 are carried out from the bottom of the air seal space Ra through the flow paths 32A and 32B by the flow of drain air A1 and their own gravity, and drains D1 and D2 can be collected separately in the drain recovery units 35A and 35B.

[0089] (Oil supply device 40) In Figure 6, the oil supply device 40 includes an oil tank 42, an oil pump 44, and an oil pumping line 46. The oil tank 42 and the oil pump 44 are the same as in the first embodiment.

[0090] In Figures 6 and 7, the oil pumping line 46 includes a suction pipe 46a, a first pumping pipe 46b, a second pumping pipe 46c, a flow path 47, and a flow path 48. The suction pipe 46a, the first pumping pipe 46b, and the flow path 47 are the same as in the first embodiment.

[0091] In Figure 6, the second pressure pipe 46c supplies oil O to an oil supply port 7a located on the bow side axis of the inner propeller shaft 1B via a rotary coupling (not shown). In Figure 7, the flow path 48 enters the gap between the outer propeller shaft 1A and the inner propeller shaft 1B from the hollow flow path of the inner propeller shaft 1B which is in communication with the oil supply port 7a, and flows along the path indicated by symbols c1-c2-c3-c4-c5. Furthermore, it is preferable to install a relief valve (not shown) in a portion of the second pressure pipe 46c. By providing a relief valve, the lubricating oil pressure Po at low temperatures can be prevented from exceeding the limit value.

[0092] Figure 8 is a pressure balance diagram of the air seal device 10 according to the second embodiment. As described above, the stern tube sealing device 10A on the stern side forms an air seal space Ra, a rear seal oil space Ro, and a drain air seal space Ra in that order from the outside of the hull. Therefore, the pressure balance of the stern tube sealing device 10A is such that the air seal space Ra between the #1 and #2 seal rings and between the #3 and #4 seal rings is substantially at the same pressure. The pressure balance of the dual counter-rotating seal device 10B is such that the pressure difference between the #2 and #3 seal rings and the oil space in front of the #3 seal ring are in communication via a self-circulating system, making the pressure difference negligible and the pressures essentially equal.

[0093] (Oil recovery device 50) In Figure 6, the oil recovery device 50 includes a first oil recovery device 50A corresponding to the stern tube seal device 10A on the stern side, and a second oil recovery device 50B corresponding to the double reversing seal device 10B.

[0094] In this example, the auxiliary air tank 69 is shared by the first oil recovery device 50A and the second oil recovery device 50B.

[0095] Furthermore, the height of the intermediate piping 55 of the second oil recovery device 50B should be set, for example, 1 meter higher than that of the first oil recovery device 50A. This is because there is a difference between the outlet pressure and the actual pressure at the seal section in the stern tube sealing device 10A and the double-reverse sealing device 10B, and this difference is corrected and controlled by a common air control unit and auxiliary air tank. For example, the lubricating oil for stern tube bearings has nearly the same pressure at the seal and outlet, but the lubricating oil for counter-rotating bearings has a lower outlet pressure than at the seal due to pressure loss.

[0096] The other configurations of the first oil recovery device 50A and the second oil recovery device 50B are the same as those of the oil recovery device 50 in the first embodiment.

[0097] According to the embodiment of the present invention described above, by setting the upper end height of the riser pipe 54 to a height lower than the maximum draft + 2 m, a hydraulic pressure equivalent to the pipe height (for example, a hydrostatic pressure of +1 m or more and +3 m or less) can be applied to the oil bath space Rb communicating with the oil outlet 6d.

[0098] Furthermore, the seal differential pressure control device 60 works in conjunction with the water pressure Pd to apply a seal pressure Ps greater than the water pressure to the oil outlet 6d. This ensures that the lubricating oil pressure Po in the oil bath space Rb and the seal oil space Ro is always maintained at a seal pressure Ps (≈ water pressure + β) that is higher than the seal air pressure Pa (= water pressure + α), thereby ensuring an appropriate seal differential pressure at all times.

[0099] Therefore, even in small ships with limited engine room space, equipment can be positioned at a height that does not exceed the upper deck, and appropriate seal differential pressure can be maintained in ships with large draft changes.

[0100] Furthermore, the present invention provides the following effects. (1) In large vessels, costs can be reduced by eliminating the pressure tank (recessed tank) and recessed tanks, pumps, and coolers for bow-side seals that were previously required. (2) Equipment can be arranged at a height that does not exceed the height of the engine room, the upper deck, or the top of the funnel, making it possible to arrange equipment even on small ships with limited engine room space. (3) The lubricating oil pressure Po can be automatically controlled according to the draft, and an appropriate seal differential pressure can be maintained on ships with large draft changes.

[0101] It should be noted that the present invention is not limited to the embodiments described above, and various modifications can be made without departing from the spirit of the invention. [Explanation of Symbols]

[0102] A Seal air, A1 Drain air, Ac Control air, D, D1, D2 Drain, O Lubricating oil, Ob Stern tube lubricating oil, Oc Bow side stern tube seal oil, Pa Seal air pressure, Pb Bias pressure, Pd Draft pressure, Po Lubricating oil pressure, Ps Seal pressure, Ra Air seal space, Rb Oil bath space, Ro Aft seal oil space, Ro1 Forward seal oil space, Z Axis, 1 Marine propeller shaft, 1A Outer propeller shaft, 1B Inner propeller shaft, 2 Stern tube, 3 Propeller, 3A Fore propeller, 3B Aft propeller, 4 Stern, 5a, 5b Stern tube bearing, 6a Air supply port, 6b Drain outlet, 6c Oil supply port, 6d Oil outlet, 6e Bow side stern tube seal oil supply port, 7a Oil supply port, 10 Air seal device, 10A Stern side stern tube seal device, 10B Double counter-rotating seal device, 11 Seal member (seal ring), 14 Bow side stern tube seal device, 20 Air supply device, 22 Air control unit, 23 Air piping, 24, 24A, 24B Flow path, 25 Regulator, 26 Flow controller, 28 Air relay, 30 Drain recovery device, 30A Stern tube drain recovery device, 30B Double counter-rotating drain recovery device, 32, 32A, 32B Flow path, 33 Drain piping, 35 Drain recovery unit, 40 Oil supply device, 42 Oil tank, 44 Oil pump, 44a Check valve, 46 Oil pressure line, 46a Suction pipe, 46b First pressure pipe, 46c Second pressure pipe, 46d Third pressure pipe, 47, 47A, 47B, 48 Flow path, 50 Oil recovery device, 52, 52A,52B Flow path, 53 Confluence point, 54 Hydraulic pressure addition piping (riser piping), 56 Return piping, 56a Upper end, 57 Throttle mechanism, 57a Orifice, 57b Needle valve, 58 Bypass line, 60 Seal differential pressure control device, 60a Primary pressure detection port, 60b Back pressure detection port, 61 On / off valve, 62 Pressure regulating valve, 62a Piston, 62b Primary pressure detection chamber, 62c Atmospheric pressure detection chamber, 63 Check valve, 64 Needle valve, 65 Switching valve (three-way valve), 67 Pilot line, 68 Bias pressure line, 69 Auxiliary air tank, 69a Orifice, 69b Relief valve, 69c Drain outlet, 69d On / off valve, 70 Oil supply device, 72 Check valve, 74 Orifice, 77 External piping, 80 Reversing device, 82 Dual counter-rotating bearing, 100 marine shaft sealing device,

Claims

1. An air seal device having three or more sealing members in the axial direction between the marine propulsion shaft and the stern, which sequentially forms an air seal space, a seal oil space, and an oil bath space from the outside of the hull, An air supply device that supplies sealing air to the aforementioned air seal space, A drain recovery device for recovering drain from the aforementioned air seal space, An oil supply device that supplies oil to the seal oil space and the oil bath space, The system includes an oil recovery device for recovering oil from the oil bath space, The oil supply device comprises an oil tank that holds oil internally, an oil pump that pumps oil, and an oil pumping line that supplies oil from the oil tank to the oil bath space and the seal oil space. The aforementioned oil recovery device is It comprises a hydraulic pressure supply pipe extending upward from an oil discharge port provided in the stern tube and adding hydraulic pressure equivalent to the pipe height to the oil bath space, an intermediate pipe connected to the upper end of the hydraulic pressure supply pipe, and a return pipe connected to the intermediate pipe, with its upper end open to the atmosphere and its lower end connected to the oil tank, The upper end height of the aforementioned hydraulic pressure piping is set to a height lower than the maximum draft + 2m. A marine shaft seal device further comprising a seal differential pressure control device provided in the intermediate piping, which is linked to the draft pressure and applies a seal pressure greater than the draft pressure to the oil outlet.

2. The marine shaft seal device according to claim 1, wherein the air supply device has an air control unit that generates the seal air and controls its pressure.

3. The marine shaft seal device according to claim 2, wherein the air control unit has a flow controller that flows the seal air at a constant flow rate and controls the seal air pressure to a pressure higher than the draft pressure.

4. The marine shaft seal device according to claim 2, wherein the air control unit has an air relay that outputs a bias pressure control air with adjusted seal air pressure.

5. The seal differential pressure control device is A pressure regulating valve is provided in the aforementioned intermediate piping, A marine shaft seal device according to claim 1, further comprising a pilot line that transmits the oil pressure near the oil outlet to the primary pressure detection chamber of the pressure regulating valve.

6. The pressure regulating valve has a primary pressure detection chamber for detecting pilot pressure and an atmospheric pressure detection chamber for detecting atmospheric pressure. The marine shaft seal device according to claim 5, wherein the seal differential pressure control device comprises a bias pressure line that transmits the bias pressure of the control air or the seal air pressure to the atmospheric pressure detection chamber.

7. The marine shaft seal device according to claim 5, wherein the seal differential pressure control device has a check valve provided downstream of the pressure regulating valve in the intermediate piping.

8. The seal differential pressure control device is A bypass line that bypasses the pressure regulating valve and the check valve, A needle valve provided in the bypass line, The marine shaft sealing device according to claim 7, further comprising a switching valve provided at the confluence point of the downstream end of the bypass line and the intermediate piping.

9. The marine shaft sealing device according to claim 6, further comprising an auxiliary air tank provided in the bias pressure line.

10. The marine shaft sealing device according to claim 9, further comprising a relief valve provided in the auxiliary air tank.

11. The marine shaft sealing device according to claim 9, further comprising orifices provided before and after the auxiliary air tank in the bias pressure line.

12. The seal air pressure is automatically controlled to the draft pressure plus a little extra. The marine shaft seal device according to claim 1, wherein the seal pressure is automatically controlled to the draft pressure + β (β > α).

13. The marine shaft sealing device according to claim 1, wherein the marine propulsion shaft is the outer propeller shaft of a contra-rotating propeller system.

14. The air seal device comprises a stern-side stern tube seal device provided between the outer propeller shaft and the stern tube, and a counter-rotating seal device provided between the forward propeller and the aft propeller. The aforementioned stern tube sealing device forms a drain air seal space between the seal oil space and the oil bath space from the outside of the hull. The marine shaft seal device according to claim 13, wherein the double-rotating seal device sequentially forms the air seal space, the seal oil space, and the oil bath space from the outside of the hull.

15. An air seal device having three or more sealing members in the axial direction between the marine propulsion shaft and the stern, which sequentially forms an air seal space, a seal oil space, and an oil bath space from the outside of the hull, An air supply device that supplies sealing air to the aforementioned air seal space, A drain recovery device for recovering drain from the aforementioned air seal space, An oil supply device that supplies oil to the seal oil space and the oil bath space, The system includes an oil recovery device for recovering oil from the oil bath space, The oil supply device comprises an oil tank that holds oil internally, an oil pump that pumps oil, and an oil pumping line that supplies oil from the oil tank to the oil bath space and the seal oil space. The aforementioned oil recovery device is It comprises a hydraulic pressure supply pipe extending upward from an oil discharge port provided in the stern tube and adding hydraulic pressure equivalent to the pipe height to the oil bath space, an intermediate pipe connected to the upper end of the hydraulic pressure supply pipe, and a return pipe connected to the intermediate pipe, with its upper end open to the atmosphere and its lower end connected to the oil tank, The upper end height of the aforementioned hydraulic pressure piping is set to a height lower than the maximum draft + 2m. Furthermore, the intermediate piping is equipped with a seal differential pressure control device that is linked to the draft pressure and applies a seal pressure greater than the draft pressure to the oil outlet, The seal differential pressure control device has a pressure regulating valve provided in the intermediate piping, The oil pressure near the oil outlet is transmitted to the primary pressure detection chamber of the pressure regulating valve, and, A seal differential pressure control method comprising transmitting a bias pressure, which is adjusted by an air relay in conjunction with the aforementioned draft pressure, to the atmospheric pressure detection chamber of the pressure regulating valve.

16. A contra-rotating propeller system equipped with the marine shaft seal device described in claim 1.

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