Sealing Device

Abstract

Provided is a sealing device with which pressure control is simple.　The sealing device 1 comprises a cylindrical body 10 through which a rotary shaft 2 is inserted, and a sealing ring 25 which is attached to the cylindrical body 10 and seals a space between the cylindrical body 10 and the rotary shaft 2, the sealing device having at least two sealing spaces S5, S6 with the sealing ring 25 interposed therebetween. A sealing fluid OL3 is introduced from the outside into one sealing space S5, and the one sealing space S5 and the other sealing space S6 are communicated by a flow passage 6. The flow passage 6 is provided with a pressure adjustment device 30 which adjusts the pressure of the sealing fluid OL3 introduced into the one sealing space S5 so as to introduce the sealing fluid into the other sealing space S6.

Description

[Technical Field]

[0001] The present invention relates to a seal device, and more particularly to a seal device that seals the relative rotation points of rotary machines that are used in ship propulsion machines, tidal current power generators, and the like. [Background technology]

[0002] Some sealing devices installed in rotating machinery such as those used in ship propulsion units and tidal current generators seal annular gaps formed at points of relative rotation to prevent sealed fluids inside the machinery, such as lubricating oil, from leaking outside the ship and to prevent external fluids, such as seawater, from entering the machinery.

[0003] For example, the seal devices in Patent Document 1 are provided at both axial ends of a stern tube that supports a bearing for a propeller shaft, and lubricating oil is sealed inside the stern tube by the seal devices on both sides. The seal devices include a cylindrical member and first to third seal rings that are attached to the inner peripheral surface of the cylindrical member at intervals in the axial direction. Each of these seal rings is a lip seal, and their inner diameter ends slide against the outer peripheral surface of a liner that is fitted and fixed to the propeller shaft.

[0004] A first space is defined between the first seal ring and the second seal ring on the outboard side. A fluid having a fluid pressure higher than seawater pressure is supplied to the first space from an external first supply device. A second space is defined between the second seal ring and the third seal ring on the inboard side. A fluid having a fluid pressure higher than the fluid pressure in the first space and the hydraulic pressure in the stern tube is supplied to the second space from an external second supply device. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] WO 2018 / 216155 (page 7, Figure 2) Summary of the Invention [Problem to be solved by the invention]

[0006] In a sealing device such as that described in Patent Document 1, the fluid pressure in the second space, which is higher than the fluid pressure in the first space, presses the lip portion of the second seal ring against the liner, sealing the first space and the second space, thereby preventing leakage of lubricating oil outside the machine.

[0007] However, in a sealing device such as that disclosed in Patent Document 1, the first space is supplied with fluid whose pressure is adjusted by a first supply device, and the second space is supplied with fluid whose pressure is adjusted by a second supply device. Therefore, when the seawater pressure fluctuates, the fluid pressures of the first and second spaces must be adjusted individually, making pressure control of the first and second spaces complicated.

[0008] The present invention has been made in view of these problems, and has as its object to provide a sealing device in which pressure control is simple. [Means for solving the problem]

[0009] In order to solve the above problems, the sealing device of the present invention comprises: A seal device comprising: a cylindrical body through which a rotating shaft is inserted; and a seal ring attached to the cylindrical body to seal between the cylindrical body and the rotating shaft, the seal device having at least two seal spaces sandwiched between the seal ring, One of the sealed spaces is introduced with a sealed fluid from the outside. The one sealed space and the other sealed space are connected by a flow path, and the flow path is provided with a pressure adjustment device that adjusts the pressure of the sealed fluid introduced into the one sealed space and introduces it into the other sealed space. According to this, the adjusted sealing fluid introduced into one of the sealing spaces can be pressure-adjusted by the pressure adjusting device and introduced into the other sealing space, so that the pressures of the one sealing space and the other sealing space can be easily adjusted to appropriate pressures.

[0010] The flow path may be formed in the cylindrical body. This eliminates the need to arrange piping or the like outside the cylindrical body to connect to the other sealed space, allowing the structure of the sealing device to be made compact.

[0011] The other seal space may be arranged on the inboard side of the one seal space, and an oil chamber may be arranged further inboard than the other seal space. This allows oil that attempts to leak from the oil chamber inside the machine to the outside to be recovered in the other low-pressure seal space, and since one high-pressure seal space is located outside the other seal space, oil leakage to the outside of the machine can be prevented.

[0012] The one seal space and the other seal space may be adjacent to each other, the seal ring may be a lip seal, and the sealing force may be increased by the pressure difference between the one seal space and the other seal space. This configuration effectively prevents fluid leakage because the sealing force of the lip seal is increased by the pressure difference between one sealed space and the other sealed space. In addition, it is difficult for fluid to move between the one sealed space and the other sealed space from places other than the flow path, making it easy to adjust the pressure between the one sealed space and the other sealed space.

[0013] The fluid in the other sealed space may be able to be discharged to the outside. This allows the fluid in the other sealed space to be discharged to the outside.

[0014] The pressure regulating device may be a valve with a spring-biased valve body. This allows the opening degree to be adjusted in accordance with fluctuations in the differential pressure between one sealed space and the other sealed space. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a cross-sectional view showing a sealing device according to a first embodiment of the present invention. [Figure 2] FIG. 2 is an exploded view showing the structure of the pressure regulating valve. [Figure 3]FIG. 4 is a schematic diagram showing the pressure state of each seal space. [Figure 4] FIG. 6 is a cross-sectional view showing a sealing device according to a second embodiment of the present invention. [Figure 5] FIG. 10 is a cross-sectional view showing a sealing device according to a third embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0016] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A sealing device according to an embodiment of the present invention will be described below with reference to the accompanying drawings. [Example]

[0017] A sealing device according to a first embodiment will be described with reference to Figures 1 to 3. In this embodiment, a sealing device used in a stern tube of a ship will be described as an example. The left side of Figure 1 will be the stern side (outboard side) of the sealing device, and the right side of Figure 1 will be the bow side (inboard side) of the sealing device.

[0018] As shown in Fig. 1, the sealing device 1 according to the present invention is a shaft sealing device for a ship propulsion machine. A bearing (not shown) is disposed inside a stern tube 100 through which a propeller shaft 2 serving as a rotating shaft having a propeller 3 for propulsion is inserted, and lubricating oil OL1 serving as a sealed fluid is sealed inside the stern tube 100.

[0019] A seal device 1 is disposed on the stern side of the stern tube 100 to prevent lubricating oil OL1, which serves as an internal fluid, from leaking out of the ship from between the stern tube 100 and a liner 4 fitted and fixed to the propeller shaft 2, and to prevent seawater SW1, which serves as an external fluid, from entering the ship. The liner 4 in this embodiment constitutes a part of the propeller shaft 2.

[0020] In addition, a sealing device (not shown) is arranged on the bow side of the stern tube 100 to prevent lubricating oil from leaking from between the stern tube 100 and the propeller shaft 2 into the machinery room inside the ship.

[0021] As shown in FIG. 1, the sealing device 1 is mainly composed of a housing 10 as a cylindrical body, a first lip seal 21 to a sixth lip seal 26, and a pressure reducing valve 30 as a pressure adjusting device.

[0022] The housing 10 is formed into a substantially cylindrical shape by, in order from the stern side, a first divided housing 10a, a second divided housing 10b, a third divided housing 10c, a fourth divided housing 10d, a fifth divided housing 10e, a sixth divided housing 10f, and a seventh divided housing 10g, which are fitted together in the axial direction and connected together with bolts (not shown) or the like. A flange portion formed on the seventh divided housing 10g on the bow side of the housing 10 is fixed to the stern tube 100 with bolts (not shown) or the like.

[0023] The outer diameter portion of the first lip seal 21 is held in a sealed state between the first split housing 10a and the second split housing 10b. The outer diameter portion of the second lip seal 22 is held in a sealed state between the second split housing 10b and the third split housing 10c. The outer diameter portion of the third lip seal 23 is held in a sealed state between the third split housing 10c and the fourth split housing 10d.

[0024] The outer diameter portion of the fourth lip seal 24 is held in a sealed state between the fourth split housing 10d and the fifth split housing 10e. The outer diameter portion of the fifth lip seal 25 is held in a sealed state between the fifth split housing 10e and the sixth split housing 10f. The outer diameter portion of the sixth lip seal 26 is held in a sealed state between the sixth split housing 10f and the seventh split housing 10g.

[0025] Additionally, a seal 5 is attached to the inner peripheral surface of the first split housing 10a to prevent the intrusion of foreign matter.

[0026] Between the housing 10 and the liner 4, a plurality of seal spaces are defined in the axial direction by the first lip seal 21 to the sixth lip seal 26.

[0027] More specifically, a first seal space S1 is formed between the seal 5 and the first lip seal 21. A second seal space S2 is formed between the first lip seal 21 and the second lip seal 22. A third seal space S3 is formed between the second lip seal 22 and the third lip seal 23. A fourth seal space S4 is formed between the third lip seal 23 and the fourth lip seal 24.

[0028] A fifth seal space S5 as one of the seal spaces is formed between the fourth lip seal 24 and the fifth lip seal 25. A sixth seal space S6 as the other of the seal spaces is formed between the fifth lip seal 25 and the sixth lip seal 26. An oil chamber S7 inside the stern tube 100 is formed on the inboard side of the sixth seal space S6.

[0029] The first lip seal 21 is disposed so that its lip portion 21a faces outboard, and the pressure on the inboard side of the first lip seal 21, i.e., the pressure within the first seal space S1, acts as part of the tightening pressure on the lip portion 21a. The second lip seal 22, fourth lip seal 24, fifth lip seal 25, and sixth lip seal 26 have substantially the same configuration as the first lip seal 21.

[0030] In addition, the third lip seal 23 is positioned so that its lip portion 23a faces the inboard side of the ship, and the pressure on the inboard side of the third lip seal 23, i.e., the pressure within the fourth seal space S4, acts as part of the tightening pressure on the lip portion 23a.

[0031] A second seal space S2 is formed in the second split housing 10b.

[0032] The third split housing 10c is formed with a communication hole 13 that connects the third sealing space S3 to an external air introduction device 41, and a discharge hole (not shown) that connects the third sealing space S3 to an external discharge tank 42.

[0033] A communication hole 14 that connects the fourth seal space S4 and the first oil supply device 43 is formed in the fourth split housing 10d.

[0034] The fifth split housing 10e is formed with a communication hole (not shown) that connects the fifth sealing space S5 with the second oil supply device 44, and a communication hole 61 that forms part of the flow path 6 that connects the fifth sealing space S5 with the sixth sealing space S6.

[0035] The communication hole 61 is generally T-shaped, with a radially penetrating portion and a portion that branches off toward the inboard side halfway through the radially penetrating portion of the communication hole 61. A pressure reducing valve 30, which will be described later, is attached to the outer diameter side of the radially penetrating portion of the communication hole 61.

[0036] The sixth split housing 10f is also formed with a communication hole 62 that connects the fifth seal space S5 and the sixth seal space S6 and that, together with the communication hole 61, constitutes part of the flow path 6. The communication hole 62 extends in an inverted L shape from the branched portion of the communication hole 61 and communicates with the sixth seal space S6.

[0037] The flow path 6 of the present invention is constituted by a communication hole 61 and a communication hole 62, and communicates the fifth sealing space S5 with the sixth sealing space S6.

[0038] Additionally, a discharge hole (not shown) that communicates with the sixth seal space S6 and an external discharge tank 45 is formed in the sixth split housing 10f.

[0039] In this embodiment, the discharge tank 42 and the discharge tank 45 are provided separately, but the same discharge tank may be used for both purposes.

[0040] As shown in Figures 1 and 2, the pressure reducing valve 30 is a poppet valve and is mainly composed of a fixed plug 31, a pressure adjusting rod 32, a push plate 33, a spring 34, a valve body 35, a valve seat member 36, and a cap 37.

[0041] The fixing plug 31 is screwed and fixed via a packing 30a to the outer diameter side of the portion of the communication hole 61 of the fifth split housing 10e that penetrates in the radial direction.

[0042] The pressure adjusting rod 32 is screwed and fixed to the fixed plug 31 so that its position can be adjusted. A fixing nut 30c is screwed onto the portion of the pressure adjusting rod 32 that protrudes outward beyond the fixed plug 31 via a spring washer 30b, preventing the screwed state between the pressure adjusting rod 32 and the fixed plug 31 from loosening due to vibration or the like.

[0043] A cap 37 is fitted and fixed onto the outside of the fixed plug 31 via a packing 30d.

[0044] A valve element 35 is disposed on the inner diameter side of the pressure adjusting rod 32 in the fixed plug 31 via a push plate 33 and a spring 34 so as to be able to move toward and away from a valve seat member 36 .

[0045] A valve seat member 36 is threadably fixed to the inner diameter side of the radially penetrating portion of the communication hole 61 of the fifth split housing 10e. This valve seat member 36 has a valve seat, and the opening degree of the flow path 6 can be adjusted by moving the valve element 35 toward and away from the valve seat.

[0046] Furthermore, by adjusting the relative position of the pressure adjusting rod 32 with respect to the fixed plug 31, the biasing force of the spring 34 that biases the valve body 35 toward the valve seat member 36 can be adjusted.

[0047] Next, the fluid pressure in each seal space will be described.

[0048] As shown in FIG. 3, seawater SW1 flows into the first seal space S1 through the gap between the seal 5 and the liner 4, and the pressure in the first seal space S1 is approximately the same as that in the outboard space S8.

[0049] Air A from a third seal space S3 (described later) is blown out from between the second lip seal 22 and the liner 4 and introduced into the second seal space S2. The air introduced into the second seal space S2 is blown out toward the first seal space from between the first lip seal 21 and the liner 4. The pressure in the second seal space S2 is adjusted to be higher than seawater pressure and equal to or lower than the pressure of the fourth seal space S4.

[0050] Air A having a pressure lower than the pressure in the second sealing space S2 and the pressure in the fourth sealing space S4 is constantly introduced into the third sealing space S3 from the air introducing device 41. The air introducing device 41 detects the pressure in the second sealing space S2 and the pressure in the fourth sealing space S4 using a pressure sensor (not shown), and adjusts the pressure of the air A so that it is lower than the detected pressure in the second sealing space S2 and the fourth sealing space S4.

[0051] This increases the sealing force of the second lip seal 22 because the pressure in the third seal space S3 is lower than the pressure in the second seal space S2, which is the clamping pressure of the lip portion 22a of the second lip seal 22. Similarly, the pressure in the third seal space S3 is lower than the pressure in the fourth seal space S4, which is the clamping pressure of the lip portion 23a of the third lip seal 23, so the sealing force of the third lip seal 23 can be increased.

[0052] Furthermore, since the third sealing space S3 is in communication with the discharge tank 42, even if the seawater SW2 in the second sealing space S2 and / or the lubricating oil OL2 in the fourth sealing space S4 flow into the third sealing space S3, they can be recovered in the external discharge tank 42. An open / close valve is formed in the flow path between the third sealing space S3 and the discharge tank 42, so that the communication state can be changed as needed.

[0053] The lubricating oil OL2 is constantly introduced from the first oil supply device 43 into the fourth seal space S4 at a pressure slightly higher than the pressure in the oil chamber S7.

[0054] Lubricating oil OL3, whose pressure is lower than that in the fourth seal space S4, is constantly introduced into the fifth seal space S5 from the second oil supply device 44. The pressure in the fifth seal space S5 is adjusted by the throttling amount of the pressure reducing valve 30, and is lower than the pressure in the fourth seal space S4.

[0055] According to this, the pressure in the fifth seal space S5 is lower than the pressure in the fourth seal space S4, which is the clamping pressure of the lip portion 24a of the fourth lip seal 24, so the sealing force of the fourth lip seal 24 can be increased.

[0056] The valve element 35 of the pressure reducing valve 30 is pushed up by the pressure in the fifth sealing space S5, and the lubricating oil OL3 in the fifth sealing space S5 passes through the part of the flow path 6 that is throttled by the pressure reducing valve 30 and flows into the sixth sealing space S6.

[0057] That is, since the lubricating oil OL4, whose pressure has been reduced due to pressure loss when passing through the pressure reducing valve 30, flows into the sixth sealing space S6, the pressure in the sixth sealing space S6 becomes lower than the pressure in the fifth sealing space S5.

[0058] According to this, the pressure in the sixth seal space S6 is lower than the pressure in the fifth seal space S5, which is the clamping pressure of the lip portion 25a of the fifth lip seal 25, so the sealing force of the fifth lip seal 25 can be increased.

[0059] Since the pressure in the sixth sealing space S6 is lower than the pressure in the oil chamber S7, the lubricating oil OL1 in the oil chamber S7 may enter the sixth sealing space S6, but the lubricating oil OL1 that has entered the sixth sealing space S6 can be discharged to the discharge tank 45. An open / close valve is provided in the flow path between the sixth sealing space S6 and the discharge tank 45, so that the communication state can be changed as needed.

[0060] As described above, the lubricating oil OL3 adjusted by the second oil supply device 44 and introduced into the fifth seal space S5 can be reduced in pressure by the pressure reducing valve 30 and introduced into the sixth seal space S6, so the fifth seal space S5 and the sixth seal space S6 can each be easily adjusted to an appropriate pressure. Furthermore, since there is no need for a separate oil supply device different from the second oil supply device 44, the structure can be made compact.

[0061] Furthermore, the flow path 6 is provided in the housing 10. This eliminates the need to provide piping or a pressure reducing valve 30 outside the housing 10 to connect the fifth sealing space S5 and the sixth sealing space S6, thereby making the structure even more compact.

[0062] Furthermore, since the sixth seal space S6 is arranged on the inboard side of the fifth seal space S5 and the oil chamber S7 is arranged further inboard from the sixth seal space S6, the lubricating oil OL1 that attempts to leak from the oil chamber S7 to the outboard side can be recovered in the low-pressure sixth seal space S6, and since the high-pressure fifth seal space S5 is arranged outboard of the sixth seal space S6, leakage of the lubricating oil OL1 to the outboard side can be prevented.

[0063] In addition, since the sixth seal space S6 is supplied with the same lubricating oil as the oil chamber S7, there is no problem even if the oil leaks from the oil chamber S7 into the sixth seal space S6.

[0064] Furthermore, a low-pressure third sealing space S3 into which air A is introduced is disposed between the fourth sealing space S4 and the second sealing space S2, so that even if lubricating oil or seawater leaks into the third sealing space S3, it can be recovered, eliminating the risk of leakage outside the ship. Furthermore, the lubricating oil and seawater recovered in the third sealing space S3 can be discharged into the discharge tank 42, preventing them from overflowing from the third sealing space S3 into the fourth sealing space S4 or the second sealing space S2.

[0065] Furthermore, the fifth seal space S5 and the sixth seal space S6 are adjacent to each other, and the fifth lip seal 25 that separates the fifth seal space S5 and the sixth seal space S6 has a sealing force that increases with the pressure difference between the fifth seal space S5 and the sixth seal space S6, effectively preventing leakage of lubricating oil. Furthermore, because lubricating oil is less likely to leak from the gap between the fifth lip seal 25 and the liner 4, it is easy to adjust the pressure in the fifth seal space S5 and the sixth seal space S6.

[0066] Furthermore, the sixth sealing space S6 can be connected to the discharge tank 45 using an on-off valve, allowing the lubricating oil OL4 to be discharged to the outside. This allows the fluid pressure in the sixth sealing space S6 to be adjusted by opening and closing the on-off valve.

[0067] Furthermore, since the valve element 35 of the pressure reducing valve 30 is biased toward the valve seat member 36 by the spring 34, the opening degree is adjusted in accordance with fluctuations in the differential pressure between the fifth sealing space S5 and the sixth sealing space S6, and the pressure in the fifth sealing space S5 and the sixth sealing space S6 can be appropriately adjusted.

[0068] Although the first embodiment exemplifies a configuration in which the first to sixth sealing spaces S1 to S6 are provided, it is sufficient that at least the fifth sealing space S5 and the sixth sealing space S6 are provided. Furthermore, the fifth sealing space S5 may be located on the inboard side, and the sixth sealing space S6 may be located on the outboard side.

[0069] Furthermore, in this embodiment 1, a configuration in which the fifth sealing space S5 and the sixth sealing space S6 are adjacent to each other has been exemplified, but a different sealing space may be formed between the fifth sealing space S5 and the sixth sealing space S6.

[0070] Furthermore, in this embodiment 1, an example is given of a form in which a flow path 6 is formed in the housing 10 that connects the fifth sealing space S5 and the sixth sealing space S6, but the fifth sealing space S5 and the sixth sealing space S6 may also be connected by connecting a pipe provided outside the housing 10 to an opening in the housing.

[0071] In addition, in the first embodiment, the fourth seal space S4, the fifth seal space S5, and the sixth seal space S6 are filled with the same lubricating oil as that in the oil chamber S7, but this is not limiting, and a fluid different from that in the oil chamber S7 may be filled in. In this case, it is preferable that the lip portion of the sixth lip seal 26 is arranged to face the high-pressure side of the sixth seal space S6 and the oil chamber S7.

[0072] Furthermore, the pressure reducing valve 30 is assembled by screwing from the outside of the housing 10. This allows the assembly and replacement of the pressure reducing valve 30 to be easily performed.

[0073] Furthermore, since the pressure adjusting rod 32 of the pressure reducing valve 30 can be adjusted from outside the housing 10, the biasing force of the spring 34 can be easily adjusted. [Example]

[0074] Next, a stern tube seal device according to a second embodiment will be described with reference to Fig. 4. Note that a description of the same configuration as in the first embodiment will be omitted.

[0075] 4, the sealing device 201 of the second embodiment is disposed on the bow side of the stern tube 100, and prevents the lubricating oil in the oil chamber S7 from leaking into the machinery room S9 inside the ship from between the stern tube 100 and a liner 204 fitted and fixed to the outside of the propeller shaft 2. The machinery room S9 is an atmospheric space.

[0076] The sealing device 201 is mainly composed of a housing 210 as a cylindrical body, a first lip seal 221 to a third lip seal 223, and a pressure reducing valve 230 as a pressure adjusting device.

[0077] The housing 210 is formed into a substantially cylindrical shape by, in order from the bow side, a first divided housing 210a, a second divided housing 210b, a third divided housing 210c, and a fourth divided housing 210d, which are fitted together in the axial direction and connected together with bolts (not shown) or the like. A flange portion formed on the fourth divided housing 210d on the stern side of the housing 210 is fixed to the stern tube 100 with bolts 7.

[0078] The outer diameter portion of the first lip seal 221 is held in a sealed state between the first split housing 210a and the second split housing 210b. The outer diameter portion of the second lip seal 222 is held in a sealed state between the second split housing 210b and the third split housing 210c. The outer diameter portion of the third lip seal 223 is held in a sealed state between the third split housing 210c and the fourth split housing 210d.

[0079] The lip portions of the first lip seal 221 to the third lip seal 223 face outboard.

[0080] A seal space S11 is formed between the first lip seal 221 and the second lip seal 222. A seal space S12 is formed between the second lip seal 222 and the third lip seal 223. The outboard side of the third lip seal 223 forms an oil chamber S7.

[0081] A flow path 206 that connects the seal spaces S11 and S12 is formed between the second divided housing 210b and the third divided housing 210c.

[0082] Additionally, a pressure reducing valve 230 is attached to the third divided housing 210c so as to be able to open and close the flow path 206. The pressure reducing valve 230 has substantially the same configuration as the pressure reducing valve 30 of the first embodiment, and therefore a detailed description thereof will be omitted.

[0083] The sealed space S11 is in communication with the discharge tank 245. An orifice 8 is provided in the flow path between the sealed space S11 and the discharge tank 245.

[0084] The seal space S12 is also in communication with an oil supply device 244. The oil supply device 244 is configured to constantly introduce lubricating oil at a pressure slightly lower than the pressure in the oil chamber S7 into the seal space S12.

[0085] The lubricating oil in the sealed space S12 is introduced into the sealed space S11 through a flow path 206 in which the opening of the pressure reducing valve 30 is adjusted according to the pressure difference between the sealed spaces S11 and S12. As a result, the pressure in the sealed space S11 becomes lower than that of the sealed space S12.

[0086] That is, the order of fluid pressure is oil chamber S7 > seal space S12 > seal space S11 > machinery chamber S9. This improves the sealing performance of the third lip seal 223 due to the pressure difference between the oil chamber S7 and seal space S12, improves the sealing performance of the second lip seal 222 due to the pressure difference between seal space S12 and seal space S11, and improves the sealing performance of the first lip seal 221 due to the pressure difference between seal space S11 and machinery chamber S9. This prevents lubricating oil from leaking into the machinery chamber S9. [Example]

[0087] Next, a stern tube seal device according to a third embodiment will be described with reference to Fig. 5. Note that a description of the same configuration as in the first embodiment will be omitted.

[0088] As shown in FIG. 5, the sealing device 301 of the third embodiment is mainly composed of a housing 310 as a cylindrical body, a first lip seal 321 to a fourth lip seal 324, and pressure reducing valves 330A and 330B as pressure adjusting devices.

[0089] The housing 310 is formed into a generally cylindrical shape by, in order from the stern side, a first divided housing 310a, a second divided housing 310b, a third divided housing 310c, a fourth divided housing 310d, and a fifth divided housing 310e, which are fitted together in the axial direction and connected together with bolts (not shown) or the like. A flange portion formed on the fifth divided housing 310e on the stern side of the housing 310 is fixed to the stern tube 100 with bolts 9.

[0090] The outer diameter portion of the first lip seal 321 is hermetically held between the first split housing 310a and the second split housing 310b. The outer diameter portion of the second lip seal 322 is hermetically held between the second split housing 310b and the third split housing 310c. The outer diameter portion of the third lip seal 323 is hermetically held between the third split housing 310c and the fourth split housing 310d. The outer diameter portion of the fourth lip seal 324 is hermetically held between the fourth split housing 310d and the fifth split housing 310e.

[0091] The lip portions of the first lip seal 321 to the third lip seal 323 face outboard, and the lip portion of the fourth lip seal 324 faces inboard.

[0092] A sealing space S31 is formed between the first lip seal 321 and the second lip seal 322. A sealing space S32 is formed between the second lip seal 322 and the third lip seal 323. A sealing space S33 is formed between the third lip seal 323 and the fourth lip seal 324.

[0093] The second divided housing 310b and the third divided housing 310c are provided with a flow path 361 that connects the sealed spaces S31 and S32. The third divided housing 310c and the fourth divided housing 310d are provided with a flow path 362 that connects the sealed spaces S32 and S33.

[0094] Pressure reducing valve 330A is attached to second divided housing 310b so as to be able to open and close flow path 361. Pressure reducing valve 330B is attached to third divided housing 310c so as to be able to open and close flow path 362. Note that pressure reducing valves 330A and 330B have substantially the same configuration as pressure reducing valve 30 of embodiment 1, and therefore detailed description thereof will be omitted.

[0095] Water W is sealed in the internal space S37 of the stern tube 100, and the water W enhances the lubrication of the bearings.

[0096] A storage tank 341 for storing water is disposed outside the internal space S37. This storage tank 341 is connected to a pump 342. The pump 342 is capable of pressurizing and introducing the water in the storage tank 341 into the internal space S37 and the sealed space S31. In the third embodiment, the pressure of the water W introduced into the sealed space S31 is lower than the pressure of the seawater SW in the outboard space S38.

[0097] The water W introduced into the sealed space S31 is depressurized by the pressure-reducing valve 330A and introduced into the sealed space S32. The water W introduced into the sealed space S32 is depressurized by the pressure-reducing valve 330B and introduced into the sealed space S33. That is, the pressure in each space is as follows: outboard space S38 > sealed space S31 > sealed space S32 > sealed space S33. The pressure in the sealed space S33 is lower than that in the internal space S37.

[0098] According to this, the pressure difference between the outboard space S38 and the seal space S31 improves the sealing ability of the first lip seal 321, the pressure difference between the seal space S31 and the seal space S32 improves the sealing ability of the second lip seal 322, the pressure difference between the seal space S32 and the seal space S33 improves the sealing ability of the third lip seal 323, and the pressure difference between the seal space S33 and the internal space S37 improves the sealing ability of the fourth lip seal 324. Therefore, seawater SW can be prevented from flowing into the internal space S37.

[0099] The water W introduced into the sealed space S33 is discharged into the storage tank 341. The water W in the internal space S37 is also discharged into the storage tank 341.

[0100] In the third embodiment, the pressure of the water W introduced into the sealed space S31 is lower than the pressure of the seawater SW in the outboard space S38, but the pressure in the sealed space S31 and the outboard space S8 may be the same, or the pressure of the water W introduced into the sealed space S31 may be higher than the pressure of the seawater SW in the outboard space S38. This is because the water W is fresh water and therefore there is no problem if it is discharged into the outboard space S38.

[0101] Furthermore, in the third embodiment, the three sealed spaces S31, S32, and S33 are in communication with each other, but four or more sealed spaces may be in communication with each other.

[0102] Furthermore, in the third embodiment, the pressure in each seal space is reduced toward the inboard side, but the pressure in each seal space may be reduced toward the outboard side.

[0103] Although the embodiments of the present invention have been described above with reference to the drawings, the specific configuration is not limited to these embodiments, and the present invention also includes modifications and additions that do not deviate from the gist of the present invention.

[0104] For example, in the above-described Examples 1 to 3, the external fluid is seawater, but this can be freely changed to, for example, fresh water, oil, air, gas, etc. Furthermore, the internal fluid is not limited to lubricating oil or water, but may also be air, gas, etc.

[0105] Furthermore, in the above-described Examples 1 to 3, the lip seal is in sliding contact with the outer peripheral surface of a liner fitted onto the propeller shaft, but this is not limiting, and the lip seal may be in direct sliding contact with the outer peripheral surface of the propeller shaft 2 without using a liner.

[0106] In addition, in the above-described Examples 1 to 3, a pressure reducing valve has been described as an example of the pressure adjusting device, but a throttle mechanism such as an orifice may also be used. Furthermore, the pressure adjusting device is not limited to one that reduces the pressure from one sealed space and supplies it to the other sealed space, but may be one that increases the pressure and supplies it.

[0107] Furthermore, the pressure reducing valve is not limited to a poppet valve, but may be a spool valve or the like.

[0108] Furthermore, each seal ring is not limited to one configured as a lip seal, but may be, for example, an end face seal. [Explanation of symbols]

[0109] 1 Sealing device 2 Propeller shaft (rotating shaft) 6 Flow path 10 Housing (cylindrical body) 25 5th lip seal (seal ring) 30 Pressure reducing valve (pressure regulator) 34 Spring 35 Valve body 36 Valve seat member 41 Air introduction device 42 Discharge Tank 43 1st oil supply device 44 2nd oil supply device 45 Discharge Tank 100 Stern tube S5 Fifth seal space (one of the seal spaces) S6 Sixth seal space (other seal space) S7 oil chamber S8 Extravehicular space

Claims

1. A seal device comprising: a cylindrical body through which a rotating shaft is inserted; and a seal ring attached to the cylindrical body to seal between the cylindrical body and the rotating shaft, the seal device having at least two seal spaces sandwiched between the seal ring, One of the sealed spaces is introduced with a sealed fluid from the outside. A sealing device in which the one sealed space and the other sealed space are connected by a flow path, and the flow path is provided with a pressure adjustment device that adjusts the pressure of the sealed fluid introduced into the one sealed space and introduces the sealed fluid into the other sealed space.

2. The sealing device according to claim 1 , wherein the flow path is formed in the cylindrical body.

3. 2. The sealing device according to claim 1, wherein the other seal space is disposed on the inboard side of the one seal space, and an oil chamber is disposed further inboard than the other seal space.

4. 2. The sealing device according to claim 1, wherein the one seal space and the other seal space are adjacent to each other, the seal ring is a lip seal, and the sealing force is increased by the pressure difference between the one seal space and the other seal space.

5. 2. The seal device according to claim 1, wherein the fluid in the other seal space can be discharged to the outside.

6. 6. A sealing device according to claim 1, wherein the pressure adjusting device is a valve whose valve body is spring-biased.

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