Bearing for propeller shaft of ship, tail pipe bearing arrangement, propulsion device and method for operating propulsion device

Abstract

A bearing (1) for radially supporting a propeller shaft (22) of a ship (20) comprises a plurality of lubrication holes (2a, 2b, 2c, 4a, 4b, 4c) extending from an outer surface of the bearing (1) to an inner surface of the bearing (1) to allow a flow of a lubrication medium between the inner surface and the outer surface, the lubrication holes (2a, 2b, 2c, 4a, 4b, 4c) comprise a first set of lubrication holes (2) leading onto the inner surface of the bearing (1) on a first side of the bearing (1) and a second set of lubrication holes (4) leading onto the inner surface of the bearing (1) on a second side of the bearing (1). The bearing (1) further comprises at least one lubrication inlet (8, 11) leading to an inner surface of the bearing (1) and configured to allow a lubrication medium to be introduced onto the inner surface independently of the first set of lubrication holes (2) and the second set of lubrication holes (4).

Description

Technical Field

[0001] The present invention relates to a bearing for radially supporting a propeller shaft of a ship as claimed in claim 1. The present invention also relates to a stern tube bearing arrangement for a ship, a propulsion device for a ship, and a method of operating a propulsion device. Background Art

[0002] A typical ship's propulsion system includes a propeller connected to the crankshaft of the ship's main engine via a propeller shaft. The propeller is attached to the propeller shaft. To allow the propeller shaft to pass through the ship's hull, the ship is equipped with a stern tube. The stern tube is a hollow tube located at the lower part of the ship's stern. Stern tube bearings are arranged within the stern tube to radially support the propeller shaft. To prevent direct contact between the stern tube bearing surface and the propeller shaft, the stern tube bearings are lubricated. They can be water- or oil-lubricated.

[0003] Oil-lubricated stern tube bearings are lubricated by the rotational motion of the propeller shaft. Typical conventional bearings include lubrication holes extending through the bearing housing. As the propeller shaft rotates, it creates a pumping effect that draws lubricating oil into the bearing, forming an oil film between the propeller shaft and the inner surface of the bearing.

[0004] While conventional lubrication systems are simple and work adequately under many operating conditions, lubrication is not always optimal. The load on the bearing is uneven and varies depending on the operating conditions. Insufficient lubrication of the stern tube bearing can lead to excessive wear or failure of the bearing. Summary of the Invention

[0005] An object of the present invention is to provide an improved bearing for radially supporting a propeller shaft of a vessel. Other objects of the present invention are to provide an improved stern tube bearing arrangement for a vessel, a propulsion arrangement for a vessel and a method of operating a propulsion arrangement.

[0006] A bearing according to the present invention is configured to be installed within a stern tube of a vessel and, when installed, has a top, a bottom, a first side extending from the top to the bottom along a first circumferential direction of the bearing, and a second side extending from the top to the bottom along a second circumferential direction opposite the first circumferential direction. The bearing includes a plurality of lubrication holes extending from an outer surface of the bearing to an inner surface of the bearing, for allowing a lubricating medium to flow between the inner surface and the outer surface, the lubrication holes including a first set of lubrication holes opening into the inner surface of the bearing on a first side of the bearing and a second set of lubrication holes opening into the inner surface of the bearing on a second side of the bearing. The bearing also includes at least one lubrication inlet opening into the inner surface of the bearing and configured to allow a lubricating medium to be supplied to the inner surface independently of the first and second sets of lubrication holes.

[0007] The bearing according to the present invention provides improved lubrication that can be adjusted as needed. The bearing can be placed in an oil bath, and as the propeller shaft rotates, lubrication holes supply lubricant to the inner surface of the bearing. Additional lubricant can be supplied via the lubrication inlet to areas requiring greater lubrication. The lubrication inlet also allows for cooling of the lubricant, allowing cooler lubricant to be supplied to specific areas of the bearing. Use of the lubrication inlet can be limited to certain operating conditions to minimize energy consumption by the lubrication system.

[0008] According to an embodiment of the present invention, the at least one lubrication inlet is arranged at a distance from the lubrication holes in the first and second groups of lubrication holes along the circumferential direction of the bearing. By arranging the lubrication inlet at a different height from the lubrication holes, it is easier to provide a separate lubrication channel for the lubrication inlet. However, the lubrication inlet may also be arranged at the same height as the lubrication holes.

[0009] According to an embodiment of the present invention, the at least one lubrication inlet includes a first lubrication inlet arranged on a first side of the bearing. The propeller shaft exerts a greater load on the lower half of the bearing. When the lubrication inlet is arranged on one side of the bearing, the lubrication inlet supplies additional lubricating oil to the lower half of the bearing in one direction of propeller shaft rotation.

[0010] According to an embodiment of the present invention, the first lubrication inlet opens into a recessed area on the inner surface of the bearing. The recessed area surrounding the lubrication inlet helps distribute the lubricating medium over the inner surface of the bearing. It also reduces the spread of the lubricating medium outside the recessed area in the axial direction of the bearing, thereby concentrating more lubricating medium on certain areas of the inner surface of the bearing.

[0011] According to an embodiment of the present invention, the length of the recessed area in the axial direction of the bearing is at most 50% of the length of the bearing inner surface. This helps to retain a larger amount of lubricating medium in certain areas of the bearing inner surface.

[0012] According to an embodiment of the present invention, at least one lubrication hole of the first set of lubrication holes opens into the same recessed area as the first lubrication inlet. This allows the lubrication hole to serve as a pressure relief hole for the lubrication medium supplied via the first lubrication inlet, which helps to avoid excessive pressure on the inner surface of the bearing.

[0013] According to an embodiment of the present invention, the first lubrication inlet opens into a first recessed area on the inner surface of the bearing. A second recessed area is provided on the first side of the bearing, the second recessed area being separated from the first recessed area by a wall, and at least one lubrication hole in the first set of lubrication holes opens into the second recessed area. The two separate recessed areas help retain a greater amount of lubricating medium in certain areas of the bearing.

[0014] According to an embodiment of the invention, the first lubrication inlet is arranged above the level of the lubrication holes of the first group of lubrication holes.

[0015] According to an embodiment of the present invention, a bearing includes a first lubricating medium supply hole extending into an end face of the bearing and a first lubrication channel connecting a first lubrication inlet to the first lubricating medium supply hole. This arrangement allows lubricating medium to be supplied to the first lubrication inlet via the end face of the bearing. The first lubrication channel may be a groove or an internal channel on the outer surface of the bearing.

[0016] According to an embodiment of the present invention, the at least one lubrication inlet includes a second lubrication inlet that coincides with the bottom of the bearing. Providing a lubrication inlet on the bottom of the bearing allows lubrication medium to be supplied below the propeller shaft. The lubrication medium supplied via the second lubrication inlet can be pressurized to exert a lifting force on the propeller shaft.

[0017] According to an embodiment of the present invention, the second lubrication inlet opens into a recessed area on the inner surface of the bearing.The recessed area surrounding the second lubrication inlet facilitates the diffusion of the lubricating medium.

[0018] According to an embodiment of the present invention, the bearing comprises a second lubricating medium supply hole leading to the end face of the bearing and a second lubricating channel connecting the second lubricating inlet to the second lubricating medium supply hole. This arrangement allows lubricating medium to be supplied to the second lubricating inlet via the end face of the bearing.

[0019] According to an embodiment of the present invention, the at least one lubrication inlet is located at a distance of 10% to 40% of the bearing length from one end of the bearing. Typically, the maximum load area of ​​a bearing is near the end of the bearing, and by arranging the lubrication inlet near one end of the bearing, more lubrication medium can be supplied to this area.

[0020] According to an embodiment of the present invention, the lubrication inlet is positioned closer to the rear end of the bearing. The rear end of a bearing is typically more heavily loaded than the arcuate end, so it may be beneficial to supply more lubricating medium to the rear end. However, in some applications and under certain operating conditions, the arcuate end may be more heavily loaded, and the bearing may therefore include a lubrication inlet at the arcuate end, or at both the rear end and the arcuate end.

[0021] According to an embodiment of the present invention, the lubrication holes in the first group of lubrication holes are arranged at the same level along the circumference of the bearing, and the lubrication holes in the second group of lubrication holes are arranged at the same level along the circumference of the bearing. Thus, the lubrication holes contribute to uniform lubrication of the bearing, while the lubrication inlets can enhance lubrication in certain areas.

[0022] According to an embodiment of the present invention, the lubrication holes in the first group of lubrication holes open into a first groove on the outer surface of the bearing whose longitudinal direction is parallel to the axial direction of the bearing, and the lubrication holes in the second group of lubrication holes open into a second groove on the outer surface of the bearing whose longitudinal direction is parallel to the axial direction of the bearing.

[0023] The tail pipe bearing device according to the present invention includes a tail pipe and the above-mentioned bearing disposed in the tail pipe.

[0024] The propulsion device according to the present invention includes the tail tube device as described above, a propeller shaft supported by a bearing, and a propeller attached to the propeller shaft.

[0025] According to an embodiment of the invention, the propulsion device comprises means for supplying pressurized lubrication medium to said at least one lubrication inlet.

[0026] According to an embodiment of the invention, the propulsion device comprises means for controlling the pressure and / or the amount of lubrication medium supplied to the at least one lubrication inlet. This allows optimizing the lubrication of the bearing under different operating conditions.

[0027] According to an embodiment of the invention, the propulsion device comprises means for cooling the lubrication medium supplied to the at least one lubrication inlet.The cooling device allows controlling the temperature of the most loaded area of ​​the bearing.

[0028] According to one embodiment of the present invention, a propulsion device includes at least one of the following: a temperature sensor for monitoring the temperature of the lubricating medium in the tail tube; a sensor for monitoring the thickness of the lubricating medium film in the bearing; and a rotational speed sensor for monitoring the rotational speed of the propeller shaft. By monitoring different parameters, bearing lubrication can be optimized under different operating conditions. The temperature sensor can be arranged to monitor the temperature of the lubricating medium in the bearing.

[0029] According to an embodiment of the invention, the propulsion device comprises a control unit configured to control the supply of lubrication medium via the at least one lubrication inlet based on the temperature of the lubrication medium in the tail tube, the thickness of the lubrication film in the bearing and / or the rotational speed of the propeller shaft.

[0030] A vessel according to the invention comprises a propulsion device as described above.

[0031] The method of operating a propulsion device as described above comprises the step of introducing lubrication medium onto the inner surface of the bearing via the at least one lubrication inlet.

[0032] According to an embodiment of the present invention, the method includes at least one operating mode in which lubricating medium is introduced to the inner surface of the bearing via both the lubrication holes and the at least one lubrication inlet; and at least one operating mode in which lubricating medium is introduced to the inner surface of the bearing via only the lubrication holes. Thus, lubrication of the bearing can be controlled as needed, with lubricating medium being supplied via the lubrication inlet or inlets only when required.

[0033] According to an embodiment of the invention, the bearing comprises a first lubrication inlet and a second lubrication inlet, and the method comprises: at least one operating mode in which the lubrication medium is supplied both via the lubrication hole and via the first lubrication inlet and the second lubrication inlet; at least one operating mode in which the lubrication medium is supplied only via the lubrication hole and the first lubrication inlet; and at least one operating mode in which the lubrication medium is supplied only via the lubrication hole and the second lubrication inlet.

[0034] According to an embodiment of the present invention, the lubricating medium is supplied via the second lubrication inlet at a higher pressure than via the first lubrication inlet. The higher pressure generates a lifting force on the propeller shaft. The pressure of the lubricating medium supplied via the second lubrication inlet can be, for example, at least 15 bar.

[0035] According to an embodiment of the present invention, the lubricating medium supplied via the first lubrication inlet is cooled before being supplied to the bearing. Cooling the lubricating medium helps maintain its temperature within a desired range. By cooling the lubricating medium supplied via the first lubrication inlet, it is not necessary to cool the high-pressure lubricating medium supplied via the second lubrication inlet, thus eliminating the need for a heat exchanger that can withstand high pressure.

[0036] According to an embodiment of the present invention, the method includes the steps of: monitoring at least one of the following parameters: the thickness of a lubricating film on an inner surface of the bearing, the rotational speed of the propeller shaft, and the temperature of the lubricating medium; and controlling the flow of lubricating medium through the at least one lubrication inlet based on the value of one or more of the monitored parameters. By monitoring one or more parameters, lubrication of the bearing can be optimized under all operating conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The embodiments of the present invention are described in more detail below with reference to the accompanying drawings, in which

[0038] Figure 1 shows a perspective rear view of a bearing according to an embodiment of the invention,

[0039] Figure 2 Shown Figure 1 Perspective front view of the bearing,

[0040] Figure 3Schematically shows a part of a ship and a propulsion device according to an embodiment of the present invention,

[0041] Figure 4 schematically shows further details of a propulsion arrangement according to an embodiment of the invention, and

[0042] Figure 5 A block diagram of a control system for a propulsion device is shown. DETAILED DESCRIPTION

[0043] Figure 1 and Figure 2 A bearing 1 according to an embodiment of the present invention is shown. Bearing 1 can be used to support a propeller shaft of a ship in a radial direction of the propeller shaft. The term "propeller shaft" herein refers to the shaft that connects the ship's propeller to the crankshaft of the ship's main engine. The main engine may be, for example, a two-stroke piston engine that can be driven in both directions of rotation to propel the ship both forward and aft. Bearing 1 may specifically be a stern tube bearing. The stern tube is a hollow tube located at the lower portion of the stern of a ship. The stern tube allows the propeller shaft to pass through the ship's hull.

[0044] Bearing 1 is configured to be mounted in a tailpipe in a specific orientation. One end face of bearing 1 is configured to face rearward, while the other end face of bearing 1 is configured to face forward. In the axial direction of bearing 1, bearing 1 thus has a front end (i.e., an arcuate end) and a rear end (i.e., a rearward end). Figure 1 The rear end of the bearing is shown, Figure 2 The bowed end of bearing 1 is shown. Bearing 1 is not rotationally symmetrical and is therefore configured to be installed in a specific rotational orientation. When installed, bearing 1 has a top, a bottom, a first side, and a second side. The first side extends from top to bottom in a first circumferential direction of bearing 1, and the second side extends from top to bottom in a second circumferential direction opposite the first circumferential direction. In the embodiment shown in the figures, the first side of bearing 1 is the port side of bearing 1, i.e., the side on the left-hand side when viewing bearing 1 from the rear of the vessel, and the second side of bearing 1 is the starboard side of bearing 1, i.e., the side on the right-hand side when viewing bearing 1 from the rear of the vessel. In the embodiment shown in the figures, when the propeller propels the vessel forward, the propeller shaft rotates counterclockwise as viewed from the rear of the vessel. Therefore, the first circumferential direction of bearing 1 is the same as the direction of propeller shaft rotation when the propeller propels the vessel forward. The propeller shaft rotates from the first side of bearing 1 through the bottom of bearing 1 to the second side. As the propeller moves the vessel forward, the point on the outer surface of the propeller shaft thus moves from top to bottom on a first side and then from bottom to top on a second side.

[0045] Bearing 1 has an outer surface, i.e., the outer circumferential surface, and an inner surface, i.e., the inner circumferential surface. The inner surface is the bearing surface against which the propeller shaft rotates. The shaft does not rotate directly against the bearing surface, but bearing 1 is configured to allow a lubricant to be supplied to the inner surface of bearing 1. The lubricant can be lubricating oil. The lubricating oil forms an oil film between the bearing surface and the propeller shaft. This prevents direct contact between the surfaces of bearing 1 and the propeller shaft, reducing friction between the surfaces.

[0046] In the embodiment of the figures, the bearing 1 is a one-piece component. However, the bearing 1 can also be made of two or more components. For example, the bearing 1 can be made of two or more pieces having the shape of a circle segment.

[0047] Bearing 1 includes a plurality of lubrication holes 2a, 2b, 2c, 4a, 4b, 4c extending from the outer surface of bearing 1 to the inner surface of bearing 1. Lubrication holes 2a, 2b, 2c, 4a, 4b, 4c allow lubrication medium to flow between the inner and outer surfaces. The lubrication holes include a first set of lubrication holes 2 opening into the inner surface of bearing 1 on a first side of bearing 1 and a second set of lubrication holes 4 opening into the inner surface of bearing 1 on a second side of bearing 1. In the embodiment shown in the accompanying drawings, lubrication holes 2a, 2b, 2c on the first side and lubrication holes 4a, 4b, 4c on the second side are arranged symmetrically about an imaginary vertical midplane dividing bearing 1 into the first and second sides. Therefore, lubrication of bearing 1 via lubrication holes 2a, 2b, 2c, 4a, 4b, 4c functions essentially the same way regardless of the direction of rotation of the propeller shaft. However, the lubrication holes do not necessarily need to be arranged symmetrically about the midplane.

[0048] In the embodiment of the figures, three lubrication holes 2a, 2b, 2c, 4a, 4b, 4c are arranged on each side of the bearing 1. However, the number of lubrication holes may also be different. Preferably, at least two lubrication holes 2a, 2b, 2c, 4a, 4b, 4c are arranged on each of the first and second sides to distribute the lubricating medium over the entire bearing surface.

[0049] In the embodiment shown in the accompanying drawings, the lubrication holes 2a, 2b, and 2c in the first group of lubrication holes 2 are arranged at the same horizontal height along the circumference of the bearing 1, and the lubrication holes 4a, 4b, and 4c in the second group of lubrication holes 4 are arranged at the same horizontal height along the circumference of the bearing 1. However, the lubrication holes may be arranged at different heights. In the embodiment shown in the accompanying drawings, the lubrication holes 2a, 2b, 2c, 4a, 4b, and 4c are arranged on both sides of the bearing 1, forming a horizontal midplane that divides the bearing 1 into a lower half and an upper half. However, the lubrication holes 2a, 2b, 2c, 4a, 4b, and 4c may also be arranged above the horizontal midplane. All lubrication holes 2a, 2b, 2c, 4a, 4b, and 4c may be at the same height. Alternatively, the lubrication holes 2a, 2b, and 2c on the first side may be arranged higher than the lubrication holes 4a, 4b, and 4c on the second side.

[0050] Lubrication holes 2a, 2b, 2c, 4a, 4b, 4c open into recessed areas 6a, 6b, 7 on the inner surface of bearing 1. Recessed areas 6a, 6b, 7 form oil pockets between bearing surface 1 and the propeller shaft. These oil pockets facilitate the spreading of the lubricant across the bearing surface. On the second side of the bearing, all lubrication holes 4a, 4b, 4c open into the same recessed area 7. Recessed area 7 on the second side of bearing 1 extends across the entire bearing surface in the axial direction of bearing 1. Recessed area 7 extends over an angle of approximately 30 degrees in the circumferential direction of bearing 1. Recessed area 7 can extend over an angle of, for example, 15 to 45 degrees. Recessed area 7 has transition zones on both sides along the circumferential direction of bearing 1, where the depth of recessed area 7 gradually changes.

[0051] On the first side of bearing 1, lubrication holes 2a, 2b, 2c open into two separate recessed areas 6a, 6b. One of lubrication holes 2a opens into first recessed area 6a, and two of lubrication holes 2b, 2c open into second recessed area 6b. In the circumferential direction, recessed areas 6a, 6b extend over the same angle as recessed area 7 on the second side of bearing 1.

[0052] Lubrication holes 2a, 2b, and 2c in the first group of lubrication holes 2 open into a first groove 3 on the outer surface of bearing 1, with the longitudinal direction of the first groove 3 being parallel to the axial direction of bearing 1. Thus, depending on the flow direction, the first groove 3 either supplies lubricating medium to or collects lubricating medium from the first group of lubrication holes 2. Similarly, lubrication holes 4a, 4b, and 4c in the second group of lubrication holes 4 open into a second groove 5 on the outer surface of bearing 1, with the longitudinal direction of the second groove 5 being parallel to the axial direction of bearing 1. Both the first groove 3 and the second groove 5 extend to both ends of bearing 1, allowing lubricating medium to flow along the entire outer surface of bearing 1 in the axial direction of bearing 1. Bearing 1 can be mounted in a tail pipe by press-fitting. The first and second grooves 4 and 5, together with the tail pipe, define a lubricating medium channel for the flow of lubricating medium. The outer surface of bearing 1 is provided with additional grooves 14, 15, 16, and 17.

[0053] The bearing 1 according to the present invention further includes at least one lubrication inlet 8, 11, which opens into the inner surface of the bearing 1 and is configured to allow lubrication medium to be supplied to the inner surface of the bearing 1 independently of the first and second sets of lubrication holes 2, 4. Thus, the lubrication inlets 8, 11 provide an additional way to introduce lubrication medium to the bearing surface. This allows for an increased amount of lubrication medium in areas requiring more lubrication.

[0054] In the embodiment shown in the accompanying drawings, bearing 1 includes a first lubrication inlet 8 arranged on a first side of bearing 1. Bearing 1 also includes a second lubrication inlet 11 that coincides with the bottom of bearing 1. However, bearing 1 may include only the first lubrication inlet 8 or only the second lubrication inlet 11. Bearing 1 may also include additional lubrication inlets. The first and second lubrication inlets 8 and 11 are arranged at a distance from the lubrication holes 2a, 2b, 2c, 4a, 4b, and 4c in the first and second groups of lubrication holes 2 and 4 in the circumferential direction of bearing 1. The first lubrication inlet 8 is arranged above the level of the lubrication holes 2a, 2b, and 2c in the first group of lubrication holes 2. By arranging the first lubrication inlet 8 at a different height than the lubrication holes 2a, 2b, and 2c, the first lubrication inlet 8 is not in fluid communication with the first groove 3 that supplies lubricating medium to the first group of lubrication holes 2. However, by arranging the lubricating medium supply to the first group of lubrication holes 2 and the first lubrication inlet 8 in a different manner, the first lubrication inlet 8 can also be arranged at the same height as the lubrication holes 2a, 2b, and 2c in the first group of lubrication holes 2. The first lubrication inlet 8 may also be arranged below the level of the lubrication holes 2 a , 2 b , 2 c of the first group of lubrication holes 2 .

[0055] As described above, in the embodiment shown in the accompanying drawings, the propeller shaft rotates from the first side of the bearing, via the bottom, to the second side. Therefore, when the propeller propels the vessel forward, bearing 1 can be effectively lubricated via first lubrication inlet 8. In most cases, the vessel only moves backward for brief periods. Therefore, less stringent requirements are imposed on lubrication in the reverse direction of the propeller shaft, and lubrication inlet 8 on the second side of bearing 1 is not required. However, a similar lubrication inlet 8 may also be provided on the second side.

[0056] In the embodiment shown in the accompanying drawings, the first lubrication inlet 8 opens into a first recessed area 6a on the inner surface of the bearing 1 on the first side of the bearing 1. Consequently, one of the lubrication holes 2a, 2b, or 2c opens into the same recessed area 6a. The first recessed area 6a and the second recessed area 6b are separated from each other. A wall 18 exists between the two recessed areas 6a and 6b, preventing direct flow between the two areas 6a and 6b. This ensures that the lubricating medium supplied via the first lubrication inlet 8 is not immediately dispersed over the entire bearing surface 1. Instead, the majority of the lubricating medium remains in the area surrounding the first lubrication inlet 8. In the embodiment shown in the accompanying drawings, the length of the first recessed area 6a in the axial direction of the bearing 1 is approximately one-third of the length of the inner surface of the bearing 1. The length of the first recessed area 6a is preferably no more than 50% of the bearing surface length. The lubrication hole 2a, which opens into the same recessed area 6a as the first lubrication inlet 18, serves as a pressure relief hole. This pressure relief hole helps prevent excessive pressure on the inner surface of the bearing 1.

[0057] In the embodiment shown in the accompanying drawings, the first lubrication inlet 8 is arranged closer to the rear end than to the arcuate end of the bearing 1. In the embodiment shown in the accompanying drawings, the distance between the first lubrication inlet 8 and the rear end is approximately 20% of the length of the bearing 1. The first lubrication inlet 8 can be located at a distance from the rear end that is between 10% and 40% of the length of the bearing 1. The rear end is typically loaded more heavily than the arcuate end, and therefore it is beneficial to arrange the first lubrication inlet closer to the rear end. However, under certain operating conditions, the arcuate end may be loaded more heavily, and the first lubrication inlet 8 can therefore also be arranged closer to the arcuate end. The bearing 1 can also be provided with lubrication inlets arranged at both the rear end and the arcuate end. Preferably, the supply of lubricating medium to the two lubrication inlets can be controlled independently of each other.

[0058] The first recessed area 6a does not extend to the end of the bearing surface, but a wall 19 is formed at the rear end of the first recessed area 6a. The wall 19 reduces the escape of lubricating medium from the recessed area 6a via the rear end of the bearing 1.

[0059] Bearing 1 includes a first lubricating medium supply hole 9 leading to an end face of bearing 1 and a first lubricating channel 10 connecting first lubricating inlet 8 to first lubricating medium supply hole 9. In the embodiment of the accompanying drawings, first lubricating channel 10 is a groove on the outer surface of bearing 1, and first lubricating medium supply hole 9 is arranged at the arcuate end of bearing 1. However, first lubricating channel 10 may also be arranged within the housing of bearing 1 and / or first lubricating medium supply hole 9 may be arranged at the rear end of bearing 1. Lubricating medium may also be supplied to first lubricating inlet 8 via a different arrangement, for example, via a pipe extending radially through the tail pipe.

[0060] Furthermore, the second lubrication inlet 11 opens into a recessed area 12 on the inner surface of the bearing 1. Apart from the second lubrication inlet 11, the recessed area 12 is not provided with any other holes.

[0061] The bearing 1 includes a second lubricating medium supply hole 13 leading to the end face of the bearing 1 and a second lubricating channel connecting the second lubricating inlet 11 to the second lubricating medium supply hole 13. Moreover, the second lubricating medium supply hole 13 is arranged at the arcuate end of the bearing 1, but may be arranged differently.

[0062] The second lubrication inlet 11 is arranged in the axial direction of the bearing at a distance of approximately 20% of the length of the bearing 1 from the rear end of the bearing 1. This distance may be, for example, in the range of 10%-40% of the length of the bearing 1.

[0063] As with the first lubrication inlet 8, by arranging the second lubrication inlet 11 close to the rear end of the bearing 1, additional lubrication can be provided to the area that is typically most loaded. The lubrication medium supplied via the second lubrication inlet 11 can be introduced onto the bearing surface at a higher pressure, thereby exerting a lifting force on the propeller shaft.

[0064] Figure 3 A propulsion device and a portion of a vessel 20 according to an embodiment of the invention are schematically shown. Figure 4 Further details of the propulsion device are shown. The vessel 20 is provided with a propeller 21. The propeller 21 is connected to a crankshaft 23 of a main engine 21 of the vessel 20 via a propeller shaft 22. The main engine 21 may be, for example, a two-stroke or four-stroke piston engine. The propeller shaft 22 passes through the hull 24 of the vessel 20 in a tail tube 25. The bearing 1 according to the invention is arranged at the rear end of the tail tube 25 to support the propeller shaft 22. Figure 3In the embodiment, another tail tube bearing 26 is arranged at the arcuate end of the tail tube 25. Bearing 26 at the arcuate end of the tail tube 25 can be similar to bearing 1 at the aft end of the tail tube 25. Bearings 1 and 26 can be installed in the tail tube 25 by press fit. Another bearing 27 is arranged between the tail tube 25 and the main engine 21 to support the propeller shaft 22. The number of bearings supporting the propeller shaft 22 can vary. It is also possible to arrange only one bearing in the tail tube 25, and the other bearings supporting the propeller shaft are external to the tail tube 25.

[0065] Tail tube 25 is filled with a lubricating medium, such as lubricating oil. As propeller shaft 22 rotates, the lubricating medium flows through lubrication holes 2a, 2b, 2c, 4a, 4b, and 4c of bearing 1, keeping bearing 1 lubricated. Seals 28 and 29 are provided at each end of tail tube 25. Seals 28 and 29 prevent water from entering tail tube 25 and prevent lubricating medium from escaping.

[0066] In order to improve the lubrication of the bearing 1, the propulsion device is provided with a lubrication pump 30. Figure 4 In the embodiment, two lubrication pumps 30 are provided for redundancy. If redundancy is not required, the propulsion device can be provided with a single lubrication pump 30. Each lubrication pump 30 is configured to supply lubricating medium to the bearing 1. The lubrication pump 30 also supplies lubricating medium to the seals 28 and 29, where the lubricating medium serves as sealing oil. However, a separate pump may be provided to supply lubricating medium to the seals 28 and 29.

[0067] The propulsion device includes a first supply line 31 for supplying lubricating medium from a lubrication pump 30 to the first lubrication inlet 8 of the bearing 1, and a second supply line 32 for supplying lubricating medium to the second lubrication inlet 11 of the bearing 1. A sealing medium supply line 33 is provided to supply lubricating medium to the sealing devices 28 and 29. A distribution block 40 and a pressure control block 41 are arranged between the lubrication pump 30 and the tail pipe 25. The distribution block 40 serves as a flow control device for controlling the amount of lubricating medium supplied to the bearing 1 and the sealing devices 28 and 29. The pressure control block 41 serves as a pressure control device for controlling the pressure of the lubricating medium supplied to the bearing 1 and the sealing devices 28 and 29.

[0068] The two separate supply lines 30, 31 and the flow control device 40 allow independent control of the amount of lubricating medium supplied via the first lubrication inlet 8 and the second lubrication inlet 11. The two separate supply lines 30, 31 and the pressure control device 41 allow independent control of the pressure of the lubricating medium supplied via the first lubrication inlet 8 and the second lubrication inlet 11.

[0069] The device is also provided with a return line 39 configured to supply excess lubricating medium from the tail pipe 25 back to the lubrication pump 30. A heat exchanger 34 is arranged in the first supply line 31. The heat exchanger 34 is configured to cool the lubricating medium supplied via the first lubrication inlet 8. The heat exchanger 34 allows the temperature of the bearing 1 arranged at the rear end of the tail pipe 25 to be controlled.

[0070] The pressure control device 41 can be configured to supply lubricating medium to the second lubricating inlet 11 at a higher pressure than that of the first lubricating inlet 8. The pressure of the lubricating medium supplied via the first lubricating inlet 8 can be, for example, in the range of 1-5 bar, more preferably 1-3 bar. The pressure of the lubricating medium supplied via the second lubricating inlet 11 can be, for example, in the range of 15-30 bar. However, the pressure of the lubricating medium supplied via the lubricating inlets 8 and 11 can exceed this range for a short period of time. For example, when the lubricating medium supply via the second lubricating inlet 11 begins, the surge pressure can be as high as 60-70 bar, from which the pressure quickly drops to the aforementioned range of 15-30 bar.

[0071] Figure 3 and Figure 4 The propulsion device further includes a rotational speed sensor 37 configured to monitor the rotational speed of the propeller shaft 22. The device further includes a temperature sensor 35 configured to monitor the temperature of the lubricating medium in the bearing 1. The device further includes an oil film thickness sensor 36 for monitoring the thickness of the lubricating medium film on the bearing surface of the bearing 1.

[0072] The amount and pressure of the lubricating medium supplied to the bearing 1 can be controlled in a number of alternative ways. For example, the propulsion device can be provided with separate pumps for supplying lubricating medium to the first lubrication inlet 8 and the second lubrication inlet 11. Furthermore, the amount and / or pressure of the lubricating medium can be controlled by the lubrication pump 30, in which case no separate flow control device and / or pressure control device is required.

[0073] The lubrication of the bearing 1 may be controlled based on the operating conditions of the propulsion device. Figure 5A block diagram of a control system for a propulsion device is shown. The control system includes a control unit 38 configured to control the operation of a lubrication pump 30. The control unit 38 also controls the operation of a distribution block 40 and a pressure control block 41 to control the flow rate and pressure of the lubricating medium. The control system is provided with a temperature sensor 35 configured to monitor the temperature of the lubricating medium. The temperature sensor 35 can be arranged in the bearing 1 or within the tail pipe 25. The control system can include two or more temperature sensors arranged in different locations. Preferably, at least one temperature sensor 35 is arranged approximately in the middle of the bearing 1 in the axial direction of the bearing 1. The control system is also provided with at least one sensor 36 for monitoring the thickness of the lubricating medium film on the bearing surface of the bearing 1. The oil film thickness sensor 36 can be arranged at the rear end of the bearing 1. This allows the oil film thickness at the rear end of the bearing 1 to be monitored. This is particularly beneficial when the first lubrication inlet 8 and / or the second lubrication inlet 11 are arranged near the rear end of the bearing 1, as the oil film thickness can be monitored in the area where the lubricating medium is supplied via the lubrication inlets 8 and 11. The control system is also provided with a rotational speed sensor 37, which is configured to monitor the rotational speed of the propeller shaft 22. A control unit 38 receives measurement data from the temperature sensor 35, the oil film thickness sensor 36, and the rotational speed sensor 37. Instead of the rotational speed sensor 37, the control unit 38 may receive rotational speed data from the engine 21. The functionality of the sensors 35, 36, and 37 may also be integrated into one or more multifunctional sensors configured to monitor two or more different parameters.

[0074] Control unit 38 is configured to control operations of lubrication pump 30 , flow control device 40 , and pressure control device 41 based on the temperature of the lubrication medium, the thickness of the lubrication medium film, and / or the rotational speed of propeller shaft 22 .

[0075] Depending on the values ​​of various control parameters, such as lubricant temperature, oil film thickness, and the rotational speed of the propeller shaft 22, the propulsion device can be operated in different operating modes. To select an operating mode, the lubricant temperature and / or lubricant film thickness can be compared to corresponding target ranges or one or more threshold values. Furthermore, the rotational speed of the propeller shaft 22 can be compared to one or more threshold values.

[0076] According to an embodiment of the present invention, the propulsion device can operate in at least four different operating modes. When the tail pipe 25 is filled with lubricating medium, in all operating modes, at least a portion of the lubricating medium flows through the lubrication holes 2a, 2b, 2c, 4a, 4b, 4c of the bearing 1. In the first operating mode, the lubricating medium is also supplied through the first lubrication inlet 8. In the second operating mode, the lubricating medium is supplied through the second lubrication inlet 11. In the third operating mode, the lubricating medium is supplied through both the first lubrication inlet 8 and the second lubrication inlet 11. In the fourth operating mode, the lubricating medium is supplied only through the lubrication holes 2a, 2b, 2c, 4a, 4b, 4c.

[0077] The first operating mode is a normal operating mode that can be used under most operating conditions.

[0078] In particular, the second operating mode can be used when the rotational speed of the propeller shaft 22 is low, for example, below a threshold value. The second operating mode is also beneficial when the temperature of the lubricating medium is low (for example, below a target range or below a first threshold value) and the thickness of the lubricating medium film is low (for example, below a first threshold value).

[0079] The third operating mode may be used when the temperature of the lubricating medium is high, for example above the target range or above the second threshold, and the thickness of the lubricating medium film is low, for example below the first threshold.

[0080] The fourth operating mode can be used when the temperature of the lubricating medium is relatively low, for example, below the second threshold and the thickness of the lubricating medium is within the desired range or above the first threshold or the second threshold. The fourth operating mode also serves as an emergency mode if the lubrication pump 30 fails and other operating modes are unavailable.

[0081] As an example, a target range for the lubricating medium temperature is determined. The lower limit of the target range may be, for example, 20°C. The upper limit of the target range may be, for example, 50°C. Furthermore, a threshold value for the lubricating medium temperature may be determined. The threshold value may be within the target range. As an example, the threshold value may be 45°C.

[0082] A threshold value may be determined for the rotational speed of the propeller shaft 22. The threshold value may be a certain percentage of the maximum continuous speed of the propeller shaft 22, ie a certain percentage of the nominal rotational speed of the propeller shaft 22. As an example, the threshold value may be 25% of the nominal speed.

[0083] A first threshold value for the thickness of the lubricating film may be determined. As an example, the first threshold value may be 50 μm. A second threshold value for the thickness of the lubricating film may also be determined. The second threshold value may be greater than the first threshold value, for example, 60 μm.

[0084] The operating mode can be selected by comparing the monitored parameters to corresponding target ranges or thresholds. The first operating mode provides cooling of the lubricating medium. The second operating mode provides damping and support for the propeller shaft 22. The third operating mode provides cooling, damping, and support. The fourth operating mode provides energy savings.

[0085] The first operating mode may be used when the rotational speed of the propeller shaft 22 is above a corresponding threshold, the thickness of the lubricating medium film is above a corresponding first threshold, and the temperature of the lubricating medium is within or above a corresponding target range.

[0086] The second operating mode may be used when the rotational speed of the propeller shaft 22 is below a corresponding threshold value and / or the thickness of the lubricating medium is below a corresponding first threshold value and the temperature of the lubricating medium is below a corresponding target range.

[0087] The third operating mode may be used when the temperature of the lubricating medium is above a respective target range and the thickness of the lubricating medium film is below a respective first threshold value.

[0088] The fourth operating mode can be used when the thickness of the lubricating medium film is above a respective second threshold value and the temperature of the lubricating medium is below a respective second threshold value.

[0089] In an operating mode that includes supplying lubricating medium via the first lubrication inlet 8 and / or the second lubrication inlet 11, the pressure and / or flow rate of the lubricating medium can be adjusted to more accurately meet lubrication requirements. Furthermore, the temperature of the lubricating medium supplied via the first lubrication inlet 8 can be controlled, for example by providing a first supply line 31 between the lubrication pump 30 and the bearing 1, having a bypass line that allows bypassing the heat exchanger 34. Alternatively or additionally, the flow rate and / or temperature of the heat exchange medium flowing through the heat exchanger 34 can be controlled to control the temperature of the lubricating medium.

Claims

1. A bearing (1) for radially supporting a propeller shaft (22) of a vessel (20), the bearing (1) being configured to be installed in a stern tube (25) of the vessel (20), and having, when installed: -top, -bottom, - a first side extending from the top to the bottom in a first circumferential direction of the bearing (1); and - a second side extending from the top to the bottom in a second circumferential direction opposite to the first circumferential direction, The bearing (1) comprises a plurality of lubrication holes (2a, 2b, 2c, 4a, 4b, 4c) extending from an outer surface of the bearing (1) to an inner surface of the bearing (1) to allow a lubricating medium to flow between the inner surface and the outer surface, the lubrication holes (2a, 2b, 2c, 4a, 4b, 4c) comprising a first group of lubrication holes (2) opening to the inner surface of the bearing (1) on a first side of the bearing (1) and a second group of lubrication holes (4) opening to the inner surface of the bearing (1) on a second side of the bearing (1), It is characterized by: The bearing (1) further comprises at least one lubrication inlet (8, 11) which opens onto the inner surface of the bearing (1) and is configured to allow lubrication medium to be supplied to the inner surface independently of the first set of lubrication holes (2) and the second set of lubrication holes (4).

2. The bearing (1) according to claim 1, wherein The at least one lubrication inlet (8, 11) is arranged at a distance from the lubrication holes (2a, 2b, 2c, 4a, 4b, 4c) of the first group of lubrication holes (2) and the second group of lubrication holes (4) in the circumferential direction of the bearing (1).

3. The bearing (1) according to claim 1 or 2, wherein: The at least one lubrication inlet (8, 11) comprises a first lubrication inlet (8) arranged on a first side of the bearing (1).

4. The bearing (1) according to claim 3, wherein: The first lubrication inlet (8) opens into a recessed area (6a) on the inner surface of the bearing (1).

5. The bearing (1) according to claim 4, wherein The length of the recessed area (6a) in the axial direction of the bearing (1) is at most 50% of the length of the inner surface of the bearing (1).

6. The bearing (1) according to claim 5, wherein At least one of the lubrication holes (2a, 2b, 2c) of the first group of lubrication holes (2) opens into the same recessed area (6a) as the first lubrication inlet (8).

7. The bearing (1) according to any one of claims 4 to 6, wherein: The first lubrication inlet (8) opens into a first recessed area (6a) on the inner surface of the bearing (1), the first side of the bearing (1) is provided with a second recessed area (6b), the second recessed area (6b) being separated from the first recessed area (6a) by a wall (18), and at least one of the lubrication holes (2a, 2b, 2c) in the first group of lubrication holes (2) opens into the second recessed area (6b).

8. The bearing (1) according to any one of claims 3 to 7, wherein: The first lubrication inlet (8) is arranged above the level of the lubrication holes (2a, 2b, 2c) of the first group of lubrication holes (2).

9. The bearing (1) according to any one of claims 3 to 8, wherein: The bearing (1) comprises a first lubricating medium supply hole (9) leading to an end face of the bearing (1) and a first lubricating channel (10) connecting the first lubricating inlet (8) to the first lubricating medium supply hole (9).

10. Bearing (1) according to any one of the preceding claims, wherein The at least one lubrication inlet (8, 11) includes a second lubrication inlet (11) coinciding with the bottom of the bearing (1).

11. The bearing (1) according to claim 10, wherein The second lubrication inlet (11) opens into a recessed area (12) on the inner surface of the bearing (1).

12. The bearing (1) according to claim 10 or 11, wherein: The bearing (1) comprises a second lubricating medium supply hole (13) leading to an end surface of the bearing (1) and a second lubricating passage connecting the second lubricating inlet (11) to the second lubricating medium supply hole (13).

13. Bearing (1) according to any one of the preceding claims, wherein The at least one lubrication inlet (8, 11) is positioned at a distance from one end of the bearing (1) of 10% to 40% of the length of the bearing (1).

14. The bearing (1) according to claim 13, wherein The lubrication inlets (8, 11) are located closer to the rear end of the bearing (1).

15. Bearing (1) according to any one of the preceding claims, wherein The lubrication holes (2a, 2b, 2c) in the first group of lubrication holes (2) are arranged at the same level as one another in the circumferential direction of the bearing (1), and the lubrication holes (4a, 4b, 4c) in the second group of lubrication holes (4) are arranged at the same level as one another in the circumferential direction of the bearing (1).

16. Bearing (1) according to any one of the preceding claims, wherein The lubrication holes (2a, 2b, 2c) in the first group of lubrication holes (2) open into a first groove (3) on the outer surface of the bearing (1) whose longitudinal direction is parallel to the axial direction of the bearing (1), and the lubrication holes (4a, 4b, 4c) in the second group of lubrication holes (4) open into a second groove (5) on the outer surface of the bearing (1) whose longitudinal direction is parallel to the axial direction of the bearing (1).

17. A stern tube bearing arrangement for a vessel (20), the arrangement comprising a stern tube (25) and a bearing (1) according to any one of the preceding claims arranged in the stern tube (25).

18. A propulsion device for a ship (20), comprising the stern tube device according to claim 17, a propeller shaft (22) supported by the bearing (1), and a propeller (21) attached to the propeller shaft (22).

19. The propulsion device according to claim 18, wherein: The device comprises means (30, 31, 32) for supplying pressurized lubrication medium to the at least one lubrication inlet (8, 11).

20. The propulsion device according to claim 19, wherein: The device comprises means (40, 41) for controlling the pressure and / or the amount of lubrication medium supplied to the at least one lubrication inlet (8, 11).

21. A propulsion device according to claim 19 or 20, wherein: The device comprises means (34) for cooling the lubrication medium supplied to the at least one lubrication inlet (8, 11).

22. A propulsion device according to any one of claims 18 to 21, wherein: The device comprises at least one of the following: a temperature sensor (35) for monitoring the temperature of the lubricating medium in the tail pipe (25); a sensor (36) for monitoring the thickness of the lubricating medium film in the bearing (1); and a rotational speed sensor (37) for monitoring the rotational speed of the propeller shaft (22).

23. The propulsion device according to claim 22, wherein: The device comprises a control unit (38) configured to control the supply of lubricating medium via the at least one lubricating inlet (8, 11) based on the temperature of the lubricating medium in the tail pipe (25), the thickness of the lubricating medium film in the bearing (1) and / or the rotational speed of the propeller shaft (22).

24. A vessel (20) comprising a propulsion device according to any one of claims 18 to 23.

25. A method of operating a propulsion device according to any one of claims 18 to 23, wherein: The method comprises the step of introducing a lubricating medium onto the inner surface of the bearing (1) via the at least one lubrication inlet (8, 11).

26. The method according to claim 25, wherein The method comprises: at least one operating mode in which the lubricating medium is introduced onto the inner surface of the bearing (1) both via the lubrication holes (2a, 2b, 2c, 4a, 4b, 4c) and via the at least one lubrication inlet (8, 11); and at least one operating mode in which the lubricating medium is introduced onto the inner surface of the bearing (1) only via the lubrication holes (2a, 2b, 2c, 4a, 4b, 4c).

27. The method according to claim 25 or 26, wherein The bearing (1) is a bearing according to any one of claims 3 to 9 and 10 to 12, and the method comprises: at least one operating mode in which the lubricating medium is supplied both via the lubrication holes (2a, 2b, 2c, 4a, 4b, 4c) and via the first lubrication inlet (8) and the second lubrication inlet (11); at least one operating mode in which the lubricating medium is supplied only via the lubrication holes (2a, 2b, 2c, 4a, 4b, 4c) and the first lubrication inlet (8); and at least one operating mode in which the lubricating medium is supplied only via the lubrication holes (2a, 2b, 2c, 4a, 4b, 4c) and the second lubrication inlet (11).

28. The method according to claim 27, wherein The lubricating medium is supplied via the second lubricating inlet (11) at a higher pressure than via the first lubricating inlet (8).

29. The method according to claim 28, wherein The pressure of the lubrication medium supplied via the second lubrication inlet (11) is at least 15 bar.

30. The method according to any one of claims 27 to 29, wherein The lubrication medium supplied via the first lubrication inlet (8) is cooled before being supplied to the bearing (1).

31. The method according to any one of claims 25 to 30, wherein The method comprises the following steps: monitoring at least one of the following parameters: the thickness of the lubricating medium film on the inner surface of the bearing (1), the rotational speed of the propeller shaft (22), and the temperature of the lubricating medium; and The flow of lubrication medium through the at least one lubrication inlet (8, 11) is controlled based on the value of one or more of the monitored parameters.

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