Journal bearing

Abstract

To stably form an oil film over the whole periphery.SOLUTION: A journal bearing includes five pads, and five lubricating oil supply parts each having a supply nozzle for supplying a lubricating oil to a space between a pad surface and an outer peripheral surface of a rotor. The supply nozzle is arranged between pads adjacent in a rotation direction of the rotor, the five pads include an upper pad located above in a vertical direction with respect to an axis line and a lower pad located below in the vertical direction with respect to the axis line, the five supply nozzles include upper supply nozzles arranged side by side behind the rotation direction with respect to the upper pad, and lower supply nozzles arranged side by side behind in the rotation direction with respect to the lower pad, and the upper supply nozzles supply the lubricating oil more than the lower supply nozzles between the pad surface and the outer peripheral surface of the rotor.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to journal bearings. [Background Art]

[0002] For example, a rotating machine including a gas turbine, a steam turbine, and a centrifugal compressor includes a rotor that rotates about an axis, and a casing that surrounds the rotor from the outside. The rotor is rotatably supported by a bearing device. As such bearing devices, journal bearings that support radial loads of the rotor and thrust bearings that support axial loads of the rotor are widely used. As a journal bearing, a tilting pad bearing including a plurality of pads is known.

[0003] For example, Patent Document 1 discloses a tilting pad journal bearing device including a rotor, a plurality of bearing pads, a bearing housing that supports the plurality of bearing pads, and a supply unit that supplies lubricant to a gap between the rotor and the bearing pads. The lubricating oil supplied from the supply unit forms a lubricant film (oil film) between the rotor and the plurality of bearing pads, and the rotor is supported via the lubricant film. Furthermore, in the tilting pad journal bearing device of Patent Document 1, the amount of lubricant supplied to a bearing pad positioned adjacent downstream in the rotational direction of the rotor with respect to the maximum load bearing pad, which is the bearing pad that receives the largest load from the supported rotor among the bearing pads, is made larger than the amount of lubricant supplied to other bearing pads. [Prior Art Documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Unexamined Patent Publication No. 2017-141882 [Summary of the Invention] [Problem to be Solved by the Invention]

[0005] Incidentally, in journal bearings with multiple pads as described above, the load from the rotor centered on the axis acts most significantly on the pads positioned vertically below the rotor. As a result, the gap between the pad and the rotor becomes smaller for the pads positioned vertically below the rotor. On the other hand, the gap between the pad and the rotor becomes larger for the pads positioned vertically above the rotor. In particular, if the load from the rotor is very large and the gap between the pad and the rotor becomes too large, the amount of lubricating oil may be insufficient relative to the size of the gap between the pad and the rotor, and the oil film may not form properly. Therefore, it is required that the oil film be stably formed around the entire circumference even when subjected to a large load from the rotor.

[0006] This disclosure was made to solve the above problems and aims to provide a journal bearing capable of stably forming an oil film over its entire circumference. [Means for solving the problem]

[0007] To solve the above problems, the journal bearing according to the present disclosure comprises five pads having pad surfaces that slide against and support the outer circumferential surface of a rotor that rotates around an axis; a housing formed in an annular shape around the axis so as to cover the five pads; and five lubrication supply units, each having a supply nozzle that supplies lubricating oil between the pad surfaces and the outer circumferential surface of the rotor from outside the housing, wherein the supply nozzles are arranged between adjacent pads in the rotational direction of the rotor, and the five pads include an upper pad located above in the vertical direction with respect to the axis and a lower pad located below in the vertical direction with respect to the axis, and the five supply nozzles include an upper supply nozzle arranged behind the upper pad in the rotational direction and a lower supply nozzle arranged behind the lower pad in the rotational direction, wherein the upper supply nozzles supply more lubricating oil between the pad surfaces and the outer circumferential surface of the rotor than the lower supply nozzles. [Effects of the Invention]

[0008] According to the journal bearing of this disclosure, an oil film can be stably formed over the entire circumference. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic diagram showing the configuration of a centrifugal compressor according to an embodiment of the present invention. [Figure 2] This is a cross-sectional view perpendicular to the central axis of the journal bearing provided in the centrifugal compressor of the first embodiment. [Figure 3] This is a cross-sectional view perpendicular to the central axis of the journal bearing provided in the centrifugal compressor of the second embodiment. [Modes for carrying out the invention]

[0010] The following describes embodiments for carrying out the journal bearing and rotating machine according to the present invention with reference to the attached drawings. However, the present invention is not limited to these embodiments.

[0011] (Configuration of a rotating machine) A rotating machine is a machine in which a rotor 1 is rotatable relative to a casing 3 by journal bearings. Examples of rotating machines include compressors, turbines, motors, and pumps. In this embodiment, as an example, a single-shaft multi-stage centrifugal compressor 10 will be used as an example of a rotating machine. As shown in Figure 1, the centrifugal compressor (rotating machine) 10 of this embodiment mainly comprises a rotor 1, a casing 3, and a bearing section 5.

[0012] (Rotor configuration) The rotor 1 is rotatable within the casing 3 about axis O. The rotor 1 comprises a rotor body 11 and an impeller 12. The rotor body 11 extends axially in the direction Da about axis O. The rotor body 11 is supported by a bearing 5 in the casing 3 so as to be rotatable about axis O.

[0013] In the following, the direction in which the axis O extends is defined as the axial direction Da. The direction perpendicular to the axial direction Da is defined as the vertical direction Dv. In other words, the plane perpendicular to the vertical direction Dv is the horizontal plane. The axial direction Da of the rotor body 11 is aligned with the horizontal plane. In other words, the axis O extends horizontally. The radial direction relative to the axis O is simply defined as the radial direction Dr. Also, the direction around the rotor 1 with the axis O as the center is defined as the circumferential direction Dc. Furthermore, in the circumferential direction Dc, the direction in which the rotor 1 rotates is the rotational direction R. In the rotational direction R, the direction ahead of rotation, which is one side of the circumferential direction Dc, is the front of the rotational direction R, and the opposite side of the circumferential direction Dc relative to the front, which is the other side of the circumferential direction Dc, is the rear of the rotational direction R.

[0014] Multiple impellers 12 are arranged at intervals in the axial direction Da. Each impeller 12 is fixed to the rotor body 11. Each impeller 12 is rotatable integrally with the rotor body 11 around axis O. In this embodiment, for example, a total of six impellers 12 are provided.

[0015] The number of impellers 12 provided on the rotor body 11 and the orientation of the impellers 12 are not limited to those exemplified above and can be changed as appropriate.

[0016] (Casing configuration) The casing 3 is cylindrical in shape, extending in the axial direction Da with axis O as its center. The casing 3 has a suction port 31 for introducing working fluid into the casing 3 and a discharge port 32 for discharging the working fluid from the casing 3 to the outside.

[0017] (Bearing structure) The bearing section 5 rotatably supports the rotor body 11 around the axis O. The bearing section 5 is located inside the casing 3. The bearing section 5 includes a thrust bearing 51 and a journal bearing 6.

[0018] The thrust bearing 51 receives an axial load Da acting on the rotor body 11. The thrust bearing 51 is arranged at a position closer to the end of the rotor body 11 relative to the journal bearing 6.

[0019] The journal bearing 6 supports the rotor body 11 at a position closer to the end of the rotor body 11 in the axial direction Da with respect to the plurality of impellers 12. The journal bearing 6 receives a radial load Dr acting on the rotor body 11. A pair of the journal bearings 6 are arranged in the axial direction Da so as to sandwich the plurality of impellers 12. The journal bearing 6 of the present embodiment is a tilting pad bearing having a plurality of pads 62. As shown in FIG. 2, the journal bearing 6 of the present embodiment includes a housing 61, a pad 62, a support portion 63, and a lubricating oil supply portion 64.

[0020] The housing 61 is formed in an annular shape centered on the axis O so as to cover the five pads 62. The housing 61 covers all the pads 62 and the support portions 63. The housing 61 swingably supports the pads 62 from the outer side in the radial direction Dr via the support portions 63. The housing 61 is configured to be attachable to and detachable from the casing 3. A pipe (not shown) that sends lubricating oil supplied from an external supply source to the lubricating oil supply portion 64 is connected to the housing 61.

[0021] Five pads 62 are arranged on the inner side in the radial direction Dr relative to the inner circumferential surface of the housing 61, spaced apart from each other in the circumferential direction Dc. In the present embodiment, only five pads 62 are arranged at equal intervals in the circumferential direction Dc. When viewed from the axial direction Da, none of the five pads 62 is arranged directly below the axis O in the vertical direction Dv. In other words, the journal bearing 6 of the present embodiment is of a load between pad (LBP) type in which the load of the rotor 1 is uniformly supported mainly by two pads 62.

[0022] Each pad 62 has an arc shape in a cross-sectional view perpendicular to the axis O of the rotor 1, and a wide, curved plate shape in the circumferential direction Dc. The pad 62 has a pad surface 621 facing inward in the radial direction Dr, and a pad back surface 622 facing outward in the radial direction Dr.

[0023] The pad surface 621 is capable of sliding against the outer circumferential surface 1F of the rotor body 11. The pad surface 621 faces the outer circumferential surface 1F of the rotor body 11 in the radial direction Dr. When viewed from the axial direction Da, the pad surface 621 is curved so as to be concave toward the outside in the radial direction Dr. The radius of curvature of the pad surface 621 is set to be the same as, or slightly larger than, the radius of curvature of the outer circumferential surface 1F of the rotor body 11. Lubricating oil is supplied from the lubricating oil supply unit 64, and the lubricating oil intervenes between the pad surface 621 and the outer circumferential surface 1F of the rotating shaft, forming a film.

[0024] The back surface 622 of the pad is the surface facing outward in the radial direction Dr on the pad 62. In other words, the back surface 622 faces the opposite direction from the pad surface 621 in the radial direction Dr. When viewed from the axial direction Da, the back surface 622 of the pad is curved so as to be convex outward in the radial direction Dr. The central part of the back surface 622 in the circumferential direction Dc is supported by the support portion 63.

[0025] The support portion 63 pivotably supports the pad 62 relative to the housing 61. When viewed from the circumferential direction Dc, the support portion 63 is positioned between the housing 61 and the pad 62 in the radial direction Dr. Five support portions 63 are arranged at intervals in the circumferential direction Dc, with one support portion for each pad 62.

[0026] Furthermore, the five pads 62 of this embodiment include a plurality of upper pads 70 located above the vertical direction Dv with respect to the axis O, and a plurality of lower pads 75 located below the vertical direction Dv with respect to the axis O.

[0027] When viewed from the axial direction Da, more than half of the upper pad 70 is located above the vertical direction Dv with respect to the horizontal plane passing through the axis O. In this embodiment, three of the five pads 62 are designated as upper pads 70. Furthermore, the multiple upper pads 70 include a first distal pad 71 and a second distal pad 72.

[0028] The first distal pad 71 is positioned furthest from the point of greatest load received by the rotor 1 in the rotational direction R. One or two of the five pads 62 are positioned as the first distal pad 71. In this embodiment, the first distal pad 71 is only one of the pads 62 that is located directly above the axis O in the vertical direction Dv when viewed from the axial direction Da.

[0029] Here, the load point is the point among the multiple pads 62 that receive a load from the rotor 1 that receives the greatest load from the rotor 1, when viewed from the axial direction Da. In this embodiment, the load point is a point directly below the vertical direction Dv with respect to the axis O. However, the load point is not limited to being directly below the vertical direction Dv with respect to the axis O, but may be at a slightly inclined position (for example, in the range of +45° to -45°). In other words, the load point does not have to be a point on a perpendicular line that is perpendicular to the horizontal line and passes through the axis O when viewed from the axial direction Da. Therefore, the load point may be a point on a virtual inclined line that is inclined with respect to the perpendicular line and passes through the axis O when viewed from the axial direction Da.

[0030] The second distal pad 72 is the pad 62 closest to the first distal pad 71 in the rotational direction R. Two of the five pads 62 are positioned as the second distal pad 72. In this embodiment, the second distal pad 72 is one of the two pads 62 adjacent to the single first distal pad 71 in the rotational direction R when viewed from the axial direction Da. In other words, the upper pad 70 in this embodiment consists of only one first distal pad 71 and two second distal pads 72.

[0031] When viewed from the axial direction Da, more than half of the area of ​​the lower pad 75 is located below the horizontal plane passing through the axis O in the vertical direction Dv. In this embodiment, two of the five pads 62 are designated as the upper pads 70.

[0032] The lubrication oil supply unit 64 is capable of supplying lubricating oil between the pad surface 621 and the outer peripheral surface 1F of the rotor 1 from outside the housing 61. The lubrication oil supply unit 64 is connected to piping (not shown) connected to the housing 61. This allows the lubrication oil supply unit 64 to supply lubricating oil supplied from an external source to the journal bearing 6. The lubrication oil supply unit 64 supplies lubricating oil from the outside into the housing 61 during starting and stopping (such as when starting a rotating machine) when the rotor 1 is completely stopped, and during rated operation of a rotating machine when the rotor 1 is continuously rotating at high speed. The lubrication oil supply unit 64 in this embodiment has five supply nozzles 641.

[0033] The supply nozzle 641 sprays lubricating oil between the pad surface 621 and the outer circumferential surface 1F of the rotor 1. The supply nozzle 641 sprays lubricating oil toward the outer circumferential surface 1F of the rotor 1. The supply nozzle 641 is positioned between adjacent pads 62 in the circumferential direction Dc. The supply nozzle 641 is fixed to the housing 61. An oil supply hole 645 is formed at the tip of the supply nozzle 641, which is the innermost part in the radial direction Dr.

[0034] Furthermore, the five supply nozzles 641 of this embodiment include an upper supply nozzle 80 arranged in a line behind the upper pad 70 in the rotational direction R, and a lower supply nozzle 85 arranged in a line behind the lower pad 75 in the rotational direction R.

[0035] The number of upward supply nozzles 80 is the same as the number of upward pads 70. In this embodiment, three of the five supply nozzles 641 on the pads 62 are designated as upward supply nozzles 80. The upward supply nozzles 80 are capable of supplying more lubricating oil between the pad surface 621 and the outer peripheral surface 1F of the rotor 1 than the downward supply nozzles 85. In this embodiment, the oil supply holes 645 of the upward supply nozzles 80 are formed to be larger than the oil supply holes 645 of the downward supply nozzles 85. Furthermore, the multiple upward supply nozzles 80 include a first distal nozzle 81 and a second distal nozzle 82.

[0036] The first distal nozzle 81 is part of the upward supply nozzle 80. The first distal nozzle 81 is positioned behind the first distal pad 71 in the rotational direction R. The first distal nozzle 81 supplies the largest amount of lubricating oil between the pad surface 621 and the outer peripheral surface 1F of the rotor 1 among the five supply nozzles 641. The same number of first distal nozzles 81 are arranged as the number of first distal pads 71. In this embodiment, there is only one first distal nozzle 81. The first distal nozzle 81 is capable of supplying, for example, twice the amount of lubricating oil supplied from the downward supply nozzle 85 to the outer peripheral surface 1F of the rotor 1. In other words, the area of ​​the supply hole of the first distal nozzle 81 is twice the area of ​​the supply hole of the downward supply nozzle 85.

[0037] (Effects and Benefits) In the journal bearing 6 configured as described above, lubricating oil is supplied between the five pad surfaces 621 and the outer circumferential surface 1F of the rotor 1 by five supply nozzles 641. As a result, an oil film is formed between the five pad surfaces 621 and the outer circumferential surface 1F of the rotor 1. Here, the five pads 62 receive the largest load from the rotor 1 at the load point from the rotation axis. That is, the load point is where the largest load from the rotor 1 is applied directly below the vertical direction Dv with respect to the axis O when viewed from the axial direction Da. As a result, the size of the radial gap Dr between the five pad surfaces 621 and the outer circumferential surface 1F of the rotor body 11 is non-uniform in the rotation direction R (circumferential direction Dc), such that the gap below the vertical direction Dv is small and the gap above the vertical direction Dv is large. Specifically, the radial gap Dr between the five pad surfaces 621 and the outer peripheral surface 1F of the rotor 1 is narrower in the circumferential direction Dc as it approaches directly below the vertical direction Dv with respect to the axis O, and wider as it approaches directly above the vertical direction Dv with respect to the axis O.

[0038] In contrast, in the journal bearing 6 of this embodiment, the upper supply nozzle 80 supplies more lubricating oil than the lower supply nozzle 85. Therefore, more lubricating oil can be supplied to the gap above the vertical direction Dv where the upper pad 70 is positioned and the gap is wider, compared to the position where the lower pad 75 is positioned. Consequently, in the gap above the vertical direction Dv where the gap is wider, poor oil film formation due to insufficient lubricating oil is suppressed, and a stable oil film can be formed. As a result, even when subjected to a large load from the rotor 1, a stable oil film can be formed around the entire circumference.

[0039] Furthermore, in this embodiment, the first distal nozzle 81, which supplies lubricating oil from the rear in the rotational direction R to the first distal pad 71 located at the position furthest from the load point in the rotational direction R, supplies the most lubricating oil among the five supply nozzles 641. Therefore, in the rotational direction R, the most lubricating oil can be supplied to the gap directly above the axis O in the vertical direction Dv, where the gap is widest and opposite the load point. Consequently, in the region with the largest gap at the position opposite the load point in the rotational direction R, poor oil film formation due to insufficient lubricating oil can be suppressed with high precision, and an oil film can be stably formed. As a result, even when subjected to a large load from the rotor 1, an oil film can be stably formed with high precision around the entire circumference.

[0040] <Second Embodiment> Next, a second embodiment of the journal bearing 6A according to this disclosure will be described. In the journal bearing 6A described below, components common to the first embodiment are denoted by the same reference numerals in the figures and their descriptions are omitted.

[0041] (Journal bearing configuration) As shown in Figure 3, the configuration of the five supply nozzles 641A in the journal bearing 6A of the second embodiment differs from that of the first embodiment. In addition to the first distal nozzle 81, the five supply nozzles 641A of the second embodiment have a second distal nozzle 82.

[0042] The second distal nozzle 82 is part of the upward supply nozzle 80. The second distal nozzle 82 is positioned behind the second distal pad 72 in the rotational direction R. The second distal nozzle 82 supplies the same amount of lubricating oil as the first distal nozzle 81, or less than the amount supplied by the first distal nozzle 81, between the pad surface 621 and the outer peripheral surface 1F of the rotor 1. The same number of second distal nozzles 82 as the second distal pad 72 are arranged. In this embodiment, there are only two second distal nozzles 82. The second distal nozzle 82 is capable of supplying, for example, 1.5 times the amount of lubricating oil supplied from the downward supply nozzle 85 to the outer peripheral surface 1F of the rotor 1. In other words, the area of ​​the supply hole of the first distal nozzle 81 is twice the area of ​​the supply hole of the downward supply nozzle 85.

[0043] (Effects and Benefits) In the journal bearing 6A with the above configuration, a second distal nozzle 82 is provided to supply lubricating oil to the second distal pad 72, which is closest to the first distal pad 71 in the rotational direction R. This second distal nozzle 82 supplies less lubricating oil than the first distal nozzle 81, but more than the downward supply nozzle 85. The gap between the five pad surfaces 621 and the outer circumferential surface 1F of the rotor 1 is largest at the position where the first distal pad 71 is located, but it is also larger at the positions where the two second distal pads 72 closest to the first distal pad 71 are located than at the position where the downward pad 75 is located. In other words, in the rotational direction R, as you approach the position where the first distal pad 71, which has the largest gap, is located, from the position of the load point, the size of the gap as seen from the axial direction Da gradually widens. In contrast, by supplying less lubricating oil than the first distal nozzle 81 and more lubricating oil than the downward supply nozzle 85 with the second distal nozzle 82, the necessary amount of lubricating oil that matches the size of the gap can be supplied between the five pad surfaces 621 and the outer circumferential surface 1F of the rotor 1. Therefore, by supplying an appropriate amount of lubricating oil throughout the entire rotational direction R, oversupply of lubricating oil is suppressed, while poor oil film formation due to insufficient lubricating oil is suppressed with high precision, and an oil film can be formed stably. As a result, even when subjected to a large load from the rotor 1, an oil film can be formed stably and with higher precision around the entire circumference.

[0044] (Other embodiments) Although embodiments of this disclosure have been described in detail above with reference to the drawings, the specific configuration is not limited to these embodiments and may include design changes and the like that do not depart from the gist of this disclosure.

[0045] Furthermore, the structure for the upper supply nozzle 80 to supply more lubricating oil than the lower supply nozzle 85 is not limited to simply having different diameters for the oil supply holes 645. For example, the upper supply nozzle 80 may have more oil supply holes 645 than the lower supply nozzle 85. In other words, the upper supply nozzle 80 may have a larger overall opening area for its multiple oil supply holes 645 than the lower supply nozzle 85. Also, the upper supply nozzle 80 may be structured to supply lubricating oil at a higher pressure than the lower supply nozzle 85.

[0046] Furthermore, the upper pad 70 is not limited to having its entire area located above the vertical direction Dv relative to the horizontal plane passing through axis O when viewed from the axial direction Da. The upper pad 70 only needs to have more than half of its area located above the vertical direction Dv relative to the horizontal plane passing through axis O when viewed from the axial direction Da. Similarly, the lower pad 75 is not limited to having its entire area located below the vertical direction Dv relative to the horizontal plane passing through axis O when viewed from the axial direction Da. The lower pad 75 only needs to have more than half of its area located below the vertical direction Dv relative to the horizontal plane passing through axis O when viewed from the axial direction Da.

[0047] Furthermore, the upward supply nozzle 80 is not limited to being located above the vertical direction Dv with respect to the horizontal plane passing through the axis O when viewed from the axial direction Da. The upward supply nozzle 80 can be any supply nozzle 641, 641A that are arranged side by side with respect to the upward pad 70 in the rotational direction R when viewed from the axial direction Da.

[0048] Furthermore, the arrangement of the five pads 62 is not limited to the arrangement of the embodiment described above. For example, when viewed from the axial direction Da, the five pads 62 may be positioned directly below the vertical direction Dv with respect to the axis O. In other words, the journal bearings 6, 6A may be of a type that concentrates the load of the rotor 1 mainly on one pad 62 (Load on Pad: LOP). In that case, the first distal pad 71 and the first distal nozzle 81 will be two of the five.

[0049] <Note> The journal bearings 6 and 6A described in the embodiment are grasped, for example, as follows.

[0050] (1) Journal bearings 6, 6A according to the first embodiment include five pads 62 having pad surfaces 621 that slide against the outer circumferential surface 1F of a rotor 1 that rotates around an axis O, a housing 61 formed in an annular shape centered on the axis O so as to cover the five pads 62, and five lubricating oil supply units 64 each having supply nozzles 641, 641A that supply lubricating oil between the pad surfaces 621 and the outer circumferential surface 1F of the rotor 1 from outside the housing 61, wherein the supply nozzles 641, 641A are arranged between adjacent pads 62 in the rotation direction R of the rotor 1, and five Each of the pads 62 has an upper pad 70 located above the vertical direction Dv with respect to the axis O, and a lower pad 75 located below the vertical direction Dv with respect to the axis O. The five supply nozzles 641, 641A have an upper supply nozzle 80 positioned behind the upper pad 70 in the rotation direction R, and a lower supply nozzle 85 positioned behind the lower pad 75 in the rotation direction R. The upper supply nozzle 80 supplies more lubricating oil between the pad surface 621 and the outer peripheral surface 1F of the rotor 1 than the lower supply nozzle 85.

[0051] With this configuration, the upper supply nozzle 80 supplies more lubricating oil than the lower supply nozzle 85. Therefore, more lubricating oil can be supplied to the gap above the vertical direction Dv where the upper pad 70 is positioned and the gap is wider, compared to the position where the lower pad 75 is positioned. Consequently, poor oil film formation due to insufficient lubricating oil is suppressed in the gap above the vertical direction Dv where the gap is wider, and a stable oil film can be formed. As a result, even when subjected to a large load from the rotor 1, a stable oil film can be formed around the entire circumference.

[0052] (2) Journal bearings 6, 6A according to the second embodiment are the journal bearings 6, 6A of (1), wherein the upper pad 70 has a first distal pad 71 positioned furthest from the load point that receives the most load from the rotor 1 in the rotational direction R, and the upper supply nozzle 80 has a first distal nozzle 81 positioned behind the first distal pad 71 in the rotational direction R, and the first distal nozzle 81 supplies the most lubricating oil among the five supply nozzles 641, 641A between the pad surface 621 and the outer peripheral surface 1F of the rotor 1.

[0053] With this configuration, the largest amount of lubricating oil can be supplied to the gap directly above the axis O in the vertical direction Dv, which is opposite the load point in the rotation direction R and where the gap is widest. Therefore, in the region with the largest gap opposite the load point in the rotation direction R, poor oil film formation due to insufficient lubricating oil can be suppressed with high precision, and an oil film can be formed stably. As a result, even when subjected to a large load from the rotor 1, an oil film can be formed stably and with high precision around the entire circumference.

[0054] (3) Journal bearings 6, 6A according to the third embodiment are the journal bearings 6, 6A of (2), wherein the upper pad 70 further has a second distal pad 72 that is closest to the first distal pad 71 in the rotational direction R, and the upper supply nozzle 80 has a second distal nozzle 82 arranged behind the second distal pad 72 in the rotational direction R, and the second distal nozzle 82 supplies the same amount of lubricating oil as the first distal nozzle 81 or less than the first distal nozzle between the pad surface 621 and the outer peripheral surface 1F of the rotor 1.

[0055] With this configuration, the necessary amount of lubricating oil, matching the size of the gap, can be supplied between the five pad surfaces 621 and the outer circumferential surface 1F of the rotor 1. Therefore, an appropriate amount of lubricating oil can be supplied throughout the entire rotational direction R, suppressing excessive supply of lubricating oil while suppressing poor oil film formation due to insufficient lubricating oil with high precision, and enabling stable oil film formation. As a result, even when subjected to a large load from the rotor 1, the oil film can be formed stably and with higher precision around the entire circumference. [Explanation of Symbols]

[0056] 10... Centrifugal compressor 1…Rotor 11…Rotor body 12... Impeller 1F…Outer surface O…Axis line 3…Casing 31... Inlet 32…Discharge port 5...Bearing part 51…Thrust bearing 6, 6A…Journal bearings 61… Housing 62... pad 621...Pad surface 622... Pad back 63...Support part 64…Lubricating oil supply section 641, 641A… Supply nozzles 645... Fuel filler port 70… Upper pad 71…First distal pad 72...Second distal pad 75... Lower pad 80… Upward supply nozzle 81...First distal nozzle 82...Second distal nozzle 85... Downward supply nozzle Da... Axis Dv…Vertical direction Dr…Radial direction Dc…Circumferential direction R...Direction of rotation

Claims

1. Five pads having pad surfaces that slide against the outer surface of a rotor that rotates around an axis, A housing formed in an annular shape with respect to the axis so as to cover the five pads, The housing comprises five lubrication oil supply units, each having a supply nozzle for supplying lubricating oil between the pad surface and the outer circumferential surface of the rotor from outside the housing, The supply nozzle is positioned between adjacent pads in the rotational direction of the rotor. The five pads include an upper pad located vertically above the axis and a lower pad located vertically below the axis. The five supply nozzles include upper supply nozzles arranged rearward in the rotational direction relative to the upper pad, and lower supply nozzles arranged rearward in the rotational direction relative to the lower pad, The aforementioned upward supply nozzle supplies more lubricating oil between the pad surface and the outer circumferential surface of the rotor than the aforementioned downward supply nozzle, forming a journal bearing.

2. The upper pad has a first distal pad positioned furthest in the rotational direction from the load point that receives the greatest load from the rotor, The upward supply nozzle has a first distal nozzle positioned behind the first distal pad in the rotational direction, The journal bearing according to claim 1, wherein the first distal nozzle supplies the largest amount of lubricating oil among the five supply nozzles between the pad surface and the outer circumferential surface of the rotor.

3. The upper pad further comprises a second distal pad that is closest to the first distal pad in the rotational direction, The upward supply nozzle has a second distal nozzle positioned behind the second distal pad in the rotational direction, The journal bearing according to claim 2, wherein the second distal nozzle supplies the same amount of lubricating oil as the first distal nozzle, or less than the amount supplied by the first distal nozzle, between the pad surface and the outer circumferential surface of the rotor.

Images