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 technology]

[0002] Rotary machines, including gas turbines, steam turbines, and centrifugal compressors, include 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 a bearing device, a journal bearing that supports a load in the radial direction of the rotor and a thrust bearing that supports a load in the axial direction of the rotor are widely used. As a journal bearing, a tilting pad bearing having multiple pads is known.

[0003] For example, Patent Document 1 describes a tilting pad journal bearing device having 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 the gap between the rotor and the bearing pads. A lubricant film (oil film) is formed between the rotor and the plurality of bearing pads by the lubricant oil supplied from the supply unit, 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 the bearing pad located adjacent to the most loaded bearing pad, which is the bearing pad that supports the largest load of the rotor, in the downstream side in the rotation direction of the rotor, is made larger than the amount of lubricant supplied to the other bearing pads. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2017-141882 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the journal bearing having multiple pads as described above, the load of the rotor centered on the axis acts largely on the pads arranged vertically below the rotor. As a result, the gap between the pads arranged vertically below the rotor is small. On the other hand, the gap between the pads and the rotor is large for the pads arranged vertically above the rotor. In particular, if the load from the rotor is very large and the gap between the pads and the rotor becomes too large, the amount of lubricating oil may be insufficient for the size of the gap between the pads and the rotor, and an oil film may not be formed properly. Therefore, it is required to stably form an oil film over the entire circumference even when a large load is applied from the rotor.

[0006] The present disclosure has been made to solve the above-mentioned problems, and has an object to provide a journal bearing capable of stably forming an oil film over the entire circumference. [Means for solving the problem]

[0007] In order to solve the above problems, the journal bearing of the present disclosure comprises five pads having pad surfaces that slidably support the outer peripheral surface of a rotor rotating about an axis, a housing formed in a ring shape centered on the axis so as to cover the five pads, and five lubricating oil supply units each having a supply nozzle that supplies lubricating oil between the pad surface and the outer peripheral surface of the rotor from outside the housing, wherein the supply nozzle is arranged between adjacent pads in the rotational direction of the rotor, and the five pads include upper pads located above in a vertical direction relative to the axis and lower pads located below in the vertical direction relative to the axis, and the five supply nozzles include upper supply nozzles arranged in a row behind the upper pads in the rotational direction, and lower supply nozzles arranged in a row behind the lower pads in the rotational direction, and the upper supply nozzles supply more lubricating oil between the pad surface and the outer peripheral surface of the rotor than the lower supply nozzles. Effect of the Invention

[0008] According to the journal bearing of the present disclosure, an oil film can be stably formed over the entire circumference. [Brief description of the drawings]

[0009] [Figure 1] 1 is a schematic diagram showing a configuration of a centrifugal compressor according to an embodiment of the present invention. FIG. [Diagram 2] 2 is a cross-sectional view perpendicular to the central axis of a journal bearing provided in the centrifugal compressor of the first embodiment. FIG. [Diagram 3] FIG. 11 is a cross-sectional view perpendicular to the central axis of a journal bearing provided in a centrifugal compressor of a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a journal bearing and a rotating machine according to the present invention will be described with reference to the accompanying drawings. However, the present invention is not limited to the embodiment.

[0011] (Configuration of Rotating Machines) The rotating machine is a machine in which a rotor 1 is rotatable relative to a casing 3 by a journal bearing. Examples of the rotating machine include a compressor, a turbine, a motor, and a pump. In this embodiment, a single-shaft multi-stage centrifugal compressor 10, which is a type of compressor, is described as an example of the rotating machine. As shown in FIG. 1, the centrifugal compressor (rotating machine) 10 of this embodiment mainly includes a rotor 1, a casing 3, and a bearing unit 5.

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

[0013] In the following, the direction in which the axis O extends is the axial direction Da. The direction perpendicular to the axial direction Da is 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 along the horizontal plane. In other words, the axis O extends horizontally. The radial direction based on the axis O is simply the radial direction Dr. Also, the direction around the rotor 1 centered on the axis O is the circumferential direction Dc. Furthermore, in the circumferential direction Dc, the direction in which the rotor 1 rotates is the rotation direction R. In the rotation direction R, the one side of the circumferential direction Dc that is the destination of the rotation is the front of the rotation direction R, and the other side of the circumferential direction Dc that is the opposite side of the circumferential direction Dc from the front is the rear of the rotation direction R.

[0014] A plurality of 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 about an axis O. In this embodiment, for example, six impellers 12 are provided in total.

[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 has a cylindrical shape extending in the axial direction Da centered on the axis O. The casing 3 is formed with a suction port 31 for introducing the working fluid into the casing 3 and a discharge port 32 for discharging the working fluid from inside the casing 3 to the outside.

[0017] (Bearing configuration) The bearing portion 5 supports the rotor body 11 rotatably about the axis O. The bearing portion 5 is disposed inside the casing 3. The bearing portion 5 has a thrust bearing 51 and a journal bearing 6.

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

[0019] The journal bearing 6 supports the rotor body 11 at a position close to an end of the rotor body 11 in the axial direction Da relative to the multiple impellers 12. The journal bearing 6 receives a load in the radial direction Dr acting on the rotor body 11. A pair of journal bearings 6 are arranged to sandwich the multiple impellers 12 in the axial direction Da. The journal bearing 6 of this embodiment is a tilting pad bearing having multiple pads 62. As shown in FIG. 2, the journal bearing 6 of this embodiment includes a housing 61, a pad 62, a support portion 63, and a lubricant 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 of the pads 62 and the support portion 63. The housing 61 supports the pads 62 from the outside in the radial direction Dr via the support portion 63 so that they can freely swing. The housing 61 is detachable from the casing 3. A pipe (not shown) that sends lubricating oil supplied from an external supply source to a lubricating oil supply portion 64 is connected to the housing 61.

[0021] Five pads 62 are arranged at intervals in the circumferential direction Dc on the inside in the radial direction Dr with respect to the inner peripheral surface of the housing 61. In this 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 this embodiment is of a type in which the load of the rotor 1 is evenly supported mainly by two pads 62 (Load between Pad: LBP).

[0022] Each pad 62 has an arc shape in a cross section perpendicular to the axis O of the rotor 1, and has a curved plate shape that is wide 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 contact with the outer peripheral surface 1F of the rotor body 11. The pad surface 621 faces the outer peripheral 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 outward 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 peripheral surface 1F of the rotor body 11. Lubricating oil is supplied from the lubricating oil supply unit 64 between the pad surface 621 and the outer peripheral surface 1F of the rotating shaft, so that the lubricating oil is present between the pad surface 621 and the outer peripheral surface 1F of the rotating shaft in a state of forming a film.

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

[0025] The support portion 63 supports the pad 62 so that it can swing relative to the housing 61. When viewed from the circumferential direction Dc, the support portion 63 is disposed between the housing 61 and the pad 62 in the radial direction Dr. Five support portions 63 are disposed at intervals in the circumferential direction Dc so that one support portion 63 is disposed for each pad 62.

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

[0027] When viewed from the axial direction Da, the upper pad 70 is located above the vertical direction Dv with respect to a horizontal plane passing through the axis O, with more than half of the area being 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 upper pads 70. In addition, the multiple upper pads 70 have a first distal pad 71 and a second distal pad 72.

[0028] The first distal pad 71 is disposed at a position farthest in the rotation direction R from a load point that receives the greatest load from the rotor 1. One or two of the five pads 62 are disposed as the first distal pad 71. The first distal pad 71 in this embodiment is only one of the pads 62 that is positioned directly above the axis line O in the vertical direction Dv when viewed from the axial direction Da.

[0029] Here, the load point is a point that receives the largest load from the rotor 1 among the multiple pads 62 that receive a load from the rotor 1 when viewed from the axial direction Da. The load point in this embodiment is a point directly below the vertical direction Dv with respect to the axis O. The load point is not limited to being directly below the vertical direction Dv with respect to the axis O, and may be a position that is slightly inclined (for example, in the range of +45° to -45°). In other words, the load point does not have to be a point on a vertical 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 vertical 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 rotation direction R. Two of the five pads 62 are arranged as the second distal pads 72. The second distal pad 72 in this embodiment is only one of the two pads 62 adjacent to the one first distal pad 71 in the rotation direction R when viewed from the axial direction Da. In other words, the upper pad 70 in this embodiment is composed 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 vertical direction Dv with respect to the horizontal plane passing through the axis O. In this embodiment, two of the five pads 62 are upper pads 70.

[0032] The lubricant supply unit 64 is capable of supplying lubricant between the pad surface 621 and the outer peripheral surface 1F of the rotor 1 from outside the housing 61. The lubricant supply unit 64 is connected to a pipe (not shown) connected to the housing 61. This allows the lubricant supply unit 64 to supply lubricant supplied from a supply source outside the journal bearing 6. The lubricant supply unit 64 supplies lubricant from outside to the inside of the housing 61 when starting and stopping the rotor 1 to start rotating from a completely stopped state (when the rotating machine starts operating, etc.) or when the rotating machine is operating at a rated speed and the rotor 1 continues to rotate at high speed. The lubricant supply unit 64 of this embodiment has five supply nozzles 641.

[0033] The supply nozzle 641 sprays lubricating oil between the pad surface 621 and the outer peripheral surface 1F of the rotor 1. The supply nozzle 641 sprays lubricating oil toward the outer peripheral surface 1F of the rotor 1. The supply nozzle 641 is disposed 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 in the radial direction Dr.

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

[0035] The upper supply nozzles 80 are arranged in the same number as the upper pads 70. In this embodiment, among the five supply nozzles 641, three pads 62 are upper supply nozzles 80. The upper 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 lower supply nozzle 85. In this embodiment, the oil supply hole 645 of the upper supply nozzle 80 is formed larger than the oil supply hole 645 of the lower supply nozzle 85. In addition, the multiple upper supply nozzles 80 have a first distal nozzle 81 and a second distal nozzle 82.

[0036] The first distal nozzle 81 is a part of the upper supply nozzle 80. The first distal nozzle 81 is arranged in a row behind the first distal pad 71 in the rotation direction R. The first distal nozzle 81 supplies the largest amount of lubricant between the pad surface 621 and the outer peripheral surface 1F of the rotor 1 among the five supply nozzles 641. The number of the first distal nozzles 81 is the same as that of the 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 lubricant between the pad surface 621 and the outer peripheral surface 1F of the rotor 1 compared to the amount of lubricant supplied from the lower supply nozzle 85. In other words, the hole area of ​​the supply hole of the first distal nozzle 81 is twice the hole area of ​​the supply hole of the lower supply nozzle 85.

[0037] (Action and effect) In the journal bearing 6 having the above configuration, the five supply nozzles 641 supply lubricant between the five pad surfaces 621 and the outer peripheral surface 1F of the rotor 1. As a result, an oil film is formed by the lubricant between the five pad surfaces 621 and the outer peripheral surface 1F of the rotor 1. Here, the five pads 62 from the rotating shaft receive the largest load from the rotor 1 at the load point. That is, the load point is the point 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 direction Dr of the gap between the five pad surfaces 621 and the outer peripheral 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 size of 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 relative to the axis O, and wider as it approaches directly above the vertical direction Dv relative 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 arranged and the gap is wider than the position where the lower pad 75 is arranged. Therefore, in the gap above the vertical direction Dv where the gap is wider, poor formation of the oil film due to a lack of the amount of lubricating oil can be suppressed, and the oil film can be formed stably. As a result, even if a large load is applied from the rotor 1, the oil film can be formed stably over the entire circumference.

[0039] In this embodiment, the first distal nozzle 81, which supplies lubricating oil from the rear in the rotation direction R to the first distal pad 71 arranged at the farthest position in the rotation direction R from the load point, supplies the largest amount of lubricating oil among the five supply nozzles 641. Therefore, the largest amount of lubricating oil can be supplied to the gap directly above the vertical direction Dv with respect to the axis O, which is the position opposite the load point in the rotation direction R and has the widest gap. Therefore, in the region with the largest gap at the position opposite the load point in the rotation direction R, poor formation of the oil film due to a lack of the amount of lubricating oil can be suppressed with high accuracy, and the oil film can be formed stably. As a result, even if a large load is applied from the rotor 1, the oil film can be formed stably with high accuracy over the entire circumference.

[0040] Second Embodiment Next, a second embodiment of a journal bearing 6A according to the present disclosure will be described. In the journal bearing 6A described below, the same components as those in the first embodiment will be denoted by the same reference numerals in the drawings, and the description thereof will be omitted.

[0041] (Configuration of journal bearing) 3, in the journal bearing 6A of the second embodiment, the configuration of the five supply nozzles 641A is different from that of the first embodiment. The five supply nozzles 641A of the second embodiment have a second distal nozzle 82 in addition to the first distal nozzle 81.

[0042] The second distal nozzle 82 is a part of the upper supply nozzle 80. The second distal nozzle 82 is arranged in line with the second distal pad 72 behind the second distal pad 72 in the rotation direction R. 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 81 between the pad surface 621 and the outer circumferential surface 1F of the rotor 1. The second distal nozzles 82 are arranged in the same number as the second distal pads 72. There are only two second distal nozzles 82 in this embodiment. The second distal nozzles 82 are capable of supplying, for example, 1.5 times the amount of lubricating oil between the pad surface 621 and the outer circumferential surface 1F of the rotor 1 compared to the amount of lubricating oil supplied from the lower supply nozzle 85. In other words, the hole area of ​​the supply hole of the first distal nozzle 81 is twice the hole area of ​​the supply hole of the lower supply nozzle 85.

[0043] (Action and effect) The journal bearing 6A having the above configuration has a second distal nozzle 82 that supplies lubricating oil to the second distal pad 72 that is closest to the first distal pad 71 in the rotation direction R. The second distal nozzle 82 supplies less lubricating oil than the first distal nozzle 81 and more lubricating oil than the lower supply nozzle 85. The gap between the five pad surfaces 621 and the outer peripheral surface 1F of the rotor 1 is largest at the position where the first distal pad 71 is arranged, but the gap is also larger at the position where the two second distal pads 72 closest to the first distal pad 71 are arranged than the position where the lower pad 75 is arranged. In other words, in the rotation direction R, the size of the gap as viewed from the axial direction Da gradually increases as it approaches the position where the first distal pad 71, which has the largest gap, is arranged from the position of the load point. In contrast, the second distal nozzle 82 supplies less lubricating oil than the first distal nozzle 81 and more lubricating oil than the lower supply nozzle 85, so that the required amount of lubricating oil that matches the size of the gap can be supplied between the five pad surfaces 621 and the outer peripheral surface 1F of the rotor 1. Therefore, an appropriate amount of lubricating oil is supplied over the entire range in the direction of rotation R, and excessive supply of lubricating oil is suppressed, while poor oil film formation due to insufficient amount of lubricating oil is suppressed with high accuracy, and an oil film can be formed stably. As a result, even if a large load is applied from the rotor 1, an oil film can be formed stably over the entire circumference with high accuracy.

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

[0045] The structure for allowing the upper supply nozzle 80 to supply more lubricating oil than the lower supply nozzle 85 is not limited to a difference in the hole diameter of the oil feed holes 645. For example, the upper supply nozzle 80 may have a greater number of oil feed holes 645 than the lower supply nozzle 85. In other words, the upper supply nozzle 80 may be formed so that the overall opening area of ​​the multiple oil feed holes 645 is larger than that of the lower supply nozzle 85. Furthermore, the upper supply nozzle 80 may be structured to be able to supply lubricating oil at a higher pressure than the lower supply nozzle 85.

[0046] Further, the upper pad 70 is not limited to having its entire region located above the vertical direction Dv with respect to the horizontal plane passing through the axis O when viewed from the axial direction Da. It is sufficient that 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 when viewed from the axial direction Da. Similarly, the lower pad 75 is not limited to having its entire region located below the vertical direction Dv with respect to the horizontal plane passing through the axis O when viewed from the axial direction Da. It is sufficient that more than half of the lower pad 75 is located below the vertical direction Dv with respect to the horizontal plane passing through the axis O when viewed from the axial direction Da.

[0047] Moreover, the upper 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 upper supply nozzle 80 may be any of the supply nozzles 641, 641A arranged side by side with respect to the upper pad 70 in the rotational direction R when viewed from the axial direction Da.

[0048] Further, the arrangement of the five pads 62 is not limited to the arrangement in the above-mentioned embodiment. For example, the five pads 62 may be arranged directly below the axis O in the vertical direction Dv when viewed from the axial direction Da. In other words, the journal bearings 6, 6A may be of a type (Load on Pad: LOP) in which the load of the rotor 1 is supported intensively mainly by one pad 62. In that case, the first distal pad 71 and the first distal nozzle 81 are two of the five.

[0049] <Additional Notes> The journal bearings 6, 6A according to the embodiment can be understood, for example, as follows.

[0050] (1) A journal bearing 6, 6A according to a first embodiment includes five pads 62 having pad surfaces 621 that slidably support an outer peripheral surface 1F of a rotor 1 rotating about 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 lubricant supply units 64 each having a supply nozzle 641, 641A that supplies lubricant between the pad surface 621 and the outer peripheral surface 1F of the rotor 1 from outside the housing 61, and the supply nozzles 641, 641A are disposed between the pads 62 adjacent to each other in the rotation direction R of the rotor 1, and the five The five pads 62 include an upper pad 70 located above the axis O in the vertical direction Dv, and a lower pad 75 located below the axis O in the vertical direction Dv, and the five supply nozzles 641, 641A include an upper supply nozzle 80 arranged in line behind the upper pad 70 in the rotational direction R, and a lower supply nozzle 85 arranged in line behind the lower pad 75 in the rotational direction R, and 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] According to 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 arranged and the gap is wider than the position where the lower pad 75 is arranged. Therefore, poor oil film formation due to a lack of lubricating oil in the gap above the vertical direction Dv where the gap is wider can be suppressed, and an oil film can be formed stably. As a result, even if a large load is applied from the rotor 1, an oil film can be formed stably around the entire circumference.

[0052] (2) A journal bearing 6, 6A according to a second aspect is a journal bearing 6, 6A according to (1), wherein the upper pad 70 has a first distal pad 71 arranged at a position furthest in the rotational direction R from a load point receiving the greatest load from the rotor 1, the upper supply nozzle 80 has a first distal nozzle 81 arranged next to and behind the first distal pad 71 in the rotational direction R, and the first distal nozzle 81 supplies the largest amount of 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 vertical direction Dv with respect to the axis O, which is the widest gap and is located opposite the load point in the rotation direction R. Therefore, in the region with the largest gap located opposite the load point in the rotation direction R, poor oil film formation due to insufficient amount of lubricating oil can be suppressed with high accuracy, and an oil film can be formed stably. As a result, even if a large load is applied from the rotor 1, an oil film can be formed stably with high accuracy all around.

[0054] (3) A journal bearing 6, 6A according to a third aspect is a journal bearing 6, 6A according to (2), wherein the upper pad 70 further has a second distal pad 72 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 in line with and behind the second distal pad 72 in the rotational direction R, and the second distal nozzle 82 supplies lubricating oil between the pad surface 621 and the outer peripheral surface 1F of the rotor 1 in an amount equal to or less than that of the first distal nozzle 81.

[0055] With this configuration, the necessary amount of lubricating oil according to 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 over the entire area in the rotation direction R, and excessive supply of lubricating oil can be suppressed while poor oil film formation due to insufficient amount of lubricating oil can be suppressed with high accuracy, and an oil film can be formed stably. As a result, even if a large load is applied from the rotor 1, an oil film can be formed stably with high accuracy over 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…Suction port 32…Discharge port 5...Bearing part 51...Thrust bearing 6, 6A...Journal bearing 61…Housing 62…Pad 621…Pad surface 622…Back of pad 63...Support part 64…Lubricating oil supply section 641, 641A…Supply nozzle 645…Fuel hole 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…Axial direction Dv: Vertical direction Dr…Radial direction Dc…Circumferential direction R…Rotation direction

Claims

1. five pads each having a pad surface that supports an outer circumferential surface of a rotor that rotates about an axis so as to be in sliding contact with the outer circumferential surface of the rotor; a housing formed in an annular shape around the axis so as to cover the five pads; five lubricant oil supply units each having a supply nozzle for supplying lubricant oil between the pad surface and the outer peripheral surface of the rotor from outside the housing; the supply nozzle is disposed between adjacent pads in a rotational direction of the rotor, The five pads include an upper pad located above the axis in a vertical direction and a lower pad located below the axis in the vertical direction, The five supply nozzles include upper supply nozzles arranged side by side behind the upper pad in the rotational direction, and lower supply nozzles arranged side by side behind the lower pad in the rotational direction, A journal bearing in which the upper supply nozzle supplies more lubricating oil between the pad surface and the outer peripheral surface of the rotor than the lower supply nozzle.

2. The upper pad has a first distal pad disposed at a position farthest in the rotational direction from a load point that receives the greatest load from the rotor, The upper supply nozzle has a first distal nozzle arranged rearwardly in the rotational direction relative to the first distal pad, 2. The journal bearing of claim 1, wherein the first distal nozzle supplies the largest amount of lubricating oil between the pad surface and the outer peripheral surface of the rotor among the five supply nozzles.

3. the upper pad further includes a second distal pad rotationally closest to the first distal pad; the upper supply nozzle has a second distal nozzle arranged in line with the second distal pad and rearward in the rotational direction; The journal bearing of claim 2 , wherein the second distal nozzle supplies lubricating oil between the pad surface and the outer peripheral surface of the rotor in an amount equal to or less than that of the first distal nozzle.

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