JP2017072173A - Tilting-pad journal bearing and turbo machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tilting-pad journal bearing with high stability.SOLUTION: A tilting-pad journal bearing 100 is configured such that a plurality of circular-arc shaped pads 3, 3, 3are respectively mounted inside a bearing inner ring 4 in an oscillatable manner around supporting points 5, 5, 5of a pad back face, wherein among the plurality of pads, arc angels θb, θc of the second pad 3and third pad 3arranged in a horizontal direction so as to be adjacent to both sides of the first pad 3are made smaller an arc angle θa of the first pad 3arranged right below in a vertical direction.SELECTED DRAWING: Figure 1

Description

  Embodiments described herein relate generally to a tilting pad journal bearing and a turbomachine.

  A tilting pad journal bearing is adopted as a journal bearing that stably supports a rotating shaft of a large-scale high-speed rotating machine such as a turbo machine typified by a steam turbine or a generator driven by the turbine. A configuration of a conventional tilting pad journal bearing will be described with reference to FIG. FIG. 17 is a cross-sectional view schematically showing a conventional tilting pad journal bearing that stably supports a rotating shaft of a turbine or a generator.

As shown in FIG. 17, the tilting pad journal bearing 100 includes an arc-shaped pad 3 (3 ₁ , 3 ₂ , 3 ₃ ... 3 ₆ ) and a bearing inner ring 4 (4 ₁ , 4 ₂ ) and a pivot 5 (5 ₁ , 5 ₂ , 5 ₃ ... 5 ₆ ). The arc-shaped pads 3 (3 ₁ , 3 ₂ , 3 ₃ ... 3 ₆ ) are arranged at substantially equal intervals in the direction of arrow rotation of the journal (shaft neck) 2 of the rotating shaft. I support it. Bearing inner ring _{4 (4} 1, _{4 2)} supports so as to surround each pad _{3 1,} 3 _2, 3 3 ... _{3 6} from the outside. Pivot _{5 (5} 1, _{5 2,} 5 3, ... _{5 6),} the journal 2 by attached to the bearing inner ring 4, for supporting the back of each pad _{3 1,} 3 _2, 3 3 ... _{3 6} are swingable each pad _{3 1,} 3 _2, 3 3 ... _{3 6} against movement. Actually, there is a bearing outer ring outside the bearing inner ring 4, and the bearing outer ring is fixed to the bearing casing or the foundation, but it is not shown here. In the tilting pad journal bearing 100 configured as described above, lubricating oil is used as a lubricant, and this lubricating oil is moved by the friction generated between the rotating journal 2 and the pad 3 to move between the journal 2 and the journal 2. It is supplied between the pads 3.

  The tilt state of the pad 3 and the wedge effect will be described with reference to FIG. FIG. 18 is an enlarged view drawn paying attention to any one of the plurality of pads 3. As shown in FIG. 18, a straight line indicated by a one-dot chain line passing through the center of curvature Ob of the inner surface 4 a of the bearing inner ring 4, the center of curvature Op of the sliding surface 3 a of the pad 3, and the center of gravity G of the pad 3, that is, the pad 3. A straight line L1 passing through the center position of the pad 3 is drawn, and a straight line L2 perpendicular to the straight line L1 is drawn from the center of gravity G of the pad 3, and this vertical straight line L2 is drawn to the reference angle (0 °). Here, if the angle when the pad 3 is tilted counterclockwise with the pivot 5 as a fulcrum is defined as the positive (+) side, and the angle when the pad 3 is tilted clockwise is defined as the negative (−) side, the journal 2 is viewed in the direction of the arrow. When the pad 3 rotates in the counterclockwise direction, the pad 3 tilts counterclockwise, and the tilt angle α of the pad 3 becomes positive (+).

  As described above, the lubricant is supplied to the gap C between the journal 2 and the pad 3 by the rotation of the journal 2, but the pad 3 is stationary while the journal 2 rotates at a high peripheral speed. Therefore, the lubricating oil supplied to the gap C between the sliding surface 2a of the journal 2 and the lubricating surface 3a of the pad 3 causes a very large speed difference between the journal 2 side and the pad 3 side.

When a speed difference occurs in the lubricating oil, a shearing force acts on the lubricating oil and a viscous force is generated inside the lubricating oil. This wedge action and the tilting state of the pad 3 formed by the movement of the journal 2 and the pad 3 cause a wedge effect between the two, and the lower pad of the journal 2 and the three lower half parts supporting the load applied to the journal 2. Oil film pressure distributions P6, P1 and P2 as shown in FIG. 17 are generated in the lubricating oil supplied to the gap C between 3 ₆ , 3 ₁ and 3 ₂ .

When the entire circumference integrating the oil film pressure distribution P6, P1 and P2 that occur below the pads ₃ 6 halves, _{3 1} and _{3 2} matches the load W applied to the journal 2. Here, to describe the pads 31 of the bottom (underneath), the contact point T1 between the back and the pivot 5 ₁ of the pad 3 _1, vertically below the center point of the oil film pressure distribution P1 which varies in accordance with the rotation of the journal 2 Move freely to be located at. Such behavior is also true for the pad 3 ₂ and pads 3 ₆ adjacent to both sides of the pad 3 ₁ of the bottom (underneath).

  In this way, the pad 3 is self-aligned and receives the bearing load W as a whole, and can prevent the occurrence of destabilizing force that generates oil whip, so the tilting pad journal bearing is self-aligning. It is functional and excellent in stability, and is particularly suited for high-speed rotating machines that require high stability.

JP2013-29135A

  However, in recent years, as the tendency of steam turbines and generators to increase in size and speed has increased, unstable vibrations are likely to occur even in tilting pad journal bearings having excellent stability. Furthermore, as a result of measures to improve the performance of turbomachinery, the number of paragraphs, leakage loss, high temperature, and high pressure are prominent. These include reduction of critical speed of shaft system, reduction of system damping, destabilization seal The tendency to decrease the stability against the vibration of the shaft system such as the increase of force is increasing.

  Among them, unstable vibrations with the following characteristics have been confirmed. There is load dependency, and it does not occur at all while the load is small, or even if it occurs, the amplitude is small and does not matter. When the load becomes large, it occurs for the first time, or the amplitude grows rapidly and vibrates vigorously. It becomes difficult to increase the load any more.

In addition, there are many cases where unstable vibration occurs in the region where the vibration frequency is close to the primary natural frequency of the shaft system and the rotation speed of the shaft exceeds the primary critical speed, and therefore the vibration frequency is higher than the rotation synchronization frequency. Is also low. The cause of such vibration is the fluid force by the working fluid, which is called the destabilizing force, and is often modeled by a coupled spring term as in the following equation (1).

  Therefore, an embodiment of the present invention has been made in consideration of such points, and an object thereof is to provide a tilting pad journal bearing with higher stability.

The tilting pad journal bearing according to the present embodiment is a tilting pad journal bearing in which a plurality of arc-shaped pads are incorporated inside a bearing inner ring so as to be swingable around a support point on the back surface of the pad.
Among the plurality of pads, the arc angle of the second pad and the third pad arranged in the horizontal direction adjacent to both sides of the first pad is larger than the arc angle of the first pad arranged directly below the vertical direction. It is small.

The turbo machine according to the present embodiment is provided in a casing in which a plurality of stator blade cascades are disposed, a turbine rotor that is rotatably passed through the casing, and the turbine rotor, and is alternately disposed with the stationary blade cascades. A turbomachine comprising: a turbine rotating body having a plurality of rotor blade cascades; and a tilting pad journal bearing that rotatably supports a journal of the turbine rotor with respect to the casing, wherein the tilting pad journal bearing is provided. Is a tilting pad journal bearing in which a plurality of arc-shaped pads are built in a bearing inner ring so as to be swingable around a support point on the back of the pad,
Among the plurality of pads, the arc angle of the second pad and the third pad arranged in the horizontal direction adjacent to both sides of the first pad is larger than the arc angle of the first pad arranged directly below the vertical direction. It is small.

  According to this embodiment, a more stable tilting pad journal bearing can be provided.

Sectional drawing which shows the lower half part of the tilting pad journal bearing which concerns on 1st Embodiment. The figure explaining simulation in order to obtain oil film force. The figure explaining the shape of the pad concerning a 2nd embodiment. The figure explaining the shape of the pad concerning a 3rd embodiment. The figure explaining the shape of the pad concerning a 4th embodiment. The figure explaining the oil supply structure of the conventional tilting pad journal bearing. The figure explaining the shape of the 1st pad concerning a 5th embodiment. The figure explaining the shape of the 1st pad concerning a 6th embodiment. The figure explaining the shape of the pad concerning a 7th embodiment. The figure explaining the deformation | transformation of a 3rd pad. The figure explaining the clearance gap between a journal and a 3rd pad. The figure explaining the clearance gap between a journal and a pad. The figure explaining the shape of the pad concerning an 8th embodiment. The figure explaining the shape of the pad concerning a 9th embodiment. The figure explaining the shape of the pad concerning a 10th embodiment. The figure which shows the cross section containing the axis line X of the turbine rotary body of a steam turbine. The cross-sectional view which shows the conventional tilting pad journal bearing typically. The enlarged view drawn paying attention to arbitrary one of a plurality of pads.

  Embodiments of the present invention will be described below with reference to the drawings. This embodiment does not limit the present invention.

(First embodiment)
The tilting pad journal bearing according to the first embodiment includes a second pad and a third pad disposed in the horizontal direction adjacent to both sides of the first pad rather than the arc angle of the first pad disposed directly below the vertical direction. By reducing the arc angle of the pad, the anisotropy of the bearing oil film force is further increased to prevent the occurrence of unstable vibration. More details will be described below.

(Constitution)
Based on FIG. 1, the structure of the tilting pad journal bearing 100 which concerns on 1st Embodiment is demonstrated. Throughout the drawings, the same parts and the same elements are denoted by the same reference numerals, and overlapping descriptions are omitted as appropriate. FIG. 1 is a cross-sectional view showing a lower half portion of a tilting pad journal bearing 100 according to the first embodiment.

As shown in FIG. 1, the tilting pad journal bearing 100 includes an arc-shaped pad 3 (3 ₁ , 3 _{2 ′} , 3 ₃ ... 3 _{6 ′} ), a bearing inner ring 4, and a pivot 5 (5 ₁ 5 ₂ , 5 ₃ ... 5 ₆ ). The arc-shaped pads 3 (3 ₁ , 3 _{2 ′} , 3 ₃ ... 3 _{6 ′} ) are arranged at substantially equal intervals in the direction of rotation of the journal (shaft neck) 2 of the rotating shaft. 2 is supported. Here, the journal 2 is a turbine rotor journal in a turbomachine, for example, a turbine rotor journal in a steam turbine. W indicates the load direction of the load W of the journal 2, and indicates directly below the vertical direction. The load direction here is the direction of gravity.

As described above, the bearing inner ring 4 supports the pad 3 (3 ₁ , 3 _{2 ′} , 3 ₃ ... 3 _{6 ′} ) so as to surround from the outside. Pivot _{5 (5} 1, _{5 2,} 5 3, ... _{5 6)} is attached to the bearing inner ring 4, each pad ₃ 1, 3 _{2 ', 3} 3 ... 3 _6' by supporting the back of the Each pad 3 ₁ , 3 _{2 ′} , 3 ₃ ... 3 _{6 ′} ′ can swing with respect to the movement of the journal 2.

Tilting pad first pad 3 ₁ disposed in the lower half of the journal bearing 1 _', second pad 3 _2', and a third of the pad 3 _{6 ',} the first pad 3 disposed beneath vertically ₁ The arc angles θb and θc of the second pad 32 _′ and the third pad 36 _′ arranged in the horizontal direction adjacent to both sides of the first pad 31 are smaller than the arc angle θa of the first pad 31. That is, toward the second pad 3 _{2 ',} and the third pad 3 _6', respectively the front area is made smaller than the first front area of the pad 3 _1. Here, the arc angle is an angle indicating the length in the circumferential direction of each pad 3 ₁ , 3 _{2 ′} , 3 ₃ ... 3 _{6 ′} . Here, for example, as indicated by arc angles θa, θb, and θc in FIG. 1, the angle is a line segment that connects the center of curvature of the bearing inner ring 4 and both ends of the front surface of the pad. In this example, the angle between the line segments connecting the center of curvature of the bearing inner ring 4 and both ends of the back surface of the pad also reaches the arc angle. Further, for example, an angle between line segments connecting a circumferential curvature point on the front surface of the pad and both end portions on the front surface of the pad may be an arc angle.

(Function)
As described above, the second pad 3 _{2 ',} third pad 3 _6' by which to reduce the firing angle of a range of oil film occurs when the journal 2 second pad 3 _{2 ',} third pad 3 _6' between but smaller than the range of oil film occurs when the journal 2 between the first pad 3 _1. Thereby, the load applied to the second pad 3 _{2 ′} and the third pad 36 _′ is further reduced. That is, by reducing the oil film force in the horizontal direction, the anisotropy of the bearing oil film force is further increased.

Next, simulation for obtaining the oil film force will be described with reference to FIG. FIG. 2 is a diagram for explaining the simulation for obtaining the oil film force. In FIG. 2, there is a gap C between the journal 2 and the pads 3 ₁ , 3 _{2 ′} , 3 _{6 ′ in the} lower half corresponding to the difference between the inner surface of the pad 3, that is, the radius rj between the pad front surface and the journal 2. Is formed. When the journal 2 rotates, the journal 2 descends to a position where the oil film force formed in the gap C between the journal 2 and the pad 3 and the weight of the journal 2 are balanced (the journal indicated by the broken line is the position 2 '). The center moves from O1 to O2 eccentric by an eccentricity amount e.

The gaps h1, h2, and h6 formed between the journal 2 ′ and each pad 3 at this time are expressed by the following equation (2).

Here, ε represents e / C and means the eccentricity, and Φ represents an angle in the circumferential direction with respect to the original journal 2 with the eccentric direction O1-O2 in FIG. 2 as a reference. Α6 indicates the inclination of the third pad 36 _′ , and β1 and β2 indicate the length from the fulcrum position of the third pad 36 _{′ to} the rear end and the front end in the rotation direction of the journal 2. Rj represents the radius of the journal 2, and Op6 represents the angle from the straight line connecting the eccentric directions O1-O2 to the fulcrum of the pad 36 _' .

In such a tilting pad journal bearing, the oil film pressure p generated for each pad 3 with respect to the weight of the journal 2 'is expressed by the following equation (3), where the circumferential coordinate is θ and the axial coordinate is z. It is obtained from the lubrication equation shown below.

Here, μ represents the temperature of the lubricating oil, and U represents the peripheral speed of the journal. In the tilting pad journal bearing 100, the oil film pressure is generated on the pad surface so that the moment around the pivot installed at the approximate center of the pad becomes zero. If the inertia of the pad is ignored, Equation (4) is obtained from the balance of moments around the pivot, and Equation (5) is obtained from the balance of the load Wpi applied to the pad and the oil film force.

The oil film force of each of the pads 3 ₁ , 3 _{2 ′} and 3 _{6 ′} can be obtained by simulating the theoretical formulas expressed by the equations (4) and (5) on a computer. This simulation results, by having a smaller arc angle of the second pad 3 _{2 'and} the third pad 3 _6' located horizontally left and right of the first pad 3 ₁ positioned just below, each pad 3 _{2 'and} 3 load on the _{6 'decreases,} mainly oil film force in the horizontal direction is also reduced, the first pad 3 ₁ load on the positioned just below along with it increased as a result of oil film strength in the vertical direction is increased to obtain . That is, the anisotropy of the bearing oil film force increases. As described above, the oil film force of the tilting pad journal bearing 100 is obtained by the theoretical formula obtained from the lubrication equation (3), the formula (4) regarding the balance of moments around the pivot, and the formula (4) regarding the balance between the load applied to the pad and the oil film force ( 5) can be obtained by simulating on a computer.

(effect)
As described above, according to the tilting pad journal bearing 100 according to the present embodiment, than the first pad 3 ₁ of firing angle arranged beneath the vertical direction, the horizontal direction adjacent to both sides of the first pad The arc angle of the arranged second pad 32 _' and third pad 36 _' was reduced. Accordingly, the anisotropy of the bearing oil film force is increased by further reducing the oil film force in the horizontal direction in the second pad 3 _{2 ',} and the third pad 3 _6', instability due to destabilizing forces from the working fluid It is possible to provide a tilting pad journal bearing that can prevent the occurrence of vibration and has good stability.

(Second Embodiment)
The tilting pad journal bearing according to the second embodiment includes a second pad disposed in the horizontal direction adjacent to both sides of the first pad, rather than the axial length of the first pad disposed directly below the vertical direction. By shortening the axial length of the third pad, the anisotropy of the bearing oil film force is further increased to prevent the occurrence of unstable vibration. Hereinafter, a different part from 1st Embodiment mentioned above is demonstrated.

(Constitution)
A pad 3 ′ according to the second embodiment will be described with reference to FIG. FIG. 3 is a diagram illustrating the shape of the pad 3 ′ according to the second embodiment. As shown in FIG. 3, the axial length L of the pads arranged in the horizontal direction is shortened, which is different from the first embodiment. That is, among the first pad 3 ₁ , the second pad 3 _{2 ′} , and the third pad 3 _{6 ′} disposed in the lower half of the tilting pad journal bearing 1, the first pad 3 disposed directly below in the vertical direction. than the axial length L of _1, to shorten the axial length of the second pad 3 _{2 ',} and the third pad 3 _6' arranged horizontally adjacent to the first sides of the pad 3 _1, L 'It was.

In the present embodiment, the arc angle θa and the arc angles θb and θc are configured to be the same angle. That is, the circumferential length of the first pad 31 _{′ and} the circumferential length of the second pad 32 _′ and the third pad 36 _′ are configured to be equal.

(Function)
As described above, the pad 3 _{2 ',} 3 _6' by that shorten the axial length of the journal 2 and the pad 3 _{2 ',} 3 _6' range of oil film occurs between the journal 2 and the first pad 3 _It becomes smaller than the range of the oil film generated between ₁ . Thereby, the load applied to the pads 3 _{2 ′} and 3 _{6 ′} is further reduced. That is, by reducing the oil film force in the horizontal direction, it is possible to further increase the anisotropy of the bearing oil film force. In addition, since the arc angle θa and the arc angles θb and θc are configured to be the same angle, the circumferential oil film range of the second pad 32 _′ and the third pad 36 _′ is set to a range equivalent to the conventional one. It is possible to

(effect)
As described above, according to the tilting pad journal bearing 100 according to the present embodiment, than the first axial length of the pad 3 ₁ arranged beneath the vertical direction, horizontal direction and adjacent to both sides of the first pad it was decided to shorten the axial length of the second pad 3 ₂ arranged _'and the third pad 3 _6' to. As a result, the anisotropy of the bearing oil film force is further increased by further reducing the oil film force in the horizontal direction at the second pad 32 _' and the third pad 36 _' , which is equivalent to that of the first embodiment. An effect can be obtained. Further, while maintaining the anisotropy of the bearing oil film force, the oil film range in the circumferential direction of the second pad 32 _' and the third pad 36 _' can be made equal to the conventional range.

(Third embodiment)
The tilting pad journal bearing according to the third embodiment has a second horizontal arrangement adjacent to both sides of the first pad, rather than the arc angle and axial length of the first pad arranged directly below the vertical direction. By reducing the arc angle of the pad and the third pad and shortening the axial length, the anisotropy of the bearing oil film force is further increased to prevent the occurrence of unstable vibration. Hereinafter, a different part from 1st Embodiment mentioned above is demonstrated.

(Constitution)
A pad 3 '' according to the third embodiment will be described with reference to FIG. FIG. 4 is a diagram for explaining the shape of the pad 3 ″ according to the third embodiment. As shown in FIG. 4, the length L in the axial direction of the pad is shortened to L ′, which is different from the first embodiment. In other words, the pad 3 ₁ placed in the lower half of tilting pad journal bearing _1, 3 2 _', and 3 _6' of, from the first axial direction of the pad 3 ₁ length L disposed directly below the vertical direction also, the axial length of the first second pad 3 _{1 'and} the third pad 3 _6' arranged horizontally adjacent to both sides of the pad 3 ₁ shortening is obtained by a L '.

(Function)
As described above, the pad 3 _{2 ',} 3 _6' reduces the firing angle of, and the pad 3 _{2 ',} 3 _6' by that shorten the axial length of the journal 2 and the pad 3 _{2 ',} 3 _6' The range of the oil film generated between them is smaller than the range of the oil film generated between the journal 2 and the pad 31 _′ . Thereby, the load applied to the pads 3 _{2 ′} and 3 _{6 ′} is further reduced. That is, by reducing the oil film force in the horizontal direction, it is possible to further increase the anisotropy of the bearing oil film force. Further, while maintaining the oil film range in which anisotropy occurs, the circumferential length and axial length of the second pad 3 _{2 ′} and the third pad 36 _′ are changed, and the second pad 3 _{2 ′} and it is possible to form a third pad _{3 6.} Thereby, the oil film ranges in the circumferential direction and the axial direction of the second pad 32 _' and the third pad 36 _' can be changed according to the rotation and load characteristics of the journal 2.

(effect)
As described above, according to the tilting pad journal bearing 100 according to the present embodiment, than the first arc angle of the pad 3 ₁ and the axial length disposed beneath the vertical direction, adjacent on both sides of the first pad the second pad 3 _{2 ',} and the third pad 3 _6' as well as reduce the firing angle of, than the axial length of the first pad 3 ₁ second pad 3 _{2 'and} a third pad 3 arranged horizontally Te _{The 6 '} axial length was shortened. Thereby, the anisotropy of the bearing oil film force is further increased, and the occurrence of unstable vibration due to the destabilizing force from the working fluid can be prevented. In addition, while maintaining the anisotropy of the bearing oil film force, the oil film ranges in the circumferential direction and the axial direction of the second pad 32 _' and the third pad 36 _' can be changed.

(Fourth embodiment)
The tilting pad journal bearing according to the fourth embodiment includes a second pad and a third pad disposed in the horizontal direction adjacent to both sides of the first pad, rather than the arc angle of the first pad disposed directly below the vertical direction. By reducing the arc angle of the pad and arranging the lubricating oil supply hole on the upstream side of the rotation of the first pad, the bearing oil film force anisotropy is further increased and the bearing loss is further reduced. . Hereinafter, a different part from 1st Embodiment mentioned above is demonstrated.

(Constitution)
A first pad 3 ₁ according to the fourth embodiment will be described with reference to FIG. Figure 5 is a diagram for explaining a first pad 3 ₁ shaped according to the fourth embodiment. As shown in FIG. 5, in this arranging the lubricating oil supply hole 6 in the first rotation upstream side of the pad 3 _1, it differs from the first embodiment. An external oil supply hole 7 is provided at a position corresponding to the lubricating oil supply hole 6 of the bearing inner ring 4.

(Function)
A conventional oiling structure of a tilting pad journal bearing will be described with reference to FIG. FIG. 6 is a diagram illustrating a conventional oiling structure of a tilting pad journal bearing. As shown in FIG. 6, the lubricating oil circulates between the journal 2 and the pad 3 in the flow of the arrow 9 from the oil supply hole 8, and the bearing is in a state filled with oil. In the present embodiment, the space made by the firing angle of the third pad 3 _{6 'becomes} small, and the pad oil supply hole 6 provided in the first rotation upstream side of the pad 3 _1. Thus, it is possible to externally supply hole 7 through the pad supply hole 6, to supply the amount corresponding lubricating oil required the journal 2 to the first pad 3 ₁ of the gap. The first pad 3 _1, because it is the most subjected pad load of the journal 2, it is possible to efficiently supply the lubricating oil, it is more possible to reduce the bearing loss.

(effect)
As described above, according to the tilting pad journal bearing 100 according to the present embodiment, than the first pad 3 ₁ of firing angle arranged beneath the vertical direction, the horizontal and adjacent to the first sides of the pad 3 ₁ both reduce the firing angle of the second pad 3 _{2 ',} and the third pad 3 _6' arranged in the direction, it was decided to the first rotation upstream side of the pad 3 ₁ provided pad oil supply hole 6. Thus, it is possible to obtain the same effect as the first embodiment, it is possible to efficiently supply the lubricating oil to the first pad 3 ₁ most under load, it is possible to further reduce the bearing loss.

(Fifth embodiment)
In the tilting pad journal bearing according to the fifth embodiment, the anisotropy of the bearing oil film force can be obtained by configuring the arc angle of the first pad arranged directly below the vertical direction to be larger than the arc angle of the other pads. I tried to increase it. Hereinafter, a different part from 1st Embodiment mentioned above is demonstrated.

(Constitution)
A first pad 31 _' according to the fifth embodiment will be described with reference to FIG. FIG. 7 is a view for explaining the shape of the first pad 31 _{′ according} to the fifth embodiment. As shown in FIG. 7, was equivalent to the second pad 3 _2, and arc angle of the third pad 3 ₆ Conventional disposed horizontally, the first pad 3 _{1 'of} the pad firing angle .theta.a' beneath This is larger than the arc angle of the left and right pads 3 ₂ , 3 ₆ . That is, the arc angle at the first pad 3 _{1 ′} that receives the load of the journal 2 most is larger than the arc angle of the other pads in the pad 3 (3 _{1 ′} , 3 ₂ , 3 ₃ ... 3 ₆ ). It is configured. Incidentally, with increasing the firing angle of the first pad 3 _{1 'beneath,} even by reducing the firing angle of the second pad 3, _second and third pad 3 ₆ arranged horizontally as in the first embodiment Good.

(Function)
As described above, in FIG. 7, as the arc angle of the first pad 31 _′ increases, the range of the oil film generated between the journal 2 and the pad 31 _′ increases. As a result, the load applied to the first pad 31 _′ increases. That is, by increasing the oil film force in the vertical direction, the same effect as in the first embodiment is obtained, and the anisotropy of the bearing oil film force can be increased. Thus, the anisotropy of the bearing oil film force can be increased by further increasing the oil film force in the vertical direction. Further, the characteristics of the other pads in the pad 3 (3 _{1 ′} , 3 ₂ , 3 ₃ ... 3 ₆ ) can be maintained at the same level as the conventional one.

(effect)
As described above, according to the tilting pad journal bearing 100 according to the present embodiment, the arc angle of the first pad 3 _{1 ′} disposed directly below the vertical direction is set to the pad 3 (3 _{1 ′} , 3 ₂ , 3 ₃ .., 3 ₆ ) larger than the arc angle of the other pads. Thus, that oil film strength of the first pad 3 ₁ in the vertical direction more increases the anisotropy of the bearing oil film forces by increasing more, preventing the occurrence of unstable vibration by destabilizing forces from the working fluid it can. Further, the characteristics of the other pads in the pad 3 (3 _{1 ′} , 3 ₂ , 3 ₃ ... 3 ₆ ) can be maintained at the same level as the conventional one.

(Sixth embodiment)
In the tilting pad journal bearing according to the sixth embodiment, the axial length of the first pad arranged directly below the vertical direction is made longer than the axial length of the other pads, so that the bearing oil film force is anisotropic. It is intended to increase the sex. Hereinafter, a different part from 1st Embodiment mentioned above is demonstrated.

(Constitution)
A first pad 31 _' according to the sixth embodiment will be described with reference to FIG. FIG. 8 is a view for explaining the shape of the first pad 31 _{′ according} to the sixth embodiment. As shown in FIG. 8, the axial length L of the second pad _{3, second} and third pad 3 ₆ disposed horizontally unchanged, the axial length of the first pad 3 _{1 'directly} below L 'Is made longer. That is, the axial length of the first pad 3 _{1 ′} that receives the most load of the journal 2 is the axial length of other pads in the pad 3 (3 _{1 ′} , 3 ₂ , 3 ₃ ... 3 ₆ ). Longer than that. That is, the axial length of the first pad 3 _{1 ″} receiving the load of the journal 2 is the axial direction of the other pads in the pad 3 (3 _{1 ′} , 3 ₂ , 3 ₃ ... 3 ₆ ). It is configured to be larger than the length.

Note that the axial length of the pad 31 _{1 ′} directly below may be increased, and the arc angles of the left and right pads 3 ₂ , 3 ₆ may be reduced as in the first embodiment. In addition, the length in the axial direction of the pad 31 _′ immediately below may be increased and the arc angle may be increased.

(Function)
As described above, since the axial length of the first pad 31 _′ installed directly below becomes longer, the range of the oil film generated between the journal 2 and the first pad 31 _′ increases. As a result, the load applied to the first pad 31 _′ increases. That is, by increasing the oil film force in the vertical direction, the same effect as in the first embodiment is obtained, and the anisotropy of the bearing oil film force can be increased. Thus, the anisotropy of the bearing oil film force can be further increased by relatively increasing the oil film force in the vertical direction of the first pad 31 _′ .

(effect)
As described above, according to the tilting pad journal bearing 100 according to the present embodiment, the axial length of the first pad 3 _{1 ′} disposed directly below the vertical direction is set to the pad 3 (3 _{1 ′} , 3 ₂ , 3 ₃ ... 3 ₆ ), which is longer than the axial length of the other pads. As a result, the oil film force in the vertical direction of the first pad 31 _' increases further, so that the anisotropy of the bearing oil film force increases, and the occurrence of unstable vibration due to the destabilizing force from the working fluid is prevented. Can do. Further, the characteristics of the other pads in the pad 3 (3 _{1 ′} , 3 ₂ , 3 ₃ ... 3 ₆ ) can be maintained at the same level as the conventional one.

(Seventh embodiment)
The tilting pad journal bearing according to the seventh embodiment is disposed in the horizontal direction adjacent to both sides of the first pad, rather than the circumferential curvature radius arc angle of the back surface of the pad in the first pad disposed directly below the vertical direction. The anisotropy of the bearing oil film force is further increased by reducing the circumferential curvature radius arc angle of the back surface of the pad in the second pad and the third pad arranged in the horizontal direction of the second pad and the third pad. It tries to prevent the occurrence of unstable vibration. Hereinafter, a different part from 1st Embodiment mentioned above is demonstrated.

(Constitution)
The second pad 3 ₂ according to the seventh embodiment _', and the third pad 3 _6' will be described based on FIGS. 9 to 12. FIG. 9 is a view for explaining the shapes of the pads 3 _{2 ′} and 3 _{6 ′ according} to the seventh embodiment. As shown in FIG. 9, a second pad 3 _{2 ',} and the third pad ₃ pad back ₁₀ 2 of _6, 10 ₆ in the circumferential direction radius of curvature R1' is smaller than the first pad _{3 1} of the circumferential radius of curvature R1 It is comprised so that it may become.

(Function)
The deformation of the third pad 36 _' when receiving the pressure P from the journal 2 will be described with reference to FIG. FIG. 10 is a diagram for explaining a modification of the third pad 36 _′ . As shown in this FIG. 10, when the third pad 3 _{6 'receives} the pressure P from the journal 2, the amount of deformation due to contact pads back ₁₀₆ and the bearing inner ring inner surface 4a [delta] is generated. According to Hertz's theory, the relationship between the deformation amount δ and the pressure P is as follows: the circumferential curvature radius R1 of the pad back surface at the contact point, the axial curvature radius R2, the circumferential curvature radius R3 of the inner surface of the bearing inner ring, and the axial curvature radius. When R4, it is shown by the formula (6) and the formula (7).

Here, E is the longitudinal elastic modulus, ν is the Poisson's ratio, and λ is a constant determined from the angle formed by the curvature of the contact surface. For this reason, when the circumferential curvature radius R1 on the back surface of the pad becomes smaller, A becomes larger and the deformation amount δ becomes larger. When the deformation amount δ increases, the gap between the journal 2 and the third pad 36 _′ increases. As can be seen from this, as the circumferential curvature radius R1 on the back surface of the pad decreases, the deformation amount δ increases for the same pressure P.

Based on FIG. 11, described _'clearance C between' the journal 2 third pad 3 _6. Figure 11 is a diagram for explaining _'clearance C between' the journal 2 third pad 3 _6. In FIG. 11, rs is the radius of the journal 2, rp is the inner surface of the third pad 3 ₆ from the center of before the pressure P applied, that is, the distance to the pad front, rp 'from the center after the pressure is applied P It shows a distance to the pad front of the third pad 3 _6. The difference between rp ′ and rp corresponds to the deformation amount δ. That is, a _'gap C between' the journal 2 after under pressure P third pad 3 _6, the difference is the amount of deformation of the clearance C between the journal 2 before the pressure P is applied to the third pad 3 _{6 '} corresponds to δ.

The gaps h1, h2, and h6 will be described with reference to FIG. FIG. 12 is a view for explaining gaps between the journal 2 and the pads 31 _, 3 _{2 ′} , and 3 _{6 ′} . As shown in FIG. 12, when the journal 2 actually rotates, the journal 2 descends to a position where the oil film force formed in the gap between the journal 2 and the pad and the weight of the journal 2 are balanced. In this case, the center of the journal 2 moves from O1 to O2 which is eccentric by the eccentric amount e, and the journal 2 is in a state indicated by reference numeral 2 ′. The gaps h1, h2, and h6 formed between the journal 2 ′ and each pad are expressed by Expression (8).

here,

Represents the eccentricity. Φ is the basis of the straight line O1-O2, as shown in FIG. 12 shows the circumferential angle from the straight line O1-O2 to the gap of the second pad 3 _{2 'of} interest. As shown in Expression (8), the relationship of gap h1 <h2 = h6 is established. That is, the bearing oil film force becomes larger as the gap is small, Calalou bearing oil film force becomes largest in the first pad 3 _1.

Further, as shown by the equation (6), the deformation amount δ increases by reducing the circumferential radius of curvature R1 ′. That is, the gap C ′ is increased by reducing the circumferential curvature radius R1 ′. As a result, as shown in Expression (8), h1 is further reduced as compared with h2 and h6, and the eccentricity ε of the pad 1 is increased. As it can be seen from this that, by a smaller circumferential radius of curvature R1 ', load on the first pad 3 ₁ is more increased, the anisotropy of the bearing oil film force by oil film strength in the vertical direction is increased Will increase.

(effect)
As described above, according to the tilting pad journal bearing 100 according to the present embodiment, than the circumferential radius of curvature firing angle of the pad back to the first pad 3 ₁ arranged beneath the vertical direction, the first pad 3 ₁ it was decided to reduce the circumferential curvature radius arc angle of the pad back in the horizontal second pad 3 _{2 ',} and the third pad 3 _6' which is the direction in disposed adjacent to both sides. Thus, by front and journal second gap of the second pad 3 _{2 ',} and the third pad 3 _6' widens more, it is possible to further increase the anisotropy of the bearing oil film force, instability of the working fluid It is possible to prevent the occurrence of unstable vibration due to the chemical force.

(Eighth embodiment)
The tilting pad journal bearing according to the eighth embodiment further increases the anisotropy of the bearing oil film force by providing a taper portion at the rear end of the pad in the second and third pads arranged in the horizontal direction. By trying to prevent unstable vibrations from occurring. Hereinafter, a different part from 1st Embodiment mentioned above is demonstrated.

(Constitution)
The pads 3 _{2 ′} and 3 _{6 ′} according to the eighth embodiment will be described based on FIG. 13, the pad 3 _{2 'according} to the eighth embodiment, is a diagram illustrating the shape of 3 _6. As shown in this FIG. 13, by providing the second pad 3 _{2 ',} and the tapered portion 11 at an end portion of the pad behind the rotational direction of the journal of the third pad 3 ₆ disposed horizontally, Different from the first to seventh embodiments.

(Function)
As described above, by providing the tapered portion 11 at the rear end of the pads 3 _{2 ′} and 3 _{6 ′} , the oil film pressure is not generated in the range of the tapered portion 11, and the second pads 3 arranged in the horizontal direction. _The load on the entire _{2 '} and third pads 36 _' is also reduced. That is, the oil film force in the horizontal direction is reduced and the anisotropy of the bearing oil film force can be increased. Further, by adjusting the inclination of the taper portion 11, it is possible to adjust the flow of the working fluid, that is, the lubricating oil.

(effect)
As described above, according to the tilting pad journal bearing 100 of this embodiment, the second pad 3 ₂ disposed horizontally adjacent to the first sides of the pad 3 _{1 'and} the third pad 3 _6' The tapered portion 11 is provided at the rear end. As a result, the anisotropy of the bearing oil film force increases, it is possible to prevent the occurrence of unstable vibration due to the destabilizing force from the working fluid, and it is possible to adjust the flow of the lubricating oil.

(Ninth embodiment)
The tilting pad journal bearing according to the ninth embodiment further increases the anisotropy of the bearing oil film force by providing a tapered portion at the front end of the pad in the second and third pads arranged in the horizontal direction. By trying to prevent unstable vibrations from occurring. Hereinafter, a different part from 1st Embodiment mentioned above is demonstrated.

(Constitution)
The pads 3 _{2 ′} and 3 _{6 ′} according to the ninth embodiment will be described with reference to FIG. FIG. 14 is a diagram illustrating the shapes of the pads 3 _{2 ′} and 3 _{6 according} to the ninth embodiment. As shown in this FIG. 14, the second pad 3 ₂ disposed horizontally _', third pad 3 _6' by providing the tapered portion 2 at an end portion of the pad forward with respect to the rotational direction of the journal, Different from the first to eighth embodiments.

(Function)
As described above, by providing the tapered portion 12 at the front ends of the pads 3 _{2 ′} and 36 _′ , the oil film pressure is not generated in the range of the tapered portion 12 as in the eighth embodiment, and is arranged in the horizontal direction. has been the second pad 3 _{2 ',} the load is also reduced according to the whole of the third pad 3 _6. As a result, the oil film force in the horizontal direction is reduced, and the anisotropy of the bearing oil film force can be increased. Furthermore, the lubricating oil of the bearing flowing into the gap between the journal 2 and the pads 3 _{2 ′} and 3 _{6 ′} easily enters the gap by the taper 12, leading to a reduction in the risk of running out of the bearing oil film.

(effect)
As described above, according to the tilting pad journal bearing 100 of this embodiment, the second pad 3 ₂ disposed horizontally adjacent to the first sides of the pad 3 _{1 'and} the third pad 3 _6' The taper portion 12 is provided at the front end of the head. As a result, the anisotropy of the bearing oil film force increases, it is possible to prevent the occurrence of unstable vibration due to the destabilizing force from the working fluid, and the fluid flows into the gap between the journal 2 and the pads 3 _{2 ′} and 3 _{6 ′.} It is possible to increase the lubricating oil of the bearing.

(10th Embodiment)
The tilting pad journal bearing according to the tenth embodiment provides anisotropy of the bearing oil film force by providing tapered portions at the front and rear end portions of the second and third pads arranged in the horizontal direction. It is intended to prevent the occurrence of unstable vibrations by increasing the number. Hereinafter, a different part from 1st Embodiment mentioned above is demonstrated.

(Constitution)
The pads 3 _{2 ′} and 3 _{6 ′} according to the tenth embodiment will be described based on FIG. FIG. 15 is a view for explaining the shapes of the pads 3 _{2 ′} and 3 _{6 ′ according} to the tenth embodiment. As shown in FIG. 15, provided the second pad 3 _{2 ',} third pad 3 _6' tapered portions 13 and 14 to the ends of the pad forward and backward with respect to the rotational direction of the journal, which is arranged in the horizontal direction This is different from the first to ninth embodiments.

(Function)
As described above, the pad 33 2 _', 3 _6' by providing the tapered portion 13 at the front end of, similarly to the ninth embodiment, the journal 2 and the pad 3 _{2 ',} 3 _6' of the bearing from flowing into the gap The lubricating oil easily enters the gap due to the taper 13 and leads to a reduction in the risk of running out of the bearing oil film.

Furthermore, the oil film pressure is not generated within a range of the tapered portion 13 and 14, left and right pads 3 _{2 ',} 3 _6' load on the whole is also reduced, the anisotropy of the horizontal oil film force decreases and the bearing oil film force Can be increased.

(effect)
As described above, according to the tilting pad journal bearing 100 of this embodiment, the second pad 3 ₂ disposed horizontally adjacent to the first sides of the pad 3 _{1 'and} the third pad 3 _6' The tapered portions 13 and 14 are provided at the front end and the rear end. Thus, with the increase in the anisotropy of the bearing oil film force, the journal 2 and the pad 3 _{2 ',} 3 _6' clearance bearing lubricating oil can increase the flowing in of, and adjustment of the flow direction of the lubricating oil Is also possible.

(Eleventh embodiment)
The turbo machine according to the eleventh embodiment is intended to prevent the occurrence of unstable vibration in the turbine rotor by supporting the journal with a tilting pad journal bearing in which the anisotropy of the bearing oil film force is further increased. is there. More details will be described below.

(Constitution)
An example of the turbo machine in the present embodiment will be described based on FIG. FIG. 16 is a view showing a cross section (meridian cross section) including the axis X of the turbine rotor 32 of the steam turbine 30. As shown in FIG. 16, a steam turbine 30 that is an example of a turbo machine includes a casing 32, a turbine rotor 34, and a tilting pad journal bearing 100. The casing 32 seals the working steam. The turbine rotor 34 has an axial line along the horizontal direction, and includes a turbine rotor 36 and a rotor blade cascade 38. The turbine rotor 36 passes through the casing 32 so as to be freely rotatable. The rotor blade cascade 38 is provided in the turbine rotor 36. A plurality of stationary blade cascades 40 are provided in the casing 32, and are arranged alternately with the moving blade cascades 38 in the axial direction of the turbine rotor 34. The steam turbine 30 according to the present embodiment is placed horizontally, and the axis of the turbine rotor 32 is in the horizontal direction. The tilting pad journal bearing 100 rotatably supports the journal of the turbine rotor 36 with respect to the casing 32. That is, the tilting pad journal bearing 100 is a tilting pad journal bearing according to any one of the first to tenth embodiments.

(Function)
Since the journal of the turbine rotor 36 is supported by the tilting pad journal bearing 100 with increased bearing oil film force anisotropy, unstable vibration of the turbine rotor 36 is suppressed.

(effect)
As described above, in the turbo machine according to the present embodiment, the journal of the turbine rotor 36 is supported by the tilting pad journal bearing 100 in which the anisotropy of the bearing oil film force is increased. Accordingly, it is possible to prevent the occurrence of unstable vibration due to the destabilizing force from the working fluid, and it is possible to provide a turbo machine that further suppresses the unstable vibration.

  Although several embodiments have been described above, these embodiments are presented as examples only and are not intended to limit the scope of the invention. The novel apparatus described herein can be implemented in various other forms. Various omissions, substitutions, and changes can be made to the form of the apparatus described in the present specification without departing from the gist of the invention. The appended claims and their equivalents are intended to include such forms and modifications as fall within the scope and spirit of the invention.

2: _Journal, 3 _{1, 3 2,} 3 3 ... _{3 6,} 3 _{1 ',} 3 _2', 3 _{6 ':} Pad, 4: bearing inner _ring, 5 _{1, 5 2,} 5 3 ... _{5 6} : Pivot, 6: Pad oil hole, 30: Steam turbine, 32: Casing, 34: Turbine rotor, 36: Turbine rotor, 38: Rotor blade cascade, 40: Stator blade cascade, 100: Tilting pad journal bearing

Claims (11)

In a tilting pad journal bearing in which a plurality of arc-shaped pads are incorporated in the inner ring of the bearing so as to be swingable around a support point on the back of the pad,
Among the plurality of pads, the arc angle of the second pad and the third pad arranged in the horizontal direction adjacent to both sides of the first pad is larger than the arc angle of the first pad arranged directly below the vertical direction. Tilting pad journal bearing characterized by being small.   The tilting pad journal bearing according to claim 1, wherein the axial lengths of the second pad and the third pad are shorter than the axial length of the first pad.   3. The tilting according to claim 1, wherein the vertical direction is a load direction of a journal supported by the plurality of pads, and the first pad is a pad that receives the load of the journal most. Pad journal bearing.   4. The tilting pad journal bearing according to claim 3, wherein a lubricating oil supply hole is provided at a front end portion of the first pad with respect to a rotation direction of the journal. 5. In a tilting pad journal bearing in which a plurality of arc-shaped pads are incorporated in the inner ring of the bearing so as to be swingable around a support point on the back of the pad,
The tilting pad journal bearing characterized in that an arc angle of a pad in a pad that receives the most load of a journal supported by the plurality of pads is larger than an arc angle of other pads in the plurality of pads. In a tilting pad journal bearing in which a plurality of arc-shaped pads are incorporated in the inner ring of the bearing so as to be swingable around a support point on the back of the pad,
A tilting pad journal bearing, wherein an axial length of a pad that receives the load of a journal supported by the plurality of pads is longer than an axial length of other pads in the plurality of pads.   2. The tilting pad journal bearing according to claim 1, wherein a circumferential curvature radius of the pad back surface of the second pad is smaller than a circumferential curvature radius of the pad back surface of the first pad.   The tilting pad journal bearing according to claim 1, wherein a taper is provided at a rear end portion with respect to a rotation direction of the journal of the second pad. The tilting pad journal bearing according to claim 1, wherein a taper is provided at a front end portion with respect to a rotation direction of the journal of the second pad.   2. The tilting pad journal bearing according to claim 1, wherein a taper is provided at front and rear ends with respect to a rotation direction of the journal of the second pad. Turbine rotation having a casing in which a plurality of stationary blade cascades are arranged, a turbine rotor rotatably passing through the casing, and a plurality of rotor blade cascades provided in the turbine rotor and alternately arranged with the stationary blade cascades And a tilting pad journal bearing that rotatably supports a journal of the turbine rotor with respect to the casing, wherein the tilting pad journal bearing has an arc shape inside a bearing inner ring. A tilting pad journal bearing that incorporates a plurality of pads so as to be swingable around a support point on the back of the pad,
Among the plurality of pads, the arc angle of the second pad and the third pad arranged in the horizontal direction adjacent to both sides of the first pad is larger than the arc angle of the first pad arranged directly below the vertical direction. A turbomachine characterized by being small.

Images