JP2008151239A - Tilting pad type bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tilting pad type bearing capable of surely inhibiting a rise of pad temperature due to a carry-over phenomenon with a simple construction. <P>SOLUTION: The tilting pad type bearing 10 for supporting a rotary shaft 1 through a tilting pad 11A which is circumferentially divided and tiltable is provided with a bypass flow path 30 for introducing a part of lubrication oil from a high temperature region of the tilting pad 11A and letting it out. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a tilting pad type bearing that supports a rotating shaft of a large rotating machine such as a turbine or a generator, such as a sliding bearing of a steam turbine.

Conventionally, in large rotating machines such as turbines and generators, for example, tilting pad type bearings (hereinafter referred to as “bearings”) 10 as shown in FIG. 8 are used to support the rotating shaft. .
The bearing 10 includes a plurality of tilting pads (hereinafter referred to as “pads”) 11 which are disposed in a bearing housing 12 and can swing (tilt) about a pivot 13. A wedge-shaped oil film is formed between the surfaces 15. The bearing 10 is excellent in vibration stability because the center of the shaft is eccentric in the load direction, and is widely used in high-speed rotating machines.

  In such a bearing 10, the temperature rise of the pad 11 due to the carry-over phenomenon limits the load capacity of the bearing. The carry-over phenomenon is that the lubricating oil Lh that forms a lubricating film on the pad 11 disposed on the upstream side in the rotational direction of the rotary shaft 1 between the pads 11 that are divided into a plurality of portions in the circumferential direction. This is a phenomenon of flowing into the pad 11 on the downstream side without being sufficiently cooled between the adjacent pads 11 while maintaining a high temperature. As a result, the low temperature lubricating oil Lc supplied to the downstream pad 11 is mixed with the high temperature hydraulic oil Lh flowing from the upstream side, and the initial temperature supplied to the inlet of the inter-surface 15 increases.

As a countermeasure for preventing the carry-over phenomenon of the thrust bearing described above, a method of inserting a scraper between the pads has been proposed. (For example, see Patent Document 1)
In the tilting pad type bearing, it has been proposed to provide a notch in the pad on the anti-load side in order to generate an appropriate pressure on the pad on the anti-load side to prevent the pad from swinging. (For example, see Patent Document 2)
JP 2004-108491 A JP 2004-301258 A

However, because the scraper and collar are in contact with each other as described above, the scraper and collar are in contact with each other, so there is a problem of torque that becomes a rotational load due to friction between both parts, and a problem of shortening the service life due to wear of the contact part. Has been pointed out.
Further, when a non-contact type scraper is employed as a solution to the above-described problem, it is necessary to position the upper end of the scraper at the radial position of the pad trailing edge and the gap between the journals (for example, about several tens of μm). For this reason, although it is considered that a non-contact type scraper is theoretically established, it is estimated that it is extremely difficult to realize the position control of the scraper which will be about several μm with an inexpensive and simple configuration.
Further, at the time of start-up, if the upper end of the scraper is not located outside the radial position of the pad trailing edge, the scraper may come into contact with the journal. Therefore, it is necessary to be located inside the pad trailing edge during operation. For this reason, since the scraper needs to have a mechanism movable in the radial direction, there arises a problem of complicating the apparatus.

As described above, in the tilting pad type bearing, in order to increase the bearing load capacity, it is desired to reliably suppress an increase in the pad temperature due to the carry-over phenomenon with a simple structure.
The present invention has been made in view of the above circumstances, and an object thereof is to provide a tilting pad type bearing that can reliably suppress an increase in pad temperature due to a carry-over phenomenon with a simple structure. There is to do.

In order to solve the above problems, the present invention employs the following means.
The present invention is a tilting pad type bearing that supports a rotating shaft via a tilting pad that is divided in the circumferential direction and is tiltable.
A bypass flow path for introducing a part of the lubricating oil from the periphery of the high temperature region of the tilting pad and flowing it out is provided.

  According to such a tilting pad type bearing, since the bypass flow path for introducing a part of the lubricating oil from the periphery of the high temperature region of the tilting pad and flowing out is provided, the high temperature flowing into the tilting pad on the downstream side is provided. Part of the lubricating oil flows out of the bypass flow path and decreases. For this reason, in the downstream tilting pad, it is possible to suppress a carry-over phenomenon in which the temperature rises as a result of the high temperature lubricating oil flowing into the newly supplied low temperature lubricating oil from the upstream side.

In the above invention, the bypass flow path is provided through the inside of the tilting pad from the inlet opening around the high temperature region to the outlet opening near the downstream pad oil supply section. It is preferable that the carryover phenomenon occurring in the downstream tilting pad can be suppressed.
In this case, it is preferable that the outlet opening opened in the vicinity of the downstream pad oil supply part allows high-temperature lubricating oil to flow out from the nozzle of the oil supply part toward the outer peripheral side.

In the above invention, it is preferable that the pad side wall surface forming the inlet gradually increases in the circumferential direction, whereby a smooth channel can be formed on the channel lower surface side. For this reason, since the flow velocity distribution on the lower surface side from the upper surface side of the flow path is expanded, the amount of lubricating oil introduced into the bypass flow path can be increased.
In the above invention, the introduction port is preferably formed in a divergent inlet shape with the upstream side expanded in the axial direction, thereby increasing the amount of lubricating oil introduced into the bypass flow path by expanding the inlet. Can do.

In the above invention, the bypass flow path is provided near the high temperature region and gradually increases in depth in the circumferential direction, and from the inlet opening to the inside of the weir to the vicinity of the downstream pad oil supply portion. It is preferable to provide an oil passage hole provided through the tilting pad to the outlet port that opens, and thereby, the hot lubricating oil that has flowed into the lower part of the weir is actively passed from the oil hole. Can be drained.
In this case, the weir is preferably provided with at least a part of the pad width left in the direction of the rotation axis of the tilting pad, so that the inter-surface pressure can be secured even on the downstream side of the weir.

  In the above invention, the weir is preferably formed in a divergent inlet shape with the upstream side widened in the axial direction, whereby the inlet of the weir spreads and the amount of lubricating oil introduced into the bypass channel is increased. be able to.

According to the present invention described above, the bypass flow path for introducing a part of the lubricating oil from the periphery of the high temperature region where the oil temperature is highest in the tilting pad is provided, so that the high temperature flowing into the downstream tilting pad. A part of the lubricating oil flows out of the bypass channel and decreases. For this reason, in the downstream tilting pad, it becomes possible to suppress the carry-over phenomenon in which the high temperature lubricating oil flows into the newly supplied low temperature lubricating oil from the upstream side and the temperature rises. The remarkable effect of increasing the bearing load capacity of the tilting pad type bearing is obtained by the suppression.
In addition, the bypass flow path of the present invention can be reliably realized with a simple structure in which the tilting pad is machined, so that not only the addition of new parts is unnecessary, but also an existing bearing using the tilting pad. Can be easily applied.

Hereinafter, an embodiment of a tilting bearing according to the present invention will be described with reference to the drawings.
FIG. 4 is a cross-sectional view showing a schematic configuration of the tilting type bearing. The illustrated tilting bearing (hereinafter referred to as “bearing”) 10 includes a plurality of tilting pads (hereinafter referred to as “pads”) 11 that support the rotating shaft 1 from the periphery. The pad 11 is arranged to be divided into four in the circumferential direction inside the bearing housing 12, but the number of divisions is not particularly limited. Further, the outer peripheral surface of each pad 11 is supported on the inner peripheral surface of the bearing housing 12 via a pivot 13 so as to be swingable. That is, the bearing 10 is divided in the circumferential direction and is configured to support the rotating shaft 1 via the pad 11 that can be tilted (oscillated).

  The bearing 10 described above includes an oil supply nozzle 20 as an oil supply part that supplies lubricating oil in the vicinity of each tilting pad 11. The oil supply nozzle 20 supplies oil toward the tilting pad 11 in the direction in which the rotary shaft 1 rotates. In the following description, the direction in which the rotating shaft 1 rotates is referred to as the downstream side. Therefore, each oil supply nozzle 20 supplies the lubricating oil to the tilting pad 11 located on the downstream side. By performing such oil supply, a wedge-shaped oil film is formed by the lubricating oil moving from the upstream side to the downstream side between the surfaces 15 of the rotating shaft 1 and the tilting pad 11.

<First Embodiment>
Hereinafter, a first embodiment of a tilting bearing according to the present invention will be described with reference to FIGS. 1 and 2.
The pad 11 </ b> A of this embodiment includes a bypass flow path 30 that introduces a part of lubricating oil from the periphery of the high-temperature region 15 between the faces 15 and flows it out. Here, the high temperature region is a region where the lubricating oil supplied from the oil supply nozzle 20 located on the upstream side and flowing out through the space 15 to the downstream side becomes the highest temperature. That is, the lubricating oil forming the oil film rises in temperature in the process of moving between the surface 15 between the rotating shaft 1 and the pad 11A from the upstream inlet 15a to the downstream outlet 15b. 11A downstream end) 15b vicinity is the high temperature region where the oil temperature has risen the most.

The bypass flow path 30 described above is linearly provided through the pad 11 </ b> A from the inlet 31 that opens in the vicinity of the high temperature region to the outlet 32 that opens in the vicinity of the downstream pad oil supply nozzle 20. . For example, as shown in FIG. 2 (a), a plurality of bypass channels 30 may be arranged in parallel in the width direction of the pad 11A at an equal pitch, or as shown in FIG. 2 (b). Alternatively, a wide one may be provided.
In particular, the outlet 32 of the bypass passage 30 prevents or suppresses mixing with low-temperature lubricating oil that flows out from the downstream pad oil supply nozzle 20 and is supplied to the inter-surface 15, and for the downstream pad. In order to prevent the lubricating oil from flowing backward from the oil supply nozzle 20, the opening is preferably directed toward the bearing housing 12 on the outer peripheral side from the outlet of the oil supply nozzle 20. Such a bypass flow path 30 can be easily formed by machining the pad 11A, so there is no need to add new parts and the like, and therefore it is easily adopted including remodeling the existing bearing 10. It becomes possible.

  As a result, the lubricating oil flowing through the inter-surface 15 is partially introduced into the bypass passage 30 from the inlet 31 that opens near the high temperature region where the oil temperature is highest. For this reason, since the amount of high-temperature lubricating oil that flows through the inter-surface 15 and flows out from the downstream outlet 15b toward the downstream pad 11A decreases, the low-temperature lubricating oil supplied to the downstream pad 11A The temperature rise of the initial temperature is suppressed by reducing the mixing amount with the lubricating oil. That is, in the low-temperature lubricating oil supplied from the oil supply nozzle 20, the carry-over phenomenon that increases in temperature due to mixing with the high-temperature lubricating oil flowing from the upstream pad 11A is suppressed.

  Further, since the above-described high temperature region is on the downstream side from the maximum pressure position in the inter-surface 15, there is no fatal effect that the formation of the bypass flow path 30 reduces the load capacity of the bearing 10. That is, since the introduction port 31 of the bypass channel 30 is in a position that does not overlap with the position where the pressure is highest in the inter-surface 15, the pressure difference between the introduction port 31 and the outflow port 32 that becomes atmospheric pressure is relatively small, and therefore The amount of lubricating oil that flows out from the inlet 31 to the bypass passage 31 can be secured by leaving a sufficient amount of the oil film formed on the downstream side of the inlet 31.

  Moreover, it is preferable that the inlet 31 of the bypass flow path 30 described above is formed so that the wall surface on the pad 11A side gradually increases in the outer peripheral direction. Specifically, the pad side wall surface 31a of the introduction port 31 for introducing the lubricating oil from the inter-surface 15 into the bypass channel 10 is formed in a smooth curved surface shape without corners. Such an introduction port 31 is used to expand the velocity distribution on the lower surface side of the flow channel guided to the bypass flow channel 30 rather than the upper surface side of the flow channel 15 between the planes 15 that reach the downstream side outlet 15b. Compared with the bypass passage 30 having a corner at 31, the ratio of the amount of lubricating oil introduced into the bypass passage 30 can be increased.

  In addition, in the modification shown in FIG. 3, the inlet 31A is formed in a divergent inlet shape with the upstream side expanded in the axial direction. That is, the inlet 31A of the pad 11A has a groove shape in which the inlet width W on the upstream side is gradually narrower than the bypass channel 30 as viewed from the direction of the arrow A (see FIG. 1A). Therefore, the amount of lubricating oil introduced into the bypass channel 30 can be increased compared to the above-described embodiment.

<Second Embodiment>
Next, a second embodiment of the tilting type bearing according to the present invention will be described with reference to FIGS. In addition, the same code | symbol is attached | subjected to the part similar to embodiment mentioned above, and the detailed description is abbreviate | omitted.
The pad 11B of this embodiment includes a weir 40 in which a bypass channel 30A is provided in the vicinity of the high temperature region and gradually increases in depth from the upstream side to the downstream side in the circumferential direction, and is introduced into the inside of the weir 40 An oil passage hole 50 provided through the pad 11B is provided from the opening 31A to the outlet 32A that opens in the vicinity of the oil supply nozzle 20 that is the oil supply section for the pad on the downstream side. The pad 11 </ b> B configured as described above is disposed over the entire circumference of the rotating shaft 1.

  In this case, the vicinity of the oil supply nozzle 20 where the outflow port 32 </ b> A is open means a range in which mixing with the low-temperature lubricating oil supplied from the oil supply nozzle 20 is completely absent or minimized. More specifically, for example, in the configuration example shown in FIG. 5B, the oil passage hole 50 that opens the outlet 32A is formed at both side ends of the pad 11B in the axial direction of the rotary shaft 1, and the high-temperature lubrication that has flowed out. Oil is prevented from mixing with the lubricating oil supplied from the oil supply nozzle 20. Further, in the configuration example shown in FIG. 6B, the oil supply nozzle 20 is supplied by forming the oil passage hole 50 inclined obliquely toward the outflow port 32 </ b> A opening on the downstream side in the circumferential direction of the pad 11 </ b> B. Prevents mixing with lubricating oil.

  By the way, in the above-described embodiment, if the weir 40 is provided over the entire width in the axial direction of the pad 11B, a problem occurs in the formation of the oil film on the downstream side. Therefore, it is necessary to leave at least a part of the pad surface on which the weir 40 is not provided. is there. As a result, the necessary inter-surface pressure can be ensured between the rotating shaft 1 and the pad 11B also on the downstream side of the weir 40. Further, at the time of starting the rotating shaft 1, there is no possibility that the rotating shaft 1 is damaged due to interference with the stepped portion of the weir 40.

  With such a configuration, the lubricating oil that moves in the inter-surface 15 from the inlet 15a to the outlet 15b to form an oil film flows into the weir 40 around the high temperature region. The lubricating oil flows into the oil passage hole 50 from the inlet 31A that opens into the weir 40, and flows out from the outlet 32A to the vicinity of the oil supply nozzle 20 through the oil passage hole 50. Therefore, by providing the weir 40, the high-temperature lubricating oil that has flowed into the weir 40 can be actively discharged from the oil hole 50.

In the modification shown in FIG. 7, the weir 40 </ b> A is formed in a divergent inlet shape with the upstream side expanded in the axial direction. That is, the weir 40A has a groove shape in which the inlet width W on the upstream side is gradually wider and narrower than the weir 40A in the same manner as the introduction port 31A described above. The amount of lubricating oil introduced into 40A can be increased.
As described above, the weirs 40 and 40A of the present embodiment are different from the prior art in which the anti-load side pad is prevented from swinging in the circumferential direction (fluttering). The lubricant is discharged to reduce the carry-over phenomenon.

According to the present invention described above, the bypass passages 30 and 30A for introducing a part of the lubricating oil and flowing out from the periphery of the high temperature region where the oil temperature of the lubricating oil is highest in the pads 11A and 11B are provided. Part of the high-temperature lubricating oil flowing into the side pads 11A and 11B flows out of the bypass flow paths 30 and 30A and decreases. For this reason, in the pads 11A and 11B on the downstream side, the carry-over phenomenon in which the high temperature lubricating oil flows into the newly supplied low temperature lubricating oil from the upstream side and the temperature rises can be reliably suppressed with a simple structure. The bearing load capacity of the bearing 10 can be increased by suppressing the pad temperature.
In addition, this invention is not limited to embodiment mentioned above, In the range which does not deviate from the summary of this invention, it can change suitably.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows 1st Embodiment of the tilting pad type | mold bearing which concerns on this invention, (a) is sectional drawing which shows the structure of the principal part, (b) is an enlarged view of a bypass flow path periphery. FIGS. 1A and 1B are views as viewed from an arrow A, in which FIG. 1A is a configuration example in which a plurality of bypass channels are provided, and FIG. It is A arrow line view which shows the modification of 1st Embodiment. It is sectional drawing which shows the schematic structural example of a tilting pad type | mold bearing. It is a figure which shows 2nd Embodiment of the tilting pad type bearing which concerns on this invention, (a) is sectional drawing which shows the structure of the principal part, (b) is a B arrow view of (a). 6A and 6B are views showing a first modification of FIG. 5, in which FIG. 5A is a cross-sectional view showing a configuration of a main part, and FIG. FIG. 6 is a B arrow view showing a second modification of FIG. 5. It is explanatory drawing of the carry over phenomenon in the conventional tilting pad type | mold bearing.

Explanation of symbols

1 Rotating shaft 10 Tilting pad type bearing (bearing)
11A, 11B Tilting pad (pad)
12 Bearing housing 13 Pivot 20 Oil supply nozzle 30, 30A Bypass flow path 40 Weir 50 Oil passage hole

Claims (6)

A tilting pad type bearing that supports a rotating shaft via a tilting pad that is divided in the circumferential direction and is tiltable.
A tilting pad type bearing comprising a bypass flow path for introducing a part of lubricating oil from a periphery of a high temperature region of the lubricating surface of the tilting pad.   The bypass passage is an oil passage hole provided through the inside of the tilting pad from an inlet opening around the high temperature region to an outlet opening near the downstream pad oil supply portion. The tilting pad type bearing according to claim 1.   The tilting pad type bearing according to claim 2, wherein the side wall surface of the pad forming the introduction port gradually increases in the circumferential direction.   The tilting pad type bearing according to claim 2 or 3, wherein the introduction port is formed in a shape of a divergent inlet having an upstream side expanded in the axial direction.   The bypass channel is provided around the high temperature region and gradually increases in depth in the circumferential direction, and from the inlet opening in the weir to the outlet opening in the vicinity of the downstream pad oil supply unit The tilting pad type bearing according to claim 1, further comprising an oil passage hole penetrating through the tilting pad.   6. The tilting pad type bearing according to claim 5, wherein the weir is formed in a divergent inlet shape in which the upstream side is expanded in the axial direction.

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