JP2017026089A - Tilting pad journal bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tiling pad journal bearing of high reliability capable of improving lubrication oil supply efficiency while preventing increase of a lubrication oil film temperature even when a lubrication oil supply amount is small, by reducing an amount of the lubrication oil discharged without entering a lubrication oil film, with respect to the lubrication oil supplied from oil supply means.SOLUTION: In a tiling pad journal bearing including a plurality of pads 2 slidably disposed at an outer peripheral side of a rotating shaft, and a plurality of lubrication oil supply means 3 disposed among the plurality of pads 2 for directly supplying lubrication oil respectively between an outer peripheral face of the rotating shaft and an inner peripheral face of the pad 2, a peripheral position of a front edge of a sliding face 7 of the pad 2 has a part gradually retracted from the center in the axial direction toward a shaft end portion.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a tilting pad journal bearing used in a high-speed rotating machine such as a centrifugal compressor.

  In a high-speed rotating machine such as a centrifugal compressor, for example, a tilting pad journal bearing as shown in Non-Patent Document 1 is used. This tilting pad journal bearing has a plurality of pads disposed on the outer peripheral side of the rotating shaft and provided so as to be swingable. Then, by forming an oil film between the inner peripheral surfaces of the plurality of pads (hereinafter referred to as a sliding portion), it is possible to bear the radial load of the rotating shaft while preventing contact between the rotating shaft and the pad. It has become.

  Tilting pad journal bearings can be roughly divided into two types depending on the lubrication method. One is called an oil bath method, in which the pad storage space of the housing is filled with lubricating oil and the sliding portion is immersed. The other is called a direct lubrication system, which does not fill the pad storage space of the housing with lubricating oil, and directly supplies the lubricating oil to the sliding part by a plurality of nozzles arranged between the pads. (For example, see Patent Document 1). Compared with the oil bath method, this direct lubrication method can supply relatively low temperature oil to the sliding portion, and since the temperature of the sliding portion can be easily lowered, the amount of oil supply can also be relatively reduced. There are merits such as.

JP 2004-197890 A

(Japan) Tribology Society of Japan, Tribology Handbook, Yokendo (2001), p53-57

  In direct lubrication type tilting pad bearings, it is ideal that all the lubricating oil supplied from the oil supply means is guided to the oil film, but in reality, the lubricating oil flowing into the oil film is a part, and the remaining part Had a problem of being discharged without entering the oil film.

  The object of the present invention is to improve the oil supply efficiency by reducing the amount of lubricating oil supplied from the oil supply means that is discharged without entering the oil film, and the oil film temperature does not increase even with a small oil supply amount. It is to provide a high tilting pad journal bearing.

  The tilting pad journal bearing is disposed on the outer peripheral side of the rotating shaft and is provided between the plurality of pads provided so as to be able to swing, and the outer peripheral surface of the rotating shaft and the inner periphery of the pad. In a tilting pad journal bearing having a plurality of oil supply means for directly supplying oil to the surface, the circumferential position of the leading edge of the sliding surface of the pad recedes from the axial center to the shaft end. It has the part to do.

  According to the present invention, the sliding surface temperature can be reduced without increasing the amount of oil supplied from the nozzle.

It is sectional drawing showing the structure of the tilting pad journal bearing in the 1st Embodiment of this invention. It is a perspective view showing the structure of the pad in the 1st Embodiment of this invention with the oil supply means. It is a perspective view showing the flow of the oil in the 1st Embodiment of this invention with the structure of a pad, and oil supply means. It is a perspective view showing the structure of the pad 2 in the 2nd Embodiment of this invention with an oil supply means. It is a perspective view showing the structure of the pad in the 3rd Embodiment of this invention with the oil supply means.

The present invention will be described below.
(1) The present invention provides a plurality of pads disposed on the outer peripheral side of the rotary shaft and provided so as to be swingable, and provided between the plurality of pads. The outer peripheral surface of the rotary shaft and the inner periphery of the pad In a tilting pad journal bearing having a plurality of oil supply means for directly supplying oil to the surface, the circumferential position of the leading edge of the sliding surface of the pad recedes from the axial center to the shaft end. It has a part to do.

  As described above, in the present invention, a part of the lubricating oil supplied from the oil supply means is supplied to the oil film at the same axial position. The lubricating oil that has not fully entered the oil film at the same axial position as the oil supply means flows to the oil film after flowing in the axial direction along the leading edge of the sliding surface that retreats toward the end in the axial direction. . As a result, the low-temperature lubricating oil supplied from the oil supply means can be introduced into a wide oil film in the axial direction without flowing out, and the sliding surface temperature can be reduced.

  As described above, in the present invention, the sliding surface temperature can be reduced without increasing the amount of oil supplied from the nozzle.

  (2) In the above (1), preferably, an inlet groove is provided on the upstream side of the leading edge of the sliding surface of the pad, and the inlet groove is opened on the upstream side and the axial direction side.

  (3) In the above (2), preferably, the inlet groove is provided on the upstream side of the most upstream portion of the leading edge of the sliding surface of the pad.

  (4) In any one of the above (1) to (3), preferably, the most upstream portion of the leading edge of the sliding surface of the pad is partially linear in the axial direction.

  (5) In any one of the above (2) to (4), the depth of the inlet groove is preferably shallower toward the downstream.

Embodiments according to the present invention will be described below with reference to the drawings.
(First embodiment)
A first embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 is a cross-sectional view showing the structure of a tilting pad journal bearing in the present embodiment. FIG. 2 is a perspective view illustrating the structure of the pad according to the present embodiment together with the oil supply means.

  1 and 2, the tilting pad journal bearing is arranged on the outer peripheral side of the rotating shaft 1 and is supported by the pivot 4 so as to be swingable, for example, five pads 2a to 2e (hereinafter referred to as appropriate). ), Five oil supply means 3a-3e (hereinafter referred to as “oil supply means 3” as appropriate) provided between these pads 2a-2e, and pads 2a-2e. And a casing 5 for housing the nozzles 3a to 3e and the like. In the present embodiment, the rotating shaft 1 extends in the horizontal direction, and the pads 2 a and 2 e are positioned above the rotating shaft 1. Moreover, the rotating shaft 1 is rotating in the rotation direction shown by the arrow R in FIG.

  Lubricating oil is not filled in the pad storage space of the housing 5, and the lubricating oil is supplied to the oil supplying means 3 a to 3 e through an annular oil supply passage (not shown) formed on the outer peripheral side of the housing 5. The The oil from the oil supply port at the tip of the oil supply means 3a is directly supplied between the outer peripheral surface of the rotary shaft 1 and the inner peripheral surface of the pad 2a, and the oil from the oil supply port at the tip of the oil supply means 3b is supplied to the rotary shaft 1. Is directly supplied between the outer peripheral surface of the rotary shaft 1 and the inner peripheral surface of the pad 2b, and oil from the oil supply port at the tip of the oil supply means 3c is directly supplied between the outer peripheral surface of the rotary shaft 1 and the inner peripheral surface of the pad 2c. The oil from the oil supply port at the tip of the oil supply means 3d is directly supplied between the outer peripheral surface of the rotary shaft 1 and the inner peripheral surface of the pad 2d, and the oil from the oil supply port at the tip of the oil supply means 3e is supplied to the rotary shaft 1. It is supplied directly between the outer peripheral surface and the inner peripheral surface of the pad 2e. As a result, relatively low temperature oil can be supplied between the outer peripheral surface of the rotating shaft 1 and the inner peripheral surface of the pad 2, and the amount of oil supplied can be relatively reduced.

  When the rotary shaft 1 rotates, oil is caught between the outer peripheral surface of the rotary shaft 1 and the inner peripheral surface of the pad 2 to form an oil film. The rotating shaft 1 is lifted by the pressure generated in the oil film, and is supported without being in direct contact with the pads 2a to 2e.

  Here, as a major feature of the present embodiment, the inlet side edge 8 on the inlet side of the sliding surface (opposite to the rotating direction of the rotating shaft 1) is an axial position (in FIG. 2) where the oil supply means 3 is provided. The position in the circumferential direction is retreated in the rotational direction of the rotary shaft 1 toward the axial end portions (B and B ′ in FIG. 2) of the pad. In the present embodiment, each pad 2 is formed with an inlet groove 6 by, for example, cutting or molding. The inlet groove 6 is provided on the sliding surface 7 of the pad 2 at the end of the rotary shaft 1 on the inlet side.

  Next, the effect of this embodiment is demonstrated using FIG. FIG. 3 is a perspective view illustrating the flow of oil in the first embodiment of the present invention together with the structure of the pad and the oil supply means. As shown in FIG. 3, the lubricating oil supplied from the oil supply means 3 is supplied to the oil film as indicated by X at the same axial position. The lubricating oil that has not fully entered the oil film at the same axial position as the oil supply means 3 flows to the oil film after flowing in the axial direction along the sliding surface leading edge 8, as indicated by Y and Y 'in FIG. Supplied. In the present embodiment, the sliding surface leading edge 8 recedes toward the end in the axial direction, so that an axial flow is generated in the lubricating oil flowing along with the rotating shaft 1, so that Y or Y ′ Become a flow. Thereby, the low-temperature lubricating oil supplied from the oil supply means 3 can be introduced into the oil film in a wide range in the axial direction without flowing out to the outside, and the sliding surface temperature can be reduced.

  As a method of supplying low temperature oil supply in a wide range in the axial direction, a method of providing a plurality of oil supply means 3 in the axial direction is also conceivable, but in this case, the speed of the lubricating oil flowing out from the oil supply means becomes slow. . By the way, the higher the outflow speed of the lubricating oil from the oil supply means, the higher the temperature of the lubricating oil that flows out from the upstream pad (for example, the pad 2a with respect to the pad 2b) and outflows into the oil film while adhering to the surface of the rotating shaft 1 (hot Considering that it is possible to eliminate (referred to as oil carry-over), it is preferable that the number of oil supply means 3 is small. Further, since the pressure of the oil film becomes high at the center in the axial direction, it is effective to reduce the temperature of the oil film at the center in the axial direction in order to avoid damage. Therefore, the configuration as in the present embodiment has a greater effect of improving the reliability of the bearing than providing a plurality of oil supply means in the axial direction. Even when a plurality of oil supply means are provided in the axial direction, the other oil supply means may be auxiliary compared to the oil supply means in the center in the axial direction.

(Second Embodiment)
A second embodiment of the present invention will be described with reference to FIG. Note that in this embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

  FIG. 4 is a perspective view showing the structure of the pad 2 in the present embodiment together with the oil supply means 3.

  Also in this embodiment, as in the first embodiment, the low-temperature lubricating oil supplied from the oil supply means 3 can be introduced into an oil film in a wide range in the axial direction without flowing out to the outside. It is possible to reduce the surface temperature. In the present embodiment, the open groove 6 is also provided on the upstream side of the sliding surface front edge 8 of the pad 2 (on the side opposite to the rotation direction of the rotary shaft 1). By configuring in this way, the lubricating oil supplied from the oil supply means is collected in the inlet groove and then guided to the oil film, which can further reduce the amount of lubricating oil flowing out of the oil film. It becomes possible.

(Third embodiment)
A third embodiment of the present invention will be described with reference to FIG. In the present embodiment, the same parts as those in the second embodiment are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

  FIG. 5 is a perspective view showing the structure of the pad 2 in the present embodiment together with the oil supply means 3.

  In the present embodiment, the most upstream portion of the sliding surface leading edge 8 is partially linear in the axial direction. Moreover, the depth of the inlet groove 6 becomes shallow as it goes downstream.

  Also in this embodiment, as in the first embodiment, the low-temperature lubricating oil supplied from the oil supply means 3 can be introduced into an oil film in a wide range in the axial direction without flowing out to the outside. The sliding surface temperature can be reduced. In the present embodiment, the most upstream portion of the sliding surface leading edge 8 is partially linear in the axial direction. As a result, the lubricating oil supplied from the oil supply means 3 is less likely to be induced in the axial direction at the linear position, so that it is surely introduced into the downstream oil film. Moreover, in this embodiment, the depth of the entrance groove | channel 6 becomes shallow as it goes downstream. With this configuration, the lubricating oil easily flows into the oil film from the inlet groove, so that the lubricating oil supplied from the oil supply means 3 can be efficiently introduced into the oil film.

DESCRIPTION OF SYMBOLS 1 Rotating shaft 2, 2a-2e Pad 3, 3a-3e Oil supply means 4 Pivot 5 Housing 6 Entrance groove 7 Sliding surface 8 Sliding surface leading edge

Claims (6)

A plurality of pads disposed on the outer peripheral side of the rotating shaft and provided so as to be swingable;
In a tilting pad journal bearing provided between the plurality of pads and provided with a plurality of oil supply means for directly supplying oil between the outer peripheral surface of the rotating shaft and the inner peripheral surface of the pad,
A tilting pad journal bearing characterized in that a circumferential position of the leading edge of the sliding surface of the pad has a portion that recedes from the axial center toward the axial end.   2. The tilting pad journal bearing according to claim 1, wherein an inlet groove is provided on an upstream side of a leading edge of the sliding surface of the pad, and the inlet groove is opened upstream and axially.   3. The tilting pad journal bearing according to claim 2, wherein the inlet groove is also provided on the upstream side of the most upstream portion of the leading edge of the sliding surface of the pad. 4. The tilting pad journal bearing according to claim 1, wherein the most upstream portion of the leading edge of the sliding surface of the pad is partially linear in the axial direction. 5. 5. The tilting pad journal bearing according to claim 2, wherein a depth of the inlet groove becomes shallower toward a downstream side. 6. The tilting pad journal bearing according to claim 1, wherein the oil supply means is disposed only at the same axial position as the most upstream portion of the sliding surface.

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