JP5067391B2 - Centrifugal compressor and rotating machine - Google Patents

Description

  The present invention relates to a centrifugal compressor and a rotary machine using a tilting pad type for a journal bearing.

  A tilting pad type bearing shown in Non-Patent Document 1 is used as a bearing of a rotating machine that operates at a high speed. This bearing is said to be less susceptible to vibrations such as oil whip and oil whirl that occur during high-speed rotation exceeding the critical speed.

  In such a tilting pad type bearing, the temperature of the lubricating oil flowing into the sliding surface at the front edge in the pad circumferential direction increases as the rotational speed increases. This is because high-temperature lubricating oil flowing out from the trailing edge of the sliding surface of one pad flows into the leading edge of the sliding surface of the next pad, and is called hot oil carryover. As described above, when the temperature at the leading edge of the sliding surface of the pad is increased, the maximum temperature of the lubricating oil on the sliding surface is also increased, and there is a problem that the bearing is easily burned out and the reliability is lowered.

  As a method for solving such a problem, Japanese Patent Application Laid-Open No. 2008-151239 discloses a configuration including a bypass channel that guides high-temperature oil in an oil film to the outside of the sliding surface.

JP 2008-151239 A

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

  However, even if the bypass passage is provided, the effect of eliminating the influence of hot oil carryover is small. This is because the amount of lubricating oil discharged to the outside of the sliding surface through the bypass passage is not so much as compared with the amount of lubricating oil flowing through the oil film. Most of the lubricating oil flowing through the oil film flows to the next pad as it is. For this reason, the inlet temperature of the next pad hardly changes depending on whether or not there is a bypass flow path.

  This invention is made | formed in view of the said subject, and aims at providing the centrifugal compressor which excluded the influence of hot oil carryover.

  To achieve the above object, a rotating shaft, a bearing that supports the rotating shaft, an impeller attached to the rotating shaft, a suction port for sucking gas by rotation of the rotating shaft, and rotation of the rotating shaft A centrifugal compressor having a discharge port for discharging the gas compressed by the step, wherein the bearing comprises a plurality of pads, and at least one of the plurality of pads is in contact with the rotating shaft. A first opening provided on a surface to be provided, a second opening provided on a surface different from the surface provided with the first opening, the first opening, and the second opening An oil passage hole communicating with the opening is provided, and a cross-sectional area of the oil passage hole increases from the first opening toward the second opening.

  Further, the different surface is a side surface of the pad.

  Furthermore, the angle formed by the front end portion of the oil passage hole and the rear end portion of the oil passage hole is 30 ° to 45 °.

  Further, the first edge formed by the front end portion of the oil passage hole and the second opening portion is more than the second edge formed by the rear end portion of the oil passage hole and the second opening portion. It is provided on the opposite side of the rotation direction of the rotation shaft.

  Furthermore, it is characterized by having an oil filler opening provided in the vicinity of the first and second edges.

  A rotating shaft; a bearing supporting the rotating shaft; an impeller attached to the rotating shaft; a suction port for sucking gas by rotation of the rotating shaft; and the gas compressed by rotation of the rotating shaft. And the bearing comprises a plurality of pads, and at least one of the plurality of pads is provided on a surface in contact with the rotating shaft. The first opening, the second opening provided on a surface different from the surface provided with the first opening, and the first opening and the second opening communicate with each other. The oil passage hole is provided at a location located in a direction opposite to the rotation direction of the rotation shaft from at least one pad that receives a load from the rotation shaft, and the cross-sectional area of the oil passage hole is the first through hole. Increase from the opening to the second opening And features.

  According to the present invention, it is possible to provide a centrifugal compressor that eliminates the influence of hot oil carryover.

2 is a cross-sectional view of the pad of Example 1. FIG. 1 is a perspective view of a pad according to Embodiment 1. FIG. 6 is a perspective view of another example of the pad of Example 1. FIG. FIG. 6 is a perspective view of still another example of the pad of Example 1. It is a figure which shows the oil film temperature of the conventional bearing and the bearing of Example 1. It is a figure which shows the comparison of the flow in an oil passage hole with the case where (theta) is 0 and a certain angle. It is a graph which shows the relationship of angle (theta) which the front end side wall surface and rear end side wall surface of an oil passage hole make, and C point oil film temperature. FIG. 3 is a cross-sectional view showing an example of the pad arrangement of Example 1. 6 is a cross-sectional view showing another example of the pad arrangement in Example 1. FIG. 6 is a cross-sectional view of Example 2. FIG. It is a perspective view of the pad of Example 2. 6 is a cross-sectional view of a centrifugal compressor of Example 3. FIG. It is a graph which shows the comparison with the former about the rotation speed and discharge pressure of the centrifugal compressor of Example 3.

  Example 1 will be described with reference to FIGS.

  1 is a cross-sectional view of a tilting pad type bearing of Example 1. FIG. FIG. 2 is a perspective view of the pad of FIG. FIG. 3 is a perspective view of another example of the pad of FIG. FIG. 4 is a perspective view of still another example of the pad of FIG. FIG. 5 is a graph showing the oil film temperature of the conventional bearing and the bearing of Example 1. FIG. 6 is a diagram showing a comparison between the case where θ is 0 and the case where there is a certain angle. FIG. 7 is a graph showing the relationship between the angle θ formed by the side wall of the front end portion 14 of the oil passage hole 13 and the side wall of the rear end portion 15 of the oil passage hole 13 and the point C oil film temperature. Here, the front end portion 14 of the oil passage hole 13 is a portion provided in the side opening 12 in a direction from the side closest to the housing 2 toward the rotary shaft 1. The rear end portion 15 of the oil passage hole 13 is a portion provided in the side opening 12 in a direction from the side closest to the rotation shaft 1 toward the rotation shaft 1.

  FIG. 8 is a cross-sectional view illustrating a pad arrangement example according to the first embodiment. FIG. 9 is a cross-sectional view illustrating another pad arrangement example of the first embodiment.

  The tilting pad type bearing pad 3 of Example 1 will be described with reference to FIG. A sliding surface opening (first opening) 11 is provided in the vicinity of the circumferential rear end of the sliding surface between the pad 3 and the rotating shaft 1, and the sliding surface opening 11 is provided on the side surface of the pad. An oil passage hole 13 that communicates with the side opening (second opening) 12 is provided. The cross-sectional area of the oil passage hole 13 increases from the sliding surface opening 11 toward the side opening 12.

  FIG. 2 shows a perspective view of the pad 3 of FIG. One sliding surface opening 11, one side opening 12, and one oil passage hole 13 are provided.

  FIG. 3 shows a perspective view of another example of the pad of FIG. The sliding surface openings 11, 11 ', 11 ", the side openings 12, 12', 12" and the oil passage holes 13, 13 ', 13 "are provided in three each and are arranged in the bearing width direction. In this way, the sliding surface openings 11 may be provided at a plurality of locations.

  FIG. 4 shows a perspective view of another example of the pad of FIG. The width of the side opening 12 is wider than the width of the sliding surface opening 11. Thus, the width of the side surface opening 12 and the sliding surface opening 11 does not necessarily have the same area.

  Next, operations and effects of the first embodiment will be described.

Along with the rotation of the rotating shaft, lubricating oil flows into the sliding surface of the pad 3 to form an oil film. The temperature of the oil film gradually increases as it proceeds to the circumferential rear edge of the pad. In the case of a conventional pad, the temperature of the oil film has a distribution indicated by a dotted line in FIG. Note that A, B, C, and D on the horizontal axis in FIG. 5 indicate the positions of the respective points shown in FIG. 1, and in the conventional pad, point B is the rear end of the pad. The oil supply temperature T ₀ from the external oil supply device at this time is shown in FIG. The temperature at the circumferential front edge (point A) of the oil film is higher for the conventional pad. This is because the lubricating oil flowing into the oil film at the leading edge is mixed with the lubricating oil having a substantially oil supply temperature filled in the bearing housing and the high-temperature lubricating oil flowing out from the oil film on the pad on the leading edge side.

  In the pad according to the first embodiment, the oil film temperature is lowered by being mixed with the low-temperature lubricating oil around the pad at the sliding surface opening 11 between the points B and C. Distribution. Between point C and point D, the temperature rises again slightly because the oil film becomes thinner. However, since a part of the oil film is scraped off at the point C, the temperature at the point B is not reached. After passing through the point D, the oil film temperature decreases again.

  The flow of the lubricating oil in the sliding surface opening 11 between the points B and C will be described with reference to FIG. FIG. 6A shows a case where the angle θ formed by the front end surface 14 and the rear end surface 15 of the oil passage hole 13 is 0 °. FIG. 6B shows the flow in the oil passage hole 13 when θ has an angle. As shown in FIG. 6A, when θ is 0 °, only a flow that flows out from the sliding surface to the side surface occurs. Moreover, since this flow rate is not large, the effect of reducing the oil film temperature is small. On the other hand, as shown in FIG. 6B, when θ is larger than 0 °, a flow that flows from the side surface side to the sliding surface side also occurs, so the oil film temperature is increased at the sliding surface opening 11. Can be reduced.

  As shown in FIG. 7, the effect of temperature reduction at the sliding surface opening 11 varies depending on the angle of θ. When θ is about 30 °, a sufficient effect can be obtained. Even when 45 ° or more, the larger θ is more effective, but the change gradually decreases. Therefore, it is better to set θ to 30 ° to 45 °.

  In addition, providing the structure of Example 1 on the pad 3 induces a flow swirling in the oil passage hole 13 as described above, and thus there is a concern of increasing the loss of the lubricating oil. In order to avoid this, it is only necessary to apply the structure of the first embodiment to only a part of the pads instead of all the pads of the bearing. An example using this structure will be described in detail with reference to FIGS.

  FIG. 8 is a view showing a load bite pad type bearing. In the load bite pad type, no pad is provided in the load direction of FIG. 8, and as shown in FIG. 8, the load from the rotating shaft 1 is mainly two pads (one 103 and one 203). It is a method concerning. In FIG. 8, the pad 203 having the structure of the first embodiment is provided at a position located in the direction opposite to the rotation direction of the rotary shaft 1 from the load direction.

  FIG. 9 is a view showing a load-on-pad type bearing. In the load-on-pad type, pads are provided in the load direction of FIG. 9, and as shown in FIG. 9, the load from the rotating shaft 1 is mainly three pads (two 103 and one 203). It is a method concerning. In FIG. 9, the pad 203 having the structure of the first embodiment is provided at a position located in the direction opposite to the rotation direction of the rotary shaft 1 from the pad 103 that mainly receives a load from the load direction.

  That is, in FIGS. 8 and 9, the pad having the above-described structure is provided at a position located in a direction opposite to the rotation direction of the rotary shaft 1 from at least one pad that receives a load from the rotary shaft 1.

  Next, Example 2 will be described with reference to FIGS.

  FIG. 10 is an external view of the pad 3 of the tilting pad type bearing of the second embodiment. FIG. 11 is a perspective view of the pad 3 according to the second embodiment.

  In the second embodiment, as shown in FIGS. 10 and 11, the first edge 16 between the wall surface of the front end surface 14 of the oil passage hole 13 and the side opening 12 is the wall surface of the rear end surface 15 of the oil passage hole 13. And the second edge 17 between the side opening 12 and the side opening 12 on the opposite side of the rotation direction of the rotary shaft 1. That is, the straight line drawn from the first edge 16 toward the center of the rotary shaft 1 is different from the straight line drawn from the second edge 17 toward the center of the rotary shaft 1. In addition, the shape of the pad 3 is a shape that is recessed in the direction opposite to the rotation direction of the rotary shaft 1 as it goes from the second edge 17 to the first edge 16. With this structure, the lubricating oil around the pad 3 can easily flow into the oil passage hole 13.

  Further, as shown in FIG. 10, an oil supply hole 22 is provided in the vicinity of the side opening 12. With this structure, the lubricating oil having a lower temperature flows into the oil passage hole 13, so that the effect of reducing the temperature at the sliding surface opening portion 11 becomes greater.

Needless to say, the pads of the structure of the second embodiment are not used for all the pads of the bearing as in the first embodiment, and the structure of the second embodiment may be applied to only a part of the pads.
Needless to say, the application method may be the same as in the first embodiment.

  Next, Example 3 will be described with reference to FIGS.

  FIG. 12 is a cross-sectional view of a centrifugal compressor. FIG. 13 is a graph showing a comparison of the operation rotational speed and discharge pressure of the centrifugal compressor according to Example 3 with the conventional one.

  In Example 3, the tilting pad type shown in Example 1 or 2 is used for the journal bearing (bearing) of the centrifugal compressor.

First, the centrifugal compressor will be described with reference to FIG. A casing 301 accommodates a rotating shaft 303 supported by journal bearings 304a and 304b.
The impeller 302 attached to the rotation shaft 303 compresses the gas sucked from the suction port 305 by the rotation of the rotation shaft 303 and discharges it from the discharge port 306.

  As shown in FIG. 13, by using the tilting pad type of Example 1 or 2 for the rotating machine, the temperature of the oil film is reduced and the number of revolutions reaching the critical oil film temperature is increased. N1 is increased from N1 to N2, and the operating range of the rotating machine can be expanded. In particular, by using the tilting pad type of Example 1 or 2 as the journal bearing of the centrifugal compressor, the discharge pressure of the centrifugal compressor can be increased from P1 to P2. Therefore, a higher-pressure centrifugal compressor can be realized without changing the size of the tilting pad type pad.

  As described above, according to the first to third embodiments, at the trailing edge of the sliding surface of the pad, it is possible to reduce the temperature by mixing the high temperature lubricating oil that has passed through the sliding surface with the low temperature lubricating oil on the side surface of the pad. Become. Furthermore, by discharging a part of the lubricating oil out of the sliding surface, the temperature of the lubricating oil at the leading edge of the next pad can be lowered, so it is possible to provide a highly reliable centrifugal compressor It becomes.

1,303 Rotating shaft 2 Housing 3, 3 ', 203 Pad 4 Pivot 5,305 Suction port 11, 11', 11 "Sliding surface opening (first opening)
12, 12 ', 12 "side opening (second opening)
13, 13 ', 13 "Oil passage hole 14 Front end surface 15 Rear end surface 16 Edge (first edge) of wall surface of front end surface 14 of oil passage hole 13 and side surface opening 12
17 Edge (second edge) between the wall surface of the rear end face 15 of the oil passage hole 13 and the side opening 12
22 Oil supply hole 103 Normal pad 301 Casing 302 Impeller 304 Journal bearing 306 Discharge port

Claims (7)

A rotary shaft, a bearing that supports the rotary shaft, an impeller attached to the rotary shaft, a suction port for sucking gas by rotation of the rotary shaft, and discharging the gas compressed by rotation of the rotary shaft A centrifugal compressor provided with a discharge port,
The bearing comprises a plurality of pads,
At least one of the plurality of pads is
A first opening provided on a surface in contact with the rotating shaft;
A second opening provided on a surface different from the surface provided with the first opening;
An oil passage hole is provided for communicating the first opening and the second opening;
The centrifugal compressor according to claim 1, wherein a cross-sectional area of the oil passage hole increases from the first opening toward the second opening. The centrifugal compressor according to claim 1,
The centrifugal compressor according to claim 1, wherein the different surface is a side surface of the pad. The centrifugal compressor according to claim 1,
The angle formed by the front end portion of the oil passage hole and the rear end portion of the oil passage hole is any one of 30 ° to 45 °. The centrifugal compressor according to claim 1,
The first edge formed by the front end portion of the oil passage hole and the second opening portion is more rotatable than the second edge formed by the rear end portion of the oil passage hole and the second opening portion. A centrifugal compressor characterized in that it is provided on the opposite side of the rotation direction. The centrifugal compressor according to claim 4,
A centrifugal compressor comprising an oil filler port provided in the vicinity of the first and second edges. A rotary shaft, a bearing that supports the rotary shaft, an impeller attached to the rotary shaft, a suction port for sucking gas by rotation of the rotary shaft, and discharging the gas compressed by rotation of the rotary shaft A centrifugal compressor provided with a discharge port,
The bearing comprises a plurality of pads,
At least one of the plurality of pads is
A first opening provided on a surface in contact with the rotating shaft;
A second opening provided on a surface different from the surface provided with the first opening;
An oil passage hole communicating the first opening and the second opening;
From at least one pad that receives a load from the rotating shaft, provided in a location that is opposite to the rotating direction of the rotating shaft,
The centrifugal compressor according to claim 1, wherein a cross-sectional area of the oil passage hole increases from the first opening toward the second opening. A rotary machine comprising a rotary shaft and a bearing that supports the rotary shaft,
The bearing comprises a plurality of pads,
At least one of the plurality of pads is
A first opening provided on a surface in contact with the rotating shaft;
A second opening provided on a surface different from the surface provided with the first opening;
An oil passage hole is provided for communicating the first opening and the second opening;
The rotary machine according to claim 1, wherein a cross-sectional area of the oil passage hole increases from the first opening toward the second opening.

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