JPH08128441A - Bearing metal variable phase-type bearing - Google Patents

Abstract

PURPOSE: To provide a high performance bearing metal variable phase-type bearing for exhibiting oil film properties most suitable for vibrational properties of a rotary shaft, and achieving stability of a shaft system through a process of changing the critical speed and unbalanced response characteristics in relation to the change of the operational condition of the rotary shaft. CONSTITUTION: A bearing metal 03 is inserted into a bearing housing 10 so as to be turned around its axis. In a slide bearing such as a cylindrical bearing, two circular-arc bearing, and a tilting pad bearing provided with a structure for rotating the bearing metal 03 to the optional phase in the circumferential direction, teeth 05 notched on a part of the outer periphery or on the whole periphery of the bearing metal 03 and a phase adjusting means 06 of the bearing metal 03 supported to the bearing housing 10, and on which teeth to be meshed with the teeth 05 of the bearing metal 05 are projectingly provided are provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bearing metal variable phase type bearing.

[0002]

2. Description of the Related Art As shown in FIG. 13, various slide bearings commonly used in rotary machines have an annular clearance 02 in a bearing metal 03 in which a rotary shaft 01 is fitted and fixed in a bearing hole of a bearing housing 10. And the annular clearance 02 is filled with lubricating oil. Since the annular bearing metal 03 is fixed in this type of slide bearing, the oil film coefficient cannot be changed during rotation of the rotary shaft 01.

[0003]

By the way, normally, the vibration characteristics of the rotary shaft system are determined by the specifications of the shaft system and the oil film characteristics of the bearing, as shown in FIG. In a normal rotating machine,
The specifications of the shaft system will be almost determined if the type, output, and performance of the rotating machine are determined. Depending on the type, not only the weight of the rotor in a high-pressure turbine, but also the steam reaction force that cannot be ignored under partial load conditions is In addition, since the compressor receives a tooth reaction force corresponding to the load, the axial load direction may change in some compressors. On the other hand, the oil film characteristics of the bearing vary greatly not only with the type of bearing, but also with the bearing specifications such as bearing width and bearing clearance. However, as described above, in the conventional bearing, the oil film coefficient cannot be changed during the operation of the rotating machine. Bearings must be designed in consideration of such factors. For this reason, in general, not only the quality of the bearing becomes excessive, but also the vibration characteristics may not always be optimally designed depending on the conditions.

The present invention has been proposed in view of such circumstances, and exhibits optimum oil film characteristics for the vibration characteristics of the rotating shaft, and has a critical speed and unbalanced response characteristics with respect to changes in the operating conditions of the rotating shaft. It is an object of the present invention to provide a high-performance bearing metal variable phase type bearing in which the stability of the shaft system is improved by changing the above.

[0005]

To this end, the invention according to claim 1 is characterized in that a bearing metal is inserted into a bearing housing so as to be rotatable about its axis, and the bearing metal is arranged in an arbitrary phase in the circumferential direction. In a sliding bearing such as a perfect circular bearing, a two-circle bearing, a tilting pad bearing, etc. having a rotatable structure, a tooth formed along a part or the whole outer circumference of the bearing metal and a bearing housing thereof. It is characterized by further comprising: a bearing metal phase adjusting means that is axially supported and has teeth that mesh with the teeth of the bearing metal.

According to a second aspect of the present invention, instead of the teeth engraved along a part or the entire circumference of the bearing metal in the first aspect, a part or the entire circumference of one end of the bearing metal is used. It is characterized by having teeth engraved on it.

Further, a third aspect of the present invention is that, in the first or second aspect, an oil supply hole formed in the bearing metal in a radial direction and a squeeze oil film formed between the housing and the bearing metal. It is characterized by having.

According to a fourth aspect of the present invention, a bearing metal is inserted into a bearing housing so as to be rotatable about its axis, and the bearing metal has a structure capable of rotating in any phase in the circumferential direction. In sliding bearings such as circular bearings, two-circle bearings and tilting pad bearings, two types of hydraulic pressure are provided between the bearing metal and the bearing housing, and the volume changes with the phase change of the bearing metal with respect to the bearing housing. The present invention is characterized by including a chamber, a phase detecting means of the same bearing metal for the same bearing housing, and a means for applying appropriate hydraulic pressures to the two types of hydraulic chambers based on signals from the same phase detecting means.

[0009]

According to this structure, the bearing oil film characteristics are changed because the direction of the bearing load acting on the effective load surface of the bearing is relatively changed by moving the bearing metal in the circumferential direction. As a result, as shown in the mechanical equivalent model diagram of FIG. 5, the oil film characteristics (spring and damping coefficient) of the bearing change, so that the critical speed determined by the specifications of the shaft system and the bearing oil film characteristics,
Unbalanced response characteristics and shaft system stability can be changed. As a result, by moving and supporting the bearing metal in a phase in which the optimum bearing performance can be utilized according to the operating conditions of the rotating machine, the performance of the used bearing can be maximized and optimum vibration characteristics can be obtained.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, an embodiment of the present invention will be described with reference to FIGS. 1, 2 and 3, respectively.
Example, a longitudinal sectional view showing the third embodiment and its transverse sectional view,
FIG. 4 is a transverse sectional view showing the fourth embodiment, and FIGS. 5 and 6 are mechanical equivalent model diagrams showing the oil film characteristics of the first and second embodiments shown in FIGS. 1 and 2, respectively. A mechanical model diagram showing the oil film characteristic of the third embodiment shown in FIG. 3, FIG. 7, FIG. 8, FIG. 9, FIG. 10, and FIG. 11 are two circular arc bearings when the present invention is applied to a perfect circular bearing with an oil groove. Applied to the offset bearing, applied to the 4TP bearing, applied to the 5TP bearing, a static and dynamic characteristic contour map, and FIG. 12 shows the vibration characteristics of the shaft system according to each bearing type of FIGS. It is a list figure which shows a comparison.

In the above drawing, the same reference numerals as those in FIG. 13 indicate the same members as those in the same drawing. First, in the first embodiment shown in FIG. 1, a part of the outer circumference of the bearing metal 03 or the entire circumference thereof is shown. The tooth 05 is attached along with the pinion 06, which is driven by the motor 07, meshes with the tooth 05, so that the phase can be adjusted by slightly moving the bearing metal 03 in the circumferential direction even when the rotary shaft 01 is rotating. I am trying. Here, 10 is a housing that rotatably supports the outer periphery of the bearing metal 03.

Next, in the second embodiment shown in FIG. 2, in order to make the bearing metal 03 rotatable, a tooth 08 is attached to one end in the axial direction of the bearing metal 03 partially or along the entire circumference. By engaging the pinion 06 driven by the motor 07 with the tooth 08, the phase of the bearing metal 03 is made variable even during rotation of the rotary shaft 01. Such first and second
According to the embodiment, since the direction of the bearing load acting on the effective load surface of the bearing is relatively changed, the bearing oil film characteristics (spring coefficient and damping coefficient) are changed, whereby the shaft system specifications and the bearing oil film characteristics are changed. The optimum vibration characteristics are exhibited by changing the critical speed, the unbalanced response characteristics, and the shaft system stability determined by.

Further, in the third embodiment shown in FIG. 3, in the second embodiment of FIG. 2, the lubricating oil is supplied from the oil supply hole 06 in the radial direction of the housing 010 which surrounds the bearing metal 03 with the annular clearance 09. Is supplied to generate a squeeze pressure in the annular clearance 09. According to such a structure, as shown in the mechanical equivalent model diagram of FIG. 6, the rotating shaft 01 has innumerable spring coefficients Kxx, Kxy, Ky based on the lubricating oil 02.
x, Kyy and damping coefficients ωCxx, ωCxy, ωCyx,
The bearing metal 03 is supported by ωCyy, and the bearing metal 03 has an infinite spring coefficient Kpx and damping coefficient WCpx based on the squeeze oil pressure of the annular clearance 09.
Supported by. As a result, in the third embodiment, the movable bearing,
By changing the rigidity of the oil film characteristics of the damper structure,
There is no communication Naruko oil film coefficient, essentially Shaft damper a positive impact on the vibration characteristics of - shafting those valence support rigidity Z _E to enhance the contribution to the vibration characteristics in the form of the illustrated oil film characteristics of structure It is possible to optimize the bearing characteristics at a higher level.

Further, in the fourth embodiment shown in FIG.
Formed between a partition weir projecting radially inward of the bearing housing 13 and a partition weir projecting radially outward of the bearing metal 21 in an annular space between the bearing metal 21 and the bearing housing 13. Hydraulic chambers 14 and 15 with a fan-shaped cross section
Is provided and the hydraulic pressure supplied from the hydraulic pressure source 19 is applied to the hydraulic pressure switching circuit 1
The bearing metal 21 is rotated by switching to the pipe 16 or the pipe 17 by 8. Here, the lubricating oil is supplied between the rotary shaft 1 and the bearing metal 21 by means of an oil groove 11 having a fan-shaped cross section provided in the bearing housing 13 and the bearing metal 21.
Through the oil hole 12 provided in the. Also, the bearing metal 21
The phase of the oil is controlled by controlling the hydraulic pressure switching circuit 18 by the signal of the shaft tachometer 20 to control the hydraulic pressure chambers 14 and 15 for the hydraulic oil of the hydraulic power source 20.
This is done by controlling the supply amount to the.

As a result, when the present invention is applied to sliding bearings of various structures as described below, as will be described later,
Excellent static characteristics and dynamic characteristics can be obtained to the extent that they cannot be compared with the conventional plain bearings shown in FIG. 13, respectively.

First, FIG. 7 shows a case where the present invention is applied to a true circular bearing with an oil supply groove. FIG. 7A shows a hydraulic coefficient calculation mesh diagram, FIG. 7B shows a shaft center levitation characteristic diagram, The same figure (C)
Is the contour map of Sommerfeld number, (D) is the contour diagram of natural frequency, (E) is the contour diagram of damping ratio, (F) is the same diagram as (B) and (E). 3] is a contour map of the damping ratio superimposed with FIG. For example, the effect of the third embodiment of the present invention on the stability of the shaft system will be described with reference to FIG. First, in the case where the rotation speed of the shaft is low and there is not sufficient load capacity, the bearing load angle θ _w = 0 ° and normal installation is performed to obtain sufficient load capacity. Here, it is understood that when the rotational speed increases and the shaft center approaches the center of the bearing clearance 02, the unstable region where the damping ratio becomes negative is large at a normal bearing installation angle θ _w = 0 °. On the other hand, when the installation angle of the bearing metal is rotated clockwise by 30 °, the shaft center passes through the region where the stability is improved due to the influence of the oil supply groove, so for θ _w = 0 ° At θ _w = 30 °, the unstable region is very narrow. In this way, it is possible to change the vibration characteristics of the shaft system by changing the bearing installation angle, and it is possible to optimize the vibration characteristics of the shaft system in the operating conditions of rotating machinery, which was not possible with conventional bearings. Becomes

FIG. 8 shows static / dynamic characteristics when the present invention is applied to a two-arc bearing. Here, the basic view of the drawing is the same as in the case of the true circular bearing up to FIG. 11, but FIG. 8 is simpler in each characteristic diagram than the true circular bearing. This is because the refueling is performed from a position where the clearance in the left-right direction is wide, in other words, the position where oil film pressure is hard to occur, and the influence of the refueling groove is small.
The characteristic points of the relationship between the arbitrary equilibrium point and the shaft system vibration characteristics in a two-circle bearing are summarized as follows. (1) In a normal two-circle bearing operating condition (θ _w = 0 °), the damping ratio increases as the shaft speed increases, but the damping ratio increases from the point where the eccentricity ε _b <0.5 is exceeded. When it becomes smaller and ε _b <0.2, the damping ratio becomes negative and becomes unstable. (2) In the two-circle bearing, the equilibrium position of the shaft center is near the bearing clearance region ε _b ≈0.7, and the region with a large damping ratio is divided into the upper half and the lower half. (3) For this reason, when the load θ _w is increased, the movement locus of the shaft center due to the increase of the rotation speed of the shaft gradually shifts to the region where the damping ratio is small, but at 60 ° or more, the stability is improved again. It (4) That is, in the two-arc bearing, the stability greatly changes depending on the bearing load direction and the positional relationship of the lower bearing metal, and therefore there is a possibility that the stability can be improved by utilizing this characteristic.

FIG. 9 shows the case in which the present invention is applied to a two-offset bearing, and FIGS. 9A to 9E show the relationship between the arbitrary balance point of the two-offset bearing and the vibration characteristic of the shaft system. The features are as follows. (1) The damping ratio is positive even in the region of ε _b <0.1 as compared with the perfect circular bearing and the two-circle bearing, and it is understood that the stability is good. (2) A region having a large damping ratio and good stability is divided into upper right and lower left regions and distributed like an eyeball pattern. (3) Therefore, even in the two-offset bearing, similarly to the two-arc bearing, the shaft system stability can be improved by appropriately selecting the bearing load direction and the bearing installation angle.

FIG. 10 shows the case where the present invention is applied to a 4-tilting pad bearing (hereinafter referred to as 4TP bearing), and the characteristics of the shaft system vibration characteristic at an arbitrary equilibrium point are as follows. (1) From FIG. P. When the bearing is in use, L. O. P. (Load on pad) and L.A.
B. P. In (Load between pads), the shaft center linearly floats toward the bearing center, but when the load direction shifts, the floating characteristic shows a curved shape. (2) 4T. P. In the bearing, the contour map of Sommerfeld number changes along with the bearing clearance shape. This is 4T. P. It is shown that the bearing clearance is almost constant regardless of the load direction when the load magnitude is constant. (3) From FIG. P. The natural frequency of the bearing is L. B. P. The change in natural frequency is small with respect to the change in the load direction, but L. O. P. It should be noted that the natural frequency greatly changes in the load direction close to that state. (4) From FIG. 7E, the stability margin is 4T. P. Bearings are L.O.L. B. P. You can quantitatively confirm that it is better to use in.

FIG. 11 shows a case where the present invention is applied to a 5-tilting pad bearing (hereinafter referred to as 5TP bearing), and its features are as follows. (1) 4T. P. L.L. B. P. And L.A. O.
P. The change in the vibration characteristics is small. 5T. P. In the bearing, multiple pads will always share the load,
It is considered that the vibration characteristics change continuously. (2) While the perfect circular bearing, the two circular arc bearings, and the two offset bearings are unstable at the bearing center, 4T. P. 5T including bearing P. The bearing has the largest stability margin at the center of the bearing. (3) Therefore, T. P. Even when a bearing is used, it is possible to increase the stability margin by properly selecting the bearing specifications and reducing the eccentricity. (4) L. O. P. In the vicinity of 0.7 <ε _b <0.85,
Although there is a stable region with a very large damping ratio, attention must be paid to the design aiming at this part because the region is narrow and the variation range of the damping ratio is large.

The characteristics of the above-mentioned five types of bearings are illustrated as follows.
As shown in Fig. 12, the general stability tendency is as in the conventional findings, but it was found that the stability greatly changes with the bearing load angle θ _w and the bearing installation angle, especially for the two-offset bearing. . Also, it has been found that in a perfect circular bearing, the positional relationship between the load direction and the oil supply groove greatly affects stability.

[0022]

According to such an embodiment, the following effects can be obtained. (1) Minimization of resonance ratio of critical speed By utilizing the fact that the oil film characteristics of the bearing differ depending on the equilibrium point of the shaft center, the bearing metal can be moved to the optimum bearing angle that has been analytically obtained in advance. , It is possible to minimize the resonance magnification when passing a critical speed. (2) Optimization of vibration characteristics at rated rotation speed A bearing angle that maximizes the unbalanced response amplitude and shaft system stability at a specific rotation speed such as the rated rotation speed can be set. (3) Optimization of vibration characteristics of shaft system with large changes in operating conditions In a shaft system where vibration characteristics change due to load changes and other external factors, set the bearing angle that provides optimum vibration characteristics for each condition. can do. Above, (1) ~
In (3), in general, the optimum angles of the bearings do not generally match, and in that sense the conventional ones are designed at the expense of some characteristics. It is possible to realize various shaft vibration characteristics.

In short, according to the first aspect of the present invention, the bearing metal is inserted in the bearing housing so as to be rotatable about its axis, and the bearing metal can be rotated in any phase in the circumferential direction. In a plain bearing, a two-circle bearing, a tilting pad bearing, or other plain bearing having a structure, teeth engraved along a part or the whole circumference of the bearing metal and the bearing supported axially by the bearing housing By providing the phase adjustment means of the bearing metal in which the teeth that mesh with the teeth of the bearing metal are provided, the optimum oil film characteristics for the vibration characteristics of the rotating shaft are exhibited, and against the changes in the operating conditions of the rotating shaft. Therefore, the present invention is extremely useful in industry because a high-performance bearing metal variable phase type bearing is obtained which changes the critical speed and unbalance response characteristics to stabilize the shaft system.

According to the invention of claim 2, claim 1
In this case, in place of the teeth engraved along a part or the entire circumference of the bearing metal, the teeth are engraved along a part or the entire circumference of one end of the bearing metal, so that A high-performance bearing metal variable phase type bearing that exhibits optimum oil film characteristics for shaft vibration characteristics and changes the critical speed and unbalance response characteristics in response to changes in the operating conditions of the rotating shaft to stabilize the shaft system. Therefore, the present invention is extremely useful in industry.

Further, according to the invention of claim 3, in claim 1 or 2, the bearing metal is formed between the housing and the bearing metal, which is formed in the bearing metal in the radial direction. By providing the squeeze oil film, the damping effect due to the squeeze pressure of the movable bearing metal appears significantly in addition to the effects according to claims 1 and 2.
It is possible to optimize the bearing characteristics to a higher degree than in.

According to the invention of claim 4, a bearing metal is inserted into the bearing housing so as to be rotatable about its axis, and the bearing metal is rotatable in any phase in the circumferential direction. In a plain bearing, a two-circle bearing, a tilting pad bearing, and other sliding bearings that are provided, the volume changes with the phase change of the bearing metal provided between the bearing metal and the bearing housing.
By providing different types of hydraulic chambers, phase detecting means for the same bearing metal with respect to the same bearing housing, and means for applying appropriate hydraulic pressures to the two types of hydraulic chambers based on signals from the same phase detecting means, Optimum oil film characteristics are exhibited for the vibration characteristics of the rotating shaft depending on the number of rotations of the rotating shaft, and the stability of the shaft system is improved by changing the critical speed and unbalance response characteristics in response to changes in the operating conditions of the rotating shaft. The present invention is extremely useful industrially because a high-performance bearing metal variable phase bearing is obtained.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view and a lateral sectional view showing a first embodiment of the present invention.

FIG. 2 is a longitudinal sectional view and a lateral sectional view showing a second embodiment of the present invention.

FIG. 3 is a vertical sectional view and a lateral sectional view showing a third embodiment of the present invention.

FIG. 4 is a transverse sectional view showing a fourth embodiment of the present invention.

5 is an equivalent mechanical model diagram showing the oil film characteristics of the first and second embodiments shown in FIGS. 1 and 2. FIG.

FIG. 6 is an equivalent mechanical model diagram showing the oil film characteristics of the third embodiment shown in FIG.

FIG. 7 is a contour map of static and dynamic characteristics when the present invention is applied to a perfect circular bearing with an oil groove.

FIG. 8 is a contour map of static and dynamic characteristics when the present invention is applied to a two-arc bearing.

FIG. 9 is a contour map of static and dynamic characteristics when the present invention is applied to a two-offset bearing.

FIG. 10 is a contour map of static and dynamic characteristics when the present invention is applied to a 4 tilting pad bearing.

FIG. 11 is a contour map of static and dynamic characteristics when the present invention is applied to a 5-tilting pad bearing.

FIG. 12 is a diagram showing a comparison of shaft system vibration characteristics according to the bearing types of FIGS. 7 to 11;

FIG. 13 is a longitudinal sectional view and a transverse sectional view showing a conventional plain bearing.

FIG. 14 is a general acceleration response characteristic diagram of a rotating machine.

[Explanation of symbols]

01 Rotating shaft 02 Lubricating oil (annular clearance) 03 Bearing metal 04 Oil supply pocket 05 Teeth 06 Pinion 07 Motor 08 Teeth 09 Annular clearance 10 Housing 11 Oil groove 12 Oil hole 13 Bearing housing 14 Hydraulic chamber 15 Hydraulic chamber 16 Piping 17 Piping 18 Hydraulic Circuit 19 Hydraulic power source 20 Axis tachometer 21 Bearing metal S Sommerfeld number θ _W Load angle ε _b Eccentricity ζ Damping ratio L. O. P. LOP (Load on pad) L.H. B. P. LBP (Load between pad) T.P. P. Tilting pad

Claims (4)

[Claims] 1. A true circular bearing having a structure in which a bearing metal is rotatably inserted around an axis of the bearing housing so that the bearing metal can be rotated in an arbitrary phase in a circumferential direction, two circular arcs. In plain bearings such as bearings and tilting pad bearings, teeth engraved along part or all of the outer circumference of the bearing metal and teeth that are axially supported by the bearing housing and mesh with the teeth of the bearing metal. A bearing metal variable phase type bearing characterized in that the bearing metal phase adjusting means is provided. 2. The bearing metal according to claim 1, wherein the bearing metal is carved along a part or the whole circumference of one end of the bearing metal instead of the teeth carved along the part or the whole circumference of the bearing metal. Bearing metal variable phase type bearing characterized by having teeth. 3. The bearing metal according to claim 1 or 2, further comprising: an oil supply hole formed in the bearing metal in a radial direction, and a squeeze oil film formed between the housing and the bearing metal. Characteristic bearing metal variable phase type bearing. 4. A true circular bearing having a structure in which a bearing metal is rotatably inserted around an axis of the bearing housing so that the bearing metal can be rotated in an arbitrary phase in a circumferential direction, two circular arcs. In sliding bearings such as bearings and tilting pad bearings, two types of hydraulic chambers, which are provided between the bearing metal and the bearing housing and whose volume changes as the phase of the bearing metal with respect to the bearing housing changes, Phase detecting means of the bearing metal for the housing,
A bearing metal variable phase type bearing, comprising: means for applying proper hydraulic pressure to the two types of hydraulic chambers based on a signal from the same phase detecting means.