JPS5850312A - Journal bearing - Google Patents

Abstract

PURPOSE:To improve oil film pressure borne by a segment and largely prolong the life of a bearing by setting a place for installing a segment positioned at the lowermost part within a definite range. CONSTITUTION:When an interval between a rotary shaft 1 in a stationary state and segment 2 positioned at the lowermost part and also an interval between said rotary shaft 1 not in rotary motion and other segment 3, 7 adjacent to the segment 2 positioned at the lowermost part are defined as L1 and L2 respectively, the segment 2 positioned at the lowermost part is so installed as to satisfy the relation 2>=L1/L2>=1.25 between the intervals L1 and L2. Thus, oil film pressure P2 borne by a segment 2a is about same as oil film pressure P3, P7 borne by other adjacent sections 3a, 7a respectively. The oil film pressures borne by those segments are not only equalized but also reduced in its peak value in comparison with that of the conventional structure. As a result, the total bearing capacity is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a bearing for, for example, a high-speed rotating machine, and particularly to a journal bearing.

Conventionally, journal bearings have been used as a structure to support high-speed, high-load rotating shafts, and the pressure generated in the oil film of the journal bearing under static load is calculated using the following Reynolds equation 1'- has been done.

However, x = rθ, pr is the radius of the shaft, θ is the bearing angle, 2
is the coordinate in the width direction, and p is the oil film pressure. In addition, h is the oil film shape, C is the radial clearance, ε is the eccentricity, e is the amount of eccentricity, η is the viscosity of the lubricating oil, and U is the circumferential speed of the shaft, and between these (= h = c (1 + ε cos θ) , ε==e/c.

Initially, the above Reynolds equation can be applied to journal bearings with continuous walls, but in journal bearings with multiple sections, the oil film shape and oil film pressure become complicated depending on the shape, arrangement, and number of sections. Furthermore, it is difficult to calculate the oil film pressure distribution based on calculations when considering the positional fluctuations associated with the operation of the rotating shaft (2), and in general, experimental values (
- Therefore, it is calculated.

FIG. 1 shows the positional relationship between the rotating shaft and the intercept in an embodiment of a conventional journal bearing, and FIG. 2 shows actual measurements of the distribution of oil film pressure when the journal bearing shown in FIG. 1 is operated. That is, in FIG. 1, 1 is a rotating shaft, and 2 to 7 are sections that support the rotating shaft 1.The sections 2 to 7 are attached to the outer cover 20 by supports 12 to I7, respectively. When the rotation 11111 is stationary (the second is the rotation axis l
The center point Q of coincides with the center of the pitch circle of intercepts 2 to 7, but when the rotating shaft 1 is rotating at high speed, the center of the rotating shaft 1 moves from the center point Q to the center point Q'T-, The rotating shaft 1 moves to the position of the rotating shaft 1a indicated by the dotted line. Also, rotating shaft 1
When a is rotating at high speed, the sections 2 to 7 are also displaced about the supports 12 to 17 due to the influence of oil film pressure, and are in the state of sections 2a to 7a shown by dotted lines. According to actual measurements (2), in journal bearings that use sections divided into multiple pieces, the rotating shaft moves vertically as the rotating shaft rotates at high speed, so the distance between the circumference of the rotating shaft and the sections is The distance is minimum at the lowest segment 2a, and the distance between the two changes from 14 km apart when the rotating shaft is stopped to 1 m when rotating at high speed.

Next (1 Figure 1 (2) The distribution of oil film pressure P shown in Figure 2 (- is shown. (1st place it
It can be seen that the oil film pressure P2 borne by the segment 2a is extremely large compared to the oil film pressure P, , P, borne by each of the other segments 3a and 7a adjacent to the segment 2ai.

However, the performance of journal bearings under two-fluid lubrication is affected by the maximum pressure in the oil film, the maximum oil film temperature, and the minimum oil film thickness, and if these factors are not properly controlled, bearing seizure, vibration, Accidents such as corrosion may occur.In this regard, in the conventional example, an excessive oil film pressure P at the bottom (2nd position) was applied, which significantly shortened the life of the journal bearing. .

The present invention was made in view of the above (1), and by adjusting the position of the segments, the oil film pressure shared by the segments is averaged, thereby providing a long-life journal bearing with less sintering, vibration, and corrosion. is intended to do.

The present invention is based on a journal bearing in which a rotating shaft is supported by a plurality of sections (-), and it is noted that the maximum oil film pressure is applied to the section located at the bottom, and furthermore, the rotation of the section located at the bottom is I11] (While changing the distance between the two, find the ratio of the oil film pressure applied to the intercept located at the bottom and this (== the oil film pressure applied to the adjacent section, and as a result, the ratio between the intercept located at the lowest and the axis of rotation when not rotating) When the distance between the lowest section (=located section (2) and the rotation axis when not rotating is defined as "distance"), the distance between L, (22
It has been found that it is preferable to set the lowermost segment so that the relationship ≧Ll/L2≧125 holds true. As shown in Fig. 3, the oil film pressure ratio Px/Ps shared by these intercepts within the above range is proportional (1
However, when it exceeds this range (2), the oil film pressure ratio changes rapidly (1), which can be understood.

The present invention configures the segments of the journal bearing in an optimal state based on the above-mentioned natural phenomena and determines the mounting position of each segment. The oil film pressure applied by the segment is significantly improved compared to the conventional configuration, and this has the effect of greatly extending the life of the journal bearing.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. Third
In the figure, 1 is a rotating shaft, and 2 to 7 are sections that support the rotating shaft 1. Sections 2-7 are supports 12-1, respectively.
7 is attached to the outside [20], and when the rotating shaft l is stationary, the distance between the rotating shaft 1 and the intercept 2 is LI, and the distance between the rotating shaft 1 and the other intercepts 3 to 7 is L2 Then, the intercepts are arranged so that the relationship 2≧LI/L2≧125 is satisfied between the distances, ,L. In this case, the center point Q of the rotating shaft 1 coincides with the center of the pitch circle of the segments 3 to 7 excluding the segment 2. However, when the rotating shaft 1 is rotating at high speed, the center of the rotating shaft 1 moves from the center point Q to the center point Q', and the rotating shaft 1 moves to the position (2) of the rotating shaft 1a shown by the dotted line. When 1a is rotating at high speed, the sections 2 to 7 also move to the supports 12 to 17 due to the influence of oil film pressure.
is displaced using the fulcrum as a fulcrum, and the state of the sections 2a to 7a shown by the dotted lines is reached.

As described above, the present invention has the following effects (--the distance between the lowermost section and the other adjacent sections to the rotational axis) as shown in FIG. When the distribution of the oil film pressure P is actually measured using the angle θ with respect to the perpendicular passing through the center point Q' as a variable, the results shown in FIG. 5 can be confirmed.

As shown in FIG. 5, the oil film pressure P, which is borne by the segment 2a located at the lowest position, is the same as that of the other segment 3a+ adjacent to the segment 2a.
The oil film pressure P8 borne by each of 7a. P7 is not averaged equally, and its peak value is also about 05 to 07 times smaller than that of the conventional structure. As a result, the total load capacity can be increased by 2 to 15 times. Alternatively, if the load is the same, it is possible to obtain a long-life journal bearing with fewer accidents in terms of overheating, vibration, and corrosion.

According to the embodiment of the present invention (-), in addition to the above-mentioned effects ('''-), there are also the following effects. In FIG. 6, B is the temperature characteristic of the section shown in the conventional example, and A is the present Embodiment of the invention (= Temperature characteristics of the shown intercept. As is clear from FIG. 6, the maximum value of temperature characteristic A is lower than the maximum value of temperature characteristic B, and the journal bearing is operated at a low temperature. In addition to the above effects, it also has a favorable effect on fluid lubricants, making it possible to provide highly reliable journal bearings.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram of a conventional journal bearing, and Figure 2 is an illustration of a conventional journal bearing.
Figure 3 is a curve diagram of the oil film pressure ratio in the journal bearing of the present invention, is4
The figure is an explanatory diagram of a journal bearing showing an embodiment of the present invention.
Fig. 5 is a curve diagram of the oil film pressure in the bearing (2) in Fig. 4, and Fig. 6 is an explanatory diagram of temperature characteristics. 1...Rotating shaft 2-7...Intercept 12-17
...Support (7317) Agent Patent Attorney Noriyuki Chika (
1 other person) C Figure 3 Figure 5 Figure 6 Ryokei

Claims (1)

[Claims] In a journal bearing in which a rotating shaft is supported by a plurality of segments, the distance between the segment located at the lowest position (-) and the rotating shaft when not rotating is Ll, and the distance between the segment located at the lowest position (-) and the rotating shaft when not rotating is When the distance between the intercept of
A journal bearing characterized in that the cut at the lowest position is installed so that the following relationship is established.