JPH0663938B2 - Misalignment status diagnosis method - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] Belonging to the category of state standard maintenance technology.

It belongs to the technical field of configuring an automatic diagnostic method for a machine supported by an oil film bearing in a machine such as a turbine that rotates at a relatively high speed, which requires constant balancing around a rotation axis.

[Prior art]

As a general diagnostic technique, the misalignment state of the rotating body is diagnosed in detail only when there is a possibility that misalignment has occurred when there is a vibration component of 2 or 3 times the rotation frequency in the axial direction. There was no suggestion of how to do it.

[Problems to be Solved by the Invention]

We propose a method for diagnosing the misalignment state of the rotating body in detail from the state of the force supported by the oil film bearing.

[Means for Solving the Problems]

Generally, when an important machine is supported by an oil film bearing, a gap meter for measuring the clearance between the journal and the bearing is provided for each bearing in order to monitor that the minimum oil film thickness is a predetermined value or more.
They are attached individually. The present invention was obtained from the capacity coefficient determined from the bearing form when the position of the journal axis calculated from the output of the gap meter is the highest position in the vertical direction, the lowest position, and the maximum position on both sides in the horizontal direction. The misalignment state of the rotating body is easily diagnosed by using the balance relationship between the bearing supporting force and the force applied to the journal.

The present invention will be described in detail below based on the embodiment shown in FIG. In FIG. 1, a turbine 1 has a generator 2 and respective shafts 3 and 4 which are rigidly connected by a coupling 5. Turbine 1 and generator 2
Is supported on both sides by bearings. Two gap gauges 6-a-1, 6-a-2, 6-b-1, provided for each bearing,
Based on the outputs of 6-b-2, 6-c-1, 6-c-2, 6-d-1, 6-d-2, in the eccentricity calculation unit 7, the downward direction is positive and the lowest in the vertical direction. Eccentricity εd at the highest position, eccentricity ε at the highest position
iu, eccentricity εir, εil at maximum on both sides in the horizontal direction
(However, i = a, b, c, d) is calculated, and the magnitude and direction of the force generated due to the misalignment state in the misalignment state diagnosis unit 8 are obtained according to the method described below. Display by means not shown.
Make a record. The eccentricity here means the distance between the center of each bearing and the journal axis from the output of each gap meter 6-i-1, 6-i-2 (where i = a, b, c, d). Is calculated by dividing by the radial clearance ci of each bearing.

Obviously, in the rotating body, the force to be supported by each bearing changes in the presence of misalignment. According to the inventor's trial calculation, it has been found that the change of each bearing force is determined by the magnitude and direction of the degree of misalignment, regardless of the rotational movement of the journal shaft, in an ordinary industrial level oil film bearing. In each bearing, as shown in Fig. 2, with the center C _B of the bearing as the origin, the X axis in the horizontal direction and the Y axis in the vertical direction are taken, and the highest point of the locus of the journal axis is taken.
U, the Y component of the force applied at the lowest point D The X component of the force applied at the rightmost bearing point R and the leftmost bearing point L Then, it is obvious that there is the following relationship between the force fiu due to unbalance, the force fi _M due to the weight of the rotating body, and the force fi _A due to misalignment.

(However, i = a, b, c, d and below are the same) However, β = direction of force due to misalignment.

Therefore, from equation (1) + equation (2), From equation (3) + equation (4), From equations (5) and (6) If fi _A ≠ 0 Therefore, If (j = u, d, r, l, k = x, y) is known, the magnitude of the force due to the misalignment and its direction β can be known. Therefore, j point (where j = u, d,
If the coordinates of i, l and below) are (xij, yij), the eccentricity εij Therefore, the bearing supporting force Rij at each j point can be obtained as follows via the capacity coefficient CNij which is a function of the eccentricity εij.

Rij = CNij ・ Sgn (εij) ・ Li ・ Di ・ (Di / 2ci) ²・ μ
・ N …… (7) where Sgn (z) = sign of z L = effective bearing length D = journal diameter c = radial clearance μ = lubricant viscosity coefficient N = revolutions per second However, A = 2.2-0.5 ・ (L / D) B = -1.4 + 0.5 ・ (L / D) C = Depends on the bearing type.

For example, when 5 tilting bad, LOP The third example of capacity coefficient CN is shown in the case of L / D = 0.7.
Shown in the figure. The solid curve is the value calculated by the equation (8), and the white circles are the reference values based on the data described in “Data Collection of Static and Dynamic Characteristics of Sliding Bearings” edited by the Japan Society of Mechanical Engineers, page 278. In addition, the relational expression shown by the equation (8) can be obtained from literature, for example, RRSL.
AYMAKER BEARING LUBLICATION ANALYSYS P31 TABLE3.
1, Mechanical Engineering Handbook B-1-37, Figure 150, edited by the Japan Society of Mechanical Engineers, "Static and dynamic characteristics data collection of slide bearings", pages 186, 278 However, even if the various coefficients are corrected based on the actual data on site, it does not depart from the technical idea of the present invention.

When the bearing support force at each point is known Is the expression (9), (10) Therefore, the misalignment state can be diagnosed.

Further, in place of both the highest-lowermost vertical direction and the outermost azimuths of the horizontal direction of the journal shaft center occurring in the bearing, at least one set of relationships that can be placed at a position with a rotation angle difference of 180 ° in the track of the shaft center is used. Use of two sets does not depart from the present technical idea.

The operations described above can be easily performed by using a computer equivalent to a so-called personal computer that is widely used, so that there is no difficulty in implementing the present invention.

〔The invention's effect〕

By slightly improving the existing oil film bearing monitoring system, it becomes possible to easily diagnose the misalignment state of a machine such as a turbine that rotates at a relatively high speed.

[Brief description of drawings]

FIG. 1 is a block diagram showing a device configuration for carrying out the present invention in one mode, FIG. 2 is an explanatory diagram of a coordinate system which is configured with a center of a bearing as an origin, and FIG. It is an illustration figure of a relationship. 1: Turbine, 2: Generator 3,4: Shaft, 5: Coupling 6-a-1, 6-a-2, 6-b-1, 6-b-2, 6-c-1, 6-
c-2, 6-d-1, 6-d-2 ,: Gap meter 7: Eccentricity calculation section 8: Misalignment state diagnosis section

Claims (1)

[Claims] 1. In a rotating body supported by an oil film bearing, the highest vertical position of the journal axis formed in the bearing.
A method for diagnosing a misalignment state, which comprises diagnosing a misalignment state from a relationship between forces at a lowest position and both lateral positions.