JPS61280552A - Method for detecting temperature abnormality of bearing - Google Patents

Abstract

PURPOSE:To detect the temp. abnormality of a bearing with good accuracy, by comparing the temp. rising ratio of the bearing and the evaluation temp. rising ratio thereof and judging the temp. abnormality of the bearing when the temp. rising ratio of the bearing became higher than the evaluation temp. rising ratio thereof. CONSTITUTION:In the embodiment of an upright type water wheel dynamo, the temp. of a thrust bearing and that of cooling water are measured by the resistance thermometer provided to an inlet side and the temp. rising ratio D of the bearing is shown by formula I as the function of bearing evaluation temp. thetax, wherein the correction of the temp. of cooling water was added to the temp. of the bearing, on the basis of the measured temp. Then, the temp. thetax is operated according to the formula I to operate the rising ratio D. Further, an actual temp. rising ratio dtheta/dt is operated. Next, the rising ratio D is compared with the rising ratio dtheta/dt and, when dtheta/dt becomes larger than D, an abnormal alarm is emitted. By this method, the detection of the temp. of the bearing can be performed with good accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a method for detecting temperature abnormalities in bearings, and is intended to reliably detect temperature abnormalities in bearings without being affected by external disturbances such as water temperature. This is what I did.

B0 Summary of the Invention The present invention provides a method for detecting temperature abnormalities in a bearing, in which a bearing conversion temperature is determined from the lubricating oil cooling water temperature and the bearing temperature, and the bearing evaluation temperature increase rate determined from the bearing conversion temperature is calculated based on the bearing temperature. This system detects bearing temperature abnormalities by comparing the determined bearing temperature rise rates, and allows bearing temperature abnormalities to be detected over the entire temperature range regardless of changes in lubricating oil cooling water temperature. .

C1 Conventional technology In general, temperature detection devices are attached to the bearings of generators and water turbines at hydropower stations to protect the bearings, and if the temperature of the bearing becomes abnormal, an alarm is issued and the water turbine is stopped. etc., to prevent damage to the equipment.

Conventionally, in detecting and monitoring the bearing temperature using this bearing temperature detection device, the maximum allowable temperature θ= is set as shown in FIG. 4, and the detected bearing temperature θ1 is the maximum allowable temperature θ! An alarm will be issued when the limit is exceeded. However, with this detection method, if the bearing rises abnormally at low temperatures (immediately after startup),
As shown in @oi, the bearing temperature rise takes 1 time from the start of the abnormal rise until the bearing temperature θl reaches the maximum allowable temperature #.
．． The bearing temperature θ-5 starts after the elapse of L/, t1 time.
An abnormal state can be confirmed. Therefore, by the time the alarm is issued, a serious failure such as seizure of the bearing may already occur.

Therefore, in order to eliminate the drawbacks of the above method, attention has been focused on monitoring abnormalities in the process of increasing the temperature of the bearing, and a method has been proposed in which the abnormality is monitored as a function of the bearing temperature, as shown in FIG. According to this method, the abnormality is judged based on the temperature rise rate, so the responsiveness is good.Moreover, since the temperature rise rate is changed as an accurate abnormality judgment value according to changes in the bearing temperature θ,
Appropriate temperature abnormality judgments can be made whether at startup or after long-term operation.

By the way, when the temperature of the lubricating oil cooling water changes depending on the season, this change occurs in the bearing temperature θ as shown in FIG. In other words, there is a difference of Δtc between water temperature B in summer and water temperature A in winter, resulting in a difference of 4ΔtB in bearing saturation temperature, as shown in Fig. 7, which shows bearing temperature -a as a relationship between temperature increase rate and bearing temperature. The rate of increase in bearing temperature varies depending on the cooling water temperature. Here, the bearing saturation temperature difference ΔtB is generally the cooling water temperature difference Δt
Since the annual change in cooling water temperature is approximately 20°C, the bearing temperature change is approximately 10°C. In FIG. 6, the bearing temperature θ for each time when the cooling water temperature is 0 can be expressed by the following equation.

θmi θA (1-1-TA)
Fist... (1) According to the formula (1), the rate of change of the bearing temperature is given by the equation (1).

becomes.

In the above formula, t is time and TA is a time constant.

Further, when the cooling water temperature is B, the same calculation can be performed.

D6 Problems to be Solved by the Invention In the method described above, the rate of increase in bearing temperature is used as the standard for abnormality judgment, so if the bearing temperature suddenly rises during startup, abnormality judgment can be made based on speed and force. Although it is possible to determine abnormalities according to the condition, there is no consideration given to the lubricating oil cooling water temperature, which has a non-negligible effect on the bearing temperature. As a result, it has been impossible to accurately detect temperature abnormalities in bearings of generators, etc., which are used in places where there is a large difference in cooling water temperature between winter and winter.

The present invention has been made to solve the above-mentioned drawbacks.
@Provides a method to detect bearing temperature abnormalities based on bearing temperature and lubricating oil cooling water temperature, thereby making it possible to detect bearing temperature abnormalities over the entire temperature range in a short time) The purpose is to prevent disturbances such as temperature changes and to detect bearing temperature abnormalities with high accuracy.

Means and operation for solving the E0 problem The present invention, which solves the above-mentioned drawbacks, calculates the value obtained by multiplying the lubricating oil cooling water temperature by a constant n determined for each bearing structure and the bearing temperature. Determine the bearing conversion temperature, calculate the bearing evaluation temperature rise rate from this bearing conversion temperature, calculate the bearing temperature rise rate from the bearing temperature, and compare this bearing temperature rise rate with the bearing evaluation temperature rise car. If the temperature rise rate exceeds the bearing evaluation temperature increase rate at that time, it is considered as a bearing temperature abnormality.

F6 example An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a graph showing a bearing temperature abnormality detection method according to an embodiment of the present invention, FIG. 2 is a partial vertical cross-section of a thrust bearing of a vertical water turbine generator to which the method of the present invention is applied, and FIG. 3 is a graph showing the method according to the present invention. It is a flowchart which shows. The rotating shaft 1 of the thrust bearing is the rotor 2
A rotating member [thrust boss] 3 is integrally attached to the rotating shaft l. The circumferential surface of the rotating member 3 is a radial journal portion 4a, and an 11-ring-shaped rotating plate 5 is attached to the rotating member 3.
The lower surface of is a thrust journal portion 6. on the other hand,
The frame body 7 is provided with an oil tank 9 that accommodates the rotating plate 5 and the rotating member 3 and stores lubricating oil 8. A radial bearing (guide metal) 10 surrounding the radial journal part 4 is provided at the upper part of the oil tank 9, and oil 8 is supplied to the rotating member 3 between the radial journal part 4 and the radial bearing 1.
0 is provided with an oil guide hole 11 for guiding the oil between the two. A thrust bearing (sector metal) 12 facing the thrust journal portion 6 is fixed to the bottom of the oil tank 9, and the thrust bearing 121 is provided with a resistance thermometer (not shown). Also, oil W! Oil in 9 (this is a large number of cooling water pipes 1)
3 is a pipe (n) through which cooling water is passed, and a resistance thermometer (not shown) is installed on the artificial side of the cooling water pipe (13). 3 rotates, and the oil 8 is supplied between the radial journal part 4 and the radial bearing 10 through the oil guide pipe 11 and between the thrust journal part 6 and the thrust bearing 12 due to the centrifugal force.

As each bearing portion is cooled, the oil 8 used for cooling is cooled by water flowing through the cooling water pipe 13.

The temperature of the thrust bearing 12 and the cooling water is measured by a resistance thermometer installed on the inlet side of the thrust bearing 12 and the cooling water pipe 13.Based on the measured temperature, the bearing evaluation temperature rise rate is calculated as shown in the following formula. It is expressed as a function of bearing evaluation temperature θX, which is the bearing temperature plus cooling water temperature correction.

θX-θN-θCN-K(θCo-θcN)@″(5)
D Me A19X + B
-* (6) θXX axis bearing conversion temperature N2 Momentary bearing temperature θCNCN Previous cooling water temperature: Correction coefficient for cooling water temperature change θco: Initial value (reference value) cooling water temperature D = Bearing evaluation temperature increase rate A , B: Coefficient 1°C and constant determined by the size and structure of the bearing. Units are n= and =-0min respectively
mtn Note that the correction coefficient in equation (5) has different values depending on the bearing structure, its cooling structure, etc. In an example of a bearing for a water turbine generator, it is about 0.4 to 0.8.

If the value of K is prepared for each measured example of a different bearing structure, it is possible to estimate in advance the correction coefficient for the cooling water temperature change of a similar machine.

Using this formula (5) (63), the relationship between the bearing temperature rise rate for each of the cooling water temperatures A and B shown in Figure 6 and the bearing evaluation temperature θX is expressed as shown in Figure 1. In other words, even if there is a large difference in the cooling water temperature, the bearing temperature θ, θB
Since the characteristics are almost the same, the bearing evaluation temperature increase rate has approximately the same value with respect to the bearing conversion temperature θX, and an abnormality in the bearing temperature can be accurately detected.

It should be noted that even if there is a large difference of Δtc in the cooling water temperature, the error will be within the range of a very small difference ΔtBX, which is a natural result since the bearing temperatures θ^ and θB are substantially the same.

Next, specific abnormality detection will be explained with reference to the flowchart of FIG. First, the bearing temperature and the cooling water temperature are input to the computer, and the bearing evaluation temperature θX is calculated based on equation (5). From this bearing evaluation temperature θX, the bearing evaluation temperature increase rate is calculated based on equation (6). Further, when the actual bearing rate increase also increases, if the abnormality alarm is smaller than or equal to the change rate, the detection of the bearing temperature and cooling water temperature continues.

Although the above embodiment is applied to a bearing of a water turbine generator, the present invention is not limited to the above embodiment as long as the bearing is of a type in which the bearing lubricating oil is cooled with water.

G1 Effects of the Invention In the bearing temperature abnormality detection method according to the present invention, a bearing conversion temperature is obtained based on the bearing temperature and the cooling water temperature, a bearing evaluation temperature increase rate is calculated from this bearing conversion temperature, and the bearing evaluation temperature increase rate and the bearing evaluation temperature increase rate are calculated. Since an abnormality in the bearing temperature is detected by comparing the actual bearing temperature increase rate, an abnormality in the bearing temperature can be detected in a short time over the entire temperature range. Furthermore, disturbances such as changes in cooling water temperature are prevented, and bearing temperature abnormalities can be detected with high accuracy.

[Brief explanation of the drawing]

Fig. 1 is a graph showing a bearing temperature abnormality detection method according to an embodiment of the present invention, Fig. 2 is a partial vertical cross-sectional view of a thrust bearing of a vertical water turbine generator to which the method of the present invention is applied, and Fig. 3 is a graph showing the method of detecting an abnormality in bearing temperature according to an embodiment of the present invention. A flowchart showing the invention method, Fig. 4 is a graph showing a method for detecting abnormalities in bearing temperature by determining the maximum allowable temperature, and Fig. 5 shows a method for detecting abnormalities in bearing temperature based on the bearing temperature increase rate. The graph, Figure 6 is a graph showing the change in cooling water temperature and bearing temperature, and Figure 7 is the bearing temperature surface shown in Figure 6! 2 is a graph showing I as a relationship between temperature increase rate and bearing temperature. Inside the drawing. 1 is the rotation axis. 10 is a radial bearing. 12 is a thrust bearing. 13 is the cooling water pipe. θX is the bearing conversion temperature. D is the bearing evaluation temperature increase rate.

Claims (1)

[Claims] The bearing conversion temperature is determined based on the value obtained by multiplying the lubricating oil cooling water temperature by a constant determined for each bearing structure and the actual bearing temperature, and the bearing evaluation temperature increase rate is determined from the bearing conversion temperature. Determine the bearing temperature increase rate from the temperature, compare the bearing temperature increase rate with the bearing evaluation temperature increase rate, and determine that the bearing temperature is abnormal if the bearing temperature increase rate becomes higher than the bearing evaluation temperature increase rate. A bearing temperature abnormality detection method characterized by: