JP2001227935A - Apparatus for predicting abnormality of journal bearing of large rotating machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inform the replacement time of a journal bearing of a large rotating machine in operation by sharply detecting any abnormal state of the bearing by means of an apparatus enabling the machine to be installed without being dismantled to a large extent. SOLUTION: A scanning-ultrasonic-probe assembly 51 in which a plurality of scanning ultrasonic probes 2 are interconnected by elastic bodies 52 is installed outside of the bearing to detect the reflection time of an ultrasonic wave which is shortened by separation at the surfaces of contact between a boss 41 and a bush 42 and by the wear of the bush 42, and variations in the strength of reflected waves which is reduced by the wear and the separation, so as to predict the abnormal state of sliding parts.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for diagnosing the condition of a journal bearing in a large rotating machine, and more particularly to a diagnostic apparatus capable of diagnosing the state of a bearing during rotation.

[0002]

2. Description of the Related Art Generally, large rotating machines are provided with bearings for supporting a rotating shaft. This bearing has a structure that receives the entire load of the rotating shaft, and a sliding journal bearing is often used. Such a sliding journal bearing is composed of a cylindrical bearing body (boss) and a flat bearing (bushing) joined to the inner peripheral surface thereof, and a space between the rotating shaft surface and the bushing surface is filled with lubricating oil. In motion.

[0003] During the operation of such a sliding journal bearing, peeling at the joint between the boss and the bush causes wear or damage of the bearing surface material, resulting in a failure stop of the whole machine.

Conventionally, in order to measure the peeling state at the joint between the boss and the bush, the operation of the machine is periodically stopped, and the bearing portion is disassembled or observed, or the mechanical measurement is performed. Had gone. For this reason, in the event of a failure, it was difficult to quickly identify the cause and repair the same, and it was not possible to detect the state of damage on the bush surface due to sudden entry of foreign matter. Extensive disassembly was a heavy burden on inspectors. Further, as a means for detecting the state of the bearing, a method of measuring the bush thickness using ultrasonic waves as disclosed in Japanese Patent Application Laid-Open No. 5-34135 is known. However, it has been very difficult to attach a measuring device to a bearing body whose surroundings are mostly covered with a holder, and to measure the entire bearing in a non-uniform damaged state such as a peeled state.

[0005]

SUMMARY OF THE INVENTION The present invention has been made as a solution to the above circumstances. Its purpose is that it can be installed without significant dismantling work,
Moreover, the peeling state of the joint between the boss and the bush, the abrasion state of the bushing material, and the surface damage state of the bushing, which occur in the journal bearing, are measured over a wide area of the bearing while the rotating machine is operated. It is an object of the present invention to provide a sliding journal bearing abnormality prediction device capable of predicting a decrease in the reliability of a journal bearing in advance.

[0006]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a scanning ultrasonic probe capable of arbitrarily scanning the transmitting and receiving direction of a sound signal on a journal bearing of a large rotating machine. Predict failure of the whole machine by detecting the peeling state at the joint surface between the boss and the bush, the abrasion state of the bush material, and the damage state of the bush surface by measuring the reflection time of the sound wave and the reflected wave intensity. It is in.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be specifically described below with reference to FIGS.

FIG. 1 is a block diagram showing the configuration of a device for predicting abnormality of a sliding journal bearing according to the present embodiment. As shown in this figure, the abnormality predicting device in the present embodiment is configured by a sliding journal bearing as a subject, a scanning ultrasonic probe 2, a measuring circuit 3, a judging circuit 4, an ultrasonic imaging device 5, and an alarm 6. Have been. Outer peripheral surface of a journal bearing boss to be measured by the scanning ultrasonic probe 2,
Alternatively, it is fixed to an end or the like. The scanning ultrasonic probe 2 has a function of emitting an ultrasonic pulse inside the bearing according to a control signal from the measurement circuit 3 and receiving the ultrasonic wave reflected back inside the bearing. Further, it has a function of scanning the transmitting direction and the receiving direction of the ultrasonic pulse one-dimensionally or two-dimensionally. The transmitted ultrasonic pulse is reflected at the interface between the rotating shaft surface and the bush surface or at the peeling point at the joint between the bush and the boss, and is received by the scanning ultrasonic probe 2 when returning.

The measuring circuit measures the reflection time, which is the time from transmission of an ultrasonic pulse at each scanning angle until reception of the reflected wave, and the reflected wave intensity, which is the magnitude of the amplitude of the reflected wave. The reflection time obtained by these measurement circuits,
Information on the reflected wave intensity and the scanning angle at that time is sent to the ultrasonic imaging device 5 and displayed on the display unit as a sector-shaped cross-sectional image of the subject via the display circuit.

On the other hand, the measurement result by the measurement circuit 3 is also transmitted to the judgment circuit 4, and when the measured reflection time and the absolute value of the reflected wave intensity exceed the predetermined values, or when the past value and the present value are used. If the change in the reflection time and the reflected wave intensity per unit time obtained exceeds another predetermined value, it is determined that the bearing is in an abnormal state, and a signal notifying the bearing replacement time is turned on in the alarm 6. The remaining life of the bearing is predicted as a linear function from the amount of change in the reflection time per time, and different types of signals corresponding to the remaining life are lit on the alarm 6.

FIG. 2 shows a horizontal axis type hydroelectric generator to which the apparatus of the present invention as shown in FIG. 1 is applied. The water flow introduced from the introduction passage 21 causes the rotating shaft 22 to rotate in the rotating wing portion 23 attached to the end of the rotating shaft 22 by contact with the rotating wings, and is discharged from the discharging passage 25 to the outside. The rotating force generated on the rotating shaft 22 rotates the rotor in the power generation unit 26 composed of the rotor and the stator attached near the center of the rotating shaft 22, and generates an electromotive force between the rotor and the stator installed on the outer periphery thereof. Generate. Rotary axis 2
Reference numeral 2 is supported by a sliding journal bearing 1 installed near both ends of the rotor mounting portion.

As shown in FIGS. 3 (a) and 3 (b), a plurality of scanning ultrasonic probes 2 are connected into a deformable rod shape using an elastic body 52 to form a scanning ultrasonic probe assembly 51. I do. Since the center of the outer peripheral surface of the journal bearing 28 is covered and fixed by the bearing jig 30, it is difficult to secure an area for mounting the sensor. For this reason, the scanning ultrasonic probe assembly 51 is fixed circumferentially at both ends of the outer peripheral surface of the journal bearing 28 by using a mounting jig and an insulating adhesive or a wire with the sensor surface facing the axial center direction. .

The signal cable 32 from the scanning ultrasonic probe assembly 51 is taken out of the bearing and connected to the measuring circuit 3. Inside each scanning ultrasonic probe 2 in the scanning ultrasonic probe assembly 51, there are many small ultrasonic transducers each having a 1 mm square cross section and capable of transmitting and receiving 10 MHz ultrasonic pulses. The child corresponds to one ultrasonic transmission / reception angle. These transducers are sequentially operated by a signal from the measurement circuit 3 to perform one-dimensional or two-dimensional scanning as shown in FIG. 4 and to perform ultrasonic scanning at each scanning angle within a maximum range of 140 °. Transmission and reception.

The measuring circuit 3 includes the scanning ultrasonic probe 2
To output the ultrasonic reflection time, reflected wave intensity, and scanning angle at each scanning angle to the determination circuit 4 and the ultrasonic imaging device 5. The ultrasonic imaging apparatus 5 receives a signal from the measurement circuit 3 and transmits the signal to an internal display circuit 60.
The determination circuit 4 receives the signal from the measurement circuit 3 and compares the reflection time with a predetermined value for the ultrasonic wave having a certain threshold or more obtained at each scanning angle, and determines the reflection time. If an area shorter than the value occurs, it is determined that peeling has occurred at the joint surface between the boss and the bush, and a signal notifying the occurrence of a bearing abnormality is illuminated on the alarm 6.

On the other hand, the display circuit 60 determines the ultrasonic reflection time,
From the intensity of the reflected wave and the scanning angle at that time, a sectional image in the scanning range on the sector is output to the monitor 61 in a two-dimensional manner. Ultrasonic waves transmitted through the bearing generally have an interface 71 between the bush surface and the rotating shaft surface, a peeling portion 70 at the interface between the boss and the bush,
Alternatively, the light is reflected at a crack in the bearing. In this cross-sectional image, a place where the ultrasonic wave is determined based on the reflection time and the scanning angle is displayed. Picture 7 of
5, the reflection at the peeling portion 70 at the joint surface between the boss and the bush appears as an image 76. If peeling occurs from this image, the location can be visually specified.

As shown in FIGS. 3 (a) and 3 (b), the scanning ultrasonic probe assembly 51 is formed so as to be freely deformable.
And can be fixed by winding it around the bearing in a cylindrical shape.
In this case, the scanning ultrasonic probe 2 is installed so as to scan in parallel to the axis with the sensor surface facing the center as shown in FIG. 6B. On the other hand, the scanning ultrasonic probe assembly 51
Is deformed into a cylindrical shape and fixed to the end face of the bearing as shown in FIG. 7A, the scanning ultrasonic probe 2 has the sensor surface oriented in a direction perpendicular to the axis as shown in FIG. It is installed so as to perform scanning along the radial direction. When the bearing is long, a wider range of measurement can be performed by fixing the scanning ultrasonic probe assembly 51 to both ends of the bearing. In addition, since it can be deformed into a semicircle or a free curved shape according to the available space around the bearing and the surrounding area and installed at the required location, the bearing included in the rotating machine already in use Can be easily installed. Alternatively, the scanning ultrasonic probe 2 may be connected in a semi-cylindrical or cylindrical shape with the elastic body 52 before use.

The determination of the peeling state at the interface between the boss and the bush by the determination circuit 4 is performed as follows. FIG. 8A shows an example of a measurement result when no peeling has occurred.
As shown in this figure, when no peeling has occurred,
Ultrasonic pulses emitted from the scanning ultrasonic probe 2 propagate through the inside of the boss 41, and most of them generate reflected waves at the interface 71 between the bush surface and the rotating shaft surface. FIG.
(B) shows an example of a measurement result when peeling occurs.
Similarly, the ultrasonic pulse propagates through the inside of the boss 41. However, when the ultrasonic pulse hits the separation portion 70 where the acoustic impedance changes greatly, a reflected wave is generated there.

In the measuring circuit 3, the reflection time of the ultrasonic wave obtained from the reflected wave from the separation portion 70 is the reflection time obtained from the reflection wave from the interface 71 between the bush surface and the rotating shaft surface when there is no separation. If this time difference is detected, it is determined that a peeling state exists at the scanning position. If the absolute value of the time difference exceeds a predetermined value as a result of the comparison, it is determined to be an abnormal value, and a signal notifying the bearing 6 of the time for replacing the bearing is sent to the alarm 6. On the other hand, since the intensity of the ultrasonic wave reaching the bush surface is reduced by the amount reflected on the way by the peeling portion 70,
The intensity of the reflected wave at the interface between the bushing surface and the rotating shaft surface also decreases.

On the other hand, the determination of the abrasion state of the bush is performed as follows. When the bush 42 is worn as shown in FIG. 9B, the thickness is smaller than when the bush 42 is not worn as shown in FIG. 9A. The reflection time of the ultrasonic wave reflected at the interface 71 with the surface is shortened as a whole. That is,
Since the reflection time of an ultrasonic wave depends on its transmission distance,
The shorter the transmission distance due to wear, the shorter the reflection time.
The wear state of the bush 42 can be measured from the decrease in the reflection time. As a result of the comparison, if the measured reflection time is shorter than a predetermined reflection time, it is determined that the amount of abnormal wear has occurred, and a signal is sent to the alarm 6 to inform the alarm 6 of the time to replace the bearing.

The determination of the peeling state at the joint surface between the boss and the bush and the determination of the abrasion state of the bush are both measured using the reflection time of the ultrasonic wave. Different, this 2
The two decisions are made separately. The reflection time at the peeling portion of the joint surface between the boss and the bush is always shorter than the reflection time at the interface between the bush surface and the rotating shaft surface, and has a determined value. On the other hand, the change in the reflection time due to the abrasion of the bushing has the property of gradually changing over time.

Further, if foreign matter enters the space between the rotating shaft surface and the bushing surface, etc., the bushing surface may be damaged such as a scratch, or if the roughness becomes large, the peak of the intensity of the reflected wave measured is measured. Are dispersed, and the state of damage on the bush surface can be known from the dispersed state.

The determination circuit 3 records the past measurement results, and calculates the amount of change in the reflection time per unit time by comparing with the latest measurement results. Then, at the present stage, the remaining bearing life when the change amount of the reflection time per unit time at that time is used is calculated, and a separate signal corresponding to the value is transmitted to the alarm 6. In this embodiment, the remaining life is expected to be one year or more,
Judgment is made in three stages, that is, when the remaining life is predicted to be 90 days or more, and when the remaining life is less than 90 days and it is time to replace the bearing, and three different alarms that indicate the approximate remaining life are turned on. If the absolute value of the amount of change in the reflection time per unit time becomes larger than a predetermined threshold value, it is determined that the damage to the bearing is rapidly progressing, and the time for replacing the bearing is determined. A signal is transmitted to the alarm 6.
As described above, by using the movement of the amount of change in the reflection time per unit time for the prediction of the remaining life and the determination of the bearing replacement time, it is possible to cope with a slow change and a fast change in the progress of the separation and wear of the bearing. It is possible to predict an abnormality of the sliding bearing at an early stage.

When the surface of the object to be measured is large, or when it is difficult to obtain sufficient contact with the surface of the scanning ultrasonic probe because the surface shape is curved and complicated, the object to be measured is Propagation of ultrasonic waves to the laser is likely to be hindered. In this case, by interposing a liquid between the surface of the probe and the surface of the object to be measured, the transfer characteristics can be greatly improved as compared with the case where the liquid is installed in a dry state as shown in FIG. As shown in FIG. 10 (b), a seal portion 53 is provided on the elastic body 52 for connecting the probe, or FIG.
By adopting a structure such as providing a seal member 54 around the probe as shown in FIG. 10 (c) or FIG. 10 (d), the liquid 55 can be scanned for a long period of time even in any installation posture of the scanning ultrasonic probe assembly 51. The measurement can be held in the vicinity of the ultrasonic probe 2 and stable and highly sensitive measurement can be performed. Further, although not shown, by providing an oil supply hole provided with a check valve and an air vent hole in the seal member 54, liquid can be sealed without mixing bubbles.

[0024]

As described above, according to the abnormality predicting apparatus of the present invention, the rotating machine is operated while the bearing is in the separated state at the joint surface between the boss and the bush, the worn state of the bush, and the damaged state of the bush. , And it is possible to predict future bearing errors. In addition, the existing rotating machine can be attached without being dismantled greatly, and the burden on the operator who has been forced to perform the conventional dismantling work is greatly reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an abnormality prediction device according to the present invention.

FIG. 2 is a schematic view showing a horizontal axis type hydroelectric power generation device embodying the present invention.

FIG. 3 is a schematic diagram showing a configuration of a scanning ultrasonic probe assembly.

FIG. 4 is a diagram showing a transmission / reception mechanism of an ultrasonic wave by a scanning ultrasonic probe.

FIG. 5 is a diagram showing an example of a cross-sectional image displayed on a monitor of the ultrasonic imaging apparatus.

FIG. 6 is a diagram showing an example in which a scanning ultrasonic probe assembly is provided on the outer periphery of a bearing.

FIG. 7 is a diagram showing an example in which a scanning ultrasonic probe assembly is provided on a bearing end surface.

FIG. 8 is a diagram showing a method of determining a peeling state using ultrasonic waves.

FIG. 9 is a diagram showing a method of determining a wear state of a bush using ultrasonic waves.

FIG. 10 is a diagram showing a method for holding a liquid near a scanning ultrasonic probe.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Sliding journal bearing part, 2 ... Scanning ultrasonic probe, 3 ... Measurement circuit, 4 ... Determination circuit, 5 ... Ultrasonic imaging apparatus, 6 ... Alarm, 21 ... Introduction path, 22 ... Rotary axis, 23
... Rotating blade part, 25 ... Discharge path, 26 ... Power generation part, 30 ... Bearing jig, 32 ... Signal cable, 41 ... Boss, 42 ... Bushing, 51 ... Scanning ultrasonic probe assembly, 52 ... Elastic body, 53 ... Seal part, 54 ... seal member, 55 ... liquid,
Reference numeral 60: display circuit, 61: monitor, 70: peeling part, 71:
A joining surface between the boss and the bush, 75... An image based on the reflected ultrasonic wave at the interface between the bush and the rotating shaft, and 76. An image based on the reflected ultrasonic wave at the peeling portion.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification FI FI Theme Court ゛ (Reference) G01N 29/06 G01N 29/06 29/10 504 29/10 504 (72) Inventor Yoichi Inoue Tsuchiura, Ibaraki 502 Kandachicho F-term in Machinery Research Laboratories, Hitachi, Ltd. F-term (reference) DA02 EA13 EA19 3J011 AA20 BA02 EA10 KA02

Claims (1)

[Claims] An apparatus has a function of generating an ultrasonic wave according to an applied voltage, receiving a sound wave reflected from an object to be measured and converting it into an electric signal, and freely scanning a transmission / reception direction of the sound wave. A scanning ultrasonic probe that can be used, a reflection time that is a time until the ultrasonic wave emitted by the probe is reflected at the object interface and returns to the probe again, and the intensity of the reflected wave at that time. An abnormality of a journal bearing in a large rotating machine, comprising: a measurement circuit for measuring; and a determination circuit for determining a peeling state at a joint between the bearing body and the flat bearing based on a signal from the measurement circuit. Forecasting device.