JPH0455255B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field to Which the Invention Pertains] The present invention relates to rubbing, in which a rotating member and a stationary member abnormally rub against each other during operation of a rotating machine.
The present invention relates to a rubbing detection device that detects phenomena based on acoustic vibrations, and particularly to a device configuration that can improve detection accuracy without being affected by collision vibrations synchronized with the rotation of a rotating member.

[Prior art and its problems]

If a rubbing phenomenon occurs during operation of a rotating machine such as a steam turbine or a generator, abnormal vibrations may occur, making it impossible to continue operation or leading to a serious accident. In particular, in thermal machines such as steam turbines, even though the gap between rotating and stationary members is narrow, thermal deformation is likely to occur in component parts such as the casing due to temperature rise, so rubbing phenomena are likely to occur. be. Therefore, it is necessary to detect the rubbing phenomenon at an early stage and prevent the rubbing from progressing by operating the rotating machine, such as by lowering the rotational speed, the temperature of the injected steam, and the amount of steam. The rubbing phenomenon is usually detected by detecting the acoustic vibrations generated in rotating machinery due to rubbing (hereinafter, these vibrations may be referred to as rubbing vibrations), and this rubbing vibration occurs in synchronization with the rotation of the rotating parts. There is a characteristic that

Figure 4 is a configuration diagram of a conventional rubbing detection device.
In the figure, 1a, 1b, 1c, and 1d are respectively the rotating shaft, casing, bearing metal, and bearing cover of the rotating machine 1, 1e is a rotating body that is fixed to the rotating shaft 1a and rotates inside the casing 1b, and 2a has a bearing metal at one end. 1
It is a linear wave guide fixed to c and an acoustic sensor 2 fixed to the other end. The acoustic sensor 2 is an acoustic emission sensor (hereinafter referred to as AE) that uses a piezoelectric element and is formed to have a resonance frequency in a high frequency range.
(sometimes called a sensor), the waveguide 2
a is the vibration of the bearing metal 1c whose one end is fixed.
It has a function of transmitting information to the AE sensor 2. The output signal 2b of the AE sensor 2 corresponds to the acceleration of vibration occurring in the portion of the bearing metal 1c to which the wave guide 2a is attached. wave guide 2
a is the outside of the bearing cover 1d where the inside is high temperature.
It is provided to facilitate the placement of the AE sensor 2 and the maintenance of the sensor 2. 3 is the rotating shaft 1a
This is a pulse generator that outputs a pulse signal 3a synchronized with the rotation of the motor. 4 is an amplifier that amplifies the output signal 2b; 5 is a bandpass filter that receives the output signal 4a of the amplifier and extracts the dominant frequency component of the rubbing vibration from this input signal to improve the S/N ratio; 6 is a bandpass filter of the filter 5; This is a detector that performs envelope detection of the output signal 5a. 7 is an average value that uses the output signal 3a of the pulse generator 3 as a trigger signal, performs time average calculation for a predetermined time on the output signal 6a of the detector 6, and outputs a signal 7a according to the calculation result. Since the arithmetic unit 7 is configured in this way, the output signal 7a of this arithmetic unit is included in the output signal 6a of the detector and is the pulse signal 3a.
This is a signal from which unsynchronized white noise has been removed. 8 observes signals 7a and 3a
It is a CRT display.

In FIG. 4, each part is configured as described above, so if a rubbing phenomenon occurs between the rotating body 1e and the casing 1b in the rotating machine 1, for example, the rubbing vibration caused by this phenomenon 1
00 is propagated to the bearing metal 1c via the rotating body 1e and the rotating shaft 1a in order, and as a result, the waveform of the output signal of the main part becomes as shown in FIG. 5, for example. In FIG. 5, the horizontal axis of each waveform diagram indicates elapsed time, and arrow P indicates that rubbing vibration occurs near the time indicated by this arrow.
In Fig. 5, when there is no rubbing vibration, the output signal 2b of the AE sensor consists of only white noise because no rubbing phenomenon has occurred, and when there is rubbing vibration, the rubbing phenomenon is not occurring. This shows a case where the signal 2b is composed of white noise and rubbing vibration. When the rubbing phenomenon occurs, as mentioned above, rubbing vibrations synchronized with the rotation of the rotating member occur,
FIG. 5 shows that as a result, triangular pulse-like rubbing vibrations appeared in the signals 6a and 7a. As mentioned above, in FIG. 4, when a rubbing phenomenon occurs, a triangular pulse-like rubbing vibration appears in the signals 6a and 7a, so by comparing this vibration with the output signal 3a of the pulse generator and observing it, the rubbing The occurrence of a phenomenon can be detected with high accuracy, and when the signal 7a is used for this detection, the detection work becomes easier because the signal 7a has less white noise than the signal 6a.

Although the detection device shown in FIG. 4 detects the occurrence of a rubbing phenomenon as described above, this rubbing detection device has the following problems. In other words, FIG. 6 is an enlarged perspective view of the main parts in FIG.
In FIG. 6, the bearing metal 1c is formed into a ring shape by tightening an upper metal 101 and a lower metal 102 with bolts 103, and the lower metal 102 is formed into a ring shape by tightening the upper metal 101 and the lower metal 102 with the bearing seat 1f.
It is placed on the seat 1f so as to be in contact with the seat 1f. The side surface of the lower metal 102 and the surface of the bearing seat 1f, which normally come into contact with each other, are formed in a spherical shape, and the side surface of the lower metal 102 and the surface of the bearing seat 1f are formed on this spherical contact surface.
There is an arc-shaped gap 1 at the part where the top surface almost starts to touch.
04 is usually formed. In FIG. 6, since the bearing metal 1c and the bearing seat 1f are constructed as described above, when the rotating shaft 1a rotates, various types of excitation such as centrifugal force due to residual unbalance of the rotating members including the shaft 1a are generated. Forces act on the bearing metal 1c, and depending on the magnitude of these excitation forces and the manner in which the gap 104 is formed, the bearing metal 1c and the bearing seat 1f may collide, resulting in collision vibration 105.

FIG. 7 is an explanatory diagram of signal waveforms of the main parts of the rubbing detection device in FIG. 4 when such a collision vibration 105 occurs.
The signals 6a and 7 are generated in synchronization with the rotation of
It appears as a triangular pulse-like waveform as shown by arrow Q in a. Therefore, when such vibration 105 occurs, the rubbing detection device shown in FIG. 4 has a problem in that it cannot distinguish between the collision vibration 105 and the rubbing vibration.

[Purpose of the invention]

The present invention solves the problems of conventional rubbing detection devices as described above, and provides a rubbing detection device that can reliably perform detection operations without being affected by collision vibrations that occur in synchronization with rotation. The purpose is to

[Key points of the invention]

In order to achieve the above object, the present invention includes first and second acoustic sensors that detect vibrations of a bearing metal and a bearing seat that are in contact with each other, and the first and second acoustic sensors.
an amplifier that amplifies each output signal of the acoustic sensor; a bandpass filter that reduces noise in each output signal from the amplifier; and a detector that performs envelope detection of each output signal from the bandpass filter; A rubbing detection device is configured with a signal processing unit that performs arithmetic processing on each output signal from the detector, and a rubbing phenomenon is detected based on the output signal of the signal processing unit. In this way, when a collision occurs between the first part and the second part in synchronization with the rotation of the rotating machine, the collision vibration signals output from both acoustic sensors are canceled out by the signal processing unit.
In this way, it is possible to obtain a rubbing detection device that can reliably perform a detection operation without being affected by such collision vibrations.

[Embodiments of the invention]

FIG. 1 is a configuration diagram of a first embodiment of the present invention, and the main body of a rotating machine 1 including a casing and the like is omitted in this figure. In Fig. 1, 10 and 11 are both AE sensors similar to those shown in Fig. 4.
The AE sensors 10 and 11 each have a waveguide 10 similar to the waveguide 2a in FIG.
It is attached to the lower metal part 102 and the bearing seat 1f via a and 11a, and is installed outside the bearing cover 1d. Both AE sensors 10 and 11 have substantially equal vibration sensitivity characteristics, and in this case, the output signal of the AE sensor 10 is input to the amplifier 4. 1
2 is an amplifier that receives the output signal of the AE sensor 11, amplifies the signal, and outputs it as an output signal 12a; 13 has the same function as the bandpass filter 5, which receives the signal 12a and inputs the output signal to the detector 14; The detector 14 is a bandpass filter having
Similarly to the wave detector 6, the wave detector performs envelope detection on the input signal and outputs an output signal 14a. The output signals 6a and 14a from both detectors are both input to a differential amplifier 15, where a signal 15a corresponding to the difference between the two signals is formed and input to an average value calculator 7. 21 is the rotating shaft 1a and the bearing metal 1c
This is a rubbing detection device consisting of the parts shown in the figure except for the bearing cover 1d and the bearing seat 1f.

Next, the operation of the main parts of the rubbing detection device 21 will be explained with reference to the waveform explanatory diagram of FIG. Second
In the figure, first of all, assuming that no rubbing phenomenon occurs and only collision vibration exists due to the collision between the lower ring 102 and the bearing seat 1f, the AE sensor 1
Each of the output signals 0 and 11, and therefore the output signals 4a and 12a of the amplifier, are each composed of a collision vibration signal synchronized with the rotation of the rotating machine 1 and white noise,
In this case, the sensors 10 and 11 each have a lower metal 10
2. Since it is installed to detect each vibration of the bearing seat 1f, the levels of the collision vibration signals in both signals 4a and 12a are almost the same, but most of the white noise is transmitted through the rotating shaft 1a. This is a noise accompanying the rotation of the rotating shaft 1a, so when this noise is transmitted to the bearing seat 1f, it is attenuated at the contact portion between the lower metal part 102 and the bearing seat 1f, and therefore the signals 4a, The level of each white noise in 12a is usually higher in the former. The triangular pulse-like waveform indicated by Q in the waveforms of the detector output signals 6a and 14a indicates the collision vibration in this case, and in this case, as is clear from the above, the signals 6a and 14a
Since the levels of the collision vibration pulses at are almost equal, the output signal 15a of the differential amplifier becomes a white noise-like signal without a pulse-like waveform.

Next, if the collision vibration caused by the collision between the lower metal 102 and the bearing seat 1f and the rubbing vibration propagated via the rotating shaft 1a exist simultaneously, in this case, the white noise waveform in the signals 4a, 12a or 6a, 14a , each aspect of the collision vibration waveform is the same as in the case where there is no rubbing vibration and only collision vibration is present, but signals 6a and 14a both have a triangular pulse-like waveform based on the rubbing vibration at the time indicated by the P arrow. appear. However, in this case, the inventor discovered that due to the vibration damping effect at the abutting portion between the lower metal 102 and the bearing seat 1f, the level of the rubbing vibration pulse in the signal 14a is lower than that of the rubbing vibration pulse in the signal 6a corresponding to this pulse. We have found that the level is significantly lower than that of
As a result, the signal 14a has a waveform dominated by collision vibration. Therefore, only the triangular pulse based on the rubbing vibration appears in the output signal 15a of the differential amplifier in synchronization with the output signal 3a of the pulse generator, and the triangular pulse based on the collision vibration does not appear. This allows confirmation of the occurrence of the rubbing phenomenon.

The rubbing detection device 21 shown in FIG. 1 can perform rubbing detection as described above. Therefore, such a detection device 21 is a rubbing detection device that can reliably detect a rubbing phenomenon without being affected by vibrations caused by periodic collisions between the bearing metal 1c and the bearing seat 1f.

FIG. 3 is a block diagram of a second embodiment of the present invention, and the main differences from FIG. 1 are that the pulse generator 3 is not provided and the signal processing mode after the detectors 6 and 14. The difference is that In Figure 3, 1
The output signals 6a and 14a of the detector are inputted to 6 and 17, respectively, and the DC component of these input signals, that is, the white noise equivalent component is removed to produce an output signal 16.
The filters 16 and 17 are high-pass filters that output signals a and 17a, and have substantially the same characteristics. 18 is a divider which receives signals 16a and 17a and outputs a signal 18a according to the level ratio of both signals, and the signal 18a is inputted to a comparator 19, where the value of the signal 18a is equal to or higher than a predetermined value. This signal is output from the comparator 19, and the alarm 20 is activated. In FIG. 3, the filters 16, 17 and the divider 18 are configured as described above, so in this case the divider 18 calculates the ratio of the levels of the fluctuating components contained in the detector output signals 6a, 14a. Furthermore, the inventor has experimentally found that when the levels of the signals 16a and 17a are A and B, respectively (A/B), it can be considered that a rubbing phenomenon occurs. Therefore, in Fig. 3, the comparator 19
By setting the predetermined value in , to a value corresponding to 3, the rubbing phenomenon can be automatically detected. In the case of FIG. 3, even if the collision vibration described in FIG. It is clear that the operation of the comparator 19 is not affected.
Therefore, the second embodiment shown in FIG. 3 is capable of reliably detecting the rubbing phenomenon without being affected by the collision vibration that occurs in synchronization with the rotation of the rotating machine due to the collision between the bearing metal and the bearing seat. This is a rubbing detection device that can perform

In each of the above embodiments, the AE sensor 10,
11 are arranged to detect each vibration of the bearing metal 1c and the bearing seat 1f, respectively, so that rubbing detection can be performed without being affected by the collision vibration generated between the bearing metal and the bearing seat. However, in the present invention, the sensors 10 and 11 are connected to the first and second parts of a rotating machine, which are likely to come into contact with each other and generate collision vibrations.
The device may be arranged to detect vibrations from each of the parts.

[Effect of occurrence]

As described above, in the present invention, the first sensor detects the vibrations of the bearing ring and the bearing seat of the rotating machine, which may come into contact with each other and generate collision vibrations.
and a second acoustic sensor, an amplifier that amplifies each output signal of both of these acoustic sensors, a bandpass filter that reduces noise in each output signal from the amplifier, and each output signal from the bandpass filter. A rubbing detection device is composed of a detector that performs envelope detection of the detector and a signal processing unit that performs arithmetic processing on each output signal from the detector, and detects a rubbing phenomenon based on the output signal of the signal processing unit. With this configuration, when a collision occurs between the bearing metal and the bearing seat in synchronization with the rotation of the rotating machine, the collision vibration signals output from both acoustic sensors are transmitted to the signal processing section. As a result, it is possible to obtain a rubbing detection device that can reliably perform a detection operation without being affected by vibrations caused by the collision.

[Brief explanation of drawings]

1 and 3 are configuration diagrams of the first and second embodiments of the present invention, respectively, FIG. 2 is an explanatory diagram of signal waveforms of the main parts in FIG. 1, and FIG. 4 is the configuration of a conventional rubbing detection device. Fig. 5 is an explanatory diagram of signal waveforms of the main parts in Fig. 4, Fig. 6 is an enlarged perspective view of the main parts in Fig. 4, and Fig. 7 is an explanatory diagram of signal waveforms of the main parts in Fig. 4. 5 is a waveform explanatory diagram different from FIG. 5. FIG. 1... Rotating machine, 1c... Bearing metal, 1f... Bearing seat, 10, 11... AE sensor.

Claims (1)

[Claims] 1. First and second acoustic sensors that have substantially equal vibration sensitivity characteristics and detect vibrations of a bearing ring and a bearing seat that abut each other in a rotating machine, and the first and second acoustic sensors. an amplifier that amplifies each output signal of the amplifier, and a bandpass filter that reduces noise of each output signal from the amplifier;
It consists of a detector that performs envelope detection of each output signal from the bandpass filter, and a signal processing unit that performs arithmetic processing of each output signal from the detector, and the output signal of the signal processing unit is used to detect the rotating machine. A rubbing detection device characterized by detecting a rubbing phenomenon. 2. In the detection device according to claim 1, the signal processing section includes an average value calculator that outputs a signal according to the difference between the respective output signals from the respective detectors corresponding to the first and second acoustic sensors. A rubbing detection device comprising: 3. In the detection device according to claim 1, the signal processing section includes a divider that outputs a signal according to the ratio of each output signal from the respective detectors corresponding to the first and second acoustic sensors. A rubbing detection device comprising: