JPH04161829A - Detecting method for abnormality of bearing of body of rotation - Google Patents

Abstract

PURPOSE:To detect the abnormality of a bearing readily by comparing the fluctuating amounts of the time differences of the generating timings between pulses corresponding to the specified rotational positions among the phase-pulse trains of a rotary encoder having multiple-phase outputs with respect to the elapse of time. CONSTITUTION:A rotary shaft 52 is supported with a main body 51 in rotary encoder 5, and a rotary slit plate 54 is fixed to the shaft 52 in this constitution. Light which has passed through the rotating slit plate 54 passes through slits 56a-56c in each phase in a fixed slit plate 56. The light beams having the patterns for the respective phases are sent into light receiving sensors 57a-57c. Thus, the pulse trains corresponding to the respective phases are outputted from the light receiving sensors 57a-57c. The pulse trains are used, and the rotation angle and the rotational speed of the rotary shaft 52 are detected. The pulse trains of the encoder 5 are analyzed in an abnormality detecting circuit 6, and the abnormality and the deterioration of the bearing are detected.

Description

[Detailed Description of the Invention] [Industrial Field of Application] This invention detects an aperiodic component of the rotation shaft runout of a rotary encoder, and thereby detects an abnormality or deterioration of the bearing of the rotating body. Regarding the method.

[Prior Art] Generally, a rotating shaft of a rotating body, such as a motor or a spindle, is supported by a ball bearing, an air bearing, a magnetic bearing, a magnetic fluid bearing, or the like. The rotational shaft of a rotating body supported by such a bearing has eccentricity due to rotation. The eccentricity of the rotating shaft may increase as the rotating body is used, and this eccentricity is often caused by deterioration or abnormality of the bearing.

Such eccentricity of the rotating shaft includes a periodic component that is synchronized with the rotation period and an aperiodic component that is not synchronized, and it is important to detect these components in order to know the rotation status of the rotating body. In particular, detection of non-periodic components is very effective in detecting slight mechanical abnormalities in bearings and abnormalities in control systems.

Conventionally, in order to detect deterioration and abnormalities in the bearings of rotating bodies,
Equipped with an accelerometer or vibration meter on the rotating body or its support,
Is it something that detects the vibrations and checks for abnormal vibrations?
Alternatively, there is a method of detecting surface acoustic waves from the bearing to check for cracks or flaws, such as a method of using an acoustic emission sensor (hereinafter abbreviated as AE sensor), or a method of detecting the occurrence of an abnormality using the human ear. etc. are used.

[Invention tries to solve III! ] However, conventional methods for detecting abnormalities in rotating body bearings, for example, when using an accelerometer or a vibration meter, or when using an AE sensor, have the following drawbacks.

First, in order to detect minute deterioration or abnormalities in bearings, it is necessary to use expensive sensors, and their sensitivity and responsiveness cannot be said to be sufficient.

In addition, in the method of detecting the occurrence of an abnormality using the human ear,
It was not possible to detect minute deterioration or abnormalities in the bearing.

The purpose of this invention is to solve these drawbacks, and its purpose is to use pulses from a rotary encoder with multi-phase outputs attached to the rotating shaft of a rotating body. An object of the present invention is to provide a method for detecting an abnormality in a rotating body bearing that can detect abnormalities and deterioration.

[Means for Solving the Problem] In order to solve the problem, the method for detecting abnormality in a rotating body bearing of the present invention provides a method for detecting an abnormality in a rotating body bearing, which is mounted so as to rotate in synchronization with the rotating shaft of a rotating body supported by the bearing. The pulses of each phase are generated by the rotation of a rotary encoder with multi-phase output.
Among the pulse trains of each phase, the generation timing between specific pulses of each phase that occur corresponding to a predetermined rotational position of the rotary shaft of the rotary encoder is detected for each rotation, and the amount of variation in the time difference between the generation timings is detected. The present invention is characterized in that an abnormality in the bearing of the rotating body is detected by comparing the values over time.

[Operation] In this invention, a rotary encoder having a multiphase output that is attached to rotate in synchronization with the rotation axis of a rotary body is used, and a predetermined rotational position is used in the pulse train of each phase generated by the rotary encoder. An abnormality in the bearing of the rotating body is detected by detecting the generation timing between specific pulses that occur in response to and comparing the amount of variation in the time difference between the generation timings over time.

[Example] Hereinafter, practical examples of the method for detecting an abnormality in a rotating body bearing of the present invention will be described based on the drawings.

Figure 's1 is a schematic diagram of a rotating body bearing abnormality detection device to which the rotating body bearing abnormality detection method of the present invention is applied.

Rotating body 1 such as this spindle, rotating roll or motor
has a rotating shaft 2. When the rotating shaft 2 is composed of a spindle or a rotating roll, it is supported by a pair of bearings 3 and rotated by a drive source (not shown). Further, when the rotating body 1 is constituted by a motor, a rotary encoder 5 is provided via a coupling 4 at one end of the six-rotary shaft 2 whose output shaft is supported by a bearing 31.

An abnormality detection circuit 6 that analyzes pulses is connected to the rotary encoder 5, and this abnormality detection circuit 6 uses the pulses generated from the rotary encoder 5 to detect the rotational position (angle) of the rotary shaft 2 and the rotation. Perform speed detection.

FIG. 2 shows an optical rotary encoder used in this invention.

The structure of the rotary encoder 5 includes a main body 51 and a rotating shaft 5.
2 is supported by a bearing 53 such as a ball bearing, and a rotating slit plate 54 is fixedly attached to this rotating shaft 52. A pattern is engraved on this rotating slit plate 54, and upon receiving light from a projecting light source 55 provided opposite to this rotating slit plate 54, light corresponding to the pattern is transmitted. Light source 55 for projecting light of this rotating slit plate 54
On the opposite side, a fixed slit plate 56 in which a multiphase array of slits 56a to 56Sac are bored is provided, and light receiving sensors 5a to 5C are arranged corresponding to the slits 56a to 56c. It is arranged.

The light transmitted through the rotating rotating slit plate 54 passes through the slits 58a to 56c of each phase of the fixed slit plate 56,
A pattern of light for each phase is sent to light receiving sensors 5a to 5c. As a result, a pulse train corresponding to each phase is output from the light receiving sensors 5a to 57c. Using this pulse train, the rotation angle and rotation speed of the rotary shaft 52 are detected, and the abnormality detection circuit 6 analyzes the pulse train of the rotary encoder 5 to detect irregularities in rotation and shaft runout of the rotary shaft 2. Aperiodic components can be separated and extracted.

Next, we will explain how to extract the aperiodic component of rotational shaft runout using this rotary encoder 5 in Figures 3 to '! J
This will be explained based on FIG.

Here, FIGS. 3 and 4 show the case where there is no runout of the rotating shaft, FIGS. Figure J8 shows a case where there is non-periodic vibration in the rotating shaft, and Figure 9 is an explanatory diagram illustrating the amount of variation in the time difference in generation timing between specific pulses of each phase during one measurement.

In FIG. 3, FIG. 5, and FIG. 7, the symbol C indicates the center of rotation of the rotary shaft 52 of the rotary encoder when there is no runout in the rotary shaft. On the other hand, the symbol in Figure 'M5 indicates the rotation center point when periodic vibration occurs in the rotating shaft 52 of the rotary encoder, and the symbol E in Figure 7 indicates the rotation center point when periodic vibration occurs in the rotating shaft 52 of the rotary encoder. It shows the center of rotation when

In this principle diagram, the rotary encoder has a three-phase output, and has a rotating slit plate 54 having slit patterns of two phases, B phase, and A phase from the inside of the rotation center. The light emitted from the projecting light source 55 is passed through the slit patterns for each phase, and is further passed through the slits 56a to 56c of the fixed slit plate 56, which are bored corresponding to each phase. This light is transmitted through light receiving sensors 5a to 5c corresponding to each phase.
The light receiving sensors 5a to 5c are located on the line CF.

'If there is no wobbling in the rotation axis as shown in Fig. The relationship naturally does not change, so there is no relative time change in the output pulses of each phase. Figure 4 shows the generation timing between specific pulses at a predetermined rotational position of the A phase and B phase at this time. Explain using. 'In the M4 diagram, from the rising edge (a) of a specific pulse of A phase, the corresponding B
Time required for rise (b) of specific pulse of phase T=T
n is always constant when there is no shaft runout on the rotating shaft.

Further, when there is periodic wobbling in the rotating shaft as shown in FIG. 5, the center of rotation moves periodically from point C to the point. Even in this case, the light receiving sensors 57a to 57c are connected to line C.
Since the light receiving sensors 57a to 57c are located on the line F, the slit patterns of each phase are detected at predetermined rotational positions that should be detected by the light receiving sensors 57a to 57c, that is, positions shifted from the line DG.

For example, in FIG. 5, the A-phase slit pattern is detected by an angle θ^, and the B-phase slit pattern is detected by an angle θB before reaching a predetermined rotational position both in terms of distance and time. become. In addition, at this time, the timing at which the A-phase light receiving sensor 5F C and the B-phase light receiving sensor 5B receive light from each slit pattern is relative to the angle θ.
This results in a shift of only the first line θB - θ8. That is, when there is periodic vibration in the rotation axis, the light receiving sensors 5a to 5
The relative positional relationship between the slit pattern of each phase and the slit pattern of each phase will fluctuate periodically compared to the case where there is no vibration, and the output pulse of each phase will also periodically fluctuate in relative time. .

At this time, the generation timing between the specific pulses of the A phase and B phase is different from that when there is no shaft runout on the rotating shaft. As shown in Figure J6, the time T required from the rising edge (C) of the A-phase specific pulse to the corresponding rising edge (d) of the B-phase specific pulse deviates by a time ΔT1 corresponding to the angle 01 minutes. .

That is, TseTn-ΔTl. However, since the shaft runout of this rotating shaft is periodic, no matter how many times it rotates, the CD-
It is constant, and ΔT1 is also always constant.

However, if there is non-periodic wobbling in the rotating shaft as shown in FIG. 7, the center of rotation moves from point C to point E non-periodically. Even in this case, the timing at which the A-phase light receiving sensor 57e and the B-phase light receiving sensor 5b receive light from their respective slit patterns is relative to the angle 02 minutes, as in the case where there is periodic vibration described above. It will be off by just that.

At this time, the generation timing between the A-phase and B-phase specific pulses corresponds to the rising edge (e) of the A-phase specific pulse, as shown in Figure 8, compared to the case where there is no shaft runout on the rotating shaft. The time T required for the rise (f) of the B-phase specific pulse deviates by a time ΔT2 corresponding to the angle 02 minutes.

That is, TmTn-ΔT2. However, since the shaft runout of this rotating shaft is non-periodic, the distance between CE and the direction of E as seen from C change each time it rotates, and 8T2 also changes each time. Accordingly, the time T will also vary. In this way, when the time T required for the specific pulse to rise for each rotation varies, the width of the variation in the time T corresponds to the aperiodic component of the shaft runout.

From the above, the magnitude relationship of the non-periodic component of the rotary shaft runout at the time of one measurement can be determined from the maximum and minimum values of the time difference in generation timing between specific pulses measured for each rotation.

This relationship will be explained based on FIG. 9. 'M9 In the figure, when a specific pulse of A phase rises (g), a corresponding specific pulse of B phase rises in the shortest time T-T■in (h), and the longest time T w T wax
If it rises at (i), find the difference x at T
Find wax −T win. This difference X indicates the non-periodic component of rotational shaft runout at a specific rotational position during one measurement.

Next, a method for detecting an abnormality in a bearing of a rotating body by casually comparing the amount of variation in the time difference between the generation timings of such specific pulses will be explained using a $10 diagram.

In FIG. 10, (1) indicates the rise ( j), (2) shows the rise of a specific pulse of the B phase corresponding to this specific pulse of the A phase, which is one measurement in the 5-phase state, and rises in the shortest time T-To■in. The case (k) and the case (It) where the signal rises in the longest time T-To*aX are shown. Here, xOmTOmax-TOmin indicates a non-periodic component of rotational shaft runout at a specific rotational position in the initial state.

When the non-periodic component of the rotary shaft runout changes when the rotating body 1 is put into use, the allowable range is determined by the decrement from the shortest rise time (k) of a specific pulse of the B phase in the initial state by a, If the increment from the longest rise time (Jt) is also a, then the shortest rise time as an allowable range is (
TOgiin -a), the longest rise time is (TOm
ax+a).

That is, after the rotating body 1 is used, the rising edge of the specific pulse indicating the non-periodic component is (To, 4n-a)≦T≦(T
Osax+a), it is determined that it is within the allowable range, and when it is outside this range, it is determined that an abnormality has occurred in the bearing 3.

This will be explained using (3), (4), and (5) in FIG. (3), (4), and (5) all indicate the rise range of a specific B-phase pulse during one measurement after the start of use.

When measuring (3), the shortest rise (m) and longest rise (n) of the B-phase specific pulse are within the allowable range (
TOmin-a)≦T≦(T Off1ax+a). However, in the case of measurement (4), the longest rise time (p) is within the allowable range, but the shortest time rise (0) is outside the allowable range. In addition, in the case of measurement (5), the shortest time rise (q) is within the allowable range, but the longest time rise (r) exceeds the allowable range. In this way, it is determined that the non-periodic component of the shaft runout exceeds the permissible range. This determines that an abnormality has occurred in the bearing of the rotating body.

In this embodiment, the 2-phase, B-phase, and A-phase pulses of the rotary encoder are outputted from a set of light receiving sensors 57a to 57c corresponding to each phase to evaluate the non-periodic component of the rotation shaft runout. However, this can also be done using two sets of light receiving sensors, in which case the aperiodic component can be determined with higher accuracy.

FIG. 11 shows a principle diagram showing the principle of the evaluation method for rotary encoder rotation axis runout when two sets of light receiving sensors are used. In FIG. 11, one set of light receiving sensors 57a to 5
7c is on the line CF as in the above case, and the other set of light receiving sensors 58a to 58c are on the line CI intersecting with the line CF. Another set of light receiving sensors 58
A to 58C also output pulse trains of each phase corresponding to 2-phase, B-phase, and human phase, respectively.

As shown in FIG. 11, when the rotating shaft 2 has a non-periodic runout and the center of rotation of the rotating shaft 2 moves to E, the light receiving sensors 57a to 57c are on the line CF, and the light receiving sensor 58 is on the line CF.
Since a to 58c are on the line CI, the predetermined rotational position that each light receiving sensor should originally detect is on the line EH for the light receiving sensors 57a to 57c, and on the line EJ for the light receiving sensors 58a to 58c. The slit pattern of each phase is detected at a position shifted from the top. Note that the movement of the center of rotation from C to E is actually minute, so even if the center of rotation moves to point E, each of the light receiving sensors 7a to 7c,
8a to 8c detect each phase slit pattern.

Therefore, as described above, the light receiving sensors 57b and 57c rotate the A-phase slit pattern and the B-phase slit pattern by an angle θ^ and an angle 06, respectively, before reaching a predetermined rotational position both in terms of distance and time. Furthermore, the timing of detecting the slit pattern of each phase and receiving the light is relatively shifted by an angle θ2 exposure θB−θ^.

Therefore, the generation timing between the A-phase and B-phase specific pulses is shifted by a time ΔT2 corresponding to the angle 02 minutes.

Similarly, the light receiving sensors 58b and 58c detect the A-phase slit pattern and the B-phase slit pattern by an angle θ^l and an angle θBl, respectively, with a delay from the predetermined rotational position in terms of distance and time. become,
The timing of receiving light from the slit patterns of each phase is also relatively shifted by an angle θ3=θBl−θ^1. Furthermore, the generation timing between the A-phase and B-phase specific pulses is also shifted by a time ΔT3 corresponding to the angle 03 minutes.

In this way, when the generation timing between the specific pulses of the A phase and B phase is measured separately using two sets of light receiving sensors, the time difference in the generation timing ΔT2. From ΔT3, the above angle θ2. θ3 can be found. Therefore, the direction of axial runout of the rotating shaft 2 can be specified, and the non-periodic component can be measured and calculated with high precision even for two-dimensional axial runout.

[Effects of the Invention] As described above, the present invention uses a rotary encoder having a multiphase output that is attached to rotate in synchronization with the rotating shaft of a rotating body supported by a bearing, and the rotation of this rotary encoder is An abnormality in the bearing of the rotating body is detected by comparing over time the amount of variation in the time difference in the generation timing between specific pulses of each phase generated corresponding to a predetermined rotational position of the shaft. Here, the pulses to be detected need only be pulses whose relative positional fluctuations can be grasped, so a highly accurate rotary encoder is not required.

Therefore, even if an inexpensive device is used, abnormality or deterioration of the bearing can be detected easily and with high sensitivity.

[Brief explanation of the drawing]

'M1 is a schematic diagram of a rotating body bearing abnormality detection device to which the rotating body bearing abnormality detection method of the present invention is applied.'! Figure J2 is a structural diagram of the optical rotary encoder used in this invention, Figures 3, 5, and 7 are principle diagrams showing the principle of rotation axis runout of this rotary encoder, Figures 4, 1J6
Figure 8 and Figure 8 are explanatory diagrams explaining the generation timing between specific pulses of each phase, Figure 9 is an explanatory diagram explaining the amount of variation in the time difference in the generation timing between specific pulses, and Figure 1J10 is an explanatory diagram explaining the generation timing between specific pulses. An explanatory diagram illustrating a method for detecting bearing abnormalities by comparing timing over time. Figure 11 is a principle diagram illustrating the principle of a method for measuring rotational shaft runout of a rotary encoder when two sets of light receiving sensors are used. be. In the figure, 1 is a rotating body, 2 is a rotating shaft, 3 is a rotary bearing, 4 is a coupling, 5 is a rotary encoder, 6 is an abnormality detection circuit, 54 is a rotating slit plate, 55 is a light source for projection, 56
is a fixed slit plate, and 57a to 57c are light receiving sensors. Figure 1 Figure 2 Figure 4 Figure 5 Figure 6 Figure 7! Figure 8 Figure 9 Figure 10

Claims (1)

[Claims] Pulses of each phase are generated by the rotation of a rotary encoder having a multiphase output, which is attached to rotate in synchronization with the rotating shaft of a rotating body supported by a bearing. By detecting the generation timing between specific pulses of each phase that occur corresponding to a predetermined rotational position of the rotation axis for each rotation, and comparing the amount of variation in the time difference of this generation timing over time, the rotation A method for detecting an abnormality in a bearing of a rotating body, the method comprising detecting an abnormality in a bearing of a rotating body.