JPH0523697B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a small-sized vibration meter for detecting vibrations of a structure as an electrical signal and measuring the level of vibrations.

[Conventional technology]

Vibrations that occur during the operation of mechanical structures such as electric motors are caused not only by unbalanced conditions due to processing errors and assembly errors of the rotating body itself, but also due to mechanical and electrical aging of the constituent parts, such as between parts. Measuring the vibration level of a structure is useful for monitoring structural abnormalities because it shows an appropriate response to cracks that occur or gaps that occur due to drying of the insulating layer in the motor winding groove. considered essential.

Conventionally, the vibration level of mechanical vibrations has generally been measured by electrically detecting the speed and acceleration of vibrations, and inputting the detected electrical quantity into a vibration meter that indicates the magnitude of vibrations. In large-scale plants in industrial fields such as electric power, steel, and chemicals that use many rotating machines, the condition of machines through vibration is actively monitored in order to improve plant availability and effectively carry out maintenance and repairs. Normally, lifeguards patrol regularly and measure vibrations. However, (1) Since vibration sensors are attached and measured each time, the vibration measurement position and sensor installation method are not necessarily constant, resulting in individual differences.

(2) Since the vibration sensor and the vibration meter body are separated, measurement requires labor and time.

(3) Most of the objects to be measured are rotating machines, and sensor installation and vibration measurement are done while the machine is in operation, which can be dangerous and sometimes make measurement impossible.

(4) Specialized skills and experience are required to operate the vibration meter.

There are problems such as. For this reason, for highly important machines, there is a tendency to use a centralized monitoring method in which only the vibration meter sensor is fixed to the part of the machine to be measured, and the vibration level is centrally measured from a distance to monitor machine abnormalities. However, if you want to measure right next to the machine,
Since the machine is only equipped with a sensor, a separate vibration meter is required. For this reason, the same applicant devised a compact vibration meter in which all the circuits and power supply necessary for measuring and displaying vibration levels, from the vibration sensor to the vibration level display circuit, were integrated into the case. Efforts are being made to resolve the problem (Patent Application No. 1986-205581). Furthermore, in order to make it easier to read the displayed vibration level, an improved compact vibrator has been proposed in which only the display device is removable from the case and can be moved to multiple predetermined positions on the case.

[Problem that the invention seeks to solve]

As described above, the following are the problems when trying to use a small vibration meter that can take measurements close to the machine for centralized monitoring instead of conventional sensors.

First, the same applicant devised a compact vibration meter having an external output function for outputting an electrical signal at a level proportional to the vibration level of the machine (Japanese Patent Application No. 1983-022255). However, when performing centralized monitoring using this vibration meter, the external output of each vibration meter attached to each machine must be constantly monitored, just as in the case of conventional centralized monitoring in which only the vibration sensor is attached to the part to be measured. It turns out. For this reason,
As before, equipment. Huge costs such as wiring work will be required.

On the other hand, in large plants with many machines,
Vibration monitoring for most machines is done through alarm management. This alarm management uses an alarm to determine whether or not the machine is being operated within the vibration level set for each machine.To make this determination possible, it has a vibration level determination function. A compact vibration meter has been proposed that generates an alarm by flashing a light emitting diode when a preset level is exceeded (Japanese Patent Application No. 187211/1982).
If such a subtotal vibration meter is used for centralized monitoring,
Although huge costs for equipment and wiring work are no longer necessary, since the flashing light emitting diodes are visually observed from a distance, it may be difficult to clearly identify the machine that is causing abnormal vibrations.

Therefore, a small vibration meter that can read the vibration level near the machine and transmits only the presence or absence of machine abnormalities from a distance to a central monitoring position at low cost via infrared light emitted by near-infrared light emitting diodes was filed in the same application. It was devised by a person (patent application 1986-
No. 265282). However, since this small vibration meter does not have a vibration level memory function, it is not possible to know the state of the machine before the abnormality occurs, and there is a problem that it cannot provide the necessary information for repairing the machine or taking measures to prevent recurrence of the abnormality. be.

The purpose of this invention is to have a function that can be installed in advance on a structural part to be monitored, so that the vibration level can be read near the structure, and the presence or absence of abnormal vibration of the machine can be transmitted to a central monitoring position at low cost. To provide a small vibrating device which has a function of not only vibration but also storing previous vibration history and recalling the stored contents as needed.

[Means for solving problems]

In order to achieve the above object, according to the present invention,
A small vibration meter is housed in a common case, and includes a vibration sensor that detects the vibration of a structure as an electrical signal, an amplification circuit that amplifies the detected electrical signal, and an integration circuit that integrates the amplified electrical signal. , a detection circuit that detects the integrated electrical signal; an analog-to-digital conversion circuit that converts the analog electrical signal output from the detection circuit into a digital electrical signal; A vibration level that calculates the vibration level of a structure using an electric signal, drives a display circuit that displays the calculated vibration level externally, and a storage circuit that stores the vibration level, and sets the vibration level in advance. a microcomputer to be compared with, the display circuit, and the memory circuit;
The device is also provided with a power source for operating each of the circuits.

[Effect]

By structuring the compact vibration meter as described above, it is possible to read the vibration level near the structure, and it can be equipped with the function of inexpensively transmitting the presence or absence of abnormal vibration of the machine to a central monitoring position. Since it becomes possible to store vibration levels stored in the storage circuit at predetermined time intervals, when abnormal vibration occurs, the storage operation in the storage circuit is automatically stopped, and the vibration level that has already been stored can be stored in the storage circuit. By calling the information in chronological order, it is possible to know the history of the vibration level leading up to the abnormal vibration and the correlation between this history and the operating conditions, and it is possible to more accurately and easily prevent recurrence of the abnormality.

〔Example〕

Fig. 1 shows an example of the circuit configuration of a small vibration meter based on the present invention, and Figs. 3, 4, 5, and 6 show the flow of a job performed by the circuit configuration of Fig. 1. . Here, Figures 3 to 5 are 1
The two flowcharts are divided and shown due to the paper size, and FIG. 6 shows the connection relationship of these diagrams.

In FIG. 1, 1 is a vibration sensor for detecting the vibration of a mechanical structure as an electrical signal,
A piezoelectric vibrating element that detects the acceleration of vibration is used to convert mechanical vibration into an electrical signal. An electrical signal proportional to vibration acceleration detected by this vibration sensor 1 is amplified in an amplifier circuit 2. This amplified electrical signal will be integrated twice by integrating circuits 3 and 4. Vibration levels representative of the range of vibration levels classified according to degree are set using vibration speed and vibration displacement.

(2) Vibration acceleration is used to evaluate the strength of machines and the impact on the human body.

For these reasons, the number of integrations of the input electrical signal is determined depending on which vibration level of the three types of vibration, acceleration, velocity, and displacement, is to be measured.
Depending on the number of times, both integration circuits 3 and 4 may be short-circuited, or integration circuit 4 may be short-circuited. Now, the acceleration of the vibration is x¨, the velocity is x〓,
If the displacement is x, the maximum displacement of vibration is A, the angular velocity is ω, and the time is t, then the relationship between the magnitude and phase of the signal in each circuit is as follows: For amplifier circuit 2, x¨=Aω ² sinωt For integration circuit 3, x〓 =∫x〓dt=-Aωcosωt In the integrating circuit 4, it is expressed as x=∫x〓dt=-Asinωt.

Since the output signals from amplifier circuit 2 and integration circuits 3 and 4 are all AC signals with angular velocity ω,
A detection circuit 6 to which an amplifier circuit 5 is added converts the signal into a DC signal. This converted DC analog signal is processed by an analog-to-digital conversion circuit (hereinafter referred to as A/D).
The signal is input to a converter circuit (hereinafter referred to as "microcomputer") 7, where it is converted into an 8-bit digital signal, and which is input to a microcomputer (hereinafter referred to as "microcomputer") 8. The microcomputer 8 of this example performs jobs as shown in FIGS. 3 to 5. To explain Fig. 1 according to this job flow, (1) Set the arithmetic and control unit (hereinafter referred to as CPU) control switch 18 of the microcomputer 8 to the measurement mode "manual".
(Step S1 in FIG. 3, hereinafter simply referred to as S1. The same applies to other steps.) (1-1) Turn on the analog circuit power switch 17 (S5) and turn on the digital display circuit 10. Display “READY” for 5 seconds to stabilize analog circuit operation.

(1-2) Next, start and stop sampling so that the analog data is sampled at 0.2 second intervals.
An instruction is given to the D conversion circuit 7 (S7). The average value of the digital data inputted from the A/D conversion circuit 7 for 10 samplings is determined (S8, S9), and this is determined as the average vibration level for 2 seconds (S10).

(1-3) In order to display the average vibration level for these two seconds each time, the digital display circuit 10 having a display section using a liquid crystal or a light emitting diode is driven. Furthermore, when an alarm signal (described later) is generated (S16), the display notifies the outside of the presence or absence of an alarm by repeatedly blinking (flicker function). Therefore, the measurer can determine the abnormality of the machine on the spot.

(1-4) After performing this operation for one minute (S12), turn off the analog circuit power switch 17 to stop the measurement. By doing so, consumption of the power source 14 can be prevented. Moreover, the measurer only has to measure the vibration level of the structure within a one-minute motion range.

(2) When the CPU control switch 18 of the microcomputer 8 is set to the measurement mode "auto" (S2), (2-1) at the time interval measured by the CPU control switch 19 (for example, 1, 2, 3... start the measurement operation (S3).

(2-2) When the specified time comes and the measurement starts,
Determine whether there is an alarm (described later) (S16),
If an alarm has occurred in the past, no measurement is performed, but if there is no alarm, repeat steps (1-1) to (1-3) 15 times to find the average vibration level for 30 seconds (S14). .

(2-3) Next, compare the alarm level established in advance with the CPU control switches 17 and 18 with the average vibration level for 30 seconds, and if the vibration level is below the alarm level, the vibration level is stored in the memory circuit 9. The time and time at the time of the change are stored as data (S18). In this example, the amount of stored data is 30, and when it exceeds 30, the oldest data is automatically deleted and new data is added.

Note that the setting of the alarm level is determined by the VDI and ISO evaluation standard levels as described above. After storing the data in the memory circuit 9, the analog circuit power switch 17 is turned off (S19) and the process waits until the next designated time comes.

(2-4) If the average vibration level for 30 seconds exceeds the alarm level (S16), the microcomputer 8 memorizes that an alarm has occurred (S17), and at the same time instructs the digital display circuit 10 to flicker or oscillates. The circuit 11 is driven to output a constant rectangular wave signal, which causes the amplification circuit 12 to turn on and off repeatedly, and the near-infrared diode 13
blinks repeatedly and emits near-infrared rays into the air. Furthermore, by storing the alarm in the microcomputer 8, the microcomputer 8 controls the storage circuit 9 to stop the next data store operation.

(3) Specify the CPU control switch 18 of the microcomputer 8 to the measurement mode "memory recall" (S20),
Each time the CPU control switch 19 is turned on (S21), the data stored in the memory circuit 9 is recalled (S22), and past vibration level changes can be known. Therefore, by activating this data storage function, the interval of periodic checks of the vibration level that have been conventionally performed can be lengthened or shortened to improve the accuracy of the checks. This interval can be adjusted arbitrarily by changing the measurement time interval described in (2-1).

On the other hand, Fig. 2 shows an example of a receiving circuit that receives near-infrared rays emitted by this vibrometer and converts them into electrical signals. The signal is received by the phototransistor 15 and output as an electrical signal indicated by an arrow. This output is sent to a central monitoring room (not shown), where it lights up a lamp or sounds a buzzer. In the central monitoring room, it is possible to know through lamps and buzzers that the vibration level of the machine has reached an abnormal value, but it is not possible to know the history of the vibration level or the operating conditions under which it occurred. However, with this vibration meter, (2-1)
As mentioned above, since data rewriting is stopped at the same time as an alarm occurs, past data is retained, and by recalling that data, it is possible to analyze the data in detail. In addition, the memory circuit 9
The stored data can be erased using CPU control switches 18 and 19, and measurement can be started again.

〔Effect of the invention〕

As described above, according to the present invention, a small vibration meter that measures the vibration of a mechanical structure is housed in a common case, and a vibration sensor that detects the vibration of the structure as an electrical signal; a circuit that amplifies a signal; a circuit that integrates the amplified electrical signal; a circuit that detects the integrated electrical signal;
a circuit that converts an analog electrical signal output from the detection circuit into a digital electrical signal; a circuit that calculates a vibration level of the structure using the digital electrical signal while controlling the analog-to-digital conversion circuit; Drives a display circuit for external display and a storage circuit for storing the vibration level, and when the calculated vibration level is below a predetermined level, displays only the calculated level on the display circuit and stores it in the storage circuit. a microcomputer that displays the level with an alarm when the calculated vibration level exceeds a predetermined level and stops the storage operation of the storage circuit; the display circuit; the storage circuit; and each of the above. (1) This compact vibration meter can be attached to the monitored part of the structure in advance, and the vibration level can be read near the structure. The input signal to the central monitoring system for centrally monitoring multiple structures from a distance was generated via an oscillation circuit driven by a microcomputer in the vibration meter. For example, it is possible to transmit an alarm signal using near-infrared rays as a signal transmission medium to a centralized monitoring system, and it is possible to create a centralized monitoring system using small vibration meters without requiring huge costs such as equipment and wiring work. It becomes possible.

(2) The vibration level is automatically memorized at the specified time interval, and the memorized vibration level can be read on the display section of the vibration meter. If the vibration level is below a preset level, the cycle of patrol work can be extended to save labor, and if it is close to the set level, subsequent changes in the vibration level are carefully monitored at appropriate intervals. The quality of monitoring work can be improved without wasting time.

(3) If the vibration level of the machine exceeds a preset level, an alarm will be generated and data storage will stop; therefore, the previous data stored at specified time intervals will be sequentially recalled to the display circuit. By reading the information, it is possible to know the time history of the vibration level leading up to the abnormal vibration and the correlation between this time history and the operating conditions at that time, making it possible to more accurately and easily prevent the recurrence of abnormalities. I can do it. Further, future maintenance and operation guidelines can be formulated more accurately.

(4) By installing and using this vibration meter even in monitored areas that cannot be approached due to danger during operation or where wiring is difficult, abnormalities can be detected by reading the stored data when the machine is stopped. The presence or absence of vibration can be evaluated.

[Brief explanation of the drawing]

FIG. 1 is a circuit configuration diagram of a small vibration meter according to an embodiment of the present invention, and FIG. 2 is a circuit configuration diagram of a receiver that receives near-infrared rays as an alarm signal emitted from the small vibration meter and converts it into an electrical signal. Figures 3, 4 and 5 are partial diagrams showing the flow of jobs performed by the microcomputer in Figure 1, respectively, and Figure 6 is an overall diagram showing the connection relationships in Figures 3 to 5. It is a diagram. DESCRIPTION OF SYMBOLS 1...Vibration sensor, 2...Amplification circuit, 3...Integrator circuit, 4...Integrator circuit, 6...Detection circuit, 7...
...A/D conversion circuit, 8...Microcomputer, 9...Storage circuit, 10...Display circuit, 14...
…power supply.

Claims (1)

[Claims] 1. A device for measuring the vibration level of a structure, which includes a vibration sensor that detects the vibration of the structure as an electrical signal, and an amplifier that amplifies the detected electrical signal, in a common case. a circuit, an integrating circuit that integrates the amplified electrical signal, a detection circuit that detects the integrated electrical signal, and an analog-to-digital conversion that converts the analog electrical signal output from the detection circuit into a digital electrical signal. a circuit, a display circuit that calculates the vibration level of the structure using the digital electric signal while controlling the analog-to-digital conversion circuit and displays the calculated vibration level externally, and a memory that stores the vibration level. A microcomputer that drives a circuit and compares the vibration level with a preset vibration level, the display circuit, the memory circuit, and a power source that operates each of the circuits. Total. 2. In the small vibration meter according to claim 1, when the display circuit and the memory circuit are driven by the microcomputer, when the calculated vibration level is below a predetermined level, only the calculated level is displayed. The vibration level is also stored, and when the calculated vibration level exceeds a predetermined level, a warning is displayed and the storage operation of the storage circuit is stopped. Total. 3. In the small vibrator according to claim 1, the display circuit and memory circuit driven by a microcomputer are coupled so that the vibration levels stored in the memory circuit can be sequentially recalled to the display circuit. A small vibration meter characterized by: