JPH052251B2 - - 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 mechanical structures such as electric motors as electrical signals 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 the electric power, steel, and chemical industries that use a large number of rotating machines, the condition of machines using vibrations 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 vibration meter 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 (patent application). Showa 60-
No. 289736).

In addition, in order to repurpose this small vibration meter for intensive monitoring, the same applicant has proposed a small vibration meter that has the function of outputting an electrical signal proportional to the vibration level of the structure to the outside (particularly Gansho 61-022255
issue).

Furthermore, in large plants with many machines, the purpose of normal operation monitoring would be to be able to determine whether or not each machine is operating at a vibration level set for each machine, rather than the measured vibration level itself. To achieve this, it has a comparison function with the set level, and blinks a light emitting diode when the measured level exceeds the set level;
The same applicant has proposed a small-sized vibration meter that uses this flashing as an alarm (Japanese Patent Application No. 1872-11-1982).

[Problem that the invention seeks to solve]

The problems to be solved when using the above-mentioned conventional small-sized vibration meter for centralized monitoring of a large number of mechanical structures are as follows. In other words, there are devices in which a display device that displays the vibration level is removable from the case (Japanese Patent Application No. 60-289736), and devices that have the function of outputting an electrical signal proportional to the vibration level to the outside (Japanese Patent Application No. 61-1989). 022255), the external output of each vibration meter attached to each mechanical structure must be constantly monitored, which requires enormous costs for wiring work. In addition, when the measured vibration level exceeds a set value, a light emitting diode blinks, and this blinking is used as an alarm (patent application 187211/1987), in which the mechanical structure is designed to visually confirm the alarm. It is difficult to monitor when a large number of objects are present, and therefore it is difficult to quickly discover abnormalities in the machine.

The purpose of this invention is to install it in advance at the part of the structure to be monitored, so that it is possible to read the vibration level near the structure, and to easily check whether or not there is an abnormality in the structure from a distance, without spending a huge amount of money. It is an object of the present invention to provide a small-sized vibration meter that can be centrally monitored without inviting people.

[Means for solving problems]

In order to achieve the above object, according to the present invention, a small vibration meter includes a vibration sensor that detects vibrations of a structure as an electrical signal, and a circuit that amplifies the detected electrical signal, in a common case. , a circuit that integrates the amplified electrical signal, a circuit that detects the integrated electrical signal, a circuit that converts the analog electrical signal output from the detection circuit into a digital electrical signal, and this analog-to-digital conversion. While controlling the circuit, the digital electric signal is used to calculate the vibration level of the structure, drive a display circuit that displays the vibration level externally, and compare the vibration level with a preset vibration level to determine the vibration level. A microcomputer that drives a lighting circuit for a near-infrared light emitting diode when a set level is exceeded, the display circuit and lighting circuit driven by the microcomputer, and a power source that operates each of the circuits. do.

[Effect]

In this way, when the measured vibration level exceeds a preset vibration level, near-infrared light emitting diodes are activated, and near-infrared light is used as an alarm signal, which can be used to monitor signals from individual structures to centralized monitoring locations. It does not require huge costs such as wiring work, and the frequency of the blinking near-infrared rays is different for each structure, and the frequency of the alarm signal that is converted to an electrical signal at the receiving position of the near-infrared rays is changed for each structure. Therefore, a circuit that separates frequencies can be used to accurately identify a structure in which an abnormality has occurred, and each of the different frequencies can be used to identify, for example, the applicable power source used for lighting the environment in which the structure is installed. By setting the frequency to twice the frequency, that is, to a frequency different from the light/dark frequency of a mercury lamp or fluorescent lamp, intensive monitoring with less influence from external light etc. is possible. The reason why a near-infrared light emitting diode is used is that its emission spectrum is in the infrared region, its life is long, and its response speed is fast.

〔Example〕

FIG. 1 shows an embodiment of the circuit configuration of a vibration meter based on the present invention. In the figure, reference numeral 1 denotes a vibration sensor for detecting the vibration of a mechanical structure as an electric signal, and a piezoelectric vibrating element that detects the acceleration of vibration is used to convert the mechanical vibration into an electric 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 is transmitted to integrating circuits 3 and 4.
(1) Each of the standard levels standardized by international standards such as VDI and ISO and used to evaluate mechanical vibrations, that is, the range of vibration levels classified according to the degree of danger, is integrated twice. The representative vibration levels 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 is measured among the three types of vibrations: acceleration, velocity, and displacement. 4 may be shorted together, or the integrating circuit 4 may be shorted. Now, if the acceleration of vibration is x..., the speed is x・, the displacement is x, the maximum displacement of vibration is A, the angular velocity is ω, and the time is t, the relationship between the magnitude and phase of the signal in each circuit is as follows: Phase width In circuit 2, x‥=Aω ² sinωt, in integrator circuit 3, x・=∫x‥dt=−Aωcosωt, and in component circuit 4, 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 (1) instructs the A/D conversion circuit to start and stop sampling so as to sample data at 0.2 second intervals;

(2) Sampling input from the A/D conversion circuit
The average value of the 10 data is determined as the average vibration level for 2 seconds.

(3) In order to display the average vibration level for these two seconds each time, the display circuit 9 having a display section using a liquid crystal or a light emitting diode is driven.

(4) At the same time as this display circuit 9 is driven, the two-second average vibration level is compared with a vibration alarm value preset in the microcomputer's memory each time. When the vibration level exceeds the alarm value, the oscillation circuit 10 is driven to blink the near-infrared light emitting diode at a constant frequency. Note that the level of the alarm value set in the microcomputer 8 is determined by the VDI and
Determined by ISO evaluation standard level.

When the vibration level exceeds the alarm value set in the memory of the microcomputer 8 and the oscillation circuit 10 is driven by the microcomputer 8, the oscillation circuit 10 outputs a rectangular wave signal with a constant frequency (80Hz in this example). ,
At that frequency, the transistor 12 turns on and off, the near-infrared light emitting diode 11 repeatedly blinks, and near-infrared light is emitted into the sky. Therefore, the oscillation circuit 10 constitutes a lighting circuit for the near-infrared light emitting diode 11. The power source 13 is an operating power source for the small vibration meter, and the positive electrode indicated by * and the negative electrode indicated by ** are connected to terminals with the same symbol of the respective circuits.

FIG. 2 shows an example of a receiving circuit that receives near-infrared rays emitted by the small vibrometer of the present invention and converts them into electrical signals. A light beam from a near-infrared light emitting diode 11 that repeatedly blinks at a constant frequency is received by a phototransistor 14 in a receiving circuit through the air, and then passed through a resistor 1.
An electrical signal is output from both terminals of 6 as shown by the arrow. The frequency of this electrical signal matches the blinking frequency of the near-infrared light emitting diode, and if this frequency is 80Hz as in this example, it is used for lighting the environment where the receiving circuit is placed. In cases where the frequency of light and darkness is twice the commercial power supply frequency, such as in mercury lamps and fluorescent lamps, and because the frequency is different compared to direct current light such as sunlight, the output side of the receiving circuit (Figure 2) is 80 Hz. By providing a circuit that separates and extracts the light, the blinking frequency of the near-infrared light emitting diode can be reduced.
It is possible to accurately identify structures to which a small vibration meter with a frequency of 80Hz is attached.

FIG. 3 shows an external perspective view of an embodiment of a small vibrometer constructed according to the present invention. A display board is provided on the top of the box-shaped vibration meter to digitally display the vibration level measured by the vibration meter, and is configured so that the vibration level can be read near the structure. ing. The vibration meter 21 configured in this way is attached to rotating machines 23 to 25, which are mechanical structures, as shown in FIG. 4, for example, and when the vibration of the rotating machine exceeds a preset vibration level, Near-infrared rays emitted from the vibrometer are received by the receiver 22 and converted into electrical signals. This electrical signal is transmitted to the central monitoring system 30, which distinguishes the frequency of the electrical signal and lights up a lamp corresponding to the rotating machine in which the abnormality is occurring or operates a buzzer to notify a supervisor of the abnormality. Here, the receiver 22 is installed in a range where the small vibration meter 21 can be seen directly, and a plurality of rotating machines within this range are monitored via one receiver. In this case, the frequency of the blinking of the near-infrared light emitting diode emitted by each small vibration meter is set to be a different frequency for each vibration meter, and a circuit for discriminating this frequency is provided in the central monitoring system 30.

Large plants have many machines to monitor, and on the other hand, the number of machines that can be directly viewed with just one receiver is limited, so it is difficult to monitor all machines through one receiver. Because I can't
The machine is divided into blocks, one receiver is installed in each block, and the frequency of near-infrared rays emitted by each small vibration meter in the same block is the same, so that the centralized monitoring system 30 detects abnormalities in each block. When an abnormality alarm is detected, the supervisor patrols only the machines belonging to that block, and by checking the vibration level displayed on the vibration meter of each machine, the machine that is causing the abnormality can be easily discovered. I can do it. Of course, it is also possible to set the near-infrared rays emitted by the small vibration meters belonging to each block to different frequencies, input all frequencies to the central monitoring system, and directly identify the machine causing the abnormality using the discrimination circuit. It's not impossible. However, if you monitor each block as described above, there is a limit to the range of frequencies that can be used, and even when the number of machines to be monitored is tens to hundreds, there will be no problem. This has the advantage that abnormality monitoring can be performed without difficulty.

〔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 electric signal, and a vibration sensor that detects the vibration of the structure as an electric signal. A circuit that amplifies an electrical signal, a circuit that integrates the amplified electrical signal, a circuit that detects the integrated electrical signal, and a circuit that converts the analog electrical signal output from the detection circuit into a digital electrical signal. Then, while controlling this analog-digital conversion circuit, the vibration level of the structure is calculated using the digital electric signal, and a display circuit that displays the vibration level externally is driven, and the vibration level is set in advance. If the vibration level exceeds the set level, the microcomputer that drives the near-infrared light emitting diode lighting circuit, the display circuit and lighting circuit driven by this microcomputer, and the respective circuits described above are operated. This compact vibration meter can be installed in advance at the monitored part of a structure and the vibration level can be read near the structure.
When multiple structures are centrally monitored from a distance, the input to the central monitoring system is an alarm signal that indicates only the presence or absence of an abnormality determined inside the vibration meter, and this alarm signal is transmitted to a nearby system with a long life and a fast response speed. As near-infrared light emitted by an infrared light emitting diode, the blinking frequency of this diode can be set for each vibration meter to a frequency that is different from the frequency of external light such as mercury lamps, fluorescent lights, sunlight, etc. to reduce the effects of disturbance. (1) The alarm signal is transmitted through the air, eliminating the need for complicated wiring work around the structure and eliminating the huge expense required for signal transmission.

(2) By providing a circuit that discriminates signal frequencies within the centralized monitoring system, it is possible to accurately and easily identify structures that are experiencing abnormalities.

(3) Since multiple near-infrared rays emitted as alarm signals can be received by one receiving circuit, multiple structures can be monitored even if the number of structures being intensively monitored is tens to hundreds. Group monitoring is possible by dividing the structure into individual blocks and monitoring each block as one structure.If a block containing an abnormal structure is found, the vibration level can be easily read while visiting that block. This makes it possible to efficiently monitor a large number of structures, and it is easy to use either individual monitoring or group monitoring depending on the number of structures to be monitored.

[Brief explanation of the drawing]

Fig. 1 is a circuit configuration diagram of a small-sized vibrometer according to an embodiment of the present invention, and Fig. 2 shows a circuit configuration of a receiver that receives near-infrared rays as an alarm signal emitted from the small-sized vibrometer and converts them into electrical signals. Receiving circuit, FIG. 3 is an external perspective view of a small vibration meter according to an embodiment of the present invention, and FIG. 4 shows a method of intensive monitoring when multiple structures are intensively monitored using the small vibration meter of the present invention. It is an explanatory diagram. 1... Vibration sensor, 2... Integrating circuit, 3, 4... Integrating circuit, 5... Amplifying circuit, 6... Detecting circuit, 7... A/D
Conversion circuit, 8... Microcomputer, 9... Display circuit, 10... Oscillation circuit (lighting circuit), 11... Near-infrared light emitting diode, 13... Power source, 21... Small vibration meter, 23, 24, 25... Structure.

Claims (1)

[Claims] 1 A device for measuring the vibration level of a structure, which includes, in a common case, a vibration sensor that detects the vibration of the structure as an electrical signal, a circuit that amplifies the detected electrical signal, and a circuit that amplifies the detected electrical signal. A circuit that integrates an 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, and a circuit that controls the analog-to-digital conversion circuit. Calculates the vibration level of the structure using the digital electric signal, drives a display circuit that displays the vibration level externally, and compares the vibration level with a preset vibration level to determine whether the vibration level exceeds the set level. The case is a compact device characterized by comprising a microcomputer that drives a lighting circuit for a near-infrared light emitting diode, the display circuit and lighting circuit driven by the microcomputer, and a power source that operates each of the circuits. Vibration meter.