JPS6255085B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a waveform level determination device.

FIG. 1 and FIG. 2 are block diagrams showing two types of conventional waveform level determination devices, and FIG. 3 is a waveform diagram for explaining FIGS. 1 and 2. 1 in Figure 1 is a comparator, and the reference level R shown in Figure 3a is
is compared with the input waveform W, and at the portion where the input waveform W exceeds the reference level R, a pulse is generated as shown in FIG. 3b. 2 is a counter that counts the number of input pulses. 3 is a discriminator, when more than a certain number of pulses are counted within a certain time,
This is to determine whether the source of the input waveform W is in a predetermined or higher state. For example, if the input waveform (in a press punching operation) is the sound from the press, if a certain number of pulses or more are counted, this indicates that the press mold has been damaged or its wear has progressed. In Figure 2, 1 is a comparator, 3 is a discriminator,
4 is an integrator which integrates each pulse shown in FIG. 3b and derives the sum of the integrated values at fixed time intervals. Similarly to FIG. 1, when the integrated value from the integrator 4 exceeds a certain value, the discriminator 3 judges that the waveform generation source is in a state exceeding a predetermined value, for example, is abnormal.

The configuration and operation of the conventional waveform level determination device are as described above, but in the case of the waveform generation source shown in FIG. There will be a need to increase the amount. Furthermore, in this case, it is not possible to take a long certain period of time (judgment time). Furthermore, in the case of Figure 2, the input to the integrator 4 differs depending on the frequency component, making it difficult to set the operating reference value, and since the pulse frequency is large, the integrator itself must be of high quality. .

The present invention aims to eliminate the above-mentioned drawbacks and provide a waveform level determination device that requires fewer bits and requires a longer determination time.

FIG. 4 is a block diagram showing an embodiment of the waveform level determination device of the present invention. 1 to 3 in the figure are the first
It is the same as the figure, and the explanation will be omitted. 5 is a monostable multivibrator; 6 is a pulse extinction detection circuit; when a pulse is input within a certain period, the state is "1" (for example, the first state), and when no pulse is input, it is "0" (for example, the second state). ).

FIG. 5 is a waveform diagram for explaining FIG. 3. FIG. 5 a shows the input waveform, and FIG.
5c shows the output of the monostable multivibrator 5, and FIG. 5d shows the output of the pulse extinction detection circuit 6.

The operation shown in FIG. 4 will be explained with reference to FIG. For example, the input waveform W is the sound wave during punching with a press.
When input to the comparator 1 (as shown in FIG. 5a), the waveform portion that exceeds the reference level R is compared with the reference level R and is outputted from the comparator 1 as a pulse as shown in FIG. 5b. The monostable multivibrator 5 changes from level "1" to level "0" at the moment the pulse shown in FIG.
Outputs a pulse with a minute width like this. This pulse is inputted to the pulse extinction detection circuit 6, and if this input pulse is inputted within the period Tmin, the pulse disappears as shown in FIG.
As shown in the figure, the output of the pulse extinction detection circuit 6 becomes level "1". If the input pulse is not input within the period Tmin, the output of the pulse disappearance detection circuit 6 becomes level "0" as shown in FIG. 5d. The counter 2 counts the pulses of the pulse extinction circuit 6 for a certain period of time, and the discriminator 3 determines that an abnormality has occurred in the rotary body such as the punching press or the motor when the count value is greater than or equal to the reference count value.
If this is done, the number of bits can be reduced because low-frequency pulses arrive at the counter 2.
Furthermore, it becomes possible to take a longer time for determination.

By the way, the device of the present invention can be used, for example, to detect tool breakage by acoustic emission.
Products that can be adopted for a variety of applications, such as internal destruction detection devices for structures (oil tanks, gas tanks), nuclear pressure vessel internal component dropout detection systems, rotating machine vibration and bearing abnormality detection systems, and other application systems. It is.

That is, the present invention is suitable for detecting a phenomenon in which an input signal from a sensor (for example, an accelerometer, an acoustic emission sensor, etc.) contains a high frequency and occurs randomly.

In addition, the signal from the sensor described above is composed of a transient waveform with an extremely high frequency. Therefore, the present invention does not count the number of pulses at one time, but instead represents one wave as one pulse, and uses one wave and two waves. The number of pulses and the pulse width are not a problem because the number of pulses and the pulse width are considered to be counted and set according to the abnormal phenomenon of the target device. In other words, the element of diagnosis for such signals is the shape of a single transient waveform, and rather than making a judgment based on frequency analysis or the number of pulses that make up the waveform as in the past, the diagnosis is based on the overall shape of the waveform. The main focus is on determining. This is because, once the sensor has been determined, the nature of the abnormality is not so much the small waveforms that make up the transient waveform, but the group of waveforms that are the problem.

FIG. 6 is a block diagram showing another embodiment of the present invention, in which an integrator 4 is installed in place of the counter 2 in FIG. When the overall level rises, it may be determined whether the abnormality is normal or not by integrating the pulses of the pulse extinction detection circuit 6, and if this integrated value exceeds a reference value, it may be determined that some abnormality has occurred.

In this way, high-frequency pulses will not arrive at the integrator 4, so that the integration precision can be improved without using a very high-grade one.

As described above, according to the waveform level determination device of the present invention, a pulse extinction detection circuit is interposed between the comparator and the integrating means such as a counter or an integrator, so that the output pulse from the comparator is When input, the first state output signal is
In addition, if there is no input, a second state output signal is generated, and the state of the waveform level of the input signal input to the comparator is monitored based on this first or second state output signal. As a result, the state of the source of the input signal waveform can be determined without the need for a counter with a small number of bits or a high-precision integrator. There is an effect that can be achieved.

[Brief explanation of the drawing]

1 and 2 are block diagrams showing two types of conventional waveform level determination devices, FIG. 3 is a waveform diagram for explaining FIGS. 1 and 2, and FIG. 4 is a waveform level determination device of the present invention. FIG. 5 is a waveform diagram for explaining FIG. 4, and FIG. 6 is a block diagram showing another embodiment of the present invention. In the figure, 1 is a comparator, 2 is a counter, 3 is a discriminator, 4 is an integrator, 5 is a monostable multivibrator, and 6 is a pulse extinction detection circuit. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] 1 A comparator that outputs a comparison pulse when the transient input waveform from the source exceeds a reference level, a monostable multivibrator to which the comparison pulse of this comparator is input, and a constant output pulse of this monostable multivibrator. The first status output signal when introduced within a set period,
Further, an integrating means for counting or integrating the first and second state output signals from the pulse extinction detection circuit, each outputting a second state output signal when the pulse is not introduced within the certain period, and an output state of the integrating means. A waveform level determination device comprising a discriminator that determines a change state of the generation source according to.