JPH0127375B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic determination device used, for example, to determine the magnitude of vibration and noise of equipment.

FIG. 1 shows the configuration of an automatic determination device conventionally used for determining motor noise. In the figure, 1 is a test motor to be subjected to noise determination, 2 is a microphone, 3 is a sound level meter, and 4A to 4C are the sound level meters 3.
A filter 5 connected to the output terminal of is a quality display unit that determines and displays the quality of the motor noise based on the signals divided into required frequency components by the filters 4A to 4C.

When determining whether motor noise satisfies the standards using the automatic determination device configured as described above,
A microphone 2 is installed near the test motor 1. When the motor 1 rotates and generates noise, the noise is detected by the microphone 2 and the sound level meter 3
After the signal is amplified, each frequency component is distinguished by filters 4A to 4C. The signals for each frequency component are applied to the quality display section 5, where various comparisons of frequency components, magnitudes, etc. are performed, and the results are displayed with lamps. In this case, the types of defective products can be classified as necessary.

Although the motor noise is automatically determined in this way, with the above configuration, if the surrounding noise is louder than the motor noise during noise measurement, the noise determination is hindered.

An object of the present invention is to eliminate the above-mentioned drawbacks and provide an automatic determination device that can accurately perform determination regardless of surrounding environmental conditions.

The present invention will be explained below based on illustrated embodiments.

FIG. 2 shows an embodiment of the present invention, in which motor noise is the subject of determination. In the figure, 1 is a test motor, 2 is a microphone installed near the test motor 1 to detect motor noise, 3 is a sound level meter, 4A to 4C are filters, 5 is a quality indicator, and 6A to 6C are the Filter 4A~4C
a positive envelope detection circuit connected to the output terminal of 7;
A to 7C are the above positive envelope detection circuits 6A to 6C.
This is an arithmetic circuit which takes the output of 1 as one of its inputs, and its output end is connected to the quality display section 5.

12 is a background noise microphone; 13 is a sound level meter connected to this background noise microphone 12;
Filters 14A to 14C are connected to the output terminals of the sound level meter 13, and have the same characteristics as the corresponding filters 4A to 4C. 16A-16C
is a negative envelope detection circuit connected to the filters 14A to 14C, and its output is connected to the arithmetic circuits 7A to 14C.
7C input. That is, the arithmetic circuit 7A inputs the outputs of the detection circuits 6A and 16A. Similarly, the arithmetic circuit 7B receives the outputs of the detection circuits 6B and 16B, and the calculation circuit 7C receives the outputs of the detection circuits 6C and 16C.

Next, the operation will be explained. When the test motor 1 is stopped, the motor microphone 2 and the background noise microphone 12 detect surrounding noise, so-called background noise. In this case, the detection signals have substantially the same magnitude, and the outputs of the sound level meters 3 and 13 and the outputs of the filters 4A and 14A have substantially the same magnitude. For example, filter 14
The signal after passing through A has a waveform as shown in FIG. 3A, and the signal after passing through filter 4A has substantially the same waveform as the above signal, as shown in FIG. 3B.

Both of the above signals are amplitude modulated, and each signal is sent to envelope detection circuits 6A to 6C and 16A.
~16C is detected, resulting in signals with waveforms shown by broken lines in FIG. 3A and B. These positive and negative signals become inputs to the arithmetic circuit 7A, and the output of the arithmetic result, that is, the output resulting from the addition, becomes approximately zero. Furthermore, when the motor is stopped, the outputs of the other arithmetic circuits 7B and 7C also become zero.

In this way, when the motor 1 is in the stopped state, the outputs of all the arithmetic circuits 7A to 7C become zero, and the quality display section 5 is maintained in the non-operating state.

On the other hand, when the motor 1 is operating and motor noise is generated, the motor noise is detected by the motor microphone 2, and a signal with a waveform as shown in FIG. 4B is output from the filter 4A. arise. In this case, background noise is detected by the background noise microphone 12 in the same manner as in the above case, and after passing through the filter 14A, the waveform becomes as shown in FIG. 4A.

That is, when the motor is running, the signal from the motor microphone 2 series is transmitted to the background noise microphone 12.
The signal shown in FIG. 4C is obtained as the output of the arithmetic circuit 7A which inputs the envelope detection outputs of both signals. Although this signal is not the motor sound itself, it shows the envelope of the motor sound; when the motor sound is loud, the positive voltage becomes large, and when the motor sound is low, the positive voltage becomes small. As a result, when a reference voltage value is set, for example, in the quality display section 5, a motor with a voltage higher than the set voltage is determined to be a defective product, and a motor with a lower voltage is determined to be a good product, and these are blindly displayed. Furthermore, it is divided into frequency components by a plurality of filters, and the size and waveform of each frequency component are compared to classify defective products.

In the above embodiment, the arithmetic circuit has an addition function, but by changing the circuit configuration, it can perform subtraction,
Similar effects can be achieved even with devices that have functions such as division. Further, although a plurality of filters are provided in the embodiment, a configuration may be adopted in which only one filter is provided or no filter is provided. Furthermore, the determination target is not limited to motor noise, but can also be applied to other physical quantities.

As described above, according to the present invention, a plurality of signals including signals caused by surrounding environmental conditions are used as signals to be determined, and these signals are processed by an envelope detection circuit and an arithmetic circuit, and then compared and examined. Therefore, the main signal can be determined without being affected by unnecessary signals such as background noise, and the determination can be made accurately no matter what frequency components are included in the background noise.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a conventional automatic determination device, FIG. 2 is a block diagram showing an embodiment of the present invention, and FIGS. FIG. 1... Test motor, 2... Motor microphone, 3, 13... Sound level meter, 4A to 4C, 14A
~14C...Filter, 5...Quality display section, 6A
~6C...Positive envelope detection circuit, 7A~7C...
...Arithmetic circuit, 12...Microphone for background noise,
16A to 16C... Negative envelope detection circuit. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] 1. An envelope detection circuit provided for each of a plurality of signals to be determined, and connected to a subsequent stage of the detection circuit,
an arithmetic circuit that performs predetermined calculations using the detection output of the detection circuit as input; and a display section that is connected to a subsequent stage of the arithmetic circuit and that determines and displays whether or not standards are met based on the calculation results of the arithmetic circuit. An automatic determination device comprising: 2. The automatic determination device according to claim 1, wherein a filter having the same characteristics is provided for each signal series. 3. The automatic determination device according to claim 1 or 2, which uses output signals from an equipment noise microphone and a background noise microphone installed at required intervals as the plurality of signals to be measured.