JPH05188978A - Method and device for preventing noise sound of vibrating equipment - Google Patents

Abstract

PURPOSE:To reduce the vibration noise in real time momentarily corresponding to variation of the vibration pattern of the vibrating equipment even when the vibration pattern varies and to prevent an extremely low frequency sound from being generated. CONSTITUTION:A vibrating screen 4 which is driven by a driving source such as a motor 12 to generate a vibration sound is provided with an additional vibrating device 5 which is driven by a driving source such as a motor 13 to generate nearby the same vibration sound, and the vibrations of those vibrating equipment and additional vibrating device 5 are detected as electric signals A and B and then compared with each other to find a controlled variable DELTAD with which the electric signal A based upon the vibration of the vibrating equipment is opposite in phase to the electric signal B based upon the vibration of the additional vibrating equipment, thereby automatically controlling the driving source for the additional vibrating equipment according to the controlled variable DELTAD.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for preventing vibration noise generated from a vibrating device such as a vibrating screener used in muddy water shield work.

[0002]

2. Description of the Related Art A vibrating sieving machine used for muddy water shield work is for sieving materials by vibrating the sieving net at a constant frequency, and when sufficient material is placed on the sieving net. It is the same as one large solid plate vibrating, the stroke of the vibration reaches several mm, and the generated vibration sound becomes an ultra low frequency sound of 20 Hz or less. Such infrasound causes unpleasant sensation to residents around the work site and causes bad effects such as rattling fittings such as windows and doors. In particular, in the muddy water shield construction, since a plurality of vibrating screeners are often operated simultaneously, a plurality of vibrating noises are superimposed on each other to cause a humming, which has a great adverse effect.

Conventionally, as a noise countermeasure against the above-mentioned super low frequency sound, as shown in FIGS. 9 and 10, the entire vibration sieving machine is covered with a robust soundproof cover a to prevent the reverse phase generated above and below the sieve screen b. A method of reducing the propagation of infrasound outside the soundproof cover a by canceling out the sound pressures, or a vibrating sieve as described in Japanese Utility Model Publication No. 3-23341. A method has been proposed in which a large opening is provided on the back plate of the machine to reduce the generation of vibration noise.

However, the method of covering with a soundproof cover has the following problems. Since the soundproof cover itself must have a structure having sufficient strength so as not to vibrate due to the vibration itself of the vibrating screener and the sound pressure, it is a large-scale facility. In many cases, it is difficult to completely cover with a soundproof cover because an entrance / exit for a conveyor for supplying / discharging materials to / from the vibrating screener is required. The soundproof cover interferes with maintenance of the vibrating screener and monitoring of the sieving condition.

In addition, with the method of providing the opening in the back plate of the vibrating screener, it is difficult to uniformly reduce the generation of vibrating noise with respect to fluctuations in the vibration pattern (cycle, phase, amplitude, etc.) due to machine operating conditions. In addition, there is a problem that a sufficient reduction effect cannot be expected and the mechanical strength of the vibrating screener becomes weak.

Therefore, an object of the present invention is to reduce vibration noise in real time, even if the vibration pattern of the vibrating device fluctuates, in real time by responding to the fluctuation, and to obtain a high vibration reduction effect. It is to provide a method and a device for preventing sound.

According to the present invention, in addition to a vibrating device such as a vibrating screener which is driven by a drive source such as a motor to generate a vibrating sound, an additional vibrating sound which is also driven by a drive source such as a motor is generated. A vibration device is placed side by side. Then, the respective vibrations of the vibrating device and the additional vibrating device are detected as electric signals A and B, and the detected both electric signals A and B are compared, and the additional vibration is added to the phase of the electric signal A due to the vibration of the vibrating device. A control amount ΔD at which the phase of the electric signal B due to the vibration of the device is reversed is obtained, and the drive source of the additional vibration device is automatically controlled according to the control amount ΔD.

After comparing the frequencies fA and fB of both electric signals A and B, a control amount ΔC corresponding to the difference Δf is obtained, and after automatically controlling the drive source of the additional vibration device according to the control amount ΔC,
As described above, the control amount ΔD at which the phase of the electric signal B due to the vibration of the additional vibration device is opposite to the phase of the electric signal A due to the vibration of the vibrating device is obtained, and the drive source of the additional vibration device is obtained according to the control amount ΔD. Should be controlled automatically.

[0009]

When the vibration sound generated from the vibrating device is simplified and expressed as a sine wave in FIG. 7, the vibration sound Fa has the same frequency but the opposite phase (phase difference of 180 °) and the same amplitude. If another vibration sound Fb is added, these vibration sounds Fa and Fb cancel each other out.

On the basis of such a principle, the present invention has an additional vibrating device for producing a vibrating sound equivalent to that of the vibrating device for which the vibrating noise is to be prevented, and acts as a kind of dipole sound source. Let Then, in order that the vibration of the additional vibrating device, which is the dipole sound source, can respond to the fluctuation of the vibration pattern of the vibrating device moment by moment, the vibration of these vibrating device and the additional vibrating device is detected as an electrical signal and the phase difference is detected. The drive source of the additional vibration device is automatically controlled so that it is always in the opposite phase (180 °). For example, when the drive source is a motor, the rotation speed of the motor is controlled. If the frequency of the vibration of the vibrating device and the frequency of the vibration of the additional vibration device deviate from each other, the latter vibration is similarly controlled so as to match the former vibration.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. Figure 1 shows an example applied to a vibrating screener used in muddy water shield work. Work building 1 at the work site
In the basement 2 of the above, when the vibration sieving machine 4 targeted for preventing the generation of vibration noise is installed on the vibration isolation table 3, the vibration sieving machine having substantially the same structure as the vibration sieving machine 4 is installed. Are additionally placed on the vibration isolation table 3 as the additional vibration device 5.

FIG. 2 shows a schematic structure of a vibration noise prevention apparatus according to the present invention. Known vibration sensors 6 and 7 are attached to the vibrating screener 4 and the additional vibrating device 5, respectively, and the vibrations of the vibrating screener 4 and the additional vibrating device 5 are detected as analog electric signals by the respective vibrating sensors 6 and 7. It
Now, the detected analog electrical signals are respectively A and B
Then, these signals A and B are waveform-shaped by the waveform shaping unit 8, analog / digital converted by the input unit 9, and then C
It is input to the arithmetic and control unit 10 including the PU. Vibration sensor 6
The number 7 may be any type as long as it can directly or indirectly detect the mechanical vibration of the vibrating screener 4 and the additional vibrating device 5 as an electric signal.

The signals A and B input to the arithmetic control unit 10 are compared with each other in terms of frequency and phase as digital values, and the arithmetic control unit 10 performs control according to the frequency difference and phase difference of the signal B with respect to the signal A. The amount is calculated. Then, the control amount is output from the control signal output unit 11 as an analog electric signal to the additional vibrating device 5, and the additional vibrating device 5 automatically controls, that is, a vibrating sound that cancels the vibrating sound of the vibrating screener 4. Is controlled to occur.

FIG. 3 is a block diagram showing the vibration noise prevention apparatus according to the present invention more specifically than FIG. The vibrating screener 4 and the additional vibrating device 5 vibrate a screen (not shown) by rotation of the motors 12 and 13, respectively. Although the vibrating screener 4 is used to actually screen the material with a screen, the additional vibrating device 5 produces a vibration sound equivalent to that of the vibrating screener 4 even though the structure is the same as that described above. It is used as a kind of generated dipole sound source and is not used for the purpose of sieving. The motors 12 and 13 can be controlled in their rotational speeds by inverters 14 and 15, respectively. The additional vibration device 5 may be a dedicated one. Further, the vibrating screener 4 and the additional vibrating device 5 may have a structure that vibrates by a drive source other than the motors 12 and 13.

The analog electric signals from the vibration sensor 6 of the vibrating screener 4 and the vibration sensor 7 of the additional vibrating device 5 are amplified by the amplifiers 16 and 17, respectively, and then extracted by the low-pass filter 18 only for ultra-low frequency components. .. Both signals A and B are converted into digital signals by the A / D converter 19 and input to the computer 20.

The computer 20 receives the input signals A and B
Are digitally processed to obtain their frequency, frequency difference and phase difference, and when there is a difference in the frequency of the signal B with respect to the frequency of the signal A, the control amount (digital amount) C corresponding to the difference,
When there is a phase difference, the control amount (digital amount) D corresponding to the difference is output. The output control quantities C and D are
The analog voltage signal is converted by the D / A converter 21 and input to the inverter 15 of the additional vibration device 5, and the rotation speed of the motor 7 is automatically controlled.

4 to 6 show the flow of calculation and control processing performed in the computer 20. FIG. 4 shows the main routine, and if this is the start, first step 5
At 0, the frequency fA of the signal A and the frequency f of the signal B
B is obtained, and it is determined in step 51 whether or not the obtained frequencies fA and fB match. If they do not match, the frequency tuning subroutine of FIG. 5 is processed in step 52, and then the phase tuning subroutine of FIG. 6 is processed in step 53. If fA and fB match, the phase tuning subroutine is processed without passing through the frequency tuning subroutine. Thereafter, it is determined in step 54 whether or not there is a stop command, and if there is no stop command, steps 50, 51, 52, ...
The processing of 53 or the processing of 50.51.53 is repeated at a constant cycle.

In the frequency tuning subroutine of FIG. 5, the difference Δf between the frequency fA of the signal A and the frequency fB of the signal B is calculated in step 60, and in step 61 it is determined whether the difference Δf is 0, that is, the signal A. It is determined whether the frequency fB of the signal B matches the frequency fA of. If they do not match, the control amount ΔC corresponding to Δf is calculated in step 62, and then the rotation speed of the motor 13 of the additional control device 5 is controlled in accordance with this control amount ΔC in step 63. After the control, the process returns to step 60, the frequency difference Δf between the two signals A and B is calculated again, and if Δf becomes 0, the process ends.

In the phase tuning subroutine of FIG. 6, the phase difference ΔP of the signal B with respect to the signal A is calculated in step 70,
In step 71, it is determined whether the difference ΔP is 180 °, that is, whether the difference ΔP is in the opposite phase. If the phases are not opposite, step 72
Then, the frequency of the signal B is kept at a constant frequency + f according to the plus or minus of Δf.
After shifting by 0 or -f0, the control amount ΔD corresponding to (ΔP-180 °) is calculated in step 73, and the rotation speed of the motor 13 of the additional control device 5 is controlled in accordance with this control amount ΔD in step 74. To do. After the control, the process returns to step 70, the phase difference ΔP between the two signals A and B is calculated again, and when ΔP reaches 180 °, the process ends.

If the number of revolutions of the motor 13 of the additional control device 5 is controlled moment by moment so that the frequency tuning and the phase tuning are established between the vibrating screener 4 and the additional vibrating device 5 as described above, the vibration is generated. The vibrating sound of the sieve 4 and the vibrating sound of the additional vibrating device 5 always cancel each other out, and the harmful effect of the infrasound can be prevented. According to the experiment, when the infrasound generated from the vibration sieving machine 4 is 14 Hz, there is a reduction effect of about 15 dB in the work building 1 and about 5 to 10 dB outdoors in FIG. The rattling has been greatly reduced. FIG. 8 shows actual measurement data obtained by measuring the sound pressure with and without the method of the present invention at different measurement points.

[0021]

According to the present invention, an additional vibrating device for generating a vibrating sound equivalent to the vibrating device to which the vibrating noise is to be applied is arranged in parallel, and the additional vibrating device acts as a kind of dipole sound source. Even if the vibration pattern of the vibration device fluctuates, it is possible to reduce the vibration noise in real time by responding to the fluctuations even when the vibration pattern of the vibration device fluctuates. It is possible to prevent generation of infrasound at high cost and economically.

[Brief description of drawings]

FIG. 1 is an installation diagram of an embodiment in which the method according to the present invention is applied to a vibrating screener in muddy water shield work.

FIG. 2 is a schematic configuration diagram of a vibration noise prevention device according to the present invention.

FIG. 3 is a block diagram of the vibration prevention device.

FIG. 4 is a flowchart of a main routine of calculation and control processing performed in a computer of the vibration prevention device.

FIG. 5 is a flowchart of a frequency tuning subroutine.

FIG. 6 is a flowchart of a phase tuning subroutine.

FIG. 7 is a waveform diagram illustrating that noise is reduced by adding a vibration sound of opposite phase.

FIG. 8 is a line graph showing actual measurement data obtained by measuring sound pressure at different measurement points when the method of the present invention is carried out and when it is not carried out.

FIG. 9 is a schematic configuration diagram of a conventional example in which the entire vibration sieving machine is covered with a soundproof cover to prevent noise, and shows a case where the sieve screen vibrates upward.

FIG. 10 is a view similar to FIG. 9 when the screen is vibrated downward.

[Explanation of symbols]

 4 Vibration sifter 5 Additional vibration device 6/7 Vibration sensor 8 Waveform shaping part 9 Input part 10 Arithmetic control part 11 Control signal output part 12/13 Motor 14/15 Inverter 16/17 Amplifier 18 Low-pass filter 19 A / D converter 20 Computer 21 D / A converter

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasuaki Ishida 2 Sanbancho, Chiyoda-ku, Tokyo Tobishima Construction Co., Ltd.

Claims (5)

[Claims] 1. An additional vibrating device, which is driven by a drive source such as a motor to generate a vibrating sound, and which is driven by a drive source such as a motor, to generate substantially the same vibrating sound, to a vibrating device such as a vibrating screener. Are arranged side by side, and the respective vibrations of the vibrating device and the additional vibrating device are detected as electric signals A and B, and the detected both electric signals A and B are compared, and the phase of the electric signal A due to the vibration of the vibrating device is compared. Prevention of vibration noise in a vibrating device, characterized in that a control amount ΔD in which the phase of the electric signal B due to the vibration of the additional vibration device is opposite phase is obtained, and the drive source of the additional vibration device is automatically controlled according to the control amount ΔD. Method. 2. The frequencies fA and fB of the electric signals A and B, respectively.
Are compared to obtain a control amount ΔC according to the difference Δf, and the drive source of the additional vibration device is automatically controlled according to the control amount ΔC, and then the vibration of the additional vibration device with respect to the phase of the electric signal A caused by the vibration of the vibrating device. 2. The vibration amount in the vibrating device according to claim 1, wherein a control amount ΔD at which the phase of the electric signal B due to the above is obtained and the drive source of the additional vibration device is automatically controlled according to the control amount ΔD. Prevention method. 3. The frequencies fA and fB of the electric signals A and B, respectively.
Are compared to obtain a control amount ΔC according to the difference Δf, and the drive source of the additional vibration device is automatically controlled according to the control amount ΔC, and then the vibration of the additional vibration device with respect to the phase of the electric signal A caused by the vibration of the vibrating device. The phase difference ΔP of the electric signal B
When the phase difference ΔP is not 180 °, the frequency of the electric signal B is shifted by a certain amount (ΔP−180 °).
3. The method for preventing vibration noise in a vibrating device according to claim 2, wherein a control amount ΔD according to is calculated, and the drive source of the additional vibration device is automatically controlled according to the control amount ΔD. 4. A vibration source, such as a vibrating screener, which is driven by a drive source such as a motor to generate a vibrating sound, is placed in parallel, and is also driven by a drive source such as a motor to generate substantially the same vibrating sound. The additional vibration device, the first and second vibration sensors that detect the vibrations of the vibration device and the additional vibration device as electric signals A and B, respectively, and the frequencies fA and fB of the electric signals A and B from these vibration sensors. A frequency difference calculating means for calculating the difference Δf, a first control amount calculating means for obtaining a control amount ΔC corresponding to the frequency difference Δf, and a phase difference ΔP of the electric signal B with respect to the phase of the electric signal A. The phase difference calculation means, the second control quantity calculation means for obtaining the control quantity ΔD corresponding to the phase difference ΔP, and the rotational speed of the drive source of the additional vibration device are controlled according to the control quantity ΔC, and then the above Δ
And a rotation speed control means for controlling according to D. 5. The vibration noise preventive apparatus for a vibrating device according to claim 4, wherein the additional vibrating device has the same structure as the vibrating device.