JP3371209B2 - Ultra-low frequency vibration noise prevention device for vibration equipment - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for preventing an ultra-low frequency vibration sound generated from a vibration device such as a vibrating sieve used in muddy water shield construction or the like. . 2. Description of the Related Art Vibrating sifters used in muddy water shield construction and the like vibrate a sieve at a constant frequency to sifte materials, and a sufficient amount of material is placed on the sieve. In this state, it is the same as one large solid plate vibrating, the stroke of the vibration reaches several millimeters, and the generated vibration sound is a very low frequency sound of 20 Hz or less. Such an ultra-low frequency sound causes discomfort to residents in the vicinity of the work site, and causes adverse effects such as rattling of fittings such as windows and doors. In particular, in muddy water shield construction, a plurality of vibrating sieves are often operated simultaneously, so that a plurality of vibration sounds are superimposed to generate a beat, which has a great adverse effect. Conventionally, as a countermeasure against noise against the very low frequency sound as described above, as shown in FIGS. 9 and 10, the entire vibrating sieve is covered with a robust soundproof cover a, and opposite phases generated above and below the sieve net b. A method of reducing the transmission of the extremely low frequency sound to the outside of the soundproof cover a by making the sound pressures cancel each other, or a vibration sieve as described in Japanese Utility Model Publication No. 3-23341. A method has been proposed in which a large opening is provided in 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 be vibrated by the vibration itself of the vibrating sieve and the sound pressure, the equipment becomes large-scale. Since a conveyor entrance for supplying and discharging the material to and from the vibrating sieve is required, it is often difficult to completely cover with a soundproof cover. The soundproof cover obstructs maintenance of the vibrating screen machine and monitoring of the screen state. In the method of providing an opening in the back plate of a vibrating sieve, it is difficult to uniformly reduce the generation of vibration noise with respect to fluctuations in vibration patterns (period, phase, amplitude, etc.) due to machine operating conditions. However, there is a problem that a sufficient reduction effect cannot be expected, and the mechanical strength of the vibrating sieve becomes weak. Accordingly, an object of the present invention is to enable real-time reduction of ultra-low frequency vibration sound in response to the fluctuation even if the vibration pattern of the vibration device fluctuates. It is an object of the present invention to provide an extremely low frequency vibration sound preventing device having a high effect. [0007] The ultra-low frequency vibration sound preventing apparatus of the present invention is provided in parallel with a vibration device such as a vibrating sieve that is driven by a driving source such as a motor to generate vibration noise, and is also driven by a driving source such as a motor. Additional vibration devices that generate substantially the same vibration sound, first and second vibration sensors that detect the vibrations of these vibration devices and the additional vibration devices as electric signals A and B, respectively, and an electric signal from these vibration sensors. A low-pass filter that extracts only the very low frequency components of the signals A and B, and the difference Δf between the frequencies fA and fB of the extracted very low frequency signals A and B.
, 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.
, A second control amount calculating means for obtaining a control amount ΔD corresponding to the phase difference ΔP, and controlling the rotation speed of the drive source of the additional vibration device according to the control amount ΔC. Rotation speed control means for controlling according to ΔD. Then, the frequency difference calculating means and the first
In the processing by the control amount calculating means, it is determined whether or not the frequency difference Δf is 0, and if not, a control amount ΔC is calculated in accordance with the frequency difference Δf. The control means controls the drive source of the additional control device. After the control, the frequency difference Δf between the two signals A and B is calculated again, and the same processing is repeated until the frequency difference Δf becomes zero. In the processing by the phase difference calculating means and the second control amount calculating means, it is determined whether or not the phase difference ΔP is 180 °, and if not, the frequency of the signal B is changed according to the sign of the frequency difference Δf. Is shifted by a fixed frequency + f0 or -f0, a control amount ΔD corresponding to (ΔP−180 °) is calculated, and the rotation speed control means drives the drive source of the additional control device according to the control amount ΔD. Control the rotation speed of
After the control, the phase difference ΔP between the two signals A and B is calculated again, and the same processing is repeated until the phase difference ΔP becomes 180 °. Now, when the vibration sound generated from the vibration device is simplified as shown in FIG. 7 and represented as a sine wave, the vibration sound Fa has a phase opposite to that of the vibration sound Fa (the phase difference is 180 °) at the same frequency. If another vibration sound Fb having the same amplitude is added, these vibration sounds Fa and Fb cancel each other. According to the present invention, based on such a principle, an additional vibration device that generates a vibration sound equivalent to the vibration device to be subjected to vibration sound prevention is provided in parallel, and the additional vibration device acts as a kind of dipole sound source. Let it. Then, the vibration of the vibration device and the additional vibration device is detected as an electric signal so that the vibration of the vibration device serving as the dipole sound source can respond to the fluctuation of the vibration pattern of the vibration device every moment. The drive source of the additional vibration device is automatically controlled so that only the component is extracted to obtain the phase difference, and the phase difference is always in the opposite phase (180 °). For example, when the driving source is a motor, the number of rotations of the motor is controlled. Further, if the frequency of the vibration of the vibration device and the frequency of the vibration of the additional vibration device deviate, the same control is performed so that the latter vibration matches the former vibration. An embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows an example in which the present invention is applied to a vibrating sieve used in muddy water shield construction. Work building 1 at the work site
In the basement 2, a vibration sieving machine 4 whose vibration noise is to be prevented is installed on the vibration isolating table 3, and the vibration sieving machine having substantially the same structure as the vibration sieving machine 4 is provided. On the vibration isolator 3 as the additional vibration device 5. FIG. 2 shows a schematic configuration of a vibration sound preventing apparatus according to the present invention. Known vibration sensors 6 and 7 are attached to the vibrating sieve 4 and the additional vibrating device 5, respectively. Vibrations of the vibrating sieve 4 and the additional vibrating device 5 are detected as analog electric signals by the respective vibration sensors 6 and 7. You.
Now, the detected analog electric signals are respectively A and B
Then, these signals A and B are subjected to waveform shaping by the waveform shaping unit 8 and analog / digital conversion by the input unit 9 and then C
The data is input to the arithmetic control unit 10 including the PU. Vibration sensor 6
No. 7 only needs to be able to directly or indirectly detect the mechanical vibration of the vibrating screen 4 and the additional vibrating device 5 as an electric signal, and the detection method is not limited. The signals A and B input to the arithmetic and control unit 10 are compared in terms of their frequencies and phases by using digital amounts, and the arithmetic and control unit 10 controls the signals A and B according to the frequency difference and the phase difference of the signal B with respect to the signal A. The amount is calculated. The control amount is output as an analog electric signal from the control signal output unit 11 to the additional vibrating device 5, and the additional vibrating device 5 is automatically controlled, that is, the vibrating sound cancels the vibrating sound of the vibrating sieve 4. Is controlled to occur. FIG. 3 is a block diagram more specifically showing the ultra-low frequency vibration sound preventing apparatus according to the present invention than FIG. The vibrating sieving machine 4 and the additional vibrating device 5 each include a motor 12.1
The rotation of 3 vibrates the sieve screen (not shown). The vibrating sieve 4 is used to actually sieve the material through a sieve screen.
Even if it is the same as above, it is used as a kind of dipole sound source that generates the same vibration sound and not used for sieving purposes. Motors 12 and 13 are connected to inverters 14 and
The number of rotations 15 can be controlled arbitrarily. Note that the additional vibration device 5 may be a dedicated one. Further, the vibrating sieve 4 and the additional vibrating device 5 include a motor 12
A structure that vibrates with a drive source other than 13 may be used. The analog electric signals from the vibration sensor 6 of the vibration sieving machine 4 and the vibration sensor 7 of the additional vibration device 5 are respectively amplified by amplifiers 16 and 17 and then, by a low-pass filter 18, to a very low frequency component (as described above). 20 Hz or less). And these two signals A and B are
The signals 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
Is digitally processed to determine their frequency, frequency difference and phase difference. If there is a difference between the frequency of the signal A and the frequency of the signal B, a control amount (digital amount) C according to the difference,
When there is a phase difference, a control amount (digital amount) D corresponding to the difference is output. The output control amounts C and D are
The signal is converted into an analog voltage signal by the D / A converter 21 and input to the inverter 15 of the additional vibration device 5 to automatically control the rotation speed of the motor 7. FIGS. 4 to 6 show the flow of arithmetic and control processing performed in the computer 20. FIG. FIG. 4 shows a main routine. When this is started, first, at step 5
0, the frequency fA of the very low frequency signal A and the signal B
Is determined in step 51 to determine whether the determined frequencies fA and fB match. If they do not match, the process of the frequency tuning subroutine of FIG. 5 is performed at step 52, and then the process of the phase tuning subroutine of FIG. 6 is performed at step 53. If fA and fB match, the process of the phase tuning subroutine is performed without passing through the frequency tuning subroutine. Thereafter, it is determined in step 54 whether or not there is a stop command.
The processing of 51, 52, 53 or the processing of 50, 51, 53 is repeated at a fixed 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 or not 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 the signal B. If they do not match, a control amount ΔC corresponding to Δf is calculated in step 62, and then in step 63, the rotation speed of the motor 13 of the additional control device 5 is controlled according to the control amount ΔC. After the control, the process returns to step 60, where the frequency difference Δf between the two signals A and B is calculated again. If Δf becomes 0, the process is terminated. In the phase tuning subroutine shown in FIG. 6, a phase difference .DELTA.P of the signal B with respect to the signal A is calculated in step 70,
In step 71, it is determined whether or not the difference ΔP is 180 °, that is, whether or not the phases are in opposite phases. If not, step 72
And the frequency of the signal B is set to a constant frequency + f according to the sign of Δf.
After shifting by 0 or -f0, a control amount .DELTA.D corresponding to (.DELTA.P-180.degree.) Is calculated in step 73, and the rotational speed of the motor 13 of the additional control device 5 is controlled in step 74 according to the control amount .DELTA.D. I do. After the control, the process returns to step 70, where the phase difference ΔP between the two signals A and B is calculated again. When ΔP becomes 180 °, the process ends. If the rotation speed of the motor 13 of the additional control device 5 is controlled every moment so that the frequency tuning and the phase tuning are established between the vibrating sieve 4 and the additional vibrating device 5 as described above, The vibration sound of the sieve 4 and the vibration sound of the additional vibration device 5 always cancel each other, so that it is possible to prevent the adverse effects due to the extremely low frequency sound. According to the experiment, when the very low frequency sound generated from the vibrating sieve 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 of etc. has been greatly reduced. FIG. 8 shows actual measurement data obtained by measuring the sound pressure at different measurement points when the method of the present invention is performed and when it is not performed. According to the present invention, an additional vibration device for generating a vibration sound equivalent to the vibration device to be subjected to vibration sound prevention is provided along with the vibration device, and the additional vibration device is used as a kind of dipole sound source. When the vibration pattern of the vibration device fluctuates, it is possible to reduce the vibration sound in real time, even if the vibration pattern of the vibration device fluctuates. The reduction effect is high, and the generation of extremely low frequency sound can be economically prevented.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an installation diagram of an embodiment in which an apparatus according to the present invention is applied to a vibrating sieve in muddy water shield construction. FIG. 2 is a schematic configuration diagram of an ultra-low frequency vibration sound preventing device according to the present invention. FIG. 3 is a block diagram of the same device. FIG. 4 is a flowchart of a main routine of calculation and control processing performed in a computer of the same 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 for explaining that noise is reduced by adding a vibration sound having an opposite phase. FIG. 8 is a line graph showing actual measurement data obtained by measuring sound pressures at different measurement points when the apparatus of the present invention is applied and when it is not applied. FIG. 9 is a schematic configuration diagram of a conventional example in which the entire vibrating sieve is covered with a soundproof cover to prevent sound, and shows a case where a sieve mesh vibrates upward. FIG. 10 is a view similar to FIG. 9 when the sieve mesh vibrates downward. [Description of Signs] 4 Vibration sieve 5 Additional vibration device 6/7 Vibration sensor 8 Waveform shaping unit 9 Input unit 10 Operation control unit 11 Control signal output unit 12/13 Motor 14/15 Inverter 16/17 Amplifier 18 Low pass filter 19 A / D converter 20 Computer 21 D / A converter

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Yasuaki Ishida 2 Tobanjima Construction, Sanbancho, Chiyoda-ku, Tokyo (56) References JP-A-59-65636 (JP, A) JP-A-59-69548 (JP, A) Japanese Patent Publication No. 54-28901 (JP, B1) (58) Fields investigated (Int. Cl. ⁷ , DB name) G10K 11/178 B07B 1/46

Claims (1)

(57) [Claims 1] A vibration source such as a vibrating sieve which is driven by a drive source such as a motor to generate a vibration sound is juxtaposed, and is also driven by a drive source such as a motor. Additional vibration devices that generate substantially the same vibration sound, first and second vibration sensors that detect the vibrations of these vibration devices and additional vibration devices as electric signals A and B, respectively, and electric signals from these vibration sensors. A low-pass filter that extracts only the very low frequency components of A and B, and the frequency fA of both the extracted very low frequency signals A and B.
frequency difference calculating means for calculating a difference Δf of fB, 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. Phase difference calculating means for calculating; second control amount calculating means for obtaining a control amount ΔD corresponding to the phase difference ΔP; and controlling the rotation speed of the drive source of the additional vibration device according to the control amount ΔC. A rotation speed control means for controlling according to ΔD. In the processing by the frequency difference calculation means and the first control amount calculation means, it is determined whether or not the frequency difference Δf is 0,
If it is not 0, a control amount ΔC corresponding to the frequency difference Δf is calculated, and then the drive source of the additional control device is controlled by the rotation speed control means according to the control amount ΔC. Is calculated again, and the same processing is repeated until the frequency difference Δf becomes 0. In the processing by the phase difference calculating means and the second control amount calculating means, whether the phase difference ΔP is 180 ° Judge whether or not
If it is not 180 °, the signal B depends on the sign of the frequency difference Δf.
Is shifted by a fixed frequency + f0 or -f0, a control amount ΔD corresponding to (ΔP−180 °) is calculated, and according to the control amount ΔD, the rotation speed control means controls the additional control device. Controlling the number of rotations of the drive source, calculating the phase difference ΔP between the two signals A and B again after the control, and repeating the same processing until the phase difference ΔP becomes 180 °. Ultra-low frequency vibration noise prevention device.