JP3997169B2 - Water treatment method and water treatment apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a water treatment method and a water treatment apparatus, and more particularly to a water treatment method and a water treatment apparatus suitable for use in sterilization of bacteria in drinking water, a circulating bath, and the like.
[0002]
[Prior art]
Conventionally, it has been known that strong ultrasonic waves have a bactericidal effect, and a bactericidal apparatus has been developed that uses this bactericidal effect to sterilize problematic bacteria in drinking water and a circulating bath. And the technique described in patent document 1, patent document 2, etc. is known as a prior art regarding the water treatment apparatus as this kind of sterilizer, for example.
[0003]
The above-described water treatment apparatus according to the prior art uses the resonance of the ultrasonic generation mechanism to apply ultrasonic waves having a large amplitude (about 1 μm) to the water to generate cavitation, which occurs at the time of contraction. Bacteria are mechanically destroyed by high-temperature, high-pressure, high-speed water flow. It is said that sterilization by ultrasonic waves is generally sterilized by oxidation by sonochemical effect, but when using a low frequency of about 28 kHz, it is mechanically pulverized against large bacteria of about 5 μm. The effect is confirmed.
[0004]
In addition, for example, Patent Document 3 discloses a technique related to an ultrasonic device that can change the frequency of an ultrasonic wave so as to maintain the resonance point of an ultrasonic vibrator that varies depending on the state of a liquid that applies ultrasonic waves. It is described in Patent Document 4, Patent Document 5, and the like.
[0005]
[Patent Document 1]
JP 2001-9448 A
[0006]
[Patent Document 2]
JP 2001-334264 A
[0007]
[Patent Document 3]
JP-A-6-71226
[0008]
[Patent Document 4]
JP-A-7-265794
[0009]
[Patent Document 5]
JP 2001-212514 A
[0010]
[Problems to be solved by the invention]
When the water treatment apparatus according to the prior art described above is actually operated, the optimum ultrasonic frequency for cavitation may fluctuate due to the influence of water temperature, flow velocity, impurities, etc. Has the problem that it may not be possible.
[0011]
In addition, the above-described prior art has a problem that when used in the absence of water, the amplitude becomes abnormally large and there is a risk that the device may be broken, and the device itself is caused by cavitation generated by the device. It has a problem that it is scraped off and causes a change in resonance frequency.
[0012]
The object of the present invention is to solve the above-mentioned problems of the prior art, enable automatic tracking for the frequency of ultrasonic waves and automatic control of amplitude so that optimum cavitation occurs, and resonance caused by the device itself being shaved. Water treatment that makes it possible to notify abnormalities such as when the frequency change exceeds the operating range or when there is no water, and to issue an alarm when either the frequency or amplitude deviates from the tracking range It is to provide a method and a water treatment apparatus.
[0013]
[Means for Solving the Problems]
According to the present invention, the object is to control the vibrator of the sterilization cell and to detect the amplitude of the vibrator in a water treatment method for sterilizing bacteria in water by applying ultrasonic vibration to water to be treated. The frequency of the signal applied to the vibrator is detected, and based on the detected amplitude of the vibrator and the detected signal frequency, the amplitude and the vibration frequency of the vibrator are controlled to become target values. Then, the amplitude control of the vibrator at that time is performed by applying a pair of PWM signals having phase changes symmetrical to each other according to the magnitude of the amplitude to the vibrator via the drive transformer, thereby obtaining the vibration phase. To control the amplitude without changing Is achieved.
[0014]
Another object of the present invention is to provide a means for detecting the amplitude of a vibrator and a vibrator in a water treatment apparatus for sterilizing bacteria in water by driving and controlling a vibrator of a sterilization cell and applying ultrasonic vibration to water to be treated. A means for detecting the frequency of the signal applied to the control means, a control means for controlling the amplitude of the vibrator to be a target value based on the detected amplitude of the vibrator, and a frequency of the detected signal. Control means for controlling the vibration frequency of the vibrator to be a target value. The amplitude control means of the vibrator synthesizes the pair of PWM signals with the PWM signal generation means for generating a pair of PWM signals having phase changes symmetrical to each other according to the magnitude of the amplitude. And a driving transformer applied to the vibrator. Is achieved.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of a water treatment method and a water treatment apparatus according to the present invention will be described in detail with reference to the drawings.
[0016]
FIG. 1 is a block diagram showing a system configuration when a water treatment apparatus according to an embodiment of the present invention is used for sterilization of a circulating bath, and FIG. 2 is a diagram showing a configuration of a piping system in FIG. 1 and 2, 101 is a bathtub, 102 is a chlorine source, 103 is a hair collector, 104 is a pump, 105 is a filter, 106 is a piping system, 107 is a wiring system, 108 is a piping pipe, and 109 to 111 are Valve, 112 is a shunt, 113 is a merger, 114 is a water treatment device, 115 is a heater, 116 is a former breaker, 117 is an alarm display device, 201 is a rainproof power terminal, 202 is a leakage breaker / power switch (SW ), 203 is a pilot lamp, 204 is an alarm lamp, 205 is ground, an alarm terminal, 206 is a bolt stopper, and 207 is a faucet.
[0017]
The system using one or more water treatment devices 114 according to an embodiment of the present invention for the sterilization of a circulating bath is a chlorine source that sterilizes chlorine while circulating the water in the bath 101 as shown in FIG. 102, a hair collector 103 that removes relatively large dust and the like, a pump 104 that circulates water, a filter 105 that removes fine dust, and a water treatment device 114 according to an embodiment of the present invention after filtering water. And a heating system 115 for heating the sterilized water, and the heated water is returned to the bathtub 101.
[0018]
The piping system 106 is branched upstream of a piping pipe 108 having two branches, a valve 109 provided in the middle of the two branches, and valves 110 and 111 provided in each of the two branched piping pipes. The flow divider 112 is provided at the front end of the pipe and the merger 113 is provided at the front end of the pipe branched on the downstream side. And as shown to Fig.2 (a), the diverter 112 is a piping pipe which distributes the water before a process to the 1 or several water treatment apparatus 114 (it is only shown with the thin line in Fig.2 (a)). In addition, the merger 113 is connected to a piping pipe that takes in the treated water from the water treatment device 114.
[0019]
One or a plurality of water treatment devices 114 are connected to a wiring system 107 for supplying AC 100V power via the original breaker 116 and displaying an alarm on the alarm display device 117. As will be described later, a sterilization cylinder constituting an ultrasonic sterilizer is provided inside the water treatment device 114. As shown in FIGS. 2 (a) and 2 (b), the water treatment device 114 has a width of 30 cm, a depth of 30 cm, and a height of about 40 cm. Are arranged separately on the front side and the back side of the casing of the water treatment device 114, and on the front side of the casing are a rainproof power terminal 201, an earth leakage breaker / power switch 202, a pilot lamp 203, an alarm A lamp 204, a ground, and an alarm terminal 205 are disposed, and a water faucet 207 for a pipe connected to the flow divider 112 and the merger 113 is disposed on the back side. Further, although not shown in FIG. 2, a bolting metal fitting 206 is provided in a bowl-shaped portion on the bottom surface of the housing.
[0020]
The circulation tub sterilization system shown in FIG. 1 configured as described above is used in a state where the valve 109 is closed and the valves 110 and 111 are opened in the operating state. And the water which passed the filter 105 is supplied to the several water treatment apparatus 114 via the valve | bulb 110 and the flow divider 112, and after sterilization by an ultrasonic wave by the water treatment apparatus 114 demonstrated in detail later, It is sent to the heater 115 through the merger 113 and the valve 111, heated to a predetermined temperature by the heater 115, and then returned to the bathtub.
[0021]
FIG. 3 is a block diagram showing the configuration of the water treatment apparatus according to one embodiment of the present invention. Next, the configuration of the water treatment apparatus 114 connected according to FIGS. 1 and 2 will be described with reference to FIG. In FIG. 3, 301 is a sterilization cell, 302 is a drive transformer, 303 is a current detection unit, 305 is a comparator, 306 is a sample and hold circuit, 309 is a frequency control unit, 312 is an amplitude sensor, 314 is an amplitude detection circuit, and 317 is Amplitude control unit, 320 is an alarm issuing unit, 321 is an alarm terminal, 322 is a clock source, 323 is a PLL, timing generation circuit, 324 is a PWM signal generation circuit, 325 is a driver, 326 is a power supply circuit, 327 is a ground terminal, 328 Is a frequency detector, 330 and 331 are vibrators, 332 is a vibration synthesizer, 333 is a cylindrical container, and 334 is a sterilization cylinder.
[0022]
As shown in FIG. 3, a water treatment apparatus according to an embodiment of the present invention includes a sterilization cell 301 configured as described later, a drive circuit that drives vibrators 330 and 331 in the sterilization cell 301, and a drive circuit. And a power supply circuit 326 for supplying the necessary power.
[0023]
In FIG. 3, a sterilization cell 301 is provided with a sterilization cylinder 334 made of a metal lump inside a cylindrical container 333, and water to be treated is introduced from the lower surface of the cylindrical container 333 between the sterilization cylinder 334 and the inner wall of the cylindrical container 333. Accordingly, the sterilized water is extracted from the upper part of the cylindrical container 333. The sterilization cylinder 334 is coupled to a vibration synthesizer 332 that synthesizes the vibrations of the two Langevin type vibrators 330 and 331 driven in the ultrasonic region, and the vibration transmitted from the vibration synthesizer 332 flows through the surrounding water. To communicate. The water flowing around the sterilization cylinder 334 causes cavitation by the vibration of the applied ultrasonic waves to sterilize the bacteria present in the water.
[0024]
The entire mechanical part including the vibrators 330 and 331, the vibration synthesizer 332, and the sterilization cylinder 333 in the sterilization cell 301 described above constitutes a resonator when viewed from the drive circuit that drives the vibrators 330 and 331. The frequency of the signal applied to the vibrators 330 and 331 is set to the resonance frequency. As a result, cavitation can be generated by efficiently applying large vibrations to the water to be signaled. However, the resonance frequency described above may be shifted due to the influence of water temperature, flow velocity, impurities, etc.In the embodiment of the present invention, the frequency applied to the vibrator is set corresponding to the resonance frequency deviation of the mechanism portion described above. The follow-up control is performed, and the amplitude is also controlled so as to be maintained at a set size.
[0025]
Next, a drive circuit that controls the vibrators 330 and 331 by controlling the frequency and amplitude as described above will be described.
[0026]
The PLL and timing generation circuit 323 receives a signal from the clock source 322 that is a timing source for the driving circuit according to the embodiment of the present invention constituted by a digital circuit, and a frequency according to a frequency signal that drives the vibrators 330 and 331. And the frequency signal is passed to a PWM signal generation circuit 324 that generates a sine wave based on a pulse width modulation signal, and a sample timing signal 307 is supplied to a sample hold circuit 306 in the frequency detection unit 328, and its sensitivity at the time of manufacture. The timing signal 315 is supplied to the amplitude detection circuit 314 in which is adjusted.
[0027]
The PWM signal generation circuit 324 that has received the frequency signal from the PLL and timing generation circuit 323 generates a sine wave by the pulse width modulation signal to generate a PWM signal corresponding to the frequency signal, and the PWM signal is sent to the driver 325. give. The driver 325 is configured by a class D amplifier (an amplifier that amplifies digital binary signals of 0 and 1 to a large voltage). A class D amplifier that amplifies a binary signal can be configured by a switch, and can perform amplification more efficiently than linear amplifiers such as class A and class B amplifiers.
[0028]
The signal amplified by the driver 325 is applied to the vibrators 330 and 331 of the sterilization cell 301 via the drive transformer 302 that matches the impedance between the driver and the vibrator, and the water flowing in the sterilization cell 301 is described above. Used to sterilize.
[0029]
A frequency detection unit 328 including a current detection unit 303, a comparator 305, and a sample and hold circuit 306 is provided on the primary side (the side connected to the driver 325) of the drive transformer 302 described above. The current detection unit 303 includes a transformer, a resistor, and the like. The current detection unit 303 detects a current flowing through the driving transformer 302, compares the current monitor signal 304 as a signal corresponding to the detected current with the reference voltage, A binary value is given to the comparator 305.
[0030]
The sample and hold circuit 306 stores and holds the output from the comparator 305 at the time indicated by the sample timing signal 307. If the current frequency is the sterilization cell resonance frequency, the sample timing signal 307 is a signal indicating the timing at which the current should be 0, that is, the frequency signal 0 output from the PLL and timing generation circuit 323 to the PWM generation circuit 324. It is a signal which shows a cross point. The signal from the sample and hold circuit 306 is given to the frequency control unit 309 as a frequency Up / Down signal 308 which is a signal for giving an instruction to raise or lower the frequency.
[0031]
In response to the frequency Up / Down signal 308, the frequency control unit 309 generates a frequency signal 310 representing a frequency to be output for controlling the frequency of the frequency signal generated by the PLL and timing generation circuit 323. In addition, a frequency alarm signal 311 for alarming an abnormality is provided to the alarm issuing unit 320 when the frequency greatly changes to deviate from a predetermined frequency range and frequency control becomes necessary.
[0032]
On the other hand, the vibration synthesizer 332 of the sterilization cell 301 is provided with an amplitude sensor 312 that generates a signal corresponding to the amplitude of a piezoelectric element or the like, and an amplitude monitor signal 313 indicating the magnitude of the amplitude from the amplitude sensor 312. Is supplied to the amplitude detection circuit 314. As the amplitude sensor 312, an acceleration sensor is generally used, and a representative example of the amplitude sensor is a piezoelectric element. In addition, an acceleration sensor using a micromachine can also be used.
[0033]
The amplitude detection circuit 314 uses the frequency given to the vibrators 330 and 331 based on the timing signal 315 indicating the timing for evaluating the amplitude (in the embodiment of the present invention, 28 kHz is used, but generally from 10 kHz to several The amplitude monitor signal 313 from the amplitude sensor 312 alternating with the ultrasonic frequency (MHz) is detected and converted into a DC level, the magnitude of the amplitude is compared with a predetermined value, and the amplitude Up / Down indicating the magnitude of the control direction A signal 316 is generated and given to the amplitude controller 317.
[0034]
The amplitude control unit 317 corrects the amplitude signal by the amplitude Up / Down signal 316, passes the amplitude signal 318 representing the amplitude to be output to the PWM signal generation circuit 324, and deviates from the predetermined amplitude range. An amplitude warning signal 319, which is an alarm issued when control is required, is given to the alarm issuing unit 320.
[0035]
As described above, the alarm issuing unit 320 receives the frequency alarm signal 311 and the amplitude alarm signal 319 (others, such as a power supply alarm) and outputs an alarm signal to the alarm terminal 321. The signal output to the alarm terminal 321 is used for driving an alarm sound, an alarm lamp, etc., and notifies the outside of the abnormality.
[0036]
The drive circuit configured as described above performs the frequency tracking, amplitude tracking, and alarm functions of the drive frequency for the vibrator. Next, an outline of these functions will be described.
[0037]
(1) Frequency tracking
The vibrator and vibration synthesizer of the sterilization cell 301 constitute a resonator as a whole when viewed electrically, and the phase of the current with respect to the applied voltage changes around the resonance point from the equivalent circuit viewed from the drive circuit. . In the embodiment of the present invention, if the phase is in a range where the phase is a monotone function with respect to the frequency, the frequency is converged to a stable point by moving the frequency up or down by the advance or delay of the phase.
[0038]
The phase is detected by sampling the current at a phase with voltage (adjustment at the time of shipment). However, as will be described later, the current is sampled at a timing at which the resonance frequency becomes the zero cross point. As described above, the current is detected by a method using a low resistance or a transformer coupling.
[0039]
The detected current value is obtained as a voltage value, compared with the comparison voltage, the magnitude of the comparison result is stored in the D-FF, and the frequency value is calculated using an up / down counter (hereinafter referred to as UDC). I will fix it. Then, an actual frequency is realized by a PLL whose frequency ratio is a frequency division ratio.
[0040]
(2) Amplitude tracking
An amplitude sensor using an acceleration sensor such as a piezoelectric element is fixed to the resonance system by the vibrator and vibration synthesizer of the sterilization cell 301, the amplitude is observed, and the magnitude of the amplitude is compared with a fixed value (adjusted at the time of shipment). As a result, if the amplitude is large, an up / down counter (UDC) for correcting the amplitude to be small is provided, and the same control as in the frequency control is performed.
[0041]
(3) Alarm
Even if there are various abnormalities in the device, it is not necessary to issue an alarm if it is within the controllable range, and an alarm is issued if the control range is exceeded. The deviation of the control range can be detected by monitoring the overflow of the UDC at each final stage.
[0042]
Since the water treatment apparatus according to the embodiment of the present invention operates in a place where there is no person, not only a single alarm but also an alarm signal is connected between the apparatuses so that an alarm can be issued by an operator or a distribution board. ing.
[0043]
4 is a block diagram showing a detailed configuration of the frequency detection unit 328, FIG. 5 is a diagram for explaining the principle of frequency detection, and FIG. 6 is a diagram showing an equivalent circuit of the drive transformer 303. The configuration and processing operation of the frequency detection unit 328 will be described with reference to FIG. In FIG. 4, 401 is a noise removal filter, 402 is an integration circuit, and other symbols are the same as those in FIG.
[0044]
As shown in FIG. 4, the current detection unit 303 included in the frequency detection unit 328 is configured by a current detection transformer, and is between two primary windings of the drive transformer 302 that receives two signals from a driver 325 described later. It is connected. On the secondary winding side of the transformer of the current detection unit 303, a noise removal filter 401 having a differential characteristic composed of a resistor and a capacitor is provided. The embodiment of the present invention uses a signal having a frequency of 28 KHz, and the cutoff frequency of the noise removal filter 401 is set to 56 KHz. The signal after noise removal is applied to the comparator 305 via an integration circuit 402 configured by a differential amplifier and a parallel circuit of a resistor and a capacitor provided in the feedback circuit. The integration circuit 402 is for returning a signal having a differential waveform due to the differential characteristic of the noise removal filter 401. In the embodiment of the present invention, the cutoff frequency is set to 14 KHz.
[0045]
The comparator 305 compares the input voltage supplied to the integrating circuit 402 with a reference voltage that is at the ground potential, outputs a large and small binary value, and inputs it to the sample and hold circuit 306. The sample and hold circuit 306 is configured by a D-FF, and as described above, stores and holds the output from the comparator 305 at the time indicated by the sample timing signal 307, and the frequency control unit 309 stores the frequency Up / Down. The signal 308 is output.
[0046]
FIG. 5 shows the principle of frequency detection. Generally, the phase of the current with respect to the voltage changes depending on whether the applied frequency is high or low with respect to the resonance point of the vibrator. That is, at the resonance point of the vibrator, the vibrator becomes a pure resistance load when viewed from the driver, but when the frequency is shifted, it looks like L or C, and the current phase changes. Therefore, if the current is sampled at the timing when the zero cross point of the applied voltage (current is zero under this condition) in the case of a pure resistance load, the applied frequency is shifted to the higher side depending on whether the detected value is positive or negative. Therefore, the frequency signal generated by the PWM signal generator 324 can be controlled to coincide with the resonance point of the vibrator.
[0047]
As shown in FIG. 6, the equivalent circuit of the vibrator is a series circuit of a resistor R, an inductance and a capacitor, and a capacitor C connected in parallel. And the current detection transformer which comprises a current detection part is designed so that it may serve as switching current reduction inductor LC, and a drive transformer may constitute load capacity compensation inductor LT. Note that the switching current reduction inductor LC can be used also as a drive transformer, that is, the drive transformer can be used as both the switching current reduction inductor LC and the load capacitance compensation inductor LT.
[0048]
The equivalent circuit shown in FIG. 6 has both mechanical series resonance and parallel resonance due to the load capacitance and the correction inductor. Therefore, the applied frequency is shifted to the higher side depending on whether the current detection value is positive or negative, or low. In some cases, it may be reversed that it is shifted to the side, and it is necessary to confirm this. In the embodiment of the present invention, since the mechanical system Q≈20 and the compensation system Q <1, the mechanical system is dominant. However, depending on the result of confirmation, the direction of control may be reversed.
[0049]
In the embodiment of the present invention, the current to the vibrator is detected on the primary side of the drive transformer 303. The reason is that when measured on the secondary side, the measurement error is caused by the current flowing in the load capacitance and the compensation inductor. This is to avoid this and to use the current measuring transformer also as the switching current reducing inductor.
[0050]
Next, the design of the load capacitance compensation inductor LT will be described.
[0051]
Now, ω0 = 2π · 28.0 KHz. At this time, the inductance and the capacitor in series with R in FIG. 6 resonate to become 0Ω. Therefore, LT and C may be resonated. Here, the excitation inductance of the drive transformer is used as LT.
[0052]
From ω0 · LT = 1 / (ω0 · C)
LT = 1 / ((ω0) ² ・ C) (Formula 1)
The allowable deviation of LT is
± LT / √ (Q · 10) (Formula 2)
It becomes. The numerical value 10 in Equation 2 can be a small value if the driver has a margin. Note that Q = ω0 · LT / R.
[0053]
As a specific example, when C = 7900 pf and R = 37Ω, LT = 4.0 mH, allowable deviation ± 1 mH, and Q = 0.05.
[0054]
Next, the design of the switching current reducing inductor LC will be described.
[0055]
In the case of the resonance frequency of the vibrator of 28 kHz, there is no problem because the vibrator as a load appears to be a pure resistance due to compensation by LT, but LT and C do not resonate at the harmonic frequency due to switching. Appears in C. At this time, if the output voltage from the driver is switched, a large current flows through C, and the transistor constituting the driver is damaged or the power supply efficiency is deteriorated.
[0056]
For this reason, in the embodiment of the present invention, LC is inserted in series to reduce the current during switching. As a side effect due to the insertion of the LC, there is an effect that the flow of the fundamental frequency of 28 KHz is prevented, but the embodiment of the present invention is designed to suppress the loss of the fundamental frequency to about 1 dB.
[0057]
Transfer characteristic = 1 / (1 + jω0 · LC / R) (Equation 3)
Therefore, the LC with a loss of 1 dB (1 / 1.122) is
LC = √ ((1.122) ² -1) R / ω (Formula 4)
It becomes. However, this value needs to be converted to a primary value. In the case of the step-up ratio n of the driving transformer, 1 / n ² It becomes. The LC tolerance is ± 20%.
[0058]
At this time, the 7th harmonic current flowing through the driver is
R / (7ω0 · LC) (Formula 5)
It becomes the magnification of.
[0059]
To give a specific example, LC = 1.106 mH / n under the same conditions as described above. ² The ratio of the transfer characteristic to the fundamental wave of the seventh harmonic is 0.28.
[0060]
In general, the level of harmonics is smaller than that of the fundamental wave, but there are many such as 9 times and 11 times. For this reason, if the power efficiency and transistor ratings are comprehensively examined and the load becomes a big problem, instead of increasing the LC value, a capacitor is inserted in series to pass the fundamental wave, that is, The resonance between the LC and the capacitor to be inserted is made to resonate at the center frequency, and the impedance between the LC and the capacitor to be inserted can be made zero at the center frequency.
[0061]
FIG. 7 is a block diagram showing a detailed configuration of the amplitude detection circuit 314. Next, the configuration and processing operation of the amplitude detection circuit 314 will be described with reference to FIG. In FIG. 7, 701 is an equalizer circuit, 702 is a detection circuit, 703 is an LPF (low-pass filter), 704 is a comparator, 705 is a D-FF, and other symbols are the same as those in FIG.
[0062]
The amplitude detection circuit that receives the amplitude monitor signal 316 that is the detection signal from the amplitude sensor 312 and generates the amplitude Up / Down signal 316 includes an equalizer circuit 701 for the detection signal from the amplitude sensor 312 as shown in FIG. The detection section for detecting the output from the equalizer circuit 701, the LPF 703, the comparator 704 for comparing the output from the LPF 703 and the reference voltage and outputting the result, and the amplitude sample timing signal 315 from the PLL and timing generation circuit 323 The D-FF 705 captures and holds the output from the comparator 704 and outputs it as an amplitude Up / Down signal 316.
[0063]
In the above description, the equalizer circuit 701 is adjusted at the time of manufacture so that the gain can obtain a specified mechanical amplitude, and has a function of compensating the frequency characteristic of the amplitude sensor and a function of removing noise. In addition, when the amplitude sensor 312 is configured by a sensor that detects acceleration, the equalizer circuit 701 is a signal that is proportional to the amplitude by integrating twice around the 28 kHz frequency that is used in the embodiment of the present invention. It also has the function.
[0064]
The output signal from the equalizer circuit 701 is converted into a DC voltage indicating the magnitude of the amplitude detected via the detection circuit 702 and the LPF 703 and applied to the comparator 704. The comparator 704 compares the DC voltage indicating the magnitude of the amplitude input via the LPF 703 and the reference voltage, and outputs a binary signal indicating which is larger to the D-FF 705. The LPF 703 needs to sufficiently reduce the 28 KHz component, and if the response speed is too slow, the control loop of about 1 second becomes unstable, and thus a response speed that is relatively fast is required. Therefore, the cutoff frequency of the LPF 703 is set to about 280 Hz.
[0065]
FIG. 8 is a block diagram showing detailed configurations of the frequency control unit 309, the amplitude control unit 317, the PLL, the timing generation circuit 323, and the PWM signal generation 324. Next, with reference to FIG. The circuit configuration and processing operation will be described. In FIG. 8, 801 to 804 are Up / Down counters, 805 is a PLL clock circuit, 806 is a timing generation circuit, 807 is a 10-bit counter, 808 and 809 are 10-bit adders, 810 and 811 are coincidence detection circuits, 812, Reference numeral 813 denotes a pulse generator, and other reference numerals are the same as those in FIG.
[0066]
First, the frequency control unit 309, the PLL, and the timing generation circuit 323 will be described. The frequency control unit 309 includes two Up / Down counters 801 and 802 and is controlled by a frequency Up / Down signal 308 from the frequency detection unit 328. The Up / Down signal 308 is input at a frequency of 28 kHz. The frequency control range in the frequency control unit 309 is F1 Hz to F2 Hz. This width needs to cover the resonance frequency deviation of the mechanical system, and at the same time, the mechanical system does not cause vibration in another mode. It is also necessary to be narrow. Further, the control by the frequency control unit 309 needs to be performed earlier than the amplitude control in order to prevent an inrush current by the amplitude control. In the embodiment of the present invention, the amplitude control is 1 second and the frequency control is 0.1 second. These ratios are set to be at least 10 so that the control and the frequency control do not interfere with each other.
[0067]
The Up / Down counter (F2) 802 preferably has a frequency resolution of 100 Hz or less from a frequency resolution <28 kHz / (10 · Q), and is designed to obtain a resolution of about 50 Hz. The frequency variable range is ± 1 kHz with respect to the center frequency of 28 kHz. As a result, the maximum value NF1, minimum value NF2, and center value NF of the frequency signal 310 as a control signal for the PLL output from the Up / Down counter (F2) 802 and the timing generation circuit 323 are:
NF1 = maximum frequency / resolution = 29 kHz / 50 Hz = 580
NF2 = Minimum frequency / Resolution = 27 kHz / 50 Hz = 540
NF = 28 kHz / 50 = 560 (the initial value at the time of resetting), and therefore, the Up / Down counter (F2) 802 requires 10 bits.
[0068]
When the counter sum overflows, the Up / Down counter (F2) 802 transmits an alarm to the alarm issuing unit 320 on the assumption that the frequency has not converged.
[0069]
Up / Down counter (F1) 801 is a random walk filter that eliminates the effects of trivial noise and determines whether the average value is 1 or 0. The frequency immediately after the startup of the device is clear If it is deviated, the received Up / Down signal is counted, and when it overflows, the counter (F2) is controlled for up / down for the first time.
[0070]
The number of Up / Down signals 308 received during the frequency tracking time of 0.1 seconds is 28 kHz × 0.1 seconds = 2800 times. In order to change the value of the counter F2 from the minimum to the maximum with this number, the overflow count number KF of the counter F1 is:
From 28KHz × 0.1sec / KF = NF1-NF2,
KF = 28 KHz × O. 1 second / (NF1-NF2) = 70.
[0071]
The PLL / timing generation circuit 323 includes a PLL clock circuit 805 and a timing generation circuit 806. The PLL clock circuit 805 outputs the clock of the frequency F0 from the clock source 322 as NF / K times using the frequency signal NF from the Up / Down counter (F2) 802. Here, F0 and K are determined by design. Since the timing generation circuit 806 generates F1 = 28 kHz × 1024 = 28.672 MHz and several phases, the frequency may be doubled depending on the design at the time of implementation.
[0072]
Next, the amplitude control unit 317 will be described. The amplitude control unit 317 includes two Up / Down counters 803 and 804, and is controlled by an amplitude Up / Down signal 316 from the amplitude detection circuit 314. The Up / Down signal 316 is input at a frequency of 28 kHz. The range of the amplitude control numerical value NA in the amplitude control unit 317 is 0 to 511, and as already described, the amplitude control is slower than the frequency control and is 1 second.
[0073]
The Up / Down counter (A1) 803 is a filter that eliminates the influence of trivial noise as a random walk filter and determines whether the average value is 1 or 0. When starting from, the up / down signal to be received is counted, and when it overflows, the counter (A2) is controlled for up / down for the first time.
[0074]
The number of Up / Down signals 308 received during one second of the amplitude following time is 28 kHz × 1 second = 28000 times. In order to change the value of the counter A2 from the minimum to the maximum with this number, the overflow count number KA of the counter A1 is:
From 28KHz × 1sec / KA = 511,
KA = 28 kHz × 1 second / 511 = 55.
[0075]
Then, when an overflow occurs, the Up / Down counter (A2) 804 transmits an alarm to the alarm issuing unit 320 because the amplitude is insufficient.
[0076]
Next, the PWM signal generation circuit 324 will be described. As shown in FIG. 8, the PWM signal generation circuit 324 includes a 10-bit counter 807, two 10-bit adders 808 and 809, two coincidence detection circuits 810 and 811, two pulse generators 812, 813 is configured to generate a pair of PWM signals.
[0077]
The PWM signal generation circuit 324 used in the embodiment of the present invention is configured to be able to perform amplitude control. First, the PWM signal waveform used in the PWM signal generation circuit 324 and the amplitude control method are described. Control.
[0078]
FIG. 9 is a diagram showing a PWM signal waveform used in the PWM signal generation circuit 324 in the embodiment of the present invention, and FIG. 10 is a diagram for explaining an amplitude control method.
[0079]
In the embodiment of the present invention, the output signal of the PWM signal generation circuit 324 is amplified by a driver 325 using a class D amplifier. At that time, in order to increase the power efficiency using the class D amplifier, it is necessary to suppress the multi-mode vibration of the mechanical system due to the harmonics. Therefore, the embodiment of the present invention uses a PWM signal having a waveform as shown in FIG. Since the waveform shown in FIG. 9 does not include the second to sixth harmonics, multimode vibration of the mechanical system can be suppressed. In the embodiment of the present invention, the waveform shape and size shown in FIG. 9 are output from the PWM signal generation circuit 324 without being changed.
[0080]
In general, the amplitude can be adjusted by the power supply voltage of the class D amplifier. However, the amplitude can be controlled by changing the phase of the waveform applied to both ends of the drive transformer without using such a variable voltage power supply. The embodiment of the present invention is based on such a concept. As described above, the PWM signal generation circuit 324 generates a pair of PWM signals. If it is not necessary to care about the output phase, only one signal of the drive transformer may be changed. However, in the embodiment of the present invention, frequency control is performed by phase detection. It is necessary to maintain the phase.
[0081]
The fact that the amplitude can be controlled by changing the phase of the waveform applied to both ends of the drive transformer will be described with reference to FIG.
[0082]
When the two signals applied to the driving transformer have the same phase, as shown in FIG. 10A, the potential difference between both ends of the transformer becomes 0, and therefore the output becomes 0. Further, when there is a phase difference between the two signals, as shown in FIG. 10B, a potential difference is generated between both ends of the transformer, and an output by a cos component is obtained as an output. Further, when the two signals are in opposite phases, as shown in FIG. 10C, the potential difference between both ends of the transformer is doubled, and the cos component as the output is maximized. In the amplitude control as described above, if the phase of two signals is changed symmetrically in both positive and negative directions from the same phase, only the magnitude of the amplitude is controlled without changing the output phase at all. be able to.
[0083]
FIG. 11 is a diagram showing a numerical value output from the 10-bit counter 807 of the PWM signal generation circuit 324 and waveforms output from the two pulse generators 812 and 813, and FIG. 12 explains the relationship between the control numerical value NA and the amplitude. FIG.
[0084]
In the configuration of the PWM signal generation circuit 324 described above, the numerical value T output from the 10-bit counter 807 has a sawtooth waveform as shown in FIG. The adders 808 and 809 receive the amplitude signal NA for controlling the amplitude from the amplitude control unit 318, and calculate 512-NA and 512 + NA, respectively. The coincidence detection circuits 810 and 811 cause the pulse generators 812 and 813 to start and generate a sine wave at the timing when the sawtooth waveform from the 10-bit counter 807 coincides with 512-NA and 512 + NA. Give instructions. The pulse generators 812 and 813 output a pair of PWM signals having mutually symmetrical phase changes according to the amplitude to be output. Thus, the PWM signal generation circuit 324 can output a pair of PWM signals that can control the amplitude of the signal output via the drive transformer without changing the output phase.
[0085]
The relationship between the numerical value NA of the amplitude signal and the output amplitude is not linear, and is a sin curve as shown in FIG. From the viewpoint of automatic control, a linear characteristic that does not change the eigenvalue is preferable, but there is no problem because the response becomes gradual.
[0086]
FIG. 13 is a block diagram showing the configuration of the driver 325. In FIG. 13, reference numerals 131 to 134 denote logic voltage-FET drive signal conversion circuits, reference numerals 135 to 138 denote output FETs, and other reference numerals are the same as those in FIG.
[0087]
As shown in FIG. 13, the driver 325 including a class D amplifier includes four logic voltage-FET drive signal conversion circuits 131 to 134 and four output FETs 135 to 138 connected to these circuits. Is done. The logic voltage-FET drive signal conversion circuits 131 and 132 are connected to one output of the PWM signal generation circuit 324 described above, and the logic voltage-FET drive signal conversion circuits 133 and 134 generate PWM signals. The other output of the circuit 324 is connected. Further, the logic voltage-FET drive signal conversion circuits 131, 133 turn on the FETs 135, 137 at the logic signal H level, and the logic voltage-FET drive signal conversion circuits 132, 134 at the logic signal L level. Signal conversion is performed so that the FETs 136 and 138 are turned on. Further, the FETs 135 and 136 are connected in series and a voltage of 150 V and 0 V is applied to both ends, and the FETs 137 and 138 are connected in series and a voltage of 150 V and 0 V is applied to both ends.
[0088]
The driver 325 configured as described above can be designed by diverting the driver for a reliable and proven sonar. The difference between the driver used in the embodiment of the present invention and that for sonar is that the load is different, the operating frequency is different, the continuous operation must be performed, so heat dissipation etc. should be considered, and the heat from the hot water This is a point to consider for temperature rise.
[0089]
Next, issuing an alarm in the embodiment of the present invention will be described. In the above description, the frequency abnormality and the amplitude abnormality have been described, but the issue of an alarm including these abnormalities will be described.
[0090]
When power is off
Pilot lamp does not light up. It is unused and does not issue a warning. If there is a customer who wants to issue an alarm when the power is turned off, it can be dealt with by a design change, for example, using a normal ON type relay.
[0091]
At the time of electric leakage
The power is cut off due to the operation of the earth leakage breaker. This can be expressed by the earth leakage display of the earth leakage breaker and the extinction of the pilot lamp. No alarm is issued by electric signal. If there is a customer who wants to issue an alarm due to the leakage breaker breaking, it can be dealt with by design change, and it can be dealt with by using a normal ON type relay as described above.
[0092]
Frequency abnormality
When the resonance point changes outside the specified frequency range due to erosion, loosening, piezoelectric element destruction, leakage, etc., an alarm is issued from the alarm lamp and alarm terminal.
[0093]
Amplitude abnormality
When changing outside the specified amplitude range due to erosion, loosening, piezoelectric element destruction, leakage, etc., an alarm is issued from the alarm lamp and alarm terminal.
[0094]
Alarm operation check
At each power-on, an alarm is issued to the alarm lamp and alarm terminal for 1 second.
[0095]
Alarm terminal specifications
Equipped with relay contact 3 terminals, an ON alarm set, and an OFF alarm set. The capacity of the voltage / current is set to AC 100 V, 1 A (capacity capable of lighting a light bulb).
[0096]
Maintenance operation method during alarm
In the embodiment of the present invention, the alarm signal is connected to the outside of the apparatus in parallel (ON alarm) or in series (OFF alarm) to sound or light the distribution panel or the maintenance device alarm device. The maintenance person can rush to the location of the device and identify an abnormal device by looking at an alarm lamp provided for each device. In addition, since a large number of sterilization cells are operated in parallel, the overall sterilization rate does not become zero even if one sterilization cell is stopped.
[0097]
A maintenance person such as a manufacturer may bypass the water by operating the valve, remove or replace the abnormal device, and then return the valve to its original state. Replacement after repair can be performed in the same way. The diverter and merger must be able to be plugged so that water does not leak even when the sterilization cell is removed, so that some of the sterilization cells can be repaired. Even if it is removed, the system can continue to operate with the remaining sterilization cells.
[0098]
The above-described embodiment of the present invention has been described on the assumption that control is performed by a digital circuit such as an FPGA. However, the present invention can perform an equivalent process using an inexpensive CPU, and an analog circuit. It is also possible to perform an equivalent process by.
[0099]
Although the present invention described above has been described with reference to an example of use for sterilization of circulating bath water for hot spring water, the present invention is also used for treatment of tap water, sludge treated water, and tanker ballast water. Furthermore, it can be applied to automatic frequency / amplitude control and alarm detection of ultrasonic processing machines (processing tools, medical ultrasonic scalpels, wire bonders, melted adhesive heaters).
[0100]
【The invention's effect】
As described above, according to the present invention, it is possible to perform automatic tracking and automatic amplitude control with respect to the ultrasonic frequency so that optimum cavitation occurs, and the resonance frequency changes due to the device itself being shaved. When the operating range is exceeded, an abnormality such as when there is no water can be notified, and an alarm can be issued when either the frequency or the amplitude deviates from the tracking range.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a system configuration when a water treatment apparatus according to an embodiment of the present invention is used for sterilization of a circulating bath.
2 is a diagram showing a configuration of a piping system in FIG. 1. FIG.
FIG. 3 is a block diagram showing a configuration of a water treatment device according to an embodiment of the present invention.
FIG. 4 is a block diagram showing a detailed configuration of a frequency detection unit.
FIG. 5 is a diagram illustrating the principle of frequency detection.
FIG. 6 is a diagram showing an equivalent circuit of a drive transformer.
FIG. 7 is a block diagram showing a detailed configuration of an amplitude detection circuit.
FIG. 8 is a block diagram showing a detailed configuration of a frequency control unit, an amplitude control unit, a PLL, a timing generation circuit, and a PWM signal generation.
FIG. 9 is a diagram illustrating a PWM signal waveform used in the PWM signal generation circuit according to the embodiment of the present invention.
FIG. 10 is a diagram illustrating an amplitude control method.
FIG. 11 is a diagram illustrating a situation of numerical values output from a 10-bit counter of a PWM signal generation circuit and waveforms output from two pulse generators.
FIG. 12 is a diagram for explaining a relationship between a control numerical value NA and an amplitude.
FIG. 13 is a block diagram illustrating a configuration of a driver.
[Explanation of symbols]
101 bathtub
102 Chlorine source
103 hair collector
104 pump
105 Filter
106 Piping system
107 Wiring system
108 Piping pipe
109-111 valve
112 shunt
113 Merger
114 Water treatment equipment
115 Heater
116 Yuan breaker
117 Alarm display device
201 Rainproof power terminal
202 Earth leakage breaker and power switch (SW)
203 Pilot lamp
204 Alarm lamp
205 Earth, alarm terminal
206 Bolt clamp
207 faucet
301 Sterilization cell
302 Drive transformer
303 Current detector
305 Comparator
306 Sample and hold circuit
309 Frequency control unit
312 Amplitude sensor
314 Amplitude detection circuit
317 Amplitude control unit
320 Alarm issuing section
321 Alarm terminal
322 clock source
323 PLL, timing generation circuit
324 PWM signal generation circuit
325 driver
326 Power circuit
327 Earth terminal
328 Frequency detector
330, 331 vibrator
332 Vibration Synthesizer
333 cylindrical container
334 Sterilization cylinder

Claims (8)

In a water treatment method for sterilizing bacteria in water by driving and controlling a vibrator of a sterilization cell and applying ultrasonic vibration to water to be treated, the amplitude of the vibrator is detected and the frequency of a signal applied to the vibrator , And based on the detected amplitude of the vibrator and the frequency of the detected signal, the amplitude and vibration frequency of the vibrator are controlled to become target values, and the amplitude of the vibrator at that time The amplitude is controlled without changing the phase of the vibration by applying a pair of PWM signals having phase changes symmetrical to each other to the vibrator through the drive transformer according to the magnitude of the amplitude. The water treatment method characterized by performing to.   2. The water treatment method according to claim 1, wherein the vibration frequency of the target vibrator is a resonance frequency of a vibration system including the vibrator that varies depending on the influence of water temperature, flow velocity, impurities, and the occurrence of cavitation. .   The water treatment method according to claim 1 or 2, wherein the frequency of the signal applied to the vibrator is detected by detecting a phase of a current with respect to a voltage of the signal applied to the vibrator. The water treatment method according to claim 1, 2, or 3, wherein an alarm is issued when an abnormal magnitude is detected in the amplitude and vibration frequency of the vibrator . In a water treatment apparatus that drives and controls a vibrator of a sterilization cell and sterilizes bacteria in water by applying ultrasonic vibration to water to be treated, means for detecting the amplitude of the vibrator, and a signal applied to the vibrator A means for detecting a frequency, a control means for controlling the amplitude of the vibrator to be a target value based on the detected amplitude of the vibrator, and a frequency of the vibrator based on the frequency of the detected signal. Control means for controlling the vibration frequency to be a target value, and the amplitude control means of the vibrator generates a pair of PWM signals having phase changes symmetrical to each other according to the magnitude of the amplitude. A water treatment apparatus comprising: a PWM signal generating means; and a drive transformer that synthesizes the pair of PWM signals and applies them to the vibrator. 6. The water treatment apparatus according to claim 5, wherein the target vibration frequency of the vibrator is a resonance frequency of a vibration system including a vibrator that varies depending on the influence of water temperature, flow velocity, impurities, and the occurrence of cavitation. . 7. The water according to claim 5, wherein the means for detecting the frequency of the signal applied to the vibrator comprises means for detecting the phase of the current with respect to the voltage of the signal applied to the vibrator. Processing equipment. The water treatment apparatus according to claim 5, 6 or 7, further comprising means for issuing an alarm when an abnormal magnitude is detected in the amplitude and vibration frequency of the vibrator .

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