JPS5959278A - Ultrasonic washing machine - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ultrasonic cleaner that automatically adjusts to conditions such as the amount of water in a cleaning tank and cleans at a frequency that maximizes cleaning energy.

FIG. 1 shows an example of the configuration of a conventional ultrasonic cleaning machine. In the figure,
1 is a cleaning tank, 2 is water, 3 is a vibrating section consisting of a plurality of electrostrictive vibrators, 4 is a high frequency oscillator, 5 is a power amplifier, and 6 is a transformer. When the user puts dishes and the like into the washing water in the washing 4'1i1 and turns on a lightning source (not shown), the high frequency oscillator 4 oscillates and sends high frequency waves to the power amplifier 5. The power amplifier 5 amplifies the power of the input high frequency wave and sends it to the vibrating section 3 via the transformer 6. The vibrating part 3 is driven by high frequency power,
Ultrasonic energy is supplied into the cleaning tank 1. Water 2 causes cavitation due to ultrasonic energy and washes items immersed in water, such as tableware.

Figure 2 is an explanatory diagram of the resonant frequency of the vibrating part 3, where the horizontal axis represents the frequency and the vertical axis represents the admittance of the vibrating part B.
The correspondence between frequency and admittance is shown when the fundamental resonance frequency is 24Hz and the water level (height from the top surface of the vibrating part to the water surface) is 135 mm. The frequency corresponding to the maximum admittance value is the resonant frequency, and there are two resonant frequencies, marked with ○ and marked with . However, the one marked with 0 has a higher admittance and better matching is obtained. In addition, both the O mark and the - mark deviate from the basic resonance frequency, but this is due to the shape of the cleaning tank 1, water volume, water temperature, and installation of the vibrating part due to the law, etc. For example, it is further influenced by its material, shape, location, etc.

Figure 3 shows the correspondence between the water level on the horizontal axis and the resonance frequency on the vertical axis. The O mark is the point where the admittance is maximum, as in the t42 diagram, and the * mark is the resonance point other than the O mark ( As can be seen from Figure 0, which is the frequency corresponding to the maximum admittance value, when the water level changes, the position (frequency) and number of resonance points change, and the position of the resonance point marked with a circle changes.

Therefore, if the vibrating section is driven at a fixed single frequency as in the conventional example shown in FIG. 1, proper matching cannot be achieved and efficiency is poor.

Conventionally, as a countermeasure to this problem, there have been examples of manually changing the frequency of the high-frequency oscillator, but this had the disadvantage of being inconvenient to use. If the imaging unit 3 is a self-oscillation method in which it is part of a high-frequency oscillator, stable oscillation cannot be achieved due to the pull-in phenomenon.
The disadvantage is that in some cases, oscillation almost stops.

The automatic tracking method, in which a detection part is installed in the vibrating part B, detects changes in the resonant frequency, performs phase correction, and sends feedback to the high-frequency oscillation part can drive the vibrating part stably at the resonant frequency. As shown in FIGS. 2 and 3, since there are multiple resonance points, an ultrasonic cleaner in which the neck of the appropriate resonance frequency varies greatly was not sufficiently effective. In other words, if you select a certain resonance frequency and start operation, it will follow the change in the resonance point (frequency), but this selected frequency range will not necessarily give the maximum admittance even if it gives the maximum admittance. This is because it is not a thing.

Next, FIG. 4 shows a free admittance diagram of the imaging section 3 in FIG. 1. In the diagram, a thick circle indicates that there is no water in the cleaning tank 1 (
(air only), the small circle is the case when the cleaning tank 1 is filled with water 2. As shown in the figure, when there is no water in the cleaning tank, the admittance is very large, and if the vibrating section 3 is driven in this state, a large current will flow and the vibrating section 6 will be damaged.

As a countermeasure to this, we installed a float switch.

Some attempts were made to insert a current limiting circuit breaker into the power supply, but there were problems such as an increase in size and price.

An object of the present invention is to drive the vibrating section at a frequency that automatically always brings the optimum matching state without the various problems mentioned above, and to drive the vibrating section at a frequency that automatically always brings the optimum matching state, and to An object of the present invention is to provide an ultrasonic cleaner that prevents damage by stopping the drive of the ultrasonic cleaner.

In order to achieve the above object, the present invention provides.

By sweeping the frequency that drives the vibrating part, the optimal frequency that can supply the maximum amount of ultrasonic energy to the cleaning tank that houses the load containing the object to be cleaned in the cleaning liquid is detected and stored, and the frequency that drives the vibrating part is detected and stored in advance. A mechanism is installed to drive the vibrating part for a set period of time to automatically always obtain the maximum cleaning power.On the other hand, as the drive frequency is swept, the current flowing through the vibrating part reaches a preset large value. If this is detected, a mechanism is installed that determines that there is no load and stops the drive of the vibrating section to prevent damage. As shown in FIG. 4, the difference in admittance under load and under no load is on a completely different order of magnitude, so it is easy to determine no load.

Hereinafter, the present invention will be explained in more detail with reference to the drawings. FIG. 5 is a block diagram of one embodiment of the present invention.

In the figure, the same reference numerals as in FIG. 1 refer to the same things.

13 is a triangular wave generating circuit that generates a triangular wave voltage VF1 when the input to its reset input section RES is at a low level; 14;
is a clock generation circuit that generates a falling clock Vc at the falling portion of the voltage "Fl." Specifically, both of these circuits include a constant current circuit having a switch, and a constant current circuit that is charged by the output current of this circuit. It consists of a circuit including a capacitor and a PUT (programmable unijunction transistor) to which the charge mW voltage of this capacitor is applied to the anode and a reference voltage is applied to the gate.

16 is a one-shot multi (timer) circuit operated by the clock VCK and outputs the voltage VSr; 15 is a one-shot multi (timer) circuit that stores the voltage VF1 when the input of the reset input section RES is at a low level and the input of the set input section SET is at a high level; A sample (peak) hold circuit outputs a storage voltage VF2. Reference numeral 11 denotes a multiplexer which selects VFl when the input of the set input section SET is at a low level, and selects VR2 when the input is at a high level, and outputs the selected voltage as a voltage V. Reference numeral 7 denotes a VCO (voltage controlled oscillator) that oscillates at a frequency fr depending on the voltage V when the input to the reset input section RES is at a low level. 8 is an AGC (automatic gain control circuit) that controls the output voltage vo of the stain force amplifier 5 by inputting the voltage vB corresponding to the secondary side voltage of the transformer 6 to the feedback voltage input section FB; A voltage of fv is supplied to a power amplifier 5, and from this amplifier, frequency fy, voltage vo, i! The power of stream 11) is outputted to the transformer 6, and the transformer 6 draws pressure and supplies the power to the vibrating part B to generate ultrasonic energy. 9 is a current detection unit that detects current and LO; 10 is a current detection unit 9
An amplifier that rectifies the output of and amplifies the DC voltage V, which outputs a DC voltage V corresponding to the current to. 12 is the reset input section R
Detects the maximum value of voltage V when the ES input is low level!
2. A peak detector circuit which sets the output voltage VST to a high level during detection and outputs it to the set input section SET of the sample (peak) hold circuit 15. 18 is a constant voltage V
17 is a reference voltage generation circuit that outputs voltage V, and V
R and compare the voltage VCP to the reset input R of VCO7.
A comparator that outputs to ES sets VCP to a low level when Vtt>Vr, and raises and holds Vc to a high level when VI≧V. That is, the comparator 17 is of a self-holding type and maintains a high level until the power is cut off. Note that the output VsrFi of the one-shot multi (timer) circuit 16 remains in a low level state until the clock VCK is input.
When K is input, it becomes high level for a preset time, and the reset input section RAS of the triangular wave generation circuit 13, the set input section SET of the multiplexer 11,
This is the voltage supplied to the reset input RES of the sample (peak) hold circuit 15 and the reset input RES of the peak detector circuit 12.

FIG. 6 is a time chart of the operation of each part of the embodiment shown in FIG. Now, when the user fills water 2 into the washing tank 1, submerges dishes or other objects to be washed, and turns on the washing machine, the voltage VF1 of the triangular wave generation circuit 13 increases. At this time, since the output voltage VCK of the clock generation circuit 14 is at a high level, the one-shot multi (timer) circuit 16
The output voltage VSm- of is in a low level state. Therefore, the multiplexer 11 outputs the output voltage VF1 of the triangular wave generating circuit 1.
is selected and this voltage is sent to the VCO 7 as an output voltage 77. The VCO7 oscillates at a constant frequency fV due to the voltage V, that is, VFl, and the voltage at the frequency of this fv is
Send to GC8. In addition, as shown in FIG. 6 (8), fr increases with a gradually increasing slope from 21 kHz to 27 kHz in contrast to the rise in FIG. While receiving the feedback of the voltage νB, a voltage with a frequency f is supplied to the power amplifier 5, and its output voltage U□ is controlled.The power amplifier 5, while being controlled by Aα゛8, supplies a voltage Uo with a frequency fr and a current to The transformer 6 outputs the voltage U according to the secondary voltage.
B is sent to the AGCs, and the voltage vo is boosted and sent to the vibrating section 3. The vibrating section 3 is driven by high frequency power (voltage) from the transformer 6 and supplies ultrasonic energy into the cleaning tank 1 . The water 2 is vibrated by ultrasonic energy and washes objects such as tableware. On the other hand, the current detection section 9 detects the output current L□ of the current amplifier 5 and sends a signal to the amplifier 10. The amplifier 10 rectifies the output of the current detection section 9, amplifies the direct current, and sends the output voltage V to the peak detector circuit 12. Here, the voltage V changes, for example, as shown in FIG. 6(4)K while the triangular wave voltage VF1 is rising, that is, while the frequency fv is rising.

Since this change in voltage UI is similar to the change in admittance of the vibrating section 3, its maximum value becomes the optimal resonance point when matching is achieved. The peak detector circuit 12 is shown in FIG.
6), the voltage V! input to the reset input section RAS! ; Since W is at a low level, when voltage V increases, output voltage VsT is set at high level and sampled (peak)
It is output to the set input section SET of the hold circuit 15. In the illustrated case, from t km to t4-1 and from t km t1 to t6
reaches a high level. Since the input voltage VSF of the reset input section RES is at a low level, the sample (peak) hold circuit 15 stores the voltage VF1 when the input voltage VST of the set input section SET is at a high level. Therefore, in FIG. 6 (6), VFl at the last time t,
That is, rshi2 is stored. The frequency fr of the VCO 7 at this time becomes fr6 in FIG. 6(8). Note that the output voltage V of the amplifier 10 is sent to one input of a comparator 17, and the comparator 17 compares the output voltage VR of the reference voltage generation circuit 18 with V.

Since the maximum value VIM is lower than VR, the output voltage VCP is kept at a low level. Therefore, the VCU 7 performs the above operation. Eventually, at time t or t, the output voltage VF of the triangular wave generation circuit 13 falls by 1, and the clock generation circuit 1
4 is the clock "cr t one shot multi (timer)
to circuit 16, which raises the output voltage VSII' to a high level. As a result, the multiplexer 11 selects the output voltage VF2 of the sample (peak) hold circuit 15. VFl at this time is the above-mentioned V;2, which is a voltage that provides the optimum resonance point (frequency) when matching is achieved. Konori=V! The voltage of 2 is sent to the VCO 7, and the VCU 7 oscillates at a frequency fr6. As a result, the vibrating section 3 is driven at a well-matched resonant frequency fr6, and the objects to be cleaned, such as tableware, are efficiently cleaned using large amounts of ultrasonic energy manually. Note that at this time, since the output voltage VSIF of the one-shot multi (timer) circuit 16 is at a high level, the triangular wave generation circuit 13 and the peak detector circuit 12 maintain their output voltages V/1 and rSr at a low level. . Further, when a preset time has elapsed from time 1°, the one-shot multi (timer) circuit 16 lowers the output VsF to a low level. Therefore, the triangular wave voltage VF1 starts rising again. There is a slight difference between the time t when the voltage Vsr falls and the time t when VFl starts rising for the second time.
The sample (peak) hold circuit 15 uses this time 1. −
1. The voltage memorized between V! Sweep the frequency fV applied to the vibrating part such that 0 or higher makes 2 a low level, detect the optimum frequency h6, and memorize fy6 (actually, VC
It is possible to drive the vibrating unit 3 for the time preset with L and fy6 (memorize the voltage VF2 applied to O7), that is, the time from t:tl to tt4, and as a result, cleaning is performed with optimal matching. It can be performed. It is preferable that the time required for the sweep is sufficiently shorter than the preset time, and in this embodiment, the period from t=0 to t is 0.6 seconds.

1=1. We assigned 10 seconds from t to t.

Next, the operation when the power is turned on in a no-load state with no cleaning liquid or the like in the cleaning tank will be explained with reference to the time chart shown in FIG. Now, if the user turns on the power to the washing machine in a no-load state, the triangular wave generation circuit 13
The output voltage VF1 of the clock generation circuit 14, the output voltage VF1 of the clock generation circuit 14
cJC, the output voltage VSF of the one-shot multi (timer) circuit 16 is the same as in the case of FIG. 6 fl) -f, 91, as shown in FIGS. 7 (1) to (3). Similarly, the output voltage V of the multiplexer 11 is also the voltage VF1 and VF1.
The output voltage VR of the reference voltage generation circuit 18 is
The same is true. However, as the voltage VF1 rises and the frequency of the vibrating section 3 approaches the fundamental resonant frequency, the amplifier 10
The output voltage V increases exponentially. Eventually, when VR≦V at time tB, the output voltage VCP of the comparator 17 changes from a low level to a high level and self-holds at the high level. Therefore, the input of the reset input section RES of VCU 7 becomes high level, stopping oscillation, and f
y=oBz. Therefore, the output current L of the power amplifier 5
o stops flowing, and the output voltage V of the amplifier 10 also becomes low level. If the oscillation frequency fy of the VCO 7 is increased to the fundamental resonance frequency without stopping the oscillation (by removing the comparator 17 or cutting off the reset input to the VCO 7, etc.), Fig. As shown, the circle of free admittance of the vibrating section 3 is very large, and the value of the current to is extremely large, which may damage the vibrating section 3. 7th
V'I shown by the broken line in Figure Q is drawn assuming that the oscillation of the VCO 7 is not stopped. In this way, in the present invention, when the value of V, which changes according to t□, reaches the preset reference voltage value VR, it is determined that there is no load and the oscillation of the VCO 7 is stopped.
However, instead of io, the current flowing through the vibrating section 3 may be directly detected by the voltage across a resistor inserted in series with the circuit.

As explained above, according to the present invention, it is possible to automatically select the optimum vibration frequency for the load and perform cleaning efficiently at all times.
There is no problem even if you change the water level or change the shape or placement of the object to be cleaned due to the low level of uneven cleaning.Furthermore, even if you turn on the power with no load without adding cleaning liquid, it will not be damaged. I don't need it.

[Brief explanation of the drawing]

Figure 1 is an example diagram of a conventional ultrasonic cleaning machine, Figure 2 is a characteristic diagram showing the correspondence between admittance and frequency of the vibrating part on the same side, and Figure 3 is a diagram showing the correspondence between resonance frequency and water level on the same side. Fig. 4 is a diagram showing the free admittance of the vibrating part in comparison with the case where water is added as a load, Fig. 5 is a configuration diagram of an embodiment of the present invention, and Fig. 6 is a diagram of the same embodiment. FIG. 7 is a time chart for normal operation when the power is turned on with no load in the same embodiment. 5... Shake! jb section 7...VCU (pressure controlled oscillator) 8...AGC (automatic gain control circuit) 9...current detection section 10...amplifier 11...
・Multiplexer 12...Peach lid circuit 15...Triangular wave generation circuit 14...Clock generation circuit 15...Sample (peak) hold circuit 16・
・・Multi (timer) circuit 17 ・Comparator 18 ・Reference voltage generation circuit Fig. 1 Fig. 2

Claims (1)

[Scope of Claims] +11 In an ultrasonic cleaning machine that cleans an object by supplying ultrasonic energy generated by a vibrating part to a cleaning tank containing a load in which an object to be cleaned is immersed in a cleaning liquid, An ultrasonic cleaning machine comprising a mechanism that sweeps the frequency applied to the vibrating part, detects and stores the optimal frequency for power matching, and drives the vibrating part for a preset time using the stored frequency. . (2) In an ultrasonic cleaning machine that cleans the object by supplying ultrasonic energy generated by a vibrating section to a cleaning tank containing a load in which the object to be cleaned is immersed in a cleaning liquid, the ultrasonic energy is applied to the vibrating section. The present invention is characterized by having a mechanism that sweeps the frequency and, when it is detected that the current value flowing through the vibrating part reaches a preset value t7, determines that there is no load and stops the driving of the vibrating part. Ultrasonic cleaning machine.