JPS6128386B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ultrasonic cleaner that installs an ultrasonic vibrator in a cleaning tank and performs cleaning by emitting ultrasonic waves into the cleaning liquid, and operates even when there is no cleaning liquid in the cleaning tank. This prevents the vibrator from being destroyed. The purpose of this invention is to provide a so-called dry firing prevention circuit.

First, a conventional ultrasonic cleaner of this type will be explained with reference to FIGS. 1 to 4.

FIG. 1 is a circuit diagram of a conventional ultrasonic cleaner.
E _AC is an AC input power supply voltage, diodes D ₁ to _{D 4} are a double-wave rectifier circuit of E _AC , C ₁ is a noise prevention capacitor, and the following circuits constitute an oscillation circuit. In addition, X
is an ultrasonic vibrator such as a piezoelectric element, and _T1 is an oscillation transformer. FIG. 2 shows the waveforms of the rectified voltage E ₁ and the current i _x flowing through the vibrator X.

FIG. 3 shows a diagram in which an ultrasonic transducer 2 (indicated by X in the schematic diagram of FIG. 1) is attached to the cleaning tank 1. Note that 3 is a cleaning liquid such as water.

Figure 4 shows the temperature rise curve of the cleaning tank after the power is turned on. 4 is a case in which a cleaning liquid is present, and the emitted ultrasonic waves are absorbed by the liquid, and the degree of temperature rise is small. 5
is the case without cleaning liquid, the ultrasonic wave only heats the cleaning tank, the temperature of the cleaning tank increases sharply, and the vibrator eventually breaks down.

The present invention eliminates the above-mentioned conventional drawbacks and provides an ultrasonic cleaner that automatically stops the operation of the ultrasonic cleaner when there is no cleaning liquid and does not destroy the vibrator.

Examples of the present invention will be described below.

FIG. 5 shows an embodiment of the present invention.

T ₁ is an oscillation transformer, N ₁ is a primary winding, N ₂ and N ₃ are secondary windings, and the voltage generated in N ₁ is fed back to N ₂ and N ₃ to perform an oscillation operation. _N4 is a tertiary winding provided in addition to the oscillation winding, and a temperature switch SW is connected to the winding _N4 as a temperature controller. This temperature switch SW is normally in an open state, and when it operates abnormally and becomes over-temperature, it detects the temperature and shuts down. The oscillation circuit operates normally when the temperature switch SW is open. When the temperature switch SW is fired, the voltages generated at N ₁ , N ₂ , and N ₃ become zero, the oscillation operation stops, and no power is sent to the vibrator X. If this temperature switch is attached to a place where the temperature rises when there is no cleaning liquid and the temperature is detected, the operation will be stopped when there is no cleaning liquid, thereby preventing damage to the vibrator.

Figure 8 shows a diagram of this temperature switch SW installed in a cleaning tank. 4 is a temperature switch.

FIG. 6 shows a second embodiment. oscillation transformer
A thermal element (thermistor) R _th having a negative temperature coefficient is connected as a temperature controller to a separate winding N ₄ provided at T ₁ .

At this time, R _th detects a temperature rise when abnormal operation occurs, such as when there is no cleaning liquid, and the resistance value of R _th decreases, eventually stopping oscillation to protect the vibrator. When the heat sensitive element R _th is connected to N ₄ ,
FIG. 7 shows changes in the current i _x flowing through the vibrator X due to temperature rise. A is operating normally and the temperature is low. B
In this case, the temperature rises a little, and in C, the temperature rises further, and the resistance value of R _th becomes small and oscillation stops.

As can be seen from the above operation, when the heat-sensitive element R _th is used, the following effects are obtained in addition to preventing dry air.
If the time it takes to emit ultrasonic waves into the cleaning liquid is too long and the liquid temperature rises too much, this temperature is detected and the intensity of the ultrasonic waves is weakened, and when the liquid temperature drops, powerful ultrasonic waves are emitted again. It has the effect of keeping the liquid temperature constant.

FIG. 8 shows a diagram in which the heat-sensitive element 4 is attached to the cleaning tank 1. In Example 1, 4 was used as a temperature switch, but the same can be used as a heat-sensitive element.

As described above, in the ultrasonic cleaner of the present invention, the oscillation transformer is provided with another winding in addition to the oscillation winding, and this winding is equipped with a switch that switches on or off depending on the temperature rise. This system protects the oscillator by detecting the temperature rise when the oscillator becomes empty by connecting an element that reduces the oscillation temperature, and stops the oscillation operation.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram of a conventional ultrasonic cleaner, Figure 2
E ₁ and i _x are the voltage and current waveform diagrams in Figure 1, Figure 3 is a cross-sectional view of the same vibrator attached to a cleaning tank, Figure 4 is a temperature rise characteristic diagram of the cleaning tank, and Figure 5 is a circuit diagram of an ultrasonic cleaner according to an embodiment of the present invention, FIG. 6 is a circuit diagram of another embodiment, and FIGS. 7A, B,
C is a vibrator current waveform diagram of the circuit of FIG. 6, and FIG. 8 is a sectional view of the same temperature switch or heat-sensitive element attached to a cleaning tank. X...Ultrasonic vibrator, SW...Temperature switch,
R _th ...Thermal element, _T1 ...Oscillation transformer, _N1 ...
Primary winding of oscillation transformer T ₁ , N ₂ , N ₃ ... secondary winding of oscillation transformer T ₁ , N ₄ ... tertiary winding provided in oscillation transformer T ₁ .

Claims (1)

[Scope of Claims] 1. Consisting of a vibrator that generates ultrasonic waves, an oscillation circuit that flows a high-frequency current through the vibrator, and an oscillation transformer that feeds back the vibrator current and drives the oscillation circuit, the oscillation transformer includes: A separate winding is provided,
This ultrasonic cleaner has a temperature controller attached to the cleaning tank connected to this separate winding. 2. The ultrasonic cleaner according to claim 1, wherein the temperature controller is a temperature switch that operates based on temperature. 3. The ultrasonic cleaner according to claim 1, wherein the temperature controller is a heat-sensitive element having a negative temperature coefficient.