Dry burning prevention protection circuit of ultrasonic cleaning machine

Abstract

The utility model discloses an ultrasonic cleaner dry burning prevention protection circuit, which comprises a single chip microcomputer U1, a boost drive circuit, a water level detection circuit and a power supply circuit, the power supply circuit is used for outputting 5V direct current voltage and 12V direct current voltage, the 12V direct current voltage is loaded at the input end of the boost drive circuit, and the water level detection circuit is used for detecting the water level of the water level detection circuit. The single-chip microcomputer U1 is used for loading a PWM driving signal to a control end of the boost driving circuit, two output ends of the boost driving circuit are connected to a load interface of an ultrasonic water tank steel basin, the boost driving circuit is used for boosting and converting 12V direct-current voltage into alternating-current power supply voltage according to the PWM driving signal, and the water level detection circuit comprises a mutual inductor L1 and an operational amplifier U3. The two input ends of the mutual inductor L1 are connected to a load interface of an ultrasonic water tank steel basin, the two output ends of the mutual inductor L1 are connected to the in-phase end and the anti-phase end of the operational amplifier U3 respectively, and the output end of the operational amplifier U3 is connected to the single-chip microcomputer U1. The ultrasonic cleaning machine can be prevented from working in a water-free state, the service life is prolonged, and the safety is improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to ultrasonic cleaning machine especially relates to an ultrasonic cleaning machine dry -burning protection circuit. BACKGROUND

[0002] Ultrasonic cleaning machine radiates ultrasonic wave to the water in the cleaning basin during work, and can remove dirt on the surface of the article based on high frequency vibration and cavitation effect, with the increase of cleaning time, especially when the equipment works for a long time, the water in the steel basin of the sink may become high temperature state, the water in the steel basin of the sink may become water shortage, no water and other states due to evaporation, the power of the whole machine increases, which causes the circuit board to catch fire and other problems, and there is a safety hazard. SUMMARY

[0003] The utility model solves the technical problem in prior art, provides a dry -burning protection circuit that can prevent ultrasonic cleaning machine from working in waterless state, can improve the service life and safety of ultrasonic cleaning machine.

[0004] To solve the above technical problems, the utility model adopts the following technical scheme.

[0005] A kind of ultrasonic cleaning machine dry -burning protection circuit, it includes single-chip microcomputer U1, boost drive circuit, water level detection circuit and power supply circuit, the power supply circuit is used to output 5V direct current voltage and 12V direct current voltage, the 12V direct current voltage is loaded on the input end of the boost drive circuit, the single-chip microcomputer U1 is used to load PWM drive signal to the control end of the boost drive circuit, the two output ends of the boost drive circuit are connected to the load interface of ultrasonic sink steel basin, the boost drive circuit is used to convert the 12V direct current voltage into alternating current supply voltage according to the PWM drive signal, the water level detection circuit includes mutual inductor L1 and operational amplifier U3, the two input ends of the mutual inductor L1 are connected to the load interface of ultrasonic sink steel basin, the two output ends of the mutual inductor L1 are connected to the noninverting input and inverting input of the operational amplifier U3 respectively, and the output end of the operational amplifier U3 is connected to the single-chip microcomputer U1.

[0006] Preferably, the water level detection circuit includes resistance R47 and resistance R42, and the resistance R47 and the resistance R42 are connected in series to one input end of the mutual inductor L1.

[0007] Preferably, the water level detection circuit includes resistance R43, resistance R39 and resistance R46, the resistance R39 and the resistance R46 are connected in series to the two output ends of the mutual inductor L1 respectively, and the resistance R43 is connected between the two output ends of the mutual inductor L1.

[0008] Preferably, the water level detection circuit comprises a resistor R38 connected between the inverting terminal and the output terminal of the operational amplifier U3.

[0009] Preferably, the boost driving circuit comprises a transformer T1, a MOS tube Q4, a MOS tube Q8, a first PWM driving branch and a second PWM driving branch, the input terminals of the first PWM driving branch and the second PWM driving branch are connected to the single-chip microcomputer U1, the single-chip microcomputer U1 loads a PWMA signal to the first PWM driving branch and loads a PWMB signal to the second PWM driving branch, the output terminal of the first PWM driving branch is connected to the gate of the MOS tube Q8, the source of the MOS tube Q8 is grounded, the drain of the MOS tube Q8 is connected to the first terminal of the primary winding of the transformer T1, the output terminal of the second PWM driving branch is connected to the gate of the MOS tube Q4, the source of the MOS tube Q4 is grounded, the drain of the MOS tube Q4 is connected to the second terminal of the primary winding of the transformer T1, the middle tap of the primary winding of the transformer T1 is connected to a 12V DC voltage terminal, and the secondary winding of the transformer T1 is used to output the AC power supply voltage.

[0010] Preferably, a resistor R4, a resistor R9, a resistor R5 and a resistor R26 are included, the resistor R4 is connected in series between the gate of the MOS tube Q4 and the output terminal of the second PWM driving branch, the resistor R9 is connected between the gate and the source of the MOS tube Q4, the resistor R5 is connected in series between the gate of the MOS tube Q8 and the output terminal of the first PWM driving branch, and the resistor R26 is connected between the gate and the source of the MOS tube Q8.

[0011] Preferably, a whole machine power detection circuit is included, the whole machine power detection circuit comprises an operational amplifier U4, the source of the MOS tube Q4 is grounded through a resistor R28, the source voltage of the MOS tube Q4 is transmitted to the non-inverting terminal of the operational amplifier U4, the inverting terminal of the operational amplifier U4 is grounded through a resistor R53 and a resistor R48 connected in parallel with each other, and the output terminal of the operational amplifier U4 is connected to the single-chip microcomputer U1.

[0012] Preferably, the whole machine power detection circuit comprises a resistor R40 and a resistor R51, the resistor R40 and the resistor R51 are connected in parallel with each other and then connected in series between the source of the MOS tube Q4 and the non-inverting terminal of the operational amplifier U4.

[0013] The utility model discloses an ultrasonic cleaning machine dry -burning protection circuit prevents dry -burning protection circuit, including power supply circuit, water level detection circuit, power detection circuit, PA6 / AD0 pin receives water level detection signal and through PWM signal control Q1-Q11 element realizes step -up conversion through the singlechip U1, and the water level detection circuit is through the mutual -inductor L1 and the operational amplifier U3 will alternating voltage attenuate and convert into analog voltage, and then through AD converts into digital signal, when detecting that water level is lower than the preset value, the singlechip U2 controls the step -up drive circuit and stops working, and sends out the alarm signal through the buzzer BZ1, thereby realizes the dry -burning protection, compared with prior art, the utility model not only can prevent ultrasonic cleaning machine in the water state work, can also improve ultrasonic cleaning machine service life and security. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 It is the singlechip and peripheral circuit schematic diagram;

[0015] Figure 2 It is the step -up drive circuit schematic diagram;

[0016] Figure 3 It is the load interface schematic diagram of ultrasonic water tank steel basin;

[0017] Figure 4 It is the water level detection circuit and whole machine power detection circuit schematic diagram;

[0018] Figure 5 It is the dry -burning protection circuit composition block diagram. DETAILED DESCRIPTION

[0019] The utility model will be described in more detail in connection with the drawings and examples.

[0020] The utility model discloses an ultrasonic cleaning machine dry -burning protection circuit, combines Figures 1 to 5As shown, it includes single-chip microcomputer U1, boost drive circuit, water level detection circuit and power supply circuit, the power supply circuit is used for outputting 5V DC voltage and 12V DC voltage, the 12V DC voltage is loaded on the input end of the boost drive circuit, the single-chip microcomputer U1 is used for loading PWM drive signal to the control end of the boost drive circuit, two output ends of the boost drive circuit are connected to the load interface of the ultrasonic water tank steel basin, the boost drive circuit is used for converting the 12V DC voltage into AC power supply voltage according to the PWM drive signal, the water level detection circuit includes mutual inductor L1 and operational amplifier U3, two input ends of the mutual inductor L1 are connected to the load interface of the ultrasonic water tank steel basin, two output ends of the mutual inductor L1 are connected to the noninverting input terminal and the inverting input terminal of the operational amplifier U3 respectively, and the output end of the operational amplifier U3 is connected to the single-chip microcomputer U1. Further, the alarm circuit is connected to the single-chip microcomputer U1, and includes a sound alarm.

[0021] In the above circuit, the power supply circuit can output 5V DC voltage and 12V DC voltage, the 5V DC voltage is used for supplying power for the single-chip microcomputer U1 and other circuits, and the 12V DC voltage is used for providing basic voltage for the boost drive circuit. In the water level collection process, the single-chip microcomputer U1 receives the water level detection signal through the PA6 / AD0 pin, and controls Q1-Q11 elements to realize boost conversion through the PWM signal. In the water level detection circuit, the alternating voltage is attenuated and converted into analog voltage through the mutual inductor L1 and the operational amplifier U3, and then converted into digital signal through AD. When detecting that the water level is lower than the preset value, the single-chip microcomputer U2 controls the boost drive circuit to stop working, and sends out an alarm signal through the buzzer BZ1, so as to realize dry burning protection. Compared with the prior art, the ultrasonic cleaning machine can not only work in the waterless state, but also can improve the service life and safety of the ultrasonic cleaning machine.

[0022] In the specific detection process of the embodiment, Figure 3 and Figure 4 As shown, the water tank steel basin load voltage L, N represents that when there is no load, the voltage value is AC 93V, when there is a load water tank steel basin with water, the voltage value is AC 104V, and when there is a load water tank steel basin without water, the voltage value is AC 83V. After the above three different voltage values, the R42\R47 resistor is attenuated, and then a weak voltage is coupled out through the L1 mutual inductor or transformer isolation, and the R43 resistor stabilizes and balances the voltage, and then the digital voltage is obtained through the U3 differential operational amplifier or other operational amplifier mode. The voltage value is 0.2V without basin, 1V without water, and 1.4V or above with water, which is sent to the single-chip microcomputer for identification and judgment processing.

[0023] For the specific circuit structure of the water level detection circuit, please refer to Figure 4The water level detection circuit comprises a resistor R47 and a resistor R42, the resistor R47 and the resistor R42 are connected in series to one input end of the mutual inductor L1.

[0024] As to the load interface seat, the interface UL1 is a load interface of the sink steel basin, and is used for connecting the voltage of the sink steel basin load, which is about AC 115V (L, N). The resistor R42 and the resistor R47 are attenuation resistors. The mutual inductor L1 is a coupling transformer or a mutual inductor. The resistor R43 is a voltage stabilizing resistor.

[0025] Further, the water level detection circuit comprises a resistor R43, a resistor R39 and a resistor R46. The resistor R39 and the resistor R46 are connected in series to two output ends of the mutual inductor L1 respectively. The resistor R43 is connected between the two output ends of the mutual inductor L1.

[0026] As a preferred mode, the water level detection circuit comprises a resistor R38, which is connected between the inverting terminal and the output terminal of the operational amplifier U3.

[0027] In the above circuit, the water level detection circuit attenuates and converts the AC 200V voltage into an analog voltage through the mutual inductor L1 and the operational amplifier U3, and then converts the analog voltage into a digital signal through AD conversion. Specifically, after the water level detection circuit is added with the AC 200V voltage, the AC voltage is attenuated into an analog voltage through the mutual inductor, the analog voltage is converted into a digital voltage through the operational amplifier, and then the digital voltage is transmitted to the AD port of the single-chip microcomputer to identify the voltage level. Based on the above detection process, when the cleaning basin is waterless, the digital voltage is 1V, and when the cleaning basin has water, the digital voltage is 2V.

[0028] In actual application, with the change of the voltage of the load of the sink steel basin with water and without water, the resistance lossless attenuation, the isolation coupling conversion of the mutual inductor, and the stable weak voltage of the operational amplifier, the digital voltage after the amplification of the operational amplifier is transmitted to the single-chip microcomputer to identify that the voltage is 0.2V when there is no load, the voltage is 1V when there is a load without water, and the voltage is 1.4V or above when there is a load with water.

[0029] As to the peripheral circuit of the operational amplifier, the resistor R39 and the resistor R46 are differential input resistors of the operational amplifier U3. The resistor R38 is the amplification multiple of the operational amplifier U3. The resistor R37 is a current limiting resistor. The capacitor C15 and the capacitor C19 are filter capacitors, which are used for detecting the water amount voltage of the sink steel basin and transmitting the voltage to the single-chip microcomputer for identification.

[0030] As to the peripheral circuit of the single-chip microcomputer U1, the resistor R1 is a power supply resistor of the single-chip microcomputer U1. The capacitor C4 and the capacitor C5 are filter capacitors of the single-chip microcomputer U1. The single-chip microcomputer U1 is a control chip of the driving board circuit.

[0031] The circuit principle of the voltage boosting driving circuit is shown in Figure 2 The voltage boosting driving circuit comprises a transformer T1, a MOS tube Q4, a MOS tube Q8, a first PWM driving branch and a second PWM driving branch. The input end of the first PWM driving branch and the input end of the second PWM driving branch are respectively connected to the single-chip microcomputer U1. The single-chip microcomputer U1 loads a PWMA signal to the first PWM driving branch and loads a PWMB signal to the second PWM driving branch. The output end of the first PWM driving branch is connected to the gate of the MOS tube Q8. The source of the MOS tube Q8 is grounded. The drain of the MOS tube Q8 is connected to the first input end of the transformer T1. The output end of the second PWM driving branch is connected to the gate of the MOS tube Q4. The source of the MOS tube Q4 is grounded. The drain of the MOS tube Q4 is connected to the second input end of the transformer T1. The two output ends of the transformer T1 are used to output the alternating current power supply voltage.

[0032] In the above circuit, the first PWM driving branch is composed of an NPN tube Q9, an NPN tube Q10, an NPN tube Q7, a PNP tube Q11 and a plurality of auxiliary resistors and capacitors. The second PWM driving branch is composed of an NPN tube Q2, an NPN tube Q3, an NPN tube Q1, a PNP tube Q5 and a plurality of auxiliary resistors and capacitors. Based on the two driving signals PWMA and PWMB output by the single-chip microcomputer U1, the single-chip microcomputer U1 converts the direct current 12 volts into alternating current 200 volts by the PWM driving mode, so as to supply the cleaning basin.

[0033] The auxiliary circuit of the voltage boosting driving circuit comprises a resistor R4, a resistor R9, a resistor R5 and a resistor R26. The resistor R4 is connected in series between the gate of the MOS tube Q4 and the output end of the second PWM driving branch. The resistor R9 is connected between the gate and the source of the MOS tube Q4. The resistor R5 is connected in series between the gate of the MOS tube Q8 and the output end of the first PWM driving branch. The resistor R26 is connected between the gate and the source of the MOS tube Q8.

[0034] The embodiment provides a PWM (pulse width modulation) driving circuit, which is mainly used for controlling two H-bridge circuits to drive a load. The following is the working mode of the circuit:

[0035] The PWM signal input: PWMB and PWMA are PWM control signal input ends, which are used for controlling the conduction and turn-off of MOSFET switches in the H-bridge;

[0036] About H bridge circuit: there are two H bridge circuits in the circuit, one is composed of NPN tube Q1, NPN tube Q2, NPN tube Q3 and PNP tube Q5, and the other is composed of NPN tube Q7, NPN tube Q9, NPN tube Q10 and PNP tube Q11. The H bridge circuit realizes the voltage polarity reversal of the output end by alternating on and off of MOSFET; the outputs of the two H bridge circuits are connected to LA end and LB end respectively;

[0037] About PWM control: when PWMB signal is high, NPN tube Q2 and NPN tube Q3 are turned on, NPN tube Q1 and PNP tube Q5 are turned off, so that positive voltage is generated at LA end; when PWMB signal is low, NPN tube Q1 and PNP tube Q5 are turned on, NPN tube Q2 and NPN tube Q3 are turned off, so that negative voltage is generated at LA end; similarly, PWMA signal controls the conduction and turn-off of NPN tube Q9 and NPN tube Q10, so as to control the voltage polarity of LB end;

[0038] Protection circuit: the circuit contains some protection elements, such as resistance R7, resistance R4, resistance R5, etc., which are used for current limiting and protection of MOSFET; capacitors C14, C12 and C17 are used for filtering to reduce the influence of power supply noise on the circuit;

[0039] About load driving: LA and LB ends can be connected to step-up transformer, and through PWM signal control H bridge circuit, the adjustment of DC to AC parameters can be realized.

[0040] As a preferred mode, please see Figure 4 , the embodiment includes a whole machine power detection circuit, specifically, the whole machine power detection circuit includes an operational amplifier U4, the source of the MOS tube Q4 is connected to ground through the resistance R28, the source voltage of the MOS tube Q4 is transmitted to the non-inverting terminal of the operational amplifier U4, the inverting terminal of the operational amplifier U4 is connected to ground through the resistance R53 and the resistance R48 which are connected in parallel with each other, and the output terminal of the operational amplifier U4 is connected to the single-chip microcomputer U1.

[0041] Further, the whole machine power detection circuit includes the resistance R40 and the resistance R51, which are connected in parallel with each other and then connected in series between the source of the MOS tube Q4 and the non-inverting terminal of the operational amplifier U4.

[0042] In the above circuit, node B is the resistance sampling voltage of MOS S pole, which is used to collect the power of the steel basin load, R40 and R51 are the input setting resistances of U4 operational amplifier, R39 and R46 are the differential input resistances of U3 operational amplifier, R38 is the amplification multiple of U3, R37 is the current limiting resistance, C15 and C19 are filter capacitors, and the water amount voltage of the steel basin is detected and sent to the single-chip microcomputer for identification; with the voltage change of the steel basin load with water and without water, resistance attenuation, isolation coupling conversion of the transformer, and stable weak voltage, the amplified digital voltage after operational amplification is sent to the single-chip microcomputer for identification, and the voltage is 0.2V when there is no load, 1V when there is load without water, and 1.4V or above when there is load with water.

[0043] The ultrasonic cleaning machine dry-burning protection circuit disclosed by the utility model, in practical application, input external direct current 12-volt voltage and provide stable power supply, for power supply part, 12-volt power supply supplies power to step-up transformer, and 12-volt is converted to 5-volt power supply to single-chip microcomputer through LDO; for single-chip microcomputer control part, single-chip microcomputer is converted into alternating current 200-volt from direct current 12-volt through PWM drive mode and step-up transformer, and supplies cleaning basin; for water level detection circuit, alternating current 200-volt voltage connected is converted into analog voltage through transformer mode, analog voltage is converted into digital voltage through operational amplification, and then digital voltage is sent to AD port of single-chip microcomputer and identified voltage height, when cleaning basin is without water, digital voltage is 1V, and when cleaning basin has water, digital voltage is 2-volt; for dry-burning protection circuit, when detecting that water level is lower than preset value (digital voltage is 1V), single-chip microcomputer control circuit stops working, and equipment damage is prevented.

[0044] Compared with the prior art, the utility model discloses through real -time monitoring liquid level or working medium state, prevent equipment from starting ultrasonic transducer when being without liquid or liquid deficiency, when equipment idling operation, the utility model discloses through intelligent control circuit and cut off power, avoid the problems such as transducer aging, circuit board burning caused by idling.This in addition, the transducer (vibrator) of ultrasonic cleaning machine relies on liquid medium transmission energy, and when liquid deficiency, will produce invalid vibration, leading to the unbalance of vibrator load.Dry-burning function can quickly identify abnormal working condition, reduce the risk of vibrator failure or resonance frequency deviation due to cavitation, so as to maintain the stability of high-frequency circuit and the output efficiency of transducer.

[0045] The above is only the preferred embodiment of the utility model, and is not used for limiting the utility model, and the modification, equivalent replacement or improvement, etc. made within the technical range of the utility model should be included in the range protected by the utility model.

Claims

1. A dry-burn protection circuit for an ultrasonic cleaner, characterized in that, The application relates to an ultrasonic water tank steel basin power supply device, which comprises a single-chip microcomputer U1, a voltage boosting driving circuit, a water level detection circuit and a power supply circuit, wherein the power supply circuit is used for outputting 5V direct current voltage and 12V direct current voltage, the 12V direct current voltage is loaded on the input end of the voltage boosting driving circuit, the single-chip microcomputer U1 is used for loading a PWM driving signal on the control end of the voltage boosting driving circuit, two output ends of the voltage boosting driving circuit are connected to the load interface of the ultrasonic water tank steel basin, the voltage boosting driving circuit is used for boosting and converting the 12V direct current voltage into alternating current power supply voltage according to the PWM driving signal, the water level detection circuit comprises a mutual inductor L1 and an operational amplifier U3, two input ends of the mutual inductor L1 are connected to the load interface of the ultrasonic water tank steel basin, two output ends of the mutual inductor L1 are respectively connected to the non-inverting input end and the inverting input end of the operational amplifier U3, and the output end of the operational amplifier U3 is connected to the single-chip microcomputer U1.

2. The anti-burnout protection circuit for an ultrasonic cleaning machine as claimed in claim 1, wherein The water level detection circuit comprises a resistor R47 and a resistor R42, and the resistor R47 and the resistor R42 are connected in series at one input end of the mutual inductor L1.

3. The anti-burnout protection circuit for an ultrasonic cleaning machine as claimed in claim 1, wherein The water level detection circuit comprises a resistor R43, a resistor R39 and a resistor R46, the resistor R39 and the resistor R46 are respectively connected in series at two output ends of the mutual inductor L1, and the resistor R43 is connected between the two output ends of the mutual inductor L1.

4. The dry fire protection circuit for an ultrasonic cleaning machine as defined in claim 1, wherein, The water level detection circuit comprises a resistor R38, and the resistor R38 is connected between the inverting input end and the output end of the operational amplifier U3.

5. The dry fire protection circuit for an ultrasonic cleaning machine as defined in claim 1, wherein, The voltage boosting driving circuit comprises a transformer T1, a MOS tube Q4, a MOS tube Q8, a first PWM driving branch and a second PWM driving branch, the input end of the first PWM driving branch and the input end of the second PWM driving branch are respectively connected to the single-chip microcomputer U1, the first PWM driving branch is loaded with a PWMA signal and the second PWM driving branch is loaded with a PWMB signal by the single-chip microcomputer U1, the output end of the first PWM driving branch is connected to the gate of the MOS tube Q8, the source of the MOS tube Q8 is grounded, the drain of the MOS tube Q8 is connected to the first end of the primary winding of the transformer T1, the output end of the second PWM driving branch is connected to the gate of the MOS tube Q4, the source of the MOS tube Q4 is grounded, the drain of the MOS tube Q4 is connected to the second end of the primary winding of the transformer T1, the middle tap of the primary winding of the transformer T1 is connected to the 12V direct current voltage end, and the secondary winding of the transformer T1 is used for outputting the alternating current power supply voltage.

6. The anti-burnout protection circuit for an ultrasonic cleaning machine as claimed in claim 5, wherein The voltage boosting driving circuit comprises a resistor R4, a resistor R9, a resistor R5 and a resistor R26, the resistor R4 is connected in series between the gate of the MOS tube Q4 and the output end of the second PWM driving branch, the resistor R9 is connected between the gate and the source of the MOS tube Q4, the resistor R5 is connected in series between the gate of the MOS tube Q8 and the output end of the first PWM driving branch, and the resistor R26 is connected between the gate and the source of the MOS tube Q8.

7. The dry fire protection circuit for an ultrasonic cleaning machine as defined in claim 6, wherein, Including the whole machine power detection circuit, the whole machine power detection circuit includes operational amplifier U4, the source of MOS tube Q4 is grounded through resistance R28, the source voltage of MOS tube Q4 is transmitted to the noninverting terminal of operational amplifier U4, the inverting terminal of operational amplifier U4 is grounded through resistance R53 and resistance R48 in parallel with each other, the output terminal of operational amplifier U4 is connected to the single-chip microcomputer U1.

8. The dry fire protection circuit for an ultrasonic cleaning machine as defined in claim 7, wherein, The whole machine power detection circuit includes resistance R40 and resistance R51, the resistance R40 and the resistance R51 are connected in series between the source of MOS tube Q4 and the noninverting terminal of operational amplifier U4 after being connected in parallel with each other.

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