Single-end water level detecting device, electric kettle and control circuit

Abstract

The application relates to a single-end water level detection device, an electric kettle and a control circuit, which adopts a single-end electrode and a signal processing module, and the single-end electrode is arranged on the inner bottom and / or inner circumferential side of the kettle body of the electric kettle; the single-end electrode is electrically connected with the signal processing module arranged outside the kettle body through an electric connecting line; the signal processing module is electrically connected with the control unit of the electric kettle; the single-end electrode is used for generating a corresponding capacitance value according to the liquid capacity in the kettle body, and transmitting the capacitance value to the signal processing module through the electric connecting line; the signal processing module is used for generating a water level value corresponding to the liquid capacity according to the received capacitance value, and transmitting the water level value to the control unit, so that the control unit controls the electric kettle to perform corresponding water filling operation. Through the application, the water level can be accurately detected, water overflow during water filling of the electric kettle is avoided, the user's use feeling is improved, and the production cost is reduced.

Description

Technical Field

[0001] This application relates to the field of electric kettle technology, and in particular to a single-end water level detection device, an electric kettle, and a control circuit. Background Technology

[0002] Electric kettles and other small household appliances have become frequently used appliances in people's daily lives. Currently, there are various types of water level detection devices for electric kettles, such as float-type, pressure-type, and ultrasonic-type. However, current water level detection devices still have some drawbacks in bottom-filling applications. For example, float-type water level detection devices are easily interfered with by impurities, which affect the float's movement and cause significant deviations in the detected water volume, leading to malfunctions in the kettle's water filling control, resulting in insufficient water or overflow. Pressure-type water level detection devices require converting the water volume or level parameters into pressure parameters that can be sensed by a pressure sensor, necessitating the construction of a pressure sensing scenario and complex pressure sensor installation, which also increases the water level detection error and raises the production cost of the kettle. Existing ultrasonic water level detection devices are easily affected by environmental factors and are also costly.

[0003] Currently, no effective solution has been proposed for the problem that the water level detection device in the electric kettle has a large detection error, which easily causes the kettle to have too little water or overflow. Utility Model Content

[0004] In view of this, it is necessary to provide a single-ended water level detection device, an electric kettle, and a control circuit to at least solve the problems of large water level detection errors and easy occurrence of insufficient water or overflowing water in the electric kettle in the related technology.

[0005] In a first aspect, this application provides a technical solution as follows: a single-ended water level detection device for an electric kettle, comprising a single-ended electrode and a signal processing module. The single-ended electrode is installed on the inner bottom and / or inner circumference of the kettle body. The single-ended electrode is also electrically connected to the signal processing module located outside the kettle body via an electrical connection line. The signal processing module is also coupled and electrically connected to the control unit of the electric kettle. The single-ended electrode is used to generate a corresponding capacitance value based on the volume of liquid injected into the kettle body, and transmits the capacitance value to the signal processing module via the electrical connection line. The signal processing module is used to generate a water level value corresponding to the liquid volume based on the received capacitance value, and transmits the water level value to the control unit, so that the control unit controls the electric kettle to perform a corresponding water filling operation.

[0006] In one embodiment, the single-ended electrode includes a capacitive liquid level sensor.

[0007] In one embodiment, the single-ended electrode is further covered with an insulating protective layer for electrically isolating and protecting the single-ended electrode.

[0008] In one embodiment, the signal processing module includes an MC1081 digital capacitance sensor chip. One detection electrode port of the MC1081 digital capacitance sensor chip is electrically connected to the single-ended electrode and an ESD protection diode, respectively. The end of the ESD protection diode away from the one detection electrode port is grounded. The I²C interface of the MC1081 digital capacitance sensor chip is coupled and electrically connected to the control unit through an I²C serial communication bus. The MC1081 digital capacitance sensor chip is used to generate the corresponding water level value based on the capacitance value generated by the liquid level change in the vessel body sensed by the single-ended electrode.

[0009] Secondly, this application provides a technical solution as follows: a control circuit for an electric kettle, including the single-ended water level detection device described in the first aspect, and further including a power control module, a heating wire, an NTC temperature detection unit, and a water filling module. One end of the heating wire is electrically connected to the neutral wire of the mains power grid, and the other end is electrically connected to the output terminal of the power switch of the power control module. The input terminal of the power switch of the power control module is electrically connected to the live wire of the mains power grid. The controlled terminal of the power switch is coupled and electrically connected to the power adjustment control port of the control unit. The NTC temperature detection unit includes a temperature detection sensor disposed inside the kettle body. The temperature detection sensor is electrically connected to the temperature detection port of the control unit. The heating wire and the power switch form a series circuit with both ends respectively connected to the live wire and the neutral wire. The water module includes a water pump and a water pump drive circuit. The positive electrode of the water pump is electrically connected to a first power supply, the negative electrode of the water pump is electrically connected to the input terminal of the water pump drive circuit, the controlled terminal of the water pump drive circuit is electrically connected to the water supply control port of the control unit, and the output terminal of the water pump drive circuit is grounded. The control unit is used to control the water pump drive circuit to drive the water pump to perform water supply operation according to the generated water level value. The NTC temperature detection unit is used to detect the current water temperature of the liquid added to the kettle by the water supply module. The control unit is also used to control the switching of the power switch according to the current water temperature to control the on / off state of the series circuit, and to control the on / off state of the heating wire and the live wire through the series circuit, so as to control the heating wire to heat up and control the water temperature.

[0010] In one embodiment, the power control module further includes a power switch driving circuit, which includes an optocoupler-controlled silicon relay and a first switching transistor. The first switching transistor includes a first port, a second port, and a third port. The first port is electrically connected to a first resistor and a second resistor, respectively. The end of the first resistor opposite to the connection to the first port is electrically connected to the power regulation control port. The end of the second resistor opposite to the connection to the first port is electrically connected to the third port and grounded. The second port is electrically connected to the cathode of the light emitter of the optocoupler-controlled silicon relay. The anode of the light emitter of the optocoupler-controlled silicon relay is electrically connected to a second power supply via a third resistor in series. The first electrode of the light receiver of the optocoupler-controlled silicon relay is connected to the output terminal of the power switch via a first coupling resistor in series. The second electrode of the light receiver of the optocoupler-controlled silicon relay is connected to the controlled terminal of the power switch via a second coupling resistor in series.

[0011] The control unit is used to output the corresponding power control signal;

[0012] The first switching transistor is used to control the on / off state of the second port and the third port according to the level of the power control signal received at the first port;

[0013] The optocoupler-controlled silicon relay is used to generate a first control signal output along the second electrode of the photodetector of the optocoupler-controlled silicon relay when the second port is connected to the third port, and to generate a second control signal output along the first electrode of the photodetector of the optocoupler-controlled silicon relay when the second port is disconnected from the third port.

[0014] The power switch is configured to connect the input and output terminals of the power switch when the first control signal is received from the optocoupler controllable silicon relay, and to disconnect the input and output terminals of the power switch when the second control signal is received from the optocoupler controllable silicon relay.

[0015] The series circuit is used to control the connection or disconnection of the heating wire and the live wire according to the on / off state of the input and output terminals of the power switch, so that the heating wire can generate heat accordingly.

[0016] In one embodiment, the power control module further includes a zero-crossing detection circuit. The zero-crossing detection circuit includes a first sampling circuit and a first optocoupler. The first sampling circuit includes a first diode, a first voltage-dividing resistor, and a second voltage-dividing resistor connected in series. The anode of the first diode is electrically connected to the live wire. The connection point of the first and second voltage-dividing resistors is electrically connected to the anode of the emitter of the first optocoupler. The other end of the second voltage-dividing resistor, away from its connection to the first voltage-dividing resistor, is electrically connected to the neutral wire and the cathode of the emitter of the first optocoupler. The collector of the photodetector of the first optocoupler is electrically connected to a first power supply via a first pull-up resistor. The emitter of the photodetector of the first optocoupler is electrically connected to a first RC filter circuit and a third coupling resistor. The other end of the first RC filter circuit, away from its connection to the emitter of the photodetector of the first optocoupler, is grounded. The other end of the third coupling resistor, away from its connection to the emitter of the photodetector of the first optocoupler, is electrically connected to the zero-crossing detection port of the control unit.

[0017] The first sampling circuit is used to sample a DC detection signal that characterizes the voltage magnitude of the AC power in the mains grid;

[0018] The first optocoupler is used to convert the DC detection signal into a corresponding zero-crossing detection signal;

[0019] The control unit is configured to generate a corresponding zero-crossing control signal based on the magnitude of the zero-crossing detection signal, and control the switching of the power switch based on the corresponding zero-crossing control signal.

[0020] In one embodiment, the control circuit further includes a power supply module, the power supply module comprising:

[0021] The rectifier circuit includes a varistor, a filter capacitor, and a rectifier bridge. The varistor and the filter capacitor form a front-end filter unit. The input terminal of the front-end filter unit is connected to the mains power grid, and its output terminal is connected to the input terminal of the rectifier bridge. The output terminal of the rectifier bridge is connected to the primary winding of the inverter transformer. The rectifier circuit is used to rectify the AC power input from the mains power grid into DC voltage. The inverter transformer also includes a secondary winding and an auxiliary winding.

[0022] The main control circuit includes a switching power supply control chip. The power port of the switching power supply control chip is electrically connected to the output terminal of the rectifier circuit via a voltage divider circuit composed of multiple resistors connected in series. The power port is also electrically connected to the corresponding terminal of the auxiliary winding via a voltage regulator circuit composed of a second diode and a current-limiting resistor connected in series. The feedback port of the switching power supply control chip is also electrically connected to the corresponding terminal of the auxiliary winding via a positive feedback circuit composed of multiple sampling resistors connected in series. The power switch control port of the switching power supply control chip is electrically connected to the corresponding terminal of the primary winding. The secondary winding is electrically connected to the output terminal of the power module via an output rectifier circuit and a buck circuit connected in sequence. The output rectifier circuit includes parallel rectifier diodes and an RC snubber network. The buck circuit includes a DC-DC buck unit composed of a three-terminal Zener diode and surrounding capacitors and inductors.

[0023] The rectifier circuit is used to provide power for the switching power supply control chip to start.

[0024] The auxiliary winding is used to supply power to the switching power supply control chip after it is started.

[0025] The switching power supply control chip is used to obtain a status signal reflecting the DC voltage output by the rectifier circuit through the positive feedback circuit, so as to control the internal power switch to be turned on / off, and to make the inverter transformer convert the DC voltage rectified by the rectifier circuit into a high-frequency square wave pulse voltage and output it along the secondary winding.

[0026] The output rectifier circuit is used to rectify the high-frequency square wave pulse voltage into a second voltage corresponding to the second power supply.

[0027] The step-down circuit is used to step down the second voltage to the first voltage corresponding to the first power supply.

[0028] In one embodiment, the switching power supply control chip includes an OB2573TCPA power chip, and / or the three-terminal regulator includes a CJT1117B-5V three-terminal regulator.

[0029] Secondly, embodiments of this application also provide an electric kettle, including a control circuit for controlling the operation of the electric kettle, wherein the control circuit is the control circuit for the electric kettle described in the second aspect.

[0030] Compared with related technologies, this embodiment provides a single-ended water level detection device, an electric kettle, and a control circuit. It employs a single-ended electrode and a signal processing module. The single-ended electrode is installed on the inner bottom and / or inner circumference of the kettle body. The single-ended electrode is also electrically connected to the signal processing module located outside the kettle body via an electrical connection line. The signal processing module is also coupled and electrically connected to the control unit of the electric kettle. The single-ended electrode generates a corresponding capacitance value based on the volume of liquid injected into the kettle body and transmits this capacitance value to the signal processing module via the electrical connection line. The signal processing module generates a water level value corresponding to the liquid volume based on the received capacitance value and transmits this water level value to the control unit, enabling the control unit to control the electric kettle to perform the corresponding water filling operation. This solves the problems of large water level detection errors and easy overflow of electric kettles caused by water level detection devices in related technologies. It achieves accurate water level detection, avoids water overflow, improves user experience, and reduces production costs.

[0031] Details of one or more embodiments of this application are set forth in the following drawings and description to make other features, objects and advantages of this application more readily apparent. Attached Figure Description

[0032] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the present invention and, together with the description, serve to explain the principles of the present invention.

[0033] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 A structural block diagram of a single-end water level detection device provided in an embodiment of this application;

[0035] Figure 2 This is a topology diagram of the control unit according to an embodiment of this application;

[0036] Figure 3 This is a topology circuit diagram of the signal processing module in an embodiment of this application;

[0037] Figure 4 This is a structural block diagram of the control circuit of the electric kettle according to an embodiment of this application;

[0038] Figure 5 This is a topology diagram of the power control module according to an embodiment of this application;

[0039] Figure 6 This is a topological diagram of the water supply module according to an embodiment of this application;

[0040] Figure 7 This is a schematic diagram of the topology of the NTC temperature detection unit according to an embodiment of this application;

[0041] Figure 8 This is a topology diagram of the alarm module according to an embodiment of this application;

[0042] Figure 9 This is a topology circuit diagram of a power supply module according to a preferred embodiment of this application. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0044] The electric kettle and control circuit of this application will be described below with reference to the accompanying drawings in the embodiments of this application and through specific embodiments.

[0045] refer to Figures 1 to 3 The single-ended water level detection device provided in this application embodiment is used for an electric kettle. It includes a single-ended electrode 100 and a signal processing module 200. The single-ended electrode 100 is installed on the inner bottom and / or inner circumference of the kettle body. The single-ended electrode 100 is also electrically connected to the signal processing module 200 located outside the kettle body via an electrical connection line 300. The signal processing module 200 is also electrically coupled to the control unit 400 of the electric kettle (in this embodiment, this corresponds to a communication connection).

[0046] In this embodiment, the control unit 400 can be a single-chip microcomputer (MCU), a digital signal processor (DSP), or a programmable logic device (FPGA). In some optional embodiments, the control unit 100 preferably uses one of the following MCUs: BF7613BM28 microprocessor, R7F0C908B2 microprocessor, STC15F204 single-chip microcomputer, AT89S52 single-chip microcomputer, or EN8F677E microprocessor.

[0047] In this embodiment, the single-ended electrode 100 includes, but is not limited to, a capacitive liquid level sensor. In this embodiment, the single-ended electrode 100 is used to generate a corresponding capacitance value according to the liquid volume injected into the vessel, and transmit the capacitance value to the signal processing module 200 through the electrical connection line 300. In this embodiment, the single-ended electrode 100 is also covered with an insulating protective layer for electrically isolating and protecting the single-ended electrode 100, thereby preventing corrosion and short circuit of the single-ended electrode 100.

[0048] In this embodiment, the signal processing module 200 is used to generate a water level value corresponding to the liquid capacity based on the received capacitance value, and transmit the water level value to the control unit 400 so that the control unit 400 controls the electric kettle to perform the corresponding water filling operation.

[0049] In some of these alternative implementations, refer to Figure 3 The signal processing module 200 includes an MC1081 digital capacitance sensor chip IC2, and one detection electrode port of the MC1081 digital capacitance sensor chip IC2 (reference). Figure 3 Pin C5 of IC2 is electrically connected to single-ended electrode 100 and ESD protection diode DR1, respectively. The end of ESD protection diode DR1 furthest from the detection electrode port is grounded. The I²C interface of MC1081 digital capacitance sensor chip IC2 (see reference) Figure 3 The SDA and SCL pins of IC2 communicate via the I²C serial bus (see reference). Figure 2 and Figure 3 Network labels SDA and SCL are electrically coupled to control unit 400, wherein...

[0050] The MC1081 digital capacitive sensing chip IC2 is used to generate a corresponding water level value based on the capacitance value generated by the change in liquid level in the pot sensed by the single-ended electrode 100.

[0051] In this embodiment, the MC1081 digital capacitive sensing chip IC2, together with the surrounding resistors and capacitors and the single-ended electrode 100 (as an external capacitor Csensor), constitutes a capacitive sensor. When measuring the water level, different water volumes will generate different oscillation signals. After frequency division by the MC1081 digital capacitive sensing chip IC2, the signals are sent to the digital logic circuit to measure and digitize the oscillation signal frequency. The digital logic uses a reference frequency to measure the oscillation signal frequency. Using the reference capacitor inside the MC1081 digital capacitive sensing chip IC2, the capacitance corresponding to the oscillation signal frequency is calculated from the DATA value in the register through a calculation formula. The change in capacitance is obtained, and the control unit 400 determines the current water level in the kettle in real time based on the change in capacitance and a preset capacitance water level parameter table.

[0052] Understandably, the MC1081 digital capacitive sensing chip IC2 operates by connecting a single-ended electrode to measure the water level inside the kettle. In one optional embodiment, the MC1081 digital capacitive sensing chip IC2 is connected to multiple single-ended electrodes to measure the current water level inside the kettle and perform linear regression on the current water level to determine the real-time water level inside the kettle, thereby providing accuracy in detecting the water level inside the kettle and achieving precise control of water filling in the electric kettle.

[0053] It should be noted that the control unit 400 can control the electric kettle to fill, stop, and boil water based on the water level measured by the single-ended water level detection device. How the control unit 400 controls the operation of the electric kettle based on the water level does not constitute a limitation on the embodiments of this application, nor does the embodiments of this application limit it.

[0054] The aforementioned single-ended water level detection device, by setting a single-ended electrode 100 and a signal processing module 200, achieves accurate detection of the water level inside the electric kettle. This solves the problem of large water level detection errors and easy overflow of the electric kettle caused by water level detection devices in related technologies. It achieves accurate water level detection, avoids water overflow from the electric kettle, improves user experience, and reduces production costs.

[0055] refer to Figures 1 to 9 The control circuit for the electric kettle provided in this application embodiment includes the single-ended water level detection device in the above embodiment, and also includes a power control module 500, a heating wire 600, an NTC temperature detection unit 700, and a water filling module 800 electrically connected to the control unit 400. One end of the heating wire 600 is connected to the neutral wire N of the mains power grid (reference). Figure 5 The AC1 terminal is electrically connected to the power switch 51 of the power control module 500, and the other end is connected to the output terminal of the power switch 51 (see reference). Figure 5 The electrical connection between TR1 and T2 in the power control module 500 is the input terminal of the power switch 51 (see reference). Figure 5 TR1 (T1) is connected to the live wire L of the mains power grid, and the controlled terminal of power switch 51 (refer to...) Figure 5 TR1 (G) and the power regulation control port of control unit 400 (reference) Figure 2 The NTC temperature sensing unit 700 includes a temperature sensor (reference) located inside the kettle body, which is electrically coupled to pin 11 of IC1. Figure 7 CN5 connection terminal), temperature detection port of temperature detection sensor and control unit 400 (reference) Figure 2 The IC1's pin 1 is electrically connected, the heating wire 600 and the power switch 51 form a series circuit with their two ends electrically connected to the live wire L and the neutral wire N respectively, and the water filling module 800 includes a water pump 81 (see reference). Figure 6The CN11 connection terminal and the water pump drive circuit 82 are connected, and the positive electrode of the water pump 81 is connected to the first power supply (reference). Figure 6 The network label VCC12 (the first power supply is a 12V power supply) is electrically connected. The negative electrode of water pump 81 is electrically connected to the input terminal of water pump drive circuit 82. The controlled terminal of water pump drive circuit 82 is connected to the water supply control port of control unit 400 (see reference). Figure 2 The second pin of IC1 is electrically connected, and the output of the water pump drive circuit 82 is grounded.

[0056] The control unit 400 is used to control the water pump drive circuit 82 to drive the water pump 81 to perform the corresponding water filling operation according to the generated water level value.

[0057] In this embodiment, reference Figure 6 The water pump drive circuit 82 includes a switching transistor Q12. The switching transistor Q12 has an input terminal connected to the input terminal of the water pump drive circuit 82, a control terminal connected to the controlled terminal of the water pump drive circuit 82, and an output terminal connected to the output terminal of the water pump drive circuit 82. The control terminal of the switching transistor Q12 is connected to the water supply control port of the control unit 400 (reference) via a sixth coupling resistor R41 in series. Figure 2 The second pin of IC1 is electrically connected, and the control terminal of the switch Q12 is also electrically connected to an RC bypass circuit composed of capacitor C32 and resistor R45 for filtering. The output terminal of the switch Q12 is grounded. In this embodiment, the switch Q12 is used to control the on / off state of the input and output terminals of the switch Q12 according to the water supply control signal received by the control terminal of the switch Q12, so as to control the water pump 81 to perform the corresponding water pumping operation by enabling the connection and disconnection of the negative electrode of the water pump 81 to ground.

[0058] In this embodiment, when the single-ended water level detection device detects a low water level in the kettle, the main control chip IC1 corresponding to the control unit 400 outputs a high-level water supply control signal along its water supply control port, so that the switch Q12 connects its input and output terminals, thereby pulling the negative electrode of the water pump 81 to ground, energizing the water pump 81 and pumping water into the electric kettle; when the single-ended water level detection device detects that the water volume in the kettle has reached the set water volume, the main control chip IC1 corresponding to the control unit 400 outputs a low-level water supply control signal along its water supply control port, so that the switch Q12 is turned off and the water pump 81 stops pumping water.

[0059] The NTC temperature detection unit 700 is used to detect the current water temperature of the liquid added to the kettle by the water filling module 800.

[0060] In this embodiment, reference Figure 7The NTC temperature detection unit 700 uses an NTC thermistor to measure the water temperature inside the kettle, and provides the data basis for the control unit 400 to control the kettle to boil water by measuring the water temperature.

[0061] The control unit 400 is also used to control the switching of the power switch 51 according to the current water temperature to control the on / off state of the series circuit, and to control the on / off state of the heating wire 600 and the live wire through the series circuit, so as to control the heating wire 600 to heat up and control the water temperature.

[0062] In this embodiment, when the power switch 51 is open, the series circuit is broken, and the heating wire 600 is disconnected from the live wire L (corresponding to AC2). The heating wire 600 cannot form a power-conducting circuit and therefore cannot conduct electricity, meaning the heating wire 600 stops heating. When the power switch 51 is controlled to connect its input and output terminals, the electrode corresponding to the heating wire 600 is connected to the live wire L, thereby connecting the heating wire 600 with the live wire L and the neutral wire N, forming a power-conducting circuit, and the heating wire 600 is powered on and works.

[0063] In some embodiments, reference 4 and Figure 5 The power control module 500 also includes a power switch drive circuit 52, which includes an optocoupler thyristor relay UA and a first switching transistor Q1. The first switching transistor Q1 includes a first port, a second port, and a third port. The first port is electrically connected to a first resistor R114 and a second resistor R116, respectively. The end of the first resistor R114 that is away from the first port is connected to the power regulation control port (see reference). Figure 2 The first electrode of IC1 is electrically connected to pin 11. The end of the second resistor R116 opposite to the first port is electrically connected to the third port and grounded. The second port is electrically connected to the cathode of the light emitter of the optocoupler-controlled silicon relay UA. The anode of the light emitter of the optocoupler-controlled silicon relay UA is electrically connected to the second power supply (corresponding to a 5V power supply, denoted as +5V) through the third resistor R113 in series. The first electrode of the light receiver of the optocoupler-controlled silicon relay UA is connected in series with the first coupling resistor (composed of resistors R111 and R110 in series) and then connected to the power switch 51 (reference). Figure 5 The output terminal of TR in the reference ( Figure 5 In the middle TR1 (T2), the second electrode of the photodetector of the optocoupler controllable silicon relay UA is connected in series with the second coupling resistor R112 and the controlled terminal of the power switch 51 (reference). Figure 5 The G terminal of TR1 is electrically connected, where,

[0064] The control unit 400 is used to output the corresponding power control signal.

[0065] The first switching transistor Q1 is used to control the on / off state of the second and third ports according to the level of the power control signal received at the first port.

[0066] In this embodiment, when the power control signal received by the first port is at a preset high level, the second port and the third port are connected; when the power control signal received by the first port is at a preset low level, the second port and the third port are disconnected.

[0067] It should be noted that the first switching transistor Q1 in the embodiments of this application includes, but is not limited to, transistors, MOSFETs, and field-effect transistors. Furthermore, based on the disclosure of this application, those skilled in the art can readily conceive of modifying the first switching transistor disclosed in this application into a power switch drive circuit adapted to the specific selection of the switching transistor. Therefore, this application can be implemented regardless of whether the switching transistor is an NPN or PNP transistor, an N-channel or P-channel switching MOSFET, or an N-type or P-type field-effect transistor. This application is not limited in the embodiments of this application. In some optional embodiments, the first switching transistor is preferably a BC846B type transistor.

[0068] An optocoupler-controlled silicon relay UA is used to generate a first control signal output along the second electrode of the photodetector of the optocoupler-controlled silicon relay UA when the second port and the third port are connected, and to generate a second control signal output along the first electrode of the photodetector of the optocoupler-controlled silicon relay UA when the second port and the third port are disconnected.

[0069] In this embodiment, the optocoupler-controllable silicon relay UA includes one of the following: MOC3063 optocoupler, MOC3021 optocoupler, or IL420 optocoupler.

[0070] The power switch 51 is used to connect the input and output terminals of the power switch 51 when a first control signal is received from the optocoupler controllable silicon relay UA, and to disconnect the input and output terminals of the power switch when a second control signal is received from the optocoupler controllable silicon relay UA.

[0071] The series circuit is used to control the connection or disconnection of the heating wire 600 and the live wire L according to the on / off state of the input and output terminals of the power switch 51, so that the heating wire 600 can generate heat accordingly.

[0072] In this embodiment, when the input and output terminals of the power switch 51 are disconnected, the corresponding series circuit is open, and the heating wire 600 stops heating; when the input and output terminals of the power switch 51 are connected, the corresponding series circuit is connected, and the heating wire 600 is energized and heats up.

[0073] In some embodiments, reference Figure 2 , Figure 4 and Figure 5 The power control module 500 also includes a zero-crossing detection circuit 53, which includes a first sampling circuit and a second optocoupler UE. The first sampling circuit includes a first diode D4, a first voltage divider resistor (composed of resistors RX1 and RX2 connected in series), and a second voltage divider resistor RX3 connected in series. The anode of the first diode D4 is electrically connected to the live wire L. The connection point between the first voltage divider resistor and the second voltage divider resistor RX3 (corresponding to the connection point of RX2 and RX3, which is also the corresponding sampling point) is electrically connected to the anode of the emitter of the second optocoupler UE. The other end of the second voltage divider resistor RX3, away from the one electrically connected to the first voltage divider resistor, is electrically connected to the neutral wire N and the cathode of the emitter of the second optocoupler UE (see reference). Figure 5 In the network label AC1), the collector of the receiver of the second optocoupler UE is electrically connected to the second power supply (corresponding to +5V) through the first pull-up resistor R27. The emitter of the receiver of the second optocoupler UE is electrically connected to the second RC filter circuit (composed of resistor R28 and capacitor C12) and the fourth coupling resistor R130, respectively. The other end of the second RC filter circuit that is electrically connected to the emitter of the receiver of the second optocoupler UE is grounded. The other end of the fourth coupling resistor R130 that is electrically connected to the emitter of the receiver of the second optocoupler UE is connected to the zero-crossing detection port of the control unit 400 (reference). Figure 2 Pin 18 of IC1, and the corresponding connections and signal transmissions can be found in section 2. Figure 5 The network label ZERO) is electrically connected, where,

[0074] The first sampling circuit is used to sample the DC detection signal that represents the voltage magnitude of the AC power in the municipal power grid.

[0075] In this embodiment, the input terminal of the first sampling circuit is connected after the resistor R133 that couples the mains power grid to the control circuit of the electric kettle. The AC signal of the mains power grid is converted into a DC signal after passing through the first diode D4. Then, the signal is sampled by the voltage divider circuit composed of the first voltage divider resistor and the second voltage divider resistor RX3. Based on the sampled signal, the voltage of the AC power grid is determined. In this embodiment, the DC detection signal is a pulsating DC voltage.

[0076] The second optocoupler UE is used to convert the DC detection signal into the corresponding zero-crossing detection signal.

[0077] In this embodiment, the second optocoupler UE includes, but is not limited to, one of the following: PC817, EL817, TLP781. In this embodiment, EL817 is preferred. The use of linear optocouplers achieves strong and weak current isolation and improves circuit safety.

[0078] In this embodiment, when the level corresponding to the DC detection signal is 0V, the light emitter of the second optocoupler UE does not work, the second optocoupler UE is turned off, and the output terminal ZERO of the zero-crossing detection circuit outputs a low level. When the level corresponding to the DC detection signal is not 0, the light emitter of the second optocoupler UE works, the second optocoupler UE is turned on, and the output terminal ZERO of the zero-crossing detection circuit outputs a high level.

[0079] The control unit 400 is used to generate a corresponding zero-crossing control signal based on the magnitude of the zero-crossing detection signal, and control the switching of the power switch 51 based on the corresponding zero-crossing control signal.

[0080] In this embodiment, the second optocoupler UE is in the on state for most of the time during one cycle of the DC detection signal. The zero-crossing control signal is a very narrow rectangular pulse. After the 18th pin of the main control chip IC1 corresponding to the control unit 400 receives the rectangular pulse, it controls the power output according to the time when the rectangular pulse appears.

[0081] In some embodiments, reference Figure 2 , Figure 4 and Figure 5 The power control module 500 also includes a heating detection circuit 54, which comprises a second sampling circuit and a third optocoupler UG. The second sampling circuit includes a diode D8, a third voltage divider resistor (composed of resistors RX6 and RX7 connected in series), and a fourth voltage divider resistor RX8 connected in series. The anode of diode D8 is electrically connected to the output terminal of power switch 51. The connection point between the third and fourth voltage divider resistors RX8 (corresponding to the connection point of RX6 and RX7, which is also the corresponding sampling point) is electrically connected to the anode of the light emitter of the third optocoupler UG. The other end of the second voltage divider resistor RX3, away from the connection with the third voltage divider resistor, is electrically connected to the live wire L and the cathode of the light emitter of the third optocoupler UG, respectively (see reference). Figure 5 In the network label AC2), the collector of the photodetector of the third optocoupler UG is electrically connected to the second power supply (corresponding to +5V) through the third pull-up resistor R25. The emitter of the photodetector of the third optocoupler UG is electrically connected to the third RC filter circuit (composed of resistor R26 and capacitor C16) and the fifth coupling resistor R129, respectively. The other end of the third RC filter circuit, away from the photodetector of the third optocoupler UG, is grounded. The other end of the fifth coupling resistor R129, away from the photodetector of the third optocoupler UG, is connected to the heating detection port of the control unit 400 (reference). Figure 2 Pin 12 of IC1, and the corresponding connections and signal transmission can be found in [reference needed]. Figure 2 and Figure 5 The network label HT-Check1) is electrically connected.

[0082] The second sampling circuit is used to sample the DC detection signal that characterizes the magnitude of the AC voltage at the output terminal of the power switch 51.

[0083] In this embodiment, the input terminal of the second sampling circuit is connected to the output terminal of the power switch 51. The AC signal at the output terminal of the power switch 51 is converted into a DC signal after passing through diode D8. Then, the signal is sampled by a voltage divider circuit composed of a third voltage divider resistor and a fourth voltage divider resistor RX8. Based on the sampled signal, the voltage magnitude at the output terminal of the power switch 51 is determined.

[0084] The third optocoupler UG is used to convert the DC detection signal into the corresponding heating detection signal.

[0085] In this embodiment, the third optocoupler UG includes, but is not limited to, one of the following: PC817, EL817, TLP781. In this embodiment, EL817 is preferred. The use of linear optocouplers achieves strong and weak current isolation and improves circuit safety.

[0086] In this embodiment, when the level corresponding to the DC detection signal is 0V, the light emitter of the third optocoupler UG does not work, the third optocoupler UG is cut off, and the output terminal of the heating detection circuit outputs a low level. When the level corresponding to the DC detection signal is not 0, the light emitter of the third optocoupler UG works, the third optocoupler UG is turned on, and the output terminal of the heating detection circuit outputs a high level.

[0087] The control unit 400 is used to generate a corresponding heating control signal based on the level of the heating detection signal, and to control the switching of the power switch 51 based on the corresponding heating control signal to perform heating control work.

[0088] In some embodiments, reference Figure 8 The control circuit in this embodiment further includes an alarm circuit, which includes a buzzer SP1 and a buzzer driver circuit. The buzzer driver circuit includes a switching transistor Q14, which has a fourth port, a fifth port, and a sixth port. The fourth port is connected to the alarm control port of the control unit 400 (see reference) through a fifth coupling resistor R38 in series. Figure 2 The fourth port is electrically connected to the fifth port via an RC bypass circuit consisting of capacitor C34 and resistor R39. The fifth port is also connected to ground. The sixth port is electrically connected to the first terminal of buzzer SP1 and resistor R37. The other end of resistor R37, away from the sixth port, is electrically connected to the second terminal of buzzer SP1 and resistor R36. The other end of resistor R36, away from resistor R37, is connected to the second power supply (corresponding to +5V power supply).

[0089] In this embodiment, the control unit 400 judges the corresponding working status of the electric kettle during the working process according to the corresponding module connected to it, such as: whether the water temperature has reached the boiling point, whether the water temperature has reached the water temperature threshold of the set mode, whether there is water in the electric kettle, abnormal water boiling, abnormal water pumping, etc. When it is judged that an abnormality has occurred or the normal working state has been exceeded, the alarm module is controlled to sound an alarm.

[0090] In this embodiment, when an alarm is required, the control unit 400 outputs a high level along its alarm control port. After receiving the high level, the fourth port of the switching transistor Q14 controls its fifth and sixth ports to connect, thereby pulling the fifth port down to ground. The buzzer SP1 is then powered on and puts the alarm into operation.

[0091] It should be noted that the switching transistor Q14 in the embodiments of this application includes, but is not limited to, transistors, MOSFETs, and field-effect transistors. Furthermore, based on the disclosure of this application, those skilled in the art can easily conceive of modifying the switching transistor Q14 disclosed in this application to an alarm circuit adapted to the specific selection of the switching transistor Q14. Therefore, this application can be implemented regardless of whether the switching transistor is an NPN or PNP transistor, an N-channel or P-channel switching MOSFET, or an N-type or P-type field-effect transistor, and is not limited in the embodiments of this application.

[0092] Figure 9 This is a topology circuit diagram of the power supply module according to a preferred embodiment of this application. To supply power to the signal processing module 200, control unit 400, power control module 500, NTC temperature detection unit 700, water filling module 800, and alarm module, a first power supply (outputting a +12V first voltage) and a second power supply (outputting a +5V second voltage) are formed. (Refer to...) Figure 9 The control circuit in this embodiment further includes a power supply module 900, which includes:

[0093] The rectifier circuit includes a varistor VR1, a filter capacitor X1, and a rectifier bridge B1. The varistor VR1 and the filter capacitor X1 form a front-end filter unit. The input terminal of the front-end filter unit is connected to the mains power grid (live wire L and neutral wire N), and its output terminal is connected to the input terminal of the rectifier bridge B1. The output terminal of the rectifier bridge B1 is connected to the primary winding of the inverter transformer TF1. The rectifier circuit is used to rectify the AC power input from the mains power grid into DC voltage. The inverter transformer TF1 also includes a secondary winding and an auxiliary winding.

[0094] The main control circuit includes a switching power supply control chip U3. The power supply port VDD of the switching power supply control chip U3 is electrically connected to the output of the rectifier circuit via a voltage divider circuit composed of multiple resistors (R5, R6) connected in series. The power supply port VDD is also electrically connected to the corresponding terminal of the auxiliary winding via a voltage regulator circuit composed of a second diode D3 connected in series and a current-limiting resistor R9. The feedback port FB of the switching power supply control chip U3 is also electrically connected to the corresponding terminal of the auxiliary winding via a positive feedback circuit composed of multiple sampling resistors (R10, R11) connected in series. The power switch control port of the switching power supply control chip U3 (see reference)... Figure 9 Pins 5-8 of U3 are electrically connected to the corresponding terminals of the primary winding. The secondary winding is electrically connected to the output terminal of the power module 900 through an output rectifier circuit and a step-down circuit connected in sequence. The output rectifier circuit includes a parallel rectifier diode D1 and an RC snubber network (composed of R14 and C4). The step-down circuit includes a DC step-down unit composed of a three-terminal Zener diode U8 and surrounding capacitors and inductors.

[0095] In this embodiment, the switching power supply control chip U3 includes, but is not limited to, the OB2573TCPA power chip, and the three-terminal voltage regulator U8 includes, but is not limited to, the CJT1117B-5V three-terminal voltage regulator chip.

[0096] In this embodiment, the rectifier circuit is used to provide power for the switching power supply control chip U3 to start; the auxiliary winding is used to supply power to the switching power supply control chip U3 after it starts.

[0097] In this embodiment, the switching power supply control chip U3 is used to obtain the status signal reflecting the DC voltage output of the rectifier circuit through the positive feedback circuit, so as to control the internal power switch to turn on / off, so that the inverter transformer TF1 converts the DC voltage rectified by the rectifier circuit into a high-frequency square wave pulse voltage and outputs it along the secondary winding.

[0098] In this embodiment, the output rectifier circuit is used to rectify the high-frequency square wave pulse voltage into a first voltage (+12V) corresponding to the first power supply; the step-down circuit is used to step down the first voltage into a second voltage (+5V) corresponding to the second power supply.

[0099] This application also provides an electric kettle, including a control circuit for controlling the operation of the electric kettle, which is the control circuit of the electric kettle in the above embodiment.

[0100] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive elements that are not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0101] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A single-ended water level detection device for an electric kettle, characterized in that, The device includes a single-ended electrode and a signal processing module. The single-ended electrode is installed on the inner bottom and / or inner circumference of the kettle body. The single-ended electrode is also electrically connected to the signal processing module located outside the kettle body via an electrical connection wire. The signal processing module is also coupled and electrically connected to the control unit of the kettle. The single-ended electrode is used to generate a corresponding capacitance value based on the volume of liquid injected into the pot, and to transmit the capacitance value to the signal processing module through the electrical connection line. The signal processing module is used to generate a water level value corresponding to the liquid capacity based on the received capacitance value, and transmit the water level value to the control unit so that the control unit controls the electric kettle to perform the corresponding water filling operation.

2. The single-end water level detection device according to claim 1, characterized in that, The single-ended electrode includes a capacitive liquid level sensor.

3. The single-end water level detection device according to claim 2, characterized in that, The single-ended electrode is also covered with an insulating protective layer for electrical isolation and protection of the single-ended electrode.

4. The single-end water level detection device according to claim 2, characterized in that, The signal processing module includes an MC1081 digital capacitance sensor chip. One detection electrode port of the MC1081 digital capacitance sensor chip is electrically connected to the single-ended electrode and the ESD protection diode. The end of the ESD protection diode away from the detection electrode port is grounded. The I²C interface of the MC1081 digital capacitance sensor chip is coupled and electrically connected to the control unit through an I²C serial communication bus. The MC1081 digital capacitance sensor chip is used to generate the corresponding water level value based on the capacitance value generated by the liquid level change in the vessel body sensed by the single-ended electrode.

5. A control circuit for an electric kettle, characterized in that, The device includes the single-ended water level detection device according to any one of claims 1 to 4, further comprising a power control module, a heating wire, an NTC temperature detection unit, and a water filling module. One end of the heating wire is electrically connected to the neutral wire of the mains power grid, and the other end is electrically connected to the output terminal of the power switch of the power control module. The input terminal of the power switch of the power control module is electrically connected to the live wire of the mains power grid, and the controlled terminal of the power switch is coupled and electrically connected to the power adjustment control port of the control unit. The NTC temperature detection unit includes a temperature detection sensor disposed inside the kettle body, and the temperature detection sensor is electrically connected to the temperature detection port of the control unit. The heating wire and the power switch form a series circuit with their two ends respectively electrically connected to the live wire and the neutral wire. The water filling module includes a water pump and a water pump drive circuit. The positive electrode of the water pump is electrically connected to a first power supply, and the negative electrode of the water pump is electrically connected to the input terminal of the water pump drive circuit. The controlled terminal of the water pump drive circuit is electrically connected to the water supply control port of the control unit, and the output terminal of the water pump drive circuit is grounded. The control unit is used to control the water pump drive circuit to drive the water pump to perform water filling operation according to the generated water level value. The NTC temperature detection unit is used to detect the current water temperature of the liquid added to the kettle by the water filling module; The control unit is also used to control the switching of the power switch according to the current water temperature, so as to control the on / off state of the series circuit, and to control the on / off state of the heating wire and the live wire through the series circuit, so as to control the heating wire to heat up and control the water temperature accordingly.

6. The control circuit according to claim 5, characterized in that, The power control module further includes a power switch drive circuit, which comprises an optocoupler-controlled silicon relay and a first switching transistor. The first switching transistor includes a first port, a second port, and a third port. The first port is electrically connected to a first resistor and a second resistor, respectively. The end of the first resistor opposite to the first port is electrically connected to the power adjustment control port. The end of the second resistor opposite to the first port is electrically connected to the third port and grounded. The second port is electrically connected to the cathode of the light emitter of the optocoupler-controlled silicon relay. The anode of the light emitter of the optocoupler-controlled silicon relay is electrically connected to a second power supply via a third resistor in series. The first electrode of the light receiver of the optocoupler-controlled silicon relay is connected to the output terminal of the power switch via a first coupling resistor in series. The second electrode of the light receiver of the optocoupler-controlled silicon relay is connected to the controlled terminal of the power switch via a second coupling resistor in series. The control unit is used to output the corresponding power control signal; The first switching transistor is used to control the on / off state of the second port and the third port according to the level of the power control signal received at the first port; The optocoupler-controlled silicon relay is used to generate a first control signal output along the second electrode of the photodetector of the optocoupler-controlled silicon relay when the second port is connected to the third port, and to generate a second control signal output along the first electrode of the photodetector of the optocoupler-controlled silicon relay when the second port is disconnected from the third port. The power switch is configured to connect the input and output terminals of the power switch when the first control signal is received from the optocoupler controllable silicon relay, and to disconnect the input and output terminals of the power switch when the second control signal is received from the optocoupler controllable silicon relay. The series circuit is used to control the connection or disconnection of the heating wire and the live wire according to the on / off state of the input and output terminals of the power switch, so that the heating wire can generate heat accordingly.

7. The control circuit according to claim 6, characterized in that, The power control module further includes a zero-crossing detection circuit, which comprises a first sampling circuit and a first optocoupler. The first sampling circuit includes a first diode, a first voltage-dividing resistor, and a second voltage-dividing resistor connected in series. The anode of the first diode is electrically connected to the live wire. The connection point of the first and second voltage-dividing resistors is electrically connected to the anode of the emitter of the first optocoupler. The other end of the second voltage-dividing resistor, away from its connection to the first voltage-dividing resistor, is electrically connected to the neutral wire and the cathode of the emitter of the first optocoupler. The collector of the photodetector of the first optocoupler is electrically connected to a first power supply through a first pull-up resistor. The emitter of the photodetector of the first optocoupler is electrically connected to a first RC filter circuit and a third coupling resistor. The other end of the first RC filter circuit, away from its connection to the emitter of the photodetector of the first optocoupler, is grounded. The other end of the third coupling resistor, away from its connection to the emitter of the photodetector of the first optocoupler, is electrically connected to the zero-crossing detection port of the control unit. The first sampling circuit is used to sample a DC detection signal that characterizes the voltage magnitude of the AC power in the mains grid; The first optocoupler is used to convert the DC detection signal into a corresponding zero-crossing detection signal; The control unit is configured to generate a corresponding zero-crossing control signal based on the magnitude of the zero-crossing detection signal, and control the switching of the power switch based on the corresponding zero-crossing control signal.

8. The control circuit according to claim 5, characterized in that, The control circuit further includes a power supply module, which comprises: The rectifier circuit includes a varistor, a filter capacitor, and a rectifier bridge. The varistor and the filter capacitor form a front-end filter unit. The input terminal of the front-end filter unit is connected to the mains power grid, and its output terminal is connected to the input terminal of the rectifier bridge. The output terminal of the rectifier bridge is connected to the primary winding of the inverter transformer. The rectifier circuit is used to rectify the AC power input from the mains power grid into DC voltage. The inverter transformer also includes a secondary winding and an auxiliary winding. The main control circuit includes a switching power supply control chip. The power port of the switching power supply control chip is electrically connected to the output terminal of the rectifier circuit via a voltage divider circuit composed of multiple resistors connected in series. The power port is also electrically connected to the corresponding terminal of the auxiliary winding via a voltage regulator circuit composed of a second diode and a current-limiting resistor connected in series. The feedback port of the switching power supply control chip is also electrically connected to the corresponding terminal of the auxiliary winding via a positive feedback circuit composed of multiple sampling resistors connected in series. The power switch control port of the switching power supply control chip is electrically connected to the corresponding terminal of the primary winding. The secondary winding is electrically connected to the output terminal of the power module via an output rectifier circuit and a buck circuit connected in sequence. The output rectifier circuit includes parallel rectifier diodes and an RC snubber network. The buck circuit includes a DC-DC buck unit composed of a three-terminal Zener diode and surrounding capacitors and inductors. The rectifier circuit is used to provide power for the switching power supply control chip to start. The auxiliary winding is used to supply power to the switching power supply control chip after it is started. The switching power supply control chip is used to obtain a status signal reflecting the DC voltage output by the rectifier circuit through the positive feedback circuit, so as to control the internal power switch to be turned on / off, and to make the inverter transformer convert the DC voltage rectified by the rectifier circuit into a high-frequency square wave pulse voltage and output it along the secondary winding. The output rectifier circuit is used to rectify the high-frequency square wave pulse voltage into a second voltage corresponding to the second power supply. The step-down circuit is used to step down the second voltage to the first voltage corresponding to the first power supply.

9. The control circuit for the electric kettle according to claim 8, characterized in that, The switching power supply control chip includes an OB2573TCPA power chip, and / or the three-terminal voltage regulator includes a CJT1117B-5V three-terminal voltage regulator.

10. An electric kettle, characterized in that, The device includes a control circuit for controlling the operation of an electric kettle, the control circuit comprising the control circuit for an electric kettle as described in any one of claims 5 to 9.

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