Water heater protection circuit and water heater

Abstract

The utility model relates to a water heater protection circuit and a water heater. The water heater protection circuit comprises a power supply module; the relay is used for controlling on-off of the heating tube; a first end of a control coil of the relay is connected with the power module; the anti-dry-burning circuit is used for detecting the water level of the inner container; the anti-dry-burning circuit comprises a control module, a first switch tube, a first detection end, a second switch tube and a second detection end, the input end of the first switch tube is connected with the power supply module, and the output end of the first switch tube is connected with the first detection end; the input end of the second switch tube is connected with the second detection end, and the output end of the second switch tube is connected with the control module; the control module is also connected with the second end of the control coil; the electric leakage detection circuit is used for detecting electric leakage current of the inner container; the output end of the electric leakage detection circuit is connected with the control end of the first switching tube and the control end of the second switching tube. Leakage protection and dry burning prevention are completed by sharing one relay, and the circuit is simplified while the cost is reduced.

Description

Technical Field

[0001] The present application relates to the technical field of water heater safety protection, and in particular to a water heater protection circuit and a water heater. Background Art

[0002] Electric water heaters are widely used due to their convenience. Safety issues are extremely important in the use of electric water heaters. However, the applicant found that in the traditional technology, the leakage protection circuit and the dry-burning protection circuit work separately, and multiple relays are required for control, which is costly. Utility Model Content

[0003] The technical problem solved by the present application is to provide a water heater protection circuit and a water heater, which can effectively reduce the cost of the anti-leakage and anti-dry-burning protection circuits.

[0004] The above technical problems are solved by the following technical solutions:

[0005] In a first aspect, a water heater protection circuit is provided, which is applied to a water heater, wherein the water heater comprises an inner tank and a heating tube arranged in the inner tank, and the water heater protection circuit comprises:

[0006] Power module;

[0007] Relay, used to control the on and off of the heating tube;

[0008] The anti-dry-burning circuit is used to detect the water level of the inner pot; the anti-dry-burning circuit includes a control module, a first switch tube, a first detection end, a second switch tube and a second detection end, the input end of the first switch tube is connected to the power module, and the output end of the first switch tube is connected to the first detection end; the input end of the second switch tube is connected to the second detection end, and the output end of the second switch tube is connected to the control module; the control module controls the connection relay;

[0009] The leakage detection circuit is used to detect the leakage current of the inner tank; the output end of the leakage detection circuit is connected to the control end of the first switch tube and the control end of the second switch tube respectively.

[0010] The water heater protection circuit described in this application has the following beneficial effects compared with the background technology:

[0011] The first switch tube and the second switch tube in the anti-dry-burning circuit are used to combine the leakage detection circuit and the anti-dry-burning control. When the water heater leaks or the water level in the inner tank is insufficient, based on the first switch tube and the second switch tube, the relay can be triggered to disconnect the power supply path from the power module to the heating tube. By sharing a relay, the cost is reduced and the circuit is simplified while achieving anti-dry-burning protection and leakage protection. At the same time, by setting the first switch tube and the second switch tube, it can effectively prevent leakage current from entering the anti-dry-burning circuit and burning the components in the anti-dry-burning circuit.

[0012] In one embodiment, the control module includes:

[0013] A third switch tube, the output end of the third switch tube is connected to the relay, the control end of the third switch tube is connected to the output end of the second switch tube, and the input end of the third switch tube is grounded.

[0014] Using the third switch tube to control the relay is beneficial to product integration and reducing product size.

[0015] In one embodiment, the control circuit further comprises:

[0016] Diode, the diode is connected in parallel with the relay.

[0017] By providing a diode, a sudden increase in voltage applied to the relay when the third switch tube is turned on can be prevented, thereby preventing the device from burning out and increasing the service life of the control circuit.

[0018] In one embodiment, the first switch tube is a PNP transistor, and / or the second switch tube is a PNP transistor.

[0019] In one embodiment, the third switch tube is an NPN transistor.

[0020] In one embodiment, the leakage detection circuit includes:

[0021] The first capacitor is connected in series between the leakage detection point of the inner tank and the neutral line;

[0022] A bidirectional optocoupler, wherein the input light emitting diode of the bidirectional optocoupler is connected in series with the first capacitor, the collector of the output transistor of the bidirectional optocoupler is connected to the power module, and the emitter of the output transistor of the bidirectional optocoupler is connected to the control end of the first switch tube and the control end of the second switch tube.

[0023] When the leakage detection point is energized, the electrical signal output by the power module flows through the bidirectional optocoupler based on the AC-passing and DC-isolating function of the first capacitor. The bidirectional optocoupler conducts in both directions and outputs voltage to the control end of the first switch tube and the control end of the second switch tube, so that the first switch tube and the second switch tube are both turned off. At this time, the control coil of the relay is not energized, and the relay disconnects the path for the power module to supply power to the heating tube, thereby achieving leakage protection.

[0024] In one embodiment, the leakage detection circuit further includes:

[0025] At least one first current limiting module, the first current limiting module is connected in series with the first capacitor.

[0026] By configuring the first current limiting module, it is possible to prevent the device from burning out due to excessive output current of the power module, thereby increasing the service life of the water heater.

[0027] In one embodiment, the leakage detection circuit includes:

[0028] The second capacitor is connected in series between the leakage detection point of the inner tank and the neutral line;

[0029] an AC transformer, used for sensing a leakage current passing through the second capacitor;

[0030] A rectifier and filter circuit, wherein the input end of the rectifier and filter circuit is connected to the output end of the AC transformer; the output end of the rectifier and filter circuit is connected to the control end of the first switch tube and the control end of the second switch tube;

[0031] The clamping circuit is connected to the output end of the rectifier and filter circuit.

[0032] The AC power output by the power supply module is transmitted to the primary side of the AC transformer through the second capacitor. When the leakage detection point of the water heater is energized, the primary side path of the AC transformer is turned on. At this time, the secondary side of the AC transformer outputs an AC power to the rectifier and filter circuit. After the rectifier and filter circuit, the DC signal is output to the clamping circuit. After being clamped by the clamping circuit, a stable voltage is output to the control end of the first switch tube and the control end of the second switch tube, so that the first switch tube and the second switch tube are both turned off. At this time, the control coil of the relay is not energized, and the relay disconnects the path for the power supply module to the heating tube to achieve leakage protection.

[0033] In one embodiment, the water heater protection circuit further includes:

[0034] An alarm module, wherein an input end of the alarm module is connected to an output end of the leakage detection circuit.

[0035] When the water heater leaks electricity, the output end of the leakage detection circuit outputs a voltage to the alarm module, and the alarm module is powered on to work to remind the user that the water heater has leakage electricity.

[0036] In a second aspect, a water heater is provided, comprising the above-mentioned water heater protection circuit.

[0037] The water heater is equipped with the water heater protection circuit, and the anti-dry-burning circuit and the leakage detection circuit share a relay to complete leakage protection and anti-dry-burning, thereby reducing the cost and simplifying the circuit. At the same time, by providing the first switch tube and the second switch tube, it can effectively prevent the leakage current from entering the anti-dry-burning circuit and burning the components in the anti-dry-burning circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the conventional technology, the drawings required for use in the embodiments or the conventional technology descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0039] FIG1 is a schematic diagram of a water heater protection circuit according to an embodiment of the present invention;

[0040] Figure 2 This is a second structural schematic diagram of a water heater protection circuit according to an embodiment.

[0041] Description of reference numerals:

[0042] 10. Power supply module; 20. Relay; 30. Anti-dry burning circuit; 31. Control module; 311. First filter circuit; LJ. Wiring terminal; A. First detection end; B. Second detection end; 40. Leakage detection circuit; 41. First capacitor; 42. Bidirectional optocoupler; 43. First current limiting module; 44. Second current limiting module; 45. Second capacitor; 46. Rectification and filtering circuit; 461. Conversion circuit; 462. Half-wave rectification circuit; 463. Voltage divider circuit; 464. Second filter circuit; 47. Clamping circuit; 50. Alarm module. DETAILED DESCRIPTION

[0043] In order to facilitate understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. Embodiments of the present application are provided in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0044] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0045] It is understood that the terms "first", "second", etc. used in this application can be used to describe various elements in this article, but these elements are not limited by these terms. These terms are only used to distinguish a first element from another element. For example, without departing from the scope of this application, a first capacitor can be referred to as a second capacitor, and similarly, a second capacitor can be referred to as a first capacitor. Both the first capacitor and the second capacitor are capacitors, but they are not the same capacitor.

[0046] It can be understood that the “connection” in the following embodiments should be understood as “electrical connection”, “communication connection”, etc. if the connected circuits, modules, units, etc. have electrical signals or data transmission between each other.

[0047] It will be understood that “at least one” means one or more, and “plurality” means two or more.

[0048] When used herein, the singular forms "a", "an", and "said / the" may also include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "include / comprise" or "have" and the like specify the presence of stated features, wholes, steps, operations, components, parts, or combinations thereof, but do not exclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof. At the same time, the term "and / or" used in this specification includes any and all combinations of the relevant listed items.

[0049] In a first aspect, a water heater protection circuit is provided, which is applied to a water heater. The water heater includes an inner tank and a heating tube arranged in the inner tank. The water heater protection circuit includes: a power module 10; a relay 20, an anti-dry-burning circuit 30, and a leakage detection circuit 40.

[0050] The power module 10 is used to provide the working voltage required by each module connected thereto. The power module 10 can be connected to an external power source and receive an AC signal from the external power source, for example, the AC power loaded between the live wire ACL and the neutral wire ACN in the figure.

[0051] The relay 20 is used to control the power on and off of the heating tube; the first end of the control coil of the relay 20 is connected to the power module 10. The anti-dry-burning circuit 30 is used to detect the water level of the inner pot, and the anti-dry-burning circuit 30 includes a control module 31, a first switch tube Q1, a first detection terminal A, a second switch tube Q2 and a second detection terminal B. The first detection terminal A and the second detection terminal B are arranged at intervals. When there is water between the two detection terminals, they are connected based on the conductivity of the water, and are disconnected when there is no water. The input end of the first switch tube Q1 is connected to the power module 10, the output end of the first switch tube Q1 is connected to the first detection terminal A, the input end of the second switch tube Q2 is connected to the second detection terminal B, the output end of the second switch tube Q2 is connected to the control module 31, and the control module 31 is also connected to the second end of the control coil. Therefore, when the water level in the inner tank is lower than the minimum limit water level (a safe water level to prevent dry burning), there is no water between the first detection terminal A and the second detection terminal B, and the power supply path from the power module 10 to the control module 31 through the first switch tube Q1 and the second switch tube Q2 is disconnected. The control module 31 cannot drive the relay 20 to close. At this time, the heating tube stops heating, and anti-dry burning protection is achieved.

[0052] The leakage detection circuit 40 is used to detect the leakage current of the inner tank. The output end of the leakage detection circuit 40 is connected to the control end of the first switch tube Q1 and the control end of the second switch tube Q2 respectively. When the water heater leaks, the leakage detection circuit 40 outputs an electrical signal to the first switch tube Q1 and the second switch tube Q2, triggering the first switch tube Q1 and the second switch tube Q2 to shut down. At this time, the power supply path between the power module 10 and the control module 31 through the first switch tube Q1 and the second switch tube Q2 is disconnected, and the control module 31 cannot drive the relay 20 to close. At this time, the heating tube stops heating, and leakage protection is realized, that is, anti-dry burning protection and leakage protection are realized by sharing a relay 20, which reduces the cost.

[0053] In addition, the water heater protection circuit provided in the embodiment of the present application can effectively prevent leakage current from entering the anti-dry-burning circuit and burning the components in the anti-dry-burning circuit (weak current side) by setting a first switch tube and a second switch tube.

[0054] In one embodiment, the control module 31 includes: a third switch tube Q3.

[0055] The output end of the third switch tube Q3 is connected to the second end of the control coil of the relay 20 , the control end of the third switch tube Q3 is connected to the output end of the second switch tube Q2 , and the input end of the third switch tube Q3 is grounded.

[0056] When the inner tank is short of water, there is no water between the first detection terminal A and the second detection terminal B, and no voltage is loaded to the control end of the third switch tube Q3. The third switch tube Q3 is in the off state, and no output voltage is transmitted to the control coil of the relay 20. The relay 20 loses power and disconnects, and the heating tube loses power and does not work, thereby realizing anti-dry burning protection.

[0057] Using a switch tube to control the control coil of the relay 20 is beneficial to product integration and reducing product size.

[0058] In one embodiment, the third switch tube Q3 is an NPN transistor. The base of the NPN transistor serves as the control terminal of the third switch tube Q3, the emitter of the NPN transistor serves as the input terminal of the third switch tube Q3, the emitter of the NPN transistor can be grounded, and the collector of the NPN transistor serves as the output terminal of the third switch tube Q3. The base of the NPN transistor is turned on when a high level is connected, and is turned off when a low level is connected.

[0059] When the inner tank is short of water, there is no water between the first detection terminal A and the second detection terminal B, the base of the NPN transistor is at a low level, the NPN transistor is turned off, and the control coil of the relay 20 is not energized. At this time, the relay 20 is disconnected, the heating tube is powered off and stops working, realizing anti-dry burning protection.

[0060] When the water heater leaks, the leakage detection circuit 40 outputs an electrical signal to the first switch tube Q1 and the second switch tube Q2. The first switch tube Q1 and the second switch tube Q2 are in the off state. At this time, the base of the NPN transistor is at a low level, the NPN transistor is turned off, the control coil of the relay 20 is not energized, the relay 20 is disconnected, the heating tube is powered off and stops working, thereby achieving leakage protection.

[0061] In one embodiment, the connection between the input end of the first switch tube Q1 and the power module 10 , and between the output end of the second switch tube Q2 and the control module 31 , can be achieved through the connection terminal LJ.

[0062] In one embodiment, depending on the selection, some peripheral devices may be provided for the third switch tube Q3. For example, a bias resistor R1 may be connected across the input end and the control end of the third switch tube Q3, and a bias resistor R2 may be connected in series between the output end of the third switch tube Q3 and the second end of the control coil of the relay 20.

[0063] In one embodiment, the control module 31 may further include:

[0064] The first filter circuit 311 has an input end connected to the output end of the second switch tube Q2 , and an output end of the first filter circuit 311 connected to the control end of the third switch tube Q3 .

[0065] The first filtering circuit 311 may include:

[0066] The resistor R3 is connected in series between the output end of the second switch tube Q2 and the control end of the third switch tube Q3.

[0067] Capacitor C1, a first end of the capacitor C1 is respectively connected to the output end of the second switch tube Q2 and the control end of the third switch tube Q3, and a second end of the capacitor C1 is grounded.

[0068] In one embodiment, the water heater protection circuit further includes:

[0069] The current limiting resistor R4 has an input end connected to the output end of the leakage detection circuit 40 , and an output end of the current limiting resistor R4 is respectively connected to the control end of the first switch tube Q1 and the control end of the second switch tube Q2 .

[0070] In one embodiment, the control circuit further comprises:

[0071] The diode D1 has an anode connected to the second end of the control coil and a cathode connected to the first end of the control coil, that is, the diode D1 is forwardly connected between the second end of the control coil of the relay 20 and the first end of the control coil of the relay 20 .

[0072] By connecting a diode D1 across both ends of the control coil, it is possible to prevent the voltage loaded on the control coil from being too large when the third switch tube Q3 is turned on, and to clamp the voltage loaded on both ends of the control coil to near the working voltage of the relay 20 disconnection control, thereby preventing the device from burning out and increasing the service life of the control module 31. For example, in one embodiment, the diode D1 can clamp the voltage loaded on both ends of the control coil to near 5V.

[0073] In one embodiment, the first switch tube Q1 is a PNP transistor, and / or the second switch tube Q2 is a PNP transistor.

[0074] The input end of the first switch tube Q1 is the collector of the corresponding PNP transistor, the output end of the first switch tube Q1 is the emitter of the corresponding PNP transistor, and the control end of the first switch tube Q1 is the base of the corresponding PNP transistor.

[0075] The input end of the second switch tube Q2 is the collector of the corresponding PNP transistor, the output end of the second switch tube Q2 is the emitter of the corresponding PNP transistor, and the control end of the second switch tube Q2 is the base of the corresponding PNP transistor. The base of the PNP is disconnected when connected to a high level, and is turned on when connected to a low level. When the water heater leaks, the leakage detection circuit 40 outputs a high level to the first switch tube Q1 and the second switch tube Q2, the first switch tube Q1 and the second switch tube Q2 are turned off, and the power supply path from the power module 10 to the control module 31 through the first switch tube Q1 and the second switch tube Q2 is disconnected, the control coil of the relay 20 loses power, the relay 20 is disconnected, the heating tube is powered off and stops working, and leakage protection is achieved.

[0076] In one embodiment, the leakage detection circuit 40 includes a first capacitor 41 and a bidirectional optocoupler 42 .

[0077] The first capacitor 41 is connected in series between the leakage detection point of the inner tank and the neutral line ACN. The input light emitting diode of the bidirectional optocoupler 42 is connected in series with the first capacitor 41, the collector of the output transistor of the bidirectional optocoupler 42 is connected to the power module 10, and the emitter of the output transistor of the bidirectional optocoupler 42 is connected to the control end of the first switch tube Q1 and the control end of the second switch tube Q2.

[0078] When the water heater leaks electricity, the leakage detection point LD is energized, and the electrical signal output by the power module 10 flows through the bidirectional optocoupler 42 based on the AC-isolating function of the first capacitor 41, and the bidirectional optocoupler 42 conducts in both directions. The input light-emitting diode of the bidirectional optocoupler 42 emits light, triggering the output transistor of the bidirectional optocoupler 42 to turn on, and transmitting the voltage input by the power module 10 to the control end of the first switch tube Q1 and the control end of the second switch tube Q2, driving the first switch tube Q1 and the second switch tube Q2 to turn off, the control coil of the relay 20 loses power, the relay 20 is disconnected, and the heating tube loses power and does not work, thereby achieving leakage protection.

[0079] The voltage magnitude connected to the collector of the output transistor of the bidirectional optocoupler 42 from the power module 10 should be adapted to the magnitude requirement of the voltage connected to the control end of the first switch tube Q1 and the second switch tube Q2, so as to normally drive the first switch tube Q1 and the second switch tube Q2 on and off, and avoid burning the first switch tube Q1 and the second switch tube Q2. For example, the collector of the output transistor of the bidirectional optocoupler 42 can be connected to a 5V voltage from the power module 10.

[0080] In one embodiment, the first capacitor 41 can be a high-voltage ceramic capacitor.

[0081] In one embodiment, the leakage detection circuit 40 further includes: at least one first current limiting module 43. The first current limiting module 43 is connected in series with the first capacitor 41. For example, the first current limiting module 43 may include two, one of which is connected in series between the power module 10 and the input light emitting diode of the bidirectional optocoupler 42, and the other is connected in series between the output end of the first capacitor 41 and the leakage detection point LD.

[0082] By configuring the first current limiting module 43, when leakage occurs, the current flowing through the bidirectional optocoupler 42 can be within the tolerance range of the bidirectional optocoupler 42, thereby preventing the device from burning out due to excessive output current of the power module 10 and improving the life and reliability of the water heater protection circuit.

[0083] Optionally, each first current limiting module 43 may include a current limiting resistor.

[0084] In one embodiment, a second current limiting module 44 may be connected in series between the collector of the output transistor of the bidirectional optocoupler 42 and the power module 10. The second current limiting module 44 may include a current limiting resistor.

[0085] In one embodiment, the output transistor emitter of the bidirectional optocoupler 42 is also grounded through a capacitor C2 to filter and store energy for the electrical signal output by the output transistor emitter of the bidirectional optocoupler 42. The voltage output by the output transistor emitter of the bidirectional optocoupler 42 can be smoothly transmitted to the control end of the first switch tube Q1 and the control end of the second switch tube Q2.

[0086] In one embodiment, the leakage detection circuit 40 includes: a second capacitor 45 , an AC transformer TA, a rectifier and filter circuit 46 , and a clamping circuit 47 .

[0087] The second capacitor 45 is connected in series between the leakage detection point LD of the inner tank and the neutral line ACN. The AC transformer TA is used to sense the leakage current passing through the second capacitor 45. The input end of the rectifier and filter circuit 46 is connected to the output end of the AC transformer TA, and the output end of the rectifier and filter circuit 46 is connected to the control end of the first switch tube Q1 and the control end of the second switch tube Q2; the clamp circuit 47 is connected to the output end of the rectifier and filter circuit 46.

[0088] The AC power output by the power module 10 is transmitted to the primary side of the AC transformer TA through the second capacitor 45, and when the leakage detection point LD of the water heater is energized, the primary side path of the AC transformer TA is turned on. At this time, the secondary side of the AC transformer TA outputs an AC power to the rectifier filter circuit 46. After the rectifier filter circuit 46, a DC signal is output to the control end of the first switch tube Q1 and the control end of the second switch tube Q2. The clamp circuit 47 makes the DC signal output stably. The DC signal drives the first switch tube Q1 and the second switch tube Q2 to turn off. At this time, the control coil of the relay 20 is not energized, and the relay 20 disconnects the path for the power module 10 to supply power to the heating tube, realizing leakage protection.

[0089] In one embodiment, the second capacitor 45 may be a high voltage ceramic capacitor.

[0090] In one embodiment, the rectifying and filtering circuit 46 may include:

[0091] The conversion circuit 461 has an input end connected to the output end of the secondary side of the AC transformer TA, and is used to convert the current signal into a voltage signal;

[0092] A half-wave rectifier circuit, wherein the input end of the half-wave rectifier circuit is connected to the output end of the conversion circuit 461;

[0093] A voltage divider circuit 463, wherein an input end of the voltage divider circuit 463 is connected to an output end of the half-wave rectifier circuit;

[0094] The second filter circuit 464 has an input end connected to the output end of the voltage divider circuit 463 , and an output end of the second filter circuit 464 connected to the input end of the clamp circuit 47 .

[0095] Specifically, when the water heater leaks, the secondary side of the AC transformer TA outputs an induced current, which is output as a voltage signal through the conversion circuit 461, transmitted backward, rectified by the half-wave rectifier circuit, and output as a DC voltage signal. The DC voltage signal is divided by the voltage divider circuit 463 to output a voltage signal that matches the working voltage requirements of the control ends of the first switch tube Q1 and the second switch tube Q2. The voltage signal is clamped by the clamping circuit 47 and acts stably on the control ends of the first switch tube Q1 and the second switch tube Q2, triggering the first switch tube Q1 and the second switch tube Q2 to turn off, the relay 20 loses power and disconnects, and the heating tube stops working.

[0096] In one embodiment, the conversion circuit 461 may include a resistor R6, which is connected across two ends of the secondary side of the AC transformer TA to achieve conversion of the current signal into a voltage signal.

[0097] In one embodiment, the voltage divider circuit 463 may include two resistors R7 and R8 connected in series, and a connection point of the two resistors R7 and R8 is used as an output end of the voltage divider circuit 463 and connected to an input end of the clamp circuit 47 .

[0098] Optionally, a capacitor C4 may be connected between the output end of the voltage divider circuit 463 and the ground to stabilize the output signal of the voltage divider circuit 463 .

[0099] Optionally, the second filtering circuit 464 includes:

[0100] A resistor R9, wherein an input end of the resistor R9 is connected to an output end of the voltage divider circuit 463;

[0101] The capacitor C5 is connected in series between the output end of the resistor R9 and the ground, and the connection end between the capacitor C5 and the resistor R9 is connected to the clamping circuit 47 .

[0102] Optionally, the half-wave rectifier circuit can be implemented based on the diode D2.

[0103] In one embodiment, the clamp circuit 47 may include a diode D3, the anode of the diode D3 is connected to the output end of the voltage divider circuit 463, and the cathode of the diode D3 is connected to the power module 10, so as to output a stable voltage to the control end of the first switch tube Q1 and the control end of the second switch tube Q2 when the water heater leaks electricity. For example, the cathode of the diode D3 can be connected to a 5V voltage from the power module 10.

[0104] In one embodiment, the water heater protection circuit further includes:

[0105] The alarm module 50 has an input end connected to an output end of the leakage detection circuit 40 .

[0106] When the water heater has a leakage, the output end of the leakage detection circuit 40 outputs a voltage to the alarm module 50, and the alarm module 50 is powered on to work to remind the user that the water heater has a leakage.

[0107] In one embodiment, the alarm module 50 includes:

[0108] The sound alarm H has an input terminal connected to the output terminal of the leakage detection circuit 40, and the output terminal of the sound alarm H is grounded. When the water heater leaks, the leakage detection circuit 40 outputs a voltage to the input terminal of the sound alarm H, driving the sound alarm H to work, so as to remind the user that the water heater has leakage, and to pay attention to safety and handle it in time.

[0109] In one embodiment, the alarm module 50 further includes:

[0110] The resistor R5 is connected in parallel with the sound alarm H to prevent the output voltage of the leakage detection circuit 40 from being too large and burning the sound alarm H.

[0111] The sound alarm H may be a buzzer.

[0112] In one embodiment, the alarm module 50 includes:

[0113] The light emitting device LED is externally mounted on the water heater body, the input end of the light emitting device LED is connected to the output end of the leakage detection circuit 40, and the output end of the light emitting device LED is grounded. When the water heater leaks electricity, the leakage detection circuit 40 outputs a voltage to the input end of the light emitting device LED to drive the light emitting device LED to work (for example, always on or flashing), so as to remind the user that the water heater has leakage, and to pay attention to safety and handle it in time.

[0114] The light emitting device LED may be placed externally on the water heater body, including but not limited to being placed on the outer wall of the water heater body, or being embedded in the shell of the water heater body.

[0115] The light emitting device LED may be a LED (Light Emitting Diode) lamp.

[0116] In one embodiment, the alarm module 50 may include the above-mentioned sound alarm H and light emitting device LED, which are connected in series between the output terminal of the leakage detection circuit 40 and the ground. When the water heater leaks electricity, the leakage detection circuit 40 outputs a voltage to drive the sound alarm H and the light emitting device LED to work (for example, always on or flashing), and remind the user that the water heater has leakage in an audible and visual alarm manner.

[0117] In one embodiment, the power module 10 includes:

[0118] Transformer T, the primary side of transformer T is used to connect to an external power supply. For example, it can be connected to 220V AC. The high potential end of transformer T is connected to the live wire ACL, and the low potential end of transformer T is connected to the neutral wire ACN.

[0119] The rectifier bridge BRIDGE has an input end connected to the secondary side of the transformer T, and an output end of the rectifier bridge BRIDGE is respectively connected to the first end of the control coil of the relay 20 and the input end of the first switch tube Q1.

[0120] Among them, the rectifier bridge BRIDGE can adopt full-bridge rectification.

[0121] Optionally, the power module 10 also includes a capacitor C3, which is connected between the two output terminals of the rectifier bridge BRIDGE to filter the output voltage of the rectifier bridge BRIDGE. The capacitor C3 has an energy storage function and can discharge to the control coil of the relay 20 for a period of time when the external power supply suddenly fails.

[0122] The embodiment of the present application also provides a water heater, including the water heater protection circuit. The interpretation of each component in the water heater protection circuit and the realization of its functions can all be referred to the description in the above embodiment, and will not be repeated here.

[0123] The water heater provided in the embodiment of the present application is equipped with the above water heater protection circuit, and the anti-dry-burning circuit 30 and the leakage detection circuit 40 share a relay to complete leakage protection and anti-dry-burning, thereby reducing costs and simplifying the circuit. In addition, the water heater equipped with the above water heater protection circuit can effectively prevent leakage current from entering the anti-dry-burning circuit and burning the components in the anti-dry-burning circuit by providing a first switch tube and a second switch tube.

[0124] When the inner tank is a plastic inner tank, the inner tank is not connected to the metal barrel body, and is also not connected to the ground wire of the plug. At this time, the leakage detection point LD of the water heater can be the flange of the water heater.

[0125] When the inner tank of the water heater is a metal tank, the leakage detection point LD of the water heater may be a point on the inner tank.

[0126] In the description of this specification, the description with reference to the terms "some embodiments", "other embodiments", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic description of the above terms does not necessarily refer to the same embodiment or example.

[0127] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0128] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A water heater protection circuit, It is characterized in that Applied to a water heater, the water heater comprises an inner tank and a heating tube arranged in the inner tank, and the water heater protection circuit comprises: Power module (10); A relay (20) for controlling the on and off of the heating tube; An anti-dry-burning circuit (30) for detecting the water level of the inner pot; the anti-dry-burning circuit (30) comprises a control module (31), a first switch tube Q1, a first detection end (A), a second switch tube Q2 and a second detection end (B); the input end of the first switch tube Q1 is connected to the power module (10), and the output end of the first switch tube Q1 is connected to the first detection end (A); the input end of the second switch tube Q2 is connected to the second detection end (B), and the output end of the second switch tube Q2 is connected to the control module (31); the control module (31) controls the connection to the relay (20); The leakage detection circuit (40) is used to detect the leakage current of the inner container; the output end of the leakage detection circuit (40) is respectively connected to the control end of the first switch tube Q1 and the control end of the second switch tube Q2.

2. The water heater protection circuit according to claim 1, It is characterized in that The control module (31) comprises: A third switch tube Q3, wherein the output end of the third switch tube Q3 is connected to the relay (20), the control end of the third switch tube Q3 is connected to the output end of the second switch tube Q2, and the input end of the third switch tube Q3 is grounded.

3. The water heater protection circuit according to claim 2, It is characterized in that The control circuit also includes: A diode D1 is connected in parallel with the relay (20).

4. The water heater protection circuit according to claim 1, It is characterized in that The first switch tube Q1 is a PNP transistor, and / or the second switch tube Q2 is a PNP transistor.

5. The water heater protection circuit according to claim 2, It is characterized in that The third switch tube Q3 is an NPN transistor.

6. The water heater protection circuit according to claim 1, It is characterized in that The leakage detection circuit (40) comprises: A first capacitor (41) is connected in series between the leakage detection point of the inner tank and the neutral line (ACN); A bidirectional optocoupler (42), wherein an input light emitting diode of the bidirectional optocoupler (42) is connected in series with the first capacitor (41), a collector of an output transistor of the bidirectional optocoupler (42) is connected to the power module (10), and an emitter of an output transistor of the bidirectional optocoupler (42) is connected to a control end of the first switch tube Q1 and a control end of the second switch tube Q2.

7. The water heater protection circuit according to claim 6, It is characterized in that The leakage detection circuit (40) further includes: At least one first current limiting module (43), wherein the first current limiting module (43) is connected in series with the first capacitor (41).

8. The water heater protection circuit according to claim 1, It is characterized in that The leakage detection circuit (40) comprises: A second capacitor (45) is connected in series between the leakage detection point of the inner tank and the neutral line (ACN); an alternating current transformer (TA), used for sensing a leakage current passing through the second capacitor (45); A rectifier and filter circuit (46), wherein an input end of the rectifier and filter circuit (46) is connected to an output end of the AC transformer (TA); and an output end of the rectifier and filter circuit (46) is connected to a control end of the first switch tube Q1 and a control end of the second switch tube Q2; The clamping circuit (47) is connected to the output end of the rectifying and filtering circuit (46).

9. The water heater protection circuit according to any one of claims 1 to 8, It is characterized in that Also includes: An alarm module (50), wherein an input end of the alarm module (50) is connected to an output end of the leakage detection circuit (40).

10. A water heater, It is characterized in that The invention comprises a water heater protection circuit as claimed in any one of claims 1 to 9.

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