Water heater protection circuit and water heater
By sharing a relay in the water heater protection circuit to achieve anti-dry burning and leakage protection, and using the switch tube structure to simplify the circuit, the high cost problem of traditional water heaters is solved, and cost reduction and circuit reliability improvement are achieved.
Patent Information
- Application Number
- CN202410379712.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-03-29
- Publication Date
- 2025-09-30
AI Technical Summary
The anti-leakage and anti-dry-burn protection circuits of traditional water heaters require multiple relays, resulting in high costs.
A water heater protection circuit is designed. The first and second switching tubes in the anti-dry-burning circuit are combined with a leakage detection circuit to share a relay to achieve anti-dry-burning and leakage protection. By setting the first and second switching tubes, leakage current is prevented from entering the anti-dry-burning circuit, simplifying the circuit structure.
The cost of the protection circuit is reduced, and at the same time, leakage current is effectively prevented from burning out the components in the anti-dry-burning circuit, thereby improving the reliability and service life of the circuit.
Smart Images
Figure CN120720745A_ABST
Abstract
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 ease of use. Safety is crucial during their use. However, the applicant has discovered that conventional technologies require separate control circuits for leakage protection and dry-boiling protection, requiring multiple relays for control, resulting in high costs. Summary of the Invention
[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-burn 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. The water heater includes an inner tank and a heating tube disposed in the inner tank. The water heater protection circuit includes:
[0006] Power module;
[0007] Relay, used to control the power on and off of the heating tube;
[0008] The anti-dry-burn circuit is used to detect the water level in the inner tank; the anti-dry-burn circuit includes a control module, a first switch tube, a first detection terminal, a second switch tube and a second detection terminal. The input terminal of the first switch tube is connected to the power module, and the output terminal of the first switch tube is connected to the first detection terminal; the input terminal of the second switch tube is connected to the second detection terminal, and the output terminal 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, the first switch tube and the second switch tube can trigger the relay 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] The third switch tube has an output end connected to the relay, a control end of the third switch tube connected to the output end of the second switch tube, and an input end of the third switch tube connected to the ground.
[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 the voltage applied to the relay when the third switch tube is turned on can be prevented, thereby preventing the device from burning out and improving 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 powered on, the electrical signal output by the power supply 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 switching tube and the control end of the second switching tube, so that both the first switching tube and the second switching tube are 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 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, configured to sense 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 to block the DC power. 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 rectification and filtering 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 switching tube and the control end of the second switching tube, so that the first switching tube and the second switching tube are both turned off. At this time, the control coil of the relay is not energized, and the relay disconnects the path for supplying power from the power supply module to the heating tube, thereby achieving 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 remind the user that the water heater has a leakage.
[0036] In a second aspect, a water heater is provided, comprising the above-mentioned water heater protection circuit.
[0037] This water heater, equipped with the aforementioned water heater protection circuit, uses a single relay for both the dry-boil protection circuit and the leakage detection circuit, reducing costs while simplifying the circuit. Furthermore, the provision of a first switching transistor and a second switching transistor effectively prevents leakage current from entering the dry-boil protection circuit and damaging components within it. BRIEF DESCRIPTION OF THE DRAWINGS
[0038] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the conventional technology, the following briefly introduces the drawings required for use in the embodiments or the conventional technology descriptions. 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] Figure 1 This is a schematic diagram of the structure of a water heater protection circuit according to an embodiment;
[0040] Figure 2 This is a second structural 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, terminal block; 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. Rectifier filter circuit; 461. Conversion circuit; 462. Half-wave rectifier circuit; 463. Voltage divider circuit; 464. Second filter circuit; 47. Clamping circuit; 50. Alarm module. DETAILED DESCRIPTION
[0043] To facilitate understanding of the present application, the present application will be described more fully below with reference to the accompanying drawings. The accompanying drawings provide embodiments of the present application. However, the present application may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided 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 pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application.
[0045] It will be understood that the terms "first," "second," etc., used herein may be used herein to describe various elements, 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 may be referred to as a second capacitor, and similarly, a second capacitor may be referred to as a first capacitor. Both a first capacitor and a 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 there is transmission of electrical signals or data between the connected circuits, modules, units, etc.
[0047] It will be understood that "at least one" means one or more, and "a plurality of" means two or more.
[0048] As used herein, the singular forms "a," "an," and "the" may also include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "include," "comprising," "having," and the like specify the presence of stated features, integers, steps, operations, components, parts, or combinations thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, components, parts, or combinations thereof. Furthermore, the term "and / or" as 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 operating voltage required by the modules connected to it. The power module 10 can be connected to an external power source and receive an AC power signal from the external power source, such as the AC power applied 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 tank, 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 spaced apart. 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 boiling), there is no water between the first detection terminal A and the second detection terminal B, and 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. The control module 31 cannot drive the relay 20 to close. At this time, the heating tube stops heating, and anti-dry boiling 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 achieved. That is, anti-dry burning protection and leakage protection are achieved by sharing a relay 20, which reduces costs.
[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 switching tube and a second switching 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 terminal 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 is disconnected, 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 Q3 is an NPN transistor. The base of the NPN transistor serves as the control terminal of the third switch Q3, the emitter of the NPN transistor serves as the input terminal of the third switch 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 Q3. The NPN transistor is turned on when the base is connected to a high level and is turned off when the base is connected to a low level.
[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, thereby 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, the third switch tube Q3 may also be provided with some peripheral devices. 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 terminal of the second switch tube Q2 and the control terminal of the third switch tube Q3.
[0067] Capacitor C1 , a first end of the capacitor C1 is connected to the output end of the second switch tube Q2 and the control end of the third switch tube Q3 respectively, 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 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 connected in the forward direction 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] Connecting a diode D1 across the control coil prevents excessive voltage from being applied to the control coil when the third switch Q3 is turned on. This clamps the voltage applied to the control coil to near the operating voltage of the relay 20 when it is turned off, preventing component burnout and extending the service life of the control module 31. For example, in one embodiment, diode D1 can clamp the voltage applied to 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 its corresponding PNP transistor, the output end of the first switch tube Q1 is the emitter of its corresponding PNP transistor, and the control end of the first switch tube Q1 is the base of its corresponding PNP transistor.
[0075] The input terminal of the second switch tube Q2 is the collector of its corresponding PNP transistor, the output terminal of the second switch tube Q2 is the emitter of its corresponding PNP transistor, and the control terminal of the second switch tube Q2 is the base of its corresponding PNP transistor. The PNP base is disconnected when connected to a high level and is connected 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, turning off the first switch tube Q1 and the second switch tube Q2, disconnecting 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. The control coil of the relay 20 loses power, the relay 20 is disconnected, and the heating element is powered off and stops working, achieving leakage protection.
[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 terminal of the first switch tube Q1 and the control terminal of the second switch tube Q2.
[0078] When the water heater leaks, the leakage detection point LD becomes energized. The electrical signal output by the power module 10 flows through the bidirectional optocoupler 42 based on the AC-passing and DC-blocking function of the first capacitor 41. The bidirectional optocoupler 42 then conducts in both directions. The input light-emitting diode of the bidirectional optocoupler 42 illuminates, triggering the output transistor of the bidirectional optocoupler 42 to turn on. This transmits the voltage input from the power module 10 to the control terminals of the first and second switching transistors Q1 and Q2, driving both the first and second switching transistors Q1 and Q2 to turn off. This de-energizes the control coil of the relay 20, disconnects the relay 20, and de-energizes the heating element, achieving leakage protection.
[0079] The voltage applied to the collector of the output transistor of bidirectional optocoupler 42 from power module 10 must match the voltage applied to the control terminals of first and second switching transistors Q1 and Q2 to properly switch them on and off, preventing damage to them. For example, the collector of the output transistor of bidirectional optocoupler 42 can be supplied with a 5V voltage from 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 modules 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, preventing the device from burning 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 emitter of the output transistor of the bidirectional optocoupler 42 is further grounded via a capacitor C2 to filter and store energy in the electrical signal output by the emitter of the output transistor of the bidirectional optocoupler 42. The voltage output by the emitter of the output transistor of the bidirectional optocoupler 42 can be smoothly transmitted to the control terminal of the first switch Q1 and the control terminal of the second switch 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] A second capacitor 45 is connected in series between the inner tank's leakage detection point LD and the neutral line ACN. An AC transformer TA senses the leakage current passing through the second capacitor 45. The input of a rectifier and filter circuit 46 is connected to the output of the AC transformer TA. The output of the rectifier and filter circuit 46 is connected to the control terminals of the first and second switching transistors Q1 and Q2. A clamping circuit 47 is connected to the output of the rectifier and filter circuit 46.
[0088] The AC power output from the power module 10 is transmitted to the primary side of the AC transformer TA through a second capacitor 45, which blocks the DC power. When the water heater's leakage detection point LD is energized, the primary side of the AC transformer TA becomes conductive. At this point, the secondary side of the AC transformer TA outputs AC power to the rectifier and filter circuit 46. After passing through the rectifier and filter circuit 46, a DC signal is output to the control terminals of the first and second switching transistors Q1 and Q2. The clamping circuit 47 stabilizes the output of this DC signal. This DC signal drives both the first and second switching transistors Q1 and Q2 to turn off. At this point, the control coil of the relay 20 is de-energized, and the relay 20 disconnects the power supply path from the power module 10 to the heating element, achieving leakage protection.
[0089] In one embodiment, the second capacitor 45 may be a high-voltage ceramic capacitor.
[0090] In one embodiment, the rectification 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 stably acts 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 connected across 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 between 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] Resistor R9, where 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 clamping circuit 47 may include a diode D3. The anode of the diode D3 is connected to the output terminal of the voltage divider circuit 463, and the cathode of the diode D3 is connected to the power module 10. This allows the clamping circuit 47 to output a stable voltage to the control terminals of the first and second switching transistors Q1 and Q2 when the water heater experiences a leakage current. For example, the cathode of the diode D3 may 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 the output end of the leakage detection circuit 40 .
[0106] When the water heater leaks electricity, the output terminal of the leakage detection circuit 40 outputs a voltage to the alarm module 50 , and the alarm module 50 is powered on 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 operate, thereby alerting the user to the leakage and prompting safety precautions and timely handling.
[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. The input terminal of the light-emitting device LED is connected to the output terminal of the leakage detection circuit 40, and the output terminal of the light-emitting device LED is grounded. When a leakage occurs in the water heater, the leakage detection circuit 40 outputs a voltage to the input terminal of the light-emitting device LED, driving the light-emitting device LED to operate (e.g., illuminate steadily or flash), alerting the user to the leakage and urging safety precautions and prompt action.
[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 light emitting diode (LED).
[0116] In one embodiment, the alarm module 50 may include the aforementioned sound alarm H and light-emitting device LED, which are connected in series between the output terminal of the leakage detection circuit 40 and ground. When a leakage occurs in the water heater, the leakage detection circuit 40 outputs a voltage to drive the sound alarm H and light-emitting device LED to operate (e.g., to illuminate steadily or flash), alerting the user to the leakage through an audible and visual alarm.
[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 source. 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 ends 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 present application also provides a water heater including the above water heater protection circuit. The interpretation of each component of the water heater protection circuit and the implementation of its functions can 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 utilizes the aforementioned water heater protection circuit. The anti-dry-boil circuit 30 and the leakage detection circuit 40 share a single relay to implement both leakage protection and dry-boil prevention, thereby reducing costs and simplifying the circuit. Furthermore, the water heater equipped with the aforementioned water heater protection circuit, by providing a first switching transistor and a second switching transistor, effectively prevents leakage current from entering the anti-dry-boil circuit and damaging components within the circuit.
[0124] Among them, when the inner liner is a plastic liner, the inner liner is not connected to the metal barrel body, and is also not connected to the plug ground wire. In this case, 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 can be a point on the inner tank.
[0126] In the description of this specification, reference to the terms "some embodiments" or "other embodiments" 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 descriptions of the above terms do not necessarily refer to the same embodiment or example.
[0127] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned 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 merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present application. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present application, and these modifications and improvements fall within the scope of protection of the present application. Therefore, the scope of protection of the present application shall be determined by the appended claims.
Claims
1. A water heater protection circuit, characterized in that: Applied to a water heater, the water heater includes an inner tank and a heating tube arranged in the inner tank, and the water heater protection circuit includes: Power module (10); A relay (20) for controlling the on and off of the heating tube; An anti-dry-burning circuit (30) is used to detect the water level of the inner pot; the anti-dry-burning circuit (30) includes 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); A leakage detection circuit (40) is used to detect 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, 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, characterized in that: The control circuit further includes: A diode D1 is connected in parallel with the relay (20).
4. The water heater protection circuit according to claim 1, 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, characterized in that: The third switch tube Q3 is an NPN transistor.
6. The water heater protection circuit according to claim 1, 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 the 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, 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, 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 AC transformer (TA), configured to sense leakage current passing through the second capacitor (45); A rectifier and filter circuit (46), wherein the input end of the rectifier and filter circuit (46) is connected to the output end of the AC transformer (TA); 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 clamping circuit (47) is connected to the output end of the rectifier and filter circuit (46).
9. The water heater protection circuit according to any one of claims 1 to 8, 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, characterized in that: The water heater protection circuit comprises the water heater protection circuit according to any one of claims 1 to 9.