Gas valve control circuit and gas water heater

Abstract

The utility model discloses a gas valve control circuit and a gas water heater, and the gas valve control circuit comprises a fan rotating speed collection circuit which is used for collecting and outputting a fan rotating speed signal; the control module is used for receiving the fan rotating speed signal and controlling and generating a control signal output according to the fan rotating speed signal; and the gas valve driving circuit receives the fan rotating speed signal and the control signal, generates a gas valve driving signal according to the fan rotating speed signal and the control signal and outputs the gas valve driving signal. According to the gas valve control circuit, by collecting the fan rotating speed signal, on one hand, the fan rotating speed signal is utilized to generate the control signal and send the control signal to the gas valve driving circuit, and on the other hand, the fan rotating speed signal is directly sent to the gas valve driving circuit; the gas valve driving circuit generates a gas valve control signal under the common control of the two paths of signals, and when any path is abnormal, the gas valve cannot be normally opened, so that the safety and the reliability of opening control of the gas valve are improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of water heaters, and in particular relates to a gas valve control circuit and a gas water heater. Background Art

[0002] With the development of electronic technology and Internet technology, the degree of intelligence of household appliances is getting higher and higher, the market share of gas water heaters is getting larger and larger, and energy-saving DC variable frequency gas water heaters are becoming more and more popular among consumers. At present, the gas channel of gas water heaters on the market adopts a double-valve control method, and the control board outputs a control signal to realize opening and closing. If the control board that controls the gas circuit is abnormal, the two solenoid valves are opened at the same time, which will cause continuous gas leakage. The control board cannot close the solenoid valve, which may cause gas leakage into the user's room, causing carbon monoxide poisoning or causing gas combustion and explosion, posing a threat to the user's property and even life.

[0003] The above information disclosed in the background technology is only used to increase the understanding of the background technology of the present application, and therefore, it may include information that does not constitute the prior art known to ordinary technicians in the field. Summary of the invention

[0004] The utility model aims at the technical problem that the opening of the gas valve in the prior art depends on program control and has high safety risks, and proposes a gas valve control circuit to solve the above problem.

[0005] In order to achieve the above-mentioned utility model purpose, the utility model adopts the following technical solutions:

[0006] A gas valve control circuit, comprising:

[0007] A fan speed acquisition circuit is used to acquire and output the fan speed signal;

[0008] A control module receives the fan speed signal and generates a control signal output according to the fan speed signal;

[0009] The gas valve driving circuit receives the fan speed signal and the control signal, generates and outputs a gas valve driving signal according to the fan speed signal and the control signal.

[0010] In some embodiments, the gas valve drive circuit includes a first switch circuit, a second switch circuit and a drive signal generating circuit, the first switch circuit and the second switch circuit are connected in series, and one end of the series circuit is connected to a DC power supply, and the other end is connected to the drive signal generating circuit and a ground end in sequence:

[0011] The control end of the first switch circuit receives the control signal, and its on-off state is controlled by the control signal;

[0012] The control end of the second switch circuit receives the fan speed signal, and its on-off state is controlled by the fan speed signal;

[0013] The driving signal generating circuit generates and outputs a gas valve driving signal according to the on / off states of the first switching circuit and the second switching circuit.

[0014] In some embodiments, the first switch circuit includes:

[0015] A first NPN transistor, wherein the base of the first NPN transistor is connected to the control signal output terminal of the control module;

[0016] A first PNP transistor, wherein the base of the first PNP transistor is connected to the collector of the first NPN transistor, the emitter of the first PNP transistor is connected to a DC power supply, and the collector of the first PNP transistor is connected to the second switch circuit.

[0017] In some embodiments, the second switch circuit includes:

[0018] A second NPN transistor, wherein the base of the second NPN transistor is connected to the output end of the fan speed collection circuit;

[0019] A second PNP transistor, wherein the base of the second PNP transistor is connected to the collector of the second NPN transistor, the emitter of the second PNP transistor is connected to the collector of the first PNP transistor, and the collector of the second PNP transistor is connected to the drive signal generating circuit.

[0020] In some embodiments, the drive signal generating circuit includes a third diode, the anode of the third diode is connected to the ground, the cathode is connected to the collector of the second PNP transistor, and the signal output end of the drive signal generating circuit is respectively connected to the two ends of the third diode.

[0021] In some embodiments, the second switch circuit further includes:

[0022] A second isolation circuit, connected between the base of the second NPN transistor and the output end of the fan speed acquisition circuit, for isolating a DC level signal;

[0023] The second isolation circuit comprises:

[0024] a second electrolytic capacitor, a positive electrode of which is connected to the output end of the fan speed acquisition circuit, and a negative electrode of which is connected to the base of the second NPN transistor through an eleventh resistor;

[0025] a second diode, one end of which is connected between the eleventh resistor and the base of the second NPN transistor, and the other end of which is connected to the ground;

[0026] A tenth resistor, one end of which is connected between the output end of the fan speed acquisition circuit and the second electrolytic capacitor, and the other end of which is connected to the ground.

[0027] In some embodiments, the first switch circuit further includes:

[0028] A first isolation circuit, connected between the base of the first NPN transistor and the control signal output terminal of the control module, for isolating a DC level signal;

[0029] The first isolation circuit comprises:

[0030] a first electrolytic capacitor, a positive electrode of which is connected to the control signal output terminal of the control module, and a negative electrode of which is connected to the base of the first NPN transistor through a sixth resistor;

[0031] a first diode, one end of which is connected between the sixth resistor and the base of the first NPN transistor, and the other end of which is connected to the ground;

[0032] A fifth resistor has one end connected between the control signal output end of the control module and the first electrolytic capacitor, and the other end connected to the ground.

[0033] In some embodiments, the fan speed acquisition circuit includes:

[0034] Hall detection module;

[0035] A third NPN transistor, wherein the base of the third NPN transistor is connected to the output end of the Hall detection module, and the collector of the third NPN transistor is connected to the control module via a fourth resistor.

[0036] In some embodiments, the control module includes a timer, and the timer interrupt generates and outputs the control signal.

[0037] The utility model also provides a gas water heater, which comprises a fan and a gas valve, and also comprises the gas valve control circuit described in any one of the above items.

[0038] Compared with the prior art, the advantages and positive effects of the utility model are:

[0039] The gas valve control circuit of the utility model collects the fan speed signal, and on the one hand, uses the fan speed signal to generate a control signal and sends it to the gas valve drive circuit, and on the other hand, the fan speed signal is directly sent to the gas valve drive circuit, and the gas valve drive circuit generates a gas valve control signal under the common control of the above two signals. When any one of the two signals is abnormal, the gas valve cannot be opened normally, thereby improving the safety and reliability of the opening control of the gas valve.

[0040] After reading the specific embodiments of the present invention in conjunction with the accompanying drawings, other features and advantages of the present invention will become more clear. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, a brief introduction will be given below to the drawings required for use in the embodiments. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0042] Figure 1 It is a principle block diagram of an embodiment of the gas valve control circuit proposed by the utility model;

[0043] Figure 2 It is a principle block diagram of a gas valve driving circuit in one embodiment of a gas valve control circuit proposed by the utility model;

[0044] Figure 3 This is a circuit schematic diagram of an embodiment of the gas valve control circuit proposed by the utility model;

[0045] Figure 4 The utility model discloses a circuit schematic diagram of a fan speed acquisition circuit in one embodiment of a gas valve control circuit. DETAILED DESCRIPTION

[0046] In order to make the purpose, technical solution and advantages of the embodiment of the utility model clearer, the technical solution in the embodiment of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiment of the utility model. Obviously, the described embodiment is a part of the embodiment of the utility model, not all of the embodiments. Based on the embodiment of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0047] It should be noted that, in the description of the present invention, the terms "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside" and the like indicating directions or positional relationships are based on the directions or positional relationships shown in the drawings, which are merely for the convenience of description, and do not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance. In the description of the present invention, "multiple" means two or more, unless otherwise clearly and specifically defined.

[0048] In the present invention, unless otherwise clearly specified and limited, the terms "install", "connect", "connect", "fix" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0049] The circuit for controlling the gas valve in the gas equipment generally adopts a single MCU control method. When the MCU fails or the device in the control loop is abnormal, the gas valve driver chip will be damaged, causing the gas valve to open, which can turn on the gas valve switch and cause gas leakage, which is very dangerous.

[0050] Embodiment 1: This embodiment proposes a gas valve control circuit, such as Figure 1 As shown, it includes a fan speed acquisition circuit, which is used to collect and output the fan speed signal. When the user uses water, the gas water heater detects the water flow signal, first turns on the fan for front cleaning, and discharges the exhaust gas in the water heater through the smoke pipe. After the wind pressure switch detects that it is closed, it opens the gas valve, ignites, and then burns. After the water is heated, it flows out through the water heater. The fan speed signal is directly collected and output by the hardware circuit.

[0051] The gas valve control circuit also includes a control module, which can receive a fan speed signal and generate a control signal output according to the fan speed signal. The control signal is generated and output after logical judgment by the control module.

[0052] The control signal is used to control the switch of the gas valve. It can be understood that the gas valve can be controlled to open only after the fan is turned on. Otherwise, if the fan is not turned, the gas valve will not be controlled to open.

[0053] The gas valve control circuit also includes a gas valve drive circuit, which receives a fan speed signal and a control signal, generates and outputs a gas valve drive signal according to the fan speed signal and the control signal. The gas valve drive signal is used to directly control the opening or closing of the gas valve.

[0054] The gas valve control circuit of this embodiment collects the fan speed signal. On the one hand, it uses the fan speed signal to generate a control signal and sends it to the gas valve drive circuit. On the other hand, the fan speed signal is directly sent to the gas valve drive circuit. The gas valve drive circuit generates a gas valve control signal under the joint control of the above two signals. When any one of the two signals is abnormal, the gas valve cannot be opened normally, thereby improving the safety and reliability of the opening control of the gas valve.

[0055] In some embodiments, the control module may be implemented using, but not limited to, an MCU.

[0056] In some embodiments, such as Figure 2 As shown, the gas valve driving circuit includes a first switch circuit, a second switch circuit and a driving signal generating circuit. The first switch circuit and the second switch circuit are connected in series, and one end of the series circuit is connected to a DC power supply Vcc, and the other end is connected to the driving signal generating circuit and the ground in sequence. The on-off state of the first switch circuit and the second switch circuit can control whether the driving signal generating circuit generates a gas valve control signal or not.

[0057] The control end of the first switch circuit is connected to the control module and can receive a control signal sent by the control module. The on-off state of the first switch circuit is controlled by the control signal.

[0058] The control end of the second switch circuit is connected to the fan speed acquisition circuit and can receive the fan speed signal sent by the fan speed acquisition circuit. The on-off state of the second switch circuit is controlled by the fan speed signal.

[0059] The driving signal generating circuit generates and outputs a gas valve driving signal according to the on / off states of the first switching circuit and the second switching circuit.

[0060] In some embodiments, such as Figure 3 As shown, the first switch circuit includes a first NPN transistor N1, the base of the first NPN transistor N1 is connected to the control signal output end of the control module, and receives the control signal Mcu_Hz sent by the control module.

[0061] The first switch circuit also includes a first PNP transistor P1, a base of the first PNP transistor P1 is connected to a collector of the first NPN transistor N1, an emitter of the first PNP transistor P1 is connected to a DC power supply Vcc, and a collector of the first PNP transistor P1 is connected to the second switch circuit.

[0062] The control signal Mcu_Hz is used to drive the first NPN transistor N1. When the control signal Mcu_Hz outputs a high level, the first NPN transistor N1 is turned on, and the base level of the first PNP transistor P1 is pulled down, and the first PNP transistor P1 is turned on accordingly.

[0063] In some embodiments, such as Figure 3 As shown, the second switch circuit includes a second NPN transistor N2, and the base of the second NPN transistor N2 is connected to the output end of the fan speed acquisition circuit. The base of the second NPN transistor N2 can receive the fan speed signal PG sent by the fan speed acquisition circuit. The on-off state of the second NPN transistor N2 is controlled by the fan speed signal PG.

[0064] The second switch circuit also includes a second PNP transistor P2, the base of the second PNP transistor P2 is connected to the collector of the second NPN transistor P2, the emitter of the second PNP transistor P2 is connected to the collector of the first PNP transistor P1, and the collector of the second PNP transistor P2 is connected to the drive signal generating circuit.

[0065] When the first PNP transistor P1 is turned on, the emitter of the second PNP transistor P2 is at a high level. If the fan speed signal PG is at a high level at this time, the second NPN transistor N2 is turned on, and the base level of the second PNP transistor P2 is pulled down, and the second PNP transistor P2 is turned on accordingly.

[0066] The gas valve will only open when the first PNP transistor P1 and the second PNP transistor P2 are turned on at the same time, that is, the fan speed signal and the control signal are normal. This circuit ensures from a hardware perspective that the gas valve can only be opened when the fan is operating normally. At the same time, if a single transistor has an abnormality, the system can still be kept in a safe state, thereby improving the safety of gas valve control.

[0067] In some embodiments, the drive signal generating circuit includes a third diode D3, the anode of the third diode D3 is connected to the ground, the cathode is connected to the collector of the second PNP transistor P2, and the signal output end of the drive signal generating circuit is respectively connected to the two ends of the third diode D3.

[0068] When the first PNP transistor P1 and the second PNP transistor P2 are turned on at the same time, the driving signal output by the cathode of the third diode D3 is at a high level. Otherwise, the driving signal output by the cathode of the third diode D3 is at a low level.

[0069] In some embodiments, the fan speed signal PG is a high-low level alternating signal. In order to prevent the fan speed signal PG from being abnormal, such as the fan speed signal PG is continuously at a high level, causing the second NPN transistor N2 to be in a normally-on state, which may cause the drive signal generation circuit to abnormally keep the gas valve always open. Therefore, in some embodiments, the second switch circuit further includes a second isolation circuit, which is connected between the base of the second NPN transistor N2 and the output end of the fan speed acquisition circuit to isolate the DC level signal.

[0070] Through this setting, it is possible to isolate the situation that no matter whether the fan speed signal PG is continuously at a high level or continuously at a low level, it will not cause the second NPN transistor N2 to be in a normally-on state.

[0071] In some embodiments, in order to isolate the DC signal, the high and low level alternating signals of the fan speed signal PG can effectively control the on and off of the gas valve. As shown in the figure, the second isolation circuit includes a second electrolytic capacitor E2, and the positive electrode of the second electrolytic capacitor E2 is connected to the output end of the fan speed acquisition circuit, and the negative electrode is connected to the base of the second NPN transistor N2 through the eleventh resistor R11.

[0072] In some embodiments, the second isolation circuit further includes a second diode D2 , one end of which is connected between the eleventh resistor R11 and the base of the second NPN transistor N2 , and the other end of which is connected to the ground.

[0073] When the fan speed signal PG is output at a high level, the second electrolytic capacitor E2 is charged. Since the second diode D2 is unidirectionally conducted, the second diode D2 is cut off during charging. At this time, the base of the second NPN transistor N2 is at a high level, and the second NPN transistor N2 is turned on. If the first PNP transistor P1 is turned on at this time, and then the second PNP transistor P2 is turned on, the gas valve drive circuit outputs a high level signal.

[0074] In some embodiments, the second isolation circuit further includes a tenth resistor R10, one end of the tenth resistor R10 is connected between the output end of the fan speed acquisition circuit and the second electrolytic capacitor E2, and the other end is connected to the ground.

[0075] When the fan speed signal PG output jumps from high level to low level, the second electrolytic capacitor E2 discharges, and discharges through the tenth resistor R10, the second diode D2 and the eleventh resistor R11 in sequence. Due to the voltage drop of the second diode D2, the base of the second NPN transistor N2 is still high level at this time, and the second NPN transistor N2 is turned on. If the first PNP transistor P1 is turned on at this time, and then the second PNP transistor P2 is turned on, the gas valve drive circuit outputs a high level signal, and the gas valve is opened.

[0076] If the fan speed signal PG continues to be a high level signal, after the second electrolytic capacitor E2 is fully charged, the base of the second NPN transistor N2 is pulled low, so the second NPN transistor N2 is not conducting, and the gas valve drive circuit outputs a low level signal, and the gas valve is closed.

[0077] If the fan speed signal PG continues to be a low level signal, after the second electrolytic capacitor E2 is discharged, the base of the second NPN transistor N2 is pulled low, so the second NPN transistor N2 is not conducting. At this time, the gas valve drive circuit outputs a low level signal and the gas valve is closed.

[0078] In some embodiments, the control signal Mcu_Hz is a square wave signal. In order to prevent the first NPN transistor N1 from being in a normally-on state when the control signal Mcu_Hz is abnormal, such as the control signal Mcu_Hz continuously being at a high level, there is a risk of causing the drive signal generation circuit to abnormally keep the gas valve always open. Therefore, in some embodiments, the first switch circuit also includes a first isolation circuit, which is connected between the base of the first NPN transistor and the control signal output terminal of the control module to isolate the DC level signal. Through this setting, it is possible to isolate the first NPN transistor N1 from being in a normally-on state regardless of whether the control signal Mcu_Hz is continuously at a high level or continuously at a low level.

[0079] In some embodiments, in order to isolate the DC signal, such as Figure 3 As shown, the first isolation circuit includes a first electrolytic capacitor E1, a positive electrode of the first electrolytic capacitor E1 is connected to the control signal output end of the control module, and a negative electrode is connected to the base of the first NPN transistor N1 through a sixth resistor R6.

[0080] The first isolation circuit further includes a first diode D1 , one end of which is connected between the sixth resistor R6 and the base of the first NPN transistor N1 , and the other end of which is connected to the ground.

[0081] The first isolation circuit further includes a fifth resistor R5 , one end of which is connected between the control signal output end of the control module and the first electrolytic capacitor, and the other end of which is connected to the ground.

[0082] When the control signal Mcu_Hz is output at a high level, the first electrolytic capacitor E1 is charged. Since the first diode D2 is unidirectionally conducted, the first diode D1 is cut off when the first electrolytic capacitor E1 is charged. At this time, the base of the first NPN transistor N1 is at a high level, the first NPN transistor N1 is turned on, and the base level of the first PNP transistor P1 is pulled down, and the first PNP transistor P1 is turned on.

[0083] When the control signal Mcu_Hz output jumps from high level to low level, the first electrolytic capacitor E1 discharges, and discharges through the fifth resistor R5, the first diode D1 and the sixth resistor R6 in sequence. Due to the voltage drop of the first diode D1, the base of the first NPN transistor N1 is still at a high level at this time, and the first NPN transistor N1 is turned on. The corresponding first PNP transistor P1 is turned on.

[0084] If the fan speed signal PG continues to be a high level signal, after the first electrolytic capacitor E1 is fully charged, the base of the first NPN transistor N1 is pulled low, so the first NPN transistor N1 is not conducting, and the corresponding first PNP transistor P1 is not conducting. At this time, the gas valve drive circuit outputs a low level signal, and the gas valve is closed.

[0085] If the fan speed signal PG continues to be a low level signal, after the first electrolytic capacitor E1 is fully discharged, the base of the first NPN transistor N1 is pulled low, so the first NPN transistor N1 is not conducting, and the corresponding first PNP transistor P1 is not conducting. At this time, the gas valve drive circuit outputs a low level signal, and the gas valve is closed.

[0086] In some embodiments, the fan speed acquisition circuit includes a Hall detection module, which is used to detect the rotation of the fan.

[0087] like Figure 4 As shown, the fan speed acquisition circuit also includes a third NPN transistor N3, the base of the third NPN transistor N3 is connected to the output end of the Hall detection module, and the collector of the third NPN transistor N3 is connected to the control module through a fourth resistor R4.

[0088] FG is the fan speed signal output by the Hall detection module, which drives the third NPN transistor N3 to obtain the corresponding level at the MCU port.

[0089] When the fan speed signal FG is at a high level, the third NPN transistor N3 is turned on, and the MCU pin detects a low level.

[0090] When the fan speed signal FG is at a low level, the third NPN transistor N3 is not conducting, and the MCU pin detects a high level.

[0091] In some embodiments, the control module includes a timer, and the timer interrupt generates and outputs a control signal. The MCU_Hz square wave signal cannot be generated using the PWM module, because when the PWM module fails, the PWM module is not controlled by the program, which will cause the gas valve to open by mistake. In this embodiment, the MCU_Hz square wave signal is generated by the MCU through the timer interrupt. The software ensures that the gas valve can only be opened when the timer interrupt, the main program and the fan speed are all running normally, thereby improving the safety of the gas valve control.

[0092] Embodiment 2: The utility model also proposes a gas water heater, which includes a fan and a gas valve, and also includes a gas valve control circuit.

[0093] The details of the gas valve control circuit can be found in the first embodiment, which will not be described in detail here.

[0094] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the above embodiments, it is still possible for a person skilled in the art to modify the technical solutions described in the above embodiments, or to replace some of the technical features therein with equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions claimed to be protected by the present invention.

Claims

1. A gas valve control circuit, characterized in that: include: A fan speed acquisition circuit is used to acquire and output the fan speed signal; A control module receives the fan speed signal and generates a control signal output according to the fan speed signal; The gas valve driving circuit receives the fan speed signal and the control signal, generates and outputs a gas valve driving signal according to the fan speed signal and the control signal.

2. The gas valve control circuit according to claim 1, characterized in that: The gas valve driving circuit comprises a first switch circuit, a second switch circuit and a driving signal generating circuit, wherein the first switch circuit and the second switch circuit are connected in series, and one end of the series circuit is connected to a DC power supply, and the other end is connected to the driving signal generating circuit and a ground end in sequence: The control end of the first switch circuit receives the control signal, and its on-off state is controlled by the control signal; The control end of the second switch circuit receives the fan speed signal, and its on-off state is controlled by the fan speed signal; The driving signal generating circuit generates and outputs a gas valve driving signal according to the on / off states of the first switching circuit and the second switching circuit.

3. The gas valve control circuit according to claim 2, characterized in that: The first switch circuit comprises: A first NPN transistor, wherein the base of the first NPN transistor is connected to the control signal output terminal of the control module; A first PNP transistor, wherein the base of the first PNP transistor is connected to the collector of the first NPN transistor, the emitter of the first PNP transistor is connected to a DC power supply, and the collector of the first PNP transistor is connected to the second switch circuit.

4. The gas valve control circuit according to claim 3, characterized in that: The second switch circuit comprises: A second NPN transistor, wherein the base of the second NPN transistor is connected to the output end of the fan speed collection circuit; A second PNP transistor, wherein the base of the second PNP transistor is connected to the collector of the second NPN transistor, the emitter of the second PNP transistor is connected to the collector of the first PNP transistor, and the collector of the second PNP transistor is connected to the drive signal generating circuit.

5. The gas valve control circuit according to claim 4, characterized in that: The driving signal generating circuit comprises a third diode, the anode of the third diode is connected to the ground, the cathode is connected to the collector of the second PNP transistor, and the signal output end of the driving signal generating circuit is respectively connected to the two ends of the third diode.

6. The gas valve control circuit according to claim 4, characterized in that: The second switch circuit further includes: A second isolation circuit, connected between the base of the second NPN transistor and the output end of the fan speed acquisition circuit, for isolating a DC level signal; The second isolation circuit comprises: a second electrolytic capacitor, a positive electrode of which is connected to the output end of the fan speed acquisition circuit, and a negative electrode of which is connected to the base of the second NPN transistor through an eleventh resistor; a second diode, one end of which is connected between the eleventh resistor and the base of the second NPN transistor, and the other end of which is connected to the ground; A tenth resistor, one end of which is connected between the output end of the fan speed acquisition circuit and the second electrolytic capacitor, and the other end of which is connected to the ground.

7. The gas valve control circuit according to any one of claims 3 to 6, characterized in that: The first switch circuit further includes: A first isolation circuit, connected between the base of the first NPN transistor and the control signal output terminal of the control module, for isolating a DC level signal; The first isolation circuit comprises: a first electrolytic capacitor, a positive electrode of which is connected to the control signal output terminal of the control module, and a negative electrode of which is connected to the base of the first NPN transistor through a sixth resistor; a first diode, one end of which is connected between the sixth resistor and the base of the first NPN transistor, and the other end of which is connected to the ground; A fifth resistor has one end connected between the control signal output end of the control module and the first electrolytic capacitor, and the other end connected to the ground.

8. The gas valve control circuit according to any one of claims 1 to 6, characterized in that: The fan speed acquisition circuit comprises: Hall detection module; A third NPN transistor, wherein the base of the third NPN transistor is connected to the output end of the Hall detection module, and the collector of the third NPN transistor is connected to the control module via a fourth resistor.

9. The gas valve control circuit according to any one of claims 1 to 6, characterized in that: The control module includes a timer, and the timer interrupt generates and outputs the control signal.

10. A gas water heater, comprising a fan and a gas valve, characterized in that: It also includes the gas valve control circuit according to any one of claims 1-9.

Images