A gas water heater and a control method thereof

Abstract

The application discloses a gas water heater and a control method thereof, which comprises the following steps: S1, obtaining an ignition command; S2, detecting and storing a flame current initial value I0; S3, discharging and igniting an igniter, opening a gas valve, detecting a flame current value I1 in real time, and obtaining a difference value AI=I1-I0; S4, judging whether the opening time AT is less than a first set time Tset1, if yes, executing step S5, and executing step S6; S5, judging whether the difference value AI is greater than a first current set value Iset1, if yes, outputting a flame signal, judging whether the difference value AI is less than a second current set value Iset2, if yes, outputting no flame signal; S6, judging whether the difference value AI is greater than a third current set value Iset3, if yes, outputting the flame signal, judging whether the difference value AI is less than a fourth current set value Iset4, if yes, outputting no flame signal; wherein, Iset1=Iset2+I 回差1 , Iset3=Iset4+I 回差2 ; Iset3 is greater than Iset1; and Iset4 is greater than Iset2. The application can adapt to the change of environment to judge the presence or absence of the flame signal.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of gas equipment, and particularly relates to a gas water heater and a control method thereof. BACKGROUND

[0002] Because the flame ion current after the ignition and combustion of the gas water heater is very weak, the judgment of the presence or absence of the flame is between zero and two microamperes. Therefore, the detection circuit must have and maintain a very high input resistance, including in a relatively high humidity and low temperature environment.

[0003] The high-value resistor of the related circuit on the PCB of the water heater is in a bare state, and the equivalent resistance value decreases under high humidity, resulting in value drift. When there is a flame, the flame cannot be detected, or when there is no flame, the flame is judged to be present. Therefore, in humid weather, especially in the plum rain weather in the south, users often complain that the machine cannot be ignited and works, resulting in poor user experience.

[0004] Therefore, the present application is proposed. SUMMARY

[0005] The technical problem to be solved by the present application is to overcome the shortcomings of the prior art and provide a gas water heater control method. The method obtains the parasitic basic flame value of the flame detection circuit before the valve is opened, which is equivalent to learning the environmental humidity, temperature and whether the sensing needle is scaled. The true value of the flame detection is obtained after the valve is opened, and the difference value is processed. Even when the flame burning state is not good, there will be a small change value, and the real flame can be accurately detected. Moreover, the flame is detected twice by different preset values, and the current set value after the valve is opened is higher than that before the valve is opened. The detection of the flame has double protection, and the judgment is accurate and has high precision.

[0006] To solve the above technical problems, the basic idea of the technical solution of the present application is:

[0007] A gas water heater control method, comprising the following steps:

[0008] S1, obtaining an ignition command;

[0009] S2, detecting and storing the initial flame current value I0 in the flame detection circuit at the current time;

[0010] S3, controlling the ignition device to discharge and ignite, opening the gas valve, and detecting the flame current value I1 in real time to obtain the difference value AI=I1-I0;

[0011] S4, obtaining the time difference AT between the time when the flame current value I1 in the real-time detecting flame detecting circuit is detected and the time when the igniter is ignited, judging whether AT is less than the first set time Tset1, if yes, executing step S5, if no, executing step S6;

[0012] S5, judging whether the difference AI is greater than the first current set value Iset1, if yes, controlling the flame detecting circuit to output the signal of having flame, judging whether the difference AI is less than the second current set value Iset2, if yes, controlling the flame detecting circuit to output the signal of not having flame;

[0013] S6, judging whether the difference AI is greater than the third current set value Iset3, if yes, controlling the flame detecting circuit to output the signal of having flame, judging whether the difference AI is less than the fourth current set value Iset4, if yes, controlling the flame detecting circuit to output the signal of not having flame;

[0014] Wherein, Iset1=Iset2+I 回差1 , Iset3=Iset4+I 回差2 ;

[0015] Iset3 is greater than Iset1; Iset4 is greater than Iset2.

[0016] Further, step S4 further comprises:

[0017] judging whether AT is less than the second set time Tset2, if yes, judging whether the flame current value I1 in the flame detecting circuit is less than the fifth current set value Iset5, if yes, controlling the burner to operate at the ignition power;

[0018] Wherein, Tset2=(1 / 3~1 / 2)Tset1.

[0019] Further, step S5 and step S6 further comprise:

[0020] After controlling the flame detecting circuit to output the signal of having flame, judging whether the flame current value I1 in the flame detecting circuit is greater than the sixth current set value Iset6, if yes, judging whether the duration that the flame current value I1 in the flame detecting circuit is greater than the sixth current set value Iset6 is greater than the third set time Tset3, if yes, controlling the burner and the gas valve to be closed.

[0021] Further, step S5 and step S6 further comprise:

[0022] After controlling the flame detecting circuit to output the signal of not having flame, controlling the igniter to discharge and ignite again.

[0023] Further, step S5 and step S6 further comprise:

[0024] If the number of times of the igniter discharging ignition again exceeds the predetermined number of times, the alarm is controlled to send a warning signal.

[0025] Further, between the step S1 and the step S2, there is further included a step A1:

[0026] The fan is controlled to start, and the flame current value I0 in the flame detection circuit is obtained, and it is judged whether the flame current value I0 at the current time is greater than the seventh current setting value Iset7, if yes, it is judged whether the duration that the flame current value I0 at the current time is greater than the seventh current setting value Iset7 is greater than the fourth setting time Tset4, if yes, the step S2 is executed, if no, the alarm is controlled to send a warning signal.

[0027] Further, in the step S5, it is judged whether the difference value △I is greater than the first current setting value Iset1, if yes, it is judged whether the duration that the difference value △I is greater than the first current setting value Iset1 is greater than the fifth setting time Tset5, if yes, the signal that there is flame is outputted by the flame detection circuit; it is judged whether the difference value △I is less than the second current setting value Iset2, if yes, it is judged whether the duration that the difference value △I is less than the second current setting value Iset2 is greater than the sixth setting time Tset6, if yes, the signal that there is no flame is outputted by the flame detection circuit.

[0028] Preferably, Tset5 takes 0.5s-0.8s, and Tset6 takes 0.5s-0.8s.

[0029] Further, in the step S6, it is judged whether the difference value △I is greater than the third current setting value Iset3, if yes, it is judged whether the duration that the difference value △I is greater than the third current setting value Iset3 is greater than the seventh setting time Tset7, if yes, the signal that there is flame is outputted by the flame detection circuit; it is judged whether the difference value △I is less than the fourth current setting value Iset4, if yes, it is judged whether the duration that the difference value △I is less than the fourth current setting value Iset4 is greater than the eighth setting time Tset8, if yes, the signal that there is no flame is outputted by the flame detection circuit.

[0030] Preferably, Tset7 takes 0.5s-0.8s, and Tset8 takes 0.5s-0.8s.

[0031] Further, I 回差1 takes 0.2-0.4; I 回差2 takes 0.2-0.4.

[0032] A gas water heater adopts the control method as described above.

[0033] Compared with the prior art, the present application has the following beneficial effects.

[0034] 1. The present application uses the flame current value in the flame detection circuit when the ignition command is received as the comparison value for judging whether there is flame, so that the comparison value is a comparison value that changes with the environment. Compared with the prior art in which the limit value for judging whether there is flame is a fixed value, the situation that the burner itself has no flame but the main control board detects a flame signal does not occur.

[0035] 2. The present application acquires the parasitic basic flame value of the flame detection circuit before the valve is opened, which is equivalent to learning the environmental humidity, temperature and whether the sensing needle is scaled. After the valve is opened, the true value of the flame current in the flame detection circuit is taken, and difference processing is performed with the initial value of the flame current. Therefore, even when the flame burning state is not good, small changes can be captured, and the real flame can be accurately detected.

[0036] 3. According to the length of time from the moment of controlling the igniter to ignite, the present application judges the flame at least twice, and detects the flame by using two different set values. The current set value after the first one is higher, so that the detection of the flame has double protection, and the judgment is accurate and has high precision.

[0037] The specific embodiments of the present application will be described in further detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0038] The accompanying drawings, which are part of the present application, serve to provide a further understanding of the present application, and the schematic embodiments of the present application and their descriptions serve to explain the present application, but do not constitute an improper limitation on the present application. Obviously, the accompanying drawings in the following description are only some embodiments, and other drawings can be obtained by those skilled in the art without any creative labor on the basis of these drawings. In the drawings:

[0039] Fig. 1 is a flowchart of the control method of the gas water heater in some embodiments of the present application;

[0040] Fig. 2 is a flowchart of the control method of the gas water heater in some embodiments of the present application;

[0041] Fig. 3 is a flowchart of the control method of the gas water heater in some embodiments of the present application.

[0042] It should be noted that these drawings and written descriptions are not intended to limit the scope of the concept of the present application in any way, but to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0043] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the following will clearly and completely describe the technical solutions in the embodiments with reference to the drawings in the embodiments of the present application. The following embodiments are used to explain the present application, but are not used to limit the scope of the present application.

[0044] In the description of the present application, it should be noted that the orientations or positional relationships indicated by the terms "upper", "lower", "front", "back", "left", "right", "vertical", "inner", "outer" and the like are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0045] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "installation", "connection", "connection" should be understood in a broad sense, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0046] As shown in Figs. 1 to 3 The present application provides a gas water heater and a control method thereof. In detail, the gas water heater generally includes a main control board, a water flow sensor, an igniter, a burner, a fan, a gas valve and the like. The main control board is a computer board MCU for overall control of the operation of the gas water heater. When a user uses the gas water heater, the water flow sensor detects water flow information and feeds back the water flow information to the main control board. After receiving the water flow information, the main control board controls the discharge of the igniter and the opening of the gas valve to complete the ignition work.

[0047] Generally, during the operation of the gas water heater, the state of the flame needs to be monitored to avoid abnormal extinguishing of the flame during normal operation, causing dangerous situations such as gas leakage.

[0048] The flame has two major characteristics: ionization and unidirectional conductivity. Ionization refers to the weak conductivity of the flame, which is generally equivalent to 1M to 10M ohms. However, if dust or oil stains fall between the burner and the detection probe, there will also be resistance, which is easy to misjudge as having a flame, so the ionization of the flame is generally not used as a criterion for determining the presence or absence of a flame. Unidirectional conductivity is a characteristic of the flame that is the same as that of a diode - unidirectional conductivity, so the unidirectional conductivity of the flame can be used to determine whether there is a flame, and as a prerequisite for subsequent control of other components of the water heater.

[0049] Specifically, as shown in Fig. 1 the gas water heater control method comprises the following steps:

[0050] S1, obtaining an ignition command;

[0051] S2, detecting and storing a current initial flame current value I0 in the flame detection circuit;

[0052] S3, controlling the igniter to discharge ignition and the gas valve to open, detecting a real-time flame current value I1, and obtaining a difference value ΔI = I1 - I0;

[0053] S4, obtaining a time difference value ΔT between the time when the real-time flame current value I1 in the flame detection circuit is detected and the time when the igniter is controlled to ignite, and determining whether the time difference value ΔT is less than a first set time Tset1, if yes, executing step S5, and if no, executing step S6;

[0054] S5, determining whether the difference value ΔI is greater than a first current set value Iset1, if yes, controlling the flame detection circuit to output a signal indicating that there is flame, and determining whether the difference value ΔI is less than a second current set value Iset2, if yes, controlling the flame detection circuit to output a signal indicating that there is no flame;

[0055] S6, determining whether the difference value ΔI is greater than a third current set value Iset3, if yes, controlling the flame detection circuit to output a signal indicating that there is flame, and determining whether the difference value ΔI is less than a fourth current set value Iset4, if yes, controlling the flame detection circuit to output a signal indicating that there is no flame;

[0056] wherein Iset1 = Iset2 + I 回差1 , Iset3 = Iset4 + I 回差2 ;

[0057] Iset3 is greater than Iset1, and Iset4 is greater than Iset2.

[0058] It should be noted that the detection of the flame can also be divided into multiple stages according to time. The present application only describes two stages in detail.

[0059] In the above determination of whether the burner has flame, the present application detects the initial flame current value I0 in the flame detection circuit at the current time when the main control board receives the ignition command, and saves the initial flame current value I0 at the current time as a basis for determining whether the ignition is successful.

[0060] That is, the parasitic basic flame value of the flame detection circuit is obtained before the valve is opened, which is equivalent to learning the environmental humidity, temperature and whether the sensing needle is scaled, and the true value of the flame current in the flame detection circuit is obtained after the valve is opened, and the difference between the true value and the initial value of the flame current is processed, so that even when the flame burning state is not good, small changes can also be captured, and the real flame can be accurately detected. In addition, according to the length of time from the time when the control point igniter is ignited, the present application judges the flame at least twice, and detects the flame by using two different set values, and the current set value after the current set value is higher, so that the detection of the flame has double protection, the judgment is accurate, and the precision is high.

[0061] In the above scheme, since the flame current value in the flame detection circuit of the gas water heater is different due to different environments of the gas water heater, the present application uses the flame current value in the flame detection circuit when receiving the ignition command as the comparison value for judging whether there is a flame, so that the comparison value is a comparison value that changes with the environment. Compared with the prior art, the limit value for judging whether there is a flame is a fixed value, and the situation that the burner itself has no flame but the main control board detects a flame signal will not occur.

[0062] In some embodiments of the present application, as shown in Fig. 2 In step S5, it is judged whether the difference value △I is greater than the first current set value Iset1, if yes, it is judged whether the duration that the difference value △I is greater than the first current set value Iset1 is greater than the fifth set time Tset5, if yes, the flame detection circuit is controlled to output a signal indicating that there is a flame; it is judged whether the difference value △I is less than the second current set value Iset2, if yes, it is judged whether the duration that the difference value △I is less than the second current set value Iset2 is greater than the sixth set time Tset6, if yes, the flame detection circuit is controlled to output a signal indicating that there is no flame.

[0063] In step S6, it is judged whether the difference value △I is greater than the third current set value Iset3, if yes, it is judged whether the duration that the difference value △I is greater than the third current set value Iset3 is greater than the seventh set time Tset7, if yes, the flame detection circuit is controlled to output a signal indicating that there is a flame; it is judged whether the difference value △I is less than the fourth current set value Iset4, if yes, it is judged whether the duration that the difference value △I is less than the fourth current set value Iset4 is greater than the eighth set time Tset8, if yes, the flame detection circuit is controlled to output a signal indicating that there is no flame.

[0064] In the preferred scheme, Tset5 is 0.5s-0.8s; Tset6 is 0.5s-0.8s; Tset7 is 0.5s-0.8s, and Tset8 is 0.5s-0.8s; I 回差1Take 0.2-0.4; I 回差2 Take 0.2-0.4.

[0065] In the above scheme, when judging whether there is flame, a duration judgment condition is added, which can avoid the frequent output of control signals caused by the fluctuation of flame current value due to unstable flame.

[0066] For example, Tset1 is 30s, Iset1 is 0.3uA, Iset2 is 0.1uA, Iset3 is 0.8uA, Iset4 is 0.5uA, Tset5 is 0.5s, and Tset6 is 0.8s.

[0067] Then, when the ignition is less than 30s, if the difference value AI is greater than 0.3uA and lasts more than 0.5s, it is judged that there is flame, and if the difference value AI is less than 0.1uA and lasts more than 0.8s, it is judged that there is no flame; when the ignition is greater than or equal to 30s, if the difference value AI is greater than 0.8uA and lasts more than 0.5s, it is judged that there is flame, and if the difference value AI is less than 0.5uA and lasts more than 0.8s, it is judged that there is no flame.

[0068] It should be noted that the above parameters can be different for different models of gas water heaters, and can also be different for different environments of the gas water heater.

[0069] When the flame detection circuit outputs a signal indicating that there is flame, it means that the ignition has been successful, at this time, the main control board will adjust the opening of the gas valve according to the water flow signal of the water flow sensor to adjust the size of the flame, so that the gas water heater operates with the actual heat demand of the user.

[0070] When the flame detection circuit outputs a signal indicating that there is no flame, the main control board will control the igniter to discharge and ignite again. At this time, it is necessary to judge whether the number of times of discharging and igniting the igniter again exceeds a predetermined number of times, if so, the alarm will send an alarm signal.

[0071] In the above scheme, the inductive needle is heated by multiple ignitions, which can improve the success rate of ignition. However, the number of repeated ignitions is also limited, and if the flame cannot be detected after repeated ignition for many times, a fault is reported, and the user can notify the maintenance personnel to repair the water heater, avoiding the safety hazards caused by using a water heater with a fault.

[0072] In some embodiments of the present application, as Fig. 3As shown, between step S1 and step S2, there is also step A1: controlling the fan to start, entering the pre-cleaning process, and obtaining the flame current value I0 in the flame detection circuit, judging whether the flame current value I0 at the current time is greater than the seventh current setting value Iset7, if yes, judging whether the duration that the flame current value I0 at the current time is greater than the seventh current setting value Iset7 is greater than the fourth setting time Tset4, if yes, executing step S2, if no, controlling the alarm to send an alarm signal.

[0073] The function of step A1 in the above scheme is to detect the fault of the flame detection circuit. Generally, after the water flow sensor of the water heater senses the change of water flow, it sends the command of ignition to the main control board. In order to ignite successfully in time and to have good combustion after ignition, the main control board should control the fan to start and perform the pre-cleaning process before controlling the igniter to discharge. Then, the flame detection circuit can be detected during the pre-cleaning process to judge whether it has a fault. If the flame detection circuit has a fault, the fault alarm is reported. If the flame detection circuit has no fault, the subsequent process can be performed.

[0074] The above only describes the preferred embodiments of the present application and is not intended to limit the present application in any form. Although the present application has been disclosed as above with the preferred embodiments, it is not intended to limit the present application. Any skilled person in the art of the present patent can make some changes or modifications to the above-mentioned technical content without departing from the technical solution of the present application to obtain equivalent embodiments with equivalent changes. Any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present application, as long as it does not depart from the technical solution of the present application, still belongs to the scope of the present application.

Claims

1. A method of controlling a gas water heater, the method comprising: The method comprises the following steps: S1, obtaining an ignition command; S2, detecting and storing an initial value I0 of a flame current in a flame detection circuit at a current time; S3, controlling the ignition of the igniter and the opening of the gas valve, detecting a real-time flame current value I1, and obtaining a difference value ΔI=I1-I0; S4, obtaining a time difference value ΔT between the time at which the real-time flame current value I1 in the flame detection circuit is detected and the time at which the igniter is controlled to ignite, and determining whether the time difference value ΔT is less than a first set time Tset1, if yes, executing step S5, and if no, executing step S6; S5, determining whether the difference value ΔI is greater than a first current set value Iset1, if yes, controlling the flame detection circuit to output a signal indicating that there is a flame, and determining whether the difference value ΔI is less than a second current set value Iset2, if yes, controlling the flame detection circuit to output a signal indicating that there is no flame; S6, determining whether the difference value ΔI is greater than a third current set value Iset3, if yes, controlling the flame detection circuit to output a signal indicating that there is a flame, and determining whether the difference value ΔI is less than a fourth current set value Iset4, if yes, controlling the flame detection circuit to output a signal indicating that there is no flame; where Iset1 = Iset2 + I 回差1 , Iset3 = Iset4 + I 回差2 ; Iset3 is greater than Iset1; and Iset4 is greater than Iset2. In step S4, the following is further included: determining whether the time difference value ΔT is less than a second set time Tset2, if yes, determining whether the flame current value I1 in the flame detection circuit is less than a fifth current set value Iset5, if yes, controlling the burner to operate at an ignition power; wherein Tset2=(1 / 3~1 / 2)Tset1.

2. The method according to claim 1, wherein: In steps S5 and S6, the following is further included: after controlling the flame detection circuit to output a signal indicating that there is a flame, determining whether the flame current value I1 in the flame detection circuit is greater than a sixth current set value Iset6, if yes, determining whether a duration for which the flame current value I1 in the flame detection circuit is greater than the sixth current set value Iset6 is greater than a third set time Tset3, if yes, controlling the burner and the gas valve to be closed.

3. The method according to claim 1, wherein: In steps S5 and S6, the following is further included: after controlling the flame detection circuit to output a signal indicating that there is no flame, controlling the igniter to ignite again.

4. The method according to claim 3, wherein: In steps S5 and S6, the following is further included: determining whether the number of times that the igniter ignites again exceeds a predetermined number of times, if yes, controlling an alarm to output an alarm signal.

5. The method according to claim 1, wherein: between steps S1 and S2, step A1 is further included: Controlling the fan to start, entering the pre-cleaning process, and obtaining the flame current value I0 in the flame detection circuit, determining whether the flame current value I0 at the current time is greater than the seventh current setting value Iset7, if yes, determining whether the duration of the flame current value I0 at the current time being greater than the seventh current setting value Iset7 is greater than the fourth setting time Tset4, if yes, executing step S2, if no, controlling the alarm to send an alarm signal.

6. The gas water heater control method of any one of claims 1-5, characterized in that: In step S5, determining whether the difference value AI is greater than the first current setting value Iset1, if yes, determining whether the duration of the difference value AI being greater than the first current setting value Iset1 is greater than the fifth setting time Tset5, if yes, controlling the flame detection circuit to output a signal indicating that there is flame; determining whether the difference value AI is less than the second current setting value Iset2, if yes, determining whether the duration of the difference value AI being less than the second current setting value Iset2 is greater than the sixth setting time Tset6, if yes, controlling the flame detection circuit to output a signal indicating that there is no flame.

7. The gas water heater control method of claim 6, characterized in that: Tset5 is taken as 0.5s-0.8s, and Tset6 is taken as 0.5s-0.8s.

8. The gas water heater control method of any one of claims 1-5, characterized in that: In step S6, determining whether the difference value AI is greater than the third current setting value Iset3, if yes, determining whether the duration of the difference value AI being greater than the third current setting value Iset3 is greater than the seventh setting time Tset7, if yes, controlling the flame detection circuit to output a signal indicating that there is flame; determining whether the difference value AI is less than the fourth current setting value Iset4, if yes, determining whether the duration of the difference value AI being less than the fourth current setting value Iset4 is greater than the eighth setting time Tset8, if yes, controlling the flame detection circuit to output a signal indicating that there is no flame.

9. The gas water heater control method of claim 8, characterized in that: Tset7 is taken as 0.5s-0.8s, and Tset8 is taken as 0.5s-0.8s.

10. The gas water heater control method of any one of claims 1-5, characterized in that: I 回差1 Take 0.2~0.4;I 回差2 Take 0.2~0.

4.

11. A gas water heater characterized by: The control method of any one of claims 1-10 is adopted.

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