Gas water heater and control method thereof

Abstract

The present application relates to a gas water heater and a control method thereof. The gas water heater comprises a heat exchanger, a cold water pipe, a hot water pipe, a water inlet pipe, a water outlet pipe and an automatic constant temperature device. The automatic constant temperature device comprises a tank body and an elastic diaphragm, the elastic diaphragm divides a space in the tank body into a fluid-isolated first sub-space and a second sub-space, a first communication port and a second communication port are both in communication with the first sub-space, and a third communication port and a fourth communication port are both in communication with the second sub-space. The elastic diaphragm is configured to generate elastic deformation protruding towards the second sub-space under the action of water inlet pressure when water use is started at a water use end, and to restore the deformation under the action of its own elastic deformation restoring force when water use is stopped at the water use end. Thus, hot water flowing out of the hot water pipe first flows to the second sub-space to mix with water stored in the second sub-space and then flows to the water outlet pipe, the mixing space is larger, the mixing speed is faster, and the water mixing effect is better.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of water heaters, in particular to a gas water heater and a control method thereof. BACKGROUND

[0002] Currently, when the water valve of a gas water heater on the market is closed and then opened again, a process of high-temperature hot water-cold water-normal temperature hot water needs to be experienced, which is referred to as a sandwich phenomenon. That is, the water heater needs to be stable to the set bathing temperature after a period of time after restarting, which seriously affects the bathing comfort of the user. The main reason for the above problem is that after the water valve is closed, the heat exchanger continues to heat the stored water in the machine, so that the temperature of the stored water is higher than the set temperature, and when the water valve is opened again, the high-temperature stored water will flow out first to form high-temperature hot water; the water heater uses a water flow signal as a starting signal, so when the water valve is opened again to generate a water flow, the water heater will start to work by ignition, and a period of time is needed from when the water flow signal is received by the water heater to when the water temperature of the water heater reaches the set value, and during this period of time, the flowing water is not heated and flows out from the water valve to form a certain amount of cold water section.

[0003] The following methods are usually used in the prior art to solve the above technical problems. First, a water mixing device is added; some gas water heaters currently add a water mixing tank at the outlet pipe, and when the user uses hot water, part of the hot water will be stored in the water mixing tank, and when the water valve is closed and then restarted, the sandwich water in the outlet pipe will be mixed with the hot water in the tank and then flow out. Second, an electric heating module is added, which heats the cold water flowing through the electric heating module to eliminate the cold water in the sandwich water when the water valve is closed and then restarted. Third, energy storage materials are used, which absorb heat when the water is normally used, and release the stored heat to heat the cold water flowing through when the water valve is closed and then restarted.

[0004] However, the electric heating module has high development cost and complex control program, and the electric heating module will be covered with scale formed by ions in the water, which will greatly reduce the heating efficiency as the use time increases. Energy storage materials are expensive and not mature in technology, and the performance of the materials does not meet the use requirements, which are only in the theoretical stage and have not been put into actual use. Therefore, the most cost-effective and simplest solution is the water mixing tank solution, but the existing water mixing tank solution only connects a large water tank at the end of the outlet pipe, which is not reasonably designed, resulting in limited hot water flow from the water mixing tank and poor water mixing effect, which cannot effectively solve the cold water problem. SUMMARY

[0005] One object of the first aspect of the present application aims to overcome at least one defect of the prior art and provide a gas water heater with faster mixing speed and better water mixing effect.

[0006] The second aspect of the present application is to provide a control method of a gas water heater capable of avoiding frequent starting of an ignition system.

[0007] According to the first aspect of the present application, the present application provides a gas water heater, comprising a heat exchanger, a cold water pipe connected on an upstream side of the heat exchanger, a hot water pipe connected on a downstream side of the heat exchanger, a water inlet pipe for connecting with a tap water pipe, a water outlet pipe for connecting with a water using end, and an automatic constant temperature device, the automatic constant temperature device comprising:

[0008] a tank body having a first communication port, a second communication port, a third communication port and a fourth communication port in communication with the water inlet pipe, the cold water pipe, the hot water pipe and the water outlet pipe respectively; and

[0009] an elastic diaphragm arranged in the tank body and dividing a space in the tank body into a first sub-space and a second sub-space in fluid isolation, the first communication port and the second communication port being in communication with the first sub-space, and the third communication port and the fourth communication port being in communication with the second sub-space; and

[0010] the elastic diaphragm is configured to generate an elastic deformation protruding towards the second sub-space under the action of the water inlet pressure when the water using end starts water using, and to restore the deformation under the action of its own elastic deformation restoring force when the water using end stops water using.

[0011] Optionally, the elastic diaphragm is in a natural state when the water using end continuously stops water using; and

[0012] the elastic deformation restoring force generated by the elastic diaphragm is the same as the water inlet pressure acting on the elastic diaphragm when the water using end continuously uses water, and the elastic diaphragm remains in a deformed state protruding towards the second sub-space.

[0013] Optionally, the gas water heater further comprises:

[0014] a flow sensor for detecting a water flow in the cold water pipe; and

[0015] an ignition system configured to be controlled to start ignition when the water flow in the cold water pipe reaches a preset ignition flow.

[0016] Optionally, the automatic constant temperature device further comprises a limiting plate arranged in the second sub-space, the limiting plate being configured to prevent the elastic diaphragm from continuously deforming protruding towards the second sub-space after the elastic diaphragm deforms protruding towards the second sub-space to a preset extent.

[0017] Optionally, the automatic constant temperature device further comprises a thermal insulation layer wrapped on an outer portion of the tank body.

[0018] According to a second aspect of the present application, the present application further provides a control method of the gas water heater according to any one of the above-mentioned solutions, the gas water heater further comprising a solenoid valve arranged in the cold water pipe to adjust the flow area of the cold water pipe, and a temperature sensor for obtaining the water temperature in the second sub-space, the control method comprising:

[0019] receiving a water use start signal, the water use start signal being indicative of the water use end starting water use;

[0020] obtaining the water temperature in the second sub-space;

[0021] calculating a temperature difference between the set temperature of the gas water heater and the water temperature; and

[0022] setting an initial opening degree of the solenoid valve according to the temperature difference.

[0023] Optionally, the step of setting the initial opening degree of the solenoid valve according to the temperature difference comprises:

[0024] if the temperature difference is greater than a preset temperature difference value, setting the initial opening degree of the solenoid valve to a preset maximum opening degree;

[0025] if the temperature difference value is less than or equal to the preset temperature difference value, setting the initial opening degree of the solenoid valve to zero.

[0026] Optionally, after setting the initial opening degree of the solenoid valve to zero, the control method further comprises:

[0027] obtaining a total amount of water flowing out of the water outlet pipe since receiving the water use start signal;

[0028] when the total amount of water reaches a preset water amount, setting the opening degree of the solenoid valve to a preset ignition opening degree to prompt the ignition system of the gas water heater to start; wherein

[0029] the preset ignition opening degree is set such that the water flow in the cold water pipe is exactly equal to a preset ignition flow that prompts the ignition system to start.

[0030] Optionally, after setting the opening degree of the solenoid valve to the preset ignition opening degree, the control method further comprises:

[0031] receiving an ignition start signal, the ignition start signal being generated when the water flow in the cold water pipe reaches the preset ignition flow;

[0032] starting the ignition system;

[0033] obtaining the water flow in the water outlet pipe; and

[0034] The opening degree of the electromagnetic valve is adjusted according to the water flow in the outlet pipe until the opening degree of the electromagnetic valve reaches the preset maximum opening degree.

[0035] Optionally, the step of adjusting the opening degree of the electromagnetic valve according to the water flow in the outlet pipe comprises:

[0036] The opening degree of the electromagnetic valve is calculated according to the following formula:

[0037] y t =kxt+y0; wherein

[0038] y t represents the opening degree of the electromagnetic valve at the time t since the ignition start signal is received, t represents the water use time since the ignition start signal is received, y0 represents the preset minimum opening degree, and k represents a coefficient proportional to the user water use amount.

[0039] Optionally, after the opening degree of the electromagnetic valve reaches the preset maximum opening degree, the control method further comprises:

[0040] receiving a water use stop signal, the water use stop signal being used to indicate that the water use end stops water use; and

[0041] adjusting the opening degree of the electromagnetic valve to a preset standby opening degree; wherein

[0042] The preset standby opening degree is greater than zero and less than the preset minimum opening degree.

[0043] The gas water heater of the present application divides the traditional cold water inlet pipe and hot water outlet pipe into two sections respectively, forms four parts of cold water pipe, hot water pipe, water inlet pipe and water outlet pipe, and particularly sets an automatic constant temperature device with a tank and an elastic diaphragm. The elastic diaphragm divides the space in the tank into a fluid-isolated first subspace and a second subspace. The water inlet pipe and the cold water pipe are communicated with the first subspace through a first communication port and a second communication port on the tank respectively, and the hot water pipe and the water outlet pipe are communicated with the second subspace through a third communication port and a fourth communication port on the tank respectively. Thus, the hot water flowing out of the hot water pipe first flows to the second subspace and mixes with the water stored in the second subspace, and then flows to the water outlet pipe. Compared with the prior art, the mixing space of the present application is larger, so the mixing speed is faster and the water mixing effect is better.

[0044] Further, when receiving the water starting signal, first, the water temperature in the second sub-space is acquired, the initial opening of the electromagnetic valve is set according to the temperature difference between the set temperature of the gas water heater and the water temperature in the second sub-space, the initial water flow in the cold water pipe is controlled by controlling the initial opening of the electromagnetic valve, and the speed of the elastic diaphragm deformation is indirectly controlled, that is, the proportion of the stored water in the second sub-space in the water flowing out of the water outlet pipe is controlled. In this way, when the water temperature in the second sub-space is close to the set temperature, more stored water in the second sub-space can be preferentially output, and when the water temperature in the second sub-space is greatly different from the set temperature, more hot water after heat exchange of the heat exchanger is supplemented into the second sub-space to mix with the stored water in the second sub-space and then flows out through the water outlet pipe. It can be understood that if the water consumption at the water consumption end is small, the stored water in the second sub-space can meet the user's demand, and at this time, the ignition system does not need to be started at all. The present application avoids the frequent starting of the ignition system as much as possible under the premise of meeting the user's requirement for water temperature, reduces the noise caused by the frequent starting of the ignition system, avoids the fatigue failure of parts, thereby prolonging the service life and reducing the probability of safety accidents.

[0045] The above and other objects, advantages and features of the present application will become more apparent from the following detailed description of some embodiments thereof, when taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0046] Some embodiments of the present application will now be described in detail in connection with the accompanying drawings, in which the same reference numerals are used to identify the same components in the various figures. It should be understood that the drawings are not necessarily to scale as the emphasis as should be placed upon the illustrative aspects of the application. In the drawings:

[0047] Figure 1 is a schematic structural view of a gas water heater in a stop water state according to an embodiment of the present application;

[0048] Figure 2 is a schematic structural view of a gas water heater in a continuous water state according to an embodiment of the present application;

[0049] Figure 3 is a schematic flow chart of a control method of a gas water heater according to an embodiment of the present application;

[0050] Figure 4 is a schematic flow chart of a control method of a gas water heater according to another embodiment of the present application;

[0051] Figure 5 is a schematic flow chart of a control method of a gas water heater according to still another embodiment of the present application;

[0052] Figure 6is a schematic flow chart of a control method of a gas water heater according to another embodiment of the present application. DETAILED DESCRIPTION

[0053] The present application provides a gas water heater, Figure 1 is a schematic structural diagram of a gas water heater according to an embodiment of the present application in a stop water output state, Figure 2 is a schematic structural diagram of a gas water heater according to an embodiment of the present application in a continuous water output state. Referring to Figures 1 to 2 The gas water heater 1 of the present application comprises a heat exchanger 10, a cold water pipe 21 connected to an upstream side of the heat exchanger 10, a hot water pipe 22 connected to a downstream side of the heat exchanger 10, a water inlet pipe 23 for connecting to a tap water pipe, a water outlet pipe 24 for connecting to a water using end, and an automatic constant temperature device 30. It can be understood that the water using end can be a faucet, a bathing shower, etc.

[0054] In particular, the automatic constant temperature device 30 comprises a tank body 31 and an elastic diaphragm 32. The tank body 31 has a first communication port 311, a second communication port 312, a third communication port 313 and a fourth communication port 314 which are in communication with the water inlet pipe 23, the cold water pipe 21, the hot water pipe 22 and the water outlet pipe 24 respectively. The elastic diaphragm 32 is arranged in the tank body 31 and divides a space in the tank body 31 into a first sub-space 315 and a second sub-space 316 which are fluidly isolated, the first communication port 311 and the second communication port 312 are in communication with the first sub-space 315, and the third communication port 313 and the fourth communication port 314 are in communication with the second sub-space 316. The elastic diaphragm 32 is configured to generate an elastic deformation protruding towards the second sub-space 316 under the action of the water inlet pressure when the water using end starts water using, and to recover the deformation under the action of its own elastic deformation recovery force when the water using end stops water using.

[0055] The gas water heater 1 of the present application divides the conventional cold water inlet pipe and hot water outlet pipe into two sections respectively, forms four parts of the cold water pipe 21, the hot water pipe 22, the water inlet pipe 23 and the water outlet pipe 24, and particularly provides the automatic constant temperature device 30 with the tank body 31 and the elastic diaphragm 32. The elastic diaphragm 32 divides the space in the tank body 31 into the first sub-space 315 and the second sub-space 316 which are fluidly isolated, the water inlet pipe 23 and the cold water pipe 21 are in communication with the first sub-space 315 through the first communication port 311 and the second communication port 312 on the tank body 31 respectively, and the hot water pipe 23 and the water outlet pipe 24 are in communication with the second sub-space 316 through the third communication port 313 and the fourth communication port 134 on the tank body 31 respectively. Thus, the hot water flowing out of the hot water pipe 23 first flows to the second sub-space 316, mixes with the water stored in the second sub-space 316 and then flows to the water outlet pipe 24, compared with the prior art which mixes in the hot water outlet pipe, the mixing space of the present application is larger, therefore, the mixing speed is faster and the water mixing effect is better.

[0056] In some embodiments, when the water-using end continuously stops using water, the elastic diaphragm 32 is in a natural state. When the water-using end continuously uses water, the elastic diaphragm 32 generates an elastic deformation restoring force equal to the water inlet pressure acting on the elastic diaphragm 32, and the elastic diaphragm 32 remains in a deformed state protruding toward the second sub-space 316.

[0057] In some embodiments, the gas water heater 1 further comprises a flow sensor 41 and an ignition system. The flow sensor 41 is configured to detect the water flow in the cold water pipe 21, and the ignition system is configured to controllably start ignition when the water flow in the cold water pipe 21 reaches a preset flow threshold.

[0058] Specifically, the flow sensor 41 can be arranged in the cold water pipe 21 to directly obtain the water flow in the cold water pipe 21. The ignition system can specifically include a gas proportional valve, a gas delivery pipeline, an igniter, etc. Since the ignition system is a common structure of the gas water heater 1, it will not be described here.

[0059] The working process of the gas water heater will be described in detail below.

[0060] When the water-using end continuously stops using water, the water inlet pressure at the water inlet pipe 23 is the same as the water outlet pressure at the water outlet pipe 24, and the elastic diaphragm 32 is in a natural state. At this time, the second sub-space 316 with a larger volume stores hot water flowing from the heat exchanger 10 after the last water use on the water-using end.

[0061] When the water-using end starts using water, the pressure at the water outlet pipe 24 drops sharply, and the water inlet pressure at the water inlet pipe 23 is greater than the water outlet pressure at the water outlet pipe 24. Water flows into the first sub-space 315 through the water inlet pipe 23 and the first communication port 311, presses the elastic diaphragm 32, and causes the elastic diaphragm 32 to elastically deform toward the second sub-space 316. The elastic deformation of the elastic diaphragm 32 presses the hot water in the second sub-space 316 toward the water outlet pipe 24, so that the water-using end can obtain hot water in time. At the same time, part of the water flowing from the water inlet pipe 24 flows to the cold water pipe 21 through the second communication port 312, and when the water flow in the cold water pipe 21 reaches a preset ignition flow, the ignition system starts. The temperature of the water flowing in this period from the time when the ignition system receives the ignition start signal to the time when the heat exchanger 10 heats the water to a set temperature is also neutralized with the pre-stored warm water in the second sub-space 316 and then flows out from the water outlet pipe 24, solving the problem of cold water when the water-using end stops using water for a short time and then uses water again.

[0062] If the water-using end continuously uses water, as the water-using time extends, the elastic diaphragm 32 generates an elastic deformation restoring force equal to the water inlet pressure acting on the elastic diaphragm 32, and the elastic diaphragm 32 no longer deforms.

[0063] When water usage ends or stops, the pressure in the inlet pipe 23 and outlet pipe 24 equalizes again, meaning the water pressure on both sides of the elastic diaphragm 32 is balanced, and the ignition system shuts off. At this time, the elastic diaphragm 32 begins to recover its deformation. Under its own elastic deformation recovery force, the elastic diaphragm 32 begins to contract and recover its deformation towards the first subspace 315. During this process, water in the first subspace 315 is pushed from the cold water pipe 21 into the heat exchanger 10, where it absorbs the residual heat and is stored in the second subspace 316 until the elastic diaphragm 32 returns to its natural state. At this time, the second subspace 316 stores a large amount of warm water at a suitable temperature for the next use by the user. If the time interval between the current water usage and the previous water usage is short, the water entering the cold water pipe 21 will carry away the residual heat of the heat exchanger, forming hot water at a higher temperature. This hot water mixes with the pre-stored warm water in the second subspace 316 to neutralize the temperature before flowing out from the outlet pipe 24, solving the problem of excessively hot water when the user resumes use after a short water outage.

[0064] As can be seen, the present invention, by setting an elastic diaphragm 32 inside the tank 31, uses the inlet water pressure to cause the elastic diaphragm 32 to deform when water is started at the water-using end; and uses the elastic deformation recovery force generated by the elastic diaphragm 32 to cause it to recover its deformation when water is stopped at the water-using end. The structural design is very ingenious, and no additional driving device is required. It achieves the above-mentioned many good technical effects with a very simple structure.

[0065] In some embodiments, the automatic temperature control device 30 further includes a limiting plate 34 disposed within the tank 31. The limiting plate 34 is configured to prevent the elastic diaphragm 32 from continuing to bulge and deform toward the second subspace 316 after the elastic diaphragm 32 has bulged and deformed toward the second subspace 316 to a preset degree. Thus, excessive deformation of the elastic diaphragm 32 that cannot recover its deformation can be avoided when there are large fluctuations in water pressure.

[0066] In some embodiments, the automatic thermostat 30 further includes an insulation layer (not shown in the figure) that covers the outside of the tank 31, thereby preventing heat loss from the water stored in the second subspace 316, so that hot water can still be obtained in a timely manner when the water is turned on again after a long period of inactivity.

[0067] The present invention also provides a control method for a gas water heater, which is designed based on a gas water heater having any of the above embodiments. Furthermore, the gas water heater 1 also includes a solenoid valve 50 disposed within the cold water pipe 21 to adjust the flow area of ​​the cold water pipe 21, and a temperature sensor (not shown) for acquiring the water temperature within the second subspace 316.

[0068] Figure 3is a schematic flow chart of a control method of a gas water heater according to an embodiment of the present application. The control method of the present application comprises:

[0069] In step S10, a water use start signal is received, which is used to indicate that the water use end starts water use.

[0070] In step S20, the water temperature in the second sub-space 316 is obtained.

[0071] In step S30, the temperature difference between the set temperature of the gas water heater 1 and the water temperature in the second sub-space 316 is calculated; and

[0072] In step S40, the initial opening of the electromagnetic valve 50 is set according to the temperature difference.

[0073] The gas water heater 1 of the present application, upon receiving the water use start signal, first obtains the water temperature in the second sub-space 316, sets the initial opening of the electromagnetic valve 50 according to the temperature difference between the set temperature of the gas water heater 1 and the water temperature in the second sub-space 316, controls the initial water flow in the cold water pipe 21 by controlling the initial opening of the electromagnetic valve 50, and indirectly controls the speed of deformation of the elastic diaphragm 32, i.e. controls the proportion of the stored water in the second sub-space 316 in the water flowing out of the water outlet pipe 24. In this way, when the water temperature in the second sub-space 316 is close to the set temperature, more stored water in the second sub-space 316 is preferentially output, and when the water temperature in the second sub-space 316 is greatly different from the set temperature, more hot water after heat exchange in the heat exchanger 10 is supplemented into the second sub-space 316 to mix with the stored water in the second sub-space 316 before flowing out through the water outlet pipe 24. It can be understood that if the water use amount of the water use end is small, the stored water in the second sub-space 316 can meet the user's demand, and at this time the ignition system does not need to be started at all. The present application avoids frequent starting of the ignition system as much as possible under the premise of meeting the user's water temperature requirement, reduces the noise caused by frequent starting of the ignition system, avoids fatigue failure of parts, thereby prolonging the service life and reducing the probability of safety accidents.

[0074] Further, if the water use amount of the water use end is large, the water temperature output by the ignition system needs to be stable at the set temperature after a period of time, and before that, if more stored water in the second sub-space 316 with a temperature close to the set temperature is preferentially output, the user's water waiting time can be reduced, and the user's experience can be improved.

[0075] It should be noted that the ignition system of the present application is a broad sense including a gas valve, which is used to control the ignition and extinguishing of the gas water heater. The starting of the ignition system means controlling the ignition of the gas water heater, and the stopping of the ignition system means controlling the extinguishing of the gas water heater.

[0076] In some embodiments, the step S40 of setting the initial opening degree of the electromagnetic valve 50 according to the temperature difference can specifically include:

[0077] If the temperature difference is greater than the preset temperature difference value, the initial opening degree of the electromagnetic valve 50 is set to a preset maximum opening degree;

[0078] If the temperature difference value is less than or equal to the preset temperature difference value, the initial opening degree of the electromagnetic valve 50 is set to zero.

[0079] Specifically, if the temperature difference is greater than the preset temperature difference value, it means that the water temperature in the second sub-space 316 and the set temperature of the gas water heater 1 differ greatly, and it is difficult to meet the user's water temperature demand by using the stored water in the second sub-space 316 alone. Therefore, at this time, the present application adjusts the opening degree of the electromagnetic valve 50 to the preset maximum opening degree, so that more water flows into the cold water pipe 21 after the water at the water end is started, so that more water flows into the second sub-space 316 after being heated by the heat exchanger 10, so as to improve the mixed water temperature in the second sub-space 316, and to meet the user's water temperature demand as soon as possible.

[0080] Preferably, the preset maximum opening degree can be 100%.

[0081] If the temperature difference is less than or equal to the preset temperature difference value, it means that the water temperature in the second sub-space 316 is close to the set temperature of the gas water heater 1, and the stored water in the second sub-space 316 can basically meet the user's water temperature demand. Therefore, at this time, the present application sets the initial opening degree of the electromagnetic valve 50 to zero, so that the stored water in the second sub-space 316 can be output to the water outlet pipe 24 alone when the water at the water end is started, that is, the stored water in the second sub-space 316 is preferentially output. In this way, when the water consumption at the water end is small, the stored water in the second sub-space 316 can meet the user's demand, and at this time, the flow through the heat exchanger is not needed, avoiding frequent starting of the ignition system, reducing the noise caused by frequent starting of the ignition system, avoiding fatigue failure of parts, thereby prolonging the service life and reducing the probability of safety accidents.

[0082] Specifically, Figure 4 is a schematic flow chart of a control method of a gas water heater according to another embodiment of the present application. The control method of the present application comprises:

[0083] Step S10, receiving a water starting signal, the water starting signal being used to indicate that the water at the water end is started;

[0084] Step S20, obtaining the water temperature in the second sub-space 316;

[0085] Step S30, calculating the temperature difference between the set temperature of the gas water heater 1 and the water temperature in the second sub-space 316;

[0086] Step S41, judging whether the temperature difference is greater than a preset temperature difference value; if yes, turning to step S42, if not, turning to step S43;

[0087] Step S42, adjusting the opening of the electromagnetic valve 50 to a preset maximum opening;

[0088] Step S43, adjusting the opening of the electromagnetic valve 50 to zero.

[0089] Figure 5 is a schematic flow chart of a control method of a gas water heater according to still another embodiment of the present application. In some embodiments, after setting the initial opening of the electromagnetic valve 50 to zero, the control method of the present application further comprises:

[0090] Step S51, obtaining the total amount of water flowing out of the water outlet pipe 24 since receiving the water use start signal;

[0091] Step S52, when the total amount of water reaches a preset water amount, setting the opening of the electromagnetic valve 50 to a preset ignition opening to prompt the ignition system of the gas water heater to start.

[0092] In some embodiments, the preset ignition opening is set such that the water flow in the cold water pipe 21 is exactly the preset ignition flow that prompts the ignition system to start.

[0093] That is, in order to ensure the water supply amount, after a certain amount of water is supplied to the user by using the stored water in the second sub-space 316, the opening of the electromagnetic valve 50 needs to be adjusted to start the ignition system in time, so that more water flows through the heat exchanger 10 and is replenished into the second sub-space 316 in time.

[0094] Figure 6 is a schematic flow chart of a control method of a gas water heater according to still another embodiment of the present application. In some embodiments, after setting the initial opening of the electromagnetic valve 50 to zero, the control method of the present application further comprises:

[0095] Step S61, receiving an ignition start signal, which is generated when the water flow in the cold water pipe 21 reaches a preset ignition flow;

[0096] Step S62, starting the ignition system;

[0097] Step S63, obtaining the water flow in the water outlet pipe 24; and

[0098] Step S64, adjusting the opening of the electromagnetic valve 50 according to the water flow in the water outlet pipe 24 until the opening of the electromagnetic valve 50 reaches a preset maximum opening.

[0099] That is, after the ignition system starts, the opening of the electromagnetic valve is not constant, but a variable related to the water flow in the water outlet pipe 24.

[0100] Specifically, the water flow rate in the water outlet pipe 24 can be measured by the flow sensor 42 arranged in the water outlet pipe 24. The total amount of water flowing out of the water outlet pipe 24 can be obtained by multiplying the water flow rate measured by the flow sensor 42 by the water use time.

[0101] Further, the step of adjusting the opening degree of the electromagnetic valve 50 according to the water flow rate in the water outlet pipe 24 comprises:

[0102] The opening degree of the electromagnetic valve 50 is calculated according to the following formula:

[0103] y t = kxt + y0; where

[0104] y t represents the opening degree of the electromagnetic valve 50 at the time t since the ignition start signal is received, t represents the water use time since the ignition start signal is received, y0 represents the preset minimum opening degree, and k represents a coefficient proportional to the user water flow rate. That is, a plurality of different values of k can be preset, and the greater the user water flow rate (e.g., the greater the faucet opening degree), the greater the value of k.

[0105] According to the above determination of the opening degree of the electromagnetic valve 50, the present application can gradually increase the opening degree of the electromagnetic valve 50 from the preset minimum opening degree after the ignition start signal is received, so as to ensure that sufficient water flows through the heat exchanger 10 to be heated and then supplied to the second sub-space 316, so as to meet the user's water use demand.

[0106] Further, after the opening degree of the electromagnetic valve 50 reaches the preset maximum opening degree, the control method of the present application further comprises:

[0107] Step S71, receiving a water use stop signal, the water use stop signal being used to indicate that the water use end stops water use;

[0108] Step S72, adjusting the opening degree of the electromagnetic valve 50 to a preset standby opening degree; wherein

[0109] The preset standby opening degree is greater than zero and less than the above-mentioned preset minimum opening degree.

[0110] That is, when the water usage at the water usage end is stopped, the fluid is allowed to continue to flow through the cold water pipe 21, but the maximum allowable flow rate in the cold water pipe 21 is less than the preset ignition flow rate. This is because, when the water usage stop signal is received, the pressure in the water inlet pipe 23 and the water outlet pipe 24 is balanced again, that is, the water pressure on both sides of the elastic diaphragm 32 is balanced, at this time, the elastic diaphragm 32 begins to recover the deformation, and pushes the water in the first sub-space 315 in the cold water pipe 21 into the heat exchanger 10, and then into the second sub-space 316 after absorbing the residual heat of the heat exchanger 10 until the elastic diaphragm 32 recovers to the natural state. During this process, by controlling the opening of the electromagnetic valve 50, the water flow rate in the cold water pipe 21 can be prevented from reaching the preset ignition flow rate to cause the ignition system to start again.

[0111] In some embodiments, after receiving the water usage stop signal, the control method of the present application further comprises:

[0112] receiving an ignition stop signal; the ignition stop signal is generated when the water flow rate in the cold water pipe 21 is less than the preset ignition flow rate; and

[0113] stopping the ignition system.

[0114] As described above, when the water usage at the water usage end is stopped, the opening of the electromagnetic valve 50 is greater than zero and less than the preset minimum opening, at this time, the water flow rate in the cold water pipe 21 is necessarily less than the preset ignition flow rate, therefore, the ignition system is stopped to control the flameout when the water usage at the water usage end is stopped. Specifically, the water flow rate in the cold water pipe 21 can be obtained by the flow rate sensor 41 arranged in the cold water pipe 21.

[0115] It should be understood by those skilled in the art that the above-described embodiments are only a part of the embodiments of the present application, not all the embodiments of the present application, and the part of the embodiments are intended to explain the technical principles of the present application, not to limit the protection scope of the present application. Based on the embodiments provided by the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor should still fall within the protection scope of the present application.

[0116] It should be noted that in the description of the present application, the terms "first", "second", "third" are only for descriptive purposes, and cannot be understood or implied as indicating or implying relative importance.

[0117] Further, it needs to be explained that in the description of the present application, each functional module can be a physical module composed of multiple structures, components or electronic elements, or a virtual module composed of multiple programs; each functional module can be a module existing independently from each other, or a module divided from a whole module according to functions. It should be understood by those skilled in the art that, as long as the technical solutions described in the present application can be realized, the constituting manner, the implementation manner and the positional relationship of each functional module can be changed in any way without departing from the technical principles of the present application, and thus should fall within the protection scope of the present application.

[0118] At this point, those skilled in the art should recognize that, although the present application has been shown and described in detail in this paper, many other variants or modifications conforming to the principles of the present application can be directly determined or deduced according to the disclosed content of the present application without departing from the spirit and scope of the present application. Therefore, the scope of the present application should be understood and recognized as covering all these other variants or modifications.

Claims

1. A gas water heater comprising a heat exchanger, a cold water pipe connected at an upstream side of the heat exchanger, a hot water pipe connected at a downstream side of the heat exchanger, a water inlet pipe for connecting with a water supply pipe, a water outlet pipe for connecting with a water using end, and an automatic constant temperature device, the automatic constant temperature device comprising: a tank body having a first communication port, a second communication port, a third communication port and a fourth communication port for communicating with the water inlet pipe, the cold water pipe, the hot water pipe and the water outlet pipe respectively; and a resilient diaphragm arranged in the tank body and dividing a space in the tank body into a first sub-space and a second sub-space in fluid isolation, the first communication port and the second communication port both communicating with the first sub-space, and the third communication port and the fourth communication port both communicating with the second sub-space; and the resilient diaphragm is configured to generate a resilient deformation bulging towards the second sub-space under a water inlet pressure when the water using end starts water using, and to restore the resilient deformation under a resilient deformation restoring force of the resilient diaphragm when the water using end stops water using; the gas water heater further comprises a solenoid valve arranged in the cold water pipe for adjusting an over-flow area of the cold water pipe, and a temperature sensor for acquiring a water temperature in the second sub-space, and a control method of the gas water heater comprising: receiving a water using start signal for indicating that the water using end starts water using; acquiring the water temperature in the second sub-space; calculating a temperature difference between a set temperature of the gas water heater and the water temperature; and setting an initial opening degree of the solenoid valve according to the temperature difference.

2. The gas water heater according to claim 1, wherein: the resilient diaphragm is in a natural state when the water using end continuously stops water using; and the resilient deformation restoring force of the resilient diaphragm is the same as the water inlet pressure on the resilient diaphragm when the water using end continuously uses water, and the resilient diaphragm keeps a bulging deformation state towards the second sub-space. further comprising:

3. The gas water heater of claim 1, wherein, a flow sensor for detecting a water flow in the cold water pipe; and an ignition system configured to controllably start ignition when the water flow in the cold water pipe reaches a preset ignition flow.

4. The gas water heater according to claim 1, wherein: the automatic constant temperature device further comprises a limiting plate arranged in the second sub-space, the limiting plate being configured to stop the resilient diaphragm from continuously bulging towards the second sub-space after the resilient diaphragm bulges towards the second sub-space to a preset extent.

5. The gas water heater according to claim 1, wherein: the automatic constant temperature device further comprises a heat preservation layer wrapped outside the tank body. The step of setting the initial opening degree of the solenoid valve according to the temperature difference comprises: if the temperature difference is greater than a preset temperature difference value, setting the initial opening degree of the solenoid valve to a preset maximum opening degree; and 6. A control method for the gas water heater according to any one of claims 1 to 5, wherein if the temperature difference value is less than or equal to the preset temperature difference value, setting the initial opening degree of the solenoid valve to zero.

7. The control method of the gas water heater according to claim 6, wherein after setting the initial opening degree of the solenoid valve to zero, the control method further comprises: ​ ​ an amount of water flowing out of the outlet pipe after the water start signal is received; when the total amount of water reaches a preset water amount, setting the opening of the electromagnetic valve to a preset ignition opening to cause the ignition system of the gas water heater to start; wherein the preset ignition opening is set such that the water flow in the cold water pipe just reaches a preset ignition flow that causes the ignition system to start.

8. The control method of the gas water heater according to claim 7, wherein after the opening of the electromagnetic valve is set to the preset ignition opening, the control method further comprises: receiving an ignition start signal, the ignition start signal being generated when the water flow in the cold water pipe reaches the preset ignition flow; starting the ignition system; acquiring the water flow in the outlet pipe; and adjusting the opening of the electromagnetic valve according to the water flow in the outlet pipe until the opening of the electromagnetic valve reaches the preset maximum opening.

9. The control method of the gas water heater according to claim 8, wherein the step of adjusting the opening of the electromagnetic valve according to the water flow in the outlet pipe comprises: calculating the opening of the electromagnetic valve according to the following formula: y t = k x t + y0; wherein y t represents the opening degree of the electromagnetic valve at time t from when the ignition start signal is received, t represents the elapsed time from when the ignition start signal is received, y0 represents a preset minimum opening degree, and k represents a coefficient that is proportional to the user water amount.

10. The control method of the gas water heater according to claim 8, wherein after the opening of the electromagnetic valve reaches the preset maximum opening, the control method further comprises: receiving a water stop signal, the water stop signal being used to indicate that the water end stops water use; and adjusting the opening of the electromagnetic valve to a preset standby opening; wherein the preset standby opening is greater than zero and less than a preset minimum opening.

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