Control method of gas water heater

Abstract

The application relates to a control method of a gas water heater. The method comprises the following steps: acquiring the outlet water temperature of a heat exchanger when the gas water heater is in a stable working state; acquiring the heat exchange water flow lag time if the fluctuation value of the outlet water temperature of the heat exchanger is greater than a first preset temperature; wherein the heat exchange water flow lag time is the time for water flow to flow from a water tank temperature sensor to a mixing point; and controlling the adjustment time of the bypass ratio of a water proportional valve according to the heat exchange water flow lag time. Through the acquisition of the heat exchange water flow lag time and the flexible control of the adjustment time of the bypass ratio of the water proportional valve according to the heat exchange water flow lag time, the water flow has already flowed to the mixing point when the water proportional valve completes the adjustment, so that the water temperature fluctuation is reduced, and the thermostatic control effect is improved.

Description

Technical Field

[0001] This application relates to the field of gas water heater control technology, and in particular to a control method for a gas water heater. Background Technology

[0002] In existing technology, the bypass mixing thermostatic regulation of gas water heaters mixes hot water heated by the heat exchanger with cold water in the bypass pipe, and then outputs hot water at the target temperature. Since the water proportional valve adjustment is faster than the heating system changing the heating power for thermostatic regulation, the bypass mixing thermostatic regulation can better solve the water temperature fluctuation caused by changes in load demand.

[0003] However, adjusting the bypass ratio will cause changes in water pressure, and the transmission speed of water pressure is faster than the flow speed of water. Therefore, the temperature of the hot and cold water involved in the mixing may be the same as the temperature before the change, which will cause fluctuations in the outlet water temperature. Summary of the Invention

[0004] Therefore, it is necessary to provide a control method for gas water heaters that can reduce fluctuations in actual outlet water temperature, addressing the aforementioned technical problems.

[0005] This application provides a control method for a gas water heater, the gas water heater comprising: a heat exchanger, a water proportioning valve, a cold water pipe, a hot water pipe, and a bypass pipe, wherein the connection between the cold water pipe and the bypass pipe is a water distribution point, the connection between the hot water pipe and the bypass pipe is a water mixing point, and the hot water pipe is equipped with a water tank temperature sensor located between the heat exchanger and the water mixing point.

[0006] The method includes: when the gas water heater is in a stable working state, obtaining the outlet water temperature of the heat exchanger; if the fluctuation value of the outlet water temperature of the heat exchanger is greater than a first preset temperature, obtaining the hot water flow lag time; wherein, the hot water flow lag time is the time it takes for water to flow from the water tank temperature sensor to the mixing point; and controlling the adjustment time of the bypass ratio of the water proportional valve according to the hot water flow lag time.

[0007] In one embodiment, the step of controlling the adjustment time of the bypass ratio of the water proportional valve based on the lag time of the hot water exchange flow includes: obtaining a first control lag time of the water proportional valve; if the lag time of the hot water exchange flow is greater than the first control lag time, adjusting the bypass ratio of the water proportional valve after a first compensation time; wherein, the first compensation time is the difference between the lag time of the hot water exchange flow and the first control lag time.

[0008] In one embodiment, the method further includes: if the hot water flow lag time is less than or equal to the first control lag time, then immediately adjust the bypass ratio of the water proportional valve.

[0009] In one embodiment, the step of obtaining the heat exchanger flow lag time includes: obtaining the current total water flow rate, the current bypass ratio, and the first pipe volume; wherein, the first pipe volume is the pipe volume from the water tank temperature sensor to the mixing point; calculating the heat exchanger water flow rate based on the current total water flow rate and the current bypass ratio; and calculating the heat exchanger flow lag time based on the heat exchanger water flow rate and the first pipe volume.

[0010] In one embodiment, the gas water heater further includes an inlet water temperature sensor, which is located on the bypass pipe, at a water distribution point, or between the inlet and distribution point of the cold water pipe. The method further includes: acquiring the inlet water temperature of the water heater when the gas water heater is in a stable operating state; if the fluctuation value of the inlet water temperature of the water heater is greater than a second preset temperature, acquiring the mixing water flow lag time; wherein, the mixing water flow lag time is the time it takes for water to flow from the inlet water temperature sensor through the bypass pipe to the mixing point; and controlling the adjustment time of the bypass ratio of the water proportional valve according to the mixing water flow lag time.

[0011] In one embodiment, the step of adjusting the bypass ratio of the water proportional valve according to the mixed water flow lag time includes: obtaining a second control lag time of the water proportional valve; if the mixed water flow lag time is greater than the second control lag time, adjusting the bypass ratio of the water proportional valve after a second compensation time; wherein the second compensation time is the difference between the mixed water flow lag time and the second control lag time.

[0012] In one embodiment, the method further includes: if the lag time of the mixed water flow is less than or equal to the second control lag time, then immediately adjusting the bypass ratio of the water proportional valve.

[0013] In one embodiment, when the inlet water temperature sensor is located on the bypass pipe or at the water distribution point, the step of obtaining the lag time of the mixed water flow includes:

[0014] Obtain the current total water flow rate, the current bypass ratio, and the volume of the second pipe; wherein, the volume of the second pipe is the pipe volume from the inlet water temperature sensor to the mixing point; calculate the bypass pipe water flow rate based on the current total water flow rate and the current bypass ratio; calculate the hot water exchange flow lag time based on the bypass pipe water flow rate and the volume of the second pipe.

[0015] In one embodiment, when the inlet water temperature sensor is located between the inlet and the water distribution point, the step of obtaining the mixed water flow lag time includes: obtaining the current total water flow rate, the current bypass ratio, the volume of the third pipe, and the volume of the bypass pipe; wherein, the volume of the third pipe is the pipe volume from the inlet water temperature sensor to the water distribution point; calculating a first time based on the current total water flow rate and the volume of the third pipe; calculating the bypass pipe water flow rate based on the current total water flow rate and the current bypass ratio; calculating a second time based on the bypass pipe water flow rate and the bypass pipe volume; and calculating the mixed water flow lag time based on the first time and the second time.

[0016] In one embodiment, the gas water heater further includes an inlet water temperature sensor, which is disposed on the cold water pipe and located between the water distribution point and the heat exchanger. The method further includes, when the gas water heater is in a stable operating state, acquiring the inlet water temperature of the water heater; if the fluctuation range of the inlet water temperature of the water heater is greater than a second preset temperature, calculating the mixing water flow lag time; wherein, the mixing water flow lag time is the difference between a third time and a fourth time, the third time being the time for water to flow from the water distribution point through the bypass pipe to the mixing point, and the fourth time being the time for water to flow from the water distribution point to the inlet water temperature sensor, the third time being greater than the fourth time; if the mixing water flow lag time is greater than a second control lag time, adjusting the bypass ratio of the water proportional valve after a second compensation time; wherein, the second compensation time is the difference between the mixing water flow lag time and the second control lag time.

[0017] The aforementioned control method for gas water heaters involves acquiring the heat exchanger outlet water temperature under stable operating conditions, calculating the hot water flow lag time when the heat exchanger outlet water temperature fluctuates beyond a first preset temperature, and then controlling the adjustment time of the bypass ratio of the water proportional valve based on this lag time. Therefore, by acquiring the hot water flow lag time and flexibly controlling the adjustment time of the bypass ratio of the water proportional valve based on this lag time, this application ensures that the water flow has reached the mixing point by the time the water proportional valve completes its adjustment, thereby reducing water temperature fluctuations and improving the thermostatic control effect. Attached Figure Description

[0018] Figure 1 This is an application environment diagram of a control method for a gas water heater in one embodiment.

[0019] Figure 2 This is a flowchart illustrating a control method for a gas water heater in one embodiment;

[0020] Figure 3 This is a schematic diagram of the process for controlling the adjustment time of the water proportional valve in one embodiment;

[0021] Figure 4 This is a flowchart illustrating the calculation of the hot water flow lag time in one embodiment;

[0022] Figure 5 This is a flowchart illustrating the control method for a gas water heater in another embodiment;

[0023] Figure 6 This is a schematic diagram of the process for controlling the adjustment time of the water proportional valve in another embodiment;

[0024] Figure 7 This is a flowchart illustrating the calculation of the lag time of the hot water exchange flow in another embodiment;

[0025] Figure 8 This is a structural block diagram of a gas water heater in one embodiment;

[0026] Figure 9 This is a flowchart illustrating the calculation of the lag time of the mixed water flow in one embodiment;

[0027] Figure 10 This is a structural block diagram of a gas water heater in another embodiment;

[0028] Figure 11 This is a flowchart illustrating the control method for a gas water heater in yet another embodiment;

[0029] Figure 12 This is a structural block diagram of a gas water heater in yet another embodiment;

[0030] Explanation of reference numerals in the attached figures:

[0031] Heat exchanger 101, water proportioning valve 102, cold water pipe 103, hot water pipe 104, bypass pipe 105, water distribution point 106, water mixing point 107, water tank temperature sensor 108, inlet water temperature sensor 109. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0033] The bypass mixing control method provided in this application embodiment can be applied to, for example... Figure 1The gas water heater shown includes: a heat exchanger 101, a water proportioning valve 102, a cold water pipe 103, a hot water pipe 104, and a bypass pipe 105. The connection point between the cold water pipe 103 and the bypass pipe 105 is a water distribution point 106, and the connection point between the hot water pipe 104 and the bypass pipe 105 is a mixing point 107. A water tank temperature sensor 108 is installed on the hot water pipe 104, located between the heat exchanger 101 and the mixing point 107. It can be understood that the gas water heater may also include: a water flow sensor and an inlet water temperature sensor, used to detect the inlet water flow and inlet water temperature respectively. The water proportioning valve 102 is used to control the water flow in the bypass pipe 105 according to the bypass ratio sent by the control system.

[0034] Figure 1 The water proportional valve 102 is configured as a three-way water proportional valve 102, and integrates both a water flow sensor and an inlet water temperature sensor. In some other embodiments, a water proportional valve 102 can also be installed on either the cold water pipe 103 or the bypass pipe 105 to control the water flow in the bypass pipe 105. The inlet water temperature sensor can also be installed at other locations on the cold water pipe 103 to detect the inlet water temperature. The bypass ratio is the ratio of the water flow through the bypass pipe 105 to the total water flow. The control system controls the water flow in the bypass pipe 105 by sending corresponding bypass ratio control commands, thereby adjusting the outlet water temperature.

[0035] As described in the background section, existing gas water heaters, upon detecting a change in the outlet water temperature of heat exchanger 101, immediately adjust the calculated outlet water temperature by adjusting the bypass ratio to achieve constant temperature control. However, due to the rapid adjustment of water flow, the water flow rate changes before the water with the changed outlet water temperature reaches the mixing point 107. At this point, the hot water participating in the mixing is the hot water before the change in outlet water temperature, causing the water temperature at the mixing point 107 to deviate from the target water temperature, resulting in water temperature fluctuations and poor constant temperature control.

[0036] For the reasons mentioned above, this application provides a control method for a gas water heater that can reduce fluctuations in the actual outlet water temperature and improve the constant temperature control effect.

[0037] In one embodiment, such as Figure 2 As shown, a bypass mixing control method is provided, which is applied to... Figure 1 Taking a gas water heater as an example, the explanation includes the following steps:

[0038] Step S210: Under the condition that the gas water heater is in a stable working state, obtain the outlet water temperature of the heat exchanger.

[0039] Specifically, when a gas water heater is in a stable operating state, it has already established a heat exchange balance, and the actual outlet water temperature generally does not change. When the load demand changes (fluctuations in inlet water flow rate, fluctuations in inlet water temperature), the heat exchange balance is broken, and the control system needs to adjust the bypass ratio of the water proportional valve 102 to establish a new heat exchange balance. During the adjustment of the bypass ratio, the outlet water temperature of the heat exchanger will also change. At this time, the outlet water temperature of the heat exchanger 101 is detected in real time by the water tank temperature sensor 108, thereby obtaining the outlet water temperature of the heat exchanger.

[0040] Step S220: If the fluctuation value of the heat exchanger outlet water temperature is greater than the first preset temperature, then obtain the heat exchange water flow lag time.

[0041] Specifically, when the fluctuation value of the heat exchanger outlet water temperature is greater than the first preset temperature (e.g., 1 degree Celsius), it indicates that the outlet water temperature of heat exchanger 101 fluctuates significantly, and the user can sensitively perceive the fluctuation in the actual outlet water temperature. In this case, it is necessary to adjust the bypass ratio of the water proportional valve 102 through subsequent steps. First, calculate the hot water flow lag time, which is the time it takes for the water to flow from the water tank temperature sensor 108 to the mixing point 107. By obtaining the current inlet water flow rate and the volume of the pipe through which the water flows, the time it takes for the water to flow from the water tank temperature sensor 108 to the mixing point 107 can be calculated.

[0042] Step S230: Adjust the bypass ratio of the water proportional valve according to the lag time of the hot water flow.

[0043] Specifically, after obtaining the lag time of the hot water flow, the adjustment time of the bypass ratio of the water proportional valve 102 can be flexibly selected according to the specific duration of the lag time. For example, the water proportional valve 102 can be controlled immediately, or it can be controlled after a certain delay, so that when the water proportional valve 102 completes the bypass ratio adjustment, the water flow has already reached the mixing point 107, thereby reducing water temperature fluctuations and improving the thermostatic control effect.

[0044] In one embodiment, such as Figure 3 As shown, in step S230, the adjustment time of the bypass ratio of the water proportional valve is controlled according to the lag time of the hot water flow, including:

[0045] Step S231: Obtain the first control lag time of the water proportional valve.

[0046] Specifically, the first control lag time is the time from when the control system detects a change in the heat exchanger outlet water temperature through the water tank temperature sensor 108 to when the water proportional valve 102 completes the bypass ratio adjustment. The first control lag time is determined by the signal detection and processing system of the gas water heater and the response time of the water proportional valve 102. It can be obtained through prior experimental detection and stored in the gas water heater's memory for direct retrieval when needed.

[0047] Step S232: If the hot water flow delay time is greater than the first control delay time, the bypass ratio of the water proportional valve is adjusted after the first compensation time.

[0048] Specifically, after obtaining the first control lag time, the hot water flow lag time is compared with the first control lag time. If the hot water flow lag time is greater than the first control lag time, it indicates that the time for the hot water after the temperature change to flow from the water tank temperature sensor 108 to the mixing point 107 is relatively long. If the bypass ratio of the water proportional valve 102 starts to adjust immediately, it will cause water temperature fluctuations. Therefore, the bypass ratio of the water proportional valve 102 is adjusted after the first compensation time to ensure that the gas water heater is in a stable working state. The first compensation time is the difference between the hot water flow lag time and the first control lag time. In this embodiment, the bypass ratio of the water proportional valve 102 is adjusted only after the first compensation time, so that the time for the water proportional valve 102 to complete the adjustment is the same as the time for the hot water flow after the temperature change to reach the mixing point 107. This avoids premature adjustment of the water proportional valve 102, reduces water temperature fluctuations due to repeated adjustments, and improves the constant temperature control effect.

[0049] In one embodiment, the control method for the gas water heater further includes: if the hot water flow lag time is less than or equal to the first control lag time, then immediately adjust the bypass ratio of the water proportional valve.

[0050] Specifically, when the hot water flow lag time is less than or equal to the first control lag time, it indicates that the time for the hot water after the temperature change to flow from the water tank temperature sensor 108 to the mixing point 107 is short. Even if the bypass ratio adjustment of the water proportional valve 102 is started immediately, the hot water after the temperature change has already flowed to the mixing point 107 after the water proportional valve 102 has completed the adjustment. This allows for the mixing adjustment of the hot water after the temperature change, reducing water temperature fluctuations caused by repeated adjustments and improving the constant temperature control effect.

[0051] In one embodiment, such as Figure 4 As shown, step S220, the step of obtaining the lag time of the hot water exchange flow, includes:

[0052] Step S221: Obtain the current total water flow rate, current bypass ratio, and first pipe volume.

[0053] Specifically, the current total water flow rate is detected by the water flow sensor, the current bypass ratio is the current bypass ratio of the water proportional valve 102, and the first pipe volume is the pipe volume from the water tank temperature sensor 108 to the mixing point 107. Its volume is related to the inner diameter of the hot water pipe 104. Since the water tank temperature sensor 108, the mixing point 107, and the hot water pipe 104 are all fixed at the factory, the first pipe volume is a fixed value. It can be stored in the gas water heater's memory, or it can store the distance from the water tank temperature sensor 108 to the mixing point 107 and the inner diameter of the hot water pipe 104. The first pipe volume is automatically calculated by the water heater's control terminal.

[0054] Step S222: Calculate the heat exchanger water flow rate based on the current total water flow rate and the current bypass ratio.

[0055] Specifically, the bypass ratio is the ratio of the water flow rate through the bypass pipe 105 to the total water flow rate. Let the current total water flow rate be L. 总 The current bypass ratio is P1. At this time, the flow rate of the heat exchanger water flowing into heat exchanger 101 is L1 = L 总 *(1-P1).

[0056] Step S223: Calculate the lag time of the hot water flow based on the heat exchanger water flow rate and the volume of the first pipe.

[0057] Specifically, after obtaining the heat exchanger water flow rate L1 and the first pipe volume V1, the heat exchanger water flow lag time TS1 = V1 / L1 = V1 / (L 总 *(1-P1)). It is understood that in some other embodiments, when the hot water pipe 104 is a pipe of uniform diameter, the first pipe volume V1=S1*πR1 2 Where S1 is the length of the hot water flow and R1 is the inner radius of the hot water pipe 104, as shown below. Figure 1 As shown, the hot water flow length S1 is the distance the water flows from the water tank temperature sensor 108 to the mixing point 107.

[0058] In one embodiment, the gas water heater further includes an inlet water temperature sensor, which is located on the bypass pipe 105, at the water distribution point 106, or between the inlet of the cold water pipe 103 and the water distribution point 106, for detecting the inlet water temperature. Figure 5 As shown, the control method for gas water heaters also includes:

[0059] Step S240: Under the condition that the gas water heater is in a stable working state, obtain the water inlet temperature of the water heater.

[0060] Specifically, when a gas water heater is in a stable operating state, it has already established a heat exchange balance, and the actual outlet water temperature generally does not change. When the inlet water temperature of the water heater changes, the heat exchange balance is disrupted, and the control system needs to adjust the bypass ratio of the water proportional valve 102 to bring the gas water heater into a stable operating state. The inlet water temperature is detected by the inlet water temperature sensor.

[0061] Step S250: If the fluctuation value of the water inlet temperature of the water heater is greater than the second preset temperature, then obtain the lag time of the mixed water flow.

[0062] Specifically, when the fluctuation range of the water inlet temperature of the water heater exceeds the second preset temperature (e.g., 1 degree Celsius), it indicates that the water inlet temperature fluctuates significantly, and users can sensitively perceive the fluctuation in the actual outlet water temperature. In this case, the bypass ratio of the water proportional valve 102 needs to be adjusted through subsequent steps. First, the mixing water flow lag time is calculated. The mixing water flow lag time is the time it takes for the water to flow from the inlet water temperature sensor through the bypass pipe 105 to the mixing point 107. The time it takes for the water to flow from the inlet water temperature sensor to the mixing point 107 can be calculated using the current inlet water flow rate and the volume of the pipe through which the water flows.

[0063] Step S260: Adjust the bypass ratio of the water proportioning valve according to the lag time of the mixed water flow.

[0064] Specifically, after obtaining the lag time of the mixed water flow, the adjustment time of the bypass ratio of the control water proportional valve 102 can be flexibly selected according to the specific duration of the lag time. For example, the control of the water proportional valve 102 can be started immediately, or the control of the water proportional valve 102 can be started after a certain delay, so that when the water proportional valve 102 completes the bypass ratio adjustment, the water flow has already flowed through the bypass pipe 105 to the mixing point 107, thereby reducing water temperature fluctuations and improving the constant temperature control effect.

[0065] It should be noted that if the fluctuation range of the water inlet temperature of the water heater is greater than the second preset temperature, it may cause the fluctuation value of the heat exchanger outlet temperature to be greater than the first preset temperature. That is, the water proportional valve 102 may be adjusted twice. After adjusting the bypass ratio of the water proportional valve 102 for the first time through steps S240-S260, the bypass ratio of the water proportional valve 102 is adjusted for the second time through steps S210-S230.

[0066] In one embodiment, such as Figure 6 As shown, in step S260, the adjustment time of the bypass ratio of the water proportional valve is controlled according to the lag time of the mixed water flow, including:

[0067] Step S261: Obtain the second control lag time of the water proportional valve.

[0068] Specifically, the second control lag time is the time from when the control system detects a change in the inlet water temperature of the water heater through the inlet water temperature sensor to when the water proportional valve 102 completes the bypass ratio adjustment. The second control lag time is determined by the signal detection and processing system of the gas water heater and the response time of the water proportional valve 102. It can be obtained through prior experimental detection and stored in the gas water heater's memory for direct retrieval when needed. It is understood that the second control lag time can be the same as the first control lag time.

[0069] Step S262: If the lag time of the mixed water flow is greater than the second control lag time, then the bypass ratio of the water proportional valve is adjusted after the second compensation time.

[0070] Specifically, after calculating the mixing water flow lag time, the lag time is compared with the second control lag time. If the mixing water flow lag time is greater than the second control lag time, it indicates that the time for the cold water after the temperature change to flow from the inlet water temperature sensor through the bypass pipe 105 to the mixing point 107 is relatively long. If the bypass ratio of the water proportional valve 102 starts adjusting immediately, the cold water before the temperature change will participate in the mixing process at the mixing point 107, causing water temperature fluctuations. Therefore, the bypass ratio of the water proportional valve 102 is adjusted after the second compensation time to ensure the gas water heater is in a stable operating state. The second compensation time is the difference between the mixing water flow lag time and the second control lag time. This application starts controlling the bypass ratio of the water proportional valve 102 only after the second compensation time, ensuring that the adjustment time of the water proportional valve 102 is the same as the time for the cold water after the temperature change to flow to the mixing point 107. This avoids premature adjustment of the water proportional valve 102, reduces water temperature fluctuations due to repeated adjustments, and improves the constant temperature control effect. It is understandable that when the inlet water temperature of the water heater changes, the outlet water temperature of the heat exchange tube will also change, thus calculating the first compensation time and the second compensation time. At this time, the longer of the two times is selected to determine the compensation time, and the bypass ratio of the water proportional valve 102 is controlled after the compensation time.

[0071] In one embodiment, the control method for the gas water heater further includes: if the mixing water flow lag time is less than or equal to the second control lag time, then immediately adjusting the bypass ratio of the water proportional valve.

[0072] Specifically, when the mixing water flow lag time is less than or equal to the second control lag time, it indicates that the time for the cold water with the changed temperature to flow from the inlet water temperature sensor through the bypass pipe 105 to the mixing point 107 is relatively short. At this time, the bypass ratio adjustment of the water proportional valve 102 is immediately initiated. After the water proportional valve 102 completes its adjustment, the cold water with the changed temperature has already flowed to the mixing point 107 through the bypass pipe 105, thus adjusting the mixing of the cold water with the changed temperature. It is understandable that when the inlet water temperature of the water heater changes, the outlet water temperature of the heat exchange tube will also change. Therefore, when immediately controlling the water proportional valve 102, the hot water flow lag time and the mixing water flow lag time must be less than or equal to the first control lag time and the second control lag time, respectively. At this time, both the hot water and cold water with the changed temperature can flow to the mixing point 107.

[0073] In one embodiment, such as Figure 7 and Figure 8 As shown, when the inlet water temperature sensor 109 is installed on the bypass pipe 105 or at the water distribution point 106, step S250, the step of obtaining the lag time of the mixed water flow, includes:

[0074] Step S251: Obtain the current total water flow rate, current bypass ratio, and second pipe volume.

[0075] Specifically, the current total water flow rate is detected by the water flow sensor, the current bypass ratio is the current bypass ratio of the water proportional valve 102, and the second pipe volume is the pipe volume from the inlet water temperature sensor 109 to the mixing point 107. Its volume is related to the inner diameter of the cold water pipe 103 and the bypass pipe 105. Since the inlet water temperature sensor 109, the mixing point 107, and the cold water pipe 103 are all fixed at the factory, the second pipe volume is a fixed value. It can be stored in the gas water heater's memory, or it can store the distance from the inlet water temperature sensor 109 to the mixing point 107 and the inner diameter of the bypass pipe 105. The second pipe volume is automatically calculated by the water heater's control terminal.

[0076] Step S252: Calculate the bypass pipe flow rate based on the current total water flow rate and the current bypass ratio.

[0077] Specifically, the bypass ratio is the ratio of the water flow rate through the bypass pipe 105 to the total water flow rate. Let the current total water flow rate be L. 总 The current bypass ratio is P2. At this time, the bypass water flow rate L2 = L in bypass pipe 105. 总 *P2.

[0078] Step S253: Calculate the hot water flow lag time based on the bypass pipe water flow rate and the second pipe volume.

[0079] Specifically, after obtaining the bypass pipe water flow rate L2 and the second pipe volume V2, the hot water flow lag time TS2 = V2 / L2 = V2 / (L 总 *P2). It is understandable that, as Figure 8 As shown, since the inlet water temperature sensor 109 is located on the bypass pipe 105 or at the water distribution point 106, the volume of the second pipe is all or part of the volume of the bypass pipe. When the bypass pipe 105 is a pipe of uniform diameter, the volume of the second pipe is V2 = S2 * πR2. 2 Where S2 is the distance from the inlet water temperature sensor 109 to the mixing point 107, and R2 is the inner radius of the bypass pipe 105.

[0080] In one embodiment, such as Figure 9 and Figure 10 As shown, when the inlet water temperature sensor 109 is located between the inlet and the water distribution point 106, step S250, the step of obtaining the lag time of the mixed water flow, includes:

[0081] Step S254: Obtain the current total water flow rate, current bypass ratio, third pipe volume, and bypass pipe volume.

[0082] Specifically, the current total water flow rate is detected by the water flow sensor, the current bypass ratio is the current bypass ratio of the water proportional valve 102, the third pipe volume is the pipe volume from the inlet water temperature sensor 109 to the water distribution point 106, and its size is related to the inner diameter of the cold water pipe 103. The bypass pipe volume is the total pipe volume of the bypass pipe 105. Since the inlet water temperature sensor 109, the water distribution point 106, the cold water pipe 103, and the bypass pipe 105 are all fixed at the factory, the third pipe volume is a fixed value. It can be stored in the gas water heater's memory, or it can store the distance from the inlet water temperature sensor 109 to the water distribution point 106 and the inner diameter of the cold water pipe 103, and the third pipe volume is automatically calculated by the water heater's control terminal.

[0083] Step S255: Calculate the first time based on the current total water flow and the volume of the third pipe.

[0084] Specifically, the first time is the time it takes for the water to flow from the inlet water temperature sensor 109 to the water distribution point 106, and the current total water flow rate is L. 总 The volume of the third pipe is V3, and the first time interval is T1 = V3 / L. 总 .

[0085] Step S256: Calculate the bypass pipe flow rate based on the current total water flow rate and the current bypass ratio.

[0086] Specifically, the bypass ratio is the ratio of the water flow rate through the bypass pipe 105 to the total water flow rate. Let the current bypass ratio be P3. At this time, the bypass water flow rate into the bypass pipe 105 is L3 = L 总*P3.

[0087] Step S257: Calculate the second time based on the bypass pipe water flow rate and bypass pipe volume.

[0088] Specifically, the second time is the time it takes for the water to flow from the water distribution point 106 to the mixing point 107, which is also the time it takes for the water to flow in the bypass pipe 105. Let the volume of the bypass pipe be V. 旁 The second time T2=V 旁 / L3.

[0089] Step S258: Calculate the lag time of the mixed water flow based on the first time and the second time.

[0090] Specifically, the lag time of the mixed flow is the sum of the first time and the second time, and the lag time of the mixed flow is TS3 = T1 + T2 = V3 / L. 总 +V 旁 / (L) 总 *P3). In one specific embodiment, such as Figure 10 As shown, when both the cold water pipe 103 and the bypass pipe 105 are pipes of uniform diameter, the volume of the third pipe V3 = S3 * πR3 2 bypass pipe volume V 旁 =S4*πR2 2 Where R3 is the inner radius of the cold water pipe 103, and R2 is the inner radius of the bypass pipe 105. At this time, the lag time of the mixed water flow is TS3 = S3 * πR3. 2 / L 总 +S4*πR2 2 / (L 总 *P3).

[0091] In one embodiment, such as Figure 11 and Figure 12 As shown, the gas water heater also includes an inlet water temperature sensor 109, which is installed on the cold water pipe 103 and located between the water distribution point 106 and the heat exchanger 101. The control method for the gas water heater also includes…

[0092] Step S270: When the gas water heater is in a stable working state, obtain the water inlet temperature of the water heater.

[0093] Specifically, when a gas water heater is in a stable operating state, it has already established a heat exchange balance, and the actual outlet water temperature generally does not change. When the inlet water temperature of the water heater changes, the heat exchange balance is disrupted, and the control system needs to adjust the bypass ratio of the water proportional valve 102 to bring the gas water heater into a stable operating state. The inlet water temperature is detected by the inlet water temperature sensor 109.

[0094] Step S280: If the fluctuation range of the water inlet temperature of the water heater is greater than the second preset temperature, then calculate the lag time of the mixed water flow.

[0095] Specifically, when the fluctuation range of the water inlet temperature of the water heater is greater than the second preset temperature (e.g., 1 degree Celsius), it indicates that the water inlet temperature of the water heater fluctuates significantly, and the user can sensitively feel the fluctuation of the actual outlet water temperature. At this time, it is necessary to adjust the bypass ratio of the water proportional valve 102 through subsequent steps. First, calculate the mixing water flow lag time. In this embodiment, the mixing water flow lag time is the difference between the third time and the fourth time. The third time is the time it takes for the water to flow from the water distribution point 106 through the bypass pipe 105 to the mixing point 107, and the fourth time is the time it takes for the water to flow from the water distribution point 106 to the inlet water temperature sensor 109. The third time is greater than the fourth time.

[0096] Step S290: If the lag time of the mixed water flow is greater than the second control lag time, then adjust the bypass ratio of the water proportional valve after the second compensation time.

[0097] Specifically, after calculating the mixing water flow lag time, the lag time is compared with the second control lag time. If the mixing water flow lag time is greater than the second control lag time, it indicates that the time from when the cold water after the temperature change is detected by the inlet water temperature sensor 109 to when it flows to the mixing point 107 through the bypass pipe 105 is relatively long. If the bypass ratio of the water proportional valve 102 is adjusted immediately, the cold water before the temperature change will participate in the mixing process at the mixing point 107, causing water temperature fluctuations. Therefore, after the second compensation time, the bypass ratio of the water proportional valve 102 is adjusted to ensure that the gas water heater is in a stable operating state. The second compensation time is the difference between the mixing water flow lag time and the second control lag time. This application controls the bypass ratio of the water proportional valve 102 only after the second compensation time has elapsed. This ensures that the adjustment time of the water proportional valve 102 is the same as the time it takes for the water flow after the cold water temperature change to reach the mixing point 107. This avoids premature adjustment of the water proportional valve 102, reduces water temperature fluctuations caused by repeated adjustments, and improves the thermostatic control effect. It is understood that when the inlet water temperature of the water heater changes, the outlet water temperature of the heat exchange tube will also change, thus calculating the first compensation time and the second compensation time. The longer of the two times is selected to determine the compensation time, and the bypass ratio of the water proportional valve 102 is controlled after the compensation time.

[0098] Specific examples, such as Figure 12As shown, the inlet water temperature sensor 109 is located between the water distribution point 106 and the heat exchanger 101. The lag time of the mixed water flow is the difference between the third time and the fourth time. The third time is the time it takes for the water to flow from the water distribution point 106 through the bypass pipe 105 to the mixing point 107, and the fourth time is the time it takes for the water to flow from the water distribution point 106 to the inlet water temperature sensor 109. The third time is greater than the fourth time. Specifically, in this embodiment, when the cold water pipe 103 is a pipe of uniform diameter, the third time T3 = S4 * πR2. 2 / (L 总 *P4), S4 is the distance from water distribution point 106 to mixing point 107 via bypass pipe 105, which is also the length of bypass pipe 105, R2 is the inner radius of bypass pipe 105, L 总 P4 represents the current total water flow rate, and P4 represents the current bypass ratio. The fourth time interval is T4 = S5 * πR3. 2 / (L 总 *(1-P4)), where S5 is the distance from the water distribution point 106 to the inlet water temperature sensor 109, and R3 is the inner radius of the cold water pipe 103. Since the mixed water flow lag time is greater than the second control lag time, the mixed water flow lag time is greater than 0. Therefore, the third time is greater than the fourth time. In this case, the mixed water flow lag time TS4 = S4 * πR2 2 / (L 总 *P4)-S5*πR3 2 / (L 总 *(1-P4)).

[0099] It should be understood that although the steps in the flowcharts of the embodiments described above are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the embodiments described above may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the steps or stages of other steps.

[0100] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium. When executed, the computer program can include the processes of the embodiments described above. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM). The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, etc., and are not limited to these.

[0101] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0102] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A control method for a gas water heater, the gas water heater comprising: The system comprises a heat exchanger, a water proportioning valve, a cold water pipe, a hot water pipe, and a bypass pipe. The connection point between the cold water pipe and the bypass pipe is a water distribution point, and the connection point between the hot water pipe and the bypass pipe is a water mixing point. A water tank temperature sensor is installed on the hot water pipe, located between the heat exchanger and the water mixing point. The method is characterized by comprising: When the gas water heater is in a stable working state, the outlet water temperature of the heat exchanger is obtained; If the fluctuation value of the heat exchanger outlet water temperature is greater than the first preset temperature, then the heat exchange water flow lag time is obtained, including: Obtain the current total water flow rate, the current bypass ratio, and the first pipe volume; wherein, the first pipe volume is the pipe volume from the water tank temperature sensor to the mixing point; Calculate the heat exchanger water flow rate based on the current total water flow rate and the current bypass ratio; The heat exchange water flow lag time is calculated based on the heat exchanger water flow rate and the first pipe volume; wherein, the heat exchange water flow lag time is the time it takes for the water to flow from the water tank temperature sensor to the mixing point; The adjustment time of the bypass ratio of the water proportional valve is controlled based on the lag time of the hot water flow, including: Obtain the first control lag time of the water proportional valve; If the hot water flow lag time is greater than the first control lag time, the bypass ratio of the water proportional valve is adjusted after the first compensation time; wherein, the first control lag time is the time from when the water tank temperature sensor detects the change in the outlet water temperature of the heat exchanger to when the water proportional valve completes the bypass ratio adjustment, and the first compensation time is the difference between the hot water flow lag time and the first control lag time. If the hot water flow lag time is less than or equal to the first control lag time, the bypass ratio of the water proportional valve is immediately adjusted.

2. The method of claim 1, wherein, The gas water heater further includes an inlet water temperature sensor, which is located on the bypass pipe or at the water distribution point. The method further includes: When the gas water heater is in a stable operating state, the inlet water temperature of the water heater is obtained; If the fluctuation value of the inlet water temperature of the water heater is greater than the second preset temperature, then the mixed water flow lag time is obtained, including: Obtain the current total water flow rate, the current bypass ratio, and the volume of the second pipe; wherein, the volume of the second pipe is the pipe volume from the inlet water temperature sensor to the mixing point; Calculate the bypass pipe flow rate based on the current total water flow rate and the current bypass ratio; The mixing water flow lag time is calculated based on the bypass pipe water flow rate and the second pipe volume; wherein, the mixing water flow lag time is the time it takes for water to flow from the inlet water temperature sensor through the bypass pipe to the mixing point; The adjustment time of the bypass ratio of the water proportional valve is controlled based on the lag time of the mixed water flow, including: Obtain the second control hysteresis time of the water proportional valve; If the lag time of the mixed water flow is greater than the second control lag time, the bypass ratio of the water proportional valve is adjusted after the second compensation time; wherein, the second compensation time is the difference between the lag time of the mixed water flow and the second control lag time.

3. The method according to claim 2, characterized in that, The method further includes: If the lag time of the mixed water flow is less than or equal to the second control lag time, the bypass ratio of the water proportional valve is immediately adjusted.

4. The method according to claim 2, characterized in that, When the inlet water temperature sensor is located between the inlet and the water distribution point, the step of obtaining the lag time of the mixed water flow includes: Obtain the current total water flow rate, current bypass ratio, third pipe volume, and bypass pipe volume; wherein, the third pipe volume is the pipe volume from the inlet water temperature sensor to the water distribution point; The first time is calculated based on the current total water flow and the volume of the third pipe. Calculate the bypass pipe flow rate based on the current total water flow rate and the current bypass ratio; The second time is calculated based on the water flow rate and volume of the bypass pipe; The lag time of the mixed water flow is calculated based on the first time and the second time.

5. The method according to claim 1, characterized in that, The gas water heater also includes an inlet water temperature sensor, which is installed on the cold water pipe and located between the water distribution point and the heat exchanger. The method further includes... When the gas water heater is in a stable operating state, the inlet water temperature of the water heater is obtained; If the fluctuation range of the water inlet temperature of the water heater is greater than the second preset temperature, then the mixing water flow lag time is calculated; wherein, the mixing water flow lag time is the difference between a third time and a fourth time, the third time is the time it takes for the water to flow from the water distribution point through the bypass pipe to the mixing point, and the fourth time is the time it takes for the water to flow from the water distribution point to the water inlet temperature sensor, and the third time is greater than the fourth time; the third time is calculated from the distance from the water distribution point through the bypass pipe to the mixing point, the inner radius of the bypass pipe, the current total water flow rate, and the current bypass ratio; the fourth time is calculated from the distance from the water distribution point to the water inlet temperature sensor, the inner radius of the cold water pipe, the current total water flow rate, and the current bypass ratio; If the lag time of the mixed water flow is greater than the second control lag time, the bypass ratio of the water proportional valve is adjusted after the second compensation time; wherein, the second compensation time is the difference between the lag time of the mixed water flow and the second control lag time.

Images