A gas water heater control method and a gas water heater

Abstract

The application provides a gas water heater control method and a gas water heater, and belongs to the technical field of water heaters. The method comprises the following steps: when it is detected that the gas water heater is started again within a preset time period after water is turned off, the current water flow of water entering an inlet pipe is obtained; if the current water flow is less than or equal to a preset flow threshold, only a bypass valve is opened, and the heat energy stored in a heat exchanger and a water mixing tank can meet the gap load demand in a heating blank period; if the current water flow is greater than the preset flow threshold, the bypass valve is opened, and a flow limiting valve is controlled to switch to a flow limiting state. After the flow limiting valve is limited, more cold water directly cools the overheated water in the heat exchanger through a bypass pipeline, and the initial temperature rise is inhibited; and the cold water flow entering the heat exchanger is reduced, the gap load demand in the heating blank period is significantly reduced, the heat energy stored in the heat exchanger and the water mixing tank can meet the gap load demand in the heating blank period as much as possible, the occurrence of temperature drop is greatly reduced or eliminated, and the user experience is improved.

Description

Technical Field

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

[0002] Gas water heaters are widely used due to their rapid heating speed. However, a long-standing problem plagues users: during showering, if the water is turned off and combustion stops, hot residual water remains in the heat exchanger and outlet pipe. This residual heat continues to heat the water in the heat exchanger. When the water is turned back on within 1-2 minutes, this residual hot water flows out first, causing temporary overheating. Furthermore, because gas water heaters have a heating gap period, some water is not fully heated and flows out directly, causing a sudden temperature drop, resulting in a poor user experience.

[0003] In existing technologies, to address the temperature fluctuation issue during restart, a solution involves placing a water tank next to the heat exchanger of the gas water heater and installing a bypass pipe between the inlet and outlet water lines. This solution mitigates temperature fluctuations to some extent through energy storage in the water tank and bypass mixing. However, due to product cost and internal space limitations of the water heater, the size of the heat exchanger and water tank is finite. This solution is insufficient for certain operating scenarios of gas water heaters, and during restarts in some operating conditions, a significant energy deficit can occur, leading to a substantial temperature drop and impacting the user experience. Summary of the Invention

[0004] The first technical problem solved by this invention is to provide a gas water heater control method that minimizes temperature fluctuations during the second startup of the gas water heater.

[0005] The second technical problem solved by the present invention is to provide a gas water heater that reduces temperature fluctuations during secondary startup.

[0006] The first technical problem mentioned above is solved by the following technical solution:

[0007] A method for controlling a gas water heater, the gas water heater comprising a bypass pipe and an inlet pipe, a heat exchanger, and an outlet pipe connected in sequence; one end of the bypass pipe is connected to the inlet pipe, and the other end is connected to the outlet pipe; a flow limiting valve is provided on the inlet pipe, the flow limiting valve being located between a first connection position of the inlet pipe and the bypass pipe and a second connection position of the inlet pipe and the heat exchanger; a bypass valve is provided on the bypass pipe; a mixing tank is provided at the connection position of the outlet pipe and the bypass pipe; the method includes:

[0008] When it is detected that the gas water heater is restarted again within a preset time after the water is turned off, the current water flow rate of the water entering the inlet pipe is obtained;

[0009] If the current water flow rate is less than or equal to the preset flow rate threshold, then only the bypass valve is opened;

[0010] If the current water flow rate is greater than the preset flow rate threshold, the bypass valve is opened, and the flow limiting valve is controlled to switch to the flow limiting state.

[0011] Compared with the prior art, the gas water heater control method of the present invention has the following advantages:

[0012] This invention detects the real-time water flow rate during secondary startup and selects a control strategy accordingly. When the flow rate is low, only the bypass valve is opened, and the heat energy stored in the heat exchanger and mixing tank can meet the shortfall load demand during the heating gap period. When the flow rate is high, the bypass valve is opened and the flow-limiting valve is switched to a flow-limiting state to reduce the flow of cold water into the heat exchanger. On the one hand, since the flow-limiting valve is located between the first and second connection positions, the flow-limiting valve allows more cold water to directly cool the superheated water in the heat exchanger through the bypass pipe, suppressing the initial temperature rise. On the other hand, reducing the flow of cold water entering the heat exchanger significantly reduces the shortfall load demand during the heating gap period, ensuring that the heat energy stored in the heat exchanger and mixing tank can meet the shortfall load demand during the heating gap period as much as possible, greatly reducing or eliminating temperature drops. This method helps solve the temperature fluctuation problem during the secondary startup of gas water heaters and significantly improves the user experience.

[0013] In one embodiment, the method further includes:

[0014] Obtain the operating status of the gas water heater during its second startup;

[0015] The flow limiting duration of the flow limiting valve is determined based on the operating status.

[0016] After the current limiting period ends, the current limiting valve is switched to the fully open state.

[0017] In one embodiment, the operating state includes whether it is in the post-cleaning stage after water shut-off, and determining the flow-limiting duration of the flow-limiting valve based on the operating state includes:

[0018] If it is in the post-cleaning stage after the water is turned off, the reference time is determined as the first reference time.

[0019] If it is not in the post-cleaning stage after water is turned off, then the reference duration is determined as the second reference duration;

[0020] The flow-limiting duration of the flow-limiting valve is determined based on the aforementioned reference duration;

[0021] Wherein, the second reference duration is longer than the first reference duration.

[0022] In one embodiment, the operating state further includes the workload of the gas water heater before the water is turned off, and determining the flow-limiting duration of the flow-limiting valve based on the reference duration includes:

[0023] Obtain the operating load of the gas water heater before the water is turned off, and the theoretical minimum load of the gas water heater;

[0024] The current limiting duration is calculated based on the baseline duration, the workload, the theoretical minimum load, and the preset unit load compensation duration. The current limiting duration is positively correlated with the workload.

[0025] In one embodiment, the formula for calculating the rate limiting duration is:

[0026] T L =T B +(W1-W0)×Δt;

[0027] Among them, T L T B The current limiting duration and the reference duration are respectively, W1 and W0 are the working load and the theoretical minimum load, respectively, and Δt is the unit load compensation duration.

[0028] In one embodiment, the workload is calculated using the following formula:

[0029] W1=(T h -T j )×L×P;

[0030] Where W1 is the workload, T h T j The water tank temperature and the inlet water temperature are respectively the water flow rate and the bypass ratio before the water is turned off. The water tank temperature is the temperature of the hot water entering the mixing tank.

[0031] In one embodiment, the operating state also includes the current water flow rate, and the flow restriction duration is positively correlated with the current water flow rate.

[0032] In one embodiment, the operating state also includes the working load of the gas water heater before the water is turned off, and the flow restriction duration is positively correlated with the working load.

[0033] In one embodiment, the operating state includes whether it is in the post-cleaning stage after the water is turned off, and the flow restriction duration corresponding to the post-cleaning stage after the water is turned off is less than the flow restriction duration corresponding to the post-cleaning stage when the water is not turned off.

[0034] The second technical problem mentioned above is solved by the following technical solution:

[0035] A gas water heater includes a controller, a bypass pipe, and an inlet pipe, a heat exchanger, and an outlet pipe connected in sequence. One end of the bypass pipe is connected to the inlet pipe, and the other end is connected to the outlet pipe. A flow limiting valve is provided on the inlet pipe, located between a first connection position between the inlet pipe and the bypass pipe and a second connection position between the inlet pipe and the heat exchanger. A bypass valve is provided on the bypass pipe, and a mixing tank is provided at the connection position between the outlet pipe and the bypass pipe. The controller is connected to the flow limiting valve and the bypass valve respectively, and the controller is used to execute the gas water heater control method as described above.

[0036] Compared with the prior art, the gas water heater of the present invention has the following advantages:

[0037] This invention detects the real-time water flow rate entering the inlet pipe during secondary startup and selects a control strategy accordingly. When the flow rate is low, only the bypass valve is opened, and the heat energy stored in the heat exchanger and mixing tank can meet the shortfall load demand during the heating blank period. When the flow rate is high, the bypass valve is opened and the flow-limiting valve is switched to a flow-limiting state to reduce the flow of cold water into the heat exchanger. On the one hand, since the flow-limiting valve is located between the first and second connection positions, the flow-limiting valve allows more cold water to directly cool the superheated water in the heat exchanger through the bypass pipe, suppressing the initial temperature rise. On the other hand, reducing the flow of cold water entering the heat exchanger significantly reduces the shortfall load demand during the heating blank period, ensuring that the heat energy stored in the heat exchanger and mixing tank can meet the shortfall load demand during the heating blank period as much as possible, greatly reducing or eliminating temperature drops. This method helps solve the temperature fluctuation problem during the secondary startup of gas water heaters and significantly improves the user experience. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1 This is a schematic diagram of the structure of a gas water heater provided in an embodiment of the present invention;

[0040] Figure 2 This is a schematic diagram of a gas water heater control method provided in an embodiment of the present invention;

[0041] Figure 3 This is a schematic diagram of another gas water heater control method provided in an embodiment of the present invention;

[0042] Figure 4This is a schematic diagram of a controller provided in an embodiment of the present invention. Detailed Implementation

[0043] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0044] In the description of this application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0045] The technical solution of the present invention will be illustrated below through specific embodiments.

[0046] This invention provides a method for controlling a gas water heater, which can be executed by the gas water heater. Figure 1 This is a structural diagram of a gas water heater, such as... Figure 1 As shown, the gas water heater specifically includes: a bypass pipe 10 and an inlet pipe 11, a heat exchanger 12, and an outlet pipe 13 connected in sequence; one end of the bypass pipe 10 is connected to the inlet pipe 11, and the other end is connected to the outlet pipe 13; a flow limiting valve 14 is provided on the inlet pipe 11, located between the first connection position of the inlet pipe 11 and the bypass pipe 10 and the second connection position of the inlet pipe 11 and the heat exchanger 12; a bypass valve 15 is provided on the bypass pipe 10; and a mixing tank 16 is provided at the connection position of the outlet pipe 13 and the bypass pipe 10. The function of the mixing tank 16 is to store the hot water flowing out of the heat exchanger 12 and to mix the hot water with the cold water from the bypass pipe 10.

[0047] In addition, such as Figure 1 As shown, the gas water heater also includes a water flow sensor 17, a first temperature sensor 181, a second temperature sensor 182, and a third temperature sensor 183. The water flow sensor 17 is mounted on the inlet pipe 11, located between the inlet and the first connection point, and is used to detect the real-time water flow. The first temperature sensor 181 is located between the inlet and the water flow sensor 17, and is used to detect the inlet water temperature entering the inlet pipe 11. The second temperature sensor 182 is located between the heat exchanger 12 and the mixing tank 16, and is used to detect the tank temperature (i.e., the temperature of the hot water flowing from the heat exchanger 12 into the mixing tank 16). The third temperature sensor 183 is located between the mixing tank 16 and the outlet, and is used to detect the outlet water temperature. The gas water heater also includes a controller (…). Figure 1(Not shown in the image) The controller is connected to the flow limiting valve 14, the bypass valve 15 and various sensors. The controller can control the state switching of the flow limiting valve 14 and the bypass valve 15 and receive signals collected by various sensors.

[0048] Reference Figure 2 The diagram illustrates a gas water heater control method according to an embodiment of the present invention, which may specifically include the following steps:

[0049] S201. When it is detected that the gas water heater is restarted again within a preset time after the water is turned off, the current water flow rate of the water entering the inlet pipe is obtained.

[0050] After the gas water heater is turned off, the heat exchange system (including the heat exchanger and pipes) still retains a certain amount of heat energy, causing the stagnant water in the heat exchange system to continue to be heated and its temperature to rise. If the water is turned off for a longer period than the preset time, the residual heat of the stagnant water will gradually dissipate into the environment, and its temperature will gradually approach the inlet water temperature (usually close to the ambient temperature). Therefore, there is no problem of overheating the water after a second start-up. Thus, whether the preset time after the water is turned off is met is used to determine whether the current situation is a second start-up scenario.

[0051] The preset duration defines the specific time for which the water remaining inside the gas water heater can maintain a temperature significantly higher than the inlet water temperature due to the residual heat from the heat exchange system when the water is turned off. This duration can be determined based on the thermal inertia and heat dissipation characteristics of the gas water heater's heat exchange system. For example, the preset duration can be set within the range of 60 to 120 seconds.

[0052] Because a water flow sensor is installed on the inlet pipe, the controller can monitor the water flow status through the sensor. In the specific judgment process, when the controller detects that the water flow in the inlet pipe changes from a flowing state to a stopped state, it records this as a water shut-off event. A stopped state means that the water flow has stopped or the flow rate is lower than a certain set flow rate value. After a water shut-off event occurs, the controller starts a timer. If, within a preset time period, the controller detects that the water flow in the inlet pipe changes from a stopped state to a flowing state, it determines that the gas water heater has undergone a secondary start-up.

[0053] Upon confirmation of a second startup, the controller acquires the current water flow rate via a water flow sensor installed on the inlet pipe. Specifically, this water flow sensor converts the real-time water flow velocity signal into an electrical signal, and the controller calculates the current water flow rate using appropriate interface circuitry and sampling algorithms.

[0054] S202. Determine whether the current water flow rate is less than or equal to the preset flow rate threshold.

[0055] For a specific model of gas water heater, the volume of its mixing tank and the heat capacity of its heat exchange system are fixed. Therefore, there is an upper limit to the heat energy it can provide. This upper limit determines the maximum instantaneous compensation load that can be provided within this preset time period. The flow rate threshold corresponds to the critical water flow rate corresponding to this maximum instantaneous compensation load, achieving a smooth transition in water temperature. Optionally, the flow rate threshold is 8L / min.

[0056] The flow threshold is stored in the controller. When the current water flow is obtained, the current water flow can be compared with the flow threshold. Specifically, it is determined whether the current water flow is less than or equal to the preset flow threshold. If yes, S203 is executed; otherwise, S204 is executed.

[0057] S203, Only open the bypass valve.

[0058] When the current water flow rate is less than or equal to the preset flow threshold, it indicates that the load demand is within the self-compensation capability of the heat exchange system. The controller sends a control command to the bypass valve, calculates and sets its opening degree in real time based on the target outlet water temperature (e.g., opening to 30%) to achieve water mixing and temperature adjustment. At the same time, the controller does not send any action command to the flow-limiting valve, keeping it in the default fully open state (100% opening), ensuring that the main water path is completely unobstructed.

[0059] Under this strategy, during the initial stage of secondary startup, a small amount of warmer stored water flowing out of the heat exchanger mixes with a small amount of cold water coming through the bypass valve in the mixing tank, resulting in mixed water with a temperature close to the target outlet water temperature. Since the current water flow is low, the power required to heat the newly supplied cold water is low, meaning the shortfall load is small. The heat energy stored in the mixing tank is sufficient to meet the shortfall load requirements during the heating gap period, which is enough to maintain a stable output water temperature temporarily until the burner gradually increases its output power according to control commands, thereby achieving a smooth transition in outlet water temperature.

[0060] S204. Open the bypass valve and control the flow limiting valve to switch to the flow limiting state.

[0061] When the current water flow rate is greater than the preset flow rate threshold, it indicates that the load demand exceeds the self-compensation capacity of the heat exchange system. At this time, the controller sends control commands to the bypass valve and the flow limiting valve.

[0062] For bypass valves, the controller drives the bypass valve to a large opening, such as 80% or fully open. The direct purpose of this operation is to significantly reduce the water flow resistance of the bypass pipe at the moment of startup, creating conditions for subsequent flow distribution.

[0063] Simultaneously, for the flow-limiting valve, the controller drives the valve to switch from the default fully open state to the flow-limiting state. The opening degree corresponding to the flow-limiting state is a preset opening degree, such as 45%. When the flow-limiting valve is in the flow-limiting state, the water flow resistance of the main water circuit is significantly increased, thereby reducing the flow rate of cold water entering the heat exchanger during the heating blank period.

[0064] By opening the bypass valve and switching the flow-limiting valve to the flow-limiting state, the water flow resistance in the bypass pipe is reduced, while the water flow resistance in the main water path is increased. Most of the water flow in the inlet pipe is guided to the low-resistance bypass pipe, while a small portion flows into the heat exchanger through the high-resistance main water path. A large amount of low-temperature bypass cold water mixes with the initial superheated water flowing out of the heat exchanger at the mixing tank inlet, which can quickly cool the initial superheated water and suppress the initial temperature rise. At the same time, the flow rate of cold water entering the heat exchanger that needs to be heated is reduced, and the shortfall load during the heating blank period is significantly reduced or becomes zero. This allows the heat energy stored in the heat exchanger and mixing tank to meet the shortfall load demand during the heating blank period, thereby supporting a smooth transition of the outlet water temperature and significantly reducing or eliminating the possibility of sudden temperature drops.

[0065] This invention detects the real-time water flow rate during secondary startup and selects a control strategy accordingly. When the flow rate is low, only the bypass valve is opened, and the heat energy stored in the heat exchanger and mixing tank can meet the shortfall load demand during the heating gap period. When the flow rate is high, the bypass valve is opened and the flow-limiting valve is switched to a flow-limiting state to reduce the flow of cold water into the heat exchanger. On the one hand, since the flow-limiting valve is located between the first and second connection positions, the flow-limiting valve allows more cold water to directly cool the superheated water in the heat exchanger through the bypass pipe, suppressing the initial temperature rise. On the other hand, reducing the flow of cold water entering the heat exchanger significantly reduces the shortfall load demand during the heating gap period, ensuring that the heat energy stored in the heat exchanger and mixing tank can meet the shortfall load demand during the heating gap period as much as possible, greatly reducing or eliminating temperature drops. This method helps solve the temperature fluctuation problem during the secondary startup of gas water heaters and significantly improves the user experience.

[0066] In an optional embodiment, such as Figure 3 The gas water heater control method shown further includes the following steps after controlling the flow limiting valve to switch to the flow limiting state:

[0067] S301. Obtain the operating status of the gas water heater during secondary startup.

[0068] To ensure that the current limiting duration accurately matches actual demand, the controller needs to collect a set of operating states that define the current operating conditions. These operating states form the basis for dynamic decision-making and primarily characterize the system's immediate readiness and historical load requirements.

[0069] S302. Determine the flow limiting duration of the flow limiting valve based on the operating status.

[0070] Based on the acquired operating status, the controller dynamically calculates an optimal flow-limiting duration using an internally preset control algorithm. This duration determines the length of time the flow-limiting valve remains in the flow-limiting state, with the goal of ensuring that the flow-limiting intervention covers the entire heating delay period until the heat energy output by the gas water heater can independently meet the total load demand for hot water supply.

[0071] S303. After the current limiting time ends, control the current limiting valve to switch to the fully open state.

[0072] When the timer inside the controller reaches the current-limiting duration, it sends a drive command to the current-limiting valve, restoring the valve from its preset opening in the current-limiting state to the default fully open state. At this point, the flow restriction in the main water circuit is lifted, and the gas water heater returns to its normal operating mode, which is controlled by closed-loop feedback from the outlet water temperature. This ensures a long-term constant water temperature supply after the initial stable water temperature transition during startup.

[0073] In an optional embodiment, the operating status includes whether it is in the post-cleaning stage after water shut-off. The flow-limiting duration of the flow-limiting valve is determined based on the operating status, including:

[0074] If the water is shut off and the cleaning process is in progress, the reference duration is determined as the first reference duration; if the water is not shut off and the cleaning process is in progress, the reference duration is determined as the second reference duration; the flow restriction duration of the flow restrictor is determined based on the reference duration; wherein, the second reference duration is longer than the first reference duration.

[0075] When the gas water heater is turned off, the gas supply is also cut off. The controller will start the cleaning program, and the fan will run continuously for tens of seconds to several minutes to exhaust the residual exhaust gas outdoors, ensuring safe use and extending the life of the equipment.

[0076] When a gas water heater is in the post-purge phase, the fan is still running at high speed, and the exhaust gas passage is unobstructed. Therefore, during a second start-up, the burner can achieve rapid ignition (e.g., within 0.5-0.6 seconds). This shortens the heating gap period, reducing the shortfall load that the heat exchange system needs to compensate for, thus allowing for a shorter baseline duration to cover the heating gap period. Conversely, when starting outside the post-purge phase, the fan needs to accelerate from a standstill and ignite only after completing the pre-purge. This results in a longer ignition sequence (e.g., 1.5-1.8 seconds), leading to heating delay and a larger energy gap. Therefore, a longer baseline duration is required to ensure that the flow-limiting effect is maintained throughout the entire heating delay period.

[0077] The duration of the post-cleaning phase is a preset fixed duration, such as 3 minutes. When the gas water heater is turned off, the controller starts timing and determines whether it is in the post-cleaning phase based on the duration of the timing. If it is determined to be in the post-cleaning phase, a shorter first reference duration is determined; if it is determined not to be in the post-cleaning phase, a longer second reference duration is determined.

[0078] The selected baseline duration will serve as the time basis for calculating the final current limiting duration. In other words, the final current limiting duration is derived from this baseline duration, with appropriate compensation or adjustment based on other operating status parameters (such as load demand).

[0079] This embodiment determines the real-time readiness status of the heat exchange system based on the ignition timing during secondary startup (whether it is in the post-purge phase), selects different reference durations, and adaptively adjusts the flow restriction duration accordingly. This reduces temperature fluctuations while minimizing the flow restriction time, further optimizing the user experience and improving the energy efficiency of the gas water heater.

[0080] In an optional embodiment, the operating state also includes the workload of the gas water heater before the water is turned off, and the flow-limiting duration of the flow-limiting valve is determined based on a reference duration, including:

[0081] Obtain the operating load of the gas water heater before the water is turned off, as well as the theoretical minimum load of the gas water heater; calculate the current limiting time based on the reference duration, operating load, theoretical minimum load, and preset unit load compensation time. The current limiting time is positively correlated with the operating load.

[0082] This embodiment, based on the previous embodiment, further refines how to accurately calculate the flow-limiting duration based on the user's historical demand intensity, thereby enabling the control strategy to have personalized adaptive capabilities.

[0083] In this embodiment, the operating state further includes the working load of the gas water heater before the water is turned off. Simultaneously, the controller also needs to call the theoretical minimum load of the gas water heater. First, the load difference between the aforementioned working load and the theoretical minimum load is calculated. This load difference represents the portion of the actual load demand during the user's last stable use that exceeds the theoretical minimum load of the gas water heater, i.e., the shortfall load. Then, the total current-limiting duration is calculated. The current-limiting duration is equal to the base duration plus a compensation time proportional to the load difference.

[0084] The theoretical minimum load is defined as the minimum load that the gas water heater theoretically needs to provide at the initial moment of a secondary start-up, when the flow-limiting valve has switched to the flow-limiting state. The theoretical minimum load is a constant pre-calibrated based on the system characteristics of the gas water heater. Its setting method includes: first, calculating the initial value of the theoretical minimum load W0 based on the minimum water flow rate of the flow-limiting valve in the flow-limiting state and the minimum allowable stable temperature rise of the gas water heater; then, conducting a closed-loop experiment at a key minimum stable operating point: after stable operation at this point, optimizing and adjusting the value of W0 through a secondary start-up test to ensure that the flow-limiting duration output by the control model reaches its optimal value, thereby determining the final calibrated value of W0. The minimum stable operating point refers to the minimum load condition under which the water heater can operate stably after normal start-up (non-secondary start-up), such as the lowest set temperature and the corresponding minimum stable water flow rate.

[0085] In an optional embodiment, the formula for calculating the rate limiting duration is:

[0086] T L =T B +(W1-W0)×Δt;

[0087] Among them, T L T B These represent the flow restriction duration and the baseline duration, respectively. W1 and W0 represent the working load and theoretical minimum load before water shut-off, respectively. Δt represents the unit load compensation duration.

[0088] The unit load compensation time (Δt) is a preset constant, determined experimentally. Specifically, by shutting off the gas water heater under different operating loads and then restarting it a second time within a preset time after shutting off (where the current water flow rate during the second restart is greater than a preset flow threshold), with the bypass valve opened and the flow limiting valve switched to flow limiting mode, the time from the second restart until the outlet water temperature stabilizes is recorded as the flow limiting time. This determines the relationship between each operating load and the corresponding flow limiting time. Under this calculation model, the larger the operating load (W1) before shutting off, the larger the difference between it and the theoretical minimum load (W0), and the longer the calculated compensation time, ultimately leading to a longer total flow limiting time (T). L The corresponding extension means that the higher the load used by the user last time, the greater the total load required. Therefore, during the second startup, the load gap that needs to be compensated to reach the same steady state is also greater. Thus, it is necessary to extend the current limiting time to maintain the load reduction state for a longer period of time to ensure that the energy stored in the mixing tank is sufficient to fill this larger gap.

[0089] In this embodiment, by introducing a quantitative load difference compensation mechanism, the control algorithm can not only respond to the ignition preparation state (whether it is the post-purge stage), but also adaptively adjust the current-limiting duration according to the personalized historical load demands of different users, significantly improving the control accuracy and the user's constant temperature experience.

[0090] In an optional embodiment, the calculation formula for the working load is:

[0091] W1 = (T h - T j ) × L × P;

[0092] Where, W1 is the working load, T h , T j are the water tank temperature before closing the water and the inlet water temperature in sequence, L and P are the water flow rate before closing the water and the bypass ratio respectively. 0 < P < 1, which reflects the opening degree of the bypass valve at that time. Among them, the water tank temperature is the temperature of the hot water flowing out of the heat exchanger and entering the mixing tank.

[0093] Specifically, P = 1 - (T c - T j ) / (T h - T j );

[0094] T h = (T c - T j ) / (1 - P);

[0095] Where, T c is the target outlet water temperature.

[0096] In specific implementation, at the moment when the user closes the water, the controller will quickly collect the real-time sensor values or calculation results of T h , T j , L and P at this moment, and substitute them into this formula to calculate the W1 value and store it in the memory, as the core basis for predicting the load demand during the subsequent secondary startup. This makes the working load change from an abstract concept to a computable parameter, ensuring the accuracy and repeatability of the control algorithm.

[0097] In an optional embodiment, the operating state further includes the current water flow rate, and the current-limiting duration is positively correlated with the current water flow rate.

[0098] To achieve the above positive correlation control, any of the following specific methods can be adopted:

[0099] Mapping query method: A water flow rate - current-limiting duration mapping table or function curve is pre-stored in the controller. After obtaining the current water flow rate, directly query this mapping relationship to match the corresponding current-limiting duration.

[0100] Baseline adjustment method: Current limiting duration (T) L ) through formula T L = T B + f(L) is calculated, where T B Let L be the base duration, L be the current water flow rate, and f(L) be a compensation function that monotonically increases with the current water flow rate L. This method also directly establishes a direct proportional relationship between the current water flow rate and the final duration.

[0101] This embodiment does not rely on the calculation and memory of historical loads, but directly responds to the immediate water demand during the second startup. By establishing a direct positive correlation between the current water flow and the flow restriction duration, it can ensure that under high flow demand, the flow restriction duration can be automatically extended to compensate for the larger instantaneous energy gap; under low flow demand, the flow restriction duration is shortened accordingly to avoid excessive flow restriction, which is especially suitable for scenarios with a large number of users or changing water usage habits.

[0102] In an optional embodiment, the operating state also includes the workload of the gas water heater before the water is turned off, and the flow restriction duration is positively correlated with the workload.

[0103] The operating load refers to the historical operating status of the gas water heater, and predictive control is performed based on this historical operating status. The current limiting duration should be positively correlated with the operating load before the water is turned off. That is, the higher the operating load value before the water is turned off, the longer the calculated or set current limiting duration should be; conversely, the lower the load value, the shorter the current limiting duration should be.

[0104] The workload of a user before turning off the water directly reflects their preference for hot water intensity. A higher workload indicates that the user tends to use a larger flow rate or a higher temperature of hot water, resulting in a higher thermal energy demand for the desired state. Consequently, during a second startup, the system experiences a larger thermal energy gap when recovering from the current state to the user's desired state. Therefore, it is necessary to extend the flow restriction duration to maintain active load reduction for a longer period, ensuring that the thermal energy stored in the mixing tank is sufficient to fill this thermal energy gap and achieve a smooth transition in outlet water temperature.

[0105] In an optional embodiment, the operating state includes whether it is in the post-cleaning stage after water shut-off, and the flow restriction duration corresponding to the post-cleaning stage after water shut-off is less than the flow restriction duration corresponding to the post-cleaning stage not in the post-cleaning stage after water shut-off.

[0106] This embodiment clarifies the method for determining the required flow restriction time of a gas water heater under different ignition times (whether or not it is in the post-cleaning phase after the water is turned off). When it is in the post-cleaning phase after the water is turned off, the determined or adopted flow restriction time should be less than the flow restriction time corresponding to when it is not in the post-cleaning phase.

[0107] During the post-purge phase, the fan continues to operate at high speed to remove exhaust gases, and the combustion chamber is well-ventilated. Secondary ignition in this state eliminates the time required for the fan to accelerate from standstill to rated speed, and since the combustion chamber conditions are nearly ready, rapid ignition (e.g., within 0.5 to 0.6 seconds) is possible. Rapid flame establishment means a significantly shorter heating gap and reduced system load deficit. Therefore, the flow restriction duration used to cover this brief heating gap and balance the load can be correspondingly shortened.

[0108] During the non-post-purge phase, the fan has already stopped. Upon restarting, the entire ignition sequence must be executed from the beginning, including fan start-up, speed establishment, and pre-purge, resulting in a significant increase in ignition delay (e.g., 1.5 to 1.8 seconds). A longer heating gap means a larger cumulative energy deficit; therefore, a longer flow restriction duration must be employed to ensure continuous cold water flow restriction throughout the delay period, providing sufficient heating start-up time for the gas water heater.

[0109] It should be noted that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0110] Corresponding to the above-described gas water heater control method, this invention also provides a gas water heater, comprising a controller, a bypass pipe, and an inlet pipe, a heat exchanger, and an outlet pipe connected in sequence; one end of the bypass pipe is connected to the inlet pipe, and the other end is connected to the outlet pipe; a flow limiting valve is provided on the inlet pipe, the flow limiting valve being located between a first connection position of the inlet pipe and the bypass pipe and a second connection position of the inlet pipe and the heat exchanger; a bypass valve is provided on the bypass pipe; a mixing tank is provided at the connection position of the outlet pipe and the bypass pipe; the controller is connected to the flow limiting valve and the bypass valve respectively; the controller is used to execute any of the gas water heater control methods in the embodiments of this invention; the specific structure of the gas water heater can be referred to... Figure 1 ( Figure 1 (Controller not shown) and related Figure 1 The relevant descriptions will not be elaborated here.

[0111] Reference Figure 4 The diagram illustrates a controller according to an embodiment of the present invention. The controller includes:

[0112] The current water flow acquisition module 401 is used to acquire the current water flow of water entering the inlet pipe when it is detected that the gas water heater is restarted again within a preset time after the water is turned off.

[0113] The first control module 402 is used to open only the bypass valve if the current water flow rate is less than or equal to a preset flow rate threshold.

[0114] The second control module 403 is used to open the bypass valve and control the flow limiting valve to switch to the flow limiting state if the current water flow rate is greater than the preset flow threshold.

[0115] Optionally, the controller further includes:

[0116] The operating status acquisition module is used to acquire the operating status of the gas water heater during its second startup.

[0117] The current limiting duration calculation module is used to determine the current limiting duration of the current limiting valve based on the operating status.

[0118] The switching module is used to control the flow limiting valve to switch to the fully open state after the flow limiting time ends.

[0119] Optionally, the operating status includes whether it is in the post-cleaning stage after water shut-off, and the flow restriction duration calculation module includes:

[0120] The first reference duration determination unit is used to determine the reference duration as the first reference duration if the cleaning stage after water shut-off is in progress.

[0121] The second reference duration determination unit is used to determine the reference duration as the second reference duration if the post-cleaning stage after water shut-off is not in progress.

[0122] A current-limiting duration calculation unit is used to determine the current-limiting duration of the current-limiting valve based on the reference duration;

[0123] Wherein, the second reference duration is longer than the first reference duration.

[0124] Optionally, the operating state also includes the working load of the gas water heater before the water is turned off, and the current limiting duration calculation unit is used for:

[0125] Obtain the operating load of the gas water heater before the water is turned off, and the theoretical minimum load of the gas water heater;

[0126] The current limiting duration is calculated based on the baseline duration, the workload, the theoretical minimum load, and the preset unit load compensation duration. The current limiting duration is positively correlated with the workload.

[0127] Optionally, the formula for calculating the current limiting duration is:

[0128] T L =T B +(W1-W0)×Δt;

[0129] Among them, T L T B The current limiting duration and the reference duration are respectively, W1 and W0 are the working load and the theoretical minimum load, respectively, and Δt is the unit load compensation duration.

[0130] Optionally, the formula for calculating the workload is:

[0131] W1=(T h -T j )×L×P;

[0132] Where W1 is the workload, T h T j The water tank temperature and the inlet water temperature are respectively the water flow rate and the bypass ratio before the water is turned off. The water tank temperature is the temperature of the hot water entering the mixing tank.

[0133] Optionally, the operating status also includes the current water flow rate, and the flow restriction duration is positively correlated with the current water flow rate.

[0134] Optionally, the operating state also includes the working load of the gas water heater before the water is turned off, and the flow restriction duration is positively correlated with the working load.

[0135] Optionally, the operating state includes whether it is in the post-cleaning stage after the water is turned off, and the flow restriction time corresponding to the post-cleaning stage after the water is turned off is less than the flow restriction time corresponding to the post-cleaning stage when the water is not turned off.

[0136] The controller in the gas water heater provided in the embodiments of the present invention can be used to implement the various steps in the aforementioned embodiments of the gas water heater control methods.

[0137] It should be noted that the module division in the various controllers provided in the above embodiments is illustrative and only represents one logical functional division. In actual implementation, other division methods are also possible. Furthermore, the functional modules in the various embodiments of this invention can be integrated into a single processor, exist as separate physical entities, or be integrated into a single module. The integrated modules described above can be implemented in hardware or as software functional modules.

[0138] If the integrated module is implemented as a software functional module and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, all or part of the technical solution of the embodiments of the present invention can be embodied in the form of a computer program product, which is stored in a computer storage medium and includes several instructions to cause an electronic device or processor to execute all or part of the steps of the methods in the various embodiments of the present invention. The aforementioned computer storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0139] Furthermore, the gas water heater and the gas water heater control method embodiments provided in the above embodiments belong to the same concept, and their specific implementation process can be found in the method embodiments, which will not be repeated here.

[0140] The embodiments described above are only used to illustrate the technical solutions of this application, and are not intended to limit it. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A method for controlling a gas water heater, characterized in that, The gas water heater includes a bypass pipe and an inlet pipe, a heat exchanger, and an outlet pipe connected in sequence; one end of the bypass pipe is connected to the inlet pipe, and the other end is connected to the outlet pipe; a flow-limiting valve is provided on the inlet pipe, the flow-limiting valve being located between a first connection position of the inlet pipe and the bypass pipe and a second connection position of the inlet pipe and the heat exchanger; a bypass valve is provided on the bypass pipe; a mixing tank is provided at the connection position of the outlet pipe and the bypass pipe; the method includes: When it is detected that the gas water heater is restarted again within a preset time after the water is turned off, the current water flow rate of the water entering the inlet pipe is obtained; If the current water flow rate is less than or equal to the preset flow rate threshold, then only the bypass valve is opened; If the current water flow rate is greater than the preset flow rate threshold, the bypass valve is opened and the flow limiting valve is controlled to switch to the flow limiting state to obtain the operating status of the gas water heater during the second start-up; the flow limiting duration of the flow limiting valve is determined according to the operating status; after the flow limiting duration of the flow limiting valve ends, the flow limiting valve is controlled to switch to the full-flow state.

2. The method according to claim 1, characterized in that, The operating status includes whether it is in the post-cleaning stage after water shut-off. Determining the flow-limiting duration of the flow-limiting valve based on the operating status includes: If it is in the post-cleaning stage after the water is turned off, the reference time is determined as the first reference time. If it is not in the post-cleaning stage after water is turned off, then the reference duration is determined as the second reference duration; The flow-limiting duration of the flow-limiting valve is determined based on the aforementioned reference duration; Wherein, the second reference duration is longer than the first reference duration.

3. The method according to claim 2, characterized in that, The operating state also includes the workload of the gas water heater before the water is turned off, and determining the flow-limiting duration of the flow-limiting valve based on the reference duration includes: Obtain the operating load of the gas water heater before the water is turned off, and the theoretical minimum load of the gas water heater; The current limiting duration is calculated based on the baseline duration, the workload, the theoretical minimum load, and the preset unit load compensation duration. The current limiting duration is positively correlated with the workload.

4. The method according to claim 3, characterized in that, The formula for calculating the current limiting duration is: T L =T B +(W1-W0)×Δt; Among them, T L T B The current limiting duration and the reference duration are respectively, W1 and W0 are the working load and the theoretical minimum load, respectively, and Δt is the unit load compensation duration.

5. The method according to claim 3, characterized in that, The formula for calculating the workload is: W1=(T h -T j )×L×P; Where W1 is the workload, T h T j The water tank temperature and the inlet water temperature are respectively the water flow rate and the bypass ratio before the water is turned off. The water tank temperature is the temperature of the hot water entering the mixing tank.

6. The method according to claim 1, characterized in that, The operating status also includes the current water flow rate, and the flow restriction duration is positively correlated with the current water flow rate.

7. The method according to claim 1, characterized in that, The operating status also includes the working load of the gas water heater before the water is turned off, and the flow restriction duration is positively correlated with the working load.

8. The method according to claim 1, characterized in that, The operating status includes whether it is in the post-cleaning stage after water shut-off. The flow restriction duration corresponding to the post-cleaning stage after water shut-off is less than the flow restriction duration corresponding to the post-cleaning stage not being in the post-cleaning stage after water shut-off.

9. A gas water heater, characterized in that, The device includes a controller, a bypass pipe, and an inlet pipe, a heat exchanger, and an outlet pipe connected in sequence. One end of the bypass pipe is connected to the inlet pipe, and the other end is connected to the outlet pipe. A flow-limiting valve is provided on the inlet pipe, located between a first connection position between the inlet pipe and the bypass pipe and a second connection position between the inlet pipe and the heat exchanger. A bypass valve is provided on the bypass pipe, and a mixing tank is provided at the connection position between the outlet pipe and the bypass pipe. The controller is connected to both the flow-limiting valve and the bypass valve. The controller is used to execute the gas water heater control method as described in any one of claims 1-8.

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