A control method of a gas water heating system and the gas water heating system

Abstract

The present application relates to the field of residential hot water supply system, and specifically discloses a control method of a gas hot water system and the gas hot water system, which is used for controlling the gas hot water system with a memory alloy one-way valve, comprising: obtaining the current water flow of the gas hot water system; when the current water flow is greater than or equal to a water flow threshold, executing cycle heating; when the current water flow is less than the water flow threshold, executing the following steps: detecting the water flow temperature; when the water flow temperature does not reach a preset temperature threshold, continuing to execute cycle heating; when the water flow temperature reaches the preset temperature threshold, calculating the current water flow frequency, and controlling the working state of cycle heating according to the current water flow frequency. The beneficial technical effects of the present application include: by virtue of the property that the water flow temperature affects the valve opening of the memory alloy one-way valve, the main control logic for optimizing the working state of the cycle heating of the gas hot water system is controlled, the hot water in the cold water pipeline is reduced, and the energy consumption is reduced.

Description

Technical Field

[0001] This invention relates to the field of residential hot water supply systems, and more specifically to a control method for a gas-fired hot water system. Background Technology

[0002] A gas water heater is a type of water heater that uses gas as a heat source. Its working principle is to generate heat through the combustion of gas to heat water to a set temperature for household use. Gas water heaters have advantages such as a large hot water supply, ease of use, and small footprint, making them one of the main devices for household hot water supply. Most gas water heaters on the market today are zero-cold-water type, which use a water pump to circulate and heat water within the pipes for rapid hot water supply. Furthermore, most existing gas water heating systems only have a simple one-way valve between the hot and cold water pipes to prevent cold water from flowing back into the hot water pipes.

[0003] In installation scenarios, zero-cold-water gas water heaters typically exist in two states: with and without a return water pipe. With a return water pipe, hot water can form an internal circulation with the machine through a separate return water pipe, thus preventing hot water from flowing into the cold water pipe. This method is convenient for households, but requires the additional installation of a return water pipe, increasing installation costs. Without a return water pipe, the entire circulation system needs to use the cold water pipe as a return water pipe, which can lead to hot water flowing into the cold water pipe. This can affect the lifespan of the water purifier in the cold water pipe. Because the water purifier needs to filter and purify cold water, circulating and heating the water will degrade the filtered water quality, thus affecting the purifier's lifespan. Furthermore, existing gas water heating systems without a return water pipe typically use a technology that continuously burns gas to circulate and heat the water in the pipe during the internal circulation process to achieve the "zero-cold-water" function. This means that even if the water terminal is not turned on for a long time, hot water will continue to flow in the internal circulation, resulting in gas waste. Summary of the Invention

[0004] The technical problem to be solved by this invention is that current zero-cold-water gas water heaters have the technical problem of hot water flowing into the cold water pipe and high gas consumption when there is no return water pipe. This invention proposes a control method and a gas water heating system, which aims to reduce the hot water in the cold water pipe, reduce the impact of the circulation system on the water purifier in the cold water pipe, and reduce gas consumption.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: a control method for a gas-fired hot water system, used for controlling a gas-fired hot water system employing a shape memory alloy check valve, comprising the following steps:

[0006] Step S1: Determine the flow rate threshold based on the flow rate during the historical operation of the gas-fired hot water system;

[0007] Step S2: Obtain the current water flow rate of the gas-fired hot water system. When the current water flow rate is greater than or equal to the water flow rate threshold, perform cyclic heating. When the current water flow rate is less than the water flow rate threshold, perform the following steps:

[0008] Step S3: Detect the water flow temperature. If the water flow temperature does not reach the preset temperature threshold, continue to perform cyclic heating. When the water flow temperature reaches the preset temperature threshold, calculate the current water flow frequency and control the working state of cyclic heating according to the current water flow frequency.

[0009] Among them, the shape memory alloy check valve is a type of check valve with a shape memory effect. Besides preventing cold water from flowing back into hot water pipes, the shape memory alloy check valve can also quickly change its valve opening according to changes in water temperature. It exhibits good elasticity and recovery performance within a certain temperature range, and the valve opening determines the flow rate through the shape memory alloy check valve. Therefore, by using this shape memory alloy check valve, the flow rate in the pipeline can quickly respond to changes in water temperature, and the unidirectional flow of water in the pipeline can be accurately controlled.

[0010] By determining the water flow threshold based on the historical water flow rate during the operation of the gas water heater, and controlling the circulating heating state of the water heater from multiple dimensions, gas consumption is significantly reduced compared to the existing gas water heating system's continuous circulating heating scheme. Simultaneously, by detecting the water flow temperature and influencing the opening of the shape memory alloy check valve based on the water flow temperature, the frequency of water flow within the gas water heating system pipeline is affected. The circulating heating state is then controlled based on the changes in the pipeline's water flow frequency. After the water in the gas water heating system pipeline has completely heated the entire hot water pipeline and passed through the shape memory alloy check valve, the valve opening rapidly decreases, causing a sharp drop in water flow. This change in flow frequency allows the circulating heating state of the gas water heating system to be stopped based on the current flow frequency. This ensures that the end of the shape memory alloy check valve facing the hot water pipeline is hot water, while the end facing the cold water pipeline is cold water, significantly reducing the amount of hot water flowing from the hot water pipeline into the cold water pipeline, thereby reducing the impact of the circulating heating system on the water purifier in the cold water pipeline.

[0011] Preferably, the shape memory alloy check valve uses a shape memory alloy spring as the valve sealing actuator, and the method for obtaining the preset temperature threshold includes:

[0012] Obtain the maximum elastic force of the shape memory alloy spring and the minimum compression of the shape memory alloy spring when the valve opening is minimum;

[0013] Divide the maximum elastic force by the minimum compression to obtain the maximum elastic force coefficient of the memory alloy spring;

[0014] Based on the properties of the selected memory alloy spring, a temperature threshold is selected that matches the maximum elastic coefficient of the memory alloy spring.

[0015] When a shape memory alloy spring is used as the valve-closing actuator, when the water temperature passing through the check valve is lower than the preset temperature threshold, the spring force coefficient of the valve-closing actuator is small, and the compression of the valve-closing actuator along the water flow direction is L1, and the check valve is in the open valve port state; when the water temperature in the water tank reaches above the preset temperature threshold, the spring force coefficient of the valve-closing actuator is large, and the compression of the valve-closing actuator along the water flow direction decreases to L2, causing the valve-closing actuator to move towards the hot water pipe and block the valve port, resulting in a sharp decrease in the water flow at the outlet of the check valve.

[0016] Preferably, the method for obtaining the maximum elastic force of the shape memory alloy spring includes:

[0017] The pressure in the water heater pipes is monitored in real time after the water pump starts, and recorded as F. 压 Then F at the maximum valve opening 压 This is the maximum elastic force of the memory alloy spring.

[0018] Preferably, in step S3, the method for calculating the current flow frequency includes:

[0019] Obtain the water flow rate at each moment during the operation of the gas water heater;

[0020] The average water flow rate during the current time period during the operation of the gas water heater is determined based on the water flow rate at each moment during the operation of the gas water heater.

[0021] The current flow rate frequency is calculated based on the average flow rate.

[0022] Preferably, the current flow rate frequency is calculated using the following formula:

[0023] F = 8.1 × Q - 3

[0024] Where F represents the current water flow frequency, and Q represents the average water flow during the current time period while the gas water heater is running.

[0025] Preferably, in step S3, the method for controlling the operating state of the circulating heating according to the current water flow frequency includes:

[0026] If the current water flow frequency is greater than or equal to the preset frequency threshold, the cycle heating will continue; if the current water flow frequency is less than the preset frequency threshold, the cycle heating will stop.

[0027] Preferably, in step S1, the method for determining the water flow threshold based on the water flow during the historical operation of the gas water heater includes:

[0028] Obtain the water flow rate at each moment during the historical operation of the gas water heater;

[0029] The average flow rate over multiple time periods during the historical operation is determined based on the water flow rate at each moment during the historical operation.

[0030] The flow rate threshold is calculated based on the average flow rate over the multiple time periods.

[0031] Preferably, the method for calculating the flow rate threshold based on the average flow rate over the multiple time periods includes:

[0032] The minimum value among the average flow rates of the multiple time periods is selected, and the minimum value is multiplied by a preset coefficient ratio to obtain the flow rate threshold.

[0033] A gas-fired hot water system for executing a control method for a gas-fired hot water system as described above, comprising:

[0034] A gas water heater, comprising a water pump assembly, a water flow detection unit, a water temperature detection unit, and a main controller, wherein the water pump assembly provides power for the circulating heating of the gas water heater, the water flow detection unit acquires the water flow rate at each moment during the operation of the gas water heating system, and the water temperature detection unit detects the water flow temperature; the water pump assembly, the water flow detection unit, and the water temperature detection unit are all electrically connected to the main controller.

[0035] Hot water pipe and cold water pipe, wherein the hot water pipe is connected to the outlet of the gas water heater and the cold water pipe is connected to the inlet of the gas water heater;

[0036] A shape memory alloy check valve connects the hot water pipe and the cold water pipe to form a circulating water circuit;

[0037] The shape memory alloy check valve uses a shape memory alloy spring as the valve sealing drive component.

[0038] Preferably, the hot water pipe is equipped with a pressure detection unit, which is used to detect the pressure in the gas-fired hot water system pipe.

[0039] The beneficial technical effects of this invention include: It employs a control method and system for a gas-fired hot water system. By utilizing the properties of a shape memory alloy check valve and optimizing the main control logic, it controls the circulating heating operation of the water heater from three dimensions: water flow rate, water temperature, and water flow frequency. Compared to existing gas-fired hot water systems that continuously perform circulating heating, this method reduces the number of times the gas water heater operates in internal circulation mode while maintaining the water temperature in the hot water pipes, significantly reducing gas consumption. By detecting the water temperature and influencing the valve opening of the shape memory alloy check valve based on the water temperature, it affects the water flow frequency in the gas-fired hot water system pipes. Furthermore, it controls the circulating heating operation based on changes in the water flow frequency in the pipes, ensuring that the water temperature in the gas-fired hot water system pipes... After the water has heated the entire hot water pipe and passed through the shape memory alloy check valve, the valve opening rapidly decreases, resulting in a sharp drop in water flow. This change in flow frequency allows the gas water heating system to stop circulating heating based on the current flow frequency. This ensures that the end of the shape memory alloy check valve facing the hot water pipe is hot water, while the end facing the cold water pipe is cold water. This significantly reduces the amount of hot water flowing from the hot water pipe into the cold water pipe, thereby reducing the impact of the circulating heating system on the water purifier in the cold water pipe. By using a shape memory alloy spring as the valve-closing actuator, and leveraging the relationship between the spring force coefficient and temperature, the shape memory alloy check valve achieves adaptive control at different temperatures, making the circulating heating of the gas water heating system more efficient.

[0040] Other features and advantages of the present invention will be disclosed in detail in the following detailed description and accompanying drawings. Attached Figure Description

[0041] The invention will be further described below with reference to the accompanying drawings:

[0042] Figure 1 This is a flowchart of a control method for a gas water heater according to an embodiment of the present invention.

[0043] Figure 2 This is a flowchart illustrating the method for obtaining the preset temperature threshold of smoke according to an embodiment of the present invention.

[0044] Figure 3 This is a schematic diagram illustrating the relationship between the elastic coefficient of the shape memory alloy spring and the water temperature in an embodiment of the present invention.

[0045] Figure 4 This is a schematic diagram illustrating the relationship between water temperature and water flow rate in an embodiment of the present invention.

[0046] Figure 5 This is a schematic diagram illustrating the working principle of the shape memory alloy check valve under different water flow temperatures and flow rates according to an embodiment of the present invention.

[0047] Figure 6This is a flowchart illustrating the working state of the gas water heater's circulating heating according to an embodiment of the present invention.

[0048] Figure 7 This is a structural schematic diagram of a gas water heater according to an embodiment of the present invention.

[0049] The components include: 1. Water volume detection unit, 2. Hot water pipeline, 3. Cold water pipeline, 4. Water pump assembly, 5. Main controller, 6. Shape memory alloy check valve, and 7. Shape memory alloy spring. Detailed Implementation

[0050] The technical solutions of the embodiments of the present invention will be explained and described below with reference to the accompanying drawings. However, the following embodiments are only preferred embodiments of the present invention and not all of them. Other embodiments obtained by those skilled in the art based on the embodiments in the implementation methods without creative effort are all within the protection scope of the present invention.

[0051] In the following description, terms such as “inner,” “outer,” “upper,” “lower,” “left,” and “right” are used only to facilitate the description of embodiments and simplify the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0052] Example 1:

[0053] This application provides a control method for a gas-fired hot water system, specifically for controlling a gas-fired hot water system employing a shape memory alloy check valve 6. Please refer to the attached document. Figure 1 This includes the following steps:

[0054] Step S1: Determine the flow rate threshold based on the flow rate during the historical operation of the gas-fired hot water system.

[0055] Step S2: Obtain the current water flow rate of the gas-fired hot water system. When the current water flow rate is greater than or equal to the water flow rate threshold, perform cyclic heating. When the current water flow rate is less than the water flow rate threshold, perform the following steps.

[0056] Step S3: Detect the water flow temperature. If the water flow temperature does not reach the preset temperature threshold, continue to perform cyclic heating. When the water flow temperature reaches the preset temperature threshold, calculate the current water flow frequency and control the working state of cyclic heating according to the current water flow frequency.

[0057] For example, a method for detecting water flow temperature can be as follows: a water temperature detection unit for measuring water flow temperature is installed in the hot water pipeline. The water temperature detection unit can be a thermocouple, a thermistor, or a water temperature sensor, etc. The water temperature detection unit is then connected to the main controller, and the main controller reads the water flow temperature data measured by the water temperature detection unit in real time.

[0058] On the other hand, in this embodiment, when the current water flow is less than the water flow threshold, another implementation of step S3 can be: periodically detecting the water flow temperature, continuing to perform cyclic heating when the water flow temperature does not reach the preset temperature threshold, and calculating the current water flow frequency when the water flow temperature reaches the preset temperature threshold, and controlling the working state of cyclic heating according to the current water flow frequency.

[0059] For example, a method for periodically detecting water flow temperature can be as follows: a water temperature detection unit for measuring water flow temperature is installed in the hot water pipeline. The water temperature detection unit can be a thermocouple, a thermistor, or a water temperature sensor, etc. The water temperature detection unit is then connected to the main controller. Subsequently, a detection cycle is set in the main controller. When each detection cycle arrives, the main controller reads the water flow temperature data measured by the water temperature detection unit.

[0060] Among them, the shape memory alloy check valve is a type of check valve with a shape memory effect. Besides preventing cold water from flowing back into hot water pipes, the shape memory alloy check valve can also quickly change its valve opening according to changes in water temperature. It exhibits good elasticity and recovery performance within a certain temperature range, and the valve opening determines the flow rate through the shape memory alloy check valve. Therefore, by using this shape memory alloy check valve, the flow rate in the pipeline can quickly respond to changes in water temperature, and the unidirectional flow of water in the pipeline can be accurately controlled.

[0061] By determining the water flow threshold based on the historical water flow during the operation of the gas water heater, and controlling the working state of the water heater's circulating heating from multiple dimensions, compared with the existing gas water heating system's continuous circulating heating scheme, this method reduces the number of times the gas water heater operates in the internal circulation state while ensuring the water temperature in the hot water pipes, thus significantly reducing gas consumption. Simultaneously, by detecting the water flow temperature, the opening of the shape memory alloy check valve 6 is affected, thus influencing the flow frequency within the gas-fired water heating system pipeline. Based on this change in flow frequency, the circulating heating operation is controlled. After the water in the gas-fired water heating system has heated the entire hot water pipeline and passed through the shape memory alloy check valve 6, the valve opening rapidly decreases, resulting in a sharp drop in flow. This change in flow frequency allows the circulating heating of the gas-fired water heating system to stop. This ensures that the end of the shape memory alloy check valve 6 facing the hot water pipeline is hot water, while the end facing the cold water pipeline is cold water. This significantly reduces the amount of hot water flowing from the hot water pipeline 2 into the cold water pipeline 3, thereby reducing the impact of the circulating heating system on the water purifier within the cold water pipeline 3.

[0062] On the other hand, in this embodiment, the shape memory alloy check valve 6 uses a shape memory alloy spring 7 as the valve sealing drive component. Please refer to the attached document. Figure 2 The methods for obtaining the preset temperature threshold include:

[0063] Step A01: Obtain the maximum elastic force of the shape memory alloy spring 7 and the minimum compression of the shape memory alloy spring 7 when the valve opening is at its minimum.

[0064] Step A02: Divide the maximum elastic force by the minimum compression to obtain the maximum elastic force coefficient of the shape memory alloy spring 7;

[0065] Step A03: Based on the properties of the selected memory alloy spring 7, select a temperature threshold that matches the maximum elastic coefficient of the memory alloy spring 7.

[0066] The working principle of the one-way valve in a water heater, which uses a shape memory alloy spring 7 as the valve-closing actuator, is as follows: When water flows through the one-way valve, the pressure of the water flow acts on the shape memory alloy spring 7, compressing it and increasing the opening of the one-way valve, allowing water to flow normally through the valve. When the water flow stops, the shape memory alloy spring 7 automatically expands back, reducing the opening of the one-way valve until the valve closes, preventing hot water backflow. Meanwhile, during the circulating heating process of the water heater, the temperature of the hot water will rise, and the elastic coefficient of the shape memory alloy spring 7 will also increase accordingly. This makes the one-way valve have a better sealing ability for hot water at higher temperatures, allowing the valve drive to automatically close at high temperatures. This causes a sharp decrease in the flow rate in the cold water pipe, resulting in a significant reduction in the flow rate frequency. Based on the current flow rate frequency, the gas water heating system is controlled to stop circulating heating, ensuring that the end of the shape memory alloy one-way valve 6 facing the hot water pipe is hot water and the end of the shape memory alloy one-way valve 6 facing the cold water pipe 3 is cold water. This significantly reduces the amount of hot water flowing from the hot water pipe into the cold water pipe, thereby reducing the impact of the circulating heating system on the water purifier in the cold water pipe.

[0067] By using shape memory alloy springs as valve-closing actuators, and leveraging the relationship between the spring force coefficient of the shape memory alloy spring and temperature, adaptive control of the shape memory alloy check valve can be achieved at different temperatures, making the circulating heating of the gas-fired hot water system more efficient.

[0068] For the relationship between the spring force coefficient of shape memory alloy spring 7 and the water temperature, please refer to the appendix. Figure 3 Therefore, based on the relationship between the elastic coefficient of the shape memory alloy spring 7 and the temperature, the temperature that matches the maximum elastic coefficient of the shape memory alloy spring 7 can be selected as the temperature threshold, thereby realizing the adaptive control of the shape memory alloy one-way valve 6 at different temperatures, making the circulating heating of the gas water heater more efficient. This also makes the circulating heating process of the water heater more stable and reliable, avoiding problems such as hot water backflow or water flow backflow caused by mismatch in spring elastic coefficient.

[0069] In a check valve, the valve opening degree refers to the extent to which the valve is open or the size of the valve opening during operation. The size of the valve opening degree determines the flow rate through the check valve and also affects the flow frequency. Generally speaking, a larger valve opening degree results in a larger flow rate and a higher flow frequency; conversely, a smaller valve opening degree results in a smaller flow rate and a lower flow frequency.

[0070] Therefore, when the water temperature increases, the spring force coefficient increases, which reduces the opening of the shape memory alloy check valve 6, thus decreasing the water flow rate in the pipeline. Please refer to the appendix for the relationship between water temperature and water flow rate. Figure 4 For the operating status of the shape memory alloy check valve 6 under different water flow temperatures and flow rates, please refer to the appendix. Figure 5 .

[0071] On the other hand, in this embodiment, the method for obtaining the maximum elastic force of the shape memory alloy spring 7 includes:

[0072] The pressure in the water heater pipes is monitored in real time after the water pump starts, and recorded as F. 压 Then F at the maximum valve opening 压 This is the maximum elastic force of the shape memory alloy spring 7.

[0073] In this embodiment, by converting the measurement of spring force into the measurement of pressure within the pipeline, the maximum spring force of the shape memory alloy spring 7 can be directly obtained without the need for separate force measurement of the spring, which is convenient and quick. Furthermore, converting the measurement of spring force into the measurement of pressure within the pipeline allows for the use of high-precision measuring equipment such as pressure sensors, improving measurement accuracy. Simultaneously, in gas water heaters, real-time detection of pressure within the pipeline to provide feedback on spring force offers a more intuitive reflection of the equipment's operating status, aiding in fault diagnosis and maintenance.

[0074] On the other hand, in this embodiment, the method for calculating the current flow rate frequency in step S3 includes:

[0075] Obtain the water flow rate at each moment during the operation of the gas water heater;

[0076] The average water flow rate during the current time period during the operation of the gas water heater is determined based on the water flow rate at each moment during the operation of the gas water heater.

[0077] Calculate the current flow rate frequency based on the average flow rate.

[0078] The water flow rate at each moment during the operation of the gas water heater is measured and obtained by the water flow detection unit 1.

[0079] On the other hand, in this embodiment, the current flow rate frequency is specifically calculated using the following formula:

[0080] F = 8.1 × Q - 3

[0081] Where F represents the current water flow frequency, and Q represents the average water flow during the current time period while the gas water heater is running.

[0082] On the other hand, in this embodiment, step S3, the method for controlling the working state of the circulating heating according to the current water flow frequency includes:

[0083] If the current water flow frequency is greater than or equal to the preset frequency threshold, the cycle heating will continue; if the current water flow frequency is less than the preset frequency threshold, the cycle heating will stop.

[0084] By controlling the circulating heating operation of a gas water heater based on the current water flow frequency, gas consumption can be effectively saved, thereby reducing energy efficiency. Compared to controlling solely based on water flow, this method better avoids fluctuations in hot water temperature caused by flow fluctuations. Furthermore, it intelligently adjusts the circulating heating operation of the gas water heater according to actual needs during use, adapting to different flow conditions, improving the system's adaptability, reducing the number of times the water heater cycles through heating, lowering the frequency of use, and ultimately extending the water heater's lifespan.

[0085] In summary, please refer to the attached flowchart for the working state of the gas water heater's circulating heating process. Figure 6 .

[0086] On the other hand, in this embodiment, the method for determining the water flow threshold based on the water flow during the historical operation of the gas water heater in step S1 includes:

[0087] Obtain the water flow rate at each moment during the historical operation of the gas water heater;

[0088] The average flow rate over multiple time periods during the historical operation is determined based on the water flow rate at each moment during the historical operation.

[0089] The flow rate threshold is calculated based on the average flow rate over multiple time periods.

[0090] On the other hand, in this embodiment, the method for calculating the flow rate threshold based on the average flow rate over multiple time periods includes:

[0091] The minimum value among the average flow rates over multiple time periods is selected, and the minimum value is multiplied by a preset coefficient to obtain the flow rate threshold.

[0092] For example, the method for determining the water flow threshold based on the water flow during the historical operation of the gas water heater is as follows:

[0093] First, we need to obtain the flow rate data for each moment in the historical operation. Let's assume we obtain flow rate data for five moments: 2.5, 3.0, 3.5, 2.8, and 2.3. Next, we divide these five moments into three time periods in chronological order and calculate the average flow rate (in L / min) for each period: 2.75, 3.15, and 2.55. Then, we select the minimum value from these three average flow rates, which is 2.55 L / min. Finally, we multiply this minimum value by a preset coefficient of 1.17 to obtain a flow rate threshold of 3 L / min.

[0094] Example 2:

[0095] This application also provides a gas-fired hot water system for implementing the aforementioned control method for a gas-fired hot water system. Please refer to the appendix. Figure 7 ,include:

[0096] A gas water heater, comprising a water pump assembly 4, a water flow detection unit 1, a water temperature detection unit, and a main controller 5. The water pump assembly 4 is used to provide power for the circulating heating of the gas water heater. The water flow detection unit 1 is used to obtain the water flow rate at each moment during the operation of the gas water heating system. The water temperature detection unit is used to detect the water flow temperature. The water pump assembly 4, the water flow detection unit 1, and the water temperature detection unit are all electrically connected to the main controller 5.

[0097] Hot water pipe 2 and cold water pipe 3, wherein the hot water pipe 2 is connected to the outlet of the gas water heater and the cold water pipe 3 is connected to the inlet of the gas water heater;

[0098] A shape memory alloy check valve 6 is connected between the hot water pipe 2 and the cold water pipe 3 to form a circulating water circuit;

[0099] The shape memory alloy one-way valve 6 uses a shape memory alloy spring 7 as the valve sealing drive component.

[0100] Among them, the shape memory alloy check valve 6 is a type of check valve with shape memory effect. Besides preventing cold water from flowing back into the hot water pipe, the shape memory alloy check valve 6 can also quickly change its valve opening according to changes in water temperature. It has good elasticity and recovery performance within a certain temperature range, and the valve opening determines the flow rate through the shape memory alloy check valve 6. Therefore, by using this shape memory alloy check valve 6, the flow rate in the pipeline can quickly respond to changes in water temperature, and the unidirectional flow of water in the pipeline can be accurately controlled.

[0101] The water volume detection unit 1 can be a water volume sensor, flow meter, pressure sensor or liquid level sensor, etc., and the water temperature detection unit can be a thermocouple, thermistor, water temperature sensor, etc. This embodiment does not limit the specific type of water volume detection unit.

[0102] Among them, the water pump assembly 4 → C → D is the hot water pipe 2, the A → E is the cold water pipe 3, and the A → B → C → D → shape memory alloy check valve 6 → E → A → B is the circulating water circuit.

[0103] On the other hand, in this embodiment, a pressure detection unit is provided on the hot water pipe 2, which is used to detect the pressure in the gas hot water system pipe.

[0104] The pressure detection unit can be a pressure sensor, pressure transmitter, differential pressure sensor, or level gauge, etc., and this embodiment does not limit it.

[0105] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Those skilled in the art should understand that the present invention includes, but is not limited to, the contents described in the accompanying drawings and the specific embodiments above. Any modifications that do not depart from the functional and structural principles of the present invention will be included within the scope of the claims.

Claims

1. A control method for a gas-fired hot water system, characterized in that, Control of a gas-fired hot water system employing a shape memory alloy check valve includes the following steps: Step S1: Determine the flow rate threshold based on the flow rate during the historical operation of the gas-fired hot water system; Step S2: Obtain the current water flow rate of the gas-fired hot water system. When the current water flow rate is greater than or equal to the water flow rate threshold, perform cyclic heating. When the current water flow rate is less than the water flow rate threshold, perform the following steps: Step S3: Detect the water flow temperature. If the water flow temperature does not reach the preset temperature threshold, continue to perform cyclic heating. If the water flow temperature reaches the preset temperature threshold, calculate the current water flow frequency. If the current water flow frequency is greater than or equal to the preset frequency threshold, continue to perform cyclic heating. If the current water flow frequency is less than the preset frequency threshold, stop performing cyclic heating. The methods for calculating the current flow frequency include: Obtain the water flow rate at each moment during the operation of the gas-fired hot water system; The average water flow Q during the current time period of the gas-fired hot water system is determined based on the water flow rate at each moment during the operation of the gas-fired hot water system. Calculate the current flow frequency F based on the average flow rate Q: .

2. The control method for a gas-fired hot water system as described in claim 1, characterized in that, The shape memory alloy check valve uses a shape memory alloy spring as the valve sealing actuator, and the method for obtaining the preset temperature threshold includes: Obtain the maximum elastic force of the shape memory alloy spring and the minimum compression of the shape memory alloy spring when the valve opening is minimum; Divide the maximum elastic force by the minimum compression to obtain the maximum elastic force coefficient of the memory alloy spring; Based on the properties of the selected memory alloy spring, a temperature threshold is selected that matches the maximum elastic coefficient of the memory alloy spring.

3. The control method for a gas-fired hot water system as described in claim 2, characterized in that, The method for obtaining the maximum elastic force of the shape memory alloy spring includes: Real-time monitoring of the pressure in the hot water system pipes after the water pump starts, recorded as follows: Then at the maximum valve opening This is the maximum elastic force of the memory alloy spring.

4. A control method for a gas-fired hot water system as described in any one of claims 1 to 3, characterized in that, In step S1, the method for determining the flow rate threshold based on the flow rate during the historical operation of the gas-fired hot water system includes: Obtain the water flow rate at each moment during the historical operation of the gas-fired hot water system; The average flow rate over multiple time periods during the historical operation is determined based on the water flow rate at each moment during the historical operation. The flow rate threshold is calculated based on the average flow rate over the multiple time periods.

5. The control method for a gas-fired hot water system as described in claim 4, characterized in that, The method for calculating the flow rate threshold based on the average flow rate over the multiple time periods includes: The minimum value among the average flow rates of the multiple time periods is selected, and the minimum value is multiplied by a preset coefficient ratio to obtain the flow rate threshold.

6. A gas-fired hot water system, used to execute the control method for a gas-fired hot water system as described in claims 1 to 5, characterized in that, include: A gas water heater, comprising a water pump assembly, a water flow detection unit, a water temperature detection unit, and a main controller, wherein the water pump assembly provides power for the circulating heating of the gas water heater, the water flow detection unit acquires the water flow rate at each moment during the operation of the gas water heating system, and the water temperature detection unit detects the water flow temperature; the water pump assembly, the water flow detection unit, and the water temperature detection unit are all electrically connected to the main controller. Hot water pipe and cold water pipe, wherein the hot water pipe is connected to the outlet of the gas water heater and the cold water pipe is connected to the inlet of the gas water heater; A shape memory alloy check valve connects the hot water pipe and the cold water pipe to form a circulating water circuit; The shape memory alloy check valve uses a shape memory alloy spring as the valve sealing drive component.

7. A gas-fired hot water system as described in claim 6, characterized in that, The hot water pipe is equipped with a pressure detection unit, which is used to detect the pressure in the gas-fired hot water system pipe.

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