Temperature control method and system for gas water heater

Abstract

The invention provides a temperature control method and system for a gas water heater, and when a large thermal load adjustment event is detected, the temperature control process comprises the following steps: in a water temperature lag response stage, outputting according to an increased thermal load value; wherein the duration of the water temperature lag response stage is dynamically determined according to the current water flow; in a normal thermal load output stage, outputting according to a normal thermal load value smaller than or equal to the increased thermal load value; and in the automatic constant-temperature modulation stage, the water outlet temperature is kept stable through a PID control algorithm. According to the temperature control method and system for the gas water heater, the outlet water temperature can more quickly approach the set value, the time for the outlet water temperature to approach the set value is shortened, and the response speed for the outlet water temperature to approach the set value is increased. And then the normal heat load value is switched for heating, and the output target value is stabilized, so that the water outlet temperature can rapidly reach the set temperature, and the water temperature fluctuation is small in the using process. And in the automatic constant-temperature modulation stage, the water outlet temperature is kept stable through a PID control algorithm.

Description

Technical Field

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

[0002] Gas water heaters are common household appliances. They use gas as fuel and control the amount of heat required to supply water by regulating the flow of gas into the heater. A typical gas water heater consists of a casing, a burner, and a heat exchanger housed within the casing. Inlet and outlet pipes on the casing connect to the heat exchanger. Cold water entering through the inlet pipe is heated by the heat exchanger and then hot water is output through the outlet pipe.

[0003] With the development of smart products and the improvement of users' living standards, gas water heaters with automatic thermostats are becoming increasingly common, and although they all meet national standards, superior temperature control can enhance the user's water experience. An inappropriate temperature setting on a gas water heater can cause significant inconvenience, such as when showering. Especially during water outages or fluctuations in water flow, ensuring the water temperature quickly reaches the set temperature is a problem that urgently needs to be solved. Summary of the Invention

[0004] This invention provides a method and system for temperature control of a gas water heater, enabling the outlet water temperature to approach the set value more quickly, reducing the time required to reach the set value, and accelerating the response speed. Then, it switches to the normal heat load value for heating, stabilizing the output target value, so that the outlet water temperature can quickly reach the set temperature with minimal temperature fluctuations during use. During the automatic thermostatic modulation stage, a PID control algorithm maintains a stable outlet water temperature.

[0005] In a first aspect, embodiments of the present invention provide a method for temperature control of a gas water heater, wherein when a large heat load adjustment event is detected, the temperature control process includes:

[0006] During the water temperature lag response phase, the output is increased according to the heat load value; the duration of the water temperature lag response phase is dynamically determined based on the current water flow rate.

[0007] During the normal heat load output phase, the output should be less than or equal to the normal heat load value of the increased heat load value;

[0008] During the automatic thermostatic modulation stage, the PID control algorithm is used to maintain a stable outlet water temperature.

[0009] Optionally, the duration of the water temperature hysteresis response phase is , hour:

[0010] ;

[0011] in, The preset maximum duration threshold, The preset minimum length threshold, The preset maximum water flow threshold, The preset minimum water flow threshold, This represents the current water flow rate.

[0012] hour, ; hour, .

[0013] Optionally, the duration of the water temperature hysteresis response phase can be dynamically corrected through self-learning.

[0014] Optionally, outputting an increased heat load value includes:

[0015] Based on the change in heat load The overshoot ratio coefficient can be determined by looking up a table or the first relation. Alternatively, the overshoot ratio can be determined based on the temperature change. Alternatively, the overshoot ratio coefficient can be determined based on the change in water flow. ; ;

[0016] according to Determine the value of increasing the heat load. ;in, This is the original heat load value before the large heat load adjustment event.

[0017] Optionally, the first relation is in When satisfied:

[0018] ;

[0019] in, The preset maximum heat load change threshold, This is the preset minimum heat load change threshold.

[0020] Optionally, the duration of the normal heat load output phase is dynamically determined based on the current water flow rate.

[0021] Optionally, the output may be a normal heat load value that is less than or equal to the increased heat load value, including:

[0022] according to Determine the normal heating load value ,in, The original heat load value before the large heat load adjustment event. This represents the change in heat load.

[0023] Optionally, a large heat load adjustment event includes at least one of the following: gas water heater starting combustion, sudden change in water flow, and change in set temperature.

[0024] Secondly, embodiments of the present invention provide a gas water heater temperature control system, including a gas water heater;

[0025] Processing equipment, which is connected to the gas water heater;

[0026] The processing device includes: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the temperature control method as described in the first aspect.

[0027] In this embodiment of the invention, when a large heat load adjustment event is detected, temperature control is implemented in stages. During the water temperature lag response stage, the output is based on an increased heat load value. During the normal heat load output stage, the output is based on the normal heat load value. Because an overshoot of a value greater than or equal to the normal heat load value is actively used during the water temperature lag response stage to counteract the system's thermal inertia lag, this deliberate, temporary overheating, using an extra heat load initially, allows the outlet water temperature to approach the set value more quickly, reducing the time required to reach the set value and accelerating the response speed. Afterwards, the system switches to the normal heat load value for heating, stabilizing the output target value, ensuring the outlet water temperature quickly reaches the set temperature with minimal fluctuations during use. Following the normal heat load output stage, an automatic constant temperature modulation stage is also included. During the automatic constant temperature modulation stage, a PID control algorithm maintains stable outlet water temperature. A strategy of first overshooting and then converging is employed to achieve rapid attainment of the set temperature with minimal fluctuations. Attached Figure Description

[0028] Figure 1 A flowchart of another gas water heater temperature control method provided in an embodiment of the present invention;

[0029] Figure 2 A flowchart of another gas water heater temperature control method provided in an embodiment of the present invention;

[0030] Figure 3 A graph showing the change in water flow rate;

[0031] Figure 4 To set up a temperature change curve;

[0032] Figure 5 This is a graph showing the start-up curve of boiling water.

[0033] Figure 6 This is a schematic diagram of a processing device structure provided in an embodiment of the present invention. Detailed Implementation

[0034] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0035] Figure 1 A flowchart of a gas water heater temperature control method provided in an embodiment of the present invention; see reference. Figure 1 When a large heat load adjustment event is detected, the temperature control process includes:

[0036] S101. During the water temperature lag response stage, output according to the increased heat load value.

[0037] The high heat load adjustment events include at least one of the following: gas water heater start-up, sudden change in water flow, and change in set temperature. When the user turns on the tap and controls the flow of hot water, the gas water heater starts combustion. This event will be referred to as "hot water start-up" below. A sudden change in water flow occurs when the user increases or decreases the hot water flow from the tap. A change in set temperature allows the user to adjust the set temperature higher or lower, for example, changing the set temperature from 40℃ to 43℃.

[0038] The lag time varies depending on the water flow rate; a smaller flow rate results in a longer lag time, and vice versa. Therefore, the duration of the water temperature lag response phase is dynamically determined based on the current water flow rate. By controlling the duration of the water temperature lag response phase, the duration of overshoot output is controlled, avoiding negative effects of overshoot, such as excessive overshoot leading to excessively high or low outlet water temperatures.

[0039] S102. During the normal heat load output phase, output the normal heat load value, which is less than or equal to the increased heat load value.

[0040] The normal heat load value refers to the theoretically precise heat power output required for a gas water heater to heat the water flow from the inlet temperature to the set temperature.

[0041] S103. During the automatic constant temperature modulation stage, the outlet water temperature is maintained stable through the PID control algorithm.

[0042] PID stands for Proportional-Integral-Derivative, a classic feedback control algorithm that has been used in industrial control for over a century. Its core idea is to measure the error between the system's actual output and the desired target, and based on the current value, historical cumulative value, and trend of the error, calculate a precise control quantity to stabilize the system output near the target value.

[0043] In this embodiment of the invention, when a large heat load adjustment event is detected, temperature control is implemented in stages. During the water temperature lag response stage, the output is based on an increased heat load value. During the normal heat load output stage, the output is based on the normal heat load value. Because an overshoot of a value greater than or equal to the normal heat load value is actively used during the water temperature lag response stage to counteract the system's thermal inertia lag, more heat is output within the lag time, allowing the outlet water temperature to approach the set value more quickly. Then, the system switches to the normal heat load value for heating, ensuring the outlet water temperature quickly reaches the set temperature with minimal fluctuations during use. Following the normal heat load output stage, an automatic constant temperature modulation stage is also included. During the automatic constant temperature modulation stage, a PID control algorithm maintains stable outlet water temperature. A strategy of first overshooting and then converging is employed to achieve rapid attainment of the set temperature with minimal fluctuations.

[0044] In this invention, the PID control algorithm drives the combustion system of the gas water heater according to the control signal, enabling the outlet water temperature to accurately track the set temperature. A problem with traditional methods using only the PID control algorithm is that a gas water heater is a physical system with significant thermal inertia and transmission lag. For example, when starting up from cold water to 40°C, a large initial error occurs, causing the PID to output rapidly. However, heat transfer to the outlet water takes time, resulting in lag. When the water temperature begins to rise, the PID (especially the integral term I) has already output far more heat than actually needed, causing the outlet water temperature to exceed the set temperature and triggering continuous oscillations. In this embodiment, the PID control algorithm, after the aforementioned steps S101 and S102, further serves as a precise fine-tuning step, building upon the previous coarse and rapid adjustments.

[0045] The PID control algorithm is a closed-loop feedback system. It continuously monitors the outlet water temperature and compares it with the set temperature, constantly adjusting its actions based on the deviation. The P, I, and D terms in the PID control algorithm work together to generate a dynamic control force from three dimensions: current deviation, historical accumulation, and future trend. This force continuously drives the gas water heater's combustion system towards the target point and can counteract the effects of various internal and external disturbances in real time.

[0046] Optionally, the duration of the water temperature hysteresis response phase is , hour:

[0047] ;

[0048] in, The preset maximum duration threshold, The preset minimum length threshold, The preset maximum water flow threshold, The preset minimum water flow threshold, This represents the current water flow rate.

[0049] Furthermore, The duration of the water temperature hysteresis response phase equal . The duration of the water temperature hysteresis response phase equal . , , and The value depends on the product's debugging parameters.

[0050] Optionally, the duration of the water temperature lag response phase can be dynamically corrected through self-learning. The above formula provides theoretical initial values ​​based on an ideal model, while self-learning addresses the complex and variable actual correction values ​​in the real world. Due to differences in product usage scenarios, It can automatically correct itself during use. Differences in usage scenarios are reflected in individual product deviations, installation environment (such as water line length and number of bends), and local water quality. Differences in usage scenarios are also reflected in the performance drift of gas water heaters during use, and the longer the usage time, the greater the performance drift.

[0051] When a large heat load adjustment event is detected, the self-learning process is triggered. Recording begins at time [number]. Recording ends when the outlet water temperature rises or falls above a threshold (e.g., 1°C). The interval between the start and end of recording is the duration of the actual measured water temperature lag response phase under this event. Outlet water temperature is recorded periodically (e.g., every 100ms), continuously recording temperature data for 5 seconds. During this 5-second period, if the recorded temperature fluctuation is less than a set threshold (e.g., 0.2°C), it is defined as the temperature stabilization period. This ensures the heating process is successful and stable, eliminating invalid data caused by external interference (e.g., sudden water shut-off).

[0052] Once the stabilization period conditions are met, the self-learning process takes effect. The duration of the water temperature hysteresis response phase learned in this study is compared with the current water flow rate. Connect the values ​​and update the internal Q-t1 mapping table. The update strategy could be to overwrite the old values ​​with the new ones, or to use a weighted average.

[0053] Figure 2 A flowchart of another gas water heater temperature control method provided in an embodiment of the present invention; see reference. Figure 2 When a large heat load adjustment event is detected, the temperature control process includes:

[0054] S201. During the water temperature hysteresis response phase, based on the change in heat load... The overshoot ratio coefficient can be determined by looking up a table or the first relation. .

[0055] in, Changes in heat load This refers to the difference in heat load required to respond to changes in system state. To quickly adjust the outlet water temperature to the set temperature, an increase in output heat load is needed during the water temperature lag response phase; if it's a gas water heater starting combustion, the required change in output heat load needs to be calculated. ;in, To set the temperature, This refers to the inlet water temperature of the gas water heater. It can be a positive or negative value. If the set temperature changes, the change in the set temperature difference is... , This represents the change in required heat load calculated by subtracting the original set temperature from the new set temperature. ; It can be a positive or negative value. If there is a sudden change in water flow... This represents the change in water flow rate (current flow rate minus original flow rate). It is used to calculate the required change in heat load. . It can be a positive or negative value.

[0056] Based on the change in heat load To determine the overshoot ratio coefficient This allows for the determination of the overshoot heat load. Adjustments are made based on the principle of small adjustments for small loads and large adjustments for large loads; the greater the change in heat load, the greater the deviation, requiring a rapid increase in temperature rise or a stabilization temperature, and thus the overshoot proportional coefficient. The larger the value, the faster the overshoot can be determined using a lookup table.

[0057]

[0058] In the table, The preset minimum heat load change threshold, The preset maximum heat load change threshold, . hour, . hour, .

[0059] Optionally, the first relation is in When satisfied:

[0060] ;

[0061] in, The preset maximum heat load change threshold, This is the preset minimum heat load change threshold. hour, ; hour, .

[0062] S202, according to Determine the value of increasing the heat load. .

[0063] in, This refers to the original heat load value prior to the large heat load adjustment event. For example, hour, Increase heat load value satisfy: . A value greater than or equal to 1 indicates an overshoot of the heat load.

[0064] S203. During the normal heat load output phase, according to Determine the normal heating load value .

[0065] in, The original heat load value before the large heat load adjustment event. This represents the change in heat load. The duration of the normal heat load output phase is dynamically determined based on the current water flow rate.

[0066] Optionally, the duration of the normal heat load output phase is , hour:

[0067] ;

[0068] in, The preset maximum duration threshold, The preset minimum length threshold, The preset maximum water flow threshold, The preset minimum water flow threshold, This represents the current water flow rate.

[0069] Furthermore, hour, equal . hour, equal . , , and The value depends on the product's debugging parameters.

[0070] S204. During the automatic constant temperature modulation stage, the PID control algorithm is used to maintain a stable outlet water temperature.

[0071] There are several alternatives to step S301 described above. In one alternative, the overshoot ratio is determined based on the temperature change. For example, if the overshoot temperature is below 3 degrees, the overshoot ratio is 1; if the temperature change is between 3 and 10 degrees, the overshoot ratio is... The overshoot ratio is 1.3; the temperature change is between 10-20 degrees Celsius. The overshoot ratio is 1.5; when the temperature change is greater than 20 degrees, the overshoot ratio is... It is version 2.0.

[0072] In another alternative, the overshoot ratio is determined based on the change in water flow. For example, if the water flow rate change is less than 2 L / min, the overshoot ratio factor... =1; water flow rate variation 2-3L / MIN, overshoot ratio coefficient The overshoot ratio is 1.3; the water flow rate variation is 3-4 L / min. The overshoot ratio is 1.5; when the water flow rate change is greater than 4 L / min, the overshoot ratio is 1.5. It is version 2.0.

[0073] Figure 3 This is a graph showing the change in water flow. Figure 4 To set up a temperature change curve, Figure 5 For the boiling water start-up curve, please refer to... Figures 3-5 The horizontal axis represents time, and the vertical axis plots the changes in set temperature, outlet water temperature, heat load, and water flow rate. At time 0, a large heat load adjustment event is detected. Time 0 to time t11 represents the duration of the water temperature hysteresis response phase. Due to the thermal inertia of the gas water heater heating system, it takes time for water to pass through the heat exchanger, and there is also a delay in the temperature sensor detecting temperature changes. At time 0, although the output is based on the increased heat load value, the change in outlet water temperature is delayed until after time 0. Time t11 to time t12 represents the duration of the normal heat load output phase. The period following time t12 is the automatic isotropic modulation phase. Figures 3-5 It is evident that the outlet water temperature can quickly reach the set temperature and the water temperature fluctuates little during use.

[0074] Figure 6 This is a schematic diagram of a processing device structure provided in an embodiment of the present invention, with reference to... Figure 6This invention provides a temperature control system for a gas water heater. The system includes a gas water heater and a processing device 50 connected to the gas water heater. The processing device 50 includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, it implements the temperature control method described in the first aspect. Therefore, it has the beneficial effects of the corresponding temperature control method. Similarities can be found in the above description, which will not be repeated here.

[0075] The processing device 50 is intended to represent various forms of digital computers, such as laptop computers, desktop computers, workstations, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. The processing device 50 may also represent various forms of mobile devices, such as personal digital processors, cellular phones, smartphones, wearable devices (such as helmets, glasses, watches, etc.), and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely illustrative and are not intended to limit the implementation of the invention described and / or claimed herein.

[0076] like Figure 6 As shown, the processing device 50 includes at least one processor 51 and a memory, such as a read-only memory (ROM) 52 and a random access memory (RAM) 53, communicatively connected to the at least one processor 51. The memory stores computer programs executable by the at least one processor. The processor 51 can perform various appropriate actions and processes based on the computer program stored in the ROM 52 or loaded from storage unit 58 into the RAM 53. The RAM 53 may also store various programs and data required for the operation of the processing device 50. The processor 51, ROM 52, and RAM 53 are interconnected via a bus 54. An input / output (I / O) interface 55 is also connected to the bus 54.

[0077] Multiple components in the processing device 50 are connected to the I / O interface 55, including: an input unit 56, such as a keyboard, mouse, etc.; an output unit 57, such as various types of displays, speakers, etc.; a storage unit 58, such as a disk, optical disk, etc.; and a communication unit 59, such as a network card, modem, wireless transceiver, etc. The communication unit 59 allows the processing device 50 to exchange information / data with other devices through computer networks such as the Internet and / or various telecommunications networks.

[0078] Processor 51 can be a variety of general-purpose and / or special-purpose processing components with processing and computing capabilities. Some examples of processor 51 include, but are not limited to, a central processing unit (CPU), a graphics processing unit (GPU), various special-purpose artificial intelligence (AI) computing chips, various processors running machine learning model algorithms, a digital signal processor (DSP), and any suitable processor, controller, microcontroller, etc. Processor 51 performs the various methods and processes described above, such as those applied to temperature control methods.

[0079] Note that the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, combinations, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention, the scope of which is determined by the scope of the appended claims.

Claims

1. A method for temperature control in a gas water heater, characterized in that, When a large heat load adjustment event is detected, the temperature control process includes: During the water temperature lag response phase, the output is increased according to the heat load value; wherein, the duration of the water temperature lag response phase is dynamically determined according to the current water flow rate. During the normal heat load output phase, the output is based on a normal heat load value that is less than or equal to the increased heat load value. During the automatic thermostatic modulation stage, the PID control algorithm is used to maintain a stable outlet water temperature.

2. The gas water heater temperature control method according to claim 1, characterized in that, The duration of the water temperature hysteresis response phase is , hour: ； in, The preset maximum duration threshold, The preset minimum length threshold, The preset maximum water flow threshold, The preset minimum water flow threshold, This represents the current water flow rate.

3. The gas water heater temperature control method according to claim 2, characterized in that, hour, ; hour, .

4. The gas water heater temperature control method according to claim 1, characterized in that, The duration of the water temperature hysteresis response phase is dynamically corrected through self-learning.

5. The gas water heater temperature control method according to claim 1, characterized in that, According to the increased heat load value output, including: Based on the change in heat load The overshoot ratio coefficient can be determined by looking up a table or the first relation. Alternatively, the overshoot ratio can be determined based on the temperature change. Alternatively, the overshoot ratio coefficient can be determined based on the change in water flow. ; ; according to Determine the increased heat load value ;in, This is the original heat load value before the large heat load adjustment event.

6. The gas water heater temperature control method according to claim 5, characterized in that, The first relation is in When satisfied: ； in, The preset maximum heat load change threshold, This is the preset minimum heat load change threshold.

7. The gas water heater temperature control method according to claim 1, characterized in that, The duration of the normal heat load output phase is dynamically determined based on the current water flow rate.

8. The gas water heater temperature control method according to claim 1, characterized in that, Output a normal heat load value that is less than or equal to the increased heat load value, including: according to Determine the normal heating load value ,in, The original heat load value before the large heat load adjustment event. This represents the change in heat load.

9. The gas water heater temperature control method according to claim 1, characterized in that, The high heat load adjustment event includes at least one of the following: the gas water heater starts combustion, water flow changes suddenly, and the set temperature changes.

10. A temperature control system for a gas water heater, characterized in that, Including gas water heaters; A processing device, wherein the processing device is connected to the gas water heater; The processing device includes: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the temperature control method as described in any one of claims 1-9.

Images