Water tank water temperature control method, control system of heat pump system and heat pump system

Abstract

The invention discloses a water tank water temperature control method, a heat pump system control system and a heat pump system.The water tank is arranged in the heat pump system, and the water tank water temperature control method comprises the steps that the water inlet temperature and the water outlet temperature of the water tank are monitored; determining whether the user is in a water use stage or not and whether the water tank is in a water production stage or not according to at least one of the decline rate of the inlet water temperature and the decline rate of the outlet water temperature; determining a water temperature interval to which the outlet water temperature belongs according to a relative relation between the outlet water temperature of the water tank and a set temperature; and when it is determined that the user is in the water using stage or the water tank is in the water producing stage, whether a hot water pump in the heat pump system is controlled to be started or not is determined according to at least one of the water temperature interval and the hot water pump starting condition. Whether the user is in the water using stage or not can be determined, so that starting and stopping of the hot water pump are controlled, the hot water yield of the water tank can be maximized, meanwhile, water outlet temperature fluctuation caused by water mixing of the water tank is reduced, and the user experience is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of heat pumps, and in particular to a method for controlling water temperature of a water tank, a control system of a heat pump system, and a heat pump system. Background Art

[0002] Conventional circulating hot water tanks determine the start and stop of hot water based on the water inlet temperature of the water tank, and cannot accurately determine whether the user is using water. If the user is using water, the hot water starts, and the hot water pump is running, the cold and hot water mixing area in the water tank will become larger, causing the water outlet temperature of the water tank to fluctuate greatly, affecting the user experience. Summary of the invention

[0003] The present invention provides a method for controlling water temperature in a water tank, a control system of a heat pump system and a heat pump system, which can determine whether a user is in the water use stage, thereby controlling the start and stop of a hot water pump, and can maximize the hot water output of the water tank, while reducing the fluctuation of the water outlet temperature caused by water mixing in the water tank, thereby improving the user experience.

[0004] In a first aspect, an embodiment of the present invention provides a method for controlling water temperature of a water tank, wherein the water tank is arranged in a heat pump system, and the method for controlling water temperature of the water tank comprises: monitoring the inlet water temperature and the outlet water temperature of the water tank; determining whether a user is in a water use stage and determining whether the water tank is in a water production stage according to at least one of the decreasing rate of the inlet water temperature and the decreasing rate of the outlet water temperature; determining a water temperature range to which the outlet water temperature belongs according to a relative relationship between the outlet water temperature of the water tank and a set temperature; when it is determined that the user is in the water use stage or that the water tank is in the water production stage, determining whether to control the hot water pump in the heat pump system to start and operate according to at least one of the water temperature range and the hot water pump start-up condition.

[0005] Optionally, the steps of determining whether the user is in the water use stage and determining whether the water tank is in the water production stage according to at least one of the decrease rate of the inlet water temperature and the decrease rate of the outlet water temperature include: when the decrease rate of the inlet water temperature is greater than or equal to a preset threshold, determining that the user is in the water use stage; or, when the decrease rate of the inlet water temperature is less than the preset threshold and the decrease rate of the outlet water temperature is greater than or equal to the preset threshold, determining that the user is in the water use stage; when the decrease rate of the inlet water temperature is less than the preset threshold, determining that the water tank is in the water production stage.

[0006] Optionally, the water temperature interval includes a first water temperature interval, a second water temperature interval and a third water temperature interval; the set temperature includes a first set temperature and a second set temperature; wherein the outlet water temperature of the first water temperature interval is lower than the outlet water temperature of the second water temperature interval, and the outlet water temperature of the second water temperature interval is lower than the outlet water temperature of the third water temperature interval; the step of determining the water temperature interval to which the outlet water temperature belongs according to the relative relationship between the outlet water temperature and the set temperature of the water tank comprises: when the outlet water temperature is lower than or equal to the first set temperature, determining that the water temperature interval to which the outlet water temperature belongs is the first water temperature interval; when the outlet water temperature is greater than the first set temperature and less than or equal to the second set temperature, determining that the water temperature interval to which the outlet water temperature belongs is the second water temperature interval; when the outlet water temperature is greater than the second set temperature, determining that the water temperature interval to which the outlet water temperature belongs is the third water temperature interval.

[0007] Optionally, when it is determined that the user is in the water use stage or the water tank is in the water production stage, the step of determining whether to control the hot water pump in the heat pump system to start and operate according to at least one of the water temperature range and the hot water pump start-up condition includes: when it is determined that the water tank is in the water production stage, determining whether to control the hot water pump in the heat pump system to start and operate according to the hot water pump start-up condition; when it is determined that the user is in the water use stage, determining whether to control the hot water pump in the heat pump system to start and operate according to the water temperature range and the hot water pump start-up condition.

[0008] Optionally, the water temperature interval includes a first water temperature interval, a second water temperature interval and a third water temperature interval; wherein, the outlet water temperature of the first water temperature interval is lower than the outlet water temperature of the second water temperature interval, and the outlet water temperature of the second water temperature interval is lower than the outlet water temperature of the third water temperature interval; when it is determined that the user is in the water use stage, the step of determining whether to control the hot water pump in the heat pump system to start and operate according to the water temperature interval and the hot water pump start-up condition includes: when it is determined that the user is in the water use stage and the outlet water temperature of the water tank is in the first water temperature interval or the third water temperature interval, determining whether to control the hot water pump in the heat pump system to start and operate according to the hot water pump start-up condition; when it is determined that the user is in the water use stage and the outlet water temperature of the water tank is in the second water temperature interval, turning off the hot water pump.

[0009] Optionally, the hot water pump start-up conditions include: receiving a hot water start-up signal sent by the user; the compressor in the heat pump system has no shutdown failure and the compressor shutdown time is greater than the set time; the water inlet temperature of the water tank is less than or equal to the hot water set temperature minus the hot water start-up temperature difference.

[0010] Optionally, the shutdown fault includes abnormal operation of the compressor or abnormal pressure of the circulating pump.

[0011] Optionally, the shutdown condition of the hot water pump includes any one of the following: receiving a shutdown signal sent by a user; detecting a shutdown failure of the compressor in the heat pump system; and the water inlet temperature of the water tank is greater than or equal to the hot water set temperature.

[0012] In a second aspect, an embodiment of the present invention provides a control system for a heat pump system, including a controller for executing the method for controlling the water temperature of a water tank provided by any embodiment of the present invention.

[0013] In a third aspect, an embodiment of the present invention provides a heat pump system, including the control system of the heat pump system provided in the second aspect.

[0014] The water temperature control method of the water tank provided by the embodiment of the present invention can determine whether the user is in the water use stage and whether the water tank is in the water production stage by monitoring the decreasing rate of the water inlet temperature and the water outlet temperature, so as to avoid the excessive mixing of cold and hot water caused by the unreasonable start of the hot water pump when using water, ensure that the outlet water temperature is relatively stable, improve the user's comfort in using hot water, and meet the user's demand for stable water temperature. According to the water temperature range and the hot water pump start-up conditions, the hot water pump can be flexibly controlled to start and stop, which reduces unnecessary operation and improves energy efficiency.

[0015] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0017] Figure 1 is a structural schematic diagram of a heat pump system provided by an embodiment of the present invention;

[0018] Figure 2 is a flow chart of a method for controlling water temperature in a water tank provided by an embodiment of the present invention;

[0019] Figure 3 is a flow chart of another method for controlling water temperature in a water tank provided by an embodiment of the present invention;

[0020] Figure 4 is a flow chart of another method for controlling water temperature in a water tank provided by an embodiment of the present invention;

[0021] Figure 5 is a flow chart of another method for controlling water temperature in a water tank provided by an embodiment of the present invention;

[0022] Figure 6 This is a flow chart of another method for controlling water temperature in a water tank provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0023] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0024] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0025] In order to solve the problems of the prior art, an embodiment of the present application provides a method for controlling the water temperature of a water tank. The following first introduces a heat pump system to which the method for controlling the water temperature of a water tank provided by an embodiment of the present application can be applied. Figure 1 Schematic diagram of a heat pump system provided by an embodiment of the present invention. Figure 1 As shown, the heat pump system 1 includes a compressor 100, a first heat exchanger 200, a water tank 300, a hot water pump 400, a four-way valve 500, a second heat exchanger 600 and a third heat exchanger 700; wherein the four-way valve 500 has an a port 510, a b port 520, a c port 530 and a d port 540, the a port 510 is connected to the c port 530, and the b port 520 is connected to the d port 540; the air inlet end of the compressor 100 is connected to the c port 530, the exhaust end of the compressor 100 is connected to the first heat exchanger 200, and the a port 510 is connected to the first heat exchanger 200; the water tank 300 is connected to the first heat exchanger 200 through the hot water pump 400, so that the cold water in the water tank 300 exchanges heat with the refrigerant in the first heat exchanger 200 and heats the cold water. One side of the second heat exchanger 600 is connected to the b port 520, and the other side is connected to the third heat exchanger 700, and the d port 540 is connected to the third heat exchanger 700; the third heat exchanger 700 is connected to the water inlet pipe 90 and the water outlet pipe 91 of the air conditioner so that the refrigerant in the third heat exchanger 700 can exchange heat with the water in the water inlet pipe 90.

[0026] like Figure 1 As shown, the heat pump system also includes a first pipeline 10 and a second pipeline 20, the two ends of the first pipeline 10 are respectively connected to the first heat exchanger 200 and the water tank 300, and the two ends of the second pipeline 20 are respectively connected to the first heat exchanger 200 and the water tank 300, so that the first heat exchanger 200, the second pipeline 20, the water tank 300 and the first pipeline 10 form a closed loop; the hot water pump 400 is arranged on the first pipeline 10, and the hot water pump 400 is configured to pump the cold water in the water tank 300 into the first heat exchanger 200.

[0027] The water tank 300 has a cold water inlet 310 and a hot water outlet 320. The cold water inlet 310 is located on the side close to the first pipeline 10, and the hot water outlet 320 is located on the side close to the second pipeline 20, which reduces the flow paths of cold water and hot water, thereby facilitating the hot water pump 400 to pump the cold water in the water tank 300 into the first heat exchanger 200 in time, and also facilitating the hot water outlet 320 to discharge the hot water in time for people to use, thereby improving efficiency.

[0028] The heat pump system also includes a third pipeline 30, a fourth pipeline 40 and a fifth pipeline 50. The two ends of the third pipeline 30 are respectively connected to the exhaust end of the compressor 100 and the first heat exchanger 200, the two ends of the fourth pipeline 40 are respectively connected to the first heat exchanger 200 and the a port 510, and the two ends of the fifth pipeline 50 are respectively connected to the intake end of the compressor 100 and the c port 530.

[0029] The heat pump system also includes a sixth pipeline 60, a seventh pipeline 70 and an eighth pipeline 80. The two ends of the sixth pipeline 60 are respectively connected to the b port 520 and the second heat exchanger 600, the two ends of the seventh pipeline 70 are respectively connected to the second heat exchanger 600 and the third heat exchanger 700, and the two ends of the eighth pipeline 80 are respectively connected to the third heat exchanger 700 and the d port 540.

[0030] The heat pump system further includes an electronic expansion valve 800 , which is disposed on the seventh pipeline 70 . The electronic expansion valve 800 is configured to throttle and reduce the pressure of the refrigerant in the seventh pipeline 70 .

[0031] Optionally, the first heat exchanger 200 in this embodiment is a shell-and-tube heat exchanger, the second heat exchanger 600 is a fin heat exchanger, and the third heat exchanger 700 is a plate heat exchanger.

[0032] Figure 2 This is a flow chart of a method for controlling the water temperature of a water tank provided by an embodiment of the present invention. The method of this embodiment can be executed by a control unit of a heat pump system, which can be implemented in software and / or hardware and can be integrated in devices such as vehicle-mounted devices, energy storage devices, and electric tools. Figure 1 and Figure 2 , the water temperature control method of the water tank includes:

[0033] S101, monitoring the water inlet temperature and the water outlet temperature of the water tank.

[0034] Specifically, temperature sensors are provided at the cold water inlet 310 and the hot water outlet 320 of the water tank 300 to obtain the temperature data of the water inlet temperature and the water outlet temperature in real time. These data are the basis for subsequent judgment and decision-making, and can reflect the temperature change of the water in the water tank and the temperature state of the water tank and the external water exchange.

[0035] S102: Determine whether the user is in a water use stage and whether the water tank is in a water production stage according to at least one of a decreasing rate of the water inlet temperature and a decreasing rate of the water outlet temperature.

[0036] Specifically, the decreasing rate of the inlet water temperature refers to the temperature decrease of the water entering the water tank 300 per unit time (such as per minute, etc.). The decreasing rate of the outlet water temperature refers to the temperature decrease of the water flowing out of the water tank or related equipment per unit time.

[0037] Install high-precision temperature sensors at the water inlet and outlet of the water tank to ensure that the sensor installation position can accurately measure the water flow temperature and is not interfered by external factors. Collect temperature data at fixed time intervals (such as every second, every 5 seconds, etc.) to form a time-temperature data sequence. The higher the acquisition frequency, the more accurate the subsequent calculated temperature drop rate.

[0038] Assuming that the inlet water temperatures collected at time series t1 and t2 (t2>t1) are T11 and T12 respectively, the calculation formula for the inlet water temperature drop rate V1 is: If the inlet water temperature is 30°C at time t1 and 28°C at time t2 (t2-t1=10 seconds later), then the inlet water temperature drop rate V1=0.2°C / second. The outlet water temperature drop rate V2 is calculated in the same way. The outlet water temperatures collected at time t1 and t2 are T21 and T22 respectively.

[0039] Optionally, when the decreasing rate of the inlet water temperature is greater than or equal to a preset threshold, or when the decreasing rate of the inlet water temperature is less than the preset threshold and the decreasing rate of the outlet water temperature is greater than or equal to the preset threshold, it can be determined that the user is in the water use stage. This is because when the user uses water, hot water flows out of the water tank 300 and cold water is replenished, which causes the inlet water temperature and the outlet water temperature to change. This water use behavior can be captured by monitoring the temperature decrease rate.

[0040] When the rate of decrease of the inlet water temperature is less than the preset threshold, it is determined that the water tank is in the water production stage. In the water production stage, the water tank is mainly heating water, at which time the cold water inflow is relatively stable and the rate of decrease of the inlet water temperature is low.

[0041] S103, determining the water temperature range to which the outlet water temperature belongs according to the relative relationship between the outlet water temperature of the water tank and the set temperature.

[0042] Specifically, the set temperature is divided into a first set temperature and a second set temperature, thereby dividing the first water temperature interval, the second water temperature interval and the third water temperature interval. The outlet water temperature of the first water temperature interval is lower than the outlet water temperature of the second water temperature interval, and the outlet water temperature of the second water temperature interval is lower than the outlet water temperature of the third water temperature interval. For example, when the outlet water temperature is less than or equal to the first set temperature, the water temperature interval to which the outlet water temperature belongs is determined to be the first water temperature interval. When the outlet water temperature is greater than the first set temperature and less than or equal to the second set temperature, the water temperature interval to which the outlet water temperature belongs is determined to be the second water temperature interval. When the outlet water temperature is greater than the second set temperature, the water temperature interval to which the outlet water temperature belongs is determined to be the third water temperature interval. Exemplarily, the first set temperature is 45°C and the second set temperature is 55°C.

[0043] S104: When it is determined that the user is in a water use stage or the water tank is in a water production stage, determine whether to control the hot water pump in the heat pump system to start operation according to at least one of the water temperature range and the hot water pump start condition.

[0044] When it is determined that the water tank is in the water production stage, the hot water pump is started according to the hot water pump start-up conditions. The start-up conditions usually include receiving the hot water start-up signal sent by the user, the compressor in the heat pump system has no shutdown failure and the compressor shutdown time is greater than the set time, the water inlet temperature of the water tank is less than or equal to the hot water set temperature minus the hot water start-up temperature difference, etc. Only when these conditions are met at the same time will the hot water pump be started to produce water.

[0045] When it is determined that the user is in the water use stage, the hot water pump is controlled in combination with the water temperature range and the hot water pump start-up conditions. If the water outlet temperature of the water tank is in the first water temperature range or the third water temperature range, whether to start the hot water pump is determined according to the hot water pump start-up conditions; if the water outlet temperature is in the second water temperature range, the hot water pump is turned off. This is because the water temperature in the second water temperature range may have met the basic needs of the user. Turning off the hot water pump can avoid unnecessary energy consumption and water temperature fluctuations caused by excessive mixing of cold and hot water in the water tank.

[0046] The water temperature control method of the water tank provided by the embodiment of the present invention can determine whether the user is in the water use stage and whether the water tank is in the water production stage by monitoring the decreasing rate of the water inlet temperature and the water outlet temperature, so as to avoid the excessive mixing of cold and hot water caused by the unreasonable start of the hot water pump when using water, ensure that the outlet water temperature is relatively stable, improve the user's comfort in using hot water, and meet the user's demand for stable water temperature. According to the water temperature range and the hot water pump start-up conditions, the hot water pump can be flexibly controlled to start and stop, which reduces unnecessary operation and improves energy efficiency.

[0047] Figure 3FIG. 1 is a flow chart of another method for controlling the water temperature of a water tank provided by an embodiment of the present invention. Figure 3 As shown, the method for controlling the water temperature of the water tank includes:

[0048] S201, monitoring the water inlet temperature and the water outlet temperature of the water tank.

[0049] S202. When the decreasing rate of the inlet water temperature is greater than or equal to a preset threshold, it is determined that the user is in the water use stage; or, when the decreasing rate of the inlet water temperature is less than the preset threshold and the decreasing rate of the outlet water temperature is greater than or equal to the preset threshold, it is determined that the user is in the water use stage.

[0050] The preset threshold is a pre-set reference value, which is determined based on the characteristics of the device, usage scenarios and other factors. This threshold is used as a standard to determine whether the rate of decrease in the inlet water temperature is abnormal. For example, after testing and analysis, the preset threshold of the rate of decrease in the inlet water temperature is set to 3°C / minute.

[0051] The first judgment condition is: "When the rate of decrease of the inlet water temperature is greater than or equal to the preset threshold value". When this happens, it means that the inlet water temperature drops relatively quickly. Under normal circumstances, when there is no large amount of water use, the rate of decrease of the inlet water temperature is relatively stable and small. When the rate of decrease of the inlet water temperature increases to equal or exceed the preset threshold value, it is likely that the user is using water and the water in the water tank is consumed in large quantities, resulting in an increase in the amount of replenished water. Due to the difference between the inlet water temperature and the original water temperature in the water tank, the rate of decrease of the inlet water temperature is accelerated. For example, if the preset threshold is 3°C / minute, and the actual rate of decrease of the inlet water temperature reaches 4°C / minute, it can be judged that the user is in the water use stage.

[0052] The second judgment condition is: "When the rate of decrease of the inlet water temperature is less than the preset threshold, and the rate of decrease of the outlet water temperature is greater than or equal to the preset threshold". In this case, the rate of decrease of the inlet water temperature is less than the preset threshold, indicating that the replenishment of the inlet water is relatively stable, and there is no significant increase in the inlet water due to large amounts of water use. However, the rate of decrease of the outlet water temperature is greater than or equal to the preset threshold, which indicates that the temperature of the water flowing out of the water tank varies greatly and the outflow speed may be faster. Because in the normal non-water use state, the outlet water temperature of the water tank is relatively stable and the rate of decrease is small. When the rate of decrease of the outlet water temperature increases to equal or exceed the preset threshold, it is likely that the user is using water, and a large amount of water flows out of the water tank, causing the rate of decrease of the outlet water temperature to accelerate. For example, the rate of decrease of the inlet water temperature is 2°C / minute (less than the preset threshold of 3°C / minute), and the rate of decrease of the outlet water temperature is 4°C / minute (greater than the preset threshold of 3°C / minute). At this time, it can also be determined that the user is in the water use stage.

[0053] S203: When the decreasing rate of the inlet water temperature is less than a preset threshold, it is determined that the water tank is in the water production stage.

[0054] Specifically, in the water production stage of the water tank (such as when heating the water in the water tank), the focus of the water tank is to change the temperature and other parameters of the water in the water tank, rather than replenishing or consuming a large amount of water. At this time, the water inlet situation is relatively stable, and there is no rapid water replenishment due to large amounts of water use, so the rate of decrease in the inlet temperature is relatively small. For example, the preset threshold is 3°C / minute, and the actual measured rate of decrease in the inlet temperature is 1°C / minute, which is less than the preset threshold. According to this judgment logic, it can be determined that the water tank is in the water production stage. When the rate of decrease in the inlet temperature is less than the preset threshold, it is determined that the water tank is in the water production stage. This enables the control system to accurately identify the water production state and then reasonably arrange various operations in the water production process. For example, in the water production stage, the operation of the heat pump system can be accurately controlled according to the water temperature in the water tank, avoiding unnecessary water production operations in the non-water production stage, improving energy utilization efficiency, and reducing energy consumption.

[0055] S204, determining the water temperature range to which the outlet water temperature belongs according to the relative relationship between the outlet water temperature of the water tank and the set temperature.

[0056] S205: When it is determined that the user is in the water use stage or the water tank is in the water production stage, determine whether to control the hot water pump in the heat pump system to start running according to at least one of the water temperature range and the hot water pump start condition.

[0057] By accurately determining the water use stage and the water production stage, the control system of this embodiment can reasonably allocate energy during the water use stage to meet user needs while avoiding energy waste; in the water production stage, the water production process is optimized to improve water production efficiency and reduce energy consumption in the water production process.

[0058] Figure 4 FIG. 1 is a flow chart of another method for controlling the water temperature of a water tank provided by an embodiment of the present invention. Figure 4 As shown, the method for controlling the water temperature of the water tank includes:

[0059] S301, monitoring the water inlet temperature and the water outlet temperature of the water tank.

[0060] S302: Determine whether the user is in a water use stage and whether the water tank is in a water production stage according to at least one of a decreasing rate of the water inlet temperature and a decreasing rate of the water outlet temperature.

[0061] S303: When the outlet water temperature is less than or equal to the first set temperature, determine that the water temperature interval to which the outlet water temperature belongs is the first water temperature interval.

[0062] S304: When the outlet water temperature is greater than the first set temperature and less than or equal to the second set temperature, determine that the water temperature interval to which the outlet water temperature belongs is the second water temperature interval.

[0063] S305: When the outlet water temperature is greater than the second set temperature, determine that the water temperature interval to which the outlet water temperature belongs is the third water temperature interval.

[0064] S306: When it is determined that the user is in the water use stage or the water tank is in the water production stage, determine whether to control the hot water pump in the heat pump system to start running according to at least one of the water temperature range and the hot water pump start condition.

[0065] This embodiment divides the water temperature intervals by comparing the outlet water temperature with different set temperatures. After the water temperature intervals are clearly divided, the operation of the heating equipment can be reasonably controlled according to the water temperature intervals, which helps to optimize energy utilization. In the first water temperature interval, the equipment works at full capacity to increase the water temperature; when the water temperature is in the appropriate second water temperature interval, the equipment can reduce energy consumption and maintain the water temperature; in the third water temperature interval, unnecessary heating is reduced to avoid energy waste. In this way, while meeting the user's water demand, energy can be saved to the greatest extent and the cost of use can be reduced.

[0066] Figure 5 FIG. 1 is a flow chart of another method for controlling the water temperature of a water tank provided by an embodiment of the present invention. Figure 5 As shown, the method for controlling the water temperature of the water tank includes:

[0067] S401, monitoring the water inlet temperature and the water outlet temperature of the water tank.

[0068] S402: Determine whether the user is in a water use stage and whether the water tank is in a water production stage according to at least one of a decreasing rate of the water inlet temperature and a decreasing rate of the water outlet temperature.

[0069] S403, determining the water temperature range to which the water outlet temperature belongs according to the relative relationship between the water outlet temperature of the water tank and the set temperature.

[0070] S404: When it is determined that the water tank is in the water production stage, determine whether to control the hot water pump in the heat pump system to start running according to the hot water pump start condition.

[0071] Hot water pump start conditions are a set of pre-set rules or standards used to determine under what circumstances hot water should be started. Exemplarily, the hot water pump start conditions include: receiving a hot water start signal sent by a user, the compressor in the heat pump system has no shutdown fault and the compressor shutdown time is greater than the set time, and the water inlet temperature of the water tank is less than or equal to the hot water set temperature minus the hot water start temperature difference.

[0072] That is to say, the hot water pump can only be started when the user actively issues a command to turn on the hot water device. For example, the user sends a signal to turn on the hot water by operating the device's control panel, a mobile phone APP, etc.

[0073] The compressor is the core component of the heat pump system. It is responsible for compressing and transporting refrigerant to achieve heat transfer. If the compressor has a shutdown failure, such as abnormal operation of the compressor or abnormal pressure of the circulating pump, the heat pump system may not work properly. At this time, starting the hot water pump cannot obtain normal hot water supply, and may even cause further damage to the system. Therefore, only consider starting the hot water pump after confirming that the compressor has no shutdown failure. After the compressor is shut down, it is necessary to wait for a period of time (that is, greater than the set time) to allow the pressure, temperature and other parameters inside the system to return to a relatively stable state before starting the hot water pump and compressor. This can avoid starting the compressor in an unstable state, reduce equipment wear and failure risks, and extend the service life of the equipment.

[0074] The hot water set temperature is the desired hot water temperature value preset by the user or the system, such as 50°C. The hot water start temperature difference is a set temperature difference value, such as 5°C. When the water inlet temperature of the water tank is less than or equal to "the hot water set temperature minus the hot water start temperature difference" (i.e. 50°C-5°C=45°C), it means that the water temperature in the water tank has not reached the desired hot water temperature. At this time, the hot water pump is started, and the heat pump system is used to heat the water in the water tank, etc., so that the water temperature in the water tank can gradually rise to the set temperature to meet the user's demand for hot water.

[0075] S405: When it is determined that the user is in the water use stage, determine whether to control the hot water pump in the heat pump system to start running according to the water temperature range and the hot water pump start condition.

[0076] Optionally, when it is determined that the user is in the water use stage and the outlet water temperature of the water tank is in the first water temperature interval or the third water temperature interval, it is determined whether to control the hot water pump in the heat pump system to start running according to the hot water pump start condition. When it is determined that the user is in the water use stage and the outlet water temperature of the water tank is in the second water temperature interval, the hot water pump is turned off.

[0077] Specifically, if the outlet water temperature is in the first water temperature interval, it means that the water temperature flowing out of the water tank is low and may not meet the user's demand for hot water. At this time, in order to adjust the water temperature, it is necessary to exit the water use stage and enter the water production stage. At the same time, it is determined whether to start the hot water pump based on the hot water pump start-up conditions (such as receiving the hot water start-up signal sent by the user, the compressor in the heat pump system has no shutdown failure and the compressor shutdown time is greater than the set time, the water inlet temperature of the water tank is less than or equal to the hot water set temperature minus the hot water start-up temperature difference, etc.). If these hot water pump start-up conditions are met at the same time, the hot water pump is controlled to start and run, and the heat pump system is cooperated to heat or otherwise process the water in the water tank to increase the water temperature; if the hot water pump start-up conditions are not met, the hot water pump is not started.

[0078] When the outlet water temperature is in the third water temperature range, it means that the water temperature in the water tank is too high. At this time, the water production stage is exited and the water use stage is entered. At the same time, whether to start the hot water pump is determined based on the hot water pump start-up conditions. Starting the hot water pump can transport the hot water in the water tank out and introduce relatively low-temperature water at the same time, thereby adjusting the water temperature in the water tank.

[0079] The second water temperature range is generally considered to be a relatively suitable water temperature range that can meet the general water needs of users. In this case, turning off the hot water pump can avoid unnecessary energy consumption, because the water temperature in the water tank is already in the appropriate range, and the hot water pump does not need to continue working to adjust the water temperature. At the same time, turning off the hot water pump also helps reduce equipment wear and tear and extend the service life of the equipment.

[0080] In some embodiments, the shutdown condition of the hot water pump includes any one of the following: receiving a shutdown signal sent by a user; detecting a shutdown failure of the compressor in the heat pump system; the water inlet temperature of the water tank is greater than or equal to the hot water set temperature.

[0081] This embodiment controls the hot water pump according to different situations, reducing the unreasonable operation of the equipment. In the water production stage, the hot water pump is started according to the start-up conditions, avoiding the interference of the abnormal start-up of the hot water pump on the water production process; in the water use stage, the hot water pump is operated under appropriate working conditions according to the comprehensive judgment of the water temperature range and the start-up conditions of the hot water pump, reducing the equipment wear caused by frequent start-stop or improper operation, extending the service life of the equipment, reducing the probability of equipment failure, and improving the stability and reliability of the entire heat pump system.

[0082] Figure 6 FIG. 1 is a flow chart of another method for controlling the water temperature of a water tank provided by an embodiment of the present invention. Figure 6 As shown, the method for controlling the water temperature of the water tank includes:

[0083] S501, monitoring the water inlet temperature and the water outlet temperature of the water tank.

[0084] S502. When the decreasing rate of the inlet water temperature is greater than or equal to a preset threshold, it is determined that the user is in the water use stage; or, when the decreasing rate of the inlet water temperature is less than the preset threshold and the decreasing rate of the outlet water temperature is greater than or equal to the preset threshold, it is determined that the user is in the water use stage.

[0085] S503: When the decreasing rate of the inlet water temperature is less than a preset threshold, it is determined that the water tank is in the water production stage.

[0086] S504: When the outlet water temperature is less than or equal to the first set temperature, determine that the water temperature interval to which the outlet water temperature belongs is the first water temperature interval.

[0087] S505: When the outlet water temperature is greater than the first set temperature and less than or equal to the second set temperature, determine that the water temperature interval to which the outlet water temperature belongs is the second water temperature interval.

[0088] S506: When the outlet water temperature is greater than the second set temperature, determine that the water temperature interval to which the outlet water temperature belongs is the third water temperature interval.

[0089] S507: When it is determined that the water tank is in the water production stage, determine whether to control the hot water pump in the heat pump system to start running according to the hot water pump start condition.

[0090] S508: When it is determined that the user is in the water use stage, determine whether to control the hot water pump in the heat pump system to start running according to the water temperature range and the hot water pump start condition.

[0091] This embodiment can judge the user's water use stage and the water tank water production stage by real-time monitoring of the water inlet and outlet temperatures of the water tank, combined with the comparison of the temperature drop rate with the preset threshold value, which is conducive to avoiding the excessive mixing of cold and hot water caused by unreasonable start-up of the hot water pump when using water, ensuring that the outlet water temperature is relatively stable, improving the user's comfort in using hot water, and meeting the user's demand for stable water temperature. According to the water temperature range and the hot water pump start-up conditions, the hot water pump is flexibly controlled to start and stop, which reduces unnecessary operation and improves energy efficiency. In the water tank water production stage, the operation of the hot water pump is controlled according to the hot water pump start-up conditions to avoid unnecessary energy consumption. In the user's water use stage, the start and stop of the hot water pump are reasonably determined in combination with the water temperature range and the hot water pump start-up conditions, such as shutting down the hot water pump in the middle water temperature range where the water temperature is suitable, thereby significantly improving energy efficiency and reducing long-term operating costs.

[0092] Based on the same inventive concept, an embodiment of the present invention further provides a control system for a heat pump system, including a controller for executing the method for controlling the water temperature of a water tank provided in any embodiment of the present invention. The control system has the beneficial effects of any embodiment of the present invention described above.

[0093] An embodiment of the present invention provides a heat pump system, including a control system of the heat pump system provided by the embodiment of the present invention.

[0094] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the present invention can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of the present invention can be achieved, and this document does not limit this.

[0095] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for controlling water temperature in a water tank, characterized in that: The water tank is arranged in a heat pump system, and the method for controlling the water temperature of the water tank includes: Monitoring the water inlet temperature and the water outlet temperature of the water tank; Determining whether the user is in a water use stage and determining whether the water tank is in a water production stage according to at least one of the decreasing rate of the water inlet temperature and the decreasing rate of the water outlet temperature; Determine the water temperature range to which the outlet water temperature belongs according to the relative relationship between the outlet water temperature of the water tank and the set temperature; When it is determined that the user is in the water use stage or the water tank is in the water production stage, it is determined whether to control the hot water pump in the heat pump system to start running according to at least one of the water temperature range and the hot water pump start condition.

2. The method for controlling the water temperature of a water tank according to claim 1, characterized in that: The step of determining whether the user is in the water use stage and determining whether the water tank is in the water production stage according to at least one of the decreasing rate of the water inlet temperature and the decreasing rate of the water outlet temperature comprises: When the decreasing rate of the inlet water temperature is greater than or equal to a preset threshold, it is determined that the user is in the water use stage; or, when the decreasing rate of the inlet water temperature is less than the preset threshold and the decreasing rate of the outlet water temperature is greater than or equal to the preset threshold, it is determined that the user is in the water use stage; When the decreasing rate of the inlet water temperature is less than the preset threshold, it is determined that the water tank is in the water production stage.

3. The method for controlling the water temperature of a water tank according to claim 1, characterized in that: The water temperature interval includes a first water temperature interval, a second water temperature interval and a third water temperature interval; the set temperature includes a first set temperature and a second set temperature; wherein the outlet water temperature of the first water temperature interval is lower than the outlet water temperature of the second water temperature interval, and the outlet water temperature of the second water temperature interval is lower than the outlet water temperature of the third water temperature interval; The step of determining the water temperature interval to which the outlet water temperature belongs according to the relative relationship between the outlet water temperature of the water tank and the set temperature comprises: When the outlet water temperature is less than or equal to the first set temperature, determining that the water temperature interval to which the outlet water temperature belongs is the first water temperature interval; When the outlet water temperature is greater than the first set temperature and less than or equal to the second set temperature, determining that the water temperature interval to which the outlet water temperature belongs is the second water temperature interval; When the outlet water temperature is greater than the second set temperature, the water temperature interval to which the outlet water temperature belongs is determined to be the third water temperature interval.

4. The method for controlling the water temperature of a water tank according to claim 1, characterized in that: When it is determined that the user is in the water use stage or the water tank is in the water production stage, the step of determining whether to control the hot water pump in the heat pump system to start operation according to at least one of the water temperature range and the hot water pump start condition includes: When it is determined that the water tank is in the water production stage, determining whether to control the hot water pump in the heat pump system to start operation according to the hot water pump start condition; When it is determined that the user is in the water use stage, it is determined whether to control the hot water pump in the heat pump system to start running according to the water temperature range and the hot water pump start condition.

5. The method for controlling the water temperature of a water tank according to claim 4, characterized in that: The water temperature intervals include a first water temperature interval, a second water temperature interval and a third water temperature interval; wherein the outlet water temperature of the first water temperature interval is lower than the outlet water temperature of the second water temperature interval, and the outlet water temperature of the second water temperature interval is lower than the outlet water temperature of the third water temperature interval; When it is determined that the user is in the water use stage, the step of determining whether to control the hot water pump in the heat pump system to start running according to the water temperature range and the hot water pump start condition includes: When it is determined that the user is in the water use stage and the outlet water temperature of the water tank is in the first water temperature interval or the third water temperature interval, determining whether to control the hot water pump in the heat pump system to start running according to the hot water pump start condition; When it is determined that the user is in the water use stage and the outlet water temperature of the water tank is in the second water temperature range, the hot water pump is turned off.

6. The method for controlling the water temperature of a water tank according to any one of claims 1 to 5, characterized in that: The hot water pump start-up conditions include: Receive the hot water start signal sent by the user; The compressor in the heat pump system has no shutdown failure and the compressor shutdown time is greater than the set time; The water inlet temperature of the water tank is less than or equal to the hot water set temperature minus the hot water start-up temperature difference.

7. The method for controlling the water temperature of a water tank according to claim 6, characterized in that: The shutdown failure includes abnormal operation of the compressor or abnormal pressure of the circulating pump.

8. The method for controlling the water temperature of a water tank according to claim 1, characterized in that: The shut-down condition of the hot water pump includes any one of the following: Receive a shutdown signal sent by the user; Detecting that a compressor in the heat pump system has a shutdown fault; The water inlet temperature of the water tank is greater than or equal to the hot water set temperature.

9. A control system for a heat pump system, characterized in that: A controller is included for executing the method for controlling the water temperature of a water tank as described in any one of claims 1 to 8.

10. A heat pump system, characterized in that: A control system comprising the heat pump system according to claim 9.

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