Control method of heat pump water heater

Abstract

The present invention belongs to the field of household appliance technology, and specifically relates to a control method for a heat pump water heater. The present invention aims to address the problem of existing heat pump water heaters being affected by the high-temperature water in the upper portion of the water tank, resulting in a high condenser temperature and poor heat exchange efficiency. The heat pump water heater of the present invention includes a first condenser and a second condenser arranged above and below the water tank. The refrigerant outlet of the first condenser is connected to the refrigerant inlet of the second condenser via a first refrigerant branch pipe, and the first refrigerant branch pipe is provided with a regulating valve. The refrigerant inlet of the second condenser is also connected to the refrigerant main pipe via a second refrigerant branch pipe, and the second refrigerant branch pipe is provided with an on-off valve. A controller is respectively connected to the regulating valve and the on-off valve, and is used to control the on-off valve to open in stratified heating mode. The regulating valve opening is reduced to 20-30 degrees, allowing the refrigerant in the refrigerant main pipe to enter the second condenser through the second refrigerant branch pipe, thereby achieving stratified heating of the water inside the water tank and improving heat exchange efficiency.

Description

Technical Field

[0001] The present invention belongs to the technical field of household appliances, and in particular relates to a control method for a heat pump water heater. Background Art

[0002] A heat pump water heater is a device that uses a refrigerant to absorb low-temperature heat energy from the air and transfer it to a water tank to produce hot water. It is becoming increasingly popular due to its advantages such as energy saving and high environmental protection.

[0003] Because water density decreases as temperature rises, the water temperature at the top of the heat pump water heater tank is higher than that at the bottom. When the user uses water, cold water enters the bottom of the tank, which then drains the hot water from the top of the tank out the outlet, causing the water temperature in the tank to stratify. Typically, a temperature sensor is installed at 1 / 2 or 1 / 3 of the tank's height. When the temperature detected by the sensor falls below a preset value, the heat pump water heater starts heating the water in the tank.

[0004] However, affected by the high-temperature water on the upper part of the water tank, the temperature of the condenser is high, the heat exchange efficiency is poor, and the performance and life of the condenser are affected. Summary of the Invention

[0005] In order to solve the above problems in the prior art, that is, to solve the problem that the existing heat pump water heater is affected by the high temperature water in the upper part of the water tank, the temperature of the condenser is high and the heat exchange efficiency is poor, the present invention provides a control method for a heat pump water heater.

[0006] The heat pump water heater includes: a water tank, an evaporator, a compressor, a first condenser, a second condenser and a controller; the water tank is divided into a first heating area and a second heating area along the height direction, and the first condenser is covered on the outside of the first heating area, and the second condenser is covered on the outside of the second heating area; the refrigerant inlet of the first condenser is connected to the refrigerant outlet of the compressor, and the refrigerant outlet of the first condenser is connected to the refrigerant inlet of the second condenser through a first refrigerant branch pipe; and the refrigerant inlet of the second condenser is also connected to the refrigerant outlet of the evaporator through a second refrigerant branch pipe, and the refrigerant outlet of the second condenser is connected to the refrigerant inlet of the evaporator; a regulating valve is installed on the first refrigerant branch pipe, and a switch valve is installed on the second refrigerant branch pipe, and the controller is communicated with the switch and the regulating valve respectively; the control method of the heat pump water heater includes: the controller starts the stratified heating mode in response to the stratified heating instruction, controls the opening of the regulating valve to be reduced to 20~30B according to the stratified heating mode, and opens the switch valve.

[0007] In the optional technical solution of the control method of the above-mentioned heat pump water heater, the stratified heating mode includes: obtaining the water temperature of the first heating area and the water temperature of the second heating area; the controller controls the opening of the regulating valve and the opening and closing of the switch valve according to the temperature difference between the water temperature of the first heating area and the water temperature of the second heating area.

[0008] In an optional technical solution of the control method of the above-mentioned heat pump water heater, when the temperature difference between the water temperature of the first heating area and the water temperature of the second heating area is greater than the first preset temperature, the controller controls the opening of the regulating valve to be reduced to 20~30B, and the switch valve is opened.

[0009] In an optional technical solution of the control method of the above-mentioned heat pump water heater, the controller also starts a rapid heating mode in response to a rapid heating instruction, controls the opening of the regulating valve to increase according to the rapid heating mode, and adjusts the switch valve from an open state to a closed state.

[0010] In the optional technical solution of the control method of the above-mentioned heat pump water heater, the rapid heating mode includes: obtaining the water temperature of the first heating area and the condensation temperature of the refrigerant outlet of the first condenser; the controller controls the opening of the regulating valve and the opening and closing of the switch valve according to the difference between the water temperature of the first heating area and the condensation temperature of the refrigerant outlet of the first condenser.

[0011] In the optional technical solution of the control method of the above-mentioned heat pump water heater, when the difference between the water temperature of the first heating area and the condensing temperature of the refrigerant outlet of the first condenser is greater than the target heat exchange temperature difference, the controller controls the regulating valve to increase the opening and controls the switch valve to be adjusted from an open state to a closed state; when the difference between the water temperature of the first heating area and the condensing temperature of the refrigerant outlet of the first condenser is less than or equal to the target heat exchange temperature difference, the controller controls the regulating valve to decrease the opening and controls the switch valve to be adjusted from an open state to a closed state.

[0012] In the optional technical solution of the control method of the above-mentioned heat pump water heater, before controlling the opening of the regulating valve to increase according to the rapid heating mode and adjusting the switch valve from an open state to a closed state, it also includes: the controller controls the regulating valve to adjust the opening to 200~400B and maintains it for a preset time.

[0013] In the optional technical solution of the control method of the above-mentioned heat pump water heater, the controller also starts the full tank heating mode in response to the full tank heating instruction, controls the opening of the regulating valve to increase according to the full tank heating mode, and adjusts the switch valve from an open state to a closed state.

[0014] In the optional technical solution of the control method of the above-mentioned heat pump water heater, the full-tank heating mode includes: obtaining the water temperature of the first heating area and the water temperature of the second heating area; the controller controls the opening of the regulating valve and the opening and closing of the switch valve according to the temperature difference between the water temperature of the first heating area and the water temperature of the second heating area.

[0015] In an optional technical solution of the control method of the above-mentioned heat pump water heater, when the temperature difference between the water temperature of the first heating area and the water temperature of the second heating area is less than or equal to the first preset temperature, the controller controls the opening of the regulating valve to increase, and controls the switch valve to adjust from an open state to a closed state.

[0016] Those skilled in the art will appreciate that the heat pump water heater of the present invention includes a water tank, an evaporator, a compressor, a first condenser, a second condenser, and a controller. The water tank is divided into a first heating region and a second heating region along its height, with the first condenser surrounding the first heating region and the second condenser surrounding the second heating region. The refrigerant inlet of the first condenser is connected to the refrigerant outlet of the compressor, and the refrigerant outlet of the first condenser is connected to the refrigerant inlet of the second condenser via a first refrigerant branch pipe. The refrigerant inlet of the second condenser is also connected to the refrigerant outlet of the evaporator via a second refrigerant branch pipe, and the refrigerant outlet of the second condenser is connected to the refrigerant inlet of the evaporator. A regulating valve is installed on the first refrigerant branch pipe, and an on-off valve is installed on the second refrigerant branch pipe. The controller is communicatively connected to the on-off valve and the regulating valve, respectively. The control method of the heat pump water heater of the present invention includes the controller activating a stratified heating mode in response to a stratified heating instruction, controlling the regulating valve to reduce its opening to 20 to 30 degrees according to the stratified heating mode, and opening the on-off valve. Through the above configuration, in the stratified heating mode, only the second heating region of the water tank is heated, improving heat exchange efficiency and thereby improving the performance and life of the condenser. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The control method of the heat pump water heater of the present invention will be described below with reference to the accompanying drawings.

[0018] Figure 1 2 is a schematic diagram of the principle of a heat pump water heater according to an embodiment of the present invention;

[0019] Figure 2 2 is a schematic structural diagram of a water tank and a heat exchange device of a heat pump water heater according to an embodiment of the present invention;

[0020] Figure 3 Schematic diagram of the installation position of the temperature detection device of the heat pump water heater according to an embodiment of the present invention;

[0021] Figure 4 2 is a schematic structural diagram of a heat exchange device of a heat pump water heater according to an embodiment of the present invention;

[0022] Figure 5 4 is a flow chart of a control method for a heat pump water heater according to an embodiment of the present invention.

[0023] In the attached figure:

[0024] 1. Water tank; 10. Middle barrel; 11: First temperature measuring device; 12: Second temperature measuring device; 13. Head; 20: Heat exchange device; 201. First manifold; 202. Second manifold; 203. Microchannel flat tube; 204. Partition plate; 205. First partition plate; 206. Second partition plate; 207. Fixed pipe; 21. First condenser; 22. Second condenser; 30. Refrigerant main pipe; 31. First refrigerant branch pipe; 311: Regulating valve; 32. Second refrigerant branch pipe; 321. On-off valve; 33. Third refrigerant branch pipe; 34. Refrigerant return pipe; 35. Temperature sensing device; 4. Evaporator; 5. Compressor; 6. Four-way valve; 7. Main expansion valve; 8. Fan. DETAILED DESCRIPTION

[0025] First, those skilled in the art should understand that these embodiments are merely for explaining the technical principles of the present invention and are not intended to limit the scope of protection of the present invention. Those skilled in the art may adjust them as needed to suit specific applications.

[0026] Secondly, it should be noted that in the description of the present invention, terms such as "inside" and "outside" indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings. This is only for the convenience of description and does not indicate or imply that the device or component must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation on the present invention.

[0027] Furthermore, it should be noted that, in the description of the present invention, unless otherwise expressly specified or limited, the terms "connected" and "connection" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to direct connections, indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0028] A heat pump water heater consists of a water tank, evaporator, compressor, main expansion valve, and condenser. The main expansion valve is located between the condenser and evaporator. When the heat pump water heater is operating, the evaporator absorbs heat from the surrounding environment, causing the liquid refrigerant in the evaporator to vaporize and become a low-temperature, low-pressure gas. The low-temperature, low-pressure refrigerant then flows to the compressor, where it is compressed into a high-temperature, high-pressure gas. The high-temperature, high-pressure refrigerant enters the condenser in the water tank, where it condenses and releases heat, heating the water in the tank. Simultaneously, the heat released by the refrigerant turns it into a medium-temperature, high-pressure liquid. The medium-temperature, high-pressure refrigerant then transforms into a low-temperature, low-pressure gas-liquid two-phase state under the action of the main expansion valve, then flows back to the evaporator to absorb heat and vaporize, repeating the cycle to produce hot water.

[0029] Because water density decreases as temperature rises, the water temperature at the top of a heat pump water heater's tank is higher than that at the bottom. When a user uses water, cold water enters the bottom of the tank, discharging the hot water from the top through the outlet, causing the water in the tank to stratify. Typically, a temperature sensor is placed at 1 / 2 or 1 / 3 of the tank's height. When the temperature detected by the sensor falls below a preset value, the heat pump water heater activates and heats the water in the tank. However, due to the high temperature of the water at the top of the tank, the condenser temperature remains high, resulting in poor heat exchange efficiency. Furthermore, when the user's water usage is low, the user has to wait a long time for the water to heat up.

[0030] In view of this, the present invention provides a control method for a heat pump water heater, which includes an evaporator, a compressor, a water tank and a controller. Two condensers are arranged along the height direction of the water tank. The controller controls the amount of refrigerant entering the upper and lower condensers to achieve stratified heating, full tank heating and rapid heating of the water tank, thereby improving the heat exchange efficiency of the heat pump water heater.

[0031] The preferred technical solution of the control method of the heat pump water heater of the present invention will be described below in conjunction with the above-mentioned heat pump water heater.

[0032] See first Figures 1 to 4 , Figure 1 2 is a schematic diagram of the principle of a heat pump water heater according to an embodiment of the present invention; Figure 2 2 is a schematic structural diagram of a water tank and a heat exchange device of a heat pump water heater according to an embodiment of the present invention; Figure 3 Schematic diagram of the installation position of the temperature detection device of the heat pump water heater according to an embodiment of the present invention; Figure 4 1 is a structural diagram of a heat exchange device of a heat pump water heater according to an embodiment of the present invention.

[0033] like Figures 1 to 4As shown, the present invention provides a heat pump water heater, comprising: a water tank 1, an evaporator 4, a compressor 5, a first condenser 21, a second condenser 22, and a controller. The water tank 1 is divided into a first heating area and a second heating area along the height direction, and the first condenser 21 is wrapped around the outside of the first heating area, and the second condenser 22 is wrapped around the outside of the second heating area. The refrigerant inlet of the first condenser 21 is connected to the refrigerant outlet of the compressor 5, and the refrigerant outlet of the first condenser 21 is connected to the refrigerant inlet of the second condenser 22 via a first refrigerant branch pipe 31. The refrigerant inlet of the second condenser 22 is also connected to the refrigerant outlet of the compressor 5 via a second refrigerant branch pipe 32, and the refrigerant outlet of the second condenser 22 is connected to the refrigerant inlet of the evaporator 4. A regulating valve 311 is installed on the first refrigerant branch pipe 31, and an on-off valve 321 is installed on the second refrigerant branch pipe 32. The controller is communicatively connected to the on-off valve 321 and the regulating valve 311, respectively. The control method of the heat pump water heater of the present invention includes the controller starting the stratified heating mode in response to the stratified heating instruction, reducing the opening of the stratified heating mode control regulating valve 311 to 20-30B, and opening the switch valve 321.

[0034] Reference Figure 1 The refrigerant pipeline of the heat pump water heater of this embodiment sequentially connects the evaporator 4, compressor 5, and condenser to form a heat pump circuit for circulating refrigerant. The heat pump water heater of this embodiment also includes a four-way valve 6, a fan 8, and a main expansion valve 7. The fan 8 is located near the evaporator 4. The main expansion valve 7 is installed on the refrigerant return pipe 34 between the refrigerant outlet of the condenser and the refrigerant inlet of the evaporator 4. The main expansion valve 7 is used to regulate the flow of refrigerant. The four ports of the four-way valve 6 are respectively connected to the inlet and outlet ports of the compressor 5, the outlet of the evaporator 4, and the refrigerant main pipe 30.

[0035] The heat pump water heater of this embodiment also includes a water supply device, which is connected to the water inlet arranged at the bottom end of the water tank 1 to supply water to the water tank 1 to prevent the water in the water tank 1 from being exhausted; the top of the water tank 1 is provided with a water outlet connected to the outside, and then the hot water is discharged from the top to the outside of the water tank 1 for user use.

[0036] It is understood that the heating zones are divided according to the locations of the condensers within the water tank 1. For example, if two condensers are arranged in sequence along the height of the water tank 1, the water tank 1 is divided into two heating zones. Of course, if three condensers are arranged in sequence along the height of the water tank 1, the water tank 1 is divided into three heating zones. Although the present invention is described using the example of a water tank 1 divided into two heating zones, this is not limiting. If the water tank 1 is divided into three or more heating zones, the heating mode principles thereof are the same as those in the embodiments of the present invention.

[0037] In some examples, the first condenser 21 is connected to the refrigerant main pipe 30 through the third refrigerant branch pipe 33. At this time, no control valve is provided on the third refrigerant branch pipe 33. In the stratified heating mode, the control valve opening is reduced to 0-5B, so that the refrigerant in the refrigerant main pipe 30 can enter the first condenser 21 at a smaller flow rate, and most of the refrigerant enters the second condenser 22 to heat the second heating area. In this way, it is possible to avoid the refrigerant being continuously stored in the first condenser 21, and the high-temperature and high-pressure gas being heat-exchanged to form a low-temperature and high-pressure liquid, which increases the pressure in the first condenser 21 and affects the life of the first condenser 21.

[0038] In other examples, the first condenser 21 is connected to the refrigerant main pipe 30 via a third refrigerant branch pipe 33, and a solenoid valve is installed on the third refrigerant branch pipe 33. In the stratified heating mode, the controller controls the solenoid valve to close to prevent the refrigerant from entering the first condenser 21. The refrigerant in the condensation main pipe 30 passes through the second condenser 22 and heats the second heating area of the water tank 1.

[0039] It should be understood that in the embodiment of the present invention, the switch valve 321 can be a solenoid shut-off valve, a solenoid shut-off valve, etc., to control the flow and interruption of the refrigerant in the second refrigerant branch pipe 32. The regulating valve 311 is used to adjust the refrigerant flow in the first refrigerant branch pipe 31. For example, the regulating valve 311 can be an expansion valve.

[0040] The heat pump water heater of this embodiment also includes a controller, which is communicated with the switch valve 321 and the regulating valve 311 respectively. In the stratified heating mode, the opening of the regulating valve 311 is controlled to be adjusted to 0~5B, and the switch valve 321 is opened to allow most of the high-temperature and high-pressure refrigerant in the refrigerant main pipe 30 to enter the second condenser 22 through the second refrigerant branch pipe 32, and heat the water in the second heating area of the water tank 1 by exchanging heat with the water in the second heating area, thereby fully heating the water in the lower part of the water tank 1, improving the heat exchange efficiency, and thereby improving the performance and life of the condenser.

[0041] After the heat pump water heater is started, the controller starts the stratified heating mode in response to the stratified heating instruction. It can be understood that according to the preset control strategy, the stratified heating mode is started at the same time as the heat pump water heater is started; or, the stratified heating mode is started according to the stratified heating instruction input by the user.

[0042] Reference Figure 5 ,in Figure 5 This is a flow chart of a control method for a heat pump water heater according to an embodiment of the present invention. Optionally, the stratified heating mode includes obtaining the water temperature of the first heating zone and the water temperature of the second heating zone, and a controller controlling the opening of the regulating valve 311 and the opening and closing of the on-off valve 321 based on the temperature difference between the water temperatures in the first heating zone and the second heating zone.

[0043] Through the above settings, the controller controls the opening of the regulating valve 311 and the opening and closing of the switch valve 321 according to the water temperature of the first heating area and the second heating area, and can make real-time adjustments according to the temperature to further improve the operating efficiency of the heat pump water heater.

[0044] In a specific implementation, the controller adjusts the working state of the switch valve 321 and the regulating valve 311 according to the water temperature feedback from the temperature detection device. Figure 2 and Figure 3 A first temperature measuring device 11 for measuring the water temperature T1 of the first heating area is provided in the first heating area, and a second temperature measuring device 12 for measuring the water temperature T2 of the second heating area is provided in the second heating area. The first temperature measuring device 11 and the second temperature measuring device 12 are both communicatively connected to the controller; the controller controls the opening and closing of the switch valve 321 and the opening degree of the regulating valve 311 in response to the first difference between the temperature difference measured by the first temperature measuring device 11 and the second temperature measuring device 12 and the first preset temperature t0.

[0045] That is, the controller controls the opening and closing of the switch valve 321 and the opening degree of the regulating valve 311 according to the relationship between the difference between the water temperature T1 and the water temperature T2 in the first heating area and the first preset temperature t0.

[0046] Through the above settings, the first difference can be used to determine the water temperature difference between the first heating area and the second heating area of the water tank 1, and then adjust the opening and closing of the switch valve 321 and the opening of the regulating valve 311, so that the operating state of the entire system of the heat pump water heater is optimized to improve the system efficiency.

[0047] Specifically, when the difference between the water temperature T1 in the first heating area and the water temperature T2 in the second heating area is greater than the first preset temperature t0, the controller controls the opening of the regulating valve 311 to decrease to 0-5B and controls the on-off valve 321 to open, so that most of the refrigerant in the refrigerant main pipe 30 enters the second condenser 22 to heat the water in the second heating area. In other words, when T1-T2>t0, the controller controls the opening of the regulating valve 311 to decrease to 0-5B and controls the on-off valve 321 to open. In other words, the temperature difference between the first heating area and the second heating area exceeds the first preset temperature t0, and the heat pump water heater is controlled to heat the second heating area, thereby achieving stratified heating and improving heat exchange efficiency.

[0048] After the heat pump water heater is started, the controller activates the full-tank heating mode in response to the full-tank heating command. According to the full-tank heating mode, the opening of the regulating valve 311 is increased and the on-off valve 321 is adjusted from an open state to a closed state. In the full-tank heating mode, the opening of the regulating valve 311 can be adjusted to its maximum value. This means that, according to a preset control strategy, the full-tank heating mode is activated simultaneously with the start-up of the heat pump water heater; alternatively, the full-tank heating mode is activated in response to a full-tank heating command input by the user.

[0049] Optionally, the full tank heating mode includes: obtaining the water temperature of the first heating area and the water temperature of the second heating area, and the controller controls the opening of the regulating valve 311 and the opening and closing of the switch valve 321 according to the temperature difference between the water temperature of the first heating area and the water temperature of the second heating area.

[0050] Through the above settings, the controller controls the opening of the regulating valve 311 and the opening and closing of the switch valve 321 according to the water temperature of the first heating area and the second heating area, and can make real-time adjustments according to the temperature to further improve the operating efficiency of the heat pump water heater.

[0051] In a specific implementation, the controller adjusts the working state of the switch valve 321 and the regulating valve 311 according to the water temperature feedback from the temperature detection device. Figure 2 and Figure 3 A first temperature measuring device 11 for measuring the water temperature T1 of the first heating area is provided in the first heating area, and a second temperature measuring device 12 for measuring the water temperature T2 of the second heating area is provided in the second heating area. The first temperature measuring device 11 and the second temperature measuring device 12 are both communicatively connected to the controller; the controller controls the opening and closing of the switch valve 321 and the opening degree of the regulating valve 311 in response to the first difference between the temperature difference measured by the first temperature measuring device 11 and the second temperature measuring device 12 and the first preset temperature t0.

[0052] That is, the controller controls the opening and closing of the switch valve 321 and the opening degree of the regulating valve 311 according to the relationship between the difference between the water temperature T1 and the water temperature T2 in the first heating area and the first preset temperature t0.

[0053] Through the above settings, the first difference can be used to determine the water temperature difference between the first heating area and the second heating area of the water tank 1, and then adjust the opening and closing of the switch valve 321 and the opening of the regulating valve 311, so that the operating state of the entire system of the heat pump water heater is optimized to improve the system efficiency.

[0054] Specifically, when the difference between the water temperature T1 in the first heating area and the water temperature T2 in the second heating area is less than or equal to the first preset temperature t0, the controller controls the opening of the regulating valve 311 to be increased and controls the switch valve 321 to be adjusted from an open state to a closed state, so that the refrigerant in the refrigerant main pipe 30 first enters the first condenser 21 and then enters the second condenser 22 through the first refrigerant branch pipe 31, heating the water in the first heating area and the second heating area respectively, that is, fully heating the water tank 1. In other words, when T1-T2≤t0, the controller controls the opening of the regulating valve 311 to be increased and controls the switch valve 321 to be adjusted from an open state to a closed state. In other words, when the difference between the water temperature in the first heating area and the water temperature in the second heating area is less than or equal to the first preset temperature t0, the heat pump water heater is controlled to fully heat the water tank, thereby achieving full tank heating and improving heat exchange efficiency.

[0055] It is understood that the first preset temperature t0 can be set in the control program according to actual conditions. For example, the first preset temperature t0 is 10°C. That is, when the temperature difference between the water in the first heating area and the water in the second heating area exceeds 10°C, the heat pump water heater is controlled to perform stratified heating. When the temperature difference between the water in the first heating area and the water in the second heating area is less than or equal to 10°C, the heat pump water heater is controlled to perform full tank heating. This improves the heat exchange efficiency of the condenser and the operating efficiency of the heat pump water heater.

[0056] It should be noted that when the heat pump water heater is turned on, the controller initiates the stratified heating mode in response to the stratified heating instruction and the full tank heating mode in response to the full tank heating instruction, regardless of the order. That is, the controller can initiate the full tank heating mode first, or the stratified heating mode first. When the controller initiates the full tank heating mode first, the control valve 311 is opened wider and the on-off valve 321 is kept closed. When the controller initiates the stratified heating mode, the control valve 311 is opened to a value between 20° and 30°, and the on-off valve 321 is opened from a closed state.

[0057] In a specific implementation, the height range of the first condenser 21 and the second condenser 22 covering the water tank 1 is 2 / 3 to 4 / 5 of the height of the middle barrel 10 of the water tank 1 .

[0058] First, the water tank 1 of the heat pump water heater includes a middle barrel 10 and two seals 13 provided at both ends of the middle barrel 10. The middle barrel 10 is a barrel-shaped structure with both ends open. The two seals 13 are welded to the two ends of the middle barrel 10, thus forming a closed water storage space. Figure 2 , the height of the middle barrel 10 is H.

[0059] Secondly, in this implementation, the height range of the first condenser 21 and the second condenser 22 covering the water tank 1 is 2 / 3 to 4 / 5 of the height of the middle barrel 10 of the water tank 1, so as to avoid the heat exchange area of the first condenser 21 and the second condenser 22 being too small and affecting the heat exchange efficiency, and to avoid the heat exchange area of the first condenser 21 and the second condenser 22 being too large, resulting in high cost and inconvenient installation.

[0060] In some examples, the height H2 of the second condenser 22 is ½ the height H of the middle tub 10 of the water tank 1 . That is, the second condenser 22 covers half the height of the middle tub 10 , thereby fully heating the water in the second heating area and providing sufficient reserve hot water. It is understood that the weld area between the middle tub 10 and the head 13 is not convenient for installing the condenser 22 . Optionally, the second condenser 22 is positioned a predetermined distance from the bottom of the middle tub 10 to avoid the weld area. This predetermined distance may be 20 mm.

[0061] In some examples, the height H1 of the first condenser 21 is 1 / 3 to 1 / 2 of the height H2 of the second condenser 22 , and a preset interval H0 is defined between the first condenser 21 and the second condenser 22 .

[0062] In actual application, the height H1 of the first condenser 21 can be converted based on the water consumption of at least one person. For example, the height of the first heating area is calculated based on the volume of 60L of 40°C hot water for one person, and then the height H1 of the first condenser 21 is obtained.

[0063] It can be understood that the sum of the height H1 of the first condenser 21 , the height H2 of the second condenser 22 and the preset interval H0 is the height of the first condenser 21 and the second condenser 22 covering the water tank 1 .

[0064] Through the above arrangement, the first condenser 21 and the second condenser 22 have different height ranges, and the height H1 of the first condenser 21 is smaller than the height H2 of the second condenser 22. In other words, the water volume in the first heating area is smaller than the water volume in the second heating area. This not only reduces the amount of water required for rapid heating, achieving rapid heating, but also allows the large amount of water at the bottom of the water tank 1 to be heated to provide sufficient reserve hot water. Furthermore, a predetermined distance H0 is provided between the first condenser 21 and the second condenser 22 to prevent mutual interference between the first and second condensers 21, 22, which could affect heat exchange efficiency.

[0065] In one possible implementation, referring to Figure 3The first temperature measuring device 11 is installed at a first position of the water tank 1, and the first position is within a range of 1 / 3 to 2 / 5 of the height H1 of the first condenser 21. In other words, the first temperature measuring device 11 is installed outside the water tank 1 and is located between 1 / 3 and 2 / 5 of the height H1 of the first condenser 21. In other words, the first temperature measuring device 11 is installed within a range of 1 / 3 to 2 / 5 of the height H1 of the first condenser 21 from its lower end.

[0066] Since the refrigerant flows from the upper end to the lower end of the first condenser 21, the water temperature in the first heating area tends to gradually decrease from its upper end to the lower end. By such an arrangement, the first temperature measuring device 11 is located in the lower half of the first condenser 21, thereby characterizing the water temperature in the first heating area and improving the accuracy of water temperature measurement in the first heating area.

[0067] In one possible implementation, the second temperature measuring device 12 is installed at a second position on the water tank 1, and the second position is located between 1 / 2 and 2 / 3 of the height H2 of the second condenser 21. In other words, the second temperature measuring device 12 is installed outside the water tank 1 and is located between 1 / 2 and 2 / 3 of the height H2 of the second condenser 22. In other words, the second temperature measuring device 12 is installed between 1 / 2 and 2 / 3 of the height H2 of the second condenser 22, from its lower end.

[0068] By such arrangement, the second temperature measuring device 12 is located at the working part of the second condenser 22, thereby representing the water temperature in the second heating area, thereby improving the accuracy of temperature measurement in the second heating area.

[0069] In one possible implementation, the controller is further configured to control the switch valve 321 to be adjusted from an open state to a closed state and the regulating valve 311 to be opened to a larger degree in the rapid heating mode.

[0070] Specifically, the controller also starts the rapid heating mode in response to the rapid heating instruction, controls the opening of the regulating valve 311 to be increased according to the rapid heating mode, and adjusts the switch valve 321 from an open state to a closed state.

[0071] The controller starts the rapid heating mode in response to the rapid heating instruction. It can be understood that according to the preset control strategy, the rapid heating mode is started at the same time as the heat pump water heater is started; or, when the user urgently needs to use hot water, the rapid heating mode is started according to the rapid heating instruction input by the user.

[0072] For example, combined with Figure 5The heat pump water heater is currently in full-tank heating mode, with on-off valve 321 closed and regulating valve 311 at its maximum opening. When the heat pump water heater receives a rapid heating command, it activates rapid heating mode. The controller controls on-off valve 321 to remain closed and regulates regulating valve 311 to a preset opening, or controls the opening of regulating valve 311 based on the temperature feedback from the temperature detection device.

[0073] For example, combining Figure 5 The heat pump water heater is currently in stratified heating mode, with the on-off valve 321 open and the regulating valve 311 adjusted to a 20-30B opening. When the heat pump water heater receives a rapid heating command, the rapid heating mode is activated. The controller controls the on-off valve 321 to close from an open state and adjusts the opening of the regulating valve 311 to a preset opening, or controls the opening of the regulating valve 311 based on the temperature feedback from the temperature detection device.

[0074] For another example, when the heat pump water heater is turned on, the heat pump water heater receives a quick heating instruction and starts the quick heating mode. The controller controls the switch valve 321 to be adjusted from the closed state to the closed state, and controls the opening of the regulating valve 311 to be adjusted to a preset opening, or controls the opening of the regulating valve 311 according to the temperature feedback from the temperature detection device.

[0075] That is to say, in any working state of the heat pump water heater, the rapid heating mode can be started after it receives the rapid heating instruction, and the water in the first heating area can be quickly heated to meet the user's need for rapid water use, thereby improving the user experience.

[0076] In one example, the rapid heating mode includes: obtaining the water temperature T1 of the first heating area and the condensation temperature Tc of the refrigerant outlet of the first condenser 21; the controller controls the opening of the regulating valve 311 and the opening and closing of the switch valve 21 according to the difference between the water temperature T1 of the first heating area and the condensation temperature Tc of the refrigerant outlet of the first condenser 21.

[0077] That is, the controller controls the opening of the regulating valve 311 and the opening and closing of the switch valve 21 according to the relationship between the second difference between the water temperature T1 of the first heating area and the condensation temperature Tc of the refrigerant outlet of the first condenser 21 and the target heat exchange temperature difference Te.

[0078] Through the above settings, the second difference can be used to determine the difference between the water temperature T1 in the first heating area of the water tank 1 and the condensation temperature Tc of the first condenser 21, and then the opening of the regulating valve 311 and the opening and closing of the switch valve 21 can be controlled, so that the water in the first heating area can be quickly heated, thereby improving the heat exchange efficiency of the heat pump water heater.

[0079] Specifically, when the difference between the water temperature T1 in the first heating area and the condensation temperature Tc at the refrigerant outlet of the first condenser is greater than the target heat exchange temperature difference Te, the controller controls the regulating valve 311 to increase the opening, and controls the switch valve 321 to adjust from an open state to a closed state; when the difference between the water temperature T1 in the first heating area and the condensation temperature Tc at the refrigerant outlet of the first condenser is less than or equal to the target heat exchange temperature difference Te, the controller controls the regulating valve 311 to decrease the opening, and controls the switch valve 321 to adjust from an open state to a closed state.

[0080] That is, when Tc - T1 > Te, the controller controls regulating valve 311 to open wider and switches on / off valve 321 from open to closed. When Tc - T1 ≤ Te, the controller controls regulating valve 311 to open narrower and switches on / off valve 321 from open to closed. This accelerates heating of the first heating area, achieving rapid heating. Furthermore, when a user's hot water demand is low, energy waste caused by heating the entire water tank 1 and producing too much hot water is avoided.

[0081] The opening of the regulating valve 311 is controlled according to the following PID control. Specifically, Pi+1 = Pi+ΔP, where Pi+1 is the next step of regulating valve 311, in B units; Pi is the current step of regulating valve 311, in B units; ΔP is the target number of valve regulating steps for regulating valve 311, in B units. Furthermore, ΔP = (Tc-T1)-Δt, where Tc is the condensing temperature at the refrigerant outlet of the first condenser 21, in °C; T1 is the water temperature in the first heating zone, in °C; Δt is the target heat exchange temperature difference, see Table 1, in °C; Te is the ambient temperature, in °C.

[0082] Table 1 Target heat exchange temperature difference Δt

[0083]

[0084] Of course, Table 1 above is merely an example of the target heat exchange temperature difference Δt and is not intended to be limiting. Those skilled in the art may adjust the target heat exchange temperature difference Δt based on actual conditions. Alternatively, those skilled in the art may program the valve 311 to adjust its opening every 60 to 90 seconds based on the temperature.

[0085] Before starting the rapid heating mode, that is, before controlling the opening of the regulating valve to increase according to the rapid heating mode and adjusting the switch valve from the open state to the closed state, it also includes: the controller controls the regulating valve 311 to adjust the opening to 200~400B and maintains the preset time.

[0086] The above arrangement allows the opening of the regulating valve 311 to be approximately within the middle range, making it easier to adjust the opening of the regulating valve 311. Maintaining this opening for a predetermined period of time allows the refrigerant in the heat pump water heater to circulate approximately once within its pipelines. This allows the water temperature in the first heating area and the condensing temperature at the refrigerant outlet of the first condenser 21 to vary over time, thereby improving the accuracy of temperature measurement and, in turn, the heat exchange efficiency of the heat pump water heater.

[0087] In order to measure the condensation temperature of the refrigerant outlet of the first condenser 21, continue to refer to Figure 3 A temperature sensing device 35 for measuring the refrigerant temperature is provided at the outlet of the first condenser 21. The temperature sensing device 35 is in communication with the controller. In response to a second difference between the temperature measured by the temperature sensing device 35 and the first temperature measuring device 11 and the target heat exchange temperature difference, the controller controls all on-off valves 321 to close and the regulating valve 311 to adjust its opening, thereby achieving rapid heating of the first heating area. The temperature sensing device 35 may be a temperature sensor, or other temperature measuring devices known in the art.

[0088] Reference Figures 1 to 4 In some examples, the heat pump water heater further includes a heat exchange device 20, which includes a first manifold 201, a second manifold 202, and a plurality of microchannel flat tubes 203. The first manifold 201 and the second manifold 202 are arranged relative to each other, and both ends of the microchannel flat tubes 203 are connected to the first manifold 201 and the second manifold 202, respectively, and the plurality of microchannel flat tubes 203 are arranged along the length direction of the first manifold 201; a partition plate 204 is respectively arranged in the first manifold 201 and the second manifold 202, and the two partition plates 204 are opposite to each other, the first manifold 201, the second manifold 202, and the microchannel flat tubes 203 above the partition plate 204 form a first condenser 21, and the first manifold 201, the second manifold 202, and the microchannel flat tubes 203 below the partition plate 204 form a second condenser 22.

[0089] Specific reference Figure 2 and Figure 4 The first and second headers 201, 202 of the heat exchange device 20 extend along the height of the water tank 1 and are spaced apart along the circumference of the water tank 1. The ends of a plurality of microchannel flat tubes 203 are connected to the first and second headers 201, 202, respectively, and the plurality of microchannel flat tubes 203 are arranged along the length of the first header 201. Figure 1 and Figure 4 The heat exchange device 20 is shown in an expanded state. Figure 2 and Figure 3 The figure in the middle shows the actual state of the heat exchange device 20 , that is, the microchannel flat tubes 203 are in an arc shape extending circumferentially around the water tank 1 .

[0090] A partition plate 204 is provided within the first manifold 201, dividing the first manifold 201 into two unconnected upper and lower sections. A partition plate 204 is also provided within the second manifold 202, and this partition plate 204 faces the partition plate 204 within the first manifold 201. In other words, the partition plates 204 within the first manifold 201 and the second manifold 202 are at the same height. The partition plate 204 within the second manifold 202 divides the second manifold 202 into two unconnected upper and lower sections.

[0091] Thus, the first manifold 201, the second manifold 202, and the microchannel flat tubes 203 above the two partition plates 204 form the first condenser 21, and the first manifold 201, the second manifold 202, and the microchannel flat tubes 203 below the two partition plates 204 form the second condenser 22. This makes the structures of the first condenser 21 and the second condenser 22 consistent, simplifies the structures of the first condenser 21 and the second condenser 22, facilitates the processing and installation of the first condenser 21 and the second condenser 22, and helps reduce costs. In addition, the height of the first condenser 21 and the second condenser 22 can be set directly by setting the number of microchannel flat tubes 203 above and below the partition plates 204, which facilitates the setting of the height of the first condenser 21 and the second condenser 22, further simplifies the structures of the first condenser 21 and the second condenser 22, and helps reduce costs.

[0092] Continue to refer to Figure 2 and Figure 4 The upper opening of the first header 201 is the refrigerant inlet of the first condenser 21, which is connected to the refrigerant main pipe 30 via the third refrigerant branch pipe 33. The upper opening of the first header 201 near the partition plate 204 is the refrigerant outlet of the first condenser 21, which is connected to the refrigerant inlet of the second condenser 22 via the first refrigerant branch pipe 31. The lower opening of the first header 201 near the partition plate 204 is the refrigerant inlet of the second condenser 22, which is connected to the refrigerant main pipe 30 via the second refrigerant branch pipe 32. The lower opening of the second header 202 is the refrigerant outlet of the second condenser 22, which is connected to the evaporator 4 via the refrigerant return pipe 34.

[0093] By arranging the refrigerant inlet and outlet of the first condenser 21 and the refrigerant inlet of the second condenser 22 on the first manifold 201 , pipeline connection and arrangement are facilitated.

[0094] Continue to refer to Figure 2To ensure that the heat exchange device 20 is wrapped around the outside of the tub 10 in the water tank 1, a gap is provided between the first header 201 and the second header 202. At least one fixed tube 207 is disposed within this gap, with both ends of the fixed tube 207 connected to the first header 201 and the second header 202, respectively. Optionally, multiple fixed tubes 207 are provided, for example, two or three, and the multiple fixed tubes 207 are spaced apart along the height direction of the water tank 1. This improves the stability and reliability of the heat exchange device 20 when installed outside the water tank 1.

[0095] On the basis of the above embodiment, at least one first partition plate 205 is provided in the first collecting pipe 201 and the second collecting pipe 202 above the partition plate 204 to separate the microchannel flat tubes 203 above the partition plate 204 into at least two parts of the refrigerant circulation circuit; at least one second partition plate 206 is provided in the first collecting pipe 201 and the second collecting pipe 202 below the partition plate 203 to separate the microchannel flat tubes 203 below the partition plate 204 into at least two parts of the refrigerant circulation circuit.

[0096] For example, a first partition plate 205 is installed within the first manifold 201 above the partition plate 204, thereby dividing the microchannel flat tubes 203 above the partition plate 204 into at least two interconnected refrigerant circulation loops, thereby increasing the length of the refrigerant circulation loop. In this case, the temperature sensing device 35 can be installed on the first manifold 201 and located at the refrigerant outlet of the first condenser 21. The manifold has a larger diameter than the microchannel flat tubes 203, which facilitates the installation of the temperature sensing device 35. At the refrigerant outlet of the first condenser 21, the refrigerant is in a gas-liquid mixed state, which better represents the condensation temperature at the refrigerant outlet of the first condenser 21.

[0097] For another example, two second partition plates 206 are spaced apart in the first manifold 201 below the partition plate 204, and two second partition plates 206 are spaced apart in the second manifold 202 below the partition plate 204. The second partition plates 206 in the first manifold 201 and the second manifold 202 are staggered up and down, so that the microchannel flat tubes 203 below the partition plate 204 are divided into five connected refrigerant circulation circuits. At this time, the refrigerant circulates along an S-shape, which can increase the contact path length between the refrigerant and the water tank 1 and improve the heat exchange efficiency.

[0098] Of course, the number of the first partition plates 205 and the second partition plates 206 is not limited thereto, and those skilled in the art can set them according to actual conditions.

[0099] Continue to refer to Figure 5 , the control method of the heat pump water heater of the present invention is exemplified below.

[0100] The heat pump water heater is started, at which time the switch valve 321 is in a closed state.

[0101] The controller starts the stratified heating mode in response to the stratified heating instruction, reduces the opening of the stratified heating mode control regulating valve 311 to 20-30B, and controls the switch valve 321 to open, so as to achieve stratified heating of the water in the water tank 1.

[0102] In an optional implementation, the controller obtains the water temperature of the first heating area and the water temperature of the second heating area, and controls the opening of the regulating valve 311 and the opening and closing of the switch valve 321 according to the temperature difference between the water temperature of the first heating area and the water temperature of the second heating area.

[0103] Specifically, when the difference between the water temperature T1 in the first heating area and the water temperature T2 in the second heating area is greater than the first preset temperature t0, the controller controls the opening of the regulating valve 311 to decrease to 20~30B, and controls the switch valve 321 to open, so that most of the refrigerant in the refrigerant main pipe 30 enters the second condenser 22 to heat the water in the second heating area.

[0104] When the difference between the water temperature T1 in the first heating area and the water temperature T2 in the second heating area is less than or equal to the first preset temperature t0, the controller controls the opening of the regulating valve 311 to be increased, and controls the switch valve 321 to be adjusted from an open state to a closed state, so that the refrigerant in the refrigerant main pipe 30 first enters the first condenser 21, and then enters the second condenser 22 through the first refrigerant branch pipe 31, heating the water in the first heating area and the second heating area respectively, that is, the water tank 1 is fully heated. At this time, the heat pump water heater is in a full-tank heating mode.

[0105] Whether the heat pump water heater is in stratified heating mode or full tank heating mode, the controller also responds to the rapid heating instruction to start the rapid heating mode, controls the opening of the regulating valve 311 to be increased according to the rapid heating mode, and adjusts the state of the switch valve 321 to the closed state, quickly heating the water in the upper part of the water tank 1 to meet the user's need for quick use of hot water.

[0106] To sum up, the heat pump water heater provided by the present invention includes a water tank 1, an evaporator 4, a compressor 5, a first condenser 21, a second condenser 22 and a controller. The water tank 1 is divided into a first heating area and a second heating area along the height direction, and the first condenser 21 is covered on the outside of the first heating area, and the second condenser 22 is covered on the outside of the second heating area; the refrigerant inlet of the first condenser 21 is connected to the refrigerant outlet of the compressor 5, and the refrigerant outlet of the first condenser 21 is connected to the refrigerant inlet of the second condenser 22 through the first refrigerant branch 31; and the refrigerant inlet of the second condenser 22 is also connected to the refrigerant outlet of the compressor 5 through the second refrigerant branch 32, and the refrigerant outlet of the second condenser 22 is connected to the refrigerant inlet of the evaporator 4. A regulating valve 311 is installed on the first refrigerant branch 31, and an on-off valve 321 is installed on the second refrigerant branch 32. A controller is in communication with on-off valve 321 and regulating valve 311, respectively, to control the opening of on-off valve 321 and the reduction of the opening of regulating valve 311 to 20-30 degrees in stratified heating mode. This arrangement heats only the second heating zone in stratified heating mode, improving heat exchange efficiency and, in turn, enhancing the performance and lifespan of the condenser.

[0107] Thus far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art may make equivalent changes or substitutions to the relevant technical features, and the technical solutions after such changes or substitutions will fall within the scope of protection of the present invention.

Claims

1. A control method for a heat pump water heater, characterized in that: The heat pump water heater includes: a water tank, an evaporator, a compressor, a first condenser, a second condenser and a controller; the water tank is divided into a first heating area and a second heating area along the height direction, and the first condenser is covered on the outside of the first heating area, and the second condenser is covered on the outside of the second heating area; the refrigerant inlet of the first condenser is connected to the refrigerant outlet of the compressor, and the refrigerant outlet of the first condenser is connected to the refrigerant inlet of the second condenser through a first refrigerant branch pipe; and the refrigerant inlet of the second condenser is also connected to the refrigerant outlet of the evaporator through a second refrigerant branch pipe, and the refrigerant outlet of the second condenser is connected to the refrigerant inlet of the evaporator; a regulating valve is installed on the first refrigerant branch pipe, and an on-off valve is installed on the second refrigerant branch pipe, and the controller is communicatively connected to the on-off valve and the regulating valve respectively; the height of the first condenser is 1 / 3 to 1 / 2 of the height of the second condenser; The control method includes: The controller starts the stratified heating mode in response to the stratified heating instruction, controls the opening of the regulating valve to be reduced to 20~30B according to the stratified heating mode, and opens the switch valve; wherein, the stratified heating mode includes: obtaining the water temperature of the first heating area and the water temperature of the second heating area; the controller controls the opening of the regulating valve and the opening and closing of the switch valve according to the temperature difference between the water temperature of the first heating area and the water temperature of the second heating area.

2. The control method according to claim 1, characterized in that: When the temperature difference between the water temperature in the first heating area and the water temperature in the second heating area is greater than a first preset temperature, the controller controls the opening of the regulating valve to decrease to 20-30B, and the switch valve to open.

3. The control method according to claim 1 or 2, characterized in that: The controller also starts a rapid heating mode in response to a rapid heating instruction, controls the opening of the regulating valve to increase according to the rapid heating mode, and adjusts the switch valve from an open state to a closed state.

4. The control method according to claim 3, characterized in that: The rapid heating mode includes: Acquire the water temperature of the first heating area and the condensation temperature of the refrigerant outlet of the first condenser; The controller controls the opening of the regulating valve and the opening and closing of the switch valve according to the difference between the water temperature of the first heating area and the condensation temperature of the refrigerant outlet of the first condenser.

5. The control method according to claim 4, characterized in that: When the difference between the water temperature of the first heating area and the condensing temperature of the refrigerant outlet of the first condenser is greater than the target heat exchange temperature difference, the controller controls the regulating valve to increase its opening and controls the switch valve to adjust from an open state to a closed state; When the difference between the water temperature of the first heating area and the condensing temperature of the refrigerant outlet of the first condenser is less than or equal to the target heat exchange temperature difference, the controller controls the regulating valve to reduce the opening degree and controls the switch valve to adjust from an open state to a closed state.

6. The control method according to claim 3, characterized in that: Before controlling the opening of the regulating valve to increase according to the rapid heating mode and adjusting the switch valve from an open state to a closed state, the method further includes: The controller controls the regulating valve to adjust the opening to 200-400B and maintain the opening for a preset time.

7. The control method according to claim 2, characterized in that: The controller also starts the full-tank heating mode in response to the full-tank heating instruction, controls the opening of the regulating valve to increase according to the full-tank heating mode, and adjusts the switch valve from an open state to a closed state.

8. The control method according to claim 7, characterized in that: The whole gallbladder heating mode includes: Acquire the water temperature of the first heating area and the water temperature of the second heating area; The controller controls the opening of the regulating valve and the opening and closing of the switch valve according to the temperature difference between the water temperature of the first heating area and the water temperature of the second heating area.

9. The control method according to claim 8, characterized in that: When the temperature difference between the water temperature in the first heating area and the water temperature in the second heating area is less than or equal to a first preset temperature, the controller controls the opening of the regulating valve to increase, and controls the switch valve to adjust from an open state to a closed state.

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