Heat pump water heater control method and heat pump water heater

Abstract

The invention relates to the technical field of hot water supply equipment, and discloses a heat pump water heater control method and a heat pump water heater. Based on the reference environment temperature, the reference water tank temperature is determined from the water tank temperatures detected by a plurality of temperature sensors; if the reference water tank temperature is smaller than the set temperature, the target superheat degree is determined based on the magnitude relation between the reference water tank temperature and a reference temperature threshold value; and adjusting the opening of the expansion valve based on the target superheat degree. A plurality of temperature sensors are arranged in a water tank to detect the water temperatures of different water levels, the water temperatures of different water levels are selected as reference values under different reference environment temperatures, the environment temperature change is predicted in advance to adjust the selected reference water tank temperature in advance, and it is ensured that the heating capacity of a heat pump is matched with the hot water demand of a user; the target superheat degree is determined according to the size relation between the reference water tank temperature and the water tank temperature threshold value, and the opening degree of the expansion valve is adjusted, so that the heating speed of the heat pump is adjusted according to different reference water tank temperatures in the heating process, the heating time is shortened, and the user experience is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of hot water supply equipment, and in particular to a heat pump water heater control method and a heat pump water heater. Background Art

[0002] During the use of the heat pump water heater, as the hot water in the water tank is released, cold water will enter the water tank to replenish the water in the water tank, and the water tank temperature will show stratification with inconsistent upper and lower temperatures. Therefore, the amount of hot water available in the water tank has a certain relationship with the position setting of the temperature sensor.

[0003] Existing water tanks are generally equipped with only one temperature sensor to detect water temperature, while the heating capacity of heat pumps is related to the ambient temperature, and the actual water demand of users will change accordingly under different ambient temperatures. If the heat pump water heater is still controlled according to the water temperature detected by the same temperature sensor under different ambient temperatures, the heat pump heating capacity will not match the actual water demand of users. If multiple temperature sensors are used to detect the water temperature of the water tank, how to control the operation of the heat pump water heater is an urgent problem to be solved. Therefore, there is still room for improvement. Summary of the invention

[0004] The first technical problem solved by the present invention is to provide a heat pump water heater control method, which effectively solves the problem that the current adjustment of the water tank temperature cannot meet the actual hot water demand and the water heater usage experience is poor.

[0005] The second technical problem solved by the present invention is to provide a heat pump water heater, which effectively solves the problem that the current adjustment of the water tank temperature cannot meet the actual hot water demand and the water heater has a poor user experience.

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

[0007] A control method for a heat pump water heater, wherein a plurality of temperature sensors are arranged in a water tank of the heat pump water heater, and the plurality of temperature sensors are arranged in sequence and at intervals along a height direction of the water tank; the method comprises:

[0008] Based on the reference ambient temperature, determining a reference water tank temperature from the water tank temperatures detected by a plurality of temperature sensors; the reference ambient temperature is determined based on at least one period of historical ambient temperature and / or predicted ambient temperature;

[0009] If the reference water tank temperature is lower than the set temperature, the target superheat is determined based on the magnitude relationship between the reference water tank temperature and the corresponding water tank temperature threshold; the water tank temperature threshold is lower than the set temperature;

[0010] Based on the target superheat, the expansion valve opening is adjusted.

[0011] Compared with the background technology, the heat pump water heater control method of the present invention has the following beneficial effects: multiple temperature sensors are arranged in the water tank to respectively detect the water temperatures at different water levels in the water tank, and based on the reference ambient temperature, the reference water tank temperature is determined from the water tank temperatures detected by the multiple temperature sensors, so that the water temperatures at different water levels can be selected as reference values ​​under different reference ambient temperatures, and since the reference ambient temperature is determined based on at least one period of historical ambient temperature and / or predicted ambient temperature, the ambient temperature change can be predicted in advance to adjust the selected reference water tank temperature in advance to ensure that the heating amount of the heat pump matches the user's hot water demand; and when the reference water tank temperature is lower than the set temperature, the target superheat is determined according to the relationship between the selected reference water tank temperature and the corresponding water tank temperature threshold, and the expansion valve opening is adjusted accordingly, so that during the heating process, the heat pump heating speed can be adjusted according to the different reference water tank temperatures, thereby shortening the heating time and improving the user experience.

[0012] In one embodiment, determining a reference water tank temperature from water tank temperatures detected by a plurality of temperature sensors based on a reference ambient temperature comprises:

[0013] If the reference ambient temperature is greater than the first ambient temperature, the reference water tank temperature is determined to be the first reference water tank temperature, and the first reference water tank temperature is the water tank temperature corresponding to the first water level;

[0014] If the reference ambient temperature is between the second ambient temperature and the first ambient temperature, the reference water tank temperature is determined to be the second reference water tank temperature, and the second reference water tank temperature is the water tank temperature corresponding to the second water level; the first water level is higher than the second water level; and the second ambient temperature is lower than the first ambient temperature;

[0015] If the reference ambient temperature is lower than the second ambient temperature, the reference water tank temperature is determined to be the third reference water tank temperature, and the third reference water tank temperature is the water tank temperature corresponding to the third water level; the second water level is higher than the third water level.

[0016] In one embodiment, if the reference water tank temperature is the first reference water tank temperature, determining the target superheat degree based on the magnitude relationship between the reference water tank temperature and the corresponding water tank temperature threshold includes:

[0017] If the first reference water tank temperature is less than the water tank temperature threshold, determining the target superheat degree to be the first superheat degree;

[0018] If the first reference water tank temperature is greater than or equal to the water tank temperature threshold, the target superheat is determined to be a second superheat; and the second superheat is greater than the first superheat.

[0019] In one embodiment, if the reference water tank temperature is the second reference water tank temperature, determining the target superheat degree based on the magnitude relationship between the reference water tank temperature and the corresponding water tank temperature threshold includes:

[0020] Obtain a reference water tank temperature difference; the reference water tank temperature difference is the difference between the maximum water tank temperature and the minimum water tank temperature among the water tank temperatures detected by multiple temperature sensors;

[0021] If the second reference water tank temperature is less than the water tank temperature threshold, then comparing the reference water tank temperature difference with the first temperature difference threshold;

[0022] If the reference water tank temperature difference is less than the first temperature difference threshold, determining the target superheat degree to be the first superheat degree;

[0023] If the reference water tank temperature difference is greater than the first temperature difference threshold, the target superheat is determined to be a second superheat; and the second superheat is greater than the first superheat.

[0024] In one embodiment, after obtaining the reference water tank temperature difference, the method further includes:

[0025] If the second reference water tank temperature is greater than the water tank temperature threshold, the reference water tank temperature difference is compared with the second temperature difference threshold; the second temperature difference threshold is greater than the first temperature difference threshold;

[0026] If the reference water tank temperature difference is less than the second temperature difference threshold, determining the target superheat degree to be the second superheat degree;

[0027] If the reference water tank temperature difference is greater than the second temperature difference threshold, the target superheat is determined to be the third superheat; and the third superheat is greater than the second superheat.

[0028] In one embodiment, if the reference water tank temperature is a third reference water tank temperature, determining the target superheat degree based on a magnitude relationship between the reference water tank temperature and a corresponding water tank temperature threshold includes:

[0029] Obtain a reference water tank temperature difference; the reference water tank temperature difference is the difference between the maximum water tank temperature and the minimum water tank temperature among the water tank temperatures detected by multiple temperature sensors;

[0030] If the third reference water tank temperature is less than the water tank temperature threshold, then comparing the reference water tank temperature difference with the first temperature difference threshold;

[0031] If the reference water tank temperature difference is less than the first temperature difference threshold, determining the target superheat degree to be the first superheat degree;

[0032] If the reference water tank temperature difference is greater than the first temperature difference threshold, the target superheat is determined to be a second superheat; and the second superheat is greater than the first superheat.

[0033] In one embodiment, after obtaining the reference water tank temperature difference, the method further includes:

[0034] If the third reference water tank temperature is greater than the water tank temperature threshold, the reference water tank temperature difference is compared with the second temperature difference threshold; the second temperature difference threshold is greater than the first temperature difference threshold;

[0035] If the reference water tank temperature difference is less than the second temperature difference threshold, determining the target superheat degree to be the first superheat degree;

[0036] If the reference water tank temperature difference is greater than the second temperature difference threshold, the target superheat is determined to be the third superheat; and the third superheat is greater than the first superheat.

[0037] In one embodiment, the method further comprises:

[0038] If the reference water tank temperature difference is greater than the first temperature difference threshold, or the reference water tank temperature difference is greater than the second temperature difference threshold, the fan speed of the water heater is increased.

[0039] In one embodiment, adjusting the expansion valve opening based on the target superheat includes:

[0040] If the current superheat is greater than the target superheat, the expansion valve opening is increased.

[0041] If the current superheat is less than the target superheat, the expansion valve opening is reduced.

[0042] The above second technical problem is solved by the following technical solution:

[0043] A heat pump water heater comprises a water tank, a plurality of temperature sensors, and a controller;

[0044] A plurality of temperature sensors are arranged in sequence and at intervals along the height direction of the water tank, and the temperature sensors are electrically connected to the controller;

[0045] The controller is used to execute the water heater control method as described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0047] Figure 1 is a flow chart of a heat pump water heater control method according to an embodiment of the present invention;

[0048] Figure 2 is a schematic diagram of a water tank temperature in a heat pump water heater control method according to an embodiment of the present invention;

[0049] Figure 3 It is a schematic flow chart of determining a target superheat when the reference water tank temperature is a first reference water tank temperature in a heat pump water heater control method according to an embodiment of the present invention;

[0050] Figure 4 It is a flow chart of determining a target superheat when the reference water tank temperature is a second reference water tank temperature in a heat pump water heater control method according to an embodiment of the present invention;

[0051] Figure 5 It is a flow chart of determining a target superheat when the reference water tank temperature is a second reference water tank temperature in a heat pump water heater control method according to an embodiment of the present invention;

[0052] Figure 6 It is a flow chart of determining a target superheat when the reference water tank temperature is a third reference water tank temperature in a heat pump water heater control method according to an embodiment of the present invention;

[0053] Figure 7 It is a flow chart of determining a target superheat when the reference water tank temperature is a third reference water tank temperature in a heat pump water heater control method according to an embodiment of the present invention. DETAILED DESCRIPTION

[0054] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0055] In the description of this application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the feature. In the description of this application, unless otherwise specified, "plurality" means two or more.

[0056] The water tank of a heat pump water heater is generally only equipped with one temperature sensor to detect the water temperature. The heating capacity of the heat pump is related to the ambient temperature, and the user's actual water demand will change accordingly under different ambient temperatures. If the heat pump water heater is still controlled based on the water temperature detected by the same temperature sensor under different ambient temperatures, the heat pump heating capacity will not match the user's actual water demand.

[0057] Based on this, an embodiment of the present invention provides a heat pump water heater control method, in which multiple temperature sensors are arranged in the water tank to respectively detect the water temperature at different water levels in the water tank, and based on the reference ambient temperature, the reference water tank temperature is determined from the water tank temperatures detected by the multiple temperature sensors, so that the water temperatures at different water levels can be selected as reference values ​​at different reference ambient temperatures, and because the reference ambient temperature is determined based on at least one period of historical ambient temperature and / or predicted ambient temperature, the ambient temperature change can be predicted in advance to adjust the selected reference water tank temperature in advance, so as to ensure that the heating capacity of the heat pump matches the user's hot water demand. At the same time, when the reference water tank temperature is lower than the set temperature, the target superheat is determined according to the size relationship between the selected reference water tank temperature and the corresponding water tank temperature threshold, and the expansion valve opening is adjusted accordingly, so that the heat pump heating speed can be adjusted according to the different reference water tank temperatures during the heating process, thereby shortening the heating time and improving the user experience.

[0058] Combine the following Figures 1 to 7 , describing an embodiment of the present invention.

[0059] According to an embodiment of the present invention, on the one hand, a heat pump water heater control method is provided, and the method is applied to a heat pump water heater; wherein a plurality of temperature sensors are provided in a water tank of the heat pump water heater, and the plurality of temperature sensors are arranged in sequence and at intervals along the height direction of the water tank, and the plurality of temperature sensors correspond to different water levels of the water tank respectively; the number and position of the temperature sensors can be adjusted according to specific needs in actual applications, and no specific restrictions are made here. Figure 1 is a flow chart of a heat pump water heater control method according to an embodiment of the present invention, such as Figure 1 As shown, the method includes:

[0060] Step 110: Based on the reference ambient temperature, determine a reference water tank temperature from the water tank temperatures detected by a plurality of temperature sensors.

[0061] In the embodiment of the present invention, the reference ambient temperature is an ambient temperature obtained by predicting and estimating the current ambient temperature. The reference ambient temperature is determined based on at least one period of historical ambient temperature and / or predicted ambient temperature; wherein the historical ambient temperature refers to the ambient temperature that has been detected, and the predicted ambient temperature refers to the ambient temperature obtained based on weather forecasting methods such as weather forecasts; the period refers to the control period of the water heater, and within a control period, the same reference water tank temperature and the same control logic are used to control the water heater.

[0062] In one embodiment, the control cycle of the water heater can be set according to the user's region, the climate environment of the region, and the user's own needs; for example, the control cycle can be set to one day, and the reference ambient temperature is determined every day based on the historical ambient temperature, that is, the ambient temperature detected in the past few days, and the predicted ambient temperature, that is, the ambient temperature obtained through weather forecasting methods such as weather forecasts. For example, for areas with large temperature differences, one day can be divided into multiple control cycles according to the daily temperature change trend, and different reference ambient temperatures are used in each of the multiple control cycles.

[0063] In one embodiment, if the reference ambient temperature is determined only based on the historical ambient temperature or the predicted ambient temperature, the historical ambient temperature or the predicted ambient temperature can be directly used as the reference ambient temperature. If the reliability of the reference ambient temperature is to be improved, the historical ambient temperature and the predicted ambient temperature can be combined, and an ambient temperature prediction model can be established for the historical ambient temperature. The historical ambient temperature is input into the ambient temperature prediction model to obtain the ambient temperature predicted based on the historical ambient temperature, and then the ambient temperature is compared with the predicted ambient temperature, and corresponding data processing is performed, such as taking the average value, to obtain the final reference ambient temperature.

[0064] In the embodiment of the present invention, the user's hot water demand is different under different ambient temperatures. Specifically, if the ambient temperature is high, the user's hot water demand is relatively low; if the ambient temperature is low, the user's hot water demand is relatively high. At the same time, the cold water in the water tank enters from the bottom of the water tank, so the water tank temperature at the top of the water tank will be relatively higher than the water tank temperature at the bottom of the water tank. If it is determined that the user's hot water demand is low, the heat required for heating the water in the water tank is relatively low, so the water tank temperature at the top of the water tank can be determined as the reference water tank temperature. If it is determined that the user's hot water demand is high, the heat required for heating the water in the water tank is relatively high, and the water tank temperature at the bottom of the water tank can be determined as the reference water tank temperature.

[0065] In the embodiment of the present invention, if the reference ambient temperature is high, the user's hot water demand is relatively low, and the water tank temperature detected by the corresponding temperature sensor with a higher water level can be selected as the reference water tank temperature. If the reference ambient temperature is low, the user's hot water demand is high, and the water tank temperature detected by the corresponding temperature sensor with a lower water level can be selected as the reference water tank temperature.

[0066] Step 120: If the reference water tank temperature is lower than the set temperature, a target superheat degree is determined based on the relationship between the reference water tank temperature and the corresponding water tank temperature threshold.

[0067] In the embodiment of the present invention, the set temperature is the water temperature set by the user, that is, the target water tank temperature of the water heater. If the reference water tank temperature is lower than the set temperature, the current water tank temperature cannot meet the user's needs, indicating that the water in the water tank needs to be heated at this time. Therefore, based on the relationship between the reference water tank temperature and the corresponding water tank temperature threshold, the target superheat is determined, and the expansion valve opening is adjusted based on the target superheat, thereby achieving the adjustment of the water tank temperature. Among them, the water tank temperature threshold is lower than the set temperature.

[0068] Step 130: Based on the target superheat, adjust the opening of the expansion valve.

[0069] In the embodiment of the present invention, the opening of the expansion valve in the heat pump unit is adjusted to adjust the superheat to the target superheat, thereby achieving the adjustment of the water tank temperature.

[0070] In one embodiment, the adjustment method of the expansion valve opening is determined according to the relationship between the current superheat and the target superheat; specifically, if the current superheat is greater than the target superheat, the expansion valve opening is increased; if the current superheat is less than the target superheat, the expansion valve opening is reduced.

[0071] In one embodiment, the reference ambient temperature can be divided into multiple corresponding ambient temperature intervals according to different user hot water demands. Specifically, the reference ambient temperature can be divided into three ambient temperature intervals, namely, the reference ambient temperature is greater than the first ambient temperature, the reference ambient temperature is between the second ambient temperature and the first ambient temperature, and the reference ambient temperature is less than the second ambient temperature; wherein the second ambient temperature is less than the first ambient temperature; it should be noted that the number of ambient temperature intervals obtained by dividing the reference ambient temperature and the temperature range corresponding to the ambient temperature interval can be adjusted according to actual applications, and no specific restrictions are made here. The three ambient temperature intervals adopt different reference water tank temperatures and control strategies, as shown below:

[0072] If the reference ambient temperature is greater than the first ambient temperature, it indicates that the user's hot water demand is low at this time. At this time, the water tank temperature at the top of the water tank can be used as the reference water tank temperature. Therefore, the reference water tank temperature is determined to be the first reference water tank temperature, and the first reference water tank temperature is the water tank temperature corresponding to the first water level. The first water level is a higher water level in the water tank. Generally speaking, the water level higher than the center of the water tank can be used as the first water level.

[0073] If the reference ambient temperature is between the second ambient temperature and the first ambient temperature, the user's demand for hot water increases compared to the ambient temperature interval where the reference ambient temperature is greater than the first ambient temperature. At this time, a water tank temperature corresponding to a water level lower than the first water level can be used as the reference water tank temperature; therefore, the reference water tank temperature is determined to be the second reference water tank temperature, the second reference water tank temperature is the water tank temperature corresponding to the second water level, and the first water level is higher than the second water level. Generally speaking, the water level at the center of the water tank or below the center of the water tank can be used as the second water level.

[0074] If the reference ambient temperature is lower than the second ambient temperature, the user's demand for hot water increases further than when the reference ambient temperature is between the second ambient temperature and the first ambient temperature, and at this time, a water tank temperature corresponding to a water level lower than the second water level can be used as the reference water tank temperature; therefore, the reference water tank temperature is determined to be the third reference water tank temperature, the third reference water tank temperature is the water tank temperature corresponding to the third water level, and the second water level is higher than the third water level. Generally speaking, a water level lower than the center of the water tank can be used as the third water level.

[0075] In a specific embodiment, Figure 2 Schematic diagram of the water tank temperature in a heat pump water heater control method according to an embodiment of the present invention. Figure 2 As shown, there are 6 temperature sensors in the water tank, and the corresponding water levels are from high to low: water tank temperature 1, water tank temperature 2, water tank temperature 3, water tank temperature 4, water tank temperature 5, and water tank temperature 6. Among them, the water level corresponding to water tank temperature 3 is the water level above the center of the water tank, the water level corresponding to water tank temperature 4 is the water level below the center of the water tank, and water tank temperature 5 is a water level lower than the water level corresponding to water tank temperature 4. Therefore, according to Figure 2 According to the settings in , water tank temperature 3 can be used as the first reference water tank temperature, water tank temperature 4 can be used as the second reference water tank temperature, and water tank temperature 5 can be used as the third reference water tank temperature.

[0076] In one embodiment, the above embodiment divides the reference ambient temperature into three ambient temperature intervals to obtain different reference water tank temperatures. Correspondingly, the control strategies corresponding to different ambient temperature intervals and different reference water tank temperatures are also different, which are specifically divided into the following three situations:

[0077] In the first case, if the reference water tank temperature is the first reference water tank temperature, the reference ambient temperature is relatively high and the user's hot water demand is relatively low. Therefore, the energy-saving mode can be used to adjust the expansion valve opening to improve the energy efficiency of the water heater. In the energy-saving mode, the heat pump unit will reach the temperature and shut down relatively quickly. Specifically, Figure 3is a flow chart of determining a target superheat when the reference water tank temperature is a first reference water tank temperature in a heat pump water heater control method according to an embodiment of the present invention, such as Figure 3 As shown, if the reference water tank temperature is the first reference water tank temperature, the above step 130 includes:

[0078] Step 310: If the first reference water tank temperature is less than the water tank temperature threshold, the target superheat degree is determined to be the first superheat degree.

[0079] In an embodiment of the present invention, if the first reference water tank temperature is less than the water tank temperature threshold, it indicates that the current water tank temperature is far away from the set temperature, and therefore the target superheat can be determined as the first superheat; wherein the first superheat can be set to a relatively small superheat to avoid an increase in the temperature difference between the top layer of the water temperature channel and the water tank due to excessively high exhaust temperature, thereby reducing the stratification of the water tank temperature and making the overall water temperature in the water tank more balanced, thereby improving the user experience.

[0080] Step 320: If the first reference water tank temperature is greater than or equal to the water tank temperature threshold, determine the target superheat degree to be the second superheat degree.

[0081] In the embodiment of the present invention, if the first reference water tank temperature is greater than or equal to the water tank temperature threshold, it indicates that the current water tank temperature is close to the set temperature, so the target superheat can be determined as the second superheat, and the second superheat is greater than the first superheat. Compared with the case where the first reference water tank temperature is less than the water tank temperature, a higher superheat is used when the water tank temperature is higher, which can shorten the heating process and improve the overall energy efficiency of the water heater.

[0082] In the second case, if the reference water tank temperature is the second reference water tank temperature, the user's hot water demand increases compared to the case where the reference water tank temperature is the first reference water tank temperature. Therefore, the intelligent mode can be used to adjust the expansion valve opening to increase the heat provided to the water in the water tank to ensure that the water tank temperature can meet the user's needs. Specifically, Figure 4 is a flow chart of determining a target superheat when the reference water tank temperature is the second reference water tank temperature in a heat pump water heater control method according to an embodiment of the present invention, such as Figure 4 As shown, if the reference water tank temperature is the second reference water tank temperature, the above step 130 includes:

[0083] Step 410: Obtain a reference water tank temperature difference.

[0084] In the embodiment of the present invention, the reference water tank temperature difference is the difference between the maximum water tank temperature and the minimum water tank temperature among the water tank temperatures detected by multiple temperature sensors. The reference water tank temperature is used to characterize the water temperature difference in the water tank, thereby reflecting the stratification of the water tank temperature.

[0085] In one embodiment, the temperature sensors are evenly distributed in the water tank, that is, the water tank is divided equally from top to bottom according to the number of temperature sensors, and a temperature sensor is set in the middle of each equal part, so as to ensure that the temperature of each position of the water tank from high to low can be detected, so that the reference water tank temperature difference obtained according to the water tank temperature detected by the temperature sensor can accurately represent the stratification of the water tank temperature.

[0086] Step 420: If the second reference water tank temperature is less than the water tank temperature threshold, the reference water tank temperature difference is compared with the first temperature difference threshold.

[0087] In an embodiment of the present invention, if the second reference water tank temperature is less than the water tank temperature threshold, it indicates that the current water tank temperature is close to the set temperature. Therefore, the temperature difference threshold corresponding to the current reference water tank temperature difference can be determined as the first temperature difference threshold, and the reference water tank temperature difference is compared with the first temperature difference threshold to determine the target superheat based on the size relationship between the reference water tank temperature difference and the first temperature difference threshold, thereby adjusting the opening of the expansion valve.

[0088] Step 430: If the reference water tank temperature difference is less than the first temperature difference threshold, the target superheat degree is determined to be the first superheat degree.

[0089] In an embodiment of the present invention, if the reference water tank temperature difference is less than the first temperature difference threshold, it indicates that the temperature difference between the upper and lower parts of the water tank is relatively small, the amount of cold water entering the water tank is small, and the amount of hot water flowing out of the water tank is also small. It can be determined that the user's current hot water usage is small, so the target superheat can be determined as the first superheat. While heating the water in the water tank, the increase in the temperature difference between the top layer of the water temperature channel and the water tank caused by the exhaust temperature being too high is avoided, thereby reducing the stratification of the water tank temperature and making the overall water temperature in the water tank more balanced, thereby improving the user experience.

[0090] Step 440: If the reference water tank temperature difference is greater than the first temperature difference threshold, the target superheat degree is determined to be the second superheat degree.

[0091] In an embodiment of the present invention, if the reference water tank temperature is greater than the first temperature difference threshold, it indicates that the temperature difference between the upper and lower parts of the water tank is relatively large, the amount of cold water entering the water tank is large, and the amount of hot water flowing out of the water tank is also large. It can be determined that the user's current hot water usage is large, and the user may be using hot water. Therefore, the target superheat can be determined as the second superheat, and the second superheat is greater than the first superheat; thus, by adopting a higher superheat, the temperature difference between the topmost flow path of the water temperature channel and the water tank is increased, thereby quickly heating the hot water at the top of the water tank to ensure that the hot water provided to the user can meet the user's temperature requirements for hot water.

[0092] In one embodiment, when the reference water tank temperature is the second reference water tank temperature, the second reference water tank temperature is still greater than the water tank temperature threshold. At this time, the temperature difference threshold corresponding to the reference water tank temperature difference is also different from the case where the second reference water tank temperature is less than the water tank temperature threshold. Specifically, Figure 5 is a flow chart of determining a target superheat when the reference water tank temperature is the second reference water tank temperature in a heat pump water heater control method according to an embodiment of the present invention, such as Figure 5 As shown, if the reference water tank temperature is the second reference water tank temperature, after the above step 410 obtains the reference water tank temperature difference, it also includes:

[0093] Step 510: If the second reference water tank temperature is greater than the water tank temperature threshold, the reference water tank temperature difference is compared with the second temperature difference threshold.

[0094] In the embodiment of the present invention, if the second reference water tank temperature is greater than the water tank temperature threshold, it indicates that the current water tank temperature is close to the set temperature. Therefore, the temperature difference threshold corresponding to the current reference water tank temperature difference can be determined as the second temperature difference threshold, and the reference water tank temperature difference is compared with the second temperature difference threshold to determine the target superheat according to the size relationship between the reference water tank temperature difference and the second temperature difference threshold, thereby adjusting the opening of the expansion valve. Among them, considering that the stratification of the water tank temperature will be more serious under high water temperature, the temperature difference threshold under low water temperature will be easier to reach under high water temperature, so the second temperature difference threshold is set to be greater than the first temperature difference threshold.

[0095] Step 520: If the reference water tank temperature difference is less than the second temperature difference threshold, the target superheat degree is determined to be the second superheat degree.

[0096] In the embodiment of the present invention, if the reference water tank temperature difference is less than the second temperature difference threshold, it indicates that the temperature difference between the upper and lower parts of the water tank is relatively small, the amount of cold water entering the water tank is small, and the amount of hot water flowing out of the water tank is also small. It can be determined that the user's current hot water usage is small, so the target superheat can be determined as the second superheat. Compared with the case where the second reference water tank temperature is less than the water tank temperature threshold, a higher superheat is used to shorten the heating process, thereby improving the overall energy efficiency of the water heater.

[0097] Step 530: If the reference water tank temperature difference is greater than the second temperature difference threshold, the target superheat degree is determined to be the third superheat degree.

[0098] In the embodiment of the present invention, if the reference water tank temperature difference is greater than the second temperature difference threshold, it indicates that the temperature difference between the upper and lower parts of the water tank is relatively large, the amount of cold water entering the water tank is large, and the amount of hot water flowing out of the water tank is also large. It can be determined that the user's current hot water usage is large, and the user may be using hot water, so the target superheat can be determined as the third superheat. Among them, the third superheat is greater than the second superheat; on the one hand, a higher superheat is used to increase the temperature difference between the topmost flow path of the water temperature channel and the water tank, so as to quickly heat the hot water at the top of the water tank to ensure that the hot water provided to the user can meet the user's temperature requirements for hot water. On the other hand, compared with the case where the second reference water tank temperature is less than the water tank temperature threshold, a higher superheat is used to shorten the heating process, thereby improving the overall energy efficiency of the water heater.

[0099] In the third case, if the reference water tank temperature is the third reference water tank temperature, the user's hot water demand is further increased compared to the case where the reference water tank temperature is the second reference water tank temperature. Therefore, the capacity increase mode can be adopted to adjust the expansion valve opening to further increase the heat provided to the water in the water tank to ensure that the water tank temperature can meet the user's needs. Specifically, Figure 6 is a flow chart of determining a target superheat when the reference water tank temperature is a third reference water tank temperature in a heat pump water heater control method according to an embodiment of the present invention, such as Figure 6 As shown, if the reference water tank temperature is the third reference water tank temperature, the above step 130 includes:

[0100] Step 610: Obtain the reference water tank temperature difference.

[0101] In the embodiment of the present invention, the reference water tank temperature difference is the difference between the maximum water tank temperature and the minimum water tank temperature among the water tank temperatures detected by multiple temperature sensors. The reference water tank temperature is used to characterize the water temperature difference in the water tank, thereby reflecting the stratification of the water tank temperature.

[0102] Step 620: If the third reference water tank temperature is less than the water tank temperature threshold, the reference water tank temperature difference is compared with the first temperature threshold.

[0103] In an embodiment of the present invention, if the third reference water tank temperature is less than the water tank temperature threshold, it indicates that the current water tank temperature is close to the set temperature. Therefore, the temperature difference threshold corresponding to the current reference water tank temperature difference can be determined as the first temperature difference threshold, and the reference water tank temperature difference is compared with the first temperature threshold to determine the target superheat based on the size relationship between the reference water tank temperature difference and the first temperature difference threshold, thereby adjusting the opening of the expansion valve.

[0104] Step 630: If the reference water tank temperature difference is less than the first temperature difference threshold, the target superheat degree is determined to be the first superheat degree.

[0105] In an embodiment of the present invention, if the reference water tank temperature difference is less than the first temperature difference threshold, it indicates that the temperature difference between the upper and lower parts of the water tank is relatively small, the amount of cold water entering the water tank is small, and the amount of hot water flowing out of the water tank is also small. It can be determined that the user's current hot water usage is small, so the target superheat can be determined as the first superheat. While heating the water in the water tank, the increase in the temperature difference between the top layer of the water temperature channel and the water tank caused by the exhaust temperature being too high is avoided, thereby reducing the stratification of the water tank temperature and making the overall water temperature in the water tank more balanced, thereby improving the user experience.

[0106] Step 640: If the reference water tank temperature difference is greater than the first temperature difference threshold, the target superheat degree is determined to be the second superheat degree.

[0107] In an embodiment of the present invention, if the reference water tank temperature is greater than the first temperature difference threshold, it indicates that the temperature difference between the upper and lower parts of the water tank is relatively large, the amount of cold water entering the water tank is large, and the amount of hot water flowing out of the water tank is also large. It can be determined that the user's current hot water usage is large, and the user may be using hot water. Therefore, the target superheat can be determined as the second superheat, and the second superheat is greater than the first superheat; thus, by adopting a higher superheat, the temperature difference between the topmost flow path of the water temperature channel and the water tank is increased, thereby quickly heating the hot water at the top of the water tank to ensure that the hot water provided to the user can meet the user's temperature requirements for hot water.

[0108] In one embodiment, when the reference water tank temperature is the third reference water tank temperature, the third reference water tank temperature is still greater than the water tank temperature threshold. At this time, the temperature difference threshold corresponding to the reference water tank temperature difference is also different from the case where the third reference water tank temperature is less than the water tank temperature threshold. Specifically, Figure 7 is a flow chart of determining a target superheat when the reference water tank temperature is a third reference water tank temperature in a heat pump water heater control method according to an embodiment of the present invention, such as Figure 7 As shown, if the reference water tank temperature is the third reference water tank temperature, after obtaining the reference water tank temperature difference in step 610, the following further includes:

[0109] Step 710: If the third reference water tank temperature is greater than the water tank temperature threshold, the reference water tank temperature difference is compared with the second temperature difference threshold.

[0110] In the embodiment of the present invention, if the third reference water tank temperature is greater than the water tank temperature threshold, it indicates that the current water tank temperature is close to the set temperature. Therefore, the temperature difference threshold corresponding to the current reference water tank temperature difference can be determined as the second temperature difference threshold, and the reference water tank temperature difference is compared with the second temperature difference threshold to determine the target superheat according to the size relationship between the reference water tank temperature difference and the second temperature difference threshold, thereby adjusting the opening of the expansion valve. Among them, considering that the stratification of the water tank temperature will be more serious under high water temperature, the temperature difference threshold under low water temperature will be easier to reach under high water temperature, so the second temperature difference threshold is set to be greater than the first temperature difference threshold.

[0111] Step 720: If the reference water tank temperature difference is less than the second temperature difference threshold, the target superheat degree is determined to be the first superheat degree.

[0112] In the embodiment of the present invention, if the reference water tank temperature difference is less than the second temperature difference threshold, it indicates that the temperature difference between the upper and lower parts of the water tank is relatively small, the amount of cold water entering the water tank is small, and the amount of hot water flowing out of the water tank is also small. It can be determined that the current hot water usage of the user is small, so the target superheat can be determined as the first superheat. Considering that compared with the case where the third reference water tank temperature is less than the water tank temperature threshold, the water tank temperature is higher and the stratification of the water tank is more serious, a lower superheat is used. At the same time, since the water tank temperature is higher than the water tank temperature when the reference water tank temperature is the second reference water tank temperature, the first superheat lower than the second superheat can be used at this time.

[0113] Step 730: If the reference water tank temperature difference is greater than the second temperature difference threshold, the target superheat degree is determined to be the third superheat degree.

[0114] In the embodiment of the present invention, if the reference water tank temperature difference is greater than the second temperature difference threshold, it indicates that the temperature difference between the upper and lower parts of the water tank is relatively large, the amount of cold water entering the water tank is large, and the amount of hot water flowing out of the water tank is also large. It can be determined that the user's current hot water usage is large, and the user may be using hot water, so the target superheat can be determined as the third superheat. Among them, the third superheat is greater than the second superheat; on the one hand, a higher superheat is used to increase the temperature difference between the topmost flow path of the water temperature channel and the water tank, so as to quickly heat the hot water at the top of the water tank to ensure that the hot water provided to the user can meet the user's temperature requirements for hot water. On the other hand, compared with the case where the third reference water tank temperature is less than the water tank temperature threshold, a higher superheat is used to shorten the heating process, thereby improving the overall energy efficiency of the water heater.

[0115] In one embodiment, in order to improve the exchange efficiency and prevent local overheating in the above embodiment, when the exhaust temperature is increased by using a higher superheat to quickly heat the hot water at the top of the water tank, that is, when the reference water tank temperature difference is greater than the first temperature difference threshold and the reference water tank temperature difference is greater than the second temperature difference threshold, the fan speed of the water heater is increased. Specifically, if the reference water tank temperature difference is greater than the first temperature difference threshold, or the reference water tank temperature difference is greater than the second temperature difference threshold, the fan speed of the water heater is increased. In other cases, the fan speed is kept unchanged.

[0116] The heat pump water heater control method provided by the embodiment of the present invention sets a plurality of temperature sensors in the water tank to respectively detect the water temperature of different water levels in the water tank, and determines the reference water tank temperature from the water tank temperatures detected by the plurality of temperature sensors based on the reference ambient temperature, so that the water temperature of different water levels can be selected as the reference value under different reference ambient temperatures, and because the reference ambient temperature is determined based on the historical ambient temperature and / or predicted ambient temperature of at least one cycle, the ambient temperature change can be predicted in advance to adjust the selected reference water tank temperature in advance, so as to ensure that the heating capacity of the heat pump matches the hot water demand of the user. At the same time, when the reference water tank temperature is lower than the set temperature, the target superheat is determined according to the size relationship between the selected reference water tank temperature and the corresponding water tank temperature threshold, and the expansion valve opening is adjusted accordingly, so that the heat pump heating speed can be adjusted according to the different reference water tank temperatures during the heating process, so as to shorten the heating time and improve the user experience.

[0117] According to an embodiment of the present invention, on the other hand, a heat pump water heater is provided, comprising a water tank, a plurality of temperature sensors, and a controller; wherein the plurality of temperature sensors are arranged in sequence and at intervals along the height direction of the water tank, and the plurality of temperature sensors respectively detect the water temperature at different water levels in the water tank; the temperature sensor is electrically connected to the controller; and the controller is used to execute the water heater control method as described in any of the above embodiments.

[0118] In the specific contents of the above-mentioned specific implementation methods, the various technical features can be combined in any non-contradictory manner. In order to make the description concise, not all possible combinations of the above-mentioned technical features are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0119] The specific contents of the above specific implementations only express several implementations of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention.

Claims

1. A heat pump water heater control method, characterized in that: The water tank of the heat pump water heater is provided with a plurality of temperature sensors, and the plurality of temperature sensors are sequentially spaced apart along the height direction of the water tank; the method comprises: Based on the reference ambient temperature, determining a reference water tank temperature from the water tank temperatures detected by the plurality of temperature sensors; the reference ambient temperature is determined based on at least one period of historical ambient temperature and / or predicted ambient temperature; If the reference water tank temperature is lower than the set temperature, the target superheat is determined based on the magnitude relationship between the reference water tank temperature and the corresponding water tank temperature threshold; the water tank temperature threshold is lower than the set temperature; Based on the target superheat, the expansion valve opening is adjusted.

2. The method according to claim 1, characterized in that The step of determining the reference water tank temperature from the water tank temperatures detected by the plurality of temperature sensors based on the reference ambient temperature comprises: If the reference ambient temperature is greater than the first ambient temperature, the reference water tank temperature is determined to be the first reference water tank temperature, where the first reference water tank temperature is the water tank temperature corresponding to the first water level; If the reference ambient temperature is between the second ambient temperature and the first ambient temperature, the reference water tank temperature is determined to be the second reference water tank temperature, the second reference water tank temperature is the water tank temperature corresponding to the second water level; the first water level is higher than the second water level; the second ambient temperature is lower than the first ambient temperature; If the reference ambient temperature is lower than the second ambient temperature, the reference water tank temperature is determined to be a third reference water tank temperature, and the third reference water tank temperature is a water tank temperature corresponding to a third water level; the second water level is higher than the third water level.

3. The method according to claim 2, characterized in that If the reference water tank temperature is the first reference water tank temperature, determining the target superheat degree based on the magnitude relationship between the reference water tank temperature and the corresponding water tank temperature threshold includes: If the first reference water tank temperature is less than the water tank temperature threshold, determining the target superheat degree to be a first superheat degree; If the first reference water tank temperature is greater than or equal to the water tank temperature threshold, the target superheat degree is determined to be a second superheat degree; and the second superheat degree is greater than the first superheat degree.

4. The method according to claim 2, characterized in that: If the reference water tank temperature is the second reference water tank temperature, determining the target superheat degree based on the magnitude relationship between the reference water tank temperature and the corresponding water tank temperature threshold includes: Obtaining a reference water tank temperature difference; the reference water tank temperature difference is the difference between the maximum water tank temperature and the minimum water tank temperature among the water tank temperatures detected by the temperature sensors; If the second reference water tank temperature is less than the water tank temperature threshold, comparing the reference water tank temperature difference with the first temperature difference threshold; If the reference water tank temperature difference is less than the first temperature difference threshold, determining the target superheat degree to be the first superheat degree; If the reference water tank temperature difference is greater than the first temperature difference threshold, the target superheat is determined to be a second superheat; and the second superheat is greater than the first superheat.

5. The method according to claim 4, characterized in that After obtaining the reference water tank temperature difference, the method further includes: If the second reference water tank temperature is greater than the water tank temperature threshold, then comparing the reference water tank temperature difference with the second temperature difference threshold; the second temperature difference threshold is greater than the first temperature difference threshold; If the reference water tank temperature difference is less than the second temperature difference threshold, determining the target superheat degree to be the second superheat degree; If the reference water tank temperature difference is greater than the second temperature difference threshold, the target superheat is determined to be a third superheat; and the third superheat is greater than the second superheat.

6. The method according to claim 2, characterized in that If the reference water tank temperature is the third reference water tank temperature, determining the target superheat degree based on the magnitude relationship between the reference water tank temperature and the corresponding water tank temperature threshold includes: Obtaining a reference water tank temperature difference; the reference water tank temperature difference is the difference between the maximum water tank temperature and the minimum water tank temperature among the water tank temperatures detected by the temperature sensors; If the third reference water tank temperature is less than the water tank temperature threshold, comparing the reference water tank temperature difference with the first temperature difference threshold; If the reference water tank temperature difference is less than the first temperature difference threshold, determining the target superheat degree to be the first superheat degree; If the reference water tank temperature difference is greater than the first temperature difference threshold, the target superheat is determined to be a second superheat; and the second superheat is greater than the first superheat.

7. The method according to claim 6, characterized in that After obtaining the reference water tank temperature difference, the method further includes: If the third reference water tank temperature is greater than the water tank temperature threshold, then comparing the reference water tank temperature difference with a second temperature difference threshold; the second temperature difference threshold is greater than the first temperature difference threshold; If the reference water tank temperature difference is less than the second temperature difference threshold, determining the target superheat degree to be the first superheat degree; If the reference water tank temperature difference is greater than the second temperature difference threshold, the target superheat is determined to be a third superheat; and the third superheat is greater than the first superheat.

8. The method according to any one of claims 4 to 7, characterized in that: The method further comprises: If the reference water tank temperature difference is greater than a first temperature difference threshold, or the reference water tank temperature difference is greater than a second temperature difference threshold, the fan speed of the water heater is increased.

9. The method according to any one of claims 1 to 8, characterized in that: The step of adjusting the expansion valve opening based on the target superheat comprises: If the current superheat is greater than the target superheat, increasing the opening of the expansion valve; If the current superheat is less than the target superheat, the expansion valve opening is reduced.

10. A heat pump water heater, characterized in that: It includes a water tank, a plurality of temperature sensors, and a controller; A plurality of the temperature sensors are sequentially arranged at intervals along the height direction of the water tank, and the temperature sensors are electrically connected to the controller; The controller is used to execute the heat pump water heater control method described in any one of claims 1-9.

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