Method for controlling hot water supply and air conditioning unit and hot water supply and air conditioning unit

Abstract

To provide a control method of a hot water supply air conditioning unit capable of improving energy efficiency while suppressing enlargement of a tank, and the hot water supply air conditioning unit.SOLUTION: This control method of the hot water supply air conditioning unit 1A is a control method of the hot water supply air conditioning unit 1A for heating water in a tank 31 by a heat pump 21 of an air conditioning side unit 2, and executes low temperature rising operation having a smaller temperature rising range than maximum rising range operation for raising the temperature from the minimum temperature of the water in the tank 31 to a target using temperature by the heat pump 21.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a hot water supply air conditioning unit and a method for controlling a hot water supply air conditioning unit. [Background technology]

[0002] Conventionally, a control device has been proposed that supplies heat recovered from a refrigeration circuit that cools a refrigerator or freezer to an air conditioning unit or a hot water supply unit (see, for example, Patent Document 1). The control device described in Patent Document 1 aims to improve the operating efficiency of the entire system by switching whether or not to exchange heat with the refrigerant in the exhaust heat recovery machine. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2023-135438 Summary of the Invention [Problem to be solved by the invention]

[0004] Since all of the devices covered by the control device described in Patent Document 1 can use a heat pump, the heat pump can be shared among these devices. For example, a hot water supply air conditioning unit that uses the heat pump of an air conditioner to heat the water in the tank of a water heater can be considered.

[0005] When using an air conditioner's heat pump to heat water in a water heater's tank, it may not be possible to install a large tank due to space limitations in the home. While providing a backup heating means in addition to the heat pump can compensate for the lack of tank capacity, this can result in reduced efficiency. Furthermore, heating water using a heat pump filled with air conditioning refrigerant can result in operation below the critical point of the refrigerant, potentially resulting in reduced heating efficiency.

[0006] The present invention has been made in consideration of the above-mentioned problems, and its purpose is to provide a control method for a hot water supply air conditioning unit and a hot water supply air conditioning unit that can improve energy efficiency while suppressing the increase in size of the tank. [Means for solving the problem]

[0007] In order to achieve the above-mentioned object, the control method for a hot water supply air conditioning unit of the present invention is a control method for a hot water supply air conditioning unit that heats the water in a tank using a heat pump of an air conditioning side unit, and is characterized in that it performs a low temperature rise operation with a smaller temperature rise range than the maximum rise range operation that uses the heat pump to raise the water temperature in the tank from the lowest temperature to a target operating temperature.

[0008] In one embodiment of the method for controlling a hot water air conditioning unit of the present invention, the temperature rise width in one low temperature rise operation is set within a predetermined temperature range, and water at or above the target operating temperature is obtained by performing multiple low temperature rise operations.

[0009] In a control method for a hot water air conditioning unit according to one embodiment of the present invention, the height of water flowing from the heat pump to the tank is determined based on the temperature of the water after the temperature rise due to the low temperature rise operation and the temperature of the water in the tank.

[0010] In one embodiment of the control method for a hot water air conditioning unit of the present invention, the height of water to be extracted from the tank to the heat pump is determined based on the water temperature at each height in the tank, the temperature rise range of the low temperature rise operation, and the target operating temperature.

[0011] In a method for controlling a hot water supply air conditioning unit according to one aspect of the present invention, the heat pump is started a predetermined time before a time when a large amount of water in the tank is expected to be consumed.

[0012] In one aspect of the present invention, in a control method for a hot water supply air conditioning unit, the water in the tank can be heated by multiple air conditioning side units in the hot water supply air conditioning unit, and the air conditioning side unit that heats the water in the tank is selected based on the heating / cooling operation status of the air conditioning side units.

[0013] In one embodiment of the control method for a hot water supply air conditioning unit of the present invention, the water in the tank can be heated by a plurality of air conditioning side units in the hot water supply air conditioning unit, and the water in the tank is heated by at least two of the plurality of air conditioning side units during a time when a large amount of water in the tank is expected to be used.

[0014] In one aspect of the present invention, in a control method for a hot water air conditioning unit, the air conditioning unit is capable of simultaneously performing cooling operation and heating operation, and during the low temperature rise operation, the water in the tank can be heated by utilizing the exhaust heat generated when the air conditioning unit is operating in cooling mode.

[0015] In one embodiment of the control method for a hot water supply air conditioning unit of the present invention, the heat pump includes two refrigeration cycles and is connected to a high-temperature side heat exchanger of one refrigeration cycle and a low-temperature side heat exchanger of the other refrigeration cycle.

[0016] In one embodiment of the present invention, a control method for a hot water air conditioning unit includes the hot water air conditioning unit having at least one of a solar water heater and a bath heat recovery device capable of heating the water in the tank, and a heat source for heating the water in the tank is selected depending on the operating conditions of the air conditioning unit and at least one of the solar water heater and the bath heat recovery device.

[0017] In one aspect of the present invention, in a control method for a hot water supply air conditioning unit, the water in the tank can be heated by multiple air conditioning side units in the hot water supply air conditioning unit, and the multiple air conditioning side units are operated in a coordinated manner based on demand power information.

[0018] On the other hand, the hot water supply air conditioning unit of the present invention is a hot water supply air conditioning unit that heats the water in the tank using a heat pump in an air conditioning side unit, and is equipped with a control unit that controls the heat pump, and is characterized in that the control unit performs a low temperature rise operation with a smaller temperature rise range than the maximum rise range operation that uses the heat pump to raise the water temperature in the tank from the lowest temperature to the target usage temperature. [Effects of the Invention]

[0019] According to the hot water supply air conditioning unit control method and the hot water supply air conditioning unit of the present invention, it is possible to improve energy efficiency while suppressing an increase in the size of the tank. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a block diagram schematically showing a hot water supply air conditioning unit according to a first embodiment of the present invention. [Figure 2] 1 is a block diagram showing an outline of the equipment configuration of an air conditioning side unit of a hot water supply air conditioning unit according to a first embodiment of the present invention. [Figure 3] 5 is a flowchart showing an example of a multi-stage heating process performed by a control unit of the hot water supply air conditioning unit according to the first embodiment of the present invention. [Figure 4] FIG. 3 is a schematic diagram showing temperature changes in the tank of the hot water supply air conditioning unit according to the first embodiment of the present invention. [Figure 5] FIG. 5 is a block diagram schematically showing a hot water supply air conditioning unit according to a second embodiment of the present invention. [Figure 6] 10 is a flowchart showing an example of an inflow height determination process carried out by a control unit of a hot water supply air conditioning unit according to a second embodiment of the present invention. [Figure 7] FIG. 10 is a block diagram schematically showing a hot water supply air conditioning unit according to a third embodiment of the present invention. [Figure 8] 11 is a flowchart showing an example of an extraction height determination process carried out by a control unit of a hot water supply air conditioning unit according to a third embodiment of the present invention. [Figure 9]FIG. 10 is a schematic diagram showing a tank and a plurality of air conditioning side units of a hot water supply air conditioning unit according to a first modified example of the present invention. [Figure 10] FIG. 10 is a schematic diagram showing a tank and a plurality of air conditioning side units of a hot water supply air conditioning unit according to a second modified example of the present invention. [Figure 11] FIG. 10 is a system diagram showing a refrigeration cycle of a hot water supply air conditioning unit according to a third modified example of the present invention. [Figure 12] FIG. 10 is a schematic diagram showing a tank and a refrigeration cycle of a hot water supply air conditioning unit according to a third modified example of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0021] [First embodiment] A first embodiment of the present invention will be described below with reference to the drawings. Fig. 1 is a block diagram schematically showing a hot water supply air conditioning unit 1A according to the first embodiment of the present invention, Fig. 2 is a block diagram showing an outline of the equipment configuration of an air conditioning unit 2 of the hot water supply air conditioning unit 1A, Fig. 3 is a flowchart showing an example of a multi-stage heating process performed by a control unit 4 of the hot water supply air conditioning unit 1A, and Fig. 4 is a schematic diagram showing temperature changes in a tank 31 of the hot water supply air conditioning unit 1A.

[0022] As shown in Figure 1, the control method for the hot water supply air conditioning unit 1A according to the first embodiment of the present invention is a control method for the hot water supply air conditioning unit 1A in which the water in the tank 31 is heated by the heat pump 21 of the air conditioning side unit 2, and a low temperature rise operation with a smaller temperature rise range than the maximum rise range operation for raising the temperature of the water in the tank 31 from the lowest temperature to the target operating temperature by the heat pump 21 is performed.

[0023] The hot water supply air conditioning unit 1A includes an air conditioning side unit 2, a hot water supply side unit 3, a control unit 4, a flow path unit 5 through which water passes, and a temperature measuring unit 6. Hereinafter, water before heating will be referred to as "cold water," and water after heating will be referred to as "hot water." When simply referring to "water," this includes both cold water and hot water, and the temperature is not particularly limited.

[0024] The air conditioning unit 2 is a unit with air conditioning functions and is composed of a heat pump 21, an outdoor unit 22, and an indoor unit 23. As shown in FIG. 2, the heat pump 21 has a compressor 24, an outdoor air heat exchanger 25, a water heat exchanger 26, an expansion valve 27A for the air heat exchanger 25, an expansion valve 27B for the water heat exchanger 26, and an indoor air heat exchanger 28. Only the air heat exchanger 28 is provided in the indoor unit 23, and the rest are provided in the outdoor unit. The air conditioning unit 2 also has a fan for blowing air in the indoor unit 23, but this is not shown. In this way, the heat pump 21 forms a refrigeration cycle, and the refrigeration cycle includes a four-way switching valve (not shown) that allows the direction of fluid flow to be switched, i.e., allows switching between cooling and heating operation. The air conditioning unit 2 may be a dedicated product for the hot water supply air conditioning unit 1A, or a general-purpose product may be used for the air conditioning unit 1A. The refrigerant used in the refrigeration cycle of the air conditioning unit 2 may be any refrigerant for air conditioning, such as R32.

[0025] The amount by which the temperature of the water raised by the heat pump 21 varies depending on the rotation speed of the compressor and the rotation speed of the water pump 50, which will be described later; the higher the rotation speed of the compressor, the easier the temperature rises, and the higher the rotation speed of the water pump 50, the greater the flow rate of water passing through per unit time, making it more difficult for the temperature to rise. In this embodiment, the compressor can be set to operate in three operating states: rated operation, where the rotation speed is a predetermined value; economical operation, where the rotation speed is lower than the rated operation (for example, 30% of the rated operation); and maximum operation, where the rotation speed is higher than the rated operation (for example, 120% of the rated operation), and the rotation speed can also be set to an intermediate value between these.

[0026] The hot water supply side unit 3 is a unit for supplying hot water, and includes a tank 31, a backup heating means 32, and an in-tank temperature measuring unit 33 that measures the amount of water in the tank 31. The tank 31 is formed in a cylindrical shape that extends along the vertical direction, and below, the top and bottom in the vertical direction may be simply referred to as top and bottom.

[0027] Tank 31 has cold water inlet 311 located at the lower end, outlet 312 located at the lower end, hot water inlet 313 located at the upper end, and hot water outlet 314 located at the upper end. In this embodiment, cold water inlet 311 and outlet 312 are independent openings, but they may be a common opening, and in this embodiment, hot water inlet 313 and hot water outlet 314 are independent openings, but they may be a common opening. Furthermore, cold water inlet 311 and outlet 312 may be slightly offset from the lower end of the tank, and hot water inlet 313 and hot water outlet 314 may be slightly offset from the upper end of the tank.

[0028] Backup heating means 32 heats water using a method other than a heat pump, and may be, for example, an electric heater or a gas heater. When there is a shortage of water in tank 31 at the target use temperature at hot water supply destination 20, water at the target use temperature is supplied by heating the water using backup heating means 32. Here, the "target use temperature" may be a temperature set on the panel as the temperature actually used by the user (i.e., a temperature that can vary depending on the user's setting), or it may be a temperature that is higher than the temperature that the user can set and does not vary.

[0029] The tank temperature measuring unit 33 is composed of, for example, multiple temperature sensors arranged vertically inside the tank, and by measuring the temperature at each height, it is possible to measure the amount of water that is at or above a predetermined temperature (for example, the above-mentioned target use temperature).

[0030] The control unit 4 is configured by, for example, a microcomputer including a CPU (Central Processing Unit). In Fig. 1, the control unit 4 is independent from the air conditioning unit 2, but the control unit 4 may be part of the air conditioning unit 2. The control unit 4 may also be part of the hot water supply unit 3, or a control unit 4 independent from the air conditioning unit 2 and the hot water supply unit 3 may be provided, or a single control unit that controls the entire hot water supply air conditioning unit 1A may be provided.

[0031] The control unit 4 receives signals from at least the tank internal temperature measuring unit 33 and the temperature measuring unit 6, and transmits signals to at least the heat pump 21 and the valves and water pump 50 provided in each part of the flow path unit 5. The transmission and reception of signals may be performed by wireless communication or by wired communication.

[0032] The flow path section 5 has a cold water supply path 51 extending from the water supply source 10 to the cold water inlet portion 311, a heat pump inlet path 52 extending from the outlet portion 312 to the inlet of the heat pump 21, a heat pump outlet path 53 extending from the outlet of the heat pump 21 to the hot water inlet portion 313, and a hot water supply path 54 extending from the hot water outlet portion 314 to the hot water supply destination 20. Valves are provided at each portion of the flow path section 5, allowing the flow paths to be switched as appropriate. A water pump 50 is provided in the flow path section 5 upstream of the heat pump 21, allowing the flow rate of water passing through the heat pump 21 per unit time to be adjusted. Note that the location and number of water pumps are not limited to these, as long as the flow rate of water passing through the heat pump 21 per unit time can be adjusted.

[0033] The temperature measuring unit 6 has an inlet temperature measuring unit 61 provided in the heat pump inlet flow path 52 and an outlet temperature measuring unit 62 provided in the heat pump outlet flow path 53.

[0034] In the hot water supply air conditioning unit 1A of this embodiment, water is heated (normal heating) at a predetermined time, for example, once a day. The timing of normal heating may be set by the user, or may be determined based on the electricity rate for each time period and the hot water usage history. The hot water supply air conditioning unit 1A may also perform emergency heating when the amount of hot water used is high and the remaining amount in the tank 31 is low. The heat pump 21 is assumed to be stopped except when heating is being performed. In either case of heating, the air conditioning side unit 2 is assumed to have its air conditioning function stopped or to be operating in heating mode.

[0035] The control unit 4 may perform hot water supply preparatory operation, which will be described below, during emergency heating. The timing for performing hot water supply preparatory operation is a predetermined time before the expected heavy usage time, when it is expected that more water than a predetermined amount will be used in the tank. For example, if a household often fills the water tank at a predetermined time, the expected heavy usage time may be determined based on such usage history. Also, if the water tank filling is set in advance by a timer, this time may be used as the expected heavy usage time.

[0036] Hot water supply preliminary operation is a type of low temperature rise operation described below, in which the heat pump 21 is started a predetermined time before the expected heavy usage time and the compressor rotation speed is set lower than that of rated operation. This predetermined time may be determined, for example, based on the time required to start the heat pump 21, and is preferably about twice the required time. The compressor rotation speed during hot water supply preliminary operation may be set to the lowest possible speed, for example, about 20% of that of rated operation.

[0037] After the hot water supply preparatory operation has started, if a predetermined time has passed and the tub has been filled with water, and if the user uses hot water, the control unit 4 will transition from the hot water supply preparatory operation to another operating state and increase the rotation speed of the compressor. At this time, the operation may be switched to a multi-stage heating process, which will be described later, or if the amount of hot water used is large, the water may be heated in one stage, or backup heating means 32 may be used in combination as appropriate.

[0038] If a certain time has passed since the start of hot water supply preparatory operation without the water being filled, or if a certain time has passed since the water has been filled, the hot water supply preparatory operation can be terminated and the heat pump 21 can be stopped.

[0039] Here, an example of the multi-stage heating process executed by the control unit 4 will be described with reference to the flowchart of Fig. 3. The multi-stage heating process may be performed in the normal boiling process as described above, or in the special boiling process.

[0040] The control unit 4 first acquires remaining amount information indicating the amount of water remaining in the tank 31 that is at or above the target use temperature from the tank internal temperature measuring unit 33, and determines whether the remaining amount is equal to or above a first threshold (step S1). The first threshold may be set to, for example, about 30% of the maximum capacity of the tank. If the remaining amount is less than the first threshold (NO in step S1), the control unit 4 operates the compressor at maximum speed and activates the heat pump 21 (step S2).

[0041] On the other hand, if the remaining amount is equal to or greater than the first threshold (YES in step S2), the control unit 4 determines whether the remaining amount is equal to or greater than a second threshold (step S3). The second threshold is higher than the first threshold and may be set to, for example, approximately 70% of the maximum capacity of the tank. If the remaining amount is equal to or greater than the second threshold (YES in step S3), the control unit 4 operates the heat pump 21 with the compressor in economical operation (step S4). On the other hand, if the remaining amount is less than the second threshold (NO in step S3), the control unit 4 operates the heat pump 21 with the compressor in rated operation (step S5).

[0042] After operating the heat pump 21 in steps S2, S4, and S5, the control unit 4 acquires the inlet temperature T I from the inlet temperature measuring unit 61 and the outlet temperature T O from the outlet temperature measuring unit 62, and calculates the temperature rise value ΔT, which is the difference between the outlet temperature T O and the inlet temperature T I (step S6). That is, the control unit 4 calculates the temperature rise value ΔT of the water caused by the heat pump 21 by calculating the temperature difference between the upstream and downstream sides of the heat pump 21.

[0043] Next, the control unit 4 determines whether the temperature rise value ΔT is equal to or greater than the temperature rise upper limit TUL (step S7). If the temperature rise value ΔT is equal to or greater than the temperature rise upper limit TUL (YES in step S7), the control unit 4 determines whether the pump flow rate FL of the water pump 50 is less than the upper limit FUL (step S8). At this time, the control unit 4 may obtain information about the flow rate FL of the water pump 50 by storing a history of signals transmitted to the water pump 50, or may obtain information about the flow rate FL of the water pump 50 by obtaining information about the current operating state from the heat pump 21.

[0044] If the flow rate FL of the water pump 50 is less than the upper limit FUL (YES in step S8), the control unit 4 increases the flow rate FL of the water pump 50 (step S9), and proceeds to step S15, which will be described later. On the other hand, if the flow rate FL of the water pump 50 is equal to or greater than the upper limit FUL (NO in step S8), the control unit 4 reduces the rotation speed of the compressor (step S10), and proceeds to step S15, which will be described later.

[0045] If the temperature rise value ΔT is less than the temperature rise width upper limit TUL (NO in step S7), the control unit 4 determines whether the temperature rise value ΔT is equal to or less than the temperature rise width lower limit TLL (step S11).If the temperature rise value ΔT is equal to or less than the temperature rise width lower limit TLL (YES in step S11), the control unit 4 determines whether the flow rate FL of the water pump 50 is greater than the lower limit FLL (step S12).

[0046] If the flow rate FL of the water pump 50 is greater than the lower limit FLL (YES in step S12), the control unit 4 reduces the flow rate FL of the water pump 50 (step S13), and proceeds to step S15, which will be described later. On the other hand, if the flow rate FL of the water pump 50 is equal to or less than the lower limit FLL (NO in step S12), the control unit 4 increases the rotation speed of the compressor (step S14), and proceeds to step S15, which will be described later.

[0047] If the temperature rise value ΔT is greater than the temperature rise range lower limit TLL (NO in step S11), the control unit 4 acquires the outlet temperature TO from the outlet temperature measuring unit 62 and determines whether the time during which the outlet temperature TO is equal to or higher than the target use temperature TT continues for a predetermined time or more (step S15). If this continuation time is less than the predetermined time (NO in step S15), the control unit 4 returns to step S6 again, and if the continuation time is the predetermined time (YES in step S15), the control unit 4 ends the multi-stage heating process. Note that when acquiring and determining temperature information in step S6, the information may be acquired after a predetermined waiting time has elapsed since the previous step.

[0048] Next, a specific example of temperature change when the temperature of the water in tank 31 is increased by the above-described multistage heating process will be described with reference to Figure 4. First, before the start of the multistage heating process, as shown in Figure 4(A), it is assumed that tank 31 is filled only with cold water at 5°C supplied from water supply source 10. In addition, the upper limit TUL of the temperature rise range is set to 30°C, the lower limit TLL of the temperature rise range is set to 20°C, and the target use temperature TT is set to 45°C (first temperature condition).

[0049] Under the first temperature condition, in step S3 of the multistage heating process, it is determined that the remaining amount is equal to or greater than the second threshold. Immediately after the start of operation of the heat pump 21, the temperature rise value ΔT is less than 20°C due to economical operation, but the temperature rise value ΔT is adjusted to 20-30°C in steps S11 to S14. In this case, because economical operation is started, the temperature rise value ΔT becomes approximately equal to 20°C, which is the temperature rise range lower limit TLL.

[0050] Water heated by heat pump 21 flows into tank 31 through upper hot water inlet 313, and the temperature of the water in the upper part of tank 31 becomes relatively high. By repeating steps S6 to S15, an upper layer of water that has been heated once (5 + 20 = 25°C) and a lower layer of unheated water (5°C) are formed, as shown in Figure 4(B). By further repeating steps S6 to S15, all of the water in tank 31 becomes water that has been heated once, as shown in Figure 4(C).

[0051] In the state shown in Figure 4(C), the temperature of the water taken out from the outlet 312 is 25°C, is heated by the heat pump 21 to 45°C, and flows into the tank 31 from the hot water inlet 313. By continuing this second heating, an upper layer of water that has been heated twice and a lower layer of water that has been heated once are formed, as shown in Figure 4(D). At this time, the outlet temperature TO acquired by the outlet temperature measuring unit 62 is equal to or higher than the target use temperature TT, and therefore the multi-stage heating process ends after a predetermined time has elapsed.

[0052] In the state shown in FIG. 4(D), water having a temperature equal to or higher than the target use temperature TT is stored in the tank 31, so hot water can be used without using the backup heating means 32.

[0053] By performing the multi-stage heating process as described above, the temperature rise width per heating by the heat pump 21 is smaller (e.g., 20 to 30°C) than the maximum rise width operation (e.g., 40°C) for raising the water temperature in the tank from the lowest temperature (e.g., 5°C) to the target use temperature (e.g., 45°C) using the heat pump 21, and a low temperature rise operation is performed. Furthermore, the temperature rise width in one low temperature rise operation is within a predetermined temperature range (e.g., 20 to 30°C). Furthermore, by performing such a low temperature rise operation multiple times, water at or above the target use temperature can be obtained.

[0054] As described above, according to the control method for a hot water supply air conditioning unit according to the first embodiment of the present invention, by performing a low-temperature rise operation with a smaller temperature rise than the maximum rise operation, the compression ratio of the refrigerant is reduced, preventing the compressed refrigerant from leaking through gaps to the low-pressure section, thereby improving energy efficiency. This is particularly effective when an air-conditioning refrigerant is used in the refrigeration cycle of the air-conditioning unit 2. Furthermore, this highly energy-efficient heating improves the maximum heating capacity of the hot water supply air conditioning unit, and even if the tank 31 is made smaller and the backup heating means 32 performs emergency heating more frequently, the amount of heat generated by the backup heating means 32 can be reduced. In this way, energy efficiency can be improved without increasing the size of the tank 31.

[0055] In addition, by setting the temperature rise range in a single low temperature rise operation within a predetermined temperature range and obtaining water at or above the target operating temperature through multiple low temperature rise operations, it is possible to obtain water at or above the target operating temperature while improving energy efficiency, even if there is a large difference between the temperature of the water supply source 10 and the target operating temperature.

[0056] Furthermore, by starting the heat pump 21 a predetermined time before the expected time of large-volume use of water in the tank 31, the time required to bring the heat pump 21 to rated operation when large amounts of water are used can be made shorter than the time required to bring the heat pump 21 to rated operation from a completely stopped state. Therefore, even in low-temperature rise operation, the time required to obtain water at or above the target use temperature can be shortened, and the use of the backup heating means 32 can be suppressed, thereby improving energy efficiency.

[0057] [Second embodiment] In the second and subsequent embodiments, components having the same functions as the hot water supply air conditioning unit 1A of the first embodiment are given the same reference numerals and their description is omitted, and differences from the hot water supply air conditioning unit 1A will be mainly described.

[0058] As shown in FIG. 3, the hot water supply air conditioning unit 1B according to the second embodiment of the present invention differs from the hot water supply air conditioning unit 1A according to the first embodiment in that the tank 31 is further provided with intermediate inlet sections 315, 316 and a lower inlet section 317, the flow path section 5 further has intermediate flow paths 55, 56 and a lower flow path 57, and the temperature measuring section 6 further has an upper temperature measuring section 63 and intermediate temperature measuring sections 64, 65.

[0059] It is preferable that the intermediate inlet section 315 is provided above the vertical center of the tank 31, and the intermediate inlet section 316 is provided below the vertical center of the tank 31. In this embodiment, two intermediate inlet sections 315, 316 are provided, but only one intermediate inlet section may be provided, or three or more intermediate inlet sections may be provided. The lower inlet section 317 is provided at the vertical lower end of the tank 31 (i.e., near the cold water inlet section 311 and the outlet section 312).

[0060] The intermediate flow path 55 extends from the outlet of the heat pump 21 to the upper intermediate inlet section 315, and the intermediate flow path 56 extends from the outlet of the heat pump 21 to the lower intermediate inlet section 316. The lower flow path 57 extends from the outlet of the heat pump 21 to the lower inlet section 317, that is, it is a flow path for heating water taken out from the bottom of the tank 31 and returning it to the bottom of the tank 31.

[0061] The upper temperature measuring unit 63 measures the temperature of the water in the tank 31 at or near the hot water inlet 313, the middle temperature measuring unit 64 measures the temperature of the water in the tank 31 at or near the upper middle inlet 315, and the middle temperature measuring unit 65 measures the temperature of the water in the tank 31 at or near the lower middle inlet 316. Signals of measured temperature information are transmitted from the upper temperature measuring unit 63 and the middle temperature measuring units 64, 65 to the control unit 4.

[0062] The flow path unit 5 is provided with a valve for switching the position from which the water that has passed through the heat pump 21 flows into the tank 31, and the valve is opened and closed based on a signal received from the control unit 4. For example, if the water that has passed through the heat pump 21 is to flow into the tank 31 from the intermediate inlet 315, the valves provided in the heat pump outlet flow path 53, the valves provided in the intermediate flow path 56, and the valves provided in the lower flow path 57 may be closed, and only the valve provided in the intermediate flow path 55 may be opened.

[0063] An example of the inflow height determination process executed by the control unit 4 will now be described with reference to the flowchart of Fig. 6. The inflow height determination process may be executed while the heat pump 21 is operating. It may be executed all the time the heat pump 21 is operating, or may be executed only when, for example, there is little water in the tank 31 that is at or above the target operating temperature (this may be measured directly or estimated from the operating history of the heat pump 21, etc.). The inflow height determination process may also be incorporated into the multi-stage heating process as in the first embodiment, and may be executed after the heat pump 21 is operated in steps S2, S4, and S5, for example. Even when the inflow height determination process is executed independently of the multi-stage heating process, the heat pump 21 will still be in low-temperature-rise operation.

[0064] In the inflow height determination process, the control unit 4 first acquires information on the outlet temperature TO from the outlet temperature measuring unit 62 and information on the upper temperature TU from the upper temperature measuring unit 63 (step S101), and determines whether the outlet temperature TO is equal to or higher than the upper temperature TU (step S102). If the outlet temperature TO is equal to or higher than the upper temperature TU (YES in step S102), the control unit 4 selects the hot water inlet 313 as the inlet (step S103). That is, the control unit 4 sends a signal to the switching unit so that water flows into the tank 31 only from the uppermost hot water inlet 313.

[0065] If the outlet temperature TO is lower than the upper temperature TU (NO in step S102), the control unit 4 acquires information on the first intermediate temperature TM1 from the intermediate temperature measuring unit 64 (step S104) and determines whether the outlet temperature TO is equal to or higher than the first intermediate temperature TM1 (step S105). If the outlet temperature TO is equal to or higher than the first intermediate temperature TM1 (YES in step S105), the control unit 4 selects the upper intermediate inlet section 315 as the inlet section (step S106). That is, the control unit 4 sends a signal to the switching unit so that water flows into the tank 31 only from the second-highest intermediate inlet section 315 among the inlet sections.

[0066] If the outlet temperature TO is less than the first intermediate temperature TM1 (NO in step S105), the control unit 4 acquires information on the second intermediate temperature TM2 from the intermediate temperature measuring unit 65 (step S107) and determines whether the outlet temperature TO is equal to or greater than the second intermediate temperature TM2 (step S108). If the outlet temperature TO is equal to or greater than the second intermediate temperature TM2 (YES in step S108), the control unit 4 selects the lower intermediate inlet section 316 as the inlet section (step S109). That is, the control unit 4 sends a signal to the switching unit so that water flows into the tank 31 only from the third uppermost intermediate inlet section 316 among the inlet sections.

[0067] If the outlet temperature TO is lower than the second intermediate temperature TM2 (NO in step S108), the control unit 4 selects the lower inlet portion 317 as the inlet portion (step S110). That is, the control unit 4 sends a signal to the switching unit so that water flows into the tank 31 only from the lowest lower inlet portion 317.

[0068] After selecting the inlet portion (steps S103, S106, S109, and S110), the control unit 4 returns to step S101 again. When the heat pump 21 stops, the control unit 4 ends the inlet height determination process.

[0069] In this way, in the inflow height determination process, the control unit 4 compares the temperature of the water that has passed through the heat pump 21 with the temperature of the water at each height in the tank 31 to determine which of the four inflow ports to allow water to flow into the tank 31. In other words, the control unit 4 determines the inflow height of water from the heat pump 21 to the tank 31 based on the temperature of the water after the temperature rise due to low temperature rise operation and the temperature of the water in the tank 31.

[0070] In the above example of the inflow height determination process, the inflow height is determined only by comparing the outlet temperature TO with the temperature at each height, i.e., the uppermost inflow portion is selected so that the outlet temperature TO is higher than the temperature inside the tank 31. However, the present invention is not limited to this type of control. For example, the outlet temperature TO may be compared with the temperature at each height inside the tank 31 first, and an inflow portion at a height where the temperature inside the tank 31 is higher and the difference between the temperature of the tank 31 and the outlet temperature TO is the smallest may be selected.

[0071] In this way, according to the hot water supply air conditioning unit 1B of the second embodiment of the present invention, the height of water flowing from the heat pump 21 into the tank 31 is determined based on the temperature of the water after the temperature rise due to low temperature rise operation and the temperature of the water in the tank 31. This makes it possible to prevent the temperature of the water at the top of the tank 31 from dropping even if the temperature of the water passing through the heat pump 21 is below the target operating temperature, and makes it possible to avoid using the backup heating means 32, thereby improving energy efficiency.

[0072] [Third embodiment] As shown in FIG. 7, the hot water supply air conditioning unit 1C according to the third embodiment of the present invention differs from the hot water supply air conditioning unit 1A according to the first embodiment in that the tank 31 further includes an intermediate extraction section 318, the flow path section 5 further includes an intermediate extraction flow path 58, and the temperature measuring section 6 further includes an intermediate temperature measuring section 66 and a lower temperature measuring section 67.

[0073] The intermediate removal section 318 is preferably provided in the vertical center of the tank 31. Although one intermediate removal section 318 is provided in this embodiment, a plurality of intermediate removal sections may be provided.

[0074] The intermediate extraction flow path 58 extends from the intermediate extraction section 318 to the inlet of the heat pump 21 .

[0075] The intermediate temperature measuring unit 66 measures the temperature of the water in the tank 31 at or near the intermediate discharge unit 318, and the lower temperature measuring unit 67 measures the temperature of the water in the tank 31 at or near the discharge unit 312. Signals of measured temperature information are transmitted from the intermediate temperature measuring unit 66 and the lower temperature measuring unit 67 to the control unit 4.

[0076] The flow path unit 5 is provided with a valve for switching which position in the tank 31 water is extracted from and sent to the heat pump 21, and the valve is opened and closed based on a signal received from the control unit 4. For example, when extracting water from the intermediate extraction unit 318, the valve provided in the heat pump inlet flow path 52 is closed and the valve provided in the intermediate extraction flow path 58 is opened.

[0077] An example of the extraction height determination process executed by the control unit 4 will now be described with reference to the flowchart in Figure 8. The extraction height determination process is executed when the heat pump 21 is operated under predetermined conditions. The predetermined conditions are when it is determined that there is a risk of a shortage of water at or above the target operating temperature, such as during or immediately after the water is filled. The control unit 4 may execute the extraction height determination process when the water is filled, or when the amount of water remaining in the tank 31 falls below a predetermined value.

[0078] The operation mode of the heat pump 21 when executing the extraction height determination process may be based on the multi-stage heating process as in the first embodiment, or may be other low-temperature rising operation. Furthermore, the extraction height determination process may be executed simultaneously with the inflow height determination process as in the second embodiment.

[0079] In the unloading height determination process, the control unit 4 first acquires the lower temperature TL from the lower temperature measuring unit 67 (step S201), and determines whether the sum of the lower temperature TL and the normal temperature rise value ΔTN is equal to or less than the target operating temperature TT (step S202). The normal temperature rise value ΔTN is a normal temperature rise value in low temperature rise operation, and in a multi-stage heating process such as the first embodiment, for example, it may be an intermediate value between the upper temperature rise limit TUL and the lower temperature rise limit TLL.

[0080] If the sum of the lower temperature TL and the normal temperature rise value ΔTN is equal to or less than the target operating temperature TT (YES in step S202), the control unit 4 acquires a third intermediate temperature TM3 from the intermediate temperature measuring unit 66 (step S203) and determines whether the sum of the third intermediate temperature TM3 and the normal temperature rise value ΔTN is equal to or greater than the target operating temperature TT (step S204).If the sum of the third intermediate temperature TM3 and the normal temperature rise value ΔTN is equal to or greater than the target operating temperature TT (YES in step S204), the control unit 4 determines whether the third intermediate temperature TM3 is less than the target operating temperature TT (step S205).

[0081] If the third intermediate temperature TM3 is lower than the target use temperature TT (YES in step S205), the control unit 4 selects the intermediate extraction unit 318 as the extraction position (step S206). That is, the control unit 4 opens and closes the valve so that only the water extracted from the intermediate extraction unit 318 flows toward the heat pump 21. After step S206, the control unit 4 returns to step S201.

[0082] When the sum of the lower temperature TL and the normal temperature rise value ΔTN is greater than the target use temperature TT (NO in step S202), when the sum of the third intermediate temperature TM3 and the normal temperature rise value ΔTN is less than the target use temperature TT (NO in step S204), or when the third intermediate temperature TM3 is equal to or greater than the target use temperature TT (NO in step S205), the control unit 4 selects the outlet 312 as the take-out position (step S207). That is, the control unit 4 opens and closes the valve so that only water taken out from the outlet 312 flows toward the heat pump 21. After step S207, the control unit 4 returns to step S201. Examples of timings at which the control unit 4 terminates the take-out height determination process include when the heat pump 21 stops, when a predetermined time has elapsed since the start of the take-out height determination process, or when the amount of water in the tank 31 that is at or above the target use temperature reaches or exceeds a predetermined amount.

[0083] In this way, in the extraction height determination process, the control unit 4 determines the extraction height of water from the tank 31 to the heat pump 21 based on the temperature of the water at each height in the tank 31, the normal temperature rise value ΔTN which is the temperature rise range for low temperature rise operation, and the target operating temperature TT.

[0084] If the outlet 312 is selected as the outlet position in step S207, water below the target use temperature TT may flow into the upper part of the tank 31, causing the temperature of the water supplied to the hot water supply destination 20 to be below the target use temperature TT. In this case, the backup heating means 32 may be used. Furthermore, if the water heated by the heat pump 21 is below the target use temperature TT, the water may be configured to flow into the tank 31 from a location other than the upper part, as in the second embodiment.

[0085] In this way, according to the hot water supply air conditioning unit 1C of the third embodiment of the present invention, the height of water to be taken out from the tank 31 to the heat pump 21 is determined based on the water temperature at each height in the tank 31, the normal temperature rise value ΔTN which is the temperature rise range for low temperature rise operation, and the target operating temperature TT, making it easier to obtain water at a temperature above the target operating temperature even in low temperature rise operation, thereby reducing the use of the backup heating means 32 and improving energy efficiency.

[0086] The present invention is not limited to the above-described embodiments, and includes other configurations that can achieve the object of the present invention, and the following modifications are also included in the present invention. For example, in the above-described first to third embodiments of the present invention, the hot water supply unit 3 has one tank 31, but the water heater may have multiple tanks. When the water heater has multiple tanks, for example, these may be connected in series, and a hot water outlet may be provided at the top of the tank on one end of the connection direction, and a cold water inlet may be provided at the bottom of the tank on the other end.

[0087] Furthermore, in the first to third embodiments, the hot water supply air conditioning units 1A to 1C each include one air conditioning-side unit 2, but the hot water supply air conditioning unit may be capable of heating water in a tank by connecting multiple outdoor units, and for example, three air conditioning-side units 2A to 2C may be connected in parallel as shown in Fig. 9, or two air conditioning-side units 2A and 2B may be connected in series to one air conditioning-side unit 2C as shown in Fig. 10. Although Figs. 9 and 10 illustrate the connection of the air conditioning-side units 2A to 2C, the air conditioning-side units 2A to 2C may have water heat exchangers in their outdoor units as in the air conditioning-side units 2 of the first to third embodiments, as long as the water heat exchangers are connected to each other.

[0088] As described above, when heating water, the air conditioning unit must be stopped or in heating mode. When multiple air conditioning units 2A to 2C are used as shown in Figures 9 and 10, an air conditioning unit to heat the water in the tank 31 is selected based on the heating / cooling operation status of the air conditioning units 2A to 2C. In other words, the water in the tank 31 is heated using an air conditioning unit that is stopped or operating in heating mode.

[0089] In this case, the multiple air conditioning units 2A to 2C are often installed in different rooms and operate in different heating and cooling modes, such as when air conditioning unit 2A is installed in a child's room, air conditioning unit 2B is installed in the living room, and air conditioning unit 2C is installed in the master bedroom. When multiple air conditioning units are stopped or operating in heating mode, only one unit may be used, or multiple units may be coordinated. It is particularly preferable to use at least two units during periods when large amounts of water are expected to be used, and multiple units may be coordinated to perform multi-stage heating treatment.

[0090] In this way, by selecting the air conditioning unit to heat the water in the tank 31 based on the heating / cooling operation status of the multiple air conditioning units 2A to 2C, it is easy to heat the water in the tank 31 even during times when there is demand for cooling. Furthermore, by using at least two units during times when a large amount of water is expected to be used, heating capacity can be improved, reducing the need for backup heating and making it easy to improve energy efficiency. In particular, when multiple air conditioning units are connected in series, the temperature rise per air conditioning unit can be reduced, making it easy to perform low-temperature rise operation.

[0091] Furthermore, when multiple air conditioning units are operated in a coordinated manner, the coordinated operation may be based on power demand information. That is, the multiple air conditioning units may be operated in a coordinated manner to heat water, taking into consideration the balance between the power demand in the entire area to which the home in which the hot water supply air conditioning unit is installed and the amount of power generated in that area by a power source (such as a solar power generation system) with relatively large fluctuations in power generation amount.

[0092] Furthermore, in the first to third embodiments, the air conditioning unit 2 is capable of switching between cooling and heating operations and cannot simultaneously perform cooling and heating operations. However, an air conditioning unit capable of simultaneously performing cooling and heating operations may be used. In this case, during low temperature rise operation, the water in the tank can be heated using the exhaust heat generated when the air conditioning unit is in cooling operation, thereby improving energy efficiency. Whether or not to utilize the exhaust heat from the cooling operation can be determined based on whether or not the conditions are such that the cooling operation will not be affected. For example, the exhaust heat from the cooling operation may be utilized when the inlet temperature of the heat pump is below a predetermined temperature (e.g., the outside air temperature).

[0093] Furthermore, in the first to third embodiments, water is heated by the heat pump 21 including one refrigeration cycle, but a heat pump including two refrigeration cycles may also be used. That is, the high-temperature heat exchanger in one of the two refrigeration cycles may be connected to the low-temperature heat exchanger in the other, and the temperature may be raised by each of the two refrigeration cycles (raising the temperature in two stages), and then the water may be heated by the high-temperature heat exchanger in the other. An example of such a heat pump 2D is shown in Figure 11.

[0094] The heat pump 2D includes a low-temperature side refrigeration cycle 211 and a high-temperature side refrigeration cycle 212. The low-temperature side refrigeration cycle 211 includes an expansion valve 211A, an evaporator 211B as a low-temperature side heat exchanger, and a compressor 211C. The high-temperature side refrigeration cycle 212 includes an expansion valve 212A, a condenser 212B as a high-temperature side heat exchanger, and a compressor 212C. The high-temperature side heat exchanger of the low-temperature side refrigeration cycle 211 and the low-temperature side heat exchanger of the high-temperature side refrigeration cycle 212 are integrated (i.e., connected) to form a cascade condenser 213.

[0095] The low-stage side refrigeration cycle 211 is a refrigeration cycle for air conditioning using a refrigerant such as R32, as in the first to third embodiments, and the high-stage side refrigeration cycle 212 is a refrigeration cycle dedicated to hot water supply using a refrigerant such as R134a. In the example shown in Fig. 12, water taken out from an outlet 312 at the bottom of the tank 31 can be heated only by the low-stage side refrigeration cycle 211 and can flow into the tank 31 from the vertical center, and water taken out from the outlet 312 at the bottom of the tank 31 can be heated by both the low-stage side refrigeration cycle 211 and the high-stage side refrigeration cycle 212 and can flow into the tank 31 from the vertical upper part.

[0096] By using the two refrigeration cycles 211, 212 in this way, the temperature rise per refrigeration cycle can be made smaller than the temperature rise when only one refrigeration cycle is used, that is, low temperature rise operation can be easily achieved.

[0097] Furthermore, a configuration in which a high-side refrigeration cycle 212 is provided in addition to the low-side refrigeration cycle 211 may be employed in an air conditioning unit capable of switching between cooling and heating operations as described above. When using exhaust heat from cooling operation to heat water, the water temperature after heating may not reach the target operating temperature, but even in such a case, the high-side refrigeration cycle 212 can be used to heat the water to the target operating temperature, thereby making effective use of the exhaust heat from cooling and improving energy efficiency.

[0098] Furthermore, in the first to third embodiments, only the heat pump 21 of the air-conditioning unit 2 is used as a heat source other than the backup heating means 32. However, other heat sources may also be used. For example, a solar hot water heater or a bath heat recovery device may be provided as a heat source, and one of the air-conditioning units 2A to 2C shown in FIGS. 9 and 10 may be replaced with another heat source. In this case, the heat source for heating the water in the tank 31 may be selected depending on the operating status of the air-conditioning unit and the other heat source. For example, when all of the air-conditioning units are operating in cooling mode or when heat can be easily recovered by the solar hot water heater or the bath heat recovery device, the solar hot water heater or the bath heat recovery device may be used preferentially to heat the water in the tank 31.

[0099] Although the embodiments of the present invention have been described above, the present invention is not limited to the hot water supply air conditioning unit according to the above embodiments, and includes all aspects encompassed by the concept and scope of the present invention. Furthermore, each configuration may be appropriately and selectively combined to achieve at least some of the above-described problems and advantages. For example, the shape, material, arrangement, size, etc. of each component in the above embodiments may be appropriately modified depending on the specific use of the present invention. [Explanation of symbols]

[0100] 1A to 1C... hot water supply air conditioning unit, 2, 2A to 2C... air conditioning side unit, 21... heat pump, 211, 212... refrigeration cycle, 3... hot water supply side unit, 31... tank, 4... control unit

Claims

1. A control method for a hot water supply air conditioning unit that heats water in a tank using a heat pump of an air conditioning unit, comprising: A control method for a hot water supply air conditioning unit, characterized in that a low temperature rise operation is performed with a smaller temperature rise range than the maximum rise range operation required for the heat pump to raise the water temperature in the tank from the lowest temperature to the target operating temperature.

2. A control method for a hot water air conditioning unit as described in claim 1, characterized in that the temperature rise range in one low temperature rise operation is set within a predetermined temperature range, and water at a target operating temperature or higher is obtained by performing the low temperature rise operation multiple times.

3. A control method for a hot water supply air conditioning unit as described in claim 1, characterized in that the height of water flowing from the heat pump to the tank is determined based on the temperature of the water after the temperature rise due to the low temperature rise operation and the temperature of the water in the tank.

4. A control method for a hot water supply air conditioning unit as described in claim 1, characterized in that the height of water to be taken out from the tank to the heat pump is determined based on the water temperature at each height in the tank, the temperature rise range of the low temperature rise operation, and the target operating temperature.

5. 5. The method for controlling a hot water supply air conditioning unit according to claim 1, wherein the heat pump is started a predetermined time before a time when a large amount of water in the tank is expected to be consumed.

6. In the hot water supply air conditioning unit, the water in the tank can be heated by a plurality of air conditioning side units, A control method for a hot water supply air conditioning unit according to any one of claims 1 to 4, characterized in that an air conditioning side unit that heats the water in the tank is selected based on the heating and cooling operation status of the air conditioning side unit.

7. In the hot water supply air conditioning unit, the water in the tank can be heated by a plurality of air conditioning side units, A control method for a hot water supply air conditioning unit described in any one of claims 1 to 4, characterized in that the water in the tank is heated by at least two of the multiple air conditioning units during a time when large amounts of water are expected to be used in the tank.

8. The air conditioning unit is capable of simultaneously performing cooling and heating operations, A control method for a hot water supply air conditioning unit described in any one of claims 1 to 4, characterized in that during the low temperature rise operation, the water in the tank can be heated by utilizing the exhaust heat when the air conditioning side unit is operating in cooling mode.

9. A method for controlling a hot water air conditioning unit according to any one of claims 1 to 4, characterized in that the heat pump includes two refrigeration cycles and is connected to a high-temperature side heat exchanger of one refrigeration cycle and a low-temperature side heat exchanger of the other refrigeration cycle.

10. The hot water supply air conditioning unit includes at least one of a solar water heater and a bath heat recovery device that can heat the water in the tank, A control method for a hot water air conditioning unit described in any one of claims 1 to 4, characterized in that a heat source for heating the water in the tank is selected depending on the operating conditions of the air conditioning side unit and at least one of the solar water heater and the bath heat recovery unit.

11. In the hot water supply air conditioning unit, the water in the tank can be heated by a plurality of air conditioning side units, 5. The method for controlling a hot water supply air conditioning unit according to claim 1, wherein the plurality of air conditioning units are operated in a coordinated manner based on power demand information.

12. A hot water supply air conditioning unit that heats the water in the tank using a heat pump in an air conditioning unit, a control unit for controlling the heat pump; The control unit is characterized in that it performs a low temperature rise operation with a smaller temperature rise range than the maximum rise range operation used by the heat pump to raise the water temperature in the tank from the lowest temperature to the target operating temperature.

Images