Heating system and heat source unit

Abstract

To provide a warming system that enables control so as to prevent discharge pressure of a compressor from exceeding an upper limit value and enables improvement of reliability by suppressing failure or lowering of a service life of the compressor.SOLUTION: A hot water generation device 1 includes: a refrigeration cycle 20 comprising a compressor 21, a condenser 23, an expansion valve 24, an air blowing fan 26 and an evaporator 25 through which outdoor air passes by using the air blowing fan 26; a use side apparatus 31 that is a warming target; an annular medium flow passage 32 connecting the condenser 23 of the refrigeration cycle 20 and the use side apparatus 31 to circulate a heating medium; an outlet temperature sensor 13 detecting an outlet side temperature of the heating medium in the condenser 23; and a control section 5 setting an upper limit value of the outlet side temperature of the heating medium in the condenser 23 on the basis of a flow rate of the heating medium circulating in the medium flow passage 32 and controlling operation frequency of the compressor 21 in accordance with the upper limit value.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a heating system and a heat source unit. [Background technology]

[0002] *When there is a singular example, we use the notation "etc.", and when there are multiple examples, we use the notation "etc." There is known a heating system using a heat pump type heat source machine that generates hot water using a heat pump type refrigeration cycle. A heating system such as a hot water supply system or a floor heating system supplies a heat medium such as hot water to a load to be heated to perform heating or other heating. Here, a heat source unit, which is a heat pump type heat source machine that uses air such as outside air as a heat source, is used as a means for heating water.

[0003] For example, a heating system includes a heat pump cycle having a ring-shaped refrigerant flow path connecting a compressor, a water heat exchanger, an expansion valve, and an air heat exchanger, a hot water storage tank for storing hot water for hot water supply, and a hot water flow path connecting the water heat exchanger and the hot water storage tank. The heating system controls the expansion valve to open when the difference between the refrigerant temperature at the outlet side of the refrigerant flow path and the hot water temperature at the inlet side of the hot water flow path becomes smaller than a target temperature difference, and controls the expansion valve to close when the difference between the refrigerant temperature at the outlet side of the refrigerant flow path and the hot water temperature at the inlet side of the hot water flow path becomes larger than the target temperature difference.

[0004] However, when the temperature difference between the refrigerant temperature at the outlet side of the refrigerant flow path and the fluid temperature at the inlet side of the fluid flow path is smaller than the target temperature difference and the expansion valve is controlled to open, the heating system controls the refrigerant pressure on the high-pressure side of the heat pump cycle to be equal to or higher than a predetermined refrigerant pressure so as to ensure the target hot water temperature of the hot water fluid. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2002-206805 A Summary of the Invention [Problem to be solved by the invention]

[0006] Conventional heating systems regulate the compressor discharge pressure so as not to deviate from the operating pressure range by setting the upper limit of the target hot water temperature lower as the outside air temperature increases.

[0007] However, in such a heating system, when the circulation flow rate is high, the temperature difference between the refrigerant temperature at the outlet side of the refrigerant flow path and the fluid temperature at the inlet side of the fluid flow path becomes small. As a result, the inlet water temperature and the compressor discharge pressure when the target outlet temperature is reached become high, and the compressor discharge pressure may deviate from the operating pressure range. In this case, the load on the compressor becomes large, and there is a risk of the compressor breaking down or its lifespan being shortened.

[0008] Therefore, the present invention aims to provide a heating system that can control the compressor discharge pressure so that it does not exceed an upper limit by appropriately regulating the upper limit value of the target outlet temperature, thereby improving reliability by suppressing compressor failures and shortened lifespan. [Means for solving the problem]

[0009] In order to solve the above problems, a heating system according to an embodiment of the present invention includes a refrigeration cycle including a compressor, a first heat exchanger, a throttling device, a blower fan, and a second heat exchanger through which outdoor air is ventilated by the blower fan; a utilization side device to be heated; a ring-shaped medium flow path that connects the first heat exchanger of the refrigeration cycle and the utilization side device to circulate a heat medium; and an outlet temperature sensor that detects an outlet temperature of the heat medium in the first heat exchanger. a flow rate detection unit that detects the flow rate of the heat medium circulating through the medium flow path; an outside air temperature sensor that detects the outside air temperature; The flow rate of the heat medium circulating through the medium flow path and the outside air temperature detected by the outside air temperature sensor.and a control unit that sets an upper limit value of an outlet side temperature of the heat medium in the first heat exchanger based on the upper limit value of the outlet side temperature, and prevents a discharge pressure of the compressor from exceeding an upper limit value by controlling an operation frequency of the compressor in accordance with the upper limit value of the outlet side temperature, determining a correction value for correcting the upper limit value of the outlet side temperature based on the outside air temperature; When the lower limit of the flow rate is R1, the correction coefficient at R1 is α1, the rated value of the flow rate is R2, the correction coefficient at R2 is α2, the upper limit of the flow rate is R3, and the correction coefficient at R3 is α3, α1=α2×R2÷R1, α2=1, and α3=α2×R2÷R3, the upper limit of the outlet side temperature is the set temperature of α1, α2, and α3. , and the correction value Based on Correct it It is set based on.

[0010] Also, a heat source unit according to an embodiment of the present invention includes a refrigeration cycle including a compressor, a first heat exchanger, a throttling device, a blower fan, and a second heat exchanger through which outdoor air is ventilated by the blower fan; a piping joint for connecting the first heat exchanger of the refrigeration cycle to a utilization side device and connecting to an annular medium flow path that circulates a heat medium; and an outlet temperature sensor for detecting an outlet temperature of the heat medium in the first heat exchanger. a flow rate detection unit that detects the flow rate of the heat medium circulating through the medium flow path; an outside air temperature sensor that detects the outside air temperature; The flow rate of the heat medium circulating through the medium flow path and the outside air temperature detected by the outside air temperature sensor. and a control unit that sets an upper limit value of an outlet side temperature of the heat medium in the first heat exchanger based on the upper limit value of the outlet side temperature, and prevents a discharge pressure of the compressor from exceeding an upper limit value by controlling an operation frequency of the compressor in accordance with the upper limit value of the outlet side temperature, determining a correction value for correcting the upper limit value of the outlet side temperature based on the outside air temperature; When the lower limit of the flow rate is R1, the correction coefficient at R1 is α1, the rated value of the flow rate is R2, the correction coefficient at R2 is α2, the upper limit of the flow rate is R3, and the correction coefficient at R3 is α3, α1=α2×R2÷R1, α2=1, and α3=α2×R2÷R3, the upper limit of the outlet side temperature is the set temperature of α1, α2, and α3. , and the correction value Based on Correct it It is set based on. [Brief description of the drawings]

[0011] [Figure 1]FIG. 2 is a system diagram showing a refrigeration cycle of the heating system according to the embodiment. [Diagram 2] 2 is a block diagram illustrating a control unit in the heating system of FIG. 1. [Diagram 3] 6 is a graph showing the relationship between the outside air temperature and the upper limit regulation of the outlet side temperature. [Figure 4] 6 is a graph showing the relationship between the circulation flow rate and a correction coefficient. [Diagram 5] 4 is a flowchart showing a control process of the heating system. [Figure 6] 10 is a flowchart showing a control process in a modified example of the heating system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a protection circuit and an electric device will be described in detail with reference to the drawings.

[0013] FIG. 1 is a system diagram showing a refrigeration cycle circuit of a heating system according to an embodiment.

[0014] FIG. 2 is a block diagram that illustrates a control unit in the heating system of FIG.

[0015] FIG. 3 is a graph showing the relationship between the outside air temperature and the upper limit regulation of the outlet side temperature.

[0016] FIG. 4 is a graph showing the relationship between the circulation flow rate and the correction coefficient.

[0017] As shown in FIG. 1, the heating system of this embodiment is a heat pump type hot water generator 1. The hot water generator 1 is roughly divided into a heat source unit 2 that exchanges heat between a refrigerant and outdoor air (outdoor air) and between water supplied from outside the device and the refrigerant, and a user-side heat exchanger 31 that is a load unit 3 such as a floor heating device connected to the heat source unit 2. The hot water generator 1 also includes a controller 29 as an input device that accepts operations by a user, and a control unit 5 that controls the heat source unit 2 and the load unit 3 based on the operation of the controller 29. The controller 29 includes a display unit made of a liquid crystal or the like, and is configured to display the setting contents and the operating state on the display unit. The controller 29 sets the set temperature of the hot water desired by the user.

[0018] The heat source unit 2 has a refrigeration cycle 20 in which a refrigerant circulates, in which a compressor 21, a four-way valve 22, a condenser 23 functioning as a first heat exchanger (a water heat exchanger in this case), an expansion valve 24 as a throttling device, and an evaporator 25 functioning as a second heat exchanger (an air heat exchanger in this case) are sequentially connected by refrigerant piping 28. The evaporator 25 is provided with a blower fan 26 and an outside air temperature sensor 11 that detects the outside air temperature (TO). The compressor 21 is configured by incorporating a compression mechanism and a DC brushless motor that drives the compression mechanism in a high-pressure container. The DC brushless motor of the compressor 21 is driven at a variable speed by the output of a three-phase inverter device 51 that receives power from a commercial AC power source.

[0019] In the hot water generating apparatus 1, the refrigeration cycle 20 is configured so that the refrigerant circulates in a circular manner in sequence through a compressor 21, a four-way valve 22, a condenser 23, an expansion valve 24, an evaporator 25, and the four-way valve 22, which are connected by a refrigerant piping 28.

[0020] The load unit 3 includes a user side device 31 and a circulation pump 33. In the hot water generating device 1, the condenser 23 functioning as a water heat exchanger in the heat source unit 2 and the user side device 31 of the load unit 3 are connected by a ring-shaped medium flow path 32 that circulates water as a heat medium. A variable speed circulation pump 33 is provided in the medium flow path 32 on the load unit 3 side, and the circulation pump 33 circulates water between the condenser 23 and the user side device 31, exchanges heat between the refrigerant and water in the condenser 23, and supplies heated hot water to the user side device 31. The heated hot water flows through a floor heating system such as a heating device as the user side device 31 and is returned to the condenser 23 in the heat source unit 2. That is, the water circulates between the heat source unit 2 and an external heat radiator such as a radiator of the heating device as the user side device 31. The medium flow path 32 is provided with pipe joints 35, 36, and the heat source unit 2 and the load unit 3 can be detached via these pipe joints 35, 36. Generally, water is suitable as the heat medium, but antifreeze can also be used to prevent freezing.

[0021] An inlet temperature sensor 12 is provided on the inlet side of the condenser 23 of the medium flow path 32 to detect the inlet temperature (TWI) of water as a heat medium. An outlet temperature sensor 13 is provided on the outlet side of the condenser 23 of the medium flow path 32 to detect the outlet temperature (TWO) of water as a heat medium. Furthermore, a flow meter 27 is provided in the medium flow path 32 in the heat source unit 2 as a flow rate detector to detect the flow rate (circulation flow rate R) of water as a heat medium circulating through the medium flow path 32. Note that the water circulation flow rate R is not limited to the flow rate detected by the flow meter 27, but may be a flow rate stored in advance corresponding to the rotation speed of the circulation pump 33, a flow rate set by manual input, or an estimated flow rate may be used and corrected if a change occurs during operation. Note that the flow meter 27 may be provided in the middle of the medium flow path 32 on the load unit 3 side. Similarly, the circulation pump 33 may be located either on the load unit 3 side or in the medium flow path 32 in the heat source unit 2.

[0022] 2, the control unit 5 controls the operation of the heat source unit 2 and the load unit 3 based on the operation of the controller 29. That is, the control unit 5 controls the operation of the compressor 21, the inverter device 51, the four-way valve 22, the expansion valve 24, the blower fan 26, etc. based on the operation of the user via the controller 29 (such as an operation input operation or a temperature setting operation). The control unit 5 also controls the operation of at least the compressor 21 or the blower fan 26 out of the compressor 21, the four-way valve 22, the expansion valve 24, and the blower fan 26 based on one or more of various detection values ​​by various sensors such as at least the outside air temperature sensor 11, the inlet temperature sensor 12, and the outlet temperature sensor 13, or a detection value by the flowmeter 27.

[0023] The control unit 5 of this embodiment is configured as a computer having hardware resources such as a processor (CPU) (not shown), memory and its peripheral circuits, and in which information processing by software is realized using the hardware resources as the CPU executes various programs.

[0024] Here, the compressor 21 compresses the refrigerant and discharges it in a high-temperature, high-pressure state. The refrigerant is compressed and pressurized, and discharged in a high-temperature, high-pressure state. The compressor 21 can change its operating frequency by known inverter control. By increasing the rotation speed of the compressor 21, the amount of heat transferred to the high-temperature portion increases, and by decreasing the rotation speed, the amount of heat transferred to the high-temperature portion decreases. The refrigerant used in this embodiment is R410A or R32, for example. Furthermore, the expansion valve 24 is, for example, an electronic expansion valve (Pulse Motor Valve: PMV), and its opening degree can be adjusted. The expansion valve 24 is arranged in series in the refrigerant pipe 28 between the condenser 23 and the evaporator 25, and reduces the pressure of the refrigerant to a low-temperature, low-pressure state.

[0025] Evaporator 25 exchanges heat between the refrigerant and air blown by blower fan 26 installed nearby. Outside air temperature sensor 11 is installed upstream of evaporator 25 in the direction of air blown by blower fan 26 to detect an accurate outside air temperature (hereinafter, also referred to as outside air temperature).

[0026] The refrigeration cycle 20 performs a defrosting operation by switching the flow direction of the refrigerant in the refrigerant pipe 28 by the four-way valve 22 during the operation of heating water. When performing the defrosting operation, the hot water generating device 1 reverses the four-way valve 22 to cause the refrigerant to flow in the refrigeration cycle 20 in the opposite direction to the flow of the refrigerant that heats water to hot water. That is, the refrigerant flows through the compressor, the four-way valve 22, the second heat exchanger 25, the expansion valve 24, the first heat exchanger 23, the four-way valve 22, and the compressor 21 in that order. During this defrosting operation, the second heat exchanger 25 functions as a condenser to melt frost attached to its surface, and the first heat exchanger 23 functions as an evaporator.

[0027] For warm regions where defrosting operation is not required, the refrigeration cycle 20 may be dedicated to heating water and does not include the four-way valve 22. In this case, the discharge side of the compressor 21 is connected to the condenser 23 via the refrigerant pipe 28, and the suction side of the compressor 21 is connected to the evaporator 25 via the refrigerant pipe 28.

[0028] In the hot water generating device 1 configured in this manner, the control unit 5 controls the output frequency of the inverter device 51 to increase or decrease the rotation speed of the compressor 21 so that the temperature of the heat medium circulating through the medium flow path 32 becomes the set temperature set by the user, thereby controlling the amount of heating of the water (hot water) supplied to the user side equipment 31.

[0029] Here, in the hot water generating apparatus 1, the higher the outside air temperature, the higher the discharge pressure of the compressor 21. Therefore, the higher the outside air temperature, the lower the upper limit of the outlet side temperature in the condenser 23 of the medium flow path 32 must be set. Therefore, the upper limit of the outlet side temperature is set based on the outside air temperature and the circulating flow rate of the heat medium. A correction value ΔT for correcting the upper limit of the outlet side temperature is determined based on the outside air temperature, and a correction coefficient α is set based on the circulating flow rate of the heat medium. The upper limit of the outlet side temperature is set by these two parameters, the correction value ΔT and the correction coefficient α.

[0030] The relationship between the outside air temperature and the correction value ΔT for correcting the upper limit of the outlet temperature in the condenser 23 of the medium flow path 32 is as shown in FIG. 3, which shows the outside air temperature on the horizontal axis and the correction value ΔT on the vertical axis. For example, at P4 where the outside air temperature is 40°C, the correction value ΔT is -1.0. At the rated circulation flow rate where the correction coefficient α is 1, the upper limit of the outlet temperature, which is the target value, is calculated by the upper limit of the outlet temperature = the set temperature + ΔT. Therefore, when the outside air temperature is 40°C, the setting of the upper limit of the outlet temperature needs to be corrected so that it is 1°C lower than the set temperature. Note that linear interpolation is performed between P1 and P6 in FIG. 3. Note that when the outside air temperature is lower than point P2 in FIG. 3, the discharge temperature does not rise to a temperature that requires protection, so the correction value ΔT remains "0".

[0031] In the hot water generating apparatus 1, when the circulating flow rate of water is low, the temperature difference between the inlet side temperature and the outlet side temperature in the condenser 23 of the medium flow path 32 becomes large, whereas when the circulating flow rate of water is high, the temperature difference between the inlet side temperature and the outlet side temperature in the condenser 23 of the medium flow path 32 becomes small. Therefore, when the circulating flow rate of water is low, it is necessary to increase the regulation of the upper limit value of the outlet side temperature in the condenser 23, i.e., to lower the upper limit value, whereas when the circulating flow rate of water is high, it is possible to decrease the regulation of the upper limit value of the outlet side temperature in the condenser 23, i.e., to raise the upper limit value.

[0032] The relationship between the circulation flow rate R and the correction coefficient α for the upper limit of the outlet temperature in the condenser 23 of the medium flow path 32 is as shown in FIG. 4, which shows the circulation flow rate R on the horizontal axis and the correction coefficient α on the vertical axis. If the lower limit of the circulation flow rate is R1, the rated circulation flow rate is R2, the upper limit of the circulation flow rate is R3, and the correction coefficients for the respective circulation flow rates R1 to R3 are α1, α2, and α3, then α1=α2×R2÷R1 and α3=α2×R2÷R3. Note that the correction coefficient α2 is 1 for the rated value of the circulation flow rate R2. The upper limit of the outlet temperature in the condenser 23 taking into account the circulation flow rate R is expressed as "upper limit of the outlet temperature=set temperature+ΔT×α". Note that between P2 and P4 in FIG. 4, Approximation curve passing through P2 to P4 is interpolated.

[0033] In this manner, in the hot water generating device 1 of this embodiment, the frequency is controlled to target the upper limit of the outlet temperature relative to the set temperature set by the user according to the circulation flow rate R of the water in the medium flow path 32. That is, in the hot water generating device 1 of this embodiment, the upper limit of the outlet temperature in the condenser 23 is corrected in consideration of the circulation flow rate R of the water in the medium flow path 32, and the controller 5 controls the inverter device 51 to control the operating frequency of the compressor 21 with the corrected upper limit as the target value of the outlet temperature in the condenser 23. As a result, the outlet temperature of the condenser 23 is controlled so as not to exceed the upper limit of the outlet temperature. That is, if the outlet temperature of the condenser 23 exceeds the upper limit of the outlet temperature, the operating frequency of the compressor 21 is immediately reduced to control the outlet temperature of the condenser 23 to be equal to or lower than the upper limit of the outlet temperature.

[0034] Next, the control operation of the compressor 21 by the control unit 5 in the hot water generating apparatus 1 of this embodiment will be described.

[0035] FIG. 5 is a flowchart showing the control process of the heating system.

[0036] 6 is a flowchart showing a control process in a modified example of the heating system. In the following description, each "step" in the flowchart will be abbreviated as "ST."

[0037] As shown in Fig. 5, first, the control unit 5 judges whether or not a signal related to the start of operation has been input from the controller 29 (ST1), and waits until the signal related to the start of operation is input (ST1: No). Then, when the signal related to the start of operation is input (ST1: Yes), the control unit 5 judges whether or not the inlet side temperature of the condenser 23 of the medium flow path 32 is lower than the set temperature (ST2), and if the inlet side temperature is higher than the set temperature, heating of the heat medium is not necessary, so the control unit 5 waits until the inlet side temperature becomes lower than the set temperature (ST2: No). Then, when the inlet side temperature of the condenser 23 is lower than the set temperature (ST2: Yes), the control unit 5 starts the operation of the compressor 21 to start heating the heat medium (ST3), and acquires the outside air temperature from the outside air temperature sensor 11 (ST4).

[0038] Next, the control unit 5 calculates a correction value ΔT of the outlet temperature of the condenser 23 of the medium flow path 32 according to the outside air temperature based on the acquired outside air temperature as shown in Fig. 3 (ST5). Next, the control unit 5 acquires the circulating flow rate R of the water in the medium flow path 32 by the flowmeter 27 (ST6).

[0039] Next, the control unit 5 calculates a correction coefficient α for the upper limit value of the outlet side temperature in the condenser 23 of the medium flow path 32 as shown in FIG. 4 (ST7).

[0040] Next, the set temperature+ΔT×α, which is the target upper limit of the outlet side temperature of the condenser 23 of the medium flow path 32 based on the set temperature, is calculated (ST8).

[0041] Next, the control unit 5 determines whether the current outlet temperature detected by the outlet temperature sensor 13 is higher than the upper limit of the outlet temperature (ST10), and if the current outlet temperature is higher than the upper limit (ST10: Yes), the control unit 5 lowers the operation frequency of the compressor 21 (ST11) to prevent the compressor 21 from being overloaded. On the other hand, if the current outlet temperature is lower than the upper limit (T10: No), the control unit 5 determines that the load of the compressor 21 is sufficient, and therefore increases the operation frequency of the compressor 21 to further increase the temperature of the circulating heat medium (ST12). That is, the control unit 5 sets the upper limit of the outlet temperature in the condenser 23 of the medium flow path 32 taking into account the acquired outside air temperature, and controls the operation frequency of the compressor 21 by increasing or decreasing it so that the outlet temperature detected by the outlet temperature sensor 13 becomes the set upper limit.

[0042] Next, the control unit 5 judges whether the inlet side temperature in the condenser 23 of the medium flow path 32 is equal to or higher than the set temperature (ST13), and repeats these routines of ST1 to ST12 (ST13: No) until the inlet side temperature becomes equal to or higher than the set temperature. When the inlet side temperature in the condenser 23 of the medium flow path 32 becomes equal to or higher than the set temperature (ST13: Yes), the temperature of the heat medium has risen sufficiently, and further operation would cause the temperature of the heat medium to rise too much, so the operation of the compressor 21 is stopped (ST14), and the process returns to ST1. In other words, the control unit 5 determines the operation frequency of the compressor 21 according to the set temperature and the inlet side temperature detected by the inlet temperature sensor 12.

[0043] In the hot water generating device 1 of this embodiment, the operation control of the compressor 21 by the control unit 5 is not limited to the above-mentioned procedure. For example, as shown in FIG. 6 in which the same reference numerals are used for parts corresponding to those in FIG. 5, the control unit 5 calculates the target frequency of the compressor 21 for the set temperature (ST20). Here, in the embodiment shown in FIG. 5, the operation frequency of the compressor 21 is determined in ST11 and ST12 for controlling the outlet side temperature so as not to exceed the upper limit value. In contrast, in the modified example shown in FIG. 6, the target frequency of the compressor is first calculated based on the difference between the set temperature and the inlet side temperature detected by the inlet temperature sensor 12. In this calculation, PI control and PID control can be used. It is determined in ST21 whether the calculated target frequency is the actual operation frequency. In ST21, it is determined whether the current outlet side temperature detected by the outlet temperature sensor 13 is higher than the upper limit value of the outlet side temperature. At this time, if the current outlet side temperature is higher than the upper limit value (ST21: Yes), the control unit 5 reduces the operation frequency of the compressor 21 to a value lower than the operation frequency at that time (ST22). On the other hand, if the current outlet side temperature is lower than the upper limit (ST21: No), there is no need to limit the operating frequency, so the operation of the compressor 21 is controlled at the target frequency calculated in the previous ST20 (ST23). That is, the control unit 5 controls the operating frequency of the compressor 21 so that the outlet side temperature detected by the outlet temperature sensor does not exceed the set upper limit of the outlet side temperature. In this method, when the outlet side temperature is lower than the upper limit, the compressor is operated at the target frequency of the compressor calculated based on the difference between the set temperature and the inlet side temperature, so that the stability of the operating frequency of the compressor is increased.

[0044] In this way, the hot water generating device 1 compares the set temperature with the outlet side temperature so as not to exceed the upper limit value of the outlet side temperature set according to the circulation flow rate R, and performs protective control to lower the operating frequency of the compressor 21 if the outlet side temperature is about to exceed the upper limit.

[0045] As described above, according to the hot water generating apparatus 1 and heat source unit of this embodiment, the control unit 5 controls the frequency of the compressor 21 so that the outlet side temperature of the condenser 23 does not exceed the upper limit value set based on the flow rate of the heat medium, such as water, in the condenser 23 of the medium flow path 32, thereby controlling the discharge pressure of the compressor 21 so that it does not exceed the upper limit value, i.e., so that it does not deviate from the operating pressure range of the compressor 21.By suppressing failures and shortening of the lifespan of the compressor 21, the reliability of the hot water generating apparatus 1 and the heat source unit can be improved.

[0046] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0047] 1...hot water generating device, 2...heat source unit, 3...load unit, 5...control unit, 11...outside air temperature sensor, 12...inlet temperature sensor, 13...outlet temperature sensor, 20...refrigeration cycle, 21...compressor, 22...four-way valve, 23...condenser (first heat exchanger, water heat exchanger), 24...expansion valve, 25...evaporator (second heat exchanger, air heat exchanger), 26...blower fan, 27...flow meter, 28...refrigerant piping, 29...controller, 31...user equipment, 32...medium flow path, 33...circulation pump, 51...inverter device.

Claims

1. a refrigeration cycle including a compressor, a first heat exchanger, a throttling device, a blower fan, and a second heat exchanger through which outdoor air is ventilated by the blower fan; A user device to be heated; a ring-shaped medium flow path that connects the first heat exchanger of the refrigeration cycle and the utilization side device and circulates a heat medium; an outlet temperature sensor for detecting an outlet side temperature of the heat medium in the first heat exchanger; a flow rate detection unit that detects a flow rate of the heat medium circulating through the medium flow path; an outside air temperature sensor for detecting an outside air temperature; a control unit that sets an upper limit value of an outlet side temperature of the heat medium in the first heat exchanger based on the flow rate of the heat medium circulating through the medium flow path detected by the flow rate detection unit and the outside air temperature detected by the outside air temperature sensor, and prevents a discharge pressure of the compressor from exceeding an upper limit value by controlling an operation frequency of the compressor in accordance with the upper limit value of the outlet side temperature, determining a correction value for correcting the upper limit value of the outlet side temperature based on the outside air temperature; The lower limit value of the flow rate is R1, the correction coefficient at R1 is α1, The rated value of the flow rate is R2, the correction coefficient for R2 is α2, When the upper limit value of the flow rate is R3 and the correction coefficient for R3 is α3, α1=α2×R2÷R1, α２＝１、 Let α3 = α2 × R2 ÷ R3, A heating system in which the upper limit value of the outlet side temperature is set by correcting a set temperature based on α1, α2, α3, and the correction value.

2. The control unit is The heating system according to claim 1 , wherein an operating frequency of the compressor is controlled so that the outlet side temperature detected by the outlet temperature sensor does not exceed the set upper limit value of the outlet side temperature.

3. An inlet temperature sensor is further provided to detect an inlet side temperature of the heat medium in the first heat exchanger, The control unit is The heating system according to claim 2 , wherein the operating frequency of the compressor is determined in accordance with the set temperature and the inlet side temperature detected by the inlet temperature sensor.

4. a refrigeration cycle including a compressor, a first heat exchanger, a throttling device, a blower fan, and a second heat exchanger through which outdoor air is ventilated by the blower fan; a pipe joint for connecting the first heat exchanger of the refrigeration cycle to a utilization side device and to an annular medium flow path through which a heat medium is circulated; an outlet temperature sensor for detecting an outlet side temperature of the heat medium in the first heat exchanger; a flow rate detection unit that detects a flow rate of the heat medium circulating through the medium flow path; an outside air temperature sensor for detecting an outside air temperature; a control unit that sets an upper limit value of an outlet side temperature of the heat medium in the first heat exchanger based on the flow rate of the heat medium circulating through the medium flow path detected by the flow rate detection unit and the outside air temperature detected by the outside air temperature sensor, and prevents a discharge pressure of the compressor from exceeding an upper limit value by controlling an operation frequency of the compressor in accordance with the upper limit value of the outlet side temperature, determining a correction value for correcting the upper limit value of the outlet side temperature based on the outside air temperature; The lower limit value of the flow rate is R1, the correction coefficient at R1 is α1, The rated value of the flow rate is R2, the correction coefficient for R2 is α2, When the upper limit value of the flow rate is R3 and the correction coefficient for R3 is α3, α1=α2×R2÷R1, α２＝１、 Let α3 = α2 × R2 ÷ R3, The upper limit value of the outlet side temperature is set by correcting a set temperature based on α1, α2, α3, and the correction value.

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