JPWO2018100729A1 - Refrigeration cycle device - Google Patents

Abstract

The refrigeration cycle apparatus has a heat source unit including a compressor, and a room that exchanges heat between the refrigerant circulating through the air conditioning branch pipe branched from the refrigerant pipe connected to the compressor and the air in the air conditioning target space. , A hot water supply that exchanges heat between the circulating refrigerant and water circulating through a hot water supply branch pipe branched from the refrigerant pipe, a pressure sensor that detects the discharge pressure of the compressor, an indoor unit and a hot water supply Control unit that controls the compressor according to the operating condition of the controller, and the controller controls the discharge pressure of the compressor to a target value when the water heater is operated after stopping the cooling operation of the indoor unit. Is set, and the compressor is controlled such that the discharge pressure detected by the pressure sensor follows the upper limit value.

Description

  The present invention relates to a refrigeration cycle apparatus that performs an air conditioning operation including cooling and heating and a hot water supply operation.

  The conventional air conditioning and hot water supply complex system has, for example, one outdoor unit, a plurality of air conditioning indoor units, and a water heater. The outdoor unit includes a compressor, a four-way valve, an outdoor heat exchanger, and an inverter-controllable control device. Each indoor unit has an indoor heat exchanger, and the water heater has a water heat exchanger. An expansion valve is provided for each of the indoor heat exchanger and the heat exchanger of the water heat exchanger (for example, see Patent Document 1).

  In the air conditioning and hot water supply complex system having the above-described configuration, only one compressor can select either the cooling operation or the heating operation as the operating state of the entire system, but heat exchange between the indoor heat exchanger and the water heat exchanger An expansion valve is provided for each unit. Therefore, in this air conditioning and hot water supply complex system, the cooling operation or heating operation of only one indoor unit, the cooling operation or heating operation of all the indoor units, and the operation of only the water heater as the type of operation. Besides, heating of the indoor unit and simultaneous operation of the water heater can be performed.

JP 2012-78075 A

  In the above-described combined air-conditioning and hot-water supply system, the expansion valve is located downstream of the heat exchanger in both the case where the water heater is operated, the case where the indoor unit is heated, and the case where the indoor unit heating and the water heater simultaneously operate. The refrigerant flows into both the indoor unit heat exchanger and the water heat exchanger. Therefore, when one indoor unit is in heating operation or the water heater is in operation, the high-pressure and high-temperature refrigerant also flows in the stopped indoor unit or the water heater.

  On the other hand, when the indoor unit performs a cooling operation, drain water adheres to the heat exchanger, and drain water is accumulated in the drain pan. When the cooling operation is stopped in this state and the water heater is operated, as described above, the high-pressure and high-temperature refrigerant also flows through the heat exchanger of the indoor unit that is stopped. As a result, the drain water on the surface of the heat exchanger and the drain water accumulated in the drain pan evaporate, and the interior of the indoor unit becomes hot and humid, and as a result, water droplets adhere to members such as the fan and the housing. The size of the water droplet increases as the temperature of the heat exchanger rises, and the water droplet may drop if the gravity of the water droplet is greater than the viscous resistance of the water droplet to the inner wall of the case.

  For example, in the case of a cassette type indoor unit, since the suction port is at the lower part of the housing, water droplets attached to the fan and the inner wall of the housing fall from the suction port. If there is a person under the suction port or a device such as a charged product is placed, water droplets may fall on the person or the device. Even in the air conditioning and hot water supply system disclosed in Patent Document 1, this problem may occur when the heating operation is performed immediately after the cooling operation of the indoor unit is stopped.

  The present invention has been made to solve the above problems, and provides a refrigeration cycle apparatus that prevents water droplets from falling from the indoor unit when the hot water supply operation is performed after stopping the cooling operation of the indoor unit. It is

  A refrigeration cycle apparatus according to the present invention is provided between a heat source unit including a compressor and a refrigerant circulating in an air conditioning branch pipe branched from a refrigerant pipe connected to the compressor and air in a space to be air-conditioned. Pressure sensor for detecting the discharge pressure of the compressor, an indoor unit performing heat exchange in the heat exchanger, a water heater for performing heat exchange between the refrigerant circulating through the hot water supply branch pipe branched from the refrigerant pipe and circulating water, and And a control unit that controls the compressor according to the operating conditions of the indoor unit and the water heater, and the control unit operates the water heater after stopping the cooling operation of the indoor unit. In this case, an upper limit value is set to the target value of the discharge pressure of the compressor, and the compressor is controlled such that the discharge pressure detected by the pressure sensor follows the upper limit value.

  According to the present invention, when the hot water supply operation is performed after stopping the cooling operation of the indoor unit, the control for suppressing the discharge pressure of the compressor is performed to suppress the high temperature refrigerant from flowing into the indoor unit whose cooling operation is stopped. It is possible to prevent the interior of the casing of the indoor unit from becoming hot and humid, and to prevent water droplets from falling from the indoor unit whose cooling operation is stopped.

It is a conceptual diagram which shows the refrigerant circuit of the air-conditioning / water-heating system in Embodiment 1 of the present invention. It is sectional drawing which shows the internal structure of one structural example of the indoor unit shown in FIG. It is a block diagram which shows one structural example of the control part shown in FIG. It is a flowchart which shows the procedure which determines the control flag regarding control of a compressor about the control method in Embodiment 1 of this invention. It is a flowchart which shows the procedure of the operation | movement based on the control flag determined in FIG. 4 about the control method in Embodiment 1 of this invention. It is a conceptual diagram which shows the refrigerant circuit of the air-conditioning / water-heating system in Embodiment 2 of this invention. It is a graph which shows transition of the discharge pressure and operating frequency of a compressor, the temperature of the water in a tank, and the state of the power supply of a heater in, when the water heater shown in FIG. 6 performs boiling operation. It is a flowchart which shows the procedure of the operation | movement based on the control flag determined in FIG. 4 about the control method in Embodiment 2 of this invention. It is a block diagram which shows an example of the structure electrically connected to the control part shown in FIG.

Embodiment 1
The configuration of the combined air-conditioning and hot-water supply system according to the first embodiment will be described. FIG. 1 is a conceptual diagram showing a refrigerant circuit of the combined air-conditioning and hot water supply system according to Embodiment 1 of the present invention. FIG. 2 is a cross-sectional view showing an internal structure of one configuration example of the indoor unit shown in FIG. Although FIG. 2 shows the case where the indoor units 302a and 302b shown in FIG. 1 are cassette type indoor units, the indoor units 302a and 302b are not limited to the cassette type indoor units. FIG. 2 shows a half sectional structure of the indoor unit 302a.

  As shown in FIG. 1, the combined air-conditioning and hot-water supply system 100 includes a heat source unit 301, indoor units 302a and 302b for conditioning the space to be air-conditioned, and a water heater 303. A heating device 304 is connected to the water heater 303. A branch unit 305 is provided between the indoor units 302 a and 302 b and the water heater 303 and the heat source unit 301. Although FIG. 1 shows the case where there are two indoor units, one indoor unit may be used, or three or more indoor units may be used.

  The heat source unit 301 includes a compressor 11, a heat exchanger 12, a blower 13, a four-way valve 14, a control unit 15, a throttling unit 16, and an accumulator 10. The compressor 11, the four-way valve 14, and the heat exchanger 12 are connected by a refrigerant pipe 17. In the refrigerant pipe 17, a pressure sensor 18 for detecting the discharge pressure of the refrigerant is provided on the discharge port side of the compressor 11. The compressor 11, the blower 13, the four-way valve 14, and the pressure sensor 18 are connected to the control unit 15 via a signal line.

  The compressor 11 compresses and discharges the refrigerant to be sucked. The blower 13 supplies outside air to the heat exchanger 12. The heat exchanger 12 exchanges heat between the refrigerant and the outside air. The four-way valve 14 switches the flow path of the refrigerant. The pressure sensor 18 outputs the value of the discharge pressure to be detected to the control unit 15.

  The branch unit 305 has expansion valves 51a to 51c. The expansion valves 51 a to 51 c are provided in the air conditioning branch pipes 17 a and 17 b and the hot water supply branch pipe 17 c in which the refrigerant pipe 17 extending from the throttling portion 16 of the heat source unit 301 is branched. The air conditioning branch pipes 17a and 17b return to the branch unit 305 through the indoor units 302a and 302b. The hot water supply branch pipe 17 c returns to the branch unit 305 through the water heater 303. In the branch unit 305, the air conditioning branch pipes 17a and 17b extending from the indoor units 302a and 302b merge with the hot water supply branch pipe 17c extending from the water heater 303, and are connected to the four-way valve 14 side of the refrigerant pipe 17. The expansion valves 51a to 51c are connected to the control unit 15 via signal lines.

  The indoor unit 302a has a heat exchanger 21a and a blower 22a. The indoor unit 302b has a heat exchanger 21b and a blower 22b. The heat exchanger 21a is connected to the air conditioning branch pipe 17a. The heat exchanger 21b is connected to the air conditioning branch pipe 17b. As shown in FIG. 2, the indoor unit 302a is provided with a drain pan 23a for storing drain water condensed on the surface of the heat exchanger 21a in the direction of gravity of the heat exchanger 21a. The indoor unit 302b is also provided with a drain pan (not shown) in the gravity direction of the heat exchanger 21b.

  FIG. 2 shows that the drain water 61 adheres to the surface of the heat exchanger 21a when the indoor unit 302a performs the cooling operation. Further, FIG. 2 shows that the drain water 61 attached to the surface of the heat exchanger 21a falls and the drain water 62 is accumulated in the drain pan 23a.

  The blower 22a shown in FIG. 1 sucks the air of the space to be air-conditioned into the indoor unit 302a and supplies it to the heat exchanger 21a. The blower 22b shown in FIG. 1 sucks the air of the space to be air-conditioned into the indoor unit 302b and supplies it to the heat exchanger 21b. The heat exchangers 21a and 21b exchange heat between the air in the space to be air-conditioned and the refrigerant. The blowers 22a and 22b are connected to the control unit 15 via a signal line.

  The water heater 303 has a heat exchanger 31, a heat exchanger 33, a three-way valve 39, pumps 34, 35 and a tank 36. The heat exchanger 31, the heat exchanger 33, and the pump 34 are connected in order, and a primary water circuit 37 in which water circulates through these devices is configured. The primary water circuit 37 is an example of a fluid circuit. Further, the heat exchanger 33, the pump 35 and the tank 36 are connected in order, and a secondary water circuit 38 in which water circulates through these devices is configured. The secondary water circuit 38 is an example of a water circuit. The tank 36 is supplied with tap water from the outside. Further, the tank 36 is connected to a shower or the like in which the hot water after heat exchange is used. The heat exchanger 31 exchanges heat between the water circulating in the primary water circuit 37 and the refrigerant passing through the hot water supply branch pipe 17c. The heat exchanger 33 exchanges heat between the water circulating in the primary water circuit 37 and the water in the tank 36.

  In the primary water circuit 37, a three-way valve 39 is provided between the heat exchanger 31 and the heat exchanger 33. The primary water circuit 37 is branched from the three-way valve 39, connected to a heating device 304 in the middle, and connected to a heating circuit 41 which joins the junction 40 of the heat exchanger 33 and the pump 34. The three-way valve 39 and the pumps 34, 35 are connected to the control unit 15 via signal lines.

  FIG. 3 is a block diagram showing one configuration example of the control unit shown in FIG. The control unit 15 has a memory 151 for storing a program, a central processing unit (CPU) 152 for executing processing according to the program, and a timer 153 for measuring time. The control unit 15 is, for example, a microcomputer. The control unit 15 starts and stops the compressor 11 and the blowers 13, 22a, 22b and the operation frequency of the four-way valve 14 according to the operation instruction to the indoor units 302a, 302b and the operation state of the indoor units 302a, 302b. It controls the flow path switching and the opening degree of the throttle portion 16 and the expansion valves 51a, 51b. Further, the control unit 15 switches the flow path of the three-way valve 39, starts and stops the pumps 34 and 35, the throttling unit 16 and the expansion valve according to the operation instruction to the water heater 303 and the operation state of the water heater 303. Control the opening degree of 51c. A temperature sensor (not shown) for detecting the indoor temperature may be provided to the indoor units 302a and 302b. In this case, the control unit 15 may control the compressor 11, the blowers 13, 22a, 22b, the throttling unit 16, and the expansion valves 51a, 51b such that the indoor temperature becomes the set temperature.

  As shown in FIG. 1, with the heat source unit 301, the indoor units 302a and 302b, and the water heater 303 connected, the heat source unit 301 and the indoor units 302a and 302b, and the heat source unit 301 and the water heater 303 are respectively frozen. A cycle is configured. The solid-line arrow shown in FIG. 1 shows the flow of the refrigerant when the water heater 303 is operating. The broken arrows indicate the flow of water in the water heater 303. In FIG. 1, the case where hot water is circulated also to the heating device 304 is shown.

  Next, the operation of the combined air-conditioning and hot-water supply system 100 shown in FIG. 1 will be described. FIG. 4 is a flowchart showing a procedure of determining a control flag related to control of a compressor in the control method according to the first embodiment of the present invention.

  In the air conditioning and hot water supply complex system 100 shown in FIG. 1, when an operation instruction is input to one or both of the indoor unit 302a and the indoor unit 302b, the control unit 15 instructs the indoor units 302a and 302b. In accordance with the operating condition, it is determined which of the cooling application and the heating application the compressor 11 is operated. The cooling application is a case where one or both of the indoor unit 302a and the indoor unit 302b are in a cooling operation. The heating application includes the case where the water heater 303 operates in addition to the case where one or both of the indoor unit 302a and the indoor unit 302b are in the heating operation. In addition, the memory 151 stores information of a control flag indicating whether control to limit the discharge pressure of the compressor 11 is performed. In the control flag, an invalid state in which the discharge pressure is not limited is set as an initial value.

  In step S1 shown in FIG. 4, the control unit 15 determines which of heating and cooling the compressor 11 is operating. If the control unit 15 determines that the compressor 11 is in operation for cooling, the control unit 15 proceeds to step S3 and updates the control flag to the valid state. On the other hand, when the control unit 15 determines in step S1 that the compressor 11 is operating for heating, the process proceeds to step S2. In step S2, the control unit 15 starts the timer 153, and measures the operating time Tw which is the cumulative time that the compressor 11 operates in the heating application after stopping the operation in the cooling application.

  When the control flag is set to the valid state in step S3, the control unit 15 sets the value of the operating time Tw to 0 in step S4. In step S5, the control unit 15 compares the operating time Tw with the lower limit Twlim of the operating time for heating. If the operation time Tw is equal to or more than the lower limit value Twlim, the control unit 15 proceeds to step S6 and updates the control flag to an invalid state. In step S5, when the operation time Tw is less than the lower limit value Twlim, the control unit 15 returns to step S1.

  As described with reference to FIG. 4, the control flag is set to the valid state or the invalid state according to the application of the compressor 11 and the operation time Tw. If the compressor 11 is in the cooling operation, the control flag is set to the valid state. In addition, when the compressor 11 is switched from the cooling application to the operation of the heating application, if the operation time of the heating application is less than a predetermined time, the control flag maintains the valid state and the operation time of the heating application is previously The control flag is set to an invalid state if a predetermined time or more has elapsed. When the control flag is in the valid state, the control unit 15 sets an upper limit value to the target value of the discharge pressure of the compressor 11 and controls the compressor 11 so that the discharge pressure follows the upper limit value. When the control flag is in the invalid state, the control unit 15 does not limit the discharge pressure of the compressor 11.

  Here, let us consider the state inside the housings of the indoor units 302a and 302b immediately after the cooling operations are stopped after the indoor units 302a and 302b perform the cooling operation. As illustrated in FIG. 2, the drain water 61 adheres to the heat exchanger 21 a and the drain water 62 is accumulated in the drain pan 23 a as shown in FIG. 2. The inside of the housing of the indoor unit 302b is also in the same state as the indoor unit 302a.

  Next, the operation of the combined air-conditioning and hot-water supply system 100 will be described when the water heater 303 starts operation from the state as shown in FIG. 2 after the indoor units 302a and 302b stop. FIG. 5 is a flow chart showing the procedure of the operation based on the control flag determined in FIG. 4 for the control method in the first embodiment of the present invention. The memory 151 stores the limit value Pdmlim of the target value of the discharge pressure of the compressor 11.

  In step S7, the control unit 15 determines the state of the control flag set in the procedure shown in FIG. If the state of the control flag is valid, the control unit 15 proceeds to step S8 and compares the target discharge pressure Pdm with the limit value Pdmlim. In step S8, when the target discharge pressure Pdm is larger than the limit value Pdmlim, the control unit 15 proceeds to step S9 and updates the target discharge pressure Pdm to the limit value Pdmlim. On the other hand, when the target discharge pressure Pdm is less than or equal to the limit value Pdmlim in step S8, the control unit 15 proceeds to step S10 and does not correct the target discharge pressure Pdm. By the steps S8 to S10, when the control flag is in the valid state, it is possible to limit the target discharge pressure to a predetermined limit value or less.

  Further, as a result of the determination in step S7, when the control flag is in the invalid state, the control unit 15 does not correct the target discharge pressure Pdm. In this way, it is possible to limit the target discharge pressure Pdm only when control regarding the restriction of the discharge pressure is required, that is, only when the control flag is in the valid state.

  When the control unit 15 determines the target discharge pressure Pdm in any of step S9, step S10 and step S12, the discharge pressure Pd is calculated using the values of the discharge pressure Pd detected by the pressure sensor 18 and the target discharge pressure Pdm. The operating frequency of the compressor 11 is controlled to follow the target discharge pressure Pdm (step S11).

  The effect of the control method described above will be described with reference to FIGS. 1 and 2. When the indoor unit 302b stops the operation and the indoor unit 302a performs the cooling operation, the heat exchanger 21a functions as an evaporator, and as shown in FIG. 2, drain water 61 is formed on the surface of the heat exchanger 21a. Adheres, and drain water 62 is accumulated in the drain pan 23a. From this state, when the operation of the indoor unit 302a is stopped and the operation of the water heater 303 is started, the control unit 15 switches the flow path of the four-way valve 14 by making the expansion valve 51a fully closed. Specifically, the control unit 15 controls the four-way valve 14 so that the refrigerant discharged from the compressor 11 flows into the hot water supply branch pipe 17 c via the four-way valve 14. As a result, the high pressure and high temperature refrigerant discharged from the compressor 11 flows from the refrigerant pipe 17 to the heat exchanger 31 via the hot water supply branch pipe 17 c.

  When the high pressure / high temperature refrigerant flows from the four-way valve 14 side into the hot water supply branch pipe 17c, a part of the refrigerant also flows into the air conditioning branch pipe 17a. When control to limit the discharge pressure Pd of the compressor 11 is not performed, the high-pressure and high-temperature refrigerant raises the temperature of the heat exchanger 21a to promote evaporation of the drain water 61 and 62, and the inside of the casing becomes high temperature and high humidity As a result, water droplets adhere to the inner wall of the case. In the first embodiment, the control unit 15 controls the operating frequency of the compressor 11 so that the discharge pressure Pd of the compressor 11 follows the limit value Pdmlim, which is lower than the normal target discharge pressure Pdm, as necessary. Thus, an excessive temperature rise of the heat exchanger 21a can be prevented. As a result, excessive evaporation of the drain waters 61 and 62 is suppressed, and the inside of the casing can be prevented from being in a high temperature and high humidity state and water droplets adhering to the inside wall of the casing.

  The combined air-conditioning and hot-water supply system 100 of the first embodiment circulates the heat-source unit 301 including the compressor 11 and the air-conditioning branch pipes 17 a and 17 b branched from the refrigerant pipe 17 connected to the compressor 11. Hot water supply for heat exchange between refrigerant and water circulating through indoor unit 302a, 302b for heat exchange between the refrigerant and air in the air conditioning target space, and the hot water supply branch pipe 17c branched from the refrigerant pipe 17 , A pressure sensor 18 for detecting the discharge pressure of the compressor 11, and a control unit 15 for controlling the refrigeration cycle for circulating the refrigerant, the control unit 15 stopping the cooling operation of the indoor units 302a and 302b When the water heater 303 is operated after the operation, the upper limit value is set to the target value of the discharge pressure of the compressor 11, and the discharge pressure detected by the pressure sensor 18 is compressed to a pressure lower than normal. It is intended to control the 11.

  According to the first embodiment, the control unit 15 stops the operation after performing the cooling operation of one or both of the indoor units 302a and 302b, and starts the operation of the water heater 303. The discharge pressure of the machine 11 is suppressed to a pressure lower than normal. Therefore, it is suppressed that the temperature of the refrigerant flowing into the water heater 303 becomes too high, and even if a part of the refrigerant flows into the air conditioning branch piping 17a, 17b of the stopped indoor units 302a, 302b, the heat exchanger The temperature of 21a, 21b is prevented from rising excessively and excessive evaporation of the drain water 61, 62 is suppressed. As a result, the inside of the case is in a high temperature and high humidity state, and the water droplets are prevented from adhering to the inner wall of the case, and the adhered water droplets can be prevented from falling from the suction ports of the indoor units 302a and 302b.

  In the first embodiment, the control unit 15 discharges the compressor 11 when the operation time Tw of the compressor 11 is equal to or less than a predetermined lower limit value Twlim after stopping the cooling operation of the indoor units 302a and 320b. The upper limit value of pressure may be set. When the operation time Tw is equal to or less than the lower limit value Twlim, water droplets may adhere to the inner wall of the indoor unit 302a, 302b, but this can be prevented. On the other hand, when the operation time Tw is larger than the lower limit value Twlim, the discharge pressure of the compressor 11 is not limited, so that the boiling time of the water heater 303 can be quickened.

  In the first embodiment, the operating time Tw used to determine whether to set the upper limit value to the target value of the discharge pressure is the heating time including the case where the control unit 15 performs the heating operation of the indoor units 302a and 302b. It may be time to operate the compressor 11 in the application. In this case, also when the indoor units 302a and 302b stop the cooling operation and then switch to the simultaneous operation of the heating operation and the hot water supply operation of the indoor units 302a and 302b, the generation of water droplets is suppressed in the housing of the indoor units. Can.

Second Embodiment
As described in the first embodiment, when the target value of the discharge pressure of the compressor 11 is set to the upper limit value, for example, when the water heater 303 performs a boiling operation for a shower application, the boiling time becomes long. There is a case. In the second embodiment, the water heater 303 is provided with a heater to suppress an increase in boiling time.

  The configuration of the combined air-conditioning and hot-water supply system according to the second embodiment will be described. In the second embodiment, the same components as those of the first embodiment are designated by the same reference numerals and their detailed description will be omitted.

  FIG. 6 is a conceptual diagram showing a refrigerant circuit of the combined air-conditioning and hot water supply system according to Embodiment 2 of the present invention. As shown in FIG. 6, the water heater 303 has a heater 32. In the primary water circuit 37, the heater 32 is provided between the three-way valve 39 and the heat exchanger 31. A power supply (not shown) that supplies power to the heater 32 is connected to the heater 32. The control unit 15 is connected to the power supply of the heater 32 via a signal line. When an instruction to start the operation of water heater 303 is input from the user in a state where the upper limit value is set to the target value of the discharge pressure of compressor 11, control unit 15 controls power on / off of heater 32. Do.

  Next, the operation of the combined air-conditioning and hot-water supply system 100 according to the second embodiment will be described with reference to FIGS. 7 and 8. FIG. 7 is a graph showing transition of the discharge pressure and operating frequency of the compressor, the temperature of water in the tank, and the state of the power supply of the heater when the water heater shown in FIG. 6 performs the boiling operation. is there.

  The horizontal axes of the four graphs shown in FIG. 7 are time. The vertical axis of the top graph among the four graphs indicates the change of the discharge pressure Pd of the compressor 11. This graph is referred to as a discharge pressure graph. The vertical axis of the second graph from the top among the four graphs indicates the change of the operating frequency F of the compressor 11. This graph is called a frequency graph. Of the four graphs, the vertical axis of the second graph from the bottom indicates the change in the water temperature Ttank of the tank 36. This graph is called a water temperature graph. Of the four graphs, the vertical axis of the lowermost graph indicates changes in the on and off states of the heater 32. This graph is called a heater state graph. The target temperature of the water temperature of the tank 36 is denoted as Tref.

  FIG. 8 is a flow chart showing the procedure of the operation based on the control flag determined in FIG. 4 in the control method in the second embodiment of the present invention. Of the procedures shown in FIG. 8, steps S7 to S12 are similar to the operations described with reference to FIG. 5, and thus detailed description thereof is omitted. The memory 151 shown in FIG. 3 stores a lower limit frequency Fmin which is a lower limit value of the operating frequency F of the compressor 11.

  In step S11, immediately after the start of boiling, the control unit 15 increases the operating frequency F of the compressor 11 to control the compressor 11 so that the discharge pressure Pd matches the target discharge pressure Pdm. After that, the operating frequency F of the compressor 11 increases or decreases so that the discharge pressure Pd is stabilized at the target discharge pressure Pdm. However, as shown in the water temperature graph of FIG. 7, as the water temperature Ttank rises, the temperature of water entering the heat exchanger 31 rises, and if the operating frequency F is not lowered, the discharge pressure Pd rises. Therefore, the operating frequency F of the compressor 11 gradually decreases and finally sticks to the lower limit frequency Fmin.

  The state in which the operating frequency F of the compressor 11 is stuck to the lower limit frequency Fmin indicates that the amount of heat supplied from the heat source unit 301 is insufficient, and operating for a long time in this state extends the boiling time Lead to

  Therefore, in step S13, the control unit 15 determines whether the discharge pressure Pd is equal to or higher than the target discharge pressure Pdm. If the discharge pressure Pd is smaller than the target discharge pressure Pdm, the control unit 15 returns to step S7. In step S13, when the discharge pressure Pd is equal to or higher than the target discharge pressure Pdm, the control unit 15 proceeds to step S14 and determines whether the operating frequency F is equal to the lower limit frequency Fmin. If the operating frequency F is not equal to the lower limit frequency Fmin, the control unit 15 returns to step S7. In step S14, when the operating frequency F is equal to the lower limit frequency Fmin, the control unit 15 proceeds to step S15 and stops the compressor 11. Subsequently, in step S16, the control unit 15 turns on the power supply of the heater 32 to start power supply to the heater 32.

  Subsequently, in step S16, the control unit 15 maintains the power supply of the heater 32 in the ON state until the water temperature Ttank becomes equal to or higher than the target temperature Tref. When the water temperature Ttank becomes equal to or higher than the target temperature Tref, the control unit 15 proceeds to step S17 and turns off the heater 32 to stop the power supply to the heater 32.

  As described above, the control unit 15 switches the operation and stop of the compressor 11 and switches the power supply and the power supply stop to the heater 32 based on the discharge pressure Pd of the compressor 11 and the operating frequency F. Is going. For example, in steps S13 to S16 shown in FIG. 8, the control unit 15 performs compression from a state in which the compressor 11 is operated but power is not supplied to the heater 32 based on the discharge pressure Pd and the operating frequency F of the compressor 11 The operation of the machine 11 is stopped to switch the state of supplying power to the heater 32. Further, when returning to step S7 in the determination of step S13 and step S14, the control unit 15 operates the compressor 11 without supplying power to the heater 32 based on the discharge pressure Pd or the operating frequency F of the compressor 11. It will be selected.

  Further, in step S15 of the flowchart shown in FIG. 8, the control unit 15 may proceed to step S16 and start the power supply to the heater 32 while the operation of the compressor 11 is continued. In this case, the heat exchanger 31 can use both the heat obtained in the refrigeration cycle and the heat generated by the heater 32. If power is supplied to the heater 32 while the compressor 11 is operated, the power consumption increases, but the boiling time can be shortened compared to the case where power is supplied to the heater 32 by stopping the compressor 11 . On the other hand, when the operation of the compressor 11 is continued in step S15, for example, when the coefficient of performance (coefficient of performance) significantly decreases, the control unit 15 stops the compressor 11 and performs the power supply to the heater 32. It is also good.

  In the second embodiment, when the hot water supply operation is started after the cooling operation of any one or both of the indoor units 302a and 302b is stopped, the control unit 15 not only suppresses the discharge pressure of the compressor 11, but Based on the discharge pressure Pd of the compressor 11 and the operating frequency F, switching of the operation and stop of the compressor 11 and switching of the power supply of the heater 32 are performed. Therefore, not only an effect similar to that of the first embodiment can be obtained, but also, it can be suppressed that the boiling time in water heater 303 becomes long. Since the control unit 15 switches the operation based on the discharge pressure Pd of the compressor 11 and the operating frequency F, it is not necessary to newly provide a sensor.

  In the flowchart shown in FIG. 8, the control unit 15 determines the switching between the operation and stop of the compressor 11 and the switching of the power supply of the heater 32 on and off, the discharge pressure Pd of the compressor 11 and the operating frequency Although it carries out on the basis of F, it may carry out on the basis of the amount of heat of heat exchanger 31. In this case, since the control unit 15 switches the operation based on the amount of heat actually required, the effect of suppressing an increase in the boiling time is improved. The heat quantity of the heat exchanger 31 can be calculated, for example, from the difference between the temperature of water entering the heat exchanger 31 and the temperature of water exiting the heat exchanger 31, and the water flow rate of the pump 34. An example will be described below.

  FIG. 9 is a block diagram showing an example of a configuration electrically connected to the control unit shown in FIG. As shown in FIG. 6, the control unit 15 is connected to the heater 32, the incoming water temperature sensor 42, the outgoing water temperature sensor 43, and the flow rate sensor 44 via a signal line in addition to the device shown in FIG. 3. The incoming water temperature sensor 42 and the flow rate sensor 44 are provided between the pump 34 and the heat exchanger 31. The water temperature sensor 43 is provided between the heat exchanger 31 and the three-way valve 39. The incoming water temperature sensor 42 detects the temperature of water flowing into the heat exchanger 31 as the incoming water temperature. The water temperature sensor 43 detects the temperature of the water flowing out of the heat exchanger 31 as the water temperature. The flow rate sensor 44 detects the flow rate of water discharged from the pump 34 and flowing into the heat exchanger 31.

Heat quantity per unit time Q [J / min], density of water ρ [g / cm ³ ], flow rate per unit time L [cm ³ / min], temperature difference between the incoming water temperature Tin and the outgoing water temperature Tout Is ΔT [K], and the specific heat of water is C [J / g · K]. The heat amount Q is calculated by the following equation (1).
Q = ρ × L × C × ΔT (1)

  The memory 151 stores the density 水 of water and the specific heat C, and the equation (1). Further, the memory 151 records, for the calculated heat quantity Q, a threshold that determines the operation and stop of the compressor 11 and the power supply to the heater 32 and the stop thereof. For example, the memory 151 includes a first threshold that determines whether to use both the compressor 11 and the heater 32, and a second threshold that determines which of the compressor 11 and the heater 32 to use. I remember. In addition, the control part 15 may change the threshold value which the memory 151 memorize | stores according to the setting temperature which a user inputs about hot water which a user uses by a shower etc., for example.

  The operation of the control unit 15 shown in FIG. 9 will be described. The control unit 15 calculates a temperature difference ΔT from the water temperature Tout received from the water temperature sensor 43 and the water temperature Tin received from the water temperature sensor 42. Then, the control unit 15 substitutes the flow rate L received from the flow rate sensor 44 and the temperature difference ΔT into the equation (1) to calculate the heat quantity Q. Furthermore, the control unit 15 compares the calculated heat quantity Q with the threshold value stored in the memory 151. If the heat amount Q is less than the first threshold value, the boiling time may be long, so the control unit 15 performs both the operation of the compressor 11 and the power supply to the heater 32. When the heat quantity Q is equal to or more than the first threshold and less than the second threshold, the heater 32 can obtain sufficient heat for boiling, so the control unit 15 stops the compressor 11 and supplies power to the heater 32. I do. When the heat quantity Q is equal to or higher than the second threshold value, the refrigeration cycle by the operation of the compressor 11 provides sufficient heat for boiling, so the control unit 15 does not supply power to the heater 32 and operates the compressor 11. I do.

  In the second embodiment, the judgment criteria for switching between the operation and stop of the compressor 11 and for switching the power supply to the heater 32 and the stop thereof are the discharge pressure and operating frequency of the compressor 11 and the heat exchanger 31. It is not limited to the amount of heat exchanged and the coefficient of performance of the refrigeration cycle. The control unit 15 may perform switching of operation and stop of the compressor 11 and switching of power supply to the heater 32 and power supply stop on the basis of the state of the refrigeration cycle including these determination criteria.

  The first and second embodiments have been described above in the case where the refrigeration cycle apparatus is an air conditioning and hot water supply combined system as an embodiment of the refrigeration cycle apparatus that performs air conditioning operation including cooling and heating and hot water supply operation. It is not limited to what was demonstrated in said Embodiment 1 and 2.

  For example, in step S2 shown in FIG. 4, the control unit 15 measures the operation time Tw of the heating application of the compressor 11 after the cooling operation is stopped, but among the plurality of indoor units included in the combined air conditioning and hot water supply system, The operating times Tw of all the indoor units that have stopped the cooling operation may be measured. In this case, the control unit 15 may adopt the minimum value among the plurality of operation times Tw as the operation time Tw serving as a determination reference of whether to set the upper limit value to the compressor 11. Thus, it is possible to determine the necessity of the discharge pressure control of the compressor 11 from the operating state of each indoor unit, which can not be obtained based on the operating time focusing on one compressor 11 it can. As a result, even if the plurality of indoor units stop the cooling operation at different times, it is possible to more reliably obtain the water droplet falling prevention effect.

  Further, the heating application of the compressor 11 is applied not only to the boiling operation in the water heater 303 but also to the heating operation of at least one of the indoor units 302a and 302b or the heating operation by the water heater 303 using the heating device 304. be able to.

  Reference Signs List 10 accumulator, 11 compressor, 12 heat exchanger, 13 blower, 14 four-way valve, 15 control unit, 16 throttle unit, 17 refrigerant piping, 17a, 17b branch piping for air conditioning, 17c branch piping for hot water supply, 18 pressure sensor, 21a , 21b heat exchanger, 22a, 22b blower, 23a drain pan, 31, 33 heat exchanger, 32 heater, 34, 35 pump, 36 tank, 37 primary water circuit, 38 secondary water circuit, 39 three-way valve, 40 merging Points, 41 heating circuit, 42 inlet temperature sensor, 43 outlet temperature sensor, 44 flow sensor, 51a to 51c expansion valve, 61, 62 drain water, 100 air conditioning and hot water supply combined system, 151 memory, 152 CPU, 153 timer, 301 heat source unit , 302a, 302b indoor unit, 303 water heater, 304 heating system, 05 branch unit.

A refrigeration cycle apparatus according to the present invention is provided between a heat source unit including a compressor and a refrigerant circulating in an air conditioning branch pipe branched from a refrigerant pipe connected to the compressor and air in a space to be air-conditioned. A plurality of indoor units exchanging heat with each other, a hot water supply exchanging heat between refrigerant circulating through the hot water supply branch pipe branched from the refrigerant pipe and circulating, and detecting the discharge pressure of the compressor A pressure sensor, and a control unit configured to control the compressor in accordance with the operating conditions of the plurality of indoor units and the water heater, the control unit being configured to perform a cooling operation of the plurality of indoor units; When the water heater is operated after stopping the cooling operation of the machine, the upper limit value is set to the target value of the discharge pressure of the compressor, and the discharge pressure detected by the pressure sensor follows the upper limit. and control of the compressor, the cooling operation the chamber The upper limit value is set when the operation time which is the cumulative time of the operation of the compressor after stopping the cooling operation of the machine is equal to or less than a predetermined time, and the operation time of the indoor unit operated for the cooling operation is set. And the minimum value is used as a criterion for setting the upper limit value .

Claims (8)

A heat source unit including a compressor,
An indoor unit that exchanges heat between a refrigerant circulating in an air conditioning branch pipe branched from a refrigerant pipe connected to the compressor and circulating in the air-conditioned space;
A water heater that exchanges heat between a circulating refrigerant and water that circulates through a hot water supply branch pipe branched from the refrigerant pipe;
A pressure sensor for detecting the discharge pressure of the compressor;
A control unit configured to control the compressor in accordance with the operating conditions of the indoor unit and the water heater;
The control unit
When the water heater is operated after stopping the cooling operation of the indoor unit, an upper limit value is set to the target value of the discharge pressure of the compressor, and the discharge pressure detected by the pressure sensor follows the upper limit And a refrigeration cycle apparatus for controlling the compressor. The control unit
The refrigeration cycle apparatus according to claim 1, wherein the upper limit value is set when an operation time which is an accumulated time of the operation of the compressor after stopping the cooling operation of the indoor unit is equal to or less than a predetermined time.   The refrigeration cycle apparatus according to claim 2, wherein the operation time is a time during which the control unit operates the compressor in a heating application including a case of heating the indoor unit. A plurality of the indoor units are provided,
The control unit
The refrigeration cycle apparatus according to claim 2 or 3, wherein a minimum value of the operation time of the indoor unit performing the cooling operation among the plurality of indoor units is used as a determination reference of the setting of the upper limit value. The water heater is provided with a heater,
The control unit
After control of the compressor is started so that the discharge pressure follows the upper limit value, switching of the operation and stop of the compressor based on the state of the refrigeration cycle, power supply and power supply to the heater The refrigeration cycle apparatus according to any one of claims 1 to 4, which performs stop switching.   The refrigeration cycle apparatus according to claim 5, wherein the state of the refrigeration cycle is a discharge pressure and an operating frequency of the compressor.   The refrigeration cycle apparatus according to claim 5, wherein the state of the refrigeration cycle is a heat quantity that is heat-exchanged by a heat exchanger provided in the water heater. An incoming water temperature sensor that detects the temperature of water flowing into the heat exchanger;
A water temperature sensor for detecting the temperature of water flowing out of the heat exchanger;
And a flow rate sensor for detecting the flow rate of water flowing into the heat exchanger.
The control unit
The refrigeration according to claim 7, wherein the heat quantity of the heat exchanger is calculated using the temperature detected by the water temperature sensor, the temperature detected by the water temperature sensor, and the flow rate detected by the flow rate sensor. Cycle equipment.

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