JP2017036882A - Heat pump system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat pump system capable of securely preventing freezing and breakage of a water heat exchanger during a reverse cycle type defrosting operation and of preventing heat loss from being generated on a water circuit side.SOLUTION: A heat pump system includes: a refrigerant circuit 42 in a first system that is constituted by connecting a first utilization unit 3 having a utilization side heat exchanger 28 and a second utilization unit 4 having a water heat exchanger 35 for generating hot water to a heat source unit 2 having a heat source side heat exchanger 7 in parallel; and defrosting control means 45 for switching the refrigerant circuit 42 from a heating cycle to a cooling cycle by using a four-way selector valve 6 for defrosting when frost forms on the heat source side heat exchanger 7. The defrosting control means 45 includes means 33, 34 for blocking a flow of a refrigerant to the water heat exchanger 35 of the second utilization unit 4 and making the refrigerant flow only on the utilization side heat exchanger 28 side of the first utilization unit 3 during a defrosting operation.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a heat pump system provided with a unit that heats or cools indoor air by heat exchange with a refrigerant to cool and heat, and a unit that generates hot water for hot water supply or heating by heat exchange with a refrigerant. Is.

  Patent Documents 1, 2 and the like are disclosed as heat pump systems capable of generating hot water for hot water supply or heating by exchanging heat with a refrigerant at the same time as indoor air is heated or cooled by heat exchange with the refrigerant. As shown in Fig. 4, a direct expansion type use side heat for exchanging heat between the refrigerant and room air is used for a heat source unit including a compressor, a four-way switching valve, and a heat source side heat exchanger for exchanging heat between the refrigerant and outside air. A first usage unit having an exchanger is connected in parallel with a second usage unit having a direct expansion water heat exchanger that exchanges heat between refrigerant and water and generates hot water for hot water supply or heating. 2. Description of the Related Art A heat pump system that configures a single refrigerant circuit (heat pump cycle) is known.

  In such a heat pump system, during operation in a heating cycle, that is, in operation in a hot water generation operation mode for generating hot water or hot water for heating, heating operation mode, hot water generation / heating operation mode, etc., outside air on the heat source unit side It is known that the heat source side heat exchanger that exchanges heat with the frost forms. And when it is detected that the heat source side heat exchanger has formed frost, in order to remove the frost (defrost), the refrigerant circuit is switched from the heating cycle to the cooling cycle by a four-way switching valve, so-called reverse cycle. System defrost control means is adopted.

  In the above Patent Documents 1 and 2, in a system employing reverse cycle defrost control means, the temperature of the water circulated to the water heat exchanger of the second usage unit is equal to or higher than a predetermined temperature during the defrost operation. In addition, the refrigerant is passed through only the water heat exchanger of the second usage unit or both of the water heat exchanger of the second usage unit and the usage side heat exchanger of the first usage unit to defrost the water side temperature. Is disclosed in which the refrigerant to the water heat exchanger is shut off and the refrigerant is switched to flow only to the use side heat exchanger of the first usage unit when the temperature drops below a predetermined temperature. In other words, an air heat source heat pump system incorporating a water heat exchanger employs a logic defrosting method different from that of a normal air to air heat pump system in order to prevent water freezing in the water heat exchanger. .

JP 2006-46692 A JP 2010-196950 A

  In the heat pump system described above, frost is generated in the heat source side heat exchanger of the heat source unit when operated in the heating cycle as in the warm water generation operation mode, the heating operation mode, and the warm water generation / heating operation mode. At this time, the defrosting by flowing the low-pressure refrigerant to the water heat exchanger of the second usage unit is performed by removing heat from the hot water on the water circuit side connected to the water heat exchanger and performing the defrosting operation. This is to shorten the frost operation time.

  However, since the defrosting operation is normally performed at the maximum number of rotations of the compressor, the low-pressure pressure is suddenly reduced at the moment of switching to the defrosting operation, and the low-pressure tends to be lower. Due to the endothermic action, the temperature of the hot water on the water circuit side is lowered, and there is a risk that the water will freeze in the water heat exchanger, resulting in a risk of damage to the water heat exchanger. In particular, when the water heat exchanger is a plate heat exchanger, the joint between the plates tends to come off, and the risk of breakage tends to increase.

  For this reason, as described above, the temperature on the water circuit side is monitored, and when the temperature drops below a predetermined temperature, the refrigerant to the water heat exchanger is shut off, and only the usage side heat exchanger of the first usage unit is shut off. Therefore, the control system has become complicated. In addition, during defrosting, the defrosting operation time can be shortened by defrosting using the endothermic heat from the hot water, but the temperature of the hot water is lowered. When returning to the generation / heating operation mode, there was a problem that an operation for covering a heat loss due to a decrease in the temperature of the hot water was required.

  The present invention has been made in view of such circumstances, and can reliably prevent freezing and breakage of the water heat exchanger during reverse cycle defrosting operation, and heat loss on the water circuit side. It aims at providing the heat pump system which can eliminate generation | occurrence | production of this.

In order to solve the above-described problems, the heat pump system of the present invention employs the following means.
That is, the heat pump system according to the present invention includes a compressor, a four-way switching valve, a heat source unit having a heat source side heat exchanger that exchanges heat between the refrigerant and outside air, and a use side heat exchanger that exchanges heat between the refrigerant and room air. A first usage unit, a second usage unit having a water heat exchanger for exchanging heat between the refrigerant and water and generating hot water for hot water supply or heating, and the first usage unit with respect to the heat source unit When the refrigeration occurs on one system refrigerant circuit configured by connecting the second usage units in parallel and the heat source side heat exchanger, the four-way switching valve switches the refrigerant circuit from a heating cycle to a cooling cycle. Defrosting control means for defrosting, wherein the defrosting control means shuts off the refrigerant flow to the water heat exchanger of the second usage unit during the defrosting operation, and Characterized in that it comprises means for flowing the use side heat exchanger side only refrigerant bets.

  According to the present invention, the utilization side heat exchanger of the first utilization unit and the water heat exchanger of the second utilization unit function as a condenser (radiator), and the heat source side heat exchanger of the heat source unit functions as an evaporator. During the operation in the heating operation mode, the hot water generation operation mode, or the hot water generation / heating operation mode, that is, in the operation with the refrigerant circuit in the heating cycle, the heat source side heat exchanger is frosted by the defrost control means When this is detected, the refrigerant circuit is switched from the heating cycle to the cooling cycle to enter the defrosting operation mode. At this time, the refrigerant flow to the water heat exchanger is blocked by the means for blocking the refrigerant flow to the water heat exchanger of the second usage unit, and the refrigerant is circulated only to the usage side heat exchanger of the first usage unit. The high-temperature and high-pressure refrigerant discharged from the compressor is introduced into the heat source side heat exchanger through the four-way switching valve, dissipates heat, melts frost, condenses and liquefies, and then is decompressed to the first usage unit. The defrosting operation is performed by being circulated in the cooling cycle which is led to the use side heat exchanger, evaporated and sucked into the compressor. When the defrosting control means detects the end of defrosting, the heating cycle is switched to return to the original operation mode. Therefore, even if the reverse cycle defrost control means is employed, the low pressure refrigerant does not circulate in the water heat exchanger of the second usage unit during the defrost operation, and the water is frozen in the water heat exchanger, As a result, the risk of damage to the water heat exchanger can be reliably eliminated, and control such as switching the defrosting operation mode by monitoring the water temperature on the water circuit side during the defrosting operation becomes unnecessary. The system can be simplified. Moreover, generation | occurrence | production of the heat loss by utilizing the heat of the hot water by the side of a water circuit at the time of a defrost operation can be eliminated, and energy saving can be aimed at.

  Furthermore, in the heat pump system of the present invention, in the above heat pump system, the means for blocking the refrigerant flow with respect to the water heat exchanger is provided at both or one of the inlets and outlets of the refrigerant circuit connected to the water heat exchanger. It is made into the refrigerant circuit cutoff valve which is characterized by the above-mentioned.

  According to the present invention, the means for blocking the refrigerant flow with respect to the water heat exchanger is the refrigerant circuit cutoff valve provided at both or one of the inlets and outlets of the refrigerant circuit connected to the water heat exchanger. When the frost is detected on the heat source side heat exchanger, and when it is detected and switched to the defrosting operation by the defrost control means, the refrigerant circuit shut-off valve provided in the refrigerant circuit for the water heat exchanger is closed and the refrigerant flow is reduced. By shutting off, the circulation of the low-pressure refrigerant to the water heat exchanger can be prevented, and the freezing of water in the water heat exchanger and the resulting damage to the water heat exchanger can be prevented. Therefore, with a simple configuration that simply provides a shut-off valve in the refrigerant circuit for the water heat exchanger, the water heat exchanger can be prevented from freezing and breaking, and a plate type heat exchanger that is prone to freezing and breaking can be used. The degree of freedom in selecting the water heat exchanger can be increased.

  Furthermore, in the heat pump system according to the present invention, in the above heat pump system, in the case where the refrigerant circuit cutoff valve is a system in which a dedicated electronic expansion valve is provided in the refrigerant circuit for the second usage unit, the electronic expansion It is characterized by having a configuration shared by a valve.

  According to the present invention, in the case of a system in which the dedicated electronic expansion valve is provided in the refrigerant circuit for the second usage unit, the refrigerant circuit cutoff valve is configured to be shared by the electronic expansion valve. Even without providing a dedicated shut-off valve for shutting off the circuit in the refrigerant circuit, the refrigerant circuit for the water heat exchanger can be shut off during the defrosting operation by utilizing the fully closed function of the electronic expansion valve. Therefore, the installation of the shut-off valve for the refrigerant circuit can be omitted, and the configuration can be simplified and the cost can be reduced.

  Furthermore, in the heat pump system of the present invention, in any one of the heat pump systems described above, the means for blocking the refrigerant flow to the water heat exchanger detects frost formation on the heat source side heat exchanger, At the same time when the four-way switching valve is switched or when the four-way switching valve is switched, the detection value of the low pressure sensor provided in the heat source unit or the pressure sensor provided in the second usage unit has a predetermined value. When it falls below, it is closed and it is set as the structure which interrupts | blocks a refrigerant | coolant flow.

  According to the present invention, the means for blocking the refrigerant flow to the water heat exchanger detects frost formation on the heat source side heat exchanger, and the four-way switching valve is switched at the same time or the four-way switching valve is switched by the signal. When the detection value of the low pressure sensor provided in the heat source unit or the pressure sensor provided in the second usage unit falls below a predetermined value, it is closed and the refrigerant flow is cut off. When the defrosting operation is performed by switching the four-way switching valve, the means (refrigerant circuit shut-off valve) for shutting off the refrigerant flow to the water heat exchanger can be reliably closed, and the refrigerant flow to the water heat exchanger can be shut off. . Therefore, the water heat exchanger can be prevented from freezing / breaking, the control system can be simplified, the occurrence of heat loss on the water circuit side can be eliminated, and energy saving can be achieved.

  According to the present invention, even if the reverse cycle type defrosting control means is adopted, the low-pressure refrigerant does not circulate in the water heat exchanger of the second usage unit during the defrosting operation, and the water is exchanged in the water heat exchanger. The risk of freezing and thereby causing damage to the water heat exchanger can be reliably eliminated, and control such as switching the defrosting operation mode by monitoring the water temperature on the water circuit side during the defrosting operation is made unnecessary. The control system can be simplified. Moreover, generation | occurrence | production of the heat loss by utilizing the heat of the hot water by the side of a water circuit at the time of a defrost operation can be eliminated, and energy saving can be aimed at.

1 is a system diagram of a heat pump system according to an embodiment of the present invention.

Embodiments according to the present invention will be described below with reference to the drawings.
[First Embodiment]
Hereinafter, a first embodiment of the present invention will be described with reference to FIG.
FIG. 1 shows a system diagram of a heat pump system according to the first embodiment of the present invention.
The heat pump system 1 includes a heat source unit 2, a first usage unit 3, and a second usage unit 4, and the first usage unit 3 and the second usage unit 4 are connected in parallel to the heat source unit 2. It is said that.

[Heat source unit]
The heat source unit 2 includes a compressor 5 that compresses the refrigerant, a four-way switching valve 6 that switches the circulation direction of the refrigerant, a heat source side heat exchanger 7 that exchanges heat between the refrigerant and the outside air, and heating that adiabatically expands the refrigerant during the heating cycle. An electronic expansion valve (EEVH) 8, a receiver 9 for storing liquid refrigerant, an electronic expansion valve for cooling (EEVC) 10 that adiabatically expands the refrigerant during the cooling cycle, a liquid component in the refrigerant sucked into the compressor 5 is separated, and gas The liquid side operation valve 12 and the gas side operation valve for connecting the liquid side piping 16 and the gas side piping 17 connected between the accumulator 11, the first usage unit 3 and the second usage unit 4 for sucking only the minute amount 13 or the like (outdoor unit) provided with a heat source side refrigerant circuit 15 connected via a refrigerant pipe 14 as known.

  The heat source unit (outdoor unit) 2 is provided with an outdoor fan 18 that ventilates the outside air to the heat source side heat exchanger 7 and detects the temperature and pressure of the high-pressure refrigerant discharged from the compressor 5. The temperature at each position of the discharge temperature sensor 19 and the high-pressure sensor 20, the suction temperature sensor 21 and the low-pressure sensor 22 for detecting the temperature and pressure of the low-pressure refrigerant sucked into the compressor 5, and the heat source side heat exchanger 7 are detected. Heat exchange temperature sensors 23 and 24 for performing the operation, an outside temperature sensor 25 for detecting the outside air temperature, and the like are provided.

[First use unit]
The first usage unit 3 is an indoor unit that is used for indoor air conditioning (cooling / heating), the liquid side piping 16 and the gas connected to the liquid side operation valve 12 and the gas side operation valve 13 of the heat source unit 2. The use side heat exchanger 28 is connected to the branch liquid pipe 16A and the branch gas pipe 17A branched from the side pipe 17 via refrigerant circuit shut-off valves 26 and 27. The use-side heat exchanger 28 is a direct expansion heat exchanger that heats or cools indoor air by exchanging heat between indoor air ventilated through an indoor fan (not shown) and the refrigerant.

  The first usage unit (indoor unit) 3 includes a suction temperature sensor 29 that detects the temperature of air sucked from the room, a heat exchanger temperature sensor 30 that detects temperatures at both end portions and a central portion of the use-side heat exchanger 27, 31 and 32 are provided.

[Second Usage Unit]
The second usage unit 4 is a hot water indoor unit that generates hot water for hot water supply or heating, and the liquid side pipe 16 and the gas side connected to the liquid side operation valve 12 and the gas side operation valve 13 of the heat source unit 2. A water heat exchanger (refrigerant / water heat exchanger) 35 connected to the branch liquid pipe 16B and the branch gas pipe 17B branched from the pipe 17 via refrigerant circuit shut-off valves 33 and 34 is provided. . The water heat exchanger (refrigerant / water heat exchanger) 35 is a direct expansion heat exchanger that exchanges heat between the refrigerant and water, for example, a plate heat exchanger.

A water circuit 36 composed of a water inlet pipe 36A and a water outlet pipe 36B is connected to the water flow path side of the water heat exchanger (refrigerant / water heat exchanger) 35, and water circulation provided in the water inlet pipe 36A. Water supplied to a tank for storing hot water via the pump 37 or water circulating between the hot water load is circulated.
The second usage unit (hot water indoor unit) 4 is provided with an inlet water temperature sensor 38 and an outlet water temperature sensor 39 for detecting the water temperature of the water inlet and the water outlet to the water heat exchanger 35, and the water heat exchanger. An outlet liquid pipe sensor 40 and a pressure sensor 41 for detecting the outlet temperature and pressure of the refrigerant 35 are provided.

  And with respect to the liquid side operation valve 12 and the gas side operation valve 13 provided at both ends of the heat source side refrigerant circuit 15 of the heat source unit (outdoor unit) 2, the liquid side pipe 16, the gas side pipe 17, and the branch liquid. By connecting the first usage unit (indoor unit) 3 and the second usage unit (warm water indoor unit) 4 in parallel via the pipes 16A and 16B and the branch gas pipes 17A and 17B, one refrigerant circuit (heat pump cycle) ) 42.

  The heat source unit 2 is provided with a heat source side controller 43 that controls the operation of the heat pump system 1. The heat source side controller 43 determines the rotation speed and operation mode of the compressor 5 based on detection values and set values from various sensors provided in the heat source unit 2, the first usage unit 3 and the second usage unit 4. Switching of the four-way switching valve 6 according to the above, the number of rotations of the outdoor fan 18, the opening degree of the heating electronic expansion valve (EEVH) 8 and the cooling electronic expansion valve (EEVC) 10, the refrigerant circuit cutoff valves 26, 27 and 33 , 34, and the number of rotations of the water circulation pump 37 are appropriately controlled, and the operation control means 44 for appropriately controlling the heat pump system 1 according to each operation mode is provided.

  In addition to the operation control means 44 described above, the heat source side controller 43 defrosts the defrost (defrosted) when the heat source system heat exchanger 7 is frosted while operating the heat pump system 1 as a heating cycle. ) Defrosting control means 45 is provided.

  That is, the heat pump system 1 generates hot water for hot water supply or heating by operating only the first usage unit (indoor unit) 3 for cooling / heating operation and operating only the second usage unit (warm water indoor unit) 4. Hot water generation operation, and further, hot water generation / heating operation and the like for simultaneously operating both the first usage unit (indoor unit) 3 and the second usage unit (warm water indoor unit) 4 can be performed. In any case, the operation in the warm water generation operation mode and the warm water generation / heating operation mode is performed by using the heat source side heat exchanger 7 as an evaporator, the use side heat exchanger 27 and a water heat exchanger (refrigerant / water heat exchanger). It becomes the operation | movement by the heating cycle which functions 35 as a condenser (heat radiator).

  In this case, if the outside air temperature is low, frost is generated in the heat source side heat exchanger 7 that functions as an evaporator that absorbs heat from the outside air and evaporates the refrigerant, thereby hindering heat exchange. Therefore, the heat source side heat exchanger 7 When frost is formed, defrosting operation for removing the frost is performed. In the defrosting operation, when the defrosting control means 44 detects that the heat source side heat exchanger 7 has been frosted, the refrigerant circuit 42 is switched from the heating cycle to the cooling cycle by the four-way switching valve 6 and discharged from the compressor 5. The high-temperature and high-pressure refrigerant gas is introduced into the heat source side heat exchanger 7 by the four-way switching valve 6, and a reverse cycle type defrosting method is used in which frost is melted by the heat.

  As described above, the reverse cycle type defrosting method is to defrost the frost by switching the refrigerant circuit 42 from the heating cycle to the cooling cycle and introducing the hot gas refrigerant into the heat source side heat exchanger 7. At this time, the refrigerant used for defrosting in the heat source side heat exchanger 7 is radiated to be condensed and liquefied, decompressed by the cooling electronic expansion valve (EEVC) 10, and then used on the usage side heat of the first usage unit 3. It flows through the exchanger 28 and the water heat exchanger 35 of the second usage unit 4, where it is vaporized and is sucked into the compressor 5 through the four-way switching valve 6. When a low-pressure refrigerant flows through the exchanger 35 to exchange heat with water and evaporate, the water freezes in the water heat exchanger 35 and the water heat exchanger 35 has a risk of breakage.

  Therefore, in the present embodiment, the refrigerant circuit shut-off valves 33 and 34 provided in the refrigerant circuit 42 to the hydrothermal exchanger 35 of the second usage unit 4 with respect to the defrosting control means 45 during the defrosting operation. Is closed to shut off the refrigerant flow to the water heat exchanger 35 and open the refrigerant circuit shut-off valves 26 and 27 to flow the refrigerant only to the use side heat exchanger 28 side of the first use unit 3. It has an added configuration.

  That is, the defrost control means 45 detects the temperature of the heat source side heat exchanger 7 with the heat exchanger temperature sensor 23 during the operation in the heating operation mode, the hot water generation operation mode and the hot water generation / heating operation mode as described above, When it is below a predetermined value, it is determined that the heat source side heat exchanger 7 is frosted, the four-way switching valve 6 is switched to the cooling cycle, and the rotational speed of the compressor 5 is controlled to enter the defrosting operation mode. At the same time, the refrigerant circuit shut-off valves 33 and 34 are closed and the refrigerant circuit shut-off valves 26 and 27 are opened to shut off the refrigerant flow to the water heat exchanger 35 so that only the use-side heat exchanger 28 side of the first use unit 3 is located. A defrosting operation is performed by flowing a refrigerant, and when the detection value of the heat exchange temperature sensor 23 is equal to or higher than a predetermined temperature and the completion of the defrosting is detected, it has a function of returning to the original operation mode.

With the configuration described above, according to the present embodiment, the following operational effects can be obtained.
[Cooling / heating operation using the first usage unit]
In this case, the operation is performed with the refrigerant circuit cutoff valves 26 and 27 open and the refrigerant circuit cutoff valves 33 and 34 closed.
At the time of cooling, the four-way switching valve 6 is switched to the cooling cycle side, and the high-temperature and high-pressure refrigerant discharged from the compressor 5 is guided to the heat source side heat exchanger 7 by the four-way switching valve 6. The refrigerant circuit 42 which returns to the compressor 5 through the electronic expansion valve (EEVC) 10, the use side heat exchanger 28, the four-way switching valve 6, and the accumulator 11 is circulated, the heat source side heat exchanger 7 is a condenser, and the use side heat exchange. By operating the cooler 28 as an evaporator, the air cooled by the use-side heat exchanger 28 is blown into the room and used for cooling.

  During this cooling, the refrigerant circuit shut-off valves 26 and 27 are opened, and the refrigerant is passed through the use side heat exchanger 28 to cool the indoor air and used for indoor cooling, as well as the refrigerant circuit shut-off valves 33 and 34. Of course, it may be used as a system in which cold water is generated by the water heat exchanger 35, the cold water is circulated to the cooling load side, and the cold water cooling is performed.

  On the other hand, at the time of heating, the four-way switching valve 6 is switched to the heating cycle side, and the high-temperature and high-pressure refrigerant discharged from the compressor 5 is guided to the use-side heat exchanger 28 by the four-way switching valve 6. A refrigerant circuit 42 that returns to the compressor 5 through the electronic expansion valve (EEVH) 8, the heat source side heat exchanger 7, the four-way switching valve 6, and the accumulator 11 is circulated, and the use side heat exchanger 28 is a condenser and heat source side heat exchange. By causing the vessel 7 to act as an evaporator, the air heated by the heat radiation in the use side heat exchanger 28 is blown into the room and used for heating.

[Hot water generation operation using the second usage unit]
In this case, the refrigerant circuit cutoff valves 26 and 27 are closed and the refrigerant circuit cutoff valves 33 and 34 are opened, and hot water for hot water supply or heating is generated by the water heat exchanger 35. .
Since this operation is performed in the heating cycle, the four-way switching valve 6 is switched to the heating cycle side.

  For this reason, the high-temperature and high-pressure refrigerant discharged from the compressor 5 is first guided to the water heat exchanger 35 by the four-way switching valve 6, and hereinafter the receiver 9, the heating electronic expansion valve (EEVH) 8, and the heat source side heat exchanger. 7 is circulated in the refrigerant circuit 42 that returns to the compressor 5 through the four-way switching valve 6 and the accumulator 11. At this time, the water heat exchanger 35 functions as a condenser and the heat source side heat exchanger 7 functions as an evaporator, and the water circulating in the water circuit 36 is heated by heat radiation from the water heat exchanger 35 to a predetermined temperature. Of hot water is produced. This hot water is supplied to a hot water storage tank or a hot water load for hot water supply or hot water heating.

[Hot water generation / heating operation using the first usage unit and the second usage unit]
In this case, the refrigerant circuit shut-off valves 26, 27 and 33, 34 are all opened, and the four-way switching valve 6 is operated while being switched to the heating cycle side.
For this reason, the first usage unit and the second usage unit are connected in parallel to the heat source side refrigerant circuit 15 of the heat source unit 2, and accordingly, the high-temperature and high-pressure refrigerant discharged from the compressor 5 is The four-way switching valve 6 leads to both the use side heat exchanger 28 and the water heat exchanger 35 in parallel.

  The refrigerant guided in parallel to the use side heat exchanger 28 and the water heat exchanger 35 is radiated and condensed into liquid, and then merged in the liquid side pipe 16 and introduced into the receiver 9. The refrigerant is circulated in the refrigerant circuit 42 that returns to the compressor 5 through the electronic expansion valve (EEVH) 8, the heat source side heat exchanger 7, the four-way switching valve 6, and the accumulator 11. At this time, indoor air is heated by the use side heat exchanger 28 to be used for heating, and hot water is generated by the water heat exchanger 35 to be used for hot water supply or hot water heating.

[Defrosting operation]
In the heating operation mode using the first usage unit 3 described above, in the hot water generation operation mode using the second usage unit 4, and hot water generation / heating using both the first usage unit 3 and the second usage unit 7 In the operation mode, the refrigerant circuit 42 is operated as a heating cycle. For this reason, depending on the operating conditions, frost formation may occur in the heat source side heat exchanger 7 of the heat source unit 2 exchanging heat with the outside air. This frost formation can be detected by the defrost control means 45 when the heat exchanger temperature sensor 23 provided in the heat source side heat exchanger 7 detects a temperature equal to or lower than a predetermined temperature.

  When the defrost control means 45 detects frost formation on the heat source side heat exchanger 7, the refrigerant circuit 42 is switched to the cooling cycle by the four-way switching valve 6, the compressor 5 is set to the rotation speed for the defrosting operation, and the refrigerant circuit. The shutoff valves 26 and 27 are opened and the refrigerant circuit shutoff valves 33 and 34 are closed to shut off the refrigerant flow to the water heat exchanger 35 so that the refrigerant flows only to the use side heat exchanger 28 side of the first use unit 3. The defrosting operation is started.

  As a result, the high-temperature and high-pressure refrigerant gas discharged from the compressor 5 is led to the heat source side heat exchanger 7 through the four-way switching valve 6, where it is radiated and condensed and liquefied. A refrigerant circuit 42 that returns to the compressor 5 through the electronic expansion valve (EEVC) 10, the use side heat exchanger 28, the four-way switching valve 6, and the accumulator 11 circulates, and frost is thawed by heat dissipation in the heat source side heat exchanger 7. . At this time, since the use side heat exchanger 28 acts as an evaporator, there is a possibility that cold air blows out into the room and disturbs the heating environment. Therefore, the indoor fan of the first use unit 3 is stopped and operated. You can do it.

  In this way, when the frost that has formed on the heat source side heat exchanger 7 is melted and removed, the temperature of the heat source side heat exchanger 7 rises, so that the defrost control means 45 detects the detected value of the heat exchange temperature sensor 23. It is detected that the defrosting is completed when the temperature exceeds the predetermined temperature, the defrosting operation is terminated, and the four-way switching valve 6, the refrigerant circuit shut-off valves 26, 27, 33, 34, etc. are brought into a state before the defrosting operation is started. Return to the original operation mode and resume operation in that mode.

Thus, according to the present embodiment, even if the reverse cycle defrost control means is employed, the low-pressure refrigerant does not circulate in the water heat exchanger 35 of the second usage unit 4 during the defrost operation. The risk of water freezing in the water heat exchanger 35 and the damage of the water heat exchanger 35 can be reliably eliminated, and the water temperature on the water circuit 36 side is monitored during the defrosting operation to remove the defrosting operation mode. It is possible to simplify the control system by eliminating the need for control such as switching.
Moreover, generation | occurrence | production of the heat loss by utilizing the heat of the hot water currently stored by the water circuit 36 side at the time of a defrost operation can be eliminated, and energy saving can be achieved.

  Further, since the means for blocking the refrigerant flow with respect to the water heat exchanger 35 is the refrigerant circuit shut-off valves 33 and 34 provided at the inlet / outlet of the refrigerant circuit 42 connected to the water heat exchanger 34, the heat source When the side heat exchanger 7 is frosted, and when it is detected and switched to the defrosting operation by the defrost control means 45, the refrigerant circuit shut-off valves 33 and 34 provided in the refrigerant circuit 42 to the water heat exchanger 35. By closing the refrigerant flow and blocking the refrigerant flow, the refrigerant flow to the water heat exchanger 35 can be prevented, and water freezing in the water heat exchanger 35 and the resulting damage to the water heat exchanger 35 can be prevented. it can.

  Accordingly, the simple configuration in which the shut-off valves 33 and 34 are provided in the refrigerant circuit 32 for the water heat exchanger 35 can prevent the water heat exchanger 35 from being frozen and damaged, and the plate type that is easily frozen and damaged. The degree of freedom in selecting the water heat exchanger 35 can be increased, for example, a heat exchanger can be used.

  Note that, as described above, the frost formation on the heat source side heat exchanger 7 that exchanges heat with the outside air, and the direct expansion type use side heat exchanger (indoor heat exchanger) 28 that exchanges heat between the refrigerant and the indoor air are used as the evaporator. The reverse cycle defrost control that defrosts by switching to the cooling cycle (= defrost cycle) is a defrost control method that has been established for ordinary air-to-air heat pump air conditioners. In the air heat source heat pump system incorporating the water heat exchanger, development of a new defrosting control method can be omitted.

  In the above embodiment, during the defrosting operation mode, the refrigerant circuit shut-off valves 26 and 27 are opened, the refrigerant circuit shut-off valves 33 and 34 are closed to shut off the refrigerant flow to the water heat exchanger 35, and the refrigerant is used in the first usage unit. The refrigerant circuit shut-off valves 26, 27, 33, 34 provided in the refrigerant circuit 42 are provided exclusively for switching the refrigerant circuit during the defrosting operation. Needless to say, it is also used for switching the refrigerant circuit in other operation modes.

[Other Embodiments]
The present invention is not limited to the invention according to the first embodiment described above, and may be the following embodiment.
(1) In the first embodiment, the defrost control means 45 detects the formation of frost on the heat source side heat exchanger 7 and the end of the defrost based on the detection value of the heat exchanger temperature sensor 23 provided in the heat source side heat exchanger 7. The operation time in the heating cycle is counted regardless of the combination with the detection value of the external temperature sensor 25 that detects the external air temperature or the detection value of the temperature sensor, and is periodically determined every predetermined time. Alternatively, the defrosting operation may be performed.

  (2) In the first embodiment, the refrigerant circuit shut-off valves 33 and 34 are provided at both the inlet and outlet of the refrigerant circuit (branch liquid pipe 16B and branch gas pipe 17B) 42 connected to the water heat exchanger 35. However, in order to prevent the circulation of the refrigerant during the defrosting operation, only one of the refrigerant circuit shut-off valves 33 and 34 may be provided. In this case, the number of installed refrigerant circuit shut-off valves is reduced. Thus, the cost can be reduced.

  (3) In the first embodiment, the heating electronic expansion valve (EEVH) 8 and the cooling electronic expansion valve (EEVC) 10 are provided on the heat source unit (outdoor unit) 2 side. The electronic expansion valve (EEVC) 10 may be separately distributed in the branch liquid pipes 16A and 16B of the first usage unit (indoor unit) 3 and the second usage unit (hot water indoor unit) 4, respectively.

  In this case, the electronic expansion valve (EEVC) 10 that is arranged in a distributed manner is used to fully shut off the refrigerant flow to the water heat exchanger 35 during the defrosting operation of the electronic expansion valve (EEVC) 10. The refrigerant circuit shut-off valve (shut-off valve 33) can also be used, thereby reducing the number of installed refrigerant circuit shut-off valves, thereby simplifying the configuration of the refrigerant circuit 42 and reducing the cost. Can do.

  (4) Furthermore, in the said 1st Embodiment, the presence or absence of frost formation is determined by the defrost control means 45 based on the detected value of the heat exchanger temperature sensor 23 provided in the heat source side heat exchanger 7 (detection). The four-way switching valve 6 is switched to the cooling cycle according to the signal, and the refrigerant circuit cutoff valves 33 and 34 are closed. However, the closing of the refrigerant circuit cutoff valves 33 and 34 detects frost formation. When the four-way switching valve 6 is switched for defrosting, the low-pressure pressure drops rapidly, so that the low-pressure sensor 22 or the pressure sensor 41 detects that the pressure has fallen below a predetermined value, and the refrigerant circuit The shut-off valves 33 and 34 may be closed.

  The present invention is not limited to the invention according to the above-described embodiment, and can be appropriately modified without departing from the gist thereof. For example, in the above-described embodiment, an example in which one first usage unit (indoor unit) 3 is connected has been described. However, a multi-type heat pump system in which a plurality of first usage units (indoor units) 3 are connected in parallel may be used. Good.

DESCRIPTION OF SYMBOLS 1 Heat pump system 2 Heat source unit 3 1st utilization unit 4 2nd utilization unit 5 Compressor 6 Four-way switching valve 7 Heat source side heat exchanger 28 Utilization side heat exchanger 33,34 Refrigerant circuit shielding valve (Refrigerant flow with respect to water heat exchanger) Means to block
35 Water heat exchanger 42 Refrigerant circuit 45 Defrost control means

Claims (4)

A heat source unit having a compressor, a four-way switching valve, and a heat source side heat exchanger for exchanging heat between the refrigerant and the outside air;
A first usage unit having a usage-side heat exchanger for exchanging heat between the refrigerant and room air;
A second usage unit having a water heat exchanger for exchanging heat between the refrigerant and water and generating hot water for hot water supply or heating;
A one-system refrigerant circuit configured by connecting the first usage unit and the second usage unit in parallel to the heat source unit;
Defrosting control means for defrosting the refrigerant circuit by switching from a heating cycle to a cooling cycle by the four-way switching valve when frosted on the heat source side heat exchanger;
The defrosting control unit is configured to block a refrigerant flow with respect to the water heat exchanger of the second usage unit and flow the refrigerant only to the usage side heat exchanger side of the first usage unit during the defrosting operation. A heat pump system characterized by comprising.   The means for shutting off the refrigerant flow to the water heat exchanger is a refrigerant circuit shut-off valve provided at both or one of the inlets and outlets of the refrigerant circuit connected to the water heat exchanger. The heat pump system according to claim 1.   In the case of a system in which a dedicated electronic expansion valve is provided in the refrigerant circuit for the second usage unit, the refrigerant circuit cutoff valve is configured to be shared by the electronic expansion valve. The heat pump system according to claim 2. The means for blocking the refrigerant flow to the water heat exchanger detects frost formation on the heat source side heat exchanger, and at the same time the four-way switching valve is switched by the signal, or the four-way switching valve is switched, When the detection value of the low pressure sensor provided in the heat source unit or the pressure sensor provided in the second usage unit falls below a predetermined value, the refrigerant flow is closed and the refrigerant flow is shut off. The heat pump system according to any one of claims 1 to 3, wherein

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