WO2013008365A1

WO2013008365A1 - Air-conditioning device

Info

Publication number: WO2013008365A1
Application number: PCT/JP2012/001980
Authority: WO
Inventors: 傑鳩村; 山下　浩司; 裕之森本
Original assignee: 三菱電機株式会社
Priority date: 2011-07-14
Filing date: 2012-03-22
Publication date: 2013-01-17
Also published as: WO2013008278A1; US20140182320A1; CN103620325A; EP2733444A1; EP2733444A4; US9494361B2; ES2904812T3; EP2733444B1; CN103620325B

Abstract

An air-conditioning device (100) provided with the following: an outdoor unit (1) containing a compressor (10), a first refrigerant-path switching device (11), and a heat-source-side heat exchanger (12); a heat-medium exchanger (3) containing an inter-heat-medium heat exchanger (15), a flow-restriction device (16), a second refrigerant-path switching device (18), and a pump (21); and at least one indoor unit (2) containing a usage-side heat exchanger (26). The compressor (10), the first refrigerant-path switching device (11), the flow-restriction device (16), the second refrigerant-path switching device (18), and the inter-heat-medium heat exchanger (15) are connected by refrigerant piping, forming a refrigeration-cycle circuit. The inter-heat-medium heat exchanger (15) and the usage-side heat exchanger (26) are connected by heat-medium piping, forming a heat-medium circulation circuit through which a heat medium other than the refrigerant circulates. By switching the first refrigerant-path switching device (11), this air-conditioning device enters a defrost mode wherein the refrigerant discharged from the compressor (10) is supplied to the heat-source-side heat exchanger (12). In said defrost mode, some of the refrigerant flowing from the heat-source-side heat exchanger (12) is supplied to the inter-heat-medium heat exchanger (15) without going through the flow-restriction device (16), and the rest is returned to the outdoor unit (1) without going through either the flow-restriction device (16) or the inter-heat-medium heat exchanger (15).

Description

Air conditioner

The present invention relates to an air conditioner applied to, for example, a building multi air conditioner.

Some air conditioners include a heat source unit (outdoor unit) arranged outside a building and an indoor unit arranged inside a building, such as a building multi-air conditioner. The refrigerant circulating in the refrigerant circuit of such an air conditioner radiates heat (heat absorption) to the air supplied to the heat exchanger of the indoor unit, and heats or cools the air. The heated or cooled air is sent into the air-conditioning target space for heating or cooling.
In such an air conditioner, a building normally has a plurality of indoor spaces, and accordingly, the indoor unit also includes a plurality of indoor units. Moreover, when the scale of the building is large, the refrigerant pipe connecting the outdoor unit and the indoor unit may be 100 m. When the length of the pipe connecting the outdoor unit and the indoor unit is long, the amount of refrigerant charged in the refrigerant circuit increases accordingly.

Such indoor units of multi-air conditioners for buildings are usually arranged and used in indoor spaces where people are present (for example, office spaces, living rooms, stores, etc.). If for some reason the refrigerant leaks from the indoor unit placed in the indoor space, depending on the type of refrigerant, it may be flammable or toxic, which may be a problem from the perspective of human impact and safety There is. Moreover, even if it is a refrigerant | coolant which is not harmful to a human body, the oxygen concentration in indoor space falls by a refrigerant | coolant leak, and it is assumed that it influences a human body.
In order to cope with such problems, a secondary loop method is adopted, a refrigerant is circulated in the primary loop, and a heat medium such as water and brine is circulated in the secondary loop, There is a method of transferring the heat or cold of the refrigerant to the heat medium (see, for example, Patent Document 1). The technology described in Patent Document 1 transmits the heat and cold generated in the primary loop to the secondary loop via a heat exchanger between heat media such as a plate heat exchanger and a double pipe. Heat and cold are supplied to the indoor unit by the secondary loop. Further, the technology described in Patent Document 1 suppresses the influence on the human body due to refrigerant leakage because the piping corresponding to the secondary loop through which the non-hazardous heat medium circulates is disposed in the vicinity of the space where the person is present. Is something that can be done.

On the other hand, when performing the heating operation and the outdoor unit heat exchanger functions as an evaporator, the fins of the outdoor unit heat exchanger where the outdoor is low outside air are likely to be frosted. Due to this frost formation, heat exchange between the outdoor air supplied by the fan and the refrigerant flowing through the tubes of the outdoor unit heat exchanger is hindered, and the heat exchange efficiency is reduced. Therefore, a technique for performing a defrost operation for supplying a high-temperature refrigerant to the outdoor unit heat exchanger in order to remove frost from the outdoor unit heat exchanger is known.

When this defrost operation is adopted in the technique described in Patent Document 1, the refrigerant flowing into the heat exchanger related to heat medium through the outdoor unit heat exchanger and the expansion device is compressed again. Inhaled into the machine. Here, the refrigerant that has flowed out of the expansion device has a low temperature due to the action of the condenser of the outdoor heat exchanger, and is depressurized by the action of the expansion device.
As a result, the refrigerant that has flowed out of the expansion device absorbs heat from the heat medium in the secondary side loop, evaporates in the heat exchanger related to heat medium, and may freeze the heat medium. Then, the air conditioning apparatus provided with the bypass piping which bypasses the heat exchanger between heat media is proposed (for example, refer patent document 2). The technique described in Patent Document 2 is configured such that the flow resistance of the bypass pipe is smaller than that of the heat exchanger related to heat medium, the amount of refrigerant flowing into the heat exchanger related to heat medium is reduced, and the heat medium of the secondary loop It is intended to suppress freezing.

WO 10/049998 (for example, see page 3 and FIG. 1) Japanese Patent Laying-Open No. 2005-274134 (for example, see page 2 and FIG. 3)

The technique described in Patent Document 1 does not describe the suppression of freezing of the heat medium during the defrost operation. If the technique described in Patent Document 2 is adopted in the technique described in Patent Document 1, and the defrost operation is performed, the amount of low-temperature / low-pressure refrigerant flowing out of the expansion device flows into the heat exchanger between the heat mediums. Suppression is possible. However, even in this case, the low-temperature / low-pressure refrigerant flows into the heat exchanger between the heat mediums, and the countermeasure for suppressing freezing of the heat medium in the secondary loop is not sufficient. And if the heat medium of the secondary side loop freezes, circulation of the heat medium to the indoor unit is hindered, and air conditioning efficiency may be reduced. Further, since the circulation of the heat medium is hindered, there is a possibility that the pressure of the heat medium pipe may be increased and the pipe may be broken. Therefore, it has been desired to further enhance safety considerations.
That is, when the technique described in Patent Document 2 is adopted in the technique of Patent Document 1 and the defrost operation is performed, the operation reliability of the air conditioner may be reduced.

An object of the air conditioning apparatus according to the present invention is to provide an air conditioning apparatus that suppresses freezing of a heat medium, an antifreeze liquid, and the like and improves operational reliability during defrost operation.

The air conditioner according to the present invention includes an outdoor unit on which a compressor, a first refrigerant flow switching device, and a heat source side heat exchanger are mounted, a heat exchanger between heat media, a throttling device, and a second refrigerant flow switching. Apparatus, a heat medium converter mounted with a pump, and at least one indoor unit mounted with a use-side heat exchanger, the compressor, the first refrigerant flow switching device, the expansion device, A refrigeration cycle circuit is configured by connecting the second refrigerant flow switching device and the heat exchanger between heat medium with a refrigerant pipe, and the heat exchanger between heat medium and the use side heat exchanger are connected with a heat medium pipe. A defrost operation in which a heat medium circulation circuit in which a heat medium different from the refrigerant circulates is configured, the first refrigerant flow switching device is switched, and the refrigerant discharged from the compressor is supplied to the heat source side heat exchanger. In the air conditioner for executing the mode, the differential In the strike operation mode, a part of the refrigerant flowing out from the heat source side heat exchanger is supplied to the heat exchanger related to heat medium without going through the expansion device, and the rest is the expansion device and the heat. It returns to the outdoor unit without going through the inter-medium heat exchanger.

The air conditioner according to the present invention supplies the refrigerant flowing from the outdoor unit to the heat medium converter in the defrost operation mode from the side not connected to the expansion device to the heat exchanger related to heat medium. By doing in this way, since the evaporation of the refrigerant | coolant which flowed into the heat exchanger between heat media is suppressed, the air conditioning apparatus which concerns on this invention can suppress freezing of a heat medium, an antifreeze liquid, etc. Thereby, the air conditioning apparatus which concerns on this invention can improve the operation | movement reliability of an air conditioning apparatus.

It is the schematic which shows the example of installation of the air conditioning apparatus which concerns on embodiment of this invention. It is a refrigerant circuit structural example of the air conditioning apparatus which concerns on embodiment of this invention. It is a refrigerant circuit figure which shows the flow of the refrigerant | coolant at the time of the cooling only operation mode of the air conditioning apparatus shown in FIG. It is a refrigerant circuit figure which shows the flow of the refrigerant | coolant at the time of the heating only operation mode of the air conditioning apparatus shown in FIG. It is a refrigerant circuit diagram which shows the flow of the refrigerant | coolant at the time of the cooling main operation mode of the air conditioning apparatus shown in FIG. It is a refrigerant circuit figure which shows the flow of the refrigerant | coolant at the time of heating main operation mode of the air conditioning apparatus shown in FIG. It is a refrigerant circuit diagram which shows the flow of the refrigerant | coolant at the time of the defrost operation mode of the air conditioning apparatus shown in FIG. It is a refrigerant circuit diagram which shows the flow of the refrigerant | coolant in the defrost operation mode 2-1 which is one form among the defrost operation modes 2 which consists of five forms. FIG. 6 is a refrigerant circuit diagram illustrating a refrigerant flow in a defrost operation mode 2-5, which is one form of the defrost operation mode 2.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
The air conditioner according to the present embodiment is an improvement that reduces the amount of low-temperature refrigerant so that it flows into a heat exchanger (heat exchanger 15 between heat medium) that exchanges heat between the refrigerant and the heat medium during defrost operation. Has been made. First, an installation example of an air conditioner will be described with reference to FIG.
FIG. 1 is a schematic diagram illustrating an installation example of an air conditioner according to an embodiment of the present invention. This air conditioner has a refrigerant circulation circuit A that circulates a refrigerant (heat source side refrigerant) and a heat medium circulation circuit B that circulates a heat medium, and the indoor unit 2 is operated in a cooling mode or a heating mode. Can be freely selected.

The air conditioner employs a method of indirectly using a refrigerant (indirect method). That is, the cold or warm heat stored in the heat source side refrigerant is transmitted to a refrigerant (hereinafter referred to as a heat medium) different from the heat source side refrigerant, and the air-conditioning target space is cooled or heated with the cold heat or heat stored in the heat medium.

As shown in FIG. 1, the air-conditioning apparatus according to the present embodiment includes a single outdoor unit 1 that is a heat source unit, a plurality of indoor units 2, and an outdoor unit 1 and an indoor unit 2. And a heat medium relay unit 3 interposed therebetween. The heat medium relay unit 3 performs heat exchange between the heat source side refrigerant and the heat medium. The outdoor unit 1 and the heat medium relay unit 3 are connected by a refrigerant pipe 4 for circulating the heat source side refrigerant. The heat medium relay unit 3 and the indoor unit 2 are connected by a pipe (heat medium pipe) 5 for circulating the heat medium. The cold or warm heat generated by the outdoor unit 1 is delivered to the indoor unit 2 via the heat medium converter 3.

The outdoor unit 1 is usually disposed in an outdoor space 6 that is a space (for example, a rooftop) outside a building 9 such as a building, and supplies cold or hot energy to the indoor unit 2 via the heat medium converter 3. It is.
The indoor unit 2 is disposed at a position where cooling air or heating air can be supplied to the indoor space 7 which is a space (for example, a living room) inside the building 9, and is used for cooling the indoor space 7 serving as a space to be air-conditioned. Air or heating air is supplied.
The heat medium relay unit 3 is installed at a position different from the outdoor space 6 and the indoor space 7 as a separate housing from the outdoor unit 1 and the indoor unit 2. The heat medium converter 3 is connected to the outdoor unit 1 and the indoor unit 2 via the refrigerant pipe 4 and the pipe 5, respectively, and transmits cold heat or hot heat supplied from the outdoor unit 1 to the indoor unit 2. is there.

As shown in FIG. 1, in the air conditioner according to the present embodiment, the outdoor unit 1 and the heat medium converter 3 are connected via two refrigerant pipes 4, and the heat medium converter 3 and Each indoor unit 2a to 2d is connected via two pipes 5. Thus, in the air conditioning apparatus according to the embodiment, construction is easy by connecting each unit (the outdoor unit 1, the indoor unit 2, and the heat medium relay unit 3) via the refrigerant pipe 4 and the pipe 5. It has become.

In FIG. 1, the heat medium converter 3 is inside the building 9 but is a space other than the indoor space 7 such as a ceiling (for example, a space such as a ceiling behind the building 9, hereinafter, It is illustrated by way of example as being installed in a space 8). The heat medium relay 3 may be installed in a common space where there is an elevator or the like. Moreover, in FIG. 1, although the case where the indoor unit 2 is a ceiling cassette type is shown as an example, it is not limited to this. That is, the air conditioner according to the present embodiment is a ceiling-embedded type, ceiling-suspended type, as long as heating air or cooling air can be blown directly into the indoor space 7 by a duct or the like, It can be of any kind.

Further, in FIG. 1, the case where the outdoor unit 1 is installed in the outdoor space 6 is shown as an example, but the present invention is not limited to this. For example, the outdoor unit 1 may be installed in an enclosed space such as a machine room with a ventilation port, or the interior of the building 9 if the exhaust heat can be exhausted outside the building 9 by an exhaust duct. You may install in. Even when the water-cooled outdoor unit 1 is used, it may be installed inside the building 9. Even if the outdoor unit 1 is installed in such a place, no particular problem occurs.

The heat medium converter 3 can also be installed in the vicinity of the outdoor unit 1. However, it should be noted that if the distance from the heat medium relay unit 3 to the indoor unit 2 is too long, the power for transporting the heat medium becomes considerably large, and the energy saving effect is diminished. Furthermore, the number of connected outdoor units 1, indoor units 2, and heat medium converters 3 is not limited to the number illustrated in FIG. 1. For example, the building 9 in which the air conditioner according to the present embodiment is installed. The number of units may be determined according to.

FIG. 2 is a refrigerant circuit configuration example of the air-conditioning apparatus (hereinafter referred to as air-conditioning apparatus 100) according to the embodiment of the present invention. Based on FIG. 2, the detailed structure of the air conditioning apparatus 100 is demonstrated. As illustrated in FIG. 2, the outdoor unit 1 and the heat medium relay unit 3 are connected to each other through a heat exchanger related to heat medium 15 a and a heat exchanger related to heat medium 15 b provided in the heat medium converter 3. Connected by piping 4. Moreover, the heat medium relay unit 3 and the indoor unit 2 are also connected by the pipe 5 via the heat exchanger related to heat medium 15a and the heat exchanger related to heat medium 15b. The refrigerant pipe 4 will be described in detail later.

[Outdoor unit 1]
The outdoor unit 1 stores a compressor 10 that compresses refrigerant, a first refrigerant flow switching device 11 that includes a four-way valve, a heat source side heat exchanger 12 that functions as an evaporator or a condenser, and excess refrigerant. An accumulator 19 is connected to and mounted on the refrigerant pipe 4.
The outdoor unit 1 is also provided with a first connection pipe 4a, a second connection pipe 4b, a check valve 13a, a check valve 13b, a check valve 13c, and a check valve 13d. Regardless of the operation that the indoor unit 2 requires, the heat medium is provided by providing the first connection pipe 4a, the second connection pipe 4b, the check valve 13a, the check valve 13b, the check valve 13c, and the check valve 13d. The flow of the heat source side refrigerant flowing into the converter 3 can be in a certain direction. That is, the refrigerant flowing out of the outdoor unit 1 flows out of the outdoor unit 1 through the refrigerant pipe 4 (first refrigerant pipe) connected to the

check valves

13a and 13b, and then from the heat medium converter 3 to the outdoor unit. 1 flows into the outdoor unit 1 through the refrigerant pipe 4 (second refrigerant pipe) connected to the

check valves

13c and 13d.
Further, the outdoor unit 1 includes a first outdoor temperature sensor 40a that detects the temperature of the refrigerant flowing into the heat source side heat exchanger 12 during the defrost operation for removing frost generated in the heat source side heat exchanger 12, and the heat source side. A second outdoor temperature sensor 40b that detects the temperature of the refrigerant flowing out of the heat exchanger 12 is provided.

The compressor 10 sucks the heat source side refrigerant and compresses the heat source side refrigerant to a high temperature and high pressure state. For example, the compressor 10 may be composed of an inverter compressor capable of capacity control.
The first refrigerant flow switching device 11 has a flow of the heat source side refrigerant in the heating operation mode (in the heating only operation mode and the heating main operation mode) and in the cooling operation mode (in the all cooling operation mode and the cooling main operation mode). ) To switch the flow of the heat source side refrigerant.

The heat source side heat exchanger 12 functions as an evaporator during heating operation, functions as a radiator (gas cooler) during cooling operation, and between the air supplied from a blower such as a fan (not shown) and the heat source side refrigerant. Heat exchange is performed.
The accumulator 19 is provided on the suction side of the compressor 10, and surplus refrigerant due to a difference between the heating operation mode and the cooling operation mode, a change in the transient operation (for example, a change in the number of indoor units 2 operated). And excess refrigerant generated by load conditions.

The first outdoor temperature sensor 40a detects the temperature of the refrigerant flowing into the heat source side heat exchanger 12 (inlet side temperature). The first outdoor temperature sensor 40 a may be provided in the refrigerant pipe 4 on the inlet side of the heat source side heat exchanger 12.
The second outdoor temperature sensor 40b detects the temperature of the refrigerant (outlet side temperature) that has flowed out of the heat source side heat exchanger 12. The second outdoor temperature sensor 40 b may be provided in the refrigerant pipe 4 on the outlet side of the heat source side heat exchanger 12.

The first outdoor temperature sensor 40 a and the second outdoor temperature sensor 40 b are connected to a control device 70 that performs overall control of the operation of the air conditioner 100. And the detection result of the 1st outdoor temperature sensor 40a and the 2nd outdoor temperature sensor 40b is transmitted to the control apparatus 70, and the control apparatus 70 judges whether the implementation of the defrosting operation of the heat source side heat exchanger 12 is performed. . In addition, the 1st outdoor temperature sensor 40a and the 2nd outdoor temperature sensor 40b are good to comprise, for example with a thermistor etc.

[Indoor unit 2]
A use side heat exchanger 26 is mounted on the indoor unit 2. The use side heat exchanger 26 is connected to the heat medium flow control device 25 and the second heat medium flow switching device 23 of the heat medium converter 3 by the pipe 5. The use-side heat exchanger 26 performs heat exchange between air supplied from a blower such as a fan (not shown) and a heat medium, and generates heating air or cooling air to be supplied to the indoor space 7. To do.

In FIG. 2, an example is shown in which four indoor units 2 are connected to the heat medium relay unit 3, and as an indoor unit 2a, an indoor unit 2b, an indoor unit 2c, and an indoor unit 2d from the lower side of the page, It is shown. In accordance with the indoor unit 2a to the indoor unit 2d, the use side heat exchanger 26 also uses the use side heat exchanger 26a, the use side heat exchanger 26b, the use side heat exchanger 26c, and the use side heat exchange from the lower side of the drawing. It is shown as a container 26d. The number of connected indoor units 2 is not limited to four as shown in FIG.

[Heat medium converter 3]
The heat medium converter 3 includes two heat medium heat exchangers 15 (15a, 15b) that exchange heat between the refrigerant and the heat medium, two expansion devices 16 (16a, 16b) that depressurize the refrigerant, and a refrigerant pipe 4. Two opening / closing devices 17 (17a, 17b) for opening and closing the flow path, two second refrigerant flow switching devices 18 (18a, 18b) for switching the refrigerant flow path, and two pumps 21 (21a, 21b), four first heat medium flow switching devices 22 (22a to 22d) connected to one of the pipes 5, and four second heat medium flow switching devices 23 (23a to 22d) connected to the other of the pipes 5 23d) and four heat medium flow control devices 25 (25a to 25d) connected to the pipe 5 to which the second heat medium flow switching device 22 is connected.

The two

heat exchangers

15a, 15b function as condensers (radiators) or evaporators, perform heat exchange between the heat source side refrigerant and the heat medium, and are generated by the outdoor unit 1 and stored in the heat source side refrigerant. The generated cold or warm heat is transmitted to the heat medium. The heat exchanger related to heat medium 15a is provided between the expansion device 16a and the second refrigerant flow switching device 18a in the refrigerant circuit A and serves to cool the heat medium in the cooling / heating mixed operation mode. is there. The heat exchanger related to heat medium 15b is provided between the expansion device 16b and the second refrigerant flow switching device 18b in the refrigerant circuit A and serves to heat the heat medium in the cooling / heating mixed operation mode. is there.

The two

expansion devices

16a and 16b function as a pressure reducing valve and an expansion valve, and expand the heat source side refrigerant by reducing the pressure. The expansion device 16a is provided on the upstream side of the heat exchanger related to heat medium 15a in the flow of the heat source side refrigerant in the cooling only operation mode. The expansion device 16b is provided on the upstream side of the heat exchanger related to heat medium 15b in the flow of the heat source side refrigerant in the cooling only operation mode. The two expansion devices 16 may be configured by a device whose opening degree can be variably controlled, for example, an electronic expansion valve.

The two opening / closing devices 17a and 17b are configured by a two-way valve or the like and open / close the refrigerant pipe 4. That is, the opening / closing of the two opening / closing devices 17a and 17b is controlled according to an operation mode to be described later in order to adjust the flow of the refrigerant supplied from the refrigerant piping 4 (first refrigerant piping).

The two second refrigerant flow switching devices 18a and 18b are configured by four-way valves or the like, and switch the flow of the heat source side refrigerant according to the operation mode. The second refrigerant flow switching device 18a is provided on the downstream side of the heat exchanger related to heat medium 15a in the flow of the heat source side refrigerant in the cooling only operation mode. The second refrigerant flow switching device 18b is provided on the downstream side of the heat exchanger related to heat medium 15b in the flow of the heat source side refrigerant in the cooling only operation mode.
Note that the second refrigerant flow switching device 18 may not be a four-way valve, and may be configured by combining, for example, a three-way valve, a two-way valve, and an electromagnetic valve.

The two pumps 21 a and 21 b circulate the heat medium in the pipe 5. The pump 21 a is provided in the pipe 5 between the heat exchanger related to heat medium 15 a and the second heat medium flow switching device 23. The pump 21 b is provided in the pipe 5 between the heat exchanger related to heat medium 15 b and the second heat medium flow switching device 23. These pumps 21 may be constituted by, for example, pumps capable of capacity control. The pump 21a may be provided in the pipe 5 between the heat exchanger related to heat medium 15a and the first heat medium flow switching device 22. Further, the pump 21b may be provided in the pipe 5 between the heat exchanger related to heat medium 15b and the first heat medium flow switching device 22.

The four first heat medium flow switching devices 22a to 22d are configured by three-way valves or the like, and switch the heat medium flow paths. The first heat medium flow switching device 22 is provided in a number (here, four) according to the number of indoor units 2 installed. In the first heat medium flow switching device 22, one of the three sides is in the heat exchanger 15a, one of the three is in the heat exchanger 15b, and one of the three is in the heat medium flow rate. Each is connected to the adjusting device 25 and provided on the outlet side of the heat medium flow path of the use side heat exchanger 26. In correspondence with the indoor unit 2, the first heat medium flow switching device 22a, the first heat medium flow switching device 22b, the first heat medium flow switching device 22c, and the first heat medium flow from the lower side of the drawing. This is illustrated as a switching device 22d.

The four second heat medium flow switching devices 23a to 23d are constituted by three-way valves or the like, and switch the heat medium flow paths. The number of the second heat medium flow switching devices 23 is set according to the number of installed indoor units 2 (here, four). In the second heat medium flow switching device 23, one of the three heat transfer medium heat exchangers 15a, one of the three heat transfer medium heat exchangers 15b, and one of the three heat transfer side heats. The heat exchanger is connected to the exchanger 26 and provided on the inlet side of the heat medium flow path of the use side heat exchanger 26. In correspondence with the indoor unit 2, the second heat medium flow switching device 23a, the second heat medium flow switching device 23b, the second heat medium flow switching device 23c, and the second heat medium flow from the lower side of the drawing. This is illustrated as a switching device 23d.

The four heat medium flow control devices 25a to 25d are configured by two-way valves or the like that can control the opening area, and adjust the flow rate of the heat medium flowing through the pipe 5. The number of the heat medium flow control devices 25 is set according to the number of indoor units 2 installed (four in this case). One of the heat medium flow control devices 25 is connected to the use side heat exchanger 26 and the other is connected to the first heat medium flow switching device 22, and is connected to the outlet side of the heat medium flow channel of the use side heat exchanger 26. Is provided. In correspondence with the indoor unit 2, the heat medium flow adjustment device 25 a, the heat medium flow adjustment device 25 b, the heat medium flow adjustment device 25 c, and the heat medium flow adjustment device 25 d are illustrated from the lower side of the drawing. Further, the heat medium flow control device 25 may be provided on the inlet side of the heat medium flow path of the use side heat exchanger 26.

Further, the heat medium relay 3 includes various detection means (two first temperature sensors 31 (31a, 31b), four second temperature sensors 34 (34a to 34d), and four third temperature sensors 35 (35a to 35a). 35d) Two pressure sensors 36 (36a, 36b)) are provided. Information (for example, temperature information, pressure information, and heat source side refrigerant concentration information) detected by these detection means is sent to a control device 70 that performs overall control of the operation of the air conditioner 100, and the drive frequency of the compressor 10. The rotation speed of a blower (not shown) provided near the heat source side heat exchanger 12 and the use side heat exchanger 26, switching of the first refrigerant flow switching device 11, driving frequency of the pump 21, second refrigerant flow switching device 18, switching of the first heat medium flow switching device 22, switching of the second heat medium flow switching device, and the like.

The two

first temperature sensors

31a and 31b detect the temperature of the heat medium flowing out from the intermediate heat exchanger 15, that is, the temperature of the heat medium at the outlet of the intermediate heat exchanger 15, for example, a thermistor or the like. It is good to comprise. The first temperature sensor 31a is provided in the pipe 5 on the inlet side of the pump 21a. The first temperature sensor 31b is provided in the pipe 5 on the inlet side of the pump 21b.

The four second temperature sensors 34a to 34d are provided between the first heat medium flow switching device 22 and the heat medium flow control device 25, and detect the temperature of the heat medium flowing out from the use side heat exchanger 26. It is good that it is composed of a thermistor or the like. The number of the second temperature sensors 34 (four here) according to the number of indoor units 2 installed is provided. In correspondence with the indoor unit 2, the second temperature sensor 34a, the second temperature sensor 34b, the second temperature sensor 34c, and the second temperature sensor 34d are illustrated from the lower side of the drawing.

The four third temperature sensors 35a to 35d are provided on the inlet side or the outlet side of the heat source side refrigerant of the heat exchanger related to heat medium 15, and the temperature or heat medium of the heat source side refrigerant flowing into the heat exchanger related to heat medium 15 The temperature of the heat source side refrigerant that has flowed out of the intermediate heat exchanger 15 is detected, and it may be constituted by a thermistor or the like. The third temperature sensor 35a is provided between the heat exchanger related to heat medium 15a and the second refrigerant flow switching device 18a. The third temperature sensor 35b is provided between the heat exchanger related to heat medium 15a and the expansion device 16a. The third temperature sensor 35c is provided between the heat exchanger related to heat medium 15b and the second refrigerant flow switching device 18b. The third temperature sensor 35d is provided between the heat exchanger related to heat medium 15b and the expansion device 16b.

The two pressure sensors 36a and 36b are for detecting the pressure of the refrigerant. The pressure sensor 36a detects the pressure of the heat source side refrigerant flowing between the heat exchanger related to heat medium 15a and the second refrigerant flow switching device 18a, similarly to the installation position of the third temperature sensor 35a. Similarly to the installation position of the third temperature sensor 35d, the pressure sensor 36b is provided between the heat exchanger related to heat medium 15b and the expansion device 16b, and between the heat exchanger related to heat medium 15b and the expansion device 16b. The pressure of the heat source side refrigerant flowing between them is detected.

The control device 70 is configured by a microcomputer or the like, and based on detection information from various detection means and instructions from the remote controller, the driving frequency of the compressor 10, the rotational speed of the blower (including ON / OFF), the first refrigerant Switching of the flow switching device 11, driving of the pump 21, opening of the expansion device 16, opening / closing of the switching device 17, switching of the second refrigerant flow switching device 18, switching of the first heat medium flow switching device 22, (2) The switching of the heat medium flow switching device 23 and the opening degree of the heat medium flow control device 25 are controlled. That is, the control device 70 performs overall control of various devices and executes a defrost operation and each operation mode to be described later. In FIG. 2, an example in which the control device 70 is provided in the heat medium relay unit 3 is illustrated, but the present invention is not limited thereto. That is, the control device 70 may be provided for each unit of the indoor unit 2 or may be provided in the heat medium relay unit 3. Moreover, you may comprise the some control apparatus 70 in the outdoor unit 1, the indoor unit 2, and the heat medium converter 3, so that cooperation control can be performed by communication.

The piping 5 for circulating the heat medium is composed of one connected to the heat exchanger related to heat medium 15a and one connected to the heat exchanger related to heat medium 15b. The pipe 5 is branched (here, four branches each) according to the number of indoor units 2 connected to the heat medium relay unit 3. The pipe 5 is connected by a first heat medium flow switching device 22 and a second heat medium flow switching device 23. By controlling the first heat medium flow switching device 22 and the second heat medium flow switching device 23, the heat medium from the heat exchanger related to heat medium 15a flows into the use-side heat exchanger 26, or the heat medium Whether the heat medium from the intermediate heat exchanger 15b flows into the use side heat exchanger 26 is determined.

In the air conditioner 100, the refrigerant of the compressor 10, the first refrigerant flow switching device 11, the heat source side heat exchanger 12, the switchgear 17, the second refrigerant flow switching device 18, and the heat exchanger related to heat medium 15 is used. The flow path, the expansion device 16 and the accumulator 19 are connected by the refrigerant pipe 4 to constitute the refrigerant circulation circuit A. Further, the heat medium flow path of the intermediate heat exchanger 15, the pump 21, the first heat medium flow switching device 22, the heat medium flow control device 25, the use side heat exchanger 26, and the second heat medium flow path The switching device 23 is connected by a pipe 5 to constitute a heat medium circulation circuit B. That is, a plurality of usage-side heat exchangers 26 are connected in parallel to each of the heat exchangers between heat media 15, and the heat medium circulation circuit B has a plurality of systems.

Therefore, in the air conditioning apparatus 100, the outdoor unit 1 and the heat medium converter 3 are connected via the heat exchanger related to heat medium 15 provided in the heat medium converter 3, so that the heat medium converter 3 and the indoor unit The machine 2 is also connected through a heat exchanger 15 between heat media. That is, in the air conditioner 100, the heat source side refrigerant circulating in the refrigerant circuit A and the heat medium circulating in the heat medium circuit B exchange heat in the intermediate heat exchanger 15a and the intermediate heat exchanger 15b. It is supposed to be.

[Description of operation mode]
Next, each operation mode executed by the air conditioner 100 will be described. The air conditioner 100 can perform a cooling operation or a heating operation in the indoor unit 2 based on an instruction from each indoor unit 2. That is, the air conditioning apparatus 100 can perform the same operation for all the indoor units 2 and can perform different operations for each of the indoor units 2.

The operation mode executed by the air conditioner 100 includes a cooling only operation mode in which all the driven indoor units 2 execute a cooling operation, and a heating only operation in which all the driven indoor units 2 execute a heating operation. There are a cooling main operation mode as a cooling / heating mixed operation mode with a larger mode and a cooling load, and a heating main operation mode as a cooling / heating mixed operation mode with a larger heating load. In addition to these four normal operations, the operation mode executed by the air-conditioning apparatus 100 according to Embodiment 1 includes a defrost operation mode in which frost attached to the heat source side heat exchanger 12 is removed.
Below, each operation mode is demonstrated with the flow of a heat-source side refrigerant | coolant and a heat medium.

[Cooling operation mode]
FIG. 3 is a refrigerant circuit diagram illustrating a refrigerant flow when the air-conditioning apparatus 100 is in the cooling only operation mode. In FIG. 3, the cooling only operation mode will be described by taking as an example a case where a cooling load is generated only in the use side heat exchanger 26a and the use side heat exchanger 26b. In addition, in FIG. 3, the piping represented with the thick line has shown the piping through which a refrigerant | coolant (a heat source side refrigerant | coolant and a heat medium) flows. In FIG. 3, the flow direction of the heat source side refrigerant is indicated by a solid line arrow, and the flow direction of the heat medium is indicated by a broken line arrow.

3, in the cooling only operation mode shown in FIG. 3, in the outdoor unit 1, the first refrigerant flow switching device 11 is switched so that the heat source side refrigerant discharged from the compressor 10 flows into the heat source side heat exchanger 12. In the heat medium converter 3, the pump 21a and the pump 21b are driven, the heat medium flow control device 25a and the heat medium flow control device 25b are opened, and the heat medium flow control device 25c and the heat medium flow control device 25d are fully closed. The heat medium circulates between the heat exchanger related to heat medium 15a and the heat exchanger related to heat medium 15b and the use side heat exchanger 26a and the use side heat exchanger 26b.

First, the flow of the heat source side refrigerant in the refrigerant circuit A will be described.
The low-temperature and low-pressure refrigerant is compressed by the compressor 10 and discharged as a high-temperature and high-pressure gas refrigerant. The high-temperature and high-pressure gas refrigerant discharged from the compressor 10 flows into the heat source side heat exchanger 12 via the first refrigerant flow switching device 11. And it becomes a high-pressure liquid refrigerant, radiating heat to outdoor air with the heat source side heat exchanger 12. The high-pressure refrigerant that has flowed out of the heat source side heat exchanger 12 flows out of the outdoor unit 1 through the check valve 13 a, and flows into the heat medium relay unit 3 through the refrigerant pipe 4. The high-pressure refrigerant flowing into the heat medium relay unit 3 is branched after passing through the opening / closing device 17a and expanded by the expansion device 16a and the expansion device 16b to become a low-temperature / low-pressure two-phase refrigerant. The opening / closing device 17b is closed.

This two-phase refrigerant flows into each of the heat exchanger related to heat medium 15a and the heat exchanger related to heat medium 15b acting as an evaporator, and absorbs heat from the heat medium circulating in the heat medium circulation circuit B. It becomes a low-temperature, low-pressure gas refrigerant while cooling. The gas refrigerant flowing out of the heat exchanger related to heat medium 15a and the heat exchanger related to heat medium 15b passes through the second refrigerant flow switching device 18a, the second refrigerant flow switching device 18b, and the heat medium converter 3, and is connected to the refrigerant pipe. 4 flows into the outdoor unit 1 again. The refrigerant flowing into the outdoor unit 1 passes through the check valve 13d and is sucked into the compressor 10 again via the first refrigerant flow switching device 11 and the accumulator 19.

At this time, the second refrigerant flow switching device 18a and the second refrigerant flow switching device 18b are communicated with the low pressure pipe. Further, the opening degree of the expansion device 16a is controlled so that the superheat (superheat degree) obtained as a difference between the temperature detected by the third temperature sensor 35a and the temperature detected by the third temperature sensor 35b becomes constant. Is done. Similarly, the opening degree of the expansion device 16b is controlled so that the superheat obtained as the difference between the temperature detected by the third temperature sensor 35c and the temperature detected by the third temperature sensor 35d is constant.

Next, the flow of the heat medium in the heat medium circuit B will be described.
In the cooling only operation mode, the cold heat of the heat source side refrigerant is transmitted to the heat medium in both the heat exchanger related to heat medium 15a and the heat exchanger related to heat medium 15b, and the cooled heat medium is piped 5 by the pump 21a and the pump 21b. The inside will be allowed to flow. The heat medium pressurized and discharged by the pump 21a and the pump 21b passes through the second heat medium flow switching device 23a and the second heat medium flow switching device 23b, and the use side heat exchanger 26a and the use side heat exchange. Flows into the vessel 26b. The heat medium absorbs heat from the indoor air in the use side heat exchanger 26a and the use side heat exchanger 26b, thereby cooling the indoor space 7.

Then, the heat medium flows out of the use-side heat exchanger 26a and the use-side heat exchanger 26b and flows into the heat medium flow control device 25a and the heat medium flow control device 25b. At this time, the heat medium flow control device 25a and the heat medium flow control device 25b control the flow rate of the heat medium to a flow rate necessary to cover the air conditioning load required in the room, so that the use-side heat exchanger 26a. And it flows into the use side heat exchanger 26b. The heat medium flowing out from the heat medium flow control device 25a and the heat medium flow control device 25b passes through the first heat medium flow switching device 22a and the first heat medium flow switching device 22b, and the heat exchanger related to heat medium 15a. And flows into the heat exchanger related to heat medium 15b, and is sucked into the pump 21a and the pump 21b again.

In the pipe 5 of the use side heat exchanger 26, the heat medium is directed from the second heat medium flow switching device 23 to the first heat medium flow switching device 22 via the heat medium flow control device 25. Flowing. The air conditioning load required in the indoor space 7 includes the temperature detected by the first temperature sensor 31a, the temperature detected by the first temperature sensor 31b, and the temperature detected by the second temperature sensor 34. By controlling so as to keep the difference between the two as a target value, it can be covered. As the outlet temperature of the heat exchanger related to heat medium 15, either the temperature of the first temperature sensor 31a or the first temperature sensor 31b may be used, or the average temperature thereof may be used. At this time, the first heat medium flow switching device 22 and the second heat medium flow switching device 23 ensure a flow path that flows to both the heat exchanger related to heat medium 15a and the heat exchanger related to heat medium 15b. In addition, the intermediate opening is set.

When the cooling only operation mode is executed, it is not necessary to flow the heat medium to the use side heat exchanger 26 (including the thermo-off) without the heat load. The heat medium is prevented from flowing to the heat exchanger 26. In FIG. 3, a heat medium flows because there is a heat load in the use side heat exchanger 26a and the use side heat exchanger 26b. However, in the use side heat exchanger 26c and the use side heat exchanger 26d, the heat load is supplied. The corresponding heat medium flow control device 25c and heat medium flow control device 25d are fully closed. When a heat load is generated from the use side heat exchanger 26c or the use side heat exchanger 26d, the heat medium flow control device 25c or the heat medium flow control device 25d is opened to circulate the heat medium. That's fine.

[Heating operation mode]
FIG. 4 is a refrigerant circuit diagram illustrating a refrigerant flow when the air-conditioning apparatus 100 is in the heating only operation mode. In FIG. 4, the heating only operation mode will be described by taking as an example a case where a thermal load is generated only in the use side heat exchanger 26a and the use side heat exchanger 26b. In FIG. 4, the pipes represented by the thick lines indicate the pipes through which the refrigerant (heat source side refrigerant and heat medium) flows. In FIG. 4, the flow direction of the heat source side refrigerant is indicated by solid line arrows, and the flow direction of the heat medium is indicated by broken line arrows.

In the heating only operation mode shown in FIG. 4, in the outdoor unit 1, the first refrigerant flow switching device 11 uses the heat source side refrigerant discharged from the compressor 10 without passing through the heat source side heat exchanger 12. It switches so that it may flow into converter 3. In the heat medium converter 3, the pump 21a and the pump 21b are driven, the heat medium flow control device 25a and the heat medium flow control device 25b are opened, and the heat medium flow control device 25c and the heat medium flow control device 25d are fully closed. The heat medium circulates between the heat exchanger related to heat medium 15a and the heat exchanger related to heat medium 15b and the use side heat exchanger 26a and the use side heat exchanger 26b.

First, the flow of the heat source side refrigerant in the refrigerant circuit A will be described.
The low-temperature and low-pressure refrigerant is compressed by the compressor 10 and discharged as a high-temperature and high-pressure gas refrigerant. The high-temperature and high-pressure gas refrigerant discharged from the compressor 10 flows out of the outdoor unit 1 through the first refrigerant flow switching device 11 and the check valve 13b. The high-temperature and high-pressure gas refrigerant that has flowed out of the outdoor unit 1 flows into the heat medium relay unit 3 through the refrigerant pipe 4. The high-temperature and high-pressure gas refrigerant that has flowed into the heat medium relay unit 3 is branched and passes through the second refrigerant flow switching device 18a and the second refrigerant flow switching device 18b, and the heat exchanger related to heat medium 15a and the heat medium. It flows into each of the intermediate heat exchangers 15b.

The high-temperature and high-pressure gas refrigerant flowing into the heat exchanger related to heat medium 15a and the heat exchanger related to heat medium 15b becomes a high-pressure liquid refrigerant while dissipating heat to the heat medium circulating in the heat medium circuit B. The liquid refrigerant flowing out of the heat exchanger related to heat medium 15a and the heat exchanger related to heat medium 15b is expanded by the expansion device 16a and the expansion device 16b to become a low-temperature, low-pressure two-phase refrigerant. The two-phase refrigerant flows out of the heat medium relay unit 3 through the opening / closing device 17b, and flows into the outdoor unit 1 through the refrigerant pipe 4 again. The opening / closing device 17a is closed.

The refrigerant flowing into the outdoor unit 1 passes through the check valve 13c and flows into the heat source side heat exchanger 12 acting as an evaporator. And the refrigerant | coolant which flowed into the heat source side heat exchanger 12 absorbs heat from outdoor air in the heat source side heat exchanger 12, and becomes a low-temperature and low-pressure gas refrigerant. The low-temperature and low-pressure gas refrigerant flowing out from the heat source side heat exchanger 12 is again sucked into the compressor 10 via the first refrigerant flow switching device 11 and the accumulator 19.

At this time, the second refrigerant flow switching device 18a and the second refrigerant flow switching device 18b are in communication with the high-pressure pipe. Further, the expansion device 16a has a constant subcool (degree of subcooling) obtained as a difference between a value obtained by converting the pressure detected by the pressure sensor 36a into a saturation temperature and a temperature detected by the third temperature sensor 35b. The opening degree is controlled. Similarly, the expansion device 16b has an opening degree so that a subcool obtained as a difference between a value obtained by converting the pressure detected by the pressure sensor 36b into a saturation temperature and a temperature detected by the third temperature sensor 35d is constant. Be controlled. When the temperature at the intermediate position of the heat exchanger related to heat medium 15 can be measured, the temperature at the intermediate position may be used instead of the pressure sensor 36, and the system can be configured at low cost.

Next, the flow of the heat medium in the heat medium circuit B will be described.
In the heating only operation mode, the heat of the heat source side refrigerant is transmitted to the heat medium in both the heat exchanger 15a and the heat exchanger 15b, and the heated heat medium is piped 5 by the pump 21a and the pump 21b. The inside will be allowed to flow. The heat medium pressurized and discharged by the pump 21a and the pump 21b passes through the second heat medium flow switching device 23a and the second heat medium flow switching device 23b, and the use side heat exchanger 26a and the use side heat exchange. Flows into the vessel 26b. The heat medium radiates heat to the indoor air in the use side heat exchanger 26a and the use side heat exchanger 26b, thereby heating the indoor space 7.

In the pipe 5 of the use side heat exchanger 26, the heat medium is directed from the second heat medium flow switching device 23 to the first heat medium flow switching device 22 via the heat medium flow control device 25. Flowing. The air conditioning load required in the indoor space 7 includes the temperature detected by the first temperature sensor 31a, the temperature detected by the first temperature sensor 31b, and the temperature detected by the second temperature sensor 34. By controlling so as to keep the difference between the two as a target value, it can be covered. As the outlet temperature of the heat exchanger related to heat medium 15, either the temperature of the first temperature sensor 31a or the first temperature sensor 31b may be used, or the average temperature thereof may be used.

At this time, the first heat medium flow switching device 22 and the second heat medium flow switching device 23 ensure a flow path that flows to both the heat exchanger related to heat medium 15a and the heat exchanger related to heat medium 15b. In addition, the intermediate opening is set. In addition, the usage-side heat exchanger 26a should be controlled by the temperature difference between the inlet and the outlet, but the temperature of the heat medium on the inlet side of the usage-side heat exchanger 26 is detected by the first temperature sensor 31b. By using the first temperature sensor 31b, the number of temperature sensors can be reduced and the system can be configured at low cost.

When the heating only operation mode is executed, it is not necessary to flow the heat medium to the use side heat exchanger 26 (including the thermo-off) without the heat load. The heat medium is prevented from flowing to the heat exchanger 26. In FIG. 4, a heat medium flows because there is a heat load in the use side heat exchanger 26a and the use side heat exchanger 26b. However, in the use side heat exchanger 26c and the use side heat exchanger 26d, the heat load is passed. The corresponding heat medium flow control device 25c and heat medium flow control device 25d are fully closed. When a heat load is generated from the use side heat exchanger 26c or the use side heat exchanger 26d, the heat medium flow control device 25c or the heat medium flow control device 25d is opened to circulate the heat medium. That's fine.

[Cooling operation mode]
FIG. 5 is a refrigerant circuit diagram illustrating a refrigerant flow when the air-conditioning apparatus 100 is in the cooling main operation mode. In FIG. 5, the cooling main operation mode will be described by taking as an example a case where a cooling load is generated in the use side heat exchanger 26a and a heating load is generated in the use side heat exchanger 26b. Note that in FIG. 5, a pipe represented by a thick line shows a pipe through which the refrigerant (heat source side refrigerant and heat medium) circulates. Further, in FIG. 5, the flow direction of the heat source side refrigerant is indicated by solid line arrows, and the flow direction of the heat medium is indicated by broken line arrows.

In the cooling main operation mode shown in FIG. 5, in the outdoor unit 1, the first refrigerant flow switching device 11 is switched so that the heat source side refrigerant discharged from the compressor 10 flows into the heat source side heat exchanger 12. In the heat medium converter 3, the pump 21a and the pump 21b are driven, the heat medium flow control device 25a and the heat medium flow control device 25b are opened, and the heat medium flow control device 25c and the heat medium flow control device 25d are fully closed. The heat medium is circulated between the heat exchanger related to heat medium 15a and the use side heat exchanger 26a, and between the heat exchanger related to heat medium 15b and the use side heat exchanger 26b.

First, the flow of the heat source side refrigerant in the refrigerant circuit A will be described.
The low-temperature and low-pressure refrigerant is compressed by the compressor 10 and discharged as a high-temperature and high-pressure gas refrigerant. The high-temperature and high-pressure gas refrigerant discharged from the compressor 10 flows into the heat source side heat exchanger 12 via the first refrigerant flow switching device 11. And it becomes a liquid refrigerant, dissipating heat to outdoor air with the heat source side heat exchanger 12. The refrigerant that has flowed out of the heat source side heat exchanger 12 flows out of the outdoor unit 1 and flows into the heat medium relay unit 3 through the check valve 13 a and the refrigerant pipe 4. The refrigerant that has flowed into the heat medium relay unit 3 flows into the heat exchanger related to heat medium 15b that acts as a condenser through the second refrigerant flow switching device 18b.

The refrigerant that has flowed into the heat exchanger related to heat medium 15b becomes a refrigerant whose temperature is further lowered while radiating heat to the heat medium circulating in the heat medium circuit B. The refrigerant flowing out of the heat exchanger related to heat medium 15b is expanded by the expansion device 16b and becomes a low-pressure two-phase refrigerant. This low-pressure two-phase refrigerant flows into the heat exchanger related to heat medium 15a acting as an evaporator via the expansion device 16a. The low-pressure two-phase refrigerant that has flowed into the heat exchanger related to heat medium 15a absorbs heat from the heat medium circulating in the heat medium circuit B, and becomes a low-pressure gas refrigerant while cooling the heat medium. The gas refrigerant flows out of the heat exchanger related to heat medium 15a, flows out of the heat medium converter 3 via the second refrigerant flow switching device 18a, and flows into the outdoor unit 1 again through the refrigerant pipe 4. The refrigerant that has flowed into the outdoor unit 1 is again sucked into the compressor 10 via the check valve 13d, the first refrigerant flow switching device 11, and the accumulator 19.

At this time, the second refrigerant flow switching device 18a is in communication with the low pressure pipe, while the second refrigerant flow switching device 18b is in communication with the high pressure side piping. Further, the opening degree of the expansion device 16b is controlled so that the superheat obtained as the difference between the temperature detected by the third temperature sensor 35a and the temperature detected by the third temperature sensor 35b becomes constant. Further, the expansion device 16a is fully opened and the opening / closing device 17b is closed. The expansion device 16b controls the opening degree so that a subcool obtained as a difference between a value obtained by converting the pressure detected by the pressure sensor 36 into a saturation temperature and a temperature detected by the third temperature sensor 35d is constant. May be. Alternatively, the expansion device 16b may be fully opened, and the superheat or subcool may be controlled by the expansion device 16a.

Next, the flow of the heat medium in the heat medium circuit B will be described.
In the cooling main operation mode, the heat of the heat source side refrigerant is transmitted to the heat medium in the heat exchanger related to heat medium 15b, and the heated heat medium is caused to flow in the pipe 5 by the pump 21b. In the cooling main operation mode, the cold heat of the heat source side refrigerant is transmitted to the heat medium by the heat exchanger related to heat medium 15a, and the cooled heat medium is caused to flow in the pipe 5 by the pump 21a. The heat medium pressurized and discharged by the pump 21a and the pump 21b passes through the second heat medium flow switching device 23a and the second heat medium flow switching device 23b, and the use side heat exchanger 26a and the use side heat exchange. Flows into the vessel 26b.

In the use side heat exchanger 26b, the heat medium radiates heat to the indoor air, thereby heating the indoor space 7. In the use-side heat exchanger 26a, the indoor space 7 is cooled by the heat medium absorbing heat from the indoor air. At this time, the heat medium flow control device 25a and the heat medium flow control device 25b control the flow rate of the heat medium to a flow rate necessary to cover the air conditioning load required in the room, so that the use-side heat exchanger 26a. And it flows into the use side heat exchanger 26b. The heat medium whose temperature has slightly decreased after passing through the use side heat exchanger 26b flows into the heat exchanger related to heat medium 15b through the heat medium flow control device 25b and the first heat medium flow switching device 22b, and again. It is sucked into the pump 21b. The heat medium whose temperature has slightly increased after passing through the use side heat exchanger 26a flows into the heat exchanger related to heat medium 15a through the heat medium flow control device 25a and the first heat medium flow switching device 22a, and again. It is sucked into the pump 21a.

During this time, the warm heat medium and the cold heat medium are not mixed by the action of the first heat medium flow switching device 22 and the second heat medium flow switching device 23, and the use side has a heat load and a heat load, respectively. It is introduced into the heat exchanger 26. In the pipe 5 of the use side heat exchanger 26, the first heat medium flow switching device 22 from the second heat medium flow switching device 23 via the heat medium flow control device 25 on both the heating side and the cooling side. The heat medium is flowing in the direction to The air conditioning load required in the indoor space 7 is the difference between the temperature detected by the first temperature sensor 31b on the heating side and the temperature detected by the second temperature sensor 34 on the heating side, This can be covered by controlling the difference between the temperature detected by the two temperature sensor 34 and the temperature detected by the first temperature sensor 31a as a target value.

When executing the cooling main operation mode, it is not necessary to flow the heat medium to the use side heat exchanger 26 (including the thermo-off) without the heat load, so the flow path is closed by the heat medium flow control device 25 and the use side The heat medium is prevented from flowing to the heat exchanger 26. In FIG. 5, a heat medium flows because there is a heat load in the use side heat exchanger 26a and the use side heat exchanger 26b. However, in the use side heat exchanger 26c and the use side heat exchanger 26d, the heat load is supplied. The corresponding heat medium flow control device 25c and heat medium flow control device 25d are fully closed. When a heat load is generated from the use side heat exchanger 26c or the use side heat exchanger 26d, the heat medium flow control device 25c or the heat medium flow control device 25d is opened to circulate the heat medium. That's fine.

[Heating main operation mode]
FIG. 6 is a refrigerant circuit diagram showing a refrigerant flow when the air-conditioning apparatus 100 is in the heating main operation mode. In FIG. 6, the heating main operation mode will be described by taking as an example a case where a thermal load is generated in the use side heat exchanger 26a and a cold load is generated in the use side heat exchanger 26b. In addition, in FIG. 6, the piping represented with the thick line has shown the piping through which a refrigerant | coolant (a heat-source side refrigerant | coolant and a heat medium) circulates. In FIG. 6, the flow direction of the heat source side refrigerant is indicated by solid line arrows, and the flow direction of the heat medium is indicated by broken line arrows.

In the heating-main operation mode shown in FIG. 6, in the outdoor unit 1, the first refrigerant flow switching device 11 uses the heat source side refrigerant discharged from the compressor 10 without passing through the heat source side heat exchanger 12. It switches so that it may flow into converter 3. In the heat medium converter 3, the pump 21a and the pump 21b are driven, the heat medium flow control device 25a and the heat medium flow control device 25b are opened, and the heat medium flow control device 25c and the heat medium flow control device 25d are fully closed. The heat medium circulates between the heat exchanger related to heat medium 15a and the use-side heat exchanger 26b, and between the heat exchanger related to heat medium 15b and the use-side heat exchanger 26a.

First, the flow of the heat source side refrigerant in the refrigerant circuit A will be described.
The low-temperature and low-pressure refrigerant is compressed by the compressor 10 and discharged as a high-temperature and high-pressure gas refrigerant. The high-temperature and high-pressure gas refrigerant discharged from the compressor 10 flows out of the outdoor unit 1 through the first refrigerant flow switching device 11 and the check valve 13b. The high-temperature and high-pressure gas refrigerant that has flowed out of the outdoor unit 1 flows into the heat medium relay unit 3 through the refrigerant pipe 4. The high-temperature and high-pressure gas refrigerant that has flowed into the heat medium relay unit 3 flows into the heat exchanger related to heat medium 15b that acts as a condenser through the second refrigerant flow switching device 18b.

The gas refrigerant flowing into the heat exchanger related to heat medium 15b becomes liquid refrigerant while dissipating heat to the heat medium circulating in the heat medium circuit B. The refrigerant flowing out of the heat exchanger related to heat medium 15b is expanded by the expansion device 16b and becomes a low-pressure two-phase refrigerant. This low-pressure two-phase refrigerant flows into the heat exchanger related to heat medium 15a acting as an evaporator via the expansion device 16a. The low-pressure two-phase refrigerant that has flowed into the heat exchanger related to heat medium 15a evaporates by absorbing heat from the heat medium circulating in the heat medium circuit B, thereby cooling the heat medium. The low-pressure two-phase refrigerant flows out of the heat exchanger related to heat medium 15a, flows out of the heat medium converter 3 through the second refrigerant flow switching device 18a, and flows into the outdoor unit 1 again.

At this time, the second refrigerant flow switching device 18a is in communication with the low pressure side piping, while the second refrigerant flow switching device 18b is in communication with the high pressure side piping. Further, the opening of the expansion device 16b is controlled so that a subcool obtained as a difference between a value obtained by converting the pressure detected by the pressure sensor 36b into a saturation temperature and a temperature detected by the third temperature sensor 35b is constant. Is done. Further, the expansion device 16a is fully opened, and the opening / closing device 17a is closed. Note that the expansion device 16b may be fully opened, and the subcooling may be controlled by the expansion device 16a.

Next, the flow of the heat medium in the heat medium circuit B will be described.
In the heating main operation mode, the heat of the heat source side refrigerant is transmitted to the heat medium in the heat exchanger related to heat medium 15b, and the heated heat medium is caused to flow in the pipe 5 by the pump 21b. In the heating main operation mode, the cold heat of the heat source side refrigerant is transmitted to the heat medium by the heat exchanger related to heat medium 15a, and the cooled heat medium is caused to flow in the pipe 5 by the pump 21a. The heat medium pressurized and discharged by the pump 21a and the pump 21b passes through the second heat medium flow switching device 23a and the second heat medium flow switching device 23b, and the use side heat exchanger 26a and the use side heat exchange. Flows into the vessel 26b.

In the use side heat exchanger 26b, the heat medium absorbs heat from the indoor air, thereby cooling the indoor space 7. Moreover, in the use side heat exchanger 26a, the heat medium radiates heat to the indoor air, thereby heating the indoor space 7. At this time, the heat medium flow control device 25a and the heat medium flow control device 25b control the flow rate of the heat medium to a flow rate necessary to cover the air conditioning load required in the room, so that the use-side heat exchanger 26a. And it flows into the use side heat exchanger 26b. The heat medium whose temperature has slightly increased after passing through the use side heat exchanger 26b flows into the heat exchanger related to heat medium 15a through the heat medium flow control device 25b and the first heat medium flow switching device 22b, and again. It is sucked into the pump 21a. The heat medium whose temperature has slightly decreased after passing through the use side heat exchanger 26a flows into the heat exchanger related to heat medium 15b through the heat medium flow control device 25a and the first heat medium flow switching device 22a, and again. It is sucked into the pump 21b.

When the heating main operation mode is executed, it is not necessary to flow the heat medium to the use side heat exchanger 26 (including the thermo-off) without the heat load, so the flow path is closed by the heat medium flow control device 25 and the use side The heat medium is prevented from flowing to the heat exchanger 26. In FIG. 6, since there is a heat load in the use-side heat exchanger 26a and the use-side heat exchanger 26b, a heat medium is flowing, but in the use-side heat exchanger 26c and the use-side heat exchanger 26d, the heat load is passed. The corresponding heat medium flow control device 25c and heat medium flow control device 25d are fully closed. When a heat load is generated from the use side heat exchanger 26c or the use side heat exchanger 26d, the heat medium flow control device 25c or the heat medium flow control device 25d is opened to circulate the heat medium. That's fine.

[Defrost operation mode 1]
FIG. 7 is a refrigerant circuit diagram illustrating a refrigerant flow when the air-conditioning apparatus 100 according to the embodiment of the present invention is in the defrosting operation mode. In FIG. 7, the flow direction of the heat source side refrigerant is indicated by a solid line arrow, and the flow direction of the heat medium is indicated by a broken line arrow.

The defrost operation mode 1 according to the present embodiment is performed when the detection result of the first outdoor temperature sensor 40a is equal to or less than a first predetermined value. That is, when the air-conditioning apparatus 100 performs the heating only operation or the heating main operation, and the detection result of the first outdoor temperature sensor 40a is equal to or lower than the first predetermined value, the control device 70 is applied to the fins of the heat source side heat exchanger 12. It is determined that a predetermined amount of frost formation has occurred, and the defrost operation mode 1 is entered. In the description of the present embodiment, it is assumed that all four indoor units 2a to 2d are performing the heating operation. The first predetermined value may be set to a temperature at which frost formation occurs on the heat source side heat exchanger 12, for example, about −10 ° C. or less.

In the defrost operation mode 1 of the air-conditioning apparatus 100 according to the present embodiment, in the outdoor unit 1, the blower (not shown) is stopped, and the first refrigerant flow switching device 11 is replaced with the heat source side refrigerant discharged from the compressor 10. Is switched to flow into the heat source side heat exchanger 12. In the heat medium relay unit 3, the opening / closing devices 17a and 17b are opened, the second refrigerant flow switching devices 18a and 18b are switched to the heating side, and the

expansion devices

16a and 16b are fully closed.
In the defrost operation mode 1 of the air conditioner 100 according to the present embodiment, the heating operation of the indoor units 2a to 2d is continued. That is, the heat medium is conveyed to the four indoor units 2a to 2d and the operation of the blower fan attached to the four indoor units 2a to 2d is continued. Specifically, in the heat medium relay unit 3, the

pumps

21a and 21b are driven, the first heat medium flow switching devices 22a to 22d, the second heat medium flow switching devices 23a to 23d, and the heat medium flow rate adjustment. The devices 25a to 25d are opened, and the heat medium is circulated between the heat exchangers between

heat mediums

15a and 15b and the use side heat exchangers 26a to 26d.

In addition, when there is no request for heating operation or there is an indoor unit 2 that is stopped, the indoor unit is arranged so as not to convey the heat medium to the use side heat exchanger 26 corresponding to the indoor unit 2. The heat medium flow control device 25 corresponding to 2 may be closed.
When all four indoor units 2a to 2d do not require heating operation or are stopped, the blower (not shown) installed in the indoor unit 2 is stopped and the four heat mediums are stopped. The heat medium may be circulated by opening the flow rate adjusting devices 25a to 25d. Thereby, it can suppress that the refrigerant | coolant of the refrigerant circuit A which flowed into the heat exchanger 15 between heat media freezes the heat medium of the heat medium circuit B.

First, the flow of the heat source side refrigerant in the refrigerant circuit A will be described.
The low-temperature and low-pressure refrigerant is compressed by the compressor 10 and discharged as a high-temperature and high-pressure gas refrigerant. The high-temperature and high-pressure gas refrigerant discharged from the compressor 10 flows into the heat source side heat exchanger 12 via the first refrigerant flow switching device 11. Then, the frost formed on the fins of the heat source side heat exchanger 12 becomes a supercooled liquid or a two-phase refrigerant while dissipating heat, and the frost formed on the fins of the heat source side heat exchanger 12 is removed. The high-pressure refrigerant that has flowed out of the heat source side heat exchanger 12 flows out of the outdoor unit 1 through the check valve 13a, and flows into the heat medium relay unit 3 through the refrigerant pipe 4.

One of the high-pressure refrigerants that has flowed into the heat medium relay unit 3 is reduced in pressure by passing through the switchgear 17a and the switchgear 17b to become a low-pressure two-phase refrigerant. And this low-pressure two-phase refrigerant is again outdoors through the bypass refrigerant pipe 4c and the refrigerant pipe 4 without circulating through the refrigerant side flow paths of the heat exchanger related to heat medium 15a and the heat exchanger related to heat medium 15b. It flows into the machine 1. The refrigerant flowing into the outdoor unit 1 is again sucked into the compressor 10 via the check valve 13d, the first refrigerant flow switching device 11, and the accumulator 19.
On the other hand, the other of the high-pressure refrigerant that has flowed into the heat medium relay unit 3 flows into the

heat exchangers

15a and 15b via the second refrigerant flow switching devices 18a and 18b.

When the second outdoor temperature sensor 40b detects the second predetermined value or more, the control device 70 ends the defrost operation mode 1 and shifts again to the heating only operation mode or the heating main operation mode. The second predetermined value may be set to a temperature at which it can be determined that the frost in the heat source side heat exchanger 12 has been removed, for example, about 30 ° C. or higher.
Moreover, although it described that it transfers to a heating only operation mode or the heating main operation mode after completion | finish of the defrost operation mode 1, for example, when there exists an instruction | indication which performs other operation modes from those, according to the instruction | indication Execute the selected operation mode.

7, in the defrost operation mode 1, the second refrigerant flow switching devices 18a and 18b communicate with the high-pressure pipe. Thereby, the refrigerant that has flowed into the heat exchanger related to

heat medium

15a, 15b from the side where the second refrigerant flow switching devices 18a, 18b are connected is approximately equal to the pressure of the heat-source-side refrigerant flowing into the heat medium converter 3. Equal supercooled liquid or two-phase refrigerant. The refrigerant flowing into the

intermediate heat exchangers

15a and 15b has a high saturation temperature due to its high pressure, and the saturation temperature is 0 ° C. or higher. Thereby, it is suppressed that the

heat exchangers

15a and 15b between heat media cool to the low temperature below 0 degreeC. That is, since the heat medium is prevented from freezing due to the refrigerant flowing into the heat exchangers between

heat mediums

15a and 15b, the operation reliability of the air conditioner 100 can be improved.

Here, the case where there is refrigerant leakage in the

expansion devices

16a and 16b will be described. If the refrigerant flows in the direction from the

expansion devices

16a and 16b toward the

heat exchangers

15a and 15b, the pressure is reduced by the operation of the

expansion devices

16a and 16b, and the saturation temperature of the refrigerant is 0 ° C. or lower. May be reduced. In other words, when the decompressed refrigerant flows into the

heat exchangers

15a and 15b, the

heat exchangers

15a and 15b may be cooled to a low temperature of 0 ° C. or lower and the heat medium may be frozen. There is sex.
However, in the air conditioner 100 according to the present embodiment, the side connected to the

heat exchangers

15a and 15b among the

expansion devices

16a and 16b has a high pressure. This prevents the refrigerant from flowing from the

expansion devices

16a, 16b toward the

heat exchangers

15a, 15b even if the refrigerant leaks in the

expansion devices

16a, 16b. That is, even if the refrigerant leaks in the

expansion devices

16a and 16b, the refrigerant flows into the

heat exchangers

15a and 15b from the

expansion devices

16a and 16b, and the freezing of the heat medium is suppressed. That's what it means.

Next, the flow of the heat medium in the heat medium circuit B will be described.
In the defrost operation mode 1 of the air conditioner 100 according to the present embodiment, the heat medium is caused to flow in the pipe 5 by the

pumps

21a and 21b. That is, the heat medium pressurized and discharged by the

pumps

21a and 21b flows into the use side heat exchangers 26a to 26d via the second heat medium flow switching devices 23a to 23d. The heat medium flowing into the use side heat exchangers 26a to 26d stores the heat generated in the full warm operation mode before the transition to the defrost operation mode 1. Therefore, the heating operation can be continued by conveying the heat medium to the use side heat exchangers 26a to 26d.
The heat medium flowing out from the use side heat exchangers 26a to 26d flows into the heat exchangers between

heat mediums

15a and 15b via the heat medium flow control devices 25a to 25d and the first heat medium flow switching devices 22a to 22d. The heat medium flowing out from the heat exchangers between

heat mediums

15a and 15b is sucked into the

pumps

21a and 21b again.
As described above, the air-conditioning apparatus 100 according to the present embodiment circulates a heat medium such as water or antifreeze liquid in the heat medium circulation circuit B, so that the heat exchangers between

heat mediums

15a and 15b are in the defrost operation mode 1. It is possible to prevent the heat medium from being frozen by the heat source side refrigerant flowing in. Thereby, the operation | movement reliability of the air conditioning apparatus 100 can be improved.

In addition, in FIG. 7, it demonstrated and demonstrated as an example the case where it transfers to a defrost operation from a full warm operation mode. If the heating main operation mode is shifted to the defrost operation, the cooling medium and the heating operation of the indoor space 7 are continued by changing the flow of the heat medium in the heat medium circuit B to the flow of the heating main operation mode. I can do it.

[Defrost operation mode 2]
FIG. 8 is a refrigerant circuit diagram showing a refrigerant flow in the defrost operation mode 2-1, which is one of the five defrost operation modes 2. FIG. 9 is a refrigerant circuit diagram showing a refrigerant flow in the defrost operation mode 2-5, which is one form of the defrost operation mode 2. The air conditioner 100 includes five operation modes as a defrost operation mode 2 different from the defrost operation mode 1.
That is, the defrosting operation mode 2 includes “defrosting operation mode 2-1 in which the switching device 17a is closed and the mode is changed from the heating only operation mode, and the refrigerant is circulated through both the

heat exchangers

15a and 15b”, Close the device 17a, shift from the heating main operation mode, defrost operation mode 2-2 in which the refrigerant is circulated only to the heat exchanger related to heat medium 15b, "open and close the switchgear 17a, shift from the heating only operation mode, “Defrost operation mode 2-3 in which refrigerant is circulated through both

heat exchangers

15a and 15b” and “Opening and closing device 17a is opened to shift from the heating main operation mode, and refrigerant is supplied only to heat exchanger 15b. Defrost operation mode 2-4 that circulates the refrigerant, and "defrost that makes a transition from the heating-main operation mode and circulates refrigerant to both the

heat exchangers

15a and 15b. And an operation mode 2-5 ".
Similarly to the defrost operation mode 1, the defrost operation mode 2 is performed when the detection result of the first outdoor temperature sensor 40a is equal to or less than the first predetermined value. That is, when the air-conditioning apparatus 100 performs the heating only operation or the heating main operation, and the detection result of the first outdoor temperature sensor 40a is equal to or lower than the first predetermined value, the control device 70 is applied to the fins of the heat source side heat exchanger 12. It is determined that a predetermined amount of frost formation has occurred, and the defrost operation mode 2 is entered.
When it is desired to shorten the defrosting time, this defrost operation mode 2 may be adopted rather than the defrost operation mode 1.

(Defrost operation mode 2-1)
In the defrost operation mode 2-1 of the air-conditioning apparatus 100 according to the present embodiment, in the outdoor unit 1, the blower (not shown) is stopped, and the first refrigerant flow switching device 11 is used as the heat source discharged from the compressor 10. The side refrigerant is switched to flow into the heat source side heat exchanger 12. In the heat medium relay unit 3, the opening / closing device 17a is closed, the opening / closing device 17b is opened, the second refrigerant flow switching device 18 is switched to the heating side, and the expansion device 16 is opened.
Also, in the defrost operation mode 2-1 of the air-conditioning apparatus 100 according to the present embodiment, the heating operation of the indoor units 2 a to 2 d is continued as in the embodiment. That is, in the heat medium relay unit 3, the

pumps

21a and 21b are driven, and the first heat medium flow switching devices 22a to 22d, the second heat medium flow switching devices 23a to 23d, and the heat medium flow control devices 25a to 25d. And the heat medium is circulated between the heat exchangers between

heat exchangers

15a and 15b and the use side heat exchangers 26a to 26d.

In addition, when there is no request for heating operation or there is an indoor unit 2 that is stopped, the indoor unit is arranged so as not to convey the heat medium to the use side heat exchanger 26 corresponding to the indoor unit 2. The heat medium flow control device 25 corresponding to 2 may be closed.
When all four indoor units 2a to 2d do not require heating operation or are stopped, the blower (not shown) installed in the indoor unit 2 is stopped and the four heat mediums are stopped. The heat medium may be circulated by opening the flow rate adjusting devices 25a to 25d.

First, the flow of the heat source side refrigerant in the refrigerant circuit A will be described.
The low-temperature and low-pressure refrigerant is compressed by the compressor 10 and discharged as a high-temperature and high-pressure gas refrigerant. The high-temperature and high-pressure gas refrigerant discharged from the compressor 10 flows into the heat source side heat exchanger 12 via the first refrigerant flow switching device 11. Then, the frost formed on the fins of the heat source side heat exchanger 12 becomes a supercooled liquid or a two-phase refrigerant while dissipating heat, and the frost formed on the fins of the heat source side heat exchanger 12 is removed. The high-pressure refrigerant that has flowed out of the heat source side heat exchanger 12 flows out of the outdoor unit 1 through the check valve 13 a, and flows into the heat medium relay unit 3 through the refrigerant pipe 4.

The supercooled liquid or two-phase refrigerant that has flowed into the heat medium relay unit 3 flows into the

heat exchangers

15a and 15b, and after absorbing heat from the heat medium, the throttling device 16a having an opening degree close to or fully open. It is expanded at 16b and becomes a low-pressure two-phase refrigerant. The low-pressure two-phase refrigerant again flows into the outdoor unit 1 through the bypass refrigerant pipe 4c and the refrigerant pipe 4. The refrigerant flowing into the outdoor unit 1 is again sucked into the compressor 10 via the check valve 13d, the first refrigerant flow switching device 11, and the accumulator 19.
When the second outdoor temperature sensor 40b detects the second predetermined value or more, the control device 70 ends the defrost operation mode 2-1, and again shifts to the heating only operation mode or the heating main operation mode. . The second predetermined value may be set to about 30 ° C. or higher, for example.

As shown in FIG. 8, in the defrost operation mode 2-1, the second refrigerant flow switching devices 18a and 18b communicate with the high-pressure pipe. Thereby, the refrigerant that has flowed into the

heat exchangers

15a, 15b from one of the

heat exchangers

15a, 15b is a supercooled liquid that is substantially equal to the pressure of the heat source refrigerant flowing into the heat exchanger 3; Or it is a two-phase refrigerant. The supercooled liquid or the two-phase refrigerant has a saturation temperature of about 0 ° C. or higher. Further, the heat medium in the heat medium circuit B is heated to about 20 ° C. or more by the heating only operation mode before the defrost operation mode 2-1.
Therefore, in the heat exchangers between

heat mediums

15a and 15b, the refrigerant in the refrigerant circuit A absorbs heat from the heat medium in the heat medium circuit B, so that among the low-pressure two-phase refrigerants flowing out from the

expansion devices

16a and 16b, The proportion occupied by the gas layer increases. That is, the ratio of the low-temperature and low-pressure gas refrigerant to the refrigerant sucked into the compressor 10 increases. Thereby, the heat capacity of the high-temperature and high-pressure gas refrigerant discharged from the compressor 10 is increased, and the defrosting operation time of the heat source side heat exchanger 12 can be shortened.

Note that the temperature of the refrigerant flowing into the

heat exchangers

15a and 15b between the heat mediums is about 0 ° C. or higher, and the cooling of the heat medium to a low temperature of 0 ° C. or lower is suppressed. That is, the heat medium is prevented from freezing due to the refrigerant flowing into the heat exchangers between

heat mediums

15a and 15b.

Next, the flow of the heat medium in the heat medium circuit B will be described.
Also in the defrosting operation mode 2-1 of the air conditioner 100 according to the present embodiment, the heat medium is caused to flow in the pipe 5 by the

pumps

21a and 21b. That is, the heat medium pressurized and discharged by the

pumps

21a and 21b flows into the use side heat exchangers 26a to 26d via the second heat medium flow switching devices 23a to 23d. The heat medium flowing into the use side heat exchangers 26a to 26d stores the heat generated in the full warm operation mode before the transition to the defrost operation mode 2-1. Therefore, the heating operation can be continued by conveying the heat medium to the use side heat exchangers 26a to 26d.
The heat medium flowing out from the use side heat exchangers 26a to 26d flows into the heat exchangers between

heat mediums

15a and 15b is sucked into the

pumps

21a and 21b again.
In this way, by circulating a heat medium such as water or antifreeze in the heat medium circuit B, the heat source side refrigerant flowing into the heat exchangers between

heat mediums

15a and 15b in the defrost operation mode 2-1 generates heat. It is possible to prevent the medium from freezing.

(Defrost operation mode 2-2)
Next, the defrost operation mode 2-2 for performing the defrost operation from the heating main operation mode shown in FIG. 6 will be described. Here, the case where heating is required for the indoor unit 2a and the cooling is required for the indoor unit 2b will be described as an example.
When shifting from the heating-main operation mode to the defrost operation mode 2-2, the expansion device 16a is fully closed, or the opening is such that the refrigerant does not flow, and the heat exchanger related to heat medium 15a that has generated cold for cooling is used. Thus, the expansion device 16b is opened, and the heat exchanger related to heat medium 15b in which the heat is generated for heating circulates the refrigerant. Moreover, about 2nd refrigerant | coolant flow path switching device 18a, 18b, both are switched to the heating side, and are connected with a high voltage | pressure piping.
The flow of the heat medium in the heat medium circulation circuit B is the flow in the heating main operation mode, and is generated in the heat exchanger related to heat medium 15a in the heating main operation mode before the transition to the defrost operation mode 2-2. It is possible to continue the cooling operation and the heating operation of the indoor space 7 using the cold heat and the heat generated by the heat exchanger related to heat medium 15b.

The refrigerant flowing into the heat exchanger related to

heat medium

15a, 15b via the second refrigerant flow switching devices 18a, 18b is a supercooled liquid substantially equal to the pressure of the heat source side refrigerant flowing into the heat medium converter 3, or two It is a phase refrigerant. The supercooled liquid or the two-phase refrigerant has a saturation temperature of about 0 ° C. or higher. Further, the heat medium in the heat medium circulation circuit B is heated to about 20 ° C. or more by the heat exchanger related to heat medium 15b in the heating main operation mode before the defrost operation mode 2-2. The temperature of the refrigerant flowing into the heat exchangers between

heat mediums

15a and 15b is about 0 ° C. or higher, and the cooling of the heat medium to a low temperature of 0 ° C. or lower is suppressed. That is, it is suppressed that the heat medium freezes due to the refrigerant flowing into the heat exchanger related to heat medium 15b.

(Defrost operation mode 2-3)
Although the defrosting operation mode 2-1 has been described as closing the opening / closing device 17a, the defrosting operation mode 2-3 may be performed. That is, the defrosting operation mode 2-3 is a defrosting operation mode for shifting from the heating only operation mode, and the opening / closing device 17a is open. Here, the case where heating is required for the indoor unit 2a and the cooling is required for the indoor unit 2b will be described as an example.
In the defrost operation mode 2-3, in order to open the opening / closing device 17a, the heat source side refrigerant flowing out from the expansion device 16a via the second refrigerant flow switching device 18a and the heat exchanger related to heat medium 15a, and the second refrigerant The heat-source-side refrigerant flowing out of the expansion device 16b and the heat-source-side refrigerant flowing in from the opening / closing device 17a merge through the flow path switching device 18b and the heat exchanger related to heat medium 15b. Thereafter, the merged refrigerant flows out of the heat medium relay unit 3 through the opening / closing device 17b and the bypass refrigerant pipe 4c.

Thus, even if the opening / closing device 17a is opened, the refrigerant that has flowed into the heat medium converter 3 and passed through the opening / closing device 17a merges with the refrigerant that flows out of the

expansion devices

16a, 16b. Here, when the opening / closing device 17a is opened, there is a heat source side refrigerant flowing into the bypass refrigerant pipe 4c via the opening / closing device 17a, so the second refrigerant flow switching device 18 and the heat exchanger related to heat medium 15 have The circulating amount of refrigerant flowing in is reduced, and the pressure loss of the heat source side refrigerant is reduced. And since the pressure loss of the heat source side refrigerant can be reduced, the refrigerant pressure in the

heat exchangers

15a and 15b can be kept high. Thereby, since the temperature of the

heat exchangers

15a and 15b between heat media can be kept high, freezing of a heat medium, an antifreeze liquid, etc. can be suppressed.

(Defrost operation mode 2-4)
In the defrosting operation mode 2-2, the opening / closing device 17a has been described as being closed. However, the defrosting operation mode 2-4 in which the opening / closing device 17a is open may be performed. That is, the defrost operation mode 2-4 is a defrost operation mode that is shifted from the heating main operation mode, and the opening / closing device 17a is open. Here, the case where heating is required for the indoor unit 2a and the cooling is required for the indoor unit 2b will be described as an example.
When shifting from the heating main operation mode to the defrosting operation mode 2-4, the expansion device 16a is fully closed or the opening is set so that the refrigerant does not flow, and the heat exchanger 15a between the heat medium in which cold heat is generated for cooling is used. Thus, the expansion device 16b is opened, and the heat exchanger related to heat medium 15b in which the heat is generated for heating circulates the refrigerant. Moreover, about 2nd refrigerant | coolant flow path switching device 18a, 18b, both are switched to the heating side, and are connected with a high voltage | pressure piping.
The flow of the heat medium in the heat medium circuit B is the flow in the heating main operation mode, and is generated in the heat exchanger related to heat medium 15a in the heating main operation mode before the transition to the defrost operation mode 2-4. It is possible to continue the cooling operation and the heating operation of the indoor space 7 using the cold heat and the heat generated by the heat exchanger related to heat medium 15b.

Thus, even if the opening / closing device 17a is opened, the refrigerant that has flowed into the heat medium relay unit 3 and passed through the opening / closing device 17a merges with the refrigerant that flows out of the expansion device 16b. That is, in the defrost operation mode 2-4, the heat source side refrigerant flowing out from the expansion device 16a via the second refrigerant flow switching device 18a and the heat exchanger related to heat medium 15a, and the heat source side refrigerant flowing in from the opening / closing device 17a Join. Then, the merged refrigerant then flows out of the heat medium relay unit 3 through the opening / closing device 17b and the bypass refrigerant pipe 4c.
Here, when the opening / closing device 17a is opened, there is a heat source side refrigerant flowing into the bypass refrigerant pipe 4c via the opening / closing device 17a, so the second refrigerant flow switching device 18 and the heat exchanger related to heat medium 15 have The circulating amount of refrigerant flowing in is reduced, and the pressure loss of the heat source side refrigerant is reduced. And since the pressure loss of the heat source side refrigerant can be reduced, the refrigerant pressure in the heat exchanger related to heat medium 15b can be kept high. Thereby, since the temperature of the heat exchanger related to heat medium 15b can be kept high, freezing of the heat medium and the antifreeze liquid can be suppressed.

(Defrost operation mode 2-5)
In the defrost operation mode 2-2 and the defrost operation mode 2-4, the operation mode is such that the refrigerant is not supplied to the heat exchanger related to heat medium 15a, but the defrost that supplies the refrigerant to the heat exchanger related to heat medium 15a. Operation mode 2-5 may be implemented (see FIG. 9). The defrosting operation mode 2-5 is a defrosting operation mode for shifting from the heating main operation mode. In the defrost operation mode 2-5, the refrigerant is also supplied to the heat exchanger related to heat medium 15a, and the opening / closing device 17a is closed and the opening / closing device 17b is opened. In FIG. 9, a case where heating is required for the indoor units 2a to 2c and cooling is required for the indoor unit 2d will be described as an example.
The defrosting operation mode 2-5 is preferably performed when it is desired to improve both the cooling capacity of the indoor unit that is continuing the cooling operation and to shorten the defrosting time.

In the defrost operation mode 2-5, both the

expansion devices

16a and 16b are fully open or close to full open, and the heat exchanger 15a that has generated cold heat for cooling and hot heat is generated for heating. The refrigerant is circulated through both the heat exchanger related to heat medium 15b. Moreover, about 2nd refrigerant | coolant flow path switching device 18a, 18b, both are switched to the heating side, and are connected with a high voltage | pressure piping. The flow of the heat medium in the heat medium circuit B is the flow in the heating main operation mode, so that the cooling operation and the heating operation of the indoor space 7 are continued.

By flowing a supercooled liquid having a refrigerant temperature of about 0 ° C. or a two-phase refrigerant through the heat exchanger 15a between the heat medium, the heat medium between the heat medium circulating in the indoor unit 2d that continues the cooling operation in the defrost operation mode 2-5 The heat medium in the heat exchanger 15a is cooled by radiating heat to the refrigerant, and the cooling capacity is improved as compared with the case where the refrigerant does not flow through the heat exchanger related to heat medium 15a.
Furthermore, the refrigerant in the heat exchanger related to heat medium 15a absorbs heat from the heat medium, so that among the low-pressure two-phase refrigerant flowing out from the expansion device 16a, compared to the case where the refrigerant does not flow into the heat exchanger related to heat medium 15a. The ratio of the gas layer increases, the ratio of the low-temperature and low-pressure gas refrigerant sucked into the compressor 10 increases, and the heat capacity of the high-temperature and high-pressure gas refrigerant discharged from the compressor 10 increases. The defrosting operation time of the heat source side heat exchanger 12 can be shortened.

The refrigerant flowing into the heat exchanger related to

heat medium

15a, 15b via the second refrigerant flow switching devices 18a, 18b is a supercooled liquid substantially equal to the pressure of the heat source side refrigerant flowing into the heat medium converter 3, or two It is a phase refrigerant. The supercooled liquid or the two-phase refrigerant has a saturation temperature of about 0 ° C. or higher.
In addition, of the heat medium in the heat medium circuit B, the heat medium heated by the inter-heat medium heat exchanger 15b is heated to about 20 ° C. or more by the heating main operation mode before the defrost operation mode 2-5. It is warm. On the other hand, of the heat medium in the heat medium circuit B, the heat medium cooled by the inter-heat medium heat exchanger 15a is about 5 to 10 ° C. or higher. Thereby, the temperature of the refrigerant flowing into the heat exchangers between

heat mediums

15a and 15b becomes about 0 ° C. or higher, and the cooling of the heat medium to a low temperature of 0 ° C. or lower is suppressed. That is, the heat medium is prevented from freezing due to the refrigerant flowing into the

heat exchangers

15a and 15b.

Further, when it is desired to further prevent the heat medium in the heat exchanger related to heat medium 15a from freezing, the temperature of the heat medium flowing into the heat exchanger related to heat medium 15a is a predetermined temperature (for example, about 3 ° C.). When the temperature decreases below, the expansion device 16a is closed for the refrigerant circulation circuit A, and the circulation of the heat medium is preferably continued for the heat medium circulation circuit B.

When there is no request for heating operation or cooling operation of the indoor space 7 or when it is desired to shorten the defrosting time, the blower (not shown) installed in the indoor unit 2 is stopped and the defrosting operation mode 2- If the heat medium flow control device 25 corresponding to the indoor heat exchanger 26 installed in the indoor unit 2 or all the indoor units 2 that were operating before the transition to 5 is opened and the heat medium is circulated, Well, since the heat medium is circulated through the heat medium circuit B in this way, the heat medium does not radiate to the air from the use side heat exchanger 26, so that the defrost time can be further shortened.

[Refrigerant piping 4]
As described above, the air conditioning apparatus 100 has several operation modes. In these operation modes, the heat source side refrigerant flows through the refrigerant pipe 4 that connects the outdoor unit 1 and the heat medium relay unit 3.

[Piping 5]
In some operation modes executed by the air conditioner 100, a heat medium such as water or antifreeze flows through the pipe 5 connecting the heat medium converter 3 and the indoor unit 2.

[Heat source side refrigerant]
As the heat source side refrigerant, HFO1234yf, HFO1234ze, R32, HC, a mixed refrigerant containing R32 and HFO1234yf, or a refrigerant using a mixed refrigerant containing at least one component of the aforementioned refrigerant can be used as the heat source side refrigerant.
These refrigerants are all flammable refrigerants. If the plate heat exchanger is damaged due to freezing or the like, these refrigerants may flow into the heat medium. However, the air conditioner 100 is not easily damaged because the

heat exchangers

15a and 15b are not easily frozen. That is, even if a combustible refrigerant is employed, the possibility that the refrigerant leaks into the air-conditioning target space can be reduced.

[Heat medium]
As the heat medium, for example, brine (antifreeze), water, a mixed solution of brine and water, a mixed solution of water and an additive having a high anticorrosive effect, or the like can be used. Therefore, in the air conditioning apparatus 100, even if the heat medium leaks into the indoor space 7 through the indoor unit 2, it contributes to the improvement of safety because a highly safe heat medium is used. Become.

Further, in the cooling main operation mode and the heating main operation mode, when the state (heating or cooling) of the heat exchanger related to heat medium 15b and the heat exchanger related to heat medium 15a is changed, the water that has been used up to now is cooled down. As a result, cold water is heated to become hot water, resulting in wasted energy. Therefore, the air conditioner 100 is configured such that the heat exchanger related to heat medium 15b is always on the heating side and the heat exchanger related to heat medium 15a is on the cooling side in both the cooling main operation mode and the heating main operation mode. is doing.

Further, when the heating load and the cooling load are mixed in the use side heat exchanger 26, the first heat medium flow switching device corresponding to the use side heat exchanger 26 performing the heating operation. 22 and the second heat medium flow switching device 23 are switched to flow paths connected to the heat exchanger related to heat medium 15b for heating, and the first heat medium corresponding to the use side heat exchanger 26 performing the cooling operation By switching the flow path switching device 22 and the second heat medium flow path switching device 23 to a flow path connected to the heat exchanger related to heat medium 15a for cooling, in each indoor unit 2, heating operation and cooling operation are performed. It can be done freely.

Although the air conditioning apparatus 100 has been described as being capable of mixed cooling and heating operation, the present invention is not limited to this. For example, there is one heat exchanger 15 between the heat medium and one expansion device 16, and a plurality of use side heat exchangers 26 and heat medium flow control devices 25 are connected in parallel to either the cooling operation or the heating operation. Even in a configuration that can only be performed, the same effect can be obtained.

Moreover, it goes without saying that the same holds true even when only one use-side heat exchanger 26 and one heat medium flow control device 25 are connected. As the heat exchanger 15 between heat mediums 15 and the expansion device 16, Of course, there is no problem even if there are multiple things that move in the same way. Further, the case where the heat medium flow control device 25 is built in the heat medium converter 3 has been described as an example. However, the heat medium flow control device 25 is not limited thereto, and may be built in the indoor unit 2. 3 and the indoor unit 2 may be configured separately.

In general, the heat source side heat exchanger 12 and the use side heat exchanger 26 are provided with a blower, and in many cases, condensation or evaporation is promoted by blowing air, but this is not restrictive. For example, the use side heat exchanger 26 may be a panel heater using radiation, and the heat source side heat exchanger 12 is of a water-cooled type that moves heat by water or antifreeze. Can also be used. That is, the heat source side heat exchanger 12 and the use side heat exchanger 26 can be used regardless of the type as long as they have a structure capable of radiating heat or absorbing heat.

1 outdoor unit, 2 indoor unit, 2a to 2d indoor unit, 3 heat medium converter, 4 refrigerant piping, 4a first connection piping, 4b second connection piping, 4c bypass refrigerant piping, 5 piping, 6 outdoor space, 7 indoors Space, 8 space, 9 building, 10 compressor, 11 first refrigerant flow switching device, 12 heat source side heat exchanger, 13a-13d check valve, 15 heat exchanger between heat medium, 15a, 15b heat between heat medium Exchanger, 16 throttle device, 16a, 16b throttle device, 17 switchgear, 17a, 17b switchgear, 18a, 18b second refrigerant flow switching device, 19 accumulator, 21a, 21b pump, 22 first heat medium flow channel Switching device, 22a to 22d, first heat medium flow switching device, 23, second heat medium flow switching device, 23a to 23d, second heat medium flow switching device, 25 heat medium Flow rate adjustment device, 25a to 25d Heat medium flow rate adjustment device, 26 User side heat exchanger, 26a to 26d User side heat exchanger, 31a, 31b First temperature sensor, 34 Second temperature sensor, 34a to 34d Second temperature sensor , 35 3rd temperature sensor, 35a-35d 3rd temperature sensor, 36 pressure sensor, 36a, 36b pressure sensor, 40a 1st outdoor temperature sensor, 40b 2nd outdoor temperature sensor, 70 control device, 100 air conditioner, A refrigerant Circulation circuit, B Heat medium circulation circuit.

Claims

An outdoor unit equipped with a compressor, a first refrigerant flow switching device, and a heat source side heat exchanger;
A heat exchanger including a heat exchanger between heat media, a throttle device, a second refrigerant flow switching device, and a pump;
And at least one indoor unit equipped with a use side heat exchanger,
Connecting the compressor, the first refrigerant flow switching device, the throttle device, the second refrigerant flow switching device, and the heat exchanger related to heat medium with a refrigerant pipe to constitute a refrigeration cycle circuit;
Connecting the heat exchanger between heat medium and the heat exchanger on the use side with a heat medium pipe to constitute a heat medium circulation circuit in which a heat medium different from the refrigerant circulates;
In the air conditioner that executes the defrost operation mode of switching the first refrigerant flow switching device and supplying the refrigerant discharged from the compressor to the heat source side heat exchanger,
In the defrost operation mode,
The refrigerant flowing out of the heat source side heat exchanger is
A part thereof is supplied to the heat exchanger related to heat medium without going through the expansion device,
The remainder is returned to the outdoor unit without passing through the expansion device and the heat exchanger related to heat medium.
In the defrost operation mode,
The air conditioner according to claim 1, wherein the pump is driven to circulate the heat medium in the heat medium circulation circuit.
A pipe through which the refrigerant flowing from the outdoor unit into the heat medium relay machine is a first refrigerant pipe,
When the pipe for flowing the refrigerant flowing into the outdoor unit from the heat medium converter is the second refrigerant pipe,
One end is connected to the first refrigerant pipe, the other end is connected to the second refrigerant pipe, and the bypass pipe bypassing the heat exchanger related to heat medium and the expansion device;
Refrigerant that is provided in the first refrigerant pipe, is located closer to the outdoor unit than a connection point between the first refrigerant pipe and the bypass pipe, and flows into the heat exchanger related to heat medium from the first refrigerant pipe A first opening / closing device for adjusting the flow of
The air conditioner according to claim 1, further comprising: a second opening / closing device that is provided in the bypass pipe and adjusts a flow of the refrigerant bypassed from the bypass pipe.
(Defrost operation mode 1)
Close the expansion device, open the first opening and closing device and the second opening and closing device,
Returning the refrigerant that has flowed out of the heat source side heat exchanger to the outdoor unit via the first refrigerant pipe, the first switchgear, the bypass pipe, the second switchgear, and the second refrigerant pipe. The air conditioner according to claim 3.
(Defrost operation mode 2-1, 2-2)
Open the throttle device, close the first opening and closing device, open the second opening and closing device,
Refrigerant flowing out from the heat source side heat exchanger, the first refrigerant pipe, the second refrigerant flow switching device, the heat exchanger between heat medium, the expansion device, the bypass pipe, the second opening and closing device, The air conditioner according to claim 3, which is dependent on claim 2, wherein the air conditioner is returned to the outdoor unit via the second refrigerant pipe.
(Defrost operation mode 2-3, 2-4)
Open the throttle device, the first opening / closing device and the second opening / closing device,
Part of the refrigerant flowing out of the heat source side heat exchanger flows into the bypass pipe through the first refrigerant pipe, the second refrigerant flow switching device, the heat exchanger related to heat medium, and the expansion device. Let
The remaining refrigerant flowing out of the heat source side heat exchanger is caused to flow into the bypass pipe via the first refrigerant pipe and the first opening / closing device,
The subordinate to claim 2, wherein a part of the refrigerant flowing into the bypass pipe and the remainder of the refrigerant are returned to the outdoor unit via the second opening / closing device and the second refrigerant pipe. Item 4. The air conditioner according to Item 3.
(Defrost operation mode 2-5)
At the time of transition from the heating main operation mode to the defrost operation mode,
Open the throttle device, close the first opening and closing device, open the second opening and closing device,
Refrigerant flowing out from the heat source side heat exchanger, the first refrigerant pipe, the second refrigerant flow switching device, the heat exchanger between heat medium, the expansion device, the bypass pipe, the second opening and closing device, Return to the outdoor unit via the second refrigerant pipe,
A heat medium is supplied from the inter-heat medium heat exchanger functioning as an evaporator in the heating main operation mode to the use side heat exchanger corresponding to the indoor unit that performs the cooling operation. The air conditioning apparatus according to claim 3, which is dependent on claim 2.
The second refrigerant flow switching device includes:
The air conditioner according to any one of claims 1 to 7, wherein the air conditioner is configured by at least one of a four-way valve, a three-way valve, a two-way valve, and a solenoid valve.
As the heat source side refrigerant,
The air conditioning according to any one of claims 1 to 8, wherein HFO1234yf, HFO1234ze, R32, HC, a mixed refrigerant of R32 and HFO1234yf, or a mixed refrigerant including at least one of these refrigerants is employed. apparatus.