VENTILATION APPARATUS AND VENTILATION METHOD

A ventilation apparatus includes a compressor; a first heat exchanger configured to function as a condenser or an evaporator; a first air flow path configured to supply air taken in from outdoors to an indoor space after passing through the first heat exchanger; a second heat exchanger configured to function as a condenser or an evaporator; a second air flow path configured to exhaust air taken in from the indoor space to the outdoors after passing through the second heat exchanger; a refrigerant circuit through which a refrigerant flows, the refrigerant circuit being connected to the compressor, the first heat exchanger, and the second heat exchanger by a refrigerant pipe; and a control unit configured to guide a flow of air in the indoor space to the second heat exchanger when the second heat exchanger is determined to be in a frosted state, to increase a temperature of the second heat exchanger, and configured to output a predetermined instruction to an actuator configured to control a state of the refrigerant in the refrigerant circuit to increase a temperature of the refrigerant flowing into the second heat exchanger.

TECHNICAL FIELD

The present disclosure relates to a ventilation apparatus and a ventilation method.

BACKGROUND ART

Conventionally, a ventilation air conditioning apparatus is known in which indoor ventilation is performed by an exhaust fan and an air supply fan, outside air that is heat exchanged with a refrigerant by a first heat exchanger is blown indoors, and indoor air that is heat exchanged with refrigerant by a second heat exchanger is discharged outdoors (see Patent Document 1). In the ventilation air conditioning apparatus described in Patent Document 1, when defrosting is performed, a technology for defrosting by switching the flow of refrigerant between the first heat exchanger and the second heat exchanger, is proposed. When the defrosting is performed, the heating operation is temporarily stopped.

CITATION LIST

Patent Document

SUMMARY OF INVENTION

Technical Problem

In the ventilation air conditioning apparatus described in Patent Document 1, when the ventilation air conditioning apparatus is temporarily stopped for defrosting, defrosting can be performed by radiating heat from the second heat exchanger by switching the operation, but it may take time.

The purpose of the present disclosure is to efficiently perform defrosting.

Solution to Problem

The present disclosure provides a ventilation apparatus including:a compressor;a first heat exchanger configured to function as a condenser or an evaporator;a first air flow path configured to supply air taken in from outdoors to an indoor space after passing through the first heat exchanger;a second heat exchanger configured to function as a condenser or an evaporator;a second air flow path configured to exhaust air taken in from the indoor space to the outdoors after passing through the second heat exchanger;a refrigerant circuit through which a refrigerant flows, the refrigerant circuit being connected to the compressor, the first heat exchanger, and the second heat exchanger by a refrigerant pipe; anda control unit configured to guide a flow of air in the indoor space to the second heat exchanger when the second heat exchanger is determined to be in a frosted state, to increase a temperature of the second heat exchanger, and configured to output a predetermined instruction to an actuator configured to control a state of the refrigerant in the refrigerant circuit to increase a temperature of the refrigerant flowing into the second heat exchanger.

The ventilation apparatus improves the defrosting efficiency of a second heat exchanger by controlling the state of the refrigerant in the refrigerant circuit so as to increase the temperature of the refrigerant flowing into the second heat exchanger while guiding the flow of air in an indoor space to the second heat exchanger.

In the above ventilation apparatus, the control unit outputs the predetermined instruction indicating to stop the compressor, when the second heat exchanger is determined to be in the frosted state.

According to the ventilation apparatus, the temperature of the refrigerant in the second heat exchanger can be increased by stopping the compressor, thereby improving the defrosting efficiency of the second heat exchanger.

In the above ventilation apparatus,a plurality of the second heat exchangers are provided,the refrigerant circuit further includes a first valve part configured to adjust an opening degree of a flow path connected to the second heat exchanger, for each of the second heat exchangers, andwhen a predetermined second heat exchanger included among the plurality of the second heat exchangers is determined to be in the frosted state, the control unit outputs the predetermined instruction for closing the first valve part corresponding to the predetermined second heat exchanger.

According to the ventilation apparatus, the temperature of the refrigerant in the predetermined second heat exchanger can be increased by closing the first valve part, thereby improving the defrosting efficiency of the second heat exchanger.

According to the ventilation apparatus, the temperature of the refrigerant in the predetermined second heat exchanger corresponding to the first valve part can be increased by closing the first valve part, thereby improving the defrosting efficiency of the second heat exchanger.

In the above ventilation apparatus, when the plurality of the second heat exchangers are determined to be in the frosted state, the control unit outputs the predetermined instruction for closing, in a predetermined order, a plurality of the first valve parts corresponding to the plurality of the second heat exchangers determined to be in the frosted state.

According to the ventilation apparatus, by closing the first valve part in a predetermined order, the second heat exchangers are prevented from defrosting simultaneously, and the reduction of comfort can be prevented.

In the above ventilation apparatus,the refrigerant circuit includes a second valve part configured to adjust an opening degree of a flow path, the second valve part being provided between the first heat exchanger and the second heat exchanger, andwhen the second heat exchanger is determined to be in the frosted state while the second heat exchanger is functioning as an evaporator, the control unit outputs the predetermined instruction for increasing the opening degree adjusted by the second valve part as compared with before the second heat exchanger is determined to be in the frosted state.

According to the ventilation apparatus, by increasing the opening degree of the second valve part and closing the first valve part in a predetermined order, the second heat exchangers are prevented from defrosting simultaneously and the reduction of comfort can be prevented.

The above ventilation apparatus further includes:a third valve part provided downstream from the second valve part in a flow of the refrigerant in the refrigerant circuit while the second valve part is functioning as an evaporator, andwhen the second heat exchanger is determined to be in the frosted state while the second heat exchanger is functioning as an evaporator, the control unit further outputs the predetermined instruction for decreasing the opening degree adjusted by the third valve part as compared with before the second heat exchanger is determined to be in the frosted state.

According to the ventilation system, by reducing the opening degree of the third valve part, the temperature of the refrigerant flowing through the second heat exchanger upstream is increased to improve the defrosting efficiency of the second heat exchanger.

In the above ventilation apparatus, the refrigerant circuit includes a bypass pipe configured to pass the refrigerant to the second heat exchanger from the compressor without involving the first heat exchanger, while the second heat exchanger is functioning as an evaporator, andwhen the second heat exchanger is determined to be in the frosted state, the control unit outputs the predetermined instruction for causing the refrigerant compressed at the compressor to flow to the second heat exchanger via the bypass pipe.

According to the ventilation apparatus, by passing the refrigerant through the bypass pipe to the second heat exchanger, the temperature of the refrigerant flowing through the second heat exchanger is raised to improve the defrosting efficiency of the second heat exchanger.

In the above ventilation apparatus, to guide the flow of the air in the indoor space to the second heat exchanger, the control unit controls a first guide mechanism configured to switch between either guiding or not guiding air to the second heat exchanger from a ceiling space adjacent to and above the indoor space, or controls a second guide mechanism configured to switch between either guiding or not guiding air to the second heat exchanger from the indoor space.

According to the ventilation apparatus, by passing warm air to the second heat exchanger, the temperature of the refrigerant flowing through the second heat exchanger is increased to improve the defrosting efficiency of the second heat exchanger.

The above ventilation apparatus further includes:a bypass guide mechanism configured guide air that has undergone heat exchange by the first heat exchanger to the second heat exchanger, andwhen the second heat exchanger is determined to be in the frosted state and the air that has undergone heat exchange by the first heat exchanger is determined to have a temperature higher than a predetermined temperature, the control unit controls the bypass guide mechanism to guide the air that has undergone heat exchange to the second heat exchanger.

According to the ventilation apparatus, the temperature of the refrigerant flowing through the second heat exchanger is increased by passing warm air to the second heat exchanger through the bypass guide mechanism to improve the defrosting efficiency of the second heat exchanger.

In the above ventilation apparatus,a plurality of the second heat exchangers are provided,the second air flow path through which air taken in from the indoor space is exhausted to the outdoors is provided for each of the second heat exchangers, andthe control unit adjusts an air volume of air flowing through the second air flow path corresponding to the second heat exchanger based on a status of each of the plurality of the second heat exchangers.

According to the ventilation apparatus, by adjusting the air volume of air flowing in accordance with the status of each of the plurality of the second heat exchangers, it is possible to prevent the simultaneous defrosting of the second heat exchangers and to prevent the reduction of comfort.

In the above ventilation apparatus, when a degree of frosting of one of the plurality of the second heat exchangers is greater than a degree of frosting of another one of the plurality of the second heat exchangers, the control unit implements control such that a first air volume of the second air flow path corresponding to the one of the plurality of the second heat exchangers is increased as compared with a second air volume of the second air flow path corresponding to the other one of the plurality of the second heat exchangers.

According to the ventilation apparatus, the reduction in comfort can be prevented by defrosting the second heat exchanger according to the degree of frosting of the second heat exchanger.

In the above ventilation apparatus, when implementing control to increase the first air volume, the control unit implements control to decrease the second air volume as compared with before increasing the first air volume.

According to the ventilation apparatus, comfort can be maintained by preventing negative pressure in the indoor space.

In the above ventilation apparatus, the control unit outputs a signal to increase a temperature set with respect to an air conditioner provided in the indoor space, when the second heat exchanger is determined to be in the frosted state.

According to the ventilation apparatus, by raising the temperature set in the air conditioner, the temperature of the refrigerant flowing in the second heat exchanger is raised to improve the defrosting efficiency of the second heat exchanger.

The above ventilation apparatus further includes:a switching mechanism configured to switch between whether to supply air from the indoor space or to supply air from the outdoors as air flowing through the second air flow path, andthe control unit controls the switching mechanism to supply air starting from air having a higher detected temperature between the air from the indoor space and the air from the outdoors.

According to the ventilation apparatus, by supplying air starting from air having a higher detected temperature to pass warm air to the second heat exchanger, the temperature of the refrigerant flowing through the second heat exchanger is raised to improve the defrosting efficiency of the second heat exchanger.

In the above ventilation apparatus, when the second heat exchanger is determined to be in the frosted state after receiving, from an air conditioner, a signal indicating that a defrosting operation is to be performed, the control unit prevents output of the predetermined instruction to the actuator configured to control the state of the refrigerant in the refrigerant circuit.

According to the ventilation apparatus, by preventing defrosting of the second heat exchanger, simultaneous defrosting of the air conditioner and the ventilation apparatus can be prevented to prevent the reduction in comfort.

In the above ventilation apparatus, when the signal indicating that the defrosting operation is to be performed is received from the air conditioner, the control unit further implements control to increase an air volume supplied to the indoor space from the first air flow path as compared with the air volume before receiving the signal indicating that the defrosting operation is to be performed from the air conditioner, and implements control to increase the air volume exhausted from the second air flow path to the outdoors as compared with the air volume before receiving the signal indicating that the defrosting operation is to be performed from the air conditioner.

According to the ventilation apparatus, by increasing the air volume, instead of the air conditioner, the heating capability of the ventilation apparatus can be improved and comfort can be maintained.

In the above ventilation apparatus, when the second heat exchanger is determined to be in the frosted state, the control unit further transmits, to an air conditioner, a signal indicating not to perform a defrosting operation.

According to the ventilation apparatus, by preventing defrosting of the air conditioner, simultaneous defrosting of the air conditioner and the ventilation apparatus can be prevented to prevent the reduction in comfort.

The present disclosure provides a ventilation apparatus including:a compressor;a first heat exchanger configured to function as a condenser or an evaporator;a first air flow path indicating a flow path allowing to exhaust air taken in from outdoors to an indoor space after passing through the first heat exchanger;a second heat exchanger configured to function as a condenser or an evaporator;a second air flow path indicating a flow path allowing to exhaust air taken in from the indoor space to the outdoors after passing through the second heat exchanger;a refrigerant circuit through which a refrigerant flows, the refrigerant circuit being connected to the compressor, the first heat exchanger, and the second heat exchanger by a refrigerant pipe; anda control unit configured to output a predetermined instruction to cause the second heat exchanger to function as a condenser and to cause the first heat exchanger to function as an evaporator, to an actuator configured to control a state of the refrigerant in the refrigerant circuit to increase a temperature of the refrigerant flowing into the second heat exchanger, when the second heat exchanger is determined to be in a frosted state while the second heat exchanger is functioning as an evaporator.

According to the ventilation apparatus, the defrosting efficiency of the second heat exchanger is improved by making the second heat exchanger function as a condenser.

In the above ventilation apparatus, when the second heat exchanger is determined to be in the frosted state while the second heat exchanger is functioning as an evaporator, the control unit outputs the predetermined instruction and switches a flow of air in the first air flow path to be exhausted to the outdoors from the indoor space.

According to the ventilation apparatus, by switching the air flow in the first air flow path so as to exhaust the air to the outdoors, the temperature of the refrigerant flowing in the refrigerant circuit rises, thereby improving the defrosting efficiency of the second heat exchanger.

In the above ventilation apparatus, when the second heat exchanger is determined to be in the frosted state while the second heat exchanger is functioning as an evaporator, the control unit further switches a flow of air in the second air flow path to be supplied to the indoor space from the outdoors.

According to the ventilation apparatus, by supplying air from the outdoors to the indoor space, it is possible to prevent reduction in comfort by preventing negative pressure in the indoor space.

The above ventilation apparatus further includes:a first casing configured to house the first heat exchanger and at least a part of the first air flow path; anda second casing configured to house the second heat exchanger and at least a part of the second air flow path, whereinthe first casing and the second casing are separable.

According to the ventilation apparatus, the first casing and the second casing are separable, and, therefore, the arrangement layout can be facilitated, and the burden in installation can be reduced.

The present disclosure provides ventilation method using a plurality of ventilation apparatuses provided in a predetermined space, each of the ventilation apparatuses including:a compressor;a first heat exchanger configured to function as a condenser or an evaporator;a first air flow path configured to supply air taken in from outdoors to an indoor space after passing through the first heat exchanger;a second heat exchanger configured to function as a condenser or an evaporator;a second air flow path configured to exhaust air taken in from the indoor space to the outdoors after passing through the second heat exchanger; anda refrigerant circuit through which a refrigerant flows, the refrigerant circuit being connected to the compressor, the first heat exchanger, and the second heat exchanger by a refrigerant pipe, whereina control unit executes:acquiring a frosted state of the plurality of the second heat exchangers;generating a plurality of patterns for performing a defrosting operation for the plurality of the second heat exchangers when the plurality of the second heat exchangers are determined to be in the frosted state while the plurality of the second heat exchangers are functioning as an evaporator; andacquiring a status of the predetermined space and implementing control to defrost the second heat exchanger by using one of the generated plurality of patterns based on the frosted state and the status of the predetermined space.

According to the ventilation method, defrosting control can be performed in an appropriate pattern, thereby improving defrosting the efficiency of the second heat exchanger.

The present disclosure provides a ventilation method performed by a control unit that controls a ventilation apparatus, the ventilation apparatus including:a compressor;a first heat exchanger configured to function as a condenser or an evaporator;a first air flow path configured to supply air taken in from outdoors to an indoor space after passing through the first heat exchanger;a second heat exchanger configured to function as a condenser or an evaporator;a second air flow path configured to exhaust air taken in from the indoor space to the outdoors after passing through the second heat exchanger; anda refrigerant circuit through which a refrigerant flows, the refrigerant circuit being connected to the compressor, the first heat exchanger, and the second heat exchanger by a refrigerant pipe, whereinthe control unit executes:guiding a flow of air in the indoor space to the second heat exchanger when the second heat exchanger is determined to be in a frosted state to increase a temperature of the second heat exchanger; andoutputting a predetermined instruction to an actuator configured to control a state of the refrigerant in the refrigerant circuit to increase a temperature of the refrigerant flowing into the second heat exchanger.

According to the ventilation method, the defrosting efficiency of the second heat exchanger is improved by controlling the state of the refrigerant in the refrigerant circuit so as to guide the air flow in the indoor space to the second heat exchanger and raise the temperature of the refrigerant flowing into the second heat exchanger.

DESCRIPTION OF EMBODIMENTS

Hereinafter, the present embodiment will be described with reference to the drawings. Note that the following embodiments are essentially preferred examples and the embodiments are not intended to limit the scope of the present disclosure, the application, or the use thereof.

First Embodiment

FIG.1is a diagram illustrating a configuration example of a ventilation apparatus and an air conditioner according to the first embodiment. In the example illustrated inFIG.1, a ventilation apparatus1and an air conditioner2are provided for air conditioning an indoor space.

In the present embodiment, as an example of an indoor space, an example including a living room space R11and a ceiling space R12will be described. However, the indoor space is not limited to the living room space R11and the ceiling space R12, and may be a space inside a building, for example, a space under the floor.

The living room space R11is, for example, a living room inside an office or a house. The ceiling space R12is an adjacent space above the living room space R11. The ceiling space R12exists above the living room space R11, and, therefore, warm air tends to be collected in the ceiling space R12.

The air conditioner2includes an outdoor unit70and two air-conditioning indoor units81and82. In the present embodiment, the number of air-conditioning indoor units is not limited to two units, but may be one unit or three units or more.

The air conditioner2performs a vapor compression type refrigeration cycle to cool and heat the living room space R11. The air conditioner2according to the present embodiment can both cool and heat the living room space R11. However, the present embodiment is not limited to an air conditioner capable of both cooling and heating, and may be a device capable of only cooling, for example.

The space between the outdoor unit70and the two air-conditioning indoor units81and82is connected by a connection pipe F5. The connection pipe F5includes a liquid refrigerant connection pipe and a gas refrigerant connection pipe (not illustrated). Accordingly, a refrigerant circuit in which a refrigerant circulates between the outdoor unit70and the two air-conditioning indoor units81and82is formed. When refrigerant circulates in the refrigerant circuit, a vapor compression type refrigeration cycle is performed in the air conditioner2.

The outdoor unit70is arranged outdoors. The outdoor unit70is provided with a heat exchanger, and the air in which the heat is exchanged with the refrigerant flowing through the heat exchanger is discharged outdoors.

The air-conditioning indoor units81and82are provided with a heat exchanger, and the air-conditioning indoor units81and82exchange the heat in the air with the refrigerant flowing through the heat exchanger, and blow the heat exchanged air into the living room space R11. In the present embodiment, the air-conditioning indoor units81and82are ceiling-installed types installed on the ceiling of the living room space R11. In particular, the air-conditioning indoor units81and82of the present embodiment are ceiling-embedded type air-conditioning indoor units, and air in which heat has been exchanged is blown out from ventilation ports93A and93B. Although an example in which the ventilation ports93A and93B are provided on the ceiling will be described in the present embodiment, the positions at which the ventilation ports93A and93B are provided are not particularly limited. The air-conditioning indoor units81and82are not limited to the ceiling-embedded type, and may be a ceiling-suspended type. The air-conditioning indoor units81and82may be other than the ceiling installed type, such as a wall mounted type or a floor mounted type.

The ventilation apparatus1includes the exhaust unit10, the air supply unit20, a compressor unit50, refrigerant circuits F1, F2, F3, and F4, an air supply flow path P1, and a return air flow path P2.

The ventilation apparatus1supplies the air taken in from outdoors to the living room space R11and exhausts the air taken in from the indoor space (including the living room space R11) to the outdoors. Thus, the ventilation apparatus1implements the replacement of the air in the living room space R11.

Further, the ventilation apparatus1according to the present embodiment exchanges heat between the exhaust unit10and the air supply unit20to reduce the temperature difference between the temperature of the air taken in from the outdoors and the temperature of the living room space R11.

The air supply flow path P1(an example of the first air flow path) is a flow path for supplying air taken in from the outdoors (outside air) to the living room space R11from the ventilation port92after passing through the air supply unit20including the first heat exchanger22. Although the present embodiment will describe an example in which the ventilation port92is provided on the ceiling, the position at which the ventilation port92is provided is not particularly limited.

The return air flow path P2(an example of the second air flow path) is a flow path for exhausting air (return air) taken in from the ventilation port91of the living room space R11to the outdoors after passing through the exhaust unit10including the second heat exchanger12. Although the present embodiment will describe an example in which the ventilation port91is provided on the ceiling, the position at which the ventilation port91is provided is not particularly limited.

The refrigerant circuits F1, F2, F3, and F4are circuits in which the compressor unit50, the first heat exchanger22of the air supply unit20, and the second heat exchanger12of the exhaust unit10are connected by refrigerant pipe, and the refrigerant flows in these refrigerant circuits.

The control unit52of the compressor unit50, the control unit23of the air supply unit20, and the control unit13of the exhaust unit10are connected by a signal line S1indicated by a dotted line inFIG.1. Thus, information can be transmitted and received between the control unit52of the compressor unit50, the control unit23of the air supply unit20, and the control unit13of the exhaust unit10.

The compressor unit50is provided with a driving motor51and a control unit52, and controls circulation of the refrigerant in the refrigerant circuits F1, F2, F3, and F4by compressing any one of the refrigerants in the refrigerant circuits F1, F2, F3, and F4. For example, when the second heat exchanger12in the exhaust unit10functions as an evaporator, the compressor unit50compresses the refrigerant in the refrigerant circuit F2to circulate the refrigerant in the refrigerant circuits F1, F2, F3, and F4.

The driving motor51is a motor for rotating (driving) the compressor for compressing the refrigerant.

The control unit52controls the configuration in the compressor unit50. For example, the control unit52outputs an instruction for rotating (driving) the compressor to the driving motor51.

The air supply unit20includes a fan21, a first heat exchanger22, a control unit23, and a temperature detecting unit24, and takes in the outside air (OA), and supplies air (SA) to the living room space R11.

The fan21functions to supply air (SA) to the living room space R11from the outside air (OA) that is taken in.

The first heat exchanger22functions as a condenser or an evaporator.

The temperature detecting unit24detects the outdoor temperature, the surface temperature of the first heat exchanger22and the temperature of the refrigerant flowing through the first heat exchanger22.

The control unit23controls the configuration inside the air supply unit20. The control unit23performs various kinds of control according to the detection result by a temperature detecting unit14. For example, the control unit23adjusts the function of the first heat exchanger22as a condenser or an evaporator according to the detection result obtained by the temperature detecting unit24.

The exhaust unit10is provided with a fan11, a second heat exchanger12, a control unit13, and a temperature detecting unit14, takes in return air (RA) of the living room space R11, and exhausts (EA) the taken in air to the outdoors.

The fan11functions to exhaust (EA) the return air (RA) taken in from the living room space R11to the outdoors.

The second heat exchanger12functions as a condenser or an evaporator.

The temperature detecting unit14detects the outside air temperature, the surface temperature of the second heat exchanger12, and the temperature of the refrigerant flowing through the second heat exchanger12. Further, the temperature detecting unit14may detect the temperature of air in the living room space R11and the temperature of air in the ceiling space R12through the sensor unit (not illustrated).

The control unit13controls the configuration of the inside of the exhaust unit10. The control unit13performs various kinds of control according to the detection result obtained by the temperature detecting unit14. For example, the control unit13adjusts the function of the second heat exchanger12as a condenser or an evaporator according to the detection result of the temperature detecting unit14.

A process performed by the ventilation apparatus1when the air temperature is low will be described. When the air temperature is low, the ventilation apparatus1warms the outside air (OA) taken in from the outdoors in the air supply unit20, then supplies the air (SA) to the living room space R11, and cools the return air (RA) taken in from the living room space R11in the exhaust unit10, then exhausts the air (EA) to the outdoors. That is, the first heat exchanger22in the air supply unit20functions as a condenser, and the second heat exchanger12in the exhaust unit10functions as an evaporator. As the second heat exchanger12functions as an evaporator, the temperature of the refrigerant flowing through the second heat exchanger12becomes low, and therefore there is a possibility that the second heat exchanger12frosts. Therefore, in the present embodiment, when it is determined that frosting has occurred in the second heat exchanger12, a defrosting operation is performed.

Specifically, while the second heat exchanger12functions as an evaporator, the control unit13of the exhaust unit10determines whether a predetermined reference indicating a frosted state of the second heat exchanger12is satisfied from the detection result obtained by the temperature detecting unit14. As a predetermined reference indicating a frosted state of the second heat exchanger12, a state in which the temperature of the refrigerant passing through the second heat exchanger12remains below a predetermined value (e.g., 0 degrees) for a predetermined period of time (e.g., 10 minutes) may be considered. The present embodiment is not limited to the case where the temperature of the refrigerant is used to determine the frosted state, and the pressure of the refrigerant may be used to detect the frosted state. Other determination methods for determining the frosted state may be used. For example, the control unit13may detect that the surface temperature of the second heat exchanger12remains below a predetermined value (e.g., 0 degrees) for a certain period of time (e.g., 10 minutes). As another example, the control unit13may capture an image of the surface of the second heat exchanger12by an imaging apparatus, and make the determination based on how much the captured image data and the image data in regular state match each other. If it is possible to determine whether the second heat exchanger12is frosted, a method other than the above method may be used.

The control unit13of the exhaust unit10according to the present embodiment performs control for defrosting the second heat exchanger12when it is determined that the predetermined reference is satisfied. As control for defrosting, the control unit13controls to raise the temperature of the second heat exchanger12by guiding the air flow in the living room space R11to the second heat exchanger12. As a specific control, the rotation of the fan11of the exhaust unit10is maintained. As a result, the warm air in the living room space R11can flow to the second heat exchanger12.

Further, the control unit13of the exhaust unit10outputs an instruction (an example of a predetermined instruction) to stop the compressor in the compressor unit50to the driving motor51(an example of an actuator) of the compressor unit50through the control unit52of the compressor unit50.

The driving motor51of the present embodiment stops the circulation of the refrigerant in the refrigerant circuits F1, F2, F3, and F4by stopping the compressor based on the instruction.

As an example of the control for defrosting the second heat exchanger12, the control unit13of the present embodiment stops the circulation of the refrigerant in the refrigerant circuits F1, F2, F3, and F4, and passes warm air in the living room space R11to the second heat exchanger12to raise the temperature of the refrigerant flowing in the second heat exchanger to perform the defrosting.

In the defrosting of the conventional second heat exchanger, when the temperature of the outside air is low, the defrosting operation tends to be performed after the circulation of the refrigerant circuit is reversed. In the defrosting operation switched to the reverse cycle, the air supply to the indoor space is on the evaporator side, and, therefore, the temperature of the air supply is low, so it has been common to stop the air supply. In this case, the ventilation is insufficient. Further, in order to secure the air supply, it has been necessary to heat the air supply flow path with an auxiliary heater, etc., but the heat efficiency of the heating has been low.

Therefore, in the present embodiment, by stopping the circulation of the refrigerant circuits F1, F2, F3, and F4and using warm air (heat) in the living room space R11for defrosting the second heat exchanger12, it is possible to perform defrosting with high heat efficiency.

Second Embodiment

In the above-described embodiment, an example in which one exhaust unit is provided has been described. However, the number of exhaust units to be defrosted is not limited to one, and a plurality of exhaust units may be provided. Therefore, in the second embodiment, a configuration in which a plurality of exhaust units are provided and each of the exhaust units can be defrosted will be described.

FIG.2is a diagram illustrating an example of a configuration of a ventilation apparatus, an air conditioner, and an upper level control device according to the second embodiment. In the present embodiment, the upper level control device provided in an upper level of the air conditioner and the ventilation apparatus performs control. Note that that the same reference numerals are assigned to the same configuration as in the above embodiment, and descriptions thereof will be omitted.

In the example illustrated inFIG.2, an upper level control device100is provided for linking the ventilation apparatus1B and the air conditioner2B.

The air conditioner2B includes an outdoor unit170and two air-conditioning indoor units81and82. In the present embodiment, the number of air-conditioning indoor units is not limited to 2 units, but may be 1 unit or 3 units or more.

The outdoor unit170includes a control unit171together with a heat exchanger (not illustrated).

The control unit171controls the entire air conditioner2B. The control unit171also transmits and receives information to and from the upper level control device100. The control unit171performs various kinds of control in response to a control signal from the upper level control device100.

The ventilation apparatus1B includes a first exhaust unit110A, a second exhaust unit110B, a first air supply unit120A, a second air supply unit120B, a compressor unit150, refrigerant circuits F101, F102, F103, the F104, a first air supply flow path P101, a second air supply flow path P102, a first exhaust flow path P103, and a second exhaust flow path P104.

The first air supply flow path P101supplies air taken in from the outdoors through the first air supply unit120A including the first heat exchanger22to the living room space R11from the ventilation port92A.

The second air supply flow path P102supplies air taken in from the outdoors through the second air supply unit120B including the first heat exchanger22to the living room space R11from the ventilation port92B.

The first exhaust flow path P103exhausts air (return air) taken in from the ventilation port91A of the indoor space to the outdoors upon passing the air through the first exhaust unit110A including the second heat exchanger12.

The second exhaust flow path P104exhausts air (return air) taken in from the ventilation port91B of the indoor space to the outdoors upon passing the air through the second exhaust unit110B including the second heat exchanger12.

The refrigerant circuits F101, F102, F103, the F104are circuits that connect the compressor unit150, the first heat exchanger22of the first air supply unit120A and the second air supply unit120B, and the second heat exchanger12of the first exhaust unit110A and the second exhaust unit110B by a refrigerant pipe to allow the refrigerant to flow therein.

The control unit152of the compressor unit150, the control unit123of the first air supply unit120A, the control unit123of the second air supply unit120B, the control unit113A of the first exhaust unit110A, and the control unit113B of the second exhaust unit110B are connected by a signal line S101indicated by a dotted line. Thus, information can be transmitted and received between the control unit152, the two control units123, the control unit113A, and the control unit113B.

The control unit152of the compressor unit150transmits the status of the ventilation apparatus1B received from the two control units123, the control unit113A, and the control unit113B to the upper level control device100. As a result, the upper level control device100can implement control according to the status of the ventilation apparatus1B.

The first air supply unit120A is provided with a fan21, a first heat exchanger22, a control unit123, and a temperature detecting unit24, takes in outside air (OA), and supplies air (SA) from the ventilation port92A to the living room space R11.

The second air supply unit120B is provided with a fan21, a first heat exchanger22, a control unit123, and a temperature detecting unit24, takes in outside air (OA), and supplies air (SA) from the ventilation port92B to the living room space R11.

The control unit123controls the configuration in each air supply unit. Further, the control unit123transmits the detection result obtained by the temperature detecting unit24or the like in each air supply unit to the control unit152of the compressor unit150. The control unit152of the compressor unit150recognizes the current status from the detection result and transmits the recognition result to the upper level control device100. Thus, the upper level control device100can recognize the status of the first air supply unit120A and the second air supply unit120B.

The first exhaust unit110A is equipped with a fan11, a second heat exchanger12, a control unit113A, and a temperature detecting unit14, and takes in return air (RA) from the ventilation port91A of the living room space R11and exhausts air (EA) to the outdoors.

The second exhaust unit110B is provided with a fan11, a second heat exchanger12, a control unit113B, and a temperature detecting unit14, and takes in return air (RA) from a ventilation port91B of the living room space R11and exhausts air (EA) to the outdoors.

The control unit113A and the control unit113B control the configuration in each exhaust unit. Further, the control unit113A and the control unit113B transmit the detection result obtained by the temperature detecting unit14or the like in each exhaust unit to the control unit152of the compressor unit150. The control unit152of the compressor unit150recognizes the current status from the detection result and transmits the recognition result to the upper level control device100. Thus, the upper level control device100can recognize the status of the first exhaust unit110A and the second exhaust unit110B.

The upper level control device100performs various kinds of control in order to link the operation of the ventilation apparatus1B with the operation of the air conditioner2B.

The upper level control device100receives the status of the air conditioner2B from the control unit171of the outdoor unit170, and receives the status of the ventilation apparatus1B from the control unit152of the compressor unit150. The upper level control device100performs various kinds of control according to the status of the air conditioner2B and the status of the ventilation apparatus1B.

When the upper level control device100recognizes that the second heat exchanger12of either the first exhaust unit110A or the second exhaust unit110B is frosted, the upper level control device100performs control to stop the circulation of refrigerant with respect to the frosted second heat exchanger12. In the present embodiment, the circulation of refrigerant can be stopped for each second heat exchanger12. The refrigerant circuit will now be described.

FIG.3is a diagram illustrating a refrigerant circuit according to the second embodiment. In the example illustrated inFIG.3, a flow of refrigerant when the second heat exchanger12of the exhaust units110A and110B functions as an evaporator is illustrated. The same reference numerals are assigned to the configurations similar to that of the above-described embodiment, and the description thereof is omitted.

In the example illustrated inFIG.3, air supply units120A and120B, exhaust units110A and110B, and a compressor unit150are provided.

The air supply units120A and120B include a fan21, a first heat exchanger22, a control unit123, a temperature detecting unit24, a driving motor25, and an electric valve26.

The driving motor25controls the air volume of the fan21by the control unit123.

The electric valve26functions as an expansion valve for adjusting the opening degree of the flow path through which the refrigerant flows in order to reduce the pressure of the refrigerant, and switches whether to reduce the pressure based on the control unit123. The electric valve26functions to reduce the pressure when the first heat exchanger22functions as an evaporator and not to reduce the pressure when the first heat exchanger22functions as a condenser. As illustrated inFIG.3, the electric valve (expansion valve)26is provided in a flow path connected to the first heat exchanger22for each first heat exchanger.

The exhaust unit110A includes a fan11, a second heat exchanger12, a control unit113A, a temperature detecting unit14, a driving motor15, and an electric valve16.

The exhaust unit110B includes a fan11, a second heat exchanger12, a control unit113B, a temperature detecting unit14, a driving motor15, and an electric valve16.

The driving motor15controls the air volume of the fan11by the control unit113A or the control unit113B.

The electric valve16functions as an expansion valve for adjusting the opening degree of the flow path through which the refrigerant flows in order to reduce the pressure of the refrigerant, and switches whether to reduce the pressure based on control by the control unit113A or the control unit113B. The electric valve16functions to reduce the pressure when the second heat exchanger12functions as an evaporator and not to reduce the pressure when the second heat exchanger12functions as a condenser. As illustrated inFIG.3, the electric valve (expansion valve)16is provided in a flow path connected to the second heat exchanger12for each second heat exchanger.

The compressor unit150is provided with a driving motor51, a control unit152, a compressor53, a four-way valve54, an electric valve55, and a bypass electric valve56.

The compressor53compresses the refrigerant flowing through the refrigerant circuit.

The driving motor51is an actuator for driving the compressor53. The driving motor51according to the present embodiment drives the compressor53at a rotational speed controlled by the control unit152.

The control unit152controls the configuration inside the compressor unit150. For example, the control unit152controls the driving motor51and the four-way valve54as follows.

The four-way valve54functions as a valve for switching the outflow destination of the refrigerant compressed by the compressor53from the refrigerant circuit F101and the refrigerant circuit F104. For example, when the second heat exchanger12functions as an evaporator based on the control of the control unit152, the four-way valve54is switched so that the refrigerant compressed by the compressor53flows into the refrigerant circuit F101.

The electric valve55functions as a valve for controlling the opening and closing of the refrigerant circuit according to the control from the control unit152. When the second heat exchanger12functions as an evaporator, the electric valve55is in a closed state in which no refrigerant flows.

The control units113A and113B output the detection result obtained by the temperature detecting unit14to the control unit152of the compressor unit150.

The control unit152of the compressor unit150determines, from the input detection result, whether the second heat exchanger12satisfies a predetermined reference indicating frosting. The description of the predetermined reference is omitted as the predetermined reference is the same as in the first embodiment.

The control units113A,113B of the exhaust units110A,110B according to the present embodiment report, to the upper level control device100, that the second heat exchanger12of the exhaust units110A,110B has frosted when it is determined that the predetermined reference has been satisfied. Thus, the upper level control device100can recognize the frosting of the second heat exchanger12.

Then, as control for defrosting the second heat exchanger12, the upper level control device100outputs a control signal (an example of a predetermined instruction) for closing the electric valve16(an example of the first valve part) existing upstream of the second heat exchanger12, to the exhaust unit (the first exhaust unit110A or the second exhaust unit110B) including the frosted second heat exchanger12.

The control unit (the control unit113A or the control unit113B) of the exhaust unit (the first exhaust unit110A or the second exhaust unit110B) receives a control signal for closing the electric valve16from the upper level control device100via the compressor unit150. In this case, the control unit (the control unit113A or the control unit113B) of the exhaust unit (the first exhaust unit110A or the second exhaust unit110B) outputs a signal for closing the electric valve16, to an actuator (not illustrated) for adjusting the opening of the electric valve16(an example of an actuator for controlling the state of the refrigerant in a refrigerant circuit), thereby controlling the electric valve16to be closed.

When the electric valve16is closed, the inflow of refrigerant into the second heat exchanger12located downstream of the electric valve16is prevented. As in the above embodiment, the rotation control of the fan11is maintained.

That is, in the present embodiment, as an example of the control for defrosting the frosted second heat exchanger12when there are a plurality of the second heat exchangers12, the electric valve16upstream of the frosted second heat exchanger12is closed to stop the inflow of the refrigerant to the second heat exchanger12, and warm air in the living room space R11is allowed to flow through the second heat exchanger12to raise the temperature of the refrigerant flowing through the second heat exchanger, so that defrosting can be performed.

In the present embodiment, by using warm air (heat) in the living room space R11for defrosting the second heat exchanger12, defrosting with high heat efficiency can be performed.

Modified Example 1 of the Second Embodiment

In the above-described embodiment, an example of controlling the electric valve16corresponding to the second heat exchanger12to a closed state when the second heat exchanger12frosts has been described. Incidentally, if a plurality of the electric valves16are controlled to a closed state when a plurality of the second heat exchangers12become frosted, the air conditioning capability of the ventilation apparatus1B decreases. Therefore, in the present modified example, an example will be described in which control is implemented such that defrosting is not performed simultaneously by a plurality of the second heat exchangers12when a plurality of the second heat exchangers12become frosted.

FIG.4is a sequence diagram illustrating the flow of processing performed between the upper level control device100, the compressor unit150, and the exhaust units110A and110B when frosting occurs in each of the exhaust units in the exhaust unit group according to the modified example 1 of the second embodiment.

First, the control unit113A of the first exhaust unit110A acquires the temperature of the refrigerant of the second heat exchanger12from the temperature detecting unit14(S1401).

Then, the control unit113A reports the detected temperature of the refrigerant to the control unit152of the compressor unit150(S1402).

The control unit113B of the second exhaust unit110B acquires the temperature of the refrigerant of the second heat exchanger12from the temperature detecting unit14(S1411).

The control unit113B reports the detected temperature of the refrigerant to the control unit152of the compressor unit150(S1412).

The control unit152of the compressor unit150determines whether the second heat exchanger12of the first exhaust unit110A and the second exhaust unit110B satisfies a predetermined reference indicating frosting, based on the detected temperature of the refrigerant received from the control unit113A of the first exhaust unit110A and the control unit113B of the second exhaust unit110B (S1421). In the example illustrated inFIG.4, it is determined that each of the second heat exchangers12of the first exhaust unit110A and the second exhaust unit110B satisfies the predetermined reference. The predetermined reference is similar to that of the above-described embodiment, so the description thereof will be omitted.

The control unit152of the compressor unit150reports, to the upper level control device100, the determination result indicating frosting (S1422).

The upper level control device100determines the order in which frosting avoidance is controlled for the first exhaust unit110A and the second exhaust unit110B based on the received determination result (S1431). Any method may be used to determine the order. For example, control may be implemented such that frosting avoidance is performed first for the exhaust unit that is more highly likely to frost, or frosting avoidance may be performed according to a priority order assigned in advance to the first exhaust unit110A and the second exhaust unit110B. The example illustrated inFIG.4is an example in which it is determined to perform the defrosting in the order of the first exhaust unit110A and then the second exhaust unit110B.

The upper level control device100transmits a signal indicating control to close the electric valve16of the first exhaust unit110A to the control unit152of the compressor unit150(S1432).

The control unit152of the compressor unit150transmits a signal indicating an instruction for control to close the electric valve16to the control unit113A of the first exhaust unit110A (S1423).

Thus, the control unit113A of the first exhaust unit110A controls the electric valve16to be closed (S1403). Thus, the inflow of refrigerant into the second heat exchanger12of the first exhaust unit110A is prevented.

After a predetermined time (for example, an appropriate time for the second heat exchanger12of the first exhaust unit110A to complete defrosting) has passed, the upper level control device100transmits a signal indicating control to open the electric valve16of the first exhaust unit110A to the control unit152of the compressor unit150(S1433).

Then, the control unit152of the compressor unit150transmits a signal indicating an instruction for control to open the electric valve16to the control unit113A of the first exhaust unit110A (S1424).

As a result, the control unit113A of the first exhaust unit110A implements control to open the electric valve16(S1404). As a result, the inflow of refrigerant into the second heat exchanger12of the first exhaust unit110A is resumed.

The upper level control device100transmits a signal indicating an instruction for control to close the electric valve16of the second exhaust unit110B to the control unit152of the compressor unit150(S1434).

The control unit152of the compressor unit150transmits a signal indicating an instruction for control to close the electric valve16to the control unit113B of the second exhaust unit110B (S1425).

Thus, the control unit113B of the second exhaust unit110B controls the electric valve16to be closed (S1413). Thus, the inflow of refrigerant into the second heat exchanger12of the second exhaust unit110B is prevented.

Thus, when the plurality of second heat exchangers12are determined to be in a frosted state, the upper level control device100transmits a signal to close the plurality of electric valves16corresponding to the plurality of second heat exchangers determined to be in a frosted state according to a predetermined order.

Accordingly, when the control unit152and the upper level control device100of the compressor unit150according to the present embodiment determines that the predetermined reference is satisfied while the plurality of second heat exchangers12are functioning as evaporators, the defrosting of the second heat exchanger12can be implemented by preventing the inflow of the refrigerant to any one of the plurality of second heat exchangers12and maintaining the inflow of warm air from the living room space R11by the fan11.

Further, by defrosting each of the plurality of exhaust units according to the predetermined order, the present embodiment prevents the simultaneous defrosting of the second heat exchangers12of the plurality of exhaust units, thereby further preventing the decrease of the room temperature of the living room space R11.

Third Embodiment

Another method may be used for defrosting the second heat exchanger12. Therefore, in the third embodiment, another aspect for adjusting the opening degree of the electric valve16inside the exhaust units110A and110B will be described. The configuration of the upper level control device100, the air conditioner2B, and the ventilation apparatus1B according to the third embodiment will be the same as that of the second embodiment, and the description thereof will be omitted.

As illustrated inFIG.3, when the second heat exchanger12functions as an evaporator, the electric valve16(an example of the second valve part) is provided between the first heat exchanger22and the second heat exchanger12.

When the second heat exchanger12functions as an evaporator, the electric valve16functions as a valve part for reducing the pressure of a liquid high-pressure refrigerant flowing from the first heat exchanger22in order to make the refrigerant easy to evaporate according to the control of the control units113A and113B. As the opening degree of the electric valve16decreases, the pressure is reduced, and the temperature of the refrigerant decreases. That is, as the opening degree of the electric valve16increases, the temperature of the refrigerant increases.

While the second heat exchanger12is functioning as an evaporator, the upper level control device100recognizes that the second heat exchanger12is frosted from the determination result from the control unit152of the compressor unit150. The determination by the control unit152of the compressor unit150is similar to the above-described embodiment and modified example, and descriptions thereof will be omitted.

The upper level control device100outputs a control signal for increasing the opening degree of the electric valve16to the exhaust unit (for example, the first exhaust unit110A or the second exhaust unit110B) including the second heat exchanger12which has been determined to be frosted, as compared with that before determination of frosting.

When the control signal is received, the control unit113A of the first exhaust unit110A or the113B of the second exhaust unit110B outputs a control signal (an example of a predetermined instruction) to an actuator (not illustrated) (an example of an actuator which controls the state of the refrigerant in a refrigerant circuit) which adjusts the opening degree of the electric valve16as compared with that before determination of frosting to increase the opening degree of the electric valve16.

As a result, the temperature of the refrigerant flowing to the second heat exchanger12rises. Warm air flows into the second heat exchanger12from the living room space R11by the fan11. As a result, defrosting of the second heat exchanger12can be implemented.

Modified Example 1 of the Third Embodiment

The second heat exchanger12may be defrosted by using a method other than the above-described embodiment. Therefore, in the modified example 1 of the third embodiment, an example of adjusting the pressure of the refrigerant by an electric valve provided downstream of the exhaust unit will be described.

The configuration of the modified example 1 of the third embodiment is similar to that of the second embodiment described above except for the refrigerant circuit.

FIG.5is a diagram illustrating the refrigerant circuit of the modified example 1 of the third embodiment. The example illustrated inFIG.5illustrates the flow of refrigerant when the second heat exchanger12of the exhaust units110A and110B functions as an evaporator. Note that that the same reference numerals are assigned to the configuration similar to the above-described embodiment, and the description thereof will be omitted.

In the example illustrated inFIG.5, when the second heat exchanger12of the exhaust units110A and110B functions as an evaporator, electric valves161and162(an example of the third valve part) are provided downstream from the second heat exchanger12of each of the exhaust units110A and110B.

The electric valves161and162are provided downstream of the refrigerant flowing through the second heat exchanger12, and have a mechanism for adjusting the flow rate of the refrigerant.

While the second heat exchanger12is functioning as an evaporator, the control unit152of the compressor unit150according to the present modified example determines whether the predetermined reference indicating frosting of the second heat exchanger12is satisfied based on the temperature of the refrigerant flowing through the second heat exchanger12. Note that that the predetermined reference is the same as that of the above-described embodiment, and the description thereof is omitted. The control unit152of the compressor unit150reports, to the upper level control device100, the determination result.

In the present modified example, when the upper level control device100recognizes that there is a second heat exchanger12that satisfies the predetermined reference, the upper level control device100outputs a control signal (predetermined instruction) to make the opening degree of the electric valve (the electric valve161or the electric valve162) smaller than before the predetermined reference is satisfied, to the control unit (the control unit113A or the control unit113B) of the exhaust unit (for example, the first exhaust unit110A or the second exhaust unit110B) that includes the second heat exchanger12. Thus, the control unit (the control unit113A or the control unit113B) outputs a control signal (an example of a predetermined instruction) to an actuator (an example of an actuator for controlling the state of the refrigerant in a refrigerant circuit) for adjusting the opening degree of the electric valve (the electric valve161or the electric valve162), thereby reducing the opening degree of the electric valve (the electric valve161or the electric valve162).

Thus, in the present modified example, an electric valve for adjusting the flow rate of refrigerant is provided on the downstream side of the second heat exchanger12in addition to the electric valve16provided on the upstream side of the second heat exchanger12.

By reducing the opening degree of the electric valve (the electric valve161or the electric valve162), the pressure of refrigerant flowing through the second heat exchanger12located on the upstream side of the electric valve (the electric valve161or the electric valve162) can be increased. As a result, the evaporation temperature of refrigerant flowing through the second heat exchanger12can be increased. Warm air in the living room space R11continues to flow into the second heat exchanger12by the fan11. Therefore, defrosting of the second heat exchanger12can be implemented.

Fourth Embodiment

A method other than the above-described embodiment may be used to defrost the second heat exchanger12. In the fourth embodiment, an example in which a bypass flow path (an example of bypass pipe) is provided in the refrigerant circuit will be described. In the fourth embodiment, an exhaust unit110B is reduced by one unit compared with the third embodiment, and two air supply units120A and120B and one exhaust unit110A are provided. The other configurations are the same as those of the third embodiment and the description thereof will be omitted.

FIG.6is a diagram illustrating a refrigerant circuit according to the fourth embodiment. In the example illustrated inFIG.6, a flow of refrigerant is illustrated when the second heat exchanger12of the exhaust unit110A functions as an evaporator. Note that that the same reference numerals are assigned to the configuration similar to the above-described embodiment, and the description thereof will be omitted.

In the example illustrated inFIG.6, the air supply units120A and120B, the exhaust unit110A, and the compressor unit150are provided.

The air supply units120A and120B are provided with a fan21, a first heat exchanger22, a control unit23, a temperature detecting unit24, a driving motor25, and an electric valve26.

The exhaust unit110A is provided with a fan11, a second heat exchanger12, a control unit113A, a temperature detecting unit14, a driving motor15, and an electric valve16.

In the present modified example, while the second heat exchanger12functions as an evaporator, the control unit113A of the exhaust unit110A outputs the detection result (the temperature of the refrigerant flowing through the second heat exchanger12) of the temperature detecting unit14to the control unit152of the compressor unit150.

The control unit152of the compressor unit150determines whether the predetermined reference indicating frosting of the second heat exchanger12is satisfied based on the input temperature of the refrigerant flowing through the second heat exchanger12. Note that the predetermined reference is the same as in the above-described embodiment so the description thereof is omitted. The control unit152of the compressor unit150reports, to the upper level control device100, the determination result.

In the present modified example, when the upper level control device100recognizes the existence of the second heat exchanger12satisfying a predetermined standard, the upper level control device100outputs a control signal for passing the refrigerant into the bypass flow path F106to the control unit152of the compressor unit150as defrosting control of the second heat exchanger12.

The compressor unit150is provided with a driving motor51, a control unit152, a compressor53, a four-way valve54, an electric valve55, and a bypass electric valve156.

The control unit152controls the configuration of the inside of the compressor unit150. For example, the control unit152controls the driving motor51and the four-way valve54described below.

In the present embodiment, when the second heat exchanger12functions as an evaporator, a bypass flow path F106is provided to allow the refrigerant compressed by the compressor53to flow directly to the second heat exchanger12in order to raise the temperature of the refrigerant flowing through the second heat exchanger12.

The bypass flow path F106is provided as a flow path of refrigerant bypassing between the compressor53and the four-way valve54and the refrigerant circuit F103. That is, while the second heat exchanger12functions as an evaporator, the bypass flow path F106functions as a pipe for passing refrigerant to the second heat exchanger12without going through the first heat exchanger22.

The bypass electric valve156functions as a valve for switching whether or not to pass the refrigerant to the bypass flow path F106in accordance with the control from the control unit152.

Specifically, when the upper level control device100determines that the second heat exchanger12is frosted, the upper level control device100outputs a control signal for passing the refrigerant to the bypass flow path F106to the control unit152of the compressor unit150.

When the control signal for passing the refrigerant to the bypass flow path F106is received from the upper level control device100, the control unit152of the compressor unit150outputs a control signal (an example of a predetermined instruction) to an actuator (not illustrated) (an example of an actuator that controls the state of the refrigerant in the refrigerant circuit) that controls the opening degree of the bypass electric valve156, thereby controlling the bypass electric valve156to be opened.

When the bypass electric valve156is opened, the refrigerant that has become a high-temperature and high-pressure gas by being compressed by the compressor53flows into the refrigerant circuit F103through the bypass flow path F106. A part of the refrigerant that has become a high-temperature and high-pressure gas by passing through the bypass flow path F106flows through the refrigerant circuit F103without passing through the first heat exchanger22. As a result, the temperature of the refrigerant flowing through the refrigerant circuit F103rises. Accordingly, the refrigerant with the increased temperature flows through the second heat exchanger12.

That is, in the present modified example, when the predetermined standard is satisfied, a part of the refrigerant that has become a high-temperature and high-pressure gas by the compressor53is controlled to flow through the bypass flow path F106to the second heat exchanger12. With this control, warm air in the living room space R11flows to the second heat exchanger12by the fan11. As a result, defrosting of the second heat exchanger12can be implemented.

Modified Example 1 of the Fourth Embodiment

The second heat exchanger12may be defrosted by using a method other than the above-described embodiment and modified example. In the modified example 1 of the fourth embodiment, an example in which a heater is provided in the refrigerant circuit will be described. The modified example 1 of the fourth embodiment is an example in which the bypass flow path F106and the bypass electric valve56is removed as compared to the fourth embodiment, and instead, a heater is provided on the refrigerant circuit (for example, the refrigerant circuit F103). The other configurations are the same as those of the fourth embodiment and the description thereof will be omitted.

In the present modified example, while the second heat exchanger12functions as an evaporator, the control unit113A of the exhaust unit110A outputs the detection result of the temperature detecting unit14(the temperature of the refrigerant flowing through the second heat exchanger12) to the control unit152of the compressor unit150.

Based on the input temperature of the refrigerant flowing through the second heat exchanger12, the control unit152of the compressor unit150determines whether the predetermined reference indicating frosting of the second heat exchanger12are satisfied. Note that that the predetermined reference is the same as that of the above-described embodiment, and the description thereof is omitted. The control unit152of the compressor unit150reports, to the upper level control device100, the determination result.

In the present modified example, when the upper level control device100recognizes the existence of the second heat exchanger12that satisfies the predetermined reference, the upper level control device100instructs the control unit152of the compressor unit150to start heating the refrigerant circuit by the heater as defrosting control of the second heat exchanger12.

When the control unit152of the compressor unit150receives an instruction to start heating from the upper level control device100, the control unit152starts heating the heater.

As a result, the temperature of the refrigerant flowing through the refrigerant circuit F103rises. Accordingly, the refrigerant with the increased temperature flows into the second heat exchanger12. With this control, warm air in the living room space R11flows into the second heat exchanger12by the fan11. As a result, defrosting of the second heat exchanger12can be implemented.

Modified Example 2 of the Fourth Embodiment

The second heat exchanger12may be defrosted by using a method other than the above-described embodiment and modified example. In the modified example 2 of the fourth embodiment, an example of increasing the pressure of the refrigerant flowing through the refrigerant circuit will be described. The modified example 2 of the fourth embodiment will be an example including a configuration similar to that of the second embodiment. The other configurations are similar to those of the fourth embodiment and the description thereof will be omitted.

In the present modified example, while the second heat exchanger12is functioning as an evaporator, the control unit113A of the exhaust unit110A outputs the detection result of the temperature detecting unit14(the temperature of the refrigerant flowing through the second heat exchanger12) to the control unit152of the compressor unit150.

Based on the input temperature of the refrigerant flowing through the second heat exchanger12, the control unit152of the compressor unit150determines whether the predetermined reference indicating frosting of the second heat exchanger12are satisfied. Note that that the predetermined reference is the same as that of the above-described embodiment, and the description thereof is omitted. The control unit152of the compressor unit150reports, to the upper level control device100, the determination result.

In the present modified example, when the upper level control device100recognizes the existence of the second heat exchanger12that satisfies the predetermined reference, the upper level control device100instructs the control unit152of the compressor unit150to increase the pressure of the compressor as defrosting control of the second heat exchanger12.

When the control unit152of the compressor unit150receives an instruction to increase the pressure from the upper level control device100, the control unit152outputs a control signal to increase the pressure as compared with before the determination of frosting to the driving motor51, thereby controlling to increase the pressure of the refrigerant flowing in the refrigerant circuit.

As a result, the pressure of the refrigerant flowing in the refrigerant circuit F103increases, and the temperature of the refrigerant also increases. The refrigerant whose temperature has increased flows into the second heat exchanger12, and warm air in the living room space R11flows into the second heat exchanger12by the fan11. Therefore, defrosting of the second heat exchanger12can be implemented.

Fifth Embodiment

A method other than the above-described embodiment may be used to defrost the second heat exchanger12. In the fifth embodiment, an example of reverse cycling the flow of the refrigerant circuit will be described. In the fifth embodiment, the configuration is similar to the third embodiment, and the description will be omitted.

In the present embodiment, while the second heat exchanger12functions as an evaporator, the control unit113A of the exhaust unit110A outputs the detection result of the temperature detecting unit14(the temperature of the refrigerant flowing through the second heat exchanger12) to the control unit152of the compressor unit150.

Based on the input temperature of the refrigerant flowing through the second heat exchanger12, the control unit152of the compressor unit150determines whether the predetermined reference indicating frosting of the second heat exchanger12is satisfied. Note that that the predetermined reference is the same as that of the above-described embodiment, and the description thereof is omitted. The control unit152of the compressor unit150reports, to the upper level control device100, the determination result.

In the present embodiment, when the upper level control device100recognizes the existence of the second heat exchanger12that satisfies the predetermined reference, the upper level control device100instructs the control unit152of the compressor unit150to reverse cycle the flow of refrigerant as defrosting control of the second heat exchanger12.

When the control unit152of the compressor unit150receives an instruction to reverse cycle the flow of refrigerant from the upper level control device100, the control unit152outputs a control signal (an example of a predetermined instruction) to switch the flow of the four-way valve54to an actuator (not illustrated) (an example of an actuator that controls the state of the refrigerant in the refrigerant circuit) that drives the four-way valve54provided in the refrigerant circuit as illustrated inFIG.3. As a result, the refrigerant compressed at the compressor is switched to flow to the exhaust units110A and110B. At this time, the opening degrees of the electric valves16and26are also adjusted.

The second heat exchanger12of the exhaust units110A and110B functions as a condenser when the compressed refrigerant flows in. On the other hand, the first heat exchanger22of the air supply units120A and120B functions as an evaporator.

The control described above causes the refrigerant flowing through the refrigerant circuit to reverse cycle, and the second heat exchanger12functions as a condenser, thereby increasing the temperature of the refrigerant flowing through the second heat exchanger12. Warm air in the living room space R11flows into the second heat exchanger12by the fan11. As a result, defrosting of the second heat exchanger12can be implemented.

Modified Example 1 of the Fifth Embodiment

In the fifth embodiment, the flow of the refrigerant circuit is reverse cycled, but the air flow is not switched. Therefore, in the modified example 1 of the fifth embodiment, an example of reversing the cycle and switching the air flow will be described. The modified example 1 of the fifth embodiment has the same configuration as that of the fifth embodiment.

In the present modified example, when the upper level control device100recognizes the existence of the second heat exchanger12that satisfies the predetermined reference by the same procedure as that of the fifth embodiment, the upper level control device100instructs the control unit152of the compressor unit150to reverse cycle the flow of refrigerant, and outputs a control signal to the control unit123of the air supply units120A and120B to switch the flow of air by the fan21so as to exhaust the air from the living room space R11to the outdoors via the first air supply flow path P101and the second air supply flow path P102.

In the present modified example, warm air can flow into the first heat exchanger22functioning as an evaporator by the switching control of the air flow described above, and, therefore, the temperature of the refrigerant flowing through the refrigerant circuit can be increased. By increasing the temperature of the refrigerant flowing through the first heat exchanger22functioning as an evaporator, the temperature of the refrigerant flowing through the second heat exchanger12can also be increased. Therefore, the temperature of the refrigerant flowing through the second heat exchanger12can be further increased to improve the defrosting efficiency.

Modified Example 2 of the Fifth Embodiment

In modified example 1 of the fifth embodiment, an example of switching the air flow at the air supply units120A and120B has been described. However, in modified example 1 of the fifth embodiment, the air flow at the exhaust units110A and110B has been maintained under the same control as before frosting. Therefore, in modified example 2 of the fifth embodiment, an example in which the air flow at the exhaust units110A and110B is also switched will be described. Note that modified example 2 of the fifth embodiment has the same configuration as that of the fifth embodiment.

In the present modified example, when the upper level control device100recognizes the existence of the second heat exchanger12satisfying the predetermined reference by the same procedure as in the fifth embodiment, the upper level control device100instructs the control unit152of the compressor unit150to reverse cycle the flow of refrigerant, and outputs a control signal to the control unit123of the air supply units120A and120B to switch the flow of air by the fan21so as to exhaust the air from the living room space R11to the outdoors via the first air supply flow path P101and the second air supply flow path P102. The upper level control device100then outputs a control signal to the control unit113A of the exhaust unit110A and the control unit113B of the exhaust unit110B to switch the flow of air by the fan11so as to supply the air from the outdoors to the living room space R11via the first exhaust flow path P103and the second exhaust flow path P104.

In the present modified example, by the air flow switching control described above, warm air flows into the first heat exchanger22functioning as an evaporator, and the second heat exchanger12functioning as a condenser receives an inflow of air from the outdoors.

That is, in the present modified example, the refrigerant cycle and the air supply/exhaust are all switched, and, therefore, ventilation can be continued while heat exchange is performed, and the comfort of the living room space R11can be maintained while defrosting the second heat exchanger12.

Sixth Embodiment

A method other than those of the above-described embodiment may be used to defrost the second heat exchanger12. In the sixth embodiment, an example of adjusting the air flow to the exhaust unit will be described.

FIG.7is a diagram illustrating a configuration example of a ventilation apparatus and an air conditioner according to the sixth embodiment. In the example illustrated inFIG.7, a ventilation apparatus1C and an air conditioner2are provided for air conditioning an indoor space. The ventilation apparatus1C includes an exhaust unit210and an air supply unit20, which are controlled differently from the above-described embodiment. The same reference numerals are assigned to the configuration similar to the above-described embodiment, and the description thereof is omitted.

The return air flow path P202(an example of the second air flow path) is a flow path for exhausting air (return air) taken in from the ventilation port91of the living room space R11to the outdoors after passing through the exhaust unit210including the second heat exchanger12.

In the return air flow path P202according to the present embodiment, the air intake destination is branched into two in order to allow air to be taken in from a plurality of rooms. Each of the paths is referred to as a first return air branch path P202A (an example of the second air flow path) and a second return air branch path P202B (an example of the third air flow path).

The first return air branch path (an example of the second air flow path) P202A is an air flow path provided for exhausting air taken in from the living room space R11to the outdoors after passing through the exhaust unit210including the second heat exchanger12. The first return air branch path P202A takes in air from the ventilation port91provided in the ceiling of the living room space R11.

The second return air branch path (an example of the third air flow path) P202B is an air flow path provided for exhausting air taken in from the ceiling space R12to the outdoors after passing through the exhaust unit210having the second heat exchanger12. An example is described in which the space that is the air intake destination of the second return air branch path P202B according to the present embodiment is the ceiling space R12, which is a different space from that of the first return air branch path P202A. However, the space that is the air intake destination is not limited to the ceiling space R12, and may be an underfloor space. As described above, the air intake destination of the second return air branch path P202B may be a space different from the living room space R11.

An opening/closing damper240is provided at the tip of the second return air branch path P202B. The opening/closing damper240is usually closed. The opening/closing damper240(an example of the first guide mechanism) can adjust the air volume taken in from the ceiling space R12by controlling from the control unit213provided in the exhaust unit210through the signal line S202.

The exhaust unit210includes a control unit213which performs processing different from the above-described embodiment.

The control unit213controls the configuration inside the exhaust unit210. The control unit213performs various kinds of control according to the detection result obtained by the temperature detecting unit14. For example, the control unit213adjusts the function of the second heat exchanger12as a condenser or evaporator according to the detection result obtained by the temperature detecting unit14.

Further, the control unit213according to the present embodiment can adjust the air volume taken in from the ceiling space R12by controlling the opening/closing damper240based on the detection result obtained by the temperature detecting unit14.

In the present embodiment, while the second heat exchanger12is functioning as an evaporator, the control unit213of the exhaust unit210determines whether the predetermined reference indicating frosting of the second heat exchanger12is satisfied from the detection result obtained by the temperature detecting unit14. Note that that the predetermined reference is the same as that of the above-described embodiment, and the description thereof is omitted.

The control unit213of the exhaust unit210according to the present embodiment detects the temperature of air in the ceiling space R12when it is determined that the predetermined standard is satisfied. When it is determined that the temperature of air in the ceiling space R12is higher than the temperature of air in the living room space R11, the control unit213implements control to open the opening/closing damper240so that the air present in the ceiling space R12is guided to the second heat exchanger12through the second return air branch path P202B as defrosting control of the second heat exchanger12. That is, warm air is gathered in the ceiling space R12because the ceiling space R12exists above the living room space R11. Therefore, when it is determined that the second heat exchanger12is frosted, the opening/closing damper240is controlled to open. By this control, the air, in which the warm air existing in the ceiling space R12and the air existing in the living room space R11are mixed, is guided to the second heat exchanger12.

As an example of the control for increasing the temperature of the refrigerant flowing through the second heat exchanger12, the control unit213according to the present embodiment implements control such that the warm air in the ceiling space R12flows to the second heat exchanger12. As a result, defrosting of the second heat exchanger12can be implemented. Note that that the output of the instruction to the actuator for controlling the state of the refrigerant in the refrigerant circuit so as to raise the temperature of the refrigerant flowing into the second heat exchanger12may be performed by any of the methods described in the above embodiment, and the description thereof will be omitted.

Modified Example 1 of the Sixth Embodiment

In the embodiment described above, an example in which warm air in the ceiling space R12is mixed with air in the living room space R11by using the opening/closing damper240and controlled to flow to the second heat exchanger12has been described. However, the sixth embodiment is not limited to a method in which warm air in the ceiling space R12is mixed with air in the living room space R11. In the modified example 1 of the sixth embodiment, an example in which only warm air in the ceiling space R12is controlled to flow to the second heat exchanger12will be described.

In the present modified example, as in the above-described embodiment, the return air flow path P202branches into a first return air branch path P202A (an example of a second air flow path) and a second return air branch path P202B (an example of a third air flow path).

In the above-described embodiment, the opening/closing damper240is provided at the second return air branch path P202B, but in the present modified example, the opening/closing damper (an example of the second guide mechanism) is also provided at the first return air branch path P202A. Otherwise, the present modified example is the same as in the sixth embodiment.

The opening/closing damper provided at the first return air branch path P202A is usually opened. Thus, the return air (RA) of the living room space R11can be taken in. The opening/closing damper provided at the first return air branch path P202A can adjust the air volume taken in from the living room space R11by control via a signal line (not illustrated) from the control unit213provided in the exhaust unit210.

The control unit213of the exhaust unit210according to the present modified example detects the temperature of the air in the ceiling space R12when it is determined that the second heat exchanger12satisfies a predetermined reference for frosting. When it is determined that the temperature of the air in the ceiling space R12is higher than the temperature of the air in the living room space R11, the control unit213controls to open the opening/closing damper240and to close the opening/closing damper provided at the first return air branch path P202A.

Thus, the intake of return air (RA) in the living room space R11is prevented, and warm air existing in the ceiling space R12flows into the second heat exchanger12. Therefore, the defrosting efficiency of the second heat exchanger12can be improved.

Seventh Embodiment

A method other than the sixth embodiment described above may be used to adjust the air flow to the exhaust unit. Therefore, in the seventh embodiment, another aspect of adjusting the air flow to the exhaust unit will be described.

FIG.8is a diagram illustrating a configuration example of a ventilation apparatus and an air conditioner according to the seventh embodiment. In the example illustrated inFIG.8, a ventilation apparatus1D and an air conditioner2are provided for air conditioning an indoor space. The ventilation apparatus1D has an exhaust unit310which performs control different from the above-described embodiment. The same reference numerals are assigned to the configuration similar to the above-described embodiment, and the description thereof is omitted.

The first return air flow path P301(an example of the second air flow path) is a flow path for exhausting air (return air) taken in from the ventilation port91of the living room space R11to the outdoors after passing through the exhaust unit310including the second heat exchanger12.

A first opening/closing damper341(an example of a switching mechanism) is provided at the tip of the first return air flow path P301. The first opening/closing damper341is usually open. The first opening/closing damper341can adjust the air volume taken in from the living room space R11by controlling from the control unit313provided in the exhaust unit310through the signal line S302.

The second return air flow path P302is a flow path for exhausting the air taken in from the outdoors (return air) to the outdoors after passing through the exhaust unit310including the second heat exchanger12.

A second opening/closing damper342(an example of a switching mechanism) is provided on the flow path of the second return air flow path P302(an example of the second air flow path). The second opening/closing damper342is usually closed. The second opening/closing damper342can adjust the air volume taken in from the outdoors by controlling from the control unit313provided in the exhaust unit310through the signal line S202.

The first opening/closing damper341and the second opening/closing damper342function as a mechanism for switching whether air flowing to the second heat exchanger12is supplied from the living room space R11or from the outdoors.

The exhaust unit310includes a control unit313for performing a process different from the above-described embodiment.

The control unit313controls the configuration inside the exhaust unit310. The control unit313performs various kinds of control according to the detection result obtained by the temperature detecting unit14. For example, the control unit313adjusts the function of the second heat exchanger12as a condenser or evaporator according to the detection result obtained by the temperature detecting unit14.

Further, the control unit313according to the present embodiment controls the first opening/closing damper341and the second opening/closing damper342based on the detection result obtained by the temperature detecting unit14, thereby changing the intake destination of air flowing into the second heat exchanger12.

In the present embodiment, while the second heat exchanger12is functioning as an evaporator, the control unit313of the exhaust unit310determines whether the predetermined reference indicating frosting of the second heat exchanger12is satisfied from the detection result obtained by the temperature detecting unit14. Note that that the predetermined reference is the same as that of the above-described embodiment, and the description thereof is omitted.

When the control unit313of the exhaust unit310according to the present embodiment determines that the predetermined reference is satisfied, the control unit313detects the temperature of the living room space R11and the outside air. When the temperature of the air in the living room space R11is higher than that of the outside air, the first opening/closing damper341and the second opening/closing damper342are not controlled.

When it is determined that the temperature of the outside air is higher than the temperature of the air in the living room space R11, the control unit313performs defrosting control of the second heat exchanger12to open the second opening/closing damper342so that the air existing in the outdoors is guided to the second heat exchanger12through the second return air flow path P302. Further, the control unit313performs closing control of the first opening/closing damper341to prevent the inflow of the air from the living room space R11to the second heat exchanger12through the first return air flow path P301.

That is, the control unit313controls the first opening/closing damper341and the second opening/closing damper342to supply air starting from air having a higher detected temperature between the air from the living room space R11and the air from the outdoors, when the second heat exchanger12frosts while the second heat exchanger12functions as an evaporator.

When it is possible to take in warm air from the outdoors, the control unit313controls the first opening/closing damper341and the second opening/closing damper342to take in air from the outdoors.

In the present embodiment, for example, when the control unit313determines that the air temperature TC>the air temperature TB>the air temperature TA>is satisfied by comparing the air temperature TA around the intake port of the first heat exchanger22, the air temperature TB in the living room space R11, and the air temperature TC around the outlet of the second heat exchanger12, the aforementioned processing is performed.

Examples in which the air temperature TC is higher than the air temperature TB and the air temperature TA includes when the outlet of the second heat exchanger12is located on the south side of the building and the surrounding air is warmed by sunlight, etc., when the inlet of the first heat exchanger22is located on the north side of the building and the surrounding air is cooled by the shade, when the snow that has not yet melted remains near the inlet of the first heat exchanger22in early spring and when the surrounding air is cold, and when the duct between the second heat exchanger12and the outlet is installed for a long time in the ceiling space R12so that the air that has passed through the duct can be warmed by the heat of the ceiling space R12.

In this status, the control unit313implements control such that the warm outside air flows to the second heat exchanger12. As a result, defrosting of the second heat exchanger12can be implemented. Note that that the output of the instruction to the actuator for controlling the state of the refrigerant in the refrigerant circuit so as to raise the temperature of the refrigerant flowing into the second heat exchanger12, may be performed by any of the methods described in the above embodiments, and the description thereof will be omitted.

In the present embodiment, the temperature of the second heat exchanger12can be raised to further to improve the defrosting efficiency by allowing air having a higher detected temperature between the air from the living room space R11and the air from the outdoors to flow into the second heat exchanger12.

Eighth Embodiment

A method other than the above embodiments may be used to adjust the air flow to the exhaust unit. Accordingly, in the eighth embodiment, a method for providing a bypass flow path for directly passing air between the air supply unit and the exhaust unit will be described.

FIG.9is a diagram illustrating a configuration example of a ventilation apparatus and an air conditioner according to the eighth embodiment. In the example illustrated inFIG.9, a ventilation apparatus1E and an air conditioner2are provided for air conditioning an indoor space. In the third embodiment, the same reference numerals are assigned to the same configuration as in the above-described embodiment, and descriptions thereof will be omitted.

As illustrated inFIG.9, a bypass flow path P402is provided between the air supply unit20and the exhaust unit410. The bypass flow path P402includes a first bypass partial flow path P402A on the air supply unit20side from the air supply flow path P401, a third bypass partial flow path P402C on the exhaust unit410side from the return air flow path P403, and a second bypass partial flow path P402B connecting the first bypass partial flow path P402A and the third bypass partial flow path P402C.

An opening/closing damper440(an example of a bypass guide mechanism) is provided on the second bypass partial flow path P4102B. The opening/closing damper440is usually closed. The opening/closing damper440can guide the air warmed by the air supply unit20directly to the exhaust unit410by controlling from the control unit413provided in the exhaust unit410through the signal line S401.

After taking in outside air (OA), the air supply unit20usually supplies air (SA) to the living room space R11through the first bypass partial flow path P402A and the air supply flow path P401.

The exhaust unit410includes a fan11, a second heat exchanger12, a control unit413, and a temperature detecting unit14, and takes in return air (RA) of the living room space R11through the return air flow path P403and the third bypass partial flow path P402C, and exhausts air (EA) to the outdoors.

While the second heat exchanger12functions as an evaporator, the control unit413of the exhaust unit410according to the present modified example detects whether a predetermined standard indicating frosting of the second heat exchanger12is satisfied. Note that that the predetermined reference is the same as that of the above-described embodiment, and the description thereof is omitted.

When the control unit413determines that the predetermined standard is satisfied, the control unit413further determines whether the temperature of the air after passing through the first heat exchanger22is higher than the predetermined temperature (may be a preset reference value or the temperature of the air in the living room space R11). The predetermined temperature is determined according to the embodiment. When it is determined that the temperature of the air after passing through the first heat exchanger22is higher than the predetermined temperature, the control unit413implements control to open the opening/closing damper440.

Thus, when it is determined that the second heat exchanger12is frosted, and when it is determined that the temperature of the air that has undergone heat exchange by the first heat exchanger22is higher than the predetermined temperature, the control unit413according to the present modified example implements control to open the opening/closing damper440. As a result, the air warmed in the exhaust unit410can flow directly to the second heat exchanger12through the bypass flow path P402, thereby improving the defrosting efficiency of the second heat exchanger12. Note that that the output of the instruction to the actuator for controlling the state of the refrigerant in the refrigerant circuit so as to raise the temperature of the refrigerant flowing into the second heat exchanger12may be performed by any of the methods described in the above embodiment, and the description thereof will be omitted.

Ninth Embodiment

A method other than the above-described embodiment may be used to adjust the air flow to the exhaust unit. Therefore, in the ninth embodiment, the case of linking with the air conditioner2B will be described.

In the present embodiment, as in the second embodiment, an example including the ventilation apparatus1B, the air conditioner2B and the upper level control device100will be used. The present embodiment has the same configuration as the second embodiment as illustrated inFIG.2.

The control unit113A and the control unit113B control the configuration in the corresponding exhaust unit. Further, the control unit113A and the control unit113B transmit the detection result obtained by the temperature detecting unit14or the like in each exhaust unit to the control unit152of the compressor unit150.

Based on the detection result, the control unit152of the compressor unit150determines whether the second heat exchanger12of the exhaust units110A and110B satisfies a predetermined reference indicating a frosted state.

The control unit152of the compressor unit150transmits the determination result, the recognition result to the upper level control device100. Thus, the upper level control device100can recognize the status of the first exhaust unit110A and the second exhaust unit110B.

The upper level control device100performs various kinds of control in order to link the operation of the ventilation apparatus1B with the operation of the air conditioner2B.

For example, when the upper level control device100recognizes that at least one of the second heat exchangers12of the first exhaust unit110A and the second exhaust unit110B is frosted, the upper level control device100outputs a control signal to raise the temperature currently set in the air conditioner2B, to the air conditioner2B provided in the living room space R11.

The air conditioner2B improves the heating capability according to the control signal. As a result, the temperature of the air in the living room space R11rises. Therefore, the temperature of the air flowing into the second heat exchanger12can be raised. Therefore, the defrosting efficiency of the second heat exchanger12can be increased.

Further, when a plurality of air-conditioning indoor units exist, the upper level control device100may select an air-conditioning indoor unit that improves heating capability according to the arrangement of the air-conditioning indoor units. In the example illustrated inFIG.2, the upper level control device100may improve the heating capability of the air-conditioning indoor unit81provided near the ventilation port91A of the exhaust unit110A when the second heat exchanger12of the exhaust unit110A is frosted, and may improve the heating capability of the air-conditioning indoor unit82provided near the ventilation port91B of the exhaust unit110B when the second heat exchanger12of the exhaust unit110B is frosted. Note that that the output of the instruction to the actuator for controlling the state of the refrigerant in the refrigerant circuit so as to raise the temperature of the refrigerant flowing into the second heat exchanger12may be performed by any of the methods described in the above embodiment, and the description thereof will be omitted.

That is, when the temperature of the refrigerant in the refrigerant circuit described in the above embodiment is controlled to rise, the comfort of the living room space R11can be maintained by improving the heating capability of the air conditioner2B even when the ability of the ventilation apparatus1B to adjust the temperature decreases.

Tenth Embodiment

A method other than the above embodiment may be used to adjust the air flow to the exhaust unit.

In the present embodiment, as in the second embodiment, the example includes a ventilation apparatus1B, an air conditioner2B, and an upper level control device100. The present embodiment has the same configuration as the second embodiment as illustrated inFIG.2.

As in the above embodiment, the upper level control device100can recognize the status of the first exhaust unit110A and the second exhaust unit110B from the determination result from the control unit152of the compressor unit150.

When the upper level control device100recognizes that at least one of the second heat exchangers12of the first exhaust unit110A and the second exhaust unit110B is frosted, the upper level control device100outputs a control signal for raising the air volume of the fan11to the exhaust unit (for example, the first exhaust unit110A or the second exhaust unit110B) including the frosted second heat exchanger12.

Thus, in the present embodiment, the upper level control device100controls the fan11corresponding to the second heat exchanger12based on the respective statuses of the plurality of second heat exchangers12to adjust the air volume of air flowing to the second heat exchanger12.

As a result, the air volume flowing into the second heat exchanger12that is frosted is raised, so that defrosting of the second heat exchanger12can be implemented. That is, in the present embodiment, the efficiency of heat exchange is increased by increasing the air volume on the exhaust heat recovery machine side, and a decrease in the temperature of the refrigerant flowing through the second heat exchanger12is prevented to implement defrosting.

In the present embodiment, even when there are multiple second heat exchangers12, by adjusting the air volume flowing through the second heat exchanger12in accordance with each status of the second heat exchanger12, defrosting can be achieved in accordance with the degree of defrosting of the second heat exchanger12while maintaining the comfort of the indoor space.

Modified Example 1 of the Tenth Embodiment

In the present modified example, an example will be described in which the control is different according to the degree of frosting of the plurality of second heat exchangers12when the plurality of second heat exchangers12are frosted. Note that that the modified example 1 of the tenth embodiment has the same configuration as the tenth embodiment.

When the upper level control device100of the present modified example recognizes that the second heat exchangers12are frosting, the upper level control device100acquires the frosting level of each of the second heat exchangers12. The frosting level is, for example, a value at which the degree of frosting of the second heat exchanger12is set based on the determination result by the control unit152of the compressor unit150, and is set according to the time after frosting and the current temperature of the refrigerant.

When it is determined that the frosting level (degree of frosting) of one of the second heat exchangers12is greater than that of the other second heat exchanger12among the plurality of second heat exchangers12, the upper level control device100implements control to increase the air volume (an example of the first air volume) of the fan11corresponding to one of the second heat exchangers12compared with the air volume (an example of the second air volume) of the fan11corresponding to the other second heat exchanger12.

Further, when the upper level control device100implements control to increase the air volume of the fan11corresponding to one of the second heat exchangers12, the upper level control device100may control to decrease the air volume of the fan11corresponding to the other second heat exchanger12compared with before the control to increase the air volume. As a result, the total value of the air discharge amount is maintained, and, therefore, the negative pressure of the living room space R11can be prevented.

After defrosting of one second heat exchanger12is completed, the upper level control device100implements control to increase the air volume of the fan11corresponding to the other second heat exchanger12and to decrease the air volume of the fan11corresponding to the one second heat exchanger12.

In the present embodiment, the defrosting of for the second heat exchanger12with a high degree of frosting among the plurality of second heat exchangers12can be prioritized, so that the defrosting efficiency can be improved.

Modified Example 2 of Tenth Embodiment

Therefore, the case in which the air volume taken in from the outdoors by the air supply unit group is increased when the air volume exhausted from the exhaust unit group is increased will be described in the modified example 2. Note that that the modified example 2 of the tenth embodiment has the same configuration as the tenth embodiment.

As in the tenth embodiment, the control unit152of the compressor unit150of the present modified example determines whether the second heat exchanger12of the first exhaust unit110A and the second exhaust unit110B satisfies a predetermined reference indicating frosting based on the received outside air temperature.

When the control unit152of the compressor unit150determines that any one or more of the first exhaust unit110A and the second exhaust unit110B satisfies the predetermined reference, the upper level control device100instructs the exhaust unit to increase the air volume. The method of the instruction is the same as that of the tenth embodiment, and the description thereof is omitted.

The upper level control device100according to the present modified example instructs an increase in the air quantity (air volume) supplied to one or more of the first air supply unit120A and the second air supply unit120B instead of instructing a decrease in the air quantity as described in the modified example 1 of the tenth embodiment. The instruction of the increase is given from the upper level control device100to the control unit123of the first air supply unit120A and the second air supply unit120B through the control unit152of the compressor unit150.

The target for instructing the increase of the air quantity (air volume) supplied may be any one of the first air supply unit120A and the second air supply unit120B, or may be each of the first air supply unit120A and the second air supply unit120B. However, the upper level control device100makes an adjustment such that the air volume discharged by the first exhaust unit110A and the second exhaust unit110B and the air volume taken in by the first air supply unit120A and the second air supply unit120B are the same.

In this way, when the control to increase the air volume flowing to the second heat exchanger12is performed on the fan11associated with any one of the plurality of second heat exchangers12included in the exhaust unit group, the upper level control device100according to the present modified example controls the fan21included in the air supply unit group to increase the air volume flowing to the first heat exchanger22, compared with before the predetermined standard is satisfied, based on the increased air volume. As a result, in the present modified example, the air volume taken in and the air volume exhausted are approximately the same, and, therefore, it is possible to prevent negative pressure in the living room space R11.

Eleventh Embodiment

The linking between the air conditioner and the ventilation apparatus is not limited to the control described above. Therefore, in the eleventh embodiment, a case where the air conditioner starts a defrosting operation will be described. Note that that the configuration of the eleventh embodiment is similar to that of the second embodiment.

The upper level control device100receives the status of the air conditioner2B from the control unit171of the outdoor unit170and receives the status of the ventilation apparatus1B from the control unit152of the compressor unit150. The upper level control device100performs various kinds of control according to the status of the air conditioner2B and the status of the ventilation apparatus1B.

For example, when the upper level control device100recognizes that the air conditioner2B is performing the defrosting operation based on the information received from the control unit171of the outdoor unit170, the upper level control device100performs control to improve the heating capability of the ventilation apparatus1B.

That is, when the air conditioner2B performs a defrosting operation, the air conditioner2B does not function as a heater, and the temperature in the living room space R11may decrease. On the other hand, when the air supply temperature of the first air supply unit120A and the second air supply unit120B is increased to compensate for the degrading of the function of the air conditioner2B when the air conditioner2B performs a defrosting operation, the temperature of the refrigerant flowing to the second heat exchanger12of the first exhaust unit110A and the second exhaust unit110B connected by the refrigerant circuits F101, F102, F103, and F104decreases. In this case, the possibility of frosting of the second heat exchanger12of the first exhaust unit110A and the second exhaust unit110B increases.

Therefore, when the upper level control device100receives a signal indicating that defrosting operation is being performed from the air conditioner2B, the upper level control device controls the air supply units120A and120B to increase the air volume due to the air supply from the first air supply flow path P101and the second air supply flow path P102to the living room space R11as compared with that before receiving a signal indicating that a defrosting operation will be performed from the air conditioner2B, and controls the exhaust units110A and110B to increase the air volume due to the air exhaust from the first exhaust flow path P103and the second exhaust flow path P104to the outdoors as compared with that before receiving a signal indicating that defrosting operation will be performed from the air conditioner2B.

In the present embodiment, when the air conditioner2B is performing a defrosting operation, the upper level control device100increases the air volume of the air supply and exhausted air of the ventilation apparatus1B without increasing the air supply temperature with respect to the ventilation apparatus1B, thereby improving the heating capability and preventing the decrease of the temperature in the living room space R11.

Twelfth Embodiment

In the above-described embodiment, an example in which the upper level control device100controls one compressor unit150has been described. However, the number of compressor units controlled by the upper level control device100is not limited to one. Accordingly, in the twelfth embodiment, an example in which the upper level control device100controls a plurality of ventilation apparatuses and a plurality of air conditioners will be described.

FIG.10is a diagram illustrating an arrangement of a group of devices including the upper level control device500according to the twelfth embodiment. The example illustrated inFIG.10includes at least living room spaces R501, R502, R503, lavatory rooms R511, R512, and a pipe shaft R521.

The lavatory rooms R511, R512are provided with ventilation ports595A,595B, respectively.

The air conditioner2F includes three outdoor units571,572, and573. The outdoor unit571is connected to the four air-conditioning indoor units581,582,583, and584by a connection pipe (not illustrated). The outdoor unit572is connected to the two air-conditioning indoor units585and586by a connection pipe (not illustrated). The outdoor unit573is connected to two air-conditioning indoor units587and588by a connection pipe (not illustrated).

The three outdoor units571to573are connected to the upper level control device500by a signal line. Thus, the three outdoor units571to573can perform air conditioning control according to the control of the upper level control device500.

The first ventilation apparatus1F_1is a ventilation apparatus provided in the living room space R501and includes a first compressor unit550A, a first air supply unit520A, and a first exhaust unit510A.

The first air supply unit520A supplies air (SA) from the ventilation port592A. The first exhaust unit510A returns air (RA) from the ventilation port591A. The first compressor unit550A, the first air supply unit520A, and the first exhaust unit510A are connected by a connection pipe F501. The connection pipe F501includes a plurality of refrigerant connection pipes. Thereby, the refrigerant can be circulated between the first compressor unit550A, the first air supply unit520A, and the first exhaust unit510A.

The first compressor unit550A, the first air supply unit520A, and the first exhaust unit510A are connected by a signal line (not illustrated). This enables transmission and reception of information between the units. The configuration inside the first compressor unit550A, the first air supply unit520A, and the first exhaust unit510A is the same as that of the compressor unit150, the first air supply unit120A, and the first exhaust unit110A illustrated inFIG.2, and the description thereof will be omitted.

The second ventilation apparatus1F_2is a ventilation apparatus provided in the living room space R502and includes a second compressor unit550B, a second air supply unit520B, and a second exhaust unit510B.

The second air supply unit520B supplies air (SA) from the ventilation port592B. The second exhaust unit510B returns air (RA) from the ventilation port591B. The second compressor unit550B, the second air supply unit520B, and the second exhaust unit510B are connected by a connection pipe F502. The connection pipe F502includes a plurality of refrigerant connection pipes. Thus, the refrigerant can be circulated between the second compressor unit550B, the second air supply unit520B, and the second exhaust unit510B.

The second compressor unit550B, the second air supply unit520B, and the second exhaust unit510B are connected by a signal line (not illustrated). This enables transmission and reception of information between the units. The configuration inside the second compressor unit550B, the second air supply unit520B, and the second exhaust unit510B is the same as that of the compressor unit150, the first air supply unit120A, and the first exhaust unit110A illustrated inFIG.2, and descriptions thereof will be omitted.

The third ventilation apparatus1F_3is a ventilation apparatus provided in the living room space R503and includes a third compressor unit550C, a third air supply unit520C, and a third exhaust unit510C.

The third air supply unit520C supplies air (SA) from the ventilation port592C. The third exhaust unit510C returns air (RA) from the ventilation port591C. The third compressor unit550C, the third air supply unit520C, and the third exhaust unit510C are connected by a connection pipe F503. The connection pipe F503includes a plurality of refrigerant connection pipes. Thus, the refrigerant can be circulated between the third compressor unit550C, the third air supply unit520C, and the third exhaust unit510C.

The third compressor unit550C, the third air supply unit520C, and the third exhaust unit510C are connected by a signal line (not illustrated). This enables transmission and reception of information between the units. The configuration inside the third compressor unit550C, the third air supply unit520C, and the third exhaust unit510C is the same as that of the compressor unit150, the first air supply unit120A, and the first exhaust unit110A illustrated inFIG.2, and the description thereof will be omitted.

As described above, the present embodiment includes a plurality of combinations of a compressor unit, an air supply unit, an exhaust unit, and a connection pipe. The first compressor unit550A, the second compressor unit550B, and the third compressor unit550C are arranged on the pipe shaft R521.

The upper level control device500is connected to the first compressor unit550A, the second compressor unit550B, and the third compressor unit550C by a signal line. Accordingly, the upper level control device500can recognize the state of each apparatus of the first ventilation apparatus1F_1to the third ventilation apparatus1F_3and control each apparatus.

According to the above configuration, while the second heat exchanger12of each of the first exhaust units510A to the third exhaust unit510C functions as an evaporator, the control unit (not illustrated) of the first compressor unit550A to the third compressor unit550C receives the temperature of the refrigerant flowing through the second heat exchanger12from each of the first exhaust units510A to the third exhaust unit510C.

Then, while the second heat exchanger12functions as an evaporator, the control unit of the first compressor unit550A to the third compressor unit550C of the present embodiment determines whether a predetermined reference indicating the frosting in the second heat exchanger12is satisfied based on the temperature of the refrigerant in the second heat exchanger12. The predetermined reference is the same as in the above-described embodiment, and, therefore, the description thereof will be omitted.

When the upper level control device500determines that the predetermined standard is satisfied, the upper level control device500raises the room temperature of the air conditioner2F corresponding to the region (same zone) where the exhaust unit including the frosted second heat exchanger12is provided.

For example, when it is determined that the frosted second heat exchanger12of the exhaust unit510C is frosted, the set temperature of the air conditioner2F provided in the same living room space R503is raised. In particular, by raising the set temperature of the air-conditioning indoor unit582provided in the vicinity of the ventilation port591C of the exhaust unit510C, the defrosting efficiency of the second heat exchanger12of the exhaust unit510C can be increased.

Further, the capability of the ventilation apparatus can be decreased corresponding to the increase in the capability of the air conditioner2F. That is, because the temperature of the refrigerant passing through the exhaust unit of the air conditioner can be increased, rapid defrosting of the heat exchanger can be implemented. The method for increasing the temperature of the refrigerant passing through the exhaust unit of the ventilation apparatus is the same as the above embodiment, and the description thereof is omitted.

Further, the upper level control device500may use any of the methods described in the embodiment described above for outputting an instruction to the actuator for controlling the state of the refrigerant in the refrigerant circuit so as to raise the temperature of the refrigerant flowing into the second heat exchanger12of the exhaust unit510C. For example, as illustrated in the fifth embodiment, the temperature of the refrigerant flowing into the second heat exchanger12may be raised by controlling the flow of the refrigerant circuit including the second heat exchanger12of the exhaust unit510C to reverse cycle. Further, the temperature of the refrigerant flowing into the second heat exchanger12may be increased by controlling the flow of the refrigerant circuit including the second heat exchanger12of the exhaust unit510C while maintaining the forward cycle.

For example, in the upper level control device500according to the present embodiment, as the defrosting of the second heat exchanger12of the exhaust unit510C of the ventilation apparatus1F_3, the air volume exhausted from the exhaust unit510C may be controlled to be increased compared with that before the defrosting operation of the air conditioner2F is started. In this case, the upper level control device500may perform control to decrease the air volume exhausted from the exhaust unit510A of the ventilation apparatus1F_1and the air volume exhausted from the exhaust unit510B of the ventilation apparatus1F_2, which have different systems from the ventilation apparatus1F_3. The control to increase the air volume and the control to decrease the air volume are the same as that in the above-described embodiment, and will not be described. The control can implement defrosting of the second heat exchanger12of the exhaust unit510C and prevent negative pressure in the living room spaces R501, R502and R503by maintaining the air volume discharged.

In the present embodiment, the temperature of the air flowing to the second heat exchanger12is increased by increasing the temperature of the living room space, thereby increasing the defrosting efficiency.

In the present embodiment, when the defrosting operation of the ventilation apparatuses1F_1to1F_3is performed, the heating capability of the air conditioner provided in the same area as the ventilation apparatuses1F_1to1F_3is improved to compensate for the decrease in the heating capability of the ventilation apparatus, thereby maintaining comfort.

Modified Example 1 of the Twelfth Embodiment

In the modified example 1 of the twelfth embodiment, a case where the air conditioner2F starts the defrosting operation will be described. In the embodiment described above, when the second heat exchanger12is determined to be in a frosted state, an example of outputting a predetermined instruction to the actuator that controls the state of the refrigerant in the refrigerant circuit has been described. On the other hand, in a modified example of the present embodiment, even when the frosted state is determined, the output of the predetermined instruction is prevented when a predetermined condition is satisfied.

After receiving a signal indicating that defrosting operation is to be performed from the air conditioner2F, the upper level control device500receives a determination result that the second heat exchanger12is determined to be in the frosted state from the control units of the first compressor unit550A to the third compressor unit550C.

In this case, while the air conditioner2F is performing the defrosting operation, the upper level control device500prevents output of a predetermined instruction to the actuator for controlling the state of the refrigerant in the refrigerant circuit in order to raise the temperature of the refrigerant flowing through the frosted second heat exchanger12.

Further, while the air conditioner2F is performing the defrosting operation, the upper level control device500may perform control for increasing the air volume of the fan11corresponding to the frosted second heat exchanger12.

Modified Example 2 of the Twelfth Embodiment

As a further modified example, the upper level control device500may send an instruction to the compressor unit (for example, the compressor unit550C) to reduce the flow rate of refrigerant to the second heat exchanger12determined to be likely to be frosted while the air conditioner2F is performing a defrosting operation. In this way, the progress of frosting can be prevented. That is, by preventing the progress of frosting of the second heat exchanger12, the simultaneous defrosting operation with the air conditioner2F in which the defrosting operation is currently performed can be prevented.

As a result, the heating capability of the first heat exchanger22of the air supply unit (for example, the air supply unit520C) can be prevented from being stopped, so that a minimum level of comfort can be maintained.

As the reference for determining the possibility of frosting, for example, the surface temperature of the second heat exchanger12and the temperature of the indoor air in the living room space (for example, the living room space R505) are measured, and the surface temperature of the second heat exchanger12is lower than the dew point temperature of the air, and the surface temperature of the second heat exchanger12is 0° C. or less. As the temperature of the indoor air, for example, the temperature measured by a sensor provided near the ventilation port is used.

Further, the upper level control device500may monitor the frosted state of the second heat exchangers12of the plurality of exhaust units and the frosted state of the plurality of air conditioners2F, and perform defrosting operations sequentially from the devices determined to be likely to be frosted, thereby shortening the time for defrosting operations of the plurality of devices at the same time or preventing defrosting operations of the plurality of devices at the same time.

Modified Example 3 of Twelfth Embodiment

Similar to the modified example 1 of twelfth embodiment, the upper level control device500of the modified example 3 of the twelfth embodiment receives a signal indicating that defrosting operation is to be performed from the air conditioner2F, and then receives a determination result that the second heat exchanger12is determined to be in a frosted state from the control units of the first compressor unit550A to the third compressor unit550C.

In this case, while the air conditioner2F is performing the defrosting operation, the upper level control device500prevents output of a predetermined instruction to the actuator for controlling the state of the refrigerant in the refrigerant circuit in order to raise the temperature of the refrigerant flowing through the frosted second heat exchanger12.

Further, when the upper level control device500receives a signal from the air conditioner2F to perform a defrosting operation, the upper level control device500controls the air supply unit (for example, the air supply unit520C) to increase the air volume due to the air supply from the air supply flow path to the living room space (for example, the living room space R503) as compared with that before the air conditioner2F performs defrosting operation, and controls the exhaust unit (for example, the exhaust unit510C) to increase the air volume due to the exhaust air from the second air flow path to the outdoors as compared with that before the air conditioner2F performs defrosting operation.

In the present modified example, the air volume of the air supply and the air volume of the exhaust air are maintained in total, and, therefore, it is possible to prevent negative pressure in the living room space. Further, by increasing the air volume of the ventilation apparatus, it is possible to prevent a decrease of the heating capability.

Modified Example 4 of Twelfth Embodiment

Further, control may be performed to prevent simultaneous defrosting of the air conditioner2F and the ventilation apparatus.

When it is determined that the second heat exchanger12of the exhaust unit is frosted, the upper level control device500of the present modified example starts defrosting control of the second heat exchanger12. The defrosting method may be any of the methods described in the above embodiment.

Further, when the defrosting control of the second heat exchanger12is started, the upper level control device500transmits a control signal to the air conditioner2F instructing not to perform a defrosting operation.

In the present modified example, it is possible to prevent the air conditioner2F and the ventilation apparatus from simultaneously performing the defrosting operation. By preventing the simultaneous defrosting, it is possible to prevent the degrading of the air conditioning capability.

Thirteenth Embodiment

Further, when a plurality of ventilation apparatuses are provided, when the second heat exchangers12of the plurality of ventilation apparatuses are frosted, defrosting control may be different according to the degree of frosting of the second heat exchangers12of the plurality of ventilation apparatuses.

In the present embodiment, an example in which the upper level control device500controls four ventilation apparatuses will be described. The number of the air conditioners2F that the upper level control device500controls may be any number.

FIG.11is a flowchart illustrating a processing procedure performed by the upper level control device500according to the present embodiment. Although an example of processing performed by the upper level control device500will be described in the present embodiment, the processing is not limited to the upper level control device500and may be performed on a centralized management server provided at a remote location or a cloud.

The upper level control device500acquires a detection result obtained by the temperature detecting unit14from each of the plurality of ventilation apparatuses (S2201).

Based on the detection result, the upper level control device500identifies the number of exhaust units (of the second heat exchanger12) including the second heat exchanger12that is frosted (S2202). For example, it may be determined that four exhaust units are frosted.

Then, the upper level control device500determines whether the detection result of the exhaust unit that is frosted is less than or equal to the first determination logic (S2203). The first determination logic is to determine, for example, whether the evaporation temperature t of the refrigerant flowing through the second heat exchanger12of the exhaust unit is lower than a predetermined value x1, or whether the pressure p of the refrigerant flowing through the second heat exchanger12of the exhaust unit is lower than a predetermined value y1. Further determination methods may be used as the determination logic. For example, as another example, it may be determined whether the surface temperature t2 of the second heat exchanger12is lower than a predetermined value z1, an imaging means may capture the surface of the second heat exchanger12, calculate the matching degree between the captured image data and the normal image data, and determine whether the difference is greater than w %.

When the upper level control device500determines that the detection result is less than or equal to the first determination logic (S2203: Yes), the upper level control device500determines that the exhaust unit is at frosting level1(S2204).

On the other hand, when the upper level control device500determines that the detection result is greater than the first determination logic (S2203: No), the upper level control device500determines whether the detection result of the exhaust unit that is frosted is less than or equal to the second determination logic (S2205). The second determination logic is to determine, for example, whether the evaporation temperature t of the refrigerant flowing through the second heat exchanger12of the exhaust unit is less than a predetermined value x2 or whether the pressure p of the refrigerant flowing through the second heat exchanger12of the exhaust unit is less than a predetermined value y2. The predetermined value x1<a predetermined value x2 and the predetermined value y1<a predetermined value y2.

When the upper level control device500determines that the detection result is less than or equal to the second determination logic (S2205: Yes), the upper level control device determines that the exhaust unit is frosting level2(S2206).

On the other hand, when the upper level control device500determines that the detection result is greater than the first determination logic (S2205: No), the upper level control device determines that the exhaust unit is frosting level3(S2207).

Thereafter, the upper level control device500determines whether the frosting level has been set for all the exhaust units that are frosted (S2208). If it is determined that the frosting level has not been set for all of the exhaust units (S2208: No), processing is performed from S2203.

On the other hand, when it is determined that the frosting level has been set for all exhaust units that are frosted (S2208: YES), the upper level control device500calculates the time required for the frosting operation for each exhaust unit (S2209). Any method may be used for calculating the time required for the frosting operation including a well-known method. The time required for a frosting operation may be predetermined for each frosting level.

Further, the upper level control device500calculates an index of required comfort in the living room space based on the current status of the living room space (S2210). The current status of the living room space is, for example, the detection result of a sensor provided near the ventilation port of the living room space. The index of required comfort is the index of required comfort in the current living room space. The index of comfort is determined according to, for example, the required value of the temperature blowing out from the ventilation opening, the air volume required for ventilation, and the number of people present in the current living room space. The higher the index of comfort, the more comfortable the living room space needs to be maintained.

The upper level control device500determines whether the calculated index of required comfort is greater than the reference value k (S2211).

When it is determined that the calculated index of required comfort is greater than the reference value k (S2211: Yes), the upper level control device500makes a setting to sequentially perform a defrosting operation for the plurality of exhaust units (S2212). That is, the upper level control device500prevents simultaneous defrosting operations by the setting of sequentially performing defrosting operations to maintain the comfort of the living room space. The order of defrosting is set according to the defrosting level. For example, when there is one exhaust unit having the frosting level1, two exhaust units having the frosting level2, and one exhaust unit having the frosting level3, defrosting is set to be performed in the order of one of the exhaust units having the frosting level1, one of the exhaust units having the frosting level2, the other one of the exhaust units having the frosting level2, and the exhaust unit having the frosting level3.

On the other hand, when the upper level control device500determines that the calculated index of required comfort is less than or equal to the reference value k (S2211: No), defrosting is set to be performed simultaneously for the plurality of exhaust units (S2213). That is, the upper level control device500ends the defrosting operations quickly by setting to perform simultaneous defrosting operations. Note that defrosting operations are not performed for all of the exhaust units. The order of the defrosting operations may be set according to the defrosting level. For example, when there is one exhaust unit having the frosting level1, two exhaust units having the frosting level2, and one exhaust unit having the frosting level3, a setting is made to simultaneously perform the defrosting operation of the exhaust unit having the frosting level1and the exhaust unit having the frosting level3, and then to simultaneously perform the defrosting operations of the two exhaust units having the frosting level2. This setting allows for a balance between the load on the living room space and the end of the defrosting operation.

The upper level control device500outputs the defrosting operation instruction for each exhaust unit according to the setting (S2214).

Thus, the upper level control device500according to the present embodiment acquires the defrosted state of the second heat exchangers12, generates a plurality of patterns for performing the defrosting operation of the plurality of second heat exchangers12when it is determined that the plurality of second heat exchangers12are defrosted while the plurality of second heat exchangers12function as evaporators, and performs defrosting control by using any one of the plurality of generated patterns based on the defrosted state of the plurality of second heat exchangers and the current status of the living room space.

In the present embodiment, the defrosting operation is performed sequentially according to the defrosting level of the exhaust unit. At that time, when comfort is required, comfort can be maintained by controlling such that the defrosting operations of a plurality of exhaust units are not performed simultaneously.

Further, when comfort is not important, temperature control of the plurality of ventilation apparatuses is stopped at the same time, and the defrosting operation is performed simultaneously by the exhaust unit of the plurality of ventilation apparatuses. Since temperature control is stopped, comfort is reduced, but the defrosting operation can be performed in a short period.

In the above-described embodiments and modified examples, an example in which the air supply unit is a casing (an example of the first casing) that houses the first heat exchanger22and at least a part of the air flow path (an example of the first air flow path), and the exhaust unit is a casing (an example of the second casing) that houses the second heat exchanger12and at least a part of the air flow path (an example of the second air flow path), and the casings are separated has been described.

Thus, the exhaust unit and the air supply unit can be arranged at different positions. Thus, the degree of freedom of the arrangement of the ventilation apparatus capable of recovering heat can be increased compared with the conventional ventilation apparatus.

However, the above-described embodiments and modified examples are not limited to the example where the casing of the air supply unit and the casing of the exhaust unit are separated, and the air supply unit and the exhaust unit may be integrated. That is, when the first heat exchanger22and the second heat exchanger12are connected by a refrigerant circuit, and a fan21corresponding to the first heat exchanger22and a fan corresponding to the second heat exchanger12are provided, the air volume adjustment and the temperature adjustment of the refrigerant can be applied as described in the above-described embodiments and modified examples. As described above, the method described in the above-described embodiments and modified examples may be applied when the air supply unit and the exhaust unit are integrated.

The above-described embodiments and modified examples describe the defrosting method. The method described in the above-described embodiments and modified examples is not limited to the use of the defrosting method alone, but may be used in combination with one or more defrosting methods described in other embodiments and modified examples.

Although the embodiments have been described above, it will be understood that various changes in form and details are possible without departing from the object and scope of the claims. Various variations and improvements such as combinations and substitutions with some or all of the other embodiments are possible.

The present international application is based upon and claims priority to Japanese patent application no. 2021-205605 filed on Dec. 17, 2021, the entire contents of which are incorporated herein by reference.

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