Air Conditioning Device

This application is a Continuation application of PCT Application No. PCT/JP2024/003666, filed Feb. 5, 2024 and based upon and claiming the benefit of priority from Japanese Patent Application No. 2023-024988, filed Feb. 21, 2023, the entire contents of all which are incorporated herein by reference.

Embodiments described herein relate generally to an air conditioning device.

In conventional air conditioning devices using a refrigeration cycle (heat pump cycle), an outdoor unit including a compressor, a four-way valve, and an outdoor heat exchanger, and a flow control device such as an expansion valve, and an indoor unit including an indoor heat exchanger, are connected by refrigerant pipes, constituting a refrigerant circuit that circulates the refrigerant. An air conditioning device performs cooling by absorbing heat from the air when the refrigerant evaporates in the indoor heat exchanger, and performs heating by radiating heat to the air when the refrigerant condenses.

For example, in a case where an air conditioning device comprises a plurality of indoor units, there is an air conditioning device capable of performing simultaneous cooling and heating operation (mixed cooling and heating operation) that can determine whether heating or cooling is appropriate in accordance with the set temperature on a remote controller provided for each indoor unit and the temperature around the indoor unit, and can perform either cooling or heating for each indoor unit.

In addition, in the simultaneous cooling and heating operation, a heat recovery operation is performed among a plurality of indoor units. When the air conditioning load rates for cooling and heating are substantially equivalent, the comfort and energy efficiency of the air conditioning device are improved by reducing the amount of heat exchange in the outdoor unit. In addition, by adjusting the flow rate of the refrigerant to the outdoor heat exchanger in accordance with the respective capacities of a cooling operation and a heating operation, the amount of heat exchange in the outdoor unit can be controlled, and the operation with improved comfort and energy efficiency can be performed.

However, when the outdoor unit is mainly operated for heating during the simultaneous heating and cooling operation when the outdoor temperature is low, the outdoor heat exchanger becomes a low outdoor temperature evaporator, and the indoor heat exchanger of the indoor unit in cooling operation becomes a room temperature evaporator. For this reason, the evaporation temperature becomes a temperature closer to the outdoor temperature, and the difference between the evaporation temperature and the indoor temperature becomes larger in the indoor unit, resulting in a higher degree of superheat. In general, since the energy efficiency of the air conditioning device is improved as the degree of superheat is smaller, the target degree of superheat is set to a small value. In contrast, if the target degree of superheat is small, for example, the opening of the expansion valve may become too large. For this reason, the outdoor temperature (outdoor air temperature) may become lower than the evaporation temperature, due to insufficient pressure reduction on the low-pressure side, and the refrigerant may accumulate in the outdoor heat exchanger, a low-pressure receiver, or the like, and the liquid pressure of the refrigerant flowing through a liquid pipe (liquid pipe pressure) may decrease. The similar decrease in liquid pressure may also occur when the outdoor unit is mainly operated for cooling and the outdoor heat exchanger becomes a condenser.

The present invention has been accomplished based on this, and aims to provide an air conditioning device capable of appropriately suppressing the decrease in liquid pipe pressure during simultaneous cooling and heating operation.

In general, according to one embodiment, an air conditioning device comprises an outdoor unit, a plurality of indoor units, a plurality of switching units, and a control unit.

The outdoor unit includes a compressor, an outdoor heat exchanger, an outdoor blower, an outdoor expansion valve, and an outdoor temperature detection unit. The compressor sucks, compresses, and discharges a refrigerant. The outdoor heat exchanger functions as an evaporator or a condenser which exchanges heat between the outdoor air and the refrigerant. The outdoor blower sucks the outdoor air and blows the air which is subjected to heat exchange in the outdoor heat exchanger to the outside. The outdoor expansion valve adjusts the flow rate of the refrigerant flowing through the outdoor heat exchanger in accordance with its opening. The outdoor temperature detection unit detects the outdoor temperature, which is the temperature of the outdoor air.

The indoor unit includes an indoor heat exchanger, an indoor blower, an indoor expansion valve, and an indoor temperature detection unit. The indoor heat exchanger functions as a condenser or evaporator which exchanges heat between indoor air and the refrigerant. The indoor blower sucks the indoor air and blows out the air which is subjected to heat exchange in the indoor heat exchanger into the room. The indoor expansion valve adjusts the flow rate of the refrigerant flowing through the indoor heat exchanger in accordance with its opening. The indoor temperature detection unit detects the indoor temperature, which is the temperature of the indoor air.

The switching unit switches the flow of the refrigerant between the outdoor unit and each of the indoor units to one of two flow paths for cooling and heating.

The control unit controls the operations of the outdoor unit, the plurality of indoor units, and the plurality of switching units, and switches each of the plurality of indoor units between cooling and heating. When the outdoor heat exchanger functions as an evaporator and when the indoor units which are in cooling operation and the indoor units which are in heating operation, among the plurality of indoor units, exist, the control unit adjusts the opening of the indoor expansion valve of the indoor unit in cooling operation in accordance with the outdoor temperature and the indoor temperature detected by the indoor temperature detection unit of the indoor unit in heating operation.

An embodiment of the present will be described hereinafter with reference to the accompanying drawings.

is a circuit diagram schematically showing the air conditioning device according to the embodiment. As shown in, the air conditioning devicecomprises an outdoor unitand a plurality of indoor unitsconnected by flow paths through which a refrigerant flows.shows a configuration example in which three indoor units(,, and) are connected to one outdoor unit, but the number of indoor unitsis not limited to this. The flow path is configured to be connected to a plurality of pipes. These pipes include a pipe (hereinafter referred to as an outdoor side pipe)that constitutes the flow path on the outdoor unitside, and a pipe (hereinafter referred to as an indoor side pipe)that constitutes the flow path of the indoor unit.

In addition, the air conditioning devicealso includes multiple switching unitsthat switch the flow of refrigerant between the outdoor unitand each of the multiple indoor unitsto one of two flow paths, cooling or heating. Each of the plurality of switching unitsis provided for each of the plurality of indoor units. In the example shown in, a configuration example in which three switching units(,, and) are provided one for each of the three indoor units. The number of switching unitsneeds only to match the number of indoor units. Thus, a predetermined switching unitis linked to each of the plurality of indoor units.

By comprising these switching units, the air conditioning devicecan perform simultaneous cooling and heating operation (mixed cooling and heating operation). The simultaneous cooling and heating operation is an operating mode of the air conditioning devicein which each of the plurality of indoor unitscan optionally select the cooling operation or the heating operation and perform the operation. During the simultaneous cooling and heating operation, the air conditioning deviceis in the operation mode of either a main cooling operation in which the outdoor unitperforms the cooling operation or a main heating operation in which the outdoor unitperforms the heating operation.

In the following descriptions, it is assumed that the air conditioning deviceis in the operation mode of the main heating operation, that the outdoor unitperforms the heating operation, and that the indoor unitwhich is in cooling operation and the indoor unitwhich is in heating operation exist (exist together), unless otherwise specified in relation to the simultaneous cooling and heating operation. When the indoor unitis in cooling operation, this means that the indoor unitis in a state of actually performing the cooling operation at that time (hereinafter referred to as a cooling operation thermo-on state). When the indoor unitis in heating operation, this means that the indoor unitis in a state of actually performing the heating operation at that time (hereinafter referred to as a heating operation thermo-on state).

States other than the two states of cooling operation and heating operation include a state in which the indoor unitis stopped (operation is ended), a thermo-off state in the cooling operation (hereinafter referred to as a cooling operation thermo-off state), and a thermo-off state in the heating operation (hereinafter referred to as a heating operation thermo-off state). The thermo-off state is, for example, a state in which the indoor temperature has reached the cooling set temperature and the cooling operation is temporarily stopped, or a state in which the indoor temperature has reached the heating set temperature and the heating operation is temporarily stopped.

In addition, the air conditioning devicecomprises a control unitthat controls the operations of the outdoor unit, the plurality of indoor units, and the plurality of switching units, and that switches each of the plurality of indoor unitsto either the cooling operation or the heating operation.

The outdoor unitincludes as its main components a compressor, an outdoor heat exchanger, an outdoor blower, an outdoor expansion valve, an outdoor temperature detection unit, and the like.

The compressorsucks refrigerant from a suction pipe, compresses the refrigerant, and discharges the compressed refrigerant to a discharge pipe. Each of the suction pipeand the discharge pipeconstitutes a part of the outdoor side pipe. For example, the compressoris configured with a sealed container, a rotation shaft, a compression mechanism, an electric mechanism, and the like, and discharges a high-temperature and high-pressure gas-phase refrigerant to the discharge pipe

The outdoor heat exchangerexchanges heat between the outdoor air and the refrigerant. As described above, it is assumed in the present embodiment that the air conditioning deviceis simultaneously operated for cooling and heating during mainly performing the heating operation. For this reason, the outdoor heat exchangerfunctions as an evaporator, and evaporates the liquid phase refrigerant, the gas-liquid two-phase refrigerant, or the like, which is heat exchanged in the indoor heat exchanger(indoor unitin the example shown in) of the indoor unitin the heating operation thermo-on state by heat exchange with the air, and changes the refrigerant into a low-temperature and low-pressure gas phase refrigerant or a gas-liquid two-phase refrigerant. However, when the air conditioning deviceis simultaneously operated for cooling and heating during mainly performing the cooling operation, the outdoor heat exchangerfunctions as a condenser. In this case, the outdoor heat exchangercondenses the high-temperature and high-pressure gas-phase refrigerant discharged from the compressorby heat exchange, and changes the refrigerant into a high-pressure liquid-phase refrigerant.

The outdoor blowersucks outdoor air (hereinafter referred to as outside air) and blows the air which is subjected to the heat exchange in the outdoor heat exchangerto the outside. The outdoor air sucked by the outdoor bloweris blown onto the outdoor heat exchanger. Accordingly, heat exchange between the outdoor air and the refrigerant flowing through the outdoor heat exchangeris performed. The outdoor bloweris provided near the outdoor heat exchanger.

The outdoor expansion valveadjusts the flow rate of the refrigerant flowing through the outdoor heat exchangerin accordance with its opening. The outdoor expansion valvehas, for example, a valve structure in which the amount of throttled refrigerant is adjusted by controlling the opening of the valve between a minimum opening and a maximum opening, and is configured as a pulse motor valve (PMV) whose opening changes continuously in accordance with the number of drive pulses supplied. The outdoor expansion valvehas its opening adjusted by the control unit, and supplies a value of the current opening (actual opening) to the control unitby a wired or wireless manner.

In the example shown in, the outdoor expansion valveis provided in a flow path (hereinafter referred to as a liquid pipe)through which the liquid-phase refrigerant or the gas-liquid two-phase refrigerant flows. The liquid pipeis configured by, for example, connecting a plurality of pipes with a joint (for example, a packed valve) PV, with one end connected to the outdoor expansion valveand the other end connected to an indoor expansion valveof each indoor unitto be described later. The liquid pipeconstitutes a part of the outdoor side pipeand the indoor side pipe. As described above, in the present embodiment, the air conditioning deviceis simultaneously operated for cooling and heating during mainly performing the heating operation, i.e., the outdoor unitis operated for heating. For this reason, the liquid-phase refrigerant, the gas-liquid two-phase refrigerant or the like returned from the indoor unit(indoor unitin the example shown in) in heating operation (heating operation thermo-on state) flows through the liquid pipe.

Incidentally, when the air conditioning deviceis simultaneously operated for cooling and heating during mainly performing the cooling operation, i.e., when the outdoor unitis operated for cooling, the liquid phase refrigerant, the gas-liquid two-phase refrigerant, or the like, which is subjected to heat exchange in the outdoor heat exchangerflows through the liquid pipe. In this case, high-temperature and high-pressure gas phase refrigerant discharged from the compressoris guided by a second four-way valveto be described below to flow into the outdoor heat exchanger. At that time, the second four-way valvehas ports connected as represented by dashed lines in.

The outdoor temperature detection unitdetects the outdoor temperature, which is the temperature of the outside air, i.e., the outside air temperature. In this case, the outdoor area is an outdoor area opposed to an indoor area which is the space to be air-conditioned, for example, an outdoor space in which the outdoor heat exchangerand the outdoor blowerare provided, or the like. The outdoor temperature detection unitis, for example, a temperature sensor (thermistor) having a temperature sensor provided near the outdoor heat exchangerto detect the outdoor temperature. The outdoor temperature detection unitsupplies the detected outdoor temperature value to the control unitby a wired or wireless manner.

As described above, in the present embodiment, the air conditioning deviceis simultaneously operated for cooling and heating during mainly performing the heating operation, and, among the plurality of indoor units, indoor units which are in cooling operation and indoor units which are in heating operation exist (exist together). In the example shown in, among the three indoor units,, and, the indoor unitis in heating operation, i.e., in the heating operation thermo-on state, the indoor unitis in the heating operation thermo-off state, and the indoor unitis in cooling operation, i.e., in the cooling operation thermo-on state.

Each of the plurality of indoor unitsincludes as its main components an indoor heat exchanger, an indoor blower, an indoor expansion valve, an indoor temperature detection unit, and the like.

The indoor heat exchangersexchange heat between the indoor air and the refrigerant. In the present embodiment, indoor units which are in cooling operation and indoor units which are in heating operation exist (exist together), among the plurality of indoor units, and the indoor heat exchangersof the indoor unitsin cooling operation function as evaporators, and the indoor heat exchangersof the indoor unitsin heating operation function as condensers. In the example shown in, an indoor heat exchangerof the indoor unitin the heating operation thermo-on state and an indoor heat exchangerof the indoor unitin the heating operation thermo-off state function as condensers. In contrast, an indoor heat exchangerof the indoor unitin the cooling operation thermo-on state functions as an evaporator.

The indoor blowers(,, and) suck indoor air (hereinafter referred to as indoor air) and blow the air which is subjected to heat exchange in the indoor heat exchangersinto the room. The outside air sucked by the indoor blowersis blown against the indoor heat exchangers. Accordingly, heat exchange between the indoor air and the refrigerant flowing through the indoor heat exchangersis performed. The indoor blowersare provided near the indoor heat exchangers.

The indoor expansion valveadjusts the flow rate of the refrigerant flowing through the indoor heat exchangersin accordance with the opening. The indoor expansion valvehas, for example, a valve structure in which the amount of refrigerant throttling is adjusted by controlling the opening of the valve between the minimum opening and the maximum opening, and is configured as a pulse motor valve (PMV) whose opening changes continuously in accordance with the number of drive pulses supplied. The indoor expansion valvehas the opening adjusted by the control unit, and supplies the current opening (actual opening) value to the control unitby a wired or wireless manner.

The indoor expansion valveis provided in the liquid pipe. In the example shown in, an indoor expansion valveis provided in a first branch pipethat branches off from the liquid pipe. An indoor expansion valveis provided in a second branch pipethat branches off from the liquid pipe. An indoor expansion valveis provided in a third branch pipethat branches off from the liquid pipe. The third branch pipecorresponds to the other end of the liquid pipe.

When the indoor unitis in the cooling thermo-on state and the heating thermo-on state, the indoor expansion valveis opened. In contrast, when the indoor unitis in the cooling thermo-off state and the heating thermo-off state, the indoor expansion valveis closed. In addition, when the indoor unitis stopped, the indoor expansion valveis closed. In the example shown in, the indoor expansion valveof the indoor unitin the heating operation thermo-on state and the indoor expansion valveof the indoor unitin the cooling operation thermo-on state are opened. In contrast, the indoor expansion valveof the indoor unitin the heating operation thermo-off state is closed.

The indoor temperature detection unitdetects the indoor temperature, which is the temperature of the air in the room to be conditioned by the indoor unit, i.e., the inside air temperature. The indoor temperature detection unitis, for example, a temperature sensor (thermistor) that detects the indoor temperature by a temperature sensor provided in the housing of the indoor unitor the like. The indoor temperature detection unitsupplies the detected indoor temperature value to the control unitby a wired or wireless manner. In the example shown in, indoor temperature detection unit,, andare provided for three indoor units,, and, respectively.

Each of the plurality of switching unitsswitches the flow of refrigerant to either of two flow paths for cooling and heating between the outdoor unitand each of the plurality of indoor units. The switching unitsare provided for the plurality of indoor units, respectively. In the example shown in, three switching units,, andare provided to correspond to three indoor units,, and, respectively. In the following descriptions, an element common to these three switching units,, andwill be referred to as a switching unit, and components of each of the switching units,, andwill be given corresponding suffixes.

In order to switch the flow of the refrigerant in this manner, each of the switching unitshas two switching valvesand.

One of the two switching valves (hereinafter referred to as a first switching valve) switches between flowing in and blocking the refrigerant to the indoor heat exchanger. The first switching valveopens when the corresponding indoor unitis in the heating operation thermo-on state and the heating operation thermo-off state. On the other hand, the first switching valvecloses when the corresponding indoor unitis in the cooling operation thermo-on state and the cooling operation thermo-off state.

In contrast, the other of the two switching valves (hereinafter referred to as a second switching valve) switches between flowing in and blocking the refrigerant from the indoor heat exchanger. The second switching valveopens when the corresponding indoor unitis in the cooling operation thermo-on state and the cooling operation thermo-off state. On the other hand, the second switching valvecloses when the corresponding indoor unitis in the heating operation thermo-on state and the heating operation thermo-off state.

Incidentally, for example, at least one of the first switching valveand the second switching valvecloses when the corresponding indoor unitis stopped.

In the example shown in, the first switching valveof the switching unitcorresponding to the indoor unitin the heating operation thermo-on state and the first switching valveof the switching unitcorresponding to the indoor unitin the heating operation thermo-off state are open. On the other hand, the second switching valvesandof the switching unitsandcorresponding to these indoor unitsandare closed.

In contrast, the second switching valveof the switching unitcorresponding to the indoor unitin the cooling operation thermo-on state is open. On the other hand, the first switching valveof the switching unitcorresponding to this indoor unitis closed.

The first switching valveand the second switching valvehave, for example, a valve structure in which the flow of the refrigerant can be blocked by controlling the opening of the valves, and are configured as pulse motor valves (PMV) whose opening changes continuously in accordance with the number of drive pulses supplied. The first switching valveand the second switching valvehave operations controlled, for example, openings adjusted by a control unitto be described below, and supply values of the openings to the control unitby a wire or wireless manner.

In the example shown in, the first switching valveis provided in a flow path (hereinafter referred to as a first gas pipe)through which the high-temperature and high-pressure gas-phase refrigerant discharged from the compressorflows. The first gas pipeis configured to have, for example, a plurality of pipes connected with a joint (for example, a packed valve) PV, and one end is connected to the discharge pipevia a four-way valve (first four-way valve), and the other end is connected to the indoor heat exchangerof each indoor unit. The first gas pipeconstitutes a part of the outdoor side pipeand the indoor side pipe. In the example shown in, the first four-way valvehas one of its four ports blocked, and essentially functions as a three-way valve.

Incidentally, when the outdoor unitperforms the simultaneous cooling and heating operation during mainly performing the cooling operation for performing the cooling operation, the high-temperature and high-pressure gas-phase refrigerant discharged from the compressoris guided by the four-way valve (second four-way valve)and flows into the outdoor heat exchanger, and a part of the high-temperature and high-pressure gas-phase refrigerant discharged from the compressoris guided by the first four-way valveand flows through the first gas pipe.

The first switching valveis provided in a first branch pipethat branches off from the first gas pipe. The first switching valveis provided in a second branch pipethat branches off from the first gas pipe. The first switching valveis provided in a third branch pipethat branches off from the first gas pipe. The third branch pipecorresponds to the other end of the first gas pipe.

In the example shown in, the second switching valveis provided in a flow path (hereinafter referred to as a second gas pipe)through which the refrigerant flowing out of the indoor heat exchangerof the indoor unitin cooling operation (cooling thermo-on state), for example, the gas-phase refrigerant evaporated in the indoor heat exchangeror the gas-liquid two-phase refrigerant, flows. The second gas pipeis configured to have, for example, a plurality of pipes connected with a joint (for example, packed valve) PV, and one end is connected to the indoor heat exchangerof each indoor unit, and the other end is connected to an accumulator (first accumulator). The second gas pipemerges with the first gas pipebetween the indoor heat exchangerand the switching unit(the first switching valveand the second switching valve). The second gas pipeconstitutes a part of the outdoor side pipeand the indoor side pipe.

The accumulatorseparates the refrigerant flowing out from the indoor heat exchangerof the indoor unitduring the cooling operation into gas and liquid, and supplies only the gas-phase refrigerant to the compressor. The refrigerant separated into gas and liquid in the accumulatoris guided to a gas-liquid separator (second accumulator). The gas-liquid separatorfurther separates the refrigerant into gas and liquid such that the compressordoes not compress the liquid-phase refrigerant.

The second switching valveis provided in a first branch pipethat branches off from the second gas pipe. The second switching valveis provided in a second branch pipethat branches off from the second gas pipe. The second switching valveis provided in a third branch pipethat branches off from the second gas pipe. The third branch pipecorresponds to one end of the second gas pipe.

In the air conditioning deviceconfigured as described above, the refrigerant flows as indicated by white arrows in. The gas phase refrigerant discharged from the compressorto the discharge pipeis guided to the first gas pipeby the first four-way valve. The refrigerant flowing through the first gas pipeflows into the indoor heat exchangerthrough the first switching valveof the switching unitcorresponding to the indoor unitin heating operation (heating operation thermo-on state). The refrigerant which flows into the indoor heat exchangerand changes to the liquid phase or gas-liquid phases flows into the liquid pipethrough the indoor expansion valve