JP7535683B2 - Air Conditioning Equipment - Google Patents

Description

The present invention relates to an air-conditioning system that is configured by connecting one outdoor unit to multiple indoor units.

Patent Document 1 discloses an air conditioner that is configured by connecting one outdoor unit to multiple indoor units. In this air conditioner, multiple indoor units are connected to one outdoor unit via a four-way switching valve, and an expansion valve is provided in the refrigerant circuit configured by the outdoor unit and each of the multiple indoor units, for example, in this example, in the refrigerant circuit inside each indoor unit. The four-way switching valve switches the refrigerant flow direction to perform cooling or heating operation, and the opening of the expansion valve is varied to control the cooling or heating capacity of each indoor unit, and when the thermostat is turned off, the indoor unit closes its expansion valve to stop operation of that indoor unit.

Japanese Patent Application Publication No. 10-132357

This disclosure provides a comfortable air conditioner that suppresses refrigerant flow noise generated from the stopped indoor units when the compressor of the air conditioner consisting of one outdoor unit and multiple indoor units is stopped and pressure differences between the multiple indoor units and the outdoor unit are eliminated and equalized.

The air conditioner disclosed herein is an air conditioner in which multiple indoor units equipped with indoor heat exchangers are connected to one outdoor unit having a compressor, a four-way switching valve, and an outdoor heat exchanger, and an expansion valve is connected to each of the refrigerant circuits formed by the compressor, four-way switching valve, outdoor heat exchanger of the outdoor unit, and the indoor heat exchangers of the multiple indoor units. The air conditioner is equipped with outdoor unit pressure detection means that indirectly or directly detects the pressure of the outdoor unit, indoor unit pressure detection means that indirectly or directly detects the pressure of the multiple indoor units, and a control unit that controls the expansion valves, and the control unit is configured to calculate the respective pressure differences between the outdoor unit pressure detected by the outdoor unit pressure detection means and each indoor unit pressure detected by the indoor unit pressure detection means after the compressor is stopped, and open the expansion valves to a predetermined opening degree in the order from the indoor unit with the largest pressure difference to the indoor unit with the smallest pressure difference.

The air conditioner disclosed herein is an air conditioner in which multiple indoor units equipped with indoor heat exchangers are connected to one outdoor unit having a compressor, a four-way switching valve, and an outdoor heat exchanger, and an expansion valve is connected to each of the refrigerant circuits formed by the compressor, four-way switching valve, outdoor heat exchanger of the outdoor unit, and the indoor heat exchangers of the multiple indoor units. The air conditioner is equipped with an outdoor heat exchanger temperature sensor that detects the temperature of the outdoor heat exchanger, each indoor heat exchanger temperature sensor that detects the temperature of the multiple indoor heat exchangers, and a control unit that controls the expansion valves. After the compressor is stopped, the control unit calculates the temperature difference between the outdoor heat exchanger temperature detected by the outdoor heat exchanger temperature sensor and each indoor heat exchanger temperature detected by the indoor heat exchanger temperature sensor, and opens the expansion valves to a predetermined opening degree in the order from the indoor unit with the largest temperature difference to the indoor unit with the smallest temperature difference.

The air conditioner of the present disclosure eliminates and equalizes the pressure difference between the indoor units among multiple indoor units connected to the outdoor unit, starting with the indoor unit with the largest pressure difference from the outdoor unit and then the indoor unit with the smallest pressure difference. This makes it possible to suppress the generation of refrigerant flow noise in indoor units that are not operating, resulting in a comfortable air conditioner.

Refrigeration cycle configuration diagram of an air conditioner according to the first embodiment Control block diagram of the air conditioner Control flow diagram of the air conditioner FIG. 2 is an explanatory diagram of the operation of each indoor unit of the air conditioner.

(Knowledge and other information that forms the basis of this disclosure)
At the time when the inventors came up with the present disclosure, an air conditioner configured by connecting one outdoor unit and multiple indoor units, as disclosed in Patent Document 1, is provided with an expansion valve corresponding to each indoor unit, and the cooling or heating capacity is controlled by varying the opening degree of this expansion valve. In this air conditioner with an expansion valve provided in each indoor unit, different high and low pressure differences occur between the outdoor unit side and the multiple indoor unit sides immediately after stopping the air conditioning operation, i.e., stopping the compressor, so in order to eliminate this condition and equalize the high and low pressure balance, the expansion valves of each indoor unit are opened simultaneously to a predetermined large opening degree. At this time, there is a problem that a sudden and large refrigerant flow occurs in the indoor unit that is stopped by thermo-off or the like due to the high and low pressure difference of the indoor units, generating refrigerant flow noise, and it was found that this noise is one of the factors that impair the reliability and comfort of users.

The inventors discovered this problem and came to define the subject of this disclosure in order to solve it.

Therefore, this disclosure provides a highly reliable and comfortable air conditioner by suppressing refrigerant flow noise when the compressor is stopped.

Below, the embodiments will be described in detail with reference to the drawings. However, more detailed explanations than necessary may be omitted. For example, detailed explanations of matters that are already well known, or duplicate explanations of substantially identical configurations may be omitted. This is to avoid making the following explanation unnecessarily redundant and to make it easier for those skilled in the art to understand.

The accompanying drawings and the following description are provided to enable those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter described in the claims.

(Embodiment 1)
Hereinafter, the first embodiment will be described with reference to FIGS. 1 to 4. FIG.

[1-1. Configuration]
FIG. 1 is a diagram showing the configuration of an air conditioning apparatus according to the first embodiment.

The air conditioning device of this embodiment is configured with multiple indoor units 11a to 11d connected in parallel to one outdoor unit 1, and refrigerant compressed in the outdoor unit 1 is circulated between the outdoor unit 1 and the indoor units 11a to 11d to condition the conditioned space in which the indoor units 11a to 11d are installed.

The outdoor unit 1 has a compressor 2 that compresses the refrigerant, a compressor temperature sensor 3, a four-way switching valve 4 that switches the flow direction of the refrigerant to switch between cooling operation for cooling the space to be conditioned and heating operation for heating the space to be conditioned, an outdoor heat exchanger 6 that exchanges heat between the refrigerant from the four-way switching valve 4 and the air blown from the outdoor fan 5, an outdoor unit pressure detection means that indirectly detects the refrigerant pressure of the outdoor unit 1, a liquid side shutoff valve 8 and a gas side shutoff valve 16 that are composed of an electromagnetic valve or the like. The outdoor heat exchanger 6 exchanges heat with the refrigerant in the outdoor unit 1, functions as a condenser in the cooling operation mode, and functions as an evaporator in the heating operation mode.

The outdoor unit pressure detection means indirectly detects the refrigerant pressure of the outdoor unit 1 by detecting the temperature of the outdoor heat exchanger 6 using the outdoor heat exchanger temperature sensor 7.

In addition, in this embodiment, the outdoor unit 1 is provided with expansion valves 9a to 9d via a liquid-side shutoff valve 8, and is connected to multiple indoor units 11a to 11d, which will be described later.

The expansion valves 9a to 9d reduce the pressure of the high-pressure refrigerant to expand it, and their opening is adjusted under the control of the control unit 17 (described later), and they also have the function of cutting off the refrigerant.

In this example, the expansion valves 9a to 9d are all located on the outdoor unit 1 side, but they may be located on each of the indoor units 11a to 11d (described later) or in the connecting pipes between the outdoor unit 1 and each of the indoor units 11a to 11d.

On the other hand, each of the indoor units 11a to 11d is connected to the outdoor unit 1 via liquid side connections 10a to 10d and gas side connections 15a to 15d, and is equipped with indoor heat exchangers 12a to 12d that exchange heat with the refrigerant supplied from the outdoor unit 1, indoor unit pressure detection means that indirectly detects the refrigerant pressure of the indoor units 11a to 11d, and indoor fans 14a to 14d that blow air to the indoor heat exchangers 12a to 12d.

The indoor unit pressure detection means indirectly detects the refrigerant pressure of the indoor units 11a to 11d by detecting the temperature of the indoor heat exchangers 12a to 12d using the indoor heat exchanger temperature sensors 13a to 13d.

The indoor heat exchangers 12a to 12d function as evaporators in the cooling operation mode, evaporating the refrigerant that has been depressurized by the expansion valves 9a to 9d.

Although not shown, the air conditioner is equipped with various components for efficiently operating the refrigeration cycle, such as an accumulator that separates liquid refrigerant from gaseous refrigerant and stores the refrigerant.

The air conditioner also includes a control unit 17 that controls operation. This control unit 17 controls the operation of the compressor 2, the flow path switching control of the four-way switching valve 4, and the operation or stopping of the outdoor fan 5.

Furthermore, the control unit 17 controls the opening and/or opening/closing of each expansion valve 9a-9d as described above. In addition to adjusting the opening based on the temperature difference between the room temperature and the set temperature, the control of each expansion valve 9a-9d sequentially controls the opening of each expansion valve 9a-9d corresponding to each of the multiple indoor units 11a-11d to a predetermined opening based on the difference between the temperature as a pressure substitute value detected by the outdoor heat exchanger temperature sensor 7 of the outdoor unit 1 and the temperature as a pressure substitute value detected by the indoor heat exchanger temperature sensors 13a-13d of each indoor unit 11a-11d when the compressor is stopped during operation stop, switching from cooling operation to heating operation, or vice versa.

Figure 2 shows the control block that controls the expansion valves 9a to 9d. The control unit 17 has a time control unit 17a, a pressure difference calculation means 17b, a priority order determination means 17c, an expansion valve control means 17d, and a full-open operation determination means 17e.

The time control unit 17a measures the time since compressor 2 stopped.

The pressure difference calculation means 17b is for detecting each pressure difference between the outdoor unit 1 and each of the multiple indoor units 11a to 11d, and in this example calculates the pressure difference from the difference between the temperature detected as a pressure substitute value by the outdoor heat exchanger temperature sensor 7 and the temperature detected as a pressure substitute value by each of the indoor heat exchanger temperature sensors 13a to 13d.

The priority order determination means 17c determines the order in which the expansion valves 9a to 9d are opened to a predetermined opening degree based on the temperature difference calculated by the pressure difference calculation means 17b as a substitute pressure value.

The expansion valve control means 17d opens each expansion valve 9a-9d to a predetermined degree of opening, in this example to a fully open state, in the order determined by the priority order determination means 17c. This expansion valve control means 17d opens the expansion valves 9a-9d to a predetermined degree of opening in the order of the largest temperature difference as a pressure substitute value. Then, after the previous expansion valve has finished opening to the predetermined degree of opening, it starts opening the next expansion valve.

The full-open operation determination means 17e detects that each expansion valve 9a to 9d has opened to a predetermined opening degree and outputs a signal to the expansion valve control means 17d.

The indoor control devices 18a to 18d are indoor control devices provided in each of the indoor units 11a to 11d, and output the temperature output, which is a pressure substitute value, from each of the indoor heat exchanger temperature sensors 13a to 13d to the pressure difference calculation means 17b.

In this embodiment, the indoor control devices 18a to 18d and the control unit 17 of the outdoor unit 1 cooperate to control operation such as cooling and heating, and air-condition the space to be conditioned to the target temperature.

[1-2. Operation]
Next, the operation and effect of the air conditioner configured as above will be described with reference to Figs.

The air conditioner of this embodiment performs cooling operation, heating operation, etc. when the user instructs it to operate. During cooling operation, heating operation, etc., the air conditioner controls the operating frequency and operation/stop of compressor 2, adjusts the opening of each expansion valve 9a-9d, and controls outdoor fan 5 and indoor fans 14a-14d according to the target temperature set by the user, and conditions the conditioned space according to the target temperature.

For example, when the user stops the air conditioning operation, or switches from cooling operation to heating operation or vice versa, the control unit 17 stops the compressor 2 of the outdoor unit 1, and after a predetermined time shown in step 1 of FIG. 3 has elapsed, for example, 1 to 2 minutes, the pressure difference calculation means 17b calculates the temperature difference between the outdoor unit 1 and each of the indoor units 11a to 11d in step 2, which becomes the pressure substitute value, and the process proceeds to step 3.

In step 3, it is determined whether there are multiple indoor units in operation (hereafter referred to as operating units), and if there are multiple, the process proceeds to step 4 and onwards.

In step 4, the expansion valve 9a of the operating unit (shown in FIG. 4 as operating unit operation priority 1) that has the largest temperature difference between the outdoor unit 1 and the operating unit among the multiple operating units is instructed to open to a greater degree than during normal operation, in this example, fully open (a in FIG. 4). Then, in step 5, the expansion valve 9a of the operating unit with the largest temperature difference between the outdoor unit 1 is fully opened (b in FIG. 4), and then the process moves to step 6, where the expansion valve 9b of the operating unit (shown in FIG. 4 as operating unit operation priority 2) that has the next largest temperature difference between the outdoor unit 1 is fully opened (c in FIG. 4), and in step 7, the fully open operation of the expansion valve 9b is completed (d in FIG. 4), and the process moves to step 8.

Then, in step 8, it is determined whether the expansion valves of all operating units, in this case expansion valves 9a and 9b, have been fully opened, and steps 4 to 7 are repeated until this is complete. This operation is performed as many times as there are operating units.

This eliminates the pressure difference between the indoor units and the outdoor unit 1, starting with the operating unit with the largest temperature difference, which serves as the pressure substitute value, and equalizes the pressure.

In other words, the pressures of the outdoor unit 1 and each of the indoor units 11a-11d are detected by the temperature that changes according to the pressure, and the expansion valves 9a-9d of each of the indoor units 11a-11d are opened to a specified opening degree in descending order of temperature difference, eliminating the pressure differences between the indoor units 11a-11d in order from the operating unit with the largest temperature difference to the operating unit with the smallest temperature difference from the outdoor unit 1, and equalizing the pressure.

Therefore, even if there is an indoor unit (hereafter referred to as the stopped unit) that is not operating when the compressor is stopped and there is a large pressure difference between the stopped unit and the outdoor unit 1, the pressure difference is extremely small compared to the conventional method of fully opening the expansion valves of all operating units at once. Therefore, even if the expansion valve of the stopped unit is fully opened, the flow of refrigerant within the stopped unit is gentle and almost no refrigerant flow noise is generated.

In addition, in this embodiment, the expansion valves are fully opened in descending order of the temperature difference that serves as the pressure substitute value, so pressure equalization can be achieved smoothly and step by step between the outdoor unit 1 and each operating unit. This makes it possible to suppress the discomfort that can occur when differences in the momentum of the refrigerant flow occur during pressure equalization.

Furthermore, the opening operation of each expansion valve begins after the expansion valve of the operating unit that is first to be pressure equalized has finished opening to its fully open state, so the pressure difference is reliably eliminated for each operating unit. Therefore, the overlap of the pressure difference elimination operation of the operating unit, which occurs when the next expansion valve is opened before the expansion valve is fully open, creates a difference in momentum in the refrigerant flow, and the discomfort felt by small and large differences in the refrigerant flow sound can be reliably suppressed.

Furthermore, the pressure in the outdoor unit and each indoor unit is indirectly detected by temperature sensors, making it easier to install the sensors themselves compared to using pressure sensors that directly detect pressure, simplifying the configuration and reducing the cost of the sensors themselves.

If it is determined in step 3 that there is not more than one operating unit, that is, that there is only one operating unit, the process proceeds to step 9, where an instruction is given to fully open, for example, expansion valve 9a, of the operating unit in question, and the fully opening operation is completed in step 10, after which the process proceeds to step 11, where confirmation is made as to whether or not there is a stopped unit. In this case, as in the above, the pressure difference between the stopped unit that was stopped when the compressor was stopped and outdoor unit 1 is minimized, the flow of refrigerant in the stopped unit is gentle, and almost no refrigerant flow noise is generated.

Next, in steps 8 and 10 above, once it has been confirmed that the expansion valves of all operating units, in this example 9a and 9b, have been fully opened, the process proceeds to step 11, where it is determined whether there are multiple units that have stopped when the compressor is stopped. If there are multiple units that have stopped, the process proceeds to step 12 and onwards.

First, in step 12, an instruction is given to open, for example, the expansion valve 9c connected to the stopped unit (shown as stopped unit operation priority 1 in FIG. 4) with the largest temperature difference that serves as a pressure substitute value with the outdoor unit 1 among the multiple stopped units to a large degree, in this example, to be fully opened (e in FIG. 4). Then, in step 13, the operation of fully opening the expansion valve 9c of the stopped unit with the largest temperature difference that serves as a pressure substitute value with the outdoor unit 1 is completed (f in FIG. 4), and then the process moves to step 14, where an instruction is given to fully open, for example, the expansion valve 9d of the stopped unit with the next largest temperature difference that serves as a pressure substitute value with the outdoor unit 1 (g in FIG. 4), and in step 15 the operation of fully opening the expansion valve 9d is completed (h in FIG. 4), and the process moves to step 16.

In step 16, it is determined whether the expansion valves 9c and 9d of all stopped units have been fully opened, and steps 12 to 15 are repeated until this is complete. This operation is repeated as many times as there are stopped units.

This effectively suppresses the sudden flow of refrigerant that occurs in the stopped unit, which eliminates the pressure difference between the outdoor unit 1, and more effectively suppresses the generation of refrigerant flow noise.

In other words, in the same way as the pressure equalization operation of the operating units, the pressure difference between the indoor units and the stopped units that are not operating when the compressor is stopped is eliminated in the order of the stopped units with the largest temperature difference, which serves as a pressure substitute value between the outdoor unit 1 and the stopped units with the smallest temperature difference, and the pressure is equalized to suppress the generation of refrigerant flow noise.

The order in which the expansion valves 9c and 9d are fully opened, and the operation of opening the next expansion valve after fully opening them, is the same as in the case of the operating unit, and the same effects are obtained.

If it is determined in step 11 that there are not multiple stopped units, that is, if there is only one stopped unit, the process proceeds to step 17, the expansion valve of the corresponding stopped unit is fully opened, and expansion valve control when the compressor is stopped is terminated. In this case, as in the above, pressure equalization of the operating units is completed, so the pressure difference between the stopped unit that was not operating when the compressor was stopped and the outdoor unit 1 is minimized, the flow of refrigerant in the stopped unit is gentle, and almost no refrigerant flow noise is generated.

In the above, in this embodiment, the outdoor unit pressure detection means and indoor unit pressure detection means for detecting the refrigerant pressure of the outdoor unit 1 and each indoor unit 11a to 11d are configured with a temperature sensor that detects the temperature that serves as a pressure substitute value. However, this may be configured with a pressure detector such as a pressure sensor that directly detects the refrigerant pressure of the outdoor unit 1 and each indoor unit 11a to 11d, for example, the refrigerant pressure of each heat exchanger part. In addition, in this embodiment, the pressure of the outdoor unit and each indoor unit is indirectly detected by temperature detection using a temperature sensor, but the expansion valves 9a to 9d may be controlled directly using the temperatures detected by the outdoor heat exchanger temperature sensor 7 and the indoor heat exchanger temperature sensors 13a to 13d. In that case, the control unit 17 has a temperature difference calculation means for calculating the difference between the temperature detected by the outdoor heat exchanger temperature sensor 7 and the temperature detected by each indoor heat exchanger temperature sensor 13a to 13d instead of the pressure difference calculation means 17b.

In addition, the expansion valves 9a to 9d are fully open during pressure equalization to eliminate the pressure difference between the outdoor unit 1 and each of the indoor units 11a to 11d, but this can be set to any desired opening.

Furthermore, although an example has been given in which there are four indoor units 11a to 11d, this can be any number provided there is more than one.

[1-3. Effects, etc.]
As described above, the air conditioner of the present disclosure is an air conditioner in which a plurality of indoor units 11a to 11d each equipped with indoor heat exchangers 12a to 12d are connected to one outdoor unit 1 having a compressor 2, a four-way switching valve 4, and an outdoor heat exchanger 6, and expansion valves 9a to 9d are connected midway through a refrigerant circuit made up of the compressor 2, four-way switching valve 4, outdoor heat exchanger 6 of the outdoor unit 1, and the indoor heat exchangers 12a to 12d of the plurality of indoor units 11a to 11d, and the pressure of the outdoor unit 1 is indirectly or directly detected. The control unit 17 is configured to calculate, after the compressor 2 is stopped, the respective pressure differences between the outdoor unit pressure detected by the outdoor unit pressure detection means and each indoor unit pressure detected by the indoor unit pressure detection means, and to open the expansion valves 9a to 9d to a predetermined opening degree in the order from the indoor unit with the largest pressure difference to the indoor unit with the smallest pressure difference.

As a result, among the multiple indoor units 11a to 11d connected to the outdoor unit 1, the pressure difference between the outdoor unit 1 is eliminated and equalized, starting with the indoor unit with the largest pressure difference and then the indoor unit with the smallest pressure difference. This makes it possible to suppress the generation of refrigerant flow noise in indoor units that are not operating, resulting in a comfortable air conditioning system.

In addition, in the air conditioning device of the present disclosure, the outdoor unit pressure detection means is configured with an outdoor heat exchanger temperature sensor 7 that detects the temperature of the outdoor heat exchanger 6 to indirectly detect the pressure of the outdoor unit, and the indoor unit pressure detection means is configured with indoor heat exchanger temperature sensors 13a to 13d that detect the temperatures of the indoor heat exchangers 12a to 12d to indirectly detect the pressure of the indoor units 11a to 11d, and after the compressor is stopped, the control unit 17 calculates the temperature difference between the outdoor heat exchanger temperature detected by the outdoor heat exchanger temperature sensor 7 and each of the multiple indoor heat exchanger temperatures detected by the indoor heat exchanger temperature sensors 13a to 13d, and opens the expansion valves to a predetermined opening degree in the order from the indoor unit with the largest temperature difference to the indoor unit with the smallest temperature difference.

This not only suppresses the generation of refrigerant flow noise, but also allows the pressure difference between the outdoor unit 1 and the indoor units 11a to 11d to be detected by the temperature difference, making it possible to provide an air conditioner more simply and inexpensively than if a pressure sensor that directly detects pressure were used.

In addition, the control unit 17 in the air conditioning device disclosed herein is configured such that, when multiple indoor units include indoor units that are operating and indoor units that are stopped, the expansion valve of the indoor unit that is operating is opened to a predetermined opening degree, and then the expansion valve of the indoor unit that is stopped is opened.

This allows smooth pressure equalization of the indoor units for both operating and stopped units, suppressing refrigerant flow noise without creating an unpleasant feeling, making it possible to create a highly comfortable air conditioning system even when multiple operating and stopped units are mixed.

The control unit 17 in the air conditioning device disclosed herein is configured to start the opening operation of the next expansion valve after the previous expansion valve has finished opening to a predetermined degree.

This prevents the pressure difference elimination operations of the indoor units 11a to 11d from partially overlapping, which can cause differences in the momentum of the refrigerant flow, reducing the discomfort caused by differences in the sound of the refrigerant flow, and further increasing comfort to a higher level.

The air conditioner disclosed herein is an air conditioner in which a single outdoor unit 1 having a compressor 2, a four-way switching valve 4, and an outdoor heat exchanger 6 is connected to a plurality of indoor units 11a to 11d each equipped with indoor heat exchangers 12a to 12d, and expansion valves 9a to 9d are connected midway through a refrigerant circuit made up of the compressor 2, four-way switching valve 4, outdoor heat exchanger 6 of the outdoor unit 1, and the indoor heat exchangers 12a to 12d of the plurality of indoor units 11a to 11d, respectively, and further includes an outdoor heat exchanger temperature sensor 7 for detecting the temperature of the outdoor heat exchanger 6, and an outdoor heat exchanger temperature sensor 8 for detecting the temperature of the outdoor heat exchanger 6, and an outdoor heat exchanger temperature sensor 9 for detecting the temperature of the outdoor heat exchanger 6. The system is equipped with indoor heat exchanger temperature sensors 13a-13d that detect the temperatures of the indoor heat exchangers 12a-12d, and a control unit 17 that controls the expansion valves 9a-9d. After the compressor 2 is stopped, the control unit 17 calculates the temperature difference between the outdoor heat exchanger temperature detected by the outdoor heat exchanger temperature sensor 7 and the indoor heat exchanger temperatures detected by the indoor heat exchanger temperature sensors 13a-13d, and opens the expansion valves 9a-9d to a predetermined opening degree in the order from the indoor unit with the largest temperature difference to the indoor unit with the smallest temperature difference.

This not only suppresses the generation of refrigerant flow noise, but also allows the pressure difference between the outdoor unit 1 and the indoor units 11a to 11d to be detected by the temperature difference, making it possible to provide an air conditioner more simply and inexpensively than if a pressure sensor that directly detects pressure were used.

The air conditioning device according to the present invention has been described above using the above embodiment, but the present invention is not limited to this, and various modifications, substitutions, additions, omissions, etc. can be made. In other words, the embodiment disclosed here is illustrative in all respects and is not restrictive, and the scope of the present invention is indicated by the claims, and includes all modifications within the meaning and scope equivalent to the claims.

As described above, when equalizing the pressure difference between an indoor unit (stopped unit) that has stopped operating and an outdoor unit, the air conditioner according to the present invention can suppress the generation of refrigerant flow noise caused by the refrigerant flowing forcefully into the indoor unit (stopped unit), resulting in a comfortable air conditioner. Therefore, it can be widely used in home and commercial air conditioners, etc., and has great industrial value.

REFERENCE SIGNS LIST 1 Outdoor unit 2 Compressor 3 Compressor temperature sensor 4 Four-way switching valve 5 Outdoor fan 6 Outdoor heat exchanger 7 Outdoor heat exchanger temperature sensor 8 Liquid side stop valve 9a-9d Expansion valve 10a-10d Liquid side connection 11a-11d Indoor unit 12a-12d Indoor heat exchanger 13a-13d Indoor heat exchanger temperature sensor 14a-14d Indoor fan 15a-15d Gas side connection 17 Control unit 17a Time control unit 17b Pressure difference calculation means 17c Priority order determination means 17d Expansion valve control means 17e Full open operation determination means

Claims (7)

An air-conditioning apparatus comprising: a single outdoor unit having a compressor, a four-way switching valve, and an outdoor heat exchanger; a plurality of indoor units each having an indoor heat exchanger; and an expansion valve connected midway through a refrigerant circuit formed by the compressor, the four-way switching valve, and the outdoor heat exchanger of the outdoor unit, and the indoor heat exchangers of the plurality of indoor units;
an outdoor unit pressure detection means for indirectly or directly detecting the pressure of the outdoor unit;
an indoor unit pressure detection means for indirectly or directly detecting the pressures of the indoor units;
A control unit that controls the expansion valve,
The control unit calculates, after the compressor is stopped, the pressure difference between the outdoor unit pressure detected by the outdoor unit pressure detection means and each indoor unit pressure detected by the indoor unit pressure detection means, and opens the expansion valve to a predetermined opening degree in the order of indoor units with the largest pressure difference to indoor units with the smallest pressure difference. The outdoor unit pressure detection means is configured with an outdoor heat exchanger temperature sensor that detects the temperature of the outdoor heat exchanger to indirectly detect the pressure of the outdoor unit, and the indoor unit pressure detection means is configured with an indoor heat exchanger temperature sensor that detects the temperature of the indoor heat exchanger to indirectly detect the pressure of the indoor unit,
The air conditioning apparatus of claim 1, wherein the control unit calculates, after the compressor is stopped, the temperature difference between the outdoor heat exchanger temperature detected by the outdoor heat exchanger temperature sensor and each of the multiple indoor heat exchanger temperatures detected by the indoor heat exchanger temperature sensors, and opens the expansion valves to a predetermined opening degree in the order of indoor units with the largest temperature difference to indoor units with the smallest temperature difference. The air conditioner according to claim 1 or 2, wherein the control unit is configured to open the expansion valve of the indoor unit in operation to a predetermined opening degree and then open the expansion valve of the indoor unit that is not in operation to a predetermined opening degree when the indoor units include an indoor unit in operation and an indoor unit that is not in operation. An air conditioner according to any one of claims 1 to 3, wherein the control unit is configured to start the opening operation of the next expansion valve after the previous expansion valve has finished opening to a predetermined degree. An air-conditioning apparatus comprising: a single outdoor unit having a compressor, a four-way switching valve, and an outdoor heat exchanger; a plurality of indoor units each having an indoor heat exchanger; and an expansion valve connected midway through a refrigerant circuit formed by the compressor, the four-way switching valve, and the outdoor heat exchanger of the outdoor unit, and the indoor heat exchangers of the plurality of indoor units;
an outdoor heat exchanger temperature sensor for detecting a temperature of the outdoor heat exchanger;
a plurality of indoor heat exchanger temperature sensors for detecting temperatures of the indoor heat exchangers;
A control unit that controls the expansion valve,
The control unit calculates, after the compressor is stopped, the temperature difference between the outdoor heat exchanger temperature detected by the outdoor heat exchanger temperature sensor and each indoor heat exchanger temperature detected by the indoor heat exchanger temperature sensor, and opens the expansion valve to a predetermined opening degree in the order of indoor units with the largest temperature difference to indoor units with the smallest temperature difference. The air conditioner according to claim 5, wherein the control unit is configured to open the expansion valve of the indoor unit in operation to a predetermined opening degree and then open the expansion valve of the indoor unit that is not in operation to a predetermined opening degree when the indoor units include an indoor unit in operation and an indoor unit that is not in operation. An air conditioner according to claim 5 or 6, wherein the control unit is configured to start the opening operation of the next expansion valve after the opening operation of the previous expansion valve to a predetermined opening degree is completed.