GB2555255A

GB2555255A - Air conditioning device

Info

Publication number: GB2555255A
Application number: GB1717847.6A
Authority: GB
Inventors: Kimura Takanao
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2015-05-25
Filing date: 2015-05-25
Publication date: 2018-04-25
Anticipated expiration: 2035-05-25
Also published as: JP6415709B2; GB2555255C; GB201717847D0; WO2016189626A1; GB2555255B; JPWO2016189626A1

Abstract

This air conditioning device 1 is provided with: a refrigerant circuit 2 in which a compressor 4, a plurality of indoor heat exchangers 6, a plurality of expansion units 7 and an outdoor heat exchanger 8 are coupled to one another using pipelines; a bypass circuit 3 which bypasses at least one of the indoor heat exchangers 6; a heat accumulating vessel 11 which is provided in the bypass circuit 3 and which accumulates heat; and a circuit switching unit 12 which is provided in a connecting portion between the refrigerant circuit 2 and the bypass circuit 3, and which switches between causing the refrigerant to flow through the refrigerant circuit 2 or through the bypass circuit 3.

Description

(54) Title of the Invention: Air conditioning device Abstract Title: Air conditioning device (57) This air conditioning device 1 is provided with: a refrigerant circuit 2 in which a compressor 4, a plurality of indoor heat exchangers 6, a plurality of expansion units 7 and an outdoor heat exchanger 8 are coupled to one another using pipelines; a bypass circuit 3 which bypasses at least one of the indoor heat exchangers 6; a heat accumulating vessel 11 which is provided in the bypass circuit 3 and which accumulates heat; and a circuit switching unit 12 which is provided in a connecting portion between the refrigerant circuit 2 and the bypass circuit 3, and which switches between causing the refrigerant to flow through the refrigerant circuit 2 or through the bypass circuit 3.

1/3

rib. Z

INPUT UNIT 15

2/3

FIG. 3

HEAT STORING

OPERATION

HEATING

OPERATION

ADJUST OPENIN

OF EXPANSION UNIT TO {V STB NORMAL OPENING DEGREE!

t

3/3

FIG. 4 ____________________DEFROSTING SIGNAL

QSTART CONTROL )

................................1...........................

[ CHANGE AIR OF FAN TOΊ

I LIGHT AIR OR STOP FAN]^ ST11

DESCRIPTION

Title of Invention

AIR-CONDITIONING APPARATUS

Technical Field [0001]

The present invention relates to an air-conditioning apparatus including a refrigerant circuit through which refrigerant flows.

Background Art [0002]

An air-conditioning apparatus has been known that includes a plurality of indoor units. When a heating operation is not being performed in one of the indoor units in such an air-conditioning apparatus, an expansion unit of an indoor heat exchanger of the indoor unit is fully closed. In the state in which the heating operation is not being performed, the indoor unit may be stopped, performing an airsending operation, or in a thermo-off state during the heating operation, for example. In recent years, operation patterns of the air-conditioning apparatus have diversified with an increase in the number of connected indoor heat exchangers due to an increase in the number of connected indoor units. Consequently, when the heating operation is being performed only in a small-capacity indoor heat exchanger of the multiple connected indoor heat exchangers and a non-heating operation is being performed in the other indoor heat exchangers, the refrigerant may accumulate in the indoor heat exchangers with the fully closed expansion units. Consequently, a refrigerant circuit of the air-conditioning apparatus may operate with insufficient refrigerant.

[0003]

Patent Literature 1 discloses an air-conditioning apparatus that only slightly opens the expansion unit ofthe indoor heat exchanger not performing the heating operation. Patent Literature 1 aims to reduce the accumulation of the refrigerant in the indoor heat exchanger by opening the expansion unit by a slight opening degree instead of fully closing the expansion unit.

Citation List

Patent Literature [0004]

Patent Literature 1: Japanese Patent No. 3856520 Summary of Invention Technical Problem [0005]

In the air-conditioning apparatus disclosed in Patent Literature 1, however, the expansion unit opened by the slight opening degree allows the refrigerant to flow through the indoor heat exchanger, although the amount of the refrigerant is small. Consequently, heating is performed to some extent even during the non-heating operation. That is, extra heating occurs.

[0006]

The present invention has been made with the above-described issue as a background, and provides an air-conditioning apparatus that reduces the extra heating.

Solution to Problem [0007]

An air-conditioning apparatus according to an embodiment of the present invention includes a refrigerant circuit connecting, by pipes, a compressor, a plurality of indoor heat exchangers, a plurality of expansion units, and an outdoor heat exchanger, and allowing refrigerant to flow through the refrigerant circuit, a bypass configured to bypass at least one of the plurality of indoor heat exchangers, a heat storing container provided to the bypass to store heat, and a circuit switching unit provided to a connecting part connecting the refrigerant circuit and the bypass, and configured to switch the refrigerant to flow through the refrigerant circuit or the bypass.

Advantageous Effects of Invention [0008]

According to an embodiment of the present invention, the heat storing container is provided to the bypass that bypasses the at least one of the plurality of indoor heat exchangers. It is therefore possible to allow high-temperature and highpressure refrigerant to flow through the heat storing container in the non-heating operation. Consequently, it is possible to store heat in the heat storing container, and thereby to reduce the extra heating in the air-conditioning apparatus. Further, the heat stored in the heat storing container is usable for another purpose.

Brief Description of Drawings [0009] [Fig. 1] Fig. 1 is a circuit diagram illustrating an air-conditioning apparatus 1 according to Embodiment 1 of the present invention.

[Fig. 2] Fig. 2 is a functional block diagram illustrating the air-conditioning apparatus 1 according to Embodiment 1 of the present invention.

[Fig. 3] Fig. 3 is a flowchart illustrating an operation of the air-conditioning apparatus 1 according to Embodiment 1 of the present invention.

[Fig. 4] Fig. 4 is a flowchart illustrating an operation of the air-conditioning apparatus 1 according to Embodiment 1 of the present invention.

Description of Embodiments [0010]

Embodiments 1 to 3 of an air-conditioning apparatus according to the present invention will be described below with reference to the drawings. The present invention is not limited to Embodiments 1 to 3 described below. Further, in the following drawings including Fig. 1, the dimensional relationships between component members may be different from actual ones.

[0011]

Embodiment 1

Fig. 1 is a circuit diagram illustrating an air-conditioning apparatus 1 according to Embodiment 1 of the present invention. The air-conditioning apparatus 1 will be described with reference to Fig. 1. As illustrated in Fig. 1, the air-conditioning apparatus 1 includes a refrigerant circuit 2, bypasses 3, heat storing containers 11, and circuit switching units 12. The air-conditioning apparatus 1 further includes fans 10, temperature detecting units 13, heat medium temperature detecting units 14, and a controller 20, for example.

[0012]

The refrigerant circuit 2 connects, by pipes, a compressor 4, a plurality of indoor heat exchangers 6, a plurality of expansion units 7, and an outdoor heat exchanger 8, and allows refrigerant to flow through the refrigerant circuit 2. The refrigerant circuit 2 further includes, for example, a flow switching unit 5 and an accumulator 9 connected by pipes.

[0013]

Further, the air-conditioning apparatus 1 includes, for example, one outdoor unit 1a and two indoor units 1b connected to each other. The outdoor unit 1a is installed with the compressor 4, the flow switching unit 5, the outdoor heat exchanger 8, and the accumulator 9. Each of the two indoor units 1 b is installed with an indoor heat exchanger 6, an expansion unit 7, a fan 10, circuit switching units 12, a bypass 3, a heat storing container 11, and a temperature detecting unit 13. In Embodiment 1, the air-conditioning apparatus 1 including two indoor units 1b is illustrated as an example. The air-conditioning apparatus 1, however, may include three or more indoor units 1b.

[0014]

The compressor 4 is driven by an electric motor to compress the refrigerant. The flow switching unit 5 switches the flow direction of the refrigerant in the refrigerant circuit 2 to switch the refrigerant discharged from the compressor 4 to flow through at least one of the indoor heat exchangers 6 or the outdoor heat exchanger 8, thereby enabling execution of both a cooling operation and a heating operation. Each of the indoor heat exchangers 6 is provided in an indoor space, for example, to exchange heat between the refrigerant and indoor air, which is a heat medium.

[0015]

Each of the fans 10 is provided in the indoor space, for example, to send the indoor air to the corresponding indoor heat exchanger 6 as the heat medium that exchanges heat with the refrigerant in the indoor heat exchanger 6. Each of the expansion units 7 expands the refrigerant or reduces the pressure of the refrigerant, and has an adjustable opening degree, for example. The outdoor heat exchanger 8 is provided in an outdoor space, for example, to exchange heat between outdoor air and the refrigerant. The accumulator 9 stores an excess of the refrigerant.

[0016]

Each of the bypasses 3 bypasses at least one of the indoor heat exchangers 6. Each of the circuit switching units 12 is provided to a connecting part connecting the refrigerant circuit 2 and the corresponding bypass 3 to switch the refrigerant to flow through the refrigerant circuit 2 or the bypass 3. For example, each of the indoor units 1 b is provided with two circuit switching units 12, each of which is provided to a connecting part connecting the refrigerant circuit 2 and the corresponding bypass 3. Although Fig. 1 illustrates an example in which each of the circuit switching units 12 is a three-way valve, the circuit switching unit 12 may be a combination of plural solenoid valves.

[0017]

Each of the heat storing containers 11 is provided to the corresponding bypass 3 to store heat. The heat storing container 11 is made of a latent heat storing material, for example, but may be made of a sensible heat storing material. The heat storing container 11 may be installed outside the corresponding indoor unit 1b. Each of the temperature detecting units 13 measures the temperature of the corresponding heat storing container 11. Each of the heat medium temperature detecting units 14 measures the temperature of the indoor air as the heat medium, that is, the temperature in the indoor space. Not all of the indoor units 1 b may be provided with the bypass 3, the circuit switching units 12, and the heat storing container 11. The bypass 3, the circuit switching units 12, and the heat storing container 11 may be provided to an indoor unit 1b in which a situation not requiring the heat exchange in the indoor heat exchanger 6 is expected to occur.

[0018]

Operation modes of the air-conditioning apparatus 1 will be described below. The operation modes of the air-conditioning apparatus 1 include a cooling operation, a heating operation, a heat storing operation, and a defrosting operation. In the cooling operation, the refrigerant flows through the compressor 4, the flow switching unit 5, the outdoor heat exchanger 8, the corresponding expansion unit 7, the corresponding indoor heat exchanger 6, and the accumulator 9 in this order to exchange heat with the indoor air as the heat medium in the indoor heat exchanger 6 and thereby cool the indoor air. In the heating operation, the refrigerant flows through the compressor 4, the flow switching unit 5, the corresponding indoor heat exchanger 6, the corresponding expansion unit 7, the outdoor heat exchanger 8, and the accumulator 9 in this order to exchange heat with the indoor air as the heat medium in the indoor heat exchanger 6 and thereby heat the indoor air.

[0019]

In the heat storing operation, the refrigerant flows through the compressor 4, the flow switching unit 5, the corresponding heat storing container 11, the corresponding expansion unit 7, the outdoor heat exchanger 8, and the accumulator 9 in this order to store heat in the heat storing container 11, with the heating operation being stopped. The heat storing operation is performed in the state of a non-heating operation, in which the heating operation is not performed, for example. For example, when heating continues to be performed in one of the indoor units 1 b and is stopped in the other indoor unit 1b, the heat storing operation is performed in the other indoor unit 1 b. In the defrosting operation, the refrigerant flows through the compressor 4, the flow switching unit 5, the outdoor heat exchanger 8, the corresponding expansion unit 7, the corresponding indoor heat exchanger 6, and the accumulator 9 in this order to remove frost formed on the outdoor heat exchanger 8. [0020]

Fig. 2 is a functional block diagram illustrating the air-conditioning apparatus 1 according to Embodiment 1 of the present invention. The controller 20 will be described below. The controller 20 controls the switching operation of the circuit switching units 12. As illustrated in Fig. 2, the controller 20 includes a measuring unit 21, an arithmetic unit 22, and a storing unit 23.

[0021]

Based on signals input from the heat medium temperature detecting units 14 and the temperature detecting units 13, the measuring unit 21 measures the respective temperatures. Further, based on the results of measuring the respective temperatures, the arithmetic unit 22 performs arithmetic processing. The arithmetic unit 22 includes a switching unit 31, a rotation frequency changing unit 32, and an opening degree adjusting unit 33. Further, an arithmetic result of the arithmetic unit 22 is output to an output unit 16, such as an LED.

[0022]

In the heat storing operation, the switching unit 31 switches the corresponding circuit switching units 12 to allow the refrigerant to flow through the corresponding bypass 3. That is, when the switching unit 31 switches the circuit switching units 12 to allow the refrigerant to flow through the bypass 3, the heat storing operation of storing heat in the corresponding heat storing container 11 is performed. Further, in the defrosting operation, when the temperature of the heat storing container 11 measured by the corresponding temperature detecting unit 13 is higher than a threshold temperature, the switching unit 31 switches the circuit switching units 12 to allow the refrigerant to flow through the bypass 3. That is, when the flow switching unit 5 is switched to allow the refrigerant to flow through the outdoor heat exchanger 8, and when the switching unit 31 switches the circuit switching units 12 to allow the refrigerant to flow through the bypass 3, the defrosting operation of removing the frost formed on the outdoor heat exchanger 8 is performed.

[0023]

The threshold temperature will be described below. In the heat storing container 11 made of the latent heat storing material, a temperature equal to or higher than the temperature of the melting point of the latent heat storing material is used as the threshold temperature. The temperature of the melting point is previously stored in the storing unit 23. That is, the threshold temperature equals a value obtained by adding oc to the temperature of the melting point of the latent heat storing material. Herein, a is changeable as appropriate depending on the amount of heat stored in the heat storing container 11, and is input through an input unit 15, for example. The input unit 15 is an input device, such as a DIP switch and a remote controller.

[0024]

Further, in the heat storing container 11 made of the sensible heat storing material, a temperature equal to or higher than the temperature of the heat medium measured by the corresponding heat medium temperature detecting unit 14 is used as the threshold temperature. That is, the threshold temperature equals a value obtained by adding β to the temperature of the heat medium. Herein, β is changeable as appropriate depending on the amount of heat stored in the heat storing container 11, and is input through the input unit 15, for example.

[0025]

In the heat storing operation, the rotation frequency changing unit 32 changes the rotation frequency of the corresponding fan 10 for the heat storing operation to be equal to or lower than a threshold rotation frequency that is lower than the minimum rotation frequency of the fan 10 for the heating operation. In the heat storing operation, the opening degree adjusting unit 33 changes the opening degree of the corresponding expansion unit 7 for the heat storing operation to be equal to or less than a threshold opening degree that is less than the minimum opening degree of the expansion unit 7 for the heating operation.

[0026]

The threshold opening degree will be described below. When the indoor unit 1b performs the non-heating operation, such as the heat storing operation, the opening degree of the expansion unit 7 is determined as appropriate. In a case where the refrigerant flowing into the expansion unit 7 is two-phase gas-liquid refrigerant or a large pressure difference lies between the upstream side and the downstream side of the expansion unit 7, when the expansion unit 7 is opened to an excessive opening degree, the refrigerant mixed with air bubbles flows into the expansion unit 7 at high speed, even if no excess refrigerant is left. This configuration may cause the flowing sound of the refrigerant flowing from the indoor unit 1b. To solve this problem, threshold opening degree is set to a minimum opening degree not causing the flowing sound of the refrigerant. It is thereby possible to reduce the occurrence of the flowing sound of the refrigerant, although the amount of heat stored in the heat storing container 11 is slightly reduced.

[0027]

Operations in the operation modes of the air-conditioning apparatus 1 will be described below. The cooling operation will first be described. In the cooling operation, the compressor 4 suctions the refrigerant, compresses the refrigerant, and discharges the refrigerant in a high-temperature and high-pressure gas state. The refrigerant discharged from the compressor 4 passes through the flow switching unit

5, flows into the outdoor heat exchanger 8, and is condensed in the outdoor heat exchanger 8 through heat exchange with the outdoor air. The condensed liquid refrigerant flows into the corresponding expansion unit 7, and is reduced in pressure in the expansion unit 7 to be brought into a two-phase gas-liquid state. Then, the two-phase gas-liquid refrigerant flows into the corresponding indoor heat exchanger

6, and is evaporated in the indoor heat exchanger 6 through heat exchange with the indoor air as the heat medium. In this process, the indoor air is cooled, and thereby cooling is performed. The evaporated gas refrigerant passes through the flow switching unit 5, flows into the accumulator 9, and then is suctioned into the compressor 4.

[0028]

The heating operation will be described below. In the heating operation, the compressor 4 suctions the refrigerant, compresses the refrigerant, and discharges the refrigerant in a high-temperature and high-pressure gas state. The refrigerant discharged from the compressor 4 passes through the flow switching unit 5, flows into the corresponding indoor heat exchanger 6, and is condensed in the indoor heat exchanger 6 through heat exchange with the indoor air as the heat medium. In this process, the indoor air is heated, and thereby heating is performed. The condensed liquid refrigerant flows into the corresponding expansion unit 7, and is reduced in pressure in the expansion unit 7 to be brought into a two-phase gas-liquid state.

Then, the two-phase gas-liquid refrigerant flows into the outdoor heat exchanger 8, and is evaporated in the outdoor heat exchanger 8 through heat exchange with the outdoor air. The evaporated gas refrigerant passes through the flow switching unit 5, flows into the accumulator 9, and then is suctioned into the compressor 4.

[0029]

The heat storing operation will be described below. The heat storing operation is performed in the state of the non-heating operation, in which the heating operation is not performed, for example. The heat storing operation is performed in a stopped state, in an air-sending operation, or in a thermo-off state during the heating operation, for example. For example, when the heating continues to be performed in one of the indoor units 1 b and is stopped in the other indoor unit 1 b, the heat storing operation is performed in the other indoor unit 1 b. In the heat storing operation, the compressor 4 suctions the refrigerant, compresses the refrigerant, and discharges the refrigerant in a high-temperature and high-pressure gas state. The refrigerant discharged from the compressor 4 passes through the flow switching unit 5, flows into the corresponding bypass 3, and flows into the corresponding heat storing container

11. Thereby, the heat storing container 11 stores heat. Subsequently, the refrigerant flows into the corresponding expansion unit 7, and is reduced in pressure in the expansion unit 7 to be brought into a two-phase gas-liquid state. Then, the two-phase gas-liquid refrigerant flows into the outdoor heat exchanger 8, and is evaporated in the outdoor heat exchanger 8 through heat exchange with the outdoor air. The evaporated gas refrigerant passes through the flow switching unit 5, flows into the accumulator 9, and then is suctioned into the compressor 4.

[0030]

The defrosting operation will be described below. When the air-conditioning apparatus 1 performs the heating operation, frost may form on the outdoor heat exchanger 8. The defrosting operation is performed to remove the frost. In the defrosting operation, the compressor 4 suctions the refrigerant, compresses the refrigerant, and discharges the refrigerant in a high-temperature and high-pressure gas state. The refrigerant discharged from the compressor 4 passes through the flow switching unit 5, flows into the outdoor heat exchanger 8, and melts the frost formed on the outdoor heat exchanger 8. Then, in the outdoor heat exchanger 8, the refrigerant is condensed through heat exchange with the outdoor air. The condensed liquid refrigerant flows into the corresponding expansion unit 7. In this process, the expansion unit 7 is fully open to allow the liquid refrigerant to flow into the corresponding indoor heat exchanger 6 in the liquid state. The liquid refrigerant then flows into the indoor heat exchanger 6, and is evaporated in the indoor heat exchanger 6 through heat exchange with the indoor air as the heat medium. The evaporated gas refrigerant passes through the flow switching unit 5, flows into the accumulator 9, and then is suctioned into the compressor 4.

[0031]

Fig. 3 is a flowchart illustrating an operation of the air-conditioning apparatus 1 according to Embodiment 1 of the present invention. An operation of the airconditioning apparatus 1 according to Embodiment 1 will be described below. An operation of the air-conditioning apparatus 1 in the heat storing operation and the heating operation will first be described. As illustrated in Fig. 3, it is determined during the heating operation whether or not the temperature of the heat medium measured by the corresponding heat medium temperature detecting unit 14 meets a temperature condition for thermo-off of the corresponding indoor unit 1 b (step ST 1). When the temperature of the heat medium does not meet the temperature condition (NO at step ST 1), the procedure returns to step ST 1. Meanwhile, when the temperature of the heat medium meets the temperature condition (YES at step ST1), the indoor unit 1b is switched to the heat storing operation.

[0032]

Then, the rotation frequency changing unit 32 changes the rotation frequency of the corresponding fan 10 to be equal to or lower than the threshold rotation frequency to blow out light air (step ST2). Subsequently, the switching unit 31 switches the corresponding circuit switching units 12 to allow the refrigerant to flow through the corresponding bypass 3 (step ST3). Then, the opening degree adjusting unit 33 adjusts the opening degree of the corresponding expansion unit 7 to a slight opening degree equal to or less than the threshold opening degree (step ST4).

[0033]

Subsequently, it is determined whether or not the temperature of the heat medium measured by the heat medium temperature detecting unit 14 meets a temperature condition for thermo-on of the indoor unit 1 b (step ST5). When the temperature of the heat medium does not meet the temperature condition (NO at step ST5), the procedure returns to step ST4. Meanwhile, when the temperature of the heat medium meets the temperature condition (YES at step ST5), the indoor unit 1b is switched to the heating operation.

[0034]

Then, the switching unit 31 switches the circuit switching units 12 to allow the refrigerant to flow through the corresponding indoor heat exchanger 6 (step ST6). Subsequently, the rotation frequency changing unit 32 changes the rotation frequency of the fan 10 to the rotation frequency for the heating operation to blow out a set flow rate of air, for example (step ST7). Then, the opening degree adjusting unit 33 adjusts the opening degree of the expansion unit 7 to the opening degree for the heating operation, that is, a normal opening degree (step ST8). Then, the procedure returns to step ST1 to repeat the above-described control.

[0035]

Fig. 4 is a flowchart illustrating an operation of the air-conditioning apparatus 1 according to Embodiment 1 of the present invention. An operation of the airconditioning apparatus 1 in the defrosting operation will be described below. As illustrated in Fig. 4, when the controller 20 receives a defrosting signal, the defrosting operation starts. The rotation frequency changing unit 32 first reduces the rotation frequency of the corresponding fan 10 to blow out light air or stop the fan 10 (step ST11). Then, the opening degree adjusting unit 33 adjusts the opening degree of the corresponding expansion unit 7 to a full opening degree (step ST12).

[0036]

Subsequently, it is determined whether or not the temperature ofthe corresponding heat storing container 11 measured by the corresponding temperature detecting unit 13 is higher than the threshold temperature (step ST 13). When the temperature of the heat storing container 11 is higher than the threshold temperature (YES at step ST13), the switching unit 31 switches the corresponding circuit switching units 12 to allow the refrigerant to flow through the corresponding bypass 3 (step STM). Subsequently, the procedure returns to step ST13 at every predetermined time interval, and the defrosting operation is completed when the controller 20 receives a defrosting completion signal. Meanwhile, when the temperature of the heat storing container 11 is equal to or lower than the threshold temperature (NO at step ST13), the switching unit 31 switches the circuit switching units 12 to allow the refrigerant to flow through the corresponding indoor heat exchanger 6 (step ST15). Subsequently, when the controller 20 receives the defrosting completion signal, the defrosting operation is completed.

[0037]

Functions ofthe air-conditioning apparatus 1 according to Embodiment 1 will be described below. In the air-conditioning apparatus 1, the bypass 3 that bypasses at least one of the indoor heat exchangers 6 is provided with the heat storing container 11. This configuration allows the high-temperature and high-pressure refrigerant to flow through the heat storing container 11 in the non-heating operation.

It is therefore possible to store heat in the heat storing container 11, and thereby to reduce extra heating in the air-conditioning apparatus 1. Further, the heat stored in the heat storing container 11 is usable for another purpose. Further, it is possible to prevent the refrigerant from flowing through the indoor heat exchanger 6 in the nonheating operation, and thus to reduce accumulation of the refrigerant in the indoor heat exchanger 6.

[0038]

Further, the air-conditioning apparatus 1 includes the controller 20 having the switching unit 31 that switches the circuit switching units 12 to allow the refrigerant to flow through the bypass 3. When the switching unit 31 switches the circuit switching units 12 to allow the refrigerant to flow through the bypass 3, the heat storing operation of storing heat in the heat storing container 11 is performed. It is thus possible to allow the high-temperature and high-pressure refrigerant to flow through the heat storing container 11 in the heat storing operation. Consequently, it is possible to store heat in the heat storing container 11, and thereby to reduce the extra heating in the air-conditioning apparatus 1.

[0039]

Further, the air-conditioning apparatus 1 includes the flow switching unit 5, which switches the refrigerant discharged from the compressor 4 to flow through the indoor heat exchanger 6 or the outdoor heat exchanger 8, and the temperature detecting unit 13, which measures the temperature of the heat storing container 11. When the temperature of the heat storing container 11 measured by the temperature detecting unit 13 is higher than the threshold temperature, the switching unit 31 switches the circuit switching units 12 to allow the refrigerant to flow through the bypass 3. When the flow switching unit 5 is switched to allow the refrigerant to flow through the outdoor heat exchanger 8, and when the switching unit 31 switches the circuit switching units 12 to allow the refrigerant to flow through the bypass 3, the defrosting operation of removing the frost formed on the outdoor heat exchanger 8 is performed. In the defrosting operation, consequently, it is possible to remove the frost formed on the outdoor heat exchanger 8 with the heat stored in the heat storing container 11. It is thereby possible to reduce the time of the defrosting operation. [0040]

Furthermore, the heat storing container 11 may be made of a latent heat storing material, in which case a temperature equal to or higher than the temperature of the melting point of the latent heat storing material is used as the threshold temperature. For example, the threshold temperature equals a value obtained by adding a to the temperature of the melting point of the latent heat storing material. The latent heat storing material changes in heat amount without a change in temperature. Consequently, the threshold temperature is set to be equal to or higher than the temperature of the melting point specific to the latent heat storing material.

[0041]

Further, the air-conditioning apparatus 1 includes the heat medium temperature detecting unit 14, which measures the temperature of the heat medium that exchanges heat with the refrigerant in the indoor heat exchanger 6. The heat storing container 11 may be made of a sensible heat storing material, in which case a temperature equal to or higher than the temperature of the heat medium measured by the heat medium temperature detecting unit 14 is used as the threshold temperature. For example, the threshold temperature equals a value obtained by adding β to the temperature of the heat medium. When the temperature of the heat storing container 11 is lower than the temperature of the heat medium, it is more desirable, in the defrosting operation, to use the heat obtained from the heat medium in the indoor heat exchanger 6 than to use the heat stored in the heat storing container 11. Consequently, the threshold temperature is set to be equal to or higher than the temperature of the heat medium.

[0042]

Further, the expansion unit 7 has the adjustable opening degree. The controller 20 includes the opening degree adjusting unit 33, which adjusts, in the heat storing operation, the opening degree of the expansion unit 7 for the heat storing operation to be equal to or less than the threshold opening degree that is less than the minimum opening degree of the expansion unit 7 for the heating operation.

Further, for example, the threshold opening degree is set to the minimum opening degree not causing the flowing sound of the refrigerant. It is thereby possible to reduce the occurrence of the flowing sound of the refrigerant.

[0043]

A technique has been disclosed that allows the refrigerant discharged from the compressor 4 to flow through the accumulator 9 via the bypass 3 to reduce the flowing sound of the refrigerant. The existing technique, however, does not allow a part of the heat obtained from the compressor 4 to be used for the air-conditioning operation. By contrast, Embodiment 1 has the heat storing container 11 provided to the bypass 3 that bypasses the indoor heat exchanger 6, and thus the heat obtained from the compressor 4 flows through the indoor heat exchanger 6 or the heat storing container 11. Consequently, the entirety of the heat obtained from the compressor 4 is usable for the air-conditioning operation.

[0044]

The air-conditioning apparatus 1 further includes the fan 10 that sends the heat medium to the indoor heat exchanger 6 to exchange heat with the refrigerant in the indoor heat exchanger 6. The controller 20 includes the rotation frequency changing unit 32 that changes, in the heat storing operation, the rotation frequency of the fan 10 for the heat storing operation to be equal to or lower than the threshold rotation frequency that is lower than the minimum rotation frequency of the fan 10 for the heating operation. In the heat storing operation, consequently, it is possible to reduce the heat exchange between the heat medium and the refrigerant in the indoor heat exchanger 6.

[0045]

Further, as the heat storing container 11 is provided to each of the indoor units 1 b, it is possible to make the size of the heat storing container 11 smaller than that in a case in which one heat storing container 11 is provided for all of the indoor units 1b. Further, although Embodiment 1 illustrates an example in which the heat stored in the heat storing container 11 is used for the defrosting operation, the application of the heat is not limited to the example. For example, the heat stored in the heat storing container 11 may be discharged into the indoor space to be used for heating.

[0046]

Embodiment 2

The air-conditioning apparatus 1 according to Embodiment 2 of the present invention will be described below. In Embodiment 2, the temperature condition for thermo-off is set to be higher than that in Embodiment 1 at step ST1 in Fig. 3. For example, when a set indoor temperature set by the input unit 15 is used as the temperature condition for thermo-off, the temperature condition is set to a value obtained by adding 2 degrees Celsius to the set temperature. With this configuration, it is possible to extend the time until the indoor temperature falls to start thermo-off. Consequently, it is possible to extend the time of the heat storing operation and secure a sufficient time for storing heat in the heat storing container 11. Embodiment 2 shares the other configurations with Embodiment 1.

[0047]

Embodiment 3

The air-conditioning apparatus 1 according to Embodiment 3 of the present invention will be described below. In Embodiment 3, the process of step ST4 in Fig. 3 is omitted. That is, the opening degree of the expansion unit 7 for the heating operation is maintained without the adjustment of the opening degree of the expansion unit 7 by the opening degree adjusting unit 33. Then, when the temperature of the heat storing container 11 exceeds the threshold temperature, the process of step ST4 in Fig. 3 is performed. With this configuration, it is possible to actively store heat in the heat storing container 11 in the heat storing operation. Embodiment 3 shares the other configurations with Embodiments 1 and 2. Further, Embodiment 3 may be combined with Embodiment 2.

Reference Signs List [0048] air-conditioning apparatus 1a outdoor unit 1b indoor unit 2 refrigerant circuit 3 bypass 4 compressor 5 flow switching unit 6 indoor heat exchanger 7 expansion unit 8 outdoor heat exchanger 9 accumulator 10 fan 11 heat storing container 12 circuit switching unit 13 temperature detecting unit 14 heat medium temperature detecting unit 15 input unit 16 output unit 20 controller 21 measuring unit 22 arithmetic unit 23 storing unit 31 switching unit 32 rotation frequency changing unit 33 opening degree adjusting unit

Claims

CLAIMS [Claim 1]

An air-conditioning apparatus comprising:

a refrigerant circuit connecting, by pipes, a compressor, a plurality of indoor heat exchangers, a plurality of expansion units, and an outdoor heat exchanger, the refrigerant circuit allowing refrigerant to flow through the refrigerant circuit;

a bypass configured to bypass at least one of the plurality of indoor heat exchangers;

a heat storing container provided to the bypass to store heat; and a circuit switching unit provided to a connecting part connecting the refrigerant circuit and the bypass, the circuit switching unit being configured to switch the refrigerant to flow through the refrigerant circuit or the bypass.
[Claim 2]

The air-conditioning apparatus of claim 1, further comprising a controller including a switching unit configured to switch the circuit switching unit to allow the refrigerant to flow through the bypass, wherein when the switching unit switches the circuit switching unit to allow the refrigerant to flow through the bypass, a heat storing operation of storing heat in the heat storing container is performed.
[Claim 3]

The air-conditioning apparatus of claim 2, further comprising: a flow switching unit configured to switch the refrigerant discharged from the compressor to flow through the at least one of the plurality of indoor heat exchangers or the outdoor heat exchanger; and a temperature detecting unit configured to measure a temperature of the heat storing container, wherein when the temperature of the heat storing container measured by the temperature detecting unit is higher than a threshold temperature, the switching unit switches the circuit switching unit to allow the refrigerant to flow through the bypass, and wherein when the flow switching unit is switched to allow the refrigerant to flow through the outdoor heat exchanger, and when the switching unit switches the circuit switching unit to allow the refrigerant to flow through the bypass, a defrosting operation of removing frost formed on the outdoor heat exchanger is performed.
[Claim 4]

The air-conditioning apparatus of claim 3, wherein the heat storing container is made of a latent heat storing material, and wherein a temperature equal to or higher than a temperature of a melting point of the latent heat storing material is used as the threshold temperature.
[Claim 5]

The air-conditioning apparatus of claim 3, further comprising a heat medium temperature detecting unit configured to measure a temperature of a heat medium that exchanges heat with the refrigerant in the at least one of the plurality of indoor heat exchangers, wherein the heat storing container is made of a sensible heat storing material, and wherein a temperature equal to or higher than the temperature of the heat medium measured by the heat medium temperature detecting unit is used as the threshold temperature.
[Claim 6]

The air-conditioning apparatus of one of claims 2 to 5, wherein each of the plurality of expansion units has an adjustable opening degree, and wherein the controller includes an opening degree adjusting unit configured to adjust, in the heat storing operation, the adjustable opening degree of a corresponding one of the plurality of expansion units for the heat storing operation to be equal to or less than a threshold opening degree that is less than a minimum opening degree of the corresponding one of the plurality of expansion units for a heating operation.
[Claim 7]

The air-conditioning apparatus of one of claims 2 to 6, further comprising a fan configured to send a heat medium to the at least one of the plurality of indoor heat exchangers to exchange heat with the refrigerant in the at least one of the plurality of indoor heat exchangers, and

5 wherein the controller includes a rotation frequency changing unit configured to change, in the heat storing operation, a rotation frequency of the fan for the heat storing operation to be equal to or lower than a threshold rotation frequency that is lower than a minimum rotation frequency of the fan for a heating operation.