GB2516140A

GB2516140A - Air-conditioning apparatus

Info

Publication number: GB2516140A
Application number: GB1406479.4A
Authority: GB
Inventors: Takaharu Nakamura; Kunihiro Inui
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2013-05-09
Filing date: 2014-04-10
Publication date: 2015-01-14
Anticipated expiration: 2034-04-10
Also published as: MX343906B; GB2516140B; CN203869265U; CN104142007A; JP2014219162A; MX2014005618A; GB201406479D0; JP5959473B2; CN104142007B

Abstract

An air-conditioning apparatus 1 includes an outdoor unit 2 comprising a compressor 4 and a first heat exchanger 5, at least one indoor unit 3 comprising a second heat exchanger 6 and a second heat exchanger temperature detecting unit 20, and a controller 10. The first heat exchanger is configured to exchange heat between a refrigerant and outdoor air and the second heat exchanger is configured to exchange heat between the refrigerant and indoor air. The second heat exchanger temperature detecting unit is configured to detect a temperature of the second heat exchanger. The controller includes an adjusting unit configured to adjust a rotation speed of the compressor on the basis of the temperature of the second heat exchanger detected by the second heat exchanger temperature detecting unit when the rotation speed of the compressor is equal to an upper limit of the rotation speed of the compressor and the temperature of the second heat exchanger is higher than a reference temperature. The reference temperature may be calculated on the basis of the indoor temperature detected by an indoor temperature detecting unit 19, and/or from a temperature set by remote control 23.

Description

[Name of Document] DESCRIPTION

[Title of Invention] AIR-CONDITIONING APPARATUS

[Technical Field]

[0001] The present invention relates to an air-conditioning apparatus in which a plurality of indoor units are connected to a single outdoor unit.

[Background Art]

[0002] A multi-air-conditioning apparatus has a configuration in which various types of indoor units are connectable to a single outdoor unit. In order to provide comfortable spaces, the multi-air-conditioning apparatus needs to operate the outdoor unit to which those indoor units having different device characteristics are connected in a controllable manner. There has been a problem that, if the multi-air-conditioning apparatus continuously performs a cooling operation over a long period of time in a high humidity indoor environment, dew forms on the casing of each of the indoor units and water droplets of the dew fall inside the room from the casing.

[0003] The combination of the indoor units used in the multi-air-conditioning apparatus is freely selectable by a purchaser of the product. In a stage where the product appears on the market, it is unclear how the indoor units are combined and used. To address condensation in various combinations of indoor units, characteristics of condensation are estimated in advance for all of the indoor units connectable to the outdoor unit, and the rotation speed of the compressor is controlled on the basis of the estimation. Specifically, the maximum rotation speed of the compressor is regulated with reference to an operation start time in accordance with the model of an indoor unit having the lowest resistance to condensation in the lineup of connectable indoor units freely set for each outdoor unit.

[0004] Patent Literature 1 discloses a multi-room air-conditioning apparatus "in which a refrigeration cycle is formed by connecting an outdoor unit including a compressor and an outdoor heat exchanger and at least one or more indoor units each including an indoor heat exchanger through a refrigerant branch unit including a motor-operated expansion valve for controlling a refrigerant disposed between the outdoor unit and the indoor units, a model capacity rank of each of the indoor(s) connected through the refrigerant branch unit and a load level of a room corresponding to the indoor unit are transmitted to the refrigerant branch unit, and the load level of the indoor unit is also transmitted to the outdoor unit." [0005] Patent Literature 2 discloses an air-conditioning apparatus "in which different kinds of indoor units and outdoor units are connectable in any combination, each of the outdoor units includes model code storing means for storing an outdoor unit model code representing its model and means for transmitting the outdoor unit model code to the indoor unit(s) when the outdoor unit is connected to the indoor unit(s), each of the indoor units includes storing means for storing control data for all of the connectable outdoor unit(s), identifying means for receiving the outdoor unit model code transmitted from each of the connected outdoor unit(s) and identifying the model of the outdoor unit, and transmitting means for selecting the control data corresponding to the outdoor unit from the storing means in accordance with the model of the outdoor unit identified by the identifying means and transmitting the selected control data to the outdoor unit, and the outdoor unit further includes means for receiving the control data transmitted from the transmitting means in the indoor unit and performing an air-conditioning operation on the basis of the control data." [0006] Patent Literature 3 discloses a multi-air-conditioning apparatus being "a heat-pump multi-air-conditioning apparatus including an outdoor unit and a plurality of indoor units that are connected to the outdoor unit and that are independently controllable in operation, the multi-air-conditioning apparatus being operable in condensation preventing operation mode selected in a predetermined condition in cooling operation or dehumidifying operation, in the condensation preventing operation mode, a predetermined upper limit rotation speed being set for a compressor and the multi-air-conditioning apparatus being operated while a fan in each of the indoor units is maintained at a rotation speed when the mode is selected." [Citation List] [Patent Literature] [0007] [Patent Literature 1] Japanese Unexamined Patent Application Publication No. 8-121 846 (claim 1) [Patent Literature 2] Japanese Unexamined Patent Application Publication No. 6-21 3496 (claim 1) [Patent Literature 3] Japanese Unexamined Patent Application Publication No. 2006-234296 (claim 1)

[Summary of Invention]

[Technical Problem] [0008] A conventional air-conditioning apparatus aims to prevent condensation on an indoor unit in cooling operation by controlling the rotation speed of a compressor in an outdoor unit such that a temperature of air blown from the indoor unit does not excessively decrease. However, to connect an indoor unit having a low resistance to condensation in the conventional air-conditioning apparatus, it is necessary to set the maximum rotation speed of the compressor at a low value in accordance with that indoor unit. Thus, even when only an indoor unit having a high resistance to condensation, that is, an indoor unit in which condensation does not easily occur is connected to the outdoor unit, because the rotation speed of the compressor is regulated more than necessary for that connected indoor unit, its cooling capacity may not be sufficiently achieved.

[0009] The present invention is made in light of the above issues and can provide an air-conditioning apparatus capable of performing an appropriate cooling operation by switching a method of controlling a compressor when an indoor unit having a low resistance to condensation is not connected.

[Solution to Problem] [0010] An air-conditioning apparatus according to the present invention includes a compressor, a first heat exchanger, a second heat exchanger, an indoor temperature detecting unit, a second heat exchanger temperature detecting unit, and a controller. The compressor is disposed in an outdoor unit. The first heat exchanger is disposed in the outdoor unit and configured to exchange heat between a refrigerant and outdoor air. The second heat exchanger is disposed in an indoor unit and configured to exchange heat between the refrigerant and indoor air. The indoor temperature detecting unit is configured to detect an indoor temperature. The second heat exchanger temperature detecting unit is configured to detect a temperature of the second heat exchanger. The controller is configured to control the compressor. The controller includes an adjusting unit configured to adjust a rotation speed of the compressor on the basis of the temperature of the second heat exchanger detected by the second heat exchanger temperature detecting unit when the rotation speed of the compressor is equal to an upper limit of the rotation speed of the compressor and the temperature of the second heat exchanger is higher than a reference temperature calculated on the basis of the indoor temperature detected by the indoor temperature detecting unit.

[Advantageous Effects of Invention] [0011] According to the present invention, the rotation speed of the compressor is altered on the basis of performance and characteristics of an indoor unit and in consideration of an initial setting and an operation status. That enables an appropriate cooling operation while suppressing dew condensation on the casing of the indoor unit and falling of water droplets inside a room even when the cooling operation continues for a long time in a high humidity indoor environment.

[Brief Description of Drawings]

[0012] [Fig. 1] Fig. 1 is a diagram of connection in an air-conditioning apparatus 1 according to Embodiment 1.

[Fig. 2] Fig. 2 is a flowchart that illustrates how the air-conditioning apparatus 1 operates according to Embodiment 1.

[Fig. 3] Fig. 3 illustrates information transmission from indoor units 3, 3a, 3b, and 3c to an outdoor unit 2 according to Embodiment 1.

[Fig. 4] Fig. 4 illustrates information transmission from the outdoor unit 2 to the indoor units 3, 3a, 3b, and 3c according to Embodiment 1.

[Fig. 5] Fig. 5 is a flowchart that illustrates how the air-conditioning apparatus 1 operates according to a modification of Embodiment 1.

[Description of Embodiments]

[0013] Embodiment 1 of the present invention will be described below with reference to the drawings. The present invention is not limited to Embodiment 1 described below. In the drawings described below, including Fig. 1, the relationships among the sizes of the components may be different from actual ones.

[0014] Embodiment 1 Fig. 1 is a diagram of connection in an air-conditioning apparatus 1 according to Embodiment 1. The air-conditioning apparatus 1 will be described with reference to Fig. 1. As illustrated in Fig. 1, three indoor units 3, 3a, and 3b are connected to a single outdoor unit 2 in one example of the air-conditioning apparatus 1. The outdoor unit 2 includes a compressor 4, an outdoor-unit heat exchanger 5 (first heat exchanger), and an outdoor air-sending device 7. The compressor 4 compresses a refrigerant entering the air-conditioning apparatus 1.

That compression increases the temperature of the refrigerant. The outdoor-unit heat exchanger 5 exchanges heat between the refrigerant and outdoor air. That heat exchange causes the refrigerant to condense or evaporate. The outdoor air-sending device 7 blows the outdoor air having exchanged heat with the refrigerant to outside the room. The air-conditioning apparatus 1 includes a controller 10 configured to control the compressor 4 and various refrigerant circuit devices included in the air-conditioning apparatus. The controller 10 includes an upper limit determining unit 11 and an adjusting unit 12.

[0015] Each of the indoor units 3, 3a, and 3b includes an indoor-unit heat exchanger 6 (second heat exchanger) and an indoor air-sending device 8. The indoor-unit heat exchanger and the indoor air-sending device in each of the indoor units 3a and 3b are not illustrated in Fig. 1. The indoor-unit heat exchanger 6 exchanges heat between the refrigerant and indoor air. That heat exchange causes the refrigerant to evaporate and condense. The indoor air-sending device 8 blows the indoor air having exchanged heat with the refrigerant to inside the room. The indoor-unit heat exchanger 6 includes therein an indoor-unit heat exchanger temperature detecting unit 20 configured to detect a temperature of the indoor-unit heat exchanger 6. The indoor-unit heat exchanger temperature detecting unit 20 can include a main detecting unit 20a and a sub-detecting unit 20b assisting the main detecting unit 20a in detection performed thereby, for example. An indoor temperature detecting unit 19 configured to detect an indoor temperature can be disposed in the vicinity of the indoor-unit heat exchanger 6, for example. A remote control 23 is provided for each of the three indoor units 3, 3a, and 3b. The remote control 23 is used in setting any indoor temperature therefrom.

[0016] Next, the case where the air-conditioning apparatus 1 performs a cooling operation is described. First, a refrigerant with a temperature increased by compression performed by the compressor 4 passes through a four-way valve 13 and enters the outdoor-unit heat exchanger 5. The outdoor-unit heat exchanger exchanges heat between the refrigerant and the outdoor air. As a result, the refrigerant condenses. The outdoor air having exchanged heat with the refrigerant is sent by the outdoor air-sending device 7 to outside the room. The condensed refrigerant passes through a strainer 14 and an LEV 15 and reaches a receiverS. The receiverS is a tank for storing the refrigerant. The strainer 14 removes moisture, foreign matter, or the like from the refrigerant by filtering the refrigerant through a filter, using a desiccant, or through other means. The refrigerant having passed through the receiver 9 passes through a valve 16 and enters each of the indoor units 3, 3a, and 3b.

[0017] The refrigerant entering the indoor unit 3 is described below. The refrigerant entering the indoor unit 3 passes through the LEV 17 and reaches the indoor-unit heat exchanger 6. The indoor-unit heat exchanger 6 exchanges heat between the refrigerant and the indoor air. That heat exchange causes the refrigerant to evaporate. The indoor air cooled by exchanging heat with the refrigerant is blown into the room by the indoor air-sending device 8. That cools the inside of the room. The evaporated refrigerant enters the outdoor unit 2 again, passes through a muffler 21 having the noise reducing function, a valve 22, and the four-way valve 13 and enters the compressor 4. In such a way, the refrigerant circulates through a path extending through the compressor 4, the outdoor-unit heat exchanger 5, the receiver 9, and the indoor-unit heat exchanger 6 inside the air-conditioning apparatus 1. The refrigerant entering the indoor unit 3a from the outdoor unit 2 passes through an LEV 1 7a. The refrigerant entering the indoor unit 3b from the outdoor unit 2 passes through an LEV 17b.

[0018] Next, how the air-conditioning apparatus 1 operates according to Embodiment 1 is described. Fig. 2 is a flowchart that illustrates how the air-conditioning apparatus 1 operates according to Embodiment 1. Fig. 3 illustrates information transmission from the indoor units 3, 3a, 3b, and 3c to the outdoor unit 2 according to Embodiment 1. Fig. 4 illustrates information transmission from the outdoor unit 2 to the indoor units 3, 3a, 3b, and 3c according to Embodiment 1. Fig. 5 is a flowchart that illustrates how the air-conditioning apparatus 1 operates according to a variation of Embodiment 1. As illustrated in Fig. 2, first, the upper limit determining unit 11 in the controller 10 identifies the resistance to condensation of each of the indoor units 3, 3a, and 3b on the basis of type information and performance range information for the indoor units 3, 3a, and 3b transmitted from the indoor units 3, 3a, and 3b, respectively (step Si).

Table 1 shows examples of the type information and performance range information retained in each of the indoor units.

[0019]

[TABLE 1]

Model Name of Indoor Unit Model Code Performance Code a A0 01 b Al 02 c A2 03 [0020] As shown in Table 1, for example, for the indoor unit with the model name a, its type information, that is, model code is A0 and its performance range information, that is, performance code is 01. For the indoor unit with the model name b, its type information, that is, model code isAl and its performance range information, that is, performance code is 02. For the indoor unit with the model name c, its type information, that is, model code isA2 and its performance range information, that is, performance code is 03. The upper limit determining unit 11 identifies the resistance to condensation for each of the indoor units 3, 3a, and 3b on the basis of the above-described information. The upper limit determining unit 11 alters the maximum rotation speed of the compressor 4 set in advance in the outdoor unit 2 in consideration of both the degree of the identified resistance to condensation and the number of operated indoor units. That is, the upper limit determining unit 11 determines the upper limit of the rotation speed of the compressor 4 in accordance with the degree of the identified resistance to condensation (step S2) A method for altering the maximum rotation speed (upper limit value of the rotation speed) is shown in Table 2.

[0021]

[TABLE 2]

For Time (t) after Start of After Elapse of Time (t) Operation after Start of Operation Combination Pattern of Combination Pattern of ___________ _________________ Fan Speeds in Indoor Unit Fan Speeds in Indoor Unit Number of Sum of Operated Performance Codes A B C A B C Indoor Units of Indoor Units _______ _______ _______ _______ _______ _______ 1 01-05 60Hz 50Hz 50Hz 50Hz 40Hz 40Hz _________ 06-10 70Hz 60Hz 60Hz 60Hz 50Hz 50Hz 2 06-10 _____ 70Hz _____ _____ 60Hz _____ 3. . 4. . [0022] As shown in Table 2, the maximum rotation speed (upper limit of the rotation speed) of the compressor 4 is altered on the basis of the number of operated indoor units, the sum of the performance codes of the indoor units, and the combination pattern of the fan speeds in the indoor units. The sum of the performance codes of the indoor units is the sum of the performance codes of actually operated indoor units among all of the connected indoor units. As the combination patterns of the fan speeds in the indoor units, three combination patterns A, B, and C are set. The combination pattern A is the one in which all of the fan speeds is high speed (Hi), combination pattern B is the one in which the fan speeds are mixture of Hi and intermediate speed (M), and combination pattern C is the one in which all of the fan speeds is low speed (Lo). When the number of operated indoor units is one, the three combination patterns of A where the fan speed is Hi, B where the fan speed is M, and C where the fan speed is Lo, are used.

[0023] Alteration of the maximum rotation speed of the compressor 4 is described below using the case where three indoor units (indoor unit a, indoor unit b, and indoor unit c) are connected to a single outdoor unit as an example. The performance code of the indoor unit a is 01, that of the indoor unit b is 03, and that of the indoor unit c is 04. In a multi-air-conditioning apparatus in which the indoor units having the above-described specifications are connected to the outdoor unit, when the indoor unit a is inactive (OFF) and the indoor units b and c are active (ON), the sum of the performance codes of the indoor units is 07, which is obtained by addition of 04 (indoor unit c) to 03 (indoor unit b). At that time, if the set fan speed or the fan speed determined by automatic setting (Auto) of the indoor unit b is Hi and that of the indoor unit c is M, the combination pattern of the fan speeds in the indoor units is mixture of Hi and M, which is therefore B. In that case, when the number of operated indoor units is two, the sum of the performance codes of the indoor units is 07, that is, in the range of 06-10, and the combination pattern of the fan speeds in the indoor units is B, Table 2 reveals that the maximum rotation speed (upper limit of the rotation speed) of the compressor 4 is set at 70 Hz for time t after the start of the operation and that the maximum rotation speed (upper limit of the rotation speed) of the compressor 4 is changed to 60 Hz after the elapse of the time t. In that manner, the value of the maximum rotation speed of the compressor 4 set for the period until the time t elapses from the state of the operation and that set for the period after the elapse of the time t can be set at different values.

[0024] Next, in the state where the upper limit of the rotation speed of the compressor 4 is determined, as illustrated in Figs. 3 and 4, the air-conditioning apparatus 1 is operated while the operation ON/OFF state and the set fan speed of each of the indoor units 3, 3a, and 3b are communicated (step S3). The number of the indoor units connected to the outdoor unit 2 is not limited to three.

Four indoor units 3, 3a, 3b, and 3c may be connected, as illustrated in Figs. 3 and 4, and more than four units may also be connected.

[0025] The adjusting unit 12 in the controller 10 determines whether the rotation speed of the compressor 4 is equal to the upper limit determined at step S2 (step S4). When the rotation speed of the compressor 4 is lower than the upper limit, the rotation speed of the compressor 4 can be raised, and therefore the air-conditioning apparatus 1 is operated while the operation ON/OFF state and the set fan speed of each of the indoor units 3, 3a, and 3b are communicated again (NO at step S4). When the rotation speed of the compressor 4 is equal to the upper limit, processing proceeds to the next step (YES at step S4).

[0026] At the next step, a reference temperature is calculated. The reference temperature is calculated on the basis of the indoor temperature detected by the indoor temperature detecting unit 19 (step S5). The reference temperature can also be found from the difference between the set indoor temperature in an operated indoor unit whose operation is instructed from the remote control 23 and the temperature of the indoor-unit heat exchanger 6 detected by the indoor-unit heat exchanger temperature detecting unit 20 using a previously stored temperature difference table (step S5a in Fig. 5). The reference temperature can also be calculated using a hygrometer and temperature indicator placed as a detecting unit 18 (not illustrated). The reference temperature can also be determined on the basis of the difference between the indoor temperature and the set temperature.

[0027] At the next step, the adjusting unit 12 determines whether the temperature of the indoor-unit heat exchanger 6 detected by the indoor-unit heat exchanger temperature detecting unit 20 is higher than the reference temperature calculated at step S5 or step S5a (step S6). When the temperature of the indoor-unit heat exchanger 6 is equal to or lower than the reference temperature, because a further reduction in the temperature of the indoor-unit heat exchanger 6 would promote condensation on the indoor units 3, 3a, and 3b, the air-conditioning apparatus 1 is operated while the operation ON/OFF state and the set fan speed of each of the indoor units 3, 3a, and 3b are communicated again (NO at step S6). When the temperature of the indoor-unit heat exchanger 6 is higher than the reference temperature, processing proceeds to the next step (YES at step S6). As described above, in addition to the operation ON/OFF state and the set fan speed, the temperature of the indoor-unit heat exchanger 6 is communicated between the outdoor unit 2 and each of the indoor units 3, 3a, and 3b, as illustrated in Figs. 3 and 4.

[0028] As described above, when the rotation speed of the compressor 4 is equal to the upper limit determined at step S2 (YES at step S4) and the temperature of the indoor-unit heat exchanger 6 is higher than the reference temperature (YES at step S6), the upper limit of the rotation speed of the compressor 4 is raised (step S7). The rotation speed of the compressor 4 is also increased on the basis of the temperature of the indoor-unit heat exchanger 6 such that the temperature of the indoor-unit heat exchanger 6 approaches a temperature targeted for the indoor-unit heat exchanger 6 determined from the operation state of each of the indoor units 3, 3a, and 3b (hereinafter referred to as target temperature) (step SB).

[0029] As described above, the magnitude of the increase in which the rotation speed of the compressor 4 is to be increased is determined by the difference between the target temperature and the temperature of the indoor-unit heat exchanger 6 detected by the indoor-unit heat exchanger temperature detecting unit 20. When the temperature of the indoor-unit heat exchanger 6 is higher than the reference temperature, even if the temperature of the indoor-unit heat exchanger 6 is reduced to the reference temperature, the indoor air can be further cooled while condensation on the indoor units 3, 3a, and 3b is suppressed. Accordingly, with the condition that the temperature of the indoor-unit heat exchanger 6 is higher than the reference temperature, the upper limit of the rotation speed of the compressor 4 is increased and the rotation speed itself is increased. If the set temperature set by a user of the air-conditioning apparatus 1 is high, it is not necessary to increase the cooling capacity of the air-conditioning apparatus 1, therefore processing goes back to step S3, and the operation continues.

[0030] The rotation speed of the compressor 4 is increased at step SB, as described above, and the compressor 4 is operated with that increased rotation speed (step S9). Then, it is determined whether the temperature of the indoor-unit heat exchanger 6 is lower than the target temperature (temperature targeted for the indoor-unit heat exchanger 6) (step Sb). When the temperature of the indoor-unit heat exchanger 6 is equal to or higher than the target temperature, processing goes back to step S9 to cause the temperature of the indoor-unit heat exchanger 6 to reach the target temperature, and the operation of the compressor 4 with the increased rotation speed continues (NO at step S 10).

When the temperature of the indoor-unit heat exchanger 6 is lower than the target temperature, because it is not necessary to lower the temperature of the indoor-unit heat exchanger 6, processing proceeds to the next step (YES at step Sb). That is, the rotation speed of the compressor 4 is reduced (step 511). In the state where the compressor 4 is operated at the reduced rotation speed, processing goes back to step S3, and the operation of the air-conditioning apparatus 1 continues while the operation ON/OFF state and the set fan speed of each of the indoor units 3, 3a, and 3b are communicated again.

[0031] As described above, when the temperature of the indoor-unit heat exchanger 6 is higher than the reference temperature, the air-conditioning apparatus 1 is operated in the state where the compressor 4 is operated at the increased rotation speed. Accordingly, the air-conditioning apparatus 1 can detect the operation state of each of the indoor units 3, 3a, and 3b connected to the outdoor unit 2 without including additional detecting means in the indoor units 3, 3a, and 3b other than the indoor temperature detecting unit 19 and the indoor-unit heat exchanger temperature detecting unit 20, and can perform an appropriate cooling operation, for example, an operation at the lowest blowing temperature in a range where condensation does not occur while suppressing condensation on the casing of each of the indoor units 3, 3a, and 3b and falling of water droplets inside a room. The present invention can prevent condensation simply by including the indoor temperature detecting unit 19 and the indoor-unit heat exchanger temperature detecting unit 20 in a multi-air-conditioning apparatus in which various models of indoor units are connected, and thus can also be effective in reducing the cost of the models being developed.

[Reference Signs List] [0032] 1: air-conditioning apparatus, 2: outdoor unit, 3, 3a, 3b, 3c: indoor unit, 4: compressor, 5: outdoor-unit heat exchanger (first heat exchanger), 6: indoor-unit heat exchanger (second heat exchanger), 7: outdoor air-sending device, 8: indoor air-sending device, 9: receiver, 10: controller, 11: upper limit determining unit, 12: adjusting unit, 13: four-way valve, 14: strainer, 15: LEV, 16: valve, 17, 17a, 17b: LEV, 18: detecting unit, 19: indoor temperature detecting unit, 20: indoor-unit heat exchanger temperature detecting unit (second heat exchanger temperature detecting unit), 20a: main detecting unit, 20b: sub-detecting unit, 21: muffler, 22: valve, 23: remote control.