Air-conditioning apparatus

Abstract: In a multiroom air-conditioning apparatus, refrigerant flow between plural outdoor side units is controlled so that abnormality (lack or excess) of refrigerant amount in an outdoor side unit in operation is redressed. In addition, the output of the air-conditioning apparatus is smoothly variable (controllable) in accordance with an air-conditioning load over the whole air-conditioning load range from the minimum (zero) load to the maximum load. There are two compressors (A,B) in a first outdoor side unit (101 1 ). One is capacity-variable and the second is capacity-invariable. Both compressors have the total output ps1. A second outdoor-unit (101 2 ) has a capacity invariable compressor (C) and his output is ps2. These three compressors satisfy the following inequality: ps1ps2.

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to an air-conditioning apparatus having at least one room unit (indoor side unit) and plural outdoor side units which are connected in parallel to an inter-unit pipe extending from the room unit. 2. Description of Related Art A multiroom air-conditioning apparatus for simultaneously cooling or heating a plurality of rooms of a building has been generally known. This multiroom air-conditioning apparatus is disclosed in Japanese Laid-open Patent Application No. 2-85656, and is so constructed that a plurality of outdoor side units each having a compressor, an outdoor heat exchanger, etc. are arranged so as to be connected in parallel to an inter-unit pipe connected to each room unit. This type of multiroom air-conditioning apparatus has an advantage that realization of a large-capacity system can be promoted for such an apparatus. This type of multiroom air-conditioning apparatus has been conventionally so designed that a refrigerant flow between each outdoor side unit and each indoor side unit (room unit) is controlled through closing and opening operations of a valve, and the closing and opening operations of each valve are carried out with an individual controller which is individually provided to each outdoor side unit. In this construction, alteration of the number of outdoor side units or indoor side units to be connected necessarily requires the control operation (program) of each outdoor side unit to be individually altered, or requires each of the individual controllers itself to be replaced by another. Therefore, the conventional multiroom air-conditioning apparatus has had a disadvantage that the individual controllers can not be fixedly used without modification or replacement in any status. Further, in the conventional multiroom air-conditioning apparatus thus constructed, the same refrigerant flows in or out over plural outdoor side units which are arranged in parallel in the same system. Therefore, there occurs a problem that in a case where the refrigerant is partially trapped (naturally stocked) in an outdoor side unit located adjacently to an outdoor side unit in operation, the outdoor side unit in operation lacks the refrigerant, and a so-called "gas-lacking state" occurs in the outdoor side unit in operation. In addition, in a case where a large amount of refrigerant concentratively flows into an outdoor side unit, there occurs a problem that surplus refrigerant is liable to be trapped in an outdoor heat exchanger, etc. of the outdoor side unit. For example, when the refrigerant is trapped in the outdoor heat exchanger in a cooling operation, liquefaction of the refrigerant is depressed because a heat-discharge area is reduced. Further, in this type of multiroom air-conditioning apparatus having plural outdoor side units arranged in parallel, the air-conditioning operation is so controlled that the operation of some outdoor side units (compressors) is ceased when an air-conditioning load is reduced to a value lower than the total output of the compressors of the outdoor side units. In such a control operation, the output of the air-conditioning apparatus is required to be smoothly controlled over an air-conditioning load range of the minimum (zero) air-conditioning load to the maximum air-conditioning load. EP-A-0 410 570 discloses an air conditioner including an outdoor unit which has a variable-capacity compressor and a fixed-capacity compressor. SUMMARY OF THE INVENTION An object of this invention is to provide an air-conditioning apparatus in which the output of the air-conditioning apparatus can be smoothly controlled over the air conditioning load range from its minimum (zero) load to its maximum load. According to an aspect of this invention, in the air-conditioning apparatus having at least one indoor side unit and plural outdoor side units which are connected in parallel to an inter-unit pipe extending from the indoor side unit, at least one outdoor side unit of the plural outdoor side units is equipped with a capacity-invariable compressor and a capacity-variable compressor whose capacity is variable in accordance with an air-conditioning load. In the air-conditioning apparatus thus constructed, each of the other residual outdoor side units is equipped with a capacity-invariable compressor, and the total output ps1 of the compressor of the outdoor side unit having both of the capacity-invariable compressor and the capacity-variable compressor and the output ps2 of the compressor of the outdoor side unit having only the capacity-invariable compressor are beforehand set so as to satisfy the following equation: ps1 ≥ ps2 According to the air-conditioning apparatus thus constructed, the output of the air-conditioning apparatus can be smoothly controlled over an air-conditioning range from the minimum (zero) air-conditioning load to the maximum air-conditioning load. Still further, according to this invention, when the air-conditioning load is varied, the capacity of the capacity-variable compressor is varied in accordance with the variation of the air-conditioning load while suitably combined with the capacity of the capacity-invariable compressors, so that the output of the air-conditioning apparatus can be smoothly controlled over an extremely wide range. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a refrigerant circuit diagram of a first embodiment of this invention; Fig. 2 shows a table showing a combination of compressors; Fig. 3 shows a table showing another combination of compressors; Fig. 4 shows a table showing another combination of compressors; and Fig. 5 is a refrigerant circuit diagram of a modification of the first embodiment. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Preferred embodiments according to this invention will be described with reference to the accompanying drawings. In order to simplify the description of this invention, two outdoor side units and two indoor side units are representatively illustrated in the figures, however, the number of the outdoor side units and the number of the indoor side units are not limited to two, and any number of outdoor side units and indoor side units may be used for this invention. Fig. 1 shows an embodiment of the air-conditioning apparatus according to this invention. In Fig. 1, reference numerals 101 1 nd 101 2 represent outdoor side units, and reference numerals 103 1 and 103 2 represent indoor side units (room units). The outdoor side unit 101 1 comprises an accumulator 110 1 , a capacity-invariable compressor A, a capacity-variable compressor B whose capacity is variable in accordance with an air-conditioning load in a room, an oil (lubricating oil) separator 112 1 , a four-way change-over valve 113 1 , an outdoor heat exchanger 114 1 and an outdoor electrical expansion valve 115 1 . The outdoor side unit 101 2 comprises an accumulator 110 2 , a capacity-invariable compressor C, an oil (lubricating oil) separator 112 2 , a four-way change-over valve 113 1 , an outdoor heat exchanger 114 2 and an outdoor electrical expansion valve 115 2 . Each indoor side unit (room unit) 103 1 (103 2 ) comprises an indoor heat exchanger 134 1 (134 2 ), and an indoor electrical expansion valve (indoor mechanical valve) 135 1 (135 2 ). an inter-unit pipe comprising a gas pipe 105 and a liquid pipe 107 extends from each of the indoor side units 103 1 and 103 2 , and the outdoor side units 101 1 and 101 2 are connected in parallel to the inter-unit pipe. The oil separator 112 1 of the outdoor side unit 101 1 serves to separate lubricating oil which is contaminated in refrigerant discharged from the compressors A and B, and the separated lubricating oil is returned through a return pipe 121 1 to the compressors A and B. The return pipe 121 1 is provided with an opening and closing valve 123 1 . The oil separator 112 2 of the outdoor side unit 101 2 serves to separate lubricating oil which is contaminated in refrigerant discharged from the compressor c, and the separated lubricating oil is returned through a return pipe 121 2 to the compressor C. The return pipe 121 2 is provided with an opening and closing valve 123 2 . The return pipes 121 1 and 121 1 of the outdoor side units 101 1 and 101 2 are connected through a balance pipe 151. The balance pipe 151 serves to guide lubricating oil from a compressor having a large amount of lubricating oil to another compressor having a small amount of lubricating oil when the amount of lubricating oil is unbalanced between the compressors of the outdoor side units 101 1 and 101 2 . As shown in Fig. 2, the compressor A is a capacity-invariable compressor having 2,944 kW (4 horsepowers (ps)), the compressor B is a capacity-invariable compressor having 4,416 kW (6 horsepowers (ps)) whose capacity is variable in accordance with the air-conditioning load, and the compressor C is a capacity-invariable compressor having 7,36 kW (10 horsepowers (ps)). Here, representing the total output of the compressors of the outdoor side unit having the capacity-invariable compressor A and the capacity-variable compressor B and the output of the compressor of the outdoor side unit having only the capacity-invariable compressor C by ps1 and ps2 respectively, the relationship satisfying the following inequality is preferable in comparison of the horsepower between the compressors: ps1(A+B) ≥ ps2(C) In addition, it is preferable that compressor B(ps) ≥ compressor A(ps). In this embodiment, Ps1(A+B) = ps2(C) = 7,36 kW (10 horsepowers). In the air-conditioning apparatus having the above combination of the compressors, for example when the air-conditioning load is reduced to a value lower than the maximum output of the air-conditioning apparatus in the operation, some outdoor side units are so controlled that the operation of these outdoor side units is ceased. In such a control operation, according to this embodiment, the output of the air-conditioning apparatus is so controlled as to be smoothly variable (controllable) over the air-conditioning load range from the minimum (zero) load to the maximum load as shown in Fig. 2. That is, in order to control the output of the air-conditioning apparatus in the range of 0,736 to 4,416 kW (1 to 6 ps), the capacity-variable compressor B of the outdoor side unit 101 1 is driven, and the driving capacity thereof is controlled in its capacity-variable range. In order to control the output of the air-conditioning apparatus in the range of 5,152 to 7,36 kW (7 to 10 ps), the capacity-invariable compressor A (2,944 kW ≙ 4 ps) of the outdoor side unit 101 1 is continued to be driven while the capacity-variable compressor B of the outdoor side unit 101 1 is controlled to vary its output in the range of 2,208 to 4,416 kW (3 to 6ps). Further, in order to control the output of the air-conditioning apparatus in the range of 8,096 to 11,776 kW (11 to 16 ps), the capacity-invariable compressor C (7,36 kW ≙ 10ps) is continued to be driven while the capacity-variable compressor B of the outdoor side unit 101 1 is controlled to vary its output in the range of 0,736 to 4,416 kW (1 to 6 ps). Still further, in order to control the output of the air-conditioning apparatus in the range of 12,512 to 14,72 kW (17 to 20 ps), the capacity-invariable compressor C (7,36 kW ≙ 10ps) of the outdoor side unit 101 2 and the capacity-invariable compressor A (2,944 kW ≙ 4ps) of the outdoor side unit 101 2 are continued to be driven while the capacity-variable compressor B of the outdoor side unit 101 1 is controlled to vary its output in the range of 2,208 to 4,416 kW (3 to 6 ps). Through this operation, the output of the air-conditioning apparatus can be smoothly varied (controlled) over the range of the minimum (zero) load to the maximum (rating) load. Fig. 2 shows one example of combination of the compressors, and a large number of combinations of the compressors can be proposed as shown in tables of Figs. 3 and 4. In the tables of Figs. 3 and 4, each of INV5 (3,68 kW ≙ 5ps) and INV6 (4,416 kW ≙ 6ps) represents a compressor having only a capacity-invariable compressor. INV8 (5,888 kW ≙ 8ps) represents a compressor having a capacity-variable compressor of 3,68 kW (5ps) and a capacity-invariable compressor of 2,208 kW (3ps), and INV10 (7,36 kW ≙ 10ps) represents a compressor having a capacity-variable compressor of 4,416 kW (6ps) and a capacity-invariable compressor of 2,944 kW (4ps). For example, in Figs. 3 and 4, for the maximum output of 11,776 kW (16ps), a combination of the INV8 (5,888 kW ≙ 8ps) and the rating (capacity-invariable compressor) 5,888 kW (8ps) may be adopted. For the maximum output of 14,72 kW (20ps), a combination of the INV10 (7,36 kW ≙ 10ps) and the rating (capacity-invariable compressor) 7,36 kW (10ps) may be adopted. Further, for the maximum output of 16,928 kW (23ps), a combination of the INV5 (3,68 kW ≙ 5ps), the INV8 (5,888 kW ≙ 8ps) and the rating (capacity-invariable compressor) 7,36 kW (10ps) may be adopted. For the maximum output of 18,46 kW (25ps), a combination of the INV5 (3,68 kW ≙ 5ps), the INV10 (7,36 kW ≙ 10ps) and the rating (capacity-invariable compressor) 7,36 kW (10ps) may be adopted. According to these combinations, representing the total of the outputs of the outdoor side unit having the capacity-invariable compressor and the capacity-variable compressor by psi and representing the output of the outdoor side unit having only the capacity-invariable compressor by ps2, the following inequality is satisfied: ps1 ≥ ps2. With the combinations of the compressors which satisfy the above inequality, the output of the air-conditioning apparatus can be smoothly varied (controlled) over the whole range from the zero load to the maximum load. Fig. 5 shows a modification of this embodiment. Reference numerals 171 1 and 171 2 represent outdoor side units, and reference numerals 173 1 and 173 2 represent indoor side units. The outdoor side unit 171 1 comprises an accumulator 191 1 , a capacity-invariable compressor A, a capacity-variable compressor B, an oil (lubricating oil) separator 192 1 , an outdoor heat exchanger 193 1 , and an outdoor electrical expansion valve 194 2 . The outdoor side unit 171 2 comprises an accumulator 191 2 , a capacity-invariable compressor C, an oil separator 192 2 , an outdoor heat exchanger 193 2 , and an outdoor electrical expansion valve 194 2 . The indoor side unit 173 1 (173 2 ) comprises an indoor heat exchanger 197 1 (197 2 ), and an indoor electrical expansion valve (indoor mechanical valve) 198 1 (198 2 ). The indoor side units 173 1 and 173 2 are connected to the indoor side units 171 1 and 171 2 through an inter-unit pipe 108 comprising a high-pressure gas pipe 181, a low-pressure gas pipe 183 and a liquid pipe 185, and the pipes 181, 183 and 185 are provided with refrigerant flow passageway change-over valves a, b, c, d, e, f, g and h for enabling each of the heat exchangers 175 1 and 175 2 of the indoor side units 173 1 and 173 2 to act as a condenser or evaporator as shown in Fig. 5. That is, through the suitable switching operation of the change-over valves a, b, c, d, e, f, g and h, the refrigerant flow is varied, and one outdoor side unit 173 1 can be driven in a heating operation while the other outdoor side unit 173 2 can be driven in a cooling operation, for example. A reference numeral 201 represents a balance pipe for connecting return pipes 203 1 and 203 2 . According to this embodiment, similarly in the embodiment as shown in Fig. 1, the total of the maximum outputs of the compressors of the outdoor side unit having the capacity-invariable compressor A and the capacity-variable compressor B (ps1) and the output of the compressor of the outdoor side unit having only the capacity-invariable compressor C (ps2) are set so as to satisfy the following inequality: ps1(A+B) ≥ ps2(C). It is also preferable that compressor B (ps) ≥ compressor A (ps). According to this embodiment, like the embodiment of Fig. 1, the output of the air-conditioning apparatus can be smoothly varied (controlled) over the air-conditioning load range from the minimum (zero) load to the maximum load.

Claims: An air-conditioning apparatus including at least one indoor side unit (103 1 , 103 2 ) having an inter-unit pipe (105, 107) ex-tending therefrom, and plural outdoor side units (101 1 , 101 2 ) which are connected in parallel to the inter-unit pipe (105, 107), for controlling the number of outdoor side units (101 1 , 101 2 ) to be operated in accordance with an air-conditioning load, characterized in that at least one outdoor side unit (101 1 ) has a capacity-invariable compressor (A) and a capacity-variable compressor (B) whose capacity is variable in accordance with the air-conditioning load, and that each of residual outdoor side units (101 2 ) other than said outdoor side unit has a capacity-invariable compressor (C), and the total ps1 of outputs of said outdoor side unit (101 1 ) having said capacity-invariable compressor (A) and said capacity-variable compressor (B) and the output ps2 of each of said residual outdoor side units (101 2 ) having only said capacity-invariable compressor (C) are set so as to satisfy the following inequality: ps1 ≥ ps2. The air-conditioning apparatus as claimed in claim 1, further including control means for controlling the driving of said capacity-invariable compressor (A) and said capacity-variable compressor. (B) so that the output of said air-conditioning apparatus can be smoothly variable over an air-conditioning load range from a zero load to a maximum load. The air-conditioning apparatus as claimed in claim 1, further including a refrigerant flowing passageway (151, 201) through which said plural outdoor side units (101) are connected to one another to allow lubricating oil and/or refrigerant therebetween. The air-conditioning apparatus as claimed in claim 1, wherein each of said outdoor side units (101) comprises a compressor (A, B, C), an oil separator (112) for separating the lubricating oil and the refrigerant from each other, an outdoor heat exchanger (114) for exchanging heat between the refrigerant and the outside air, and an oil withdrawing passageway through which said oil separator (112) and said refrigerant flowing passageway (151) are intercommunicated with each other.

Inventors: KAMIMURA ICHIRO, NAGAE KOUJI, OOKUBO TAKESHI, SEKIGAMI KUNIE, SHIINA TAKAO, SHIMURA KAZUHIRO, KAMIMURA, ICHIRO, NAGAE, KOUJI, OOKUBO, TAKESHI, SEKIGAMI, KUNIE, SHIINA, TAKAO, SHIMURA, KAZUHIRO
Applicants: SANYO ELECTRIC CO, SANYO ELECTRIC CO., LTD.
Application year: 1993
Main classification: F24F11
IPC codes: F25B13, F24F11, F24F3, F25B49