Air conditioning system

Abstract: An air conditioning system for multiple rooms, comprising: an outdoor unit (1) including a variable delivery compressor (2), a four way reversing valve (3) and an outdoor heat exchange unit (4a, 4b); and two main connecting pipes (17, 18) composed of a high pressure main pipe and a low pressure main pipe to connect between outdoors and indoors; characterized in that it further comprises: a distributive controller (19) which is connected to the main connecting pipes (17, 18) to divide them into a high pressure pipe (20), a low pressure pipe (21) and a medium pressure pipe (22) therein; a plurality of indoor units (6a, 6b, 6c) which include indoor heat exchangers (8a, 8b, 8c), respectively, which are one end connected to the medium pressure pipe (22) through electronic expansion valves (12a, 12b, 12c), respectively, and which are the other end selectively connected to either one of the high pressure pipe (20) and the low pressure pipe (21), respectively; detecting means for detecting either one of refrigerant temperatures and reftrigerant pressures; and control means for carrying out a predetermined control based on such detection.

Description: The present invention relates to an air conditioning system for multiple rooms which has an outdoor unit and a plurality of indoor units connected through two refrigerant pipes, and which works as a cooling and heating concurrent multiple air conditioning system capable of carrying out a cooling operation mode and a heating operation mode in the respective indoor units selectively and individually. Referring to Figure 17, there is shown a schematic diagram showing a conventional air conditioning system for multiple rooms, which has been disclosed in e.g. Japanese Unexamined Patent Publication No. 302074/1989. In Figure 17, reference numeral 1 designates an outdoor unit. Reference numeral 2 designates a variable delivery compressor. Reference numeral 3 designates a four way reversing valve. Reference numeral 4 designates an outdoor heat exchanger. Reference numeral 5 designates an outdoor expansion valve. Reference numerals 6a, 6b and 6c designate indoor units. Reference numerals 8a, 8b and 8c designate indoor heat exchangers. Reference numeral 9 designates an outdoor fan. Reference numerals 10a, 10b and 10c designate indoor fans. Reference numeral 11 designates a header. Reference numerals 12a, 12b and 12c designate indoor first two way valves. Reference numerals 13a, 13b and 13c designate indoor second two way valves. Reference numerals 14a, 14b and 14c designate indoor first expansion valves. Reference numerals 15a, 15b and 15c designate indoor second expansion valves. Reference numeral 16 designates a two way valves. The operation of the conventional system will be described. The refrigerant which has been compressed by the compressor 2 to become a gas having high temperature and high pressure passes through the four way reversing valve 3, and is partly condensed and liquefied in the ourdoor heat exchanger 4 to become a two phase refrigerant having medium pressure. Then it is transmitted indoors through the outdoor expansion valve 5. When the indoor unit 6a is under a heating mode, and the indoor units 6b and 6c are under a cooling mode, the two phase refrigerant which has been forwarded indoors and has medium pressure passes through the indoor first two valve 12a, and is condensed and liquified in the indoor heat exchanger 8a. The refrigerant thus liquefied passes through the indoor second expansion valve 15a, and is stored as liquid in the header 11. The liquid refrigerant which has medium pressure passes through the indoor first expansion valves 14b and 14c of the indoor units 6b and 6c, and enters the respective indoor heat exchangers 8b and 8c. The refrigerant which has evaporated in the indoor heat exchangers under low pressure to gasify returns to the outdoor unit 1a through the indoor second two way valves 13b and 13c. After that, the refrigerant goes back to the compressor 2 again through the four way reversing valve 3. In this manner, a refrigerant cycle is formed. The structure of the conventional air conditioning system as stated earlier requires the capacity control for the compressor 2, the air volume control for the outdoor fan 9, the control for the outdoor expansion valve 5, the control for the outlet expansion valve 15a of the indoor unit 6a under the heating mode, and the control for the inlet expansion valves 14b and 14c of the indoor units 6b and 6c under the cooling mode. This creates a problem wherein signals required for these controls are transmitted to and fro between the indoor units and the outdoor unit to complicate these controls, failing in reliability and performance stability. It is an object of the present invention to solve the described problem, and to provide an air conditioning system for multiple rooms capable of simplifying controls, and of improving reliability and performance stability. In order to attain the said object, the present invention provides an air conditioning system for multiple rooms, comprising an outdoor unit including a variable delivery compressor, a four way reversing valve and an outdoor heat exchange unit; two main connecting pipes composed of a high pressure main pipe and a low pressure main pipe to connect between outdoors and indoors; a distribution controller which is connected to the main connecting pipes to divide them into a high pressure pipe, a low pressure pipe and a medium pressure pipe therein: a plurality of indoor units which include indoor heat exchangers, respectively, which have one end connected to the medium pressure pipe through electronic expansion valves, respectively, and which have the other end selectively connected to either one of the high pressure pipe and the low pressure pipe, respectively; detecting means for detecting either one of refrigerant temperatures and refrigerant pressures; and control means for carrying out a predetermined control based on such detection. According to a first aspect of the present invention, the detecting means is constituted by either one of pressure detecting means for detecting a pressure at a high pressure pipe and a pressure at a low pressure pipe in the outdoor unit, and temperature detecting means for detecting a condensing temperature and an operating temperature; there is provided calculation means for making calculation using either one of the following equations: wherein ΔQcomp is a capacity variable for the compressor, ΔAke is heat exchange capacity variable for the outdoor heating exchanger, A, B, C, D, A', B', C' and D' are constants, ΔPd is a controlled deviation between a desired value and a detected value at the high pressure pipe in the outdoor unit, ΔPs is a controlled deviation between a desired value and a detected value at the low pressure pipe in the outdoor unit, ΔCT is a controlled deviation between a desired value and a detected value with respect to the condensing temperature, and ΔET is a controlled deviation between a desired value and a detected value with respect to the evaporating temperature; and the control means controls the compressor, the four way reversing valve in the outdoor unit and the outdoor heat exchanger unit based on such calculation in such a manner as to reduce ΔPd and ΔPs or ΔCT and ΔET. According to another aspect of the present invention, the outdoor unit includes an outdoor fan; the outdoor heat exchange unit comprises a plurality of outdoor heat exchangers connected in parallel; at least one of the outdoor heat exchangers is provided with an on-off valve; a bypass passage is connected in parallel with the outdoor heat exchangers, and having an on-off valve therein; the detecting means is constituted by a high pressure detecting means arranged in the outdoor unit for detecting a high pressure Pd, and a low pressure detecting means arranged in the outdoor unit for detecting a low pressure Ps; and the control means finds a compressor capacity variable ΔQcomp and an outdoor unit heat exchange variable ΔAko based on a controlled deviation (ΔPd=Pd*-Pd) between a desired high pressure Pd* and the detected high pressure, and a controlled deviation (ΔPs = Ps* - Ps) between a desired low pressure Ps* and the detected low pressure, thereby to control the capacity of the compressor based on the found ΔQcomp, and also to control the heat exchange capability of the outdoor heat exchange unit by controlling the on-off valve of the at least one outdoor heat exchanger, the bypass passage on-aff valve and the outdoor fan based on the found ΔAko, in such a manner as to decrease ΔPd and ΔPs. According to a further aspect of the present invention, the outdoor unit includes an outdoor fan; the outdoor heat exchange unit comprises a plurality of outdoor heat exchangers connected in parallel; at least one of the heat exchangers is provided with an on-off valve; a bypass passage is connected in parallel with the outdoor heat exchangers, and having an on-off valve therein, the detecting means is constituted by detecting means for detecting a refrigerant condensing temperature CT and a refrigerant evaporating temperature ET in the outdoor unit and the indoor units; and the control means finds a compressor capacity variable ΔQcomp and an outdoor unit heat exchange variable ΔAko based on a controlled deviation (ΔCT=CT*-CT) between a desired condensing temperature CT* and the detected condensing temperature, and a controlled deviation (ΔET=ET*-ET) between a desired evaporating temperature ET* and the detected evaporating temperature, thereby to control the capacity of the compressor based on the found ΔQcomp, and also to control the heat exchange capability of the outdoor heat exchange unit by controlling the on-off valve of the at least one outdoor heat exchanger, the bypass passage on-off valve and the outdoor fan based on the found Ako, in such a manner as to reduce ΔCT and ΔET. In drawings: Figure 1 is a schematic diagram of an air conditioning system; Figure 2 is a schematic diagram of a first embodiment; of the air conditioning system according to the present invention; Figure 3 is a control block diagram of the first embodiment; Figure 4 is a schematic diagram of a second embodiment; Figure 5 is a control block diagram of the second embodiment; Figure 6 is a drawing of graphs to help explain the operation control of the second embodiment; Figure 7 is a schematic diagram of the air conditioning system of a third embodiment; Figure 8 is a schematic diagram showing a conventional air conditioning system for multiple rooms. The present invention will be described in detail with reference to preferred embodiments illustrated in the accompanying drawings. In figure 1, reference numeral 1 designates an outdoor unit. Reference numeral 2 designates a variable delivery compressor which is arranged in the outdoor unit 1. Reference numeral 3 designates a four way reversing valve. Reference numerals 4a and 4b designate outdoor heat exchangers. Reference numerals 6a-6c designate indoor units. Reference numeral 7 designates an accumulator. Reference numerals 8a-8c designate indoor heat exchangers. Reference numerals 12a-12c designate electronic expansion valves which are connected to each one end of the indoor heat exchangers 8a-8c. Reference numerals 17 and 18 designate main connecting pipes which connect between the outdoor unit 1 and a distributive controller 19. Reference numeral 20 designates a high pressure pipe which is arranged in the distributive controller 19. Reference numeral 21 designates a low pressure pipe. Reference numeral 22 designates a medium pressure pipe. Reference numeral 23 designates an electronic expansion valve. Reference numerals 24a-24c and 25a-25c designate electromagnetic on-off valves. The distributive controller 19 is connected to the respective indoor units 6a-6c through two branch pipes, respectively. The respective indoor units 6a-6c have the one end connected to the medium pressure pipe 22 of the distributive controller 19 through the corresponding electronic expansion valves 12a-12c, respectively. The respective indoor units have the other end connected to the high pressure pipe 20 and the low pressure pipe 21 through the electromagnetic on-off valves 24a-24c and 25a-25c of the distributive controller 19, respectively. The indoor units 6a-6c are provided with air temperature sensors 26a-26c for detecting the temperature of intake air, respectively. The indoor units 6a-6c are also provided, respectively, with first refrigerant temperature sensors 27a-27c and second refrigerant temperature sensors 28a-28c for detecting the refrigerant inlet and outlet temperature at the opposite ends of the heat exchangers 8a-8c. The indoor units 6a-6c include microcomputers 29a-29c, respectively, which work as control means to control the electronic expansion valves 12a-12c based on detection temperature signals from these sensors, and actual temperatures and set temperatures for each room. In the air conditioning system having such structure, the operations which are made when the indoor unit 6a is under a heating operation mode, and the indoor units 6b and 6c are under a cooling operation mode will be described. The refrigerant which has been compressed by the compressor 2 in the outdoor unit 1 to become a gas having high temperature and high pressure passes through the four way reversing valve 3, and is partly condensed in the outdoor heat exchangers 4a and 4b to become a two phase refrigerant. The two phase refrigerant enters the indoor distributive controller 19 through the main connecting pipe 17 having high pressure. The high pressure gaseous refrigerant which has been separated in a gas-liquid separator 30 passes through the high pressure gas pipe 20, and enters the indoor unit 6a through the electromagnetic on-off valve 25a to be used in the indoor heat exchanger 8a for heating. After that, the refrigerant enters the medium pressure pipe 22 through the electronic expansion valve 12a. The refrigerant joins with the refrigerant which has come into the medium pressure pipe 22 from a liquid layer portion in the gas-liquid separator 30 through the electronic expansion valve 23. The refrigerant thus joined enters the indoor units 6b and 6c. The refrigerant is depressurized by the electronic expansion valves 12b and 12c, and is used in the indoor heat exchangers 8b and 8c for cooling to be gasified. After that, the refrigerant joins together in the low pressure pipe 21 through the electromagnetic on-off valves 24b and 24c, comes out of the distributive controller 19, and enters the main pipe 18 which directs the refrigerant outdoors. Then, the refrigerant passes through the four way reversing valve 3 and the accumulator 7 in the outdoor unit 1, and returns to the compressor 2 again. In this manner, a refrigerant circuit for cooling and heating concurrent operation is formed. A first embodiment of the present invention will be described. Referring now to Figure 2, there is shown a schematic diagram of the refigerant circuit of the air conditioning system for multiple rooms according to the second embodiment. In the embodiment, an outdoor unit 1 includes a high pressure detector 38 and a low pressure detector 39, from which detection signals are inputted into a controller 15 as shown. The controller 15 controls compressor 2, and a four way reversing valve 3, and the heat exchange capability of an outdoor heat exchanger 4 through a fan 9. Reference numeral 7 designates an accumulator. In the refrigerant circuit, the high pressure detector 38 is arranged at a high pressure pipe in the outdoor unit 1, and the low pressure detector 39 is arranged at a low pressure pipe in the outdoor unit 1. The controller 15 receives signals from both detectors 38 and 39 to carry out the delivery control for the compressor 2, to control the heat exchange capability of the outdoor heat exchanger 4 through revolution control of the fan 9, and to perform the switching control of the four way reversing valve 3 by performing operations as to whether the indoor heat exchanger 4 is operated as a condenser to be used for a radiating source, or is operated as an evaporator to be used for a heat absorbing source. In general, if the capability of the compressor 2 is increased, a high pressure Pd rises, and a low pressure Ps falls. If the capability of the evaporator is increased, both high pressure Pd and low pressure Ps rise. To the contrary, if the capability of the condenser is increased, b6th high pressure Pd and low pressure Ps fall. The relationship among them can be quantified to obtain the following equation: wherein a,b,c,d > 0, ΔPd = Pd* - Pd, ΔPs = Ps* - Ps (Pd* and Ps* are desired values, and Pd and Ps are detected values.), ΔQ comp is a capability variable of the compressor 2, and ΔAke is a heat exchange capability variable of the outdoor heat exchanger. The equation can be modified as: Referring now to Figure 4, there is shown a schematic control block diagram wherein the equation is represented in the form of diagram. The controller 15 carries out the controls of respective parts based on the result of the operations. A condensing temperature CT and an evaporating temperature ET may be utilized instead of the high pressure Pd and the low pressure Ps. At that case, sensors for detecting the condensing temperature and the evaporating temperature are required. The equation at that case is as follows: wherein, ΔCT = CT* - CT, ΔET = ET* - ET, CT* and ET* are desired values, and CT and ET are detected values. In accordance with the embodiment, the pressures at the high pressure pipe and the low pressure pipe in the outdoor unit, or the condensing temperature and the evaporating temperature in the outdoor unit are detected, and the compressor capability variable and the heat exchange capability variable of the outdoor heat exchanger are calculated based on the controlled deviation between the detected values and the desired values. Based on the result of the calculation, the delivery control of the compressor in the outdoor unit, the control for the heat exchange capability of the outdoor heat exchanger, and the switching control of the four way reversing valve are carried out. As explained, in accordance with the second embodiment, in the air conditioning system which has a cooling and heating concurrent multiple refrigerant circuit using two pipes, the controls for the outdoor compressor and the outdoor heat exchanger can be carried out based on only the temperature or the pressure detected in the outdoor unit. No information about the indoor units is required to enable an autonomous decentralized control for the indoor units and the outdoor unit, improving reliability and stabilizing operation performance. Now, a second embodiment of the present invention will be described. Referring now to Figure 4, there is shown a schematic diagram showing the refrigerant circuit of the air conditioning system according to the second embodiment. In the third embodiment, on-off valves 26a, 26b, 27a and 27b, a bypass passage 48 and a bypass on-off valve 49 are arranged in an outdoor unit 1 as shown. The on-off valves 26a, 26b, 27a and 27b are connected to both ends of outdoor hear exchangers 4a and 4b, the bypass passage 48 is arranged in parallel with the outdoor hear exchangers 4a and 4b, and the bypass on-off valve 49 is arranged in the bypass passage 48. In addition, the reference numeral 38 designates a high pressure detector which is arranged at the refrigerant outlet side of a variable delivery compressor 2 to detect the presssure Pd of the refrigerant at that location. Reference numeral 39 designates a low pressure detector which is arranged at the refrigerant inlet side of an accumulator 7 to detect the pressure Ps of the refrigerant at that location. Reference numeral 15 designates a controller which controls a four way reversing valve 3, an outdoor fan 9, the on-off valves 26a, 26b, 27a and 27b, and the bypass on-off valve 49 based on the detection outputs from the high pressure detector 38 and the low pressure detector 39. Reference numeral 36 designates a four way reversing valve. In the air conditioning system of the third embodiment, when an indoor unit 6a is under heating mode and outdoor units are under cooling mode, a heat exchanger 8a of the indoor unit 6a works as condenser and heat exchangers 8b and 8c of the indoor units 6b and 6c function as evaporator. In the operation of the second embodiment, the heat exchange capability required for the outdoor unit 1 changes depending on a change in the capability of the indoor units 6a-6c, or the switching from the heating mode to the cooling mode and vice versa in the indoor units. This means that the heat exchange capability of the outdoor unit 1 has to be controlled accordingly. In the second embodiment, a signal indicative of the high pressure Pd detected by the high pressure detector 38, and a signal indicative of the low pressure Ps detected by the low pressure detector 39 are transmitted to the controller 15. In general, if the compressor capability is increased, the high pressure Pd rises, and the low pressure Ps falls. On the other hand, if the evaporation capability is increased, both high pressure Pd and low pressure Ps rise. To the contrary, if the condenser capability is increased, both high pressure Pd and low pressure Ps fall. If there is such a steady state that the high pressure Pd and the low pressure Ps keep certain values, it can be considered that the heat exchange capability of the indoor units is balanced against that of the outdoor unit. This means that if the heat exchange capability of the outdoor unit 1 is controlled in a way to bring the high pressure Pd and the low pressure Ps closer to a predetermined desired high presssure Pd* and a predetermined desired low pressure Ps*, respectively, an autonomous control can be realized in the outdoor unit 1 in a closed form. If a variable for the compressor capability Q comp is represented by ΔQ comp , and if a variable for the heat exchange capability Ak₀ of the outdoor hear exchanger is represented by ΔAk₀, the relationship between Pd and Ps is expressed as the following equation (2): wherein a, b, c and d are predetermined constants, and ΔPd and ΔPs are controlled deviations of the desired values, respectively, i.e. ΔPd = Pd* - Pd, ΔPs = Ps* - Ps. The equation (2) can be modified as follows: Based on ΔQ comp thus found, the delivery control of the compressor 2 is carried out. In addition, based on ΔQ comp thus found, it is determined whether the outdoor heat exchangers 4a and 4b are operated as condensers to be used for radiating source or are operated as evaporators to be used for hear absorbing source. Based on the result of this determination, four way reversing valves 3 and 36 are controlled. For example, under the operation states as stated earlier, if the heat exchange capability obtained by the previous heat exchange capability and the newly found heat exchange capability is positive, the refrigerant circuit takes such cycle that the outdoor heat exchangers 4a and 4b work as evaporators. If the heat exchange capability thus obtained is negative, the refrigerant circuit takes such cycle that the outdoor heat exchangers 4a and 4b work as condensers. Variable control for the heat exchange capability at these cycles (AKe for positive, and AKc for negative) is made by controlling the revolutions of the outdoor fan 9 and carrying out the on-off control of the on-off valves 26a, 26b, 27a and 27b, and the bypass valve 49. In other words, depending on the found heat exchange capability, the selection of the outdoor heat exchangers to be activated is made, and whether bypassing the refrigerant through the bypass passage 48 is required or not is determined. In addition, the revolution of the outdoor fan 9 is adjusted to continuously control the heat exchange capability. Referring now to Figure 5, there is shown a schematic control block diagram showing such control. For example, if the outdoor heat exchangers 4a and 4b work as condensers, whether to use both outdoor heat exchangers 4a and 4b or to use only the outdoor heat exchanger 4b, and whether to use the outdoor heat exchanger(s) while bypassing a part of the refrigerant through the bypass passage 48 are determined depending on a required heat exchange capability. According to such determination, the on-off controls of the on-off valves 26a, 26b, 27a and 27b, and the bypass valve 49 are made, and the revolution of the outdoor fan 9 is controlled. Referring now to Figure 6, there is shown the relationship between the revolution of the outdoor fan and the heat exchange capability of the condenser(s) at the respective cases. The case wherein both outdoor heat exchangers 4a and 4b are used has the greatest value for AKc, with the case wherein only the outdoor heat exchanger 4b is used, and the case wherein the bypass passsage 48 is used for bypass following in that order. In addition, the values for AKc successfully change with respect to the revolutions of the outdoor fan 9 in the respective cases. Such controls can be adopted to realize an autonomous capability control in the outdoor unit 1. Referring now to Figure 7, there is shown a schematic diagram of the air conditioning system of a third embodiment wherein a refrigerant condensing temperature CT and a refrigerant evaporating temperature ET in the whole system are detected instead of the high pressure Pd and the low pressure Ps to control the outdoor unit 1. Reference numeral 34 designates refrigerant temperature sensors which are arranged in indoor units 6a-6c, respectively. Reference numeral 35 designates microcomputers which control electronic expansion valves 12a-12c based on temperatures detected by the refrigerant temperature sensors 34 to carry out autonomous controls of the indoor units 6a-6c. Reference numeral 46 designates a temperature sensor which is arranged on an outdoor heat exchanger 4b. In this embodiment, the greatest value among the temperatures detected by the refrigerant temperature sensors 34 and the temperature sensor 46 is taken as the condensing temperature CT, and the least value is taken as the evaporating temperature ET. A controlled deviation ΔCT between the condensing temperature CT and a desired condensing temperature CT*, and a controlled deviation ΔET between the evaporating temperature ET and a desired evaporating temperature ET* are found, respectively. Like the control based on the high pressure Pd and the low pressure Ps, ΔQ comp and ΔAK₀ are found from the following equation: The heat exchange capability may be controlled in a similar manner. Although in that case there is e.g. a manner wherein the highest temperature and the lowest temperature are selected by'the microcomputers 35 or the like in the indoor units, and these temperatures are transmitted to the outdoor unit to be compared to the detection temperature in the outdoor unit, at least one signal transmission line is required between the indoor units and the outdoor unit. However, the provision of the temperature sensors offers advantage over that of the pressure detectors in terms of cost. The air conditioning system according to the second embodiment detects the high pressure Pd and the low pressure Ps by the pressure sensors in the form of real time measurement, and calculates the controlled deviation ΔPd and ΔPs to the desired high pressure Pd* and the desired low pressure Ps* in the refrigeration cycle. In addition, the system finds a product by multiplying the constant matrix and takes the calculation result as Based on such result, the heat exchange capability of the outdoor heat exchangers is controlled. As explained, the second embodiment has such arrangement that the controls of the compressor, the outdoor heat exchangers and the four way reversing valve in the outdoor unit are made based on detection of only the high pressure and the low pressure in the outdoor unit. This arrangement enables the autonomous decentralized controls in the indoor units and the outdoor unit, offering an advantage in that reliability is improved and operation performance is stabilized. As in the third embodiment, the condensing temperature and the evaporating temperature, instead of the high pressure and the low pressure, in the refrigerant cycle may be detected for the autonomous decentralized controls to stabilize the operation of the outdoor unit.

Claims: An air conditioning system for multiple rooms, comprising: an outdoor unit (1) including a variable delivery compressor (2), a four way reversing valve (3) and an outdoor heat exchange unit (4a, 4b); two main connecting pipes (17, 18) composed of a high pressure main pipe and a low pressure main pipe to connect between outdoors and indoors; a distributive controller (19) which is connected to the main connecting pipes (17, 18) to divide them into a high pressure pipe (20), a low pressure pipe (21) and a medium pressure pipe (22) therein; a plurality of indoor units (6a, 6b, 6c) which include indoor heat exchangers (8a, 8b, 8c), respectively, which are at one end connected to the medium pressure pipe (22) through electronic expansion valves (12a, 12b, 12c), respectively, and which are at the other end selectively connected to either one of the high pressure pipe (20) and the low pressure pipe (21), respectively; detecting means for detecting either one of refrigerant temperatures and refrigerant pressures; and control means for carrying out a predetermined control based on such detection; characterized in that: the detecting means is constituted by either one of pressure detecting means (38, 39) for detecting a pressure at a high pressure pipe and a pressure at a low pressure pipe in the outdoor unit (1), and temperature detecting means for detecting a condensing temperature and an evaporating temperature; there is provided calculation means for making calculation using either one of the following equations: wherein ΔQcomp is a capacity variable for the compressor, ΔAke is a heat exchange capacity variable for the outdoor heat exchanger, A, B, C, D, A', B', C' and D' are constants, ΔPd is a controlled deviation between a desired value and a detected value at the high pressure pipe in the outdoor unit (1), ΔPs is a controlled deviation between a desired value and a detected value at the low pressure pipe in the outdoor unit (1), ΔCT is a controlled deviation between a desired value and a detected value with respect to the condensing temperature, and ΔET is a controlled deviation between a desired value and a detected value with respect to the evaporating temperature; and the control means (15) controls the compressor (2), the four way reversing valve (3) in the outdoor unit (1) and the outdoor heat exchange Unit (4) based on such calculation in such a manner as to reduce ΔPd and ΔPs or ΔCT and ΔET. An air conditioning system for multiple rooms, comprising: an outdoor unit (1) including a variable delivery compressor (2), a four way reversing valve (3) and an outdoor heat exchange unit (4a, 4b); two main connecting pipes (17, 18) composed of a high pressure main pipe and a low pressure main pipe to connect between outdoors and indoors; a distributive controller (19) which is connected to the main connecting pipes (17, 18) to divide them into a high pressure pipe (20), a low pressure pipe (21) and a medium pressure pipe (22) therein; a plurality of indoor units (6a, 6b, 6c) which include indoor heat exchangers (8a, 8b, 8c), respectively, which are at one end connected to the medium pressure pipe (22) through electronic expansion valves (12a, 12b, 12c), respectively, and which are at the other end selectively connected to either one of the high pressure pipe (20) and the low pressure pipe (21), respectively; detecting means for detecting either one of refrigerant temperatures and refrigerant pressures; and control means for carrying out a predetermined control based on such detection; characterized in that: the outdoor unit (1) includes an outdoor fan (9); the outdoor heat exchange unit comprises a plurality of outdoor heat exchangers (4a, 4b) connected in parallel; at least one of the outdoor heat exchangers (4a, 4b) is provided with an on-off valve; a bypass passage (48) is connected in parallel with the outdoor heat exchangers (4a, 4b), and having an on-off valve (49) therein; the detecting means is constituted by a high pressure detecting means (38) arranged in the outdoor unit (1) for detecting a high pressure Pd, and a low pressure detecting means (39) arranged in the outdoor unit (1) for detecting a low pressure Ps; and the control means finds a compressor capacity variable ΔQcomp and an outdoor unit heat exchange variable ΔAko based on a controlled deviation (ΔPd=Pd*-Pd) between a desired high pressure Pd* and the detected high pressure, and a controlled deviation (ΔPs=Ps*-Ps) between a desired low pressure Ps* and the detected low temperature, thereby to control the capacity of the compressor (2) based on the found ΔQcomp' and also to control the heat exchange capability of the outdoor heat exchange unit (4a, 4b) by controlling the on-aff valve of the at least one outdoor heat exchanger (4a or 4b), the bypass passage on-off valve (49) and the outdoor fan (9) based on the found ΔAko, in such a manner as to decrease ΔPd and ΔPs. An air conditioning system for multiple rooms, comprising: an outdoor unit (1) including a variable delivery compressor (2), a four way reversing valve (3) and an outdoor heat exchange unit (4a, 4b); two main connecting pipes (17, 18) composed of a high pressure main pipe and a low pressure main pipe to connect between outdoors and indoors; a distributive controller (19) which is connected to the main connecting pipes (17, 18) to divide them into a high pressure pipe (20), a low pressure pipe (21) and a medium pressure pipe (22) therein: a plurality of indoor units (6a, 6b, 6c) which include indoor heat exchangers (8a, 8b, 8c), respectively, which are at one end connected to the medium pressure pipe (22) through electronic expansion valves (12a, 12b, 12c), respectively, and which are at the other end selectively connected to either one of the high pressure pipe (20) and the low pressure pipe (21), respectively; detecting means for detecting either one of refrigerant temperatures and refrigerant pressures; and control means for carrying out a predetermined control based on such detection; characterized in that: the outdoor unit (1) includes an outdoor fan (9); the outdoor heat exchange unit comprises a plurality of outdoor heat exchangers (4a, 4b) connected in parallel; at least one of the heat exchangers (4a, 4b) is provided with an on-off valve; a bypass passage (48) is connected in parallel with the outdoor heat exchangers (4a, 4b), and having an on-off valve (49) therein; the detecting means is constituted by detecting means (34, 46) for detecting a refrigerant condensing temperature CT and a refrigerant evaporating temperature ET in the outdoor unit (1) and the indoor units (6a, 6b, 6c); and the control means finds a compressor capacity variable ΔQcomp and an outdoor unit heat exchange variable ΔAko from the equation: based on a controlled deviation (ΔCT=CT*-CT) between a desired condensing temperature CT* and the detected condensing temperature CT, and a controlled deviation (ΔET=ET*-ET) between a desired evaporating temperature ET* and the detected evaporating temperature ET, where a' - d' are constants, thereby to control the capacity of the compressor (2) based on ΔQcomp, and also to control the heat exchange capability of the outdoor heat exchange unit (4a, 4b) by controlling the on-offvalve of the at least one outdoor heat exchanger (4a or 4b), the bypass passage on-offvalve (49) and the outdoor fan (9) based on AAko, in such a manner as to reduce ΔCT and ΔET.

Inventors: KASAI TOMOHIKO MITSUBISHI DENK, MATSUOKA FUMIO MITSUBISHI DENK, NAKAMURA TAKASHI MITSUBISHI DE, TAKATA SHIGEO MITSUBISHI DENKI, TANI HIDEKAZU MITSUBISHI DENKI, KASAI, TOMOHIKO, MITSUBISHI DENKI K.K., MATSUOKA, FUMIO, MITSUBISHI DENKI K.K., NAKAMURA, TAKASHI, MITSUBISHI DENKI K.K., TAKATA, SHIGEO, MITSUBISHI DENKI K.K., TANI, HIDEKAZU, MITSUBISHI DENKI K.K.
Applicants: MITSUBISHI ELECTRIC CORP, MITSUBISHI DENKI KABUSHIKI KAISHA
Application year: 1991
Main classification: F25B13
IPC codes: F25B41, F24F3, F25B13