MULTI-TYPE AIR-CONDITIONER

Abstract: If drain abnormality occurs, for example, an air blower 24a of an indoor unit 2 in which abnormality occurs is stopped, an electronic expansion valve 21a is fully closed, and the temperature of a heat exchanger 23a of the indoor unit 2 in which abnormality occurs is detected by a thermisor 30a. If this temperature increases, the operation of an indoor unit 3 having no drain abnormality is continued, and if this temperature does not increase, the operation of all the indoor units 2 and 3 is stopped. When a compressor 5, which has been stopped by the occurrence of abnormality, is restarted, it is determined whether or not the temperature of the indoor heat exchanger 23a decreases. If this temperature does not decrease, the operation of the other indoor unit 3 is continued, and if this temperature decreases, the operation of all the indoor units 2 and 3 is stopped.

Description: Technical Field The present invention relates to a multiple-type air conditioner in which a plurality of indoor units are connected to one outdoor unit via refrigerant pipes. Background Art FIG. 4 is a schematic view of such a multiple-type air conditioner. In this air conditioner, a plurality of, for example, two indoor units 2 and 3 are connected to one outdoor unit 1 via refrigerant pipes 4a and 4b. The outdoor unit 1 is provided with a compressor 5, and a four-way directional control valve 7 is connected to a refrigerant gas output end of the compressor 5 via an oil separator 6. The oil separator 6 is used for separating refrigerant gas into refrigerant gas and oil. The refrigerant gas is sent to the four-way directional control . valve 7 and the oil is sent to a suction pipe 8 connected to the suction end of the compressor 5. To one end of the four-way directional control valve 7 are connected two outdoor heat exchangers 9 and 10 in parallel. To these outdoor heat exchangers 9 and 10 are connected distributors 11 and 12, check valves 13 and 14, or electronic expansion valves 15 and 16, respectively. These check valves 13 and 14 or electronic expansion valves 15 and 16 are connected to a receiver 17 in common. To this receiver 17 are connected the two indoor units 2 and 3 via the refrigerant pipe 4a. The other end of the four-way directional control valve 7 is connected to the compressor 5 through an accumulator 18 and the suction pipe 8. On the other hand, the two indoor units 2 and 3 are configured so that a strainer 20a, 20b is connected to the refrigerant pipe 4a, to the strainer 20a, 20b are connected an electronic expansion valve 21a, 21b, a distributor 22a, 22b, and an indoor heat exchanger 23a, 23b, and the indoor heat exchanger 23a, 23b is connected to the refrigerant pipe 4b. The indoor unit 2, 3 is provided with an air blower (air blowing fan) 24a, 24b, and at the bottom thereof is provided a drain pan 25a, 25b for accumulating water separated by air cooling. The water accumulated in this drain pan 25a, 25b is discharged by using a drain pump 26a, 26b, or discharged naturally. In the drain pan 25a, 25b, a float switch 27a, 27b is arranged. When the drain water accumulated in either or both of the drain pans 25a and 25b overflows, the float switch 27a, 27b detects the overflow to stop all units. In such a configuration, for example, when cooling operation is performed, the refrigerant gas discharged from the compressor 5 is separated into refrigerant gas and oil by the oil separator 6, and the oil is returned to the suction pipe 8. On the other hand, the refrigerant gas is introduced to the outdoor heat exchangers 9 and 10 through the four-way directional control valve 7, and condensed in the outdoor heat exchangers 9 and 10. The refrigerant liquid condensed in the outdoor heat exchangers 9 and 10 passes through the distributors 11 and 12, the check valves 13 and 14, and the receiver 17, respectively, and is introduced to the two indoor units 2 and 3 through the refrigerant pipe 4a. Since the electronic expansion valves 15 and 16 are closed, the refrigerant liquid passes through the check valves 13 and 14. In the indoor units 2 and 3, the refrigerant liquid passes through the strainer 20a, 20b, electronic expansion valve 21a, 21b, and distributor 22a, 22b, and is introduced to the indoor heat exchanger 23a, 23b, where the refrigerant liquid is evaporated into a gaseous form. The refrigerant gas returns to the outdoor unit 1 through the refrigerant pipe 4b. It passes through the four-way directional control valve 7, accumulator 18, and suction pipe 8, and is sucked by the compressor 5 again. During the cooling operation, the indoor heat exchanger 23a, 23b in the indoor unit 2, 3 cools air, so that water in the air is separated from air and accumulates as drain water in the drain pan 25a, 25b. The water accumulated in this drain pan 25a, 25b is discharged by using the drain pump 26a, 26b, or discharged naturally. If the drain water accumulates in the drain pan 25a, 25b, and is going to overflow from the drain pan 25a, 25b, the drain abnormality is detected by the float switch 27a, 27b. Such control of drain abnormality is carried out in accordanc'e with an abnormality control flowchart shown in FIG. 5. If, in either of the indoor units 2 and 3, for example, in the indoor unit 2, the drain water overflows from the drain pan 25a and the float switch 27a is actuated, all the indoor units 2 and 3 are stopped and the abnormality is displayed on a remote control panel. In the above-described multiple-type air conditioner, however, if a plurality of indoor units, that is, two indoor units 2 and 3 are in operation and, for example, the float switch 27a of one indoor unit 2 is actuated, all the indoor units are stopped although the operation of the other indoor unit 3 can be continued. A multiple type air conditioner according to the preamble of claim 1 is known from GB-A-2 248 924. Disclosure of Invention Accordingly, an object of the present invention is to provide a multiple-type air conditioner in which of the plural indoor units, the indoor units having no abnormality caused by the overflow of drain water can continue to be operated. According to the invention the multiple-type air conditioner comprises the features of claim 1. In such a multiple-type air conditioner, when the water level in the drain pan reaches the predetermined level, the water level detection switch detects this fact and generates an abnormality signal. When abnormality occurs, the air blowing fan of the indoor unit in which abnormality occurs is stopped, the electronic expansion valve is fully closed, and it is determined whether or not the detection temperature of the temperature sensor of the indoor unit in which abnormality occurs increases. If this temperature increases, the operation of other indoor units is continued, and if this temperature does not increase, the operation of all the indoor units is stopped. Thereupon, the indoor units having no abnormality caused by the overflow of drain water can continue to be operated. Brief Description of Drawings FIG. 1 is a schematic view showing one embodiment of a multiple-type air conditioner in accordance with the present invention. FIG. 2 is a block diagram of a control system for the air conditioner. FIG. 3 is an abnormality control flowchart for the air conditioner. FIG. 4 is a schematic view of a conventional multiple-type air conditioner. FIG. 5 is an abnormality control flowchart for the conventional air conditioner. Best Mode for Carrying Out the Invention One embodiment of the present invention will be described below with reference to the accompanying drawings. The same reference numerals are applied to the same elements as those in FIG. 4, and the detailed description thereof is omitted. FIG. 1 is a schematic view of a multiple-type air conditioner. In the two indoor units 2 an 3, the indoor heat exchanger 23a, 23b is provided with a thermistor 30a, 30b as a temperature sensor. The thermistor 30a, 30b senses the temperature of the indoor heat exchanger 23a, 23b, and generates a signal according to the temperature of the indoor heat exchanger 23a, 23b. On the other hand, FIG. 2 is a block diagram of a control system. This control system is provided with an abnormality stop means 31, which receives an abnormality signal generated from the float switch 27a, 27b serving as a water level detection switch. This abnormality stop means 31 has the following function: It is determined whether or not an abnormality signal is generated from the float switches 27a and 27b. If drain water overflow abnormality occurs, this means 31 stops the air blower 24a, 24b of the indoor unit 2, 3 in which abnormality occurs, and fully closes the electronic expansion valve 21a, 21b. An operability determination means 32 has the following function: When receiving information about the occurrence of drain water overflow abnormality from the abnormality stop, means 31, the operability determination means 32 judges the operation state of the compressor 5 of the outdoor unit 1 through an output means 33. If the compressor 5 is in operation, it is determined whether or not the detection temperature of the thermistor 30a, 30b of the indoor unit 2, 3, that is, the temperature of the indoor heat exchanger 23a, 23b increases. If the detection temperature increases, the operation of the other indoor unit 3, 2 is continued. If the temperature of the indoor heat exchanger 23a, 23b does not increase, the operation of all the indoor units 2 and 3 is stopped. Also, this operability determination means 32 has a restart determination means 34. This restart determination means 34 has the following function: When the compressor 5, which has been stopped by the occurrence of drain water overflow abnormality, is restarted, this restart determination means 34 determines whether or not the temperature of the indoor heat exchanger 23a, 23b detected by the thermistor 30a, 30b decreases. If the temperature of the indoor heat exchanger 23a, 23b does not decrease, the operation of the other indoor unit 3, 2 is continued. If the temperature of the indoor heat exchanger 23a, 23b decreases, the operation of all the indoor units 2 and 3 is stopped. Next, the operation of the air conditioner configured as described above will be described in accordance with an abnormality control flowchart shown in FIG. 3. For example, when cooling operation is performed, the refrigerant gas discharged from the compressor 5 is separated into refrigerant gas and oil by the oil separator 6, as mentioned before, and the separated refrigerant gas is introduced to the outdoor heat exchangers 9 and 10 through the four-way directional control valve 7, and condensed in the outdoor heat exchangers 9 and 10. The condensed refrigerant liquid passes through the distributors 11 and 12, the check valves 13 and 14, and the receiver 17, respectively, and is introduced to the two indoor units 2 and 3 through the refrigerant pipe 4a. In the indoor units 2 and 3, the refrigerant liquid passes through the strainer 20a, 20b, electronic expansion valve 21a, 21b, and distributor 22a, 22b, and is introduced to the indoor heat exchanger 23a, 23b, where the refrigerant liquid is evaporated into a gaseous form. The refrigerant gas returns to the outdoor unit 1 through the refrigerant pipe 4b. It passes through the four-way directional control valve 7, accumulator 18, and suction pipe 8, and is sucked by the compressor 5 again. During the cooling operation, the indoor heat exchanger 23a, 23b in the indoor unit 2, 3 cools air, so that water in the air is separated from air and accumulates as drain water in the drain pan 25a, 25b. The water accumulated in this drain pan 25a, 25b is discharged by using the drain pump 26a, 26b, or discharged naturally. If the drain water accumulates in the drain pan 25a, 25b, and is going to overflow from the drain pan 25a, 25b, the float switch 27a, 27b is actuated, and a drain water overflow abnormality signal is generated. At this time, the abnormality stop means 31 determines in Step #1 whether or not an abnormality signal is generated from the float switches 27a and 27b each. As the result of this determination, if drain abnormality occurs, the abnormality stop means 31 stops, in Step #2, the operation of the air blower 24a, 24b of the indoor unit 2, 3 in which the abnormality occurs. For example, if an abnormality signal is generated from the float switch 27a, the abnormality stop means 31 stops the operation of the air blower 24a of the indoor unit 2, and, in the next step #3, fully closes the electronic expansion valve 21a. (Hereinafter, the case where drain water overflow abnormality occurs in the indoor unit 2 will be explained.) Next, when receiving information about the occurrence of drain water overflow abnormality from the abnormality stop means 31, the operability determination means 32 judges, in Step #4, the operation state of the compressor 5 of the outdoor unit 1 through an output means 33. As the result of this determination, if the compressor 5 is operated, the operability determination means 32 proceeds to Step #5, where, receiving the detection temperature of the thermistor 30a of the indoor unit 2 in which abnormality occurs, it determines whether or not the temperature of the indoor heat exchanger 23a increases. As the result of this determination, if the temperature of the indoor heat exchanger 23a of the indoor unit 2 in which abnormality occurs increases, the operability determination means 32 judges that there is no possibility of an increase in drain water of the indoor heat exchanger 23a since the cooling operation is stopped because the electronic expansion valve 21a of the indoor unit 2 in which abnormality occurs is closed. Then, the operability determination means 32 proceeds to Step #6 to stop the operation of only the indoor unit 2 in which abnormality occurs, and continue the operation of the other indoor unit 3. If it is decided in the above step #5 that the temperature of the indoor heat exchanger 23a of the indoor unit 2 in which abnormality occurs does not increase, the operability determination means 32 proceeds to Step #7 to stop all the indoor units 2 and 3, since the electronic expansion valve 21a is not fully closed, so that there is a possibility that the drain water increases and overflows if the operation is continued. On the other hand, as the result of determination of the operation state of the compressor 5 of the outdoor unit 1, if the compressor 5 is stopped, the restart determination means 34 waits for the next restart of the compressor 5 in Step #8. In the next step #9, the restart determination means 34 takes in the detection temperature of the thermistor 30a, and determines whether or not the temperature of the indoor heat exchanger 23a of the indoor unit 2 in which abnormality occurs decreases. As the result of this determination, if the temperature of the indoor heat exchanger 23a of the indoor unit 2 in which abnormality occurs does not decrease, judging that cooling operation is not performed because the electronic expansion valve 21a of the indoor unit 2 in which abnormality occurs is closed and further the drain water does not increase, the restart determination means 34 proceeds to Step #10 to stop the operation of the indoor unit 2 in which abnormality occurs and continue the operation of the other indoor unit 3. If the temperature of the indoor heat exchanger 23a of the indoor unit 2 in which abnormality occurs decreases, judging that the electronic expansion valve 21a is not fully closed, so that there is a possibility that the drain water increases and overflows if the operation is continued, the operability determination means 32 proceeds to Step #11 to stop the operation of all the indoor units 2 and 3. Thus, in the above embodiment, when the water level in the drain pan reaches a predetermined level and drain abnormality occurs, the air blower 24a of the indoor unit 2 in which abnormality occurs is stopped, the electronic expansion switch 21a is fully closed, and it is determined from the detection temperature of the thermistor 30a of the indoor unit 2 in which abnormality occurs whether or not the temperature of the indoor heat exchanger 23a increases. If this temperature increases, the operation of the other indoor unit 3 is continued, and if this temperature does not increase, the operation of all the indoor units 2 and 3 is stopped. When the compressor 5, which has been stopped by the occurrence of abnormality, is restarted, it is determined whether or not the temperature of the indoor heat exchanger 23a decreases. If this temperature does not decrease, the operation of the other indoor unit 3 is continued, and if this temperature decreases, the operation of all the indoor units 2 and 3 is stopped. Therefore, judging that there is no possibility of an increase in drain water in the indoor unit 2 in which drain abnormality occurs, of the plural indoor units 2 and 3, the operation of only the indoor unit 2 in which drain abnormality occurs is stopped, and the operation of the other indoor unit 3 is continued. Also, by determining whether the compressor 5 is operated or stopped, it can be decided whether the operation of only the indoor unit 2 in which drain abnormality occurs is stopped or the operation of all the indoor units 2 and 3 is stopped. In addition, the indoor unit 3 having no drain abnormality display can be used. Although the case where abnormality occurs in the indoor unit 2 has been explained above, the operation is the same in the case where abnormality occurs in the indoor unit 3 or in the case where three or more indoor units are provided. If drain abnormality occurs in two or more indoor units, the operation is the same except that the operation of all the indoor units in which drain abnormality occurs is stopped and the operation of the remaining indoor units is continued. The present invention is not limited to the above-described embodiment, and modifications may be made as follows. For example, the temperature sensor for detecting the temperature of the indoor heat exchanger 23a, 23b is not limited to the thermistor 30a, 30b, and other temperature detecting elements may be used. Industrial Applicability As described in detail above, according to the claims of the present invention, there can be provided a multiple-type air conditioner in which, of a plurality of indoor units, the indoor units which have no abnormality caused by the overflow of drain water can continue to be operated.

Claims: A multiple type air conditioner comprising an outdoor unit (1) having a refrigerant input (4b) and a refrigerant output (4a), and a plurality of indoor units (2, 3), each indoor unit including: an electrically controlled expansion valve (21a, 21b) and a heat exchanger (23a, 23b) coupled in series between said refrigerant input and said refrigerant output; a fan(24a,24b); a drain pan (25a, 25b) for receiving and discharging drain water generated by the heat exchanger; a temperature sensor (30a, 30b) on the heat exchanger; and a water level detection switch (27a, 27b) for generating an abnormality signal if the water level in the drain pan reaches a predetermined level; the air conditioner being characterised by further comprising abnormality stop means (31) coupled to the switch of each indoor unit and responsive to an abnormality signal from a said switch of a said indoor unit both to close the expansion valve and to stop the fan in the said indoor unit in which abnormality occurs; and operability determination means (32) coupled to each said temperature sensor and arranged in response to said abnormality signal to permit the operation of all the other indoor units if the temperature sensed by the sensor of the said indoor unit in which abnormality occurs increases, and to stop the operation of all the other indoor units if the temperature sensed by the sensor of the said indoor unit in which abnormality occurs decreases. An air conditioner according to claim 1 wherein said operability determination means further comprises restart determination means (34) for determining upon occurrence of a said abnormality signal whether a compressor (5) of the outdoor unit is or is not operative. An air conditioner according to claim 2, wherein said operability determination means is arranged to respond to said restart determination means by stopping operation of all the other indoor units if the compressor is determined to be operative and the temperature detected by the temperature sensor of the said unit in which abnormality occurs does not increase. An air conditioner according to claim 2 or claim 3 wherein if the compressor is determined to be inoperative upon occurrence of the said abnormality signal, said restart determination means is arranged to detect starting of the compressor, and said operability determination means is arranged to respond thereto by permitting operation of all the other indoor units if the temperature detected by the temperature sensor of the said unit in which abnormality occurs noes not decrease.

Inventors: SASAKURA MASAHIKO, SASAKURA, MASAHIKO, SASAKURA, Masahiko, Mitsubishi Heavy Ind., Ltd
Applicants: MITSUBISHI HEAVY IND LTD, MITSUBISHI HEAVY INDUSTRIES, LTD.
Application year: 1997
Main classification: F24F11
IPC codes: F25B13, F24F11, F24F3