JP2010164270A - Multiple chamber type air conditioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To optimize refrigerant circulation amount to reduce cost without depending on a pressure sensor during cooling operation at low outside air temperature in a multiple chamber type air conditioner including a plurality of indoor units. <P>SOLUTION: During cooling operation (S1), when the low outside air temperature state is determined as a result of detection of the outside air temperature by an outside air temperature sensor and when temperature of a heat exchanger of the operating indoor unit is below a predetermined value (S4, S5), an opening of an expansion valve of the stopped indoor unit is temporarily increased (S5) to store specific amount of a refrigerant within an indoor heat exchanger of the stopped indoor unit, to sense and prevent excessive decline in low pressure side pressure and a risk of liquid return. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a multi-room type air conditioner in which a plurality of indoor units are connected to a single outdoor unit, and more specifically, a multi-room type air that performs stable operation during cooling operation, particularly at a low outside air temperature. It provides a harmony machine.

  In recent years, there has been a growing demand for cooling throughout the year in order to cool the exhaust heat of computers, etc. even when there are no people in the room, and the development of a multi-room type air conditioner that air-conditions multiple rooms has been developed. It has been demanded.

Conventionally, in this type of multi-room air conditioner, when only one room is cooled, as a means for optimizing the refrigeration cycle, an outdoor unit is used depending on the evaporation capacity of the indoor units for one room. Decrease the condensing performance by lowering the fan speed or lowering the compressor frequency. However, especially in a multi-room air conditioner, especially at low outdoor temperatures, the outdoor condensing capacity is still excessive, the refrigerant is excessive in the outdoor side, and the amount of refrigerant circulating in the cycle is more than the optimum amount. And the low pressure (indoor unit pressure) falls below a predetermined range. When the outside air temperature falls below 0 ° C (low outside air temperature state), the low-pressure side pressure falls below a predetermined range, that is, the indoor heat exchanger temperature becomes 0 ° C or less, and the indoor unit may be frosted. There is. Therefore, in order to prevent such a situation and continue the operation so that the pressure does not become a predetermined value or less, means for correcting the expansion valve in the opening direction is known, but the circulation amount of the liquid refrigerant is excessive. Therefore, it circulates to the compressor outside the room and enters a liquid compression state. Therefore, in such a case, from the viewpoint of compressor protection, an operation for stopping the compressor is performed to avoid this (see, for example, Patent Document 1).
JP 2007-278665 A

  However, in the conventional configuration, when the low-pressure side pressure becomes a predetermined value or less, control is performed to stop the compressor once. This is because the operation capacity of the compressor corresponding to the one-chamber operation is started. It will be a movement that repeats the stop. In such a situation, a stable operation cannot be performed, and the refrigeration cycle is not established. Furthermore, since the cycle state is monitored only by the pressure sensor, even if it can cope with securing the above-mentioned low pressure side pressure, it cannot cope with the risk of increasing the liquid compression, from the viewpoint of compressor protection. Development of means for simultaneously avoiding liquid compression while suppressing the pressure drop on the low pressure side has been an issue.

  Moreover, in the conventional structure, in order to detect a pressure, the pressure sensor was used, and it had the subject that the cost of components which comprises a refrigerating cycle starts. Furthermore, the cost of the component is also a problem when a refrigerant unnecessary for operation is temporarily stored in the outdoor unit of the multi-room air conditioner to prevent liquid compression.

In order to solve the above-described conventional problems, a multi-room air conditioner of the present invention includes an outdoor unit including a compressor, an outdoor heat exchanger, and an outdoor air temperature sensor that detects an outdoor air temperature. Each of the indoor heat exchangers provided therein and an indoor heat exchanger temperature sensor for detecting the temperature of the indoor heat exchanger, wherein the outdoor air temperature sensor detects the outside air temperature during cooling operation. When it is determined that the temperature is low and the heat exchanger temperature of the operating indoor unit is less than a predetermined value, the expansion valve opening of the stop indoor unit is temporarily increased. It is characterized by.

  As a result, excess liquid refrigerant circulating in the refrigeration cycle can be temporarily retained in the stop indoor unit, making it easy to adjust the refrigerant to the optimum refrigerant amount according to the operation status of the multi-chamber air conditioner. Therefore, both the protection from the pressure drop and the avoidance of the liquid compression can be achieved, the unnecessary compressor stop operation can be reduced, and the stable operation can be continued. In addition, the use of a temperature sensor makes it possible to keep component costs low.

  The multi-chamber air conditioner of the present invention accurately monitors the behavior of the refrigerant during cooling operation at low outside air temperature to prevent the low-pressure side from dropping below a predetermined pressure and the liquid refrigerant is excessive. A multi-room air conditioner that can be avoided and is excellent in stability and safety can be provided.

  1st invention is equipped with the compressor, outdoor heat exchanger, and outdoor temperature sensor which detects outdoor temperature in an outdoor unit, the indoor heat exchanger provided in each of several indoor units, and the said indoor heat exchange It is a multi-room air conditioner equipped with an indoor heat exchanger temperature sensor that detects the temperature of the cooler, and during cooling operation, the outside air temperature sensor detects the outside air temperature to determine that the temperature is low. And when the heat exchanger temperature of a driving | running indoor unit is less than predetermined value, it is supposed that the expansion valve opening degree of a stop indoor unit will be increased temporarily.

  As a result, excess liquid refrigerant circulating in the refrigeration cycle can be temporarily retained in the stop indoor unit, making it easy to adjust to the optimum refrigerant amount, and ensuring protection by ensuring low pressure and avoiding liquid compression Thus, unnecessary compressor stop operation can be reduced, and stable operation can be continued.

  The second invention is characterized in that, in particular, in the first invention, when there are a plurality of stop indoor units, the opening degree of the expansion valve of the stop indoor unit is temporarily increased sequentially.

  As a result, the liquid refrigerant is self-evaporated from the stop indoor unit and returned to the cycle by effectively using the plurality of stop indoor units not operating as an evaporator and dispersing and retaining the liquid refrigerant therein. The time to come can be extended and more stable operation can be continued.

  In a third aspect of the present invention, particularly in the first or second aspect of the present invention, an intake temperature sensor for detecting the intake temperature of the compressor is further provided, and the temperature difference between the indoor heat exchanger temperature and the intake temperature of the compressor is monitored. When the temperature difference is lower than a predetermined value for a predetermined time, the expansion valve opening of the stop indoor unit is temporarily increased.

  This makes it possible to recognize and avoid that the liquid refrigerant is returning to the outdoor compressor before the device is stopped, without using an expensive pressure sensor. More stable operation can be continued without the need for

  The fourth invention is the outdoor heat exchanger temperature sensor that detects the temperature of the outdoor heat exchanger and the outdoor heat exchanger outlet temperature that detects the temperature of the outlet of the outdoor heat exchanger, particularly in the first to third inventions. A sensor is further provided to detect the temperature difference between the temperature of the outdoor heat exchanger and the temperature of the outlet of the outdoor heat exchanger, and when the temperature difference tends to increase, the expansion valve opening of the indoor unit that is temporarily stopped It is characterized in that it has a function of temporarily increasing.

As a result, it is possible to recognize and avoid that the liquid refrigerant is increasing on the indoor unit side more accurately and in advance, and continue stable operation that does not require the equipment to be stopped. Can do.

  A fifth invention is characterized in that, in particular, in the first to fourth inventions, the expansion valve opening degree of the stop indoor unit is temporarily increased and the indoor fan of the stop indoor unit is operated at a low speed.

  This increases the overall refrigeration cycle evaporation capacity in a way that temporarily complements the evaporation capacity of the stop indoor unit, suppresses excessive pressure drop on the low-pressure side, and evaporates the liquid refrigerant before returning it to the cycle. And more stable operation can be continued.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 shows a block diagram of a multi-room type air conditioner according to the present invention. A plurality of indoor units 4a, 4b, and 4c (three in FIG. 1) are connected to one outdoor unit 2 by refrigerant piping. It is connected. The outdoor unit 2 is provided with a compressor 5 sequentially connected by a refrigerant pipe, a four-way valve 6 and an outdoor heat exchanger 10, and an outdoor fan 18 that sends air to the outdoor heat exchanger 10. Furthermore, a discharge temperature sensor 7, an intake temperature sensor 8, and an outside air temperature sensor 9 for detecting the temperature in each part are provided. Also, an outdoor heat exchanger temperature sensor 11 and an outdoor heat exchanger outlet temperature sensor for detecting the refrigerant condensation temperature of the outdoor heat exchanger 10 during cooling or dehumidifying operation, or the refrigerant evaporation temperature of the outdoor heat exchanger 10 during heating operation. 12 is installed. Then, outdoor expansion valves 13a, 13b, and 13c through which refrigerant flows into the indoor units 4a, 4b, and 4c are provided, and the indoor heat exchangers 14a that are sequentially connected to the indoor units 4a, 4b, and 4c by refrigerant pipes, 14 b and 14 c are provided, and the plurality of indoor units 4 a, 4 b and 4 c are connected in parallel to the outdoor unit 2.

  The indoor units 4a, 4b, and 4c are provided with indoor fans 26a, 26b, and 26c that send air to the indoor heat exchangers 14a, 14b, and 14c.

  Furthermore, the indoor heat exchanger temperature sensor 28a for detecting the refrigerant evaporation temperature of the indoor heat exchangers 14a, 14b, 14c during the cooling or dehumidifying operation or the refrigerant condensation temperature of the indoor heat exchangers 14a, 14b, 14c during the heating operation, 28b, 28c, and indoor heat exchanger outlet temperature sensors 29a, 29b, 29c for detecting the temperature of the gas refrigerant in the indoor unit during the cooling operation, and an indoor temperature sensor for detecting the indoor temperature sucked into the indoor fans 26a, 26b, 26c 30a, 30b, and 30c are provided.

  The operation and action of the multi-room air conditioner of the present invention configured as described above will be described below.

  During the cooling operation, the refrigerant flows in the arrow direction shown in FIG. 1, and the refrigerant discharged from the compressor 6 is sent to the indoor units 4 a, 4 b, 4 c through the outdoor unit 10.

  The expansion mechanisms on the refrigeration cycle are outdoor expansion valves 13a, 13b, and 13c. The discharge temperature of the compressor 5 is detected by the discharge temperature sensor 8 in order to make the opening degree appropriate. That is, the degree of superheat consisting of the difference between the temperature of the indoor heat exchangers 14a, 14b, 14c and the temperature of the gas refrigerant is adjusted while the outdoor expansion valve is adjusted to an opening degree that optimizes the entire refrigeration cycle based on the detected discharge temperature. Each indoor unit 4a, 4b, 4c is controlled so that it may become a predetermined value.

Here, when only the indoor unit 4a is operating, the expansion valve 13a is adjusted as described above, and the expansion valves 13b and 13c of the indoor units 4b and 4c stopped at this time are completely closed. The operation frequency of the compressor 5 is determined by the total number of loads recognized by the number of operating units of each indoor unit and the set temperature of each room and the difference between the indoor temperature sensors 30a, 30b, and 30c. During the heating operation, the four-way valve 6 is switched so that the refrigerant discharged from the compressor 5 is sent to the outdoor unit 10 through the indoor units 4a, 4b, and 4c.

  Next, the operation when the outside air temperature and the indoor heat exchanger temperature are detected in a state where the cooling operation is performed as the entire multi-room air conditioner will be described with reference to the flowchart of FIG. In the following, the indoor units 4a and 4b are described, but the same control is performed even when the same selection is made in 4c and other indoor units not shown.

  First, when the indoor unit 4a starts the cooling operation (step S1), it is determined how many units are operating, and it is determined whether there is a stopped indoor unit (step S2).

  Next, temperature measurement is performed by the outside air temperature sensor 9 and the indoor heat exchanger temperature sensor 28a (step S3). At this time, if the outdoor temperature is lower than the predetermined value, it is determined that the low outdoor air temperature state is present. Furthermore, when the predetermined time has elapsed and the indoor heat exchanger temperature continues to be lower than the predetermined value (step S4), the low-pressure side (indoor unit) pressure approaches the lower limit of the compressor usage range. The expansion valve 13a of the indoor unit 4a that is operating is corrected in the opening direction with respect to the current expansion valve opening (step S5). Further, it is monitored whether or not the temperature of the indoor heat exchanger temperature sensor 28a operating has risen to a predetermined temperature after a predetermined time has passed (step S6), and if not, the expansion of the stopped indoor unit 4b is performed. The valve 13b is operated in the opening direction by a predetermined value, continued for a predetermined time, and then closed again (step S7).

  If the indoor heat exchanger temperature still does not rise even when the opening of the expansion valve of the operating indoor unit is increased, that is, if it is determined that the excessive liquid refrigerant state has not been resolved, Is retracted to the indoor unit that is temporarily stopped, thereby preventing liquid refrigerant from returning to the compressor and preventing liquid compression.

  As a result, excess liquid refrigerant circulating in the refrigeration cycle can be temporarily retained in the stop indoor unit, making it easy to adjust the optimum refrigerant amount, achieving both low-pressure protection and avoiding liquid compression. The required stop operation of the compressor can be reduced, and stable operation can be continued.

(Embodiment 2)
FIG. 3 shows a control flowchart in the present embodiment. In the present embodiment, particularly in the first embodiment, when there are a plurality of stop indoor units, after the opening and closing operation of the expansion valve is performed once, and the indoor heat exchanger temperature is still smaller than the predetermined value, The expansion valves of the other stop indoor units are sequentially opened and closed.

  The operation when detecting the outside air temperature and the indoor heat exchanger temperature in a state where the cooling operation is performed as the entire multi-room air conditioner will be described with reference to the flowchart of FIG. Note that the content described in the first embodiment will be omitted.

  First, steps S1 to S7 operate in the same manner as in the first embodiment. After that, a predetermined time has passed, and it is monitored again whether the temperature of the operating indoor heat exchanger temperature sensor 28a rises to the predetermined temperature (step S8), and continues to be less than the predetermined value. In the case (step S9), the expansion valve 13c of the indoor unit 4c, which is another stop indoor unit, operates in the opening direction by a predetermined value, continues for a predetermined time, and then closes again (step S10).

As a result, the liquid refrigerant can be dispersed and retained in the stop indoor unit that is not operating as an evaporator, and the time for the liquid refrigerant to self-evaporate from the stop indoor unit and return to the cycle can be extended. The liquid compression of the refrigerant in the compressor can be prevented. In addition, since the refrigerant amount can be adjusted over a wide range by sequentially opening and closing the expansion valves of the other stopped indoor units, it is possible to operate with the optimum refrigerant amount according to the indoor unit being operated. Thereby, since the low-pressure side pressure can be ensured, more stable operation can be continued.

(Embodiment 3)
FIG. 4 shows a control flowchart in the present embodiment. In this embodiment, in particular, in the first or second embodiment, after the correction is made in the opening direction of the expansion valve of the stop indoor unit, the opening / closing operation of the expansion valve is further controlled according to the degree of suction superheat.

  The operation when detecting the outside air temperature and the indoor heat exchanger temperature in a state where the cooling operation is performed as the entire multi-room air conditioner will be described with reference to the flowchart of FIG. It should be noted that the contents described in the above embodiments will be omitted and described.

  First, steps S1 to S6 operate in the same manner as in the second embodiment. Then, the indoor heat exchanger temperature and the suction detected by the indoor heat exchanger temperature sensor 28a installed in the indoor unit 4a and the suction temperature sensor 8 that detects the pipe temperature connected to the compressor 5 of the outdoor unit 2 The suction superheat degree is calculated from the temperature difference (step S7). If the suction superheat degree continues below a predetermined value even after a predetermined time has elapsed (step S8), the expansion valve 13b of the stopped indoor unit 4b is operated in the opening direction by a predetermined value, After continuing for a predetermined time, it is closed again (step S9).

  At this time, when the degree of suction superheat is low, it is determined that the amount of refrigerant evaporated in the indoor heat exchanger is small and the amount of liquid refrigerant is large. When the state where the suction superheat degree is below a certain value is continued, it can be detected that the liquid refrigerant is returning to the compressor.

  In the present embodiment, it is possible to keep the cost of the component parts low by monitoring the refrigerant state in the refrigeration cycle not by the pressure sensor but by the temperature sensor.

(Embodiment 4)
FIG. 5 shows a control flowchart in the present embodiment. In the present embodiment, particularly in the first to third embodiments, after the opening and closing operation of the expansion valve of the stop indoor unit is performed, the difference temperature between the outdoor heat exchanger temperature and the outdoor heat exchange outlet temperature is further monitored. Thus, the opening and closing of the expansion valve is further controlled by the change in the differential temperature.

  Figure 5 shows the operation when the outdoor heat exchanger temperature and the outdoor heat exchanger outlet temperature are detected, and these temperatures are detected and compared a predetermined number of times while the multi-room air conditioner is in cooling operation as a whole. This will be described with reference to the flowchart of FIG. Note that the contents described in the above embodiment are omitted.

  First, steps S1 to S6 operate in the same manner as in the third embodiment. Next, when the condensed refrigerant, which should have a certain amount in the outdoor heat exchanger 10, flows out to the indoor unit 4a more than necessary, the refrigerant is condensed and supercooled, and the outdoor heat exchanger outlet temperature decreases. It becomes a trend. At this time, the temperature difference detected by the outdoor heat exchanger temperature sensor 11 and the outdoor heat exchanger outlet temperature sensor 12 tends to increase. Although it is normally normal, if the outside air temperature is low and the indoor heat exchanger temperature remains stable for a predetermined time, the temperature difference does not increase.

Here, in order to calculate the difference between the outdoor heat exchanger temperature and the outdoor heat exchanger outlet temperature, a predetermined time interval and the number of detections (here, n times) are set in advance, and the outdoor heat is calculated by the number of times. The exchanger temperature and the outdoor heat exchange outlet temperature are detected (step S7). It is determined whether or not the detected temperature tends to increase by comparing each of the detected temperatures n-1 and n-th (step S8). If the detected temperature is detected to be small even within the predetermined number of times, it is determined that the condensed refrigerant is still present in the outdoor heat exchanger, the process returns to step S3, and monitoring is continued. repeat. If it is confirmed that the temperature difference between the detected temperatures tends to increase, it is determined that there is a high risk that the condensed refrigerant flows out beyond the evaporation capacity of the indoor unit and the liquid refrigerant returns to the compressor. Then, the expansion valve 13b of the stopped indoor unit 4b is operated in the opening direction by a predetermined value, continued for a predetermined time, and then closed again (step S9).

  Thereby, it is possible to recognize that liquid refrigerant is not accumulated in the outdoor heat exchanger, and to detect in advance that the liquid refrigerant is increasing on the indoor unit side. Thus, in this Embodiment, liquid state can be prevented beforehand by detecting a refrigerant | coolant state beforehand, and the stable driving | operation without a stop of an apparatus can be performed.

  Moreover, since the refrigerant state can be recognized on the outdoor unit side, not on the temperature change on the indoor unit side, the refrigeration cycle is not established even in the indoor unit where various capacities, connection pipe lengths, and installation states are assumed. The state can be judged only by the temperature sensor difference. This makes it possible to recognize that there is a risk of a liquid return state to the compressor at a low cost and with no accuracy without using a pressure sensor, and to avoid it.

(Embodiment 5)
FIG. 6 shows a control flowchart in the present embodiment. In this embodiment, particularly in the first to fourth embodiments, the expansion valve of the stop indoor unit is opened and closed, and the fan of the stop indoor unit is operated for a predetermined time.

  The operation when detecting the outside air temperature and the indoor heat exchanger temperature in a state where the cooling operation is performed as the entire multi-room air conditioner will be described with reference to the flowchart of FIG. It should be noted that the contents described in the above embodiments will be omitted and described.

  First, steps S1 to S6 operate in the same manner as in the first embodiment.

  Next, the expansion valve 13b of the stopped indoor unit 4b is operated in the opening direction by a predetermined value. At this time, the fan 26b of the indoor unit 4b is operated at a low speed (step S7). After this operation is continued for a predetermined time, the fan 26b is stopped and the expansion valve 13b is closed again.

  As a result, it is possible to increase the overall refrigeration cycle evaporation capacity in a form that temporarily complements the evaporation capacity of the stopped indoor unit, and fundamentally avoids the situation where the low pressure on the indoor unit side is too low. it can.

  As described above, in the present embodiment, it is possible to suppress an excessive decrease in the low-pressure (indoor unit side) pressure, evaporate the liquid refrigerant and return it to the cycle, and it is not necessary to stop the equipment for safety. Stable operation can be continued.

  In this embodiment, when the indoor fan is operated at a low speed, it is limited to a case where it is detected in advance that there is no occupant in the room by ID management or the like of the occupant. It does not interfere with the provision of comfortable air conditioning.

As described above, the operation control method of the multi-room air conditioner according to the present invention can adjust the liquid refrigerant flow rate to the indoor heat exchanger without depending on the pressure sensor, and the low pressure does not decrease too much. Since a refrigeration cycle can be established by avoiding unnecessary protection operations, it can be applied to applications such as refrigerant flow control of commercial and store multi-room air conditioners equipped with an expansion valve in an indoor unit.

Block diagram of the multi-room air conditioner of the present invention The flowchart in the 1st Embodiment of this invention Flowchart in the second embodiment of the present invention Flowchart in the third embodiment of the present invention Flowchart in the fourth embodiment of the present invention Flowchart in the fifth embodiment of the present invention

2 Outdoor unit 4a, 4b, 4c Indoor unit 5 Compressor 6 Four-way valve 7 Discharge temperature sensor 8 Suction temperature sensor 9 Outside air temperature sensor 10 Outdoor heat exchanger 11 Outdoor heat exchanger temperature sensor 12 Outdoor heat exchanger outlet temperature sensor 13a, 13b, 13c Outdoor expansion valves 14a, 14b, 14c Indoor heat exchanger 18 Outdoor fans 26a, 26b, 26c Indoor fans 28a, 28b, 28c Indoor heat exchanger temperature sensors 29a, 29b, 29c Indoor heat exchanger outlet temperature sensors 30a, 30b, 30c Indoor temperature sensor

Claims (5)

The outdoor unit includes a compressor, an outdoor heat exchanger, and an outdoor air temperature sensor that detects an outdoor air temperature, and detects the temperature of the indoor heat exchanger provided in each of the plurality of indoor units and the indoor heat exchanger. A multi-room air conditioner equipped with an indoor heat exchanger temperature sensor,
During cooling operation, when it is determined that the outside air temperature is detected by the outside air temperature sensor and the heat exchanger temperature of the operating indoor unit is lower than a predetermined value, the expansion valve of the stop indoor unit A multi-room air conditioner characterized in that the opening degree is temporarily increased. 2. The multi-room air conditioner according to claim 1, wherein when there are a plurality of stop indoor units, the expansion valve opening of the stop indoor unit is temporarily increased sequentially. An intake temperature sensor for detecting the intake temperature of the compressor is further provided to monitor the temperature difference between the indoor heat exchanger temperature and the intake temperature of the compressor, and the state where the temperature difference is less than a predetermined value is continued for a predetermined time. When it does, the multi-chamber type air conditioner according to claim 1 or 2, wherein the expansion valve opening of the stop indoor unit is temporarily increased. An outdoor heat exchanger temperature sensor for detecting the temperature of the outdoor heat exchanger and an outdoor heat exchanger outlet temperature sensor for detecting the temperature of the outlet of the outdoor heat exchanger are further provided, and the temperature of the outdoor heat exchanger and the outdoor heat exchanger are further provided. 4. The expansion valve opening degree of the stop indoor unit is temporarily increased when the temperature difference from the temperature of the outlet of the engine is detected and the temperature difference tends to increase. The multi-room air conditioner according to item 1. The multi-chamber air according to any one of claims 1 to 4, wherein the expansion valve opening of the stop indoor unit is temporarily increased and the indoor fan of the stop indoor unit is operated at a low speed. Harmony machine.

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