JP2014070753A - Air conditioning equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide air conditioning equipment performing both of a compressor cycle operation and a pump cycle operation, the air conditioning equipment achieving further improved efficiency in the pump cycle operation.SOLUTION: The air conditioning equipment includes calculating means for calculating an opening of an expansion valve 4 and a rotational frequency of a pump 3 to keep outlet-side superheat of an evaporator 5 to a first set superheat, the calculating means calculates the rotational frequency of the pump 3 as a lower limit rotational frequency, when the outlet-side superheat of the evaporator 5 can be kept at the first set superheat by setting the opening of the expansion valve 4 to a prescribed opening, when the outlet-side superheat of the evaporator 5 is the first set superheat or more. The calculating means further calculates the rotational frequency of the pump 3 to be a prescribed rotational frequency more than the lower limit rotational frequency, when the outlet-side superheat of the evaporator is the first set superheat or more even though the opening of the expansion valve 4 is kept at an upper limit opening, when the outlet-side superheat of the evaporator 5 is the first set superheat or more, and then a compressor cycle operation is switched to a pump cycle operation.

Description

  The present invention relates to an air conditioner, and particularly to an apparatus that performs both a compressor cycle operation by a compressor and a pump cycle operation by a pump.

  In order to construct a computer network, a server for communication, a database, a file management, etc. is required to receive and process a request from each computer. This type of server is installed in the server machine room for convenience of operation and management. A plurality of servers are stored in a server rack, and a plurality of server racks are installed in the server machine room. The server generates a large amount of heat during operation, and an air conditioner is installed in the server machine room for stable operation.

  Here, as an air conditioner for the entire server machine room, in general, a compressor, an outdoor heat exchanger (condenser), an expansion valve, and an indoor heat exchanger (evaporator) are sequentially connected by a refrigerant pipe to constitute a refrigeration cycle. An air conditioner is used.

  However, since the server machine room is operated at about 30 ° C, if the outside air temperature is lower than that, for example in the case of midwinter, the refrigerant is directly cooled by the outside air by simply circulating the refrigerant without using the compressor. Therefore, cooling operation can be performed. However, the method of directly taking outside air is not suitable in an environment such as a server machine room because humidity adjustment and removal of impurities such as dust are necessary. In view of this, a technique called an indirect outdoor air cooling system in which cold air from outside air is transported through a heat exchanger of an air conditioner has attracted attention. By cooling the refrigerant with outside air in an outdoor heat exchanger (condenser) and forcibly circulating the refrigerant, cooling can be performed without using the compressor. It is known that for forced circulation of the refrigerant, a cooling operation can be performed with lower power consumption than the power consumption when the compressor is driven by using a refrigerant pump.

  In this regard, Patent Document 1 discloses a compressor cycle operation in which a compressor, an outdoor heat exchanger (condenser), an expansion valve, and an indoor heat exchanger (evaporator) are sequentially connected by a refrigerant pipe, and the outside of the room air temperature is exceeded. Under conditions such as winter and nighttime when the temperature is low, the refrigerant pump, the outdoor heat exchanger (condenser), the expansion valve, and the indoor heat exchanger (evaporator) are connected to the refrigerant pipe in sequence, It is described that efficient operation is performed in an environment that requires annual cooling by switching the cycle according to the operation conditions.

Japanese Patent No. 4352604

  Patent Document 1 discloses a compression cycle in which the compressor, the outdoor heat exchanger (condenser), the expansion valve, and the indoor heat exchanger (evaporator) are sequentially connected by a refrigerant pipe, and the outdoor heat exchanger ( The air conditioner having two types of cycle configurations of a refrigerant pump cycle in which a condenser), the refrigerant pump, the expansion valve, and the indoor heat exchanger (evaporator) are sequentially connected by refrigerant piping is used to open and close the expansion valve. It is described that the amount of refrigerant circulation is adjusted by controlling the degree and the rotational speed of the refrigerant pump.

  According to the pump cycle operation by the pump, significant power saving can be achieved as compared with the compressor cycle operation by the compressor. However, the power consumption by the pump in the pump cycle operation is not negligible, and further power saving is required. In the air conditioning apparatus described in the above-mentioned patent document, further improvement in this respect is necessary.

  Therefore, an object of the present invention is to provide an air conditioner that can further improve the efficiency of the pump cycle operation in the air conditioner that performs both the compressor cycle operation and the pump cycle operation.

  In order to achieve the above-described object, the present invention provides a compressor that performs a compressor cycle operation for circulating a refrigerant, a condenser that condenses the refrigerant compressed by the compressor, and a refrigerant condensed by the condenser. An expansion valve that expands; an evaporator that evaporates the refrigerant expanded by the expansion valve; and a pump cycle that circulates the refrigerant by sending liquid refrigerant flowing from the condenser to the expansion valve while the compressor is stopped. An expansion valve for setting the outlet-side superheat degree of the evaporator to a first set superheat degree before switching from the compressor cycle operation to the pump cycle operation. And calculating means for calculating the opening degree of the expansion valve when the outlet side superheat degree of the evaporator is greater than or equal to the first set superheat degree. When the outlet side superheat degree of the evaporator can be set to the first set superheat degree by setting the constant opening degree, the rotation speed of the pump is calculated as a lower limit rotation speed, and the outlet side of the evaporator When the degree of superheat is equal to or higher than the first set superheat degree, even if the opening degree of the expansion valve is set as the upper limit opening degree, when the outlet side superheat degree of the evaporator is equal to or higher than the first set superheat degree, the rotation of the pump The number is calculated to be a predetermined number of rotations greater than the lower limit number of rotations, and after calculating the opening degree of the expansion valve and the number of rotations of the pump by the calculation means, the compressor cycle operation is changed to the pump cycle operation. It is characterized by “switching”.

  Problems, configurations, and effects other than those described above will be clarified by the following description of embodiments.

  ADVANTAGE OF THE INVENTION According to this invention, in the air conditioning apparatus which performs both a compressor cycle driving | operation and a pump cycle driving | operation, the air conditioning apparatus which can aim at the further efficiency improvement of a pump cycle driving | operation can be provided.

The refrigeration cycle block diagram of Example 1 is shown. It is an example of the flowchart explaining the calculation method of the pump rotation speed and expansion valve opening degree of Example 1. FIG. The refrigeration cycle block diagram of Example 2 is shown. It is an example of the flowchart explaining the calculation method of the pump rotation speed and expansion valve opening degree of Example 2.

Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a diagram illustrating a configuration of a refrigeration cycle of the air-conditioning apparatus according to the first embodiment. The air conditioner according to the present embodiment includes an outdoor unit housing 6 and an indoor unit housing 7, and the liquid blocking valves 18 and the gas blocking valves 19 of each housing are connected by piping. Then, the compressor 1, the condenser 2, the expansion valve 4, and the evaporator 5 are sequentially connected by refrigerant piping to perform the cooling operation, the condenser 2, the forced refrigerant circulation pump 3, the expansion valve 4, and the evaporator 5 Are sequentially connected by refrigerant pipes, and both the pump cycle operation for cooling operation is performed. In both cycles, the condenser 2, the expansion valve 4, and the evaporator 5 are shared. A check valve 20 is connected to the outlet of the compressor 1 to prevent the liquid refrigerant from flowing backward. This check valve may be an open / close control according to the compressor operation.

  The forced refrigerant circulation pump 3 is installed alone in the outdoor unit housing 6 or in a separate unit, and an excess refrigerant adjusting device 9 is arranged between the condenser 2 and the inlet side of the forced refrigerant circulation pump 3 is A pressure sensor 10 and a temperature sensor 11 for monitoring the degree of supercooling of the refrigerant are arranged, and the frequency of the outdoor blower 8 is controlled according to the degree of supercooling.

  On the indoor unit 7 side, an indoor blower 17, an expansion valve 4, an evaporator 5 and a compressor 1 are mounted. The expansion valve 4, the evaporator 5, and the compressor 1 are sequentially connected by piping. The outlet side piping of the evaporator 5 is connected to the inlet side piping of the compressor 1, and in the case of compressor cycle operation, the refrigerant flows through this piping to form a cycle. A pipe for bypassing the compressor 1 is connected between the outlet side pipe of the evaporator 5 and the inlet side pipe of the compressor 1, and in the case of pump cycle operation, the refrigerant flows through this pipe so that the pump flows. Cycle operation is performed. A check valve 12 is connected to the pipe bypassing the compressor 1 to prevent the refrigerant discharged from the compressor 1 during the compressor cycle operation from flowing to the outlet side pipe of the evaporator 5. .

  The compressor cycle operation and the pump cycle operation are switched depending on the outside air temperature and the operation state. During the compressor cycle operation, when the outdoor temperature is sufficiently lower than the indoor temperature, if the cooling load continues to be less than the capacity that can be exhibited by the pump cycle operation, the operation is switched to the pump cycle operation. When the cooling load cannot be covered during the pump cycle operation or when the outdoor temperature continues to be high, the operation is switched to the compressor cycle operation.

  The refrigerant circulation amount during the pump cycle operation is adjusted by the frequency of the forced refrigerant circulation pump 3 or the opening degree of the expansion valve 4 so that the degree of superheat at the outlet of the evaporator 5 becomes a set value. The degree of superheat is calculated by calculating the saturation temperature of the refrigerant at that pressure from the pressure value obtained by the pressure sensor 14 disposed at the outlet of the evaporator 5 and calculating the difference from the temperature of the refrigerant obtained by the temperature sensor 13. To do. The inlet / outlet of the forced refrigerant circulation pump 3 is connected by a bypass pipe via a check valve 21 so as to bypass the forced refrigerant circulation pump 3 during the compressor cycle operation.

  Here, an upper limit value SH2 and a lower limit value SH1 are set for the outlet side superheat degree of the evaporator 5, and the refrigerant circulation amount is adjusted by comparing the set value with the calculated evaporator outlet side superheat degree SHe. I do.

  First, the case where the evaporator outlet side superheat degree SHe is lower than the lower limit value SH1 will be described. In this case, it is necessary to reduce the refrigerant circulation amount, but in this embodiment, the opening degree of the expansion valve 4 is reduced at this time. Instead, the frequency of the forced refrigerant circulation pump 3 is lowered stepwise. Thus, by reducing the rotational speed of the forced refrigerant circulation pump 3 before the expansion valve 4, while reducing the refrigerant circulation amount to the desired degree of superheat on the outlet side of the evaporator, the power consumption by the forced refrigerant circulation pump 3 is reduced. It is possible to reduce. Further, when the rotational speed of the forced refrigerant circulation pump 3 is decreased and the lower limit frequency is reached, if the evaporator outlet side superheating degree SHe is still lower than the lower limit value SH1, it is necessary to further reduce the refrigerant circulation amount. Therefore, the refrigerant circulation amount is reduced by gradually controlling the opening degree of the expansion valve 4 to be reduced. If the evaporator outlet side superheat degree SHe continues to be lower than the lower limit value SH1, the opening degree control is performed until the opening degree of the expansion valve 4 reaches the lower limit.

  Next, the case where the evaporator outlet side superheat degree SHe is higher than the upper limit value SH2 will be described. In this case, it is necessary to increase the amount of refrigerant circulation. In this embodiment, however, the frequency of the forced refrigerant circulation pump 3 is set at this time. Instead of increasing, first, the opening degree control for increasing the opening degree of the expansion valve 4 is performed. As a matter of course, the relationship is upper limit value SH2> lower limit value SH1. As a result, the amount of refrigerant circulating increases, so that it is not necessary to drive the pump 3 while maintaining the desired degree of superheat on the outlet side of the evaporator, and this can be done with low power consumption. If the evaporator outlet side superheat degree SHe continues to be higher than the upper limit value SH2 even when the opening degree of the expansion valve 4 reaches the upper limit, the frequency of the forced refrigerant circulation pump 3 is gradually increased from the lower limit frequency at this time. Increase the amount of refrigerant circulation. If the evaporator outlet side superheat degree SHe continues to be higher than the upper limit value SH2, control is performed until the frequency of the forced refrigerant circulation pump 3 reaches the upper limit.

  Here, when the rotational speed of the forced refrigerant circulation pump 3 and the opening degree of the expansion valve 4 are controlled after switching to the pump cycle by the above-described control, the temperature change of the load may occur transiently during that time. In addition, due to this, it becomes impossible to cover the cooling load, thereby switching to the compressor cycle operation, and the cycle operation may not be stable.

  Therefore, in this embodiment, before switching from the compressor cycle operation to the pump cycle operation, the rotation speed of the forced refrigerant circulation pump 3 and the expansion valve 4 so that the evaporator outlet side superheat degree SHe becomes a desired superheat degree. The opening is calculated. That is, the control unit of the air conditioner of the present embodiment sets the opening degree and the forcing of the expansion valve 4 to set the outlet side superheat degree of the evaporator 5 to the set superheat degree before switching from the compressor cycle operation to the pump cycle operation. Calculation means for calculating the number of revolutions of the refrigerant circulation pump 3 is provided. As a result, there is no lead time for shifting to the target capacity after switching the pump cycle operation, and the cycle can be stabilized.

  FIG. 2 shows a flowchart for calculating the opening degree of the expansion valve 4 and the rotational speed of the forced refrigerant circulation pump 3 before switching to the pump cycle operation by this calculating means. As described above, the upper limit value SH2 and the lower limit value SH1 are set for the outlet side superheat degree of the evaporator 5.

  First, the calculation means calculates whether or not the rotational speed of the forced refrigerant circulation pump 3 can be set to the lower limit rotational speed. That is, the rotational speed of the forced refrigerant circulation pump 3 is set to the lower limit rotational speed as much as possible to reduce the power consumption. When the degree of superheat on the outlet side of the evaporator 5 is equal to or higher than the first set value (upper limit SH2), the degree of superheat on the outlet side of the evaporator 5 can be lowered by increasing the rotational speed of the forced refrigerant circulation pump 3. However, an appropriate opening degree of the expansion valve 4 is calculated before that. That is, the outlet side superheat degree of the evaporator 5 is set to the first set value (upper limit SH2) by setting the lower limit opening of the expansion valve 4 while setting the rotation speed of the forced refrigerant circulation pump 3 to the lower limit rotation speed. It is possible to determine whether or not the outlet side superheat degree of the evaporator 5 can be set to the first set value (upper limit value SH2) by setting the opening degree to an appropriate opening degree or the upper limit opening degree. .

  In other words, the calculating means sets the opening degree of the expansion valve 4 to a predetermined opening degree when the outlet side superheat degree SHe of the evaporator 5 is equal to or higher than the first set superheat degree (upper limit SH2), so that the outlet side superheat degree of the evaporator 5 is set. When the degree can be set to the first set superheat degree (upper limit SH2), the rotational speed of the forced refrigerant circulation pump 3 is calculated as the lower limit rotational speed.

  Even if the opening degree of the expansion valve 4 is calculated as the upper limit opening degree, when the outlet side superheat degree SHe is equal to or higher than the first set superheat degree (upper limit value SH2), an appropriate rotation speed is set as the rotation speed of the forced refrigerant circulation pump 3. calculate. In other words, the calculation means sets the outlet side superheat degree of the evaporator 5 as the upper limit opening degree when the outlet side superheat degree of the evaporator 5 is equal to or higher than the first set superheat degree (upper limit SH2). When it is equal to or greater than 1 set superheat (upper limit SH2), the rotational speed of the forced refrigerant circulation pump 3 is calculated to be a predetermined rotational speed that is greater than the lower limit rotational speed. And after calculating the opening degree of the expansion valve 4 and the rotation speed of the forced refrigerant circulation pump 3 by the calculation means in this way, the compressor cycle operation is switched to the pump cycle operation. Thereby, it is possible to reduce power consumption by the forced refrigerant circulation pump 3 while maintaining a desired degree of heating at the outlet side of the evaporator. The lead time for shifting to the target capacity after switching the pump cycle operation is eliminated, and the cycle can be stabilized.

  Further, the evaporator outlet side superheat degree SHe, the upper limit value SH2 and the lower limit value SH1 are compared, the opening degree of the expansion valve 4 and the rotational speed of the forced refrigerant circulation pump 3 are controlled, and the desired evaporator outlet side superheat degree SHe Compared to the control to perform, by calculating the respective opening degree and rotation speed before switching as described above, transient temperature change can be suppressed, and the reliability of cycle operation can be ensured. Furthermore, the desired evaporator outlet side superheat degree She changes due to a transient temperature change until the desired evaporator outlet side superheat degree (upper limit SH2, lower limit value SH1) is reached, and the compressor cycle operation is resumed. It is possible to suppress the power consumption by maintaining the pump operation.

  Further, the calculation means calculates the rotational speed of the forced refrigerant circulation pump 3 when the outlet-side superheat degree of the evaporator 5 is equal to or lower than the second set superheat degree (lower limit value SH1) lower than the first set superheat degree (upper limit value SH2). When the outlet side superheat degree of the evaporator 5 can be set to the second set superheat degree (lower limit value SH1) by setting the rotation speed to a predetermined rotational speed, the opening degree of the expansion valve 4 is calculated as the upper limit opening degree. In other words, the calculating means calculates when the degree of superheat on the outlet side of the evaporator 5 needs to be increased, with the opening degree of the expansion valve 4 being set to the upper limit opening degree and firstly reducing the rotational speed of the forced refrigerant circulation pump 3. It is what you want to do.

  When the outlet-side superheat degree of the evaporator 5 is equal to or lower than the second set superheat degree (lower limit value SH1), the outlet-side superheat degree of the evaporator 5 is the second even if the rotational speed of the forced refrigerant circulation pump 3 is set to the lower limit rotational speed. When the degree of superheat (lower limit SH1) or less is set, the opening degree of the expansion valve 4 is calculated to be a predetermined opening degree that is smaller than the upper limit opening degree. In other words, the calculation means opens the expansion valve 4 when it is necessary to increase the outlet side superheat degree of the evaporator 5 and the rotational speed of the forced refrigerant circulation pump 3 is still the lower limit rotational speed. The degree is calculated as an appropriate opening degree. Then, after calculating the opening degree of the expansion valve 4 and the rotational speed of the forced refrigerant circulation pump 3 by the calculation means in this way, the same effect as described above can be obtained by switching from the compressor cycle operation to the pump cycle operation. It becomes possible.

  FIG. 3 is a diagram illustrating a configuration of the refrigeration cycle of the air-conditioning apparatus according to the second embodiment. The air conditioner according to the present embodiment is controlled by switching between the compressor cycle operation and the pump cycle operation. If the circulation amount of the refrigerant amount is excessive in the evaporator 5 during the pump cycle operation, the air conditioner is located near the compressor 1. Liquid refrigerant accumulates, and necessary and sufficient refrigerant does not flow to the forced refrigerant circulation pump 3, which may deteriorate the refrigeration cycle efficiency.

  For example, if the refrigerant flow rate control is performed by controlling the opening degree of only one expansion valve 4 as in the first embodiment, when the opening degree of the expansion valve 4 is narrowed, the evaporator 5 Since the amount of refrigerant entering the inlet path pipe is not necessarily uniform, there is a possibility that a flow rate distribution that is biased toward the refrigerant flowing in the evaporator 5 may be formed. If an uneven flow distribution is generated in the refrigerant passing through the evaporator 5, an appropriate heat exchange capacity may not be obtained, and reliability in the order of the superheat degree is lost. Further, if liquid refrigerant accumulates in the compressor 1, when switching to the compressor cycle operation, the liquid refrigerant flows to the compressor suction side, and liquid compression occurs, which may cause a failure of the compressor.

  Therefore, in FIG. 3, unlike FIG. 1, the evaporator 5 is constituted by a plurality of indoor heat exchangers (5-1, 5-2, 5-3) so that the refrigerant circulation amount can be adjusted more accurately. Is. Each indoor heat exchanger (5-1, 5-2, 5-3) is provided with an expansion valve (4-1, 4-2, 4-3) for controlling the refrigerant circulation amount. Furthermore, a temperature sensor 15 and a pressure sensor 16 for calculating the degree of refrigerant superheating on the outlet side are provided for each indoor heat exchanger for each indoor heat exchanger.

  Further, a temperature sensor 13 and a pressure sensor 14 are provided on the outlet side in the same manner as in FIG. 1 in order to calculate the outlet side superheat degree of the entire evaporator 5. A target outlet side superheat degree is set for each indoor heat exchanger (5-1, 5-2, 5-3), and this target outlet side superheat degree is a target outlet side as a whole of the evaporator. It is determined to be the degree of superheat. The target outlet superheat degree is set in a certain range determined from the upper limit value and the lower limit value as in the first embodiment, and control is performed so that the outlet side superheat degree falls within the range.

Next, the refrigerant | coolant circulation amount control of each specific indoor heat exchanger (5-1, 5-2, 5-3) is demonstrated.
In the present embodiment, as in the first embodiment, when the rotational speed of the forced refrigerant circulation pump 3 is the lower limit, the expansion valves (4-1, 4-2, 4-3) are controlled, and the expansion valves (4-1, 4, 4) are controlled. -2, 4-3) When the opening degree is the upper limit, the rotational speed of the forced refrigerant circulation pump 3 is controlled to switch to the pump cycle operation.

  Here, as described above, the target outlet side superheat degree is set in each of the indoor heat exchangers (5-1, 5-2, 5-3), and the temperature sensor 15 and the pressure installed in each of the indoor heat exchangers (5-1, 5-2, 5-3). Since the outlet side superheat degree can be calculated from the sensor 16, control is performed to throttle the expansion valve (4-1) of the indoor heat exchanger (for example, 5-1) in which the outlet side superheat degree is lower than the set lower limit value. . Thus, the evaporator 5 is comprised by several indoor heat exchangers (5-1, 5-2, 5-3), and control is carried out by each expansion valve (4-1, 4-2, 4-3). Therefore, it is possible to suppress the uneven performance in the evaporator and adjust the refrigerant circulation amount with higher accuracy.

  As described above, in the refrigerant circulation amount control according to the present embodiment, the evaporator 5 is configured by a plurality of indoor heat exchangers (5-1, 5-2, 5-3), and each expansion valve ( By performing the opening control of (4-1, 4-2, 4-3), it is possible to suppress unevenness in performance and adjust the refrigerant circulation amount with higher accuracy. As a result, liquid refrigerant can be prevented from accumulating near the compressor 1 during pump cycle operation, and necessary and sufficient refrigerant can flow to the forced refrigerant circulation pump 3, thereby preventing deterioration in refrigeration cycle efficiency. it can. Further, the liquid refrigerant does not accumulate due to the liquid refrigerant accumulating in the compressor 1, and the reliability of the compressor can be improved.

  Here, FIG. 4 shows the entire outlet side superheat degree of the evaporator 5, that is, the forced before switching to the pump cycle in order to set the outlet side superheat degree SHe calculated by the temperature sensor 13 and the pressure sensor 14 to the target superheat degree. The calculation method of the rotational speed of the refrigerant | coolant circulation pump 3 and each expansion valve (4-1, 4-2, 4-3) opening degree is demonstrated. The effects obtained here are the same as those described in the first embodiment.

  That is, the calculation means provided in the control unit of the air conditioner of the present embodiment has a plurality of expansion valves (4-1, 4) when the outlet-side superheat degree of the evaporator 5 is equal to or higher than the first set superheat degree (upper limit SH2). 4-2, 4-3), the degree of opening of the indoor heat exchanger (5-1, 5-2, 5-3) whose outlet side superheat degree is equal to or higher than the set superheat degree of the heat exchanger Is set to the predetermined opening, the outlet side superheat degree of the evaporator 5 can be set to the first set superheat degree (upper limit SH2), and the rotational speed of the forced refrigerant circulation pump 3 is set as the lower limit rotational speed. calculate.

  Moreover, when the outlet side superheat degree of the evaporator 5 is more than 1st setting superheat degree (upper limit SH2), the opening degree of a some expansion valve (4-1, 4-2, 4-3) is made into upper limit opening degree. In the case where the superheat degree on the outlet side of the evaporator 5 is equal to or higher than the first set superheat degree (upper limit SH2), the rotational speed of the forced refrigerant circulation pump 3 is calculated to be a predetermined rotational speed larger than the lower limit rotational speed. .

  Further, the calculation means sets the outlet side superheat degree of the evaporator 5 by setting the rotational speed of the forced refrigerant circulation pump 3 to a predetermined rotational speed when the outlet side superheat degree of the evaporator 5 is equal to or less than the second set superheat degree. When it can be set to 2 setting superheat degree (lower limit SH1), the opening degree of a plurality of expansion valves (4-1, 4-2, 4-3) is calculated as the upper limit opening degree.

  Further, even when the rotational speed of the forced refrigerant circulation pump 3 is set to the lower limit rotational speed, when the outlet side superheat degree of the evaporator 5 is equal to or lower than the second set superheat degree (lower limit value SH1), a plurality of expansion valves (4-1, 4 -2, 4-3), the degree of opening of the indoor heat exchanger (5-1, 5-2, 5-3) whose outlet side superheat is equal to or less than the set superheat of the heat exchanger It calculates so that it may become a predetermined opening degree.

  Then, after calculating the opening degree of the expansion valve 4 and the rotational speed of the forced refrigerant circulation pump 3 by the calculation means in this way, the same effect as that of the first embodiment can be obtained by switching from the compressor cycle operation to the pump cycle operation. It becomes possible.

1: Compressor 2: Outdoor heat exchanger (condenser)
3: Forced refrigerant circulation pump 4, 4-1, 4-2, 4-3: Expansion valves 5, 5-1, 5-2, 5-3: Indoor heat exchanger (evaporator)
6: Outdoor unit casing 7: Indoor unit casing 8: Outdoor blower 9: Excess refrigerant device 10, 14, 16: Pressure sensor 11, 13, 15: Temperature sensor 12, 20, 21: Check valve 17: Indoor blower 18: Liquid blocking valve 19: Gas blocking valve

Claims (4)

A compressor that performs a compressor cycle operation for circulating the refrigerant;
A condenser for condensing the refrigerant compressed by the compressor;
An expansion valve for expanding the refrigerant condensed by the condenser;
An evaporator for evaporating the refrigerant expanded by the expansion valve;
In an air conditioner comprising: a pump that performs a pump cycle operation of circulating a refrigerant by sending liquid refrigerant flowing from the condenser to the expansion valve in a state where the compressor is stopped.
Calculation means for calculating the opening degree of the expansion valve and the rotation speed of the pump for setting the outlet-side superheat degree of the evaporator to the first set superheat degree before switching from the compressor cycle operation to the pump cycle operation. With
The calculating means sets the opening degree of the outlet side of the evaporator to the first opening degree by setting the opening degree of the expansion valve to a predetermined opening degree when the outlet side superheating degree of the evaporator is equal to or higher than the first set superheating degree. When the set superheat degree can be set, the rotation speed of the pump is calculated as the lower limit rotation speed,
When the outlet side superheat degree of the evaporator is equal to or higher than the first set superheat degree, and the opening degree of the expansion valve is set to the upper limit opening degree, the outlet side superheat degree of the evaporator is equal to or higher than the first set superheat degree. Is calculated so that the rotation speed of the pump is a predetermined rotation speed larger than the lower limit rotation speed,
The air conditioner switching from the compressor cycle operation to the pump cycle operation after calculating the opening degree of the expansion valve and the rotation speed of the pump by the calculating means. In the air conditioning apparatus according to claim 1,
The calculating means sets the rotation speed of the pump to a predetermined rotation speed when the outlet-side superheat degree of the evaporator is equal to or lower than a second set superheat degree that is lower than the first set superheat degree. When the side superheat degree can be the second set superheat degree, the opening degree of the expansion valve is calculated as the upper limit opening degree,
When the outlet-side superheat degree of the evaporator is equal to or lower than the second set superheat degree, and when the outlet-side superheat degree of the evaporator is equal to or lower than the second set superheat degree even if the rotation speed of the pump is set to the lower limit rotational speed. Is calculated so that the opening degree of the expansion valve becomes a predetermined opening degree smaller than the upper limit opening degree. In the air conditioning apparatus according to claim 1 or 2,
The evaporator is configured by arranging a plurality of heat exchangers in parallel,
Expansion valves are respectively installed on the inlet sides of the plurality of heat exchangers,
The calculating means includes
When the outlet side superheat degree of the evaporator is equal to or higher than the first set superheat degree, among the plurality of expansion valves, the outlet side superheat degree of the heat exchanger is equal to or higher than the set superheat degree of the heat exchanger. When the opening degree of the thing can be set to the predetermined opening degree, the superheat degree on the outlet side of the evaporator can be set to the first set superheat degree, and the rotational speed of the pump is calculated as the lower limit rotational speed,
When the outlet-side superheat degree of the evaporator is equal to or greater than the first set superheat degree, the outlet-side superheat degree of the evaporator is equal to or greater than the first set superheat degree even if the opening degree of the plurality of expansion valves is set to the upper limit opening degree. In this case, the air conditioner is calculated so that the rotation speed of the pump is a predetermined rotation speed larger than the lower limit rotation speed. In the air conditioning apparatus according to claim 2,
The evaporator is configured by arranging a plurality of heat exchangers in parallel,
Expansion valves are respectively installed on the inlet sides of the plurality of heat exchangers,
The calculating means includes
When the outlet-side superheat degree of the evaporator is equal to or lower than the second set superheat degree, the pump-side superheat degree is set to the predetermined rotation speed so that the evaporator outlet-side superheat degree is set to the second set superheat degree. If it is possible to calculate the opening of the plurality of expansion valves as the upper limit opening,
If the outlet side superheat degree of the evaporator is equal to or lower than the second set superheat degree even when the rotation speed of the pump is set to the lower limit speed, among the plurality of expansion valves, the outlet side superheat degree of the heat exchanger. Is calculated so that the opening degree of the heat exchanger not exceeding the set superheat degree of the heat exchanger is a predetermined opening degree.