JP2015152275A - Air conditioning device and control method of air conditioning device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air conditioning device and control method of the same capable of achieving a continuous and stable cooling operation at low load time and capable of reducing energy consumption during the cooling operation.SOLUTION: An air conditioning device includes: a compressor 11; an external heat exchanger 52 for cooling a compressed refrigerant; a decompression unit 14 for decompressing the cooled refrigerant; a first internal heat exchanger 12 for evaporating the decompressed refrigerant; a second internal heat exchanger 13 arranged in an air flow passage in which air inside an object space flows, and at least connected to high pressure piping 21 in which the refrigerant flowing from the compressor 11 to the external heat exchanger 52 flows; bypass piping 33 for connecting the compressor 11 side and the external heat exchanger 52 side with respect to the second internal heat exchanger 13 in the high pressure piping 21; switching units 31, 32 arranged in a region connected to the high pressure piping 21 and the bypass piping 33, and adjusting a ratio of a flow rate of the refrigerant flowing in the second internal heat exchanger 13 and the bypass piping 33; and a control unit 40 for controlling the switching units 31, 32.

Description

  The present invention relates to an air conditioner suitable for air conditioning in an information communication machine room and a method for controlling the air conditioner.

  Reheat control (also referred to as reheat control) is known as one of the controls for cooling and dehumidifying conditioned air. In reheat control, the return air, which is air taken in from the room, and the outside air, which is air taken from the outside for ventilation, all pass through a cooling coil (also referred to as an air cooler) of the air conditioner. During this passage, the return air and outside air (hereinafter referred to as “return air”, etc.) are deprived of heat and the temperature decreases, and the amount of water vapor contained due to dew condensation decreases (dehumidification also occurs). say.). The excessively cooled return air or the like is heated to a desired temperature by a reheater (also referred to as reheater), so-called reheat (reheat), and is sucked into the room.

  In the above-mentioned reheat control, as a reheater for reheating excessively cooled return air or the like, one using an electric heater and one using a refrigerant discharged from a compressor are known (for example, , See Patent Document 1).

  What uses the refrigerant | coolant discharged from the compressor is also called the refrigerant | coolant reheat system. In the refrigerant reheat system, two condensers are provided, and one of them is used as a reheater. The high-temperature refrigerant discharged from the compressor is guided to the reheater, and heat exchange is performed between the high-temperature refrigerant and the return air that is excessively cooled by the evaporator. In this way, the reheated return air or the like is sucked into the room.

JP 2006-200809 A

  Control of the blowing temperature, which is the temperature of the air taken into the room, is performed by capacity control by inverter control (frequency control) of a compressor that compresses the refrigerant. However, due to the structure of the compressor, it is known that capacity control by inverter control has a limit in the controllable range due to the relationship between the compressor frequency and the capacity. For example, the lower limit value of the controllable range can include a value of about 25% to 40% with respect to the rated capacity of the compressor.

  When the capacity of the compressor is controlled at a value lower than the above lower limit value, in other words, when the heat load on the air conditioner is small, a differential (operation gap) having a width including a desired set temperature T is ΔT. Based on this differential, the control for operating / stopping the compressor is performed. Hereinafter, the compressor stop is also referred to as thermo-OFF, and the compressor operation is also referred to as thermo-ON.

  When this control is performed, the following problem may occur. That is, even when the condition for turning on the thermo again after the thermo is turned off is satisfied and the operation of the compressor is resumed, there is a possibility that the upper limit temperature allowed in the room may be exceeded. This is considered to be due to a further increase (overshoot) in the room temperature due to the influence of detection delay of information used for determining the thermo-ON condition, heat capacity, and the like. Further, in order to protect the compressor, after the thermo-OFF is performed, control is often performed so that the thermo-ON condition is not satisfied and the operation of the compressor is not resumed for a period of several minutes.

  As a method for maintaining the room temperature or the temperature of the region to be controlled within the allowable upper limit temperature as described above, a method of setting the differential width ΔT as small as possible is conceivable. However, if ΔT is set small, the operation stop of the compressor is frequently repeated, which may shorten the life of the compressor.

  Furthermore, in the inverter control of the compressor, since it is necessary to perform the control before starting the compressor, and a time delay occurs also in the control for increasing the operating frequency of the compressor, ΔT is set small. Even so, there is a problem that it is difficult to maintain the room temperature within the upper limit temperature that is always allowed.

  For this reason, if a space with a small heat generation load, such as a container-type data center, is a space that is subject to temperature control, if you try to keep it within the allowable upper limit temperature, the air conditioner thermo-on or off, in other words, compressor operation The stop is repeated. As a result, an event in which the temperature of the target space greatly increases or decreases is frequently observed.

  The following techniques are known as techniques for suppressing such an event. In other words, when it is necessary to perform air-conditioning operation with a heat load that is lower than the lower limit of the partial load in an air conditioner that does not have a refrigerant reheat function, the compressor operation is stopped by using an air conditioner that has a refrigerant reheat function. There is known a technique for preventing the temperature of the blown air from being excessively lowered while continuing the air-conditioning operation without causing the air-conditioning operation to occur.

  The technique described in Patent Document 1 is a technique whose main purpose is dehumidification. However, as in the above-described technique, when the air-conditioning operation is performed in a state of a thermal load below the lower limit value of the partial load, the technique is continuously applied. It is also effective as a technology for realizing stable operation.

  On the other hand, the air conditioning operation using the refrigerant reheat function (hereinafter referred to as “reheat operation”) is an operation in which the temperature of the air is set to a desired temperature by reheating the air once cooled. In other words, it is an operation in which heating and cooling are performed simultaneously in the same indoor unit. Therefore, more energy is consumed during the air-conditioning operation than in a normal cooling operation or an operation to which the thermo on / off control is applied.

  An air conditioner having a refrigerant reheat function constantly performs reheat operation under extremely low load heat generation conditions that are well below the partial load lower limit in normal operation. As a result, there is a problem that the energy consumed during the air-conditioning operation increases, which is contrary to the realization of energy saving that is often required in recent years.

  The present invention has been made to solve the above-described problem, and is an air conditioner capable of realizing continuous and stable cooling operation at low load and reducing energy consumption during cooling operation. And it aims at providing the control method of an air conditioning apparatus.

In order to achieve the above object, the present invention provides the following means.
The air conditioner of the present invention is an air conditioner that controls the air in a target space to a desired temperature, and is compressed by exchanging heat with a compressor that compresses a refrigerant and air outside the target space. An external heat exchanger that cools the refrigerant, a decompression unit that decompresses the refrigerant cooled by the external heat exchanger, and a first internal that exchanges heat with the air inside the target space and evaporates the decompressed refrigerant A heat exchanger and a second internal heat exchanger that is arranged on a flow path through which air inside the target space flows, and that is connected to at least a high-pressure pipe through which the refrigerant flowing from the compressor to the external heat exchanger flows. A bypass pipe connecting the compressor side and the external heat exchanger side to the second internal heat exchanger in the high-pressure pipe, and a region where the high-pressure pipe and the bypass pipe are connected to each other. Internal heat exchanger A switching unit for regulating the flow rate of the refrigerant flowing through preliminary the bypass pipe, and a control section for controlling the switching unit, characterized in that is provided.

  According to the air conditioner of the present invention, the air is cooled by the first internal heat exchanger, and the proportion of the high-temperature refrigerant discharged from the compressor is led to the second internal heat exchanger to increase the above-mentioned air by heat exchange. By heating, continuous and stable cooling operation at low load can be performed. That is, even when the air is cooled too much by simply cooling the air with the first internal heat exchanger, the air adjusted to an appropriate temperature by heating the air in the second internal heat exchanger is used as the target space. Can be supplied continuously and stably.

  Further, when the necessity for heating the air by the second internal heat exchanger is reduced, the ratio of the refrigerant flow rate led to the second internal heat exchanger is reduced and the ratio of the refrigerant flow rate led to the bypass pipe is increased. Thus, energy consumption during cooling operation is reduced. That is, comparing the case where the refrigerant flows through the second internal heat exchanger and the case where the refrigerant flows through the bypass pipe, the resistance value of the refrigerant flow is smaller when the refrigerant flows through the bypass pipe. Therefore, by appropriately adjusting the ratio of the flow rate of the refrigerant flowing through the second internal heat exchanger and the bypass pipe, it is possible to reduce the driving power of the compressor that circulates the refrigerant, and the amount of energy used for driving the compressor Can be reduced.

  In the present invention, in addition to the general meaning of heating when air that has been once cooled is heated to obtain conditioned air of a desired temperature, the air is heated to a temperature higher than the desired temperature. After that, the meaning of heating when obtaining conditioned air at a desired temperature by cooling, the process of heating the air and the process of cooling the air are performed in parallel, and the heated air and the cooled air are mixed and desired It also includes the meaning of heating when obtaining conditioned air at a temperature of. The same applies to “reheat”.

  The reheating method and reheat control generally perform dehumidification of conditioned air by heating after air subcooling or dehumidification by supercooling. In the present invention, as described above, air heating is performed. An explanation will be given, including a method for cooling air after performing the above, and a method for obtaining conditioned air while suppressing generation of moisture due to dehumidification by a method of mixing heated air and cooled air.

  In the above invention, the compressor is a variable capacity compressor in which a capacity of the refrigerant discharged in a predetermined period is controlled, and an operation state which is control information of the compressor is stored in the control unit. A storage unit is provided, and the control unit controls the switching unit based on at least one of an operation state of the compressor and a transition record that is an operation state of the compressor acquired from the storage unit. It is preferable.

  Thus, by controlling the switching unit based on at least one of the operating state of the compressor and the transition record, the ratio of the refrigerant flow rate led to the bypass pipe can be appropriately controlled and adjusted to an appropriate temperature. It becomes easy to supply air to the target space continuously and stably.

  In the above invention, the switching unit is a first switching unit disposed on the compressor side and a second switching unit disposed on the external heat exchanger side in a region where the high pressure pipe and the bypass pipe are connected. A refrigerant pipe connecting the first internal heat exchanger and the compressor; a first switching pipe connecting the first switching part; a refrigerant pipe connecting the decompression part and the first internal heat exchanger; A second switching pipe connecting to the second switching unit, and the first switching unit and the second switching unit further include a flow rate of the refrigerant flowing through the first internal heat exchanger, and The ratio of the flow rate of the refrigerant flowing through the first switching pipe, the second switching pipe, and the second internal heat exchanger is adjusted, and the control unit is the target in the second internal heat exchanger. Said compressed into space air In the case of releasing the heat of the medium, the flow rate of the refrigerant flowing through the second internal heat exchanger and the ratio of the flow rate of the refrigerant flowing through the bypass pipe to the first switching unit and the second switching unit. When the second internal heat exchanger causes the decompressed refrigerant to absorb the heat of the air in the target space, the refrigerant flows through the first internal heat exchanger. It is preferable to output a control signal for adjusting the flow rate and the ratio of the flow rate of the refrigerant flowing through the first switching pipe, the second switching pipe, and the second internal heat exchanger.

  In this way, a circuit that guides the decompressed refrigerant to the second internal heat exchanger and guides the refrigerant discharged from the compressor to the bypass pipe is realized. For example, the second internal heat exchanger can function as a condenser or a reheater, and can also function as an evaporator. In other words, the function as a condenser or reheater and the function as an evaporator can be switched.

  Also in the second internal heat exchanger, the refrigerant can be evaporated to cool the air, so that the energy consumption during the cooling operation can be reduced. That is, since the second internal heat exchanger is disposed on the flow path of the air to be heat-exchanged with the first internal heat exchanger, when the heat exchange with the air is not performed, the second internal heat exchanger is the air Become resistance to flow. When the refrigerant decompressed during the cooling operation is guided to the second internal heat exchanger, air can be cooled in the second internal heat exchanger in the same manner as the first internal heat exchanger. Therefore, compared with the case where air cannot be cooled in the second internal heat exchanger, it is possible to suppress unnecessary consumption of energy for blowing air.

  In the above invention, the switching unit is a three-way valve disposed on the compressor side in a region where the high-pressure pipe and the bypass pipe are connected, and the bypass pipe is connected from the second internal heat exchanger in the high-pressure pipe. A check valve for suppressing the flow of the refrigerant into the second internal heat exchanger is further provided on the external heat exchanger side in the region up to the position, and the control unit is provided in the second internal heat exchanger. When the heat of the compressed refrigerant is released to the air in the target space, the flow rate of the refrigerant flowing through the second internal heat exchanger and the refrigerant flowing through the bypass pipe are caused to flow into the three-way valve. It is preferable to output a control signal for adjusting the flow rate ratio.

  By using the three-way valve and the check valve in this way, the air is cooled by the first internal heat exchanger and the high temperature discharged from the compressor with a low-cost configuration as compared with the case of using two four-way valves. The above-mentioned air can be heated by increasing the ratio of leading the refrigerant to the second internal heat exchanger.

  In the above invention, the first internal heat exchanger and the second internal heat exchanger are arranged in series on a flow path through which air in the target space flows, and the first internal heat exchanger and the second internal heat exchanger A suction temperature measurement unit that measures the temperature of the air before passing through the room, or an indoor temperature measurement unit that measures the temperature of the air in the target space, and the control unit is configured to measure the suction temperature measurement unit or the room It is preferable to output a control signal that adjusts at least a ratio of the flow rate of the refrigerant flowing through the second internal heat exchanger and the bypass pipe based on the measurement signal output from the temperature measurement unit.

  In the said invention, the blowing temperature measurement part which measures the temperature of the said air after passing through the said 1st internal heat exchanger and the said 2nd internal heat exchanger is arrange | positioned, The said control part is further the said blowing temperature measurement. It is preferable to output a control signal that adjusts at least the ratio of the flow rate of the refrigerant flowing through the second internal heat exchanger and the bypass pipe based on the measurement signal output from the unit.

  In the above invention, between the first internal heat exchanger and the second internal heat exchanger, after passing through the first internal heat exchanger and before passing through the second internal heat exchanger. An inter-heat exchanger temperature measuring unit that measures the temperature of the air or the temperature of the air after passing through the second internal heat exchanger and before passing through the first internal heat exchanger. The control unit is further configured to adjust at least a ratio of the flow rate of the refrigerant flowing through the second internal heat exchanger and the bypass pipe based on a measurement signal output from the inter-heat exchanger temperature measurement unit. It is preferable to output a control signal.

  Thus, by controlling the ratio of the refrigerant flow rate based on the measurement signal output from the suction temperature measurement unit or the indoor temperature measurement unit, it is possible to appropriately control the flow rate of the refrigerant guided to the second internal heat exchanger. it can. That is, since the temperature of the air before passing through the first internal heat exchanger and the second internal heat exchanger is measured by the suction temperature measuring unit or the indoor temperature measuring unit, it flows through the second internal heat exchanger and the bypass pipe. It becomes easy to determine the ratio of the flow rate of the refrigerant. Therefore, for example, when the temperature of the sucked air is low, the flow rate of the high-temperature refrigerant guided to the second internal heat exchanger is increased, and it becomes easy to heat the air to an appropriate temperature.

  Furthermore, the flow rate of the refrigerant guided to the second internal heat exchanger is further appropriately controlled by further controlling the ratio of the refrigerant flow rate using the measurement signal output from the blow-out temperature measurement unit or the inter-heat exchanger temperature measurement unit. Can be controlled.

  In the above invention, the first internal heat exchanger and the second internal heat exchanger are arranged in series on a flow path through which air in the target space flows, and the first internal heat exchanger and the second internal heat exchanger A blow-out temperature measurement unit that measures the temperature of the air after passing through the exchanger is disposed, and the control unit is configured to at least perform the second internal heat exchange based on a measurement signal output from the blow-out temperature measurement unit. It is preferable to output a control signal that adjusts the ratio of the flow rate of the refrigerant flowing through the bypass pipe and the bypass pipe.

  Thus, by controlling the ratio of the refrigerant flow rate based on the measurement signal output from the blowing temperature measuring unit, the flow rate of the refrigerant guided to the second internal heat exchanger can be more appropriately controlled. That is, since the temperature of the air after the temperature is adjusted by the first internal heat exchanger and the second internal heat exchanger is measured by the blowout temperature measuring unit, whether or not the temperature of the air supplied to the target space is appropriate Is easy to determine. Therefore, for example, when the temperature of the air supplied to the target space is low, the flow rate of the high-temperature refrigerant guided to the second internal heat exchanger can be increased and the cooled air can be heated to an appropriate temperature. .

  The control method for an air conditioner of the present invention is the air conditioner of the present invention that controls the air in a target space to a desired temperature, and reheat control that cools and heats the sucked air to adjust it to the desired temperature. And a control method of an air conditioner that selects thermo-on / off control for controlling operation and stop of the compressor provided according to the temperature of the sucked air, wherein the air in the target space is set to a desired temperature. In another air conditioner to be controlled, a detection step for detecting whether or not protection control providing a period from shutdown to restart is performed to protect the compressor, and some of the other When the protection control is not executed in the air conditioner, at least a thermo on / off step for executing the thermo on / off control and all the other air conditioners If the protection control is detected as being executed it has, at least, characterized by having a a record heat executing the Rehito control.

  In the above invention, when it is detected that the protection control is executed in all the other air conditioners, an estimated temperature that is an air temperature after a predetermined period in the target space is estimated, and the estimated temperature A comparison step for comparing a predetermined allowable temperature, and in the thermo-on / off step, even when the estimated temperature is lower than the predetermined allowable temperature, at least the thermo-on / off control is executed, and the reheat is performed. In the step, it is preferable that at least the reheat control is executed even when the estimated temperature is equal to or higher than the predetermined allowable temperature.

  According to the control method of the air conditioning apparatus of the present invention, the thermo-on / off control in which the consumption energy is reduced during the cooling operation by having the detection step and the comparison step, and the continuous and stable cooling operation at the time of low load. Therefore, it is possible to appropriately select the reheat control that can perform the cooling operation, and thus it is possible to achieve continuous and stable cooling operation at low load and to reduce energy consumption during cooling operation.

  In other words, in other air conditioners that control the air in the same target space to a desired temperature, if air conditioning operation can be expected, the air conditioner that is the control target gives priority to reducing energy consumption and thermo-on / off. Control is performed. Similarly, when it is determined that the estimated temperature obtained in the comparison step is lower than the predetermined allowable temperature, it is considered that there is little need to perform air conditioning operation on the target space. Thermo on / off control is performed.

  On the other hand, if the air conditioning operation in other air conditioners cannot be expected and the estimated temperature obtained in the comparison step is determined to be equal to or higher than the predetermined allowable temperature, the air conditioning operation for the target space is performed. Since it is thought that there is a high necessity to perform, reheat operation is performed.

  In the above invention, in the comparison step, the estimated temperature is a measured temperature that is a temperature of air measured in the target space, and a cooling load in all air conditioners that control the air in the target space to a desired temperature. It is preferable to be obtained based on the sum, an estimation coefficient based on the characteristic value of the air and the characteristic value of the target space, and the predetermined period. By obtaining the estimated temperature in this way, the temperature of the air in the target space after a predetermined period from the present time can be estimated.

  In the above invention, the cooling load is a current value supplied to the heat generating device arranged in the target space, instead of the sum of the cooling loads in all air conditioners that control the air in the target space to a desired temperature. A value obtained based on the measured value is preferable.

  As described above, by determining the cooling load based on the measured value of the current value supplied to the heat generating device, it is possible to directly determine the cooling load as compared with the case where the sum of the cooling loads in the air conditioner is used. . The sum of the cooling loads is the cooling load in the air conditioner that detects the temperature of the air in the target space heated by the heat generated from the heat generating equipment, and therefore the variation in the amount of heat generated in the heat generating equipment that is the heat source is reflected. A predetermined time is required. On the other hand, since the measured value of the current value is directly related to the amount of heat generated in the heat generating device, compared to the sum of the cooling loads, the period until the variation in the amount of generated heat is reflected, The cooling load can be obtained directly.

  In the above invention, the estimation coefficient is preferably corrected based on a temperature of air in the target space measured during a period in which the compressor is stopped in the thermo-on / off control. By correcting the estimation coefficient in this way, the estimated temperature can be obtained more accurately. In other words, the environment surrounding the target space is not constant under the influence of seasonal changes and the like, and inflow and outflow of air and heat occur between the target space and the surrounding environment. In other words, a disturbance always acts on the target space. By correcting the estimation coefficient based on the temperature of the air in the target space measured during the period when the compressor is stopped, it is possible to obtain an estimated temperature that takes into account the influence of the above-mentioned disturbance, and a more accurate estimated temperature. Can be requested.

  In the above invention, when the measured temperature exceeds the predetermined allowable temperature during the period in which the compressor is stopped in the thermo-on / off control, it is used when the measured temperature exceeds the predetermined allowable temperature. The estimated coefficient that has been stored is stored as a limit value, and if the new estimated coefficient obtained in the subsequent correction deviates from the limit value, the new estimated coefficient may not be used for the estimation of the estimated temperature. preferable.

  By setting the estimation coefficient limit value in this way, it is possible to make it difficult for the temperature of the target space to exceed a predetermined allowable temperature. That is, the estimated temperature used when the temperature of the target space exceeds a predetermined predetermined allowable temperature is set as the limit value, so that the estimated temperature estimated is lower than the temperature of the target space after a predetermined period. It is suppressed. By using this estimated temperature, it becomes difficult for the temperature of the target space to exceed a predetermined allowable temperature.

  In the above invention, a priority order for executing the reheat control is determined in advance with the other air conditioning apparatus, and the reheat control is executed when the priority order is highest, and the other air conditioning apparatus It is preferable that the thermo on / off control is executed when the priority of the apparatus is high.

  Predetermining the priorities in this manner allows reheat control to be performed in one air conditioner and thermo on / off control to be performed in the remaining air conditioners when the comparison steps are simultaneously performed in a plurality of air conditioners. Is called. For this reason, the energy consumed by the plurality of air conditioners performing reheat control is suppressed from being unnecessarily increased. Moreover, when all the air conditioning apparatuses perform thermo on / off control, it is possible to suppress the temperature of the target space from rapidly increasing.

  According to the air conditioner of the present invention, the flow rate of the refrigerant guided to the second internal heat exchanger and the flow rate of the refrigerant guided to the bypass pipe are provided by providing the second internal heat exchanger, the bypass pipe, and the switching unit. Therefore, it is possible to achieve a continuous and stable cooling operation at a low load and to reduce energy consumption during the cooling operation.

  According to the control method of the air conditioner of the present invention, the reheating control or the thermo on / off control is performed while ensuring the safety of keeping the air in the target space at a desired temperature by further including the detection step and the comparison step. Can be done appropriately.

It is a mimetic diagram explaining composition of an air harmony device concerning a 1st embodiment of the present invention. It is a block diagram explaining the structure of the control part of FIG. It is a schematic diagram explaining the cooling operation in high load control. It is a schematic diagram explaining the cooling operation in medium load control. It is a schematic diagram explaining the cooling operation in reheat control. It is a schematic diagram explaining the structure of the air conditioning apparatus which concerns on the modification of the 1st Embodiment of this invention. It is a block diagram explaining the structure of the control part of FIG. It is a schematic diagram explaining the cooling operation in medium load control. It is a schematic diagram explaining the cooling operation in reheat control. It is a schematic diagram explaining the structure of the air conditioning apparatus which concerns on the 2nd Embodiment of this invention. It is a block diagram explaining the structure of the control part of FIG. It is a flowchart explaining the control which selects reheat priority control and thermo on / off priority control. It is a flowchart explaining control when reheat priority control is selected. It is a graph which shows the relationship between the suction temperature and time in reheat priority control. It is a flowchart explaining control when thermo on-off priority control is selected. It is a graph which shows the relationship between the suction temperature and time in thermo on-off priority control.

[First Embodiment]
Hereinafter, an air conditioner 1 according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 5. In this embodiment, the air conditioner 1 of the present invention is applied to an example used for air conditioning of a server room (target space) in which an information communication device such as a server in a data center (hereinafter referred to as “ICT device”) is arranged. To explain.

  As shown in FIG. 1, the air conditioner 1 mainly includes an indoor unit 10 disposed in a server room and an outdoor unit 50 disposed outside the server room. The indoor unit 10 includes a compressor 11, a first internal heat exchanger 12, a second internal heat exchanger 13, an expansion valve (decompression unit) 14, an indoor fan 15, and a control unit 40. Is provided.

  The compressor 11 sucks and compresses at least the gaseous refrigerant flowing out from the first internal heat exchanger 12, and discharges it as a high-temperature and high-pressure refrigerant. In the present embodiment, description will be made by applying to an example in which the operation frequency of the compressor 11 is controlled by inverter control and capacity control can be performed. A high-pressure pipe 21 that leads the refrigerant to the external heat exchanger 52 is connected to the discharge side of the compressor 11, and a suction pipe 22 that leads the refrigerant from at least the first internal heat exchanger 12 to the compressor 11 on the suction side. It is connected.

  The first internal heat exchanger 12 performs heat exchange between the refrigerant decompressed by the expansion valve 14 and the air, and by this heat exchange, the refrigerant evaporates and the air is cooled. The first internal heat exchanger 12 is disposed on a flow path through which the air guided from the server room into the indoor unit 10 by the indoor fan 15 and the air guided from the outside of the server room to the indoor unit 10 flow.

  The second internal heat exchanger 13 is a heat exchanger whose both ends are connected to the high-pressure pipe 21. In the high-pressure pipe 21 that connects the second internal heat exchanger 13 and the compressor 11, a first switching unit 31 that controls the flow of the refrigerant is disposed, and the second internal heat exchanger 13 and the external heat exchanger 52 are connected to each other. A second switching unit 32 that controls the flow of the refrigerant is disposed in the high-pressure pipe 21 to be connected.

  A bypass pipe 33 is connected between the first switching unit 31 and the second switching unit. The bypass pipe 33 is a pipe through which the refrigerant discharged from the compressor 11 flows while bypassing the second internal heat exchanger 13. In addition, a first switching pipe 34 is connected between the first switching unit 31 and the suction pipe 22. The first switching pipe 34 guides the refrigerant that has flowed out of the second internal heat exchanger 13 to the suction pipe 22 via the first switching unit 31. Further, a second switching pipe 35 is connected between the second switching unit 32 and a pipe connecting the expansion valve 14 and the first internal heat exchanger 12. The second switching pipe 35 guides at least a part of the refrigerant decompressed by the expansion valve 14 to the second internal heat exchanger 13 via the second switching unit 32.

  In the present embodiment, the first switching unit 31 controls the ratio of the flow rate flowing into the second internal heat exchanger 13 and the flow rate flowing into the bypass pipe 33 among the refrigerant discharged from the compressor 11. The description will be made by applying to an example of a four-way valve that guides all of the refrigerant flowing out of the second internal heat exchanger 13 to the first switching pipe 34. Similarly, the second switching unit 32 controls the ratio of the flow rate flowing into the first internal heat exchanger 12 and the flow rate flowing into the second internal heat exchanger 13 among the refrigerant decompressed by the expansion valve 14. On the other hand, description will be made by applying to an example of a four-way valve that guides the refrigerant flowing out from the second internal heat exchanger 13 and the bypass pipe 33 to the external heat exchanger 52.

  The first switching unit 31 and the second switching unit 32 may be four-way valves as described above, or control the refrigerant flow as described above by combining a plurality of flow control valves or two-way valves. It may be a flow rate control device or the like, and is not particularly limited.

  The expansion valve 14 is disposed between the external heat exchanger 52 and the first internal heat exchanger 12, and depressurizes the high-pressure liquid refrigerant that has flowed out of the external heat exchanger 52. As a method for controlling the expansion valve 14, a known method can be used and is not particularly limited.

  The indoor fan 15 guides the air inside the server room into the indoor unit 10 and also guides the air outside the server room for ventilation into the indoor unit 10. The format of the indoor fan 15 can be a known format and is not particularly limited.

  The control unit 40 controls the state of the cooling operation in the air conditioner 1, and is a microcomputer having a CPU (Central Processing Unit), ROM, RAM, an input / output interface, and the like. As shown in FIG. 2, the control program stored in the ROM or the like causes the CPU to function as the calculation unit 48 and causes the ROM or the like to function as the calculation unit 49. In addition, the control part 40 may be arrange | positioned in the indoor unit 10 like this embodiment, may be arrange | positioned outside the indoor unit 10, and does not specifically limit an arrangement position.

  The control unit 40 includes a second internal heat exchange measured by a third temperature sensor (inter-heat exchanger temperature measurement unit) 46 disposed between the first internal heat exchanger 12 and the second internal heat exchanger 13. A measurement signal of the temperature of the air heated by the vessel 13 and a second temperature sensor (blowing temperature) arranged in the vicinity of the air outlet of the indoor unit 10 on the downstream side of the air flow from the first internal heat exchanger 12 The measurement signal of the temperature of the blown air measured by the measurement unit 42 is input. Further, the temperature of the intake air measured by the first temperature sensor (suction temperature measuring unit) 41 disposed in the vicinity of the air suction port of the indoor unit 10 on the upstream side of the air flow from the second internal heat exchanger 13. A measurement signal is also input.

  Further, the control unit 40 measures the air temperature in the server room measured by the indoor temperature sensor (indoor temperature measuring unit) 43 disposed in the vicinity of the air inlet of the indoor unit 10, and is measured by the refrigerant temperature sensor 44. A refrigerant temperature measurement signal after being decompressed by the expansion valve 14 and a refrigerant temperature measurement signal sucked into the compressor 11 measured by the refrigerant temperature sensor 45 are also input. In addition, an operation state signal that is information indicating the operation frequency of the compressor 11 is also input to the control unit 40. The input operation state signal may be used for controlling the compressor 11 or may be stored in the calculation unit 49 as a transition record.

  On the other hand, the control unit 40 controls a control signal for controlling the operating frequency of the compressor 11, a control signal for driving and controlling the indoor fan 15, a control signal for driving and controlling the outdoor fan 51, and an opening degree of the expansion valve 14. And a control signal for instructing control of the refrigerant flow by the first switching unit 31 and the second switching unit 32 are output.

  As shown in FIG. 1, the outdoor unit 50 is mainly provided with an outdoor fan 51 and an external heat exchanger 52. The outdoor fan 51 guides outside air, which is air outside the server room, to the inside of the outdoor unit 50. The external heat exchanger 52 is between the high-temperature and high-pressure gas refrigerant discharged from the compressor 11, the refrigerant after heat exchange by the second internal heat exchanger 13, and the outside air guided by the outdoor fan 51. Heat exchange is performed. In addition, as a format of the outdoor fan 51 and the external heat exchanger 52, a well-known format can be used and it does not specifically limit.

  Next, the cooling operation in the air conditioning apparatus 1 having the above configuration will be described. The air conditioner 1 performs high load control, medium load control, and reheat control that is low load control according to the degree of cooling load. First, the cooling operation in the high load control will be described with reference to FIG.

  The control unit 40 performs high load control when it is determined that the cooling load of the air conditioner 1 is high, for example, the air temperature in the server room measured by the room temperature sensor 43 is higher than a predetermined temperature. . In the high load control, the second internal heat exchanger 13 is used as an evaporator and is used for cooling the air blown out to the server room. At this time, the operating frequency of the compressor 11 may be any frequency between the lowest frequency and the highest frequency.

  The control unit 40 guides all of the refrigerant discharged from the compressor 11 to the bypass pipe 33 with respect to the first switching unit 31 and causes the refrigerant flowing out of the second internal heat exchanger 13 to flow through the first switching pipe 34. The control signal that leads to is output. On the other hand, with respect to the second switching unit 32, the refrigerant guided by the bypass pipe 33 is guided to the external heat exchanger 52, and a part of the refrigerant decompressed by the expansion valve 14 is passed through the second switching pipe 35. Through the second internal heat exchanger 13.

  Furthermore, the control unit 40 determines the air temperature in the server room based on the measurement signals output from the indoor temperature sensor 43, the first temperature sensor 41, the second temperature sensor 42, the refrigerant temperature sensor 44, and the refrigerant temperature sensor 45. A control signal for controlling the compressor 11, the expansion valve 14, the indoor fan 15, and the outdoor fan 51 is output so that the temperature becomes. In addition, since the control which the control part 40 performs here can use well-known control, the description is abbreviate | omitted.

Thus, the flow of the refrigerant when the high load control is performed is as follows.
The high-temperature and high-pressure gaseous refrigerant compressed and discharged by the compressor 11 flows around the second internal heat exchanger 13 via the first switching unit 31, the bypass pipe 33 and the second switching unit. Thereafter, the refrigerant flows into the external heat exchanger 52, releases heat to the outside air by heat exchange with the outside air, and is cooled and liquefied.

  The liquefied refrigerant flows out of the external heat exchanger 52 and the pressure is reduced at the expansion valve 14. The decompressed refrigerant flows into the first internal heat exchanger 12 and flows into the second internal heat exchanger 13 through the second switching pipe 35 and the second switching unit 32.

  In the second internal heat exchanger 13, heat is exchanged between the refrigerant flowing in and the air guided into the indoor unit 10, and the refrigerant takes heat from the air and vaporizes. The air cooled by the second internal heat exchanger 13 is further heat-exchanged with the refrigerant that has flowed in the first internal heat exchanger 12 disposed on the downstream side of the air flow. The air further cooled in the first internal heat exchanger 12 is blown out from the indoor unit 10 to the server room.

  The refrigerant that has taken away the heat of the air in the second internal heat exchanger 13 and merged with the refrigerant vaporized in the first internal heat exchanger 12 via the first switching unit 31 and the first switching pipe 34, and the compressor 11 is inhaled. The compressor 11 compresses the sucked refrigerant and discharges it as a high-temperature and high-pressure refrigerant, and the above-described cycle is repeated.

Next, the cooling operation in the medium load control will be described with reference to FIG.
For example, when the high load control described above is performed, the control unit 40 determines that the air temperature in the server room measured by the room temperature sensor 43 or the first temperature sensor 41 is lower than a predetermined temperature, and When it is determined that the operation frequency of the compressor 11 is the lowest frequency, or the state where the operation frequency is the lowest frequency continues for a certain period, that is, when it is determined that the cooling load of the air conditioner 1 is low. Execute load control. In other words, when the high load control is being performed, the medium load control is executed when it is determined that the cooling capacity of the air conditioner 1 with respect to the cooling load is excessive only by controlling the operation frequency of the compressor 11. In the medium load control, the second internal heat exchanger 13 is not used as a condenser or an evaporator.

  The control unit 40 guides all of the refrigerant discharged from the compressor 11 to the bypass pipe 33 with respect to the first switching unit 31, and the refrigerant flows to the second internal heat exchanger 13 and the first switching pipe 34. Outputs a control signal to shut off. On the other hand, with respect to the second switching unit 32, the refrigerant guided from the bypass pipe 33 is guided to the external heat exchanger 52, and the refrigerant flows to the second internal heat exchanger 13 and the second switching pipe 35. Outputs a control signal to shut off.

  Further, the control unit 40 is based on measurement signals output from the indoor temperature sensor 43, the first temperature sensor 41, the second temperature sensor 42, the refrigerant temperature sensor 44, and the refrigerant temperature sensor 45, as in the case of performing high load control. Thus, a control signal for controlling the compressor 11, the expansion valve 14, the indoor fan 15, and the outdoor fan 51 is output so that the air temperature in the server room becomes a desired temperature.

Thus, the flow of the refrigerant when the medium load control is performed is as follows.
After the refrigerant is compressed and discharged by the compressor 11, the flow of the refrigerant until the pressure of the refrigerant is reduced at the expansion valve 14 is the same as in the case of the high load control, and the description thereof is omitted. The refrigerant decompressed by the expansion valve 14 flows into the first internal heat exchanger 12.

  In the first internal heat exchanger 12, heat is exchanged between the refrigerant that has flowed in and the air that has been introduced into the indoor unit 10, and the refrigerant takes heat from the air and vaporizes. The air cooled by the first internal heat exchanger 12 is blown out from the indoor unit 10 to the server room. The refrigerant that has taken the heat of air and vaporized in the first internal heat exchanger 12 is sucked into the compressor 11. The compressor 11 compresses the sucked refrigerant and discharges it as a high-temperature and high-pressure refrigerant, and the above-described cycle is repeated.

Next, the cooling operation in the reheat control will be described with reference to FIG.
The control unit 40 determines that the air temperature in the server room measured by the room temperature sensor 43 or the first temperature sensor 41 is lower than a predetermined temperature, for example, when the above-described medium load control is performed, and Reheating is performed when it is determined that the operation frequency of the compressor 11 is the lowest frequency, or the state where the operation frequency is the lowest frequency continues for a certain period of time, that is, when the cooling load of the air conditioner 1 is determined to be low. Execute control.

  In other words, the control unit 40 performs reheat control when it is determined that the cooling capacity of the air-conditioning apparatus 1 with respect to the cooling load is excessive only by controlling the operation frequency of the compressor 11 when the medium load control is performed. Execute. For the above determination, a measurement signal of the temperature of the blown air measured by the second temperature sensor 42 can be used. In the reheat control, the second internal heat exchanger 13 is used as a condenser and is used for heating the air sucked from the server room.

  The control unit 40 guides all of the refrigerant discharged from the compressor 11 to the second internal heat exchanger 13 with respect to the first switching unit 31 and flows the refrigerant to the bypass pipe 33 and the first switching pipe 34. Outputs a control signal to shut off. On the other hand, the refrigerant flowing out from the second internal heat exchanger 13 is guided to the external heat exchanger 52 with respect to the second switching unit 32, and the refrigerant flow to the bypass pipe 33 and the second switching pipe 35 is blocked. Output a control signal.

  The control unit 40 performs reheat control based on the measurement signals output from the third temperature sensor 46 and the second temperature sensor 42 in addition to the measurement signal output from the indoor temperature sensor 43. The third temperature sensor 46 measures the air temperature after being cooled by the first internal heat exchanger 12. Therefore, the measurement signal of the third temperature sensor 46 can also be used for determining whether to perform reheat control. The second temperature sensor 42 measures the temperature of the air blown out to the server room. Therefore, the measurement signal of the second temperature sensor 42 can also be used for determining whether to perform reheat control.

  Furthermore, the control unit 40 may perform reheat control based on the measurement signals output from both the third temperature sensor 46 and the second temperature sensor 42 as described above, or the third temperature sensor 46 and the second temperature sensor 46. Reheat control may be performed based on the measurement signal output from either one of the temperature sensors 42.

Thus, the flow of the refrigerant when the reheat control is performed is as follows.
The high-temperature and high-pressure gaseous refrigerant compressed and discharged by the compressor 11 flows into the second internal heat exchanger 13 via the first switching unit 31. In the first internal heat exchanger 12, heat exchange between the air heated by the second internal heat exchanger 13 and the low-temperature and low-pressure refrigerant is performed, and the air is cooled to a temperature suitable for air conditioning in the server room. The cooled air is blown out from the indoor unit 10 to the server room.

  The refrigerant that has exchanged heat with the second internal heat exchanger 13 flows into the external heat exchanger 52 from the second internal heat exchanger 13 through the second switching unit 32, and heat is exchanged with the outside air through the heat exchange. To cool and liquefy. The liquefied refrigerant flows out of the external heat exchanger 52 and the pressure is reduced at the expansion valve 14.

  All of the decompressed refrigerant flows into the first internal heat exchanger 12. In the first internal heat exchanger 12, heat is exchanged between the refrigerant that has flowed in and the air that has been introduced into the indoor unit 10, and the refrigerant takes heat from the air and vaporizes. In other words, the air is excessively cooled by the refrigerant.

  The excessively heated air is cooled by the first internal heat exchanger 12 and blown out to the server room as described above. On the other hand, the refrigerant that has taken the heat of the air and vaporized in the first internal heat exchanger 12 is sucked into the compressor 11. The compressor 11 compresses the sucked refrigerant and discharges it as a high-temperature and high-pressure refrigerant, and the above-described cycle is repeated.

  When the control unit 40 performs switching between the above-described high load control and medium load control and switching between the medium load control and the reheat control, the control unit 40 performs the first switching unit 31 and the second switching unit 32. A control signal for gradually switching the refrigerant flow.

  In the above description, switching from high load control to medium load control and switching from medium load control to reheat control have been described. Conversely, switching from reheat control to medium load control, and from medium load control to high load control. Switching to control is also performed.

  Further, when switching from high load control to reheat control through medium load control and performing high load control from reheat control through medium load control, the control unit 40 shifts control based on the following five pieces of information: May be determined. Note that the priority of selection when using these pieces of information is in the order of the attached symbols. (1) Information on the operating frequency of the compressor 11. (2) Information about the operating frequency of the compressor 11 and the suction temperature measured by the first temperature sensor 41, or information about the operating frequency of the compressor 11 and the indoor temperature measured by the indoor temperature sensor 43. (3) Information on the operating frequency of the compressor 11 and the blowing temperature measured by the second temperature sensor 42.

  (4) Information on the operating frequency of the compressor 11 and the suction temperature measured by the first temperature sensor 41 and the blowing temperature measured by the second temperature sensor 42, or the operating frequency of the compressor 11 and the indoor temperature sensor 43 Information on the measured indoor temperature and the blowing temperature measured by the second temperature sensor 42. (5) The operating frequency of the compressor 11, the suction temperature measured by the first temperature sensor 41, the blowing temperature measured by the second temperature sensor 42, and the second internal heat exchanger 13 measured by the third temperature sensor Information on the temperature of the heated air, or the operating frequency of the compressor 11, the room temperature measured by the room temperature sensor 43, the outlet temperature measured by the second temperature sensor 42, and the second temperature measured by the third temperature sensor. Information on the temperature of the air heated by the internal heat exchanger 13.

  When the ratio of the refrigerant flow rate is controlled based on the measurement signal output from the first temperature sensor 41 or the indoor temperature sensor 43 as in (2) above, the flow rate of the refrigerant guided to the second internal heat exchanger 13 is changed. It can be controlled appropriately. That is, since the temperature of the air before passing through the first internal heat exchanger 12 and the second internal heat exchanger 13 is measured by the first temperature sensor 41 or the indoor temperature sensor 43, the second internal heat exchanger 13 and The ratio of the flow rate of the refrigerant flowing through the bypass pipe 33 can be easily determined. Therefore, for example, when the temperature of the sucked air is low, it is easy to increase the flow rate of the high-temperature refrigerant guided to the second internal heat exchanger 13 and heat the air to an appropriate temperature.

  As described in (4) and (5) above, in addition to the measurement signal output from the first temperature sensor 41 or the indoor temperature sensor 43, the measurement output from the first temperature sensor 41 or the third temperature sensor 46. If the ratio of the refrigerant flow rate is further controlled using the signal, the flow rate of the refrigerant guided to the second internal heat exchanger 13 can be more appropriately controlled.

  When the ratio of the refrigerant flow rate is controlled based on the measurement signal output from the second temperature sensor 42 instead of the measurement signal output from the first temperature sensor 41 or the indoor temperature sensor 43 as in (3) above. The flow rate of the refrigerant guided to the second internal heat exchanger 13 can be appropriately controlled. That is, since the temperature of the air after the temperature is adjusted by the first internal heat exchanger 12 and the second internal heat exchanger 13 is measured by the second temperature sensor 42, the temperature of the air supplied to the server room is appropriate. It becomes easy to determine whether or not. Therefore, for example, when the temperature of the air supplied to the server room is low, the flow rate of the high-temperature refrigerant guided to the second internal heat exchanger 13 can be increased to heat the overcooled air to an appropriate temperature. it can.

  According to the air conditioner 1 having the above-described configuration, the air is cooled by the first internal heat exchanger 12, and the rate at which the high-temperature refrigerant discharged from the compressor 11 is led to the second internal heat exchanger 13 is increased. By heating the above-mentioned air by replacement, continuous and stable cooling operation at low load can be performed. In other words, even when the air is cooled by the first internal heat exchanger 12 and the air is cooled too much, the air adjusted to an appropriate temperature by heating the air in the second internal heat exchanger 13 The server room can be supplied continuously and stably.

  Further, when the necessity of heating the air by the second internal heat exchanger 13 is reduced, the ratio of the refrigerant flow rate led to the second internal heat exchanger 13 is reduced, and the ratio of the refrigerant flow rate led to the bypass pipe 33 By increasing the power consumption energy during cooling operation can be reduced. That is, when the case where the refrigerant flows through the second internal heat exchanger 13 and the case where the refrigerant flows through the bypass pipe 33, the resistance value of the refrigerant flow is smaller when the refrigerant flows through the bypass pipe 33. Therefore, by appropriately adjusting the ratio of the flow rate of the refrigerant flowing through the second internal heat exchanger 13 and the bypass pipe 33, the driving power of the compressor 11 that circulates the refrigerant can be reduced and used for driving the compressor 11. Energy consumption can be reduced.

  Furthermore, it is possible to realize a circuit that guides the decompressed refrigerant to the second internal heat exchanger 13 and guides the refrigerant discharged from the compressor 11 to the bypass pipe 33. Therefore, the second internal heat exchanger 13 can function as a condenser or a reheater, and can also function as an evaporator. In other words, the function as a condenser or reheater and the function as an evaporator can be switched.

  In the second internal heat exchanger 13 as well, the refrigerant can be evaporated to cool the air, and energy consumption during the cooling operation can be reduced. That is, since the second internal heat exchanger 13 is disposed on the air flow path that exchanges heat with the first internal heat exchanger 12, the second internal heat exchanger 13 is used when heat exchange with air is not performed. 13 becomes the resistance of the air flow. When the refrigerant decompressed during the cooling operation is guided to the second internal heat exchanger 13, the air can be cooled in the second internal heat exchanger 13 in the same manner as the first internal heat exchanger 12. Therefore, compared with the case where air cannot be cooled in the 2nd internal heat exchanger 13, it is suppressed that the energy for blowing air is consumed unnecessarily.

  In the above-described embodiment, the first internal heat exchanger 12 and the second internal heat exchanger 13 are arranged in series on the flow path through which the air guided into the indoor unit 10 flows. However, the second internal heat exchanger 13 may be arranged in series on the downstream side, and the first internal heat exchanger 12 may be arranged in series on the upstream side.

  Furthermore, the 1st internal heat exchanger 12 and the 2nd internal heat exchanger 13 do not need to be arranged in series, for example, may be arranged in parallel. Specifically, the flow path of the guided air is branched in the indoor unit 10, and the first internal heat exchanger 12 and the second internal heat exchanger 13 may be arranged in each of the branch branches. . In this case, the air after passing through the first internal heat exchanger 12 and the second internal heat exchanger 13 merges and is mixed, and then blown out from the indoor unit 10 to the server room.

[Modification of First Embodiment]
Next, an air conditioner according to a modification of the first embodiment of the present invention will be described with reference to FIGS. The basic configuration of the air conditioner of the present modification is the same as that of the first embodiment, but the configuration around the second internal heat exchanger is different from that of the first embodiment. Therefore, in the present embodiment, the peripheral configuration of the second internal heat exchanger will be described with reference to FIGS. 6 to 9 and description of other components and the like will be omitted.

  As shown in FIG. 6, the air conditioner 1 </ b> A according to the present modification mainly includes an indoor unit 10 </ b> A disposed in the server room and an outdoor unit 50. A three-way valve (first switching unit) 31A that controls the flow of the refrigerant is disposed in the high-pressure pipe 21 that connects the second internal heat exchanger 13 and the compressor 11 in the indoor unit 10A, and the second internal heat exchanger 13 A check valve 32 </ b> A is disposed in the high-pressure pipe 21 that connects the external heat exchanger 52.

  One end of the bypass pipe 33 is connected to the three-way valve 31 </ b> A, and the other end is connected between the check valve 32 </ b> A and the external heat exchanger 52 in the high-pressure pipe 21. In the present modification, unlike the first embodiment, the first switching pipe 34 and the second switching pipe 35 are not provided.

  In the present embodiment, the three-way valve 31 </ b> A is a valve that controls the ratio of the flow rate flowing into the second internal heat exchanger 13 and the flow rate flowing into the bypass pipe 33 among the refrigerant discharged from the compressor 11. A known type of valve can be used as the three-way valve 31A. The check valve 32A allows the refrigerant flow from the second internal heat exchanger 13 to the external heat exchanger 52, and regulates the refrigerant flow from the reverse external heat exchanger 52 to the second internal heat exchanger 13. To do. A known type of valve can be used as the check valve 32A.

  The control unit 40A controls the cooling operation state in the air-conditioning apparatus 1 in the same manner as the control unit 40 of the first embodiment. As shown in FIG. 7, the control unit 40A includes a third temperature sensor 46, a second temperature sensor 42, an air temperature measurement signal measured by the indoor temperature sensor 43, a refrigerant temperature sensor 44, and a refrigerant. A measurement signal of the refrigerant temperature measured by the temperature sensor 45 is input.

  On the other hand, the control unit 40A controls the control signal for controlling the operating frequency of the compressor 11, the control signal for driving and controlling the indoor fan 15, the control signal for driving and controlling the outdoor fan 51, and the opening degree of the expansion valve 14. And a control signal for instructing control of the refrigerant flow by the three-way valve 31A are output.

  Next, the cooling operation in the air conditioner 1A having the above configuration will be described. Unlike the air conditioner 1 of the first embodiment, the air conditioner 1A performs medium load control and reheat control that is low load control according to the degree of cooling load. First, the cooling operation in the medium load control will be described with reference to FIG.

  The control unit 40A performs medium load control when it is determined that the cooling load of the air conditioner 1A is high, for example, the air temperature in the server room measured by the indoor temperature sensor 43 is higher than a predetermined temperature. . In the medium load control in this modification, the second internal heat exchanger 13 is not used as an evaporator or a condenser.

  The control unit 40A guides all of the refrigerant discharged from the compressor 11 to the bypass pipe 33 and outputs a control signal for blocking the flow flowing into the second internal heat exchanger 13 to the three-way valve 31A. . Further, as in the case of the first embodiment, the control unit 40 </ b> A is based on the measurement signals output from the indoor temperature sensor 43, the second temperature sensor 42, the refrigerant temperature sensor 44, and the refrigerant temperature sensor 45. A control signal for controlling the compressor 11, the expansion valve 14, the indoor fan 15, and the outdoor fan 51 is output so that the air temperature becomes a desired temperature. Since the flow of the refrigerant when the medium load control is performed in this manner is the same as the flow during the medium load control in the air-conditioning apparatus 1 of the first embodiment, the description thereof is omitted.

Next, the cooling operation in the reheat control will be described with reference to FIG.
For example, when the above-described medium load control is performed, the control unit 40A determines that the air temperature in the server room measured by the room temperature sensor 43 is lower than a predetermined temperature, and the operating frequency of the compressor 11 Is the lowest frequency, or the reheat control is executed when it is determined that the state of the lowest frequency continues for a certain period. In the reheat control, the second internal heat exchanger 13 is used as a condenser and is used for heating the air sucked from the server room.

  The control unit 40A outputs, to the three-way valve 31A, a control signal that guides all of the refrigerant discharged from the compressor 11 to the second internal heat exchanger 13 and blocks the refrigerant flow to the bypass pipe 33. . In addition to the measurement signal output from the indoor temperature sensor 43, the control unit 40A applies the measurement signal output from the third temperature sensor 46 and the second temperature sensor 42 in the same manner as in the first embodiment. Even based, reheat control is performed. Since the flow of the refrigerant when the reheat control is performed in this manner is the same as the flow during the reheat control in the air-conditioning apparatus 1 of the first embodiment, the description thereof is omitted.

  According to the air conditioner 1A having the above-described configuration, the three-way valve 31A and the check valve 32A are used to discharge from the compressor 11 with a low-cost configuration as compared with the first embodiment using two four-way valves. The ratio of the conducted high-temperature refrigerant to the second internal heat exchanger 13 is increased, the air is heated by heat exchange, and the above-described air is cooled by the first internal heat exchanger 12, thereby continuously In addition, stable cooling operation can be performed. Further, when the necessity of heating the air by the second internal heat exchanger 13 is reduced, the ratio of the refrigerant flow rate led to the second internal heat exchanger 13 is reduced, and the ratio of the refrigerant flow rate led to the bypass pipe 33 By increasing the power consumption energy during cooling operation can be reduced.

[Second Embodiment]
Next, an air conditioner according to a second embodiment of the present invention will be described with reference to FIGS. 10 to 16. The basic configuration of the air conditioner of this embodiment is the same as that of the first embodiment, but the control method of the air conditioner is different from that of the first embodiment. Therefore, in this embodiment, the control method of an air conditioning apparatus is demonstrated using FIGS. 10-16, and description of other components is abbreviate | omitted.

  As shown in FIG. 10, the air conditioning apparatus 101 according to the present embodiment mainly includes an indoor unit 110 disposed in the server room and an outdoor unit 50 disposed outside the server room. The indoor unit 110 is mainly provided with a compressor 11, a first internal heat exchanger 12, a second internal heat exchanger 13, an expansion valve 14, an indoor fan 15, and a control unit 140. Yes.

  The control unit 140 controls the state of the cooling operation in the air conditioning apparatus 101, and is a microcomputer having a CPU (Central Processing Unit), ROM, RAM, an input / output interface, and the like. As shown in FIG. 11, the control program stored in the ROM or the like causes the CPU to function as the calculation unit 48 and the command unit 143, and causes the ROM or the like to function as the calculation unit 49. Note that the control unit 140 may be disposed in the indoor unit 110 as in the present embodiment, or may be disposed outside the indoor unit 110, and the position of the control unit 140 is not particularly limited.

  The command unit 143 of the control unit 140 exchanges information with other control units mounted on other air conditioners arranged in the same server room. Examples of information to be exchanged include control information related to the compressor 11. In addition, as an information exchange method, information exchange may be performed directly with the other control units described above, or a center where information exchange is possible with a plurality of air conditioners arranged in the same server room. Information exchange may be performed via a control unit or the like.

Next, a control method in the air conditioner 1 having the above configuration will be described with reference to FIG.
When the cooling operation of the air conditioner 101 is started, the command unit 143 of the control unit 140 executes a process of acquiring control information of another compressor in the other air conditioner (S11: detection step). More specifically, processing for detecting whether or not protection control for providing a protection stop period from operation stop to restart is executed to protect other compressors. In addition, another air conditioning apparatus is another air conditioning apparatus that air-conditions the same server room, more specifically, the same cooling area.

  Thereafter, the control unit 140 executes a process of determining whether or not all other compressors are in the protection stop period (S12). When it is determined that the compressor is not under the protection stop control period in all other air conditioners (in the case of NO), the control unit 140 gives priority to the thermo on / off control in the air conditioner 101. (S13: Thermo-on / off step). Here, the fact that the compressor is not in the protective stop control in all the other air conditioners means that the compressor is not in the protective stop period in at least one other air conditioner. The thermo on / off priority control will be described later.

On the other hand, when it is determined that the compressor is in the period during which the protection stop control is performed in all the other air conditioners (in the case of YES), the control unit 140 performs the predetermined period t _recovery (hereinafter referred to as “ _recovery ”). The estimated temperature _Testimte (tr) (hereinafter also referred to as "Te (tr)") is obtained, and the estimated temperature Te (tr) is determined as a predetermined allowable temperature _Tlimit (hereinafter referred to as "Tl"). The process for determining whether or not the above is performed is executed (S14: comparison step).

  Specifically, the control unit 140 performs the above-described determination process based on the following formulas (1) and (2), in other words, a determination process based on temperature rise estimation. This process estimates the temperature rise during the period when the compressor is protected and stopped in all other air conditioners, and the temperature in the cooling area of the server room may exceed the predetermined allowable temperature Tl. Judgment is made.

ここで、Ｔ_estimte（ｔ）は経過時間ｔ後の推定温度（単位：Ｋ）であり、以後Ｔｅ（ｔ）とも表記する。Ｔ_{room-measured}は、測定されたサーバルームの冷却エリアの温度（単位：Ｋ）であり、以後Ｔｒｍとも表記する。Ｔｒｍは、例えば室内温度センサ４３により測定された温度を用いることができる。

Here, _Testimte (t) is an estimated temperature (unit: K) after the elapsed time t, and is hereinafter also expressed as Te (t). T _{room-measured} is the measured temperature (unit: K) of the cooling area of the server room, and is hereinafter also expressed as Trm. For example, the temperature measured by the indoor temperature sensor 43 can be used as the Trm.

Q is the cooling load (kW), which can be calculated by adding the air conditioning loads immediately before the calculation in the air conditioner that performs air conditioning in the cooling area of the same server room. c is the specific heat of air (J / kg · K), ρ is the density of air (kg / m ³ ), and V is the volume (m ³ ) of the cooling area of the server room. t is the elapsed time (s).

Further, t _recovery is a stop period in order to protect the compressor 11 in the air conditioner 101 that is the object of control, or a period (s) from compressor protection to recovery in the air conditioner other than the object of control. .

(CρV) _correction is an estimation coefficient based on an actual measurement value of a temperature rise transition during a period in which the compressor was stopped in the past, and a value corrected by learning is used. Hereinafter, it is also expressed as (cρV) c. . By using such a value as the estimation coefficient, it is possible to reduce the error of the estimated temperature Te (t) obtained by Expression (1).

However, when the thermo-on / off priority control is executed based on the estimated temperature Te (t) obtained by the equation (1), the temperature of the cooling area of the server room is predetermined during the protection stop period in which the compressor is stopped. When the allowable temperature T1 is exceeded, the control unit 140 stores the value of the estimation coefficient used at that time as an upper limit value (cρV) _{correction # NG} . Hereinafter, this upper limit value is also expressed as (cρV) c_NG.

  When the upper limit value (cρV) c_NG is set, the control unit 140 updates the value of the estimation coefficient when the value of the estimation coefficient becomes larger than the upper limit value (cρV) c_NG in the learning correction process. Do not do so, continue to use the previous value. In other words, the control unit 140 provides a restriction condition for learning correction of the estimation coefficient.

  By doing so, it is possible to suppress the estimation accuracy of the estimated temperature Te (t) from being deteriorated by the learning correction of (cρV) c, and the occurrence of an event in which the temperature of the cooling area of the server room exceeds the predetermined allowable temperature Tl. Can be suppressed.

  When it is determined that the estimated temperature Te (tr) is lower than the predetermined allowable temperature Tl (in the case of NO), the control unit 140 preferentially executes the thermo-on / off control (S13). On the other hand, when it is determined that the estimated temperature Te (tr) is equal to or higher than the predetermined allowable temperature Tl (in the case of YES), the control unit 140 preferentially executes the reheat control (S15: reheat). Step). Reheat priority control will be described later.

  Moreover, the priority order which performs reheat priority control between the air conditioning apparatus which air-conditions the same cooling area of a server room is memorize | stored in the calculating part 49 of the control part 140 previously. When detecting a temperature for determining whether to perform reheat control, which will be described later, or when detecting a temperature for determining whether to perform thermo-on / off control, at least one air conditioner according to the above-described priority order. The device performs reheat priority control.

Next, the control when the reheat priority control that performs the above-described reheat control with priority is selected will be described with reference to FIGS. 13 and 14.
If reheat priority control is selected in the control part 140, as shown in FIG. 13, the calculating part 48 of the control part 140 will determine whether the suction temperature has fallen below a predetermined temperature threshold value Tt. Execute (S21). The suction temperature can be exemplified by the air temperature measured by the first temperature sensor 41.

  When it is determined that the suction temperature is equal to or higher than the threshold value Tt (in the case of NO), the determination of S21 is repeated again. On the other hand, when it is determined that the suction temperature is lower than the threshold value Tt (in the case of YES), the calculation unit 48 performs a determination process as to whether or not the operating frequency of the compressor 11 is the lowest frequency. (S22).

  When it is determined that the operation frequency of the compressor 11 is not the lowest frequency (in the case of NO), the control unit 140 preferentially performs control for reducing the operation frequency of the compressor 11 (S23). On the other hand, when it is determined that the operating frequency of the compressor 11 is the lowest frequency (in the case of YES), the control unit 140 starts reheat control (S24).

  Specifically, a process for setting the reheat STEP is executed based on the opening degrees of the first switching unit 31 and the second switching unit 32, and the reheat control is started based on the set reheat STEP. At the beginning of the reheat control, STEP 1 having the lowest reheat capability is set as the reheat STEP. Note that the details of the reheat control are the same as those in the first embodiment, and a description thereof will be omitted.

  The calculation unit 48 of the control unit 140 has a predetermined period after the reheat control is started in S24, the control for increasing the reheat STEP in S27 described later is executed, or after the determination process of S28 is executed. It is determined whether or not it has passed (S25). That is, when it is determined that the predetermined period has not elapsed (in the case of NO), the determination process of S25 is repeated.

  When it is determined that the predetermined period has elapsed (in the case of YES), the calculation unit 48 executes processing for determining whether or not the suction temperature is equal to or lower than the threshold value Tt (S26). When it is determined that the suction temperature is equal to or lower than the threshold Tt (in the case of YES), the control unit 140 executes a process of increasing the reheat STEP set at that time by one (S27). When the value of reheat STEP increases, the flow rate of the refrigerant guided to the second internal heat exchanger 13 in the reheat control increases, and the amount of heat used for reheating in the second internal heat exchanger 13 increases.

  On the other hand, when it is determined in S26 that the suction temperature exceeds the threshold value Tt (in the case of NO), the calculation unit 48 performs a process of determining whether or not the suction temperature exceeds the threshold value Tt + X. Execute (S28). When it is determined that the suction temperature does not exceed the threshold value Tt + X (in the case of NO), the calculation unit 48 returns to S25 again and repeats the above-described processing. When it is determined that the suction temperature exceeds the threshold value Tt + X (in the case of YES), the control unit 140 ends the reheat priority control process, returns to the flowchart of FIG. 12, and repeats the control of FIG.

  FIG. 14 is a graph showing the relationship between the suction temperature and time when the above-described reheat priority control is performed. FIG. 14 shows an example in which the operation frequency of the compressor 11 is controlled to the lowest frequency of 10 Hz.

  Reheat priority control is performed, and reheat control is started at time A when the suction temperature falls below the threshold value Tt. The reheat STEP at time A is STEP1. Thereafter, in a period in which the suction temperature is below the threshold value Tt, the value of the reheat STEP is increased step by step every time a predetermined period elapses. Thereby, the reduction | decrease in suction temperature stops and it starts to raise.

  At time B when the suction temperature rises and exceeds the threshold value Tt, the process of increasing the reheat STEP is stopped. Thereafter, when the suction temperature further rises and reaches time point C exceeding the threshold value Tt + X, the reheat control is stopped. When the reheat control is stopped, the suction temperature starts decreasing after a slight time lag.

Next, the control when the thermo-on / off priority control that preferentially executes the above-described thermo-on / off control is selected will be described with reference to FIGS. 15 and 16.
When the thermo-on / off priority control is selected in the control unit 140, as shown in FIG. 15, the calculation unit 48 of the control unit 140 executes a determination process as to whether or not the operating frequency of the compressor 11 is the lowest frequency. (S31). When it is determined that the operating frequency of the compressor 11 is not the lowest frequency (in the case of NO), the process of S38 described later is executed.

  When it is determined that the operating frequency of the compressor 11 is the lowest frequency (in the case of YES), the calculation unit 48 performs a process of determining whether or not the suction temperature has fallen below a predetermined temperature threshold value Tt. Execute (S32). When it is determined that the suction temperature is equal to or higher than the threshold value Tt (in the case of NO), the process returns to the determination of S31 again and the above-described processing is repeated.

  When it is determined that the suction temperature is lower than the threshold value Tt (in the case of YES), the control unit 140 executes thermo-off control (S33). A known process can be used as the process actually performed as the thermo-off control, and the detailed description thereof is omitted here.

  When the thermo-off control is executed, the control unit 140 executes a process for determining whether or not a predetermined period has elapsed since the thermo-off control (S34). When it is determined that the predetermined period has not elapsed (in the case of NO), the determination of S34 is repeated again.

  When it is determined that the predetermined period has elapsed (in the case of YES), the calculation unit 48 performs a process of determining whether or not the suction temperature exceeds the threshold value Tt + X (S35). When it is determined that the suction temperature is equal to or lower than the threshold value Tt + X (in the case of NO), the calculation unit 48 returns to S34 again and repeats the above-described processing.

  When it is determined that the suction temperature exceeds the threshold value Tt + X (in the case of YES), the control unit 140 performs thermo-on control (S36). A known process can be used as the process actually performed as the thermo-on control, and the detailed description thereof is omitted here.

  When the thermo-on control is performed, the calculation unit 48 of the control unit 140 performs a determination process as to whether or not the operation frequency of the compressor 11 is the lowest frequency (S37). If it is determined that the operating frequency is the lowest frequency (in the case of YES), the process returns to S32 and the above-described processing is repeated.

  When it is determined that the operation frequency is not the lowest frequency in the process of S37 (in the case of NO), and when it is determined in the process of S31 described above that the operation frequency of the compressor 11 is not the lowest frequency (in the case of NO). The calculation unit 48 executes a process of determining whether or not the suction temperature is lower than the threshold value Tt (S38). When it is determined that the suction temperature is equal to or higher than the threshold value Tt (in the case of NO), the calculation unit 48 returns to the above-described S37 and repeatedly executes the above-described processing.

  When it is determined that the suction temperature is lower than the threshold value Tt (in the case of YES), the control unit 140 starts reheat control (S24). The calculation unit 48 of the control unit 140 determines whether or not a predetermined period has elapsed since the start of reheat control in S24 (S25). When it is determined that the predetermined period has not elapsed (in the case of NO), the process returns to S37 and the above-described process is repeatedly executed.

  When it is determined that the predetermined period has elapsed (in the case of YES), the calculation unit 48 executes processing for determining whether or not the suction temperature is equal to or lower than the threshold value Tt (S26). When it is determined that the suction temperature is equal to or lower than the threshold value Tt (in the case of YES), the control unit 140 executes a process of increasing the reheat STEP set at that time by one, and the compressor 11 A process of lowering the operating frequency by one step is executed (S39). Thereafter, the process returns to S37 and the above-described processing is repeatedly executed.

  On the other hand, when it is determined in S26 that the suction temperature exceeds the threshold value Tt (in the case of NO), the calculation unit 48 performs a process of determining whether or not the suction temperature exceeds the threshold value Tt + X. Execute (S28). When it is determined that the suction temperature does not exceed the threshold value Tt + X (in the case of NO), the calculation unit 48 returns to S37 again and repeats the above-described processing. When it is determined that the suction temperature exceeds the threshold value Tt + X (in the case of YES), the control unit 140 ends the reheat priority control process, returns to the flowchart of FIG. 12, and repeats the control of FIG.

  FIG. 16 is a graph showing the relationship between the suction temperature and time when the above-described thermo-on / off priority control is performed. In the thermo on / off priority control, unlike the case of the reheat priority control, the operation stop control of the compressor 11 is performed, and therefore, the change in the operation frequency is also included.

  The thermo-off control is started at the time point D when the suction temperature falls below the threshold value Tt during the period when the thermo-on / off priority control is performed and the operation frequency of the compressor 11 is the lowest frequency (for example, 10 Hz). By performing the thermo-off control, the operating frequency of the compressor 11 decreases from the lowest frequency to 0 Hz.

  If the suction temperature exceeds the threshold value Tt + X when the protection period Tp for protecting the compressor 11 has elapsed since the start of the thermo-off control, the thermo-on control is started. Here, an example is shown in which the compressor 11 is restarted at an operating frequency of 38 Hz. Reheat control is started at the time point F when the operating frequency of the compressor 11 is not the lowest frequency and the suction temperature falls below the threshold value Tt.

  Thereafter, in a period in which the operating frequency of the compressor 11 is not the lowest frequency and the suction temperature is lower than the threshold value Tt, the value of the reheat STEP is increased stepwise each time a predetermined period elapses. The operation frequency is reduced step by step. Thereby, the reduction | decrease in suction temperature stops and it starts to raise.

  When the suction temperature rises and the time point G exceeds the threshold value Tt, the process of increasing the reheat STEP is stopped. Thereafter, when the suction temperature further rises and becomes a time point H exceeding the threshold value Tt + X, the reheat control is stopped.

  According to the control method of the air conditioning apparatus 101 having the above-described configuration, by having the above-described steps S11 and S14, the thermo-on / off control for reducing the energy consumption during the cooling operation and the continuous operation at the time of low load are performed. In addition, since reheat control capable of performing stable cooling operation can be appropriately selected, it is possible to achieve continuous and stable cooling operation at low load and to reduce energy consumption during cooling operation.

  That is, in other air conditioners that control the air in the same cooling area of the server room to a desired temperature, if air conditioning operation can be expected, priority is given to reducing energy consumption in the air conditioner 101 to be controlled. Then, the thermo on / off control is performed. Similarly, when it is determined that the estimated temperature Te (t) obtained in step S14 is less than the predetermined allowable temperature Tl, it is considered that the necessity of performing the air conditioning operation on the cooling area of the server room is low. The thermo on / off control is performed with priority given to the reduction of energy consumption.

  On the other hand, when the air conditioning operation in other air conditioners cannot be expected, and when the estimated temperature Te (t) obtained in step S14 is determined to be equal to or higher than the predetermined allowable temperature Tl, Since it is considered highly necessary to perform air conditioning operation on the cooling area of the server room, reheat operation is performed.

  By determining the priority order in advance, when the step of S14 is simultaneously performed in a plurality of air conditioners, reheat control is performed in one air conditioner, and thermo on / off control is performed in the remaining air conditioners. Therefore, it can suppress that the energy consumed by several air conditioning apparatus performing reheat control unnecessarily increases. Moreover, it can suppress that the temperature of a server room rises rapidly because all the air conditioning apparatuses perform thermo on / off control.

By obtaining the estimated temperature Te (t) based on the above equation (1), the suction temperature in the cooling area of the server room after a predetermined period t _recovery from the present time can be estimated with relatively high accuracy.

By learning and correcting the estimation coefficient (cρV) _correction , the estimated temperature Te (t) can be obtained more accurately. In other words, the environment surrounding the server room cooling area is not affected by seasonal changes, and inflow or outflow of air or heat occurs between the server room cooling area and the surrounding environment. . In other words, disturbances always act on the cooling area of the server room. Obtaining the estimated temperature Te (t) taking into account the influence of the above-mentioned disturbance by correcting the estimation coefficient based on the temperature of the air in the server room cooling area measured during the period when the compressor 11 is stopped. And a more accurate estimated temperature Te (t) can be obtained.

  By setting the upper limit value of the estimation coefficient, it is possible to make it difficult for the temperature in the cooling area of the server room to exceed a predetermined allowable temperature Tl. That is, the estimated temperature Te (t) estimated by using the estimated coefficient used when the temperature of the cooling area of the server room exceeds a predetermined allowable temperature Tl as the upper limit is It is suppressed that it becomes lower than the temperature of the cooling area of the server room. By using this estimated temperature Te (t), it is possible to make it difficult for the temperature in the cooling area of the server room to exceed a predetermined allowable temperature Tl.

  In addition, you may use the total value of an air-conditioning load as Q used for Formula (1), and it calculates based on the measured value of the electric current supplied to heat generating apparatuses, such as an ICT apparatus arrange | positioned in the cooling area of a server room. It may be what you did.

  In this way, by determining the cooling load based on the measured value of the current value supplied to the ICT device, the cooling load is directly determined as compared to the case where the sum of the cooling loads in the air conditioning apparatus 101 is used. Can do. The sum of the cooling loads is the cooling load in the air conditioner 101 that detects the temperature of the air in the cooling area of the server room heated by the heat generated from the ICT device. Therefore, the amount of heat generated in the ICT device that is the heat source varies. A predetermined time is required for the reflection. On the other hand, since the measured value of the current value is directly related to the heat generation amount in the ICT device, the period until the fluctuation of the heat generation amount is reflected, compared to the sum of the cooling loads, The cooling load can be obtained directly.

  Further, in the present embodiment, it has been applied to an example in which it is determined whether or not the reheat STEP is increased every predetermined period by determining the elapse of the predetermined period in the process of S25. Instead, by determining whether or not the judgment formula based on the temperature transition is satisfied, the timing for determining whether or not to increase the reheat STEP may be defined, and is not particularly limited.

  In addition, like the above-mentioned embodiment, when it determines with it being during a protection stop period in all the other air conditioning apparatuses in the process of S12, priority is given to thermo on / off control based on estimated temperature Te (tr). Alternatively, the determination process (S14) for giving priority to the reheat control may be performed, or the determination process of S14 is not performed, and it is determined in the process of S12 that all other air conditioners are in the protection stop period. In such a case, control that prioritizes reheat control may be performed.

  The technical scope of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, the present invention is not limited to those applied to the above-described embodiments, and may be applied to embodiments obtained by appropriately combining these embodiments, and is not particularly limited.

  DESCRIPTION OF SYMBOLS 1,1A, 101 ... Air conditioning apparatus, 11 ... Compressor, 12 ... 1st internal heat exchanger, 13 ... 2nd internal heat exchanger, 14 ... Expansion valve (decompression part), 15 ... Indoor fan, 21 ... High pressure Pipe, 31 ... 1st switching part, 31A ... Three-way valve (1st switching part), 32 ... 2nd switching part, 33 ... Detour piping, 34 ... 1st switching pipe, 35 ... 2nd switching pipe, 40, 40A, DESCRIPTION OF SYMBOLS 140 ... Control part, 41 ... 1st temperature sensor (suction temperature measurement part), 42 ... 2nd temperature sensor (blowing temperature measurement part), 43 ... Indoor temperature sensor (indoor temperature measurement part), 46 ... 3rd temperature sensor ( (Inter-heat exchanger temperature measuring unit), 52 ... external heat exchanger, S11 ... detection step, S13 ... thermo on / off step, S14 ... comparison step, S15 ... reheat step

Claims (15)

An air conditioner that controls air in a target space to a desired temperature,
A compressor for compressing the refrigerant;
An external heat exchanger that exchanges heat with air outside the target space and cools the compressed refrigerant;
A decompression section for decompressing the refrigerant cooled by the external heat exchanger;
A first internal heat exchanger that exchanges heat with air inside the target space and evaporates the decompressed refrigerant;
A second internal heat exchanger that is disposed on a flow path through which air inside the target space flows, and is connected to at least a high-pressure pipe through which the refrigerant flowing from the compressor to the external heat exchanger flows;
A bypass pipe connecting the compressor side and the external heat exchanger side with respect to the second internal heat exchanger in the high-pressure pipe;
A switching unit that is disposed in a region where the high-pressure pipe and the bypass pipe are connected, and that adjusts a ratio of the flow rate of the refrigerant flowing through the second internal heat exchanger and the bypass pipe;
A control unit for controlling the switching unit;
An air conditioner characterized in that is provided. The compressor is a variable capacity compressor in which the capacity of the refrigerant discharged in a predetermined period is controlled,
The control unit is provided with a storage unit that stores an operation state that is control information of the compressor.
The control unit controls the switching unit based on at least one of an operation state of the compressor and a transition record which is an operation state of the compressor acquired from the storage unit. Item 1. An air conditioner according to Item 1. The switching unit is a first switching unit disposed on the compressor side in a region where the high-pressure piping and the bypass piping are connected, and a second switching unit disposed on the external heat exchanger side,
Refrigerant piping connecting the first internal heat exchanger and the compressor, and first switching piping connecting the first switching unit;
A refrigerant pipe connecting the decompression section and the first internal heat exchanger; a second switching pipe connecting the second switching section;
Is further provided,
The first switching unit and the second switching unit further include a flow rate of the refrigerant flowing through the first internal heat exchanger, and the first switching piping, the second switching piping, and the second internal heat exchanger. Adjusting the ratio of the flow rate of the refrigerant flowing through
When the control unit causes the air in the target space to release heat of the compressed refrigerant in the second internal heat exchanger, the control unit causes the first switching unit and the second switching unit to A control signal for adjusting a flow rate of the refrigerant flowing through the internal heat exchanger and a ratio of the flow rate of the refrigerant flowing through the bypass pipe;
In the second internal heat exchanger, when the decompressed refrigerant absorbs heat of the air in the target space, the flow rate of the refrigerant flowing through the first internal heat exchanger, and the first switching pipe The air conditioning apparatus according to claim 1 or 2, wherein a control signal for adjusting a ratio of a flow rate of the refrigerant flowing through the second switching pipe and the second internal heat exchanger is output. The switching unit is a three-way valve disposed on the compressor side in a region where the high-pressure pipe and the bypass pipe are connected,
A check valve for suppressing inflow of the refrigerant to the second internal heat exchanger is provided on the external heat exchanger side in a region from the second internal heat exchanger to the position where the bypass pipe is connected in the high-pressure pipe. Further provided,
In the second internal heat exchanger, when the controller releases the heat of the compressed refrigerant to the air in the target space, the refrigerant flows through the second internal heat exchanger to the three-way valve. The air conditioning apparatus according to claim 1 or 2, wherein a control signal for adjusting a flow rate of the refrigerant and a ratio of a flow rate of the refrigerant flowing through the bypass pipe is output. The first internal heat exchanger and the second internal heat exchanger are arranged in series on a flow path through which air in the target space flows,
A suction temperature measurement unit that measures the temperature of the air before passing through the first internal heat exchanger and the second internal heat exchanger, or an indoor temperature measurement unit that measures the temperature of the air in the target space is disposed. And
The control unit adjusts at least a ratio of the flow rate of the refrigerant flowing through the second internal heat exchanger and the bypass pipe based on a measurement signal output from the suction temperature measurement unit or the indoor temperature measurement unit. A control signal is output, The air harmony device according to any one of claims 1 to 4 characterized by things. A blowing temperature measuring unit that measures the temperature of the air after passing through the first internal heat exchanger and the second internal heat exchanger is disposed,
The control unit further outputs a control signal for adjusting at least a ratio of the flow rate of the refrigerant flowing through the second internal heat exchanger and the bypass pipe, based on the measurement signal output from the blowing temperature measuring unit. The air conditioning apparatus according to claim 5. Between the first internal heat exchanger and the second internal heat exchanger, the temperature of the air after passing through the first internal heat exchanger and before passing through the second internal heat exchanger Or an inter-heat exchanger temperature measurement unit that measures the temperature of the air after passing through the second internal heat exchanger and before passing through the first internal heat exchanger;
The control unit further adjusts at least a ratio of the flow rate of the refrigerant flowing through the second internal heat exchanger and the bypass pipe based on the measurement signal output from the inter-heat exchanger temperature measurement unit. Is output, The air conditioning apparatus of Claim 6 characterized by the above-mentioned. The first internal heat exchanger and the second internal heat exchanger are arranged in series on a flow path through which air in the target space flows,
A blowing temperature measuring unit that measures the temperature of the air after passing through the first internal heat exchanger and the second internal heat exchanger is disposed,
The control unit outputs a control signal for adjusting at least a ratio of a flow rate of the refrigerant flowing through the second internal heat exchanger and the bypass pipe, based on a measurement signal output from the blowing temperature measuring unit. The air conditioner according to any one of claims 1 to 4, wherein: The air conditioning apparatus according to any one of claims 1 to 8, wherein the air in the target space is controlled to a desired temperature, wherein reheat control is performed to cool and heat the inhaled air to adjust to a desired temperature, and A control method for an air conditioner that selects a thermo-on / off control that controls operation and stop of the compressor provided according to the temperature of intake air,
In another air conditioner that controls the air in the target space to a desired temperature, detection for detecting whether or not protection control is performed that provides a period from shutdown to restart to protect the compressor. Steps,
When the protection control is not executed in some of the other air conditioning apparatuses, at least a thermo on / off step for executing the thermo on / off control;
When it is detected that the protection control is being executed in all the other air conditioners, at least a reheat step for executing the reheat control;
A control method for an air conditioner characterized by comprising: When it is detected that the protection control is executed in all the other air conditioners, an estimated temperature that is an air temperature after a predetermined period in the target space is estimated, and the estimated temperature and the predetermined allowable temperature are calculated. A comparison step for comparing;
In the thermo-on / off step, even when the estimated temperature is lower than the predetermined allowable temperature, at least the thermo-on / off control is executed,
The method for controlling an air conditioner according to claim 9, wherein, in the reheat step, at least the reheat control is executed even when the estimated temperature is equal to or higher than the predetermined allowable temperature.   In the comparison step, the estimated temperature is a measured temperature that is a temperature of air measured in the target space, a sum of cooling loads in all air conditioners that control the air in the target space to a desired temperature, and the air The method of controlling an air conditioner according to claim 10, wherein the control method is obtained based on an estimation coefficient based on a characteristic value of the target space and a characteristic value of the target space, and the predetermined period.   The cooling load is a measured value of a current value supplied to the heat generating device arranged in the target space, instead of the sum of the cooling loads in all the air conditioners that control the air in the target space to a desired temperature. 12. The method of controlling an air conditioner according to claim 11, wherein the value is obtained based on the value.   The air according to claim 11 or 12, wherein the estimation coefficient is corrected based on a temperature of air in the target space measured during a period in which the compressor is stopped in the thermo-on / off control. Harmonic device control method. When the measured temperature exceeds the predetermined allowable temperature during the period when the compressor is stopped in the thermo-on / off control,
Storing the estimated coefficient used when the measured temperature exceeds the predetermined allowable temperature as a limit value;
14. The control of the air conditioner according to claim 13, wherein if the new estimated coefficient obtained in the subsequent correction deviates from the limit value, the new estimated coefficient is not used for the estimation of the estimated temperature. Method. Priorities for executing the reheat control are determined in advance with the other air conditioner,
When the priority is the highest, the reheat control is executed,
The method for controlling an air conditioner according to any one of claims 9 to 14, wherein the thermo-on / off control is executed when the priority of the other air conditioner is high.

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