JP2012017889A - Air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air conditioner suppressing an interference of control over latent heat capacity with control over sensible heat capacity and achieving correct control over temperature and humidity.SOLUTION: This air conditioner 1 includes: a refrigerant circuit 100 connected with a compressor 110, an outdoor heat exchanger 120, an outdoor expansion valve 130, a first indoor expansion valve 140, and a first indoor heat exchanging section 150a; a bypass pipe 200 bypassing the outdoor heat exchanger 120 and outdoor expansion valve 130 and provided with a second indoor heat exchanging section 150b and a second indoor expansion valve 210 in the middle thereof; and a controller 300. The controller 300 performs dehumidification control for controlling the rotational speed of the compressor based on a target evaporation temperature which is set based on a difference between the humidity in an air-conditioned room and the target humidity and which is the target value of the evaporation temperature of a refrigerant passing through the first indoor heat exchanging section 150a, and performs temperature control for controlling the opening of each of the outdoor expansion valve and second indoor expansion valve based on a difference between temperature in the air-conditioned room and the target temperature.

Description

  The present invention relates to an air conditioner capable of reheat dehumidification operation.

  In an air conditioner capable of reheat dehumidification operation, the indoor heat exchanger includes a first indoor heat exchange unit that functions as an evaporator and a second indoor heat exchange unit that functions as a reheater during the reheat dehumidification operation. It is configured. FIG. 15 shows an example of a conventional air conditioner 8 capable of reheat dehumidification operation. The air conditioner 8 includes a compressor 110, an outdoor heat exchanger 120, an outdoor expansion valve 130, a second indoor expansion valve 170, a second indoor heat exchange unit 150b of the indoor heat exchanger 150, a first indoor expansion valve 140, and The 1st indoor heat exchange part 150a of the indoor heat exchanger 150 is provided with the refrigerant circuit 101 through which a refrigerant circulates in the circuit connected by refrigerant | coolant piping.

  The flow path of the high-pressure refrigerant vapor discharged from the compressor 110 is switched by the four-way switching valve 160. That is, during cooling operation or reheat dehumidification operation, it is led to the outdoor heat exchanger 120 as shown by a solid line, and during heating operation, it is led to the first indoor heat exchanger 150a of the indoor heat exchanger 150 as shown by a broken line. It is burned.

  FIG. 16 is a Mollier diagram (pressure-enthalpy diagram) showing a refrigeration cycle during the reheat dehumidifying operation of the air conditioner 8 shown in FIG. During the reheat dehumidifying operation, the outdoor heat exchanger 120 and the second indoor heat exchange unit 150b function as a condenser, and the condensing capacity is the amount of heat Qc released by the outdoor heat exchanger 120 and the second indoor heat exchange unit 150b. It is the sum of the amount of heat Qr released at. That is, since the reheat capacity Qr is limited to a part of the entire condensation capacity, for example, when the cooling load is small and dehumidification is necessary, the reheat capacity may be insufficient depending on the operation conditions. become.

  FIG. 17 is a moist air diagram for explaining a state in which the reheat capability is insufficient during the reheat dehumidifying operation of the air conditioner 8 shown in FIG. 15. A control target at the set temperature Ts and the set relative humidity Hs is indicated by a point 0. The temperature and humidity of the intake air before air conditioning is performed are indicated by point 1. FIG. 17 shows a case where the difference between the temperature of the intake air and Ts, that is, there is almost no cooling load, and the humidity of the intake air is higher than Hs, that is, dehumidification is required.

  When the evaporation capacity of the first indoor heat exchange unit 150a is suppressed to Qe1 and the temperature of the intake air is cooled within the range of the capacity Qr1 of the second indoor heat exchange unit 150b, the intake air is on the right side of the saturated air line. Since it is cooled only to the point 2, that is, the temperature higher than the dew point temperature, the intake air cannot be dehumidified. The blown air is heated by the capacity Qr1 of the second indoor heat exchange unit 150b, and further rises in temperature due to the indoor temperature load Qa1, but the humidity of the blown air after air conditioning does not change at point 1.

  On the other hand, when the dehumidification is prioritized and the evaporation capacity of the first indoor heat exchange unit 150a is exhibited to Qe2 to cool the intake air to the point 2 ′ on the saturated air line, the capacity Qr2 of the second indoor heat exchange unit 150b. Since the reheating capability is insufficient only by heating alone, even if the temperature rise due to the indoor temperature load Qa2 is added, it cannot be heated to the point 0 which is the target point. In this case, since the room temperature continues to decrease below the set temperature Ts, it is necessary to finally stop the compressor 110 (thermo off) and stop the refrigeration cycle.

  Furthermore, when the local piping is long, as indicated by a broken line in FIG. 16, a pressure loss ΔP occurs before reaching the indoor first indoor expansion valve 140 from the outdoor heat exchanger 120. Therefore, the capacity of the reheater decreases from Qr to Qr ′ (the capacity decrease amount is indicated by ΔQ). Therefore, compared with the case where the pressure loss ΔP does not occur, the reheating capability is insufficient even with a larger cooling load.

  In order to solve such a problem of the conventional air conditioner, a bypass pipe 202 that allows the refrigerant circulating in the refrigerant circuit 101 to bypass the outdoor heat exchanger 120 and the outdoor expansion valve 130 is provided as an outdoor unit. An air conditioner 9 provided inside the machine 38 is known (see Patent Document 1). FIG. 18 is a diagram schematically showing the air conditioner 9 described in Patent Document 1. As shown in FIG. In the middle of the bypass pipe 202, a second outdoor expansion valve 220 is provided. By adjusting the opening degree of the second outdoor expansion valve 220, the refrigerant flowing into the outdoor heat exchanger 120 and the outdoor heat exchanger 120 are connected. The ratio of the refrigerant that bypasses and flows into the second indoor heat exchange unit 150b is adjusted.

  FIG. 19 is a Mollier diagram showing a refrigeration cycle when the air conditioner 9 shown in FIG. 18 is in a reheat dehumidifying operation. During the reheat dehumidifying operation, the outdoor heat exchanger 120 and the second indoor heat exchanger 150b function as a condenser, and the condensing capacity is the amount of heat Qc released by the outdoor heat exchanger 120 and the second indoor heat exchanger. It is the same as the air conditioner 8 shown in FIG. 16 in that it is the sum of the amount of heat Qr released at 150b. However, since the ratio between the refrigerant flowing into the outdoor heat exchanger 120 and the refrigerant bypassing the outdoor heat exchanger 120 and flowing into the bypass pipe 202 is adjustable, the ratio between Qc and Qr is changed at an arbitrary ratio. be able to. It is also possible to make all of the condensation capacity the reheat capacity Qr. In the refrigeration cycle, the condensing capacity is larger than the evaporating capacity, so that the reheating capacity Qr corresponding to the evaporating capacity Qe can be obtained.

  FIG. 20 is a diagram for explaining that both dehumidification and temperature control are possible because the reheat capability according to the evaporation capability is obtained during the reheat dehumidifying operation of the air conditioner 9 shown in FIG. It is a wet air diagram. A control target at the set temperature Ts and the set relative humidity Hs is indicated by a point 0. The temperature and humidity of the intake air before air conditioning is performed are indicated by point 1. The difference between the temperature of the intake air and Ts, that is, there is almost no cooling load, and the humidity of the intake air is higher than Hs, that is, the case where dehumidification is necessary is the same as in FIG.

  When the intake air is cooled to the point 2 on the saturated air line for dehumidification, the temperature can be raised to the point 3 where the amount corresponding to the indoor temperature load Qa is reduced by the capacity Qr1 of the second indoor heat exchange unit 150b. . And the temperature of blowing air rises to preset temperature Ts with room temperature load Qa. Thus, by adopting the configuration of the air conditioner 9, dehumidification is possible even when there is almost no cooling load (sensible heat load).

Japanese Patent Laid-Open No. 7-294059

  Temperature control is performed by increasing or decreasing the sensible heat capacity, and humidity control is performed by increasing or decreasing the latent heat capacity. The rotational speed of the compressor 110, the opening degree of the first indoor expansion valve 140 (evaporator motorized valve), the opening degree of the second outdoor expansion valve 220 (outdoor motor motorized valve), etc. It becomes a control factor related to humidity control.

  FIG. 21 is a diagram showing the relationship between the rotation speed of the compressor 110 and the opening of the first indoor expansion valve 140 (evaporator motor-operated valve), and the sensible heat capacity and latent heat capacity. As the rotational speed of the compressor 110 increases, the amount of refrigerant circulating in the refrigerant circuit 101 increases, the pressure inside the first indoor heat exchange unit 150a (evaporator) decreases and the evaporation temperature decreases, Both latent heat capacity increases. When the opening degree of the first indoor expansion valve 140 (evaporator motorized valve) increases, the amount of refrigerant circulating in the evaporator increases, so that the sensible heat capacity increases, but in the first indoor heat exchanger 150a (evaporator). Since the refrigerant pressure increases and the evaporation temperature rises, the latent heat capacity decreases.

  FIG. 22 is a diagram illustrating the relationship between the opening degree of the second outdoor expansion valve 220 (outdoor unit motor-operated valve), the sensible heat capacity, and the latent heat capacity. When the opening degree of the second outdoor expansion valve 220 (outdoor unit motor operated valve) is increased, the amount of refrigerant flowing into the outdoor heat exchanger 120 decreases, and the amount of refrigerant flowing into the second indoor heat exchanger 150b (reheater). Increases, the sensible heat capacity decreases and the latent heat capacity increases.

  An example of control when the difference between the suction humidity and the set humidity is large and dehumidification is required when the difference between the suction temperature and the set temperature is small and the sensible heat load is small as shown in FIG. First, the rotational speed of the compressor 110 is increased to increase the latent heat capability. As the rotational speed of the compressor 110 increases, the sensible heat capacity also increases. Therefore, the opening degree of the first indoor expansion valve 140 (evaporator motor-operated valve) is reduced in order to reduce the sensible heat capacity. Furthermore, the opening degree of the second outdoor expansion valve 220 (outdoor unit motor-operated valve) is increased, the refrigerant flow rate to the outdoor heat exchanger 120 is reduced, the condensation capacity Qc is reduced, and the second indoor heat exchange unit 150b is connected. The reheat capacity Qr is increased by increasing the refrigerant flow rate.

  As described based on FIG. 21 and FIG. 22, the change of each control factor affects both the variation in latent heat capability and the variation in sensible heat capability. In the conventional air conditioner as shown in Patent Document 1, the latent heat capacity and the sensible heat capacity are controlled in conjunction with each other by changing control factors such as the rotational speed of the compressor and the opening of the expansion valve. Yes. For this reason, the control of the latent heat capability and the sensible heat capability interfered, and the actual numerical values sometimes did not approach the control target values of temperature and humidity. The present invention has been made in view of such conventional problems, and suppresses interference between the control of latent heat capability and the control of sensible heat capability, and air conditioning in which temperature and humidity control is performed with high accuracy. The purpose is to provide a machine.

  An air conditioner according to claim 1 of the present invention includes an indoor heat exchanger that includes a first indoor heat exchange unit that functions as an evaporator during a reheat dehumidifying operation and a second indoor heat exchange unit that functions as a reheater. And a compressor, an outdoor heat exchanger, an outdoor expansion valve whose opening degree can be adjusted, a first indoor expansion valve whose opening degree can be adjusted, and a first indoor heat exchange part of the indoor heat exchanger are connected by a refrigerant pipe. The bypass circuit bypasses the refrigerant circuit in which the refrigerant circulates in the circuit, the outdoor heat exchanger of the refrigerant circuit, and the outdoor expansion valve, and the opening degree of the indoor heat exchanger is adjustable. A bypass pipe that is a refrigerant pipe provided with a second indoor expansion valve in the middle, a room temperature detector that detects the room temperature of the air-conditioned room in which air conditioning is performed, a humidity detector that detects the humidity of the air-conditioned room, and air conditioning The operator enters at least one of the target temperature and target humidity A setting input unit, an evaporating temperature detecting unit for detecting an evaporating temperature of the refrigerant passing through the first indoor heat exchanging unit, the compressor, the outdoor expansion valve, the first indoor expansion valve, and the second indoor unit A control unit that controls the expansion valve, wherein the control unit calculates a difference ΔX between the humidity in the air-conditioned room detected by the humidity detection unit and the target humidity, and sets the target of the evaporation temperature based on the ΔX. A target evaporation temperature that is a value is set, dehumidification control is performed to control the rotation speed of the compressor based on the target evaporation temperature, and a difference ΔTr between the temperature in the air-conditioned room detected by the room temperature detection unit and the target temperature is calculated. The temperature control for calculating and controlling the opening degree of the second indoor expansion valve based on the ΔTr is performed.

  According to the first aspect of the present invention, the increase or decrease of the latent heat capacity related to the dehumidification control is made by the control unit controlling the rotation speed of the compressor based on the target evaporation temperature, and the sensible heat capacity related to the temperature control. The increase / decrease is performed by the control unit controlling the opening of the second indoor expansion valve based on the ΔTr. That is, it is possible to independently control the latent heat capability and the sensible heat capability. Therefore, the interference between the control of the latent heat capability and the control of the sensible heat capability is suppressed, and the temperature and humidity can be controlled with high accuracy.

  The air conditioner according to a second aspect of the present invention is the air conditioner according to the first aspect, wherein the control unit detects the room temperature of the air-conditioned room detected by the room temperature detection unit and the humidity detection unit detects the room temperature. The dew point temperature of the air in the air conditioned room is calculated from the humidity of the air conditioned room, the humidity in the air conditioned room is equal to or higher than the target humidity, and the evaporation temperature detected by the evaporation temperature detecting unit is equal to or higher than the dew point temperature. In this case, the humidity control is prioritized over the temperature control.

  According to the second aspect of the present invention, when the dehumidification is necessary, the controller controls the humidity rather than the temperature control when the evaporation temperature detected by the evaporation temperature detector is equal to or higher than the dew point temperature. Therefore, dehumidification can be performed reliably.

  The air conditioner according to claim 3 of the present invention is the air conditioner according to claim 1 or 2, wherein the control unit converts the humidity in the air-conditioned room detected by the humidity detection unit and the target humidity to absolute humidity. In conversion, ΔX is calculated as absolute humidity.

  According to the third aspect of the present invention, the dehumidification control is performed based on the absolute humidity, so that the problem that occurs in the dehumidification control based on the relative humidity of the intake air can be solved. In dehumidification control based on relative humidity, for example, when the set temperature is higher than the intake temperature, the relative humidity of the intake air is higher than the set humidity set in the relative humidity, but the absolute humidity is the absolute value at the set temperature. The dehumidifying operation is performed when the humidity is lower, that is, when the humidification is originally necessary. Conversely, when the suction temperature is higher than the set temperature, the relative humidity of the intake air is lower than the set humidity, but the absolute humidity is higher than the absolute humidity at the target temperature, that is, when dehumidification is originally required. Even if it exists, dehumidification operation is not performed until the suction temperature decreases and the relative humidity exceeds the set humidity. By performing dehumidification control based on the absolute humidity, the above-described problems such as unnecessary dehumidification and delay of dehumidification control are solved.

  An air conditioner according to a fourth aspect of the present invention is the air conditioner according to any one of the first to third aspects, wherein the controller is configured such that the opening degree of the second indoor expansion valve is the temperature control. When it is the maximum, the opening degree of the outdoor expansion valve is also controlled, and when the second indoor expansion valve is fully closed, the rotation speed of the compressor is also controlled.

  According to the fourth aspect of the present invention, even when the opening degree of the second indoor expansion valve is not adjustable, by controlling the opening degree of the outdoor expansion valve or the rotational speed of the compressor, In the temperature control, the sensible heat capacity can be controlled.

An air conditioner according to a fifth aspect of the present invention is the air conditioner according to any one of the first to fourth aspects, wherein the air conditioner is based on an opening change amount of the second indoor expansion valve in the temperature control. The amount of change in temperature ΔT1 of conditioned air blown out after the air in the air-conditioned room is heat-exchanged with the refrigerant in the indoor heat exchanger by the indoor heat exchanger is calculated, and a predetermined first constant is calculated as ΔT1. The target evaporation temperature is corrected by subtracting the value multiplied by the target evaporation temperature calculated in the humidity control,
Further, based on the change amount of the compressor rotation speed in the humidity control, the temperature change amount ΔT2 of the conditioned air is calculated, and a value obtained by multiplying the ΔT2 by a predetermined second constant is used as the temperature control. The opening change amount is corrected by subtracting from the opening change amount of the second indoor expansion valve calculated in step S2.

  According to the fifth aspect of the present invention, control interference between the rotation speed control of the compressor and the opening control of the second indoor expansion valve is further suppressed, and the temperature and humidity can be controlled more accurately. it can. This is because it is difficult to completely separate the humidity control by the rotational speed control of the compressor and the temperature control by the opening control of the outdoor expansion valve and the second indoor expansion valve. This is because it can be corrected by feedforward control.

  An air conditioner according to a sixth aspect of the present invention is the air conditioner according to any one of the first to fifth aspects, further comprising a blowing temperature detecting unit that detects a blowing temperature of the conditioned air, and the control unit. Calculates a difference ΔTf between the temperature in the air-conditioned room detected by the room temperature detection unit and the outlet temperature, and performs temperature control for controlling the opening degree of the second indoor expansion valve based on the ΔTf and the ΔTr. Do.

  According to the sixth aspect of the invention, in the temperature control, the control unit controls the opening temperature of the second indoor expansion valve based on the ΔTf in addition to the ΔTr. Thus, the temperature control can be performed with higher accuracy.

  The air conditioner according to a seventh aspect of the present invention is the air conditioner according to any one of the first to sixth aspects, wherein the wetness is a ratio of the liquid refrigerant contained in the refrigerant flowing into the suction portion of the compressor. A wetness degree detecting unit for detecting the control, and the control unit performs control to reduce the opening degree of the second indoor expansion valve when the wetness degree exceeds a predetermined upper limit value.

  According to the seventh aspect of the present invention, the controller performs control to reduce the opening of the second indoor expansion valve when the wetness exceeds a predetermined upper limit value. Even when the refrigerant heading from the first indoor heat exchange section to the suction section of the compressor is in a wet state containing liquid refrigerant, as the opening of the second indoor expansion valve is changed in the control. The liquid compression in the suction part can be prevented.

  An air conditioner according to an eighth aspect of the present invention is the air conditioner according to any one of the first to seventh aspects, wherein the outdoor heat exchanger and the outdoor expansion valve are installed outside the air conditioning chamber. The compressor, the first indoor expansion valve, the first indoor heat exchange unit, the second indoor heat exchange unit, and the second indoor expansion valve are accommodated in the air conditioning chamber. It is accommodated in the indoor unit installed inside, and the bypass pipe is branched from the refrigerant circuit in the indoor unit and connected to the refrigerant circuit in the indoor unit.

  According to the invention which concerns on Claim 8, when the said compressor is accommodated in an indoor unit, when the said compressor is accommodated in an outdoor unit, bypass piping provided between an indoor unit and an outdoor unit, It can be connected to the refrigerant circuit in the indoor unit. Therefore, since the number of external pipes can be reduced, the installation workability of the air conditioner is improved. Furthermore, since the pipe length can be shortened, pressure loss and heat loss can be suppressed.

  According to the air conditioner according to the present invention, the dehumidification control based on the rotation speed control of the compressor and the temperature control based on the opening degree control of the second indoor expansion valve can be performed independently. Therefore, interference between both controls can be suppressed, and temperature and humidity can be controlled with high accuracy.

It is a schematic diagram which shows the air conditioner which concerns on Embodiment 1 of this invention. It is a block diagram which shows the functional structure of the air conditioner which concerns on Embodiment 1 of this invention. It is a schematic diagram which shows the air conditioner which concerns on the modification of Embodiment 1. It is a flowchart which shows the dehumidification control in the air conditioner which concerns on Embodiment 1 of this invention. It is a flowchart which shows the temperature control in the air conditioner which concerns on Embodiment 1 of this invention. It is a flowchart which shows temperature control in case a 2nd indoor expansion valve is fully open or fully closed. It is a humid air line figure for demonstrating the reheat dehumidification driving | operation in the air conditioner which concerns on Embodiment 1 of this invention. It is a humid air line figure for demonstrating the reheat dehumidification operation by the air conditioner which performs humidity control based on relative humidity. It is a flowchart which shows the correction | amendment by feedforward control in humidity control. It is a flowchart which shows the correction | amendment by feedforward control in temperature control. It is a block diagram which shows the functional structure of the air conditioner which concerns on Embodiment 2 of this invention. It is a flowchart which shows the temperature control in the air conditioner which concerns on Embodiment 2 of this invention. It is a block diagram which shows the functional structure of the air conditioner which concerns on Embodiment 3 of this invention. In the air conditioner according to Embodiment 3 of the present invention, when the wetness exceeds a predetermined upper limit value, it is a flowchart showing a control for reducing the opening of the second indoor expansion valve. It is a schematic diagram which shows an example of the conventional air conditioner in which reheat dehumidification operation is possible. It is a Mollier diagram which shows the refrigerating cycle at the time of the reheat dehumidification operation | movement of the conventional air conditioner. It is a humid air line figure for demonstrating the state where the reheat capability is insufficient at the time of the reheat dehumidification operation of the conventional air conditioner. It is a schematic diagram which shows the other example of the conventional air conditioner in which reheat dehumidification driving | operation is possible. It is a Mollier diagram which shows the refrigerating cycle at the time of the reheat dehumidification driving | operation of the conventional air conditioner shown in FIG. In the reheat dehumidification operation of the conventional air conditioner shown in FIG. 18, since the reheat capability according to the evaporation capability is obtained, the humid air for explaining that both dehumidification and temperature control are possible. FIG. It is a figure which shows the relationship between the rotation speed of a compressor, the opening degree of a 1st indoor expansion valve (evaporator motor operated valve), sensible heat capability, and latent heat capability. It is a figure which shows the relationship between the opening degree of a 2nd outdoor expansion valve (outdoor unit motor operated valve), sensible heat capability, and latent heat capability.

<Embodiment 1>
Hereinafter, an air conditioner according to Embodiment 1 of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic diagram showing an air conditioner 1 according to Embodiment 1 of the present invention. The air conditioner 1 includes an indoor unit 20, an outdoor unit 30, and a controller 300. The indoor unit 20 is installed in an air conditioning room where air conditioning is performed, and accommodates the first indoor expansion valve 140, the indoor heat exchanger 150, and the second indoor expansion valve 210 therein. The outdoor unit 30 is installed outside the air conditioning room, and accommodates the compressor 110, the outdoor heat exchanger 120, the outdoor expansion valve 130, and the four-way switching valve 160 therein.

  The indoor heat exchanger 150 is, for example, a cross-fin type air-cooled heat exchanger in which fins are attached to the outside of a cooling pipe through which a refrigerant flows. The indoor heat exchanger 150 includes a first indoor heat exchanger 150a that functions as an evaporator during reheat dehumidification operation. And a second indoor heat exchange section 150b that functions as a reheater.

  The compressor 110, the outdoor heat exchanger 120, the outdoor expansion valve 130, the first indoor expansion valve 140, and the first indoor heat exchange unit 150a are connected by a refrigerant pipe to constitute the refrigerant circuit 100. The refrigerant discharged from the compressor circulates through the refrigerant circuit 100.

  The refrigerant circulating in the refrigerant circuit 100 can bypass the outdoor heat exchanger 120 and the outdoor expansion valve 130 by the bypass pipe 200. In the middle of the bypass pipe 200, a second indoor heat exchange section 150b and a second indoor expansion valve 210 are provided.

  The compressor 110 is a scroll compressor provided with, for example, a scroll type compression mechanism. The compressor 110 compresses the low-temperature and low-pressure refrigerant vapor sent from the evaporator (the first indoor heat exchanger 150a during the cooling operation and the reheat dehumidifying operation, and the outdoor heat exchanger 120 during the heating operation). Therefore, use high-temperature and high-pressure refrigerant vapor.

  The outdoor heat exchanger 120 is, for example, a cross-fin type air-cooled heat exchanger in which fins are attached to the outside of a cooling pipe through which refrigerant flows, and exchanges heat between outdoor air and the refrigerant. The outdoor heat exchanger 120 functions as a condenser during cooling operation and reheat dehumidification operation, and functions as an evaporator during heating operation.

  The outdoor expansion valve 130 is a pulse motor drive type electronic expansion valve, for example, and the opening degree can be freely adjusted. The outdoor expansion valve 130 adjusts the refrigerant flow rate to the outdoor heat exchanger 120 that functions as a condenser during cooling operation and reheat dehumidification operation, and flows into the outdoor heat exchanger 120 that functions as an evaporator during heating operation. The refrigerant is squeezed and expanded.

  The first indoor expansion valve 140 is a pulse motor drive type electronic expansion valve, for example, and the opening degree can be freely adjusted. The first indoor expansion valve 140 expands and expands the refrigerant flowing into the first indoor heat exchange unit 150a that functions as an evaporator during cooling operation and reheat dehumidification operation, and functions as a condenser during heating operation. The refrigerant | coolant flow volume to the indoor heat exchange part 150a is adjusted.

  The four-way switching valve 160 switches the flow path of the high-pressure refrigerant vapor discharged from the compressor 110. That is, at the time of cooling operation or reheat dehumidification operation, the high-pressure refrigerant vapor is guided to the outdoor heat exchanger 120 as shown by a solid line, and at the time of heating operation, the high-pressure refrigerant vapor is supplied to the indoor heat exchanger 150 as shown by a broken line. 1 It leads to the indoor heat exchange part 150a.

  The second indoor expansion valve 210 is a pulse motor drive type electronic expansion valve, for example, and the opening degree can be freely adjusted. The second indoor expansion valve 210 adjusts the refrigerant flow rate to the second indoor heat exchange unit 150b that functions as a reheater during the reheat dehumidifying operation. In the example of FIG. 1, the second indoor expansion valve 210 is provided downstream of the second indoor heat exchange unit 150b, but the second indoor expansion valve 210 may be provided upstream of the second indoor heat exchange unit 150b. In the case where it is provided downstream, the liquid refrigerant condensed and reduced in volume in the second indoor heat exchange section 150b passes, so that the expansion valve can be reduced in size. When provided upstream, the gas refrigerant discharged from the compressor 110 passes, so that the expansion valve needs to be enlarged, but the controllability of the refrigerant flow rate can be improved.

  FIG. 2 is a block diagram showing a functional configuration of the air conditioner 1. The air conditioner 1 includes a room temperature detection unit 400, a humidity detection unit 500, and an evaporation temperature detection unit 600 in addition to the configuration shown in FIG.

  The controller 300 includes, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory), and the like, and functions to include a control unit 310, a setting input unit 320, and a time measuring unit 330. The control unit 310 controls the operation of the air conditioner 1 by controlling the rotation speed of the compressor 110, the opening degree of each expansion valve, and the like. The setting input unit 320 includes an input interface for a user to input at least one of a target temperature and a target humidity in air conditioning, and sets the input value as a control target value. The clock unit 330 includes a clock transmitter that generates a clock signal at a constant period, and outputs the clock signal to the control unit 310.

  The room temperature detection unit 400 is, for example, a temperature sensor installed in the vicinity of an unillustrated suction port of the indoor unit 20, and detects the suction temperature Tr that is the temperature of the suction air, that is, the room temperature in the air-conditioned room. The humidity detection unit 500 is, for example, a humidity sensor installed inside the indoor unit 20 and detects the relative humidity of the intake air, that is, the relative humidity in the air-conditioned room.

  The evaporation temperature detection unit 600 detects the evaporation temperature Te of the refrigerant inside the first indoor heat exchange unit 150a that functions as an evaporator during the reheat dehumidification operation. For example, a pressure sensor is provided on the suction side of the compressor 110, and the CPU inside the controller 300 calculates a saturation temperature corresponding to the pressure of the refrigerant gas detected by the pressure sensor and sets it as the evaporation temperature Te. The sensor functions as the evaporation temperature detector 600 together with the CPU. Further, for example, a temperature sensor is provided on the suction side of the compressor 110 or the first indoor heat exchanging unit 150a, and the temperature detected by the temperature sensor is set as the evaporation temperature Te, so that the temperature sensor is connected to the evaporation temperature detecting unit. You may make it function as 600. FIG. This is because there is no practical problem even if the temperature detected by the temperature sensor is regarded as the evaporation temperature Te. That is, when the refrigerant heading from the first indoor heat exchange section 150a toward the suction side of the compressor 111 is in an overheated state, the temperature detected by the temperature sensor is higher than the evaporation temperature Te, but the refrigerant is overheated. This is because the temperature is not large and the temperature detected by the temperature sensor is close to the evaporation temperature Te.

  The air conditioner 1 shown in FIG. 1 is disclosed in Patent Document 1 shown in FIG. 18 in that the refrigerant circulating in the refrigerant circuit 100 can bypass the outdoor heat exchanger 120 and the outdoor expansion valve 130 by the bypass pipe 200. Although it is the same as the conventional air conditioner 9 of description, the connection position of bypass piping and the component provided in bypass piping differ.

  In the air conditioner 9, the bypass pipe 202 is branched from the refrigerant pipe between the four-way switching valve 160 and the outdoor heat exchanger 120 inside the outdoor unit 38, and the first outdoor expansion valve 130, the second indoor expansion valve 170, The refrigerant pipe is connected to the inside of the outdoor unit 38. The second outdoor expansion valve 220 is provided in the middle of the bypass pipe 202, but the second indoor heat exchange unit 150b is not provided.

  In the air conditioner 9, when the local piping is long, the refrigerant condensed in the outdoor heat exchanger 120 during the reheat dehumidification operation is gasified again in the piping up to the second indoor heat exchange section 150b, resulting in a pressure loss. It occurs and the condensation capacity is reduced, so the reheating ability is also reduced.

  On the other hand, in the air conditioner 1, the bypass pipe 200 is branched from the refrigerant pipe between the four-way switching valve 160 and the outdoor heat exchanger 120 inside the outdoor unit 30, and the first outdoor expansion valve 130 and the first indoor expansion valve are branched. 140 is connected to the refrigerant pipe between the indoor unit 20 and the refrigerant pipe. In the middle of the bypass pipe 200, a second outdoor expansion valve 220 and a second indoor heat exchange unit 150b are provided.

  In the air conditioner 1, since the gas refrigerant discharged from the compressor 110 directly flows into the second indoor heat exchange unit 150b, unlike the air conditioner 9, in the pipe to the second indoor heat exchange unit 150b. The reheat capacity is not reduced by the gasification of the refrigerant again.

  FIG. 3 is a schematic diagram illustrating an air conditioner 2 according to a modification of the first embodiment. The air conditioner 2 accommodates the compressor 110 in the indoor unit 21, thereby branching the bypass pipe 201 from the refrigerant circuit 100 in the indoor unit 21 and connecting to the refrigerant circuit 100 in the indoor unit 21. That is, in the air conditioner 2, the bypass pipe 200 provided as an external pipe between the indoor unit 20 and the outdoor unit 30 in the air conditioner 1 shown in FIG. 1 is piped inside the indoor unit 21. The bypass pipe 201 can be used. Therefore, since the bypass pipe does not become an external pipe, the air conditioner 2 is improved in installation workability as compared with the air conditioner 1.

  In addition, the bypass pipe 200 of the air conditioner 1 that is an external pipe has a long pipe length under the installation conditions where the distance between the indoor unit 20 and the outdoor unit 30 is long, but the bypass pipe 201 of the air conditioner 2 is Since the pipe is piped inside the indoor unit 21, the pipe length is constant regardless of the distance between the indoor unit 21 and the outdoor unit 31. Therefore, the air conditioner 2 in which the bypass pipe 201 is piped inside the indoor unit 21 has a reduced reheat capacity that occurs when the bypass pipe has a long pipe length, that is, the high pressure / high temperature discharged from the compressor 110. It is possible to avoid a decrease in reheating capacity due to pressure loss and heat loss of the gas refrigerant.

  In the air conditioners 1 and 2 according to the first embodiment of the present invention, the increase / decrease in the latent heat capacity related to the dehumidification control is made by the control unit 310 performing PI control on the rotational speed of the compressor 110, and the sensible heat related to the temperature control. The increase / decrease in the capacity is performed by the controller 310 performing PI control on the opening degrees of the outdoor expansion valve 130 and the second indoor expansion valve 210. That is, although the latent heat capability control (dehumidification control) and the sensible heat capability control (temperature control) are performed simultaneously, they are performed independently of each other.

  In addition, when the humidity in the air-conditioned room is equal to or higher than the target humidity, that is, dehumidification is required, the control unit 310 detects the room temperature in the air-conditioned room detected by the room temperature detecting unit 400 and the humidity in the air-conditioned room detected by the humidity detecting unit 500. , The dew point temperature D of the air in the air-conditioned room is calculated, and when the evaporation temperature Te detected by the evaporation temperature detection unit 600 is equal to or higher than the dew point temperature D, the humidity control is prioritized over the temperature control. This is because dehumidification cannot be performed unless the evaporation temperature Te is lower than the dew point temperature D. Dehumidification control in the air conditioners 1 and 2 will be described below.

  FIG. 4 is a flowchart showing dehumidification control in the air conditioners 1 and 2. Control unit 310 starts a timer having the sampling interval of the suction temperature and the suction humidity as a set time (step S1). The timer count is performed based on a clock signal generated by the timer 330. Next, the control unit 310 detects the set temperature Ts and the set humidity Hs set by the setting input unit 320 (step S2), and calculates the target absolute humidity Xs based on Ts and Hs. The room temperature detector 400 detects the suction temperature, and the humidity detector 500 detects the suction humidity (step S4). Based on the detected suction temperature and suction humidity, control unit 310 calculates suction absolute humidity X and dew point temperature D (steps S5 and S6), and calculates a difference ΔX (= Xs−X) between Xs and X. Calculate (step S7). If the suction absolute humidity X is equal to or lower than the target absolute humidity Xs (NO in step S8), the dehumidification is unnecessary and the process returns to step S1. When the absolute suction humidity X exceeds the target absolute humidity Xs (YES in step S8), the control unit 310 calculates the target evaporation temperature TeS based on ΔX (step S9). Subsequently, the evaporation temperature detection unit 600 detects the evaporation temperature Te (step S10). The controller 310 compares Te and D (step S11), and when the evaporation temperature Te is equal to or higher than the dew point temperature D (YES in step S11), gives priority to dehumidification control over temperature control (step S12). The temperature control will be described in detail later. When the evaporation temperature Te is lower than the dew point temperature D (NO in step S11), the process proceeds to step S13.

  The control unit 310 compares TeS and Te, and when Te is larger than a value obtained by adding 0.5 ° C., which is a dead zone of the rotation speed control of the compressor 110, to TeS (YES in step S13), In order to lower the evaporation temperature, the rotational speed of the compressor 110 is increased (step S14). When Te is less than or equal to TeS + 0.5 (NO in step S13), if Te is in the range of TeS ± 0.5 (YES in step S15), since Te is within the target range, control unit 310 The rotation speed of the compressor 110 is maintained (step S16). If Te is less than TeS−0.5 (NO in step S15), the controller 310 decreases the rotational speed of the compressor 110 to increase the evaporation temperature Te (step S17). Control unit 310 maintains this state until the timer count ends (NO in step S18). When the timer count ends (YES in step S18), control unit 310 returns to step S1 and newly starts the timer. .

  FIG. 5 is a flowchart showing temperature control in the air conditioners 1 and 2. The controller 310 starts a timer with the same set time as the humidity control shown in FIG. 4 (step S101). Temperature control and humidity control are started at the same time. Next, the control unit 310 detects the set temperature Ts set by the setting input unit 320 (step S102). The room temperature detector 400 detects the suction temperature Tr (step S103). The controller 310 calculates a difference ΔTr (= Ts−Tr) between Ts and Tr (step S104).

  If the dead zone of the opening control of the second indoor expansion valve 210 is, for example, 0.1 ° C., and ΔTr is in the range of 0 ± 0.1 (YES in step S105), the room temperature is within the target range. The control unit 310 maintains the opening degree of the second indoor expansion valve 210 (step S106). When ΔTr is larger than 0.1, that is, when the suction temperature Tr is lower than the set temperature Ts (YES in step S107), the refrigerant to the second indoor heat exchange unit 150b functioning as a reheater. In order to increase the flow rate and increase the reheating capability of the second indoor heat exchange unit 150b to raise the room temperature, the control unit 310 increases the opening of the second indoor expansion valve 210 (step S108). When ΔTr is smaller than −0.1, that is, when the suction temperature Tr is higher than the set temperature Ts (NO in step S107), the refrigerant flow rate to the second indoor heat exchange unit 150b is decreased, and the second In order to reduce the reheat capability of the indoor heat exchange unit 150b and lower the room temperature, the control unit 310 decreases the opening of the second indoor expansion valve 210 (step S109). Control unit 310 maintains this state until the timer count ends (NO in step S110). When the timer count ends (YES in step S110), control unit 310 returns to step S101 to newly start the timer. .

  In the above temperature control, even when ΔTr is smaller than −0.1, when the second indoor expansion valve 210 is fully closed, the refrigerant flow rate to the second indoor heat exchange section 150b can be reduced. Since it is not possible to reduce the reheat capability of the second indoor heat exchange unit 150b, conversely, even when ΔTr exceeds 0.1, when the second indoor expansion valve 210 is fully open, Since the refrigerant flow rate to the second indoor heat exchange unit 150b cannot be increased, the reheat capability of the second indoor heat exchange unit 150b cannot be increased. FIG. 6 shows the temperature control in such a case.

  FIG. 6 is a flowchart showing temperature control when the second indoor expansion valve 210 is fully opened or fully closed. Since the flowchart shown in FIG. 5 and step 105 are the same, only step 105 and subsequent steps in FIG. 5 are shown in FIG.

  When ΔTr is in the range of 0 ± 0.1 (YES in step S105), the process proceeds to the circled number 1 in FIG. When ΔTr is larger than 0.1 (YES in step S107), when the second indoor expansion valve 210 is fully opened (YES in step S201), the refrigerant flow rate to the outdoor heat exchanger 120 is decreased to reduce the second indoor expansion valve 210. In order to increase the refrigerant flow rate to the second indoor heat exchange unit 150b and increase the reheat capability of the second indoor heat exchange unit 150b to raise the room temperature, the opening degree of the outdoor expansion valve 130 is decreased (step S202). When the second indoor expansion valve 210 is not fully opened (NO in step S201), the process proceeds to the circled number 2 in FIG.

  When ΔTr is smaller than −0.1 (NO in step S107), when second indoor expansion valve 210 is fully closed (YES in step S203), in order to lower the room temperature by increasing the sensible heat capacity The rotation speed of the compressor 110 is increased (step S204). When the second indoor expansion valve 210 is not fully closed (NO in step S203), the process proceeds to the circled numeral 3 in FIG. Control unit 310 maintains this state until the timer count ends (NO in step S205), and when the timer count ends (YES in step S205), it returns to circled number 4 in FIG. A new start.

  FIG. 7 is a moist air diagram for explaining the reheat dehumidifying operation in which the control of the above embodiment is performed. A point (set temperature Ts, target absolute humidity Xs) as a control target when the set room temperature is Ts and the set relative humidity is Hs is indicated by a point 0. The state of the intake air before the air conditioning at the temperature Tr and the absolute humidity X is performed is indicated by a point 1. In this example, both Tr and X are higher than Ts and Xs.

  The dehumidification control is started, the target evaporation temperature TeS is set based on the difference ΔX between X and Xs, and the rotation speed of the compressor 110 is increased or decreased according to the difference between the actual evaporation temperature Te and TeS. (See FIG. 4), the state of the intake air changes from the point 0 to the point a on the saturated air line as the temperature decreases, and descends on the saturated air line to decrease the absolute humidity, from the point a to the point b. And further change.

  Based on the difference ΔTr between Tr and Ts, the temperature of the second indoor expansion valve 210 is increased and decreased (see FIG. 5), and the temperature rises from point b to point c (point 0). The state further changes, the intake air is blown out as conditioned air, and the air in the air-conditioned room is set to the control target value temperature Ts and absolute humidity Xs.

  Here, it is assumed that the temperature and absolute humidity increase due to the indoor load, and the state changes from point c to point 1. At this time, since the control amounts of the compressor 110 and the second indoor expansion valve 210 that are PI-controlled are changed and both the latent heat capacity and the sensible heat capacity are increased, the state of the intake air as described below Change will be different.

  By the dehumidification control, the intake air in the state of point 1 changes to the state of point a on the saturated air line, and then descends on the saturated air line to lower the absolute humidity, and the temperature and absolute humidity are lower than point b. It changes to the state of b2. And by temperature control, temperature rises from the state of the point b2, and changes to the state of the point c2. The temperature and absolute humidity rise from the point c2 due to the indoor load, and the absolute humidity changes from point 1 to point d2, which is closer to point 0 than point 1.

  The air in the air-conditioned room in the state of the point d2 is lowered on the saturated air line after the temperature is lowered by dehumidification control and the state is changed to the point a2 on the saturated air line (absolute humidity is lower than a). The absolute humidity decreases and changes to a state of b3 where the temperature and absolute humidity are lower than the state of point b2. And by temperature control, temperature rises from the state of the point b3 and changes to the state of the point c3. The temperature and absolute humidity rise from the state of the point c3 due to the indoor load, change to the point d3 where the absolute humidity is equal to the point 0 and the absolute humidity is low, and the dehumidification control is completed. Further, the temperature control is ended by heating from the state of d3 to the point 0 by the indoor load.

  In the present embodiment, as described above, the increase or decrease in the latent heat capacity related to the dehumidification control is made by the control unit 310 controlling the rotation speed of the compressor 110 based on the target evaporation temperature TeS. The heat capacity is increased or decreased by the control unit 310 controlling the opening degrees of the outdoor expansion valve 130 and the second indoor expansion valve 210 based on ΔTr. That is, the control of the latent heat capability and the control of the sensible heat capability are performed independently. Therefore, the interference between the control of the latent heat capability and the control of the sensible heat capability is suppressed, and the temperature and humidity can be controlled with high accuracy.

  In the present embodiment, as described above, the control unit 310 gives priority to humidity control over temperature control when the evaporation temperature Te detected by the evaporation temperature detection unit 600 is equal to or higher than the dew point temperature D. Dehumidification is surely performed.

Further, in the present embodiment, as described above, the controller 310 controls the opening of the outdoor expansion valve 130 when the opening of the second indoor expansion valve 210 is maximum in the temperature control, When the second indoor expansion valve 210 is fully closed, the number of rotations of the compressor 110 is controlled. Therefore, temperature control can be performed even when the opening degree of the second indoor expansion valve 210 is not adjustable.

  By the way, the air conditioners 1 and 2 which concern on the said embodiment are performing humidity control not based on relative humidity but absolute humidity as demonstrated above based on FIG. 4 and FIG. A problem in the case of performing humidity control based on the relative humidity and an advantage in the case of performing humidity control based on the absolute humidity will be described below.

  FIG. 8 is a wet air diagram for explaining a reheat dehumidifying operation by an air conditioner that performs humidity control based on relative humidity. A point that is a control target when the set room temperature is Ts and the set relative humidity is Hs is indicated by a point 0. The state of the intake air is a state where the temperature is lower than the set temperature Ts and the absolute humidity is equal to the point 0, that is, a state where the temperature is lower than the set temperature Ts and the relative humidity is higher than the set relative humidity Hs. , Absolute humidity X1 = Xs). The state of the intake air is higher than the set temperature Ts and the absolute humidity is higher than the point 0, but the relative humidity is lower than the set relative humidity Hs at a point 2 (temperature Tr2, absolute humidity X2).

  When the state of the intake air is at point 1, the air conditioner that performs humidity control based on the relative humidity determines that dehumidification is necessary because the relative humidity is higher than Hs. As a result, the intake air is cooled below the dew point to dehumidify (from point 1 to point a) and overheated by the reheater (from point a to point b). As a result of unnecessary dehumidification, although only reheating is required, the relative humidity becomes lower than the set relative humidity Hs.

  When the state of the intake air is at point 2, in an air conditioner that performs humidity control based on relative humidity, the relative humidity is higher than Hs until the room temperature of the air-conditioned room is reduced from Tr2 to Tr2 ′ by temperature control. It is judged that dehumidification is unnecessary because it is low. Accordingly, since the start of the dehumidifying operation is delayed, it takes time until the humidity reaches Hs.

  On the other hand, in the air conditioners 1 and 2 that perform humidity control based on absolute humidity, when the state of the intake air is at point 1, no dehumidification is performed, and when the state of the intake air is at point 2, temperature control is performed. At the same time, the humidity control is performed, so that the time until the humidity reaches Hs is shortened as compared with the conventional air conditioner. That is, problems of the air conditioner that performs humidity control based on relative humidity, such as unnecessary dehumidification and delay of dehumidification control, are solved.

  In the air conditioners 1 and 2 according to the first embodiment, the latent heat capacity control (dehumidification control) by increasing / decreasing the rotation speed of the compressor 110 and the manifestation by increasing / decreasing the opening degrees of the outdoor expansion valve 130 and the second indoor expansion valve 210 are demonstrated. Control of heat capacity (temperature control) is performed independently of each other. However, an increase or decrease in the rotational speed of the compressor 110 also affects the sensible heat capacity, and an increase or decrease in the opening degree of the outdoor expansion valve 130 and the second indoor expansion valve 210 also affects the latent heat capacity. Therefore, it is difficult to make the control of the latent heat capability (dehumidification control) and the control of the sensible heat capability (temperature control) completely independent. Therefore, the mutual interference of control is corrected by feedforward control in the air conditioners 1 and 2.

  Correction by feedforward control in humidity control and temperature control will be described with reference to FIGS. 9 and 10.

  FIG. 9 is a flowchart showing correction by feedforward control in humidity control. When the opening degree of second indoor expansion valve 210 is changed (YES in step S301), control unit 310 calculates reheat amount change amount ΔQr based on the opening degree of second indoor expansion valve 210 before and after the change. (Step S302). Based on ΔQr, control unit 310 calculates change amount ΔT1 of blowing temperature Tf (step S303). The control unit 310 calculates a value obtained by multiplying ΔT1 by a predetermined constant C1 from the target evaporation temperature TeS calculated based on the difference ΔX between the target absolute humidity Xs and the suction absolute humidity X (see step S8 in FIG. 4). Is subtracted to correct TeS (step S304). The correction value is reset as the target evaporation temperature TeS, and the controller 310 performs the dehumidification control shown in the flowchart of FIG. Deviation can be prevented.

  FIG. 10 is a flowchart showing correction by feedforward control in temperature control. When the rotation speed of the compressor 110 is changed (YES in step S401), the control unit 310 changes the evaporation temperature based on the evaporation temperature Te detected by the evaporation temperature detection unit 600 before and after the rotation speed change of the compressor 110. The amount ΔTe is calculated (step S402). Based on ΔTe, control unit 310 calculates change amount ΔT2 of blowing temperature Tf (step S403). The control unit 310 determines a predetermined constant C1 from the opening of the second indoor expansion valve 210 calculated based on the difference ΔTr between the set temperature Ts and the suction temperature Tr (see step S104 to step 109 in FIG. 5). The value obtained by multiplying ΔT2 by 1 is subtracted to correct the opening of the second indoor expansion valve 210 (step S404). The correction value is reset as the opening degree of the second indoor expansion valve 210, and the control unit 310 performs the temperature control shown in the flowchart of FIG. 5 so that the temperature generated by the rotation speed change of the compressor 110 in the humidity control. Control deviation can be prevented.

<Embodiment 2>
FIG. 11 is a block diagram showing a functional configuration of the air conditioner 3 according to Embodiment 2 of the present invention. In addition to the configuration of the air conditioner 1 or 2 according to the first embodiment, the air conditioner 3 further includes an outlet temperature detection unit 700. The blowing temperature detection unit 700 is, for example, a temperature sensor installed in the vicinity of an unillustrated air outlet of the indoor unit 20, and is blown out by heat exchange with the refrigerant in the indoor heat exchanger 150 by the indoor heat exchanger 150. The temperature Tf of the conditioned air that is the air in the air-conditioned room is detected. In the air conditioner 3, in the temperature control, the control unit 310 calculates the difference ΔTf between the blowing temperature Tf and the suction temperature Tr, and based on not only the difference ΔTr between the set temperature Ts and the suction temperature Tr but also ΔTf. Thus, the air conditioners 1 and 2 are different in that the opening degree of the second indoor expansion valve 210 is controlled.

  When the room temperature (suction temperature Tr) in the air-conditioned room is lower than the set temperature Ts, in order to raise the room temperature to the set temperature Ts, the control unit 310 generates conditioned air at a blow-off temperature Tf higher than the set temperature Ts. Need to blow out. In other words, the relationship between the blowout temperature Tf, the set temperature Ts, and the suction temperature Tr is Tf> Ts> Tr. On the other hand, when the room temperature in the air-conditioned room exceeds the set temperature Ts, the control unit 310 causes the conditioned air to be blown out at a blowing temperature Tf lower than the set temperature Ts in order to lower the room temperature to the set temperature Ts. There is a need. That is, the relationship between the blowout temperature Tf, the set temperature Ts, and the suction temperature Tr is Tf <Ts <Tr.

  However, in the temperature control, when the room temperature in the air-conditioned room is lower than the set temperature Ts (ΔTr> 0.1), ΔTf becomes extremely larger than ΔTr, or the room temperature in the air-conditioned room exceeds the set temperature Ts ( It is not preferable that ΔTf is extremely smaller than ΔTr when ΔTr <−0.1). This is because overshoot may occur in the temperature control.

  In order to prevent such an overshoot, the control unit 310 calculates based on ΔTr when the difference between ΔTf and ΔTr exceeds a predetermined threshold Th1 when the room temperature in the air-conditioned room is lower than the set temperature Ts. When the room temperature in the air-conditioned room is corrected to reduce the amount of increase in the opening degree of the second expansion valve 210 and exceeds the set temperature Ts, when the difference between ΔTf and ΔTr is below a predetermined threshold Th2, it is based on ΔTr. Correction for reducing the opening reduction amount of the second expansion valve 210 calculated in the above is performed.

  FIG. 12 is a flowchart showing the temperature control in the air conditioner 3. In addition, the same code | symbol is attached | subjected about the step same as the said temperature control in the air conditioner 1 or 2 which concerns on Embodiment 1 shown in FIG. 5, and description is abbreviate | omitted unless it is required.

  In the temperature control in the air conditioner 3, step S501 in which the blowing temperature detecting unit 700 detects the blowing temperature Tf is added between step S101 and step S104. Between step S104 and step S105, step S502 in which the control unit 310 calculates a difference ΔTf between the blowing temperature Tf and the suction temperature Tr is added.

  If ΔTr calculated by control unit 310 in step S104 is greater than 0.1, that is, if suction temperature Tr is lower than set temperature Ts (YES in step S107), control unit 310 determines based on ΔTr. An opening increase amount of the second indoor expansion valve 210 is calculated (step S503). When the difference between ΔTf and ΔTr exceeds a predetermined threshold Th1 (YES in step S504), control unit 310 performs correction to reduce the opening increase amount of second expansion valve 210 calculated in step S503 ( In step S505, the opening degree of the second indoor expansion valve 210 is increased by the corrected opening degree increase amount (step S108). On the other hand, when the difference between ΔTf and ΔTr is equal to or smaller than a predetermined threshold Th1 (NO in step S504), control unit 310 uses the second opening amount of second expansion valve 210 calculated in step S503 as the second indoor expansion valve. The opening degree of 210 is increased (step S108).

  When ΔTr is smaller than −0.1, that is, when suction temperature Tr is higher than set temperature Ts (NO in step S107), control unit 310 opens second indoor expansion valve 210 based on ΔTr. The degree of decrease is calculated (step S506). When the difference between ΔTf and ΔTr falls below a predetermined threshold Th2 (YES in step S507), control unit 310 performs a correction to reduce the opening reduction amount of second expansion valve 210 calculated in step S503 ( Step S507), the opening degree of the second indoor expansion valve 210 is decreased by the corrected opening degree reduction amount (Step S109). On the other hand, when the difference between ΔTf and ΔTr is equal to or greater than a predetermined threshold Th2 (NO in step S507), control unit 310 uses the second opening valve 210 to reduce the second indoor expansion valve based on the opening reduction amount of second expansion valve 210 calculated in step S506. The opening degree of 210 is decreased (step S108).

  Operations after Step S105, Step S108, and Step S109 are the same as the temperature control in the air conditioner 1 or 2 according to Embodiment 1 shown in FIG.

  According to the air conditioner 3 according to the second embodiment, in the temperature control, the control unit 310 also calculates the difference ΔTf between the blowing temperature Tf and the suction temperature Tr in addition to the difference ΔTr between the set temperature Ts and the suction temperature Tr. Since the opening degree of the second indoor expansion valve 210 is controlled based on this, the blow-out temperature Tf can be managed, and the temperature control can be performed with higher accuracy.

<Embodiment 3>
FIG. 13 is a block diagram showing a functional configuration of the air conditioner 4 according to Embodiment 3 of the present invention. The air conditioner 4 further includes a wetness detection unit 800 in addition to the configuration of the air conditioner 1 or 2 according to the first embodiment. The wetness detection unit 800 detects the wetness that is the ratio of the liquid refrigerant contained in the refrigerant flowing into the suction unit of the compressor 110. For example, a temperature sensor is provided on the discharge side of the compressor 110, and the CPU inside the controller 300 calculates the wetness based on the temperature (superheat degree) of the discharge gas refrigerant detected by the temperature sensor. The temperature sensor functions as the wetness detection unit 800 together with the CPU. The control unit 310 performs control (hereinafter referred to as wetness control) to reduce the opening degree of the second indoor expansion valve 210 when the wetness degree exceeds a predetermined upper limit value.

  FIG. 14 is a flowchart showing wetness control in the air conditioner 4. The controller 310 starts a timer with the same set time as the humidity control and the temperature control (step S501). The wetness control is started simultaneously with the temperature control and the humidity control. Next, the wetness detection unit 800 detects the wetness of the suction unit of the compressor 110 (step S502). If the wetness is less than or equal to the upper limit value (NO in step S503), the wetness is within the allowable range, so the process returns to step S501. When the wetness exceeds the upper limit value (YES in step S503), the process proceeds to step S504, and the control unit 310 decreases the opening of the second indoor expansion valve 210. Control unit 310 maintains this state until the timer count ends (NO in step S505). When the timer count ends (YES in step S505), control unit 310 returns to step S501 to newly start the timer. .

  According to the air conditioner 4 according to the third embodiment, the control unit 310 reduces the opening degree of the second indoor expansion valve 210 by the wetness control when the wetness degree exceeds a predetermined upper limit value. Even when the suction portion of the compressor 110 becomes wet with the change in the opening of the second indoor expansion valve 210 in the temperature control, liquid compression in the suction portion can be prevented.

  As described above, the air conditioners 1 to 4 according to the first to third embodiments of the present invention have been described. However, the present invention is not limited to these embodiments, and various modifications and improvements can be made without departing from the spirit of the present invention. For example, the following modified embodiment can be adopted.

  (1) In the above embodiment, when the second indoor expansion valve 210 is fully opened, the outdoor expansion valve 130 is controlled after the second indoor expansion valve 210 is fully opened, but both expansion valves are controlled simultaneously. And you may change the refrigerant | coolant amount which flows in into the 2nd indoor heat exchange part 150b.

  (2) In the above embodiment, the bypass pipe 200 is connected to the refrigerant pipe between the first outdoor expansion valve 130 and the first indoor expansion valve 140, but the bypass pipe 200 is connected to the first indoor expansion valve 140. And a refrigerant pipe between the first indoor heat exchanger 150a. According to this configuration, the refrigerant condensed in the second indoor heat exchange unit 150b is not the refrigerant pipe through which the high-pressure liquid refrigerant condensed in the outdoor heat exchanger 120 flows, but the high-pressure liquid refrigerant is the first indoor expansion valve 140. And flows into the refrigerant pipe through which the refrigerant in a state where the pressure is reduced due to the expansion of the flow. Therefore, since the pressure difference of the refrigerant | coolant in the inlet_port | entrance and exit of the 2nd indoor heat exchange part 150b can be enlarged, the refrigerant | coolant flow rate inside the 2nd indoor heat exchange part 150b can be increased. Therefore, the reheat capability of the second indoor heat exchange unit 150b can be increased.

  (3) Although the air conditioner 4 which concerns on the said Embodiment 3 adds the wetness degree detection part 800 to the structure of the air conditioner 1 or 2 which concerns on the said Embodiment 1, it concerns on the said Embodiment 2. It is also possible to add a wetness detection unit 800 to the configuration of the air conditioner 3.

  (4) In the above embodiment, the compressor 110 is a scroll compressor, but the compression mechanism of the compressor is not limited to the scroll type, and a compression mechanism different from a scroll compressor such as a rotary compressor, for example. It may be a compressor provided with.

1-4 Air Conditioner 20, 21 Indoor Unit 30, 31 Outdoor Unit 100 Refrigerant Circuit 110 Compressor 120 Outdoor Heat Exchanger 130 Outdoor Expansion Valve 140 First Indoor Expansion Valve 150 Indoor Heat Exchanger 150a First Indoor Heat Exchanger 150b Second indoor heat exchange section 200, 201 Bypass piping 210 Second indoor expansion valve 300 Controller 310 Control section 320 Setting input section 400 Temperature detection section 500 Humidity detection section 600 Evaporation temperature detection section 700 Blowing temperature detection section 800 Wetness detection section

Claims (8)

An indoor heat exchanger (150) including a first indoor heat exchange section (150a) that functions as an evaporator during reheat dehumidification operation, and a second indoor heat exchange section (150b) that functions as a reheater;
The compressor (110), the outdoor heat exchanger (120), the outdoor expansion valve (130) whose opening is adjustable, the first indoor expansion valve (140) whose opening is adjustable, and the indoor heat exchanger (150) A refrigerant circuit (100) in which the first indoor heat exchange section (150a) circulates in the circuit connected by the refrigerant pipe;
Bypassing the outdoor heat exchanger (120) and the outdoor expansion valve (130) of the refrigerant circuit (100), the second indoor heat exchanger (150b) of the indoor heat exchanger (150), and the opening degree A bypass pipe (200, 201) which is a refrigerant pipe provided with an adjustable second indoor expansion valve (210) in the middle;
A room temperature detector (400) for detecting the room temperature of the air-conditioned room where the air conditioning is performed;
A humidity detector (500) for detecting the humidity of the air-conditioned room;
A setting input unit (320) for an operator to input at least one of a target temperature and a target humidity in air conditioning;
An evaporation temperature detection unit (600) for detecting the evaporation temperature of the refrigerant passing through the first indoor heat exchange unit (150a);
A controller (310) for controlling the compressor (110), the outdoor expansion valve (130), the first indoor expansion valve (140), and the second indoor expansion valve (210),
The control unit (310)
A difference ΔX between the humidity in the air-conditioned room detected by the humidity detection unit (500) and the target humidity is calculated, a target evaporation temperature that is a target value of the evaporation temperature is set based on the ΔX, and the target evaporation temperature Dehumidification control to control the rotation speed of the compressor (110) based on
A difference ΔTr between the temperature in the air-conditioned room detected by the room temperature detection unit (400) and the target temperature is calculated, and temperature control is performed to control the opening degree of the second indoor expansion valve (210) based on the ΔTr. Air conditioner.   The control unit (310) determines the dew point temperature of the air in the air-conditioned room from the room temperature of the air-conditioned room detected by the room temperature detector (400) and the humidity of the air-conditioned room detected by the humidity detector (500). When the humidity in the air-conditioned room is equal to or higher than the target humidity and the evaporation temperature detected by the evaporation temperature detection unit (600) is equal to or higher than the dew point temperature, the humidity control is performed rather than the temperature control. The air conditioner according to claim 1, which is performed with priority.   3. The control unit (310) according to claim 1, wherein the control unit (310) converts the humidity in the air-conditioned room detected by the humidity detection unit (500) and the target humidity into an absolute humidity, and calculates the ΔX as an absolute humidity. Air conditioner.   In the temperature control, when the opening degree of the second indoor expansion valve (210) is the maximum, the control unit (310) also controls the opening degree of the outdoor expansion valve (130), and The air conditioner according to any one of claims 1 to 3, wherein when the two-indoor expansion valve (210) is fully closed, the number of rotations of the compressor (110) is also controlled. The control unit (310)
Based on the degree of opening change of the second indoor expansion valve (210) in the temperature control, the air in the air-conditioned room is heated by the indoor heat exchanger (150) with the refrigerant and heat inside the indoor heat exchanger (150). By calculating the blowing temperature change amount ΔT1 of the conditioned air that is exchanged and blown, and subtracting a value obtained by multiplying the predetermined first constant by ΔT1 from the target evaporation temperature calculated in the humidity control, Correct the target evaporation temperature,
And based on the change amount of the compressor (110) rotation speed in the humidity control, the conditioned air blowing temperature change amount ΔT2 is calculated, and a value obtained by multiplying the ΔT2 by a predetermined second constant is The air conditioner according to any one of claims 1 to 4, wherein the opening change amount is corrected by subtracting from the opening change amount of the second indoor expansion valve (210) calculated in the temperature control. An air temperature detector (700) for detecting the air temperature of the conditioned air;
The control unit (310) calculates a difference ΔTf between the temperature in the air-conditioned room detected by the room temperature detection unit (400) and the blowing temperature, and the second indoor expansion valve based on the ΔTf and the ΔTr. The air conditioner according to any one of claims 1 to 5, wherein temperature control for controlling the opening degree of (210) is performed. A wetness degree detection unit (800) that detects a wetness degree that is a ratio of the liquid refrigerant contained in the refrigerant flowing into the suction part of the compressor (110);
The said control part (310) performs control which reduces the opening degree of a said 2nd indoor expansion valve (210), when the said wetness degree exceeds the predetermined upper limit. The air conditioner described in the paragraph. The outdoor heat exchanger (120) and the outdoor expansion valve (130) are accommodated in an outdoor unit (31) installed outside the air conditioning room,
The compressor (110), the first indoor expansion valve (140), the first indoor heat exchange unit (150a), the first indoor heat exchange unit (150b), and the second indoor expansion valve (210 ) Is housed in an indoor unit (21) installed inside the air conditioning room,
The bypass pipe (201) is branched from the refrigerant circuit (100) in the indoor unit (21) and connected to the refrigerant circuit (100) in the indoor unit (21). The air conditioner of any one of Claims.

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