JP2013104619A - Air conditioning indoor unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a power consumption for operating an indoor fan without hindering functions of preventing dew condensation, concerning an air conditioning indoor unit.SOLUTION: When an indoor air is cooled by heat exchange using an indoor heat exchanger 42, the indoor air is ventilated to the indoor heat exchanger 42 by the indoor fan 43. An indoor controller 47 controls the indoor fan 43. In the control of the indoor fan 43, the indoor controller 47 decides whether to change a lower limit of a rotating speed of the indoor fan 43 at least on the basis of an evaporation temperature of the indoor heat exchanger 42.

Description

  The present invention relates to an air conditioning indoor unit, and more particularly to an air conditioning indoor unit having a function of cooling a room.

  The air conditioning indoor unit blows air from the indoor fan to the indoor heat exchanger (evaporator) during cooling, and blows out the indoor air cooled by the indoor heat exchanger from the outlet. Since the cooled indoor air cools the periphery of the air outlet of the air conditioning indoor unit from the room temperature around the casing of the air conditioning indoor unit, condensation easily occurs around the air outlet. Therefore, operation control of the air conditioning indoor unit is performed so that condensation does not occur around the air outlet of the air conditioning indoor unit. For example, an operating condition for maintaining the rotation speed of the indoor fan at a certain value or more so as not to cause condensation is set, or as described in Patent Document 1 (Japanese Patent Laid-Open No. 2003-106619), condensation is performed. When the occurrence of this is detected, the operating condition of the air-conditioning indoor unit may be changed to a condition in which condensation is less likely to occur than a preset condition.

  Incidentally, in recent years, there has been a demand for air-conditioning indoor units with low power consumption, but the power consumption of the air-conditioning indoor units may increase depending on the operating conditions for preventing condensation.

  The subject of this invention is reducing the power consumption which concerns on a driving | operation of an indoor fan, without impairing the function of dew condensation prevention in an air-conditioning indoor unit.

  An air conditioning indoor unit according to a first aspect of the present invention controls an indoor heat exchanger that cools indoor air by heat exchange, an indoor fan that blows indoor air to the indoor heat exchanger, an indoor fan, A controller that determines whether or not to change the lower limit value of the rotational speed of the fan based on at least the evaporation temperature of the indoor heat exchanger.

  In the air conditioning indoor unit according to the first aspect, the control device controls the indoor fan, and whether the control device changes the lower limit value of the rotation speed of the indoor fan in the control of the indoor fan, at least the evaporation of the indoor heat exchanger. Judge based on temperature. Therefore, when the evaporation temperature satisfies a condition that does not cause condensation due to room air after heat exchange, the lower limit value of the rotation speed of the indoor fan can be lowered. Thereby, the rotation speed of the indoor fan can be reduced without impairing the function of preventing condensation.

  An air conditioning indoor unit according to a second aspect of the present invention is the air conditioning indoor unit according to the first aspect, wherein a casing that houses the indoor heat exchanger and the indoor fan, and an indoor temperature that detects the temperature of the indoor air around the casing. And a controller that calculates the indoor dew point temperature based on the temperature of the indoor air around the casing and determines whether or not to change the lower limit value of the rotational speed of the indoor fan. Judgment based on the evaporating temperature of the exchanger.

  In the air conditioning indoor unit according to the second aspect, the control device can calculate the indoor dew point temperature that changes due to a temperature change around the casing, and can change the lower limit value of the rotational speed based on the indoor dew point temperature.

  An air conditioning indoor unit according to a third aspect of the present invention is the air conditioning indoor unit according to the second aspect, further comprising an indoor humidity detector that detects the humidity of the indoor air around the casing, and the control device The indoor dew point temperature is calculated based on the temperature and humidity of the indoor air, and whether or not the lower limit value of the rotation speed of the indoor fan is changed is determined based on the indoor dew point temperature and the evaporation temperature of the indoor heat exchanger. .

  In the air conditioning indoor unit pertaining to the third aspect, the indoor dew point temperature can be calculated more accurately because the control device calculates the indoor dew point temperature from the ambient temperature and humidity of the casing.

  An air conditioning indoor unit according to a fourth aspect of the present invention is the air conditioning indoor unit according to any one of the first to third aspects, wherein the air conditioning indoor unit is connected to the external air conditioner, and the control device is provided from the external air conditioner. The indoor dew point temperature is predicted based on the obtained data.

  In the air conditioning indoor unit according to the fourth aspect, the dew point temperature is predicted based on the data of the external air conditioner to determine whether to change the lower limit value of the rotation speed of the indoor fan. Even if omitted, it is possible to sufficiently reduce power consumption while sufficiently preventing the occurrence of condensation.

  In the air conditioning indoor unit according to the first aspect, it is possible to reduce power consumption by reducing the number of rotations of the indoor fan as compared with the conventional one while preventing the occurrence of condensation.

  In the air conditioner indoor unit according to the second aspect, since the lower limit value of the rotation speed of the indoor fan can be controlled according to the temperature change around the casing, the function of reducing power consumption without causing condensation is improved. .

  In the air conditioning indoor unit according to the third aspect, control for reducing power consumption without causing condensation can be performed more accurately, and the function of reducing power consumption can be enhanced.

  In the air conditioning indoor unit according to the fourth aspect, it is possible to form a configuration that reduces power consumption by reducing the number of revolutions of the indoor fan while preventing the occurrence of condensation.

The figure which shows the refrigerant | coolant piping system of the air conditioning apparatus containing the air-conditioning indoor unit which concerns on one Embodiment. The block diagram which shows the control system of the air conditioning apparatus of FIG. The perspective view of the air-conditioning indoor unit which concerns on one Embodiment. The fragmentary sectional view of an air-conditioning indoor unit when the flap has closed the blower outlet. The fragmentary sectional view of an air-conditioning indoor unit when the flap has opened the blower outlet. The flowchart which shows the rotation speed switching control of the indoor fan of an air conditioning apparatus. The block diagram which shows the outline | summary of a structure of the air conditioning apparatus which concerns on a modification.

(1) Overall Configuration of Air Conditioner FIG. 1 shows a refrigerant piping system of an air conditioner to which an air conditioning indoor unit according to an embodiment of the present invention is applied. The air conditioner 1 is a distributed type air conditioner using a refrigerant piping system, and is an apparatus used for cooling and heating each room in a building by performing a vapor compression refrigeration cycle operation. The air conditioner 1 includes an air conditioner outdoor unit 2 as a heat source unit, a plurality of air conditioner indoor units 4 (in FIG. 1, two units of an air conditioner indoor unit 4a and an air conditioner indoor unit 4b), and an air conditioner outdoor unit. 1 and the 2nd refrigerant | coolant communication pipe | tube 7 as a refrigerant | coolant communication pipe | tube which connects 2 and the air-conditioning indoor unit 4 are provided. The main refrigerant circuit 10 of the air conditioner 1 is configured by connecting an air conditioning outdoor unit 2, an air conditioning indoor unit 4, and refrigerant communication pipes 6 and 7. The refrigerant is sealed in the main refrigerant circuit 10, and the refrigerant is compressed, cooled, depressurized, heated / evaporated, and compressed again as described later. It is like that. As the refrigerant, for example, one selected from R410A, R407C, R22, R134a, carbon dioxide, and the like is used.

(2) Detailed configuration of air conditioner (2-1) Air-conditioning indoor unit The air-conditioning indoor unit is installed by being embedded or suspended in the ceiling of a room such as a building, or by hanging on a wall surface of the room. Hereinafter, the air conditioning indoor unit 4 of the type embedded in the ceiling will be described. The air conditioning indoor unit 4 is connected to the air conditioning outdoor unit 2 via the refrigerant communication pipes 6 and 7 and constitutes a part of the main refrigerant circuit 10.

  Next, the configuration of the air conditioning indoor unit 4 will be described. In FIG. 1, two air conditioning indoor units 4a and 4b are shown as the air conditioning indoor unit 4. However, since each of the air conditioning indoor units 4 has almost the same configuration, only the configuration of the air conditioning indoor unit 4a is shown here. Will be explained. The difference between the air conditioning indoor units 4 a and 4 b is that the air conditioning indoor unit 4 b includes an indoor humidity sensor 49.

  The air conditioning indoor unit 4 a includes an indoor main refrigerant circuit 10 a that constitutes a part of the main refrigerant circuit 10. The indoor main refrigerant circuit 10a mainly includes an indoor expansion valve 41 that is a decompressor and an indoor heat exchanger 42 that is a use-side heat exchanger.

  The indoor expansion valve 41 is a mechanism for reducing the pressure of the refrigerant, and is an electric valve capable of adjusting the opening degree. The indoor expansion valve 41 has one end connected to the first refrigerant communication pipe 6 and the other end connected to the indoor heat exchanger 42.

  The indoor heat exchanger 42 is a cross fin type fin-and-tube heat exchanger composed of heat transfer tubes and a large number of fins, and functions as a refrigerant evaporator during cooling operation to cool indoor air. It is a heat exchanger that functions as a refrigerant condenser and heats indoor air during heating operation. The indoor heat exchanger 42 has one end connected to the indoor expansion valve 41 and the other end connected to the second refrigerant communication tube 7.

  The air conditioning indoor unit 4a includes an indoor fan 43 for sucking indoor air into the unit and supplying the indoor air again, and exchanges heat between the indoor air and the refrigerant flowing through the indoor heat exchanger 42. . The indoor fan 43 is a fan capable of changing the air volume of air supplied to the indoor heat exchanger 42, and is rotationally driven by an indoor fan motor 43a including a DC fan motor. In the indoor fan 43, for example, a centrifugal fan or a multi-blade fan is driven by the indoor fan motor 43a in order to send air to the indoor heat exchanger.

  The air conditioning indoor unit 4a is provided with various sensors. Specifically, an indoor liquid pipe temperature sensor 44 and an indoor gas pipe temperature sensor 45 each including a thermistor are provided, and the temperature of the refrigerant is measured from the temperature of the refrigerant pipe adjacent to the indoor heat exchanger 42. The indoor liquid pipe temperature sensor 44 detects the refrigerant temperature corresponding to the condensation temperature during the heating operation or the evaporation temperature during the cooling operation. Moreover, the indoor temperature sensor 46 is provided, This indoor temperature sensor 46 detects the temperature of the indoor air inhaled by the air-conditioning indoor unit 4 before heat exchange is performed. Furthermore, the air conditioning indoor unit 4a has an indoor control device 47 that controls the operation of each part constituting the air conditioning indoor unit 4a. The indoor control device 47 includes a microcomputer, a memory, and the like provided for controlling the air conditioning indoor unit 4a, and a remote controller (not shown) for individually operating the air conditioning indoor unit 4a. Exchange of control signals and the like, and exchange of control signals and the like with the outdoor control device 30 of the air conditioner outdoor unit 2 described later via the transmission line 8a.

(2-2) Air-conditioning outdoor unit The air-conditioning outdoor unit 2 is installed outside a building or the like, and is connected to the air-conditioning indoor units 4a and 4b via the first refrigerant communication pipe 6 and the second refrigerant communication pipe 7. Yes. The air conditioning outdoor unit 2 includes an outdoor main refrigerant circuit 10 c that constitutes a part of the main refrigerant circuit 10, and a supercooling refrigerant flow path 61 that branches from the main refrigerant circuit 10.

(2-2-1) Outdoor Main Refrigerant Circuit The outdoor main refrigerant circuit 10c mainly includes the compressor 21, the switching mechanism 22, the outdoor heat exchanger 23, the outdoor first expansion valve 25, and liquid gas heat. It has an exchanger 27, a liquid side closing valve 28 a, a gas side closing valve 28 b, and an accumulator 29. This outdoor main refrigerant circuit 10c mainly includes a compressor 21, a switching mechanism 22, an outdoor heat exchanger 23 as a heat source side heat exchanger, a receiver 24, and a second shut-off mechanism or a heat source side expansion mechanism. The outdoor first expansion valve 25, a liquid gas heat exchanger 27 as a temperature adjusting mechanism, a liquid side closing valve 28a as a first shut-off mechanism, and a gas side closing valve 28b are provided.

  The compressor 21 is a hermetic compressor driven by a compressor motor 21a. The rotation speed of the compressor motor 21a is controlled by, for example, an inverter, and the compressor 21 is configured to be able to vary the operating capacity.

  The switching mechanism 22 is a mechanism for switching the direction of the refrigerant flow. During the cooling operation, the outdoor heat exchanger 23 functions as a radiator for the refrigerant compressed by the compressor 21, and the indoor heat exchanger 42 functions as an evaporator for the refrigerant cooled in the outdoor heat exchanger 23. For this purpose, the switching mechanism 22 connects the refrigerant pipe on the discharge side of the compressor 21 and one end of the outdoor heat exchanger 23, and also connects the compressor suction side pipe 29a (including the accumulator 29) and the gas side closing valve 28b. (See the solid line of the switching mechanism 22 in FIG. 1). Further, the switching mechanism 22 causes the indoor heat exchanger 42 to function as a radiator for the refrigerant compressed by the compressor 21 during the heating operation, and the outdoor heat exchanger 23 is cooled by the indoor heat exchanger 42. To function as an evaporator. For this purpose, the switching mechanism 22 connects the refrigerant pipe on the discharge side of the compressor 21 and the gas side shut-off valve 28b, and connects the compressor suction side pipe 29a and one end of the outdoor heat exchanger 23 (FIG. 1 (see the broken line of the switching mechanism 22). The switching mechanism 22 is, for example, a four-way switching valve.

  The outdoor heat exchanger 23 is a cross fin type fin-and-tube heat exchanger composed of heat transfer tubes and a large number of fins, one end of which is connected to the switching mechanism 22 and the other end of the outdoor heat exchanger 23. The first expansion valve 25 is connected.

  The air conditioner outdoor unit 2 has an outdoor fan 26 for sucking outdoor air into the unit and discharging it to the outdoor again. The outdoor fan 26 exchanges heat between the outdoor air and the refrigerant flowing through the outdoor heat exchanger 23.

  The outdoor first expansion valve 25 is a mechanism for decompressing the refrigerant in the main refrigerant circuit 10, and is an electric valve capable of adjusting the opening degree. The outdoor first expansion valve 25 is configured to adjust the pressure, flow rate, and the like of the refrigerant flowing in the outdoor main refrigerant circuit 10c, so that the outdoor heat exchanger 23 in the refrigerant flow direction in the refrigerant circuit 10 when performing the cooling operation. It is also possible that the refrigerant is disposed downstream of the receiver 24 and upstream of the receiver 24 to block the passage of the refrigerant. One end of the outdoor first expansion valve 25 is connected to the outdoor heat exchanger 23, and the other end is connected to the liquid side shut-off valve 28 a via the liquid gas heat exchanger 27, and is connected to the liquid side of the outdoor heat exchanger 23. It is connected.

  The air-conditioning outdoor unit 2 has an outdoor fan 26 as a blower fan for sucking outdoor air into the unit and exchanging heat with the refrigerant in the outdoor heat exchanger 23 and then discharging it to the outside. The outdoor fan 26 is a fan capable of changing the air volume supplied to the outdoor heat exchanger 23, and is, for example, a propeller fan driven by a motor 26a composed of a DC fan motor or the like.

  The receiver 24 is connected between the outdoor first expansion valve 25 and the liquid-side closing valve 28a, and depends on the refrigerant circulation amount difference between the cooling operation and the heating operation, the fluctuation of the operation load of the air conditioning indoor unit 4, and the like. This is a container capable of storing surplus refrigerant generated in the refrigerant circuit 10.

  The liquid gas heat exchanger 27 is connected between the receiver 24 and the liquid side closing valve 28a. The liquid gas heat exchanger 27 is a pipe heat exchanger having a double-pipe structure in which a refrigerant pipe through which the refrigerant condensed in the heat source side heat exchanger flows and a branch pipe 64 described later are brought into contact with each other. The liquid gas heat exchanger 27 includes a refrigerant that flows through the main refrigerant circuit 10 from the outdoor heat exchanger 23 toward the air conditioning indoor unit 4, and a supercooling refrigerant flow path 61 from the outdoor second expansion valve 62 to the compressor suction side pipe. Heat exchange is performed with the refrigerant flowing to 29a. Thereby, the liquid gas heat exchanger 27 further cools the refrigerant condensed in the outdoor heat exchanger 23 during the cooling operation by this heat exchange, and increases the degree of supercooling of the refrigerant toward the air conditioning indoor unit 4.

  The accumulator 29 is disposed in a compressor suction side pipe 29 a between the switching mechanism 22 and the compressor 21.

(2-2-2) Supercooling Refrigerant Flow Channel The outdoor second expansion valve 62 is a mechanism for decompressing the refrigerant in the supercooling refrigerant flow channel 61 and is an electric valve capable of adjusting the opening degree. The outdoor second expansion valve 62 has one end connected to the liquid gas heat exchanger 27 and the other end connected to the supercooling refrigerant flow path 61. This subcooling refrigerant flow path 61 is constituted by a refrigerant pipe that goes from the outdoor second expansion valve 62 to the compressor suction side pipe 29 a between the switching mechanism 22 and the accumulator 29 through the liquid gas heat exchanger 27. Yes.

  The liquid gas heat exchanger 27 is provided with a branch pipe 64 as a cooling source. A portion of the refrigerant circuit 10 excluding the supercooling refrigerant flow path 61 is a main refrigerant circuit. The subcooling refrigerant flow path 61 is connected to the main refrigerant circuit so as to return the refrigerant branched between the liquid gas heat exchanger 27 and the receiver 24 to the suction side of the compressor 21. The refrigerant branched in the supercooling refrigerant passage 61 is decompressed and then introduced into the liquid gas heat exchanger 27. The refrigerant branched in the supercooling refrigerant flow path 61 is subjected to heat exchange with the refrigerant sent from the outdoor heat exchanger 23 to the indoor expansion valve 41 through the first refrigerant communication pipe 6, and then the suction side of the compressor 21. Returned to

  More specifically, the supercooling refrigerant flow path 61 includes a branch pipe 64, a junction pipe 65, and an outdoor second expansion valve 62. The branch pipe 64 is connected so that a part of the refrigerant sent from the outdoor first expansion valve 25 to the indoor expansion valve 41 is branched from a position between the outdoor heat exchanger 23 and the liquid gas heat exchanger 27. Yes. The junction pipe 65 is connected to the suction side of the compressor 21 so as to return to the suction side of the compressor 21 from the outlet on the supercooling refrigerant flow path side of the liquid gas heat exchanger 27. The outdoor second expansion valve 62 is an electric expansion valve, and functions as a communication pipe expansion mechanism for adjusting the flow rate of the refrigerant flowing through the supercooling refrigerant flow path 61. Thereby, the refrigerant sent from the outdoor heat exchanger 23 to the indoor expansion valve 41 is caused by the refrigerant flowing in the subcooling refrigerant flow path 61 after being depressurized by the outdoor second expansion valve 62 in the liquid gas heat exchanger 27. To be cooled. That is, the capacity control of the liquid gas heat exchanger 27 is performed by adjusting the opening degree of the outdoor second expansion valve 62.

  Further, as described later, the supercooling refrigerant channel 61 connects a portion of the refrigerant circuit 10 between the liquid side closing valve 28a and the outdoor first expansion valve 25 and a suction side portion of the compressor 21. It is designed to function as a communication pipe.

  The liquid side shutoff valve 28a and the gas side shutoff valve 28b are valves provided at connection ports with external devices and pipes (specifically, the first refrigerant communication pipe 6 and the second refrigerant communication pipe 7). The liquid side shut-off valve 28a is connected to the liquid gas heat exchanger 27, and the gas side shut-off valve 28b is connected to the switching mechanism 22, thereby blocking the passage of the refrigerant.

(2-2-3) Outdoor Control Device and Various Sensors The air-conditioning outdoor unit 2 has an outdoor control device 30 that controls the operation of each part constituting the air-conditioning outdoor unit 2. The outdoor control device 30 includes a microcomputer provided for controlling the air conditioning outdoor unit 2, a memory, an inverter circuit for controlling the motor 26a, and the like, and the indoor control devices for the air conditioning indoor units 4a and 4b. Control signals and the like can be exchanged with the terminal 47 via the transmission line 8a. That is, the indoor control device 47, the outdoor control device 30, and the transmission line 8a connecting the indoor control devices 47 constitute the air conditioning control device 8 that controls the operation of the entire air conditioner 1.

  The air conditioner outdoor unit 2 is provided with various sensors. The refrigerant pipe on the discharge side of the compressor 21 is provided with a discharge pressure sensor 31 that detects the compressor discharge pressure and a discharge temperature sensor 32 that detects the compressor discharge temperature. The compressor suction side pipe 29a is provided with a suction temperature sensor 34 for detecting the temperature of the gas refrigerant sucked into the compressor 21 and a suction pressure sensor 33 for detecting the compressor suction pressure. A liquid pipe temperature sensor 35 for detecting the temperature of the refrigerant (that is, the liquid pipe temperature) is provided at the outlet of the liquid gas heat exchanger 27 on the main refrigerant circuit side. An outdoor temperature sensor 36 for detecting the temperature of the outdoor air flowing into the inside (that is, the outdoor temperature) is provided on the outdoor air suction side of the air conditioning outdoor unit 2. From the liquid gas heat exchanger 27 to the low-pressure refrigerant pipe between the switching mechanism 22 and the accumulator 29, a supercooling refrigerant flow of the liquid gas heat exchanger 27 flows into the merge pipe 65 of the supercooling refrigerant flow path 61. A bypass temperature sensor 63 for detecting the temperature of the refrigerant flowing through the roadside outlet is provided. The discharge temperature sensor 32, the suction temperature sensor 34, the liquid pipe temperature sensor 35, the outdoor temperature sensor 36, and the bypass temperature sensor 63 are composed of thermistors.

(2-3) Refrigerant communication pipes The refrigerant communication pipes 6 and 7 are refrigerant pipes constructed on site when the air-conditioning outdoor unit 2 and the air-conditioning indoor unit 4 are installed at the installation location. The first refrigerant communication pipe 6 is connected to the air-conditioning outdoor unit 2 and the air-conditioning indoor units 4a and 4b. During the cooling operation, the liquid refrigerant whose degree of supercooling in the liquid gas heat exchanger 27 is increased to the indoor expansion valve 41. And a refrigerant pipe that sends the liquid refrigerant condensed in the indoor heat exchanger 42 to the outdoor heat exchanger 23 of the air conditioning outdoor unit 2 during heating operation. The second refrigerant communication pipe 7 is connected to the air-conditioning outdoor unit 2 and the air-conditioning indoor units 4a and 4b, and sends the gas refrigerant evaporated in the indoor heat exchanger 42 to the compressor 21 of the air-conditioning outdoor unit 2 during the cooling operation. In the heating operation, the refrigerant pipes send the gas refrigerant compressed in the compressor 21 to the indoor heat exchangers 42 of the air conditioning indoor units 4a and 4b.

(2-4) Air Conditioning Control Device FIG. 2 shows a control block diagram of the air conditioner 1. The air conditioning control device 8 as a control means for performing various operation controls of the air conditioner 1 is configured by an outdoor control device 30 and an indoor control device 47 connected via a transmission line 8a as shown in FIG. The air conditioning control device 8 receives the detection signals of the various sensors 31 to 36, 44 to 46, 63, and controls the various devices 21, 22, 25, 26, 41, 43, 62 based on these detection signals and the like.

(3) Operation of Air Conditioner Next, the basic operation of the air conditioner 1 according to the present embodiment will be described. Note that control in various operations described below is performed by the air conditioning control device 8.

(3-1) Cooling Operation During the cooling operation, the switching mechanism 22 is in the state indicated by the solid line in FIG. 1, that is, the discharge side of the compressor 21 is connected to the gas side of the outdoor heat exchanger 23, and the compressor 21 Is in a state of being connected to the gas side of the indoor heat exchanger 42 via the gas side closing valve 28 b and the second refrigerant communication pipe 7. During the cooling operation, the outdoor first expansion valve 25 is fully opened, and the liquid side closing valve 28a and the gas side closing valve 28b are opened. The opening degree of each indoor expansion valve 41 is adjusted so that the superheat degree of the refrigerant at the outlet of the indoor heat exchanger 42 (that is, the gas side of the indoor heat exchanger 42) becomes constant at the superheat degree target value. ing. The superheat degree of the refrigerant at the outlet of each indoor heat exchanger 42 is obtained by subtracting the refrigerant temperature value (corresponding to the evaporation temperature) detected by the indoor liquid pipe temperature sensor 44 from the refrigerant temperature value detected by the indoor gas pipe temperature sensor 45. From the refrigerant temperature value detected by the indoor gas pipe temperature sensor 45, the suction pressure of the compressor 21 detected by the suction pressure sensor 33 is converted into a saturation temperature value corresponding to the evaporation temperature. It is detected by subtracting the saturation temperature value of this refrigerant.

  The opening degree of the outdoor second expansion valve 62 is adjusted so that the superheat degree of the refrigerant at the outlet of the liquid gas heat exchanger 27 on the supercooling refrigerant channel side becomes the superheat degree target value (hereinafter, superheat degree control). Called). The degree of superheat of the refrigerant at the outlet of the liquid gas heat exchanger 27 on the side of the supercooling refrigerant flow path is converted to a saturation temperature value corresponding to the evaporation temperature by converting the suction pressure of the compressor 21 detected by the suction pressure sensor 33. This is detected by subtracting the saturation temperature value of the refrigerant from the refrigerant temperature value detected by the temperature sensor 63.

  When the compressor 21, the outdoor fan 26, and the indoor fan 43 are operated in the state of the refrigerant circuit 10, the low-pressure gas refrigerant is sucked into the compressor 21 and compressed to become high-pressure gas refrigerant. Thereafter, the high-pressure gas refrigerant is sent to the outdoor heat exchanger 23 via the switching mechanism 22, exchanges heat with the outdoor air supplied by the outdoor fan 26, and is condensed to become a high-pressure liquid refrigerant. The high-pressure liquid refrigerant passes through the outdoor first expansion valve 25 and is temporarily stored in the receiver 24, and then flows into the liquid gas heat exchanger 27 and flows through the subcooling refrigerant flow path 61. The refrigerant is further cooled by exchanging heat with the refrigerant to be in a supercooled state. At this time, a part of the high-pressure liquid refrigerant condensed in the outdoor heat exchanger 23 is branched into the subcooling refrigerant flow path 61, and after being decompressed by the outdoor second expansion valve 62, the refrigerant enters the suction side of the compressor 21. Returned. Here, a part of the refrigerant passing through the outdoor second expansion valve 62 is evaporated by being depressurized to near the suction pressure of the compressor 21. Then, the refrigerant flowing from the outlet of the outdoor second expansion valve 62 of the supercooling refrigerant flow path 61 toward the suction side of the compressor 21 passes through the liquid gas heat exchanger 27 and the outdoor heat on the main refrigerant circuit side. Heat exchange is performed with the high-pressure liquid refrigerant sent from the exchanger 23 to the air conditioning indoor unit 4.

  The supercooled high-pressure liquid refrigerant is sent to the air conditioning indoor unit 4 via the liquid side closing valve 28 a and the first refrigerant communication pipe 6.

  The high-pressure liquid refrigerant sent to the air-conditioning indoor unit 4 is decompressed to near the suction pressure of the compressor 21 by the indoor expansion valve 41 to become a low-pressure gas-liquid two-phase refrigerant and sent to the indoor heat exchanger 42. In the indoor heat exchanger 42, heat is exchanged with the room air to evaporate to become a low-pressure gas refrigerant.

  This low-pressure gas refrigerant is sent to the air-conditioning outdoor unit 2 via the second refrigerant communication pipe 7, and is again sucked into the compressor 21 via the gas-side closing valve 28 b and the switching mechanism 22. As described above, the air conditioner 1 uses the outdoor heat exchanger 23 as a condenser for the refrigerant compressed in the compressor 21 and the indoor heat exchanger 42 after being condensed in the outdoor heat exchanger 23, the receiver 24, A cooling operation is performed so as to function as an evaporator of the refrigerant sent through the first refrigerant communication pipe 6 and the indoor expansion valve 41.

(3-2) Heating Operation During the heating operation, the switching mechanism 22 is in the state indicated by the broken line in FIG. 1, that is, the discharge side of the compressor 21 is heated in the room via the gas-side stop valve 28 b and the second refrigerant communication pipe 7. It is connected to the gas side of the exchanger 42 and the suction side of the compressor 21 is connected to the gas side of the outdoor heat exchanger 23. The opening degree of the outdoor first expansion valve 25 is adjusted in order to reduce the refrigerant flowing into the outdoor heat exchanger 23 to a pressure at which the refrigerant can be evaporated in the outdoor heat exchanger 23 (that is, evaporation pressure). ing. Moreover, the liquid side closing valve 28a and the gas side closing valve 28b are opened. The opening of the indoor expansion valve 41 is adjusted so that the degree of supercooling of the refrigerant at the outlet of the indoor heat exchanger 42 is constant at the target value of the degree of supercooling. The degree of supercooling of the refrigerant at the outlet of the indoor heat exchanger 42 is calculated by converting the discharge pressure of the compressor 21 detected by the discharge pressure sensor 31 into a saturation temperature value corresponding to the condensation temperature. This is detected by subtracting the refrigerant temperature value detected by the liquid pipe temperature sensor 44.

  When the compressor 21, the outdoor fan 26, and the indoor fan 43 are operated in the state of the refrigerant circuit 10, the low-pressure gas refrigerant is sucked into the compressor 21 and compressed to become a high-pressure gas refrigerant. The air is sent to the air conditioning indoor unit 4 via the side closing valve 28 b and the second refrigerant communication pipe 7.

  The high-pressure gas refrigerant sent to the air-conditioning indoor unit 4 exchanges heat with indoor air in the indoor heat exchanger 42 to condense into high-pressure liquid refrigerant, and then passes through the indoor expansion valve 41. At this time, the pressure is reduced according to the opening degree of the indoor expansion valve 41.

  The refrigerant that has passed through the indoor expansion valve 41 is sent to the air-conditioning outdoor unit 2 via the first refrigerant communication pipe 6, and the liquid side closing valve 28 a, the liquid gas heat exchanger 27, the receiver 24, and the outdoor first expansion valve. After being further depressurized via 25, it flows into the outdoor heat exchanger 23. The low-pressure gas-liquid two-phase refrigerant flowing into the outdoor heat exchanger 23 exchanges heat with outdoor air supplied by the outdoor fan 26 to evaporate into a low-pressure gas refrigerant, and passes through the switching mechanism 22. Then, it is sucked into the compressor 21 again.

  Operation control in the normal operation mode as described above is performed by the air conditioning control device 8 (the indoor control device 47 and the outdoor control device 30 and the transmission line 8a connecting them) that performs normal operation including cooling operation and heating operation. Is called.

(4) Air Conditioning Indoor Unit FIG. 3 is a perspective view of the air conditioning indoor unit. In FIG. 3, the air conditioning indoor unit 4 includes a casing 51 and a lower panel 52. The casing 51 is a substantially octagonal box-like body in which the long side and the short side are alternately formed in a plan view, and the above-described equipment such as the indoor heat exchanger 42 and the indoor fan 43 capable of controlling the air volume is contained inside the casing 51. And is attached to the ceiling of the space to be air-conditioned.

(4-1) Bottom Panel The bottom panel 52 is a plate-like body having a substantially quadrangular shape in plan view, and is fitted into the ceiling opening into which the casing 51 is inserted. The lower surface panel 52 has a suction port 53 for sucking air and four blowout ports 54 formed so as to surround the suction port 53.

  The suction port 53 is a substantially quadrangular opening. The suction port 53 is provided with a suction grill 55 and a filter (not shown) for removing dust in the air sucked from the suction port 53. Moreover, the indoor humidity sensor 49 is arrange | positioned at the suction inlet 53 (between the suction grill 55 and a filter), and detects the humidity of the air-conditioning object space.

  The air outlet 54 is formed along each side of the quadrangle of the lower surface panel 52. Each of the four outlets 54 is provided with a flap 56.

(4-2) Flap The flap 56 is a plate-like member that is elongated along the longitudinal direction of the air outlet 54, and both end portions in the longitudinal direction are rotatable around the longitudinal axis. It is supported by the lower panel 52. Further, the flap 56 can change the blowing direction of the conditioned air by changing the posture.

  FIG. 4 is a partial cross-sectional view of the air conditioning indoor unit when the flap closes the outlet. FIG. 5 is a partial cross-sectional view of the air-conditioning indoor unit when the flap is in a posture that makes the blowing direction of the conditioned air most horizontal. In FIG. 4, the flap 56 is rotated by a predetermined angle from the position where the flap 56 closes the outlet 54 in the direction to open the outlet 54 and stops. Although this posture of the flap 56 is not a horizontal posture, since the flap 56 is a curved plate-like member, the conditioned air flows along the curved surface of the flap 56 and is deflected in a substantially horizontal direction when leaving the flap 56. The air conditioner indoor unit 4 can further gradually increase the angle of rotation about the rotation shaft 56a, thereby changing the blowing direction to a direction close to the vertically downward direction. can go.

(4-3) Control of fan air volume during cooling operation Control of the fan air volume during the cooling operation of the air conditioning indoor unit 4 will be described below. In particular, when the operation is performed with the difference between the high and low pressures of the refrigeration cycle being reduced in order to reduce the power consumption, the compressor power is reduced, so the influence of the power consumption of the indoor fan 43 on the coefficient of performance (COP) of the air conditioner 1 is relatively. Become bigger. Therefore, when the air-conditioning indoor unit 4 is operated with a low load and a low differential pressure, a demand for suppressing the power consumption of the indoor fan 43 increases. The high-low pressure difference is obtained, for example, by subtracting the suction side pressure of the compressor 21 (detection value LP of the suction pressure sensor 33) from the discharge side pressure of the compressor 21 (detection value HP of the discharge pressure sensor 31).

  However, if the rotational speed of the indoor fan 43 is reduced unnecessarily, condensation may occur. For this reason, the number of rotations that can sufficiently suppress the occurrence of condensation is determined from data accumulated in the past, and the lower limit value of the air volume control range is, for example, in the range of 60 to 70% of the rotation speed that gives the maximum air volume. Set to one of the values. Since the air flow control range lower limit value is a rotational speed that can prevent the occurrence of condensation regardless of the indoor environment, it is generally determined with a margin.

  Therefore, the indoor control device 47 determines whether or not the indoor environment is an environment in which condensation does not easily occur, and switches the lower limit value of the fan air volume. Thereby, for example, the lower limit value of the fan air volume set by the remote controller is changed in the indoor control device 47 to expand the range of the air volume that can be set by the user. FIG. 6 is a flowchart for explaining the switching operation of the lower limit value of the air volume control range in the indoor control device 47.

  First, the indoor control device 47 determines whether or not the cooling operation is performed (step S1). When the cooling operation is started, the indoor control device 47 determines whether or not a predetermined time has elapsed by a timer (not shown) built in the indoor control device 47 (step S2). Since the indoor environment changes with time, for example, immediately after the start of the cooling operation, it is determined whether a preset predetermined time has passed, such as 10 minutes, 20 minutes, and so on.

  As the predetermined time elapses, the indoor control device 47 detects the evaporation temperature in the indoor heat exchanger 42 using the indoor liquid pipe temperature sensor 44 and also detects the indoor temperature using the indoor temperature sensor 46 (step S3). . Then, the dew point temperature is calculated from the detected room temperature (step S4). For example, although there is a difference depending on the region, since Japan is a region with relatively high humidity, the dew point temperature is calculated with the relative humidity set to 80%. When such a calculation is performed, the dew point temperature is usually estimated to be higher than the actual one, but a high estimate is preferable from the viewpoint of suppressing dew condensation. Also, the relative humidity setting may be switched between winter and summer. When installing in Japan, the relative humidity in winter will be lower, so the relative humidity setting in winter should be set lower than in summer. You can also.

  From past experiments and the like, it has been confirmed that condensation does not occur if a temperature several degrees (α degrees) higher than the evaporation temperature is higher than the dew point temperature. Therefore, the indoor control device 47 determines whether or not (evaporation temperature Te + α)> indoor dew point temperature (step S5). The constant α used at this time is set in advance for each model in consideration of the place or area where the air conditioning indoor unit 4 is installed. Alternatively, the constant α may be set when the air conditioning indoor unit 4 is attached or after it is attached.

  When (evaporation temperature Te + α)> indoor dew point temperature, the indoor control device 47 switches to a mode in which the preset lower limit value of the rotational speed of the indoor fan 43 is low (step S6). For example, in general, the air conditioning indoor unit 4 is switched so that the lower limit is set to 70% of the rotational speed that gives the maximum air volume, and the lower limit is set to 40% of the rotational speed that gives the maximum air volume. Thereby, it is possible to set a lower air volume than the normal mode for the indoor control device 47 from the remote controller. On the other hand, when (evaporation temperature Te + α) ≦ the indoor dew point temperature, the indoor control device 47 maintains the normal mode without switching to the mode in which the lower limit value of the rotational speed of the indoor fan 43 is low (step S7). ).

  In the next step S8, the indoor control device 47 determines whether or not to continue the determination as to whether or not to change the rotational speed. For example, when it is no longer necessary to continue to determine whether or not to change the rotational speed, such as when there is an instruction to stop operation, the routine for determining whether or not to change the rotational speed is terminated.

(5) Features of the Air Conditioner In the air conditioning indoor unit 4 according to this embodiment, when the indoor air is cooled by heat exchange by the indoor heat exchanger 42, the indoor fan 43 blows indoor air to the indoor heat exchanger 42. To do. The indoor control device 47 (control device) controls the indoor fan 43 and determines whether or not to change the lower limit value of the rotational speed of the indoor fan 43 based on at least the evaporation temperature Te of the indoor heat exchanger 42.

  In the present embodiment, the determination based on the evaporation temperature Te in the indoor control device 47 employs a criterion for determining whether or not the evaporation temperature Te + α is higher than the dew point temperature in step S5 of the flow shown in FIG. Yes. Therefore, the indoor control device 47 calculates the dew point temperature based on the detection result of the indoor temperature sensor 46 (indoor temperature detector). By calculating the dew point temperature in this way, a sensor for measuring the dew point temperature can be omitted, and it can be configured at low cost.

  The setting that the evaporation temperature Te + α is higher than the dew point temperature satisfies the condition that the condensation temperature is not caused by the indoor air after heat exchange, which has been confirmed by experiments and simulations. The constant α at this time is determined in advance by experiments or simulations. Therefore, the rotation speed of the indoor fan can be reduced without impairing the function of preventing condensation.

  For example, when the air conditioner 1 is operating at a load factor of 15% when the outside air temperature is 20 ° C., the rotational speed of the indoor fan 43 is set to 70% of the rotational speed that gives the maximum air volume. It has been confirmed that the COP of the system is improved by 9% when the rotational speed of the indoor fan 43 is set to 30%.

(6) Modification (6-1) Modification A
In the air conditioning indoor unit 4 according to the above-described embodiment, a case has been described in which it is determined whether or not the lower limit value of the rotation speed of the indoor fan 43 is changed only by the indoor control device 47 as the control device of the present invention. However, the control device that determines whether or not to change the lower limit value of the rotation speed of the indoor fan 43 need not be incorporated in the air conditioning indoor unit 4. For example, the outdoor control device 30 that transmits and receives data to and from the indoor control device 47 of the air conditioning indoor unit 4 can be configured to perform the determination in step S5 of FIG. In such a case, the outdoor control device 30 can be regarded as a control device for the air conditioning indoor unit 4. Similarly, the indoor control device 47 and the outdoor control device 30 may make a determination in cooperation. In this case, the air conditioning control device 8 can be regarded as a control device for the air conditioning indoor unit 4.

(6-2) Modification B
In the above embodiment, the dew point temperature is calculated based on the detection result of the indoor temperature sensor 46. However, when the indoor humidity sensor 49 (indoor humidity detector) is provided as in the air conditioning indoor unit 4b, the indoor control is performed. The apparatus 47 can be configured to calculate the dew point temperature in consideration of the detection result of the indoor temperature detector. By calculating the dew point temperature using the detection result of the indoor humidity sensor 49 in addition to the detection result of the indoor temperature sensor 46, the dew point temperature is more accurately calculated than calculating the dew point temperature using only the detection result of the indoor temperature sensor 46. Can be calculated.

  By calculating the dew point temperature using the indoor temperature sensor 46 and the indoor humidity sensor 49, the number of times it can be determined that the lower limit value of the rotational speed of the indoor fan 43 can be lowered while preventing the occurrence of condensation is increased. Thereby, since the opportunity to drive the indoor fan 43 at a low rotation speed increases, the opportunity to reduce power consumption can be increased.

  Instead of calculating the dew point temperature in the indoor control device 47, a sensor that directly measures the dew point temperature may be attached to the air conditioning indoor unit 4, and the indoor control device 47 rotates based on the dew point temperature directly measured by the sensor. It can also be determined whether or not to change the lower limit of the number. In such a case, the same effect as in the above case can be obtained.

(6-3) Modification C
In the above embodiment, the case has been described where, in step S5 illustrated in FIG. 6, the determination as to whether or not the lower limit value is decreased by a predetermined value is performed only once. However, the lower limit value can be reduced stepwise.

  For example, the constants α1 and α2 are set, α1> α2, for example, α1 = ° C., α2 = 2 ° C., the lower limit value without change is r0, and the lower limit value that has been reduced by one step is r1, and the lower step value is decreased by two steps. The lower limit is set to r2, that is, r0> r1> r2, for example, r0 = 60%, r1 = 45%, r2 = 30%. The indoor control device 47 changes the lower limit value of the rotational speed to r1 when the evaporation temperature Te + α1> dew point temperature ≧ evaporation temperature Te + α2, and changes the lower limit value of the rotational speed to r2 when the evaporation temperature Te + α2> dew point temperature. When evaporating temperature Te + α1 ≦ dew point temperature, the lower limit value r0 is kept unchanged.

(6-4) Modification D
In the above embodiment, the case where the air conditioner 1 is configured by the air conditioner outdoor unit 2 and the air conditioner indoor unit 4 has been described. However, as shown in FIG. The present invention can also be applied to the apparatus 1A.

  The air conditioner 1A of FIG. 7 includes an external air conditioner 80 having a humidity adjustment function and a ventilation function, an air conditioner 90 having a temperature adjustment function, and a system control device 95 that controls the external air conditioner 80 and the air conditioner 90. It can be said that. The air conditioner 90 is configured by the air conditioner outdoor unit 2 and the air conditioner indoor unit 4 described above. As shown in FIG. 7, the external air conditioner 80 having a humidity adjusting function is provided with a humidity detector 81 and a temperature detector 82, and the humidity of the air blown indoors through the external air conditioner 80. Or temperature is detected. Humidity and temperature data detected by the external air conditioner 80 can be transmitted from the external air conditioner control device 83 of the external air conditioner 80 to the indoor control device 47 of the air conditioning indoor unit 4 via the system control device 95. In such a case, the indoor control device 47 can calculate the indoor dew point temperature based on the data transmitted from the external air conditioner 80. In this way, the indoor controller 47 calculates the indoor dew point temperature by using the detection result of the indoor temperature sensor 46 of the air conditioning indoor unit 4 and the data of the humidity detector 81 of the external air conditioner 80 to calculate the dew point temperature. And a method of calculating the dew point temperature using data of the humidity detector 81 and the temperature detector 82 of the external air conditioner 80. Any method may be used. For example, at the start of operation of the air conditioning indoor unit 4, the dew point temperature is calculated using the data of the humidity detector 81 and the temperature detector 82 of the external air conditioner 80, and a predetermined time elapses after the operation of the air conditioning indoor unit 4 starts. The dew point temperature is calculated by using the detection result of the indoor temperature sensor 46 of the air conditioning indoor unit 4 and the data of the humidity detector 81 of the external air conditioner 80 so that the respective methods are switched according to time, place and situation. It may be.

(6-5) Modification E
In the above-described embodiment, the case where the air conditioning indoor unit 4 is a ceiling embedded type has been described. However, the air conditioning indoor unit 4 may be of a type other than the ceiling embedded type. The invention can be applied.

DESCRIPTION OF SYMBOLS 1,1A Air conditioning apparatus 2 Air-conditioning outdoor unit 8 Air-conditioning control apparatus 4 Air-conditioning indoor unit 30 Outdoor control apparatus 42 Indoor heat exchanger 43 Indoor fan 46 Indoor temperature sensor 47 Indoor control apparatus 49 Indoor humidity sensor 80 External air conditioner

JP 2003-106619 A

Claims (4)

An indoor heat exchanger (42) for cooling indoor air by heat exchange;
An indoor fan (43) for blowing indoor air to the indoor heat exchanger;
A control device (8, 30, 47) for controlling the indoor fan and determining whether or not to change the lower limit value of the rotational speed of the indoor fan based on at least the evaporation temperature of the indoor heat exchanger; Air conditioning indoor unit. A casing (51) for housing the indoor heat exchanger and the indoor fan;
An indoor temperature detector (46) for detecting the temperature of the indoor air around the casing;
The controller is
The indoor dew point temperature is calculated based on the temperature of the indoor air around the casing, and whether or not the lower limit value of the rotation speed of the indoor fan is changed is determined based on the indoor dew point temperature and the evaporation temperature of the indoor heat exchanger. To judge based on,
The air conditioning indoor unit according to claim 1. An indoor humidity detector (49) for detecting the humidity of the indoor air around the casing;
The controller is
The indoor dew point temperature is calculated based on the temperature and humidity of the indoor air around the casing, and whether or not the lower limit value of the rotation speed of the indoor fan is changed is determined based on the indoor dew point temperature and the indoor heat exchanger. Judgment based on the evaporation temperature of
The air conditioning indoor unit according to claim 2. The air conditioning indoor unit is connected to an external air conditioner (80),
The control device predicts the indoor dew point temperature based on data given from the external air conditioner,
The air conditioning indoor unit according to any one of claims 1 to 3.

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