JPWO2018167961A1 - Air conditioner - Google Patents

Abstract

An air conditioner is an outdoor unit including a refrigerant circuit in which a compressor, an outdoor heat exchanger, a plurality of expansion units, and a plurality of indoor heat exchangers are connected by piping and a refrigerant flows, and at least a compressor and an outdoor heat exchanger. And a mode for controlling the operation of the plurality of indoor units that respectively accommodate at least the plurality of indoor heat exchangers and the plurality of expansion units, based on the degree of superheat of the outlet side of the plurality of indoor heat exchangers during the cooling operation. And a control unit having a superheat control mode for controlling the expansion unit, and a supercooling control mode for controlling all the expansion units based on the degree of subcooling of the outdoor heat exchanger during the cooling operation. If it is determined that there is an indoor unit unsuitable for the overheat control mode by the judging means for judging whether or not there is an indoor unit unsuitable for the overheat control mode among the plurality of indoor units, the overheat control mode is determined. Control mode Having a switching means for switching the subcooling control mode from.

Description

  The present invention relates to an air conditioner provided with a plurality of indoor units.

  Conventionally, a multi-type air conditioner provided with a plurality of indoor units is known. The multi-type air conditioner includes an outdoor unit and an indoor unit connected to the outdoor unit by extension piping. The outdoor unit includes a compressor, a four-way valve that switches the refrigerant flow direction, an outdoor heat exchanger, an outdoor fan, a valve for liquid side extension piping connection, a valve for gas side extension piping connection, and a discharge on the high pressure side of the compressor. A pressure sensor disposed in the side pipe, an outdoor outlet side temperature sensor for detecting the temperature of the refrigerant flowing to the outlet side of the outdoor heat exchanger during the cooling operation, and an outdoor control device are provided. The indoor unit includes a plurality of electronic expansion valves for decompressing the condensed refrigerant, a plurality of indoor heat exchangers, a plurality of indoor fans, and an indoor inlet for detecting the temperature of the refrigerant flowing to the inlet side of the indoor heat exchanger during cooling operation. A side temperature sensor, an indoor outlet temperature sensor for detecting the temperature of the refrigerant flowing to the outlet side of the indoor heat exchanger during the cooling operation, and an indoor control device are provided. A refrigerant circuit is configured by connecting a compressor, a four-way valve, an outdoor heat exchanger, an electronic expansion valve, and an indoor heat exchanger by piping. The outdoor control device and the indoor control device operate the electronic expansion valve based on the pressure detected by the pressure sensor, the outdoor outlet temperature sensor, the indoor inlet temperature sensor, and the indoor outlet temperature sensor. Control.

  Further, the indoor control device stores an indoor unit form or a capability band, which is information unique to each indoor unit, and the indoor control device uses information such as the indoor unit form or the capability band, using various communication means. And transmit to the outdoor control device. Thereby, the indoor unit and the outdoor unit can share information such as the indoor unit configuration or the capacity band. Further, in the refrigerant circuit, during the cooling operation, the four-way valve is switched to connect the discharge side piping of the compressor and the outdoor heat exchanger, the outdoor heat exchanger acts as a condenser, and the indoor heat exchange is performed. Acts as an evaporator. During the cooling operation, the electronic expansion valve in each indoor unit overheats the evaporator derived from the difference between the indoor evaporation temperature detected by the indoor inlet temperature sensor and the indoor outlet temperature detected by the indoor outlet temperature sensor. The degree of opening is controlled such that the degree SH_e [deg] approaches the target degree of superheat SHm_e [deg]. In general, SH_e increases as the opening degree of the electronic expansion valve decreases, and decreases as the opening degree of the electronic expansion valve increases.

  In the multi-type air conditioner, a plurality of indoor units are connected. And there may be a gap between the room temperature and the set temperature where the indoor units are installed. In the case of a room where the room temperature and the set temperature are almost equal, the cooling capacity may be small. On the other hand, in the case of a room where there is a gap between the room temperature and the set temperature, it is necessary to increase the cooling capacity. That is, in the case of a room where the room temperature and the set temperature are almost equal, the value of SHm_e is increased, and the amount of refrigerant flowing is suppressed by throttling the opening degree of the electronic expansion valve to suppress the cooling capacity. desired. In addition to controlling the opening degree of the electronic expansion valve using such superheat degree of the evaporator, it is also known to control the opening degree of the electronic expansion valve using the subcooling degree of the condenser. The electronic expansion valve in each indoor unit has the degree of supercooling SC_hex of the condenser derived from the difference between the high pressure side saturation temperature for which the high pressure detected by the pressure sensor is required and the temperature detected by the outdoor outlet side temperature sensor. The degree of opening is controlled so that [deg] approaches the target degree of supercooling SCm_hex [deg], and is distributed according to the capacity zone of each indoor unit.

  When the electronic expansion valve of each indoor unit during cooling operation is controlled using the degree of subcooling of the condenser, there is no individual control target value in each indoor unit. For this reason, in the case of a room where the room temperature and the set temperature are substantially equal, it is difficult to control the room by increasing the value of SHm_e. In addition, the outlet of the indoor heat exchanger may be moist, and the required amount of refrigerant increases, the dryness of the refrigerant sucked into the compressor decreases, and the low pressure loss increases, and the liquid back to the compressor There are concerns such as Therefore, in the multi-type air conditioner, control of the electronic expansion valve using the degree of superheat of the evaporator is often employed.

  Here, when SH_e becomes excessive during the cooling operation, there is a possibility that a part of the indoor heat exchanger becomes dry. When a part of the indoor heat exchanger becomes dry, the air passing through the dry part is not cooled and becomes a wind with high temperature and high humidity. On the other hand, the air which has passed through the non-dry part is cooled and becomes a low temperature and low humidity wind. When the high temperature and high humidity wind and the low temperature and low humidity wind are mixed, the high temperature and high humidity air is cooled, and when it reaches the dew point temperature, it becomes dew and accumulates in the air passage. As a result, there is a risk that a dew skipping phenomenon may occur in which the accumulated dew flies out of the outlet of the indoor unit by the wind passing through the air path.

  Due to various circumstances such as productivity, the indoor outlet side temperature sensor may be attached at a position slightly closer to the middle between the inlet and the outlet of the indoor heat exchanger. In this case, SH_e is derived when SH_e is derived based on the temperature detected by the indoor inlet side temperature sensor and the temperature detected by the indoor outlet side temperature sensor to control the opening degree of the electronic expansion valve. However, the value is smaller than the actual degree of superheat. That is, at the degree of superheat, wrinkles occur between the detected value and the actual value. If control of the opening degree of the electronic expansion valve of each indoor unit is continued in order to bring SH_e close to the target degree of superheat SHm while wrinkling occurs, the actual degree of superheat becomes larger than the target degree of superheat, It becomes easy for the phenomenon of the dew jump etc. by dry condition to occur.

  The optimum value of the degree of superheat on the indoor unit outlet side is about 1 to 5 [deg], and the target degree of superheat SHm_e is generally set to about 2 to 4 [deg]. In order to avoid the dry state, if the indoor outlet side temperature sensor is attached at a position slightly closer to the middle between the inlet and the outlet of the indoor heat exchanger, the value of the target superheat degree SHm_e of the indoor unit It is necessary to make it smaller intentionally, but it is not easy to grasp how small it will be. In addition, the indoor outlet side temperature sensor may be attached at a position where the degree of superheat can not be detected at all. In this case, a simple specification change such as changing the target degree of superheat can not be used. In this case, it is necessary to change the installation position of the indoor outlet side temperature sensor to a position where the degree of superheat can be appropriately detected. That is, it involves a change in hardware specifications.

  Here, Patent Document 1 discloses an air conditioner that stores in advance the target degree of superheat of the evaporator according to the type of indoor unit connected to the outdoor unit. Patent document 1 performs optimal control individually for every indoor unit by this.

JP 2001-263760 A

  However, Patent Document 1 does not disclose at which position of the indoor heat exchanger the indoor outlet side temperature sensor is provided. In Patent Document 1, SH_e is derived based on the temperature detected by the indoor inlet side temperature sensor and the temperature detected by the indoor outlet side temperature sensor, and the degree of opening of the electronic expansion valve so that SH_e approaches SHm_e Is controlled. Here, when the indoor outlet side temperature sensor is attached between the inlet and the outlet of the indoor heat exchanger, the derived SH_e has a value smaller than the actual degree of superheat. At this time, the indoor heat exchanger is in a dry state, and there is a possibility that the dew scattering phenomenon may occur. In addition, the heat exchange performance may be degraded due to the deterioration of the refrigerant distribution rate inside the indoor heat exchanger.

  In order to avoid this, it is conceivable to change the control of the electronic expansion valve corresponding to each indoor unit to control using the degree of subcooling of the condenser. The control of the electronic expansion valve using the degree of subcooling of the condenser is based on the degree of opening of the electronic expansion valve of each indoor unit such that the degree of subcooling SC_hex [deg] of the condenser approaches the target degree of subcooling SCm_hex [deg]. It is control which determines the total value of and distributes according to the capability etc. of each indoor unit. However, as compared with control using the superheat degree of the evaporator, effects such as optimization of heat exchange capacity, reduction of the required amount of refrigerant, avoidance of low pressure loss and avoidance of liquid back to the compressor can not be obtained. In addition, when the control based on the degree of superheat on the outlet side of the indoor heat exchanger is performed, it is necessary to change the arrangement of the indoor outlet side temperature sensor. In this case, since the position of the indoor outlet side temperature sensor set in consideration of the productivity etc. is originally changed, the productivity is lowered as a result. In addition, since it is necessary to change the position, a new development load is increased. Thus, in the prior art, the control based on the degree of supercooling can not perform appropriate control for each indoor unit, and when there is an indoor unit unsuitable for the control based on the degree of superheat, the indoor outlet It will be accompanied by the position change of the side temperature sensor.

  The present invention has been made to solve the problems as described above, and while performing control based on the degree of superheat, there is no design change even when there is an indoor unit whose control based on the degree of superheat is not appropriate. It provides an air conditioner.

  The air conditioner according to the present invention comprises a refrigerant circuit in which a compressor, an outdoor heat exchanger, a plurality of expansion parts and a plurality of indoor heat exchangers are connected by piping and a refrigerant flows, and at least a compressor and an outdoor heat exchanger As a mode for controlling the operation of an outdoor unit to be accommodated, a plurality of indoor units respectively accommodating at least a plurality of indoor heat exchangers, and a plurality of expansion units, the degree of outlet superheat of the plurality of indoor heat exchangers during cooling operation A control unit having an overheat control mode for controlling each expansion unit on the basis of the control unit and an overcooling control mode for controlling all expansion units based on the degree of subcooling of the outdoor heat exchanger during cooling operation; The control unit determines that there is an indoor unit unsuitable for the overheat control mode by the determination means for determining whether or not there is an indoor unit unsuitable for the overheat control mode among the plurality of indoor units. If you A switching means for switching from thermal control mode to the subcooling control mode, the.

  According to the present invention, when there is an indoor unit unsuitable for the overheat control mode, the overheat control mode is switched to the overcooling control mode. Therefore, when there is no indoor unit unsuitable for the overheat control mode, control is performed in the overheat control mode, and control is performed in the overcooling control mode only when there is an indoor unit unsuitable for the overheat control mode. Therefore, the design change is not accompanied while maintaining the effect obtained in the overheat control mode as much as possible.

BRIEF DESCRIPTION OF THE DRAWINGS It is a circuit diagram which shows the air conditioner 100 which concerns on Embodiment 1 of this invention. It is a block diagram which shows the control part 30 of the air conditioner 100 which concerns on Embodiment 1 of this invention. It is a Mollier diagram which shows the superheat degree in Embodiment 1 of this invention. It is a Mollier diagram which shows the degree of supercooling in Embodiment 1 of this invention. It is sectional drawing of the indoor heat exchanger 11 in Embodiment 1 of this invention. It is sectional drawing of the indoor heat exchanger 11 in Embodiment 1 of this invention. It is a flowchart which shows operation | movement of the air conditioner 100 which concerns on Embodiment 1 of this invention. It is a circuit diagram which shows the air conditioner 200 which concerns on Embodiment 2 of this invention. It is a circuit diagram which shows the air conditioner 300 which concerns on Embodiment 3 of this invention. It is a circuit diagram which shows the air conditioner 400 which concerns on Embodiment 4 of this invention.

Embodiment 1
Hereinafter, embodiments of an air conditioner according to the present invention will be described with reference to the drawings. FIG. 1 is a circuit diagram showing an air conditioner 100 according to Embodiment 1 of the present invention. The air conditioner 100 will be described based on FIG. As shown in FIG. 1, the air conditioner 100 includes, for example, one outdoor unit 7 and n indoor units 13-1 to 13-n, and the outdoor unit 7 and n indoor units 13- 1 to 13-n are connected by the liquid side extension pipe 8 and the gas side extension pipe 9, respectively.

  The air conditioner 100 is, for example, a multi air conditioner that performs air conditioning using a refrigeration cycle. In the air conditioner 100, for example, all of the n indoor units 13-1 to 13-n perform the cooling operation, and all of the n indoor units 133-1 to 13-n perform the heating operation. And one of the modes is selected. In addition, although the outdoor unit 7 is illustrated about the case where it is one, it may be two or more. Moreover, although the indoor unit 13 is illustrated about the case where it is n unit, it should just be 2 or more. The indoor units 13-1 to 13-n may be collectively referred to as an indoor unit 13.

(Outdoor unit 7, indoor unit 13)
The outdoor unit 7 is installed outdoors, and the compressor 1, the flow path switching device 2, the outdoor heat exchanger 3, the outdoor blower 4, the valve 5 for liquid side extension piping connection, the valve for gas side extension piping connection 6 includes a discharge sensor, an outdoor outlet temperature sensor 15, and an outdoor control device 16. The n indoor units 13-1 to 13-n have expansion units 10-1 to 10-n, indoor heat exchangers 11-1 to 11-n, indoor fans 12-1 to 12-n, and an indoor inlet side, respectively. The temperature sensors 18-1 to 18-n, the indoor outlet side temperature sensors 19-1 to 19-n, and the indoor control devices 17-1 to 17-n are provided. Here, the compressor 1, the flow path switching device 2, the outdoor heat exchanger 3, the n expansion units 10-1 to 10-n, and the n indoor heat exchangers 11-1 to 11-n are connected by piping Thus, the refrigerant circuit 50 in which the refrigerant flows is configured.

  The expandable portions 10-1 to 10-n may be collectively referred to as the expandable portion 10. Moreover, the indoor heat exchangers 11-1 to 11-n may be generically called the indoor heat exchanger 11. Furthermore, the indoor blowers 12-1 to 12-n may be collectively referred to as the indoor blower 12. Furthermore, the indoor inlet temperature sensors 18-1 to 18-n may be collectively referred to as the indoor inlet temperature sensor 18. Further, the indoor outlet side temperature sensors 19-1 to 19-n may be collectively referred to as an indoor outlet side temperature sensor 19. Furthermore, the indoor control devices 17-1 to 17-n may be collectively referred to as an indoor control device 17.

(Refrigerant circuit 50)
The compressor 1 is a device that sucks in a low-temperature low-pressure refrigerant, compresses the sucked refrigerant, and discharges it as a high-temperature high-pressure refrigerant. The flow path switching device 2 is a device that switches the flow direction of the refrigerant in the refrigerant circuit 50, and is, for example, a four-way valve. The outdoor heat exchanger 3 is, for example, a device that exchanges heat between outdoor air and a refrigerant. The outdoor heat exchanger 3 acts as a condenser during the cooling operation and acts as an evaporator during the heating operation. The outdoor blower 4 is an apparatus provided in the vicinity of the outdoor heat exchanger 3 and sending outdoor air to the outdoor heat exchanger 3. The expansion unit 10 is a pressure reducing valve or an expansion valve that decompresses and expands the refrigerant. The expansion unit 10 is, for example, an electronic expansion valve whose opening degree is adjusted. The indoor heat exchanger 11 is, for example, a device that exchanges heat between indoor air and a refrigerant. The indoor heat exchanger 11 acts as an evaporator during the cooling operation, and acts as a condenser during the heating operation. The indoor blower 12 is a device provided in the vicinity of the indoor heat exchanger 11 to send indoor air to the indoor heat exchanger 11.

  The liquid side extension pipe connection valve 5 is a device provided in the vicinity of the liquid side extension pipe 8 connecting the outdoor unit 7 and the indoor unit 13. The liquid side extension pipe connection valve 5 allows or blocks the flow of the refrigerant flowing from one of the outdoor unit 7 and the indoor unit 13 to the other. The gas side extension pipe connection valve 6 is a device provided in the vicinity of the gas side extension pipe 9 connecting the outdoor unit 7 and the indoor unit 13. The gas side extension pipe connection valve 6 permits or blocks the flow of the refrigerant flowing from one of the outdoor unit 7 and the indoor unit 13 to the other.

The pressure sensor 14 is provided in a pipe on the discharge side of the compressor 1 and is a sensor that detects the pressure Pd [kgf / cm ² G] of the refrigerant in the high temperature and high pressure state compressed and discharged by the compressor 1 . The outdoor outlet side temperature sensor 15 is a sensor that detects the outdoor outlet side temperature Tcout [° C.] of the refrigerant flowing to the outlet side of the outdoor heat exchanger 3 during the cooling operation. The indoor inlet side temperature sensor 18 is a sensor for detecting the indoor inlet side temperature Tein [° C.] of the refrigerant flowing to the inlet side of the indoor heat exchanger 11 during the cooling operation. Here, the indoor inlet side temperature of the refrigerant flowing to the inlet side of the indoor heat exchanger 11-n during the cooling operation of the indoor unit 13-n is referred to as Tein-n [° C.]. The indoor outlet side temperature sensor 19 is a sensor that detects the indoor outlet side temperature Teout [° C.] of the refrigerant flowing to the outlet side of the indoor heat exchanger 11 during the cooling operation. Here, the indoor outlet side temperature of the refrigerant flowing to the outlet side of the indoor heat exchanger 11-n during the cooling operation of the indoor unit 13-n is referred to as Teout-n [° C.].

(Control unit 30)
The outdoor control device 16 is provided in the outdoor unit 7 and receives information such as the pressure detected by the pressure sensor 14 and the temperature detected by the outdoor outlet side temperature sensor 15, and various components such as the compressor 1 and the expansion unit 10 It is a device that controls the operation of the actuator. The indoor control device 17 receives information such as the temperature detected by the indoor inlet temperature sensor 18 and the temperature detected by the indoor outlet temperature sensor 19. Further, the indoor control device 17 communicates with the outdoor control device 16 to share each information. Then, the indoor control device 17 adjusts the opening degree of the expansion unit 10, the number of rotations of the indoor fan 12, and the like. The outdoor control device 16 and the indoor control device 17 constitute a control unit 30.

(Control unit 30, calculation means 31)
FIG. 2 is a block diagram showing the control unit 30 of the air conditioner 100 according to Embodiment 1 of the present invention. As shown in FIG. 2, the control unit 30 includes a calculation unit 31, a determination unit 32, and a switching unit 33. The calculation means 31 calculates the degree of superheat SH_e-1 to SH_e-n [of each indoor unit 13 based on the difference between the indoor inlet side temperatures Tein-1 to Tein-n and the indoor outlet side temperatures Teout-1 to Teout-n. deg] is calculated. The degree of superheat is also called superheat. Further, the calculation means 31 calculates the high pressure saturation temperature Ct [° C.] based on the saturation temperature corresponding to the pressure Pd [kgf / cm ² G], and from the high pressure saturation temperature Ct [° C], the outdoor outlet side temperature Tcout [° C. ] Is subtracted to calculate the degree of subcooling SC_hex. The degree of subcooling is also called subcooling.

(Overheat control mode)
The control unit 30 has an overheat control mode and a subcooling control mode as modes for controlling the operation of the plurality of expansion units 10. The overheat control mode is a mode in which each expansion unit 10 is controlled based on the degree of superheat of the outlet side of the plurality of indoor heat exchangers 11 during the cooling operation. The calculation means 31 calculates the degree of superheat SH_e-1 to SH_e-n [of each indoor unit 13 based on the difference between the indoor inlet side temperatures Tein-1 to Tein-n and the indoor outlet side temperatures Teout-1 to Teout-n. Calculate deg]. Then, the control unit 30 sets the superheat degrees SH_e-1 to SH_e-n [deg] closer to the target superheat degrees SHm_e-1 to SHm_e-n [deg], respectively. Control the opening degree.

  FIG. 3 is a Mollier diagram showing the degree of superheat in the first embodiment of the present invention. In FIG. 3, the horizontal axis is specific enthalpy and the vertical axis is pressure. As shown in FIG. 3, the control unit 30 controls the degree of opening of the expansion units 10-1 to 10-n to be controlled to a desired degree of superheat. When the degree of superheat SH_e-1 to SH_e-n is larger than the target degree of superheat SHm_e-1 to SHm_e-n, the control unit 30 sets the target opening degree An = Anf + ΔS1n (Anf: opening of the expansion portion 10 at the current time) Degree, ΔS1 n: correction opening degree by superheat degree control, n = 1, 2,..., N) ΔS1 n of positive degree is set.

  Further, when the degree of superheat SH_e-1 to SH_e-n is smaller than the target degree of superheat SHm_e-1 to SHm_e-n, the control unit 30 sets ΔS1 n to a negative value. The control unit 30 determines whether the degree of superheat SH_e-1 to SH_e-n is SHm_e-1 to SHm_e-n-a1 ≦ SH_e-1 to SH_e-n ≦ SHm_e-1 to SHm_e-1 to SHm_e + n2 (a1: SH_e-1 to SH_e− If the lower limit side stable temperature range [° C] of n, a2: The upper limit side stable temperature range [° C] of SH_e-1 to SH_e-n is satisfied and it is within the opening stable range, set ΔS1 n to zero, The opening degree of the expansion part 10 is maintained.

  As described above, in the overheat control mode, the opening degree of the expansion unit 10 corresponding to the indoor unit 13 can be individually controlled for each indoor unit 13. Here, there may be a gap between the indoor temperature and the set temperature where the indoor units 13 are installed. In the case of a room in which the room temperature and the set temperature are almost equal, the cooling capacity may be small, but in the room in which there is a gap between the room temperature and the set temperature, it is necessary to increase the cooling capacity. That is, in the case of a room where the room temperature and the set temperature are substantially equal, the value of the target degree of superheat SHm_e is increased, and the amount of refrigerant flowing is suppressed by throttling the opening degree of the electronic expansion valve to suppress the cooling capacity. Control is desired. At this time, in the overheat control mode, the degree of opening of the expansion unit 10 corresponding to the indoor unit 13 can be controlled individually, so that the degree of superheat suitable for each indoor unit 13 can be controlled. Therefore, optimal control can be performed in all the indoor units 13.

(Supercooling control mode)
The subcooling control mode is a mode in which all the expansion units 10 are controlled based on the degree of subcooling of the outdoor heat exchanger 3 during the cooling operation. The calculation means 31 calculates the high pressure saturation temperature Ct [° C.] based on the saturation temperature corresponding to the pressure Pd [kgf / cm ² G]. The control unit 30 sets all the expansion units 10-1 to 10-n so that the degree of subcooling SC_hex obtained by subtracting the outdoor outlet temperature Tcout [° C] from the high pressure saturation temperature Ct [° C] approaches the target degree of subcooling SCm_hex. Control the opening degree of

  FIG. 4 is a Mollier diagram showing the degree of subcooling in the first embodiment of the present invention. In FIG. 4, the horizontal axis is specific enthalpy and the vertical axis is pressure. As shown in FIG. 4, the control unit 30 controls the degree of opening of all the expansion units 10 to be controlled to a desired degree of subcooling. When the degree of subcooling SC_hex is larger than the target degree of subcooling SCm_hex, the control unit 30 sets the total target opening degree 合計 A = 10Af + ΔS2 of all expansion units 10 (合計 Af: total opening degree of expansion units 10 at the current time, ΔS2: Set ΔS2 of the correction opening degree by the degree of supercooling control to a positive value. Further, when the degree of subcooling SC_hex is smaller than the target degree of subcooling SCm_hex, the control unit 30 sets ΔS2 to a negative value.

  The control unit 30 has the degree of supercooling SC_hex such that Scm_hex-b1 ≦ SC_hex ≦ Scm_hex + b2 (b1: SC_hex lower limit stable temperature range [° C.], b2: SC_hex upper limit stable temperature range [° C.]) When the temperature is within the stable range, ΔS2 is set to zero, and the opening degree of the expansion portion 10 is maintained. The opening degrees A1 to An of the indoor units 13-1 to 13-n can be obtained from the equation An = .SIGMA.A.times.Cn after .SIGMA.A is calculated. Here, Cn is an evaluation value determined by the capacity band of each indoor unit 13, is stored in the indoor control device 17, and information is transmitted from the indoor control device 17 to the outdoor control device 16 at the time of calculation.

(Judgment means 32)
As shown in FIG. 2, the determination means 32 determines whether or not the indoor unit 13 unsuitable for the overheat control mode is present among the plurality of indoor units 13. Here, the indoor unit 13 compatible with the overheat control mode and the indoor unit 13 unsuitable for the overheat control mode will be described.

(Indoor unit 13 conforming to the overheat control mode)
FIG. 5 is a cross-sectional view of the indoor heat exchanger 11 in the first embodiment of the present invention. As shown in FIG. 5, the indoor heat exchanger 11 has an upper path 11a and a lower path 11b. The upper path 11a is provided at the upper portion of the indoor heat exchanger 11 among the paths through which the refrigerant flows. During the cooling operation, the refrigerant flows in from the first inlet 41 of the upper path 11 a and flows out from the first outlet 42. The lower path 11 b is provided below the indoor heat exchanger 11 among the paths through which the refrigerant flows. During the cooling operation, the refrigerant flows in from the second inlet 43 of the lower path 11 b and flows out from the second outlet 44. Here, the indoor inlet side temperature sensor 18 is provided in the lower path 11 b in the vicinity of the inlet at the time of the cooling operation. In addition, the indoor outlet side temperature sensor 19 is provided in the lower path 11 b in the vicinity of the outlet during the cooling operation.

  As described above, since the indoor outlet side temperature sensor 19 is provided in the vicinity of the outlet of the indoor heat exchanger 11 during the cooling operation, the indoor outlet side temperature Teout [° C.] detected by the indoor outlet side temperature sensor 19 Is close to the actual temperature flowing out of the indoor heat exchanger 11 during the cooling operation. Therefore, the value of the degree of superheat calculated based on the indoor outlet side temperature is close to the value of the actual degree of superheat. Therefore, the indoor unit 13 having the indoor heat exchanger 11 shown in FIG. 5 is adapted to the overheat control mode.

(Indoor unit 13 not suitable for overheat control mode)
FIG. 6 is a cross-sectional view of the indoor heat exchanger 11 in the first embodiment of the present invention. As shown in FIG. 6, the indoor heat exchanger 11 has an upper path 11a and a lower path 11b. The upper path 11a is provided in the upper portion of the heat exchanger among the paths through which the refrigerant flows. During the cooling operation, the refrigerant flows in from the first inlet 41 of the upper path 11 a and flows out from the first outlet 42. The lower path 11b is provided in the lower part of the heat exchanger among the paths through which the refrigerant flows. During the cooling operation, the refrigerant flows in from the second inlet 43 of the lower path 11 b and flows out from the second outlet 44. Here, the indoor inlet side temperature sensor 18 is provided in the lower path 11 b in the vicinity of the inlet at the time of the cooling operation. Further, the indoor outlet side temperature sensor 19 is provided not in the vicinity of the outlet during the cooling operation in the lower path 11 b but in the middle between the inlet and the outlet.

  As described above, since the indoor outlet side temperature sensor 19 is provided in the middle of the indoor heat exchanger 11 during the cooling operation, the indoor outlet side temperature Teout [° C.] detected by the indoor outlet side temperature sensor 19 is The temperature is lower than the actual temperature flowing out of the indoor heat exchanger 11 during the cooling operation. Therefore, the value of the degree of superheat calculated based on the indoor outlet side temperature is lower than the actual degree of superheat. Therefore, when the control unit 30 tries to bring the degree of superheat closer to the target degree of superheat, there is a possibility that the degree of opening of the expansion portion 10 may be narrowed excessively and the degree of superheat may be excessively high. Therefore, the indoor unit 13 having the indoor heat exchanger 11 shown in FIG. 6 may not be suitable for the overheat control mode.

  Here, the indoor control device 17 stores information as to whether or not its own indoor unit 13 is not suitable for the overheat control mode. The outdoor control device 16 constantly transmits and receives information to and from the indoor control device 17 at the time of energization, and immediately recognizes when the indoor unit 13 unsuitable for the overheat control mode is to perform the cooling operation.

  As shown in FIG. 2, the switching means 33 switches from the overheat control mode to the overcooling control mode when it is judged by the judging means 32 that the indoor unit 13 unsuitable for the overheat control mode is present. The supercooling control mode is implemented only when there is an indoor unit 13 unsuitable for the overheating control mode.

(Operation mode, cooling operation)
Next, the operation mode of the air conditioner 100 will be described with reference to FIG. First, the cooling operation will be described. In the cooling operation, the refrigerant drawn into the compressor 1 is compressed by the compressor 1 and discharged in a high-temperature, high-pressure gas state. The refrigerant in the high temperature / high pressure gas state discharged from the compressor 1 passes through the flow path switching device 2 and flows into the outdoor heat exchanger 3 acting as a condenser, and in the outdoor heat exchanger 3, the outdoor fan 4 Heat exchange with the outdoor air sent by The condensed liquid refrigerant flows into each indoor unit 13.

  In each of the indoor units 13, the refrigerant flows into the respective expansion units 10, and is expanded and reduced in pressure in the expansion units 10 to be a low-temperature low-pressure gas-liquid two-phase refrigerant. Then, the refrigerant in the gas-liquid two-phase state flows into the indoor heat exchanger 11 acting as an evaporator, and in the indoor heat exchanger 11, it exchanges heat with the indoor air sent by the indoor blower 12 to be evaporated and gasified. At this time, the indoor air is cooled and cooling is performed indoors. The evaporated low-temperature low-pressure gas refrigerant passes through the flow path switching device 2 and is drawn into the compressor 1.

(Operation mode, heating operation)
Next, the heating operation will be described. In the heating operation, the refrigerant drawn into the compressor 1 is compressed by the compressor 1 and discharged in a high temperature / high pressure gas state. The refrigerant in the high temperature / high pressure gas state discharged from the compressor 1 passes through the flow path switching device 2 and flows into each indoor unit 13. The refrigerant flows into each indoor heat exchanger 11 acting as a condenser, and in the indoor heat exchanger 11, it exchanges heat with indoor air sent by the indoor blower 12, and condenses and liquefies. At this time, indoor air is warmed and heating is performed indoors.

  The condensed liquid refrigerant flows into the expansion unit 10, and is expanded and reduced in pressure in the expansion unit 10 to become a low-temperature low-pressure gas-liquid two-phase refrigerant. Then, the refrigerant in the gas-liquid two-phase state flows into the outdoor heat exchanger 3 acting as an evaporator, and in the outdoor heat exchanger 3, it exchanges heat with the outdoor air sent by the outdoor blower 4 to be vaporized and gasified. The evaporated low-temperature low-pressure gas refrigerant passes through the flow path switching device 2 and is drawn into the compressor 1.

(Operation of control unit 30)
FIG. 7 is a flowchart showing the operation of the air conditioner 100 according to Embodiment 1 of the present invention. Next, the operation of the control unit 30 will be described. When a command to start the cooling operation is transmitted from the indoor unit 13 and the operation of the compressor 1 is started, the control unit 30 controls all the expansion units 10 to the initial opening degree (step ST1). The initial opening degree is set in accordance with the capacity zone of the indoor unit 13 and the conditions of the outside air temperature. Then, it is determined whether or not the fixed time t1 has elapsed (step ST2). Step ST2 is repeated until fixed time t1 passes (No in step ST2). When the fixed time t1 has elapsed (Yes in step ST2), it is determined that the operation is stabilized immediately after the start-up, and the mode shifts to the overheat control mode (step ST3).

  Then, information is stored from the indoor control device 17 by the determination means 32 whether the indoor unit 13 is not suitable for the overheat control mode, and there is an indoor unit 13 not suitable for the overheat control mode? It is determined whether or not it is (step ST4). When it is determined that there is no indoor unit 13 unsuitable for the overheating control mode (No in step ST4), it is determined whether SHm_e-1 to n-a1 ≦ SH_e-1 to n ≦ SHm_e-1 to n + a2 is satisfied. (Step ST5). If SHm_e-1 to n-a1 ≦ SH_e-1 to n ≦ SHm_e-1 to n + a2 is not satisfied (No in step ST5), the superheat degree is controlled using the equation An = Anf + ΔS1 n (step ST6).

  Then, it is determined whether the operation command for the indoor unit 13 is continued (step ST7). When the operation command of the indoor unit 13 is continued (Yes in step ST7), after the predetermined time t2 has elapsed (step ST8), the process returns to step ST4. When the operation command for the indoor unit 13 is not continued in step ST7 (No in step ST7), the control ends. Here, in step ST5, when SHm_e-1 to n-a1 ≦ SH_e-1 to n ≦ SHm_e-1 to n + a2 is satisfied (Yes in step ST5), the process proceeds to step ST7.

  On the other hand, when it is determined in step ST4 that there is an indoor unit 13 unsuitable for the overheating control mode (Yes in step ST4), it is determined whether Scm_hex-b1 ≦ SC_hex ≦ Scm_hex + b2 is satisfied (step ST9). If Scm_hex-b1 ≦ SC_hex ≦ Scm_hex + b2 is not satisfied (No in step ST9), the degree of supercooling is controlled using the equation ΣA = ΣAf + ΔS2 and the equation An = ΣA × Cn (step ST10 and step ST11).

  Then, it is determined whether the operation command for the indoor unit 13 is continued (step ST12). When the operation command of the indoor unit 13 is continued (Yes in step ST12), after the predetermined time t3 has elapsed (step ST13), the process returns to step ST4. Moreover, in step ST12, when the driving | operation instruction | command of the indoor unit 13 is not continued (No of step ST12), control is complete | finished. Here, in step ST9, if Scm_hex-b1 ≦ SC_hex ≦ Scm_hex + b2 is satisfied (Yes in step ST9), the process proceeds to step ST12.

  According to the first embodiment, when there is an indoor unit 13 unsuitable for the overheat control mode, the overheat control mode is switched to the overcooling control mode. Therefore, when there is no indoor unit 13 unsuitable for the overheat control mode, control is performed in the overheat control mode, and control is performed in the overcooling control mode only when there is an indoor unit 13 unsuitable for the overheat control mode. Therefore, the design change is not accompanied while maintaining the effect obtained in the overheat control mode as much as possible.

  Here, with the effect obtained in the overheat control mode, as described above, the opening degree of the expansion unit 10 corresponding to the indoor unit 13 can be individually controlled, and the superheat degree suitable for each indoor unit 13 is controlled. We say that we can do it. Even if the indoor outlet temperature sensor 19 is attached at a position slightly closer to the middle between the inlet and outlet of the indoor heat exchanger 11 due to various reasons such as productivity, the mode is changed to the supercooling mode There is no need to make a design change.

  The air conditioner 100 further includes an indoor outlet temperature sensor 19 for detecting the temperature of the refrigerant flowing to the outlet of the indoor heat exchanger 11 during the cooling operation, and the indoor unit 13 unsuitable for the overheat control mode is The outlet-side temperature sensor 19 is an indoor unit 13 provided midway between the inlet and the outlet of the indoor heat exchanger 11. Thus, even if the indoor unit 13 unsuitable for the overheat control mode is present, the design change is not accompanied while maintaining the effect obtained in the overheat control mode as much as possible.

Second Embodiment
FIG. 8 is a circuit diagram showing an air conditioner 200 according to Embodiment 2 of the present invention. The second embodiment differs from the first embodiment in that the air conditioner 200 includes the storage kit 20. In the second embodiment, the same parts as those of the first embodiment are denoted by the same reference numerals, and the description thereof is omitted. The differences from the first embodiment will be mainly described.

  As shown in FIG. 8, the storage kit 20 includes a plurality of expansion sections 10 and an expansion control device 21. That is, the expansion unit 10 is not provided inside the indoor unit 13. The expansion part 10 of the storage kit 20 is connected to the indoor unit 13 by the indoor machine liquid side extension piping 23-1 to 23-n, respectively. The expansion control device 21 communicates with the outdoor control device 16 and the indoor control device 17 and can share the operation status of various actuators, information from sensors, and the like. As in the second embodiment, even if the expansion unit 10 is stored not in the indoor unit 13 but in the storage kit 20, the overheat control mode and the overcooling control mode are the same as in the first embodiment. Will be implemented. Therefore, the same effects as in the first embodiment can be obtained.

Third Embodiment
FIG. 9 is a circuit diagram showing an air conditioner 300 according to Embodiment 3 of the present invention. The third embodiment is different from the first embodiment in that a plurality of expansion units 10 are provided in the outdoor unit 7. In the third embodiment, the same parts as those of the first embodiment are denoted by the same reference numerals, and the description thereof is omitted. The differences from the first embodiment will be mainly described.

  As shown in FIG. 9, a plurality of expansion units 10 are provided inside the outdoor unit 7 at positions downstream of the liquid-side extension pipe connection valve 5 during cooling operation. That is, the expansion unit 10 is not provided inside the indoor unit 13. In addition, the gas side extension pipe 9 is branched into n in the outdoor unit 7 and connected to the indoor unit 13. As in the third embodiment, even if the expansion unit 10 is stored not in the indoor unit 13 but in the outdoor unit 7, the overheat control mode and the overcooling control mode are the same as in the first embodiment. Will be implemented. Therefore, the same effects as in the first embodiment can be obtained.

Fourth Embodiment
FIG. 10 is a circuit diagram showing an air conditioner 400 according to Embodiment 4 of the present invention. The fourth embodiment is different from the first embodiment in that the air conditioner 100 includes the outdoor intermediate temperature sensor 22. In the fourth embodiment, the same parts as those of the first embodiment are denoted by the same reference numerals, and the description thereof is omitted. The differences from the first embodiment will be mainly described.

  As shown in FIG. 10, the outdoor intermediate temperature sensor 22 is a sensor which is provided at the intermediate portion of the outdoor heat exchanger 3 and detects the outdoor intermediate temperature of the refrigerant flowing to the intermediate portion of the outdoor heat exchanger 3. The air conditioner 400 does not have the pressure sensor 14. The calculation means 31 directly calculates the high pressure saturation temperature Ct [° C.] based on the outdoor intermediate temperature detected by the outdoor intermediate temperature sensor 22. In this case, since the high pressure saturation temperature can be directly calculated without calculating the saturation temperature from the pressure once, the processing speed of the control unit 30 can be improved.

  DESCRIPTION OF SYMBOLS 1 compressor, 2 flow-path switching apparatus, 3 outdoor heat exchanger, 4 outdoor fan, 5 valve for liquid side extension piping connection, 6 valve for gas side extension piping connection, 7 outdoor unit, 8, 8-1, 8- 2, 8-n liquid side extension piping, 9, 9-1, 9-2, 9-n Gas side extension piping, 10, 10-1, 10-2, 10-n expansion part, 11, 11-1, 11-2, 11-n indoor heat exchanger, 11a upper path, 11b lower path, 12, 12-1, 12-2, 12-n indoor fan, 13, 13-1, 13-2, 13-n indoor , 14 pressure sensor, 15 outdoor outlet temperature sensor, 16 outdoor controller, 17, 17-1, 17-2, 17-n indoor controller, 18, 18-1, 18-2, 18-n indoor inlet Side temperature sensor, 19, 19-1, 19-2, 19-n Indoor outlet temperature sensor, 2 Storage kit, 21 expansion control device, 22 outdoor intermediate temperature sensor, 23, 23-1, 23-2, 23-n indoor unit liquid side extension piping, 50 refrigerant circuit, 30 control unit, 31 calculation means, 32 judgment means, 33 switching means, 41 first inlet, 42 first outlet, 43 second inlet, 44 second outlet, 100, 200, 300, 400 air conditioner.

Claims (6)

A refrigerant circuit in which a compressor, an outdoor heat exchanger, a plurality of expansion parts, and a plurality of indoor heat exchangers are connected by piping and a refrigerant flows;
An outdoor unit accommodating at least the compressor and the outdoor heat exchanger;
A plurality of indoor units each accommodating at least a plurality of the indoor heat exchangers;
As a mode for controlling the operation of the plurality of expansion units, an overheat control mode for controlling each of the expansion units based on the outlet side superheat degree of the plurality of indoor heat exchangers during the cooling operation; A control unit having a subcooling control mode for controlling all the expansion units based on the degree of subcooling of the exchanger.
The control unit
A determination unit that determines whether or not there is an indoor unit unsuitable for the overheat control mode among the plurality of indoor units;
An air conditioner comprising: switching means for switching from the overheat control mode to the overcooling control mode when it is determined by the determination means that there is an indoor unit unsuitable for the overheat control mode. It further comprises an indoor outlet side temperature sensor for detecting the indoor outlet side temperature of the refrigerant flowing to the outlet side of the indoor heat exchanger during cooling operation,
The indoor unit unsuitable for the above-mentioned overheating control mode is
The indoor outlet side temperature sensor is an indoor unit provided midway between an inlet and an outlet of the indoor heat exchanger,
The control unit
The air conditioner according to claim 1, wherein information on whether the indoor unit is unsuitable for the overheat control mode is stored. The air conditioner according to claim 1, further comprising a storage kit for storing a plurality of the expansion portions. The air conditioner according to claim 1, wherein a plurality of the expansion units are accommodated in the outdoor unit. A pressure sensor that detects the pressure of the refrigerant flowing to the discharge side of the compressor;
An outdoor outlet temperature sensor for detecting the outdoor outlet temperature of the refrigerant flowing to the outlet of the outdoor heat exchanger during the cooling operation;
The control unit
The air according to any one of claims 1 to 4, further comprising calculation means for calculating the degree of subcooling based on the pressure detected by the pressure sensor and the temperature detected by the outdoor outlet side temperature sensor. Harmonizer. An intermediate temperature sensor for detecting an outdoor intermediate temperature of the refrigerant flowing to an intermediate portion of the outdoor heat exchanger;
An outdoor outlet temperature sensor for detecting the outdoor outlet temperature of the refrigerant flowing to the outlet of the outdoor heat exchanger during the cooling operation;
The control unit
The calculation method of calculating the degree of supercooling based on the outdoor intermediate temperature detected by the intermediate temperature sensor and the temperature detected by the outdoor outlet side temperature sensor is further included. Air conditioner as described.

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