JP6229170B2 - Refrigeration cycle equipment - Google Patents

Description

  The present invention relates to control of a refrigeration cycle apparatus such as an air conditioner.

  In the conventional air conditioner, if the discharge temperature of the compressor is below the limit value, the opening degree of the throttle device is controlled so that the suction superheat degree of the compressor becomes a predetermined temperature, and the discharge temperature of the compressor is the limit value. When the pressure exceeds the value, the opening degree of the expansion device is controlled so that the discharge temperature of the compressor becomes a predetermined value (for example, Patent Document 1).

JP 2001-174075 A

  However, when the control target is switched from the suction superheat degree to the discharge temperature, if the difference between the target discharge temperature and the current discharge temperature is large, the opening of the expansion device is greatly changed, the flow rate of the refrigerant is greatly increased or decreased, and the discharge temperature is changed. Try to get close to the target suddenly. For this reason, in a device having a large heat capacity of the compressor and a slow reaction of changes in the discharge temperature, the throttle device may be excessively throttled or opened too much, and the discharge temperature may fluctuate greatly.

  In order to suppress this fluctuation, the fluctuation of the discharge temperature can be reduced by reducing the opening change of the expansion device or slowing the timing of the opening change (slowing the flow change of the expansion device). However, if the flow rate change of the throttle device is excessively slowed, there is a problem that the control is not in time when it is desired to suddenly lower the discharge temperature, such as when the discharge temperature rises to a dangerous level.

  In order to solve the conventional problem, the present invention provides a flow rate of refrigerant that passes through the expansion device so that, when the discharge temperature exceeds a predetermined discharge temperature, the discharge temperature becomes a discharge temperature set value. The discharge temperature setting value is adjusted based on the discharge temperature when the predetermined discharge temperature is exceeded, and is changed according to the discharge temperature and the target discharge temperature setting value.

  With the present invention, it is possible to avoid a decrease in comfort and efficiency due to sudden fluctuations in the flow rate of the throttle device, a decrease in equipment reliability such as deterioration of refrigeration oil and deterioration of compressor motor due to excessive increase in discharge temperature, and comfortable. Highly reliable equipment can be supplied.

Refrigeration cycle diagram in the embodiment of the present invention Control block diagram in the embodiment of the present invention Flowchart in Embodiment 1 of the present invention Flowchart in Embodiment 2 of the present invention Flowchart in Embodiment 3 of the present invention Flowchart in Embodiment 4 of the present invention Flowchart in the fifth embodiment of the present invention

  1st invention is equipped with the compressor, the condenser, the expansion device, the evaporator, and the discharge temperature detection part which detects the temperature of the refrigerant | coolant discharged from the said compressor, The discharge temperature which the said discharge temperature detection part detects Is a refrigeration cycle apparatus in which the flow rate of the refrigerant passing through the throttle device is adjusted so that the discharge temperature exceeds a predetermined discharge temperature so that the discharge temperature is discharged to the target discharge temperature setting value. The refrigerant flow rate passing through the throttle device is adjusted so as to be a temperature set value, and the discharge temperature set value is based on the discharge temperature when the predetermined discharge temperature is exceeded, and the discharge temperature and It is changed according to the target discharge temperature set value.

  According to this, since the throttle amount of the throttle device is changed by a change amount corresponding to the change of the discharge temperature, the discharge temperature can be gradually brought close to the target discharge temperature set value. For this reason, it is possible to avoid a decrease in comfort and efficiency due to sudden fluctuations in the flow rate of the throttle device, a decrease in equipment reliability such as deterioration of refrigeration oil and compressor motor due to excessive increase in discharge temperature, and it is comfortable and reliable. High-quality equipment can be supplied.

  In the first aspect of the present invention, a suction superheat degree calculation unit that calculates the superheat degree of the refrigerant sucked into the compressor is provided, and the discharge temperature setting is set according to the suction superheat degree calculated by the suction superheat degree calculation unit. The value is to be changed. According to this, the throttle amount of the throttle device can be changed by the change amount according to the change of the discharge temperature and the degree of superheat of suction.

  In particular, the second invention includes a suction superheat degree calculation unit that calculates the superheat degree of the refrigerant sucked into the compressor in the first invention, and the suction superheat degree calculated by the suction superheat degree calculation part is: When the degree of superheat is larger than the predetermined superheat degree, the discharge temperature set value is not changed. According to this, in a state where the suction superheat degree is large and the discharge temperature rapidly rises, the amount of change in the throttle of the throttle device can be reduced.

  A third invention includes a suction superheat degree calculation unit that calculates a superheat degree of the refrigerant sucked into the compressor in the first invention, and the suction superheat degree calculated by the suction superheat degree calculation part is a predetermined value. When the degree of superheat is greater, the discharge temperature set value is lowered. According to this, in a state where the suction superheat degree is large and the discharge temperature rapidly increases, the amount of change in the throttle of the throttle device can be further reduced.

  According to a fourth aspect, in the first aspect, when the difference between the discharge temperature and the discharge temperature set value is smaller than a predetermined temperature difference, the discharge temperature set value is increased. According to this, in a state where the discharge temperature is stable, that is, in a state where the discharge temperature does not rapidly increase, the amount of change in the aperture of the aperture device can be increased. Therefore, the discharge temperature can be quickly adjusted to the target discharge temperature set value.

  In a fifth aspect based on the first aspect, when the discharge temperature set value is higher than the target discharge temperature set value by a predetermined temperature or more, the discharge temperature set value is lowered. According to this, it is possible to prevent the discharge temperature from fluctuating periodically.

  The above invention is particularly effective in the case of using a refrigerant whose discharge temperature rapidly increases when the suction superheat degree exceeds a certain value. This is because it is possible to suppress large fluctuations in the discharge temperature that are likely to occur due to the control of the diaphragm device at the conventional discharge temperature.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
1 is a refrigeration cycle diagram of the air-conditioning apparatus according to Embodiment 1 of the present invention, FIG. 2 is a control block diagram, and FIG. 3 is a flowchart.

  In FIG. 1, an outdoor unit 1 includes an inverter-driven capacity (frequency) variable compressor 2 (hereinafter simply referred to as a compressor), an outdoor heat exchanger 3, an outdoor blower 4, and a four-way valve 5 for switching between heating and cooling. And are provided. A compressor discharge temperature detection device (discharge temperature detection unit) 15 is provided on the discharge pipe connected to the compressor 2 or the top surface of the compressor 2, and the compressor intake temperature is provided on the suction pipe connected to the compressor 2. A detection device (intake temperature detection unit) 16 is provided. The outdoor heat exchanger 3 is provided with an outdoor heat exchanger temperature detection device 17.

  On the other hand, the indoor unit 7 is provided with an indoor blower 8 and an indoor heat exchanger 9. The indoor heat exchanger 9 is provided with an indoor heat exchanger temperature detection device 18.

  The outdoor unit 1 includes a liquid side connection portion 13 and a gas side connection portion 14. The outdoor unit 1 is connected to the indoor unit 7 by connection piping connected to the liquid side connection unit 13 and the gas side connection unit 14.

  The refrigerant liquid pipe 11, which is a pipe connecting the liquid side connecting portion 13 and the outdoor heat exchanger 3, is provided with an electric expansion valve 6, which is a throttling device capable of pulse-controlling the valve opening by a stepping motor, for example. It has been.

  The compressor 2, the outdoor heat exchanger 3, the four-way valve 5, the electric expansion valve 6, and the indoor heat exchanger 9 are connected in a ring shape to form a refrigeration cycle circuit. R32 (difluoromethane) is enclosed as a refrigerant in the refrigeration cycle circuit. R32 is a refrigerant having a tendency that the discharge temperature of the compressor 2 rapidly increases when the suction superheat degree of the compressor 2 exceeds a certain value.

  In addition, the indoor unit 7 is provided with an operation setting device 10 that sets an operation mode (cooling, dehumidification or heating) desired by a resident, a target room temperature, and instructs operation or stop. The operation setting device 10 is, for example, a remote controller.

  The outdoor unit 1 includes a control device that adjusts the rotational speed of the compressor 2, the rotational speed of the outdoor blower 4, the switching of the four-way valve 5, the opening degree of the electric expansion valve 6, and the like according to the setting of the operation setting device 10. 20 is provided.

  During the cooling or dehumidifying operation, the outdoor heat exchanger 3 serves as a condenser, and the indoor heat exchanger 9 serves as an evaporator. For this reason, the indoor heat exchanger temperature detector 18 serves as an evaporator temperature detector. During the heating operation, the indoor heat exchanger 9 serves as a condenser, and the outdoor heat exchanger 3 serves as an evaporator. For this reason, the outdoor heat exchanger temperature detector 17 serves as an evaporator temperature detector.

  In the refrigeration cycle apparatus having the above configuration, during cooling or dehumidifying operation, the refrigerant discharged from the compressor 2 flows to the outdoor heat exchanger 3 through the four-way valve 5, and the outdoor fan 4 is driven to drive the outdoor heat exchanger. 3 heat-exchanges with outdoor air and condensates. Thereafter, the flow rate of the refrigerant passes through the refrigerant liquid pipe 11 and is controlled by the electric expansion valve 6. The refrigerant decompressed by the electric expansion valve 6 evaporates in the indoor heat exchanger 9 of the indoor unit 7 and then is sucked into the compressor 2 again through the refrigerant gas pipe 12 and the four-way valve 5.

  Since this electric expansion valve 6 is pulse-controlled by a stepping motor or the like so as to have an opening corresponding to the load in the room, the refrigerant is adjusted to a flow rate corresponding to the room load.

On the other hand, during the heating operation, the refrigerant discharged from the compressor 2 flows to the indoor heat exchanger 9 through the four-way valve 5, and exchanges heat with indoor air in the indoor heat exchanger 9 by driving the indoor blower 8. To condense. Thereafter, the flow rate of the refrigerant is controlled by the electric expansion valve 6. The refrigerant decompressed by the electric expansion valve 6 evaporates in the outdoor heat exchanger 3 and then is sucked into the compressor 2 again through the four-way valve 5.

  FIG. 2 is a control block diagram of the present embodiment. The electric expansion valve 6 is connected to the control device. The control device includes an output relay circuit that controls a stepping motor and the like, and a determination device that outputs a signal to the output relay circuit. The determination device is connected to the compressor discharge temperature detection device 15, the compressor suction temperature detection device 16, the outdoor heat exchanger temperature detection device 17, the indoor heat exchanger temperature detection device 18, and the suction superheat degree detection device 19. The suction superheat degree detection device (suction superheat degree calculation unit) 19 is configured to suck the compressor 2 from the detected values of the compressor suction temperature detection device 16, the outdoor heat exchanger temperature detection device 17, and the indoor heat exchanger temperature detection device 18. The degree of superheat is calculated.

  The determination device determines, based on the outputs of these detection devices, the target discharge temperature set value, the suction superheat degree set value, the discharge temperature set value calculated from these outputs, and the predetermined discharge temperature determination value. The electric expansion valve 6 is adjusted to the calculated opening.

  Next, the control of the present embodiment will be described using the flowchart of FIG.

  The resident selects, for example, cooling with the operation setting device 10 and instructs the start of operation. When the compressor 2 starts operation (S000), the compressor discharge temperature detector 15 detects the compressor discharge temperature (hereinafter simply referred to as discharge temperature) (Td) (S001).

  The discharge temperature (Td) is compared with a predetermined discharge temperature determination value (TdA) (S002). When the discharge temperature (Td) is equal to or lower than the discharge temperature determination value (TdA) (No in S002), the suction superheat degree (SH) of the compressor 2 is detected (S003).

  The suction superheat degree (SH) is compared with a predetermined suction superheat degree set value (SHA) (S004). When the intake superheat degree (SH) is higher than the intake superheat degree set value (SHA) (Yes in S004), the electric expansion valve 6 is opened A (PLS) in the opening direction (S005). When the suction superheat degree (SH) is lower than the suction superheat degree set value (SHA) (No in S004), the suction superheat degree (SH) is compared with “suction superheat degree set value (SHA) -1 ° C.” ( S006). When the suction superheat degree (SH) is not less than “suction superheat degree set value (SHA) -1 ° C.” and not more than the suction superheat degree set value (SHA) (No in S006), the electric expansion valve 6 is not opened / closed. (S007). If the suction superheat degree (SH) is smaller than “suction superheat degree set value (SHA) −1 ° C.” (Yes in S006), the electric expansion valve 6 is closed B (PLS) in the closing direction (S008). Thus, the control is performed so as to keep the suction superheat degree (SH) at a certain appropriate value (SHA).

  That is, when the discharge temperature (Td) is smaller than the discharge temperature determination value (TdA), the opening / closing of the electric expansion valve 6 is adjusted by the suction SH control.

  The number of pulses in the opening direction A (PLS) and the closing direction B (PLS) of the electric expansion valve 6 is determined by the difference between the suction superheat degree (SH) and the suction superheat degree setting value (SHA). Is set to a large number of pulses.

In the case of cooling, the intake superheat degree is determined based on the indoor heat exchanger temperature detected from the indoor heat exchanger temperature detection device 18 from the compressor intake temperature detected from the compressor intake temperature detection device 16 (during cooling). (Evaporation temperature) is reduced. If this difference is large, the degree of superheat sucked into the compressor 2 increases, so that the refrigerating machine oil of the compressor 2 due to a decrease in efficiency of the compressor 2 or an increase in the temperature of the refrigerant discharged from the compressor 2. Cause deterioration of compressors and compressor motors. If this difference is small, liquid-rich refrigerant is sucked into the compressor 2, leading to a reduction in efficiency of the compressor 2 and mechanical damage due to a large amount of liquid. For this reason, it is necessary to control the suction superheat degree with an appropriate value.

  Note that, in the case of heating, the suction superheat degree is determined based on the outdoor heat exchanger temperature detected from the outdoor heat exchanger temperature detection device 17 based on the compressor suction temperature detected from the compressor suction temperature detection device 16 (during heating). (Evaporation temperature) is reduced.

  On the other hand, when the discharge temperature (Td) becomes higher than the discharge temperature value (TdA) (Yes in S002), the discharge temperature (Td) at that time is set as the initial discharge temperature setting value (Td1) (S009). Further, an appropriate target discharge temperature (from the temperature detected by the indoor heat exchanger temperature detection device 18 (evaporation temperature during cooling) and the temperature detected from the outdoor heat exchanger temperature detection device 17 (condensation temperature during cooling)). TdX) is calculated (S010). Then, the discharge temperature set value (Td1) is gradually increased until the discharge temperature set value (Td1) reaches the target discharge temperature (TdX).

  A method for changing the temperature will be described. The discharge temperature (Td) is compared with the discharge temperature set value (Td1) (S011). When the discharge temperature (Td) becomes higher than the discharge temperature set value (Td1) (Yes in S011), the electric expansion valve 6 is opened C (PLS) in the opening direction (S012). When the discharge temperature (Td) is lower than the discharge temperature set value (Td1) (No in S012), the discharge temperature (Td) is compared with “discharge temperature set value (Td1) −1 ° C.” (S013). When the discharge temperature (Td) is equal to or higher than “discharge temperature set value (Td1) −1 ° C.” and equal to or lower than the discharge temperature set value (Td1) (No in S013), the electric expansion valve 6 is not opened or closed (S014). . When the discharge temperature (Td) is lower than “discharge temperature set value (Td1) −1 ° C.” (Yes in S013), the electric expansion valve 6 is closed D (PLS) in the closing direction (S015). Thus, the discharge temperature (Td) is controlled to be kept at the discharge temperature set value (Td1).

  Thereafter, the target discharge temperature (TdX) is compared with the discharge temperature set value (Td1) (S016). When the discharge temperature set value (Td1) is lower than the appropriate target discharge temperature (TdX) (Yes in S016), the discharge temperature set value (Td1) is increased by Ta ° C. (S017). Thereafter, the process returns to S011, and the electric expansion valve 6 is opened and closed again at a certain interval aiming at the increased discharge temperature set value (Td1). By repeating this operation, the discharge temperature set value (Td1) is controlled so as to gradually approach the appropriate target discharge temperature (TdX). When the discharge temperature set value (Td1) reaches an appropriate target discharge temperature (TdX) (No in S016), the discharge temperature set value (Td1) is not changed (S018).

  That is, when the discharge temperature (Td) is higher than the discharge temperature determination value (TdA), the discharge temperature control for gradually increasing the discharge temperature setting value (Td1) temporarily set to open / close the electric expansion valve 6. Adjust with.

  The number of pulses in the opening direction C (PLS) and the closing direction D (PLS) of the electric expansion valve is determined by the difference between the discharge temperature (Td) and the discharge temperature set value (Td1). It is set to be a number.

  When switching from the suction SH control to the discharge temperature control, if the difference between the discharge temperature (Td) and the appropriate target discharge temperature (TdX) is large, the opening / closing of the electric expansion valve 6 is greatly changed to rapidly change the refrigerant circulation amount. Thus, the discharge temperature (Td) is abruptly brought closer to the target discharge temperature (TdX). When the heat capacity of the compressor 2 is large, the change speed of the discharge temperature (Td) is slow. Therefore, the electric expansion valve 6 opens or closes too much, and the discharge temperature (Td) fluctuates greatly and becomes unstable.

However, in this embodiment, when switching from the suction SH control to the discharge temperature control, the discharge temperature (Td) is set as the initial discharge temperature set value (Td1), and the discharge temperature set value (Td1) is set as the target discharge temperature (TdX). By gradually increasing until reaching the value, the difference between the discharge temperature (Td) and the discharge temperature set value (Td1) is always small, so the opening and closing of the electric expansion valve 6 is also reduced, and the fluctuation of the discharge temperature (Td) is suppressed. It is done.

  When the electric expansion valve 6 opens and closes greatly, the refrigerant circulation rate fluctuates greatly, resulting in a decrease in comfort due to a change in the capacity of the device (a variation in the blowing temperature), a decrease in efficiency, and a decrease in reliability (due to an excessive increase in the discharge temperature). Cause deterioration of refrigeration oil, deterioration of compressor motor, etc.), but can be avoided by this control, and it becomes possible to supply comfortable and highly reliable equipment.

  The appropriate target discharge temperature (TdX) is predicted so that the suction state of the compressor 2 is optimized from the evaporation temperature, the condensation temperature, the optimum suction SH, the compressor motor efficiency, the outdoor unit temperature, and the indoor unit temperature. The calculated discharge temperature of the compressor 2 is calculated in the same manner as the target value in the conventional discharge temperature control, and therefore the details are omitted here.

(Embodiment 2)
FIG. 4 is a flowchart of control in the second embodiment. Since the configuration of the refrigeration cycle and the control block configuration are the same as those in the first embodiment, the description thereof is omitted.

  The resident selects, for example, cooling with the operation setting device 10 and instructs the start of operation. When the compressor 2 starts operation (S100), the compressor discharge temperature detection device 15 detects the compressor discharge temperature (Td) (S101).

  When the discharge temperature (Td) is equal to or lower than the discharge temperature value (TdA) (No in S102), the suction superheat degree (SH) of the compressor 2 is detected (S103), and the suction superheat degree (SH) is the suction superheat. When it is higher than the degree set value (SHA) (Yes in S104), the electric expansion valve 6 is opened A (PLS) in the opening direction (S105).

  When the suction superheat degree (SH) is not less than “suction superheat degree set value (SHA) −1 ° C.” and not more than the suction superheat degree set value (SHA) (No in S106), the electric expansion valve 6 is not opened / closed. (S107).

  If the suction superheat degree (SH) is smaller than “suction superheat degree set value (SHA) −1 ° C.” (Yes in S106), the electric expansion valve 6 is closed B (PLS) in the closing direction (S108). Thus, the control is performed so as to keep the suction superheat degree (SH) at a certain appropriate value (SHA).

  The number of pulses in the opening direction A (PLS) and the closing direction B (PLS) of the electric expansion valve 6 is determined by the difference between the suction superheat degree (SH) and the suction superheat degree setting value (SHA). Is set to a large number of pulses.

  In the case of cooling, the intake superheat degree is determined based on the indoor heat exchanger temperature detected from the indoor heat exchanger temperature detection device 18 from the compressor intake temperature detected from the compressor intake temperature detection device 16 (during cooling). (Evaporation temperature) is reduced. When this difference is large, the suction superheat degree of the compressor 2 is increased, the efficiency of the compressor 2 is decreased, the deterioration of the refrigerating machine oil of the compressor 2 due to the temperature of the refrigerant discharged from the compressor 2 is increased, It causes deterioration of the compressor motor. If this difference is small, liquid-rich refrigerant is sucked into the compressor 2, leading to a reduction in efficiency of the compressor 2 and mechanical damage due to a large amount of liquid. For this reason, it is necessary to control the suction superheat degree with an appropriate value.

On the other hand, when the discharge temperature (Td) becomes higher than the discharge temperature value (TdA) (Yes in S102), the discharge temperature (Td) at that time is set as the initial discharge temperature setting value (Td1) (S109).
An appropriate target discharge temperature (TdX) from the temperature detected from the indoor heat exchanger temperature detection device 18 (evaporation temperature during cooling) and the temperature detected from the outdoor heat exchanger temperature detection device 17 (condensation temperature during cooling). ) Is calculated (S110).

  The discharge temperature set value (Td1) is gradually increased until the discharge temperature set value (Td1) reaches the target discharge temperature (TdX).

  That is, when the discharge temperature (Td) becomes higher than the discharge temperature set value (Td1) (Yes in S111), the electric expansion valve 6 is opened C (PLS) in the opening direction (S112). When the discharge temperature (Td) is equal to or higher than “discharge temperature set value (Td1) −1 ° C.” and equal to or lower than the discharge temperature set value (Td1) (No in S113), the electric expansion valve 6 is not opened or closed (S114). . When the discharge temperature (Td) is lower than the discharge temperature set value (Td1) -1 ° C. (Yes in S113), the electric expansion valve 6 is closed D (PLS) in the opening direction (S115). Thus, the discharge temperature (Td) is controlled to be kept at the discharge temperature set value (Td1).

  Thereafter, the target discharge temperature (TdX) is compared with the discharge temperature set value (Td1) (S116). When the discharge temperature set value (Td1) is lower than the appropriate target discharge temperature (TdX) (Yes in S116), the suction superheat degree (SH) of the compressor 2 is detected (S117). Then, the suction superheat degree (SH) is compared with a second predetermined suction superheat degree set value (SHB) (S118). When the suction superheat degree (SH) is lower than the suction superheat degree set value (SHB) (Yes in S118), the discharge temperature set value (Td1) is raised by Ta ° C. (S119). Thereafter, the process returns to S111, and the electric expansion valve 6 is opened and closed again at a certain interval aiming at the increased discharge temperature set value (Td1).

  When the suction superheat degree (SH) is equal to or higher than the suction superheat degree set value (SHB) (No in S118), the suction superheat degree of the compressor 2 is large, and the discharge temperature set value (Td1) is increased to increase the electric expansion valve 6. When the is closed in the closing direction, the degree of superheated suction is further increased and the discharge temperature is rapidly increased, so that the discharge temperature set value (Td1) is not increased (S120).

  By repeating the above operation, the discharge temperature set value (Td1) is controlled so as to gradually approach the appropriate target discharge temperature (TdX), and the discharge temperature set value (Td1) becomes the appropriate target discharge temperature (TdX). When it reaches (No in S116), the discharge temperature set value (Td1) is not changed (S120).

  The number of pulses in the opening direction C (PLS) and the closing direction D (PLS) of the electric expansion valve is determined by the difference between the discharge temperature (Td) and the discharge temperature set value (Td1). It is set to be a number.

  In the present embodiment, when switching from the suction SH control to the discharge temperature control, the discharge temperature (Td) is set to the initial discharge temperature set value (Td1), and the discharge temperature set value (Td1) reaches the target discharge temperature (TdX). The discharge temperature set value (Td1) is gradually increased until the suction superheat degree (SH) is equal to or higher than the suction superheat degree set value (SHB) until the discharge temperature set value (Td1) is not increased. The discharge temperature set value (Td1) is controlled.

  As a result, the difference between the discharge temperature (Td) and the discharge temperature set value (Td1) is always kept small, whereby the opening and closing of the electric expansion valve 6 is also made small and fluctuations in the discharge temperature (Td) are suppressed.

When the electric expansion valve 6 opens and closes greatly, the refrigerant circulation rate fluctuates greatly, resulting in a decrease in comfort due to a change in the capacity of the device (a variation in the blowing temperature), a decrease in efficiency, and a decrease in reliability (due to an excessive increase in discharge temperature). Deterioration of refrigeration oil and compressor motor) can be avoided by this control, and it is possible to supply comfortable and reliable equipment.

  Further, the discharge temperature set value (Td1) is increased or not increased according to the suction superheat degree (SH) until the discharge temperature set value (Td1) reaches the target discharge temperature (TdX). , Rapid fluctuations in the discharge temperature (Td) can be suppressed.

(Embodiment 3)
FIG. 5 is a flowchart of control in the third embodiment. Since the configuration of the refrigeration cycle and the control block configuration are the same as those in the first embodiment, the description thereof is omitted.

  The resident selects, for example, cooling with the operation setting device 10 and instructs the start of operation. When the compressor 2 starts operation (S200), the compressor discharge temperature detection device 15 detects the compressor discharge temperature (Td) (S201).

  When the discharge temperature (Td) is equal to or lower than the discharge temperature value (TdA) (No in S202), the suction superheat degree (SH) of the compressor 2 is detected (S203), and the suction superheat degree (SH) is the suction superheat. When it is higher than the degree set value (SHA) (Yes in S204), the electric expansion valve 6 is opened A (PLS) in the opening direction (S205).

  When the suction superheat degree (SH) is not less than “suction superheat degree set value (SHA) −1 ° C.” and not more than the suction superheat degree set value (SHA) (No in S206), the electric expansion valve 6 is not opened / closed. (S207).

  When the suction superheat degree (SH) is smaller than “suction superheat degree set value (SHA) −1 ° C.” (Yes in S206), the electric expansion valve 6 is closed B (PLS) in the closing direction (S208). Thus, the control is performed so as to keep the suction superheat degree (SH) at a certain appropriate value (SHA).

  The number of pulses in the opening direction A (PLS) and the closing direction B (PLS) of the electric expansion valve 6 is determined by the difference between the suction superheat degree (SH) and the suction superheat degree setting value (SHA). Is set to a large number of pulses.

  In the case of cooling, the intake superheat degree is determined based on the indoor heat exchanger temperature detected from the indoor heat exchanger temperature detection device 18 from the compressor intake temperature detected from the compressor intake temperature detection device 16 (during cooling). (Evaporation temperature) is reduced. When this difference is large, the suction superheat degree of the compressor 2 is increased, the efficiency of the compressor 2 is decreased, the deterioration of the refrigerating machine oil of the compressor 2 due to the temperature of the refrigerant discharged from the compressor 2 is increased, It causes deterioration of the compressor motor. If this difference is small, liquid-rich refrigerant is sucked into the compressor 2, leading to a reduction in efficiency of the compressor 2 and mechanical damage due to a large amount of liquid. For this reason, it is necessary to control the suction superheat degree with an appropriate value.

  On the other hand, when the discharge temperature (Td) becomes higher than the discharge temperature value (TdA) (Yes in S202), the discharge temperature (Td) at that time is set as the initial discharge temperature setting value (Td1) (S209), and the indoor heat An appropriate target discharge temperature (TdX) is calculated from the temperature detected from the exchanger temperature detection device 18 (evaporation temperature during cooling) and the temperature detected from the outdoor heat exchanger temperature detection device 17 (condensation temperature during cooling). (S210).

  The discharge temperature set value (Td1) is gradually increased until the discharge temperature set value (Td1) reaches the target discharge temperature (TdX).

That is, when the discharge temperature (Td) becomes higher than the discharge temperature set value (Td1) (Y in S211)
es), the electric expansion valve 6 is opened C (PLS) in the opening direction (S212). When the discharge temperature (Td) is equal to or higher than “discharge temperature set value (Td1) −1 ° C.” and equal to or lower than the discharge temperature set value (Td1) (No in S213), the electric expansion valve 6 is not opened or closed (S214). . When the discharge temperature (Td) is lower than “discharge temperature set value (Td1) −1 ° C.” (Yes in S213), the electric expansion valve 6 is closed D (PLS) in the closing direction (S215).

  Thus, the discharge temperature (Td) is controlled to be kept at the discharge temperature set value (Td1).

  Thereafter, the target discharge temperature (TdX) is compared with the discharge temperature set value (Td1) (S216). When the discharge temperature set value (Td1) is lower than the appropriate target discharge temperature (TdX) (Yes in S216), the suction superheat degree (SH) of the compressor 2 is detected (S217). When the suction superheat degree (SH) is lower than the suction superheat degree set value (SHB) (Yes in S218), the discharge temperature set value (Td1) is increased by Ta ° C. (S219). Thereafter, the process returns to S211, and the electric expansion valve 6 is opened and closed again at a certain interval, aiming at the increased discharge temperature set value (Td1).

  When the intake superheat degree (SH) is equal to or higher than the intake superheat degree set value (SHB) (No in S218), the intake superheat degree of the compressor 2 is large, and the discharge temperature set value (Td1) is increased to increase the electric expansion valve 6. When the valve is closed in the closing direction, the degree of superheat of suction is further increased and the discharge temperature is rapidly increased, so that the discharge temperature set value (Td1) is lowered by Tb ° C. (S222). Tb may be the same value as Ta or a different value.

  When the discharge temperature set value (Td1) is equal to or higher than the appropriate target discharge temperature (TdX) (No in S216), the suction superheat degree (SH) is compared with the suction superheat degree set value (SHB) (S220). . When the intake superheat degree (SH) is equal to or higher than the intake superheat degree set value (SHB) (No in S220), the intake superheat degree is large, the discharge temperature set value (Td1) is increased, and the electric expansion valve 6 is moved in the closing direction. When closed, the suction superheat degree further increases and the discharge temperature rises rapidly, so the discharge temperature set value (Td1) is lowered by Tb ° C. (S222).

  When the suction superheat degree (SH) is lower than the suction superheat degree set value (SHB) (Yes in S220), the discharge temperature set value (Td1) is maintained (S221).

  By repeating the above operation, the discharge temperature set value (Td1) is controlled to gradually approach the appropriate target discharge temperature (TdX).

  The number of pulses in the opening direction C (PLS) and the closing direction D (PLS) of the electric expansion valve is determined by the difference between the discharge temperature (Td) and the discharge temperature set value (Td1). It is set to be a number.

  In the present embodiment, when switching from the suction SH control to the discharge temperature control, the discharge temperature (Td) is set to the initial discharge temperature set value (Td1), and the discharge temperature set value (Td1) reaches the target discharge temperature (TdX). The discharge temperature set value (Td1) is gradually increased until the suction superheat degree (SH) is equal to or higher than the suction superheat degree set value (SHB) until the discharge temperature set value (Td1) is lowered. The temperature set value (Td1) is controlled.

  As a result, the difference between the discharge temperature (Td) and the discharge temperature set value (Td1) is always kept small, whereby the opening and closing of the electric expansion valve 6 is also made small and fluctuations in the discharge temperature (Td) are suppressed.

When the electric expansion valve 6 opens and closes greatly, the refrigerant circulation rate fluctuates greatly, resulting in a decrease in comfort due to a change in the capacity of the device (a variation in the blowing temperature), a decrease in efficiency, and a decrease in reliability (due to an excessive increase in discharge temperature). Deterioration of refrigeration oil and compressor motor) can be avoided by this control, and it is possible to supply comfortable and reliable equipment.

  Further, the discharge temperature set value (Td1) is increased, maintained, or decreased according to the suction superheat degree (SH) until the discharge temperature set value (Td1) reaches the target discharge temperature (TdX). , Rapid fluctuations in the discharge temperature (Td) can be suppressed.

(Embodiment 4)
FIG. 6 is a flowchart of control in the fourth embodiment. Since the configuration of the refrigeration cycle and the control block configuration are the same as those in the first embodiment, the description thereof is omitted.

  The resident selects, for example, cooling with the operation setting device 10 and instructs the start of operation. When the compressor 2 starts operation (S300), the compressor discharge temperature detection device 15 detects the compressor discharge temperature (Td) (S301).

  When the discharge temperature (Td) is equal to or lower than the discharge temperature value (TdA) (No in S302), the suction superheat degree (SH) of the compressor 2 is detected (S303), and the suction superheat degree (SH) is the suction superheat. When it is higher than the degree set value (SHA) (Yes in S304), the electric expansion valve 6 is opened A (PLS) in the opening direction (S305).

  When the suction superheat degree (SH) is not less than “suction superheat degree set value (SHA) -1 ° C.” and not more than the suction superheat degree set value (SHA) (No in S306), the electric expansion valve 6 is not opened / closed. (S307).

  When the suction superheat degree (SH) is smaller than “suction superheat degree set value (SHA) −1 ° C.” (Yes in S306), the electric expansion valve 6 is closed B (PLS) in the closing direction (S308). Thus, the control is performed so as to keep the suction superheat degree (SH) at a certain appropriate value (SHA).

  The number of pulses in the opening direction A (PLS) and the closing direction B (PLS) of the electric expansion valve 6 is determined by the difference between the suction superheat degree (SH) and the suction superheat degree setting value (SHA). Is set to a large number of pulses.

  In the case of cooling, the intake superheat degree is determined based on the indoor heat exchanger temperature detected from the indoor heat exchanger temperature detection device 18 from the compressor intake temperature detected from the compressor intake temperature detection device 16 (during cooling). (Evaporation temperature) is reduced. If this difference is large, the suction superheat degree of the compressor 2 becomes large, so that the efficiency of the compressor 2 is reduced, and the refrigerant oil of the compressor 2 is deteriorated due to the temperature of the refrigerant discharged from the compressor 2 becoming large. And causes deterioration of the compressor motor. If this difference is small, liquid-rich refrigerant is sucked into the compressor 2, leading to a reduction in efficiency of the compressor 2 and mechanical damage due to a large amount of liquid. For this reason, it is necessary to control the suction superheat degree with an appropriate value.

  On the other hand, when the discharge temperature (Td) becomes higher than the discharge temperature value (TdA) (Yes in S302), the discharge temperature (Td) at that time is set as the initial discharge temperature setting value (Td1) (S309), and the indoor heat An appropriate target discharge temperature (TdX) is calculated from the temperature detected from the exchanger temperature detection device 18 (evaporation temperature during cooling) and the temperature detected from the outdoor heat exchanger temperature detection device 17 (condensation temperature during cooling). (S310).

  The discharge temperature set value (Td1) is gradually increased until the discharge temperature set value (Td1) reaches the target discharge temperature (TdX).

  That is, when the discharge temperature (Td) becomes higher than the discharge temperature set value (Td1) (Yes in S311), the electric expansion valve 6 is opened C (PLS) in the opening direction (S312). When the discharge temperature (Td) is equal to or higher than “discharge temperature set value (Td1) −1 ° C.” and equal to or lower than the discharge temperature set value (Td1) (No in S313), the electric expansion valve 6 is not opened or closed (S314). . When the discharge temperature (Td) is lower than “discharge temperature set value (Td1) −1 ° C.” (Yes in S313), the electric expansion valve 6 is closed D (PLS) in the closing direction (S315).

  Thus, the discharge temperature (Td) is controlled to be kept at the discharge temperature set value (Td1).

  Thereafter, the target discharge temperature (TdX) is compared with the discharge temperature set value (Td1) (S316). When the discharge temperature set value (Td1) is lower than the appropriate target discharge temperature (TdX) (Yes in S316), the suction superheat degree (SH) of the compressor 2 is detected (S317). Then, the suction superheat degree (SH) is compared with a second predetermined suction superheat degree set value (SHB) (S318). Further, the discharge temperature set value (Td1) is compared with a value obtained by subtracting a set value X (for example, 1 ° C.) from the discharge temperature set value (Td1) (S319).

  When the suction superheat degree (SH) is lower than the suction superheat degree set value (SHB) (Yes in S318) and the discharge temperature (Td) is higher than “discharge temperature set value (Td1) −X ° C.”, that is, the discharge temperature When the difference between the discharge temperature setting value (Td1) approaches X ° C. (here, for example, 1 ° C.) (Yes in S319), the discharge temperature setting value (Td1) is increased by Ta ° C. (S320). Thereafter, the process returns to S311, and the electric expansion valve 6 is opened and closed again at a certain interval aiming at the increased discharge temperature set value (Td1).

  When the temperature difference between the discharge temperature (Td) and the discharge temperature set value (Td1) is equal to or higher than X ° C. (No in S319), the discharge temperature set value (Td1) is maintained (S322). According to this, when the temperature difference becomes large, the opening and closing of the electric expansion valve 6 changes greatly, and the circulation amount of the refrigerant changes abruptly, so that it is possible to avoid the discharge temperature (Td) from fluctuating greatly and becoming unstable. .

  When the discharge temperature set value (Td1) is lower than the appropriate target discharge temperature (TdX) (Yes in S316) and the suction superheat degree (SH) is equal to or higher than the suction superheat degree set value (SHB) (No in S318), If the suction superheat degree is large and the discharge temperature set value (Td1) is increased and the electric expansion valve 6 is closed in the closing direction, the suction superheat degree further increases and the discharge temperature rises rapidly, so the discharge temperature set value (Td1) Is lowered by Tb ° C. (S323).

  Further, when the discharge temperature set value (Td1) is equal to or higher than the appropriate target discharge temperature (TdX) (No in S316) and the suction superheat degree (SH) is equal to or higher than the suction superheat degree set value (SHB) (Yes in S321). ), The suction superheat degree is large, and when the discharge temperature set value (Td1) is increased and the electric expansion valve 6 is closed in the closing direction, the suction superheat degree further increases and the discharge temperature rises rapidly. The value (Td1) is lowered by Tb ° C. (S323).

  Further, when the discharge temperature set value (Td1) is equal to or higher than the appropriate target discharge temperature (TdX) (No in S316) and the suction superheat (SH) is lower than the suction superheat set value (SHB) (S321). Maintains the discharge temperature set value (Td1) (S322).

  By repeating the above operation, the discharge temperature set value (Td1) is controlled to gradually approach the appropriate target discharge temperature (TdX).

  The number of pulses in the opening direction C (PLS) and the closing direction D (PLS) of the electric expansion valve is determined by the difference between the discharge temperature (Td) and the discharge temperature set value (Td1). It is set to be a number.

  In the present embodiment, when switching from the suction SH control to the discharge temperature control, the discharge temperature (Td) is set to the initial discharge temperature set value (Td1), and the discharge temperature set value (Td1) reaches the target discharge temperature (TdX). The discharge temperature set value (Td1) is gradually increased until the suction superheat degree (SH) is equal to or higher than the suction superheat degree set value (SHB) until the discharge temperature set value (Td1) is lowered. The temperature set value (Td1) is controlled.

  As a result, the difference between the discharge temperature (Td) and the discharge temperature set value (Td1) is always kept small, whereby the opening and closing of the electric expansion valve 6 is also made small and fluctuations in the discharge temperature (Td) are suppressed.

  When the electric expansion valve 6 opens and closes greatly, the refrigerant circulation rate fluctuates greatly, resulting in a decrease in comfort due to a change in the capacity of the device (a variation in the blowing temperature), a decrease in efficiency, and a decrease in reliability (due to an excessive increase in the discharge temperature). Deterioration of refrigeration oil and compressor motor) can be avoided by this control, and it is possible to supply comfortable and reliable equipment.

  Further, until the discharge temperature set value (Td1) reaches the target discharge temperature (TdX), the discharge temperature set value (Td1) is increased or maintained according to the suction superheat degree (SH) and the discharge temperature (Td). Therefore, rapid fluctuations in the discharge temperature (Td) can be suppressed.

(Embodiment 5)
FIG. 7 is a flowchart of control in the fifth embodiment. Since the configuration of the refrigeration cycle and the control block configuration are the same as those in the first embodiment, the description thereof is omitted.

  The resident selects, for example, cooling with the operation setting device 10 and instructs the start of operation. When the compressor 2 starts operation (S400), the compressor discharge temperature detection device 15 detects the compressor discharge temperature (Td) (S401).

  When the discharge temperature (Td) is equal to or lower than the discharge temperature value (TdA) (No in S402), the suction superheat degree (SH) of the compressor 2 is detected (S403), and the suction superheat degree (SH) is the suction superheat. When it is higher than the degree set value (SHA) (Yes in S404), the electric expansion valve 6 is opened A (PLS) in the opening direction (S405).

  When the suction superheat degree (SH) is equal to or higher than “suction superheat degree set value (SHA) -1 ° C.” and lower than the suction superheat degree set value (SHA) (No in S406), the electric expansion valve 6 is not opened / closed. (S407).

  If the suction superheat degree (SH) is smaller than “suction superheat degree set value (SHA) −1 ° C.” (Yes in S406), the electric expansion valve 6 is closed B (PLS) in the closing direction (S408). Thus, the control is performed so as to keep the suction superheat degree (SH) at a certain appropriate value (SHA).

  The number of pulses in the opening direction A (PLS) and the closing direction B (PLS) of the electric expansion valve 6 is determined by the difference between the suction superheat degree (SH) and the suction superheat degree setting value (SHA). Is set to a large number of pulses.

In the case of cooling, the intake superheat degree is determined based on the indoor heat exchanger temperature detected from the indoor heat exchanger temperature detection device 18 from the compressor intake temperature detected from the compressor intake temperature detection device 16 (during cooling). (Evaporation temperature) is reduced. When this difference is large, the suction superheat degree of the compressor 2 is increased, the efficiency of the compressor 2 is decreased, the deterioration of the refrigerating machine oil of the compressor 2 due to the temperature of the refrigerant discharged from the compressor 2 is increased, It causes deterioration of the compressor motor. Moreover, if this difference is small, liquid-rich refrigerant will be sucked into the compressor 2, and the efficiency of the compressor 2 may be reduced,
It leads to mechanical damage due to the large amount of liquid. For this reason, it is necessary to control with an appropriate value.

  On the other hand, when the discharge temperature (Td) becomes higher than the discharge temperature value (TdA) (Yes in S402), the discharge temperature (Td) at that time is set as the initial discharge temperature setting value (Td1) (S409), and the indoor heat An appropriate target discharge temperature (TdX) is calculated from the temperature detected from the exchanger temperature detection device 18 (evaporation temperature during cooling) and the temperature detected from the outdoor heat exchanger temperature detection device 17 (condensation temperature during cooling). (S410).

  The discharge temperature set value (Td1) is gradually increased until the discharge temperature set value (Td1) reaches the target discharge temperature (TdX).

  That is, when the discharge temperature (Td) becomes higher than the discharge temperature set value (Td1) (Yes in S411), the electric expansion valve 6 is opened C (PLS) in the opening direction (S412). When the discharge temperature (Td) is equal to or higher than “discharge temperature set value (Td1) −1 ° C.” and equal to or lower than the discharge temperature set value (Td1) (No in S413), the electric expansion valve is not opened or closed (S314). When the discharge temperature (Td) is lower than “discharge temperature set value (Td1) −1 ° C.” (Yes in S413), the electric expansion valve 6 is closed D (PLS) in the closing direction (S415). Thus, the discharge temperature (Td) is controlled to be kept at the discharge temperature set value (Td1).

  Thereafter, the target discharge temperature (TdX) is compared with the discharge temperature set value (Td1) (S416). When the discharge temperature set value (Td1) is lower than the appropriate target discharge temperature (TdX) (Yes in S416), the suction superheat degree (SH) of the compressor 2 is detected (S417). Then, the suction superheat degree (SH) is compared with a second predetermined suction superheat degree setting value (SHB) (S418). Further, the discharge temperature set value (Td1) is compared with a value obtained by subtracting a set value X (for example, 1 ° C.) from the discharge temperature set value (Td1) (S419).

  When the suction superheat degree (SH) is lower than the suction superheat degree set value (SHB) (Yes in S418) and the discharge temperature (Td) is higher than “discharge temperature set value (Td1) −X ° C.”, that is, the discharge temperature When the difference between the discharge temperature setting value (Td1) approaches X ° C. (here, for example, 1 ° C.) (Yes in S419), the discharge temperature setting value (Td1) is increased by Ta ° C. (S420). Thereafter, the process returns to S411, and the electric expansion valve 6 is opened and closed again at a certain interval aiming at the increased discharge temperature set value (Td1).

  When the temperature difference between the discharge temperature (Td) and the discharge temperature set value (Td1) is equal to or higher than X ° C. (No in S419), the discharge temperature set value (Td1) is maintained (S424). According to this, when the temperature difference becomes large, the opening and closing of the electric expansion valve 6 changes greatly, and the circulation amount of the refrigerant changes abruptly, so that it is possible to avoid the discharge temperature (Td) from fluctuating greatly and becoming unstable. .

  When the discharge temperature set value (Td1) is lower than the appropriate target discharge temperature (TdX) (Yes in S416) and the suction superheat degree (SH) is equal to or higher than the suction superheat degree set value (SHB) (No in S418), If the suction superheat degree is large and the discharge temperature set value (Td1) is increased and the electric expansion valve 6 is closed in the closing direction, the suction superheat degree further increases and the discharge temperature rises rapidly, so the discharge temperature set value (Td1) Is lowered by Tb ° C. (S425).

  On the other hand, when the discharge temperature set value (Td1) is equal to or higher than the appropriate target discharge temperature (TdX) (No in S416), the discharge temperature set value (Td1) and the set value Y from the discharge temperature set value (Td1). A value obtained by adding (for example, 2 ° C.) is compared (S421). When the discharge temperature setting value (Td1) does not exceed the target discharge temperature (TdX) by more than Y ° C. (for example, 2 ° C. here) (S421), the suction superheat degree (SH) is set to the suction superheat degree set value (SHB). (S423).

  When the intake superheat degree (SH) is equal to or higher than the intake superheat degree set value (SHB) (No in S423), the intake superheat degree is large and the discharge temperature set value (Td1) is increased to move the electric expansion valve 6 in the closing direction. When closed, the degree of suction superheat further increases and the discharge temperature rises rapidly, so the discharge temperature set value (Td1) is lowered by Tb ° C. (S425).

  When the suction superheat degree (SH) is smaller than the suction superheat degree set value (SHB) (Yes in S423), the discharge temperature set value (Td1) is not lowered and maintained (S424).

  When the discharge temperature set value (Td1) is equal to or higher than the appropriate target discharge temperature (TdX) (No in S416) and TdX exceeds Y ° C. or more (No in S421), the discharge temperature set value (Td1) Is lowered by Tc ° C. so as to approach the appropriate target discharge temperature (TdX) (S422). Tc may be the same value as Ta or Tb, or may be a different value.

  When the discharge temperature set value (Td1) exceeds an appropriate target discharge temperature (TdX), if the discharge temperature set value (Td1) is immediately lowered, the electric expansion valve 6 is opened, the refrigerant flow rate is increased, and the discharge temperature is increased. Decreases. When the discharge temperature decreases, the electric expansion valve 6 closes this time, and the discharge temperature increases again by decreasing the refrigerant flow rate. By repeating this, the discharge temperature varies. However, in the present embodiment, stability is improved by lowering the discharge temperature setting value (Td1) by Tc ° C. only when the discharge temperature setting value (Td1) greatly exceeds the appropriate target discharge temperature (TdX). .

  By repeating the above operation, the discharge temperature set value (Td1) is controlled to gradually approach the appropriate target discharge temperature (TdX).

  The number of pulses in the opening direction C (PLS) and the closing direction D (PLS) of the electric expansion valve is determined by the difference between the discharge temperature (Td) and the discharge temperature set value (Td1). It is set to be a number.

  In the present embodiment, when switching from the suction SH control to the discharge temperature control, the discharge temperature (Td) is set to the initial discharge temperature set value (Td1), and the discharge temperature set value (Td1) reaches the target discharge temperature (TdX). The discharge temperature set value (Td1) is gradually increased until the suction superheat degree (SH) is equal to or higher than the suction superheat degree set value (SHB) until the discharge temperature set value (Td1) is lowered. The temperature set value (Td1) is controlled.

  As a result, the difference between the discharge temperature (Td) and the discharge temperature set value (Td1) is always kept small, whereby the opening and closing of the electric expansion valve 6 is also made small and fluctuations in the discharge temperature (Td) are suppressed.

  When the electric expansion valve 6 opens and closes greatly, the refrigerant circulation rate fluctuates greatly, resulting in a decrease in comfort due to a change in the capacity of the device (a variation in the blowing temperature), a decrease in efficiency, and a decrease in reliability (due to an excessive increase in the discharge temperature). Deterioration of refrigeration oil and compressor motor) can be avoided by this control, and it is possible to supply comfortable and reliable equipment.

  Further, until the discharge temperature set value (Td1) reaches the target discharge temperature (TdX), the discharge temperature set value (Td1) is increased or maintained according to the suction superheat degree (SH) and the discharge temperature (Td). Therefore, rapid fluctuations in the discharge temperature (Td) can be suppressed. In particular, stability is improved by slightly reducing the discharge temperature setting value (Td1) only when the discharge temperature setting value (Td1) greatly exceeds the target discharge temperature (TdX).

In the above embodiment, 1 ° C. of “suction superheat setting value (SHA) −1 ° C.” and “discharge temperature setting value (Td1) −1 ° C.” may not be 1 ° C., for example, It may be several degrees Celsius.

  As described above, this embodiment connects an outdoor unit having a variable capacity compressor, an outdoor heat exchanger, a blower, a four-way valve, a throttle device, an indoor heat exchanger, and an indoor unit having a blower, and at least The indoor unit is provided with an indoor heat exchanger temperature detection device that detects the temperature of the indoor heat exchanger, and at least the compressor discharge temperature detection device that detects the temperature of the refrigerant discharged from the compressor in the outdoor unit and the outdoor heat exchange An outdoor heat exchanger temperature detection device for detecting the compressor temperature and a compressor suction temperature detection device for detecting the temperature of the refrigerant sucked into the compressor, and suction superheat for detecting the degree of superheat on the suction side of the compressor The throttle device is controlled so that the value of the suction superheat temperature detected from the degree detection device becomes a predetermined temperature. When the discharge temperature detected from the compressor discharge temperature detection device exceeds a predetermined temperature, The above The discharge temperature detected from the compressor discharge temperature detection device is the target discharge temperature calculated from the evaporation temperature and the condensation temperature detected from the indoor heat exchanger temperature detection device and the outdoor heat exchanger temperature detection device. In the air conditioner that controls the expansion device, when the discharge temperature exceeds the predetermined temperature and the control is switched to the discharge temperature, the discharge temperature at the time of switching is set as the initial discharge temperature setting value, and the discharge temperature is set while monitoring the change in the discharge temperature. Gradually change the value to reach the target discharge temperature.

  As a method of gradually changing, when the value of the suction superheat degree detection device exceeds a predetermined temperature, the discharge temperature set value is maintained or slightly lowered, and the value of the suction superheat degree detection device has a predetermined temperature. Only in the following cases, the discharge temperature set value is slightly increased.

  However, if the discharge temperature is below a certain temperature with respect to the discharge temperature set value, that is, if the discharge temperature is considerably lower than the discharge temperature set value, the temperature of the discharge temperature set value is Do not raise.

  Further, only when the temperature difference between the discharge temperature and the discharge temperature set value is equal to or less than a predetermined temperature, that is, when the discharge temperature approaches the value of the discharge temperature set value, the value of the discharge temperature set value is slightly increased.

  Further, when the discharge temperature set value exceeds the target discharge temperature, the value of the discharge temperature set value is decreased only when the temperature difference between the discharge temperature set value and the target temperature set value is equal to or higher than a predetermined temperature. That is, it is lowered only when the discharge temperature set value greatly exceeds the target temperature set value, and the discharge temperature set value is not lowered when the discharge temperature set value is slightly exceeded.

  As a result, it is possible to avoid a decrease in comfort and efficiency due to sudden fluctuations in the flow rate of the throttle device, a decrease in equipment reliability such as deterioration of refrigeration oil and deterioration of compressor motor due to excessive increase in discharge temperature, and it is comfortable and reliable. High-quality equipment can be supplied.

  As described above, the refrigeration cycle apparatus according to the present invention can avoid large fluctuations in the discharge temperature, appropriately control the expansion valve, and improve comfort and reliability. It can also be applied to multi-air conditioners for buildings.

DESCRIPTION OF SYMBOLS 1 Outdoor unit 2 Compressor 3 Outdoor heat exchanger 4 Outdoor fan 5 Four way valve 6 Electric expansion valve 7 Indoor unit 8 Indoor fan 9 Indoor heat exchanger 10 Operation setting apparatus 11 Refrigerant liquid pipe 12 Refrigerant gas pipe 13 Liquid side connection part 14 Gas side connection 15 Compressor discharge temperature detection device 16 Compressor suction temperature detection device 17 Outdoor heat exchanger temperature detection device 18 Indoor heat exchanger temperature detection device 19 Suction superheat degree detection device 20 Control device

Claims (5)

A compressor, a condenser, a throttling device, an evaporator, and a discharge temperature detector for detecting the temperature of the refrigerant discharged from the compressor;
A refrigeration cycle apparatus in which a refrigerant flow rate passing through the throttle device is adjusted so that a discharge temperature detected by the discharge temperature detection unit becomes a target discharge temperature set value;
When the discharge temperature exceeds a predetermined discharge temperature, the refrigerant flow rate that passes through the expansion device is adjusted so that the discharge temperature becomes a discharge temperature setting value.
The refrigeration cycle apparatus, wherein the discharge temperature set value is changed according to the discharge temperature and the target discharge temperature set value with reference to the discharge temperature when the predetermined discharge temperature is exceeded. A suction superheat degree calculation unit that calculates the superheat degree of the refrigerant sucked into the compressor, and the discharge temperature setting when the suction superheat degree calculated by the suction superheat degree calculation unit is larger than a predetermined superheat degree The refrigeration cycle apparatus according to claim 1, wherein the value is not changed. A suction superheat degree calculation unit that calculates the superheat degree of the refrigerant sucked into the compressor, and the discharge temperature setting when the suction superheat degree calculated by the suction superheat degree calculation unit is larger than a predetermined superheat degree The refrigeration cycle apparatus according to claim 1, wherein the value is lowered. 2. The refrigeration cycle apparatus according to claim 1, wherein when the difference between the discharge temperature and the discharge temperature set value is smaller than a predetermined temperature difference, the discharge temperature set value is increased. 2. The refrigeration cycle apparatus according to claim 1, wherein when the discharge temperature set value is higher than the target discharge temperature set value by a predetermined temperature or more, the discharge temperature set value is lowered.