REFRIGERATION CIRCUIT AND CONTROL METHOD

Abstract

Refrigeration circuit assembly (1) comprising a compressor (4), a condenser (7), an expansion valve (6), an evaporator (5), an internal fan (3), a control device (2) that controls the speed of the internal fan (3) and the frequency of the compressor (4), a room temperature sensor (11) that detects a room temperature, and an evaporation temperature sensor (12) that detects an evaporation temperature of a refrigerant in the evaporator (5). The control device (2) comprises a room temperature control unit (211) that calculates the speed of the internal fan (3) at which the room temperature is caused to approach a predetermined room temperature, and an evaporation temperature control unit (212) that calculates the frequency of the compressor (4) at which the evaporation temperature is caused to approach a predetermined refrigerant temperature.The room temperature is individually controlled by the internal fan (3) and the evaporation temperature is individually controlled by the compressor (4).

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a refrigeration cycle device and a control method. STATE OF THE ART

[0002] A refrigeration cycle device forming a refrigerant circuit in which a refrigerant circulates is generally known (see, for example, patent reference 1). PRIOR ART PATENT REFERENCES

[0003] Patent Reference 1: Publication of Japanese Patent Application No. H09-14724 SUMMARY OF THE INVENTION TASK TO BE SOLVED BY THE INVENTION

[0004] Conventionally, a technique of switching between cooling mode to maintain a comfortable room temperature and dehumidification mode to maintain a comfortable room humidity has been used. However, it is difficult for conventional technology to maintain a comfortable room temperature and humidity.

[0005] It is therefore an object of the present disclosure to individually control a room temperature and a room humidity to maintain a comfortable room temperature and a comfortable room humidity. MEANS TO SOLVED THE TASK

[0006] A refrigeration cycle device according to the present disclosure comprises: a compressor that compresses a refrigerant; a capacitor; an expansion valve; an evaporator; an indoor fan; a control device that controls the speed of the indoor fan and the frequency of the compressor; a room temperature sensor that detects a room temperature; and an evaporation temperature sensor that detects an evaporation temperature of a refrigerant in the evaporator, wherein the control device comprises a room temperature control unit having a control unit that calculates the indoor fan speed at which the room temperature is caused to approach a predetermined room temperature, and an evaporation temperature control unit having a control unit that calculates the frequency of the compressor at which the evaporation temperature is caused to approach a predetermined refrigerant temperature, and where the room temperature is individually controlled by the indoor fan and the evaporation temperature is individually controlled by the compressor.

[0007] A control method according to the present disclosure is a control method in a refrigeration cycle device including a compressor that compresses a refrigerant, a condenser, an expansion valve, an evaporator, an indoor fan, a control device that controls a rotational speed of the indoor fan and a frequency of the compressor, a room temperature sensor that detects a room temperature, and an evaporation temperature sensor that detects an evaporation temperature of a refrigerant in the evaporator, and the method comprises: Calculating the indoor fan speed at which the room temperature is caused to approach a predetermined room temperature; and Calculating the frequency of the compressor at which the evaporating temperature is caused to approach a predetermined refrigerant temperature, where the room temperature is individually controlled by the indoor fan and the evaporation temperature is individually controlled by the compressor. EFFECTS OF THE INVENTION

[0008] According to the present disclosure, a room temperature and a room humidity are individually controlled so that a comfortable room temperature and a comfortable room humidity can be maintained. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a diagram schematically showing an example of the configuration of a refrigeration cycle device according to a first embodiment. Fig. 2 is a block diagram schematically showing a configuration of a Fig. 1 shows the control device. Fig. 3 is a functional block diagram showing the functions of the Fig. 1 shows the control device. Fig. 4 is a flowchart schematically showing an example of a control method for controlling a room temperature and an evaporating temperature in the refrigeration cycle device. Fig. 5 is a functional block diagram showing another example of a control device. Fig. 6 is a functional block diagram showing another example of a control device. Fig. 7 is a functional block diagram showing another example of a control device. Fig. 8 is a diagram showing a comparison between the operation in a conventional refrigeration cycle device and the operation in the refrigeration cycle device according to the first embodiment. Fig. 9 is a diagram showing an operating range of the refrigeration cycle device. Fig. 10 is a functional block diagram showing another example of a control device. Fig. 11 is a flowchart showing an example of a method for controlling a frequency of the compressor so that an evaporating temperature approaches a target evaporating temperature. MODE FOR CARRYING OUT THE INVENTION

[0009] A refrigeration cycle device 1 according to the present disclosure will be described with reference to the drawings. Note that the components designated by the same reference numerals in the drawings correspond to the same or corresponding components, and this applies throughout the application. FIRST EXAMPLE OF IMPLEMENTATION

[0010] Fig. 1 is a diagram schematically showing an example of a configuration of a refrigeration cycle device 1 according to a first embodiment.

[0011] As in Fig. 1, the refrigeration cycle device 1 comprises a control device 2, an indoor fan 3, a compressor 4 that compresses a refrigerant, an evaporator 5, an electronic expansion valve 6 that serves as an expansion valve, a condenser 7, a room temperature sensor 11, and an evaporation temperature sensor 12. The compressor 4, the evaporator 5, the electronic expansion valve 6, and the condenser 7 are connected to one another by a pipe 9 and form a refrigerant circuit 10. A refrigerant flows in the refrigerant circuit 10. In Fig. 1 the solid arrows indicate the flow direction of the refrigerant.

[0012] The refrigeration cycle device 1 may further include a four-way valve, an accumulator (also called a "liquid trap"), an injection circuit, a receiver circuit, or a power receiver circuit. The four-way valve is located on a pipe connected to an inlet and an outlet of the compressor 4, respectively, and switches a refrigerant gas. The accumulator is located between the compressor 4 and the evaporator 5 and prevents refrigerant not vaporized by the evaporator from being sucked into the compressor. The injection circuit suppresses an increase in the outlet temperature of the compressor 4. The receiver circuit or the power receiver circuit is located between the condenser 7 and the evaporator 5 and stores a redundant refrigerant. The following description refers to a case where the refrigeration cycle device 1 is an air conditioner, but the refrigeration cycle device 1 is not limited to air conditioners.

[0013] The indoor fan 3 draws room air into the refrigeration cycle device 1 (e.g., the indoor unit of the air conditioner) and discharges cool or warm air, which undergoes heat exchange, into the room. In the indoor fan 3, the indoor fan speed (i.e., the drive speed) is controlled by a control circuit, such as an inverter circuit. In this case, the control circuit can change the indoor fan speed of the indoor fan 3. This changes the airflow rate of the indoor fan 3. That is, the amount of air moved by the indoor fan 3 per unit time changes. It is sufficient if the resolution of the indoor fan speed of the indoor fan 3 is 100 rpm or less.

[0014] Compressor 4 compresses a refrigerant and discharges the compressed refrigerant. The drive frequency of compressor 4 can be varied, for example, by a control circuit such as an inverter circuit. In this case, the air flow rate of compressor 4 changes. That is, the amount of refrigerant delivered by compressor 4 per unit of time changes.

[0015] The evaporator 5 performs a heat exchange between a refrigerant and the air, evaporates the refrigerant and cools the air.

[0016] The electronic expansion valve 6, for example, is an expansion valve whose opening degree can be adjusted. The electronic expansion valve 6 controls the outlet temperature of the compressor 4 and the intake superheat of the compressor 4, but does not control the evaporation temperature with a specific target value.

[0017] The condenser 7 performs heat exchange between a refrigerant and air, condenses the refrigerant to liquefy it, and heats the air.

[0018] As in Fig. 1, the refrigeration circuit device 1 comprises, for example, the room temperature sensor 11 and the evaporation temperature sensor 12.

[0019] Room temperature sensor 11 is located, for example, at an inlet of the air conditioning system's indoor unit. Room temperature sensor 11 measures the temperature in a room. In particular, room temperature sensor 11 measures the temperature of the room air drawn into the indoor unit. The temperature of the room air drawn into the indoor unit is also referred to as the "room temperature."

[0020] The temperature detected by room temperature sensor 11 can, for example, be the ambient temperature of a remote control unit for operating the air conditioning system. In this case, the air temperature detected by the remote control unit is sent, for example, to room temperature sensor 11.

[0021] The temperature detected by room temperature sensor 11 can, for example, be the air temperature detected by a temperature sensor located in the room. In this case, the air temperature detected by the temperature sensor is forwarded to room temperature sensor 11, for example.

[0022] The temperature detected by the room temperature sensor 11 can, for example, be an air temperature detected by an infrared sensor in the indoor unit of the air conditioner. In this case, the thermal image information detected by the infrared sensor, which indicates the air temperature, is sent to the room temperature sensor 11, for example.

[0023] The evaporation temperature sensor 12 is located, for example, in the piping 9 on the outlet side of the evaporator 5. The evaporation temperature sensor 12 detects the evaporation temperature of the refrigerant in the evaporator 5. The evaporation temperature sensor 12 is formed, for example, by a thermocouple, a thermistor, a pressure sensor, or other devices. In the case of the thermocouple and the thermistor, the evaporation temperature sensor 12 detects the temperature of a two-phase region (i.e., a region where gas and liquid are mixed) in the heat exchanger of the indoor unit. In the case of the pressure sensor, the evaporation temperature sensor 12 detects a pressure in the heat exchanger of the indoor unit and converts the pressure into a saturation temperature to use the saturation temperature as the evaporation temperature. The evaporation temperature sensor 12 can also detect information corresponding to an evaporation temperature, for example, instead of the evaporation temperature.a low pressure.

[0024] Fig. 2 is a block diagram schematically showing a configuration of the Fig. 1 shows the control device 2.

[0025] As in Fig. 2, the above-described sensors are connected to the control device 2, and the temperature data of the sensors are input to the control device 2. An instruction or the like from a user of the refrigeration cycle device 1 is input to the control device 2 via the operation unit (not shown). The control device 2 is included in at least one indoor unit and / or outdoor unit of the air conditioner. That is, the control device 2 may be included in both the indoor unit and the outdoor unit of the air conditioner, or in one of the indoor and outdoor units. For example, if a component (e.g., a first control unit) for controlling the speed of the indoor fan 3 is included in the indoor unit of the air conditioner and a component (e.g.,a second control unit) for controlling the frequency of the compressor 4 is included in the outdoor unit of the air conditioner, these components (first control unit and second control unit) are collectively referred to as “control unit 2”.

[0026] As in Fig. As shown in Figure 2, the control device 2 includes a control processing device 21, a storage device 23, and a timer 22. The control processing device 21 performs processing steps such as calculations and determinations, and controls the equipment of the refrigeration cycle device 1, such as the indoor fan 3 and the compressor 4, based on the input temperature information. The storage device 23 includes a volatile storage device (not shown), such as a random access memory (RAM), capable of temporarily storing data, and a non-volatile auxiliary storage device (not shown), such as a hard disk or flash memory, capable of long-term storage. The timer 22 is controlled by, for example, a timer and counts time. The timer 22 serves to determine, etc., the control processing device 21.

[0027] The control processing device 21 may be implemented, for example, as a microcomputer including an arithmetic control processing unit such as a central processing unit (CPU). The storage device 23 contains data in which a processing operation to be executed by the control processing device 21 is programmed. The arithmetic control processing unit executes processing based on program data to perform control. Each device may be configured by dedicated equipment (hardware).

[0028] The control device 2 controls the speed of the indoor fan 3 and the frequency of the compressor 4. When calculating the indoor fan speed of the indoor fan 3, the control device 2 refers to a room temperature detected by the room temperature sensor 11 and a room temperature set by a user of the refrigeration cycle device 1, and uses a predetermined control gain. When calculating the frequency of the compressor 4, the control device 2 refers to a temperature of the evaporator 5 and a target value previously stored in the storage device 23, and uses a predetermined control gain.

[0029] The operation of the refrigeration cycle device 1 is described below with reference to Fig. 1 described.

[0030] A gaseous refrigerant, which is brought into a state of high temperature and high pressure by the compression by the compressor 4, exits the outlet of the compressor 4 and flows into the condenser 7. The gaseous refrigerant flowing into the condenser 7 releases heat, is liquefied in the condenser 7 under high pressure, and flows out of the condenser 7. The liquid refrigerant that has exited the condenser 7 is decompressed into a low-temperature two-phase state by the electronic expansion valve 6 and flows into the evaporator 5. The low-temperature two-phase refrigerant that has flowed into the evaporator 5 absorbs heat, is evaporated in the evaporator 5 under low pressure, and flows out of the evaporator 5. The refrigerant flowing out of the evaporator 5 is sucked into the compressor 4 and recompressed.By repeating such a process, a cooling cycle of the refrigeration cycle device 1 is achieved.

[0031] The dehumidification operation is described below with reference to Fig. 1. The indoor fan 3 blows indoor air into a piping through which the low-temperature two-phase refrigerant flowed into the evaporator 5 flows, so that the incoming low-temperature two-phase refrigerant absorbs heat from the temperature of the indoor air to be vaporized under low pressure. When the temperature of the piping through which the low-temperature two-phase refrigerant flowed into the evaporator 5 flows is lower than the dew point of the indoor air, the moisture contained in the air blown in by the indoor fan 3 condenses, and the condensed moisture is discharged to the outside through a drain (not shown). In this way, the dehumidification operation of the refrigeration cycle device 1 is performed.

[0032] The Fig. The refrigerant circuit 10 shown in FIG. 1 has a minimum configuration for performing a refrigeration cycle in the refrigeration cycle device 1 according to the present disclosure. The refrigeration cycle device 1 may include a four-way valve for switching a refrigerant passage, an accumulator for suppressing the suction of a liquid refrigerant into the compressor 4, and / or other devices as needed. In the present disclosure, heat exchange occurs between air and a refrigerant in the condenser 7 and the evaporator 5, but the heat exchange does not necessarily occur between a refrigerant and air. For example, heat exchange may occur between a refrigerant and water.

[0033] Fig. 3 is a functional block diagram showing the functions of the Fig. 1 shows the control device 2.

[0034] As in Fig. 3, the control device 2 comprises a room temperature control unit 211 and an evaporation temperature control unit 212.

[0035] The room temperature control unit 211 controls the room temperature so that the room temperature approaches a predetermined room temperature (also referred to as a "set room temperature"). The room temperature control unit 211 includes, for example, a control unit that calculates a rotation speed of the indoor fan 3 at which the room temperature should approach the set room temperature. The indoor fan rotation speed of the indoor fan 3 is also referred to as the "indoor unit fan speed." The control unit of the room temperature control unit 211 includes at least one integrator. The term "integrator" here refers to an integrator that performs an integral operation.

[0036] The control unit of the room temperature control unit 211 is, for example, a feedback control unit. In the Fig. In the example shown in Figure 3, the design behavior of the feedback control unit of the room temperature control unit 211 is a first-order delay system. Specifically, in a case where a control target model for the controller design is a first-order delay system or a dead time + first-order delay system, the room temperature control unit 211 is formed by a PI controller. In this case, as shown in equation (1), a deviation between a predetermined set room temperature Tr set [degC] and a room temperature Tr [degC] detected by the room temperature sensor 11 (ie ΔTr = Tr set - Tr) is input to the PI controller, and the PI controller calculates a speed of the indoor fan at which the room temperature is caused to follow the set room temperature and controls the speed of the indoor fan to an arithmetic value U ifan[rpm]. In this application, the "PI controller" refers to a controller consisting of a P controller and an I controller, the "P controller" refers to a proportional element, and the "I controller" refers to an integrating element. Uifan=KPRΔTr+KIr∫ΔTrdt

[0037] In equation (1) K pr a proportional gain for the PI controller and K lr An integral gain for the PI controller. The control performed by the room temperature control unit 211 can be a PID control based on the design behavior or a control target model for the design. If there is no deviation from the set room temperature and only simple control is required, the control by the room temperature control unit 211 can be performed as an I control.

[0038] These control gains, such as the proportional gain and the integral gain, are designed using a method such as the pole assignment method, the CHR method, or the Ziegler-Nichols (ZN) method. The room temperature control unit 211 must be discretized during implementation using a microcomputer, a DSP, or the like, where the calculation method can be position- or speed-based.

[0039] The evaporation temperature control unit 212 controls the evaporation temperature so that the evaporation temperature approaches a predetermined refrigerant temperature (also referred to as a "target evaporation temperature"). The evaporation temperature control unit 212 includes, for example, a control unit that calculates a frequency of the compressor 4 at which the evaporation temperature is caused to approach the target evaporation temperature. The frequency of the compressor 4 is also referred to as a "compressor frequency." The control unit of the evaporation temperature control unit 212 includes at least one integrator.

[0040] The control unit of the evaporation temperature control unit 212 is, for example, a feedback control unit. The feedback control unit of the evaporation temperature control unit 212 ensures that the evaporation temperature approaches the target value of the evaporation temperature. For example, the design behavior of the feedback control unit of the Fig. 3, the evaporation temperature control unit 212 comprises a first-order delay system. Specifically, in the case where the control target model for the controller design is a first-order delay system or a dead time + first-order delay system, the evaporation temperature control unit 212 is formed by a PI controller. In this case, as shown in equation (2), a deviation between a predetermined evaporation temperature target value ET tg [degC] and an evaporation temperature ET [degC] detected by the evaporation temperature sensor 12 (ie ΔET = ET tgt- ET) is input into the PI controller, and the PI controller calculates a frequency of the compressor at which the evaporation temperature is caused to follow the target value of the evaporation temperature and controls the compressor frequency to an arithmetic value U comp [Hz]. Ucomp=KpeΔET+KIe∫ΔETdt

[0041] In equation (2) K pe a proportional gain for the PL controller and K le an integral gain for the PI controller. The control performed by the evaporation temperature control unit 212 can be PID control, which depends on the design behavior or a control target model for the design. If there is no deviation from the target evaporation temperature and only simple control is required, the control by the room temperature control unit 211 can be performed as I control.

[0042] These control gains, such as the proportional gain and the integral gain, are determined by a method such as the pole assignment method, the CHR method, or the ZN method. The evaporation temperature control unit 212 must be discretized during implementation using a microcomputer, a DSP, or similar devices, but the calculation method can be position- or speed-based. For example, the target evaporation temperature can be a fixed value of 0 [degC] or more, it can vary according to the set room temperature, or it can vary according to a difference between the room temperature and the set room temperature.

[0043] The control unit of the room temperature control unit 211 and the evaporation temperature control unit 212 does not necessarily have to be a PI controller. For example, the control unit of the room temperature control unit 211 and the evaporation temperature control unit 212 can be a control unit (e.g., a feedback control unit) that includes at least one integrator, such as an I controller or a PID controller.

[0044] The control unit of each of the room temperature control unit 211 and the evaporation temperature control unit 212 may have an anti-reset windup function to prevent a windup phenomenon. The anti-reset windup function is the function that stops the operation of an integrator when it is not selected by a selector, allowing processes such as maintenance or automatic adjustment to be performed at a value immediately before the limit. The control unit of the room temperature control unit 211 and the evaporation temperature control unit 212 may each be constituted by a speed-based PI controller.

[0045] As described above, the room temperature control unit 211 and the evaporation temperature control unit 212 operate independently of each other. Consequently, the indoor temperature is individually controlled by the indoor fan 3, and the evaporation temperature is individually controlled by the compressor 4.

[0046] Fig. 4 is a flowchart schematically showing an example of a control method for controlling a room temperature and an evaporating temperature in the refrigeration cycle device 1.

[0047] As described above, the control method for controlling the room temperature and the evaporation temperature includes the following steps.

[0048] In particular, the control method for controlling the room temperature and the evaporation temperature includes calculating an indoor fan speed at which the room temperature is caused to approach a set room temperature (step S1) and calculating a compressor frequency at which the evaporation temperature is caused to approach a target evaporation temperature (step S2). Depending on the indoor fan speed and compressor frequency calculated in these steps, the control unit 2 controls the indoor fan 3 and the compressor 4 (step S3). Consequently, the room temperature is individually controlled by the indoor fan 3 and the evaporation temperature is individually controlled by the compressor 4. The order of steps S1 and S2 is not limited to the Fig. 4. The method in step S1 and the method in step S2 can run simultaneously. <Vorteile der ersten Ausführungsform>

[0049] In the first embodiment, the indoor fan speed is controlled to maintain a comfortable room temperature, and the compressor frequency is controlled to an evaporation temperature to maintain a comfortable room humidity. That is, the room temperature is individually controlled by the indoor fan 3, and the evaporation temperature is individually controlled by the compressor 4. Accordingly, the room temperature and humidity can be individually controlled, so that a comfortable room temperature and humidity can be maintained even during medium or high-load ventilation operation.

[0050] Furthermore, according to the first embodiment, a latent heat process (ie, dehumidification) can be further improved by increasing the air conditioning capacity itself as well as the ratio between latent heat and sensible heat. First variant

[0051] Fig. 5 is a functional block diagram showing another example of the control device 2.

[0052] A control device 2 according to a first variant differs from that shown in the Fig. 1 to 3 in that it further includes a compressor smoothness control unit 219. The compressor smoothness control unit 219 performs control to reduce the influence of the evaporation temperature by the indoor fan 3 via a frequency of the compressor in advance. Specifically, the compressor smoothness control unit 219 calculates which increases the frequency of the compressor 4 when the indoor fan speed of the indoor fan 3 increases and which decreases the compressor frequency of the compressor 4 when the indoor fan speed of the indoor fan 3 decreases.

[0053] The compressor 219 trouble-free control unit can, for example, be designed with a transfer function from the indoor fan speed to the evaporating temperature and a transfer function from the compressor frequency to the evaporating temperature. Assume that the transfer function from the compressor frequency to the evaporating temperature is a process gain K ETcomp a steady state response and the transfer function from the indoor fan speed to the evaporation temperature is a process gain K ETifan of a stationary behavior, then an arithmetic value U c _ comp expressed by equation (3): Uc_comp=−Uifan∗KETifanKETcomp=−Uifan∗Kcomp

[0054] In equation (3) U ifan the indoor fan speed itself or a variation ΔU ifanthe indoor fan speed. It is sufficient for an arithmetic operator of a speed change to be a value corresponding to the speed change, such as a calculation using a difference from the previous value or a calculation using a low-pass filter. In equation (3), the characteristics (i.e., the transfer functions) of both systems are process gains of the steady-state behavior, but a model that considers the transition of, for example, a first-order delay system can further reduce the influence of disturbances. The transfer functions are not limited to this example and only need to include one example that reduces disturbances.

[0055] In the first variant, the influence on the room temperature caused by the frequency of the compressor can be avoided. Second variant

[0056] Fig. 6 is a functional block diagram showing another example of the control device 2.

[0057] A control device 2 according to a second variant differs from that shown in the Fig. 1 to 3 in that it also includes an indoor fan interference control unit 220. Generally, when an indoor fan and a compressor are controlled individually, the response may deteriorate due to interference between the operation of the indoor fan and the compressor. Against this background, the indoor fan interference control unit 220 of the second variant controls the compressor 4's influence on the room temperature in advance via the indoor fan speed. Specifically, the indoor fan interference control unit 220 calculates an indoor fan speed of the indoor fan 3 that decreases the indoor fan speed of the indoor fan 3 when the frequency of the compressor 4 increases and increases the indoor fan speed of the indoor fan 3 when the frequency of the compressor 4 decreases.

[0058] The indoor fan smoothness control unit 220 can be designed, for example, using a transfer function from the compressor frequency to the room temperature and a transfer function from the indoor fan speed to the room temperature. Assume that the transfer function from the compressor frequency to the room temperature is a process gain K Trcomp of a stationary behavior and the transfer function from the indoor fan speed to the room temperature is a process gain K Trifan of a stationary behavior, then an arithmetic value U c_ifan expressed by equation (4): Uc_ifan=−Ucomp∗KTrcompKTrifan=−Ucomp∗Kifan

[0059] In equation (4) U comp a frequency of the compressor itself or a variation ΔU compthe frequency of the compressor. It is sufficient for an arithmetic operator of a speed or rpm change to be a value corresponding to the speed change, such as a calculation using a difference from the previous value or a calculation using a low-pass filter. In equation (4), the characteristics (i.e., the transfer functions) of both systems are process gains of the steady-state behavior, but a model that accounts for the transition of, for example, a first-order delay system can further reduce the influence of disturbances. The transfer functions are not limited to this example and only need to include one example that reduces disturbances or influences.

[0060] In the second variant, the influence of the compressor frequency on the room temperature can be avoided. Third variant

[0061] Fig. 7 is a functional block diagram showing another example of the control device 2.

[0062] A control device 2 according to a third variant differs from that shown in the Fig. 1 to 3 in that it further includes a compressor troubleshooting control unit 219 and an indoor fan troubleshooting control unit 220. The compressor troubleshooting control unit 219 calculates a frequency of the compressor 4 by multiplying a calculation result calculated by the evaporation temperature control unit 212 by a constant. The indoor fan troubleshooting control unit 220 calculates an indoor fan speed by multiplying a calculation result calculated by the room temperature control unit 211 by a constant. Fourth variant

[0063] The Fig. The refrigeration cycle device 1 shown in Figure 1 may contain a liquid trap. This liquid trap is located at the inlet of the compressor 4 and separates a liquid refrigerant that has not evaporated in the evaporator 5. The Fig. The refrigeration cycle device 1 shown in Figure 1 may also include an injection circuit. If the outlet temperature rises too high, the injection circuit causes a low-pressure refrigerant to flow into the compressor 4 to lower the outlet temperature.

[0064] Fig. 8 is a diagram showing a comparison between the operation in a conventional refrigeration cycle device and the operation in the refrigeration cycle device 1 according to the first embodiment.

[0065] As in Fig. As shown in Figure 8, in the conventional refrigeration cycle device, when the room temperature reaches a set temperature, the dehumidification operation is switched to quickly reduce the indoor fan speed. Thus, the compressor frequency may not increase because freezing is prevented. On the other hand, in the refrigeration cycle device 1 according to the present disclosure, the performance is less likely to decrease because the indoor fan speed and the compressor frequency are individually controlled.

[0066] Fig. 9 is a diagram showing an operating range of the refrigeration cycle device 1.

[0067] As in Fig. As shown in Fig. 9, in the conventional refrigeration cycle device, the air flow rate is reduced during the dehumidification operation, so that the refrigeration cycle device can only operate in a region where the latent heat and sensible heat are low. On the other hand, the refrigeration cycle device 1 according to the present disclosure can also operate in a region where the latent heat and sensible heat are high, and does not switch between the cooling operation and the operation, so that no discontinuity occurs in the operation. In other words, the refrigeration cycle device 1 according to the present disclosure can operate from a region of conventional cooling operation and conventional dehumidification operation with a latent heat of 0 kW or more to a region of high latent heat and sensible heat. <Vorteile der Kältekreislaufeinrichtung 1>

[0068] According to the present disclosure, the room temperature control unit 211 calculates the indoor fan speed, and the evaporation temperature control unit 212 calculates the compressor frequency. Accordingly, the room temperature and the evaporation temperature can be individually controlled to appropriate values. In other words, the control target and the control unit can be controlled in a one-to-one relationship. That is, a target room temperature and a target room humidity can be individually set, so that a drop in the room temperature due to the dehumidification operation can be prevented and a comfortable room temperature and comfortable room humidity can be quickly achieved. This can expand the operating range of the refrigeration cycle device 1.

[0069] Furthermore, according to the present disclosure, the compressor 4 and the indoor fan speed can be controlled by the control unit in a feedback control / regulation manner. With this configuration, the target values ​​can be achieved quickly.

[0070] Furthermore, according to the present disclosure, since operation switching is not performed, the risk of a rise in room temperature and the return of humidity during dehumidification that occurs in operation switching can be avoided. SECOND EXAMPLE

[0071] Fig. 10 is a block diagram showing another example of the control device 2.

[0072] A control device 2 according to a second embodiment differs from that shown in the Fig. 1 to 3 in that it comprises, in addition to the room temperature control unit 211 and the evaporation temperature control unit 212, an evaporation temperature upper limit protection control unit 213, an evaporation temperature lower limit protection control unit 214, a primary indoor fan speed selection unit 215, a secondary indoor fan speed selection unit 216, a thermo-off control unit 217, and a compressor frequency selection unit 218.

[0073] The upper limit evaporation temperature protection control unit 213 includes a control unit that calculates an indoor fan speed at which the evaporation temperature is caused to follow a predetermined upper limit evaporation temperature. The upper limit evaporation temperature protection control unit 213 includes at least one integrator. In this case, the upper limit evaporation temperature protection control unit 213 is formed, for example, by a PI positioning controller. The upper limit evaporation temperature protection control unit 213 calculates the indoor fan speed U ifan[rpm], expressed by equation (5), and outputs a calculation result. The PI controller constituting the evaporation temperature upper limit protection control unit 213 receives a deviation between the predetermined evaporation temperature upper limit ETmax [degC] and an evaporation temperature ET [degC] detected by the evaporation temperature sensor 12 (ie, ΔETmax = ETmax - ET). The PI controller constituting the evaporation temperature upper limit protection control unit 213 calculates an indoor fan speed U ifan [rpm] at which the evaporating temperature is caused to follow the upper limit of the evaporating temperature and outputs a calculation result. Uifan=Kp_ETmaxΔETmax+KI_ETmax∫ΔETmaxdt

[0074] In equation (5) K p_ETmax a proportional gain for the PI control and K I_ETmaxis an integral gain for PI control. Assuming the target response is adopted as the primary delay system, the control performed by the evaporation temperature upper limit protection control unit 213 is PI control, and assuming the target response is adopted as the secondary delay system, the control performed by the evaporation temperature upper limit protection control unit 213 is PID control. These control gains can be designed using a CHR method, a ZN method, or other methods. The evaporation temperature upper limit protection control unit 213 can be formed by a rate-based PI controller.

[0075] The lower limit evaporation temperature protection control unit 214 includes a control unit that calculates an indoor fan speed at which the evaporation temperature is caused to follow a predetermined lower limit evaporation temperature. The lower limit evaporation temperature protection control unit 214 includes at least one integrator. In this case, the lower limit evaporation temperature protection control unit 214 is formed, for example, by a PI positioning controller. The lower limit evaporation temperature protection control unit 214 calculates the indoor fan speed U ifan[rpm], expressed by equation (6), and outputs a calculation result. The PI controller constituting the evaporation temperature lower limit protection control unit 214 receives a deviation between the predetermined evaporation temperature lower limit ETmin [degC] and an evaporation temperature ET [degC] detected by the evaporation temperature sensor 12 (ie, ΔETmin = ETmin - ET). The PI controller constituting the evaporation temperature lower limit protection control unit 214 calculates an indoor fan speed U ifan [rpm] at which the evaporating temperature is caused to follow the lower limit of the evaporating temperature and outputs a calculation result. Uifan=Kp_ETminΔETmin+KI_ETmin∫ΔETmint

[0076] In equation (6) K p_ETmin a proportional gain for the PI control and K p-ETminis an integral gain for PI control. Assuming the target response is a primary delay system, the control performed by the evaporation temperature lower limit protection control unit 214 is PI control, and assuming the target response is a secondary delay system, the control performed by the evaporation temperature lower limit protection control unit 214 is PID control. These control gains can be designed using a CHR method, a ZN method, or other methods. The evaporation temperature lower limit protection control unit 214 can be configured as a rate-based PI controller. For example, the evaporation temperature lower limit is 0°C or more and is lower than a target evaporation temperature.

[0077] The primary indoor fan speed selection unit 215 is formed by a selector that selects a minimum value from input values ​​(also called „ Minimum selector" or "first minimum selector"). Specifically, the primary indoor fan speed selection unit 215 selects a minimum value from an output value of the room temperature control unit 211 (i.e., calculation result output from the room temperature control unit 211) and an output value of the evaporation temperature upper limit protection control unit 213 (i.e., calculation result output from the evaporation temperature upper limit protection control unit 213), and outputs the selected minimum value as the selected value.

[0078] The secondary indoor fan speed selection unit 216 is composed of a selector that selects a maximum value from the input values ​​(also referred to as a "maximum selector"). Specifically, the secondary indoor fan speed selection unit 216 selects a maximum value from an output value of the evaporation temperature lower limit protection control unit 214 (i.e., the calculation result output by the evaporation temperature lower limit protection control unit 214) and an output value of the primary indoor fan speed selection unit 215 (i.e., the calculation result output by the primary indoor fan speed selection unit 215), and sets the indoor fan speed to this maximum value (i.e., the selected value).

[0079] The thermo-off control unit 217 contains a control unit that calculates a compressor frequency at which the room temperature follows a predetermined thermo-off temperature. The control unit of the thermo-off control unit 217 contains at least one integrator. In this case, the control unit of the thermo-off control unit 217 is formed, for example, by a PI controller. The thermo-off control unit 217 calculates a compressor frequency U comp [Hz], expressed by equation (7), and outputs a calculation result. The PI controller constituting the thermo-off control unit 217 receives a deviation between a predetermined thermo-off temperature T0 [degC] and a room temperature Tr [degC] detected by the room temperature sensor 11 (i.e., ΔT0 = T0 - Tr). The PI controller constituting the thermo-off control unit 217 calculates a frequency of the compressor U comp[Hz] at which the room temperature follows the thermo-off temperature and outputs a calculation result. Ucomp=Kp_toΔTO+KI_to∫ΔTOdt

[0080] In equation (7) K p_to a proportional gain for the PI control and K I_tois an integral gain for PI control. Assuming the target response is assumed as the primary delay system, the control by the thermo-off control unit 217 is performed as PI control, and assuming the target response is assumed as the secondary delay system, the control by the thermo-off control unit 217 is performed as PID control. These control gains can be designed using a CHR method, a ZN method, or other methods. The thermo-off control unit 217 can be formed by a speed-based PI controller. The thermo-off temperature can be set, for example, at a value 3 degrees Celsius lower than the set room temperature.

[0081] The compressor frequency selection unit 218 is constituted by a selector that selects a minimum value from the input values ​​(also referred to as a "minimum selector" or "second minimum selector"). Specifically, the compressor frequency selection unit 218 selects a minimum value from an output value of the evaporation temperature control unit 212 (i.e., the calculation result output by the evaporation temperature control unit 212) and an output value of the thermo-off control unit 217 (i.e., the calculation result output by the thermo-off control unit 217), and the frequency of the compressor is set to this minimum value (i.e., the selected value).

[0082] The control unit of each of the evaporation temperature upper limit protection control unit 213, the evaporation temperature lower limit protection control unit 214, and the thermo-off control unit 217 does not necessarily have to be the PI controller. For example, the control unit of each of the evaporation temperature upper limit protection control unit 213, the evaporation temperature lower limit protection control unit 214, and the thermo-off control unit 217 may be a control unit (e.g., a feedback controller) that includes at least one integrator, such as an I controller or a PID controller. In this application, the term "PID controller" refers to a control unit that includes a P controller, an I controller, and a D controller, and the term "D controller" refers to a derivative.

[0083] The control unit of each of the evaporation temperature upper limit protection control unit 213, the evaporation temperature lower limit protection control unit 214, and the thermal-off control unit 217 may have an anti-reset windup function to prevent a windup phenomenon. The anti-reset windup function is the function of stopping the integrator's operation in a case where an integrator output of a target is limited or not selected by a selector, and can perform processes such as maintenance, automatic adjustment, etc., at a value immediately before the limitation. <Vorteile der zweiten Ausführungsform>

[0084] The second embodiment has the advantages described in the first embodiment.

[0085] According to the second embodiment, the evaporation temperature upper limit protection control unit 213 calculates an indoor fan speed, and the primary indoor fan speed selection unit 215 selects a minimum value from an output value of the room temperature control unit 211 and an output value of the evaporation temperature lower limit protection control unit 213. With this configuration, the room temperature can be controlled while simultaneously protecting an evaporation temperature upper limit to prevent damage to the refrigeration cycle device 1 (e.g., the evaporator 5).

[0086] Further, the evaporation temperature upper limit protection control unit 213 calculates an indoor fan speed, and the secondary indoor fan speed selection unit 216 selects a maximum value from an output value of the primary indoor fan speed selection unit 215 and an output value of the evaporation temperature lower limit protection control unit 214. This configuration can control the room temperature while protecting the evaporation temperature lower limit and the evaporation temperature upper limit to prevent damage to the refrigeration cycle device 1 (e.g., the evaporator 5). In other words, the evaporation temperature lower limit is controlled to a value lower than the target evaporation temperature, so that an excessive drop in the evaporation temperature due to the influence of the indoor fan 3 can be prevented.

[0087] Furthermore, the thermo-off control unit 217 calculates a frequency of the compressor, and the compressor frequency selection unit 218 selects a minimum value from an output value of the evaporation temperature control unit 212 and an output value of the thermo-off control unit 217. With this configuration, the evaporation temperature can be controlled up to the thermo-off temperature limit. This means that the dehumidification operation can be performed until the thermo-off temperature is reached. This prevents the room temperature from dropping or heating up due to the dehumidification operation, thus quickly achieving a comfortable room temperature and comfortable room humidity.

[0088] Furthermore, according to the second embodiment, a target value for the room temperature and a target value for the room humidity can be individually set, and it is possible to expand the operating range while protecting the evaporation temperature to prevent damage to the refrigeration cycle device 1 (e.g., the evaporator 5).

[0089] Furthermore, according to the second embodiment, the latent heat process (ie, dehumidification) can be further improved by increasing the air conditioning performance itself as well as the ratio between latent heat and sensible heat. THIRD EXAMPLE

[0090] Fig. 11 is a flowchart showing an example of a method for controlling a frequency of the compressor so that an evaporating temperature approaches a target evaporating temperature.

[0091] A room temperature Tr [degC] is detected by a room temperature sensor 11 (step S11). A relative humidity H [%] that does not cause discomfort is calculated, for example, by equation (8) using a discomfort index DI and a room temperature Tr [degC] detected by the room temperature sensor 11. H=100(DI−0.81Tr−46.3)0.99Tr−14.3

[0092] If the discomfort index DI is 73 or less, few people will feel uncomfortable. According to equation (9), the saturated water vapor pressure Pws [hPa] at room temperature is calculated using the room temperature Tr [degC] and the Tetens equation. In equation (9), A, m, and Tn are constants. Pws=A×10m×TrTr+Tn

[0093] Using the saturation water vapor pressure Pws [hPa], a water vapor partial pressure Pw [hPa] is calculated according to equation (10) that does not cause any discomfort: Pw=Pws×H / 100

[0094] A dew point Td [degC] of relative humidity that does not cause discomfort is calculated using Teten's equation from equation (11): Td=Tnmlog10(PwA)−1

[0095] A value obtained by equation (11) may be used as a target value for the evaporation temperature, or the value obtained by equation (11) may be corrected and used as a target value for the evaporation temperature.

[0096] The storage device 23 may store a saturated water vapor pressure table as a comfort index in advance, and a saturated water vapor pressure Pws [hPa] may be calculated from this saturated water vapor pressure table.

[0097] The refrigeration cycle device 1 may also include a room humidity sensor that measures the room humidity. If the refrigeration cycle device 1 includes a room humidity sensor, the target evaporation temperature can be corrected based on the room humidity detected by the room humidity sensor. In this method, the target evaporation temperature is determined based on the room temperature detected by the room humidity sensor 11 and a comfort index (step S12).

[0098] The control device 2 controls the frequency of the compressor so that the evaporation temperature approaches the target value of the evaporation temperature (step S13). <Vorteile der dritten Ausführungsform>

[0099] The third embodiment has the advantages described in the first embodiment.

[0100] Furthermore, according to the third embodiment, the target evaporation temperature of the evaporation temperature control unit 212 is calculated using the method described above, so that a room humidity that does not cause discomfort can be achieved at any given room temperature. Furthermore, according to the third embodiment, a room humidity that does not cause discomfort can be achieved without a room hygrometer.

[0101] If the refrigeration cycle device 1 includes a room humidity sensor, the target evaporation temperature can be corrected without excessive dehumidification.

[0102] The features of the embodiments and variants described above can be combined with each other. DESCRIPTION OF REFERENCE SYMBOLS

[0103] 1 Refrigeration cycle device, 2 Control device, 3 Indoor fan, 4 Compressor, 5 Evaporator, 6 Electronic expansion valve, 7 Condenser, 8 Outdoor fan, 9 Piping, 10 Refrigerant circuit, 11 Room temperature sensor, 12 Evaporating temperature sensor, 211 Room temperature control unit, 212 Evaporating temperature control unit, 213 Evaporating temperature upper limit protection control unit, 214 Evaporating temperature lower limit protection control unit, 215 Primary indoor fan speed selection unit, 216 Secondary indoor fan speed selection unit, 217 Thermo-off control unit, 218 Compressor frequency selection unit, 219 Compressor health control unit, 220 Indoor fan health control unit.

Claims

[1] Refrigeration cycle device, comprising: a compressor that compresses a refrigerant; a capacitor; an expansion valve; an evaporator; an indoor fan; a control device that controls a speed of the indoor fan and a frequency of the compressor; a room temperature sensor that detects a room temperature; and an evaporation temperature sensor that detects an evaporation temperature of a refrigerant in the evaporator, wherein the control device comprises a room temperature control unit having a control unit that calculates the speed of the indoor fan at which the room temperature is caused to approach a predetermined room temperature, and an evaporation temperature control unit having a control unit that calculates the frequency of the compressor at which the evaporation temperature is caused to approach a predetermined refrigerant temperature, and where the room temperature is individually controlled by the indoor fan and the evaporation temperature is individually controlled by the compressor. [2] The refrigeration cycle device according to claim 1, wherein the control device further comprises a compressor trouble-free control unit, the compressor trouble-free control unit being configured to calculate the frequency of the compressor so that the frequency of the compressor is increased in a case where the rotational speed of the indoor fan increases and the frequency of the compressor is decreased in a case where the rotational speed of the indoor fan decreases. [3] The refrigeration cycle device according to claim 1 or 2, wherein the control device further comprises an indoor fan trouble-free control unit, the indoor fan trouble-free control unit being configured to calculate the rotational speed of the indoor fan such that the rotational speed of the indoor fan is reduced when the frequency of the compressor increases, and that the rotational speed of the indoor fan is increased when the rotational speed of the indoor fan decreases. [4] Refrigeration cycle device according to one of claims 1 to 3, wherein the control device also comprises an evaporation temperature upper limit protection control unit including a control unit that calculates the indoor fan speed at which the evaporation temperature is caused to follow a predetermined evaporation temperature upper limit, and a primary indoor fan speed selection unit that selects a minimum value from an output value of the room temperature control unit and an output value of the evaporation temperature upper limit protection control unit. [5] Refrigeration cycle device according to claim 4, wherein the control device also comprises an evaporation temperature lower limit protection control unit including a control unit that calculates the indoor fan speed at which the evaporation temperature is caused to follow a predetermined evaporation temperature lower limit, and a secondary indoor fan speed selection unit that selects a maximum value from an output value of the evaporation temperature lower limit protection control unit and an output value of the primary indoor fan speed selection unit. [6] Refrigeration cycle device according to one of claims 1 to 5, wherein the control device also comprises a thermo-off control unit with a control unit that calculates the frequency of the compressor at which the room temperature is caused to follow a predetermined thermo-off temperature, and a compressor frequency selection unit that selects a minimum value from an output value of the evaporation temperature control unit and an output value of the thermo-off control unit. [7] Refrigeration cycle device according to one of claims 1 to 6, wherein the control device further includes a storage device that stores a comfort index, and the predetermined refrigerant temperature is determined based on the room temperature and the comfort index. [8] A control method in a refrigeration cycle device including a compressor that compresses a refrigerant, a condenser, an expansion valve, an evaporator, an indoor fan, a control device that controls a rotational speed of the indoor fan and a frequency of the compressor, a room temperature sensor that detects a room temperature, and an evaporation temperature sensor that detects an evaporation temperature of a refrigerant in the evaporator, the method comprising: Calculating the indoor fan speed at which the room temperature is caused to approach a predetermined room temperature; and Calculating the frequency of the compressor at which the evaporating temperature is caused to approach a given refrigerant temperature, where the room temperature is individually controlled by the indoor fan and the evaporation temperature is individually controlled by the compressor.

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