Refrigeration cycle device

Abstract

This refrigeration cycle device comprises: a refrigerant circuit including a constant-speed compressor, a condenser, an evaporator, and a pressure reducer; an air blowing fan that blows air toward the evaporator and the condenser; and a control means for controlling the air blowing fan. The control means starts operation of the air blowing fan by setting the rotation speed of the air blowing fan to a second rotation speed lower than a first rotation speed, which is a reference setting value, when the compressor and the air blowing fan are operated at the start of product operation, continues the operation of the air blowing fan at the second rotation speed until a predetermined period of time elapses, and operates the air blowing fan by changing the rotation speed of the air blowing fan from the second rotation speed to the first rotation speed after the predetermined period of time has elapsed.

Description

Technical Field

[0001] The present disclosure relates to a refrigeration cycle device.

Background Art

[0002] In a refrigeration cycle used in an air conditioner, a refrigerator, a dehumidifier, etc., during operation of the product, the refrigeration oil is maintained in the compressor to avoid shaft seizure of the compressor. In particular, immediately after the start of operation of the product, since the cycle state where the superheat of the refrigerant cannot be ensured, the risk of depletion of the refrigeration oil in the compressor increases. Patent Document 1 discloses a technique for estimating the refrigerant flow rate and, when it is higher than a preset threshold value, reducing the operating frequency of the compressor to suppress the amount of refrigeration oil discharged and prevent depletion of the refrigeration oil in the compressor.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The technique disclosed in Patent Document 1 can be applied to an inverter-type compressor, but cannot be applied to a constant-speed compressor.

[0005] The present disclosure is for solving the above problems. The object of the present disclosure is to prevent depletion of the refrigeration oil in the compressor and avoid shaft seizure of the compressor in a refrigeration cycle device equipped with a constant-speed compressor.

Means for Solving the Problems

[0006] The refrigeration cycle device according to the present disclosure includes a refrigerant circuit composed of a constant-speed compressor, a condenser, an evaporator, and a decompression device, a blower fan that sends air to the evaporator and the condenser, and control means for controlling the blower fan. When the compressor and the blower fan operate at the start of product operation, the control means sets the rotation speed of the blower fan to a second rotation speed lower than the reference set value, which is the first rotation speed, and operates the blower fan at the second rotation speed until a specified time has elapsed. After the specified time has elapsed, the rotation speed of the blower fan is changed from the second rotation speed to the first rotation speed to operate the blower fan. Start the operation of the blower fan at the first rotational speed, and continue the operation of the blower fan at the first rotational speed until the first specified time has elapsed. After the elapse of the first specified time, change the rotational speed of the blower fan to the to a second rotation speed lower than the first rotation speed change and the blower fan and operate operates the blower fan at the second rotation speed second continuously until a specified time has elapsed, and second after the specified time has elapsed, changes the rotation speed of the blower fan from the second rotation speed to the first rotation speed to operate the blower fan.

Advantages of the Invention

[0007] According to the present disclosure, in a refrigeration cycle device including a constant-speed compressor, it is possible to prevent the refrigerating machine oil in the compressor from running out and avoid shaft seizure of the compressor.

Brief Description of the Drawings

[0008]

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Modes for Carrying Out the Invention

[0009] Hereinafter, embodiments will be described with reference to the accompanying drawings. The same reference numerals in each figure indicate the same or corresponding parts. Also, in the present disclosure, duplicate descriptions will be appropriately simplified or omitted. Note that the present disclosure can include any combination of configurations that can be combined among the configurations described in the following embodiments.

[0010] Embodiment 1. FIG. 1 is a schematic diagram showing the configuration of the refrigeration cycle device according to Embodiment 1. FIG. 2 is a block diagram showing the control system of the refrigeration cycle device according to Embodiment 1.

[0011] The refrigeration cycle device according to the present embodiment includes a refrigerant circuit in which a refrigerant circulates. As shown in FIG. 1, the refrigerant circuit is composed of a compressor 1, a condenser 2, an evaporator 4, and a decompression device 3.

[0012] The compressor 1 functions as a means for compressing the refrigerant in the refrigerant circuit. Generally, there are an inverter type and a constant speed type compressors, but the compressor 1 in the present disclosure is of the constant speed type.

[0013] The condenser 2 and the evaporator 4 are heat exchangers that perform heat exchange between the refrigerant circulating in the refrigerant circuit and air. As shown in FIG. 1, the refrigeration cycle apparatus according to the present embodiment includes a blower fan 5 as means for sending air to the condenser 2 and the evaporator 4. Although only one blower fan 5 is illustrated in FIG. 1, a plurality of blower fans 5 may be provided. The refrigeration cycle apparatus may include blower fans corresponding to the condenser 2 and the evaporator 4, respectively.

[0014] The pressure reducing device 3 applies a pressure loss to the refrigerant circulating in the refrigerant circuit and functions as means for ensuring the degree of subcooling and the degree of superheat in the refrigeration cycle. As the pressure reducing device 3, for example, a capillary tube with a fixed Cv value or an electronic expansion valve capable of varying the Cv value can be used.

[0015] The condenser 2 condenses the high-pressure refrigerant compressed by the compressor 1. The pressure reducing device 3 decompresses and expands the high-pressure refrigerant that has passed through the condenser 2. The evaporator 4 evaporates the low-pressure refrigerant decompressed by the pressure reducing device 3. The refrigeration cycle apparatus according to the present embodiment may be used for the purpose of heating air by the condenser 2 or for the purpose of cooling air by the evaporator 4. The refrigeration cycle apparatus according to the present embodiment can be used, for example, in an air conditioner, a dehumidifier, or a refrigerator.

[0016] As shown in FIG. 2, the refrigeration cycle apparatus according to the present embodiment includes a control device 6 as control means for controlling the operation of the equipment. The control device 6 controls the operation of the blower fan 5. Note that, as shown in FIG. 2, the control device 6 may also control the operation of the compressor 1.

[0017] FIG. 3 is a diagram for explaining the operation of the refrigeration cycle device according to Embodiment 1. FIG. 4 is a control flowchart of the refrigeration cycle device according to Embodiment 1. In FIG. 3, the horizontal axis represents the elapsed time since the start of the product operation. Also, in FIG. 3, the vertical axis represents the rotation speed of the blower fan 5 and the operating state of the compressor 1. With reference to FIGS. 3 and 4, the characteristics of the operation of the refrigeration cycle device according to the present embodiment will be described.

[0018] When the compressor 1 and the blower fan 5 start operating at the start of the product operation (step S001), the control device 6 sets the rotation speed of the blower fan 5 to a second rotation speed lower than the first rotation speed, which is the reference set value, and starts the operation of the blower fan 5 (step S002). The operation of the blower fan 5 at this second rotation speed is continued until a specified time X minutes have elapsed since the start of the operation (step S003). After the elapse of the specified time X minutes, the rotation speed of the blower fan 5 is changed from the second rotation speed to the first rotation speed, which is the reference set value, and the blower fan 5 is shifted to the normal operation state (step S004).

[0019] FIG. 5 is a Mollier diagram of the refrigeration cycle device according to Embodiment 1. With reference to FIG. 5 and the mathematical formulas, the effect of operating the blower fan 5 at the second rotation speed lower than the above-described first rotation speed will be described. Using the symbols described in FIG. 5, the equations representing the refrigeration cycle are summarized in the following equations (1), (2), and (3).

[0020] TIFF0007683823000001.tif6150 TIFF0007683823000002.tif6150 TIFF0007683823000003.tif10150

[0021] The above equations (1), (2), and (3) can be transformed into the following equation (4) in form.

[0022] TIFF0007683823000004.tif10150

[0023] From Equation (4), it can be confirmed that when the adiabatic efficiency ηc of the compressor increases, the enthalpy h1’ at the compressor discharge decreases. Conversely, when the adiabatic efficiency ηc of the compressor decreases, the enthalpy h1’ at the compressor discharge increases. When the enthalpy h1’ at the compressor discharge increases, the superheat at the compressor discharge increases, and the amount of refrigerant oil flowing out of the compressor 1 decreases.

[0024] When the air volume supplied to the evaporator 4 by the blower fan 5 decreases, the suction pressure of the compressor decreases, and the suction refrigerant density of the compressor decreases. When the suction refrigerant density of the compressor decreases, the suction entropy of the compressor decreases, leading to a decrease in the adiabatic efficiency ηc of the compressor. By reducing the rotational speed of the blower fan 5, the air volume of the blower fan 5 can be decreased, the enthalpy h1’ at the compressor discharge can be increased, and by increasing the superheat at the compressor discharge, the amount of refrigerant oil flowing out of the compressor 1 can be decreased.

[0025] As described above, according to the present embodiment, by reducing the rotational speed of the blower fan 5, the time required to ensure the superheat at the compressor discharge can be reduced, and the depletion of the refrigerant oil in the compressor 1 can be prevented. According to the present embodiment, by controlling the blower fan 5, shaft seizure in the constant-speed compressor 1 can be avoided without adding components.

[0026] The second rotational speed is set as a rotational speed that is relatively lower than the first rotational speed, which is a reference set value set as the rotational speed during normal operation of the blower fan 5. For example, it is desirable that the second rotational speed be set within the range of 70% to 80% of the first rotational speed.

[0027] As described above, in the present embodiment, as a means for ensuring the compressor discharge superheat, control is performed to set the rotational speed of the blower fan 5 to the second rotational speed. By changing the rotational speed of the blower fan 5, the refrigeration cycle becomes a transient state, and it takes time to ensure the compressor discharge superheat. Therefore, the operation time of the blower fan 5 at the second rotational speed is set as a specified time X minutes. Since the specified time X minutes is affected by the state of the refrigeration cycle, the amount of refrigerant enclosed, the amount of refrigerating machine oil enclosed, etc., it cannot be specified as one value. However, as an example, it is desirable that the specified time X minutes be set as a time within the range of 10 minutes to 20 minutes.

[0028] Further, as shown in FIGS. 1 and 2, the refrigeration cycle device according to the present embodiment may include an ambient temperature detection unit 10. The ambient temperature detection unit 10 detects the dry bulb temperature of the air sucked by the blower fan 5.

[0029] The risk of refrigerating machine oil flowing out from the compressor 1 increases as the ambient temperature decreases. This is because in the refrigeration cycle, the lower the ambient temperature, the more likely the refrigerant is to accumulate in a liquid phase state in the compressor 1 and each heat exchanger. When the refrigerant in the liquid phase state circulates at the start of operation, the refrigerating machine oil is likely to flow out from the compressor 1. Therefore, in the present embodiment, it may be determined whether to enable control to change the rotational speed of the blower fan 5 according to the temperature detected by the ambient temperature detection unit 10. For example, when the temperature detected by the ambient temperature detection unit 10 is lower than a threshold value, control may be performed to set the rotational speed of the blower fan 5 to the second rotational speed.

[0030] Further, FIG. 6 is a diagram for explaining the operation of the refrigeration cycle device according to the first modification of Embodiment 1. FIG. 7 is a control flowchart of the refrigeration cycle device according to the first modification of Embodiment 1. In FIG. 6, the horizontal axis represents the elapsed time from the start of product operation. In FIG. 6, the vertical axis represents the rotational speed of the blower fan 5 and the operating state of the compressor 1. With reference to FIGS. 6 and 7, a first modification of the refrigeration cycle device according to the present embodiment will be described.

[0031] In this first modification example, when the compressor 1 and the blower fan 5 start operating at the start of product operation (step S101), the control device 6 starts the operation of the blower fan 5 by setting it to the first rotational speed which is the reference set value (step S102). The operation of the blower fan 5 at the first rotational speed which is the reference set value is continued until a specified time Y minutes have elapsed since the start of operation (step S103). As shown in FIG. 6, the specified time Y minutes is set to be shorter than the specified time X minutes.

[0032] After the process of step S103, it is determined whether the specified time X minutes have elapsed since the start of operation (step S104). If the specified time X minutes have not elapsed since the start of operation, it is determined whether the rotational speed of the current blower fan 5 is equal to or higher than the second rotational speed (step S105). In step S105, if the rotational speed of the current blower fan 5 is equal to or higher than the second rotational speed, the rotational speed of the blower fan 5 is set to the second rotational speed (step S106), and the operation of the blower fan 5 at the second rotational speed is maintained until the specified time X minutes have elapsed since the start of operation. In step S105, if the rotational speed of the current blower fan 5 is less than the second rotational speed, the control for changing the rotational speed of the blower fan 5 is terminated and the operation shifts to normal operation (step S107).

[0033] If the specified time X minutes have elapsed since the start of operation, it is determined whether the rotational speed of the current blower fan 5 is less than the reference set value (step S108). If the rotational speed of the current blower fan 5 is less than the reference set value, the rotational speed of the blower fan 5 is changed to the reference set value (step S109), and the operation shifts to normal operation (step S107). In step S108, if the rotational speed of the current blower fan 5 is equal to or higher than the reference set value, the control for changing the rotational speed of the blower fan 5 is terminated and the operation shifts to normal operation (step S107).

[0034] Thus, in the first modification example, when starting the operation of the compressor 1 and the blower fan 5 at the start of product operation, the rotation speed of the blower fan 5 is set to the reference set value instead of the second rotation speed, and is changed to the second rotation speed after a specified time Y minutes. The control of this first modification example aims to avoid the risk that the user has doubts about the product in which the blower fan 5 starts operating at the second rotation speed which is not the reference set value.

[0035] Also, FIGS. 8 and 9 are diagrams for explaining the operation of the refrigeration cycle device according to the second modification example of Embodiment 1. FIG. 10 is a control flowchart of the refrigeration cycle device according to the second modification example of Embodiment 1. In FIGS. 8 and 9, the horizontal axis represents the elapsed time since the start of product operation. In FIGS. 8 and 9, the vertical axis represents the rotation speed of the blower fan 5 and the operating state of the compressor 1. With reference to FIGS. 8, 9, and 10, the second modification example of the refrigeration cycle device according to the present embodiment will be described.

[0036] In this second modification example, when the compressor 1 and the blower fan 5 start operating at the start of product operation (step S201), the control device 6 sets the blower fan 5 to the first rotation speed which is the reference set value and starts the operation of the blower fan 5 (step S202). The operation of the blower fan 5 at the first rotation speed which is the reference set value is continued until a specified time Y minutes have elapsed since the start of operation (step S203).

[0037] After the process of step S203, it is determined whether a specified time X minutes have elapsed since the start of operation (step S204). If the specified time X minutes have not elapsed since the start of operation, it is determined whether the current rotation speed of the blower fan 5 is equal to or higher than the second rotation speed (step S205). In step S205, if the current rotation speed of the blower fan 5 is equal to or higher than the second rotation speed, the rotation speed of the blower fan 5 is decreased by ΔR (step S206). After the rotation speed of the blower fan 5 is decreased by ΔR, if a specified time Z minutes have elapsed (step S207), the process returns to the process of step S204. In step S205, if the current rotation speed of the blower fan 5 is less than the second rotation speed, the control for changing the rotation speed of the blower fan 5 is terminated and the normal operation is entered (step S208).

[0038] When the specified time X minutes have elapsed since the start of operation, it is determined whether the rotation speed of the current blower fan 5 is less than the reference set value (step S209). If the rotation speed of the current blower fan 5 is less than the reference set value, the rotation speed of the blower fan 5 is increased by ΔR (step S210). After increasing the rotation speed of the blower fan 5 by ΔR, when the specified time Z minutes have elapsed (step S211), the process returns to the process of step S209. In step S209, if the rotation speed of the current blower fan 5 is equal to or greater than the reference set value, the control to change the rotation speed of the blower fan 5 is terminated and the operation shifts to the normal operation (step S208).

[0039] As described above, in the second modification, when changing the rotation speed of the blower fan 5 according to the determination results of steps S205 and S209, the rotation speed is relatively changed instead of changing the absolute value of the rotation speed. According to the second modification, by reducing the change width of the rotation speed of the blower fan 5, the time during which the refrigeration cycle is in the transient state can be reduced, and the risk of the refrigerant oil coming out of the compressor 1 can be suppressed.

[0040] FIG. 11 is a diagram showing an example of a configuration for realizing the functions of the control device 6 in the first embodiment. The functions of the control device 6 are realized by, for example, a processing circuit. The processing circuit may be dedicated hardware 140. The processing circuit may include a processor 141 and a memory 142. A part of the processing circuit may be formed as dedicated hardware 140, and the processing circuit may further include a processor 141 and a memory 142. In the example shown in FIG. 11, a part of the processing circuit is formed as dedicated hardware 140. Also, in the example shown in FIG. 4, the processing circuit further includes a processor 141 and a memory 142.

[0041] Examples of the processing circuit in which a part is at least one piece of dedicated hardware 140 include a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC, an FPGA, or a combination thereof.

[0042] When the processing circuit includes at least one processor 141 and at least one memory 142, the functions of the control device 6 are realized by software, firmware, or a combination of software and firmware.

[0043] Software and firmware are described as programs and stored in the memory 142. The processor 141 realizes the functions of each part by reading and executing the programs stored in the memory 142. The processor 141 is also referred to as a CPU (Central Processing Unit), a central processing unit, a processing unit, an arithmetic unit, a microprocessor, a microcomputer, or a DSP. The memory 142 includes, for example, non-volatile or volatile semiconductor memories such as RAM, ROM, flash memory, EPROM, and EEPROM, or magnetic disks, flexible disks, optical disks, compact disks, mini disks, and DVDs.

[0044] In this way, the processing circuit can realize the functions of the control device 6 by hardware, software, firmware, or a combination thereof.

Industrial Applicability

[0045] The refrigeration cycle device according to the present disclosure can be used in devices such as air conditioners, dehumidifiers, and refrigerators.

Description of Reference Numerals

[0046] 1 Compressor, 2 Condenser, 3 Pressure reducing device, 4 Evaporator, 5 Blower fan, 6 Control device, 10 Ambient temperature detection unit, 140 Dedicated hardware, 141 Processor, 142 Memory

Claims

【Claim 1】 A refrigerant circuit composed of a constant-speed compressor, a condenser, an evaporator, and a pressure-reducing device, a blower fan that sends air to the evaporator and the condenser, control means for controlling the blower fan, and comprising, when the compressor and the blower fan operate at the start of product operation, the control means starts the operation of the blower fan at a first rotational speed which is a reference set value, continues the operation of the blower fan at the first rotational speed until a first specified time elapses, changes the rotational speed of the blower fan to a second rotational speed lower than the first rotational speed after the elapse of the first specified time and operates the blower fan, continues the operation of the blower fan at the second rotational speed until a second specified time longer than the first specified time elapses, and after the elapse of the second specified time, changes the rotational speed of the blower fan from the second rotational speed to the first rotational speed and operates the blower fan. A refrigeration cycle apparatus.

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