Refrigeration Cycle Equipment

Abstract

To provide a refrigeration cycle device of a refrigerator or the like, which can maximize refrigeration capacity by controlling a refrigerant circulation amount from a refrigerant temperature difference.SOLUTION: A refrigeration cycle device includes a compressor 11, a condenser 12, throttle means 15, an evaporator 16, and a plurality of temperature sensors including an upstream temperature sensor 21 and a downstream temperature sensor 22 detecting a temperature of a refrigerant pipe between the condenser 12 and the throttle means 15. A refrigerant circulation amount, for example, rotation speed of a cooling fan 45 is controlled so that a difference in temperatures detected by the upstream temperature sensor 21 and the downstream temperature sensor 22 comes closer to a set temperature difference. Thereby, refrigeration capacity is maximized and energy saving performance is enhanced.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a refrigeration cycle device, such as a refrigerator, that controls the refrigeration cycle using the temperature difference between two points on a refrigerant pipe. [Background technology]

[0002] 2. Description of the Related Art Conventionally, in a refrigerator, which is one type of refrigeration cycle device, the rotation speed of a compressor and the rotation speed of a cooling fan are controlled based on the difference between the internal temperature of a storage compartment and a set temperature (see, for example, Patent Document 1).

[0003] FIG. 6 is a diagram showing a method for controlling a compressor and a cooling fan of a conventional refrigeration cycle described in Patent Document 1. In FIG.

[0004] 6, an internal temperature detection circuit 151 detects the internal temperature in the storage compartment by an internal temperature sensor 150 installed in the storage compartment, and outputs the temperature data to a control means 152. The control means 152 determines the rotation speed of the compressor 141 and the rotation speed of the cooling fan 142 based on the difference between the temperature data of the storage compartment and a set temperature, and outputs a corresponding control command signal to a compressor drive circuit 153 and a cooling fan drive circuit 154 to control the rotation speed of the compressor 141 and the rotation speed of the cooling fan 142. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 1-33485 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the conventional configuration, the rotation speed of the compressor and the cooling fan is controlled based on the difference between the air temperature inside the refrigerator and the set temperature, so the cooling efficiency of the refrigerant cannot be taken into consideration. As a result, there is a problem that the cooling efficiency of the refrigerant may decrease depending on the usage environment and usage method, such as fluctuations in the ambient temperature of the refrigerator and the amount of storage space inside the refrigerator, and the intrusion of outside air when the door is opened and closed.

[0007] The present invention has been made to solve the above-mentioned problems in the conventional art, and has an object to provide a refrigeration cycle device that improves the cooling efficiency of a refrigerant. [Means for solving the problem]

[0008] In order to solve the above-mentioned problems in the conventional technology, the refrigeration cycle device of the present invention is a refrigeration cycle device having at least a compressor, a condenser, a throttling means, and an evaporator, and is characterized in that it is equipped with a plurality of temperature sensors that detect the temperature of the refrigerant between the condenser and the throttling means, and is equipped with a refrigerant circulation volume control means that controls the refrigerant circulation volume in accordance with the temperature difference detected by the temperature sensors. Effect of the Invention

[0009] The refrigeration cycle device of the present invention can increase the cooling efficiency of the refrigerant and improve energy saving. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a front view of a refrigerator as a refrigeration cycle device according to a first embodiment. [Diagram 2] FIG. 1 is a vertical cross-sectional view of a refrigerator according to a first embodiment. [Diagram 3] Cycle configuration diagram of a refrigerator according to the first embodiment [Figure 4] FIG. 1 is a diagram showing a method for controlling a cooling fan of a refrigeration cycle in the first embodiment. [Diagram 5] FIG. 13 is a diagram showing a correlation between the output of a refrigerant control sensor and the amount of refrigerant circulating in the refrigeration cycle in the first embodiment. [Figure 6] A diagram showing a conventional method for controlling the cooling fan of a refrigeration cycle DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The first invention is a refrigeration cycle device having at least a compressor, a condenser, a throttling means, and an evaporator, characterized in that the refrigeration cycle device is equipped with a plurality of temperature sensors that detect the temperature of the refrigerant between the condenser and the throttling means, and is equipped with a refrigerant circulation volume control means that controls the refrigerant circulation volume in accordance with the temperature difference detected by the temperature sensors.

[0012] This makes it possible to estimate the dryness fraction of the refrigerant at the condenser outlet from the detected temperature difference in the refrigerant piping at the condenser outlet, and by controlling the amount of refrigerant circulation so that the detected temperature difference approaches the set temperature difference, the dryness fraction of the refrigerant at the condenser outlet can approach zero. This increases the cooling efficiency of the refrigeration system, maximizing the refrigeration capacity and improving energy savings.

[0013] A second invention is a refrigeration cycle device described in the first invention, characterized in that the refrigerant circulation amount control means controls the rotation speed of a cooling fan that circulates the cold air generated by the evaporator inside the storage compartment.

[0014] This allows the rotation speed of the cooling fan to be controlled so that the dryness of the refrigerant at the condenser outlet approaches zero, thereby increasing the cooling efficiency of the refrigeration system, maximizing the refrigeration capacity and improving energy conservation.

[0015] A third invention is a refrigeration cycle device described in the first invention, characterized in that the refrigerant circulation amount control means controls the rotation speed of a condenser fan provided to promote condensation of the refrigerant in the condenser.

[0016] This allows the rotation speed of the condenser fan to be controlled so that the dryness of the refrigerant at the condenser outlet approaches zero, thereby increasing the cooling efficiency of the refrigeration system, maximizing the refrigeration capacity, and improving energy conservation.

[0017] A fourth invention is the refrigeration cycle apparatus according to the first invention, characterized in that the refrigerant circulation amount control means controls the rotation speed of the compressor.

[0018] This allows the rotation speed of the compressor to be controlled so that the dryness of the refrigerant at the condenser outlet approaches zero, thereby increasing the cooling efficiency of the refrigeration system, maximizing the refrigeration capacity and improving energy conservation.

[0019] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiment.

[0020] (Embodiment 1) Hereinafter, a refrigerator will be described as an embodiment of the refrigeration cycle device with reference to Figs. 1 to 5.

[0021] Fig. 1 is a front view of a refrigerator as a refrigeration cycle device according to an embodiment of the present invention, Fig. 2 is a vertical sectional view of the refrigerator according to embodiment 1, and Fig. 3 is a cycle configuration diagram of the refrigerator according to embodiment 1. Fig. 4 is a diagram showing a method of controlling a cooling fan of a refrigeration cycle, and Fig. 5 is a diagram showing a correlation between an output of a refrigerant control sensor of the refrigeration cycle and a refrigerant circulation amount.

[0022] As shown in Fig. 1 to Fig. 3, this refrigerator includes a heat-insulating refrigerator body 30 including a metal (e.g., iron plate) outer box that opens forward, a hard resin (e.g., ABS) inner box, and a heat insulating material such as hard urethane foam that is foam-filled between the outer box and the inner box. Inside the refrigerator body 30, there are provided a refrigerator compartment 31, an upper freezer compartment 32 below the refrigerator compartment 31 and an ice-making compartment 33 arranged side by side thereto, a lower freezer compartment 34 below the upper freezer compartment 32 and the ice-making compartment 33 arranged side by side thereto, and a vegetable compartment 35 below the lower freezer compartment 34. The front of the refrigerator compartment 31 is closed by, for example, a double-door door that can be opened and closed freely, and the front parts of the upper freezer compartment 32, the ice-making compartment 33, the lower freezer compartment 34, and the vegetable compartment 35 are closed by drawer-type doors that can be opened and closed freely.

[0023] The refrigerator compartment 31 is normally set at 1 to 5°C, the lowest temperature at which food will not freeze, for refrigerated storage. The vegetable compartment 35 is set at 2 to 7°C, which is the same as or slightly higher than the refrigerator compartment 31, and the low temperature makes it possible to maintain the freshness of leafy vegetables for a long period of time. The upper freezer compartment 32 and the lower freezer compartment 35 are normally set at -22 to -18°C for frozen storage, but may be set at a lower temperature, for example, -30 to -25°C, to improve the frozen storage condition.

[0024] In addition, the upper freezer compartment 32 may be a switchable compartment in which a temperature range can be selected from a refrigerated temperature range to a freezer temperature range by using a damper mechanism or the like.

[0025] The refrigerator body 30 includes the refrigeration chamber 31, the upper freezer chamber 32, the ice-making chamber 33, and the lower freezer chamber 34. A refrigeration system 10 is provided to cool the vegetable compartment 35, and a variable capacity compressor 11 that compresses the refrigerant of the refrigeration system 10 is provided in a machine compartment 47 at the rear of the top surface, and an evaporator 16 that serves as a cooler is provided in a cooling compartment 48 at the rear.

[0026] The refrigeration system 10 uses isobutane, a flammable refrigerant with a small global warming potential from the viewpoint of protecting the global environment. This hydrocarbon isobutane has a specific gravity approximately twice that of air at room temperature and atmospheric pressure (2.04 at 300K). This allows a smaller amount of refrigerant to be charged than in the past, resulting in lower costs, and in the unlikely event of a flammable refrigerant leaking, the amount of leakage is reduced, improving safety.

[0027] Next, the configuration of the refrigeration system 10 will be described with reference to FIG.

[0028] The refrigeration system 10 is configured by connecting a compressor 11, a condenser 12, a dryer 13, a capillary tube 15 serving as a throttling means, an evaporator 16, an accumulator 17, a suction pipe 18, and an internal heat exchanger 19. The refrigeration system 10 is also provided with a refrigerant control sensor 23 consisting of a minute resistor 20, an upstream temperature sensor 21, and a downstream temperature sensor 22.

[0029] The microresistor 20 constituting the refrigerant control sensor 23 is made of a thin tube with a length of 250 mm, and has a resistance equivalent to about 5% of the total resistance of the microresistors 20 and the capillary tube 15 arranged in series. The ratio of the microresistor 20 to the total resistance is preferably 1 to 20%. If it is less than 1%, it becomes difficult to measure changes in the state of the refrigerant flowing inside. If it exceeds 20%, heat exchange in the internal heat exchange section 19 becomes insufficient, and the efficiency of the refrigeration system decreases. The ratio of the microresistor 20 to the total resistance is shown as the ratio of the lengths when each resistor is replaced with a capillary tube 15 of the same inner diameter.

[0030] Here, the upstream temperature sensor 21 and downstream temperature sensor 22 that constitute the above-mentioned refrigerant control sensor 23 measure the temperatures upstream and downstream of the micro-resistance 20, which change according to changes in the state of the refrigerant flowing inside the micro-resistance 20, and vary the amount of refrigerant circulating so that the temperature difference approaches a set temperature difference, thereby controlling the refrigeration system 10 to a specified state.

[0031] In the refrigeration system 10, the dryer 13 dries the refrigerant circulating within the refrigeration system 10, and is disposed downstream of the condenser 12 so as to efficiently contact the refrigerant with the liquid refrigerant.

[0032] The accumulator 17 stores excess refrigerant in a stable state, and is disposed downstream of the evaporator 16 to maintain the temperature at approximately the same level as that of the evaporator 16. When the temperature of an object (not shown) to be cooled using the refrigeration system 10 rises, the amount of excess refrigerant stored in the accumulator 17 decreases and the amount of refrigerant circulating in the refrigeration system 10 increases, thereby increasing the refrigeration capacity.

[0033] Generally, in a refrigeration system in which heat dissipation capacity changes significantly depending on environmental conditions, such as a household refrigerator that dissipates heat by natural convection from the outer shell of a housing such as refrigerator body 30, it is not possible to store excess refrigerant on the high-pressure side of the refrigeration system using a receiver, so as in the present embodiment 1, the excess refrigerant is stored on the low-pressure side of the refrigeration system using accumulator 17. Also, the amount of excess refrigerant stored in accumulator 17 is about 10 to 30% of the total refrigerant amount in the refrigeration system, and a function of adjusting the refrigeration capacity with a relatively small amount is obtained, which is effective in suppressing the total amount of refrigerant.

[0034] In addition, by using the capillary tube 15 to form a throttle in the refrigeration system 10, an internal heat exchange section 19 for exchanging heat between the capillary tube 15 and the suction pipe 18 can be realized, and the enthalpy of the low-temperature refrigerant circulating through the suction pipe 18 can be recovered, thereby improving the efficiency of the refrigeration system 10.

[0035] The operation and behavior of the refrigerator configured as above will be described below with reference to Figs. 3 to 5.

[0036] When this refrigerator performs a cooling operation, the refrigerant compressed by compressor 11 is condensed by dissipating heat in condenser 12, and then dried by dryer 13. Then, after passing through refrigerant control sensor 23, the refrigerant is decompressed by capillary tube 15, and then supplied to evaporator 16 to evaporate, and is returned to compressor 11 through suction pipe 18. At this time, cooling is performed by utilizing the cold energy generated in evaporator 16.

[0037] Here, when the temperature of the object (not shown) drops and approaches a stable state while the compressor 11 is in operation, the outlet refrigerant of the condenser 12 is in a two-phase state (preferably, a dryness of 3 to 10% by weight). This is because the total resistance of the minute resistors 20 and the capillary tubes 15 arranged in series and the total amount of refrigerant in the refrigeration system 10 are designed so that the outlet refrigerant of the condenser 12 does not become supercooled even if the temperature of the object (not shown) to be cooled rises, the amount of excess refrigerant stored in the accumulator 17 decreases, and the amount of refrigerant circulating in the refrigeration system 10 increases.

[0038] Generally, in refrigeration systems whose heat dissipation capacity changes significantly depending on environmental conditions, such as household refrigerators that dissipate heat through natural convection from the outer shell of the casing, if the system is designed so that the refrigerant at the condenser outlet is supercooled, there is a concern that when the heat dissipation capacity increases due to environmental conditions, almost all of the refrigerant in the refrigeration system will remain in the condenser, causing an abnormal decrease in the amount of refrigerant circulating.

[0039] In addition, when the heat dissipation capacity decreases due to environmental conditions, the excess refrigerant that could not be condensed in the condenser cannot be stored in the accumulator 17 and flows back from the suction pipe 18 to the compressor 11, which may reduce the durability of the compressor 11.

[0040] Therefore, as described above, in the refrigeration system 10 of the present invention, the total resistance of the minute resistor 20 and the capillary tube 15 arranged in series and the total amount of refrigerant in the refrigeration system 10 are designed so that the refrigerant at the outlet of the condenser 12 is not supercooled.

[0041] When the refrigerant from the condenser 12 in a two-phase state passes through the micro resistance 20, the temperatures upstream and downstream of the micro resistance 20 are detected by the upstream temperature sensor 21 and the downstream temperature sensor 22. Then, the amount of refrigerant circulated is controlled so that the detected temperature difference before and after the micro resistance 20 becomes a predetermined value. As a result, the dryness of the refrigerant at the outlet of the condenser 12 decreases, the refrigeration effect increases, and the efficiency of the refrigeration system 10 can be improved.

[0042] Next, a method for controlling the amount of refrigerant circulated will be described with reference to FIGS.

[0043] The horizontal axis of FIG. 4 represents the rotation speed of the cooling fan 45 that circulates the cold air generated by the evaporator 16 inside the refrigerator, and the vertical axis represents the temperature difference S before and after the minute resistor 20 measured by the refrigerant control sensor 23.

[0044] As described above, when the temperature of the object (not shown) to be cooled by the refrigeration system 10 decreases and approaches a stable state while the compressor 11 is operating, the outlet refrigerant of the condenser 12 enters a two-phase state. At this time, the output of the refrigerant control sensor 23 indicates S0. Then, the rotation speed of the cooling fan 45 is increased so that the output of the refrigerant control sensor 23 falls below S2. As a result, the dryness of the refrigerant at the outlet of the condenser 12 decreases, the refrigeration effect increases, and the efficiency of the refrigeration system 10 improves.

[0045] On the other hand, if the dryness fraction of the refrigerant at the outlet of the condenser 12 continues to decrease and the output of the refrigerant control sensor 23 falls below S1, the rotation speed of the cooling fan 45 is reduced. As a result, the output of the refrigerant control sensor 23 can be stabilized to a state indicating S2 from S1.

[0046] The reason why the lower limit value S1 is set for the output of the refrigerant control sensor 23 is that if the rotation speed of the cooling fan 45 is increased too much, the outlet refrigerant of the condenser 12 becomes supercooled, and almost all the refrigerant in the refrigeration system 10 accumulates in the condenser 12, which may cause an abnormal decrease in the amount of refrigerant circulating. In such a case, the cooling capacity may be insufficient, and the refrigerator may cool slowly, so this must be avoided.

[0047] 5 is the temperature difference S across the microresistor 20 measured by the refrigerant control sensor 23, which is the same as the vertical axis in FIG. 4, and the vertical axis in FIG.

[0048] As described above, when the rotation speed of cooling fan 45 is increased from a state in which the output of refrigerant control sensor 23 indicates S0, heat exchange between the air and refrigerant is promoted in evaporator 16, the evaporation temperature of the refrigerant rises, and the amount of refrigerant circulating increases. Accordingly, the quality of the refrigerant at the outlet of condenser 12 decreases, and the output of refrigerant control sensor 23 drops from S0 to S2. Similarly, when the airflow rate of cooling fan 45 is adjusted to stabilize the output of refrigerant control sensor 23 from S1 to S2, the quality of the refrigerant at the outlet of condenser 12 stabilizes near zero (preferably a quality of 0 to 1% by weight).

[0049] As described above, the minute resistance 20 and the total resistance of the capillary tube 15 are designed so that the refrigerant at the outlet of the condenser 12 does not become supercooled even when the refrigerant circulation amount increases, so when the refrigerant circulation amount decreases, the total resistance of the minute resistance 20 and the capillary tube 15 becomes insufficient. To compensate for the insufficient resistance, the dryness of the refrigerant at the outlet of the condenser 12 increases, and the flow velocity of the refrigerant increases accordingly.

[0050] This increases the resistance of the refrigerant passing through the minute resistor 20 and the capillary tube 15, making up for the insufficient resistance. When the refrigerant circulation volume is large, the dryness fraction of the refrigerant at the outlet of the condenser 12 is close to zero, and as the refrigerant circulation volume decreases, the dryness fraction of the refrigerant at the outlet of the condenser 12 increases.

[0051] In this manner, by controlling the airflow rate of cooling fan 45 according to the output of refrigerant control sensor 23, i.e., the detected temperature difference, so that this approaches the set temperature difference, the dryness of the refrigerant at the outlet of condenser 12 can be stabilized near zero (preferably a dryness of 0 to 1% by weight), thereby increasing the refrigeration effect and improving the efficiency of refrigeration system 10.

[0052] In other words, the above-mentioned refrigerator body 30 controls the cooling fan 45 so that the dryness of the condenser outlet approaches zero using the refrigerant control sensor 23 consisting of the minute resistor 20 and a temperature sensor that measures the temperature difference before and after the minute resistor 20, thereby maximizing the refrigeration capacity using the cooling fan 45 in a refrigeration system that does not have a receiver at the condenser outlet, and enabling highly efficient cooling operation.

[0053] As described above, the first embodiment has been described as an example of the technology disclosed in the present invention. However, the technology in the present disclosure is not limited to this, and can be applied to embodiments in which modifications, substitutions, additions, omissions, etc. are made.

[0054] Therefore, other embodiments will be exemplified below.

[0055] In the first embodiment, the refrigeration capacity is maximized by controlling the cooling fan 45 in accordance with the output of the refrigerant control sensor 23, but this may also be achieved by controlling the rotation speed of the condenser fan 46 provided to promote condensation of the refrigerant in the condenser 12.

[0056] Increasing the rotation speed of the condenser fan 46 promotes heat exchange between the air and the refrigerant in the condenser 12, lowers the condensation temperature of the refrigerant, and improves the volumetric efficiency of the compressor, thereby increasing the amount of refrigerant circulating. Thus, the same effect as when the rotation speed of the cooling fan 45 is increased can be obtained.

[0057] Alternatively, the rotation speed of compressor 11 may be controlled according to the output of refrigerant control sensor 23. When the rotation speed of compressor 11 is increased, the amount of refrigerant circulating increases, and therefore, the same effect as when the airflow rates of cooling fan 45 and condenser fan 46 are increased can be obtained. [Industrial Applicability]

[0058] As described above, the refrigeration system device of the present invention is capable of increasing the cooling efficiency of the refrigerant and improving energy saving, and therefore can be widely applied as a refrigeration cycle device not only in refrigeration-application products such as household or commercial refrigerators, but also in air conditioners and kitchen appliances equipped with a refrigeration cycle. [Explanation of symbols]

[0059] 11 Compressor 12 Condenser 15 Capillary tube (squeezing means) 16 Evaporator 20 Micro resistance 21 Upstream temperature sensor 22 Downstream Temperature Sensor 23 Refrigerant control sensor 30 Refrigerator body 45 Cooling Fan 46 Condenser fan

Claims

1. A refrigeration cycle device having at least a compressor, a condenser, a throttling means, and an evaporator, the refrigeration cycle device comprising a plurality of temperature sensors for detecting the temperature of a refrigerant between the condenser and the throttling means, and a refrigerant circulation amount control means for controlling the amount of refrigerant circulated in accordance with a temperature difference detected by the temperature sensors, the refrigerant circulation amount control means controlling the rotation speed of a cooling fan that circulates cold air generated by the evaporator into a storage compartment, the refrigeration cycle device increasing the rotation speed of the cooling fan so that the temperature difference detected by the temperature sensors falls below an upper threshold, and decreasing the rotation speed of the cooling fan when the temperature difference detected by the temperature sensors falls below a lower threshold.

2. A refrigeration cycle apparatus having at least a compressor, a condenser, a throttling means, and an evaporator, the refrigeration cycle apparatus comprising a plurality of temperature sensors for detecting a temperature of a refrigerant between the condenser and the throttling means, and a refrigerant circulation amount control means for controlling a refrigerant circulation amount in accordance with a temperature difference detected by the temperature sensors, the refrigerant circulation amount control means controlling a rotation speed of a condenser blower of the condenser, the refrigeration cycle apparatus increasing the rotation speed of the condenser blower so that the temperature difference detected by the temperature sensors falls below an upper threshold, and decreasing the rotation speed of the condenser blower when the temperature difference detected by the temperature sensors falls below a lower threshold.

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