Refrigeration cycle device and refrigerator

Abstract

To provide a refrigeration cycle device capable of enhancing power-saving effect by switching between normal operation and power-saving operation on the basis of a refrigerant state.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. Energy can be effectively and efficiently saved by switching between normal operation and power-saving operation on the basis of a difference in temperatures detected by the upstream temperature sensor 21 and the downstream temperature sensor 22.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a refrigeration cycle device, such as a refrigerator, that can efficiently perform power-saving operation. [Background technology]

[0002] Conventionally, refrigerators, which are one type of refrigeration cycle devices, are often provided with a power-saving mode during cooling operation that is more effective at saving power than normal operation, and some refrigerators detect the illuminance around the refrigerator and perform power-saving operation according to the detected illuminance (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2005-55062 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the conventional configuration, since the power-saving operation is started depending on the illuminance around the refrigerator, if the lights are on during the day or night, the power-saving operation is not performed. For example, even if the inside of the refrigerator is sufficiently cold, the power-saving operation is not performed depending on the illuminance around the refrigerator, and therefore, there is a problem that the power-saving operation cannot be performed effectively and efficiently.

[0005] The present invention is intended to solve the above-mentioned conventional problems, and aims to provide a refrigeration cycle device that can perform effective and efficient power-saving operation by performing power-saving operation according to the state of refrigerant in the refrigeration cycle. [Means for solving the problem]

[0006] 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 equipped with a plurality of temperature sensors for detecting the temperature of the refrigerant between the condenser and the throttling means, and a control means for controlling the operation of the refrigeration cycle device, and is characterized in that the control means switches the refrigeration cycle device from normal operation to a power-saving operation in which power consumption during operation is reduced compared to the normal operation based on the temperature difference detected by the temperature sensors. Effect of the Invention

[0007] The refrigeration cycle device of the present invention can carry out an effective and efficient power saving operation. [Brief description of the drawings]

[0008] [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] Control block diagram of a refrigerator in the first embodiment [Diagram 5] FIG. 13 is a diagram showing a correlation between a temperature difference before and after a minute resistance of a refrigerator in the first embodiment and a dryness fraction at a condenser outlet. [Figure 6] Control flow chart of the refrigerator in the first embodiment DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] A first invention is a refrigeration cycle apparatus having at least a compressor, a condenser, a throttling means, and an evaporator, comprising a plurality of temperature sensors for detecting the temperature of a refrigerant between the condenser and the throttling means, and a control means for controlling the operation of the refrigeration cycle apparatus, wherein the control means switches the refrigeration cycle apparatus from normal operation to a power-saving operation in which power consumption during operation is reduced compared to the normal operation based on a temperature difference detected by the temperature sensors.

[0010] This makes it possible to estimate the dryness of the refrigerant at the condenser outlet from the difference in the detected temperatures of the refrigerant, determine whether the refrigerant is in a stable state from the estimated dryness of the refrigerant, and when it is determined to be in a stable state, quickly switch from normal operation to power-saving operation, thereby enabling effective and efficient power-saving operation, and thereby reducing the power consumption of the refrigeration cycle device.

[0011] A second invention is a refrigeration cycle apparatus described in the first invention, characterized in that the control means switches the refrigeration cycle apparatus from the power saving operation to the normal operation based on the detected temperature difference of the temperature sensor.

[0012] This allows the refrigerator to quickly switch from power-saving operation to normal operation when the refrigerant goes from a stable state to an unstable state during power-saving operation, and prevents delays in cooling even when the interior of the refrigerator needs to be cooled quickly, such as when items are put into the refrigerator.

[0013] In this manner, by switching between normal operation and power-saving operation based on the stable state of the refrigerant in the refrigerator, the refrigerator can be operated effectively and efficiently.

[0014] 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.

[0015] (Embodiment 1) Hereinafter, a refrigerator will be described as an embodiment of the refrigeration cycle device with reference to Figs. 1 to 6.

[0016] 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, FIG. 3 is a cycle configuration diagram of the refrigerator according to embodiment 1, FIG. 4 is a control block diagram of the refrigerator in embodiment 1, FIG. 5 is a diagram showing the correlation between the temperature difference before and after the minute resistance of the refrigerator in embodiment 1 and the dryness fraction at the condenser outlet, and FIG. 6 is a control flowchart of the refrigerator in embodiment 1.

[0017] As shown in Figures 1 to 3, this refrigerator has an insulating refrigerator body 30 consisting of a metal (e.g., iron plate) outer box that opens to the front, a hard resin (e.g., ABS) inner box, and an insulating material such as hard urethane foam that is foamed and filled between the outer box and the inner box.

[0018] Within the refrigerator body 30, there are 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 side by side upper freezer compartment 32 and ice-making compartment 33, and a vegetable compartment 35 below the lower freezer compartment 34.

[0019] The front of the refrigerator compartment 31 is closed by, for example, a double-door that can be opened and closed freely, and the front portions of the upper freezer compartment 32, the ice-making compartment 33, the lower freezer compartment 34, and the vegetable compartment 35 are closed by pull-out doors that can be opened and closed freely.

[0020] The refrigerator compartment 31 is normally set at a temperature of 1 to 5° C., the lower limit of which is sufficient to prevent freezing for refrigerated storage. The vegetable compartment 35 is set at a temperature of 2 to 7° C., which is the same as or slightly higher than that of the refrigerator compartment 31, and the low temperature makes it possible to maintain the freshness of leafy vegetables for a long period of time.

[0021] The upper freezer compartment 32 and the lower freezer compartment 34 are normally set at -22 to -18°C for frozen storage, but to improve the frozen storage conditions, they may be set at a lower temperature, for example, -30 to -25°C. The upper freezer compartment 32 may also be used as a switchable compartment, allowing the temperature range to be selected from the refrigeration temperature range to the freezing temperature range by using a damper mechanism or the like.

[0022] The refrigerator body 30 is provided with a refrigeration system 10 that cools the refrigerator compartment 31, upper freezer compartment 32, ice-making compartment 33, lower freezer compartment 34, and 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.

[0023] 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.

[0024] Next, the configuration of the refrigeration system 10 will be described with reference to FIG.

[0025] 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.

[0026] 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 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.

[0027] If it exceeds 20%, the heat exchange in the internal heat exchange section 19 becomes insufficient, and the efficiency of the refrigeration system decreases. Note that the ratio of the minute resistance 20 to the total resistance is shown as the ratio of the length when each resistance is replaced with a capillary tube 15 of the same inner diameter.

[0028] Here, the upstream temperature sensor 21 and downstream temperature sensor 22 that constitute the refrigerant control sensor 23 measure the temperatures upstream and downstream of the microresistor 20, which change in response to changes in the state of the refrigerant flowing inside the microresistor 20.

[0029] 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.

[0030] 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.

[0031] Generally, in a refrigeration system in which the 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.

[0032] In addition, the amount of excess refrigerant stored in accumulator 17 is set to about 10 to 30% of the total amount of refrigerant in the refrigeration system, and a function of adjusting the refrigeration capacity can be obtained with a relatively small amount, which is effective in suppressing the total amount of refrigerant.

[0033] 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.

[0034] The operation and behavior of the refrigerator configured as above will be described below with reference to Figs. 3 to 6.

[0035] In Fig. 3, when the 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 be evaporated, 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.

[0036] Here, when the temperature of the object (not shown) decreases and approaches a stable state while the compressor 11 is operating, the outlet refrigerant of the condenser 12 becomes a two-phase state (preferably with a dryness of 3 to 10% by weight).

[0037] This is because the total resistance of the micro 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 refrigerant at the outlet of the condenser 12 does not become supercooled even if the temperature of the object to be cooled (not shown) 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] In general, in a refrigeration system whose heat dissipation capacity changes greatly depending on environmental conditions, such as a household refrigerator that dissipates heat from the outer shell of the casing by natural convection, if the refrigerant at the outlet of the condenser is designed to be 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. Also, 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 will return from the suction pipe 18 to the compressor 11, causing a concern that the durability of the compressor 11 will decrease.

[0039] 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.

[0040] 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, based on the detected temperature difference before and after the micro-resistance 20, the control means 80 switches between normal operation and power-saving operation.

[0041] Next, the control configuration of each component will be explained using the control block diagram in Figure 4. In Figure 4, a signal from refrigerant control sensor 23 is input to control means 80. Refrigerant control sensor 23 is composed of upstream temperature sensor 21 and downstream temperature sensor 22. In addition, signals for controlling each electrical load component are output from control means 80 to compressor 11, cooling fan 45, and condenser fan 46, respectively.

[0042] Next, the movement of the refrigerant passing through the minute resistance 20 will be described with reference to FIG. 5, which shows the correlation between the temperature difference before and after the minute resistance and the dryness fraction at the condenser outlet.

[0043] As described above, when the temperature of the object (not shown) to be cooled using the refrigeration system 10 decreases while the compressor 11 is operating and the refrigeration system approaches a stable state, the outlet refrigerant of the condenser 12 becomes a two-phase state and the dryness fraction increases.

[0044] As the dryness fraction increases, the proportion of gas phase refrigerant at the outlet of the condenser 12 increases, so the refrigerant flow rate increases and the pressure loss when passing through the piping increases, and therefore the temperature difference S before and after the minute resistor 20 measured by the refrigerant control sensor 23 increases.

[0045] From these characteristics, the following can be considered: That is, the larger the temperature difference S before and after the minute resistance 20, the greater the dryness of the refrigerant, and the more stable the refrigeration system is.

[0046] Therefore, by observing the magnitude of the temperature difference S before and after the minute resistance 20, the stable state of the refrigeration system can be determined.

[0047] Next, a control method by the control means 80 using the temperature difference S before and after the minute resistor 20 will be described with reference to the control flow chart of FIG.

[0048] First, in step 1 during normal operation, while the compressor 11 is operating, the temperature difference before and after the minute resistance is detected by the refrigerant control sensor 23 and input to the control means 80. The control means 80 determines whether the temperature difference before and after the minute resistance is equal to or greater than S0, and if it is equal to or greater than S0, proceeds to step 2, and if not, normal operation is continued.

[0049] Next, in step 2, the normal operation is switched to the power-saving operation, and the power-saving operation is started.

[0050] Next, in step 3, while the compressor 11 is operating, the temperature difference before and after the minute resistance is detected by the refrigerant control sensor 23 and input to the control means 80. The control means 80 judges whether the temperature difference before and after the minute resistance is equal to or less than S1. If it is equal to or less than S1, the process proceeds to step 4, and if it is not, the power saving operation is continued. Next, in step 4, the power saving operation is switched to normal operation, and normal operation is started.

[0051] Here, the power saving operation will be described. As described above, the refrigerator body 30 according to the present embodiment 1 configures a refrigeration cycle with the compressor 11, the condenser 12, the evaporator 16, etc., and also has components that are targets of power saving, such as the cooling fan 45 that circulates the cold air generated by the evaporator 16, the condenser fan 46 that promotes the condensation of the refrigerant in the condenser 12, a heater that compensates for the temperature inside the refrigerator body, and a heater that prevents condensation and freezing.

[0052] By controlling the above-mentioned items that are the targets of power saving, it is possible to carry out a power saving operation in which power consumption is reduced more than in the cooling operation in normal operation. In this power saving operation, the following control is carried out.

[0053] For example, the power consumption by the compressor 11 may be reduced by lowering the rotation speed of the compressor 11 below the rotation speed in normal operation. Also, for example, the power consumption by the cooling fan 45 may be reduced by lowering the rotation speed of the cooling fan 45 that circulates the cold air generated by the evaporator 16 inside the refrigerator below the rotation speed in normal operation.

[0054] In addition, for example, the power consumption by the condenser fan 46 may be reduced by lowering the rotation speed of the condenser fan 46, which is provided to promote condensation of the refrigerant in the condenser 12, below the rotation speed during normal operation.

[0055] In addition, for example, the set temperature inside the cabinet may be set higher than the set temperature during normal operation to reduce the amount of cooling required to maintain the temperature inside the cabinet, and the power consumption of compressor 11 may be reduced by shortening the operating time of compressor 11.

[0056] In the power saving operation, the temperature inside the refrigerator may be lowered for all storage compartments, or for any storage compartment, such as only the refrigerator compartment 31. In addition, the power consumption may be reduced by reducing the output of the heater to prevent condensation and freezing of the refrigerator body.

[0057] As described above, the embodiments have been described as examples of the technology disclosed in the present invention. However, the technology in the present disclosure is not limited to the above, and can be applied to embodiments in which modifications, substitutions, additions, omissions, etc. are made.

[0058] (Other embodiments) As described above, the first embodiment has been described as an example of the technology disclosed in the present application. 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. In addition, it is also possible to combine the components described in the first embodiment to create new embodiments.

[0059] Therefore, other embodiments will be exemplified below.

[0060] In the first embodiment, switching between normal operation and power-saving operation is performed based on the temperature difference before and after the microresistance 20 detected by the refrigerant control sensor 23, but switching between normal operation and power-saving operation may also be performed based on the illuminance around the refrigerator as well as the temperature difference before and after the microresistance.

[0061] Specifically, even if the temperature difference before and after the minute resistance is less than S0, if it can be determined that the illuminance around the refrigerator is equal to or lower than a predetermined illuminance and it is late at night, for example, the power saving operation may be performed.

[0062] Furthermore, switching between normal operation and power-saving operation may be performed based on the temperature difference before and after the minute resistance as well as the number of times the door is opened and closed of refrigerator main body 30. Specifically, even if the temperature difference before and after the minute resistance is less than S0, for example, if the number of times the door is opened and closed per unit time of refrigerator main body 30 is equal to or less than a predetermined number, and it can be determined that the time period is one in which the user uses the refrigerator less frequently, power-saving operation may be performed.

[0063] In addition, switching between normal operation and power saving operation may be performed based on the internal temperature of the refrigerator body 30 as well as the temperature difference before and after the minute resistance.

[0064] Specifically, even if the temperature difference before and after the minute resistance is less than S0, if, for example, the temperature inside the refrigerator body 30 is equal to or lower than a predetermined temperature and it can be determined that the inside of the refrigerator is sufficiently cooled, power saving operation may be performed.

[0065] In this way, by combining the method of switching from normal operation to power-saving operation based on the temperature difference before and after microresistance 20 detected by refrigerant control sensor 23 of the present invention with the conventional method of switching based on the illuminance around the refrigerator, the number of times the door is opened and closed, the temperature inside the refrigerator, etc., it is possible to implement a more effective and efficient power-saving operation.

[0066] Furthermore, for switching from normal operation to power saving operation, the evaporation temperature of the refrigerant passing through the evaporator may be used instead of the temperature difference across the microresistance 20 detected by the refrigerant control sensor 23.

[0067] The evaporation temperature of the refrigerant also has different temperature trends in a stable state and an unstable state, so it has the same effect as the method based on the temperature difference before and after the minute resistor 20. In addition, by using the evaporation temperature, it becomes unnecessary to install the refrigerant control sensor 23, so the introduction cost can be reduced.

[0068] Furthermore, with regard to switching from normal operation to power-saving operation, a coefficient of performance derived from data during operation of the refrigerator may be used instead of the temperature difference before and after micro resistance 20 detected by refrigerant control sensor 23. The coefficient of performance of the refrigerator also has different numerical trends between a stable state and an unstable state, so that the same effect as the method based on the temperature difference before and after micro resistance 20 can be obtained.

[0069] In this way, when switching from normal operation to power saving operation, the same effect can be obtained if a method can be used to determine the state of the refrigerant other than the temperature difference across the microresistance 20 detected by the refrigerant control sensor 23 of the present invention. [Industrial Applicability]

[0070] As described above, the refrigeration system device of the present invention enables effective and efficient power-saving operation, and therefore can be widely applied as a refrigeration cycle device for air conditioners, kitchen appliances, and the like equipped with a refrigeration cycle, as well as refrigeration-application products such as household or commercial refrigerators. [Explanation of symbols]

[0071] 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 80 Control Means

Claims

1. A refrigeration cycle device having at least a compressor, a condenser, a throttling means, and an evaporator, wherein a microresistance smaller than the throttling means is provided between the condenser and the throttling means, and an upstream temperature sensor that detects the temperature of the refrigerant upstream of the microresistance and a downstream temperature sensor that detects the temperature of the refrigerant downstream of the microresistance are provided, and a control means that controls the operation of the refrigeration cycle device switches the refrigeration cycle device from normal operation to power-saving operation in which power consumption during operation is reduced more than that of the normal operation based on the detected temperature difference between the upstream temperature sensor and the downstream temperature sensor if the temperature difference between the microresistance is equal to or greater than an upper threshold, and switches from power-saving operation to normal operation if the temperature difference between the microresistance is equal to or less than a lower threshold.

2. A refrigerator comprising the refrigeration cycle device according to claim 1.

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