JP7607192B2 - Refrigeration Cycle Equipment - Google Patents

Description

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 in a refrigerant pipe.

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

Figure 6 shows a method for controlling the compressor and cooling fan of a conventional refrigeration cycle described in Patent Document 1.

As shown in FIG. 6, the internal temperature detection circuit 151 detects the internal temperature in the storage compartment using an internal temperature sensor 150 installed in the storage compartment, and outputs the temperature data to the 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 the set temperature, and outputs a corresponding control command signal to the compressor drive circuit 153 and the cooling fan drive circuit 154 to control the rotation speed of the compressor 141 and the rotation speed of the cooling fan 142.

Japanese Patent Application Publication No. 1-33485

However, in the conventional configuration, the rotation speed of the compressor and 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. This causes problems such as a decrease in the cooling efficiency of the refrigerant 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.

The present invention aims to solve the above-mentioned problems of the conventional technology and provide a refrigeration cycle device that improves the cooling efficiency of the refrigerant.

In order to solve the above-mentioned problems, 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 amount control means that controls the refrigerant circulation amount according to the temperature difference detected by the temperature sensors.

The refrigeration cycle device of the present invention can increase the cooling efficiency of the refrigerant and improve energy conservation.

FIG. 1 is a front view of a refrigerator as a refrigeration cycle device according to a first embodiment. FIG. 1 is a vertical cross-sectional view of a refrigerator according to a first embodiment. Cycle configuration diagram of a refrigerator in embodiment 1 FIG. 1 is a diagram showing a method for controlling a cooling fan of a refrigeration cycle in the first embodiment. FIG. 13 is a diagram showing the correlation between the output of the refrigerant control sensor and the amount of refrigerant circulating in the refrigeration cycle in the first embodiment. A diagram showing a conventional method for controlling the cooling fan of a refrigeration cycle

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 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 amount control means that controls the amount of refrigerant circulation in accordance with the temperature difference detected by the temperature sensors.

This makes it possible to estimate the dryness 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 circulating so that the detected temperature difference approaches a set temperature difference, the dryness of the refrigerant at the condenser outlet can be brought closer to zero. This increases the cooling efficiency of the refrigeration system, maximizing refrigeration capacity and improving energy savings.

The second invention is the refrigeration cycle device according to 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.

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. This increases the cooling efficiency of the refrigeration system, maximizing the refrigeration capacity and improving energy savings.

The third invention is the refrigeration cycle device according to 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.

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. This increases the cooling efficiency of the refrigeration system, maximizing the refrigeration capacity and improving energy savings.

The fourth invention is the refrigeration cycle device according to the first invention, characterized in that the refrigerant circulation amount control means controls the rotation speed of the compressor.

This allows the compressor's rotation speed to be controlled so that the dryness of the refrigerant at the condenser outlet approaches zero. This increases the cooling efficiency of the refrigeration system, maximizing the refrigeration capacity and improving energy savings.

The following describes an embodiment of the present invention with reference to the drawings. Note that the present invention is not limited to this embodiment.

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

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

As shown in Figs. 1 to 3, this refrigerator has an insulating refrigerator body 30 consisting of a metal (e.g., steel 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. Inside the refrigerator body 30, there is a refrigerator chamber 31, an upper freezer chamber 32 below the refrigerator chamber 31 and an ice-making chamber 33 arranged side by side thereto, a lower freezer chamber 34 below the upper freezer chamber 32 and ice-making chamber 33 arranged side by side thereto, and a vegetable chamber 35 below the lower freezer chamber 34. The front of the refrigerator chamber 31 is closed by, for example, a double-door type door that can be opened and closed freely, and the front parts of the upper freezer chamber 32, the ice-making chamber 33, the lower freezer chamber 34, and the vegetable chamber 35 are closed by drawer-type doors that can be opened and closed freely.

The refrigerator compartment 31 is set at a temperature of 1 to 5°C, the lowest limit at which food will not freeze, for refrigerated storage. The vegetable compartment 35 is set at a temperature of 2 to 7°C, 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 usually 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 conditions.

The upper freezer compartment 32 can also be used as a switchable compartment, allowing the temperature range to be selected from refrigeration to freezing by using a damper mechanism or the like.

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.

The refrigeration system 10 uses isobutane, a flammable refrigerant with a low global warming potential from the perspective of protecting the global environment. This hydrocarbon isobutane has a specific gravity that is approximately twice that of air at room temperature and atmospheric pressure (2.04 at 300 K). This allows for a reduction in the amount of refrigerant required compared to conventional systems, resulting in lower costs, and in the unlikely event of a flammable refrigerant leak, the amount of leakage is reduced, improving safety.

Next, the configuration of the refrigeration system 10 will be explained using Figure 3.

The refrigeration system 10 is composed of a compressor 11, a condenser 12, a dryer 13, a capillary tube 15 (which serves 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 microresistor 20, an upstream temperature sensor 21, and a downstream temperature sensor 22.

The microresistor 20 constituting the refrigerant control sensor 23 is a thin tube with a length of 250 mm, and has a resistance equivalent to approximately 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 the change in the state of the refrigerant flowing inside. 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 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.

The upstream temperature sensor 21 and downstream temperature sensor 22 that constitute the refrigerant control sensor 23 measure the temperature upstream and downstream of the microresistor 20, which changes according to changes in the state of the refrigerant flowing inside the microresistor 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.

In the above refrigeration system 10, the dryer 13 dries the refrigerant circulating within the refrigeration system 10, and is placed downstream of the condenser 12 to efficiently contact the refrigerant with the liquid refrigerant.

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 the evaporator 16. When the temperature of the 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 within the refrigeration system 10 increases, thereby increasing the refrigeration capacity.

In general, 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 the casing of the 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 first embodiment, the excess refrigerant is stored on the low-pressure side of the refrigeration system using an accumulator 17. In addition, the amount of excess refrigerant stored in the accumulator 17 is about 10 to 30% of the total amount of refrigerant in the refrigeration system, and since a function of adjusting the refrigeration capacity can be obtained with a relatively small amount, it is effective in suppressing the total amount of refrigerant.

In addition, by using the capillary tube 15 to form a restriction in the refrigeration system 10, an internal heat exchange section 19 that exchanges heat between the capillary tube 15 and the suction pipe 18 can be realized, and the enthalpy of the low-temperature refrigerant circulating inside the suction pipe 18 can be recovered to improve the efficiency of the refrigeration system 10.

The operation and function of the refrigerator configured as above will be explained below with reference to Figures 3 to 5.

When this refrigerator performs cooling operation, the refrigerant compressed by the compressor 11 is condensed by dissipating heat in the condenser 12, and then dried in the dryer 13. After passing through the refrigerant control sensor 23, the refrigerant is depressurized in the capillary tube 15, and then supplied to the evaporator 16 where it evaporates and flows back to the compressor 11 via the suction pipe 18. At this time, cooling is performed using the cold energy generated by the evaporator 16.

When the compressor 11 is in operation and the temperature of the object (not shown) drops and approaches a stable state, the outlet refrigerant of the condenser 12 is in a two-phase state (preferably with a dryness of 3 to 10% by weight). This is because the total resistance of the serially arranged minute resistors 20 and capillary tubes 15, 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 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.

In general, in refrigeration systems whose heat dissipation capacity changes significantly depending on environmental conditions, such as household refrigerators that dissipate heat from the exterior of the housing through natural convection, if the system is designed so that the refrigerant at the outlet of the condenser 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.

In addition, when the heat dissipation capacity is reduced 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 raises concerns about a decrease in the durability of the compressor 11.

Therefore, as described above, in the refrigeration system 10 of the present invention, the total resistance of the serially arranged micro resistors 20 and capillary tube 15, 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.

When the refrigerant from the condenser 12 in a two-phase state passes through the microresistance 20, the upstream temperature sensor 21 and downstream temperature sensor 22 detect the temperatures upstream and downstream of the microresistance 20. The amount of refrigerant circulating is then controlled so that the detected temperature difference before and after the microresistance 20 becomes a predetermined value. As a result, the dryness of the refrigerant at the outlet of the condenser 12 decreases, increasing the refrigeration effect and improving the efficiency of the refrigeration system 10.

Next, the method for controlling the refrigerant circulation amount will be explained based on Figures 4 and 5.

The horizontal axis of Figure 4 is the rotation speed of the cooling fan 45 that circulates the cold air generated by the evaporator 16 inside the cabinet, and the vertical axis is the temperature difference S before and after the microresistance 20 measured by the refrigerant control sensor 23.

As described above, when the temperature of the object (not shown) being cooled using 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. The rotation speed of the cooling fan 45 is then increased so that the output of the refrigerant control sensor 23 falls below S2. As a result, the dryness of the outlet refrigerant of the condenser 12 decreases, the refrigeration effect increases, and the efficiency of the refrigeration system 10 improves.

On the other hand, if the dryness 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 instead of S1.

The reason for setting a lower limit S1 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 will become supercooled, causing almost all of the refrigerant in the refrigeration system 10 to accumulate in the condenser 12, raising concerns that the amount of refrigerant circulating will drop abnormally. In such a case, the cooling capacity will be insufficient, and the refrigerator may cool slowly, so this must be avoided.

The horizontal axis of FIG. 5 is the temperature difference S before and after the microresistor 20 measured by the refrigerant control sensor 23, which is the same as the vertical axis of FIG. 4, and the vertical axis of FIG. 5 is the amount of refrigerant circulating through the microresistor 20, Q.

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

As mentioned above, the total resistance of the micro-resistance 20 and the capillary tube 15 is designed so that the refrigerant at the outlet of the condenser 12 does not become supercooled even if the amount of refrigerant circulating increases. Therefore, if the amount of refrigerant circulating decreases, the total resistance of the micro-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 rate of the refrigerant increases accordingly.

As a result, the resistance of the refrigerant passing through the microresistor 20 and the capillary tube 15 increases, making up for the lack of resistance. When the amount of refrigerant circulating is large, the dryness of the refrigerant at the outlet of the condenser 12 is close to zero, and as the amount of refrigerant circulating decreases, the dryness of the refrigerant at the outlet of the condenser 12 increases.

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

In other words, the refrigerator body 30 described above uses the refrigerant control sensor 23, which is made up of a microresistance 20 and a temperature sensor that measures the temperature difference before and after the microresistance 20, to control the cooling fan 45 so that the dryness of the condenser outlet approaches zero, 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.

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

Therefore, other embodiments are given below as examples.

In the first embodiment, the cooling fan 45 is controlled according to the output of the refrigerant control sensor 23 to maximize the refrigeration capacity, but this may also be achieved by controlling the rotation speed of the condenser fan 46, which is provided to promote condensation of the refrigerant in the condenser 12.

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. This provides the same effect as when the rotation speed of the cooling fan 45 is increased.

Alternatively, the rotation speed of the compressor 11 may be controlled according to the output of the refrigerant control sensor 23. Increasing the rotation speed of the compressor 11 increases the amount of refrigerant circulating, and thus produces the same effect as increasing the airflow of the cooling fan 45 and the condenser fan 46.

As described above, the refrigeration system device of the present invention is capable of increasing the cooling efficiency of the refrigerant and improving energy conservation, and therefore can be widely used as a refrigeration cycle device in, for example, air conditioners and kitchen appliances equipped with a refrigeration cycle, as well as in refrigeration-application products such as household or commercial refrigerators.

11 Compressor 12 Condenser 15 Capillary tube (throttling means)
16 Evaporator 20 Microresistor 21 Upstream temperature sensor 22 Downstream temperature sensor 23 Refrigerant control sensor 30 Refrigerator body 45 Cooling fan 46 Condenser fan

Claims (2)

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