JPH07151432A - Insufficient refrigerant detector for refrigerator - Google Patents

Abstract

PURPOSE:To provide an apparatus for accurately, early detecting insufficiency of refrigerant due to leakage of the refrigerant occurring in a refrigerator. CONSTITUTION:A compressor 3, a condenser 4, a liquid receiver 6, an expansion valve 7 and a cooler 8 are sequentially circularly connected by a tube to form a refrigerant circuit 9. A flowmeter 2 for measuring a flow rate of the refrigerant flowing through the circuit 9 is provided at an outlet side of the receiver 6. A microcomputer judges that the circuit 9 is short of the refrigerant when a flow rate output from the flowmeter 2 becomes a predetermined high value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerant shortage detecting device in a refrigerator in which a compressor, a condenser, a liquid receiver, a decompression device and a cooler are sequentially connected in an annular pipe.

[0002]

2. Description of the Related Art Conventionally, a refrigerator such as a low-temperature showcase or a refrigerator constitutes a refrigerant circuit by connecting a compressor, a condenser, a liquid receiver, a decompression device and a cooler in sequence to form a refrigerant circuit. A certain amount of refrigerant (eg R-22
(Refrigerant) is enclosed. Then, after the refrigerant gas that is compressed by the compressor and becomes high temperature and is discharged is condensed and liquefied by the condenser, it is temporarily stored in the liquid receiver and only the liquid refrigerant is taken out from the lower part of the liquid receiver to reduce the pressure. After decompressing with, the heat is absorbed from the surroundings by flowing into a cooler and evaporating to exert a cooling effect.

[0003]

When the refrigerant (gas) leaks from the refrigerant circuit of the refrigerator, a shortage of the refrigerant occurs and the liquid refrigerant stored in the liquid receiver begins to be exhausted.
Therefore, the gas refrigerant flows out from the liquid receiver to generate flash gas. When such a flash gas is generated, it becomes impossible to supply a sufficient amount of the reduced pressure refrigerant to the cooler, and the cooling capacity of the refrigerator rapidly decreases.

Conventionally, a sight glass is provided in the pipe on the outlet side of the liquid receiver and the generation of the flash gas is visually detected, but unless the administrator looks into the sight glass and monitors it. However, it was extremely complicated, and there was a high risk of being overlooked. Further, when the cooling capacity is reduced due to insufficient refrigerant, the rate of temperature decrease in the cooled space becomes slow.However, even if an attempt is made to automatically detect insufficient refrigerant due to a change in the temperature decrease rate, the rate of decrease in a large load state Since it cannot be distinguished from change (slowness), there is a problem that the detection accuracy becomes extremely low.

The present invention has been made in order to solve the above-mentioned conventional technical problems, and provides an apparatus capable of accurately and early detecting a refrigerant shortage due to refrigerant leakage occurring in a refrigerator. The purpose is to provide.

[0006]

A refrigerant shortage detection device according to the present invention is a refrigerating machine in which a compressor, a condenser, a liquid receiver, a decompression device and a cooler are sequentially connected in an annular pipe to form a refrigerant circuit. Is installed on the outlet side of the receiver,
It consists of a refrigerant flow rate measuring means for measuring the flow rate of the refrigerant flowing in the refrigerant circuit, and a control means for inputting the output of the refrigerant flow rate measuring means, and the control means has a predetermined flow rate output by the refrigerant flow meter side means. When the value becomes high, it is determined that the refrigerant in the refrigerant circuit is insufficient.

Further, in addition to the above, the refrigerant shortage detection device of the invention of claim 2 is provided with a temperature detection means for detecting the temperature of the cooled space or the temperature of the cool air supplied to the cooled space, and the control means is When the flow rate output by the refrigerant flow meter side means has a predetermined high value and the rate of decrease in the temperature is slow, it is determined that the refrigerant in the refrigerant circuit is insufficient.

Furthermore, in addition to the invention of claim 1, the refrigerant shortage detection device of the third aspect of the invention is such that the control means prohibits the determination of the lack of the refrigerant for a certain period after defrosting of the cooler.

[0009]

When a predetermined amount of the refrigerant is filled in the refrigerant circuit, the flow rate GR of the liquid refrigerant flowing out of the receiver temporarily rises when the cooler is pulled down after defrosting (for example, as shown in the upper part of FIG. 4). 1.5 liters / minute), but during a normal thermocycle operation, a substantially constant amount (for example, 1 liter / minute)
Minutes). The temperature T in the figure is, for example, the temperature of cold air discharged to the low temperature showcase. However, when the refrigerant leaks from the refrigerant circuit and the liquid refrigerant in the receiver is depleted, and flash gas is generated in the refrigerant flowing out of the receiver, the refrigerant flow rate from the receiver is shown in the bottom of the figure. As described above, the value rises to a value (for example, 2.0 liters / minute or more) that is abnormally higher than the normal value (1 to 1.5 liters / minute).

According to the refrigerant shortage detection device of the present invention, the refrigerant flow rate measuring means is provided on the outlet side of the liquid receiver of the refrigerant circuit of the refrigerator, and the control means controls the flow rate output by the refrigerant flow meter side means. When it becomes a predetermined high value, it is determined that the refrigerant in the refrigerant circuit is insufficient. Therefore, it is possible to quickly detect the generation of flash gas at the outlet side of the liquid receiver and determine that the refrigerant is insufficient. Therefore, it becomes possible to detect the occurrence of poor cooling at an early stage and issue a prediction warning or the like. In particular, since the determination is made by directly detecting the refrigerant flow rate, not by the temperature change state alone, it is possible to improve the refrigerant shortage detection accuracy.

Even when flash gas is generated on the outlet side of the liquid receiver, the interior (cooled space) of the low-temperature showcase may be cold, especially in winter. In such a case, although the abnormality is predicted, there is no practical problem, so issuing an alarm or the like has no substantial meaning. In addition to the invention of claim 1, the refrigerant shortage detecting device of the invention of claim 2 is provided with temperature detecting means for detecting the temperature of the cooled space or the temperature of the cold air supplied to the cooled space, and the control means is When the flow rate output by the refrigerant flow meter side means has a predetermined high value, and the rate of decrease in temperature is slow, it is determined that there is insufficient refrigerant in the refrigerant circuit, and therefore flash gas is generated in the winter, etc. Regardless of the occurrence, if the space to be cooled (inside the low temperature showcase) is actually cold, it is not judged as abnormal. Therefore, it is possible to prevent a substantially unnecessary alarm from being generated.

Further, even when no refrigerant leakage occurs in the refrigerant circuit, flash gas is likely to be generated at the outlet side of the receiver when pulling down the cooler after defrosting.
In addition to the invention of claim 1, the refrigerant shortage detection device of the invention of
Since the control means prohibits the refrigerant shortage determination for a certain period after the defrosting of the cooler, it is possible to prevent the generation of an unnecessary alarm due to the temporary flash gas generated during the pulldown after the defrosting.

[0013]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a block diagram of an electric circuit of a refrigerant shortage detection device 1 of the present invention, FIG. 2 is a refrigerant circuit diagram of a low temperature showcase S, S and a refrigerator R as an example of a refrigerator, and FIG. 3 is a refrigerant flow rate measuring means. It is a vertical side view of the flow meter 2 of FIG. In FIG. 2, the compressor 3, the condenser 4, the liquid receiver 6, the expansion valves 7, 7, 7 as the pressure reducing device, and the coolers 8, 8, 8 are sequentially connected in an annular shape by a refrigerant pipe to form a refrigerant circuit 9. Are configured.

Of these, the expansion valves 7 and the coolers 8 are connected in series with the liquid solenoid valves 11, 11, 11 and their sets are connected in parallel, and the respective coolers 8, 8, 8 are connected. For example, the low temperature showcases S and S and the refrigerator R installed in a store such as a supermarket are installed in the refrigerator. A sight glass 13 and a flow meter 2 are sequentially opened in the refrigerant pipe on the refrigerant outlet side of the liquid receiver 6.

In the refrigerant circuit 9, a predetermined amount, for example, 13
kg of R-22 refrigerant is enclosed. Then, when the compressor 3 is operated, the gas refrigerant that is compressed by the compressor 3 and has a high temperature and is discharged is condensed and liquefied by the condenser 4 and then temporarily stored in the liquid receiver 6. The liquid refrigerant and the gas refrigerant are separated in the liquid receiver 6, and only the liquid refrigerant flows out from the lower part of the liquid receiver 6. Then, after flowing through the sight glass 13 and the flow meter 2, the flow is divided, the pressure is reduced by the expansion valve 7 ... via the liquid solenoid valve 11 ..., and then flows into the cooler 8.
The decompressed refrigerant evaporates in each cooler 8 and absorbs heat from the surroundings to exert a cooling effect. Thereby, the low temperature showcase S or the refrigerator R is cooled to a predetermined freezing or refrigerating temperature.

The flow meter 2 has a main body 14 as shown in FIG.
A refrigerant inlet 16 and a refrigerant outlet 17 connected to the refrigerant pipe are provided in the front and rear of the above, and a rotor (blade) 18 provided with a magnet is built in the main body 14 located between them. Further, a magnetic sensor 19 is mounted in the main body 14 close to the rotor 18. Flowmeter 2 as described above
When the refrigerant flows through the inside, the refrigerant flows from the refrigerant inlet 16 of the flow meter 2 toward the refrigerant outlet 17, and the rotor 18 rotates at an angular velocity substantially proportional to the flow velocity of the refrigerant. On the other hand, the magnetic sensor 19
Detects the change in the magnetic field caused by the rotation of the magnet in the rotor 18, converts this into a voltage signal and amplifies it to output a pulse signal. Therefore, the volume flow rate of the refrigerant flowing in the flowmeter 2 can be detected by this output.

Next, in FIG. 1, the refrigerant shortage detection device 1 is composed of a general-purpose microcomputer 22.
The output of the flow meter 2 is input to the microcomputer 22. The low temperature showcase S or the refrigerator R is further connected to the input terminal 22A of the microcomputer 22.
The temperature T output from a temperature sensor (not shown) that detects the temperature inside the refrigerator or the temperature of the cool air discharged into the refrigerator is input, and the input terminal 22B is defrosted from a microcomputer for temperature control (not shown). A signal is being input. Furthermore, the output terminal 22C of the microcomputer 22
An alarm device such as a buzzer or a display will be connected to this.

Next, the operation of the refrigerant shortage detection device 1 of the present invention having the above configuration will be described. FIG. 4 shows a microcomputer 2
2 is input to the input terminal 22A of the liquid receiver 6, for example, the temperature T in the refrigerator of the low temperature showcase S and the liquid receiver 6 output by the flowmeter 2.
3 shows the refrigerant flow rate GR on the outlet side and the defrost signal input to the input terminal 22B. In a state where no refrigerant leaks in the refrigerant circuit 9 and a predetermined amount of refrigerant is enclosed, the compressor 3 is controlled by the temperature control microcomputer to, for example, a temperature T between −3 ° C. and −5 ° C. The thermo-cycle (ON-OFF) is being operated. The flow rate GR on the outlet side of the liquid receiver 6 output by the flow meter 2 while the compressor 3 is operating is stable at about 1 liter / minute. When the defrosting of the cooler 8 is started (at this time, the defrosting signal is input to the microcomputer 22), the compressor 3
Therefore, the flow rate GR becomes zero. On the other hand, since the heater (not shown) heats up and the cooler 8 is heated, the temperature T also rises, and the defrosting ends when the temperature reaches + 10 ° C. (the defrosting signal also stops).

When the defrosting is completed, the compressor 3 is started again, so that the refrigerant starts to flow in the refrigerant circuit 9 again, but a large amount of the refrigerant is consumed in the cooler 8 at the start of the pull-down after the defrosting. The flow rate GR is relatively large at 1.5 l / min. After that, the flow rate GR gradually decreases as the temperature T decreases, and stabilizes at 1 liter / minute during the thermocycle.

When a predetermined amount of refrigerant is filled in the refrigerant circuit 9, the flow rate GR on the outlet side of the liquid receiver 6 usually shows the above-mentioned change, but there is no refrigerant leakage from the refrigerant circuit 9. When the liquid refrigerant in the receiver 6 is exhausted and flash gas is generated in the refrigerant flowing out from the receiver 6, the flow rate GR of the refrigerant from the receiver 6 is apparent as shown in the bottom of FIG. Moreover, the value rises to a value of 2.0 liters or more / minute, which is abnormally higher than the normal value (1-1.5 liters / minute). At the same time, since the predetermined cooling capacity cannot be obtained in the cooler 8,
The temperature T also becomes an extremely high value, and the inside of the refrigerator cannot cool down.

In this case, when the flow rate GR output by the flow meter 2 rises to 2 liters / minute, the microcomputer 22 determines that the refrigerant in the refrigerant circuit 9 is insufficient and outputs an output to the output terminal 22C. Then, the user is warned that the refrigerant is leaking in the refrigerant circuit 9 by the buzzer or the display. As described above, according to the refrigerant shortage detection device 1 of the present invention, when the output of the flow meter 2 provided on the outlet side of the liquid receiver 6 is input to the microcomputer 22 and the flow rate becomes a predetermined high value. Since it is determined that the refrigerant is insufficient, it is possible to quickly detect the generation of flash gas at the outlet side of the liquid receiver 6 and determine that the refrigerant is insufficient. Therefore, it is possible to detect the occurrence of cooling failure in the cooler 8 at an early stage and issue an alarm as prediction information. In particular, the refrigerant flow rate GR is directly detected and determined, and not the state of change of the temperature T alone, so the refrigerant shortage detection accuracy is improved.

Even if flash gas is generated at the outlet side of the liquid receiver 6, the interior of the low temperature showcase S may be cold in winter and the like. In this case, although the abnormality is predicted, there is no problem in practical use, and it is not necessary to issue a warning. On the other hand, the microcomputer 22 of the refrigerant shortage detection device 1 of the present invention detects the rate of decrease of the temperature T based on the temperature T from the temperature sensor input to the input terminal 22A. Then, as described above, the flow rate G
When R rises to 2 liters / minute and the rate of decrease in temperature T is slow, it is determined that the refrigerant in the refrigerant circuit 9 is insufficient,
An output is generated at the output terminal 22C.

That is, flash gas is generated and the flow rate GR
Even if the temperature rises to 2 liters / minute, the rate of decrease of the temperature T is not slow, and if the inside of the refrigerator is cold, it will not be judged as an abnormality. Therefore, it is possible to prevent substantially unnecessary alarms. You can Even when no refrigerant leaks in the refrigerant circuit 9, flash gas is likely to be generated at the outlet side of the liquid receiver 6 in the pull-down after the defrosting of the cooler 8 in some cases.

On the other hand, the microcomputer 22 prohibits the refrigerant shortage determination for a certain period after the defrosting of the cooler 8 based on the defrosting signal from the input terminal 22B. Therefore, it is possible to prevent an unnecessary alarm from being generated due to a temporary flash gas that is generated when pulling down after the defrosting.

[0025]

As described in detail above, according to the present invention, the refrigerant flow rate measuring means is provided on the outlet side of the liquid receiver of the refrigerant circuit of the refrigerator, and the control means outputs the refrigerant flow meter side means. When the flow rate reaches a predetermined high value, it is determined that the refrigerant in the refrigerant circuit is insufficient, so that it is possible to quickly detect the generation of flash gas at the outlet side of the liquid receiver and determine that the refrigerant is insufficient. Therefore, it becomes possible to detect the occurrence of poor cooling at an early stage and issue a prediction warning or the like. In particular, since the determination is made by directly detecting the flow rate of the refrigerant and not by the state of temperature change alone, it is possible to improve the refrigerant shortage detection accuracy.

According to the invention of claim 2, in addition to the invention of claim 1, a temperature detecting means for detecting the temperature of the cooled space or the temperature of the cold air supplied to the cooled space is provided, and the control means is When the flow rate output by the refrigerant flow meter side means has a predetermined high value and the rate of decrease of the temperature is slow, it is determined that the refrigerant in the refrigerant circuit is insufficient, so that flash gas is generated in winter, etc. Regardless of this, if the space to be cooled (for example, the inside of the low temperature showcase) is actually cold, it is not judged as abnormal. Therefore, it is possible to prevent generation of a substantially unnecessary alarm.

Further, according to the invention of claim 3, claim 1
In addition to the invention of the control means for a certain period after defrosting the cooler,
Since the determination of the shortage of the refrigerant is prohibited, it is possible to prevent the generation of an unnecessary alarm due to the temporary flash gas generated during the pull-down after defrosting.

[Brief description of drawings]

FIG. 1 is a block diagram of an electric circuit of a refrigerant shortage detection device of the present invention.

FIG. 2 is a refrigerant circuit diagram of a low temperature showcase and a refrigerator as an example of a refrigerator to which the present invention is applied.

FIG. 3 is a vertical sectional side view of a flow meter as a refrigerant flow rate measuring means of the present invention.

FIG. 4 is a diagram showing changes in the temperature of a space to be cooled (inside the refrigerator) and the flow rate of the refrigerant on the outlet side of the liquid receiver output by the flow meter.

[Explanation of symbols]

 1 Refrigerant shortage detection device 2 Flow meter 3 Compressor 4 Condenser 6 Liquid receiver 7 Expansion valve 8 Cooler 9 Refrigerant circuit 22 Microcomputer

Claims (3)

[Claims] 1. A refrigerator comprising a compressor, a condenser, a liquid receiver, a pressure reducing device, and a cooler, which are sequentially connected in an annular pipe to form a refrigerant circuit, which is provided on the outlet side of the liquid receiver. , A refrigerant flow rate measuring means for measuring the flow rate of the refrigerant flowing in the refrigerant circuit, and a control means for inputting the output of the refrigerant flow rate measuring means, wherein the control means controls the flow rate output by the refrigerant flow meter side means. A refrigerant shortage detection device for a refrigerator, which judges that the refrigerant in the refrigerant circuit is insufficient when a predetermined high value is reached. 2. A temperature detecting means for detecting the temperature of the cooled space or the temperature of the cool air supplied to the cooled space is provided, and the control means has a predetermined high value for the flow rate output by the refrigerant flow meter side means. The refrigerant shortage detection device for a refrigerator according to claim 1, wherein the refrigerant shortage is determined to be insufficient in the refrigerant circuit when the rate of decrease in temperature is slow. 3. The control means prohibits the refrigerant shortage determination for a certain period after defrosting the cooler.
Refrigerant shortage detection device in the refrigerator.