JPH07243727A - Refrigerator - Google Patents

Abstract

PURPOSE:To always maintain a temperature in a deep freezer constant by operating to cool at least one set of low-temperature freezing unit at the time of defrosting of one set of freezing unit in a refrigerator having two or more sets of low-temperature freezing units. CONSTITUTION:When frosting of an evaporator 23 of a first low-temperature freezing unit 1 is, as the unit 1 is, for example, operated to be cooled and a second low-temperature unit is paused according to an installation position in a deep freezer 4 of the unit, an error of a temperature detector 34, etc., detected by a frost detector 37, the unit 1 starts to be defrosted and a second low-temperature freezing unit 2 starts to cool. That is, a refrigerant liquid supply valve 16 of a high-temperature freezing unit 3 is opened, and a compressor 23 of the unit 2 is operated. In this case, if a blower 25 of the unit 2 is not operated, it is also operated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerating apparatus using two or more sets of low temperature refrigerating units, and more particularly to a refrigerating apparatus which avoids an increase in internal cold storage temperature during defrost operation.

[0002]

2. Description of the Related Art The evaporator of a freezer has frost formation because the temperature inside the freezer is low, and it is necessary to perform a defrost operation to remove this frost. When performing the defrost operation, the four-way switching valve is switched to send high-pressure, high-temperature refrigerant gas to the evaporator to melt part of the frost.

In a large freezer, Japanese Unexamined Patent Publication No. 5-18647
As shown in (2), the dual refrigeration / refrigeration system is frequently used, and a method is used in which one set of the high temperature refrigeration unit and the low temperature refrigeration unit are thermally coupled by a cascade condenser. In this case, the defrost operation time is shortened by utilizing the heat energy of the refrigerant of the high temperature refrigeration unit.

[0004]

The low temperature refrigeration unit is
It is more efficient to provide two or more smaller ones than one large one because it is efficient to operate only one set and freeze the rest when the freezing load is low in winter etc. It is equipped with two or more sets of low temperature refrigeration units. However, when the operating low temperature refrigeration unit enters the defrost operation, cooling stops and the temperature inside the refrigerator rises. When the temperature inside the refrigerator rises to a certain degree, the low temperature refrigeration unit that is at rest detects this and operates, but it takes time until the low temperature refrigeration unit during rest enters into steady operation, during which the temperature inside the refrigerator rises. There is a problem such as doing.

An object of the present invention is to provide a refrigerating apparatus which keeps the temperature inside the freezer always constant.

[0006]

SUMMARY OF THE INVENTION The present invention is directed to a compressor 20,
In a refrigerating apparatus including a condenser 21, an expansion valve 22, an evaporator 23, and two or more low temperature refrigeration units capable of switching between cooling operation and defrost operation, one low temperature refrigeration unit enters defrost operation and the rest. When at least one set of low-temperature refrigeration units of 1) is in operation stop, at least one set of low-temperature refrigeration units in operation stop is cooled.

Further, according to the present invention, the condenser 21 of the low temperature refrigeration unit of each set includes a compressor 10, a condenser 11 and an expansion valve 1.
2. Evaporator 1 of high temperature refrigeration unit 3 including evaporator 13
It is characterized in that it is cooled by a cascade condenser 28 that is thermally coupled to the No. 3.

Further, the present invention is characterized in that the cascade condensers 28 of the refrigerating units of each set are connected in parallel to the refrigerant pipe of the high temperature refrigerating unit 3 and the refrigerant pipe of the low temperature refrigerating unit, respectively.

Further, the present invention is characterized in that the condenser 21 of the low temperature refrigeration unit of each set dissipates heat of condensation to the atmosphere by the blower 29.

Further, according to the present invention, the low temperature refrigeration unit of each set detects the temperature inside the refrigerator for each group, and the temperature inside the refrigerator is set to TH for each group.
It is characterized in that it is operated so as to be controlled to 1.

[0011]

According to the present invention, in a refrigerating apparatus comprising two or more low temperature refrigerating units, one low temperature refrigerating unit is in defrost operation, and the remaining at least one low temperature refrigerating unit is not in operation. At this time, at least one set of the low temperature refrigeration unit that is not in operation enters the cooling operation. As a result, the inside of the freezer is always kept at a constant temperature.

Even if the condenser 21 of the low temperature refrigeration unit is a binary refrigeration apparatus in which the condenser 21 of the low temperature refrigeration unit is thermally coupled to the evaporator 13 of the high temperature refrigeration unit 3 by the cascade condenser 28, the condenser 21 of the low temperature refrigeration unit is Blower 29
It may be a unit refrigerating device that dissipates the heat of condensation to the atmosphere.

The cascade condenser 28 preferably has a structure in which the refrigerant tubes of the high temperature refrigeration unit 3 and the refrigerant tubes of the low temperature refrigeration unit are connected in parallel.

When all the low temperature refrigerating units are operated to control the temperature inside the refrigerator to TH1, and when the refrigerating load is small in winter etc., only one set of the low temperature refrigerating units, such as the low temperature refrigerating unit near the inlet, is operated. When it is operated and enters the defrost operation, at least one set of the remaining low temperature refrigeration units is cooled. This prevents all low-temperature refrigeration units in the freezer from stopping operation (including defrost operation).

By operating the low-temperature refrigeration unit in this manner, a certain low-temperature refrigeration unit is switched to the defrost operation, and it is detected that the internal temperature rises and the other low-temperature refrigeration units are cooled. Compared with a refrigeration system, the temperature inside the refrigerator can be kept constant.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a refrigerant piping system diagram of an embodiment of the present invention, and FIG. 2 shows a layout of equipment. The evaporator 23 of each of the plurality of low temperature refrigeration units such as the first low temperature refrigeration unit 1 and the second low temperature refrigeration unit 2 is installed in the freezer 5. The configuration of the low temperature refrigeration unit is the first refrigeration unit 1
Since the second refrigeration unit 2 is the same, the first refrigeration unit 1 will be described below. The high-temperature (for example, 25 ° C.) refrigerant vapor compressed by the compressor 20 enters the cascade condenser 28 through the four-way switching valve 27 as indicated by the solid arrow. Here, the condenser 21 of the low temperature refrigeration unit 1 is thermally coupled to the evaporator 13 of the high temperature refrigeration unit 3,
The refrigerant vapor of the low temperature refrigeration unit 1 is cooled to, for example, 15 ° C. and condensed. The liquefied refrigerant liquid enters the freezer 5 through the check valve 24, is decompressed by the expansion valve 22, is supplied to the evaporator 23, and cools the air sent by the blower 25 in the freezer 5 to, for example, −45 ° C. , The refrigerant is, for example, -50
The gas is vaporized at ℃ and is sucked into the compressor 20 through the four-way switching valve 27. Since this embodiment is a binary refrigeration system, the high-temperature refrigeration unit 3 is provided outside the freezer 5, and the high-temperature (for example, 60 ° C.) refrigerant vapor compressed by the compressor 10 heats the air sent by the blower 14. For example 45
It is liquefied at ℃, decompressed by the expansion valve 12, and sent to the cascade condenser 28 of the low temperature refrigeration unit such as the first low temperature refrigeration unit 1 and the second low temperature refrigeration unit 2. Here, the refrigerant of the high temperature refrigeration unit 3 is heated to, for example, 5 ° C. and vaporized, and conversely, the refrigerant of the low temperature refrigeration unit 1 is cooled to 15 ° C. and liquefied. The vaporized refrigerant of the high temperature refrigeration unit 3 is sucked into the compressor 10.

The temperature inside the freezer is detected by a temperature detector 34 provided near the cold air outlet of each low temperature refrigeration unit,
This is controlled to be TH1 (for example, −45 ° C.). That is, when the temperature becomes −45 ° C. or lower, the compressor 20 is stopped and the supply valve 15 for sending the refrigerant liquid of the high temperature refrigeration unit 3 to the cascade condenser 28 is closed. The blower 25 of the low-temperature refrigeration unit may be continuously operated to keep the temperature inside the freezer 5 constant, or may be stopped to prevent heat generation due to the operation of the blower 25. It is determined in consideration of the size of the freezer 5 and the amount of articles stored.

Depending on the installation position of the low temperature refrigeration unit in the freezer 5, the temperature difference of the temperature detector 34, etc., for example, the first
When the refrigerating unit 1 of No. 1 performs the cooling operation and the second low temperature unit is at rest, when it is detected by the frost detector 37 that the evaporator 23 of the first low temperature refrigerating unit 1 has frosted, The first low-temperature refrigeration unit 1 enters the defrosting operation described later, and the second low-temperature refrigeration unit 2 enters the cooling operation. That is, the refrigerant liquid supply valve 16 of the high temperature refrigeration unit 3 is opened and the compressor 23 of the second low temperature refrigeration unit 2 is operated. In this case, if the blower 25 of the second low temperature refrigeration unit 2 is not operating, it is also operating.

When the first low temperature refrigeration unit 1 starts the defrost operation, the refrigerant liquid supply valve 1 of the high temperature refrigeration unit 3
5 is closed, the four-way switching valve 27 of the first refrigeration unit 1 is switched to pass through the flow path indicated by the dotted line, and the operation of the blower 25 is stopped. During the defrost operation, the high-temperature (for example, 25 ° C.) refrigerant vapor compressed by the compressor 20 enters the evaporator 23 through the four-way switching valve 27 as indicated by the dotted arrow, and part of the frost is formed. The refrigerant vapor is liquefied by melting and dropping. The refrigerant liquid passes through the check valve 30 provided in parallel with the temperature-sensitive expansion valve 22, is decompressed by the resistance pipe 31, is heated by the remaining refrigerant liquid in the high temperature refrigeration unit 3 of the cascade condenser 28, is vaporized, and is compressed. The machine 20 is sucked.
If the frost detector 37 detects that there is no frost,
The first low temperature refrigeration unit 1 is returned to the cooling operation, and the operation of the second low temperature refrigeration unit 2 is stopped.

FIG. 3 is a flow chart showing the operation control mode in the control circuit of this embodiment. Such a control circuit is realized by a microcomputer or the like. The cooling operation is started in step n1, the first low temperature refrigeration unit 1, the second low temperature refrigeration unit 2 and the high temperature refrigeration unit 3 are operated in step n2, and the temperature in the freezer 5 is lowered. In step n3, the temperature of the cold air outlet of each low temperature refrigeration unit is detected by each temperature detector 34, and for example, the second
Temperature T2 detected by the temperature detector 342 of the low temperature refrigeration unit 2 of
It is determined whether the temperature T1 is lower than the temperature T1 detected at 1 and the temperature T2 is lower than a preset temperature TH1.
If TH1 is achieved, the process proceeds to step n4, and if this is not achieved, the process returns to step n2. In step n4, it is determined that T1 ≧ TH1, and if T1 ≧ TH1, the process proceeds to step n6, and if T1 <TH1, the process proceeds to step n5, where the first low temperature refrigeration unit 1, the second low temperature refrigeration unit 2 and the high temperature refrigeration Stop Unit 3, step n4
Return to. In step n6, the first low temperature refrigeration unit 1 is cooled and the second low temperature refrigeration unit 2 is stopped. Next, at step n7, the frost detector 37 determines whether or not there is frost on the evaporator 23. If frost is present, the process proceeds to step n8, and if there is no frost, the process returns to step n5. Step n8
Then, the first low temperature refrigeration unit 1 is switched to the defrost operation, and at the same time, the second low temperature refrigeration unit 2 is cooled. Next, in step n9, it is judged by the frost detector 37 whether or not frost is no longer detected. If frost is no longer detected, the process returns to step n3 and the following steps are repeated until the cooling operation is stopped. If frost formation is detected, the process returns to step n8.

Even if the pressure detector 35 detects a decrease in the pressure at the inlet of the compressor 10 of the high temperature refrigeration unit 3 due to a decrease in the number of operating low temperature refrigeration units, and the load on the compressor 10 is reduced by opening the bypass valve 36. Good. Further, in order to compensate for the insufficient capacity of the high temperature refrigeration unit 3 at the beginning of the refrigeration operation, the temperature of the refrigerant liquid of the low temperature refrigeration unit 1 at the outlet of the cascade condenser 28 is detected by the temperature detector 38, and the blower 39 is kept until the temperature falls below a certain temperature. You may drive.

The temperature in the freezer 5 is controlled to TH1 by the low temperature freezing unit, and when the refrigerating load is low such as in winter, one set of low temperature freezing unit near the inlet of the freezer 5 is operated, and when it is frosted, it remains. One of the low temperature refrigeration units may be always cooled.

FIG. 4 shows a refrigerant piping system diagram of another embodiment of the present invention. Although the configuration of the present embodiment is a unit refrigeration system, the low-temperature refrigeration unit is similar to the configuration shown in FIG. 1, and corresponding parts are designated by the same reference numerals. It should be noted that the condenser 21 is cooled by the air sent by the blower 19 and the refrigerant vapor is liquefied. Thereby, the high temperature refrigerating unit is not required and the configuration is simplified, but since the condenser 21 is cooled by the atmosphere, its temperature is limited, and it is difficult to lower the temperature of the evaporator 23, that is, the temperature in the freezer 5. Therefore, the unit refrigeration system is used in a freezer at about -15 ° C. On the other hand, the above-mentioned binary freezer is used for a freezer having a temperature of about -45 ° C or lower. The operation of the control circuit of this embodiment is also substantially the same as that described with reference to FIG. 3, but the high temperature refrigeration unit is not operated because it is a unit refrigeration system.

As the cascade condenser 28, it is preferable that the refrigerant pipe (evaporator 11) of the high temperature refrigeration unit 3 and the refrigerant pipe (condenser 21) of the low temperature refrigeration unit 3 are provided in parallel as shown in FIG.

[0025]

As described above, according to the present invention, at least one remaining low temperature refrigerating unit performs the cooling operation during the defrosting operation of one low temperature refrigerating unit. Can be kept constant at all times.

[Brief description of drawings]

FIG. 1 is a refrigerant piping system diagram of a binary refrigeration system that is an embodiment of the present invention.

FIG. 2 is a layout view of devices.

FIG. 3 is a flowchart showing an aspect of operation control in a control circuit.

FIG. 4 is a refrigerant piping system diagram of a unit refrigeration system that is another embodiment of the present invention.

FIG. 5 is a cascade condenser 2 used in a dual refrigeration system.
8 is an example.

[Explanation of symbols]

 1 1st low temperature freezing unit 2 2nd low temperature freezing unit 3 high temperature freezing unit 5 freezer 13 high temperature freezing unit evaporator 20 low temperature freezing unit compressor 21 low temperature freezing unit condenser 22 low temperature freezing unit thermal expansion valve 23 Evaporator of low temperature refrigeration unit 27 Four-way switching valve 28 Cascade condenser 29 Blower for condensation of low temperature refrigeration unit

Claims (5)

[Claims] 1. A compressor 20, a condenser 21, an expansion valve 22,
In a refrigerating device comprising an evaporator 23 and two or more low temperature refrigeration units capable of switching between cooling operation and defrost operation, one low temperature refrigeration unit enters defrost operation and the remaining at least one low temperature refrigeration unit. When the operation is stopped, at least one set of the low temperature refrigeration unit in the stopped operation is cooled and operated. 2. The condenser 2 of the low temperature refrigeration unit of each set.
1 is a compressor 10, a condenser 11, an expansion valve 12, and an evaporator 1.
The refrigerating apparatus according to claim 1, wherein the refrigerating apparatus is cooled by a cascade condenser 28 that is thermally coupled to the evaporator 13 of the high temperature refrigerating unit 3 including the cooling condenser 3. 3. The cascade condenser 28 of each refrigeration unit of each set is connected in parallel to the refrigerant pipe of the high temperature refrigeration unit 3 and the refrigerant pipe of the low temperature refrigeration unit, respectively. Refrigeration equipment. 4. The condenser 2 of the low temperature refrigeration unit of each set.
The refrigerating apparatus 1 according to claim 1, wherein the blower 29 dissipates the heat of condensation into the atmosphere. 5. The low temperature refrigerating unit of each set is operated to detect the internal cold storage temperature for each set and to control the internal cold storage temperature to TH1 for each set. Either one
Refrigerating apparatus according to paragraph.