JP2002081807A - Refrigerating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve reliability of a compressor by reducing the number of revolutions of defrosting operation, in a refrigerating device having a plurality of outdoor heat exchangers. SOLUTION: Temperature sensors (31 and 32) are mounted on first and second heat exchangers (14 and 20). When the detecting temperature of the temperature sensor (31 or 32) is decreased to a value lower than a first given temperature, it is decided that frosting occurs. An electronic expansion valve (16 or 17) corresponding to the outdoor heat exchanger (14 or 20) to which frosting occurs is closed and a feed of a refrigerant is stopped with outdoor air fed to the outdoor heat exchanger (14 or 20). This constitution melts frost on the outdoor heat exchanger (14 or 20) with heating operation continued.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a refrigeration system,
In particular, it relates to defrosting of an outdoor heat exchanger.

[0002]

2. Description of the Related Art In a refrigerating apparatus having an indoor heat exchanger and an outdoor heat exchanger, the refrigerant is condensed by the indoor heat exchanger and evaporated by the outdoor heat exchanger. Depending on the evaporation temperature and the outside air condition, frost may be formed on the outdoor heat exchanger. However, when frost is formed, the heat exchange capacity of the outdoor heat exchanger is significantly reduced.Therefore, if the heating operation is continued while the frost is formed, the low pressure side pressure of the refrigerant circuit may be excessively reduced or the compressor may not be operated. Liquid backing may occur. Therefore, conventionally, when frost is formed on the outdoor heat exchanger, a defrosting operation for melting the frost is performed. For example, there is known a reverse cycle defrost type defrosting operation in which the circulation direction of the refrigerant in a refrigerant circuit is switched and high-temperature gas refrigerant flows through an outdoor heat exchanger to melt frost.

[0003] Conventionally, refrigeration systems in which a plurality of outdoor heat exchangers are provided in parallel in a refrigerant circuit, such as a so-called multi-type refrigeration system, are often used. In such a refrigerating apparatus, the defrosting operation is started when any one of the outdoor heat exchangers is frosted or when all the outdoor heat exchangers are frosted.

[0004]

However, since these outdoor heat exchangers are installed at different locations, the outside air conditions and the like for each heat exchanger are not uniform. For this reason, some heat exchangers are susceptible to frost, while others are difficult to frost. As described above, when the defrosting operation is started at the time when any one of the heat exchangers is frosted, the defrosting operation will be performed frequently, with the result that the number of defrosting operations is unnecessarily increased. Become. On the other hand, if the defrosting operation is started when all the heat exchangers have formed frost, the defrosting operation is not performed until the heat exchanger that is difficult to form frost forms frost. Defrosting is not performed until a large amount of frost is formed, and the ability cannot be sufficiently exhibited. Therefore, in the conventional method, since the defrosting operation is frequently repeated, the reliability of the compressor is reduced, or the efficiency of the refrigeration system is reduced.

[0005] The present invention has been made in view of the above points, and an object thereof is to improve the reliability of a compressor and the efficiency of a refrigeration system by reducing the frequency of defrosting operation. It is in.

[0006]

In order to achieve the above object, the present invention provides a method for detecting a frost on only a part of an outdoor heat exchanger, the refrigerant being supplied to the outdoor heat exchanger while the heating operation is continued. The supply was stopped, and the frost of the outdoor heat exchanger was melted by the blown outdoor air.

Specifically, the refrigeration apparatus according to the present invention comprises a plurality of outdoor heat exchangers provided in parallel in a refrigerant circuit.
(14, 20) and each of the outdoor heat exchangers (14, 20), each of which is openable and closable to supply a refrigerant to each of the outdoor heat exchangers (14, 20) during the heating operation. Means (16, 17) and a blower for supplying outdoor air to the outdoor heat exchangers (14, 20)
(15, 21) and a refrigeration apparatus including frost detection means (31, 32) for detecting frost formation of the outdoor heat exchangers (14, 20),
When detecting frost formation only on some outdoor heat exchangers (14; 20),
Decompression means (16; 1) corresponding to the frosted outdoor heat exchanger (14; 20)
7) is closed, and the frost of the outdoor heat exchanger (14; 20) is melted by the air supplied from the blower (15; 21).

According to the above, when frost formation is detected only in a part of the outdoor heat exchanger, the decompression means corresponding to the frosted outdoor heat exchanger is closed. No coolant is supplied. However, outdoor air is supplied to this outdoor heat exchanger by a blower. Therefore, since the refrigerant does not evaporate in the outdoor heat exchanger, the frost in the outdoor heat exchanger is heated and melted by the outdoor air. On the other hand, since the decompression means corresponding to the outdoor heat exchanger that is not frosted is not closed, the supply of the refrigerant to the outdoor heat exchanger is continued. Therefore, it is not necessary to interrupt the heating operation to defrost only some of the outdoor heat exchangers, and it is sufficient to perform the defrosting operation such as reverse cycle defrost only when all the outdoor heat exchangers have formed frost. . Accordingly, the frequency of the defrosting operation can be reduced, and the reliability of the compressor and the efficiency of the refrigeration system can be improved.

The frost detection means includes an outdoor heat exchanger (14,
The temperature sensor (31, 32) provided in (20) may be provided to detect frost formation based on the temperature detected by each of the temperature sensors (31, 32).

Since the temperature sensor is easy to handle and inexpensive, the use of such a temperature sensor makes it possible to implement the frost detection means with a simple and inexpensive configuration.

The refrigerating apparatus includes an outside air temperature sensor (33, 34) for detecting the temperature of the outdoor air, and the frost detection means includes a temperature sensor (31, 34) provided in the outdoor heat exchanger (14, 20). 32) detecting the occurrence of frost when the detected temperature is lower than the first predetermined temperature, and depressurizing means corresponding to the frosted outdoor heat exchanger (14; 20) when detecting the occurrence of frost. (16; 17) is closed, and then the difference between the outdoor air temperature and the temperature detected by the temperature sensor (31; 32) provided in the outdoor heat exchanger (14; 20) is the second.
When the temperature is lower than the predetermined temperature, the pressure reducing means (16; 17) may be opened.

Thus, when the temperature of the outdoor heat exchanger becomes lower than the first predetermined temperature, it is determined that frost has occurred, the corresponding pressure reducing means is closed, and the above-described defrosting is performed. On the other hand, when defrosting progresses and the difference between the outdoor air temperature and the temperature of the outdoor heat exchanger becomes smaller than the second predetermined temperature, it is determined that the frost of the outdoor heat exchanger has melted, and the pressure reducing means is opened. . As a result, the defrosted outdoor heat exchanger immediately resumes the heat exchange operation.

[0013]

As described above, according to the present invention, when the frost formation on only some of the outdoor heat exchangers is detected, the supply of the refrigerant to the outdoor heat exchangers is stopped, and the frost is removed by the blown outdoor air. Therefore, the outdoor heat exchanger can be defrosted while the heating operation is continued. Therefore, the frequency of the defrosting operation can be reduced, and the reliability of the compressor and the operation efficiency of the device can be improved.

If frost formation is detected based on the temperature detected by the temperature sensor provided in the outdoor heat exchanger, frost formation on the outdoor heat exchanger can be detected with a simple and inexpensive configuration.

When the temperature detected by the temperature sensor provided in the outdoor heat exchanger is lower than the first predetermined temperature, it is determined that frost has occurred, and the difference between the outdoor air temperature and the temperature detected by the temperature sensor is determined as the second temperature. When the temperature becomes lower than the predetermined temperature, it is determined that the defrosting is completed, so that the frost formation state of the outdoor heat exchanger can be grasped with a simple configuration. In addition, if the decompression means that was closed after the defrosting is completed is opened, the defrosted outdoor heat exchanger can immediately resume the heat exchange operation, and the efficiency of the heating operation accompanying the defrosting can be improved. The decrease can be suppressed.

[0016]

Embodiments of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, a refrigeration apparatus according to an embodiment of the present invention has a multi-type air system including a plurality of outdoor units (2, 3) and a plurality of indoor units (4, 4,...). Harmony equipment
(1). The indoor units (4, 4, ...) are connected to the outdoor units (2, 3) via refrigerant pipes (5, 6). Each indoor unit (4) has an electronic expansion valve (7) and an indoor unit. A heat exchanger (8) is provided.

As shown in FIG. 2, the first outdoor unit (2)
Inside, there are a compressor (11, 12), a four-way switching valve (13), a first outdoor heat exchanger (14), a first outdoor blower (15), a first electronic expansion valve.
(16), a second electronic expansion valve (17), a liquid receiver (18), and an accumulator (19) are provided. Inside the second outdoor unit (3), a second outdoor heat exchanger (20) and a second outdoor blower (2
1) is provided.

The first port of the four-way switching valve (13) is connected to the compressor (11,
The second port is connected to the refrigerant pipe (23), and the second port is connected to the discharge pipe (22). The refrigerant pipe (23) is branched, one branch pipe is connected to one end of the first outdoor heat exchanger (14), and the other branch pipe is connected to one end of the second outdoor heat exchanger (20). . The other end of the first outdoor heat exchanger (14) is connected to a first electronic expansion valve (16) via a refrigerant pipe (24). The other end of the second outdoor heat exchanger (20) is connected to a second electronic expansion valve (17) via a refrigerant pipe (25). The refrigerant pipe (26) connected to the first electronic expansion valve (16) and the refrigerant pipe (27) connected to the second electronic expansion valve (17) merge and are connected to the liquid receiver (18). I have. Refrigerant piping (6) connected to indoor units (4, 4, ...)
Is connected to the fourth port of the four-way switching valve (13). The third port of the four-way switching valve (13) is connected to the suction pipe (28) of the compressor (11, 12). The suction side pipe (28) is provided with an accumulator (19). The compressor (11,
An oil separator (29, 29) is provided on the discharge side of (12).

Thus, the first outdoor heat exchanger (14) and the second outdoor heat exchanger (14)
The outdoor heat exchanger (20) has a positional relationship parallel to each other on the refrigerant circuit. The first electronic expansion valve (16) is provided corresponding to the first outdoor heat exchanger (14), and the second electronic expansion valve (17) is
It is provided corresponding to the outdoor heat exchanger (20). That is,
The electronic expansion valve is provided for each outdoor heat exchanger. These electronic expansion valves (16, 17) can be controlled to the full degree, as well as being able to control the opening degree, and correspond to the "openable and closable pressure reducing means" in the present invention. The "openable and closable pressure reducing means" is not limited to the electronic expansion valve as long as it has both the function of opening and closing the refrigerant flow path and the function of reducing the pressure of the refrigerant. For example, a combination of an on-off valve (for example, an electromagnetic valve or the like) and a throttle mechanism (a capillary tube or the like) may be used.

A bypass pipe (50) is provided between the discharge pipe (22) and the suction pipe (28). Bypass pipe (50)
Is provided with a solenoid valve (54), on the downstream side of which three branch pipes
(51,52,53). The branch pipes (51, 52, 53) are respectively connected to the suction side pipes (28). This bypass pipe
(50) is to open the solenoid valve (54) to return the high-pressure refrigerant to the suction-side pipe (28) when the low-pressure side pressure becomes equal to or lower than a predetermined value, thereby preventing an excessive decrease in the low-pressure side pressure. Thus, the downstream side of the bypass pipe (50) is connected to the three branch pipes (51, 5).
By branching to (2, 53), the amount of refrigerant flowing per bottle is reduced, so that the passing sound of the refrigerant can be reduced.

The first outdoor heat exchanger (14) and the second outdoor heat exchanger (20) are provided with temperature sensors (31, 32), respectively. The temperature sensor (31) is provided at a position on the first electronic expansion valve (16) side of the first outdoor heat exchanger (14), and the temperature sensor (32) is connected to the second electronic heat exchanger (20) of the second outdoor heat exchanger (20). It is provided at a position on the side of the expansion valve (17). The first outdoor unit (2) and the second outdoor unit (3) are provided with outside air temperature sensors (33, 34) for detecting the temperature of the outdoor air, respectively. These temperature sensors (31, 32, 33, 34) are connected to the controller (40).

Next, the operation of the air conditioner (1) will be described.

During the cooling operation, the four-way switching valve (13) is set in a state where the first port and the second port communicate with each other, and the third port and the fourth port communicate with each other. The refrigerant is supplied to the compressor (1
After being discharged from (1,12), it is condensed in the outdoor heat exchanger (14,20) and decompressed by the electronic expansion valves (7,7, ...).
Evaporate at (8,8, ...) and return to the compressor (11,12).

During the heating operation, the four-way switching valve (13) is set in a state where the first port and the fourth port communicate with each other, and the second port and the third port communicate with each other. As shown by the solid arrows in FIG. 3, the refrigerant is discharged from the compressors (11, 12) and then condensed in the indoor heat exchangers (8, 8,.
After returning to the first outdoor unit (2) through (5), the refrigerant piping
(26) and the refrigerant pipe (27). The divided refrigerant is decompressed by the electronic expansion valves (16, 17), further evaporated in the outdoor heat exchangers (14, 20), and then sucked into the compressors (11, 12).

During the heating operation, frost may be formed on the outdoor heat exchangers (14, 20) depending on the outside air condition and the like.
In the present air conditioner (1), frost formation is detected based on the temperature detected by the temperature sensors (31, 32) provided in the outdoor heat exchangers (14, 20). Specifically, when the temperature detected by the temperature sensors (31, 32) becomes lower than a first predetermined temperature at which a certain amount of frost is estimated to have occurred, it is determined that frost has occurred.

The first outdoor unit (2) and the second outdoor unit (2)
Depending on the location of the outdoor unit (3), one of the two outdoor heat exchangers (14, 20) may be more susceptible to frost than the other. In such a case, for example, if the first outdoor heat exchanger (14) is more susceptible to frost than the second outdoor heat exchanger (20), it is attached to the first outdoor heat exchanger (14). While the detected temperature of the temperature sensor (31) is lower than the first predetermined temperature, the detected temperature of the temperature sensor (32) attached to the second outdoor heat exchanger (20) is equal to or higher than the first predetermined temperature. Sometimes. In such a case, the first outdoor heat exchanger
It is determined that frost has occurred only in (14).

As described above, when only one of the outdoor heat exchangers (14) is frosted, the heating operation is continued as follows, and the removal of the frosted outdoor heat exchanger (14) is continued. Do the frost. That is, when only the first outdoor heat exchanger (14) is frosted, the controller (40) closes the first electronic expansion valve (16) corresponding to the first outdoor heat exchanger (14). As a result, as shown in FIG. 4, the second outdoor heat exchanger (20) free from frost formation
While the refrigerant continues to be supplied to the first outdoor heat exchanger (14) where the frost has formed, the refrigerant is not supplied to the first outdoor heat exchanger (14). for that reason,
Since the refrigerant does not evaporate in the first outdoor heat exchanger (14), the frost generated in the first outdoor heat exchanger (14) is gradually melted by the outdoor air. Thus, the first outdoor heat exchanger (14) is defrosted. On the other hand, the refrigerant is continuously supplied to the second outdoor heat exchanger (20) in which frost is not generated, so that the evaporation of the refrigerant is continued and the heating operation is continued. It should be noted that if the outdoor air temperature is too low, the time required for defrosting becomes long, so the above defrosting operation may be performed only when the outdoor air temperature is equal to or higher than a predetermined temperature. For example, the detected temperature of the outside air temperature sensor (33, 34) is 10 ° C.
The above-described defrosting operation may be performed only at the time described above, and when the temperature is lower than 10 ° C., the heating operation may be interrupted to execute the reverse cycle defrost type defrosting operation.

Next, the defrosting of the first outdoor heat exchanger (14) proceeds, and the detected temperature of the outside air temperature sensor (33) and the temperature sensor (31)
When the difference from the detected temperature becomes smaller than the second predetermined temperature (for example, 5 ° C.), it is determined that the frost generated in the first outdoor heat exchanger (14) is melted. Then, the first electronic expansion valve (16) is opened, and thereafter, as before the detection of the frost formation, the opening is controlled to an opening suitable for the heating operation.

On the other hand, when all the outdoor heat exchangers, that is, both the first outdoor heat exchanger (14) and the second outdoor heat exchanger (20) are frosted, the above-described defrosting is performed. The operation is not performed, the heating operation is interrupted, and then the same reverse cycle defrost type defrosting operation as that of the related art is performed.

As described above, in the air conditioner (1), when only one of the outdoor heat exchangers (14 or 20) is frosted, the electronic device corresponding to the outdoor heat exchanger (14 or 20) is not frosted. The expansion valve (16 or 17) was closed. Therefore, the supply of the refrigerant can be stopped while the outdoor air is continuously supplied to the outdoor heat exchanger (14 or 20). As a result, the frosted outdoor heat exchanger (14 or 20) is heated by the outdoor air, while the unfrosted outdoor heat exchanger (2
Since the heat exchange operation of 0 or 14) is continued, it is possible to defrost only the frosted outdoor heat exchanger (14 or 20) while continuing the heating operation. Therefore, since the defrosting operation only needs to be performed when all the outdoor heat exchangers (14 and 20) are frosted, the interval between the defrosting operations can be longer than before, and the reliability of the compressor can be improved. Can be improved.

Since the presence or absence of frost is determined based on the temperature detected by the temperature sensors (31, 32) attached to the outdoor heat exchangers (14, 20), frost formation can be detected with a simple and inexpensive configuration. can do.

Since the completion of defrosting is detected based on the difference between the outdoor air temperature and the temperature of the outdoor heat exchangers (14, 20), the completion of defrosting can be detected with a simple and inexpensive configuration. Can be.

In the above embodiment, two outdoor heat exchangers are provided. However, the refrigeration apparatus according to the present invention may of course include three or more outdoor heat exchangers. . In the embodiment in which n outdoor heat exchangers are provided (n is a natural number of 3 or more), the defrosting operation is executed only when all the outdoor heat exchangers are frosted, and n-1 or less outdoor heat exchangers are used. When only the exchanger is frosted, the heating operation is continued after closing the electronic expansion valve corresponding to the outdoor heat exchanger in which frost has occurred, as in the above embodiment.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an air conditioner according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of an outdoor unit.

FIG. 3 is a diagram showing a flow of a refrigerant during a heating operation in an outdoor unit.

FIG. 4 is a diagram illustrating a flow of a refrigerant when only a first outdoor heat exchanger is frosted during a heating operation.

[Explanation of symbols]

 (1) Air conditioner (2) First outdoor unit (3) Second outdoor unit (4) Indoor unit (11,12) Compressor (13) Four-way switching valve (14) First outdoor heat exchanger (15 , 21) Outdoor blower (16) First electronic expansion valve (17) Second electronic expansion valve (20) Second outdoor heat exchanger (31,32) Temperature sensor (33,34) Outside air temperature sensor

 ──────────────────────────────────────────────────の Continued on the front page (72) Keiichi Yamamoto, Inventor 1304, Kanaokacho, Sakai-shi, Osaka Daikin Industries, Ltd. Inside the Sakai Seisakusho Kanaoka Plant (72) Inventor Tsuyoshi Yamada 1304, Kanaokacho, Sakai-shi, Osaka Daikin Industries, Ltd. Sakai Plant Kanaoka Factory

Claims (3)

[Claims] 1. A plurality of outdoor heat exchangers (14, 20) provided in parallel with each other in a refrigerant circuit, provided for each of the outdoor heat exchangers (14, 20),
Depressurizing the refrigerant during the heating operation to reduce the temperature of each outdoor heat exchanger (14, 20)
Open / close pressure reducing means (16, 17) for supplying air to the outdoor heat exchangers (14, 20), a blower (15, 21) for supplying outdoor air to the outdoor heat exchangers (14, 20), and the outdoor heat exchangers (14, 20). ) Is a refrigeration apparatus equipped with frost detection means (31, 32) for detecting frost formation, when detecting frost formation on only some of the outdoor heat exchangers (14; 20),
Decompression means (16; 1) corresponding to the frosted outdoor heat exchanger (14; 20)
A refrigeration system that closes 7) and melts the frost of the outdoor heat exchanger (14; 20) with air supplied from the blower (15; 21). 2. The refrigeration apparatus according to claim 1, wherein the frost detection means includes temperature sensors (31, 32) provided in each of the outdoor heat exchangers (14, 20). 31, 32) a refrigeration apparatus configured to detect frost formation based on the detected temperature. 3. The refrigeration apparatus according to claim 2, further comprising an outside air temperature sensor (33, 34) for detecting the temperature of the outdoor air, wherein the frost detection means is provided in the outdoor heat exchanger (14, 20). When the detected temperature of the detected temperature sensor (31, 32) becomes lower than the first predetermined temperature, it is configured to detect the occurrence of frost, and when the occurrence of frost is detected, the outdoor heat exchanger (14; 20)
Is closed, and then the difference between the outdoor air temperature and the temperature detected by the temperature sensor (31; 32) provided in the outdoor heat exchanger (14; 20) is equal to the second temperature. A refrigerating device that opens the pressure reducing means (16; 17) when the temperature becomes lower than a predetermined temperature;