JP3324380B2 - Refrigeration equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerating apparatus used in a refrigerant circuit of a freezer, and more particularly to a countermeasure for recovering frost that separates and drops from an evaporator during a defrosting operation.

[0002]

2. Description of the Related Art Conventionally, a refrigerating apparatus used in a refrigerant circuit of a freezer as disclosed in, for example, Japanese Patent Application Laid-Open No. H5-5567 has a refrigerating operation for cooling the inside of the freezer and a refrigerating operation in an evaporator. A defrosting operation for melting the formed frost is performed. That is, when frost forms on the evaporator, high-temperature and high-pressure discharge gas from the compressor is supplied to the evaporator to melt the frost and collect it as drain water in a drain pan disposed below the evaporator. Like that.

FIG. 7 shows a refrigerator unit of this type.
(a) shows the vicinity of the portion where the evaporator (b) is provided.
The evaporator (b) is disposed in the unit casing (c) in the vicinity of the suction port (d), and has a drain pan (e) disposed below. A fan (g) is provided near the outlet (f) of the casing (c).
By driving (g), air flows from the suction port (d) toward the blowout port (f) (see arrow A in FIG. 7), and the air flows into the evaporator (b).
When passing through, heat is exchanged with the refrigerant. In general, as shown in FIG. 7, a large amount of the frost (h) is generated in the upstream portion of the evaporator (b) in the air flow.

[0004]

By the way, in the above-described defrosting operation, especially in a situation where the amount of frost is large and the circulation amount of the refrigerant for defrosting is large, FIG. Thus, only melting around the refrigerant pipe of the evaporator (b) is promoted, and frost (h) is released from the refrigerant pipe.

[0005] Therefore, as shown by the dashed line in FIG. 7 (b), the frost (h ′) that has not yet been melted forms a lump and forms an evaporator (b).
From the air inlet (d) side.
(h ') could not be collected in the drain pan (e). In particular, this phenomenon is likely to occur when the height of the evaporator (b) is large.

The present invention has been made in view of this point, and an object of the present invention is to reliably prevent frost from separating from an evaporator and falling to the air flow upstream side during a defrosting operation. .

[0007]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention is to prevent the frost of an evaporator from peeling off and falling to the upstream of the air flow immediately upstream of the air flow of the evaporator. And
At the time of the defrosting operation, the heat exchangers contributing to the melting of the frost are arranged to face each other.

[0008] Specifically, the invention according to claim 1 is a compressor.
(31), a condenser (32), an expansion mechanism (EV-2), and an evaporator (33) are provided with a refrigerant circuit (30) in which refrigerant is circulated in order by a refrigerant pipe so that refrigerant can be circulated. During the frost formation of the compressor (33), the refrigerant discharged from the compressor (31) is supplied to the evaporator (33) to form the frost.
It is assumed that a refrigeration system that performs a defrosting operation to melt (F). And, on the upstream side of the evaporator (33) in the air flow direction, the flow of the refrigerant is prevented during the freezing operation,
During the defrosting operation, the refrigerant discharged from the compressor (31) flows ,
The frost on the evaporator (33) peels off and falls to the upstream side of the air flow.
The defrost heat exchanger (52) prevents air from flowing through the evaporator (33).
Are opposed to each other a predetermined interval in the direction, the evaporator
Fin pitch of the radiation fins (58a) of the
Fin pitch of radiator fin (58b) of heat exchanger (52) is different
It is configured as follows .

With such a configuration, during refrigeration operation,
The refrigerant discharged from the compressor (31) is condensed in the condenser (32), decompressed by the expansion mechanism (EV-2), and evaporated in the evaporator (33). At this time, frost (F) may be generated on the upstream side of the evaporator (33) in the air flow direction. When the frost (F) is melted, the refrigerant discharged from the compressor (31) is supplied to the evaporator (33). When the frost (F) is thawed, the refrigerant discharged from the compressor (31) also flows into the defrost heat exchanger (52), which is disposed immediately upstream of the evaporator (33) in the air flow direction. . Thus, in the claimed invention,
The defrost heat exchanger (52) is located immediately upstream of the evaporator (33) in the air flow direction, and a predetermined distance from the evaporator (33) in the air flow direction.
By the opposed Te, the frost (F) is made to occur between the evaporator (33) and defrosting heat exchanger (52), the frost (F) is an evaporator (33 ), The evaporator (3
3) Falling further upstream in the air flow direction is prevented by the defrost heat exchanger (52). In addition, release of the evaporator (33)
Fin pitch of heat fins (58a) and release of defrost heat exchanger (52)
Since the fin pitch of the heat fin (58b) is different, the evaporator
The fin pitch of the radiation fin (58a) of (33) is
Heat dissipation of the defrost heat exchanger (52) while setting the size suitable for
Adjust the fin pitch of the fin (58b) during frost
Set dimensions to prevent bottoming down and frost melting well
It becomes possible. Therefore, the defrosting heat exchanger (52),
Contributes to melting of frost (F) and quickly forms frost (F)
Can be melted.

According to a second aspect of the present invention, there is provided a refrigerant circuit (30) in which a compressor (31), a condenser (32), an expansion mechanism, and an evaporator (33) are connected by a refrigerant pipe so that refrigerant can circulate. If frost forms on the evaporator (33) during the freezing operation, the refrigerant circulation direction is switched, and the refrigerant discharged from the compressor (31) is supplied to the evaporator (33) to reduce the frost (F). It is premised on a refrigerating device that performs a defrosting operation for melting. In the freezing operation, the condenser (3) is located immediately upstream of the evaporator (33) in the airflow direction.
While the refrigerant passing through 2) is supercooled, the compressor (3
The refrigerant discharged in 1) flows and melts the frost (F) together with the evaporator (33), and the frost on the evaporator (33) separates and the air flows upstream.
Defrosting heat exchanger to prevent the falling to the side (52), an evaporator
(33) and are disposed facing each other at a predetermined interval in the air flow direction.
The fin fins (58a) of the evaporator (33).
And the radiation fins (58b) of the defrost heat exchanger (52).
The switch is configured to be different .

With this configuration, during the refrigeration operation, the compressor
The refrigerant discharged from (31) is condensed in the condenser (32), and after being supercooled in the defrost heat exchanger (52), decompressed by the expansion mechanism,
It will evaporate in the evaporator (33). When melting the frost (F) generated on the upstream side in the air flow direction of the evaporator (33), the refrigerant circulation direction is switched, and the refrigerant discharged from the compressor (31) is cooled by the evaporator (33). And after being supplied to the defrost heat exchanger (52) to melt and condense the frost (F), the pressure is reduced by the expansion mechanism,
It will evaporate in the condenser (32). As described above, even in the case where the circulation direction of the refrigerant is switched between the refrigeration operation and the defrosting operation , the predetermined direction is set in the air circulation direction with the evaporator (33).
The defrosting heat exchanger (52), which is placed facing away from the
As a result, frost (F) can be prevented from falling from the evaporator (33) to the upstream side in the air flow direction , and the radiation fins of the evaporator (33) can be prevented.
(58a) Defrost heat exchanger having a different fin pitch than (52)
Thus, the frost (F) can be quickly melted.

According to a third aspect of the present invention, in the refrigeration apparatus according to the second aspect, the condenser (32), the defrost heat exchanger (52), and the evaporator (33) are connected by refrigerant pipes (30a, 30b). Connect in series. Also, the expansion mechanism includes a condenser (32) and a defrost heat exchanger.
(52) and a first inflation means (C) provided in the liquid pipe (30a).
P-5) and a second expansion means (EV-2) provided in a communication pipe (30b) between the evaporator (33) and the defrost heat exchanger (52). And, during the freezing operation, the condenser (32) and the defrost heat exchanger
The refrigerant condensed by flowing through (52) is decompressed by the second expansion means (EV-2) and then evaporated by the evaporator (33).
(33) and the refrigerant condensed in the defrost heat exchanger (52)
After the pressure was reduced by the expansion means (CP-5), the pressure was reduced by the condenser (32).

With this configuration, a circuit configuration for obtaining the operation according to the second aspect of the present invention can be specifically obtained .

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Example) Next, a first exemplary embodiment of the present invention with reference to the drawings. FIG. 1 shows a refrigerant circuit of a refrigeration apparatus (10) according to the present reference example . The refrigerating apparatus (10) of the present reference example is for cooling the inside of a refrigerator or a freezer, and as shown in FIG.
(31), a main refrigerant in which a condenser (32), an electric expansion valve (EV-2) and an evaporator (33) are connected in order by a refrigerant pipe (3a, 3b, 3c, 3d) so that refrigerant can be circulated. A circuit (30) is provided. That is, the compressor (31) and the condenser (32) are connected to the high-pressure gas pipe (3a), and the condenser (32) and the electric expansion valve (EV-2) are connected to the high-pressure liquid pipe (3c).
The electric expansion valve (EV-2) and the evaporator (33)
By (3d), the evaporator (33) and the compressor (31) are connected to a low-pressure gas pipe.
They are connected by (3b). Further, fans (32-F, 33-F) for flowing air are respectively disposed near the condenser (32) and the evaporator (33).

Then, the condenser (32) is out of the refrigerator, and the evaporator (33)
Are respectively installed in the refrigerator, the gas refrigerant discharged from the compressor (31) is condensed in the condenser (32), decompressed by the electric expansion valve (EV-2), and then evaporated in the evaporator (33). Thus, the inside air is cooled to thereby cool the inside of the refrigerator to a predetermined low temperature. The degree of opening of the electric expansion valve (EV-2) is adjusted so that the degree of superheat of the refrigerant at the outlet side of the evaporator (33) is kept constant.

A feature of this embodiment is that a bypass pipe (50) is provided between the high-pressure gas pipe (3a) and the low-pressure liquid pipe (3d) so that the gas refrigerant discharged from the compressor (31) can be bypassed. Is provided. The bypass pipe (50) is provided with a defrosting heat exchanger (52) disposed so as to be located immediately upstream of the evaporator (33) in the air flow direction. In addition, a three-way valve (54) is provided at a connection portion of the bypass pipe (50) to the high-pressure gas pipe (3a), and a state in which the discharge gas from the compressor (31) is supplied to the condenser (32). Bypass piping (5
The state to be supplied to the defrost heat exchanger (52) via (0) can be switched. Furthermore, a capillary tube (CP-) is provided upstream of the defrost heat exchanger (52) in the bypass pipe (50).
4) is provided.

Next, the arrangement of the evaporator (33) and the defrost heat exchanger (52) will be specifically described. As shown in FIG. 2, the evaporator (33) and the defrosting heat exchanger (52) are disposed near a suction port (56a) of a unit casing (56) constituting an in-compartment unit. In addition, a drain pan (40) for collecting drain falling from the evaporator (33) is provided below the unit casing (56). The fan (33-F) is provided near the outlet (56b) of the casing (56), and the suction port (56a) is driven by driving the fan (33-F).
Flows toward the outlet (56b) (see the arrow A in FIG. 2), and the air exchanges heat with the refrigerant when passing through the evaporator (33).

The evaporator (33) and the defrost heat exchanger (52)
Are both fin-and-tube type heat exchangers having common radiating fins (58). That is, a plurality of radiation fins (58) are arranged at predetermined intervals in a direction perpendicular to the plane of the paper of FIG. 2, and the refrigerant pipes (33a, 33a) of the evaporator (33) are
a,...) and the refrigerant pipes (52a, 52a,...) of the defrost heat exchanger (52) are arranged horizontally so as to pass through the radiation fins (58).

The arrangement of the refrigerant tubes (33a, 52a) will be described. The refrigerant tubes (33a, 33a,...) Of the evaporator (33)
The heat radiation fins (58) are disposed at the downstream end portion and the center portion in the air flow direction. For example, ends of pipes (33a, 33a,...) Opposed in the vertical direction in FIG. It is composed of two-pass pipes arranged in the air flow direction.

On the other hand, the refrigerant pipes (52a, 52a) of the defrost heat exchanger (52)
a, ...) are disposed at the upstream end of the radiating fins (58) in the direction of air flow, and the refrigerant pipes (33a, 3a) of the evaporator (33) are
3a,…)) and the pipes facing in the vertical direction (52a, 52
a, ...) are connected to each other by a U-shaped tube. That is, the refrigerant pipes (52a, 52a,...) Of the defrost heat exchanger (52)
Is composed of a one-pass pipe disposed upstream of the refrigerant pipes (33a, 33a, ...) of the evaporator (33) in the air flow direction.

The refrigerant pipes (33a, 52a) of the evaporator (33) and the defrosting heat exchanger (52) are located at positions facing each other in the direction of air flow, that is, at the same height. It is arranged. Thus, in the unit casing (56),
The air flowing from the inlet (56a) to the outlet (56b)
First, after flowing around the refrigerant pipes (52a, 52a,...) Of the defrost heat exchanger (52), the refrigerant flows around the refrigerant pipes (33a, 33a,...) Of the evaporator (33). I have.

Next, the operation of the refrigeration system (10) will be described. First, during the freezing operation for cooling the inside of the refrigerator, each fan (32-F, 33-F) is driven, and the three-way valve (54) connects the discharge side of the compressor (31) to the condenser (32). In the connected state, the refrigerant discharged from the compressor (31) flows only through the main refrigerant circuit (30) as shown by the solid arrow in FIG. That is,
This discharged refrigerant is condensed in the condenser (32), and the electric expansion valve (EV-
After decompressing in 2) and evaporating in the evaporator (33), heat exchange is performed with the air in the refrigerator to cool the air in the refrigerator.
A circulating state occurs such that the air is sucked into (31). Therefore, no refrigerant flows through the refrigerant pipe (52a) of the defrost heat exchanger (52).

When such a freezing operation is continuously performed for a predetermined time, moisture in the air inside the refrigerator passing through the evaporator (33) becomes free from frost (F) around the piping of the evaporator (33). This causes so-called frosting to occur. And this frost
As shown by the phantom line in FIG. 2 (a), the generation state of (F) is as follows:
That is, it is generated between the refrigerant pipes (33a, 33a, ...) of the evaporator (33) and the refrigerant pipes (52a, 52a, ...) of the defrost heat exchanger (52). For this reason, frost is hardly formed on the edge of the heat radiation fin (58).

In this state, when the frost (F) reaches a predetermined amount between the evaporator (33) and the defrost heat exchanger (52), the defrost operation is started.
(Defrost operation). In this defrosting operation,
When each fan (32-F, 33-F) is stopped,
(54) connects the discharge side of the compressor (31) and the defrost heat exchanger (52), that is, opens the bypass pipe (50), and the refrigerant discharged from the compressor (31) Is the bypass piping (5
0) is introduced into the defrost heat exchanger (52). The refrigerant (hot gas) introduced into the defrost heat exchanger (52) is subjected to the frost (F)
The refrigerant flows through the refrigerant pipes (52a, 52a,...) Of the defrost heat exchanger (52) while melting and melting the heat. The refrigerant derived from the defrost heat exchanger (52) is supplied to the low-pressure liquid pipe (3
It is introduced into the evaporator (33) via d). The refrigerant introduced into the evaporator (33) exchanges heat with the frost (F) and evaporates while melting the same as in the operation of the defrost heat exchanger (52) described above. After flowing through the refrigerant pipes (33a, 33a, ...) of the vessel (33),
It is sucked into the compressor (31) through the low-pressure gas pipe (3b) (Fig. 2
To the arrow indicated by the broken line).

Because of such an operation, the above frost formation
(F) is heated and melted from both the defrosting heat exchanger (52) and the evaporator (33), as shown in FIG. Become drain pan (40)
Will be collected and discharged. The defrosting operation may be performed when the refrigeration operation is continuously performed for a predetermined time (for example, 4 hours).

As described above, according to this embodiment ,
A defrost heat exchanger (52) is provided upstream of the air flow of the evaporator (33), and the refrigerant does not flow through the defrost heat exchanger (52) during the freezing operation. The formation of frost on the edges is avoided and, as before, the evaporator (33)
Frost is formed on the upstream edge in the air flow direction, which is separated during the defrosting operation, falls to the suction port side, and this frost cannot be collected in the drain pan. Can be avoided. In addition, during the defrosting operation, the discharged gas refrigerant flows through both the evaporator (33) and the defrosting heat exchanger (52). The frost operation time can be shortened.

(Second Embodiment ) Next, a second embodiment of the present invention will be described with reference to the drawings. Book
In the reference example , the arrangement structure of the evaporator and the defrost heat exchanger, which is a feature of the first reference example , is applied to a binary refrigeration apparatus including a high-temperature side refrigeration cycle and a low-temperature side refrigeration cycle. is there.

As shown in FIG. 3, the binary refrigeration system (10)
It cools a refrigerator or a freezer, and includes a high-temperature unit (1A) and a low-temperature unit (1B). Then, the high temperature side unit (1A) and the low temperature side unit
A high-temperature side refrigeration cycle (20) is constituted by a part of (1B), while a low-temperature side refrigeration cycle (30) is constituted by the low-temperature side unit (1B).

The high-temperature side refrigeration cycle (20) includes a compressor (2
1), and a condenser (22) connected to the discharge side of the compressor (21) via a high-pressure gas pipe (2a), and the condenser (22) includes a condenser fan (22-F ) Is provided. Further, the above condenser
One end of the main liquid pipe (2b) is connected to (22), and the compressor (2
One end of the main gas pipe (2c) is connected to the suction side of 1).

In the middle of the main liquid pipe (2b), an expansion valve (EV-1)
And the other end of the main liquid pipe (2b) is connected to the evaporator (23) of the cascade heat exchanger (1H). Also,
The other end of the main gas pipe (2c) is also connected to the evaporator (23) of the cascade heat exchanger (1H). The compressor (21) side of the main liquid pipe (2b) and the main gas pipe (2c) in the high temperature side refrigeration cycle (20) constitutes the high temperature side unit (1A). Specifically, the high-temperature side unit (1A) is
1), high pressure gas pipe (2a), condenser (22) and condenser fan (2
2-F) and a part of the main liquid pipe (2b) and the main gas pipe (2c).

The expansion valve (EV-1) is, as shown in FIG.
It consists of an external pressure equalizing type temperature-sensitive expansion valve, and the temperature-sensitive cylinder (T1) is attached to the refrigerant outlet side of the evaporator (23) in the cascade heat exchanger (1H), that is, to the main gas pipe (2c). . Further, an external pressure equalizing pipe (E1) is connected to the high temperature side expansion valve (EV-1), and the external pressure equalizing pipe (E1) includes a three-way switching valve (SV-1) and a main gas pipe (2c). Is connected to the mounting part of the temperature sensing tube (T1).

One port of the three-way switching valve (SV-1) is connected to the main gas pipe (2c), and when the three-way switching valve (SV-1) is turned on, the liquid refrigerant pressure is increased by the expansion valve (EV-1). ) To act on the expansion valve (E
V-1) is closed while the gas refrigerant pressure acts on the expansion valve (EV-1) when the three-way switching valve (SV-1) is turned off so that the gas refrigerant has a predetermined degree of superheat. EV-1) opens at a predetermined opening.

On the other hand, as shown in FIG. 4, the low-temperature side refrigeration cycle (30) includes a compressor (31) and a cascade heat exchanger (1H).
Of the condenser (32), the expansion valve (EV-2) which is the expansion mechanism, and the evaporator (3
3) are connected in order, and the evaporator (33) is provided with an evaporator fan (33-F). The main liquid pipe (2b) and the main gas pipe in the high temperature side refrigeration cycle (20)
The low temperature side unit (1B) is constituted by the cascade heat exchanger (1H) side and the low temperature side refrigeration cycle (30) in the middle of (2c). Specifically, the low-temperature side unit (1B) includes a low-temperature side refrigeration cycle (30) and an evaporator (23) of a cascade heat exchanger (1H).
And a part of the main liquid pipe (2b) and the main gas pipe (2c), the high temperature side expansion valve (EV-1) and the temperature sensing cylinder (T1).

The low temperature side expansion valve (EV-2) is constituted by an external pressure equalizing type temperature sensitive expansion valve, and the temperature sensitive cylinder (T2) is connected to the low temperature side evaporator (3).
The refrigerant outlet side of 3), that is, the low pressure gas pipe (3b) is attached, and the external pressure equalizing pipe (E2) is connected. The external pressure equalizing pipe (E2) is a temperature-sensitive cylinder (T2) in the low-pressure gas pipe (3b).
And the low-temperature side expansion valve (EV-2) is opened to a predetermined opening so that the gas refrigerant has a predetermined degree of superheat.

The high-pressure gas pipe (3a) on the discharge side of the low-temperature compressor (31) is provided with a four-way switching valve (34).
In (34), the first port on the pressurization side and the third port on the outflow / inflow side are connected to the high-pressure gas pipe (3a), while the differential pressure passage for operation (35) is connected to the second port on the return side. A hot gas bypass passage (36) is connected to the fourth port on the outflow / inflow side.

The differential pressure passage (35) is connected to the low-pressure gas pipe (3b) on the suction side of the compressor (31), and is connected to the four-way switching valve (3).
A check valve (CV-1) and a capillary tube (CP-1) that allow only refrigerant flow from 4) to the suction side of the compressor (31) are provided.

The hot gas bypass passage (36) is connected to the suction side of the low temperature side evaporator (33), that is, the expansion valve (EV-2) and the evaporator.
(33), a hot gas is supplied to the low-temperature side evaporator (33) every predetermined time, for example, every four hours, to form frost on the evaporator (33). Configured to remove. Furthermore, in the middle of the hot gas bypass passage (36), drain pan heater (H1) and drain pan heaters (H2) and fan guard heater (H3) and the reference example defrosting heat exchanger, characterized in (52) Are connected in parallel with each other and the compressor
A check valve (CV-2) is provided to allow only the refrigerant flow from the discharge side of (31) to the low-temperature side evaporator (33).

The drain pan heater (H1) is connected to the low-temperature side evaporator (3
Drain pan provided below 3) is to remove frost, and the drain receiving heater (H2) is disposed at the lower end of the evaporator (33) and receives frost from a drain receiving member (not shown) that receives falling frost. The fan guard heater (H3)
It removes frost around the evaporator fan (33-F). The defrost heat exchanger (52) is disposed opposite to the evaporator (33) immediately upstream of the air flow, similarly to the first reference example (see FIG. 2).

The low-temperature side refrigeration cycle (30) includes:
A capacity control bypass passage (37) is provided. One end of the capacity control bypass passage (37) is connected to a high-pressure gas pipe (3a) between the compressor (31) and the four-way switching valve (34), and the other end is an expansion valve (EV-2). It is connected to a liquid pipe (3c) between the evaporator (33). The capacity control bypass passage (37)
A solenoid valve (SV-3) and a capillary tube (CP-3) are provided, and the hot gas discharged from the compressor (31) is evaporated by the evaporator (33).
To adjust the cooling capacity.

The high pressure gas pipe (3a) of the low temperature side refrigeration cycle (30) has a high pressure switch (HPS1) that outputs an abnormal signal when the high pressure refrigerant pressure rises abnormally, and a high pressure refrigerant pressure of a predetermined high pressure value. High pressure sensor (H
PS2), and in the hot gas bypass passage (36),
A defrost pressure sensor (HPS3) that outputs a defrost termination signal when the high-pressure refrigerant pressure, which is the hot gas pressure, reaches a predetermined high pressure value is provided.

The low-pressure gas pipe (3b) of the low-temperature side refrigeration cycle (30) has a low-pressure pressure switch (LPS1) that outputs an abnormal signal when the low-pressure refrigerant pressure abnormally decreases, and a low-temperature side evaporator.
(33) A defrost temperature sensor that outputs a defrost end signal when the refrigerant temperature on the refrigerant outflow side reaches a predetermined high temperature.
(Th-1).

Next, the operation of the binary refrigeration system (10) will be described.

In this operation, both the high temperature side compressor (21) and the low temperature side compressor (31) are driven, and the high temperature side condenser fan (22-F) and the low temperature side evaporator fan (33-F) are also operated. Drive together. Then, the three-way switching valve (SV-1) is turned off, and the external pressure equalizing pipe (E1) of the high temperature side expansion valve (EV-1) communicates.

In this state, in the high-temperature side refrigeration cycle (20), the refrigerant discharged from the compressor (21)
It condenses in 2) to become a liquid refrigerant and flows to the low-temperature unit (1B). Then, after the pressure of the liquid refrigerant is reduced by the expansion valve (EV-1), the liquid refrigerant evaporates in the evaporator (23) of the cascade heat exchanger (1H) and returns to the compressor (21) as a gas refrigerant. And this cycle is repeated.

On the other hand, in the low-temperature side refrigeration cycle (30), the refrigerant discharged from the compressor (31) is condensed in the condenser (32) of the cascade heat exchanger (1H) to become a liquid refrigerant. After the pressure is reduced by the expansion valve (EV-2), the refrigerant evaporates in the evaporator (33) and returns to the compressor (31) as a gas refrigerant, and this circulation is repeated. Then, the low-temperature side evaporator (33) generates cooling air to cool the inside of the refrigerator.

The defrosting operation is performed at predetermined time intervals such as four hours.
(Defrost operation), in which case the operation of the high-temperature side refrigeration cycle (20) is stopped, so the high-temperature side compressor (21) and the high-temperature side condenser fan (22-F) are stopped, and the three-way switching is performed. The valve (SV-1) is turned on and the high temperature side expansion valve (EV-1) is fully closed. Then, in the low temperature side refrigeration cycle (30), the four-way switching valve (34) is switched to the broken line in FIG. 4 to drive the compressor (31). In this state, the hot gas (high-temperature gas refrigerant) discharged from the low-temperature side compressor (31) flows through the hot gas bypass passage (36) from the four-way switching valve (34), and the heaters (H1, H2, H3 )
After passing through the refrigerant pipes (52a, 52a,...) Of the defrost heat exchanger (52), it is supplied to the low-temperature side evaporator (33) and returns to the compressor (31). Will be.

As described above, also in the present embodiment , the refrigerant is prevented from flowing through the defrost heat exchanger (52) during the freezing operation, so that the frost is formed on the upstream edge of the evaporator (33) in the air flow direction. Is generated, and this is separated during the defrosting operation and falls to the suction port side, so that it is possible to avoid occurrence of a situation in which this frost cannot be collected in the drain pan. In addition, at the time of the defrosting operation, the frosting (F) can be quickly melted from both the front and back sides, and the defrosting operation time can be shortened.

In this embodiment , the case where the present invention is applied to a binary refrigeration system in which one high-temperature unit is connected to one low-temperature unit is described. It is also possible to apply the present invention to a multi-type binary refrigeration system in which a plurality of low-temperature units are connected.

Next (Third Reference Example), a description will be given of a third exemplary embodiment of the present invention. FIG.
3 shows a refrigerant circuit of a refrigeration apparatus (10) according to the present reference example .
The refrigerating device (10) of the present reference example includes a compressor (31), a condenser (32),
A main refrigerant circuit (30) is provided in which the defrost heat exchanger (52) and the evaporator (33) are sequentially connected by a refrigerant pipe so that the refrigerant can circulate. The discharge side and the suction side of the compressor (31) are connected to a four-way switching valve (34), and the operation of the four-way switching valve (34) causes the discharge side of the compressor (31) to be connected to the condenser. (32) and the suction side is connected to the evaporator (33) (switching state shown by a solid line in FIG. 5), and the discharge side of the compressor (31) is connected to the evaporator (33).
And the suction side connected to the condenser (32) (FIG. 5).
(A switching state indicated by a broken line).

A part of the liquid pipe (30a) connecting the condenser (32) and the defrost heat exchanger (52) is branched into two systems, one of which is connected to the condenser (32). A check valve (CV-3) that allows only the flow of the refrigerant to the frost heat exchanger (52) is provided, and a capillary tube (CP-5) as the first expansion means is provided on the other side. A part of a communication pipe (30b) connecting the evaporator (33) and the defrost heat exchanger (52) is also branched into two systems, one of which is a defrost heat exchanger from the evaporator (33). A check valve (CV-4) that allows only the flow of the refrigerant to the vessel (52), and an electric expansion valve (EV-2) as a second expansion means whose opening degree is freely adjustable is provided on the other side. I have. Thus, the capillary tube (C
P-5) and the electric expansion valve (EV-2) constitute an expansion mechanism. Further, fans (32-F, 33-F) for flowing air are respectively disposed near the condenser (32) and the evaporator (33).

Also in this embodiment , as shown in FIG. 2, the defrost heat exchanger (52) is disposed immediately upstream of the evaporator (33) in the air flow direction. (33) side fan (33-
With the driving of (F), air flows into the refrigerant pipe (5) of the defrost heat exchanger (52).
2a, 52a,...), And then flow through the refrigerant pipe (3) of the evaporator (33).
3a, 33a,…).

Next, the operation of the refrigeration system (10) will be described. First, during the freezing operation for cooling the inside of the refrigerator, the fans (32-F, 33-F) are driven together, and the four-way switching valve (3
4) is in the switching state on the solid line side, and the electric expansion valve (EV-2) is set to a predetermined opening (an opening that keeps the degree of superheating of the refrigerant constant).
When the compressor (31) is driven in this state, the refrigerant discharged from the compressor (31) is condensed in the condenser (32) as shown by the solid arrow in FIG. After passing through -3), it is supercooled by the defrosting heat exchanger (52), then depressurized by the electric expansion valve (EV-2), and evaporated by the evaporator (33) to be separated from the air in the refrigerator. After the internal air is cooled by performing heat exchange between them, a circulation state is established in which the air is sucked into the compressor (31). That is, the defrost heat exchanger (52) functions as a condenser. At this time, the air is once heated when passing through the defrost heat exchanger (52), and then cooled by exchanging heat with the refrigerant in the evaporator (33). For this reason, the degree of superheat of the refrigerant at the outlet side of the evaporator (33) can be increased to a predetermined value, and the capacity of the evaporator (33) can be maximized.

The upstream end of the evaporator (33) on the air flow side
When switching to the defrosting operation due to frost formation (between the evaporator (33) and the defrost heat exchanger (52)), the fan (3
Only 2-F) is driven, the four-way switching valve (34) is switched to the broken line side, and the electric expansion valve (EV-2) is set to the fully closed state. When the compressor (31) is driven in this state, the refrigerant discharged from the compressor (31) is supplied to the evaporator (33) and the defrosting heat exchanger (52) as indicated by a dashed arrow in FIG. And condenses while melting the frost (F) between the two, then decompressed in the capillary tube (CP-5) and evaporated in the condenser (32),
A circulation state is established such that the air is sucked into the compressor (31). That is, also in this case, the defrost heat exchanger (52) functions as a condenser. The operation of ending the defrosting operation at this time is performed based on the refrigerant temperature at the outlet side of the evaporator (33) or the defrosting heat exchanger (52) and the discharge pressure of the compressor (31).

[0054] Thus, also in this reference example, frost is prevented from occurring at the edge portion of the heat radiating fins (58), frost during defrosting operation ends up falling into the suction port side, the frost Can be prevented from being collected in the drain pan, and the frost (F) can be quickly melted.

( Embodiment ) Next, an embodiment of the present invention will be described. This form is
It is a modification of the evaporator and the defrost heat exchanger,
It can be applied to the same refrigerant circuit as the reference example . For this reason,
In the present embodiment, only the configurations of the evaporator and the defrost heat exchanger will be described.

As shown in FIG. 6, the evaporator (33) and the defrosting heat exchanger (52) each have a structure in which refrigerant pipes (33a, 52a) penetrate through independent radiation fins (58a, 58b). Has become. That is, the evaporator (33) and the defrost heat exchanger (52) are independent fin-and-tube heat exchangers, and are adjacent to each other in the air flow direction. And evaporator (33)
Fins (58a) of the defrost heat exchanger (52)
8b) are arranged at predetermined intervals in the air flow direction.

According to such a configuration, the fin pitch of the radiating fins (58a) of the evaporator (33) (the distance between the fins in the vertical direction in FIG. 6) and the radiating fins of the defrosting heat exchanger (52).
(58b) The fin pitch can be set differently. Therefore, while setting the fin pitch of the radiation fins (58a) of the evaporator (33) to a size suitable for cooling air, the fin pitch of the radiation fins (58b) of the defrost heat exchanger (52) is
In the defrosting operation, it is possible to prevent the frost from dropping and to set the size to allow the frost to be well melted.

In each of the above-described reference examples and embodiments ,
Although the case where the present invention is applied to a refrigerator or a freezer that cools the inside of the refrigerator has been described, the present invention is not limited to this, and the present invention is not limited to this. It may be used to melt frost.

[0059]

As described above, according to the present invention, the following effects can be obtained. According to the first aspect of the present invention, the refrigerant flow is blocked immediately upstream of the evaporator in the air flow direction during the freezing operation, the refrigerant discharged from the compressor flows during the defrosting operation , and the frost of the evaporator is separated.
A defrosting heat exchanger that prevents falling to the upstream side of the air circulation is disposed facing the evaporator at a predetermined interval in the air circulation direction, and furthermore, the fin pitch of the radiation fins of the evaporator,
The fin pitch of the radiation fin of the defrost heat exchanger is different.
With this configuration, even if the frost generated in the evaporator is separated from the evaporator, it is prevented by the defrost heat exchanger from falling from the evaporator to the upstream side in the air flow direction, The frost formation is favorably collected, and the reliability of the evaporator can be improved. Also, the heat radiation of the evaporator
The fin pitch of the fin and the fin of the radiation fin of the defrost heat exchanger
The pitch of the radiation fins of the evaporator
While setting the pitch to a size suitable for cooling air,
Defrosting operation of the fin pitch of the radiating fins of the defrost heat exchanger
Dimensions that prevent frost formation and prevent frost melting
Method can be set, evaporator and defrost heat exchange
The configuration of the vessel can be adapted to each purpose,
The refrigeration capacity and defrosting capacity of the refrigeration system can be improved.
You.

According to the second aspect of the present invention, the refrigerant that has passed through the condenser is supercooled during the freezing operation and the refrigerant discharged from the compressor during the defrosting operation is located immediately upstream of the evaporator in the air flow direction. Melts frost together with the evaporator and evaporates
To prevent the frost of the vessel from peeling and falling to the upstream side of the air circulation.
The defrost heat exchangers are placed opposite each other ,
The fin pitch of the fin and the radiation fin of the defrost heat exchanger
Even if the circulating direction of the refrigerant is switched between the refrigeration operation and the defrosting operation by configuring the fin pitch to be different from the fin pitch , the frost drops from the evaporator to the upstream in the air circulation direction. Can be stopped and the evaporator
For defrost heat exchangers with different fin pitches from heat fins
Therefore, it is possible to shorten the defrosting operation time by speeding up the melting of the frost.

According to the third aspect of the invention, the liquid pipe between the condenser and the defrost heat exchanger is provided with the first expansion means for reducing the pressure of the circulating refrigerant during the defrost operation, and By providing the communication pipe between the defrosting heat exchanger and the second expansion means for decompressing the circulating refrigerant during the refrigeration operation, the effect according to the second aspect of the present invention is exerted. The circuit configuration is specifically obtained, and the practicability of the refrigeration apparatus can be improved .

[Brief description of the drawings]

FIG. 1 is a diagram showing a refrigerant circuit of a refrigeration apparatus according to a first reference example .

FIG. 2 is a sectional view of an in-compartment unit.

FIG. 3 is a refrigerant circuit diagram illustrating a binary refrigeration apparatus according to a second reference example .

FIG. 4 is a refrigerant circuit diagram showing a low-temperature side unit in a second reference example .

FIG. 5 is a diagram corresponding to FIG. 1 in a third reference example .

FIG. 6 is a diagram corresponding to FIG. 2 in the embodiment .

FIG. 7 is a diagram corresponding to FIG. 2 in a conventional example.

[Explanation of symbols]

 (30) Low temperature refrigeration cycle (refrigerant circuit) (31) Compressor (32) Condenser (33) Evaporator (52) Defrost heat exchanger (33a, 52a) Refrigerant tube (58, 58a, 58b) Radiation fin (F) Frost (EV-2) Expansion valve (expansion mechanism, second expansion means) (CP-5) Capillary tube (first expansion means)

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-177765 (JP, A) JP-A-6-123499 (JP, A) JP-A-6-46269 (JP, U) JP-A-62-269 171765 (JP, U) Japanese Utility Model Showa 55-178672 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) F25B 47/02 530

Claims (3)

(57) [Claims] 1. A compressor (31), a condenser (32), an expansion mechanism (EV-
2) and a refrigerant circuit (30) in which the evaporator (33) is connected in order so that the refrigerant can circulate through the refrigerant pipe, and when the evaporator (33) is frosted by the freezing operation, the compressor (31) Evaporator for discharged refrigerant
In the refrigerating apparatus, which is supplied to the evaporator (33) to perform the defrosting operation of melting the frost (F), the refrigerant flow is stopped immediately upstream of the evaporator (33) in the air flow direction during the freezing operation. The compressor (3
As the refrigerant discharged in 1) flows , the frost on the evaporator (33) peels off
A defrost heat exchanger (52) that prevents the evaporator (33) from dropping to the air
Arranged to face Te, and the fin pitch of the heat radiating fins (58a) of the evaporator (33),
The fin pitch of the radiation fins (58b) of the defrost heat exchanger (52)
Is configured to be different from each other . 2. A refrigerant circuit (30) in which a compressor (31), a condenser (32), an expansion mechanism and an evaporator (33) are connected so that refrigerant can circulate through refrigerant pipes, , Evaporator (3
When frost occurs in 3), the refrigerant circulation direction is switched, and the refrigerant discharged from the compressor (31) is supplied to the evaporator (33) to perform a defrosting operation of melting the frost (F). In the refrigeration apparatus, on the upstream side of the evaporator (33) in the air flow direction, the refrigerant passing through the condenser (32) is supercooled during the freezing operation, while the discharge of the compressor (31) is performed during the defrosting operation. The refrigerant flows to melt the frost (F) together with the evaporator (33), and the frost on the evaporator (33) is removed.
A defrost heat exchanger (52) that prevents the evaporator (33) from separating and falling to the upstream side of the airflow
And they are arranged to face each other, and the fin pitch of the heat radiating fins (58a) of the evaporator (33),
The fin pitch of the radiation fins (58b) of the defrost heat exchanger (52)
Is configured to be different from each other . The condenser (32), the defrosting heat exchanger (52) and the evaporator (33) are connected in series by refrigerant pipes (30a, 30b), and the expansion mechanism comprises a condenser (32). ) And the first expansion means (CP-5) provided in the liquid pipe (30a) between the defrost heat exchanger (52).
And a communication pipe (3) between the evaporator (33) and the defrost heat exchanger (52).
0b), the refrigerant condensed by flowing through the condenser (32) and the defrost heat exchanger (52) during the refrigeration operation is supplied to the second expansion means (EV-2). After decompression by -2),
During the defrosting operation, the refrigerant condensed in the evaporator (33) and the defrost heat exchanger (52) is evaporated by the evaporator (33), and the refrigerant expanded in the first expansion means (CP-
3. The refrigeration system according to claim 2, wherein the pressure is reduced by the method (5), and then the vaporization is performed in the condenser (32) .