JP2570536B2 - 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 refrigeration system having an external pressure equalizing type temperature automatic expansion valve, and more particularly to a refrigeration system in which the connection of the external pressure equalizing pipe of the automatic expansion valve is switched between a suction line and a high pressure line. Regarding improvement.

[0002]

2. Description of the Related Art Conventionally, for example, Japanese Patent Publication No. 47-2431
As disclosed in Japanese Unexamined Patent Publication No. 1 (1993), a refrigerant circuit is provided by sequentially connecting a compressor, a condenser, an external pressure equalizing type temperature automatic expansion valve, and an evaporator. The compressor can be switched between the suction pressure of the medium circuit and the high-pressure side pressure. During the operation of the compressor, the suction pressure is introduced to perform the superheat constant control, while when the compressor is stopped, the high-pressure side pressure is introduced. It is a known technique to secure the closing operation of the automatic expansion valve and to prevent the liquid refrigerant from flowing into the evaporator side from the high pressure line while the compressor is stopped, thereby causing problems such as liquid compression.

[0003]

In a refrigerating apparatus having an automatic temperature expansion valve, the opening of the automatic expansion valve is automatically adjusted so as to keep the degree of superheat constant. Also, when the compressor is stopped, it is opened with a certain degree of opening. Therefore, if the compressor is stopped, the liquid refrigerant flows from the high-pressure side (for example, the receiver) to the low-pressure side evaporator while the compressor is stopped, and a problem such as liquid compression occurs when the compressor is restarted. Generally, an electromagnetic on-off valve is interposed between the receiver and the automatic expansion valve, and when the compressor is stopped, the on-off valve is closed to shut off the flow of the liquid refrigerant. To avoid the decompression effect on the valve, it was necessary to increase the capacity of the solenoid on-off valve.

In the above publication, the automatic expansion valve is of an external pressure equalizing type, and a high pressure is introduced into the external pressure equalizing pipe of the automatic expansion valve while the compressor is stopped, so that the automatic expansion valve has a fully closed function. To solve the above problem.

[0005] However, in the above publication,
As the compressor is repeatedly turned on and off, the opening operation of the automatic expansion valve at the time of starting the compressor is gradually delayed, and the state in which the automatic expansion valve is throttled is maintained.
There is a problem that a so-called low-pressure cut occurs.

The present invention, liquid refrigerant is generated by refrigerant condensed in an external pressure equalizing pipe, a low pressure transmission to the automatic expansion valve is inhibited to the liquid refrigerant remaining in the external equalizing pipe The present invention has been made by focusing on the fact that the above-mentioned low pressure cut is caused by such a fact. The purpose of the purpose is to provide a means for removing the liquid refrigerant in the external pressure equalizing pipe, thereby making the compressor smooth. Is to ensure a proper startup.

[0007]

In order to achieve the above object, a solution of the present invention is to provide an external pressure equalizing pipe of an automatic expansion valve with a downward gradient from the automatic expansion valve side to the suction line side.

Specifically, as shown in FIG. 1, means taken by the invention of claim 1 includes a compressor (1), a condenser (2),
The present invention is directed to a refrigerating apparatus having a main refrigerant circuit (8) in which an external pressure equalizing temperature automatic expansion valve (5) and an evaporator (6) are sequentially connected.

The external pressure equalizing pipe (10) of the automatic expansion valve (5) connected to the suction line (7a) of the main refrigerant circuit (8), one part of the external pressure equalizing pipe (10) and a high pressure line A high-pressure inlet pipe (11) for connecting to the upper part and the external pressure equalizing pipe (1) in conjunction with the start / stop of the compressor (1).
A switching mechanism (12) for switching the automatic expansion valve side passage of (0) to communicate with the suction line (7a) side and the high pressure introduction pipe (11) side is provided.

Here, the automatic expansion valve (5) and the switching device
Structure (12) and the external pressure equalizing tube (10)-suction line
The connection part of (7a) is arranged so that the height position is gradually lowered.
It has been location, the automatic expansion valve (5), the switching mechanism (1
2) and the external pressure equalizing pipe connecting the suction line (7a)
(10) is a suction line (7) from the automatic expansion valve (5) side.
a) It is configured to be inclined downward toward the side.
It is.

According to a second aspect of the present invention, in the first aspect of the present invention, a plurality of sets of the evaporator (6) and the automatic expansion valve (5) are provided. After the equalizing pipes (10a to 10c) are joined, the common main pipe (1
0) through the suction line (7a) and the high pressure introduction pipe (1)
Connect to 1).

The switching mechanism (12) is provided below the lowermost automatic expansion valve (5c).

A third aspect of the present invention is the means for automatically expanding the main refrigerant circuit (8) and the portion forming the automatic expansion valve side passage of the external pressure equalizing pipe (10). The valve (5) is provided with an auxiliary heat exchanger (4) that straddles the liquid pipe on the upstream side and exchanges heat between the refrigerants in both pipes.

[0014]

With the above arrangement, according to the first aspect of the present invention, the suction line (7a) is connected to the external pressure equalizing pipe (10) of the automatic expansion valve (5) during operation of the refrigeration system and during operation of the compressor (1). Automatic expansion valve (5) so as to keep the suction superheat constant while compensating for the pressure drop in the evaporator (6).
Is automatically adjusted. The switching mechanism (12) interlocks with the stoppage of the compressor (1) and controls the external pressure equalizing pipe (1).
The connection with the passage on the side of the automatic expansion valve of 0) is a high pressure introduction pipe (11).
Side, the high pressure is introduced as the control pressure of the automatic expansion valve (5), and while the compressor (1) is stopped, the automatic expansion valve (5) is kept fully closed, and the evaporator (6) side The liquid refrigerant is prevented from flowing into the air.

At this time, via the high pressure introduction pipe (11),
Even if the high-pressure gas refrigerant is introduced into the external pressure equalizing pipe (10), when the ambient temperature is low, the high-pressure gas refrigerant condenses and liquefies as the compressor (1) is repeatedly turned on and off, so that the external pressure equalizing pipe
When gradually accumulating in (10), when starting the compressor (1),
Transmission of the low pressure to the automatic expansion valve (5) is hindered, and the opening operation of the automatic expansion valve (5) is delayed, so that the refrigeration apparatus may be abnormally stopped due to the low pressure cut.

In the present invention, the external pressure equalizing pipe (10)
Moves from the automatic expansion valve (5) side to the suction line (7a) side.
Since the inclined selfish downward, even if the external pressure equalizing pipe (10) in the liquid refrigerant gas refrigerant is condensed in <br/>, liquid refrigerant Ru is promptly discharged to the suction line (7a). Therefore,
The transmission of the low pressure to the dynamic expansion valve (5) is not delayed, and the low pressure cut at the time of starting the compressor (1) as described above is effectively prevented.

According to the second aspect of the present invention, the same operation as the first aspect is performed.
For a plurality of evaporators (6a to 6c) and automatic expansion valves (5a to 5c), start and stop of the compressor (1) by a common switching mechanism (12) via a common main pipe (10). in conjunction with, the low pressure or high pressure in an external pressure equalizing pipe (10a to 10c) of the automatic expansion valve (bodies 5a to 5c) is introduced, the evaporators of the liquid refrigerant in the stopping and the degree of superheat constant control action during operation ( 6a to 6c), the three-way switching valve (12) is mounted below the lowermost automatic expansion valve (5c).
The function of discharging the liquid refrigerant in the external pressure equalizing pipe (10) is obtained. Therefore, it is not necessary to arrange a high-pressure introduction pipe and a switching mechanism for each of the automatic expansion valves (6a to 6c), and the cost is greatly reduced.

According to the third aspect of the present invention, the operation of the first or second aspect is provided.
In addition, in the auxiliary heat exchanger (4), the refrigerant in the external pressure equalizing pipe (10) is heated by heat exchange with the high-temperature refrigerant flowing through the liquid pipe of the main refrigerant circuit (8). The generation of the liquid refrigerant due to the condensation of the gas refrigerant in the pressure equalizing pipe (10) is suppressed.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG.

FIG. 1 shows a refrigerant piping system of a refrigerating apparatus according to an embodiment, wherein (1) is a compressor, and (2) is the compressor (1).
And (3) a receiver for storing the liquid refrigerant condensed in the condenser (2). (6a to 6c) are evaporators arranged in parallel with each other, and (5a to 5c) are evaporators (6a to 6c).
6c) is an external pressure equalizing type temperature automatic expansion valve functioning as a pressure reducing mechanism. The above devices are connected by a refrigerant pipe (7) to form a closed circuit main refrigerant circuit (8).

Here, as a feature of the present invention, each of the external pressure equalizing pipes ( 10a to 10c) of each of the automatic expansion valves (5a to 5c) is characterized.
c) is connected to the suction line (7a) after merging with the common external pressure equalizing main pipe (10) . Although not shown, the temperature-sensitive cylinder of each of the automatic expansion valves (5a to 5c) is connected to the suction line (7).
The automatic expansion valves (5a to 5c) are adjusted in accordance with the degree of suction superheat. One part of the external pressure equalizing main pipe (10) and the gas storage part above the receiver (3) are connected to the high pressure introducing pipe (1).
The external pressure equalizing main pipe (10) is connected to the connection between the high-pressure inlet pipe (11) and the external pressure equalizing main pipe (10) in conjunction with the start / stop of the compressor (1). Three-way switching valve (12) as a switching mechanism for alternately switching the introduction path of the control pressure to the external pressure equalizing pipes (10a to 10c) through the suction line (7a) and the receiver (3) (high-pressure line)
Is interposed. That is, during the operation of the compressor (1), the three-way switching valve (12) is switched to the suction line (7a) side so that the degree of opening of each of the automatic expansion valves (5a to 5c) is constant at the suction superheat. Compressor (1)
When the operation is stopped, the three-way switching valve (12) is switched to the high pressure line side, high pressure is introduced as the control pressure of each automatic expansion valve (5a-5c), and each automatic expansion valve (5a-5c) is kept fully closed. It has been made to be.

Also, between the three-way switching valve (12) and the external pressure equalizing pipes (10a to 10c) of the external pressure equalizing main pipe (10).
Over a predetermined distance (that is, constitute the automatic expansion valve side passage)
And the common liquid pipe between the receiver (3) and the automatic expansion valves (5a to 5c) of the main refrigerant circuit (8) is provided so as to be in contact with each other, and heat exchange between the refrigerants in both pipes is performed. The auxiliary heat exchanger (4) according to the third aspect of the present invention is constituted by the two pipes .
That is, the gas refrigerant in the external pressure equalizing main pipe (10) is heated by heat exchange with the high-temperature liquid refrigerant in the main refrigerant circuit (8),
Liquefaction due to the condensation is suppressed.

Further, the three-way switching valve (12) is a lowermost one of the automatic expansion valves (5a to 5c).
c), and the whole of the external pressure equalizing pipes (10a to 10c) and the external pressure equalizing main pipe (10) are moved from the automatic expansion valves (6a to 6c) toward the suction line (7a). Is configured to incline downwards and
The liquid refrigerant generated in the pressure equalizing tubes (10a) to (10c ) is quickly discharged to the suction line (7a).

Therefore, in the above embodiment, during operation of the refrigeration system, during operation of the compressor (1), each automatic expansion valve (5a
To 5c), the low pressure of the suction line (7a) is introduced into each external pressure equalizing pipe (10a to 10c), and the evaporator (6a to 6c)
The opening degree of each of the automatic expansion valves (5a to 5c) is automatically adjusted so as to keep the degree of suction superheat constant while compensating for the pressure drop in. Then, in conjunction with the stop of the compressor (1), the connection of the external pressure equalizing main pipe (10) to the automatic expansion valve side passage is switched to the high pressure introduction pipe (11) side.
A high pressure is introduced as a control pressure of a to 5c), and while the compressor (1) is stopped, the automatic expansion valves (5a to 5c) are kept fully closed, and each of the automatic expansion valves (5a to 5c) is moved toward the evaporator (6a to 6c). Is prevented from flowing.

At this time, since the high-pressure inlet pipe (11) is connected to the gas reservoir of the receiver (3), high-pressure gas refrigerant is introduced into the external pressure equalizing main pipe (10). In such a case, the high-pressure gas refrigerant may be condensed and liquefied and gradually accumulate in the pipe while the compressor (1) is repeatedly turned on and off. Even when the three-way switching valve (12) is switched to the suction line (7a) when the compressor (1) is started, transmission of low pressure is hindered by the liquid refrigerant, and the automatic expansion valves (5a to 5c) If the opening of the main refrigerant circuit (8) is delayed, the low pressure of the main refrigerant circuit (8) instantaneously drops excessively, and the refrigeration apparatus may abnormally stop due to so-called low pressure cut.

Here, in the above embodiment, each of the external pressure equalizing pipes (10a to 10c) and the external pressure equalizing main pipe (10) is
From the side of each of the automatic expansion valves (5a to 5c) to the suction line (7).
Since it is formed so as to be inclined downward toward the side a), even if the gas refrigerant is condensed into a liquid refrigerant in the pipe, the liquid refrigerant is quickly discharged to the suction line (7a), and as described above. Low pressure cut at the time of starting the compressor (1) is effectively prevented.

An auxiliary heat exchanger (4) is provided so as to extend over a portion of the external pressure equalizing main pipe (10) constituting the passage on the side of the automatic expansion valve and the liquid pipe of the main refrigerant circuit (8). Pressure main pipe (1
In the case where the gas refrigerant in 0) and the high-temperature liquid refrigerant flowing through the liquid pipe are configured to be able to exchange heat, the condensation of the gas refrigerant in the external pressure equalizing main pipe (10) is suppressed, and the storage effect of the liquid refrigerant is prevented. Becomes noticeable.

Further, the configuration of the present invention is not limited to the configuration in which a plurality of evaporators (6a to 6c) are provided as in the above-described embodiment, but in particular, as in the above-described embodiment, a plurality of evaporators (6a to 6c) are provided. 6a to 6c) and the automatic expansion valves (5a to 5c), the external pressure equalizing pipes (10a to 10c) of the automatic expansion valves (5a to 5c) are merged into a common main pipe (10).
By connecting the high pressure introduction pipe (11) to the external pressure equalizing main pipe (10) and attaching the three-way switching valve (12) below the lowermost automatic expansion valve (5c),
There is no need to arrange a high-pressure inlet pipe and a switching valve for each of the automatic expansion valves (6a to 6c), and a significant cost reduction can be achieved while maintaining the above-described liquid refrigerant discharge effect.

In the above-described embodiment, the three-way switching valve (12) is provided as the switching mechanism. However, the present invention is not limited to this embodiment. 10) It may be provided in the passage on the suction line (7a) side and the high pressure introduction pipe (11).

[0030]

As described above, according to the first aspect of the present invention, an external pressure equalizing type temperature automatic expansion valve is provided in the refrigerant circuit as a configuration of the refrigeration apparatus, and the external pressure equalizing pipe of the automatic expansion valve is provided. A part is connected to a part of the high pressure line with a high pressure introduction pipe, and the automatic expansion valve side passage of the external pressure equalizing pipe is switched between the suction line side and the high pressure introduction pipe side in conjunction with the start and stop of the compressor. A mechanism was provided and the external pressure equalizing tube was inclined downward from the automatic expansion valve side toward the suction line side.
Even if liquid refrigerant is generated in the external pressure equalizing pipe, it can be discharged to the suction line, and therefore, the risk of low pressure cut during starting of the compressor can be effectively prevented.

According to a second aspect of the present invention, in the first aspect of the present invention, a plurality of sets of the evaporator and the automatic expansion valve are provided, and an external pressure equalizing pipe of each automatic expansion valve is merged with a common main pipe to form a suction pipe and an automatic expansion valve. Since the switching mechanism is connected to the high-pressure introduction pipe and the switching mechanism is disposed below the lowermost automatic expansion valve, the effect of the first aspect of the invention can be obtained with a single switching mechanism and the high-pressure introduction pipe. Therefore, it is possible to reduce the cost while ensuring the smooth start of the compressor.

According to the third aspect of the present invention, in the first or second aspect of the present invention, the heat exchange between the refrigerant in the passage of the external pressure equalizing pipe on the side of the automatic expansion valve and the liquid refrigerant in the liquid pipe of the refrigerant circuit is performed. Since the heat exchanger is provided, it is possible to suppress the generation of the liquid refrigerant in the external pressure equalizing tube, and thus the above-described inventions can exert the remarkable effects.

[Brief description of the drawings]

FIG. 1 is a refrigerant piping system diagram of a refrigeration apparatus according to an embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Compressor 2 Condenser 4 Auxiliary heat exchanger 5 Automatic expansion valve 6 Evaporator 7a Low pressure line 8 Main refrigerant circuit 10 External pressure equalization pipe 11 High pressure introduction pipe 12 Three-way switching valve (switching mechanism)

Claims (3)

(57) [Claims] 1. A refrigeration system having a main refrigerant circuit (8) in which a compressor (1), a condenser (2), an external pressure equalizing type automatic temperature expansion valve (5), and an evaporator (6) are sequentially connected. In the above, the external pressure equalizing pipe (10) of the automatic expansion valve (5) connected to the suction line (7a) of the main refrigerant circuit (8), one part of the external pressure equalizing pipe (10) and one on the high pressure line The high pressure introduction pipe (11) connecting the parts and the automatic expansion valve side passage of the external pressure equalizing pipe (10) are connected to the suction line (7a) side with the high pressure introduction in conjunction with the start / stop of the compressor (1). A switching mechanism (12) for switching to communicate with the pipe (11), and the automatic expansion valve (5), a switching mechanism (12),
The connection between the pressure equalizing pipe (10) and the suction line (7a)
It is arranged so that the next height position is lower, and
Expansion valve (5), switching mechanism (12) and suction line (7
The external pressure equalizing pipe (10) connecting a) is an automatic expansion valve.
(5) Tilting downward from the suction line (7a) side
A refrigeration device characterized by being inclined . 2. The refrigeration apparatus according to claim 1, wherein a plurality of sets of the evaporator (6) and the automatic expansion valve (5) are provided,
External pressure equalizing pipe (10a-1) of each automatic expansion valve (5a-5c)
0c) is connected to the suction line (7a) and the high-pressure introduction pipe (11) via a common main pipe (10) after the merging, and the switching mechanism (12) is connected to the lowermost automatic expansion valve (5c). A refrigeration apparatus characterized in that the refrigeration apparatus is also installed below. 3. The refrigeration system according to claim 1, wherein a portion constituting an automatic expansion valve side passage of the external pressure equalizing pipe (10) and an automatic expansion valve (5) of a main refrigerant circuit (8). A refrigeration system comprising an auxiliary heat exchanger (4) that straddles an upstream liquid pipe and exchanges heat between refrigerants in both pipes.