JPH10141811A - Oil separator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To actively return refrigerator oil separated from a refrigerant in an evaporator without permitting the oil to stay in the evaporator. SOLUTION: A refrigerant piping 13 of a heat exchanger 15 constituting an evaporator 1 is disposed from the upstream side to the downstream side in a serpentine manner directed upward, and a plurality of parallel parts 21 are communicated with each other through a U bent part 23. To a lower part of the U bent part 23 an oil introduction pipe 25 for leading refrigerator oil is connected, and separated refrigerator oil is returned to a compressor. In the U bent part 23, the oil is likely to be separated with gravity and centrifugal force, and hence the function of an oil separator is ensured naturally.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a refrigeration apparatus,
More specifically, the present invention relates to a structure of an oil separator for returning refrigeration oil separated from a refrigerant to a compressor.

[0002]

2. Description of the Related Art Generally, a refrigeration system (in this specification, a concept including a refrigeration system) is used in a wide range of fields such as cooling inside a showcase and a refrigerator.

FIG. 3 shows a general refrigerant circuit diagram of such a refrigerating apparatus. That is, the refrigerant evaporated in the evaporator 1 is
The refrigerant is sent to the accumulator 3 and temporarily stored until the refrigerant liquid that has not completely evaporated out of the refrigerant evaporates. Only the evaporated refrigerant gas is sent to the compressor 5 and compressed to be a high-temperature and high-pressure refrigerant gas. The high-temperature and high-pressure refrigerant gas exchanges heat with surrounding air in the condenser 7 to be cooled and condensed. The condensed refrigerant liquid is sent to the dryer 9 and excess water present in the refrigerant is adsorbed by an adsorbent such as zeolite. Thereafter, the refrigerant is passed through the capillary tube 11 to be decompressed, and sent to the evaporator 1 again.

[0004] As a refrigerant, H does not destroy the ozone layer.
FC (hydroflurocarbon) based refrigerant (for example, HF
C-134a) is to be used. Also,
In the refrigerating device, refrigerating machine oil used for lubrication of the compressor 5 and the like is used in a state of being mixed with and melted by the refrigerant.
As the refrigerating machine oil when an HFC-based refrigerant is used, it is usual to use, for example, an ester, PAG (polyalkylene glycol oil) or the like as the refrigerating machine oil compatible with the refrigerant.

[0005] However, these refrigerating machine oils are highly hygroscopic and deteriorate due to the presence of moisture to generate sludge. This sludge adheres to the capillary tube 11 and the like, and tends to cause a decrease in the cooling performance of the refrigeration apparatus by alienating the flow of the refrigerant. Therefore, in order to operate the refrigeration apparatus stably, it is necessary to control water, impurities, and the like that cause sludge to a low level. Also, in the service work in the market, it is necessary to control moisture, impurities, and the like to a low level, and the workability is much worse than the conventional work.

On the other hand, conventional refrigeration oils (alkylbenzene oil and mineral oil) used in conventional refrigerants (such as R22) that are not HFC-based refrigerants are less controlled than refrigeration oils that are more compatible with the HFC-based refrigerants. There was no need to be strict. For this reason, it is desirable that conventional refrigeration oil can be used if possible.

[0007]

However, when the conventional refrigerating machine oil is used for the HFC-based refrigerant, the refrigerating machine oil discharged from the compressor is separated and stays in the refrigerant pipe due to poor compatibility, and the refrigerating machine oil is rejected. Insufficient oil may cause insufficient lubrication of the compressor, causing a so-called oil shortage.

Particularly, in an evaporator in which the refrigerant evaporates, the refrigerant and the refrigerating machine oil are easily separated, and further, the viscosity of the separated refrigerating machine oil increases due to a decrease in temperature due to the evaporation of the refrigerant. It gets worse, and the stay gets worse.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and it is possible to positively return the refrigerating machine oil separated from the refrigerant in the evaporator to the compressor without staying in the evaporator. It is intended to provide a separator.

[0010]

Means for Solving the Problems To achieve the above object, according to the first aspect of the present invention, a refrigerant gas evaporated by an evaporator is compressed into a high-temperature and high-pressure refrigerant gas by a compressor.
A refrigerant flow path for returning the refrigerant condensed by heat exchange with the surrounding air in the condenser to the evaporator again, provided in a refrigerating apparatus in which refrigerant and refrigerating machine oil for lubricating the compressor are mixed, In the oil separator for separating the refrigerating machine oil from the above, the refrigerant flow path of the heat exchanger constituting the evaporator is arranged to meander upward from the upstream side to the downstream side, and the refrigerant flow paths are parallel to each other. Is connected by a U vent portion, and an oil guide pipe for guiding refrigerating machine oil is connected to a lower portion of the U vent portion, and the oil guide tube is connected to a compressor, which is an oil separator.

According to the invention of claim 2, the U vent portion is a double pipe, and the refrigerant flows into the inner pipe constituting the double pipe, and the inner pipe has a mesh structure. The oil separator according to claim 1, wherein an oil guide pipe is connected to the outer pipe.

According to a third aspect of the present invention, there is further provided an oil pipe in which at least a lower portion of the U vent portion is formed as an oil reservoir and the oil guide is connected to the oil reservoir. Oil separator.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 2, the evaporator 1 in which the refrigerant liquid evaporates and supplies cold heat is provided by a refrigerant pipe 13.
Is connected to the accumulator 3. The accumulator 3 is a container for temporarily storing and evaporating the refrigerant liquid that has not been completely evaporated in the evaporator 1. Accumulator 3
Is connected through a refrigerant pipe 13 to a compressor 5 which compresses the refrigerant gas into a high-temperature and high-pressure refrigerant gas. The compressor 5 is connected via a refrigerant pipe 13 to a condenser 7 that cools a high-temperature and high-pressure refrigerant gas with air. The condenser 7 is a refrigerant pipe 1
Through 3, it is connected to a dryer 9 and further connected to a capillary tube 11 for reducing the pressure of the refrigerant liquid.

As the refrigerant, an HFC-based refrigerant having a low risk of destruction of the ozone layer is used, and as the refrigerating machine oil, a conventional refrigerating machine oil which does not need to be strictly controlled, although it has poor compatibility with this refrigerant, is used. You.

As shown in FIG. 1, for example, a fin tube type heat exchanger 15 constituting the evaporator 1 is arranged such that a refrigerant pipe 13 through which a refrigerant passes passes through a large number of fins 19 while meandering. This meandering refrigerant pipe 13
In the refrigerant pipe 13, a plurality of mutually parallel portions 21 are connected to each other by U-vent portions 23 in the refrigerant pipe 13.

An oil guide pipe 25 is connected to a lower portion of some of the U vent portions 23, that is, to a portion where a U-shaped curve starts. Some of these U vent portions 23
As shown in FIG. 1 (B, D, E), it is a double pipe 29, the inner pipe 31 has a mesh structure 33, and the oil guide pipe 25 is connected to the outer pipe 35. The horizontal cross section of the double pipe 29 can be as shown in FIG. 1 (D) or (E).

The oil guide pipe 25 is for guiding the refrigerating machine oil separated from the refrigerant. These oil guide pipes 25 join the oil guide main pipe 27 and are connected to an operating part of the compressor 5, that is, a part requiring lubrication.

Thus, the oil separator 36 is formed.

Next, the operation of this embodiment will be described.

First, the refrigerant liquid evaporates in the evaporator 1 to become a refrigerant gas. At this time, heat is taken off as heat of vaporization, and a cooling function is performed. The evaporated refrigerant gas is sent to the accumulator 3, and the refrigerant liquid contained in the refrigerant gas and not completely evaporated is temporarily stored. The stored refrigerant liquid evaporates and becomes refrigerant gas. The refrigerant liquid is temporarily stored, and the evaporated refrigerant gas flows to the compressor 5, so that the refrigerant liquid does not directly enter the compressor 5 and is compressed. The refrigerant gas from the accumulator 3 is compressed by the compressor 5 and becomes a high-temperature and high-pressure refrigerant gas. The high-temperature and high-pressure refrigerant gas exchanges heat with surrounding air in the condenser 7 and is cooled.
The cooled and condensed refrigerant liquid is sent to the dryer 9, where excess water present in the refrigerant is adsorbed and removed. Then, the pressure is further reduced through the capillary tube 11.
The decompressed refrigerant liquid is sent to the evaporator 1 again.

The refrigerant leaving the compressor 5 contains refrigerating machine oil used for lubricating the compressor 5. This refrigerating machine oil has poor compatibility with the refrigerant, and has a refrigerant circuit, especially an evaporator 1.
While flowing through the refrigerant pipe 13, it is separated from the refrigerant. As the amount to be separated increases, the amount of refrigerating machine oil inside the compressor 5 decreases.

At this time, the refrigerant flows inside the refrigerant pipe 13 of the heat exchanger 15 constituting the evaporator 1. Then, the refrigerant changes its flow direction along the U-shape while going upward at the U vent portion 23. For this reason, the refrigeration oil separated from the refrigerant in the evaporator 1 acts on the U-vent portion 23 when gravity moves upward and is pushed back downward, and further, centrifugal force acts outward due to the U-shaped curve. It is pushed toward the inner wall on the outer peripheral side of the vent portion 23.
The refrigerating machine oil is separated from the refrigerant by such gravity and centrifugal force.

Then, the separated refrigerating machine oil 37 is collected by the mesh structure constituting the double pipe 29 of the U vent portion 23, even if it is separated and still floats. The collected refrigerating machine oil passes through the inner tube 31 having the mesh structure, moves to the outer tube 35, and stores the oil in the lower portion of the outer tube 35.
Collect at 9. Thereafter, the refrigerant gas is returned to the compressor 5 through the oil guide pipe 25 due to the wind pressure or pressure difference of the refrigerant gas.

As described above, according to this embodiment, the following effects can be obtained. That is, the refrigerating machine oil separated from the refrigerant flows toward the outer pipe 35 side at the U vent portion 23 due to gravity and centrifugal force, and the amount of the refrigerating machine oil flowing downstream from the U vent portion 23 can be reduced. U
Since the oil is guided to the oil guide pipe 25 connected to the vent portion 23 and returns to the compressor 5, it is possible to prevent the compressor 5 from running out of oil.

In the lower part of the U vent portion 23,
The outer pipe 35 constituting the double pipe 29 has a larger diameter than the meandering parallel part 21 of the refrigerant pipe 13, and a lower part of the expanded part forms an oil reservoir 39. . By the function of the oil sump 39, even if a large amount of refrigerating machine oil is temporarily separated, the oil is accumulated in the oil sump 39,
It is possible not to exceed the U-vent portion 23.

(Other Embodiments) In the above embodiment, the U vent portion 23 is a double pipe 29 and the inner pipe 3
Although 1 is the mesh structure 33, in other embodiments, such a double tube 29 is not necessarily required. It is also possible to simply adopt a structure in which an oil guide pipe is connected to the lower part of the U vent portion 23 (FIG. 1).
(C)).

In the above embodiment, the diameter of the U-vent portion 23 is enlarged, so that the lower portion of the U-vent portion 23 becomes the oil reservoir 39. However, in other embodiments, the diameter of the U-vent portion 23 is increased. Instead, it is also possible to form the oil reservoir by other means. For example, the lower part of the U-vent portion may be partially expanded. Further, such an oil reservoir 39 may not be provided.

In the above embodiment, the heat exchanger 15 constituting the evaporator 1 has the refrigerant pipe 13 having a large number of fins 1.
Although a fin tube type having a structure penetrating through the fin tube 9 has been described as an example, in another embodiment, a U-type is used in a roll-bond type or a tube-on-sheet type in which a flow path as a refrigerant pipe is formed between bonded metal plates. The present invention can be implemented in an evaporator employing a heat exchanger capable of forming a vent portion.

In the above embodiment, the oil guide main pipe 27 is used.
Was always in communication with the compressor 5, but in other embodiments, a solenoid valve was provided in the middle of the oil guide main pipe, and the solenoid valve was controlled to open only when the refrigeration system was defrosted or when the thermostat was turned off. It is possible to By doing so, the diameter of the oil guide pipe 25 and the oil guide main pipe 27 can be made sufficiently large, and the refrigerating machine oil can be quickly and easily returned to the compressor 5.

[0030]

As described above, according to the first to third aspects of the present invention, when the refrigerant is meandered upward from the upstream side to the downstream side in the refrigerant pipe of the evaporator, The refrigerating machine oil separated from the refrigerant falls into the oil guide pipe connected to the lower part of the U vent portion due to gravity or centrifugal force, and is positively returned to the compressor due to a pressure difference or the like.

According to the invention of claim 2, the refrigerant is U
It flows into the inner pipe constituting the double pipe of the vent portion, moves from the mesh structure of the inner pipe to the outer pipe, and is easily guided by the oil guide pipe.

According to the third aspect of the present invention, since the lower portion of the U-vent portion where the separated refrigerating machine oil is apt to fall is pooled, the dropped refrigerating machine oil temporarily accumulates in the oil pool. In addition, since it is guided by the oil guide pipe, even if a large amount of refrigerating machine oil is separated, it can be sufficiently returned to the compressor 5.

[Brief description of the drawings]

FIG. 1A is a side view showing an oil separator provided in a heat exchanger constituting an evaporator of a refrigeration apparatus according to one embodiment of the present invention, and FIG. 1B is an enlarged view of a main part of FIG. Figure,
(C) is a diagram showing a modification of (B), (D) is a view taken in the direction of (B), and (E) is a diagram showing a modification of (D).

FIG. 2 is a refrigerant circuit diagram of a refrigeration apparatus having the evaporator of FIG.

FIG. 3 is a refrigerant circuit diagram of a conventional refrigeration apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Evaporator 3 Accumulator 5 Compressor 7 Condenser 9 Capillary tube 13 Refrigerant piping 21 Parallel part 23 U vent part 25 Oil guide pipe 27 Oil guide main pipe 29 Double pipe 31 Inner pipe 35 Outer pipe 36 Oil separator 37 Refrigerator oil 39 Oil pool

Claims (3)

[Claims] 1. A refrigerant flow in which a refrigerant gas evaporated in an evaporator is compressed by a compressor into a high-temperature and high-pressure refrigerant gas, and a refrigerant that exchanges heat with ambient air in a condenser and returns the condensed refrigerant to the evaporator again. An oil separator provided in a refrigerating device, wherein the refrigerating machine oil for lubricating the compressor and the refrigerant coexists, and separating the refrigerating machine oil from the refrigerant, a refrigerant flow path of a heat exchanger constituting an evaporator The refrigerant flow path is arranged to meander upward from the upstream side to the downstream side, and a plurality of parallel portions of the refrigerant flow path are communicated with each other by a U-vent portion. An oil separator, wherein an oil pipe is connected, and the oil guide pipe is connected to a compressor. 2. The U-vent part is a double pipe,
2. The oil separator according to claim 1, wherein the refrigerant flows into an inner tube constituting the double tube, the inner tube has a mesh structure, and an oil guide tube is connected to the outer tube. 3. The oil separator according to claim 1, wherein at least a lower portion of the U vent portion is an oil reservoir, and an oil guide pipe is connected to the oil reservoir.