JPH10148423A - Refrigerating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent danger of a running out of oil from generating by a method wherein among refrigerant pipings where a refrigerant is passed to a heat-exchanger which constitutes an evaporator, at least areas where a refrigerating machine oil is easy to separate from the refrigerant are made a double pipe, and the refrigerant is passed on the external side, and a high temperature refrigerant gas from a compressor is branched and guided to the internal side. SOLUTION: To a refrigerant piping 11C of a compressor 5, a pipe 13 for high pressure gas, which guides a refrigerant gas of a high temperature to an evaporator 1, is connected, and by providing an electromagnetic valve 15 on an outward path, and a check valve 17 on a returning path, a reverse flow is prevented from generating. The pipe 13 for high pressure gas is branched into a plurality of branching pipes in parallel, and also, in a heat-exchanger, the refrigerant piping is arranged in a manner to meander while going through a large number of fins. By inserting the branching pipe in the refrigerant piping, the refrigerant piping becomes a double pipe, and the refrigerant passes through the external side, and the refrigerant pipe has a function to cool the evaporator 1. Also, on the internal side, the high temperature refrigerant gas is guided. Then, in the evaporator 1, the refrigerating machine oil stays, and is heated by the high temperature refrigerant gas, and the viscosity of the refrigerating machine oil increases, and the flowability is recovered, and the refrigerating machine oil is returned to the compressor 5.

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 evaporator constituting a part of a refrigeration apparatus.

[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. 4 shows a general refrigerant circuit diagram of such a refrigeration system. 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 reduced in pressure through the capillary tube 9 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 9 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 has as its object to provide a refrigeration apparatus which can prevent refrigeration oil from separating and staying in a refrigerant in an evaporator.

[0010]

SUMMARY OF THE INVENTION In order to achieve the above object, according to the first aspect of the present invention, a refrigerant gas evaporated by an evaporator is compressed by a compressor into a high-temperature and high-pressure refrigerant gas, and the refrigerant gas is compressed by a condenser. In a refrigerating apparatus including a refrigerant flow path for returning the refrigerant condensed by exchanging heat with the surrounding air to the evaporator again, wherein the refrigerant and the refrigerating machine oil for lubricating the compressor are mixed, the heat forming the evaporator is provided. At least a part of the refrigerant pipe through which the refrigerant passes through the exchanger is formed as a double pipe at a portion where the refrigerating machine oil is easily separated from the refrigerant, the refrigerant is passed outside the double pipe, and the high-temperature refrigerant gas from the compressor is passed inside. Is a refrigeration apparatus characterized by diverting and guiding.

According to a second aspect of the present invention, a high pressure gas pipe for guiding a high-temperature refrigerant gas to the inside of the double pipe is provided with a solenoid valve, a compressor is provided with an oil level sensor, or the evaporator and the compressor are connected to each other. An oil level sensor is provided in an accumulator provided between the compressor and a control unit for opening the solenoid valve when the level of the refrigerating machine oil detected by the oil level sensor reaches a predetermined value, and guiding high-temperature refrigerant gas. The refrigeration apparatus according to claim 1, characterized in that:

According to a third aspect of the present invention, a high-pressure gas pipe for guiding a high-temperature refrigerant gas is provided inside the double pipe, and a solenoid valve is provided. 2. The refrigeration apparatus according to claim 1, further comprising control means for opening an electromagnetic valve to guide a high-temperature refrigerant gas.

According to a fourth aspect of the present invention, the high-pressure gas pipe for introducing the high-temperature refrigerant gas is branched into a plurality of parallel branch pipes, and the branch pipes are parallel to each other in the zigzag refrigerant pipes. The electromagnetic valve is provided in each branch pipe, the electromagnetic valve is sequentially opened from the upstream side of the refrigerant pipe, and control means for guiding the high-temperature refrigerant gas in parallel is provided. A refrigeration apparatus according to 1, 2, or 3.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIGS. The evaporator 1 in which the refrigerant liquid evaporates and supplies cold heat is connected to the accumulator 3 via the refrigerant pipe 11A. The accumulator 3 is a container for temporarily storing and evaporating the refrigerant liquid that has not been completely evaporated in the evaporator 1. The accumulator 3 is a refrigerant pipe 11B
Is connected 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 11C to a condenser 7 that cools a high-temperature and high-pressure refrigerant gas with air. The condenser 7 is connected via a refrigerant pipe 11D to a capillary tube 9 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 has poor compatibility with this refrigerant but does not require strict control is used.

The refrigerant pipe 11C on the downstream side of the compressor 5 includes:
High-pressure gas pipe 1 for guiding high-temperature refrigerant gas to evaporator 1
3 are connected. The solenoid valve 1 is provided on the outward path of the high pressure gas pipe 13.
5 is provided, and a check valve 17 is provided on the return path so that the refrigerant gas does not flow backward from the compressor 5 side.

Then, as shown in FIG.
3 branches into a plurality of parallel branch pipes 19. In the heat exchanger 21 constituting the evaporator 1, the refrigerant pipe 11
Is meanderingly piped while penetrating a number of fins (not shown). Then, the branch pipe 19 is inserted into each of a plurality of parallel portions 23 of the refrigerant pipe 11 arranged in a meandering manner (FIG. 2B). Portion 24 where this insertion is performed
Are welded. Each branch pipe 19 is provided with a solenoid valve 25. The plurality of solenoid valves 25 are also opened and closed (ON, OFF) by the control device 31.

The branch pipe 19 serves as the refrigerant pipe 11 of the evaporator 1.
, The refrigerant pipe 11 is a double pipe 27 (FIGS. 2B and 2C). The refrigerant passes outside the double pipe 27. Since this refrigerant has a function of cooling the evaporator 1, it is cold. A high-temperature refrigerant gas is guided inside the double pipe 27.

As shown in FIG. 1, an oil level sensor 29 for detecting the level of refrigerating machine oil inside the compressor 5 is provided.
Is provided. The detected value is sent to the control device 31, and the solenoid valve 15 of the high pressure gas pipe 13 and the solenoid valve 25 of the branch pipe 19 are output by the output from the control device 31 based on the detected value.
Are opened and closed (ON, OFF).

That is, when the level of the refrigerating machine oil in the compressor 5 becomes smaller than a predetermined value, the solenoid valve 15 is opened, and each solenoid valve 25 of the branch pipe 19 is connected to the refrigerant pipe 11 (double pipe 27). Opened in order from the one located upstream.

Hereinafter, the operation of this embodiment will be described. First, the refrigerant evaporates in the evaporator 1 into a refrigerant gas. At this time, the heat of vaporization performs a cooling function. 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. By temporarily storing the refrigerant liquid and evaporating the refrigerant gas to the compressor 5, the refrigerant liquid can be prevented from directly entering the compressor 5 and compressing the liquid. 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 decompressed through the capillary tube 9. The decompressed refrigerant liquid is sent to the evaporator 1 again.

The refrigerant that has left the compressor 5 contains refrigerating machine oil used for lubricating the compressor 5. This refrigerating machine oil separates as the liquid refrigerant evaporates inside the heat exchanger 21 constituting the evaporator 1, and flows through the refrigerant pipe 11 by the refrigerating machine oil alone. In such a state, normally, the wind pressure of the refrigerant gas keeps the refrigerating machine oil flowing, and returns to the compressor 5. However, as the temperature decreases due to the operation of the evaporator 1, the viscosity of the refrigerating machine oil increases, so that the refrigerating machine oil becomes difficult to flow and eventually stays. When this stagnation state continues, the amount increases, the amount of the refrigerating machine oil returning to the compressor 5 decreases, the total amount of the refrigerating machine oil in the compressor 5 decreases, and thus the lubrication of the compressor 5 deteriorates, The danger of running out of oil in the compressor 5 increases.

As described above, when the amount of refrigerating machine oil inside the compressor 5 decreases, the oil level sensor 29 detects the level of the refrigerating machine oil, and when the detected level becomes lower than a predetermined value, the control unit to which the detected value is input. 31 is the hot gas pipe 1
The solenoid valve 15 of No. 3 is opened. As a result, high-temperature refrigerant gas is diverted from the refrigerant pipe 11 downstream of the compressor 5, and
Led to. Since the electromagnetic valve 15 is opened intermittently in this manner, it is possible to suppress an unnecessary increase in the temperature of the evaporator 1.

In the evaporator 1, the refrigerant pipe 11
A high-temperature refrigerant gas is introduced into the inside of the double pipe 27. A refrigerant is passed through the outside of the double pipe 27, and the refrigerant oil 33 (FIG. 2)
(C)) is staying. The refrigerating machine oil 33 is warmed by the high-temperature refrigerant gas, the viscosity increases, and the fluidity is restored. The refrigerating machine oil that has become easier to flow in this way is returned to the compressor 5 by the wind pressure of the refrigerant gas or the like.

Although the refrigerating machine oil flowing to the compressor 5 enters the accumulator 3, it is considered that the viscosity of the refrigerating machine oil also decreases because the temperature of the accumulator 3 increases. Therefore, it is easy to return to the compressor together with the refrigerant gas from the accumulator 3.

As described above, since the refrigerating machine oil is prevented from staying inside the evaporator 1, the total amount returning to the compressor 5 increases, and the risk of running out of oil is reduced.

Further, by guiding the high-temperature refrigerant gas inside the double pipe 27 and passing the refrigerant outside, the inner pipe, that is, the refrigerant pipe 11 is efficiently heated, and therefore, the refrigerating machine oil separated from the refrigerant and staying therein is retained. 33 can be efficiently heated to restore fluidity.

(Other Embodiments) In the above embodiment, the oil level sensor 29 is provided in the compressor 5, but in other embodiments, the oil level sensor 35 may be provided in the accumulator 3. The oil level sensor 35 provided inside the accumulator 3 can detect the level by using a specific gravity difference between the refrigerant liquid separated into two phases and the refrigerating machine oil in the accumulator 3. That is, the level can be detected by using a float having a specific gravity that allows the refrigerant liquid to float below the refrigerating machine oil at the upper boundary between the two layers, and detecting the position of the float.

When the refrigerating machine oil separates and stays, most of the refrigerant becomes a refrigerant gas in the evaporator 1, and the separated refrigerating machine oil flows only by the wind pressure of the refrigerant gas. In such a case, since there is little liquid refrigerant in the accumulator 3, the level of only the refrigerating machine oil may be detected.

When the refrigerating machine oil stays in the evaporator 1 or the like, the amount of the refrigerating machine oil in the accumulator 3 decreases. When the detected level of the refrigerating machine oil decreases, the solenoid valve 15 of the high-temperature gas pipe 13 is opened.

In the above embodiment, the evaporator 1
Most of the refrigerant pipes 11 are the double pipes 27,
In another embodiment, it is also possible to form a double pipe only partially. That is, it is also possible to select only a part of the refrigerant pipe 11 of the evaporator 1 where the refrigerating machine oil is easily separated from the refrigerant, and to form a double pipe.

In the above embodiment, the solenoid valve 15 for guiding the high-temperature refrigerant gas is opened and closed according to the detection value of the oil level sensor 29. And can be opened and closed by a timer. That is, the operation time of the refrigeration system is monitored by a timer, the time in which the refrigerating machine oil will be separated from the refrigerant by a predetermined amount is predicted in advance, and when the time has elapsed, the control device controls the solenoid valve 15 for a predetermined short time. It is possible to introduce a high-temperature refrigerant gas.

In the above-described embodiment, the solenoid valves 25 provided in the plurality of branch pipes 19 are opened in order, so that the refrigerating machine oil 3 which has been efficiently retained by a small amount of the refrigerant gas.
3 is heated, but it is not always necessary to provide such a solenoid valve 25 in other embodiments, and it is also possible to simultaneously guide the high-temperature refrigerant gas to the plurality of branch pipes 19. By omitting the solenoid valve 25, the cost of the device can be reduced.

In the above-described embodiment, the refrigerating machine oil whose fluidity has been restored passes through a normal refrigerant circuit, is returned to the compressor 5, is stored in the accumulator 3, and is evaporated again by the accumulator 3. It was dissolved in the refrigerant and returned to the compressor 5 together with the refrigerant.

However, in another embodiment, as shown in FIG. 3, high-temperature and high-pressure refrigerant gas from the compressor 5 is transferred to the refrigerating machine oil and the refrigerant liquid (separated into two layers) stored in the accumulator 3. Is stirred and mixed again to make them compatible with each other, whereby the refrigerating machine oil accumulated in the accumulator 3 can be positively returned to the compressor side. Therefore, the refrigerant pipe 11 on the downstream side of the compressor 5 and the accumulator 3 are connected by a second high-pressure gas pipe 37, and an electromagnetic valve 39 is provided in the second high-pressure gas pipe 37 (FIG. 3).

[0036]

As described above, according to the first to fourth aspects of the present invention, the high temperature refrigerant gas guided from the compressor warms the refrigerant pipe at the portion where the refrigerating machine oil is easily separated from the refrigerant. The viscosity of the separated and retained refrigerating machine oil is reduced to restore the fluidity, thereby enabling the refrigerating machine oil to be returned to the compressor together with the refrigerant.

According to the second aspect of the present invention, since the oil level sensor detects that the level of the refrigerating machine oil has reached a predetermined value, the solenoid valve is opened to guide the high-temperature refrigerant gas. The double tube can be warmed only when necessary, and unnecessary temperature rise of the evaporator can be suppressed.

Further, according to the third aspect of the present invention, the operation time of the refrigeration system is monitored by the timer, and the high-temperature refrigerant gas is intermittently introduced to warm the refrigerant pipe, so that the temperature of the evaporator rises unnecessarily. Can be suppressed.

According to the fourth aspect of the present invention, the solenoid valve is opened in order from the upstream side of the refrigerant pipe, and the high-temperature refrigerant gas is sequentially led to a plurality of portions of the refrigerant pipe parallel to each other. With the high-temperature refrigerant gas, the refrigerant pipes can be efficiently warmed in order, and unnecessary temperature rise of the evaporator can be suppressed. By sequentially warming from the upstream side, the refrigerating machine oil whose fluidity has been recovered can be expected to return to the compressor by involving the refrigerating machine oil of the downstream side that has not yet recovered the fluidity.

[Brief description of the drawings]

FIG. 1 is a refrigerant circuit diagram showing one embodiment of the present invention.

2 (A) is an overall schematic view of a heat exchanger constituting the evaporator of FIG. 1, (B) is an enlarged view of a main part of (A), and (C) is a sectional view of (B).

FIG. 3 is a refrigerant circuit diagram showing another embodiment of the present invention.

FIG. 4 is a refrigerant circuit diagram showing a conventional refrigeration apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Evaporator 3 Accumulator 5 Compressor 7 Condenser 9 Capillary tube 13, 37 High-pressure gas pipe 15, 25, 39 Solenoid valve 17 Check valve 19 Branch pipe 27 Double pipe 29, 35 Oil level sensor 31 Controller

Claims (4)

[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. In a refrigeration system that includes a refrigerant passage and refrigerant oil for lubricating the compressor, at least the refrigerant oil is separated from the refrigerant in the refrigerant pipe that passes the refrigerant through the heat exchanger that constitutes the evaporator. A refrigerating apparatus, wherein the easy part is a double pipe, a refrigerant is passed through the outside of the double pipe, and a high-temperature refrigerant gas from the compressor is split and guided inside the double pipe. 2. A high pressure gas pipe for guiding a high-temperature refrigerant gas inside the double pipe is provided with a solenoid valve, a compressor is provided with an oil level sensor, or provided between the evaporator and the compressor. 2. The accumulator is provided with an oil level sensor, and control means for opening the solenoid valve and guiding high-temperature refrigerant gas when the level of the refrigerating machine oil detected by the oil level sensor reaches a predetermined value is provided. Refrigeration equipment. 3. A high-pressure gas pipe for introducing a high-temperature refrigerant gas inside the double pipe is provided with an electromagnetic valve, and the operation time of the refrigeration system is monitored by a timer, and the electromagnetic valve is intermittently opened to open the high-temperature refrigerant. 2. The refrigeration apparatus according to claim 1, further comprising control means for guiding gas. 4. A high-pressure gas pipe for guiding a high-temperature refrigerant gas is branched into a plurality of parallel branch pipes, and this branch pipe is inserted into each of a plurality of mutually parallel portions of a refrigerant pipe arranged in a zigzag manner. An electromagnetic valve is provided in each branch pipe, and control means for opening the electromagnetic valve in order from the upstream side of the refrigerant pipe and guiding the high-temperature refrigerant gas in parallel in order is provided.
Or the refrigeration apparatus according to 3.