JPH08240350A - Freezing cycle - Google Patents

Abstract

PURPOSE: To prevent liquid refrigerant from being sucked into a compressor in a freezing cycle in which refrigerant having, as its main substance, hydroflorocarbon, and refrigerating machine oil not or scarcely compatible with the refrigerant are provided. CONSTITUTION: There are provided a compressor 1, a condenser 2, an expansion mechanism 3, an evaporator 4, a blower 9 for blowing air to the evaporator 4, refrigerant having, as its major substance, hydrofluorocabon, refrigerating machine oil 7 not or scarcely compatible with the refrigerant, a header 18 having a suction pipe 11 acting as a pipe extending from the compressor 1 connected to its upper part and another pipe extending from the evaporator 4 connected to its lower part, and an oil returning mechanism 12 connected between the expansion mechanism 3 and the evaporator 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerating and air-conditioning system using a refrigerant containing hydrofluorocarbon as a main component.

[0002]

2. Description of the Related Art A conventional refrigeration cycle using HFC134a, which is a hydrofluorocarbon, as a refrigerant is disclosed in Japanese Patent Laid-Open No. 5-157379.

A conventional refrigeration cycle will be described with reference to the drawings. In FIG. 4, 1 is a compressor, 2 is a condenser for condensing the refrigerant gas discharged from the compressor, 3 is a capillary tube as an expansion mechanism, 4 is an evaporator, 5 is an outlet of the evaporator 4 to the upper side. And a suction pipe 6 which is inserted into the header 5 from the lower side of the header 5 and extends upward.

Numeral 7 is a refrigerating machine oil which lubricates sliding parts in the compressor, which may be hard alkylbenzene oil, soft alkylbenzene oil having excellent low-temperature fluidity, polyalphaolefin, paraffinic mineral oil, naphthenic mineral oil or the like alone or Some are mixed and have little or no mutual solubility with a refrigerant such as HFC134a containing hydrofluorocarbon as a main component. Reference numeral 8 is an oil return hole provided on the upper side surface of the suction pipe 6 inserted into the header 5.

Next, the operation will be described. The refrigerant discharged from the compressor 1 is condensed in the condenser 2, expanded under reduced pressure in the capillary tube 3, evaporated in the evaporator 4, and the refrigerant that cannot be completely evaporated in the evaporator 4 is stored in the header 5. ,
Only the gas phase component is sucked into the compressor 1 through the suction pipe 6. At this time, the refrigerating machine oil 7 is discharged from the compressor 1 together with the refrigerant, flows in the pipe, and reaches the evaporator 4.

The refrigerating machine oil 7 flows in the evaporator 4 together with the refrigerant that evaporates and vaporizes, and enters the header 5 or is stored in the header 5 together with the liquid refrigerant stored therein. Here, since the specific gravity of the refrigerating machine oil 7 is lighter than that of the liquid refrigerant and there is no mutual solubility with the refrigerant, the refrigerant and the refrigerating machine oil 7 are separated into two phases, and the refrigerating machine oil 7 floats on the liquid refrigerant. Becomes

When the liquid level of the refrigerating machine oil 7 reaches the oil return hole 8, the refrigerating machine oil 7 is sucked into the suction pipe 6 through the oil return hole 8 and is sucked into the compressor 1.

[0008]

However, in the above conventional configuration, when the load on the evaporator 4 is extremely small,
There is a risk that the liquid refrigerant stored in the header 5 becomes excessive, the liquid refrigerant is sucked together with the refrigerating machine oil 7, and liquid compression occurs in the compressor 1.

When the load is extremely large, the amount of liquid refrigerant stored in the header-5 decreases and the oil level of the refrigerating machine oil 7 does not reach the oil return hole 8. Therefore, the refrigerating machine oil 7 does not return to the compressor 1 and the compressor 1 Since the refrigerating machine oil 7 in 1 is insufficient, the sliding portion wear of the compressor is increased, which is a big problem in the life and reliability of the compressor.

In view of the above problems, it is an object of the present invention to provide a refrigeration cycle in which refrigerating machine oil is recovered.

[0011]

Therefore, the refrigeration cycle of the present invention comprises a compressor, a condenser, an expansion mechanism, an evaporator, and
A refrigeration cycle in which these are sequentially connected in a ring, a refrigerant containing hydrofluorocarbon as a main component, refrigerating machine oil that has no or little mutual solubility with the refrigerant, and a suction pipe that is a pipe from the compressor is provided at the top. The header from which the pipe from the evaporator is connected to the lower part, and the oil return mechanism connected between the expansion mechanism and the evaporator are provided, and the oil return mechanism is an oil pipe at the joint between the upstream pipe and the downstream pipe. An oil return pipe having one end opened to the flow inhibition wall, the oil sump, and the oil sump and the other end opened to the suction pipe, and the oil has been discharged from the compressor by the oil flow obstruction wall and has flowed in the pipe. The flow of refrigerating machine oil is obstructed and accumulated in the oil sump, whereby the oil is returned to the compressor through the oil return pipe.

Further, the oil return pipe and the expansion mechanism are arranged in a heat exchange manner.

[0013]

With the above construction, since the refrigeration cycle of the present invention connects the suction pipe from the compressor to the header from above, only the refrigerant vapor flows into the suction pipe and there is no liquid compression in the compressor. The life and reliability can be greatly improved.

Further, since the refrigerating machine oil is forcibly returned to the compressor through the oil returning pipe by the oil returning mechanism, there is no shortage of refrigerating machine oil in the compressor and the life and reliability of the compressor can be greatly improved.

Further, since the refrigerating machine oil is returned to the compressor on the upstream side of the evaporator, only the refrigerant flows in the evaporator, so that the heat exchange efficiency of the evaporator inner tube can be improved.

Further, by exchanging heat between the oil return pipe and the expansion mechanism, the temperature of the oil return pipe rises and the viscosity of the refrigerating machine oil flowing in the oil returning pipe can be lowered. It can facilitate the flow and ensure the return of refrigeration oil to the compressor.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS. 1 and 2, but the same components as those of the prior art will be designated by the same reference numerals and detailed description thereof will be omitted.

FIG. 1 is a refrigeration cycle diagram in the first embodiment of the present invention, and FIG. 2 is a sectional view of an oil return mechanism in the same embodiment.

A blower 9 is installed in the vicinity of the evaporator 4 and supplies air, which is heat-exchanged by the evaporator 4, to the evaporator 4. 18 is a header-, 10 is a header from the evaporator 4 outlet-
Reference numeral 11 denotes an evaporator outlet pipe inserted in the lower part of 18, and 11 is a suction pipe connecting the upper part of the header-18 and the compressor 1.

Reference numeral 12 denotes an oil return mechanism, one end of which is connected to the outlet of the expansion mechanism 3 and the other end of which is a throttle-shaped upstream pipe 13.
By inserting the downstream side pipe 14 connected to the inlet of the evaporator 4 into the
5, an oil sump 16 is formed between the oil flow obstruction wall 15 and the upstream pipe 13.

Reference numeral 17 denotes an oil return pipe having one end opened to the oil sump 16 and the other end opened to the suction pipe 11. Only the refrigerating machine oil 7 accumulated in the oil sump 16 is compressed by its own weight.
The inner diameter of the oil return pipe 17 is made smaller than the inner diameter of the evaporator 4 so that the refrigerant flows toward the evaporator 4.

Next, the operation will be described. At the outlet of the capillary tube of the expansion mechanism 3, the mixed flow of the refrigerant and the refrigerating machine oil 7 expands and expands, and the temperature decreases due to the decrease in the flow velocity and the evaporation of the refrigerant. As a result, the refrigerating machine oil 7 having no mutual solubility with the refrigerant such as HFC134a mainly composed of hydrofluorocarbon is reduced in the flow velocity and the viscosity is increased due to the temperature decrease, so that the inner wall of the upstream pipe 13 of the oil return mechanism 12 is increased. Will flow along.

The refrigerating machine oil 7 flowing along the inner wall is blocked in flow by the oil flow blocking wall 15 and is collected in the oil collecting portion 16. The accumulated refrigerating machine oil 7 is forcibly returned to the compressor 1 through the oil return pipe 17 and the suction pipe 11 by its own weight.

In the evaporator 4, since only the refrigerant flows through the oil return mechanism 12, the heat exchange efficiency on the inner wall of the evaporator 4 can be greatly improved. Further, in the header-18, since the suction pipe 11 piped from the compressor 1 is connected to the upper portion, only the vapor of the refrigerant can be returned to the compressor 1.

As described above, according to this embodiment, the compressor 1
A condenser 2, an expansion mechanism 3, an evaporator 4, a refrigerating cycle in which these are sequentially connected in a ring, a refrigerant containing hydrofluorocarbon as a main component, and no or little mutual solubility with the refrigerant. A refrigerator oil 7 and a suction pipe 11 which is a pipe from the compressor 1 are connected to an upper portion and a pipe 18 from the evaporator 4 is connected to a lower portion, and a header 18 is connected between the expansion mechanism 3 and the evaporator 4. The oil return mechanism 12 is provided.

Therefore, the oil return mechanism 12 has one end opened to the oil flow inhibiting wall 15, the oil sump 16 and the oil sump 16 at the joint between the upstream pipe 13 and the downstream pipe 14 and the other end to the suction pipe 11 The oil return pipe 17 opening to the oil flow blocking wall 15 blocks the flow of the refrigerating machine oil 7 discharged from the compressor 1 and flowing in the pipe by the oil flow obstructing wall 15, and the refrigerating machine oil 7 is accumulated in the oil sump portion 16 so that the oil is By returning to the compressor 1 via the return pipe 17, the suction pipe 1 from the compressor 1
Since 1 is connected to the header 18 from above, only the refrigerant vapor flows into the suction pipe 11 and there is no liquid compression in the compressor 1, and the life and reliability of the compressor 1 can be greatly improved.

Further, since the refrigerating machine oil 7 is forcibly returned to the compressor 1 via the oil returning pipe 17 by the oil returning mechanism 12, there is no shortage of the refrigerating machine oil 7 in the compressor 1 and the life and reliability of the compressor 1 are large. Can be improved.

Further, since the refrigerating machine oil 7 is returned to the compressor 1 on the upstream side of the evaporator 4, only the refrigerant flows in the evaporator 4, so that the heat exchange efficiency of the evaporator inner tube can be improved.

Next, a second embodiment of the present invention will be described with reference to FIG. 3. The same components as those of the conventional and the above-mentioned embodiments are designated by the same reference numerals and detailed description thereof will be omitted.

FIG. 3 is a refrigeration cycle diagram in the second embodiment of the present invention. Reference numeral 19 is an oil return pipe which is opened in the oil sump portion 16 at one end and opened at the other end in the suction pipe 11 and is arranged in heat exchange with the capillary tube of the expansion mechanism 3.

Next, the operation will be described. Oil return pipe 1
By exchanging heat with the capillary tube of the expansion mechanism 3, the temperature of the oil return pipe 19 rises, and the temperature of the refrigerating machine oil 7 flowing inside can be raised. Therefore, the viscosity of the refrigerating machine oil 7 decreases. The flow of the refrigeration oil 7 in the oil return pipe 19 can be promoted.

As described above, according to this embodiment, since the oil return pipe 19 and the expansion mechanism 3 are arranged in a heat exchange manner, the temperature of the oil return pipe 19 rises and the refrigerating machine oil flowing in the oil return pipe 19 is increased. The viscosity of 7 can be reduced, and the oil return pipe 1
The flow of the refrigerating machine oil in 9 can be promoted, and the refrigerating machine oil 7 can be surely returned to the compressor 1.

[0033]

As described above, the refrigeration cycle of the present invention is
A compressor, a condenser, an expansion mechanism, an evaporator, a refrigeration cycle in which these are sequentially connected in a ring, a refrigerant containing hydrofluorocarbon as a main component, and refrigeration having no or little mutual solubility with the refrigerant. Machine oil, a header having a suction pipe that is a pipe from the compressor connected to an upper portion and a pipe from the evaporator to a lower portion, and an oil return mechanism connected between the expansion mechanism and the evaporator, The oil return mechanism has an oil flow inhibiting wall, an oil return pipe having one end opened to the oil sump and the oil sump at the joint between the upstream side pipe and the downstream side pipe and the other end opened to the suction pipe, and the oil flow Since the flow of the refrigerating machine oil discharged from the compressor by the inhibition wall and flowing in the pipe is blocked and returned to the compressor via the oil return pipe by accumulating in the oil sump, the liquid refrigerant to the compressor No more inhalation, Liquid compression to be on a large problem-reliability can be prevented.

Further, since the refrigerating machine oil is forcibly returned to the compressor through the oil returning pipe by the oil returning mechanism, there is no shortage of refrigerating machine oil in the compressor, and abrasion due to insufficient lubrication of sliding parts in the compressor does not occur. It has a great effect on sex.

Further, since the refrigerating machine oil is returned to the compressor on the upstream side of the evaporator, only the refrigerant flows in the evaporator, so that the heat exchange efficiency of the evaporator inner tube can be greatly improved.

Furthermore, since the oil return pipe and the expansion mechanism are arranged in a heat exchange manner, the temperature of the oil return pipe rises and the viscosity of the refrigerating machine oil flowing in the oil return pipe can be lowered,
The flow of refrigerating machine oil in the oil return pipe can be promoted and the refrigerating machine oil can be reliably returned to the compressor.

[Brief description of drawings]

FIG. 1 is a piping diagram of a refrigeration cycle according to a first embodiment of the present invention.

FIG. 2 is a sectional view of the oil return mechanism of FIG.

FIG. 3 is a piping diagram of a refrigeration cycle according to a second embodiment of the present invention.

FIG. 4 is a piping diagram of a conventional refrigeration cycle diagram.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Compressor 2 Condenser 3 Expansion mechanism 4 Evaporator 7 Refrigerator oil 11 Suction piping 12 Oil return mechanism 13 Upstream side piping 14 Downstream side piping 15 Oil flow inhibition wall 16 Oil reservoir 17 Oil return piping 18 Header-19 Oil return piping

Claims (2)

[Claims] 1. A compressor, a condenser, an expansion mechanism, an evaporator, a refrigeration cycle in which these are sequentially connected in an annular shape, and a refrigerant containing hydrofluorocarbon as a main component.
Refrigerating machine oil having no or little mutual solubility with the refrigerant,
The oil return mechanism includes a header in which a suction pipe that is a pipe from the compressor is connected to an upper part and a pipe from the evaporator is connected to a lower part, and an oil return mechanism connected between the expansion mechanism and the evaporator. Has an oil flow inhibiting wall at the joint between the upstream pipe and the downstream pipe, an oil return pipe having one end open to the oil reservoir and the oil reservoir and the other end opening to the suction pipe. A refrigeration cycle characterized in that the flow of the refrigerating machine oil discharged from the compressor and flowing in the pipe is impeded and accumulated in the oil sump so as to be returned to the compressor via the oil return pipe. 2. The refrigeration cycle according to claim 2, wherein the oil return pipe and the expansion mechanism are arranged in a heat exchange manner.