JP2001021236A - Oil returning mechanism for refrigerating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oil returning mechanism to favorably return a refrigerator oil, accumulating in an accumulator and an evaporator, to a compressor. SOLUTION: This device comprises a floating body vertically moving so as to follow up a change in the height of a boundary 20 between a liquid refrigerant and refrigerator oil and situated at the bottom of a container into which a refrigerant and refrigerator oil for a refrigerating device using a refrigerant 19 having a specific gravity lower than the refrigerant oil 18 are introduced and which separately accumulated into upper and lower layers; an on-off valve 10 formed such that though usually closed, a gap between a valve element and a valve seat is opened as a result of the valve element being raised togetherwith the floating body when the height of a boundary exceeds a give value and closed when the height of the boundary is lowered to a value lower than a given height; and an oil return pipe 11 through which refrigerator oil from the on-off valve 10 is fed to the compressor or the suction pipe of the compressor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oil return mechanism for a refrigeration system, and more particularly to an oil return system for a vapor compression refrigeration system using a refrigerant having a specific gravity smaller than that of refrigeration oil.

[0002]

2. Description of the Related Art In a vapor compression type refrigerating apparatus, an accumulator for storing a liquid refrigerant that cannot be completely vaporized in an evaporator is provided in a suction pipe between the evaporator and the compressor. In this case, the compressor is prevented from being damaged by a so-called liquid bag generated by the liquid refrigerant flowing directly into the compressor.

An accumulator used conventionally has, for example, a structure as shown in FIG. 4, and the accumulator is provided in the middle of a suction pipe 30 between an evaporator and a compressor. The refrigerant from the evaporator is introduced into the can body 32 by the refrigerant inlet pipe 31, and the gas refrigerant in the refrigerant is removed by the refrigerant outlet pipe 33.
Is sent to the compressor through the suction pipe, and the liquid refrigerant 34 in the refrigerant is once accumulated in the can 32 and is vaporized in the can and then sent to the compressor.

A part of the liquid refrigerant 34 is supplied to a refrigerant outlet pipe 33.
Orifice 35 opened on the side of U-shaped bend pipe 33a
, Flows into the refrigerant outlet pipe 33, is vaporized by the suction pressure of the compressor, becomes gas refrigerant, and returns to the compressor.

[0005] By the way, the refrigerant contains refrigerating machine oil for lubricating the compressor. When the refrigerant is ammonia, the refrigerating machine oil is insoluble or hardly soluble in ammonia as the refrigerant, and the specific gravity of the refrigerating machine oil (0. 8 to 0.9) is greater than the specific gravity of the ammonia liquid (0.6 to 0.7), so that the refrigerating machine oil 34 is separated into two layers, a lower layer and a liquid refrigerant (ammonia liquid) 36, an upper layer. Collects in the can.

When the interface 37 between the refrigerating machine oil and the liquid refrigerant reaches the position of the orifice 35, the refrigerating machine oil flows from the orifice 35 into the refrigerant outlet pipe together with the refrigerant, and is carried by the flow of gas refrigerant sent to the compressor. Returned to

Therefore, the amount of the refrigerating machine oil returned to the compressor is determined by the diameter of the orifice 35. Since the refrigerating machine oil and the refrigerant have remarkably different viscosities, a desired amount of the refrigerating machine oil is returned to the compressor. It is difficult to set the orifice diameter.

That is, if the diameter of the orifice is increased, the amount of the refrigerant flowing into the refrigerant outlet pipe 33 is increased, and the refrigerant may return to the compressor as a liquid refrigerant and damage the compressor. If the diameter is reduced, the refrigerating machine oil becomes difficult to return to the compressor, and the compressor may be seized.

[0009] The above-mentioned problems are not limited to the refrigerating machine oil stored in the accumulator, but are also the same for the refrigerating machine oil stored in the plate-type or full-type evaporator.

[0010]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an oil return mechanism which can satisfactorily return refrigeration oil accumulated in an accumulator or an evaporator to a compressor.

[0011]

In order to achieve the above object, an oil return device according to the present invention is provided with a refrigerant of a refrigerating apparatus using a refrigerant having a specific gravity smaller than that of the refrigerating machine oil and a refrigerating machine oil. At the bottom of the container where the machine oil is separated and stored in two upper and lower layers, there is a floating body that moves up and down according to a change in the height of the interface between the liquid refrigerant and the refrigerating machine oil, and is usually closed. When the height of the interface exceeds a predetermined value, the valve body is raised together with the float and a gap between the valve body and the valve seat is opened, and when the interface height is equal to or less than the predetermined height, the valve is closed. And an oil return pipe for sending refrigeration oil from the on-off valve to the compressor or a suction pipe of the compressor.

The on-off valve includes a valve member provided with the float above a valve rod having a valve body, the valve member having an apparent specific gravity greater than the specific gravity of the liquid refrigerant, and It is assumed to be smaller than the specific gravity of the refrigerating machine oil.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an oil return mechanism according to the present invention will be described below in detail with reference to specific examples shown in FIGS. In this embodiment, a specific example in which an oil return mechanism is provided in an accumulator will be described.

The accumulator 1 has a can body 2 serving as a container for storing a liquid refrigerant, and a refrigerant inlet pipe 6 and an outlet pipe whose outer ends are connected in the middle of a suction pipe 5 between an evaporator 3 and a compressor 4 of a refrigeration system. 7, the respective inner ends of the refrigerant inlet pipe 6 and the outlet pipe 7 penetrate through the top wall of the can body 2 and are introduced into the can body. The refrigerant inlet pipe 6 opens downward in the can body 2, The outlet pipe 7 has a U-shaped bend pipe 7b following the vertical pipe 7a,
An end of the bend tube portion is open upward, and an orifice 8 is opened at the bottom side surface of the bend tube portion 7b.

An oil return mechanism 9 according to the present invention is provided at the bottom of the can body 2. The oil return mechanism is normally closed. And an oil return pipe 11 having one end connected to the open / close valve and the other end connected in the middle of a compressor or a suction pipe of the compressor. I have.

As shown in FIG. 2, for example, the on-off valve 10 includes a float 12, a valve rod 13 having an upper end fixed to a lower portion of the float, and a valve 14 attached to the valve rod. And a valve seat 16 for receiving the valve element 14 and a guide 17 for supporting the valve rod 13 slidably up and down. The valve rod 13 is formed at the lower end thereof. Is prevented by the enlarged diameter portion 13a.

The float 12 is made of a thin hollow sphere made of, for example, iron or stainless steel, and the apparent specific gravity of the entire valve member 15 is between the specific gravities of the refrigerating machine oil 18 and the liquid refrigerant (ammonia liquid) 19. The valve member 15 is vertically displaced in accordance with the vertical change of the interface 20 between the refrigerating machine oil and the liquid refrigerant.

Specifically, the specific gravity of the refrigerating machine oil 18 is 0.8
Since the specific gravity of the ammonia liquid as the liquid refrigerant 19 is 0.6 to 0.7, the specific gravity of the entire valve member 15 is set to 0.7 to 0.8.

The on-off valve 10 is connected to the refrigerating machine oil 1.
The vertical spacing between the float 12 and the valve 14 is set so that the interface 20 between the liquid 8 and the liquid refrigerant 19 is opened at a position lower than the orifice 8, and the refrigerating machine oil 18 flows from the orifice 8 into the refrigerant outlet pipe 7. Avoid inflow.

Next, the operation of the accumulator 1 having the oil return mechanism 9 configured as described above will be described. Refrigerant that has passed from the compressor 4 through the condenser 21, the expansion valve 22, and the evaporator 3 enters the can body 2 of the accumulator 1 from the refrigerant inlet pipe 6, and gas refrigerant enters the outlet pipe from the open end of the refrigerant outlet pipe 7. Is returned to the compressor 4 by the suction pipe 5.

The liquid refrigerant and the refrigerating machine oil in the refrigerant accumulate in the can body 2. The liquid refrigerant 19 and the refrigerating machine oil 18 are divided into two layers in which the liquid refrigerant 19 is an upper layer and the refrigerating machine oil 18 is a lower layer due to a difference in specific gravity. Separated and accumulated.

When the liquid refrigerant and the refrigerating machine oil accumulate, the upper layer liquid refrigerant 19 flows into the refrigerant outlet pipe 7 from the orifice 8 of the refrigerant outlet pipe 7, and is vaporized by the suction pressure of the compressor to become a gas refrigerant, and is compressed. Returned to machine 4.

When the refrigerating machine oil 18 accumulates in the can 2, the interface 20 between the refrigerating machine oil 18 and the liquid refrigerant 19 rises, the valve member 15 of the on-off valve 10 also rises, and the valve body 14 and the valve seat 16 A refrigeration oil 18 accumulated in the lower layer of the can body flows into the oil return pipe 11 from this gap, and is sent to the middle of the suction pipe 5 of the compressor 4, along with the gas refrigerant flowing in the suction pipe. It is returned to the compressor 4.

When the refrigerating machine oil 18 flows out of the oil return pipe 11, the interface 20 is lowered, so that the valve member 15 of the on-off valve 10 is also lowered together with the interface 20, and the valve body 14 and the valve seat 1 are moved.
The gap between the cylinders 6 is closed and the refrigerating machine oil does not flow out.

In the above embodiment, the outlet end of the oil return pipe is connected to the middle of the suction pipe of the compressor. However, the oil return pipe may be connected to the oil supply port of the compressor.

In the above-described embodiment, the accumulator provided with the oil return mechanism has been described. However, the oil return mechanism of the present invention may be applied to the bottom of the container of a plate type or full type evaporator. It may be applied to

[0027]

According to the oil return mechanism of the present invention, the refrigerating machine oil contained in the refrigerant can be reliably separated from the liquid refrigerant, and the separated refrigerating machine oil can be satisfactorily returned to the compressor. Seizure can be prevented.

Further, since the liquid refrigerant can be reliably separated, the liquid back can be reliably prevented in the accumulator provided with the oil return mechanism of the present invention, and the compressor can be prevented from being damaged by the liquid back.

Further, the oil return mechanism of the present invention has a simple structure using an on-off valve which is opened and closed by a float, and has the advantages that maintenance is easy and the cost of the apparatus can be reduced.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of an accumulator provided with an oil return mechanism according to the present invention.

FIG. 2 is an enlarged vertical sectional view of an oil return mechanism.

FIG. 3 is a configuration diagram showing an example of a refrigeration apparatus including the accumulator of FIG.

FIG. 4 is a longitudinal sectional view showing an example of a conventional accumulator.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Accumulator 2 Can body 3 Evaporator 4 Compressor 5 Suction pipe 6 Refrigerant inlet pipe 7 Refrigerant outlet pipe 8 Orifice 9 Oil return mechanism 10 Open / close valve 11 Oil return pipe 12 Floating body 13 Valve rod 14 Valve body 15 Valve member 16 Valve seat 17 Guide 18 Refrigeration oil 19 Liquid refrigerant 20 Interface 21 Condenser 22 Expansion valve

Claims (2)

[Claims] A refrigerant having a specific gravity lower than that of the refrigerating machine oil is introduced into the refrigerating machine and the refrigerating machine oil is introduced into the refrigerating machine oil. It has a float that moves up and down following a change in the height of the interface between the refrigerant and the refrigerating machine oil, and is normally closed, but when the height of the interface exceeds a predetermined value, a valve is placed together with the float. The body is raised to open a gap between the valve body and the valve seat, and the on-off valve is closed when the interface height is equal to or less than the predetermined height.The compressor oil is compressed by the compressor or the compressor. Oil return mechanism for a refrigeration system that has an oil return pipe that feeds to the suction pipe of the machine. 2. The on-off valve according to claim 1, further comprising a valve member provided with the float above a valve rod having a valve body, wherein the apparent specific gravity of the valve member is greater than the specific gravity of the liquid refrigerant, and The oil return mechanism of the refrigeration system according to claim 1, wherein the specific gravity is smaller than the specific gravity of the refrigeration oil.