JPH03168565A - Refrigeration cycle - Google Patents

Abstract

PURPOSE:To eliminate a lack of oil of a refrigerant compressor even in case of high speed operation of the refrigerant compressor by a method wherein a bypassing circuit is provided with a differential pressure valve to be opened when a pressure at a refrigerant evaporator is higher than a pressure at the refrigerant compressor by a predetermined value. CONSTITUTION:When a cooling compressor 2 is operated at a high speed, a differential pressure between a refrigerant evaporator 6 and a refrigerant compressor 2 is increased as its suction force is increased. As the differential pressure is more than a predetermined pressure of about 1kg/cm<2> a differential pressure valve 8 is opened. As a result, liquid refrigerant containing oil is flowed out of the bottom part of the refrigerant evaporator 6, the refrigerant may pass through an accumulator 15 and a bypassing pipe 16 and then the refrigerant is sucked into the refrigerant compressor 2. In this way, in the cycle 1, the refrigerant compressor 2 is operated at a high speed when the pressure adjusting valve 7 is operated, and in case that a lack of oil may easily occur, the liquid refrigerant containing oil is returned back from the bypassing passage 16 to the refrigerant compressor 2, resulting in that the lack of oil can be eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a refrigeration cycle in which a pressure regulating valve is provided between a refrigerant evaporator and a refrigerant FF compressor.

``Tsong Song Technology 1 Conventionally, in the refrigeration cycle used in air-conditioning equipment, there is a ``power adjustment valve'' between the refrigerant evaporator and the refrigerant E'Elii machine, and the refrigerant returns from the refrigerant evaporator to the refrigerant compressor I\. The amount is set to A and the evaporation pressure in the refrigerant fish generator is set to a constant value (approximately 1.9 kg/
cJ) or more, the frost of the refrigerant evaporator at low loads can be reduced to 1[. A method (EPR method) is known.

The pressure regulating valve includes a diaphragm on which the evaporation pressure of the refrigerant acts, and a slide valve interlocked with the diaphragm, and the slide valve opens a refrigerant passage to adjust the flow rate of the refrigerant.

The diaphragm is pushed with a predetermined force by a spring.
As the evaporation pressure changes, the spring force will be displaced to a position where the evaporation pressure is balanced.

For example, when the cooling load decreases and the evaporation pressure of the refrigerant decreases, and the pressing force of the spring becomes greater than the evaporation pressure, the slide valve moves in the direction of closing the refrigerant passage, reducing the cooling flJt, and as a result, Keep evaporation pressure at set point.

Conversely, when the cooling load increases and the evaporation pressure of the refrigerant reaches its upper limit, and the evaporation pressure of the refrigerant becomes greater than the pressing force of the spring, the slide valve opens fully, and the refrigerant evaporated in the refrigerant evaporator remains as it is. The refrigerant is sucked into the compressor.

[Problem to be solved by the invention] However, when the refrigerant compressor is operated at high speed during low load, as the evaporation pressure in the refrigerant evaporator decreases, the refrigerant passage is closed by the pressure regulating valve. The squeeze area becomes larger.

Therefore, since the amount of refrigerant that returns from the refrigerant evaporator to the refrigerant compressor decreases, the amount of flowing oil contained in the refrigerant (lubricating oil for the refrigerant compressor) also decreases, causing seizure on each sliding part of the refrigerant compressor. could have occurred.

The present invention has been made based on the above circumstances, and an object of the present invention is to provide a refrigeration system that can eliminate oil shortage in a refrigerant compressor even when the refrigerant compressor is operated at high speed when the pressure regulating valve is activated. The goal is to provide a cycle.

1,000 Steps to Solve the Problems 1 In order to achieve the above object, the present invention includes adjusting the amount of refrigerant that returns from the refrigerant evaporator to the refrigerant compressor between a refrigerant evaporator and a refrigerant compressor. In a refrigeration cycle equipped with a single pressure valve that maintains the evaporation pressure in the refrigerant evaporator at a certain value or higher, the pressure adjustment valve is bypassed and the pressure adjustment is performed in a region where oil tends to accumulate in the refrigerant evaporator. A bypass passage connecting the downstream side of the valve is provided, and a differential pressure valve that opens when the pressure on the refrigerant evaporator side is higher than the pressure on the refrigerant compressor side by a predetermined value or more is provided in the bypass passage. Use technical means.

1. The refrigeration cycle of the present invention having the above structure has the following functions.

When the cooling load is large and the evaporation pressure in the refrigerant evaporator is above a certain value, the pressure regulating valve will not operate, and
Difference: Since the valve is also closed, the refrigerant evaporated in the refrigerant evaporator is directly sucked into the refrigerant compressor.

When the cooling load is small and the evaporation pressure in the refrigerant evaporator is low and the pressure regulating valve is activated (the refrigerant passage is throttled), the air passes through the pressure A eagle valve to keep the evaporation pressure above a certain value. The amount of refrigerant is running low.

Along with the operation of the pressure regulating valve, a pressure difference is generated between the refrigerant evaporator 11pl and the refrigerant compression side of the differential valve depending on the operating state of the refrigerant compressor.

At this time, when the differential pressure between the refrigerant evaporator side and the refrigerant ff compression v1lItlI is less than a predetermined value (for example, I K (1/cJ)), the differential valve is closed.

When the refrigerant compressor is operated at high speed, the refrigerant evaporator side and the refrigerant
When the differential pressure with the compressor side increases and the differential pressure reaches a predetermined one or more, the differential pressure valve opens. As a result, the liquid refrigerant containing the oil (refrigerant ff1i!i) flows out from the bottom of the refrigerant evaporator and is sucked into the refrigerant compressor through the bypass passage.

[Effects of the Invention] According to the present invention having the above-mentioned effects, by providing a differential valve in the bypass passage that bypasses the pressure regulating valve, the opening of the differential pressure valve allows liquid refrigerant that has evaporated oil. can be returned to the refrigerant compressor through the bypass passage.

Therefore, if the refrigerant pressure WI machine is operated at high speed when the pressure regulating valve is activated, even if the amount of oil passing through the pressure regulating valve decreases, the differential pressure valve will open and the oil-rich liquid refrigerant will be transferred to the refrigerant. Since it is sucked into the E-compressor, it is possible to eliminate oil shortages that occur in the past.

L Embodiment Next, the refrigeration cycle of the present invention will be explained based on an embodiment not shown in the drawings.

FIG. 1 shows a schematic diagram of the refrigeration cycle.

The refrigeration cycle 1 consists of a refrigerant, a compressor 2, a refrigerant condenser 3, a receiver 4, and an expansion valve (external pressure equalization type expansion valve).
A pressure regulating valve 7 is provided between the refrigerant evaporator 6 and the refrigerant compressor 2 for the froth I to II side 11 of the refrigerant evaporator 6. is provided.

In addition, the refrigeration cycle 1 of this embodiment is provided with a bypass passage (described later) that bypasses the pressure regulation valve 7 and connects the bottom of the refrigerant evaporator 6 and the downstream side of the pressure regulation valve 7. A refrigerant evaporator 6 1T is installed in the bypass passage.
[Differential pressure valve 8 that opens when the pressure of lI is higher than the pressure on the compressor 2 side of the refrigerant by more than a predetermined value (IKq/aJ in this embodiment)
is installed.

The refrigerant evaporator 6 includes a flat tube 9 as shown in FIG.
and a large number of corrugated fins 10 f? It is a single-tank type in which the refrigerant tank 11 is formed only in the upper part of each flat tube 9.

Since the box-type expansion valve 5 is assembled to the refrigerant evaporator 6, an inlet pipe 12 is installed in the center of the refrigerant tank 11.
and an outlet pipe 13 are attached.

Further, a specific tube 9a of the refrigerant evaporator 6 has a connecting pipe 1 that communicates with a refrigerant flow path formed in the tube 9a.
4 is formed. This connecting pipe 14 connects oil (refrigerant compressor 2
This is a diagonal outlet for taking out the refrigerant containing the lubricating fluid. Therefore, the connecting pipe 14 is installed in the refrigerant evaporator 6 at a place where oil accumulates or in the groove, and is installed in the first flow of the refrigerant flow path as much as possible in order to suppress a decrease in the performance of the refrigerant evaporator G due to taking out the refrigerant. There is a need.

Therefore, in the refrigerant evaporator 6 of this example, the refrigerant tank 11
A specific chico placed on the exit pipe 13 side from the center of
It is shaped at the lower end of the tube 9a. As shown in FIG. 3, the connecting pipe 14 is provided with protrusions 14a each having a semi-elliptical cross-sectional shape at the lower ends of two circular plates 9b that connect the tube 9a. It is formed by joining two molded plates 9b facing each other.

As shown in FIG. 2, an accumulator 15 forming a part of the bypass passage is assembled to this connecting vibe 14, and is integrally brazed to the refrigerant evaporator 6 in the furnace. Note that a predetermined amount of oil is stored inside the accumulator 15, and an outlet pipe (not shown) of the accumulator 15 is taken out from the oil. Therefore,
The refrigerant containing oil from the refrigerant evaporator 6 is transferred to the connecting pipe 1.
4 into the accumulator 15, the oil stored in the accumulator 15 will flow out via the outlet pipe.

The outlet piping of the accumulator 15 has a union half
(not shown) to which the differential pressure valve 8 is connected, and furthermore, the differential pressure valve 8 and the downstream side of the pressure regulating valve 7 form a bypass passage together with the axmulator 15 through a bypass pipe 16.
connected by.

The pressure regulating valve 7 adjusts the amount of refrigerant returned from the refrigerant evaporator 6 to the refrigerant compressor 2, and keeps the evaporation pressure of the refrigerant in the refrigerant evaporator 6 to a constant value (approximately 1.9 K (1/a { ) or more). As shown in FIG.
It is connected to the refrigerant pipe 18. In addition, a bypass pipe 1 is connected to the hose block 17 via a block plate 19.
6 is connected.

The pressure regulating valve 7 includes a diaphragm (not shown) on which the evaporation pressure of the refrigerant in the refrigerant evaporator 6 acts, and a slide valve (not shown) interlocked with the diaphragm, and the slide valve opens and closes the refrigerant passage. By doing so,
This is to adjust the refrigerant flow trench.

The diaphragm is pressed with a predetermined force by a spring (not shown), and is displaced in response to changes in evaporation pressure to a position where the spring force and evaporation pressure are balanced.

For example, when the cooling load decreases and the evaporation pressure of the refrigerant becomes low, and the pushing force of the spring becomes greater than the evaporation pressure, the slide valve moves in the direction of closing the refrigerant passage, reducing the amount of refrigerant. As a result, the evaporation pressure is maintained at the set value.

Conversely, when the cooling load increases and the refrigerant pressure increases, and the evaporation pressure of the refrigerant becomes greater than the pressing force of the spring, the total number of slide valves becomes 114, and the refrigerant evaporated in the refrigerant evaporator 6 remains as it is. Refrigerant/[a! Sucked into 2.

Next, the operation of the tree loss embodiment will be explained.

b) When the cooling load is large and the power of the refrigerant generator 6 is higher than the fixed value.

Since the evaporation pressure is greater than the spring force of the pressure regulating valve 7, the pressure regulating valve 7 does not operate. In other words, since the slide valve is fully open, the amount of oil sucked into the refrigerant compressor 2 together with the refrigerant is large, and there is no shortage of oil in the refrigerant compression Ja2. In this case, the differential pressure valve 8 is closed because no differential pressure is generated between the refrigerant generator 6 +tlll and the refrigerant compressor fi2 {1111.

(Example) When the cooling load is small and the evaporation pressure in the refrigerant evaporator 6 becomes smaller than the spring force of the pressure regulating valve 7.

The slide valve narrows the refrigerant passage in conjunction with the diaphragm pressed by the spring, and the refrigerant evaporator 6
Keep the evaporation pressure at or above a certain value.

At this time, if the refrigerant compressor 2 is operated at low speed and the suction force is small, the differential pressure between the refrigerant evaporator 6 side and the refrigerant compressor 2 open is I
It becomes less than K(]/1, and the differential valve 8 is closed.

Therefore, when the refrigerant compressor 2 is operated at high speed, the refrigerant "f5
Since the suction force of the refrigerant evaporator 2 increases and the evaporation pressure in the refrigerant evaporator 6 further decreases, the amount of throttle of the slide valve increases. As a result, the refrigerant pressure from the refrigerant evaporator 6 is 11!11
As the refrigerant 1L decreases, the amount of oil that passes through the pressure A regulating valve 7 and is sucked into the refrigerant compressor 2 also decreases.

However, in this case, as the suction force of the refrigerant compressor 2 increases, the refrigerant evaporator 6 side and the refrigerant compressor 1? '12 f
l. The differential pressure between IllI and IllI increases, and that differential pressure becomes IK
By being north of g/(-, the differential pressure valve 8 opens.

As a result, liquid refrigerant containing oil flows out from the bottom of the refrigerant generator 6, causing the accumulator 15 and the bypass pipe 16 to flow out.
The refrigerant is sucked into the refrigerant compressor 2.

As described above, in the refrigeration cycle 1 of this embodiment, when the pressure regulating valve 7 is operated (during low load), the refrigerant ffW+i
Even if the refrigerant 82 is operated at high speed and is likely to run out of oil, the opening of the differential valve 8 allows the oil-containing liquid refrigerant to flow through the bypass passage (accumulator 15 and bypass pipe 1).
6), the refrigerant can be returned to the refrigerant compressor 2, which eliminates the problem of oil shortage that occurs in the prior art.

(Modification) In the above embodiment, the accumulator 15 is attached to the connection pipe 14 of the refrigerant evaporator 6, but it is possible to obtain the effects of the present invention without providing the accumulator 15. That is, since the differential valve 8 is opened during low load, the refrigerant flowing out from the refrigerant evaporator 36 becomes almost liquid phase refrigerant. Therefore, it is not necessarily necessary to provide the accumulator 15.

Although the difference "difference when valve 8 opens" is defined as IK(]/cJ or J, it is not limited to this value.

[Brief explanation of the drawing]

1 to 4 show an embodiment of the present invention,
Fig. 1 is a schematic diagram of the refrigeration cycle, Fig. 2 is a perspective view of the refrigerant evaporator with an axmulator and differential pressure valve assembled, Fig. 3 is a plan view of the flat tube on which the connecting vibe is formed, and Fig. 4 is It is a figure showing the connection state of a pressure regulation valve, a bypass pipe, and a refrigerant piping. In the diagram: 1... Refrigeration cycle 2... Refrigerant compressor 6... Refrigerant evaporator 7... Pressure adjustment valve 8... Difference valve 1h... Accumulator (bypass passage) 16. Bypass pipe (bypass passage) )

Claims (1)

[Claims] 1) Between a refrigerant evaporator and a refrigerant compressor, the evaporation pressure in the refrigerant evaporator is kept at a constant value by adjusting the amount of refrigerant that returns from the refrigerant evaporator to the refrigerant compressor. In a refrigeration cycle provided with a pressure regulating valve that maintains the pressure above, a bypass passage is provided that bypasses the pressure regulating valve and connects a region in the refrigerant evaporator where oil tends to accumulate and a downstream side of the pressure regulating valve; A refrigeration cycle characterized in that the bypass passage is provided with a differential pressure valve that opens when the pressure on the refrigerant evaporator side is higher than the pressure on the refrigerant compressor side by a predetermined value or more.