JP3291424B2 - Air conditioner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner having a variable capacity compressor and a fixed capacity compressor connected in parallel with each other.

[0002]

2. Description of the Related Art In general, an air conditioner is known in which a variable capacity compressor and a fixed capacity compressor are connected in parallel, and an oil separator is provided in a refrigerant pipe on the discharge side of the compressor (Japanese Patent Laid-Open No. Hei 2 (1994)). No.-123053). This type of air conditioner is equipped with a variable capacity compressor and a fixed capacity compressor, so it is easy to respond to fluctuations in cooling and heating loads, and depending on the size of the cooling and heating loads, the operation of either compressor is Since it can be stopped, there is an advantage that energy can be saved and it is economical.

[0003]

However, in the conventional air conditioner described above, in order to return the lubricating oil from the oil separator almost equally to the two compressors, an oil return pipe from the oil separator is provided. It must be connected to the suction pipe of each compressor. This causes a problem that the number of oil return pipes increases.

[0004] In this type of compressor parallel refrigeration cycle, in addition to operating two compressors together, often only one of them is operated.

[0005] When only one of the compressors is operated, lubricating oil only needs to be returned to the compressor to be operated. Conventionally, both lubricating oils have to be returned regardless of the operation state. Oil is returned from the oil return pipe to the compressor, and from that point, a reasonable supply of lubricating oil has been an issue.

Accordingly, an object of the present invention is to solve the problems of the prior art, reduce the number of pipes, and ensure that each compressor does not run out of oil in accordance with the operation mode of the parallel type compressor. Another object of the present invention is to provide an air conditioner improved so that lubricating oil can be rationally supplied from an oil separator.

[0007]

According to a first aspect of the present invention, a plurality of compressors are connected in parallel, and one compressor is connected to a refrigerant pipe joined on the discharge side of each compressor. An oil separator is provided, and an oil return pipe led out of the oil separator is connected to the suction pipe of one compressor that always operates, and the overflow pipe for lubricating oil from this one compressor is operated when the load increases. Connected to the suction pipe of the other compressor and the overflow pipe.
Lubricating oil is used when the other compressor is stopped.
It is characterized in that it is configured to be returned to the compressor .

According to a second aspect of the present invention, a variable capacity compressor and a fixed capacity compressor are connected in parallel, and one refrigerant separator is provided in a refrigerant pipe joined on the discharge side of each compressor. with connecting oil return pipe derived from the separator to the suction pipe of the variable capacity type compressor, connect the overflow pipe of the lubricating oil from the variable capacity type compressor to the suction tube of capacity fixed type compressor, this over Flow
-Lubricating oil flowing through the pipes is
In this case, the compressor is configured to be returned to the variable capacity compressor .

According to these inventions, the lubricating oil from the oil separator is supplied directly from the oil return pipe or the suction pipe of one of the compressors (variable capacity type compressor) to the one of the currently operating compressor (capacity). (Variable compressor). Also, if the other compressor (constant capacity compressor) has stopped operating,
Since the pressure is higher than the low pressure side of one of the operating compressors (variable capacity type compressor), the lubricating oil flowing through the overflow pipe tends to flow to the low pressure side. A sufficient amount of oil can be maintained without being affected by the (fixed capacity compressor). When both compressors are operating together, the oil separated from the refrigerant by the oil separator first flows through the oil return pipe toward the low pressure side, and one of the compressors (variable capacity compression ) Is sucked into one of the compressors (variable capacity compressor). When the amount of oil is sufficient, the surplus lubricating oil flows through the overflow pipe and flows into the other compressor (constant capacity compressor), so that the other compressor (constant capacity compressor) Oil balance can be ensured so that lubricating oil does not run short.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an air conditioner according to the present invention will be described below with reference to the accompanying drawings.

In FIG. 1, reference numeral 10 denotes an outdoor unit, and reference numeral 12 denotes an indoor unit. Outdoor unit 1
0 is an accumulator 13 and a variable capacity compressor 1
4, a fixed capacity compressor 15 and an oil separator 1
6, the four-way valve 17, the outdoor heat exchanger 18, and the outdoor electric expansion valve 19 are sequentially connected by refrigerant piping.
The indoor unit 12 includes an indoor heat exchanger 40 and an indoor electric expansion valve (hereinafter, referred to as an indoor mechanical valve 41). In this embodiment, this indoor unit 12
A plurality of units are connected in parallel by unit-to-unit piping composed of a gas pipe 42 and a liquid pipe 44. The variable capacity compressor 14 and the fixed capacity compressor 15 are connected in parallel, and the three-way joint 2 is connected downstream of the accumulator 13.
The suction pipes 21a and 21b of the variable capacity compressor 14 and the fixed capacity compressor 15 are diverged through 0.

The variable capacity compressor 14 can control the discharge amount of the refrigerant by using the pressure of the lubricating oil separated by the oil separator 16.

The structure of the variable capacity compressor 14 will be briefly described. The outlet side of the oil separator 16 and the suction pipe 21a of the variable capacity compressor 14 are connected via a high pressure oil pipe 24. The oil pipe 24 is provided with a high-pressure control valve 25 and a low-pressure control valve 26 downstream thereof.
From between the high pressure control valve 25 and the low pressure control valve 26, a pipe 2
7, and the pipe 27 is connected to the variable capacity compressor 14.
Is supplied to the control port 14a, whereby oil is supplied to the control port 14a.

By switching between the high pressure control valve 25 and the low pressure control valve 26, the control port 14
The pressure of the oil flowing to a can be adjusted. That is, when the high-pressure control valve 25 is open and the low-pressure control valve 26 is closed, high-pressure oil is sent to the control port 14a, the high-pressure control valve 25 is closed, and the low-pressure control valve 26 is opened. Is low, pressure is applied to the control port 14a.

According to this embodiment, when high-pressure oil is sent to the above-described control port 14a, a valve (not shown) built in the variable capacity compressor 14 is closed, and the variable capacity type compressor 14 is closed. The compressor 14 is operated at full power horsepower. When a low pressure is applied to the control port 14a, a valve (not shown) built in the variable capacity compressor 14 is opened, and the variable capacity compressor 14 is fully operated. Driven at half the power of the power.

On the other hand, the respective discharge pipes 22a and 22b of the variable capacity compressor 14 and the fixed capacity compressor 15 are connected to the inlet side of an oil separator 16 which separates the lubricating oil from the discharged refrigerant after being joined. And the separated lubricating oil is discharged from the two outlets of the oil separator 16.
The oil is returned to the variable capacity compressor 14 and the fixed capacity compressor 15 through an oil return pipe 23 drawn from one side.

According to this embodiment, the oil return pipe 2
The third pipe end 23a is directly connected to the suction pipe 21a of the variable capacity compressor 14 among the suction pipes 21a and 21b of the variable capacity compressor 14 and the fixed capacity compressor 15 respectively.

The variable capacity compressor 14 is connected to an overflow pipe 28 which connects the suction pipe 21b of the capacity one type compressor 15, and when the lubricating oil of the variable capacity compressor 14 exceeds a predetermined amount, excess oil is removed. It can be led out to the fixed compressor 15. The overflow pipe 28 incorporates a strainer 29 and a throttle 30 for reducing oil pressure. In addition, an overflow pipe 31 that connects the suction pipe 21a of the variable capacity compressor 14 is connected to the fixed capacity compressor 15, and the overflow pipe 31 is provided with a strainer 32 and a throttle 33 for depressurizing oil. Have been.

Reference numeral 34 denotes a bypass pipe for guiding the high-pressure refrigerant discharged from the compressor to the accumulator 13 without circulating through the refrigeration cycle.
4, an on-off valve 100 and a capillary tube 101 are connected. When the on-off valve 100 is opened, a part of the refrigerant is guided to the accumulator 13 without circulating in the refrigeration cycle, whereby the discharge amount of the compressor is reduced by one horsepower. Reference numeral 35 denotes an on-off valve for stopping the flow of the refrigerant in the gas pipe 42, and reference numeral 36 denotes an on-off valve for stopping the flow of the refrigerant in the liquid pipe 44.

Next, the operation will be described. In the case of the cooling operation, when the four-way valve 17 switches as shown in FIG. 1, the refrigerant flows as shown by the arrow. In this case, in the outdoor unit 10, the outdoor electromagnetic expansion valve 19 is substantially fully opened, and the opening of the indoor mechanical valve 41 is adjusted according to the load. Outdoor heat exchanger 1
8 functions as a condenser, the indoor heat exchanger 40 functions as an evaporator, and cool air is sent from the indoor heat exchanger 40 to perform a cooling operation.

On the other hand, when the four-way valve 17 is switched in the opposite direction to that in FIG. 1, the refrigerant flows in the direction of the dotted line in FIG. In this case, the opening degree of the outdoor electromagnetic expansion valve 19 and the indoor mechanical valve 41 is adjusted according to the load. The outdoor heat exchanger 18 functions as an evaporator, the indoor heat exchanger 40 functions as a condenser, and warm air is blown from the indoor heat exchanger 40 to perform a heating operation.

In such a cooling and heating operation, of the two compressors, normally, the variable capacity compressor 14 is always operated, and when the load increases, the fixed capacity compressor 15 is also operated at the same time. In the compressor, the lubricating oil is discharged together with the refrigerant, and the amount of the oil gradually decreases. According to the present embodiment, as described below, the variable capacity compressor 1
4. The constant-capacity compressor 15 is supplied with lubricating oil separated by an oil separator so that the amount of oil does not run short during operation.

FIG. 2 is a diagram showing the flow of oil separated by the oil separator 16 when the variable capacity compressor 14 is operated and the fixed capacity compressor 15 is stopped. In this case, during the operation of the variable capacity compressor 14, the high-pressure control valve 25 and the low-pressure control valve 26 are opened and closed according to the cooling / heating load, as described above, to control the discharge flow rate.

The lubricating oil separated from the refrigerant by the oil separator 16 flows through the oil return pipe 23 toward the low pressure side, and flows directly from the suction pipe 21a into the currently operating variable capacity compressor 14 which is currently operating. Further, since the operation of the constant capacity compressor 15 is stopped, the pressure thereof becomes higher than the low pressure side of the operating compressor. Therefore, since the lubricating oil flowing through the overflow pipe 28 easily flows to the low pressure side, as shown by the arrow in FIG. Is supplied to the mold compressor 14. In this way, since all the separated lubricating oil flows into the variable capacity compressor 14 during operation, a sufficient amount of oil is maintained without being affected by the constant capacity compressor 15 during stoppage. be able to.

FIG. 3 is a diagram showing the flow of lubricating oil when both the variable capacity compressor 14 and the fixed capacity compressor 15 are operating. In this case, the oil separated from the refrigerant by the oil separator 16 first flows through the oil return pipe 23 toward the low pressure side, flows into the suction pipe 21a, and flows from the suction pipe 21a to the variable capacity compressor 14. Sucked into. When the variable-capacity compressor 14 has a sufficient amount of oil, excess lubricating oil flows through the overflow pipe 28 and flows into the constant-capacity compressor 15 as indicated by the arrow in the figure. Therefore, it is possible to balance oil so that lubricating oil does not run short during the operation of the fixed capacity compressor 15.

According to this embodiment, the oil return pipe 2
3 is connected to a suction pipe 21a extending in the vertical direction. According to this, even if the variable capacity type compressor 14 stops and the fixed capacity type compressor 15 operates, the lubricating oil returning to the suction pipe 21a is not directly below (the three-way joint 2).
After flowing down in the direction of 0) and flowing down the three-way joint 20, the suction pressure of the fixed capacity compressor 15 causes the oil to be drawn upward, so that the lubricating oil does not accumulate in the accumulator 13.

As described above, the present invention has been described with reference to the preferred embodiments. However, in the present invention, the same effect can be obtained even if the control of the variable capacity compressor is performed by frequency control using an inverter.

[0028]

As is apparent from the above description, according to the present invention, while the compressors connected in parallel are operating together, or even when only one of them is operating, both are separated from the oil separator. Since the lubricating oil can be supplied to the operating compressor through the oil return pipe, the oil amount can be ensured so that the compressor does not run out of oil. Further, the number of oil return pipes can be reduced as compared with the related art.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a refrigeration cycle of an embodiment of an air conditioner according to the present invention.

FIG. 2 is a circuit diagram showing a flow of lubricating oil when the variable capacity compressor is operated and the fixed capacity compressor is stopped in the refrigeration cycle of FIG. 1;

FIG. 3 is a circuit diagram showing a flow of lubricating oil when both a variable capacity compressor and a constant capacity compressor are operated in the refrigeration cycle of FIG. 1;

[Explanation of symbols]

 Reference Signs List 10 outdoor unit 12 indoor unit 13 accumulator 14 variable capacity compressor 15 constant capacity compressor 16 oil separator 17 four-way valve 18 outdoor heat exchanger 19 outdoor expansion valves 21a, b suction pipes 22a, b discharge pipe 23 oil return pipe 28 Overflow pipe 40 Indoor heat exchanger 41 Indoor expansion valve 42 Gas pipe 44 Liquid pipe

Claims (2)

(57) [Claims] 1. A compressor in which a plurality of compressors are connected in parallel, one refrigerant separator is provided in a refrigerant pipe joined on the discharge side of each compressor, and an oil return pipe derived from the oil separator is always operated. And the overflow pipe for lubricating oil from one compressor is connected to the suction pipe of the other compressor that operates when the load increases, and the lubricating oil flowing through this overflow pipe is connected to the other pipe.
If one compressor is stopped, it is returned to the other compressor
An air conditioner characterized by having a configuration as described above . 2. A variable capacity compressor and a fixed capacity compressor are connected in parallel, and one refrigerant separator is provided in a refrigerant pipe joined on the discharge side of each compressor, and an oil return pipe derived from the oil separator is provided. Is connected to the suction pipe of the variable capacity compressor, and the overflow pipe of the lubricating oil from the variable capacity compressor is connected to the suction pipe of the constant capacity compressor, and the lubricating oil flowing through the overflow pipe is Noh
If the constant force compressor is stopped, return to the variable capacity compressor.
An air conditioner characterized by being configured to be operated.