JPH10170079A - Air conditioning system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable oil contained in refrigerant to be returned to an outdoor device in a short period of time without changing a diameter of a refrigerant pipe. SOLUTION: This system is constructed such that an indoor device 3 is installed at each of floors in an building 1 and an outdoor device 9 connected to each of the indoor devices 3 is arranged at a higher position than the indoor device 3. In this case, the lower end of a refrigerant thick pipe 5 connecting the outdoor device 9 with the indoor device 3 is provided with an oil returning device 30 having means for temporarily storing oil contained in the refrigerant and returning this oil to the outdoor device.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioning system having an oil return unit for returning oil contained in a refrigerant to an outdoor unit.

[0002]

2. Description of the Related Art In general, an air conditioning system is known which includes an outdoor unit and a plurality of indoor units, and each indoor unit is arranged on each floor of a building. In this type, since the length of the refrigerant pipe is generally increased, the amount of the refrigerant charged in the refrigeration cycle is increased.

Therefore, the time required for the refrigerant to return to the compressor of the outdoor unit by circulating through the indoor units arranged on each floor of the building is inevitably increased.

[0004]

If the return time of the refrigerant becomes longer, the return time of the oil circulating with the refrigerant becomes longer, which may cause a shortage of oil in the compressor. In the conventional air conditioning system, the length of the refrigerant pipe is set to, for example, 1
If the length is not less than 00 m, oil shortage actually occurs. Therefore, when the length of the refrigerant pipe is extended beyond that, the pipe diameter is changed to shorten the oil return time. .

Accordingly, an object of the present invention is to solve the problems of the prior art and to return oil contained in refrigerant to an outdoor unit in a short time without changing the pipe diameter of the refrigerant pipe. An object of the present invention is to provide an air-conditioning system that can be used.

[0006]

According to the first aspect of the present invention, there is provided an air conditioning system in which an indoor unit is installed on each floor of a building, and an outdoor unit connected to each indoor unit is located higher than each indoor unit. At the lower end of the thick refrigerant pipe connecting the outdoor unit and the indoor unit, temporarily store oil contained in the refrigerant,
Further, an oil return unit having means for returning the oil to the outdoor unit is provided.

According to a second aspect of the present invention, there is provided an air conditioning system in which an indoor unit is installed on each floor of a building and an outdoor unit connected to each indoor unit is arranged at a higher position than each indoor unit. An oil reservoir for temporarily storing oil contained in the refrigerant at the lower end of the thick refrigerant pipe connecting the unit and the oil reservoir and the outdoor unit, and the oil stored in the oil reservoir for the outdoor unit. An oil return unit having a return pipe dedicated to returning oil and a pump provided in the return pipe dedicated to oil is provided.

According to a third aspect of the present invention, there is provided an air conditioning system in which an indoor unit is installed on each floor of a building and an outdoor unit connected to each indoor unit is arranged at a higher position than each indoor unit. An oil reservoir for temporarily storing oil contained in the refrigerant at the lower end of the thick refrigerant pipe connecting the unit and the oil reservoir and the outdoor unit, and the oil stored in the oil reservoir for the outdoor unit. When the oil stored in the oil reservoir is returned to the outdoor unit by connecting any of the oil reservoir and the refrigerant thick tube or the refrigerant thin tube to the oil return tube, the oil inside the refrigerant thick tube or the pressure in the refrigerant thin tube is returned to the oil. An oil return unit having pressure applying means for applying pressure is provided.

According to a fourth aspect of the present invention, there is provided an air conditioning system in which an indoor unit is installed on each floor of a building and an outdoor unit connected to each indoor unit is arranged at a higher position than each indoor unit. An oil reservoir for temporarily storing oil contained in the refrigerant is provided at the lower end of the refrigerant thick pipe connecting the unit and the oil, which is provided in the oil reservoir and is used for returning the oil stored in the oil reservoir to the outdoor unit. An oil return unit having an oil vaporizing means for vaporizing is provided.

According to a fifth aspect of the present invention, there is provided an air conditioning system in which an indoor unit is installed on each floor of a building and an outdoor unit connected to each indoor unit is arranged at a lower position than each indoor unit. An oil reservoir that temporarily stores oil contained in the refrigerant in a thick refrigerant pipe that connects the unit and an oil reservoir that connects the oil reservoir to an outdoor unit and returns the oil stored in the oil reservoir to the outdoor unit. An oil return unit having a return pipe is provided.

[0011]

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

In FIG. 1, reference numeral 1 denotes a building, and two indoor units 3 are installed on each floor of the building 1, respectively. One indoor unit 9 is connected to each indoor unit 3 via a thick refrigerant pipe 5 and a thin refrigerant tube 7, and the outdoor unit 9 is arranged at a higher place than each indoor unit 3, for example, on the roof of the building 1. ing. An oil return unit 30, which will be described later, is provided at the lower end 5a of the refrigerant thick tube 5 connecting the outdoor unit 9 and the indoor unit 3.

Referring to FIG. 2, the refrigerant cycle according to the present embodiment will be described.
1, compressor 13, oil separator 15, four-way valve 17,
And an outdoor heat exchanger 19 and the like, which are sequentially connected via a refrigerant pipe. The outdoor heat exchanger 19 is connected to the indoor mechanical valve 21 of each indoor unit 3 and the indoor heat exchanger 22 via the above-described refrigerant thin tube 7, and the indoor heat exchanger 22 is connected to the refrigerant large tube 5. Four-way valve 1 for outdoor unit 9
It is connected to 7.

As shown in FIG. 3, the oil return unit 30 has an oil reservoir 31 for temporarily storing oil contained in the refrigerant, a lower end 31a of the oil reservoir 31, and an inlet of the accumulator 11 of the outdoor unit 9. 2 (see FIG. 2), an oil-only return pipe 33 for returning the oil stored in the oil sump 31 to the outdoor unit 9, a pump 35 provided in the oil-only return pipe 33, and an electric valve 37 are built in. You.

During the cooling operation, the four-way valve 17 is switched to the position indicated by the dotted line, and the refrigerant flows in the direction indicated by the dotted arrow. At this time, the outdoor heat exchanger 19 functions as a condenser,
The indoor heat exchanger 22 functions as an evaporator, and a cooling operation is performed. During the heating operation, the four-way valve 17 is switched to the position indicated by the solid line, and the refrigerant flows in the direction indicated by the solid line arrow. At this time, the outdoor heat exchanger 19 functions as an evaporator, and the indoor heat exchanger 22 functions as a condenser, and a heating operation is performed.

During these cooling and heating operations, oil contained in the refrigerant is accumulated in the oil sump 31 while circulating between the outdoor unit 9 and each indoor unit 3.

For example, during the cooling operation, referring to FIG. 1, the liquid refrigerant (dotted arrow) flows from bottom to top in the thick refrigerant pipe 5, that is, from each indoor unit 3 to the outdoor unit 9. flow,
The oil separates and falls in the thick refrigerant pipe 5 and accumulates in the oil sump 31 of the oil return unit 30. At the time of the heating operation, referring to FIG. 1, the gas refrigerant (solid line arrow) flows from top to bottom in the thick refrigerant pipe 5, that is,
Flows toward each indoor unit 3, the oil is separated within the thick refrigerant pipe 5 and falls directly below, and the oil return unit 3
It is stored in the oil reservoir 31 of 0.

According to this embodiment, the oil sump 31
When the oil accumulates, the electric valve 37 is opened and the pump 35 is driven (FIG. 3), and the oil is pumped up through the oil return pipe 33, and the inlet of the accumulator 11 of the outdoor unit 9 (FIG. 2). Through the two compressors 13.

Whether or not oil has accumulated in the oil reservoir 31 is determined, for example, based on a signal indicating oil shortage from an oil sensor (not shown) attached to the compressor 13 or the like. Alternatively, it may be estimated from the operation time of the air conditioning system.

Since the oil is pumped up using the pump 35, the diameter of the refrigerant thick pipe 5 can be reduced without reducing the diameter.
The oil can be returned to the outdoor unit 9 in a short time.
Therefore, pressure loss can be reduced without adding resistance to the flow of the refrigerant. Moreover, the length of the refrigerant pipe is not limited, and an effect such as providing an air conditioning system free of the pipe length can be obtained.

FIG. 4 shows another embodiment. In this air conditioning system, an oil return unit 40 is provided at the lower end of the refrigerant large tube 5 and the refrigerant thin tube 7 that connect the outdoor unit 9 and the indoor unit 3. This oil return unit 40
Has an oil reservoir 41 for temporarily storing oil contained in the refrigerant, as shown in FIG.
The large refrigerant pipe 5 is connected to the upper end 41 b of the first through a check valve 42, and the small refrigerant pipe 7 is connected to the capillary tube 44 and the first electric valve 43. Note that the order of connection between the first motor-operated valve 43 and the capillary tube 44 may be the reverse of the order shown in FIG.

An oil return pipe 45 is connected to the lower end 41a of the oil reservoir 41, and a second electric valve 46 and a third electric valve 47 are connected in series to the oil return pipe 45. . Further, a bypass pipe 48 for bypassing the third electric valve 47 is connected, and a capillary tube 49 is connected to the bypass pipe 48. Then, the oil return pipe 45 is connected to the inlet (for example, FIG. 2) of the accumulator 11 of the outdoor unit 9 as in the case of FIG.

According to this embodiment, if oil is accumulated in the oil reservoir 41 in the same manner as in FIG. 1 during heating, only the second motor-operated valve 46 is opened.

Then, as shown by a solid arrow in FIG. 5, high-pressure gas refrigerant flows into the oil reservoir 41 from the thick refrigerant pipe 5 through the check valve 42, and the second electric valve 46 The oil is extruded through. This oil is pushed out through the capillary tube 49 and is returned to the compressor 13 from the inlet of the outdoor unit 9, for example, the accumulator 11 (FIG. 2) through the oil return pipe 45.

As described above, during the heating operation, the oil sump 4
The pressure in the refrigerant thick pipe 5 is added to the oil accumulated in 1,
The oil is returned to the compressor 13 by this pressure. Here, the second motor-operated valve 46 constitutes a pressure applying means.

During cooling, if oil is accumulated in the oil reservoir 41 in the same manner as in FIG. 1, all of the first to third electric valves 43, 46 and 47 are opened.

Then, as shown by a dotted arrow in FIG. 5, a high-pressure liquid refrigerant flows into the oil reservoir 41 from the refrigerant tube 7 through the first electric valve 43, and the oil reservoir 4
The oil is pushed out from the first through the second electric valve 46. This oil is pushed out through the third motor-operated valve 47 and is returned to the compressor 13 from the inlet of the outdoor unit 9, for example, the accumulator 11 (FIG. 2) through the oil return pipe 45.

As described above, during cooling, the pressure in the refrigerant tube 7 is applied to the oil stored in the oil sump 41, and the oil is returned to the compressor 13 by this pressure. Here, the first to third electric valves 43, 46, 47 constitute pressure applying means.

Whether or not oil has accumulated in the oil sump 41 is determined, for example, based on a signal indicating oil shortage from an oil sensor (not shown) attached to the compressor 13 or the like. Alternatively, it may be estimated from the operation time of the air conditioning system.

According to this embodiment, the oil sump 41
Pressure is applied to the oil that accumulates in the oil, and the oil is returned by this pressure, so that the time for returning the oil is reduced.

FIG. 6 shows still another embodiment.
In this system, an oil return unit 50 is provided at the lower end of the thick refrigerant pipe 5 connecting the outdoor unit 9 and each indoor unit 3. As shown in FIG. 7, the oil return unit 50 has an oil reservoir 51 for temporarily storing the oil contained in the refrigerant, and the oil reservoir 51 stores the oil stored in the oil reservoir 51 outside the oil reservoir. When returning to the machine 9, oil vaporizing means 53 for vaporizing oil is provided. The oil vaporizing means 53 is specifically configured by a vibrator that gives vibration to stored oil.

According to this embodiment, when oil is accumulated in the oil reservoir 51 in the same manner as that shown in FIG. 1, the vibrator 53 is driven, and the vibration causes the oil to evaporate. Is returned to the compressor 13 through the thick refrigerant pipe 5.

Whether or not oil has accumulated in the oil sump 61 is determined, for example, based on a signal indicating oil shortage from an oil sensor (not shown) attached to the compressor 13 or the like. Alternatively, it may be estimated from the operation time of the air conditioning system.

According to this embodiment, the oil sump 51
Vibration is applied to the oil that accumulates in the oil to vaporize the oil, and the vaporized oil is returned to the compressor 13 through the thick refrigerant pipe 5, so that a dedicated oil return pipe is not required, and the time for returning the oil is reduced.

FIG. 8 shows still another embodiment.
In this system, first, the outdoor unit 9 is installed on the ground.
An oil return unit 60 is provided at the bottom of the thick refrigerant pipe 5 connecting the outdoor unit 9 and each indoor unit 3. As shown in FIG. 9, the oil return unit 60 has an oil reservoir 61 for temporarily storing oil contained in the refrigerant, and the oil stored in the oil reservoir 61 is For example, the accumulator 11 of the outdoor unit 9
An oil-only return pipe 63 returning to the compressor 13 through an inlet (FIG. 2) is connected to the oil-only return pipe 63, and an electric valve 65 and a capillary tube 67 are connected to the oil-only return pipe 63. The order of connection between the motor-operated valve 65 and the capillary tube 67 may be opposite to that shown in FIG.

According to this embodiment, the motor-operated valve 65 is opened when oil is accumulated in the oil reservoir 61 in the same manner as that shown in FIG. 1 during the heating operation. Then, the oil is returned to the compressor 9 through the oil-only return pipe 63 so as to be pushed out by the pressure of the high-pressure gas refrigerant flowing in the large refrigerant pipe 5.

Whether or not oil has accumulated in the oil sump 61 is determined, for example, based on a signal indicating oil shortage from an oil sensor (not shown) attached to the compressor 13 or the like. Alternatively, it may be estimated from the operation time of the air conditioning system.

When the air-conditioning system performs the cooling operation, the oil is returned to the compressor 9 through the refrigerant tubes 7. However, since the outdoor unit 9 is located below the indoor unit 3, the oil easily returns during cooling, and there is no problem in returning the oil.

Although the present invention has been described with reference to an embodiment, it is apparent that the present invention is not limited to this. For example, as a portion for temporarily storing oil, in the above embodiments, it is expressed as "oil reservoir", but this may be a tank, for example, a part of a refrigerant thick pipe. Good.

[0040]

According to these inventions, the oil return unit having means for temporarily storing the oil contained in the refrigerant and returning the oil to the outdoor unit is provided. Oil can be returned to the compressor.

[Brief description of the drawings]

FIG. 1 is a system diagram showing an embodiment of an air conditioning system according to the present invention.

FIG. 2 is also a refrigerant circuit diagram.

FIG. 3 is a circuit diagram of an oil return unit.

FIG. 4 is a system diagram showing another embodiment.

FIG. 5 is a circuit diagram of the oil return unit.

FIG. 6 is a system diagram showing still another embodiment.

FIG. 7 is a circuit diagram of the oil return unit.

FIG. 8 is a system diagram showing still another embodiment.

FIG. 9 is a circuit diagram of the oil return unit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Building 3 Indoor unit 5 Refrigerant thick tube 7 Refrigerant thin tube 9 Outdoor unit 13 Compressor 19 Outdoor heat exchanger 22 Indoor heat exchanger 30, 40, 50, 60 Oil return unit 31, 41, 51, 61 Oil reservoir 33, 45 , 63 Oil return pipe 53 Oil vaporization means

Claims (5)

[Claims] 1. An air conditioning system in which an indoor unit is installed on each floor of a building, and an outdoor unit connected to each indoor unit is arranged at a higher position than each indoor unit. A refrigerant thick tube connecting the outdoor unit and the indoor unit An air conditioning system comprising: an oil return unit having means for temporarily storing oil contained in a refrigerant and returning the oil to an outdoor unit at a lower end of the air conditioner. 2. An air conditioning system in which an indoor unit is installed on each floor of a building, and an outdoor unit connected to each indoor unit is located at a higher position than each indoor unit. A refrigerant refrigerant pipe connecting the outdoor unit and the indoor unit An oil reservoir for temporarily storing oil contained in the refrigerant, an oil-only return pipe connecting the oil reservoir to an outdoor unit, and returning the oil stored in the oil reservoir to the outdoor unit at a lower end of the oil reservoir; An air conditioning system comprising: an oil return unit having a pump provided in the oil return pipe. 3. An air conditioning system in which an indoor unit is installed on each floor of a building, and an outdoor unit connected to each indoor unit is arranged at a higher position than each indoor unit, wherein a refrigerant thick tube connecting the outdoor unit and the indoor unit is provided. An oil reservoir for temporarily storing oil contained in the refrigerant, an oil-only return pipe connecting the oil reservoir to an outdoor unit, and returning the oil stored in the oil reservoir to the outdoor unit at a lower end of the oil reservoir; Pressure adding means for connecting the oil reservoir and either the refrigerant thick tube or the refrigerant thin tube, and applying pressure inside the refrigerant thick tube or the refrigerant thin tube to the oil when returning the oil stored in the oil reservoir to the outdoor unit. An air conditioning system comprising an oil return unit having 4. An air conditioning system in which an indoor unit is installed on each floor of a building, and an outdoor unit connected to each indoor unit is located at a higher position than each indoor unit, wherein a refrigerant thick pipe connecting the outdoor unit and the indoor unit is provided. An oil reservoir for temporarily storing oil contained in the refrigerant, and oil vaporizing means provided in the oil reservoir for vaporizing the oil when returning the oil stored in the oil reservoir to the outdoor unit at a lower end portion of the oil reservoir. An air conditioning system comprising an oil return unit having 5. An air conditioning system in which an indoor unit is installed on each floor of a building and an outdoor unit connected to each indoor unit is located at a lower position than each indoor unit, wherein a refrigerant thick pipe connecting the outdoor unit and the indoor unit is provided. An oil reservoir having an oil reservoir for temporarily storing oil contained in the refrigerant, an oil exclusive return pipe connecting the oil reservoir to an outdoor unit, and returning the oil stored in the oil reservoir to the outdoor unit. An air conditioning system comprising a unit.