JPH01212875A - Multichamber air conditioner - Google Patents

Abstract

PURPOSE:To provide a normally stable freezer oil return amount irrespective of the magnitude of a capacity, by a method wherein an oil separator is connected to the delivery pipe of a capacity variable compressor and an accumulator to the suction pipe thereof, and an oil return pipe through which freezer oil separated by the oil separator is returned is connected to an accumulator. CONSTITUTION:Refrigerants containing freezer oil delivered from a speed variable compressor 2 and a pole variable compressor 3 are separated from freezer oil by means of oil separators 19 and 20, and flow to a 4-way valve 5 after the refrigerants are joined with each other. Freezer oil separated by the oil separators 19 and 20 flows to outlet pipes 23 and 24 through oil return pipes 27 and 28, and returns to the speed variable compressor 2 and the pole variable compressor 3 through which the freezer oil is delivered. The freezer oil not separated and flowing to the 4-way valve 5 together with a refrigerant makes around of a freezing cycle, and the freezer oil is distributed and branched in a ratio between circulating amounts together with a refrigerant in an amount matching the operation capacity of the speed variable compressor 2 and the pole variable compressor 3. The freezer oil is returned through accumulators 21 and 22 to the variable speed compressor 2 and the pole variable compressor 3.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to the return of refrigeration oil to the compressor of a refrigeration cycle in which a plurality of compressors of a multi-room air conditioner are connected in parallel.

BACKGROUND ART A conventional multi-room air conditioner will be explained with reference to FIGS. 5 and 6.

1 is an outdoor unit of a multi-room air conditioner, and a variable capacity compressor 2 (hereinafter referred to as a variable speed compressor in the text) is connected in parallel and changes its capacity by continuously changing the rotation speed. , the number of motor poles is 4.

A variable capacity compressor 3 that changes capacity in stages by changing between two poles (hereinafter referred to as a pole variable compressor), an oil separator 4
, four-way valve 5, outdoor electric expansion valve 6, outdoor heat exchanger 7,
An accumulator 8 and an outdoor fan 9 are installed. The outlet pipe 8A of the accumulator 8 has a shape that reaches approximately the bottom inside the accumulator 8 and then is bent upward by 180 degrees to reach the upper part of the road, and the tip thereof is open for communication.

Further, an oil return hole 8B is provided in communication with the bottom of the outlet pipe 8A. The oil separator 4 includes a variable speed compressor 2. A collective discharge pipe 10 that collects the discharge pipes 2A and 3A of the polar variable compressor 3
is connected to. Further, the accumulator 8 is also connected to the variable speed compressor 2. It is provided upstream of the branch pipe 11 before branching to the suction pipes 2B and 3B of the polar variable compressor 3. Reference numeral 12 denotes an oil return pipe, which is connected to communicate between the oil separator 4 and the accumulator 8. Reference numeral 13 indicates indoor units, which are connected in parallel to the outdoor unit 1, and are each equipped with an indoor electric expansion valve 14, an indoor heat exchanger 15, and an indoor fan 16 (indoor unit 1
3. The four indoor electric expansion valves 14, indoor heat exchangers 15, and indoor fans 16 are given suffixes A, B, C, and D, respectively, and when identified, they are referred to as indoor units 13A, 13B, etc. , In other cases, the indoor unit 18. indoor electric expansion valve 14). The variable speed compressor 2 changes the drive power frequency by an inverter 17, and 1. The pole variable compressor 3 changes its capacity by changing the number of motor poles, for example from 2 to 4, or vice versa, or by stopping the motor by changing the number of rotations using a pole number switch 18.

Next, the operation of the above configuration will be explained.

When the compressors 2 and 3 are activated, the compressed refrigerant is discharged from the respective discharge pipes 2A and 3A, and flows into the oil separator 4 via the collective discharge pipe 10. The oil separator 4 separates most of the refrigerating machine oil contained in the discharged refrigerant gas. The refrigerant flows from the oil separator 4 through the four-way valve 5 to the outdoor heat exchanger 6 during cooling, and to the indoor heat exchanger 15 during heating, passing through the indoor expansion valve 14 and the outdoor electric expansion valve 7. Thereafter, the indoor air flows from the four-way valve 5 to the accumulator 8 via the heat exchanger 15 or the outdoor heat exchanger 6. In the accumulator 8, the refrigerant is separated into gas and liquid, and only the refrigerant gas is passed through the branch pipe 11 to each variable speed compressor 2. Return to polar variable compressor 3. The refrigerating machine oil separated by the oil separator 4 passes through the oil return pipe 12 and is mixed with refrigerant gas at the outlet pipe 8A of the accumulator 8, and is then supplied to each variable speed compressor 2. It is returned to the polar variable compressor 3. Furthermore, the refrigerating machine oil that has not been separated by the oil separator 4 goes through the refrigerating cycle and is once stored in the accumulator, and then passes through the oil return hole 8B to the variable speed compressor 2. Return to polar variable compressor 3.

Variable speed compressor2. The variable speed compressor 3 starts up from the variable speed compressor 2 depending on the size of the indoor heat load.

As the heat load increases, the frequency of the inverter A17 is increased, and when the capacity becomes insufficient for the heat load even at the maximum frequency, the pole variable compressor 3 starts up and the pole number switch 18 changes the number of poles of the motor. Change the rotation speed by switching between 4 poles and 2 poles. Also, when the heat load decreases, the number of motor poles of the variable speed compressor 3 is switched between two and four poles, lowering the rotation speed, stopping first, and then controlling the capacity of the variable speed compressor 2. .゛Problems to be Solved by the Invention However, in the above configuration, if there is a difference in the rotation speed between one variable speed compressor 2 and the other extremely variable compressor 3 due to a change in capacity, the rotation speed generally changes. The higher the value, the more the amount of refrigerating machine oil contained in the discharged refrigerant increases in a quadratic manner. Therefore, the discharged refrigerating machine oil is distributed to the ratio of the refrigerant circulation amount of each variable capacity compressor and sucked in. As a result, the refrigerating machine oil in the compressor, which rotates at high speeds and discharges a large amount of refrigerant, gradually decreases, causing wear due to poor lubrication of mechanical parts, and burnout of the motor due to the resulting rise in temperature and increased mechanical loss. In addition, when the indoor heat load is reduced and the capacity is reduced, the internal diameter of the accumulator outlet pipe will experience a pressure drop even at the maximum refrigerant circulation rate.

Since it is designed to reduce the loss of refrigerant, the amount of refrigerant circulated is reduced and the refrigerant flow rate in the accumulator outlet pipe becomes extremely slow, preventing the refrigerating machine oil accumulated in the accumulator from being sucked in from the oil return hole. As refrigerating machine oil accumulates inside the compressor, the amount of refrigerating machine oil in the compressor decreases, which also causes major problems in terms of reliability, such as abnormal wear and motor burnout.

Therefore, the present invention solves the above-mentioned conventional problems, and improves the reliability of the compressor by always returning an appropriate amount of refrigerating machine oil to the compressor in accordance with the amount of refrigerating machine oil discharged from the compressor. be.

Means for Solving the Problem In order to solve this problem, the present invention comprises two variable capacity compressors connected in parallel, two oil separators, a four-way valve, an outdoor heat exchanger, an outdoor electric It consists of an outdoor unit equipped with an expansion valve and two accumulators, an indoor heat exchanger, an indoor electric expansion valve, and multiple indoor units connected in parallel. An oil separator is connected to the discharge pipe of the compressor, an accumulator is connected to the suction pipe, and an oil return pipe for returning the refrigerating machine oil separated by the oil separator is connected to the outlet pipe of the accumulator. be.

Effect of the present invention With the above-described configuration, different amounts of refrigerating machine oil discharged from each variable capacity compressor are separated by separate oil separators, and returned to each compressor as separated. A stable amount of refrigerating machine oil is always obtained regardless of the size of the oil.

Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the drawings, and components that are the same as those of the prior art will be denoted by the same reference numerals, and detailed explanation thereof will be omitted.

19.20 are variable speed compressors 2. This is an oil separator connected to the discharge pipes 2A and 3A of the polar variable compressor 3. 21.2
2 is an accumulator connected to the suction pipes 2B and 3B. 23.24 is the accumulator 21. The outlet pipe 25.26 of the accumulator 22 is the outlet pipe 23.
This is an oil return hole provided at substantially the bottom inside the accumulator 21, 22 of the outlet pipe 24. 27.28 is oil separator 19
20 and an oil return pipe provided between the outlet pipes 23 and 24.

Next, the operation of the above configuration will be explained. When the indoor heat load is small, for example when only the indoor unit Al 3A performs cooling and the other three units are stopped, only the variable speed compressor 2 operates. At this time, the refrigerant discharged from the discharge pipe 2A contains refrigerating machine oil and flows into the oil separator 19. Here, most of the refrigerating machine oil contained in the refrigerant is separated from the refrigerant, and the refrigerant and a very small amount of the refrigerating machine oil go to the outdoor heat exchanger 6 via the four-way valve 5. Refrigerating machine oil separated from the refrigerant in the oil separator 19 passes through an oil return pipe 27 to the accumulator 2.
It is mixed with refrigerant in the outlet pipe 23 of No. 1, and in this state returns to the variable speed compressor 2 through the suction pipe 2B. Furthermore, the refrigerating machine oil that was not separated by the oil separator 19 and flowed out together with the refrigerant goes through the refrigerating cycle and returns to the accumulator 21 . Accumulator 21
Then, the refrigerant is separated into gas and liquid, and at this time, the refrigerating machine oil is separated along with the liquid refrigerant and accumulates at the bottom of the accumulator 21.

Due to the difference in specific gravity between liquid refrigerant and refrigeration oil, refrigeration oil separates and accumulates at the bottom. Refrigerating machine oil is sucked in through the oil return hole 25 and returns to the variable speed compressor 2 together with the gas refrigerant through the outlet pipe 23 and the suction pipe 2B. At this time, the extremely variable compressor 3 is stopped, so the refrigerant circulating in the refrigeration cycle is completely transferred to the extremely variable compressor 3.
It doesn't flow.

When the indoor load increases, for example, when indoor units B and C start operating, the refrigerating capacity of the variable speed compressor 2 becomes insufficient, and the extremely variable compressor 3 starts up. Since the variable speed compressor 3 has a three-stage capacity control including stop, four-pole operation, and two-pole operation, the variable speed compressor 2 adjusts the capacity by lowering the inverter 170 frequency.

The refrigerant containing refrigerating machine oil discharged from the variable speed compressor 2 and the extremely variable compressor 3 is transferred to an oil separator 19 and an oil separator 20.
The refrigerating machine oil is separated from each other, combined, and then passed through the west valve 5.
heading towards. The refrigerating machine oil separated in the oil separators 19 and 20 flows to outlet pipes 23 and 24 through oil return pipes 27 and 24 to outlet pipes 23 and 24, respectively. The discharged air returns to the variable speed compressor 2 and extremely variable compressor 3, respectively. Further, the unseparated refrigeration oil that has flowed together with the refrigerant to the four-way valve 5 goes around the refrigeration cycle and similarly accumulates at the bottom of the accumulators 21 and 22. At this time, when the flow is divided into both accumulators 21 and 22, the variable speed compressor 2. A circulating amount of refrigerant commensurate with the operating capacity of the extremely variable compressor 3 is distributed to each of them, and naturally, refrigerating machine oil is also distributed and distributed according to the ratio of the circulating amount. The refrigerating machine oil is then transferred from the accumulators 21 and 22 to the variable speed compressors 2 and 2, respectively. Return to polar variable compressor 3.

Furthermore, since most of the refrigerating machine oil contained in the discharged refrigerant is separated by the oil separator 19, 20, the total amount of refrigerating machine oil in both paths is approximately equal to the amount of refrigerating machine oil discharged.

Effects of the Invention As is clear from the above explanation, the multi-room air conditioner of the present invention includes two variable capacity compressors connected in parallel, two oil separators, a four-way valve, and an outdoor heat exchanger. It consists of an outdoor unit with an outdoor electric expansion valve, an outdoor electric expansion valve, and two accumulators, an indoor heat exchanger, an indoor electric expansion valve, and multiple indoor units connected in parallel. An oil separator is connected to the discharge pipe of the connected variable capacity compressor, and an accumulator is connected to the suction pipe, and an oil return pipe for returning the refrigerating machine oil separated by the oil separator is connected to the outlet pipe of the accumulator. Different amounts of refrigerating machine oil are discharged together with the refrigerant from the two variable capacity compressors, and each discharged amount is returned to the two variable capacity compressors, so the amount of refrigerating machine oil discharged is returned to the variable capacity compressor at a different rate from the amount of refrigerating oil discharged. When the refrigerating machine oil returns, the refrigerating machine oil in one of the variable capacity compressors decreases abnormally, and there are no problems such as abnormal wear of mechanical parts or burnout of motor windings due to lack of refrigerating machine oil, which greatly improves reliability. It has a great effect.

[Brief explanation of the drawing]

Fig. 1 is a refrigeration cycle diagram of a multi-room air conditioner which is an embodiment of the present invention, Fig. 2 is a sectional view of the accumulator shown in Fig. 1, and Fig. 3 is a refrigeration cycle diagram of a conventional multi-room air conditioner. The cycle diagram, FIG. 4, is a sectional view of the accumulator of FIG. 3. DESCRIPTION OF SYMBOLS 1... Outdoor unit, 2... Variable speed compressor, 3... Pole variable compressor, 5... Four-way valve, 6... Outdoor electric expansion valve,
7...Outdoor heat exchanger, 13...Indoor unit, 14...
・Indoor electric expansion valve, 15... Indoor heat exchanger, 19
．． 20...Oil separator, 21.22...Accumulator. Name of agent: Patent attorney Toshio Nakao Baka 1 21.22
-m-Accumulator No. 20 \ Do5 (26) No. 30 Fig. 4

Claims (1)

[Claims] An outdoor unit with two variable capacity compressors connected in parallel, two oil separators, a four-way valve, an outdoor heat exchanger, an outdoor electric expansion valve, and two accumulators, and an indoor heat exchanger. It consists of a plurality of indoor units connected in parallel, an oil separator is connected to the discharge pipe of the variable capacity compressor connected in parallel, and an accumulator is connected to the suction pipe. , a multi-room air conditioner in which oil return pipes for returning refrigerating machine oil separated by the oil separator are respectively connected to outlet pipes of the accumulator;