JPH1073330A - Refrigerator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a refrigerator wherein the oil collected in a gas-liquid separator is returned uniformly to separate refrigerant compressors without being affected by the turbulence of an oil level and the compressor is prevented from coming to be out of order due to the lowering of the oil level. SOLUTION: In this refrigerator, a first refrigerant compressor 1 and a second refrigerant compressor 2 having the same capacity and provided in parallel, a condenser 3, a pressure-reducing device 4, an evaporator 5, a gas-liquid separator 6, etc., are arranged sequentially like a circuit. A first suction piping 7 and a second suction piping 8 connecting respectively the upper part of the gas-liquid separator 6 with the suction sides of the refrigerant compressors 1 and 2 in parallel and a first oil return piping 9 and a second oil return piping 10 connecting respectively the lower part of the gas-liquid separator 6 with the suction sides of the refrigerant compressors 1 and 2 in parallel are provided. The respective intra-pipe sectional areas and piping lengths of the oil return pipings 9 and 10 are set to be identical.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerating apparatus used for a supermarket showcase, a refrigerator, a freezer, and the like.

[0002]

2. Description of the Related Art FIG. 9 is a refrigerant piping system diagram showing a conventional refrigeration system having two refrigerant compressors mounted in parallel, and FIG. 10 is a sectional view showing a gas-liquid separator of the conventional refrigeration system. In each figure, 1 and 2 are two refrigerant compressors arranged in parallel, 3 is a condenser, 4 is a decompression device, 5 is an evaporator, and 6 is a gas-liquid separator. Inside the gas-liquid separator 6, an inlet pipe 36, U-shaped suction pipes 29, 30 provided with oil return holes 31, 32, and the like are provided, and communicate with the suction pipes 7, 8.

Next, the operation will be described. The high-temperature and high-pressure refrigerant compressed by the refrigerant compressors 1 and 2 is supplied to the condenser 8
Is condensed and liquefied. The liquid refrigerant passes through a refrigerant pipe (not numbered), is decompressed by the decompression device 4 to be in a gas-liquid two-phase state, exchanges heat with the outside air in the evaporator 5, and loads in a showcase such as a refrigerator, a freezer, and a supermarket. To cool.
The heat exchanged with the outside air is gasified and flows into the gas-liquid separator 6 through the inlet pipe 36. At this time, a small amount of oil contained in the high-temperature and high-pressure gas discharged from the refrigerant compressors 1 and 2 also passes through the circuit and accumulates in the gas-liquid separator 6. The refrigerant is a gas-liquid separator 6
Openings 29a, 30 at the tips of U-shaped suction pipes 29, 30 inside
a, and returns to the refrigerant compressors 1 and 2 through the suction pipes 7 and 8, respectively, and repeats the above cycle. On the other hand, the oil accumulated in the gas-liquid separator 6 is sucked up from the oil return holes 31 and 32 at the lower part, returned to the refrigerant compressors 1 and 2 through the suction pipes 7 and 8, respectively, and accumulated. The oil level at the bottom of the gas-liquid separator 6 is often disturbed due to the inlet pipe 36 facing downward and the blowing of refrigerant / oil. Therefore, depending on the degree of turbulence of the oil level in the gas-liquid separator 6, one of the oil level may be higher than the oil return hole and the other may have an oil level lower than the oil return hole. The amount of oil in the other refrigerant compressor increases, and the amount of oil in the refrigerant compressor in which oil has not reached the oil return hole decreases.

[0004]

As described above, in the conventional refrigeration system, the amount of oil sucked up from the oil return hole of each U-shaped suction pipe depends on the position of the oil return hole and the degree of disturbance of the oil level in the vessel. Each may not be equal. Therefore, the oil level in the refrigerant compressor in which the amount of oil to be sucked is smaller decreases, and if such a state continues for a long time, the compressor may be damaged due to oil depletion.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and the oil accumulated in the gas-liquid separator is supplied to each refrigerant compressor without being affected by the turbulence of the oil surface. An object of the present invention is to provide a refrigeration apparatus that is returned to a uniform state and does not cause a problem due to a decrease in oil level of a compressor.

[0006]

In order to achieve the above object, a refrigeration apparatus according to the present invention comprises a plurality of refrigerant compressors, condensers, decompression devices, evaporators having the same capacity and provided in parallel. Along with sequentially disposing the gas-liquid separator and the like in a circuit shape, a plurality of suction pipes connecting the upper part of the gas-liquid separator and the suction sides of the plurality of refrigerant compressors in parallel, and a lower part of the gas-liquid separator. In a refrigerating apparatus including a plurality of oil return pipes that respectively connect the suction sides of a plurality of refrigerant compressors in parallel,
The plurality of oil return pipes are configured such that the cross-sectional area in the pipe and the pipe length are set to be the same.

In addition, a plurality of refrigerant compressors, condensers, decompression devices, evaporators, gas-liquid separators, etc., having the same capacity and provided in parallel, are sequentially arranged in a circuit form. A plurality of suction pipes for connecting the suction sides of the plurality of refrigerant compressors in parallel, and a plurality of oil return pipes for connecting the lower part of the gas-liquid separator and the suction sides of the plurality of refrigerant compressors in parallel, respectively. In the refrigerating apparatus provided with, the plurality of oil return pipes are large within a range where the pressure loss in each oil return pipe is smaller than the pressure loss in the suction pipe connected to the same refrigerant compressor. It is configured by setting to the pipe length.

[0008] A plurality of refrigerant compressors, condensers, decompression devices, evaporators, gas-liquid separators and the like, which are provided in parallel with the same capacity, are sequentially arranged in a circuit form. A plurality of suction pipes for connecting the suction sides of the plurality of refrigerant compressors in parallel, and a plurality of oil return pipes for connecting the lower part of the gas-liquid separator and the suction sides of the plurality of refrigerant compressors in parallel, respectively. And a plurality of oil return pipes, the capillary tubes satisfying a condition that a pressure loss in each oil return pipe is smaller than a pressure loss in a suction pipe connected to the same refrigerant compressor. It is composed of

Further, a plurality of refrigerant compressors, condensers, decompression devices, evaporators, gas-liquid separators, etc., which are provided in parallel with the same capacity, are sequentially arranged in a circuit form, and the upper part of the gas-liquid separator and A plurality of suction pipes for connecting the suction sides of the plurality of refrigerant compressors in parallel, and a plurality of oil return pipes for connecting the lower part of the gas-liquid separator and the suction sides of the plurality of refrigerant compressors in parallel, respectively. Orifice in a plurality of oil return pipes, the pressure loss in each oil return pipe being smaller than the pressure loss in the suction pipe connected to the same refrigerant compressor. Is provided.

In addition, a plurality of refrigerant compressors, condensers, decompression devices, evaporators, gas-liquid separators, etc., which are provided in parallel with different capacities, are sequentially arranged in a circuit form. A plurality of suction pipes each connecting the suction side of the refrigerant compressor in parallel, and a plurality of oil return pipes each connecting the bottom of the gas-liquid separator and the suction side of the plurality of refrigerant compressors in parallel. In the refrigerating apparatus equipped with the above, the plurality of oil return pipes are each set to the same pipe length, and the pressure loss in each oil return pipe is equal to the pressure in the suction pipe connected to the same refrigerant compressor. The configuration is such that the cross-sectional area in the pipe is set within a range in which the loss is smaller than the loss and according to the capacity ratio of the plurality of refrigerant compressors.

A plurality of refrigerant compressors, condensers, decompression devices, evaporators, gas-liquid separators, etc., having different capacities and provided in parallel, are sequentially arranged in a circuit form, and the upper part of the gas-liquid separator and the plural A plurality of suction pipes each connecting the suction side of the refrigerant compressor in parallel, and a plurality of oil return pipes each connecting the bottom of the gas-liquid separator and the suction side of the plurality of refrigerant compressors in parallel. In the refrigerating apparatus provided with, the plurality of oil return pipes are each set to the same pipe cross-sectional area, and the pressure loss in each oil return pipe is within the suction pipe connected to the same refrigerant compressor. The pipe length is set within a range where the pressure loss is smaller than the pressure loss and according to the capacity ratio of the plurality of refrigerant compressors.

Further, a plurality of refrigerant compressors, condensers, decompression devices, evaporators, gas-liquid separators, etc., which are provided in parallel with different capacities, are sequentially arranged in a circuit form. A plurality of suction pipes each connecting the suction side of the refrigerant compressor in parallel, and a plurality of oil return pipes each connecting the bottom of the gas-liquid separator and the suction side of the plurality of refrigerant compressors in parallel. In the refrigeration apparatus provided with, the plurality of oil return pipes, within a range in which the pressure loss in each oil return pipe is smaller than the pressure loss in the suction pipe connected to the same refrigerant compressor, and The cross-sectional area in the pipe and the pipe length are set according to the capacity ratio of the plurality of refrigerant compressors.

A plurality of refrigerant compressors, condensers, decompression devices, evaporators, gas-liquid separators, etc., having the same capacity and provided in parallel, are sequentially arranged in a circuit form. A plurality of suction pipes for connecting the suction sides of the plurality of refrigerant compressors in parallel, and a plurality of oil return pipes for connecting the lower part of the gas-liquid separator and the suction sides of the plurality of refrigerant compressors in parallel, respectively. In a refrigeration system comprising: a plurality of solenoid valves provided for each of a plurality of oil return pipes, and a first control unit that periodically opens and closes each solenoid valve so that the opening time of each solenoid valve is equal. Is provided.

A plurality of refrigerant compressors, condensers, decompression devices, evaporators, gas-liquid separators, etc., having the same capacity and provided in parallel, are sequentially arranged in a circuit form. A plurality of suction pipes for connecting the suction sides of the plurality of refrigerant compressors in parallel, and a plurality of oil return pipes for connecting the lower part of the gas-liquid separator and the suction sides of the plurality of refrigerant compressors in parallel, respectively. And a three-way valve that is provided at a branch position from the lower part of the gas-liquid separator to a plurality of oil return pipes and switches an oil flow path from the gas-liquid separator to be able to communicate with each oil return pipe. And a second control unit that periodically switches the oil flow path of the three-way valve toward each oil return pipe so that the communication time to each oil return pipe is equalized.

Further, a plurality of refrigerant compressors, condensers, decompression devices, evaporators, gas-liquid separators, etc., which are provided in parallel with different capacities, are sequentially arranged in a circuit form. A plurality of suction pipes each connecting the suction side of the refrigerant compressor in parallel, and a plurality of oil return pipes each connecting the bottom of the gas-liquid separator and the suction side of the plurality of refrigerant compressors in parallel. In the refrigeration apparatus, a plurality of solenoid valves provided for each of a plurality of oil return pipes, and a third control unit that opens and closes each solenoid valve so that the opening time according to the capacity ratio of each refrigerant compressor, and Is provided.

In addition, a plurality of refrigerant compressors, condensers, decompression devices, evaporators, gas-liquid separators, etc., which are provided in parallel with different capacities, are sequentially arranged in a circuit form, and the upper part of the gas-liquid separator and A plurality of suction pipes each connecting the suction side of the refrigerant compressor in parallel, and a plurality of oil return pipes each connecting the bottom of the gas-liquid separator and the suction side of the plurality of refrigerant compressors in parallel. A three-way valve provided at a branch position from the lower part of the gas-liquid separator to a plurality of oil return pipes and switching an oil flow path from the gas-liquid separator to be able to communicate with each oil return pipe, And a fourth control unit that switches the oil flow path of the three-way valve toward each oil return pipe so that the communication time is in accordance with the capacity ratio of each refrigerant compressor.

A plurality of refrigerant compressors, condensers, decompression devices, evaporators, gas-liquid separators, etc., having different capacities and arranged in parallel, are sequentially arranged in a circuit form, and the upper part of the gas-liquid separator and the plural A plurality of suction pipes each connecting the suction side of the refrigerant compressor in parallel, and a plurality of oil return pipes each connecting the bottom of the gas-liquid separator and the suction side of the plurality of refrigerant compressors in parallel. A plurality of solenoid valves provided for each of a plurality of oil return pipes, and a plurality of oil levels provided respectively for a plurality of refrigerant compressors and operating when an oil level in the compressor falls below a predetermined level. It comprises a detector and a fifth control unit that opens an electromagnetic valve associated with the oil level detector when the oil level detector operates.

Further, a plurality of refrigerant compressors, condensers, decompression devices, evaporators, gas-liquid separators, etc., which are provided in parallel with different capacities, are sequentially arranged in a circuit form. A plurality of suction pipes each connecting the suction side of the refrigerant compressor in parallel, and a plurality of oil return pipes each connecting the bottom of the gas-liquid separator and the suction side of the plurality of refrigerant compressors in parallel. A three-way valve provided at a branch position from the lower part of the gas-liquid separator to a plurality of oil return pipes and switching an oil flow path from the gas-liquid separator to be able to communicate with each oil return pipe, A plurality of oil level detectors respectively provided in the plurality of refrigerant compressors and operating when an oil level in the compressor falls below a predetermined level, and an oil return pipe associated with the oil level detector when the oil level detector operates Control section that switches the oil flow path of the three-way valve toward Are those configured by including the.

A plurality of refrigerant compressors, condensers, decompression devices, evaporators, gas-liquid separators, etc., which are provided in parallel with different capacities, are sequentially arranged in a circuit form, and the upper part of the gas-liquid separator and A plurality of suction pipes each connecting the suction side of the refrigerant compressor in parallel, and a plurality of oil return pipes each connecting the bottom of the gas-liquid separator and the suction side of the plurality of refrigerant compressors in parallel. A plurality of solenoid valves provided for each of a plurality of oil return pipes, and a plurality of oil levels provided respectively for a plurality of refrigerant compressors and operating when an oil level in the compressor falls below a predetermined level. Detector and each solenoid valve are opened and closed periodically, and each solenoid valve is set according to the earlier of the periodic timing when each solenoid valve is opened and when the oil level detector associated with each solenoid valve operates. And a seventh control unit for releasing It is what is.

[0020]

Embodiments of the present invention will be described with reference to the drawings. Embodiment 1 of the Invention FIG. 1 shows a refrigeration apparatus according to Embodiment 1 of the present invention.
This shows a case where the units are mounted in parallel. In the drawing, 1 is a first refrigerant compressor, 2 is a second refrigerant compressor having the same capacity as the first refrigerant compressor 1 and provided in parallel, 3 is a condenser, 4 is a decompression device,
Reference numeral 5 denotes an evaporator, reference numeral 6 denotes a gas-liquid separator, reference numeral 7 denotes a first suction pipe connecting an outlet 6c at an upper portion of the gas-liquid separator 6 and a suction side of the first refrigerant compressor 1, and reference numeral 8 denotes an upper portion of the gas-liquid separator 6. A second suction pipe 9 connecting an outlet 6b of the second refrigerant compressor 2 to the suction side of the second refrigerant compressor 2 exits from an oil outlet 6d below the gas-liquid separator 6 and is connected to a connection 7a of the first suction pipe 7. The first oil return pipe 10 is a second oil return pipe that exits from the oil take-out part 6 d below the gas-liquid separator 6 and is connected to the connection part 8 a of the second suction pipe 8. In this case, the first oil return pipe 9 and the second oil return pipe 10 are set to have the same cross-sectional area and the same pipe length.

The refrigeration apparatus according to Embodiment 1 is configured as described above. Subsequently, the operation of the refrigeration apparatus will be described. First, the first refrigerant compressor 1 and the second refrigerant compressor 2
The high-temperature and high-pressure refrigerant compressed in is condensed and liquefied in the condenser 3 and decompressed by the decompression device 4 to be in a gas-liquid two-phase state.
The load in the showcase such as a refrigerator, a freezer, and a supermarket is cooled by exchanging heat with the outside air in the evaporator 5. The gasified refrigerant flows into the gas-liquid separator 6 from the inlet 6a, and returns to the refrigerant compressors 1 and 2 again through the first suction pipe 7 and the second suction pipe 8, as described above. Repeat cycle. At this time, the first refrigerant compressor 1 and the second refrigerant compressor 2
A small amount of oil contained in the high-temperature and high-pressure gas discharged from the gas passes through the condenser 3, the decompression device 4, and the evaporator 5, and accumulates in the gas-liquid separator 6 (hatched portion in the figure). The oil flows out from the oil outlet 6d of the gas-liquid separator 6, and returns to the refrigerant compressors 1 and 2 through the first oil return pipe 9 and the second oil return pipe 10. here,
The refrigerant compressors 1 and 2 have the same capacity, and the first oil return pipe 9 and the second oil return pipe 10 have the same pipe length so that the oil loss pipes 9 and 10 have the same pressure loss. Becomes Therefore, the oil returning from the gas-liquid separator 6 to each of the refrigerant compressors 1 and 2 is evenly distributed. As described above, the gas-liquid separator 6
Oil return pipes 9 and 10 for connecting oil suction pipes 7 and 8
, The oil can be reliably and evenly returned to each of the refrigerant compressors 1 and 2 regardless of the degree of disturbance of the oil level inside the gas-liquid separator 6. The oil level does not drop and does not lead to a problem that causes oil depletion. The first oil return pipe 9 and the second oil return pipe 10
May be configured such that the lower part of the gas-liquid separator 6 and the suction side of each of the refrigerant compressors 1 and 2 are directly connected in parallel.

Embodiment 2 of the Invention In the second embodiment, in addition to the configuration of the first embodiment, a case will be described in which oil is more reliably returned to each refrigerant compressor. Here, the [Delta] P ₁ the pressure loss in the piping from the oil extraction portion 6d of the gas-liquid separator 6 to the first oil return pipe 9 and the connecting portion 7a of the first suction pipe 7. Moreover, pressure loss to an oil extraction unit 6d and the first refrigerant compressor 1 of the gas-liquid separator 6, i.e., the pressure loss in the first suction pipe 7 and [Delta] P _2. The pressure losses in the second oil return pipe 10 and the second suction pipe 8 are similarly set to ΔP ₃ and ΔP ₄ . Therefore, in the range of ΔP ₁ <ΔP ₂ and ΔP ₃ <ΔP ₄ , in order to maximize the pressure loss in each of the oil return pipes 9 and 10 and improve the oil return, the length of each pipe is set as small as possible. Set larger. From the general formula of hydrodynamics, the relationship between pressure loss and pipe length is expressed by the following formula. ΔP = (１ ／) · λ · (L / d) · v ² Units are ΔP: Pa, λ: anonymous number, L: m, d: m,
V: m / s, and so on. Here, ΔP is a pressure loss, λ is a pipe friction coefficient, L is a pipe length, d is a pipe inner diameter, v
Is the flow velocity. As is clear from the above equation, the pressure loss Δ
P and the pipe length L are proportional. Therefore, the longer the pipe length L, the greater the pressure loss ΔP in the oil return pipe, and the greater the amount of oil return.

Embodiment 3 of the Invention Embodiment 3
Is an example in which each of the oil return pipes 9 and 10 is formed of a capillary tube so as to maximize the pressure loss in the oil return pipe. ΔP ₁ <ΔP ₂ and ΔP ₃ <ΔP
_In order to satisfy the condition of ₄ , the inner diameter d of the pipe must be 0.8 mm
Capillary tubes measuring up to 2 mm are preferred. By applying the above equation, under the same operating conditions, the pressure loss ΔP increases as the pipe inner diameter d decreases. Therefore, even when this capillary tube is used, the oil return is improved.

Embodiment 4 of the Invention Embodiment 4
Is an example in which an orifice is provided in the oil return pipe so as to increase the pressure loss in the oil return pipe. As shown in FIG. 2, the orifice 11 is a disk-shaped metal plate having several round holes. The opening diameter and the numerical aperture of the round hole are set in advance so as to satisfy the conditions of ΔP ₁ <ΔP ₂ and ΔP ₃ <ΔP ₄ . Therefore, as shown in FIG. 3, when the orifice 11 is installed in each of the oil return pipes 9 and 10, a large flow resistance is caused. Therefore,
The pressure loss ΔP before and after the orifice 11 is larger than when there is no orifice 11, and the oil return is improved.

Embodiment 5 of the Invention The fifth embodiment is an example in which two refrigerant compressors having different capacities are mounted in parallel. As shown in FIG. 4, the respective capacities of the third refrigerant compressor 12 and the fourth refrigerant compressor 13 are such that the third refrigerant compressor 12 is X (kW), and the fourth refrigerant compressor 13 is Y (kW). I do.
As described above, the pressure loss is generally expressed by the following equation. ΔP = (1/2) · λ · (L / d) · v ² (1) In the equation (1), ΔP is a pressure loss, λ is a pipe friction coefficient, L is a pipe length, and d is a pipe. The inside diameter, v, is the flow rate. The pipe friction coefficient λ is generally expressed by the following empirical formula. λ = 0.3164 · (v · d / ν) ^-0.25 (2) The unit is ν: Pa · s, and the same applies hereinafter. Here, ν is the kinematic viscosity of the oil flowing in the pipe. By substituting equation (2) into equation (1) and transforming, ΔP = (１ ／) · 0.3164 · (v · d / ν) ^−0.25 · (L / d) · v ² = (1 / 2) · 0.3164 · (L / ν− ^0.25 ) · (1 / d ^1.25 ) · ν ^1.75 · (3) Further, if the flow rate of the oil flowing through the pipe and G, G = a ^{(πd 2/4) · ν} ···· (4). The unit is G: Kg / s, and the same applies hereinafter.

Substituting equation (4) into equation (3) and transforming further, ΔP = (１ ／) · 0.3164 · (L / ν ^−0.25 ) · (1 / d ^1.25 ) · v ^1.75 = (1/2) · 0.3164 · (L / ν -0.25) · (1 / d 1.25) · (G / (πd 2/4)) 1.75 = (1/2) · 0.3164 · (L / ν− ^0.25 · d ^1.25 ) · (1 / (π / 4)) ^1.75 · (G ^1.75 / d ^3.5 ) (5) From equation (5), it can be seen that the oil flow rate G has the following relationship with the pipe length L and the pipe inner diameter d.
(Note) ∝ indicates proportionality. G ｄ d ^{4.75 / 1.75}・ (1 / L) ^{1 / 1.75}・ ・ ・ (6)

From the following, the pipe lengths L of the oil return pipes 9 and 10 are assumed to be the same, ΔP ₁ <ΔP ₂ , and
Within the range where ΔP ₃ <ΔP ₄ , the inner diameter d of each oil return arrangement 9, 10 is determined according to the capacity ratio of the third refrigerant compressor 12 and the fourth refrigerant compressor 13, that is, X: Y. Things. That is, if the inner diameter of the first oil return pipe 9 to the third refrigerant compressor 12 is d ₁ and the inner diameter of the second oil return pipe 10 to the fourth refrigerant compressor 13 is d ₂ , X: Y = D ₁ ^{4.75 / 1.75} : d ₂ The pipe inner diameters d ₁ and d ₂ of the oil return pipes 9 and 10 are determined so that ^{4.75 / 1.75} . Here, the unit is d ₁ : m, d
₂ : m, and so on. With such a structure, even if the capacity of the plurality of refrigerant compressors 12 and 13 is different, the refrigerant compressor 1
The oil can be returned evenly to 2,13.

Embodiment 6 of the Invention Embodiment 6
Is an example in which, when two refrigerant compressors having different capacities are mounted in parallel, the pipe inner diameters of the oil return pipes are the same, and the respective pipe lengths are determined. That is, each oil return pipe 9, 10
Are the same, and within the range of ΔP ₁ <ΔP ₂ and ΔP ₃ <ΔP ₄ , the capacity ratio between the third refrigerant compressor 12 and the fourth refrigerant compressor 13, that is, X:
The pipe length L of each of the oil return pipes 9 and 10 is determined according to Y. If the pipe length of the first oil return pipe 9 to the third refrigerant compressor 12 is L ₁ and the pipe length of the second oil return pipe 10 to the fourth refrigerant compressor 13 is L ₂ , the equation (6) is obtained. From the relation, the pipe lengths L ₁ and L ₂ of the oil return pipes 9 and 10 are determined so that X: Y = (1 / L ₁ ) ^{1 / 1.75} : (1 / L ₂ ) ^{1 / 1.75.} You. Here, the unit is L ₁ : m, L
₂ : m, and so on. With such a structure, even when the capacity of the plurality of refrigerant compressors 12 and 13 is different, each refrigerant compressor 1
The oil can be returned evenly to 2,13.

Embodiment 7 of the Invention Embodiment 7
Is an example in which, when two refrigerant compressors having different capacities are mounted in parallel, the pipe inner diameter and the pipe length of each oil return pipe are determined. That is, ΔP ₁ <ΔP ₂ and ΔP ₃ <Δ
Within range of a P _4, volume ratio of the third refrigerant compressor 12 and the fourth refrigerant compressor 13, i.e. X: determining a pipe length L and the tube inner diameter d of the oil return pipe 9, 10 according to Y Things. From the relationship of Equation (6), X: Y = d 1 4.75 / 1.75 · (1 / L 1) 1 / 1.75: d 2 4.75 / 1.75 · (1 / L 2) to be ^{1 / 1.75,} respectively The length L and the inner diameter d of the oil return pipes 9 and 10 are determined. With such a structure, even when the capacity of the plurality of refrigerant compressors 12 and 13 is different, the refrigerant compressors 12 and 13 are separated from the gas-liquid separator 6.
13 can be evenly returned to the oil.

Embodiment 8 of the Invention FIG. 5 shows a refrigeration apparatus according to Embodiment 8 of the present invention, in which two refrigerant compressors having the same capacity are mounted in parallel. In the figure,
The first refrigerant compressor 1 and the second refrigerant compressor 2 have the same capacity and are provided in parallel. In the middle of the first oil return pipe 9 and the second oil return pipe 10, a first solenoid valve 41 and a second solenoid valve 42 are provided, respectively. In addition, each solenoid valve 41,
The first control unit 43a that controls the opening and closing of the solenoid valves 41, 42
42 is connected by wiring. The first control unit 43a includes, for example, a general-purpose arithmetic processing unit (MPU), a memory storing an arithmetic program and control data (both are not shown), and the like. Each of the control units 43b, 43c, 43d, 43e, 43 exemplified in the embodiments described later.
f and 43g have the same configuration. Here, the refrigerant compressors 1 and 2 have the same capacity, and the first control unit 43a
The solenoid valves 41 and 42 are periodically opened and closed so that the opening times of the solenoid valves 41 and 42 are equal. Accordingly, the solenoid valves 41 and 42 are periodically opened, and the opening times of the solenoid valves 41 and 42 are also set to be the same. Therefore, regardless of the degree of oil level disturbance inside the gas-liquid separator 6, oil is removed. The refrigerant can be reliably and evenly returned to each of the refrigerant compressors 1 and 2, and the oil level in one of the refrigerant compressors 1 and 2 does not drop, and a problem such as oil depletion does not occur. The first oil return pipe 9 and the second oil return pipe 10 are
A configuration in which the lower portion of the gas-liquid separator 6 and the suction sides of the refrigerant compressors 1 and 2 are directly connected in parallel, respectively, may be used.

Embodiment 9 of the Invention FIG. 6 shows a refrigeration apparatus according to Embodiment 9 of the present invention, in which two refrigerant compressors having the same capacity are mounted in parallel. In the figure,
The difference between Embodiment 8 and Embodiment 8 is that each solenoid valve 4
That is, a three-way valve 44 is used instead of the first and second valves 42, and a second control unit 43b that controls switching of the flow path of the three-way valve 44 is used. That is, the three-way valve 44 that switches the oil flow path from the gas-liquid separator 6 to the oil return pipes 9 and 10 at a branch position from the lower part of the gas-liquid separator 6 to the oil return pipes 9 and 10. Is provided. Here, the refrigerant compressors 1 and 2 have the same capacity, and the second control unit 43b controls the oil flow path of the three-way valve 44 so that the communication time to the oil return pipes 9 and 10 is equal. To each oil return pipe 9,1
It is designed to switch to zero. Therefore, the oil flow path of the three-way valve 44 is periodically switched toward the oil return pipes 9 and 10, and the communication time to the oil return pipes 9 and 10 is also equalized. Irrespective of the degree of disturbance of the oil level inside, the oil can be reliably and evenly returned to each of the refrigerant compressors 1 and 2, and the oil level in one of the refrigerant compressors 1 or 2 is reduced, and the oil is depleted. Does not occur. In addition, two solenoid valves 4
The apparatus can be simplified as compared with the case where the first and second elements are used (Embodiment 8).

Embodiment 10 of the Invention FIG. 5 shows a refrigerating apparatus according to Embodiment 10 of the present invention, in which two refrigerant compressors (references in parentheses) having different capacities are mounted in parallel. In the figure, Embodiment 10 of the present invention is different from Embodiment 8 of the present invention in the capacity of the third refrigerant compressor 12 and the fourth refrigerant compressor 13. In addition, each solenoid valve 41,
A third control unit 43 c (symbol in parentheses) that controls opening and closing of 42 is connected to the respective solenoid valves 41 and 42 by wiring. The third control unit 43c opens and closes each of the solenoid valves 41 and 42 so as to have an opening time corresponding to the capacity ratio of each refrigerant compressor. Therefore, the solenoid valves 41, 4 of each oil return pipe 9, 10
2 is opened and closed for an opening time according to the capacity ratio of each of the refrigerant compressors 12 and 13, so that even if the compressor capacities are different, regardless of the degree of disturbance of the oil level inside the gas-liquid separator 6,
The oil can be reliably and evenly returned to each of the refrigerant compressors 12 and 13, and the oil level in one of the refrigerant compressors 12 or 13 does not decrease, and a problem such as oil depletion does not occur.

Embodiment 11 of the Invention FIG. 6 shows a refrigeration apparatus according to Embodiment 11 of the present invention, in which two refrigerant compressors (references in parentheses) having different capacities are mounted in parallel. In the figure, Embodiment 11 of the present invention is different from Embodiment 9 of the present invention in the capacity of the third refrigerant compressor 12 and the fourth refrigerant compressor 13. Further, a fourth control unit 43 d (reference in parentheses) for switching control of the flow path of the three-way valve 44 is connected to the three-way valve 44 by wiring. This fourth control unit 43d
The oil passages of the three-way valve 44 are connected to the respective oil return pipes 9 and 1 such that the communication time is in accordance with the capacity ratio of the refrigerant compressors 12 and 13.
It is designed to switch to zero. Therefore, the oil flow path of the three-way valve 44 is switched toward the oil return pipes 9 and 10 so as to have a communication time corresponding to the capacity ratio of the refrigerant compressors 12 and 13, so that the compressor capacity is different. Even if there is, regardless of how the oil level inside the gas-liquid separator 6 is disordered,
Make sure that each refrigerant compressor 1
2, 13 can be returned to either refrigerant compressor 12
Alternatively, the oil level in the tank 13 does not drop, so that a problem such as oil depletion does not occur. In addition, two solenoid valves 4
The apparatus can be simplified as compared with the case where the first and second elements are used (Embodiment 10).

Embodiment 12 of the Invention FIG. 7 shows a refrigeration apparatus according to Embodiment 12 of the present invention, in which two refrigerant compressors having different capacities are mounted in parallel. In the figure, Embodiment 12 of the present invention is Embodiment 1 of the present invention.
What is different from 0 is that the first oil level detector 4 that is activated when the oil level in the compressor falls below a predetermined level (for example, the level immediately before oil depletion) in the third refrigerant compressor 12 and the fourth refrigerant compressor 13.
Fifth, the second oil level detector 46 is provided. A fifth control unit 43e that controls the opening and closing of the solenoid valves 41 and 42 is connected to the solenoid valves 41 and 42 and the oil level detectors 45 and 46 by wiring. This fifth control unit 4
3e, when each of the oil level detectors 45 and 46 is operated, the first electromagnetic valve 41 or the second electromagnetic valve 42 related to the oil level detector 45 or 46 is opened to allow oil to flow. . That is, when the first oil level detector 45 operates,
When the first solenoid valve 41 is energized to be turned on (open) and the second oil level detector 46 is activated, the first solenoid valve 41 is turned off.
(Closed), the second solenoid valve 42 is energized and turned on (open). Therefore, when the oil level in the refrigerant compressor 12 or 13 falls below a predetermined level, the refrigerant compressor 12
Or 13 is opened to allow the oil to flow by opening the solenoid valve 41 or 42, so that the oil can be reliably transferred to each of the refrigerant compressors 12, 13, regardless of the degree of disturbance of the oil level inside the gas-liquid separator 6.
Can be returned to either refrigerant compressor 12 or 1
There is no possibility that the oil level in 3 will be lowered to cause a problem that oil depletion occurs.

Embodiment 13 of the Invention FIG. 8 shows a refrigeration apparatus according to Embodiment 13 of the present invention, in which two refrigerant compressors having different capacities are mounted in parallel. In the figure, the thirteenth embodiment of the invention is different from the twelfth embodiment in that the three-way valve 44 is used instead of the solenoid valves 41 and 42. Further, a sixth control unit 43f for switching and controlling the flow path of the three-way valve 44 is connected to the three-way valve 44 and the oil level detectors 45 and 46 by wiring. The sixth control unit 43f switches the oil flow path of the three-way valve 44 toward the oil return pipe 9 or 10 associated with the oil level detector 45 or 46 when the oil level detector 45 or 46 is activated. Is to be distributed. That is, when the first oil level detector 45 operates, the three-way valve 44 is energized to switch the oil flow path to the first oil return pipe 9 side, and conversely, the second oil level detector 4
When the valve 6 operates, the oil flow path is switched to the second oil return pipe 10 side. Therefore, when the oil level in the refrigerant compressor 12 or 13 falls below a predetermined level, the oil flow path of the three-way valve 44 is switched toward the oil return pipe 9 or 10 related to the refrigerant compressor 12 or 13. Since the oil is circulated, the oil can be reliably returned to each of the refrigerant compressors 12 and 13 irrespective of the degree of disturbance of the oil level inside the gas-liquid separator 6. The oil level does not drop and does not lead to a problem that causes oil depletion. In addition, the device can be simplified as compared with the case where two electromagnetic valves 41 and 42 are used (Embodiment 12).

Embodiment 14 of the Invention FIG. 7 shows a refrigeration apparatus according to Embodiment 14 of the present invention, in which two refrigerant compressors having different capacities are mounted in parallel. In the figure, Embodiment 14 of the present invention is Embodiment 1 of the present invention.
The difference from the second example is that a seventh control unit 43g (reference in parentheses) having a different function is used instead of the fifth control unit 43e. The seventh control unit 43g is configured to periodically open and close each of the solenoid valves 41 and 42 to cause oil to flow into each of the refrigerant compressors 12 and 13, and to operate the respective oil level detectors 45 and 46 to operate the oil level detectors 45 and 46. Also, the solenoid valves 41 and 42 are opened. That is, the seventh control unit 43g controls each of the solenoid valves 41, 4
2 has a function of opening each of the solenoid valves 41 and 42 in accordance with the earlier one of the periodic timing of opening and the timing of operating the oil level detectors 45 and 46 related to the solenoid valves 41 and 42. doing. For example, even before the next time when any one of the solenoid valves 41 or 42 is periodically opened, if any of the oil level detectors 45 or 46 is activated, the associated refrigerant compressor 12 or 13 will not operate. In order to avoid oil depletion, the seventh control unit 43g forcibly opens the corresponding solenoid valve 41 or 42. Thus, regardless of the degree of disturbance of the oil level inside the gas-liquid separator 6, the oil can be returned to the refrigerant compressors 12, 13 more reliably, and the oil in either the refrigerant compressor 1 or 2 can be returned. A problem that the surface is lowered and oil depletion occurs can be avoided.

In each of the above-described embodiments, an example in which the refrigerant compressor, the oil return pipe, the suction pipe, and the like are provided in two systems has been described. However, the present invention is not limited to this. Needless to say, it can also be applied to.

[0038]

Since the present invention is configured as described above, it has the following effects. That is, in a configuration in which a plurality of refrigerant compressors having the same capacity are provided in parallel, each oil return pipe connected to the suction side of the plurality of refrigerant compressors has the same pipe cross-sectional area and pipe length. Therefore, it is possible to solve the problem that a large amount of oil returns to one refrigerant compressor and no oil returns to another refrigerant compressor, and the oil in the gas-liquid separator is returned equally to each refrigerant compressor. Can be.

Further, the configuration is such that a plurality of refrigerant compressors having the same capacity are provided in parallel, and it is assumed that the pressure loss in the oil return pipe is smaller than the pressure loss in the suction pipe. Since the length of the oil return pipe is set as large as possible, the pressure loss in the oil return pipe can be increased, and the oil return can be further improved.

A plurality of refrigerant compressors having the same capacity are provided in parallel, and it is assumed that the pressure loss in the oil return pipe is within a range in which the pressure loss is smaller than the pressure loss in the suction pipe. Since the oil return pipe is formed of a capillary tube, the pressure loss in the oil return pipe can be increased, and the oil return can be further improved.

Further, a plurality of refrigerant compressors having the same capacity are provided in parallel, and it is assumed that the pressure loss in the oil return pipe is within a range in which the pressure loss is smaller than the pressure loss in the suction pipe. Since the orifice is arranged in the oil return pipe, the pressure loss in the oil return pipe can be increased, and the oil return can be further improved.

Further, the configuration is such that a plurality of refrigerant compressors having different capacities are provided in parallel, and it is assumed that the pressure loss in the oil return pipe is within a range that is smaller than the pressure loss in the suction pipe. As the oil return pipe length is the same and the cross-sectional area in the pipe is set according to the capacity ratio of each refrigerant compressor, so a large amount of oil returns to a certain refrigerant compressor,
The problem that oil does not return to another refrigerant compressor can be solved, and the oil in the gas-liquid separator can be returned equally to each refrigerant compressor.

A plurality of refrigerant compressors having different capacities are provided in parallel, and it is assumed that the pressure loss in the oil return pipe is smaller than the pressure loss in the suction pipe. As the cross-sectional area inside the oil return pipe is the same, and the pipe length is set according to the capacity ratio of each refrigerant compressor, so a large amount of oil returns to one refrigerant compressor, and to another refrigerant compressor The problem that oil does not return can be solved, and the oil in the gas-liquid separator can be returned equally to each refrigerant compressor.

Further, the configuration is such that a plurality of refrigerant compressors having different capacities are provided in parallel, and it is assumed that the pressure loss in the oil return pipe is within a range that is smaller than the pressure loss in the suction pipe. As the length of the oil return pipe and the cross-sectional area inside the pipe are set according to the capacity ratio of each refrigerant compressor, a large amount of oil returns to one refrigerant compressor and no oil returns to another refrigerant compressor. The problem can be solved, and the oil in the gas-liquid separator can be returned to the respective refrigerant compressors evenly.

In a configuration in which a plurality of refrigerant compressors having the same capacity are provided in parallel, the plurality of solenoid valves are periodically opened by the first control unit, and the opening time of each solenoid valve is set to be the same. So that a large amount of oil returns to one refrigerant compressor and does not return to another refrigerant compressor, and the oil in the gas-liquid separator is transferred to each refrigerant compressor. Can be returned evenly.

In a configuration in which a plurality of refrigerant compressors having the same capacity are provided in parallel, the oil flow path of the three-way valve is periodically switched by the second control section toward each oil return pipe.
Since the communication time to each oil return pipe is made equal, it is possible to eliminate the problem that a large amount of oil returns to one refrigerant compressor and no oil returns to another refrigerant compressor. The oil in the vessel can be evenly returned to each refrigerant compressor, and the apparatus can be simplified as compared with the case where an electromagnetic valve is used.

Further, in a configuration in which a plurality of refrigerant compressors having different capacities are provided in parallel, the third control unit is provided in the oil return pipe so as to have an opening time corresponding to the capacity ratio of each refrigerant compressor. Each solenoid valve is opened and closed, so that an amount of oil corresponding to the compressor capacity ratio can be reliably returned to each refrigerant compressor regardless of the degree of oil level disturbance inside the gas-liquid separator. .

Further, in a configuration in which a plurality of refrigerant compressors having different capacities are provided in parallel, the oil flow of the three-way valve is controlled by the fourth control unit so that the communication time becomes in accordance with the capacity ratio of each refrigerant compressor. Because the path is switched to each oil return pipe, regardless of the level of oil level inside the gas-liquid separator,
The amount of oil corresponding to the compressor capacity ratio can be reliably returned to each refrigerant compressor, and the device can be simplified as compared with the case where an electromagnetic valve is used.

In a configuration in which a plurality of refrigerant compressors having different capacities are provided in parallel, when the oil level in the refrigerant compressor falls below a predetermined level, the electromagnetic valve associated with the refrigerant compressor is controlled by the fifth control unit. Is opened to allow the oil to flow, so that the oil can be reliably returned to each of the refrigerant compressors regardless of the level of the oil level inside the gas-liquid separator, and oil depletion can be prevented.

Further, in a configuration in which a plurality of refrigerant compressors having different capacities are provided in parallel, when the oil level in the refrigerant compressor falls below a predetermined level, an oil return associated with the refrigerant compressor is controlled by the sixth control unit. Since the oil flow is switched by switching the oil flow path of the three-way valve toward the pipe, the oil can be reliably returned to each refrigerant compressor regardless of the degree of disturbance of the oil level inside the gas-liquid separator, Oil depletion can be prevented.

Further, in a configuration in which a plurality of refrigerant compressors having different capacities are provided in parallel, it is assumed that each solenoid valve is periodically opened and closed by a seventh control unit. Of the oil level detector associated with each solenoid valve, the solenoid valve is opened according to the earlier timing, so regardless of the degree of oil level disturbance inside the gas-liquid separator, Oil can be more reliably returned to each refrigerant compressor.

[Brief description of the drawings]

FIG. 1 is a refrigerant piping diagram showing a refrigeration apparatus according to Embodiments 1 to 3 of the present invention.

FIG. 2 is a plan view of an orifice according to Embodiment 4 of the present invention.

FIG. 3 is a configuration diagram showing a state in which an orifice is mounted in an oil return pipe according to Embodiment 4 of the present invention.

FIG. 4 is a refrigerant piping diagram showing a refrigeration apparatus according to Embodiments 5 to 7 of the present invention.

FIG. 5 is a diagram showing an embodiment 8 or 1 of the present invention;
It is a refrigerant | coolant piping system diagram which shows the refrigerating apparatus concerning No. 0.

FIG. 6 is a view illustrating a ninth embodiment or a first embodiment of the present invention;
It is a refrigerant | coolant piping system diagram which shows the refrigerating apparatus concerning No. 1.

FIG. 7 is a refrigerant piping diagram showing a refrigeration apparatus according to Embodiment 12 or 14 of the present invention.

FIG. 8 is a refrigerant piping system diagram showing a refrigeration apparatus according to Embodiment 13 of the present invention.

FIG. 9 is a refrigerant piping system diagram showing a conventional refrigeration apparatus.

FIG. 10 is a sectional view showing a gas-liquid separator of a conventional refrigeration apparatus.

[Explanation of symbols]

Reference Signs List 1 first refrigerant compressor, 2 second refrigerant compressor, 3 condenser, 4 decompression device, 5 evaporator, 6 gas-liquid separator, 6b
Outlet part, 6c outlet part, 6d oil take-out part, 7 first suction pipe, 7a connection section, 8 second suction pipe, 8a connection section, 9 first oil return pipe, 10 second oil return pipe, 1
REFERENCE SIGNS LIST 1 orifice, 12 third refrigerant compressor, 13 fourth refrigerant compressor, 41 first solenoid valve, 42 second solenoid valve, 43
a first control unit, 43b second control unit, 43c third control unit, 43d fourth control unit, 43e fifth control unit, 43
f Sixth control unit, 43g Seventh control unit, 44 Three-way valve,
45 First oil level detector, 46 Second oil level detector.

Claims (14)

[Claims] 1. A plurality of refrigerant compressors, condensers, decompression devices, evaporators, gas-liquid separators, etc., which are provided in parallel with the same capacity and are sequentially arranged in a circuit form, and an upper part of the gas-liquid separator. And a plurality of suction pipes connecting the suction sides of the plurality of refrigerant compressors in parallel, and a plurality of suction pipes connecting the lower side of the gas-liquid separator and the suction sides of the plurality of refrigerant compressors in parallel, respectively. Wherein the plurality of oil return pipes have the same cross-sectional area and the same pipe length set for each of the plurality of oil return pipes. 2. A plurality of refrigerant compressors, condensers, decompression devices, evaporators, gas-liquid separators and the like, which are provided in parallel with the same capacity, are sequentially arranged in a circuit form, and the upper part of the gas-liquid separator is provided. And a plurality of suction pipes connecting the suction sides of the plurality of refrigerant compressors in parallel, and a plurality of suction pipes connecting the lower side of the gas-liquid separator and the suction sides of the plurality of refrigerant compressors in parallel, respectively. In the refrigerating apparatus including the oil return pipe, the plurality of oil return pipes have a pressure loss in each of the oil return pipes higher than a pressure loss in the suction pipe connected to the same refrigerant compressor. A refrigeration apparatus characterized in that it is configured to have a large pipe length set within a range where the length is reduced. 3. A plurality of refrigerant compressors, condensers, decompression devices, evaporators, gas-liquid separators and the like, which are provided in parallel with the same capacity, are sequentially arranged in a circuit shape, and an upper part of the gas-liquid separator is provided. And a plurality of suction pipes connecting the suction sides of the plurality of refrigerant compressors in parallel, and a plurality of suction pipes connecting the lower side of the gas-liquid separator and the suction sides of the plurality of refrigerant compressors in parallel, respectively. In the refrigerating apparatus including the oil return pipe, the plurality of oil return pipes have a pressure loss in each of the oil return pipes higher than a pressure loss in the suction pipe connected to the same refrigerant compressor. A refrigeration apparatus comprising a capillary tube that satisfies a condition for reduction in size. 4. A plurality of refrigerant compressors, condensers, decompression devices, evaporators, gas-liquid separators, etc., which are provided in parallel with the same capacity, are sequentially arranged in a circuit form, and the upper part of the gas-liquid separator is provided. And a plurality of suction pipes connecting the suction sides of the plurality of refrigerant compressors in parallel, and a plurality of suction pipes connecting the lower side of the gas-liquid separator and the suction sides of the plurality of refrigerant compressors in parallel, respectively. In the refrigerating apparatus including the oil return pipe, in the plurality of oil return pipes, the pressure loss in each of the oil return pipes is smaller than the pressure loss in the suction pipe connected to the same refrigerant compressor. A refrigerating apparatus, wherein an orifice that satisfies the condition of reducing the size is also provided. 5. A plurality of refrigerant compressors, condensers, decompression devices, evaporators, gas-liquid separators and the like, which are provided in parallel with different capacities, are sequentially arranged in a circuit form, and the upper part of the gas-liquid separator and A plurality of suction pipes for connecting the suction sides of the plurality of refrigerant compressors in parallel, and a plurality of suction pipes for connecting the lower side of the gas-liquid separator and the suction sides of the plurality of refrigerant compressors in parallel. In the refrigerating apparatus including the oil return pipe, the plurality of oil return pipes are respectively set to the same pipe length, and the pressure losses in the respective oil return pipes are connected to the same refrigerant compressor. A refrigeration apparatus characterized in that the refrigeration apparatus is set within a range where the pressure loss is smaller than the pressure loss in the suction pipe, and is set to a cross-sectional area in the pipe corresponding to a capacity ratio of the plurality of refrigerant compressors. 6. A plurality of refrigerant compressors, condensers, decompression devices, evaporators, gas-liquid separators and the like, which are provided in parallel with different capacities, are sequentially arranged in a circuit form. A plurality of suction pipes for connecting the suction sides of the plurality of refrigerant compressors in parallel, and a plurality of suction pipes for connecting the lower side of the gas-liquid separator and the suction sides of the plurality of refrigerant compressors in parallel. In the refrigerating apparatus including the oil return pipe, the plurality of oil return pipes are each set to have the same cross-sectional area in the pipe, and the pressure loss in each of the oil return pipes is connected to the same refrigerant compressor. A refrigerating apparatus characterized by being set within a range where the pressure loss is smaller than the pressure loss in the suction pipe and a pipe length corresponding to a capacity ratio of the plurality of refrigerant compressors. 7. A plurality of refrigerant compressors, condensers, decompression devices, evaporators, gas-liquid separators, etc., which are provided in parallel with different capacities, are sequentially arranged in a circuit form. A plurality of suction pipes for connecting the suction sides of the plurality of refrigerant compressors in parallel, and a plurality of suction pipes for connecting the lower side of the gas-liquid separator and the suction sides of the plurality of refrigerant compressors in parallel. In the refrigerating apparatus including the oil return pipe, the plurality of oil return pipes have a pressure loss in the respective oil return pipes smaller than a pressure loss in the suction pipe connected to the same refrigerant compressor. A refrigeration apparatus characterized in that the refrigeration apparatus is configured to be set within a certain range and to have a cross-sectional area in a pipe and a pipe length corresponding to a capacity ratio of the plurality of refrigerant compressors. 8. A plurality of refrigerant compressors, condensers, decompression devices, evaporators, gas-liquid separators, etc., which are provided in parallel with the same capacity, are sequentially arranged in a circuit form, and the upper part of the gas-liquid separator is provided. And a plurality of suction pipes connecting the suction sides of the plurality of refrigerant compressors in parallel, and a plurality of suction pipes connecting the lower side of the gas-liquid separator and the suction sides of the plurality of refrigerant compressors in parallel, respectively. In the refrigerating apparatus provided with the oil return pipe, the plurality of solenoid valves provided for each of the plurality of oil return pipes, and the respective solenoid valves are periodically opened and closed so that the opening times of the respective solenoid valves are equal. A refrigeration apparatus comprising: 9. A plurality of refrigerant compressors, condensers, decompression devices, evaporators, gas-liquid separators and the like, which are provided in parallel with the same capacity, are sequentially arranged in a circuit form, and the upper part of the gas-liquid separator is provided. And a plurality of suction pipes connecting the suction sides of the plurality of refrigerant compressors in parallel, and a plurality of suction pipes connecting the lower side of the gas-liquid separator and the suction sides of the plurality of refrigerant compressors in parallel, respectively. In the refrigerating apparatus provided with an oil return pipe, an oil flow path from the gas-liquid separator is provided at a branch position from a lower portion of the gas-liquid separator to the plurality of oil return pipes with respect to each oil return pipe. A three-way valve that switches to be communicable, and a second control unit that periodically switches the oil flow path of the three-way valve toward each of the oil return pipes so as to equalize the communication time to each of the oil return pipes. A refrigeration device characterized by comprising: 10. A plurality of refrigerant compressors, condensers, decompression devices, evaporators, gas-liquid separators and the like, which are provided in parallel with different capacities, are sequentially arranged in a circuit shape, and the upper part of the gas-liquid separator and A plurality of suction pipes for connecting the suction sides of the plurality of refrigerant compressors in parallel, and a plurality of suction pipes for connecting the lower side of the gas-liquid separator and the suction sides of the plurality of refrigerant compressors in parallel. In a refrigerating apparatus having an oil return pipe,
A plurality of solenoid valves provided for each of the plurality of oil return pipes,
A refrigeration apparatus comprising: a third control unit that opens and closes each solenoid valve so that the opening time is in accordance with the capacity ratio of each refrigerant compressor. 11. A plurality of refrigerant compressors, condensers, decompression devices, evaporators, gas-liquid separators, and the like, which are provided in parallel with different capacities, are sequentially arranged in a circuit shape, and the upper part of the gas-liquid separator and A plurality of suction pipes for connecting the suction sides of the plurality of refrigerant compressors in parallel, and a plurality of suction pipes for connecting the lower side of the gas-liquid separator and the suction sides of the plurality of refrigerant compressors in parallel. In a refrigerating apparatus having an oil return pipe,
A three-way valve that is provided at a branch position from the lower part of the gas-liquid separator to the plurality of oil return pipes and that switches an oil flow path from the gas-liquid separator to be communicable with each oil return pipe; A refrigerating apparatus comprising: a fourth control unit that switches an oil flow path of the three-way valve toward each of the oil return pipes so that a communication time according to a capacity ratio of the three-way valve is established. 12. A plurality of refrigerant compressors, condensers, decompression devices, evaporators, gas-liquid separators and the like, which are provided in parallel with different capacities, are sequentially arranged in a circuit form. A plurality of suction pipes for connecting the suction sides of the plurality of refrigerant compressors in parallel, and a plurality of suction pipes for connecting the lower side of the gas-liquid separator and the suction sides of the plurality of refrigerant compressors in parallel. In a refrigerating apparatus having an oil return pipe,
A plurality of solenoid valves provided for each of the plurality of oil return pipes,
A plurality of oil level detectors provided in each of the plurality of refrigerant compressors and operating when an oil level in the compressor falls below a predetermined level; and an electromagnetic wave associated with the oil level detector when the oil level detector operates. A refrigeration apparatus comprising: a fifth control unit that opens a valve. 13. A plurality of refrigerant compressors, condensers, decompression devices, evaporators, gas-liquid separators, etc., which are provided in parallel with different capacities, are sequentially arranged in a circuit shape, and the upper part of said gas-liquid separator is provided. A plurality of suction pipes for connecting the suction sides of the plurality of refrigerant compressors in parallel, and a plurality of suction pipes for connecting the lower side of the gas-liquid separator and the suction sides of the plurality of refrigerant compressors in parallel. In a refrigerating apparatus having an oil return pipe,
A three-way valve provided at a branch position from a lower portion of the gas-liquid separator to the plurality of oil return pipes to switch an oil flow path from the gas-liquid separator to be communicable with each oil return pipe, and the plurality of refrigerants; A plurality of oil level detectors provided in the compressor and operating when the oil level in the compressor falls below a predetermined level, and directed to an oil return pipe associated with the oil level detector when the oil level detector operates. A refrigeration apparatus comprising: a sixth control unit that switches an oil flow path of the three-way valve. 14. A plurality of refrigerant compressors, condensers, decompression devices, evaporators, gas-liquid separators and the like, which are provided in parallel with different capacities, are sequentially arranged in a circuit shape, and the upper part of the gas-liquid separator and A plurality of suction pipes for connecting the suction sides of the plurality of refrigerant compressors in parallel, and a plurality of suction pipes for connecting the lower side of the gas-liquid separator and the suction sides of the plurality of refrigerant compressors in parallel. In a refrigerating apparatus having an oil return pipe,
A plurality of solenoid valves provided for each of the plurality of oil return pipes,
Each of the plurality of refrigerant compressors is provided with a plurality of oil level detectors that operate when the oil level in the compressor falls below a predetermined level, and each solenoid valve is periodically opened and closed, and each of the solenoid valves is opened. Refrigeration characterized by comprising a seventh control unit that opens each of the solenoid valves in accordance with an earlier one of a periodic timing and a timing at which an oil level detector associated with each of the solenoid valves operates. apparatus.