JP4033248B2 - Refrigeration equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a refrigeration apparatus used in a supermarket showcase, refrigerator, freezer, and the like.
[0002]
[Prior art]
FIG. 9 is a refrigerant piping diagram showing a conventional refrigeration apparatus in which two refrigerant compressors are mounted in parallel, and FIG. 10 is a cross-sectional view showing a gas-liquid separator of the conventional refrigeration apparatus.
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, U-shaped suction pipes 29, 30 provided with an inlet pipe 36 and oil return holes 31, 32 are arranged and communicated with the suction pipes 7, 8.
[0003]
Next, the operation will be described. The high-temperature and high-pressure refrigerant compressed by the refrigerant compressors 1 and 2 is condensed by the condenser 8 and liquefied. The liquid refrigerant passes through the refrigerant pipe (not labeled) and is decompressed by the decompression device 4 to be in a gas-liquid two-phase state. Cool down. The example place that exchanges heat 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 passes through the circuit and accumulates in the gas-liquid separator 6. The refrigerant is sucked from the openings 29a and 30a at the tips of the U-shaped suction pipes 29 and 30 in the gas-liquid separator 6 and returns to the refrigerant compressors 1 and 2 through the suction pipes 7 and 8, respectively. Repeat the cycle.
On the other hand, the oil accumulated in the gas-liquid separator 6 is sucked up from the lower oil return holes 31 and 32 and returned to the refrigerant compressors 1 and 2 through the suction pipes 7 and 8, respectively. 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 how the oil level in the gas-liquid separator 6 is turbulent, one may be higher than the oil return hole and the other may be higher than the oil return hole. The amount of oil in one refrigerant compressor increases, and the amount of oil in the refrigerant compressor that does not reach the oil return hole decreases.
[0004]
[Problems to be solved by the invention]
As described above, in the conventional refrigeration apparatus, the amount of oil sucked up from the oil return hole of each U-shaped suction pipe may not be uniform depending on the position of the oil return hole and the oil level in the vessel. Therefore, the oil level in the refrigerant compressor having the smaller amount of oil sucked down decreases, and if such a state continues for a long time, there is a possibility that the compressor may be broken due to oil exhaustion.
[0005]
The present invention has been made to solve the above problems, and the oil accumulated in the gas-liquid separator is uniformly returned to each refrigerant compressor without being affected by the disturbance of the oil level. And it aims at provision of the freezing apparatus which does not produce the malfunction by the oil level fall of a compressor.
[0006]
[Means for Solving the Problems]
  In order to achieve the above object, a refrigeration apparatus according to the present invention comprises:A plurality of refrigerant compressors, condensers, pressure reducing devices, evaporators, gas-liquid separators, etc., which are provided in parallel with different capacities are sequentially arranged in a circuit, and the upper part of the gas-liquid separator and a plurality of refrigerant compressors A refrigeration apparatus comprising a plurality of suction pipes that connect the suction side in parallel, and a plurality of oil return pipes that connect the lower part of the gas-liquid separator and the suction sides of the plurality of refrigerant compressors in parallel, respectively. A plurality of solenoid valves provided for each of a plurality of oil return pipes, a plurality of oil level detectors each provided in a plurality of refrigerant compressors and operating when the oil level in the compressor falls below a predetermined level, The seventh is to open and close each solenoid valve according to the earliest timing among the periodic timing when each solenoid valve is opened and the timing when the oil level detector associated with each solenoid valve is activated. And a control unit. .
[0007]
  Also, comprising a plurality of solenoid valves provided for each of the plurality of oil return pipes, and a third control unit for opening and closing each solenoid valve so as to have an opening time according to the capacity ratio of each refrigerant compressor Is what.
[0008]
  Further, a three-way valve provided at a branch position from the lower part of the gas-liquid separator to the plurality of oil return pipes for switching the oil flow path from the gas-liquid separator to be communicable with each oil return pipe, and each refrigerant compressor And a fourth control unit that switches the oil flow path of the three-way valve toward each oil return pipe so as to have a communication time according to the capacity ratio.
[0009]
  And a plurality of solenoid valves provided for each of the plurality of oil return pipes, a plurality of oil level detectors respectively provided in the plurality of refrigerant compressors and operating when the oil level in the compressor falls below a predetermined level, And a fifth control unit that opens a solenoid valve related to the oil level detector when the surface detector is activated.
[0010]
  Further, a three-way valve provided at a branch position from the lower part of the gas-liquid separator to the plurality of oil return pipes and switching the oil flow path from the gas-liquid separator to each oil return pipe, and a plurality of refrigerant compressors A plurality of oil level detectors that operate when the oil level in the compressor falls below a predetermined level, and a three-way valve toward the oil return pipe associated with the oil level detector when the oil level detector operates. And a sixth control section for switching the oil flow path.
[0011]
  A plurality of refrigerant compressors, condensers, pressure reducing devices, evaporators, gas-liquid separators, etc., which have the same capacity and are arranged in parallel, are sequentially arranged in a circuit, and the upper part of the gas-liquid separator and a plurality of refrigerant compressors Refrigeration provided with a plurality of suction pipes connected in parallel with each other and a plurality of oil return pipes connected respectively in parallel with the lower part of the gas-liquid separator and the suction sides of the plurality of refrigerant compressors In the apparatus, a plurality of solenoid valves provided for each of a plurality of oil return pipes, a plurality of oil level detectors each provided in a plurality of refrigerant compressors and operating when the oil level in the compressor falls below a predetermined level, Each solenoid valve is opened and closed periodically, and each solenoid valve is opened according to the earlier timing among the periodic timing when each solenoid valve is opened and the timing when the oil level detector associated with each solenoid valve is activated. And a seventh control unit. .
[0012]
  In addition, it comprises 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 as to equalize the open time of each solenoid valve. It is what. A three-way valve provided at a branch position from the lower part of the gas-liquid separator to the plurality of oil return pipes to switch the oil flow path from the gas-liquid separator to communicate with each oil return pipe, and to 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 as to equalize the communication time.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
  Continuing with this inventionReference examples andEmbodiments will be described with reference to the drawings.
Reference example 1.
  FIG. 1 illustrates the present invention.Reference example 1Shows a case where two refrigerant compressors having the same capacity are mounted in parallel.
  In the figure, 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, 5 is an evaporator, 6 is a gas-liquid separator, 7 is a first suction pipe connecting the outlet portion 6c of the upper portion of the gas-liquid separator 6 and the suction side of the first refrigerant compressor 1, and 8 is an outlet portion 6b of the upper portion of the gas-liquid separator 6. A second suction pipe for connecting the suction side of the second refrigerant compressor 2, 9 is a first oil return pipe that is connected to the connection portion 7 a of the first suction pipe 7 through the oil take-out portion 6 d below the gas-liquid separator 6. Reference numeral 10 denotes 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 have the same in-pipe cross-sectional area and pipe length.
[0021]
  thisReference exampleThe refrigeration apparatus 1 is configured as described above. Next, the operation of this refrigeration apparatus will be described.
  First, the high-temperature and high-pressure refrigerant compressed by the first refrigerant compressor 1 and the second refrigerant compressor 2 is condensed and liquefied by the condenser 3, and is decompressed by the decompression device 4 to be in a gas-liquid two-phase state, evaporating. Heat is exchanged with outside air in the vessel 5 to cool the load in the showcase of a refrigerator, freezer, supermarket, or the like. The gasified refrigerant flows into the gas-liquid separator 6 from the inlet 6a, and then 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, a small amount of oil contained in the high-temperature and high-pressure gas discharged from the first refrigerant compressor 1 and the second refrigerant compressor 2 passes through the condenser 3, the decompression device 4 and the evaporator 5, and passes through the gas-liquid separator 6. Accumulate inside (shaded area in the figure). The oil flows out from the oil take-out part 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 pressures of the oil return pipes 9 and 10 are equalized by making the lengths of the first oil return pipe 9 and the second oil return pipe 10 the same. The loss is the same. Accordingly, the oil returning from the gas-liquid separator 6 to the refrigerant compressors 1 and 2 is evenly distributed.
  As described above, since the oil return pipes 9 and 10 that connect the gas-liquid separator 6 and the suction pipes 7 and 8 have the above structure, the oil level inside the gas-liquid separator 6 is affected by the turbulence. Therefore, the oil can be reliably and evenly returned to the refrigerant compressors 1 and 2, and the oil level in one of the refrigerant compressors is not lowered, and there is no problem that oil is exhausted.
  The first oil return pipe 9 and the second oil return pipe 10 may be configured to directly connect the lower part of the gas-liquid separator 6 and the suction side of each refrigerant compressor 1, 2 in parallel. I do not care.
[0022]
Reference example 2.
  thisReference example 2ThenReference example 1In addition to this configuration, the oil is more reliably returned to each refrigerant compressor.
  Here, the pressure loss in the pipe from the oil take-out part 6d of the gas-liquid separator 6 to the connection part 7a of the first oil return pipe 9 and the first suction pipe 7 is represented by ΔP1. Further, the pressure loss between the oil take-out part 6d of the gas-liquid separator 6 and the first refrigerant compressor 1, that is, the pressure loss in the first suction pipe 7 is denoted by ΔP2. Similarly, the pressure loss in the second oil return pipe 10 and the second suction pipe 8 is set to ΔP3 and ΔP4.
  Therefore, ΔP₁<ΔP₂And ΔP_Three<ΔP_FourIn order to improve the oil return by increasing the pressure loss in the oil return pipes 9 and 10 as much as possible, the length of each pipe is set as large as possible.
  From the general formula of hydrodynamics, the relationship between pressure loss and pipe length is expressed by the following formula.
  ΔP = (1/2) · λ · (L / d) · v²
  The 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, and v is a flow velocity.
  As is clear from the above equation, the pressure loss ΔP and the pipe length L are proportional. Therefore, the longer the pipe length L, the larger the pressure loss ΔP in the oil return pipe, and the oil return amount can be increased.
[0023]
Reference example 3.
  thisReference example 3Is an example in which each of the oil return pipes 9 and 10 is configured with a capillary tube so as to maximize the pressure loss in the oil return pipe.
  ΔP₁<ΔP₂And ΔP_Three<ΔP_FourIn order to satisfy the following condition, a capillary tube having a tube inner diameter d of 0.8 mm to 2 mm is preferable. Applying the above equation, under the same operating conditions, the pressure loss ΔP increases as the pipe inner diameter d decreases. Therefore, oil return is improved even when this capillary tube is used.
[0024]
Reference example 4.
  Reference Example 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 disc-shaped metal plate having a number of round holes. The opening diameter and numerical aperture of the round hole are ΔP₁<ΔP₂And ΔP_Three<ΔP_FourIs set in advance so as to satisfy the following condition.
  Therefore, as shown in FIG. 3, when the orifice 11 is mounted in each of the oil return pipes 9 and 10, a large resistance to the flow is obtained. Therefore, the pressure loss ΔP before and after the orifice 11 becomes larger than that without the orifice 11 and the oil return is improved.
[0025]
Reference Example 5.
  thisReference Example 5Is an example in which two refrigerant compressors with different capacities are mounted in parallel.
  As shown in FIG. 4, the third refrigerant compressor 12 and the fourth refrigerant compressor 13 have a capacity of X (kW) for the third refrigerant compressor 12 and Y (kW) for the fourth refrigerant compressor 13, respectively. To do.
  As described above, the pressure loss is generally expressed by the following equation.
  ΔP = (1/2) · λ · (L / d) · v²(1)
  In the equation (1), ΔP is a pressure loss, λ is a pipe friction coefficient, L is a pipe length, d is a pipe inner diameter, and v is a flow velocity.
  Further, 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 so on.
  Where ν is the kinematic viscosity of the oil flowing in the pipe. Substituting Equation (2) into Equation (1) for transformation,
    ΔP = (1/2) · 0.3164 ·
              (V · d / ν)^-0.25・ (L / d) ・ v²
        = (1/2) .0.3164.
              (L / ν^-0.25) ・ (1 / d^1.25) ・ Ν^1.75  (3)
become.
  If the flow rate of oil flowing through the pipe is G,
  G = (πd²/ 4) ・ ν ・ ・ ・ ・ (4)
It becomes.
  The unit is G: Kg / s, and so on.
[0026]
  Substituting equation (4) into equation (3) and further transforming,
  ΔP = (1/2) · 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 / (πd²/ 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 respect to the pipe length L and the pipe inner diameter d. (Note) ∝ represents proportionality.
  G ｄ d^{4.75 / 1.75}・ (1 / L)^{1 / 1.75}... (6)
[0027]
  From the following, the oil return pipes 9 and 10 have the same pipe length L, and ΔP₁<ΔP₂And ΔP_Three<ΔP_FourIn this range, the pipe inner diameter d of each of the oil return arrangements 9 and 10 is determined according to the capacity ratio of the third refrigerant compressor 12 and the fourth refrigerant compressor 13, that is, X: Y.
  That is, the pipe inner diameter of the first oil return pipe 9 to the third refrigerant compressor 12 is d₁The inner diameter of the second oil return pipe 10 to the fourth refrigerant compressor 13 is d₂given that,
  X: Y = d₁ ^{4.75 / 1.75}: D₂ ^{4.75 / 1.75}
The inner diameter d of each of the oil return pipes 9 and 10 is₁, D₂Is determined.
  Here, the unit is d₁: M, d₂: M, and so on.
  By adopting such a structure, even if the capacities of the plurality of refrigerant compressors 12 and 13 are different, oil can be evenly returned from the gas-liquid separator 6 to the refrigerant compressors 12 and 13.
[0028]
Reference Example 6.
  thisReference Example 6Is 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 pipe lengths thereof are determined.
  That is, the oil return pipes 9 and 10 have the same pipe inner diameter d, and ΔP₁<ΔP₂And ΔP_Three<ΔP_FourIn this range, the pipe length L of each of the oil return pipes 9 and 10 is determined according to the capacity ratio of the third refrigerant compressor 12 and the fourth refrigerant compressor 13, that is, X: Y.
  The pipe length of the first oil return pipe 9 to the third refrigerant compressor 12 is L1, and the pipe length of the second oil return pipe 10 to the fourth refrigerant compressor 13 is L.₂Then, from the relationship of equation (6),
  X: Y = (1 / L₁)^{1 / 1.75}: (1 / L₂)^{1 / 1.75}
The pipe length L of each of the oil return pipes 9 and 10 is₁, L₂Is determined.
  Here, the unit is L₁: M, L₂: M, and so on.
  By adopting such a structure, even when the capacities of the plurality of refrigerant compressors 12 and 13 are different, oil can be evenly returned from the gas-liquid separator 6 to the refrigerant compressors 12 and 13.
[0029]
Reference Example 7.
  thisReference Example 7Is an example in which the pipe inner diameter and the pipe length of each oil return pipe are respectively determined when two refrigerant compressors having different capacities are mounted in parallel.
  That is, ΔP₁<ΔP₂And ΔP_Three<ΔP_FourIn this range, the pipe length L and the pipe inner diameter d of each of the oil return pipes 9 and 10 are determined according to the capacity ratio of the third refrigerant compressor 12 and the fourth refrigerant compressor 13, that is, X: Y. is there.
  From the relationship of equation (6),
  X: Y = d₁ ^{4.75 / 1.75}・ (1 / L₁)^{1 / 1.75}
                      : D₂ ^{4.75 / 1.75}・ (1 / L₂)^{1 / 1.75}
Thus, the pipe length L and the pipe inner diameter d of each of the oil return pipes 9 and 10 are determined.
  By adopting such a structure, even when the capacities of the plurality of refrigerant compressors 12 and 13 are different, oil can be evenly returned from the gas-liquid separator 6 to the refrigerant compressors 12 and 13.
[0030]
BEST MODE FOR CARRYING OUT THE INVENTION1.
  FIG. 5 shows an embodiment of the present invention.1Shows a case where 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. A first solenoid valve 41 and a second solenoid valve 42 are provided in the middle of the first oil return pipe 9 and the second oil return pipe 10, respectively. A first control unit 43 a that controls opening and closing of the electromagnetic valves 41 and 42 is connected to the electromagnetic valves 41 and 42 by wiring. The first control unit 43a includes, for example, a general-purpose arithmetic processing unit (MPU), a memory (not shown) that stores arithmetic programs and control data, and the like. The control units 43b, 43c, 43d, 43e, 43f, and 43g exemplified in the embodiments described later have the same configuration.
  Here, the refrigerant compressors 1 and 2 have the same capacity, and the first controller 43a periodically sets the electromagnetic valves 41 and 42 so that the opening times of the electromagnetic valves 41 and 42 are equal. It is designed to open and close.
  Accordingly, the electromagnetic valves 41 and 42 are periodically opened, and the opening times of the electromagnetic valves 41 and 42 are also made the same, so that the oil is discharged regardless of the turbulence of the oil level inside the gas-liquid separator 6. The refrigerant compressors 1 and 2 can be surely and evenly returned to each other, so that the oil level in one of the refrigerant compressors 1 or 2 is not lowered, and there is no problem of causing oil exhaustion.
  The first oil return pipe 9 and the second oil return pipe 10 may be configured to directly connect the lower part of the gas-liquid separator 6 and the suction side of each refrigerant compressor 1, 2 in parallel. I do not care.
[0031]
BEST MODE FOR CARRYING OUT THE INVENTION2.
  FIG. 6 shows an embodiment of the present invention.2Shows a case where two refrigerant compressors having the same capacity are mounted in parallel.
  In the figure, the embodiment of the invention1The difference from the configuration is that a three-way valve 44 is used instead of the electromagnetic valves 41 and 42 and a second control unit 43b that switches and controls 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 so as to communicate with the oil return pipes 9 and 10 at the 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 has an oil flow path of the three-way valve 44 so that the communication times to the oil return pipes 9 and 10 are equal. Are periodically switched toward the oil return pipes 9 and 10.
  Accordingly, 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. Regardless of the turbulence of the internal oil level, the oil can be reliably and evenly returned to the refrigerant compressors 1 and 2, and the oil level in either of the refrigerant compressors 1 or 2 is lowered, resulting in oil depletion. This will not lead to a problem that causes In addition, when two solenoid valves 41 and 42 are used (the embodiment)1Compared with), the apparatus can be simplified.
[0032]
BEST MODE FOR CARRYING OUT THE INVENTION3.
  FIG. 5 shows an embodiment of the present invention.3Shows a case where two refrigerant compressors (in parentheses) having different capacities are mounted in parallel.
  In the figure, the embodiment of the invention3Is an embodiment of the invention1Compared with the third refrigerant compressor 12, the capacity of the fourth refrigerant compressor 13 is different from that of the fourth refrigerant compressor 13. In addition, a third control unit 43c (indicated in parentheses) that controls the opening and closing of the electromagnetic valves 41 and 42 is connected to the electromagnetic valves 41 and 42 by wiring. The third control unit 43c opens and closes the electromagnetic valves 41 and 42 so as to have an opening time according to the capacity ratio of the refrigerant compressors.
  Accordingly, the solenoid valves 41 and 42 of the oil return pipes 9 and 10 are opened and closed in an open time corresponding to the capacity ratio of the refrigerant compressors 12 and 13, so that even if the compressor capacity is different, the gas-liquid Regardless of the turbulence of the oil level inside the separator 6, the oil can be reliably and evenly returned to the refrigerant compressors 12 and 13, and the oil level in one of the refrigerant compressors 12 or 13 decreases. It does not lead to problems such as oil exhaustion.
[0033]
BEST MODE FOR CARRYING OUT THE INVENTION4.
  FIG. 6 shows an embodiment of the present invention.4Shows a case where two refrigerant compressors (in parentheses) having different capacities are mounted in parallel.
  In the figure, the embodiment of the invention4Is an embodiment of the invention2Compared with the third refrigerant compressor 12, the capacity of the fourth refrigerant compressor 13 is different from that of the fourth refrigerant compressor 13. In addition, a fourth control unit 43 d (indicated in parentheses) that switches and controls the flow path of the three-way valve 44 is wired to the three-way valve 44. The fourth control unit 43d switches the oil flow path of the three-way valve 44 toward the oil return pipes 9 and 10 so that the communication time according to the capacity ratio of the refrigerant compressors 12 and 13 is reached. Yes.
  Accordingly, the oil flow path of the three-way valve 44 is switched toward the oil return pipes 9 and 10 so that the communication time according to the capacity ratio of the refrigerant compressors 12 and 13 is reached. Even if it exists, the amount of oil according to the compressor capacity ratio can be surely returned to the refrigerant compressors 12 and 13 regardless of the turbulence of the oil level inside the gas-liquid separator 6, and either refrigerant There is no possibility that the oil level in the compressor 12 or 13 is lowered and the oil is exhausted. In addition, when two solenoid valves 41 and 42 are used (the embodiment)3Compared with), the apparatus can be simplified.
[0034]
BEST MODE FOR CARRYING OUT THE INVENTION5.
  FIG. 7 shows an embodiment of the present invention.5Shows a case where two refrigerant compressors with different capacities are mounted in parallel.
  In the figure, an embodiment of the present invention5Is an embodiment of the invention3Is different from the first oil level detector 45 that operates when the oil level in the compressor falls below a predetermined level (for example, the level just before oil exhaustion) in the third refrigerant compressor 12 and the fourth refrigerant compressor 13, The second oil level detector 46 is provided. The fifth control unit 43e that controls opening and closing of the electromagnetic valves 41 and 42 is connected to the electromagnetic valves 41 and 42 and the oil level detectors 45 and 46 by wiring. When the oil level detectors 45 and 46 are activated, the fifth control unit 43e opens the first electromagnetic valve 41 or the second electromagnetic valve 42 related to the oil level detector 45 or 46 and distributes the oil. It is like that. That is, when the first oil level detector 45 is activated, the first electromagnetic valve 41 is energized and turned on (opened). Conversely, when the second oil level detector 46 is activated, the first electromagnetic valve 41 is turned off (closed). The second solenoid valve 42 is energized and turned on (opened).
  Therefore, when the oil level in the refrigerant compressor 12 or 13 falls below a predetermined level, the electromagnetic valve 41 or 42 associated with the refrigerant compressor 12 or 13 is opened to circulate the oil. Regardless of the turbulence of the oil level, the oil can be reliably returned to the refrigerant compressors 12 and 13, and the oil level in one of the refrigerant compressors 12 or 13 is lowered, resulting in oil depletion. There is no failure.
[0035]
BEST MODE FOR CARRYING OUT THE INVENTION6.
  FIG. 8 shows an embodiment of the present invention.6Shows a case where two refrigerant compressors with different capacities are mounted in parallel.
  In the figure, the embodiment of the invention6Is an embodiment of the invention5As compared with the above, the above-described three-way valve 44 is used instead of the electromagnetic valves 41 and 42. The sixth control unit 43 f that controls switching of the flow path of the three-way valve 44 is wired to the three-way valve 44 and the oil level detectors 45 and 46. 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 operated. Is now in circulation. That is, when the first oil level detector 45 is operated, the three-way valve 44 is energized to switch the oil flow path to the first oil return pipe 9 side. 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 the refrigerant compressors 12 and 13 regardless of the turbulence of the oil level in the gas-liquid separator 6. The oil level is not lowered, and there is no problem that causes oil depletion. In addition, when two solenoid valves 41 and 42 are used (the embodiment)5Compared with), the apparatus can be simplified.
[0036]
BEST MODE FOR CARRYING OUT THE INVENTION7.
  FIG. 7 shows an embodiment of the present invention.7Shows a case where two refrigerant compressors with different capacities are mounted in parallel. In the figure, an embodiment of the present invention7Is an embodiment of the invention5Is different from the fifth control unit 43e in that a seventh control unit 43g (in parentheses) having a different function is used. The seventh control unit 43g periodically opens and closes the solenoid valves 41 and 42 so that oil flows into the refrigerant compressors 12 and 13, and the oil level detectors 45 and 46 are operated. Also, the solenoid valves 41 and 42 are opened. That is, the seventh control unit 43g is earlier among the periodic timing when the electromagnetic valves 41 and 42 are opened and the timing when the oil level detectors 45 and 46 related to the electromagnetic valves 41 and 42 are operated. It has the function of opening each solenoid valve 41, 42 according to the time. For example, even before any next solenoid valve 41 or 42 is periodically opened, if any oil level detector 45 or 46 operates, the associated refrigerant compressor 12 or 13 In order to avoid oil depletion, the seventh control unit 43g forcibly opens the corresponding electromagnetic valve 41 or 42. Thereby, the oil can be more reliably returned to the refrigerant compressors 12 and 13 regardless of the turbulence of the oil level in the gas-liquid separator 6, and the oil in either of the refrigerant compressors 1 or 2 can be returned. It is possible to avoid a problem that the surface is lowered and oil is exhausted.
[0037]
In each of the above-described embodiments, an example in which two systems such as a refrigerant compressor, an oil return pipe, and an intake pipe are provided has been described. However, the present invention is not limited to this, and the present invention is also applicable when, for example, three or more systems are provided. Needless to say, you can.
[0038]
【The invention's effect】
  Since the present invention is configured as described above, the following effects can be obtained.
  In a configuration including a plurality of refrigerant compressors having different capacities in parallel, assuming that the seventh control unit periodically opens and closes each solenoid valve, the periodic timing when each solenoid valve is opened and each Since each solenoid valve is opened according to the earlier of the timing when the oil level detector related to the solenoid valve operates, the oil level can be more reliably ensured regardless of the oil level disturbance inside the gas-liquid separator. Can be returned to each refrigerant compressor.
[0039]
  Further, in a configuration including a plurality of refrigerant compressors having different capacities in parallel, the third control unit provides each oil return pipe with an open time corresponding to the capacity ratio of each refrigerant compressor. Since the solenoid valve is opened and closed, the amount of oil corresponding to the compressor capacity ratio can be reliably returned to each refrigerant compressor regardless of the turbulence of the oil level inside the gas-liquid separator.
[0040]
  Further, in a configuration in which a plurality of refrigerant compressors having different capacities are provided in parallel, the oil flow path of the three-way valve is set by the fourth control unit so that the communication time according to the capacity ratio of each refrigerant compressor is obtained. Since switching to the oil return pipe is performed, the amount of oil corresponding to the compressor capacity ratio can be reliably returned to each refrigerant compressor regardless of the turbulence of the oil level inside the gas-liquid separator. The apparatus can be simplified as compared with the case of using a solenoid valve.
[0041]
  In a configuration in which a plurality of refrigerant compressors having different capacities are provided in parallel, the fifth control unit opens an electromagnetic valve related to the refrigerant compressor when the oil level in the refrigerant compressor falls below a predetermined level. Therefore, the oil can be reliably returned to each refrigerant compressor regardless of the turbulence of the oil level inside the gas-liquid separator, and oil depletion can be prevented.
[0042]
  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 by the sixth control unit, the oil return pipe related to the refrigerant compressor is directed to Since the oil flow is switched by switching the oil flow path of the three-way valve, the oil can be reliably returned to each refrigerant compressor regardless of the turbulence of the oil level inside the gas-liquid separator, and oil depletion can be prevented. Can be prevented.
[0043]
  In a configuration in which a plurality of refrigerant compressors having the same capacity are provided in parallel, assuming that the seventh control unit periodically opens and closes each solenoid valve, the periodic timing when each solenoid valve is opened and each Since each solenoid valve is opened according to the earlier of the timing when the oil level detector related to the solenoid valve operates, the oil level can be more reliably ensured regardless of the oil level disturbance inside the gas-liquid separator. Can be returned to each refrigerant compressor.
[0044]
Further, in a configuration in which a plurality of refrigerant compressors having the same capacity are provided in parallel, the first control unit periodically opens the plurality of solenoid valves and sets the opening times of the respective solenoid valves to be the same. Therefore, it is possible to solve the problem that a large amount of oil returns to one refrigerant compressor and oil does not return to another refrigerant compressor, and the oil in the gas-liquid separator is returned to each refrigerant compressor evenly. be able to.
[0045]
  And in the structure equipped with the several refrigerant | coolant compressor with the same capacity | capacitance in parallel, the oil flow path of a three-way valve is periodically switched toward each oil return pipe | tube by the 2nd control part, and to each oil return pipe | tube. The communication time of each is equalized, so that the problem that a lot of oil returns to one refrigerant compressor and the oil does not return to another refrigerant compressor can be solved, and the oil in the gas-liquid separator is removed. In addition to being able to return to the respective refrigerant compressors evenly, the apparatus can be simplified as compared with the case of using a solenoid valve.
[Brief description of the drawings]
FIG. 1 of the present inventionReference exampleIt is a refrigerant | coolant piping system diagram which shows the freezing apparatus concerning 1-3.
FIG. 2 of the present inventionReference example4 is a plan view of an orifice according to FIG.
FIG. 3 of the present inventionReference example4 is a configuration diagram showing a state where an orifice is mounted in the oil return pipe according to FIG.
FIG. 4 of the present inventionReference exampleIt is a refrigerant | coolant piping system diagram which shows the freezing apparatus concerning 5-7.
FIG. 5 shows an embodiment of the present invention.1Or embodiment3It is a refrigerant | coolant piping system diagram which shows the freezing apparatus which concerns on.
FIG. 6 shows an embodiment of the present invention.2Or embodiment4It is a refrigerant | coolant piping system diagram which shows the freezing apparatus which concerns on.
FIG. 7 shows an embodiment of the present invention.5Or embodiment7It is a refrigerant | coolant piping system diagram which shows the freezing apparatus which concerns on.
FIG. 8 is an embodiment of the present invention.6It is a refrigerant | coolant piping system diagram which shows the freezing apparatus which concerns on.
FIG. 9 is a refrigerant piping system diagram showing a conventional refrigeration apparatus.
FIG. 10 is a cross-sectional view showing a gas-liquid separator of a conventional refrigeration apparatus.

Claims (8)

  A plurality of refrigerant compressors, condensers, pressure reducing devices, evaporators, gas-liquid separators, etc., which are provided in parallel with different capacities are sequentially arranged in a circuit, and the upper part of the gas-liquid separator and the plurality of refrigerant compressions are arranged. A plurality of suction pipes connecting the suction side of the compressor in parallel, and a plurality of oil return pipes connecting the lower part of the gas-liquid separator and the suction side of the plurality of refrigerant compressors in parallel, respectively. In the refrigeration apparatus provided, the plurality of solenoid valves provided for each of the plurality of oil return pipes and the plurality of oils respectively provided in the plurality of refrigerant compressors and operating when an oil level in the compressor falls below a predetermined level. The surface detector and each solenoid valve are opened and closed periodically, and according to the earlier timing among the periodic timing when each solenoid valve is opened and the timing when the oil level detector related to each solenoid valve is operated. Seventh control to open each solenoid valve Refrigerating apparatus characterized by comprising comprises a and.   A plurality of solenoid valves provided for each of the plurality of oil return pipes, and a third control unit for opening and closing each solenoid valve so as to have an open time according to the capacity ratio of each refrigerant compressor. The refrigeration apparatus according to claim 1.   A three-way valve provided at a branching position from the lower part of the gas-liquid separator to the plurality of oil return pipes to switch the oil flow path from the gas-liquid separator to be communicable with each oil return pipe; and each refrigerant compressor And a fourth control unit that switches the oil flow path of the three-way valve toward each of the oil return pipes so as to have a communication time corresponding to the capacity ratio. Refrigeration equipment.   A plurality of solenoid valves provided for each of the plurality of oil return pipes, a plurality of oil level detectors each provided in the plurality of refrigerant compressors and operating when the oil level in the compressor falls below a predetermined level; The refrigeration apparatus according to claim 1, further comprising: a fifth control unit that opens a solenoid valve related to the oil level detector when the oil level detector is activated.   A three-way valve provided at a branch position from the lower part of the gas-liquid separator to the plurality of oil return pipes to switch the oil flow path from the gas-liquid separator to each oil return pipe; and the plurality of refrigerants A plurality of oil level detectors that are respectively provided in the compressor and operate when the oil level in the compressor falls below a predetermined level, and toward the oil return pipe related to the oil level detector when the oil level detector operates. The refrigeration apparatus according to claim 1, further comprising a sixth control unit that switches an oil flow path of the three-way valve.   A plurality of refrigerant compressors, condensers, decompressors, evaporators, gas-liquid separators, etc., which are provided in parallel with the same capacity, are sequentially arranged in a circuit, and the upper part of the gas-liquid separator and the plurality of refrigerants A plurality of suction pipes for connecting the suction side of the compressor in parallel with each other; a plurality of oil return pipes for connecting the lower part of the gas-liquid separator and the suction side of the plurality of refrigerant compressors in parallel with each other; A plurality of solenoid valves provided for each of the plurality of oil return pipes, and a plurality of solenoid valves provided in the plurality of refrigerant compressors and operating when an oil level in the compressor falls below a predetermined level. The oil level detector and each solenoid valve are periodically opened and closed, and the earlier timing among the periodic timing at which each solenoid valve is opened and the timing at which the oil level detector associated with each solenoid valve operates. 7th control to open each solenoid valve according to Refrigerating apparatus characterized by comprising comprises a and.   A plurality of solenoid valves provided for each of the plurality of oil return pipes, and a first control unit that periodically opens and closes the solenoid valves so that the open times of the solenoid valves are equal to each other. The refrigeration apparatus according to claim 6.   A three-way valve provided at a branch position from the lower part of the gas-liquid separator to the plurality of oil return pipes to switch the oil flow path from the gas-liquid separator to be communicable with each oil return pipe; 7. A second control unit that periodically switches the oil flow path of the three-way valve toward each of the oil return pipes so that the communication times to the pipes are equal to each other. The refrigeration apparatus described.

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