JP5329078B2 - Oil leveling system for high pressure shell compressor used in air conditioner - Google Patents

Description

  The present invention relates to an oil leveling system for an air conditioner in which a plurality of high-pressure shell compressors are arranged in parallel.

  Conventionally, in an air conditioner in which a high-pressure shell type variable speed compressor and a constant speed compressor are arranged in parallel, an oil leveling system for balancing oil between the compressors is provided as a discharge pipe on the high pressure side of the compressor. And what was provided between the suction pipes which are the low voltage | pressure side is known (patent document 1).

  For example, as shown in FIG. 1, for example, as shown in FIG. 1, oil discharge bypass B6 connecting oil leveling ports B11, B21 provided near the standard oil level height of each compressor B1, B2 and the discharge pipe B8. And an oil equalizing circuit B5 for connecting the suction pipe B7 to the downstream side of the connection point of the oil discharge bypass B6 in the discharge pipe B8.

  The oil leveling circuit B5 is provided with an electromagnetic valve B51 and a pressure reducing part B52.

  The discharge pipe B8 is provided with a check valve B3 downstream of the connection point of the oil equalization circuit B5 and upstream of the junction of the discharge pipe.

  When both the compressors B1 and B2 are operating during the cooling and heating operation, both the solenoid valves B51 are closed, and surplus oil of the compressors B1 and B2 is discharged from the oil discharge bypass B6 to the discharge pipe B8. And is distributed to the compressors B1 and B2, whereby oil equalization is performed between the compressors B1 and B2.

  Further, when the constant speed compressor B2 is stopped during the air conditioning operation, the surplus oil is discharged to the suction pipe B7 by opening the solenoid valve B51 of the corresponding oil equalizing circuit B5, and the surplus oil Is distributed to the variable speed compressor B1 in operation, the effective oil amount can be increased.

  Further, since a check valve B3 is provided between the junctions of the compressors B1 and B2 and the discharge pipe B8, the refrigerant can be prevented from entering the stationary constant speed compressor B2 and liquid refrigerant can be prevented from staying. be able to.

Further, when only the variable speed compressor B1 is operated and the small capacity operation is performed, the electromagnetic valve B51 of the corresponding oil leveling circuit B5 is closed, and there is no high / low pressure bypass by the oil leveling pipe. In addition, since there is no refrigerant that continues to circulate only between the oil leveling pipe and the variable speed compressor B1, it is possible to prevent the cooling and heating efficiency from being reduced during small capacity operation.
Japanese Patent No. 3848098

  However, when the oil equalization ports B11 and B21 and the discharge pipe B8 are connected by the oil discharge bypass B6 as described above, the oil forming that the refrigerant dissolved in the oil boils when the variable speed compressor B1 is started. When this occurs, a large amount of oil flows into the indoor unit (not shown) through the oil discharge bypass B6 and the discharge pipe B8.

  Even if the solenoid valve B51 is opened, as shown by the arrow in FIG. 2, most of the oil flows toward the discharge pipe B8 having a larger pipe diameter than the oil equalizing circuit B5. Therefore, it cannot be fundamentally solved that a large amount of oil flows out to the indoor unit side.

  This phenomenon can be explained from the equation (1) of the refrigerant flow rate flowing through the straight pipe.

Q = πd ⁴ Δp / 128 μL (1)

  here,

  Q: Refrigerant flow rate d: Pipe inner diameter Δp: Pressure loss μ: Refrigerant viscosity L: Pipe length

  It is.

(1) the refrigerant flow rate through the straight pipe as shown in equation proportional to the pipe inside diameter d ^4, usually the inner diameter of the oil equalizing circuit B5 is a 1 / 2-1 / 3 with respect to the inner diameter of the discharge pipe B8 From the design, it can be seen that the flow rate of refrigerant flowing through the oil equalization circuit B5 is 1/16 to 1/81 of the flow rate of refrigerant flowing through the discharge pipe B8.

  Since the oil is distributed in proportion to the refrigerant flow rate, when oil forming occurs, only 1/16 to 1/81 of the amount of oil flowing out to the discharge pipe B8 is passed through the oil equalization circuit B5 to the suction pipe. Without returning to B7, the remainder flows into the indoor unit, causing a problem that the oil in the compressors B1 and B2 is insufficient for a long time.

  Furthermore, since the oil equalization circuit B5 is provided for each of the compressors B1 and B2, the number of parts increases, which hinders cost reduction.

  In view of the above problems, the present invention can maintain the oil level of each compressor properly in a short time even if oil forming occurs at the start of the compressor while taking advantage of the characteristics of the existing oil leveling system. An object of the present invention is to provide an air conditioner capable of reducing the cost.

  That is, the air conditioner according to the present invention derives refrigerant from a plurality of high-pressure shell compressors including a variable speed compressor and a constant speed compressor via a discharge pipe, and supplies the refrigerant to the compressor via a suction pipe. In the air conditioner configured to introduce a gas bypass, the discharge pipe and the suction pipe are connected via an electromagnetic valve, and a gas bypass for adjusting high and low pressures having an inner diameter smaller than that of the discharge pipe, and the variable speed compressor An oil discharge bypass connecting the variable speed compressor oil leveling port provided near the standard oil level height and the solenoid valve upstream side of the gas bypass, and provided near the standard oil level height of the constant speed compressor And an oil equalization bypass connecting the suction pipe with the constant-speed compressor.

  Here, the “high pressure shell compressor” refers to a compressor in which the pressure in the hermetic container of the compressor is substantially equal to the discharge pressure.

  If this is the case, even if a large amount of oil flows out of the variable speed compressor due to oil forming during start-up, if the gas bypass is opened by a solenoid valve, most of the oil that has flowed out of the gas bypass It can be returned to the compressor via the suction pipe, and the amount of oil flowing out to the discharge pipe having a large pipe diameter can be reduced as compared with the conventional case. As a result, since the amount of oil flowing out to the indoor unit side can be reduced, the oil level of the compressor can be kept appropriate in a short time.

  Also, when the variable speed compressor and constant speed compressor are both operating during normal air conditioning operation, excess oil from the variable speed compressor is discharged from the oil discharge bypass to the discharge pipe via the gas bypass. While being discharged and distributed to each compressor via the indoor unit, surplus oil of the constant speed compressor is discharged from the oil equalization bypass to the suction pipe and distributed to each compressor. The oil leveling in between can be suitably performed.

  In addition, when the constant speed compressor is stopped during normal air-conditioning operation, operation is performed after excess oil from the constant speed compressor is discharged from the oil equalization bypass to the intake pipe in the same manner as during operation. Since the oil is distributed to the compressor, the effective oil amount can be increased.

  In addition, during small capacity operation where only the variable speed compressor is operated, the gas bypass is closed by a solenoid valve, so that the refrigerant discharged from the variable speed compressor passes through the gas bypass to the variable speed compressor. Since the return can be hindered, it is possible to prevent a decrease in the cooling / heating efficiency during the small capacity operation.

  While oil forming is taking place, a large amount of oil does not flow out to the indoor unit side, and after oil forming is completed, the normal air-conditioning operation is shifted to improve the operating efficiency. It is preferable to further include an electromagnetic valve control means that is opened for a predetermined time from the start of the machine and then closed.

  Since the variable speed compressor is always operated during cooling and heating, liquid refrigerant is hardly stored. Therefore, in order to prevent refrigerant from entering the compressor that is stopped during cooling and heating from the discharge pipe side and to prevent liquid refrigerant from staying, it is necessary to provide a check valve only on the discharge pipe on the constant speed compressor side. desirable. Moreover, if it does in this way, cost reduction can be aimed at compared with what provided the check valve in both.

  During small-capacity operation, the constant speed compressor stops and the compressor's sealed container becomes equal to the suction pressure by shutting off the high-pressure circuit with the check valve and communicating with the low-pressure circuit with the oil equalization bypass. Part of the refrigerant does not circulate due to the oil bypass, and the cooling / heating efficiency does not decrease. Therefore, it is preferable that the oil equalization bypass is configured to connect the constant speed compressor oil equalization port and the suction pipe directly without going through the on-off valve. As a result, the cost can be reduced by omitting the on-off valve. it can.

  The air conditioner according to the present invention configured as described above can maintain the oil level of each compressor appropriately in a short time even if oil forming occurs at the time of starting the compressor, and can reduce the cost. It is. Furthermore, when a plurality of compressors are operating during the cooling / heating operation, it is possible to perform oil leveling between the compressors, and even if the constant speed compressor is stopped during the cooling / heating operation, excess oil is discharged. In addition, the liquid refrigerant does not stay in the stopped compressor, and there is also a feature of the existing air conditioner that the cooling / heating efficiency does not decrease even during the small capacity operation.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  As shown in FIG. 3, the outdoor unit A of the air conditioner 100 according to the present embodiment includes a variable speed compressor 1 and a constant speed compressor 2 that are arranged in parallel, a four-way valve A1 that switches between cooling and heating, and outside air. A heat exchanger A3 that performs heat exchange of the refrigerant, a variable valve A4 that adjusts the state of the refrigerant flowing into the indoor unit, and an accumulator A2 that separates the liquid component of the refrigerant and sends only the gas component to the compressor. Each component is connected by piping.

  The piping around the variable speed compressor 1 and the constant speed compressor 2 will be described in detail.

  Each of the variable speed compressor 1 and the constant speed compressor 2 is connected to a discharge pipe 8 for discharging the refrigerant and a suction pipe 7 for sucking the refrigerant. A gas bypass 4 for adjusting high and low pressure is provided between the pipe 7. Furthermore, the variable speed compressor oil leveling port 11 provided in the vicinity of the standard oil level height of the variable speed compressor 1 and the gas bypass 4 as pipes for leveling the oil between the compressors 1 and 2. And an oil discharge bypass 6 for connecting the suction pipe 7 and the constant speed compressor oil leveling port 21 provided at the standard oil level height of the constant speed compressor 2. ing.

  Each part will be described.

  The variable speed compressor 1 compresses and discharges the sucked refrigerant, and can change the discharge amount by an external signal. In the present embodiment, the variable speed compressor is configured to always operate during the air conditioning operation.

  The constant speed compressor 2 compresses the sucked refrigerant and discharges it with a constant pressure. In the present embodiment, it is configured to stop at the time of small capacity operation.

  The discharge pipe 8 extends from the variable speed compressor 1 and the constant speed compressor 2 and joins the four-way valve A1 after joining. A check valve 3 is provided between the junction 81 in the discharge pipe 8 and the constant speed compressor 2 so that the refrigerant does not flow back from the discharge pipe 8 to the constant speed compressor 2.

  The suction pipe 7 extends from the accumulator A2, branches in the middle, and is connected to the variable speed compressor 1 and the constant speed compressor 2, respectively.

  The gas bypass 4 is provided with the electromagnetic valve 41 and a gas bypass decompression unit 42. This gas bypass 4 connects between the junction point 11 of the discharge pipe 8 and the four-way valve A1 to between the accumulator A2 of the suction pipe 7 and the branch point 71. The gas bypass decompression section 42 The inner diameter of the portion excluding is set to 1/2 to 1/3 with respect to the discharge pipe 8. The reason why the pipe diameter of the gas bypass 4 is made thinner than the discharge pipe 8 is to prevent a large amount of refrigerant that does not contribute to cooling and heating from flowing and to prevent COP from decreasing. Further, the high and low pressures are adjusted using the gas bypass 4 during a small capacity operation in which a suction pressure drop during cooling or a discharge pressure rise during heating is likely to occur, and a normal operation with a large load of refrigerant circulation This is also because there is no need to bypass a large amount of refrigerant because it is less than sometimes.

  The electromagnetic valve 4 can be remotely controlled to open and close by receiving an open / close signal, and the open / close signal is output from the electromagnetic valve control means 9. The electromagnetic valve control means 9 is constituted by, for example, a dedicated electric circuit or a computer.

  The gas bypass pressure-reducing unit 42 serves as a resistance to the flow of the refrigerant, and the gas bypass pressure-reducing unit 42 can perform, for example, high-low pressure adjustment during small capacity operation. The flow path resistance of the gas bypass decompression unit 42 is originally to reduce the refrigerant passing through the gas bypass in order to adjust the high and low pressures by reducing the inner diameter dimension, etc., and adjust the high and low pressures during small capacity operation. Therefore, in this embodiment, the flow path resistance is set to be small so that oil discharged from the variable speed compressor at the time of startup can be discharged. However, if this is done, more refrigerant than necessary will flow from the discharge pipe 8 to the suction pipe 7, and the efficiency will be significantly reduced during high-low pressure adjustment during small capacity operation. The time is set to be shorter than when the gas bypass pressure reducing unit 42 is set to the original flow path resistance value.

  The oil discharge bypass 6 connects the variable speed compressor oil equalizing port 11 and the upstream side of the solenoid valve 41 of the gas bypass, and has the same pipe diameter as that of the portion of the gas bypass 4 excluding the gas bypass decompression section 42. It has a diameter.

  One end of the oil equalization bypass 5 is connected to the constant speed compressor oil equalization port 21, and variable oil compression is performed on excess oil stored above the constant speed compressor oil equalization port 21. It is configured to discharge to the suction pipe 7 on the machine 1 side. The flow rate capacity of the oil equalization bypass 5 is set on the condition that the oil amount of the constant speed compressor 2 increases, such as when the variable speed compressor 1 is operating at a large capacity. A valve or the like is not provided in the middle of the oil equalization bypass 5, and only the oil equalization bypass pressure reducing unit 51 for reducing the pressure of the refrigerant flowing from the constant speed compressor 2 is provided.

  Next, operation | movement of the air conditioning apparatus 100 at the time of a compressor starting is demonstrated with the behavior of oil using FIG.

  When the compressor is activated, only the variable speed compressor 1 operates, and the electromagnetic valve 41 is opened by the electromagnetic valve control means 9. When the variable speed compressor 1 is started, particularly when the outside air temperature is low, oil forming occurs and a large amount of oil flows out of the variable speed compressor 1. This large amount of oil flows into the gas bypass 4 through the oil discharge bypass 6.

  At this time, since the discharge pipe 8 has a higher pressure than the suction pipe 7, a part of the oil flowing into the gas bypass 4 flows to the suction pipe 7, and a large amount of oil is compressed as compared with the conventional piping method. Returned to the machine.

  When it is time to stop a large amount of oil from flowing out of the variable speed compressor 1 due to oil forming, the solenoid valve 41 is closed and the operation is switched to the normal air conditioning operation.

  The time during which a large amount of oil does not flow out by this oil forming is experimentally determined in advance and stored in the electromagnetic valve control means 9. For example, install a sight glass that can monitor the oil behavior in the compressor shell or discharge pipe, start the compressor that has been left at low temperature for a long time, until oil forming and a large amount of oil flow finish It is sufficient to measure the time.

  The operation of the air conditioner 100 during the air conditioning operation and the oil behavior will be described.

  During the cooling / heating operation, the solenoid valve 41 of the gas bypass 4 is closed, so that excess oil of the variable speed compressor 1 is discharged to the discharge pipe 8 and is compressed through an indoor unit (not shown). It is distributed to machines 1 and 2.

  Excess oil of the constant speed compressor 2 is discharged from the oil equalization bypass 5 to the suction pipe 7 and distributed to the compressors 1 and 2 when the constant speed compressor 2 is operating.

  When the constant speed compressor 2 is not in operation, excess oil is discharged from the oil equalization bypass 5 to the suction pipe 7 in the same manner as when the constant speed compressor 2 is in operation. Distributed.

  In the small capacity operation, the heating set temperature is higher than the standard use condition, the pressure on the discharge pipe 8 side is higher than the specified value, or the cooling set temperature is lower than the standard use condition. When the pressure in the suction pipe 7 is lower than a specified value, the electromagnetic valve 41 is opened for a certain period of time in order to adjust the pressure between the discharge pipe 8 and the suction pipe 7.

  As described above, according to the air conditioner 100 according to the present embodiment, the oil discharge bypass 6 is not connected to the discharge pipe 8, but the high-low pressure adjustment gas bypass 4 having an inner diameter smaller than that of the discharge pipe 6. Even if a large amount of oil flows out of the variable speed compressor 1 due to the occurrence of oil forming at the time of start-up, the solenoid valve 41 is opened and a part of the amount of oil that has flowed out is passed through the gas bypass 4. It can return to the suction pipe 7 side via, and can return to each compressor 1,2. As a result, the amount of oil flowing out to the indoor unit can be significantly reduced, so that the oil level of the compressor can be kept appropriate in a short time.

  Furthermore, in order to return the oil that has flowed out when oil forming occurs to the suction pipe 7, the existing gas bypass 4 provided for high and low pressure adjustment between the discharge pipe 8 and the suction pipe 7 is used. Therefore, there is no need to newly provide piping for oil equalization, and a new cost increase is not caused.

  The solenoid valve control means 9 is configured to open the solenoid valve 41 when the variable speed compressor 1 is started, and close the solenoid valve 41 when a large amount of oil does not flow out due to oil forming. It is possible to improve the operation efficiency by switching to the normal air conditioning operation after the oil forming is completed while preventing the oil from flowing out to the indoor unit (not shown).

  When both the variable compressor 1 and the constant speed compressor 2 are operating during normal air conditioning operation, surplus oil in the variable speed compressor 1 passes from the oil discharge bypass 6 via the gas bypass 4, The oil is discharged to the discharge pipe 8 and distributed to the compressors 1 and 2 via an indoor unit (not shown). Excess oil of the constant speed compressor 2 is discharged from the oil equalization bypass 5 to the suction pipe 7 and compressed. Since the oil is distributed to the machines 1 and 2, the oil leveling between the compressors 1 and 2 can be performed.

  When the constant speed compressor 2 is not in operation during the cooling / heating operation, surplus oil in the constant speed compressor 2 is discharged from the oil equalization bypass 5 to the suction pipe 7, and the variable speed compressor 1 in operation is operating. Therefore, the effective oil amount can be increased.

  In the variable speed compressor 1 that operates during the small capacity operation, the solenoid valve 41 is closed under standard use conditions, so that the refrigerant does not return to the compressors 1 and 2 via the gas bypass 4. Therefore, since there is no refrigerant that circulates only between the gas bypass 4 and the variable speed compressor 1, it is possible to prevent the cooling and heating efficiency from being reduced during the small capacity operation.

  Since the check valve 3 is installed in the discharge pipe 8 of the constant speed compressor 2, even when the constant speed compressor 2 is stopped during the cooling and heating operation, the constant speed compressor is discharged from the discharge pipe 8 on the high pressure side. It is possible to prevent liquid refrigerant from staying in the compressor without entering the interior of the compressor.

  The variable speed compressor 1 is always operated during cooling and heating, and liquid refrigerant is unlikely to enter the variable speed compressor 1 from the discharge pipe 8. Therefore, a check valve is provided on the discharge pipe 8 on the variable speed compressor 1 side. Not provided. That is, since the check valve 3 is provided only in the discharge pipe 8 on the constant speed compressor 2 side, it is a component compared to an air conditioner in which check valves are provided in both the variable speed compressor and the constant speed compressor. The score can be reduced.

  Since the constant speed compressor 2 is stopped during the small capacity operation, even if the constant speed compressor 2 is provided with the oil equalization bypass 5 for bypassing high and low pressure, the air conditioning efficiency is not lowered at all. No open / close valve is provided in 5. That is, since the constant speed compressor oil equalizing port 2 and the suction pipe 7 are connected without using the on-off valve, the number of parts can be further reduced and the cost can be reduced.

  The present invention is not limited to the illustrated examples and embodiments, and various modifications can be made without departing from the spirit of the invention.

  For example, even if the solenoid valve 41 is always opened, it is possible to prevent oil from flowing out to the indoor unit due to oil forming at the time of startup.

  The discharge pipe 8 on the variable speed compressor 1 side may also be provided with the check valve 3. If it is such, for example, when the air conditioner 100 is stopped, the refrigerant flows backward from the discharge pipe 8 to the variable speed compressor 1, and the refrigerant is stored in the variable speed compressor 1. Can be prevented.

  If the oil equalization bypass 5 is provided with an opening / closing valve, when there is no need to equalize oil during operation of the constant speed compressor 2, the oil equalization bypass 5 and the constant speed are closed by closing the opening / closing valve. The refrigerant circulating between the compressor 2 can be eliminated, and the efficiency of air conditioning can be increased.

The schematic diagram of the conventional air conditioning apparatus. The schematic diagram of the oil behavior at the time of starting of the conventional air conditioning apparatus. The schematic diagram of the air conditioning apparatus which concerns on one Embodiment of this invention. The schematic diagram of the oil behavior at the time of starting of the air conditioning apparatus which concerns on one Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Air conditioning apparatus 1 ... Variable speed compressor 11 ... Variable speed compressor oil equalizing port 2 ... Constant speed compressor 22 ... Constant speed compressor oil equalizing port 3 ... Reverse Stop valve 4 ... Gas bypass 41 ... Solenoid valve 5 ... Oil equalization bypass 6 ... Oil discharge bypass 7 ... Suction pipe 8 ... Discharge pipe 9 ... Solenoid valve control means

Claims (4)

In an air conditioner configured to derive a refrigerant from a plurality of high-pressure shell compressors including a variable speed compressor and a constant speed compressor via a discharge pipe and introduce the refrigerant to the compressor via a suction pipe ,
Connecting the discharge pipe and the suction pipe via a solenoid valve, a gas bypass for high and low pressure adjustment having a smaller inner diameter than the discharge pipe;
An oil discharge bypass for connecting a variable speed compressor oil leveling port provided near the standard oil level height of the variable speed compressor and the solenoid valve upstream side of the gas bypass;
A constant speed compressor oil leveling port provided near the standard oil level height of the constant speed compressor, and an oil leveling bypass connecting the suction pipe ,
With the solenoid valve closed, excess oil of the variable speed compressor is distributed from the variable speed oil distribution port to each compressor via the oil discharge bypass, gas bypass, discharge pipe, and indoor unit in this order. It is comprised so that it may be performed . The air conditioning apparatus characterized by the above-mentioned .   The air conditioning apparatus according to claim 1, further comprising electromagnetic valve control means for opening the electromagnetic valve for a predetermined time from the start of the variable speed compressor.   The air conditioner according to claim 1 or 2, wherein a check valve is provided only in the discharge pipe on the constant speed compressor side. The air conditioner according to claim 1, 2 or 3, wherein the oil equalization bypass directly connects the constant speed compressor oil equalization port and the suction pipe without an on-off valve.