JP4333044B2 - Air conditioner - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a multi-type air conditioner provided with a plurality of compressors in an outdoor unit and provided with a plurality of indoor units, and more specifically, according to the operation and stop status of the plurality of compressors. The present invention relates to an oil leveling system that can make the oil level uniform.
[0002]
[Prior art]
An example of an air conditioner that forms a conventional refrigerant circuit is shown in FIG. In the figure, 21a, 21b, and 21c are a plurality of compressors connected in parallel and having different capacities, and 22 is a four-way switch that switches the refrigerant flow discharged from the compressors 21a, 21b, and 21c according to the cooling operation, heating operation, etc. Valves, 23 are outdoor heat exchangers, 24 are expansion valves, 25a and 25b are indoor heat exchangers that can be operated simultaneously or arbitrarily, and 26a and 26b are electromagnetic valves, which are sequentially connected to form a refrigerant circuit It has a configuration.
[0003]
28 communicates the suction pipes 30c upstream of the suction branch portions 29a, 29b to the compressors 21a, 21b, 21c and the oil leveling pipe 31, and the pressure of the oil leveling pipes 31 is controlled by the compressors 21a, 21b, 21c. It is a communication pipe made higher than the pressure in the shell. Reference numeral 32 denotes a bypass having one end communicating with the shells of the compressors 21b and 21c, the other end communicating with the suction pipe 30a of the compressor 21a, and a throttle in the middle of both ends.
Here, it is assumed that the compressor 21a has a lower capacity than the compressors 21b and 21c.
[0004]
In the above configuration, the refrigerant flows in the direction of the solid arrow during the cooling operation, and flows in the direction of the broken arrow during the heating operation. First, during operation of each compressor 21a, 21b, 21c, the oil equalizing pipe 31 connected to the suction pipe 30c upstream from the suction branching portions 29a, 29b of each compressor 21a, 21b, 21c by the communication pipe 28. The pressure is higher than the pressure in the shell of each compressor 21a, 21b, 21c. Therefore, the oil does not move from the low capacity compressor 21a to the high capacity compressors 21b and 21c. Further, when all the compressors 21a, 21b, 21c are stopped, the pressure in the cycle is equalized, and the oil can be moved between the compressors 21a, 21b, 21c via the oil equalizing pipe 31. The amount of oil in the compressors 21a, 21b, 21c is adjusted so that the oil level is equal.
[0005]
Further, in the high capacity compressors 21b and 21c, the oil return amount is small with respect to the discharge oil amount, and the oil amount decreases. In this case, since the oil moves from the shell of the compressor 21a on the low-capacity side with high pressure to the suction pipe on the high-capacity side with low pressure, the bypass 32 prevents the amount of oil on the high-capacity side.
[0006]
However, in the above configuration, the oil level of the compressors 21a, 21b, and 21c is maintained in equilibrium by the oil leveling pipe 31, but the oil level value varies as long as the inner diameter of the oil leveling pipe 31 is not significantly thick. Disadvantageous.
Further, when compressors with different capacities are used, there is a problem that even if the shells are different in size and the oil level is the same, there is a risk that the required amount of oil in each compressor may not be satisfied.
[0007]
[Problems to be solved by the invention]
In the present invention, in view of the above-described problems, an air conditioner that can secure an appropriate amount of oil necessary for each compressor when a plurality of compressors are operated simultaneously or individually is provided. With the goal.
[0008]
[Means for Solving the Problems]
In order to solve the above problems, the present invention sequentially connects a plurality of compressors connected in parallel, a four-way valve, an outdoor heat exchanger, an expansion valve, a plurality of indoor heat exchangers, and an accumulator. In the air conditioner formed by
The plurality of compressors includes a first compressor, a second compressor, and a third compressor, and the first compressor is connected in series between a discharge pipe of the first compressor and the four-way valve. An on-off valve, a first oil separator, a seventh on-off valve and a second oil separator, a discharge pipe of the second compressor and the third compressor, and the second oil A third oil separator and an eighth on-off valve are connected in series between the first compressor and the second on-off valve via a second on-off valve and a third on-off valve, respectively. The compressor and the third compressor are connected by an oil equalizing pipe and a pressure equalizing pipe,
The oil return pipe of the first oil separator is connected in series to the suction pipe of the first compressor via a fourth on-off valve, and the oil return pipe of the second oil separator is connected to a sixth The oil return pipe of the third oil separator is connected to the fifth oil separator while being connected in series to the junction of the suction pipes of the first compressor, the second compressor, and the third compressor via an on-off valve. An oil level sensor and a throttle are connected in series between the oil equalizing pipe and the pressure equalizing pipe in series with the junction of the suction pipes of the second compressor and the third compressor via an on-off valve. The opening / closing of the sixth on-off valve is controlled according to the oil level detected by the sensor.
[0009]
Further, the oil level sensor is configured to detect an upper limit value and a lower limit value of the oil level of each compressor.
[0010]
When the oil level detected by the oil level sensor exceeds the upper limit, the sixth on-off valve is closed, and when the oil level is between the upper limit and the lower limit, The six on-off valves are periodically opened and closed, and when the oil level is lower than the lower limit value or lower limit value, the sixth on-off valve is controlled to open.
[0011]
In addition, the fourth on-off valve and the fifth on-off valve are periodically controlled to open and close according to the operation time of each compressor.
[0012]
In addition, an electromagnetic valve is used for each on-off valve.
[0013]
The first on-off valve, the second on-off valve, the third on-off valve, the seventh on-off valve, and the eighth on-off valve are configured to use check valves.
[0014]
Moreover, each said compressor was comprised with the different capability compressor for constant speeds.
[0015]
Moreover, each said compressor was comprised with the low pressure type compressor.
[0016]
Further, the oil equalizing pipe is connected on the low pressure side of each compressor.
[0017]
Further, the outlet pipe of the accumulator is connected to the suction pipe of each compressor via a distribution pipe.
[0018]
In addition, a capillary tube is used for the diaphragm.
[0019]
In addition, a plurality of holes are provided in the outlet pipe of the accumulator.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail based on examples.
In FIG. 1, 1a, 1b, 1c are a plurality of compressors connected in parallel, 2 is a four-way valve that switches the flow of refrigerant discharged from each compressor 1a, 1b, 1c according to the cooling operation, heating operation, etc. 3 is an outdoor heat exchanger, 4 is an expansion valve, 5a and 5b are indoor heat exchangers that can be operated simultaneously or arbitrarily, 6a and 6b are electromagnetic valves, and 7 is an accumulator, which are connected in sequence to form a refrigerant circuit It is the structure which formed.
In this embodiment, the plurality of compressors are low-pressure different capacity compressors for constant speed, a large first compressor 1a, a medium second compressor 1b, and a small third compression. And machine 1c.
[0021]
Between the discharge pipe 1a1 of the first compressor 1a and the four-way valve 2, a first on-off valve 9a, a first oil separator 8a, a seventh on-off valve 9g and a second oil separation are connected in series. 8b, and the discharge pipe 1b1 of the second compressor 1b and the discharge pipe 1c1 of the third compressor 1b are connected in parallel via the second on-off valve 9b and the third on-off valve 9c, respectively. The third oil separator 8c and the eighth on-off valve 9h are connected in series between the connection point and the second oil separator 8b, and the first compressor 1a and the second oil separator 8b are connected in series. The compressor 1b and the third compressor 1c are connected by oil equalizing pipes 12a and 12b and pressure equalizing pipes 13a and 13b.
[0022]
The oil return pipe 8a1 of the first oil separator 8a is connected in series to the suction pipe 1a2 of the first compressor 1a via a fourth on-off valve 9d, and the oil of the third oil separator 8c is connected. The return pipe 8c1 is connected in series to the junction 1bc of the suction pipe 1b2 of the second compressor 1b and the suction pipe 1c2 of the third compressor 1c via the fifth on-off valve 9e, and the second oil The oil return pipe 8b1 of the separator 8b is connected in series via a sixth on-off valve 9f to the junction 1abc of the suction pipes 1a2, 1b2, 1c2 of the compressors 1a, 1b, 1c.
[0023]
Between the oil equalizing pipe 12a and the pressure equalizing pipe 13a, an oil level sensor 11 for detecting the oil level of the compressors 1a, 1b, 1c and a throttle 11a are connected in series, and the oil level sensor 11 detects the oil level sensor 11. The controller 11 controls the opening and closing of the fourth on-off valve 9d, the fifth on-off valve 9e, and the sixth on-off valve 9f in accordance with the oil level height of the compressors 1a, 1b, 1c. It has become.
If there is a variation in the amount of oil in each of the compressors 1a, 1b, 1c, the equilibrium value is maintained through the oil equalizing pipes 12a, 12b. If there is a pressure variation, the equilibrium value is maintained through the pressure equalizing pipes 13a, 13b. Be drunk.
[0024]
The oil level sensor 11 has one end of a sensor body attached to the oil equalizing pipe 12a and the other end connected to the pressure equalizing pipe 13a via a throttle 11a, and without being affected by the differential pressure, the compressors 1a, The upper limit value and lower limit value of the oil level of 1b and 1c are accurately detected.
[0025]
In the above configuration, the refrigerant flows in the direction of the solid arrow during the cooling operation, and flows in the direction of the broken arrow during the heating operation. When each of the compressors 1a, 1b, 1c is operated, the discharged refrigerant containing the oil discharged from the first compressor 1a is the first separator 8a, and the second compressor 1b and the third compressor 1a. The refrigerant discharged from the compressor 1c is separated by the third separator 8c, and the refrigerant that has not been separated is separated again by the second separator 8b.
The oil separated in the first separator 8a is returned to the suction pipe 1a2 of the first compressor 1a from the oil return pipe 8a1 via the fourth on-off valve 9d, and the third separator The oil separated in 8c is returned from the oil return pipe 8c1 to the suction pipe 1b2 of the second compressor 1b and the suction pipe 1c2 of the third compressor 1c via the fifth on-off valve 9e.
[0026]
The oil re-separated by the second separator 8b is returned to the suction pipes 1a2, 1b2, and 1c2 from the merging pipe 1abc of the suction pipes of the compressors 1a, 1b, and 1c.
In addition, when the compressors 1a, 1b, and 1c are individually operated, the second separator 8b has a second separator 8b in order to prevent the refrigerant from flowing back to the second separator 8b and the third separator 8c. Seven on-off valves 9g are provided in the third separator 8c, and an eighth on-off valve 9h is provided.
[0027]
When the oil level detected by the oil level sensor 11 exceeds the upper limit, the sixth on-off valve 9f is closed, and when the oil level is between the upper limit and the lower limit, The six on-off valves 9f are repeatedly opened and closed periodically, and when the oil level is lower than the lower limit value or lower limit value, the sixth on-off valve 9f is controlled to always open, and the compressors 1a, 1b , 1c according to the operation time, the fourth on-off valve 9d and the fifth on-off valve 9e are regularly controlled to open and close, so that the oil return amount of each compressor 1a, 1b, 1c is uniform. And an air conditioner that does not cause reliability problems due to lack of oil.
[0028]
FIG. 2 is a flowchart showing the control method of this embodiment. When the first compressor 1a, the second compressor 1b and the third compressor 1c are started simultaneously or individually, the oil level sensor 11 detects the height of the oil leveling pipe 12a in step ST1. In step ST2, it is determined whether the oil level is equal to or higher than the upper limit value. If it is equal to or greater than the upper limit value, the sixth on-off valve 9f is closed in step ST3, and the supply of oil from the second oil separator 8b to the compressors 1a, 1b, 1c is stopped. If the oil level is not greater than or equal to the upper limit, it is determined in step ST4 whether the oil level is between the upper limit and the lower limit. If it is between the upper limit and the lower limit, in step ST5, the sixth on-off valve 9f periodically repeats opening and closing. If the oil level is not between the upper limit value and the lower limit value, it is determined in step ST6 whether the oil level height is the lower limit value or less. If it is the lower limit value or less, the sixth on-off valve 9f is always opened in step ST7, and oil is supplied so that the oil in the compressors 1a, 1b, 1c is uniform. If it is not the lower limit value or less, the process returns to step ST1 and the operation is repeated.
[0029]
The refrigerant in the outlet pipe 7a of the accumulator 7 is distributed to the suction pipes 1a2, 1b2, 1c2 by the distribution pipe 14, and returned to the compressors 1a, 1b, 1c, respectively.
Further, by using a capillary tube for the throttle 11a, the influence of the differential pressure between the compressor and the oil separator is eliminated.
In addition, a plurality of holes 7b are provided at equal intervals in the outlet pipe 7a of the accumulator 7, so that oil does not accumulate inside the accumulator 7.
[0030]
As described above, when the compressors 1a, 1b, 1c are operated, the discharged refrigerant containing the oil discharged from the compressors 1a, 1b, 1c is the first separator 8a and the second separator 8a. Oil is separated by the third separator 8c, and the oil separated by the first separator 8a is sucked into the first compressor 1a from the oil return pipe 8a1 via the fourth on-off valve 9d. The oil returned to the pipe 1a2 and separated by the third separator 8c passes through the fifth on-off valve 9e from the oil return pipe 8c1 and the suction pipe 1b2 and the third compressor of the second compressor 1b. It is returned to the suction pipe 1c2 of 1c.
The refrigerant that has not been separated and separated is completely separated by the second oil separator 8b, and the separated oil passes through the fourth on-off valve 9d and the fifth on-off valve 9e to each of the suction pipes 1a2, 1b2. , 1c2 and distributed back to the compressors 1a, 1b, 1c according to the oil level detected by the oil level sensors a, b.
As a result, the discharged refrigerant has a high separation efficiency, and the required amount of oil is ensured according to the operating conditions of the compressors 1a, 1b, 1c, and the air conditioner does not cause a problem of reliability due to lack of oil.
[0031]
【The invention's effect】
As described above, according to the present invention, when each compressor is operated, the discharged refrigerant containing the oil discharged from each compressor is separated by each oil separator, and the corresponding on-off valve is opened. The refrigerant that has not been separated and separated is completely separated by the second oil separator, and the separated oil is returned to the compressor according to the oil level of each compressor through each intake pipe via the sixth on-off valve. It is. For this reason, the discharged refrigerant has a high separation efficiency, and a required amount of oil is ensured according to the operation status of each compressor, so that the air conditioner does not cause a problem of reliability due to insufficient oil in each compressor.
[Brief description of the drawings]
FIG. 1 is a refrigerant circuit diagram of an air conditioner according to the present invention.
FIG. 2 is a flowchart according to the control method of the present invention.
FIG. 3 is a refrigerant circuit diagram of an air conditioner according to a conventional example.
[Explanation of symbols]
1a First compressor
1b Second compressor
1c Third compressor
1a1,1b1,1c1 Discharge pipe
1a2,1b2,1c2 Suction pipe 2 Four-way valve 3 Outdoor heat exchanger 4 Expansion valve
5a, 5b Indoor heat exchanger 7 Accumulator
7a outlet pipe
8a 1st oil separator
8b Second oil separator
8c Third oil separator
8a1,8b1,8c1 Oil return pipe
9a First on-off valve
9b Second on-off valve
9c Third on-off valve
9d 4th on-off valve
9e Fifth open / close valve
9f Sixth on-off valve
9g 7th open / close valve
9h Eighth on-off valve
10 Control unit
11 Oil level sensor
11a Aperture
12a, 12b Oil leveling pipe
13a, 13b Pressure equalizing pipe
14 minutes piping

Claims (12)

In an air conditioner in which a plurality of compressors connected in parallel, a four-way valve, an outdoor heat exchanger, an expansion valve, a plurality of indoor heat exchangers and an accumulator are sequentially connected to form a refrigerant circuit.
The plurality of compressors includes a first compressor, a second compressor, and a third compressor, and the first compressor is connected in series between a discharge pipe of the first compressor and the four-way valve. An on-off valve, a first oil separator, a seventh on-off valve and a second oil separator, a discharge pipe of the second compressor and the third compressor, and the second oil A third oil separator and an eighth on-off valve are connected in series between the first compressor and the second on-off valve via a second on-off valve and a third on-off valve, respectively. The compressor and the third compressor are connected by an oil equalizing pipe and a pressure equalizing pipe,
The oil return pipe of the first oil separator is connected in series to the suction pipe of the first compressor via a fourth on-off valve, and the oil return pipe of the second oil separator is connected to a sixth The oil return pipe of the third oil separator is connected to the fifth oil separator while being connected in series to the junction of the suction pipes of the first compressor, the second compressor, and the third compressor via an on-off valve. An oil level sensor and a throttle are connected in series between the oil equalizing pipe and the pressure equalizing pipe in series with the junction of the suction pipes of the second compressor and the third compressor via an on-off valve. An air conditioner characterized by controlling the opening and closing of the sixth on-off valve in accordance with the oil level detected by the sensor. The air conditioner according to claim 1, wherein the oil level sensor detects an upper limit value and a lower limit value of an oil level of each compressor. When the oil level detected by the oil level sensor exceeds the upper limit, the sixth on-off valve is closed, and when the oil level is between the upper limit and the lower limit, the sixth 2. The air conditioner according to claim 1, wherein the on-off valve is periodically opened and closed, and the sixth on-off valve is controlled to open when the oil level is lower than the lower limit or lower limit. Machine. 2. The air conditioner according to claim 1, wherein the fourth on-off valve and the fifth on-off valve are periodically controlled to open / close in accordance with an operation time of each compressor. The air conditioner according to claim 1, 3 or 4, wherein an electromagnetic valve is used for each on-off valve. The air according to claim 1, wherein a check valve is used for the first on-off valve, the second on-off valve, the third on-off valve, the seventh on-off valve, and the eighth on-off valve. Harmony machine. The air conditioner according to claim 1, wherein each of the compressors is constituted by a constant speed different capacity compressor. The air conditioner according to claim 1, wherein each of the compressors is constituted by a low-pressure compressor. The air conditioner according to claim 1, wherein the oil equalizing pipe is connected to a low pressure side of each compressor. The air conditioner according to claim 1, wherein an outlet pipe of the accumulator is connected to a suction pipe of each compressor via a distribution pipe. The air conditioner according to claim 1, wherein a capillary tube is used for the restriction. The air conditioner according to claim 1, wherein a plurality of holes are provided in an outlet pipe of the accumulator.

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