JP2001349625A - Air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air conditioner capable of assuring a paper amount of fluid required for each of plural compressors when the plural compressors are operated concurrently or when they are individually operated. SOLUTION: There is provided an air conditioner in which plural compressors connected side by side, a four-way valve 2, an outdoor heat exchanger 3, an expansion valve 4, plural indoor heat exchangers 5a, 5b and an accumulator 7 are connected to each other to form a refrigerant circuit. The compressors are constituted by a first compressor 1a, a second compressor 1b and a third compressor 1c. An oil separator is constituted by a first oil separator 8a, a second oil separator 8b and a third oil separator 8c. An opening or closing valve is constituted by a first, a second, a third, a fourth, a fifth and a sixth opening or closing valves 9a, 9b, 9c, and 9f. Each of a uniform oil pipe 1ab and the third compressor 1c is provided with oil level sensors 8a), (b) for use in sensing an oil surface level of each of the compressors so as to control an opening or closing of the third opening or closing valve 9c, the fourth opening or closing valve 9d, the fifth opening or closing valve 9e and the sixth opening or closing valve 9f in response to the oil surface level of each of the compressors detected by the oil level sensors (a), (b).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-type air conditioner having an outdoor unit having a plurality of compressors and a plurality of indoor units, and more particularly, to operating and stopping a plurality of compressors. The present invention relates to an oil leveling system that can make the oil level of each compressor uniform according to the situation.

[0002]

2. Description of the Related Art There is a conventional air conditioner forming a refrigerant circuit, for example, as shown in FIG. In the figure,
21a, 21b, 21c are a plurality of compressors of different capacities connected in parallel, 22 is a four-way valve for switching the flow of refrigerant discharged from the compressors 21a, 21b, 21c in accordance with cooling operation, heating operation, etc., 23 Is an outdoor heat exchanger, 24 is an expansion valve, 25a and 25b are indoor heat exchangers that can be operated simultaneously or arbitrarily, and 26a and 26b
Is an electromagnetic valve, and 27 is an accumulator, which is sequentially connected to form a refrigerant circuit.

A reference numeral 28 communicates a suction pipe 30c upstream of a suction branch portion 29a, 29b to each of the compressors 21a, 21b, 21c with an oil equalizing pipe 31, and reduces the pressure of the oil equalizing pipe 31 to each of the compressors 21a, 21b. , 21c is a communication pipe whose pressure is higher than the pressure inside 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 restrictor at both ends. Here, it is assumed that the compressor 21a has a lower capacity than the compressors 21b and 21c.

In the above configuration, the refrigerant flows in the direction indicated by the solid arrows during the cooling operation, and flows in the direction indicated by the broken arrows during the heating operation. First, during operation of each compressor 21a, 21b, 21c, the communication pipe 28
Therefore, the pressure of the oil equalizing pipe 31 communicating with the suction pipe 30c upstream of the suction branch portions 29a, 29b of the compressors 21a, 21b, 21c is higher than the pressure in the shell of each compressor 21a, 21b, 21c. Become. Therefore, the oil does not move from the low-capacity compressor 21a to the high-capacity compressors 21b and 21c. Also, 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 through the oil equalizing pipe 31. The oil amount of the compressors 21a, 21b, 21c is adjusted so that the oil level is equal.

In the high-capacity compressors 21b and 21c, the returned oil amount is smaller than the discharged oil amount, and the oil amount decreases. In this case, the high-pressure, low-capacity compressor is
The oil moves from the shell 21a to the suction pipe on the high-capacity side where the pressure is low, thereby preventing the amount of oil on the high-capacity side.

However, in the above configuration, the oil equalizing pipe
Although the oil levels of the compressors 21a, 21b, 21c are maintained in equilibrium by the 31, the oil level value varies unless the inner diameter of the oil leveling pipe 31 is considerably large, which is disadvantageous in cost. Further, when compressors having different capacities are used, there is a problem that even if the shells are different in size and the oil level is the same, the required oil amount in each compressor may not be satisfied.

[0007]

SUMMARY OF THE INVENTION In the present invention, in consideration of the above problems, it is necessary to secure an appropriate oil amount required for each compressor when a plurality of compressors are operated simultaneously or individually. It is an object of the present invention to provide an air conditioner that can perform air conditioning.

[0008]

In order to solve the above-mentioned problems, the present invention provides a plurality of compressors, a four-way valve, an outdoor heat exchanger, an expansion valve, and a plurality of indoor heat exchangers connected in parallel. In an air conditioner formed by sequentially connecting a device and an accumulator to form a refrigerant circuit, the plurality of compressors are configured from a first compressor, a second compressor, and a third compressor,
The first oil separator, the first on-off valve and the second oil separator are connected in series between the discharge pipes of the first compressor and the second compressor and the four-way valve, A third oil separator and a second on-off valve are connected in series between a discharge pipe of the third compressor and a connection point between the first on-off valve and the second oil separator, and The first compressor and the second compressor are connected by an oil equalizing pipe, and the oil return pipe of the first oil separator is connected to the first compressor via a third on-off valve and a first throttle. The oil return pipe of the second oil separator is connected in series to a suction pipe, and the first return pipe is branched via a fourth on-off valve and a second throttle and a fifth on-off valve and a third throttle. The oil return pipe of the third oil separator is connected in series to the respective suction pipes of the compressor and the third compressor, and the oil return pipe of the third oil separator is connected through a sixth on-off valve and a fourth throttle. To the suction pipe of the machine An oil level sensor for detecting the oil level of each of the compressors is provided in each of the oil equalizing pipes and the third compressor in a row connection, and the oil level of each of the compressors detected by the respective oil level sensors is provided. Depending on the height,
The third on-off valve, the fourth on-off valve, the fifth on-off valve, and the sixth on-off valve are controlled to open and close.

In addition, an oil level sensor provided in the oil equalizing pipe detects an oil level of the oil level of the first compressor and the second compressor, and an oil level sensor provided in the third compressor. The level sensor detects an upper limit value and a lower limit value of the oil level of the third compressor.

If the oil level detected by the oil level sensor provided in the oil equalizing pipe is equal to or higher than the oil equalizing value, the third on-off valve and the fourth on-off valve are closed, and the oil equalizing value or less is set. In this case, the third on-off valve is repeatedly opened and closed periodically, and at the same time, the fourth on-off valve is controlled to always open.

When the oil level detected by the oil level sensor provided in the third compressor is equal to or higher than the upper limit value, the fifth on-off valve and the sixth on-off valve are closed. In the case, the fifth on-off valve is opened, and when the oil level is between the upper limit value and the lower limit value, the fifth on-off valve is closed, and the sixth on-off valve is repeatedly opened and closed periodically. It is configured to control.

[0012] In addition, each of the on-off valves is configured to use an electromagnetic valve.

[0013] Further, the first and second on-off valves and the second on-off valve are configured using check valves.

Each of the compressors is constituted by a constant speed different capacity compressor.

Further, each of the compressors is constituted by a low-pressure compressor.

The outlet pipe of the accumulator is connected to the suction pipe of each compressor via a distribution pipe.

[0017] Further, a configuration is employed in which a capillary tube is used for the aperture.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be described below in detail based on examples. In FIG. 1, 1
a, 1b, 1c are a plurality of compressors connected in parallel, 2 is a four-way valve for switching the flow of refrigerant discharged from the compressors 1a, 1b, 1c in accordance with cooling operation, heating operation, etc., 3 is 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 solenoid valves, 7 is an accumulator, and these are sequentially connected to form a refrigerant circuit. Has become. In the present embodiment, the plurality of compressors are low-pressure type different capacity compressors for constant speed, a large first compressor 1a and a second compressor 1b, and a small third compressor 1c. It is composed of

A first oil separator 8a and a first opening / closing unit are connected in series between the connection point of the discharge pipes 1a1 and 1b1 of the first compressor 1a and the second compressor 1b and the four-way valve 2. Connect the valve 9a and the second oil separator 8b, and the discharge pipe 1c1 of the third compressor 1b, between the connection point of the first on-off valve 9a and the second oil separator 8b,
A third oil separator 8c and a second on-off valve 9b are connected in series, and the first compressor 1a and the second compressor 1b are connected by an oil equalizing pipe 1ab.

An oil return pipe 8a1 of the first oil separator 8a is connected in series to a suction pipe 1a2 of the first compressor 1a via a third opening / closing valve 9c and a first throttle 10a. Second oil separator 8b
Oil return pipe 8b1 (branch point A) and the fourth on-off valve 9d
And the second throttle 10b and the fifth on-off valve 9e and the third throttle 10
c, connected in series to the respective suction pipes 1a2, 1c2 of the first compressor 1a and the third compressor 1c, and opened and closed the oil return pipe 8c1 of the third oil separator 8c by a sixth opening / closing operation. It is connected in series to a suction pipe 1c2 of the third compressor 1c via a valve 9f and a fourth throttle 10d.

Each of the oil equalizing pipe 1ab and the third compressor 1c is provided with oil level sensors a and b for detecting the oil level of each of the compressors 1a, 1b and 1c. a, b, according to the oil level of each of the compressors 1a, 1b, 1c detected, the third on-off valve 9c, the fourth on-off valve 9d,
The control unit 11 controls the opening and closing of the fifth on-off valve 9e and the sixth on-off valve 9f.
Is controlled by the

The first compressor 1a and the second compressor 1b
When the oil sump returned to the first compressor 1a and the second compressor 1b varies due to the configuration in which the respective oil reservoirs are connected by the oil equalizing pipe 1ab, the equilibrium value is adjusted through the oil equalizing pipe 1ab. Will be kept.

An oil level sensor a provided on the oil equalizing pipe 1ab has one end of a sensor body attached to the oil equalizing pipe 1ab,
The other end is connected to the junction of the suction pipes 1a2, 1b2 of the first compressor 1a and the second compressor 1b via a fifth throttle 10e, and is not affected by a differential pressure. Compressor 1a
And the level of the oil level of the oil level of the second compressor 1b is accurately detected. Further, an oil level sensor b provided in the third compressor 1c detects an upper limit value and a lower limit value of the oil level of the third compressor 1c.

In the above configuration, the refrigerant flows in the direction of the solid line arrow during the cooling operation, and flows in the direction of the broken line 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 and the second compressor 1b is discharged by the first separator 8a to the third separator 8a. 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 by the first separator 8a is an oil return pipe.
8a1 via the third on-off valve 9c and the first throttle 10a, and the suction pipe 1a of the first compressor 1a and the second compressor 1b.
The oil returned to 2,1b2 and separated by the third separator 8c is returned from the oil return pipe 8c1 to the suction pipe 1c2 of the third compressor 1c. The oil separated again by the second separator 8b is returned to the suction pipes 1a2, 1b2, 1c2 of the compressors 1a, 1b, 1c, respectively.

FIG. 2 is a flow chart showing a first control method according to the present embodiment, and shows a control instruction for the oil level sensor a. When the first compressor 1a and the second compressor 1b are started simultaneously or individually, the oil level of the oil equalizing pipe 1ab is detected by the oil level sensor a in step ST1, and the oil level is measured in step ST2. Is determined to be equal to or greater than the oil level. Step ST if oil level
At 4 the third on-off valve 9c and the fourth on-off valve 9d corresponding to the first and second compressors 1a, 1b are closed, and the first and second oil separators 8a and 8b are closed. Oil supply is stopped. If the oil level is equal to or less than the oil level, in step ST3, the third on-off valve 9c is repeatedly opened and closed periodically, and at the same time, the fourth on-off valve 9d is always opened. Oil is supplied so that the oil in the first and second compressors 1a and 1b becomes uniform, and the process returns to step ST1.

FIG. 3 is a flow chart showing a second control method according to the present embodiment, which shows a control instruction for the oil level sensor b. When the operation of the third compressor 1c is started, the oil level sensor b detects the oil level of the third compressor 1c in step ST1, and determines in step ST2 whether the oil level is the upper limit. . If it is equal to or more than the upper limit value, in step ST5, the fifth on-off valve 9e and the sixth on-off valve 9f corresponding to the third compressor 1c are closed, and the second oil separator 8b and the third The supply of oil from the oil separator 8c is stopped. If the oil level is not the upper limit, it is determined in step ST3 whether the oil level is the lower limit. If the oil level is equal to or higher than the lower limit, that is, if the oil level is between the upper limit and the lower limit, the step In ST6, the fifth on-off valve 9e is closed,
At the same time, the sixth on-off valve 9f is periodically opened and closed repeatedly, and the oil amount is kept optimal. If the oil level is below the lower limit,
In step ST4, the fifth on-off valve 9e is opened, and the third compressor
Oil is supplied to 1c, and the process returns to step ST1.

The outlet pipe 7a2 of the accumulator 7
Is distributed to the suction pipes 1a2, 1b2, 1c2 by the distribution pipe 13, and returned to the compressors 1a, 1b, 1c, respectively. In addition, by using a capillary tube for each of the throttles 10a to 10e, the influence of the pressure difference between the compressor and the oil separator is eliminated.

As described above, each of the compressors 1a, 1a
When the b, 1c is operated, the discharged refrigerant containing the oil discharged from each of the compressors 1a, 1b, 1c is separated into oil by the first separator 8a and the third separator 8c. Opening / closing valves 9a and 9b comprising corresponding solenoid valves or check valves are opened, and the refrigerant that has not been separated is completely separated by the second oil separator 8b, and the separated oil is returned to the fourth opening / closing valve. Through the respective suction pipes 1a2, 1b2, 1c2 via the 9d and the fifth on-off valve 9e, the oil is distributed to the compressors 1a, 1b, 1c in accordance with the oil level detected by the oil level sensors a, b and returned. It is. Further, the oil separated in the first separator 8a and the third separator 8c,
According to the oil level detected by the oil level sensors a and b,
In the same manner as described above, the air is distributed to the compressors 1a, 1b, and 1c and returned. As a result, the discharged refrigerant has a good separation efficiency, and each compressor 1
The required oil amount is secured according to the operating conditions of a, 1b, 1c,
An air conditioner that does not cause reliability problems due to lack of oil.

[0029]

As described above, according to the present invention, when each of the compressors is operated, the discharged refrigerant containing the oil discharged from each of the compressors is separated by each of the oil separators, and the corresponding refrigerants are separated. The on-off valve is opened, and the refrigerant that has not been separated is completely separated by the second oil separator, and the separated oil is supplied to the third on-off valve, the fourth on-off valve, the fifth on-off valve and the sixth on-off valve. And then returned through each suction pipe and oil equalizing pipe according to the oil level of each compressor. For this reason, the discharged refrigerant has a good separation efficiency, a necessary amount of oil is secured according to the operation state of each compressor, and the air conditioner does not cause a reliability problem due to a shortage of 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 a first control method of the present invention.

FIG. 3 is a flowchart according to a second control method of the present invention.

FIG. 4 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 7a2 Outlet pipe 8a First oil separator 8b Second oil separator 8c Third oil separator 8a1,8b1,8c1 Oil return pipe 9a First open / close valve 9b Second open / close valve 9c Third open / close valve 9d Fourth on-off valve 9e Fifth on-off valve 9f Sixth on-off valve a, b Oil level sensor 11 Control unit

Claims (10)

[Claims] An air having a refrigerant circuit formed by sequentially connecting a plurality of compressors, a four-way valve, an outdoor heat exchanger, an expansion valve, a plurality of indoor heat exchangers and accumulators connected in parallel. In the harmony machine, the plurality of compressors are configured by a first compressor, a second compressor, and a third compressor, and the discharge pipes of the first compressor and the second compressor, and Between the four-way valve, connect the first oil separator and the first on-off valve and the second oil separator in series, the discharge pipe of the third compressor, the first on-off valve and the second Between the connection point of the two oil separators, a third oil separator and a second on-off valve are connected in series, and the first compressor and the second compressor are connected by an oil equalizing pipe. An oil return pipe of the first oil separator is connected in series to a suction pipe of the first compressor via a third on-off valve and a first throttle,
The oil return pipe of the second oil separator is branched, and the first compressor and the third compressor are passed through a fourth on-off valve and a second throttle and a fifth on-off valve and a third throttle. The oil return pipe of the third oil separator is connected in series to the suction pipe of the third compressor via a sixth on-off valve and a fourth throttle while being connected in series to the respective suction pipes of the compressor. An oil level sensor that detects an oil level of each of the compressors is provided in each of the oil equalizing pipe and the third compressor,
Controlling the opening and closing of the third on-off valve, the fourth on-off valve, the fifth on-off valve and the sixth on-off valve according to the oil level of each compressor detected by the oil level sensor. An air conditioner characterized by comprising: 2. An oil level sensor provided in the oil equalizing pipe detects an oil level of oil levels of the first compressor and the second compressor, and an oil level sensor provided in the third compressor. The air conditioner according to claim 1, wherein a level sensor detects an upper limit value and a lower limit value of an oil level of the third compressor. 3. When the oil level detected by an oil level sensor provided in the oil equalizing pipe is equal to or higher than the oil equalizing value, the third opening / closing valve and the fourth opening / closing valve are closed, and the oil equalizing value or less is set. The air conditioner according to claim 1, wherein, in the case of (1), the third on-off valve is periodically opened and closed, and the fourth on-off valve is always opened. 4. When the oil level detected by an oil level sensor provided in the third compressor is equal to or higher than an upper limit value, the fifth open / close valve and the sixth open / close valve are closed, and the lower limit value is equal to or lower than the lower limit value. In the case, the fifth on-off valve is opened, and when the oil level is between the upper limit value and the lower limit value, the fifth on-off valve is closed, and the sixth on-off valve is repeatedly opened and closed periodically. The air conditioner according to claim 1, wherein the air conditioner is controlled. 5. The air conditioner according to claim 1, wherein an electromagnetic valve is used for each of said on-off valves. 6. The air conditioner according to claim 1, wherein a check valve is used for the first on-off valve and the second on-off valve. 7. The air conditioner according to claim 1, wherein each of the compressors is constituted by a constant speed different capacity compressor. 8. The air conditioner according to claim 1, wherein each of the compressors is constituted by a low-pressure compressor. 9. The air conditioner according to claim 1, wherein an outlet pipe of the accumulator is connected to a suction pipe of each of the compressors via a distribution pipe. 10. The air conditioner according to claim 1, wherein a capillary tube is used for the throttle.