JPH10220883A - Outdoor unit for air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an outdoor unit for an air conditioner, which realizes the equalizing of oil levels in a plurality of compressors. SOLUTION: First to third communicating tubes 101-103 are provided with a plurality (2-3) of curved units near the connecting site to respective compressors 3-5 and are formed so as to retain horizontal or descending condition from the connecting sites of respective compressors 3-5 to a joining unit or a T-joint (not shown in a diagram). When oil levels OL1-OL3 have become uneven in respective compressors 3-5, refrigerating machine oil is moved through a level equilibrium tube during stopping of the air conditioner whereby the unevenness is eliminated gradually. On the other hand, an outdoor side ECU drives the first - third compressors 3 sequentially for a short period of time at every given times to contrive the equilibrium of the oil levels OL1-OL3 forcibly.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an outdoor unit of an air conditioner having a plurality of low-pressure vessel compressors, and more particularly, to a technique for leveling an oil level among the low-pressure vessel compressors.

[0002]

2. Description of the Related Art In recent years, as an air conditioner used for cooling and heating of a large store or a gymnasium, a large-capacity outdoor unit has been used in order to simplify the device configuration and temperature / humidity control and to reduce manufacturing costs. A large space type in which a large number of indoor units are connected to each other is often used. In this type of air conditioner, one outdoor unit incorporates a plurality of relatively large low-pressure vessel compressors (such as scroll compressors and reciprocating compressors), and the number of operating compressors and electric fans A suitable amount of liquid refrigerant or gas refrigerant is supplied to each indoor unit by controlling the amount of air blown or the like.

In general, in an air conditioner, refrigerating machine oil is stored in a lower portion of a compressor casing, and a mixed fluid of the refrigerating machine oil and the refrigerant circulates in a refrigerant circuit, so that the refrigerant in the compressor, the expansion valve, and the like is generated. The rotating part and the sliding part are lubricated. The mixed fluid is pressure-fed from the outdoor unit to the indoor unit by the discharge force of the compressor, and is returned to the outdoor unit after being subjected to heat exchange in the indoor heat exchanger. At this time, part of the refrigerating machine oil is separated from the mixed fluid by an oil separator or the like provided downstream of the compressor and returned to the casing of the compressor.

[0004]

In the large space type air conditioner described above, for example, when one of a plurality of compressors is driven for a long time, the oil level of the compressor excessively increases (casing). The amount of refrigerating machine oil inside may be excessive). Then, in the compressor where the oil level has risen excessively,
In addition to an increase in energy loss due to an increase in stirring resistance, there have been problems such as insulation breakdown of windings of the electric motor caused by immersion in refrigeration oil. Also, in this case, the oil level of other compressors tends to fall below the allowable limit, so that the lubrication of the compression mechanism and the drive shaft bearings cannot be smoothly performed at the time of restart, and damage or seizure of these members. Was sometimes brought.

Therefore, conventionally, attempts have been made to level the oil level by connecting the casings of the compressors with oil equalizing pipes made of copper pipes or the like. However, as is well known, the compressor vibrates constantly during operation, and when the air conditioner is operated for a long period of time, cracks occur in the oil equalizing pipe and the refrigerating machine oil and the refrigerant leak. There was a fear. In addition, when a portion of the oil equalizing pipe that protrudes upward is present, gas refrigerant accumulates in the portion, and the circulation of the refrigerating machine oil is obstructed, so that the function as the oil equalizing pipe may not be performed. Furthermore, during the operation of the air conditioner, there is a problem that the oil level is hardly leveled by the oil equalizing pipe because the internal pressure of the casing of the driven compressor decreases.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an outdoor unit of an air conditioner in which an oil level is leveled among a plurality of compressors.

[0007]

Therefore, according to the present invention, there is provided an outdoor unit of an air conditioner having a plurality of low-pressure container compressors, wherein the casings of the low-pressure container compressors communicate with each other. In addition, the present invention proposes an outdoor unit for an air conditioner, comprising: an oil equalizing pipe having a plurality of bent portions formed near a connection portion with each of the low-pressure container compressors.

According to the present invention, even if a large relative movement occurs in the compressor due to vibration during operation, the relative movement is absorbed in each bent portion, and cracks are less likely to occur in the oil equalizing pipe.

According to a second aspect of the present invention, there is provided an outdoor unit of an air conditioner having three or more low-pressure container compressors, wherein the casings of the low-pressure container compressors communicate with each other, and An outdoor unit for an air conditioner, comprising: an oil equalizing pipe formed so as to maintain a horizontal or lowered state from a connection part with a container compressor to a pipe junction part.

According to the present invention, there is no portion in which the gas refrigerant accumulates in the pipeline of the oil equalizing pipe, and the circulation of the refrigerating machine oil is not hindered.

According to a third aspect of the present invention, in the outdoor unit of the air conditioner according to the first or second aspect, during operation of the air conditioner, each of the low-pressure container compressors is specified one by one at a predetermined timing. A compressor having a compressor drive control unit that is driven over time is proposed.

According to the present invention, the refrigerating machine oil in the low-pressure container compressor whose oil level has risen excessively rises due to the successive decrease in the internal pressure of the casing of each low-pressure container compressor, and is sent to another low-pressure container compressor via the oil equalizing pipe. It flows in and the oil level is leveled in a very short time.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic configuration diagram of an air conditioner including one outdoor unit 1 and a number of indoor units 2, in which a solid line indicates a refrigerant circuit, and a dashed line indicates an electric circuit. is there.

On the side of the outdoor unit 1, there are first to third outdoor heat exchangers provided with first to third compressors 3 to 5, an electromagnetic four-way valve 6, a flow regulator 7 and a liquid line valve 8. Devices 9 to 11, first to third electric fans 12 to 14, an accumulator 15, and the like. On the indoor unit 2 side, an electric expansion valve 31, an indoor heat exchanger 32, an electric fan 33 and the like are installed. And the equipment which comprises an outdoor unit and an indoor unit is connected by the refrigerant | coolant piping 41-65 used for distribution of a gas refrigerant or a liquid refrigerant. In the figure, reference numeral 66 denotes an oil equalizing pipe for mutually communicating the casings of the first to third compressors 3 to 5, and 67 and 68 denote the outdoor unit 1
This is a service valve provided for connection between the refrigerant pipes 53 and 58 on the side and the refrigerant pipes 54 and 57 on the indoor unit 2 side.

In the case of this embodiment, the first to third compressors 3 to 3
Numeral 5 is a scroll type constant speed compressor having a capacity of 10 hp, and each has an oil separator 21 attached thereto. Also, among the first to third electric fans 12 to 14, the first and third electric fans 12, 14 are of a constant speed type having a three-phase motor, while the second electric fan is provided with a single-phase motor. Variable speed type. In FIG. 1, reference numeral 22 denotes a manual refrigerant shut-off valve interposed between the four-way valve 6 and the outdoor heat exchangers 7 to 9, and reference numeral 23 denotes a backflow of liquid refrigerant to each of the compressors 3 to 5. Check valve. Reference numerals 24 and 25 are first and second liquid valves for cooling the compressor. Reference numeral 26 denotes a low-voltage switch disposed downstream of the accumulator 15;
Is a high-pressure switch disposed downstream of each of the compressors 3-5.

In the outdoor unit 1, an outdoor control unit (hereinafter, referred to as an outdoor ECU) 71 including a CPU, an input / output interface, a ROM, a RAM, and the like is provided. The outdoor ECU 71 is configured to control the compressors 3 to 5, the four-way valve 9, and the electric fans 12 to 1 based on a built-in control program and input information from various sensors including the low pressure switch 26 and the high pressure switch 27.
4 and so on.

On the other hand, the indoor unit 2 includes an indoor control unit (hereinafter referred to as an indoor EC) comprising a CPU, an input / output interface, a ROM, a RAM, and the like.
U) 72 are provided. Indoor ECU 72
Is based on input signals from a built-in control program and a remote controller (not shown) and various sensors.
The drive control of the electric expansion valve 31 and the electric fan 33 is performed, and signals are exchanged with the outdoor ECU 71.

Next, the flow of the refrigerant during the cooling operation will be described.

From the accumulator 15 to the refrigerant pipes 60 to 6
The gas refrigerant sucked into the first to third compressors 3 to 5 via the compressor 3 is adiabatically compressed and discharged as a high-temperature high-pressure gas refrigerant. The route of the discharged high-pressure gas refrigerant is controlled by the four-way valve 9 via the refrigerant pipes 41 to 44, and then the first to third outdoor heat exchangers 9 to 11 are transmitted via the refrigerant pipes 46 to 49. Flows into. The high-temperature and high-pressure gas refrigerant is cooled by the outside air while passing through these outdoor heat exchangers 9 to 11 and condensed to become a liquid refrigerant. Flows into the electric expansion valve 31.

At this time, the outdoor ECU 71 appropriately controls the driving of the first to third compressors 3 to 5 and the first to third electric fans 12 to 14 according to the required horsepower and the like. Also, the first to first
When any one of the third compressors 3 to 5 is overheated, the first and second liquid valves 24 and 25 are appropriately opened, and the first to third compressors 3 to 5 are connected via the refrigerant pipes 64 and 65. To supply cooling liquid refrigerant. If air-conditioning operation is not performed,
The outdoor ECU 71 closes the liquid line valve 8 to prevent refrigerant stagnation (condensation) in each of the compressors 3 to 5 and each of the outdoor heat exchangers 9 to 11.

After the flow rate of the liquid refrigerant is controlled by the electric expansion valve 31, the liquid refrigerant flows into the indoor heat exchanger 32,
While passing through the inside, it is vaporized and becomes a gas refrigerant, and the indoor air blown by the electric fan 33 is cooled by the vaporized latent heat. At this time, the indoor ECU 72 controls the number of revolutions of the electric fan 33 based on the deviation between the set temperature and the room temperature, and sets the deviation between the inlet-side refrigerant temperature and the outlet-side refrigerant temperature of the indoor heat exchanger 23 to a predetermined value ( For example, the valve opening amount of the electric expansion valve 31 (the number of steps of the stepping motor for driving the valve body) is controlled so as to be 0 to 1 ° C.).

The gas refrigerant vaporized in the indoor heat exchanger 32 is
The refrigerant flows into the accumulator 15 via the refrigerant pipes 56 to 58, the four-way valve 6, and the refrigerant pipe 59, and is sucked again from the refrigerant pipes 60 to 63 into the first to third compressors 3 to 5.

On the other hand, during the heating operation, the four-way valve 6 is switched as indicated by a broken line, and the flow of the refrigerant is also opposite to that during the cooling operation, as indicated by the broken arrow. That is, first to first
The high-temperature high-pressure gas refrigerant discharged from the third compressors 3 to 5 is introduced into the indoor heat exchanger 32,
While passing through the inside 2, the refrigerant condenses into a liquid refrigerant, and the indoor air blown by the electric fan 33 is heated by the condensation latent heat. Next, the liquid refrigerant flows into the first to third outdoor heat exchangers 9 to 11, is heated by the outside air while passing through the inside thereof, and is vaporized to become a gas refrigerant. It is sucked into the first to third compressors 3 to 5 again.

Hereinafter, the structure of the outdoor unit 1 will be described.

FIG. 2 is a plan view of the outdoor unit 1, and FIG. 3 is a front view of the same. As shown in these drawings, the outdoor unit 1 has a horizontally long rectangular parallelepiped appearance, and an outdoor heat exchanger 9-1 is provided between the substrate 81 and the top plate 82.
1 (only the first and second outdoor heat exchangers 9 and 11 are shown in FIG. 3) and a detachable decorative panel (outer plate) 83 are provided. In the figure, reference numeral 84 denotes a suction grille for protecting the heat exchangers 9 to 11. Further, the top plate 81 is formed with three circular outlets 85 at equal intervals, and the outlets 85 are provided with concentric outlet grills 86. Then, as shown in FIG. 2, the outside air flows into the outdoor unit 1 from the entire outer periphery except for the decorative panel 83, and then is discharged from each outlet 85 as shown in FIG. In the figure, 87
Are end support pillars arranged at four corners of the outdoor unit 1.

FIG. 4 is a plan view of the outdoor unit 1 with the top plate 82 removed, and FIG. 5 shows a state in which the decorative panel 83 is removed and front portions of the first and second outdoor heat exchangers 9 and 11 are cut away. FIG. 3 is a front view of the outdoor unit 1 in a state in which the outdoor unit 1 is in a retracted state. As shown in these figures, the first to third compressors 3 to 5 are mounted on the central portion of the substrate 81, and the first to third electric fans 12 to 14
Are disposed below each outlet 85. The outdoor unit 1 is provided with an electrical box 91 containing an outdoor ECU 71 and the like in the center of the front surface thereof. By removing the decorative panel 83, various switches and the like can be accessed. In the figure, reference numerals 92 and 93 denote a pair of left and right front support pillars (outer plates) provided for supporting the decorative panel 83 and the electrical box 91, and are joined to the substrate 81 and the top plate 82.

FIG. 6 shows the first to third compressors 3 on the substrate 81.
FIG. 7 is a plan view showing a layout of the oil equalizing pipe 66, and FIG. 7 is a front view of the same. As shown in these drawings, the first to third compressors 3 to 5 each have a connection pipe 100 projecting from a lower portion thereof, and a casing inside via a lubrication pipe 66 connected to the connection pipe 100. Are communicated with each other. In addition, when the same amount of refrigerating machine oil is stored in each of the compressors 3 to 5, the connection pipe 100 is connected to each of the compressors 3 to 5.
The oil levels OL1 to OL3 (shown by a two-dot chain line) are set to be substantially the same position.

The oil equalizing pipe 66 is made of a first pipe made of copper pipe.
To the third communication pipes 101 to 103 and a T-shaped joint 105 made of a copper alloy, which are integrated by brazing. Further, in the case of the present embodiment, the T-shaped joint 105 has a predetermined amount (for example, 2 mm) with respect to a connection portion between the first to third communication pipes 101 to 103 and the compressors 3 to 5.
0-30 mm) below.

Each of the first to third communication pipes 101 to 103 has a plurality of (2 to 3) bent portions in the vicinity of a connection portion with each of the compressors 3 to 5, and is connected to each of the compressors 3 to 5. It is formed so as to maintain a horizontal or lowered state from the connection portion to the T-shaped joint 105 serving as a junction. Accordingly, in the present embodiment, the first to third communication pipes 1 are provided together with the first to third compressors 3 to 5.
Even when 01 to 103 vibrate, the vibration is effectively absorbed in the bent portion, and cracks and the like are less likely to occur on the pipe walls of the communication pipes 101 to 103. Moreover, since there is no upwardly protruding portion in the communication pipes 101 to 103 between the connection portion with each of the compressors 3 to 5 and the T-shaped joint 105 where air and gas refrigerant are stored, the refrigerant oil is The movement between the compressors 3 to 5 is performed smoothly.

In this embodiment, when the oil levels OL1 to OL3 among the compressors 3 to 5 become non-uniform,
When the refrigerating machine oil moves through the oil equalizing pipe while the air conditioner is stopped, the unevenness is gradually eliminated. However, during the operation of the air conditioner, as described above, the internal pressure of the operating compressor decreases, so that the oil levels
The non-uniformity of L3 is hardly eliminated. So, outdoor EC
At the same time as the operation of the air conditioner is started, U71 executes the oil balance control subroutine shown in the flowchart of FIG. 8 at a predetermined control interval in order to forcibly level the oil levels OL1 to OL3.

When this subroutine is started, the outdoor E
First, in step S1, the CU 71 determines whether or not the standby flag Fwait having the initial value of 0 is 1; if this determination is No,
In step S3, the wait flag Fwait is set to 1 and the timer T is started at the same time. Then, the outdoor ECU 71
Determines in step S5 whether or not the value of the timer T having the initial value 0 has exceeded a predetermined standby time Ta (for example, 60 minutes), and returns to the start and repeats the determination while this determination is No. .

If 60 minutes have elapsed since the start of the timer T and the determination in step S5 is Yes, the outdoor ECU 71
Is the first to perform oil balance control in step S7.
To sequentially drive the third to third compressors 3 to 5. That is, regardless of the required horsepower at the present time, the outdoor ECU 71 operates the first to third compressors 3 for a first predetermined time (30 seconds in this embodiment), as shown in the time chart of FIG. Are sequentially driven, and when the drive is switched, a second predetermined time (in the present embodiment,
3 seconds) Pause.

FIGS. 10 to 12 show, for example, the oil level OL of the first compressor 3 during the oil balance control.
1, the oil level OL of the second and third compressors 4, 5
2, the movement of the refrigerating machine oil when OL3 is low is schematically shown.

First, when only the first compressor 3 is driven,
The internal pressure of the first compressor 3 decreases with respect to the second and third compressors 4 and 5. However, since the oil levels OL2 and OL3 of the second and third compressors 4 and 5 are lower than the position of the connection pipe 100 as shown in FIG. Does not move to the first compressor 3 via the oil equalizing pipe 66.

Next, when only the second compressor 4 is driven,
The internal pressure of the second compressor 4 decreases with respect to the first and third compressors 3 and 5. At this time, as shown in FIG. 11, since the oil level OL1 of the first compressor 3 is higher than the position of the connection pipe 100, the refrigerating machine oil in the first compressor 3 passes through the second oil equalization pipe 66 to the second oil level. Move to compressor 4.

Next, when only the third compressor 5 is driven,
The internal pressure of the third compressor 5 decreases with respect to the first and second compressors 3 and 4. In this case, as shown in FIG.
Since the oil levels OL1, OL2 of the second compressors 3, 4 are higher than the position of the connection pipe 100, the first and second compressors 3, 4
The refrigerating machine oil inside moves to the third compressor 5 via the oil equalizing pipe 66.

As described above, when the outdoor ECU 71 sequentially drives the first to third compressors 3 to 5, the oil equalizing pipe 66 is controlled.
The refrigerating machine oil is appropriately moved via the above, and the oil levels OL1 to OL3 of the compressors 3 to 5 are leveled. Outdoor ECU
When the oil balance control is completed in step S7, the standby flag Fwait is reset to 0 in step S9, and the process returns to the start.
The driving of the third compressors 3 to 5 is controlled. The oil balance control subroutine is executed every time the value of the timer T exceeds the predetermined standby time Ta, so that the oil level of the specific compressor does not excessively increase or decrease to below the allowable limit, and the above-described various operations are performed. The defect is eliminated.

The description of the specific embodiment has been completed.
Embodiments of the present invention are not limited to this. For example,
In the above embodiment, the present invention is applied to an outdoor unit having three compressors, but may be applied to an outdoor unit having two or four or more compressors. Also,
In addition to the specific shape of the oil equalizing pipe, the standby time during the oil balance control, the driving time of the compressor, and the like, the refrigerant circuit and the electric circuit of the air conditioner can be appropriately changed without departing from the spirit of the present invention. It is.

[0039]

As described above, according to the present invention,
In an outdoor unit of an air conditioner having a plurality of low-pressure container compressors, a plurality of bent portions are formed in the vicinity of a connection portion with each compressor, or a horizontal or descending state is maintained from a connection portion to a pipe junction. Since the compressors are communicated by the formed oil equalizing pipes, cracks do not occur in the oil equalizing pipes, and the flow of refrigerating machine oil between the compressors is not hindered.

In the air conditioner, when each compressor is driven one by one at a predetermined timing for a predetermined time during operation of the air conditioner, the refrigerating machine oil in the compressor in which the oil level has risen excessively is equalized. The oil flows into another compressor through the oil pipe, and the oil level is leveled in a very short time.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an air conditioner according to the present invention.

FIG. 2 is a plan view showing an embodiment of an outdoor unit.

FIG. 3 is a front view showing an embodiment of the outdoor unit.

FIG. 4 is a plan view of the outdoor unit with a top plate 82 removed.

FIG. 5 is a front view of the outdoor unit with a decorative panel removed.

FIG. 6 is a plan view showing a layout of a compressor and an oil equalizing pipe.

FIG. 7 is a front view showing a layout of a compressor and an oil equalizing pipe.

FIG. 8 is a flowchart showing a procedure of an oil balance control subroutine.

FIG. 9 is a time chart showing a driving state of a compressor under oil balance control.

FIG. 10 is an explanatory diagram showing movement of refrigeration oil.

FIG. 11 is an explanatory diagram showing movement of refrigeration oil.

FIG. 12 is an explanatory diagram showing movement of refrigeration oil.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Outdoor unit 3-5 1st-3rd compressor 66 Oil equalizing pipe 71 Outdoor ECU 100 Connection pipe 101-103 1st-3rd communication pipe 105 T-type joint

Claims (3)

[Claims] 1. An outdoor unit of an air conditioner having a plurality of low-pressure container compressors, wherein the casings of the low-pressure container compressors communicate with each other and near a connection portion with each of the low-pressure container compressors. An outdoor unit for an air conditioner, comprising: an oil equalizing pipe formed with a plurality of bent portions. 2. An outdoor unit of an air conditioner having three or more low-pressure container compressors, wherein a casing of each of the low-pressure container compressors communicates with each other, and a connection portion with each of the low-pressure container compressors. An outdoor unit for an air conditioner, comprising: an oil equalizing pipe formed so as to maintain a horizontal or downward state from a pipe to a pipe junction. 3. The compressor according to claim 1, further comprising compressor drive control means for driving each of said low-pressure container compressors one by one at a predetermined timing for a predetermined time during operation of the air conditioner. Or the outdoor unit of the air conditioner of 2.