JP2001182983A - Air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air conditioner in which the r.p.m. or the pressure of an outdoor unit under operation can be balanced. SOLUTION: The air conditioner comprises a plurality of outdoor units 1 coupled in parallel through inter-unit piping extended from load machines 3a, 3b. The air conditioner further comprises means for controlling the number of operating outdoor units 1 depending on the air conditioning load, and means for operating the ratio of the rated r.p.m. of each outdoor unit 1 operating under control of operating number to the actual r.p.m., comparing the highest ratio with the lowest ratio and arranging the ratio of respective outdoor units when the difference between the highest ratio and the lowest ratio exceeds a predetermined value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner having a plurality of outdoor units, and to an operation control of each outdoor unit.

[0002]

2. Description of the Related Art In general, there is known an air conditioner in which a plurality of outdoor units are connected in parallel to interunit piping extending from a load unit. In this type, the air conditioning load is estimated from the temperature difference between the set temperature in the indoor unit (load unit) and the temperature of the air actually sucked in or the temperature difference between the set temperature and the air actually blown out. A centralized control device is provided for calculating the air conditioning load to be borne by each of the outdoor units. This centralized control device constantly monitors the air conditioning load and shares the air conditioning load with each outdoor unit so that the rotational speed of the compressor of each outdoor unit and the refrigerant pressure are constant.

[0003]

However, in the conventional configuration, the centralized control device only instructs each outdoor unit on the air-conditioning load to be shared, and controls the rotational speed of the compressor and the refrigerant pressure of each outdoor unit. Rather than controlling directly, each outdoor unit independently controls the number of revolutions of the compressor and the refrigerant pressure according to the shared air conditioning load.

[0004] For this reason, for example, depending on the installation location of each outdoor unit, if the operating environment is different due to a difference in the outside air temperature due to the quality of the sun or a difference in the air permeability due to a variation in the ventilation due to the poor ventilation. A difference in the number of rotations of the compressor and a difference in refrigerant pressure are generated between the outdoor units with respect to the air conditioning load. As a result, there is a problem that refrigerant is likely to accumulate in the outdoor unit having a low rotation speed or a low pressure and the operation of the apparatus becomes unstable.

It is an object of the present invention to provide an air conditioner capable of solving the above-mentioned problems of the prior art and maintaining the balance of the number of revolutions or pressure of the outdoor unit during operation.

[0006]

According to the first aspect of the present invention,
In an air conditioner in which a plurality of outdoor units are connected in parallel to piping between units extending from a load unit, means for controlling the number of the outdoor units to be operated according to the air conditioning load, Calculate the ratio of the actual rotation speed to the rated rotation speed of the unit, compare the maximum ratio and the minimum ratio of this ratio, and when the deviation between the maximum ratio and the minimum ratio exceeds the specified value, Means for making the ratio uniform.

According to the first aspect of the present invention, the number of operating units is controlled, and the ratio of the actual rotational speed to the rated rotational speed of the outdoor unit being operated is calculated. In comparison, when the deviation between the highest ratio and the lowest ratio exceeds a specified value, a means for equalizing the ratio of each outdoor unit is provided, so that each outdoor unit is a numerical value necessary to calculate this ratio. The actual rotation speeds are aligned. By making the actual rotational speeds uniform, the pressures of the refrigerant flowing into and out of the unit-to-unit piping from each outdoor unit are made uniform, the operation balance is maintained, and the refrigerant can be prevented from accumulating in a specific outdoor unit.

According to a second aspect of the present invention, there is provided an air conditioner in which a plurality of outdoor units are connected in parallel to an inter-unit pipe extending from a load unit, a means for controlling the number of the outdoor units to be operated according to an air conditioning load. The refrigerant pressure of each outdoor unit that is controlled and operated is measured, and the maximum pressure and the minimum pressure among the refrigerant pressures are compared, and when the deviation between the maximum pressure and the minimum pressure exceeds a specified value, Means for equalizing the pressure of each outdoor unit.

According to the second aspect of the present invention, the number of operating units is controlled, the refrigerant pressure of the outdoor unit being operated is measured, and the maximum pressure and the minimum pressure of the refrigerant pressure are compared to determine the maximum pressure and the maximum pressure. When the deviation from the minimum pressure exceeds a specified value, a means for equalizing the pressure of each outdoor unit is provided, so that the pressure of the refrigerant flowing into and out of the unit-to-unit piping from each outdoor unit is equalized, and the balance of operation is improved. Thus, the refrigerant can be prevented from accumulating in the specific outdoor unit.

A third aspect of the present invention is characterized in that, in the second aspect of the invention, the refrigerant pressure on the low pressure side is measured in the heating operation mode.

According to a fourth aspect of the present invention, in the second aspect of the present invention, the refrigerant pressure on the high pressure side is measured in the cooling operation mode.

According to the third and fourth aspects of the present invention, the refrigerant pressure on the low pressure side is measured during the heating operation. Therefore, a measuring device such as a pressure sensor for measuring the refrigerant pressure is required to perform the refrigerant pressure measurement on the high pressure side during the cooling operation. Will be measured. Therefore, regardless of the heating operation and the cooling operation, the refrigerant pressure can be detected by one measuring device in each outdoor unit, and it is not necessary to provide a plurality of measuring devices, and the cost can be reduced.

According to a fifth aspect of the present invention, there is provided an air conditioner in which a plurality of outdoor units are connected in parallel to an inter-unit pipe extending from a load unit, a means for controlling the number of operating outdoor units in accordance with an air conditioning load. Calculates the ratio of the actual rotation speed to the rated rotation speed of each outdoor unit that is controlled and operated,
The maximum ratio and the minimum ratio of the ratios are compared, and when the deviation between the maximum ratio and the minimum ratio exceeds a specified value, a means for equalizing the ratio of each outdoor unit and the number of the outdoor units are controlled to operate. Measure the refrigerant pressure of each outdoor unit, compare the maximum pressure and the minimum pressure of this refrigerant pressure, when the deviation between the maximum pressure and the minimum pressure exceeds a specified value, align the pressure of each outdoor unit Means.

According to the fifth aspect of the present invention, the number of operating units is controlled, the ratio of the actual rotational speed to the rated rotational speed of the outdoor unit being operated is calculated, and the highest ratio and the lowest ratio of the ratios are calculated. In comparison, when the deviation between the highest ratio and the lowest ratio exceeds a specified value, a means for equalizing the ratio of each outdoor unit is provided, and the refrigerant pressure of the outdoor unit being operated is measured. The maximum pressure and the minimum pressure are compared, and when the deviation between the maximum pressure and the minimum pressure exceeds a specified value, there is provided a means for equalizing the pressure of each outdoor unit. Even when the actual rotation speeds of the outdoor units are the same, for example, even when the actual rotation speeds are the same and the refrigerant pressures are different due to problems such as piping, the means for equalizing the refrigerant pressures allows the units to be connected from each outdoor unit to the unit. Of the refrigerant flowing into and out of the piping Force is justified, the balance of the operation is maintained.

According to a sixth aspect of the present invention, in the first or fifth aspect, the means for equalizing the ratios calculates an individual load factor of each outdoor unit based on the ratio of each outdoor unit. Multiply the rated capacity of the outdoor unit by the individual load factor, calculate the surplus load of the outdoor unit under operation control based on the multiplied value, subtract the surplus load from the rated total capacity of each outdoor unit, The overall load factor of the outdoor unit is obtained, and based on the overall load factor, the target rotational speed of the outdoor unit under operation control is calculated, and the actual rotational speeds of the outdoor unit are aligned to match the target rotational speed. The ratios are made uniform.

According to the present invention, since the actual rotation speed of the compressor of each outdoor unit during operation is made equal to the calculated target rotation speed, the load on each outdoor unit during operation is equalized, and the refrigerant The pressure becomes constant, and the balance of operation in each outdoor unit is maintained.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, 1a and 1b denote outdoor units, and 3a and 3b denote indoor units. The outdoor unit 1a
Accumulator 10a, compressor 11a driven by gas engine, oil separator 12a, four-way valve 13
a, an outdoor heat exchanger 14a, and an outdoor electric expansion valve 15a
It is composed of 17a is the outdoor heat exchanger 14.
The fan of a is shown. The outdoor unit 1b is the same as the outdoor unit 1a, including the following configuration, and a description thereof will be omitted.

The indoor unit 3a includes an indoor heat exchanger 34a.
And an indoor electric expansion valve 35a (hereinafter referred to as “indoor mechanical valve 35”).
a ". ). The indoor unit 3b
Is the same as that of the indoor unit 3a, including the following configuration, and a description thereof will be omitted. From the indoor units 3a and 3b, inter-unit pipes including the gas pipe 5 and the liquid pipe 7 extend, and the outdoor units 1a and 1b are connected in parallel to the inter-unit pipes.

The oil separator 12a includes a compressor 11a
To separate the lubricating oil in the refrigerant discharged from the
The lubricating oil separated here is always returned to the compressor 11a through the oil return pipe 21a and the forced oil return pipe 22a. A capillary tube 24a is always provided in the oil return pipe 21a, and a flow path resistance is applied to oil returned to the compressor 11a by the capillary tube 24a. This constant oil return pipe 21a is connected in the middle of the oil separator 12a, and as long as the oil level of the oil in the oil separator 12a is higher than the position where the oil return pipe 21a is connected, the oil is constantly supplied to the compressor 11a through the constant oil return pipe 21a. It is returned to the suction pipe. On-off valves 23a and 25a are provided in the forced oil return pipe 22a.
The forced oil return pipe 22a is connected to the oil separator 12
The oil in the oil separator 12a is forcibly returned to the suction pipe of the compressor 11a by opening the on-off valves 23a and 25a.

The forced oil return pipe 22 of the outdoor units 1a and 1b
a and 22b are connected by a balance tube 51. The balance pipe 51 is connected between the oil separator 12a and the check valve 18a through a third auxiliary pipe 53a. The third auxiliary pipe 53a has a third opening / closing valve 55a.
a is provided.

The third on-off valve 55a is opened, and the four-way valve 13a is opened.
Is switched to the illustrated position, the balance pipe 51 communicates with the outdoor heat exchanger 14a.

In the air conditioner having the above configuration, in the present embodiment, the compressors 11a and 11b are driven by the gas engines 100a and 100b, respectively. This compressor 11
The shafts 101a and 101b are led out from the main bodies of the motors a and 11b. Pulleys (not shown) are connected to the shafts 101a and 101b, and the output shafts of the gas engines 100a and 100b are connected via pulley V belts 102a and 102b. Have been.

In the above configuration, during the cooling operation, the refrigerant from the compressors 11a and 11b receives the oil separators 12a and 12b and the four-way valve 13 as indicated by solid arrows in FIG.
a, 13b, the outdoor heat exchangers 14a, 14b, and the outdoor electric expansion valves 15a, 15b, flow out to the liquid pipe 7, enter the indoor units 3a, 3b, and enter the indoor electric expansion valves 35a, 35b.
35b, flows in the order of the indoor heat exchangers 34a, 34b, flows out to the gas pipe 5, and is returned to the compressors 11a, 11b via the four-way valves 13a, 13b and the accumulators 10a, 10b.

In the heating operation, the compressors 11a, 1
As shown by the dotted arrow in FIG. 1, the refrigerant from 1b flows through the oil separators 12a and 12b and the four-way valves 13a and 13b into the gas pipe 5, enters the indoor units 3a and 3b, and enters the indoor heat exchanger. 34a, 34b, the indoor electric expansion valves 35a, 35b flow in order, and flow out to the liquid pipe 7. Further, the outdoor electric expansion valves 15a, 15b, the outdoor heat exchanger 14a,
14b, the four-way valves 13a and 13b, and the accumulators 10a and 10b return to the compressors 11a and 11b.

In this embodiment, the number of operating outdoor units 1a and 1b is controlled so that any one of the outdoor units 1a and 1b is not always operated continuously. The control of the number of operating units is a so-called low tension control, and is controlled by a centralized control device 16 that controls the outdoor units 1a and 1b in an integrated manner.

As shown in FIG. 2, the central control unit 16 includes a central processing unit 107, and the central processing unit 10
7 is connected to a timer 109 for accumulating the cumulative operation time of each of the outdoor units 1a and 1b. Each outdoor unit 1a,
A memory 111 for storing a rated capacity 1b and a target rotation speed described later is connected.

In this embodiment, as shown in FIG.
The compressors 11a and 11b of each outdoor unit 1 include a compressor 11
a, a rotation speed sensor 119a for detecting the rotation speed of 11b,
119b is provided. Further, pressure sensors 117a and 117b are provided for detecting the low-pressure side refrigerant pressure during the heating operation and detecting the high-pressure side refrigerant pressure during the cooling operation. These sensors 117a, 117b, 119
a and 119b transmit the detected data to the central control device 1 via the control lines 115a to 115n, as shown in FIG.
Send to 6. Here, for example, the rated capacity of the outdoor unit 1a is 7.46 kW (10 HP), and the rated capacity of the outdoor unit 1b is 14.92 kW (20 HP).
And so on. Also, the timer 109 and the sensor 1
17a, 117b, 119a and 119b are the outdoor units 1
It is also possible to send data of the accumulated cumulative operation time to the centralized control device 16 via a control line, provided in a or 1b.

The starting order of the outdoor units 1a and 1b is as follows.
First, the one with the shortest cumulative operation time accumulated by the timer 109 is started with priority. If the cumulative operation times are equal, the one with the smaller rated capacity stored in the memory 111 is started with priority.

After the execution of the rotation control, the central control unit 16 controls each compressor 11 according to the air conditioning load.
Loads are distributed to the outdoor units 1 so that the actual rotation speeds of the a and 11b become the same as a target rotation speed described later, and the steady load sharing control is executed.

In this steady load sharing control, the operation status of each outdoor unit 1 differs depending on the surrounding environment where the outdoor unit 1 is installed, and the rotational speed of the compressors 11a and 11b, the refrigerant pressure, etc. The control is such that the rotational speeds and the refrigerant pressures of the compressors 11a and 11b of each outdoor unit 1 are always kept constant even if they differ from each other.

In other words, the steady load sharing control performs a speed balance control for equalizing the actual speeds of the outdoor units 1 and a pressure balance control for equalizing the refrigerant pressure. In this embodiment, the speed balance control is performed. The control is executed with priority, and then the pressure balance control is executed.

Generally, if the number of rotations of the compressor is the same,
The refrigerant pressure at a fixed location of each outdoor unit 1, in this embodiment, the refrigerant pressure detected by the pressure sensors 117 a and 117 b provided between the outdoor heat exchanger that is on the low pressure side during the heating operation and the four-way valve is Should be identical. However, even if the rotation speeds of the compressors 11a and 11b are the same, the detected refrigerant pressure may be different due to a problem such as a clogged pipe. For this reason, in this embodiment, after performing the rotation speed balance control for equalizing the rotation speeds of the compressors 11a and 11b, the pressure balance control for further equalizing the refrigerant pressure is performed.

First, the rotational speed balance control will be described in detail.

In this rotational speed balancing control, the central control device 1
6 is a numerical value required for control, the load factor U _load of each outdoor unit 1
(I) calculating and calculating the rated total capacity Q _all , the surplus load Q _T , the load factor U _{sys of the} device, and the target rotation speed _Ne (i);
When the condition described later is satisfied, the compressor 1 of each outdoor unit 1
Control is performed to adjust the actual rotation speeds of 1a and 11b to the target rotation speed.

The central control unit 16 first calculates the load factor U _load (i) of each outdoor unit 1 based on the equation (1).
The arithmetic expression 1 is described for the i-th outdoor unit when n outdoor units 1 exist. In this equation 1, N _c (i) is the actual number of revolutions (rp) of the outdoor unit (i).
a m), an N _R (i) is the rated speed of the outdoor unit (i) (rpm), H P (i) is the pressure after the matter of the outdoor unit (i), among the ±, + Represents the time of cooling and − represents the time of heating. Bw is the average temperature difference between the indoor outlets.

The load factor U _load (i) is calculated by slightly modifying the ratio of the actual speed to the rated speed. This slight modification and refers acceleration and high pressure after matter portion H _P (i) of the outdoor unit (i), the sum of the indoor discharge difference temperature average Bw.

The high-pressure consequent H _P (i) of the outdoor unit (i) is as follows:
While the ratio of the actual rotation speed to the rated rotation speed is the load factor viewed from the engine side, this load factor
a and 11b to be corrected.
_P (i) indicates that the high-pressure consequent part of the outdoor unit (i) indicates that the actual compressor 11a, 1
The high pressure side pressure 1b is compared with a map pressure stored in an outdoor unit control device (not shown), and is a correction value determined in advance by the result of the comparison. For the map pressure, a standard pressure is determined for the ratio of the actual rotation speed to the rated rotation speed.

The central control unit 16 calculates a rated total capacity Q _all , which is the sum of the rated capacities of the devices, based on equation (2). Q (i) is the rated capacity (kW) of the outdoor unit (i) during operation.

Next, from the rated total capacity Qall and the load factor U _load (i), etc., the surplus load Q _{T of the} apparatus is calculated by the equation (3).
Is calculated based on The surplus load Q _T is obtained by multiplying the rated capacity (kW) of the outdoor unit (i) during operation by the load factor U _load (i), and summing the values obtained by the multiplication to obtain the rated total capacity Qall.
Is subtracted from.

Further, the centralized control device 16 calculates the load factor U _{sys of the} device based on equation (4). The load factor U _sys of this device is a ratio of the capacity obtained by subtracting the surplus load Q _T from the rated total capacity Qall to the rated total capacity Qall.

Then, the centralized control device 16 calculates the target rotational speed N _e (i) from equation (5).

In this embodiment, after the number control (rotation control) is performed, the rotational speed balancing control is executed when the following conditions are satisfied.

In each of the running outdoor units, an equivalent rotation speed, which is a ratio of the actual rotation speed to the rated rotation speed, is calculated, and is executed when the difference between the maximum value and the minimum value of the equivalent rotation speed exceeds 200 rpm. Is done. Compressor 11a of each outdoor unit 1,
The actual rotation speed of 11b is set to the target rotation speed. After this,
Pressure balance control is performed.

Next, the pressure balance control will be described in detail.

After the execution of the rotational speed balance control, for example, as described above, when the compressor 1
Even if the rotation speeds of 1a and 11b are the same, the detected refrigerant pressure may be different, so that the refrigerant pressure is made uniform by this pressure balance control.

In this pressure balance control, the refrigerant pressure detected by pressure sensors 117a and 117b provided in the pipeline between the four-way valves 13a and 13b of each outdoor unit 1 and the outdoor heat exchangers 14a and 14b is as follows. When the condition is satisfied, the control is performed to calculate the fine adjustment rotation speed Δrpm based on the arithmetic expression shown in Expression 6 and finely adjust the rotation speeds of the compressors 11a and 11b to equalize the refrigerant pressure.

In the cooling mode, the pressure sensors 117a,
The pressure difference between the highest pressure and the lowest pressure of the refrigerant pressure on the high pressure side between the operating outdoor units 1 detected by 17b is 0.4 MPa.
Is exceeded, pressure balance control is executed.

In the heating mode, the pressure sensors 117a,
The pressure difference between the maximum pressure and the minimum pressure of the low-pressure side refrigerant pressure between the outdoor units 1 in operation detected by 17b is 0.4 MPa.
Is exceeded, pressure balance control is executed.

This embodiment has the following effects.

The number of operating outdoor units 1 is controlled in accordance with the air-conditioning load, and an equivalent rotation speed, which is a ratio of the actual rotation speed to the rated rotation speed of the outdoor unit 1 being operated, is calculated. The highest rotation speed and the lowest rotation speed are compared, and when the difference between the highest rotation speed and the lowest rotation speed exceeds 200 rpm, the rotation speed balance control is executed. In this rotational speed balancing control, the load factor U _load (i) of each outdoor unit 1 and the rated total capacity Q
_all , excess load Q _T , device load factor U _sys , target speed N _e
(I) is calculated by the centralized control device 16, and the actual rotation speeds of the compressors 11a and 11b of each outdoor unit 1 are made equal to the target rotation speeds. Therefore, the pressure of the refrigerant flowing into and out of the unit-to-unit piping from each outdoor unit 1 Are aligned, driving balance is maintained,
Refrigerant can be prevented from accumulating in the specific outdoor unit 1.

Further, after execution of the rotational speed balance control, the compressor 1
Even if the actual rotation speeds of 1a and 11b are aligned with the target rotation speed,
Pressure equilibrium control is performed on the assumption that there is an outdoor unit 1 in which the refrigerant pressures are not uniform. In this control, the pressure sensor 117a that sets the refrigerant pressure of the operated outdoor unit 1 to the low pressure side during the heating operation and to the high pressure side during the cooling operation,
117b, the maximum pressure and the minimum pressure of the refrigerant pressure are compared, and the deviation between the maximum pressure and the minimum pressure is 0.1.
When the pressure exceeds 4 MPa, the rotational speeds of the compressors 11a and 11b are finely adjusted based on the fine adjustment rotational speed Δrpm calculated by Expression 6 in order to equalize the pressures of the outdoor units 1. The pressure of the refrigerant flowing into and out of the unit-to-unit piping from the outdoor unit 1 is made uniform, the operation balance is maintained, and the refrigerant can be prevented from accumulating in the specific outdoor unit 1.

During the heating operation, the refrigerant pressure on the low pressure side is measured,
Pressure sensors 117a and 117b for measuring the refrigerant pressure
In the cooling operation, the refrigerant pressure on the high pressure side is measured. Therefore, regardless of the heating operation or the cooling operation, each of the outdoor units 1a and 1b has one pressure sensor 117.
The refrigerant pressure can be detected at a and 117b, and there is no need to provide a plurality of measuring instruments, so that the cost can be reduced.

In this embodiment, the rotational speed balance control and the pressure balance control can be realized by using the configuration of a general air conditioner as it is by changing the control method of the central control device 16. For this reason, the development time of the device can be reduced.

The present invention has been described based on one embodiment, but the present invention is not limited to this.

[0056]

The number of rotations between the outdoor units arranged in parallel,
Since the means for equalizing the refrigerant pressure is provided, it is possible to prevent the occurrence of imbalance in the number of revolutions and the refrigerant pressure, and to prevent the refrigerant from accumulating in a specific outdoor unit. Since the control utilizing the property of the air conditioner using the gas engine can be applied to the drive source currently being produced, the development period can be shortened.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an example of an air conditioner according to the present invention.

FIG. 2 is a block diagram illustrating a centralized control device.

[Explanation of symbols]

 1, 1a, 1b Outdoor unit 3a, 3b Indoor unit (load unit) 16 Centralized control device 117a, 117b Pressure sensor 119a, 119b Rotation speed sensor

Continued on the front page (72) Inventor Keiji Wada 2-5-5 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (72) Kazuo Kumehara 2-5-5 Keihanhondori, Moriguchi-shi, Osaka Inside Sanyo Electric Co., Ltd. (72) Akira Shindo 2-5-5 Keihanhondori, Moriguchi City, Osaka Prefecture Inside Sanyo Electric Co., Ltd. (72) Takami Higashi 2-5-5 Keihanhondori, Moriguchi City, Osaka Prefecture No. 5 Sanyo Electric Co., Ltd. (72) Ryota Hirata, Inventor 2-5-5 Keihanhondori, Moriguchi-shi, Osaka Pref. Sanyo Electric Co., Ltd. No.5-5 Sanyo Electric Co., Ltd. F-term (reference) 3L060 AA01 AA08 CC16 CC19 DD02 DD03 EE02 EE09

Claims (6)

[Claims] 1. An air conditioner in which a plurality of outdoor units are connected in parallel to an inter-unit pipe extending from a load unit, a means for controlling the number of the outdoor units to be operated according to an air conditioning load, and a number controlled operation Calculate the ratio of the actual rotation speed to the rated rotation speed of each outdoor unit, compare the highest ratio and the lowest ratio of this ratio, and when the deviation between the highest ratio and the lowest ratio exceeds the specified value. And means for equalizing the ratio of each outdoor unit. 2. An air conditioner in which a plurality of outdoor units are connected in parallel to an inter-unit pipe extending from a load unit, a means for controlling the number of the outdoor units to be operated according to an air conditioning load, and a number controlled operation. The refrigerant pressure of each outdoor unit is measured, and the maximum pressure and the minimum pressure among the refrigerant pressures are compared, and when the deviation between the maximum pressure and the minimum pressure exceeds a specified value, the outdoor unit An air conditioner comprising: means for equalizing pressure; and 3. The air conditioner according to claim 2, wherein the refrigerant pressure on the low pressure side is measured in the heating operation mode. 4. The air conditioner according to claim 2, wherein in the cooling operation mode, the refrigerant pressure on the high pressure side is measured. 5. An air conditioner in which a plurality of outdoor units are connected in parallel to an inter-unit pipe extending from a load unit, a means for controlling the number of the outdoor units to be operated in accordance with an air-conditioning load, and a controlled number of the outdoor units. Calculate the ratio of the actual rotation speed to the rated rotation speed of each outdoor unit, compare the highest ratio and the lowest ratio of this ratio, and when the deviation between the highest ratio and the lowest ratio exceeds the specified value. Means for equalizing the ratio of each outdoor unit, measuring the refrigerant pressure of each outdoor unit that is controlled in number and operating, comparing the highest pressure and the lowest pressure of this refrigerant pressure, Means for equalizing the pressure of each outdoor unit when the deviation from the pressure exceeds a specified value. 6. The means for equalizing the ratio, calculates an individual load factor of each outdoor unit based on the ratio of each outdoor unit, multiplies the rated capacity of each outdoor unit by the individual load factor, and multiplies the multiplied value by the multiplied value. Calculate the surplus load of the outdoor unit under operation control based on the above, subtract the surplus load from the rated total capacity of each outdoor unit, obtain the overall load ratio of all the outdoor units, based on this overall load ratio 6. The method according to claim 1, wherein a target rotation speed of the outside cab unit under operation control is calculated, and the actual rotation speed of the outside cab unit is made uniform so as to match the target rotation speed, and the ratio is made uniform. Air conditioner.