JPH0755269A - Operating control method of air conditioner - Google Patents

Abstract

PURPOSE:To suck oil from other compressors to recover the oil level by interrupting the normal operation to perform an operation which is to produce a differential pressure between closed vessels of compressors. CONSTITUTION:When the operation periods of time of compressor 1, 2 and 3 reach an operation period of time stored in an oil equalizing operation decision device 90, normal operation is interrupted and switched to an oil equalizing operation. The oil equalizing operation instruction is input to a compressor capacity decision device 55 and a normal operation instruction to an inverter 52, on-off switches 53 and 54 is stopped. Simultaneously, the oil equalizing operation decision device 90 outputs an operating frequency instruction for the inverter-controlled compressor 1 to the inverter 52 through an output device 56 so that one among compressors 1, 2 and 3, which requires makeup oil, is operated at a larger capacity than that of the other compressors, and an on-off instruction for the on-off controlled compressors 2 and 3 to the inverter 52 and the on-off switches 53 and 54 through output device 56, 57 and 58. As a result, the compressors 1, 2 and 3 are operated based on the oil equalizing operation program.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an operation control method for an air conditioner in which a plurality of compressors are mounted in one refrigerant system.

[0002]

2. Description of the Related Art An example of a conventional air conditioner is shown in FIGS.
Is shown in.

In FIG. 3, a plurality of (three in the figure) indoor units B1, B2, B3 are connected to an outdoor unit A in parallel via refrigerant pipes. The outdoor unit A includes a plurality of (three in the figure) compressors 1, 2, 3, check valves 4a, 4b, 4c, an outdoor heat exchanger 5, and an accumulator 8.
And so on.

The indoor units B1, B2 and B3 respectively include expansion valves 6a, 6b and 6c and indoor heat exchangers 7a, 7b and 7 respectively.
c is provided. Of the three compressors 1, 2 and 3, one is an inverter control compressor 1 and the other two are on / off control compressors 2 and 3.

An oil separator 10 is provided in the discharge pipe between the discharge port of the inverter-controlled compressor 1 and the check valve 4a, and an oil return pipe 11 extends from this oil separator 10 to the suction pipe of the inverter-controlled compressor 1. Is provided.

The oil separator 2 is connected to the discharge pipe between the discharge ports of the on / off control compressors 2 and 3 and the respective check valves 4b and 4c.
0 and 30 are provided, and oil return pipes 21 and 31 are provided from the oil separators 20 and 30 to the suction pipes of the on / off control compressors 2 and 3, respectively. The closed containers of the three compressors 1, 2 and 3 are connected to each other via an oil equalizing pipe 9. Reference numeral 51 is a power source, and 52 is an inverter.

Incidentally, FIG. 3 shows a refrigerant piping system diagram during the cooling operation, and the illustration of the four-way valve mechanism as seen in the heat pump device is omitted. As shown in FIG. 4, the current from the power supply 51 is supplied to the inverter control compressor 1 via the inverter 52, and the on / off control compressors 2 and 3 are supplied.
Is supplied via the on / off switches 53 and 54. The inverter 52 and the on / off switches 53 and 54 are controlled by the command of the compression function force determination means 55 in the outdoor control device 50, and the outdoor control device 5 is controlled.
The required indoor load is input to 0 as the required indoor frequency for each indoor unit.

During the cooling operation, the gas refrigerant discharged from the compressors 1, 2 and 3 is the oil separators 10, 20, 30 and the check valve 4.
After passing through a, 4b, and 4c, they merge and enter the outdoor heat exchanger 5, where they are condensed and liquefied. This liquid refrigerant is the indoor unit B
1, B2, B3 flow in parallel to the expansion valves 6a, 6b, 6
After adiabatic expansion in c, the indoor heat exchangers 7a, 7b, 7c cool the indoor air to evaporate and vaporize. This gas refrigerant is sucked into the compressors 1, 2 and 3 in parallel via the accumulator 8.

In the oil separators 10, 20 and 30, the lubricating oil (hereinafter abbreviated as oil) contained in the gas refrigerant discharged from the compressors 1, 2 and 3, respectively, is separated, and each oil is separated. It is returned to the inside of the hermetically sealed containers of the compressors 1, 2 and 3 via the return pipes 11, 21 and 31.

The indoor units B1, B2, B3 have indoor control devices 60, 70, 80, and have indoor required frequency determining means 61, 71, 81 therein. These include driving operation units 62, 72, 82 and an indoor temperature sensor 63,
73 and 83 are connected. The indoor required frequency determining means 61, 71, 81 are set indoor temperatures set by the operation operation parts 62, 72, 82 and indoor temperature sensors 63, 73, 83.
The indoor required load is obtained from the detected temperature of, and this is converted into a required frequency and output to the outdoor control device 50.

When the indoor required frequency is input to the compression function force determining means 55 in the outdoor control device 50, the compression function force, that is, the compression function force is calculated based on the control map and the arithmetic expression stored in the compression function force determining means 55. The operating frequency of the inverter control compressor 1 and the ON / OFF control compressors 2 and 3 are determined. The determined operating frequency is output to the inverter 52 via the output means 56, and the inverter-controlled compressor 1 is operated at the determined operating frequency.

The determined on / off command is output to the on / off switches 53 and 54 via the output means 57 and 58 to turn them on or off.

As described above, the operation of the three compressors 1, 2 and 3 is controlled according to the indoor load demand, and the compression capacity is adjusted. An example of the situation is shown in FIG.

The operating frequency of the inverter-controlled compressor 1 is, for example, in the range of 55 Hz to 95 Hz while a plurality of compressors among the compressors 1, 2, 3 are in operation.

[0015]

The conventional method of operating the air conditioner has the following problems to be solved.

That is, in the conventional air conditioner, FIG.
As shown in FIG. 3, when the on / off control compressors 2 and 3 are turned on, the operating frequency of the inverter control compressor 1 changes within a predetermined range, for example, 55 to 95 Hz, and the inverter control compressor 1 performs on / off control. Generally, it is operated at a higher speed than the compressors 2 and 3.

In a compressor of the same type, the OC% (Note 1) of the discharge gas refrigerant generally tends to increase as the rotation speed increases, so that the OC% of the discharge gas refrigerant of the inverter-controlled compressor 1 tends to be higher. Is larger than the OC% of the gas refrigerant discharged from the on / off control compressors 2 and 3.

Note 1: OC% is calculated by the following formula.

OC% = (O / L) × 100
L: amount of discharged refrigerant (g / h) O: amount of oil mixed and discharged in the discharged refrigerant (g / h) On the other hand, since the refrigerant system is one system, the gas refrigerant discharged from each compressor is frozen. Since they are mixed while circulating through the cycle, the OC% of the intake gas refrigerant of each compressor will be approximately equal.

Therefore, in the inverter-controlled compressor 1, the amount of oil that goes out in the refrigeration cycle through the oil separator 10 is generally larger than the amount of oil that circulates in the refrigeration cycle and returns, so that the compressor 1 is hermetically closed. The amount of oil stored in the bottom of the container gradually decreases as the operation continues, and the oil level drops. At this time, if the pressure in the closed container of the inverter-controlled compressor 1 is lower than the pressure in the closed container of the on / off controlled compressors 2 and 3, the oil in the closed container of the on / off controlled compressors 2 and 3 is reduced. Flows through the oil equalizing pipe 9 into the closed container of the inverter-controlled compressor 1 and is replenished, and the oil level in the compressor is restored.

However, in actual operation, the pressure in the closed vessel of the inverter-controlled compressor 1 may be equal to or higher than the pressure in the closed vessel of the on / off control compressors 2 and 3, so the on / off control is performed. The oil in the closed containers of the compressors 2 and 3
It may happen that the oil does not flow into the closed container of the inverter-controlled compressor 1 through the oil equalizing pipe 9. As a result, the oil level in the closed container of the inverter-controlled compressor 1 may be lowered, which may cause lubrication failure of the inverter-controlled compressor 1 or a failure based thereon.

In order to solve the above problems, the present invention is a method for controlling the operation of an air conditioner in which the pressure inside a desired compressor is reduced to a low pressure and oil is sucked from another compressor through an oil equalizing pipe to recover the oil level. The purpose is to provide.

[0023]

The present invention is intended to provide an air conditioner operation control method described in the following (1) and (2) as means for solving the above problems.

(1). In an operation control method of an air conditioner in which a plurality of compressors are connected in parallel to one refrigerant system and each compressor is connected by an oil equalizing pipe, a hermetically sealed container for each compressor at predetermined intervals during normal operation. An operation control method for an air conditioner, which comprises inserting a specific operation that causes a difference in internal pressure.

(2). In the operation control method for an air conditioner according to (1) above, it is possible to insert a specific operation for increasing the capacity of a compressor to be replenished with oil at predetermined intervals during normal operation, which is larger than the capacity of other compressors. A characteristic air conditioner operation control method.

In the above (1) and (2), the "specific operation" means an oil-equalizing operation. That is, it refers to an operation for bringing the lubricating oil level of an arbitrary compressor of the plurality of compressors close to that of other compressors uniformly via the oil equalizing pipe.

[0027]

Since the present invention is constructed as described above, it has the following actions.

(1). In the configuration of the above (1), since a specific operation that causes a difference in the pressure inside the hermetically sealed container of each compressor is inserted at a predetermined interval during the normal operation, each compressor generated during the normal operation is inserted. Before the oil level in the closed container of a compressor reaches the dangerous oil level due to the progress of the imbalance of the oil level in the closed container, the oil level is changed by the specific operation inserted, that is, the oil leveling operation. The pressure in the airtight container of the compressor which is lowered and the oil is desired to be replenished becomes lower than the pressure in the airtight container of another compressor.
As a result, the oil in the airtight container of another compressor flows into the airtight container of the compressor whose oil level is lowered through the oil equalizing pipe, and the oil level in the compressor is restored.

(2). In the configuration of (2) above, in addition to the configuration of (1) above, a compressor for which oil is to be replenished is inserted because a specific operation for making the ability of the compressor to be replenished with oil larger than the ability of another compressor is inserted. The pressure inside the closed container can be selectively made lower than that of the other compressors, and the oil level is restored as in the case of (1) above.

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A method according to an embodiment of the present invention will be described with reference to FIGS.
Will be described.

FIG. 1 is a control block diagram of an air conditioner used in the method of this embodiment, and FIG. 2 is a diagram of its oil-leveling operation program. The refrigerant piping system diagram is the same as that of the conventional example of FIG. 3, and the compressor control diagram is the same as that of each conventional example of FIG.

In the description, the inverter-controlled compressor 1,
The on / off control compressors 2 and 3 should avoid redundancy unless it is necessary to clearly indicate their functions.
They are simply called, for example, "compressor 1" and "compressor 2".

In FIG. 1, the outdoor controller 50 has a built-in oil leveling operation determining means 90. Timers 91, 92, 93 for detecting the operating time of each compressor 1, 2, 3 are connected to the oil-equalization operation determining means 90. Further, the output side is provided with an inverter 52 via output means 56, 57, 58.
And on / off switches 53 and 54.

Other configurations and operations are the same as those of the conventional one shown in FIG. 4, and corresponding members are designated by the same reference numerals and the description thereof will be omitted.

Timers 91, 9 are provided in the oil-equalizing operation determining means 90.
When the operating times of the compressors 1, 2, 3 are input from the compressors 2, 93, the compressors 1, 1 stored in the oil-equalizing operation determining means 90 are stored.
Compared with the conditions of the operation duration of 2 and 3, when the operation duration becomes the stored condition, for example, the compressor 1,
When the cumulative time during which two or more of the two or three units are operated reaches 2 hours, the normal operation is interrupted and it is decided to switch to the oil equalizing operation.

This oil-oil operation switching determination command is input to the compression function force determination means 55, and is then output means 56, 5.
The normal operation command to the inverter 52 and the on / off switches 53 and 54 output via 7, 58 is stopped.

At the same time, the oil leveling operation determining means 90 causes a predetermined oil leveling operation program to make the capacity of one of the compressors 1, 2 and 3 to be replenished with oil larger than the capacity of another compressor. To output the operating frequency command of the inverter control compressor 1 to the on / off control compressors 2 and 3
The OFF command is sent via the output means 56, 57, 58 to the inverter 52 and the ON / OFF switches 53, 5 respectively.
Output to 4.

As a result, the compressors 1, 2 and 3 are operated according to a predetermined oil leveling operation program.

When the operation of each of the compressors 1, 2 and 3 according to the predetermined oil leveling operation program is completed, this end signal is input to the compression function force determining means 55 and the normal operation is restored.

An example of a predetermined oil leveling operation program is shown in FIG. Step 1 is the inverter control compressor 1
Only the highest operating frequency, for example 95 Hz, is run for 3 minutes.
Since the other compressors 2 and 3 are both stopped, the capacity of the inverter-controlled compressor 1 is maximized, so that the pressure in the closed container of the compressor 1 is the pressure in the closed container of the other compressors 2 and 3. The oil level is further lowered and oil is sucked from the other compressors 2 and 3, so that the oil level in the closed container of the compressor 1 is recovered.

In step 2, the inverter control compressor 1 is operated at, for example, 55 Hz, and only the on / off control compressor 2 is operated for 3 minutes. At this time, since the capacity of the on / off control compressor 2 becomes larger than the capacity of the inverter control compressor 1, the pressure in the closed container of the compressor 2 is the pressure in the closed containers of the other compressors 1 and 3. It is further lowered, and the oil level in the closed container of the compressor 2 is recovered.

Similarly, in step 3, the oil level in the closed container of the on / off control compressor 3 is restored, and the oil equalizing operation ends.

In this embodiment, there are three indoor units,
The number of compressors is three, of which one is an inverter control compressor and two are on / off control compressors. However, the number of compressors and the compressor control method are not limited.

Further, the operating frequency of the inverter-controlled compressor 1 in the oil-leveling operation program of FIG. 2 shows the numerical value in this embodiment, and the refrigerant displacement (per rotation) of the three compressors is the present embodiment. If different from the example, the capacity of the compressor whose oil level is to be restored should be made larger than the capacity of other compressors at each step, and the operating frequency of the inverter-controlled compressor will be reset naturally.

In this embodiment, the steps are 1 → 2 → 3.
However, the order is not limited.

As described above, according to this embodiment, the compressor 1,
Regardless of which of the two or three becomes short of oil, the capacity of the compressor can be selectively made larger than that of the other compressors, so that the pressure in the hermetically sealed container of the compressor is different from that of the other compressors. There is an advantage that the oil level of the other compressor is lowered, the oil of another compressor flows into the compressor through the oil equalizing pipe, the oil level is recovered, and the concern of poor lubrication or failure due to it is eliminated.

[0047]

Since the present invention is constructed as described above, it has the following effects.

That is, according to the present invention, the imbalance of the oil level in the closed container of each compressor caused by the normal operation continuation progresses, and the oil level in the closed container of a certain compressor reaches the dangerous oil level. Before the normal operation is switched to a specific operation, that is, the oil-equalizing operation, the oil level is lowered by the oil-equalizing operation, and the pressure in the closed container of the compressor to which oil is to be replenished is kept in the closed container of another compressor The pressure can be lower than the pressure.

As a result, the oil in the airtight container of another compressor having a relatively high pressure flows into the airtight container of the compressor whose oil level is lowered through the oil equalizing pipe, and the oil in the air compressor Since the surface is restored, it is possible to avoid poor lubrication due to a decrease in the oil level of the compressor or a failure based on this.

[Brief description of drawings]

FIG. 1 is a control block diagram according to a method of an embodiment of the present invention,

FIG. 2 is a diagram of an oil leveling operation program of the above embodiment,

FIG. 3 is a refrigerant circuit diagram of a conventional air conditioner,

FIG. 4 is a control block diagram of a conventional air conditioner,

FIG. 5 is a diagram showing control of a compressor according to a relationship between a load and a compression capacity of a conventional air conditioner.

[Explanation of symbols]

 1 Inverter control compressor 2, 3 ON / OFF control compressor 9 Oil leveling pipe 90 Oil leveling operation determining means 91, 92, 93 Timer

Claims (2)

[Claims] 1. An operation control method for an air conditioner, comprising a plurality of compressors connected in parallel to one refrigerant system and each compressor connected by an oil equalizing pipe. An operation control method for an air conditioner, characterized by inserting a specific operation that causes a difference in pressure in a closed container of a compressor. 2. The operation control method for an air conditioner according to claim 1, wherein a specific operation for increasing the capacity of the compressor to be replenished with oil at a predetermined interval during normal operation is made larger than the capacity of other compressors. An operation control method for an air conditioner, which is characterized in that the air conditioner is inserted.