JP3341495B2 - Operation control device for air conditioner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an operation control device for an air conditioner, and more particularly to an improvement in protection measures for a wet operation of a compressor.

[0002]

2. Description of the Related Art Conventionally, for example, Japanese Patent Laid-Open No.
As disclosed in Japanese Unexamined Patent Publication No. 2 (KOKAI), a refrigerant circuit provided in an air conditioner includes a compressor. This compressor sucks the gas refrigerant evaporated in the evaporator, compresses the gas refrigerant to a high temperature and a high pressure, and discharges the compressed gas refrigerant to the condenser.

[0003] Further, in the operation of such a compressor, in an operation state in which the refrigerant is not sufficiently evaporated (for example, during a defrost operation or a low outside air heating operation), a liquid phase remains in a part of the refrigerant. A so-called wet operation state, in which the compressor is sucked into the compressor as it is, is likely to occur, and at this time, the operation of the compressor may be hindered by diluting the lubricating oil stored in the compressor.

[0004] Therefore, in a situation where such a wet operating state is likely to occur, the compressor is operated at a low rotation speed to suppress the suction of the liquid refrigerant into the compressor. For example, during the defrost operation, the rotation speed is regulated to a predetermined value or less until the defrost operation is completed.

[0005] In addition to the defrost operation and the low outside air heating operation, even when the liquid refrigerant is stored in the accumulator at the time of restart after the stop of the heating operation, this liquid is not affected. Refrigerant may be introduced into the compressor to cause the above-described problem.

Hereinafter, the operation of setting the number of revolutions of the compressor during the defrost operation in the refrigerant circuit including the compressor controlled by the inverter (operating frequency range 30 Hz to 116 Hz) and the compressor switched ON / OFF. An example will be described. First, the frequency of the inverter compressor is set to 38 Hz and the ON / OFF compressor is turned on for a period of 30 seconds from the start of defrost. During the period from the lapse of 30 seconds to the end of the defrost slot, the frequency of the inverter compressor is limited to 86 Hz to suppress the occurrence of the wet operation state, and the ON / OFF compressor is turned on. Further, the frequency of the inverter compressor is set to 60 Hz and the ON / OFF compressor is turned off for a period of 3 minutes from the end of defrost. afterwards,
The frequency of the inverter compressor is set to 116 Hz, the ON / OFF compressor is turned off, and this state is set to 20 mi after the end of the defrost slot.
After the suction of the liquid refrigerant at the time of returning to the heating is suppressed by continuing the process until n elapses, the regulation of the rotational speed of the compressor is released to return to the normal heating operation.

[0007]

As described above, in the related art, in the operation mode in which a wet state is easily generated, the rotation speed of the compressor is set in a fixed pattern. In other words, even when the operating state of the compressor is not the wet operating state, since the rotational speed of the compressor is limited, the operating state in which the compressor can be rotated at a high speed to exhibit sufficient capacity is originally provided. Nevertheless, the control was made to make this impossible.

[0008] The present invention has been made in view of this point, and by setting the number of rotations according to the wet operating state of the compressor, the number of rotations within a range that does not hinder the operation of the compressor. The purpose is to fully demonstrate their abilities.

[0009]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention determines a wet operation state of a compressor and operates the compressor at a low capacity when the compressor is in a wet operation state and at a high capacity when it is not. In this way, the air conditioning capacity in the non-wetting operation state is sufficiently exhibited.

Specifically, as shown in FIG. 1, the invention according to claim 1 has a compressor (1) having a variable capacity and a heat source side heat exchanger (6).
The refrigerant circulation circuit (14), in which the pressure reduction mechanisms (8), (13) and the use-side heat exchanger (12) are sequentially connected so that the refrigerant can circulate, and the cycle of the refrigerant circulation circuit (14) are cooled and removed. It is assumed that the air conditioner includes a four-way switching valve (5) that can be switched between a frost operation cycle and a heating operation cycle. And a compressor capacity limiting means (15a) for limiting the capacity of the compressor (1) to a predetermined low value during the defrosting operation; and a refrigerant circulation state in the refrigerant circulation circuit (14) during the defrosting operation. Receives the outputs of the wetness determining means (15b) for detecting that the liquid refrigerant is introduced into the compressor (1) and the output of the wetness determining means (15b), and When the liquid refrigerant is introduced into the compressor (1), while the capacity of the compressor (1) is permitted by the compressor capacity limiting means (15a), when the liquid refrigerant is not introduced into the compressor (1), The compressor capacity limiting means (1
5a) to release the capacity limitation of the compressor (1)
The compressor capacity adjusting means (15c) for setting the capacity of (1) higher than the predetermined value is provided.

Further, the invention according to claim 1 includes a refrigerant circulation amount changing means (13 ') provided in the refrigerant circulation circuit (14) for varying the refrigerant circulation amount, and a compressor (1') during the defrosting operation. ) Wet time measuring means (15d) for measuring the wet time in which the liquid refrigerant remains inside, and the output from the wet time measuring means (15d), and the wet time is measured during the defrosting operation and during the previous defrosting operation. Refrigerant circulation amount adjusting means (1) for adjusting the refrigerant circulation amount changing means (13 ') so that the shorter the wet time measured by the time measuring means (15d) becomes, the larger the refrigerant circulation amount in the refrigerant circulation circuit (14) becomes.
5e).

[0012] According to a second aspect of the invention, the operation control device for air conditioner according to the first aspect, the compressor (1),
Oil temperature detecting means (Tho) for detecting the temperature of the lubricating oil stored in the compressor (1) is provided. Also, the wetness determining means
(15b) is a state in which liquid refrigerant is introduced into the compressor (1) by comparing the oil temperature detected by the oil temperature detection means (Tho) with the refrigerant temperature on the compressor suction side. Is determined.

According to a third aspect of the present invention, as shown in FIG. 1, a variable capacity compressor (1), a heat source side heat exchanger (6), pressure reducing mechanisms (8), (13) and a use side heat exchange Circuit (14), in which a unit (12) is connected in order to enable refrigerant circulation, and a four-way switchable cycle for switching the cycle of the refrigerant circuit (14) between a cooling and defrosting operation cycle and a heating operation cycle. An air conditioner equipped with a valve (5) is assumed. And a compressor capacity limiting means (15a) for limiting the capacity of the compressor (1) to a predetermined low value during the defrosting operation; and a refrigerant circulation circuit (14) during the defrosting operation.
Receiving the outputs of the wetness determining means (15b) and the wetness determining means (15b) for detecting that the refrigerant is circulated in the compressor (1) in a state in which the liquid refrigerant is introduced into the compressor (1). When the liquid refrigerant is introduced into the compressor (1), the capacity of the compressor (1) is permitted by the compressor capacity limiting means (15a), while the liquid refrigerant is introduced into the compressor (1). If not, the compressor capacity limiting means (15a) releases the capacity limitation of the compressor (1) and sets the capacity of the compressor (1) higher than the predetermined value.
(15c).

Further, the invention according to claim 3 is a compressor (1)
Further, oil temperature detecting means (Tho) for detecting the temperature of the lubricating oil stored inside the compressor (1) is provided. Further, the wetness judging means (15b) compares the oil temperature detected by the oil temperature detecting means (Tho) with the refrigerant temperature on the compressor suction side, so that the liquid refrigerant is introduced into the compressor (1). Is determined.

A fourth aspect of the present invention is a compressor having a variable capacity.
(1) a refrigerant circulation circuit (14) in which a heat source side heat exchanger (6), a pressure reducing mechanism (8), (13) and a use side heat exchanger (12) are connected in order so that refrigerant can circulate, It is premised on an air conditioner having a four-way switching valve (5) capable of switching the cycle of the refrigerant circuit (14) between a cooling and defrosting operation cycle and a heating operation cycle. And a compressor capacity limiting means (15a) for limiting the capacity of the compressor (1) to a predetermined value of a low capacity when returning to the heating operation after the completion of the defrosting operation;
Wet determination means (15b) for detecting that the circulation state of the refrigerant in (14) is in a state in which the liquid refrigerant is introduced into the compressor (1), and an output of the wetness determination means (15a). received,
When liquid refrigerant is introduced into the compressor (1),
While the capacity of the compressor (1) is allowed to be limited by the compressor capacity limiting means (15a), the compressor (1) is operated at the predetermined low capacity for a predetermined time, while the compressor (1) has a liquid inside the compressor (1). When the refrigerant is not introduced, the compressor capacity regulating means (15
a) a compressor capacity adjusting means (15c) for canceling the capacity limitation of the compressor (1) according to (a).

Further, the invention according to claim 4 is a compressor (1)
Further, oil temperature detecting means (Tho) for detecting the temperature of the lubricating oil stored inside the compressor (1) is provided. Further, the wetness judging means (15b) compares the oil temperature detected by the oil temperature detecting means (Tho) with the refrigerant temperature on the compressor suction side, so that the liquid refrigerant is introduced into the compressor (1). Is determined.

According to a fifth aspect of the present invention, there is provided a compressor having a variable capacity.
(1), a heat source side heat exchanger (6), a decompression mechanism (8), and a refrigerant circulation circuit (14) in which the use side heat exchanger (12) is connected in order to allow refrigerant circulation. Air conditioner is assumed. And a wetness determining means (15b) for detecting that the state of circulation of the refrigerant in the refrigerant circuit (14) is in a state in which the liquid refrigerant is introduced into the compressor (1); and When the output of (15b) is received and the compressor stop condition is satisfied, and the liquid refrigerant is introduced into the compressor (1), the capacity of the compressor (1) is reduced to a level that prevents the introduction of liquid refrigerant. While operating the compressor (1) for a predetermined time while limiting the capacity,
When no liquid refrigerant is introduced into the compressor (1), the compressor capacity adjusting means (1) enables the compressor (1) to be stopped.
5c).

Further, according to a fifth aspect of the present invention, the compressor (1)
Further, oil temperature detecting means (Tho) for detecting the temperature of the lubricating oil stored inside the compressor (1) is provided. Further, the wetness judging means (15b) compares the oil temperature detected by the oil temperature detecting means (Tho) with the refrigerant temperature on the compressor suction side, so that the liquid refrigerant is introduced into the compressor (1). Is determined.

[0019]

According to the above construction, the following effects can be obtained in the present invention.

According to the first and third aspects of the present invention, during the defrosting operation, the state of circulation of the refrigerant in the refrigerant circuit (14) is determined by the wetness judging means (15b) inside the compressor (1). If it is determined that the refrigerant is being introduced, the compressor capacity adjusting means (15c)
a), the capacity of the compressor (1) is limited to a low, predetermined value by restricting the capacity of the compressor (1), the introduction of liquid refrigerant to the compressor (1) is suppressed, and wet operation is performed. Be avoided. On the other hand, when it is determined that the liquid refrigerant is not introduced into the compressor (1), the compressor capacity adjusting means (15c) restricts the capacity of the compressor (1) by the compressor capacity limiting means (15a). Then, the capacity of the compressor (1) is set higher than the predetermined value. As a result, the defrosting ability in the non-wet operation state is improved.

Further, according to the present invention, when the defrosting operation is performed, the wet time measuring means (15d) measures the wet state time during the defrost operation. When the defrosting operation is performed again after the defrosting operation is completed, the refrigerant circulation amount adjusting means (15e) changes the refrigerant circulation amount according to the wet state time during the previous defrost operation. Means (1
3 ') is adjusted to adjust the amount of refrigerant circulating in the refrigerant circuit (14). In this adjustment, the shorter the wet state time during the previous defrosting operation, the larger the refrigerant circulation amount, so that the defrosting capacity can be reduced while avoiding the introduction of the liquid refrigerant to the compressor (1). Is improved.

According to the second and third aspects of the present invention, the compressor (1) detected by the oil temperature detecting means (Tho)
The wet operating state of the compressor (1) is determined based on the lubricating oil temperature in the inside. Thereby, the wetness determination can be accurately performed.

According to the fourth aspect of the present invention, at the time of heating recovery after the completion of the defrosting operation, the capacity of the compressor (1) is adjusted by the compressor capacity adjusting means (15c) in accordance with the wet operation state of the compressor. On the other hand, when the operation is not in the wet operation state, by releasing the restriction on the capacity of the compressor (1), the rising performance at the time of returning to heating after the end of defrosting is improved.

According to the fifth aspect of the present invention, when the condition for stopping the compressor (1) is satisfied and the liquid refrigerant is being introduced into the compressor (1), the compressor is kept at a low capacity for a predetermined time.
By operating (1), the storage of the liquid refrigerant on the compressor suction side is avoided, and the liquid refrigerant is prevented from being introduced into the compressor (1) at startup.

Further, in the invention according to the fourth and fifth aspects, the compressor (1) detected by the oil temperature detecting means (Tho)
The wet operating state of the compressor (1) is determined based on the lubricating oil temperature in the inside. Thereby, the wetness determination can be accurately performed.

[0026]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 shows a refrigerant piping system of the outdoor unit (A) of the multi-type air conditioner according to this embodiment. Although not shown, the outdoor unit (A) includes a plurality of indoor units (B),
(B), ... are connected in parallel with each other. Each indoor unit (B) has basically the same configuration, and FIG. 3 shows a refrigerant piping system of one indoor unit (B).

In the outdoor unit (A), the capacity is adjusted by an inverter (2a) whose output frequency is variably switched every 4 to 10 Hz within a range of 30 to 116 Hz.
A variable capacity compressor (1) configured by connecting a compressor (1a) and a second compressor (1b) whose operation stop is switched according to the level of pilot pressure in parallel via a check valve (1e). ) And the first,
Oil separators (4a) and (4b) for separating oil in gas discharged from the second compressors (1a) and (1b), respectively. A four-way switching valve (5) that switches as indicated by a broken line, an outdoor heat exchanger (6) that becomes a condenser during cooling operation, and an evaporator during heating operation, and the outdoor heat exchanger
The two outdoor fans (6a) and (6b) attached to (6), the outdoor electric expansion valve (8) that adjusts the refrigerant flow rate during the cooling operation, and performs the throttling operation of the refrigerant during the heating operation, and liquefied. A receiver (9) for storing the refrigerant and an accumulator (10) are incorporated as main devices, and each of the devices (1) to (10) is connected so that the refrigerant can flow through a refrigerant pipe (11). ing.

The indoor unit (B) includes an indoor heat exchanger (12) that functions as an evaporator during a cooling operation and a condenser during a heating operation, and a fan (12a) for the indoor heat exchanger (12). On the liquid pipe side, an indoor electric expansion valve that adjusts the refrigerant flow rate during the heating operation and performs the throttle function of the refrigerant during the cooling operation
(13) is interposed. And each indoor unit (B),
After the refrigerant pipes of (B), ... merge, the manual shut-off valves (17a), (1
The outdoor unit is connected by connecting pipes (11a) and (11b) via 7b).
(A). That is, the above devices are connected by a refrigerant pipe (11) through which refrigerant can flow, and the main refrigerant circuit (14) is configured to release heat obtained by heat exchange with outdoor air to indoor air. Is configured.

Further, (40) is a liquid injection bypass passage for injecting liquid refrigerant into the suction line during cooling / heating operation to adjust the degree of superheat of the suction gas. The liquid injection bypass passage (40) Each compressor
It branches into branch pipes (40a) and (40b) connected to the suction portions of (1a) and (1b). And, in each of the branch pipes (40a), (40b),
Capillary tubes (41a) and (41b) and injection solenoid valves (42a) and (42b) that open when the discharge pipe temperature rises excessively
And each is interposed.

Further, (31) cools the suction refrigerant by heat exchange between the suction refrigerant in the suction pipe (11) and the liquid refrigerant in the liquid pipe (11), and superheats the refrigerant in the communication pipe (11b). It is a suction pipe heat exchanger for compensating for the rise in temperature.

The apparatus is provided with a number of sensors, (Th1) is a room temperature thermostat for detecting each room temperature, and (Th2) and (Th3) are liquids of the indoor heat exchanger (12). Liquid temperature sensor and indoor gas temperature sensor for detecting the temperature of the refrigerant in the side and gas side pipes, (Th4a) and (Th4b) are discharge pipe sensors for detecting the discharge pipe temperature of each compressor (1a) and (1b) (Th5) is a defrost sensor that detects the state of frost from the outlet temperature of the outdoor heat exchanger (6) during the heating operation, and (Th6) is a sensor connected to the suction pipe (11) downstream of the suction pipe heat exchanger (31). Placed,
An intake pipe sensor that detects the intake pipe temperature, (Th7) is located at the air inlet of the outdoor heat exchanger (6), and an outside air temperature sensor that detects the intake air temperature, and (Tho) is the first compressor (1a) An oil temperature sensor that detects the temperature of the lubricating oil stored inside is installed in the discharge pipe, and the main refrigerant circuit (14)
Is a high-pressure sensor that detects the high-pressure side pressure, and (P2) is a low-pressure sensor that is disposed in the suction line and detects the low-pressure side pressure.

The outdoor unit (A) is provided with auxiliary devices in addition to the above main devices. (twenty one)
Is connected to a pressure equalizing hot gas bypass passage (11d) connecting the discharge pipe (1h) on the first compressor (1a) side and the suction side of the compressor. (33a), (33b) solenoid valves for pressure equalization that open for a fixed time before restarting when stopped
Are oil return pipes for returning lubricating oil from the oil separators (4a) and (4b) to the first and second compressors (1a) and (1b) via capillary tubes (32a) and (32b), respectively. It is.

Further, an equalizing passage (30) is provided between the receiver (9) and the equalizing hot gas bypass passage (11d). One end of the pressure equalizing path (30) is connected to the upper end face of the receiver (9), and the other end is located upstream of the pressure equalizing solenoid valve (21) of the pressure equalizing hot gas bypass path (11d). Connected, from receiver (9) to pressure equalizing hot gas bypass (11d)
Check valve (3) to allow only refrigerant flow in the direction
0a) is interposed. With this configuration, when the equalizing solenoid valve (21) is open, the gas refrigerant in the receiver (9) can be introduced into the equalizing hot gas bypass passage (11d), and eventually into the suction side of the compressor (1). Thus, pressure equalization of the entire circuit is performed.

(22) is an oil recovery passage (11e) connecting the upstream side of the capillary tube (32a) in the oil return pipe (33a) on the first compressor (1a) side and the compressor suction side. This is an interposed solenoid valve. As a result, the lubricating oil recovered in the oil separator (4a) is returned from the oil return pipe (33a) to the compressor (1) through the oil recovery path (11e) during the above-mentioned equalizing operation. It is supposed to be.

In the figure, (HPS) is a high-pressure switch for protecting the compressor, and (GP) is a gauge port.

The above-mentioned solenoid valves and sensors are connected to the control unit (15) together with the main equipment by signal lines, and the control unit (15) receives the signals from the sensors and sends the signals to the electric valves and solenoid valves. Control of the compressor and the capacity of the compressor.

Each compressor (1) is constructed by a so-called forced differential pressure system. That is, the suction pipe (1d) of the second compressor (1b) whose drive and stop are switched is connected to the middle of the suction pipe (1c) of the first compressor (1a) whose capacity is adjusted by the inverter (2a). In addition, the diameter of the suction pipe (1d) of the second compressor (1b) is set to be smaller than the diameter of the suction pipe (1c) of the first compressor (1a). ), The pressure loss of the suction pipe (1d) of the first compressor (1a) is made larger than the pressure loss of the suction pipe (1c) of the first compressor (1a). The compressors (1b) are configured on the lower dome side, respectively. In addition, the first compressor (1a) and the second compressor (1b) are connected by an oil equalizing pipe (1f) provided with a capillary (1g), so that the lubricating oil stored inside can be distributed. I have to. As a result, during operation of both compressors (1a) and (1b), a pressure difference is generated inside each of the compressors (1a) and (1b) due to the difference in pressure loss, and the first compressor (1
a) The internal lubricating oil is supplied to the second compressor (1b) via the oil equalizing pipe (1f), whereby each compressor (1a), (1b)
The amount of oil is substantially uniform.

As shown in FIG. 2, the control unit (15) includes a compressor capacity limiting means (15a), a wetness judging means.
(15b), compressor capacity adjusting means (15c), wet time measuring means
(15d), a refrigerant circulation amount adjusting means (15e) is provided.

The compressor capacity limiting means (15a) limits the capacity of the compressor (1) to a predetermined low capacity value at the time of defrost operation, at the time of heating operation return after the end of the defrost operation, at the time of low outside air heating operation, and the like. Specifically, for example, during the defrost operation, the operating frequency of the first compressor (1a) is set to 8
At 6 Hz, the second compressor (1b) is turned on.

The wetness judging means (15b) detects that the state of circulation of the refrigerant in the main refrigerant circuit (14) is such that liquid refrigerant is introduced into the compressor (1). Specifically, the determination is made by comparing the oil temperature detected by the oil temperature sensor (Tho) with the refrigerant temperature Te on the compressor suction side detected by the suction pipe sensor (Th6).

The compressor capacity adjusting means (15c) includes a compressor (1)
When the liquid refrigerant is introduced into the compressor, the capacity of the compressor (1) is allowed to be limited by the compressor capacity limiting means (15a), while when the liquid refrigerant is not introduced into the compressor (1). The capacity limitation of the compressor (1) by the compressor capacity limitation means (15a) is released, and the capacity of the compressor (1) is set higher. Specifically, for example, when the liquid refrigerant is not introduced into the compressor (1) during the defrost operation, the operating frequency of the first compressor (1a) is set to 1
06 Hz, and the second compressor (1b) is turned on.

The wet time measuring means (15d) measures the wet time during which the liquid refrigerant remains inside the compressor (1) during the defrost operation.

During the defrost operation, the refrigerant circulation amount adjusting means (15e) controls the refrigerant in the refrigerant circulation circuit (14) as the wet state time measured by the wet time measuring means (15d) during the previous defrost operation becomes shorter. The opening degree of the indoor electric expansion valve (13) is set to be large so that the circulation amount increases.

Next, the operation of the air conditioner configured as described above will be described. 2 and 3,
During the cooling operation of the air conditioner, the four-way switching valve (5) switches to the solid line side in the figure, the refrigerant compressed by the compressor (1) is condensed in the outdoor heat exchanger (6), and the communication pipe (11a ) And is sent to each indoor unit (B), (B),... Each indoor unit
In (B), (B), ..., the pressure is reduced by each indoor electric expansion valve (13), ..., and after evaporating in each indoor heat exchanger (12), ..., they are combined and gas is sent to the outdoor unit (A). It returns in the state and circulates so as to be sucked into the compressor (1). That is, the liquid refrigerant is supplied to the indoor heat exchanger (1
In 2), the indoor air is cooled by performing heat exchange with the indoor air and evaporating.

In the heating operation, the four-way switching valve (5) is switched to the broken line in the drawing, and the flow of the refrigerant is reversed from that in the cooling operation, and the refrigerant compressed by the compressor (1) is discharged. After being condensed in the indoor heat exchangers (12), ..., merge and flow in a liquid state to the outdoor unit (A), decompressed by the outdoor electric expansion valve (8), and evaporated in the outdoor heat exchanger (6) Circulates back to compressor (1). That is, the gas refrigerant heats the indoor air by performing heat exchange with the indoor air in the indoor heat exchanger (12) and condensing. If the outdoor heat exchanger (6) becomes frosted during the heating operation, the operation is switched to the defrost operation, the four-way switching valve (5) becomes the solid line side in the figure, and the electric expansion valves (8), (13) Is fully opened and defrosted by the high-temperature refrigerant discharged from the compressor (1).

In such a driving operation, when both compressors (1a) and (1b) are driven, the second
The pressure loss of the suction pipe (1d) of the compressor (1b) is larger than the pressure loss of the suction pipe (1c) of the first compressor (1a). , (1b) a pressure difference occurs inside the first compressor (1a), and the lubricating oil inside the first compressor (1a) is supplied to the second compressor (1b) through the oil equalizing pipe (1f), whereby each compressor (1a) ,
(1b) The amount of lubricating oil inside is substantially equalized.

The operation of this embodiment is as follows.
The operation capacity (rotation speed) of the compressor (1) during the defrost operation is being set. Hereinafter, an example of the operation for setting the number of revolutions of the compressor (1) will be described with reference to the flowcharts of FIGS.

When the outdoor heat exchanger (6) is frosted during the heating operation, the mode is switched to the defrost operation when the outlet temperature of the outdoor heat exchanger (6) detected by the defrost sensor (Th5) drops below a predetermined value. First, in step ST1, the lubricating oil temperature To inside the first compressor (1a) detected by the oil temperature sensor (Tho) is increased by 10 ° C. to the suction pipe temperature Te detected by the suction pipe sensor (Th6). Is determined by the wetness determining means (15b) as to whether or not the value is equal to or less than the value obtained by adding. This is an operation for determining whether or not the compressor (1) is in the wet operation state based on the lubricating oil temperature To.
In the case of YES, the lubricating oil temperature To is determined to be in the wet operating state because it is relatively low, while in the case of NO, the lubricating oil temperature To is determined to be not in the wet operating state because it is relatively high. In this determination, the suction pipe temperature Te is set to 10 ° C.
The reason why was added was that considering the variation in the detection accuracy of the sensors (Tho) and (Th6) and the ambient temperature inside the compressor, the range of judging the wet operating condition was expanded to ensure the protection of the compressor (1). To do it. If the determination in step ST1 is YES, the process proceeds to step ST2, in which the operation frequency of the first compressor (1a) is set to 38 Hz as a preparation operation for the defrost operation.
The state where the second compressor (1b) is ON is set as the upper limit of the capacity of the compressor (1). In other words, the compressor (1)
(For example, when the operating frequency of the first compressor (1a) is 38 Hz, the second compressor (1b) is ON, and the operating frequency of the first compressor (1a) is 1
Only the second compressor (1b) is turned off at 00Hz).
This is an operation for setting the number of revolutions of the compressor (1) low to avoid the introduction of the liquid refrigerant at the start of defrost. Further, as another preparatory operation for the defrost operation, the stop of the indoor fan (12a) is performed at the same time.

After this preparatory operation, when the four-way switching valve (5) is switched to the cooling operation side and the defrost operation is started,
First, in step ST3, the opening pulse of the indoor electric expansion valve (13) is set to a relatively large value of 1000 PLS.
In step ST4, 3 is set by a timer provided in advance.
It is determined whether 0 seconds have elapsed. And 30sec
After elapses, the process proceeds to step ST5 where the operating frequency of the first compressor (1a) is set to 86 Hz, and the second compressor (1b) is turned on.
That is, since it is determined in step ST1 that the compressor (1) is in the wet operating state, the compressor capacity adjusting means (15c) allows the capacity limitation by the compressor capacity limiting means (15a). In this way, the introduction of the liquid refrigerant into the compressor (1) is suppressed by preventing the rotation speed of the compressor (1) from rapidly increasing.

On the other hand, if the determination in step ST1 is NO, the same operation as in step ST2 described above is performed as a preparatory operation for the defrost operation in step ST6.
When the defrost operation is started, the above-described step ST
The same operations as in steps 3 and 4 are performed in steps ST7 and ST8. If it is determined in step ST8 that 30 seconds have elapsed, the process proceeds to step ST9 where the first compressor (1a)
And the second compressor (1b) is turned on. That is, in step ST1 described above, the compressor
(1) is determined not to be in wet operation,
Even if the rotation speed of the compressor (1) is set relatively high,
Since the liquid refrigerant is not introduced into (1), the compressor capacity adjusting means (15c) is used to increase the defrost operating capacity within a range that does not hinder the operation of the compressor (1).

During each of the above-described defrosting operations, at step ST10, the low-pressure side pressure of the compressor suction side is reduced.
If LP is detected by the low pressure sensor (P2) and the low pressure side pressure LP becomes lower than 0.1 kg / cm ² , the operation frequency of the first compressor (1a) is set to 8 in step ST11.
At 6 Hz, the second compressor (1b) is turned off to reduce the rotation speed of the compressor (1), thereby suppressing the lowering of the low pressure side pressure LP.

When the defrost operation is performed for a predetermined time and the outlet temperature of the outdoor heat exchanger (6) detected by the defrost sensor (Th5) rises to a predetermined value, the end determination of the defrost is made in step ST12. Then, the four-way switching valve (5) is switched to return to the normal heating operation.

In this return operation, first, in step ST13
In FIG. 5, the operating frequency of the first compressor (1a) is 60 Hz.
Then, the second compressor (1b) is turned off, and if it is determined in step ST14 that 3 minutes have elapsed, the operation frequency of the first compressor (1a) is 116 Hz and the second compressor (1b) is turned on in step ST15. The OFF state is the upper limit of the capacity of the compressor (1). In other words, in this return operation, the rotation speed of the compressor (1) is gradually increased, and even when liquid refrigerant is accumulated in the accumulator (10), the liquid refrigerant is introduced into the compressor (1). Have been avoided.

Thereafter, in step ST16, the lubricating oil temperature To is again compared with a value obtained by adding 10 ° C. to the suction pipe temperature Te by the wetness judging means (15b), and the lubricating oil temperature To is reduced by 10 ° C. to the suction pipe temperature Te. Is greater than or equal to the sum of the compressor (1), or if 20 minutes have elapsed since the end of the defrost operation, the compressor (1) as described above in steps ST17 and ST18.
The restriction on the operating state is released to return to the normal heating operation. In other words, the compressor capacity adjusting means (15c) delays the return to the normal heating operation (20 min delay) when the lubricating oil temperature To is relatively low, because the wet operation state is established.
After returning to normal heating operation after canceling the wet operation state, if the lubricating oil temperature To is relatively high, the operation is not in the wet operation state, so the restriction on the operating state of the compressor (1) is released and the normal heating operation is immediately performed. Return to As a result, the room's rapid warming performance is improved without hindering the operation of the compressor (1).

As described above, according to the operation of the present embodiment, the compressor
(1) The upper limit capacity should be changed according to the wet operating condition of (1).
Since (1) is set to high rotation so that its performance can be fully demonstrated, it is compared with the conventional method in which the rotation speed of the compressor (1) is set in a fixed pattern regardless of the wet operation state. The air conditioner performance can be improved without hindering the operation of the compressor (1).

(First Modification) Next, a modification of the rotation speed setting operation of the compressor (1) during the defrost operation will be described with reference to the flowcharts of FIGS. In the operation of the present example, the operations of steps ST21 to ST39 in FIGS. 6 and 7 are substantially the same as the operations of steps ST1 to ST18 of the above-described embodiment, and are performed when the compressor (1) is in the wet operation state. Since the rotation speed of the compressor (1) and the defrost end time during the defrost operation are changed accordingly, the description is omitted here.
The operation after step ST39 will be described.

First, after returning to the normal heating operation in step ST39, the process proceeds to step ST40 to determine whether or not the accumulated operation time of the compressor (1) since the end of the defrost operation has become 30 minutes or more, that is, during the heating operation. It is determined whether or not the integrated time of the thermo-on time has become 30 min or more. If the determination is YES here, step ST4
1 (FIG. 8), it is determined whether or not the state in which the outlet temperature Tb of the outdoor heat exchanger (6) detected by the defrost sensor (Th5) is equal to or lower than the predetermined frost determination temperature Tdef has continued for 5 minutes. If the answer is YES, the four-way switching valve (5) is switched and the operation shifts to the defrost operation again.

In the operation at this time, first, in step ST42, the lubricating oil temperature To inside the first compressor (1a) detected by the oil temperature sensor (Tho) is detected by the suction pipe sensor (Tho).
It is determined whether the temperature is equal to or less than a value obtained by adding 10 ° C. to the suction pipe temperature Te detected in h6). This is an operation for determining whether or not the compressor (1) is in the wet operating state based on the lubricating oil temperature To, as in the case of the above-described embodiment. While it is determined that the vehicle is in the operating state, if NO, it is determined that the vehicle is not in the wet operating state. If YES is determined in step ST42, the indoor electric expansion valve (1) is determined in step ST43.
3) The opening pulse is set to 500 PLS, and the process proceeds to step ST44, where the operating frequency of the first compressor (1a) is 38 Hz.
The state where the second compressor (1b) is ON is set as the upper limit of the capacity of the compressor (1). This is an operation for setting the number of revolutions of the compressor (1) low to avoid the introduction of the liquid refrigerant at the start of defrost.

After this operation, at step ST45, 3
It is determined whether 0 second has elapsed or not. After 30 seconds have elapsed, the process proceeds to step ST46 where the operating frequency of the first compressor (1a) is set to 86 Hz and the second compressor (1b) is turned on. That is,
Since it is determined in step ST42 that the compressor (1) is in the wet operation state, the rotation speed of the compressor (1) is not suddenly increased, and the compressor (1) is moved into the compressor (1). The introduction of liquid refrigerant is suppressed.

During the defrosting operation, the low-pressure side pressure LP on the compressor suction side is detected by the low-pressure sensor (P2) in step ST47, and the low-pressure side pressure LP is lower than 0.1 kg / cm ^2. When it becomes low, the opening pulse is increased by adding 100 PLS to the opening pulse of the indoor electric expansion valve (13), and the operating frequency of the first compressor (1a) is set to 86 Hz.
The second compressor (1b) is turned off to reduce the number of revolutions of the compressor, thereby suppressing a decrease in the low-pressure side pressure LP. Thereafter, the process proceeds to step ST32, in which the current opening pulse is read as an appropriate value, and if the end determination of the defrost is performed in step ST33, the above-described step ST32 is performed.
Steps ST34 to ST similar to the operations of 13 to 18
By the operation of 39, a return operation to the normal heating operation is performed.

On the other hand, if the result of the determination in step ST42 is NO, in step ST49 (FIG. 9), the compressor (1) during the previous defrost operation measured by the wet time measuring means (15d) becomes wet. It is determined whether the operating time is 0 min, that is, whether or not the vehicle is always dry during the defrosting operation.
At 0, 100PL is applied to the opening pulse of the indoor electric expansion valve (13).
Add S to increase the opening. Meanwhile, this step ST
If NO is determined in step 49, step ST51
To the compressor (1) during the previous defrost operation.
It is determined whether or not the time during which the vehicle has been in the wet operation state is 3 minutes or less. If YES, the current opening pulse of the indoor electric expansion valve (13) is maintained in step ST52. Further, when the determination in step ST51 is NO, that is, when the compressor
If the time during which the (1) was in the wet operation state was longer than 3 min, in step ST53, the indoor electric expansion valve (1) was operated.
Subtract 100 PLS from the opening pulse of 3) to reduce the opening. These operations detect whether or not the environment in which the outdoor unit (A) is installed is such that the compressor (1) is likely to perform wet operation by detecting the wet state during the previous defrost operation. The refrigerant circulation amount adjusting means (15e) performs the indoor electric expansion valve (13) during the defrost operation based on the judgment.
Is corrected so that the refrigerant circulation amount is appropriately adjusted. That is, in an environment condition in which the wet operation of the compressor (1) is unlikely to occur, the opening degree of the indoor electric expansion valve (13) is increased to increase the refrigerant circulation amount to improve the defrost capacity, while In the case of an environmental condition in which the wet operation of (1) is likely to occur, the opening degree of the indoor electric expansion valve (13) is reduced to reduce the amount of circulating refrigerant, and the liquid refrigerant is sucked into the compressor (1). That is being suppressed. Thus, in this example, the indoor electric expansion valve (13) constitutes the refrigerant circulation amount changing means (13 ') of the present invention.

After this operation, in step ST54,
The opening pulse of the indoor electric expansion valve (13) is set to 500 PLS to 200
Restrict to within 0PLS. This is the allowable range of the opening pulse of the indoor electric expansion valve (13) during the defrost operation, and avoids setting the opening pulse outside this range when correcting the opening pulse described above. Operation.

After the opening pulse of the indoor electric expansion valve (13) is set in this way, in steps ST55 and ST56, the same operation as in steps ST44 and ST45 described above is performed. After 30 seconds have passed in step ST56, the operation proceeds to step ST57, where the operation frequency of the first compressor (1a) is 106 Hz and the state of the second compressor (1b) is ON.
The upper limit of the capacity of (1). That is, the above-described step ST
Since it is determined at 42 that the compressor (1) is not in the wet operation state, the introduction of the liquid refrigerant into the compressor (1) does not occur even if the rotation speed of the compressor (1) is set relatively high. Since there is no,
The defrost operation capacity is increased within a range that does not hinder the operation of the compressor (1).

Also, during this defrost operation,
In step ST58, the low pressure side pressure LP on the compressor suction side is detected by the low pressure sensor (P2).
When the LP becomes lower than 0.1 kg / cm ^2, the opening pulse of the indoor electric expansion valve (13) is set to 1000 PLS or more to increase the opening and the operating frequency of the first compressor (1a). Is set to 86 Hz, and the second compressor (1b) is turned on to reduce the rotation speed of the compressor, thereby suppressing a decrease in the low-pressure side pressure LP.
After that, similarly to the above-described operation, the process proceeds to step ST32.
After reading the current opening pulse as an appropriate value,
When the end determination of the defrost is performed in step ST33, the operation of returning to the normal heating operation is performed by the operation of step ST34 to step ST39 described above.

By repeating such normal heating operation and defrost operation, the opening pulse of the indoor electric expansion valve (13) during the defrost operation according to the environment in which the outdoor unit (A) is installed is appropriately adjusted. The liquid refrigerant can be prevented from being introduced into the compressor at the time of the defrost operation and the return of the heating operation, and the performance of the air conditioner can be improved without hindering the operation of the compressor (1). be able to.

(Second Modification) Next, as a control using the oil temperature To used for determining the wet operating state of the compressor (1) as described above, the heating pump down by the compressor capacity adjusting means (15c) is performed. The operation during the residual operation will be described. When the heating operation is started with the liquid refrigerant accumulated in the accumulator (10), this control operation is performed by introducing the liquid refrigerant into the compressor (1) to dilute the lubricating oil or the like. Since the operation of (1) may be hindered, in order to avoid this, the liquid refrigerant in the accumulator (10) is operated for a predetermined time at a low rotation before the compressor stops, and the refrigerant circuit (14) This is an operation of causing the inside to be discharged.

Specifically, in this example, the heating pump down residual operation is performed only when the following three conditions A to C are all satisfied.

Condition A: When the compressor changes from the thermo-on state to the thermo-off state Condition B: HT4a <95 ° C. (H: correction coefficient according to outside air temperature, T4a: discharge pipe temperature of the first compressor) Condition C: below At least one of the conditions a to d is satisfied. A: Within 10 minutes after the compressor is turned on b: Within 20 minutes after the defrost operation or oil return operation c: T7 <−5 ° C. (T7: outside air temperature) d: To ≦ Te + 10 ° C. Also, even when the conditions A to C are satisfied and the heating pump down residual operation is performed, if the thermo-on condition of the compressor (1) is satisfied during the operation, the heating The pump-down residual operation is stopped and normal operation is started. If the accumulated time of the previous normal operation time, the previous residual operation time, and the current normal operation time is 10 minutes or more, the compressor (1) is stopped without performing the heating pump down residual operation.

Next, a specific operation of the heating pump down residual operation will be described. This operation is performed for 10 minutes after the stop signal is input, and the outside air temperature sensor (T
The rotation speed of the compressor (1) is changed according to the outside air temperature detected by h7). In particular,
When the outside air temperature is lower than −10 ° C., the operating frequency of the first compressor (1a) is set to 86 Hz, and the second compressor (1b) is turned off.
When the temperature is -10 ° C or higher and lower than 0 ° C, the operating frequency of the first compressor (1a) is set to 76 Hz and the second compressor (1b) is turned off. The operating frequency of the first compressor (1a) is 60 Hz, and the second compressor (1b) is off. In other words, in a relatively low rotation range where the liquid refrigerant is not introduced into the compressor (1), the lower the outside air temperature, that is, the more the liquid refrigerant easily accumulates in the accumulator (10), the more the first compressor The operating frequency of (1a) is set high to increase the efficiency of recovering liquid refrigerant from the accumulator (10), and the liquid refrigerant in the accumulator (10) is reliably discharged during the remaining 10 minutes of heating pump down operation. I can do it. Further, the opening degree of the indoor electric expansion valve when the (13), until the suction pipe pressure of the compressor (1) rises to 1.5 kg / cm ² to 300PLS, to 1.0 kg / cm ² Until the pressure drops, it is set to 0PLS (fully closed), respectively, to suppress a large fluctuation of the suction pipe pressure.

When the normal operation is started after the heating pump down residual operation, the second compressor (1) is kept for 10 minutes after the start.
b) Turn off.

Further, the heating pump-down residual operation will be described in detail. When at least one of the following five conditions D to H is satisfied, the heating pump-down residual operation is not performed.

Condition D: LP <0.7 kg / cm ² (this detection is performed for 30 seconds
Condition E: HP> 17 kg / cm ² Condition F: HT4a> 110 ° C. Condition G: Start-up retry, abnormality occurrence Condition H: Within 10 minutes after residual operation As described above, in the heating pump down residual operation of this example, As one of the conditions for performing this operation, the oil temperature To in the compressor (1) is detected, thereby determining whether or not the liquid refrigerant is easily introduced into the compressor (1). Because the heating pump down residual operation is performed based on this, when the heating operation is started, the liquid refrigerant in the accumulator (10) is introduced into the compressor (1) to dilute the lubricating oil and compress it. Machine
It is possible to reliably prevent the operation of (1) from being hindered.

In this embodiment, the wet operation state is determined based on the lubricating oil temperature in the compressor (1). However, the present invention is not limited to this, and the discharge pipe temperature of the compressor (1) and the like can be determined. The wet operation state may be determined based on the outside air temperature or the like.

In addition, the present invention can be used in a low outside air heating operation. In other words, the capacity is set to be small in the wet operation state, and the capacity is set to be large otherwise, so that the heating capacity can be improved in the wet operation state.

[0076]

As described above, according to the present invention, the following effects can be obtained.

According to the first and third aspects of the present invention, when the liquid refrigerant is introduced into the compressor during the defrosting operation, the capacity of the compressor can be limited by the compressor capacity limiting means. On the other hand, when the liquid refrigerant is not introduced into the compressor, the capacity limitation of the compressor by the compressor capacity limiting means is released, and a compressor capacity adjusting means for setting the capacity of the compressor high is provided. Particularly, when the liquid refrigerant is not introduced, the compressor is rotated at a high speed so that the defrosting ability is sufficiently exhibited, so that the rotation of the compressor in a fixed pattern regardless of the wet operation state as in the conventional case. The defrosting ability can be improved without hindering the operation of the compressor as compared with the case where the number is set.

Further, according to the first aspect of the present invention, during the defrosting operation, the shorter the wet time during the previous defrosting operation, the greater the refrigerant circulation amount in the refrigerant circulation circuit. A refrigerant circulation amount according to the installation environment of the compressor can be obtained, and the defrosting ability can be further improved while avoiding introduction of the liquid refrigerant to the compressor.

According to the second and third aspects of the present invention, the wet operation state of the compressor is determined based on the lubricating oil temperature detected by the oil temperature detecting means. The capacity of the compressor can be appropriately controlled based on the wetness determination.

According to the fourth aspect of the invention, at the time of heating recovery after the completion of the defrosting operation, the capacity of the compressor is adjusted by the compressor capacity adjusting means in accordance with the wet operating state of the compressor. If not, the limitation on the capacity of the compressor is released, so that the rising performance at the time of heating recovery after the completion of defrosting is improved, and the indoor quick heating performance can be improved.

According to the fifth aspect of the present invention, when the condition for stopping the compressor is satisfied and the liquid refrigerant is introduced into the compressor, the compressor is operated at a low capacity for a predetermined time. In addition, the storage of the liquid refrigerant on the compressor suction side is avoided, and the introduction of the liquid refrigerant into the compressor at the time of startup is suppressed, so that the reliability at the time of startup can be reliably ensured.

[0082] Further, according to the invention of claim 4 and claim 5, since the determined wet operation state of the compressor by the lubricating oil temperature detected by the oil temperature detection means, it can be done accurately wetness determination The capacity of the compressor can be appropriately controlled based on the wetness determination.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of the present invention.

FIG. 2 is a diagram showing a refrigerant piping system of an outdoor unit.

FIG. 3 is a diagram showing a refrigerant piping system of an indoor unit.

FIG. 4 is a flowchart showing a part of the defrosting operation.

FIG. 5 is a flowchart showing a part of a defrost operation operation.

FIG. 6 is a flowchart showing a part of a defrosting operation in a first modified example.

FIG. 7 is a flowchart showing a part of a defrosting operation in a first modified example.

FIG. 8 is a flowchart showing a part of a defrosting operation in a first modified example.

FIG. 9 is a flowchart showing a part of the defrosting operation in the first modified example.

[Explanation of symbols]

 (1) Compressor (5) Four-way switching valve (6) Outdoor heat exchanger (heat source side heat exchanger) (8) Outdoor electric expansion valve (decompression mechanism) (12) Indoor heat exchanger (use side heat exchanger) (13) Indoor electric expansion valve (pressure reducing mechanism) (14) Main refrigerant circuit (refrigerant circulation circuit) (15a) Compressor capacity limiting means (15b) Wetness judging means (15c) Compressor capacity adjusting means (15d) Wetting time Measuring means (15e) Refrigerant circulation amount adjusting means (Tho) Oil temperature sensor (oil temperature detecting means)

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-203762 (JP, A) JP-A-7-139857 (JP, A) JP-A-60-104680 (JP, U) (58) Field (Int.Cl. ⁷ , DB name) F25B 47/02 570

Claims (5)

(57) [Claims] 1. A variable capacity compressor (1), a heat source side heat exchanger
(6) The refrigerant circulation circuit (14), in which the pressure reduction mechanisms (8), (13) and the use side heat exchanger (12) are connected in order so that the refrigerant can circulate, and the cycle of the refrigerant circulation circuit (14) Four-way switching valve (5) switchable between cooling and defrosting operation cycle and heating operation cycle
A compressor capacity limiting means (15a) for limiting the capacity of the compressor (1) to a predetermined low capacity value during the defrosting operation, and a refrigerant circulation circuit ( The output of the wetness judging means (15b), which detects that the circulation state of the refrigerant in 14) is a state in which the liquid refrigerant is introduced into the compressor (1), and the output of the wetness judging means (15b) are received. When the liquid refrigerant is introduced into the compressor (1), the capacity of the compressor (1) is allowed to be limited by the compressor capacity limiting means (15a), while the liquid refrigerant is introduced into the compressor (1). When the compressor (1) is not introduced, the compressor (1)
To release the capacity limit, the compressor and the compressor capacity adjustment means the capacity of (1) is set higher than the predetermined value (15c), provided in the refrigerant circuit (14), the refrigerant circulation amount A variable refrigerant circulation amount changing means (13 '); a wet time measuring means (15d) for measuring a wet time during which the liquid refrigerant remains in the compressor (1) during the defrosting operation; and a wet time measuring means. (15d), during the defrosting operation and during the previous defrosting operation, the wet time measuring means (1
The shorter the wet time measured by 5d), the shorter the refrigerant circulation circuit
(14) a refrigerant circulating amount adjusting means (15e) for adjusting the refrigerant circulating amount changing means (13 ') so as to increase the refrigerant circulating amount in (14). apparatus. The compressor (1) has an oil temperature detecting means (Th) for detecting the temperature of lubricating oil stored inside the compressor (1).
o) is provided, and the wetness determination means (15b) compares the oil temperature detected by the oil temperature detection means (Tho) with the refrigerant temperature on the compressor suction side, thereby making the compressor (1) The operation control device for an air conditioner according to claim 1, wherein it is determined that the liquid refrigerant is introduced into the inside. 3. A variable capacity compressor (1), a heat source side heat exchanger
(6) The refrigerant circulation circuit (14), in which the pressure reduction mechanisms (8), (13) and the use side heat exchanger (12) are connected in order so that the refrigerant can circulate, and the cycle of the refrigerant circulation circuit (14) Four-way switching valve (5) switchable between cooling and defrosting operation cycle and heating operation cycle
A compressor capacity limiting means (15a) for limiting the capacity of the compressor (1) to a predetermined low capacity value during the defrosting operation, and a refrigerant circulation circuit ( The output of the wetness judging means (15b), which detects that the circulation state of the refrigerant in (14) is a state in which the liquid refrigerant is introduced into the compressor (1), and the output of the wetness judging means (15b) When the liquid refrigerant is introduced into the compressor (1), the capacity of the compressor (1) is allowed to be limited by the compressor capacity limiting means (15a), while the liquid refrigerant is introduced into the compressor (1). When the compressor (1) is not introduced, the compressor (1)
To release the capacity limit, the compressor capacity adjusting means for the displacement of the compressor (1) is set higher than the predetermined value and (15c) are provided, the said compressor (1), the compressor (1) Oil temperature detecting means (Tho) for detecting the temperature of the lubricating oil stored inside is provided, and the wetness judging means (15b) detects the oil detected by the oil temperature detecting means (Tho). The air conditioner is characterized in that by comparing the temperature and the refrigerant temperature on the compressor suction side, it is determined that the liquid refrigerant is introduced into the compressor (1). Operation control device. 4. A variable capacity compressor (1), a heat source side heat exchanger
(6) The refrigerant circulation circuit (14), in which the pressure reduction mechanisms (8), (13) and the use side heat exchanger (12) are connected in order so that the refrigerant can circulate, and the cycle of the refrigerant circulation circuit (14) Four-way switching valve (5) switchable between cooling and defrosting operation cycle and heating operation cycle
In the air conditioner provided with the above, when returning to the heating operation after the end of the defrosting operation, the compressor capacity limiting means (15a) for limiting the capacity of the compressor (1) to a predetermined low capacity value
When returning to the heating operation, the refrigerant circulation state in the refrigerant circulation circuit (14), wetness determination means (15b) that detects that the liquid refrigerant is introduced into the compressor (1) inside When the output of the wetness judging means (15a) is received and the liquid refrigerant is introduced into the compressor (1), the capacity limitation of the compressor (1) by the compressor capacity limiting means (15a) is permitted. do it,
While the compressor (1) is operated at the predetermined low capacity for the predetermined time, when the liquid refrigerant is not introduced into the compressor (1), the compressor (1) is controlled by the compressor capacity regulating means (15a).
Provided a compressor capacity adjusting means for releasing the quota (15c) is, in the compressor (1), the compressor (1) oil temperature detection for detecting the temperature of lubricating oil stored therein Means (Tho) is provided, and the wetness determining means (15b) compares the oil temperature detected by the oil temperature detecting means (Tho) with the refrigerant temperature on the compressor suction side to determine whether the compressor ( 1) An operation control device for an air conditioner, which is configured to determine that a liquid refrigerant is introduced therein. 5. A compressor (1) having a variable capacity, a heat source side heat exchanger (6), a pressure reducing mechanism (8), and a use side heat exchanger (12) are sequentially connected so as to be able to circulate a refrigerant. In the air conditioner provided with the refrigerant circulation circuit (14), the refrigerant circulation state in the refrigerant circulation circuit (14) is such that the liquid refrigerant is introduced into the compressor (1). Upon receiving the outputs of the wetness determining means (15b) to be detected and the wetness determining means (15b), when the compressor stop condition is satisfied and the liquid refrigerant is introduced into the compressor (1), the compressor ( While the compressor (1) is operated for a predetermined time while restricting the capacity of (1) to a low capacity at which introduction of liquid refrigerant is avoided, when the liquid refrigerant is not introduced into the compressor (1), the compressor (1) Compressor capacity adjustment means that can be stopped
(15c) and is provided, in the compressor (1), and the compressor (1) oil temperature detecting means for detecting a temperature of lubricating oil stored inside (Tho) is provided, wetness The judging means (15b) compares the oil temperature detected by the oil temperature detecting means (Tho) with the refrigerant temperature on the compressor suction side to determine whether the liquid refrigerant is introduced into the compressor (1). An operation control device for an air conditioner, wherein the operation control device is configured to determine that: