JPH0217370A - Operation control device for air conditioning device - Google Patents

Abstract

PURPOSE:To effectively prevent the oil rise of a compressor by a method wherein before a defrosting operation is completed, a motor-operated expansion valve is previously brought into a fully opened state, and after it is held at a fully opened state for a given time starting from the completion, the opening of the valve is gradually closed to a value during ordinary operation. CONSTITUTION:When it is noticed in advance by a completion advance-notice means 33 that a defrosting operation is completed shortly, a completion operation control means 35 stops control of the opening of a motor-operated expansion valve 5 effected by means of an expansion valve control means 32, and an opening is previously set to its full opening before the defrosting operation is completed. When it is detected by a completion detecting means 34 that defrost operation is completed, an electromagnetic valve 12 is closed by a valve control means 31. Simultaneously with completion of defrost operation, the motor-operated expansion valve 5 is held at a full opening state for a given time by means of the completion control means 35, and is closed to a given opening responding to a current air conditioning load. A rapid increase in refrigerant resistance is transiently prevented from occurring to a refrigerant circuit 9, and a level in an accumulator 6 is prevented from rapid lowering. This constitution enables effective prevention of the oil rise of a compressor.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an operation control device for an air conditioner that performs a positive cycle defrost operation, and in particular, a method for preventing oil from rising in a compressor at the end of a defrost operation. Regarding.

(Prior Art) Conventionally, as an operation control device for an air conditioner, a compressor, an outdoor heat exchanger, a pressure reduction mechanism, and an indoor heat exchanger are sequentially connected, as disclosed in Japanese Patent Application Laid-open No. 57-169567, for example. In an air conditioner equipped with a refrigerant circuit, a hot gas bypass path is provided that connects the discharge pipe of the compressor and the liquid pipe side of the outdoor heat exchanger so that the refrigerant can be bypassed. A so-called positive cycle defrosts the outdoor heat exchanger by interposing a valve and opening the electromagnetic on-off valve to bypass a portion of the discharged gas to the outdoor heat exchanger when frost forms during heating operation. A defrost operation is known as a well-known technique.

(Problems to be Solved by the Invention) Incidentally, in the case of the above-mentioned normal cycle defrost operation, the following procedure is generally performed. That is, as shown in Figure 5 (a), with the start of defrost operation,
The operating capacity of the compressor (operating frequency if equipped with an inverter) is increased (time t1) and set to the maximum capacity at times t and 2. After that, the compressor is operated at the maximum capacity for a predetermined period of time, and the outdoor heat exchanger is defrosted. When this is completed (time t4), the operating capacity is returned to the normal capacity (time ts) and normal heating operation is performed. At this time, the pressure reducing mechanism is set to a predetermined opening degree based on the air conditioning load during normal operation, and is set to a constant low opening degree during defrost operation. For example, as shown in FIG. 5(b), after performing heating operation for a predetermined time (until time T3) with the operating capacity of the compressor at its maximum and the pressure reducing mechanism at an opening degree corresponding to the operating capacity, the above-mentioned hot The defrost operation may be started by opening the electromagnetic on-off valve of the gas bypass path (see FIG. 5(c)).

When the defrost operation ends, the electromagnetic on-off valve is closed, the operating capacity of the compressor and the pressure reducing mechanism are returned to the normal heating operation state, and the heating operation is resumed.

However, when performing the above-described normal cycle defrost operation, there has been a problem in which oil rises momentarily in the compressor when returning from the defrost operation to normal heating operation.

Considering the cause, the high and low pressures of the compressor vary depending on the operating capacity of the compressor and the opening/closing or opening degree changes of each valve.
Changes as shown in Figures (d) and (e) occur, but in particular,
At the end of the defrost operation, the closing operation of the electromagnetic on-off valve changes from the defrost operation, which had almost no pressure reduction, to the heating operation, which is a predetermined pressure reduction state.
A sudden increase in resistance of the refrigerant occurs in the refrigerant circuit.

As a result, the low pressure transiently decreases significantly (see time T5 in Figure 5 (e)), and - the refrigerant returns to the instantaneous compressor, causing the liquid level in the accumulator to drop. (see time T5), it is presumed that the oil level in the compressor decreases, that is, so-called oil rise occurs.

The present invention has been made in view of the above circumstances, and its purpose is to eliminate the sudden pressure change in the refrigerant circuit when returning from defrost operation to heating operation, thereby reducing oil rise in the compressor during transient conditions. The goal is to prevent

(Means for Solving the Problem) In order to achieve the above object, the solving means of the invention of claim (1) provides a compressor (
1), a refrigerant circuit (9) formed by connecting an outdoor heat exchanger (3), an electric expansion valve (5), an indoor heat exchanger (7), and an accumulator (6) so that refrigerant can be circulated; and the compressor. (1
) and a bypass path (11) connecting the discharge pipe (8a) and liquid pipe (8b) of the refrigerant so that the refrigerant can be bypassed;
11), an on-off valve control means (31) that controls the electromagnetic on-off valve (12) to open only during defrost operation, and an electric expansion valve (5).
The present invention is based on an air conditioner equipped with an expansion valve control means (32) that controls the opening degree of the expansion valve to a predetermined opening degree based on the air conditioning load during normal operation and to a constant low opening degree during defrost operation.

As an operation control device for the air conditioner, there is provided an end notice means (33) for notifying the end of the defrost operation, and an end detecting means (34) for detecting the end of the defrost operation.
Upon receiving the output of the termination notification means (33), the control by the expansion valve control means (32) is forcibly stopped, the opening degree of the electric expansion valve (5) is set to fully open in advance, and the termination is detected. In response to the output of the means (34), the electric expansion valve (5) is kept fully open for a predetermined period of time from the end of the defrost operation, and then gradually closed to a predetermined opening according to the air conditioning load at that time. Control end operation control means (35)
The configuration is such that the following is provided.

Furthermore, as shown in FIG.
1), a refrigerant circuit (9) formed by connecting an outdoor heat exchanger (3), an electric expansion valve (5), an indoor heat exchanger (7), and an accumulator (6) so that refrigerant can be circulated; and the compressor. (1
) and a bypass path (11) that connects the discharge pipe (8a) and liquid pipe (8b) of the refrigerant so that the refrigerant can be bypassed;
11), an on-off valve control means (31) that controls the electromagnetic on-off valve (12) to open only during defrost operation, and an electric expansion valve (5).
During normal operation, the opening is set to a predetermined opening based on the air conditioning load.
An air conditioner equipped with an expansion valve control means (32) that controls the opening to a constant low degree during defrost operation, and a capacity control means (36) that controls the operating capacity of the compressor (1) to a predetermined capacity based on the air conditioning load. Targeting equipment.

As an operation control device for the air conditioner, there is provided an end notice means (33) for notifying the end of the defrost operation, and an end detecting means (34) for detecting the end of the defrost operation.
Upon receiving the output of the termination notice means (33), the control by the expansion valve control means (32) and the capacity control means (36) is forcibly stopped, and the electric expansion valve (5) is fully opened in advance. In addition, the operating capacity of the compressor (1) is set to the minimum, and in response to the output of the end detection means (34), the electric expansion valve (5) is fully opened and compressed for a predetermined period of time from the end of the defrost operation. After maintaining the operating capacity of the compressor (1) to the minimum, the electric expansion valve (5) is gradually closed to a predetermined opening according to the air conditioning load at that time, and the operating capacity of the compressor (1) is reduced to the predetermined capacity. The configuration includes a termination operation control means (35) for controlling the operation so as to return to the original condition.

(Function) With the above configuration, in the invention of claim (1), when the end notice means (33) warns that the reso-frost operation will soon end, when the defrost operation ends, the end operation control means (35) ), the opening degree control of the electric expansion valve (5) by the expansion valve control means (32) is forcibly stopped, so that the opening degree of the electric expansion valve (5) is fully opened before the end of the defrost operation. is set to When the end detection means (35) detects the end of the defrost operation, the on-off valve control means (31) controls the electromagnetic on-off valve (1).
2) is closed, and the normal cycle defrost operation by bypassing the discharged gas is completed. At the same time, after the electric expansion valve (5) is kept fully open for a predetermined period of time by the termination operation control means (35), it is gradually closed to a predetermined opening according to the air conditioning load at that time.

In that case, in the refrigerant circuit (9), the defrost operation without throttling of the refrigerant shifts to the heating operation in which the refrigerant is subjected to a predetermined throttling, but since the electric expansion valve (5) is kept fully open, Since the refrigerant resistance in the circuit is kept small, a sudden sudden increase in refrigerant resistance does not occur. Moreover, since the opening degree of the electric expansion valve (5) is then gradually closed and the normal operating state is entered, there is no sudden change in the resistance of the refrigerant during this period.

Therefore, a drop in low pressure is suppressed, and the accumulator (6)
As a result, the oil level in the compressor (1) is effectively prevented from rising.

Furthermore, in the invention of claim (2), the termination notice means (33)
In response to the output, the termination operation control means (35) controls the opening of the electric expansion valve (5) by the expansion valve control means (32) and the operating capacity of the compressor (1) by the capacity control means (36). is forcibly stopped, and before the end of the defrost operation, the opening degree of the electric expansion valve (5) is fully opened and the operating capacity of the compressor (1) is set to the minimum, and the end detection means (34) is set in advance. After receiving the output, it is held as it is for a predetermined period of time. Thereafter, the opening degree of the electric expansion valve (5) is gradually closed to a predetermined opening degree according to the air conditioning load at that time, and the operating capacity of the compressor (1) returns to the predetermined capacity. Therefore, in addition to the effect of the above claim (1), the compressor (1)
The effect of suppressing the oil flow rate can be obtained in an additive manner by reducing the operating capacity of the engine.

(Example) Examples of the present invention will be described below with reference to FIGS. 2 to 4.

FIG. 2 shows the overall configuration of an air conditioner according to an embodiment of the invention of claims (1) and (2), and shows one outdoor unit (
It has a separate configuration in which one indoor unit (B) is connected to A).

In the above outdoor unit, (1) is a compressor, (2) is a four-way switching valve that switches as shown in the solid line in the figure during cooling operation and as shown in the broken line in the figure during heating operation, (3) is a condenser during cooling operation, An outdoor heat exchanger (3a) functions as an evaporator during heating operation, (3a) is two outdoor fans attached to the outdoor heat exchanger (3), and (4) decompresses the refrigerant. A capillary tube, (5) is an electric expansion valve connected in parallel to the capillary tube (4) and whose opening degree is variably adjusted, and (6) is an accumulator for separating liquid refrigerant in the suction gas. , by the capillary tube (4) and the electric expansion valve (5),
The throttle ratio of the refrigerant in the refrigerant circuit (9) is determined.

In the indoor unit CB), (7) is an indoor heat exchanger that serves as an evaporator during cooling operation and a condenser during heating operation, and (7a) to (7d) are attached to the indoor heat exchanger (7). There are four indoor fans.

The above-mentioned devices (1) to (7) are connected through refrigerant piping (8) so that refrigerant can be circulated, and the outdoor heat exchanger (3) transfers the heat imparted by heat exchange with outdoor air. A refrigerant circuit (9) having a heat pump function for discharging indoors is configured.

Here, the compressor (1) is connected to an attached inverter (1).
The operating capacity of the compressor (1) is adjusted according to changes in the operating frequency. In addition, a bypass path (11) is provided between the discharge pipe (8a) of the compressor (1) and the liquid pipe side header (3C) arranged on the liquid pipe (8b) side of the outdoor heat exchanger (3). The bypass passage (11) is connected to allow the flow of refrigerant, and an electromagnetic on-off valve (12) for opening and closing the passage is provided.

Furthermore, the air conditioner is equipped with nine switches, and (SS) is arranged on the suction pipe (8C) side of the compressor (1), and includes a suction pipe sensor for detecting the suction pipe temperature Ts; (HPSI) is the first pressure switch for high pressure cutoff arranged in the discharge pipe (8a), (HPS2) is the bypass path (
11), and when the high pressure HP reaches a predetermined value or higher, the solenoid valve (12) is opened and the hot gas is transferred to the liquid pipe (8b).
) side for bypassing the second pressure switch,
Each sensor 1 switch type (SS), (HPSI
).

The output of (HPS2) is connected to a control unit (13) that controls the operation of the entire air conditioner so that signals can be input.

In Fig. 2, (14) is a compressor accumulator attached to the compressor (1), and (15) is a refrigerant circuit (9).
), (16), (
16) is a manual shutoff valve installed in the connecting pipe between the outdoor unit (A) and the indoor unit (B), and (17) is from the liquid pipe side header (3C) of the outdoor heat exchanger (3). Liquid pipe (
Liquid return pipe (8d) for bypassing refrigerant to 8b)
This is a check valve installed inside.

During heating operation of the air conditioner, the four-way switching valve (2) is switched to the side shown by the broken line in the figure, and operation is performed with the electromagnetic on-off valve (12) closed, and the discharged gas is transferred to the indoor unit (B). The air is circulated through the indoor heat exchanger (7) and condensed by heat exchange with the indoor air, at the same time giving warm heat to the indoor air, and subjected to a throttling action by the electric expansion valve (5) and capillary tube (4). The air is evaporated in the outdoor heat exchanger (3), heated by the outdoor air in the outdoor heat exchanger (3), and then returned to the compressor (1) via the accumulator (6) (as shown by the solid arrow in the figure). reference). In addition, during cooling operation, the four-way switching valve (2) switches as shown by the solid line in the figure, and the operation is performed with the electromagnetic on-off valve (12) closed, causing the indoor Cooling is performed.

If the outdoor heat exchanger (3) is frosted during the above-mentioned heating operation, high-temperature discharge gas is discharged from the compressor (1) while performing the heating operation in the refrigerant circuit (9), as shown by the broken line arrow in the figure. A part of the liquid is bypassed to the liquid pipe (8b) side, and a defrost operation is performed in which the heat is circulated so as to provide heat to the outdoor heat exchanger (3) by a condensing action. And at that time,
Defrost operation control is performed by the control unit (13). Fig. 3 is a flowchart showing the control flow during defrost operation, and Fig. 4 shows the operating frequency of the inverter (10) at that time, and the electric expansion valve (5).
opening degree, opening/closing status of the electromagnetic on-off valve (12), high pressure, low pressure,
FIG. 4 is a characteristic diagram showing changes in the liquid level of the accumulator (6) and the oil level of the compressor (1), respectively. Defrost operation control will be described below with reference to FIGS. 3 and 4. FIG.

First, when a defrost operation command is output from a signal from a defrost sensor, etc., in step S1, the inverter (10) is activated to warm up the compressor (1) and increase the high pressure to increase the efficiency of the defrost operation. The operating frequency is increased from the predetermined capacity according to the air conditioning load up to that point to the maximum opening (time T+ in Figure 4 (a)), and the indoor fan (
By performing the heating operation for a predetermined period of time with 7a) to 7d stopped, the compressor (1) is warmed and the high pressure is increased. At this time, the opening degree of the electric expansion valve (5) is controlled according to the operating frequency of the inverter (10), that is, according to the air conditioning load (time T1 to time T2 in FIG. 4(b)). Then, in step S2, when the high pressure (IP) rises sufficiently to reach a predetermined set value (IP+) (see Fig. 4 (D)).
At time T2), the second pressure control valve (HPSI) is activated, and in step S3, the electromagnetic on-off valve (12) is opened (the fourth
Time T2 in Figure (C)) Sufficiently warmed hot gas is directly introduced into the liquid pipe side header (3c) of the outdoor heat exchanger (3), and at the same time, the electric expansion valve (5) is fully closed in step S4. (time T2 in Figure 4 (b)).

In other words, a part of the hot gas is directly transferred to the outdoor heat exchanger (3).
A forward cycle defrost operation is performed in which the liquid is introduced into the liquid pipe (8b) side.

Under the above conditions, perform defrost operation to connect the outdoor heat exchanger (
3) is defrosted and the suction pipe temperature Ts detected by the suction pipe sensor (SS) recovers to a predetermined value TsL, a warning signal is output to stop the defrost operation, and the inverter ( 10) to the minimum (time T3 in Fig. 4 (a)), and at the same time open the electric expansion valve (5) until it is fully open (Fig. 4 (a)).
b) time T3). Next, in step S7, wait until the suction pipe temperature Ts reaches the defrost operation end temperature Ts2 (for example, about 6°C), and then proceed to step S8 to close the electromagnetic on-off valve (12) (see Fig. 4 (c)). time T4), and at the same time a timer (not shown) in the control unit (13)
Start counting. Then, in step S9, wait for a predetermined time (for example, about 1 minute) to elapse, and then proceed to step SIO, where the operating frequency of the inverter (10) is increased from the minimum value to a predetermined value according to the air conditioning load at that time. At the same time (time Ts in Figure 4 (a)),
By changing the pulse position of the electric expansion valve (5) little by little, its opening degree is gradually closed to a predetermined opening degree depending on the operating frequency of the inverter (10) (time Ts in FIG. 4 (b)).

Then, in step Sl+, the normal heating operation is resumed and the control is ended.

In the above flow, in the invention of claim (1), steps S3 and S8 constitute an on-off valve control means (31) that controls the electromagnetic on-off valve (12) to open only during the defrost operation, and steps S4 and In S11, the expansion valve control means (32) controls the opening degree of the electric expansion valve (5) to a predetermined opening degree based on the indoor load during normal operation, and to a constant low opening degree according to the air conditioning load during defrost operation.
) is configured. Further, step S5 constitutes a termination notice means (33) for notifying the end of the defrost operation, and step S7 constitutes an end detection means (34) for detecting the end of the defrost operation. Furthermore, in step S6 and SIO, upon receiving the output of the termination notice means (33), the control by the expansion valve control means (32) is forcibly stopped and the opening degree of the electric expansion valve (5) is set in advance to be fully open. At the same time, the end detection means (34
), the opening of the electric expansion valve (5) is kept fully open for a predetermined period of time from the end of the defrost operation, and then gradually closed to a predetermined opening according to the air conditioning load at that time. An operation control means (35) is configured.

On the other hand, in the invention according to claim (2), in step S11, the expansion valve control means (32) and the capacity control means (36) for controlling the operating capacity of the compressor (1) to a predetermined capacity based on the air conditioning load. In step S6 and SIO, the electric expansion valve ( 5) is set to the maximum and the operating capacity of the compressor (1) is set to the minimum, and upon receiving the output of the end detection means (34), the electric expansion valve (5) is fully opened for a predetermined period of time. After the operating capacity of the compressor (1) is maintained at the minimum, the opening degree of the electric expansion valve (5) is gradually closed to a predetermined opening degree according to the air conditioning load at that time, and the operating capacity of the compressor (1) is increased. A termination operation control means (35) is configured to control the operation so as to restore the capacity to a predetermined capacity. Note that the configuration of other means is the same as the invention of claim (1) above.

Therefore, in the above embodiment, in the invention of claim (1), at the end of the defrost operation, the end notice means (33)
When the defrost operation is predicted to end soon, the end operation control means (35) forcibly stops the opening control of the electric expansion valve (5) by the expansion valve control means (32), and the defrost operation is stopped. The opening degree of the electric expansion valve (5) is set in advance so that it becomes fully open by the end of the operation. When the end detection means (35) detects the end of the defrost operation, the on-off valve control means (31) closes the electromagnetic on-off valve (12), and the normal cycle defrost operation by hot gas bypass ends. . At the same time, the opening degree of the electric expansion valve (5) is kept fully open for a predetermined time by the end operation control means (35) for a predetermined time.

In that case, the refrigerant circuit (9) shifts from the defrost operation without throttling of the refrigerant to the heating operation with a predetermined throttling of the refrigerant, but since the electric expansion valve (5) is held fully open, In addition, the refrigerant resistance in the circuit is maintained small, and the resistance does not increase suddenly unlike the conventional circuit (see time T4 in FIG. 4(e)). In addition, the opening degree of the electric expansion valve (5) is then gradually reduced to the opening degree corresponding to the air conditioning load of the heating operation, that is, the operating capacity of the compressor (1). This does not cause an increase in refrigerant resistance.

Therefore, the decrease in the low pressure LP is suppressed (see time T4 in FIG. 4(e)), and the liquid level in the accumulator (6) does not drop suddenly (see time T4 in FIG. 4(f)). As a result, as shown in FIG. 4 (g), oil leakage in the compressor (1) is effectively prevented.

Further, in the invention of claim (2), upon receiving the output of the termination notice means (33), the termination operation control means (35) forcibly controls the expansion valve control means (32) and the capacity control means (36). The electric expansion valve (5) is fully opened and the inverter (
10), the operating frequency of the compressor (1), that is, the operating capacity of the compressor (1), is set to the minimum and held as it is for a predetermined time after receiving the output of the end detection means (34). After a predetermined period of time has elapsed, the electric expansion valve (5) is gradually closed to a predetermined opening degree depending on the air conditioning load at that time, and the compressor (1
)'s operating capacity returns to the predetermined capacity. Therefore, in addition to the effect of claim (1) above, it is possible to obtain an additional effect of suppressing the oil rising rate by reducing the operating capacity of the compressor (1) at the end of the defrosting operation.

In addition, in the above embodiment, the end of the defrost operation is announced,
Although the suction pipe sensor is arranged for detection, an outside air temperature sensor or the like may be used instead, and the end of the defrost operation may be forewarned or detected based on the difference in the detected values.

(Effects of the Invention) As explained above, according to the invention of claim (1), in the operation control device for an air conditioner that performs a positive cycle defrost operation, the electric expansion valve is activated in advance before the end of the defrost operation. The system is fully open, held fully open for a predetermined period of time, and then gradually closed to normal operation. This suppresses the increase in oil content and effectively prevents oil from rising in the compressor.

Further, according to the invention of claim (2), a variable capacity compressor is arranged, and the electric expansion valve is fully opened and the compressor is set to the minimum capacity before the end of the defrost operation, and the compressor is left as it is for a predetermined time after the end of the defrost operation. After holding the electric expansion valve, the electric expansion valve is gradually closed to the opening degree for normal operation, and the compressor is returned to the capacity for normal operation, so that in addition to the effect of the invention of claim (1), the oil rise rate is further reduced. The suppressive effect can be obtained in an additive manner.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of the present invention. 2 to 4 each show an embodiment of the invention of claims (1) and (2), with FIG. 2 being an overall configuration diagram thereof, FIG. Figure (a)
-(g) are inverter frequency, electric expansion valve opening degree,
Solenoid valve open/close status, high pressure, low pressure, accumulator liquid level,
FIG. 3 is a characteristic diagram showing changes in the oil level of the compressor. FIG. 5 is a diagram corresponding to FIG. 4 in a conventional control device. (1)...Compressor, (3)...Outdoor heat exchanger, (5
)...Electric expansion valve, (6)...Accumulator, (
7)...Indoor heat exchanger, (8a)...Discharge pipe, (8
b)...Liquid pipe, (9)...Refrigerant circuit, (11)...
・Bypass path, (12)...Solenoid on-off valve, (31)・
...Opening/closing valve control means, (32)...Expansion valve control means,
(33)...Completion notice means, (34)...Completion detection means, (35)...Completion operation control means, (36)...
・Capacity control means. Patent Applicant Daikin Industries, Ltd. Agent Patent Attorney Former 1) Hiroshi (2 people) ---,-,,5--Figure I3 Figure O Figure-----------T----1 Figure 1

Claims (2)

[Claims] (1) Compressor (1), outdoor heat exchanger (3), electric expansion valve (5), indoor heat exchanger (7) and accumulator (6)
) connected to enable circulation of refrigerant;
a bypass path (11) connecting the discharge pipe (8a) and the liquid pipe (8b) of the compressor (1) so that refrigerant can be bypassed;
An electromagnetic on-off valve (12) interposed in the bypass path (11)
and an on-off valve control means (31) that controls the electromagnetic on-off valve (12) to open only during defrost operation, and an opening of the electric expansion valve (5) to a predetermined opening based on the air conditioning load during normal operation. In the air conditioner, the air conditioner is equipped with an expansion valve control means (32) for controlling the opening to a constant low degree during the defrost operation, and a termination notice means (33) for notifying the end of the defrost operation, and detecting the end of the defrost operation. In response to the output of the termination detection means (34) and the termination notification means (33), the control by the expansion valve control means (32) is forcibly stopped and the opening degree of the electric expansion valve (5) is adjusted in advance. At the same time, in response to the output of the end detection means (34), the electric expansion valve (5) is kept fully open for a predetermined period of time from the end of the defrost operation, and then gradually adjusted according to the air conditioning load at that time. An operation control device for an air conditioner, comprising: an end operation control means (35) for controlling the opening to close to a predetermined degree. (2) Compressor with variable operating capacity (1), outdoor heat exchanger (3)
), a refrigerant circuit (9) formed by connecting an electric expansion valve (5), an indoor heat exchanger (7), and an accumulator (6) so that refrigerant can circulate, and a discharge pipe (8a) of the compressor (1). a bypass passage (11) connecting the liquid pipe (8b) and the liquid pipe (8b) so that the refrigerant can be bypassed; 12) is opened.
1), an expansion valve control means (32) that controls the opening of the electric expansion valve (5) to a predetermined opening based on the air conditioning load during normal operation and to a constant low opening during defrost operation, and a compressor ( In the air conditioner, the air conditioner is equipped with a capacity control means (36) for controlling the operating capacity to a predetermined capacity based on the air conditioning load.
33), a completion detection means (34) for detecting the end of the defrost operation, and an output from the completion notice means (33), and the expansion valve control means (32) and the capacity control means (3).
6) is forcibly stopped and the electric expansion valve (5) is fully opened and the operating capacity of the compressor (1) is set to the minimum, and the output of the end detection means (34) is In response to this, the electric expansion valve (5) is kept fully open for a predetermined period of time from the end of the defrost operation, and the operating capacity of the compressor (1) is maintained at the minimum. (5) to gradually close the opening to a predetermined opening and control the operating capacity of the compressor (1) to return to the predetermined capacity. Equipment operation control device.