JP2555779B2 - 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 measures for preventing an excessive rise in discharge refrigerant temperature and high-pressure side pressure after completion of defrost operation.

[0002]

2. Description of the Related Art Conventionally, for example, Japanese Patent Laid-Open No. 59-1706.
As disclosed in Japanese Unexamined Patent Publication No. 62-62, as an operation control device for an air conditioner, when frost is generated during a heating operation, the cycle is switched to perform a so-called reverse cycle defrost operation, while the cycle is changed after the defrost operation is completed. By returning to the normal cycle and performing heating operation, the fan of the outdoor heat exchanger is stopped for a predetermined time and then operated to discharge the amount of heat remaining in the outdoor heat exchanger to the outside at the end of the defrost operation. Without returning to the refrigerant system,
A known technique is to improve the refrigerating capacity.

[0003]

However, when the outdoor fan is stopped after the defrosting is finished as in the above-mentioned conventional one, the operating efficiency is improved, but there are the following problems. That is, the relatively high temperature refrigerant is stored in the outdoor heat exchanger that has been the condenser during the defrost operation by the reverse cycle defrost, and this high temperature refrigerant is sucked into the compressor after the cycle switching. . However, depending on the operating conditions, the opening degree of the electric expansion valve is reduced immediately before the end of the defrost operation to perform the pump down operation,
Controls such as preventing liquid back to the compressor may be performed.In such cases, the high-pressure side pressure and the discharge pipe temperature may temporarily rise excessively, causing an operation stop, which impairs reliability. There was fear.

The present invention has been made in view of the above points, and an object thereof is to improve reliability by providing a means for suppressing an excessive rise in high pressure after the completion of defrosting.

[0005]

[Means for Solving the Problems] To achieve the above object, the means taken by the present invention is a compressor, an outdoor fan (3
Outdoor heat exchanger (3) with a) attached, electric expansion valve (5)
And an indoor air heat exchanger (6) are sequentially connected, and an air conditioner provided with a refrigerant circuit (9) configured to be cycle-switchable is assumed.

[0006] Then, Chakushimoji of the outdoor heat exchanger during heating operation (3), the defrosting operation control means for controlling the refrigerant circuit (9) to perform the reverse cycle defrosting operation (51), said defrost Operation control means (51)
The reverse cycle defrosting operation by said electric expansion valve (5) opening a large and the electric as squeeze immediately before the end of the
And opening control means for controlling the expansion valve (5), the outdoor fan (3 until after completion of the defrosting operation by the defrosting operation control means (51), a predetermined stop time has elapsed
After stopping a), the outdoor fan should be operated so as to operate.
A fan control means (52 ) for controlling (3a) is provided.
Has been.

Further, the defrost operation control means (5
After the defrost operation according to 1) is completed, the control of the fan control means (52) is forcibly stopped and at least the fan control means (52) is stopped.
Constant force shorter than the stop time of the fan control means (52)
Operate the outdoor fan (3a) until the operating time elapses
A forced fan operating means (53) and a discharge temperature detecting means (Th2) for detecting the discharge refrigerant temperature are provided.
It

In addition, when the output of the discharge temperature detecting means (Th2) is received, the forced operation of the fan forced operation means (53) is performed.
After the interval has passed, until the temperature of the discharged refrigerant exceeds the specified temperature
Outdoor fan (3a) by means of forced fan operation (53)
And the fan control means
Before the stop time of (52) elapses, the discharge refrigerant temperature is
When the temperature exceeds a certain temperature, the above-mentioned fan forced operation means (53) is controlled.
Control is stopped, and control is transferred to the fan control means (52).
A resetting means (54) is provided.

[0009]

With the above construction, in the present invention, when the outdoor heat exchanger (3) is frosted during the heating operation of the air conditioner, the four-way switching valve (2) is controlled by the defrost operation control means (51).
Is switched to the cooling cycle side, so-called reverse cycle defrost operation is performed, and when defrosting is completed, the cycle is switched to the heating cycle again and heating operation is performed. then,
The opening control means, during defrost operation, but usually is controlled to an opening degree of the electric expansion valve (5) to substantially fully open,
Immediately before the end of the defrost operation, the opening of the electric expansion valve (5) is throttled to prevent liquid back to the compressor (1) at the time of heating return, so that the refrigerant circuit (9) is pumped down and the receiver ( The refrigerant is stored in 6), and the circulation amount of the refrigerant is reduced.

[0010] Then, the fan control means (52), when it is controlled to stop the operation of the outdoor fan (3a) until the elapse of the defrost operation end after a predetermined stop time, the outdoor heat exchanger (3) Since the high temperature refrigerant that has accumulated in the compressor (1) is sucked into the compressor (1) and the refrigerant circulation amount is small, the discharged refrigerant temperature tends to rise rapidly .

At this time, since the outdoor fan (3a) is operated by the forced fan operation means (53) for a certain forced operation time or longer , during this period, the evaporation amount of the refrigerant increases and the outdoor heat exchange increases. While the liquid refrigerant in the device (3) is cooled, the refrigerant circulation amount to the compressor (1) is increased, so that the discharge refrigerant temperature is prevented from momentarily excessive rise .

When the discharge refrigerant temperature detected by the discharge temperature detecting means (Th2) exceeds a predetermined temperature, the return means (54) stops the control of the fan forced operation means (53), so that the fan is operated. By the control means (52),
After the defrost ends , the operation of the outdoor fan (3a) is stopped until the stop time elapses. During this time, the rising speed of the high-pressure side pressure becomes slow, and the excessive increase of the high-pressure side pressure is prevented. .

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to FIGS.

FIG. 2 shows a refrigerant piping system of an air conditioner to which the present invention is applied. 4 way switching valve to replace, (3) is an outdoor fan (3a)
An outdoor heat exchanger functioning as a condenser during cooling operation and as an evaporator during heating operation, (4) a receiver for storing liquid refrigerant, (5) depressurizing function of refrigerant and adjusting refrigerant flow rate. An electric expansion valve having a function, (6) is an indoor heat exchanger that is installed indoors and functions as an evaporator during cooling operation, and as a condenser during heating operation, and (7) is a suction pipe of the compressor (1). This is an accumulator that is interposed and that removes the liquid refrigerant in the suction refrigerant.

The above-mentioned devices (1) to (7) are sequentially connected by a refrigerant pipe (8), and a refrigerant circuit (9) is constructed so that heat is transferred by circulating the refrigerant. Reference numeral (13) is a supercooling capillary tube provided on the liquid pipe side of the outdoor heat exchanger (3).

An oil recovery unit (10) for recovering the oil in the discharged refrigerant is provided on the discharge side of the compressor (1) of the refrigerant circuit (9). (10)
From the compressor to the suction pipe between the compressor (1) and the accumulator (7), an oil return passage (11) for returning the oil of the oil recovery device (10) to the suction side of the compressor (1) has a flow control valve (12). ) Is provided through.

In the liquid pipe of the refrigerant circuit (9), the receiver (4) and the electric expansion valve (5) are connected so that the electric expansion valve (5) communicates with the lower portion of the receiver (4), that is, the liquid portion. They are arranged in series on the common path (8a), and the common path (8a)
Only the flow of the refrigerant from the outdoor heat exchanger (3) to the receiver (4) is provided between the outdoor heat exchanger (3) and the point (P) which is the end on the upper side of the receiver (4) in a). The indoor heat exchanger (6) is connected between the point (P) of the common path (8a) and the indoor heat exchanger (6) by the first inflow path (8b) via the allowable first check valve (D1). 6) is connected to the second inflow passage (8c) via the second check valve (D2) that allows only the flow of the refrigerant from the receiver (4) to the receiver (4), while the common passage (8a) is electrically driven. Point (Q) which is the end on the other end side of the expansion valve (5) and the first check valve (D1) -outdoor heat exchanger (3)
A third check valve (D) that allows only the refrigerant to flow from the electric expansion valve (5) to the outdoor heat exchanger (3) between the point (S) and the point (S).
3) via the first outflow path (8d) to the common path (8
From the electric expansion valve (5) to the indoor heat exchanger (6) between the point (Q) in a) and the point (R) between the second check valve (D2) and the indoor heat exchanger (6). The second outflow passages (8e) are connected to each other via the fourth check valve (D4) that allows only the flow of the refrigerant to and from the refrigerant .

Further, one point (W) on the receiver upstream side of the common path (8a) and the fourth check valve (D) of the second outflow path (8e).
4) A liquid-sealing prevention bypass passage (8f) including a capillary tube (C) is provided between the upstream point (U) and the liquid when the compressor (1) is stopped. It is designed to prevent sealing.

Further, the air conditioner is provided with sensors, (Th2) is arranged in the discharge pipe of the compressor (1), and a discharge pipe as a discharge temperature detecting means for detecting the discharge refrigerant temperature T2. The sensor (Thc) is arranged in the liquid pipe of the outdoor heat exchanger (3) and detects the condensation temperature of the refrigerant during the cooling operation and the evaporation temperature of the refrigerant during the heating operation, (Tc).
ha) is arranged at the air inlet of the outdoor heat exchanger (3), an outside air temperature sensor for detecting the outside air temperature, (The) is arranged at the liquid pipe of the indoor heat exchanger (6), and the evaporation temperature during cooling operation. ,
An internal heat exchange sensor that detects the condensation temperature during heating operation (T
hr) is a room temperature sensor that is located at the air inlet of the indoor heat exchanger (6) and detects the temperature of the intake air. (HPS) is a high-pressure switch for protection that operates when the high-pressure side pressure reaches the upper limit and stops abnormally. (LPS) is a low pressure protective switch that operates and abnormally stops when the low pressure reaches the lower limit .

[0020] Then, the respective sensors, the controller for controlling the operation of the air conditioner is input connected (not shown) to the signal, by the controller, each device in response to the signal of the sensor Is designed to control the operation of.

In the refrigerant circuit (9), during cooling operation, the liquid refrigerant condensed and liquefied in the outdoor heat exchanger (3) flows from the first flow passage (8b) to the common passage (8a) and the receiver (4). After being decompressed by the electric expansion valve (5),
The circulation is returned to the compressor (1) by evaporating in the indoor heat exchanger (6) via the second outflow passage (8e) .

During the heating operation, the liquid refrigerant condensed and liquefied in the indoor heat exchanger (6) flows from the second flow passage (8c) to the common passage (8a) and is stored in the receiver (4).
After being decompressed by the electric expansion valve (5), the first outflow passage (8d)
After that, the heat is evaporated in the outdoor heat exchanger (3) and returned to the compressor (1) for circulation.

Next, the control contents of the controller during the heating operation will be described with reference to the flowchart of FIG. In step ST1, heating operation is performed in step ST2 until the frost signal based on the temperature Te of the outdoor heat exchanger (3) detected by the outdoor heat exchange sensor (Thc) is received, and when the frost signal is received, the step is performed. Proceed to ST3 to perform defrost operation. That is, the four-way switching valve (2) is turned off, that is, switched to the cooling cycle side, and the opening degree of the electric expansion valve (5) is substantially fully opened (for example, about 500 pulses when fully opened to about 480 pulses) to discharge the refrigerant into the outdoor heat The frost formation on the outdoor heat exchanger (3) is released by introducing it into the exchanger (3) .

On the other hand, in step ST4, the outside heat exchange temperature T
When e is recovered (for example, 10 ° C or higher) and a frost release command is output, the process proceeds to step ST5 and the four-way switching valve (2)
Is turned on, that is, the refrigerant circuit (9) is switched to the heating cycle to restart the heating operation. Subsequently , in step ST6, it is determined whether or not 20 seconds, which is the forced operation time, has elapsed after the end of defrost, and the process proceeds to step ST7 until 20 seconds after the end of defrost, the outdoor fan (3a).
On the other hand, when 20 seconds have passed after the end of defrost, the process proceeds to step ST8, and the discharge pipe sensor (T
discharge refrigerant temperature T2 detected by h2) it is determined whether or not higher than 60 ° C..

If T2> 60 (° C), the operation of the outdoor fan (3a) is continued as it is, and T2> 60.
When the temperature reaches (° C.), the process proceeds to step ST9 to stop the outdoor fan (3a), and in the determination of step ST10, after the defrosting is finished , the above control is performed until the stop time of 3 minutes elapses, and then step ST11. Operates the outdoor fan (3a) .

That is, the outdoor fan (3a) is operated to cool the refrigerant of the outdoor heat exchanger (3) until 20 seconds have elapsed after the heating operation is restarted, and the excessive rise of the discharged refrigerant temperature T2 is suppressed. On the other hand, T2> 60 after 20 seconds have passed
When the temperature reaches (° C.), it is determined that the excessive increase in the high pressure side pressure Hp and the discharge refrigerant temperature T2 has been resolved, and the outdoor fan (3
A) is stopped to suppress the decrease in heating efficiency.

Although the flow is omitted, during the defrosting operation, the opening degree of the electric expansion valve (5) is controlled to be almost fully opened in the normal state as described above. However, when the defrosting operation is completed, the outdoor heat exchanger (3) is approached. When the temperature Te becomes higher than 5 ° C., the opening degree of the electric expansion valve (5) is reduced (for example, to about 300 pulses) to remove the liquid refrigerant in the outdoor heat exchanger (3) and the liquid pipe from the receiver ( It is collected in 4) to prevent the liquid from returning to the compressor (1). By this control, the opening control means according to the present invention is configured.

In the above flow, the operation control means (51) according to the present invention is constituted by the control of step ST3, and the fan control means (52) is constituted by the control of steps ST9 to ST10. Also, step ST
By the control of 7, the fan forced operation means (53) is configured, and by the control of shifting from step ST8 to ST9,
Return means (54) is configured.

Therefore, in the above embodiment, when the outdoor heat exchanger (3) is frosted during the heating operation of the air conditioner, the defrost operation control means (51) causes the four-way switching valve (2) to move to the cooling cycle side. Then, the so-called reverse cycle defrost operation is performed, and when the defrosting is completed, the cycle is switched to the heating cycle again and the heating operation is performed. At that time, during the defrost operation, the opening control means normally controls the opening of the electric expansion valve (5) to be almost fully opened, but immediately before the end of the defrost operation, the compression at the time of heating recovery is performed. Since the opening of the electric expansion valve (5) is throttled to prevent liquid back to the machine (1), the refrigerant circuit (9) is pumped down, and the refrigerant is stored in the receiver ( 4 ).
The circulation amount of the refrigerant is reduced.

Next, the on / off of the outdoor fan (3a) and the change in the high pressure side pressure Hp after the defrosting operation will be described with reference to FIG. 4. When the defrosting operation is completed (time t0 in the figure), the fan is The control means (52) controls to stop the operation of the outdoor fan (3a) until a predetermined stop time (3 minutes in the above-mentioned embodiment) has elapsed after the defrost operation is completed. Due to the stop of the outdoor fan (3a), the high-temperature refrigerant accumulated in the outdoor heat exchanger (3) is sucked into the compressor (1), which is combined with the reduction of the refrigerant circulation amount as described above. The discharged refrigerant temperature T2 rapidly rises .

Here, in the above-described embodiment, the outdoor fan (3a) is forced to operate with a constant force by the forced fan operation means (53).
Since the operation is performed for more than the turning time (20 seconds in the above embodiment, time t1 in the figure), the evaporation amount of the refrigerant increases and the high pressure side pressure Hp rises during this time (time t0 to t1 in FIG. 4).
Since the liquid refrigerant in the outdoor heat exchanger (3) is cooled and the refrigerant circulation amount to the compressor (1) is increased, a momentary excessive rise in the discharged refrigerant temperature T2 is prevented.

On the other hand, when the discharge refrigerant temperature T2 detected by the discharge pipe sensor (Th2) exceeds the predetermined temperature (60 ° C.), the return means (54) causes the fan forced operation means (53).
Therefore, the fan control means (52) stops the operation of the outdoor fan (3a) until a predetermined stop time (3 minutes) elapses after the defrosting is completed, and during this time, the high pressure is stopped. The rising speed of the side pressure Hp becomes gentle (see time t2 to t3 in FIG. 4), and the excessive increase of the high pressure side pressure does not occur. That is, the discharge refrigerant temperature T2 at the time of switching to the heating operation after completion of the defrost operation
Can be prevented from rising and the high-pressure side pressure Hp can be prevented from rising excessively, so that the reliability can be improved.

[0033]

As described above, according to the present invention,
When the outdoor heat exchanger (3) is frosted during the heating operation, the reverse cycle defrost operation is performed, during which the opening of the electric expansion valve is controlled to be large and to be narrowed immediately before the end of the defrost operation,
After the defrost operation ends, the outdoor fan is stopped for a predetermined time and then the air conditioner operation controller is operated.The outdoor fan is forcibly operated for a certain forced operation time or more within the predetermined time after the defrost operation ends. Drive this
After the forced operation time has elapsed, if the temperature of the discharged refrigerant exceeds the predetermined temperature, the forced operation of the outdoor fan is stopped, so the refrigerant temperature of the outdoor heat exchanger decreases and the amount of evaporated refrigerant increases, so the discharged refrigerant While preventing an excessive rise in temperature, it is possible to suppress an excessive rise in pressure on the high-pressure side by stopping the operation of the outdoor fan after that, and thus it is possible to improve reliability.

[Brief description of drawings]

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

FIG. 2 is a refrigerant piping system diagram of an air conditioner according to an embodiment of the present invention.

FIG. 3 is a flowchart showing the control contents during heating operation.

FIG. 4 is a time chart showing ON / OFF of the outdoor fan and changes in the high-pressure side pressure after the end of the defrost operation.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Compressor 3 Outdoor heat exchanger 3a Outdoor fan 5 Electric expansion valve 6 Indoor heat exchanger 9 Refrigerant circuit 51 Defrost operation control means 52 Fan control means 53 Fan forced operation means 54 Return means Th2 Discharge pipe sensor (Discharge refrigerant temperature detection means) )

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shinichi Oka 1304 Kanaoka-machi, Sakai City, Osaka Prefecture Daikin Industrial Co., Ltd., Kanaoka Plant, Sakai Manufacturing Co., Ltd. (56) Reference JP 61-22161 (JP, A) Sho 64-3479 (JP, A)

Claims (1)

(57) [Claims] 1. A compressor, an outdoor heat exchanger (3) provided with an outdoor fan (3a), an electric expansion valve (5), and an indoor heat exchanger (6) are sequentially connected, and the cycle is switchable. In an air conditioner equipped with a refrigerant circuit (9) comprising the following, when the outdoor heat exchanger (3) is frosted during heating operation,
The above refrigerant circuit to perform reverse cycle defrost operation
(9) and the defrosting operation control means for controlling (51), the defrosting time of the reverse cycle defrosting operation by operation control means (51), said as narrowing the large and immediately before the end of the opening of the electric expansion valve (5) After the opening control means for controlling the electric expansion valve (5) and the defrost operation by the defrost operation control means (51) are finished, the outdoor fan (3a) is stopped until a predetermined stop time elapses , The room to drive
A fan control means (52 ) for controlling the outer fan (3a), and forcibly stopping the control of the fan control means (52) after the defrost operation by the defrost operation control means (51) is completed . At least the fan control means (52)
Until a certain forced operation time shorter than the stop time of
In a fan forced operation means (53) for driving the outdoor fan (3a), a discharge temperature detection means for detecting the discharge refrigerant temperature (Th2), receiving the output of said discharge temperature detecting means (Th2), Fan strong
After the forced operation time of the braking / controlling means (53) has elapsed, discharge
Fan forced operation means until the refrigerant temperature exceeds a predetermined temperature
The forced operation of the outdoor fan (3a) by (53) is continued.
And the stop time of the fan control means (52)
If the temperature of the discharged refrigerant exceeds the specified temperature by the time
The control of the forced fan operation means (53) is stopped and the fan
Returning means (54) for shifting to the control of the control means (52 )
Operation control device for an air-conditioning apparatus characterized by comprising and.