JP3778687B2 - Four-way valve switching method for air conditioner and air conditioner - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a four-way valve switching method for an air conditioner and an air conditioner for carrying out the method.
[0002]
[Prior art]
The air conditioner includes an outdoor unit in which a compressor, a four-way valve, and an outdoor heat exchanger are arranged in an outdoor refrigerant pipe, an outdoor fan adjacent to the outdoor heat exchanger, and an indoor heat exchanger in the indoor refrigerant pipe. The indoor refrigerant pipe and the indoor refrigerant pipe are connected to form a refrigerant circuit, and the compressor, the four-way valve, the outdoor fan, etc. are controlled by the control device to cool the room or It is for heating.
[0003]
By the way, during the heating operation of the air conditioner, if the outside air temperature falls to about 5 ° C. or less, the evaporation temperature of the refrigerant in the outdoor heat exchanger becomes 0 ° C. or less, and frost adheres to the outdoor heat exchanger. It is necessary to appropriately perform a defrosting operation for removing frost. There are various types of defrosting operation, but as a reverse cycle defrosting method, as shown in FIG. 3, during the heating operation, the four-way valve is switched from the heating position to the cooling position, the operation of the outdoor fan is stopped, and the compression is performed. Some high-temperature, high-pressure gas refrigerants from the machine are led to an outdoor heat exchanger with frost attached, and the frost attached with the heat of the refrigerant gas is removed.
[0004]
In the defrosting operation described above, if the four-way valve is switched to the cooling position or the heating position while the compressor is operating, the pressure changes suddenly in the refrigerant pipe on the indoor unit side, and the difference caused by this sudden pressure change. Sound is transmitted to the indoor unit. Therefore, at the start of the defrosting operation for switching the four-way valve from the heating position to the cooling position and at the return from the defrosting operation for switching the four-way valve from the cooling position to the heating position to the heating operation, the operation of the compressor is stopped and the refrigerant is stopped. A method of switching the four-way valve after equalizing the refrigerant pressure in the circuit is employed.
[0005]
Further, in the above four-way valve switching method, at the start of the defrosting operation, the compressor is started and the four-way valve is switched to the cooling position at the same timing (time t1). Furthermore, at the time of returning from the defrosting operation to the heating operation, the compressor is started, the four-way valve is switched to the heating position, and the indoor fan is started at the same timing (time t2).
[0006]
[Problems to be solved by the invention]
However, the four-way valve switching method in the conventional defrosting operation as described above has the following problems. In other words, especially when returning from the defrosting operation to the heating operation, the four-way valve is still in the cooling position and the defrosting operation is performed when the outside air temperature is low. When the machine is started and the outdoor fan is also started, a low outdoor air cooling operation is performed, and the air conditioner reduces the discharge pressure of the compressor so that the cooling operation capability is not excessive. As a result, the minimum operating differential pressure of the four-way valve (that is, the differential pressure between the discharge-side refrigerant pressure and the suction-side refrigerant pressure acting on the four-way valve to perform the switching operation of the four-way valve) is sufficient. The four-way valve cannot be switched from the cooling position to the heating position in a short time (instant).
[0007]
In the worst case, the slide valve inside the four-way valve stops at an intermediate position between the cooling position and the heating position, and the minimum operating differential pressure of the four-way valve cannot be obtained. May be unable to be switched to the cooling position or the heating position.
[0008]
Therefore, it is conceivable to forcibly switch the four-way valve by increasing the operating capacity of the compressor when switching the four-way valve and increasing the refrigerant pressure on the discharge side of the compressor.
[0009]
However, in this case, the refrigerant temperature on the discharge side of the compressor may rise abnormally, or the refrigerant pressure on the suction side of the compressor may become negative and a low pressure cut may occur.
[0010]
An object of the present invention has been made in consideration of the above-described circumstances, and a four-way valve switching method and an air conditioner for an air conditioner that can reliably switch the four-way valve without increasing the operation capacity of the compressor. To provide an apparatus.
[0011]
[Means for Solving the Problems]
According to the first aspect of the present invention, an outdoor unit in which a compressor, a four-way valve, and an outdoor heat exchanger are disposed in an outdoor refrigerant pipe, and an outdoor fan is disposed adjacent to the outdoor heat exchanger, and an indoor heat exchanger are provided. In the four-way valve switching method of the air conditioner in which the outdoor refrigerant pipe and the indoor refrigerant pipe are connected to form a refrigerant circuit. The four-way valve is switched at a timing later than the start timing and when the outdoor fan is stopped.
[0012]
The invention according to claim 2 is an outdoor unit in which a compressor, a four-way valve, and an outdoor heat exchanger are disposed in an outdoor refrigerant pipe, and an outdoor fan is disposed adjacent to the outdoor heat exchanger, and an indoor heat exchanger In the four-way valve switching method of the air conditioner in which the outdoor refrigerant pipe and the indoor refrigerant pipe are connected to form a refrigerant circuit. The outdoor fan is activated at a timing later than the activation timing, and the four-way valve is switched simultaneously with the activation of the outdoor fan or at a timing later than the activation of the outdoor fan.
[0013]
According to a third aspect of the invention, in the first aspect of the invention, the four-way valve is switched from the heating position to the cooling position to perform the defrosting operation.
[0014]
The invention according to claim 4 is the invention according to claim 2, wherein the four-way valve is switched from the cooling position to the heating position to return from the defrosting operation to the heating operation.
[0015]
According to a fifth aspect of the present invention, there is provided an outdoor unit in which a compressor, a four-way valve, and an outdoor heat exchanger are disposed in an outdoor refrigerant pipe, and an outdoor fan is disposed adjacent to the outdoor heat exchanger, and an indoor heat exchanger Has an indoor unit disposed in the indoor refrigerant pipe, the outdoor refrigerant pipe and the indoor refrigerant pipe are connected to form a refrigerant circuit, and the compressor, the four-way valve, and the outdoor fan are controlled by a control device. In the air conditioner, the control device switches the four-way valve at a timing later than a timing at which the compressor is started from a stopped state and when the outdoor fan is stopped.
[0016]
According to a sixth aspect of the present invention, there is provided an outdoor unit in which a compressor, a four-way valve, and an outdoor heat exchanger are disposed in an outdoor refrigerant pipe, and an outdoor fan is disposed adjacent to the outdoor heat exchanger, and an indoor heat exchanger Has an indoor unit disposed in the indoor refrigerant pipe, the outdoor refrigerant pipe and the indoor refrigerant pipe are connected to form a refrigerant circuit, and the compressor, the four-way valve, and the outdoor fan are controlled by a control device. In the air conditioner to be operated, the control device activates the outdoor fan at a timing later than the timing at which the compressor is activated from a stopped state, and simultaneously with the activation of the outdoor fan or more than the activation of the outdoor fan. The four-way valve is switched at a late timing.
[0017]
The invention described in claims 1 to 6 has the following action.
[0018]
Starting the compressor from the stopped state Since the outdoor fan is stopped when the compressor is started, the pressure difference of the refrigerant in the refrigerant circuit acting on the four-way valve to switch the four-way valve is set to the minimum operating difference of the four-way valve. Since the pressure can be secured above the pressure, the four-way valve can be switched reliably.
[0019]
Further, since the outdoor fan is stopped when the compressor is started and the minimum operating differential pressure of the four-way valve is ensured, it is not necessary to increase the operating capacity of the compressor in order to ensure the minimum operating differential pressure of the four-way valve. For this reason, the abnormal rise of the refrigerant temperature on the discharge side of the compressor and the occurrence of the low pressure cut (negative pressure) phenomenon on the suction side of the compressor can be prevented.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0021]
FIG. 1 is a circuit diagram showing an air conditioner for carrying out an embodiment of a four-way valve switching method for an air conditioner according to the present invention.
[0022]
As shown in FIG. 1, the air conditioner 10 includes an outdoor unit 11, a plurality of indoor units 12A, 12B,... And a control device 13, and includes an outdoor refrigerant pipe 14 and the indoor units 12A, 12B of the outdoor unit 11. Are connected to the indoor refrigerant pipe 15 to form a refrigerant circuit.
[0023]
The outdoor unit 11 is installed outdoors, variable capacity compressors 16A, 16B, and 16C are arranged in parallel to the outdoor refrigerant pipe 14, and an accumulator 17 is discharged to the suction side of these compressors 16A, 16B, and 16C. A four-way valve 18 is connected to each side via an outdoor refrigerant pipe 14, and an outdoor heat exchanger 19 and an electric expansion valve 24 are connected to the four-way valve 18 via an outdoor refrigerant pipe 14. An outdoor fan 20 that blows air toward the outdoor heat exchanger 19 is disposed adjacent to the outdoor heat exchanger 19.
[0024]
On the other hand, each of the indoor units 12A, 12B,... Is installed indoors, and an indoor heat exchanger 21 is provided in the indoor refrigerant pipe 15, and an electric expansion valve 22 is provided in the vicinity of the indoor heat exchanger 21 in the indoor refrigerant pipe 15. Is arranged. An indoor fan 23 that blows air to the indoor heat exchanger 21 is disposed adjacent to the indoor heat exchanger 21.
[0025]
Further, the control device 13 controls the operation of the outdoor unit 11 and the indoor units 12A, B,..., Specifically, the compressors 16A to 16C, the four-way valve 18, the outdoor fan 20, and the electric expansion valve in the outdoor unit 11. 24, and the electric expansion valve 22 and the indoor fan 23 in the indoor units 12A, 12B.
[0026]
When the four-way valve 18 is switched by the control device 13, the air conditioner 10 is set to the cooling operation or the heating operation. That is, when the control device 13 switches the four-way valve 18 to the cooling side, the refrigerant flows as indicated by solid arrows, the outdoor heat exchanger 19 becomes the condenser, and the indoor heat exchanger 21 becomes the evaporator, and the cooling operation state is entered. The indoor heat exchanger 21 of each indoor unit 12A, 12B, ... cools the room. Further, when the control device 13 switches the four-way valve 18 to the heating side, the refrigerant flows as indicated by the broken arrow, the indoor heat exchanger 21 becomes a condenser, and the outdoor heat exchanger 19 becomes an evaporator to enter a heating operation state. The indoor heat exchanger 21 of the indoor units 12A, 12B, ... heats the room.
[0027]
Further, the control device 13 adjusts the opening degree of the electric expansion valve 22 in the indoor unit 12A according to the air conditioning load of the indoor unit 12A, controls the indoor fan 23 in the indoor unit 12A, and air-conditions the indoor unit 12B. According to the load, the opening degree of the electric expansion valve 22 in the indoor unit 12B is adjusted to control the indoor fan 23 in the indoor unit 12B. The control device 13 similarly controls other indoor units.
[0028]
In the air conditioner 10 described above, when the outside air temperature drops to about 5 ° C. or lower during heating operation, the refrigerant evaporation temperature in the outdoor heat exchanger 19 becomes 0 ° C. or lower, and the outdoor heat exchanger 19 Since frost adheres, it is necessary to appropriately perform a defrosting operation for removing the frost.
[0029]
In order to perform the defrosting operation, the control device 13 switches the four-way valve 18 from the heating position to the cooling position during the heating operation, stops the operation of the outdoor fan 20, and performs high-temperature and high-pressure gas refrigerant from the compressors 16A to 16C. Is led to the outdoor heat exchanger 19 to which frost is attached, and the frost attached to the outdoor heat exchanger 19 is melted by the heat of the gas refrigerant.
[0030]
In the above-described defrosting operation, the control device 13 controls the operations of the compressors 16A to 16C, the four-way valve 18 and the outdoor fan 20 as follows, as shown in FIG.
[0031]
That is, at time T1, the operations of the compressors 16A to 16C and the outdoor fan 20 are stopped, and then the compressors 16A to 16C are started at the start of the defrosting operation at time T2, and the time after a certain time X has elapsed from this time T2. At T3, the four-way valve 18 is switched from the heating position (energized state) to the cooling position (non-energized state) to cause the air conditioner 10 to perform the defrosting operation.
[0032]
Thereafter, at the end of the defrosting operation, the control device 13 stops the operation of the compressors 16A to 16C at the time T4, starts the compressors 16A to 16C at the time T5, and is a time later than the time T5 by a certain time Y. At T6, the four-way valve 18 is switched from the cooling position to the heating position, and at the same time, the outdoor fan 20 is activated to return the air conditioner 10 to the heating operation.
[0033]
The reason for stopping the operation of the compressors 16A to 16C at the time T1 before the defrosting operation and the time T4 before returning to the heating operation is that the refrigerant pressure is almost uniform in the refrigerant circuit of the air conditioner 10. Therefore, it is possible to avoid a sudden change in the refrigerant pressure in the refrigerant circuit that occurs when the four-way valve 18 is switched.
[0034]
When returning from the defrosting operation to the heating operation, the compressors 16A to 16C are activated at time T5, and then the four-way valve 18 is switched at time T6, which is later than the activation timing, and the outdoor fan 20 is activated at the same time. The reason is as follows.
[0035]
That is, when returning to the heating operation, the four-way valve 18 is still in the cooling position, and the defrosting operation is performed when the outside air temperature is low. At this time, if the outdoor fan 20 is activated simultaneously with the activation of the compressors 16A to 16C, the refrigerant pressure on the discharge side of the compressors 16A to 16C is reduced so that the cooling capacity is not excessive, and the minimum operation of the four-way valve 18 is performed. A differential pressure (for example, about 3 kg / cm 2) may not be obtained. Here, the four-way valve 18 cannot be switched when the difference between the refrigerant pressure on the discharge side and the refrigerant pressure on the suction side of the compressors 16 </ b> A to 16 </ b> C is equal to or less than the minimum operating differential pressure when energized or not energized. It becomes. Therefore, the control device 13 activates the outdoor fan 20 at a timing (time T6) later than the activation timing (time T5) of the compressors 16A to 16C, and during this time (constant time Y), the discharge side of the compressors 16A to 16C The refrigerant pressure of the compressors 16A to 16C is increased so that the pressure difference between the refrigerant pressures on the discharge side and the suction side of the compressors 16A to 16C is greater than or equal to the minimum operating differential pressure of the four-way valve 18 (for example, about 5 to 10 kg / cm2). Switching from the cooling position to the heating position.
[0036]
Further, at the start of the defrosting operation, the four-way valve 18 is switched at the time T3 after the lapse of the predetermined time X after the start of the compressors 16A to 16C (time T2) with the outdoor fan 20 stopped. Depending on the reason.
[0037]
That is, even when the defrosting operation is started, the four-way valve 18 needs to ensure a minimum operating differential pressure. In this case, since the outdoor fan 20 is already stopped, the pressure difference between the refrigerant pressures on the discharge side and the suction side of the compressors 16A to 16C can be determined only by waiting for a certain time X after the compressors 16A to 16C are started. However, it becomes more than the minimum operating differential pressure of the four-way valve 18 (about 5 to 10 kg / cm 2), and the four-way valve 18 can be switched from the heating position to the cooling position.
[0038]
Therefore, according to the above embodiment, the following effects (1) and (2) are achieved.
[0039]
(1) Start the compressors 16A to 16C from the stopped state Since the outdoor fan 20 is stopped when the compressors 16A to 16C are started (time T2, time T5), the four-way valve 18 is switched to switch the four-way valve 18. Since the pressure difference of the refrigerant in the refrigerant circuit acting on the valve 18 (the pressure difference of the refrigerant pressure between the discharge side and the suction side of the compressors 16A to 16C) can be ensured more than the minimum operating differential pressure of the four-way valve 18, the four-way The valve 18 can be switched reliably.
[0040]
(2) Since the outdoor fan 20 is stopped and the minimum operating differential pressure of the four-way valve 18 is ensured when the compressors 16A to 16C are started, the compressors 16A to 16A to ensure the minimum operating differential pressure of the four-way valve 18 There is no need to increase the driving capacity of 16C. For this reason, the abnormal rise of the refrigerant temperature on the discharge side of the compressors 16A to 16C and the occurrence of the low pressure cut phenomenon due to the negative pressure on the suction side of the compressors 16A to 16C can be prevented.
[0041]
As mentioned above, although this invention was demonstrated based on one Embodiment, this invention is not limited to this.
[0042]
For example, in the above-described embodiment, when the outdoor fan 20 is activated at the time T6 when the defrosting operation is returned to the heating operation, the four-way valve 18 is switched from the cooling position to the heating position at the time T6. The outdoor fan 20 may be activated at, and the four-way valve 18 may be switched from the cooling position to the heating position at time T7 after a predetermined time has elapsed. However, also in this case, the difference between the refrigerant pressures on the discharge side and the suction side of the compressors 16A to 16C is about 5 to 10 kg / cm 2), and the indoor units 12A, 12B,. It is necessary to prevent sudden pressure fluctuations in the refrigerant pipe 15.
[0043]
【The invention's effect】
As described above, according to the four-way valve switching method and the air conditioner of the air conditioner according to the present invention, the four-way valve is operated at a timing later than the timing at which the compressor is started from the stopped state and under the stopped state of the outdoor fan. Or the outdoor fan is started at a timing later than the timing when the compressor is started from the stopped state, and the four-way valve is switched simultaneously with the start of the outdoor fan, so that the outdoor fan is stopped when the compressor is started. Therefore, the four-way valve can be switched reliably without increasing the operation capacity of the compressor.
[Brief description of the drawings]
FIG. 1 is a circuit diagram showing an air conditioner for carrying out an embodiment of a four-way valve switching method for an air conditioner according to the present invention.
2 is a timing chart showing the switching timing of the four-way valve in the defrosting operation in the air conditioner of FIG. 1. FIG.
FIG. 3 is a timing chart showing switching timings in four directions in a defrosting operation of a conventional air conditioner.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Air conditioning apparatus 11 Outdoor unit 12A, 12B Indoor unit 13 Control apparatus 14 Outdoor refrigerant piping 15 Indoor refrigerant piping 16A, 16B, 16C Compressor 18 Four-way valve 19 Outdoor heat exchanger 20 Outdoor fan 21 Indoor heat exchangers T2, T3, T5, T6 Time X Fixed time Y Fixed time

Claims (6)

A compressor, a four-way valve, and an outdoor heat exchanger are disposed in the outdoor refrigerant pipe, an outdoor unit in which an outdoor fan is disposed adjacent to the outdoor heat exchanger, and an indoor heat exchanger are disposed in the indoor refrigerant pipe. In the four-way valve switching method of the air conditioner, in which the outdoor refrigerant pipe and the indoor refrigerant pipe are connected to form a refrigerant circuit.
A four-way valve switching method for an air conditioner, wherein the four-way valve is switched at a timing later than a timing at which the compressor is started from a stopped state and under a stopped state of the outdoor fan. A compressor, a four-way valve, and an outdoor heat exchanger are disposed in the outdoor refrigerant pipe, an outdoor unit in which an outdoor fan is disposed adjacent to the outdoor heat exchanger, and an indoor heat exchanger are disposed in the indoor refrigerant pipe. In the four-way valve switching method of the air conditioner, in which the outdoor refrigerant pipe and the indoor refrigerant pipe are connected to form a refrigerant circuit.
Start the outdoor fan at a timing later than the timing when the compressor starts from a stopped state,
A four-way valve switching method for an air conditioner, wherein the four-way valve is switched simultaneously with the activation of the outdoor fan or at a timing later than the activation of the outdoor fan. The four-way valve switching method for an air conditioner according to claim 1, wherein the defrosting operation is performed by switching the four-way valve from a heating position to a cooling position. The four-way valve switching method for an air conditioner according to claim 2, wherein the four-way valve is switched from the cooling position to the heating position to return from the defrosting operation to the heating operation. A compressor, a four-way valve, and an outdoor heat exchanger are disposed in the outdoor refrigerant pipe, an outdoor unit in which an outdoor fan is disposed adjacent to the outdoor heat exchanger, and an indoor heat exchanger are disposed in the indoor refrigerant pipe. An air conditioner in which the outdoor refrigerant pipe and the indoor refrigerant pipe are connected to form a refrigerant circuit, and the compressor, the four-way valve, and the outdoor fan are controlled by a control device.
The air conditioner characterized in that the control device switches the four-way valve at a timing later than a timing at which the compressor is started from a stopped state and under a stopped state of the outdoor fan. A compressor, a four-way valve, and an outdoor heat exchanger are disposed in the outdoor refrigerant pipe, an outdoor unit in which an outdoor fan is disposed adjacent to the outdoor heat exchanger, and an indoor heat exchanger are disposed in the indoor refrigerant pipe. An air conditioner in which the outdoor refrigerant pipe and the indoor refrigerant pipe are connected to form a refrigerant circuit, and the compressor, the four-way valve, and the outdoor fan are controlled by a control device.
The control device activates the outdoor fan at a timing later than a timing at which the compressor starts from a stopped state, and simultaneously with activation of the outdoor fan or at a timing later than activation of the outdoor fan, the four-way valve An air conditioner that switches between the above.

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