JPH11281123A - Air conditioner and method for switching four-way valve thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To securely switch a four-way valve without increasing operation capacity of a compressor. SOLUTION: In a four-way valve switching method of an air conditioner, compressors 16A through 16C, a four-way valve 18, and an outdoor heat exchanger are connected to an outdoor refrigerant pipe, an outdoor unit is provided wherein an outdoor fan 20 is installed to adjoin the outdoor heat exchanger, an indoor unit is provided wherein an indoor heat exchanger is connected to an indoor refrigerant pipe, and the outdoor refrigerant piping and the indoor refrigerant piping are connected to form a refrigerant circuit, the outdoor fan 20 is started at a timing slower than a timing to start the compressor from a state of stoppage, thereby switching the four-way valve simultaneously with starting the outdoor fan 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a four-way valve switching method for an air conditioner and an air conditioner for implementing the method.

[0002]

2. Description of the Related Art An air conditioner has an indoor heat exchange system with an outdoor unit in which a compressor, a four-way valve and an outdoor heat exchanger are arranged in an outdoor refrigerant pipe and an outdoor fan is arranged adjacent to the outdoor heat exchanger. Having 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 a compressor, a four-way valve, an outdoor fan, and the like are controlled by a control device to cool or heat the room.

[0003] By the way, during the heating operation of the air conditioner, when the outside air temperature falls to about 5 ° C or less, the refrigerant evaporation temperature of the outdoor heat exchanger becomes 0 ° C or less, and frost adheres to the outdoor heat exchanger. Therefore, it is necessary to appropriately perform a defrosting operation for removing the frost. This defrosting operation has various methods. As a reverse cycle defrosting method, as shown in FIG. 3, the four-way valve is switched from the heating position to the cooling position during the heating operation,
There is a type in which the operation of the outdoor fan is stopped, the high-temperature and high-pressure gas refrigerant from the compressor is led to an outdoor heat exchanger to which frost has adhered, and the frost that has adhered is melted by the heat of the refrigerant gas.

In the above-described defrosting operation, when the four-way valve is switched to the cooling position or the heating position while the compressor is operating, the pressure in the refrigerant pipe on the indoor unit side suddenly changes. Is transmitted to the indoor unit side. Therefore, at the start of the defrosting operation in which the four-way valve is switched from the heating position to the cooling position, and at the time of the return from the defrosting operation in which the four-way valve is switched from the cooling position to the heating position, the operation of the compressor is stopped and A method of switching the four-way valve after equalizing the refrigerant pressure in the circuit has been adopted.

In the above four-way valve switching method, when the defrosting operation is started, the start of the compressor and the switching of the four-way valve to the cooling position are performed at the same timing (time t1). . Further, when returning from the defrosting operation to the heating operation, activation of the compressor, switching of the four-way valve to the heating position, and activation of the indoor fan are performed at the same timing (time t2).

[0006]

However, the conventional method of switching the four-way valve in the above-described defrosting operation has the following problems. That is, 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 air conditioner is started and the outdoor fan is also started, it becomes low outdoor air cooling operation,
The air conditioner lowers the discharge pressure of the compressor so that the cooling operation capacity does not become 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 of the compressor and the suction-side refrigerant pressure acting on the four-way valve for performing the switching operation of the four-way valve) is sufficient. Is not secured
The four-way valve cannot be switched from the cooling position to the heating position in a short time (instantaneous).

In the worst case, the slide valve inside the four-way valve stops at the intermediate position between the cooling position and the heating position, and it becomes impossible to obtain the above-mentioned minimum operating differential pressure of the four-way valve. Depending on the four-way valve, switching to the cooling position and the heating position may not be possible.

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.

However, in this case, there is a possibility that the refrigerant temperature on the discharge side of the compressor abnormally rises or the refrigerant pressure on the suction side of the compressor becomes negative pressure, causing a low pressure cut.

An object of the present invention has been made in view of the above-mentioned circumstances, and a method of switching a four-way valve of an air conditioner capable of reliably switching a four-way valve without increasing the operating capacity of a compressor. And an air conditioner.

[0011]

According to the first aspect of the present invention,
A compressor, a four-way valve and an outdoor heat exchanger are disposed in the outdoor refrigerant pipe, and an outdoor unit in which an outdoor fan is disposed adjacent to the outdoor heat exchanger, and an indoor heat exchanger is disposed in the indoor refrigerant pipe. In the four-way valve switching method of the air conditioner, wherein the outdoor refrigerant pipe and the indoor refrigerant pipe are connected to form a refrigerant circuit, at a timing later than a timing at which the compressor starts from a stopped state. Further, the four-way valve is switched while the outdoor fan is stopped.

According to a second 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. A heat exchanger having an indoor unit disposed in the indoor refrigerant pipe, wherein the outdoor refrigerant pipe and the indoor refrigerant pipe are connected to form a refrigerant circuit in the four-way valve switching method of the air conditioner; The outdoor fan is activated at a timing later than the timing of starting from the stop state, and the four-way valve is switched at the same time as the activation of the outdoor fan or at a timing later than the activation of the outdoor fan.

According to a third aspect of the present invention, in the first aspect of the present invention, the defrosting operation is performed by switching the four-way valve from a heating position to a cooling position.

According to a fourth aspect of the present invention, in the second aspect of the invention, the four-way valve is switched from a cooling position to a heating position to return from the defrosting operation to the heating operation.

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. The heat exchanger has an indoor unit disposed in the indoor refrigerant pipe, and 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. In the air conditioner controlled by the device, the control device switches the four-way valve at a timing later than a timing at which the compressor starts from a stopped state and under a stopped state of the outdoor fan.

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. The heat exchanger has an indoor unit disposed in the indoor refrigerant pipe, and 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. In the air conditioner controlled by the device, the control device starts the outdoor fan at a timing later than the timing at which the compressor starts from a stopped state, and simultaneously with the start of the outdoor fan or the start of the outdoor fan. The four-way valve is switched at a timing later than the start.

The first to sixth aspects of the present invention have the following effects.

Starting the compressor from a stop 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 for switching the four-way valve is determined by the pressure difference of the four-way valve. Since it is possible to secure the pressure equal to or higher than the minimum operating differential pressure, the four-way valve can be reliably switched.

In addition, when the compressor is started, the outdoor fan is stopped, and the minimum operating differential pressure of the four-way valve is secured. Therefore, it is necessary to increase the operating capacity of the compressor in order to secure the minimum operating differential pressure of the four-way valve. There is no. For this reason, it is possible to prevent an abnormal rise in the refrigerant temperature on the discharge side of the compressor and a low pressure cut (negative pressure) phenomenon on the suction side of the compressor.

[0020]

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

FIG. 1 is a circuit diagram showing an air conditioner which implements an embodiment of a four-way valve switching method for an air conditioner according to the present invention.

As shown in FIG. 1, the air conditioner 10
Comprises an outdoor unit 11, a plurality of indoor units 12A, 12B... And a control device 13, and the outdoor refrigerant pipe 1 of the outdoor unit 11
Are connected to the indoor refrigerant pipes 15 of the indoor units 12A, 12B... To form a refrigerant circuit.

The outdoor unit 11 is installed outdoors, and variable capacity compressors 16A, 16B, 16C are arranged in parallel in the outdoor refrigerant pipe 14, and these compressors 16A, 16B, 16
An accumulator 17 is provided on the suction side of C, and a four-way valve 1 is provided on the discharge side.
8 is connected 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 the 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.

On the other hand, the indoor units 12A, 12B,... Are respectively installed indoors, and the indoor heat exchangers 21 are respectively disposed in the indoor refrigerant pipes 15. The expansion valve 22 is provided and configured. An indoor fan 23 for blowing air to the indoor heat exchanger 21 is disposed adjacent to the indoor heat exchanger 21.

The controller 13 controls the operation of the outdoor unit 11 and the indoor units 12A, 12B,..., Specifically, the compressors 16A to 16C, the four-way valve 18,
Outdoor fan 20, electric expansion valve 24, and indoor unit 12
A, 12B... Respectively control the electric expansion valve 22 and the indoor fan 23.

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, the control device 13 controls the four-way valve 1
8 is switched to the cooling side, the refrigerant flows as shown by the solid line arrow, and the outdoor heat exchanger 19 is connected to the condenser and the indoor heat exchanger 2
1 becomes an evaporator and enters a cooling operation state, and each indoor unit 12
A, 12B... Indoor heat exchangers 21 cool the room. When the control device 13 switches the four-way valve 18 to the heating side, the refrigerant flows as indicated by the dashed arrow and the indoor heat exchanger 21
.. Become a condenser, and the outdoor heat exchanger 19 becomes an evaporator to be in a heating operation state, and the indoor heat exchangers 21 of the indoor units 12A, 12B,.

The control unit 13 also controls the electric expansion valve 22 of the indoor unit 12A according to the air conditioning load of the indoor unit 12A.
Of the indoor fan 23 in the indoor unit 12A.
And the opening degree of the electric expansion valve 22 in the indoor unit 12B is adjusted according to the air conditioning load of the indoor unit 12B to control the indoor fan 23 in the indoor unit 12B. The control device 13 similarly controls other indoor units.

In the air conditioner 10 described above, when the outside air temperature drops to about 5 ° C. or less during the heating operation,
Since the evaporation temperature of the refrigerant in the outdoor heat exchanger 19 becomes 0 ° C. or less and frost adheres to the outdoor heat exchanger 19, it is necessary to appropriately perform a defrosting operation for removing the frost.

The control device 13 switches the four-way valve 18 from the heating position to the cooling position during the heating operation to stop the operation of the outdoor fan 20 and performs the operation of the compressor 1 to perform the defrosting operation.
The high-temperature and high-pressure gas refrigerant from 6A to 16C is guided to the outdoor heat exchanger 19 to which frost has adhered, and the frost adhering to the outdoor heat exchanger 19 is melted by the heat of the gas refrigerant.

The controller 13 controls the operations of the compressors 16A to 16C, the four-way valve 18, and the outdoor fan 20 as described below in the above-described defrosting operation.

That is, at time T1, the compressor 16A
16C and the operation of the outdoor fan 20 are stopped, and thereafter, when the defrosting operation is started at time T2, the compressors 16A to 16C are stopped.
C is activated, and at a time T3 after a lapse of a predetermined time X from the time T2, the four-way valve 18 is switched from the heating position (energized state) to the cooling position (non-energized state), and the air conditioner 10 performs the defrosting operation. Let it be implemented.

Thereafter, at the end of the defrosting operation, the control device 13 stops the operation of the compressors 16A to 16C at time T4, starts the compressors 16A to 16C at time T5, and keeps the compressors 16A to 16C for a certain period of time after this time T5. Y late time T6
At the same time, 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 started to return the air-conditioning apparatus 10 to the heating operation.

At time T1 before the above-described defrosting operation and at time T4 before returning to the heating operation, the compressors 16A to 16C
Is stopped until the pressure of the refrigerant in the refrigerant circuit of the air-conditioning apparatus 10 is substantially uniformed, whereby the refrigerant generated in the refrigerant circuit when the four-way valve 18 is switched is generated. A sudden change in pressure can be avoided.

At the time of returning from the defrosting operation to the heating operation, the compressors 16A to 16C are started at time T5, and then the four-way valve 18 is switched at time T6 which is later than the start timing, and at the same time, the outdoor fan is started. 20 is activated for the following reason.

That is, when returning to the heating operation, the four-way valve 18 is still at the cooling position, and the defrosting operation is performed when the outside air temperature is low. At this time, the compressor 16
When the outdoor fan 20 is started at the same time as the start of the A to 16C, the compressors 16A to 1C are controlled so that the cooling capacity does not become excessive.
In some cases, the refrigerant pressure on the discharge side of 6C decreases, and the minimum operating differential pressure of the four-way valve 18 (for example, about 3 kg / cm2) cannot be obtained. Here, when the four-way valve 18 is energized and de-energized, the switching operation cannot be performed if the difference between the refrigerant pressure on the discharge side and the refrigerant pressure on the suction side of the compressors 16A to 16C is less than the minimum operating differential pressure. Becomes Therefore, the control device 13 starts the outdoor fan 20 at a timing (time T6) later than the startup timing (time T5) of the compressors 16A to 16C, and during this time (the fixed time Y), the discharge side of the compressors 16A to 16C. And the pressure difference between the refrigerant pressure on the discharge side and the refrigerant pressure on the suction side of the compressors 16A to 16C is set to be equal to or higher than the minimum operating differential pressure of the four-way valve 18 (for example, about 5 to 10 kg / cm 2). It is switched from the cooling position to the heating position.

At the start of the defrosting operation, the four-way valve 18 is switched at a time T3 after a lapse of a predetermined time X after the compressors 16A to 16C are started with the outdoor fan 20 stopped (time T2). For the following reasons.

That is, even at the start of the defrosting operation, it is necessary for the four-way valve 18 to secure the minimum operating differential pressure. In this case, since the outdoor fan 20 is already in a stopped state, it is only necessary to wait X for a certain period of time after starting the compressors 16A to 16C.
The differential pressure of the refrigerant pressure between the discharge side and the suction side of the compressors 16A to 16C is equal to or higher than the minimum operating differential pressure of the four-way valve 18 (about 5 to 10 k).
g / cm2), and the four-way valve 18 can be switched from the heating position to the cooling position.

Therefore, according to the above embodiment, the following effects and advantages can be obtained.

Starting the compressors 16A to 16C from the stopped state When the compressors 16A to 16C are started (time T2, time T5), the outdoor fan 20 is stopped.
In order to switch the four-way valve 18, the pressure difference of the refrigerant in the refrigerant circuit acting on the four-way valve 18 (the differential pressure of the refrigerant pressure between the discharge side and the suction side of the compressors 16A to 16C) is determined by the minimum operation of the four-way valve 18. Since the pressure difference can be ensured, the four-way valve 18 can be switched reliably.

When the compressors 16A to 16C are started, the outdoor fan 20 is stopped and the minimum operating differential pressure of the four-way valve 18 is ensured. There is no need to increase the driving capability of the 16C. For this reason, it is possible to prevent the abnormal rise in 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.

Although the present invention has been described based on one embodiment, the present invention is not limited to this.

For example, in the above embodiment, when returning from the defrosting operation to the heating operation, the outdoor fan 20 is started at time T6, and at the same time, the four-way valve 18 is switched from the cooling position to the heating position. Alternatively, the outdoor fan 20 may be started at time T6, and then at time T7 after a certain time has elapsed, the four-way valve 18 may be switched from the cooling position to the heating position. However, also in this case, the compressor 1
The difference in refrigerant pressure between the discharge side and the suction side of 6A-16C is about 5
10 kg / cm 2) when switching the four-way valve 18 to prevent a sudden pressure change in the indoor refrigerant pipe 15 on the indoor units 12A, 12B,.

[0043]

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 outdoor fan is stopped at a later timing than when the compressor is started from a stopped state. Under the condition, the four-way valve is switched, 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 at the same time as the start of the outdoor fan. Since the fan is stopped, switching of the four-way valve can be reliably performed without increasing the operating capacity of the compressor.

[Brief description of the drawings]

FIG. 1 is a circuit diagram illustrating an air conditioner that implements an embodiment of a four-way valve switching method for an air conditioner according to the present invention.

FIG. 2 is a timing chart showing switching timing of a four-way valve in a defrosting operation in the air-conditioning apparatus of FIG.

FIG. 3 is a timing chart showing switching timings of four sides in a defrosting operation of the conventional air conditioner.

[Explanation of symbols]

 Reference Signs List 10 air conditioner 11 outdoor unit 12A, 12B indoor unit 13 controller 14 outdoor refrigerant pipe 15 indoor refrigerant pipe 16A, 16B, 16C compressor 18 four-way valve 19 outdoor heat exchanger 20 outdoor fan 21 indoor heat exchanger T2, T3, T5, T6 Time X constant time Y constant time

Claims (6)

[Claims] 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 arranged adjacent to the outdoor heat exchanger, and the indoor heat exchanger is an indoor refrigerant. An indoor unit disposed in a pipe, wherein the outdoor refrigerant pipe and the indoor refrigerant pipe are connected to form a refrigerant circuit in a four-way valve switching method for an air conditioner; At a later timing and under the stop condition of the outdoor fan,
A four-way valve switching method for an air conditioner, comprising switching the four-way valve. 2. An outdoor unit in which a compressor, a four-way valve and an outdoor heat exchanger are arranged in an outdoor refrigerant pipe, and an outdoor fan is disposed adjacent to the outdoor heat exchanger, and an indoor heat exchanger is an indoor refrigerant. An indoor unit disposed in a pipe, wherein the outdoor refrigerant pipe and the indoor refrigerant pipe are connected to form a refrigerant circuit in a four-way valve switching method for an air conditioner; Starting the outdoor fan at a later timing, and switching the four-way valve at the same time as the activation of the outdoor fan or at a timing later than the activation of the outdoor fan. . 3. The defrosting operation is performed by switching the four-way valve from a heating position to a cooling position.
4. The method for switching a four-way valve of an air conditioner according to item 1. 4. The four-way valve switching method for an air conditioner according to claim 2, wherein the four-way valve is switched from a cooling position to a heating position to return from the defrosting operation to the heating operation. 5. 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 the indoor heat exchanger is an indoor refrigerant. An indoor unit disposed in a pipe, wherein 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 starts from a stopped state and under a stopped state of the outdoor fan. 6. 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 the indoor heat exchanger is an indoor refrigerant. An indoor unit disposed in a pipe, wherein 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 harmony device, the control device activates the outdoor fan at a timing later than the timing at which the compressor starts from a stopped state, and simultaneously with the activation of the outdoor fan, or at a timing later than the activation of the outdoor fan. An air conditioner characterized by switching the four-way valve.