JP2000274892A - Air conditioner - Google Patents

Abstract

(57) [Problem] To provide an air conditioner in which a loss of heat radiation is reduced while performing continuous heating operation when an outdoor unit is defrosted, and a defrosting time is shortened. SOLUTION: It comprises a compressor 2, a four-way valve 3, an outdoor heat exchanger 5, an expansion valve 6, and an indoor heat exchanger 11, and these are sequentially connected by a refrigerant pipe to form a refrigerant circuit. In the air conditioner, a first solenoid valve 9a is disposed between the outdoor heat exchanger 5 and the four-way valve 3, and the first solenoid valve 9a and the outdoor heat exchanger 5 A first bypass passage 7a provided with a second solenoid valve 9b is provided between the discharge side of the machine 2 and the four-way valve 3, and the expansion valve is constituted by a first expansion valve 6a and a second expansion valve 6b; The first expansion valve 6a
Between the first expansion valve 6b and the four-way valve 3 and the first solenoid valve 9
A second bypass passage 7b provided with the third solenoid valve 9c and the defrosting heat exchanger 4 is disposed between the second bypass passage 7a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner and, more particularly, to the structure and control of a refrigerant circuit.

[0002]

2. Description of the Related Art FIG. 6 is a refrigerant circuit diagram of an air conditioner showing one example of the prior art, and FIG. 7 is a refrigerant circuit diagram of an air conditioner showing another example of the related art. As shown in the figure, a refrigerant circuit of a conventional air conditioner includes a compressor 2 housed in an outdoor unit 1, a four-way valve 3, an outdoor heat exchanger 5, and an expansion valve 6 housed in an indoor unit 10. And an indoor heat exchanger 11, which are sequentially connected to form a refrigerant circuit.

In the above configuration, during the cooling operation, the refrigerant flow in the outdoor unit 1 passes through the compressor 2 and the four-way valve 3 to the two-pass outdoor heat exchanger 5 as indicated by a broken line arrow. The refrigerant flows from the outdoor heat exchanger 3 via the expansion valve 6 into the indoor heat exchanger 11 of the indoor unit 10. Then, the refrigerant returns to the compressor 2 via the four-way valve 3 of the outdoor unit 1. Further, during the heating operation, the refrigerant flow path returns to the compressor 2 via the expansion valve 6 via a path opposite to that during the cooling as indicated by the solid arrow.

In order to defrost the outdoor unit 1 during heating, the four-way valve 3 is switched as shown in FIG.
As shown in FIG. 4, a reverse method performed by performing a cooling cycle, and, as shown in FIG. 4, a discharge gas from the compressor 2 is passed through a bypass pipe 7 and a solenoid valve 8 a to the expansion valve 6 side of the outdoor heat exchanger 5. There is a hot gas bypass system in which one end 5a is injected. However, in any of the above methods, since the high-temperature discharge gas is injected from the same point from the defrost start to the end regardless of the degree of melting of the frost, the frost immediately melts near the injection point, but the frost near the outlet exits. In order to melt the frost, the discharge gas must be continuously injected into the inlet where the frost has already melted. there were.

[0005]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, the present invention provides an air conditioner in which the loss of heat radiation is reduced when the outdoor unit is defrosted, and the defrosting time is reduced while performing the continuous heating operation. It is intended to provide.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and comprises a compressor, a four-way valve, an outdoor heat exchanger, an expansion valve, and an indoor heat exchanger. In an air conditioner configured by connecting these pipes sequentially with a refrigerant pipe to form a refrigerant circuit, a first solenoid valve is disposed between the outdoor heat exchanger and the four-way valve, and the first solenoid valve is provided. A first bypass having a second solenoid valve is provided between the outdoor heat exchanger and a discharge side of the compressor and a four-way valve, and the expansion valve is a first expansion valve and a second expansion valve. And between the first expansion valve and the second expansion valve, and between the four-way valve and the first solenoid valve, a second bypass path including a third solenoid valve and a defrosting heat exchanger. Be arranged.

During the cooling operation, the second solenoid valve is closed, the third solenoid valve is closed, the first solenoid valve is opened, the four-way valve is in the cooling mode, the first expansion valve is throttled, and the second expansion is performed. Control the valve fully open.

During the heating operation, the second solenoid valve is closed, the third solenoid valve is closed, the first solenoid valve is opened, the four-way valve is in the heating mode, the first expansion valve is throttled, and the second expansion valve is closed. Control the valve fully open.

During the defrosting operation, the second solenoid valve is opened, the third solenoid valve is opened, the first solenoid valve is closed, the four-way valve is in the heating mode, the first expansion valve is throttled, and the second solenoid valve is closed. The expansion valve is controlled to a throttle. Then, the opening degree of the second expansion valve is controlled so as to be wide at the time of the defrosting start and narrowed temporarily. Alternatively, the opening degree of the second expansion valve is controlled to be wider than the opening degree of the first expansion valve at the time of the defrosting start and to be temporarily reduced.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail based on embodiments with reference to the accompanying drawings. FIG.
FIG. 2 is a refrigerant circuit diagram of an air conditioner showing one embodiment of the present invention.
FIG. 3 is an explanatory view of a main part of an air conditioner showing one embodiment of the present invention, and FIG. 3 is a control flowchart of the air conditioner showing one embodiment of the present invention. The same numbers are used for the same components. In the figure, 1 is an outdoor unit,
2 is a compressor, 3 is a four-way valve, 4 is a defrosting heat exchanger, 5 is an outdoor heat exchanger, 6a is a first expansion valve, 6b is a second expansion valve, 9
b is a second solenoid valve, 9c is a third solenoid valve, 9a is a first solenoid valve, 10 is an indoor unit, 11 is an indoor heat exchanger, 21 is an outdoor unit control unit, and 22 is an indoor unit control unit.

This air conditioner comprises an outdoor unit 1 and an indoor unit 10.
And a compressor 2, a four-way valve 3,
It comprises an outdoor heat exchanger 5, an expansion valve 6, and an indoor heat exchanger 11, and these are sequentially connected by refrigerant pipes to form a refrigerant circuit. At the same time, the four-way valve 3 is switched to the cooling mode during cooling and the heating mode during heating to perform cooling and heating. Here, the air conditioner of the present invention includes a first solenoid valve 9a between the outdoor heat exchanger 5 and the four-way valve 3.
Is arranged. Further, a first bypass path 7a having a second electromagnetic valve 9b is provided between the first electromagnetic valve 9a and the outdoor heat exchanger 5 and between the discharge side of the compressor 2 and the four-way valve 3. .

On the other hand, the expansion valve comprises a first expansion valve 6a and a second expansion valve 6b. In addition, a third solenoid valve 9c and a defrosting heat exchanger 4 provided between the first expansion valve 6a and the second expansion valve 6b and between the four-way valve 3 and the first solenoid valve 9a. Two bypass paths 7b are provided.

The operation contents are inputted and stored by the input unit 23 and the storage unit 24, and the following control is performed by the indoor unit control unit 22 and the outdoor unit control unit 21. As shown in FIG. 3, it is determined whether a cooling operation is being performed (ST1). If Yes, the second solenoid valve 9b is closed, the third solenoid valve 9c is closed, the first solenoid valve 9a is opened, and the four-way valve is opened. 3 is a cooling mode, the first expansion valve 6a is throttled, and the second expansion valve 6b is fully opened.
(ST2) If No in ST1, it is determined whether or not a heating operation is being performed (ST3). If Yes, the second solenoid valve 9b is closed, the third solenoid valve 9c is closed, and the first solenoid valve 9a is closed. Open
The four-way valve 3 is controlled to the heating mode, the first expansion valve 6a is throttled, and the second expansion valve 6b is fully opened. (ST4) Further, if No in ST3, it is determined whether or not a defrosting operation is being performed (ST5), and if Yes, the second solenoid valve 9b is determined.
Is opened, the third solenoid valve 9c is opened, the first solenoid valve 9a is closed, the four-way valve 3 is controlled to the heating mode, the first expansion valve 6a is throttled, and the second expansion valve 6b is throttled. (ST6) If No in ST5, the process returns to the first ST1.

Next, the operation and effect of the embodiment of the present invention having the above configuration will be described. According to this embodiment,
During the cooling operation, the second solenoid valve 9b is closed, the third solenoid valve 9c is closed, the first solenoid valve 9a is opened, the four-way valve 3 is in the cooling mode, the first expansion valve 6a is throttled, and the second expansion is performed. Since the valve 6b is controlled to be fully open, the refrigerant flows along the path shown by the dotted line in the figure,
The indoor heat exchanger 11 serves as a low-pressure side evaporator, and the outdoor heat exchanger 5 serves as a high-pressure side condenser, thereby enabling cooling. Also,
During the heating operation, the second solenoid valve 9b is closed, the third solenoid valve 9c is closed, the first solenoid valve 9a is opened, the four-way valve 3 is in the heating mode, the first expansion valve 6a is throttled, and the second expansion is performed. Since the valve 6b is controlled to be fully open, the refrigerant flows along the path shown by the solid line in the figure,
The indoor heat exchanger 11 functions as a high-pressure side condenser, and the outdoor heat exchanger 5 functions as a low-pressure side evaporator, thereby enabling heating.

On the other hand, during the defrosting operation, the second solenoid valve 9b
Is opened, the third solenoid valve 9c is opened, the first solenoid valve 9a is closed, the four-way valve 3 is controlled to the heating mode, the first expansion valve 6a is throttled, and the second expansion valve 6b is throttled. The refrigerant flows along a path shown by a thick solid line in the figure, and the outdoor heat exchanger 5 becomes a high-pressure side condenser together with the indoor heat exchanger 11, and defrosting is performed in a short time in a continuous heating operation. In this case, the defrosting heat exchanger 4 is an evaporator.

FIG. 4 is an explanatory view of the operation of the main part of an air conditioner showing another embodiment of the present invention. In the case of this embodiment, the opening degree of the second expansion valve 6b is controlled so as to be wide at the time of the defrosting start and to be temporarily reduced.

Next, the operation and effect of another embodiment of the present invention will be described. According to this embodiment, the second expansion valve 6
Since the opening degree of b is widened at the time of the defrost start, a large amount of refrigerant flows to the outdoor heat exchanger 5, so that the initial defrost can be performed more quickly and in a shorter time. Since the opening degree of the first expansion valve 6a is constant, defrosting is performed without lowering the continuous heating operation performance, and when defrosting is completed, the operation can be shifted to the heating-only operation without a sense of incongruity.

FIG. 5 is an explanatory diagram of an operation of a main part of an air conditioner showing another embodiment of the present invention. In the case of this embodiment, the opening degree of the second expansion valve 6b is controlled to be wider than the opening degree of the first expansion valve 6a at the time of the defrosting start and to be narrowed temporarily.

Next, the operation and effect of another embodiment of the present invention will be described. According to this embodiment, the second expansion valve 6
b from the opening of the first expansion valve 6a.
At this time, since more refrigerant flows through the outdoor heat exchanger 5 than the indoor heat exchanger 11, initial defrost can be performed more quickly and in a shorter time. And defrost star
Although the continuous heating operation performance is slightly reduced only at the time of defrosting, the defrosting is performed with a larger amount of the refrigerant in the continuous heating operation performance.

[0020]

As described above, according to the present invention, the compressor, the four-way valve, the outdoor heat exchanger, the expansion valve, and the indoor heat exchanger are connected sequentially by refrigerant pipes. In the air conditioner comprising a refrigerant circuit, a first solenoid valve is disposed between the outdoor heat exchanger and the four-way valve, and between the first solenoid valve and the outdoor heat exchanger, A first bypass including a second solenoid valve is disposed between the discharge side of the compressor and the four-way valve, and the expansion valve is configured by a first expansion valve and a second expansion valve. Between the second expansion valve and
A second bypass including a third solenoid valve and a defrosting heat exchanger is provided between the four-way valve and the first solenoid valve.

As a result, it is possible to provide an outdoor unit of an air conditioner in which the loss of heat radiation is reduced while performing the continuous heating operation, the defrosting time is shortened, and the low-temperature heating capacity and the comfort are improved.

[Brief description of the drawings]

FIG. 1 is a refrigerant circuit diagram of an air conditioner showing one embodiment of the present invention.

FIG. 2 is an explanatory view of a main part of an air conditioner showing one embodiment of the present invention.

FIG. 3 is a control flowchart of the air conditioner showing one embodiment of the present invention.

FIG. 4 is an explanatory diagram of an operation of a main part of an air conditioner according to another embodiment of the present invention.

FIG. 5 is an operation explanatory view of a main part of an air conditioner showing another embodiment of the present invention.

FIG. 6 is a refrigerant circuit diagram of an air conditioner showing an example of the related art.

FIG. 7 is a refrigerant circuit diagram of an air conditioner showing another conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Outdoor unit 2 Compressor 3 Four-way valve 4 Heat exchanger for defrosting 5 Outdoor heat exchanger 6a First expansion valve 6b Second expansion valve 7a First bypass path 7b Second bypass path 9a First electromagnetic valve 9b Second electromagnetic Valve 9c Third solenoid valve 10 Indoor unit 11 Indoor heat exchanger 21 Outdoor unit control unit 22 Indoor unit control unit

Claims (6)

[Claims] 1. A compressor, a four-way valve, an outdoor heat exchanger,
An air conditioner comprising an expansion valve and an indoor heat exchanger, which are sequentially connected by refrigerant pipes to form a refrigerant circuit, wherein a first electromagnetic valve is provided between the outdoor heat exchanger and the four-way valve. And a first bypass having a second solenoid valve between the first solenoid valve and the outdoor heat exchanger, and a discharge side of the compressor and a four-way valve, and The valve comprises a first expansion valve and a second expansion valve, between the first expansion valve and the second expansion valve, between the four-way valve and the first solenoid valve, a third solenoid valve and defrosting An air conditioner comprising a second bypass provided with a heat exchanger. 2. During a cooling operation, the second solenoid valve is closed,
2. The control system according to claim 1, wherein the third solenoid valve is closed, the first solenoid valve is opened, the four-way valve is controlled in the cooling mode, the first expansion valve is throttled, and the second expansion valve is fully opened. Air conditioner. 3. During a heating operation, the second solenoid valve is closed,
2. The method according to claim 1, wherein the third solenoid valve is closed, the first solenoid valve is opened, the four-way valve is controlled to the heating mode, the first expansion valve is throttled, and the second expansion valve is fully opened. Air conditioner. 4. During the defrosting operation, the second solenoid valve is opened,
2. The method according to claim 1, wherein the third solenoid valve is opened, the first solenoid valve is closed, the four-way valve is controlled to a heating mode, the first expansion valve is throttled, and the second expansion valve is throttled. Air conditioner. 5. The air conditioner according to claim 4, wherein the degree of opening of the second expansion valve is controlled so as to be wide at the time of the defrosting start and to be narrowed temporarily. 6. The control method according to claim 4, wherein the opening degree of the second expansion valve is controlled to be wider than the opening degree of the first expansion valve at the time of defrosting start and to be temporarily reduced. Air conditioner.