JP2001355931A - Heat pump type air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat pump type air conditioner to enable prevention of liquid back during a stop of operation of the air conditioner or eliminate a need for an external save circuit. SOLUTION: The heat pump type air conditioner is provided with a compressor 3, an outdoor heat exchanger 9, an outdoor expansion valve 10, an indoor expansion valve 7, an indoor heat exchanger 5, and a four-way valve 11. The four-way valve 11 is constituted such that a valve can be switched even when an operation differential pressure is not generated. During a stop of operation, the outdoor expansion valve 10 and the indoor expansion valve 7 are fully closed and a control means 57 is provided to make the low pressure side and the high pressure side uniform with each other by switching the four-way valve 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat pump type air conditioner using a non-azeotropic mixed refrigerant composed of, for example, a high-boiling refrigerant and a low-boiling refrigerant.

[0002]

2. Description of the Related Art Generally, a heat pump type air conditioner including a compressor, an outdoor heat exchanger, an outdoor expansion valve, an indoor expansion valve, and an indoor heat exchanger is known. In this kind of thing,
In general, an accumulator is connected to a suction pipe of a compressor, and a liquid refrigerant is stored in the accumulator to prevent liquid back to the compressor.

However, when a non-azeotropic mixed refrigerant composed of a high-boiling refrigerant and a low-boiling refrigerant is used as the refrigerant, when the refrigerant enters the accumulator, it is vaporized from the low-boiling refrigerant and sucked into the compressor. There is a problem that much remains in the accumulator. In this case, the liquid amount of the low-boiling refrigerant increases in the refrigerant circuit, and the ratio between the high-boiling refrigerant and the low-boiling refrigerant in the non-azeotropic mixed refrigerant fluctuates with respect to a predetermined value. There is a risk.

In order to solve this problem, a technique has been proposed in which the outdoor expansion valve and the indoor expansion valve are controlled without providing the accumulator to prevent the liquid from flowing back to the compressor. Have been.

[0005]

However, the prior art can prevent liquid back to the compressor during operation or start-up of the air conditioner, but prevents liquid back during operation stop. There is a problem that you can not.

On the other hand, in the prior art, a discharge pipe and a suction pipe of the compressor are connected by an external save circuit, and if necessary, a part of the refrigerant discharged from the compressor is compressed through the external save circuit. It may be returned to the suction pipe of the unit, and the capacity control of the outdoor unit may be executed. In this case, there is a problem that an external save circuit is required and a control means is required, which causes an increase in manufacturing cost.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and is intended to prevent a liquid back when the operation of an air conditioner is stopped, or to provide a heat pump type air conditioner which does not require an external save circuit. The purpose is to provide a machine.

[0008]

According to the first aspect of the present invention,
In a heat pump air conditioner equipped with a compressor, an outdoor heat exchanger, an outdoor expansion valve, an indoor expansion valve, an indoor heat exchanger, and a four-way valve, the four-way valve can be switched without operating differential pressure. Control means for completely closing the outdoor expansion valve and the indoor expansion valve and switching the four-way valve to equalize the low-pressure side and the high-pressure side when the operation is stopped. It is characterized by.

Generally, when the outdoor expansion valve and the indoor expansion valve are fully closed at the time of operation stop, heat exchange of either the outdoor heat exchanger or the indoor heat exchanger is performed according to the cooling operation or the heating operation. Liquid refrigerant is stored in the vessel.

However, if it takes time to equalize the pressure on the low pressure side and the high pressure side in the refrigerant circuit, the liquid refrigerant stored in the heat exchanger is transferred to the suction pipe of the compressor due to the differential pressure generated during the time. There is a risk of inflow.

In the present invention, since the four-way valve is switched to forcibly equalize the low pressure side and the high pressure side, equalization between the low pressure side and the high pressure side in the refrigerant circuit is instantaneously performed, and heat exchange is performed. The movement of the liquid refrigerant stored in the vessel is prevented. Therefore,
Since liquid back to the compressor is prevented, an accumulator is not required.

According to a second aspect of the present invention, there is provided a heat pump air conditioner including a compressor, an outdoor heat exchanger, an indoor heat exchanger, and a four-way valve, wherein the four-way valve is a valve even if no operating pressure difference occurs. It has a switchable configuration, and provided with control means for performing control of switching the four-way valve during operation to return a part of the refrigerant discharged from the compressor to a suction pipe of the compressor.
It is characterized by the following.

In the present invention, during operation, control is performed to switch a four-way valve to return a part of the refrigerant discharged from the compressor to the suction pipe of the compressor, so that an external save circuit is not used. It becomes possible to control the capacity of the outdoor unit.

According to a third aspect of the present invention, there is provided the first or second aspect.
The described one is characterized in that a non-azeotropic mixed refrigerant composed of a high-boiling refrigerant and a low-boiling refrigerant is used.

[0015]

An embodiment of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a circuit diagram of a heat pump type air conditioner according to an embodiment of the present invention. The air conditioner according to this embodiment uses a non-azeotropic mixed refrigerant including a high-boiling refrigerant and a low-boiling refrigerant as the refrigerant circulating in the refrigerant circuit. As this non-azeotropic mixed refrigerant, for example, R134a
(Chemical formula; CH2FCF3), R125 (Chemical formula; C2
A mixed refrigerant of HF5) and R32 (chemical formula: CH2 F2) is used.

In general, R134a has a boiling point of -26.
° C, the boiling point of R125 is -48 ° C, and the boiling point of R32 is -52 ° C.

The refrigerant circuit shown in FIG. 1 includes a compressor 3, an indoor heat exchanger 5, an indoor expansion valve 7, a receiver tank 17, an outdoor expansion valve 10, an outdoor heat exchanger 9, and a four-way valve as a flow path switching valve. 11 are arranged in this order.

In this embodiment, an accumulator to be connected to the suction pipe 3A of the compressor 3 is generally omitted.

In this embodiment, the four-way valve 11 is used.
However, it has a configuration in which the valve can be switched without operating pressure difference. In general, the four-way valve cannot be switched without operating differential pressure in the refrigerant circuit. However, the four-way valve 11 can be switched without operating differential pressure. Moreover, it can be stopped at an intermediate position.

For example, a four-way valve for switching a flow path by a gear driving method disclosed in Japanese Patent Application Laid-Open No. 12-28232 is suitable, but is not limited thereto.
Those using various driving methods can be adopted.

When the operation of the air conditioner is stopped,
A control means 57 is provided for completely closing the outdoor expansion valve 10 and the indoor expansion valve 7 and inverting the four-way valve 11 to equalize the pressure on the high pressure side and the low pressure side.

The outdoor heat exchanger 9 functions as a condenser during cooling and as an evaporator during heating, and the indoor heat exchanger 5 functions as an evaporator during cooling and as a condenser during heating. .

The four-way valve 11 is positioned so as to allow the refrigerant to flow during the cooling operation as indicated by the broken line, and is positioned as indicated by the solid line during the heating operation. By switching the four-way valve in this manner, the refrigerant flow path for cooling and heating is switched.

Next, the operation of the above embodiment will be described.

During the heating operation, as shown by the solid arrows in FIG. 1, the compressor 3, the indoor heat exchanger 5, the indoor expansion valve 7, the receiver tank 17, the outdoor expansion valve 10, the outdoor heat exchanger 9,
The refrigerant is circulated in the order of the four-way valve 11.

The refrigerant introduced from the outdoor expansion valve 10 into the outdoor heat exchanger 9 is vaporized and pumps heat from the outside air because the outdoor heat exchanger 9 acts as an evaporator.

In the present embodiment, the suction pipe 3A of the compressor 3
In addition, since no accumulator for storing the liquid refrigerant is provided, the refrigerant to the compressor 3 must be almost completely vaporized before being sent.

Therefore, during the heating operation, the outdoor expansion valve 10
, The amount of refrigerant flowing into the outdoor heat exchanger 9 is controlled. This control is controlled by the control means 57. Thereby, the refrigerant is almost completely vaporized in the outdoor heat exchanger 9 and sent to the compressor 3, so that liquid back is prevented even without the accumulator.

On the other hand, during the cooling operation, as indicated by the dotted arrows in FIG. 1, the compressor 3, the outdoor heat exchanger 9, the outdoor expansion valve 10, the receiver tank 17, the indoor expansion valve 7, the indoor heat exchanger 5, The refrigerant is circulated in the order of the four-way valve 11.

The refrigerant introduced into the indoor heat exchanger 5 from the indoor expansion valve 7 is vaporized and pumps heat from the outside air because the indoor heat exchanger 5 acts as an evaporator.

In this case, the opening degree of the indoor expansion valve 7 is reduced, and the amount of refrigerant flowing into the indoor heat exchanger 5 is controlled. This control is controlled by the control means 57. Thereby, the refrigerant is almost completely vaporized in the indoor heat exchanger 5 and sent to the compressor 3, so that liquid back is prevented even without an accumulator.

In the present embodiment, the following control prevents liquid back when the operation is stopped without an accumulator.

That is, when the operation is stopped during the cooling operation, the control means 57 first controls the outdoor expansion valve 1.
0 and the indoor expansion valve 7 are fully closed. Thus, the liquid refrigerant is sealed in the interior of the indoor heat exchanger 5 and the like.

However, if the state is left as it is, immediately after the operation is stopped, while the high-pressure side and the low-pressure side in the refrigerant circuit are almost equalized, suction is performed by the low pressure in the suction pipe 3A of the compressor 3. As a result, the liquid refrigerant to be confined inside the indoor heat exchanger 5 moves to the compressor 3 side. If this situation occurs, liquid back to the compressor 3 cannot be prevented unless there is an accumulator in the suction pipe 3A of the compressor 3.

In this embodiment, in order to avoid this situation, immediately after the operation is stopped, the control means 57 controls the four-way valve 11.
Is switched and inverted.

Then, the discharge pipe 3B and the suction pipe 3 of the compressor 3
A is equalized, so that the liquid refrigerant in the indoor heat exchanger 5 does not move to the compressor 3 side and is directly contained in the indoor heat exchanger 5, so that there is no accumulator. However, liquid back to the compressor 3 is prevented.

If the operation is stopped during the heating operation, the outdoor expansion valve 10 and the indoor expansion valve 7 are fully closed by the control means 57. As a result, the liquid refrigerant is sealed inside the outdoor heat exchanger 9 or the like.

Immediately after the operation is stopped, the four-way valve 11 is switched by the control means 57 to be inverted. Then
The pressure between the discharge pipe 3B and the suction pipe 3A of the compressor 3 is equalized,
According to this, the liquid refrigerant in the outdoor heat exchanger 9 is supplied to the compressor 3
Since the liquid does not move to the side and is sealed in the outdoor heat exchanger 9 as it is, even if there is no accumulator, liquid back to the compressor 3 is prevented.

In this embodiment, since an accumulator is not required, the cost can be reduced and the size of the outdoor unit can be reduced.

Next, another embodiment will be described.

In this embodiment, since the four-way valve 11 has a configuration in which the valve can be switched without operating pressure difference, the four-way valve 11 can be turned over an arbitrary angle during the operation of the air conditioner. A control means 57 capable of switching is provided. If the switching angle is appropriately set, a part of the refrigerant discharged from the compressor 3 is directly returned to the suction pipe 3A according to the switching angle regardless of the cooling operation or the heating operation. Without using an external save circuit,
The capacity of the compressor 3 can be adjusted. The conventional external save circuit (not shown) is a circuit that connects a discharge pipe and a suction pipe of a compressor, and includes an electromagnetic on-off valve, a capillary tube, a strainer, and the like in the middle.

Therefore, the present embodiment has effects such as cost reduction and downsizing as compared with the conventional one provided with the external save circuit.

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

[0045]

According to the present invention, it is possible to prevent liquid back to the compressor when the operation is stopped without an accumulator. Further, the capacity of the outdoor unit can be adjusted without using an external save circuit.

[Brief description of the drawings]

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

[Explanation of symbols]

 Reference Signs List 3 Compressor 3A Suction pipe 3B Discharge pipe 5 Indoor heat exchanger 9 Outdoor heat exchanger 11 Four-way valve 17 Receiver tank 57 Control means

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yasuo Tajima 1 Otsukicho, Ashikaga, Tochigi Prefecture Sanyo Electric Air Conditioning Co., Ltd. (72) Inventor Kiyoshi Tamura 1 Otsukicho, Ashikaga, Tochigi Prefecture Sanyo Electric Air Conditioning Co., Ltd. (72) Inventor Tamura Yoshiyoshi Hisashi 1 Otsukicho, Ashikaga City, Tochigi Prefecture Sanyo Electric Air Conditioning Co., Ltd. F term (reference) 3L092 AA07 BA26 DA10 FA22 FA26

Claims (3)

[Claims] 1. A heat pump air conditioner comprising a compressor, an outdoor heat exchanger, an outdoor expansion valve, an indoor expansion valve, an indoor heat exchanger, and a four-way valve, wherein the four-way valve does not generate an operating differential pressure. Control means for completely closing the outdoor expansion valve and the indoor expansion valve and switching the four-way valve to equalize the low-pressure side and the high-pressure side when the operation is stopped. A heat pump type air conditioner comprising: 2. A heat pump type air conditioner comprising a compressor, an outdoor heat exchanger, an indoor heat exchanger and a four-way valve, wherein the four-way valve has a structure capable of switching valves even when no operating pressure difference occurs. And a control means for switching the four-way valve during operation to return a part of the refrigerant discharged from the compressor to a suction pipe of the compressor. Harmony machine. 3. The heat pump type air conditioner according to claim 1, wherein a non-azeotropic refrigerant mixture comprising a high boiling point refrigerant and a low boiling point refrigerant is used.