JP2001355933A - Heat pump type air conditioner and its operating method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat pump type air conditioner capable of preventing the occurrence of liquid back during a stop of operation of an air conditioner. 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, and an indoor heat-exchanger 5. During starting, the outdoor expansion valve 10 or the indoor expansion valve 7 is brought into a state to be rather closed, and a control means 57 is provided to perform control of opening of an initial valve to increase a valve opening with a lapse of a time.

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 type, when the air conditioner is started, the initial step of the expansion valve is set to be constant, and the initial valve opening is controlled to be constant.

[0004]

However, if the initial valve opening is controlled to be constant, for example, when the air-conditioning load is large, the shortage of the refrigerant flowing into the heat exchanger due to the relative insufficient opening of the expansion valve. When the air-conditioning load is small, a large amount of refrigerant flows into the heat exchanger due to the relative opening of the expansion valve. There were problems such as occurrence of liquid back.

On the other hand, in recent years, a non-azeotropic mixed refrigerant composed of a high-boiling refrigerant and a low-boiling refrigerant may be used as a refrigerant. In this case, when this enters the accumulator, there is a problem that the low-boiling refrigerant is vaporized and sucked into the compressor, and a large amount of the high-boiling refrigerant 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, there has been proposed a technique 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.

However, when the accumulator is not provided, if the initial valve opening is controlled to be constant at the time of start-up as described above, for example, when the air-conditioning load is small, the relative expansion of the expansion valve causes the thermal expansion. There is a problem that a large amount of refrigerant flows into the exchanger and liquid back to the compressor occurs.

Accordingly, the present invention has been made to solve the above-mentioned problem, and it is an object of the present invention to provide a heat pump type air conditioner capable of preventing liquid back when the operation of the air conditioner is stopped. The purpose is.

[0009]

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, and an indoor heat exchanger,
At the time of activation, the outdoor expansion valve or the indoor expansion valve is set in a state of being closed slightly, and control means for performing initial valve opening control for opening the valve opening over time is provided.

According to a second aspect of the present invention, there is provided 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. Close the indoor expansion valve,
It is characterized by comprising control means for performing initial valve opening control to open the valve at a constant rate over time.

[0011] The invention according to claim 3 is the invention according to claim 1 or 2.
In the above description, a target valve opening of the initial valve opening control is determined in consideration of an air conditioning load.

The invention according to claim 4 is the first or second invention.
In the above description, a target valve opening of the initial valve opening control is determined in consideration of a temperature condition on the heat exchanger side acting as an evaporator.

[0013] The invention according to claim 5 is the invention according to claims 1 to 4.
Wherein the control time of the initial valve opening degree control is changed and controlled in accordance with a high-pressure container type compressor and a low-pressure container type compressor.

The invention according to claim 6 is the first to fifth aspects.
In any one of the above, the control time of the initial valve opening control, during the cooling operation, corresponding to the heating operation,
Change control is performed.

The invention according to claim 7 is the first to sixth aspects of the present invention.
Wherein the refrigerant of the air conditioner is a non-azeotropic mixed refrigerant composed of a high-boiling refrigerant and a low-boiling refrigerant.

The invention according to claim 8 is a method of operating 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. Alternatively, control means is provided for performing initial valve opening control for opening the valve opening over time with the indoor expansion valve being in a slightly closed state.

[0017]

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, the boiling point of R134a is -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.

A bypass pipe 51 is connected between the discharge pipe 3B of the compressor 3 and the suction pipe 3A.
1, a capillary tube 53 and an on-off valve 55 are connected in series. These constitute bypass means.

When the operation of the air conditioner is stopped,
Control means 57 is provided for fully closing the outdoor expansion valve 10 and the indoor expansion valve 7 and fully opening the on-off valve 55 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 flow the refrigerant as indicated by a broken line during the cooling operation, 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 to the outdoor heat exchanger 9 is vaporized and pumps heat from outside air because the outdoor heat exchanger 9 acts as an evaporator.

In this 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 from the indoor expansion valve 7 into the indoor heat exchanger 5 is vaporized and pumps heat from 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.

Further, the following control prevents the liquid back when the operation is stopped without the 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 this state is left as it is, immediately after the operation is stopped, until the high pressure side and the low pressure side in the refrigerant circuit are equalized, the pressure is sucked up by the low pressure in the suction pipe 3A of the compressor 3. Then, 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 order to avoid this situation, immediately after the operation is stopped, the control means 57 opens the on-off valve 55 fully.
Then, between the discharge pipe 3B and the suction pipe 3A of the compressor 3,
Forced equalization. According to this, since 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, even if there is no accumulator, the liquid refrigerant flows to the compressor 3. Liquid back 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 on-off valve 55 is fully opened by the control means 57. Then, the pressure between the discharge pipe 3B and the suction pipe 3A of the compressor 3 is forcibly 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.

According to this, since an accumulator is not required, the cost can be reduced and the size of the outdoor unit can be reduced. Further, the bypass means includes an on-off valve 5.
5, the resistance of the capillary tube 53 is set appropriately, and by opening the on-off valve 55 during the operation of the air conditioner, the flow of the refrigerant discharged from the compressor 3 is reduced. Part of the suction pipe 3A
Therefore, effects such as the ability to adjust the capacity of the compressor 3 can be obtained.

The present embodiment is characterized in the control at the time of starting the air conditioner.

That is, at the time of startup, the control means 57
2, the initial valve opening control of the expansion valve is performed as shown in FIG. The control time T of the initial valve opening control is, for example, about 3 minutes, and thereafter, the normal control of the expansion valve is performed.

During the cooling operation, the indoor expansion valve 7 is controlled in FIG. If the control at the time of starting the indoor expansion valve 7 is not properly executed, a shortage of refrigerant in the indoor heat exchanger 5 and a liquid back to the compressor 3 occur.

During the heating operation, the object to be controlled is the outdoor expansion valve 9, but the operation is the same, and the description is omitted.

In the present embodiment, at the time of startup, as shown in FIG. 2, the initial valve opening control for the indoor expansion valve 7 is executed.

In this initial valve opening control, the valve opening of the indoor expansion valve 7 is started from 100 steps. Here, the expansion valve 7 is opened and closed by a stepping motor (not shown), and 100 steps are almost fully closed. Thereafter, as the time elapses, the valve opening is opened at a fixed rate, and reaches 180 steps of the target valve opening A in the present control. Full opening is 480 steps.

According to this, starting from 100 steps of substantially full closing, the valve opening is opened to the target valve opening A at a fixed rate with the passage of time, so that even if there is no accumulator, Liquid back during startup is prevented.

The target valve opening A is determined in consideration of the air conditioning load.

In particular, it is desirable to determine in consideration of the temperature condition on the side of the heat exchanger that operates as an evaporator, which has a large influence. That is, in the cooling operation, for example, the suction temperature Tb of the indoor unit is considered as the temperature condition on the indoor heat exchanger 5 side, and in the heating operation, the outdoor air temperature OA is set as the temperature condition on the outdoor heat exchanger 9 side. Decide in consideration. In addition, the flow characteristic (flow rate change characteristic) of the expansion valve is quadratic. Therefore, the target valve opening (step) A is set based on the following equation.

During cooling operation Step A = a × (Tb + b) + c (1) During heating operation Step A = a ′ × (OA + b ′) + c ′ (2) a, a ′, b, b ′, c, c ′ = constant In this embodiment, the above-described target valve opening A is changed according to the air conditioning load. Therefore, appropriate initial valve opening control is performed according to the air-conditioning load, so that even when there is no accumulator, liquid back at startup is prevented, and the time required for stable operation after startup is reduced. . Further, the oil behavior is stabilized.

Next, another embodiment will be described.

In this embodiment, the control time T (FIG. 2) of the initial valve opening control is set to a high-pressure container type compressor (for example, a rotary compressor or the like) or a low-pressure container type compressor (for example, a scroll compressor). , Etc.). For example,
The control time T is set to be long because the discharge temperature does not easily rise in the high-pressure container type compressor, and the control time T is set short in the low-pressure container type compressor because the discharge temperature rises quickly. Further, the above control time T is set at the time of cooling operation,
Change control may be performed in response to the heating operation. For example,
Set short during cooling operation and long during heating operation.

According to this, it is possible to perform the optimal superheat operation start control, to prevent the liquid back at the start even in the absence of the accumulator, and to shorten the time until the stable operation after the start. .

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

[0055]

According to the present invention, it is possible to prevent liquid back to the compressor when the operation is stopped without an accumulator. This has the effect of shortening the time from the start of the air conditioner to the transition to stable operation, for example.

[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.

FIG. 2 is a control time chart of an expansion valve.

[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 DA06 EA18 FA26

Claims (8)

[Claims] 1. A heat pump air conditioner including a compressor, an outdoor heat exchanger, an outdoor expansion valve, an indoor expansion valve, and an indoor heat exchanger, wherein at start-up, the outdoor expansion valve or the indoor expansion valve is closed. A heat pump type air conditioner comprising a control means for performing an initial valve opening control for opening the valve opening as time elapses in the state described above. 2. A heat pump type air conditioner comprising a compressor, an outdoor heat exchanger, an outdoor expansion valve, an indoor expansion valve, and an indoor heat exchanger, wherein at start-up, the outdoor expansion valve or the indoor expansion valve is closed. A heat pump type air conditioner comprising control means for performing an initial valve opening control for opening the valve opening at a fixed rate with time from the state of (1). 3. The heat pump type air conditioner according to claim 1, wherein the target valve opening of the initial valve opening control is determined in consideration of an air conditioning load. 4. The heat pump according to claim 1, wherein a target valve opening of the initial valve opening control is determined in consideration of a temperature condition on a side of the heat exchanger acting as an evaporator. Type air conditioner. 5. The control method according to claim 1, wherein the control time of the initial valve opening control is changed corresponding to a high-pressure container type compressor and a low-pressure container type compressor. 2. The heat pump type air conditioner according to claim 1. 6. The heat pump air according to claim 1, wherein the control time of the initial valve opening degree control is changed in accordance with a cooling operation and a heating operation. Harmony machine. 7. The heat pump type air conditioner according to claim 1, wherein the refrigerant of the air conditioner is a non-azeotropic mixed refrigerant composed of a high-boiling refrigerant and a low-boiling refrigerant. . 8. A method for operating 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, wherein the outdoor expansion valve or the indoor expansion valve is activated at the time of startup. A method of operating the heat pump type air conditioner, characterized by comprising a control means for performing initial valve opening control for opening the valve opening as time elapses by closing the valve slightly.