JPH08210711A - Air conditioner - Google Patents

Abstract

PURPOSE: To provide an air conditioner which can prevent a particular refrigerant from separating from a mixed refrigerant circulating the inside a heat- exchanger and from leaking. CONSTITUTION: An air conditioner has a refrigerant circuit through which a mixed refrigerant flows. When the temperature of an outdoor heat-exchanger 5 reaches a specified temperature at which a particular refrigerant vaporizes and speparates from the mixed refrigerant, a control part 10 controls the operation of a compressor 3 so that the compressor 3 operates at the minimum frequency, and hence this prevents the particular refrigerant only from gasifying and separating from the mixed refrigerant.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a mixed refrigerant (refrigerants R32, R125 and R134a at 23: 25: 5 as refrigerants).
Non-azeotropic mixed refrigerant or refrigerant R3 mixed in a weight ratio of 2
2, an air conditioner equipped with a refrigerant circuit using a pseudo-azeotropic mixed refrigerant in which R125 is mixed in a weight ratio of 50:50, and a mixed refrigerant mixed in a weight ratio equivalent to these, etc. The stabilization of.

[0002]

2. Description of the Related Art Conventionally, as a refrigerant used in an air conditioner,
A single refrigerant such as R-22 was used. However, in recent years, for the purpose of preventing the destruction of the ozone layer and the like, as disclosed in Japanese Patent Laid-Open No. 54-2561, a problematic chlorine-containing refrigerant is not used and a problem-free refrigerant is mixed. It is known to use a mixed refrigerant that is capable of obtaining the same ability in total.

In an air conditioner using such a mixed refrigerant, it is necessary to constantly maintain a constant composition ratio in order to maintain stable performance and safety of the mixed refrigerant.

[0004]

Such mixed refrigerant (refrigerants R32, R125, and R134a are mixed at 23: 25: 5).
Non-azeotropic mixed refrigerant or refrigerant R3 mixed in a weight ratio of 2
2, a pseudo-azeotropic mixed refrigerant in which R125 is mixed in a weight ratio of 50:50, and a mixed refrigerant in which R125 is mixed in a weight ratio equal to these, etc.), the boiling point of each refrigerant is R134a is −26 degrees Celsius, R125 is -48 degrees Celsius and R32 is -52 degrees Celsius.

Therefore, if the temperature of the outside air or the temperature of the outdoor heat exchanger falls too much below a predetermined temperature such as -30 degrees Celsius in the mixed refrigerant, only the refrigerant R32 having a low boiling point becomes a gas. Since the refrigerant R32 has a flammable property by itself, there is a risk of application if the refrigerant R32 alone leaks from the refrigerant circuit.

Also, in the case of mixed refrigerants of other combinations, if only a specific refrigerant vaporizes due to the difference in evaporation temperature and leaks from the refrigerant circuit, the mixing ratio of the refrigerants circulating in the refrigerant circuit changes, and There was a problem that the characteristics could not be obtained.

Therefore, in order to solve the above problems, the present invention provides an air conditioner capable of preventing a specific refrigerant (for example, a combustible refrigerant) from separating and leaking from a mixed refrigerant circulating in a heat exchanger. It is an object.

[0008]

According to a first aspect of the present invention, there is provided a refrigerant circuit in which a compressor, a condenser, a pressure reducing device, an evaporator and the like are annularly connected by a refrigerant pipe, and a plurality of refrigerant circuits are provided in the refrigerant circuit. In an air conditioner capable of performing an air conditioning operation by circulating a mixed refrigerant mixed with a refrigerant, the temperature of the mixed refrigerant in the refrigerant circuit or the ambient temperature is a predetermined temperature at which a specific refrigerant in the mixed refrigerant is gasified. When the following is reached, the mixed refrigerant is agitated in the refrigerant circuit.

According to the first aspect of the present invention, when the temperature of the mixed refrigerant in the refrigerant circuit reaches a temperature at which a specific refrigerant becomes a single gas and separates, the mixed refrigerant is agitated in the refrigerant circuit and specified. Only the refrigerant is prevented from becoming a gas and separated, and the temperature of the refrigerant is raised by stirring the refrigerant.

[0010]

DETAILED DESCRIPTION OF THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings.

As shown in FIG. 1, the air conditioner according to this embodiment is a separation type air conditioner having an outdoor heat exchanger 9 and an indoor heat exchanger 5, and the refrigerant circuit 1 of the air conditioner is ,
The outdoor heat exchanger 9, the four-way valve 11 as a flow path switching valve,
The compressor 3, the accumulator 13, the indoor heat exchanger 5, and the pressure reducer 7 are connected in this order by a refrigerant pipe. The outdoor heat exchanger 9 includes a fan 9a, and the indoor heat exchanger 5 includes a fan 5a to exchange heat between the outdoor air or the indoor air and the refrigerant.

The compressor 3 is electrically connected to the controller 40 and is driven in response to a control signal from the controller 40. As the compressor 3, either a rated one or an inverter may be used.

A bypass circuit 30 for the defrosting mode is provided between the high pressure side of the compressor 3 and the outdoor heat exchanger 9. The bypass circuit 30 is provided with a valve 32, which is controlled to open and close by a control signal from the control unit 40. The outdoor heat exchanger 9 is provided with a temperature sensor 50 that detects the outside air temperature. The temperature sensor 50 outputs the temperature detection signal S2 to the control unit 40.

As the refrigerant circulating in the refrigerant circuit of the air conditioner, for example, R134a is 52 wt% and R125 is 2%.
A mixed refrigerant in which 5 wt% and R32 are mixed at 23 wt% can be used. In general, the boiling point of R134a is-
The boiling point of 26 degrees and R125 is -48 degrees Celsius, and the boiling point of R32 is -52 degrees Celsius. In the mixed refrigerant having such a composition, only the low-refrigerant R32 having a boiling point is vaporized below -30 degrees Celsius, and R125 is 50 wt% and R32 is 50 wt%.
Similarly, even with the mixed refrigerant mixed in%, only R32 vaporizes.

Generally, the refrigerant R32 is a flammable refrigerant by itself, but becomes refractory when mixed with another refrigerant. For example, in the three-type mixed refrigerant having the above composition ratio,
Generally, at the time of evaporation, R32 and R125 having a low boiling point tend to evaporate first, and the three-type mixed refrigerant has R134a and R125 when the predetermined temperature becomes, for example, about -30 degrees or less.
Is separated as a liquid refrigerant, and only R32 is separated as a gaseous refrigerant.

Therefore, in such a mixed refrigerant, it is necessary to prevent only the flammable refrigerant from becoming a gas and separating.

Next, the operation of this embodiment will be described.

[Cooling Operation] In the cooling operation, in the refrigerant circuit of the air conditioner shown in FIG. 1, the indoor heat exchanger 5 acts as an evaporator, and the four-way valve 11 in FIG. 1 is positioned as shown by a broken line. Then, the refrigerant is circulated from the compressor 3 in the order of the four-way valve 11, the outdoor heat exchanger 9, the decompressor 7, the indoor heat exchanger 5, the four-way valve 11, the accumulator 13, and the compressor 3, as indicated by the dashed arrow. It In this case, the valve 32 of the bypass circuit 30 is closed.

[During Heating Operation] During heating operation, in the refrigerant circuit 1 of the air conditioner shown in FIG. 1, the outdoor heat exchanger 9 is used.
Acts as an evaporator, the four-way valve 11 is located as shown by the solid line, and the refrigerant is drawn from the compressor 3 as shown by the solid line arrow.
The indoor heat exchanger 5, the pressure reducing device 7, the outdoor heat exchanger 9, the four-way valve 11, the accumulator 13, and the compressor 3 are circulated in this order. In this case, the valve 32 of the bypass circuit 30 is closed.

On the other hand, the temperature sensor 50 is -10 degrees to -20 degrees.
When the temperature of the temperature is detected, the controller 40 drives the compressor 3 by giving the drive signal S1 to the compressor 3 in order to raise the temperature of the mixed refrigerant in the medium circuit. Moreover, in this embodiment, the compressor 3 is operated in the so-called defrosting mode, but the compressor 3 is slowly operated at the lowest frequency to stir the mixed refrigerant in the refrigerant circuit.
That is, the control unit 40 detects that the temperature sensor 50 is -10 degrees to -2 degrees.
When receiving the detection signal of 0 degree, the valve 3 of the bypass circuit 30
2 to open the valve 32 to open the compressor 3
Therefore, the hot refrigerant can be directly put into the outdoor heat exchanger 9 without passing through the four-way valve 11, the indoor heat exchanger 5, and the pressure reducing device 7.

The drive frequency of the compressor is preferably about the lowest frequency during normal operation, for example, about 10 Hz in this embodiment.

In this defrosting mode, when the valve 32 is opened, a reverse cycle occurs, and the hot refrigerant from the compressor 3 is directly introduced into the refrigerant pipe 19 of the outdoor heat exchanger 9, so that the outdoor heat exchanger 9 The refrigerant temperature is prevented from rising and falling below -30 degrees.

As described above, the reason why the compressor is driven within the temperature range of −10 ° C. to −20 ° C. detected by the temperature sensor 50 is that the temperature sensor 50 causes the temperature of the outdoor heat exchanger 9 to be −30 ° C. or lower. Already detected, R134a and R125 have already been detected.
Since R32 may be separated as a liquid refrigerant as a flammable gaseous refrigerant, preventive control is performed before such separation occurs.

The detection temperature for driving the compressor 3 may be a temperature that can prevent the flammable refrigerant from separating from the mixed refrigerant, and it depends on the kind of the refrigerant, but it is 10 to 20 degrees from the separation temperature. It is preferable to drive the compressor when only a high temperature is detected.

When the temperature detector 50 detects -10 degrees, the controller 40 issues a signal to stop the driving of the compressor 3 and simultaneously closes the valve 32. As a result, the defrosting operation ends.

By the way, the present invention can be variously modified without departing from the spirit of the present invention. For example,
In the embodiment described above, the mixed refrigerant is described as a three-type mixed refrigerant containing a flammable refrigerant, but the present invention is not limited to this, and a similar effect can be obtained with a two-type mixed refrigerant containing a flammable refrigerant. it can. Also, when a mixed refrigerant in which refrigerants with different boiling temperatures are mixed is used, the refrigerant mixing ratio in the refrigerant circuit changes due to the leakage of the refrigerant, and the initial setting capacity cannot be obtained. Can be suppressed.

When the defrosting operation is performed, the same effect can be obtained even in the normal defrosting operation by switching the four-way valve 11 without using the bypass circuit 30.

Further, the control unit 40 may detect not only the temperature detected by the outdoor heat exchanger but also the outside air temperature and drive the compressor 3 based on this.

[0029]

As described above, in the invention described in claim 1, when the outdoor heat exchanger reaches the temperature at which only the refrigerant having a low boiling point is vaporized and separated from the mixed refrigerant, the compressor is rotated at the lowest frequency. . This can prevent the temperature of the outdoor heat exchanger from falling below a predetermined temperature at which the specific refrigerant is separated, and thereby prevent the specific refrigerant from leaking.

[0030]

[Brief description of drawings]

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

[Explanation of symbols]

 3 Compressor 19 Outdoor heat exchanger 30 Bypass circuit S1 Control signal

Claims (1)

[Claims] 1. A refrigerant circuit in which a compressor, a condenser, a pressure reducing device, an evaporator, and the like are annularly connected by a refrigerant pipe, and a mixed refrigerant in which a plurality of refrigerants are mixed is circulated in the refrigerant circuit to perform an air conditioning operation. In the air conditioner made possible, when the temperature or the ambient temperature of the mixed refrigerant in the refrigerant circuit reaches a predetermined temperature or less at which a specific refrigerant in the mixed refrigerant is gasified,
An air conditioner comprising a configuration for stirring a mixed refrigerant in the refrigerant circuit.