JPH02247467A - Air conditioner - Google Patents

Abstract

PURPOSE:To prevent cold air from blowing into a room at a defrosting operation time during a heating operation, and also to prevent liquid refrigerant from being returned to a compressor by changing over a three-way change-over valve to carry out a defrosting operation while a four-way change-over valve is kept in the state of the heating operation. CONSTITUTION:During a cooling operation, refrigerant is decompressed by a first decompressor 4a in a first throttle device 4 and converted into liquid refrigerant under a low temperature and a low pressure. On the other hand, a portion of gas refrigerant under a high temperature and a high pressure, which has been discharged from a compressor 1, passes through a third bypass circulating path 10 and exchange heat with low-pressure refrigerant, which is sucked into the compressor 1, at a suction heat exchanger 11 to heat and completely gasifies the refrigerant to be sucked into the compressor 1, while the high-temperature and high-pressure refrigerant itself is condensed to be liquefied, and is decompressed by an auxiliary capillary tube 12 to be converted into liquid refrigerant under a low temperature and a low pressure. The resultant refrigerant flows into a pipeline arranged between the first throttle device 4 and a second throttle device 5 and passes through a second bypass circulating path 5c in the second throttle device 5 to enter an indoor side heat exchanger 6 and then exchanges heat with indoor air blown from an indoor side blower 8 to cool the indoor air. According to this method, the liquid refrigerant is gasified and passes through a four-way change-over valve 2 and an accumulator 7 to return to the compressor 1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improvement in an air conditioner that performs heating and cooling operations using a refrigeration cycle circuit.

[Conventional technology]

Conventionally, this type of air conditioner has been configured as schematically shown in FIG. To explain this simply, in the figure (υ
is a compressor, (2) is a four-way switching valve, (3) is an outdoor heat exchanger, 141.151 is a first and second throttling device that functions as an expansion mechanism during cooling operation and heating operation, respectively;
(6) is the indoor heat exchanger, (7) is the accumulator,
A refrigeration cycle circuit is constructed by sequentially connecting these through refrigerant piping. In addition, 181. (9) is indoor side, outdoor side heat exchanger +61. Indoor and outdoor blowers that blow air respectively, (4a) and (4b
) is the first vacuum bag @(
capillary tube) and the first check valve provided in the circuit bypassing this, (5m), (5b) is the second pressure reducing device (capillary tube) constituting the second throttle device (5) and This is a second check valve provided in the circuit that bypasses this.

In an air conditioner with such a configuration, during cooling operation (the flow of the refrigerant is indicated by the thick solid line arrow in the figure), the high temperature and high pressure gas refrigerant discharged from the compressor (1) is
The gas refrigerant passes through the four-way switching valve 121, exchanges heat with outdoor air blown by the outdoor fan (9) in the outdoor heat exchanger (3), and is condensed and liquefied.

Then, it passes through the first check valve (4b) in the bypass circuit on the side of the first throttle device ff1t4+, and enters the second throttle device (
5), the refrigerant is introduced into the second pressure reducing device (5a), and the pressure is reduced, and the refrigerant becomes a low-temperature, low-pressure liquid refrigerant. This liquid refrigerant then enters the indoor heat exchanger (61) and enters the indoor blower (8).
In addition to exchanging heat with the indoor air blown by the refrigerant and cooling the indoor air, the liquid refrigerant is evaporated and gasified.
Compression via four-way switching valve (2) and accumulator (7) @
The refrigeration cycle during cooling is configured by returning to tlJ, and thereafter the refrigerant is sequentially liquefied through the above-mentioned refrigeration cycle path.
It is circulated while slowly evaporating.

On the other hand, during heating operation (the flow of refrigerant is shown by the thin solid line arrow in the figure), the high temperature and high pressure gas refrigerant discharged from the compression fitlJ is transferred to the four-way switching valve (which is switched to the heating side).
2), enters the indoor heat exchanger (6), heats the indoor air by exchanging heat with the indoor air blown by the indoor blower (8), and thereby condenses and liquefies the gas refrigerant. Then, this liquid refrigerant is passed through the second expansion device (5
) in the circuit that bypasses the first pressure reducing device (4) constituting the first throttling device (4).
&) and is depressurized, becoming a low-temperature, low-pressure liquid refrigerant. After that, the liquid refrigerant enters the outdoor heat exchanger (3), exchanges heat with the outdoor air blown by the outdoor fan (9), collects heat from the outdoor air, and cools the outdoor air. It evaporates and becomes gas, passes through the four-way switching valve (2) and the accumulator (7), and returns to the compressor 111, thereby forming a refrigeration cycle during heating.

Also, if you continue to use this type of heating operation,
For example, when the outdoor air temperature is low, the outdoor heat exchanger (3
1. Frost formation occurs. When such frost formation increases, the heat exchange efficiency deteriorates, and the amount of heat extracted from the outdoor air decreases, resulting in a significant decrease in the heating capacity of the air conditioner. Therefore, in such a case, it is necessary to perform defrosting.

During such defrost operation (the flow of refrigerant is indicated by the dashed arrow in the figure), the high temperature, high pressure gas refrigerant discharged from the compressor (υ) is transferred to the four-way switching valve that is switched from the heating side to the cooling side. (21, and enters the outdoor heat exchanger (31). At this point, the outdoor fan (9) is stopped. Then, the frost that has formed on the surface of this outdoor heat exchanger (31) is removed. The refrigerant is dissolved in the hot gas refrigerant, and this refrigerant is condensed and liquefied to pass through the first check valve (4b) which bypasses the first throttling device (4), and passes through the second check valve (4b) which constitutes the second throttling device (5). It is depressurized by a pressure reducing device (5 m) and becomes a low temperature, low pressure liquid refrigerant.
A refrigeration cycle operation was performed in which the air enters the indoor heat exchanger (6), then returns to the compressor (υ) through the four-way switching valve (2) and the accumulator (7).

[Problem to be solved by the invention]

By the way, some problems occur when a low temperature, low pressure liquid refrigerant is introduced into the indoor heat exchanger (6) during the defrost operation during the above-mentioned heating operation.

That is, the indoor blower (8) disposed opposite to the indoor heat exchanger (6) normally performs a gentle breeze operation or is stopped during the defrost operation. For example, when operating in a breeze, the low-temperature, low-pressure liquid refrigerant and the indoor air exchange heat, cool the indoor air, and the liquid refrigerant evaporates into gas, causing the four-way switching valve (2) and the accumulator (7 ) through compression atυ
Return to Therefore, in such a case, cold air is blown toward the indoor side, causing a problem in that the air conditioner is significantly degraded.

Also, indoor ventilation 8! If +81 is stopped,
Heat cannot be collected from the low-temperature, low-pressure liquid refrigerant, and the refrigerant enters the accumulator (7) as a liquid and returns to the compressor ill, so the compressor (υ) compresses the liquid, sometimes causing compressor trouble.

Furthermore, according to the above-mentioned conventional device, since the high pressure is low especially during defrosting, the low pressure also decreases, making it impossible to fully utilize the capacity of the compressor (1), and the defrosting time takes a long time. Ta. Furthermore, since the four-way switching valve (2) is switched to the cooling side during the heating operation to perform the defrost operation, there is also a problem that heat loss occurs during the switching.

The present invention has been made in view of the above-mentioned circumstances, and it prevents cold air from being blown into the room during defrost operation during heating operation, and also allows defrost operation to be performed with the four-way switching valve set to the heating side. The purpose of the present invention is to obtain an air conditioner that can increase the pressure, enhance the compression function, and prevent liquid from returning to the compressor.

[Means to solve the problem]

The air conditioner according to the present invention has first and second pressure reducing devices each having a check valve that bypasses the first pressure reducing device and the second pressure reducing device.
a bypass circuit and a piping connected from the discharge side piping of the compressor to the piping side between the first and second throttling devices via a three-way switching valve, and having an inner diameter smaller than the discharge side piping; A fourth bypass circuit having a first discharge pressure regulating valve that bypasses this piping is provided, and furthermore, a fourth bypass circuit is connected to the inlet piping side of the accumulator in a bypass manner, and a second discharge pressure regulating valve is connected to the inlet piping side of the accumulator. A fifth bypass circuit having a valve is provided.

[Effect]

According to the present invention, during defrost operation during heating operation, the blower to the indoor and outdoor heat exchangers is stopped while the four-way switching valve remains in the heating operation state.

In addition, by switching the three-way switching valve and opening both the fourth bypass circuit or the fourth and fifth bypass circuits to perform defrost operation, heat loss when switching the four-way switching valve as in the conventional method is prevented, and In addition to preventing cold air from blowing into the room, both the high and low pressures of this refrigeration cycle are
Since the compressor is operated under high pressure conditions, the capacity of the compressor is increased and liquid return phenomenon can be prevented.

〔Example〕

FIG. 1 shows an embodiment of an air conditioner according to the present invention, and in this figure, the same or corresponding parts as in FIG.

Now, according to the present invention, the compressor 113, the four-way switching valve +2
1. The outdoor heat exchanger (3), the first throttle device (4), the second throttle device (5), the indoor heat exchanger (6), and the accumulator (1) are connected in sequence with refrigerant piping. In an air conditioner equipped with a refrigerant circuit, the compressor (υ) is branched from the discharge side piping, and the accumulator (7) and the pressure ff
The first and second
A third bypass pipe σG is connected to the piping side between 41 and 151 in a bypass manner, and a check valve (4b) that bypasses the first pressure reducing device (4 m) is provided. The first bypass circuit (4c) and the second pressure reducing device (5a
) is provided, and a second bypass circuit (5C) equipped with a check valve (5b) that bypasses the compression 831 (υ) is provided, and the first and a second throttle device (connected to the piping side between 41 and 151 in a bypass manner and having an inner diameter smaller than the inner diameter of the discharge side piping (1b)) and a first throttle device that bypasses this piping (g). A fourth bypass circuit α4 having a discharge pressure regulating valve α and a fourth bypass circuit α4 is bypassed and connected to the inlet piping side of the accumulator (7), and has a second discharge pressure regulating valve (to). A fifth bypass circuit is provided.

In such a configuration, during defrost operation, the four-way switching valve (2) is kept in the heating operation state, and the blower [61, +3 ζ] blows air from the indoor and outdoor heat exchangers.
81, (stops 91 and switches the three-way switching valve 0 to the fourth and fifth bypass circuits αI.

(Foundation) is opened to allow defrost operation.

In the air conditioner with the above configuration, during cooling operation C
The refrigerant flow is in the direction of the arrow indicated by the thick solid line in the figure).The high temperature and high pressure gas refrigerant discharged from the compressor (1) passes through the four-way switching valve (2) and is transferred to the outdoor side by the outdoor heat exchanger (3). While exchanging heat with the outdoor air blown by the blower (9), the gas refrigerant is condensed and liquefied.
The pressure is reduced by the first pressure reducing device (4&) in the expansion device (4), and the refrigerant becomes a low-temperature, low-pressure liquid refrigerant. On the other hand, a part of the high-temperature, high-pressure gas refrigerant discharged from the compressor (1) passes through the third bypass circuit αG to the suction heat exchanger (b).
The refrigerant exchanges heat with the low-pressure refrigerant sucked into the compressor (υ), heats the suction refrigerant, completely vaporizes it, condenses and liquefies itself, and is depressurized by the auxiliary capillary tube (2) to become a low-temperature, low-pressure liquid refrigerant. The first and second aperture devices (41, 1
51, passes through the second bypass circuit [5C] in the second throttle device (5), and connects to the indoor heat exchanger (5C).
6) and exchanges heat with the indoor air blown from the indoor air blower Fata+ to cool the indoor air, and the liquid refrigerant is thereby turned into vapor gas, passes through the four-way switching valve +2) and the accumulator (7), and is compressed 11 ( A refrigeration cycle circuit that returns to IJ is configured.

In addition, during heating operation (the flow of refrigerant is in the direction of the arrow indicated by the thin solid line in the figure), the high temperature and high pressure gas refrigerant discharged from the compressor 113 passes through the four-way switching valve +21 which is switched to the heating side, to the indoor side. The gas refrigerant enters the heat exchanger (6) and heats the indoor air by exchanging heat with the indoor air blown from the indoor 4!11 blower (81), and thereby condenses and liquefies the gas refrigerant. The pressure is reduced by the second pressure reducing device (5&) in (5), and it becomes a low temperature, low pressure liquid refrigerant.On the other hand, a part of the high temperature and high pressure gas refrigerant discharged from the compressor (1) is transferred to the third bypass circuit. It passes through αG and exchanges heat with the low-pressure refrigerant sucked into the compression all IIJ at the suction heat exchanger α℃, heating the suction refrigerant and completely vaporizing it.
It condenses and liquefies itself, is depressurized by the auxiliary capillary tube (2), becomes a low-temperature, low-pressure liquid refrigerant, merges into the piping side, and flows into the first restrictor W! ! (It passes through the first bypass circuit (46) at 41, enters the outdoor heat exchanger (31), exchanges heat with the outdoor air blown from the outdoor fan (9), collects heat from the outdoor air, and cools the outdoor air. At the same time,
As a result, the liquid refrigerant is evaporated and gasified, and the four-way switching valve (2)
A refrigeration cycle circuit is configured in which the refrigeration cycle passes through the accumulator (7) and returns to the compressor (1).

In addition, during such a heating operation, for example, when the outdoor air temperature is low and an M box is generated in the outdoor heat exchanger (3), the flow of the C refrigerant during the defrost operation, which is required, is indicated by the arrow indicated by the broken line in the figure. direction).

The high-temperature, high-pressure gas refrigerant discharged from the compression s(1) is transferred to the three-way switching valve (to) which is switched to the defrost side.
It flows into the piping side through the piping (G) of the fourth bypass circuit α4, which is connected to the piping side between the first and second throttle devices @ (41 and 151).

On the other hand, a part of the high-temperature, high-pressure gas refrigerant discharged from the compressor (1) passes through the third bypass circuit αO and is passed through the suction heat exchanger (b) to the compressor (low-pressure It exchanges heat with the refrigerant, heats the suction refrigerant and completely vaporizes it, and condenses and liquefies itself and reduces the pressure by the auxiliary capillary tube (2) to become a low-temperature, low-pressure liquid refrigerant. It is mixed with high-temperature, high-pressure gas refrigerant that has passed through the

These combined gas refrigerants then pass through the first bypass circuit (46) in the first expansion device (4) and enter the outdoor heat exchanger (31. At this time, the outdoor side blower (9)
) has been stopped. Then, the high-temperature gas refrigerant melts the frost that has formed on the surface of the outdoor heat exchanger (3), and this refrigerant condenses and liquefies and passes through the four-way switching valve (2) to the accumulator (7). It will be returned to the compressor (υ).

Therefore, during such defrosting, the four-way switching valve (2) is not switched from the heating side to the cooling side.
Defrost operation can be entered, so there is no heat loss due to switching. Furthermore, since the low-temperature liquid refrigerant does not pass through the indoor heat exchanger (6), the conventional problem of cold air being blown indoors is also solved.

Further, piping (
(to) is made smaller than the discharge side pipe (lb), pressure loss occurs, the pressure on the high pressure side of the compressor tlJ increases, and the input increases, so the capacity of compression 5 (1) increases. , it becomes possible to shorten the defrost time.

In addition, the defrost end signal detects the temperature on the outlet side of the outdoor heat exchanger (31) during defrost using a detection device such as a thermistor, but because the pressure on the high pressure side is increased, a sudden high pressure signal occurs just before the end of defrost. Due to the increase in side pressure, the outdoor heat exchanger (3) may be abnormally stopped due to high pressure cut before the outlet side temperature reaches the end temperature.At this time, the diameter of the discharge side pipe in the middle of the fourth bypass circuit α4 may be Thin piping (to)
The first discharge pressure regulating valve α0, which bypasses the discharge pressure, opens and maintains the high pressure side pressure constant.

However, if the high pressure increases even more rapidly, the second discharge pressure regulating valve (to), which has a slightly higher set value than the first discharge pressure regulating valve 06, is opened and the high temperature/high pressure gas refrigerant is transferred to the low pressure side. It is possible to maintain a constant high pressure by bypassing and prevent abnormal stoppages due to high pressure cuts.

Further, since the difference between high and low pressures is larger in the fifth bypass circuit (to) than in the fourth bypass circuit α4, the gas refrigerant can be bypassed smoothly, which is highly effective in keeping the high pressure constant.

In addition, since the suction heat exchanger I is configured to exchange heat with the suction side piping (1a) to the compressor (1) using the high temperature and high pressure gas refrigerant discharged from the compressor (13), compression @ (1 ), it is possible to prevent the phenomenon of liquid returning to the tank, and it is possible to prevent compressor troubles.

In addition, if the electric heater is installed facing the indoor heat exchanger (6) as shown in the figure, the refrigerant will not pass through the indoor heat exchanger (6) during defrost operation. , the indoor fan (8) can be operated, and the heating operation can be continued even during the defrosting operation. During such a defrost operation, a part of the high-temperature, high-pressure gas refrigerant passing through the fourth bypass circuit α4 is branched to the fifth bypass circuit αη, and the flow rate is controlled by the second discharge pressure regulating valve. The accumulator (7
), the low pressure increases while the high pressure is kept constant, increasing the capacity of the compressor (υ).
This has the advantage that the defrost time can be further shortened.

〔Effect of the invention〕

As explained above, according to the air conditioner according to the present invention, it is possible to perform defrost operation by switching the three-way switching valve while keeping the four-way switching valve in heating mode, which is different from the conventional four-way switching valve. It has various excellent effects, such as being able to prevent heat loss caused by switching, and eliminating the conventional problem of blowing cold air toward the indoor side. Furthermore, during defrost operation, the gas refrigerant on the discharge side from the compressor passes through a bypass circuit having a pipe with an inner diameter smaller than that on the discharge side, increasing the high pressure, thereby improving the compression function. This has the advantage of shortening the defrost time.

In addition, if the high pressure increases too much during defrost operation, the first discharge pressure regulating valve will maintain the high pressure constant, and if the high pressure increases further, the second discharge pressure regulating valve will control the discharge side gas. By bypassing the refrigerant to the low pressure side and controlling the high pressure to a constant level, it is possible to prevent abnormal shutdowns due to high pressure cuts.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of a refrigeration cycle circuit showing one embodiment of an air conditioner according to the present invention, and FIG. 2 is a schematic configuration diagram of a refrigeration cycle circuit showing a conventional example. In these figures, (υ is the compressor, (1m) is the suction side piping, (lb) is the discharge side piping, (2) is the four-way switching valve, (
3) is the outdoor heat exchanger, (41, (51 is the first and second throttle device, (4m), C3a1 is the first and second pressure reducing device, (4b), (5b) is the check valve , (4o
), (5a) are the first and second bypass circuits, (6
) is the indoor heat exchanger, (7) is the accumulator, 18
1. (91 is the indoor side and outdoor side blower, 0 is the three-way switching valve, α4 is the fourth bypass circuit, (to) is the thin tube, αQ
is the first discharge pressure regulating valve, or the fifth bypass circuit, (
) is the second discharge pressure regulating valve. Note that the same reference numerals in each figure indicate the same or equivalent parts.

Claims (1)

[Claims] A refrigerant circuit comprising a compressor, a four-way switching valve, an outdoor heat exchanger, a first expansion device, a second expansion device, an indoor heat exchanger, and an accumulator connected in sequence through refrigerant piping;
a first bypass circuit having a check valve that bypasses a first pressure reducing device constituting the throttling device; and a second bypass circuit having a check valve bypassing a second pressure reducing device constituting the second throttling device. A bypass circuit is provided, and the first and second
A fourth tube connected to the piping side between the throttle devices in a bypass manner and having an inner diameter smaller than the inner diameter of the discharge side piping, and a first discharge pressure regulating valve that bypasses this piping.
and a fifth bypass circuit connected from the fourth bypass circuit to the inlet piping side of the accumulator and having a second discharge pressure regulating valve. An air conditioner characterized in that the bypass circuit of No. 5 is configured to be open.