JPH07117323B2 - Air conditioner - Google Patents

Description

TECHNICAL FIELD The present invention relates to an improvement of an air conditioner that performs cooling / heating operation using a refrigeration cycle circuit.

[Conventional technology]

Conventionally, this type of air conditioner has a structure as schematically shown in FIG. To briefly explain this, in the figure, (1) is a compressor, (2) is a four-way switching valve, (3) is an outdoor heat exchanger, and (4) and (5) are respectively during cooling operation and heating operation. The first and second expansion devices functioning as expansion mechanisms, (6) is an indoor heat exchanger, and (7) is an accumulator, and a refrigeration cycle circuit is formed by sequentially connecting and connecting these with refrigerant pipes. . In addition, (8), (9)
Are indoor and outdoor blowers that blow air to the indoor heat exchangers (6) and (3), respectively, and (4a) and (4)
b) is a first pressure reducing device (capillary tube) constituting the first expansion device (4) and a first check valve provided in a circuit bypassing the first reducing device (5a), (5b). A second pressure reducing device (capillary tube) that constitutes the second expansion device (5) and a second check valve provided in a circuit that bypasses the second pressure reducing device (capillary tube).

In the air conditioner having such a configuration, during the cooling operation (the flow of the refrigerant is indicated by a thick solid arrow in the figure), the high-temperature and high-pressure gas refrigerant discharged from the compressor (1) is supplied to the four-way switching valve ( After passing through 2), the outdoor heat exchanger (3) exchanges heat with the outdoor air blown by the outdoor blower (9), and the gas refrigerant is condensed and liquefied. The first check valve (4b) in the bypass circuit on the side of the first expansion device (4)
And is introduced into the second pressure reducing device (5a) side of the second expansion device (5) to be reduced in pressure to become a low-temperature low-pressure liquid refrigerant. After that, the liquid refrigerant enters the indoor heat exchanger (6), exchanges heat with the indoor air blown by the indoor blower (8), cools the indoor air, and thereby the liquid refrigerant evaporates gas. A refrigeration cycle during cooling is configured by returning to the compressor (1) through the four-way switching valve (2) and the accumulator (7), and the refrigerant is liquefied and vaporized repeatedly in the refrigeration cycle path described above. Circulated.

On the other hand, during the heating operation (the flow of the refrigerant is indicated by a thin solid arrow in the figure), the high-temperature and high-pressure gas refrigerant discharged from the compressor (1) is switched to the heating side by the four-way switching valve (2).
And enters the indoor heat exchanger (6) to exchange heat with the indoor air blown by the indoor blower (8) to heat the indoor air, and thereby the gas refrigerant is condensed and liquefied. Then, this liquid refrigerant is used as the second expansion device (5).
Passing through the second check valve (5b) in the circuit for bypassing, and being led to the first pressure reducing device (4a) constituting the first expansion device (4) to be decompressed, and become a low-temperature low-pressure liquid refrigerant. Become. afterwards,
The liquid refrigerant enters the outdoor heat exchanger (3) and exchanges heat with the outdoor air blown by the outdoor blower (9) to collect heat from the outdoor air and cool the outdoor air. The gas is vaporized and returned to the compressor (1) through the four-way switching valve (2) and the accumulator (7), which constitutes a refrigeration cycle during heating.

In addition, if such heating operation is continued,
For example, when the outdoor air temperature is low, frost forms on the outdoor heat exchanger (3). When such frost formation increases, the heat exchange efficiency deteriorates and the amount of heat collected from the outdoor air decreases, so that the heating capacity of the air conditioner significantly decreases.
Therefore, in such cases, defrost
Is required to do.

During such a defrost operation (refrigerant flow is indicated by a dashed arrow in the figure), the high-temperature and high-pressure gas refrigerant discharged from the compressor (1) is switched from the heating side to the cooling side by four-way switching. Pass the valve (2) and enter the outdoor heat exchanger (3). Here, the outdoor blower (9) is stopped. Then, the frost formed on the surface of the outdoor heat exchanger (3) is melted by the high-temperature gas refrigerant, and the refrigerant is condensed and liquefied to form the first gas.
Of the low-temperature low-pressure liquid passing through the first check valve (4b) bypassing the expansion device (4) of FIG. 2 and reduced in pressure by the second pressure reducing device (5a) constituting the second expansion device (5). The refrigerant becomes a refrigerant, enters the indoor heat exchanger (6), and then passes through the four-way switching valve (2) and the accumulator (7) to return to the compressor (1), thereby performing a refrigeration cycle operation.

[Problems to be Solved by the Invention]

By the way, during the defrosting operation during the heating operation described above, when a low-temperature low-pressure liquid refrigerant is introduced into the indoor heat exchanger (6), some problems occur. That is, the indoor blower (8) arranged so as to face the indoor heat exchanger (6) is normally performing a slight wind operation or is stopped during the defrost operation. Then, for example, when the breeze operation is performed, the low-temperature low-pressure liquid refrigerant and room air are heat-exchanged, the room air is cooled, and the liquid refrigerant is vaporized into gas, and the four-way switching valve (2) and the accumulator ( Return to compressor (1) via 7). Therefore, in such a case, there is a problem that cold air is blown to the inside of the room and the air conditioning effect is significantly reduced.

Further, when the indoor blower (8) is stopped, the low-temperature low-pressure liquid refrigerant cannot collect heat, and the refrigerant enters the accumulator (7) as a liquid and returns to the compressor (1). 1) was liquid-compressed, which could cause compressor trouble.

Further, according to the above-mentioned conventional apparatus, since the high pressure is low especially at the time of defrosting, the low pressure also decreases, the capacity of the compressor (1) cannot be fully exerted, and the defrosting time takes a long time. I got it. In addition, since the four-way switching valve (2) is switched to the cooling side during the heating operation and the defrost operation is performed, there is a problem that heat loss occurs during the switching.

The present invention has been made in view of the above-mentioned circumstances, and prevents the blowing of cold air into the room during the defrosting operation during the heating operation, and performs the defrosting operation with the four-way switching valve left on the heating side. An air conditioner that can prevent the liquid from returning to the compressor by increasing the pressure to increase the compression function and also by performing heat exchange between the high temperature and high pressure gas refrigerant from the compressor and the suction side pipe. The purpose is to get.

[Means for Solving the Problems]

The air conditioner according to the present invention includes a compressor, a four-way switching valve that switches the flow of high-temperature and high-pressure refrigerant discharged from the compressor, an outdoor heat exchanger including an outdoor blower, and a refrigerant during heating. An air conditioner comprising a second expansion device for decompressing and an indoor heat exchanger equipped with an indoor blower, which is sequentially connected by a refrigerant pipe to form a refrigerant circuit,
A first bypass circuit for bypassing and connecting to the pipe connecting the outdoor heat exchanger and the second expansion device via a three-way switching valve connected between the refrigerant discharge pipe of the compressor and the four-way switching valve; A second bypass circuit, which is connected to the suction side pipe of the compressor by bypass from the first bypass circuit, and which has a discharge pressure adjusting valve and an auxiliary pressure reducing means, is provided, and the three-way switching valve is used during heating operation. The heating operation is performed by opening the four-way switching valve side, and during the defrost operation, the three-way switching valve is opened to the first bypass circuit side while the four-way switching valve is in the heating operation and the defrost operation is performed, and the pressure on the high pressure side of the compressor is increased. When the pressure reaches a predetermined high pressure value, the discharge pressure adjusting valve of the second bypass circuit is opened.

Further, the first bypass circuit has a pipe having an inner diameter smaller than that of the discharge side pipe of the compressor.

Further, the refrigerant circuit is provided with a first expansion device that reduces the pressure of the refrigerant during cooling, and the first expansion device and the second expansion device are:
While having a bypass circuit that bypasses each pressure reducing device, each of the bypass circuits is provided with a check valve that allows the flow of the refrigerant only to the outdoor side and the indoor side heat exchangers, and the refrigerant discharge of the compressor. A bypass circuit for bypassing and connecting between the pipe and the pipe connecting the first and second expansion devices is provided, and the bypass circuit performs heat exchange with the refrigerant suction pipe of the compressor in the middle of the pipeline. And a decompression device for decompressing the refrigerant.

[Action]

According to the present invention, during the defrost operation during the heating operation, the three-way switching valve is switched while the four-way switching valve is kept in the heating operation state, and the first bypass circuit or both the first and second bypass circuits are opened. And by defrosting,
It is possible to prevent heat loss when switching the conventional four-way switching valve.

Further, the first bypass circuit has a pipe having an inner diameter smaller than the inner diameter of the discharge side pipe of the compressor, pressure loss occurs, the high pressure side pressure of the compressor rises, and one input increases, Compressor capacity is increased and defrost time is reduced.

In addition, the suction heat exchange section heats the refrigerant drawn into the compressor to completely vaporize it.

〔Example〕

FIG. 1 shows an embodiment of an air conditioner according to the present invention, in which the same or corresponding parts as those in FIG. 2 described above are designated by the same reference numerals and the description thereof is omitted.

Now, according to the present invention, a compressor (1), a four-way switching valve (2), an outdoor heat exchanger (3), a first expansion device (4), a second expansion device (5), an indoor side. Heat exchanger (6)
In an air conditioner including a refrigerant circuit in which the accumulator (7) is sequentially connected by a refrigerant pipe, the accumulator (7) and the compressor (1) branched from the discharge side pipe (1b) of the compressor (1). The first and second throttle devices (4) are passed through a suction heat exchanger (11) configured to be capable of heat exchange with a suction side pipe (1a) connecting between the first side and the second side and a supplementary capillary tube (12). ), (5) is provided with a bypass pipe (10) connected by bypass on the pipe side,
And a check valve (4b) that bypasses the first pressure reducing device (4a)
Bypass circuit (4c) provided with a second decompression device (5a)
And a third bypass circuit (5c) provided with a check valve (5b) for bypassing the first side, and the first side via the three-way switching valve (13) from the discharge side pipe (1b) of the compressor (1). And a first bypass circuit having a pipe (15) having an inner diameter smaller than the inner diameter of the discharge side pipe (1b), which is connected by bypass to the pipe side between the second expansion devices (4) and (5). A second bypass circuit (14) provided with a discharge pressure control valve (16) connected by bypass from the upstream side to the inlet pipe side of the accumulator (7) and an auxiliary carrier tube (18) as auxiliary pressure reducing means (18). 17) is provided. In such a configuration, the blowers (8) and (9) for blowing air to the indoor and outdoor heat exchangers (6) and (3) while keeping the four-way switching valve (2) in the heating operation state during defrost operation. ) Is stopped and the three-way switching valve (13) is switched to open the first bypass circuit (14) so that the defrost operation can be performed.

In the air conditioner having the above-described configuration, during the cooling operation (the refrigerant flow is in the direction of the arrow indicated by the thick solid line in the figure), the high-temperature high-pressure gas refrigerant discharged from the compressor (1) is supplied to the four-way switching valve (2). Through the outdoor heat exchanger (3) to exchange heat with the outdoor air blown by the outdoor blower (9), whereby the gas refrigerant is condensed and liquefied. Then, the pressure is reduced by the first pressure reducing device (4a) in the first expansion device (4) to become 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) passes through the bypass circuit (10) and the low-pressure refrigerant and heat which are sucked into the compressor (1) by the suction heat exchanger (11). The refrigerant is exchanged, the suction refrigerant is heated to be completely vaporized, and the condensed refrigerant itself is condensed and liquefied, and the pressure is reduced by the auxiliary capillary tube (12) to become a low temperature and low pressure liquid refrigerant, and the first and second expansion devices (4 ),
Indoor air that joins the pipe between (5), passes through the bypass circuit (5c) in the second expansion device (5), enters the indoor heat exchanger (6), and is blown from the indoor blower (8). A refrigeration cycle circuit is constructed in which heat is exchanged with the room air to cool the indoor air, and thereby the liquid refrigerant is vaporized and gasified and returned to the compressor (1) through the four-way switching valve (2) and the accumulator (7).

Further, during the heating operation (the flow of the refrigerant is 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 (1) flows through the four-way switching valve (2) switched to the heating side. The air enters the indoor heat exchanger (6) and exchanges heat with the indoor air blown from the indoor blower (8) to heat the indoor air, whereby the gas refrigerant is condensed and liquefied. Then, the pressure is reduced by the second pressure reducing device (5a) in the second expansion device (5) to become 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) passes through the bypass circuit (10) and the low-pressure refrigerant and heat which are drawn into the compressor (1) by the suction heat exchanger (11). The refrigerant is exchanged and the suction refrigerant is heated to be completely vaporized, and the condensed refrigerant itself is decompressed by the auxiliary capillary tube (12) and merges into the pipe side as a low temperature and low pressure liquid refrigerant, and the first throttle After passing through the bypass circuit (4c) in the device (4) and entering the outdoor heat exchanger (3), the outdoor blower (9)
While exchanging heat with the outdoor air blown from the outdoor air, the outdoor air is cooled to cool the outdoor air, and thereby the liquid refrigerant is vaporized and gasified, passing through the four-way switching valve (2) and the accumulator (7), and then the compressor ( A refrigeration cycle circuit for returning to 1) is constructed.

In addition, during such heating operation, for example, during defrost operation that is required when the outdoor air temperature is low and frost forms on the outdoor heat exchanger (3) (the flow of the refrigerant is the arrow indicated by the broken line in the figure). Direction), the high-temperature high-pressure gas refrigerant discharged from the compressor (1) passes through the three-way switching valve (13) in the state of being switched to the defrost side, and the first and second expansion devices (4), The first connected to the pipe side between (5)
Through the pipe (15) of the bypass circuit (14) and flow into the pipe side.

On the other hand, a part of the high-temperature high-pressure gas refrigerant discharged from the compressor (1) here passes through the bypass circuit (10) and is sucked into the compressor (1) by the suction heat exchanger (11). The refrigerant is heat-exchanged with the suction refrigerant to heat and completely vaporize the refrigerant, and it also condenses and liquefies itself, and the auxiliary capillary tube (1
The pressure is reduced by 2) to become a low-temperature low-pressure liquid refrigerant, which is mixed with the high-temperature high-pressure gas refrigerant passing through the pipe (15) of the first bypass circuit (14). Then, these combined gas refrigerants pass through the bypass circuit (4c) in the first expansion device (4) and enter the outdoor heat exchanger (3). At this time, the outdoor blower (9) is stopped. Then, the high temperature gas refrigerant melts the frost frosted on the surface of the outdoor heat exchanger (3) with the high temperature gas refrigerant, and this refrigerant condenses and liquefies to pass through the four-way switching valve (2) to the accumulator (7). It will be returned to the incoming compressor (1).

Therefore, during such defrosting, without switching the four-way switching valve (2) from the heating side to the cooling side,
Defrost operation can be entered so that there is no heat loss for switching. Further, since the low-temperature liquid refrigerant does not pass through the indoor heat exchanger (6), the problem is solved when cold air is blown to the indoor side as in the conventional case.

Furthermore, the inner diameter of the pipe (15) forming a part of the first bypass circuit (14) is made smaller than that of the discharge side pipe (1b), resulting in pressure loss, and the high pressure side pressure of the compressor (1). Rises and the input increases, so that the capacity of the compressor (1) increases and the defrost time can be shortened.

As for the defrost end signal, the temperature on the outlet side of the outdoor heat exchanger (3) during defrost is detected by a detection device such as a thermistor. Due to the increase in the side pressure, the outlet side temperature of the outdoor heat exchanger (3) may be abnormally stopped by the high pressure cut before reaching the end temperature. At this time, the discharge pressure control valve (16) in the second bypass circuit (17) branched from the middle of the first bypass circuit (14) is opened, and the accumulator (18) controls the flow rate by the auxiliary capillary tube (18). By releasing the pressure to the inlet pipe of 7) and maintaining the high-pressure side pressure constant, abnormal stop due to the high-pressure cut can be prevented.

In addition, the compression heat exchanger (11) allows the compressor (1)
Since the suction side pipe (1a) is configured to exchange heat with the high-temperature and high-pressure gas refrigerant discharged from the compressor (1), it is possible to prevent a liquid return phenomenon to the compressor (1) and to prevent a compressor trouble. Can be prevented.

As shown by (20) in the figure, if an electric heater is installed so as to face the indoor heat exchanger (6), the refrigerant will remain in the indoor heat exchanger (6) during defrost operation.
Since it does not pass through, the indoor blower (8) can be operated, and there is an advantage that the heating operation can be continued even during the defrost operation.

〔The invention's effect〕

As described above, according to the air conditioner of the present invention, the outdoor heat exchanger and the second expansion device are connected via the three-way switching valve connected between the refrigerant discharge pipe of the compressor and the four-way switching valve. A first bypass circuit that bypasses and connects to the connecting pipe, and a second bypass that is connected from the first bypass circuit to the suction side pipe of the compressor by bypass and that has a discharge pressure adjusting valve and auxiliary pressure reducing means. A circuit is provided, and during the heating operation, the three-way switching valve is opened to the four-way switching valve side to perform the heating operation, and during the defrost operation, the four-way switching valve is kept in the heating operation and the three-way switching valve is connected to the first bypass. Since the discharge pressure adjusting valve of the second bypass circuit is opened when the high pressure side pressure of the compressor reaches a predetermined high pressure value while performing the defrost operation by opening to the circuit side, it is possible to perform the heating operation, Warm If you frosted outdoor heat exchanger during operation, the four-way selector valve remains heating operation, the three-way valve to the first bypass circuit since the switching defrosting operation,
It is possible to prevent heat loss due to switching of the conventional four-way switching valve, and to prevent cold air from blowing into the room as in the conventional case. Moreover, during the defrost operation, the refrigerant does not lie in the indoor heat exchanger via the four-way switching valve, so the first
The defrosting refrigerant flowing to the bypass circuit does not run short, and quick defrosting is possible. If the high pressure rises excessively during defrosting, the discharge pressure adjusting valve is opened, and the auxiliary pressure reducing means limits the flow rate of the refrigerant to prevent it from flowing too much, maintaining the high pressure constant, Abnormal stop due to cutting can be prevented, and complete defrosting can be performed without extending the time.

Further, the first bypass circuit has a pipe having an inner diameter smaller than the inner diameter of the discharge side pipe of the compressor, resulting in pressure loss, the high pressure side pressure of the compressor increases, the input increases, The capacity of the machine is increased and the defrost time can be shortened.

Further, since the refrigerant sucked into the compressor can be heated and completely vaporized in the suction heat exchange section, liquid compression of the compressor can be prevented.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a refrigeration cycle circuit showing an 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, (1) is a compressor, (1a) is a suction side pipe, (1b) is a discharge side pipe, (2) is a four-way switching valve,
(3) is an outdoor heat exchanger, (4) and (5) are first and second expansion devices, (4a) and (5a) are first and second pressure reducing devices, and (4b) and (5b). ) Is a check valve, (6) is an indoor heat exchanger, (7) is an accumulator, (13) is a three-way switching valve,
(14) is the first bypass circuit, (15) is thin piping, (16)
Is the discharge pressure control valve, (17) is the second bypass circuit, (1
8) is an auxiliary decompression means. In the drawings, the same reference numerals indicate the same or corresponding parts.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Katsumi Kasano, Katsumi Kasano 6-566, Tehira, Wakayama, Wakayama Sanryo Electric Co., Ltd. Wakayama Works (72) Inventor, Hitoshi Kido, 6-5, Tehira, Wakayama, Wakayama Prefecture No. 66 Sanryo Electric Co., Ltd. Wakayama Works (72) Inventor Yoshimichi Nakagawa 6-5-6 Tehira, Wakayama City, Wakayama Sanryo Electric Co., Ltd. (56) Reference: JP-A-62-138660 (JP, A) JP-A-57-95555 (JP, A) JP-A-62-158958 (JP, A) Actually open 56-40360 (JP, U) Actual-open Sho-54-180345 (JP, U)

Claims (3)

[Claims] 1. A compressor, a four-way switching valve for switching the flow of high-temperature and high-pressure refrigerant discharged from the compressor, an outdoor heat exchanger provided with an outdoor blower, and a second pressure reducing valve for heating. In the air conditioner comprising a throttle device and an indoor heat exchanger equipped with an indoor blower, which are sequentially connected by a refrigerant pipe to form a refrigerant circuit, the refrigerant discharge pipe of the compressor and four-way switching. The first bypass circuit and the first bypass circuit, which are bypassed and connected to a pipe connecting the outdoor heat exchanger and the second expansion device via a three-way switching valve connected between the valves.
A bypass circuit connected from the bypass circuit to the suction side pipe of the compressor, and having a second bypass circuit having a discharge pressure adjusting valve and an auxiliary pressure reducing means, and during heating operation, the three-way switching valve is replaced with the four-way switching valve. Side to perform the heating operation, and during the defrost operation, the three-way switching valve is opened to the first bypass circuit side while the four-way switching valve is in the heating operation to perform the defrost operation, and the high-pressure side pressure of the compressor is set to a predetermined value. An air conditioner, wherein the discharge pressure adjusting valve of the second bypass circuit is opened when a high pressure value is reached. 2. The air conditioner according to claim 1, wherein the first bypass circuit has a pipe having an inner diameter smaller than that of the discharge side pipe of the compressor. 3. A refrigerant circuit is provided with a first expansion device for decompressing the refrigerant during cooling, and each of the first expansion device and the second expansion device has a bypass circuit for bypassing the respective decompression device, and Each bypass circuit has
A check valve that allows the flow of the refrigerant only to the outdoor side and the indoor side heat exchangers, respectively, and is bypassed between the refrigerant discharge pipe of the compressor and the pipe connecting the first and second expansion devices. The bypass circuit is provided with a suction heat exchange section for exchanging heat with the refrigerant suction pipe of the compressor and a decompression device for decompressing the refrigerant in the middle of the pipeline. The air conditioner according to claim 1 or 2.