CN101344340B - Air conditioner - Google Patents

Abstract

An air conditioner, which is formed by connecting a compressor (1), a four-way valve (8), an indoor heat exchanger (3), a pressure reducer (4), and an outdoor heat exchanger (5) through refrigerant piping The refrigeration cycle is provided with: a first bypass circuit (18) connecting the part between the outdoor heat exchanger and the pressure reducer with the discharge pipe of the compressor, and connecting the discharge pipe of the compressor with the suction part of the compressor The second bypass circuit (19), the bypass circuit has an opening and closing mechanism (7), and the air conditioner performs the heating and defrosting operation in the following manner, that is, the defrosting operation of the heating cycle is performed until the specified conditions are met, and then, Change the four-way valve (8) from the heating cycle to the cooling cycle, and close the pressure reducer, so that the temperature and pressure of the refrigerant in the outdoor heat exchanger can be increased without sending cold air to the room. The frost melts. In addition, the decompressor is opened at a predetermined opening to circulate a very small amount of refrigerant to the indoor heat exchanger, thereby improving the accuracy of defrosting completion determination.

Description

air conditioner

technical field

The present invention relates to an air conditioner capable of improving the defrosting capability and the accuracy of defrosting end determination control in a defrosting cycle capable of performing a defrosting operation in a heating cycle.

Background technique

Conventionally, in the refrigeration cycle of the heating operation of the air conditioner, the four-way valve circulates the high-temperature and high-pressure refrigerant discharged from the compressor to the indoor heat exchanger to condense the refrigerant into a high-pressure liquid refrigerant. The refrigerant flows to the outdoor expansion valve and adiabatically expands into a low-temperature and low-pressure refrigerant, then absorbs heat from the outdoor air in the outdoor heat exchanger, and returns to the compressor as a gaseous low-pressure refrigerant via the accumulator. At this time, when the outdoor air temperature is low such as below freezing point, moisture in the air turns into frost and condenses on the outdoor heat exchanger. The heat exchanging capacity of the heat exchanger after frosting is significantly reduced, and sufficient heating capacity cannot be obtained. Therefore, it is necessary to melt the condensed frost. At this time, conventional air conditioners generally adopt the method of reversing the four-way valve during the heating operation to form a refrigeration cycle, stopping the indoor fan and the outdoor fan to circulate the high-temperature and high-pressure refrigerant in the outdoor heat exchanger, thereby Melts frost and ice adhering to the heat exchanger.

There is an air conditioner that uses a defrosting method that does not need to switch the four-way valve. That is, the defrosting operation is performed by bypassing the exhaust gas while maintaining the heating cycle during heating operation. In this case, the heating cycle is maintained. until the end of the defrosting operation (for example, refer to Japanese Patent Laid-Open No. 2-17370).

FIG. 5 shows a conventional air conditioner described in the above publication. As shown in Figure 5, the refrigeration cycle consists of a compressor 1, a discharge pipe 2, an indoor heat exchanger 3, an electric expansion valve 4, a liquid pipe 15, an outdoor heat exchanger 5, an accumulator 6, a bypass circuit 16 and a switch Valve 17 constitutes. In the above structure, when the defrosting operation is performed during the heating operation, the four-way valve 8 still maintains the heating cycle, the outdoor expansion valve 4 is fully opened, the outdoor fan 14 stops, the indoor fan 13 operates with weak wind, and the bypass circuit 16 is opened. The closing valve 17 is opened, allowing the exhaust gas to flow into the bypass circuit. In this way, the indoor heating operation can be carried out continuously without switching the four-way valve 8, so bad problems such as oil cut-off can also be avoided.

However, with the above-mentioned conventional structure that switches to the refrigeration cycle during defrosting operation, the indoor temperature drops because the heating operation is temporarily stopped. In addition, since the four-way valve is reversed, there is a risk of refrigerant sound and compression. Oil cut-off of machine 1, liquid return of refrigerant, etc.

In addition, if the heating cycle is still performed during the defrosting operation, the pressure of the refrigerant circulating in the outdoor heat exchanger has dropped, and the temperature of the outdoor heat exchanger cannot be raised sufficiently, so there is a melting residue that will cause frost. Or it is difficult to judge the completion of defrosting.

Contents of the invention

In view of the above-mentioned problems, an object of the present invention is to provide an air conditioner capable of improving the accuracy of defrosting end judgment while preventing frost residue from remaining on an outdoor heat exchanger.

In order to solve the above-mentioned conventional technical problems, in the air conditioner of the present invention, a compressor, a four-way valve, an indoor heat exchanger, a decompressor, and an outdoor heat exchanger are connected by refrigerant piping in a refrigeration cycle. There are: a first bypass circuit that connects the part between the outdoor heat exchanger and the pressure reducer with the compressor discharge pipe, and a second bypass circuit that connects the compressor discharge pipe with the compressor suction part. Two bypass circuits, the bypass circuit part shared by the first bypass circuit and the second bypass circuit has an opening and closing mechanism, and the air conditioner performs heating and defrosting operation in the following manner, that is, defrosting of the heating cycle The frost operation is performed until the specified conditions are met, and then the four-way valve is turned into a cooling operation cycle, the opening and closing mechanism is opened, and the pressure reducer is closed or substantially closed.

In addition, in the air conditioner of the present invention, a common opening and closing mechanism is not provided on the bypass circuit shared by the first bypass circuit and the second bypass circuit, but the first bypass circuit and the second bypass circuit Opening and closing mechanisms are respectively arranged on the circuit.

Therefore, even if the refrigerant does not circulate in the indoor heat exchanger and the four-way valve is in a refrigeration cycle state, cold air will not be sent to the room, increasing the pressure of the refrigerant in the outdoor heat exchanger and increasing the temperature of the heat exchanger. This allows the frost to melt.

In addition, in the present invention, when a predetermined time elapses after the start of the heating and defrosting operation, or when the temperature detected by the piping temperature sensor attached to the outdoor heat exchanger becomes higher than a predetermined predetermined temperature, the pressure reducer is set to After the refrigerant is circulated to the indoor heat exchanger at a predetermined opening degree, the end of defrosting can be determined by using the temperature detected by the pipe temperature sensor of the outdoor heat exchanger, so that the end of defrosting can be accurately determined.

In addition, in the present invention, in particular, the opening and closing mechanism of the bypass circuit is made into a flow regulating valve that can be completely closed, so that the refrigeration cycle can be optimized.

In addition, in the present invention, in particular, the opening and closing mechanism of the bypass circuit is made as an electromagnetic two-way valve, so that the manufacturing cost can be reduced.

In addition, in particular, the pressure reducer is made as an expansion valve that can be completely closed, so that the refrigeration cycle can be optimized.

Description of drawings

Fig. 1 is a diagram showing a refrigeration cycle of an air conditioner according to an embodiment of the present invention.

Fig. 2 is a diagram showing a part of a refrigeration cycle of an air conditioner according to another embodiment of the present invention.

Fig. 3 is a diagram showing a part of a refrigeration cycle of an air conditioner according to still another embodiment of the present invention.

Fig. 4 is a control flow diagram of the embodiment of the present invention.

Fig. 5 is a refrigeration cycle diagram of a conventional air conditioner.

Detailed ways

Embodiments of the present invention will be described below with reference to the drawings. In addition, this invention is not limited to this embodiment.

FIG. 1 is a diagram showing a refrigeration cycle of an air conditioner according to an embodiment of the present invention. Solid arrows indicate refrigerant flow during a heating and defrosting cycle, and dotted arrows indicate refrigerant flow during a refrigeration cycle. In Fig. 1, a refrigeration cycle is formed by connecting a compressor 1, an indoor heat exchanger 3, a fully-closeable expansion valve 4 as a pressure reducer, an outdoor heat exchanger 5, and a four-way valve 8 through refrigerant piping. The first bypass circuit 18 is extended from the discharge pipe 2 of the compressor 1 to the connection pipe 4a between the outdoor heat exchanger 5 and the expansion valve 4, and an electromagnetic two-way valve 7 as an opening and closing mechanism is arranged in the middle of it. The capillary tube 9A and the check valve 10A for flow adjustment of the refrigerant. A second bypass circuit 19 is provided between the accumulator 6 and the portion between the electromagnetic two-way valve 7 and the capillary 9A. A capillary 9B for adjusting the flow rate of the refrigerant and a check valve 10B are also arranged on the second bypass circuit 19 . In this embodiment, the electromagnetic two-way valve 7 is set to be used for the opening and closing of the first bypass circuit 18 and the second bypass circuit 19, but the electromagnetic two-way valve 7 can also be provided separately so that the first bypass circuit 18 and the second bypass circuit 19 are respectively opened and closed. FIG. 2 shows an example in which the electromagnetic two-way valve 7 is disposed on the first bypass circuit 18 and the second bypass circuit 19 respectively. The example of FIG. 3 is also an example in which the electromagnetic two-way valve 7 is respectively arranged on the first bypass circuit 18 and the second bypass circuit 19, but the second bypass circuit 19 does not pass through a part of the first bypass circuit, but It is in separate communication with the compressor discharge pipe and the compressor suction.

In the above-mentioned structure, if the outdoor expansion valve 4 is opened at a predetermined opening while the four-way valve 8 is kept in the heating cycle, the high-temperature and high-pressure refrigerant in the indoor heat exchanger 3 will be transformed into a gas-liquid two-phase weakly high-temperature refrigerant. The state (+5°C to about 10°C) flows into the frosted outdoor heat exchanger 5 . Frost and ice adhering to the outdoor heat exchanger 5 melt due to the high-temperature refrigerant. However, at this time, since the refrigerant flowing in in a gas-liquid two-phase state releases heat due to liquefaction of the gas component, the liquid refrigerant component increases as it circulates through the heat exchanger, and when returning to the compressor 1, Liquid ingredients will make up the vast majority. Therefore, there are problems such as a liquid return phenomenon of the compressor 1 and insufficient discharge overheating (heating degree) caused by a drop in the discharge temperature, which affect reliability. In addition, as the discharge temperature decreases, the dryness of the refrigerant circulating from the outdoor expansion valve 4 to the outdoor heat exchanger 5 also decreases, and the frost-thawing and ice-defrosting capabilities of the outdoor heat exchanger 5 also decrease.

Therefore, by bypassing the discharge gas from the compressor 1 between the outdoor expansion valve 4 and the outdoor heat exchanger 5, the temperature and pressure of the refrigerant circulating in the outdoor heat exchanger 5 are increased to improve the defrosting capability. At the same time, the discharge gas is divided after flowing through the electromagnetic two-way valve 7 and a part of it flows into the suction side of the compressor 1 . In this way, the dryness of the compressor suction gas can be maintained, and the aforementioned reliability problems and discharge temperature drops can be prevented.

There are generally two problems with defrosting with this cycle. One problem is that defrosting capability is insufficient due to insufficient temperature rise of the outdoor heat exchanger 5 . Another problem is that it can be difficult to tell if the frosting has melted.

First, in the above-mentioned defrosting operation under the heating cycle, when the predetermined condition is satisfied, in the embodiment of the present invention, it means that the detected temperature of the pipe temperature sensor B12 installed on the outdoor heat exchanger 5 exceeds the specified temperature. When the state of temperature (e.g. 8°C) continues for a specified time (e.g. 1 minute) or exceeds the maximum time (e.g. 10 minutes), it is judged that the defrosting is completed, but the defrosting is included when the maximum time is exceeded. occasions that are not completely over.

Therefore, after the defrosting operation of the heating cycle is completed, the outdoor four-way valve 8 is reversed to perform the defrosting operation of the refrigeration cycle. Figure 1 shows the refrigeration cycle at this time. In this way, the high-temperature and high-pressure gas refrigerant discharged from the compressor 1 circulates in the outdoor heat exchanger 5 in a direction opposite to that at the time of defrosting in the heating cycle. That is, the refrigerant with the highest temperature flows to the most difficult-to-defrost portion serving as an outlet when the heating cycle is defrosted, thereby improving the defrosting capability. At this time, the electromagnetic two-way valve 7 on the bypass is kept open, so even if the compressor 1 is not stopped, the pressure difference is small, so that the refrigerant sound caused by the switching of the four-way valve 8 can be suppressed to a minimum . That is, in the defrosting operation, even in the heating cycle state, since the outdoor expansion valve 4 is opened at a predetermined opening degree and the electromagnetic two-way valve 7 as the opening and closing device is opened, the high pressure does not rise much and the low pressure does not drop much, This results in a state of "small pressure difference" between the high pressure side and the low pressure side. In addition, the oil shortage state of the compressor 1 does not occur.

At this time, the case of fully closing the outdoor expansion valve 4 and the case of slightly opening the outdoor expansion valve 4 are included. The purpose of completely closing the outdoor expansion valve 4 is to prevent the low-temperature and low-pressure refrigerant from flowing into the room at all, which has the advantages of completely shielding the sound of the refrigerant and avoiding indoor cold wind, but the refrigerant will accumulate in the outdoor heat exchanger 5. Therefore, it cannot continue to operate for a long time. In addition, since the refrigerant does not circulate in this state, it is also difficult to determine whether the outdoor heat exchanger 5 has completely completed defrosting. When the outdoor expansion valve 4 is slightly opened, on the contrary, since the refrigerant circulates indoors, there is a problem of refrigerant sound and cold wind, but this is not a problem if it is extremely small. However, long runs are also difficult in this case.

Thereafter, in the embodiment of the present invention, the outdoor expansion valve 4 is opened with a constant opening degree for defrosting determination. In this way, the outdoor heat exchanger 5 becomes the high-pressure side. If the frost is completely melted, the temperature will be 10°C or higher, and if the frost has not melted, the temperature will be about 0°C to 4°C. Therefore, even if the temperature of the piping temperature sensor is considered The deviation is also sufficient to determine the end of defrosting. If it is determined that the defrosting is not over, then switch the four-way valve 8 and return the electromagnetic two-way valve 7 on the bypass circuit to the closed state to perform refrigeration cycle defrosting. The piping temperature sensor used at this time is the piping temperature sensor A11 at the outlet of the heat exchanger. In addition, since the judgment can be made in a short time (for example, 30 seconds), there will be no trouble in the room.

Fig. 4 shows an actual control flow chart of the refrigeration cycle using the above structure. In FIG. 4 , the defrosting determination is performed during the heating operation, and the defrosting operation starts ( S1 ). Next, when the temperature detected by the outdoor piping temperature sensor B12 becomes equal to or higher than the predetermined temperature t1 or the predetermined time T1 has elapsed in the defrosting operation (S2), the four-way valve 8 is switched to the refrigeration cycle (S3). In this way, the direction of the refrigerant flowing in the outdoor heat exchanger 5 is reversed. Since the high-temperature discharged refrigerant flows to the outlet side during the defrosting operation of the heating cycle, where the melted residue of frost tends to form, efficient defrosting can be performed. At this time, the expansion valve 4 is completely closed (S4) so that the refrigerant does not flow into the room. Afterwards, when the temperature of the outdoor pipe temperature sensor A11 becomes equal to or higher than the predetermined value t2 or when the defrosting operation has elapsed for the predetermined time T2 (S5), the expansion valve 4 is opened to a predetermined degree (so that the refrigerant flows slightly, for example, in the present invention, 80 pulses) (S6), so that very little refrigerant circulates to the indoor side. In this way, the refrigerant circulates in the outdoor heat exchanger 5, and it is possible to accurately determine whether the frost adhering to the outdoor heat exchanger 5 has melted or not by using the temperature detected by the piping temperature sensor A11 (S7). If the temperature detected by the outdoor piping temperature sensor A11 is equal to or higher than the predetermined temperature t3, the process returns directly to the heating operation (S8). As described above, in this embodiment, since the four-way valve 8 is reversed to perform the refrigeration cycle during the defrosting operation of the heating cycle, there will be no problems such as refrigerant noise and indoor cold wind, and the outdoor heat can be improved. The defrosting capability of the exchanger 5 can be improved, and the precision of its defrosting judgment control can be improved.

Since the electromagnetic two-way valve 7 on the bypass of the present embodiment is used as a flow regulating valve that can be completely closed, the capillary tubes 9A and 9B are not required, cost can be reduced, and the refrigeration cycle can be optimized. Since one electromagnetic two-way valve is also used as the opening and closing mechanism of the two bypass circuits, the manufacturing cost can be reduced. In addition, since the pressure reducer is made as an expansion valve that can be completely closed, the refrigeration cycle can be optimized.

Claims (8)

1. An air conditioner, characterized in that, In the refrigerating cycle formed by connecting the compressor (1), four-way valve (8), indoor heat exchanger (3), pressure reducer (4), and outdoor heat exchanger (5) through refrigerant piping, a : a first bypass circuit (18) connecting a portion between the outdoor heat exchanger and the pressure reducer to the discharge pipe (2) of the compressor; and a second bypass circuit (19) communicating the discharge pipe of said compressor with the compressor suction, The bypass circuit part shared by the first bypass circuit and the second bypass circuit has an opening and closing mechanism (7), When the first time has elapsed since the defrosting operation was started during the heating cycle, or when the temperature detected by the first piping temperature sensor (12) attached to the outdoor heat exchanger reaches a predetermined first temperature or higher In the case of refrigerating cycle, the four-way valve is turned on, the opening and closing mechanism is opened, and the pressure reducer is closed or substantially closed. When the second time elapses after switching the four-way valve to change from the heating cycle to the cooling cycle, or when the detected temperature of the second piping temperature sensor (11) installed on the outdoor heat exchanger When the predetermined second temperature is reached or higher, the pressure reducer is opened to a predetermined degree to circulate the refrigerant to the indoor heat exchanger, and then the temperature detected by the second piping temperature sensor is used to determine whether end of defrosting. 2. The air conditioner according to claim 1, wherein the opening and closing mechanism is made as a flow regulating valve that can be completely closed. 3. The air conditioner according to claim 1, wherein the opening and closing mechanism is an electromagnetic two-way valve. 4. The air conditioner according to claim 1, wherein the pressure reducer is made as an expansion valve that can be completely closed. 5. An air conditioner, characterized in that, In the refrigerating cycle composed of compressor (1), four-way valve (8), indoor heat exchanger (3), pressure reducer (4), and outdoor heat exchanger (5) connected by refrigerant piping, set have: a first bypass circuit (18) connecting the part between the outdoor heat exchanger and the pressure reducer to the discharge pipe (2) of the compressor; and a second bypass circuit (19) communicating the discharge pipe of said compressor with the compressor suction, The first bypass circuit and the second bypass circuit respectively have opening and closing mechanisms (7), When the first time has elapsed since the defrosting operation was started during the heating cycle, or when the temperature detected by the first piping temperature sensor (12) attached to the outdoor heat exchanger reaches a predetermined first temperature or higher In the case of refrigerating cycle, the four-way valve is turned on, the opening and closing mechanism is opened, and the pressure reducer is closed or substantially closed. When the second time elapses after switching the four-way valve to change from the heating cycle to the cooling cycle, or when the detected temperature of the second piping temperature sensor (11) installed on the outdoor heat exchanger When the predetermined second temperature is reached or higher, the pressure reducer is opened to a predetermined degree to circulate the refrigerant to the indoor heat exchanger, and then the temperature detected by the second piping temperature sensor is used to determine whether end of defrosting. 6. The air conditioner according to claim 5, wherein the opening and closing mechanism is made as a flow regulating valve that can be completely closed. 7. The air conditioner according to claim 5, wherein the opening and closing mechanism is an electromagnetic two-way valve. 8. The air conditioner according to claim 5, wherein the pressure reducer is made as an expansion valve that can be completely closed. the

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