JP2014119152A - Air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air conditioner that can control the amount of a refrigerant using a receiver and also defrost a hot gas bypass without having its structure made complicated.SOLUTION: There is provided an air conditioner provided with a bypass circuit 10 coupling first piping 11, which connects a throttle device 5 and an outdoor heat exchanger 4 constituting a refrigerant circuit together, and second piping 12, which connects a four-way valve 9 and an indoor heat exchanger 7 together, to each other. The bypass circuit 10 includes a receiver 13 which reserves a refrigerant, a first coupling pipe 14 which couples the receiver 13 and first piping 11 to each other and a second coupling pipe 15 which couples the receiver 13 and the second pipe 12 to each other, and a first flow control device 16 and a second flow control device 17 which are interposed in the first coupling pipe 14 and second coupling pipe 15 respectively, and control flow rates of the refrigerant, the receiver 13 being arranged to be in thermal contact with piping (suction piping 18) having a temperature lower than a discharge-side piping temperature of a compressor 3.

Description

  The present invention relates to an air conditioner that can be defrosted by a hot gas bypass system and can adjust the amount of refrigerant circulating in a refrigerant circuit.

  Most current air conditioners have a refrigerant circuit configured to switch between cooling and heating. Also, the amount of refrigerant required for the refrigerant circuit varies greatly depending on the size of the condenser. In a general air conditioner, the refrigerant flow path between the indoor heat exchanger and the outdoor heat exchanger that constitute the refrigerant circuit The volume of is different. Therefore, the amount of refrigerant required for the refrigerant circuit varies greatly between the cooling operation and the heating operation. Even in the same operation mode, the amount of refrigerant required for the refrigerant circuit varies depending on whether the rotation speed of the compressor is high or low.

  In response to the above problem, Patent Document 1 discloses a refrigerant storage device (receiver) connected in flow communication with a refrigerant circuit by at least one refrigerant line, and a refrigerant flow control device arranged in at least one refrigerant line. The refrigerant flow control device is described as a refrigerant vapor compression system having an open position where the refrigerant flows through the refrigerant line and a closed position where the refrigerant flow through the refrigerant line is blocked.

  Moreover, in the conventional air conditioner, as shown in Patent Document 2, as a method of removing frost adhering to the evaporator, a part of the refrigerant discharged from the compressor is bypassed to the inlet side of the evaporator. There is a quick defrosting method (hot gas bypass defrosting method) that removes frost and a reverse defrosting method that switches a four-way valve and allows high-temperature refrigerant discharged from the compressor to flow into the evaporator. Among these, the hot gas bypass defrosting method has the advantage that it is not necessary to switch the operation mode and is highly convenient for the user.

JP 2011-521194 A JP 2002-107014 A

  However, in the case where the refrigerant amount can be adjusted using the receiver as in Patent Document 1 and hot gas bypass defrosting is enabled as in Patent Document 2, many gas pipes and flow rate adjusting devices are required. There is a problem that the structure becomes complicated and the manufacturing cost becomes high.

  Therefore, in view of the above, an object of the present invention is to provide an air conditioner capable of adjusting the refrigerant amount using a receiver and capable of hot gas bypass defrosting without complicating the structure.

  In order to achieve the above object, in the present invention, a compressor, a four-way valve, an indoor heat exchanger, an expansion device, and an outdoor heat exchanger are sequentially connected by a pipe to form a refrigerant circuit in which a refrigerant flows. An air conditioner provided with a defrosting bypass circuit that connects a first pipe connecting an indoor heat exchanger and a second pipe connecting the expansion device and an outdoor heat exchanger. The bypass circuit includes a receiver for storing refrigerant, a first connection pipe for connecting the receiver and the first pipe, a second connection pipe for connecting the receiver and the second pipe, the first connection pipe and the first pipe. A first flow rate adjusting device and a second flow rate adjusting device, each of which is interposed in the two connecting pipes, for adjusting the flow rate of the refrigerant, wherein the receiver is connected to a pipe whose temperature is lower than the pipe temperature on the discharge side of the compressor. Placed in thermal contact The features.

  According to the above configuration, the receiver is interposed in the bypass circuit that connects the first pipe that connects the four-way valve and the indoor heat exchanger and the second pipe that connects the expansion device and the outdoor heat exchanger. It is not necessary to provide a simple pipe. Furthermore, the flow rate adjusting device that opens and closes the bypass circuit can be used as a flow rate adjusting device for adjusting the refrigerant amount of the receiver, and the number of components can be reduced.

  In the present invention, the receiver is disposed so as to be in thermal contact with a pipe having a temperature lower than the pipe temperature on the discharge side of the compressor (hereinafter referred to as a low temperature pipe). In other words, since the refrigerant discharged from the compressor is in a high-temperature and high-pressure gas state, it cannot be stored as a liquid refrigerant simply by being guided to a receiver interposed in the bypass circuit. Therefore, in the present invention, by bringing the receiver into thermal contact with the low-temperature pipe, the receiver can be cooled, and the refrigerant can be liquefied and stored in the receiver. As a specific configuration, for example, the receiver may be disposed so as to be in thermal contact with a suction pipe connecting the four-way valve and the compressor suction side.

  Here, thermally contacting means contacting both directly or indirectly so that heat can be exchanged between the receiver and the low-temperature pipe. Specifically, the receiver is indirectly contacted with the suction pipe by welding with a copper brazing material, or a concave surface that allows the suction pipe to be in close contact with the receiver is formed. The method of fixing in the state made to contact can be illustrated.

  Moreover, the control apparatus which controls a 1st flow control apparatus and a 2nd flow control apparatus was provided, and the control apparatus was discharged from the compressor by opening both the 1st flow control apparatus and the 2nd flow control apparatus. It is good also as a structure which can perform the hot gas bypass defrost which introduce | transduces at least one part of a refrigerant | coolant into an outdoor heat exchanger through a bypass circuit.

  More specifically, during the heating operation, when the control device determines that hot gas bypass defrosting is necessary, the direction of the refrigerant flowing through the refrigerant circuit remains unchanged, and the first flow rate adjustment device and the second flow rate adjustment device Open both of them. Thereby, a highly convenient air conditioner can be obtained. Here, controlling the flow rate adjusting device means controlling the flow rate of the refrigerant flowing through the connecting pipe by adjusting the opening degree of the flow rate adjusting device.

  The expansion device may be controlled by the control device, and the control device may operate the expansion device in a direction to close from the state immediately before the start of hot gas bypass defrosting at the time of hot gas bypass defrosting. That is, the operation mode continues the same operation mode as that immediately before starting the hot gas bypass defrosting, and operates the expansion device in the direction to close from the state immediately before the start of hot gas bypass defrosting to flow through the outdoor heat exchanger. The defrosting of the outdoor heat exchanger can be completed quickly by suppressing the refrigerant flow rate (the amount of refrigerant flowing per unit time) and increasing the refrigerant flow rate passing through the bypass circuit accordingly.

  Further, the control device performs at least one of the first flow rate adjustment device and the second flow rate adjustment device at the time of hot gas bypass defrosting or the throttle device is fully closed. Also good. Here, to fully open the flow rate adjusting device means to maximize the opening degree of the flow rate adjusting device. Thereby, the hot gas refrigerant | coolant flow volume which flows in into an outdoor heat exchanger can be increased. If the above two controls are performed, the flow rate of the hot gas refrigerant flowing into the outdoor heat exchanger can be maximized, and defrosting can be performed more quickly.

  The air conditioner of the present invention controls the first flow rate adjustment device and the second flow rate adjustment device, so that the refrigerant can be accumulated in the receiver, or the refrigerant accumulated in the receiver can be returned to the refrigerant circuit. The refrigerant amount can be adjusted according to the operation mode.

  Specifically, when the optimal refrigerant amount is smaller during the heating operation than during the cooling operation, the control device opens the second flow rate adjustment device and closes the first flow rate adjustment device. When the refrigerant is filled in the receiver, the refrigerant in the receiver is returned to the refrigerant circuit during the cooling operation, and the optimal refrigerant amount is smaller during the cooling operation than during the heating operation, the first flow rate adjustment device is By opening and closing the second flow rate adjusting device, the refrigerant may be filled in the receiver during the cooling operation, and the refrigerant in the receiver may be returned to the refrigerant circuit during the heating operation.

  Here, the optimum refrigerant amount is the “air conditioning capacity” of the refrigerant amount (circulating refrigerant amount) that actually circulates in the refrigerant circuit, which is obtained by subtracting the refrigerant amount stored in the receiver from the refrigerant amount enclosed in the refrigerant circuit. ”/“ Power consumption ”means the amount of refrigerant that maximizes the COP (coefficient of performance).

  When the optimum refrigerant amount is compared between the cooling operation and the heating operation, it is possible to compare the optimum refrigerant amount when the rated operation is performed for both the cooling and heating operation. Here, the rated operation means an operation in which the rotation speed of the compressor is driven at a preset constant value. As the rotation speed of the compressor, a standard rotation speed is set with high operation efficiency between the minimum rotation speed and the maximum rotation speed.

  As described above, the air conditioner of the present invention includes a receiver in a bypass circuit that bypasses at least a part of the refrigerant discharged from the compressor to the inlet side of the outdoor heat exchanger, and the receiver is connected to the low-temperature pipe. Since it arrange | positions so that it may contact thermally, it becomes possible to provide the air conditioner which can adjust refrigerant | coolant amount using a receiver and can perform a hot gas bypass defrost, without complicating a structure.

The figure which shows the refrigerant circuit of the air conditioner of this invention Control block diagram of the air conditioner of the present invention

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a refrigerant circuit diagram showing an embodiment of an air conditioner according to the present invention. As illustrated, the air conditioner of the present embodiment is a single-type air conditioner in which one indoor unit 2 is connected to one outdoor unit 1, and includes a compressor 3 housed in the outdoor unit 1, an outdoor unit The heat exchanger 4 and the expansion device 5 are connected in series in this order by refrigerant piping, and further, the indoor heat exchanger 7 accommodated in the indoor unit 2 is connected by piping from the expansion device 5 through the two-way valve 6, The refrigerant circuit is configured by connecting the pipe from the heat exchanger 7 to the outdoor compressor 3 through the three-way valve 8 again.

  The compressor 3 is connected to the refrigerant circuit via a four-way valve 9 that is a switching valve. By switching the four-way valve 9, either direction of the outdoor heat exchanger 4 side or the indoor heat exchanger 7 side is selected. The compressed refrigerant can be sent out. By switching the four-way valve 9, the outdoor heat exchanger 4 and the indoor heat exchanger 7 are used as a condenser or an evaporator.

  Specifically, in FIG. 1, the high-temperature refrigerant discharged from the compressor 3 is circulated in the direction indicated by the solid line in the figure, and passes through the outdoor heat exchanger 4 as a condenser and the expansion device 5 and the indoor heat as an evaporator. Cooling operation is realized by flowing into the exchanger 7. In addition, the refrigerant discharged from the compressor 3 is circulated in the direction of the broken arrow shown in the figure, and flows into the outdoor heat exchanger 4 as an evaporator via the indoor heat exchanger 7 as a condenser and the expansion device 5. By this, heating operation is realized.

  In this invention, the bypass circuit 10 which connects the 1st piping 11 which connects the expansion apparatus 5 and the outdoor heat exchanger 4, and the 2nd piping 12 which connects the four-way valve 9 and the indoor heat exchanger 7 is provided. . The bypass circuit 10 includes a receiver 13 that stores refrigerant, a first connection pipe 14 that connects the receiver 13 and the first pipe 11, a second connection pipe 15 that connects the receiver 13 and the second pipe 12, and a first connection. A first flow rate adjusting device 16 and a second flow rate adjusting device 17 are provided, which are interposed in the pipe 14 and the second connecting pipe 15, respectively, for adjusting the flow rate of the refrigerant.

  The receiver 13 is welded with a copper brazing material 19 to a suction pipe 18 that connects the four-way valve 9 serving as a low-temperature pipe and the suction side of the compressor 3. Thereby, heat exchange is possible between the receiver 13 and the suction pipe 18. Therefore, the high-temperature refrigerant discharged from the compressor 3 can be cooled and liquefied. Examples of the low-temperature pipe include a suction pipe 18, an outdoor heat exchanger inlet-side pipe, an outdoor heat exchanger outlet-side pipe, and the like during heating operation, and during the cooling operation, the suction pipe 18 and the outdoor heat exchanger outlet. There is a second pipe 12 connecting the side pipe, the four-way valve 9 and the indoor heat exchanger 7. Therefore, as the low-temperature pipe suitable for both cooling and heating, the suction pipe 18 is good, and the outdoor heat exchanger outlet side pipe may be used.

  As shown in FIG. 2, the air conditioner includes a control device 20 that controls the operation of the refrigeration circuit and controls the air conditioning operation. The air conditioner includes an outdoor heat exchanger temperature sensor 21 that detects the temperature of the outdoor heat exchanger 4, an indoor heat exchanger temperature sensor 22 that detects the temperature of the indoor heat exchanger 7, and refrigerant discharged from the compressor 3. A discharge temperature sensor 23, a room temperature sensor 24, and an outside air temperature sensor 25 for detecting the discharge temperature are provided.

  The control device 20 is composed of a microcomputer equipped with a CPU, a memory, and the like. Based on outputs of these temperature sensors, remote controllers, operation signals of operation switches of the main body, and the like according to a desired air conditioning operation, the compressor 3, The operation of the refrigerant circuit is controlled by controlling the operations of the blower 26, the expansion device 5, the first flow rate adjusting device 16, and the second flow rate adjusting device 17.

  Generally, the capacity of the outdoor heat exchanger 4 is larger than the capacity of the indoor heat exchanger 7. Therefore, more refrigerant is required during the cooling operation. Also in the present embodiment, the optimum refrigerant amount during the cooling rated operation is set to be larger than the optimum refrigerant amount during the heating rated operation. Here, the rated operation means an operation in which the rotation speed of the compressor is driven at a preset constant value. As the rotation speed of the compressor, a standard rotation speed is set with high operation efficiency between the minimum rotation speed and the maximum rotation speed.

  That is, the cooling operation and the dehumidifying operation are the air conditioning operation with a large amount of the optimum refrigerant, and the heating operation is the air conditioning operation with a small amount of the optimum refrigerant. The internal volume of the receiver 13 is set to the same volume as the volume difference between the optimum refrigerant amount in the cooling rated operation and the optimum refrigerant amount in the heating rated operation.

  The expansion device 5 is a device that adjusts the flow rate of the refrigerant. In this embodiment, an expansion valve is used. However, the expansion device 5 is not limited thereto, and a plurality of capillary tubes may be arranged to switch the flow path. The first flow rate adjusting device 16 and the second flow rate adjusting device 17 control the flow of the refrigerant in the first connecting pipe 14 and the second connecting pipe 15 by opening and closing.

  That is, the first flow rate adjusting device 16 and the second flow rate adjusting device 17 adjust the pressure of the refrigerant in the receiver 13, and use an expansion valve, a flow rate adjustment valve, a stop valve, and the like. In the present embodiment, the first flow rate adjusting device 16 and the second flow rate adjusting device 17 are configured to use the same type of needle valve and to accurately control the opening degree by the stepping motor with the fully open position as a reference.

  When the air conditioner having the above configuration performs the heating operation, the optimum refrigerant amount is smaller than that during the cooling operation. Therefore, it is necessary to suppress the circulating refrigerant amount by storing the refrigerant in the receiver 13. During the heating operation, the second pipe 12 has a higher pressure than the first pipe 11. Therefore, by opening the high-pressure side second flow rate adjusting device 17 and closing the first flow rate adjusting device 16 during the heating operation, the refrigerant discharged from the compressor 3 is introduced into the receiver 13 to be cooled, and the liquid refrigerant is It collects in the receiver 13. That is, the heating operation can be performed in a state where the receiver 13 is filled with the refrigerant.

  On the other hand, during the cooling operation, the optimum refrigerant amount is larger than that during the heating operation. Therefore, it is necessary to increase the circulating refrigerant amount by returning the refrigerant from the receiver 13 to the refrigerant circuit. Further, during the cooling operation, the first pipe 11 has a higher pressure than the second pipe. Therefore, as described above, when the second flow rate adjustment device 17 is opened and the first flow rate adjustment device 16 is closed during the cooling operation, the second flow rate adjustment device 17 is now on the low pressure side. Therefore, the refrigerant is returned to the refrigerant circuit without accumulating in the receiver 13, and the amount of circulating refrigerant increases.

  As described above, when the optimum refrigerant amount during the cooling rated operation is set to be larger than the optimum refrigerant amount during the heating rated operation, the second flow rate adjustment device 17 is opened and the first flow rate adjustment device 16 is opened. By closing the refrigerant, the refrigerant can be stored in the receiver 13 during the heating operation to suppress the circulating refrigerant amount, and during the cooling operation, the refrigerant can be returned from the receiver 13 to the refrigerant circuit to increase the circulating refrigerant amount.

  When the heating operation is continued, the outdoor heat exchanger 4 starts frosting. When the outdoor heat exchanger 4 is frosted and the temperature detected by the temperature sensor 21 of the outdoor heat exchanger reaches a certain temperature T1, the control device 20 controls the first flow rate adjusting device 16 and the second flow rate adjusting device 17 to be set. Both are open. Thereby, first, the refrigerant stored in the receiver 13 is introduced into the outdoor heat exchanger 4, and then the high-temperature refrigerant gas discharged from the compressor 3 is introduced into the outdoor heat exchanger 4, and the outdoor heat exchanger 4. The hot gas bypass defrosting operation is started to melt the frost that has formed on the discharge gas with the discharge gas.

  The control device 20 ends the hot gas bypass defrosting operation for a predetermined time or when the outdoor heat exchanger 4 reaches a predetermined temperature T2 (T1 <T2). The flow rate adjusting device 16 is closed and the heating operation is resumed.

  Note that the control device 20 may operate the expansion device 5 in the direction of closing from the state immediately before the start of the hot gas bypass defrosting during the hot gas bypass defrosting operation. At this time, the control device 20 may control the first flow rate adjustment device 16 and the second flow rate adjustment device 17 to be fully opened, the throttle device 5 to be fully closed, or both. Thereby, the refrigerant | coolant flow rate which passes the bypass circuit 10 can be increased, and the defrosting of the outdoor heat exchanger 4 can be completed rapidly. Note that if the first flow rate adjusting device and the second flow rate adjusting device are fully closed and the expansion device is also fully closed, the refrigerant will not flow, so care must be taken.

  In the hot gas bypass defrosting, as the defrosting method, the operation mode is not switched, so that cold air blows out from the indoor unit and does not impair the convenience of the user, and the start-up of the heating operation is fast. preferable. Therefore, you may employ | adopt only a hot gas bypass defrost system as a defrost system.

  On the other hand, in the hot gas bypass defrosting method, when the refrigerant temperature discharged from the compressor 3 is low, the amount of frost formation is extremely large, or the outside air temperature is extremely low, the energy of the refrigerant at the time of defrosting May become insufficient and defrosting may be prolonged.

  Therefore, when the hot gas bypass defrosting operation is executed a predetermined number of times or when the total accumulated time of the hot gas bypass defrosting operation reaches a predetermined time, the control device 20 performs the reverse defrosting operation for the next defrosting operation. You may make it perform. Further, when the outside air temperature at the start of the defrosting operation is equal to or lower than the predetermined temperature, reverse defrosting can be performed instead of the hot gas bypass defrosting operation. In this way, good comfort can be maintained during heating operation.

  The present invention is not limited to the above embodiment, and many modifications and changes can be made to the above embodiment within the scope of the present invention. Specifically, the optimum refrigerant amount during the cooling rated operation may be set to be smaller than the optimum refrigerant amount during the heating rated operation. In this case, by opening the first flow rate adjusting device 16 and closing the second flow rate adjusting device 17, the refrigerant is stored in the receiver 13 during the cooling operation to suppress the amount of circulating refrigerant, and the refrigerant is received at the receiver 13 during the heating operation. It is possible to return to the refrigerant circuit and increase the amount of circulating refrigerant.

Moreover, in the said embodiment, although the one end side of the 1st connection pipe 14 and the 2nd connection pipe 15 is connected to the 1st piping 11 and the 2nd piping 12, respectively, the other end side is each connected to the receiver 13 individually. Not limited to this, for example, after the other end sides of the first connecting pipe 14 and the second connecting pipe 15 are assembled, it is possible to connect to the receiver 13 as a single connecting pipe.
In the present embodiment, the refrigerant amount is adjusted at the time of switching between the cooling operation and the heating operation. However, the present invention is not limited to this, and during the same operation mode, the receiver 13 can be used according to the rotational speed of the compressor. The amount of refrigerant stored inside may be adjusted.

DESCRIPTION OF SYMBOLS 1 Outdoor unit 2 Indoor unit 3 Compressor 4 Outdoor heat exchanger 5 Throttle device 6 Two-way valve 7 Indoor heat exchanger 8 Three-way valve 9 Four-way valve 10 Bypass circuit 11 First pipe 12 Second pipe 13 Receiver 14 First connection pipe DESCRIPTION OF SYMBOLS 15 2nd connection pipe 16 1st flow regulating device 17 2nd flow regulating device 18 Suction piping 19 Brazing material 20 Control apparatus 21 Outdoor heat exchanger temperature sensor 22 Indoor heat exchanger temperature sensor 23 Discharge temperature sensor 24 Room temperature sensor 25 Outside temperature Sensor 26 Blower

Claims (5)

  A compressor, a four-way valve, an indoor heat exchanger, an expansion device, and an outdoor heat exchanger are sequentially connected by piping to form a refrigerant circuit in which a refrigerant flows, and a first piping that connects the expansion device and the outdoor heat exchanger; An air conditioner provided with a defrosting bypass circuit that connects between the four-way valve and a second pipe connecting the indoor heat exchanger, wherein the bypass circuit includes a receiver for storing refrigerant; The first connecting pipe that connects the receiver and the first pipe, the second connecting pipe that connects the receiver and the second pipe, and the refrigerant interposed in the first connecting pipe and the second connecting pipe, respectively. A first flow rate adjusting device and a second flow rate adjusting device for adjusting a flow rate, wherein the receiver is arranged to be in thermal contact with a pipe having a temperature lower than a pipe temperature on a discharge side of the compressor; Air conditioner characterized by.   A control device for controlling the first flow rate adjustment device and the second flow rate adjustment device is provided, and the control device is discharged from the compressor by opening both the first flow rate adjustment device and the second flow rate adjustment device. 2. The air conditioner according to claim 1, wherein hot gas bypass defrosting that introduces at least a part of the refrigerant into the outdoor heat exchanger through the bypass circuit can be performed.   The throttle device is controlled by the control device, and the control device operates the throttle device in a direction to close from a state immediately before the start of hot gas bypass defrosting at the time of hot gas bypass defrosting. Air conditioner as described in.   The control device performs at least one of the first flow rate adjustment device and the second flow rate adjustment device to be fully opened or the throttle device to be fully closed during hot gas bypass defrosting. The air conditioner according to claim 3, wherein   When the optimal refrigerant amount is smaller during the heating operation than during the cooling operation, the control device opens the second flow rate adjustment device and closes the first flow rate adjustment device, so that the When the refrigerant is filled in the receiver, the refrigerant in the receiver is returned to the refrigerant circuit during the cooling operation, and the optimum refrigerant amount is smaller during the cooling operation than during the heating operation, the first flow rate adjusting device The refrigerant is filled in the receiver during the cooling operation by opening the second flow rate adjusting device and the refrigerant in the receiver is returned to the refrigerant circuit during the heating operation. The air conditioner described in Crab.

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