JP2008138921A - Air conditioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an air conditioner capable of preventing degradation of both of heating capacity and defrosting capacity, in particular when the temperature of the outside air is low. <P>SOLUTION: This air conditioner 100 comprises a main circuit constituted by successively connecting a compressor 11, a four-way valve 13, a load-side heat exchanger 52, a load-side throttling device 51, a refrigerant heat exchanger 16, a heat source-side throttling device 15 and a heat source-side heat exchanger 14 by gas piping 2 and liquid piping 1, an injection circuit constituted by successively connecting a throttling device 21 for bypassing, the refrigerant heat exchanger 16, an opening and closing valve 23 (first opening and closing valve) and an injection port of the compressor 11 by an injection pipe 20 branching the liquid piping 1 between the refrigerant heat exchanger 16 and the load-side throttling device 51, and a defrosting circuit constituted by successively connecting the heat source-side heat exchanger 14, an opening and closing valve 31 (second opening and closing valve), and the compressor 11 by a bypass pipe 30 branching the gas piping 2 between the four-way valve 13 and the load-side heat exchanger 50. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an air conditioner, and more particularly to an air conditioner capable of melting frost adhering to a heat source side heat exchanger mounted on a heat source side unit with high efficiency.

  Conventionally, a compressor, a load side heat exchanger (indoor heat exchanger), a heat source side expansion device (pressure reducing valve), and a heat source side heat exchanger (outdoor heat exchanger) are sequentially connected to the compressor. There is an air conditioner including a bypass pipe (defrost circuit) that branches a connected discharge side pipe and is connected between a heat source side expansion device and a heat source side heat exchanger. In such an air conditioner, defrosting operation in which frost adhering to the heat source side heat exchanger is melted by introducing the refrigerant discharged from the compressor (hot gas) to the heat source side heat exchanger in the bypass pipe is performed. To be done.

  As such, "a refrigerant circuit is formed by a compressor, a four-way valve, an outdoor heat exchanger, a throttle and an indoor heat exchanger, and a cooler is configured using a circuit below the outdoor heat exchanger, In a heat pump air conditioner that forms a bypass circuit that leads a part of the discharge gas of the compressor to the suction side of the compressor through the cooler, an electromagnetic on-off valve, and a throttle, when the temperature of the compressor rises The electromagnetic on-off valve in the bypass circuit is opened, the refrigerant liquefied by the cooler is bypassed to the suction side of the compressor to cool the compressor, and the electromagnetic on-off valve in the bypass circuit is opened during defrost operation. And an operation method of a heat pump type air conditioner in which frost in the lower part of the outdoor heat exchanger is melted with the discharged refrigerant gas introduced into the cooler has been proposed (for example, see Patent Document 1).

  In addition, “in an air conditioning apparatus in which an air conditioning refrigerant circuit includes a compressor, an air conditioning switching valve, an outdoor heat exchanger, an expansion valve, a plurality of indoor heat exchangers, and an accumulator, a pipe that connects the compressor and the air conditioning switching valve. A bypass circuit that branches from the outdoor heat exchanger and returns to the accumulator without passing through the plurality of indoor heat exchangers, and a bypass valve provided in the middle of the bypass circuit is connected to the indoor heat exchanger. An air conditioner that opens in accordance with a decrease in the number of operating units and heats the refrigerant passing through the bypass circuit by releasing heat to the outside by the outdoor heat exchanger is proposed (for example, see Patent Document 2). .

JP-A-6-341740 (2nd page, Fig. 1) Patent No. 3791019 (page 3, Fig. 1)

  The operation method of the heat pump air conditioner described in Patent Document 1 bypasses the refrigerant liquefied by the cooler during the heating operation to the compressor, and prevents an abnormal rise in the temperature of the compressor and flows into the cooler. The frost adhering to the lower part of the outdoor heat exchanger and the drain pan is reliably melted by the refrigerant. However, in a cold district where the outside air temperature is minus 10 ° C. or lower (hereinafter referred to as low outside air), the flow rate of the refrigerant sucked into the compressor decreases as the outside air decreases. And there existed a problem that both defrosting ability fell. That is, in the case of low outside air, heat is exchanged between the low outside air and the refrigerant, and the density of the refrigerant is reduced by lowering the evaporation temperature and low pressure of the refrigerant.

  In the air conditioner described in Patent Document 2, the refrigerant is caused to flow into the outdoor heat exchanger by the bypass circuit, and the heat stored in the refrigerant is released to the outside by the outdoor heat exchanger. Certainly, it is possible to use the heat released by the outdoor heat exchanger for the defrosting operation. However, as in the technique described in Patent Document 1, in a cold district where the outside air is low, the flow rate of the refrigerant sucked into the compressor decreases as the outside air decreases. There was a problem that both the defrosting ability would decrease.

  The present invention has been made in order to solve the above-described problems, and an object thereof is to provide an air conditioner that can achieve both prevention of a decrease in heating capacity and defrosting capacity, particularly in the case of low outside air. To do.

  In the air conditioner according to the present invention, a compressor, a flow path switching valve, a load side heat exchanger, a load side expansion device, a refrigerant heat exchanger, a heat source side expansion device, and a heat source side heat exchanger are sequentially connected by refrigerant piping. The main circuit, an injection pipe that branches the refrigerant pipe between the refrigerant heat exchanger and the load side throttle device, a bypass throttle device, the refrigerant heat exchanger, the first on-off valve, and the compressor injection The heat source side heat exchanger, the second on-off valve, and the compressor by an injection circuit in which ports are sequentially connected, and a bypass pipe that branches the refrigerant pipe between the flow path switching valve and the load side heat exchanger And a defrosting circuit sequentially connected to each other.

  The air conditioner according to the present invention includes a compressor, a flow path switching valve, a load side heat exchanger, a load side expansion device, a refrigerant heat exchanger, a heat source side expansion device, and a heat source side heat exchanger in order of refrigerant piping. A bypass throttle device, a refrigerant heat exchanger, a first on-off valve, and a compressor using an injection pipe that branches the refrigerant pipe between the connected main circuit, the refrigerant heat exchanger, and the load side throttle device The heat source side heat exchanger, the second on-off valve, and the compressor by an injection circuit in which the injection ports are sequentially connected and a bypass pipe that branches the refrigerant pipe between the compressor and the flow path switching valve. A defrosting circuit connected in sequence is provided.

  Since the air conditioning apparatus according to the present invention includes the injection circuit and the defrosting circuit, the use of the injection circuit and the defrosting circuit makes it possible to achieve both the heating capacity and the prevention of the defrosting capacity from being lowered.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
Embodiment 1 FIG.
FIG. 1 is a refrigerant circuit diagram illustrating a refrigerant circuit configuration of an air-conditioning apparatus 100 according to Embodiment 1 of the present invention. Based on FIG. 1, the circuit configuration of the air conditioning apparatus 100 will be described. The air conditioner 100 performs a cooling operation and a heating operation using a refrigeration cycle (heat pump cycle) for circulating a refrigerant. In addition, in the following drawings including FIG. 1, the relationship of the size of each component may be different from the actual one.

  The air conditioner 100 is roughly composed of a heat source side unit (outdoor unit) 10 and a load side unit (indoor unit) 50. The heat source side unit 10 and the load side unit 50 are connected and communicated by a liquid pipe 1 that is a refrigerant pipe and a gas pipe 2 that is a refrigerant pipe. The air conditioner 100 includes a compressor 11, a four-way valve 13 as a flow path switching valve, a load side heat exchanger 52, a load side expansion device 51, a refrigerant heat exchanger 16, a heat source side expansion device 15, and a heat source side exchanger 14. The main circuit is a refrigerant circuit in which the liquid pipe 1 and the gas pipe 2 are sequentially connected. That is, the air conditioner 100 can perform the cooling operation and the heating operation by circulating the refrigerant in the main circuit.

  The heat source unit 10 includes a main refrigerant circuit, an injection circuit, and a defrost circuit. In the main refrigerant circuit, a compressor 11, an oil separation device 12, a four-way valve 13, a heat source side heat exchanger 14, a heat source side expansion device 15, a refrigerant heat exchanger 16, and an accumulator 18 are sequentially connected. It is configured. The compressor 11 sucks the refrigerant flowing through the liquid pipe 1 and compresses the refrigerant to be in a high temperature / high pressure state. For example, the compressor 11 is configured to have a type in which the rotation speed is controlled by an inverter and the capacity is controlled. Good. Further, the compressor 11 has a structure capable of injecting (injecting) refrigerant supplied from an injection circuit into a compression chamber inside the compressor 11.

  The oil separation device 12 has a function of separating the refrigerator oil component from the refrigerant gas in which the refrigerator oil is mixed. The separated refrigerating machine oil is returned to the compressor 11 by controlling the flow rate by the capillary tube 17 provided in the refrigerant pipe connecting the oil separator 12 and the suction side pipe connected to the compressor 11. It has become. The four-way valve 13 switches the refrigerant flow between the cooling operation and the heating operation.

  The heat source side heat exchanger 14 functions as a condenser during cooling operation and as an evaporator during heating operation, and performs heat exchange between air supplied from a fan (not shown) and the refrigerant and converts the refrigerant into evaporated gas or Condensed liquid. The heat source side expansion device 15 functions as a pressure reducing valve or an expansion valve, and decompresses the refrigerant to expand it. It is assumed that the heat source side expansion device 15 is configured by a device whose opening degree can be variably controlled, for example, an electronic expansion valve or the like. The refrigerant heat exchanger 16 exchanges heat between the refrigerant flowing through the main refrigerant circuit and the refrigerant flowing through the injection circuit. The accumulator 18 stores excess refrigerant.

  The injection circuit is configured by connecting an injection pipe 20 that branches the liquid pipe 1 between the refrigerant heat exchanger 16 and the load side expansion device 51 of the load side unit 50 to an injection port of the compressor 11. . Further, the injection pipe 20 between the portion branched from the liquid pipe 1 and the refrigerant heat exchanger 16 is provided with a bypass expansion device 21. This injection pipe 20 is further branched between the refrigerant heat exchanger 16 and the compressor 11, one is connected to the accumulator 18 via the on-off valve 22, and the other is connected via the on-off valve 23 which is the first on-off valve. And connected to the injection port of the compressor 11.

  The bypass throttling device 21 functions as a pressure reducing valve and an expansion valve, and decompresses the refrigerant to expand it. The bypass throttling device 21 is assumed to be configured by a device whose opening degree can be variably controlled, for example, an electronic expansion valve. That is, by flowing a part of the refrigerant flowing through the main refrigerant circuit into the injection circuit, in the refrigerant heat exchanger 16, the refrigerant flowing through the main refrigerant circuit (liquid pipe 1) and the injection pipe 20 flow through the bypass throttling device 21. Heat is exchanged with the refrigerant that has been depressurized and lowered in temperature.

  The on-off valve 22 has a function of being controlled by the control means 40 so that the refrigerant is not conducted. The on-off valve 22 is installed so as to adjust the pressure to prevent liquid sealing (abnormal rise in pressure) in the refrigeration cycle by being controlled by the control means 40. The on-off valve 23 also has a function of being controlled by the control means 40 so that the refrigerant is not conducted. That is, by opening the on-off valve 23, the refrigerant is conducted to the injection pipe 20 to form an injection circuit.

  The defrosting circuit is configured so that the bypass pipe 30 branched from the gas pipe 2 between the four-way valve 13 and the load-side heat exchanger 52 of the load-side unit 50 passes through the heat source-side heat exchanger 14 and then the second defrosting circuit. It is configured by connecting to the suction side of the accumulator 18 via an on-off valve 31 that is an on-off valve. The on-off valve 31 is controlled to open / close, and may or may not conduct refrigerant. In addition, this bypass pipe | tube 30 is guide | induced to the lower part of the heat source side heat exchanger 14 so that the defrosting of the heat source side heat exchanger 14 can be performed efficiently.

  The control means 40 has a function of comprehensively controlling the entire air conditioner 100. Specifically, the control means 40 controls the drive frequency of the compressor 11, the opening degree of the heat source side expansion device 15, the bypass expansion device 21 and the load side expansion device 51, the opening / closing valve 22, the opening / closing valve 23. In addition, the opening / closing of the on-off valve 31 is controlled. Here, although the case where the control means 40 is provided in the heat source side unit 10 is described as an example, the present invention is not limited to this. For example, the control means 40 may be provided in the load side unit 50 or may be provided outside the heat source side unit 10 and the load side unit 50.

  Further, a temperature sensor 3 and a pressure sensor 4 are installed in the heat source side unit 10. The temperature sensor 3 is installed between the heat source side heat exchanger 14 and the heat source side expansion device 15, and mainly detects the temperature of the refrigerant that conducts the heat source side heat exchanger 14. The pressure sensor 4 is installed in a discharge side pipe between the compressor 11 and the four-way valve 13 and detects the pressure of the refrigerant discharged from the compressor 11. The temperature information and pressure information detected by the temperature sensor 3 and the pressure sensor 4 are sent to the control means 40. A temperature sensor for detecting the temperature of the refrigerant discharged from the compressor 11, a pressure sensor for detecting the pressure of the refrigerant sucked into the compressor 11, and the injection pipe 20 after heat exchange by the refrigerant heat exchanger 16 A temperature sensor or the like that detects the temperature of the flowing refrigerant may be installed, and such information may be sent to the control means 40.

  A load side expansion device 51 and a load side heat exchanger 52 are mounted on the load side unit 50. The load side throttle device 51 functions as a pressure reducing valve or an expansion valve, and decompresses the refrigerant to expand it. It is assumed that the load side throttle device 51 is configured by a device whose opening degree can be variably controlled, for example, an electronic expansion valve. The load-side heat exchanger 52 functions as an evaporator during the cooling operation and as a condenser during the heating operation, and performs heat exchange between the refrigerant and the air, and evaporates or condenses the refrigerant. In the first embodiment, the case where one load-side unit 50 is mounted on the air-conditioning apparatus 100 is shown as an example, but the present invention is not limited to this, and a plurality of units may be mounted.

  The liquid pipe 1 and the gas pipe 2 are refrigerant pipes that conduct the refrigerant circulating in the refrigeration cycle. The injection pipe 20 and the bypass pipe 30 are also refrigerant pipes that conduct the refrigerant. Control of the drive frequency of the compressor 11, the opening of the heat source side expansion device 15, the bypass expansion device 21 and the load side expansion device 51, and the opening and closing of the on-off valve 22, on-off valve 23 and on-off valve 31 are control means. 40 is supposed to do. That is, the control means 40 controls each device based on information sent from each temperature sensor or each pressure sensor.

The refrigerant | coolant which can be used for the air conditioning apparatus 100 is demonstrated.
Examples of the refrigerant that can be used in the refrigeration cycle of the air conditioner 100 include a non-azeotropic refrigerant mixture, a pseudo-azeotropic refrigerant mixture, and a single refrigerant. Non-azeotropic refrigerant mixture includes R407C (R32 / R125 / R134a) which is an HFC (hydrofluorocarbon) refrigerant. Since this non-azeotropic refrigerant mixture is a mixture of refrigerants having different boiling points, it has a characteristic that the composition ratio of the liquid-phase refrigerant and the gas-phase refrigerant is different. The pseudo azeotropic refrigerant mixture includes R410A (R32 / R125) and R404A (R125 / R143a / R134a) which are HFC refrigerants. This pseudo azeotrope refrigerant has the same characteristic as that of the non-azeotrope refrigerant and has an operating pressure of about 1.6 times that of R22.

  The single refrigerant includes R22, which is an HCFC (hydrochlorofluorocarbon) refrigerant, R134a, which is an HFC refrigerant, and the like. Since this single refrigerant is not a mixture, it has the property of being easy to handle. In addition, carbon dioxide, propane, isobutane, ammonia, etc., which are natural refrigerants, can also be used. R22 represents chlorodifluoromethane, R32 represents difluoromethane, R125 represents pentafluoroethane, R134a represents 1,1,1,2-tetrafluoroethane, and R143a represents 1,1,1-trifluoroethane. ing. Therefore, it is good to use the refrigerant | coolant according to the use and the objective of the air conditioning apparatus 100. FIG.

Here, operation | movement of the air conditioning apparatus 100 is demonstrated.
First, the heating operation when the outside air temperature is relatively high will be described. Based on FIG. 1, the refrigerant | coolant state at the time of the heating operation of the air conditioning apparatus 100 is demonstrated. When the air conditioner 100 starts the heating operation, the compressor 11 is first driven. The high-temperature and high-pressure gas refrigerant discharged from the compressor 11 flows out from the heat source side unit 10 via the oil separator 12 and the four-way valve 13, flows through the gas pipe 2, and loads on the load side in the load side unit 50. The heat exchanger 52 is reached. In the load-side heat exchanger 52, the gas refrigerant is condensed and liquefied while dissipating heat to air or water, and becomes a low-temperature / high-pressure liquid refrigerant. In other words, the heating operation is performed by giving the heat stored in the refrigerant to the air or water on the load side.

  Further, the condensed and liquefied liquid refrigerant is decompressed to an intermediate pressure by the load side expansion device 51, and becomes an intermediate pressure liquid refrigerant or a gas-liquid two-phase refrigerant. This intermediate-pressure liquid refrigerant or gas-liquid two-phase refrigerant flows out of the load side unit 50, flows through the liquid pipe 1, and reaches the heat source side unit 10. Here, since the outside air temperature is relatively high, the refrigerant does not flow into the injection circuit. That is, the bypass throttling device 21 and the on-off valve 23 are controlled to be closed. The on-off valve 22 may be controlled to be opened and closed so as to adjust the pressure in order to prevent liquid sealing (abnormal pressure increase) in the refrigeration cycle.

  In such a state, the refrigerant that has flowed into the heat source side unit 10 passes through the refrigerant heat exchanger 16 and is then depressurized by the heat source side expansion device 15 to become a low-pressure / low-temperature liquid refrigerant or a gas-liquid two-phase refrigerant. This refrigerant is evaporated and gasified into a gas refrigerant by exchanging heat with air in the heat source side heat exchanger 14. That is, the state changes to gas by absorbing heat from the air supplied to the heat source side heat exchanger 14. The gas refrigerant passes through the four-way valve 13 and the accumulator 18 and is then sucked into the compressor 11. In addition, since the refrigerant does not flow into the injection circuit, the refrigerant heat exchanger 16 does not perform heat exchange.

  Next, the heating operation when the outside air temperature is relatively low, that is, when the outside air temperature is −10 ° C. or lower (low outside air) will be described. FIG. 2 is a Mollier diagram (P-H diagram) showing the refrigerant state of the heating operation when the outside air temperature is relatively low. Based on FIG.1 and FIG.2, the refrigerant | coolant state at the time of the heating operation in case the external temperature of the air conditioning apparatus 100 is comparatively low is demonstrated. In FIG. 2, the vertical axis represents the absolute pressure (P) and the horizontal axis represents the specific enthalpy (H). In addition, the refrigerant is in a gas-liquid two-phase state at the portion surrounded by the saturated liquid line and the saturated vapor line, is liquefied on the left side of the saturated liquid line, and is gas on the right side of the saturated vapor line. It represents that it is in a state of becoming. This Mollier diagram shows the state of the R410A refrigerant.

  When the air conditioner 100 starts the heating operation, the compressor 11 is first driven. The high-temperature and high-pressure gas refrigerant (state (a)) discharged from the compressor 11 flows out of the heat source side unit 10 via the oil separator 12 and the four-way valve 13, flows through the gas pipe 2, and is on the load side. The load-side heat exchanger 52 in the unit 50 is reached. In the load-side heat exchanger 52, the gas refrigerant is condensed and liquefied while dissipating heat to air or water, and becomes a low-temperature / high-pressure liquid refrigerant (state (b)). In other words, the heating operation is performed by giving the heat stored in the refrigerant to the air or water on the load side.

  Further, the condensed and liquefied liquid refrigerant is depressurized to an intermediate pressure by the load side expansion device 51, and becomes an intermediate pressure liquid refrigerant or a gas-liquid two-phase refrigerant (state (c)). This intermediate-pressure liquid refrigerant or gas-liquid two-phase refrigerant flows out of the load side unit 50, flows through the liquid pipe 1, and reaches the heat source side unit 10. Here, since the outside air is low, a part of the refrigerant is allowed to flow into the injection circuit. The control means 40 controls the bypass expansion device 21 and the on-off valve 23 to be in an open state, and diverts the refrigerant that has flowed into the heat source unit 10. That is, the refrigerant flowing into the heat source side unit 10 is divided into the main refrigerant circuit and the injection circuit. Note that the on-off valve 22 is preferably controlled to be in a closed state so that the refrigerant is conducted to the injection circuit.

  The refrigerant divided into the main refrigerant circuit is exchanged in the refrigerant heat exchanger 16 with the low-temperature and low-pressure refrigerant (state (g)) that is diverted into the injection circuit and slightly decompressed by the bypass expansion device 21. It is cooled and becomes a low-temperature and high-pressure liquid refrigerant (state (d)). This liquid refrigerant passes through the refrigerant heat exchanger 16 and is then depressurized by the heat source side expansion device 15 to become a low-temperature and low-pressure gas-liquid two-phase refrigerant (state (e)). This gas-liquid two-phase refrigerant exchanges heat with air in the heat source side heat exchanger 14, thereby evaporating gas into a gas refrigerant (state (f)). That is, the state changes to gas by absorbing heat from the air supplied to the heat source side heat exchanger 14. The gas refrigerant passes through the four-way valve 13 and the accumulator 18 and is then sucked into the compressor 11.

  On the other hand, the refrigerant diverted to the injection circuit is decompressed by the bypass throttling device 21 and becomes a low-temperature / low-pressure gas-liquid two-phase refrigerant (state (g)). This gas-liquid two-phase refrigerant flows into the refrigerant heat exchanger 16 and exchanges heat with an intermediate-pressure liquid refrigerant or gas-liquid two-phase refrigerant (state (c)) flowing through the main refrigerant circuit and heated (state ( h)). In other words, the refrigerant flowing through the injection circuit is heat-exchanged with the refrigerant flowing through the main refrigerant circuit by the refrigerant heat exchanger 16 to become a slightly dry refrigerant. Then, this refrigerant is injected into the injection port of the compressor 11 through the on-off valve 23.

  In the compressor 11, the refrigerant sucked through the main refrigerant circuit (state (f)) is compressed and heated to an intermediate pressure (state (i)), and then injected from the injection circuit (state (h)). ). The merged refrigerant is compressed to a high pressure (state (a)) and discharged again after the temperature is slightly lowered (state (j)). In the heating operation when the outside air temperature is relatively low, heat exchange with the outside air has to be performed, so that the evaporation temperature of the refrigerant decreases, and the evaporation pressure (low pressure) decreases accordingly.

  Therefore, in the refrigeration cycle that does not include the injection circuit, the density of the refrigerant sucked into the compressor is lowered, so that the refrigerant flow rate is reduced and the compression ratio is increased. That is, the capacity of the refrigeration cycle is reduced. In contrast, in the refrigeration cycle having the injection circuit as in the air conditioner 100 according to the first embodiment, the intermediate pressure refrigerant (state (g)) is injected during the compression process of the compressor 11. It is possible to increase the refrigerant flow rate (improve the density of the refrigerant). That is, the heating capacity can be maintained even in low outside air without abnormally increasing the discharge temperature from the compressor 11.

  Here, the defrosting operation at the time of low outside air will be described. When the air-conditioning apparatus 100 is in a heating operation, the temperature of the heat source side heat exchanger 14 may decrease, and frost may adhere to the heat source side heat exchanger 14. If the frost adhering to the heat source side heat exchanger 14 is left as it is, the capacity of the refrigeration cycle is lowered. Therefore, in the air conditioning apparatus 100 according to the first embodiment, a defrost circuit is provided to efficiently defrost the heat source side heat exchanger 14. That is, this air conditioner 100 can perform a more effective defrosting operation by utilizing the injection circuit.

  When the temperature information detected by the temperature sensor 3 is equal to or less than a predetermined value set in advance, the control means 40 determines that frost has accumulated on the heat source side heat exchanger 14 and executes the defrosting operation. . That is, the control means 40 switches the four-way valve 13 so as to reverse the refrigerant flow. At this time, the bypass throttling device 21 may be controlled to be opened or closed. The refrigerant discharged from the compressor 11 in this state flows into the heat source side heat exchanger 14 via the four-way valve 13 to dissolve frost and condense.

  The liquefied refrigerant flows through the liquid pipe 1 in the order of the refrigerant heat exchanger 16, the load side expansion device 51, and the load side heat exchanger 52, and then flows through the gas pipe 2 in the order of the four-way valve 13 and the accumulator 18. 11 flows in. That is, the defrosting operation is performed by supplying the high-temperature and high-pressure refrigerant immediately after being discharged from the compressor 11 to the heat source side heat exchanger 14. The end of the defrosting operation is whether the temperature information detected by the temperature sensor 3 is equal to or higher than a predetermined value set in advance, or the pressure information detected by the pressure sensor 4 is higher than a predetermined value set in advance. It may be executed depending on whether or not a predetermined time has elapsed since the start of the defrosting operation. And when the control means 40 judges completion | finish of a defrost operation, it switches and controls the four-way valve 13 so that it may become the flow of the refrigerant | coolant at the time of heating operation.

Next, the effect of the defrosting operation of the air conditioning apparatus 100 will be described.
FIG. 3 is a schematic perspective view of the heat source side heat exchanger 14 as viewed from the front. First, a schematic configuration of the heat source side heat exchanger 14 will be described with reference to FIG. The heat source side heat exchanger 14 is provided with a liquid pipe 1 and a gas pipe 2 which are refrigerant pipes. The liquid pipe 1 and the gas pipe 2 are bent a plurality of times in the heat source side heat exchanger 14 so that the refrigerant conducted inside can efficiently exchange heat with air supplied from a fan (not shown) or the like. is set up.

  In addition, the heat source side heat exchanger 14 is provided with a part of the bypass pipe 30 in the lower part separately from the liquid pipe 1 and the gas pipe 2. This is because frost adhering to the heat source side heat exchanger 14 easily accumulates in the lower part, so that a part of the bypass pipe 30 is installed in the lower part of the heat source side heat exchanger 14 in advance to improve the efficiency of the defrosting operation. It is. In addition, as shown in FIG. 3, in order to install a part of bypass pipe 30 in the lower part of the heat source side heat exchanger 14, the liquid piping 1 and the gas piping 2 are not installed in the part. That is, a part of the bypass pipe 30 is installed below the lowermost liquid pipe 1 and gas pipe 2 installed in the heat source side heat exchanger 14.

  FIG. 4 is a schematic view showing a frosting state of the heat source side heat exchanger 14. Based on FIG. 4, the frost formation state of the heat source side heat exchanger 14 and the effect of the defrosting operation will be described. 4A is a schematic diagram showing a frosting state of the heat source side heat exchanger 14 before the defrosting operation, and FIG. 4B is a frosting state of the heat source side heat exchanger 14 during the defrosting operation. FIG. 4C is a schematic diagram showing a frosting state of the heat source side heat exchanger 14 after the defrosting operation.

  When the air conditioner 100 is performing the heating operation, the liquid pipe 1 and the gas pipe 2 are installed in the heat source side heat exchanger 14 before the defrosting operation, as shown in FIG. Frost 5 adheres to the part corresponding to the place where This is because the temperature of the heat source side heat exchanger 14 decreases. When the outside air temperature is very low, for example, minus 10 ° C. or less, the residual ice 6 formed by freezing of drain is easily deposited on the base 14 a at the bottom of the heat source side heat exchanger 14. If this state is left as it is, the heating capacity of the air conditioner 100 will be reduced.

  Therefore, the air conditioner 100 performs a defrosting operation for removing the frost 5 attached to the heat source side heat exchanger 14. When the defrosting operation is started, as shown in FIG. 4B, the frost 5 adhering to the upper side of the heat source side heat exchanger 14 is melted and becomes a spill state, and the fins of the heat source side heat exchanger 14 are changed. The frost 5 adhering between the lowermost part of the heat source side heat exchanger 14 and the base 14a and the heat source side heat exchanger 14 remains undissolved. At this time, since the temperature of the drain is not high enough to melt the frost 5, it cannot be melted to the remaining ice 6 on the base 14a. In addition, during snowfall, even if a snow hood or the like is installed, snow may enter through the gap between the hoods and accumulate in the lower part of the heat source side heat exchanger 14.

  That is, by simply supplying the high-temperature and high-pressure refrigerant (hot gas) discharged from the compressor 11 to the heat source side heat exchanger 14, the frost 5 adhering to the heat source side heat exchanger 14 is completely dissolved. It is not possible. Therefore, as shown in FIG. 4C, the air conditioner 100 terminates the defrosting operation and restarts the heating operation, and then heats the high-temperature / high-pressure refrigerant through the bypass pipe 30. By supplying to the lower part of the exchanger 14, the frost 5 at the lower part of the heat source side heat exchanger 14 and the residual ice 6 on the base 14a are melted.

  Specifically, when the defrosting operation is terminated and the heating operation is restarted, the control unit 40 controls the on-off valve 23 to be closed, the on-off valve 22 to be opened, and the bypass expansion device 21 to be opened. To cause the refrigerant to flow into the injection circuit. Then, the control means 40 utilizes the fact that the high pressure of the refrigerant discharged from the compressor 11 rises quickly (and the high pressure reached) is high, or the timing that is early after the defrost operation is completed (or the defrost operation is completed). At the same timing), the on-off valve 31 is controlled to be opened.

  By opening the on-off valve 31, the refrigerant flows into the bypass pipe 30, and the refrigerant circulates through the defrost circuit. Therefore, the high-temperature and high-pressure gas refrigerant discharged from the compressor 11 is supplied to the lower part of the heat source side heat exchanger 14 via the bypass pipe 30, so that the frost 5 attached to the lower part of the heat source side heat exchanger 14. In addition, the residual ice 6 that is volumed on the base 14a can be effectively dissolved. Further, by using the injection circuit, the refrigerant whose temperature has been rapidly raised can be circulated through the bypass pipe 30, so that the drain formed by melting the residual ice 6 is frozen in the base 14 a. The remaining ice 6 can be melted. Thus, the remaining ice 6 accumulated in the lower part of the heat source side heat exchanger 14 can be effectively melted without reducing the efficiency of the heating operation.

  In an air conditioner that does not have an injection circuit, the on-off valve installed in the defrosting circuit because the rise in the high pressure of the refrigerant discharged from the compressor is slow (and the high pressure reached is low). When the opening control is performed, the flow rate of the refrigerant flowing into the load side unit is reduced. In such an air conditioner, when the defrosting operation is performed, the heating capacity is lowered and the defrosting capacity is also lowered. However, the air-conditioning apparatus 100 according to Embodiment 1 can supplement the amount greater than the flow rate of the refrigerant flowing into the defrosting operation with the injection circuit.

  In the defrosting operation of the air conditioner that does not have the injection circuit, the refrigerant circulates through the main circuit. This is because the refrigerant flow in the defrosting operation is the same as that in the cooling operation. In particular, when heating operation is performed with low outside air, the air supplied to the heat source side heat exchanger is low, and the evaporation temperature is lowered accordingly, and the low-temperature and low-pressure gas-liquid two-phase refrigerant is sufficiently vaporized. Since it becomes impossible, the liquid back | bag to a compressor may generate | occur | produce. In order to reduce the liquid back, it is necessary to mount a large accumulator.

  When such a liquid bag occurs, the liquid refrigerant is dissolved in the refrigeration oil, and the content of the refrigeration oil in the refrigerant sucked into the compressor is reduced. As a result, sufficient refrigeration oil is not supplied to the compression mechanism of the compressor, and the starting failure of the compressor and the breakage of the compressor are likely to occur. Moreover, a large accumulator must be mounted, and the heat source side unit must be enlarged. Therefore, the air conditioner 100 according to the first embodiment can adjust the flow rate of the refrigerant flowing into the accumulator 18 by controlling the opening and closing of the bypass expansion device 21 during the defrosting operation. is there. Therefore, the accumulator 18 can be downsized. Moreover, even if the liquid pipe 1 and the gas pipe 2 are long, the occurrence of liquid back can be reduced.

  The opening / closing valve 31 is controlled to be opened at a relatively early timing after the completion of the defrosting operation and after the resumption of the heating operation or at the same timing as the completion of the defrosting operation. The heat source side heat exchanger 14 may be between the heat source side heat exchanger 14 and the heat source side heat exchanger 14 being clogged with the frost 5. This is because at this timing, the influence of the performance degradation of the load-side heat exchanger 52 is small. That is, when the temperature information detected by the temperature sensor 3 is equal to or lower than a predetermined value set in advance or periodically, the on-off valve 31 is controlled to be opened so that the refrigerant is conducted to the defrosting circuit. For example, the clogging of the heat source side heat exchanger 14 and the root ice (residual ice 6) in the lower part can be melted before the defrosting operation. As described above, the air-conditioning apparatus 100 according to Embodiment 1 can achieve both prevention of a decrease in heating capacity and defrosting capacity by using the injection circuit and the defrosting circuit. The on-off valve 31 is closed after a certain period of time has elapsed.

  When the number of operating load-side heat exchangers 52 is increased, the drive frequency of the compressor 11 is controlled to increase according to the total capacity of the load-side heat exchanger 52 and the bypass expansion device 21 is opened. It is good to control to increase the degree. By controlling in this way, the flow rate of the refrigerant discharged from the compressor 11 can be changed according to the total capacity of the load-side heat exchanger 52, and the high pressure can be properly maintained. That is, maintaining the high pressure of the refrigerant leads to maintenance of the condensation temperature, so that the condensation temperature becomes constant and the heating capacity is stabilized even if the number of operating load-side heat exchangers 52 changes.

  On the other hand, when the number of operating load-side heat exchangers 52 is decreased, the drive frequency of the compressor 11 is controlled to be lowered according to the total capacity of the load-side heat exchanger 52 and the bypass expansion device 21 is opened. It is good to control so that a degree may be made small. By controlling in this way, the flow rate of the refrigerant discharged from the compressor 11 can be changed according to the total capacity of the load-side heat exchanger 52, and the high pressure can be properly maintained. That is, maintaining the high pressure of the refrigerant leads to maintenance of the condensation temperature, so that the condensation temperature becomes constant and the heating capacity is stabilized even if the number of operating load-side heat exchangers 52 changes.

Embodiment 2. FIG.
FIG. 5 is a refrigerant circuit diagram illustrating a refrigerant circuit configuration of the air-conditioning apparatus 200 according to Embodiment 2 of the present invention. Based on FIG. 5, the circuit configuration of the air conditioning apparatus 200 will be described. The air conditioner 200 performs a cooling operation and a heating operation using a refrigeration cycle (heat pump cycle) for circulating a refrigerant. In the second embodiment, differences from the first embodiment will be mainly described, and the same parts as those in the first embodiment will be denoted by the same reference numerals and the description thereof will be omitted.

  The air conditioning apparatus 200 is different from the air conditioning apparatus 100 according to Embodiment 1 in the defrosting circuit. That is, the defrosting circuit of the air conditioner 200 branches the gas pipe 2 between the oil separator 12 and the four-way valve 13, connects one to the four-way valve 13, and connects the other bypass pipe 30 ′ to the heat source side. After passing through the heat exchanger 14, the heat exchanger 14 is connected to the suction side of the accumulator 18 via the on-off valve 31. That is, the defrosting circuit according to the first embodiment branches the gas pipe 2 between the four-way valve 13 and the load side unit 50, but the defrosting circuit according to the second embodiment includes the oil separator 12 and The gas pipe 2 is branched from the four-way valve 13.

  Even if the air conditioner 200 has such a configuration, the same effect as the air conditioner 100 according to Embodiment 1 can be obtained. Therefore, the air conditioning apparatus 200 according to Embodiment 2 can increase the refrigerant flow rate (improve the refrigerant density) without abnormally increasing the temperature of the refrigerant discharged from the compressor 11 by providing an injection circuit. The heating capacity can be maintained even with low outside air. In addition, after the defrosting operation is completed, the air conditioner 200 supplies a refrigerant having a high pressure increase rate and a high reachability to the heat source side heat exchanger 14 via the defrosting circuit by the injection circuit. Thus, the frost attached to the heat source side heat exchanger 14 can be more effectively defrosted.

  The air conditioning apparatus 100 and the air conditioning apparatus 200 can be applied to a refrigeration apparatus, a room air conditioner, a packaged air conditioner, a refrigerator, a humidifier, a humidity control apparatus, a heat pump water heater, and the like. Therefore, the refrigerant to be used, the number of load-side units 50, the number of temperature sensors, and the number of pressure sensors may be determined according to the purpose and application of the air-conditioning apparatus 100 and the air-conditioning apparatus 200. Moreover, the control means 40 is good to comprise with the microcomputer etc. which can control the air conditioning apparatus 100 and the air conditioning apparatus 200 whole.

3 is a refrigerant circuit diagram illustrating a refrigerant circuit configuration of the air-conditioning apparatus according to Embodiment 1. FIG. It is a Mollier diagram (PH diagram) showing a refrigerant state of heating operation at the time of low outside air. It is a schematic perspective view when the heat source side heat exchanger is viewed from the front. It is the schematic which shows the frost formation state of a heat source side heat exchanger. 6 is a refrigerant circuit diagram illustrating a refrigerant circuit configuration of an air-conditioning apparatus according to Embodiment 2. FIG.

Explanation of symbols

  1 liquid piping, 2 gas piping, 3 temperature sensor, 4 pressure sensor, 5 frost, 6 remaining ice, 10 heat source side unit, 11 compressor, 12 oil separator, 13 four-way valve, 14 heat source side heat exchanger, 14a base , 15 Heat source side throttle device, 16 Refrigerant heat exchanger, 17 Capillary tube, 18 Accumulator, 20 Injection tube, 21 Bypass throttle device, 22 Open / close valve, 23 Open / close valve (first open / close valve), 30 Bypass tube, 30 ′ bypass Pipe, 31 on-off valve (second on-off valve), 40 control means, 50 load-side unit, 51 load-side expansion device, 52 load-side heat exchanger, 100 air conditioner, 200 air conditioner.

Claims (6)

A main circuit in which a compressor, a flow path switching valve, a load side heat exchanger, a load side expansion device, a refrigerant heat exchanger, a heat source side expansion device, and a heat source side heat exchanger are sequentially connected by refrigerant piping;
The bypass throttle device, the refrigerant heat exchanger, the first on-off valve, and the injection port of the compressor are sequentially connected by an injection pipe branched from the refrigerant pipe between the refrigerant heat exchanger and the load side throttle device. Injection circuit,
A defrost circuit in which the heat source side heat exchanger, the second on-off valve, and the compressor are sequentially connected by a bypass pipe that branches the refrigerant pipe between the flow path switching valve and the load side heat exchanger; An air conditioner characterized by comprising. A main circuit in which a compressor, a flow path switching valve, a load side heat exchanger, a load side expansion device, a refrigerant heat exchanger, a heat source side expansion device, and a heat source side heat exchanger are sequentially connected by refrigerant piping;
The bypass throttle device, the refrigerant heat exchanger, the first on-off valve, and the injection port of the compressor are sequentially connected by an injection pipe branched from the refrigerant pipe between the refrigerant heat exchanger and the load side throttle device. Injection circuit,
A defrost circuit in which the heat source side heat exchanger, the second on-off valve, and the compressor are sequentially connected by a bypass pipe that branches the refrigerant pipe between the compressor and the flow path switching valve. An air conditioner characterized by. 3. The air conditioner according to claim 1, wherein a part of the bypass pipe is installed to be lower than the lowermost refrigerant pipe installed in the heat source side heat exchanger. A temperature sensor for detecting the temperature of the heat source side heat exchanger;
When the temperature information from the temperature sensor is equal to or lower than a predetermined value set in advance, the defrosting is performed by switching the flow path switching valve and supplying the refrigerant discharged from the compressor to the heat source side heat exchanger. Control means for starting operation,
The control means includes
When the temperature information from the temperature sensor is equal to or higher than a predetermined value set in advance, the defrosting operation is terminated, the first on-off valve and the bypass throttling device are controlled to be opened, and the refrigerant is conducted to the injection pipe. The air conditioner according to any one of claims 1 to 3, wherein the second on-off valve is controlled to be in an open state and the refrigerant is conducted to the bypass pipe. The control means includes
The control for opening the first on-off valve and the bypass throttling device and the control for opening the second on-off valve are performed immediately after the defrosting operation is completed, or in the defrosting operation. The air conditioner according to claim 4, wherein the air conditioner is executed simultaneously with the termination. The control means includes
Control for opening the first on-off valve and bypass throttling device, and control for opening the second on-off valve, and temperature information from the temperature sensor is below a predetermined value set in advance The air conditioner according to claim 4, wherein the air conditioner is executed at regular intervals or periodically.

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