Air conditioner

Abstract

An air conditioner, according to one embodiment of the present disclosure, comprises: an outdoor unit including a compressor, an accumulator connected to the compressor, a suction flow path via which refrigerant discharged from the accumulator is supplied to the compressor, a discharge flow path through which the refrigerant is discharged from the compressor, an outdoor heat exchanger exchanging heat between the refrigerant flowing via the compressor and outside air, and a switching valve for switching the outdoor heat exchanger to a condenser or an evaporator; and a plurality of indoor units connected to the outdoor unit and having indoor heat exchangers, the switching valve including a first switching valve connected to the outdoor heat exchanger via an outdoor heat exchanger connection pipe and a second switching valve connected to the first switching valve via a connection flow path, wherein when a cooling cycle is terminated, the first switching valve maintains a state thereof, the second switching valve is switched, and after a preset reference time has elapsed, the air conditioner is switched to a heating cycle.

Description

air conditioner

[0001] The present disclosure relates to an air conditioner, and more specifically, to an air conditioner capable of cooling and heating operation.

[0002] An air conditioner is installed to provide a more comfortable indoor environment for humans by discharging hot and cold air into the room to regulate the indoor temperature and purify the indoor air, thereby creating a pleasant indoor environment. Generally, an air conditioner includes an indoor unit composed of a heat exchanger and installed indoors, and an outdoor unit composed of a compressor and a heat exchanger, which supplies refrigerant to the indoor unit.

[0003] The air conditioner operates in cooling or heating mode depending on the flow of the refrigerant.

[0004] During cooling operation, high-temperature, high-pressure liquid refrigerant is supplied from the outdoor unit's compressor through the outdoor unit's heat exchanger to the indoor unit; as the refrigerant expands and vaporizes in the indoor unit's heat exchanger, the temperature of the surrounding air decreases, and as the indoor unit's fan rotates, cold air is discharged into the room.

[0005] During heating operation, high-temperature, high-pressure gaseous refrigerant is supplied to the indoor unit from the outdoor unit's compressor, and air warmed by the energy released as the high-temperature, high-pressure gaseous refrigerant liquefies in the indoor unit's heat exchanger is discharged into the room according to the operation of the indoor unit's fan.

[0006] Combined heating and cooling air conditioners switch the direction of refrigerant flow using valves. For example, the outdoor heat exchanger is switched from the condenser to the evaporator through the switching of a four-way valve.

[0007] Korean Patent No. 10-1081056 relates to a heating and cooling combined air conditioner and a four-way valve control method. When stopping the system after heating operation, the four-way valve shut-off time is automatically adjusted according to the pressure (or temperature) difference between the compressor inlet and outlet, thereby minimizing noise caused by the shut-off of the four-way valve.

[0008] The condenser is a heat exchanger containing a large amount of liquid refrigerant, and most of the system's refrigerant is concentrated on the condenser side. At this time, as the outdoor heat exchanger, which was at a relatively high pressure (condenser), is connected to the low-pressure line, an excessive amount of liquid refrigerant may flow into the low-pressure line. Therefore, it is necessary to prevent liquid refrigerant from flowing into the compressor when switching the operating cycle.

[0009] Meanwhile, the air conditioner can be connected to an outdoor unit and multiple indoor units. Depending on the connection method between the multiple indoor units and the outdoor unit, it can be used as a switching type air conditioner or a simultaneous type air conditioner.

[0010] Switching type air conditioners can operate all indoor units in either cooling or heating mode simultaneously, whereas simultaneous type air conditioners can operate some indoor units in cooling mode and others in heating mode at the same time.

[0011] A simultaneous air conditioner is configured such that a single outdoor unit is connected to multiple indoor units via three refrigerant pipes, allowing each of the multiple indoor units to simultaneously perform cooling and heating operations. To achieve this, the simultaneous air conditioner places a distributor between the outdoor unit and the indoor unit, and provides condensed refrigerant to the indoor unit of a room requiring cooling to cool the room, and provides compressed refrigerant to the indoor unit of a room requiring heating to heat the room.

[0012]

[0013] The problem that the present disclosure aims to solve is to provide an air conditioner capable of preventing liquid refrigerant from entering the compressor.

[0014] Another objective of the present disclosure is to provide an air conditioner capable of cooling and heating operations.

[0015] Another objective of the present disclosure is to provide an air conditioner capable of preventing liquid refrigerant inflow when switching from a cooling cycle to a heating cycle.

[0016] Another objective of the present disclosure is to provide an air conditioner capable of preventing compressor failure.

[0017] Another objective of the present disclosure is to provide an outdoor unit that can be used for both simultaneous and switching types.

[0018] The problems of the present disclosure are not limited to those mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the description below.

[0019] To achieve the above objective, an air conditioner according to one embodiment of the present disclosure is equipped with two switching valves and can prevent liquid refrigerant from entering the compressor by controlling the switching valves in stages.

[0020] An air conditioner according to one embodiment of the present disclosure comprises: a compressor; an accumulator connected to the compressor; a suction path through which refrigerant discharged from the accumulator is supplied to the compressor; a discharge path through which refrigerant is discharged from the compressor; an outdoor heat exchanger that exchanges heat between the refrigerant flowing through the compressor and external air; an outdoor unit comprising a switching valve that switches the outdoor heat exchanger to a condenser or an evaporator; and a plurality of indoor units connected to the outdoor unit and equipped with an indoor heat exchanger.

[0021] The switching valve comprises a first switching valve connected to the outdoor heat exchanger via an outdoor heat exchanger connection pipe, and a second switching valve connected to the first switching valve via a connecting passage.

[0022] When the cooling cycle ends, the first switching valve maintains its state, switches the second switching valve, and switches to the heating cycle after a preset reference time has elapsed.

[0023] The above outdoor unit and the above plurality of indoor units are connected by a first pipe and a second pipe, the first pipe connects the outdoor heat exchanger and the indoor heat exchanger, and the second pipe can connect the indoor heat exchanger and the switching valve.

[0024] The first switching valve is connected to the outdoor heat exchanger connecting pipe and the second pipe, and the second switching valve can be connected to the second pipe and the connecting path.

[0025] After the above reference time has elapsed, the first switching valve can be switched, and the second switching valve can maintain its state.

[0026] The above outdoor unit may further include an outdoor expansion valve disposed in the first pipe.

[0027] During the above cooling cycle, the first switching valve may be in an off state and the second switching valve may be in an on state.

[0028] When the above cooling cycle ends, the second switching valve can be switched to an off state.

[0029] After the above reference time has elapsed, the first switching valve can be switched to the ON state.

[0030] A third pipe is further connected to the above outdoor unit and the above plurality of indoor units, and the third pipe may be connected to the first switching valve, the second switching valve, and the accumulator. After the above reference time has elapsed, the first switching valve and the second switching valve may be switched.

[0031] The first switching valve is connected to the outdoor heat exchanger connecting pipe, the second pipe, and the third pipe, and the second switching valve can be connected to the second pipe, the connecting passage, and the third pipe.

[0032] During the above cooling cycle, the first switching valve is in an off state and the second switching valve is in an on state, and when the cooling cycle ends, the second switching valve is switched to an off state, and after the above reference time has elapsed, the first switching valve and the second switching valve can be switched to an on state.

[0033] An air conditioner according to one embodiment of the present disclosure may further include a distributor disposed between the outdoor unit and the plurality of indoor units and connected to the first pipe, the second pipe, and the third pipe.

[0034] Depending on the type of the plurality of indoor units, the control of the first switching valve and the second switching valve when switching to the heating cycle may differ.

[0035] Depending on whether the above-mentioned third pipe is used, the control of the above-mentioned first switching valve and the above-mentioned second switching valve when switching to the above-mentioned heating cycle may differ.

[0036] The above reference time may correspond to at least one of the capacity of the air conditioner, the length of the internal pipes, and the internal volume.

[0037] The above cooling cycle may be a cooling operation, a defrosting operation, or an oil recovery operation.

[0038] According to at least one of the embodiments of the present disclosure, liquid refrigerant inflow into the compressor can be prevented, thereby preventing compressor failure.

[0039] According to at least one of the embodiments of the present disclosure, cooling and heating functions can be reliably provided.

[0040] According to at least one of the embodiments of the present disclosure, when switching from a cooling cycle to a heating cycle, the inflow of liquid refrigerant can be effectively prevented.

[0041] According to at least one of the embodiments of the present disclosure, the same outdoor unit can be used in both simultaneous and switching modes depending on the piping connection, thereby reducing costs.

[0042] According to at least one of the embodiments of the present disclosure, the refrigerant flow can be stably controlled depending on the type of air conditioner.

[0043] Meanwhile, various other effects will be disclosed directly or implicitly in the detailed description according to the embodiments of the present disclosure to be described below.

[0044] FIG. 1 is a schematic diagram of an air conditioner system according to one embodiment of the present disclosure.

[0045] FIG. 2 is a schematic diagram of an air conditioner system according to one embodiment of the present disclosure.

[0046] Figure 3 is a drawing referenced in the description of the heating cycle in the system of Figure 1.

[0047] Figure 4 is a drawing referenced in the description of the cooling cycle in the system of Figure 1.

[0048] Figure 5 is a diagram illustrating a cooling cycle pH diagram.

[0049] FIGS. 6a to 6c are drawings referenced in the description of switching valve control according to one embodiment of the present disclosure.

[0050] FIG. 7 is a flowchart illustrating the operation method of an air conditioner according to one embodiment of the present disclosure.

[0051] Figure 8 is a drawing referenced in the description of the heating cycle in the system of Figure 2.

[0052] Figure 9 is a drawing referenced in the description of the cooling cycle in the system of Figure 2.

[0053] FIGS. 10a to 10c are drawings referenced in the description of switching valve control according to one embodiment of the present disclosure.

[0054] FIG. 11 is a flowchart illustrating the operation method of an air conditioner according to one embodiment of the present disclosure.

[0055] FIG. 12 is a flowchart illustrating the operation method of an air conditioner according to one embodiment of the present disclosure.

[0056] Hereinafter, embodiments disclosed in this specification will be described in detail with reference to the attached drawings. Identical or similar components are given the same reference numeral regardless of drawing symbols, and redundant descriptions thereof will be omitted.

[0057] Terms including ordinal numbers, such as first, second, etc., may be used to describe various components, but said components are not limited by said terms. These terms are used solely for the purpose of distinguishing one component from another.

[0058] When it is stated that one component is “connected” or “connected” to another component, it should be understood that while it may be directly connected or connected to that other component, there may also be other components in between. On the other hand, when it is stated that one component is “directly connected” or “directly connected” to another component, it should be understood that there are no other components in between.

[0059] FIGS. 1 and FIGS. 2 are schematic diagrams of an air conditioner system according to an embodiment of the present disclosure.

[0060] Referring to FIG. 1 and FIG. 2, an air conditioner according to an embodiment of the present disclosure includes an outdoor unit (20) and a plurality of indoor units (10) connected to the outdoor unit (20).

[0061] The outdoor unit (20) includes a compressor (122) and an outdoor heat exchanger (124) that exchanges heat between the refrigerant flowing through the compressor (122) and the outside air.

[0062] Each of the plurality of indoor units (10) may include an indoor heat exchanger (112) that exchanges heat between the air supplied to the indoor unit and the refrigerant, and an indoor expansion valve (114) that expands the refrigerant flowing into the indoor heat exchanger (112).

[0063] The outdoor unit (20) can be used for both simultaneous and switching types. The outdoor unit (20) can be installed as a switching type or a simultaneous type. Accordingly, the manufacturing cost and installation cost of the air conditioner can be reduced.

[0064] The outdoor unit (20) can be configured as a switching air conditioner system or a simultaneous air conditioner system depending on the indoor unit and pipe connection.

[0065] FIG. 1 illustrates a switching type air conditioner, and FIG. 2 illustrates a simultaneous type air conditioner.

[0066] Referring to FIG. 1, a plurality of indoor units (10) are equipped with an indoor heat exchanger (112) and are connected to the outdoor unit (20) by a plurality of pipes (2, 4). A service valve (2a, 4a) for opening and closing the pipe (2, 4) may be provided in each pipe (2, 4).

[0067] Referring to FIG. 1, the outdoor unit (20) and the plurality of indoor units (10) can be connected by a first pipe (2) and a second pipe (4). The first pipe (2) can connect an outdoor heat exchanger (124) and an indoor heat exchanger (112). The second pipe (4) can connect an indoor heat exchanger (112) and a switching valve (120).

[0068] Referring to FIG. 2, a plurality of indoor units (10) are equipped with an indoor heat exchanger (112) and are connected to the outdoor unit (20) by a plurality of pipes (2, 4, 6). A service valve (2a, 4a, 6a) for opening and closing the pipe (2, 4, 6) may be provided in each pipe (2, 4, 6).

[0069] The air conditioner includes a switching valve (120) that sends the refrigerant discharged from the compressor (122) to at least one of the outdoor heat exchanger (124) and the indoor heat exchanger (112). The outdoor heat exchanger (124) can be switched to a condenser or an evaporator through the control of the switching valve (120).

[0070] The switching valve (120) includes a first switching valve (128) and a second switching valve (126).

[0071] The first switching valve (128) is connected to the outdoor heat exchanger (124) via an outdoor heat exchanger connecting pipe (138). The second switching valve (126) is connected to the first switching valve (128) via a connecting passage (162).

[0072] The first switching valve (128) can be connected to the outdoor heat exchanger connecting pipe (138) and the second pipe (4). The second switching valve (126) can be connected to the second pipe (4) and the connecting passage (162).

[0073] The first switching valve (128) can send the refrigerant flowing from the outdoor heat exchanger (124) to the compressor (122). The refrigerant flowing from the outdoor heat exchanger (124) can flow into the compressor (122) via the outdoor heat exchanger connecting pipe (138), connecting pipe (136), and accumulator (134).

[0074] In addition, the first switching valve (128) can send the refrigerant discharged from the compressor (122) to the outdoor heat exchanger (124).

[0075] The second pipe (4) can flow high temperature and high pressure refrigerant or low temperature and low pressure refrigerant depending on the operating mode of the indoor unit (10).

[0076] Referring to FIGS. 1 and FIGS. 2, the first pipe (2) is branched and connected to each indoor unit (10). The second pipe (4) is also connected to each indoor unit (10).

[0077] The outdoor unit (20) may include an outdoor expansion valve (130) that expands the refrigerant flowing into or from the outdoor heat exchanger (124). The outdoor expansion valve (130) may be placed in the first pipe (2).

[0078] The first pipe (2) is connected to an outdoor heat exchanger (124), and the outdoor expansion valve (130) may be positioned on the outdoor heat exchanger (124) side of the first pipe (2). Additionally, the first pipe (2) and the outdoor heat exchanger (124) may be connected by a sub-liquid pipe (144), and the outdoor expansion valve (130) may be positioned in the sub-liquid pipe (144).

[0079] The outdoor expansion valve (130) can expand the refrigerant flowing to the outdoor heat exchanger (124) during heating operation, and can pass the refrigerant without expansion during cooling operation. The outdoor expansion valve (130) may be an electronic expansion valve (EEV) capable of adjusting the opening value according to an input signal.

[0080] An outdoor heat exchanger connecting pipe (138) connecting the first switching valve (128) and the outdoor heat exchanger (124) may be provided in the outdoor unit (20).

[0081] The outdoor unit (20) may include an oil separator (not shown) that recovers oil from the refrigerant discharged from the compressor (122). The oil separated from the oil separator may be recovered to the compressor (122) through an oil recovery path (not shown).

[0082] The outdoor unit (20) further includes an accumulator (134) connected to the compressor (122).

[0083] It includes an accumulator (134) that separates the refrigerant flowing to the compressor (122) into gaseous refrigerant and liquid refrigerant, and sends the separated gaseous refrigerant to the compressor (122).

[0084] The suction path (177) can connect the accumulator (134) and the compressor (122).

[0085] The suction path (177) can guide the gaseous refrigerant from the accumulator (134) to the compressor (122). The gaseous refrigerant can be discharged from the accumulator (134) into the suction path (177) and sucked into the compressor (122). The refrigerant discharged from the accumulator (134) can be supplied to the compressor (122) through the suction path (177).

[0086] The compressor (122) can be connected to the accumulator (134). The refrigerant suction path of the compressor (122) can be in communication with the accumulator (134). The compressor (122) can discharge refrigerant through the discharge path (159).

[0087] A compressor (122) or an oil separator may be connected to a discharge passage (159). The discharge passage (159) may be connected to a connecting passage (162). The connecting passage (162) may connect a first switching valve (128) and a second switching valve (126).

[0088] The outdoor unit (20) may include an outdoor fan. The outdoor fan may be positioned to face the outdoor heat exchanger (126). The outdoor fan may perform the function of blowing outside air to the outdoor heat exchanger (126).

[0089] A plurality of temperature sensors may be disposed in the outdoor unit (20). For example, an outdoor heat exchanger temperature sensor may measure the temperature of the outdoor heat exchanger (124). Additionally, an outdoor heat exchanger outlet temperature sensor may be disposed at the outlet side of the outdoor heat exchanger (124) to measure the temperature of the refrigerant condensed in the outdoor heat exchanger (124). Additionally, a plurality of pressure sensors may be disposed in the outdoor unit (20).

[0090] The refrigerant flow is controlled according to the operation of the first switching valve (128) and the second switching valve (126). The first switching valve (128) and the second switching valve (126) can switch the outdoor heat exchanger (124) to a condenser or an evaporator.

[0091] The first switching valve (128) and the second switching valve (126) may be four-way valves. The operation of the first switching valve (128) and the second switching valve (126) can determine the operating mode of the outdoor heat exchanger (124).

[0092] The specific operation of the switching type air conditioner will be described later with reference to FIGS. 3 to 7.

[0093] Referring to FIG. 2, a third pipe (6) may be further connected to the outdoor unit (20) and the plurality of indoor units (10). That is, the outdoor unit (20) and the plurality of indoor units (10) may be connected by the first to third pipes (2, 4, 6).

[0094] The simultaneous air conditioner uses not only the first pipe (2) and the second pipe (4) but also the third pipe (6). The third pipe (6) can be connected to the first switching valve (128), the second switching valve (126), and the accumulator (134).

[0095] The first switching valve (128) can be connected to the outdoor heat exchanger connection pipe (138), the second pipe (4), and the third pipe (6). The second switching valve (126) can be connected to the second pipe (4), the connecting passage (162), and the third pipe (6).

[0096] According to an embodiment, the first pipe (2) may be a liquid pipe through which liquid refrigerant flows. The second pipe (4) may be a high-pressure pipe through which high-temperature, high-pressure hot gas discharged from the compressor (122) passes. The third pipe (6) may be a low-pressure pipe for low-temperature, low-pressure.

[0097] Referring to FIG. 2, the apparatus may further include a distributor (40) that is positioned between the outdoor unit (20) and the plurality of indoor units (10) and is connected to the first pipe (2), the second pipe (4), and the third pipe (6).

[0098] The distributor (40) can be connected independently to each indoor unit (10). For example, the distributor (40) can be connected to each indoor unit (10) via two pipes in the section after the output. Alternatively, the distributor (40) can be equipped with valves for each indoor unit / pipe inside to control the refrigerant flow and can be connected to each indoor unit (10) via one pipe.

[0099] Heat recovery operation can be performed by installing a distributor (40) between an outdoor unit (20) and a plurality of indoor units (10). Since the distributor (40) controls the flow and distribution of refrigerant, high-efficiency heat recovery operation is possible. Recently, simultaneous air conditioners are also implemented without a distributor (40).

[0100] The distributor (40) can send refrigerant discharged from the outdoor unit (20) to a plurality of indoor units (10). The distributor (40) can send refrigerant flowing from the plurality of indoor units (10) to the outdoor unit (20). The distributor (40) can send refrigerant flowing from some of the indoor units to other indoor units among the plurality of indoor units. The distributor (40) enables each of the plurality of indoor units (10) to perform different operations.

[0101] The specific operation of the simultaneous air conditioner will be described later with reference to FIGS. 8 to 11.

[0102] An air conditioner according to the present disclosure can operate in a heating cycle or a cooling cycle, wherein the refrigerant flow is controlled by switching of the switching valve (120). The refrigerant flow direction in the heating cycle and the cooling cycle may be opposite.

[0103] The cooling / heating cycle can correspond to the operating mode of the air conditioner. The cooling cycle may include general cooling operation, defrosting operation, and oil recovery operation. The cooling cycle may be cooling operation, defrosting operation, or oil recovery operation, and the heating cycle may be heating operation.

[0104] Compressor liquid ingress may occur when switching between the cooling and heating cycles, such as during defrosting, oil recovery, and cooling-heating mode switching operations.

[0105] According to an embodiment of the present disclosure, the high-low pressure difference can be sequentially reduced through a two-stage switching process without immediately switching the switching valve (120) to suit each operating mode.

[0106] In particular, when switching from a cooling cycle to a heating cycle, liquid inflow into the compressor can be prevented by sequentially reducing the difference between high and low pressures.

[0107] Previously, when switching modes, the high-pressure side line of the cooling cycle (outdoor heat exchanger (124)) was directly connected to the accumulator (134) and compressor (122), so that the refrigerant on the high-pressure side flowed into the low-pressure side in an instant.

[0108] However, according to an embodiment of the present disclosure, by gradually reducing the difference between high and low pressures, the amount of refrigerant flowing from the high-pressure side to the low-pressure side can be reduced.

[0109] By adding separate piping and valves to the accumulator (134) and compressor (122), the difference between high and low pressure can be reduced. In this case, if the system is large and the connecting pipe is long, the effect of reducing the differential pressure on the heat exchanger side is not significant. Additionally, if the differential pressure is not properly reduced, high-pressure refrigerant on the heat exchanger side may flow into the accumulator (134) when switching modes, causing liquid inflow into the compressor.

[0110] However, the present disclosure can effectively reduce the high-low pressure difference and prevent compressor liquid inflow by only sequential step control of the switching valve (120).

[0111] Hereinafter, with reference to the drawings, the control of an air conditioner and a switching valve (120) according to an embodiment of the present disclosure will be described in detail.

[0112] Figure 3 is a drawing referenced in the description of the heating cycle in the system of Figure 1.

[0113] Referring to FIG. 3, in the heating cycle, the first switching valve (128) is controlled to the ON state and the second switching valve (126) is controlled to the OFF state. Accordingly, the refrigerant discharged from the compressor (122) flows to the indoor heat exchanger (112).

[0114] The refrigerant discharged from the compressor (122) passes through the discharge path (159), the first switching valve (128), the second switching valve (126), and the second pipe (4), and is supplied to the indoor heat exchanger (112) for heat exchange.

[0115] Additionally, the refrigerant passes through an outdoor heat exchanger (124) and is recovered in an accumulator (134) and a compressor (122).

[0116] Figure 4 is a drawing referenced in the description of the cooling cycle in the system of Figure 1.

[0117] Figure 4 shows a typical reverse cycle defrosting operation (same as cooling operation).

[0118] In the cooling cycle, the first switching valve (128) and the second switching valve (126) are switched on / off so that the outdoor heat exchanger (124) is used as a condenser and the indoor heat exchanger (124) is used as an evaporator.

[0119] However, when performing defrosting operation during the heating season (e.g., winter), the indoor unit (10) fan is operated in an off state to prevent user discomfort caused by cold air.

[0120] Referring to FIG. 4, in the cooling cycle, the first switching valve (128) is controlled to the off state and the second switching valve (126) is controlled to the on state. Accordingly, the refrigerant discharged from the compressor (122) flows to the outdoor heat exchanger (124).

[0121] The refrigerant discharged from the compressor (122) passes through the discharge path (159), the first switching valve (128), and the outdoor heat exchanger connection pipe (138), and is supplied to the outdoor heat exchanger (124) for heat exchange.

[0122] Additionally, the refrigerant passes through the indoor heat exchanger (124), the second pipe (4), and the second switching valve (126), and is recovered in the accumulator (134) and compressor (122).

[0123] When the cooling cycle starts, the outdoor heat exchanger (124) changes from an evaporator to a condenser. The condenser is a heat exchanger with a large amount of liquid refrigerant.

[0124] Figure 5 is a diagram illustrating a cooling cycle pH diagram.

[0125] Referring to FIG. 5, when switching from high pressure to low pressure, the condenser corresponds to a subcooled liquid refrigerant region (510), and the outdoor heat exchanger (124) becomes filled with liquid refrigerant as the refrigerant is condensed.

[0126] Meanwhile, after the cooling cycle, such as defrosting operation, is completed, the first switching valve (128) and the second switching valve (126) can be switched to return to the heating cycle to restart the heating operation.

[0127] In this case, the high-pressure liquid refrigerant in the outdoor heat exchanger (124) can be immediately fed into the low-pressure accumulator (134) as the first switching valve (128) is switched while the pressure of the liquid refrigerant in the outdoor heat exchanger (124) is not lowered.

[0128] When the amount of liquid refrigerant flowing in is large, liquid refrigerant may flow into the compressor (122) even though there is an accumulator (134).

[0129] When the outdoor heat exchanger (124) switches from the condenser to the evaporator, the risk of liquid refrigerant entering the compressor (122) increases. Liquid refrigerant inflow into the compressor is one of the typical causes of compressor failure.

[0130] Controls for switching the outdoor heat exchanger (124) from the condenser to the evaporator include, typically, defrosting operation, oil recovery operation, and cooling / heating switching operation for transitional seasons or simultaneous types of products.

[0131] When switching from the condenser to the evaporator, the greater the pressure difference between the outdoor heat exchanger (124) and the low-pressure line, the greater the amount of refrigerant flowing in.

[0132] According to an embodiment of the present disclosure, the first switching valve (128) and the second switching valve (126) can be controlled in stages so as to reduce the difference between high and low pressure.

[0133] When the cooling cycle ends, the second switching valve (126) is switched first. At this time, the first switching valve (128) maintains its current state.

[0134] During the cooling cycle, the first switching valve (128) is in the off state, and the second switching valve (126) is in the on state.

[0135] Accordingly, when the cooling cycle ends, the second switching valve (126) is switched to the off state in the first stage control, and the first switching valve (128) remains in the off state.

[0136] Stage 1 control is maintained for a preset reference time, and switches to Stage 2 control when the reference time has elapsed.

[0137] The reference time should be set to a sufficient amount of time for the pressure difference to decrease, and may be set differently depending on the air conditioning system.

[0138] The reference time may correspond to at least one of the capacity of the air conditioner, the length of the internal piping, or the internal volume. For example, a model with longer internal piping length may have a longer reference time than a model with shorter internal piping length. Additionally, a model with a smaller internal volume of internal piping may have a shorter reference time than a model with a larger internal volume.

[0139] Meanwhile, after the preset reference time has elapsed, it switches to the heating cycle. If a defrosting operation is performed during heating operation, the defrosting operation is completed, and after the stage control is maintained for the preset reference time, the heating operation is restarted.

[0140] When the preset reference time has elapsed, the system enters 2nd stage control and switches the first switching valve (128). At this time, the second switching valve (126) maintains its current state.

[0141] During the first stage of control, both the first switching valve (128) and the second switching valve (126) are in the off state, so for the second stage of control, the first switching valve (128) is switched to the on state and the second switching valve (126) is kept in the off state.

[0142] According to an embodiment of the present disclosure, the high-low pressure difference is sequentially reduced by switching the first switching valve (128) and the second switching valve (126) in two steps.

[0143] FIGS. 6a to 6c are drawings referenced in the description of switching valve control in a switching type air conditioner according to one embodiment of the present disclosure.

[0144] FIG. 7 is a flowchart illustrating the operation method of an air conditioner according to one embodiment of the present disclosure, and a switching valve control method in a switching type air conditioner is exemplified.

[0145] FIG. 6a illustrates the switching valve (120) and refrigerant flow in a cooling cycle. For example, FIG. 6a illustrates the state of the first switching valve (128) and the second switching valve (126) during defrosting operation.

[0146] Referring to FIG. 7, after the defrosting operation is completed (S710) and before the heating restart (S730), the heating restart of FIG. 6c can be performed after going through the pressure control steps (S720, S730) as in FIG. 6b (S740).

[0147] The normal pressure control step (S720, S730) is performed by switching the second switching valve (126) (S720) and maintaining it for a certain standard time (e.g., about 2 minutes) (S720). In the normal pressure control step, the liquid refrigerant of the outdoor heat exchanger (124) is prevented from flowing directly into the accumulator (134), and some of the refrigerant is allowed to flow into the pipe connected to the indoor unit (10).

[0148] Through this, liquid refrigerant flows into the connecting pipe side and simultaneously the pressure of the outdoor heat exchanger (124) is lowered. Consequently, when the heating is restarted, the pressure difference between the outdoor heat exchanger (124) and the accumulator (134) is reduced, thereby preventing the inflow of high-pressure liquid refrigerant coming from the outdoor heat exchanger (124). Afterward, the second switching valve (126) is maintained, and the first switching valve (128) is switched to restart the heating operation.

[0149] The air conditioner can control the first switching valve (128) and the second switching valve (126) differently when switching to the heating cycle, depending on the type of the plurality of indoor units (10). For example, the switching type and the simultaneous type may have different control of the switching valve (120) because the connection pipe connection method is different. By performing control in accordance with the air conditioner type, the refrigerant flow can be stably controlled even when the air conditioner type is different.

[0150] The switching type air conditioner can primarily reduce the high-low pressure difference by switching the second switching valve (126) after stopping the cooling cycle in a first stage control, thereby connecting the low-pressure line that is cut off from the accumulator (134) and compressor (122) to the high-pressure line of the condenser (outdoor heat exchanger (124)).

[0151] The simultaneous air conditioner can primarily reduce the high-low pressure difference by switching the second switching valve (126) after stopping the cooling cycle in a first stage control, thereby connecting the accumulator (134) and compressor (122) connection line to the gaseous high-pressure line that is cut off from the condenser (outdoor heat exchanger (124)).

[0152] Afterwards, the simultaneous air conditioner can be switched to the state of the switching valve (120) when switching to the existing (heating operation) mode through 2-stage control.

[0153] When switching from defrosting operation / cooling operation / oil recovery operation to heating operation, the difference between high and low pressure is reduced stepwise, thereby effectively preventing the high-pressure liquid refrigerant used as a condenser in the cooling cycle from flowing excessively into the compressor (122).

[0154] Figure 8 is a drawing referenced in the description of the heating cycle in the system of Figure 2.

[0155] Referring to FIG. 8, in the heating cycle, the first switching valve (128) is controlled to the ON state and the second switching valve (126) is controlled to the OFF state. Accordingly, the refrigerant discharged from the compressor (122) flows to the indoor heat exchanger (112).

[0156] The refrigerant discharged from the compressor (122) can be supplied to the distributor (40) via the discharge path (159), the first switching valve (128), the second switching valve (126), and the second pipe (4). Additionally, the refrigerant can be supplied to the distributor (40) via the third pipe (6). The distributor (40) can supply refrigerant to the indoor heat exchanger (112) according to the indoor load.

[0157] The refrigerant can be recovered through the outdoor heat exchanger (124) to the accumulator (134) and compressor (122).

[0158] Figure 9 is a drawing referenced in the description of the cooling cycle in the system of Figure 2.

[0159] Figure 9 shows a typical reverse cycle defrosting operation (same as cooling operation).

[0160] In the cooling cycle, the first switching valve (128) and the second switching valve (126) are switched on / off so that the outdoor heat exchanger (124) is used as a condenser and the indoor heat exchanger (124) is used as an evaporator.

[0161] Referring to FIG. 9, in the cooling cycle, the first switching valve (128) and the second switching valve (126) are controlled to be off. Accordingly, the refrigerant discharged from the compressor (122) flows to the outdoor heat exchanger (124) and the distributor (40). The refrigerant that has undergone heat exchange in the outdoor heat exchanger (124) can be supplied to the distributor (40). The distributor (40) can supply refrigerant to the indoor heat exchanger (112) according to the indoor load.

[0162] Additionally, the refrigerant passes through the indoor heat exchanger (124), the second pipe (4), and the second switching valve (126), and is recovered in the accumulator (134) and compressor (122).

[0163] Meanwhile, in the case of a simultaneous air conditioner, some of the multiple indoor units (10) may be operated in a heating mode and some in a cooling mode.

[0164] The outdoor heat exchanger (124) can operate as a condenser or an evaporator depending on whether there is a large cooling load or a large heating load. The first switching valve (128) and the second switching valve (126) can also be controlled, like the outdoor heat exchanger (124), depending on whether there is a large cooling load or a large heating load.

[0165] In addition, since the simultaneous air conditioner has various piping connection methods, the refrigerant flow can be configured in a way different from that shown in FIGS. 8 and 9.

[0166] FIGS. 10a to 10c are drawings referenced in the description of simultaneous switching valve control according to one embodiment of the present disclosure.

[0167] FIG. 11 is a flowchart illustrating the operation method of an air conditioner according to one embodiment of the present disclosure, and a switching valve control method in a simultaneous air conditioner is exemplified.

[0168] FIG. 10a illustrates a switching valve (120) and refrigerant flow in a cooling cycle. For example, FIG. 10a illustrates the state of the first switching valve (128) and the second switching valve (126) during a defrosting operation. During a cooling cycle, such as a defrosting operation, the first switching valve (128) is in an off state and the second switching valve (126) is in an on state.

[0169] Referring to FIG. 11, after the defrosting operation is completed (S1110) and before the heating restart (S730), the heating restart of FIG. 10c can be performed after going through the pressure control steps (S1120, S1130) as in FIG. 10b (S1140).

[0170] The normal pressure control step (S1120, S1130) reduces the pressure difference by increasing the low pressure of the accumulator (134) by switching the second switching valve (126) (S1120) and maintaining it for a certain standard time (e.g., about 2 minutes) (S1120).

[0171] When the cooling cycle ends (S1120), the second switching valve (126) is switched to the off state (S1120). After the above reference time has elapsed (S1130), the first switching valve (128) and the second switching valve (126) are switched to the on state.

[0172] The pressure difference between the outdoor heat exchanger (124) and the accumulator (134) is reduced, so that the inflow of high-pressure liquid refrigerant from the outdoor heat exchanger (124) can be prevented when the heating is restarted.

[0173] After the above standard time has elapsed, both the first switching valve (128) and the second switching valve (126) are switched to restart the heating operation.

[0174] Depending on whether the third pipe (6) is used, the air conditioner may perform different control of the first switching valve (128) and the second switching valve (126) when switching to the heating cycle during the restart of heating operation. For example, the third pipe (6) is used only in the simultaneous type, and the control of the switching valve (120) in the switching type and the simultaneous type may be different.

[0175] FIG. 12 is a flowchart illustrating the operation method of an air conditioner according to one embodiment of the present disclosure. FIG. 12 is a flowchart illustrating the mode switching flowchart between a switching type product and a simultaneous type product.

[0176] Referring to FIG. 12, after defrosting is completed (S1210), the second switching valve (126) is switched to a single-stage control for both switching and simultaneous types and maintained for a reference time (N minutes) (S1220). The same control logic can be applied when switching modes from cooling operation and oil recovery operation to heating operation, which have cycle characteristics similar to defrosting operation and the same switching valve (120) control method.

[0177] Afterwards, in the case of a switching type system (S1230), only the first switching valve (128) is switched to restart the heating (S1240).

[0178] If it is a simultaneous type product (S1230), the first switching valve (128) and the second switching valve (126) are both switched to restart the heating (S1250).

[0179] Step 1 is a step of lowering the high pressure to a certain value or raising the low pressure to a certain value depending on the piping configuration and product characteristics. When lowering the high pressure, the accumulator (134) and compressor (122) and the blocked low pressure line are connected to the high pressure line of the condenser (outdoor heat exchanger (124)). When raising the low pressure, the connection line of the accumulator (134) and compressor (122) is connected to the condenser (outdoor heat exchanger (124)) and the blocked high pressure line.

[0180] Step 2 controls the switching valve (120) so that the outdoor heat exchanger (124), the accumulator (134), and the compressor (122) upstream piping are connected.

[0181] Accordingly, liquid refrigerant ingress into the compressor can be prevented, thereby preventing compressor failure and enabling the stable provision of cooling and heating functions. In particular, liquid refrigerant ingress can be effectively prevented when switching from the cooling cycle to the heating cycle.

[0182] Although preferred embodiments of the present disclosure have been illustrated and described above, the present disclosure is not limited to the specific embodiments described above, and it is obvious that various modifications can be made by those skilled in the art without departing from the gist of the present disclosure as claimed in the patent claims.

Claims

1. An outdoor unit comprising a compressor, an accumulator connected to the compressor, a suction path through which refrigerant discharged from the accumulator is supplied to the compressor, a discharge path through which refrigerant is discharged from the compressor, an outdoor heat exchanger that exchanges heat between the refrigerant flowing through the compressor and external air, and a switching valve that switches the outdoor heat exchanger to a condenser or an evaporator; and, A plurality of indoor units connected to the outdoor unit and equipped with an indoor heat exchanger; comprising, The above switching valve is, A first switching valve connected to the outdoor heat exchanger via an outdoor heat exchanger connecting pipe, and It includes a second switching valve connected to the first switching valve via a connecting passage, and When the cooling cycle ends, the first switching valve maintains its state and switches the second switching valve, and An air conditioner that switches to a heating cycle after a preset standard time has elapsed.

2. In Paragraph 1, The above outdoor unit and the above plurality of indoor units are connected by a first pipe and a second pipe, and The first pipe above connects the outdoor heat exchanger and the indoor heat exchanger, and The above second pipe is an air conditioner connecting the above indoor heat exchanger and the above switching valve.

3. In Paragraph 2, The first switching valve is connected to the outdoor heat exchanger connecting pipe and the second pipe, and The above second switching valve is an air conditioner connected to the above second pipe and the above connecting passage.

4. In Paragraph 2, An air conditioner that switches the first switching valve and maintains the state of the second switching valve after the above reference time has elapsed.

5. In Paragraph 2, The above outdoor unit is, An air conditioner further comprising an outdoor expansion valve disposed in the first pipe above.

6. In Paragraph 2, During the above cooling cycle, the first switching valve is in an off state and the second switching valve is in an on state, and When the above cooling cycle ends, the second switching valve is switched to the off state, and An air conditioner in which the first switching valve is switched to the ON state after the above reference time has elapsed.

7. In Paragraph 2, A third pipe is further connected to the above outdoor unit and the above plurality of indoor units, and The above third pipe is an air conditioner connected to the above first switching valve, the above second switching valve, and the above accumulator.

8. In Paragraph 7, An air conditioner that switches between the first switching valve and the second switching valve after the above reference time has elapsed.

9. In Paragraph 8, The first switching valve is connected to the outdoor heat exchanger connecting pipe, the second pipe, and the third pipe, and The above second switching valve is an air conditioner connected to the above second pipe, the above connecting passage and the above third pipe.

10. In Paragraph 7, During the above cooling cycle, the first switching valve is in an off state and the second switching valve is in an on state, and When the above cooling cycle ends, the second switching valve is switched to the off state, and An air conditioner in which the first switching valve and the second switching valve are switched to the ON state after the above reference time has elapsed.

11. In Paragraph 7, An air conditioner further comprising a distributor disposed between the outdoor unit and the plurality of indoor units and connected to the first pipe, the second pipe, and the third pipe.

12. In Paragraph 7, An air conditioner in which the control of the first switching valve and the second switching valve differs when switching to the heating cycle, depending on the type of the plurality of indoor units.

13. In Paragraph 7, An air conditioner in which the control of the first switching valve and the second switching valve differs when switching to the heating cycle, depending on whether the third pipe is used.

14. In Paragraph 1, The above standard time is, An air conditioner corresponding to at least one of the capacity of the air conditioner, the length of the internal pipes, and the internal volume.

15. In Paragraph 1, The above cooling cycle is, An air conditioner in cooling operation, defrosting operation, or oil recovery operation.

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