Air conditioner

Abstract

An air conditioner includes: a compressor; an engine configured to drive the compressor; an exhaust gas reduction device including a catalyst an exhaust gas temperature sensor configured to detect an exhaust gas temperature of the engine; a coolant flow regulator configured to regulate a flow rate of a coolant supplied to the engine; an outdoor heat exchanger; an outdoor fan configured to blow air to the outdoor heat exchanger; and a controller configured to control the engine, the coolant flow regulator, and the outdoor fan, wherein the controller is configured to: control the engine to delay an ignition timing of the engine and control the coolant flow regulator to decrease the flow rate of the coolant, decrease a rotation speed of the outdoor fan to increase a pressure of the refrigerant, and control the engine to increase an RPM of the engine.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation of International Application No. PCT / KR2024 / 000697 designating the United States, filed on Jan. 1, 2024, in the Korean Intellectual Property Receiving Office and claiming priority to Korean Patent Application No. 10-2023-0048460, filed on Apr. 12, 2023, in the Korean Intellectual Property Office, the disclosures of each of which are incorporated by reference herein in their entireties.BACKGROUNDField

[0002] The disclosure relates to an air conditioner, and more particularly, to an air conditioner that compresses a refrigerant using a gas engine.Description of Related Art

[0003] An air conditioner is an apparatus for conditioning air in indoor space using transfer of heat produced from evaporation and condensation of a refrigerant to cool or heat the air and release the cooled or heated air. The air conditioner may circulate the refrigerant through a compressor, an indoor heat exchanger and an outdoor heat exchanger during a cooling operation or a heating operation, and cool or heat the indoor space by releasing the air that has exchanged heat in the indoor heat exchanger into the indoor space.

[0004] Air conditioners may be classified into an electric heat pump (EHP) air conditioner and a gas-engine heat pump (GHP) air conditioner according to a power source for driving a compressor. The EHP type uses electricity as a power source for the compressor, and the GHP type uses fuel, such as liquefied natural gas (LNG) or liquefied petroleum gas (LPG), as a power source for the compressor. The GHP type provides power to the compressor by operating an engine through fuel combustion.

[0005] For example, a compressed natural gas (CNG) engine applied to the GHP type uses natural gas as a main fuel, and delivers power required to operate the compressor through four processes of intake-compression-explosion-exhaust of the fuel. In the process, combustion gas is generated as the fuel combusts.

[0006] Among the combustion gases, nitrogen oxides, carbon monoxide, hydrocarbons, etc., which are harmful to humans and the environment, are discharged after undergoing oxidation and reduction reactions through a catalyst to reduce their concentration.

[0007] However, during low-load operation of the air conditioner, the temperature of the combustion gas may not rise enough to react with the catalyst, and thus the combustion gas may be discharged without undergoing oxidation or reduction reactions with the catalyst.SUMMARY

[0008] Embodiments of the disclosure provide an air conditioner that may reduce exhaust gas by increasing a temperature of engine exhaust gas to activate a catalyst during low-load operation of the air conditioner.

[0009] According to an example embodiment of the disclosure, an air conditioner may include: a compressor configured to compress a refrigerant; an engine configured to use natural gas as fuel and drive the compressor; an exhaust gas reduction device including a catalyst configured to react with exhaust gas generated by the engine; an exhaust gas temperature sensor configured to detect an exhaust gas temperature of the engine; a coolant flow regulator configured to regulate a flow rate of a coolant to be supplied to the engine; an outdoor heat exchanger; an outdoor fan configured to blow air to the outdoor heat exchanger; and a controller, comprising circuitry, configured to control the engine, the coolant flow regulator, and the outdoor fan, wherein the controller may be configured to: based on the exhaust gas temperature being lower than a reference temperature, control the engine to delay an ignition timing of the engine and control the coolant flow regulator to decrease the flow rate of the coolant, based on the exhaust gas temperature being lower than the reference temperature after the ignition timing of the engine is delayed and the flow rate of the coolant is decreased, decrease a rotation speed of the outdoor fan to increase a pressure of the refrigerant, and based on the exhaust gas temperature being lower than the reference temperature after the rotation speed of the outdoor fan is decreased, control the engine to increase a revolutions per minute (RPM) of the engine.BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The above and other aspects, features and advantages of certain embodiments of the present disclosure will be more apparent from the following detailed description, taken in conjunction with the accompanying drawings, in which:

[0011] FIG. 1 is a perspective view illustrating an exterior of an example air conditioner according to various embodiments;

[0012] FIG. 2 is a diagram illustrating an example configuration of an air conditioner according to various embodiments;

[0013] FIG. 3 is a diagram illustrating a flow of refrigerant during a cooling operation of an air conditioner according to various embodiments;

[0014] FIG. 4 is a diagram illustrating a flow of refrigerant during a heating operation of an air conditioner according to various embodiments;

[0015] FIG. 5 is a block diagram illustrating an example configuration of an air conditioner according to various embodiments;

[0016] FIG. 6 is a diagram illustrating an example of low-load operation of an air conditioner according to various embodiments; and

[0017] FIG. 7 is a flowchart illustrating an example method for controlling an air conditioner according to various embodiments.DETAILED DESCRIPTION

[0018] Various example embodiments and the terms used therein are not intended to limit the technology disclosed herein to specific forms, and the disclosure should be understood to include various modifications, equivalents, and / or alternatives to the various embodiments.

[0019] In addition, in describing the drawings, similar reference numerals may be used to designate similar elements.

[0020] In addition, terms used herein are for the purpose of describing the various example embodiments and are not intended to restrict and / or to limit the disclosure. The singular expressions herein may include plural expressions, unless the context clearly dictates otherwise. The terms “comprises”, “includes” and “has” are intended to indicate that there are features, numbers, steps, operations, elements, parts, or combinations thereof described in the disclosure, and do not exclude the presence or addition of one or more other features, numbers, steps, operations, elements, parts, or combinations thereof.

[0021] It will also be understood that when an element is referred to as being “connected to” or “coupled to” another element, it may be directly or indirectly connected to the other element.

[0022] In addition, it will be understood that, although the terms first, second, or the like, may be used herein to describe various components, these components should not be limited by these terms. These terms are simply used to distinguish one component from another. For example, without departing from the technical spirit or essential features of the disclosure, a first element may be referred to as a second element, and also a second element may be referred to as a first element.

[0023] Hereinafter, various example embodiments according to the disclosure are described with reference to accompanying drawings.

[0024] FIG. 1 is a perspective view illustrating an exterior of an example air conditioner according to various embodiments.

[0025] Referring to FIG. 1, an air conditioner 1 includes an outdoor unit 1a arranged in an outdoor space for performing heat exchange between outside air and a refrigerant, and an indoor unit 1b arranged in an indoor space for performing heat exchange between indoor air and a refrigerant. The outdoor unit 1a may be located outside an air conditioning space, and the indoor unit 1b may be located in the air conditioning space. The air conditioning space refers to a space that is cooled or heated by the air conditioner 1. For example, the outdoor unit 1a may be arranged outside a building, and the indoor unit 1b may be arranged in a space separated by a wall from the outside, such as a living room or an office room. The indoor unit 1b may be installed on the ceiling.

[0026] The outdoor unit 1a and the indoor unit 1b are connected through external pipes P1 and P2. A refrigerant may circulate through the outdoor unit 1a, the external pipes P1 and P2 and the indoor unit 1b. One end of the external pipe P1 or P2 may be connected to a piping valve arranged on one side of the outdoor unit 1a. The external pipe P1 or P2 may be connected to the outdoor unit 1a and a refrigerant pipe arranged inside the indoor unit 1b.

[0027] The outdoor unit 1a may include a cabinet 10 forming an exterior, a fan cover 20 for covering the top of the cabinet 10, and an outdoor fan 150 arranged in the cabinet 10. The cabinet 10 may form four sides of the outdoor unit 1a. Although two outdoor fans 150 are illustrated, the disclosure is not limited thereto. The outdoor fan 150 may be arranged in an upper portion in the cabinet 10. An outdoor heat exchanger 130 may be arranged in the cabinet 10.

[0028] For example, the cabinet 10 may be divided into an upper cabinet part 10-1 and a lower cabinet part 10-2. The outdoor fan 150 and the outdoor heat exchanger 130 may be positioned in the upper cabinet part 10-1. Various components included in the outdoor unit 1a, such as an engine 105 to be described later, may be positioned in the lower cabinet part 10-2.

[0029] A fan guard 22 may be arranged on the fan cover 20 to release air and protect the outdoor fan 150. The fan cover 20 may include a discharge port corresponding to the shape of the outdoor fan 150. The fan guard 22 may cover the discharge port of the fan cover 20 and may have the form of a grill or mesh. By operation of the outdoor fan 150, outside air may pass through the inside of the cabinet 10 of the outdoor unit 1a and may then be discharged from the cabinet 10. The air flowing by the operation of the outdoor fan 150 may be discharged from the outdoor unit 1a through the fan guard 22.

[0030] Although it is described in FIG. 1 that the air conditioner 1 includes one outdoor unit 1a and one indoor unit 1b, the air conditioner 1 may include a plurality of outdoor units 1a and a plurality of indoor units 1b. For example, a plurality of indoor units 1b may be connected to one outdoor unit 1a. Furthermore, the form of the indoor unit 1b is not limited to what is described above. Any type of indoor unit 1b may be applied as long as the indoor unit 1b is installed in the indoor space and capable of cooling or heating the indoor space.

[0031] FIG. 2 is a diagram illustrating an example configuration of an air conditioner according to various embodiments.

[0032] Referring to FIG. 2, the air conditioner 1 includes a refrigerant flow path for circulating a refrigerant between the indoor unit 1b and the outdoor unit 1a. The refrigerant circulates through the indoor unit 1b and the outdoor unit 1a along the refrigerant flow path, and may absorb or release heat through a state change (e.g., a state change from gas to liquid, or a state change from liquid to gas).

[0033] The air conditioner 1 may include a liquid pipe P1 connecting the outdoor unit 1a and the indoor unit 1b and serving as a passage through which liquid refrigerant flows, and a gas pipe P2 through which gaseous refrigerant flows. The liquid pipe P1 and the gas pipe P2 may extend to the inside the outdoor unit 1a and the indoor unit 1b.

[0034] The outdoor unit 1a includes a compressor 110 compressing the refrigerant, an outdoor heat exchanger 130 performing heat exchange between outdoor air and the refrigerant, a four-way valve 120 guiding the refrigerant compressed by the compressor 110 to the outdoor heat exchanger 130 or the indoor heat exchanger 230 based on cooling operation or heating operation, and an accumulator 160 preventing / reducing unevaporated liquid refrigerant from flowing into the compressor 110.

[0035] The compressor 110 may operate with electric energy provided from an external power source. The compressor 110 includes a compressor motor (not shown) and compresses a gaseous refrigerant of low pressure into high pressure using the rotational force of the compressor motor. A rotation speed of the compressor 110 may be changed to correspond to a capacity required by the indoor unit 1b. The compressor 110 may be a positive displacement compressor or a dynamic compressor, and various types of compressors that may be considered by a designer may be used.

[0036] The compressor 110 may be driven by the engine 105 that uses natural gas as fuel. In the disclosure, the description is based, for example, and without limitation, on the compressor 110 being driven by the engine 105.

[0037] The engine 105 may generate exhaust gas because the engine 105 uses natural gas as fuel. The exhaust gas may pass through an exhaust gas reduction device 106 and be discharged outside through an exhaust portion 107.

[0038] The exhaust gas reduction device 106 may include a catalyst that reacts with the exhaust gas generated by the engine 105. In this case, the catalyst may be a three-way catalyst, and may react with nitrogen oxides, carbon monoxide, and hydrocarbons, which are harmful to humans and the environment, among the exhaust gas to cause oxidation or reduction reactions to reduce a concentration of the exhaust gas.

[0039] In the exhaust gas reduction device 106, an exhaust gas temperature sensor 176 may be provided to detect a temperature of the exhaust gas.

[0040] A coolant flow path through which coolant passes may be formed in the engine 105. The coolant flow path may lead to an outdoor radiator 146 to lower a temperature of the engine 105.

[0041] To supply the coolant, the air conditioner 1 may include a coolant supply 140 that supplies coolant, a coolant flow regulator 145 that regulates a flow rate of the coolant, and a coolant temperature sensor 177 that detects a temperature of the coolant.

[0042] The four-way valve 120 may change a moving direction of the high temperature and high pressure gaseous refrigerant discharged from the compressor 110. The four-way valve 120 is controlled to guide the refrigerant compressed by the compressor 110 to the outdoor heat exchanger 130 during a cooling operation, and is controlled to guide the refrigerant compressed by the compressor 110 to the indoor unit 1b during a heating operation.

[0043] The outdoor heat exchanger 130 may serve as a condenser that condenses the refrigerant compressed by the compressor 110 during a cooling operation, and may serve as an evaporator that evaporates the refrigerant decompressed in the indoor unit 1b during a heating operation. The outdoor heat exchanger 130 may include an outdoor heat exchanger refrigerant pipe (not shown) through which the refrigerant passes, and an outdoor heat exchanger cooling fin (not shown) to increase a surface area in contact with outdoor air. An increase in the contact surface area between the outdoor heat exchanger refrigerant pipe (not shown) and outdoor air may improve a heat exchange efficiency between the refrigerant and outdoor air.

[0044] The outdoor fan 150 may be positioned around the outdoor heat exchanger 130 to flow outdoor air to the outdoor heat exchanger 130. The outdoor fan 150 may blow outdoor air before heat exchange to the outdoor heat exchanger 130 while simultaneously blowing the heat-exchanged air outdoors. The outdoor fan 150 may disperse heat released by liquefaction of refrigerant in the outdoor heat exchanger 130 by discharging air around the outdoor heat exchanger 130 to the outside.

[0045] The accumulator 160 may store liquid refrigerant and vaporize the stored liquid refrigerant. The accumulator 160 may prevent and / or reduce the liquid refrigerant from flowing into the compressor 110. However, in a case where the amount of refrigerant circulation is excessive, the vaporization of the liquid refrigerant by the accumulator 160 may not be performed properly. In this case, the liquid refrigerant may flow into the compressor 110, and the compressor 110 may be damaged.

[0046] The outdoor unit 1a may include an outdoor temperature sensor 171 for detecting an outdoor temperature. An outdoor heat exchanger temperature sensor 172 for detecting a temperature of the outdoor heat exchanger 130 may be disposed on at least one side of the outdoor heat exchanger 130. The outdoor temperature sensor 171 and the outdoor heat exchanger temperature sensor 172 may be implemented as at least one of a bimetal thermometer, a thermistor thermometer, or an infrared thermometer.

[0047] Based on a cooling operation in which the refrigerant flows from the compressor 110 to the outdoor heat exchanger 130, the outdoor heat exchanger temperature sensor 172 may be disposed on the outlet side of the outdoor heat exchanger 130 from which the refrigerant flows out. Accordingly, the outdoor heat exchanger temperature sensor 172 may be referred to as an ‘outdoor heat exchanger outlet temperature sensor’. Although not illustrated, a temperature sensor (not shown) may also be provided on the inlet side of the outdoor heat exchanger 130, which may be referred to as an ‘outdoor heat exchanger inlet temperature sensor’. In other words, a temperature sensor may be disposed at each of the inlet and outlet of the outdoor heat exchanger 130. The outdoor heat exchanger temperature sensor 172 may be installed around the inlet and / or outlet of the outdoor heat exchanger 130, or may be installed to contact the refrigerant pipe connected to the inlet and / or outlet of the outdoor heat exchanger 130.

[0048] During a heating operation, a circulation direction of the refrigerant is reversed, and thus the inlet of the outdoor heat exchanger 130 where the refrigerant flows in and the outlet of the outdoor heat exchanger 130 where the refrigerant flows out may be defined in reverse. However, for convenience of description, the inlet and outlet of the outdoor heat exchanger 130 may be described based on a cooling operation.

[0049] A compressor outlet temperature sensor 173 may be disposed at the outlet of the compressor 110. The compressor outlet temperature sensor 173 may detect a discharge temperature of the refrigerant discharged from the compressor 110. The discharge temperature of the refrigerant discharged from the compressor 110 may be referred to as a compressor discharge temperature or a compressor outlet temperature.

[0050] A compressor inlet pressure sensor 174 may be disposed at the inlet of the compressor 110. The compressor inlet pressure sensor 174 may detect a pressure of the refrigerant flowing into the compressor 110 from the accumulator 160. The pressure of the refrigerant flowing into the inlet of the compressor 110 may be referred to as a compressor inlet pressure.

[0051] A compressor outlet pressure sensor 175 may be disposed at the outlet of the compressor 110. The compressor outlet pressure sensor 175 may detect a pressure of the refrigerant discharged through the outlet of the compressor 110. The pressure of the refrigerant discharged through the outlet of the compressor 110 may be referred to as a compressor outlet pressure.

[0052] The indoor unit 1b may include an expansion valve 220, the indoor heat exchanger 230, and an indoor fan 250. The indoor heat exchanger 230 performs heat exchange between indoor air and the refrigerant. The indoor fan 250 may cause indoor air to flow to the indoor heat exchanger 230. A plurality of indoor fans 250 may be provided.

[0053] The expansion valve 220 may expand the refrigerant in a high-temperature and high-pressure liquid state and discharge a mixture of gaseous and liquid refrigerants of low temperature and low pressure. The expansion valve 220 may also adjust the amount of refrigerant supplied to the indoor heat exchanger 230. The expansion valve 220 decompresses the refrigerant using throttling actions. Throttling actions refer to a reduction in pressure of the refrigerant when the refrigerant passes through a narrow flow path even without heat exchange with the outside.

[0054] The expansion valve 220 may be an electronic expansion valve (EEV) capable of controlling an opening degree. The expansion valve 220 may be, for example, a thermoelectric electronic expansion valve that uses deformation of a bimetal, a thermostatic electronic expansion valve that uses volumetric expansion by heating enclosed wax, a pulse width modulation type electronic expansion valve for opening or closing a solenoid valve according to a pulse signal, or a step motor type electronic expansion valve that uses a motor to open or close the valve.

[0055] The expansion valve 220 is illustrated as being included in the indoor unit 1b, but the expansion valve 220 may also be included in the outdoor unit 1a. In addition, the expansion valve 220 may be provided in both the outdoor unit 1a and the indoor unit 1b. For example, the expansion valve 220 may be provided in the liquid pipe P1, which is a pipe forming a refrigerant flow path between the outdoor heat exchanger 130 and the indoor heat exchanger 230.

[0056] The indoor heat exchanger 230 may serve as an evaporator that evaporates low-pressure liquid refrigerant during a cooling operation, and may serve as a condenser that condenses high-pressure gaseous refrigerant during a heating operation. The indoor heat exchanger 230, like the outdoor heat exchanger 130 of the outdoor unit 1a, includes an indoor heat exchanger refrigerant pipe (not shown) through which the refrigerant passes, and an indoor heat exchanger cooling fin (not shown) for improving a heat exchange efficiency between the refrigerant and indoor air.

[0057] The indoor fan 250 may be positioned around the indoor heat exchanger 230 to blow indoor air to the indoor heat exchanger 230. The indoor heat exchanger 230 may perform heat exchange with indoor air. The indoor fan 250 may blow indoor air before heat exchange to the indoor heat exchanger 230 while simultaneously blowing the heat-exchanged air into the indoor space.

[0058] Indoor heat exchanger temperature sensors 211 and 212 may be provided on both sides (inlet and outlet) of the indoor heat exchanger 230 to detect a temperature of the indoor heat exchanger 230. The indoor heat exchanger temperature sensors 211 and 212 may be installed around the inlet and / or outlet of the indoor heat exchanger 230, or may be installed to contact the refrigerant pipe connected to the inlet and / or outlet of the indoor heat exchanger 230.

[0059] The indoor heat exchanger temperature sensors 211 and 212 may include the indoor heat exchanger inlet temperature sensor 211 and the indoor heat exchanger outlet temperature sensor 212. The indoor heat exchanger inlet temperature sensor 211 may detect an inlet temperature of the indoor heat exchanger 230, and the indoor heat exchanger outlet temperature sensor 212 may detect an outlet temperature of the indoor heat exchanger 230. The inlet of the indoor heat exchanger 230 into which the refrigerant flows and the outlet of the indoor heat exchanger 230 from which the refrigerant flows out may be defined oppositely in cooling operation and heating operation. However, for convenience of description, the inlet and outlet of the indoor heat exchanger 230 may be described based on a cooling operation.

[0060] In addition, an indoor temperature sensor 213 may be disposed in the indoor unit 1b to detect an indoor temperature. The indoor heat exchanger temperature sensors 211 and 212 and the indoor temperature sensor 213 may be implemented as at least one of a bimetallic thermometer, a thermistor thermometer, or an infrared thermometer.

[0061] The air conditioner 1 may include various temperature sensors.

[0062] FIG. 3 is a diagram illustrating example flow of refrigerant during a cooling operation of an air conditioner according to various embodiments. FIG. 4 is a diagram illustrating example flow of refrigerant during a heating operation of an air conditioner according to various embodiments.

[0063] During a cooling operation, the refrigerant may release heat from the outdoor heat exchanger 130 and absorb heat from an indoor heat exchanger 230. During a cooling operation, the refrigerant compressed in the compressor 110 may be first supplied to the outdoor heat exchanger 130 through a four-way valve 120 and then to the indoor heat exchanger 230 through an expansion valve 220. During a cooling operation, the outdoor heat exchanger 130 may operate as a condenser that condenses the refrigerant, and the indoor heat exchanger 230 may operate as an evaporator that evaporates the refrigerant.

[0064] During a cooling operation, the high-temperature and high-pressure gaseous refrigerant discharged from the compressor 110 moves to the outdoor heat exchanger 130. The liquid or near-liquid refrigerant condensed in the outdoor heat exchanger 130 is expanded and decompressed in the expansion valve 220. Two-phase refrigerant that has passed through the expansion valve 220 moves to the indoor heat exchanger 230. The refrigerant flowing into the indoor heat exchanger 230 exchanges heat with ambient air and evaporates. Accordingly, a temperature of the heat-exchanged ambient air decreases and cold air is discharged to the outside of the indoor unit 1b.

[0065] During a heating operation, the refrigerant may release heat from the indoor heat exchanger 230 and absorb heat from the outdoor heat exchanger 130. That is, during a heating operation, the refrigerant compressed in the compressor 110 may be first supplied to the indoor heat exchanger 230 through the four-way valve 120 and then to the outdoor heat exchanger 130. In this case, the indoor heat exchanger 230 may operate as a condenser that condenses the refrigerant, and the outdoor heat exchanger 130 may operate as an evaporator that evaporates the refrigerant.

[0066] During a heating operation, the high-temperature and high-pressure gaseous refrigerant discharged from the compressor 110 moves to the indoor heat exchanger 230. The high-temperature and high-pressure gaseous refrigerant passing through the indoor heat exchanger 230 exchanges heat with low-temperature and dry air. The refrigerant is condensed into a liquid or near-liquid refrigerant and releases heat, and as the air absorbs the heat, warm air is discharged to the outside of the indoor unit 1b.

[0067] FIG. 5 is a block diagram illustrating an example configuration of an air conditioner according to various embodiments. FIG. 6 is a diagram illustrating an example of low-load operation of an air conditioner according to various embodiments.

[0068] Referring to FIG. 5, the outdoor unit 1a of the air conditioner 1 may include the engine 105 for driving the compressor 110, the four-way valve 120, the coolant flow regulator 145, the outdoor fan 150, the outdoor temperature sensor 171, the outdoor heat exchanger temperature sensor 172, the compressor outlet temperature sensor 173, the compressor inlet pressure sensor 174, the compressor outlet pressure sensor 175, the exhaust gas temperature sensor 176, the coolant temperature sensor 177, a communication interface (e.g., including communication circuitry) 180, and a controller (e.g., including various circuitry) 190. The controller 190 may include a memory 192 and a processor (e.g., including processing circuitry) 191.

[0069] The controller 190 may be electrically connected to components of the outdoor unit 1a and may include various circuitry to control the operation of each component. For example, the controller 190 may control the engine 105 that drives the compressor 110, may control the coolant flow regulator 145 to regulate a flow rate of coolant, and may control the four-way valve 120 to allow a circulation direction of refrigerant to be switched. The controller 190 may control a rotation speed of the outdoor fan 150. The rotation speed of the outdoor fan 150 may be controlled according to an outdoor temperature. In addition, the controller 190 may generate a control signal to control an opening degree of the expansion valve 220 of the indoor unit 1b.

[0070] Under the control of the controller 190, the refrigerant may circulate along a refrigerant circulation flow path including the compressor 110, the four-way valve 120, the outdoor heat exchanger 130, the expansion valve 220, and the indoor heat exchanger 230. The compressor 110 may compress a gaseous refrigerant and discharge a high-temperature and high-pressure gaseous refrigerant. In addition, the compressor 110 may not operate in a blowing operation that does not require cooling or heating.

[0071] The four-way valve 120 may switch the circulation direction of the refrigerant discharged from the compressor 110 under the control of the controller 190. The four-way valve 120 guides the refrigerant compressed in the compressor 110 to the outdoor heat exchanger 130 during a cooling operation, and guides the refrigerant compressed in the compressor 110 to the indoor heat exchanger 230 during a heating operation.

[0072] The outdoor temperature sensor 171 may transmit an electrical signal corresponding to a detected outdoor temperature to the controller 190. The outdoor heat exchanger temperature sensor 172 may transmit an electrical signal corresponding to a detected inlet temperature and / or a detected outlet temperature of the outdoor heat exchanger to the controller 190.

[0073] The compressor outlet temperature sensor 173 may transmit an electrical signal corresponding to a compressor discharge temperature to the controller 190. The compressor inlet pressure sensor 174 may transmit an electrical signal corresponding to a compressor inlet pressure to the controller 190. The compressor outlet pressure sensor 175 may transmit an electrical signal corresponding to a compressor outlet pressure to the controller 190.

[0074] The exhaust gas temperature sensor 176 may transmit an electrical signal corresponding to a detected exhaust gas temperature to the controller 190. The coolant temperature sensor 177 may transmit an electrical signal corresponding to a detected coolant temperature to the controller 190.

[0075] The communication interface 180 may include various communication circuitry and communicate with the indoor unit 1b. The communication interface 180 of the outdoor unit 1a may transmit a control signal transmitted from the controller 190 to the indoor unit 1b, or may transmit a control signal transmitted from the indoor unit 1b to the controller 190. In other words, the outdoor unit 1a and the indoor unit 1b may perform bi-directional communication. The outdoor unit 1a and the indoor unit 1b may transmit or receive various signals during operation.

[0076] The memory 192 may record / store various information required for operation of the air conditioner 1. The memory 192 may store instructions, applications, data, and / or programs required for operation of the air conditioner 1. For example, the memory 192 may store programs for cooling operation, heating operation, and defrosting operation of the air conditioner 1.

[0077] The memory 192 may include volatile memory, such as static random access memory (S-RAM), dynamic random access memory (D-RAM) for temporarily storing data. In addition, the memory 192 may include non-volatile memory, such as read only memory (ROM), an erasable programmable read only memory (EPROM), electrically erasable programmable read only memory (EEPROM), and the like, for long-term data storage.

[0078] The processor 191 may include various processing circuitry and generate a control signal for controlling an operation of the air conditioner 1 based on the instructions, applications, and data stored in the memory 192. The processor 191 may include a logic circuit and an arithmetic circuit in hardware. The processor 191 may process data according to the programs and / or instructions provided from the memory 192, and generate a control signal according the processing result. The memory 192 and the processor 191 may be implemented as a single control circuit or a plurality of circuits. Thus, the processor 191 may include various processing circuitry and / or multiple processors. For example, as used herein, including the claims, the term “processor” may include various processing circuitry, including at least one processor, wherein one or more of at least one processor, individually and / or collectively in a distributed manner, may be configured to perform various functions described herein. As used herein, when “a processor”, “at least one processor”, and “one or more processors” are described as being configured to perform numerous functions, these terms cover situations, for example and without limitation, in which one processor performs some of recited functions and another processor(s) performs other of recited functions, and also situations in which a single processor may perform all recited functions. Additionally, the at least one processor may include a combination of processors performing various of the recited / disclosed functions, e.g., in a distributed manner. At least one processor may execute program instructions to achieve or perform various functions.

[0079] Some of the above-described components of the outdoor unit 1a may be omitted, or other components may be added in addition to the above-described components of the outdoor unit 1a. For example, the outdoor unit 1a may further include a control panel. The control panel may be provided on the cabinet 10 of the outdoor unit 1a. The control panel may obtain an input (e.g., a user input) related to the operation of the air conditioner 1, and may output information about the operation of the air conditioner 1. The control panel may transmit an electrical signal (voltage or current) corresponding to the user input to the controller 190. The controller 190 may control the operation of the air conditioner 1 based on the electrical signal transmitted from the control panel. The control panel may include buttons and a display.

[0080] Hereinafter, an example operation for reducing engine exhaust gas in a case where the air conditioner 1 operates at a low load is described in greater detail.

[0081] Referring to FIG. 6, it is seen that the current temperature is 25° C., the air conditioner 1 is set to a set temperature of 24° C., and the air volume is set to low. As such, a situation may occur where the air conditioner 1 operates at a low load, such as performing a heating operation when the outside temperature is relatively high, or conversely, performing a cooling operation when the outside temperature is relatively low. In addition, in a case where only some of a plurality of indoor units 1b connected to one outdoor unit 1a are operating, the air conditioner 1 may also operate at a low load.

[0082] As such, in the case of low-load operation of the air conditioner 1, a temperature of the engine 105 may not rise sufficiently, and thus a temperature of the exhaust gas generated by the engine 105 may not increase to a sufficient temperature to react with a catalyst.

[0083] Accordingly, reacting the exhaust gas generated by the engine 105 with the catalyst is required to reduce a concentration of the exhaust gas. A method to induce an active reaction with the catalyst by temporarily increasing the load of the engine 105 to increase the temperature of the exhaust gas is described below.

[0084] A condition for determining whether the air conditioner 1 is operating at a low load is described, Whether the air conditioner 1 is operating at a low load may be determined by various methods. For example, in a case where a temperature of the exhaust gas detected by the exhaust gas temperature sensor 176 is lower than a reference temperature, it may be determined that the air conditioner 1 is operating at a low load. Here, the reference temperature may be set close to the temperature at which the exhaust gas reacts most actively with the catalyst, which may be approximately 380° C. However, the above temperature is only an example, and the reference temperature may be set to various values to determine whether the air conditioner 1 is operating at a low load.

[0085] As another example, in a case where a difference between an indoor temperature and a set temperature of the air conditioner 1 is lower than a preset temperature, it may be determined that the air conditioner 1 is operating at a low load. Here, the preset temperature may be set to various values to determine whether the air conditioner 1 is operating at a low load.

[0086] In a case where a plurality of indoor units 1b are connected to a single outdoor unit 1a and fewer than a reference number of the plurality of indoor units 1b are operating, it may be determined that the air conditioner 1 is operating at a low load. The reference number may also be set to various values to determine whether the air conditioner 1 is operating at a low load.

[0087] Whether the air conditioner 1 is operating at a low load may be determined according to various conditions.

[0088] Hereinafter, a case in which the condition for determining a low-load operation of the air conditioner 1 is an exhaust gas temperature lower than the reference temperature is described.

[0089] Based on determining that the temperature of the exhaust gas is lower than the reference temperature, the controller 190 may control the engine 105 to increase an output of the engine 105. For example, the temperature of the engine 105 may be increased by increasing a load of the engine 105 by increasing a revolutions per minute (RPM) of the engine 105 to a reference RPM or higher. The reference RPM may be set to 600 RPM during a cooling operation and 700 RPM during a heating operation. However, the above reference RPMs are only an example and may be set to various values that may increase the load of the engine 105.

[0090] Increasing the output of the engine 105 described above may be applied during both cooling mode and heating mode of the air conditioner 1.

[0091] Based on determining that the temperature of the exhaust gas is lower than the reference temperature, the controller 190 may control the engine 105 to delay an ignition timing of the engine 105.

[0092] The ignition timing of the engine 105 may be predetermined according to an RPM of an engine motor. However, in the case of low-load operation of the air conditioner 1, the controller 190 may perform retard control on a reference ignition timing, and thus the temperature of the exhaust gas may rise as the ignition timing is delayed.

[0093] Delaying the ignition timing of the engine 105 described above may be applied during both cooling mode and heating mode of the air conditioner 1.

[0094] Based on determining that the temperature of the exhaust gas is lower than the reference temperature, the controller 190 may control the coolant flow regulator 145 to decrease a flow rate of coolant.

[0095] By reducing the flow rate of the coolant flowing through the engine 105, a decrease in the temperature of the engine 105 may be reduced, and thus a decrease in the temperature of the exhaust gas may also be reduced.

[0096] The coolant flow rate control may described above may consider not only the temperature of the exhaust gas detected by the exhaust gas temperature sensor 176 but also the temperature of the coolant detected by the coolant temperature sensor 177.

[0097] Regulating the flow rate of the coolant described above may be applied during both cooling mode and heating mode of the air conditioner 1.

[0098] Based on determining that the temperature of the exhaust gas is lower than the reference temperature, the controller 190 may control the outdoor fan 150 to decrease a rotation speed of the outdoor fan 150 during a cooling mode of the air conditioner 1.

[0099] As the rotation speed of the outdoor fan 150 decreases, a pressure of the refrigerant detected by the compressor outlet pressure sensor 175 increases, and thus a load of the engine 105 may increase.

[0100] To appropriately increase the load of the engine 105, the rotation speed of the outdoor fan 150 may be controlled based on a pressure of the refrigerant detected by the compressor outlet pressure sensor 175. For example, in a case where the pressure of the refrigerant detected by the compressor outlet pressure sensor 175 is lower than a reference pressure, the rotation speed of the outdoor fan 150 may decrease to allow the pressure of the refrigerant to reach or exceed the reference pressure. Here, the reference pressure may be 2.5 MPa. However, the reference pressure is only an example and may be set to various values for an appropriate load increase of the engine 105.

[0101] Decreasing the rotation speed of the outdoor fan 150 described above may be applied when the air conditioner 1 operates in a cooling mode.

[0102] According to the operation of the controller 190 of controlling the engine 105, the coolant flow regulator 145, and the outdoor fan 150, the load and temperature of the engine 105 increase, and thus the temperature of the exhaust gas generated by the engine may also increase.

[0103] The controller 190 may perform the above operations of controlling the engine 105, the coolant flow regulator 145, and the outdoor fan 150 simultaneously to increase the temperature of the exhaust gas. The controller 190 may also control the engine 105, the coolant flow regulator 145, and the outdoor fan 150 sequentially to increase the temperature of the exhaust gas more efficiently.

[0104] For example, based on the exhaust gas temperature being lower than the reference temperature, the controller 190 may first control the engine 105 and the coolant flow regulator 145 to delay the ignition timing of the engine 105 and decrease the flow rate of the coolant.

[0105] Even after controlling the engine 105 and the coolant flow regulator 145 to delay the ignition timing of the engine and decrease the flow rate of the coolant, the exhaust gas temperature may not rise sufficiently. In this case, the controller 190 may control the outdoor fan 150 to decrease the rotation speed of the outdoor fan 150.

[0106] For example, based on the exhaust gas temperature being lower than the reference temperature after the ignition timing of the engine 105 is delayed and the flow rate of the coolant is decreased, the rotation speed of the outdoor fan 150 may be decreased to increase a pressure of the refrigerant.

[0107] In a case where the exhaust gas temperature does not rise sufficiently even after decreasing the rotation speed of the outdoor fan 150, the controller 190 may control the engine 105 to increase an RPM of the engine 105.

[0108] For example, based on the exhaust gas temperature being lower than the reference temperature after the rotation speed of the outdoor fan 150 is decreased, the controller 190 may control the engine 105 to increase an RPM of the engine 105.

[0109] Due to the increase in the exhaust gas temperature, the oxidation or reduction reaction with the catalyst becomes more active, and as a result, a concentration of the exhaust gas may decrease.

[0110] For example, by reducing a concentration of nitrogen oxides, carbon monoxide, hydrocarbons, etc., which are harmful to humans and the environment, a positive effect on the environment may occur.

[0111] FIG. 7 is a flowchart illustrating an example method for controlling an air conditioner according to various embodiments.

[0112] The controller 190 may detect whether a low-load operation condition of the air conditioner 1 is satisfied (701).

[0113] As described above, whether the air conditioner 1 is operating at a low load may be determined based on whether a temperature of an exhaust gas detected by the exhaust gas temperature sensor 176 is lower than a reference temperature.

[0114] As another example, whether the air conditioner 1 is operating at a low load may be determined according to various conditions, such as in a case where a difference between an indoor temperature and a set temperature of the air conditioner 1 is lower than a preset temperature, or in a case where a plurality of indoor units 1b are connected to a single outdoor unit 1a and fewer than a reference number of the plurality of indoor units 1b are operating.

[0115] In response to the low-load operation condition of the air conditioner 1 not being satisfied (No in operation 703), the controller 190 may control the air conditioner 1 to operate normally (707).

[0116] In response to the low-load operation condition of the air conditioner 1 being satisfied (Yes in operation 703), for example, based on determining that the temperature of the exhaust gas is lower than the reference temperature, the controller 190 may control the engine 105, the coolant flow regulator 145, and the outdoor fan 150 for exhaust gas reduction control (705).

[0117] For example, the controller 190 may control the engine 105 to increase an output of the engine 105 and delay an ignition timing of the engine 105. In addition, the controller 190 may decrease a flow rate of the coolant flowing through the engine 105. The above-described control may be applied during both cooling mode and heating mode of the air conditioner 1.

[0118] When the air conditioner 1 operates in a cooling mode, the controller 190 may control the outdoor fan 150 to decrease a rotation speed of the outdoor fan 150.

[0119] According to an embodiment of the disclosure, an air conditioner may include: a compressor configured to compress a refrigerant; an engine configured to use natural gas as fuel and drive the compressor; an exhaust gas reduction device including a catalyst that reacts with exhaust gas generated by the engine; an exhaust gas temperature sensor configured to detect an exhaust gas temperature of the engine; a coolant flow regulator configured to regulate a flow rate of a coolant supplied to the engine; an outdoor heat exchanger; an outdoor fan configured to blow air to the outdoor heat exchanger; and a controller configured to control the engine, the coolant flow regulator, and the outdoor fan, wherein the controller may be configured to, based on the exhaust gas temperature being lower than a reference temperature, control the engine to delay an ignition timing of the engine and increase an output of the engine, and control the coolant flow regulator to decrease the flow rate of the coolant.

[0120] According to the disclosure, during a low-load operation of the air conditioner, the exhaust gas may be reduced by increasing the load of the engine to increase the temperature of the engine and activate the reaction between the exhaust gas and the catalyst due to the increase in the engine exhaust temperature gas.

[0121] During a cooling mode of the air conditioner, the controller may be configured to control the outdoor fan to decrease a rotation speed of the outdoor fan, based on the exhaust gas temperature being lower than the reference temperature.

[0122] The air conditioner may further include a compressor outlet pressure sensor configured to detect a pressure of the refrigerant compressed in the compressor, wherein the controller may be configured to decrease a rotation speed of the outdoor fan to allow the pressure of the refrigerant detected by the compressor outlet pressure sensor to be greater than or equal to a reference pressure.

[0123] During a cooling mode or a heating mode of the air conditioner, the controller may be configured to control the engine to delay an ignition timing of the engine and increase an output of the engine, based on the exhaust gas temperature being lower than the reference temperature.

[0124] During a cooling mode or a heating mode of the air conditioner, the controller may be configured to the coolant flow regulator to decrease the flow rate of the coolant, based on the exhaust gas temperature being lower than the reference temperature.

[0125] The various disclosed example embodiments may be implemented in the form of a recording medium that stores instructions executable by a computer. The instructions may be stored in the form of program codes, and when executed by a processor, the instructions may create a program module to perform operations of the disclosed embodiments. The recording medium may be implemented as a computer-readable recording medium.

[0126] The computer-readable recording medium may include all kinds of recording media storing instructions that can be interpreted by a computer. For example, the computer-readable recording medium may be read only memory (ROM), random access memory (RAM), a magnetic tape, a magnetic disc, a flash memory, an optical data storage device, etc.

[0127] Although various example embodiments of the disclosure have been described with reference to the accompanying drawings, one skilled in the art will appreciate that other specific modifications may be easily made without departing from the technical spirit or essential features of the disclosure. Therefore, the foregoing example embodiments should be regarded as illustrative rather than limiting in all respects.

Examples

Embodiment Construction

[0018]Various example embodiments and the terms used therein are not intended to limit the technology disclosed herein to specific forms, and the disclosure should be understood to include various modifications, equivalents, and / or alternatives to the various embodiments.

[0019]In addition, in describing the drawings, similar reference numerals may be used to designate similar elements.

[0020]In addition, terms used herein are for the purpose of describing the various example embodiments and are not intended to restrict and / or to limit the disclosure. The singular expressions herein may include plural expressions, unless the context clearly dictates otherwise. The terms “comprises”, “includes” and “has” are intended to indicate that there are features, numbers, steps, operations, elements, parts, or combinations thereof described in the disclosure, and do not exclude the presence or addition of one or more other features, numbers, steps, operations, elements, parts, or combinations th...

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation of International Application No. PCT / KR2024 / 000697 designating the United States, filed on Jan. 1, 2024, in the Korean Intellectual Property Receiving Office and claiming priority to Korean Patent Application No. 10-2023-0048460, filed on Apr. 12, 2023, in the Korean Intellectual Property Office, the disclosures of each of which are incorporated by reference herein in their entireties.BACKGROUNDField

[0002] The disclosure relates to an air conditioner, and more particularly, to an air conditioner that compresses a refrigerant using a gas engine.Description of Related Art

[0003] An air conditioner is an apparatus for conditioning air in indoor space using transfer of heat produced from evaporation and condensation of a refrigerant to cool or heat the air and release the cooled or heated air. The air conditioner may circulate the refrigerant through a compressor, an indoor heat exchanger and an outdoor heat exchanger during a cooling operation or a heating operation, and cool or heat the indoor space by releasing the air that has exchanged heat in the indoor heat exchanger into the indoor space.

[0004] Air conditioners may be classified into an electric heat pump (EHP) air conditioner and a gas-engine heat pump (GHP) air conditioner according to a power source for driving a compressor. The EHP type uses electricity as a power source for the compressor, and the GHP type uses fuel, such as liquefied natural gas (LNG) or liquefied petroleum gas (LPG), as a power source for the compressor. The GHP type provides power to the compressor by operating an engine through fuel combustion.

[0005] For example, a compressed natural gas (CNG) engine applied to the GHP type uses natural gas as a main fuel, and delivers power required to operate the compressor through four processes of intake-compression-explosion-exhaust of the fuel. In the process, combustion gas is generated as the fuel combusts.

[0006] Among the combustion gases, nitrogen oxides, carbon monoxide, hydrocarbons, etc., which are harmful to humans and the environment, are discharged after undergoing oxidation and reduction reactions through a catalyst to reduce their concentration.

[0007] However, during low-load operation of the air conditioner, the temperature of the combustion gas may not rise enough to react with the catalyst, and thus the combustion gas may be discharged without undergoing oxidation or reduction reactions with the catalyst.SUMMARY

[0008] Embodiments of the disclosure provide an air conditioner that may reduce exhaust gas by increasing a temperature of engine exhaust gas to activate a catalyst during low-load operation of the air conditioner.

[0009] According to an example embodiment of the disclosure, an air conditioner may include: a compressor configured to compress a refrigerant; an engine configured to use natural gas as fuel and drive the compressor; an exhaust gas reduction device including a catalyst configured to react with exhaust gas generated by the engine; an exhaust gas temperature sensor configured to detect an exhaust gas temperature of the engine; a coolant flow regulator configured to regulate a flow rate of a coolant to be supplied to the engine; an outdoor heat exchanger; an outdoor fan configured to blow air to the outdoor heat exchanger; and a controller, comprising circuitry, configured to control the engine, the coolant flow regulator, and the outdoor fan, wherein the controller may be configured to: based on the exhaust gas temperature being lower than a reference temperature, control the engine to delay an ignition timing of the engine and control the coolant flow regulator to decrease the flow rate of the coolant, based on the exhaust gas temperature being lower than the reference temperature after the ignition timing of the engine is delayed and the flow rate of the coolant is decreased, decrease a rotation speed of the outdoor fan to increase a pressure of the refrigerant, and based on the exhaust gas temperature being lower than the reference temperature after the rotation speed of the outdoor fan is decreased, control the engine to increase a revolutions per minute (RPM) of the engine.BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The above and other aspects, features and advantages of certain embodiments of the present disclosure will be more apparent from the following detailed description, taken in conjunction with the accompanying drawings, in which:

[0011] FIG. 1 is a perspective view illustrating an exterior of an example air conditioner according to various embodiments;

[0012] FIG. 2 is a diagram illustrating an example configuration of an air conditioner according to various embodiments;

[0013] FIG. 3 is a diagram illustrating a flow of refrigerant during a cooling operation of an air conditioner according to various embodiments;

[0014] FIG. 4 is a diagram illustrating a flow of refrigerant during a heating operation of an air conditioner according to various embodiments;

[0015] FIG. 5 is a block diagram illustrating an example configuration of an air conditioner according to various embodiments;

[0016] FIG. 6 is a diagram illustrating an example of low-load operation of an air conditioner according to various embodiments; and

[0017] FIG. 7 is a flowchart illustrating an example method for controlling an air conditioner according to various embodiments.DETAILED DESCRIPTION

[0018] Various example embodiments and the terms used therein are not intended to limit the technology disclosed herein to specific forms, and the disclosure should be understood to include various modifications, equivalents, and / or alternatives to the various embodiments.

[0019] In addition, in describing the drawings, similar reference numerals may be used to designate similar elements.

[0020] In addition, terms used herein are for the purpose of describing the various example embodiments and are not intended to restrict and / or to limit the disclosure. The singular expressions herein may include plural expressions, unless the context clearly dictates otherwise. The terms “comprises”, “includes” and “has” are intended to indicate that there are features, numbers, steps, operations, elements, parts, or combinations thereof described in the disclosure, and do not exclude the presence or addition of one or more other features, numbers, steps, operations, elements, parts, or combinations thereof.

[0021] It will also be understood that when an element is referred to as being “connected to” or “coupled to” another element, it may be directly or indirectly connected to the other element.

[0022] In addition, it will be understood that, although the terms first, second, or the like, may be used herein to describe various components, these components should not be limited by these terms. These terms are simply used to distinguish one component from another. For example, without departing from the technical spirit or essential features of the disclosure, a first element may be referred to as a second element, and also a second element may be referred to as a first element.

[0023] Hereinafter, various example embodiments according to the disclosure are described with reference to accompanying drawings.

[0024] FIG. 1 is a perspective view illustrating an exterior of an example air conditioner according to various embodiments.

[0025] Referring to FIG. 1, an air conditioner 1 includes an outdoor unit 1a arranged in an outdoor space for performing heat exchange between outside air and a refrigerant, and an indoor unit 1b arranged in an indoor space for performing heat exchange between indoor air and a refrigerant. The outdoor unit 1a may be located outside an air conditioning space, and the indoor unit 1b may be located in the air conditioning space. The air conditioning space refers to a space that is cooled or heated by the air conditioner 1. For example, the outdoor unit 1a may be arranged outside a building, and the indoor unit 1b may be arranged in a space separated by a wall from the outside, such as a living room or an office room. The indoor unit 1b may be installed on the ceiling.

[0026] The outdoor unit 1a and the indoor unit 1b are connected through external pipes P1 and P2. A refrigerant may circulate through the outdoor unit 1a, the external pipes P1 and P2 and the indoor unit 1b. One end of the external pipe P1 or P2 may be connected to a piping valve arranged on one side of the outdoor unit 1a. The external pipe P1 or P2 may be connected to the outdoor unit 1a and a refrigerant pipe arranged inside the indoor unit 1b.

[0027] The outdoor unit 1a may include a cabinet 10 forming an exterior, a fan cover 20 for covering the top of the cabinet 10, and an outdoor fan 150 arranged in the cabinet 10. The cabinet 10 may form four sides of the outdoor unit 1a. Although two outdoor fans 150 are illustrated, the disclosure is not limited thereto. The outdoor fan 150 may be arranged in an upper portion in the cabinet 10. An outdoor heat exchanger 130 may be arranged in the cabinet 10.

[0028] For example, the cabinet 10 may be divided into an upper cabinet part 10-1 and a lower cabinet part 10-2. The outdoor fan 150 and the outdoor heat exchanger 130 may be positioned in the upper cabinet part 10-1. Various components included in the outdoor unit 1a, such as an engine 105 to be described later, may be positioned in the lower cabinet part 10-2.

[0029] A fan guard 22 may be arranged on the fan cover 20 to release air and protect the outdoor fan 150. The fan cover 20 may include a discharge port corresponding to the shape of the outdoor fan 150. The fan guard 22 may cover the discharge port of the fan cover 20 and may have the form of a grill or mesh. By operation of the outdoor fan 150, outside air may pass through the inside of the cabinet 10 of the outdoor unit 1a and may then be discharged from the cabinet 10. The air flowing by the operation of the outdoor fan 150 may be discharged from the outdoor unit 1a through the fan guard 22.

[0030] Although it is described in FIG. 1 that the air conditioner 1 includes one outdoor unit 1a and one indoor unit 1b, the air conditioner 1 may include a plurality of outdoor units 1a and a plurality of indoor units 1b. For example, a plurality of indoor units 1b may be connected to one outdoor unit 1a. Furthermore, the form of the indoor unit 1b is not limited to what is described above. Any type of indoor unit 1b may be applied as long as the indoor unit 1b is installed in the indoor space and capable of cooling or heating the indoor space.

[0031] FIG. 2 is a diagram illustrating an example configuration of an air conditioner according to various embodiments.

[0032] Referring to FIG. 2, the air conditioner 1 includes a refrigerant flow path for circulating a refrigerant between the indoor unit 1b and the outdoor unit 1a. The refrigerant circulates through the indoor unit 1b and the outdoor unit 1a along the refrigerant flow path, and may absorb or release heat through a state change (e.g., a state change from gas to liquid, or a state change from liquid to gas).

[0033] The air conditioner 1 may include a liquid pipe P1 connecting the outdoor unit 1a and the indoor unit 1b and serving as a passage through which liquid refrigerant flows, and a gas pipe P2 through which gaseous refrigerant flows. The liquid pipe P1 and the gas pipe P2 may extend to the inside the outdoor unit 1a and the indoor unit 1b.

[0034] The outdoor unit 1a includes a compressor 110 compressing the refrigerant, an outdoor heat exchanger 130 performing heat exchange between outdoor air and the refrigerant, a four-way valve 120 guiding the refrigerant compressed by the compressor 110 to the outdoor heat exchanger 130 or the indoor heat exchanger 230 based on cooling operation or heating operation, and an accumulator 160 preventing / reducing unevaporated liquid refrigerant from flowing into the compressor 110.

[0035] The compressor 110 may operate with electric energy provided from an external power source. The compressor 110 includes a compressor motor (not shown) and compresses a gaseous refrigerant of low pressure into high pressure using the rotational force of the compressor motor. A rotation speed of the compressor 110 may be changed to correspond to a capacity required by the indoor unit 1b. The compressor 110 may be a positive displacement compressor or a dynamic compressor, and various types of compressors that may be considered by a designer may be used.

[0036] The compressor 110 may be driven by the engine 105 that uses natural gas as fuel. In the disclosure, the description is based, for example, and without limitation, on the compressor 110 being driven by the engine 105.

[0037] The engine 105 may generate exhaust gas because the engine 105 uses natural gas as fuel. The exhaust gas may pass through an exhaust gas reduction device 106 and be discharged outside through an exhaust portion 107.

[0038] The exhaust gas reduction device 106 may include a catalyst that reacts with the exhaust gas generated by the engine 105. In this case, the catalyst may be a three-way catalyst, and may react with nitrogen oxides, carbon monoxide, and hydrocarbons, which are harmful to humans and the environment, among the exhaust gas to cause oxidation or reduction reactions to reduce a concentration of the exhaust gas.

[0039] In the exhaust gas reduction device 106, an exhaust gas temperature sensor 176 may be provided to detect a temperature of the exhaust gas.

[0040] A coolant flow path through which coolant passes may be formed in the engine 105. The coolant flow path may lead to an outdoor radiator 146 to lower a temperature of the engine 105.

[0041] To supply the coolant, the air conditioner 1 may include a coolant supply 140 that supplies coolant, a coolant flow regulator 145 that regulates a flow rate of the coolant, and a coolant temperature sensor 177 that detects a temperature of the coolant.

[0042] The four-way valve 120 may change a moving direction of the high temperature and high pressure gaseous refrigerant discharged from the compressor 110. The four-way valve 120 is controlled to guide the refrigerant compressed by the compressor 110 to the outdoor heat exchanger 130 during a cooling operation, and is controlled to guide the refrigerant compressed by the compressor 110 to the indoor unit 1b during a heating operation.

[0043] The outdoor heat exchanger 130 may serve as a condenser that condenses the refrigerant compressed by the compressor 110 during a cooling operation, and may serve as an evaporator that evaporates the refrigerant decompressed in the indoor unit 1b during a heating operation. The outdoor heat exchanger 130 may include an outdoor heat exchanger refrigerant pipe (not shown) through which the refrigerant passes, and an outdoor heat exchanger cooling fin (not shown) to increase a surface area in contact with outdoor air. An increase in the contact surface area between the outdoor heat exchanger refrigerant pipe (not shown) and outdoor air may improve a heat exchange efficiency between the refrigerant and outdoor air.

[0044] The outdoor fan 150 may be positioned around the outdoor heat exchanger 130 to flow outdoor air to the outdoor heat exchanger 130. The outdoor fan 150 may blow outdoor air before heat exchange to the outdoor heat exchanger 130 while simultaneously blowing the heat-exchanged air outdoors. The outdoor fan 150 may disperse heat released by liquefaction of refrigerant in the outdoor heat exchanger 130 by discharging air around the outdoor heat exchanger 130 to the outside.

[0045] The accumulator 160 may store liquid refrigerant and vaporize the stored liquid refrigerant. The accumulator 160 may prevent and / or reduce the liquid refrigerant from flowing into the compressor 110. However, in a case where the amount of refrigerant circulation is excessive, the vaporization of the liquid refrigerant by the accumulator 160 may not be performed properly. In this case, the liquid refrigerant may flow into the compressor 110, and the compressor 110 may be damaged.

[0046] The outdoor unit 1a may include an outdoor temperature sensor 171 for detecting an outdoor temperature. An outdoor heat exchanger temperature sensor 172 for detecting a temperature of the outdoor heat exchanger 130 may be disposed on at least one side of the outdoor heat exchanger 130. The outdoor temperature sensor 171 and the outdoor heat exchanger temperature sensor 172 may be implemented as at least one of a bimetal thermometer, a thermistor thermometer, or an infrared thermometer.

[0047] Based on a cooling operation in which the refrigerant flows from the compressor 110 to the outdoor heat exchanger 130, the outdoor heat exchanger temperature sensor 172 may be disposed on the outlet side of the outdoor heat exchanger 130 from which the refrigerant flows out. Accordingly, the outdoor heat exchanger temperature sensor 172 may be referred to as an ‘outdoor heat exchanger outlet temperature sensor’. Although not illustrated, a temperature sensor (not shown) may also be provided on the inlet side of the outdoor heat exchanger 130, which may be referred to as an ‘outdoor heat exchanger inlet temperature sensor’. In other words, a temperature sensor may be disposed at each of the inlet and outlet of the outdoor heat exchanger 130. The outdoor heat exchanger temperature sensor 172 may be installed around the inlet and / or outlet of the outdoor heat exchanger 130, or may be installed to contact the refrigerant pipe connected to the inlet and / or outlet of the outdoor heat exchanger 130.

[0048] During a heating operation, a circulation direction of the refrigerant is reversed, and thus the inlet of the outdoor heat exchanger 130 where the refrigerant flows in and the outlet of the outdoor heat exchanger 130 where the refrigerant flows out may be defined in reverse. However, for convenience of description, the inlet and outlet of the outdoor heat exchanger 130 may be described based on a cooling operation.

[0049] A compressor outlet temperature sensor 173 may be disposed at the outlet of the compressor 110. The compressor outlet temperature sensor 173 may detect a discharge temperature of the refrigerant discharged from the compressor 110. The discharge temperature of the refrigerant discharged from the compressor 110 may be referred to as a compressor discharge temperature or a compressor outlet temperature.

[0050] A compressor inlet pressure sensor 174 may be disposed at the inlet of the compressor 110. The compressor inlet pressure sensor 174 may detect a pressure of the refrigerant flowing into the compressor 110 from the accumulator 160. The pressure of the refrigerant flowing into the inlet of the compressor 110 may be referred to as a compressor inlet pressure.

[0051] A compressor outlet pressure sensor 175 may be disposed at the outlet of the compressor 110. The compressor outlet pressure sensor 175 may detect a pressure of the refrigerant discharged through the outlet of the compressor 110. The pressure of the refrigerant discharged through the outlet of the compressor 110 may be referred to as a compressor outlet pressure.

[0052] The indoor unit 1b may include an expansion valve 220, the indoor heat exchanger 230, and an indoor fan 250. The indoor heat exchanger 230 performs heat exchange between indoor air and the refrigerant. The indoor fan 250 may cause indoor air to flow to the indoor heat exchanger 230. A plurality of indoor fans 250 may be provided.

[0053] The expansion valve 220 may expand the refrigerant in a high-temperature and high-pressure liquid state and discharge a mixture of gaseous and liquid refrigerants of low temperature and low pressure. The expansion valve 220 may also adjust the amount of refrigerant supplied to the indoor heat exchanger 230. The expansion valve 220 decompresses the refrigerant using throttling actions. Throttling actions refer to a reduction in pressure of the refrigerant when the refrigerant passes through a narrow flow path even without heat exchange with the outside.

[0054] The expansion valve 220 may be an electronic expansion valve (EEV) capable of controlling an opening degree. The expansion valve 220 may be, for example, a thermoelectric electronic expansion valve that uses deformation of a bimetal, a thermostatic electronic expansion valve that uses volumetric expansion by heating enclosed wax, a pulse width modulation type electronic expansion valve for opening or closing a solenoid valve according to a pulse signal, or a step motor type electronic expansion valve that uses a motor to open or close the valve.

[0055] The expansion valve 220 is illustrated as being included in the indoor unit 1b, but the expansion valve 220 may also be included in the outdoor unit 1a. In addition, the expansion valve 220 may be provided in both the outdoor unit 1a and the indoor unit 1b. For example, the expansion valve 220 may be provided in the liquid pipe P1, which is a pipe forming a refrigerant flow path between the outdoor heat exchanger 130 and the indoor heat exchanger 230.

[0056] The indoor heat exchanger 230 may serve as an evaporator that evaporates low-pressure liquid refrigerant during a cooling operation, and may serve as a condenser that condenses high-pressure gaseous refrigerant during a heating operation. The indoor heat exchanger 230, like the outdoor heat exchanger 130 of the outdoor unit 1a, includes an indoor heat exchanger refrigerant pipe (not shown) through which the refrigerant passes, and an indoor heat exchanger cooling fin (not shown) for improving a heat exchange efficiency between the refrigerant and indoor air.

[0057] The indoor fan 250 may be positioned around the indoor heat exchanger 230 to blow indoor air to the indoor heat exchanger 230. The indoor heat exchanger 230 may perform heat exchange with indoor air. The indoor fan 250 may blow indoor air before heat exchange to the indoor heat exchanger 230 while simultaneously blowing the heat-exchanged air into the indoor space.

[0058] Indoor heat exchanger temperature sensors 211 and 212 may be provided on both sides (inlet and outlet) of the indoor heat exchanger 230 to detect a temperature of the indoor heat exchanger 230. The indoor heat exchanger temperature sensors 211 and 212 may be installed around the inlet and / or outlet of the indoor heat exchanger 230, or may be installed to contact the refrigerant pipe connected to the inlet and / or outlet of the indoor heat exchanger 230.

[0059] The indoor heat exchanger temperature sensors 211 and 212 may include the indoor heat exchanger inlet temperature sensor 211 and the indoor heat exchanger outlet temperature sensor 212. The indoor heat exchanger inlet temperature sensor 211 may detect an inlet temperature of the indoor heat exchanger 230, and the indoor heat exchanger outlet temperature sensor 212 may detect an outlet temperature of the indoor heat exchanger 230. The inlet of the indoor heat exchanger 230 into which the refrigerant flows and the outlet of the indoor heat exchanger 230 from which the refrigerant flows out may be defined oppositely in cooling operation and heating operation. However, for convenience of description, the inlet and outlet of the indoor heat exchanger 230 may be described based on a cooling operation.

[0060] In addition, an indoor temperature sensor 213 may be disposed in the indoor unit 1b to detect an indoor temperature. The indoor heat exchanger temperature sensors 211 and 212 and the indoor temperature sensor 213 may be implemented as at least one of a bimetallic thermometer, a thermistor thermometer, or an infrared thermometer.

[0061] The air conditioner 1 may include various temperature sensors.

[0062] FIG. 3 is a diagram illustrating example flow of refrigerant during a cooling operation of an air conditioner according to various embodiments. FIG. 4 is a diagram illustrating example flow of refrigerant during a heating operation of an air conditioner according to various embodiments.

[0063] During a cooling operation, the refrigerant may release heat from the outdoor heat exchanger 130 and absorb heat from an indoor heat exchanger 230. During a cooling operation, the refrigerant compressed in the compressor 110 may be first supplied to the outdoor heat exchanger 130 through a four-way valve 120 and then to the indoor heat exchanger 230 through an expansion valve 220. During a cooling operation, the outdoor heat exchanger 130 may operate as a condenser that condenses the refrigerant, and the indoor heat exchanger 230 may operate as an evaporator that evaporates the refrigerant.

[0064] During a cooling operation, the high-temperature and high-pressure gaseous refrigerant discharged from the compressor 110 moves to the outdoor heat exchanger 130. The liquid or near-liquid refrigerant condensed in the outdoor heat exchanger 130 is expanded and decompressed in the expansion valve 220. Two-phase refrigerant that has passed through the expansion valve 220 moves to the indoor heat exchanger 230. The refrigerant flowing into the indoor heat exchanger 230 exchanges heat with ambient air and evaporates. Accordingly, a temperature of the heat-exchanged ambient air decreases and cold air is discharged to the outside of the indoor unit 1b.

[0065] During a heating operation, the refrigerant may release heat from the indoor heat exchanger 230 and absorb heat from the outdoor heat exchanger 130. That is, during a heating operation, the refrigerant compressed in the compressor 110 may be first supplied to the indoor heat exchanger 230 through the four-way valve 120 and then to the outdoor heat exchanger 130. In this case, the indoor heat exchanger 230 may operate as a condenser that condenses the refrigerant, and the outdoor heat exchanger 130 may operate as an evaporator that evaporates the refrigerant.

[0066] During a heating operation, the high-temperature and high-pressure gaseous refrigerant discharged from the compressor 110 moves to the indoor heat exchanger 230. The high-temperature and high-pressure gaseous refrigerant passing through the indoor heat exchanger 230 exchanges heat with low-temperature and dry air. The refrigerant is condensed into a liquid or near-liquid refrigerant and releases heat, and as the air absorbs the heat, warm air is discharged to the outside of the indoor unit 1b.

[0067] FIG. 5 is a block diagram illustrating an example configuration of an air conditioner according to various embodiments. FIG. 6 is a diagram illustrating an example of low-load operation of an air conditioner according to various embodiments.

[0068] Referring to FIG. 5, the outdoor unit 1a of the air conditioner 1 may include the engine 105 for driving the compressor 110, the four-way valve 120, the coolant flow regulator 145, the outdoor fan 150, the outdoor temperature sensor 171, the outdoor heat exchanger temperature sensor 172, the compressor outlet temperature sensor 173, the compressor inlet pressure sensor 174, the compressor outlet pressure sensor 175, the exhaust gas temperature sensor 176, the coolant temperature sensor 177, a communication interface (e.g., including communication circuitry) 180, and a controller (e.g., including various circuitry) 190. The controller 190 may include a memory 192 and a processor (e.g., including processing circuitry) 191.

[0069] The controller 190 may be electrically connected to components of the outdoor unit 1a and may include various circuitry to control the operation of each component. For example, the controller 190 may control the engine 105 that drives the compressor 110, may control the coolant flow regulator 145 to regulate a flow rate of coolant, and may control the four-way valve 120 to allow a circulation direction of refrigerant to be switched. The controller 190 may control a rotation speed of the outdoor fan 150. The rotation speed of the outdoor fan 150 may be controlled according to an outdoor temperature. In addition, the controller 190 may generate a control signal to control an opening degree of the expansion valve 220 of the indoor unit 1b.

[0070] Under the control of the controller 190, the refrigerant may circulate along a refrigerant circulation flow path including the compressor 110, the four-way valve 120, the outdoor heat exchanger 130, the expansion valve 220, and the indoor heat exchanger 230. The compressor 110 may compress a gaseous refrigerant and discharge a high-temperature and high-pressure gaseous refrigerant. In addition, the compressor 110 may not operate in a blowing operation that does not require cooling or heating.

[0071] The four-way valve 120 may switch the circulation direction of the refrigerant discharged from the compressor 110 under the control of the controller 190. The four-way valve 120 guides the refrigerant compressed in the compressor 110 to the outdoor heat exchanger 130 during a cooling operation, and guides the refrigerant compressed in the compressor 110 to the indoor heat exchanger 230 during a heating operation.

[0072] The outdoor temperature sensor 171 may transmit an electrical signal corresponding to a detected outdoor temperature to the controller 190. The outdoor heat exchanger temperature sensor 172 may transmit an electrical signal corresponding to a detected inlet temperature and / or a detected outlet temperature of the outdoor heat exchanger to the controller 190.

[0073] The compressor outlet temperature sensor 173 may transmit an electrical signal corresponding to a compressor discharge temperature to the controller 190. The compressor inlet pressure sensor 174 may transmit an electrical signal corresponding to a compressor inlet pressure to the controller 190. The compressor outlet pressure sensor 175 may transmit an electrical signal corresponding to a compressor outlet pressure to the controller 190.

[0074] The exhaust gas temperature sensor 176 may transmit an electrical signal corresponding to a detected exhaust gas temperature to the controller 190. The coolant temperature sensor 177 may transmit an electrical signal corresponding to a detected coolant temperature to the controller 190.

[0075] The communication interface 180 may include various communication circuitry and communicate with the indoor unit 1b. The communication interface 180 of the outdoor unit 1a may transmit a control signal transmitted from the controller 190 to the indoor unit 1b, or may transmit a control signal transmitted from the indoor unit 1b to the controller 190. In other words, the outdoor unit 1a and the indoor unit 1b may perform bi-directional communication. The outdoor unit 1a and the indoor unit 1b may transmit or receive various signals during operation.

[0076] The memory 192 may record / store various information required for operation of the air conditioner 1. The memory 192 may store instructions, applications, data, and / or programs required for operation of the air conditioner 1. For example, the memory 192 may store programs for cooling operation, heating operation, and defrosting operation of the air conditioner 1.

[0077] The memory 192 may include volatile memory, such as static random access memory (S-RAM), dynamic random access memory (D-RAM) for temporarily storing data. In addition, the memory 192 may include non-volatile memory, such as read only memory (ROM), an erasable programmable read only memory (EPROM), electrically erasable programmable read only memory (EEPROM), and the like, for long-term data storage.

[0078] The processor 191 may include various processing circuitry and generate a control signal for controlling an operation of the air conditioner 1 based on the instructions, applications, and data stored in the memory 192. The processor 191 may include a logic circuit and an arithmetic circuit in hardware. The processor 191 may process data according to the programs and / or instructions provided from the memory 192, and generate a control signal according the processing result. The memory 192 and the processor 191 may be implemented as a single control circuit or a plurality of circuits. Thus, the processor 191 may include various processing circuitry and / or multiple processors. For example, as used herein, including the claims, the term “processor” may include various processing circuitry, including at least one processor, wherein one or more of at least one processor, individually and / or collectively in a distributed manner, may be configured to perform various functions described herein. As used herein, when “a processor”, “at least one processor”, and “one or more processors” are described as being configured to perform numerous functions, these terms cover situations, for example and without limitation, in which one processor performs some of recited functions and another processor(s) performs other of recited functions, and also situations in which a single processor may perform all recited functions. Additionally, the at least one processor may include a combination of processors performing various of the recited / disclosed functions, e.g., in a distributed manner. At least one processor may execute program instructions to achieve or perform various functions.

[0079] Some of the above-described components of the outdoor unit 1a may be omitted, or other components may be added in addition to the above-described components of the outdoor unit 1a. For example, the outdoor unit 1a may further include a control panel. The control panel may be provided on the cabinet 10 of the outdoor unit 1a. The control panel may obtain an input (e.g., a user input) related to the operation of the air conditioner 1, and may output information about the operation of the air conditioner 1. The control panel may transmit an electrical signal (voltage or current) corresponding to the user input to the controller 190. The controller 190 may control the operation of the air conditioner 1 based on the electrical signal transmitted from the control panel. The control panel may include buttons and a display.

[0080] Hereinafter, an example operation for reducing engine exhaust gas in a case where the air conditioner 1 operates at a low load is described in greater detail.

[0081] Referring to FIG. 6, it is seen that the current temperature is 25° C., the air conditioner 1 is set to a set temperature of 24° C., and the air volume is set to low. As such, a situation may occur where the air conditioner 1 operates at a low load, such as performing a heating operation when the outside temperature is relatively high, or conversely, performing a cooling operation when the outside temperature is relatively low. In addition, in a case where only some of a plurality of indoor units 1b connected to one outdoor unit 1a are operating, the air conditioner 1 may also operate at a low load.

[0082] As such, in the case of low-load operation of the air conditioner 1, a temperature of the engine 105 may not rise sufficiently, and thus a temperature of the exhaust gas generated by the engine 105 may not increase to a sufficient temperature to react with a catalyst.

[0083] Accordingly, reacting the exhaust gas generated by the engine 105 with the catalyst is required to reduce a concentration of the exhaust gas. A method to induce an active reaction with the catalyst by temporarily increasing the load of the engine 105 to increase the temperature of the exhaust gas is described below.

[0084] A condition for determining whether the air conditioner 1 is operating at a low load is described, Whether the air conditioner 1 is operating at a low load may be determined by various methods. For example, in a case where a temperature of the exhaust gas detected by the exhaust gas temperature sensor 176 is lower than a reference temperature, it may be determined that the air conditioner 1 is operating at a low load. Here, the reference temperature may be set close to the temperature at which the exhaust gas reacts most actively with the catalyst, which may be approximately 380° C. However, the above temperature is only an example, and the reference temperature may be set to various values to determine whether the air conditioner 1 is operating at a low load.

[0085] As another example, in a case where a difference between an indoor temperature and a set temperature of the air conditioner 1 is lower than a preset temperature, it may be determined that the air conditioner 1 is operating at a low load. Here, the preset temperature may be set to various values to determine whether the air conditioner 1 is operating at a low load.

[0086] In a case where a plurality of indoor units 1b are connected to a single outdoor unit 1a and fewer than a reference number of the plurality of indoor units 1b are operating, it may be determined that the air conditioner 1 is operating at a low load. The reference number may also be set to various values to determine whether the air conditioner 1 is operating at a low load.

[0087] Whether the air conditioner 1 is operating at a low load may be determined according to various conditions.

[0088] Hereinafter, a case in which the condition for determining a low-load operation of the air conditioner 1 is an exhaust gas temperature lower than the reference temperature is described.

[0089] Based on determining that the temperature of the exhaust gas is lower than the reference temperature, the controller 190 may control the engine 105 to increase an output of the engine 105. For example, the temperature of the engine 105 may be increased by increasing a load of the engine 105 by increasing a revolutions per minute (RPM) of the engine 105 to a reference RPM or higher. The reference RPM may be set to 600 RPM during a cooling operation and 700 RPM during a heating operation. However, the above reference RPMs are only an example and may be set to various values that may increase the load of the engine 105.

[0090] Increasing the output of the engine 105 described above may be applied during both cooling mode and heating mode of the air conditioner 1.

[0091] Based on determining that the temperature of the exhaust gas is lower than the reference temperature, the controller 190 may control the engine 105 to delay an ignition timing of the engine 105.

[0092] The ignition timing of the engine 105 may be predetermined according to an RPM of an engine motor. However, in the case of low-load operation of the air conditioner 1, the controller 190 may perform retard control on a reference ignition timing, and thus the temperature of the exhaust gas may rise as the ignition timing is delayed.

[0093] Delaying the ignition timing of the engine 105 described above may be applied during both cooling mode and heating mode of the air conditioner 1.

[0094] Based on determining that the temperature of the exhaust gas is lower than the reference temperature, the controller 190 may control the coolant flow regulator 145 to decrease a flow rate of coolant.

[0095] By reducing the flow rate of the coolant flowing through the engine 105, a decrease in the temperature of the engine 105 may be reduced, and thus a decrease in the temperature of the exhaust gas may also be reduced.

[0096] The coolant flow rate control may described above may consider not only the temperature of the exhaust gas detected by the exhaust gas temperature sensor 176 but also the temperature of the coolant detected by the coolant temperature sensor 177.

[0097] Regulating the flow rate of the coolant described above may be applied during both cooling mode and heating mode of the air conditioner 1.

[0098] Based on determining that the temperature of the exhaust gas is lower than the reference temperature, the controller 190 may control the outdoor fan 150 to decrease a rotation speed of the outdoor fan 150 during a cooling mode of the air conditioner 1.

[0099] As the rotation speed of the outdoor fan 150 decreases, a pressure of the refrigerant detected by the compressor outlet pressure sensor 175 increases, and thus a load of the engine 105 may increase.

[0100] To appropriately increase the load of the engine 105, the rotation speed of the outdoor fan 150 may be controlled based on a pressure of the refrigerant detected by the compressor outlet pressure sensor 175. For example, in a case where the pressure of the refrigerant detected by the compressor outlet pressure sensor 175 is lower than a reference pressure, the rotation speed of the outdoor fan 150 may decrease to allow the pressure of the refrigerant to reach or exceed the reference pressure. Here, the reference pressure may be 2.5 MPa. However, the reference pressure is only an example and may be set to various values for an appropriate load increase of the engine 105.

[0101] Decreasing the rotation speed of the outdoor fan 150 described above may be applied when the air conditioner 1 operates in a cooling mode.

[0102] According to the operation of the controller 190 of controlling the engine 105, the coolant flow regulator 145, and the outdoor fan 150, the load and temperature of the engine 105 increase, and thus the temperature of the exhaust gas generated by the engine may also increase.

[0103] The controller 190 may perform the above operations of controlling the engine 105, the coolant flow regulator 145, and the outdoor fan 150 simultaneously to increase the temperature of the exhaust gas. The controller 190 may also control the engine 105, the coolant flow regulator 145, and the outdoor fan 150 sequentially to increase the temperature of the exhaust gas more efficiently.

[0104] For example, based on the exhaust gas temperature being lower than the reference temperature, the controller 190 may first control the engine 105 and the coolant flow regulator 145 to delay the ignition timing of the engine 105 and decrease the flow rate of the coolant.

[0105] Even after controlling the engine 105 and the coolant flow regulator 145 to delay the ignition timing of the engine and decrease the flow rate of the coolant, the exhaust gas temperature may not rise sufficiently. In this case, the controller 190 may control the outdoor fan 150 to decrease the rotation speed of the outdoor fan 150.

[0106] For example, based on the exhaust gas temperature being lower than the reference temperature after the ignition timing of the engine 105 is delayed and the flow rate of the coolant is decreased, the rotation speed of the outdoor fan 150 may be decreased to increase a pressure of the refrigerant.

[0107] In a case where the exhaust gas temperature does not rise sufficiently even after decreasing the rotation speed of the outdoor fan 150, the controller 190 may control the engine 105 to increase an RPM of the engine 105.

[0108] For example, based on the exhaust gas temperature being lower than the reference temperature after the rotation speed of the outdoor fan 150 is decreased, the controller 190 may control the engine 105 to increase an RPM of the engine 105.

[0109] Due to the increase in the exhaust gas temperature, the oxidation or reduction reaction with the catalyst becomes more active, and as a result, a concentration of the exhaust gas may decrease.

[0110] For example, by reducing a concentration of nitrogen oxides, carbon monoxide, hydrocarbons, etc., which are harmful to humans and the environment, a positive effect on the environment may occur.

[0111] FIG. 7 is a flowchart illustrating an example method for controlling an air conditioner according to various embodiments.

[0112] The controller 190 may detect whether a low-load operation condition of the air conditioner 1 is satisfied (701).

[0113] As described above, whether the air conditioner 1 is operating at a low load may be determined based on whether a temperature of an exhaust gas detected by the exhaust gas temperature sensor 176 is lower than a reference temperature.

[0114] As another example, whether the air conditioner 1 is operating at a low load may be determined according to various conditions, such as in a case where a difference between an indoor temperature and a set temperature of the air conditioner 1 is lower than a preset temperature, or in a case where a plurality of indoor units 1b are connected to a single outdoor unit 1a and fewer than a reference number of the plurality of indoor units 1b are operating.

[0115] In response to the low-load operation condition of the air conditioner 1 not being satisfied (No in operation 703), the controller 190 may control the air conditioner 1 to operate normally (707).

[0116] In response to the low-load operation condition of the air conditioner 1 being satisfied (Yes in operation 703), for example, based on determining that the temperature of the exhaust gas is lower than the reference temperature, the controller 190 may control the engine 105, the coolant flow regulator 145, and the outdoor fan 150 for exhaust gas reduction control (705).

[0117] For example, the controller 190 may control the engine 105 to increase an output of the engine 105 and delay an ignition timing of the engine 105. In addition, the controller 190 may decrease a flow rate of the coolant flowing through the engine 105. The above-described control may be applied during both cooling mode and heating mode of the air conditioner 1.

[0118] When the air conditioner 1 operates in a cooling mode, the controller 190 may control the outdoor fan 150 to decrease a rotation speed of the outdoor fan 150.

[0119] According to an embodiment of the disclosure, an air conditioner may include: a compressor configured to compress a refrigerant; an engine configured to use natural gas as fuel and drive the compressor; an exhaust gas reduction device including a catalyst that reacts with exhaust gas generated by the engine; an exhaust gas temperature sensor configured to detect an exhaust gas temperature of the engine; a coolant flow regulator configured to regulate a flow rate of a coolant supplied to the engine; an outdoor heat exchanger; an outdoor fan configured to blow air to the outdoor heat exchanger; and a controller configured to control the engine, the coolant flow regulator, and the outdoor fan, wherein the controller may be configured to, based on the exhaust gas temperature being lower than a reference temperature, control the engine to delay an ignition timing of the engine and increase an output of the engine, and control the coolant flow regulator to decrease the flow rate of the coolant.

[0120] According to the disclosure, during a low-load operation of the air conditioner, the exhaust gas may be reduced by increasing the load of the engine to increase the temperature of the engine and activate the reaction between the exhaust gas and the catalyst due to the increase in the engine exhaust temperature gas.

[0121] During a cooling mode of the air conditioner, the controller may be configured to control the outdoor fan to decrease a rotation speed of the outdoor fan, based on the exhaust gas temperature being lower than the reference temperature.

[0122] The air conditioner may further include a compressor outlet pressure sensor configured to detect a pressure of the refrigerant compressed in the compressor, wherein the controller may be configured to decrease a rotation speed of the outdoor fan to allow the pressure of the refrigerant detected by the compressor outlet pressure sensor to be greater than or equal to a reference pressure.

[0123] During a cooling mode or a heating mode of the air conditioner, the controller may be configured to control the engine to delay an ignition timing of the engine and increase an output of the engine, based on the exhaust gas temperature being lower than the reference temperature.

[0124] During a cooling mode or a heating mode of the air conditioner, the controller may be configured to the coolant flow regulator to decrease the flow rate of the coolant, based on the exhaust gas temperature being lower than the reference temperature.

[0125] The various disclosed example embodiments may be implemented in the form of a recording medium that stores instructions executable by a computer. The instructions may be stored in the form of program codes, and when executed by a processor, the instructions may create a program module to perform operations of the disclosed embodiments. The recording medium may be implemented as a computer-readable recording medium.

[0126] The computer-readable recording medium may include all kinds of recording media storing instructions that can be interpreted by a computer. For example, the computer-readable recording medium may be read only memory (ROM), random access memory (RAM), a magnetic tape, a magnetic disc, a flash memory, an optical data storage device, etc.

[0127] Although various example embodiments of the disclosure have been described with reference to the accompanying drawings, one skilled in the art will appreciate that other specific modifications may be easily made without departing from the technical spirit or essential features of the disclosure. Therefore, the foregoing example embodiments should be regarded as illustrative rather than limiting in all respects.

Examples

Embodiment Construction

[0018]Various example embodiments and the terms used therein are not intended to limit the technology disclosed herein to specific forms, and the disclosure should be understood to include various modifications, equivalents, and / or alternatives to the various embodiments.

[0019]In addition, in describing the drawings, similar reference numerals may be used to designate similar elements.

[0020]In addition, terms used herein are for the purpose of describing the various example embodiments and are not intended to restrict and / or to limit the disclosure. The singular expressions herein may include plural expressions, unless the context clearly dictates otherwise. The terms “comprises”, “includes” and “has” are intended to indicate that there are features, numbers, steps, operations, elements, parts, or combinations thereof described in the disclosure, and do not exclude the presence or addition of one or more other features, numbers, steps, operations, elements, parts, or combinations th...

Claims

1. An air conditioner, comprising:a compressor configured to compress a refrigerant;an engine configured to use natural gas as fuel and drive the compressor;an exhaust gas reduction device including a catalyst configured to react with exhaust gas generated by the engine;an exhaust gas temperature sensor configured to detect an exhaust gas temperature of the engine;a coolant flow regulator configured to regulate a flow rate of a coolant supplied to the engine;an outdoor heat exchanger;an outdoor fan configured to blow air to the outdoor heat exchanger; anda controller, comprising circuitry, configured to control the engine, the coolant flow regulator, and the outdoor fan,wherein the controller is configured to:based on the exhaust gas temperature being lower than a reference temperature, control the engine to delay an ignition timing of the engine and increase a revolutions per minute (RPM) of the engine and control the coolant flow regulator to decrease the flow rate of the coolant.

2. The air conditioner of claim 1, wherein the controller is further configured to: when the air conditioner operates in a cooling mode, control the outdoor fan to decrease a rotation speed of the outdoor fan based on the exhaust gas temperature being lower than the reference temperature3. The air conditioner of claim 2, further comprising: a compressor outlet pressure sensor configured to detect a pressure of the refrigerant compressed by the compressor,wherein the controller is configured to decrease the rotation speed of the outdoor fan such that the pressure of the refrigerant detected by the compressor outlet pressure sensor becomes equal to or higher than a reference pressure.

4. The air conditioner of claim 1, wherein the controller is configured to: when the air conditioner operates in a cooling mode or a heating mode, control the engine to delay the ignition timing of the engine and increase the revolutions per minute (RPM) of the engine based on the exhaust gas temperature being lower than the reference temperature.

5. The air conditioner of claim 1, wherein the controller is configured to: when the air conditioner operates in a cooling mode or a heating mode, control the coolant flow regulator to decrease the flow rate of the coolant based on the exhaust gas temperature being lower than the reference temperature.

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