Abstract: An air conditioner 1 includes: an outdoor heat exchanger 14; an outdoor fan 12 for blowing air to the outdoor heat exchanger; an outdoor fan motor 20 that drives the outdoor fan; an outdoor fan inverter 21 that drives the outdoor fan motor; and a control unit 31 that generates a rotation-speed command voltage for controlling the rotation number of the outdoor fan motor. In addition, the control unit starts a defrost operation of the outdoor heat exchanger, based on the rotation-speed command voltage. In this manner, it is possible to achieve an outdoor device of an air conditioner in which there is no need to provide a current detecting sensor, and it is possible to detect frost formation over the heat exchanger during a heating operation and to perform a defrost operation at low costs.

Abstract: A heat exchanger includes: a gas-side port connected to piping for a gaseous refrigerant; a liquid-side port connected to piping for a liquid refrigerant; a refrigerant path that links the gas-side port to the liquid-side port; at least four heat exchange part regions that perform heat exchange between air and the refrigerant flowing through the refrigerant path; and a branching and merging part that branches and merges the refrigerant path to connect the heat exchange part regions in series between the gas-side port and the liquid-side port through the refrigerant path. The heat exchange part regions are connected to each other through the branching and merging part so as to allow the number of refrigerant paths provided in the heat exchange part region near the gas-side port to be greater than the number of refrigerant paths provided in the heat exchange part region near the liquid-side port.

Abstract: A variable refrigerant flow (VRF) system for a building includes a plurality of outdoor VRF units configured to heat or cool a refrigerant for use in heating or cooling the building and an extremum-seeking controller. The extremum-seeking controller is configured to determine a total power consumption of the plurality of outdoor VRF units, generate a pressure setpoint for the plurality of outdoor VRF units using an extremum-seeking control technique that drives the total power consumption toward an extremum, and use the pressure setpoint to operate the plurality of outdoor VRF units.

Abstract: The present invention provides a heat exchanger having a heat exchanging portion HE including a plurality of paths through which a refrigerant flows and a plurality of columns of fin plate that exchange heat between the refrigerant and air, wherein, in a case where the heat exchanging portion functions as a condenser, the refrigerant is flown from a header into the heat exchanging portion HE via the plurality of paths, every two paths of the plurality of paths merge into one single path by branching/merging pipes after the refrigerant has flown through one fin plate, before the refrigerant flows through the other fin plate so as to flow out of the heat exchanging portion HE, wherein a difference in height between the highest path and the lowest path in a vertical direction is set equal to or less than half of a height of the heat exchanging portion HE.

Abstract: A variable refrigerant flow (VRF) system for a building. The VRF system includes at least one outdoor VRF unit configured to heat or cool a refrigerant for use in heating or cooling the building. The at least one outdoor VRF unit includes a sub-cooler and a bypass expansion valve configured to control a flow of the refrigerant through the sub-cooler and an extremum-seeking controller configured to generate a sub-cooling temperature setpoint for the at least one outdoor VRF unit. The extremum-seeking controller is configured to determine a total power consumption of the at least one outdoor VRF unit, generate a sub-cooling temperature setpoint for the at least one outdoor VRF unit using an extremum-seeking control technique that drives the total power consumption toward an extremum, and use the sub-cooling temperature setpoint to operate the at least one outdoor VRF unit.

Abstract: A cooling/heating switching unit includes first to third fittings, expansion valves and expansion-valve driving sections, a housing, a heat insulating material, and a refrigerant leak detection sensor. The first and second fittings respectively connect with a high/low-pressure-gas main pipe and a low-pressure-gas main pipe, which are linked to an outdoor unit. The third fitting connects with an indoor-unit connection pipe, which is linked to indoor units. The expansion valve for high/low-pressure-gas pipe, the expansion valve for low-pressure-gas pipe, and expansion-valve driving sections selectively connect the first or second fitting with the third fitting via a refrigerant pipe to control a flow direction of refrigerant. The housing houses the refrigerant pipe. The heat insulating material fills inside of the housing to insulate the refrigerant pipe arranged inside of the housing from heat. The refrigerant leak detection sensor is installed outside of the housing to detect leaked refrigerant.

Abstract: A variable refrigerant flow (VRF) system for a building. The VRF system includes at least one outdoor VRF unit configured to heat or cool a refrigerant for use in heating or cooling the building. The at least one outdoor VRF unit includes a sub-cooler and a bypass expansion valve configured to control a flow of the refrigerant through the sub-cooler and an extremum-seeking controller configured to generate a sub-cooling temperature setpoint for the at least one outdoor VRF unit. The extremum-seeking controller is configured to determine a total power consumption of the at least one outdoor VRF unit, generate a sub-cooling temperature setpoint for the at least one outdoor VRF unit using an extremum-seeking control technique that drives the total power consumption toward an extremum, and use the sub-cooling temperature setpoint to operate the at least one outdoor VRF unit.

Abstract: A variable refrigerant flow (VRF) system for a building includes a plurality of outdoor VRF units configured to heat or cool a refrigerant for use in heating or cooling the building and an extremum-seeking controller. The extremum-seeking controller is configured to determine a total power consumption of the plurality of outdoor VRF units, generate a pressure setpoint for the plurality of outdoor VRF units using an extremum-seeking control technique that drives the total power consumption toward an extremum, and use the pressure setpoint to operate the plurality of outdoor VRF units.

Abstract: Provided is a air conditioner including high-and-low-pressure gas pipe expansion valves each of which is provided to a corresponding one of the cooling-heating switching units and adjusts feeding of high-temperature and high-pressure gas refrigerant to the corresponding indoor unit; and a refrigeration cycle controller which adjusts a valve opening degree of the high-and-low-pressure gas pipe expansion valve of the cooling-heating switching unit connected to one of the indoor units which is not in heating operation, in accordance with a determination result on excess or deficiency of refrigerant in a refrigeration cycle.

Abstract: A hot gas bypass circuit that connects a discharge side of the compressor and a portion between the heat source side heat exchanger and the expansion valve, an on-off valve that opens and closes a channel of the hot gas bypass circuit, and a control device performing control to select one of hot gas bypass defrosting and reverse cycle defrosting according to a frosting amount on the heat source side heat exchanger and perform defrosting. The control device controls to open the on-off valve of the hot gas bypass circuit such that a part of a refrigerant discharged from the compressor is supplied to the heat source side heat exchanger via the hot gas bypass circuit and, the control device switches switch the four-way valve such that the refrigerant discharged from the compressor is supplied to the heat source side heat exchanger after passing through the four-way valve.

Abstract: An air conditioner capable of detecting resonance of a casing of an outdoor or indoor unit of an air conditioner at a low cost with high accuracy is provided. An outdoor unit of the air conditioner includes: a propeller fan that blows air to a heat exchanger; a fan motor that drives the propeller fan; a current detector that detects a current value of the fan motor; a phase detector that detects the magnetic pole position of the fan motor; a fan rotation speed detector that detects the rotation speed of the fan motor; a pulsation detector that detects pulsation of the current value; and a resonance determiner that determines resonance of a system of a casing of the outdoor unit having the fan motor. If the resonance determiner determines resonance, a controller executes resonance avoidance control for increasing or decreasing the fan rotation speed by a predetermined rotation speed.

Abstract: The air conditioner has: an outdoor heat exchanger that exchanges heat between the air and a refrigerant flowing in the interior of this heat exchanger; an outdoor fan that blows air into the outdoor heat exchanger; an outdoor fan motor that rotationally drives the outdoor fan; an outdoor fan inverter that supplies a desired current to the outdoor fan motor; a current detector that detects the current flowing in the outdoor fan motor; and a control unit that controls the outdoor fan inverter such that the rotational frequency of the outdoor fan motor reaches a target rotational frequency. The control unit starts a defrosting operation of the outdoor heat exchanger on the basis of a detection value from the current detector during the heating operation.

Abstract: A heat exchanger includes: a gas-side port connected to piping for a gaseous refrigerant; a liquid-side port connected to piping for a liquid refrigerant; a refrigerant path that links the gas-side port to the liquid-side port; at least four heat exchange part regions that perform heat exchange between air and the refrigerant flowing through the refrigerant path; and a branching and merging part that branches and merges the refrigerant path to connect the heat exchange part regions in series between the gas-side port and the liquid-side port through the refrigerant path.

Abstract: Provided is a air conditioner including high-and-low-pressure gas pipe expansion valves each of which is provided to a corresponding one of the cooling-heating switching units and adjusts feeding of high-temperature and high-pressure gas refrigerant to the corresponding indoor unit; and a refrigeration cycle controller which adjusts a valve opening degree of the high-and-low-pressure gas pipe expansion valve of the cooling-heating switching unit connected to one of the indoor units which is not in heating operation, in accordance with a determination result on excess or deficiency of refrigerant in a refrigeration cycle.

Abstract: Task: To provide a high quality air conditioner with high efficiency and stability, preventing adverse effect of manufacturing variation on the refrigerant distribution. Solution: The air conditioner having an expansion valve for decompressing a refrigerant, and a heat exchanger for heat exchange between the refrigerant and air. The air conditioner includes a first linearly shaped piping that is connected to the expansion valve and vertically disposed, a branch pipe connected to the first piping for branching a refrigerant flow path into a plurality of sections, a plurality of second pipings connected to the branch pipe, and a plurality of distributors connected to the second piping for further branching the refrigerant flow path to the heat exchanger.

Abstract: An air conditioner capable of detecting resonance of a casing of an outdoor or indoor unit of an air conditioner at a low cost with high accuracy is provided. An outdoor unit of the air conditioner includes: a propeller fan that blows air to a heat exchanger; a fan motor that drives the propeller fan; a current detector that detects a current value of the fan motor; a phase detector that detects the magnetic pole position of the fan motor; a fan rotation speed detector that detects the rotation speed of the fan motor; a pulsation detector that detects pulsation of the current value; and a resonance determiner that determines resonance of a system of a casing of the outdoor unit having the fan motor. If the resonance determiner determines resonance, a controller executes resonance avoidance control for increasing or decreasing the fan rotation speed by a predetermined rotation speed.

Abstract: A cooling/heating switching unit is provided that is capable of simply and reliably detecting leak of refrigerant. The switching unit includes: first and second fittings having a high/low-pressure-gas main pipe and a low-pressure-gas main pipe connected thereto, respectively, wherein the main pipes are linked to an outdoor unit; a third fitting having an indoor-unit connection pipe connected thereto, wherein the connection pipe is linked to indoor units; an expansion valve for high/low-pressure-gas pipe, an expansion valve for low-pressure-gas pipe, and expansion-valve driving sections that selectively connect the first or second fitting with the third fitting via a refrigerant pipe to control a flow direction of refrigerant; a housing that houses the refrigerant pipe; a heat insulating material that fills inside of the housing to insulate the refrigerant pipe arranged inside of the housing from heat; and a refrigerant leak detection sensor installed outside of the housing to detect leaked refrigerant.

Abstract: An air conditioner 1 includes: an outdoor heat exchanger 14; an outdoor fan 12 for blowing air to the outdoor heat exchanger; an outdoor fan motor 20 that drives the outdoor fan; an outdoor fan inverter 21 that drives the outdoor fan motor; and a control unit 31 that generates a rotation-speed command voltage for controlling the rotation number of the outdoor fan motor. In addition, the control unit starts a defrost operation of the outdoor heat exchanger, based on the rotation-speed command voltage. In this manner, it is possible to achieve an outdoor device of an air conditioner in which there is no need to provide a current detecting sensor, and it is possible to detect frost formation over the heat exchanger during a heating operation and to perform a defrost operation at low costs.

Abstract: Provided is an air conditioner which comprises multiple outdoor units, the air conditioner being configured so that, with the use of a low cost configuration, required refrigeration machine oil is supplied to all the outdoor units through refrigerant piping and so that the air conditioner has increased reliability. An air conditioner is provided with multiple indoor units and with four outdoor units which are connected to the multiple indoor units through refrigerant piping. A line of first refrigerant piping leading from the multiple indoor units is branched into two lines of second refrigerant piping, each of the two lines of second refrigerant piping is branched into two lines of third refrigerant piping, and the four lines of third refrigerant piping are respectively connected to the four outdoor units.

Abstract: Task: To provide a high quality air conditioner with high efficiency and stability, preventing adverse effect of manufacturing variation on the refrigerant distribution. Solution: The air conditioner having an expansion valve for decompressing a refrigerant, and a heat exchanger for heat exchange between the refrigerant and air. The air conditioner includes a first Linearly shaped piping that is connected to the expansion valve and vertically disposed, a branch pipe connected to the first piping for branching a refrigerant flow path into a plurality of sections, a plurality of second pipings connected to the branch pipe, and a plurality of distributors connected to the second piping for further branching the refrigerant flow path to the heat exchanger.