JP2016044937A - Air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air conditioner capable of starting an air conditioning operation by rapidly changing-over a four-way valve.SOLUTION: A CPU calculates a pressure difference ΔP by taking in a high pressure Pd and a low pressure Ps and determines whether or not the pressure difference ΔP is not less than a minimum working pressure difference Pp. In the case that the pressure difference ΔP is not less than the minimum working pressure difference Pp, the CPU increases the number of revolutions of a compressor from the number of revolutions Ri at the time of excitation by an increased number of revolutions Ra. The CPU having an increased number of revolutions of the compressor starts to perform a timer measurement and determines whether or not a first prescribed time ta has elapsed after starting the timer measurement. If the first prescribed time ta has elapsed, the CPU resets a timer, inputs again the high pressure Pd and the low pressure Ps to calculate the pressure difference ΔP and determines whether or not it is not less than the minimum working pressure difference Pp. The first prescribed time ta is set specifically for a refrigerant circuit, obtained in advance by a test and the like and stored in a storage part.SELECTED DRAWING: Figure 4

Description

  The present invention relates to an air conditioner equipped with a variable capacity compressor and capable of cooling operation or heating operation by switching a four-way valve.

  The air conditioner has a refrigerant circuit in which a compressor, a four-way valve, an outdoor heat exchanger, an expansion valve, and an indoor heat exchanger are sequentially connected by refrigerant piping, and the refrigerant flow in the refrigerant circuit by switching the four-way valve Some can perform cooling operation or heating operation by switching the direction. Specifically, when performing cooling operation, connect the discharge side of the compressor to the outdoor heat exchanger, switch the four-way valve so that the outdoor heat exchanger functions as a condenser, and when performing heating operation, The suction side of the compressor is connected to the outdoor heat exchanger, and the four-way valve is switched so that the outdoor heat exchanger functions as an evaporator.

  As such a four-way valve, there is one that switches the flow direction of the refrigerant in the refrigerant circuit by operating the valve body using the pressure difference between the refrigerant pressure on the high pressure side and the refrigerant pressure on the low pressure side of the refrigerant circuit. This four-way valve has a pilot solenoid valve and a valve body that communicates or shuts off the four ports of the four-way valve. By turning on / off the energization of the pilot solenoid valve, either one of the two end portions of the valve body is provided. The valve body is operated by switching so that the high-pressure refrigerant is supplied to one side.

  Therefore, when the four-way valve is switched according to the required operation mode (cooling or heating) after starting the operation of the air conditioner, the pressure difference between the high-pressure side refrigerant pressure and the low-pressure side refrigerant pressure is determined as the four-way valve valve. There is a problem that a minimum pressure difference (hereinafter referred to as a minimum operating pressure difference) necessary for operating the body is required, and the four-way valve cannot be switched reliably unless the minimum operating pressure difference is reached.

  In order to solve the above problems, a plurality of indoor units having an indoor heat exchanger and an indoor expansion valve are connected to an outdoor unit having a compressor, a four-way valve, an outdoor heat exchanger, and an outdoor expansion valve. An air conditioner that starts energization control of the pilot solenoid valve after the compressor is started and the pressure difference between the refrigerant pressure on the high pressure side and the refrigerant pressure on the low pressure side becomes the minimum operating pressure difference. Has been proposed (for example, Patent Document 1).

JP-A-5-71822

  Generally, the lower the outside air temperature, the less the difference in pressure between the high-pressure side refrigerant pressure and the low-pressure side refrigerant pressure becomes the minimum operating pressure difference. In a multi-room air conditioner in which a plurality of indoor units are connected to one outdoor unit, an operation in which the compressor speed at startup (hereinafter referred to as startup speed) is required in the indoor unit Since it is determined based on the capacity, when the driving capacity required by the indoor unit is small, the engine is started at a low starting speed (for example, 30 rps or 40 rps). Accordingly, in this case as well, the pressure difference between the high-pressure side refrigerant pressure and the low-pressure side refrigerant pressure is unlikely to be the minimum operating pressure difference.

  In the air conditioner described in Patent Document 1, when the outside air temperature is low as described above, or when the compressor rotation speed is low, the pressure difference between the high-pressure side refrigerant pressure and the low-pressure side refrigerant pressure. There is a possibility that it takes a long time to reach the minimum operating pressure difference, and there is a problem that it takes a long time to start the air conditioning operation because the four-way valve cannot be switched for a long time.

  The present invention solves the above-described problems, and an object thereof is to provide an air conditioner that can quickly switch a four-way valve and start an air-conditioning operation.

  In order to solve the above problems, an air conditioner of the present invention includes an outdoor unit having a compressor, a four-way valve, an outdoor heat exchanger, and an outdoor expansion valve, an indoor unit having an indoor heat exchanger, and an outdoor unit. And an indoor unit having a refrigerant circuit formed by connecting a gas pipe and a liquid pipe, a high-pressure detecting means for detecting the pressure of the high-pressure refrigerant flowing through the four-way valve, and the pressure of the low-pressure refrigerant flowing through the four-way valve A low pressure detection means for detecting the pressure, a sensor input part for inputting the pressure of the high pressure refrigerant detected by the high pressure detection means and the pressure of the low pressure refrigerant detected by the low pressure detection means, a four way valve switching part for switching the four way valve, and a compressor And a control unit that controls the rotation speed and the four-way valve switching unit. The control unit calculates a pressure difference that is a difference between the pressure of the high-pressure refrigerant and the pressure of the low-pressure refrigerant taken from the sensor input unit, and the calculated pressure difference is equal to or larger than the minimum operating pressure difference necessary for switching the four-way valve. If the pressure difference is smaller than the minimum operating pressure difference, the rotational speed of the compressor is increased until the pressure difference becomes equal to or greater than the minimum operating pressure difference.

  According to the air conditioner of the present invention configured as described above, when the pressure difference between the high pressure and the low pressure is smaller than the minimum operating pressure difference at which the four-way valve switches reliably, the pressure difference becomes equal to or greater than the minimum operating pressure difference. Increase the compressor speed until. Thereby, a four-way valve can be switched quickly and an air-conditioning driving | operation can be started rapidly.

It is a refrigerant circuit figure of an air harmony device when performing heating operation in an embodiment of the present invention. It is a refrigerant circuit figure of an air harmony device when performing cooling operation in an embodiment of the present invention. It is a block diagram explaining the structure of the outdoor unit control part in embodiment of this invention. It is a flowchart explaining the process in the outdoor unit control part in embodiment of this invention.

  Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. As an embodiment, an air conditioning apparatus will be described as an example in which three indoor units are connected in parallel to one outdoor unit, and cooling operation or heating operation can be performed simultaneously in all indoor units. The present invention is not limited to the following embodiments, and can be variously modified without departing from the gist of the present invention.

  As shown in FIG. 1 and FIG. 2, an air conditioner 1 in the present embodiment is installed outdoors with one outdoor unit 2, and is installed indoors with a liquid pipe 8 and a gas pipe 9. And three indoor units 5a to 5c connected in parallel. Specifically, the liquid pipe 8 has one end connected to the closing valve 25 of the outdoor unit 2 and the other end branched to be connected to the liquid pipe connecting portions 53a to 53c of the indoor units 5a to 5c. The gas pipe 9 has one end connected to the closing valve 26 of the outdoor unit 2 and the other end branched to be connected to the gas pipe connecting portions 54a to 54c of the indoor units 5a to 5c. The refrigerant circuit 100 of the air conditioner 1 is configured as described above.

  First, the outdoor unit 2 will be described. The outdoor unit 2 includes a compressor 21, a first four-way valve 22a, a second four-way valve 22b, a first outdoor heat exchanger 23a, a second outdoor heat exchanger 23b, a first outdoor expansion valve 24a, A second outdoor expansion valve 24b, a closing valve 25 to which one end of the liquid pipe 8 is connected, a closing valve 26 to which one end of the gas pipe 9 is connected, and an outdoor fan 27 are provided. These devices other than the outdoor fan 27 are connected to each other through refrigerant pipes described in detail below to constitute an outdoor unit refrigerant circuit 20 that forms part of the refrigerant circuit 100.

  The compressor 21 is a variable capacity compressor that can vary its operating capacity by being driven by a motor (not shown) whose rotation speed is controlled by an inverter. One end of a discharge pipe 41 is connected to the refrigerant discharge side of the compressor 21, and the other end of the discharge pipe 41 is branched into a first discharge branch pipe 41a and a second discharge branch pipe 41b. The first discharge branch pipe 41a is connected to a port a of a first four-way valve 22a described later, and the second discharge branch pipe 41b is connected to a port e of a second four-way valve 22b described later.

  Further, one end of a suction pipe 42 is connected to the refrigerant suction side of the compressor 21, and the other end of the suction pipe 42 is branched into a first suction distribution pipe 42a and a second suction distribution pipe 42b. The first suction distribution pipe 42a is connected to a port c of a first four-way valve 22a described later, and the second suction distribution pipe 42b is connected to a port g of a second four-way valve 22b described later.

  The first four-way valve 22a is a valve for switching the flow direction of the refrigerant in the first outdoor heat exchanger 23a, and includes four ports a, b, c, and d. As described above, the first discharge distribution pipe 41a is connected to the port a. The port b is connected to one refrigerant inlet / outlet of the first outdoor heat exchanger 23a by the first connection pipe 43a. As described above, the first suction distribution pipe 42a is connected to the port c. One end of the first gas distribution pipe 45a is connected to the port d. The first four-way valve 22a includes a pilot solenoid valve (not shown), and a valve body that is operated by a pressure difference between the refrigerant pressure on the high pressure side and the refrigerant pressure on the low pressure side of the refrigerant circuit 100 to communicate or block between the four ports. have. Specifically, the valve body is operated by switching on and off the energization of the pilot solenoid valve so that high-pressure refrigerant flowing through the discharge pipe 41 is supplied to either one of the both ends of the valve body. By turning on the energization of the pilot solenoid valve, the valve element operates so that the port a and the port d and the port b and the port c communicate with each other, and by turning off the energization of the pilot solenoid valve, The valve body operates so that port a and port b and port c and port d communicate with each other.

  The second four-way valve 22b is a valve for switching the flow direction of the refrigerant in the second outdoor heat exchanger 23b, and includes four ports e, f, g, and h. As described above, the second discharge distribution pipe 41b is connected to the port e. The port f is connected to one refrigerant inlet / outlet of the second outdoor heat exchanger 23b through the second connection pipe 43b. As described above, the second suction branch pipe 42b is connected to the port g. One end of the second gas distribution pipe 45b is connected to the port h. The second four-way valve 22b includes a pilot solenoid valve (not shown), and a valve body that is operated by a pressure difference between the refrigerant pressure on the high pressure side and the refrigerant pressure on the low pressure side of the refrigerant circuit 100 to communicate or block the four ports. have. Specifically, the valve body is operated by switching on and off the energization of the pilot solenoid valve so that high-pressure refrigerant flowing through the discharge pipe 41 is supplied to either one of the both ends of the valve body. By turning on the energization of the pilot solenoid valve, the valve element is operated so that the port e and the port h and the port f and the port g communicate with each other, and by turning off the energization of the pilot solenoid valve, The valve body operates so that the port e and the port f and the port g and the port h communicate with each other.

  The other end of the first gas distribution pipe 45a and the other end of the second gas distribution pipe 45b are each connected to one end of the outdoor unit gas pipe 45, and the other end of the outdoor unit gas pipe 45 is connected to the closing valve 26. Yes. Further, the first four-way valve 22a and the second four-way valve 22b are configured such that the pressure of the refrigerant flowing on the high pressure side (detected by the high pressure sensor 31) and the pressure of the refrigerant flowing on the low pressure side (detected by the low pressure sensor 32) When the pressure difference is equal to or greater than a predetermined minimum operating pressure difference (for example, 0.5 MPa), the valve body is operated.

  The first outdoor heat exchanger 23a and the second outdoor heat exchanger 23b exchange heat between the refrigerant and the outside air taken into the outdoor unit 2 by the rotation of the outdoor fan 27 described later. As described above, one refrigerant inlet / outlet of the first outdoor heat exchanger 23a is connected to the port b of the first four-way valve 22a by the first connection pipe 43a, and one end of the first liquid distribution pipe 44a is connected to the other refrigerant inlet / outlet. It is connected.

Further, as described above, one refrigerant inlet / outlet of the second outdoor heat exchanger 23b is connected to the port f of the second four-way valve 22b by the second connection pipe 43b, and the other refrigerant inlet / outlet is connected to the second liquid distribution pipe 44b. One end is connected.
The other end of the first liquid distribution pipe 44a and the other end of the second liquid distribution pipe 44b are each connected to one end of the outdoor unit liquid pipe 44, and the other end of the outdoor unit liquid pipe 44 is connected to the closing valve 25. Yes.

  Each of the first outdoor expansion valve 24a and the second outdoor expansion valve 24b is an electronic expansion valve. The first outdoor expansion valve 24a is provided in the first liquid distribution pipe 44a, and the amount of refrigerant flowing into the first outdoor heat exchanger 23a or the first outdoor heat exchanger is adjusted by adjusting the opening degree thereof. The amount of refrigerant flowing out of 23a is adjusted. The second outdoor expansion valve 24b is provided in the second liquid distribution pipe 44b, and the amount of refrigerant flowing into the second outdoor heat exchanger 23b or the second outdoor heat exchanger is adjusted by adjusting the opening degree thereof. The amount of refrigerant flowing out of 23b is adjusted.

  The outdoor fan 27 is formed of a resin material, and is disposed in the vicinity of the first outdoor heat exchanger 23a and the second outdoor heat exchanger 23b. The outdoor fan 27 is rotated by a fan motor (not shown) to take outside air into the outdoor unit 2 from a suction port (not shown), and exchanges heat with the refrigerant in the first outdoor heat exchanger 23a and the second outdoor heat exchanger 23b. Outside air is discharged to the outside of the outdoor unit 2 from a blower outlet (not shown).

  In addition to the configuration described above, the outdoor unit 2 is provided with various sensors. As shown in FIGS. 1 and 2, the discharge pipe 41 includes a high-pressure sensor 31 that is a high-pressure detection unit that detects the pressure of the refrigerant discharged from the compressor 21, and the temperature of the refrigerant discharged from the compressor 21. A discharge temperature sensor 33 for detection is provided. The suction pipe 42 is provided with a low pressure sensor 32 that is a low pressure detection means for detecting the pressure of the refrigerant sucked into the compressor 21 and a suction temperature sensor 34 for detecting the temperature of the refrigerant sucked into the compressor 21. ing.

  Between the first outdoor heat exchanger 23a and the first outdoor expansion valve 44a in the first liquid distribution pipe 44a, the refrigerant flows into the first outdoor heat exchanger 23a or flows out from the first outdoor heat exchanger 23a. The 1st heat exchange temperature sensor 35a which detects the temperature of this is provided. Further, between the second outdoor heat exchanger 23b and the second outdoor expansion valve 44b in the second liquid distribution pipe 44b, the gas flows into the second outdoor heat exchanger 23b or flows out from the second outdoor heat exchanger 23b. A second heat exchange temperature sensor 35b is provided for detecting the temperature of the refrigerant to be used. An outdoor air temperature sensor 36 that detects the temperature of the outside air that flows into the outdoor unit 2, that is, the outside air temperature, is provided near the suction port (not shown) of the outdoor unit 2.

  The outdoor unit 2 includes an outdoor unit control means 200. The outdoor unit control means 200 is mounted on a control board stored in an electrical component box (not shown) of the outdoor unit 2. As shown in FIG. 3, the outdoor unit control means 200 includes a CPU 210, a storage unit 220, a communication unit 230, a sensor input unit 240, an inverter unit 250, and a four-way valve switching unit 260.

  The storage unit 220 includes a ROM and a RAM, and stores a control program for the outdoor unit 2, detection values corresponding to detection signals from various sensors, control states of the compressor 21 and the outdoor fan 27, and the like. The communication unit 230 is an interface for performing communication with the indoor units 5a to 5c. The sensor input unit 240 captures detection results from various sensors of the outdoor unit 2 and outputs them to the CPU 210. The inverter unit 250 controls the rotational speed of the compressor 21. The four-way valve switching unit 260 performs energization on / off of the pilot solenoid valve described above of the first four-way valve 22a and the second four-way valve 22b.

  CPU210 takes in the detection result in each sensor of outdoor unit 2 mentioned above via sensor input part 240. FIG. In addition, the CPU 210 takes in control signals transmitted from the indoor units 5 a to 5 c via the communication unit 230. The CPU 210 performs drive control of the compressor 21 and drive control of the outdoor fan 27 via the inverter unit 250 based on the acquired detection result and control signal. Further, the CPU 210 switches the first four-way valve 22a and the second four-way valve 22b via the four-way valve switching unit 260 based on the acquired detection result and control signal. Furthermore, the CPU 210 controls the opening degree of the first outdoor expansion valve 24a and the second outdoor expansion valve 24b based on the acquired detection result and control signal. Although not shown, the CPU 210 has a timer measurement function.

  Next, the three indoor units 5a to 5c will be described. The three indoor units 5a to 5c are respectively branched into indoor heat exchangers 51a to 51c, indoor expansion valves 52a to 52c, and liquid pipe connection portions 53a to 53c to which the other ends of the branched liquid pipes 8 are connected. Gas pipe connection portions 54a to 54c to which the other ends of the gas pipes 9 are connected are provided, and indoor fans 55a to 55c are provided. And these each apparatus except indoor fan 55a-55c is mutually connected by each refrigerant | coolant piping explained in full detail below, and comprises the indoor unit refrigerant circuit 50a-50c which makes a part of refrigerant circuit 100. FIG.

  In addition, since the structure of all the indoor units 5a-5c is the same, in the following description, only the structure of the indoor unit 5a is demonstrated and description is abbreviate | omitted about the other indoor units 5b and 5c. Moreover, in FIG. 1 and FIG. 2, what changed the end of the number provided to the component apparatus of the indoor unit 5a from a to b and c respectively is the structure of the indoor units 5b and 5c corresponding to the component apparatus of the outdoor unit 5a. It becomes a device.

The indoor heat exchanger 51a exchanges heat between the refrigerant and room air taken into the interior of the indoor unit 5a through a suction port (not shown) by rotation of an indoor fan 55a, which will be described later. The indoor unit liquid pipe 71a is connected to the section 53a, and the other refrigerant inlet / outlet is connected to the gas pipe connecting section 54a through the indoor unit gas pipe 72a. The indoor heat exchanger 51a functions as an evaporator when the indoor unit 5a performs a cooling operation, and functions as a condenser when the indoor unit 5a performs a heating operation.
Each refrigerant pipe is connected to the liquid pipe connecting portion 53a and the gas pipe connecting portion 54a by welding, a flare nut or the like.

  The indoor expansion valve 52a is provided in the indoor unit liquid pipe 71a. The indoor expansion valve 52a is an electronic expansion valve, and the amount of refrigerant flowing through the indoor heat exchanger 51a can be adjusted by adjusting the opening degree thereof. When the indoor heat exchanger 51a functions as an evaporator, the indoor expansion valve 52a is adjusted according to the required cooling capacity, and when the indoor heat exchanger 51a functions as a condenser, The opening is adjusted according to the required heating capacity.

  The indoor fan 55a is formed of a resin material and is disposed in the vicinity of the indoor heat exchanger 51a. The indoor fan 55a is rotated by a fan motor (not shown) to take indoor air into the indoor unit 5a from a suction port (not shown), and the indoor air exchanged with the refrigerant in the indoor heat exchanger 51a from the blower outlet (not shown) to the room. To supply.

  In addition to the configuration described above, the indoor unit 5a is provided with various sensors. Between the indoor heat exchanger 51a and the indoor expansion valve 52a in the indoor unit liquid pipe 71a, a liquid side temperature sensor 61a that detects the temperature of the refrigerant flowing into or out of the indoor heat exchanger 51a. Is provided. The indoor unit gas pipe 72a is provided with a gas side temperature sensor 62a that detects the temperature of the refrigerant flowing out of the indoor heat exchanger 51a or flowing into the indoor heat exchanger 51a. An indoor temperature sensor 63a that detects the temperature of the indoor air flowing into the indoor unit 5a, that is, the indoor temperature, is provided in the vicinity of a suction port (not shown) of the indoor unit 5a.

  Although illustration is omitted, an indoor unit control means is mounted on the control board stored in the electrical component box of the indoor unit 5a. The detected values detected by the liquid side temperature sensor 61a, the gas side temperature sensor 62a, and the room temperature sensor 63a are input to the indoor unit control means, and the operating conditions (settings) set by the user by operating a remote controller (not shown) A signal including temperature and air volume is input. The indoor unit control means controls the opening degree of the indoor expansion valve 52a and the drive control of the indoor fan 55a based on the inputted various information and a control signal transmitted from the outdoor unit control means 200 described later.

  Next, the refrigerant flow and the operation of each part in the refrigerant circuit 100 during operation of the air-conditioning apparatus 1 in the present embodiment will be described with reference to FIGS. 1 and 2. The air conditioner 1 according to the present embodiment can perform a heating operation for heating the room in which the indoor units 5a to 5c are installed and a cooling operation for cooling the room in which the indoor units 5a to 5c are installed. .

  In the following description, first, the operation of the air conditioner 1 during the heating operation will be described using FIG. 1, and then the operation of the air conditioner 1 during the cooling operation will be described using FIG. 2. In FIGS. 1 and 2, the arrows indicate the flow of the refrigerant in the refrigerant circuit 100. Further, the heat exchanger functioning as a condenser is hatched, and the heat exchanger functioning as an evaporator is illustrated in white.

<Heating operation>
As shown in FIG. 1, when performing heating operation, the CPU 210 of the outdoor unit control means 200 turns on the pilot solenoid valve of the first four-way valve 22a via the four-way valve switching unit 260 and turns on the first four-way valve 22a. Is indicated by a solid line, that is, the port a and the port d communicate with each other, and the port b and the port c communicate with each other. Further, the CPU 210 turns on the energization of the pilot solenoid valve of the second four-way valve 22b via the four-way valve switching unit 260, and the state indicated by the solid line of the second four-way valve 22b, that is, the port e and the port h communicate with each other. In addition, switching is performed so that the port f and the port g communicate with each other. Thereby, while the 1st outdoor heat exchanger 23a and the 2nd outdoor heat exchanger 23b function as an evaporator, the indoor heat exchangers 51a-51c function as a condenser.

  When the refrigerant circuit 100 is in the above state, the high-pressure refrigerant discharged from the compressor 21 flows through the discharge pipe 41 and is divided into the first discharge branch pipe 41a and the second discharge branch pipe 41b. The refrigerant flowing through the first discharge distribution pipe 41a flows into the first four-way valve 22a, flows from the first four-way valve 22a through the first gas distribution pipe 45a, and flows into the outdoor unit gas pipe 45. On the other hand, the refrigerant flowing through the second discharge branch pipe 41b flows into the second four-way valve 22b, flows from the second four-way valve 22b through the second gas branch pipe 45b, and flows into the outdoor unit gas pipe 45.

  The refrigerant that has flowed into the outdoor unit gas pipe 45 flows through the gas pipe 9 via the shut-off valve 26 and is divided, and then flows into the indoor units 5a to 5c through the gas pipe connection portions 54a to 54c. The refrigerant flowing into the indoor units 5a to 5c flows through the indoor unit gas pipes 72a to 72b, flows into the indoor heat exchangers 51a to 51b, and is taken into the indoor units 5a to 5c by the rotation of the indoor fans 55a to 55c. Heat exchanges with the room air and condenses. As described above, the indoor heat exchangers 51a to 51c function as condensers, and the indoor air that has exchanged heat with the refrigerant in the indoor heat exchangers 51a to 51c is blown into the room from a blowout port (not shown), thereby The room where the machines 5a to 5c are installed is heated.

  The refrigerant flowing out of the indoor heat exchangers 51a to 51c flows through the indoor unit liquid pipes 71a to 71c, passes through the indoor expansion valves 52a to 52c, and is decompressed. The decompressed refrigerant flows into the liquid pipe 8 through the liquid pipe connecting portions 53a to 53c. The refrigerant flowing through the liquid pipe 8 and flowing into the outdoor unit 2 through the shut-off valve 25 flows through the outdoor unit liquid pipe 44 and is divided into the first liquid distribution pipe 44a and the second liquid distribution pipe 44b.

  The refrigerant flowing into the first liquid distribution pipe 44a is further decompressed when passing through the first outdoor expansion valve 24a. The refrigerant flowing into the first outdoor heat exchanger 23 a from the first outdoor expansion valve 24 a evaporates by exchanging heat with the outside air taken into the outdoor unit 2 by the rotation of the outdoor fan 27. The refrigerant that has flowed out of the first outdoor heat exchanger 23a flows through the first connection pipe 43a, the first four-way valve 22a, and the first suction distribution pipe 42a, and then flows into the suction pipe 42.

  On the other hand, the refrigerant flowing into the second liquid distribution pipe 44b is further depressurized when passing through the second outdoor expansion valve 24b. The refrigerant flowing into the second outdoor heat exchanger 23b from the second outdoor expansion valve 24b evaporates by exchanging heat with the outside air taken into the outdoor unit 2 by the rotation of the outdoor fan 27. The refrigerant that has flowed out of the second outdoor heat exchanger 23b flows through the second connection pipe 43b, the second four-way valve 22b, and the second suction distribution pipe 42b and flows into the suction pipe 42. Then, the refrigerant flowing into the suction pipe 42 is sucked into the compressor 21 and compressed again.

<Cooling operation>
As shown in FIG. 2, when the cooling operation is performed, the CPU 210 of the outdoor unit control means 200 turns off the energization of the pilot solenoid valve of the first four-way valve 22a via the four-way valve switching unit 260, and the first four-way valve 22a. Are switched so that the port a and the port b communicate with each other, and the port c and the port d communicate with each other. Further, the CPU 210 turns off the energization of the pilot solenoid valve of the second four-way valve 22b via the four-way valve switching unit 260, and the state where the second four-way valve 22b is indicated by a solid line, that is, the port e and the port f communicate with each other. In addition, the port g and the port h are switched so as to communicate with each other. Thereby, while the 1st outdoor heat exchanger 23a and the 2nd outdoor heat exchanger 23b function as a condenser, the indoor heat exchangers 51a-51c function as an evaporator.

  When the refrigerant circuit 100 is in the above state, the high-pressure refrigerant discharged from the compressor 21 flows through the discharge pipe 41 and is divided into the first discharge branch pipe 41a and the second discharge branch pipe 41b. The refrigerant flowing through the first discharge branch pipe 41a flows into the first four-way valve 22a, flows from the first four-way valve 22a through the first connection pipe 43a, and flows into the first outdoor heat exchanger 23a. The refrigerant flowing into the first outdoor heat exchanger 23 a is condensed by exchanging heat with the outside air taken into the outdoor unit 2 by the rotation of the outdoor fan 27. The refrigerant flowing out from the first outdoor heat exchanger 23a flows through the first liquid distribution pipe 44a, flows into the outdoor unit liquid pipe 44 through the fully opened first outdoor expansion valve 24a, and flows through the closing valve 25 into the liquid pipe. 8 flows in.

  On the other hand, the refrigerant flowing through the second discharge branch pipe 41b flows into the second four-way valve 22b, flows from the second four-way valve 22b through the second connection pipe 43b, and flows into the second outdoor heat exchanger 23b. The refrigerant flowing into the second outdoor heat exchanger 23 b is condensed by exchanging heat with the outside air taken into the outdoor unit 2 by the rotation of the outdoor fan 27. The refrigerant flowing out of the second outdoor heat exchanger 23b flows through the second liquid distribution pipe 44b, flows into the outdoor unit liquid pipe 44 through the fully opened second outdoor expansion valve 24b, and flows through the closing valve 25 into the liquid pipe. 8 flows in.

  When the refrigerant flowing through the liquid pipe 8 is divided and flows into the indoor units 5a to 5c via the liquid pipe connecting portions 53a to 53c, the refrigerant flows through the indoor unit liquid pipes 71a to 71c and passes through the indoor expansion valves 52a to 52c. The pressure is reduced to a low-pressure refrigerant. The refrigerant flowing into the indoor heat exchangers 51a to 51c from the indoor unit liquid tubes 71a to 71c evaporates by exchanging heat with the indoor air taken into the indoor units 5a to 5c by the rotation of the indoor fans 55a to 55c. . In this way, the indoor heat exchangers 51a to 51c function as evaporators, and the indoor air that has exchanged heat with the refrigerant in the indoor heat exchangers 51a to 51c is blown into the room from a blower outlet (not shown), thereby The room where the machines 5a to 5c are installed is cooled.

  The refrigerant that has flowed out of the indoor heat exchangers 51a to 51c flows through the indoor unit gas pipes 72a to 72c and flows into the gas pipe 9 through the gas pipe connection portions 54a to 54c. The refrigerant flowing through the gas pipe 9 and flowing into the outdoor unit 2 through the shut-off valve 26 flows through the outdoor unit gas pipe 45 and is divided into the first gas distribution pipe 45a and the second gas distribution pipe 45b. The refrigerant flowing into the first gas distribution pipe 45a flows through the first four-way valve 22a and the first suction distribution pipe 42a, flows into the suction pipe 42, is sucked into the compressor 21, and is compressed again. On the other hand, the refrigerant that has flowed into the second gas distribution pipe 45b flows through the second four-way valve 22b and the second suction distribution pipe 42b, flows into the suction pipe 42, is sucked into the compressor 21, and is compressed again.

  Next, switching control of the first four-way valve 22a and the second four-way valve 22b when performing the above-described heating operation and cooling operation will be described in detail with reference to FIG. FIG. 4 is a flowchart showing a flow of processing when the CPU 210 of the outdoor unit control unit 200 performs switching control of the first four-way valve 22a and the second four-way valve 22b. ST represents a processing step. Subsequent numbers represent step numbers.

  In the following description, the refrigerant pressure detected by the high pressure sensor 31 is Pd (hereinafter referred to as high pressure Pd), the refrigerant pressure detected by the low pressure sensor 32 is Ps (hereinafter referred to as low pressure Ps), and the high pressure Pd. The pressure difference from the low pressure Ps is ΔP, the minimum operating pressure difference is Pp, the starting rotation speed of the compressor 21 is Ri, and the predetermined rising rotation speed that is the rotation speed increase value of the compressor 21 is Ra (for example, 10 rps). To do.

  When the air conditioner 1 starts operation, the CPU 210 determines whether or not the user's operation instruction is a heating operation instruction (ST1). The user operates a remote controller (not shown) provided in each indoor unit to select a desired operation mode.

  If the operation instruction is the heating operation instruction (ST1-Yes), the CPU 210 turns on the energization of each four-way valve, that is, each of the first four-way valve 22a and the second four-way valve 22b via the four-way valve switching unit 260. Energization of the pilot solenoid valve is turned on (ST2). If the operation instruction is not a heating operation instruction, that is, if it is a cooling operation (ST1-No), the CPU 210 turns off the energization of each four-way valve, that is, the first four-way valve 22a via the four-way valve switching unit 260. The energization of each pilot solenoid valve of the second four-way valve 22b is turned off (ST3). Thus, if energization to each four-way valve is turned on or off according to the heating operation instruction or the cooling operation instruction, when the pressure difference ΔP described later becomes equal to or greater than the minimum operating pressure difference Pp, The valve body is activated and each four-way valve is switched.

  After completing the process of ST2 or ST3, the CPU 210 starts up the compressor 21 at the starting rotation speed Ri (ST4), and starts timer measurement (ST5).

  Next, the CPU 210 determines whether or not the first predetermined time ta has elapsed since the start of timer measurement in ST5 (ST6). Here, the first predetermined time ta is a time for maintaining the starting rotation speed Ri after starting the compressor 21 at the starting rotation speed Ri, for example, 1 minute. By maintaining the rotation speed of the compressor 21 at the start-up rotation speed Ri for the first predetermined time ta, the state of the refrigerant circuit 100 is stabilized. The first predetermined time ta is individual for the refrigerant circuit 100, and is obtained in advance by a test or the like and stored in the storage unit 220. If the first predetermined time ta has not elapsed (ST6-No), the CPU 210 returns the process to ST6, and if the first predetermined time ta has elapsed (ST6-Yes), the CPU 210 resets the timer. (ST7).

  Next, the CPU 210 takes in the high pressure Pd detected by the high pressure sensor 31 and the low pressure Ps detected by the low pressure sensor 32 via the sensor input unit 240 (ST8), and subtracts the low pressure Ps from the taken high pressure Pd to obtain a pressure difference ΔP. Is calculated (ST9). The CPU 210 stores the taken-in high pressure Pd and low pressure Ps and the calculated pressure difference ΔP in the storage unit 220.

  Next, CPU 210 determines whether or not pressure difference ΔP is equal to or greater than minimum operating pressure difference Pp (ST10). Note that the minimum operating pressure difference Pp is individual for the refrigerant circuit 100 and is obtained in advance by a test or the like and stored in the storage unit 220.

  When the pressure difference ΔP is not equal to or greater than the minimum operating pressure difference Pp (ST10-No), the CPU 210 increases the rotational speed of the compressor 21 from the startup rotational speed Ri by an increased rotational speed Ra (for example, 10 rps) (ST14). . The CPU 210 that has increased the rotation speed of the compressor 21 starts timer measurement (ST15), and determines whether or not the second predetermined time tb that is the rotation speed maintenance time has elapsed since the timer measurement started (ST15). ST16). If the second predetermined time tb has not elapsed (ST16-No), the CPU 210 returns the process to ST16, and if the second predetermined time tb has elapsed (ST16-Yes), the CPU 210 resets the timer. (ST17), the process returns to ST8.

  The processes of ST14 to ST17 described above are processes performed when the pressure difference ΔP is not equal to or greater than the minimum operating pressure difference Pp, that is, when there is a possibility that the first four-way valve 22a or the second four-way valve 22b may not be switched. This process is repeated at intervals of the second predetermined time tb until ΔP becomes equal to or greater than the minimum operating pressure difference Pp. Accordingly, the second predetermined time tb is preferably a short time, and the high pressure Pd and the low pressure Ps detected after the rotation speed of the compressor 21 is increased (the high pressure Pd is increased and the low pressure Ps is decreased). The minimum required time (for example, 10 seconds) is preferable. Note that the second predetermined time tb is individual for the refrigerant circuit 100 and is obtained in advance by a test or the like and stored in the storage unit 220.

  In ST10, when the pressure difference ΔP is equal to or greater than the minimum operating pressure difference Pp (ST10-Yes), the CPU 210 performs normal operation control (ST11). Specifically, the CPU 210 activates the outdoor fan 27 and drives the compressor 21 at a rotational speed corresponding to the operation capacity required by the indoor units 5a to 5c, so that the first outdoor expansion valve 24a and the second outdoor outdoor unit are driven. Let the opening degree of the expansion valve 24b be a predetermined opening degree. In addition, the CPU 210 instructs the indoor units 5a to 5c via the communication unit 230 to start the indoor fans 55a to 55c and start the opening control of the indoor expansion valves 52a to 52c.

  Next, CPU 210 determines whether or not there is an operation switching instruction that is a switching instruction from the heating operation to the cooling operation or from the cooling operation to the heating operation (ST12). If there is an operation switching instruction (ST12-Yes), the CPU 210 stops the compressor 21 (ST18) and starts timer measurement (ST19). Next, CPU 210 determines whether or not a third predetermined time tc has elapsed since the start of timer measurement in ST19 (ST20). If the third predetermined time tc has not elapsed (ST20-No), the CPU 210 returns the process to ST20, and if the third predetermined time tc has elapsed (ST20-Yes), the CPU 210 resets the timer. (ST21), and the process returns to ST1.

  The processing of ST18 to 21 described above is pressure equalization processing performed so that the pressure difference ΔP is equal to or less than a predetermined value (for example, 0.05 MPa) when the operation of the air conditioner 1 is switched. Here, the third predetermined time tc is individual to the refrigerant circuit 100, and after the compressor 21 is stopped in advance by a test or the like, until the pressure difference ΔP becomes a predetermined value or less, that is, the refrigerant circuit 100 is equalized. The time required until this time is obtained and stored in the storage unit 220.

  When switching the operation of the air conditioner 1, it is necessary to switch the first four-way valve 22a and the second four-way valve 22b, but the first four-way valve 22a and the second four-way valve 22b are switched without stopping the compressor 21. If the first four-way valve 22a and the second four-way valve 22b are switched in a state where the pressure difference ΔP is large even when the compressor 21 is stopped, the operation sound of the valve bodies of the first four-way valve 22a and the second four-way valve 22b There is a possibility that the refrigerant sound flowing through the first four-way valve 22a and the second four-way valve 22b becomes loud and uncomfortable for the user. In order to prevent this, the first four-way valve 22a and the second four-way valve 22b are switched after equalizing the refrigerant circuit 100.

  If there is no operation switching instruction in ST12 (ST12-No), CPU 210 determines whether or not there is an operation stop instruction from the user (ST13). If there is no operation stop instruction (ST13-No), the CPU 210 returns the process to ST11 and continues the air conditioning operation. If there is an operation stop instruction (ST13-Yes), the CPU 210 stops the outdoor unit 2 and the indoor units 5a to 5c and ends the processing. Specifically, the CPU 210 stops the compressor 21 and the outdoor fan 27 and turns off the first four-way valve 22a and the second four-way valve 22b if they are energized, and turns off the first outdoor expansion valve 24a and the second outdoor valve 24a. The outdoor unit 2 is stopped by fully closing the outdoor expansion valve 24b. In addition, the CPU 210 instructs the indoor units 5a to 5c via the communication unit 230 to stop the indoor fans 55a to 55c and fully close the indoor expansion valves 52a to 52c.

  As described above, in the air conditioner 1 of the present invention, the pressure difference ΔP between the high pressure Pd and the low pressure Ps when the compressor 21 is started is the lowest at which the first four-way valve 22a and the second four-way valve 22b are reliably switched. When it is smaller than the operating pressure difference Pp, the rotational speed of the compressor 21 is increased by the increased rotational speed Ra every first predetermined time ta until the pressure difference ΔP becomes equal to or greater than the minimum operating pressure difference Pp. Thereby, since the pressure difference ΔP quickly becomes equal to or greater than the minimum operating pressure difference Pp, the first four-way valve 22a and the second four-way valve 22b can be switched quickly, and the air-conditioning operation can be started quickly.

  When the air conditioner 1 is performing the cooling operation, as described above, the first expansion valve 24a and the second expansion valve 24b are fully opened. At this time, the first four-way valve 22a and the second expansion valve 24b If the refrigerant circuit 100 is in the heating operation state (state shown in FIG. 1) without switching the two-way valve 22b, the refrigerant returned from the indoor units 5a to 5c to the outdoor unit 2 is not decompressed. There is a possibility that the refrigerant does not completely evaporate in the first outdoor heat exchanger 23a and the second outdoor heat exchanger 23b, and a liquid back in which liquid refrigerant is sucked into the compressor 21 may occur. However, in the air conditioner 1 of the present invention, the cooling operation is started after the pressure difference ΔP becomes equal to or greater than the minimum operating pressure difference Pp at which the first four-way valve 22a and the second four-way valve 22b are switched reliably. Occurrence can be prevented.

  In the embodiment described above, the air conditioner 1 in which three indoor units 5a to 5c are connected to one outdoor unit 2 has been described as an example. However, one indoor unit or one indoor unit is described. Four or more units may be used, and two or more outdoor units may be used. Further, the case where two outdoor heat exchangers are provided in the outdoor unit 2 has been described as an example. However, even if there is only one outdoor heat exchanger, the number of outdoor heat exchangers is three or more. There may be.

DESCRIPTION OF SYMBOLS 1 Air conditioning apparatus 2 Outdoor unit 5a-5c Indoor unit 20 Outdoor unit refrigerant circuit 20a 1st outdoor heat exchanger unit 20b 2nd outdoor heat exchanger unit 21 Compressor 22a 1st four-way valve 22b 2nd four-way valve 23a 1st outdoor Heat exchanger 23b Second outdoor heat exchanger 41 Discharge pipe 41a First discharge distribution pipe 41b Second discharge distribution pipe 42 Intake pipe 42a First intake distribution pipe 42b Second intake distribution pipe 44 Outdoor unit liquid pipe 44a First liquid distribution pipe 44b Second liquid Distribution pipe 45 Outdoor unit gas pipe 45a First gas distribution pipe 45b Second gas distribution pipe 51a to 51c Indoor heat exchanger 100 Refrigerant circuit 200 Outdoor unit control unit 210 CPU
240 Sensor input section 250 Inverter section 260 Four-way valve switching section Pd High pressure Ps Low pressure ΔP Pressure difference Pp Minimum operating pressure difference Ri Start-up rotation speed Ra Increase rotation speed ta First predetermined time tb Second predetermined time tc Third predetermined time

Claims (3)

An outdoor unit having a compressor, a four-way valve, an outdoor heat exchanger, and an outdoor expansion valve;
An indoor unit having an indoor heat exchanger;
A refrigerant circuit in which the outdoor unit and the indoor unit are connected by a gas pipe and a liquid pipe;
An air conditioner comprising:
High-pressure detection means for detecting the pressure of the high-pressure refrigerant flowing through the four-way valve;
Low pressure detecting means for detecting the pressure of the low pressure refrigerant flowing through the four-way valve;
A sensor input unit for inputting the pressure of the high-pressure refrigerant detected by the high-pressure detection means and the pressure of the low-pressure refrigerant detected by the low-pressure detection means;
A four-way valve switching unit for switching the four-way valve;
A control unit for controlling the rotation speed of the compressor and the four-way valve switching unit;
Have
The controller is
Calculates the pressure difference, which is the difference between the pressure of the high-pressure refrigerant and the pressure of the low-pressure refrigerant taken from the sensor input unit, and whether the pressure difference is greater than or equal to the minimum operating pressure difference required when switching the four-way valve Determine whether or not
When the pressure difference is smaller than the minimum operating pressure difference, the rotational speed of the compressor is increased until the pressure difference becomes equal to or greater than the minimum operating pressure difference.
An air conditioner characterized by that. The controller is
When the pressure difference is smaller than the minimum operating pressure difference, the rotation speed of the compressor is increased by a predetermined increase rotation speed,
When a predetermined rotation speed maintenance time has elapsed after the rotation speed of the compressor is increased by the increased rotation speed, the pressure of the high-pressure refrigerant and the pressure of the low-pressure refrigerant are taken in via the sensor input unit. Calculate the pressure difference,
When the calculated pressure difference is smaller than the minimum operating pressure difference, the rotational speed of the compressor is further increased by a predetermined increased rotational speed,
2. The air conditioner according to claim 1, wherein: The high-pressure detection means is a high-pressure sensor that detects a refrigerant pressure on the high-pressure side of the compressor,
The low-pressure detection means is a low-pressure sensor that detects a refrigerant pressure on a low-pressure side in the compressor.
The air conditioner according to claim 1 or 2, wherein

Images