JP7017182B2 - Air conditioner - Google Patents

Description

The present invention relates to a multi-type air conditioner in which a plurality of indoor units are connected to at least one outdoor unit by a refrigerant pipe.

For one outdoor unit, including an outdoor unit having a compressor and an outdoor heat exchanger, an indoor unit having an indoor heat exchanger, and an expansion valve connected corresponding to each of the indoor units. In a multi-type air conditioner in which multiple indoor units are connected in parallel by refrigerant pipes, the amount required to achieve the required capacity is achieved by adjusting the opening of the expansion valve corresponding to each indoor unit. The refrigerant is distributed to each indoor unit. In such a multi-type air conditioner, the amount of the refrigerant flowing to the indoor unit by the expansion valve may be controlled to a minimum flow rate. For example, in a state where an indoor unit during heating operation and an indoor unit during operation stop are mixed, an expansion valve corresponding to the indoor unit during operation stop is opened in order to prevent the refrigerant from accumulating in the indoor heat exchanger. The degree is set to the degree at which the refrigerant flows slightly. Further, the opening degree is set small even when the load is low and the flow rate of the refrigerant is small. When connecting an indoor unit with a large capacity, a large-diameter expansion valve is connected to secure a large flow rate at high load, but in order to realize the small flow rate as described above with a large-diameter expansion valve, It is necessary to be able to control the opening close to full closure.

In this way, in order to perform fine control according to the required refrigerant flow rate, it is necessary to be able to control the opening degree of the expansion valve to an opening close to fully closed. Conventionally, manufacturing errors and opening / closing operations of the expansion valve. In consideration of the difference between the control opening and the actual opening due to the repeated operation, normally, the region of the opening close to the fully closed is set as the fully closed pulse region and is not used in the operation control. However, when the fully closed pulse region is used for control in order to realize a small flow rate with a large-diameter expansion valve, the expansion valve may be fully closed during the operation of the air conditioner due to the above-mentioned opening error. be. If the heating operation is continued with the expansion valve fully closed, not only warm air is not generated in the interior space, but also the amount of refrigerant sucked into the compressor is insufficient, so the discharge temperature rises sharply and compression occurs. The machine will stop protecting. Once the protection is stopped, the compressor is prohibited from restarting for a predetermined time (15 to 30 minutes).

Conventionally, in order to cope with the manufacturing error of the expansion valve, the compressor is operated at a constant frequency, and the fully closed opening is detected by detecting the temperature of the indoor heat exchanger while gradually opening the opening of the expansion valve. , There is a method of setting the detected fully closed opening degree to the lower limit of the control range (for example, Patent Document 1). With this method, the opening of the expansion valve can be controlled to an opening close to fully closed, the flow rate adjustment range is wide, and the air conditioner is finely controlled using a large-diameter expansion valve that can secure a large flow rate. be able to.

However, the conventional method is performed when the operation is stopped or started, and it corresponds to the case where the expansion valve has a deviation between the control opening and the actual opening due to repeated opening and closing operations of the expansion valve during the operation. Can not.

Japanese Unexamined Patent Publication No. 11-159893

The present invention solves the above-mentioned problems by repeatedly opening and closing the expansion valve during operation by using a large-diameter expansion valve that has a wide flow rate adjustment range and can secure a large flow rate. It is an object of the present invention to provide an air conditioner capable of finely controlling the expansion valve by preventing the protection stop even when the control opening and the actual opening deviate from each other.

In order to solve the above problems, the air conditioner of the present invention includes a compressor, an outdoor heat exchanger, and a discharge temperature detecting means for detecting a discharge temperature which is the temperature of the refrigerant discharged from the compressor. A plurality of outdoor units, an indoor heat exchanger, an indoor heat exchange temperature detecting means for detecting the indoor heat exchange temperature which is the temperature of the refrigerant flowing through the indoor heat exchanger, and an indoor temperature detecting means for detecting the indoor temperature. It has an indoor unit, an expansion valve connected to each of the indoor units, a compressor, and a control unit for controlling the expansion valve, and a plurality of the indoor units are provided for one outdoor unit. The indoor unit is an air conditioner connected in parallel by a refrigerant pipe, and the control unit determines whether or not the expansion valve is fully closed when the air conditioner is operating for heating. When it is determined that the expansion valve is fully closed by the expansion valve fully closed determination, the compressor is temporarily stopped and it is determined that the expansion valve is fully closed. Initialize the expansion valve.

In the above-mentioned air conditioner, it is determined whether or not the expansion valve corresponding to the indoor unit during heating operation is fully closed, and if it is fully closed, the compressor is temporarily stopped and the expansion valve is initialized. I do. Since it is impossible for the indoor unit to be fully closed during operation in terms of control, there is a discrepancy between the control opening and the actual opening of the expansion valve by determining whether or not it is fully closed. Becomes clear. When the expansion valve is fully closed due to the deviation between the control opening and the actual opening during operation, the expansion valve 24 is initialized before the compressor is protected and stopped.

According to the air conditioner of the present invention configured as described above, the expansion valve is repeatedly opened and closed during operation by using a large-diameter expansion valve that has a wide flow rate adjustment range and can secure a large flow rate. Even if there is a discrepancy between the control opening and the actual opening of the expansion valve, it is possible to prevent the protection stop and perform fine control.

It is explanatory drawing of the air conditioner which is an embodiment of this invention, (A) is a refrigerant circuit diagram, (B) is a block diagram of an outdoor unit control means and an indoor unit control means. It is a flowchart explaining the process by the outdoor unit control means in embodiment of this invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. As an embodiment, a multi-type air conditioner in which four indoor units are connected in parallel to one outdoor unit and all the indoor units can be simultaneously cooled or heated will be described as an example. The present invention is not limited to the following embodiments, and various modifications can be made without departing from the gist of the present invention.

As shown in FIG. 1A, the air conditioner 1 in the present embodiment has one outdoor unit 2, and the outdoor unit 2 has a first liquid pipe 8a, a second liquid pipe 8b, and a third liquid pipe 8c. It includes a fourth liquid pipe 8d and four indoor units 5a to 5d connected in parallel by a gas pipe 9.

Each of the above components is connected as follows. One end of the first liquid pipe 8a is connected to the first liquid side closing valve 28a of the outdoor unit 2, and the other end is connected to the liquid side closing valve 53a of the indoor unit 5a. Further, one end of the second liquid pipe 8b is connected to the second liquid side closing valve 28b of the outdoor unit 2, and the other end is connected to the liquid side closing valve 53b of the indoor unit 5b. Further, one end of the third liquid pipe 8c is connected to the third liquid side closing valve 28c of the outdoor unit 2, and the other end is connected to the liquid side closing valve 53c of the indoor unit 5c. Further, one end of the fourth liquid pipe 8d is connected to the fourth liquid side closing valve 28d of the outdoor unit 2, and the other end is connected to the liquid side closing valve 53d of the indoor unit 5d. Further, one end of the gas pipe 9 is connected to the gas side closing valve 29 of the outdoor unit 2, and the other end is branched and connected to the gas side closing valves 54a to 54d of the indoor units 5a to 5d. In this way, the outdoor unit 2 and the indoor units 5a to 5d are connected by the first liquid pipe 8a, the second liquid pipe 8b, the third liquid pipe 8c, the fourth liquid pipe 8d, and the gas pipe 9, and the air is connected. The refrigerant circuit 10 of the harmonizer 1 is configured.

First, the outdoor unit 2 will be described with reference to FIG. 1 (A). The outdoor unit 2 includes a compressor 21, a four-way valve 22, an outdoor heat exchanger 23, a first outdoor expansion valve 24a, a second outdoor expansion valve 24b, a third outdoor expansion valve 24c, and a fourth outdoor expansion. A valve 24d, an outdoor fan 27, a first closing valve 28a having a first liquid pipe 8a connected to one end, a second closing valve 28b having a second liquid pipe 8b connected to one end, and a third liquid having one end. A third shutoff valve 28c to which the pipe 8c is connected, a fourth shutoff valve 28d to which the fourth liquid pipe 8d is connected to one end, a gas side shutoff valve 29 to which the gas pipe 9 is connected to one end, and an outdoor unit control. It is equipped with means 200. Each of these devices except the outdoor fan 27 and the outdoor unit control means 200 is connected to each other by the refrigerant pipes described in detail below to form the outdoor unit refrigerant circuit 20 forming a part of the refrigerant circuit 10. ..

The compressor 21 is a variable capacity compressor whose operating capacity can be changed by being driven by a motor (not shown) whose rotation speed is controlled by an inverter. The refrigerant discharge side of the compressor 21 is connected to the port a of the four-way valve 22, which will be described later, by a discharge pipe 41. Further, the refrigerant suction side of the compressor 21 is connected to the port c of the four-way valve 22, which will be described later, by a suction pipe 42.

The four-way valve 22 is a flow path switching means for switching the flow direction of the refrigerant, and includes four ports a, b, c, and d. The port a is connected to the refrigerant discharge side of the compressor 21 by a discharge pipe 41. The port d is connected to one of the refrigerant inlets / outlets of the outdoor heat exchanger 23 by a refrigerant pipe 43. The port c is connected to the refrigerant suction side of the compressor 21 by a suction pipe 42. The port b is connected to the gas side closing valve 29 by an outdoor unit gas pipe 44.

The outdoor heat exchanger 23 exchanges heat between the outside air taken into the inside of the outdoor unit 2 and the refrigerant from a suction port (not shown) by the rotation of the outdoor fan 27 described later. As described above, one refrigerant inlet / outlet of the outdoor heat exchanger 23 is connected to the port d of the four-way valve 22 by the refrigerant pipe 43, and one end of the outdoor unit liquid pipe 45 is connected to the other refrigerant inlet / outlet. The outdoor heat exchanger 23 functions as a condenser when the refrigerant circuit 10 is in the cooling cycle, and functions as an evaporator when the refrigerant circuit 10 is in the heating cycle.

One end of the first liquid distribution pipe a, one end of the second liquid division pipe 46b, one end of the third liquid division pipe 46c, and one end of the fourth liquid division pipe 46d are connected to the other end of the outdoor unit liquid pipe 45, respectively. Further, the other end of the first liquid branch pipe 46a is connected to the first liquid side closing valve 28a, the other end of the second liquid branch pipe 46b is connected to the second liquid side closing valve 28b, and the other end of the third liquid branch pipe 46c. Is connected to the third liquid side closing valve 28c, and the other end of the fourth liquid branch pipe 46d is connected to the fourth liquid side closing valve 28d.

The first liquid branch pipe 46a is provided with a first outdoor expansion valve 24a. Further, the second liquid branch pipe 46b is provided with a second outdoor expansion valve 24b. Further, the third liquid branch pipe 46c is provided with a third outdoor expansion valve 24c. Further, the fourth liquid branch pipe 46d is provided with a fourth outdoor expansion valve 24d.

The first outdoor expansion valve 24a, the second outdoor expansion valve 24b, the third outdoor expansion valve 24c, and the fourth outdoor expansion valve 24d are electronic expansion valves, respectively. By adjusting the opening degree of the first outdoor expansion valve 24a, the amount of refrigerant flowing through the indoor heat exchanger 51a of the indoor unit 5a, which will be described later, is adjusted. By adjusting the opening degree of the second outdoor expansion valve 24b, the amount of refrigerant flowing through the indoor heat exchanger 51b of the indoor unit 5b, which will be described later, is adjusted. By adjusting the opening degree of the third outdoor expansion valve 24c, the amount of refrigerant flowing through the indoor heat exchanger 51c of the indoor unit 5c described later is adjusted. By adjusting the opening degree of the fourth outdoor expansion valve 24d, the amount of refrigerant flowing through the indoor heat exchanger 51d of the indoor unit 5d, which will be described later, is adjusted.

The outdoor fan 27 is made of a resin material and is arranged in the vicinity of the outdoor heat exchanger 23. The outdoor fan 27 is rotated by a fan motor (not shown) to take in outside air from a suction port (not shown) into the outdoor unit 2 and exchange heat with a refrigerant in the outdoor heat exchanger 23 from an outlet (not shown) to the outdoor unit. 2 is released to the outside.

In addition to the configuration described above, the outdoor unit 2 is provided with various sensors. As shown in FIG. 1A, the discharge pipe 41 has a high pressure sensor 31 that detects the discharge pressure, which is 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 detecting the discharge temperature is provided. The suction pipe 42 includes a low pressure sensor 32 that detects the suction pressure that is the pressure of the refrigerant sucked into the compressor 21, and a suction temperature sensor 34 that detects the suction temperature that is the temperature of the refrigerant sucked into the compressor 21. Is provided. The outdoor heat exchanger 23 is provided with an outdoor heat exchange temperature sensor 35 that detects the temperature of the outdoor heat exchanger 23.

A first liquid temperature sensor 38a for detecting the temperature of the refrigerant flowing through the first liquid dividing pipe 46a between the first outdoor expansion valve 24a and the first liquid side closing valve 28a in the first liquid dividing pipe 46a is provided. Has been done. A second liquid temperature sensor 38b for detecting the temperature of the refrigerant flowing in the second liquid dividing pipe 46b between the second outdoor expansion valve 24b and the second liquid side closing valve 28b in the second liquid dividing pipe 46b is provided. Has been done. A third liquid temperature sensor 38c for detecting the temperature of the refrigerant flowing through the third liquid branch pipe 46c between the third outdoor expansion valve 24c and the third liquid side closing valve 28c is provided. A fourth liquid temperature sensor 38d for detecting the temperature of the refrigerant flowing through the fourth liquid branch pipe 46d between the fourth outdoor expansion valve 24d and the fourth liquid side closing valve 28d is provided. An outside air temperature sensor 100 for detecting the temperature of the outside air flowing into the outdoor unit 2, that is, the outside air temperature is provided in the vicinity of the suction port (not shown) of the outdoor unit 2.

Further, the outdoor unit 2 is provided with an outdoor unit control means 200. The outdoor unit control means 200 is mounted on a control board housed in an electrical component box (not shown) of the outdoor unit 2, and as shown in FIG. 1 (B), the CPU 210, the storage unit 220, and the communication unit 230. It is equipped with.

The storage unit 220 is composed of a ROM and a RAM, and stores detection values corresponding to the control program of the outdoor unit 2 and detection signals from various sensors, the control state of the compressor 21 and the outdoor fan 27, various tables described later, and the like. Remember. The communication unit 230 is an interface for communicating with the indoor units 5a to 5d.

The CPU 210 captures the detection values of various sensors, and the operation information signal including the operation start / stop signal and the operation information (set temperature, room temperature, etc.) transmitted from the indoor units 5a to 5d is transmitted via the communication unit 230. Is entered. The CPU 210 controls the opening degree of the first outdoor expansion valve 24a, the second outdoor expansion valve 24b, the third outdoor expansion valve 24c, and the fourth outdoor expansion valve 24d based on the various detected values taken in and various input information. It also controls the drive of the compressor 21 and the outdoor fan 27, and controls the switching of the four-way valve 22. Further, as shown in FIG. 1C, the CPU 210 includes a frost formation amount determining means 211, a pulse calculating means 212, and an expansion valve controlling means 213. These are used in the control described later.

Next, the four indoor units 5a to 5d will be described. Since the configurations of the indoor units 5a to 5d are all the same, in the following description, only the configuration of the indoor unit 5a will be described, and the description of the other indoor units 5b, 5c, and 5d will be omitted. Further, in FIG. 1A, the numbers assigned to the constituent devices of the indoor unit 5a are changed from a to b, c and d, respectively, and the indoor units 5b and 5c corresponding to the constituent devices of the outdoor unit 5a are obtained. It becomes a constituent device of 5d.

The indoor unit 5a includes an indoor heat exchanger 51a, a liquid side closing valve 53a to which the first liquid pipe 8a is connected, a gas side closing valve 54a to which the other end of the branched gas pipe 9 is connected, and an indoor fan. It includes 55a and indoor unit control means 500a. Each of these devices except the indoor fan 55a and the indoor unit control means 500a is connected to each other by the refrigerant pipes described in detail below to form the indoor unit refrigerant circuit 50a forming a part of the refrigerant circuit 10. ..

The indoor heat exchanger 51a exchanges heat between the indoor air taken into the indoor unit 5a and the refrigerant from a suction port (not shown) provided in the indoor unit 5a by rotating the indoor fan 55a, which will be described later. The refrigerant inlet / outlet is connected to the liquid side closing valve 53a by the indoor unit liquid pipe 71a, and the other refrigerant inlet / outlet is connected to the gas side closing valve 54a by 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.

The indoor fan 55a is a cross-flow fan made of a resin material arranged in the vicinity of the indoor heat exchanger 51a, and is rotated by a fan motor (not shown) to enter the interior of the indoor unit 5a from a suction port (not shown). The indoor air that takes in air and exchanges heat with the refrigerant in the indoor heat exchanger 51a is supplied into the room from an outlet (not shown) provided in the indoor unit 5a.

In addition to the configuration described above, the indoor unit 5a is provided with various sensors. The indoor heat exchanger 51a is provided with an indoor heat exchange temperature sensor 61a that detects the temperature of the indoor heat exchanger 51a. Further, the indoor unit gas pipe 72a is provided with a gas temperature sensor 63a. Further, an indoor temperature sensor 62a for detecting the temperature of the indoor air flowing into the indoor unit 5a, that is, the indoor temperature, is provided in the vicinity of the suction port (not shown) of the indoor unit 5a.

Further, the indoor unit 5a is provided with an indoor unit control means 500a. The control means 500a is mounted on a control board housed in an electrical component box (not shown) of the indoor unit 5a, and includes a CPU 510a, a storage unit 520a, and a communication unit 530a as shown in FIG. 1 (B). ing.

The storage unit 520a is composed of a ROM and a RAM, and stores detection values corresponding to detection signals from the indoor unit 5a control program and various sensors, setting information related to air conditioning operation by the user, and the like. The communication unit 530a is an interface for communicating with the outdoor unit 2 and other indoor units 5b and 5c.

The CPU 510a captures the detection values of various sensors, and a signal including operating conditions and timer operation settings set by the user by operating a remote controller (not shown) is input via a remote controller light receiving unit (not shown). The CPU 510a controls the drive of the indoor fan 55a based on the various detected values captured and the various input information. Further, the CPU 510a transmits an operation information signal including an operation start / stop signal and operation information (set temperature, indoor temperature, etc.) to the outdoor unit 2 via the communication unit 530a.

Next, the flow of the refrigerant and the operation of each part in the refrigerant circuit 10 during the air conditioning operation of the air conditioning device 1 in the present embodiment will be described with reference to FIG. 1 (A). In the following description, the case where the indoor units 5a to 5d perform the heating operation will be described, and the detailed description will be omitted when the indoor units 5a to 5d perform the cooling operation / defrosting operation. Further, the arrow in FIG. 1A indicates the flow of the refrigerant during the heating operation.

As shown in FIG. 1A, when the indoor units 5a to 5d perform the heating operation, that is, when the refrigerant circuit 10 is in the heating cycle, in the outdoor unit 2, the four-way valve 22 is shown by a solid line, that is, , The port a and the port b of the four-way valve 22 are switched so as to communicate with each other, and the port d and the port c are switched so as to communicate with each other. As a result, the outdoor heat exchanger 23 functions as an evaporator, and the indoor heat exchangers 51a to 51d function as a condenser.

The high-pressure refrigerant discharged from the compressor 21 flows from the discharge pipe 41 into the outdoor unit gas pipe 44 via the four-way valve 22, and flows from the outdoor unit gas pipe 44 into the gas pipe 9 via the gas side closing valve 29. do. The refrigerant flowing into the gas pipe 9 branches and flows into the indoor units 5a to 5d via the gas side closing valves 54a to 54d.

The refrigerant that has flowed into the indoor units 5a to 5d flows through the indoor unit gas pipes 72a to 72d and flows into the indoor heat exchangers 51a to 51d. The refrigerant flowing into the indoor heat exchangers 51a to 51d exchanges heat with the indoor air taken into the indoor units 5a to 5d from a suction port (not shown) due to the rotation of the indoor fans 55a to 55d to condense. In this way, the indoor heat exchangers 51a to 51d function as condensers, and the indoor heat exchangers 51a to 51d exchange heat with the refrigerant to warm the indoor air from the outlets (not shown) to the indoor units 5a to 5d. Each room is heated by blowing it into the installed room.

The refrigerant flowing out from the indoor heat exchangers 51a to 51d flows through the indoor unit liquid pipes 71a to 71d, and passes through the liquid side closing valves 53a to 53d to the first liquid pipe 8a, the second liquid pipe 8b, and the third liquid pipe 8c. And flows into the 4th liquid pipe 8d. The first liquid pipe 8a, the second liquid pipe 8b, the third liquid pipe 8c, and the fourth liquid pipe 8d to the first liquid side closing valve 28a, the second liquid side closing valve 28b, the third liquid side closing valve 28c, and The refrigerant that has flowed into the outdoor unit 2 via the fourth liquid side closing valve 28d flows through the first liquid branch pipe 46a, the second liquid branch pipe 46b, the third liquid branch pipe 46c, and the fourth liquid branch pipe 46d, and expands outside the first room. After passing through the valve 24a, the second outdoor expansion valve 24b, the third outdoor expansion valve 24c, and the fourth outdoor expansion valve 24d to reduce the pressure, the liquid flows into the outdoor unit liquid pipe 45.

The refrigerant flowing into the outdoor heat exchanger 23 from the outdoor unit liquid pipe 45 evaporates 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 outdoor heat exchanger 23 flows through the refrigerant pipe 43, flows into the four-way valve 22, flows from the four-way valve 22 to the suction pipe 42, is sucked into the compressor 21, and is compressed again.

Next, with reference to FIGS. 1 and 2, the control performed by the outdoor unit control unit 200 when the air conditioner 1 of the present embodiment determines that the expansion valve is fully closed will be described in detail.

In the following description, the indoor heat exchange temperature in the indoor heat exchangers 51a to 51d detected by the indoor heat exchange temperature sensors 61a to 61d during the heating operation is detected by the Tca to Tcd and the gas temperature sensors 63a to 63d. The heat exchange inlet temperature is Tha to Thd, the indoor temperature detected by the indoor temperature sensors 62a to 62d is Tia to Tid, and the discharge temperature detected by the discharge temperature sensor 33 is Td.

Further, the indoor heat exchange temperatures Tca to Tcd, the indoor heat exchange inlet temperatures Thea to Thd, and the indoor heat exchange temperatures Tia to Tid of the indoor heat exchangers 51a to 51d are constantly detected at predetermined time intervals (for example, 30 seconds). The detected indoor heat exchange temperatures Tca to Tcd, the indoor heat exchange inlet temperatures Tha to Thd, and the indoor temperature Tia to Tid are from the communication units 530a to 530d of the indoor unit control units 500a to 500d to the communication units of the outdoor unit control unit 200. It is stored in the storage unit 220 via 230.

The multi-type air conditioner supports indoor units that are not in operation in order to prevent refrigerant from accumulating in the indoor heat exchanger when indoor units that are in heating operation and indoor units that are not in operation are mixed. The opening degree of the expansion valve is set to such an opening degree that the refrigerant slightly flows. In addition, the opening is set small in order to throttle a large amount even when the load is low and the flow rate of the refrigerant is small.

When connecting an indoor unit with a large capacity, a large-diameter expansion valve is connected to secure a large flow rate at high load, but in order to realize the small flow rate as described above with a large-diameter expansion valve, It is necessary to be able to control the opening close to full closure.

However, in consideration of the manufacturing error of the expansion valve and the deviation between the control opening and the actual opening due to repeated opening and closing operations, the operation control usually sets the region of the opening close to fully closed as the fully closed pulse region. I tried not to use it. When the fully closed pulse region is used for control, the expansion valve may be fully closed during the operation of the air conditioner due to the above-mentioned opening error. If the heating operation is continued with the expansion valve fully closed, not only warm air is not generated in the interior space, but also the amount of refrigerant sucked into the compressor is insufficient, so the discharge temperature rises sharply and compression occurs. The machine will stop protecting. Once the protection is stopped, the compressor is prohibited from restarting for a predetermined time (15 to 30 minutes).

Therefore, in the present invention, it is determined whether or not the expansion valve 24 corresponding to the indoor unit 5 during the heating operation is fully closed, and if it is fully closed, the compressor 21 is temporarily stopped and the expansion valve 24 is fully closed. Initialize. This is because it is impossible for the indoor unit 5 to be fully closed during operation in terms of control, and it becomes clear that the expansion valve 24 has a deviation between the controlled opening degree and the actual opening degree. When the expansion valve 24 is fully closed due to the deviation between the control opening and the actual opening during operation, the expansion valve opening is opened by initializing the expansion valve 24 before the compressor 21 is protected and stopped. Can be controlled to an opening close to fully closed, the flow rate adjustment range is wide, and the air conditioner can be finely controlled by using a large-diameter expansion valve that can secure a large flow rate.

Hereinafter, the process according to the present invention will be described in detail with reference to FIG. In the flowchart shown in FIG. 2, ST represents a processing step, and the number following it represents a step number. Further, FIG. 2 mainly describes the process related to the present invention, the process when the air conditioner 1 performs a process other than the determination of the expansion valve fully closed, and the operating conditions such as the set temperature and the air volume instructed by the user. The description of general processing such as control of the refrigerant circuit 10 corresponding to the above will be omitted.

The process according to the flowchart of FIG. 2 is repeated when the refrigerant circuit 10 of the air conditioner 1 is in the heating cycle state. First, the CPU 210 has the indoor heat exchange temperatures Tca to Tcd of the indoor heat exchangers 51a to 51d detected by the indoor heat exchange temperature sensors 61a to 61d and the indoor heat exchange inlet temperatures The to Thd detected by the gas temperature sensors 63a to 63d. Then, the indoor temperatures Tia to Tid detected by the indoor temperature sensors 62a to 62d and the discharge temperature Td detected by the discharge temperature sensor 33 are read (ST10).

The CPU 210 that has completed the process of step ST10 determines whether or not the number of indoor units currently in the heating operation is a plurality of units (ST11). When the number of indoor units currently in the heating operation is a plurality of units (ST11-YES), the CPU 210 proceeds to step ST12 to determine that the expansion valve is fully closed. When the number of indoor units currently in the heating operation is one (ST11-NO), the CPU 210 proceeds to step ST13 to determine that the expansion valve is fully closed.

In the expansion valve fully closed determination in step ST12, the difference between the maximum value Thmax and the minimum value Thmin of the indoor heat exchange inlet temperature Th of the indoor heat exchanger 51 corresponding to the plurality of indoor units 5 during the heating operation detected in step ST10. It is determined whether or not (Thhmax-Thmin) is equal to or greater than the first threshold value ΔT1 (for example, 5deg), and if Thmax−Thmin ≧ ΔT1, it is determined that the expansion valve 24 is fully closed. For example, it is assumed that of the four indoor units 5a to 5d, the indoor units 5a, 5b, and 5c are in heating operation. The indoor heat exchange inlet temperature Tha of the indoor heat exchanger 51a of the indoor unit 5a, the indoor heat exchange inlet temperature Thb of the indoor heat exchanger 51b of the indoor unit 5b, and the indoor heat exchange inlet of the indoor heat exchanger 51c of the indoor unit 5c. When the temperature Thc has a relationship of Tha> Thb> Thc, the maximum value Thmax = Tha and the minimum value Thmin = Thc.

The first threshold value ΔT1 is determined in advance by a test or the like and is stored in the storage unit 220. During normal operation during heating operation (a state in which the expansion valve 24 is not fully closed), the indoor heat exchange inlet temperature Th is a temperature close to the discharge temperature Td. On the other hand, when the expansion valve 24 is fully closed, the flow of the refrigerant in the indoor heat exchanger 51 is stagnant, so that the indoor heat exchange inlet temperature Th approaches room temperature Ti. That is, the difference in the indoor heat exchange inlet temperature Th is large between the normal time and the expansion valve fully closed. Therefore, when the maximum value Thmax and the minimum value Thmin of the indoor heat exchange inlet temperature Th of the indoor unit 5 during the heating operation are compared and the difference becomes more than a predetermined value, the indoor unit 5 that detects the minimum value Thmin is used. It is determined that the corresponding expansion valve 24 is fully closed.

In the expansion valve fully closed determination in step ST13, the difference (Tc—Ti) between the indoor heat exchange temperature Tc and the indoor temperature Ti of the indoor heat exchanger 51 corresponding to the indoor unit 5 during the heating operation is the second threshold value ΔT2 (for example). It is determined whether or not the temperature is less than 4 deg) and the discharge temperature Td exceeds a predetermined temperature (for example, 100 ° C.), and Tc—Ti <ΔT2 and Td> 100 ° C. In this case, it is determined that the expansion valve 24 is fully closed.

The second threshold value ΔT2 and the predetermined temperature are determined in advance by a test or the like and stored in the storage unit 220. When there is only one indoor unit 5 during the heating operation, the expansion valve 24 of the indoor unit 5 during the heating operation is slightly opened, so that the flow of the refrigerant is stagnant. The refrigerant staying in the indoor unit 5 in which the heating operation is stopped exchanges heat with the indoor air, and the temperature gradually decreases. Therefore, the indoor heat exchange inlet temperature Th corresponding to the indoor unit 5 in which the heating operation is stopped indicates a temperature close to the indoor temperature Ti, and the same determination as "determination that the indoor units 5 in the heating operation are fully closed with a plurality of expansion valves". The method cannot be adopted. On the other hand, when the expansion valve 24 corresponding to the only indoor unit 5 during the heating operation is fully closed, the expansion valve 24 corresponding to the other stopped indoor unit 5 is slightly opened. The refrigerant hardly flows to the low pressure side (outdoor heat exchanger 23 side). If the refrigerant does not flow to the low pressure side, the amount of the refrigerant sucked into the compressor 21 decreases, so that the discharge temperature Td, which is the temperature of the refrigerant discharged from the compressor 21, rises excessively. Therefore, when the difference between the indoor heat exchange temperature Tc and the indoor temperature Ti of the indoor unit 5 during the heating operation is less than a predetermined value and the discharge temperature Td exceeds the predetermined temperature, the expansion corresponding to the indoor unit 5 during the heating operation is performed. It is determined that the valve 24 is fully closed.

When it is determined that the expansion valve 24 is fully closed in the expansion valve fully closed determination in step ST12 (ST12-YES), or when it is determined in the expansion valve fully closed determination in step ST13 that the expansion valve 24 is fully closed. If this is the case (ST13-YES), the CPU 210 stops the compressor 21 (ST14) and initializes the expansion valve 24 determined to be fully closed (ST15). In the initialization of the expansion valve 24, the opening degree of the expansion valve is once returned to the reference opening degree set to fully closed, fully opened, or in the vicinity thereof, and then to be a predetermined opening degree required at the start of operation. It is done by being controlled by. Even if the opening of the expansion valve 24 is at an arbitrary opening at the time of initialization, the opening of the expansion valve 24 is always set to the reference position (fully closed position or fully open) by subtracting or adding pulses equal to or larger than the maximum number of pulses. (Position), so the error that occurred between the cumulative number of pulses recognized by the outdoor unit control unit 200 and the actual opening of the expansion valve 24, which occurred while repeatedly opening and closing the expansion valve 24, is ensured. It can be reset and ready to start operation.

The CPU 210 that has completed the process of step ST15 restarts the compressor 21 (ST16), and ends the process according to this flowchart. When it is determined in the expansion valve fully closed determination in step ST12 that the expansion valve 24 is not fully closed (ST12-NO), or in the expansion valve fully closed determination in step ST13, the expansion valve 24 is not fully closed. If it is determined (ST13-NO), the process according to this flowchart is terminated.

As described above, in the air conditioning device 1 of the present embodiment, is the expansion valve 24 fully closed based on at least the indoor heat exchange inlet temperature Th or the indoor heat exchange temperature Tc during the heating operation? When the expansion valve fully closed determination is performed to determine whether or not the expansion valve is fully closed and it is determined by the expansion valve fully closed determination that the expansion valve 24 is fully closed, the compressor 21 is temporarily stopped and it is determined that the expansion valve 24 is fully closed. Initialization of the expanded valve 24 is performed. As a result, even when the expansion valve has a deviation between the control opening and the actual opening due to repeated opening and closing operations of the expansion valve, fine-tuned capacity control can be performed. By continuing the operation with the expansion valve fully closed, it is possible to prevent the compressor 21 from being protected and stopped.

In the present embodiment, the indoor heat exchange inlet temperature Th is detected by the gas temperature sensor 63 provided inside the indoor unit 2, but the present invention is not limited to this. For example, when the outdoor unit gas pipe 44 inside the outdoor unit 2 is branched, a gas temperature sensor 63 may be provided in each branch pipe of the outdoor unit gas pipe 44, and one extending from the outdoor unit 2. When a branch unit is provided for branching to a plurality of pipes connecting the gas pipe 9 to each indoor unit 3, a gas temperature sensor 63 may be provided for each branch pipe in the branch unit.

1 air conditioner, 2 outdoor unit, 5 indoor unit, 8 liquid pipe, 9 gas pipe, 10 refrigerant circuit, 20 outdoor unit refrigerant circuit, 21 compressor, 22 four-way valve, 23 outdoor heat exchanger, 24 outdoor expansion valve, 27 outdoor fan, 28 liquid side closing valve, 29 gas side closing valve, 31 high pressure sensor, 33 discharge temperature sensor, 34 suction temperature sensor, 35 outdoor heat exchange temperature sensor, 38 liquid temperature sensor, 41 discharge pipe, 42 suction pipe, 43 refrigerant pipes, 44 outdoor unit gas pipes, 45 outdoor unit liquid pipes, 46 liquid branch pipes, 50 indoor unit refrigerant circuits, 51 indoor heat exchangers, 53 liquid side closing valves, 54 gas side closing valves, 55 indoor fans, 61 indoors. Heat exchange temperature sensor, 62 indoor temperature sensor, 63 gas temperature sensor, 71 indoor unit liquid pipe, 72 indoor unit gas pipe, 100 outside air temperature sensor, 200 outdoor unit control means, 210 CPU, 220 storage unit, 230 communication unit, 500 indoor units. Machine control means, 510 CPU, 520 storage unit, 530 communication unit

Claims (1)

A compressor, an outdoor heat exchanger, and an outdoor unit having a discharge temperature detecting means for detecting a discharge temperature which is the temperature of the refrigerant discharged from the compressor.
An indoor heat exchanger, an indoor heat exchange temperature detecting means for detecting an indoor heat exchange temperature which is the temperature of a refrigerant flowing through the indoor heat exchanger, and a plurality of indoor units having an indoor temperature detecting means for detecting the indoor temperature. ,
Expansion valves connected to each of the plurality of indoor units,
It has the compressor and a control unit that controls the expansion valve.
An air conditioner in which a plurality of the indoor units are connected in parallel to one outdoor unit by a refrigerant pipe.
The control unit
When the air conditioner is operating for heating
An expansion valve fully closed determination is performed to determine whether or not the expansion valve is fully closed.
If it is determined by the expansion valve fully closed determination that the expansion valve is fully closed,
The compressor is temporarily stopped to initialize the expansion valve that is determined to be fully closed.
The expansion valve fully closed determination is
If only one indoor unit is operating for heating,
When the difference between the indoor temperature corresponding to the indoor unit during the heating operation and the indoor heat exchange temperature is less than a predetermined second threshold value and the discharge temperature exceeds a predetermined temperature, the indoor unit is supported. An air conditioner that determines that the expansion valve is fully closed .

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