JP7635282B2 - Air Conditioning Equipment - Google Patents

Description

An embodiment of the present invention relates to an air conditioning device.

In air conditioners where refrigerant circulates through piping between an outdoor unit and an indoor unit, refrigerant may leak from piping connections, etc. For example, in an air conditioner, various information (parameters) about the refrigeration cycle in a state (initial state) that assumes no refrigerant leakage is occurring is acquired, and the current opening of the expansion valve of the outdoor unit is predicted from the acquired information. There is a method for determining whether or not there is a refrigerant leak by assuming that the predicted opening is the appropriate value and comparing this opening with the actual opening of the expansion valve. This allows for an accurate determination of whether or not there is a refrigerant leak.

However, there are various factors that affect the accuracy of refrigerant leakage detection, and the accuracy may deteriorate depending on the environment and installation conditions, such as fluctuations in outdoor air temperature and the capacity of the indoor unit connected to the outdoor unit. In particular, with variable refrigerant flow control, which is commonly used in air conditioning systems for buildings, it is necessary to consider that the accuracy of refrigerant leakage detection may decrease due to connection of outdoor units, capacity imbalance between the outdoor unit and the indoor unit, and operation/stop of each of multiple indoor units.

Patent No. 6130921

The present invention was made based on this, and its purpose is to provide an air conditioner that can accurately detect refrigerant leaks even under various environments and installation conditions.

An air-conditioning apparatus according to one embodiment includes an outdoor unit, at least one indoor unit, and a control unit, and the outdoor unit and the indoor unit are connected by piping through which a refrigerant flows.
The outdoor unit has a compressor, an outdoor heat exchanger, an outdoor blower, a first pressure detection unit, a second pressure detection unit, and an outdoor air temperature detection unit. The compressor draws in a refrigerant, compresses it, and discharges it. The outdoor heat exchanger exchanges heat between outdoor air and the refrigerant. The outdoor blower draws in the outdoor air and blows out the air that has been heat exchanged in the outdoor heat exchanger to the outside. The first pressure detection unit detects a first pressure of the refrigerant discharged from the compressor. The second pressure detection unit detects a second pressure of the refrigerant drawn into the compressor. The outdoor air temperature detection unit detects the outdoor air temperature, which is the temperature of the air outside the room.
The indoor unit has an indoor heat exchanger, an indoor blower, and an indoor expansion valve. The indoor heat exchanger exchanges heat between indoor air and the refrigerant. The indoor blower draws in indoor air and blows out the air that has been heat exchanged in the indoor heat exchanger into the room. The indoor expansion valve is configured to be able to adjust the flow rate of the refrigerant depending on its opening degree.
The control unit controls the operation of the outdoor unit and the indoor unit.
The control unit has a refrigerant leakage detection unit that acquires an actual opening that is a current opening of the indoor expansion valve, calculates a predicted opening that is predicted as the current opening of the indoor expansion valve based at least on a rotation speed of the compressor, the first and second pressures of the refrigerant, and an opening of the indoor expansion valve on the assumption that the refrigerant is not leaking from the piping, and compares a difference between the actual opening and the predicted opening with a determination threshold that can correct a value from an initial value to detect leakage of the refrigerant from the piping.
The refrigerant leak detection unit corrects the judgment threshold by multiplying the initial value by a correction coefficient based on the outside air temperature so that the judgment threshold is larger when the outside air temperature is below the first reference temperature and above the second reference temperature than when the outside air temperature is above the first reference temperature and below a second reference temperature that is higher than the first reference temperature.
The refrigerant leakage detection unit calculates the ratio between the rated capacity of the outdoor unit and the rated capacity of the indoor unit as a capacity ratio, and corrects the judgment threshold by multiplying the initial value by a correction coefficient based on the capacity ratio so that the judgment threshold is larger when the capacity ratio is less than the first standard capacity ratio or exceeds the second standard capacity ratio than when the capacity ratio is greater than or equal to a first standard capacity ratio and less than a second standard capacity ratio that is greater than the first standard capacity ratio.

1 is a circuit diagram illustrating an air conditioning device according to an embodiment of the present invention. 5 is a diagram showing an example of a correction coefficient value depending on an outside air temperature in the air conditioning apparatus according to the embodiment. FIG. FIG. 11 is a diagram showing an example of a correction coefficient value based on a capacity ratio in the air conditioning apparatus according to the embodiment. FIG. 11 is a diagram showing an example of a correction coefficient value based on the ratio of the number of operating units in an air conditioning apparatus according to the embodiment.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a circuit diagram that shows a schematic diagram of an air conditioner 1 according to this embodiment. The air conditioner 1 can be operated in either cooling or heating mode. As shown in FIG. 1, the air conditioner 1 includes an outdoor unit 2 and an indoor unit 4 that are connected by a flow path through which a refrigerant flows, and a control unit 6 that controls the operation of the outdoor unit 2 and the indoor unit 4. FIG. 1 shows a configuration example that includes one outdoor unit 2 and one indoor unit 4. Not limited to the illustrated example, the air conditioner 1 may include multiple indoor units 4. The flow path is configured by connecting multiple pipes. These pipes include a pipe (hereinafter referred to as an outdoor side pipe) 201 that constitutes the flow path on the outdoor unit 2 side, and a pipe (hereinafter referred to as an indoor side pipe) 401 that constitutes the flow path of the indoor unit 4.

The outdoor unit 2 has as its main components a compressor 202, a first pressure detection unit 203, an outdoor heat exchanger 204, an outdoor blower 205, an outdoor expansion valve 206, a second pressure detection unit 207, an outdoor air temperature detection unit 208, and a four-way valve 209.

The compressor 202 draws in refrigerant from the suction pipe 201a, compresses it, and discharges the compressed refrigerant to the discharge pipe 201b. The suction pipe 201a and the discharge pipe 201b each constitute part of the outdoor piping 201. For example, the compressor 202 is configured with a sealed container, a rotating shaft, a compression mechanism, an electric mechanism, etc., and discharges high-temperature, high-pressure gas-phase refrigerant to the discharge pipe 201b. The compressor 202 provides the value of the rotation speed during operation to the control unit 6 via wire or wireless. One end of the discharge pipe 201b is connected to the discharge port of the compressor 202, and the other end is connected to the four-way valve 209. The four-way valve 209 guides the refrigerant discharged from the compressor 202 to the condenser.

The first pressure detection unit (hereinafter referred to as the high-pressure pressure detection unit) 203 is disposed in the discharge pipe 201b and detects the pressure of the refrigerant discharged from the compressor 202 (first pressure, hereinafter referred to as the discharge pressure), that is, the discharge pressure of the high-temperature, high-pressure gas-phase refrigerant flowing through the discharge pipe 201b. The high-pressure pressure detection unit 203 is, for example, a pressure sensor having a pressure-sensitive element disposed in the piping of the discharge pipe 201b to detect the discharge pressure. The high-pressure pressure detection unit 203 provides the detected discharge pressure value to the control unit 6 via wire or wireless communication.

The outdoor heat exchanger 204 exchanges heat between the outdoor air and the refrigerant, and functions as a condenser when the air conditioner 1 is in cooling operation, and as an evaporator when the air conditioner 1 is in heating operation. For example, during cooling operation, the refrigerant flows through the compressor 202, four-way valve 209, outdoor heat exchanger 204, outdoor expansion valve 206, and indoor unit 4 in that order, and the space to be air-conditioned is cooled. On the other hand, during heating operation, the refrigerant flows through the compressor 202, four-way valve 209, indoor unit 4, outdoor expansion valve 206, and outdoor heat exchanger 204 in that order, and the space to be air-conditioned is heated.

The outdoor blower 205 is disposed near the outdoor heat exchanger 204, draws in outdoor air (hereinafter referred to as outside air), and blows the air that has been heat exchanged in the outdoor heat exchanger 204 out to the outside. The outside air drawn in by the outdoor blower 205 is blown onto the outdoor heat exchanger 204. This allows heat exchange to take place between the outside air and the refrigerant flowing through the outdoor heat exchanger 204.

The outdoor expansion valve 206 reduces the pressure of the refrigerant (high-pressure liquid-phase refrigerant) flowing out from the outdoor heat exchanger 204 according to its opening, and changes it to a low-pressure gas-liquid two-phase refrigerant or liquid-phase refrigerant. The outdoor expansion valve 206 is a pressure reducer that adjusts the amount of refrigerant throttling by controlling the valve opening between a minimum opening and a maximum opening, and is configured as a PMV (Pulse Motor Valve) whose opening changes continuously according to the number of drive pulses supplied. The outdoor expansion valve 206 has its opening adjusted by the control unit 6, and provides the current opening (actual opening) value to the control unit 6 via a wired or wireless connection.

The second pressure detection unit (hereinafter referred to as the low-pressure pressure detection unit) 207 is disposed in the piping (part of the outdoor piping 201) between the four-way valve 209 and the gas-liquid separator (accumulator) 210 described later, and detects the pressure of the refrigerant drawn into the compressor 202. More specifically, the low-pressure pressure detection unit 207 detects the pressure (second pressure) of the low-pressure gas-liquid two-phase refrigerant that flows through the piping and is separated into gas and liquid by the gas-liquid separator 210. The low-pressure pressure detection unit 207 is, for example, a pressure sensor in which a pressure-sensitive element is disposed in the piping to detect the second pressure. The low-pressure pressure detection unit 207 provides the control unit 6 with the detected value of the second pressure via wire or wirelessly. The gas-liquid separator 210 separates the refrigerant into gas and liquid so that the compressor 202 does not compress the liquid-phase refrigerant. A suction pipe 201a is connected to the refrigerant outlet of the gas-liquid separator 210, and the refrigerant separated into gas and liquid in the gas-liquid separator 210 passes through the suction pipe 201a and is sucked into the suction port of the compressor 202.

The outdoor air temperature detection unit 208 detects the outdoor air temperature, which is the temperature of the air outside. Here, the outdoor air is the outdoor air as opposed to the indoor air, which is the space to be air-conditioned, and is, for example, an outdoor space in which the outdoor heat exchanger 204 and the outdoor blower 205 are installed. The outdoor air temperature detection unit 208 is, for example, a temperature sensor (thermistor) having a temperature sensor disposed near the outdoor heat exchanger 204 to detect the outdoor air temperature. The outdoor air temperature detection unit 208 provides the detected outdoor air temperature value to the control unit 6 via wired or wireless communication.

The four-way valve 209 guides the refrigerant discharged from the compressor 202 to the condenser, that is, the outdoor heat exchanger 204 during cooling, and to the indoor heat exchanger 402 of the indoor unit 4 described below during heating. The four-way valve 209 also guides the refrigerant returning to the compressor 202 from the evaporator, that is, the indoor heat exchanger 402 during cooling, and the outdoor heat exchanger 204 during heating, to the accumulator 210.

The indoor unit 4 has as its main components an indoor heat exchanger 402, an indoor blower 403, an indoor expansion valve 404, etc.

The indoor heat exchanger 402 exchanges heat between the indoor air and the refrigerant, and functions as an evaporator when the air conditioner 1 is in cooling operation, and functions as a condenser when the air conditioner 1 is in heating operation. For example, during cooling operation, the refrigerant flows through the compressor 202, four-way valve 209, outdoor heat exchanger 204, outdoor expansion valve 206, indoor heat exchanger 402, and indoor expansion valve 404 in this order, and the space to be air-conditioned is cooled. On the other hand, during heating operation, the refrigerant flows through the compressor 202, four-way valve 209, indoor expansion valve 404, indoor heat exchanger 402, outdoor expansion valve 206, and outdoor heat exchanger 204 in this order, and the space to be air-conditioned is heated.

The indoor blower 403 is disposed near the indoor heat exchanger 402, sucks in the air in the room to be conditioned (hereinafter referred to as indoor air), and blows the air that has been heat exchanged in the indoor heat exchanger 402 out into the room. The indoor air sucked in by the indoor blower 403 is blown onto the indoor heat exchanger 402. This allows heat exchange to take place between the indoor air and the refrigerant flowing through the indoor heat exchanger 402.

The indoor expansion valve 404 is a regulating valve capable of adjusting the flow rate of the refrigerant according to its opening. That is, the indoor expansion valve 404 adjusts the flow rate of the refrigerant flowing out of the indoor heat exchanger 402 during cooling, and adjusts the flow rate of the refrigerant flowing into the indoor heat exchanger 402 during heating. The indoor expansion valve 404 is a pressure reducer that adjusts the amount of refrigerant throttling by controlling the opening of the valve between a minimum opening and a maximum opening, for example, and is configured as a PMV (Pulse Motor Valve) whose opening changes continuously according to the number of drive pulses supplied. The opening of the indoor expansion valve 404 is adjusted by the control unit 6, and the current opening (actual opening) value is provided to the control unit 6 via a wired or wireless connection.

The control unit 6 controls the operation of the outdoor unit 2 and the indoor unit 4, and controls the operation of the air conditioner 1. The control unit 6 includes a CPU, memory, a storage device (non-volatile memory), an input/output circuit, a timer, and the like, and executes predetermined arithmetic processing. For example, the control unit 6 reads various data through the input/output circuit, performs arithmetic processing with the CPU using a program read from the storage device to the memory, and controls the operation of the compressor 202, the high pressure detection unit 203, the outdoor expansion valve 206, the low pressure detection unit 207, the outdoor air temperature detection unit 208, and the indoor expansion valve 404 based on the processing results. At that time, the control unit 6 transmits and receives control signals and data signals between them via wires or wirelessly. In other words, the control unit 6 and each of the components to be controlled are electrically connected via wires or wirelessly.

In this embodiment, the control unit 6 has a refrigerant leakage detection unit 601 that detects leakage of refrigerant from the pipes (outdoor pipe 201 and indoor pipe 401) that form the flow path through which the refrigerant flows. The refrigerant leakage detection unit 601 is configured as a program that causes the CPU to execute a predetermined calculation process for detecting refrigerant leakage, for example, and is stored in the storage device of the control unit 6 and read into the memory during execution.

To detect a refrigerant leak, the refrigerant leak detection unit 601 acquires the actual opening degree of the indoor expansion valve 404 and calculates the predicted opening degree of the indoor expansion valve 404.

The actual opening of the indoor expansion valve 404 is the current opening of the indoor expansion valve 404, that is, the actual opening at that time. The refrigerant leakage detection unit 601 acquires the value of the actual opening from the indoor expansion valve 404. The acquired value of the actual opening is stored in the memory of the control unit 6.

The predicted opening is the opening predicted as the current opening (actual opening) of the indoor expansion valve 404, that is, the predicted value of the actual opening, and is calculated using a predetermined parameter. The predetermined parameters are various values in the case where it is assumed that the refrigerant is not leaking from the piping (the outdoor piping 201 and the indoor piping 401) (hereinafter referred to as the proper state). In this embodiment, for example, the following values in the proper state, specifically, the rotation speed of the compressor 202 in the proper state, the first pressure (discharge pressure) and the second pressure of the refrigerant, and the opening of the indoor expansion valve 404 are at least used as parameters. In other words, the predicted opening is the opening that the indoor expansion valve 404 should reach during the current operation of the air conditioning device 1 in the proper state (assuming that the refrigerant is not leaking). The calculated predicted opening value is stored in the storage device (non-volatile memory) of the control unit 6, in the predicted opening storage unit 602 in the example shown in FIG. 1. The predicted opening value stored in the predicted opening memory unit 602 is read into the memory of the control unit 6 as a parameter when determining whether or not there is a refrigerant leak.

The proper state is a state in which the air conditioning device 1 starts operation, and after the cumulative time from the start exceeds a predetermined time, a predetermined condition is satisfied, and it is an initial state that assumes that no refrigerant is leaking from the pipes (outdoor pipe 201 and indoor pipe 401). The predetermined time can be set arbitrarily depending on the environment in which the air conditioning device 1 is installed, and is, for example, about 10 to 50 hours. The predetermined conditions may include, for example, that the degree of superheat (SH: Super Heat) is proper, that the outside air temperature is not extremely outside the operating range, and that the rotation speed of the compressor 202 is not extremely low, so that each state of the refrigeration cycle in the air conditioning device 1 can be appropriately determined.

The refrigerant leakage detection unit 601 acquires the value of the rotation speed of the compressor 202 in the proper state from the compressor 202. The refrigerant leakage detection unit 601 acquires the value of the first pressure (discharge pressure) of the refrigerant in the proper state from the high pressure detection unit 203. The refrigerant leakage detection unit 601 acquires the value of the second pressure of the refrigerant in the proper state from the low pressure detection unit 207. Note that, as a parameter of the predicted opening degree, the values (detection values) acquired from the high pressure detection unit 203 and the low pressure detection unit 207, that is, the temperature values, rather than the pressure values, may be used. In this case, it is possible to calculate the saturation temperature from the values (detection values) acquired from the high pressure detection unit 203 and the low pressure detection unit 207, and use the calculated saturation temperature as a parameter. The refrigerant leakage detection unit 601 acquires the value of the opening degree of the indoor expansion valve 404 in the proper state from the indoor expansion valve 404. The acquired values of the compressor 202 rotation speed, the first pressure (discharge pressure) and second pressure of the refrigerant, and the opening degree of the indoor expansion valve 404 are stored in the memory of the control unit 6.

For example, when the air conditioning device 1 has multiple indoor units 4, the refrigerant leakage detection unit 601 calculates the predicted opening as the sum of the predicted values of the actual openings of the indoor expansion valves 404 in each indoor unit 4, i.e., the multiple indoor expansion valves 404. However, in this case, the predicted opening may also be calculated as the average value of the predicted values of the actual openings of the multiple indoor expansion valves 404.

The refrigerant leakage detection unit 601 detects refrigerant leakage by comparing the difference between the actual opening and the predicted opening of the indoor expansion valve 404 with a predetermined judgment threshold. The judgment threshold is a threshold for judging whether or not refrigerant is leaking from the piping (the outdoor piping 201 and the indoor piping 401), and in this embodiment, it is a value before correction described later, that is, an initial value. The judgment threshold may be a fixed value set in advance, or a variable value that varies depending on the judgment of the presence or absence of refrigerant leakage. The judgment threshold is held, for example, in the memory of the control unit 6, or stored in a storage device (non-volatile memory), and is used as a parameter when judging the presence or absence of refrigerant leakage. For example, when the air conditioning device 1 has multiple indoor units 4 and the predicted opening is calculated as the sum of the predicted values of the actual openings of each of the multiple indoor expansion valves 404, the actual opening when calculating the difference is the sum of the actual openings of each of the multiple indoor expansion valves 404.

When detecting a refrigerant leak, the refrigerant leak detection unit 601 corrects the judgment threshold value according to a predetermined coefficient (hereinafter referred to as the correction coefficient). The correction coefficient is a value determined by various requirements in the proper state. For example, the outdoor air temperature in the proper state can be used as the correction coefficient. In addition to this, for example, the capacity ratio of the indoor unit 4 to the outdoor unit 2 (hereinafter simply referred to as the capacity ratio), the ratio of the number of indoor units 4 in operation when multiple indoor units 4 are provided (hereinafter simply referred to as the operation number ratio), etc. can be applied as the correction coefficient, and in all cases, the detection value in the proper state is used. These correction coefficients are only examples, and in addition to the outdoor air temperature, capacity ratio, and operation number ratio in the proper state, it is possible to add a value determined by any requirement as a correction coefficient.

The outdoor air temperature is the temperature of the air in an outdoor space where the outdoor heat exchanger 204 and the outdoor blower 205 are installed, as described above, and is detected by the outdoor air temperature detection unit 208. The refrigerant leakage detection unit 601 obtains the value of the outdoor air temperature in an appropriate state from the outdoor air temperature detection unit 208. The obtained value of the outdoor air temperature is stored in the memory of the control unit 6.

The capacity ratio is the ratio between the capacity value of the outdoor unit 2 and the capacity value of the indoor unit 4 equipped in the air conditioning apparatus 1. The capacity value is the rated capacity of heating and cooling expressed in kilowatts (kW), for example, and when there are multiple indoor units 4, it is the total value of the rated capacities of each. The refrigerant leak detection unit 601 calculates the capacity ratio based on the capacity value of the outdoor unit 2 and the capacity value of the indoor unit 4 in an appropriate state. The calculated capacity ratio value is stored in the memory of the control unit 6.

When multiple indoor units 4 are provided, the ratio of the number of indoor units 4 in operation is the ratio of the number of indoor units 4 in operation to the total number of indoor units 4. Whether an indoor unit 4 is in operation can be determined based on any condition, such as whether the indoor expansion valve 404 is open or not, or whether a user has selected operation via the indoor unit 4 remote control or the like. The refrigerant leak detection unit 601 calculates the ratio of the number of operating units based on the number of indoor units 4 in operation in the appropriate state. The calculated value of the ratio of the number of operating units is stored in the memory of the control unit 6.

The refrigerant leakage detection unit 601 detects refrigerant leakage based on the actual opening degree, predicted opening degree, and correction coefficient of the indoor expansion valve 404. When performing such detection, the refrigerant leakage detection unit 601 calculates the following equation (1).
(Actual opening) - (Predicted opening) > α x W x X x Y x Z ... (1)
In formula (1), the actual opening is the actual opening value of the indoor expansion valve 404 at the time of calculation of formula (1). The predicted opening is the predicted opening value stored in the predicted opening storage unit 602. α is the value of the judgment threshold, more precisely, the value of the judgment threshold before correction (initial value of the judgment threshold). W is the value of the correction coefficient by the input unit. X is the correction coefficient by the outdoor air temperature. Y is the value of the correction coefficient by the capacity ratio. Z is the value of the correction coefficient by the ratio of the number of operating units. The input unit inputs the correction coefficient for correcting the judgment threshold and gives it to the refrigerant leakage detection unit 601. In the example shown in FIG. 1, the input unit 603 is configured as any external input means capable of switching, operating, setting, etc. in the control unit 6, such as a switch on a control board. However, the location of the input unit 603 is not particularly limited, and may be configured as an external input means such as an operation panel of the outdoor unit 2 or a remote control of the indoor unit 4.

When formula (1) is satisfied, the refrigerant leakage detection unit 601 determines that refrigerant is leaking from the piping (outdoor piping 201 and indoor piping 401). As a result, refrigerant leakage is detected based on the actual opening degree, predicted opening degree, and correction coefficient of the indoor expansion valve 404. On the other hand, when formula (1) is not satisfied, the refrigerant leakage detection unit 601 determines that refrigerant is not leaking from the piping (outdoor piping 201 and indoor piping 401). In this case, it is detected that refrigerant is not leaking based on the actual opening degree, predicted opening degree, and correction coefficient of the indoor expansion valve 404.

The correction coefficient for the outside air temperature indicated by X in formula (1) will now be described. FIG. 2 is a diagram showing an example of the value of the correction coefficient for the outside air temperature. The values of the correction coefficient for the outside air temperature are stored in the storage device (non-volatile memory) of the control unit 6 in a table format as shown in FIG. 2, for example, or in the correction coefficient storage unit 604 in the example shown in FIG. 1. However, the storage format is not limited to this. Each value of the correction coefficient for the outside air temperature stored in the correction coefficient storage unit 604 is read into the memory of the control unit 6 as a parameter for correcting the determination threshold when determining whether or not there is a refrigerant leak.

In the example shown in FIG. 2, the value (X) of the correction coefficient for the outside air temperature (Tx) is set by two thresholds, a first reference temperature (Tx1) and a second reference temperature (Tx2). The second reference temperature is greater than the first reference temperature. As a result, the outside air temperature is divided into three temperature ranges: high, medium, and low. The value of the correction coefficient for the outside air temperature is set smaller when the outside air temperature is in a standard state than when the outside air temperature is in a non-standard state. In the example shown in FIG. 2, the standard state of the outside air temperature is when the outside air temperature is equal to or greater than the first reference temperature and equal to or less than the second reference temperature (Tx1≦Tx≦Tx2). That is, the correction coefficient when the outside air temperature is equal to or greater than the first reference temperature and equal to or less than the second reference temperature is set smaller than both the correction coefficient when the outside air temperature is less than the first reference temperature (Tx<Tx1) and the correction coefficient when the outside air temperature exceeds the second reference temperature (Tx2<Tx) (the relationship is shown as "large" and "small" in FIG. 2).

Therefore, the refrigerant leakage detection unit 601 corrects the judgment threshold according to the correction coefficient for the outdoor air temperature so that the judgment threshold is larger when the outdoor air temperature is less than the first reference temperature and exceeds the second reference temperature than when the outdoor air temperature is equal to or greater than the first reference temperature and equal to or less than the second reference temperature. The first reference temperature and the second reference temperature may be set to include a temperature range of about 35°C for the standard outdoor air temperature when the air conditioning device 1 is in cooling operation, and about 7°C for the standard outdoor air temperature when the air conditioning device 1 is in heating operation. The correction coefficient for the outdoor air temperature may be set to be larger the further the outdoor air temperature deviates from the standard state. The number of thresholds (reference temperatures) for classifying the outdoor air temperature may be three or more, or may be one. If the number of thresholds (reference temperatures) for classifying the outdoor air temperature is one, the standard state may be the state in which the outdoor air temperature is the reference temperature corresponding to the threshold.

The correction coefficient based on the capacity ratio, indicated by Y in formula (1), will now be described. FIG. 3 is a diagram showing an example of the value of the correction coefficient based on the capacity ratio. The value of the correction coefficient based on the capacity ratio is stored in the storage device (non-volatile memory) of the control unit 6 in a table format, for example, as shown in FIG. 3, or in the correction coefficient storage unit 604 in the example shown in FIG. 1. However, the storage format is not limited to this. Each value of the correction coefficient based on the capacity ratio stored in the correction coefficient storage unit 604 is read into the memory of the control unit 6 as a parameter for correcting the judgment threshold when judging the presence or absence of a refrigerant leak.

In the example shown in FIG. 3, the value (Y) of the correction coefficient according to the capacity ratio (Ry) is set by two thresholds, a first standard capacity ratio (Ry1) and a second standard capacity ratio (Ry2). The second standard capacity ratio is larger than the first standard capacity ratio. This divides the capacity ratio into three ratio ranges: high, medium, and low. The correction coefficient when the capacity ratio is in the standard state is set smaller than the correction coefficient when the capacity ratio is in a state other than the standard state. In the example shown in FIG. 3, the standard state of the capacity ratio is when the capacity ratio is equal to or larger than the first standard capacity ratio and equal to or smaller than the second standard capacity ratio (Ry1≦Ry≦Ry2). That is, when the capacity ratio is equal to or larger than the first standard capacity ratio and equal to or smaller than the second standard capacity ratio, the correction coefficient is set smaller than both the correction coefficient when the capacity ratio is less than the first standard capacity ratio (Ry<Ry1) and the correction coefficient when the capacity ratio exceeds the second standard capacity ratio (Ry2<Ry) (the relationship is shown as "large" and "small" in FIG. 3).

Therefore, the refrigerant leakage detection unit 601 corrects the judgment threshold according to the correction coefficient by the capacity ratio so that the judgment threshold is larger when the capacity ratio is less than the first standard capacity ratio and exceeds the second standard capacity ratio than when the capacity ratio is equal to or greater than the first standard capacity ratio and equal to or less than the second standard capacity ratio. The first standard capacity ratio and the second standard capacity ratio may be set so that the standard state of the capacity ratio includes, for example, 1, that is, the capacity value of the outdoor unit 2: the capacity value of the indoor unit 4 is 1:1. The correction coefficient by the capacity ratio may be set so that the larger the capacity ratio is, the greater the range in which the capacity ratio deviates from the standard state. The number of thresholds (standard capacity ratios) for classifying the capacity ratios may be three or more, or may be one. If the number of thresholds (standard capacity ratios) for classifying the capacity ratios is one, the standard state may be the state in which the capacity ratio is the standard capacity ratio corresponding to the threshold.

The correction coefficient based on the ratio of the number of operating units, indicated by Z in formula (1), will now be described. FIG. 4 is a diagram showing an example of the value of the correction coefficient based on the ratio of the number of operating units. The value of the correction coefficient based on the ratio of the number of operating units is stored in the storage device (non-volatile memory) of the control unit 6 in a table format, for example, as shown in FIG. 4, or in the correction coefficient storage unit 604 in the example shown in FIG. 1. However, the storage format is not limited to this. Each value of the correction coefficient based on the ratio of the number of operating units stored in the correction coefficient storage unit 604 is read into the memory of the control unit 6 as a parameter for correcting the determination threshold when determining whether or not there is a refrigerant leak.

In the example shown in FIG. 4, the value (Z) of the correction coefficient based on the ratio of the number of operating units (Rz) is set by two thresholds, a first standard ratio of the number of operating units (Rz1) and a second standard ratio of the number of operating units (Rz2). The second standard ratio of the number of operating units is smaller than the first standard ratio of the number of operating units. As a result, the ratio of the number of operating units is divided into three ratio ranges: high, medium, and low. The correction coefficient when the ratio of the number of operating units is in the standard state is set smaller than the correction coefficient when the ratio of the number of operating units is in a state other than the standard state. In the example shown in FIG. 4, the standard state of the ratio of the number of operating units is when the ratio of the number of operating units is equal to or greater than the first standard ratio of the number of operating units (Rz1≦Rz). Here, the correction coefficients are set so that they increase in the following order (the relationship is shown as "small", "medium", and "large" in Figure 4): when the ratio of the number of operating units is equal to or greater than the first standard ratio of the number of operating units (Rz1≦Rz), when it is less than the first standard ratio of the number of operating units and equal to or greater than the second standard ratio of the number of operating units (Rz2≦Rz<Rz1), and when it is less than the second standard ratio of the number of operating units (Rz<Rz2).

Therefore, the refrigerant leakage detection unit 601 corrects the judgment threshold according to the correction coefficient based on the ratio of the number of operating units so that the judgment threshold increases in the following order: when the ratio of the number of operating units is equal to or greater than the first reference ratio of the number of operating units; when the ratio of the number of operating units is less than the first reference ratio of the number of operating units and is equal to or greater than the second reference ratio of the number of operating units; and when the ratio of the number of operating units is less than the second reference ratio of the number of operating units. The first reference ratio of the number of operating units and the second reference ratio of the number of operating units may be set with the standard state of the ratio of the number of operating units being 100% (a state in which all indoor units 4 are in operation). The correction coefficient based on the ratio of the number of operating units may be set so that the greater the range in which the ratio of the number of operating units deviates from the standard state. The number of thresholds (standard ratio of the number of operating units) for classifying the ratio of the number of operating units may be three or more, or may be one. If the number of thresholds (standard ratio of the number of operating units) for classifying the ratio of the number of operating units is one, the standard state may be a state in which the ratio of the number of operating units is the standard ratio of the number of operating units corresponding to the threshold.

The correction coefficient by the input unit 603 indicated by W in formula (1) will be described. The value of the correction coefficient by the input unit 603 is input by, for example, a user switching, operating, or setting a switch on the control board of the control unit 6, the operation panel of the outdoor unit 2, or the remote control of the indoor unit 4. The input correction coefficient value is stored in, for example, a storage device (non-volatile memory) of the control unit 6, or in the example shown in FIG. 1, the correction coefficient storage unit 604. When correcting the judgment threshold value when judging the presence or absence of a refrigerant leak, the refrigerant leak detection unit 601 reads the correction coefficient by the input unit 603 from the correction coefficient storage unit 604 as a parameter into the memory of the control unit 6. As a result, the correction coefficient input by the input unit 603 is applied to the refrigerant leak detection unit 601.

The correction coefficient (W) by the input unit 603 is set arbitrarily depending on, for example, the environment in which the air conditioning device 1 is installed, and is used separately from the correction coefficient based on the outside air temperature (X), the correction coefficient based on the capacity ratio (Y), and the correction coefficient based on the ratio of the number of operating units (Z), to more flexibly correct the judgment threshold.

In this embodiment, the timing at which the judgment threshold is corrected is assumed to be a predetermined timing at which the air conditioning device 1 continues to operate from the appropriate state, that is, after the parameters for calculating the predicted opening of the indoor expansion valve 404 are acquired. However, as a modified example, the correction timing of the judgment threshold may be varied according to a correction coefficient. For example, when the parameters for calculating the predicted opening of the indoor expansion valve 404 in the appropriate state are acquired, the judgment threshold is corrected according to a correction coefficient based on the capacity ratio and a correction coefficient based on the ratio of the number of operating units. Then, when determining whether or not refrigerant is leaking from the pipes (the outdoor pipes 201 and the indoor pipes 401) that form the flow path through which the refrigerant flows, the judgment threshold is corrected according to a correction coefficient based on the outside air temperature.

In this way, according to this embodiment and the modified example, it is possible to detect refrigerant leakage from the piping (the outdoor piping 201 and the indoor piping 401) based on the difference between the actual opening and the predicted opening of the indoor expansion valve 404. At that time, the judgment threshold for determining whether or not there is a refrigerant leakage can be corrected by a predetermined correction coefficient.

For example, if the outdoor air temperature deviates from the rated temperature of the air conditioning device 1 in the proper state, the accuracy of the predicted opening degree of the indoor expansion valve 404 may deteriorate depending on the degree of deviation. Even in this case, the presence or absence of refrigerant leakage can be accurately determined by correcting the judgment threshold according to the correction coefficient for the outdoor air temperature. That is, according to this embodiment, the value of the correction coefficient for the outdoor air temperature is set smaller when the outdoor air temperature is in a standard state (above the first reference temperature and below the second reference temperature) than when the outdoor air temperature is in a non-standard state. Therefore, the judgment threshold can be corrected according to the correction coefficient for the outdoor air temperature so that the judgment threshold is larger when the outdoor air temperature is in a non-standard state than when the outdoor air temperature is in a standard state. This makes it possible to improve the accuracy of refrigerant leakage detection according to the outdoor air temperature.

The judgment threshold can also be corrected using a correction coefficient based on the capacity ratio. For example, the value of the correction coefficient based on the capacity ratio is set smaller when the capacity ratio is in a standard state (greater than or equal to the first standard capacity ratio and less than or equal to the second standard capacity ratio) than when the capacity ratio is in a non-standard state. Therefore, the judgment threshold can be corrected according to the correction coefficient based on the capacity ratio so that the judgment threshold is larger when the capacity ratio is in a non-standard state than when it is in a standard state. This makes it possible to improve the accuracy of refrigerant leakage detection using the capacity ratio as well.

Furthermore, the judgment threshold can be corrected using a correction coefficient based on the ratio of the number of operating units. For example, the value of the correction coefficient based on the ratio of the number of operating units is set smaller when the ratio of the number of operating units is in a standard state (exceeding the first reference ratio of the number of operating units) than when the ratio of the number of operating units is other than the standard state. Therefore, the judgment threshold can be corrected according to the correction coefficient based on the ratio of the number of operating units so that the judgment threshold is larger when the ratio of the number of operating units is other than the standard state than when the ratio of the number of operating units is in the standard state. This makes it possible to improve the accuracy of refrigerant leakage detection based on the ratio of the number of operating units as well.

In addition, the judgment threshold can be corrected using a correction coefficient from the input unit 603. For example, the value of the correction coefficient from the input unit 603 is set arbitrarily depending on the environment in which the air conditioning device 1 is installed, and can be used separately from the correction coefficients based on the outside air temperature, the capacity ratio, and the ratio of the number of operating units. This allows the judgment threshold to be corrected more flexibly.

In this way, according to this embodiment and the modified example, it is possible to increase the degree of freedom in correcting the judgment threshold. For example, the judgment threshold can be more appropriately corrected depending on the environment in which the air conditioning device 1 is installed. As a result, it becomes possible to accurately detect refrigerant leaks even under various environments and installation conditions.

Although the embodiments of the present invention (including modifications) have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. Such novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the gist of the invention. These embodiments and modifications are included in the scope and gist of the invention, and are included in the scope of the invention and its equivalents as set forth in the claims.

1...air conditioning device, 2...outdoor unit, 4...indoor unit, 6...control unit, 201...outdoor side piping, 201a...suction pipe, 201b...discharge pipe, 202...compressor, 203...first pressure detection unit (high pressure detection unit), 204...outdoor heat exchanger, 205...outdoor blower, 206...outdoor expansion valve, 207...second pressure detection unit (low pressure detection unit), 208...outdoor temperature detection unit, 209...four-way valve, 210...gas-liquid separator (accumulator), 401...indoor side piping, 402...indoor heat exchanger, 403...indoor blower, 404...indoor expansion valve, 601...refrigerant leakage detection unit, 602...predicted opening degree storage unit, 603...input unit, 604...correction coefficient storage unit.

Claims (2)

an outdoor unit having a compressor that draws in a refrigerant, compresses it, and discharges it, an outdoor heat exchanger that exchanges heat between outdoor air and the refrigerant, an outdoor blower that draws in the outdoor air and blows the air that has been heat exchanged in the outdoor heat exchanger out to the outside, a first pressure detection unit that detects a first pressure of the refrigerant discharged from the compressor, a second pressure detection unit that detects a second pressure of the refrigerant drawn into the compressor, and an outdoor air temperature detection unit that detects an outdoor air temperature, which is the temperature of the air outside the room;
at least one indoor unit including an indoor heat exchanger that exchanges heat between indoor air and the refrigerant, an indoor blower that draws in indoor air and blows the air that has been heat exchanged by the indoor heat exchanger into the room, and an indoor expansion valve that can adjust the flow rate of the refrigerant according to its opening degree;
A control unit for controlling the operation of the outdoor unit and the indoor unit,
An air conditioning apparatus in which the outdoor unit and the indoor unit are connected by a pipe through which the refrigerant flows,
the control unit has a refrigerant leakage detection unit that acquires an actual opening, which is a current opening of the indoor expansion valve, calculates a predicted opening that is predicted as the current opening of the indoor expansion valve based at least on the rotation speed of the compressor, the first pressure and the second pressure of the refrigerant, and the opening of the indoor expansion valve on the assumption that the refrigerant is not leaking from the piping, and compares a difference between the actual opening and the predicted opening with a judgment threshold value that can be corrected from an initial value to detect leakage of the refrigerant from the piping;
the refrigerant leakage detection unit corrects the determination threshold by multiplying the initial value by a correction coefficient based on the outside air temperature so that the determination threshold is larger when the outside air temperature is less than the first reference temperature and exceeds the second reference temperature than when the outside air temperature is equal to or greater than the first reference temperature and equal to or less than a second reference temperature that is greater than the first reference temperature ;
an air conditioning apparatus which calculates a ratio between a rated capacity of the outdoor unit and a rated capacity of the indoor unit as a capacity ratio, and corrects the judgment threshold by multiplying the initial value by a correction coefficient based on the capacity ratio so that the judgment threshold is larger when the capacity ratio is less than the first standard capacity ratio or exceeds the second standard capacity ratio than when the capacity ratio is equal to or greater than a first standard capacity ratio and equal to or less than a second standard capacity ratio that is greater than the first standard capacity ratio. an outdoor unit having a compressor that draws in a refrigerant, compresses it, and discharges it, an outdoor heat exchanger that exchanges heat between outdoor air and the refrigerant, an outdoor blower that draws in the outdoor air and blows the air that has been heat exchanged in the outdoor heat exchanger out to the outside, a first pressure detection unit that detects a first pressure of the refrigerant discharged from the compressor, a second pressure detection unit that detects a second pressure of the refrigerant drawn into the compressor, and an outdoor air temperature detection unit that detects an outdoor air temperature, which is the temperature of the air outside the room;
at least one indoor unit including an indoor heat exchanger that exchanges heat between indoor air and the refrigerant, an indoor blower that draws in indoor air and blows the air that has been heat exchanged by the indoor heat exchanger into the room, and an indoor expansion valve that can adjust the flow rate of the refrigerant according to its opening degree;
A control unit for controlling the operation of the outdoor unit and the indoor unit,
An air conditioning apparatus in which the outdoor unit and the indoor unit are connected by a pipe through which the refrigerant flows,
the control unit has a refrigerant leakage detection unit that acquires an actual opening, which is a current opening of the indoor expansion valve, calculates a predicted opening that is predicted as the current opening of the indoor expansion valve based at least on the rotation speed of the compressor, the first pressure and the second pressure of the refrigerant, and the opening of the indoor expansion valve on the assumption that the refrigerant is not leaking from the piping, and compares a difference between the actual opening and the predicted opening with a judgment threshold value that can be corrected from an initial value to detect leakage of the refrigerant from the piping;
the refrigerant leakage detection unit corrects the determination threshold by multiplying the initial value by a correction coefficient based on the outside air temperature so that the determination threshold is larger when the outside air temperature is less than the first reference temperature and exceeds the second reference temperature than when the outside air temperature is equal to or greater than the first reference temperature and equal to or less than a second reference temperature that is greater than the first reference temperature ;
a ratio between a rated capacity of the outdoor unit and a rated capacity of the indoor unit is calculated as a capacity ratio, and the determination threshold is corrected by multiplying the initial value by a correction coefficient based on the capacity ratio so that the determination threshold is larger when the capacity ratio is less than the first standard capacity ratio or exceeds the second standard capacity ratio than when the capacity ratio is equal to or greater than a first standard capacity ratio and equal to or less than a second standard capacity ratio that is greater than the first standard capacity ratio;
The air conditioning apparatus varies the timing for correcting the determination threshold value using each of a plurality of correction coefficients.

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