JP2014066465A - Air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress frequent generation of protection stop of a compressor even in short pipe connection and to improve user's comfortableness.SOLUTION: An air conditioner constituting a refrigeration cycle by connecting an outdoor unit and an indoor unit by connection pipes includes: a protection control part which monitors a physical quantity concerned with the refrigeration cycle, and when the monitored physical quantity reaches a protection control determination value, starts protection control so that a compressor should not be stopped; a protection stop part which when the monitored physical quantity reaches a protection stop determination value, stops protection of the compressor; short pipe connection determination means for determining short pipe connection in which a length of a connection pipe is a set value or less; and a protection control correction part which when the short pipe connection determination means determines the short pipe connection, corrects the protection control determination value to avoid the protection stop.

Description

  The present invention relates to an air conditioner in which an outdoor unit and an indoor unit are connected by a connection pipe, and more particularly to a type in which surplus refrigerant changes depending on the length of the connection pipe to be connected.

  As background art in this technical field, there is JP-A-04-003866 (Patent Document 1). In this publication, the refrigerant amount is determined by using the suction superheat degree or the discharge superheat degree. Japanese Patent Laid-Open No. 04-151475 (Patent Document 2) is available. In this publication, the refrigerant amount is determined from the suction superheat degree and the discharge superheat degree, the indoor / outdoor temperature, and the pipe length ratio with respect to a predetermined standard length.

Japanese Patent Laid-Open No. 04-003866 Japanese Patent Laid-Open No. 04-151475

To reduce the installation work of the air conditioner, when a certain amount of refrigerant is sealed in the outdoor unit from the shipping stage, the pipe connecting the outdoor unit and the indoor unit (hereinafter referred to as connection pipe) is installed to a predetermined length. There is an air conditioner that does not need to be filled with refrigerant (hereinafter referred to as chargeless). On the other hand, when the air conditioner is installed with a short pipe connection having a short connection pipe length as a disadvantage, the cycle volume is small and surplus refrigerant is generated. Therefore, the high-pressure pressure on the compressor discharge side at the time of operation transition is likely to increase as compared to a long pipe connection with the same refrigerant filling amount and a long connection pipe length. There is protection control for the purpose of suppressing and lowering the increase of the high pressure, but if the pressure increase gradient is exceeded, the compressor may be stopped by high pressure protection. If such a compressor protection stop is repeatedly performed, the user's comfort may be impaired.
Therefore, an object of the present invention is to suppress frequent stoppage of the compressor as described above even in the case of a short pipe connection, and to improve user comfort.

In order to solve the above problems, for example, the configuration described in the claims is adopted.
The present application includes a plurality of means for solving the above-described problems. To give an example of the above, “a compressor capable of frequency control, an outdoor heat exchanger, an outdoor expansion valve whose refrigerant flow rate can be adjusted, and the outdoor An outdoor unit having an outdoor fan that blows air to the heat exchanger, an indoor heat exchanger, an indoor expansion valve with adjustable refrigerant flow rate, and an indoor fan that blows air to the indoor heat exchanger An air conditioner that configures a refrigeration cycle by connecting the outdoor unit and the indoor unit with a connection pipe, and monitoring the physical quantity related to the refrigeration cycle, and when the monitored physical quantity reaches a protection control judgment value, the compressor A protection control unit for starting protection control so as not to be stopped, a protection stop unit for stopping protection of the compressor when the monitored physical quantity reaches a protection stop judgment value, and a length of the connection pipe are set. Is less than or equal to the value When the short pipe connection determining means for determining that the pipe is connected and the short pipe connection determining means determines that the short pipe connection is established, the protection control determination is performed so as to avoid the protection stop. And a protection control correcting unit that corrects the value ”.

ADVANTAGE OF THE INVENTION According to this invention, even if it is a short piping connection, the user's comfort can be improved by suppressing the frequent stop of the protection stop of the compressor by air conditioner protection, and enabling a continuous driving | operation.

Refrigeration cycle system diagram of an air conditioner implementing the present invention Configuration example of actuator control value calculation of an air conditioner implementing the present invention The flowchart which performs the short piping connection determination in the air conditioner which implements this invention

  Hereinafter, Example 1 will be described with reference to the drawings.

In the present embodiment, an example will be described in which the threshold value of the air conditioner protection control is changed based on the short pipe connection determination during the trial operation in the cooling operation mode.
In an air conditioner having a chargeless function in which a constant amount of refrigerant is sealed in an outdoor unit from the shipping stage, as a demerit, in a short pipe connection with a short connection pipe length, the cycle volume is small and a short pipe connection state is established. Therefore, in the embodiment described below, by determining the short pipe connection state, the threshold at which the protection of the high pressure is protected is changed to a low setting, the suppression of the increase of the high pressure is severe, and the operation is stopped by the air conditioner protection. Continuous operation is possible. As a result, comfort was ensured, and it was possible to eliminate the hassle of adjusting the amount of refrigerant and setting switches during installation.

  Here, the work of filling the proper amount of refrigerant at the time of air conditioner installation is listed as the most time-consuming item at the time of installation, and it is not necessary to enclose the amount of refrigerant at the time of air conditioner installation up to a certain pipe length There is an air conditioner having a chargeless function in which a constant amount of refrigerant is sealed in an outdoor unit from the shipment stage. On the other hand, as a disadvantage, the air conditioner has a short cycle connection and a short pipe connection state in a short pipe connection with a short connection pipe length. Compared with an appropriate amount of refrigerant filled, the high pressure during operation transients is likely to rise, and protection control aimed at suppressing and lowering the increase in high pressure is not in time, resulting in shutdown due to high pressure protection. In order to impair the comfort when the operation is stopped, installation work such as switching the switch to adjust the refrigerant amount to an appropriate amount at the time of installation or changing the setting to control corresponding to the short pipe connection is required. Examples of the present invention for solving this problem will be described below.

  FIG. 1 is an example of an air conditioner configuration of the present embodiment, and shows a cycle component, a refrigerant flow direction according to an operation mode, sensors, a control unit, and a remote control switch. In FIG. 1, the outdoor unit is a compressor 1, a two-way valve 3, a 3a outdoor heat exchanger, an outdoor fan 4a, an outdoor expansion valve 5a, an accumulator 6a, a gas blocking valve 7a, and a liquid blocking valve 7b. , 20 control units. The compressor 1 is a positive displacement compressor using an inverter and the operation capacity is variable. The outdoor fan 4a is driven by a DC motor, and the air volume can be adjusted. The outdoor expansion valve 5a is a flow rate adjustment valve during heating operation, and can also be used for adjusting excess refrigerant holding amount during cooling operation. The blocking valves 7a and 7b can be opened and closed such as ball valves. The indoor unit includes a 3b indoor heat exchanger, a 4b indoor fan, and a 5b indoor expansion valve. The indoor fan 4b has a plurality of air volume taps and is determined by the remote controller air volume setting. The indoor expansion valve 5b is a flow rate adjustment valve at the time of cooling operation, and is used for adjusting the excess refrigerant holding amount at the time of heating operation. Connection pipes 8a and 8b serve as flow paths for the gas refrigerant and the liquid refrigerant that connect the outdoor unit and the indoor unit.

  Although FIG. 1 shows a connection configuration with one indoor unit, a plurality of two or more units may be used. Sensors for measurement include pressure sensor A for measuring the high-pressure side pressure, high-pressure shut-off device B used for protection when abnormal high pressure is reached, sensor C used for measuring compressor discharge refrigerant temperature, outside air temperature It consists of a sensor D used for measurement and a sensor E that measures the room temperature. A pressure / temperature sensor for measurement may be attached according to other control purposes.

  FIG. 2 shows a configuration example of the actuator control value calculation performed in the controller 20 of the air conditioner of the present embodiment. For each actuator, the control amount is adjusted by the control unit according to the measured value of the pressure / temperature sensor indicated in the control value calculation parameter, the temperature / air volume setting of the remote control switch 21 and the operating temperature condition, and the refrigeration cycle is adjusted. Perform operation control.

  The flow of the refrigerant at the time of the trial operation in which the short pipe connection determination is performed in the cooling operation mode will be described with reference to FIG. The direction of refrigerant flow in the cooling operation is indicated by solid arrows. The high-pressure and high-temperature gas refrigerant discharged from the compressor 1 passes through the four-way valve 2 and flows into the outdoor heat exchanger 3a. Heat is radiated to the air through the outdoor heat exchanger 3a by the amount of air blown by the outdoor fan 4a, and the high-pressure and high-temperature gas refrigerant is condensed to become a high-pressure liquid refrigerant. The high-pressure liquid refrigerant exiting the outdoor heat exchanger 3a passes through the outdoor expansion valve 5a, the liquid blocking valve 6b, and the connection liquid pipe 7b, and flows into the indoor unit. The high-pressure liquid refrigerant that has flowed into the indoor unit is decompressed by the indoor expansion valve 5b, becomes low-pressure low-temperature liquid refrigerant, and flows into the indoor heat exchanger 3b. The indoor fan 4b absorbs heat from the air through the indoor heat exchanger 3b by the amount of air blown from the indoor fan 4b, and the low-pressure and low-temperature liquid refrigerant evaporates into a low-pressure gas refrigerant. The low-pressure gas refrigerant exiting the indoor heat exchanger 3b flows into the outdoor unit from the connecting gas pipe 8a, passes through the gas blocking valve 6a and the four-way valve 2, and is separated from the liquid refrigerant mixed with the gas refrigerant by the accumulator, Only the gas refrigerant is sucked into the compressor 1, compressed again, and discharged from the compressor 1 as a high-pressure and high-temperature gas refrigerant. In this refrigeration cycle, the cooling operation is performed by the air that has passed through the heat exchanger blown out from the indoor unit as cold air by the action of absorbing heat from the air in the indoor heat exchanger.

  Next, a method for determining the short pipe connection from the actuator control value when the cooling operation is stable will be described with reference to FIG. Since each actuator has a target to be controlled such as various temperatures and pressures, it is necessary to change the actuator to be selected for determination according to the control specifications when determining the short pipe connection from the behavior of the actuator peculiar to the short pipe connection. As an example, the control specifications in FIG. 2 are such that the target frequency is uniquely determined regardless of the cycle state of the compressor, the outdoor expansion valve is fixed at the fully open position, and the indoor expansion valve is the refrigerant discharged from the compressor. It is assumed that the degree of superheat is calculated to an opening that sets a predetermined target value, and the outdoor fan performs cooling operation by providing a target value for high pressure and controlling the air volume.

  In this control specification, when all-room operation is performed and the cooling operation is performed with the maximum indoor set air volume, the change tendency of the actuator control value that is manifested by the short pipe connection appears in the outdoor fan air volume and the indoor expansion valve opening. Excess refrigerant generated by the short pipe connection needs to be stored in the outdoor heat exchanger or accumulator that becomes the condenser. Considering the case of storing in the outdoor heat exchanger, if there is no difference in the control value of the compressor frequency, the indoor expansion The amount of refrigerant circulation is suppressed by reducing the opening of the valve. Further, if the liquid refrigerant accumulates in the outdoor heat exchanger, which is a condenser, the high-pressure pressure tends to increase, so the outdoor fan air volume increases to keep the target high-pressure. From the above, during cooling operation, the criterion for short pipe connection is that the outdoor fan air volume is large and the indoor unit expansion valve opening is small.

  Therefore, by storing the actuator control value at the time of proper refrigerant filling under various operating conditions in the control unit as a data table, in the data table that matches the operating conditions (temperature conditions and remote control setting conditions) at the time of trial operation By comparing with the actuator control value, it is determined whether or not it is a short pipe connection.

  The flow for performing the short pipe connection determination will be described based on the flowchart of FIG. First, the timing of determination is during trial operation, and then the operation mode is grasped (cooling operation in this embodiment). Next, the stability of the cooling operation is determined from the stability of the control value of the actuator, and the short pipe connection determination is performed. If it is determined that the connection is a short pipe connection, it is stored in the control unit 20 and the threshold value for protection control is changed.

  More specifically, the air conditioner of the present embodiment includes a protection stop unit that stops protection of the compressor 1 when the monitored physical quantity reaches the protection stop determination value. An example of the protection stop unit is the high-pressure shut-off device B in FIG. 1, and the high-pressure shut-off device B stops the compressor 1 when the refrigerant pressure on the discharge side of the compressor 1 reaches a predetermined protection stop judgment value. .

  Further, the control unit 20 monitors a physical quantity related to the refrigeration cycle, and when the monitored physical quantity reaches the protection control determination value, the protection control unit 22 (not shown) starts protection control so that the compressor does not stop. ). That is, if the above-described protection stop of the compressor 1 frequently occurs, the user's comfort may be impaired. Therefore, if the monitored physical quantity reaches the protection control determination value before reaching the protection stop determination value, the compressor should be stopped. Protection control is started so as not to become.

  For example, when the monitored physical quantity is the refrigerant pressure on the discharge side of the compressor 1, the protection stop determination value is larger than the protection control determination value, and when the protection control is started, the refrigerant on the discharge side of the compressor 1 is started. The protection control unit 22 controls the frequency of the compressor 1 to be lowered so that the pressure is gradually shifted from an upward trend to a downward trend so that the compressor is not in a state to be stopped.

  However, even if the frequent stoppage of protection is suppressed in this way, if the short pipe connection is used, the assumed pressure rise gradient may be exceeded, and the compressor is protected by stopping the protection of the compressor. There is a possibility of stopping, and there is a possibility that the protection of the compressor is repeatedly stopped.

  Therefore, the control unit 20 according to the present embodiment includes a short pipe connection determination unit 23 (not shown) that determines that the length of the connection pipe is a short pipe connection that is equal to or less than a set value, and a short pipe connection determination unit. 23, a protection control correcting unit 24 (not shown) that corrects the protection control judgment value so as to avoid the protection stop when it is determined that the short pipe connection is established.

  For example, when the monitored physical quantity is the refrigerant pressure on the discharge side of the compressor 1, the discharge-side refrigerant pressure tends to increase when the short pipe is connected. There is a possibility that the protection of 1 is frequently stopped. Therefore, in the present embodiment, the short pipe connection determining means 23 and the protection control correcting section 24 are provided, so that when the short pipe connection determining means 23 determines that the short pipe is connected, the protection control correcting section 24 performs the protection control. It is modified so as to avoid the protection stop by changing the judgment value to be lowered.

  When monitoring the refrigerant temperature on the discharge side of the compressor 1 as a monitored physical quantity, the protection control unit 22 puts the compressor 1 in a state to be stopped when the discharge side refrigerant temperature reaches the protection control determination value. Protection control is started so as not to occur, but when the short pipe connection determining means 23 determines that the short pipe is connected, the protection control correcting unit 24 determines the protection control determination value (set value of the discharge side refrigerant temperature). It is modified so as to avoid the protection stop by changing to lower.

  The refrigerant pressure on the discharge side of the compressor 1 described above may be provided with a pressure sensor on the discharge side, or by providing a temperature sensor for detecting the liquid pipe temperature of the condenser, from the detected value of the temperature sensor. The compressor discharge side pressure may be estimated and used.

  As described above, since the refrigerant pressure on the discharge side of the compressor 1 can be estimated from the liquid pipe temperature of the condenser, the “liquid refrigerant on the discharge side” is used by using the liquid pipe temperature of the condenser as a judgment value instead of the refrigerant pressure on the discharge side. “Pressure” may be read and read as “condenser liquid tube temperature”. That is, as the monitored physical quantity, the liquid pipe temperature of the heat exchanger acting as a condenser of the indoor heat exchanger or the outdoor heat exchanger may be monitored, and the protection stop judgment value is larger than the protection control judgment value. It becomes. In this case, the condenser liquid pipe temperature corresponding to the case where the discharge side refrigerant pressure reaches the protection control judgment value is stored as the protection control judgment value, and the discharge side refrigerant pressure reaches the protection stop judgment value. The condenser liquid tube temperature corresponding to the case is stored as a protection stop judgment value. Accordingly, the protection control unit 22, the protection stop unit, and the protection control correction unit can be controlled similarly to the case of the refrigerant pressure on the discharge side.

  Moreover, the refrigerant pressure on the suction side of the compressor 1 can be monitored as a monitored physical quantity, and the control in the short pipe connection can be performed. In this case, a pressure sensor may be provided on the suction side of the compressor 1, or a temperature sensor for detecting the liquid pipe temperature of the evaporator after decompression is provided, and the compressor suction side pressure is determined from the detected value of the temperature sensor. May be estimated and used.

  When monitoring the refrigerant pressure on the suction side of the compressor 1 as a monitored physical quantity, the compressor 1 does not enter a state to be stopped when the refrigerant pressure on the suction side reaches the protection control judgment value by the protection control unit 22. However, when the short pipe connection determination means 23 determines that the short pipe is connected, the protection control correction unit 24 sets the protection control determination value (the set value of the suction side refrigerant pressure). It is modified so that the protection stop is avoided by changing to raise.

  The refrigerant pressure on the suction side of the compressor 1 described above may be provided with a pressure sensor on the suction side, or provided with a temperature sensor that detects the evaporator liquid pipe temperature after decompression, thereby detecting the temperature sensor. The compressor discharge side pressure may be estimated from the value and used.

  As described above, since the refrigerant pressure on the suction side of the compressor 1 can be estimated from the evaporator liquid pipe temperature after decompression, the evaporator liquid pipe temperature after decompression is used as a judgment value instead of the refrigerant pressure on the suction side. The “refrigerant pressure on the suction side” may be read as “evaporator liquid pipe temperature after decompression” for control. That is, as the monitored physical quantity, the liquid pipe temperature of the heat exchanger acting as an evaporator of the indoor heat exchanger or the outdoor heat exchanger may be monitored, and the protection stop judgment value is smaller than the protection control judgment value. It becomes. In this case, the liquid pipe temperature of the evaporator corresponding to the case where the suction side refrigerant pressure reaches the protection control judgment value is stored as the protection control judgment value, and the suction side refrigerant pressure reaches the protection stop judgment value. The liquid pipe temperature of the evaporator corresponding to the case is stored as a protection stop judgment value. Accordingly, the protection control unit 22, the protection stop unit, and the protection control correction unit can be controlled similarly to the case of the refrigerant pressure on the discharge side.

  When monitoring the pressure ratio defined by the ratio of the compressor discharge side pressure divided by the suction side pressure as the monitored physical quantity, the protection control unit 22 compresses the compression ratio when the pressure ratio reaches the protection control judgment value. The protection control is started so that the machine 1 does not stop. However, when the short pipe connection determining means 23 determines that the short pipe is connected, the protection control correcting unit 24 sets the protection control judgment value ( Correction is made so as to avoid the protection stop by changing to lower the pressure ratio set value defined by the ratio of the compressor discharge side pressure divided by the suction side pressure.

  The pressure ratio defined by the ratio obtained by dividing the compressor discharge side pressure by the suction side pressure has a temperature sensor that detects the condenser liquid pipe temperature and the evaporator liquid pipe temperature after depressurization. Originally, the compressor discharge side pressure and the suction side pressure may be estimated and used.

  It is desirable that the short pipe connection determination described above is performed in a test operation performed after the air conditioner is installed.

  When the short pipe connection is determined as described above, and it is determined that the short pipe is connected, the protection control correction unit 24 corrects the protection stop so as to avoid frequent protection stop. It is possible to improve user comfort in the case of pipe connection.

  In addition, when performing the cooling operation as described above, the short pipe connection determination unit 23 determines that the short pipe connection is established when a set time elapses when the air volume of the outdoor fan 4a is equal to or greater than the set air volume. Good. Alternatively, it may be determined as a short connection pipe when a set time has elapsed when the opening of the indoor expansion valve 5b is equal to or less than the set opening, or an AND condition with the outdoor fan 4a may be used. Further, in the case where the compressor control of the above control specification is a control in which the target frequency is calculated from the cycle state (compressor discharge refrigerant pressure, outlet refrigerant temperature, etc.) and the frequency is varied, the frequency of the compressor 1 is used as a criterion. A case where the set time elapses in a state where the frequency becomes equal to or lower than the set frequency may be added.

  In this case, the determination value of the short piping connection of the actuator (outdoor fan 4a, indoor expansion valve 5b, compressor 4) stored in the storage device varies depending on the outside air temperature, the room air temperature, the remote control set temperature, and the remote control set air volume. Therefore, it is preferable to change and set them for each condition combined in the use range of the air conditioner.

  In this embodiment, an example will be described in which the threshold value of the air conditioner protection control is changed based on the short pipe connection determination during the trial operation in the heating operation mode. The example of the air conditioner configuration of the present embodiment and the configuration example of the actuator control value calculation performed in the control unit 20 are as described above with reference to FIGS. 1 and 2.

  The flow of the refrigerant at the time of the trial operation for performing the short pipe connection determination in the heating operation mode will be described with reference to FIG. The flow direction of the refrigerant in the heating operation is indicated by a dashed arrow. The high-pressure and high-temperature gas refrigerant discharged from the compressor 1 passes through the four-way valve 2, the gas blocking valve 6a, and the connection gas pipe 8a, and flows into the indoor heat exchanger 3b of the indoor unit. The high-pressure and high-temperature gas refrigerant that has flowed into the indoor heat exchanger 3b radiates heat to the air via the indoor heat exchanger 3a by the amount of air blown by the indoor fan 4b, and the high-pressure and high-temperature gas refrigerant condenses into high-pressure liquid refrigerant. The high-pressure liquid refrigerant exiting the indoor heat exchanger 3b passes through the indoor expansion valve 5b, the connecting liquid pipe 7b, and the liquid blocking valve 6b, and flows into the outdoor unit. The high-pressure liquid refrigerant that has flowed into the outdoor unit is decompressed by the outdoor expansion valve 5a, becomes low-pressure low-temperature liquid refrigerant, and flows into the outdoor heat exchanger 3a. The outdoor fan 4a absorbs heat from the air via the outdoor heat exchanger 3a, and the low-pressure and low-temperature liquid refrigerant evaporates into a low-pressure gas refrigerant. The low-pressure gas refrigerant that has exited the outdoor heat exchanger 3a passes through the four-way valve 2, the liquid refrigerant mixed with the gas refrigerant is separated by the accumulator, and only the gas refrigerant is sucked into the compressor 1 and compressed again to be high-pressure and high-temperature. The gas refrigerant is discharged from the compressor 1. In this refrigeration cycle, the heating operation is performed by the air that has passed through the heat exchanger blown out from the indoor unit as warm air by the action of radiating heat to the air in the indoor heat exchanger.

  Next, a method for determining the short pipe connection from the actuator control value when the heating operation is stable will be described with reference to FIG. Since each actuator has a target to be controlled such as various temperatures and pressures, it is necessary to change the actuator to be selected for determination according to the control specifications when determining the short pipe connection from the behavior of the actuator peculiar to the short pipe connection. As an example, the control specification of FIG. 2 adjusts the frequency so that the compressor becomes the target high pressure (discharge side refrigerant pressure), and the indoor expansion valve sets the superheat degree of the refrigerant discharged from the compressor to a constant target value. The heating operation is controlled by adjusting the opening degree to be adjusted, the indoor expansion valve is fixed at the opening degree, and the outdoor fan has an air volume corresponding to the outside air temperature.

  When heating operation is performed with all-room operation and the maximum indoor set air volume in this control specification, the change tendency of the actuator control value that appears due to the short pipe connection appears in the compressor frequency and the outdoor expansion valve opening. The surplus refrigerant generated by the short pipe connection must be stored in the indoor heat exchanger or accumulator as a condenser. Considering the case of storing in the indoor heat exchanger, the amount of refrigerant circulation can be reduced by reducing the opening of the outdoor expansion valve. If the liquid refrigerant accumulates in the indoor heat exchanger, which is a condenser, the high-pressure pressure tends to increase, so the compressor frequency remains at the target high-pressure and becomes small. From the above, it is a criterion for short pipe connection that both the compressor frequency and the outdoor unit expansion valve opening are small.

  Therefore, by storing the data table in the control unit, whether it is a short pipe connection by comparing with the actuator control value in the data table that matches the operating condition (temperature condition and remote control setting condition) at the time of trial operation Can be determined.

  The flow for performing the short pipe connection determination will be described based on the flowchart of FIG. First, the determination timing is a trial operation, and the operation mode is grasped (heating operation in this embodiment). Next, it is determined whether the heating operation is stable. For example, the short pipe connection determination is performed after it is determined that the heating operation is stable by reaching within a predetermined range from a target such as high pressure or superheat. If it is determined that the connection is a short pipe connection, it is stored in the control unit 20 and the threshold value for protection control is changed.

  That is, when performing the heating operation, the short pipe connection determining unit 23 determines that the short pipe connection is established when a set time has elapsed when the opening of the outdoor expansion valve 5a is equal to or less than the set opening. Good. Alternatively, it may be determined that the short pipe connection is established when the set time has elapsed when the frequency of the compressor 1 is equal to or lower than the set frequency, and these conditions may be AND conditions.

In this case, the determination value of the short piping connection of the actuator (outdoor fan 4a, indoor expansion valve 5b, compressor 4) stored in the storage device varies depending on the outside air temperature, the room air temperature, the remote control set temperature, and the remote control set air volume. Therefore, it is preferable to change and set them for each condition combined in the use range of the air conditioner.

DESCRIPTION OF SYMBOLS 1 ... Compressor, 2 ... Four way valve, 3a, 3b ... Heat exchanger, 5a, 5b ... Expansion valve, 6 ... Accumulator, 7a, 7b ... Stop valve, 8a, 8b ... Connection piping, 20 ... Control part, 21 ... Remote control switch, 22 ... protection control unit, 23 ... short pipe connection determination means, 24 protection control correction unit.

Claims (5)

An outdoor unit having a frequency-controllable compressor, an outdoor heat exchanger, an outdoor expansion valve with adjustable refrigerant flow rate, and an outdoor fan that blows air to the outdoor heat exchanger,
An indoor unit having an indoor heat exchanger, an indoor expansion valve with adjustable refrigerant flow rate, and an indoor fan that blows air to the indoor heat exchanger,
In the air conditioner that configures the refrigeration cycle by connecting the outdoor unit and the indoor unit with a connection pipe,
A protection control unit that monitors a physical quantity related to the refrigeration cycle, and starts protection control so that the compressor does not stop when the monitored physical quantity reaches a protection control determination value;
A protection stop unit for stopping protection of the compressor when the monitored physical quantity reaches a protection stop judgment value;
A short pipe connection determination means for determining that the length of the connection pipe is a short pipe connection which is equal to or less than a set value;
A protection control correction unit that corrects the protection control determination value so as to avoid the protection stop when the short pipe connection determination unit determines that the short pipe connection is established; Air conditioner to do. In the air conditioner according to claim 1,
When performing cooling operation, the short pipe connection determining means is
When the set time has passed when the outdoor fan air flow is equal to or higher than the set air flow, when the open time of the indoor expansion valve is lower than the set open time, or when the compressor frequency is set An air conditioner that determines that the end pipe connection is established when a set time elapses in a state that is equal to or lower than a frequency. In the air conditioner according to claim 1,
When performing the heating operation, the short pipe connection determining means is
The short pipe connection is established when a set time has elapsed when the opening of the outdoor expansion valve is less than or equal to a set opening, or when a set time has elapsed when the frequency of the compressor is below the set frequency. It is determined that the air conditioner is. In the air conditioner in any one of Claims 1-3,
The monitored physical quantity is a refrigerant pressure on the discharge side of the compressor or a liquid pipe temperature of a heat exchanger acting as a condenser of the indoor heat exchanger or the outdoor heat exchanger, and the protection stop An air conditioner characterized in that the judgment value is larger than the protection control judgment value. In the air conditioner in any one of Claims 1-3,
The monitored physical quantity is a refrigerant pressure on the suction side of the compressor, or a liquid pipe temperature of a heat exchanger acting as a condenser of the indoor heat exchanger or the outdoor heat exchanger, and the protection stop The judgment value is a value smaller than the protection control judgment value.