JP6493160B2 - Air conditioner - Google Patents

Description

  The present invention relates to an air conditioner capable of performing a pump-down operation.

  When refrigerant leakage occurs in the indoor unit of the air conditioner, or when the air conditioner is moved or repaired, a pump-down operation for collecting the refrigerant is performed. As an air conditioner capable of performing a pump-down operation, there is a refrigerating and air-conditioning apparatus disclosed in Japanese Patent Laid-Open No. 2013-122364 (Patent Document 1).

  In the conventional refrigerating and air-conditioning apparatus disclosed in Patent Document 1, the pressure branching side opening / closing valve branches off from the liquid line between the outdoor heat exchanger and the liquid line side opening / closing valve and is connected to the suction side of the accumulator. Is provided with a pressure equalizing circuit. At the start of the pump down operation, if the high pressure detected by the high pressure detector is equal to or higher than a preset pressure, the compressor is stopped and the indoor heat exchange is fully opened prior to the pump down operation. In addition, the pressure equalization recovery operation is performed in which the pressure equalization side on / off valve provided in the pressure equalization circuit is opened while the liquid line side on / off valve is open, and the high pressure liquid line is communicated with the low pressure gas line.

  In this way, the high-density and high-pressure liquid refrigerant in the liquid line is collected in the accumulator through the pressure equalization circuit. After that, when the high pressure becomes lower than the set pressure, the pump shifts to a down operation, the liquid line side on / off valve is closed, the expansion valve is fully opened, and the pressure equalizing side on / off valve remains open to start the compressor. To do. Thus, the refrigerant on the indoor unit side is recovered to the outdoor unit side through the gas line.

  However, the conventional refrigeration and air conditioning apparatus disclosed in Patent Document 1 has the following problems.

  That is, when the pump-down operation is performed as described above, air may be mixed into the gas line side for some reason such as a crack in the pipe or an error in the procedure. In that case, if the pump-down operation is continued, a large amount of air is sucked, and the compressor operation is continued to increase the temperature inside the compressor. And if it becomes more than the ignition temperature of the lubricating oil in a compressor, it may lead to what is called a diesel explosion which a compressor bursts.

JP 2013-122364 A

  Then, the subject of this invention is providing the air conditioner which can prevent the damage of the compressor by the air mixing at the time of pump down operation.

In order to solve the above problems, the air conditioner of the present invention is
A refrigerant circuit in which a compressor, a four-way switching valve, an outdoor heat exchanger, a pressure reducing mechanism, a liquid side closing valve, an indoor heat exchanger, and a gas side closing valve are connected in this order by a refrigerant pipe;
An indoor heat exchanger temperature sensor that is installed in the indoor heat exchanger and detects the temperature of the indoor heat exchanger;
An indoor temperature sensor disposed in the indoor unit for detecting the indoor temperature;
A pump-down operation control unit that controls at least the compressor and the four-way switching valve in the refrigerant circuit to perform a pump-down operation;
During the pump-down operation by the pump-down operation control unit, a value of a difference between the indoor temperature detected by the indoor temperature sensor and the indoor heat exchanger temperature detected by the indoor heat exchanger temperature sensor is set in advance. And an operating frequency limiter that limits the upper limit value of the operating frequency of the compressor when the temperature falls below the set temperature.

  According to the above configuration, when the value of the difference between the indoor temperature and the indoor heat exchanger temperature falls below a preset temperature during the pump-down operation by the operating frequency limiting unit, that is, the indoor When the heat exchanger does not perform heat exchange and the pump-down operation is substantially finished, the upper limit value of the operation frequency of the compressor is limited.

  Therefore, even when the pump-down operation is continued even after the pump-down operation is substantially finished, even if the suction amount of the compressor is reduced and air is mixed in the refrigerant, An increase in the internal temperature of the compressor can be suppressed. That is, according to the present invention, it is possible to prevent the compressor from being damaged due to air mixing during the pump-down operation.

In the air conditioner of one embodiment,
The operating frequency limiter is
When the state where the difference between the indoor temperature and the indoor heat exchanger temperature is lower than the set temperature continues for a preset time or more, it is determined that the pump-down operation has ended, and the compression The upper limit of the machine operating frequency is limited.

  According to this embodiment, when the difference between the indoor temperature and the indoor heat exchanger temperature is lower than the set temperature, that is, when the indoor heat exchanger is not performing heat exchange for a set time or longer. Then, it is determined that the pump-down operation has substantially ended. Therefore, it is possible to reliably and correctly determine that the pump-down operation has substantially ended, and it is possible to improve reliability.

In the air conditioner of one embodiment,
The operating frequency limiter is
After limiting the upper limit value of the operating frequency of the compressor, even if the difference value between the indoor temperature and the indoor heat exchanger temperature is equal to or higher than the set temperature, the upper limit value of the operating frequency of the compressor The above-mentioned restrictions are continued.

  According to this embodiment, after the upper limit value of the operating frequency of the compressor is limited, even if the difference value between the indoor temperature and the indoor heat exchanger temperature is equal to or higher than the set temperature, the compressor The above restriction on the upper limit value of the operating frequency is continued. Therefore, even if the refrigerant that has been temporarily recovered returns to the indoor heat exchange for some reason, or any of the temperature sensors fails, the suction amount of the compressor is reduced to reduce the internal temperature. The rise can be suppressed and the reliability can be further improved.

Moreover, the air conditioner of this invention is
A refrigerant circuit in which a compressor, a four-way switching valve, an outdoor heat exchanger, a pressure reducing mechanism, a liquid side closing valve, an indoor heat exchanger, and a gas side closing valve are connected in this order by a refrigerant pipe;
An outdoor heat exchanger temperature sensor that is installed in the outdoor heat exchanger and detects the temperature of the outdoor heat exchanger;
An outdoor temperature sensor that is disposed in the outdoor unit and detects an outdoor temperature;
A pump-down operation control unit that controls at least the compressor and the four-way switching valve in the refrigerant circuit to perform a pump-down operation;
During the pump-down operation by the pump-down operation control unit, a value of a difference between the outdoor temperature detected by the outdoor temperature sensor and the outdoor heat exchanger temperature detected by the outdoor heat exchanger temperature sensor is set in advance. And an operating frequency limiter that limits the upper limit value of the operating frequency of the compressor when the temperature falls below the set temperature.

  According to the above configuration, when the value of the difference between the outdoor temperature and the outdoor heat exchanger temperature falls below a preset set temperature during the pump-down operation by the operating frequency limiting unit, that is, the outdoor When the heat exchanger does not perform heat exchange and the pump-down operation is substantially finished, the upper limit value of the operation frequency of the compressor is limited.

  Therefore, even when the pump-down operation is continued even after the pump-down operation is substantially finished, even if the suction amount of the compressor is reduced and air is mixed in the refrigerant, An increase in the internal temperature of the compressor can be suppressed. That is, according to the present invention, it is possible to prevent the compressor from being damaged due to air mixing during the pump-down operation.

In the air conditioner of one embodiment,
The operating frequency limiter is
When the state where the difference between the outdoor temperature and the outdoor heat exchanger temperature is lower than the set temperature continues for a preset time or more, it is determined that the pump-down operation has ended, and the compression The upper limit of the machine operating frequency is limited.

  According to this embodiment, when the value of the difference between the outdoor temperature and the outdoor heat exchanger temperature is lower than the set temperature, that is, when the outdoor heat exchanger is not performing heat exchange for a set time or longer. Then, it is determined that the pump-down operation has substantially ended. Therefore, it is possible to reliably and correctly determine that the pump-down operation has substantially ended, and it is possible to improve reliability.

In the air conditioner of one embodiment,
The operating frequency limiter is
After the upper limit value of the operating frequency of the compressor is limited, even if the difference between the outdoor temperature and the outdoor heat exchanger temperature is equal to or higher than the set temperature, the upper limit value of the operating frequency of the compressor The above-mentioned restrictions are continued.

  According to this embodiment, after limiting the upper limit value of the operating frequency of the compressor, even if the difference value between the outdoor temperature and the outdoor heat exchanger temperature is equal to or higher than the set temperature, the compressor The above restriction on the upper limit value of the operating frequency is continued. Therefore, even if the refrigerant that has been temporarily recovered returns to the indoor heat exchange for some reason, or any of the temperature sensors fails, the suction amount of the compressor is reduced to reduce the internal temperature. The rise can be suppressed and the reliability can be further improved.

In the air conditioner of one embodiment,
The operating frequency limiter is
The upper limit value of the operating frequency of the compressor is limited after the time since the pump-down operation started by the pump-down operation control unit has exceeded a preset time.

  According to this embodiment, the upper limit value of the operating frequency of the compressor is limited after the time from the start of the pump-down operation has elapsed for a set time or longer. Therefore, it is possible to accurately determine that the cooling cycle during the pump-down operation is stable, and to reliably and correctly determine that the pump-down operation has substantially ended.

In the air conditioner of one embodiment,
The pump down operation control unit is
When the elapsed time from the start of operation of the compressor reaches the forced stop time, the pump-down operation is terminated.

  According to this embodiment, when the elapsed time reaches the forced stop time, the pump-down operation is terminated. Therefore, even if the pump-down operation is continued even after the pump-down operation is substantially terminated. The pump down operation can be forcibly terminated.

Moreover, the air conditioner of this invention is
A refrigerant circuit in which a compressor, a four-way switching valve, an outdoor heat exchanger, a pressure reducing mechanism, a liquid side closing valve, an indoor heat exchanger, and a gas side chain valve are connected in this order by a refrigerant pipe;
A pressure sensor for detecting the suction pressure of the compressor;
A pump-down operation control unit that controls at least the compressor and the four-way switching valve in the refrigerant circuit to perform a pump-down operation;
When it is determined that the pump down operation completion condition is satisfied based on the suction pressure detected by the pressure sensor during the pump down operation by the pump down operation control unit, the upper limit value of the operation frequency of the compressor And an operating frequency limiting unit for limiting the operation.

  According to the above configuration, when the operation frequency limiting unit determines that the pump down operation completion condition is satisfied based on the suction pressure detected by the pressure sensor, that is, the pump down operation is substantially ended. If there is, a limit is imposed on the upper limit value of the operating frequency of the compressor.

  Therefore, even when the pump-down operation is continued even after the pump-down operation is substantially finished, even if the suction amount of the compressor is reduced and air is mixed in the refrigerant, the compression is performed. The rise in the internal temperature of the machine can be suppressed. That is, according to the present invention, it is possible to prevent the compressor from being damaged due to air mixing during the pump-down operation.

In the air conditioner of one embodiment,
The operating frequency limiting unit determines that the condition for completing the pump-down operation is satisfied when the state in which the suction pressure detected by the pressure sensor is equal to or lower than the atmospheric pressure continues for a preset time.

  According to this embodiment, the state in which the suction pressure detected by the pressure sensor has become equal to or lower than the atmospheric pressure, that is, the state in which the refrigerant suction amount of the compressor has decreased continues for a preset time or more. Then, it is determined that the pump-down operation has substantially ended. Accordingly, it is possible to reliably and correctly determine that the pump-down operation has substantially ended, and to improve reliability.

In the air conditioner of one embodiment,
An indoor heat exchanger temperature sensor that is installed in the indoor heat exchanger and detects the temperature of the indoor heat exchanger;
The operating frequency limiter is a preset value in which a difference value between the indoor heat exchanger temperature detected by the indoor heat exchanger temperature sensor and the saturation temperature corresponding to the suction pressure detected by the pressure sensor is set in advance. When the above state continues for a preset time or more, it is determined that the conditions for completing the pump-down operation are satisfied.

  According to this embodiment, the set value in which the value of the difference between the indoor heat exchanger temperature detected by the indoor heat exchanger temperature sensor and the saturation temperature corresponding to the suction pressure detected by the pressure sensor is set in advance. When the above state, that is, the state in which the refrigerant suction amount of the compressor is reduced, continues for a preset time or more, it is determined that the pump-down operation has substantially ended. Accordingly, it is possible to reliably and correctly determine that the pump-down operation has substantially ended, and to improve reliability.

In the air conditioner of one embodiment,
When the state where the absolute value of the slope of the time change of the suction pressure detected by the pressure sensor has become equal to or less than a preset value is continued for a preset time or more, It is determined that the conditions for completing the pump-down operation are satisfied.

  According to this embodiment, there is a state where the absolute value of the slope of the time variation of the suction pressure detected by the pressure sensor is equal to or smaller than a preset value, that is, a state where the suction amount of the compressor is reduced. The pump down operation is determined to have substantially ended when the preset time continues for a preset time. Accordingly, it is possible to reliably and correctly determine that the pump-down operation has substantially ended, and to improve reliability.

  As apparent from the above, in the air conditioner of the first invention, the value of the difference between the indoor temperature and the indoor heat exchanger temperature is set in advance by the operating frequency limiter during the pump down operation. When the temperature is lower than the set temperature, that is, when the indoor heat exchanger is not performing heat exchange and the pump-down operation is substantially finished, the upper limit value of the operating frequency of the compressor is limited. Is added.

  In the air conditioner of the second invention, the value of the difference between the outdoor temperature and the outdoor heat exchanger temperature is set to a preset temperature during the pump-down operation by the operating frequency limiting unit. If it is lower, that is, if the outdoor heat exchanger is not exchanging heat and the pump-down operation is substantially finished, the upper limit value of the operating frequency of the compressor is limited. Yes.

  In the air conditioner according to the third aspect of the present invention, the operating frequency limiter determines that the pump down operation completion condition is satisfied based on the suction pressure detected by the pressure sensor during the pump down operation. In this case, the upper limit value of the operating frequency of the compressor is limited.

  Therefore, in the first to third aspects of the invention, when the pump-down operation is continued even after the pump-down operation is substantially finished, the suction amount of the compressor is reduced and air is contained in the refrigerant. Even if it is a case where is mixed, the raise of the internal temperature of the said compressor can be suppressed.

  That is, according to the above-described invention, it is possible to prevent damage to the compressor due to air mixing during the pump-down operation.

It is a refrigerant circuit figure in the air conditioner of 1st Embodiment of this invention. It is a figure which shows the peripheral device connected to the control apparatus of the said 1st Embodiment. It is a flowchart of the operation frequency restriction | limiting process operation | movement of the compressor of the said 1st Embodiment. It is a figure which shows the peripheral device connected to the control apparatus in 2nd Embodiment of this invention. It is a flowchart of the operation frequency restriction | limiting process operation | movement of the compressor of the said 2nd Embodiment. It is a figure which shows the peripheral device connected to the control apparatus in 3rd Embodiment of this invention. It is a flowchart of the operation frequency restriction | limiting process operation | movement of the compressor of the said 3rd Embodiment. It is a figure which shows the peripheral device connected to the control apparatus in 4th Embodiment of this invention. It is a flowchart of the operation frequency restriction | limiting process operation | movement of the compressor of the said 4th Embodiment.

  Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.

[First Embodiment]
FIG. 1 is a refrigerant circuit diagram of the air conditioner according to the first embodiment of the present invention.

  As shown in FIG. 1, the air conditioner 1 is configured by connecting an indoor unit 2 installed indoors and an outdoor unit 3 installed outdoor by connecting pipes L1 and L2. The air conditioner 1 is a pair-type air conditioner in which the indoor unit 2 and the outdoor unit 3 are one-to-one. The indoor unit 2 is equipped with an indoor heat exchanger 4 and an indoor fan 5. The outdoor unit 3 includes a compressor 6, a four-way switching valve 7, an outdoor heat exchanger 8, an outdoor fan 9, an electric expansion valve (hereinafter simply referred to as an expansion valve) 10 as an example of the pressure reducing mechanism, and an accumulator. 11 is mounted. Further, the outdoor unit 3 is provided with a liquid side closing valve 12 and a gas side closing valve 13.

  The compressor 6, the four-way switching valve 7, the outdoor heat exchanger 8, the expansion valve 10, the indoor heat exchanger 4, the four-way switching valve 7, the accumulator 11, and the compressor 6 Are connected in this order by the refrigerant pipes and the communication pipes L1 and L2 to constitute a refrigerant circuit. Further, a liquid side closing valve 12 is interposed between the expansion valve 10 and the connecting pipe L1, while a gas side closing valve 13 is interposed between the four-way switching valve 7 and the connecting pipe L2. Yes.

  In the refrigerant circuit, an outdoor heat exchanger 8 is connected to the discharge port of the compressor 6 via a four-way switching valve 7, while the indoor heat exchanger 4 is connected via a four-way switching valve 7 and an accumulator 11. The suction port of the compressor 6 is connected.

  In the air conditioner 1 having the above-described configuration, a cooling operation mode and a heating operation mode can be set as operation modes by a remote controller (not shown). Further, the remote controller can perform switching of the operation mode, operation stop, indoor temperature setting, indoor fan speed setting, and the like.

  In the cooling operation mode, as indicated by solid arrows, the refrigerant discharged from the compressor 6 is sequentially transferred from the four-way switching valve 7 to the outdoor heat exchanger 8, the expansion valve 10, and the indoor heat exchanger 4. A cooling cycle is performed in which the flow returns to the compressor 6 through the four-way selector valve 7 and the accumulator 11. That is, the outdoor heat exchanger 8 functions as a condenser, while the indoor heat exchanger 4 functions as an evaporator.

  On the other hand, in the heating operation mode, the four-way switching valve 7 is switched, and the refrigerant discharged from the compressor 6 is transferred from the four-way switching valve 7 to the indoor heat exchanger 4 as indicated by a broken line arrow. , A heating cycle is performed in which the fuel flows sequentially to the expansion valve 10 and the outdoor heat exchanger 8 and returns to the compressor 6 through the four-way switching valve 7 and the accumulator 11. That is, the indoor heat exchanger 4 functions as a condenser, while the outdoor heat exchanger 8 functions as an evaporator.

  As shown in FIG. 1, the outdoor unit 3 is equipped with a control device 14 that controls various operations of the air conditioner 1. As shown in FIG. 2, the compressor 14, the four-way switching valve 7, the expansion valve 10, the indoor fan 5 and the outdoor fan 9 are connected to the control device 14. However, in practice, the drive unit is connected. Furthermore, an outdoor heat exchanger temperature sensor T1, an outdoor air temperature sensor T2, an indoor heat exchanger temperature sensor T3, and an indoor temperature sensor T4 are connected to the control device 14.

  The control device 14 includes a microcomputer, an input / output circuit, and the like, and includes a command from the remote controller 15 (such as an operation start command and an indoor temperature setting command) and an outdoor temperature detected by the outdoor heat exchanger temperature sensor T1. Based on the heat exchanger temperature, the outdoor air temperature detected by the outdoor air temperature sensor T2, the indoor heat exchanger temperature detected by the indoor heat exchanger temperature sensor T3, and the indoor temperature detected by the indoor temperature sensor T4, The operation of the air conditioner 1 is controlled by performing arithmetic processing, determination processing, and the like.

  That is, in the first embodiment, the control device 14 functions as the pump-down operation control unit 14a, the operation frequency limiting unit 14b, and the time measuring unit 14c.

  Here, the outdoor heat exchanger temperature sensor T <b> 1 is installed in the outdoor heat exchanger 8 and detects the temperature of the outdoor heat exchanger 8. The outdoor temperature sensor T2 is installed in the outdoor unit 3 and detects the outdoor temperature. The indoor heat exchanger temperature sensor T3 is installed in the indoor heat exchanger 4 and detects the temperature of the indoor heat exchanger 4. The indoor temperature sensor T4 is installed in the indoor unit 2 and detects the indoor temperature.

  In the above configuration, when refrigerant leaks in the indoor unit 2 or when the air conditioner 1 is moved or repaired, the pump-down operation is performed to collect the refrigerant. At that time, air may be mixed into the gas line side where the gas side shut-off valve 13 is interposed for some reason such as cracks in the piping or incorrect procedure. In this state, when the pump-down operation is continued, the internal temperature of the compressor 6 rises by sucking and compressing a large amount of air. And if it becomes more than the ignition temperature of the lubricating oil in the compressor 6, the compressor 6 may be damaged.

  In the first embodiment, as described below, the operation frequency of the compressor 6 (hereinafter simply referred to as a frequency) after the pump-down operation is substantially finished is limited so that the pump-down operation is performed. An increase in the internal temperature of the compressor 6 due to continued for a long time is prevented.

  As described above, when refrigerant leaks in the indoor unit 2 or when the air conditioner 1 is moved or repaired, for example, the operation / stop button 16 ( 2) is pressed for a long time, and the controller 14 is instructed to start forced operation. Then, the liquid side closing valve 12 is closed, while the gas side closing valve 13 is opened. Then, the expansion valve 10 is fully opened and the four-way switching valve 7 is switched to the cooling operation side by the pump-down operation control unit 14a of the control device 14. Thereafter, the compressor 6 is driven at a predetermined frequency (for example, 50 Hz), and a pump-down operation for collecting the refrigerant on the indoor unit 2 side to the outdoor unit 3 side through the gas line is performed.

  At the same time, the operation frequency restriction processing operation of the compressor as described in detail below is performed by the operation frequency restriction unit 14b of the control device 14.

  FIG. 3 is a flowchart of the operation frequency restriction processing operation of the compressor that is executed under the control of the operation frequency restriction unit 14b. Hereinafter, the operation frequency restriction processing operation of the compressor will be described with reference to FIG. As described above, after the operation / stop button 16 is pressed and commanded to start forced operation, the liquid side shut-off valve 12 is closed while the gas side shut-off valve 13 is opened. Frequency limit processing starts.

  In step S1, the four-way switching valve 7 is correctly switched to the cooling operation side, and it is determined whether or not the operation mode is set to the cooling operation mode. As a result, if the operation mode is the cooling operation mode, the process proceeds to step S2. In step S2, for example, by referring to a pump-down operation flag or the like, it is determined whether or not the pump-down operation is being performed. As a result, if the pump-down operation is being performed, the process proceeds to step S3. If not, the process returns to step S1. In step S3, it is determined whether or not an elapsed time t after the compressor 6 is driven (after the forced operation is started) has become equal to or longer than a preset set time t0 (for example, 150 seconds). As a result, if it is equal to or longer than the set time t0, the process proceeds to step S4. Otherwise, the process returns to step S1.

  Thus, it is determined whether or not the cooling cycle is stable by detecting that the operation of the compressor 6 in the cooling operation mode is continuously executed for the set time t0 or more. And if it judges that the said cooling cycle is stable, it will transfer to the next step.

In step S4, a value obtained by subtracting the indoor heat exchanger temperature T _EV from the indoor temperature _TL is preset based on the detection signal from the indoor temperature sensor T4 and the detection signal from the indoor heat exchanger temperature sensor T3. It is determined whether or not the temperature is lower than the set temperature T0 (for example, 4 ° C.). As a result, if the temperature becomes lower than the set temperature T0, the process proceeds to step S5. In step S5, the time measuring unit 14c is activated to start measuring the elapsed time _tT0 from when " _TL - _TEV <T0". In step S6, it is determined whether or not the elapsed time _tT0 has reached or exceeded a preset time t1 (for example, 240 seconds). As a result, when the set time t1 is exceeded, the process proceeds to step S7.

Thus, by detecting that the state in which the difference between the indoor temperature T _L and the indoor heat exchanger temperature T _EV is below the set temperature T0 has continued the set time t1 or more, the indoor heat exchanger 4 It is determined that heat exchange is not performed and the pump-down operation is substantially finished. Then, the process proceeds to the next stage.

  In step S7, the upper limit frequency Fmax of the compressor 6 is limited to a preset set frequency F1 (for example, 14 Hz). After that, a lamp is turned on to inform the operator that the pump-down operation has ended.

  In this way, the upper limit frequency Fmax of the compressor 6 after determining that the pump-down operation has substantially ended is limited to the set frequency F1. Therefore, if the set frequency F1 is set to a frequency (for example, 14 Hz) lower than the frequency during the pump-down operation (for example, 50 Hz), the pump-down operation is continued after the pump-down operation is substantially finished. The frequency of the compressor 6 is reduced, and the suction amount of the compressor 6 is reduced. For this reason, even if air is mixed in the refrigerant, an increase in the internal temperature of the compressor 6 is suppressed.

  In step S8, whether or not the elapsed time t after the compressor 6 is driven (after the forced operation is started) is equal to or longer than a preset set time t2 (> t0) (for example, 15 minutes). Is determined. As a result, when the set time t2 is reached, the operation frequency restriction processing operation of the compressor is finished.

  Then, with the compressor 6 operating at the upper limit frequency F1, the operator closes the gas side shut-off valve 13 and operates the operation / stop button 16 provided on the main body of the indoor unit 2 to compress the compressor. When the machine 6 is stopped, or when the controller 14 stops the forced operation because the elapsed time from the start of the forced operation reaches the forced stop time, the pump-down operation is completely finished.

  Here, even if it is determined that the pump-down operation is substantially finished, the operation of the compressor 6 is continued by limiting the upper limit frequency Fmax of the compressor 6 to the set frequency F1 as follows. Depending on the reason. That is, as described above, during the pump down operation, the compressor 6 is driven with the gas side shut-off valve 13 being opened. For this reason, if it is determined that the pump-down operation has substantially ended and the compressor 6 is immediately stopped, the recovered refrigerant flows back through the gas-side shut-off valve 13 that is open. is there.

  Although not described in detail because it becomes complicated, in step S8, while waiting for the elapsed time t after the compressor 6 is driven to be equal to or longer than the set time t2, the above steps S1 to S3 are performed. It is monitored whether all the conditions are satisfied, and when any of the above conditions is not satisfied, the restriction of the upper limit frequency Fmax of the compressor 6 to the set frequency F1 is interrupted, and the process returns to step S1. It is like that.

  As described above, in the first embodiment, the control device 14 is configured to function as the pump-down operation control unit 14a, the operation frequency limiting unit 14b, and the time measuring unit 14c. When the controller 14 is instructed to start the pump-down operation, the pump-down operation control unit 14a causes the pump-down operation in which the refrigerant on the indoor unit 2 side is recovered to the outdoor unit 3 side through the gas line. Is done.

At the same time, as the first stage of the operation frequency restriction start condition by the operation frequency restriction unit 14b of the control device 14, the operation mode is the cooling operation mode, the pump down operation is being performed, and the compressor 6 is turned on. When the condition that the elapsed time t is equal to or longer than the set time t0 is satisfied, the process proceeds to the second stage. Then, as a second stage, an elapsed time t _T0 after the value of “indoor temperature T _L −indoor heat exchanger temperature T _EV ” is lower than the set temperature T0 and becomes “ _TL− T _EV <T0”. When the condition that becomes equal to or longer than the set time t1 is satisfied, it is determined that the indoor heat exchanger 4 is not performing heat exchange and that the pump-down operation is substantially completed. The upper limit frequency Fmax of the compressor 6 is limited to the set frequency F1 (<frequency during pump-down operation).

  Therefore, even when the pump-down operation is continued even after the pump-down operation is substantially finished, the suction amount of the compressor 6 is reduced and even if air is mixed in the refrigerant, An increase in the internal temperature of the compressor 6 can be suppressed. As a result, it is possible to prevent damage to the compressor 6 due to air mixing during the pump-down operation.

Furthermore, when the elapsed time _tT0 from when “ _TL − _TEV <T0” becomes equal to or longer than the set time t1, that is, the state in which the indoor heat exchanger 4 is not performing heat exchange is set time t1 ( For example, when it continues for 240 seconds = 4 minutes) or more, it is determined that the pump-down operation has substantially ended. Here, the pump-down operation time is usually about 2 minutes. Therefore, it is possible to reliably and correctly determine that the pump-down operation has substantially ended, and it is possible to improve reliability.

Further, after the condition of the second stage is established and the upper limit frequency Fmax of the compressor 6 is limited to the set frequency F1, “indoor temperature T _L −indoor heat exchanger temperature T _EV ≧ set temperature T0”. However, the upper limit frequency Fmax of the compressor 6 is continuously limited to the set frequency F1 until the elapsed time t after the compressor 6 is driven becomes equal to or longer than the set time t2. Therefore, even if the refrigerant that has been temporarily recovered returns to the indoor heat exchanger 4 for some reason, or the indoor temperature sensor T4 or the indoor heat exchanger temperature sensor T3 breaks down, the suction amount of the compressor 6 is reduced. The reliability can be further improved by suppressing the increase in the internal temperature.

  Furthermore, the upper limit frequency Fmax of the compressor 6 is limited to the set frequency F1 when the condition “the elapsed time t after the compressor 6 is turned on is not less than the set time t0” in the first stage is satisfied. . Therefore, it is possible to accurately determine that the cooling cycle during the pump-down operation is stable, and it is possible to reliably and correctly determine that the pump-down operation has substantially ended.

Incidentally, in the first embodiment, based on the value of "the difference between the indoor temperature T _L and the indoor heat exchanger temperature T _EV" in step S4, it is determined a substantial completion of the pump down operation . However, the present invention is not limited to this, and instead of “the difference between the indoor temperature T _L and the indoor heat exchanger temperature T _EV ”, “the outside air temperature detected by the outside air temperature sensor T2 and the outside heat exchanger” It may be determined based on the value of “difference from outdoor heat exchanger temperature detected by temperature sensor T1”.

  Further, in the first embodiment, “determining whether or not the pump down operation is being performed” in step S2 is written as “1” when the pump down operation is started by the pump down operation control unit 14a. The determination is made based on the “pump down operation flag” or the like. However, the present invention is not limited to this, and may be determined based on the position of the four-way switching valve 7 and the frequency of the compressor 6, and is limited to a specific method as long as the pump-down operation can be accurately determined. Not.

  In the first embodiment, as the first stage of the operation frequency restriction start condition, the operation mode is the cooling operation mode, the pump down operation is being performed, and the elapsed time t after the compressor 6 is turned on is It is an essential requirement that three conditions that are equal to or longer than the set time t0 be satisfied. However, the present invention is not limited to this, and it is only necessary to determine that the pump-down operation is stably performed, and determination of the operation mode and determination of the elapsed time t after the compressor 6 is turned on are not necessarily required. is not.

[Second Embodiment]
FIG. 4 is a diagram illustrating peripheral devices connected to the control device 214 included in the air conditioner according to the second embodiment of the present invention. In FIG. 4, the same reference numerals as those in FIG. 2 are assigned to the same components as those in FIG. Also in the following description, the same reference numerals as those of the first embodiment are assigned to the same components as those of the first embodiment.

  The air conditioner is different from the first embodiment in that the air conditioner includes a control device 214 and a pressure sensor 17 connected to the control device 214. The air conditioner includes a refrigerant circuit including a compressor 6, a four-way switching valve 7, an outdoor heat exchanger 8, a pressure reducing mechanism 10, a liquid side closing valve 12, an indoor heat exchanger 4, and a gas side closing valve 13. The provision is the same as in the first embodiment.

  The control device 214 includes a microcomputer, an input / output circuit, and the like, and commands from the remote controller 15 (operation start command, indoor temperature setting command, etc.) and outdoor heat exchange detected by the outdoor heat exchanger temperature sensor T1. The outdoor temperature detected by the outdoor temperature sensor T2, the indoor heat exchanger temperature detected by the indoor heat exchanger temperature sensor T3, the indoor temperature detected by the indoor temperature sensor T4, and the pressure sensor 17. Based on the detected compressor suction pressure, the operation of the air conditioner 1 is controlled by performing arithmetic processing, judgment processing, and the like.

  That is, in the second embodiment, the control device 214 functions as the pump-down operation control unit 14a, the operation frequency limiting unit 214b, and the time measuring unit 214c.

Here, the pressure sensor 17 is attached to a suction pipe between the compressor 6 and the accumulator, and detects the suction pressure P ₁ of the compressor 6.

  In the air conditioner configured as described above, the operation frequency restriction processing operation of the compressor as described in detail below is performed by the operation frequency restriction unit 214b of the control device 214.

  FIG. 5 is a flowchart of the operation frequency restriction processing operation of the compressor executed under the control of the operation frequency restriction unit 214b. Hereinafter, the operation frequency restriction processing operation of the compressor will be described with reference to FIG. The start condition of the operation frequency restriction processing operation of the compressor is the same as that in the first embodiment. In FIG. 5, the same reference numerals as those in FIG. 3 are assigned to the same steps as those in FIG.

When the operation frequency limiting process operation of the compressor is started, after the step S1~S3 is performed, in step S24, based on the detection signal from the pressure sensor 17, the intake pressure P ₁ of the compressor 6 is the atmospheric pressure P _It is determined whether or not it has become ₀ or less. As a result, the suction pressure _{P 1} of the compressor 6 advances to step S25 if below atmospheric pressure _{P 0.} In step S25, the time measuring unit 214c is activated, and time measurement of the elapsed time _tT20 after “P ₁ ≦ P ₀ ” is started. In step S36, it is determined whether or not the elapsed time _tT20 has reached or exceeded a preset time t1 (for example, 240 seconds). As a result, when the set time t1 is exceeded, the process proceeds to step S7. Here, the atmospheric pressure P ₀ may be, for example, a fixed value stored in advance in the control device 214, or a fluctuation value detected by an atmospheric pressure sensor attached to the outdoor unit 3.

Thus, by detecting that the state in which the suction pressure P ₁ becomes lower than the atmospheric pressure P ₀ of the compressor 6 continues set time t1 or more, the suction amount of the compressor 6 is decreased, the pump-down operation Is determined to be substantially complete. Then, the process proceeds to the next stage consisting of steps S7 and S8.

  As described above, in the second embodiment, the control device 214 is configured to function as the pump-down operation control unit 14a, the operation frequency limiting unit 214b, and the time measuring unit 214c. Then, when the controller 214 is instructed to start the pump-down operation, the pump-down operation control unit 14a performs the pump-down operation in which the refrigerant on the indoor unit 2 side is recovered to the outdoor unit 3 side via the gas line. Done.

At the same time, as the first stage of the operation frequency restriction start condition by the operation frequency restriction unit 214b of the control device 214, the operation mode is the cooling operation mode, the pump down operation is being performed, and the compressor 6 is turned on. When the condition that the elapsed time t is equal to or longer than the set time t0 is satisfied, the process proceeds to the second stage. Then, as the second step, when "P ₁ ≦ P _0", and and "P ₁ ≦ P _0" and becomes the elapsed time t _T20 since become more time setting t1 condition is satisfied, the compressor 6 is reduced, and it is determined that the pump-down operation has substantially ended. The upper limit frequency Fmax of the compressor 6 is limited to the set frequency F1 (<frequency during pump-down operation).

  Therefore, even when the pump-down operation is continued even after the pump-down operation is substantially finished, the suction amount of the compressor 6 is reduced and even if air is mixed in the refrigerant, An increase in the internal temperature of the compressor 6 can be suppressed. As a result, it is possible to prevent damage to the compressor 6 due to air mixing during the pump-down operation.

Furthermore, when the elapsed time t _T20 from the above “P ₁ ≦ P ₀ ” becomes equal to or longer than the set time t 1, that is, the state in which the refrigerant suction amount of the compressor 6 is reduced is set time t 1 (for example, 240 seconds). = 4 minutes) If the operation continues for more than a minute, it is determined that the pump-down operation has substantially ended. Here, the pump-down operation time is usually about 2 minutes. Therefore, it is possible to reliably and correctly determine that the pump-down operation has substantially ended, and it is possible to improve reliability.

Further, once the second stage condition is established and the upper limit frequency Fmax of the compressor 6 is limited to the set frequency F1, the compressor 6 is driven even if “P ₁ > P ₀ ”. The upper limit frequency Fmax of the compressor 6 is continuously limited to the set frequency F1 until the elapsed time t from the time reaches the set time t2. Therefore, even if the refrigerant that has been temporarily recovered returns to the indoor heat exchange 4 for some reason or the pressure sensor 17 breaks down, the suction amount of the compressor 6 is reduced to suppress an increase in the internal temperature. Thus, the reliability can be further improved.

  Furthermore, the upper limit frequency Fmax of the compressor 6 is limited to the set frequency F1 when the condition “the elapsed time t after the compressor 6 is turned on is not less than the set time t0” in the first stage is satisfied. . Therefore, it is possible to accurately determine that the cooling cycle during the pump-down operation is stable, and it is possible to reliably and correctly determine that the pump-down operation has substantially ended.

[Third Embodiment]
FIG. 6 is a diagram illustrating peripheral devices connected to the control device 314 included in the air conditioner according to the third embodiment of the present invention. In FIG. 6, the same reference numerals as those in FIG. 4 are assigned to the same components as those in FIG. Also in the following description, the same reference numerals as those of the constituent parts of the second embodiment are assigned to the same constituent parts of the second embodiment.

  The air conditioner includes a control device 314 that is partially different from the control device 214. The control device 314 functions as a pump down operation control unit 14a, an operation frequency limiting unit 314b, and a time measuring unit 314c.

  FIG. 7 is a flowchart of the operation frequency restriction processing operation of the compressor executed under the control of the operation frequency restriction unit 314b. Hereinafter, the operation frequency restriction processing operation of the compressor will be described with reference to FIG. The start condition of the operation frequency restriction processing operation of the compressor is the same as that in the second embodiment. In FIG. 7, the same reference numerals as those in FIG. 5 are assigned to the same steps as those in FIG.

  That is, the flowchart of the operation frequency restriction processing operation of the compressor of the third embodiment is obtained by replacing steps S24 to S26 of the second embodiment with steps S34 to S36.

At step S34, set based on the detection signal from the detection signal and the pressure sensor 17 from the indoor heat exchanger temperature sensor T3, the value obtained by subtracting the saturation temperature T _S from the indoor heat exchanger temperature T _EV preset It is determined whether or not a value α (for example, 4) is reached. As a result, the value obtained by subtracting the saturation temperature T _S from the indoor heat exchanger temperature T _EV proceeds to step S35 if the set value or more alpha. In step S35, the time measuring unit 314c is activated and time measurement of the elapsed time t _T30 from when “T _EV −T _S ≧ α” is started. In step S36, it is determined whether or not the elapsed time _tT30 is equal to or longer than a preset set time t1 (for example, 240 seconds). As a result, when the elapsed time _tT30 becomes equal to or longer than the set time t1, the process proceeds to step S7. Here, the indoor heat exchanger temperature _TEV is detected by the indoor heat exchanger temperature sensor T3. The saturation temperature T _S corresponds to the suction pressure P ₁ detected by the pressure sensor 17 and is obtained using, for example, a table stored in the control device 314 in advance.

Thus, by detecting that continues state value obtained by subtracting the saturation temperature T _S from the indoor heat exchanger temperature T _EV is equal to or greater than the set value α set time t1 or more, the suction amount of the compressor 6 It is determined that the pump-down operation is substantially finished. Then, the process proceeds to the next stage consisting of steps S7 and S8.

  Therefore, the air conditioner according to the third embodiment has an effect of preventing damage to the compressor 6 and an effect of improving reliability, like the air conditioner according to the second embodiment.

[Fourth Embodiment]
FIG. 8 is a diagram illustrating peripheral devices connected to the control device 414 included in the air conditioner according to the fourth embodiment of the present invention. In FIG. 8, the same reference numerals as those in FIG. 4 are assigned to the same components as those in FIG. Also in the following description, the same reference numerals as those of the constituent parts of the second embodiment are assigned to the same constituent parts of the second embodiment.

  The air conditioner includes a control device 414 that is partially different from the control device 214. The control device 414 functions as a pump down operation control unit 14a, an operation frequency limiting unit 414b, and a time measuring unit 414c.

  FIG. 9 is a flowchart of the operation frequency restriction processing operation of the compressor executed under the control of the operation frequency restriction unit 414b. Hereinafter, the operation frequency restriction processing operation of the compressor will be described with reference to FIG. The start condition of the operation frequency restriction processing operation of the compressor is the same as that in the second embodiment. In FIG. 9, the same reference numerals as those in FIG. 5 are assigned to the same steps as those in FIG.

  That is, the flowchart of the operation frequency restriction processing operation of the compressor of the fourth embodiment is obtained by replacing steps S24 to S26 of the second embodiment with steps S44 to S46.

In the step S44, based on the detection signal from the pressure sensor 17, the set value the absolute value is set in advance of the detected time variation of the slope SL of the suction pressure P ₁ by the pressure sensor 17 beta (e.g. 0.1) It is determined whether or not: As a result, the process proceeds to step S45 if the absolute value of the slope SL of the time variation of the suction pressure P ₁ is below the set value beta. In step S45, timing unit 414c is activated, counting of the elapsed time t _T40 from the absolute value is equal to or less than the set value β of the slope SL of the time variation of the suction pressure P ₁ is started. In step S46, it is determined whether or not the elapsed time _tT40 has reached a preset time t1 (for example, 240 seconds) or more. As a result, when the elapsed time _tT40 becomes equal to or longer than the set time t1, the process proceeds to step S7.

Thus, by detecting that the state in which the absolute value of the slope SL of the time change of the suction pressure P ₁ is equal to or less than the set value β continues set time t1 or more, the suction amount of the compressor 6 is decreased It is determined that the pump-down operation has substantially ended. Then, the process proceeds to the next stage consisting of steps S7 and S8.

  Therefore, the air conditioner according to the fourth embodiment has the effect of preventing damage to the compressor 6 and the effect of improving the reliability, like the air conditioner according to the second embodiment.

  Although specific embodiments of the present invention have been described, the present invention is not limited to the first to fourth embodiments, and various modifications can be made within the scope of the present invention. For example, a modification of the first embodiment applied to the second to fourth embodiments may be an embodiment of the present invention.

DESCRIPTION OF SYMBOLS 1 ... Air conditioner 2 ... Indoor unit 3 ... Outdoor unit 4 ... Indoor heat exchanger 5 ... Indoor fan 6 ... Compressor 7 ... Four-way switching valve 8 ... Outdoor heat exchanger 9 ... Outdoor fan 10 ... Expansion valve 11 ... Accumulator DESCRIPTION OF SYMBOLS 12 ... Liquid side closing valve 13 ... Gas side closing valve 14,214,314,414 ... Control apparatus 14a ... Pump down operation control part 14b ... Operating frequency limiting part 14c, 214c, 314c, 414c ... Time measuring part 15 ... Remote control 16 ... operation / stop button 17 ... pressure sensor L1, L2 ... connection pipe P 1 _... suction pressure SL ... inclination T1 ... outdoor heat exchanger temperature sensor T2 ... ambient temperature sensor T3 ... indoor heat exchanger temperature sensor T4 ... room temperature sensor T _L ... Indoor temperature T _EV ... Indoor heat exchanger temperature T0 ... Set temperature t1 ... Set time

Claims (12)

Compressor (6), four-way switching valve (7), outdoor heat exchanger (8), pressure reducing mechanism (10), liquid side closing valve (12), indoor heat exchanger (4) and gas side closing valve (13 A refrigerant circuit connected by refrigerant pipes in this order, and
An indoor heat exchanger temperature sensor (T3) that is installed in the indoor heat exchanger (4) and detects the temperature of the indoor heat exchanger (4);
An indoor temperature sensor (T4) disposed in the indoor unit (2) for detecting the indoor temperature;
A pump-down operation control unit (14a) that controls at least the compressor (6) and the four-way switching valve (7) in the refrigerant circuit to perform a pump-down operation;
During the pump-down operation by the pump-down operation control unit (14a), the indoor temperature (T _L ) detected by the indoor temperature sensor (T4) and the indoor temperature detected by the indoor heat exchanger temperature sensor (T3). An operating frequency limiter that limits the upper limit value of the operating frequency of the compressor (6) when the value of the difference from the heat exchanger temperature (T _EV ) falls below a preset temperature (T0). (14b) and an air conditioner. In the air conditioner according to claim 1,
The operating frequency limiter (14b)
When the state where the difference between the indoor temperature (T _L ) and the indoor heat exchanger temperature (T _EV ) is lower than the set temperature (T0) continues for a preset time (t1), It is determined that the pump-down operation has ended, and an upper limit value of the operating frequency of the compressor (6) is limited. In the air conditioner according to claim 1 or 2,
The operating frequency limiter (14b)
After limiting the upper limit value of the operating frequency of the compressor (6), the difference value between the indoor temperature (T _L ) and the indoor heat exchanger temperature (T _EV ) is equal to or higher than the set temperature (T 0). Even if it becomes, the said restriction | limiting with respect to the upper limit of the operating frequency of the said compressor (6) is continued, The air conditioner characterized by the above-mentioned. Compressor (6), four-way switching valve (7), outdoor heat exchanger (8), pressure reducing mechanism (10), liquid side closing valve (12), indoor heat exchanger (4) and gas side closing valve (13 A refrigerant circuit connected by refrigerant pipes in this order, and
An outdoor heat exchanger temperature sensor (T1) installed in the outdoor heat exchanger (8) for detecting the temperature of the outdoor heat exchanger (8);
An outdoor temperature sensor (T2) that is disposed in the outdoor unit (3) and detects an outdoor temperature;
A pump-down operation control unit (14a) that controls at least the compressor (6) and the four-way switching valve (7) in the refrigerant circuit to perform a pump-down operation;
During the pump-down operation by the pump-down operation control unit (14a), the outdoor temperature detected by the outdoor temperature sensor (T2) and the outdoor heat exchanger temperature detected by the outdoor heat exchanger temperature sensor (T1). And an operating frequency limiter (14b) that limits the upper limit value of the operating frequency of the compressor (6) when the value of the difference with the temperature falls below a preset temperature (T0) set in advance. Air conditioner characterized by. The air conditioner according to claim 4,
The operating frequency limiter (14b)
When the state where the difference between the outdoor temperature and the outdoor heat exchanger temperature is lower than the set temperature (T0) continues for a preset time (t1) or longer, the pump down operation is completed. An air conditioner characterized in that it is determined to limit the upper limit value of the operating frequency of the compressor (6). In the air conditioner according to claim 4 or 5,
The operating frequency limiter (14b)
Even if the difference between the outdoor temperature and the outdoor heat exchanger temperature becomes equal to or higher than the set temperature (T0) after limiting the upper limit value of the operating frequency of the compressor (6), the compressor An air conditioner characterized in that the above restriction on the upper limit value of the operating frequency in (6) is continued. In the air conditioner according to any one of claims 1 to 6,
The operating frequency limiter (14b)
After the pump down operation control unit (14a) has started the pump down operation for a preset time (t0) or longer, it is limited to the upper limit value of the operating frequency of the compressor (6). An air conditioner characterized in that it is adapted to add. In the air conditioner according to any one of claims 1 to 7,
The pump down operation control unit (14a)
An air conditioner characterized in that the pump-down operation is terminated when the elapsed time from the start of operation of the compressor (6) reaches the forced stop time. Compressor (6), four-way switching valve (7), outdoor heat exchanger (8), pressure reducing mechanism (10), liquid side closing valve (12), indoor heat exchanger (4) and gas side closing valve (13 A refrigerant circuit connected by refrigerant pipes in this order, and
A pressure sensor (17) for detecting the suction pressure (P ₁ ) of the compressor (6);
A pump-down operation control unit (14a) that controls at least the compressor (6) and the four-way switching valve (7) in the refrigerant circuit to perform a pump-down operation;
When it is determined during the pump-down operation by the pump-down operation control unit (14a) that the conditions for completing the pump-down operation are satisfied based on the suction pressure (P ₁ ) detected by the pressure sensor (17). An air conditioner comprising: an operating frequency limiter (214b, 314b, 414b) that limits the upper limit value of the operating frequency of the compressor (6). The air conditioner according to claim 9,
The operating frequency limiter (214b) is configured so that a state in which the suction pressure (P ₁ ) detected by the pressure sensor (17) is equal to or lower than the atmospheric pressure (P ₀ ) is equal to or longer than a preset set time (t1). When it continues, it determines with satisfy | filling the completion conditions of the said pump down driving | operation, The air conditioner characterized by the above-mentioned. The air conditioner according to claim 9,
An indoor heat exchanger temperature sensor (T3) installed in the indoor heat exchanger (4) for detecting the temperature of the indoor heat exchanger (4);
The operating frequency limiter (314b) is configured to set the indoor heat exchanger temperature (TEV) detected by the indoor heat exchanger temperature sensor (T3) and the suction pressure (P ₁ ) detected by the pressure sensor (17). When the state in which the difference from the corresponding saturation temperature (T _S ) is equal to or greater than the preset set value (α) continues for the preset set time (t1), the pump down operation is completed. An air conditioner characterized by determining that the condition is satisfied. The air conditioner according to claim 9,
In the operating frequency limiting unit (414b), the absolute value of the time variation slope (SL) of the suction pressure (P ₁ ) detected by the pressure sensor (17) is less than or equal to a preset set value (β). The air conditioner is characterized in that it is determined that the condition for completing the pump-down operation is satisfied when the state continues for a preset time (t1) set in advance.

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