JP2008209022A - Multi-air conditioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multi-air conditioner capable of preventing shortage of an oil level of a compressor in defrosting operation. <P>SOLUTION: This multi-air conditioner has an outdoor machine unit 10 having the compressor 11 compressing a refrigerant, and a plurality of indoor machine units 20 having an indoor heat exchanger 21, and outputs a control command for controlling output of the compressor 11 of the outdoor machine unit 10 from the respective indoor machine units 20, and has a control part for performing the defrosting operation for heating an outdoor heat exchanger 13 provided in the outdoor machine unit 10. The control part performs refrigerant recovery operation for recovering the refrigerant gathered in the outdoor heat exchanger 13 provided in an outdoor machine to the compressor 11 when starting the defrosting operation. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a multi-type air conditioner that includes a plurality of indoor unit units that eject conditioned air by air conditioning operation (cooling operation, heating operation, and dehumidifying operation) and that can perform different operation control for each indoor unit.

An air conditioner that performs indoor air conditioning and dehumidification (hereinafter collectively referred to as “air conditioning”) has a configuration in which an indoor unit and an outdoor unit are connected by a refrigerant pipe and an electrical wiring. Such an air conditioner uses a heat pump that forms a refrigerant circulation circuit with a compressor, an outdoor heat exchanger, a throttle mechanism, an indoor heat exchanger, and a four-way valve as main components, and is sent from the compressor. The desired air conditioning operation is performed by switching the circulation direction of the refrigerant by operating the four-way valve.
In such an air conditioner, a single type of configuration in which one indoor unit is connected to a set of outdoor unit and a configuration in which a plurality of indoor unit units each enabling independent operation control are connected There are multiple types.
During the heating operation, the defrost operation is performed to prevent the outdoor heat exchanger from freezing. In the defrost operation, the refrigerant flows in the cooling cycle direction, and the high-temperature refrigerant flows through the outdoor unit, thereby increasing the temperature of the frozen heat exchanger. The compressor speed and the opening of the electronic expansion valve (EEV) are set in a range in which the frozen heat exchanger is melted and the refrigerant flow noise can be allowed.
Japanese Patent No. 2503633

In the case of the multi air conditioner described above, there are many connected indoor units and the total piping length is also long. For this reason, the refrigerating machine oil contained in the refrigerant cannot be recovered by the compressor, and the compressor may run out of oil during the defrost operation. This is more noticeable as the outside air temperature is lower.
As a result, there is a possibility of causing wear and damage inside the compressor.

  This invention is made | formed in view of the said situation, and it aims at providing the multi-type air conditioning apparatus which can prevent the oil level cut | off of a compressor at the time of a defrost operation.

  The invention according to claim 1 is a multi-type air conditioner comprising an outdoor unit provided with a compressor for compressing refrigerant and a plurality of indoor unit provided with an indoor heat exchanger. A control unit that performs a defrost operation for heating the outdoor heat exchanger included in the refrigerant, and the control unit performs a refrigerant recovery operation for recovering the refrigerant accumulated in the outdoor heat exchanger to the compressor during the defrost operation. It is characterized by performing.

  According to such a multi-type air conditioner, the refrigeration oil mixed in the refrigerant is recovered by the compressor prior to the original defrost operation.

  According to a second aspect of the present invention, in the multi-type air conditioner according to the first aspect, the control unit can discharge the refrigerant from the outdoor heat exchanger with the rotation speed of the compressor as the refrigerant recovery operation. The rotation speed of the electronic expansion valve that restricts the refrigerant flow path is set to be larger than that of the normal defrost operation.

  According to such a multi-type air conditioner, even if the opening of the electronic expansion valve is opened, the refrigerant flow noise does not increase because the refrigerant circulation is small.

  According to a third aspect of the present invention, the control unit performs the refrigerant recovery operation until a value obtained by subtracting the liquid phase side refrigerant temperature of the outdoor heat exchanger from the suction pipe temperature of the compressor becomes less than 0 ° C. It is characterized by performing.

According to such a multi-type air conditioner, the control unit can determine that the following expression (1) is satisfied as a condition for determining that the refrigerant recovery is completed.
Compressor suction pipe temperature−outdoor heat exchanger liquid phase side refrigerant temperature <0 ° C. (1)

  According to a fourth aspect of the present invention, the refrigerant recovery operation is performed until a value obtained by subtracting an average value of the indoor heat exchanger temperature included in the indoor unit being operated from the suction pipe temperature of the compressor is less than 0 ° C. It is characterized by performing.

According to such a multi-type air conditioner, the control unit can determine that the following expression (2) is satisfied as a condition for determining that the refrigerant recovery is completed.
Compressor suction pipe temperature-indoor heat exchanger temperature average value of the operating indoor unit <0 ° C (2)

  According to the multi-type air conditioning apparatus of the present invention, it is possible to prevent the oil level of the compressor from being cut during defrost operation, and it is possible to prevent wear and damage inside the compressor.

  Hereinafter, an embodiment of a multi-type air conditioner according to the present embodiment will be described with reference to the drawings. FIG. 1 is an explanatory diagram illustrating an example of the overall configuration of a multi-type air conditioner. This multi-type air conditioner includes an outdoor unit 10 and a plurality of indoor unit units 20 (two indoor unit units 20A and 20B in the illustrated example) connected to the outdoor unit 10. Configured. The indoor unit 20 and the outdoor unit 10 are connected by a refrigerant pipe 30 through which a refrigerant flows, electric wiring (not shown), and the like.

  The outdoor unit 10 includes a compressor 11 that compresses and sends out a refrigerant, a four-way valve 12 that switches a circulation direction of the refrigerant, an outdoor heat exchanger 13 that exchanges heat between the refrigerant and the outside air, and a throttling mechanism. The functioning electronic expansion valve 14 is a main component, and further, the muffler 15 disposed in the discharge side piping of the compressor 11 for the purpose of silencing, and the suction pipe piping of the compressor 11 for the same purpose of silencing. The suction muffler 16 is provided, and an outdoor control unit (control unit) 17 that performs various operation controls is provided. In addition, the outdoor unit 10 is provided with devices such as an outdoor fan, a receiver, a service valve, and a strainer (not shown) and sensors such as a temperature sensor.

The indoor unit 20 is configured such that a casing and other devices such as an indoor fan (not shown) are housed in the casing in addition to the indoor heat exchanger 21 and the indoor control unit (control unit) 22. The indoor heat exchanger 21 includes a two-phase flow part temperature sensor 23 that detects the temperature of the two-phase flow part, a gas phase part temperature sensor 24 that detects the temperature on the gas phase side, and an indoor air suction temperature sensor 25. The temperature data detected by these temperature sensors is input to the indoor control unit 22. Here, the two-phase flow part temperature sensor 23 is a temperature sensor attached to the intermediate part of the path of the indoor heat exchanger 21, and detects the pressure saturation temperature in the two-phase flow part. The indoor air suction temperature sensor 25 detects the temperature of the indoor air sucked into the indoor unit 20, that is, the temperature of the indoor air to be air-conditioned from now on, so that an appropriate position in the flow path from the suction port to the indoor heat exchanger 21 is detected. It is a temperature sensor attached to.
In addition, A and B attached to each code | symbol in a figure shall be used only when distinguishing and explaining two indoor unit units.

  This indoor unit 20 guides indoor air sucked by an indoor fan to the indoor heat exchanger 21 and passes it through, and the conditioned air heat-exchanged with the refrigerant supplied from the outdoor unit 10 described above into the room. It is configured to blow out. Also, the two indoor unit units 20A and 20B are installed in different air-conditioning target rooms, and are configured to be capable of different operation control depending on the situation of each room. Here, the different operation control means that either one of the cooling operation or the heating operation is selected, and the operation control corresponding to the air conditioning load different for each room is performed, and the two indoor unit 20A, 20B does not perform different air conditioning operations at the same time as in the heating operation and the cooling operation.

The two indoor unit units 20A and 20B are connected to refrigerant pipes 30A and 30B branched by a pipe connector 31 and a header 32 in the outdoor unit 10, respectively. In addition, each refrigerant pipe 30A, 30B in the outdoor unit 10 is provided with electronic expansion valves 14A, 14B that operate independently between the outdoor heat exchanger 13 and the indoor unit 20A, 20B. ing.
In the outdoor unit 10 described above, the intake pipe sensor 11a and the discharge pipe sensor 11b of the compressor 11, the outdoor heat exchange sensor 13a provided on the liquid phase side of the outdoor heat exchanger 13, and the outside air temperature are detected. The detected temperature is input to the outdoor control unit 17.

Below, the effect | action of the multi-type air conditioning apparatus of the structure mentioned above is divided and demonstrated in each case at the time of heating operation and air_conditionaing | cooling operation.
First, the air conditioning operation during the heating operation will be described together with the refrigerant flow indicated by arrows in the drawing. The heating operation and the cooling operation are selectively switched according to the flow direction of the refrigerant that changes depending on the operation of the four-way valve 12.

  The refrigerant that has been compressed into high-temperature and high-pressure gas by the compressor 11 passes through the muffler 15 and the four-way valve 12 and is guided to the header 32. The gaseous refrigerant is further guided from the header 32 to the indoor heat exchanger 21 of the indoor unit 20 and exchanges heat with the indoor air to dissipate heat. The high-temperature and high-pressure liquid refrigerant condensed by this heat release is reduced in pressure when passing through the electronic expansion valve 14 to become a low-temperature and low-pressure gas-liquid two-phase refrigerant and flows into the outdoor heat exchanger 13.

When the gas-liquid two-phase refrigerant flowing into the outdoor heat exchanger 13 passes through this heat exchanger, it exchanges heat with outdoor air (hereinafter referred to as “outdoor air”), absorbs heat, evaporates, and evaporates to a low temperature. It becomes a low-pressure gas refrigerant. This gaseous refrigerant passes through the four-way valve 12 and the suction muffler 16 and is sucked into the compressor 11, and then circulates in the refrigeration cycle of the multi-type air conditioner while repeating state changes in the same process.
In such heating operation, when the indoor unit 20A, 20B is operated simultaneously under different air conditioning loads, the refrigerant circulation amount distributed to both units is adjusted by the opening degree of the electronic expansion valves 14A, 14B. . In addition, about the indoor unit 20 in operation stop, the electronic expansion valve 14 connected to the unit is fully closed or slightly opened.

Next, the cooling operation will be briefly described. This cooling operation is performed by operating the four-way valve 12 and switching the refrigerant circulation direction from the above-described heating operation.
In this cooling operation, the refrigerant flow from the compressor 11 to the four-way valve 12 is the same as that in the heating operation. However, the high-temperature and high-pressure gas-phase refrigerant that has exited the four-way valve 12 is guided to the outdoor heat exchanger 13 and the outdoor operation. Exchange heat with air. By this heat exchange, the high-temperature and high-pressure gaseous refrigerant gives heat to the outdoor air to be condensed and liquefied, and becomes a high-temperature and high-pressure liquid refrigerant. The liquid refrigerant is depressurized by passing through the electronic expansion valve 14 to become a low-temperature and low-pressure gas-liquid two-phase refrigerant, and is sent again to the indoor heat exchanger 21 of the indoor unit 20 through the refrigerant pipe 30.

The low-temperature and low-pressure gas-liquid two-phase refrigerant exchanges heat with the indoor air in the indoor heat exchanger 21, removes heat from the indoor air to be air-conditioned, cools the indoor air, and evaporates and evaporates itself to reduce the temperature. It becomes a low-pressure gas refrigerant.
This gaseous refrigerant passes through the header 32, the four-way valve 12, and the suction muffler 16, and is again sucked into the compressor 11, and thereafter circulates in the refrigeration cycle of the multi-type air conditioner while repeating state changes in the same process.

Next, defrost control by the outdoor control unit 17 will be described below.
A predetermined operation time elapses during the heating operation, and the outdoor heat exchanger tube sensor temperature TOPL and the outdoor temperature sensor 18 detected by the outdoor heat exchanger 13a attached to the pipe of the outdoor heat exchanger 13 of the outdoor unit 10 are used. When the detected outside temperature sensor temperature TO reaches a predetermined temperature, the defrost control is started, and when the outdoor heat exchanger tube sensor temperature TOPL rises to a predetermined temperature, a normal operation is performed.

In the above-described multi-type air conditioner, conditions from the start to the end of the defrost control will be described below.
[1] Start condition The condition for entering defrost control (defrost condition) is when all of the following conditions are satisfied. The determination is made separately for <1> normal operation and <2> defrost acceleration operation. Here, at the time of the defrost promotion operation, as shown in the defrost end condition [5] (b), it means that the previous defrost end is the end of the defrost after the defrost time of 10 minutes. Normal operation means other than the above. In addition, normal operation is performed when the power is turned on and after switching from full stop, abnormal stop, cooling operation to heating operation. In addition, when the defrost promotion operation is finished, the next defrost is set to the normal operation.
<1> Normal operation (a) Operation mode: Heating (b) After start of operation or after defrost control: 40 minutes have elapsed (computed operation cumulative time other than outdoor rotation speed 0 rps)
(C) Temperature of TOPL: Continued for 3 minutes after 37 minutes have passed and is below −2 ° C. (limited to actual operation of the compressor)
(D) Temperature of (TO-TOPL): 0.44 × TO + A ° C. or higher (e) During actual compressor operation However, the temperature of (d) is read after (b) has elapsed.

(F) After all the conditions (a) to (e) are satisfied, the upper limit of the multi-command rotation speed is set to 40 rps, and the defrost operation is performed 180 seconds after the outdoor rotation speed and the Inv rotation speed first coincide with each other. .
<2> Defrost accelerated operation (a) Operation mode: Heating (b) 40 minutes have elapsed after completion of defrost (cumulative operation cumulative time other than outdoor rotation speed 0 rps)
(C) During actual compressor operation (d) After all the conditions (a) to (c) are satisfied, the upper limit of the multi-command rotation speed is set to 40 rps, and the outdoor rotation speed and the Inv rotation speed are first matched 180 Perform defrosting operation after 2 seconds.

[2] The number of times the multi-command rotation speed during heating is changed to 0 rps is counted, and if it becomes 10 or more, defrost control is performed when all of the following conditions are satisfied.
(The number of stops due to the activation of the outdoor protection function is not counted.)
<1> During normal operation (a) Operation mode Heating (b) 40 minutes after starting operation or after defrost control ends (accumulated operation time of compressor other than outdoor rotation speed 0 rps)
(C) Temperature of TOPL 3 minutes after 37 minutes have passed and -2 ° C or lower (d) Compressor during actual operation (e) TO ≤ 3 ° C
(F) After satisfying all the above conditions (a) to (e), the upper limit of the multi-command rotation speed is set to 40 rps, and the defrosting operation is performed 180 seconds after the outdoor rotation speed and the Inv rotation speed first coincide with each other. .
This is a countermeasure against the fact that the defrost control is not repeatedly performed when the air conditioner is installed in a room with a small load.
<2> Follow [1] <2> during defrost acceleration operation.
[3] The multi-command rotation speed count of 0 rps and the accumulated time during heating are reset in the following cases. (Return to 0 times)
(A) When defrost control is performed (b) When operation mode is changed (c) When stop signals are received from all indoor controls (when all stops)
(D) When power is turned on

[4] Control contents The operation of each actuator during defrost control is as shown in FIG.
At the start of the defrost operation, the refrigerant recovery operation (symbol A) is performed. At this time, the opening degree of the electronic expansion valve (EEV) 14 of each indoor unit 20 in operation is increased (X3 pulse), and the compressor 11 rotation speed is set to the rotation speed (R3 rps) at which the refrigerant can be recovered. The compressor rotation speed R3 and the EEV opening X3 are values calculated in advance from the number of indoor units to be operated so as to achieve a flow rate necessary to satisfy the refrigerant flow velocity for recovering oil.

The end of the refrigerant recovery operation, that is, the timing for shifting from the R3 rps and X3 pulse to the R1 rps and X1 pulse is determined from the following conditions. However, the determination is made from 30 seconds after the start of the defrost operation.
When TCS-TOPL <0 ° C. The above-described determination condition (temperature) may be changed depending on the value of the external temperature sensor temperature TO.

  These values are shown on the Mollier diagram of FIG. During the defrost operation, which is essentially a cooling cycle, the suction pipe temperature TCS of the compressor 11 is lower than the TOPL before being depressurized by the electronic expansion valve (EEV) 14, so the difference between TSC and TOPL (TCS-TOPL) is Less than zero. The difference between TCS and TOPL (TCS-TOPL) being greater than zero means that the subcooling region of the outdoor heat exchanger 13 is large and liquid refrigerant containing refrigeration oil is accumulated. Therefore, when these differences are lower than 0 ° C., it is determined that the refrigerant recovery is finished.

In addition, you may determine by the suction superheat degree on condition that the following (3) Formula is satisfied.
TCS-indoor heat exchanger temperature average value (TIPave) <0 ° C. (3) included in the indoor unit 20 during operation

  By setting the EEV to the X1 pulse at the end of the refrigerant recovery operation, the refrigerant flow noise during the defrost operation is suppressed. The compressor speed is increased to a speed commensurate with the thawing of the heat exchanger.

  Further, TOPL ≧ 2 ° C. is determined from 30 seconds after the start of the defrost operation, and when this is established, the refrigerant flow noise is further suppressed by lowering the compressor speed to R2 rps and raising the EEV opening to X2.

[5] End condition The condition for moving from the defrost operation to the defrost end operation is when one of the following items is satisfied. However, the determination is made from 90 seconds after the start of the defrost operation.
(A) Heat exchange liquid tube sensor temperature TOPL 20 ° C. or higher (b) Defrost operation time: 10 minutes after defrost operation start (c) Heat exchange liquid tube sensor temperature TOPL 10 ° C. or higher for 2 minutes

  As described above, according to the multi-type air conditioner of the present embodiment, the refrigerant recovery operation is performed prior to the defrost operation by the outdoor control unit 17, and the refrigerant includes the refrigerating machine oil accumulated in the outdoor heat exchanger 13. Is recovered by the compressor 11. For this reason, it is possible to prevent the oil level from being cut off during the defrost operation, and to prevent wear and breakage inside the compressor.

It is a lineblock diagram showing one embodiment of a multi type air harmony device concerning the present invention. It is a timing chart which shows the defrost driving | operation by the multi type air conditioning apparatus. It is the figure which showed each part temperature in a Mollier diagram and a multi-type air conditioning apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Outdoor unit, 11 ... Compressor, 17 ... Outdoor control part (control part), 18 ... Outside temperature sensor, 20 ... Indoor unit, 22 ... Indoor control part (control part), 23 ... Two-phase flow part temperature Sensor

Claims (4)

An outdoor unit having a compressor for compressing the refrigerant;
In a multi-type air conditioner comprising a plurality of indoor unit units equipped with an indoor heat exchanger,
A controller for performing a defrost operation for heating an outdoor heat exchanger provided in the outdoor unit;
The control unit is a multi-type air conditioner that performs a refrigerant recovery operation of recovering the refrigerant accumulated in the front outdoor heat exchanger to the compressor during the defrost operation.   In the refrigerant recovery operation, the control unit sets the rotation speed of the compressor to a rotation speed at which the refrigerant can be discharged from the outdoor heat exchanger, and sets the opening degree of the electronic expansion valve that throttles the refrigerant flow path to the normal defrosting The multi-type air conditioner according to claim 1, wherein the opening degree is larger than that of the operation.   The said control part performs the said refrigerant | coolant collection | recovery operation until the value which pulled the liquid phase side refrigerant | coolant temperature of the said outdoor heat exchanger from the suction pipe | tube temperature of the said compressor becomes less than 0 degreeC. The multi-type air conditioning apparatus described. The control unit performs the refrigerant recovery operation until a value obtained by subtracting an average value of an indoor heat exchanger temperature included in the indoor unit being operated from an intake pipe temperature of the compressor is less than 0 ° C. Item 3. The multi-type air conditioner according to Item 1 or 2.

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