JP2008209021A - Multi-air conditioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multi-air conditioner capable of preventing high pressure abnormality of a compressor, by properly controlling a heating load. <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 an outdoor control part (a control part) 17 for performing heating overload protective control for preventing an increase in a supercooling area in the indoor heat exchanger 21 by recovering the refrigerant from an indoor machine, by expanding opening of an electronic expansion valve 14 more than the normal, when satisfying a predetermined condition. <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.
In a conventional air conditioner, the temperature of the indoor heat exchange sensor that detects the refrigerant saturation temperature of the indoor heat exchanger during heating operation is monitored, and if the indoor heat exchange sensor temperature exceeds a certain temperature, the compressor speed is reduced. This suppresses the high pressure rise in the indoor unit. (This is called indoor unit high pressure control.)
JP 2005-2991557 A

  In the case of a multi-type air conditioner, the amount of enclosed refrigerant is larger than that of a single-type air conditioner. For this reason, when there is an unconnected indoor unit or when a short pipe is connected, an excess refrigerant is generated during operation. In this state, the indoor heat exchange sensor that detects the refrigerant saturation temperature of the indoor heat exchanger during the heating operation enters the supercooling region, and may not be able to detect an appropriate saturation temperature. As a result, the discharge pressure of the compressor cannot be measured properly, the indoor unit high pressure control described above does not operate, the high pressure side rises abnormally, and the use limit of the compressor is exceeded.

  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 high voltage | pressure abnormality of a compressor by performing heating load control appropriately.

  The invention according to claim 1 is a multi-type air conditioner configured by an outdoor unit including a compressor for compressing a refrigerant and a plurality of indoor unit including an indoor heat exchanger. When the condition is satisfied, the refrigerant is collected from the indoor unit to the outdoor unit by widening the opening of the electronic expansion valve that restricts the refrigerant flow path, thereby increasing the supercooling area in the indoor heat exchanger. A control unit for performing heating overload protection control is provided.

As predetermined conditions, it can be set as the case where suction superheat degree is below a fixed value, and indoor air suction temperature and indoor heat exchanger temperature are above a fixed value. To determine the degree of suction superheat, detect the liquid phase temperature of the suction pipe sensor and outdoor heat exchanger provided on the suction side of the compressor (originally, it is preferable to judge based on the two-phase temperature, not the liquid-phase temperature). This can be determined by the difference in the outdoor heat exchange sensor.
In this state, it is determined that the indoor heat exchange sensor that detects the refrigerant temperature of the indoor heat exchanger easily enters the supercooling region. Moreover, when all of these conditions are satisfied, the process shifts to heating overload protection control, thereby preventing a high pressure abnormality of the compressor and suppressing a decrease in heating feeling.

  According to a third aspect of the present invention, in the multi-type air conditioner according to the first or second aspect, the control unit limits the compressor output so as not to increase during the heating overload protection control. It is characterized by.

  This prevents the discharge pressure of the compressor from becoming high.

  According to a fourth aspect of the present invention, in the multi-type air conditioner according to any one of the first to third aspects, the control unit, when the release condition of the heating overload protection control is satisfied, the compressor Is controlled to gradually increase the output to a specified rotational speed.

  This suppresses a sudden increase in compressor output and prevents the high pressure from rising again.

  According to the multi-type air conditioner of the present invention, even when there is an unconnected indoor unit or a short pipe is connected, the high pressure does not rise abnormally during heating operation and an appropriate load is maintained while maintaining the heating feeling. Control can be performed.

  Hereinafter, an embodiment of a multi-type air conditioner according to the present embodiment will be described with reference to the drawings. The multi-type air conditioner of the present embodiment increases the supercooling region in the indoor heat exchanger by recovering the refrigerant from the indoor unit by expanding the opening of the electronic expansion valve beyond the specified value when a predetermined condition is satisfied. Heating overload protection control is performed.

  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 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 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 place in the flow path from the suction port to the indoor heat exchanger 21 is provided. 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. The two indoor unit units 20A and 20B are installed in different air-conditioning target rooms, and are configured to be able to perform 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 simultaneously, such as heating operation and 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.

  Now, the refrigerant made into a high-temperature and high-pressure gas by the compression of 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, but the high-temperature and high-pressure gas-phase refrigerant that has exited the four-way valve 12 is led 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, heating overload protection control by the outdoor control unit 17 will be described. In the outdoor control unit 17 in the present embodiment, when a predetermined condition is satisfied, the refrigerant is recovered from the indoor unit by widening the opening degree of the electronic expansion valve 14 from the specified value, and the supercooling region in the indoor heat exchanger 21 is recovered. Heating overload protection control is performed to prevent the increase.
The control flow at this time is shown in FIGS. First, the heating operation is performed (step A1), and it is determined whether 5 minutes have passed (step A2). When 5 minutes have elapsed, it is determined whether or not the heating overload protection control start condition is satisfied (step A3). If five minutes have not elapsed, the process returns to step A1.
The heating overload protection control start condition is to satisfy all of the following conditions. By satisfying all of these conditions, the heating feeling is prevented from being lowered.
(A) “Heating and 0 rps” continued for 5 minutes (b) When the difference between the detected temperature (TCS) of the suction pipe sensor 11a and the detected temperature (TOPL) of the outdoor heat exchange sensor 13a is as follows: TCS−TOPL ≦ 2 ° C.
This difference indicates the degree of intake superheat, and when the degree of intake superheat is low, it indicates that the refrigerant is in an excessively operating state.
(C) Heating operation unit (operation mode: heating, indoor command rotation speed: other than 0 rps)
When the detected temperature (TION (i)) of the indoor air suction temperature sensor 25 and the detected temperature (TIP1 (i); indoor heat exchange sensor 1) of the two-phase flow portion temperature sensor 23 satisfy the following conditions even in one room (I is each indoor unit A, B, ...)
TION (i)> 27 ° C
TIP1 (i) ≧ 49 ° C.

When this condition is satisfied, the outdoor control unit 17 starts the heating overload protection control (step B1). When not satisfy | filling, it returns to step A1.
In the heating overload protection control, the following control is performed. First, the following settings are made at the start of control (step B2).
Clear the integrated value of the zone control that is the control of the electronic expansion valve 14 to bring the discharge superheat degree (TDSH) closer to the target temperature range (zone). In the zone control, the opening of the electronic expansion valve 14 is widened more than before the start of the control because the operation is in the direction of reducing the opening of the electronic expansion valve 14 under the condition that the main control works.
• Clear the zone control sampling timer. As a result, the integration of the zone control is not performed and is always cleared (= 0).
-The actual operation rotation speed of the compressor 11 is set as the upper limit rotation speed of this control.

During the control, the following is performed (step B3).
The value of Z2, which is a correction coefficient related to the suction superheat degree of the open loop control that determines the initial opening degree of the electronic expansion valve 14, is increased to Z2 = 1.1. Thereby, the opening degree of the electronic expansion valve 14 is expanded.
-Let the lower limit rotation speed of a compressor be 15 rps, for example. Thereby, it is prevented that a heating feeling falls too much.

Next, it is determined whether or not the heating overload protection control should be canceled (step B4). The following conditions are the release conditions.
・ When the compressor speed is 0 rps ・ When the difference between the detected temperature (TCS) of the suction pipe sensor 11a and the detected temperature (TOPL) of the outdoor heat exchange sensor 13a is as follows: TCS-TOPL> 3 ° C.
When the indoor heat exchange sensor temperature 1 (TIP1 (i)) of all the heating operation units (operation mode: heating, indoor command rotation speed: other than 0 rps) satisfies the following conditions: TIP1 (i) ≦ 46 ° C.
When the detected temperature (TION (i)) of the indoor air suction temperature sensor 25 of all the heating operation units (operation mode: heating, indoor command rotation speed: other than 0 rps) satisfies the following conditions: TION (i) <25 ° C.

  When any one of these conditions is satisfied, a release operation is performed (step C1). If not, the control in step B3 is continued.

In the release operation, the compressor rotational speed is gradually returned to a predetermined rotational speed.
First, it is determined whether the temperature condition of the heating overload protection control start condition is satisfied (step C2). If established, heating overload protection control is started. If not established, the command rotational speed> the upper limit rotational speed is determined (step C3). If NO, the operation shifts to normal operation (step C7). In the case of YES, it is determined that the sampling timer is increased by 1 minute (step C4). In the case of YES, the upper limit rotational speed is increased by 5 rps, and the processing from step C1 is repeated (step C5). In the case of NO, the upper limit rotational speed is maintained (step C6).

As described above, in the multi-type air conditioner of the present embodiment, the refrigerant is recovered from the indoor heat exchanger 21 by appropriately increasing the opening degree of the electronic expansion valve 14 by heating overload protection control. Thereby, even when there is an unconnected indoor unit or a short pipe is connected, it is possible to prevent the high pressure side of the compressor 11 from rising abnormally during heating operation.
Moreover, since the start condition of heating overload protection control is appropriately set, it is possible to prevent the heating feeling from being lowered.
Furthermore, when the heating overload protection control is canceled, the compressor rotational speed is gradually returned to the specified value, thereby suppressing an abrupt increase in compressor output and preventing a high pressure from rising again.

It is a lineblock diagram showing one embodiment of a multi type air harmony device concerning the present invention. It is the flowchart which showed the start conditions of the heating overload protection control by the multi type air conditioning apparatus. It is the flowchart which showed the heating overload protection control by the multi type air conditioning apparatus. It is the flowchart which showed the cancellation | release conditions of the heating overload protection control by the multi type air conditioning apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Outdoor unit, 11 ... Compressor, 13a ... Outdoor heat exchange sensor, 17 ... Outdoor control part (control part), 18 ... Outside temperature sensor, 20 ... Indoor unit, 22 ... Indoor 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 configured by a plurality of indoor unit units including an indoor heat exchanger,
When the predetermined condition is satisfied, the refrigerant is collected from the indoor unit to the outdoor unit by expanding the opening of the electronic expansion valve that restricts the refrigerant flow path, and a supercooling region in the indoor heat exchanger. A multi-type air conditioner including a control unit that performs heating overload protection control that prevents an increase in temperature.   2. The condition for starting the heating overload protection control is that the intake superheat degree of the compressor is not more than a certain value, and the indoor air suction temperature and the indoor heat exchanger temperature are not less than a certain value. Multi-type air conditioner.   The multi-type air conditioner according to claim 1 or 2, wherein the control unit restricts the compressor output from being increased during the heating overload protection control.   The said control part performs control which gradually raises the output of the said compressor to a regular rotation speed, when the cancellation | release conditions of the said heating overload protection control are satisfy | filled. Multi-type air conditioner.

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