JP5124404B2 - Air conditioner - Google Patents

Description

  The present invention relates to an air conditioner in which a plurality of outdoor units are connected, and in particular, an air conditioner that is energized and heated with a heater in order to prevent a decrease in oil viscosity and liquid compression due to liquid return that occurs when the compressor is started. About.

The compressor attached to the air conditioner is equipped with an electric heater at the bottom of the compressor to prevent the liquid refrigerant from dissolving in the oil stored in the stopped compressor. The electric heater is energized to keep the compressor temperature high.
In an air conditioner in which a plurality of compressors are provided in the outdoor unit or a plurality of outdoor units are provided, a heater provided in each compressor when the same amount of refrigerant circulates in each compressor There is no problem even if the on / off control is performed collectively. However, if a difference in the amount of circulation occurs, such as when there is a temperature difference between the compressors, and the liquid refrigerant accumulates only in a certain compressor, the heater is adjusted to the compressor that has more liquid refrigerant. If this is controlled, even if only the gas refrigerant is present in the other compressor, it will be preheated and wasteful preheating will occur.

  For example, in the air conditioner described in Patent Document 1, in order to disperse and reduce standby power when a plurality of compressors are preheated by a preheating device, each compressor is provided with a temperature detection device and predetermined. An invention is disclosed that controls energization and shut-off of a preheating device when an upper limit and a lower limit of temperature are detected.

Japanese Patent Laid-Open No. 2003-166761

If the air temperature where the indoor unit is installed is lower than the air temperature where the outdoor unit is installed, the balance pressure of the refrigeration cycle will be the saturation pressure of the air temperature where the indoor unit is installed. Is always in a superheated gas state, and only the gas refrigerant exists in the vicinity of the compressor in the outdoor unit, so that liquid does not accumulate. For this reason, it is not necessary to energize the electric heater attached to the compressor and the accumulator.
Further, when a plurality of outdoor units are provided and are connected apart from each other, each outdoor unit is installed at various ambient temperatures such as the sun, the shade, and the building. Therefore, the case where the air temperature where a certain outdoor unit is installed is high and the air temperature where another outdoor unit is installed is low may occur. In such a case, since the balance pressure of the refrigeration cycle becomes a saturation pressure at a lower air temperature, liquid refrigerant accumulates in the outdoor unit installed on the lower air temperature side, but installed on the higher air temperature side. Only the gas refrigerant is present in the outdoor unit. Therefore, it is not necessary to energize the electric heater attached to the compressor and accumulator attached to the outdoor unit on the high air temperature side.

  However, in the thing of the said patent document 1, it is not fully considered about providing the outdoor unit which has a compressor in several places that a temperature difference produces.

  An object of the present invention is to obtain an air conditioner that appropriately controls heater energization for preventing liquid compression at the time of starting a compressor even when the ambient temperature is different for each outdoor unit.

  In order to achieve the above object, the present invention provides an air conditioner in which a plurality of outdoor units each including a compressor and an outdoor heat exchanger are connected, wherein the plurality of outdoor units compress the compressor. An apparatus preheating device and a detection means for detecting a value related to the temperature inside or outside the outdoor unit, each of the detection values of the detection means in the plurality of outdoor units on the side where the detection value is lower Preheating device control means for controlling the compressor preheating device provided in the outdoor unit to be energized is provided.

  In the above, the detection means may be an outside temperature detection sensor.

  Further, in the above, the detection means may be an outdoor heat exchanger temperature detection sensor.

  Further, in each of the above, each outdoor unit is provided with an accumulator and an accumulator preheating device for heating the accumulator, and the detection value of the detection values in the plurality of outdoor units on the side where the detection value is lower It is good to control by the said preheating apparatus control means so that it may energize with respect to the said accumulator preheating apparatus with which the said outdoor unit was equipped.

  Furthermore, another feature of the present invention is an air conditioner configured by connecting a plurality of outdoor units including a compressor and an accumulator, wherein the plurality of outdoor units includes a compressor preheating device that heats the compressor, An accumulator preheating device that heats the accumulator, a detection unit that detects a value related to the temperature inside or outside the outdoor unit, and a suction pressure detection unit that detects a suction pressure of each compressor. Preheating device control means for calculating a minimum suction pressure equivalent saturation temperature, which is a saturation temperature corresponding to the lowest suction pressure determined from each suction pressure detected by the suction pressure detection means, and each of the plurality of detection means When the detected value is equal to or lower than the saturation temperature corresponding to the minimum suction pressure, the compressor preheating device and the accumulator preheating device provided in the outdoor unit It is to control by the preheating device control unit to electricity.

  ADVANTAGE OF THE INVENTION According to this invention, even when ambient temperature differs for every outdoor unit, there exists an effect which can control appropriately heater energization for preventing the liquid compression at the time of compressor starting.

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

FIG. 1 is a configuration diagram of a refrigeration cycle showing Example 1 of the present invention, which is a multi-room air conditioner in which a plurality of outdoor units and indoor units are connected. In this embodiment, a case where two outdoor units and three indoor units are connected will be described. However, the present invention is not limited to this number.
The refrigeration cycle configurations of one outdoor unit 1a and the other outdoor unit 1b are equivalent. The refrigeration cycle of one outdoor unit 1a is configured by connecting a compressor 3a, an oil separator 4a, a check valve 5a, a four-way valve 6a, an outdoor heat exchanger 7a, an outdoor expansion valve 8a, and an accumulator 9a, Similarly, the other outdoor unit 1b is configured by connecting a compressor 3b, an oil separator 4b, a check valve 5b, a four-way valve 6b, an outdoor heat exchanger 7b, an outdoor expansion valve 8b, and an accumulator 9b. The gas connection pipe and the liquid connection pipe extending from one outdoor unit 1a merge with the gas connection pipe and the liquid connection pipe extending from the other outdoor unit 1b, and are connected to the indoor units 2a, 2b, and 2c. The indoor units 2a, 2b, 2c include indoor heat exchangers 12a, 12b, 12c and indoor expansion valves 13a, 13b, 13c.

  At the bottoms of the compressors 3a, 3b and accumulators 9a, 9b attached to the outdoor units 1a, 1b, compressor preheating devices 10a, 10b (for example, electric heaters) that can heat them and accumulator preheating devices 11a, 11b (for example, , Electric heater, etc.). Further, as the detecting means for detecting the ambient temperature where the outdoor units 1a and 1b are installed, the outdoor air temperature detecting means 15a and 15b are provided in the respective outdoor units, and the compressor preheating devices 10a and 10b and the accumulator are provided. The preheating devices 11 a and 11 b and the outside air temperature detection means 15 a and 15 b are electrically connected to the preheating device control means 14. The preheating device control means 14 is configured to receive an operation stop signal of the air conditioner.

Next, when the operation of the air conditioner of the present invention is stopped, the preheat control device from when the air conditioner is turned on next time until the compressor is started and the operation of the air conditioner is started Will be described.
FIG. 2 is a time chart used for the preheating device control means 14 of the present embodiment. The abscissa indicates the elapsed time, the ordinate indicates the change in the outside air temperature of the outdoor units 1a and 1b, the energization state of each preheating device mounted on the outdoor unit 1a, and the preheating device mounted on the outdoor unit 1b. The energized state is shown. The change with respect to the elapsed time of the outdoor temperature in which one outdoor unit 1a is installed is shown by a solid line, and the change with respect to the elapsed time of the outdoor temperature in which the other outdoor unit 1b is installed is shown with a broken line.

In FIG. 2, since the outdoor air temperature of the outdoor unit 1b is lower until the elapsed time T1, the balance pressure of the air conditioner becomes a saturation pressure corresponding to the outdoor air temperature of the outdoor unit 1b, and liquid refrigerant is contained in the outdoor unit 1b. However, since the outdoor unit 1a is in a state higher than the outdoor air temperature of the outdoor unit 1b, it is higher than the saturation temperature corresponding to the balance pressure of the air conditioner, so that only the gas refrigerant exists. Become.
Thus, if the outdoor temperature is lower than the indoor temperature, the saturation pressure in the refrigeration cycle that determines whether or not the liquid refrigerant accumulates in each outdoor unit is installed at the place of the lowest outdoor temperature. Relatively determined by the outdoor unit. For this reason, in the outdoor unit 1b, the compressor preheating device 10b and the accumulator preheating device 11b are energized to prevent the generation of liquid refrigerant in the compressor 3b and the accumulator 9b. It is necessary to prevent the decrease. On the other hand, since only the gas refrigerant can be present in the outdoor unit 1a, it is possible to prevent liquid compression and oil viscosity reduction at the next start-up even when the compressor preheating device 10a and the accumulator preheating device 11a are not energized. .

  Conventionally, the compressor is equipped with a temperature detection means, and the temperature of the compressor is directly detected to control on / off of the preheating device. Then, when the temperature of the compressor is increased by the preheating device and the outside air temperature is high, Even in a state where only the gas refrigerant is accumulated in the outdoor unit, the preheating device is turned on, which increases the power consumption during standby. Therefore, in order to prevent liquid compression and oil viscosity reduction at the next start-up and reduce power consumption during standby, it is necessary to consider the temperature of the environment in which the outdoor unit is installed as in this embodiment.

  Further, after the elapsed time T1, the outdoor air temperature of the outdoor unit 1a and the outdoor unit 1b is reversed, and the outdoor air temperature of the outdoor unit 1a is low, so the balance pressure of the air conditioner corresponds to the outdoor air temperature of the outdoor unit 1a. Saturation pressure is reached, and liquid refrigerant is stored in the outdoor unit 1a. However, since the outdoor unit 1b is in a state higher than the outdoor air temperature of the outdoor unit 1a, it is higher than the equivalent saturation temperature of the balance pressure of the air conditioner. Since it becomes high, only gas refrigerant exists. For this reason, in the outdoor unit 1a, the compressor preheating device 10a and the accumulator preheating device 11a are energized to prevent the generation of liquid refrigerant in the compressor 3a and the accumulator 9a. It is necessary to prevent the decrease. On the other hand, since only the gas refrigerant can be present in the outdoor unit 1b, it is possible to prevent liquid compression and oil viscosity reduction at the next start-up even when the compressor preheating device 10b and the accumulator preheating device 11b are not energized. It becomes. When the outdoor air temperature in summer is sufficiently high or the ambient temperature of the indoor unit is lower than the outdoor air temperature of the outdoor unit, the outdoor air temperature of one outdoor unit is relative to the outdoor air temperature of the other outdoor unit. Even if the temperature is low, the liquid refrigerant does not accumulate in the outdoor unit having the lower outside air temperature.

  According to the present embodiment, the ambient temperature of each outdoor unit installed in a plurality of units is detected, and the compressor attached to the outdoor unit installed on the low temperature side and the preheating device attached to the accumulator are energized. To control, the preheater of the outdoor unit installed at an ambient temperature almost equal to the saturation temperature corresponding to the balance pressure of the refrigeration cycle is energized, preventing liquid refrigerant accumulation in the compressor and accumulator and starting It is possible to prevent oil viscosity reduction and liquid compression at the time. On the other hand, in the outdoor unit in which the ambient temperature higher than the saturation temperature corresponding to the balance pressure of the refrigeration cycle is detected, only the superheated gas refrigerant exists, so liquid refrigerant does not accumulate in the compressor and accumulator. Prevention of a decrease in oil viscosity and liquid compression during start-up are avoided, and the preheater of the outdoor unit is not energized. Accordingly, it is possible to reduce the standby power amount by half compared to the case where both of the two outdoor units are energized to the preheating device, and power saving of the air conditioner can be achieved.

  Here, the outdoor air temperature detecting means 15a and 15b of the outdoor units 1a and 1b are used to control the energization of the preheating device of each outdoor unit. As shown in FIG. 3, the outdoor unit detects the temperature of each outdoor heat exchanger. Since the outdoor heat exchanger can measure the ambient temperature of the outdoor unit even when the heat exchanger temperature detection means 16a and 16b are installed on the side where the air for heat exchange flows into each outdoor heat exchanger, the air When the harmony device is stopped, the outdoor heat exchanger temperature detection means 16a, 16b and the outside air temperature detection means 15a, 15b show the same value, and the same effect as described above is obtained. Further, since the detection means used for operation control of the refrigeration cycle is used for energization control of the preheating device of each of the outdoor units 1a and 1b, preheating is performed without installing new devices such as the outside air temperature detection means 15a and 15b. Since energization control of the apparatus is possible, the cost of the air conditioner can be reduced.

  FIG. 4 is a refrigeration cycle configuration diagram showing Embodiment 2 of the present invention, and the same reference numerals as those in FIG. 1 denote the same components. In this embodiment, the outdoor units 1a and 1b are provided with suction pressure detection means 17a and 17b for detecting the suction pressure of each outdoor unit in each of the outdoor units 1a and 1b, and the suction pressure detection means 17a and 17b are preheating device control means. The preheating device control means 14 is configured to calculate the minimum suction pressure and the saturation temperature corresponding to the minimum suction pressure from the signals of the suction pressure detection means 17a and 17b. Has been.

Next, the operation of the preheating control device when the air conditioner of the present invention is stopped will be described.
FIG. 5 is a time chart used for the preheating device control means 14 of the present embodiment. The abscissa represents the elapsed time, the ordinate represents the change in the outdoor air temperature of each outdoor unit, the change in the saturation temperature corresponding to the minimum suction pressure, and the energization of the compressor preheating device 10a and the accumulator preheating device 11a attached to the outdoor unit 1a. The state and the energized state of the compressor preheating apparatus 10b and the accumulator preheating apparatus 11b with which the outdoor unit 1b was mounted | worn are shown. The change with respect to the elapsed time of the outdoor temperature in which one outdoor unit 1a is installed is shown by a solid line, the change with respect to the elapsed time of the outdoor temperature in which the other outdoor unit 1b is installed is shown by a broken line, and the saturation temperature corresponding to the lowest suction pressure Is indicated by a two-dot chain line.

  The saturation temperature equivalent to the minimum suction pressure indicates the temperature corresponding to the balance pressure when the air conditioner is stopped, and when the outdoor air temperature of each outdoor unit is higher than the saturation temperature equivalent to the minimum suction pressure, Since the refrigerant state in the outdoor unit is a gas state, it is possible to prevent liquid compression and oil viscosity reduction at the next start-up. That is, until the elapsed time T2, since the outdoor air temperature of the outdoor unit 1a is high and the outdoor air temperature of the outdoor unit 1b is low with respect to the saturation temperature corresponding to the lowest suction pressure, only the outdoor unit 1b is energized to each preheating device. Further, since the outdoor air temperature of the outdoor unit 1a and the outdoor unit 1b is lower than the saturation temperature corresponding to the minimum suction pressure from the elapsed time T2 to T3, the preheating devices of both the outdoor unit 1a and the outdoor unit 1b are energized. Further, from the elapsed time T3 to T4, since the outdoor air temperature of the outdoor unit 1b is high and the outdoor air temperature of the outdoor unit 1a is low with respect to the saturation temperature corresponding to the minimum suction pressure, only the outdoor unit 1a is energized to each preheating device. Furthermore, after the elapsed time T4, since the outdoor air temperature of the outdoor unit 1a and the outdoor unit 1b is higher than the saturation temperature corresponding to the minimum suction pressure, the energization of the preheating devices of both outdoor units is cut off.

  With the configuration as described above, the balance pressure of the plurality of outdoor units 1a and 1b installed is detected by the suction pressure detection means 17a and 17b, and the lowest pressure value detected by the suction pressure detection means 17a and 17b. The preheating device control means 14 calculates the minimum suction pressure equivalent saturation temperature, which is the equivalent saturation temperature of the pressure, and the value of the ambient temperature detection means (for example, the outside air temperature detection means or the outdoor heat exchanger temperature detection means) of each outdoor unit is the lowest. When the temperature is lower than the saturation temperature equivalent to the suction pressure, power is supplied to each preheating device attached to each outdoor unit. When the value of the ambient temperature detection means of each outdoor unit is higher than the saturation temperature equivalent to the minimum suction pressure, it is attached to each outdoor unit. Control is performed to cut off the power to each preheating device. As a result, the preheater is energized only when the temperature is equal to or lower than the saturation temperature corresponding to the balance pressure of the refrigeration cycle, that is, when the liquid refrigerant can be stored in the outdoor unit, and the liquid refrigerant is stored in the compressor and accumulator. Thus, oil viscosity can be prevented from lowering at start-up and liquid compression can be avoided, and the power consumption of the air-conditioning apparatus can be reduced by reducing standby power to the minimum necessary.

The refrigeration cycle block diagram which shows Example 1 of the air conditioning apparatus of this invention. The time chart figure used for the preheating apparatus control means of Example 1 of this invention. The refrigeration cycle block diagram provided with the outdoor heat exchanger temperature detection means instead of the outdoor temperature detection means of Example 1. FIG. The refrigeration cycle block diagram which shows Example 2 of the air conditioning apparatus of this invention. The time chart used for the preheating apparatus control means of Example 2 of this invention.

Explanation of symbols

1a, 1b Outdoor unit 2a, 2b, 2c Indoor unit 3a, 3b Compressor 4a, 4b Oil separator 5a, 5b Check valve 6a, 6b Four-way valve 7a, 7b Outdoor heat exchanger 8a, 8b Outdoor expansion valve 9a, 9b Accumulator 10a, 10b Compressor preheating devices 11a, 11b Accumulator preheating devices 12a, 12b, 12c Indoor heat exchangers 13a, 13b, 13c Indoor expansion valve 14 Preheating device control means 15a, 15b Outside air temperature detection means 16a, 16b Outdoor heat exchanger temperature Detection means 17a, 17b Suction pressure detection means

Claims (4)

In an air conditioner formed by connecting a plurality of outdoor units including a compressor and an outdoor heat exchanger,
The plurality of outdoor units each include a compressor preheating device that heats the compressor, and a detection unit that detects an outside air temperature of the outdoor unit,
When the outside air temperature is to operate the compressor preheater lower than the room temperature, among the plurality of outdoor units, the compression outside air temperature detected by said detecting means is provided in the lowest had chamber outboard motor An air conditioner characterized by comprising preheating device control means for controlling only the machine preheating device to energize.   2. The air conditioner according to claim 1, wherein the detection means is an outside temperature detection sensor.   2. The air conditioner according to claim 1, wherein the detection means is an outdoor heat exchanger temperature detection sensor. The air conditioner according to any one of claims 1 to 3,
Wherein each outdoor unit, the accumulator and accumulator preheating device is provided for heating the accumulator of the plurality of outdoor units, the outside air temperature detected is provided in the lowest had chamber outboard motor by the detection means and the An air conditioner controlled by the preheating device control means so as to energize the accumulator preheating device.

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