JP2008215770A - Air conditioner - Google Patents

Abstract

A conventional method of heating a compressor to suppress the discharge of refrigerating machine oil has a problem of high power consumption.
An air conditioner 100 of the present invention includes a compressor 101, an outdoor heat exchanger 102, an expansion valve 103, an indoor heat exchanger 104, and a four-way valve 112. The detection values of the discharge temperature sensor 105, the shell temperature sensor 106, the outdoor pipe temperature sensor 107, the indoor pipe temperature sensor 109, and the suction temperature sensor 110 are processed by the control device 115, and the drive power supply device is either highly efficient or prevents refrigeration oil discharge. The operation mode is instructed. Since the heat generation is increased by reducing the efficiency of the electric motor without using a heater or the like, wasteful power consumption can be suppressed and the reliability of the compressor 101 can be ensured with an inexpensive configuration.
[Selection] Figure 1

Description

  The present invention relates to a method of driving a compressor in an air conditioner that forms a refrigeration cycle or a heat pump cycle using a refrigerant and a compressor and performs cooling or heating. The present invention provides a technology for preventing refrigerating machine oil from being deteriorated due to the refrigerating machine oil inside the compressor being discharged during the cycle and the lack of refrigerating machine oil.

  In an air conditioner that performs cooling and heating using a refrigeration and a heat pump cycle, refrigeration oil is used as a lubricant for a compressor and a leak prevention material for improving performance. In general, the refrigeration oil uses an oil highly compatible with the refrigerant. When the apparatus is stopped, the refrigerant dissolves in a large amount in the refrigeration oil in the compressor. This is said to be that the refrigerant stagnates in the refrigeration oil. This phenomenon itself may deteriorate the lubricity due to the decrease in the viscosity of the oil, which may cause a failure.

  Also, even if the type and amount of refrigerating machine oil is optimized and the problem due to viscosity drop can be solved, when starting from a sleeping state or when the liquid return to the compressor inlet increases during operation, When the heating degree of the discharged refrigerant cannot be obtained, the refrigerating machine oil inside the compressor is discharged during the cycle, and the lubricity may deteriorate due to the shortage of refrigerating machine oil. As a countermeasure at the time of stagnation start-up, a method has been used for a long time to prevent the refrigerant from being melted by increasing the oil temperature while the compressor is stopped. The heater used for this purpose is called a crankcase heater.

  Conventionally, the crankcase heater is energized while the apparatus is stopped, and is heated even if it is not necessary to turn on the heater (see, for example, Non-Patent Document 1).

  However, a technique for heating only when necessary has been developed from the viewpoint of electricity cost and environmental load (see, for example, Patent Document 1).

  As an example, there is one that detects at least one pair of electrodes in an oil sump of a compressor as in Patent Document 1 and detects the amount of refrigerant melted by detecting a change in AC resistance between the electrodes. In the embodiment, when the refrigerant penetration amount reaches a dangerous concentration, the heater winding is energized to heat up the compressor.

  Also, as a method of heating the compressor during operation in order to separate the refrigerant and the refrigerating machine oil, a coil that self-heats by an induced current is provided at the upper part of the rotor of the compressor motor, and a discharge pipe protrudes inside the coil. (For example, refer to Patent Document 2).

As a countermeasure when the liquid return to the inlet increases during compressor operation and the heating degree of the discharged refrigerant cannot be obtained, the expansion valve is throttled to reduce the refrigerant circulation amount and the liquid return amount to the inlet. In general, this is achieved by ensuring the heating degree of the discharged refrigerant.
Japanese Patent Laid-Open No. 4-241797 JP-A-62-29791 Japan Society of Refrigerating and Air Conditioning Engineers, Elementary Standard Text Refrigerating and Air Conditioning Technology, July 20, 1997, Second Print, P39

However, the conventional method of heating while the compressor is stopped has a problem in that it is somewhat wasted from the viewpoint of electricity cost and environmental load, and the cost of the apparatus is increased. In addition, in the method of providing a coil that self-heats by an induced current, the energy for heat generation is derived from the power supplied to the motor of the compressor, and the compressor is always in operation even when heating is unnecessary. Power will be consumed. In addition, regarding the method of controlling the amount of liquid return to the suction port only with the expansion valve during operation, it has excellent controllability when it is restarted after a short stoppage time or when it is handled during defrosting operation. It is the present situation that it cannot be said that it has.

  In view of this problem, the present invention provides an air conditioner that has an inexpensive configuration, has no wasteful power consumption, prevents the refrigerating machine oil from being discharged into the cycle, and ensures the reliability of the compressor. The purpose is to do.

  In order to solve the above-described conventional problems, the air conditioner of the present invention includes a drive power supply device for driving the compressor, and control means for instructing the drive power supply apparatus to operate patterns, and the control means is usually If the high-efficiency operation mode that places importance on the efficiency of the motor is instructed to the drive power supply device and it is determined that a large amount of compressor refrigeration oil is discharged, the refrigeration oil that operates with the compressor motor efficiency lowered The discharge prevention operation mode is instructed. Thereby, in the refrigerator oil discharge prevention operation mode, the amount of heat generated from the motor of the compressor can be increased, and the degree of heating of the discharged refrigerant can be increased.

  In the air conditioner of the present invention, when the control means instructs the drive power supply device to operate in the refrigeration oil discharge prevention mode, the amount of heat generated from the motor of the compressor can be increased and the heating degree of the discharged refrigerant can be increased. With an inexpensive configuration, it is possible to prevent the discharge of refrigeration oil into the cycle without wasteful power consumption, and to ensure the reliability of the compressor.

  A first invention includes a hermetically sealed compressor incorporating an electric motor, an outdoor heat exchanger, a decompression expander that decompresses and expands a refrigerant, an indoor heat exchanger, and a drive power source for driving the compressor And a control means for instructing an operation pattern to the drive power supply apparatus. The control means usually instructs the drive power supply apparatus to a high efficiency operation mode in which importance is placed on the efficiency of the electric motor. When it is determined that a large amount of refrigerating machine oil is discharged, the instruction is for a refrigerating machine oil discharge preventing operation mode in which the motor efficiency of the compressor is reduced, and the amount of heat generated from the motor is increased. By increasing the degree of heating of the discharged refrigerant, it is possible to prevent the refrigerating machine oil from being discharged into the cycle, and to provide an air conditioner that is highly reliable, inexpensive, and uses less power.

  According to a second invention, in the first invention, when the control means obtains time information from the previous compressor stop until the current start, and when the control means has stopped beyond a predetermined time, the compressor oil discharge Instructs the preventive operation mode, can be determined by a simple algorithm, can prevent the discharge of refrigerating machine oil even if the refrigerant is started from a stagnation state, and during the refrigerating machine oil cycle at the start of the first invention Thus, it is possible to reliably prevent discharge.

  According to a third invention, in the first invention, the control means includes temperature detecting means for the compressor, the outdoor heat exchanger, and the indoor heat exchanger, and the temperature of the compressor is the outdoor heat exchanger and the indoor heat exchanger. When the temperature is lower than a predetermined value, the refrigeration oil discharge prevention operation mode is stored, and when the compressor temperature is higher than the predetermined value, the high efficiency operation mode is stored. The operation mode is instructed, and it is possible to accurately determine the stagnation of the refrigerant with an inexpensive configuration and to reduce wasteful power consumption.

According to a fourth aspect of the present invention, in the first aspect, the control means instructs the refrigerating machine oil discharge prevention operation mode during the defrosting operation, and the cycle of the refrigerating machine oil during the defrosting according to the first aspect of the invention is a simple algorithm. It is possible to reliably prevent discharge into the inside.

  According to a fifth invention, in the first invention, the control means comprises temperature detection means of the discharge pipe or suction pipe of the compressor, the outdoor heat exchanger, and the indoor heat exchanger, and the temperature of the compressor discharge pipe or suction pipe. However, when the temperature becomes lower than a predetermined temperature determined from the temperature of the outdoor heat exchanger or the indoor heat exchanger, the refrigeration oil discharge prevention operation mode is instructed. Thus, it is possible to reliably prevent the refrigerating machine oil from being discharged into the cycle in the first invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 shows a configuration diagram of an air conditioner 100 according to a first embodiment of the present invention. As shown in FIG. 1, the first embodiment of the air conditioner of the present invention includes a compressor 101, an outdoor heat exchanger 102, an expansion valve 103 that is a decompression expander, and an indoor heat exchanger 104. The refrigerant pipes are connected to each other, the refrigerant flow direction is switched by the four-way valve 112, and the indoor space 114 is cooled or heated. In FIG. 1, the refrigerant flows in the direction of the arrow 113 and is in a cooling operation.

  The compressor 101 is provided with a discharge temperature sensor 105, a shell temperature sensor 106 representing the compressor temperature, and an intake temperature sensor 110. An outdoor pipe temperature sensor 107 representing the outdoor heat exchanger is provided for the pipe inside the outdoor heat exchanger 102, and an indoor pipe temperature sensor 109 representing the indoor heat exchanger is provided for the pipe inside the indoor heat exchanger 104. Has been.

  The detection values of the discharge temperature sensor 105, the shell temperature sensor 106, the outdoor piping temperature sensor 107, and the indoor piping temperature sensor 109 are processed by the control device 115, or a high-efficiency operation mode in which the motor efficiency of the compressor is emphasized or the compressor motor Any one of the refrigeration oil discharge prevention operation modes that operate with reduced efficiency is selected, an instruction is sent to the drive power supply device 116, and the drive power supply device 116 supplies power to the compressor 101 in accordance with the instruction.

  If the electric motor is a DC brushless motor, there is an optimum voltage amplitude, waveform, current phase of the rotating magnetic pole and coil, etc. with respect to the load in the high efficiency operation mode. In the refrigerating machine oil discharge prevention operation mode, if the setting deviates from the optimum condition, the efficiency decreases. Therefore, the loss may be set so that the loss increases within a stable rotation range. An inexpensive thermistor is used for each temperature sensor, and the temperature can be detected with a simple circuit.

  As described in the background art above, in the air conditioner 100 according to the first embodiment of the present invention, the refrigerating machine oil in the compressor 101 is easily discharged into the cycle. When the engine oil is started in a state where the refrigerant is stagnation in the machine oil, the ratio of the liquid refrigerant returning to the suction pipe of the compressor 101 is increased during the defrosting operation. In these cases, the degree of heating of the refrigerant discharged from the compressor 101 cannot be obtained, and the saturated gas state is highly compatible with the refrigerating machine oil. Therefore, the refrigerating machine oil is discharged together with the discharge of the refrigerant.

  In the present invention, when the compressor oil is likely to be discharged into the cycle without heating the compressor when stopped, the compressor oil discharge prevention operation is performed to intentionally reduce the motor efficiency of the compressor 101, and the compression is performed. By increasing the amount of heat generated inside the machine, the heating degree of the refrigerant discharged from the compressor 101 is increased. As a result, discharge of refrigeration oil can be prevented, and the reliability of the compressor can be ensured without wasteful power consumption with an inexpensive configuration that does not use a heater.

  Further, the control device 115 determines that the refrigerating machine oil is likely to be discharged into the cycle based on information such as the operation value and the detection values of the discharge temperature sensor 105, the shell temperature sensor 106, the outdoor pipe temperature sensor 107, and the indoor pipe temperature sensor 109. Is accurately determined. As a result, it is possible to reliably prevent the refrigeration oil from being discharged into the cycle with an inexpensive configuration, or to accurately determine the stagnation of the refrigerant and reduce wasteful power consumption.

  For stagnation detection, obtain information on the time from when the compressor stopped last time until it starts this time, and if it is determined that stagnation has occurred after a certain period of time, it is determined that stagnation has occurred. Thus, it is possible to reliably prevent discharge.

  In addition, stagnation is likely to occur when the temperature of the compressor 101 is the lowest, and stagnation becomes loose when the temperature of the outdoor heat exchanger 102 or the indoor heat exchanger 104 is lowered. That is, the discharge temperature sensor 105, the suction temperature sensor 110 or the shell temperature sensor 106 is compared with the detected temperatures of the outdoor pipe temperature sensor 107 and the indoor pipe temperature sensor 109, and the discharge temperature sensor 105, the suction temperature sensor 110 or the shell temperature sensor 106 is compared. When the temperature of the discharge temperature sensor 105, the suction temperature sensor 110, or the shell temperature sensor 106 is higher than the predetermined value, the sleep state is canceled. I can judge.

  According to this discrimination method, the determination can be made more accurately than the determination from the stop time, and wasteful power consumption can be further reduced. The sensor itself is also usually used for controlling the air conditioner and is not provided for the refrigerating machine oil discharge prevention operation, so that it can be configured at low cost.

  Regarding the defrosting operation, the refrigerant returns to the suction pipe of the compressor 101 from the indoor heat exchanger 104 where the four-way valve 112 is switched and the blowing is stopped, so that the liquid return tends to increase. The temperature is lowered, and the resulting discharge refrigerant cannot be heated, and the refrigerating machine oil is discharged. Accordingly, during the defrosting operation, if the refrigeration oil discharge prevention operation mode is set, the discharge of the refrigeration oil during the defrosting can be reliably prevented with a simple algorithm.

  In addition, during operation of the air conditioner 100, the refrigerant liquid that returns to the compressor 101 in a transient situation of restarting the compressor 101, changing the number of revolutions, changing the air volume of the blower, and accompanying control operation of the expansion valve 103. When the amount of return increases, the heating degree of the discharged refrigerant cannot be obtained, and the refrigeration oil may be discharged. At this time, the discharge temperature sensor 105, the suction temperature sensor 110, the outdoor pipe temperature sensor 107, and the detected temperature of the indoor pipe temperature sensor 109 are compared to determine whether the temperature of the discharge pipe or the suction pipe is an outdoor heat exchanger or an indoor heat exchanger. When the temperature is lower than the predetermined temperature determined from the temperature of the refrigerant, in other words, the controller 115 indicates that the heating degree of the discharge refrigerant or the suction refrigerant is not secured and indicates the refrigerator oil discharge prevention operation mode. As a result, it is possible to prevent the refrigerating machine oil from being discharged during the cycle.

  As described above, if the determination is made using the detection temperatures of the discharge temperature sensor 105, the suction temperature sensor 110, the outdoor piping temperature sensor 107, and the indoor piping temperature sensor 109, it is possible to accurately cope with a change in state during operation. it can. Also in this method, the sensor itself is normally used for controlling the air conditioner and is not provided for the refrigerating machine oil discharge prevention operation, so that it can be configured at low cost.

The air conditioner of the present invention has a simple configuration, suppresses wasteful power consumption, prevents the refrigerating machine oil inside the compressor from being discharged, and provides an inexpensive and reliable device. The technology can also be applied to devices such as refrigerators, heat pump water heaters or dehumidifiers. Moreover, it has an effect with respect to the apparatus using the refrigerating machine oil highly compatible with the refrigerant regardless of the kind of the refrigerant.

The block diagram of the air conditioner in Embodiment 1 of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Compressor 102 Outdoor heat exchanger 103 Expansion valve 104 Indoor heat exchanger 105 Discharge temperature sensor 106 Shell temperature sensor 107 Outdoor piping temperature sensor 109 Indoor piping temperature sensor 110 Suction temperature sensor 112 Four-way valve 115 Control device 116 Drive power supply device

Claims (5)

A hermetic compressor incorporating an electric motor, an outdoor heat exchanger, a decompression expander for decompressing and expanding a refrigerant, an indoor heat exchanger, a drive power supply device for driving the compressor, and the drive power supply Control means for instructing the operation pattern to the device, and the control means usually instructs the drive power supply device to a high-efficiency operation mode that emphasizes the efficiency of the electric motor, and discharges a large amount of refrigeration oil from the compressor. When it is determined that the air conditioner is operated, the air conditioner is characterized by instructing a refrigerating machine oil discharge prevention operation mode in which the motor efficiency of the compressor is lowered. 2. The air conditioner according to claim 1, wherein the control unit detects that the compressor has been stopped for a predetermined time, and instructs the refrigerating machine oil discharge prevention operation mode at the time of startup. The control means includes temperature detection means for the compressor, the outdoor heat exchanger, and the indoor heat exchanger, and the temperature of the compressor is higher than the temperatures of the outdoor heat exchanger and the indoor heat exchanger. Stores the refrigerating machine oil discharge prevention operation mode when lower than a predetermined value, conversely stores the high efficiency operation mode when the temperature of the compressor becomes higher than a predetermined value, and stores the operation at startup The air conditioner according to claim 1, wherein a mode is indicated. The air conditioner according to claim 1, wherein the control means instructs the refrigeration oil discharge prevention operation mode during a defrosting operation. The control means includes temperature detection means for the discharge pipe or suction pipe of the compressor, the outdoor heat exchanger, and the indoor heat exchanger, and the temperature of the compressor discharge pipe or suction pipe is determined by the outdoor heat exchanger. Alternatively, when the temperature becomes lower than a predetermined temperature determined from the temperature of the indoor heat exchanger, the refrigerating machine oil discharge prevention operation mode is instructed.