JP2009085463A - Air conditioner - Google Patents

Abstract

In an air conditioner having a heating means (electric heater) in a compressor, the power supply to the heater is optimized to reduce power consumption, and the reliability at the start of the compressor is improved.
A refrigeration cycle including at least a compressor, a condenser (indoor heat exchanger during heating operation) and an evaporator (outdoor heat exchanger during heating operation), and electricity for heating the compressor. The air conditioner having a typical heating means 20 and a control means 30 for controlling the heating means 20 comprises a compressor temperature detecting means 31 for detecting the temperature of the compressor 11, and the control means 30 includes the air When the compressor temperature detected by the compressor temperature detecting means 31 is lowered to a predetermined temperature Ta after the operation of the conditioner is stopped, the heating means 20 is operated to heat the compressor 11, and the compressor temperature is heated after the heating. When the temperature reaches a predetermined temperature Tb (Tb> Ta), the operation of the heating means 20 is stopped.
[Selection] Figure 1

Description

  The present invention relates to an air conditioner provided with a heating means in a compressor, and more particularly to a control technique for the heating means.

  When the operation of the air conditioner (air conditioner) stops, the refrigerant stays in the compressor, condenses and dissolves in the refrigeration oil, and the concentration of the refrigeration oil decreases. This phenomenon is particularly common at low outside temperatures, and causes poor lubrication at the start of operation after a long stop.

  Therefore, an electric heater such as a crankcase heater is provided in the compressor to heat the compressor, but the power consumption becomes a problem.

  In order to solve this problem, in the invention described in Patent Literature 1, when the compressor is stopped, the temperature detected by the thermistor provided in the lower part of the compressor and the temperature detected by the thermistor provided in the condenser (indoor heat exchanger) are used. When the temperature difference from the temperature is, for example, 5 ° C. or more, the heater is energized.

  In the invention described in Patent Document 2, when the compressor is stopped, the heater is energized by any combination of the discharge temperature of the compressor, the outside air temperature, the temperature of the indoor heat exchanger, and the temperature of the outdoor heat exchanger. By controlling this, standby power is reduced.

JP 61-213555 A JP 2002-267280 A

  However, in the case of the above-described prior art, since the heater is energized when predetermined conditions are satisfied, heat is supplied by the heater even in a state where the compressor after operation stops has a quantity of heat that does not cause the refrigerant to melt. There can be cases.

  In addition, since the temperature at several locations is used as a control factor, it is difficult to respond to sudden changes in ambient temperature, which may impair the reliability of the compressor or deteriorate startup characteristics (slow start). ).

  Accordingly, an object of the present invention is to optimize the power supply to the heater in an air conditioner having a heating means (crank heater, winding heating, etc.) in the compressor and reduce the power consumption. It is to improve the reliability at the time of starting.

  In order to solve the above problems, the invention described in claim 1 controls a refrigeration cycle including at least a compressor, a condenser and an evaporator, an electric heating means for heating the compressor, and the heating means. An air conditioner comprising control means, comprising compressor temperature detection means for detecting the temperature of the compressor, wherein the control means is detected by the compressor temperature detection means after the operation of the air conditioner is stopped. When the compressor temperature is lowered to a predetermined temperature Ta, the heating means is operated to heat the compressor, and after the heating, the compressor temperature reaches a predetermined temperature Tb (Tb> Ta) Then, the operation of the heating means is stopped.

  The invention according to claim 2 further includes an outside air temperature detecting means for detecting an outside air temperature, and the control means compresses the compression when the outside air temperature detected by the outside air temperature detecting means is lower than a predetermined temperature. The heating means is controlled based on the machine temperature, and when the outside air temperature is higher than the predetermined temperature, the heating means is controlled in consideration of control factors other than the compressor temperature.

  The invention described in claim 3 is characterized in that the compressor temperature detecting means is provided on the side of the compressor oil reservoir of the compressor.

  According to the first aspect of the present invention, since the control factor for operating the electric heating means (heater) is only the temperature of the compressor, the heater is energized only when the heating is actually required. Well, for example, when there is a heat quantity that does not cause the refrigerant to melt in the compressor after the operation is stopped, the heater is not energized, and the power consumption is reduced accordingly.

  According to the second aspect of the present invention, it is further provided with an outside air temperature detecting means for detecting the outside air temperature, and the control means is a case where the outside air temperature detected by the outside air temperature detecting means is a predetermined low outside air temperature. In addition, the heating means is controlled based on the compressor temperature, and when the outside air temperature is not the low outside air temperature, the heating means is controlled in consideration of a control factor other than the compressor temperature. In addition to the effect of 1, the reliability at the time of starting of a compressor can be improved.

  According to the invention described in claim 3, since the compressor temperature detecting means is provided on the compressor oil storage portion side of the compressor, the condition (temperature) of the refrigerant in the refrigerator oil is properly determined. be able to.

Next, an embodiment of the present invention will be described with reference to FIGS. 1 to 4, but the present invention is not limited to this. FIG. 1 is a schematic cross-sectional view showing a refrigeration cycle provided in the air conditioner of the present invention, FIG. 2 is a schematic diagram illustrating the internal structure of the compressor in the present invention, and FIG. 3 is for explaining the operation of the heating means in the present invention. A timing chart and FIG. 4 are graphs showing a startup pattern of the compressor.

  The air conditioner according to this embodiment includes a refrigeration cycle 10 shown in FIG. The refrigeration cycle 10 includes a compressor 11, an four-way valve 12, an outdoor heat exchanger 13 having an outdoor fan 13a, an expansion valve 14, an indoor heat exchanger 15 having an indoor fan 15a, and an accumulator 16.

  As shown in FIG. 2, the compressor 11 has a cylindrical sealed container 11 a, in which the compression unit 110 and an electric motor 120 that drives the compression unit 110 are housed. The lower part is a refrigerating machine oil reservoir 130.

  A refrigerant discharge pipe 111 from which high-temperature and high-pressure gas refrigerant is discharged and a refrigerant suction pipe 112 from which the refrigerant is returned from the accumulator 16 are connected to the compression unit 110. The hermetic container 11 a is provided with a heater 20 as a heating means for heating the compressor 11.

  For example, a heater called a crankcase heater may be used as the heater 20, but a motor winding heating method in which the motor winding of the electric motor 120 is energized and heated may be employed. The compressor 11 may be either a rotary compressor or a scroll compressor, and can be used regardless of whether it is a constant speed compressor or a variable speed compressor using an inverter.

  During the cooling operation, the four-way valve 12 is switched to the state shown in the figure, and the high-temperature and high-pressure refrigerant gas generated by the compressor 11 flows into the outdoor heat exchanger 13 through the four-way valve 12 and is then sent to the outdoor blower 13a. It is condensed and liquefied by dissipating heat to the blown outside air.

  This liquid refrigerant is adiabatically expanded by the expansion valve 14 to form a gas-liquid two-phase flow, flows into the indoor heat exchanger 15, cools the indoor air blown by the indoor blower 15a, and evaporates and evaporates. The air is sucked into the compressor 11 through the valve 12 and the accumulator 16.

  During the heating operation, the four-way valve 12 is switched to the state shown in the chain line, and the high-temperature and high-pressure refrigerant gas generated by the compressor 11 is opposite to that during the cooling operation, the indoor heat exchanger 15 → the expansion valve 14 → It flows from the outdoor exchanger 13 → the four-way valve 12 → the accumulator 16 → the compressor 11.

  Thus, during the cooling operation, the outdoor heat exchanger 13 acts as a condenser, and the indoor heat exchanger 15 acts as an evaporator. On the other hand, during the heating operation, the outdoor heat exchanger 13 acts as an evaporator, and the indoor heat exchanger 15 acts as a condenser.

  When the operation of the air conditioner is stopped, in order to prevent the refrigerant from staying and condensing in the compressor 11 and condensing into the refrigerating machine oil, the heater 20 is energized to heat the refrigerating machine oil, and the temperature is equal to or higher than the saturation temperature of the refrigerant. Let the temperature rise.

  The energization of the heater 20 is controlled by the control means 30 shown in FIG. 1, but in the present invention, the temperature of the compressor 11 is detected in order to optimize the energization of the heater 20 and reduce the power consumption. Compressor temperature detecting means 31 is provided. For example, a microcomputer may be used as the control unit 30, and a thermistor may be used as the compressor temperature detection unit 31, for example.

  In this embodiment, as shown in FIG. 2, the compressor temperature detecting means 31 is preferably provided on the bottom side of the compressor 11, that is, on the side of the refrigerating machine oil storage unit 130, and the refrigerating machine oil in the compressor 11 substantially. Detect temperature.

  The control means 30 is provided in the power supply line of the heater 20 only when the temperature detection signal from the compressor temperature detection means 31 is received and the compressor temperature (refrigeration oil temperature) actually drops below a specified value. The switch 20a is turned on to supply power to the heater 20 to heat the compressor 11.

  This is a basic control mode of the heater 20 in the present invention. In this embodiment, the outside air temperature is used as a control factor in addition to the compressor temperature. The outside air temperature may be obtained by, for example, the outside air temperature detection means 32 provided on the windward side of the outdoor heat exchanger 13.

  The control unit 30 determines whether or not the outside air temperature is a low outside air temperature of, for example, 0 ° C. or less. If the outside air temperature is the low outside air temperature, the controller 30 supplies the heater 20 based on the temperature detection signal from the compressor temperature detecting unit 31. Control energization.

  An example of this will be described with reference to FIG. In this example, the compressor temperature Ta at which power supply to the heater 20 is started is 0 ° C., and the compressor temperature Tb at which power supply to the heater 20 is stopped is 7 ° C.

  FIG. 3A shows the case where the outside air temperature is −5 ° C. When the compressor temperature is reduced to 0 ° C. after the operation of the air conditioner is stopped, the switch 20a is turned on to supply power to the heater 20. And the compressor 11 is heated. By this heating, when the compressor temperature rises and reaches 7 ° C., the switch 20a is turned off and power supply to the heater 20 is stopped.

  FIG. 3B shows the case where the outside air temperature is −20 ° C. Also in this case, after the operation of the air conditioner is stopped, when the compressor temperature decreases to 0 ° C., the switch 20a is turned on to start the power supply to the heater 20 to heat the compressor 11, but the outside air Since the compressor temperature does not easily rise to 7 ° C. due to the considerably low temperature, the heater 20 is supplied with power for a long time.

  Further, when the compressor 11 is started at a low outside air temperature (for example, 0 ° C. or lower), the rotation speed of the compressor 11 is set to be as shown in the start pattern shown in FIG. It is preferable to raise it slowly and stepwise.

  On the other hand, when the outside air temperature is high (for example, when it exceeds 0 ° C.), the heater 20 is energized based on the outside air temperature and / or the outdoor heat exchanger temperature (condenser temperature), for example. Control. In starting the compressor 11, since the outside air temperature is high, the rotation speed of the compressor 11 can be increased stepwise in the shortest time as shown in the start pattern shown in FIG. 4B.

The schematic diagram which shows the refrigerating cycle with which the air conditioner of this invention is provided. The typical sectional view illustrating the internal structure of the compressor in the present invention. The timing chart for operation | movement description of the heating means in this invention. The graph which shows the starting pattern of a compressor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Refrigeration cycle 11 Compressor 110 Compression part 120 Electric motor 130 Refrigerator oil storage part 12 Four-way valve 13 Outdoor heat exchanger 14 Expansion valve 15 Indoor heat exchanger 16 Accumulator 20 Heater (compressor heating means)
30 Control means 31 Compressor temperature detection means 32 Outside air temperature detection means

Claims (3)

In an air conditioner comprising a refrigeration cycle including at least a compressor, a condenser and an evaporator, an electric heating means for heating the compressor, and a control means for controlling the heating means,
Compressor temperature detecting means for detecting the temperature of the compressor, and the control means, after the operation of the air conditioner is stopped, until the compressor temperature detected by the compressor temperature detecting means reaches a predetermined temperature Ta. When the temperature drops, the heating means is operated to heat the compressor, and the operation of the heating means is stopped when the compressor temperature reaches a predetermined temperature Tb (Tb> Ta) after heating. Air conditioner.   Outside temperature detection means for detecting outside temperature is further provided, and the control means controls the heating means based on the compressor temperature when the outside air temperature detected by the outside air temperature detection means is lower than a predetermined temperature. 2. The air conditioner according to claim 1, wherein when the outside air temperature is higher than the predetermined temperature, the heating unit is controlled in consideration of a control factor other than the compressor temperature.   The air conditioner according to claim 1 or 2, wherein the compressor temperature detecting means is provided on a refrigerator oil storage side of the compressor.

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