JP2011252639A - Air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air conditioner with less generation of refrigerant noise that occurs as a switching takes place in a four-way valve when a heating operation starts up after a defrosting operation.SOLUTION: The air conditioner includes: a refrigerant circuit constituted by connecting, in a circular, a rotation speed variable compressor 1, a four-way valve 2, an outdoor heat exchanger 5, a pressure reducing expansion valve 11, and indoor heat exchanger 3; and a first defrost sensor 14 for detecting temperatures of the outdoor heat exchanger 5. The air conditioner is configured to: operate the compressor 1 from the start of a defrosting operation at a rotation speed of the maximum current value that the compressor 1 can be operated; control, when a temperature of the first defrosting sensor 14 reaches a first predetermined value lower than the defrost completion temperature, the compressor 1 to operate at a rotation speed of a certain predetermined operation current value which is lower than the maximum current value; and, control, when a temperature of the first defrosting sensor 14 reaches the defrost completion temperature, the compressor 1 to operate at the minimum rotation speed that the compressor 1 can be operated. This configuration prevents the pressure differential between a discharging and a sucking at the completion of defrosting, and reduces the generation of refrigerant noise which occurs as a switching takes place in the four-way valve 2.

Description

  The present invention relates to an air conditioner that reduces noise generated when a four-way valve is switched at the start of heating operation after defrosting.

  Conventionally, the current value of the compressor at the end of the defrosting operation is detected in order to reduce the noise generated when switching the four-way valve at the start of heating operation after the defrosting operation of this type of air conditioner. And according to this electric current value, the time until a four-way valve is switched to heating is changed, and the heating stop time is shortened (for example, refer to Patent Document 1).

Japanese Unexamined Patent Publication No. 07-174440

  However, in the configuration of the conventional air conditioner described above, the defrosting operation that causes the defrosting operation to continue even though the defrosting has been completed is generated and the high pressure is increased. Since the time from the start of operation to the switching of the four-way valve 2 at the start of heating operation is lengthened to reduce the high-low pressure difference to reduce noise, the higher the high pressure, the longer it takes to resume the heating operation. In addition, there is a problem that the heating pause time increases and the comfort of the user is greatly impaired due to a decrease in the room temperature.

  The present invention solves the above-mentioned conventional problems, and by suppressing the increase in high pressure at the end of the defrosting operation, noise at the time of switching the four-way valve is reduced, and comfort is improved by shortening the heating pause time. An object is to provide an air conditioner.

  In order to solve the above-described conventional problems, an air conditioner of the present invention includes a compressor with a variable rotation speed, a four-way valve that switches a refrigerant flow path, an outdoor heat exchanger that exchanges heat between the refrigerant and air, and a pressure reduction of the refrigerant. A defrosting operation, comprising a decompression expansion valve, a refrigerant circuit configured by annularly connecting indoor heat exchangers that exchange heat between indoor air and refrigerant, and a defrost sensor that detects the temperature of the outdoor heat exchanger When the compressor is operated at a rotational speed that is the maximum current value at which the compressor can be operated from the start, and the temperature of the defrost sensor reaches a first predetermined value lower than the defrost completion temperature, the compressor is By controlling the number of revolutions to a lower predetermined constant operating current value, when the temperature of the defrost sensor reaches the temperature of defrosting completion, by controlling the number of revolutions that can operate the compressor, The pressure difference between discharge and suction approaches to approach the end of defrosting From the start of the defrosting to the lowest speed at which the compressor can be operated, so that the pressure difference between the discharge and the suction at the end of the defrosting can be prevented from increasing suddenly. It is possible to reduce the generation of refrigerant noise that occurs when the four-way valve is switched.

  INDUSTRIAL APPLICABILITY The present invention can provide an air conditioner that suppresses a high pressure increase at the end of the defrosting operation, reduces noise when switching the four-way valve, and improves comfort by shortening the heating pause time.

The block diagram of the air conditioner in Embodiment 1 of this invention Control flow chart of the air conditioner The graph which shows the time change of the operating state at the time of defrosting operation of the air conditioner The graph which shows the time change of the operation state at the time of defrosting operation of the conventional air conditioner

  The first invention is a compressor with variable rotation speed, a four-way valve for switching a refrigerant flow path, an outdoor heat exchanger for exchanging heat between the refrigerant and air, a decompression expansion valve for depressurizing the refrigerant, and exchanging heat between the indoor air and the refrigerant. A refrigerant circuit configured by annularly connecting indoor heat exchangers, and a defrost sensor that detects the temperature of the outdoor heat exchanger, and is capable of operating the compressor from the start of the defrost operation. When the motor is operated at a rotational speed that is a current value and the temperature of the defrost sensor reaches a first predetermined value that is lower than the defrost completion temperature, the compressor is rotated at a predetermined constant operating current value that is lower than the maximum current. When the temperature of the defrost sensor reaches the temperature at which the defrost is completed, the pressure difference between the discharge and the suction becomes close to the end of the defrost by controlling the compressor to the lowest rotation speed at which the compressor can be operated. The compressor can be operated from the time it is going to grow until the end of defrosting Since the engine speed is reduced to the lowest speed, the pressure difference between discharge and suction at the end of defrosting can be prevented from suddenly increasing, and the generation of refrigerant noise that occurs when switching the four-way valve when resuming heating can be reduced. Can do.

  In particular, in the air conditioner of the first invention, the second invention is the operation current value when the temperature of the defrost sensor reaches a first predetermined value lower than the defrost completion temperature according to the outside air temperature. If the defrosting is performed at a high current value when the outside air temperature is low, and a low current value when the outside air temperature is high, the pressure difference between the discharge and the suction becomes large when the outside air temperature is high. Can be suppressed.

  The third invention, in particular, in the first or second invention, switches the four-way valve to the heating operation side after the difference between the high pressure and the low pressure falls below the second predetermined value, and stops the compressor. The four-way valve can be switched without causing the noise to be kept at a constant level, and the comfort can be improved by shortening the time until the heating operation is resumed.

  In the fourth aspect of the invention, in particular, in the third aspect of the invention, the difference between the high pressure and the low pressure is determined based on the current value of the compressor. Even in an air conditioner not equipped with a pressure detector, the four-way valve is switched. The noise can be kept at a constant level.

  In particular, the fifth aspect of the invention provides a controller for selecting a first predetermined value, which is the difference between the high pressure and the low pressure when the four-way valve is switched, in the third or fourth invention. In conditions where the problem does not become a problem, the first predetermined value can be set higher than the initial value and the four-way valve can be switched to shorten the time until the heating is restarted. By setting the value lower than the value, it is possible to select the operation so as to reduce the noise at the time of switching the four-way valve.

  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 is a configuration diagram of an air conditioner according to the first embodiment of the present invention, FIG. 2 is a control flowchart of the air conditioner, and FIG. 3 is a compressor rotation during a defrosting operation of the air conditioner. FIG. 4 is a graph showing the change over time of the number, the discharge pressure, the suction pressure, and the pressure difference between the discharge and the suction, and FIG. 4 shows the compressor rotation speed, discharge pressure, suction pressure, It is a graph which shows the time change of a pressure difference.

In FIG. 1, a variable frequency type compressor 1 is provided, and the capacity is controlled by changing the rotational speed of the compressor 1 by changing the power supply frequency. The refrigerant discharged from the compressor 1 passes through the four-way valve 2 and is liquefied and condensed by the indoor heat exchanger 3 during heating, is decompressed and expanded by the decompression expansion valve 11, absorbs heat by the outdoor heat exchanger 5, and is removed. At the time of frosting, it is liquefied and condensed by the outdoor heat exchanger 5 and defrosted, decompressed and expanded by the decompression expansion valve 11, absorbed by the indoor heat exchanger 3, and sucked into the compressor 1 through the four-way valve 2.

  Moreover, the 1st defrost sensor 14 which detects frost formation from the temperature of the outdoor heat exchanger 5, The 2nd defrost sensor 17 which detects the defrost degree from the exit temperature of the outdoor heat exchanger 5 at the time of defrost, The outside air temperature sensor 12 that detects the outside air temperature and the control device 15 also detect the current value of the compressor 1.

  The air conditioner controller 16 also has a function of selecting a first predetermined value when the four-way valve 2 is switched.

  About the air conditioner in this Embodiment comprised as mentioned above, the graph which shows the time change of the flowchart of FIG. 2 and the compressor rotation speed of FIG. 3 and FIG. 4, discharge pressure, suction pressure, and a pressure difference is used. The operation and action will be described below.

  First, during the heating operation, when the detection value of the first defrosting sensor 14 satisfies the defrosting operation start condition, the rotation speed of the compressor 1 is set to a predetermined low speed constant rotation speed, and then the four-way valve 2 is defrosted. And the compressor 1 is operated at a rotational speed that provides the maximum current value that can be operated.

  Then, after the second defrost sensor 17 reaches the first predetermined value lower than the defrost completion temperature, the rotation speed of the compressor 1 is set to a predetermined constant compressor current according to the detected value of the outside air temperature sensor 12. Drive with value.

  After that, after the second defrost sensor 17 reaches a predetermined value for completion of defrosting, the compressor 1 is operated at the lowest speed at which the compressor 1 can be operated, and the current of the compressor 1 detected by the control device 15 is detected. When the difference between the high pressure and the low pressure becomes a value equal to or less than a second predetermined value that is a predetermined value, the four-way valve 2 is switched to the heating side and the heating operation is resumed.

  As shown in FIG. 3, in the operation state during the defrosting operation, the rotational speed is controlled so that the maximum compressor current value is obtained until the end of the defrosting control. Immediately after the start of defrosting, the pressure difference is small, so the rotational speed of the compressor rises and promotes quick defrosting. As the defrosting progresses, the suction pressure increases and the discharge pressure tends to increase, but when the second defrosting sensor 17 reaches the first predetermined value close to the end of the defrosting, the rotational speed of the compressor 1 is decreased. The compressor is operated so that the current of the compressor becomes a constant current lower than the maximum current.

  And by the detection of the 2nd defrost sensor 17, at the time of completion | finish of defrost, rotation of a compressor is reduced to the minimum rotation speed, and the pressure difference is suppressed.

  Here, for comparison between the conventional example and the present invention, FIG. 4 shows a defrosting operation state of a conventional air conditioner. In order to perform defrosting with constant compressor rotation, both the discharge and suction pressures are low at the start of the defrosting operation, but both the discharge and suction pressures rise as defrosting progresses, and then increase rapidly just before the end of the defrosting To do. For this reason, the pressure difference also increases rapidly.

  As described above, in this embodiment, the compressor 1 is operated at the maximum rotational speed at which the compressor 1 can be operated from the start of defrosting, and the rotational speed of the compressor 1 is decreased immediately before completion of the defrosting. At the end of the frost, the four-way valve 2 is switched at a constant high and low pressure difference after the minimum rotation speed, so the increase in the high pressure due to the color defrosting from the end of the defrosting to the switching of the four-way valve 2 is suppressed. In addition to reducing the time, the noise during switching can always be kept below a predetermined level.

  In the present embodiment, the controller 16 can set a first predetermined value that is a pressure difference when the four-way valve 2 is switched, and the first predetermined value is set high in an operating condition in which the noise level is not a problem. The time from the end of defrosting to the switching of the four-way valve 2 can be shortened. On the other hand, the first predetermined value is set low when the noise is a concern, and the four-way valve 2 is switched under a small pressure difference. The noise can be further reduced.

  As described above, the air conditioner according to the present invention can suppress noise generated when the four-way valve is switched, and can be applied to applications such as a vending machine using the four-way valve.

DESCRIPTION OF SYMBOLS 1 Compressor 2 Four-way valve 3 Indoor heat exchanger 5 Outdoor heat exchanger 11 Pressure-reduction expansion valve 12 Outside temperature sensor 14 1st defrost sensor 15 Control apparatus 16 Controller 17 2nd defrost sensor

Claims (5)

A compressor with variable speed, a four-way valve for switching the refrigerant flow path, an outdoor heat exchanger for exchanging heat between the refrigerant and air, a decompression expansion valve for depressurizing the refrigerant, and an indoor heat exchanger for exchanging heat between the indoor air and the refrigerant The number of revolutions is a maximum current value at which the compressor can be operated from the start of the defrosting operation, including a refrigerant circuit configured in a ring shape and a defrosting sensor that detects the temperature of the outdoor heat exchanger. When the temperature of the defrost sensor reaches a first predetermined value lower than the defrost completion temperature, the compressor is controlled to a rotation speed that becomes a predetermined constant operating current value lower than the maximum current, When the temperature of a defrost sensor reaches the temperature of defrost completion, the air conditioner characterized by controlling to the minimum rotation speed which can drive | operate the said compressor. The air conditioner according to claim 1, wherein a predetermined constant operating current value when the temperature of the defrost sensor reaches a first predetermined value lower than the defrost completion temperature is changed according to the outside air temperature. The air conditioner according to claim 1 or 2, wherein the four-way valve is switched to the heating operation side after a difference between the high pressure and the low pressure is equal to or less than a second predetermined value. The air conditioner according to claim 3, wherein a difference between the high pressure and the low pressure is determined based on a current value of the compressor. The air conditioner according to claim 3 or 4, further comprising a controller for selecting a first predetermined value that is a difference between a high pressure and a low pressure when the four-way valve is switched.