JP2007292439A - Outdoor unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an outdoor unit for an air conditioner capable of suppressing the blowing noise of a fan without degrading operation efficiency. <P>SOLUTION: The outdoor unit 3 comprises an outdoor heat exchanger 13, an outdoor fan 29 and a control section 4. The outdoor heat exchanger 13 works as an evaporator in heating operation and exchanges heat with air. The outdoor fan 29 produces air flow passing the surface of the outdoor heat exchanger 13. The control section 4 performs fan control in frost to reduce the rotating speed of the outdoor fan 29 when frosting to the outdoor heat exchanger 13 is detected or considered. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an outdoor unit of an air conditioner that includes an outdoor fan that accelerates heat exchange by applying air to an outdoor heat exchanger and controls the number of rotations of the outdoor fan when the outdoor heat exchanger is frosted.

An outdoor heat exchanger and an outdoor fan that generates an air flow are arranged inside the outdoor unit of the air conditioner. During the heating operation, the outdoor heat exchanger becomes an evaporator, and frost begins to cover the surface of the outdoor heat exchanger as the operation time elapses. If the frosting further proceeds, it becomes a draft resistance and there is a high possibility that the performance will be lowered. In order to prevent this degradation in performance, control for maintaining the rotation speed constant by increasing the input to the motor rotating the outdoor fan or increasing the rotation speed is widely adopted (for example, Patent Documents). 1).
JP 2004-218936 A

  However, if the outdoor fan is maintained at the same rotation speed while the ventilation resistance is large, the blowing sound of the outdoor fan increases, which may cause discomfort to the user. Further, if the defrosting (defrosting) operation is performed earlier, an increase in the blowing sound can be solved, but it is not preferable because the operation efficiency is lowered.

  The subject of this invention is providing the outdoor unit of the air conditioning apparatus which can suppress the ventilation sound of a fan, without reducing operating efficiency.

  An outdoor unit according to a first aspect of the present invention is an outdoor unit of an air conditioner to which an indoor unit is connected, and includes an outdoor heat exchanger, an outdoor fan, and a control unit. The outdoor heat exchanger exchanges heat with air as an evaporator during heating operation. The outdoor fan generates an air flow that passes through the surface of the outdoor heat exchanger. When the frost formation on the outdoor heat exchanger is detected or estimated, the controller performs frost fan control for reducing the rotational speed of the outdoor fan.

  In this outdoor unit, even if the ventilation resistance increases due to frost formation, the increase amount of the blowing sound is small. For this reason, unpleasant noise is suppressed.

  The outdoor unit according to the second aspect of the present invention is the outdoor unit according to the first aspect of the present invention, and the frosting fan control is not executed until a predetermined time has elapsed from the start of the heating operation.

  Here, since the heating operation is maintained for a predetermined time, even when the operation is started with low outside air, warm air can be provided.

  An outdoor unit according to a third aspect of the present invention is the outdoor unit according to the first aspect of the present invention, and the fan control at the time of frost formation includes lowering a preset target rotational speed of the outdoor fan.

  Here, at the time of frost formation, the rotational speed of the outdoor fan decreases, and the increase amount of the blowing sound becomes small. For this reason, noise is reduced.

  An outdoor unit according to a fourth aspect of the present invention is the outdoor unit according to the first aspect of the present invention, and the frosting fan control includes lowering the upper limit of the input value supplied to the outdoor fan.

  Here, at the time of frost formation, the rotational speed of the outdoor fan decreases, and the increase amount of the blowing sound becomes small. For this reason, noise is reduced.

  An outdoor unit according to a fifth aspect of the present invention is the outdoor unit according to the first aspect of the present invention, wherein when a predetermined time has elapsed from the start of the heating operation and the evaporating temperature of the outdoor heat exchanger is lower than the predetermined temperature, a frosting fan Control is executed.

  Here, frost formation is detected without using a special device, and blowing noise is suppressed.

  An outdoor unit according to a sixth aspect of the present invention is the outdoor unit according to the first aspect of the present invention, wherein the frosting fan control is executed when a predetermined time has elapsed from the start of the heating operation and the outside air temperature falls below the predetermined temperature. .

  Here, frost formation is detected without using a special device, and blowing noise is suppressed.

  The outdoor unit according to the seventh aspect of the present invention is the outdoor unit according to the first aspect of the present invention, and when the predetermined time has elapsed from the start of the heating operation and the low pressure side falls below the predetermined pressure, the frosting fan control is executed.

  Here, frost formation is detected without using a special device, and blowing noise is suppressed.

  An outdoor unit according to an eighth aspect of the present invention is the outdoor unit according to the first aspect of the present invention, wherein a predetermined time has elapsed from the start of the heating operation, and an on-time ratio in one cycle of the drive voltage supplied to the outdoor fan is preset. When the on-time ratio is exceeded, fan control during frost formation is executed.

  Here, frost formation is detected without using a special device, and blowing noise is suppressed.

  An outdoor unit according to a ninth aspect of the present invention is the outdoor unit according to the first aspect of the present invention, wherein a predetermined time has elapsed since the start of heating operation, and the rotational speed of the outdoor fan falls below a preset target rotational speed. Fan control during frost formation is executed.

  Here, frost formation is detected without using a special device, and blowing noise is suppressed.

  An outdoor unit according to a tenth aspect of the present invention is the outdoor unit according to the first aspect of the present invention, wherein an average value of inputs supplied to the outdoor fan is calculated before frosting fan control is started, While the fan control is being executed, the average value of the input calculated previously is supplied to the outdoor fan.

  Here, the rotational speed of the outdoor fan is automatically reduced by the ventilation resistance due to frost formation. For this reason, the increase amount of blowing sound becomes small.

  An outdoor unit according to an eleventh aspect of the present invention is the outdoor unit according to the first aspect of the present invention, wherein when the frosting fan control is performed, the rotational speed of the outdoor fan falls below a preset lower limit rotational speed. If so, start defrosting operation.

  In this outdoor unit, since the heating capacity is reduced by the fan control at the time of frost formation, the number of rotations of the outdoor fan is monitored to prevent the heating capacity from falling beyond an allowable range. For this reason, if frosting progresses to such an extent that the increase in blowing noise cannot be suppressed, the defrosting operation is started in a timely manner, so that the heating performance is restored before the user feels that heating is insufficient.

  An outdoor unit according to a twelfth aspect of the present invention is the outdoor unit according to the first aspect of the present invention, wherein when the fan control during frost formation is performed, the rotation speed of the outdoor fan and the rotation speed of the outdoor fan before frost formation are When the difference exceeds a preset allowable value, the defrosting operation is started.

  In this outdoor unit, the heating capacity decreases due to fan control during frost formation, so the difference between the rotation speed of the outdoor fan and the rotation speed of the outdoor fan before frost formation is monitored, and the heating capacity exceeds the allowable range. Prevents the decline. For this reason, since the defrosting operation is started in a timely manner when the frosting progresses to such an extent that the increase of the blowing sound cannot be suppressed, the heating performance is recovered before the user feels that the heating is insufficient.

  An outdoor unit according to a thirteenth aspect of the present invention is the outdoor unit according to the first aspect of the present invention, wherein when the frosting fan control is performed, the rotation number of the outdoor fan and the rotation number of the outdoor fan before frosting are When the integrated value of the difference exceeds the preset allowable integrated value, the defrosting operation is started.

  In this outdoor unit, the heating capacity decreases due to fan control during frost formation, so the integrated value of the difference between the rotation speed of the outdoor fan before frost formation and the current rotation speed is monitored, and the heating capacity falls within the allowable range. It is prevented from falling over. For this reason, since the defrosting operation is started in a timely manner when the frosting progresses to such an extent that the increase of the blowing sound cannot be suppressed, the heating performance is recovered before the user feels that the heating is insufficient. Moreover, since the start of the defrosting operation is determined based on the integrated value of the rotational speed difference, even if a sudden back wind acts on the outdoor fan and the rotational speed decreases suddenly, or the power supply voltage decreases and the outdoor fan Even when the number of revolutions suddenly decreases, the defrosting operation is not erroneously started.

  In the outdoor unit according to the first aspect of the present invention, even if the ventilation resistance increases due to frost formation, the increase amount of the blowing sound is small. For this reason, unpleasant noise is suppressed.

  In the outdoor unit according to the second aspect of the invention, the heating operation is maintained for a predetermined time, so that warm air can be provided even when the operation is started with low outside air.

  In the outdoor units according to the third and fourth aspects of the invention, the rotational speed of the outdoor fan decreases during frost formation, and the amount of increase in the blowing noise decreases. For this reason, noise is suppressed.

  In the outdoor units according to the fifth to ninth aspects, frost formation is detected without using a special device, and the blowing sound is suppressed.

  In the outdoor unit according to the tenth aspect of the present invention, the rotational speed of the outdoor fan automatically decreases due to ventilation resistance caused by frost formation. For this reason, the increase amount of blowing sound is small.

  Since the outdoor unit according to the eleventh to thirteenth inventions starts defrosting operation in a timely manner when frosting progresses to such an extent that the increase in blowing sound cannot be suppressed, the heating performance is improved before the user feels that the heating is insufficient. Recover.

<Configuration of air conditioner>
The refrigerant circuit of the air conditioning apparatus containing the outdoor unit which concerns on one Embodiment of this invention is shown in FIG. The air conditioner 1 is a multi-room type air conditioner, and has a configuration in which a plurality of indoor units 3 are connected in parallel to one outdoor unit 2. The refrigerant circuit 10 of the air conditioner 1 is mainly composed of a compressor 11, a four-way switching valve 12, an outdoor heat exchanger 13, an expansion valve 14, and an indoor heat exchanger 16, which are connected in order. It is a cycle. Here, the compressor 11 is a variable capacity inverter compressor that performs rotational speed control by an inverter. An accumulator 20 that separates liquid refrigerant and gas refrigerant is provided on the suction pipe side of the compressor 11.

  The compressor 11, the four-way switching valve 12, the outdoor heat exchanger 13 and the expansion valve 14 are included in the outdoor unit 2, and the indoor heat exchanger 16 is included in the indoor unit 3. The four-way switching valve 12 and the indoor heat exchanger 16 are connected by a refrigerant communication pipe 17a, and the expansion valve 14 and the indoor heat exchanger 16 are connected by a refrigerant communication pipe 17b. The refrigerant communication pipes 17 a and 17 b are arranged between the outdoor unit 2 and the indoor unit 3. The internal refrigerant circuit of the outdoor unit 2 is provided with a gas side closing valve 18 and a liquid side closing valve 19. The gas side closing valve 18 is arranged on the four-way switching valve 12 side, and the liquid side closing valve 19 is arranged on the expansion valve 14 side. A refrigerant communication pipe 17 a is connected to the gas side shut-off valve 18, and a refrigerant communication pipe 17 b is connected to the liquid side shut-off valve 19. These closing valves 18 and 19 are closed when the outdoor unit 2 and the indoor unit 3 are installed. Then, the closing valves 18 and 19 are opened after the outdoor unit 2 and the indoor unit 3 are installed on the site and the refrigerant communication pipe 17a and the refrigerant communication pipe 17b are connected to the closing valves 18 and 19, respectively.

  The outdoor unit 2 is provided with an outdoor fan 29 that generates an air flow in order to promote heat exchange between the air and the outdoor heat exchanger 13.

  Moreover, the air conditioning apparatus 1 including the outdoor unit 2 of this embodiment is provided with many temperature sensors consisting of thermistors. The outdoor temperature sensor 102 detects the ambient temperature where the outdoor unit 2 is installed, and the discharge pipe temperature sensor 111 is attached to the discharge pipe of the compressor 11 and detects the discharge pipe temperature To. The evaporation temperature sensor 113 during the heating operation is attached to the outdoor heat exchanger 13 to detect the evaporation temperature Te, and the liquid pipe temperature sensor 117 is attached to the outlet side during the heating operation of the indoor heat exchanger 16, The tube temperature Tl is detected.

  Further, a low pressure side pressure sensor 213 for detecting a low pressure side pressure is provided between the four-way switching valve 12 and the outdoor heat exchanger 13. Based on the detected values of these temperature sensors and the detected values of the pressure sensor, the control unit 4 controls the operation of the air conditioner 1.

<Operation of air conditioner>
(Cooling operation)
Next, the operation of the air conditioner 1 will be described. During the cooling operation, the four-way switching valve 12 is maintained in the state indicated by the solid line in FIG. The high-temperature and high-pressure gas refrigerant discharged from the compressor 11 flows into the outdoor heat exchanger 13 through the four-way switching valve 12, and exchanges heat with the outdoor air to condense and liquefy. The liquefied refrigerant is depressurized to a predetermined low pressure by the expansion valve 14 and further evaporated by exchanging heat with indoor air in the indoor heat exchanger 16. The indoor air cooled by the evaporation of the refrigerant is blown out into the room by an indoor fan (not shown) to cool the room. The refrigerant evaporated and vaporized in the indoor heat exchanger 16 returns to the outdoor unit 2 through the refrigerant communication pipe 17 a and is sucked into the compressor 11.

(Heating operation)
During the heating operation, the four-way switching valve 12 is maintained in a state indicated by a broken line in FIG. The high-temperature and high-pressure gas refrigerant discharged from the compressor 11 flows into the indoor heat exchanger 16 of each indoor unit 3 through the four-way switching valve 12, and exchanges heat with indoor air to condense and liquefy. The indoor air heated by the condensation of the refrigerant is blown out into the room by an indoor fan to heat the room. The refrigerant liquefied in the indoor heat exchanger 16 returns to the outdoor unit 2 through the refrigerant communication pipe 17b. The refrigerant that has returned to the outdoor unit 2 is decompressed to a predetermined low pressure by the expansion valve 14, and is further evaporated by exchanging heat with outdoor air in the outdoor heat exchanger 13. The refrigerant evaporated and evaporated in the outdoor heat exchanger 13 is sucked into the compressor 11 through the four-way switching valve 12.

<Outdoor fan for outdoor unit>
The outdoor fan 29 includes a motor 29a. The motor 29a is a long-life DC brushless motor, and the number of revolutions can be changed by controlling the ON time ratio (DUTY ratio) during one cycle of power input (DUTY control). The rotation speed is detected by a rotation speed sensor 129 formed by a Hall IC provided in the motor 29a.

  For example, when the ventilation resistance increases due to frost formation on the outdoor heat exchanger 13, the rotational speed of the outdoor fan 29 decreases. This decrease in the rotational speed is detected by the rotational speed sensor 129. Further, as the DUTY ratio is increased, the input supplied to the motor 29a of the outdoor fan 29 increases, so the rotational speed of the outdoor fan 29 increases.

  In the normal control, the input is increased / decreased in order to keep the rotation speed of the outdoor fan 29 constant, and the outdoor fan input is increased / decreased to maintain a constant rotation speed as the rotation speed increases / decreases. FIG. 3 is a graph showing the “relationship between outdoor fan input, outdoor fan rotation speed, and outdoor fan blowing sound when normal control is performed during frost formation”, and the horizontal axis represents the elapsed time after the start of heating operation. The vertical axis indicates the outdoor fan input, the outdoor fan rotation speed, and the outdoor fan blowing sound in order from the bottom. When the predetermined time TD has passed since the start of the heating operation, frosting of the outdoor heat exchanger 13 starts and the ventilation resistance starts to increase. In the case of normal control, the outdoor fan input is increased so as to keep the rotational speed of the outdoor fan 29 constant so that the rotational speed does not drop due to ventilation resistance. For this reason, ventilation sound increases rapidly.

<Fan control during frost formation>
FIG. 2 is a control block diagram of the air conditioner 1 including the outdoor unit 2 of the present embodiment. In FIG. 2, the control unit 4 receives detection values from the outdoor temperature sensor 102, the evaporation temperature sensor 113, the outdoor fan rotation speed sensor 129, and the low pressure side pressure sensor 213 by the frost detection unit 41, and the outdoor heat exchanger 13 frost formation is detected or estimated, and the outdoor fan 29 is controlled via the outdoor fan control unit 42.

  When the frosting of the outdoor heat exchanger 13 starts and the ventilation resistance starts to increase, the control unit 4 keeps the outdoor fan input constant and the outdoor fan rotation speed is set to prevent the outdoor fan 29 from increasing the blowing sound. I try to go down. This is fan control at the time of frost formation, and this suppresses the increase amount of blowing sound.

  FIG. 4 is a graph showing “relationship between outdoor fan input, outdoor fan rotation speed, and outdoor fan blowing sound when fan control is performed during frost formation”, and the horizontal axis represents the elapsed time after the start of heating operation. The vertical axis indicates the outdoor fan input, the outdoor fan rotation speed, and the outdoor fan blowing sound in order from the bottom. When the heating operation is started and the predetermined time TD is passed, frost formation of the outdoor heat exchanger 13 starts and the ventilation resistance starts to increase. However, since the outdoor fan input is kept constant, the rotational speed of the outdoor fan 29 naturally decreases due to the ventilation resistance, and the amount of increase in the blowing sound becomes smaller than when the normal control is maintained.

<Fan control logic during frosting>
FIG. 5 is a flowchart of frost fan control. When the heating operation is started, the elapsed time TD after the start of the heating operation is started in S1. After waiting for a certain time (TD2) in S2, it is determined in S3 whether or not the outside air temperature is lower than a predetermined temperature (Doadef). If Yes, the average value of the outdoor fan input is calculated in S4. Then, the process proceeds to S5, in which it is determined whether or not the time TD that has elapsed since the start of timing has reached a predetermined time (TD1). If Yes, the evaporating temperature (outdoor heat exchanger temperature) is a predetermined temperature in S6. It is determined whether it is less than (Tedef). If Yes in S6, the process proceeds to S7 so that the outdoor fan input maintains the average value of the input obtained in S4. Note that if any of S3, S5, and S6 is No, the normal operation is started. S1 to S7 are the starting conditions for the frost fan control, and S7 is the frost fan control operation.

<Operation after starting fan control during frosting>
In the frosting fan control, since the input to the outdoor fan 29 is constant during frosting, the rotational speed of the outdoor fan 29 is reduced according to the ventilation resistance, and an increase in blowing sound of the outdoor fan 29 is suppressed. However, since the frost on the outdoor heat exchanger 13 continues to grow, there is a limit to the suppression of blowing sound due to the decrease in the rotational speed of the outdoor fan 29. In addition, the fan control during frost formation is a control that suppresses the increase of the blowing sound while lowering the heating performance, so continuing the fan control during frost formation indefinitely significantly reduces the heating performance and makes the user insufficient for heating. It will make you feel. Therefore, it is necessary to switch to defrost control under a predetermined condition.

  FIG. 6 is a graph showing the relationship between the outdoor fan input, the outdoor fan rotation speed, the outdoor fan blowing sound, and the amount of frost formation when the frost fan control is continued. As shown in FIG. 6, when the amount of frost formation increases excessively, even if the rotation speed of the outdoor fan 29 continues to decrease, the increase amount of the blowing sound becomes large, and the blowing sound finally becomes the allowable limit value Qs. To reach. The rotational speed of the outdoor fan 29 at this time is set as a lower limit rotational speed Ns.

  Usually, when the outdoor heat exchanger temperature falls below the “target outdoor heat exchanger temperature” calculated from the operating frequency of the compressor 11 and the outside air temperature, the defrosting control is executed. In addition to this, in the present embodiment, when the control unit 4 is performing fan control at the time of frost formation, if the rotational speed of the outdoor fan 29 falls below the lower limit rotational speed Ns, the amount of frost formation increases and air flow is increased. It is determined that the sound has reached the permissible limit value Qs, and the frosting fan control is switched to the defrosting control. Hereinafter, the operation after the start of fan control during frost formation will be described with reference to the drawings.

  FIG. 7 is a flowchart from the start of fan control during frost formation to the start of defrost control. In FIG. 7, the control unit 4 keeps the input to the outdoor fan 29 constant in step S11. In step S12, the rotational speed N of the outdoor fan 29 is detected. In step S13, it is determined whether or not the rotational speed N of the outdoor fan 29 is lower than the lower limit rotational speed Ns. When it determines with Yes by step S13, it switches to defrost control by step S14. When it is determined No in step S13, the process returns to step S12.

  By this control, the rotational speed of the outdoor fan 29 can be reduced to such an extent that an air blowing sound suppression effect can be obtained and the user does not feel the lack of heating, so that the effect of fan control during frost formation can be maximized. Can do.

<First Modification>
In the above embodiment, when the rotational speed of the outdoor fan 29 falls below the lower limit rotational speed Ns, it is determined that the blowing sound has reached the allowable limit value Qs. However, the present invention is not limited to this. When the difference from the rotational speed of the outdoor fan 29 before frosting exceeds the allowable value L, it may be determined that the blowing sound has reached the allowable limit value Qs. In addition, the rotation speed of the outdoor fan 29 before frosting employ | adopts the average value of the rotation speed of the outdoor fan 29 sampled after the previous defrost control. Hereinafter, it demonstrates using drawing.

  FIG. 8 is a flowchart from the start of fan control during frost formation to the start of defrost control of the outdoor unit according to the first modification of the embodiment of the present invention. In FIG. 8, the control unit 4 keeps the input to the outdoor fan 29 constant in step S21. In step S22, the rotation speed Na of the outdoor fan 29 before frost formation is stored. In step S23, the rotational speed N of the outdoor fan 29 is detected. In step S24, it is determined whether or not the difference (Na−N) between the rotational speed Na of the outdoor fan 29 before frost formation and the detected rotational speed N of the outdoor fan 29 exceeds an allowable value L. When it determines with Yes by step S24, it switches to defrost control by step S25. When it determines with No by step S24, it returns to step S23.

<Second Modification>
In the first modified example, since it is determined to switch to defrosting control based on the instantaneous rotational speed of the outdoor fan 29, for example, natural wind against the blowing direction of the outdoor fan 29 hits the outdoor fan 29 and the rotational speed. May be switched to the defrost control by mistake when the power supply voltage decreases and the rotational speed of the outdoor fan 29 decreases instantaneously. Therefore, in the second modification, switching to defrost control is performed when the integrated value of the difference from the rotational speed of the outdoor fan 29 before frosting exceeds the allowable integrated value.

  FIG. 9 is a flowchart from the start of frost fan control to the start of defrost control of the outdoor unit according to the second modification of the embodiment of the present invention. In FIG. 9, the control unit 4 keeps the input to the outdoor fan 29 constant in step S31. In step S32, the rotation speed Na of the outdoor fan 29 before frost formation is stored. In step S33, the rotational speed Ni of the outdoor fan 29 is detected i times (for example, 5 times) every t seconds (for example, 60 seconds). In step S34, it is determined whether or not the integrated value Σ (Na−Ni) of the difference between the rotational speed Na of the outdoor fan 29 before frost formation and each detected rotational speed of the outdoor fan 29 exceeds the allowable integrated value M. To do. When it determines with Yes by step S34, it switches to defrost control by step S35. When it is determined No in step S34, the process returns to step S33.

<Features>
(1)
The outdoor unit 2 includes an outdoor heat exchanger 13, an outdoor fan 29, and a control unit 4. The outdoor heat exchanger 13 exchanges heat with air as an evaporator during heating operation. The outdoor fan 29 generates an air flow that passes through the surface of the outdoor heat exchanger 13. When frost formation on the outdoor heat exchanger 13 is detected or estimated, the control unit 4 performs frost formation fan control for reducing the rotational speed of the outdoor fan 29. For this reason, even if ventilation resistance increases by frost formation, since the increase amount of blowing sound is small, unpleasant noise is suppressed. Further, the frosting fan control is not executed until a predetermined time has elapsed from the start of the heating operation. For this reason, since the heating operation is maintained for a predetermined time, even when the operation is started with low outside air, warm air is provided.

(2)
The fan control at the time of frost formation of the outdoor unit 2 includes lowering the preset target rotational speed of the outdoor fan 29. Alternatively, lowering the upper limit of the input value supplied to the outdoor fan 29 is included. As a result, the number of rotations of the outdoor fan 29 decreases during frost formation, and the amount of increase in blowing sound is reduced. For this reason, noise is suppressed.

(3)
In the outdoor unit 2, the frosting fan control is executed when a predetermined time has elapsed from the start of the heating operation and the evaporation temperature of the outdoor heat exchanger 13 is lower than the predetermined temperature. Alternatively, when a predetermined time elapses from the start of the heating operation and the outside air temperature falls below the predetermined temperature, the frosting fan control is executed. Alternatively, the frosting fan control is executed when a predetermined time has elapsed from the start of the heating operation and the low-pressure side falls below the predetermined pressure. Alternatively, when a predetermined time has elapsed since the start of the heating operation and the on-time ratio in one cycle of the drive voltage supplied to the outdoor fan exceeds a preset on-time ratio, the fan control at the time of frost formation is executed. Is done. Alternatively, when a predetermined time elapses from the start of the heating operation and the rotational speed of the outdoor fan falls below a preset target rotational speed, the frosting fan control is executed. For this reason, frost formation is detected without using a special device, and blowing noise is suppressed.

(4)
In the outdoor unit 2, the average value of the input supplied to the outdoor fan 29 is calculated before the frosting fan control is started, and while the frosting fan control is being executed, the outdoor fan 29 is The average value of the input calculated previously is supplied. As a result, the rotational speed of the outdoor fan 29 is automatically reduced by the ventilation resistance due to frost formation. For this reason, the increase amount of blowing sound becomes small.

(5)
In the outdoor unit 2, when the fan control at the time of frost formation is performed, the defrosting operation is started when the rotational speed of the outdoor fan falls below the lower limit rotational speed Ns. In the frosting fan control, the heating capacity is reduced. Therefore, the rotation speed of the outdoor fan is monitored to prevent the heating capacity from falling beyond the allowable range. As a result, when frosting progresses to such an extent that an increase in blowing sound cannot be suppressed, the defrosting operation is started in a timely manner, so that the heating performance is restored before the user feels that heating is insufficient.

  Further, when the frosting fan control is performed, the defrosting operation is performed when the difference between the current rotational speed of the outdoor fan 29 and the rotational speed of the outdoor fan 29 before frosting exceeds the allowable value L. Even if started, the same effect as described above can be obtained.

  Further, when the frosting fan control is being performed, defrosting is performed when the integrated value of the difference between the rotational speed of the outdoor fan 29 and the rotational speed of the outdoor fan 29 before frosting exceeds the allowable integrated value M. Operation may be started. As a result, the defrosting operation is erroneously started even when a sudden back wind acts on the outdoor fan and its rotational speed suddenly decreases rapidly, or even when the power supply voltage decreases and the outdoor fan rotational speed suddenly decreases. Never happen.

  As described above, the outdoor unit of the present invention is effective as an outdoor unit of an air conditioner because the blowing sound of the outdoor fan is small during frost formation.

The refrigerant circuit of the air conditioning apparatus containing the outdoor unit which concerns on one Embodiment of this invention. Control block diagram of the air conditioner including the outdoor unit The graph showing the relationship between the outdoor fan input, outdoor fan rotation speed, and outdoor fan blowing sound when normal control is performed during frost formation. The graph showing the relationship between the outdoor fan input, outdoor fan rotation speed, and outdoor fan blowing sound when fan control is performed during frost formation. The flowchart of fan control at the time of frost formation. The graph showing the relationship between the outdoor fan input at the time of continuing fan control at the time of frost formation, the outdoor fan rotation speed, the outdoor fan blowing sound, and the amount of frost formation. The flowchart from the fan control start at the time of frost formation to the defrost control start. The flowchart from the fan control start at the time of frost formation of the outdoor unit which concerns on the 1st modification of embodiment of this invention to the start of defrost control. The flowchart from the fan control start at the time of frost formation of the outdoor unit which concerns on the 2nd modification of embodiment of this invention to the start of defrost control.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Air conditioning apparatus 2 Outdoor unit 3 Indoor unit 4 Control part 13 Outdoor heat exchanger

Claims (13)

An outdoor unit (2) of an air conditioner (1) to which an indoor unit (3) is connected,
An outdoor heat exchanger (13) for exchanging heat with air as an evaporator during heating operation;
An outdoor fan (29) for generating an air flow passing through the surface of the outdoor heat exchanger (13);
A controller (4) that performs frost fan control for reducing the rotational speed of the outdoor fan (29) when frost formation on the outdoor heat exchanger (13) is detected or estimated during heating operation. When,
An outdoor unit (2) equipped with The frosting fan control is not executed until a predetermined time has elapsed from the start of heating operation.
The outdoor unit (2) according to claim 1. The fan control at the time of frost formation includes lowering a preset target rotational speed of the outdoor fan (29),
The outdoor unit (2) according to claim 1. The frosting fan control includes lowering the upper limit of the input value supplied to the outdoor fan (29).
The outdoor unit (2) according to claim 1. The frosting fan control is executed when a predetermined time has elapsed from the start of heating operation and the evaporation temperature of the outdoor heat exchanger (13) is below a predetermined temperature.
The outdoor unit (2) according to claim 1. The fan control at the time of frost formation is executed when a predetermined time has elapsed from the start of the heating operation and the outside air temperature falls below a predetermined temperature.
The outdoor unit (2) according to claim 1. The fan control at the time of frosting is executed when a predetermined time has elapsed from the start of heating operation and the low-pressure side falls below a predetermined pressure,
The outdoor unit (2) according to claim 1. In the frosting fan control, a predetermined time has elapsed from the start of the heating operation, and the on-time ratio in one cycle of the drive voltage supplied to the outdoor fan (29) exceeds the preset on-time ratio. When executed,
The outdoor unit (2) according to claim 1. The frosting fan control is executed when a predetermined time has elapsed from the start of the heating operation and the rotational speed of the outdoor fan (29) falls below a preset target rotational speed.
The outdoor unit (2) according to claim 1. Prior to the start of the frosting fan control, an average value of the input supplied to the outdoor fan (29) is calculated, and while the frosting fan control is being executed, the outdoor fan ( 29) is supplied with the average value of the inputs;
The outdoor unit (2) according to claim 1. When the fan control at the time of frost formation is performed, if the rotational speed of the outdoor fan (29) falls below a preset lower limit rotational speed, a defrosting operation is started.
The outdoor unit (2) according to claim 1. When the fan control at the time of frost formation is performed, the difference between the rotation speed of the outdoor fan (29) and the rotation speed of the outdoor fan (29) before frost formation exceeds a preset allowable value. If it is, start defrosting operation.
The outdoor unit (2) according to claim 1. When the fan control at the time of frost formation is performed, an integrated value of a difference between the rotation speed of the outdoor fan (29) and the rotation speed of the outdoor fan (29) before frost formation is set in advance. If the total value is exceeded, start defrosting operation.
The outdoor unit (2) according to claim 1.

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