WO2007114243A1

WO2007114243A1 - Outdoor unit

Info

Publication number: WO2007114243A1
Application number: PCT/JP2007/056847
Authority: WO
Inventors: Hideki Sangenya; Katsunori Murata
Original assignee: Daikin Industries, Ltd.
Priority date: 2006-03-31
Filing date: 2007-03-29
Publication date: 2007-10-11
Also published as: JP2007292439A; AU2007232984B2; EP2012078A4; EP2012078A1; JP4270274B2; AU2007232984A1

Abstract

An outdoor unit for an air conditioner, where blowing noise of a fan is suppressed without reduction in operation efficiency. The outdoor unit (3) has 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 between refrigerant and air. The outdoor fan (29) produces airflow passing the surface of the outdoor heat exchanger (13). The control section (4) performs during-frost fan operation for reducing the speed of the outdoor fan (29) when frosting to the outdoor heat exchanger (13) is detected or considered.

Description

Specification

Outdoor unit

Technical field

TECHNICAL FIELD [0001] 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 rotation speed of the outdoor fan when the outdoor heat exchanger is frosted. The

Background art

[0002] Inside an outdoor unit of an air conditioner, an outdoor heat exchanger and an outdoor fan that generates an air flow are arranged. During 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 frost formation further progresses, it becomes a draft resistance and is likely to cause performance degradation. In order to prevent this performance deterioration, 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, patents). (Ref. 1). Patent Document 1: Japanese Patent Application Laid-Open No. 2004-218936

Disclosure of the invention

Problems to be solved by the invention

[0003] However, if the outdoor fan is maintained at the same rotation speed while the ventilation resistance is large while the force is strong, the blowing sound of the outdoor fan increases, which may cause discomfort to the user. Further, if the defrosting (defrosting) operation is performed earlier, the increase in 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 the fan which does not reduce driving | operation efficiency.

Means for solving the problem

[0004] An outdoor unit according to a first invention is an outdoor unit of an air conditioner to which the 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 outdoor heat transfer surface. The controller detects or estimates frost formation on the outdoor heat exchanger. When it is, the fan control at the time of frost formation is performed to reduce the rotation 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.

[0005] An outdoor unit according to a 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 for the heating operation start force.

Here, since the heating operation is maintained for a predetermined time, even if the operation is started with low outside air, it is possible to provide warm air.

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 reducing 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.

[0006] 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 an upper limit of an input value supplied to the outdoor fan. .

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 a predetermined time has elapsed since the start of heating operation, and the evaporating temperature of the outdoor heat exchanger has fallen below a predetermined temperature. Fan control is executed.

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

[0007] 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 a predetermined time has elapsed since the start of heating operation and the outside air temperature has fallen below a predetermined temperature, fan control during frost formation Is executed.

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, wherein 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 a predetermined pressure. .

Here, frost formation is detected without using a special device, and blowing noise is suppressed. The outdoor unit according to the eighth aspect of the invention is the outdoor unit according to the first aspect of the invention, and is When the fixed time has elapsed and the on-time ratio in one cycle of the drive voltage supplied to the outdoor fan exceeds the preset on-time ratio, fan control during frost formation is executed.

[0008] 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 from the start of heating operation, and the rotational speed of the outdoor fan is less than a preset target rotational speed. At that time, 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 the start of frost fan control, 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.

[0009] 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 is preset. If it falls below, start defrosting operation.

In this outdoor unit, since the heating capacity decreases due to fan control during frost formation, the number of rotations of the outdoor fan is monitored to prevent the heating capacity from exceeding a permissible range. For this reason, if frosting progresses to such an extent that the increase in the blowing noise cannot be suppressed, defrosting operation is started in a timely manner, so that the heating performance is restored before the user feels that the 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 the number of rotations of the outdoor fan and the number of rotations of the outdoor fan before frosting are determined when fan control is performed during frost formation. If the difference exceeds the preset tolerance, start defrosting operation.

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. To prevent it from falling. For this reason, the defrosting operation will be started in a timely manner when frosting has progressed to such an extent that the increase in blowing noise cannot be suppressed. Heating performance recovers before starting.

[0010] 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 the rotation speed of the outdoor fan and the rotation of the outdoor fan before frost formation are performed when fan control is performed during frost formation. When the integrated value of the difference from the number 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 is within the allowable range. It is prevented from falling over. 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. In addition, 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 suddenly drops, or the power supply voltage drops. However, even if the rotational speed of the outdoor fan drops suddenly, the defrosting operation will not be started by mistake.

The invention's effect

[0011] In the outdoor unit according to the first aspect of the present invention, even if the ventilation resistance increases due to frost formation, the amount of increase in 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 inventions, when the frost is formed, the rotational speed of the outdoor fan decreases, and the increase in the blowing noise becomes small. For this reason, noise is suppressed.

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

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

[0012] In the outdoor units according to the eleventh to thirteenth inventions, the defrosting operation is started in a timely manner when the frosting progresses to such an extent that the increase in the blowing noise cannot be suppressed. Therefore, before the user feels insufficient heating. Heating performance is restored.

Brief Description of Drawings

FIG. 1 is a refrigerant circuit of an air conditioner including an outdoor unit according to an embodiment of the present invention. [Figure 2] Control block diagram of the air conditioner including the outdoor unit

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.

FIG. 4 is a graph showing the relationship between outdoor fan input, outdoor fan rotation speed, and outdoor fan blowing sound when fan control is performed during frost formation.

FIG. 5 is a flowchart of fan control during frost formation.

FIG. 6 is a graph showing the relationship between outdoor fan input, outdoor fan rotation speed, outdoor fan blowing sound, and frost formation when fan control during frost formation is continued.

[FIG. 7] Fan control start force during frost formation Flow chart until defrost control starts.

FIG. 8 is a flowchart up to the start of defrosting control of the fan control start force during frosting of the outdoor unit according to the first modification of the embodiment of the present invention.

FIG. 9 is a flowchart up to the start of defrosting control of the fan control start force during frost formation of the outdoor unit according to the second modification of the embodiment of the present invention.

Explanation of symbols

[0014] 1 Air conditioner

2 Outdoor unit

3 Indoor unit

4 Control unit

13 Outdoor heat exchanger

BEST MODE FOR CARRYING OUT THE INVENTION

[0015] <Configuration of air conditioner>

FIG. 1 shows a refrigerant circuit of an air conditioner including an outdoor unit according to an embodiment of the present invention. The air conditioner 1 is a multi-room air conditioner, and has a configuration in which a plurality of indoor units 3 are connected in parallel to a single 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 connected in this order. It is a cycle. Here, the compressor 11 is a variable capacity inverter compressor that performs rotational speed control by an inverter. In addition, an accumulator 2 that separates liquid refrigerant and gas refrigerant is provided on the suction pipe side of the compressor 11. 0 is provided.

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 17a and 17b 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 17a is connected to the gas side closing valve 18, and a refrigerant communication pipe 17b is connected to the liquid side closing valve 19. These closing valves 18 and 19 are closed when the outdoor unit 2 and the indoor unit 3 are installed. 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.

[0016] The outdoor unit 2 is provided with an outdoor fan 29 for generating an air flow in order to promote heat exchange between the air and the outdoor heat exchanger 13.

The air conditioner 1 including the outdoor unit 2 of the present embodiment includes a number of temperature sensors that are 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 evaporating temperature sensor 113 during heating operation is attached to the outdoor heat exchanger 13 to detect the evaporating temperature Te, and the liquid pipe temperature sensor 117 is attached to the outlet side during heating operation of the indoor heat exchanger 16 to Detect tube temperature T1.

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 the temperature sensor and the detected value of the pressure sensor, the control unit 4 controls the operation of the air conditioner 1.

[0017] <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 selector valve 12, and the outdoor air Exchange heat and condense. The liquefied refrigerant is depressurized to a predetermined low pressure by the expansion valve 14 and is further evaporated by exchanging heat with room air by heat exchange in the room. 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. Further, the refrigerant evaporated and vaporized in the indoor heat exchanger 16 returns to the outdoor unit 2 through the refrigerant communication pipe 17a, and is sucked into the compressor 11.

[0018] (Heating operation)

During the heating operation, the four-way selector valve 12 is held in the state indicated by the broken line in FIG. The high-temperature and high-pressure gas refrigerant discharged from the compressor 11 flows into the indoor heat exchange of each indoor unit 3 through the four-way switching valve 12, and exchanges heat with the indoor air to condense and liquidate. . The indoor air heated by the condensation of the refrigerant is blown out into the room by the 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.

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 rotational speed is detected by a rotational speed sensor 129 that is provided in the motor 29a and is a Hall IC.

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 rotational speed decrease 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 normal control, the input is increased or decreased in order to keep the rotation speed of the outdoor fan 29 constant. In response to the increase or decrease in the rotation speed, the outdoor fan input is increased or decreased to maintain a constant rotation speed. Fig. 3 is a graph showing `` Relationship between outdoor fan input, outdoor fan rotation speed, and outdoor fan blowing sound under normal control during frost formation '', and the horizontal axis is the elapsed time after the start of heating operation. The vertical axis shows the outdoor fan input, outdoor fan speed, and outdoor fan blowing sound in descending order. Show. When the heating operation is started and the power reaches the predetermined time TD, the outdoor heat exchange

The frost starts to increase and the draft resistance starts to increase. In normal control, the outdoor fan input is increased to keep the rotational speed of the outdoor fan 29 constant so that the rotational speed does not drop due to draft resistance. For this reason, ventilation sound increases rapidly.

[0020] <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 through the frost detection unit 41, and performs outdoor heat exchange. The outdoor fan 29 is controlled via the outdoor fan control unit 42 by detecting or estimating the frost formation of the vessel 13.

In order to prevent an increase in the blowing noise of the outdoor fan 29, the control unit 4 keeps the outdoor fan input constant when the frosting of the outdoor heat exchanger 13 starts and the ventilation resistance starts to increase, and the outdoor fan speed is reduced. I try to go down. This is fan control at the time of frost formation, and this suppresses the increase of the 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 indicates the start of heating operation. The elapsed time is shown, and the vertical axis shows the outdoor fan input, outdoor fan rotation speed, and outdoor fan blowing sound in order from the bottom. When the heating operation is started and the predetermined time TD is passed, frosting 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 increase in the blowing noise becomes smaller than when the normal control is maintained.

FIG. 5 is a flowchart of fan control during frost formation. When the heating operation is started, the elapsed time TD after 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 timekeeping has reached the predetermined time (TD1). Determine whether the temperature is lower than Tedef. If S6 is Yes, proceed to S7 so that the average value of the input calculated by the outdoor fan input force S4 is maintained. If any of S3, S5, and S6 is No, the system enters normal operation. S1 to S7 are the conditions for starting fan control during frost formation, and S7 is the fan control operation during frost formation.

[0022] <Operation after starting fan control during frost formation>

In the fan control during frost formation, the input to the outdoor fan 29 is constant during frost formation. Therefore, the rotational speed of the outdoor fan 29 decreases according to the ventilation resistance, and the increase in the 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 the blowing sound due to the decrease in the rotational speed of the outdoor fan 29. In addition, fan control during frost formation is a control that suppresses an increase in blowing noise while lowering the heating performance, so continuing the fan control during frost formation indefinitely will significantly reduce the heating performance and give the user You will feel a lack of heating. 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 fan control during frost formation is continued. As shown in Fig. 6, if the amount of frost formation increases excessively, even if the rotational speed of the outdoor fan 29 continues to decrease, the amount of increase in the blowing noise increases, and the blowing noise finally reaches the allowable limit value Qs. To reach. The rotation speed of the outdoor fan 29 at this time is defined as the lower limit rotation speed Ns.

[0023] Normally, 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 outdoor air temperature, the defrosting control is executed. . In this embodiment, in this embodiment, when the control unit 4 performs fan control during frost formation, if the rotational speed of the outdoor fan 29 falls below the lower limit rotational speed Ns, the frost formation amount increases. It is determined that the blowing sound has reached the allowable limit value Qs, and the fan control during frost formation is switched to defrost 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 at 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 has fallen below the lower limit rotational speed Ns. When it determines with Yes at step S13, it switches to defrost control at step S14. No in step S13 If set, return to step S12.

[0024] With this control, the rotational speed of the outdoor fan 29 can be reduced to such an extent that a blowing sound suppression effect is obtained and the user does not feel the lack of heating, so the effect of fan control during frost formation is maximized. To the limit.

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. Note that, as the rotation speed of the outdoor fan 29 before frost formation, an average value of the rotation speeds of the outdoor fan 29 sampled after the previous defrost control is adopted. 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 at step S21. In step S22, the rotational 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. If YES in step S24, switch to defrost control in step S25. If it is determined No in step S24, the process returns to step S23.

In the first modification, since it is determined to switch to defrost control based on the instantaneous rotational speed of the outdoor fan 29, for example, natural wind against the air blowing direction of the outdoor fan 29 hits the outdoor fan 29 and rotates. If the number decreases instantaneously, or if the power supply voltage decreases and the rotational speed of the outdoor fan 29 decreases instantaneously, there is a possibility of erroneously switching to defrost control. Therefore, in the second modification, switching to defrosting control is performed when the integrated value of the difference from the rotational speed of the outdoor fan 29 before frosting exceeds the allowable volume calculation value.

FIG. 9 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 second modification of the embodiment of the present invention. In FIG. 9, the control unit 4 performs step S3. 1 keeps the input to the outdoor fan 29 constant. In step S32, the rotational 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 the integrated value ∑ (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. judge. If it is determined as Yes in step S34, switch to defrost control in step S35. If it is determined No in step S34, return to step S33.

(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 passing through the outdoor heat exchange surface. When the frost formation on the outdoor heat exchanger 13 is detected or estimated, the control unit 4 performs frost formation fan control for reducing the rotation speed of the outdoor fan 29. For this reason, even if ventilation resistance increases due to frost formation, unpleasant noise is suppressed because the amount of increase in blowing noise is small. In addition, the fan control during frost formation is not executed until the heating operation start force predetermined time elapses. For this reason, since the heating operation is maintained for a predetermined time, even if 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 target rotational speed of the outdoor fan 29 set in advance. Alternatively, it includes lowering the upper limit of the input value supplied to the outdoor fan 29. As a result, the rotational speed of the outdoor fan 29 decreases during frost formation, and the amount of increase in the 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 elapses in the heating operation start force and the evaporation temperature of the outdoor heat exchange is lower than the predetermined temperature. Alternatively, when a predetermined time has elapsed from the start of heating operation and the outside air temperature falls below a predetermined temperature, fan control during frost formation is executed. Alternatively, when a predetermined time elapses after the start of the heating operation and the low-pressure side falls below the predetermined pressure, the frosting fan control is executed. Or from the start of heating operation When the fixed time has elapsed and the on-time ratio in one cycle of the drive voltage supplied to the outdoor fan exceeds the preset on-time ratio, fan control during frost formation is executed. Alternatively, the frosting fan control is executed when the heating operation start force has also passed the predetermined time and the outdoor fan speed falls below a preset target speed. For this reason, frost formation is detected without using a special device, and blowing noise is suppressed.

[0028] (4)

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

(Five)

In the outdoor unit 2, the defrosting operation is started when the rotation speed of the outdoor fan falls below the lower limit rotation speed Ns during fan control during frost formation. The fan control during frosting reduces the heating capacity, so the outdoor fan speed is monitored to prevent the heating capacity from falling beyond the allowable range. As a result, when frosting progresses to the 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.

[0029] Further, when the fan control at the time of frost formation is being performed, this is excluded when the difference between the current rotation speed of the outdoor fan 29 and the rotation speed of the outdoor fan 29 before frosting exceeds the allowable value L. Even if the frost operation is started, the same effect as described above can be obtained.

In addition, when fan control during frost formation is performed, defrosting occurs 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 frost exceeds the allowable integrated value M. You may start driving. As a result, even if a sudden back wind acts on the outdoor fan and its rotation speed suddenly decreases, or even if the power supply voltage decreases and the outdoor fan rotation speed suddenly decreases, the defrosting operation is mistakenly performed. Will never start.

Industrial applicability

[0030] As described above, the outdoor unit according to the present invention generates a low noise from the outdoor fan during frost formation. It is effective as an outdoor unit for an air conditioner.

Claims

The scope of the claims

[1] An outdoor unit (2) of an air conditioner (1) to which an indoor unit (3) is connected,

An outdoor heat exchanger (13) that performs heat exchange with air as an evaporator during heating operation, an outdoor fan (29) that generates an air flow that passes through the surface of the outdoor heat exchanger (13), and during the heating operation, A controller (4) that performs fan control during frost formation to reduce the rotational speed of the outdoor fan (29) when frost formation on the outdoor heat exchanger (13) is detected or estimated. Outdoor unit (2).

[2] The fan control during frost formation is not executed until a predetermined time has elapsed from the start of heating operation.

The outdoor unit (2) according to claim 1.

[3] 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.

[4] The fan control during frost formation includes lowering an upper limit of an input value supplied to the outdoor fan (29).

The outdoor unit (2) according to claim 1.

[5] The fan control at the time of frost formation is executed when a predetermined time has elapsed from the start of heating operation and the evaporation temperature of the outdoor heat exchanger (13) falls below a predetermined temperature.

The outdoor unit (2) according to claim 1.

[6] The fan control at the time of frost formation is executed when the heating operation start force for a predetermined time has elapsed and the outside air temperature falls below the predetermined temperature.

The outdoor unit (2) according to claim 1.

[7] The fan control at the time of frost formation is executed when a predetermined time elapses in the heating operation start force and the low pressure side falls below the predetermined pressure.

The outdoor unit (2) according to claim 1.

[8] In the frost fan control, a predetermined time elapses from the start of the heating operation, and the outdoor fan (

This is executed when the ON time ratio in one cycle of the drive voltage supplied to (29) exceeds the preset ON time ratio. The outdoor unit (2) according to claim 1.

[9] In the frosting fan control, a predetermined time has elapsed from the start of heating operation, and the outdoor fan (

The outdoor unit (2) according to claim 1, which is executed when the rotational speed of 29) falls below a preset target rotational speed.

[10] Before the frosting fan control is started, an average value of inputs supplied to the outdoor fan (29) is calculated, and while the frosting fan control is being executed, The average value of the input is supplied to an outdoor fan (29),

The outdoor unit (2) according to claim 1.

[11] When the fan control at the time of frost formation is performed, if the rotation speed of the outdoor fan (29) falls below a preset lower limit rotation speed, a defrosting operation is started.

The outdoor unit (2) according to claim 1.

[12] When the fan control at the time of frost formation is performed, 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 value is exceeded, start defrosting operation.

The outdoor unit (2) according to claim 1.

[13] When the fan control during 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. Defrosting operation is started when the allowable accumulated value exceeds

The outdoor unit (2) according to claim 1.