JPH10132364A - Air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To protect a fan motor for rotating and driving an air supply fan provided in an outdoor unit from the rise of temperature. SOLUTION: When the desired rotating speed of a fan motor is set, a step of duty ratio for driving to obtain the desired rotating speed is set, an upper limit value set for each outside air temperature relative to the desired rotating speed is read (steps 160 to 162) and the feedback control of the fan motor is carried out so as to maintain the desired rotating speed (steps 164 to 172). At this time, when the step of duty ratio is raised, whether the set step of duty ratio reaches the upper limit value or not is recognized (step 174). When it reaches the upper limit value, the fan motor is stopped (step 176). Thus, the high temperature of the fan motor due to self-heat generation is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner for conditioning indoor air using a refrigeration cycle, and more particularly to an air conditioner for controlling a fan motor for blowing heat to a heat exchanger constituting a refrigeration cycle.

[0002]

2. Description of the Related Art A conventional air conditioner (hereinafter referred to as "air conditioner") efficiently cools or heats a room and saves energy by controlling the capacity of a compressor provided in a refrigeration cycle. You can do it.

The temperature of the refrigerant circulated in the refrigeration cycle during operation of the compressor is increased by being compressed and discharged by the compressor. To reduce the temperature of the refrigerant, air is blown to a heat exchanger (condenser) in the refrigeration cycle.

[0004] The temperature of the condenser (heat exchanger) (the temperature of the refrigerant discharged from the compressor) is affected by the capacity of the compressor and the ambient temperature. Therefore, in order to reduce the temperature of the refrigerant to an appropriate temperature, Generally, the rotation speed of the blower fan is controlled.

Conventionally, an AC motor has been used as a fan motor for driving the blower fan.
Motors have large slip loss and poor operating efficiency. Also, it is easy to be connected to the circuit directly connected to the AC power supply,
For protection against overcurrent, a mechanical protection means such as a thermal fuse is required.

On the other hand, there is a method using a DC motor as a fan motor. Since the DC motor has high operation efficiency and can use an electric overcurrent prevention mechanism, no mechanical protection means such as a thermal fuse is required, and the number of components can be reduced.

[0007] When a propeller fan is used as a blower fan in any of the motors, the number of rotations is reduced by receiving a reverse wind. At this time, by increasing the power supplied to the fan motor, the blower fan can be maintained at the set rotation speed.

[0008]

However, when the condenser is installed outside the room, the temperature of the fan motor itself is greatly affected by the outside air. For this reason, even if the temperature rise due to the self-heating of the fan motor is suppressed, there is a problem that the temperature of the fan motor becomes abnormally high. Further, when the number of rotations decreases due to the headwind, there is a problem that the applied voltage becomes abnormally high by the feedback control.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described circumstances, and is not required to provide any special parts, because the temperature rise and the applied voltage increase due to the self-heating of the fan motor when the blower fan receives a reverse wind. An object is to propose an air conditioner that can drive a fan motor while reliably protecting the motor.

[0010]

According to the present invention, there is provided an air conditioner configured to operate a refrigeration cycle to achieve air conditioning in a room. When controlling the rotation speed of the fan motor that blows to the exchanger by changing the supply power, the fan motor maintains the target rotation speed in a range equal to or less than the upper limit of the power set according to the target rotation speed. It is characterized by feedback control.

According to the present invention, when performing feedback control so as to maintain the rotation speed of the fan motor at the target rotation speed, the upper limit value of the electric power for driving the fan motor is set for each target rotation speed of the fan motor. ing. Since the upper limit of the electric power for driving the fan motor is set and controlled so as not to exceed this upper limit, even if the load of the fan motor becomes large, the fan motor itself can be installed without any special parts. The fan motor can be reliably protected from temperature rise due to heat generation.

Further, the present invention is characterized in that the upper limit is further corrected according to the outside air temperature.

According to the present invention, the upper limit value of the electric power to be supplied for each target rotation speed of the fan motor is further corrected according to the outside air temperature. The temperature of the fan motor is the sum of the outside air temperature and the temperature due to the amount of self-generated heat. Further, the self-heating amount increases in accordance with the electric power for driving the fan motor.

On the other hand, by correcting the driving power set in accordance with the target rotation speed in accordance with the outside air temperature, it is possible to prevent the temperature of the fan motor from becoming abnormally high, and to prevent the fan motor from rising in temperature. Can be reliably protected.

In the air conditioner provided with the fan motor, it is preferable to stop the fan motor when the driving power reaches the set upper limit. Also,
When the blower fan rotationally driven by the fan motor is receiving a headwind, the operation of the air conditioner may be continued by stopping the blower fan, since the heat exchanger receives the headwind.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below.

FIG. 1 shows a refrigeration cycle of an air conditioner (hereinafter referred to as "air conditioner 10") applied to the present embodiment. The air conditioner 10 includes an indoor unit 12 and an outdoor unit 14 installed in a conditioned room, and sends an operation signal from a remote control switch (not shown) to the indoor unit 12 to thereby control the air conditioner 1.
In addition to setting the operation mode, operation conditions, etc. of 0,
Start / stop operation is possible.

The indoor unit 12 and the outdoor unit 14 are connected by a thick refrigerant pipe 16A for circulating a refrigerant and a thin refrigerant pipe 16B.
One end of each of 16B is connected to a heat exchanger 18 provided in the indoor unit 12.

The other end of the refrigerant pipe 16A is connected to the outdoor unit 1
4 is connected to the valve 20A. This valve 20A
Is connected to the four-way valve 24 via the muffler 22A. Each of the four-way valves 24 has a compressor 26.
Accumulator 28 and muffler 22B connected to
Is connected. Further, the outdoor unit 14 is provided with a heat exchanger 30. One end of the heat exchanger 30 is connected to the four-way valve 24, and the other end is connected to the valve 20B via a cooling / heating capillary tube 32, a strainer 34, an electric expansion valve 36, and a modulator 38.

The other end of the refrigerant pipe 16B is connected to the valve 20B, thereby forming a closed circulation path for the refrigerant forming a refrigeration cycle between the indoor unit 12 and the outdoor unit 14, and a compressor. In the operation 26, the refrigerant is circulated, and the operation by the refrigeration cycle is performed.

In the air conditioner 10, the operation mode is switched between a cooling mode (including a dry mode) and a heating mode by switching the four-way valve 24. Further, by controlling the valve opening of the electric expansion valve 36, the evaporation temperature of the refrigerant is adjusted. In FIG. 1, the arrows indicate the flows of the refrigerant in the cooling mode (cooling operation) and the heating mode (heating operation).

FIG. 2 shows a schematic cross section of the indoor unit 12. The interior of the indoor unit 12 is covered by a casing 42 that is locked above and below (up and down in the plane of FIG. 2) a mounting base 40 fixed to an indoor wall surface (not shown). In this casing 42, a cross flow fan 44 is arranged at the center. Heat exchanger 18
Is disposed from the front side to the top side of the cross flow fan 44, and a filter 48 is provided between the heat exchanger 18 and a suction port 46 formed from the front side to the top side of the casing 42. Are located. An outlet 50 is formed at a lower portion of the casing 42.

Thus, in the indoor unit 12, the air in the room is sucked in from the suction port 46 by the rotation of the cross flow fan 44, passes through the filter 48 and the heat exchanger 18, and then blows out from the outlet port 50 toward the room. Is done. In the indoor unit 12, the heat exchanger 18 is cooled (acting as an evaporator) or heated (acting as a condenser) by a refrigeration cycle, and when air sucked from the room passes through the heat exchanger 18, The heat is cooled or heated to a predetermined temperature by the heat exchanger 18. The air is blown into the room to achieve indoor air conditioning.

A left and right flap 52 and an upper and lower flap 54 are provided in the air outlet 50.
The direction of the conditioned air blown out can be changed by the second and upper and lower flaps 54.

As shown in FIG. 3, the indoor unit 12
Is provided with a power supply board 56, a control board 58, and a power relay board 60. On a power supply board 56 to which electric power for operating the air conditioner 10 is supplied, a motor power supply 62, a control circuit power supply 64, a serial power supply 66, and a drive circuit 68 are provided. The control board 58 is provided with a serial circuit 70, a drive circuit 72, and a microcomputer 74.

The drive circuit 68 of the power supply board 56 is connected to a fan motor 76 (for example, a DC brushless motor) for driving the cross flow fan 44, and receives a control signal from a microcomputer 74 provided on the control board 58. Drive power is supplied from the motor power supply 62 accordingly. At this time, the microcomputer 74 controls so that the output voltage from the drive circuit 68 is changed in a range of 12 V to 36 V in 256 steps.

The drive circuit 72 of the control board 58 is connected to an upper and lower flap motor 78 for operating the power relay board 60 and the upper and lower flaps 54. The power relay board 60 is provided with a power relay 80, a temperature fuse, and the like. The power relay 80 is operated by a signal from the microcomputer 74 to open and close a contact 80A for supplying power to the outdoor unit 14. Air conditioner 1
In the case of 0, the electric power is supplied to the outdoor unit 14 when the contact 80A is closed, so that the outdoor unit 14 is operated.

The upper and lower flap motors 78 are controlled in accordance with a control signal from the microcomputer 74 to operate the upper and lower flaps 5.
Operate 4. When the upper and lower flaps 54 are swung in the vertical direction, the outlet 50 of the indoor unit 12 is opened.
The direction in which air is blown out of the apparatus is changed in the vertical direction. The operation of the upper and lower flaps 54 can be fixed so that the blowing wind is directed in an arbitrary direction, but in the automatic mode, the wind direction changes randomly.

As described above, in the indoor unit 12 of the air conditioner 10, by controlling the rotation of the cross flow fan 44 and the operation of the upper and lower flaps 54, the air flow is controlled to a desired air volume and direction or to make the room comfortable. The air conditioned by the air volume and the wind direction can be blown into the room.

The microcomputer 74 and a serial circuit 70 connected to the serial power supply 66 of the power supply circuit 56 are connected to the outdoor unit 14. The microcomputer 74 communicates with the outdoor unit 14 via the serial circuit 70. Serial communication is performed to control the operation of the outdoor unit 14.

The indoor unit 12 is provided with a display board 82 having a receiving circuit for receiving an operation signal from a remote control switch (not shown) and a display LED for operation display. 74. Thus, the operation signal from the remote control switch is input to the microcomputer 74.

Further, the microcomputer 74 is connected to a room temperature sensor 84 for detecting the room temperature and a heat exchange temperature sensor 86 for detecting the coil temperature of the heat exchanger 18, and a service LED provided on the control board 58. And an operation changeover switch 88 are connected. The operation changeover switch 88 is used for switching between a normal operation and a test operation performed at the time of maintenance or the like, and can cut off the supply of the operation power to the air conditioner 10 by opening a contact of the power switch 88A. Normally, the operation changeover switch 88
Is set to normal operation. Service LED
Is turned on at the time of maintenance to inform a service person of the self-diagnosis result.

The indoor unit 12 is connected to the outdoor unit 14 via terminals 90A, 90B, 90C of the terminal board 90.

On the other hand, as shown in FIG. 4, the outdoor unit 14 is provided with a terminal plate 92, and the terminals 92A, 92B, 92C of the terminal plate 92 are respectively connected to the terminals 90A of the terminal plate 90 of the indoor unit 12. , 90B,
90C. Thereby, the outdoor unit 1
Operation power is supplied to the indoor unit 12 from the indoor unit 12, and serial communication with the indoor unit 12 is possible.

The outdoor unit 14 includes a rectifying board 9
4. A control board 96 is provided. The control board 96 includes a microcomputer 98 and a noise filter 10.
0A, 100B, and 100C, a serial circuit 102, a switching power supply 104, and the like are provided.

The rectifying board 94 includes a noise filter 100
A rectifies the power supplied through the A
The data is smoothed via 00B and 100C and output to the switching power supply 104. The switching power supply 104 is connected to the inverter circuit 106 together with the microcomputer 98.
Thus, power having a frequency corresponding to the control signal output from the microcomputer 98 is output from the inverter circuit 106 to the compressor motor 108, and the compressor 26 is driven to rotate.

The microcomputer 98 is connected to the inverter circuit 1
The frequency of the power output from 06 is off or 14Hz
The control is performed so as to be in the range described above (the upper limit is determined by the upper limit of the operating current).
08, that is, the rotation speed of the compressor 26 is changed,
The operating capacity of the compressor 26 (the cooling / heating capacity of the air conditioner 10) is controlled.

A motor 120 for opening and closing the four-way valve 26 and the electric expansion valve 36 is connected to the control board 96. As the motor 120, for example, a stepping motor is used, and among the stepping motors, a stepping motor having a relatively small cost of about 50 steps is used. The outdoor unit 14 has an outside air temperature sensor 1 for detecting an outside air temperature.
12. A coil temperature sensor 114 for detecting the temperature of the refrigerant coil of the heat exchanger 30 and a compressor temperature sensor 116 for detecting the temperature of the compressor 26 are provided.
These are connected to the microcomputer 98.

The microcomputer 98 switches the four-way valve 24 in accordance with the operation mode, controls the control signal from the indoor unit 12, the outside air temperature sensor 112, and the coil temperature sensor 11.
4 and the operation frequency of the compressor motor 108 (capacity of the compressor 26) and the like are controlled based on the detection result of the compressor temperature sensor 116. By the way, as shown in FIG. 1, the outdoor unit 14 is provided with a blower fan 122 facing the heat exchanger 30. In the outdoor unit 14, the outside air is blown toward the heat exchanger 30 by rotating the blower fan 120 to cool the heat exchanger 30.

That is, the temperature of the refrigerant is increased by being compressed by the compressor 26. In the refrigeration cycle, the refrigerant whose temperature has increased is sent to the heat exchanger 30. In the heat exchanger 30, heat exchange is performed between air passing between a number of fins (not shown) and a refrigerant passing through the inside of the heat exchanger 30, thereby cooling the refrigerant. At this time, the cooling capacity of the refrigerant in the heat exchanger 30 is:
It increases as the amount of air passing through the heat exchanger 30 increases. For this reason, by rotating the blower fan 122 to blow air toward the heat exchanger 30, the cooling capacity of the refrigerant in the heat exchanger 30 can be increased.

On the other hand, as shown in FIG. 4, the control board 96 of the outdoor unit 14
Is connected to a fan motor 110 that rotationally drives the motor.
The fan motor 110 is driven according to a target rotation speed set by the microcomputer 98.

The microcomputer 98 controls the fan motor 110 according to the rotation speed (capacity) of the compressor 26 and the outside air temperature.
Is determined. As the fan motor 110, a D which rotates at a rotation speed corresponding to the supplied voltage is used.
C motor is used.

The microcomputer 98 controls the number of revolutions of the fan motor 110 by applying a pulse of a constant voltage to the fan motor 110, and sets a step of the duty ratio in advance.
When the target rotation speed of 0 is determined, the step of the duty ratio is selected so as to reach the determined target rotation speed. PWM is performed so that the duty ratio of the selected step is achieved, and the fan motor 110 is driven. The average voltage of the voltage applied to the fan motor 110 is determined by the duty ratio, and the fan motor 110 is driven to rotate at a rotation speed corresponding to the average voltage.

On the other hand, in the microcomputer 98, the fan motor 1
10, the number of revolutions when the fan motor 110 is rotationally driven is detected, and the actual number of revolutions is compared with the set number of target revolutions. It is determined whether the rotation speed is lower or higher. If the rotation speed to be implemented is higher than the set target rotation speed, the duty ratio for driving the fan motor 110 is reduced by one step. When the actual rotation speed of the fan motor 110 is lower than the set target rotation speed, the duty ratio for driving the fan motor 110 is increased by one step, and the set target rotation speed and the actual fan motor 110 So that the rotation speeds of them are the same.

Further, as shown in FIG. 5, in the microcomputer 98, the upper limit of the voltage (duty ratio) is set according to the outside air temperature in order to limit the upper limit of the electric power for driving the fan motor 110. That is, the fan motor 11
By performing feedback control of 0, when the duty ratio (average voltage) increases, the set upper limit value is not exceeded. The fan motor 110 generates self-heating in response to an increase in applied power (voltage),
The temperature of the fan motor 110 itself increases. In order to suppress this temperature rise, an upper limit value of the voltage is set.

Generally, the temperature of the fan motor 110 (DC motor) is the sum of the temperature of the outside air and the temperature due to self-heating. From here, in the microcomputer 98, the fan motor 1
The upper limit of the duty ratio with respect to the set target rotational speed is set from the upper limit of the temperature rise due to self-heating and the upper limit of the temperature of the fan motor 110. The upper limit is set, for example, so that the temperature rise due to self-heating of the fan motor 110 is 45 ° C. or less,
The temperature of the fan motor 110 is prevented from exceeding 110 ° C.

Thus, for example, when the number of rotations of the fan motor 110 decreases due to the reverse wind, the blower fan 122 receives a force rotating in the direction opposite to the rotation direction of the fan motor 110, Since the step of the duty ratio is increased in order to reach the set target rotation speed, even if the temperature of the fan motor 110 rises, the temperature of the fan motor 110 is prevented from exceeding the set upper limit.

In FIG. 5, as an example, the outside air temperature 30
The upper limit of the duty ratio with respect to the set target rotation speed at 40 ° C., 40 ° C., and 50 ° C. is shown. The difference between the respective graphs indicates the temperature due to the self-heating of the fan motor 110 for each target rotation speed. 10 ° C rise
Is the difference in the steps of the duty ratio. Number of rotations of fan motor 110 (number of rotations of blower fan 122)
Is set between the rotation speed RMIN and the rotation speed RMAX.

The operation of the present embodiment will be described below.

The air conditioner 10 can set an air cleaning operation and the like in addition to the cooling operation, the heating operation, and the dry operation, and starts the operation based on the set operation mode.
At this time, when the automatic operation is set, the air conditioner 10
The operation mode is selected based on the outside air temperature or the indoor temperature and the set temperature, and the air conditioning operation is performed.

When the air conditioner 10 is operated to start the air conditioning operation, the set temperature and the room temperature are measured, and based on the measurement results, the operating frequency of the compressor 26, the air volume (the number of rotations of the cross flow fan 44), and the like. Is set, and the air-conditioning operation is performed based on the setting result. Thus, the interior of the conditioned room in which the indoor unit 12 is provided is efficiently brought into a desired air-conditioning state, and this air-conditioning state is maintained.

Further, the outdoor unit 14 of the air conditioner 10
Then, it is determined whether or not the heat exchanger 30 needs to be cooled according to the outside air temperature and the rotation speed (operating frequency) of the compressor 26, and when it is determined that the heat exchanger 30 needs to be cooled, The required rotation speed of the blower fan 122 (the target rotation speed of the fan motor 110) is set in accordance with the temperature and the operating frequency of the compressor 26.
Is controlled and driven so as to reach the set target rotation speed.

When the blower fan 112 is rotationally driven, the refrigerant compressed by the compressor 26 to have a high temperature and sent to the heat exchanger 30 is forcibly forced by the blower fan 112 when passing through the heat exchanger 30. Heat is exchanged with the air supplied to the air conditioner, and the cooling is efficiently and reliably performed.

FIGS. 6 and 7 show the outline of the control of the blower fan 122 in the air conditioner 10 and the outline of the driving of the fan motor 110.

The flowchart of FIG. 6 is executed while the air conditioner 10 is operating (for example, during a cooling operation). In the first step 150, the outside air temperature sensor 112 detects the temperature of the outside air in which the outdoor unit 14 is installed. Read. In step 152, the rotational speed of the compressor 26, that is, the operating frequency of the compressor motor 108 is read. Thereafter, in step 154, it is determined from the outside air temperature and the operating frequency of the compressor 26 whether or not it is necessary to cool the refrigerant passing through the heat exchanger 30 by rotating the blower fan 122.

Here, when it is determined that the rotation of the blower fan 122 is necessary (Yes in step 154), the process proceeds to step 156, where the temperature of the blower fan 122 is determined based on the outside air temperature and the operating frequency of the compressor 26. Rotation speed R
(Target rotation speed) is set. The necessity of the rotation drive of the blower fan 122 and the setting of the target rotation speed R are repeatedly performed at a predetermined timing.

On the other hand, the flowchart shown in FIG.
It is repeatedly executed each time the rotation speed R of the blower fan 122 (the target rotation speed of the fan motor 110) is set.
The step of the duty ratio is set according to the target rotation speed R of the (fan motor 110). For example, as shown in FIG. 5, when the rotational speed is Rn, a step Sn corresponding to the rotational speed Rn is set. In step 162, an upper limit value corresponding to the outside air temperature is read. For example, when the outside air temperature is 40 ° C.,
The upper limit Mn corresponding to ° C is read, and the upper limit is corrected according to the outside air temperature.

Thereafter, in step 164, the fan motor 110 is driven in step Sn of the set duty ratio.

When the fan motor 110 is driven, feedback control of the fan motor 110 is performed. For example,
The actual rotation speed r of the fan motor 110 is detected (step 166), and the detected rotation speed r and the set target rotation speed R are determined.
Are compared (step 168). Here, when the actual rotational speed r is higher than the set target rotational speed R, the process proceeds to step 170, in which the step of the duty ratio is reduced by one step (step Sn-1), and the fan motor 110 is turned on. Drive. As a result, the actual rotation speed of the fan motor 110 decreases, and the set target rotation speed R
Can be adjusted to

The number of revolutions r of the fan motor 110 may be detected by providing a pulse generator to the fan motor 110 and counting the number of pulses generated by the pulse generator. Also, the fan motor 11
When a generator that outputs a voltage corresponding to the rotation speed r is provided at 0, whether the rotation speed is calculated from the output voltage of the generator, or whether the output voltage of the generator is in accordance with the set duty ratio step It is sufficient to judge from.

On the other hand, when it is determined that the actual rotational speed r is lower than the set target rotational speed R, step 172 is executed.
Then, the step of the duty ratio is increased by one step (steps Sn + 1, Sn + 2,...). As a result, the actual rotation speed r of the fan motor 110 is increased,
The target rotation speed R is set closer to the set target rotation speed R.

When the step of the duty ratio is increased by one step, the process proceeds to step 174 to check whether or not the step of the set duty ratio has reached the upper limit Mn with respect to the set rotation speed Rn. ing. Here, when the step of the duty ratio reaches step Sm corresponding to the upper limit Mn, an affirmative determination is made in step 174 and the process proceeds to step 176. In this step 176, when a large load acts on the fan motor 110 to increase the power supplied to maintain the fan motor 110 at the set rotation speed R, the fan motor 11
The fan motor 110 is stopped when it is determined that the temperature of 0 has risen too much.

That is, since the blower fan 122 receives the backward wind, the rotation speed r of the fan motor 110 does not increase, and if the rotation speed r of the fan motor 110 is to be increased, the self-heating amount of the fan motor 110 increases. Resulting in. If the self-heating amount of the fan motor 110 at this time reaches the upper limit, the microcomputer 98 forcibly stops the fan motor 110 to prevent the temperature due to the self-heating amount of the fan motor 110 from exceeding the upper limit. I have.

On the other hand, in the air conditioner 10, the fan motor 1
Since the upper limit for forcibly stopping the fan 10 is set for each outside air temperature, the temperature rise due to self-heating of the fan motor 110 and the outside air temperature cause the fan motor 11
It is possible to prevent the temperature of 0 from exceeding a predetermined upper limit (for example, an allowable temperature).

That is, when the upper limit is set only for the temperature rise due to self-heating of the fan motor 110, if the outside air temperature is high, even if the temperature rise due to self-heating is relatively low,
The temperature of the fan motor 110 will increase significantly. On the other hand, by controlling the drive power by correcting the upper limit value according to the outside air temperature, the fan motor 11
It is possible to reliably prevent the temperature of 0 from exceeding the allowable range.

It should be noted that the fan motor 110
When the load on the air conditioner becomes large, the air is supplied to the heat exchanger 30 by the headwind, and the cooling of the refrigerant in the heat exchanger 30 becomes possible. Therefore, it is not necessary to stop the operation of the air conditioner 10. However, it is preferable to stop the operation of the air conditioner 10 when the increase in the step of the duty ratio for driving the fan motor 110 is a condition other than the reverse wind.

As described above, the upper limit value of the step of the duty ratio when driving the fan motor 110, that is,
By setting the upper limit of the driving power of the fan motor 110, it is possible to prevent the self-heating amount of the fan motor 110 from increasing. Further, by correcting the upper limit value according to the outside air temperature, it is possible to prevent the temperature of the fan motor 110 from greatly increasing due to self-heating and exceeding the allowable temperature, thereby preventing the fan motor 110
Can be reliably protected.

The above description shows one example of the present invention and does not limit the configuration of the present invention. INDUSTRIAL APPLICABILITY The present invention can be applied to air conditioners of various configurations for achieving air conditioning of a conditioned room by a refrigeration cycle, and it is possible to prevent operation from being hindered by a temperature rise of a fan motor that drives a blower fan provided in an outdoor unit. Thus, the air-conditioning operation can be performed so that the room to be air-conditioned becomes comfortable.

[0069]

As described above, according to the present invention, it is possible to reliably protect a fan motor from a temperature rise caused by self-heating of a fan motor for driving a blower fan provided in an outdoor unit without using special parts. The excellent effect that can be obtained is obtained.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a refrigeration cycle of an air conditioner applied to the present embodiment.

FIG. 2 is a schematic sectional view showing an indoor unit.

FIG. 3 is a block diagram schematically illustrating a circuit configuration of an indoor unit.

FIG. 4 is a block diagram schematically illustrating a circuit configuration of the outdoor unit.

FIG. 5 is a diagram schematically illustrating an upper limit of a duty ratio with respect to a set rotation speed of the fan motor when performing feedback control of the fan motor.

FIG. 6 is a flowchart showing an outline of control of a blower fan.

FIG. 7 is a flowchart showing an outline of driving of a fan motor.

[Explanation of symbols]

 Reference Signs List 10 air conditioner 12 indoor unit 14 outdoor unit 18 heat exchanger 26 compressor 74 microcomputer 98 microcomputer 110 fan motor 122 blower fan

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Yoshiaki Watanabe 2-5-5 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (72) Yoshinori Nakayama 2-chome Keihanhondori, Moriguchi-shi, Osaka No. 5-5 in Sanyo Electric Co., Ltd.

Claims (2)

[Claims] 1. An air conditioner configured to operate a refrigeration cycle to achieve indoor air conditioning, wherein the number of rotations of a fan motor that blows air to a heat exchanger forming the refrigeration cycle is determined by a change in power supply. Wherein the feedback control is performed such that the fan motor maintains the target rotation speed in a range equal to or less than an upper limit value of electric power set according to the target rotation speed. 2. The air conditioner according to claim 1, wherein the upper limit is further corrected according to an outside air temperature.