JP3136633B2 - Defrost control device - Google Patents

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 performing off-cycle defrost, which relates to a defrost control device capable of performing a defrost operation without causing drain scattering.

[0002]

2. Description of the Related Art Most of air conditioners in a broad sense including a refrigerating device perform defrost operation while blowing a fan of an indoor unit. At the final point of the defrost, drain generated by frost is scattered by the wind. Conventionally, the amount of air is adjusted so as not to cause such a problem, which is a technique known from, for example, Japanese Utility Model Application Laid-Open No. 63-63688.

[0003] This known technique reduces the air volume of a fan of an evaporator at the end of a defrosting operation and at the start of a cooling operation such as at the time of thermo-on so as to prevent water droplets retained in the evaporator fan from scattering. It was made.

[0004]

When the temperature of a refrigerator room or the like is 2 ° C. or higher, the defrost device of the air conditioner stops the compressor and operates the indoor unit fan to reduce the amount of heat held by the indoor air. Off-cycle defrost, which is used as a defrost heat source, is often used.However, since a certain space is required between the evaporator and the drain pan directly below the evaporator, the fan of the indoor unit is particularly an axial fan. If there is, when the fan is rotated at a constant speed during defrost, a part of the wind from the fan passes through the above interval, clogging of the evaporator disappears near the end of defrost, the air volume and the wind speed increase, Since the amount and speed of the wind passing through the space also increase, there is a problem that the drain in the drain pan is scattered, and the surroundings are contaminated. This is particularly problematic when the air flow is increased to reduce the defrost time.

The above-mentioned prior art relates to measures to prevent drain scattering at the end of the defrost operation and at the time of the cooling operation, and there is a problem that drain splash generated during the defrost operation cannot be dealt with at all.

SUMMARY OF THE INVENTION It is an object of the present invention to prevent the scattering of drain water which is likely to occur during the defrost acceleration period when the defrost operation reaches the final stage and the frost is further melted by the frost-melted water, thereby eliminating water wetting. It is to provide a defrost control device.

[0007]

According to the present invention, there is provided an off-cycle type defrost control device for an air conditioner including an indoor unit, wherein the indoor unit is provided with a housing d A drain pan 3 formed by a part thereof is disposed, and an axial fan 4 of an air pushing type is installed on the air inflow side of the evaporator 1, and an initial time of a predetermined defrost operation time T and a predetermined time. A timer circuit 6 for setting a time until the end of the subsequent defrost,
In response to the output of the inverter 7 for changing the rotation speed of the fan 4 and the timer circuit 6, a predetermined defrost operation time T
In the initial time, the air volume of the fan 4 is set to the rated air volume by the inverter 7, and in the time until the end of the defrost thereafter, the air volume of the fan 4 is reduced to a predetermined air volume less than the rated air volume by the inverter 7. After the defrosting, the air flow control processing means 5 for starting the cooling operation at the rated air flow is included. The initial time by the timer circuit 6 is selected in a period before the frost of the evaporator 1 melts and flows down. The defrost control device is characterized in that the time until the end of the defrost is selected as a time when the frost melts and falls as a drain.

The present invention is also directed to an off-cycle type defrost control device for an air conditioner including an indoor unit, which is formed by a part of a housing 2 immediately below an evaporator 1 with a distance d therebetween. A drain pan 3 is disposed, and an axial fan 4 of an air pushing type is installed on the air inflow side from the evaporator 1, and an initial time of a predetermined defrost operation time T and a subsequent defrost end And an inverter 7 for changing the rotation speed of the fan 4. In response to the output of the timer circuit 6, in the initial time of the predetermined defrost operation time T, the inverter 7 The air flow of the fan 4 is set to the rated air flow, and during the time until the end of the defrost thereafter, the fan 4 is stopped by the inverter 7, and after the end of the defrost, Air flow control processing means 5 for starting the cooling operation by the amount, and the initial time by the timer circuit 6 is selected in a period before the frost of the evaporator 1 melts and flows down, and thereafter, the time until the end of the defrost. The time is selected as a time when the frost melts and falls as a drain, and is a defrost control device.

[0009]

According to the present invention, the air flow rate of the fan 4 is reduced or stopped during the defrost operation, so that the drain pan in the drain pan provided immediately below the evaporator of the indoor unit has a large drain pan storage amount. It is possible to reliably prevent carryover from the drain pan due to scattering of water.

[0010] The defrost end time is a time when the frost is melted by the drain generated by the melting of the frost and the defrost speed is remarkably increased. Even if the fan air volume is reduced, the defrost capacity is not so much reduced. No effect on defrost operation.

[0011]

FIG. 1 is a schematic structural view of an indoor unit of an air conditioner according to an embodiment of the present invention.

Immediately below the evaporator 1, a drain pan 3 formed by a part of the housing 2 has a required small interval d.
It is arranged with existence. An axial fan 4 is installed on the air inflow side of the evaporator 1 by an air pushing method.

During the cooling operation of the indoor unit, the indoor air sent by the fan 4 is cooled by the evaporator 1 and is sent to the room as cool air to be cooled.

During the cooling operation, the heat transfer tubes and the fins of the evaporator 1 are frosted and grow gradually, so that defrosting is necessary. The cooling operation is switched to defrosting at predetermined intervals. This defrost is performed by an off-cycle method.

The defrost operation causes the frost to melt and scatter or carry over along the fin portion while flowing down. In addition, when the drain stays in the drain pan 3 due to the influence of the wind pressure and does not flow down from the drain hole, carry-over is performed.

FIG. 2 is a diagram showing the relationship between the defrost operation time and the wind speed I of the fan 4 and the relationship between the amount of drainage II.

The defrost start time when the amount of frost is large is low, the wind speed is small, and the amount of drain generated (amount of frost) is small. As time elapses, the wind speed increases and the amount of drain generated increases, and the amount of drain generated is 10 to 15 minutes of defrost. Of the wind speeds, the wind speed reaches a maximum just before the end, and the wind speed increases in proportion to the passage of time, and a part of the wind speed becomes a state shown by a broken line.

According to the present invention, the carry-over of the drain is prevented by reducing the airflow of the fan 4 including zero before and after the point at which the amount of drainage becomes maximum.

The air volume control means in this case will be described with reference to FIGS. 3 is a block diagram of a control circuit of the air conditioner, FIG. 4 is a time-lapse diagram of the fan 4 over time, and FIG. 5 is a flowchart for explaining the operation of the processing unit shown in FIG.

The processing section 5 has a timer circuit 6 and gives a control command to the inverter 7 to control the rotational speed of the motor of the fan 4 stepwise. The operation of the circuit shown in FIG. 3 is as follows.

In step a1, the cooling operation is stopped and the off-cycle defrost operation is started. At this time, the compressor stops and the fan 4 continues the blowing operation at the rated air volume. The process proceeds to the next step a2, where the timer circuit 6 is operated, and the defrost operation time is compared with the first set time t1 to determine the first set time t1.
When it reaches 1, the flow goes to step a3 to operate the air volume control means, and the fan 4 operates at a low speed via the inverter 7, and reduces the air volume to, for example, １ ／ the rated air volume.

While the fan 4 is operating at a low speed, the time is measured in step a4, and when the second set time t2, ie, the required defrost time, has been reached from the start of defrost, the process proceeds to step a5, where the fan 4 controls the inverter 7 to operate. The operation is switched back to the original rated operation, and the compressor is driven to start the cooling operation, thus ending the defrost operation.

The first set time t1 is, for example, the second set time t1.
It is sufficient to set the time to about half of the set time t2,
FIG. 4 shows the transition of the wind speed of the fan 4.

FIG. 6 shows a fan 4 according to another embodiment of the present invention.
FIG. 7 is a flow chart for explaining the operation of this embodiment. In step b1, the cooling operation is stopped, and the off-cycle defrost operation is started. At this time, the compressor is stopped and the fan 4 continues the blowing operation at the rated air volume. Proceeding to the next step b2, the timer circuit operates to compare the defrost operation time with the first set time t'1,
When the first set time t'1 is reached, the process proceeds to step b3 and the fan 4 stops. While the fan 4 is stopped, time measurement is performed in step b4. When the second set time t2, that is, when the required defrost time has been reached, the process proceeds to step b5, the fan 4 is operated at the original rated air volume, and the compressor is driven. Thus, the cooling operation starts, and the defrost operation ends. It is desirable that the first set time t′1 be set to a timing slightly before the end of the defrost when the frost of the fin portion of the evaporator 1 melts and flows.

As described above, before the end of the defrost, the air volume of the fan 4 can be reduced or the fan 4 can be stopped at a time when the carry-over of the drain is likely to prevent scattering of the drain.

[0026]

As described above, according to the present invention, carry-over and scattering of water droplets can be prevented beforehand by reducing or stopping the air flow of the fan 4 during the operation of the off-cycle defrost. Luggage in the warehouse can be reliably protected from getting wet.

Further, the fan 4 is set to the low speed or the operation is stopped during the middle of the defrosting operation. This time is when the frost is fast and a large amount is performed, and the defrosting time is prolonged. There is almost no effect. In particular, according to the present invention, the initial time set by the timer circuit 6 is a period before the frost of the evaporator 1 melts and flows down. In this period, the air volume of the fan 4 by the inverter 7 is reduced to the rated air volume. This makes it possible to reduce the defrost time, and there is no danger of draining, and the surrounding area is not stained. The time until the end of the defrost operation in the defrost operation time T is the time during which the frost melts and falls as a drain. At this time, the air volume of the fan 4 is reduced below the rated air volume, and is set to zero. It is possible to reduce the length as much as possible and to prevent the scattering of the drain.

[Brief description of the drawings]

FIG. 1 is a schematic structural view of an indoor unit of an air conditioner according to an embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between a defrost operation time, a fan wind speed, and a drain generation amount.

FIG. 3 is a control circuit block diagram of the air conditioner shown in FIG. 1;

FIG. 4 is a graph showing the wind speed over time of a fan.

FIG. 5 is a flowchart illustrating an operation of a processing unit in FIG. 3;

FIG. 6 is a time-lapse diagram of air flow of an indoor unit fan of an air conditioner according to another embodiment of the present invention.

FIG. 7 is a flowchart illustrating a defrost operation of the embodiment shown in FIG. 6;

[Explanation of symbols]

 1 evaporator 4 fan 5 processing unit

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-17582 (JP, A) JP-A-59-229161 (JP, A) Jikken Sho 43-7473 (JP, Y1) (58) Field (Int.Cl. ⁷ , DB name) F25B 47/02 F25D 21/00 F24F 11/02

Claims (2)

(57) [Claims] 1. An off-cycle type defrost control device for an air conditioner including an indoor unit, wherein the indoor unit includes a drain pan 3 formed by a part of a housing 2 immediately below an evaporator 1 with an interval d therebetween. An axial fan 4 of an air pushing type is installed on the air inflow side from the evaporator 1, and an initial time of a predetermined defrost operation time T and a time until the end of defrost after that And an inverter 7 for changing the number of revolutions of the fan 4. In response to the output of the timer circuit 6, at the initial time of the predetermined defrost operation time T, the inverter 7 The air volume is set to the rated air volume, and in the time until the end of the defrosting thereafter, the air volume of the fan 4 is reduced by the inverter 7 to a predetermined air volume less than the rated air volume. And an air volume control processing means 5 for starting a cooling operation at a rated air volume after the end of defrosting. The initial time by the timer circuit 6 is selected in a period before the frost of the evaporator 1 melts and flows down. The time until the end of the defrost is selected as a time when the frost melts and falls as a drain. 2. An off-cycle type defrost control device for an air conditioner including an indoor unit, wherein the indoor unit includes a drain pan 3 formed by a part of a housing 2 immediately below an evaporator 1 with an interval d therebetween. An axial fan 4 of an air pushing type is installed on the air inflow side from the evaporator 1, and an initial time of a predetermined defrost operation time T and a time until the end of defrost after that And an inverter 7 for changing the number of revolutions of the fan 4. In response to the output of the timer circuit 6, at the initial time of the predetermined defrost operation time T, the inverter 7 In the time until the end of the defrost after that, the fan 4 is stopped by the inverter 7, and after the end of the defrost, cooling is performed at the rated air flow. And the air flow control processing means 5 for starting the rotation. The initial time by the timer circuit 6 is selected before the frost of the evaporator 1 melts and flows down, and the time until the end of the defrost is thereafter: A defrost control device, which is selected when the frost melts and falls as a drain.