JP2001255050A - Refrigerator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make variable the timing for starting defrost operation. SOLUTION: In a refrigerator comprising a compressor 20 being driven with variable speed depending on the load, a defrost operation control means 28 for removing frost adhering to an evaporator 11 obtains a timing for starting defrost operation, on condition that total quantity of frost (q), determined by integrating the quantity of frost predicted depending on the rotational speed of the compressor 20 reaches a specified level Q.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerator provided with defrosting operation control means capable of removing frost adhering to an evaporator for generating cool air with good timing.

[0002]

2. Description of the Related Art Conventionally, as a means for controlling defrosting operation in a refrigerator, the operation times of compressors constituting one refrigeration cycle are integrated, and the integrated operation time is a predetermined time (for example, 10 hours).
Time), the defrosting operation is started each time. In such a defrosting operation, for example, the evaporator is heated by melting a frost by controlling a heating means by a heater, and water generated by the defrost is discharged to an evaporating dish in a machine room. You. The water stored in the evaporating dish is evaporated by the heat of the compressor and the condenser in the machine room.

Certainly, the amount of frost formed on the evaporator is correlated with the accumulated time of the compressor, and it is possible to prevent a corresponding defrosting effect, that is, a cooling failure due to so-called frost formation deterioration. However, when the defrosting operation is started only when the operation time of the compressor reaches a predetermined integration time, various conditions may be considered in actual use, for example, the amount of frost on the evaporator may still be small. However, if the defrosting operation is performed while the amount of frost is small, the defrosting operation is not only wasted, but also the cooling operation is performed inefficiently, such as lowering the cooling capacity which was still sufficient. If the defrosting operation is performed after the amount of frost formation becomes considerably large, the cooling operation will be a cooling operation in which cooling failure due to frost formation deterioration has progressed before that, which may affect the food stored in the refrigerator. is there.

In addition, in recent years, in view of the fact that the inside temperature fluctuates due to various factors such as the outside air temperature and the amount of stored food that become loads in actual use, and the frequency of opening and closing the door, the inside of the room at that time is considered. 2. Description of the Related Art Refrigerators using variable-capacity compressors that compare a temperature with a predetermined temperature that has been set in advance and that can change the rotation speed in accordance with the difference (load) have become widespread. In the case of such a configuration, the rotation speed of the cool air fan device with respect to the evaporator is also varied so as to perform the following operation, so that the temperature of the stored food can be quickly and finely controlled by varying the cooling capacity. ing.

[0005]

However, in the case of the above-mentioned structure, the degree of frost on the evaporator also fluctuates depending on the load. That is, in the above configuration, for example, when the internal temperature at that time is high, the rotational speed of the compressor is greatly varied as the load (the difference between the internal temperature and the predetermined temperature) increases, and the cool air fan As the device is also rotated at a high speed, the cooling capacity becomes stronger, and the temperature in the refrigerator is reduced to a predetermined temperature. As a result, the temperature of the evaporator is reduced accordingly, and the heat exchange becomes active due to the increase in the air flow of the cool air fan device, and the amount of frost on the evaporator increases. Therefore, before the next defrosting operation is started, the cooling failure due to the frost formation progresses, and the temperature in the refrigerator eventually increases, and the compressor and the cool air fan device are further rotated at a higher speed. Then, the tendency of frost formation is further promoted and the amount of frost formation increases, and this forms a vicious cycle, and cooling failure proceeds at an accelerated rate. There is a problem that storage at an appropriate temperature cannot be performed stably.

[0006] Such a vicious cycle caused by the fluctuation of the load is further promoted by the opening / closing state of a door for opening / closing a refrigerator or a freezing room as a refrigerator and the temperature of the outside air. When the open time is long or the open time is long, the internal temperature rises naturally, and when the outside air temperature is high, it is inevitable that the heat leak into the internal space becomes large. The fan device had a higher rotation speed, and had a problem that frost formation on the evaporator progressed earlier.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a refrigerator capable of starting a defrosting operation in a timely manner and preventing a cooling failure due to frost formation deterioration. To be.

[0008]

In order to achieve the above object, a refrigerator according to the present invention comprises a compressor driven at a variable speed according to a load, an evaporator for generating cool air, and a blower for blowing the evaporator. A cool air fan device for supplying cool air into the refrigerator, a defrosting unit for removing frost attached to the evaporator, and a defrosting operation control unit for controlling the defrosting unit to perform a defrosting operation. The defrosting operation control means controls the defrosting means on condition that the total frost formation amount obtained by integrating the expected frost formation amount according to the rotation speed of the compressor reaches a predetermined amount. The defrosting operation is started (the invention of claim 1).

According to the above configuration, the amount of frost increases as the compressor rotates at a higher speed. In such a case, the timing of starting the defrosting operation is set earlier.
Therefore, the start time of the defrosting mode can be varied according to the amount of frost that accelerates with respect to the rotational speed of the compressor, and the defrosting can be reliably performed with good timing before cooling deterioration due to frosting occurs. Conversely, when the compressor is rotating at a low speed, the start of the defrost mode is delayed, so if the cooling capacity at the time of the low speed rotation is still sufficient, the cooling capacity can be effectively used,
Such a capacity can be wasted and energy loss due to the defrosting operation can be prevented, and an efficient cooling operation can be performed as a whole.

According to the first aspect of the present invention, the defrosting operation control means includes a priority condition that the continuous operation time of the compressor at a specific rotation speed or more reaches a predetermined time.
The defrosting operation is started (the invention of claim 2).

According to the above configuration, by adding a condition for shifting to the defrosting mode, not only can finer defrosting control be performed, but also if a load increase accompanied by rapid frosting occurs. For example, when cooking food that is still warm or food that is damp is stored in the refrigerator, it depends on whether the cooling capacity at that time is sufficient, that is, whether the high-speed rotation of the compressor is temporary. The transition to the defrosting mode can be controlled depending on whether the operation is continued for a predetermined time or more. Therefore, it is possible to prevent the formation of frost on the evaporator and prevent the cooling operation that causes the cooling failure in the refrigerator.

According to a second aspect of the present invention, the priority condition for starting the defrosting operation is set to different conditions in a plurality of stages (the invention of the third aspect).

According to such a configuration, by adding two different priority conditions, finer defrost control can be performed for the amount of frost that increases in an accelerated manner due to high-speed rotation. When a load fluctuation accompanied by larger and rapid frost formation occurs, it is possible to adjust the timing to quickly and accurately shift to the defrost mode with the high speed rotation of the compressor,
Defrosting can be performed before deterioration of frost formation progresses, and operation due to poor cooling can be eliminated.

[0014] In the first aspect, the defrosting operation control means accumulates the opening times of the doors for opening and closing the inside of the compartment and starts the defrosting operation on a priority condition that a predetermined time has been reached. (Invention of claim 4).

According to such a configuration, the air exchange between the inside and outside of the refrigerator due to the opening and closing of the door can be replaced by the opening time of the door instead of the temperature change having a small fluctuation range, based on the total time obtained by integrating the time. Since the defrosting start timing is obtained, it is possible to shift to the defrosting mode with good timing and certainty, and it is possible to quickly prevent the progress of frosting deterioration due to the open / closed state of the door (opening time).

[0016] In the first aspect, the defrosting operation control means accumulates the number of times the doors that open and close the inside of the refrigerator are opened and starts the defrosting operation on a priority condition that the number of times reaches a predetermined number. The present invention is characterized in that it is configured as described above.

According to this configuration, the defrosting start timing is obtained based on the total number of times the door has been opened (frequency), so that the timing can be surely improved in the same manner as in the invention of the fourth aspect. It is possible to shift to the defrosting mode, and it is possible to promptly prevent the progress of the frost formation deterioration due to the exchange of the air in the refrigerator due to the opening / closing state of the door.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) A first embodiment of the present invention will be described below with reference to FIGS. First, FIG. 2 is a vertical sectional side view showing a schematic configuration of the entire refrigerator. In FIG. 2, the refrigerator main body 1 accommodates a plastic inner box 3 in an iron plate outer box 2, and the outer box 2 and the inner box 3 is filled with a well-known foamable heat insulating material 4. In the refrigerator main body 1, a refrigerator compartment 5, a vegetable refrigerator compartment 6, a first freezer compartment 7, and a second freezer compartment 8 are provided in this order from the upper stage. Refrigeration room 5 at the upper part
The refrigerator compartment 6 is divided into a refrigerator temperature zone, and the first and second freezing compartments 7 and 8 at the lower portion are partitioned into a freezing temperature zone. As the first freezing room 7, for example, an ice making room or a specification switching room is appropriately provided.

As will be described in detail later, the cool air in each temperature zone is generated independently and is not mixed, and the front of each of the chambers 5 to 8 is provided with a door 5a.
To 8a to open and close the so-called interior. However, the doors 6a to 8a of the other chambers 6 to 8 are configured to be able to be pulled out except that the refrigerator compartment 5 is a rotatable door 5a, so that the individually stored food can be easily taken in and out. Is considered.

An evaporator room 10 for refrigeration is formed at the back of the vegetable refrigeration room 6 in the refrigeration temperature zone. The evaporator room 10 includes an evaporator 11 for refrigeration, a cool air fan device 12, A defrost heater 13 as a heat generating means is provided, and the air cooled around by the evaporator 11 is supplied to the cool air duct 1 by the blowing action of the cool air fan device 12.
The circulation of the supply to the refrigeration compartment 5 and the vegetable refrigeration compartment 6 via the refrigeration compartment 4 and then back to the evaporator compartment 10 for refrigeration is repeated. It is configured to be cooled.

On the other hand, an evaporator chamber 15 for freezing is formed at the back of the freezing temperature zone. The evaporator chamber 15 has an evaporator 16 for freezing, a cool air fan device 17, and heat generating means. And the surrounding air cooled by the evaporator 16 is supplied to the first and second freezing chambers 7 and 8 by the blowing action of the cool air fan device 17. After a while, the evaporator chamber 1 for freezing again
5 is repeated, whereby the freezing temperature zones of the first and second freezing chambers 7 and 8 are cooled.

On the other hand, a machine room 19 is provided outside the bottom of the refrigerator body 1. In the machine room 19, FIG.
Are provided with a compressor 20 and a condenser 21 (shown only in FIG. 3) constituting the refrigeration cycle shown in FIG. An evaporating dish 22 is provided above the compressor 20, and a drainage channel connected to each of the cooling chambers 10 and 15 faces the evaporating dish 22. Therefore, the water generated by the defrosting is finally stored in the evaporating dish 22 and evaporated by the heat of the compressor 20 and the condenser 21. Each evaporator 1 for cooling the air circulating in the refrigerator
Since the moisture contained in the air adheres to the first and second frost 16 as defrost, the above-mentioned defrost heaters 13 and 18 are provided as defrost means for forcibly melting the frost. It is provided below 11,16.

In the configuration of the refrigeration cycle shown in FIG. 3, the refrigerant compressed by the compressor 20 flows in the direction indicated by the solid arrow A in FIG. 23. One outlet of the three-way switching valve 23 indicated by a dashed arrow A1 is connected to the inlet side of the refrigeration evaporator 16 via a refrigeration capillary 24, and further connected to a check valve 26 via an accumulator 25. Return to the compressor 20. In addition, three-way switching valve 2
The other outlet indicated by the dashed arrow A2 of 3 is connected to the refrigerating evaporator 11 via a refrigerating capillary 27, and is connected to the inlet side of the compressor 20 in the same manner as described above. Therefore, the configuration in which the refrigerating evaporator 11 and the refrigerating evaporator 16 are connected in parallel to the compressor 20, and the refrigerating evaporator 16 is connected to the refrigerating evaporator 11 via the check valve 26. It is in.

Now, in the above configuration, a state in which the refrigerant flow is switched by the three-way switching valve 23 so that the refrigerant discharged from the compressor 20 flows toward the refrigeration evaporator 11 while the compressor 20 is driven. (Dashed arrow A2 in FIG. 3)
The refrigerant compressed in the compressor 20 is sent to the condenser 21 as a high-temperature and high-pressure gas, where heat is released and liquefied. The liquefied refrigerant flows through the three-way switching valve 23 in the direction of the above-mentioned dashed arrow A2, is sent to the refrigeration evaporator 11 through the refrigeration capillary 27, and deprives the surrounding heat as it evaporates. Cools the surrounding air to produce cool air. The refrigerant gasified by the evaporation then returns to the compressor 20 again, is compressed, and is sent to the condenser 21.

At this time, the cool air cooled by the cooling evaporator 11 is supplied to the refrigerator compartment 5 and the vegetable refrigerator compartment 6 by the blowing action of the cool air fan device 12, and the refrigerator compartment 5, 5
Six refrigeration temperature zones are cooled. In this case, the difference between the temperature of the refrigerator compartment 5, which is the internal temperature, and a predetermined temperature set in advance,
The rotational speed (operating frequency) of the compressor 20 according to the so-called load
Is variably set. Thus, the refrigerant is stored in the evaporator 1 for refrigeration.
The state in which the refrigerator compartment 5 and the vegetable refrigerator compartment 6 are cooled through 1 is called a refrigerator compartment cooling mode.

In a state where the compressor 20 is driven, the refrigerant flow path is switched by the three-way switching valve 23 so that the refrigerant discharged from the compressor 20 flows to the freezing evaporator 16 (see FIG. 3). In the dashed arrow A1), the refrigerant liquefied in the condenser 21 flows through the three-way switching valve 23 in the direction of the dashed arrow A1, passes through the freezing capillary 24, and passes through the freezing evaporator 16.
And evaporates here to remove surrounding heat, and as a result, cools the surrounding air to generate cool air. still,
The gasified refrigerant is stored in the accumulator 25 and the check valve 2.
6 and returns to the compressor 20 again to be compressed.

At this time, the cool air cooled by the refrigerating evaporator 16 is cooled by the cooling air fan device 17 to the first air.
And the second freezing compartments 7 and 8 are cooled, and the first and second freezing compartments 7 and 8 are cooled. In this case, the rotational speed of the compressor 20 (in accordance with the so-called load) is determined according to the difference between the temperature of the first and second freezer compartments 7 and 8 at the time, which is the internal temperature, and a predetermined temperature set. Operating frequency) is variably set. Thus, the three-way switching valve 2
3, a state in which the refrigerant flow path is switched so that the refrigerant discharged from the compressor 20 flows toward the freezing evaporator 16 to cool the first and second freezing chambers 7 and 8 is referred to as a freezing chamber cooling mode. .

In this way, by alternately switching the flowing direction of the refrigerant by the three-way switching valve 26, a so-called ordinary cooling operation for alternately performing the above-described refrigerator compartment cooling mode and freezer compartment cooling mode is performed. . When the first freezing compartment 7 is set as a special-specified compartment, a damper device (not shown) for circulating and shutting off cold air is provided at the cold air inlet side of the first freezing compartment 7, for example. The temperature of the freezer compartment 7 is controlled to a predetermined temperature specification.

The defrosting operation control means of the refrigerator is executed corresponding to the above-described refrigerator compartment cooling mode and freezer compartment cooling mode, respectively. For convenience of description, the defrosting operation for the former refrigerator compartment cooling mode will be described. The control will be described. FIG. 4 is a block diagram showing a schematic control configuration mainly including the defrosting operation control means. In the figure, a control device 28 as a defrosting operation control means is mainly composed of a microcomputer. The control device 28 includes a rotation detection sensor 29 for detecting a frequency corresponding to a rotation speed of the compressor 20, a refrigeration unit. A refrigerator room temperature sensor 30 for detecting a so-called internal temperature in the chamber 5, an external air temperature sensor 31 for detecting an outside temperature, and an evaporator provided in the evaporator chamber 10 and detecting completion of defrosting of the evaporator 11. Temperature sensor 3
2 output signals are provided.

The control device 28 controls the driving of the compressor 20, the three-way switching valve 23, the cool air fan device 12, the defrost heater 13 and the like based on the input signal. In the above, the variable speed drive is performed by inverter control according to the difference (load) between the internal temperature and the preset predetermined temperature, and in some cases, the outside air temperature sensor 31
For example, the operation frequency is driven at a stepwise rotation speed in a range of 30 to 70 Hz, and the cool air fan device 12 is also driven at, for example, 1800 to 24 Hz.
Variable speed drive is performed in the range of 00 rpm. In particular, the control device 28 in this configuration has a function of counting the rotation speed (frequency) of the compressor 20 and reading the operation time corresponding to the rotation speed. Have.

However, the controller 28 drives the compressor 20 and the cool air fan device 12 when the refrigerator compartment temperature sensor 30 detects an on-temperature range of a predetermined temperature during the cooling operation in the refrigerator compartment cooling mode, and FIG. When the cooling operation is started based on the refrigeration cycle indicated by the dashed arrow A2 of FIG.
Stop the operation of No. 2. In this case, the refrigerator compartment temperature sensor 3
The compressor 20 is controlled to rotate at a higher speed as the difference between the internal temperature due to 0 and the on / off temperature (predetermined temperature) increases, and the cool air fan device 12 is also controlled to rotate at a higher speed.

By the drive control of the compressor 20 and the cool air fan device 12, the cooled air is supplied into the refrigerator compartment 5 through the refrigerator evaporator 11 in the refrigerator, and the cooling operation is executed. . In this way, as the cooling operation proceeds, the moisture in the air inside the refrigerator gradually forms frost on the evaporator 11. In this case, as the frost accumulates, the ventilation path around the evaporator 11 is narrowed to reduce the amount of ventilation, and the surface of the evaporator 11 is covered with frost, and the air between the evaporator 11 and the air in the refrigerator is not covered. The heat exchange rate decreases, the temperature of the evaporator 11 itself decreases, and cooling failure due to so-called frost formation deterioration starts to occur.

Moreover, in the case where the compressor 20 is driven at a variable speed according to the load as in the present configuration, the compressor 20 and the cool air fan device 12 rotate at a high speed when the internal temperature increases. As the rotational speed (frequency) of the compressor 20 increases, the temperature of the evaporator 11 further decreases, and the high-speed rotation of the cool air fan device 12 causes heat exchange with a large amount of air in the refrigerator. It is feared that a vicious cycle in which the amount of frost on the surface 11 becomes even greater is repeated.

As described above, as the compressor 20 and the cool air fan device 12 rotate at a high speed, the amount of frost increases, and the cooling failure due to the frost deterioration tends to accelerate. If the door is not completely closed (semi-closed state), such as when the door is not easily detected by a door switch (not shown), such as a gasket gap of a level that cannot be detected by a door switch (not shown). As the load increases, the compressor 20 and the cool air fan device 12 are driven to rotate at high speed, and the time becomes longer.

Therefore, in this embodiment, in order to perform defrosting with good timing, attention is paid to the fact that the timing of defrosting is advanced as the rotational speed of the compressor 20 increases, and the compressor 20
The defrost cycle is shortened when the cooling operation is performed by the high-speed rotation drive, and the defrost cycle is lengthened when the low-speed rotation operation is performed. The relational expression for obtaining the defrost cycle T is as follows. .

[0036]

(Equation 1) FIG. 5 shows the compressor 20 based on the above relational expression (a).
It shows the frost formation amount g (f) with respect to the frequency of, and shows a tendency to increase at an accelerated rate.

Thus, the control device 28 as the defrosting operation control means mainly executes the steps shown in the flowchart of FIG. 1 relating to the defrosting control. First, when the operation is started, the compressor 20 and the cool air fan device 12 are driven at a rotation speed according to a load set based on the refrigerator temperature and a predetermined temperature by the refrigerator compartment temperature sensor 30 which is an output signal of the refrigerator temperature sensor. That is, a so-called normal cooling operation (step P1) is performed. In step P2, the rotation speed of the compressor 20 is constantly monitored by the rotation detection sensor 29 of the compressor 20, and upon receiving the output signal, the control device 28 reads the frequency f (t) and counts the frequency f (t). In step P3, the total amount of frost formation q expected from the above-mentioned relational expression (a) is obtained based on the frequency f (t) as the rotation speed.

In step P4, it is determined whether or not the total amount of frost q is equal to or larger than a predetermined amount, that is, the limit frost amount Q, and "NO" of Q or less (q <Q) is determined. "
In the case of, the operation returns to Step P2 to continue the cooling operation,
If the relationship is equal to or greater than or equal to Q which is “YES” (q ≧ Q), the calculated value of the total frost amount q so far is reset to zero (q = 0) in step P5, and The mode shifts to the defrosting mode shown in P6. Then, the operation in the defrost mode is started. In this embodiment, the defrost operation is performed after the precool operation is performed. That is, first, the compressor 20 is rotated at the maximum allowable rotation speed (for example, 70H) in order to forcibly cool the refrigeration temperature zone.
z), and the cool air fan device 12 is also driven at a high rotation speed (for example, 2400 rpm) and is executed until the temperature of the refrigerating compartment 5 in the refrigerator reaches an off-temperature range of a predetermined temperature. In this case, the precool operation may be controlled by adding a predetermined time.

Subsequently, in this configuration, the defrosting operation using the heat generating means is started. In this defrosting operation, the evaporator 1 is operated with the compressor 20 and the cool air fan device 12 stopped.
1 is performed by energizing the defrost heater 13 located below. Thereby, the evaporator 11 is heated to melt the frost, and the defrost water is evaporated by the heat of the compressor 20, the condenser 21, and the like. Such a defrosting operation is performed by, for example, the evaporator temperature sensor 32 serving as a defrosting sensor in the present configuration.
Is performed until the temperature reaches a predetermined temperature set in advance, at which point the defrost heater 13 is turned off and the process ends.

When the defrosting operation is completed, the process returns to step P1, which is a normal cooling operation pattern, and the cooling operation is efficiently executed under the rotational speed of the compressor 20 according to the load. Then, after the previous defrosting operation is completed, the expected defrosting amount q is newly calculated based on the rotational speed of the compressor 20 counted anew, so that the defrosting operation control means is provided for the subsequent defrosting operation control means. In this embodiment, the limit frost amount Q is set to a predetermined amount. However, the frost amount at a stage where the limit frost amount is slightly larger than the limit amount may be set to the predetermined amount.

As described above, according to the present embodiment, the compressor 20
Is a variable-speed refrigerator having a variable speed so as to exhibit an appropriate cooling capacity according to the load.
Focusing on the fact that the higher the speed of rotation, the greater the amount of frost,
In such a case, the timing for starting the defrosting operation is set earlier. Therefore, as disclosed in FIG. 5, the start timing of the defrost mode (step P <b> 6) can be changed in accordance with the amount of frost that accelerates with respect to the rotation speed (frequency) of the compressor 20. Can be defrosted in a timely manner before the frost formation is deteriorated. On the other hand, when the compressor 20 is rotating at a low speed, the start of the defrosting mode is delayed. Therefore, if the cooling capacity at the time of the low speed rotation is still sufficient, the cooling capacity can be used effectively. Such a capability can be wasted and energy loss due to the defrosting operation can be prevented, and an efficient cooling operation can be performed as a whole.

6 to 10 show the second to fifth embodiments of the present invention, in which the same parts as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted. Only the different parts will be described.

(Second Embodiment) First, FIG. 6 shows a second embodiment of the present invention, in which a condition having a higher priority than the condition for starting the defrosting mode in the first embodiment is added. Thus, the defrost mode is controlled more finely. FIG. 6 is a diagram corresponding to the flowchart shown in FIG. 1 and has a common relationship with the first embodiment except that step R3 is added.

That is, in step R3, the rotational speed (frequency) of the compressor 20 is set to a specific rotational speed αHz (for example, 40H).
z) and the continuous operation time T1 is equal to or longer than the predetermined time T
Only when the vehicle is operated for more than α (for example, 6 hours), this is set as a priority condition, and the basic conditions shown in the following steps R4 and R5 (same as steps P3 and P4 in the first embodiment) are skipped. The mode is shifted to the defrosting mode of R7 to start defrosting.

Therefore, according to the present embodiment, step R7
As conditions for shifting to the defrosting mode of Steps R4 and R
In addition to the original basic conditions based on the expected total frost formation amount q shown in FIG. 5, by adding further different conditions shown in step R3, not only can finer defrost control be performed, Particularly effective countermeasures can be taken, for example, when an increase in the load accompanied by rapid frost formation occurs.

For example, when cooking food that is still warm or food that is wet is stored in the refrigerator, the compressor 2
The rotation speed of 0 increases. Here, if the amount of frost adhering to the refrigeration evaporator 11 is small, the cooling capacity is sufficient,
The rotation speed of the compressor 20 will gradually decrease. However, if the amount of frost is large, the cooling capacity will be reduced, and the rotational speed of the compressor 20 will be further increased to compensate for the insufficient cooling. As a result, the temperature of the evaporator 11 decreases, and the heat exchange due to the increased airflow by the cool air fan device 12 becomes active, and the amount of frost increases to further promote frost formation deterioration. Therefore, in order not to repeat such a vicious cycle, the specific rotation speed αH
When the continuous operation time T1 equal to or more than z reaches the predetermined time Tα (step R3), it is determined that the frost formation on the evaporator 11 is deteriorating, and the mode immediately shifts to the defrost mode (step R6). With this, it is possible to prevent the inside of the refrigerator from being poorly cooled.

(Third Embodiment) FIG. 7 shows a third embodiment of the present invention. Two different conditions are added to one condition for starting the defrosting mode in the first embodiment. Then, the mode can be shifted to the defrosting mode. Incidentally, the flowchart of this embodiment shown in FIG. 7 differs from the flowchart of FIG. 1 of the first embodiment in that two conditions, steps S3 and S4, are added, and the other conditions are common. is there.

That is, first, in step S3 as the first condition, the frequency f, which is the rotational speed of the compressor 20, is set.
As long as (t) is equal to or higher than a specific frequency αHz (for example, 40 Hz) and the continuous operation time T1 is “YES” when the operation is performed for a predetermined time Tα (for example, 6 hours) or more, this is set as a priority condition, and Steps S4, S5 and S
6, the process immediately shifts to the defrosting mode of step R7, and the defrosting operation is started.

Another condition is different from the condition setting described above. Step S3 is "NO" (T1 <T
α), when the process proceeds to the next step S4, the frequency f (t) of the compressor 20 is increased to a specific frequency βHz
(For example, 53 Hz) and its continuous operation time T2
Only when “YES” is operated for a predetermined time Tβ (for example, 4 hours) or more, the next step S5, S6 is skipped, and the process shifts to the defrosting mode of step S8 by setting this as a priority condition. Is to start.
Therefore, if the condition in step S4 is "NO", the process proceeds to the next steps S5 and S6, and the first first
The transition to steps S7 and S8 is controlled based on a comparison between the estimated total frost formation amount q and the predetermined limit frost formation amount Q as in steps P3 and P4 in the embodiment.

As described above, according to the present embodiment, as a condition for shifting to the defrosting mode, the high-speed rotation mode of the compressor 20 is divided into two stages as compared with the first embodiment, and different conditions are set. With the addition of the two priority conditions, a finer defrosting control can be performed for the amount of frost that increases due to the high-speed rotation, and in addition, a load (eg, , A warmer cooked food, or a half-door state), the timing can be adjusted to make the transition to the defrost mode faster with the high-speed rotation of the compressor 20,
As a result, defrosting can be performed before frost formation deterioration progresses, and operation due to poor cooling can be prevented.

Of course, in these steps S3 and S4, if the amount of frost is small with respect to the load, as described in step R3 in the above-described second embodiment, the rotation of the compressor 20 temporarily increased. Speed gradually decreases,
The cooling operation can be effectively performed with the cooling capacity that still has enough power, and there is no unnecessary energy loss. In the present embodiment, the so-called high-speed rotation mode is set to be divided into two stages. However, for example, it may be set to be further subdivided in consideration of the degree of influence or a case that is likely to occur. Even in steps S3 and S4 of the present embodiment, a conditional flow in which these are arranged in reverse may be used if it is suitable for actual use.

(Fourth Embodiment) FIG. 8 is a flowchart showing a fourth embodiment of the present invention. Step W2 is added after the start of the cooling operation (step W1) to FIG. 1 in the first embodiment. The difference is that they are common. That is, in the present embodiment, a function of counting and integrating the opening time of the door 5a is provided.
In this example, the priority condition for shifting to the defrosting mode is set based on the open state of the door 5a. Specifically, the total open time T3 obtained by integrating the open times of the door 5a is within a predetermined time Tw. It is determined whether or not the answer is "YES" within the predetermined time Tw, and the process proceeds to the next step W3 and thereafter, while "NO" when the total opening time T3 has reached or exceeded the predetermined time Tw. In the case of, the process immediately shifts to the defrosting mode of step W7 to execute the defrosting operation.

The reason why the defrosting operation is performed early based on the cumulative opening time T3 of the door 5a will be described below. That is, FIG. 9 shows experimentally obtained fluctuations in the refrigerator interior in the refrigerator compartment 5 by the refrigerator compartment temperature sensor 30 as the refrigerator interior temperature sensor. FIG. 9 (a) shows that the opening time of the door 5a is 10 seconds. (B) and (b) show measured values of the internal temperature of the refrigerator when the refrigerator is opened for 20 seconds. By the way,
In both cases (a) and (b), the temperature fluctuations H1 and H2 in the refrigerator in the open state of the door 5a (without loading a load into the refrigerator) are relatively small changes in which the temperature rises by about 1 degree C. is there. This means that the load does not greatly change with respect to the fluctuations H1 and H2 in the refrigerator temperature, and the compressor 20 does not rotate at high speed. Therefore, this temperature change is directly related to the increase in the amount of frost. It is hard to think there is.

However, it was found that when the door 5a was actually opened and closed in a short time, most of the air in the refrigerator was replaced, and at the same time, moisture in the outside air was also taken into the refrigerator. For this reason, the degree to which frost adheres to the evaporator 11 due to the air having a large amount of water flowing into the refrigerator compartment 5 serving as a refrigerator increases. Therefore, according to the present embodiment, the fluctuation range (H
1, H2) does not depend on a small temperature change, but instead of the opening time of the door 5a, the time is integrated to obtain the total time T3, and the defrosting start timing is obtained in comparison with the predetermined time Tw. In addition, it is possible to reliably shift to the defrosting mode with good timing, and it is possible to quickly prevent the progress of frost formation deterioration due to the open / close state (opening time) of the door 5a.

If the door opening time T3 is less than the predetermined time Tw and "YES" at step W2, the process is the same as that of the first embodiment, that is, the process proceeds to step W3. Based on a comparison between the total frost formation amount q and the limit frost formation amount Q expected in subsequent steps W4 and W5, “YE
In the case of "S", the process shifts to the defrosting mode of step W7 via step W6, and in the case of "NO", the cooling operation is continued by returning between step W1 and step W2, and thereafter, the operation of the door 5a is stopped. If there is an opening / closing operation, an operation such as accumulating the opening time is repeatedly executed.

As described above, in the present embodiment, the timing of starting the defrosting mode is varied based on the rotation speed of the compressor 20 in each of the above embodiments. In view of the fact that no significant temperature change is observed, it is added that the defrosting start timing can be varied by setting the integrated opening time T3 as a priority condition.
Thereby, based on the opening time T3 of the door 5a which is completely different from each of the above embodiments, it is possible to cope with an increase in frost due to replacement of the air in the refrigerator, and to compare the temperature in the refrigerator with a small fluctuation width. The defrosting start timing can be accurately obtained. It is to be noted that the exchange of the air in the refrigerator as in this embodiment is greatly affected by the outside air temperature (heat leak), and therefore, for example, the temperature detected by the outside air temperature sensor 31 (shown only in FIG. 4). Is higher than a predetermined temperature, it is possible to control and set so that the timing of the start of defrosting is further advanced.

(Fifth Embodiment) FIG. 10 is a flow chart showing a fifth embodiment of the present invention. Step X2 is added to FIG. 1 in the first embodiment after the start of the cooling operation (step X1). In this respect, the other steps are common, and in particular, the flow is the same as the fourth embodiment except that step W2 is replaced by step X2.

That is, in this embodiment, the priority condition for shifting to the defrosting mode is set based on the open / closed state of the door 5a. More specifically, a function of counting the number of times the door 5a is opened and integrating it is provided. The defrosting mode start timing can be varied by giving priority to whether or not the total number of times of opening N1 obtained by integrating the number of times of opening of the door 5a is within a predetermined number of times Nx. Things.

Therefore, in this step X2, when the number of times of opening N1 has reached or exceeded the predetermined number of times Nx (N1 ≧ Nx), that is, in the case of “NO”, the process immediately shifts to the defrosting mode of step X7. The defrosting operation is performed. The other operations are common except for the difference between the opening time T3 and the number of times of opening N1 in the fourth embodiment, and a description thereof will be omitted.

As described above, in the present embodiment, the fourth
Similar to the embodiment, in view of the fact that the inside temperature does not change so much when the door 5a is opened and closed (see FIG. 9),
The addition of the fact that the defrosting start timing can be varied by setting the accumulated number of times N1 of opening the door 5a as a priority condition. Thereby, it is possible to cope with an increase in frost formation due to replacement of air due to opening and closing of the door 5a, and it is possible to accurately obtain a timing for starting defrosting.

Although the defrosting operation control means has been described in connection with the refrigerator compartment temperature zone, it goes without saying that the same specifications can be applied to the freezer compartment temperature zone and other freezing and refrigerating compartments. In each of the above embodiments,
As the defrosting mode, the precooling operation was also performed immediately before the defrosting operation by the defrosting heater, but this may be appropriately selected and adopted, and the defrosting means is used for the defrosting operation by the defrosting heater. The present invention is not limited to the embodiments described above and shown in the drawings. For example, the defrosting unit may be implemented by cycle defrosting. Various modifications may be made without departing from the scope of the present invention. You can do it.

[0062]

As is apparent from the above description, the present invention relates to a defrosting operation control means for a refrigerator having a compressor driven at a variable speed, wherein the rotation speed of the compressor increases as the rotation speed increases. Focusing on increasing the amount of frost adhering to the evaporator,
On the condition that the total frost amount obtained by integrating the expected frost amount according to the rotation speed of the compressor has reached a predetermined amount, a timing of starting the defrost mode by the defrost means is obtained. It was done.

According to this, the timing of the start of the defrosting mode can be varied according to the rotational speed of the compressor. More specifically, the timing of the start of the defrosting is advanced as the rotation speed increases, and conversely, the defrosting cycle at the low rotation speed. Can be extended, and an accurate defrosting operation suitable for practical use can be performed. Therefore, the operation is not performed due to the cooling operation being executed due to a cooling failure in which the defrosting mode is advanced due to a delay in shifting to the defrosting mode even if the cooling capability is still sufficient or the shift to the defrosting mode is delayed. A refrigerator that can be used can be provided.

[Brief description of the drawings]

FIG. 1 is a flowchart mainly showing defrost control according to a first embodiment of the present invention.

FIG. 2 is a vertical sectional side view showing a schematic configuration of a refrigerator.

FIG. 3 is a configuration diagram of a refrigeration cycle.

FIG. 4 is a block diagram of an electric configuration mainly for defrost control;

FIG. 5 is a characteristic diagram of the amount of frost per unit time.

FIG. 6 is a view corresponding to FIG. 1, showing a second embodiment of the present invention.

FIG. 7 is a view corresponding to FIG. 1 showing a third embodiment of the present invention.

FIG. 8 is a view corresponding to FIG. 1, showing a fourth embodiment of the present invention;

FIG. 9 is a data characteristic diagram of the temperature in the refrigerator due to opening and closing of the door

FIG. 10 is a view corresponding to FIG. 1, showing a fifth embodiment of the present invention.

[Explanation of symbols]

5 is a refrigerator room, 5a is a door, 6 is a vegetable refrigerator room (refrigerator room), 7
Denotes a first freezing room (freezing room), 8 denotes a second freezing room (freezing room), 11 and 16 denote evaporators, 12 and 17 denote cool air fan devices, and 13 and 18 defrost heaters (defrost means). , 20 is a compressor, and 28 is a control device (defrosting operation control means).

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3L046 AA02 BA01 FB06 GA01 GA06 GB01 JA11 KA00 KA02 KA05 LA16 LA22 MA01 MA02 MA03 MA04 MA05

Claims (5)

[Claims] A compressor driven at a variable speed according to a load;
Controlling the evaporator that generates cool air, a cool air fan device that blows the evaporator to supply cool air into the refrigerator, a defrost unit for removing frost attached to the evaporator, and the defrost unit Defrosting operation control means for performing a defrosting operation, the defrosting operation control means, the total frost amount obtained by integrating the expected frost amount according to the rotation speed of the compressor to a predetermined amount A refrigerator wherein the defrosting means is controlled to start a defrosting operation on condition that the temperature has been reached. 2. The defrosting operation control means is configured to start a defrosting operation on a priority condition that a continuous operation time at a specific rotation speed or higher by a compressor has reached a predetermined time. The refrigerator according to claim 1, wherein 3. The refrigerator according to claim 2, wherein the priority condition for starting the defrosting operation is set to different conditions in a plurality of stages. 4. The defrosting operation control means accumulates the opening times of the doors for opening and closing the inside of the refrigerator and starts the defrosting operation on a priority condition that a predetermined time has been reached. Item 7. The refrigerator according to Item 1. 5. The defrosting operation control means accumulates the number of times of opening of a door that opens and closes the inside of the refrigerator and starts the defrosting operation on a priority condition that the number of times reaches a predetermined number. Item 7. The refrigerator according to Item 1.