JP2001215077A - Defrost controller, method for controlling and refrigerator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem of not defrost of an evaporator due to a decrease in a cooling efficiency of the evaporator by frosting when frosted according to an integrated time of a compressor and a wasteful power consumption due to a defrosting operation for a predetermined time even by a small frost. SOLUTION: Temperature detectors of two systems are mounted at the evaporator, and the defrosting operation is controlled by judging an actually frosted state according to their temperature difference. The lapse of a predetermined cooling time is confirmed (S2) during the operation of the compressor (S1). When the temperature difference of the two systems is a predetermined value or less or a predetermined defrosting period interval or more by judging the difference (S3), a power supply to the defrosting heater 7 is started (S4). Then, a set temperature or higher of the evaporator is confirmed by a sensor (S5). The power supply to the heater 7 is finished (S6), and the operation is returned to the cooling operation. Since the defrosting control is conducted by the actually frosted state of the evaporator, wasteful power consumption can be reduced, and a sound indoor temperature management can be conducted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a defrost control device and control method and a refrigerator, and more particularly to a control of a defrost interval suitable for a refrigeration system requiring a defrost function such as a refrigerator.

[0002]

2. Description of the Related Art Conventionally, in a refrigerator or the like, when a compressor and a fan motor operate, cool air in a refrigerator is circulated,
Water vapor and the like contained in the cool air eventually become frost and gradually adhere to the evaporator.

[0003] In a refrigerator to which frost adheres as described above, the amount of frost formation tends to increase depending on the amount of cooling load and the number of times the door is opened and closed. There is a problem that the heat exchange efficiency decreases.

[0004] Therefore, generally, the operating time of the compressor is accumulated, and when the accumulated time reaches a predetermined time (for example, 8 hours), the defrost heater is energized to heat the evaporator. Then, frost adhering to the evaporator is removed.

After that, when the evaporator temperature sensor reaches a predetermined defrost end temperature, usually a set temperature at which all the frost adhering to the evaporator is considered to have been completely melted, the energization of the defrost heater is terminated, It returns to the normal cooling operation.

In the control operation of the defrosting interval, after the defrosting is completed, the normal operation is first started, and it is determined whether or not the cumulative operation time of the compressor has reached a predetermined set time. Therefore, when the set time has been reached, it is determined that frost has sufficiently adhered to the evaporator, and the operation proceeds to the defrosting operation. JP-A-60-30975 discloses an example related to this type of control method.

[0007]

In the above prior art, whether the operation of the compressor is low or high,
Also, regardless of whether the door is opened or closed, the defrosting operation is started when the cumulative operation time of the compressor reaches a predetermined set time.

However, for example, when the rotation speed of the compressor is variable by the inverter device, the fact that the compressor is operating at a low rotation speed generally means that the compressor is operated under a light load (outside air, low temperature and low humidity, low food in the refrigerator, door in the refrigerator, etc.). (The number of times of opening / closing is small), and the progress rate of frost formation on the evaporator is relatively slow.

On the other hand, when the compressor is operating at a high rotation speed, it means that the compressor is under a high load (high temperature and humidity of the outside air, many foods in the refrigerator, many times of door opening / closing), and the cooling air circulating in the refrigerator is high. The amount of water increases, and the speed of frost formation on the evaporator is high.

Therefore, if the compressor operation integration time is set to be short, when the compressor is operating at a high rotation speed,
When the number of times of opening and closing the door is large, the appropriate defrost interval is set.However, when the compressor is operating at a low rotation speed or when the number of times of opening and closing the door is small, the amount of frost is small and it is necessary to still perform defrosting. Without the need to use defrost, waste power,
Problems arise such as an adverse effect on the preserved food due to an increase in the temperature in the refrigerator.

[0011] When the accumulated operation time of the compressor is set to be longer, an appropriate defrosting interval is obtained when the compressor is operating at a low rotation speed or when the number of times of opening and closing the door is small. When operating at a rotational speed or when the number of times of opening and closing the door is large, defrosting does not start even though the amount of frost is large, so the heat exchange rate between the evaporator and the circulating cold air in the refrigerator decreases, and the Problems such as an adverse effect on stored food due to a rise in temperature and an increase in power consumption due to insufficient cooling occur.

SUMMARY OF THE INVENTION An object of the present invention is to solve the problems of the prior art described above. By performing defrosting of an evaporator at an optimum time, it is possible to store food in a refrigeration system such as a refrigerator. To reduce the power consumption.

[0013]

SUMMARY OF THE INVENTION The object of the present invention is to provide a frost detecting means for detecting frost adhering to an evaporator of a refrigeration cycle, a defrosting means for removing frost adhering to an evaporator, and a frost detecting means. This is achieved by a defrost control device that includes a defrost control unit that controls the operation of the defrost unit based on a signal. According to the present invention, it is possible to control the defrosting operation based on the actual amount of frost formed on the evaporator.

The present invention is applied to a refrigerating cycle of a refrigerator or the like, and detects a frost formation state of an evaporator based on a temperature difference between an evaporator body temperature and a cool air temperature around the evaporator. For example, a first system for detecting the temperature of the evaporator itself and a second system for detecting the temperature of cool air around the evaporator are provided as frost detection means.
By installing a temperature detection element consisting of
The frost formation state can be determined from the temperature difference between the detected temperatures of the two systems. In addition, by appropriately arranging a plurality of frost detection means, fine defrost control can be performed.

According to the control method of the present invention, when the temperature difference between the evaporator main body and the periphery of the evaporator becomes equal to or less than a predetermined value, defrosting of frost adhering to the evaporator is started. Of course, when the operation of the refrigeration cycle including the evaporator has elapsed for a predetermined time, or when the evaporator has a temperature equal to or lower than a predetermined temperature, or when the temperature difference is equal to or higher than a predetermined value, the predetermined defrost cycle time elapses. Then, the defrosting operation may be started.

Further, according to the present invention, the defrosting of the evaporator is terminated when the temperature of the evaporator body or the temperature around the evaporator reaches a predetermined value, so that the evaporator is efficient and wasteful. Defrosting operation can be controlled.

Still another object of the present invention is to provide, in addition to a refrigerator equipped with the above-described defrost control device, a compressor which is operated until the next defrost is started based on the operating speed of the compressor and the number of times the door is opened and closed. This is also achieved by a refrigerator provided with a control unit that changes the integrated operation time.

That is, the operating speed of the compressor is detected every predetermined time after the completion of defrosting, and a predetermined weighting coefficient value is integrated for each operating speed, and the integrated value reaches a predetermined value. Sometimes, by providing the control unit that starts the next defrost, an efficient defrost operation based on various past data can be performed.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. First, an example of a refrigerator equipped with the defrost control device of the present invention will be described. FIG. 7 is a longitudinal sectional view of the present embodiment. The refrigerator main body 1 has a freezer compartment 2 and a refrigerator compartment 3, and further includes a compressor 4 and an evaporator 5.

The freezing compartment 2 is provided with an evaporator temperature detecting sensor 6 for detecting a temperature near the evaporator 5 and a defrost heater 7 provided near the evaporator for removing frost adhering to the evaporator 5. In addition, a cool air circulation fan 8 for circulating cool air in the refrigerator and a fan motor 9 for driving the cool air circulation fan in the refrigerator are provided.

The evaporator 5 is provided with a frost detector 11 for judging the state of frost based on the temperatures detected by the two temperature detecting elements. This frost detector 11 is mounted on the cooling pipe 5a of the evaporator 5, as shown in FIG. Further, a control device 20 for controlling a cooling operation, a defrosting operation, and the like based on information of the frost formation detector 11 is provided.

As shown in FIG. 5, the frost detector 11 has two temperature detecting elements 11a and 11b. One temperature detecting element 11b detects the temperature Tc of the evaporator 5 itself and the other temperature detecting element 11b. The temperature detecting element 11a detects a cool air temperature Td around the evaporator 5.

Here, the cool air temperature Td around the evaporator 5 is:
Because it detects cold air that has been heat exchanged with the air in the refrigerator,
Usually, the temperature is higher than the temperature Tc of the evaporator 5 itself. That is, when the compressor 4 and the fan motor 9 are driven and the frost formation on the evaporator 5 is small, the temperature difference (Td-Tc) between the detected temperatures of the two systems of the frost formation detector 11 increases.

Conversely, when the evaporator 5 has a lot of frost, the temperature detecting element 11a is blocked by the frost.
This means that the temperature of a is detected, and the same temperature as that of the temperature detecting element 11b is detected. Therefore, the temperature difference (Td-Tc) between the detected temperatures of the two systems of the frost detector 11 becomes smaller.

In the refrigerator having the above-described structure, when the compressor 4 and the fan motor 9 are operated, cool air in the refrigerator is circulated, but the water in the cool air eventually becomes frost and evaporator. 5 gradually adheres.

In the present embodiment, the amount of frost on the evaporator 5 varies depending on the amount of internal load, the number of times the door is opened and closed, and the like.
If the accumulated operation time of the vehicle reaches a predetermined value,
When it is determined that defrosting is necessary, the operation of the compressor 4 and the fan motor 9 is stopped, the defrosting heater 7 is energized to heat the evaporator 5, and the frost adhering to the evaporator 5 is removed.

Thereafter, when the evaporator temperature detecting sensor 6 reaches a predetermined defrost end temperature (set to a temperature at which all the frost adhering to the evaporator 5 is considered to have been melted), the defrost heater 7 is turned on. Is terminated, and the operation returns to the normal cooling operation.

Here, the frost detector 11 is attached to a portion where the cool air that has cooled the inside of the refrigerator returns to the evaporator 5, that is, to a return cool air inlet portion of the evaporator 5. This is because the frost easily adheres to the return cold air inlet of the evaporator 5 where the high temperature and high humidity return cold air comes first.

Hereinafter, an example of the defrosting control operation of the refrigerator according to the present invention will be described with reference to the flowchart of FIG. First, the cooling operation of the compressor is checked in step S1, and whether a predetermined time has elapsed after the compressor 4 and the fan motor 9 are driven is checked in step S2.

After confirming that a predetermined time has elapsed in step S2, a temperature difference between the detected temperatures of the two systems of the frost detector 11 is determined in step S3, and when the temperature difference becomes equal to or less than a predetermined value, or in advance. If it is equal to or longer than the set defrost cycle interval (for example, the cumulative operation time of the compressor 4), the process proceeds to the next step 4.

In step S4, the operation of the compressor 4 and the fan motor 9 is stopped, and the power supply to the defrost heater 7 is started. Here, the reason why the defrosting is started not only based on the temperature difference of the frost formation detector 11 but also with time is to prevent malfunction due to erroneous determination of the frost formation detector 11.

Next, in step S5, the evaporator temperature detection sensor 6 monitors whether or not the frost adhering to the evaporator 5 has reached a set temperature at which it is considered that all the frost has been completely melted. If the temperature has become equal to or higher than the set temperature, the process proceeds to step S6, in which the power supply to the defrost heater 7 is terminated, and the operation returns to the normal cooling operation.

In the control of the above defrosting operation, for example,
It is of course possible to perform the defrosting operation only by determining the actual amount of frost formed on the evaporator 5 by the frost detector 11 without setting the defrost cycle interval based on the accumulated operation time of the compressor.

FIG. 2 is a flowchart showing another example of the defrost control operation according to the present invention. In this example, in the refrigerator shown in FIG.
Are installed in two or more sets. This is, for example, one by one mounted on each of the left and right sides of the evaporator 5, so that even if the frost distribution of the evaporator 5 is biased, it is possible to reliably determine that frost is formed.

As shown in FIG. 2, during the cooling operation (step S11), it is confirmed that a predetermined time has elapsed after the compressor 4 and the fan motor 9 have been driven (step S12). The temperature difference between the detected temperatures of the two or more pairs of systems is determined (step S13).

Any one of the two or more sets of temperature differences
If at least one falls below the predetermined value, the operation of the compressor 4 and the fan motor 9 is stopped, and the energization of the defrost heater 7 is started (step S14).

Next, it is monitored whether or not the evaporator temperature detecting sensor 6 has reached a predetermined temperature or higher (step S1).
5). Then, when the temperature becomes equal to or higher than the predetermined temperature, the power supply to the defrost heater 7 is terminated (step S16), and the operation returns to the normal cooling operation.

After the start of defrosting, the frost formation detector 11
When one or both of the detection temperatures of the system reach a predetermined temperature or higher at which it is considered that all the frost attached to the evaporator 5 has been completely melted, the power supply to the defrost heater 7 is terminated, If control is performed so as to return to the normal cooling operation, the function of the evaporator temperature detection sensor 6 is also achieved, so that the conventionally used evaporator temperature detection sensor 6 can be omitted.

In the above control, the temperature difference between the two temperature detecting elements is measured after a predetermined time (5 minutes) in step S2 of FIG. 1 and step S12 of FIG. This is because a predetermined time is required after the cooling operation until the evaporator 5 is sufficiently cooled.

Here, the elapse of the time is waited, and this wait time is related to the entire apparatus and varies depending on the outside air temperature. Therefore, it is desirable to adjust the wait time during operation according to these conditions.

FIGS. 3 and 4 are flowcharts each showing still another example of the defrosting control operation in the present invention. FIG. 3 shows a case where the frost detector 11 is one set.
The case of two or more sets is shown in FIG.

The difference between these control examples from the examples of FIGS. 1 and 2 is that in the above-described example, the control is performed in step S2 or S3.
As described above, the predetermined waiting time is set, but in this example, the temperature change of the evaporator is measured instead of setting the waiting time.

That is, as shown in FIGS. 3 and 4,
In steps S22 and S32, instead of waiting for a predetermined time, the temperature of the evaporator is reduced to a predetermined temperature or less by using the evaporator temperature detection sensor 6 and the temperature detection element 11b installed in the evaporator 5, and To move to the next step.

The predetermined temperature in step S22 or S32 may be determined depending on the refrigeration cycle, but may be set to about minus 25 ° C. in a home refrigerator. The other steps are the same as those in the example of FIG. 1 or FIG.

Here, the temperature detection state of the frost formation detector having two temperature detection elements according to the principle of the present invention will be described. FIG. 6 shows the temperature change of the frost detector during the operation and the stop of the compressor.

When the temperature detecting element shown in FIG. 5 is arranged in the cooling pipe of the evaporator, as shown in FIG. 6, when the amount of frost is small, the evaporator main body (temperature detecting element 11a) and its vicinity are provided. (Temperature detecting element 11b) has a temperature difference as shown on the left side in the figure. Conversely, when there is a temperature difference, it can be determined that the amount of frost is small.

When frost adheres to the temperature detecting elements 11a and 11b, there is almost no difference between the detected temperatures of the two as shown in the right side of the figure. That is, when the temperature difference between the two systems disappears, it can be determined that the amount of frost is large.

According to the above-described embodiment, defrosting is executed by determining the actual state of frost formation on the evaporator, so that useless defrosting operation can be prevented, so that power consumption is reduced and wasteful defrosting is performed. Since the evaporator is not heated, the internal temperature does not rise too much.

Next, an example of controlling the defrosting of the refrigerator based on the cumulative operation time of the compressor will be described with reference to FIGS. The same components as those in the embodiment shown in FIG. 7 are denoted by the same reference numerals.

In FIG. 9, when the compressor 4 and the fan motor 9 are operated, the cool air in the refrigerator is circulated, and the water in the cool air eventually becomes frost and gradually adheres to the evaporator 5. . At this time, the amount of frost on the evaporator 5 changes depending on the amount of internal load, the number of times the door is opened and closed, and the like.

In this example, when the accumulated operation time of the compressor 4 reaches a predetermined value, the operation of the compressor 4 and the fan motor 9 is stopped, the defrost heater 7 is energized, and the evaporator 5 is heated.
The frost adhering to the evaporator 5 is removed.

Thereafter, when the evaporator temperature detection sensor 6 reaches a predetermined defrost end temperature at which it is considered that all the frost attached to the evaporator 5 has been completely melted, the energization of the defrost heater 7 is terminated. The operation returns to the cooling operation.

FIG. 8 is a flowchart showing the above defrosting control operation. During the cooling operation, first, it is determined whether or not the cumulative operation time of the compressor has reached a predetermined time (step S41).

Next, if the predetermined time has been reached,
Power supply to the defrost heater 7 is started (step S42).
Then, it is determined whether or not the evaporator temperature detection sensor 6 has reached a predetermined temperature (step S43).

Then, if the predetermined temperature has been reached,
It is determined that the evaporator 5 has been sufficiently heated, and that all the frost attached to the evaporator has been melted, and the energization of the defrost heater is terminated (step S44). Thus, the defrosting operation is completed, and the operation returns to the normal operation.

The amount of frost generated around the evaporator varies depending on the outside air temperature and humidity, the temperature around the evaporator, and in the case of a refrigerator, the amount of food stored in the refrigerator. Therefore, if defrosting is performed at a constant time cycle regardless of the amount of frost, the defrost will be performed even if the amount of frost is small.

Conversely, there is a case where the defrosting is not performed unless the predetermined defrost cycle time is reached even though the amount of frost is large. In such a case, the evaporator is cooled by the frost. Since the efficiency is reduced, there is a possibility that the internal temperature increases.

Therefore, according to the above-described defrost control device of the present invention, since the cooling and defrosting operations are controlled based on the actual amount of frost, such problems are prevented, and efficient operation is achieved. As a result, power consumption can be reduced and a healthy internal temperature can be maintained.

Next, another embodiment of the refrigerator which achieves the object of the present invention will be described with reference to FIGS. FIG. 10 is a flowchart illustrating an example of a defrost interval control method according to the present embodiment, and FIG. 11 is a longitudinal sectional view of the refrigerator according to the present embodiment.

The refrigerator main body 51 of this embodiment has a freezer compartment 52 and a refrigeration compartment 53, and the compressor 54 has a variable power supply frequency made variable by an inverter device to make the operating speed variable. For example, 2400, 3000, 3
Operate at 600 rpm.

An evaporator temperature sensor 56 for detecting the temperature is provided in the vicinity of the evaporator 55 for cooling the inside of the refrigerator, and a defrost heater 57 is provided near the evaporator in order to remove frost attached to the evaporator 55. Further, a cooling fan 58 for circulating cool air in the refrigerator, a fan motor 59 for driving the cooling fan 58 in the refrigerator, and the like are provided.

Further, the controller 70 mainly composed of a microcomputer counts the number of times the door is opened and closed based on the accumulated operation time of the compressor and the input from the door switch 71. Based on the information, the cooling operation and the defrosting operation are performed. And so on.

Also in the refrigerator of this embodiment, when the compressor 54 and the fan motor 59 are operated, the cool air in the refrigerator is circulated, and the steam and the like contained in the cool air eventually become frost and become the evaporator 5.
At this time, the frost formation amount tends to increase due to the amount of the cooling load and the number of times the door is opened and closed. The efficiency decreases as in the other examples described above.

In the present embodiment, the defrost interval is determined according to the defrost interval control method described below, the evaporator 55 is heated by the defrost heater 57 to remove the attached frost, and then the evaporator temperature sensor 56 Accordingly, a predetermined defrost end temperature at which it is considered that all the frost attached to the evaporator 55 has been completely melted is detected, the energization of the defrost heater 57 is terminated, and the operation returns to the normal cooling operation.

FIG. 10 is a flowchart showing an example of a defrosting interval control method of the refrigerator. The initial value of the weighting coefficient integrated value T is set to 0 (step S51), and then it is determined whether or not the detection setting time of the weighting coefficient value (for example, detection is performed every minute) has been reached (step S51). S52).
Then, if the detection set time has been reached, proceed to the next step. It is determined whether a door opening / closing operation has been performed since the start of the previous defrosting operation (step S53).

If the door opening / closing operation has been performed since the start of the previous defrosting operation, the compressor speed is set to 0 in steps S54, S56, S58, and S60.
(Stop) It is determined whether the rotation is 2400, 3000, or 3600 rpm, and the value of the predetermined weighting coefficient K is selected from 0, 75, 100, and 125.

Here, the weighting coefficient value K is set to a larger value as the rotational speed of the compressor is higher. Next, [weighted coefficient integrated value T + weighted coefficient value K] is performed, and the weighted coefficient integrated value T is calculated again (step S7).
0).

Next, it is determined whether or not the value of T has reached a predetermined value (for example, 60000 or more) (step S71). If it has reached, the defrosting operation is started in step S72, and if not, the process returns to step S2.

If the door opening / closing operation has not been performed since the start of the previous defrosting operation, step S12, step S1
4. In steps S16 and S18, the compressor rotation speed is 0 (stop), 2400, 3000, and 3600, respectively.
It is determined whether the rotation / minute or not, and the value of the predetermined weighting coefficient value K is selected from 0, 25, 75, and 100.

Here, the weighting coefficient value K is set to a larger value as the rotation speed is higher, as in the case where the door is opened and closed. K is set to a smaller value when no door opening / closing operation is continued than when there is an error.

Next, the process proceeds to step S20, where [weighted coefficient integrated value T + weighted coefficient value K] is performed, and the weighted coefficient integrated value T is calculated again. Next, the process proceeds to step S21 to determine whether the value of T has reached a predetermined value (for example, 60000 or more).

If it has reached, the process proceeds to step S22 to start the defrosting operation. If not, the process returns to step S2.
When the defrosting operation is started, the process returns to the start, and the same processing is repeated.

With such a control method, the time required to reach a predetermined weighting coefficient integrated value in accordance with the operating speed of the compressor and the presence / absence of the door opening / closing operation increases the operating speed of the compressor. When there is a door opening / closing operation at a short time, for example, when the door opening / closing operation is performed halfway and the operation is continuously performed at 3600 rpm, the accumulated operation time of the compressor is 8 hours.
Perform defrosting operation in time.

Further, when the operation speed of the compressor is low or when there is no door opening / closing operation, the operation time of the compressor is long, for example, when there is no door opening / closing operation and the operation is continued at 2400 rpm. The defrosting operation is performed for 40 hours.
Further, if the operating speed of the compressor changes, the defrosting operation can be performed in an intermediate integrated time, so that the defrosting operation can be performed in an appropriate time.

Although the operating speed of the compressor of this embodiment is an example of three stages of 2400, 3000 and 3600 revolutions / minute, when the number of stages of the variable speed is increased, the weight is accordingly adjusted. What is necessary is just to set the coefficient value K finely.

In this embodiment, as shown in FIG. 10, whether the door opening / closing operation has been performed since the previous start of the defrosting operation is determined.
Alternatively, the weighting coefficient value K is given only depending on whether the door opening / closing operation has been performed once or twice or N.
If the determination is made in step S3 in the figure and different weighting coefficient values K are given, finer defrost interval control can be performed.

According to the refrigerator of the present embodiment, when the operating speed of the compressor is high or when the door is opened / closed, that is, when the speed of frost formation on the evaporator is high, the defrost interval is shortened. When the operating speed of the compressor is low or when there is no door opening / closing operation, that is, when the frost formation speed on the evaporator is low, the defrosting control system that controls the defrosting interval longer is provided. This has the effect of providing the customer with a refrigerator that does not have the problem of consuming wasteful power by performing the defrosting operation or the problem of adversely affecting the stored food due to an increase in the internal temperature.

The present invention is not limited to the above-described embodiments. The defrost control device or method of the present invention described with reference to FIGS. 5 and 6 described above is combined with the defrost control method of the present invention described with reference to FIGS. It is also possible to do.

[0079]

As described above, according to the present invention,
In a refrigeration cycle such as a refrigerator, the defrosting operation is performed based on the actual state of frost on the evaporator, or based on the number of rotations of the compressor and the number of door opening / closing operations. Can be implemented efficiently, prevent adverse effects on preserved foods,
In addition, power consumption can be reduced.

[Brief description of the drawings]

FIG. 1 is a flowchart illustrating an example of a defrost control method according to the present invention.

FIG. 2 is a flowchart illustrating another example of the defrosting control method of the present invention.

FIG. 3 is a flowchart illustrating yet another example of the defrost control method of the present invention.

FIG. 4 is a flowchart illustrating yet another example of the defrost control method of the present invention.

FIG. 5 is a diagram showing an example of mounting a frost detector of the defrost control device of the present invention.

FIG. 6 is a diagram illustrating a temperature change of the frost detector during operation and stop of the compressor according to the present invention.

FIG. 7 is a schematic longitudinal sectional view showing an example of a refrigerator equipped with the defrost control device of the present invention.

FIG. 8 is a flowchart illustrating an example of defrost control of the refrigerator based on the cumulative operation time of the compressor.

FIG. 9 is a schematic longitudinal sectional view of the refrigerator described in FIG.

FIG. 10 is a flowchart illustrating a defrosting interval control method for a refrigerator according to the present invention.

FIG. 11 is a schematic sectional side view of the refrigerator described in FIG. 10;

[Explanation of symbols]

 1,51 Refrigerator body 2,52 Freezer compartment 3,53 Refrigerator compartment 4,54 Compressor 5,55 Evaporator 5a Cooling pipe 6,56 Evaporator temperature detection sensor 7,57 Defrost heater 8,58 For cold air circulation in the compartment Fan 9, 59 Fan motor 10, 20, 60, 70 Control device 11 Frost detector 11a, 11b Temperature detecting element 71 Door switch

Continued on the front page (72) Inventor Tohru Kobayashi 800, Tomita, Ohira-machi, Shimotsuga-gun, Tochigi Prefecture Inside the Cooling Division, Hitachi, Ltd. Within business division (72) Inventor Shoichi Kano 800, Tomita, Oda-machi, Ohira-machi, Shimotsuga-gun, Tochigi Prefecture Within the cooling division of Hitachi, Ltd. (72) Inventor Koichi Shibata 800, Tomita, Odai-machi, Ohira-machi, Shimotsuga-gun, Tochigi Prefecture Within the Cooling and Refrigerating Business Dept., Hitachi, Ltd. F term (reference) 3L046 AA02 BA01 CA06 FB02 GA03 GA04 GA06 GB01 JA11 JA15 LA01 LA22 MA01 MA02 MA03 MA04

Claims (13)

[Claims] 1. A frost detecting means for detecting frost adhering to an evaporator of a refrigeration cycle, a defrosting means for removing frost adhering to the evaporator, and the defrosting means based on a signal from the frost detecting means. A defrost control device comprising: defrost control means for controlling the operation of the frost means. 2. A cooling air blower fan for circulating cool air cooled by a refrigeration cycle having a compressor, a condenser, a decompressor, and an evaporator in a refrigerator, and a defrost heater for removing frost attached to the evaporator. An operation control unit for controlling the operation of the compressor, the cool air blower fan, and the defrost heater; A defrosting control device comprising a frosting detection means for detecting a frosting state of the evaporator. 3. The frost detection means includes a temperature detection element including a first system for detecting a temperature of the evaporator itself and a second system for detecting a cool air temperature around the evaporator. The defrost control device according to claim 1 or 2, wherein 4. When two or more sets of the frost detection means are mounted on the evaporator, and when at least one set of temperature difference is equal to or less than a set value, the driving of the compressor and the cool air blowing fan is stopped, 4. The defrost control device according to claim 1, wherein the defrost heater is energized to start defrost. 5. 5. A defrost control method for starting defrost of frost adhering to the evaporator when a temperature difference between the evaporator main body and the periphery of the evaporator becomes equal to or less than a predetermined value. 6. Defrosting of frost adhering to the evaporator is started when a predetermined time has elapsed in the operation of the refrigeration cycle including the evaporator or when the evaporator is at or below a predetermined temperature. The defrost control method described in 1. 7. The defrosting apparatus according to claim 5, wherein, even when the temperature difference is equal to or more than a predetermined value, defrosting of the frost attached to the evaporator is started when a predetermined defrost cycle time has elapsed. Defrost control method. 8. The defrost according to claim 5, 6 or 7, wherein the defrosting of the evaporator is terminated when the temperature around the evaporator main body or around the evaporator reaches a predetermined value. Control method. 9. A refrigerator comprising the defrost control device according to claim 1. Description: 10. A refrigerator provided with a control unit for changing the cumulative operation time of the compressor until the start of the next defrost based on the operation speed of the compressor and the number of times the door is opened and closed. 11. The control unit detects an operating speed of the compressor every predetermined time after completion of the defrosting operation, integrates a predetermined weighting coefficient value for each operating speed, and calculates the integrated value. The refrigerator according to claim 10, wherein the next defrosting is started when the temperature reaches a predetermined value. 12. The weighting coefficient value is set to a smaller value as the operating speed of the compressor is lower.
Or the refrigerator according to 11. 13. The weighting coefficient value after the start of defrosting
The weighting coefficient value when the state where the door opening / closing operation is not continued and the weighting coefficient value after the door opening / closing operation are performed are distinguished, and the former weighting coefficient value is greater than the latter weighting coefficient value. 12. The method according to claim 10, wherein the value is set to a small value.
Or the refrigerator according to 12.