JPH0894234A - Defrosting device for refrigerator - Google Patents

Abstract

PURPOSE: To always achieve defrosting operation in response to the actual amount of frosting by estimating the amount of frosting based upon a temperature change rate by temperature change rate-operating means and fresh air temperature by fresh air temperature-detecting means, and determining defrosting completion decision temperature based upon the estimated amount of frosting. CONSTITUTION: A change rate of detected temperature by a defrosting temperature sensor 14 is calculated with temperature change rate-operating means of a control circuit 15 after power supply to a defrosting heater 13 is started. The amount of frosting is estimated with frosting amount estimation means of the control circuit 15 based upon the calculated temperature change rate and fresh air temperature by a fresh air temperature sensor 16 being fresh air temperature detecting means. Defrosting completion decision temperature is determined with defrosting completion decision temperature determination means of the control circuit 15 based upon the estimated amount of frosting by the frosting amount estimating means. Hereby, defrosting operation is always achieved in response to the actual amount of frosting, and temperature rise in a refrigerator can be reduced to eliminate wasteful consumed power.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerator defrosting device having an improved defrosting control.

[0002]

2. Description of the Related Art Conventionally, in a fan-cool type refrigerator, for example, air cooled by a cooler (cool air) is circulated in a refrigerator by a fan to cool the inside. In this case, some of the water content of the cool air flowing through the cooler portion becomes frost and adheres to the cooler. Therefore, as is well known, the defrosting operation is performed on the cooler at a predetermined defrosting timing. This defrosting operation is such that the defrosting heater is energized and the defrosting heater is turned off when the cooler reaches a predetermined defrosting end determination temperature.

The above defrosting end judgment temperature is set under the harsh condition that the amount of frost is large, for example, the condition that the refrigerator door is opened and closed many times due to high temperature and humidity, and thus even when the amount of frost is large. I am sure that defrost is done.
Conventionally, the temperature has been uniquely set to, for example, 13 ° C. with some margin.

[0004]

However, in the above-mentioned conventional one, for example, when the refrigerator door is opened and closed at a low room temperature and the number of times of opening and closing is small, the actual amount of frost is small and the defrosting time becomes longer than necessary. , Waste of power consumption increases.
Furthermore, in this case, the extra power supply to the defrost heater
There is a problem that the temperature inside the refrigerator also rises, and in this case, the operating time of the compressor after the defrosting recovery also becomes long, and this also causes a problem that power consumption is wasted.

The present invention has been made in view of the above circumstances, and an object thereof is not only to ensure defrosting, but also to always perform defrosting operation according to an actual amount of frost formation. An object of the present invention is to provide a defrosting device for a refrigerator that can reduce the temperature rise in the refrigerator and reduce power consumption.

[0006]

A first means is a defrosting heater for defrosting a cooler, a defrosting temperature detecting means for detecting a defrosting state of a cooler, and an electric current is supplied to the defrosting heater. Defrosting operation means for turning off the defrosting heater when the defrosting end determination temperature is detected based on the defrosting temperature detecting means, outside air temperature detecting means for detecting the temperature around the refrigerator, and the defrosting heater Temperature change rate calculating means for calculating the change rate of the detected temperature of the defrosting temperature detecting means after the start of energization for the, and the temperature change rate by the temperature change rate calculating means and the frost formation amount by the outside air temperature detecting means. The frost formation amount estimation unit and the defrosting end determination temperature determining unit that determines the defrosting end determination temperature based on the estimated frost formation amount by the frosting amount estimation unit are configured (the invention of claim 1 ).

The second means is a defrost heater for defrosting the cooler, a defrost temperature detecting means for detecting the defrosting state of the cooler, and the defrost heater is energized so that the defrost temperature detecting means operates. Based on the defrosting end determination temperature is detected based on the defrosting operation means for de-energizing the defrosting heater, the outside air temperature detecting means for detecting the temperature around the refrigerator, the defrosting heater after the start of energization Detecting that the cooler is in the melting temperature state, measuring means for measuring the duration of this melting temperature state, the melting temperature duration by this measuring means and the outside air temperature by the outside air temperature detecting means to determine the amount of frost. The frost formation amount estimating means for estimating and the defrosting end determination temperature determining means for determining the defrosting end determination temperature based on the estimated frost formation amount by the frosting amount estimation means are configured (claim 2 Invention).

A third means is a defrost heater for defrosting the cooler, a defrost temperature detecting means for detecting the defrosting state of the cooler, and the defrost heater is energized to cause the defrost temperature detecting means to operate. Based on the defrosting end determination temperature is detected based on the defrosting operation means for de-energizing the defrosting heater, the outside air temperature detecting means for detecting the temperature around the refrigerator, the defrosting heater after the start of energization Temperature change rate calculating means for calculating the change rate of the detected temperature of the defrosting temperature detecting means, and detecting that the cooler is in a melting temperature state after the start of energization to the defrosting heater, and the melting temperature state is continued. Measurement means for measuring time, frost formation amount estimation means for estimating the frost formation amount by the temperature change rate by the temperature change rate calculation means, the outside air temperature by the outside air temperature detection means, and the melting temperature duration by the measurement means , This frost Configured to include a defrosting end determination temperature determination means for determining the defrosting end determination temperature based on the estimated frost amount by estimating means (the invention of claim 3).

A fourth means is any one of the first to third means, and door opening / closing counting means for counting the number of times the refrigerator door is opened / closed between the previous defrosting operation and the current defrosting operation, An average outside air temperature calculating means for calculating the average outside air temperature from the last defrosting operation to the current defrosting operation is provided, and the frost formation amount estimating means is the number of times of opening and closing the door by this door opening and closing counting means and the average outside air temperature. The present invention is characterized in that the amount of frost formation is estimated in consideration of the average outside air temperature calculated by the calculating means (the invention of claim 4).

[0010]

When the defrosting operation is started, the temperature of the cooler rises from, for example, about -30 ° C. When the frost starts to melt, the melting temperature (usually 0 ° C.) is maintained until almost all the frost melts, and then the cooling temperature rises again. In this case, the amount of frost on the cooler can be determined to some extent based on the outside air temperature. Further, the amount of frost formation can be determined by the degree of temperature rise of the cooler at the beginning of the defrosting operation. That is,
When the amount of frost is small, the degree of change in the temperature of the cooler, that is, the rate of change is large. Conversely, when the amount of frost is large,
The degree of increase in the temperature of the cooler, that is, the rate of change also decreases. Furthermore, the amount of frost formed on the cooler can also be determined by the length of the duration of the melting temperature state.

In the first means, however, the frost formation amount is estimated by the temperature change rate by the temperature change rate calculation means and the outside air temperature by the outside air temperature detection means. It can be estimated well, and the defrosting end determination temperature is determined based on the estimated frost formation amount.
The defrosting heater is turned off, that is, the defrosting operation is terminated based on the defrosting end determination temperature suitable for the frosting amount, and the optimal defrosting operation according to the frosting amount is performed.

Further, in the second means, the amount of frost to be actually defrosted is satisfactorily estimated because the frosting amount is estimated by the melting temperature duration by the measuring means and the outside air temperature by the outside air temperature detecting means. Since the defrosting end determination temperature is determined based on the estimated frosting amount, the defrosting heater is turned off, that is, the defrosting operation ends based on the defrosting ending determination temperature suitable for the frosting amount. The optimum defrosting operation according to the amount of frost formation is performed.

In the third means, the frosting amount is estimated by the temperature change rate by the temperature change rate calculating means, the outside air temperature by the outside air temperature detecting means, and the melting temperature duration time by the measuring means, so that defrosting is actually performed. It is possible to more accurately estimate the amount of frost to be used, and the defrost end determination temperature is determined based on this accurate estimated frost formation amount. As a result, the defrosting heater is cut off, that is, the defrosting operation is terminated, and the optimum defrosting operation according to the amount of frost formation can be performed even better.

In the fourth means, the number of times the refrigerator door is opened and closed from the previous defrosting operation to the current defrosting operation is counted, and the average from the previous defrosting operation to the current defrosting operation is counted. Since the outside air temperature is calculated and the frosting amount is estimated by adding the number of times of opening and closing of the door and the average outside air temperature, the estimation result of the frosting amount becomes more accurate, and the defrosting operation is further improved. Will be carried out.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS. First, in FIG. 2, the refrigerator main body 1 has a configuration in which a freezer compartment 2, a refrigerator compartment 3 and a vegetable compartment 4 are vertically provided, and doors 2a to 4a, which are refrigerator doors, are provided on the front surface of each compartment. A cooler chamber 5 is provided inside the freezing chamber 2, and a cooler 6 and a fan device 7 for circulating cold air are arranged in the cooler chamber 5. A duct 8 communicating with the cooler chamber 5 is provided at the back of the refrigerating chamber 3, and cold air is supplied to the refrigerating chamber 3 and the vegetable chamber 4 through the duct 8. In this case, the duct 8 is configured to be opened and closed by a damper device 9 that responds to the temperature inside the refrigerator compartment 3.

At the outside lower part of the refrigerator body 1, a machine room 10 is provided.
A compressor 11 for driving the refrigeration cycle including the cooler 6 is arranged in the machine room 10. A freezing compartment temperature sensor 12 for detecting the internal temperature of the freezing compartment 2 is arranged, and the operation output of the compressor 11 is controlled by the detection output of the temperature sensor 12. In the cooler chamber 5, a defrosting heater 13 made of, for example, a glass tube heater is provided so as to be positioned below the cooler 6, and the cooler 6 is supplied with electricity when the defrosting heater 13 is energized. The defrosting operation is performed. Further, a defrosting temperature sensor 14, which is a defrosting temperature detecting means for detecting the temperature, is provided at an upper portion of the cooler 6 (a portion where frost is likely to remain until the end during defrosting).

FIG. 3 shows an outline of an electrical configuration related to defrost control. The control circuit 15 is configured to include a microcomputer and a driver circuit for driving a load, which includes a defrosting operation unit, a temperature change rate calculation unit, a frost formation amount estimation unit, and a defrosting end determination temperature determination unit. It functions as. The outside air temperature sensor 16, which is an outside air temperature detecting means, is provided at an appropriate location in the refrigerator body 1 to detect the temperature around the refrigerator. The temperature signals from the defrosting temperature sensor 14 and the outside air temperature sensor 16 are given to the control circuit 15. Then, the control circuit 15 controls the load of the defrost heater 13 and the like based on the input signal as described above and the preset control program. The part related to the gist of will be described together with the related operation.

FIG. 1 shows a flow chart of the control of the defrosting operation. This defrosting operation control is performed by the compressor 1
The operation is started when the accumulated operation time of 0 reaches a predetermined time. Further, in FIG. 4, the defrosting temperature sensor 1
4 shows the change in the detected temperature of No. 4. First, in step S1, the defrost heater 13 is energized and the defrost temperature sensor 1
Input the defrosting temperature detected by 4. This causes the temperature of the cooler 6 to rise. In step S2, the defrosting temperature detected by the defrosting temperature sensor 14 is the calculation start temperature K1 such as −3.
It is determined whether or not the temperature has reached 0 ° C., and if the temperature has reached 0 ° C., step S3
Then, the count of the soft timer by the microcomputer is started.

In the next step S4, the outside air temperature sensor 1
Input the detected outside air temperature of 6. Then, in step S5, it is determined whether the defrosting temperature detected by the defrosting temperature sensor 14 has reached the calculation end temperature K2, for example, -2 ° C. When it reaches, in step S6, the count of the soft timer is stopped, and the temperature change rate is calculated based on the count value of the timer (time A from the temperature K1 to K2 shown in FIG. 4). That is, the temperature change rate = (K2-K
1) / A. Then, in step S7, the average outside air temperature is calculated.

In step S8, the amount of frost formation is estimated and the defrosting end determination temperature is determined. That is, as shown in FIG. 5 and Table 1, according to the experiment of the present inventor, under a certain constant outside air temperature condition, the larger the amount of frost is, the higher the rate of change (increase rate) of the defrosting temperature of the cooler 6 is. Was found to be low. It was also found that the higher the outside air temperature, the greater the amount of frost formation. It was also found that the larger the amount of frost formed, the more energy required for defrosting, and the higher the temperature for determining the end of defrosting. Therefore, the change rate of the detected defrosting temperature and the outside air temperature (in this embodiment, the average outside air temperature at the initial stage of defrosting)
The amount of frost can be estimated by and. Then, the defrosting end determination temperature Kα (see FIG. 4) is determined based on the estimated frost formation amount. That is, it is conceivable that the defrosting end determination temperature is set to 2 ° C. when the frost formation amount is, for example, the minimum value (for example, 0 cc), and 13 ° C. when the maximum value (for example, 400 cc in general use). Therefore, for example, the amount of frost is 200c
When the temperature is c, the defrosting end determination temperature may be 6 ° C.

[0021]

[Table 1]

Even after this, the frost attached to the cooler 6 is melted, but the detected defrosting temperature is maintained at the melting temperature (0 ° C.) until the frost is almost liquefied. It should be noted that the detected defrosting temperature is the melting temperature continuation start temperature Y1 (same as K2 is -2).
It is considered that the frost is in a melted state from the melting temperature continuation end temperature Y2 to, for example, 2 ° C.

After step S8, the process proceeds to step S9, and it is determined whether the defrosting temperature detected by the defrosting temperature sensor 14 has reached the determined defrosting end determination temperature Kα. If it reaches, it moves to step S10 and the defrost heater 1
Turn off 3. For example, the defrosting end determination temperature Kα is as shown in FIG.
For example, when the temperature is 5 ° C., the defrosting heater 13 is cut off and the defrosting operation ends when the temperature reaches 5 ° C., as shown in FIG. The defrosting end determination temperature Kα is determined within the temperature range indicated by the symbol C in FIG. 4 based on the estimated frost formation amount.

According to this embodiment, the change rate of the defrosting temperature detected by the defrosting temperature sensor 14 is calculated during the defrosting operation, and the amount of frost formation is estimated based on this temperature change rate and the outside air temperature. Since the amount of frost to be actually defrosted can be properly estimated, and the defrosting end determination temperature Kα is determined based on the estimated amount of frosting, the defrosting end determination temperature suitable for the amount of frost formation. Based on Kα, the defrosting heater 13 is cut off, that is, the defrosting operation is terminated, and the optimal defrosting operation according to the amount of frost formation is performed. As a result, not only can defrost be reliably performed, but it is also possible to always perform the defrost operation according to the actual amount of frost formation, and it is possible to prevent the defrost operation from being unnecessarily long, and thus It is possible to reduce the temperature rise of the device and to reduce the waste of power consumption.

By the way, when the amount of frost formation is considerably small, the defrosting end determination temperature Kα is set low, in other words, defrosting is performed earlier than the conventional defrosting end point (Jp in FIG. 4). It will be possible to finish the frost, for example 400
In a liter class refrigerator, it can be shortened by about 5 to 8 minutes. For example, input the defrost heater 13 to 164
[W / h] and the defrosting operation is performed once a day. If the defrosting operation is reduced to 8 minutes and converted into an electricity bill, 164 × (8/60) = 22 [W / Day], and since the temperature rise due to the defrosting operation is also suppressed, the cooling energy at the time of restarting the cooling operation is also reduced, resulting in a reduction of 2 × 22 [W / day]. Converting this to the electricity bill for January, the reduction is 0.67.
It also becomes [KW / month]. Also, the temperature rise in the refrigerator can be suppressed, and it is about 2 deg in the freezer and about 1 d in the refrigerator.
It is possible to reduce eg.

6 to 8 show a second embodiment of the present invention. This embodiment differs from the first embodiment in the following points. That is, the control circuit 21 has a function as a measuring unit instead of having the temperature change rate calculating unit. In the flowchart of FIG. 7 showing the control contents, in step G2, it is judged whether or not the defrosting temperature detected by the defrosting temperature sensor 14 has reached the melting start temperature Y1. Start the soft timer count.

In the next step G4, the outside air temperature sensor 1
Input the detected outside air temperature of 6. Then, in step G5, it is determined whether or not the defrosting temperature detected by the defrosting temperature sensor 14 has reached the melting end temperature Y2, for example, 2 ° C. Once you reach
In step G6, the soft timer count is stopped and the melting temperature duration B (see FIG. 4) is measured with the count value of this timer. Then, in step G7, the average outside air temperature is calculated.

In step G8, the amount of frost formation is estimated and the defrosting end determination temperature is determined. That is, as shown in FIG. 8 and Table 1 above, according to the experiments by the present inventor, it was found that under a certain constant outside air temperature condition, the longer the melting temperature duration is, the longer the frost formation amount is. It was also found that the higher the outside air temperature, the greater the amount of frost formation. Also,
It was also found that the larger the amount of frost formed, the more energy required for defrosting, and the higher the temperature for determining the end of defrosting. Therefore, the amount of frost can be estimated from the melting temperature duration and the outside air temperature (average outside air temperature in this embodiment). Then, the defrosting end determination temperature Kα is determined based on this estimated frost formation amount as in the first embodiment. After step G8, the process is the same as in the first embodiment.

According to the second embodiment, since the amount of frost formation is estimated from the melting temperature duration B and the outside air temperature, the amount of frost to be actually defrosted can be well estimated, and Since the defrosting end determination temperature Kα is determined based on the estimated frosting amount, the defrosting heater is turned off, that is, the defrosting operation is terminated based on the defrosting ending determination temperature suitable for the frosting amount. As a result, the same effect as the first embodiment is obtained.

FIG. 9 shows a third embodiment of the present invention. This embodiment differs from the first embodiment in the following points. That is, in step P3, the first timer, which is a soft timer for calculating the temperature change rate, is started. In step P5, the detected defrosting temperature is the calculation end temperature K.
2 (melting temperature continuation start temperature Y1) is determined, and if reached, the first timer is stopped and the temperature change rate is calculated in step P6.
The average outside air temperature is calculated at 7.

Next, at step P8, the counting of the second timer for determining the end of melting temperature continuation is started. When the melting temperature continuation end temperature Y2 is reached (step P9), the counting of the second timer is stopped and the melting temperature continuation time B is measured (step P10). Then, in Step P11, the frost formation amount is estimated based on the temperature change rate, the melting temperature duration B, and the outside air temperature,
The defrosting end determination temperature Kα is determined based on this estimated frost formation amount.

According to the third embodiment, the amount of frost formation is estimated based on the temperature change rate, the outside air temperature, and the melting temperature duration B. Therefore, the amount of frost to be actually defrosted is estimated more accurately. Since the defrosting end determination temperature Kα is determined based on this accurate estimated frosting amount, the defrosting heater 13 is turned off based on the defrosting ending determination temperature Kα suitable for the frosting amount. That is, the defrosting operation is ended, and thus the optimum defrosting operation according to the amount of frost formation can be performed even better.

10 and 11 show a fourth embodiment of the present invention. The fourth embodiment differs from the first embodiment in the following points. That is, the control circuit 31 has
Signals are supplied from door switches 32 to 34, which are door opening / closing detecting means for detecting opening / closing of the doors 2a to 4a, respectively, and the control circuit 31 is not shown in the flowchart of FIG. The door switch 32 from the last defrosting operation to the current defrosting operation
The number of opening / closing times (total value) of 34 is stored, and the average value of the outside air temperature from the previous defrosting operation to the current defrosting operation is sequentially calculated. It also functions as a temperature calculating means.

In the flowchart shown in FIG. 11, in step T1, the number of times of opening and closing the doors 2a to 4a stored between the previous defrosting operation and the present defrosting operation is input, and in step T2, the previous defrosting operation is entered. The average outside air temperature calculated and stored from the frost operation to the current defrost operation is input. Then, steps T3 to T9 similar to steps S1 to S7 of the first embodiment are executed, and the process proceeds to step T10.
In this step T10, the temperature change rate obtained in step T8, the outside air temperature obtained in step T9, the number of times the door is opened and closed obtained in step T1, the average outside air temperature obtained in step T2 (the average outside air temperature in step T9, And the defrosting end determination temperature Kα is determined. That is, the amount of frost formation tends to increase as the number of times of opening and closing of the door increases, and the frost formation amount tends to increase as the average outside air temperature increases. The amount of frost formation is estimated by adding these tendencies.

According to the fourth embodiment, the number of times the doors 2a to 4a are opened / closed between the last defrosting operation and the current defrosting operation is counted, and the last defrosting operation to the current defrosting operation is performed. During this period, the average outside air temperature is calculated, and the amount of frost formation is estimated by adding the number of times the door is opened and closed and the average outside air temperature. Frost operation will be carried out even better.

[0036]

As is apparent from the above description, the present invention can obtain the following effects. According to the invention of claim 1, the frosting amount is estimated by the temperature change rate by the temperature change rate calculating means and the outside air temperature by the outside air temperature detecting means, so that the amount of frost to be actually defrosted is satisfactorily estimated. Since the defrosting end determination temperature is determined based on the estimated frosting amount, defrosting can be reliably performed, and defrosting operation according to the actual frosting amount can always be performed. It is possible to prevent the defrosting operation from being unnecessarily long,
Therefore, it is possible to reduce the temperature rise in the refrigerator and to reduce the waste of power consumption.

Further, according to the second aspect of the invention, the amount of frost to be actually defrosted is good because the frosting amount is estimated by the melting temperature duration by the measuring means and the outside air temperature by the outside air temperature detecting means. Since the defrosting end determination temperature is determined based on the estimated frost formation amount, the same effect as the invention of claim 1 can be obtained.

According to the invention of claim 3, the frost formation amount is estimated by the temperature change rate by the temperature change rate calculation means, the outside air temperature by the outside air temperature detection means, and the melting temperature duration by the measurement means. The amount of frost to be frosted can be more accurately estimated, and as a result, the optimum defrosting operation according to the amount of frost formation can be performed even better.

According to the fourth aspect of the present invention, the number of times the refrigerator door is opened and closed between the last defrosting operation and the current defrosting operation is counted, and the period between the last defrosting operation and the present defrosting operation is counted. The average outside air temperature in is calculated, and the frosting amount is estimated by adding the number of times of opening and closing the door and the average outside air temperature, so the estimation result of the frosting amount becomes more accurate, and the defrosting operation is performed. It will be performed even better.

[Brief description of drawings]

FIG. 1 is a flowchart of control contents showing a first embodiment of the present invention.

[Figure 2] Vertical side view of the refrigerator

FIG. 3 is a block diagram of an electrical configuration related to defrosting operation.

FIG. 4 is a diagram showing a change in temperature detected by a defrosting temperature sensor.

FIG. 5 is a diagram showing a relationship between a frost formation amount and a temperature change rate.

FIG. 6 is a diagram corresponding to FIG. 3 showing a second embodiment of the present invention.

FIG. 7 is a view equivalent to FIG.

FIG. 8 is a diagram showing the relationship between the amount of frost and the duration of melting temperature.

FIG. 9 is a view corresponding to FIG. 1 showing a third embodiment of the present invention.

FIG. 10 is a view corresponding to FIG. 3 showing a fourth embodiment of the present invention.

FIG. 11 is a view equivalent to FIG.

[Explanation of symbols]

1 is a refrigerator main body, 2a-4a is a door (refrigerator door), 6 is a cooler, 13 is a defrost heater, 14 is a defrost temperature sensor (defrost temperature detection means), 15 is a control circuit (defrost operation means, Reference numeral 21 denotes a control circuit (defrosting operation means, measuring means, frost formation amount estimation means, and defrosting end determination temperature determination means);
31 is a control circuit (defrosting operation means, temperature change rate calculation means,
The frost formation amount estimating means, the defrosting end determination temperature determining means, the door opening / closing counting means, and the average outside air temperature calculating means)

Claims (4)

[Claims] 1. A defrost heater for defrosting a cooler, a defrost temperature detecting means for detecting a defrosting state of a cooler, and a defrost on the basis of the defrost temperature detecting means by energizing the defrost heater. Defrost operation means for turning off the defrost heater when the end determination temperature is detected, outside air temperature detection means for detecting the temperature around the refrigerator, and defrost temperature detection after the start of energization of the defrost heater Temperature change rate calculation means for calculating the change rate of the detected temperature of the means, and frost formation amount estimation means for estimating the frost formation amount by the temperature change rate by the temperature change rate calculation means and the outside air temperature by the outside air temperature detection means. A defrosting device for a refrigerator, comprising: defrosting end determination temperature determining means for determining the defrosting end determination temperature based on the estimated frosting amount estimated by the frosting amount estimating means. 2. A defrosting heater for defrosting a cooler, a defrosting temperature detecting means for detecting a defrosting state of the cooler, and a defrosting method for energizing the defrosting heater based on the defrosting temperature detecting means. Defrosting operation means for turning off the defrost heater when the end determination temperature is detected, outside air temperature detecting means for detecting the temperature around the refrigerator, and the cooler melting after the start of energization of the defrost heater A frosting device that detects a temperature state and measures the duration of this melting temperature state, and a frosting amount that estimates the amount of frosting based on the melting temperature duration of this measuring device and the outside air temperature of the outside air temperature detecting device. A defrosting device for a refrigerator comprising: an amount estimating means; and a defrosting end determination temperature determining means that determines the defrosting end determination temperature based on the estimated frosting amount estimated by the frosting amount estimation means. 3. A defrosting heater for defrosting a cooler, a defrosting temperature detecting means for detecting a defrosting state of the cooler, and a defrosting method for energizing the defrosting heater based on the defrosting temperature detecting means. Defrost operation means for turning off the defrost heater when the end determination temperature is detected, outside air temperature detection means for detecting the temperature around the refrigerator, and defrost temperature detection after the start of energization of the defrost heater Temperature change rate calculating means for calculating the change rate of the detected temperature of the means, and detecting that the cooler is in a melting temperature state after the start of energization of the defrost heater, and measures the duration of this melting temperature state. Measurement means, frost formation amount estimation means for estimating the frost formation amount by the temperature change rate by the temperature change rate calculation means, the outside air temperature by the outside air temperature detection means, and the melting temperature duration by the measurement means, and this frost formation Quantity estimator Refrigerator defrosting device formed by and a defrosting end determination temperature determination means for determining the defrosting end determination temperature based on the estimated frost amount due. 4. Door opening / closing counting means for counting the number of times the refrigerator door is opened / closed between the last defrosting operation and the current defrosting operation, and an average between the last defrosting operation and the current defrosting operation. An average outside air temperature calculation means for calculating the outside air temperature is provided, and the frost formation amount estimation means estimates the frost formation amount in consideration of the number of times the door is opened and closed by the door opening and closing count means and the average outside air temperature by the average outside air temperature calculation means. The defrosting device for a refrigerator according to claim 1, wherein the defrosting device is for a refrigerator.