JPH1019448A - Freezing refrigerator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To save energy by canceling a defrosting operation and setting a normal cooling operation only when a temperature change rate between the temperature at the time of starting the defrosting operation and the temperature after a lapse of a given time from the starting of defrosting operation is larger than a predetermined value. SOLUTION: An evaporator 3 is monitored by a temperature sensor 17 which constitutes temperature detecting means and is arranged in a space located above and at a right side of the evaporator 3. In response to an output of the temperature sensor 17, the temperature change of the evaporator 3 within a given time is calculated by temperature calculating means 18. It is judged whether the calculated result falls within a predetermined temperature difference or not. In such a judgment, only when the calculated result exceeds the predetermined temperature difference, a defrosting switch 19 is turned off so that a defrosting mode is canceled and an operation returns to a normal operation mode. Due to such a construction, electric energy which becomes necessary for feeding electricity to a defrosting heater 6 and electric energy for cooling the heat generation rate of the defrosting heater 6 can be reduced thus enabling an energy saving.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerator and, more particularly, to an operation control of a refrigerator which heats and defrosts an evaporator.

[0002]

2. Description of the Related Art FIGS. 8 to 10 show an example of a conventional refrigerator of this type as disclosed in Japanese Utility Model Laid-Open Publication No. 60-65582,
1 shows a refrigerant circuit block diagram of a refrigerator-freezer disclosed in JP-A-2-33592 and a schematic diagram of a main part of the refrigerator-freezer.

[0003] 1 is a refrigerator box, 2 is an evaporator chamber provided at the upper rear side of the box, 3 is an evaporator disposed in the evaporator chamber 2, and 4 is for supporting the evaporator 3. , A pair of end plates 5, a pair of heat convection guides attached to the lower part of the end plate 4 with their tips directed inward, respectively, and 6 a defrosting means ( A defrost heater 7 is provided above the defrost heater 6, a toy 8 is disposed at the lowermost portion 5 of the evaporator chamber 2, and a toy for receiving frost-melting water is provided. Evaporator 3
Is a sump tank connected to the outlet side of the evaporator 3 and disposed above the evaporator 3. Numeral 10 is a cool air blowing means provided at the upper part of the evaporator chamber 2 for forcibly convection the cool air cooled by heat exchange with the evaporator 3 into the refrigerator.

A defrost timer 11 accumulates the operation time of the compressor 12 to stop the operation of the compressor 12 at regular intervals, activates the defrost heater 6, and controls the temperature of the evaporator 3. Is for restarting the compressor 12 after reaching a predetermined temperature.

[0005] 13 is a bimetal switch connected in series to the defrost heater 6, 14 is an internal temperature detecting means connected in series to the compressor 12 via a defrost timer 11, 15 is a condenser, and 16 is a decompression device is there. The refrigeration cycle circuit is configured by sequentially connecting the evaporator 3, the reservoir tank 9, the compressor 12, the condenser 15, and the pressure reducing device 16 through a refrigerant line.

As described above, since the conventional refrigerator-freezer is installed below the evaporator 3 of the defrost heater 6, a part of the air heated by the defrost heater is located above, ie, the evaporator 3 Natural convection to the lower part, and a part of the heated air is guided by the heat convection guide 5 and naturally convects to both sides of the evaporator 3. Part of the convection flows to the center of the evaporator 3.

[0007] Accordingly, the frost adhering to the surface of the evaporator 3 and the sump tank 9 is defrosted by exchanging heat with air that naturally flows upward.

When the temperature of the evaporator 3 rises and reaches a predetermined temperature and the bimetal switch 13 is operated, the heating of the defrost heater 6 is stopped, and after a certain period of time, a normal cooling operation is performed.

[0009]

However, in the above-mentioned defrosting method, the defrosting heater 6 is not used until the temperature of the evaporator 3 reaches a predetermined temperature during defrosting regardless of the amount of frost on the evaporator 3.
, It not only raises the temperature of the evaporator 3 even when there is almost no frost and there is no need for defrosting, but also raises the temperature of peripheral parts and the like at the same time to melt the frost. In addition to the original role, the amount of heat of the defrost heater 6 is used, which is very inefficient.

Further, the food temperature in the freezer compartment temporarily rises due to the heat load generated at the time of defrosting, so that the quality of the food tends to deteriorate. Moreover, since the inside temperature of the refrigerator is high after the completion of the defrosting, the operation time of the compressor 12 after the completion of the defrosting is prolonged, which leads to an increase in power consumption.

[0011] As described above, the conventional defrosting by the heater heating method has major drawbacks in terms of both power consumption and food preservation.

The present invention solves the above-mentioned problems of the conventional example. By selecting whether or not to enter the defrosting mode according to the amount of frost on the evaporator 3, an energy-saving refrigerator-freezer is provided. Is provided.

Further, since the temperature of the food in the freezer compartment during defrosting can be prevented from being significantly increased, the temperature of the food in the refrigerator can be kept almost constant, and the food can be freshened and maintained with high quality. There is no innovative refrigerator-freezer.

[0014]

According to a first aspect of the present invention, there is provided a refrigerator-freezer which does not melt frost of an evaporator by heating a defrost heater at regular time intervals but employs the above-described structure.
Based on the output from the temperature detecting means attached to the space above the evaporator, the state of frost formation on the evaporator is calculated, and if it is determined that the frost has hardly formed, defrosting is terminated at that point, and the normal Control to return to cooling operation.

Thus, it is possible to provide a refrigerator-freezer which can save energy and maintain freshness of food at high quality.

[0016] The refrigerator according to claim 2 of the present invention comprises:
Defrosting is terminated at that point if the rate of temperature change of all of the plurality of temperature detecting means installed in the space above the evaporator by heating of the defrost heater is larger than a preset value,
Control is performed to return to the normal cooling operation.

Thus, it is possible to provide a refrigerator which can save energy and maintain freshness of food at high quality.

[0018] The refrigerator according to claim 3 of the present invention comprises:
By the temperature detecting means installed in the space above the evaporator, the state of frost formation on the evaporator is determined from the temperature change rate immediately after the compressor stops during the normal cooling operation. Control so as not to enter.

As a result, it is possible to provide a refrigerator which can save energy and maintain freshness of food at high quality.

[0020]

DETAILED DESCRIPTION OF THE INVENTION According to the first aspect of the present invention, a temperature detecting means mounted in a space above an evaporator of a cooling system, and a temperature change rate based on an output from the temperature detecting means. The evaporator is constituted by a temperature change rate calculating means for calculating, and only when the temperature change rate at the start of defrosting and after a certain time is larger than a preset value is controlled to release the defrost and enter a normal cooling operation mode. When there is almost no frost, the cooling operation is continued without entering the defrost mode, and the amount of power for energizing the heater and the amount of power for cooling the calorific value can be reduced. Can be provided. Moreover, since there is almost no heating of the defrost heater, there is almost no rise in the temperature of the food in the freezing room or the refrigerator compartment, so that it has the effect that high-quality food freshening is possible.

According to a second aspect of the present invention, a plurality of temperature detecting means installed in a space above the evaporator of the cooling system, and a temperature change rate is calculated based on an output from the temperature detecting means. A temperature change rate calculation means is provided, and only when any of a plurality of temperature change rates at the start of defrosting and after a certain time is larger than a preset value, defrosting is released and a normal cooling operation mode is set. The defrost heater is detected without any frost on the evaporator, and the cooling operation is continuously performed without entering the defrost mode. Since the amount of electric power for cooling can be reduced, an energy-saving refrigerator-freezer can be provided. Moreover, since there is almost no heating of the defrost heater, there is almost no rise in the temperature of the food in the freezing room or the refrigerator compartment, so that it has the effect that high-quality food freshening is possible.

According to a third aspect of the present invention, there is provided a temperature detecting means mounted in a space above an evaporator of a cooling system, and a temperature changing rate for calculating a temperature changing rate based on an output from the temperature detecting means. When the temperature change rate immediately after the compressor operation is stopped during the normal cooling operation is large, the evaporator is controlled to be in the normal cooling operation mode without entering the defrosting mode. The defrost heater is reliably detected, and control is performed so that the cooling operation continues without entering the defrost mode, and the amount of power for energizing the defrost heater and the amount of power for cooling the calorific value are reduced. As a result, an energy-saving refrigerator-freezer can be provided.
Moreover, since there is almost no heating of the defrost heater, there is almost no rise in the temperature of the food in the freezing room or the refrigerator compartment, so that it has the effect that high-quality food freshening is possible.

A refrigerator-freezer according to an embodiment of the present invention will be described below with reference to FIGS. The same components as those of the conventional example are denoted by the same reference numerals, and detailed description thereof will be omitted.

(Embodiment 1) Reference numeral 17a denotes a temperature detecting means mounted in the upper right space of the evaporator 3, and is a temperature sensor for monitoring the evaporator 3.

Reference numeral 18 denotes a temperature change rate calculating means having a function of calculating a temperature change of the evaporator 3 within a predetermined time based on the output of the temperature detecting means 17.

Reference numeral 19 denotes a defrost switch for turning on and off the defrost heater 6 based on the result of the temperature change rate calculating means 18.

The operation of the refrigerator having the above-described structure will be described with reference to the flowchart of FIG.

The refrigerator-freezer is normally cooled in the cooling operation mode, but enters the defrost mode after a predetermined time set by the defrost timer has elapsed.

First, the temperature detecting means 17 measures the initial temperature Ts of the evaporator 3 at the start of defrosting, and then the defrosting switch 19 is turned on to energize the defrosting heater.

When a predetermined time (for example, three minutes) has elapsed, the temperature detecting means 17 again measures the defrosting intermediate point temperature Te.

The temperature change rate calculating means 18 calculates a temperature rise ΔT = Te−Ts for a predetermined time, for example, three minutes, and determines whether the result of ΔT is a predetermined temperature difference, for example, 10K or more. judge.

The fact that the temperature in the space above the evaporator 3 rises by 10 K or more means that the amount of frost formed around the temperature detecting means 17 is small.
This means that there is little frost on the surface and there is no need for defrosting.

Therefore, when it exceeds 10K (YE in FIG. 3)
In S), the defrost switch 19 is turned off, the defrost mode is released here, and the normal operation mode is returned.

On the other hand, when the temperature rise ΔT is 10K or less, the defrosting mode is continued, and when the temperature Tn of the temperature detecting means 17a exceeds, for example, 20 ° C., the defrosting is completed and then the normal operation mode is set. Let it return.

As described above, in the conventional method, the defrost heater 6 is energized and heated after a certain period of time, even when the temperature of the evaporator 3 hardly defrosts and the defrost is unnecessary. The temperature of the food placed in the freezer or the like has risen due to the use of wasted electric power or the generation of heat, thereby deteriorating the freshness of the food.
If the amount of frost is small based on the result detected by a, control is performed so that the defrost is terminated at the beginning of the defrost mode and a normal cooling operation mode is entered. This eliminates the need for energy for cooling the heat load generated by the heat generated by the heat generation, and also minimizes the temperature rise of the food in the refrigerator, so that the freshness of the food can be kept high.

(Embodiment 2) FIG. 4 is a front view of a main part of a refrigerator-freezer according to a second embodiment of the present invention.
FIG. 5 is a flowchart of the control of the refrigerator-freezer according to the second embodiment of the present invention.

The temperature detecting means 17a is provided at the upper right of the evaporator 3, and the temperature detecting means 17b is provided at the upper left of the evaporator 3.

The operation of the refrigerator constructed as described above will be described with reference to the flowchart of FIG.

The refrigerator-freezer is normally cooled in the cooling operation mode, but enters the defrost mode after a predetermined time set by the defrost timer has elapsed.

First, the initial temperatures Tsa and Tsb at the start of defrosting of the evaporator 3 are measured by the temperature detecting means 17a and 17b, and then the defrost switch 19 is turned on and the defrost heater is energized.

Then, when a predetermined time (for example, 3 minutes) has elapsed, the defrosting intermediate point temperatures T3a and T3b are measured again by the temperature detecting means 17a and 17b.

Next, the temperature rise rates ΔTa, ΔTb for a predetermined time of 3 minutes are calculated by the temperature change rate calculating means 18 .DELTA.Ta = T3a-Tsa.DELTA.Tb = T3b-Tsb. It is determined whether or not the difference is a preset temperature difference, for example, 10K or more.

The fact that the temperature of the air above the evaporator 3 rises by 10 K or more means that the amount of frost formed around the temperature detecting means 17 is small.
This means that there is little frost on the surface and there is no need for defrosting.

Therefore, when it exceeds 10K (YE in FIG. 6)
In S), the defrost switch 19 is turned off, the defrost mode is released here, and the normal operation mode is returned.

On the other hand, when the temperature rise ΔTa, b is 10 K or less, the defrosting mode is continued as it is,
When both of the temperatures Tn of a and b exceed, for example, 20 ° C., the defrosting is terminated, and then the operation mode is returned to the normal operation mode.
That is, that the temperature rise of all the plurality of temperature detecting means is fast means that the frost amount is small in any part of the evaporator 3, and the defrost mode is passed only when this condition is satisfied.

As described above, in the conventional method, the defrost heater 6 is energized and heated after a certain period of time, even when the temperature of the evaporator 3 hardly defrosts and defrosting is unnecessary. The temperature of the food placed in the freezer or the like has risen due to the use of wasted power to the refrigerator or the heat generated, thereby deteriorating the freshness of the food.
7a, b,... Based on the detection results, it is determined that the amount of frost is small, and control is performed so that defrosting is terminated at the beginning of the defrosting mode and the normal cooling operation mode is entered. Energy for cooling the heat load generated by the input of the frost heater 6 and the heat generated during the defrosting becomes unnecessary, and the temperature rise of the food in the refrigerator can be minimized, so that the freshness of the food can be kept high.

(Embodiment 3) As shown in FIG. 6, a temperature detecting means 17c is provided in the upper space of the evaporator 3.

The operation of the refrigerator having the above-described structure will be described with reference to the flowchart of FIG.

In the refrigerator, the compressor of the cooling system is normally turned on and off to keep the temperature in the refrigerator constant. This compressor is O
Starting temperature Ts by temperature detecting means 17 at the same time as FF
Is detected.

After a predetermined time, for example, three minutes, the temperature T3 is detected by the temperature detecting means 17 again.

Then, the defrost timer is periodically entered into the defrost mode by the defrost timer, and ΔT = T3-TS by the temperature difference calculating means 20.
Is calculated.

If ΔT is larger than a preset value, for example, 5K, the defrosting mode is passed and the operation returns to the normal operation mode. In other words, although the temperature of the evaporator rises from the time when the compressor is stopped, it can be said that if the amount of frost is small, the temperature rise is large and defrosting is not necessary.

On the other hand, if .DELTA.T is smaller than a preset value 5K, the defrosting mode is continued if the temperature detection Tn of the temperature detecting means 17c exceeds, for example, 20.degree. End and return to normal operation mode.

[0054]

As described above, according to the present invention, instead of melting the frost of the evaporator by heating the defrost heater at regular time intervals, the above structure allows the temperature attached to the upper space of the evaporator to be increased. Based on the output from the detection means, the state of frost formation on the evaporator is estimated and calculated, and if it is determined that frost is hardly formed, defrosting is terminated at that point and control is performed so as to return to normal cooling operation.

When the evaporator has almost no frost, the cooling operation is continuously performed without entering the defrosting mode, and the amount of electric power for energizing the heater and the amount of electric power for cooling the calorific value are provided. Therefore, an energy-saving refrigerator-freezer can be provided. Moreover, since there is almost no heating of the defrost heater, there is almost no rise in the temperature of the food in the freezer or refrigerator compartment, and the advantageous effect that high-quality food freshness is possible is obtained.

Further, a plurality of temperature detecting means are installed in the upper space of the evaporator, and if all of these temperature change rates due to heating of the defrost heater are larger than a preset value, the defrosting is terminated at that time. Control is performed to return to the normal cooling operation.

Thus, it is possible to more reliably detect that the evaporator is almost free of frost, and to continue the cooling operation without entering the defrosting mode. Since the amount of electric power for cooling the refrigerator can be reduced, an energy-saving refrigerator-freezer can be provided.
Moreover, since there is almost no heating of the defrost heater, there is almost no rise in the temperature of the food in the freezer or refrigerator compartment, and the advantageous effect that high-quality food freshness is possible is obtained.

Immediately after the compressor is stopped during the normal cooling operation, the state of frost formation on the evaporator is determined from the temperature change rate of the air above the evaporator. If the frost formation state is larger than a preset value, the defrosting mode is not entered. Control.

When the evaporator is almost free of frost, the cooling operation is continuously performed without entering the defrosting mode. The amount of electric power for energizing the heater and the amount of electric power for cooling the calorific value are provided. Since the amount can be reduced, an energy-saving refrigerator-freezer can be provided. Moreover, since there is almost no heating of the defrost heater, there is almost no rise in the temperature of the food in the freezer or refrigerator compartment, and the advantageous effect that high-quality food freshness is possible is obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing a cooling system and an electric wiring diagram of a refrigerator according to an embodiment of the present invention.

FIG. 2 is a front view of a main part of the refrigerator according to the embodiment.

FIG. 3 is a flowchart of the refrigerator-freezer in the embodiment.

FIG. 4 is a front view of a main part of a refrigerator-freezer according to a second embodiment.

FIG. 5 is a flowchart of the refrigerator-freezer in the embodiment.

FIG. 6 is a front view of a main part of a refrigerator according to a third embodiment.

FIG. 7 is a flowchart of the refrigerator-freezer in the embodiment.

FIG. 8 is a central sectional view of a conventional refrigerator-freezer.

FIG. 9 is a cooling system diagram and electric wiring diagram center sectional view of a conventional refrigerator-freezer.

FIG. 10 is a front view of a main part of a conventional refrigerator-freezer.

[Explanation of symbols]

 Reference Signs List 3 evaporator 6 defrost heater 17a, b, c temperature detecting means 18 temperature change rate calculating means 21 defrost switch

Claims (3)

[Claims] 1. A defrost heater provided separately from an evaporator of a cooling system, temperature detecting means mounted in a space above the evaporator, and a temperature for calculating a temperature change rate based on an output from the temperature detecting means. A refrigerating refrigerator comprising a change rate calculating means, wherein only when the temperature change rate at the start of defrosting and after a predetermined time is greater than a preset value, defrosting is released and the refrigerator is controlled to be in a normal cooling operation mode. A defrost heater provided separately from the evaporator of the cooling system; a plurality of temperature detecting means mounted in a space above the evaporator; and a temperature change rate based on an output from the temperature detecting means. It comprises a temperature change rate calculating means for calculating, and when only one of a plurality of temperature change rates at the start of defrosting and after a certain time is larger than a preset value, the defrosting is released and a normal cooling operation mode is set. Refrigerator-freezer controlled to become. 3. A defrost heater provided separately from an evaporator of a cooling system, temperature detecting means mounted in a space above the evaporator, and a temperature for calculating a temperature change rate based on an output from the temperature detecting means. A refrigerating / refrigerating refrigerator comprising a change rate calculating means, which controls a normal cooling operation mode without entering a defrosting mode when a temperature change rate immediately after a compressor operation is stopped during a normal cooling operation is large.