JPH0428990A - Electric refrigerator - Google Patents

Abstract

PURPOSE:To allow even and short time thawing by providing a far infrared heater having a dome-shaped reflector with vent holes to cover the back of it at the upper part, a defrosting pan having a heating heater and temperature detector on the base, and a temperature detector on the inside wall, and by opening a ventilation passage formed behind the reflector for controlling cold air inflow. CONSTITUTION:When a temperature detector 43 installed on the base detects the first given temperature, a far infrared heater 34 and heating heater 42 are continuously energized to rise rapidly a thawing temperature of frozen food, and then the intermittent energization rate of both heaters are reduced to the second and third steps. At the first and second steps, cold air is supplied uniformly to the frozen food through damper thermostat 19, 20 and through a plurality of vent holes 40 made in a reflector plate 39 to control a temperature rise of frozen food surface. At the third step, the damper thermostats 19, 20 are closed, preventing exhaust air in a thawing room 15 from being recovered to a chiller. After thawing completed, owing to the temperature control function of the damper thermostats 19, 20 operated at the second given temperature of the temp. detector 31, frozen food is automatically kept at an intermediate temperature between cold storage and freezer storage temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an electric refrigerator provided with a thawing chamber for frozen foods.

(Prior Art) The main parts of a conventional electric refrigerator capable of defrosting frozen foods (hereinafter simply referred to as a refrigerator) will be described below with reference to FIGS. 7 and 8. For example, it is common to have a thawing box using a heater, as shown in Japanese Patent Publication No. 48-25414.

That is, FIG. 7 is a perspective view of a defrosting box provided in a conventional refrigerator, and FIG. 8 is a sectional view taken along the line AA'. Reference numeral 1 denotes a thawing box, which has a box-shaped outer box 2 made of metal or synthetic resin, and an inner box 3 made of a metal with high thermal conductivity such as aluminum, which is arranged with an appropriate gap inside the box. It is configured. Reference numeral 4 denotes a linear heater, which is closely connected to the inner box 3 by means of an aluminum foil 5 so as to be sparsely connected to the bottom surface of the thawing box 1 and densely connected to the top surface thereof in a thermally conductive manner. 6 is outer box 2,
This is a heat insulating material interposed between aluminum foils 5.

In a conventional refrigerator having such a thawing box 1, when the frozen food 7 is placed on the bottom of the thawing box 1 and thawing is started, heat is applied from the entire circumference of the inner box 3 by the heat generated by the heater 4. The frozen food 7 is thawed almost uniformly.

(Problem to be Solved by the Invention) However, in the conventional thawing box 1 described above, the heat from the heater at the bottom of the thawing box 1 is directly conducted to the bottom of the frozen food 7 to defrost it; 1. Heat rays of wavelength 5p are emitted from the heater 4 from the top and side surfaces through the inner box 3.
Since the following near-infrared rays are only applied, there is almost no effect on defrosting, and heating and defrosting is achieved only by heat transfer due to convection of the warmed air inside the defrosting box l.

Therefore, there is a difference in the thawing speed between the deep center and the surface of the frozen food 7, resulting in uneven thawing, requiring a long time to thaw, and leaving raw foods such as fish meat unattended after thawing due to the high ambient temperature. Since deterioration occurs, the person who defrosts the product must monitor the completion of the defrosting process and cannot defrost the product with peace of mind.

In view of the above, an object of the present invention is to provide a refrigerator having a thawing chamber that can defrost food in a short time with less unevenness.

(Means for Solving the Problems) The present invention has achieved the above-mentioned object by providing a far-infrared heater having a reflector in the upper part with a dome-shaped ventilation hole covering the back, a heating heater in the bottom part, and a first temperature control plate in the bottom part. A thawing tray for food to be thawed is provided with a detector, a second temperature sensor is provided on the inner wall, and a damper thermostat is installed in the ventilation passage formed on the back surface of the reflector to adjust the amount of cold air inflow. The thawing chamber opened through the refrigerator is arranged in one section of the refrigerator compartment of the electric refrigerator, and during thawing, the blower is forcedly operated to connect the ventilation passage to the freezing chamber, and the far-infrared heater and heating heater are is operated continuously from the start of thawing until the temperature of the first temperature sensor on the bottom reaches a predetermined temperature in the first stage, and thereafter in the second stage. As the third stage, the energization rate of the far-infrared heater and heating heater is lowered in stages by intermittent operation, and the first stage. In the second stage, the damper thermostat is forcibly opened, and in the third stage, it is forcibly closed, and when the temperature of the second temperature sensor reaches the first predetermined temperature after a predetermined time, the far-infrared heater and the heating Stop energizing both heaters, and
This is achieved by a configuration in which the temperature of the second temperature sensor reaches a second predetermined temperature when not defrosting, thereby maintaining the defrosting chamber in a third temperature range between the refrigerating temperature and the freezing temperature.

(Function) According to the present invention having the above configuration, direct radiation of far infrared rays by the far infrared heater and indirect radiation through the reflection plate are performed on the food to be frozen, and heat transfer from the heater at the bottom part is performed. Heating occurs and heat is absorbed.

Further, when the first temperature sensor placed on the bottom detects the first predetermined temperature, both the far-infrared heater and the heating heater are continuously energized to rapidly raise the thawing temperature of the frozen food, and then, The intermittent energization rate of both heaters is the second. It drops to the third stage and the first stage. In the second stage, cold air is evenly supplied to the frozen food through the damper thermostat from the many ventilation holes provided in the reflector, suppressing the rise in surface temperature of the thawed food, and in the third stage, The damper thermostat is blocked and prevents the exhaust air from the thawing chamber from being collected by the cooler. Additionally, if you accidentally start defrosting without placing the food to be defrosted, if the second temperature sensor reaches the first predetermined temperature after a predetermined period of time, the power to both heaters will be stopped, and each part will become abnormally hot. It is prevented from becoming. Furthermore, after thawing,
By the temperature control action of the damper thermostat that operates at the second predetermined temperature of the second temperature sensor, the frozen food is automatically kept cold in a third temperature zone between the refrigeration temperature and the freezing temperature. become.

(Example) Hereinafter, an example of the present invention will be described in detail using FIGS. 1 to 6.

1 and 2 are a partially cutaway perspective view and a sectional view taken along the line B-B' of the thawing chamber, which is the main part of the present invention, respectively, and FIG. 3 shows an embodiment of the present invention. It is a side sectional view shown as a two-door refrigerator.

First, in FIG. 3, 8 is the refrigerator main body (hereinafter simply referred to as the main body), and the outer box 9. It consists of an inner box 10, and 11 is a heat insulating material between them.

The interior of the main body 8 is divided vertically into a freezing compartment 13 and a refrigerating compartment 14 by partition shelves 12. 15 is a thawing chamber located in one section of the refrigerator compartment 14, 16 is a refrigeration cycle compressor located at the rear of the bottom of the main body 8, and 17 is a cooler located at the back of the freezing compartment 13, which cools the air. The blower 18 blows the freezer compartment 13. Air is forced into the refrigerator compartment 14° and the thawing compartment 15. 19.20 is a damper thermostat.

FIG. 4 is a sectional view of the damper thermostat 20. 21 is an electromagnetic coil, 22 is a plunger 23 is a rod coupled to the plunger 22, and 24 is a damper that opens and closes the cold air passage.When the electromagnetic coil 21 is magnetized by electricity, the rod 23 is pushed up and the damper 24 is activated.
is opened and the current is cut off, the rod 23 falls and the damper 24 is closed. The damper thermostat 19 has the same configuration, and for convenience of explanation later, the electromagnetic coil of the damper thermostat 19 is designated 21', and the damper is designated 24''.

Returning to FIG. 3, 25 and 26 supply cold air from the blower 18 to the refrigerator compartment 14. The discharge ducts 27 and 28 introduced into the thawing chamber 15 are suction ducts for returning the cold air that has cooled the refrigerator compartment 14 and the thawing chamber 15 to the cooler 17, respectively. Further, 29 and 30 are temperature detectors in the freezing compartment 13° and the refrigerator compartment 14, respectively, and 31 is a second temperature detector for detecting the temperature in the thawing compartment 15.

The thawing chamber 15 is constructed as shown in FIGS. 1 and 2.

That is, in both figures, 32 is an outer box made of synthetic resin, 33 is a heat insulating material placed on its inner surface, and 34 is a far-infrared heater installed above the thawing chamber 15. A ceramic paint layer 37 containing silicon or the like as a main component is baked on and is configured to effectively radiate far infrared rays having a wavelength of about 577111 or more.

This far-infrared heater 34 is supported by a holder 38 made of synthetic resin with high heat resistance, hanging from a dome-shaped reflector plate 39 made of metal such as aluminum, as shown in the figure. It should be noted that the inner box part of the first reflecting plate 39, which constitutes both side walls and the back wall, is integrally formed in the thawing chamber 15, and a large number of ventilation holes 4o are formed in the flat part on both sides of the top dome part. . 41 is a bottom plate made of metal such as aluminum; 42 is a linear heater fixed to the bottom plate 41 in a thermally conductive manner;
Reference numeral 43 designates a first temperature sensor which is closely fixed near the center of the back surface of the bottom plate 41 in a thermally conductive manner. Reference numeral 944 designates a thawing plate that surrounds the outer periphery of a metal plate 46 on which the food to be thawed 45 is placed. It is composed of a frame body 47 made of synthetic resin. 48
49 is the front door of the thawing chamber 15, 5 is the protective net for preventing burns.
0 is a ventilation passage, which communicates with the damper thermostat 20 via a discharge port 51. Reference numeral 52 denotes a suction port formed in the back wall of the thawing chamber 15, and communicates with the suction duct 28. 53 is a defrost switch provided on the front surface of the main body 8.

FIG. 5 is a block diagram showing the electrical system of the above-mentioned refrigerator. Compressor 16. Blower18. Far infrared heater 34. The heaters 42 have relay contacts 54, 55, 56, respectively.
and 57 to the power supply E.

Furthermore, thawing chamber 15. The electromagnetic coils 21.21' of the damper thermostats 20.19 of the refrigerator compartment 14 are each connected to the power supply E via a relay contact 58.59.

60 is a temperature control device for the thawing chamber 15, which includes a temperature sensor 29 such as a thermistor. Resistor R□l R2, R31 Comparison circuit with comparator 61, transistor (hereinafter, transistor is abbreviated as Tr) 62. The output of the comparator 61 is connected to the base of the Tr 62, and the collector is connected to the suction relay coil 63 for opening and closing the relay contact 54. Similarly, 64 is a temperature control device for the refrigerator compartment 14, which includes a temperature sensor 30 such as a thermistor. Comparison circuit with resistor R4゜R5HRb + comparator 65, Tr66, relay coil 6
7, the output of the comparator 65 is connected to the base of the Tr 66, and the collector is connected to a suction relay coil 67 for opening and closing the relay contact 59. Furthermore, 68 is a temperature control device for the thawing chamber 15, and includes a second temperature sensor 31.68 such as a thermistor. Resistor R7, R,, R,
, and a comparator 69, the output of one of the comparators 69 is input to one of the OR circuits 70, and the output is applied to the base of the Tr 71 via the AND circuit 70a. Further, the collector of the Tr 71 has a suction relay coil 72 that opens and closes the relay contact 58.
is connected, and the output of the other comparator 69a is connected to the timer 90. AND circuit 79a via inverter 91
is connected to one input of the

73 is a thawing chamber control device, which controls the bottom plate 41 of the thawing chamber 15.
The first temperature sensor 43. Resistance R work. .

R11, R1□, a comparison circuit equipped with a comparator 74, and a timer? 5.76, 77, 77a, AND circuit 78
．． 79a, and OR circuits 80.81.82. OR circuit 70. Inverter 83. Tr84.85.86.
Relay coil 87.88.89° and defrost switch 5
It has 3. The output of the defrosting switch 53 then passes through a timer 75 to an AND circuit 78.798, an OR circuit 70.
82 are connected to one input of each of them.

The output of the comparator 74 is passed through the inverter 83 to the AN
is connected to the other input of the D circuit 78, and at the same time the A
connected to one input of the ND circuit 79;
The output of the AND circuit 77a is connected to one input of the OR circuit 80.81, and the output of the AND circuit 77a is connected to the timer 76, 77, 7.
9, and the outputs of timers 76 and 77 are connected to the input of O
It is connected to the other input of each of the R circuits 80 and 81. The collector of the Tr84.85 has a suction relay coil 87.8 that opens and closes the relay contact 56.57.
8 are connected. The output of the timer 77a is also the output of the OR circuit 70.

It is connected to one input of the AND circuit 70a.

Further, the output of the comparator 61 of the freezing room temperature control device 60 is connected to the other input of the OR circuit 82, and the output is connected to the base of the Tr 86, and its collector is used for suction to open and close the relay contact 55. relay coil 89
is connected.

When the timer 75 receives an H (high) level signal, it continuously outputs an H level signal for a predetermined time t, and then switches to an L (low) level signal.

Furthermore, while the H signal is being input to the inputs, the timers 76 and 77 alternately output H and L level signals for a predetermined period of time, but after the predetermined period of time has elapsed, the intermittent output rate of the H level signal becomes stepwise. Specifically, for example, the output of the timer 76 has an H level signal rate of 80% at the first time t, and 40% at the next time t2.
Similarly, the output of the timer 77 has an H level signal rate of 80% at the first time t□';
It is configured to be 0% at the next time t2.

Note that the operating time of the timers 76 and 77 is t1+j,=
t1'+t2', and the predetermined time t of the timer 75 is the operating time 11+J of the times 76 and 77, including the time-safe role of the defrosting action.
It is set to be sufficiently longer than =t□'+t2'.

Furthermore, the timer 77a normally outputs an H level, and -
Once an H level is input, it continues to output an H level for a time t□=t□, and then outputs an L level for a time t2=t2'.

The present invention is configured as described above and operates as follows.

(1) When the temperature of the freezer compartment 13 is higher than a predetermined value.

In this case, the resistance value of the temperature detector 29 is small and the output of the comparator 61 is at H level, so the Tr
62 is turned on and the relay coil 63 becomes conductive. Therefore, the relay contact 54 is closed and the compressor 16 is operated.
At the same time, since the output of the OR circuit 82 is also at H level, the Tr 86 is turned on and the relay coil 89 becomes conductive. Therefore, the relay contact 55 is closed and the blower 18 is also operated.
Freezer room 13. Refrigerator room 14. Cold air is forcedly blown into the thawing chamber 15 for cooling. Thereafter, when the freezer compartment 13 is cooled to a predetermined temperature, the resistance value of the temperature detector 29 increases and the output of the comparator 61 becomes L level. As a result, T
r62 is turned off, the output of OR circuit 82 also goes to L level, Tr86 is also turned off, and power to relay coils 63 and 69 is cut off. Therefore, both relay contacts 54, 55 are opened and compressor 16. The blower 18 stops. Thereafter, this operation is repeated and the inside of the freezer compartment 13 is maintained at a predetermined temperature, for example, -20°C.

(2) When the temperature of the refrigerator compartment 14 is higher than a predetermined value.

In this case, the resistance value of the temperature sensor 30 is small and the output of the comparator 65 is at H level, so T
r66 turns on and relay coil 67 becomes conductive. Therefore, the relay contact 59 is closed, the electromagnetic coil 21' is energized, and the damper 24' of the damper thermostat 19 is activated.
is opened, and cold air is introduced into the refrigerator compartment 14 for cooling. After that, when the refrigerator compartment 14 is cooled to a predetermined temperature,
The resistance value of the temperature sensor 3o increases, and the comparator 6
5 becomes L level, the Tr 66 is turned off, the power to the relay coil 67 is cut off, the relay contact 59 is opened, and the power to the electromagnetic coil 21' is also stopped.
The damper 24' of the damper thermostat 19 is closed to prevent cold air from flowing into the refrigerator compartment 14. From then on,
This operation is repeated and the inside of the refrigerator compartment 14 is maintained at a predetermined temperature 1, for example, -5°C.

(3) When the temperature of the thawing chamber 15 is higher than a predetermined value when not thawing.

In this case, the resistance value of the second temperature sensor 31 is small and the output of the comparator 69 is at the I] level, so the OR circuit 70. The output of the AND circuit 70a becomes H level, the Tr 71 is turned on, and the relay coil 72 becomes conductive. Therefore, the relay contact 58 is closed, the electromagnetic coil 21 is energized, the damper 24 of the damper thermostat 20 is opened, and cold air is introduced into the freezer compartment 15 for cooling. After that, when the freezer compartment 15 reaches a predetermined temperature, the resistance value of the second temperature sensor 31 increases, and the comparator 6
9 becomes L level, the output of OR circuit 70 becomes L level, the output of AND circuit 70a also becomes L level, Tr 71 is turned off, and relay coil 72
The power supply to the electromagnetic coil 21 is cut off, the relay contact 58 is opened, and the power supply to the electromagnetic coil 21 is also cut off. Then, the damper 24 of the damper thermostat 20 prevents the cold air from flowing into the blocked thawing chamber 15, and this operation is repeated thereafter, so that the inside of the thawing chamber 15 reaches a freezing temperature suitable for preserving a predetermined fresh food.
Temperature control is maintained in a third temperature zone between refrigeration temperatures, ie, a partial freezing temperature zone of about -3°C.

(4) When defrosting.

First, the food to be thawed 45 is placed on the thawing tray 44, placed on the bottom plate 41 of the thawing chamber 15, and the thawing switch 53 is turned on. Simultaneously with the input, the timer 75 outputs an H level signal, and one input of the AND circuit 78, 79a becomes H level. At this time, the bottom plate 41 of the thawing chamber 15 is, for example, -
The temperature is lowered by heat conduction with the thawing tray 44 on which the 20° C. frozen food 45 is placed, and the first temperature detector 43 is at a sufficiently low temperature. Therefore, the output of the comparator 74 is at the L level, and the signal inverted to the H level by the inverter 83 is input to the other terminal of the AND circuit 78. On the other hand, an L level signal is directly input to the AND circuit 79 without passing through the inverter 83. Therefore, AND
The outputs of circuits 78 and 79 are at H level and L level, respectively, timers 76 and 77 do not operate, and the OR
The outputs of circuits 80 and 81 become H level and T r84
, 85 are turned on, relay coils 87 and 88 are energized, relay contacts 56 and 57 are closed, and far infrared heater 34 is turned on.
．． The heater 42 is continuously energized. As a result, the thawing progresses and the first temperature sensor 43 detects a preset value, for example, 2.
When the temperature rises to 0°C (the time required for this is defined as t, and this period is called the first stage), the comparator 74
The output becomes H level, and a signal of L level is applied to the AND circuit 78 via the inverter 83, and its output becomes L level.

On the other hand, since the H level signal is applied to the AND circuit 79, the timers 76 and 77 start repeatedly outputting the 11th level and L level signals at a predetermined intermittent output rate, and the OR circuit at the corresponding intermittent output rate. 80.81 via T r84 ,8
5 is turned on and off, energization to relay coils 87 and 88 is interrupted, and relay contacts 56 and 57 are intermittently opened and closed. As a result, the far infrared heater 34 is continuously energized for the time t described above. At the time t□ following (this period will be called the second stage), the energization rate is 80%, and at the next time tz (this period will be called the third stage), the energization rate is 40%, The heat generation capacity is controlled to decrease in stages as time passes. In addition, the heater 42 has an energization rate of 80% during the time t1' following the continuous energization time t0, and the next time t2'.
is similarly controlled so that the heat generation capacity decreases to 0%.

In this way, the temperature of the food to be thawed 45 is low in the early stage of thawing.
far-infrared heater 34 until the temperature sensor 43 of . Since both heaters of the heater 42 are continuously energized, even if the weight of the food to be thawed 45 varies, the amount of heat generated is determined by the degree of temperature rise of the first temperature sensor 43 for a time appropriate for the weight. Thawing proceeds rapidly under conditions of large amounts, shortening the thawing time. After that, the heat generation capacity decreases stepwise with the passage of time, and the rise in the surface temperature of the food to be thawed 45 is suppressed, and thawing progresses.

During thawing, the far infrared heater 3
Radiation heating from 4 is performed evenly in conjunction with the reflection action of the reflecting plate 39, and heat conduction heating from the bottom surface by the heater 42 is performed at the same time. In heating with the far-infrared heater 34, far-infrared rays with a long wavelength of five or more units are radiated to the food to be thawed 45, so that the far-infrared rays can be efficiently used for general foods that have an absorption wavelength band in the far-infrared wavelength region. is absorbed and penetrates relatively far into the interior of the food to be thawed 45, and thawing progresses with less uneven thawing between the surface and the center. Further, by heating the heater 42, the bottom portion of the food 45 to be thawed, which is not sufficiently heated by the far-infrared heater 34, is thawed by heat transfer through the thawing plate 44.

On the other hand, during the above-mentioned decompression, that is, the output of the timer 75 is at H level. During the second and third stages, the output of the OR circuit 82 is at H level, the Tr 86 is turned on, and the relay coil 89 is conductive. Therefore, relay contact 5
5 is closed and the blower 18 is forcibly operated regardless of the output of the freezer compartment temperature control device 60, and the output of the timer 77a during that time is controlled by the comparator 74 in the first stage.
Since the output of is at L level, it is set to L level by the L level output of AND circuit 79. In the second stage that follows, A
When the output of the ND circuit 79 changes to H level, the timer 77a
The output of the AND circuit 70a is H level in the second stage and L level in the third stage, so the output of the AND circuit 70a is also
The stage becomes H level, the third stage becomes L level, and T
During that time, r71 turns on, on, and off. That is, during thawing, the damper 24 of the damper thermostat 20 for the thawing chamber is in the first position. In the second stage, it is forced to open, and in the third stage,
It is occluded at this stage.

As mentioned above, the first step. In the second stage, forced cold air is discharged from the open damper 24 by the blower 18 into the discharge duct 2.
6 from the discharge port 51 to the upper ventilation passage 50 in the thawing chamber 15
The cold air flows downward through a large number of ventilation holes formed in the reflecting plate 39, and uniformly cools the surface of the food 45 to be thawed.

In this way, the food to be thawed 45 is mainly affected by the far-infrared radiation effect of the far-infrared heater 34 and the control effect of the far-infrared heater 34 that gradually reduces the heat generating capacity, and the heating heater 42, as well as the surface temperature. This will suppress the increase in temperature, and as a result, thawing will proceed with a small temperature difference between the center and surface areas and less uneven thawing. After the end of the second stage when thawing has progressed considerably (for example, when the center temperature of the food to be thawed 45 is around -5°C), the damper 24 is forcibly closed by the damper thermostat 20 and cold air is not introduced. In addition, the defrosting process gradually progresses while the amount of heat generated by the heater is small. During this time, the temperature of the food to be thawed 45 is also rising, so the heating efficiency of the heater and the heat absorption efficiency of the food to be thawed 45 are decreasing, but since the damper 24 is in a closed state, the residual heat in the thawing chamber 15 remains. Since it is not recovered from the suction port 52, it is not returned to the cooler 17, and the amount of heat load on the cooler 17 is reduced accordingly, thereby freeing the compressor 16 from unnecessary operation.

FIG. 6 shows the temperature characteristics of the food 45 to be thawed during thawing and a time chart.

Furthermore, regarding the thawing time, due to the internal penetration effect of far infrared rays and continuous heating control in the initial stage of thawing, thawing can be done in a relatively short time, for example, 500 g of frozen tuna with a thickness of 25 Wm can be thawed in about 30 minutes. Further, the temperature of the reflecting plate 39, which is exposed in the ventilation passage 50 and would normally be at a considerably high temperature, is cooled and lowered, which is advantageous from a safety standpoint.

As described above, the first to third thawing times t. +t□+t
, =t,'+t□'+5', the timer 76,
At the same time, the output of timer 77 goes to L level, and is applied to the reset terminal of timer 76 to 75, and the output goes to L level. Therefore, T r84 and 85 are turned off, and the current to relay coils 87 and 88 is cut off. Then, the relay contacts 56 and 57 are opened, and the power supply to the far-infrared heater 34 and the heating heater 42 is cut off, and thawing is completed. At the same time, one input of the OR circuit 82 becomes L level, so that forced operation of the blower 18 is canceled.

Also, since the output of timer 77a returns to H level, A
One input of the ND circuit 77a becomes H level, and the forcibly closed state of the damper 24 of the damper thermostat 20 for the thawing chamber is released.

After the thawing is completed, the temperature of the thawing chamber 15 is controlled by the second predetermined temperature of the second temperature sensor 31, as in the case of normal cooling. Therefore, the thawed food 45 after thawing is approximately -3
It immediately stabilizes in the partial freezing temperature range of ℃, and the temperature does not rise further due to residual heat, and even if it is left as is, there is no need for the defroster to monitor and confirm that thawing is complete as in the past.

Thawed food is available at any time.

(5) If you start empty defrosting by mistake.

This is the case when the defrosting switch 53 is turned on without placing food to be defrosted. In this case, when the temperature of the second temperature sensor 31 continues to rise and exceeds the second set predetermined temperature 1, for example 3°C, and reaches the first set temperature, for example 40°C, the output of the comparator 69a becomes H level. Then, the timer 90 operates and outputs an H level signal after a predetermined time, and the L level signal inverted by the inverter 91 is sent to the AND circuit 7.
9a, its output becomes L level and is input to AND circuit 79, which outputs L level, so timers 76 and 77 do not operate, and one input of OR circuit 80.81 both has L level. level is input, and the other AND circuit 78 continues to output a level L signal, so level L is also applied to the other inputs of OR circuits 80 and 81, and both outputs are level L. Tr84.85
is turned off, energization to relay coils 87, 88 is cut off, relay contacts 56, 57 are opened, and energization to far-infrared heater 34 and heating heater 42 is stopped. That is, since both heaters are forcibly turned off when the temperature rises excessively, thermal deformation of each part of the defrosting chamber 15 is prevented.

(Effects of the Invention) As is clear from the above description, the present invention has the following effects.

(1) The food to be thawed is efficiently heated by far-infrared radiation heating from the top surface and thermal conduction heating from the bottom surface, and during thawing, the heat generating capacity is gradually reduced and the food is exposed to far-infrared rays. Combined with the effect of penetration into the interior of the thawed food, thawing can be achieved with extremely little unevenness in thawing between the center and the surface.

(2) The temperature sensor installed at the bottom of the thawing chamber continuously operates the far-infrared heater and heating heater until the predetermined temperature is reached, so even if the volume of the food to be thawed changes, the optimal maximum capacity can be achieved. Rapid freezing is achieved by heating.

(3) First. During the second stage of thawing, the damper thermostat for the thawing chamber is forcibly opened.

Since the blower is operated to bring cold air down and in through the ventilation path in the space on the back side of the reflector, the surface of the food to be thawed is evenly cooled, temperature rise is further suppressed, and thawing with less unevenness is possible.

(4) Since the damper thermostat is forcibly closed during the third thawing stage, residual heat in the thawing chamber is not returned to the cooler and does not become a heat load. Therefore, extra cooling operation of the compressor can be reduced.

(5) Since the reflector plate and other peripheral components are exposed to the ventilation path during thawing and are cooled, the temperature decreases and is safe.

(6) If an excessive rise in temperature occurs, both the far-infrared heater and heating heater are forcibly turned off, thereby preventing thermal deformation of various parts of the thawing chamber.

(7) After thawing, the third temperature between the thawing room and the refrigerator room temperature.
For example, since it is cooled to the partial freezing temperature range of approximately -3℃, the temperature of the thawed food will not rise further due to residual heat immediately after thawing, and the freshness of the thawed food will be lost even if left as is. No food available at any time.

[Brief explanation of drawings]

Fig. 1 is a partially cutaway perspective view of a main part of a freezer compartment according to an embodiment of the present invention, Fig. 2 is a sectional view taken along line BB' in Fig. 1, and Fig. 3 is a perspective view of a refrigerator according to an embodiment of the present invention. 4 is a sectional view of the main part of the damper thermostat, and FIG. 8 is a sectional view taken along line A-A' in FIG. 7, which is a perspective view of the box. 15... Thawing chamber, mostat, material, 34... -ta ray, 36 Tsuku paint layer, air hole, 41... ri, 43... 19.20 ・ 32... outer box, far infrared heater ,...Glass tube, 37 39...Reflector, bottom plate, 42...First temperature detector, damper 33...Insulation 35...Heat...ceramic 40...Thread Heating heat thawing dish, 45... Food to be thawed, 48... Protective net, 5
0... Ventilation duct, 51... Discharge port, 5241. Suction port, 53... Defrost switch.

Claims (1)

[Claims] A far-infrared heater having a reflector plate with a dome-shaped ventilation hole covering the back is provided at the top, and a thawing tray for food to be thawed having a heating heater and a first temperature sensor at the bottom. A thawing chamber is provided with a second temperature sensor, and a ventilation passage formed on the back surface of the reflector plate is opened via a damper thermostat to adjust the amount of cold air inflow. During thawing, the blower is forcibly operated to connect the ventilation path to the freezer compartment, and the far-infrared heater and the heating heater are operated so that the temperature of the first temperature sensor on the bottom part increases from the start of thawing. The energization rate of the far-infrared heater and heating heater is gradually reduced by operating continuously until a predetermined temperature is reached as the first stage, and thereafter operating intermittently as the second and third stages, and In the second stage, the damper thermostat is forcibly opened, and in the third stage, it is forcibly closed, and when the temperature of the second temperature sensor reaches the first predetermined temperature after a predetermined time, the far-infrared heater and By discontinuing the energization of both heaters, and by bringing the temperature of the second temperature sensor to the second predetermined temperature when not defrosting,
An electric refrigerator characterized in that the thawing chamber is maintained in a third temperature range between the refrigerating temperature and the freezing temperature.