JPH0787767B2 - Defroster - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to a thawing device having a function of thawing food without causing an unfavorable temperature rise that adversely affects food or the like.

[0002]

2. Description of the Related Art Thawing devices such as thaw boxes for thawing frozen meats, seafood, vegetables, fruits and other foods and the like are well known. Conventionally, when the thawing heater is continuously energized to perform thawing during the thawing operation of such a thawing device, when all the food is completely thawed, the temperature of some foods is too high and is adversely affected. There is a certain width in the hot air set temperature from and the switch of the defrosting heater is turned on and off at the upper and lower limits of this width so that the temperature of the hot air blown from the hot air circulation fan does not rise too high. Was being controlled.

[0003]

However, in this case, since the suction temperature of the warm air circulation fan is not stable, the same defrosting end temperature cannot always be detected, and there is a variation in the defrosting time control. There was a flaw. The present invention has been proposed in order to appropriately improve the above in view of the above-mentioned drawbacks inherent in the defrosting device according to the conventional technique, and suppresses an unnecessary temperature rise of foods, It is an object of the present invention to provide a thawing device capable of thawing the frozen food in the refrigerator at a uniform temperature every time.

[0004]

In order to achieve the above object, a housing defining a storage space for articles to be defrosted, heat generating means (heater for thawing) for heating air in the housing, According to the present invention, a thawing device provided with a circulation fan for circulating the air heated by the heat generating means so as to flow through the storage space is arranged on the air outlet side of the circulation fan, Of the outlet air of the circulating fan, and a first detecting means for outputting a first detection signal indicating the temperature, and the temperature of the inlet air to the circulating fan, which is arranged on the air inlet side of the circulating fan. And a second temperature detecting means for outputting a second detection signal representing the temperature, and the first and second temperature detecting means connected to receive the first and second output signals, respectively, to output from the circulation fan. The exit sky Temperature is substantially a control unit that controls the decompressor to be constant.

[0005]

When the heat generating means (heater for thawing) is urged to start thawing and the internal circulation fan is driven, the air in the housing passes through the storage space from the air outlet side (air outlet) of the circulation fan. It reaches the air inlet side (suction port). These outlet air and inlet air are respectively measured by the outlet temperature sensor (first
The temperature is detected by a temperature detecting means) and a suction port temperature sensor (second temperature detecting means). At the time of thawing, the air temperature on the air outlet side gradually rises, but the thawing heater is controlled so that the air temperature is almost constant and is turned on / off, and eventually reaches a substantially constant value (No. 8). (See curve N in the figure). In this way, since the temperature of the air on the outlet side that flows into the storage space is almost constant, when the air flows through the storage space and reaches the air inlet side, the air temperature continues to increase gradually and eventually. The thawing end temperature is reached (see curve P in FIG. 8). Therefore, the frozen food in the refrigerator is thawed stably at a uniform temperature every time.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of a thawing / refrigerating machine as a thawing apparatus according to the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 schematically shows an embodiment of a thawing / refrigerating machine according to the present invention. The thawing / refrigerating machine has a box-shaped main body (housing) 12 having a heat insulating material. A thawing heater (heat generating means) 7 and an internal circulation fan 9 are provided. The internal circulation fan 9 sends an air flow through the inside of the duct 10 during its operation, and circulates the air flow in each storage space 11a between the shelves 11 as shown by an arrow. An appropriate portion of the duct 10 on the discharge side of the circulation fan 9 (hereinafter referred to as an airflow outlet)
Is provided with an outlet temperature sensor (first temperature detecting means) 13, and the air outlet side of the space 11a, that is, the suction side of the circulation fan 9 is preferably the uppermost portion of the shelf 11 (hereinafter referred to as the uppermost portion). , Suction port) and a suction port temperature sensor (second
Temperature detecting means) 14 is provided, and the outlet temperature sensor 13 and the inlet temperature sensor 14 are connected to a control circuit or a control device 17.

An evaporator 6 is fixedly mounted in a well-known manner above the shelf 11 in the main body 12. The evaporator 6 is connected to the compressor 1, the condenser 3, the dryer 4 and the capillary tube 5 as shown in the figure, and cooperates with them to form a known cooling system.
Reference numeral 2 is a cooling fan of the condenser 3. Further, the above-mentioned thawing heater 7 is installed between the evaporator 6 and the uppermost shelf 11 and is connected to the protective thermostat 8. The above-described compressor 1, defrosting heater 7 and protective thermostat 8 are also connected to the control circuit 17. A defrosting start switch 15 for switching a refrigerating mode / defrosting mode, which will be described later, and a defrosting mode display lamp 16 which is turned on at the time of defrosting are connected to the control circuit 17.
Receives signals from the outlet temperature sensor 13 and the inlet temperature sensor 14, and depending on the setting of the refrigerating mode / defrosting mode, the compressor 1, the cooling fan 2, the thawing heater 7, the internal circulation fan 9, etc. A control signal is output to the control unit to control the thawing and refrigerating operations in this manner. In this embodiment, the defrosting start switch 15 is a momentary type push button, which is turned on when pressed and turned off when released. However, if this defrosting start switch 15 is pressed once,
The control circuit 17 remains in the defrosting mode even when the hand is released, and the defrosting mode display lamp 16 continues to light to indicate the defrosting mode. When the defrosting mode ends, the control circuit 17 automatically enters the refrigeration mode. Control to move.

Next, the operation will be described with reference to FIG.
First, in the refrigerating mode, the thaw / refrigerator of FIG. 1 works as a refrigerator, and in the thaw mode, it works as a thaw cabinet. Evaporator 6 in the cooling system when in refrigeration mode
The air cooled by the heat exchange with the air is blown into the inside of the store by the inside circulation fan 9 through the duct 10 to cool the food and the like placed on the shelves 11 inside the store, and then to the evaporator 6 from the suction port. Return. Here, the control circuit 17 turns on the compressor 1 and the cooling fan 2 in accordance with a signal from the suction port temperature sensor 14 attached to the suction port so that the inside of the refrigerator has a predetermined refrigerating temperature having a predetermined temperature range. / Turn off. FIG. 2 shows the control mode at this time, that is, the relationship between the inlet temperature in the refrigerator and the ON / OFF operations of the compressor 1 and the cooling fan 2. In FIG. 2, the vertical axis represents the inlet temperature tr and the horizontal axis represents the time t.
Tc is the set refrigerating temperature, Ta is the lower limit temperature in the refrigerator, Tb is the upper limit temperature in the refrigerator, td ₁ is the temperature range in the refrigerator, and td ₁ = Tb−T
a. The corrugated lines shown below the table indicate the cooling system on / off, with on indicating that the compressor 1 and cooling fan 2 are operating together, and off indicating that they are both stopped. As shown in FIG. 2, when the suction port temperature sensor 14 detects the lower limit temperature Ta in the refrigerator, the cooling system is turned off, and thereafter, when the internal temperature rises and the upper limit temperature Tb in the refrigerator is detected, the cooling system is turned off. The cooling system is turned on again, and thus the internal cold storage temperature is maintained between the internal cold storage lower limit temperature and the internal cold storage upper limit temperature.

Next, when the defrosting start switch 15 is turned on, the defrosting mode is set and the defrosting mode display lamp 16 is turned on. In the thawing mode, first, the temperature of the outlet is controlled so as to keep the outlet temperature constant as will be described later (Fig. 5 to Fig. 8). Regarding the temperature of the suction port, when the suction port temperature sensor 14 detects a temperature equal to or lower than a predetermined thawing start temperature, the thawing heater 7 is energized, and then the inside of the refrigerator is warmed to thaw higher than the thawing start temperature. When the end temperature is detected, the thawing mode is ended and the refrigeration mode is automatically controlled. When the thawing start switch 15 is turned on to set the thawing mode, and the temperature detected by the suction port temperature sensor 14 is higher than the thawing start temperature, the cooling system is kept energized to continue the refrigerating operation, and the thawing start temperature is detected. At that point, the cooling system is deactivated and the thawing heater is activated.

The control mode at this time will be described with reference to FIGS. 3 and 4. FIG. 3 shows the case where the temperature detected by the suction port temperature sensor 14 is higher than the thawing start temperature when the thawing mode is set by the thawing start switch 15,
The figure shows the low case. In FIGS. 3 and 4, the vertical axis represents the inlet temperature tr detected by the inlet temperature sensor 14, and the horizontal axis represents the time t. Also, Ts represents the thawing start temperature, and Te represents the thawing end temperature. Suction port temperature t
In the waveform representing the relationship between r and time, the solid line shows the defrosting operation and the dotted line shows the refrigerating operation. 16 indicates that the lamp is on, and off indicates that the refrigerating mode, that is, the defrosting mode indicating lamp 16 is off. Also, td ₂ is t
d ₂ = Te−Ts ≧ 0.

In FIG. 3, when the thawing start switch 15 is turned on at the point A higher than the thawing start temperature Ts to enter the thawing mode, the thawing heater 7 is not energized even in the thawing mode and the refrigerating operation continues. To be Therefore, the temperature t
When r decreases to point B and the suction port temperature sensor 14 detects the defrosting start temperature Ts, the cooling system is deactivated and the defrosting heater 7 is energized to start the defrosting operation. After that, when the temperature in the refrigerator rises and the suction port temperature sensor 14 detects the defrosting end temperature Te at the point C, the defrosting mode ends, the defrosting heater 7 is deactivated, and the cooling system is automatically energized. Then the cooling mode is entered. In FIG.
Defrosting start switch 15 at point D lower than the defrosting temperature Ts
When is turned on, the thawing heater 7 is immediately energized to start the thawing operation. After that, when the thawing end temperature Te is detected at the point E, the thawing mode ends and the refrigerating mode is automatically entered.

In the present invention, as described above, during the thawing operation, the thawing heater 7 is proportionally controlled so that the air outlet temperature obtained from the air outlet temperature sensor 13 attached to the air outlet is constant, and the refrigerator is kept in the storage. It operates to thaw things placed on shelves 11 therein. Therefore, in order to compare this operation with the conventional operation, FIGS. 5 to 8 are used for the case where the control for keeping the outlet temperature constant according to the present invention is performed and the case where the conventional control for keeping the temperature constant is not performed. Explain.

FIG. 5 is a diagram showing the relationship between the outlet port temperature and the inlet port temperature and the temperature of the food to be thawed when the thawing heater 7 is continuously energized according to the prior art. FIG. 6 is a diagram showing the respective temperatures when the defrosting heater 7 is proportionally controlled so that the outlet temperature becomes constant according to the present invention. 5 and 6, the vertical axis is temperature, the horizontal axis is time t, a and f are outlet temperatures, e and k are inlet temperatures, Te is the set defrosting end temperature, To.
Is the set proportional control temperature, b and g are the temperatures of foods, etc. that can be thawed quickly, c and i are the temperatures of foods, etc. that are thawed at a standard speed, and d and j are the temperatures of foods that are thawed slowly. Is. In FIG. 5, when the thawing heater 7 is continuously energized, the outlet temperature rises as the thawing progresses, but in the case of foods or the like where the thawing proceeds rapidly, the thawing ends as shown by the curve b. At times, the temperature becomes considerably high, and foods and the like are likely to be adversely affected. In this regard, in FIG. 6, since the thawing heater 7 is controlled and the outlet temperature is constant, the temperature of food or the like does not rise above the outlet temperature even near the end of thawing. Is hard to come out.

Next, referring to FIG. 7, a case of controlling the outlet temperature of the prior art with a temperature range will be described, and referring to FIG. 8, a case of controlling according to the present invention will be described. As in FIGS. 5 and 6, the vertical axis represents temperature, the horizontal axis represents time t, and Te represents the thawing end temperature. Further, L and N indicate the outlet temperature, and M and P indicate the inlet temperature. In FIG. 7, if the outlet temperature is controlled with a temperature range and there is a variation as shown by the curve L, the inlet temperature M also varies. When the temperature is near the thawing end temperature Te, the thawing end point greatly changes to F point or G point due to a slight difference in the suction port temperature M, and the thawing end temperature Te cannot be stably detected. In, the suction port temperature P monotonically increases, and the defrosting end point can be stably detected at point H.

FIG. 9 is a block diagram showing an embodiment of the internal circuit of the control circuit 17 shown in the block diagram of FIG. 1 for performing the operation described above. In the figure, 20 indicates a circuit portion that controls the operation in the refrigerating mode, and 30 indicates a circuit portion that controls the operation in the defrosting mode. In the refrigerating mode, a voltage signal representing the set refrigerating temperature Tc in FIG. 2 is set in the refrigerating temperature setting circuit 21.
The first comparator 22 is a window comparator, and the comparator 22 includes a signal indicating the set refrigerating temperature Tc from the refrigerating temperature setting circuit 21 and the suction port temperature sensor 1.
4, the temperature signal converted into the voltage through the temperature detection circuit 23 is input, and the suction port temperature has a predetermined temperature range td ₁ (second
As shown in the figure), a signal for activating or deactivating the cooling system is output at the upper limit temperature Tb in the refrigerator and the lower limit temperature Ta in the refrigerator. The signal from the first comparator, via gate 24 and compressor driver 25, energizes compressor 1. Here, only the compressor 1 is representatively shown as the cooling system. In the refrigerating mode, the defrosting start switch 15 is not turned on, and the defrosting / refrigerating mode control circuit 26 outputs the refrigerating operation signal to the gate 24, which causes the gate 24 to output the signal from the first comparator 22. Can be threaded.

When the thawing start switch 15 is turned on to enter the thawing mode, first the thawing / refrigerating mode control circuit 26
Outputs a lamp lighting signal to the defrosting mode display lamp 16, and the lamp is lit. In the outlet temperature setting circuit 31, the proportional control temperature To shown by the curve f in FIG. 6 and shown by the curve N in FIG. 8 is set. The signal from the outlet temperature sensor 13 is the temperature detection circuit 3
In step 2, the voltage signal is converted into a voltage signal and given to the amplifier circuit 33. The amplifier circuit 33 amplifies the detected voltage signal from the temperature detection circuit 32 with reference to the voltage signal from the outlet temperature setting circuit 31. The amplified signal s is obtained by applying the amplified signal to the second comparator 34. The amplified signal s is supplied to the temperature sensor 13
This is a signal in which the voltage increases as the temperature detected at rises.

The second comparator 34 has an oscillator 3 which serves as a reference signal source for the second comparator 34.
The signal r from 4'and the amplified signal s from the amplifier circuit 33 are compared. The reference signal r from the oscillator 34 'is, for example, 1
A sawtooth wave of Hz (a triangular wave may be used) is applied with a DC bias. When the reference signal r is larger than the amplified signal s from the amplifier circuit 33, the second comparator 3
The output signal w of 4 is a signal for turning on the defrosting heater 7, and when it is small, it is a signal for turning off the defrosting heater 7. Therefore, the waveform shown on the output side of the second comparator 34 in FIG. As is further understood from the above, in the portion where the amplified signal s from the amplifier circuit 33 and the reference signal r from the oscillator 34 'overlap, a signal for turning on / off the defrosting heater for a period according to the degree of the overlap. Is output (see the waveform w shown on the output side of the second comparator 34 in FIG. 9). During thawing, the amplified signal s usually starts from a low value and rises until it stabilizes at a suitable position in this overlap. Here, the temperature at which the off signal starts to be output, that is, the outlet temperature when the magnitude of the amplified signal s from the amplifier circuit 33 matches the lower limit of the sawtooth wave, and the temperature at which only the on signal starts to be output, that is, the amplified signal The difference from the outlet temperature when the magnitude of s matches the upper limit of the sawtooth wave is set to about 1 ° C. In this way, the signal w for proportionally controlling the thawing heater 7 is output from the output of the second comparator 34.

The signal w from the second comparator 34 is given to the gate 35, and when the gate 35 receives the defrosting operation signal from the defrosting / refrigeration mode control circuit 26, the signal is further passed to the heater driver 36. Then, the thawing heater 7 is energized. Also, the signal from the outlet temperature setting circuit 31 is the bias circuit 3 for generating the thawing start / end temperature.
Also given to 7. The thawing start / end temperature generating bias circuit 37 is based on the signal indicating the set temperature from the outlet temperature setting circuit 31, and is a temperature lower by a predetermined temperature than that (in the case of FIG. 8) or the same temperature ( A signal representing (in the case of FIG. 6) is output to the third comparator 38.
The third comparator 38 is a window comparator, and based on a signal from the defrosting start / end temperature generating bias circuit 37, sets the lower limit of the window to the thawing start temperature T.
s, the upper limit is set as the thawing end temperature Te. That is,
From the inlet temperature sensor 14 through the temperature detection circuit 23 to the third
If the voltage signal input to the comparator 38 is equal to or higher than the lower limit of the window, the third comparator 38 outputs the refrigerating operation signal, so that the defrosting / refrigerating mode control circuit 26 outputs the refrigerating operation signal to the gate 24. When the circuit portion 20 performs the refrigerating operation and then the voltage signal becomes equal to or lower than the lower limit of the window, the third comparator 38 outputs the defrosting operation signal, so that the defrosting / refrigerating mode control circuit 26 defrosts the gate 35. When the voltage signal reaches the upper limit of the window by outputting the operation signal and the circuit portion 30 performs the defrosting operation, the third comparator 38 also outputs the refrigeration operation signal, and the circuit portion 20 performs the refrigeration operation. . At the stage of entering the refrigerating operation, the defrosting mode display lamp 16 is turned off.

When the thawing / refrigerating mode control circuit 26 enters the refrigerating operation after finishing the thawing operation once, even if the suction port temperature sensor 14 becomes the lower limit of the window after that, the thawing operation is no longer performed. That is, the thawing / refrigerating mode control circuit 26 turns on the thawing start switch 15 and then
Decompress only once. As described above, referring to FIG.
However, it should be noted that various circuits are conceivable for implementing the operation of the control circuit 17.

[0020]

According to the present invention, since the thawing heater (heat generating means) is controlled by the outlet temperature sensor (first temperature detecting means), the outlet temperature can be kept substantially constant. ,
As a result, an unnecessary temperature rise of the air flowing through the storage space can be avoided, so that a thawing device that does not adversely affect foods or the like is provided. In addition, since the outlet temperature is kept substantially constant as described above, the change in the inlet temperature increases monotonically and stabilizes. Therefore, by observing the inlet temperature, the defrosting is stable with good reproducibility. It is possible to detect the end temperature.

[Brief description of drawings]

FIG. 1 is a schematic elevational view showing a partial cross-section of an embodiment in which the present invention is applied to a refrigerator that also serves as a thawing device.

FIG. 2 is a timing chart for explaining the temperature change in the refrigerator and the refrigerating operation in the refrigerating mode when the defroster is operated according to the present invention.

FIG. 3 is a timing chart for explaining the temperature change in the refrigerator and the thawing operation in the thawing mode when the thawing apparatus according to the present invention is operated when the temperature detected by the suction port temperature sensor is higher than the thawing start temperature. It is a chart.

FIG. 4 is a timing chart for explaining the temperature change in the refrigerator and the thawing operation in the thawing mode when the thawing apparatus according to the present invention is operated when the temperature detected by the suction port temperature sensor is lower than the thawing start temperature. It is a chart.

FIG. 5 is a timing chart for explaining the operation of the defrosting mode of the conventional defroster / refrigerator in which the defrosting heater is continuously energized.

FIG. 6 is a timing chart for explaining the operation of the thaw / refrigerator thaw mode when the thaw heater is proportionally controlled so that the outlet temperature is constant according to the present invention.

FIG. 7 is a timing chart for explaining the operation of the conventional thawing and thawing mode in the refrigerator when the outlet temperature is controlled with a temperature range.

FIG. 8 is a timing chart for explaining the operation of the thaw / refrigerator thaw mode when the outlet temperature is monotonically increased according to the present invention.

FIG. 9 is a block circuit diagram showing an example of the control circuit shown in FIG. 1 used when operating the defroster according to the present invention.

[Explanation of symbols]

7 ... Defrosting heater (heat generating means), 9 ... Circulation fan, 1
1a ... storage space, 12 ... housing, 13 ... outlet temperature sensor (first temperature detecting means), 14 ... inlet temperature sensor (second temperature detecting sensor), 17 ... control circuit (control device), s ... first Detection signal.

Claims (1)

[Claims] 1. A housing (12) which defines a storage space (11a) for storing articles to be defrosted, a heat generating means (7) for heating air in the housing (12), and the heat generating means.
The air heated by (7) is used for the storage space (11
a) a thawing device provided with a circulation fan (9) for circulating so as to flow through it, the temperature of outlet air from the circulation fan (9) being arranged on the air outlet side of the circulation fan (9); And a first detection means (13) for detecting a temperature and outputting a first detection signal (s) indicating the temperature, and an air inlet side of the circulation fan (9), which is disposed on the air inlet side of the circulation fan (9). Second temperature detecting means for detecting the temperature of the inlet air and outputting a second detection signal
(14) is connected to the first and second temperature detecting means (13, 14) to receive the first and second detection signals, respectively, and the temperature of the outlet air from the circulation fan (9) is almost the same. A decompression device, comprising: a control device (17) for controlling the decompression device so as to be constant.