JPS6317316A - Defreezing device - Google Patents

Abstract

PURPOSE:To eliminate a deteriorated nature of a surface of a defreezed product and shorten a defreezing time by a method wherein a heater driving control circuit is constructed such that an upper limit temperature and a lower limit temperature are set higher at the beginning of defreezing condition and set lower in subsequent to the higher temperature. CONSTITUTION:Each of temperature discriminating circuits 15, 16 and 17 having different upper limit temperature reference value for shutting a heater 9 and lower limit temperature reference value for energizing the heater 9 is selected in sequence at the beginning of defreezing operation and made effective through a timer circuit 33, etc., thereby a heater driving control circuit 13 is constructed such that the upper limit temperature reference value and the lower limit temperature reference value are increased at the beginning of defreezing time, for example, a time T1 and then gradually decreased at a time T2 and a time T3. Therefore, at the beginning of defreezing in which a temperature of the defreezed item itself is low and a nature at the surface is not varied, an energization time of the heater 9 can be extended, a heating calorie for the defreezed item can be increased, thereby a high temperature can be attained to an extent that a varied nature at the surface of the item is not generated within a short period of time at the beginning of defreezing operation and the defreezing time can be shortened. Thereafter, the upper and lower limit temperature reference values are decreased in sequence in two steps and a defreezing can be performed without generating any varied nature of the surface part.

Description

DETAILED DESCRIPTION OF THE INVENTION [Invention] (Industrial Application Field) The present invention relates to a thawing device that thaws an object by controlling power on/off of a heater based on temperature detection of the object. .

(Prior Art) Conventionally, in a thawing device such as a refrigerator, a thawing chamber is provided inside the thawing chamber, and a heater for heating the object to be thawed and a heater for supplying cold air to the object to be thawed have been installed inside the thawing chamber. In addition to providing a fan for blowing air, a temperature sensor is provided to detect the temperature of the object to be thawed, and a heater drive control circuit is further provided to control power on/off of the heater based on the temperature detected by this temperature sensor. is provided.

In this device, after the object to be thawed is stored in the thawing chamber, thawing of the object to be thawed is started by turning on the thawing set switch.In this case, while driving the fan, The crystallinity sensor detects the temperature of the object to be thawed, and when the detected temperature value is below the lower limit temperature reference value set in the heater drive control circuit, the heater is energized, and when the upper limit temperature reference value is reached, the heater is turned off. control so that it is powered.

In this case, the item to be thawed is blown with cold air by a fan and also heated by a heater, so unlike the thawing method using 111 fans, the thawing time is shorter, but the following problem arises: there were. In other words, when heating an object to be thawed by a heater, there is a risk that the heater may be continuously energized due to temperature detection instability factors such as variations in the detection operation of the 13 degree sensor or changes in ambient temperature. If the temperature of the outside becomes too high compared to the inside temperature, the surface of the object to be thawed may be over-thawed, resulting in deterioration of the back surface. In order to prevent such deterioration of the back surface of the object to be thawed, conventionally, the lower limit temperature reference value and upper limit temperature reference value (H) in the heater drive control circuit are set low to increase the chances of the heater being turned off. ing. However, this still leaves a problem in that the effect of shortening the thawing time by using the heater is not so great.

(Problems to be Solved by the Invention) As mentioned above, when a heater is used to defrost an object, there is a problem in that the time required for thawing cannot be reduced significantly if the deterioration of the back side of the object is to be eliminated. was there.

The present invention has been made in view of the above circumstances, and its objective is to provide a thawing device that can reduce the required time while eliminating deterioration of the back surface of the object to be thawed.

[Structure of the Invention] (Means for Solving the Problems) The present invention provides a heater for heating an object to be thawed stored in a thawing chamber, an H degree sensor for detecting the temperature of the object to be thawed, and a temperature sensor for detecting the temperature of the object to be thawed, and A heater drive control circuit based on a temperature sensor (turns off power to the heater when the detected temperature value rises to an upper limit temperature reference value, and energizes the heater when the temperature detection value falls to the lower limit temperature reference value to drive and control the heater. The heater drive control circuit is configured such that the upper limit temperature reference value and the lower limit temperature reference value are high at the beginning of thawing and then become low.

(Function) When thawing is started in L in which an object to be thawed at a frozen temperature is housed in the thawing chamber, the heater is energized because the object to be thawed is lower than the lower limit reference temperature at the beginning of the thawing process. I get a fever. The heat generated by this heater heats the object to be thawed, raising its temperature, but since the limit temperature and lower limit reference temperature are high, the temperature detected value based on the temperature sensor is the lower limit la degree reference value. Therefore, there are fewer chances of power outage to the heater, and the heater is energized exclusively, resulting in a short power outage time.
The amount of heating for the object to be thawed becomes large. In this case, since the temperature of the object to be thawed is low at the beginning of thawing, even if the amount of heating to the object is large, the surface and interior of the object will reach a temperature that does not cause deterioration of the back side. rises within a short period of time.

After this, the 1-limit crystallinity standard value and the lower limit temperature standard value become lower, and the temperature of the thawed object rises from the initial stage of thawing. The temperature difference between the temperature difference and the lower limit temperature reference value becomes smaller, the chances of electricity cutoff to the heater increase, the energization time decreases, and the electricity cutoff time becomes longer, and while the 1g degree rise on the surface of the object to be thawed is suppressed, the overall temperature increases. The temperature rises, and the object to be thawed is thawed in a short time without causing deterioration of the back side.

(Example) An example in which the present invention is applied to a defrosting device for a refrigerator will be described below with reference to the drawings.

First, in FIG. 2, reference numeral 1 is a refrigerator main body, and inside the refrigerator main body 1, a thawing chamber 3 and a refrigerator compartment 4 are separated by a partition wall 2.
A partition is formed under -1-. In addition, 1- of thawing chamber 3
Although not shown, a freezing chamber is formed in the blade portion. 1-Cold air is supplied to the thawing chamber 3 and the refrigerating chamber 4 from a cold air supply duct (not shown). 5 and 6 are vents formed in the front and rear parts of the partition wall 2 to communicate the thawing chamber 3 and the refrigerator compartment 4, and 7 is a chilled case disposed above the thawing chamber 3.

Now, 8 is a thawing plate placed at the bottom of the thawing chamber 3,
As shown in FIG. 3, a heater 9 is attached to the back surface of the defrosting plate 8, and a temperature sensor 10 consisting of a negative characteristic thermistor is attached. Reference numeral 11 represents a fan disposed within the thawing chamber 3, and reference numeral 12 represents a fan drive motor for driving the fan 11. L', the heater 9 detects the temperature of the temperature sensor 10 and controls the heater drive control circuit 13 (first
(see figure), and the fan drive motor 12 is also driven at the time of defrosting.

Next, the heater drive 1; 11 control circuit 13 will be explained with reference to FIG. The detected temperature value Ek corresponding to the voltage is output as a voltage level.

15, 16 and 17 are respectively 1st and 2nd. The first temperature determination circuit 15, which is a third temperature determination circuit, is composed of a reference voltage generation circuit 18 that generates a basic voltage as a temperature reference value Ets, and a comparator 19. The temperature reference value E18 from the reference voltage generation circuit 18 is given to the inverting input terminal (+), and the temperature detection value Ek from the temperature detection circuit 14 is given to the inverting input terminal (-).
is given. Also, this comparator 19 provides hysteresis in the rising and falling edges of its output, that is, the upper limit of 1g degree J! Standard value Etsh and lower limit FA a base value E1.
(is created. Therefore, comparator 19
Ha l! When the temperature detection value Ek from the i degree detection circuit 14 rises to the upper limit temperature reference value EISh, the output signal St is changed to low level, and the lower limit temperature J! $ value E
When the voltage drops to 16', the output signal StS is changed to 1 level. The second temperature determination circuit 16 and the third
The temperature judgment circuit 17 also changes to -1? It has the same configuration as the first temperature rR71 constant circuit 15, and the second temperature determination circuit 16
is a base voltage generation circuit 20 that generates a base voltage as a temperature reference value E20 and a comparator 2 having hysteresis.
1, and the third temperature determination circuit 17 includes a reference voltage generation circuit 2 that generates a reference voltage and a temperature reference value E22.
2 and a comparator 23 having hysteresis. However, each temperature judgment circuit 15, 16 and 17
Temperature reference value E18. E20 and E2□ are El
It is determined that B > E20 > E22,
That is, the upper limit temperature base a value E1. h and the lower limit temperature reference value IS', the upper limit temperature reference value E16h and the lower limit temperature reference value 16 in the second temperature determination circuit 16 (and the upper limit temperature reference value El, h and the lower limit in the third temperature determination circuit 17). As shown in FIG. 4, the temperature reference values 17 (temperature reference values 17) are set to decrease in that order.
The temperature width between the upper limit temperature reference value and the lower limit temperature reference value in 6 and 17 (the hysteresis width of each comparator) is
As shown in the figure, the values are set in decreasing order. Reference numeral 25 denotes an input circuit comprising a defrost set/reset switch 26 consisting of an automatic return type bushing switch, a Schmitt trigger inverter 27, etc., which outputs its output signal by turning on the defrost set number reset switch 26. S25 (output signal from inverter 27) is changed to high level, and the output signal is applied to clock terminals CK of D flip-flop circuits 28, 29 and 30. The D flip-flop circuits 28, 29 and 30 have clock terminals C when their reset terminals k are in a high level state.
When the signal applied to K changes to high level, it is set by the rise of the signal, and changes the set output terminal Q to the level of the data terminal. Then, when the signal applied to the reset terminal trap changes from high level to low level, the reset circuit changes the set output terminal Q to low level as the signal falls. 31 is a reset circuit configured with a resistor, a capacitor, and a Schmitt trigger inverter, which outputs an output signal S3 when the power is turned on.
1 to low level and reset @Tk of each flip-flop circuit 28, 29, and 30 to high level, and when the power is turned off, each flip-flop circuit 2
8.29 and 30, and is also used to compensate for instantaneous power outages. 32 is an oscillation circuit which outputs a moving vehicle frequency pulse. Reference numeral 33 denotes a timer circuit configured to have a frequency dividing function, and when the signal applied to the reset terminal R changes from low level to high level, the rising edge of the signal is applied to the clock terminal CK from the oscillation circuit 32. Counting is started based on the base frequency pulse. As can be seen from FIG. 5, this timer circuit 33 changes the output terminal QT1 from low level to high level at time T c 1, which is a time Tsjla from the count start time TC[+, and changes the output terminal QT1 from low level to high level at the elapsed time point Tel
The output terminal QT2 is changed from low level to high level at time T c 2 when time T2 has elapsed since then, and the output terminal QT3 is changed from low level to high level at time Tc3 when time T3 has elapsed from this time Tc2.

Furthermore, when the signal applied to the reset terminal trap changes from high level to low level, this timer circuit 33 is reset by the fall of the signal. Reference numeral 34 denotes a relay coil for energizing/disconnecting the heater, and this is energized/disconnected by turning on/off an NPN type transistor 35, which is a switching element. Note that 36 is a diode for maintaining the transistor 35. 37 is a relay coil for energizing/disconnecting the fan drive motor; 38 is a light emitting diode for displaying the defrosting set;
These are NPN transistors 3 which are switching elements.
Power on/off is controlled by turning on/off 9. Furthermore, 40 is!
・This is a diode for protecting Rangemetal 39.

So, each temperature judgment circuit 15, 16.1? , flip-flop circuits 28, 29, 30 . Reset circuit 31
．． Timer circuit 33. The base of the transistor 35 and the base of the transistor 39 are connected to the AND circuit 41, 42° 43 and the OR circuit 44.
．． Inverter 45.46. Noah circuit 47.48.49
are connected as shown.

Now, the operation of the above configuration will be described. Now, in the state shown in FIG. 1, the output signal S31 of the reset circuit 31 is low level, and the timer circuit 33 is in the reset state (each output terminal QT
1. QT2 and QT3 are at low level), therefore,
The outputs of the OR circuits 47, 48, and 49 are at high level, and the reset terminal traps of the flip-flop circuits 28, 29, and 30 are at high level. Then, when the thawed object (at frozen temperature) is placed on the thawing plate 8 and the thawing set/reset switch 26 is turned on, the output signal 32S of the input circuit 25 changes to a high level. A high level output signal S2S is applied to the clock terminal CK of each flip-flop circuit 28, 29 and 30. As a result, each of the flip-flop circuits 28, 29 and 30 changes each set output terminal Q to a high level, and its output signals S28, 529 and S3° become a high level. Since the high level output signal 33G of the flip-flop circuit 30 is applied to the base of the transistor 39, it is turned on, and the relay coil 37, that is, the fan drive motor 12 is energized and driven, and the defrost set display signal is turned on. The light emitting diode 38 is energized and lit. or,
Since the high level output signal S30 from the flip-flop circuit 30 is also applied to the reset terminal trap of the timer circuit 33, the timer circuit 33 starts counting. On the other hand, when looking at the input and output of the AND circuits 41, 42 and 43, since the high level output signal S28 is given to one input terminal of the AND circuit 41 of the two-person type, its output is transmitted to the other input terminal. It changes according to the output signal SIS from the first temperature determination circuit 15, which is provided in 3.
Since the output signal S2B is applied to one input terminal of the human-powered AND circuit 42 as a low level signal inverted by the inverter 45, its output is applied to the signal applied to the other input terminal (in particular, the second temperature Judgment circuit 16
The output signal S2 is at a low level regardless of the output signal S, 6) from the inverter 46, and the output signal S2 is given to one input terminal of the three-manufactured AND circuit 43 as a low level signal inverted by the inverter 46. is set to a low level regardless of the signals applied to other input terminals (particularly the output signal s, 7 from the third temperature determination circuit 17). As a result, the output signal SIS of the first temperature determination circuit 15 is applied to the base of the transistor 35 via the AND circuit 41 and the OR circuit 4. With this,
The relay coil 34, that is, the heater 9 is the first temperature determination circuit 1.
The power is turned on and off by the output signal SIS of No.5.

In other words, the first 1R degree determination circuit 15 sets the upper limit la degree reference value E1. which is slightly higher than the upper limit temperature reference value and the lower limit temperature reference value of the other temperature determination circuits 16 and 17. h and lower limit lH degree J! ■Since the level of the output signal StS is changed based on the value E1sC, the upper limit temperature reference value E15
h and the lower limit temperature reference value E15 (). At the thawing start time TcO, as shown in FIG. 6, the temperature of the object to be thawed is quite low, so the detected temperature value Ek It is considerably lower than the -1-limit temperature reference value E1.h in the first temperature determination circuit 15, and therefore the heater 9 is energized and generates heat, and the object to be thawed is thereby heated via the thawing plate 8. In this case, since the fan 11 is being driven, cold air is also blown onto the object to be thawed by the fan 11. After this, the temperature detection value Ek based on the temperature sensor 10 of the temperature detection circuit 14 becomes "1". When the temperature rises to the limit temperature reference value El, h, the heater 9 is cut off.After this, the temperature of the thawing plate 8 begins to decrease due to heat exchange with the object to be thawed, and the detected temperature value Ek reaches the lower limit. When the temperature drops to the reference temperature E15f, the heater 9 is energized again.This process is repeated and the object to be thawed is thawed at time T1 of thawing start El+.

At this time T1, the upper limit temperature reference value E1. h and lower limit temperature reference value EIS' are slightly high, and '/l! of the object to be thawed itself! Since the i degree is low, there are many opportunities to energize the heater 9, in other words, the energization time is long while the power-off time is short. As a result, the amount of heating by the heater 9 becomes large, and the temperature of the object to be thawed is raised from its initial low temperature (frozen temperature) in a short period of time. In this case, although the amount of heating for the object to be thawed is large, since the initial temperature of the object to be thawed is low, deterioration of the back side of the object does not occur.

Next, when time T1 in the timer circuit 33 elapses,
At that time point T c 1, the output terminal QTI changes to high level. This timer circuit 33 maintains its output state (Qvt at high level, QT2 at low level, and QT3 at low level) from this point on until time T2. Then,
The flip-flop circuit 28 is reset by a high level signal from the output terminal QTI of the timer circuit 33, changing its set output terminal Q to a low level (the reset output terminal 0 is at a high level). As the output signal S2g of the flip-flop circuit 28 changes to low level, the output of the AND circuit 41 changes to the output signal 5.
15, and the AND circuit 42
Since the signal from the inverter 45 given to the input terminal becomes high level (the output signal S1B from the flip-flop circuit 29 given to the other input terminal is high level), the output of this AND circuit 42 is eventually sent to the second temperature determination circuit. 16 becomes the output signal S18. With this, transistor 35
In other words, the heater 9 is turned on and off in accordance with changes in the output signal S1B from the second temperature determination circuit 16.

The output signal S1B from the second temperature determination circuit 16 is the upper limit temperature reference value El in the second temperature determination circuit 16,
h and the lower limit temperature reference value Ets (changes based on the upper limit temperature reference value E, , h and the lower limit temperature reference value IEts)
Further, since the upper limit temperature reference value E1, h and the lower limit temperature reference value at the time TI are set to be lower than ts, the heater 9 can maintain the temperature as shown in FIG. The power is turned on and off in the temperature range where the detected value Ek is low.Therefore, there are many chances of the heater 9 being turned off, and the occurrence of a continuous current state is effectively prevented. As the amount becomes smaller, the bottom, which is the surface of the object to be thawed, does not become very hot, and the object is thawed while the internal temperature and the temperature of the back surface of the object become close to each other. In this case, since the temperature range between the upper limit temperature reference value E16h and the lower limit temperature reference value E1B'' is small, it becomes more effective in preventing the bottom of the object to be thawed from becoming H.

Then, at time Tc2 when time T2 in the timer circuit 33 has elapsed, at this time Tc2, output terminal QT2
changes to a high level, and the output state of the timer circuit 33 (QTl is at a high level, output terminal QTf is also at a high level, and output terminal QT3 is at a low level) is maintained at time T3. The flip-flop circuit 29 is activated by a high level signal from the output terminal QT2 of the timer circuit 33.
is reset and changes its set output terminal Q to low level. As the output signal 329 from the set output terminal Q of the flip-flop circuit 29 changes to low level, the output of the AND circuit 42 becomes the second ;! The inverter 4 is set to a low level regardless of the output signal 816 from the i-degree determination circuit 16, and is supplied to the AND circuit 43.
6 becomes high level (the output signal S30 from the flip-flop circuit 30 given to the other input terminal
(high level), the output of this AND circuit 43 becomes the output signal Sir from the third temperature determination circuit 17.

With this, the on/off of the transistor 35, that is, the energization/disconnection of the heater 9 is controlled by the output signal 5li from the third temperature determination circuit 17.
This is done in response to changes in t.

Temperature determination signal S17 from this second temperature determination circuit 17
” - Limit motion values El, h and lower limit temperature reference (iiE
17 Varies based on l. This -L limit temperature JA L
'fIrLE s 7 h and rJ lower limit temperature reference value El
r( is each upper limit at the above-mentioned time T1 and time T2;
Since the q value is set to be even lower than the n-degree base q value and the lower limit 1g base f'%l, the heater 9 is
As can be seen from FIG. 6, the current is turned off in a temperature range where the detected temperature value E Ic becomes a lower temperature. Therefore, the number of power outages to the heater 9 increases, and the amount of heat applied to the thawed object by the heater 9 becomes even smaller, and thawing is performed while more effectively preventing the bottom of the thawing object from heating up. Excessive thawing on the surface of the object can be effectively prevented, and therefore deterioration of the back surface of the object can be prevented. In this case, the temperature range between the upper limit temperature reference values El, h and the lower limit temperature reference value E17 (is even smaller, so it is more effective in preventing the bottom of the object to be thawed from becoming high temperature, and the deterioration of the back surface is further reduced. It can definitely be eliminated.

Thereafter, when the time T3 in the timer circuit 33 has elapsed, the output terminal QT of the timer circuit 33 at that time Tc3.
3 changes to high level. As a result, the flip-flop circuit 30 that was in the set state is reset,
That is, since the flip-flop circuits 28, 29 and 30 are all reset, the transistors 35 (
The heater is turned off and the power is cut off, the transistor 39 is also turned off, the fan motor 12 and the light emitting diode 38 for displaying the defrost set are cut off, and the timer circuit 33 is also reset because its reset terminal trap changes to low level. This completes the decompression.

As described above, according to this embodiment, the temperature determination circuits 15, 16, and 17, which have different limit temperature reference values for turning off the heater 9 and different lower limit 1M degree reference values for turning on the heater 9, are connected to the timer circuits. 33 etc., by selectively activating the heater drive control circuit 13 in order from the beginning of thawing, so that the upper limit temperature reference value and the lower limit 'tEA degree reference value are made high at the beginning of thawing, for example at time T1, and then Since the configuration is such that the temperature decreases in order at time T2 and time T3, at the beginning of thawing when the temperature of the object to be thawed is low and there is no risk of deterioration of the back side, the chances of power outage of the heater 9 can be reduced. The energization time of the heater 9 can be lengthened, and the amount of heat applied to the object to be thawed can be increased. Therefore, compared to the conventional method in which the upper limit temperature reference value and the lower limit temperature reference value are set lower from the start of thawing, this initial stage of thawing can be improved. In such a short period of time, the temperature of the object to be thawed can be raised to such a level that deterioration of the back side does not occur, and therefore the thawing time can be shortened. Furthermore, since the upper limit temperature reference value and the lower limit temperature reference value are successively lowered in two steps thereafter, thawing can proceed without continuous energization, or in other words, without generating soft surface parts.

In addition, in the above embodiment, the upper limit temperature reference value and the lower limit temperature reference value are set low in two steps, but this may be done by sequentially and continuously lowering them. Alternatively, it may be lowered in one step.

In addition, the present invention is not limited to the embodiments shown in the drawings marked -1-, and can be widely applied to defrosting devices in general, not just to defrosting devices for refrigerators. It can be modified and implemented.

[Effects of the Invention] As is clear from the above description, the present invention sets the heater drive control circuit to a -L limit temperature base value for turning off the heater and a lower limit of 11 degrees for turning on the heater. Since the temperature is set so that the value is high at the beginning of thawing and then becomes low, it is possible to quickly raise the temperature of the thawed material to a high temperature in the short period of time at the beginning of thawing. It is possible to eliminate the occurrence of an energized state, and therefore, it is possible to achieve an excellent effect that the time required for thawing can be greatly shortened while eliminating deterioration of the back surface of the thawed limb.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is an electric circuit diagram;
Figure 2 is a vertical side view of the main parts of the refrigerator, Figure 3 is a perspective view of the defrosting plate, and Figure 4 is a diagram for explaining the upper and lower temperature reference values of each temperature determination circuit. Figure, 5th
The figure shows the output operation of the timer circuit. In the figure, 3 is a thawing chamber, 8 is a thawing plate, 9 is a heater, 10 is a temperature sensor, 11 is a fan, 12 is a fan drive motor, 1
3 is a heater drive control circuit, 14 is a temperature detection circuit, 15.
16 and 17 are iRa determination circuits, 26 is a defrost set/reset switch, 28 degrees, 29 and 30 are flip-flop circuits, 33 is a timer circuit, 34 is a relay coil of Ichikawa for heater on/off, and 37 is for fan drive motor on/off. This is a relay coil.

Claims (1)

[Claims] 1. A heater that heats the object to be thawed stored in the thawing chamber, a temperature sensor that detects the temperature of the object to be thawed, and a heater that detects the temperature of the object when the temperature detected by this temperature sensor rises to the upper limit temperature reference value. and a heater drive control circuit that energizes the heater to drive and control the heater when the temperature drops to the lower limit temperature reference value when the temperature drops to the lower limit temperature reference value. A thawing device characterized in that the temperature reference value is high at the beginning of thawing and becomes low thereafter.