JPH0914816A - Defrosting device for evaporator in cold heat keeping device - Google Patents

Abstract

PURPOSE: To enable frosting adhered at an upper part of an evaporator to be efficiently melted by a method wherein an upper part and a lower part of the evaporator are provided with a defrosting lower part infrared ray heater and an electrical power supplied to the heater is set to have a specified rate. CONSTITUTION: An evaporator 2 is mounted in a space between an inner wall and an outer wall within a freezing chamber 1. A defrosting lower infrared ray heater 3 is arranged at a lower part of the evaporator 2 and a defrosting upper infrared heater 5 is arranged at an upper part of the evaporator 2. A capacity of each of both heaters 3, 5 is adjusted such that an electrical power supplying for both heaters may become a relation of (the defrosting lower infrared ray heater 3: the defrosting upper infrared ray heater 5)=8:2. Each of the heaters 3, 5 has a defrosting lower infrared ray heater protection cover 4 for protecting the heater against water droplets or shock and a defrosting upper infrared ray heater protection cover 6 for protecting the heater against water droplets or shock near it. A refrigerator circulation fan 7 for feeding cold air into the freezing chamber 1 is installed in a space communicated with a mounting space of the evaporator 2. In addition, a drain pan 8 for receiving water droplets is arranged at a lower part of the evaporator 2 and further there is provided a drain pipe 9 for use in discharging water droplets accumulated at the bottom surface of time drain pan out of the freezing chamber.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an evaporator defrosting device for a cooler for removing frost attached to an evaporator provided in a cooler such as a refrigerator, a refrigerator, a freezer and a freezer. Is.

[0002]

2. Description of the Related Art Generally, an evaporator used in a cold storage device such as a freezer-refrigerator cools its surface with water in the air or water released from a storage item to adhere to it as frost to grow. You can see the phenomenon. When frost grows on the surface of the evaporator, the performance of the evaporator deteriorates. Therefore, a defrosting device is conventionally provided to melt and remove the frost that has adhered and grown near the evaporator.

The structure will be described with reference to FIG. 8 which is a front view (a) and a side sectional view (b) showing the upper portion of a home refrigerator-freezer. FIG. 8 shows a defrosting device having a defrosting infrared heater 84, a defrosting infrared heater protection cover 83, a drain pan 85, and a drain pipe 87 below the evaporator 82 installed in the freezer compartment 81. ing.

During operation of the freezer-refrigerator, the air cooled by the evaporator 82 is partially stored in the freezer compartment 81 via the internal circulation fan 86, and partly stored in other storage though not shown. Sent to the room to cool each storage room, then duct 8
It returns to the evaporator 82 through 8 and is cooled again.

When this process is repeated, the water contained in the inflow air from the door and the water released from the food or the like are carried to the circulating air and become frost on the surface of the evaporator 82 to grow. In a general refrigerator / freezer, when the accumulated operating time is 10 hours or when the defrost switch is pressed, the fan 86 stops and the defrosting infrared heater 84 installed below the evaporator 82 is automatically energized to defrost. Is started.

The infrared heater 84 for defrosting has an outer periphery covered and protected by a glass tube. Further, the glass tube is provided with a metal on the upper portion of the infrared heater for defrosting so that water drops do not come into contact with the glass tube when the temperature rises due to energization of the heater. Protective cover 8
3 are provided. When the infrared heater 84 for defrosting is electrically heated, the air around the evaporator 82 is heated and rises by natural convection to melt the frost that has adhered and grown on the surface of the evaporator 82. The melted water drops flow into the drain pan 85 and are discharged to the outside of the freezer-refrigerator through the drain pipe 87.

Further, Japanese Unexamined Patent Publication No. 63-129287 discloses a defrosting device in which two or more defrosting heaters are used. The main structure is as shown in FIG.
FIG. 9 shows the evaporator chamber of the showcase. The defrosting heaters 92 and 93 are provided at the left and right ends of the evaporators 91 and 95, respectively.
96 and 97 are installed so that the frost adhering to one evaporator can be removed by energizing the defrosting heaters installed at both ends of the evaporator while the other evaporator cools the showcase. I have it.

When defrosting the frost that has adhered and grown on the evaporator 91, the defrosting heaters 92 and 93 are energized to perform defrosting. During this time, the indoor air flow is sent from the right side to the left side when viewed from the back of the showcase by the air circulation fan 94 (solid arrow in the figure). The defrosted air of the evaporator 91 is cooled by the evaporator 95 and sent to the room. When defrosting the frost that has adhered and grown on the evaporator 95, the indoor air circulation direction is reversed by rotating the air circulation fan 94 in the reverse direction (the broken line arrow in the figure), and the defrost heaters 96 and 97 are used. And then defrosted. Further, according to the publication, the air from which one of the evaporators has been defrosted has already been deprived of heat due to the latent heat of fusion of the frost, so that the temperature does not rise much even when it reaches the other evaporator for cooling. Has been done.

[0009]

However, as described above, a mechanism for defrosting the evaporator for a cooler by using only natural convection of air by using the defrosting infrared heater 84 installed at the bottom of the evaporator 82. Since the defrosting of the frost adhering to the surface of the evaporator 82 is performed in the process in which the heated air rises in a circular arc from the lower part of the evaporator 82, the air wraps around even when the defrosting is near the end. The frost on the top of the difficult evaporator 82 remains unmelted. That is, the energy input to the infrared heater 84 for defrosting installed in the lower part of the evaporator 82 is not used effectively and the intended purpose cannot be achieved. In addition, with respect to such a problem, if excessive heating is performed to prevent residual frost, the overheated air flows into the low-temperature refrigerator / freezer, which causes a temperature rise of the air inside the refrigerator during defrosting, resulting in energy loss. growing.

Further, in the above-mentioned Japanese Patent Laid-Open No. 63-129287, when defrosting the frost adhered and grown on the evaporators 91 and 95, the other evaporator cools the room while the other one of the evaporators is cooled. In order to perform defrosting, the indoor circulation fan 94 is operated by switching the rotation direction as described above. With such a defrosting mechanism, the cold air in the room directly hits the defrosting heater 92, the temperature rise of air is low relative to the input energy of the defrosting heater 92, and the input energy is effectively used for defrosting. The defrosting efficiency is reduced.

Further, since the heat of the defrosting heater 93 is taken in by the indoor circulation fan 94, the defrosting heater 93 is used.
Most of the heat generated in the defrosting heater 93 flows to the evaporator 95 side, and the defrosting efficiency of the defrosting heater 93 is significantly reduced as in the case of the defrosting heater 92. Since it reaches the evaporator 95 as it is, it is inevitable that a considerable heat load is applied to the evaporator 95.

Further, even if the indoor circulation fan 94 is stopped,
If the defrosting heaters 92 and 93 are installed on the left and right sides of the evaporator 91, the frost in the central portion of the evaporator 91 remains unmelted, and it takes a considerable amount of time and energy to completely remove the frost. The frost efficiency must be very low.

In view of such drawbacks, the present invention makes it possible to efficiently melt the frost on the upper portion of the evaporator, which is difficult to be melted by the conventional defroster. Further, by devising the operation of the defrosting infrared heater, the defrosting efficiency can be improved, the power consumption of the defrosting infrared heater can be reduced, and the energy saving system can be achieved. An object of the present invention is to provide a defrosting device for an evaporator for a cold storage device, which is capable of efficiently performing defrosting in a short time to reduce power consumption of an infrared heater for defrosting and suppress an increase in air temperature in the cold storage device to save energy. To do.

[0014]

In order to solve the above-mentioned problems, the present invention focuses on the upper part of the evaporator where frost was difficult to be melted to the end in the conventional defrosting device, and the lower part of the evaporator is similar to the conventional device. A lower infrared heater for defrosting is installed in the above, and an upper infrared heater 5 for defrosting is installed above the evaporator 2 to form a defrosting device of a cooler. Furthermore, the ratio of the power supplied to the defrosting lower infrared heater and the defrosting upper infrared heater is appropriately set (preferably defrosting upper infrared heater power supply: defrosting lower infrared heater power supply =
2: 8), defrost the evaporator.

The defrosting apparatus of the present invention is provided with a timer for controlling the operation timing of the defrosting lower infrared heater and the defrosting upper infrared heater, and a defrosting upper and lower infrared heater changeover switch 32. At the start of frost, the lower infrared heater for defrosting is operated, then switched to the upper infrared heater for defrosting, and finally the lower infrared heater for defrosting is operated to perform defrosting.

Further, the defrosting apparatus of the present invention is provided with an upper temperature sensor for controlling the input switching of the defrosting lower infrared heater and the defrosting upper infrared heater, a lower temperature sensor, and a defrosting upper and lower infrared heater changeover switch. By configuring and using the detection information of each of the above temperature sensors to control switching from the defrosting infrared heater to the defrosting infrared heater or switching from the defrosting infrared heater to the defrosting infrared heater 3. Perform defrosting.

[0017]

As described above, by installing the upper defrosting infrared heater also on the upper part of the evaporator to constitute the defrosting device, the defrosting infrared heater conventionally installed on the lower part of the evaporator is used for heating. Besides, it is possible to defrost the frost on the upper portion of the evaporator, which is difficult to be melted in the related art, in a short time by locally heating with the infrared heater for upper defrosting.

When the defrosting infrared heaters installed above and below the evaporator are connected in parallel, and the heaters have different capacities, the power supply ratio of the defrosting upper and lower infrared heaters is changed. By performing the defrosting, the defrosting can be performed without leaving the frost, and particularly, the defrosting can be efficiently performed in a short time with the power consumption amount equivalent to that of the conventional system.

Further, the defrosting infrared heaters installed above and below the evaporator are deenergized at the start of defrosting by energizing the lower defrosting infrared heater at the start of defrosting and then switching to the upper defrosting infrared heater. The heat generated from the frost infrared heater first heats the entire bottom of the evaporator to melt the adhered frost, then the defrosting upper infrared heater mainly melts the frost above the evaporator. To do.

The melted drain water is dropped into the middle and lower areas of the evaporator, but the middle area of the evaporator is slightly heated by the lower infrared heater for defrosting at the start of defrosting, so that it does not refreeze. It has the effect of slightly raising the temperature of frost in the central region. After that, the lower infrared heater for defrosting is switched again to continue defrosting, thereby efficiently defrosting the frost in the central region.

Further, the defrosting can be optimized by sensing the switching timing of the infrared heaters for upper and lower defrosting by a temperature sensor installed in the vicinity of the evaporator and controlling the switching. The infrared heater for frost is effectively used to defrost efficiently in a short time.

[0022]

【Example】

<Example 1> Hereinafter, examples of the present invention will be described from Example 1. FIG. 1 is a configuration diagram showing an embodiment in which the present invention is applied to a freezer compartment of a home refrigerator / freezer. In FIG.
(A) is a front view, (b) is a side sectional view. An evaporator 2 is installed in the space between the inner wall and the outer wall of the freezing compartment 1 as in the conventional device. A lower defrosting infrared heater 3 is provided on the lower side of the evaporator 2, and an upper defrosting infrared heater 5 is provided on the upper side thereof. Heater 3: The upper infrared heater 5 for defrosting is adjusted in capacity so as to be 8: 2.

A defrosting lower infrared heater protection cover 4 and an upper defrosting infrared heater protection cover 6 for protecting the heaters from water drops and impacts are attached to the heaters 3 and 5, respectively. . An internal circulation fan 7 for sending cold air into the freezer compartment 1 is installed in a space continuous with the installation space of the evaporator 2, and a drain pan 8 for receiving water droplets is installed below the evaporator 2. ing. On the bottom surface of the drain pan 8, a drain pipe 9 for discharging the accumulated water droplets to the outside of the freezer compartment is provided through the freezer partition wall. The space between the freezer compartment wall and the partition wall is provided as a duct 10 and serves as a cold air circulation path.

FIG. 2 is a block diagram showing an electric control system around the defrosting infrared heaters 3 and 5 of the refrigerator having the above-mentioned structure. The defrosting infrared heaters 3 and 5 adjusted to have different capacities as described above are connected in parallel and connected to the power supply 22. To control the energization of each infrared heater,
A control circuit A is provided between the power source 22 and the infrared heaters 3, 5. The control circuit A includes an on / off switch 23, and is programmed so as to be automatically switched from the operation mode to the defrost mode in advance at the time when the integrated cooling operation time of the refrigerator / freezer reaches 10 hours. On / off control is performed by manual operation from the defrost switch 21 at the time.

Next, the optimization of the electric power supplied to both heaters in the defrosting apparatus of this embodiment in which the infrared heaters 3 and 5 for defrosting are installed on the upper and lower sides of the evaporator will be described. First, an infrared heater for defrosting used in a home refrigerator / freezer is usually about 170 W, and in an apparatus in which the heater 84 is installed only under the evaporator 82 as shown in FIG. Defrosting took about 30 minutes. By energizing the infrared heater 84, the frost in the lower region of the evaporator 82 is sequentially melted, but even when the defrosting is almost completed, the frost attached to the upper part of the evaporator may not be melted and may remain. .

As in the present embodiment shown in FIG. 1, heaters 3 and 5 are installed on both upper and lower sides of the evaporator 2, and the upper and lower heaters are both 17
By simultaneously supplying 0 W, not only the evaporator lower part but also the frost attached to the upper part could be removed in a defrosting time of about 6 minutes. However, in this case, since the upper and lower infrared heaters 3 and 5 were each energized with 170 W, the defrosting efficiency is low, which is not preferable.

Therefore, the total input to the two upper and lower defrosting infrared heaters 3 and 5 is set to one input, that is, 170 W, to improve the defrosting efficiency. The experimental results in this case are shown in FIG. In the figure, the horizontal axis represents the input ratio of the upper and lower heaters. The numerator represents the input power of the upper infrared heater 5, and the denominator represents the input power of the lower infrared heater 3.

The vertical axis represents the defrosting efficiency. The defrosting efficiency here is the melting latent heat corresponding to the amount of drain collected by the experiment divided by the heater power consumption, and only the latent heat change of water is considered. However, changes in sensible heat are not considered. FIG.
As can be seen, by performing the defrosting with the power supplied to the upper infrared heater 5 for defrosting being 20% or less, the efficiency is improved as compared with the conventional case where the lower infrared heater is used alone.

Next, the operation of the present embodiment in which the capacity is adjusted so that the defrosting lower infrared heater 3: the defrosting upper infrared heater 5 = 8: 2 will be described. In the cooling operation mode of the freezer-refrigerator, a part of the air cooled by the evaporator 2 is sent into the freezing compartment 1 through the internal air circulation fan 7 to cool the freezing compartment 1 and then evaporate through the duct 10. It returns to the vessel 2 and is cooled again. When the above cooling process is repeated, frost adheres to the surface of the evaporator 2 and grows due to the water contained in the inflowing air from the door, the water released from the food, and the like.

In a general household refrigerator-freezer, the switching from the cooling operation mode to the defrosting mode is preprogrammed in the on / off switch 23 of the control circuit A, and when the accumulated operation time has passed 10 hours or a service person. This is the case when the defrost switch 21 is manually pressed by. In either case, the defrost mode signal turns on.
The / off switch 23 is turned on.

Then, the internal circulation fan 7 is stopped and the defrosting lower infrared heater 3 installed in the lower portion of the evaporator 2 and the upper defrosting infrared heater 5 installed in the upper portion of the evaporator 2.
Power is supplied to the defrosting lower infrared heater 3
At W, the upper infrared heater 5 for defrosting operates at 34 W to start defrosting. That is, the input of the upper infrared heater 5 for defrosting:
The defrosting lower infrared heater 3 operates at an input ratio of 2: 8.

Defrosting lower infrared heater 3 connected in parallel
When the upper infrared heater 5 for defrosting is energized, the evaporator 2
The surrounding air is heated by the defrosting lower infrared heater 3 and rises by natural convection, and the frost that has adhered and grown on the surface of the evaporator 2 is sequentially melted from the frost in the lower region of the evaporator 2. At the same time, the defrosting upper infrared heater 5 melts the frost in the upper region of the evaporator 2.

As the melting progresses, the frost-melting water in the upper area of the evaporator 2 melted by the heat of the defrosting upper infrared heater 5 adheres to the middle and lower areas of the evaporator 2 and is not yet melted. Dropping on frost, the temperature of the frost is raised by the heat of the melted water, and the defrosting effect is produced in addition to the direct heat from the upper and lower defrosting infrared heaters.

As a result, the frost on the upper portion of the evaporator 2 which had been feared to remain unmelted until the end was melted by the defrosting upper infrared heater 5 at the initial stage of defrosting, and the lower infrared ray for defrosting was used. The burden on the heater 3 is lightened, and the defrosting effect of the dropped molten water is added. The melted water from the infrared heaters 3 and 5 for defrosting flows down into the drain pan 8 and is collected, and is discharged to the outside of the freezer-refrigerator via the drain pipe 9.

Second Embodiment Another embodiment according to the present invention will be described. The configuration of the defroster is the same as that of the first embodiment except for the configuration of the electric circuit, so the configuration of the electric circuit will be described. FIG. 3 is a block diagram showing an electric circuit around the infrared heater for defrosting according to this embodiment. The two defrosting infrared heaters 3 and 5 of the present embodiment are designed to have the same capacity, and energization is switched by the changeover switch 32 incorporated in the control circuit B.

The control circuit B is a defrost switch 2 for ON / OFF control by manual operation as in the first embodiment.
1, and an on / off switch 23 pre-programmed to switch between the operation mode and the defrosting mode is provided, and in the present embodiment, the defrosting lower infrared heater 3 and the defrosting upper infrared heater 5 are switched. A changeover switch 32 for energizing is provided, and a timer 31 for setting the control timing of the changeover switch 32.
Is provided.

The lower infrared heater 3 for defrosting and the upper infrared heater 5 for defrosting of this embodiment are switched to 17 each.
The power of 0 W is supplied, and the frost adhering to the evaporator 2 is efficiently removed by the operation of the two heaters of the lower and upper infrared heaters 3 and 5 for defrosting.

Next, the optimization of the electric power supplied to the heaters when the defrosting infrared heaters 3 and 5 on the upper and lower sides are switched and operated by the changeover switch 32 will be described. First, an experiment conducted for setting the optimum operation timing of the defrosting upper infrared heater 5 will be described.

Immediately after the start of defrosting, the upper infrared heater 5 for defrosting
When 10 minutes later, the lower infrared heater 3 for defrosting is switched to and defrosting is performed to the end, the defrosting efficiency becomes 28.9%, which is worse than the efficiency shown by the conventional device. Immediately after the start of defrosting, drain water generated by melting due to the heat of the defrosting upper infrared heater 5 drops into the middle area of the evaporator 2, where the drain water is re-frozen and adheres and grows on the evaporator 2. This is because the frost generation is strengthened.

Next, for 10 minutes from the start of defrosting, defrosting is first performed by the lower infrared heater 3 for defrosting, and then heating is performed by the upper infrared heater 5 for defrosting for 10 minutes, and the lower infrared heater for defrosting is completed until defrosting is completed. 3 was energized again for defrosting. In this case, the defrosting efficiency is 28.2%, which is lower than that of the conventional device. It is considered that the reason is that when the other heater is switched in a state where the heating performed at the start of defrosting is not sufficient, refreezing occurs similarly to the above pattern before the melting proceeds. Therefore, as a result of setting the energization time of the defrosting start heater long for 5 minutes, it was confirmed that the defrosting efficiency was 36.4%, which was about 10% higher than the conventional device.

The operation of this embodiment based on the above experimental results will be described below. However, the processes other than the defrosting are the same as those described in the first embodiment, and the description thereof will be omitted.
In a general household refrigerator-freezer, when the defrosting mode is entered due to the operation of the defrosting switch 21 or the accumulated operating time of 10 hours, the timer 31 is turned on after the on / off switch 23 to turn on the inside circulation. The fan 7 stops. Then, first, the defrosting lower infrared heater 3 installed in the lower portion of the evaporator 2 is energized, and the energization for 15 minutes set in the timer 31 is performed to start defrosting.

After 15 minutes, the first time elapsed signal is output from the timer 31 to the defrosting upper / lower infrared heater changeover switch 32, the power supply is switched to the defrosting upper infrared heater 5 side, and the vicinity of the upper portion of the evaporator 2 is changed. Heating the timer 31
Defrost for 10 minutes. Timer 31 is 2 from the start of defrosting
After 5 minutes, the second time elapse signal is output to the defrosting upper and lower infrared heater changeover switch 32, and the lower defrosting infrared heater 3 side is energized to continue defrosting.

The timing for switching the energization of the upper and lower heaters is one example, and depends on the shape of the evaporator, the positional relationship with the heater, and the like, and if the specifications of the evaporator change, naturally there is an optimum value corresponding thereto. To do. Therefore, the switching timing of the infrared heater for defrosting of the present embodiment is configured by programming the timer 31 of the control circuit B by checking the optimum condition in advance according to the configuration of the device.

<Embodiment 3> Another embodiment of the present invention will be described. The configuration excluding the electric circuit is the same as that of the first embodiment, and the description is omitted. FIG. 4 is a block diagram showing an electric circuit around the infrared heater for defrosting of this embodiment. A control circuit C is provided between the infrared heaters 3 and 5 and a power supply circuit 22 for controlling energization. ing.

In this embodiment, infrared heaters 3 and 5 are used.
Is performed by detecting the temperature of the elbow pipe, and the control circuit C includes a lower temperature sensor 41 and an upper temperature sensor 42 for controlling the changeover switch 32.
The detection output of each temperature sensor 41, 42 is input to the changeover switch 32 and becomes a signal for controlling the energization of the heater.

FIG. 5 shows the evaporator 2 and the lower temperature sensor 4 described above.
1, the positional relationship of the upper temperature sensor 42 is shown. In this embodiment, the upper and lower infrared heaters for defrosting are each 170 W.
In order to efficiently defrost the frost on the upper portion of the evaporator 2 by the upper infrared heater 5 for defrosting, the upper and lower defrosting is performed at an optimum timing regardless of the amount of frost attached and grown on the evaporator 2. Switch the infrared heater.

Next, the installation locations of the temperature sensors 41 and 42 will be described. When controlling the switching of the upper and lower infrared heaters for defrosting, the most sensitive places around the evaporator for the cooler are the pipes and fins of the evaporator. Therefore, in the present embodiment, the evaporator 2 which is easy to sense even when the evaporator installation room is small, such as a general household refrigerator / freezer.
I focused on the temperature of the elbow pipe.

The lowermost elbow pipe 51 of the evaporator 2 which is the most sensitive among them is sensed by the lower temperature sensor 41, and the temperature of the uppermost elbow pipe 52 is sensed by the upper temperature sensor 42.
The energization switching of the infrared heater for defrosting is controlled by the temperature detection signals 1 and 42. As the upper and lower temperature sensors 41 and 42, sensors such as thermistors are used.

Here, the elbow pipes 51 and 5 respectively.
FIG. 7 shows the defrosting efficiency when the temperature of 2 is changed from + 1 ° C. to + 3 ° C. as compared with the defrosting start temperature.
In FIG. 7, the horizontal axis shows the temperature rise on the upper elbow pipe 52 side, and the temperature rise on the lower elbow pipe 51 side is shown in the figure. From this figure, the temperature rise in the case where the defrosting efficiency is improved as compared with the conventional device is the case where the elbow pipe 52 temperature is + 1 ° C and the elbow pipe 51 temperature is + 3 ° C (about 33%).
Elbow pipe 52 Temperature is + 2 ℃, Elbow pipe 51
This is the case where the temperature is + 1 ° C. (35.7%), and the latter case has the highest defrosting efficiency.

The operation of this embodiment will be described below.
However, the processes other than the defrosting are the same as those described in the first embodiment, and the description thereof will be omitted. When entering the defrosting mode in a general household refrigerator-freezer, the internal circulation fan 7 is stopped, the on / off switch 23 of the control circuit C is turned on, and the defrosting upper / lower infrared ray changeover switch 32 is used for defrosting. On the side of the lower infrared heater 3, first, the lower infrared heater 3 for defrost installed in the lower portion of the evaporator 2 is energized to start defrosting.

Then, when the temperature of the elbow pipe 51 is sensed by the lower temperature sensor 41 and reaches + 1 ° C., a temperature detection signal is output to the defrosting upper / lower infrared heater changeover switch 32, and the heater to be energized is defrosted. Switch to the upper infrared heater 5 side to continue defrosting. After that, the temperature of the upper elbow pipe 52 is sensed by the upper temperature sensor 42, and when it is detected that the temperature rise reaches + 2 ° C., the temperature detection signal is output again to the defrosting upper and lower infrared heater changeover switch 32 to perform defrosting. The infrared heater 3 is switched to the side, and electricity is supplied until defrosting is completed.

The heater switching timing of the control circuit C in this embodiment is a condition peculiar to the evaporator, and if the evaporator specification changes, naturally there is an optimum value corresponding thereto. Therefore, the infrared heater is switched by preliminarily checking the relationship between the defrosting efficiency and the switching timing based on the detection output of the temperature sensor, and pre-programming the control circuit C with a process in which the switching is executed with the optimum temperature sensor output.

[0053]

According to the present invention as described above, claim 1
In the above, since the heating element is also installed on the upper side of the evaporator to positively heat the upper surface of the evaporator, the adhered frost can be efficiently removed during the defrosting mode, and the efficiency of the evaporator is improved. be able to.

In the second aspect, since the capacity of the lower heating element is set to be larger than that of the upper heating element and installed above and below the evaporator, it is possible to effectively use electric power to remove frost on the upper portion of the evaporator which is difficult to melt. It can be melted and the efficiency of the evaporator can be increased without increasing the power consumption.

In the third aspect, by setting the electric power supplied to the upper and lower heating elements in the defrosting mode to the optimum value,
Further efficiency such as power consumption and defrosting required time can be achieved.

In the fourth aspect, since the energization of the heating elements installed above and below the evaporator is controlled by the timer, it is possible to control with a simple mechanism, and it is possible to easily obtain a highly efficient defrosting device. You can

In the fifth aspect, the upper and lower heating elements are energized to start defrosting by energizing the lower heating element to start melting the frost adhering in advance, and then the upper heating element is energized to defrost the upper side of the evaporator. Is pre-programmed to positively melt and then energize the lower heating element again to complete defrosting, so that efficient defrosting with low power consumption can be reliably performed.

In the sixth aspect, since the temperature of the evaporator is detected and the energization of the heating element is controlled, the defrosting can be controlled at the optimum timing, the heating of the heating element is prevented, and the cooling device is recooled. It is not necessary to spend unnecessary energy for time, and it is possible to obtain a defrosting device that not only saves energy but also shortens the defrosting time.

In the seventh aspect, the reliability of the defrost control can be enhanced by selecting the installation of the temperature sensor that forms the signal for controlling the energization of the heating element.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an embodiment of a defrosting device for an evaporator according to the present invention.

FIG. 2 is a block diagram showing an electric circuit around a defrosting heater of an embodiment of the defrosting device according to the present invention.

FIG. 3 is a block diagram showing an electric circuit around a defrosting heater of another embodiment of the defrosting device according to the present invention.

FIG. 4 is a block diagram showing an electric circuit around a defrost heater of still another embodiment of the defrost apparatus according to the present invention.

FIG. 5 is a configuration diagram of an evaporator of the embodiment shown in FIG. 4 ((a) front view, (b) side sectional view).

6 is a defrosting efficiency characteristic diagram with respect to the power supply ratio of the infrared heater for vertical defrosting of the embodiment shown in FIG.

FIG. 7 is a defrosting characteristic diagram for a temperature sensor detection output in the elbow pipe of the embodiment shown in FIG.

FIG. 8 is a configuration diagram showing a conventional defrosting device.

FIG. 9 is a configuration diagram showing a conventional defrosting device.

[Explanation of symbols]

 1 Freezer 2 Evaporator 3 Lower infrared heater for defrost 4 Lower infrared heater protection cover for defrost 5 Upper infrared heater for defrost 6 Upper infrared heater protection cover for defrost 7 Circulation fan 8 Drain pan 9 Drain pipe 10 Duct 21 Defrost switch 22 Power supply 23 on / off switch 31 Timer 32 Upper and lower infrared heater changeover switch for defrost 41 Lower temperature sensor 42 Upper temperature sensor 51 Elbow pipe 52 Elbow pipe

Claims (7)

[Claims] 1. A defrosting device for an evaporator for a cooler, wherein heating elements are arranged on both upper and lower surfaces of the evaporator, and a power supply circuit for the heating element is provided with a control circuit for controlling energization. . 2. The defroster for an evaporator for a cooler according to claim 1, wherein the heating element is designed such that the lower heating element has a larger capacity than the upper heating element. 3. The evaporation for a cold-storage device according to claim 2, wherein the control circuit sets the electric power supplied to each heating element to upper heating element: lower heating element = 2: 8. Defroster. 4. The control circuit has a built-in timer for pre-programming the energization time to the heating element, and after energizing the lower heating element for a predetermined time at the start of defrosting, controls the switching of energization to the upper heating element. The defrosting device for an evaporator for a cooler according to claim 1, wherein 5. The control of energization of the heating element programmed in the timer of the control circuit is such that the lower heating element is energized at the start of defrosting and then switched to energize the upper heating element to deposit frost on the upper side of the evaporator. 5. The defrosting apparatus for the evaporator for a cooler according to claim 4, wherein the switching timing for melting and melting again and energizing the lower heating element to complete defrosting is programmed. 6. The control circuit includes a temperature sensor installed in the vicinity of the evaporator, and a detection output of the temperature sensor is input to a changeover switch of the control circuit to energize a lower heating element at the start of defrosting. The defrosting device for an evaporator for a cooler according to claim 1, wherein energization of the lower heating element is switched and controlled by a preset temperature sensor output. 7. The temperature sensors are installed near the lowermost elbow pipe and the uppermost elbow pipe of the evaporator, respectively, and the detection output of each temperature sensor is input to a changeover switch of the control circuit to supply heat to a heating element. The defrosting device for an evaporator for a cooler according to claim 6, wherein energization switching control is performed.