JPH0755327A - Defrosting device for cooling device - Google Patents

Abstract

PURPOSE:To provide a defrosting device for a cooling device which is capable of setting an optimum drip time automatically in conformity with the amount of frost deposited on the surface of a vaporizer. CONSTITUTION:A microcomputer 27 stops the heating of a vaporizer based on the output of a defrost return sensor 29 when the temperature of the vaporizer reaches a specified defrost end temperature after having started to defrost the vaporizer and then restarts cooling operation after drip time. The microcomputer 27 further computes the drip time based on an estimated value by a defrost time T2 which estimates the defrost time of the vaporizer and restarts the cooling operation after the lapse of the drip time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a defrosting device for a low-temperature showcase equipped with an evaporator and a cooling device such as a refrigerator / freezer.

[0002]

2. Description of the Related Art Heretofore, a cooling device of this type has been disclosed in Japanese Patent Publication No.
As disclosed in JP-A-70546 (F25D21 / 08) as a low temperature showcase, cool air that has exchanged heat with the evaporator is circulated in the chamber by a blower for cooling, and the evaporator is heated by an electric heater for evaporation. We are defrosting the vessel. At this time, since ice blocks also drop from the evaporator along with the water droplets onto the dew tray, the time it takes for them to completely fall,
It is necessary to secure the time until the ice blocks on the dew pan are melted and discharged.

Therefore, in the above publication, after defrosting by heating the electric heater is completed, a predetermined draining time is set and the cooling operation is restarted after the draining time elapses so that dew and ice blocks from the evaporator are removed. It had time to fall and the ice block on the dew pan was melted and discharged.

[0004]

However, in the conventional low temperature showcase, since the draining time is a fixed time such as 5 minutes, the amount of frost on the evaporator changes due to the change of the season, and the fall occurs. If the amount of defrost water or ice blocks increases, the time is insufficient and frost residue or refreezing occurs. Conversely, if the amount of defrost water or ice blocks decreases, the drainage time becomes excessive. There was a problem that caused unnecessary temperature rise in the refrigerator.

Further, even if the draining time can be changed depending on the season in order to solve this, the user has to change the setting one by one, so that the management becomes complicated and the setting is actually changed. There was also a problem that was not done. The present invention has been made to solve the conventional technical problem, and provides a defrosting device for a cooling device that can automatically set an optimum draining time according to the amount of frost formed on an evaporator. The purpose is to do.

[0006]

A defrosting device of the present invention comprises a defrosting means for heating an evaporator of a cooling device, a temperature detecting means for detecting the temperature of the evaporator, and a control means for controlling the defrosting means. After the cooling operation is stopped and the defrosting of the evaporator is started by the defrosting means, it is removed when the temperature of the evaporator reaches a predetermined defrosting end temperature based on the output of the temperature detecting means. While stopping the heating action of the frost means, is applied to a cooling device that restarts the cooling operation after placing a draining time, provided with a time limit means for integrating the defrost time by the defrost means, the control means, The water draining time is calculated based on the integrated value of the time limiting means, and the cooling operation is restarted after the water draining time has elapsed.

[0007]

According to the defrosting device of the cooling device of the present invention, the defrosting time of the evaporator is integrated by the time limiting means, and the subsequent draining time is calculated based on this integrated value. When the amount of frost on the evaporator increases and the defrosting time becomes longer, the draining time also becomes longer, and conversely, the amount of frost on the evaporator decreases and the defrosting time becomes shorter in winter, etc. When it becomes difficult, by shortening the drainage time as well, it becomes possible to set the optimum drainage time according to the amount of frost formation. As a result, it is possible to eliminate the occurrence of unnecessary temperature rise due to residual frost and excessive drainage time.

[0008]

Embodiments of the present invention will be described below in detail with reference to the drawings. 1 is a block diagram of an electric circuit of a low temperature showcase A as an embodiment of a cooling device to which the defrosting device of the present invention is applied, FIG. 2 is a perspective view of the low temperature showcase A, and FIG. It is a refrigerant circuit diagram. In FIG. 2, the low temperature showcase A of the embodiment has a heat-insulating box body 21 that opens to the front to form an interior (not shown), and a glass door 22 that opens and closes the front opening of the heat-insulating box body 21.
23.

Next, in FIG. 3, 1 is a compressor, SV 1 is a three-way solenoid valve, 2 is a condenser equipped with a blower CF, 3 is a liquid receiver, 4 is an expansion valve, 5 is an evaporator equipped with a blower EF. , 6 are gas-liquid separators, which are annularly connected by a high-pressure gas pipe 7, a high-pressure liquid pipe 8, a low-pressure liquid pipe 9 and a low-pressure gas pipe 10.
A cooling cycle as shown by the solid line is formed. Further, a bypass pipe 12 having a check valve 11 is connected between the three-way solenoid valve SV1 and the low pressure liquid pipe 9 to form a defrost cycle as indicated by a dashed arrow.

Reference numeral 13 denotes a dew tray provided under the evaporator 5, which is provided with a dew tray heater 14 as a heating means.
The evaporator 5 is installed in the refrigerator of the low temperature showcase A, and the blower EF forcibly circulates the cool air that has exchanged heat with the evaporator 5 in the refrigerator. Further, the dew tray 12 has a function of receiving defrosting water and ice blocks that are dropped when the evaporator 5 is defrosted, and guiding the defrosting water and ice blocks to a drain pipe (not shown) to discharge them.

Next, referring to FIG. 1, the microcomputer 27 serving as a control means inputs the output of the inside temperature sensor 28 for detecting the inside temperature of the heat insulating box 21 and the temperature of the evaporator 5 to the inside. The output of the defrosting recovery sensor 29 as the temperature detecting means is input. On the other hand, the output of the microcomputer 27 includes the compressor 1, the blowers CF and EF, the three-way solenoid valve SV1, and the dew pan heater 14.
Are connected.

Next, the operation of the low temperature showcase 1 having the above configuration will be described. Based on the output of the internal temperature sensor 28, the microcomputer 27 operates the compressor 1 and turns off the three-way solenoid valve SV1 when the internal temperature of the low temperature showcase 1 reaches an upper limit value such as + 5 ° C. 3 forms a cooling cycle as indicated by the solid line arrow in FIG. 3 to execute the cooling operation. As a result, the high-temperature gas refrigerant discharged from the compressor 1 is air-cooled and condensed in the condenser 2 via the high-pressure gas pipe 7, narrowed down by the expansion valve 4 via the high-pressure liquid pipe 8, and then the low-pressure liquid pipe 9 And flows into the evaporator 5. The refrigerant that has flowed into the evaporator 5 evaporates there and removes heat from the surroundings to exert a cooling effect. The air cooled by the cooling action is circulated in the refrigerator by the blower EF as described above. The refrigerant exiting the evaporator 5 returns to the compressor 1 via the low pressure gas pipe 10.

By such a cooling operation, the temperature in the refrigerator is, for example, +
When reaching the lower limit of 3 ℃, microcomputer 27
Stops the compressor 1 based on the output of the internal temperature sensor 28. The microcomputer 27 continuously operates the blowers CF and EF. By such a cooling operation, the inside of the low temperature showcase A is cooled to an average of + 4 ° C.

Next, the defrosting control of the evaporator 5 by the microcomputer 27 will be described with reference to FIG. FIG. 4 shows a flow chart of a program relating to defrost control of the microcomputer 27. The microcomputer 27 resets or clears everything at the same time when the power is turned on, and counts the cooling operation time by the defrost timer T1 which has its function. Then, when a predetermined defrosting interval such as 12 hours elapses, the microcomputer 27 causes the defrosting timer T1.
Is cleared and the defrosting operation is started in step S1.

In this defrosting operation, the microcomputer 27 energizes the dew pan heater 14 and continues to operate the compressor 1 to energize the three-way solenoid valve SV1 to blower C.
Stop F and EF. When the three-way solenoid valve SV1 is energized, the flow direction of the high temperature gas refrigerant is switched from the high pressure gas pipe 7 to the bypass pipe 12 as indicated by the broken line arrow in FIG.
Is heated by the inflow of the high temperature gas refrigerant and defrosted.

Next, the microcomputer 27 integrates the defrosting time (the time during which the high temperature refrigerant is supplied to the evaporator 5) by the defrosting time timer T2 which has its function in step S2, and then proceeds to step S3. Based on the output of the defrost recovery sensor 29, the temperature of the evaporator 5 is, for example, + 10 ° C.
It is determined whether or not a predetermined defrosting end temperature such as the above has been reached, that is, whether or not the defrosting return condition is satisfied. If not, the process returns to step S1 to continue the defrosting operation. Defrosting water and ice blocks that have fallen from the evaporator 5 due to such defrosting operation are received by the dew tray 13,
It is discharged by a drain pipe (not shown). Further, at this time, the ice blocks falling on the dew tray 13 are heated by the dew tray heater 14 and melted, so that the drainage is smoothly performed.

When the defrosting of the evaporator 5 is completed and the temperature thereof reaches the above + 10 ° C. and the restoration condition is satisfied, the microcomputer 27 performs steps S3 to S3 based on the output of the defrosting restoration sensor 29. In S4, the draining time is calculated from the defrosting time accumulated by the defrosting time timer T2. At this time, defrosting takes a long time, for example, 30
When the accumulated value such as minutes is reached, drainage time is set to 7
If a long time such as minutes is set and conversely defrosting ends early and the integrated value is, for example, 20 minutes, the draining time is set to 3
Set a short time such as minutes.

Then, the microcomputer 27 proceeds to step S5 and sets the drainage time calculated as above as the drainage time timer T3 having its own function. Then, in step S6, the water draining operation is started. In this draining operation, the compressor 1 is stopped and the evaporator 5
The supply of the high temperature refrigerant or the supply of the depressurized liquid refrigerant is stopped. During that time, dew (defrost water) remaining in the evaporator 5 and melted ice blocks fall on the dew tray 13. On the other hand, since the dew tray heater 14 continues to be energized, the defrost water and ice blocks that have fallen from the evaporator 5 are melted and smoothly discharged.

Next, the microcomputer 27 subtracts (counts down) the draining time timer T3 in step S7, and determines in step S8 whether or not the draining time timer T3 has finished counting (whether the count reaches 0). If not, the process returns to step S6 to continue the water draining operation. Then, when the draining time set as described above has elapsed and the subtraction of the draining time timer T3 is completed, the process proceeds from step S8 to step S9 to end the draining operation,
After that, it returns to the cooling operation.

In this way, the microcomputer 27 integrates the defrosting time of the evaporator 5 and calculates the subsequent draining time based on this integrated value, so that the amount of frost on the evaporator 5 can be calculated, for example, in summer. When the defrosting time increases and the defrosting time increases, the draining time also increases, and conversely, when the defrosting amount on the evaporator 5 decreases and the defrosting time decreases in winter, etc., the draining time decreases. By shortening, it becomes possible to set the optimum draining time according to the amount of frost formation. Therefore, it is possible to eliminate unnecessary temperature rise in the refrigerator due to residual frost on the evaporator 5 and excessive drainage time.

Although the evaporator 5 is defrosted by the high temperature gas refrigerant in the embodiment, it is not limited to this and may be defrosted by an electric heater. Needless to say, the present invention is effective not only in the low temperature showcase of the embodiment but also in various freezing and refrigerating equipment.

[0022]

As described in detail above, according to the present invention, the defrosting time of the evaporator is integrated by the time limit means, and the control means calculates the subsequent draining time based on this integrated value. Even if the amount of frost on the evaporator changes due to changes in seasons or the like, it is possible to set the optimum draining time according to the amount of frost. Therefore, it is possible to prevent a decrease in the cooling action due to the remaining frost in the evaporator and an unnecessary increase in temperature due to an excessive drainage time.

[Brief description of drawings]

FIG. 1 is an electric circuit diagram of a low temperature showcase as an example of a cooling device to which a defrosting device of the present invention is applied.

FIG. 2 is a perspective view of the low temperature showcase.

FIG. 3 is a refrigerant circuit diagram of the low temperature showcase.

FIG. 4 is a flowchart showing a program relating to defrost control of a microcomputer.

[Explanation of symbols]

 1 Compressor 5 Evaporator 12 Side pipe 27 Microcomputer 29 Defrost return sensor A Low temperature showcase SV1 Three-way solenoid valve T2 Defrost time timer T3 Drain time timer

Claims (1)

[Claims] 1. A defrosting means for heating an evaporator of a cooling device, a temperature detecting means for detecting a temperature of the evaporator, and a control means for controlling the defrosting means, the control means comprising: After the cooling operation is stopped and the defrosting of the evaporator by the defrosting means is started, the defrosting is performed when the temperature of the evaporator reaches a predetermined defrosting end temperature based on the output of the temperature detecting means. While stopping the heating action of the means, in the cooling device that restarts the cooling operation after leaving a draining time, a time limit means for integrating the defrost time by the defrost means is provided, and the control means is the time limit means. Calculate the draining time based on the integrated value, after the passage of the draining time,
A defroster for a cooling device, which restarts the cooling operation.