JPH05203329A - Refrigeration device - Google Patents

Abstract

PURPOSE:To enable positive defrosting and drain dripping while preventing undesired temperature rise in a storage room by carrying out defrosting operation control according to an evaporator temp. and heating of a base plate according to a temp. thereof for a period of time such as closed hours of a shop, etc. CONSTITUTION:In operation of the title device, for a specified period of time such as open hours of a shop, etc., a 1st control means is operated whenever a timer 32 detects a given time. That is, a two-way valve 25 is opened, and hot refrigerant from a compressor is directly supplied to an evaporator through a bypath 24 to thaw frost on a surface of the evaporator and drop it on a base plate of a storage room as drain. A temperature detected by an evaporator temp. sensor 13 us compared with a set value, and when it reaches the set value, the two-way valve 25 is closed. Then, for a period of time except a specified one such as closed hours of a shop, etc., a 2nd control means is operated; the two-way valve 25 is opened to start defrosting operation, and an electric heater 11 is energized to heat the base plate up to a set temp. and drop drain onto a drain pan.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerating apparatus used for storing fresh foods.

[0002]

2. Description of the Related Art As a refrigerating device for storing fresh food such as fish and vegetables, a refrigerating cycle in which a compressor, a condenser, a decompressor and an evaporator are sequentially connected is provided, and the refrigerating cycle's evaporator is accommodated. There is one that is provided in a refrigerator and is cooled by circulating air in the refrigerator through an evaporator.

In this refrigeration system, frost gradually adheres to the surface of the evaporator as cooling progresses, and the cooling effect is impaired if the frost is left as it is. Therefore, it is necessary to regularly perform the defrosting operation on the evaporator.

This defrosting operation is so-called hot gas defrosting, and is an operation in which the high temperature refrigerant discharged from the compressor is directly supplied to the evaporator and the frost is melted by the heat of the high temperature refrigerant. The drain generated by this defrosting operation hangs down on the bottom plate of the storage and is discharged to the outside from the drain discharge port of the bottom plate.

An electric heater is provided near the drain discharge port on the bottom plate of the storage, and the electric heater is operated at the same time as the defrosting operation to eliminate freezing of the drain and ensure reliable drain discharge. There is.

A temperature sensor is further attached to the bottom plate of the storage, and the defrosting operation and the operation of the electric heater are terminated when the temperature detected by the temperature sensor reaches a set value, for example, 10 ° C.

[0007]

However, in the above refrigerating apparatus, it takes a certain amount of time for the bottom plate temperature of the storage to reach the set value (10 ° C.), so the temperature of the evaporator rises greatly during that time. Can reach 60 ℃. If this happens, the temperature inside the refrigerator will rise, which may adversely affect the preservation of the contents.

The present invention takes the above circumstances into consideration,
The purpose is to provide a highly reliable refrigerating device capable of performing reliable defrosting and drainage discharge while preventing unnecessary temperature rise in the storage cabinet, and always enabling stable cooling. It is in.

[0009]

The refrigerating apparatus of the present invention comprises:
An evaporator for the refrigeration cycle is provided in the storage, and a drain discharge port is provided on the bottom plate of the storage. Furthermore, an electric heater and a bottom plate temperature sensor are provided on the bottom plate of the storage,
An evaporator temperature sensor is provided in the evaporator. Also, the first defrosting operation for the evaporator and the electric defrosting operation for the evaporator are started simultaneously with the start of the defrosting operation for the evaporator and the operation of the electric heater, and the operation is ended when the temperature detected by the evaporator temperature sensor reaches a set value. The heater operation is started at the same time, the defrosting operation is ended when the temperature detected by the evaporator temperature sensor reaches the set value, and the operation of the electric heater is ended when the temperature detected by the bottom plate temperature sensor reaches the set value. And a second control means. Of these, the control of the first control means, which is a one-sensor system, is periodically executed in a predetermined time period, and
The control of the second control means, which is a sensor method, is executed at least once in a time period different from the predetermined time period.

[0010]

In a predetermined time zone, for example, the business hours of a store, the defrosting operation and the operation of the electric heater are started simultaneously at the same time, and are finished when the evaporator temperature reaches the set value.

In a time zone different from this, for example, in the non-business hours of a store, the defrosting operation and the heater operation are started at least once, and the defrosting operation is ended when the evaporator temperature reaches the set value. Then, the operation of the electric heater is terminated when the bottom plate temperature of the storage reaches the set value.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a main body of a refrigerating machine, which has an opening 1a at a position which occupies an area of approximately 2/3 of an upper portion of a front surface, and a door 2 is pivotably supported so as to close the opening 1a. It A ventilation grill 3 is provided on the lower part of the front surface of the main body 1, and inside the ventilation grill 3 is a machine room 10b described later.
Is secured.

A housing 4 is provided in the main body 1 at a position corresponding to the door 2. The housing 4 is surrounded by a heat insulating material 5 attached to the inner peripheral surface of the main body 1 and a partition wall 6 arranged inside the heat insulating material 5 with a predetermined gap.

A gap between the heat insulating material 5 and the partition wall 6 serves as an air passage 7 around which the housing 4 is wound in the vertical direction. An evaporator 8 is provided on the back side of the ventilation passage 7, and a cooling fan 9 is provided above the evaporator 8. The cooling fan 9 serves to circulate the air in the storage 4 through the evaporator 8 as indicated by the arrow. Although not shown, the inner peripheral surface of the heat insulating material 5 is covered with a metal plate having good thermal conductivity, and a bottom plate 10 which is the same metal plate is provided at the bottom of the storage case 4.

A drain discharge port 10a is formed in the bottom plate 10 at a position corresponding to the evaporator 8. The drain discharge port 10a is for discharging the drain dripping from the evaporator 8 to the outside of the storage case 4. An electric heater 11 and a bottom plate temperature sensor 12 are attached to the bottom plate 10 near the drain outlet 10a. An evaporator temperature sensor 13 is attached to the refrigerant outlet side of the evaporator 8. A thermistor is used for each of the bottom plate temperature sensor 12 and the evaporator temperature sensor 13. A shelf plate 14 for placing food on the food storage 4 is detachably attached in several stages.

On the other hand, a condenser 15 is provided inside the ventilation grill 3 in the machine room 10b, and a condenser fan 16 is provided opposite to the condenser 15. The condenser fan 16 has a function of sucking the air outside the main body 1 through the ventilation grill 3 and passing it through the condenser 15 as indicated by an arrow. Further, a drain tray 17 is provided in the machine room 10b,
A compressor 18 is provided on the drain pan 17.

The drain tray 17 is located at a position corresponding to the drain outlet 10a, and a drain hose 19 having one end attached to the drain outlet 10a passes through the heat insulating material 5 and hangs down to the drain tray 17. This drain hose 19
Serves to guide the drain to the drain pan 17. The structure of the refrigeration cycle and the control circuit is shown in FIG.

A condenser 15 is connected to the discharge port of the compressor 18, and the evaporator 15 is connected to the condenser 15 via a dryer 21 and a capillary tube 22 which is a decompressor. The suction port of the compressor 18 is connected to the evaporator 8 via the accumulator 23.

One end of the bypass 24 is connected to the connecting portion between the compressor 18 and the condenser 15, and the other end of the bypass 24 is connected to the connecting portion between the capillary tube 22 and the evaporator 8. An electromagnetic two-way valve 25 is provided in the middle of the bypass 24.

A control unit 30 is composed of a microcomputer and its peripheral circuits. The controller 30 includes an electric heater 11, a bottom plate temperature sensor 12, and an evaporator temperature sensor 1.
3, cooling fan 9, condenser fan 16, compressor 1
8, the two-way valve 25, the internal temperature sensor 31, the timer 32, and the operating device 33 are connected. The internal temperature sensor 31 is
The temperature Ta in the storage 4 is detected. The operation device 33 is for inputting various operating conditions. The control unit 30 has the following functional means. (1) A means for controlling the operation of the compressor 18, the condenser fan 16, and the cooling fan 9 in response to the operation start / stop operation of the operation device 33. (2) Means for comparing the internal temperature set by the operation device 33 with the detected temperature Ta of the internal temperature sensor 31 during operation, and controlling the operation of the compressor 18 according to the comparison result.

(3) The defrosting operation for the evaporator 18 (= opening of the two-way valve 25) and the operation of the electric heater 11 are started at the same time, and the detected temperature Te of the evaporator temperature sensor 13 is set to a set value, for example, 15 ° C. The first control means of the one-sensor type that ends when the temperature reaches the.

(4) The defrosting operation for the evaporator 18 (= opening of the two-way valve 25) and the operation of the electric heater 11 are started at the same time, and the defrosting operation is performed while the temperature Te detected by the evaporator temperature sensor 13 is the set value. For example, the second control means of the two-sensor type that ends when the temperature reaches 15 ° C. and ends when the temperature To detected by the bottom plate temperature sensor 12 reaches a set value, for example, 10 ° C.

(5) The control of the first control means is periodically executed in a predetermined time zone (= daytime business hours), for example, every four hours, and the control of the second control means is performed at a time different from the predetermined time zone. A control means that is executed at least once in a zone (= non-business hours at night). Next, the operation of the refrigerating apparatus thus configured will be described. First, when the operation start operation is performed by the operation device 33, the operations of the compressor 18, the condenser fan 16, and the cooling fan 9 are started.

When the compressor 18 is started, the compressor 18
The refrigerant discharged from the condenser enters the condenser 15. This condenser 1
In 5, the refrigerant is deprived of heat by the air blown by the condenser fan 16 and condensed.

The refrigerant having passed through the condenser 15 enters the evaporator 8 through the dryer 21 and the capillary tube 22. In the evaporator 8, the refrigerant takes heat from the air blown by the cooling fan 9, that is, the air in the storage case 4 to evaporate. This allows
The inside of the storage 4 is cooled. The refrigerant vaporized in the evaporator 8 passes through the accumulator 23 and is sucked into the compressor 18. During this operation, the compressor 1 is adjusted so that the temperature Ta detected by the internal temperature sensor 31 matches the internal temperature set by the operating device 33.
The operation of No. 8 is on / off controlled. During operation, the timer 32 counts the elapsed time. When the count time of the timer 32 reaches 4 hours, the control of the first control means shown in FIG. 4 is executed.

That is, the two-way valve 25 opens and the compressor 18
The high-temperature refrigerant discharged from is directly supplied to the evaporator 18 through the bypass 24. Due to this hot gas defrosting, the frost adhering to the surface of the evaporator 18 is melted, and it becomes drain and drops onto the bottom plate 10 of the storage case 4.

At the same time as the start of this defrosting operation, the electric heater 1
Operation 1 is started and the bottom plate 10 is heated. This heating is for preventing the freezing of the drain at the drain outlet 10a as much as possible.

Therefore, the drain dropped on the bottom plate 10 easily and surely flows into the drain discharge port 10a and is guided from there through the drain hose 19 to the drain tray 17 of the machine room 10b.

In this case, since the heat radiation effect in the condenser 15 is unnecessary, the operation of the condenser fan 16 is stopped. Further, the operation of the cooling fan 9 is stopped in order to prevent hot air from circulating in the storage case 4.

Further, the temperature T detected by the evaporator temperature sensor 13
e is taken in and compared with the set value of 15 ° C. Although it depends on the amount of frost, the evaporator temperature Te reaches the set value of 15 ° C. in a short time of 2 to 3 minutes.

When the evaporator temperature Te reaches the set value of 15 ° C.,
The two-way valve 25 is closed, and the defrosting operation for the evaporator 8 ends. At the same time, the operation of the electric heater 11 is stopped and the heating of the bottom plate 10 is completed. During the defrosting operation and the operation of the electric heater 11, the compressor 18 continues to operate without stopping.

Here, the set value for the evaporator temperature Te is 15
The temperature of ° C prevents the low-pressure side pressure of the refrigeration cycle from rising abnormally, and thus prevents the high-pressure side pressure from rising abnormally, and it is possible to ensure sufficient safety of the equipment constituting the refrigeration cycle.

Upon returning to the normal operation, the operation of the condenser fan 16 is restarted immediately, but the operation of the cooling fan 9 is delayed after 3 minutes based on the timing of the timer 32. This copes with the fact that the temperature of the evaporator 8 does not immediately drop, and prevents the problem that hot air circulates in the storage case 4. Thus, during the business hours, the defrosting operation and the bottom plate heating by the first control means are repeatedly performed every 4 hours.

As described above, during the business hours, the heating of the bottom plate 10 is not so important and the evaporator temperature T
By repeatedly executing the defrosting operation control for a short time according to e, it is possible to reliably prevent the evaporator 4 from increasing while preventing an unnecessary temperature increase in the evaporator 8 and thus preventing an unnecessary temperature increase in the storage case 4. Defrosting can be performed. On the other hand, in the non-business hours, the control of the second control means shown in FIG. 5 is executed only once in the predetermined time based on the count of the timer 32. That is, the two-way valve 25 is opened and the defrosting operation for the evaporator 8 is started. At the same time, the electric heater 11
The operation of is started and the bottom plate 10 is heated.

Therefore, the drain dropped on the bottom plate 10 easily and surely flows into the drain discharge port 10a and is guided from there through the drain hose 19 to the drain tray 17 of the machine room 10b.

In this case, the temperature Te detected by the evaporator temperature sensor 13 is taken in and compared with the set value 15 ° C.
Further, the detection temperature To of the bottom plate temperature sensor 12 is taken in,
It is compared with the set value of 10 ° C.

When the evaporator temperature Te reaches the set value of 15 ° C.,
The two-way valve 25 is closed, the compressor 18 is stopped, and the evaporator 8
However, the defrosting action continues for a while. At this time, the bottom plate temperature To is slower than the temperature Te of the evaporator 8 and does not reach the set value 10 ° C. yet.
Therefore, the bottom plate heating by the operation of the electric heater 11 continues. After that, when the bottom plate temperature To reaches the set value 10 ° C., the operation of the electric heater 11 is stopped, and the bottom plate heating is completed.

As described above, during the non-business hours, the defrosting operation control for a short time according to the evaporator temperature Te is executed,
By performing the bottom plate heating in accordance with the bottom plate temperature To with emphasis, not only the reliable defrosting but also the drain discharge port 1
It is possible to reliably discharge drainage at 0a. Moreover,
Since this drain discharge effect can be continued until business hours, stable cooling is always possible and reliability can be improved.

In the graph of FIG. 3, (A) shows temperature data when the control of the first control means is executed, and (B) shows temperature data when the control of the second control means is executed. It is a thing. The first control means and the second control means will be described below with reference to FIG.
The temperature characteristic of the defrosting control of the control means will be described.

In the conventional device, when defrosting is started by opening the two-way valve and energizing the electric heater, the defrosting operation is performed until the bottom plate temperature reaches 10 ° C. Therefore, as shown by the conventional Te in the graph, While the evaporator temperature Te rises excessively up to about 40 ° C., the first control means starts the defrosting by opening the two-way valve and energizing the electric heater.
When only this is detected and this temperature reaches 15 ° C., the electric heater 11 is stopped and the two-way valve 25 is closed. At this time, since the compressor 18 is continuously driven, the cooling operation is restarted, and the evaporator temperature Te once rises as shown by Te (A) on the graph, and then the normal cooling operation is performed in a short time. The temperature will converge to the set temperature. On the other hand, the bottom plate temperature To rises to about −10 ° C. and then gradually falls as shown by To (A) on the graph. In such a first control means, as shown in Ta (A) on the graph, the rise in the temperature inside the chamber is small,
Suitable for defrost control during business hours.

On the other hand, in the second control means, the two-way valve 25
When defrosting is started by opening the battery and energizing the electric heater 11, both the evaporator temperature Te and the bottom plate temperature To are detected,
Evaporator temperature T whose temperature rising speed is faster than the bottom plate temperature To
When e first reaches 15 ° C, the two-way valve 25 is closed. Since the compressor 18 is temporarily stopped in response to the closing of the two-way valve 25, the defrosting action continues for a while without exerting a cooling action as shown in the rising process of Te (B) on the graph. To do. On the other hand, even after the two-way valve 25 is closed, the electric heater 11 continues to operate until the bottom plate temperature To having a slow temperature rising rate reaches 10 ° C. Then, when the bottom plate temperature To reaches 10 ° C., the electric heater 11 is stopped, and accordingly the compressor 1 is stopped.
Since the operation of No. 8 is restarted, the evaporator temperature Te converges to the set temperature during the normal cooling operation in a short time as shown by the descending progress of Te (B) on the graph, and the bottom plate temperature To is on the graph To. As shown in the descending process of (B), the temperature rises to about 10 ° C and then gradually decreases.

In such a second control means, the compressor 18 is once stopped to continue the defrosting action while suppressing the excessive rise of the evaporator temperature Te, and at the same time, the defrosting effect of the electric heater 11 is increased. Therefore, sufficient defrosting is possible,
Further, as shown in Ta (B) on the graph, the rise of the temperature inside the refrigerator is slightly higher than that of the first control means, but since it can be made lower than that of the conventional device, it is suitable for performing sufficient defrosting at night. ing.

[0044]

As described above, according to the present invention, the heating of the bottom plate is not so important in a predetermined time zone.
The defrosting operation control according to the evaporator temperature is repeatedly executed, and in other time zones, the bottom plate heating according to the bottom plate temperature is emphasized while executing the defrosting operation control according to the evaporator temperature. Since it is configured to be performed in the above-described manner, it is possible to perform reliable defrosting and drain discharge while preventing unnecessary temperature rise in the storage cabinet, and it is possible to provide a highly reliable refrigeration system that enables stable cooling at all times. ..

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing the configuration of an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a refrigeration cycle and a control circuit of the same embodiment.

FIG. 3 is an evaporator temperature Te and a bottom plate temperature T in the same embodiment.
The figure which shows the example of o and the temperature Ta in a warehouse.

FIG. 4 is a time chart for explaining the control of the first control means in the embodiment.

FIG. 5 is a time chart for explaining the control of the second control means in the embodiment.

[Explanation of symbols]

1 ... Main body, 2 ... Door, 4 ... Storage box, 8 ... Evaporator, 10 ...
Bottom plate, 10a ... Drain discharge port, 11 ... Electric heater, 12
... bottom plate temperature sensor, 13 ... evaporator temperature sensor, 18 ... compressor, 24 ... bypass, 25 ... two-way valve.

Claims (1)

[Claims] 1. A refrigeration cycle in which a compressor, a condenser, a decompressor, and an evaporator are sequentially connected, a storage box provided with the evaporator, and a drain discharge port provided on a bottom plate of the storage box.
An electric heater and a bottom plate temperature sensor provided on the bottom plate of the storage, an evaporator temperature sensor for detecting the temperature of the evaporator, a defrosting operation for the evaporator, and an operation of the electric heater are started at the same time. The first control means that ends when the temperature detected by the evaporator temperature sensor reaches a set value, and the defrosting operation for the evaporator and the operation of the electric heater are simultaneously started, and the defrosting operation is performed for the evaporator. Control of the second control unit and the first control unit that ends when the temperature detected by the temperature sensor reaches a set value and ends the operation of the electric heater when the temperature detected by the bottom plate temperature sensor reaches the set value. Refrigeration, characterized in that it comprises a control means for executing the control of the second control means at regular intervals in a predetermined time zone and at least once in a time zone different from the predetermined time zone. Location.