JPH0792315B2 - Defrost control device for low temperature showcase - Google Patents

Description

The present invention relates to a defrost control device for a low temperature showcase.

(B) Conventional technology Today, low-temperature showcases that store various foods and drinks in a cold room at a low temperature so that customers can freely take out items from the cold room are widely installed in supermarkets, convenience stores, etc. Has been done.

In this low-temperature showcase, an evaporator and a blower for cooling circulation are arranged in a cooling chamber formed separately from the storage chamber, and cold air cooled by the evaporator forms an air curtain on the open surface of the storage chamber. , Blow out from one discharge port of this open surface, suck from the other blow port, and return to the cooling chamber,
The inside of the refrigerator is maintained in a constant temperature state by being blown out and circulated again so as to be thermally isolated from the outside. By the way, when a customer takes out a product from the warehouse, the air curtain is disturbed and outside air enters. Then, since the cold air is circulated by including the moisture in the outside air, frost is gradually formed on the evaporator by continuing the cooling operation, and the cooling effect of the evaporator is deteriorated. Therefore, it is necessary to periodically stop the cooling operation and perform defrosting.

The cooling operation is stopped by means such as closing a solenoid valve for supplying refrigerant arranged in the refrigerant pipe so that the refrigerant does not flow into the evaporator. On the other hand, in order to perform effective defrosting, two evaporators are used, and when one is being defrosted, the other is cooled so that the air curtain is always formed at the opening of the compartment. Japanese Unexamined Patent Publication (Kokai) No. 57-47176 discloses a refrigerating showcase that prevents the temperature inside the refrigerator from increasing during defrosting.

(C) Problems to be Solved by the Invention In the cooling device disclosed in the above publication, however, the heat of the high-temperature liquefied refrigerant liquefied in the condenser is used to defrost one evaporator, On the other hand, the low temperature liquefied refrigerant after passing through the evaporator
Although the other evaporators are used for cooling by evaporating, the air passing through each evaporator during defrosting and cooling is 1
Since it passes through the same cold air passage, if the defrosting evaporator (for example, 9a) approaches the end of defrosting, the amount of heat spent for defrosting will decrease, and the excess heat will be passed through the cool air circulation air passage by the blower. And passes through the other evaporator 9b being cooled. Therefore, there is a drawback that the cooling effect in the evaporator 9b is reduced.

The present invention, even if the two evaporators are alternately cooled and defrosted,
Cool air generated by heat exchange with the evaporator and warm air from the defrosting heater are circulated so that they do not flow into the other evaporator, ensuring reliable defrosting and the temperature inside the chamber during defrosting. An object of the present invention is to provide a defrosting control device for a low-temperature showcase, which can be appropriately prevented from fluctuating.

(D) Means for Solving the Problems The present invention is directed to a storage room, one side of which is opened so that customers can take out stored products from the opening section, and an opening section provided separately from the storage room. It has a cooling chamber in which an evaporator and a fan for circulating cold air are arranged in a cold air passage facing the cold air discharge port and the cold air suction port at both ends. In a low temperature showcase that forms an air curtain to cool the storage compartment, inside cool air outlets are provided in the opening of the storage compartment to blow out the main cooling airflow and the protective airflow to the outside, respectively. And an outer cool air discharge port, an inner layer duct and an outer layer duct provided by partitioning in the cold air passage so as to respectively communicate with the inner cool air discharge port and the outer cool air discharge port, and in the inner layer duct. It is installed and exchanges heat with the main cold air flow. A main evaporator having a defrosting heater in the front, and an auxiliary evaporator having a defrosting heater that is installed on the windward side of the main evaporator and that is cooled during defrosting of the main evaporator to exchange heat with a protective air flow. A main cooling airflow circulation fan for guiding and circulating a main cooling airflow to the inner layer duct and a protection airflow circulation fan for guiding and circulating a protection airflow to the outer layer duct, and the main evaporator is provided in the vicinity thereof. A thermostat that detects the temperature of the cold airflow controls ON / OFF operation based on the temperature detected, and a thermostat that is provided in the vicinity of the auxiliary evaporator and that detects the temperature of the protective airflow turns it on based on the detected temperature.
A defrost control device for a low-temperature showcase, which is characterized by controlling ON / OFF operation.

(E) Action During cooling, the main evaporator is controlled by the thermostat that detects the temperature of the main cold airflow passing through it so that the cooling operation is stopped or restarted to reach the set internal temperature. . At this time, the auxiliary evaporator is defrosted by the defrosting heater, but the wind warmed by the defrosting heater passes through the outer layer duct and does not enter the inner layer duct with the main evaporator, so Do not reduce the cooling performance. Further, the cold air generated in the main evaporator does not flow into the auxiliary evaporator, and the defrosting of the auxiliary evaporator can be smoothly performed without taking the heat of the heater. On the other hand, when the main evaporator enters the defrosting period and the auxiliary evaporator is operated instead, the protective airflow from the auxiliary evaporator does not enter the inner layer duct where the main evaporator is located, so the main evaporator is defrosted. Insufficient heat of the defrosting heater is prevented, and the main evaporator is defrosted in a short time. In addition, during this defrosting, the auxiliary evaporator that generates a protective airflow instead of the air curtain of the main cold airflow detects the temperature of the protective airflow passing through it by a thermostat, and if the protective airflow temperature becomes too low, the operation will stop. The inside of the refrigerator is maintained within a predetermined temperature range so that the quality of the goods in the refrigerator is not deteriorated.

(F) Example An example of the present invention will be described below with reference to the accompanying drawings.

FIGS. 1 (a) and 1 (b) are structural cross-sectional views of a low temperature showcase according to the present invention, and FIG. 1 (a) is a main evaporator forming an air curtain of an inner layer on an open surface of a compartment during cooling. And (b) shows the state where the auxiliary evaporator is operated in place of the main evaporator during defrosting, thereby forming the air curtain of the outer layer, and the showcase main body 1 is at the lower part. It has a machine room 2 containing a compressor, a condenser, etc.
A cooling chamber 4 is formed above the storage chamber 3 to form a cooling chamber 4.
The upper part is opened so that the customer can insert his or her hand through the upper opening 5 to take out various items displayed and stored in the compartment 3.

A main cold air passage 6 and a protective airflow passage 7 are vertically formed in the back of the chamber 3, and a main evaporator 8 is arranged in the main cold air passage 6. Further, cool air discharge ports 9 and 10 are provided at the tips of the main cool air passage 6 and the protective air flow passage 7, and an inner layer air curtain A ₁ is formed from the cool air discharge port 9 toward the cool air suction port 11 at the time of cooling. At the time of frost, an outer layer air curtain A ₂ is formed from the cool air discharge port 10 toward the cool air suction port 11. Reference numeral 35 is a thermostat which is arranged in front of the cold air discharge port 9 to detect the temperature of the cold air after passing through the main evaporator 8 and control the ON / OFF operation of the main evaporator 8.

In the cooling chamber 4, an auxiliary evaporator 12 is arranged on the side close to the cold air suction port 11 and, in the rear thereof, as shown in FIG. 2, for circulating cold air through the main cold air passage 6. Main cooling air circulation fans 13a, 13a and a protective airflow circulation fan 14 for circulating the protective airflow through the protective airflow passage 7 are provided. Main cooling air circulation fan 13a,
13a and the protective airflow circulation fan 14 are partitioned by partition plates 16 in the fan case 15 and are arranged independently. Then, the cool air inlets 17, 17 and the protective air flow inlet 18 are opposed to each other corresponding to the respective fans 13a, 13a, 14 and the inner layer duct 19 through which the main cold air flow generated in the main cold air passage 6 and the protective air flow passage 7 respectively passes.
An outer layer duct (20) through which the protective air flow passes is divided into sections. Further, a defrosting heater 21 is provided at a front portion (upwind side) of the main evaporator 8. Therefore, when the cool air circulation fans 13a, 13a are driven and rotated, the cool air circulates according to the solid arrow shown in FIG. It is isolated by and is maintained at a constant low temperature. The operation of the main evaporator 8 is stopped during defrosting, but the auxiliary evaporator 12 is operated instead,
At that time, according to the solid line arrow shown in FIG. 1 (b), the protective air flow circulates to form the outer layer air curtain, and the fluctuation of the temperature in the storage chamber 3 is suppressed. Further, the defrosting heater 21 is energized to defrost the main evaporator 8.

Here, by operating the auxiliary evaporator 12, a protective airflow is formed in the upper surface opening 5 of the storage chamber 3 to maintain a low temperature in the storage, but the cold air generated in the auxiliary evaporator is defrosted as in the conventional case. The protective airflow, which is low in temperature when it seems to pass through the main evaporator inside, deprives the heat of the defrosting heater 21 and becomes a shortage of heat source, resulting in insufficient defrosting of the main evaporator 8 and frost. There is a risk of generating the rest.

However, in the present invention, the cold air that has exchanged heat with the auxiliary evaporator 12 and the cold air that has exchanged heat with the main evaporator 8 are respectively provided in the protective airflow circulation fan 14 and the main cold airflow circulation fans 13a and 13a in different passages. In order to prevent incomplete defrosting and cooling from occurring, the outer layer duct 20 and the inner layer duct 19 are prevented from flowing and mixing. Then, during the cooling operation by the auxiliary evaporator 12,
The cooling operation and the stop control of the auxiliary evaporator 12 are performed so as to maintain the temperature inside the refrigerator when the main evaporator 8 was used.

Therefore, a thermostat 22 is arranged on the windward side of the auxiliary evaporator 12, and the thermostat 22 closes or opens a solenoid valve for refrigerant supply (described later) arranged in the refrigerant circuit of the auxiliary evaporator 12 to open or close the auxiliary evaporator. Controls 12 ON / OFF.

FIG. 3 shows the refrigerant piping diagram, in which the gas refrigerant discharged from the compressor (not shown) is liquefied through the condenser (not shown), and the liquefied refrigerant is divided into two systems, and the respective lines 24 and 25 are provided. Flowing. A main evaporator 8 is arranged in the pipe line 24, and a refrigerant supply solenoid valve 26 and an expansion valve 27 are arranged on the inlet side thereof. Similarly, the pipeline 25 is provided with the auxiliary evaporator 12, and a refrigerant supply solenoid valve 28 and an expansion valve 29 on the inlet side thereof. Solenoid valve for refrigerant supply here
The opening and closing of 26 is controlled by a thermostat 35 provided inside the refrigerator, while the opening and closing of the refrigerant supply solenoid valve 28 is controlled by the thermostat 22.

FIG. 4 shows an overall control circuit diagram, where 30 is an AC power supply and 31 is a compressor (CM), which are connected in series with a low-voltage switch 32.

A defrosting timer 33 closes the contact 33A when the set defrost time is reached, and excites the first relay 34 (1X) connected in series to the contact 33A. 34A is a relay contact of the first relay 34, which is normally closed to the a side and switches to the b side when the first relay 34 is excited. The thermostat 35 (TH), which is arranged in the main cooling passage 6 and opens / closes according to the temperature inside the chamber, and the solenoid valve for refrigerant supply described above on the side a.
26 (SV ₁ ) is connected in series. Therefore, when the inside of the refrigerator reaches the set upper limit temperature, the thermostat 35 closes and opens the refrigerant supply electromagnetic valve 26 to allow the refrigerant to flow into the main evaporator 8 to perform a cooling action, and when the temperature reaches the lower limit temperature, the thermostat 35 is opened. Closes the electromagnetic valve 26 for supplying the refrigerant, stops the supply of the refrigerant, and stops the operation of the main evaporator 8. Further, a fan motor 36 (FM) that drives the main cold airflow circulation fans 13a, 13a and the protective airflow circulation fan 14 is connected to the AC power supply 30, and these fan motors are constantly driven to rotate. On the other hand, the thermostat 22 (HT
H) and the solenoid valve 28 (SV ₂ ) for supplying refrigerant are connected in series. Therefore, during defrosting, the refrigerant supply solenoid valve 28 is energized and opened by switching the contact 34A, the refrigerant is flown to the auxiliary evaporator 12 for cooling operation, and the protective airflow circulation fan 14 is rotated to generate the protective airflow. The thermostat 22 detects the temperature of the protective airflow while being formed in the upper opening 5 of the No. 3 and is turned off (closed) when the temperature becomes too low to reach the set lower limit temperature (± 0 ° C), and the temperature rises. Maximum temperature (±
When it reaches 5 ℃, it turns on (open circuit) and each solenoid valve for refrigerant supply 28
Is controlled to operate and stop the auxiliary evaporator 12.

21 is a defrosting heater (DH), which is connected to the b side
It is connected in series with the relay contact 38A of the relay 38 (2X) and generates heat when energized during defrosting. A defrosting heater heating protector 39 is connected to the second relay 38, and opens in a heated state to provide safety protection for shutting off the defrosting heater 21 from the power source. 40 is a dew-proof heater.

The operation of the above configuration will be described below.

During normal cooling operation, the first relay 34 does not operate and the contact 34
A is switched to the a side and held. Therefore, the solenoid valve 26 for supplying the refrigerant is opened / closed by turning on / off the thermostat 35 (TH) to stop the supply of the refrigerant to the main evaporator 8, and the main evaporator 8 is thermo-controlled. When the defrosting time comes, the defrosting timer 33 operates and the first relay 34 operates by closing the contact 33A, the contact 34A switches to the b side, the operation of the main evaporator 38 is stopped, and the first 2 When the relay 38 is operated and the contact 38A is closed, the defrosting heater 21 generates heat to defrost the main evaporator 8. Further, the solenoid valve 28 for supplying the refrigerant is opened, and the auxiliary evaporator 12 is in the cooling operation. Fan motor 36
(FM) continues to rotate, and the protective airflow circulation fan 14 operates to circulate the protective airflow A ₂ . And thermostat
The auxiliary evaporator 12 is also thermo-controlled by turning ON / OFF the 22 according to the temperature of the protective air flow. At this time, the auxiliary evaporator 12
The low temperature protective airflow generated at
Since it does not enter the inner layer duct 19 having the main evaporator 8 for defrosting, the heat of the defrosting heater 21 is not taken away and frost residue of the main evaporator 8 is prevented, and the inside of the chamber 3 is protected by the protective air flow. It protects against the influence of temperature and prevents damage to the product.

The operating states of the main circuit components shown in FIG. 4 are shown in the table below.

(G) Effect of the Invention As described above, according to the present invention, when the main evaporator that forms the air curtain in the open part of the normal storage compartment and controls the cooling of the interior to a predetermined temperature is operated at the time of defrosting, it is operated. An auxiliary evaporator is provided to prevent damage to the stored products by forming a protective air flow similar to that of an air curtain, and the cool air that has exchanged heat with the main evaporator is fed to the outer duct by the main cold air flow circulation fan, and the auxiliary evaporator. The cool air that has been heat-exchanged with is circulated by flowing separately to the inner layer duct with a protective airflow fan, and is careful not to deteriorate the heat exchange between the evaporators during cooling and defrosting. Since the auxiliary evaporator is controlled to be turned ON / OFF at the temperature of the protective airflow, the heat source for defrosting the main evaporator during defrosting is deprived of heat by the low-temperature protective airflow, and the heat source becomes insufficient. Is prevented and does not cause frost residue. Therefore, reliable defrosting and prevention of deterioration of stored products during defrosting can be appropriately achieved.

[Brief description of drawings]

FIG. 1 (a) is a schematic structural diagram of a low temperature showcase of the present invention showing a state in which the main evaporator is operated to form an inner-layer air curtain, and FIG. 1 (b) is a main evaporator in defrosting. 2 is a schematic structural diagram of the low-temperature showcase showing a state in which a protective airflow is formed in the auxiliary evaporator operated in place of
The figure shows a duct installed in the cooling chamber where the passages for the cool air and the protective air flow are formed independently, and the related configuration of the main cold air flow circulation fan and the protective air flow circulation fan that are arranged at the duct inlet. FIG. 3 is a perspective view showing the structure of a refrigerant pipe, and FIG. 4 is a control circuit diagram. 3 ... storage room, 4 ... cooling room, 8 ... main evaporator, 12 ... auxiliary evaporator, 13a, 13a ... main cooling air circulation fan, 14 ...
Protective air flow circulation fan, 21 ... Defrost heater, 22 ... Thermostat (HTH).

Claims (1)

[Claims] 1. A storage room having one surface opened so that customers can take out stored products from the opening, and a cold air discharge port and a cold air suction port provided at both ends of the opening part, which are provided separately from the storage room. A cooling chamber in which an evaporator and a fan for circulating cold air are arranged in the cold air passage facing the above, and the fan forms an air curtain of a cold air flow in the open portion of the storage chamber. In a low temperature showcase that is designed to cool, an inner cool air discharge port and an outer cool air discharge port provided to blow out a main cool air flow inside and a protective air flow outside, respectively, in the open portion of the compartment, An inner layer duct and an outer layer duct, which are formed by partitioning so as to communicate with the inner cool air discharge port and the outer cool air discharge port, respectively, in the cold air passage, and heat exchange with a main cold air flow installed in the inner layer duct. And main steam with defrosting heater A generator, an auxiliary evaporator that is installed on the windward side of the main evaporator and that performs a cooling operation during defrosting of the main evaporator to exchange heat with the protective airflow and also has a defrosting heater, and the main cold airflow to the inner layer. A main cold airflow circulation fan for guiding and circulating the duct and a protection airflow circulation fan for guiding and circulating a protective airflow to the outer layer duct, and a thermostat for detecting the temperature of the main cold airflow provided in the vicinity of the main evaporator. A low temperature show characterized by performing ON / OFF operation control based on the detected temperature, and ON / OFF operation control based on the detected temperature by a thermostat that is provided in the vicinity of the auxiliary evaporator and detects the protective airflow temperature. Defrost control device for the case.