JPH0536707B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a method for defrosting a plurality of low-temperature show cases of forced circulation type cold air each equipped with an evaporator and a blower fan.

(b) Conventional technology Japanese Patent Publication No. 53-17781 (JPC68A421) states,
a plurality of evaporators, a defrost device associated with each of the evaporators, and associated with each of the evaporators, the defrost device associated with the evaporator is operable when the evaporator requires defrosting; a sensing device for determining the status of the defroster, and a sensing device for sequentially scanning in a predetermined order whether or not each defrosting device for each of the evaporators is in an operable state; a control device that sequentially activates only the defrost devices that are enabled, and a scanning of the control device when the control device scans one defrost device that is enabled by the sensing device; a scanning interruption device that suspends operation until said one defrost device completes a defrosting operation; and a scanning interruption device that causes said one defrost device to stop its defrosting operation when said one defrost device completes defrosting; and a time delay controller for restarting and delaying restart of an evaporator associated with the one defrost device.

(c) Problems to be solved by the invention The plurality of evaporators of the above-mentioned refrigeration system are arranged one by one corresponding to the cold air circulation path of a plurality of low-temperature show cases installed in stores such as supermarkets. However, due to the layout of the store, multiple low-temperature show cases whose storage chambers are cooled to the same temperature are arranged in a straight line so that adjacent storage chambers communicate with each other.

Therefore, since there is no partition between the storage chambers of adjacent low-temperature show cases, when one low-temperature show case is cooling and the adjacent low-temperature show case starts defrosting, the storage room of one low-temperature show case will be removed. Cold air flows into the storage chamber of the other low-temperature case, and the temperature in the storage chamber of the low-temperature case during defrosting drops, slowing down the defrosting of the evaporator and making it impossible to defrost the evaporator during the defrosting time. A problem arose.

(d) Means for solving the problem The present invention aims to solve the above-mentioned problem, and as a means for solving the problem, storage chambers are arranged in a straight line so that the respective storage chambers communicate with each other in the horizontal direction. The cold air circulation path of the low-temperature show case is equipped with an evaporator with a solenoid valve connected to the refrigerant inlet side, a defrost device that thaws the frost adhering to the evaporator during defrosting, and a blower fan that operates constantly. At the start, all defrosting devices are energized and all solenoid valves are closed at the same time, and at the end of defrosting, power is cut off to the defrosting device of each evaporator individually, and the power is cut off. To provide a defrosting operation method for a low-temperature show case in which a solenoid valve corresponding to a defrosting device is sequentially opened.

(E) Effect Since all the evaporators of each low-temperature show case start defrosting at the same time, even if cold air flows back and forth between the storage rooms of adjacent low-temperature show cases, the temperature of each storage room remains approximately the same. Even if the amount of frost formed on each evaporator is slightly different, defrosting can be completed in almost the same amount of time.

In addition, in order to cut off the power to the defrost device of each evaporator individually for each evaporator, and to sequentially open the solenoid valves corresponding to the defrost devices whose power was cut off, the end of defrosting is determined by the evaporator with a large amount of frost. There is no need to match the evaporator to the evaporator, and the evaporator that has finished defrosting first can be returned to cooling operation in order.

(F) Embodiments Below, embodiments of the present invention will be described based on the drawings. 1A to 1E are front-open type low-temperature show cases installed in stores such as supermarkets, and each low-temperature show case 1A to 1E has a linear shape. They are installed horizontally in a row. As shown in FIG. 2, the main body of each of the low-temperature show cases 1A to 1E is composed of a heat insulating wall 3 having an opening 2 for storing and taking out products at the front, and an appropriate distance is left from the inner surface of the heat insulating wall 3. By arranging partition plates 4, storage chambers 6A to 6E are provided with a plurality of shelves 5, and both outlet and suction ports 7 and 8 are provided facing each other along both upper and lower edges of the opening 2, A cold air circulation path 10 whose left and right sides are covered with blocking plates 9 is formed. Each of the low-temperature storage cases 1A to 1E has storage chambers 6A to 6.
They are connected as shown in FIG. 1 using an appropriate connecting device so that E can communicate with each other, and a pair of left and right side plates 11 are attached to the outermost left and right sides.

Each of the cold air circulation paths 10 of each of the low-temperature cases 1A to 1E includes evaporators 12A to 12 shown in FIG.
2, electric heaters 13A to 13E serving as defroster devices located on the air inlet side of each evaporator, and a blower fan 14 that is constantly operated are arranged as shown in FIG. Since the blower fan 14 is constantly operated, the air in the cold air circulation path 10 is circulated as shown by the arrow, and an air curtain CA is formed in the opening 2. During cooling when the reduced pressure liquid refrigerant is supplied to the evaporators 12A to 12E, the air curtain CA becomes cold because it is formed by the cold air heat exchanged by the evaporators 12A to 12E, and becomes cold in each storage room. 6A to 6E are cooled, and the supply of reduced pressure liquid refrigerant to each evaporator 12A to 12E is interrupted, and each electric heater 13
During defrosting when electricity is applied to A to 13E, the temperature will gradually rise.

FIG. 3 shows a refrigerant circuit of a refrigeration system, and each of the evaporators 12A to 12E corresponds one-to-one with the electromagnetic valves 15A to 15E and the expansion valves 16A to 16E as pressure reducing devices, respectively, forming systems A to E. are connected in series. The systems A to E correspond to the low-temperature show cases 1A to 1E, respectively, and are connected in parallel with each other. The refrigerant circuit includes a refrigerant compressor 17 and a water-cooled or air-cooled condenser 1.
8. Each system A to E, the gas-liquid separator 19 is connected to a high pressure gas pipe 20, a high pressure liquid pipe 21, and a high pressure liquid branch pipe 22A to 22.
E, low pressure liquid pipes 23A to 23E, low pressure gas branch pipe 24
A to 24E and low pressure gas pipes 25 are also connected in an annular manner to form a closed circuit, and during cooling, the refrigerant is circulated as shown by the arrows. 26
A to 26E are controllers corresponding to the respective systems A to E, and these controllers include the respective electric heaters 13A to 1.
3E, each of the electromagnetic valves 15A to 15E, and each temperature sensor 27A to 27E disposed on the air outlet side of each of the evaporators 12A to 12E are electrically connected.

FIG. 4 shows an electric circuit, and the controllers 26A to
26E is a control section 28A to 28E equipped with a timer, an A-D converter, a comparator, etc., a power supply section 29A to 29E that applies a low voltage to the control section, and a controller for controlling each of the electric heaters 13A to 13E. 1 relay 30
A to 30E, and second relays 31A to 31E for controlling the respective electromagnetic valves 15A to 15E. Said first relay and second relay 30A-3
0E, 31A to 31E are electromagnetic coils 32A to 32
E, 33A to 33E and contact pieces 34A to 34E, 35A to 35E that are opened and closed by this electromagnetic coil.
It is equipped with

Each of the low-temperature shower cases 1A to 1E alternately repeats a cooling operation and a defrosting operation according to a timer signal from each controller 26A to 26E. The time ratio of cooling operation and defrosting operation can be changed arbitrarily, for example, after 3 hours of cooling operation, the time ratio of
It is set to perform a defrosting operation for a minute, and if the value detected by the temperature sensors 27A to 27E during the cooling operation is a preset lower limit value, for example -5°C, a signal from each control unit 28A to 28E is sent. Based on this, the corresponding electromagnetic coils 33A to 33E of the second relays 31A to 31E are de-energized, and each contact piece 34
A to 34E open, each solenoid valve 15A to 15E is closed, and the supply of reduced pressure liquid refrigerant to each evaporator 12A to 12E is interrupted, which is the so-called thermo-off, and the value detected by the temperature sensor 27A to 27E is If the set upper limit value is, for example, -1°C, the corresponding electromagnetic coils 33A to 33A of the second relays 31A to 31E are activated based on signals from each control unit 28A to 28E.
33E is energized to close each contact piece 34A to 34E, and each solenoid valve 15A to 15E opens to open each evaporator 1.
The supply of reduced pressure refrigerant to 2A to 12E is restarted, resulting in a so-called thermo-off, and a thermocycle consisting of thermo-on and thermo-off is repeated during the cooling operation. In addition, each low temperature case 1A
~1E, the load, that is, the quantity of products stored in the storage rooms 6A to 6E, is not constant, and the number of times the air curtain CA is disturbed depending on the number of times the product is taken out is also different, so the cycles of the thermocycles are different. .
According to FIG. 4, systems A and D are thermo-on, and systems B, C, and E are thermo-off.

When the cooling operation of each low-temperature case 1A to 1E has progressed for 3 hours, each control unit 28A to 28
A defrost signal is issued from E at the same time, and the first relay 3
All the electromagnetic coils 32A to 32E of 0A to 30E are excited, each contact piece 34A to 34E is closed, each electric heater 13A to 13E is energized, and the second
Electromagnetic coils 33A to 33 of relays 31A to 31E
E is de-energized, each contact piece 35A to 35E is opened, each electromagnetic valve 15A to 15E is closed, the supply of reduced pressure liquid refrigerant to each evaporator 12A to 12E is interrupted, and all evaporators are Defrosting of the containers 12A to 12E is started at the same time. Further, even after defrosting is started, the blower fan 10 that is constantly operated continues to operate, and the air whose temperature has been increased by each of the electric heaters 13A to 13E flows to each of the evaporators 12A to 12E. Due to the defrosting operation, the temperature in each of the storage compartments 6A to 6E rises little by little as in the conventional case. Furthermore, each of the solenoid valves 1
Each evaporator 12A-1 due to the closure of 5A-15E
The refrigerant in 2E is gradually pumped down, and when the low pressure becomes less than a predetermined value, a low pressure switch (not shown) is activated and the compressor 17 is stopped.

Each evaporator 1 by each electric heater 13A to 13E
The frost is gradually removed with heating from 2A to 12E,
Temperature sensors 27A to 27A indicate that the temperature of the air that has passed through each evaporator 12A to 12E has reached, for example, 5°C.
27E detects, the first relays 30A to 30E
The electromagnetic coils 32A to 32E are de-energized, the contact pieces 34A to 34E are opened, and the electric heaters 13A to 1
3E is de-energized, but since the amount of frost on the evaporators 12A-12E in each system A-E is different, the electric heaters 13A-13E are not de-energized at the same time but are de-energized individually, and are de-energized first. There is a time delay of several minutes between the electric heater that is energized and the last electric heater that is de-energized.

When each of the electric heaters 13A to 13E is de-energized, the timer of the control unit 28A to 28E counts the draining time of about 1 to 2 minutes, and then the second relay 31A to 31E is connected to each electric heater 13A to
Operate solenoid valve 1 in the order in which 13E becomes de-energized.
5A to 15E are opened sequentially. This solenoid valve 15A
When the low pressure force reaches a predetermined value with the opening of ~15E, the low pressure switch is activated, the compressor 17 is operated, and the refrigerant circulation is restarted, returning to the cooling operation, so-called thermocycle operation. In addition, even if the defrosting time is set to 20 minutes, the electric heater 1
The energization time to 3A to 13E is 15 minutes, and the water draining time is 2 minutes, making a total of 17 minutes, and the remaining 3 minutes are turned off.

According to the defrosting operation method for each of the low-temperature cases 1A to 1E described above, each of the low-temperature cases 1A to 1E
Since all of the evaporators 12A to 12E of the evaporator 1E start defrosting at the same time, even if cold air flows between the storage compartments 6A to 6E of the adjacent low-temperature case 1A to 1E, the The temperatures are approximately the same, so even if the amount of frost formed on each evaporator 12A to 12E is slightly different, defrosting can be completed in almost the same amount of time.

In addition, power is cut off to the defrost devices 12A to 12E of each evaporator individually for each evaporator, and the solenoid valve 15A corresponding to the defrost device whose power is cut off is cut off.
Since the evaporators are opened sequentially from 15E to 15E, it is not necessary to match the end of defrosting to the evaporator with the largest amount of frosting, and the evaporators that have completed defrosting first can be returned to cooling operation in order.

(g) Effects of the invention According to the present invention, the following effects are produced.

Because all of the evaporators in each low-temperature case start defrosting at the same time, even if cold air flows between the storage rooms in adjacent low-temperature cases, the temperature in each storage room remains approximately the same, and therefore each Even if the amount of frost on the evaporator is slightly different, defrosting can be completed in almost the same time, and as a result, the time required to defrost each low-temperature show case is shortened.

In order to cut off the power to the defrost device of each evaporator individually, and to sequentially open the solenoid valves corresponding to the defrost devices whose power was cut off, the end of defrosting is determined on the evaporator with a large amount of frost. The evaporator that finished defrosting first can be returned to cooling operation without the need to adjust the time, and as a result, the time from the end of defrosting to the start of cooling is shortened, allowing products with shortened time periods to be cooled quickly. This allows for better quality control of products.

[Brief explanation of the drawing]

The drawings are all related to the defrosting operation method for low-temperature show cases of the present invention, and FIG. 1 is a perspective view showing the connection of a plurality of low-temperature show cases, and FIG.
FIG. 3 is a refrigerant circuit diagram of the refrigeration system, and FIG. 4 is an electric circuit diagram. 1A~1E...Low temperature case, 6A~6E
...Storage room, 10...Cold air circulation path, 12A~12
E...Evaporator, 13A-13E...Electric heater (defrost device), 14...Blower fan, 15A-1
5E...Solenoid valve.

Claims (1)

[Claims] 1. An evaporator in which a solenoid valve is connected to the cold soot inlet side of the cold air circulation path of each low-temperature show case arranged in a straight line so that the storage chambers communicate with each other in the horizontal direction;
The evaporator is equipped with a defrosting device that melts the frost adhering to the evaporator during defrosting, and a blower fan that operates constantly.When defrosting starts, all the defrosting devices are energized and all solenoid valves are closed at the same time. A defrosting operation method for a low-temperature show case, in which, when defrosting is finished, power is cut off to the defrosting device of each evaporator individually for each evaporator, and solenoid valves corresponding to the defrosting devices whose power is cut off are sequentially opened.