JPH0366584B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a low-temperature show case in which a reversible blower fan and two evaporators are provided in a passage.

(b) Conventional technology JP-A-57-47176 (F25D21/06) and JP-A-58-178176 (F25D21/06) disclose a heat insulating technology in which an opening for storing and taking out products is formed on one side. A passage and a storage chamber are provided at both ends of the wall, and are disposed at an appropriate distance from the inner wall of the insulating wall, and are opposite to each other through the opening, and have vents at both ends, one of which serves as an outlet and the other serves as an inlet. A partition plate formed in the heat insulating wall, a reversible blowing fan supported by a fan case that bisects the passageway, and a fan case disposed between the fan case and both vents, one of which is A low-temperature show case is disclosed which is equipped with two evaporators, the other of which performs a defrosting operation during a cooling operation, and which defrosts the evaporator with a high-temperature refrigerant that has passed through a condenser when one of the evaporators is in a defrosting operation. ing.

(c) Problems to be Solved by the Invention In the above conventional technology, both evaporators that are operated for cooling alternately have an evaporator tube that evaporates the reduced pressure liquid refrigerant, and
Each evaporator is equipped with a defrosting pipe that allows high-temperature refrigerant to pass through, and while one evaporator is being defrosted, the defrosting pipe heats the entire evaporator, so the temperature of the air that has passed through the evaporator during defrosting is high. This creates a refrigeration load on the evaporator during cooling, causing the problem that the storage room does not drop to the specified temperature. There is also the problem that the temperature of the refrigerant increases significantly, and furthermore, when switching from cooling to defrosting, there is residual liquid refrigerant in the evaporator tube, which not only lengthens the defrosting time but also increases the evaporation during the cooling process. This also led to the problem of an acute shortage of refrigerant.

(d) Means for Solving the Problems In order to solve the above-mentioned problems, the present invention includes a heat insulating wall 3 having an opening 2 for storing and taking out products on one side thereof, and a heat insulating wall 3 having an opening 2 formed on one side for storing and taking out products, and a wall at an appropriate distance from the inner wall of the heat insulating wall. A passage 7 and a storage chamber 8 are formed in the heat insulating wall, and have ventilation ports 5 and 6 at both ends, which face each other through the opening, and when one is a blowout port, the other is a suction port. a partition plate 4 that divides the passage into two, and a fan 9 that is reversible in the forward and reverse directions and is supported by a fan case 10 that divides the passage into two.
and two evaporators 11A and 11B, each of which is disposed between the fan case and both of the vents, and one of which is in a cooling operation and the other is in a defrosting operation, and both of the vents 5 and 6. Two electric heaters 12A, 1 are respectively disposed in the passage 7 between the two evaporators 11A, 11B and are energized during defrosting operation of the corresponding evaporators.
2B and the passageway between the two evaporators, and when the air temperature in the passageway exceeds a predetermined temperature while either of the electric heaters is energized, the electric heaters 12A and 12B are A low-temperature case 1 comprising a temperature detector 21 that stops energization.
I will provide a.

(E) Effect For example, during the cooling operation of one evaporator 11B, the electric heater 12A that heats the other evaporator 11A,
The windward side of the evaporator 11A when viewed from the circulation direction of the airflow,
Since it is located on the leeward side of the vent 6 which serves as the suction port, it has almost no thermal influence on the cold air that forms a cold air curtain at the opening 2 out of the cold air that has been heat exchanged in the evaporator 11B. It is possible to defrost the evaporator 11A by heating the cold air that comes into contact with the outside air through the opening 2 and passes through the vent 6, and when defrosting the evaporator 11A, it is heated by the electric heater 12A. As the air flows from the upper end to the lower end of the evaporator 11A, its latent heat is gradually removed in order to thaw the frost. In addition, when the air temperature in the passage 7 reaches a predetermined temperature or higher due to the completion of defrosting of the evaporator 11A or a rise in outside air temperature, the temperature sensor 21 is forcibly activated regardless of the switching of the time switch (TS). Electricity is cut off to the electric heater 12A to prevent an increase in the refrigerating load on the evaporator 11B during the cooling operation. Furthermore, the solenoid valve 26A is closed during the cooling action of the evaporator 11B, and the evaporator 1 during defrosting is closed.
There is also an effect of gradually recovering 1A of residual liquid refrigerant.

(F) Embodiments Below, embodiments of the present invention will be described based on the drawings. 1 shown in FIG. 1 has a main body composed of a heat insulating wall 3 having an opening 2 for storing and taking out products on the upper surface thereof. In an open type low-temperature case, the insulation wall 3
Ventilation ports 5, which are arranged with metal partition plates 4 at appropriate intervals from the inner wall of the vents and face each other through the opening 2, and one of which serves as an air outlet and the other serves as an inlet; 6 at both ends, and a storage chamber 8 are formed. Reference numeral 9 denotes a reversible blower fan, and a fan case 1 divides the passage 7 into two, front and rear.
It is supported by 0. 11A and 11B are plate-fin type evaporators arranged between the vents 5 and 6 and the fan case 10, respectively, and facing the front wall 4A or the back wall 4B of the partition plate 4; an electric heater for defrosting, 13, disposed between the vents 5, 6 and both evaporators 11A, 11B, respectively;
14 is a honeycomb-shaped rectifier disposed in each of the vents 5 and 6; 15 is a partition plate provided on the back side of the evaporator 11A to form a space 16 between it and the front wall 4A of the partition plate 4; 17 is provided in the front of the evaporator 11B, and a space 18 is provided between the partition plate 4 and the back wall 4B.
A partition plate 19 is arranged in the storage chamber 8, and its front and rear ends are connected to the front and back walls 4A, 4B of the partition plate 4.
20 is a mirror disposed above the opening 2; 21 is a passage 7 located between the evaporators 11A and 11B, that is, near the blower fan 9;
This temperature sensor outputs a signal to a temperature switch, which will be described later, and opens when the air temperature in the passage is 5°C or higher, and closes when the air temperature is at a predetermined temperature of 5°C or lower. A machine room 22 is formed below the heat insulating wall 3, and houses a refrigerant compressor 23, a condenser 24, and a blower fan 25, which together with the evaporators 11A and 11B constitute a refrigeration system.

FIG. 2 shows the refrigerant circuit of the refrigeration system, in which the evaporator 11A is connected in series with a solenoid valve 26A and an expansion valve 27A, and the evaporator 11B is connected in series with a solenoid valve 26B and an expansion valve 27B, and they are connected in parallel with each other. . Furthermore, 2
8 is a liquid receiver, and 29 is a gas-liquid separator. The opening and closing operations of both the electromagnetic valves 26A and 26B are alternately switched by a timer.

Figures 3 and 4 show the electric circuit of the low-temperature case 1. Figure 3 shows the three-phase 200V power supply circuit, and the fourth
The figure shows a single-phase 100V power supply circuit. In FIG. 3, CM is a compressor motor connected to the R, S, and T phases via a tangent 52Ca of a compressor electromagnetic switch, which will be described later, and FM ₁ is the first auxiliary relay, which will be described later. The motor of the blower fan 25 is connected between the R and S phases via the tangent piece _1Xa1 , the thermostat TH for detecting the temperature of the storage chamber 8, the high/low pressure switch 63PH, and the second tangent piece of the first auxiliary relay. This is an electromagnetic switch for a compressor that is connected in series with 1Xa ₂ and between both R and T phases via two overload relays 0LR ₁ and 0LR ₂ . Also, in Fig. 4, SS is an operation switch, 1X,
2X, 3X are the first, second, and third auxiliary relays,
FM ₂ is a blower fan 9 with operating capacitor C
The CR surrounded by a chain line is a controller that houses an internal power supply ID, a delay switch LS, a temperature switch 21a, and a time switch TS. The time switch TS is opened and closed, for example, every two hours by a signal from a timer T in the controller CR, and this time switch has second and third auxiliary relays 2X and 3X connected in parallel to each other. are connected in series. 2Xa ₁ is the first contact piece of the second auxiliary relay 2X, and the solenoid valves 26A, 26 are provided in parallel with each other.
Contact one of the contacts b and a of each B. 2
Xa ₂ is the second node of the second auxiliary relay 2X, and the temperature switch 21 detects the air temperature in the passage 7.
The contact point c or d of each of the electric heaters 12A and 12B connected in parallel with each other is directly connected to the contact point c or d of the electric heaters 12A and 12B. 3Xa is the third auxiliary relay 3
The contact piece X is connected in series to the delay switch LS, and is also in contact with either the forward rotation contact e or the reverse rotation contact f of the motor FM ₂ of the blower fan 9. The delay switch LS is a delay timer in the controller CR.
It is opened and closed by signals from LT.
The delay timer LT is activated from the time when the time switch TS opens and closes, and the delay switch (LS) is activated after a time elapses, for example, 2, until the blower fan 9 completely stops when switching from forward rotation to reverse rotation or vice versa.
It closes.

Next, the operation of the low-temperature show case 1 will be explained based on FIGS. 1 to 4. When the operation switch SS is turned on, the first auxiliary relay 1X is energized and both the first and second contact pieces 1Xa ₁ and 1Xa ₂ is closed, which causes the compressor electromagnetic switch 52C to close.
When turned on, the contact piece 52Ca closes and the compressor 23 is driven. In this state, if the time switch is open, the second and third auxiliary relays 2
Since X and 3X are de-energized, the second auxiliary relay 2X has the first contact piece 2Xa ₁ as contact b and the second contact piece 2Xa ₂
is in contact with the contact d, and the contact piece 3Xa of the third auxiliary relay 3X is in contact with the reverse rotation contact f. As a result, the solenoid valve 26A
is energized and opened, hydraulic liquid refrigerant is supplied to the evaporator 11A, and the cooling action starts, but the temperature sensor 21
Since no close signal is output from the temperature switch 21a, the electric heater 12B is not energized. Then, two minutes after turning on the operation switch SS, the delay switch LS closes and the blower fan 9 is reversed, causing the evaporator 1
The cold air heat-exchanged at 1A is forcedly circulated as shown by the solid arrow in FIG. 1 to form a cold air curtain in the opening 2, thereby cooling the storage chamber 8. This is evaporator 11A
During this cooling operation, passage 7
When the internal air temperature reaches a predetermined temperature of 5° C. or lower, the temperature switch 21a closes and energizes the electric heater 12B to heat the returned cold air reaching the evaporator 11A.

Then, when two hours have passed since the operation switch SS was turned on, the timer T outputs an output and the timer switch TS is turned on.
At the same time, the delay timer LS is reset and the delay switch LS is opened. Then, the second and third
Both auxiliary relays 2X and 3X are energized, and the first,
Both second contact pieces 2Xa ₁ and 2Xa ₂ are in contact with the contacts b and c, respectively, and the contact piece 3Xa is in contact with the normal rotation contact e. Along with this switching operation, solenoid valve 2
6B is opened and reduced pressure liquid refrigerant is supplied to the evaporator 11B to start the cooling action, and at the same time, the electric heater 1
2A is energized. Then, two minutes after the switching operation, the delay timer LT outputs and the delay switch is activated.
Close the LS and rotate the blower fan 9 forward. As the blower fan 9 rotates forward, the cool air that has undergone heat exchange in the evaporator 11B is forcedly circulated as shown by the chain arrow in FIG.
While a cold air curtain is formed in the opening 2 to cool the storage chamber 8, the evaporator 11A is defrosted by being heated by the electric heater 12A to gradually melt the frost attached to the evaporator 11A.

From then on, this cooling operation was performed alternately every two hours.
For example, when one evaporator 11B is in a cooling operation, the other evaporator 11A is in a defrosting operation.

Therefore, according to such a configuration, for example, during cooling operation of one evaporator 11B, the electric heater 12A that heats the other evaporator 11A is placed on the upwind side of the evaporator 11A, as seen from the airflow circulation direction, at the suction port. Since it is on the leeward side of the vent 6, it has almost no direct thermal influence on the cold air that forms a cold air curtain on the opening 2 among the cold air heat-exchanged in the evaporator 11B. It is possible to defrost the evaporator 11A by heating the cold air that comes into contact with the outside air and passes through the vent 6, and when defrosting the evaporator 11A, the air heated by the electric heater 12A is During the flow from the upper end of the evaporator 11A to the lower end, the latent heat is gradually taken away to melt the frost, so the temperature after passing through the evaporator 11A does not rise until just before the end of defrosting of the evaporator 11A. , evaporator 11B
The temperature of the returned cold air can be lowered. As a result, it is possible to reduce the refrigerating capacity of the evaporator 11B, which is performing a cooling action, and to improve the defrosting efficiency of the evaporator 11A, which is performing a defrosting action. In addition, the air temperature in the passage 7 decreases to 5°C as the defrosting of the evaporator 11A ends or the outside air temperature rises.
When the above condition occurs, the power supply to the electric heater 12A can be forcibly cut off by the temperature switch 21a based on the open signal from the temperature detector 21, regardless of the switching of the time switch TS. An increase in the refrigeration load on the evaporator 11B can be prevented. Furthermore, since the solenoid valve 26A is closed during the cooling action of the evaporator 11B, and the residual liquid in the evaporator 11A during defrosting is also gradually recovered, a shortage of refrigerant in the evaporator 11B may occur. In addition to providing a stable cooling effect,
The rate of temperature increase in the evaporator 11A becomes faster than when there is liquid refrigerant, and the defrosting time of the evaporator 11A becomes faster. Furthermore, both evaporators 11A and 11B are connected to the partition plate 1.
A space 16, 1 is created between the partition plate 4 by 5, 17.
8, even during cooling or defrosting, heat is not directly transmitted from both to the partition plate 4, and as a result, the temperature in the entire storage chamber 8 can be maintained uniformly. I can do it.

(g) Effects of the invention According to the present invention described above, the effects listed below are produced.

The electric heater that heats the evaporator during defrosting is placed on the upwind side of the evaporator during defrosting when viewed from the direction of the circulating cold air.
Because it is located on the leeward side of the vent that serves as the suction port, it has almost no thermal effect on the cold air that has been heat exchanged by the evaporator during cooling and forms a cold air curtain at the opening. It is possible to heat the evaporator in frost, and since the air heated by the electric heater gradually loses its latent heat while passing through the evaporator during defrosting, the temperature does not rise much. Therefore, the temperature of the cold air returning to the evaporator during the cooling action can be kept low.
As a result, the refrigerating capacity of the evaporator can be reduced.

When the temperature inside the passage rises above a predetermined temperature due to the completion of defrosting the evaporator or a rise in outside air temperature, the electric heater is forcibly de-energized by the temperature sensor, so that the evaporation during the cooling operation is stopped. An increase in the refrigeration load on the container can be prevented.

Since the residual liquid refrigerant in the evaporator during defrosting can be recovered and used in the evaporator during cooling, it is possible to eliminate the refrigerant shortage in the evaporator during cooling, and also to reduce the rise of the evaporator during defrosting. It is possible to increase the heating rate and shorten the defrosting time.

[Brief explanation of drawings]

The drawings all show embodiments of the low-temperature show case of the present invention; FIG. 1 is a longitudinal sectional view, FIG. 2 is a refrigerant circuit diagram, and FIGS. 3 and 4 are electrical circuit diagrams. 2...Opening, 3...Insulating wall, 4...Dividing board,
5, 6...Vent, 7...Aisle, 8...Storage room,
9...Blower fan, 10...Fan case, 11
A, 11B... Evaporator, 12A, 12B... Electric heater, 21... Temperature detector.

Claims (1)

[Claims] 1. A heat insulating wall with an opening for storing and taking out products on one side, and walls arranged at an appropriate distance from the inner wall of the heat insulating wall, facing each other through the opening, and when one side is an outlet, the other is an outlet. a partition plate that forms a passage and a storage chamber in the heat insulating wall, each having a ventilation port serving as a suction port at both ends; a reversible ventilation fan supported by a fan case that bisects the passage; and the fan case. two evaporators respectively disposed between the two vent ports, one of which is in a cooling operation and the other in a defrosting operation; two electric heaters that are installed in the passageway between the two evaporators and are energized during the defrosting operation of the corresponding evaporators; A low-temperature case comprising a temperature detector that stops energizing an electric heater when the air temperature in a passage exceeds a predetermined temperature.