JPH01291084A - Low-temperature showcase - Google Patents

Abstract

PURPOSE:To restrain the temperature rise of an air curtain even during defrosting in either one of both evaporators, by a method wherein a passage is divided into two divisions of a high-pressure area and a low-pressure area while the high-pressure area is divided into an inside passage and an outside passage to branch air stream, passing through a second evaporator, into the inside passage and the outside passage at all times. CONSTITUTION:An air circulating passage 9 is divided into two parts of a high-pressure area and a low-pressure area by a fan case equipped with ventilating fans 8A, 8B. A second evaporator 14 is provided in the low-pressure area between the fan case and a suction port 11. A partitioning plate 12 between an inside passage 9A and an outside passage 9B, a first evaporator 13 arranged in the inside passage and a defrosting device 15 for frost adhered to the first evaporator 13 are provided in the high-pressure area between the fan case and blow-off ports 10A, 10B. Both of the evaporators are constituted so as to effect cooling operation and defrosting operation alternately. According to this method, cold air stream in the outside passage is blown off to form a low-temperature outer layer air curtain without being affected by the heat of the defrosting device and restrains the temperature rise of an inner layer air curtain as well as the invasion of atmosphere. A part of moisture in the cold air stream of the second evaporator upon off-cycle defrosting flows into the outside passage whereby the amount of frosting per unit time of the first evaporator during cooling may be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Industrial Application Field The present invention relates to an air circulation type low temperature showcase equipped with a plurality of evaporators.

(B) Prior Art Low-temperature showcases with a configuration in which two evaporators are arranged in one air circulation passage include the following A) and B).

A) Japanese Patent Publication No. 16914 (70818) Configuration for defrosting operation.

B) Japanese Patent Application Laid-Open No. 62-217080 (F25D211
As seen in 08), there is a ventilation fan in the passageway that can be rotated in forward and reverse directions, and 1. A configuration in which both the second evaporator and the second evaporator are arranged, the two evaporators are operated alternately for cooling and defrosting, and the blower fan is rotated forward and backward.

(8) Problems to be Solved by the Invention In A) above, in order for all of the high humidity air that has passed through the second evaporator during defrosting to pass through the first evaporator during cooling, If the amount of frost on the evaporator increases rapidly, the heat exchange of the first evaporator becomes poor, and if the second evaporator is heated with an electric heater for defrosting, all of the air heated by this electric heater becomes Due to the refrigeration load on the first evaporator during cooling, the temperature of the air curtain is higher than when only the first evaporator is cooled, and the temperature in the storage room increases significantly in the latter stages of defrosting the second evaporator. A problem arose.

In addition, in B) above, in addition to the same problem as A) above, when switching the fan between forward and reverse rotation, the air curtain must be completely stopped to avoid locking the motor. During this period, a large amount of outside air enters the storage room, causing a problem in that the temperature of the storage room increases significantly.

The present invention aims to solve the above-mentioned problems. The temperature rise of the air curtain is suppressed even during defrosting of both the second evaporators.

(d) Means for Solving the Problems In order to solve the above problems, the present invention includes a blower fan arranged in the air circulation passage so as to divide the passage into a high pressure area and a low pressure area. a second evaporator disposed in a low pressure area between the fan case and the suction port, and a partition plate that partitions the high pressure area between the fan case and the air outlet into an inner path and an outer path. a first evaporator disposed in the inner path; and a defrosting device for removing frost attached to the first evaporator. Both second evaporators were configured to perform cooling and defrosting operations alternately.

(n) Divide the working passage into two areas, a high pressure area and a low pressure area, using a fan case.
Furthermore, the high-pressure area is divided into an inner path and an outer path, so that the airflow that has passed through the second evaporator can be divided into the inner path and the outer path at all times. The cold air flow whose temperature has been lowered through heat exchange in the evaporator is divided into an inner path and an outer path, and among these divided cold air flows, the cold air flow that flows into the inner path heats the first evaporator. The temperature gradually rises under the influence of the heat of the device and is blown out as an inner layer air curtain through the opening, but the cold air flowing through the outer path is not affected by the heat of the defrosting device and is blown out into the opening at a lower temperature. It is formed as an outer layer air curtain, and during off-cycle defrosting of the second evaporator, part of the cold air flow that has passed through the second evaporator passes through the first evaporator that is being cooled from the inner passage, and the other part passes through the first evaporator that is being cooled. Since the flow is diverted to pass through the outer path, the amount of frost formed in the first evaporator per unit time is reduced.

(f) Example The present invention will be described in detail below with reference to the drawings.

Figure 1 (1) shows an opening (3) on the top surface for storing and taking out products.
This is a low-temperature showcase whose main body is composed of a heat insulating wall (2) formed with a heat insulating wall (2), and a storage chamber (6 )
and a fan case (7) disposed in the bottom area and both first and second blower fans (8) supported by the fan case.
A) A passageway (9) for airflow circulation comprising (8B) is formed. The passageway (9) has one end connected to the first. 2nd Suita Exit (
IOA) (IOB> is provided along the rear edge of the opening (3), and the other end is provided as a suction port (11) along the front edge of the opening (3). Mouth (IO
One of A) (IOB) blows out a cold air flow shown by a solid line arrow, and the other blows a protective air flow shown by a chain line arrow toward the opening (3), and is formed by arranging a partition plate to be described later. (12) is the fan case (7) and the first. This partition plate (12
), an inner path (9A) in which the first evaporator (13) is disposed and through which the cold air flow passes, and an outer path (9B) through which the protective air flow passes are formed. (14) is a second evaporator disposed in the passage (9) between the fan case (7> and the suction port (11)). (15) is the air of the first evaporator (13). A defrosting device such as an electric heater placed on the inlet side is energized when defrosting the first evaporator (13).

The fan case (7> functions to partition the passage (9>) into a high pressure area and a low pressure area, and both the first and second blower fans (8A
) The first evaporator (
13) is arranged, and a second evaporator (14) is arranged in the low pressure area on the windward side. As shown in FIGS. 2 and 3, the fan case (7) has first blowing fans (8A) for circulating cold air on both left and right sides, and a second blowing fan (8A) for circulating protective air in the center.
In addition to being equipped with a blower fan (8B), a second blower fan (8B) is also provided.
) leads the airflow from the auxiliary duct (16
).

Figure 4 shows the refrigerant circuit of the low temperature showcase (1).
20) is a refrigerant compressor, (21) is a refrigerant condenser, (22)
(23) is the first. Both second solenoid valves (25) and (26) are pressure reducing devices such as expansion valves, and the first and second solenoid valves (25) and (26) are pressure reducing devices such as expansion valves. Second double evaporator (13)
(14) are mutually parallel and corresponding to the first . It is connected in series with both second solenoid valves (22) (23) and pressure reducing devices (25) (26). The second solenoid valve (23) is opened and closed based on a signal from a defrost timer, which will be described later, and the first solenoid valve (22) is opened and closed based on signals from the temperature switch and the defrost timer. . In addition, 1st. When at least one of the second solenoid valves (22) and (23) is closed, the corresponding first solenoid valve (22) and (23) are closed. Both evaporators (13) (14)
) A pump-down operation is performed to recover the residual liquid refrigerant in the condenser (21), and during the pump-down operation when both solenoid valves (22) and (23) are closed, a low pressure and force are maintained at a predetermined level. When the pressure drops to this level, the compressor (20) is stopped by a low pressure switch (not shown).

Figure 5 shows the electric circuit of 1φ100■, Figure 6 shows the electric circuit of 1φ200
The electric circuit of v is shown.

In Fig. 5, (DT) is a defrost timer consisting of, for example, a 24-hour cycle timer, and its contact (DT,) is used when the store is open, when the opening time is 3 hours, the closing time is 30 minutes, and when the store is closed. During business hours, the opening time is set to 4 hours and the closing time is 1 hour. A first auxiliary relay (IX) is connected in series to the contact piece (DT, ). (TH) is a temperature switch such as a thermostat, which constitutes a series circuit with the first solenoid valve (22), the normally closed contact (tX, ) of the first auxiliary relay (1x), and the contact piece (IXI). There is. The normally closed contact (txb) and contact piece (IXI) have a second
Auxiliary relay normally closed contact (2XJ and first contact (2X1)
series circuits are connected in parallel.

(IX,) is the normally open contact of the first auxiliary relay (1x), and this contact (IX,) includes the normally closed contact (txb), the temperature switch (TH), and the first solenoid valve (22). A second solenoid valve (23) and an overheat protector (27) which are in a parallel relationship are connected in series. Further, a second auxiliary relay (2X) is connected in parallel to the second solenoid valve (23). Further, the first and second blower fans (8A) (8B) are connected to the defrost timer (DT) via the operating capacitors (C1) (C1).
are connected in parallel. Note that (2X,) is a normally open contact that is in a parallel relationship with the normally closed contact (zxb). The temperature switch (I) controls the opening and closing of the first electromagnetic valve (22) by repeating the opening and closing operation, for example, at -4°C and at 0°C, at regular intervals, and the temperature switch (I) controls the opening and closing of the first electromagnetic valve (22). 6) Maintain the temperature at approximately -2°C, which is considered to be in the freezing temperature range. Further, the overheat protector (27) opens at 5°C and closes at 0°C.

In FIG. 6, (2X2) is the second auxiliary relay (2
The second contact piece of X) is connected in series with the defrosting device (15).

Next, the operation of the low temperature grain case (1) will be explained.

First, when the contact (DI',) of the defrost timer (DT>) is open, the first auxiliary relay (1x) is de-energized and its contact (IXI) is in contact with the normally closed contact (LX,). and
The second auxiliary relay (2x) is also de-energized, and its first contact (
2X 1 ) is in contact with the normally closed contact (zxb) and -C, so the first solenoid valve (22) is energized through the temperature switch (TI), so the first evaporator (13) is depressurized. It performs cooling action by receiving liquid refrigerant supply. At this time, the second electromagnetic valve (23) is de-energized and closed, and the reduced pressure liquid refrigerant is not supplied to the second evaporator (14).

Therefore, when cooling the first evaporator (13), only the cold air flow passing through the inner passage (9A) among the circulating air flows indicated by the solid line and the dashed line double arrows in FIG. Due to heat exchange, the inner air curtain (CA) formed by the cold air flow is maintained at, for example, -6°C, and the outer air curtain (GA) formed by the protective air flow is maintained at 4°C.

Next, when the defrost signal is output from the defrost timer (DI) and its contact (D?,) closes, the first auxiliary relay (IX)
is excited and its contact (IXI) becomes a normally closed contact (ix, )
The switch switches from to the normally open contact (IX, ), and the second solenoid valve (2
3) is energized and opened, while the second auxiliary relay (2X) is energized. As the second auxiliary relay (2x) is energized, the first contact (2X1) switches from a normally closed contact (2X, ) to a normally open contact (2X, ), and the second contact (2X2
) is closed, and with this operation, the supply of reduced pressure liquid refrigerant to the first evaporator (13) is stopped, and the defrosting device (15) is closed.
), the first evaporator (13) is heated, and at the same time, the reduced pressure liquid refrigerant is supplied to the second evaporator (14).

Therefore, when the first evaporator (13) is defrosted and the second evaporator (14) is cooled, part of the cold air flow heat exchanged in the second evaporator (14) is transferred to the inner path (9A ), passes through the first evaporator (13), and is blown out to the opening (3) as an inner air curtain (CA), while the other part is an outer channel (9B).
and is blown out to the opening (3) as an outer layer air curtain (GA). At this time, the temperature of the cold air flow immediately after passing through the second evaporator (14) is -6°C, but the temperature of the cold air flow divided into the inner path (9A) gradually rises with the passage of time, and the temperature of the cold air flow is 16°C. The cold air flow that is divided into the side channel (9B) and becomes the protective air flow is 16.
Form an outer layer air curtain (GA) at a temperature of °C.

Defrosting of the first evaporator (13) progresses and the first evaporator (13)
) When the temperature of the cold air flow that has passed through reaches, for example, 5°C and the overheat protector (27) opens, or when the contact piece (DT, ) of the defrost timer (DT) opens, the second solenoid valve (23) is de-energized and closed, the second auxiliary relay (2x) is de-energized, and the first contact piece (2X1) changes from the normally open contact (2X, ) to the normally closed contact (
2Xb), the second contact (2X2) opens, or the first auxiliary relay (1x) becomes de-energized and the contact (LXl) changes from the normally open contact <LX, ) to the normally closed contact (IL )
Switch to . With this operation, defrosting of the second evaporator (14) is completed, and cooling of the first evaporator (13>) is restarted.

The frost attached to the second evaporator (14) is removed from the first evaporator (13).
), it is gradually removed by the return cold air flow above 0°C returning from the suction port (11). At this time, the high-humidity cold air flow that has passed through the second evaporator (14) during defrosting is divided into the inner path (9A) and the outer path (9B), so that
The amount of frost formed on the first evaporator (13) per unit time during cooling is reduced.

(g) Effects of the invention The present invention described above produces the following effects.

■The cold air flowing through the outer path is blown out through the opening without being affected by the heat of the defrosting device, forming a low-temperature outer layer air curtain, so the outer layer air curtain can suppress the temperature rise of the inner layer air curtain. At the same time, it is possible to suppress the entry of outside air into the storage room, and as a result, it is possible to suppress the temperature rise in the storage room.

■Some of the moisture contained in the cold airflow that has passed through the second evaporator, which is being defrosted in the off-cycle, will flow to the outer path, resulting in a reduction in the amount of heat exchanged airflow in the first evaporator that is being cooled. There will be less moisture and better heat exchange in the first evaporator.

[Brief explanation of the drawing]

The drawings all show embodiments of the present invention, and FIG. 1 is a longitudinal cross-sectional view of a low-temperature showcase, FIG. 2 is a perspective view of the same essential parts, FIG. 3 is a perspective view of a fan case, and FIG. 4 is a refrigerant circuit. Figure, Figure 5,
FIG. 6 is an electrical circuit diagram. (6)...Storage room, (7)...Fan case,
(8A) (8B)...Blower fan, (9)...Passway, (9A)...Inside path, (9B)...Outside path, (IOA>(IOB)...Blower outlet, (11)...
・Suction port, (12)...Partition plate, (13) (14)
)...Evaporator, (15)...Defrosting device. Figure 4 gJ3

Claims (1)

[Claims] 1. In a low-temperature showcase of an airflow circulation type in which an air curtain is formed by blowing air from an air outlet along one edge of an opening for storing and taking out products to an air inlet along the other edge of the opening, the airflow A fan case disposed in the circulation passage so as to divide the passage into a high pressure area and a low pressure area and provided with a blower fan, and a second fan case disposed in the low pressure area between the fan case and the suction port. an evaporator, a partition plate that partitions a high-pressure area between the fan case and the outlet into an inner path and an outer path, a first evaporator disposed in the inner path, and a partition plate attached to the first evaporator. A low-temperature showcase comprising a defrosting device for removing frost, and in which both the first and second evaporators are alternately operated for cooling and defrosting.