JP7229670B2 - Frozen/refrigerated showcase - Google Patents

Description

The present invention relates to a freezer/refrigerated showcase.

2. Description of the Related Art Supermarkets, convenience stores and the like are equipped with freezer/refrigerated showcases for displaying articles such as frozen foods and perishable foods while being frozen or refrigerated. A freezer/refrigerated showcase has a ventilation passage formed between an outer box and an inner box that constitute the case body, and an evaporator, which is a part of the refrigeration cycle, is provided in the ventilation passage together with a blower. there is The evaporator draws heat from the air around the evaporator by the heat of vaporization when the refrigerant flowing into the evaporator evaporates. It freezes or refrigerates the items that are sent inside and displayed in the warehouse.

In such a freezer/refrigerated showcase, the continued cooling operation of the evaporator causes frost to form on the evaporator. For example, there is known a freezer/refrigerator showcase having a defrosting operation that defrosts frost that has formed by heating an evaporator.

For example, the freezer/refrigerated showcase shown in Patent Document 1 heats a heater disposed below a cooler (evaporator) and melts all the frost that has formed to defrost the cooler. The cooling capacity of the cooler is maintained by performing a so-called heating-type defrosting operation.

Also, in such a freezer/refrigerated showcase, a night cover is used to prevent outside air from flowing into the refrigerator at night or during non-business hours when articles are not put in or taken out, and the cooler is operated at a low output. ing.

Japanese Utility Model Publication No. 7-12861 (page 2, Fig. 1)

However, in the freezer/refrigerated showcase of Patent Document 1, although the cooling capacity of the cooler can be maintained by performing the defrosting operation at appropriate intervals, for example, when the business hours are long, the business hours Defrosting operation may be performed during freezing, and the temperature inside the refrigerator rises sharply by using a heater with a large amount of heat to completely melt and defrost the frost that has formed on the cooler. Alternatively, since the temperature of the refrigerated goods also rises, there is a risk that the goods will be damaged without being sufficiently cooled.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a freezer/refrigerator showcase capable of keeping articles cold for a long time in a substantially constant temperature range.

In order to solve the above problems, the freezer/refrigerated showcase of the present invention includes:
A freezer/refrigerator showcase that performs a cooling operation to cool the inside of the refrigerator during the defrosting operation of the evaporator,
A solenoid valve is connected to the downstream side of the evaporator,
The cooling operation is performed in a lower temperature range and in a shorter time than the normal cooling pattern for cooling the evaporator and the defrosting operation, and closes the electromagnetic valve to increase the pressure inside the evaporator. and a frost formation suppression cooling pattern that raises the temperature of
In the frost suppression cooling pattern, when the temperature of the evaporator reaches a predetermined temperature of 0 degrees or less and near 0 degrees, the time is measured by the time measuring means, and the measured time becomes the predetermined time. It is characterized in that the frost formation suppression cooling pattern is occasionally switched to the normal cooling pattern.
According to this feature, by alternately performing the normal cooling pattern and the frost formation suppression cooling pattern, it is possible to reduce the amount of frost that forms on the evaporator while suppressing the temperature rise in the refrigerator. interval can be lengthened. Thereby, the article can be kept cold for a long time in a substantially constant temperature zone lower than the temperature zone in the defrosting operation.

The evaporator is characterized in that the pressure inside the evaporator is increased in the frost suppression cooling pattern.
According to this feature, since the temperature of the evaporator can be raised by increasing the pressure inside the evaporator, it is possible to easily control the temperature of the evaporator and raise the temperature of the frosted portion from the inside of the evaporator. By doing so, the frost can be easily dropped without melting the whole, so the efficiency of frost formation suppression is good.

A solenoid valve is connected to the downstream side of the evaporator.
According to this feature, closing the electromagnetic valve increases the pressure in the evaporator and raises the temperature of the evaporator, thereby facilitating temperature control of the evaporator.

The evaporator includes a temperature sensor that detects the temperature of the evaporator in the frost suppression cooling pattern, a time measuring means that measures the time during which the temperature detected by the temperature sensor is in the low temperature range for a predetermined time, and is used to switch from the frost formation suppression cooling pattern to the normal cooling pattern.
According to this feature, in the anti-frost cooling pattern, when the time during which the evaporator is in the low temperature zone is measured for a predetermined time, the anti-frost cooling pattern is switched to the normal cooling pattern. Hard to get up.

The time measuring means is characterized in that it starts measuring the predetermined time from a predetermined temperature within a range of -2°C to 0°C.
According to this feature, the temperature of the evaporator is kept near 0 degrees to suppress frost formation, while preventing an excessive temperature rise in the refrigerator.

The frost formation suppression cooling pattern is characterized in that it is performed at predetermined intervals in the cooling operation.
According to this feature, the amount of frost forming can be suppressed over a long period of time.

1 is a sectional view showing the structure of a freezer/refrigerator showcase in an embodiment of the present invention; FIG. It is a block diagram showing the structure of the piping system of the refrigeration cycle. It is a schematic diagram which shows the structure of an evaporator. FIG. 4 is a block diagram showing the configuration of an evaporator, upstream and downstream electromagnetic valves in a normal cooling pattern; FIG. 4 is a block diagram showing the configuration of the evaporator and the upstream and downstream solenoid valves in the frost suppression cooling pattern or defrosting operation; FIG. 4 is a block diagram showing the configuration of an evaporator, upstream and downstream solenoid valves in a defrosting operation; It is a graph which shows article temperature, internal temperature, outlet temperature, and surface temperature of an evaporator. 4 is a graph showing the article temperature, the inside temperature, the outlet temperature, and the evaporator surface temperature in the frost formation suppression cooling pattern. (a) is a table showing changes in the surface temperature of the evaporator and heat transfer tubes, the operation of each solenoid valve, the operation of each thermostat, and each timer control in the frost formation suppression pattern, and (b) is a defrosting operation. 1 is a table showing changes in the surface temperature of the evaporator and heat transfer tubes, the operation of each solenoid valve, the operation of each thermostat, and the transition of each timer control. (a) is a cross-sectional view showing a frost column formation period on the heat transfer tube, (b) is a cross-sectional view showing a frost layer growth period on the heat transfer tube, and (c) is a frost layer on the heat transfer tube. It is a sectional view showing a mature stage.

A mode for carrying out a freezer/refrigerated showcase according to the present invention will be described below based on an embodiment.

A freeze/refrigerate showcase according to an embodiment will be described with reference to FIGS. 1 to 10. FIG. Hereinafter, the left side of the paper surface of FIG. 1 is defined as the front side (front side) of the freezer/refrigerated showcase, and the description will be made based on the vertical and horizontal directions when viewed from the front side.

As shown in FIG. 1, a freezer/refrigerated showcase 1 is mainly installed in shops, supermarkets, convenience stores, and other stores that handle products (goods) such as foods, and keeps products cold while keeping them cold. Alternatively, it is installed to display in a frozen state, and in a cold storage chamber 5 (inside) surrounded by an inner box 3 with an open front side, shelves 6, 6, . . . A plurality of boxes are installed in the vertical direction, and commodities can also be displayed on the bottom part 3b provided at the bottom of the inner box 3. - 特許庁In addition, the frozen/refrigerated showcase 1 of the present embodiment will be described by exemplifying a mode in which the products are displayed in a refrigerated state.

The freezer/refrigerated showcase 1 includes an outer box 2 having a substantially U-shaped heat-insulating structure with an open front (left side in the figure) and an inner box 3 inside of which has a substantially U-shaped open front. The internal space of the case body is a cold insulation chamber 5. Rear ends of brackets 28, 28, . . Merchandise is displayed on the upper surfaces of the shelves 6, 6, . . . and the bottom portion 3b of the inner box 3.

A ventilation passage 7 is formed between the outer casing 2 and the inner casing 3, and an evaporator 8 and a blower 9 are installed in the vertical portion and the horizontal bottom portion of the ventilation passage 7, respectively. As will be described later, the evaporator 8 can cool the air around it. A heat insulating material 29 is provided on the front side of the evaporator 8 to suppress heat exchange between the evaporator 8 and the cold insulation chamber 5 through the inner box 3 . A cold air outlet 10 communicating with the ventilation passage 7 is formed downward at the front end of the upper part of the case body, and a cold air suction port 11 opening upward is formed at the upper end of the lower front end of the case body.

The evaporator 8 is set so that the cooling set temperature (outlet temperature) during normal operation (during business hours) is around -2.5 degrees. It is around 0.0 degrees, and the article temperature is around 2.0 degrees (see FIG. 7). Note that the inside temperature here refers to the temperature near the shelves 6, 6, . . . It can be changed by operating the control unit that does not. Also, the article temperature here refers to the average temperature of each article displayed on the shelves 6, 6, . . . and the bottom 3b. Further, each temperature described in the present embodiment is not limited, and may be changed as appropriate, and the same applies to other numerical values.

When the blower 9 is operated, the cold air cooled by the evaporator 8 flows upward in the ventilation passage 7 as indicated by the arrow, and is blown downward from the cold air outlet 10 toward the suction port 11. (Hereinafter, the air (cold air) circulated in this way is simply referred to as “circulating air”). As a result, an air curtain 12 of cool air is formed on the open face of the front surface of the case body, and part of the cool air flows into the cold insulation chamber 5, thereby keeping the displayed commodities cool.

Next, the evaporator 8 in the freezer/refrigerator showcase 1 will be described. As shown in FIG. 3, the evaporator 8 includes a heat transfer tube 15, which is a copper tube through which a refrigerant 16 flows. It extends like As a result, the contact area between the heat transfer tubes 15 and the surrounding air increases, and the air blown from the blower 9 hits them efficiently, improving the cooling efficiency. The heat transfer tube 15 is not limited to a copper tube, and may be a metal or resin tube having high thermal conductivity.

The heat transfer tube 15 includes a plurality of straight pipe portions 15a, 15a, . . . passing through a plurality of fins 30, 30, . It is composed of connecting U-bend portions 15b, 15b, . . . and is easy to assemble.

Structurally, the heat transfer tube 15 has the U bend portions 15b, 15b, . Frost forms on the bend portions 15b, 15b, . . . more easily than on the straight pipe portions 15a, 15a, .

Among the U-bend portions 15b, 15b, . The frost formation is the greatest because it comes into contact with the A straight pipe portion 15a' connected to the upstream side of the U-bend portion 15b' is provided with a first temperature sensor H1 on the upstream side and a second temperature sensor H2 on the downstream side.

Detection signals (surface temperatures of the heat transfer tubes 15) detected by the first temperature sensor H1 and the second temperature sensor H2 are input to a control unit (not shown). The controller compares the detection signal with a preset temperature and outputs ON/OFF signals from thermostats T1 to T4 (thermostats T1 and T3 are connected to the first temperature sensor H1, and thermostats T2 and T4 are connected to the second temperature sensor H2). ) (see FIG. 9) and functions of timers M1 to M5 (time measuring means) for measuring each set predetermined time. The controller is also connected to a first electromagnetic valve S1 and a second electromagnetic valve S2, which will be described later, and controls opening and closing of these valves. Furthermore, the controller is connected to a plurality of temperature sensors (not shown) provided near the shelves 6, 6, . . . temperature and the temperature of the air that has passed through the evaporator 8) are input.

In this embodiment, the first temperature sensor H1 and the second temperature sensor H2 measure the surface temperature upstream and downstream of the straight pipe portion 15a′ of the heat transfer tube 15. The surface temperature of other parts may be measured by one or three or more temperature sensors. In addition, each temperature sensor measures the surface temperature of the heat transfer tube 15, the temperature of the air that has passed through the evaporator 8, the temperature inside the refrigerator, and the temperature of the article. It suffices if it is provided at a position where it can measure at least one of the temperature of the air that has passed through the vessel 8, the internal temperature of the refrigerator, and the temperature of the article.

As shown in FIG. 2, the evaporator 8 is part of the piping system F of the refrigeration cycle. More specifically, an expansion valve 17 is provided at the upstream end of the heat transfer tube 15 of the evaporator 8 to reduce the pressure of the liquefied refrigerant 16 to a predetermined evaporation pressure to vaporize the refrigerant. A supply pipe 19 provided with a second solenoid valve S2 is connected to the upstream side of the expansion valve 17, and a liquid receiver 18 is connected via the supply pipe 19 to the upstream side of the second solenoid valve S2. . The second electromagnetic valve S2 can appropriately open and close the channel of the supply pipe 19 between the expansion valve 17 and the receiver 18 .

A lead-out pipe 23 provided with a first electromagnetic valve S1 is connected to the downstream end of the heat transfer pipe 15 of the evaporator 8. A compressor 21 (pump) is connected to suck the vaporized refrigerant 16, compress the refrigerant 16, and send the refrigerant 16 to the liquid receiver 18 side. connected to the device 18 . The condenser 22 releases the heat of the refrigerant 16 compressed by the compressor 21 in a high-pressure vaporized state to the outside to liquefy the refrigerant 16 .

In FIG. 2, the refrigerant 16 in a liquid (liquefied) state is indicated by a solid line, and the refrigerant 16 in a gaseous (vaporized) state is indicated by a broken line. The temperature of the liquefied refrigerant 16 in the liquid receiver 18 is, for example, about 35 to 40 degrees in summer and about 20 degrees in winter.

As shown in FIGS. 2 and 4 to 6, the first solenoid valve S1 connects the heat transfer tube 15 and the lead-out tube 23 (see FIG. 4), and shuts off the heat transfer tube 15 and the lead-out tube 23. (See FIGS. 5 and 6). In addition, the second electromagnetic valve S2 has a mode in which the supply pipe 19 and the heat transfer pipe 15 are communicated (see FIGS. 4 and 5), a mode in which the supply pipe 19 and the heat transfer pipe 15 are blocked (see FIG. 6), It is possible to switch to

In addition, the first solenoid valve S1 is a so-called normally open valve that is closed when energized and open when de-energized. state, and the refrigerant 16 can be prevented from remaining in the evaporator 8 . As a result, it is possible to prevent the occurrence of the liquid backflow phenomenon when the operation is restarted. A check valve may be arranged between the first solenoid valve S1 and the compressor 21 in order to prevent the liquid back phenomenon from occurring.

As shown in FIGS. 7 and 9, the freezer/refrigerator showcase 1 in this embodiment performs a defrosting operation D for defrosting the evaporator 8 at set time intervals (12 hours). , between the defrosting operation D and the next defrosting operation D, a cooling operation C for cooling the cold storage chamber 5 is performed. In this cooling operation C, the normal cooling pattern P1 and the frost formation suppression cooling pattern P2 are repeatedly performed. Next, the operation modes of the piping system F of the refrigeration cycle in the normal cooling pattern P1, the frost suppression cooling pattern P2, and the defrosting operation D will be individually described with reference to FIGS. 4 to 10. FIG. It should be noted that the suppression of frost formation (suppression of frost formation) in this embodiment includes not increasing frost, reducing frost, and completely removing frost.

First, the operation mode of the piping system F of the refrigeration cycle in the normal cooling pattern P1 of the cooling operation C will be described. As shown in FIGS. 2 and 4, the first electromagnetic valve S1 and the second electromagnetic valve S2 are in an open state, and the heat transfer tube 15 and the lead-out tube 23, and the heat transfer tube 15 and the supply tube 19, respectively. are communicated. By the operation of the compressor 21 , the liquefied refrigerant 16 stored in the liquid receiver 18 is sent out toward the evaporator 8 via the supply pipe 19 and the expansion valve 17 . The refrigerant 16 in the liquefied state is decompressed by the expansion valve 17 so as to have a predetermined evaporation pressure, and becomes vaporized. The vaporized refrigerant 16 that has flowed into the heat transfer tubes 15 of the evaporator 8 takes heat from the air in the air passage 7 , thereby cooling the air in the air passage 7 .

In addition, in the normal cooling pattern P1, in order to keep the inside temperature substantially constant, the control unit controls ( The cooling capacity of the evaporator 8 can be controlled by repeatedly supplying and stopping the refrigerant 16 into the evaporator 8 by opening and closing the second solenoid valve S2 by, for example, PWM control.

The vaporized refrigerant 16 that has passed through the heat transfer tube 15 of the evaporator 8 flows into the outlet tube 23 communicating with the heat transfer tube 15 and is returned to the liquid receiver 18 via the compressor 21 and the condenser 22 . By repeating this circulation, the normal cooling pattern P1 of the evaporator 8 is continuously continued. When the evaporator 8 is in the normal cooling pattern P1, the surface temperature of the heat transfer tube 15 is around -9 degrees due to the vaporized refrigerant 16 flowing into the heat transfer tube 15 (see FIG. 7). Further, as described above, the inside temperature is around 0.0 degrees, and the article temperature is around 2.0 degrees (see FIG. 7).

The normal cooling pattern P1 is controlled so as to always be performed before the frost formation suppression cooling pattern P2 or the defrosting operation D, and the frost formation suppression cooling pattern P2 or the frost formation suppression cooling pattern P2 or Since the defrosting operation D is performed, it is possible to prevent an excessive rise in the internal temperature.

Here, the amount of frost formed on the heat transfer tubes 15 according to the elapsed time of the normal cooling pattern P1 will be described. As shown in FIG. 10(a), when the normal cooling pattern P1 is started, water droplets formed by condensing moisture in the air adhere to the outer surface of the heat transfer tube 15, and frost columns 33, 33, . . . frost column). Next, as shown in FIG. 10(b), ice/air mixtures 34, 34, . . . are generated around the frost columns 33, 33, . Then, as shown in FIG. 10(c), the ice/air mixture 34, 34, . It becomes an integral frost layer (frost layer maturity period). When this frost layer maturity period is reached, the cooling capacity of the evaporator 8 is significantly reduced, so it is necessary to perform a defrosting operation (heating method, off-cycle method, defrosting operation D in this embodiment, etc., which will be described later). There is

Next, the operation mode of the piping system F of the refrigeration cycle in the frost formation suppression cooling pattern P2 will be described. It should be noted that the description of the evaporator 8 overlapping with the description of the operation mode of the piping system F of the refrigeration cycle in the normal cooling pattern P1 will be omitted.

As shown in FIGS. 8 and 9A, when the time measured by the timer M2 reaches 50 minutes after the start of the normal cooling pattern P1, the first solenoid valve S1 is closed, and the frost suppression cooling pattern P1 is started. The temperature rise process α1 of P2 is started. As a result, the refrigerant 16 stays in the evaporator 8, and the subsequent refrigerant 16 sent out by the operation of the compressor 21 continues to flow into the evaporator 8 (see FIG. 5), so that the first electromagnetic valve S1 is closed. Immediately after the operation, the pressure of the refrigerant 16 in the evaporator 8 rises sharply, and the temperature of the heat transfer tubes 15 rises rapidly (see FIG. 8).

In response to the fact that the temperatures individually measured by the first temperature sensor H1 and the second temperature sensor H2 (the surface temperature of the heat transfer tube 15) both reached -1 degrees (predetermined temperature) (see FIG. 8), the thermostat T1 , T2 are both activated (ON), time measurement by the timer M1 is started, and the temperature constant process α2 is started. In the temperature constant process α2, the first solenoid valve S1 is closed and the second solenoid valve S2 is opened in the same manner as in the temperature rise process α1, but they are distinguished for convenience of explanation.

In the temperature constant process α2, if the temperatures individually measured by the first temperature sensor H1 and the second temperature sensor H2 are both −1° C. or higher, the timer M1 continues to measure the time, and the time when the temperature is −1° C. or higher. After reaching 4 minutes (predetermined time), the controller opens the first solenoid valve S1 and shifts to the normal cooling pattern P1. As a result, the refrigerant 16 can pass through the evaporator 8, and the refrigerant 16 flows into the compressor 21 from the evaporator 8, which was in a high pressure state. Since the P1 normal pressure is quickly restored and the cooling of the evaporator 8 is immediately started, the influence on the inside temperature and the article temperature can be suppressed.

On the other hand, when either the temperature measured individually by the first temperature sensor H1 or the second temperature sensor H2 falls below -1°C in the constant temperature process α2, the timer M1 is reset, and then the process returns to the temperature increasing process α1. , in the next constant temperature process α2, time is measured again from 0 by the timer M1.

In this way, in the constant temperature process α2, the surface temperature of the heat transfer tube 15 is maintained at −1° C. or higher, which is close to the melting point of ice (0° C.), continuously for 4 minutes. The portion where the heat transfer tube 15 is exposed is heated directly from the inside of the heat transfer tube 15 and is likely to be melted. In addition, since the surface temperature of the heat transfer tube 15 is −1° C. or higher, it is difficult for new frost to form. That is, in the temperature constant process α2, the surface temperature of the heat transfer tube 15 is generally below 0 degrees for 4 minutes, and it is difficult to reach 0 degrees or more, and frost formation is suppressed while preventing the temperature inside the refrigerator from rising. .

In addition, since the frost suppression cooling pattern P2 is performed about once every 60 minutes, the frost formed on the heat transfer tubes 15 is generally in the early stage of frost formation (frost 10 (a) and (b)), the roots of the frost columns 33, 33, . . . , and the ice-air mixtures 34, 34, . good too. and ice/air mixtures 34, 34, . parts can be dissolved. By these, frost formation can be suppressed in a short time.

Here, the predetermined time of holding the surface temperature of the heat transfer tube 15 in a low temperature range of −1° C. to about 0° C. for 4 minutes ensures frost formation by the amount of heat transferred from the inside of the heat transfer tube 15 to the frost. It was optimized through repeated experiments so as to satisfy both the viewpoint of suppressing the temperature and the viewpoint of preventing an excessive temperature rise in the refrigerator. In addition, especially in the latter half of the constant temperature process α2 (for example, between 3 minutes and 4 minutes after the start of the constant temperature process α2), the effect on the internal temperature is small, so it may exceed 0 degrees, for example, the defrosting operation. In the first constant temperature process α2 after D, the temperature may be set to be in the range of −1° C. to 0° C. for 3 minutes after the start. The predetermined time for the constant temperature process α2 may be appropriately changed to less than 4 minutes, 5 minutes or more depending on the actual environment.

In addition, in the frost suppression cooling pattern P2, the temperature of the evaporator 8 is maintained near 0 degrees, and the heat quantity of the frost columns 33, 33, ... and the ice/air mixtures 34, 34, ... Since the circulating air takes it away, the outlet temperature of the circulating air that has passed through the evaporator 8 is around 0 degrees on average (see FIG. 8). Since the cold insulation chamber 5 is continuously cooled by this circulating air, an excessive temperature rise in the cold insulation chamber 5 is prevented. Furthermore, in the frost suppression cooling pattern P2, the amount of heat required to suppress frost formation is less than in the defrosting operation of the heating method or the off-cycle method, which will be described later. high thermal efficiency.

From these things, in the cooling operation C, by repeatedly performing the normal cooling pattern P1 and the frost formation suppression cooling pattern P2, the time until the maturity of the frost layer that requires the defrosting operation D (the time of the evaporator 8 desired or more cooling capacity) can be ensured for 12 hours or longer (for a long time) after the previous defrosting operation D was started. That is, it is possible to suppress the amount of frost forming over a long period of time.

Further, as shown in FIG. 8, in the frost suppression cooling pattern P2, although the inside temperature rises to a maximum of around 2.0 degrees and the article temperature rises to a maximum of around 3.0 degrees, it is higher than the normal cooling pattern P1. Since the frost formation suppression cooling pattern P2 is relatively short and the temperature rise is small, the effect is slight when considering the entire cooling operation C, and the normal cooling pattern P1 can be quickly restored. In the entire cooling operation C, the inside temperature is maintained at an average of about 0.0°C, and the article temperature is maintained at an average of about 2.0°C.

In addition, in the frost suppression cooling pattern P2, the time during which the evaporator 8 is in the low temperature range (-1°C to around 0°C) is measured for 4 minutes, so that the normal cooling pattern P1 is changed from the frost suppression cooling pattern P2 to the normal cooling pattern P1. , the article temperature does not rise easily.

The time for switching from the normal cooling pattern P1 to the frost formation suppression cooling pattern P2 can be freely changed, but the frost formation suppression cooling pattern P2 is performed at a frequency of once or more in about 60 minutes, and at the initial stage of frost formation, It is preferable to perform the frost formation suppression cooling pattern P2. As another example, for example, the frost suppression cooling pattern P2 is performed every 60 minutes for 3 hours after the completion of the defrosting operation D, every 50 minutes for 6 hours after that, and every 40 minutes for 3 hours thereafter. control may be performed so that the time between the frost formation suppression cooling pattern P2 is shortened.

Next, the operating mode of the piping system F of the refrigeration cycle in the defrosting operation D will be described. It should be noted that the description of the operation mode of the piping system F of the refrigeration cycle in which the evaporator 8 is in the normal cooling pattern P1 or the frost formation suppression cooling pattern P2 will be omitted.

As shown in FIG. 9B, the temperature rise process β1 of the defrosting operation D is started when 12 hours have passed since the previous temperature rise process β1 was started, and The temperature rise process α1 of the frost formation suppression cooling pattern P2 is the same as the temperature rise process α1 except that the surface temperature of the heat transfer tube 15 is raised to +3° C. or higher (see FIG. 7).

As shown in FIG. 7, in the temperature rise process β1, while the surface temperature of the heat transfer tube 15 is raised, the temperature rise of the heat transfer tube 15 is Frost formed on the surface of the heat transfer tube 15 deprives the heat transfer tube 15 of heat quantity, thereby stagnating. In this embodiment, since the normal cooling pattern P1 and the frost formation suppression cooling pattern P2 are repeatedly performed in the cooling operation C, the stagnation of temperature rise can be ended in a short time.

As shown in FIG. 9B, in the constant temperature process β2, the time during which the surface temperature of the heat transfer tube 15 is continuously +3°C or higher is measured by the timer M3 for 7 minutes, and after the constant temperature process β2, the The temperature constant process α2 of the frost suppression cooling pattern P2 is the same except that the second solenoid valve S2 is closed, the time is measured by the timer M4 for 4 minutes, and the process proceeds to the pressure holding process β3.

In the defrosting operation D, the surface temperature of the heat transfer tubes 15 is raised to 0° C. or higher, and the temperature of +3° C. or higher is maintained continuously for 7 minutes. Even in the frost layer maturity period), the parts of the frost that contact the surface of the heat transfer tube 15 are melted one after another, and the frost falls without melting the entire frost mass, so it can be removed in a short time. Frost can be done. In addition, since the first temperature sensor H1 and the second temperature sensor H2 are arranged at positions separated from each other on the left and right sides of the upstream straight pipe portion 15a' where frost tends to adhere, frost on the entire surface of the heat transfer tube 15 is sufficiently removed. can be defrosted to

In the pressure holding process β3, the second solenoid valve S2 is closed while the surface temperature of the heat transfer tube 15 is +3° C. or higher, so that the heat transfer tube 15 is prevented from being excessively heated. In addition, since the frost-free state is maintained for 4 minutes, the water adhering to the surface of the heat transfer tube 15 can be drained after the frost is melted. As a result, even if the normal cooling pattern P1 is resumed, the water adhering to the surface of the heat transfer tube 15 is prevented from freezing on the surface of the heat transfer tube 15 .

As shown in FIG. 9(b), when 4 minutes have passed since the pressure holding process β3 was started and the time measured by the timer M4 has passed, the control section opens the first solenoid valve S1 and the second solenoid valve S2. starts the normal cooling pattern P1. As a result, similar to the frost formation suppression cooling pattern P2, it is possible to suppress the influence on the inside temperature and the article temperature.

In the defrosting operation D, the inside temperature is about 5.0 degrees on average and about 10.0 degrees at maximum, and the article temperature is about 3 degrees on average and about 6.0 degrees at maximum. That is, compared with the defrosting operation by the heating method or the off-cycle method, which will be described later, the rate of increase in the internal temperature is low, and the effect on the displayed products is small.

The time for switching from the previous defrosting operation D to the next defrosting operation D can be freely changed, but it is preferable to set it outside business hours. If the closing time is 21:00, the defrosting operation D may be performed at 22:00 and 8:00. As another example, the surface temperature of the heat transfer tubes 15 may be used to detect that the frost layer is mature (initial state), and the defrosting operation D may be performed during the frost layer maturity.

Note that when the defrosting suppression cooling pattern P2 and the defrosting operation D are performed at the same time, the defrosting operation D is given priority.

In addition, defrosting only by the heating method using radiant heat from an external heat source such as a heater (hereinafter referred to as "heating method defrosting") and defrosting only by the off-cycle method by natural temperature rise or outside air (hereinafter referred to as " For defrosting of the off-cycle method"), first, the second solenoid valve S2 in this embodiment is closed, so that the suction of the compressor 21 causes the evaporation pressure of the refrigerant 16 in the heat transfer tube 15 to rise rapidly. Since the temperature of the refrigerant 16 has dropped instantaneously (for example, -20 degrees), the defrosting is performed, which takes a long time. In addition, off-cycle defrosting takes time, so the temperature inside the refrigerator rises to, for example, 16 to 18 degrees Celsius. There is a risk that the defrost will increase more than the defrosting of the off-cycle method.

As described above, the freezer/refrigerator showcase 1 of the present embodiment alternately performs the normal cooling pattern P1 and the frost formation suppression cooling pattern P2, thereby suppressing the temperature rise of the inside temperature of the evaporator 8. Since it is possible to reduce the amount of frost that forms on the surface, the interval until the defrosting operation D can be lengthened. As a result, the product can be kept cold for a long time (12 hours or more) in a substantially constant temperature zone (average temperature inside the refrigerator: about 0 degrees) lower than the temperature zone (average temperature inside the refrigerator: about 5 degrees) in the defrosting operation D. can be done. As a result, the product is sufficiently cooled to prevent spoilage.

In addition, since the temperature of the evaporator 8 can be raised by increasing the pressure inside the evaporator 8, the temperature control of the evaporator 8 is easy, and the temperature of the frosted portion from the inside of the evaporator 8 is raised. By doing so, the frost can be easily dropped without melting the whole, so the efficiency of frost formation suppression is good.

Also, by closing the first solenoid valve S1, the pressure in the evaporator 8 increases and the temperature of the evaporator 8 increases, so the temperature control of the evaporator 8 is easy.

In addition, since the desired or more cooling capacity of the evaporator 8 can be secured for 12 hours or more, the cooling capacity during business hours can be covered by a refrigeration cycle having one evaporator 8 . As a result, for example, using a refrigeration cycle in which multiple evaporators are connected in parallel, there is no need to maintain the cooling capacity during business hours by alternately operating multiple evaporators. It is possible to omit the cost and the space for arranging an additional evaporator.

Although the embodiments of the present invention have been described above with reference to the drawings, the specific configuration is not limited to these embodiments, and any changes or additions within the scope of the present invention are included in the present invention. be

For example, in the above embodiment, the refrigerating cycle has been described as having one evaporator 8, but the present invention is not limited to this, and a plurality of evaporators may be connected in parallel.

Further, the evaporator 8 has been described as a mode in which the pressure is increased by closing the first electromagnetic valve S1, but the present invention is not limited to this, and the pressure of the refrigerant 16 sent to the evaporator 8 is increased, There is no limitation as long as the pressure inside the evaporator 8 is increased, such as by narrowing the flow path on the downstream side of the evaporator 8 . Furthermore, in order to raise the temperature of the evaporator 8 and the frost, radiant heat from an external heat source such as a separate heater may be used.

The frost suppression cooling pattern P2 has been described as a mode in which the temperature rising process α1 is switched to the constant temperature process α2 in response to the fact that the surface temperature of the heat transfer tube 15 reaches −1°C, but the temperature is not limited to −2°C. It may be switched in response to reaching any temperature in the range of to 0 degrees (for example, -2 degrees or -1.5 degrees).

In addition, the low temperature range of the frost suppression cooling pattern P2 is -1 degree to around 0 degree, and although it has been described as a mode in which it may exceed 0 degree, it is not limited to the first temperature sensor H1 or the second temperature sensor H1. When any of the temperatures individually measured by the temperature sensor H2 exceeds 0°C, the first solenoid valve S1 may be immediately opened to shift to the normal cooling pattern P1. A closing operation (see FIG. 6) may be performed to stop the temperature rise of the heat transfer tubes 15 . With these aspects, it is possible to further prevent an increase in the internal temperature and the article temperature.

The time measuring means has been described as a mode in which the timers M1 to M5 are used, but the present invention is not limited to this. Any, but not limited.

In the defrosting operation D, the closing operation of the first solenoid valve S1 has been described as a mode in which the temperature of the heat transfer tube 15 is raised to +3 degrees or higher. It may be in a mode of frost operation, for example, may be a mode in which the temperature is raised to +1°C or higher or +5°C or higher, and is not limited.

1 refrigerated showcase 5 cold storage compartment (inside)
8 evaporator C cooling operation D defrosting operation M1 to M5 timer (time measuring means)
P1 Normal cooling pattern P2 Frost formation suppression cooling pattern S1 First solenoid valve

Claims (3)

A freezer/refrigerator showcase that performs a cooling operation to cool the inside of the refrigerator during the defrosting operation of the evaporator,
A solenoid valve is connected to the downstream side of the evaporator,
The cooling operation is performed in a lower temperature range and in a shorter time than the normal cooling pattern for cooling the evaporator and the defrosting operation, and closes the electromagnetic valve to increase the pressure inside the evaporator. and a frost formation suppression cooling pattern that raises the temperature of
In the frost suppression cooling pattern, when the temperature of the evaporator reaches a predetermined temperature of 0 degrees or less and near 0 degrees, the time is measured by the time measuring means, and the measured time becomes the predetermined time. A freeze/refrigerate showcase characterized in that the frost formation suppression cooling pattern is occasionally switched to the normal cooling pattern. 2. The freezer/refrigerated showcase according to claim 1 , wherein said time measuring means starts measuring the predetermined time from a predetermined temperature within a range of -2 degrees to 0 degrees. 3. The freezer/refrigerator showcase according to claim 1 , wherein the frost formation suppression cooling pattern is performed at predetermined intervals in the cooling operation.

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