JP2018029657A - Frozen/refrigerated showcase - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a frozen/refrigerated showcase that suppresses a rise of an internal temperature by defrosting and has a high thermal efficiency.SOLUTION: A frozen/refrigerated showcase 1 is provided for using a refrigerating cycle C with evaporators 8F, 8R, and includes multiple evaporators 8F, 8R and an evaporating pressure adjusting device 20 capable of adjusting the evaporating pressure of refrigerant 16 supplied in each evaporator. The frozen/refrigerated showcase has: a cooling operation pattern α1 for cooling all evaporators 8F, 8R in the refrigerating cycle C; and defrosting operation patterns β1, β1' where at least one evaporator performs cooling after completion of the cooling operation pattern α1 and the evaporating pressure of the coolant is increased by the evaporating pressure adjusting device 20, and thereby the defrosting of at least one other evaporator is performed. Operation pattern units U, U' are repeatedly performed during a predetermined period by the combination of the cooling operation pattern α1 and the defrosting operation patterns β1, β1'.SELECTED DRAWING: Figure 7

Description

  The present invention relates to a frozen / refrigerated showcase used for displaying frozen foods, fresh foods and the like in food departments such as supermarkets and convenience stores.

  In supermarkets and convenience stores, frozen and refrigerated showcases are arranged to display frozen foods and fresh foods while frozen or refrigerated. The refrigerated / refrigerated showcase includes a case body composed of an outer box and an inner box, and an evaporator and a blower installed in a ventilation path formed between the outer box and the inner box. The evaporator can cool the air around the evaporator by evaporating heat when the refrigerant flowing into the evaporator evaporates, and the air cooled by the evaporator is stored in the case body by the blower. Frozen foods, fresh foods, etc. sent to the inside and displayed in the warehouse are frozen or refrigerated.

  In such a refrigeration / refrigeration showcase, by continuing the cooling operation of the evaporator, frosting occurs in the evaporator, and the cooling capacity of the evaporator decreases as frosting progresses. Therefore, a freezing / refrigerating showcase as disclosed in Patent Documents 1 and 2 has been developed.

  In the freezing / refrigeration showcase shown in Patent Document 1, the evaporator is heated by a heater after business hours to defrost frost adhering to the evaporator.

  Moreover, the freezing and refrigeration showcase as shown in patent document 2 prevents the amount of frost formation of an evaporator from increasing by performing a short defrosting (defrosting operation pattern) during business hours, The cooling capacity of the evaporator is prevented from gradually decreasing during business hours. The short-time defrosting during business hours in Patent Document 2 is performed by an off-cycle method in which the refrigerant flow is stopped and defrosting is performed by the temperature of the outside air, so compared to using a heat source having a large amount of heat such as a heater. This prevents the temperature inside the chamber from rising rapidly.

No. 7-12861 (Page 2, Fig. 1) Japanese Examined Patent Publication No. 7-109345 (page 4, FIG. 5)

  However, in the refrigeration / refrigeration showcase of Patent Document 2, although the temperature inside the cabinet is prevented from rising rapidly during a short period of defrosting, the off-cycle method stops the flow of the refrigerant and Since it is thawing only by blowing, it takes time to melt the frost. For this reason, during defrosting, the evaporator cannot be cooled, and the internal temperature rises, and it takes a long cooling time to cool again to the desired internal temperature after defrosting is completed. The thermal efficiency of the case is not sufficient.

  The present invention has been made paying attention to such problems, and an object of the present invention is to provide a freezing / refrigeration showcase with high thermal efficiency by suppressing an increase in the internal temperature due to defrosting.

In order to solve the above problems, the freezing and refrigeration showcase of the present invention is:
A refrigeration / refrigeration showcase using a refrigeration cycle equipped with an evaporator,
Equipped with a plurality of evaporators and an evaporation pressure adjusting device capable of adjusting the evaporation pressure of the refrigerant supplied into each evaporator,
A cooling operation pattern in which all the evaporators in the refrigeration cycle perform cooling;
A defrosting operation pattern in which at least one evaporator performs cooling after the cooling operation pattern ends, and at least one other evaporator is defrosted by increasing the evaporation pressure of the refrigerant by the evaporation pressure adjusting device; Have
An operation pattern unit based on a combination of the cooling operation pattern and the defrosting operation pattern is repeatedly performed for a predetermined period.
According to this feature, the defrosting operation pattern is always performed after the completion of the cooling operation pattern with a high cooling capacity, so that the growth of frost can be suppressed and the thermal efficiency can be increased, and the operation pattern unit can be repeatedly operated for a predetermined period. Therefore, at least one evaporator is always in a cooling state, the rise in the internal temperature is suppressed, the internal temperature is easily returned to the temperature at the time of cooling, and the thermal efficiency is high.

The defrosting operation pattern is characterized in that a plurality of the evaporators are sequentially defrosted.
According to this feature, since a plurality of evaporators are defrosted sequentially, the frost unevenness of each evaporator is reduced, so that the evaporators can each stably exhibit cooling capacity and increase thermal efficiency. .

The cooling operation pattern is performed for a longer time than the defrosting operation pattern.
According to this feature, the rise in the internal temperature due to the defrosting operation pattern can be suppressed, and the return to the desired internal temperature due to the cooling operation pattern can be performed in a short time.

A second cooling operation pattern in which cooling is performed in all the evaporators in the refrigeration cycle, and a second defrosting which is performed for a longer time than the defrosting operation pattern of the operation pattern unit after the end of the second cooling operation pattern. The operation pattern is performed after the operation pattern unit is repeated for a predetermined period.
According to this feature, the frost accumulated in the evaporator can be reliably defrosted by the second defrosting operation pattern that is performed at a predetermined timing for a long time, and the thermal efficiency is maintained in a high state.

The evaporating pressure adjusting device is an electronic evaporating pressure adjusting valve capable of adjusting an evaporating pressure of a refrigerant supplied into the evaporator.
According to this feature, the evaporating pressure of the refrigerant supplied into the evaporator can be adjusted stepwise by the electronic evaporating pressure adjusting valve. Defrosting can be performed.

1 is a cross-sectional view showing a freezing / refrigerating showcase in Embodiment 1. FIG. It is a block diagram which shows the structure of the piping system of a refrigerating cycle. It is a block diagram which shows the evaporator and evaporation pressure adjustment apparatus (switching circuit) at the time of cooling operation. It is a block diagram which shows the evaporator and evaporation pressure adjustment apparatus (switching circuit) at the time of a defrost operation. It is a table | surface figure which shows the experimental result at the time of actually operating the freezing and refrigeration showcase in Example 1. FIG. It is a graph which shows the internal temperature in Example 1, and the surface temperature of each evaporator. 3 is a graph showing an operation mode of each evaporator in Example 1. It is an enlarged view of the enclosure part A in FIG. 6, (a) is a graph which shows the internal temperature and the surface temperature of each evaporator, (b) is a graph which shows the operation | movement aspect of each evaporator. It is an enlarged view of the enclosure part B in FIG. 6, (a) is a graph which shows the internal temperature and the surface temperature of each evaporator, (b) is a graph which shows the operation | movement aspect of each evaporator. It is a table | surface figure which shows the operation | movement aspect of each solenoid valve which comprises the evaporator and evaporation pressure adjustment apparatus (switching circuit) in Example 1. FIG. (A) is a block diagram which shows the evaporator and switching circuit at the time of the cooling operation in Example 2, (b) is a block diagram which shows the evaporator and switching circuit at the time of the defrost operation in Example 2. . It is a block diagram which shows the structure of the evaporator in Example 3, and an evaporation pressure adjusting device (electronic evaporation pressure adjusting valve).

  EMBODIMENT OF THE INVENTION The form for implementing the freezing / refrigeration showcase which concerns on this invention is demonstrated below based on an Example.

  The freezing / refrigeration showcase according to the first embodiment will be described with reference to FIGS. Hereinafter, the left side of FIG. 1 will be described as the front side (front side) of the refrigeration / refrigeration showcase, and the description will be made with reference to the vertical and horizontal directions when viewed from the front side.

  As shown in FIG. 1, the refrigerated / refrigerated showcase 1 is installed in a store that mainly handles foods such as stores, supermarkets, and convenience stores, and the product is kept cold or frozen while keeping the product at a low temperature. A plurality of shelves 6, 6,... For displaying products are installed in the cold storage room 5, which is installed for display and surrounded by an inner box 3 that opens at the front side. A product (not shown) can be displayed on the bottom 3b provided at the lower part of 3 so that a large number of products can be placed.

  The refrigerated / refrigerated showcase 1 includes a substantially U-shaped outer box 2 having a front surface (left side in the figure) opened and a substantially U-shaped inner box 3 having a front surface opened to the inside. The interior space is a cold storage room 5 (inside the cabinet). The rear ends of brackets 28, 28,... Extending in the front-rear direction are attached to the back surface portion 3a of the inner box 3, and the shelf boards 6, 6,. . A product (not shown) is displayed on the upper surfaces of the shelf boards 6, 6... And the bottom 3 b of the inner box 3.

  A ventilation path 7 is formed between the outer box 2 and the inner box 3, and evaporators 8F and 8R and a blower 9 are installed on the vertical part and the horizontal bottom part of the ventilation path 7, respectively. As will be described later, the evaporators 8F and 8R can cool the surrounding air. Further, heat insulating materials 29 and 29 are provided on the front sides of the evaporators 8F and 8R, respectively, heat exchange between the evaporators 8F and 8R, and the cold insulation chamber 5 side through the evaporator 8F and the inner box 3. The heat exchange with is suppressed. A cold air outlet 10 that communicates with the air passage 7 is formed downward at the front end of the upper portion of the case body, and a cold air inlet 11 that opens upward is formed at the upper end of the lower front end of the case body. .

  When the blower 9 is operated, the cold air cooled by the evaporators 8F and 8R flows upward in the ventilation path 7 as indicated by the arrow, and blows out from the cold air outlet 10 toward the lower inlet 11. Is done. As a result, a cold air curtain 12 is formed on the open surface of the front surface of the case body, and a part of the cold air flows into the cold insulation chamber 5 so that the displayed product is kept cold. These evaporators 8F and 8R are set so that the temperature of the air blown from the cold air outlet 10 (air outlet temperature) is substantially 0 ° C. (see FIG. 5), and only the evaporator on one side is provided. It has a capacity capable of cooling the outlet temperature to 0 ° C. even in operation. The evaporator may have a capacity that cools the outlet temperature to 0 ° C. when both the evaporators 8F and 8R are operated.

  Next, the evaporators 8F and 8R in the freezer / refrigerated showcase 1 will be described. As shown in FIG. 1, the evaporator 8 </ b> F is disposed on the front side of the ventilation path 7, and the evaporator 8 </ b> R is disposed on the rear side of the ventilation path 7. In addition, although the present Example demonstrated the case where evaporator 8F, 8R was arrange | positioned forward and backward, two evaporators may be arrange | positioned up and down, and may be arrange | positioned right and left.

  As shown in FIG. 2, the evaporator 8F and the evaporator 8R include heat transfer tubes 15 and 15 which are copper tubes through which the refrigerant 16 flows, and the heat transfer tubes 15 and 15 include a plurality of fins (not shown). It extends so as to meander through, and this increases the contact area between the heat transfer tubes 15 and 15 and the surrounding air, efficiently blows air from the blower 9, and improves the cooling efficiency. The heat transfer tubes 15 and 15 are not limited to copper tubes, and may be metal or resin tubes having high thermal conductivity.

  Further, a temperature sensor (not shown) for measuring the surface temperature is provided at a bent portion (so-called U-bend portion) where heat exchange does not easily occur in the heat transfer tubes 15 and 15 of the evaporator 8F and the evaporator 8R. The temperature sensor is connected to a control unit (not shown), and the control unit is connected to three-way switching valves 25 and 25 described later. By measuring the surface temperature at the bent portions of the heat transfer tubes 15 and 15 with a temperature sensor, the control unit can determine the frost formation state on the outer surfaces of the heat transfer tubes 15 and 15 in the defrosting operation pattern β described later. . A temperature sensor (not shown) is also provided in the vicinity of the shelves 6, 6,... And in the vicinity of the cold air outlet 10 to measure the internal temperature and the temperature of the air that has passed through the evaporator 8F and the evaporator 8R. It is possible.

  In the present embodiment, the example of measuring the surface temperature of the bent portion of the heat transfer tubes 15 and 15 with the temperature sensor has been shown, but the surface temperature of other portions of the heat transfer tubes 15 and 15 is measured. It may be. Further, in this embodiment, the surface temperature of the heat transfer tubes 15 and 15, the temperature of the air that has passed through the evaporator 8F and the evaporator 8R, and the internal temperature are measured by each temperature sensor. What is necessary is just to be provided in the position which can measure at least 1 place among the surface temperature of the heat exchanger tubes 15 and 15, the temperature of the air which passed the evaporator 8F and the evaporator 8R, or the internal temperature.

  The evaporator 8F and the evaporator 8R are a part of the piping system C of the refrigeration cycle, and are arranged in parallel with the circuit in the piping system C of the refrigeration cycle. Specifically, at the upstream end of each of the evaporator 8F and the evaporator 8R, the expansion valves 17 and 17 are evacuated by reducing the pressure of the liquefied refrigerant 16 to a predetermined evaporation pressure (temperature). And a liquid receiver 18 for storing the refrigerant 16 is connected to the expansion valves 17 and 17 through supply pipes 19 and 19 respectively connected thereto. An opening / closing valve 14 is provided in the supply pipe 19 between the liquid receiver 18 and the expansion valves 17, 17, and the flow path between the liquid receiver 18 and the expansion valves 17, 17 can be appropriately opened / closed. It has become.

  Further, a switching circuit 20 (evaporation pressure adjusting device) is connected to each downstream end of the evaporator 8F and the evaporator 8R, and in the evaporator 8F and the evaporator 8R on the downstream side of the switching circuit 20. A compressor 21 that sucks the vaporized refrigerant 16 evaporated in step 1 and compresses the refrigerant 16 and sends it to the liquid receiver 18 side is connected. The compressor 21 is connected to the liquid receiver 18 via the condenser 22. It is connected to the. The condenser 22 releases the heat of the refrigerant 16 in the high-pressure vaporized state compressed by the compressor 21 to the outside to make the refrigerant 16 liquefied.

  In FIG. 2, the refrigerant 16 in the liquid (liquefied) state is indicated by a solid line, and the refrigerant (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 ° C. to 40 ° C. in summer and about 20 ° C. in winter.

  As shown in FIGS. 2 to 4, a switching circuit 20 is connected to the downstream side of the evaporator 8 </ b> F and the evaporator 8 </ b> R. The switching circuit 20 includes first pipes 23 and 23 and second pipes 24 and 24 that communicate with the heat transfer pipes 15 and 15 of the evaporator 8F and the evaporator 8R, respectively. Electromagnetic valves SV2 and SV4 are provided on the upstream side, and electromagnetic valves SV1 and SV3 are provided on the upstream side of the second pipes 24 and 24, respectively. The second pipes 24 and 24 are connected to each other to form a merging pipe 24a. One evaporating pressure adjusting valve 26 is upstream of the merging pipe 24a, and a non-return is downstream of the evaporating pressure adjusting valve 26. A valve 27 is provided.

  In the switching circuit 20, the solenoid valves SV1 and SV3 close the second pipes 24 and 24, respectively, and the solenoid valves SV2 and SV4 are the heat transfer pipes 15 and 15 of the evaporator 8F and the evaporator 8R and the first pipes 23 and 23, respectively. And the electromagnetic valve SV1 close the second pipe 24, and the electromagnetic valve SV2 allows the heat transfer pipe 15 of the evaporator 8F and the first pipe 23 to communicate with each other at the same time. The valve SV4 closes the first pipe 23, the electromagnetic valve SV3 communicates with the heat transfer pipe 15 of the evaporator 8R and the second pipe 24 (see FIG. 4), and the electromagnetic valve SV2 has the first pipe 23. The electromagnetic valve SV1 causes the heat transfer tube 15 of the evaporator 8F to communicate with the second pipe 24. At the same time, the electromagnetic valve SV3 closes the second pipe 24, and the electromagnetic valve SV4 transmits to the evaporator 8R. A mode of communicating the heat pipe 15 and the first pipe 23 (see FIG. It has become a possible switched omitted), to.

  These solenoid valves SV1 to SV4 are switched and controlled at predetermined time intervals according to a time table by a control unit (not shown). By switching these solenoid valves SV1 to SV4, as shown in FIG. 5, the cooling operation in which the evaporator 8F and the evaporator 8R (all evaporators) in the refrigeration cycle cool the surrounding air. The pattern α and one of the evaporator 8F and the evaporator 8R (at least one evaporator) perform the cooling operation, and the evaporation pressure adjusting device increases the evaporation pressure of the refrigerant 16 to increase the evaporator 8F and the evaporator 8R. These can be switched to defrosting operation patterns β and β ′ for performing a defrosting operation for removing frost adhering to the heat transfer tube 15 of the other (at least one other evaporator). The operations of the cooling operation pattern α and the defrosting operation patterns β and β ′ of the evaporator 8F and the evaporator 8R will be described in detail later.

  In the present embodiment, the operation pattern of the evaporator 8F and the evaporator 8R can be switched by using only the operation of switching the electromagnetic valves SV1 to SV4 and also using the single evaporation pressure adjusting valve 26. The cost for manufacturing 20 can be reduced.

  The evaporation pressure adjusting valve 26 is a valve body that opens the flow path in the merging pipe 24a at a set pressure or higher and closes the flow path in the merging pipe 24a at a pressure lower than the set pressure. The evaporator 8F And the pressure of the refrigerant | coolant 16 which flows in into the evaporator 8R is adjusted. This set pressure is set to a pressure higher than a predetermined evaporation pressure of the refrigerant 16 in the evaporator 8F and the evaporator 8R when the evaporator 8F and the evaporator 8R are in the cooling operation state.

  The check valve 27 prevents the downstream refrigerant 16 from flowing back to the evaporation pressure regulating valve 26 side when the flow path of the refrigerant 16 is switched to the second piping 24, 24 side by the electromagnetic valves SV1 to SV4. It is out.

  Next, an operation mode of the piping system C of the refrigeration cycle in the cooling operation pattern α in which both the evaporator 8F and the evaporator 8R are the cooling operation will be described. As shown in FIGS. 2 and 3, in the cooling operation pattern α, the second pipes 24, 24 are closed by the electromagnetic valves SV 1, SV 3, respectively, and the heat transfer pipes 15, 15 and the first pipe 23 are closed by the electromagnetic valves SV 2, SV 4. , 23 are communicated with each other. When the compressor 21 is operated, the liquefied refrigerant 16 stored in the liquid receiver 18 is sent to the evaporator 8F and the evaporator 8R through the supply pipes 19 and 19 and the expansion valves 17 and 17. The refrigerant 16 in the liquefied state is decompressed by the expansion valves 17 and 17 so as to have a predetermined evaporation pressure, and is in a vaporized state. The vaporized refrigerant 16 that has flowed into the heat transfer tubes 15 and 15 of the evaporator 8F and the evaporator 8R removes heat from the air in the ventilation path 7, whereby the air in the ventilation path 7 is cooled.

  The vaporized refrigerant 16 that has passed through the heat transfer tubes 15 and 15 of the evaporator 8F and the evaporator 8R flows into the first pipes 23 and 23 that communicate with the heat transfer tubes 15 and 15, respectively. Through the liquid receiver 18. By repeating this operation, the cooling operation pattern α of the evaporator 8F and the evaporator 8R is continuously continued.

  As shown by reference numerals P3, P6, P7 (1) and P8 in FIGS. 7 and 10, in the case of the cooling operation pattern α in which both the evaporator 8F and the evaporator 8R are in the cooling operation state, The cooling capacity of the refrigerated showcase 1 is high, and the interior can be efficiently cooled. The surface temperatures of the heat transfer tubes 15 and 15 of the evaporator 8F and the evaporator 8R at the time of the cooling operation pattern α are around −10 ° C., and the inside temperature in the cold insulation chamber 5 is maintained at about 2 ° C. (See FIGS. 5 and 6). In addition, the inside temperature here refers to the temperature in the vicinity of the shelf boards 6, 6,. In the present embodiment, the cooling operation pattern α includes the first cooling operation pattern α1 (see P7 (1) in the table of FIG. 10) and the second cooling operation pattern α2 (FIG. 10) based on the operation timing and the like. P8 in the table) and the third cooling operation pattern α3 (see P3 and P6 in the table in FIG. 10) are described separately, but each is performed in the same operation mode.

  Next, an operation mode of the piping system C of the refrigeration cycle in the defrosting operation pattern β in which the evaporator 8F is the defrosting operation and the evaporator 8R is the cooling operation will be described. The operation mode of the piping system C in the refrigeration cycle of the defrosting operation pattern β ′ in which the evaporator 8F is in the cooling operation and the evaporator 8R is in the defrosting operation has substantially the same configuration as that in the defrosting operation pattern β. Therefore, the description is omitted. Further, since the cooling operation of the evaporator 8R has the same configuration as the cooling operation of the evaporator 8R in the cooling operation pattern α described above, only the defrosting operation of the evaporator 8F will be described, and the cooling operation of the evaporator 8R will be described. Description is omitted.

  As shown in FIGS. 2 and 4, during the defrosting operation pattern β, the electromagnetic valve SV2 closes the first pipe 23, and the electromagnetic valve SV1 connects the heat transfer pipe 15 and the second pipe 24 of the evaporator 8F. Communicate. The vaporized refrigerant 16 that has passed through the heat transfer tube 15 of the evaporator 8F flows into the second pipe 24 that communicates with the heat transfer tube 15.

  At this time, the refrigerant 16 in the heat transfer pipe 15 and the second pipe 24 is at a pressure (predetermined evaporation pressure) lower than the set pressure of the evaporation pressure adjustment valve 26 as described above. 26 is a state in which the junction tube 24a is closed. The refrigerant 16 flowing into the junction pipe 24a is blocked by the closed evaporation pressure adjusting valve 26, so that the section from the expansion valve 17 provided upstream of the evaporator 8F to the closed evaporation pressure adjusting valve 26 is provided. As the pressure increases, and the pressure rises above the set pressure, the evaporating pressure adjustment valve 26 opens, and the refrigerant 16 is allowed to pass through the junction pipe 24a. In other words, the evaporating pressure adjusting valve 26 controls the evaporating pressure of the refrigerant 16 flowing into the section from the expansion valve 17 to the evaporating pressure adjusting valve 26 so that it does not drop below the set pressure.

  According to this, by switching the evaporator 8F from the cooling operation to the defrosting operation by the switching circuit 20 using the evaporation pressure adjusting valve 26, the refrigerant 16 that has flowed into the heat transfer pipe 15 of the evaporator 8F is adjusted to the evaporation pressure. Compressed by the valve 26, the evaporation pressure becomes higher than that during the cooling operation, and the temperature rises to 0 ° C. or higher (for example, 5 ° C.). As described above, since the temperature of the refrigerant 16 can be changed by the switching circuit 20, the cooling operation and defrosting of the evaporator 8F can be performed while keeping the output of the compressor 21 constant, in other words, without changing the output of the compressor 21. Operation switching control is simple.

  Further, since the evaporation pressure of the refrigerant 16 in the evaporator 8F is increased by the evaporation pressure adjusting valve 26, the liquefied refrigerant 16 is difficult to flow into the expansion valve 17 on the evaporator 8F side, and the evaporator 8R side The amount of the refrigerant 16 flowing into the supply pipe 19 increases, and as a result, the amount of the vaporized refrigerant 16 flowing into the evaporator 8R increases, thereby improving the cooling capacity of the evaporator 8R.

  As indicated by reference numerals P1, 2 (β2) and P7 (2) (β1) in FIGS. 7 and 10, the temperature is 0 ° C. in the defrosting operation pattern β in which the evaporator 8F is in the defrosting operation. Heat is transferred from the inside of the heat transfer tube 15 to the outer surface of the heat transfer tube 15 by the heat transfer by the refrigerant 16 rising above. For this reason, the heat transfer tube 15 can be defrosted to every corner of the heat transfer tube 15 even if it is a bent portion that is particularly susceptible to frost formation. Moreover, since it can melt | dissolve from the adhesion surface (in other words, the root of frost) adhering to the outer surface of the heat exchanger tube 15, it is low temperature compared with the case where the radiant heat of external heat sources, such as a defrost heater, is utilized, and Frost melts in a short time and can be defrosted efficiently.

  Here, in the case of defrosting only by a heating method using a defrosting heater (in the case of the prior art), by heating the evaporator from the outside with the defrosting heater in a state where the flow of the refrigerant into the evaporator is stopped In order to perform defrosting, defrosting can be performed in a short time using the large amount of heat of the defrosting heater, but the evaporator is heated by the defrosting heater until the frost melts in a state where the cooling operation is stopped. In addition, there is a possibility that the internal temperature is raised more than necessary, and the products displayed in the internal compartment are deteriorated. Further, the off-cycle type defrosting that stops the flow of the refrigerant 16 is thawed only by the blower of the blower 9 (or the blower 9 is also stopped and naturally thawed), so it takes time until the frost is melted. The inside temperature has risen to, for example, about 7 to 8 ° C., and it has to be cooled again from the elevated temperature to the desired inside temperature, resulting in low thermal efficiency. .

  Further, in heating type defrosting and off-cycle type defrosting using only the defrosting heater 4, the flow of the refrigerant 16 to the evaporator can be stopped by closing the supply pipe with an on-off valve. Since it is general, immediately after closing the on-off valve, the evaporating pressure of the refrigerant 16 in the heat transfer tube 15 is suddenly lowered by the suction of the compressor 21, and the temperature of the refrigerant 16 instantaneously reaches, for example, −40 ° C. After that, the temperature of the heat transfer tube 15 gradually increases, and the surface temperature of the heat transfer tube 15 temporarily decreases, so that frost attached to the outer surface of the heat transfer tube 15 becomes difficult to melt. It was necessary to raise the temperature of the heat transfer tube 15 from the state, and it took a long time to shift to the defrosting operation. However, the evaporator 8F and the evaporator 8R of this embodiment are immediately switched by the switching circuit 20. Of refrigerant 16 To increase the degree, so that it is possible to perform switching between cooling operation and the defrosting operation in a short time. Furthermore, in the defrosting operation pattern β of the present embodiment, the evaporator 8R is performing the cooling operation when the evaporator 8F is performing the defrosting operation as compared to the off-cycle defrosting, so An increase in temperature can be suppressed.

  In addition, when the pressure in the section from the expansion valve 17 to the evaporation pressure adjustment valve 26 increases to a set pressure or higher, the evaporation pressure adjustment valve 26 is opened, so that the evaporation pressure adjustment valve 26 is open. The pressure in the section from the expansion valve 17 to the evaporation pressure adjusting valve 26 becomes the set pressure, and the evaporation temperature of the refrigerant 16 becomes a temperature corresponding to the set pressure. That is, the temperature is kept substantially constant, a rapid increase in the internal temperature can be prevented, and the defrosting operation is reliably performed without lowering the evaporation temperature. In addition, the refrigerant 16 that has passed through the evaporation pressure regulating valve 26 that has been opened due to the pressure increasing above the set pressure flows into the compressor 21 via the check valve 27.

  Next, one day operation modes of the evaporator 8F and the evaporator 8R in the present embodiment will be described with reference to FIGS. In the predetermined period shown in FIGS. 6 and 7, the freezing / refrigeration showcase 1 has the first defrosting operation pattern β1 or the first defrosting operation pattern β1 ′ after the end of the first cooling operation pattern α1. The operation pattern units U and U ′ (see FIG. 8B) are repeatedly performed. The predetermined period may be a period determined in advance as a time table or a period determined by the temperature obtained from the temperature sensor described above.

  In the present embodiment, units formed by a combination of the cooling operation pattern α (α1) and the defrosting operation pattern β (β1 or β1 ′) in a predetermined period are referred to as operation pattern units U and U ′. Furthermore, in the present embodiment, as shown in an enclosure B of FIG. 6, the first defrosting operation pattern β1 or the first defrosting operation pattern β1 or the first operation time except for a predetermined period in which the operation pattern units U and U ′ are repeatedly performed. The second defrosting operation pattern β2 or the second defrosting operation pattern β2 ′ described later in which the defrosting operation is performed for a longer time than the defrosting operation pattern β1 ′ is performed.

  In the present embodiment, the first defrosting operation pattern β1 (see FIG. 8) first after the end of the first cooling operation pattern α1 (see symbol P7 (1) in FIG. 8B) in the predetermined period described above. After the operation pattern unit U that performs the operation P8 (see symbol P7 (2) in FIG. 8B) is performed, the next first cooling operation pattern α1 (see the symbol P7 (1) in FIG. 8B). After completion, an operation pattern unit U ′ for performing the first defrosting operation pattern β1 ′ (see symbol P7 (3) in FIG. 8B) is performed, and such operation pattern units U and U ′ are displayed. By repeatedly performing for a predetermined period, the evaporator 8F and the evaporator 8R are sequentially defrosted.

  As shown in FIG. 8A showing the enclosure A in FIGS. 6 and 6, the first defrosting operation pattern β1 and the first defrosting operation pattern β1 in each operation pattern unit U performed during a predetermined period. 'Sometimes, the surface temperature of the heat transfer tube 15 of the evaporator 8F or 8R is set to a predetermined temperature lower than 0 ° C (around -1 ° C) in order to suppress the growth of frost attached to the outer surfaces of the heat transfer tubes 15 and 15. Since the defrosting operation is performed for a short time (about 3 minutes) until the temperature rises, the internal temperature is kept at about 2 ° C. without changing from the first cooling operation pattern α1. Here, suppressing the growth of frost includes not increasing the frost, reducing the frost, or completely removing the frost.

  More specifically, as shown in FIG. 8B and FIG. 10, first, in each operation pattern unit U performed in a predetermined period, the first cooling operation pattern α1 for about 15 minutes (in the table of FIG. 10). When the first defrosting operation pattern β1 of about 3 minutes is performed after the end of P7 (1) in the upper stage), the evaporator 8F switches from the cooling operation to the defrosting operation, and the first defrosting operation pattern When β1 (see P7 (2) in the table of FIG. 10) is started, the surface temperature of the heat transfer tube 15 of the evaporator 8F rapidly rises to around −1 ° C. (see FIG. 8A). This is because the solenoid valves SV1 and SV2 are switched and the refrigerant 16 in the evaporator 8F is adjusted by the evaporation pressure adjusting valve 26.

  In addition, the signs P3 and P6 in FIG. 8 (b) are defrosting recovery operations described later that are continuously performed before the first cooling operation pattern α1 of the operation pattern unit U indicated by the reference symbol P7 (1). The third cooling operation pattern α3 is shown. Furthermore, in the enclosure A of FIG. 6, the third cooling operation pattern α3 (P6) is performed as the defrosting return operation of the evaporator 8R. However, for the convenience of explanation, the defrosting return operation of the evaporator 8F is performed. The third cooling operation pattern α3 (P3) is also described.

  In the first defrosting operation pattern β1 in the operation pattern unit U, the evaporator 8F is switched from the defrosting operation to the cooling operation before the surface temperature of the heat transfer tube 15 of the evaporator 8F rises to 0 ° C. or more. Since the surface temperatures of the heat transfer tubes 15 and 15 of the 8F and the evaporator 8R are lowered, there is almost no change in the internal temperature from the state of the first cooling operation pattern α1, and the internal temperature is kept at about 2 ° C. .

  Then, after the above-described operation pattern unit U is completed, the process proceeds to the first cooling operation pattern α1 for about 15 minutes in the next operation pattern unit U ′ (see P7 (1) in the lower part of the table in FIG. 10). Then, the solenoid valves SV1 and SV2 are switched, and the evaporator 8F is switched from the defrosting operation to the cooling operation. After the end of the first cooling operation pattern α1, the evaporator 8R switches from the cooling operation to the defrosting operation, and the first defrosting operation pattern β1 ′ (see P7 (3) in the table of FIG. 10) starts. Is done.

  Even in the first defrosting operation pattern β1 ′ in the operation pattern unit U ′, the evaporator 8R is cooled from the defrosting operation to the cooling operation before the surface temperature of the heat transfer tube 15 of the evaporator 8R rises to 0 ° C. or more. Since the surface temperature of the heat transfer tubes 15 and 15 of the evaporator 8F and the evaporator 8R is lowered, there is almost no change in the internal temperature from the state of the first cooling operation pattern α1, and the internal temperature is 2 ° C. It is kept to a degree.

  As shown in FIGS. 6 and 7, in this embodiment, after the operation pattern units U and U ′ are repeated for a predetermined period, the evaporator 8F and the evaporator 8R (all evaporators) in the refrigeration cycle. The second cooling operation pattern α2 in which the cooling operation is performed (see P8 in the table of FIG. 10), and the first defrosting of the operation pattern units U and U ′ described above after the end of the second cooling operation pattern α2. A second defrosting operation pattern β2, β2 ′ (see P1, P2, and P4, 5 in the table of FIG. 10) that is performed for a longer time than the operation patterns β1, β1 ′ is performed.

  In the present embodiment, after the end of the second cooling operation pattern α2, a second defrosting operation pattern β2 (second defrosting operation pattern β2 ′) is performed, and the defrosting return operation described later is performed. After the operation pattern units U and U ′ are repeated for a predetermined period across the third cooling operation pattern α3 (see P3 and P6 in the table of FIG. 10), after the end of the next second cooling operation pattern α2 By performing the second defrosting operation pattern β2 ′ (second defrosting operation pattern β2 ′), the evaporator 8F and the evaporator 8R are sequentially defrosted.

  Further, as shown in FIG. 9A showing the enclosure B of FIGS. 6 and 6, during the second defrosting operation pattern β2 or the second defrosting operation pattern β2 ′, the heat transfer tubes 15, 15 In order to completely remove frost adhering to the outer surface, the defrosting operation takes a long time (about 30 minutes) until the surface temperature of the heat transfer tube 15 of the evaporator 8F or 8R rises to 0 ° C. or higher (5 ° C.). Since this is done, the internal temperature rises to about 4 ° C.

  More specifically, as shown in FIG. 10, when the operation of the second defrosting operation pattern β2 is performed after the second cooling operation pattern α2, the evaporator 8F is switched from the cooling operation to the defrosting operation. When the second defrosting operation pattern β2 (see P1 in the table of FIG. 10) is started, the surface temperature of the heat transfer tube 15 of the evaporator 8F rapidly rises to around −1 ° C. (FIG. 9 ( a)). This is because the solenoid valves SV1 and SV2 are switched and the refrigerant 16 in the evaporator 8F is adjusted by the evaporation pressure adjusting valve 26.

  Next, the surface temperature of the heat transfer tube 15 of the evaporator 8F gradually rises from around -1 ° C to around 0 ° C. This is because the surface temperature of the heat transfer tube 15 of the evaporator 8F is less likely to increase due to the remaining frost remaining on the outer surface of the heat transfer tube 15. Next, the surface temperature of the heat transfer tube 15 of the evaporator 8F rises again from around 0 ° C. to around 5 ° C. This is because the surface temperature is likely to rise again because the frost is completely or almost melted. In other words, when the surface temperature of the heat transfer tube 15 of the evaporator 8F rises to 0 ° C. or higher. It can be judged that the defrosting is almost completed. Further, since the surface temperature of the heat transfer tube 15 of the evaporator 8F is adjusted by the evaporation pressure adjusting valve 26 so that the evaporation pressure of the refrigerant 16 in the evaporator 8F becomes substantially constant, the second defrosting operation pattern β2. In this operation, the temperature does not rise above 5 ° C.

  Further, when the defrosting is completed, the internal temperature rises to around 4 ° C. as the surface temperature of the heat transfer tube 15 of the evaporator 8F rises to around + 5 ° C. This is because high temperature air outside the cold insulation chamber 5 flows into the cold insulation chamber 5 and circulates in a state where the cooling capacity of the evaporator 8F is reduced due to the rise in the surface temperature of the heat transfer tube 15.

  As shown in P1 in the table of FIG. 10, the defrosting of the heat transfer tube 15 of the evaporator 8F is almost completed, and the surface temperature of the heat transfer tube 15 of the evaporator 8F increases from 0 ° C. to around + 5 ° C. In the stage, when a state where a preset return temperature range (0 to 6 ° C. or more) of the heat transfer tube 15 is detected for several minutes is detected, the control unit moves to P2 in the table of FIG. 10 (return temperature operation). Then, as shown in P2 in the table of FIG. 10, the second draining time is set for a preset drainage time for dropping water droplets generated by melting of frost adhering to the surface of the heat transfer tube 15 of the evaporator 8F. The operation of the defrosting operation pattern β2 continues.

  Then, as shown in the table P3 in FIG. 10, the solenoid valves SV1 and SV2 are switched, the evaporator 8F is switched from the defrosting operation to the cooling operation, and the evaporator 8F defrosting recovery (removal of the evaporator 8F) is performed. (Return from frost operation to cooling operation). For about 10 minutes after the start of the defrosting recovery of the evaporator 8F, the third cooling operation pattern α3 (the first operation pattern unit performed in a predetermined period until the surface temperature of the heat transfer tube 15 of the evaporator 8F reaches around −10 ° C. The first cooling operation pattern α1 in U is continuous), and as the surface temperature of the heat transfer tube 15 of the evaporator 8F decreases, the inside temperature of the cool room 5 gradually decreases to about 2 to 3 ° C. It goes down.

  As shown in FIG. 10, after the second cooling operation pattern α2 (see P8 in the table of FIG. 10), the second defrosting operation pattern β2 ′ (see P4 and 5 in the table of FIG. 10). ), The evaporator 8R is switched from the cooling operation to the defrosting operation, and when the second defrosting operation pattern β2 ′ is started, the evaporator 8R is switched from the cooling operation to the defrosting operation. The second defrosting operation pattern β2 ′ is performed, the second defrosting operation pattern β2 ′ as the draining time (see P5 in the table of FIG. 10), and the third cooling as the evaporator 8R defrosting recovery. The operation pattern α3 (see P6 in the table of FIG. 10) is sequentially controlled. In addition, since the detail of the operation | movement aspect of 2nd defrost operation pattern (beta) 2 'is the same structure as the operation | movement aspect of evaporator 8F mentioned above, the operation | movement aspect in 2nd defrost operation pattern (beta) 2' of evaporator 8R is the same. Detailed description is omitted. Furthermore, P3 and P6 (third cooling operation pattern α3 as the defrosting return of the evaporator 8F and the evaporator 8R) in the table of FIG. 10 are the same operation mode.

  As described above, the refrigeration / refrigeration showcase 1 always has the first defrosting operation pattern β1 or the first defrosting operation pattern β1 ′ after the end of the first cooling operation pattern α1 having a high cooling capacity. Therefore, the growth of frost in the heat transfer tubes 15 and 15 of the evaporator 8F and the evaporator 8R is suppressed, and the cooling capacity of the evaporator 8F and the evaporator 8R due to frost formation on the heat transfer tubes 15 and 15 is maintained. Thus, the thermal efficiency of the refrigerated / refrigerated showcase 1 can be increased.

  In addition, since the operation pattern units U and U ′ are repeatedly performed in a predetermined period, the at least one evaporator 8F and 8R is always in the cooling operation, so the first defrosting operation patterns β1 and β1. 'Increased temperature inside the chamber can be suppressed. Furthermore, since the first cooling operation pattern α1 is performed for a longer time than the first defrosting operation patterns β1 and β1 ′, the rise in the internal temperature during the first defrosting operation patterns β1 and β1 ′ is the cooling capacity. The first cooling operation pattern α1 having a high value can be suppressed, and the return to the desired internal temperature can be performed in a short time.

  Further, in the first defrosting operation pattern β1, β1 ′, the heat of the refrigerant 16 is transferred from the inside of the heat transfer tube 15 to the outer surface of the heat transfer tube 15 by heat conduction, and thus on the outer surface of the heat transfer tubes 15, 15. Since it can be melted from the surface where the attached frost adheres, it takes more defrost than when using radiant heat from an external heat source such as a defrost heater or off-cycle using natural cooling or external cooling by blowing air. Since the amount of heat is small and frost melts in a short time and the defrosting efficiency is high, it is difficult to affect the internal temperature, and the thermal efficiency of the refrigerated / refrigerated showcase 1 can be increased.

  Further, by repeating the operation pattern units U and U ′ for a predetermined period, the second defrosting operation pattern β2 and β2 ′ in which the frost accumulated in the evaporator 8F and the evaporator 8R is performed at a predetermined timing for a long time, Since it can defrost reliably, the thermal efficiency of the freezing / refrigeration showcase 1 can be maintained in a high state. In addition, before the second defrosting operation pattern β2, β2 ′ is performed, the second cooling operation pattern α2 having a high cooling capacity is performed, and the second defrosting operation pattern β2, β2 ′ is performed. After that, since the third cooling operation pattern α3 having a high cooling capacity (continuous to the first cooling operation pattern α1 in the first operation pattern unit U in a predetermined period) is performed, the second defrosting operation pattern β2, The rise in the internal temperature at the time of β2 ′ can be minimized by the cooling operation pattern α (α2, α3) having a high cooling capacity, and the return to the desired internal temperature can be performed in a short time.

  Further, in the defrosting operation pattern β (the first defrosting operation pattern β1, β1 ′ and the second defrosting operation pattern β2, β2 ′), one of the evaporator 8F and the evaporator 8R is defrosted. When the operation is performed, the other is always performing the cooling operation. Therefore, the influence on the internal temperature due to the increase in the surface temperature of the heat transfer tube 15 during the defrosting operation pattern β is suppressed as much as possible, and the internal temperature is maintained. be able to. Further, as described above, when one of the evaporators is in the defrosting operation pattern β, the amount of the refrigerant 16 flowing into the other evaporator is increased, whereby the cooling capacity of the other evaporator is increased. Therefore, the influence on the internal temperature due to the increase in the surface temperature of the heat transfer tube 15 during the defrosting operation pattern β can be minimized.

  Further, a switching circuit 20 is provided downstream of the evaporator 8F and the evaporator 8R, and the evaporation pressure adjusting valve 26 of the switching circuit 20 is decompressed to a predetermined evaporation pressure via the expansion valves 17 and 17. Since the pressure of the refrigerant 16 is adjusted, the evaporation pressure of the refrigerant 16 in the evaporator 8F and the evaporator 8R can be stably and reliably adjusted. Further, since the members for adjusting the evaporation pressure of the refrigerant 16 in the evaporator 8F and the evaporator 8R are not concentrated upstream of the evaporator 8F and the evaporator 8R, the evaporator 8F and the evaporator 8F in the piping system C of the refrigeration cycle are not concentrated. The structure upstream of the evaporator 8R can be simplified.

  In addition, when the heat transfer tubes 15 and 15 and the first pipes 23 and 23 are communicated by switching the solenoid valves SV1 to SV4 of the switching circuit 20, the refrigerant 16 is kept in the heat transfer tubes 15 and 15 while the evaporation pressure of the refrigerant 16 is low. Since the evaporator 8F and the evaporator 8R can be set to the cooling operation pattern α and the switching circuit 20 is used, for example, it is not necessary to use a complicated adjustment valve or the like for automatically adjusting the opening degree. The switching circuit 20 using the evaporation pressure regulating valve 26 having a simple structure can increase the reliability of switching between the cooling operation pattern α and the defrosting operation pattern β of the evaporator 8F and the evaporator 8R.

  In addition, as described above, the operation modes of the evaporator 8F and the evaporator 8R (switching between the cooling operation pattern α and the defrosting operation pattern β) are electromagnetic valves SV1 to SV4 that operate according to a predetermined time table. This time table can be changed as appropriate. Therefore, if the time table is changed as appropriate, the evaporator 8F and the evaporator 8R are appropriately adjusted according to the frost formation state of the heat transfer tubes 15 and 15 that changes depending on the season, the in-store environment, and the surrounding environment of the refrigeration / refrigeration showcase 1. The operation mode can be switched, and the cooling capacity of the evaporator 8F and the evaporator 8R can be reliably maintained.

  In the above embodiment, the solenoid valves SV1 to SV4 are controlled to be switched at predetermined time intervals according to the time table. However, the present invention is not limited to this, and the evaporator 8F and the evaporator 8R are respectively connected to the defrosting operation pattern. When switching from β to the cooling operation pattern α, the surface temperature of the heat transfer tubes 15 and 15 is detected by a temperature sensor, and a control unit that switches the electromagnetic valves SV1 to SV4 based on the detection result is provided, for example, the heat transfer tube 15 , 15 when the surface temperature reaches a predetermined temperature, the controller switches the solenoid valves SV1 to SV4 so that the evaporator 8F and the evaporator 8R are switched from the defrosting operation pattern β to the cooling operation pattern α, respectively. Good. According to this, when the defrosting is completed, the defrosting operation pattern β can be efficiently switched to the cooling operation pattern α. In addition, the surface temperature of the heat transfer tubes 15 and 15 becomes 0 ° C., and the evaporator 8F and the evaporator 8R are switched from the defrosting operation pattern β to the cooling operation pattern α, respectively, after a predetermined time by the control unit. (So-called delay control) is also possible, and this can reliably prevent frost residue.

  Furthermore, when switching the evaporator 8F and the evaporator 8R from the first defrosting operation pattern β1, β1 ′ to the first cooling operation pattern α1 in the operation pattern units U, U ′, for example, the heat transfer tubes 15, 15 When the surface temperature of the heater reaches -1 ° C. (before reaching 0 ° C.), the controller switches the solenoid valves SV1 to SV4 so that the evaporator 8F and the evaporator 8R have the first defrosting operation patterns β1, β1 ′, respectively. May be switched to the first cooling operation pattern α1. According to this, it is possible to reliably prevent the internal temperature from being excessively increased by the first defrosting operation patterns β1 and β1 ′ when the operation pattern units U and U ′ are repeated for a predetermined period. The second cooling operation pattern α2 after the operation pattern units U and U 'are repeated for a predetermined period may be the same operation mode.

  Further, when the evaporator 8F and the evaporator 8R are switched from the cooling operation pattern α to the defrosting operation pattern β, the surface temperatures of the heat transfer tubes 15 and 15 are increased by a predetermined amount or more than the appropriate temperature in the cooling operation pattern α. Sometimes, the evaporator 8F and the evaporator 8R may be switched from the cooling operation pattern α to the defrosting operation pattern β by switching the electromagnetic valves SV1 to SV4. According to this, at the time when the cooling efficiency of the evaporator 8F and the evaporator 8R has decreased due to frost adhering, the cooling operation pattern α can be efficiently switched to the defrosting operation pattern β.

  The operation modes of the cooling operation pattern α and the defrosting operation pattern β of the evaporator 8F and the evaporator 8R can be freely changed. For example, the number of operation pattern units U and U 'in a predetermined period may be one time, or the operation pattern unit U may be performed after the operation pattern unit U' is performed first. Moreover, you may change the ratio of time (length) of 1st cooling operation pattern (alpha) 1 and 1st defrost operation pattern (beta) 1, (beta) 1 ', respectively.

  Further, after the end of the second defrosting operation pattern β2 (see P1 and P2 in the upper part of the table in FIG. 10), the third cooling operation pattern α3 (see P3 in the table of FIG. 10) as the defrosting return operation. ), The second defrosting operation pattern β2 ′ (see P4 and 5 in the table of FIG. 10) may be performed.

  Further, an evaporation pressure adjusting valve 26 may be provided between the evaporator 8F and the evaporator 8R and the expansion valves 17 and 17, and the evaporation pressure may be adjusted upstream of the evaporator 8F and the evaporator 8R.

  Moreover, you may provide the damper which interrupts | blocks the ventilation to the evaporator 8F and the evaporator 8R, respectively. According to this, the ventilation to the evaporator 8F and the evaporator 8R at the time of the defrosting operation pattern β is blocked by the damper, so that the air from the blower 9 is sent to the evaporator 8F and the evaporator 8R at the time of the defrosting operation pattern β. Since the defrosting of the evaporator 8F and the evaporator 8R can be performed under the condition of natural convection, the defrosting efficiency is increased.

  Next, a freezing / refrigerating showcase according to Embodiment 2 will be described with reference to FIG. The description of the same configuration as that shown in the above embodiment is omitted.

  As shown in FIG. 11A, switching circuits 200 and 200 are connected to the downstream side of the evaporator 8F and the evaporator 8R. The switching circuits 200 and 200 include first pipes 23 and 23 that communicate with the heat transfer pipes 15 and 15 of the evaporator 8F and the evaporator 8R, respectively, and second pipes that are bypass pipes provided in the first pipes 23 and 23, respectively. 24, 24, and three-way switching valves 25, 25 ′ are provided at the upstream intersections of the first pipes 23, 23 and the second pipes 24, 24.

  The switching circuits 200, 200 close the second pipes 24, 24, respectively, and connect the heat transfer pipes 15, 15 and the first pipes 23, 23 (see FIG. 11A), and the three-way switching valve 25. Closes the second pipe 24 and connects the heat transfer pipe 15 and the first pipe 23, and the three-way switching valve 25 ′ closes the first pipe 23 and connects the heat transfer pipe 15 and the second pipe 24. In the embodiment (see FIG. 11B), the three-way switching valve 25 closes the first pipe 23 and allows the heat transfer pipe 15 and the second pipe 24 to communicate, and the three-way switching valve 25 ′ connects the second pipe 24. It can be switched to a mode (not shown) in which the heat transfer tube 15 and the first pipe 23 are communicated with each other.

  According to this, since the evaporation pressures of the refrigerant 16 in the evaporator 8F and the evaporator 8R in the defrosting operation pattern can be controlled by the two evaporation pressure adjustment valves 26, 26, respectively, the evaporation pressure adjustment valves 26, 26 are opened. The defrosting ability of the evaporator 8F and the evaporator 8R can be adjusted by changing the set pressure. For example, even if the cooling operation pattern α is performed for the same time in the evaporator 8F and the evaporator 8R, when the amount of frost formation on the evaporator 8R is larger than that in the evaporator 8F, the evaporator 8R communicates with the heat transfer tube 15 of the evaporator 8R. By increasing the setting of the opening pressure of the evaporation pressure adjusting valve 26 provided in the second pipe 24, the evaporation pressure of the refrigerant 16 in the evaporator 8R is increased, and the evaporator 8F and the evaporator 8R having different frosting amounts are used. Defrosting operation patterns β (first defrosting operation patterns β1, β1 ′ and second defrosting operation patterns β2, β2 ′) of the same time make the frosting states of the evaporator 8F and the evaporator 8R substantially uniform. be able to.

  Next, a freezing / refrigerating showcase according to Embodiment 3 will be described with reference to FIG. The description of the same configuration as that shown in the above embodiment is omitted.

  As shown in FIG. 12, the evaporating pressure adjusting device is an electronic evaporating pressure adjusting valve 260, 260 disposed between the heat transfer tube 15 and piping 230, 230 disposed downstream thereof. The evaporation pressure adjusting valves 260 and 260 include a valve (not shown) that can adjust the opening degree of the flow path, and is connected to a control unit (not shown). In addition, the valve | bulb of this modification can be suitably adjusted now when the opening degree of a flow path is 10 to 100%.

  The controller sets the valve built in the evaporation pressure regulating valve 260 to 100% (maximum) during the cooling operation pattern α, and switches the valve when switching from the cooling operation pattern α to the defrosting operation pattern β. The opening degree is set to 100% to 10% (minimum), and the valve is operated so as to gradually expand from the opening degree of 10% until the defrosting operation pattern β is completed. According to this, in the state where a large amount of frost that remains on the outer surface of the heat transfer tube 15 remains, the temperature of the refrigerant 16 (evaporation pressure) is immediately increased with the valve opening degree of 10%, and thereafter As the frost melts, the temperature of the refrigerant 16 is adjusted to gradually decrease by increasing the degree of opening gradually. That is, since the temperature of the refrigerant 16 can be adjusted stepwise in accordance with the frosting condition on the outer surface of the heat transfer tube 15, defrosting can be performed efficiently while suppressing an increase in the internal temperature. The change in the degree of opening of the evaporation pressure adjusting valve 260 can be variously set according to the operating conditions of the evaporator 8F and the evaporator 8R. Further, the adjustable range of the degree of opening of the evaporation pressure adjusting valve 260 can be freely set. Furthermore, off-cycle defrosting is performed in which the flow of the refrigerant 16 is stopped by closing the flow path with the on-off valve 14 provided in the supply pipe 19 between the liquid receiver 18 and the expansion valves 17 and 17. You can also.

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

  Moreover, in the said Example, although the refrigerant | coolant temperature change means was demonstrated as the switching circuit 20 and switching circuit 200,200 as an evaporation pressure adjusting device, it is not restricted to this, For example, temperature differs in the piping system of a refrigerating cycle. A plurality of liquid receivers each containing the refrigerant may be provided and controlled by a switching valve or the like so that the refrigerant flows into the expansion valves 17 and 17 from the selected liquid receiver.

  In the above-described embodiment, the refrigeration / refrigeration showcase 1 displays the product in the refrigerated state. However, the decompression capacity of the expansion valves 17 and 17 and the set pressure of the evaporation pressure adjusting valves 26 and 26 are changed. Thus, the internal temperature may be changed to a temperature zone such as freezing or refrigeration close to room temperature.

  In the embodiment, the defrosting operation pattern β (first defrosting operation patterns β1, β1 ′ and second defrosting operation patterns β2, β2 ′) of the evaporator 8F and the evaporator 8R is the same set pressure. Although described as being performed, for example, the defrosting efficiency is increased by setting the set pressure of the second defrosting operation pattern β2, β2 ′ to a higher evaporation pressure than the first defrosting operation pattern β1, β1 ′. The second defrosting operation pattern β2, β2 ′ may be completed in a short time, and conversely, the set pressure of the first defrosting operation pattern β1, β1 ′ is set to the second defrosting operation pattern. By setting the evaporation pressure higher than β2 and β2 ′, the defrosting efficiency may be increased so that the second defrosting operation pattern β2 and β2 ′ can be completed in a shorter time. The defrosting ability of the evaporator 8F and the evaporator 8R increases as the evaporation pressure is higher and the defrosting time is longer. However, the higher the defrosting capacity, the greater the influence on the internal temperature in the defrosting operation pattern β. Therefore, it is preferable to set the evaporation pressure and the defrosting time in the defrosting operation pattern β of the evaporator 8F and the evaporator 8R in consideration of the influence on the internal temperature.

  Further, the second defrosting operation pattern β2, β2 ′ is a state in which the frost attached to the outer surface of the heat transfer tubes 15, 15 repeats the operation pattern units U, U ′ for a predetermined period (first defrosting operation pattern The second defrosting operation pattern β2, β2 ′ was performed in order to completely remove the frost, assuming that it remains in the state of defrosting by β1, β1 ′, but the operation pattern unit If frost can be completely removed while U and U ′ are repeated for a predetermined period, the second defrosting operation pattern β2 and β2 ′ may not be performed.

  In the second defrosting operation pattern β2, β2 ′, a heater or the like may be additionally used from the outside to shorten the time until defrosting is completed.

  Moreover, in the said Example, although the evaporator 8F and the evaporator 8R of the same structure were used, for example, the capacity | capacitance in a heat exchanger tube differs and you may use several evaporators from which cooling capacity differs. In addition, although two evaporators 8F and 8R are used, three or more evaporators may be used. Thus, as the number of evaporators increases, the internal temperature can be finely adjusted. It becomes possible.

  In the embodiment, the on-off valve 14 may not be provided in the supply pipe 19 between the liquid receiver 18 and the expansion valves 17 and 17.

1 Refrigerated showcase 8F, 8R Evaporator 14 On-off valve 15 Heat transfer tube 16 Refrigerant 17 Expansion valve 20 Switching circuit (evaporation pressure adjusting device)
25, 25 'Three-way selector valve 26 Evaporation pressure adjustment valve 230 Pipe 260 Evaporation pressure adjustment valve (evaporation pressure adjustment device / electronic evaporation pressure adjustment valve)
SV1 to SV4 Solenoid valve α Cooling operation pattern α1 First cooling operation pattern α2 Second cooling operation pattern α3 Third cooling operation pattern β, β ′ Defrosting operation pattern β1, β1 ′ First defrosting operation pattern β2 , Β2 ′ Second defrosting operation pattern U, U ′ operation pattern unit

Claims (5)

A refrigeration / refrigeration showcase using a refrigeration cycle equipped with an evaporator,
Equipped with a plurality of evaporators and an evaporation pressure adjusting device capable of adjusting the evaporation pressure of the refrigerant supplied into each evaporator,
A cooling operation pattern in which all the evaporators in the refrigeration cycle perform cooling;
A defrosting operation pattern in which at least one evaporator performs cooling after the cooling operation pattern ends, and at least one other evaporator is defrosted by increasing the evaporation pressure of the refrigerant by the evaporation pressure adjusting device; Have
The refrigeration / refrigeration showcase, wherein an operation pattern unit based on a combination of the cooling operation pattern and the defrosting operation pattern is repeatedly performed for a predetermined period.   The refrigeration / refrigeration showcase according to claim 1, wherein a plurality of the evaporators are sequentially defrosted in the defrosting operation pattern.   The refrigeration / refrigeration showcase according to claim 1 or 2, wherein the cooling operation pattern is performed for a longer time than the defrosting operation pattern.   A second cooling operation pattern in which cooling is performed in all the evaporators in the refrigeration cycle, and a second defrosting which is performed for a longer time than the defrosting operation pattern of the operation pattern unit after the end of the second cooling operation pattern. The refrigeration / refrigeration showcase according to any one of claims 1 to 3, wherein the operation pattern is performed after the operation pattern unit is repeated for a predetermined period.   The refrigeration / refrigeration according to any one of claims 1 to 4, wherein the evaporation pressure adjusting device is an electronic evaporation pressure adjusting valve capable of adjusting an evaporation pressure of a refrigerant supplied into the evaporator. Showcase.

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