JPH1194442A - Low-temperature showcase - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low-temperature showcase, contriving the unification of frosting of a cooler and elongating the interval of defrosting. SOLUTION: A low-temperature showcase is provided with a plurality of coolers 11, 13, arranged in series in the cooling duct 7 of a showcase main body 1, and defrosting means 71, 73, defrosting respective coolers 11, 13. The plurality of coolers 11, 13, arranged in series, are provided respectively with returning temperature detecting sensors 31, 33, detecting returning temperature from defrosting operation effected by the defrosting means 71, 73 while the set temperature of the returning temperature detecting sensor 33 for the downstream side cooler 13 is set so as to be lower than that of the returning temperature detecting sensor 31 for the upstream side cooler 11 whereby the defrosting operation of the downstream side cooler 13 is finished earlier than that of the upstream side cooler 11 to return to the cooling operation earlier than the same operation in the upstream side cooler 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low-temperature showcase, and more particularly, to a technique for suppressing frost formation on a cooler.

[0002]

2. Description of the Related Art In recent years, various foods such as frozen meat and ice cream, as well as meat and fresh fish, are sold in large-scale retail stores such as supermarkets. These foods are stored and displayed in refrigerated or frozen showcases (hereinafter collectively referred to as low-temperature showcases) so that customers can easily take them while controlling the temperature appropriately.

The low-temperature showcase includes a showcase main body in which food is stored and a refrigerator including a compressor, a decompression device, a condenser, a cooler, and the like. Thus, cool air is supplied.

[0004] In this type of low-temperature showcase, frost may form on the cooler of the refrigerator during operation. Therefore, a defrosting operation using a hot gas or a defrosting heater is performed, but there is a demand from users that they do not want to perform the defrosting operation as much as possible when a supermarket or the like is opened. In order to meet this demand, the size of the cooler is increased and the defrost interval is made as long as possible.

[0005]

However, in the conventional configuration, even if the defrost interval can be lengthened, there is a problem that the operation time required for the defrost operation becomes longer as the size of the cooler increases. is there. Therefore, for example, it has been proposed to divide a large-sized cooler into two parts and to attach a defrosting means such as a defrost heater to each of the two divided coolers to shorten the defrosting operation time. However, when two coolers are vertically arranged in series in a cooling duct extending in the vertical direction, for example, frost or ice of the downstream cooler falls on the upstream cooler, and the defrost time of the upstream cooler is reduced. Is longer.

In order to lengthen the defrost interval,
A fin pitch on the upstream side of the cooler is roughly formed. However, in the conventional configuration, the liquid refrigerant is introduced to the downstream side of the cool air of the cooler, and sequentially flows to the upstream side,
Since the cooler is configured to be drawn out from the upstream side of the cool air, there is a problem that frost is formed on the most upstream side of the narrow fin pitch of the cooler and the cooling capacity is reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a low-temperature showcase in which frost formation on a plurality of coolers can be made uniform and a defrosting operation interval can be lengthened. Aim.

[0008]

According to the first aspect of the present invention, a plurality of coolers are arranged in series in a cooling duct of a showcase body, and each cooler is defrosted. In a low-temperature showcase provided with defrost means, the plurality of coolers arranged in series are provided with return temperature detection sensors for detecting a return temperature from the defrost operation by the defrost means, respectively, and the downstream cooler is provided. , The set temperature of the return temperature detection sensor is set lower than the set temperature of the return temperature detection sensor of the upstream-side cooler.

According to a second aspect of the present invention, there is provided a low-temperature showcase comprising a plurality of coolers arranged in series in a cooling duct of a showcase main body and provided with defrosting means for defrosting each cooler. A main return temperature detection sensor for detecting a return temperature of the upstream cooler from the defrosting operation by the defrosting means is provided near the air outlet in the inside, and the downstream cooling by the defrosting means is provided near the outlet of the downstream cooler. An auxiliary return temperature detection sensor for detecting a return temperature from the defrosting operation of the vessel is provided.

According to a third aspect of the present invention, in the low-temperature showcase, a plurality of coolers are arranged in series in a cooling duct of the showcase main body, and defrosting means for defrosting each cooler is provided. A return temperature detection sensor for detecting a return temperature of the downstream cooler from the defrosting operation by the defrost means is provided therein, and a delay timer for measuring a predetermined time from the return of the downstream cooler is provided. The upstream cooler is returned from the defrosting operation at the time counted according to the above.

According to a fourth aspect of the present invention, in any one of the first to third aspects, the defrosting means is a defrost heater.

In these inventions, since the defrosting operation of the downstream cooler is completed earlier than the defrosting operation of the upstream cooler, the cooling operation can be performed using the downstream cooler after the defrosting operation is completed. , And the defrosting operation time is shortened.

As a result, since the defrosting operation time of the upstream cooler is kept long, even if a relatively large amount of frost and ice melts and falls from the downstream cooler to the upstream cooler, The upstream-side cooler can be almost certainly defrosted.

According to a fifth aspect of the present invention, in a low-temperature showcase in which a plurality of coolers are arranged in series in a cooling duct of a showcase body, the fin pitch of the upstream cooler is formed to be coarser than the fin pitch of the downstream cooler. In addition, the liquid refrigerant is introduced upstream of the upstream cooler, introduced from the downstream side to the downstream side of the downstream cooler, and discharged from the upstream side.

According to the present invention, the warmed refrigerant after passing through the upstream cooler and the downstream cooler is discharged from the upstream of the downstream cooler. Since the fin surface temperature rises, frost formation on this portion is suppressed, and the defrost interval can be lengthened.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Some embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a longitudinal sectional view of a refrigerated showcase according to a first embodiment of the present invention. The refrigerated showcase 1 of the present embodiment is a multi-stage open type having an open front surface and a separate type in which a liquid refrigerant is supplied from a cooling unit installed outdoors. The showcase body 3 has four stages of display shelves 5 at its opening, and an inner layer air curtain (the flow is indicated by an arrow in the A direction) and an outer layer air curtain (the flow Is indicated by an arrow in the B direction).

A cooling duct 7 is formed in the showcase body 3 so as to surround the display shelf 5.
A cooler blower 9 is arranged in the lower part, and an upstream cooler 11 and a downstream cooler 13 are arranged in order from the bottom in the vertical part. The cooling air circulating means is provided by these, the cool air inlet 15 and the cool air outlet 17. Is configured.

A blow duct 21 is formed in the showcase body 3 so as to surround the cooling duct 7.
An air curtain blower (not shown) is provided therein, and an air curtain generating means is constituted by the air curtain blower, the air inlet 23 and the air outlet 25. In the figure, reference numeral 31 denotes a first outlet side temperature sensor (return temperature detection sensor) for detecting the outlet side temperature of the upstream side cooler 11, and reference numeral 33 denotes a second outlet side for detecting the outlet side temperature of the downstream side cooler 13. It is a temperature sensor (recovery temperature detection sensor). The upstream cooler 1
1 is formed so that the cooling fin pitch thereof is coarser than the cooling fin pitch of the downstream side cooler 13.

In the case of the present embodiment, the cool air around the display shelf 5 is sucked into the cooling duct 7 from the cool air inlet 15 by the cooler blower 9 and then passes through the coolers 11 and 13 to a predetermined temperature. And is blown out from the cool air outlet 17 toward the display shelf 5. The air that generates the air curtain is supplied to the air inlet 2 by the air curtain blower.
After the air is sucked into the air duct 21 from the air outlet 3, the air is blown out from the air outlet 25 toward the air inlet 23.

FIG. 2 is a schematic configuration diagram showing the refrigeration cycle of the first embodiment and its control system. As shown in the figure, the refrigerating cycle includes two cooling units 11 and 13 on the side of the refrigerated showcase 1 and first and second electric expansion valves 37 and 39 provided corresponding thereto, and a cooling unit 41. , A compressor 43, a condenser 45, a liquid receiver 47, and the like.
In the drawing, reference numeral 49 denotes a blower for a condenser installed in the cooling unit 41, and reference numerals 51 to 58 denote refrigerant pipes used for flowing a liquid refrigerant or a gas refrigerant. Reference numeral 100 constitutes defrosting means. The hot gas from the compressor 43 bypasses the condenser 45 and is led directly to the coolers 11 and 13, and the hot gas removes frost adhering to the coolers 11 and 13. Reference numerals 81 and 83 denote electric expansion valves for defrosting.

In the refrigerated showcase 1, a showcase-side control unit (hereinafter, referred to as a drive unit) for driving and controlling the cooler blower 9, the first and second electric expansion valves 37 and 39, the defrost electric expansion valves 81 and 83, and the like. ECU 61) is provided. The showcase-side ECU 61 includes a CPU,
It comprises an input / output interface, a ROM, a RAM, a timer counter, and the like. The input interface is connected to various sensors including the first and second outlet-side temperature sensors 31, 33.

On the other hand, in the cooling unit 41, the compressor 4
A cooling unit-side ECU 63 that drives and controls the blower 3 and the condenser blower 49 is provided. Cooling unit side ECU
63 is a CPU, an input / output interface and an RO
M, RAM, timer counter and the like. Also, the showcase-side ECU 61 and the cooling unit-side ECU
63 is connected by a communication line 65, and mutually exchanges signals.

The operation of the first embodiment will be described below. When the refrigerated showcase 1 is connected to the cooling unit 41 and the operation of the refrigeration cycle is started, as shown in FIG.
The pressure is sucked into the compressor 43 through 8. The gas refrigerant is compressed in the compressor 43 to have a high temperature and a high pressure, and then flows into the condenser 45 through the refrigerant pipe 51, and is condensed and liquefied while flowing through the condenser 45. Then, some of the liquid refrigerant
The refrigerant is diverted from the refrigerant pipe 52 to the refrigerant pipe 53, and the refrigerant pipe 53
The pressure is reduced by the first motor-operated expansion valve 37 interposed in the upstream side, and flows into the upstream-side cooler 11. The remainder of the liquid refrigerant is diverted from the refrigerant pipe 52 to the refrigerant pipe 55, decompressed by the second electric expansion valve 39 interposed in the refrigerant pipe 55, and flows into the downstream cooler 13. The liquid refrigerant evaporates and evaporates in the two coolers 11 and 13, returns to the receiver 47 via the refrigerant pipes 54, 56 and 57, is stored in the receiver 47, and then returns to the refrigerant pipe 58. Is sucked into the compressor 43 through the compressor.

The two coolers 11, 13 have their surface temperatures below freezing due to the latent heat of vaporization accompanying the vaporization of the liquid refrigerant, and cool the air passing between the cooling fins. The cooled air is blown into the showcase body 3 by the blower 9 for the cooler.
Circulates as indicated by the arrow (FIG. 1), and cools the products displayed on the display shelf 5 to a predetermined temperature.

When the cooling operation is continued, frost adheres to both the coolers 11 and 13, so that the defrosting operation is performed at appropriate intervals. In this defrosting operation, referring to FIG. 2, by opening the first and second electric expansion valves 37 and 39 and opening the electric expansion valves 81 and 83 for defrost, hot gas is supplied as indicated by the dotted arrow. It is carried away.

In this embodiment, the defrosting operation by the defrosting means 100 is stopped according to the output from the return temperature detecting sensors 31 and 33. The set temperature of the return temperature detection sensor 33 of the downstream cooler 13 is set lower than the set temperature of the return temperature detection sensor 31 of the upstream cooler 11, whereby the defrosting operation of the downstream cooler 13 is performed. Then, the return is performed earlier than the defrosting operation of the upstream-side cooler 11. That is, the set temperature TS2 of the downstream cooler 13 is set lower than the set temperature TS1 of the upstream cooler 11 by a predetermined value (for example, 3 ° C.). The temperature of the side cooler 13 reaches the set temperature TS2 earlier. Then, the showcase-side ECU 61 receives the signal from the return temperature detection sensor 33 and receives the signal from the defrost electric expansion valve 8.
3 and the second electric expansion valve 39 is opened. According to this, the defrosting operation of the downstream cooler 13 ends early, and at the same time, the downstream cooler 13 returns to the cooling operation.

Since the set temperature Ts1 of the upstream cooler 11 is higher by a predetermined value (for example, 3 ° C.), the hot gas is supplied by the defrosting means 100 until the set temperature is reached. Then, when the temperature reaches the set temperature, the defrosting operation is terminated later than the downstream cooler 13. In this case, the showcase-side ECU 61 receives the signal from the return temperature detection sensor 31, closes the electric expansion valve for defrost 81, and opens the first electric expansion valve 37. According to this, all the defrosting operations are completed and the operation returns to the cooling operation.

According to this, since the defrosting operation time of the upstream cooler 11 is kept long, it is assumed that a relatively large amount of frost and ice melts and falls from the downstream cooler 13 to the upstream cooler 11. Also, the defrosting of the upstream-side cooler 11 can be performed almost certainly.

FIG. 3 is a longitudinal sectional view of a refrigerated showcase according to a second embodiment of the present invention, and FIG. 4 is a schematic configuration diagram showing a refrigeration cycle and a control system thereof. As shown in these figures, the refrigerated showcase 1 of the second embodiment is also
The overall configuration is substantially the same as that of the first embodiment, except that the defrosting means by hot gas is omitted, and the two coolers 1
Defrost heaters 71 and 7, which are energized and controlled by the showcase-side ECU 61, are provided below (upstream) of the heaters 1 and 13, respectively.
3 is attached.

The operation of the second embodiment will be described below.

In the case of this embodiment, the first and second outlet side temperature sensors 31 and 33 are used for controlling the temperature of both the coolers 11 and 13 during the normal operation, as in the first embodiment. In the event of frost, it functions as a return temperature detection sensor. When the refrigerated showcase 1 is operated for a predetermined time, the showcase-side ECU 61 starts defrosting the coolers 11 and 13 based on the value of a built-in timer. During this defrosting operation, the operation of the compressor 43 is stopped, and the defrosting heater 71,
73 is energized.

In the case of this embodiment, the return temperature differs between the two coolers 11 and 13. That is, the downstream cooler 1
3 is set lower than the return temperature TR1 of the upstream-side cooler 11 by a predetermined value (for example, 3 ° C.). Therefore, the temperature of the downstream-side cooler 13 reaches the return temperature TR2 earlier by energizing the defrost heaters 71 and 73. Then, the showcase-side ECU 61 sets the return temperature detection sensor 3
Upon receiving the signal from 3, the power supply to the defrost heater 73 is cut off, and at the same time, the compressor 43 is driven to close the first electric expansion valve 37 and open the second electric expansion valve 39. According to this, the defrosting operation of the downstream cooler 13 ends early, and at the same time as the end, the downstream cooler 13 returns to the cooling operation.

Since the return temperature TR1 of the upstream cooler 11 is higher by a predetermined value (for example, 3 ° C.), the power supply to the defrost heater 71 is continued until the return temperature TR1 is reached. And
When the temperature reaches the return temperature, the defrosting operation is terminated later than the downstream cooler 13. In this case, the showcase ECU
61 receives a signal from the return temperature detection sensor 31 and cuts off the power supply to the defrost heater 71, and at the same time, the first electric expansion valve 3
Open 7. According to this, all the defrosting operations are completed and the operation returns to the cooling operation.

According to this, since the defrosting operation time of the upstream cooler 11 is kept long, it is assumed that a relatively large amount of frost and ice melts and falls from the downstream cooler 13 to the upstream cooler 11. Also, the defrosting of the upstream-side cooler 11 can be performed almost certainly.

FIG. 5 is a longitudinal sectional view of a refrigerated showcase according to a third embodiment of the present invention. As shown in this figure, the refrigerated showcase 1 of the third embodiment has substantially the same overall configuration as that of the refrigerated showcase 1 of the second embodiment. Not attached,
An outlet temperature sensor (main return temperature detection sensor) 81 is disposed near the cool air outlet 17 in the cooling duct 7, and an auxiliary return temperature detection sensor 83 is disposed downstream of the downstream cooler 13. The temperature sensors 81 and 83 are connected to an input interface of the showcase-side ECU 61.

The operation of the third embodiment will be described below.

In the case of this embodiment, the main return temperature detection sensor 81 is used for controlling the temperature of both the coolers 11 and 13 during the normal operation. As described above, when the refrigerated showcase 1 is operated for a predetermined time, the showcase E
The CU 61 starts the defrosting of both the coolers 11 and 13 and stops the operation of the compressor 43, and at the same time, the defrosting heaters 71 and 7
3 is energized. Then, the showcase-side ECU 61
When the downstream temperature of the downstream cooler 13 detected by the auxiliary return temperature detection sensor 83 reaches a predetermined value, the downstream cooler 13 is returned from defrost to normal operation. Next, when the temperature detected by the main return temperature detection sensor 81 reaches a predetermined value, the upstream cooler 11 is returned from defrost to normal operation. In this embodiment, the auxiliary return temperature detection sensor 83
Is set lower than the set temperature of the main return temperature detection sensor 81. As described above, the control can be performed by detecting the temperature of the air flowing through the cooling duct 7 without using the sensors for detecting the temperatures of the coolers 11 and 13.

Next, a fourth embodiment will be described. However, since the configuration is the same as that of the third embodiment, illustration is omitted. In the fourth embodiment, a delay timer (not shown) is provided in the showcase-side ECU 61, and when a predetermined time elapses after the downstream cooler 13 returns from the defrost to the normal operation, the upstream cooler 13 is provided. 11 is also configured to return from defrosting to normal operation. As a result, similarly to the third embodiment, defrosting is performed for a longer time in the upstream cooler 11 than in the downstream cooler 13, so that a relatively large amount of frost adhered to the inlet cooling fins. Ice and ice also reliably melt and fall, so that the cooling air flows smoothly.

FIG. 6 is a longitudinal sectional view of a refrigerated showcase according to a fifth embodiment of the present invention, and FIG. 7 is a front view of a cooler. As shown in these figures, in the refrigerated showcase 1 of the fifth embodiment, a single cooler 91 is provided in a vertical portion of the cooling duct 7. The cooler 91 is divided into an upstream cooler 93 and a downstream cooler 95, and the fin pitch of the upstream cooler 93 is formed larger than the fin pitch of the downstream cooler 95. Also, the refrigerant pipe 9
The refrigerant by 7 is introduced into the upstream side 93a of the upstream side cooler 93, is introduced from the downstream side 93b to the downstream side 95a of the downstream side cooler 95, and is discharged from the upstream side 95b.

According to the configuration of FIG. 7, it is general that the most frost adheres to the upstream side of the downstream cooler 95 where the fin pitch becomes narrow. If frost adheres to this portion, it will block the air flow path. In this embodiment, as shown in FIG. 7, an upstream cooler 93 and a downstream cooler 95 are provided on the upstream side of the downstream cooler 95 to which frost is most likely to adhere.
Is passed through the refrigerant pipe 97, so that the surface temperature of the fin in this portion rises.
Therefore, frost formation on this portion is suppressed, and the defrost interval can be lengthened.

The description of the specific embodiment is completed above.
Aspects of the present invention are not limited to this embodiment.
For example, in each of the above embodiments, the present invention is applied to a multi-stage open type refrigerated showcase, but may be applied to a refrigerated or frozen showcase having a glass door or the like. In the second to fourth embodiments, the defrost heater is used as the defrost means. However, a method such as supplying hot gas to a cooler may be adopted. In addition, the specific configuration of the low-temperature showcase, the arrangement of the temperature sensors, and the like can be appropriately changed without departing from the gist of the present invention.

[0043]

According to the present invention, since the defrosting operation of the downstream cooler is completed earlier than the defrosting operation of the upstream cooler, the downstream cooler returned from the defrosting operation is used. Cooling operation is possible, shortening the defrosting operation time, and keeping the defrosting operation time of the upstream cooler long, so that a relatively large amount of frost and ice is removed from the downstream cooler on the upstream side. Even if it melts and falls on the cooler, the upstream cooler can be almost completely defrosted.

According to the fifth aspect of the present invention, the warmed refrigerant that has passed through the upstream cooler and the downstream cooler is discharged from the upstream side of the downstream cooler. Since the surface temperature of the fin on the most upstream side rises, frost formation on this portion is suppressed, and effects such as a longer defrost interval can be obtained.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a refrigerated showcase according to a first embodiment of the present invention.

FIG. 2 is a schematic configuration diagram illustrating a refrigeration cycle and a control system according to the first embodiment.

FIG. 3 is a longitudinal sectional view of a refrigerated showcase according to a second embodiment of the present invention.

FIG. 4 is a schematic configuration diagram illustrating a refrigeration cycle and a control system according to a second embodiment.

FIG. 5 is a longitudinal sectional view of a refrigerated showcase according to third and fourth embodiments of the present invention.

FIG. 6 is a longitudinal sectional view of a refrigerated showcase according to a fifth embodiment of the present invention.

FIG. 7 is a front view of a cooler according to a fifth embodiment.

[Description of Signs] 1 Refrigerated showcase 3 Showcase main body 7 Cooling duct 9 Cooler blower 11 Upstream cooler 13 Downstream cooler 31, 33 Return temperature detection sensor 61 Showcase side ECU 71, 73 Defrost heater 81 Main Return temperature detection sensor 83 Auxiliary return temperature detection sensor

Claims (5)

[Claims] 1. A low-temperature showcase comprising a plurality of coolers arranged in series in a cooling duct of a showcase main body and a defrosting means for defrosting each cooler, wherein the plurality of cooling units arranged in series are provided. The dehumidifier is provided with a return temperature detection sensor for detecting the return temperature from the defrosting operation by the defrosting means, and sets the set temperature of the return temperature detection sensor of the downstream cooler to the return temperature detection sensor of the upstream cooler. A low-temperature showcase characterized by being set lower than the set temperature. 2. A low-temperature showcase comprising a plurality of coolers arranged in series in a cooling duct of a showcase main body and provided with a defrosting means for defrosting each cooler. A main return temperature detection sensor for detecting a return temperature from the defrosting operation of the upstream cooler by the defrosting means is provided, and the defrosting operation of the downstream cooler by the defrosting means is provided near the outlet of the downstream cooler. A low-temperature showcase, comprising an auxiliary return temperature detection sensor for detecting the return temperature of the vehicle. 3. A low-temperature showcase comprising a plurality of coolers arranged in series in a cooling duct of a showcase main body and provided with defrosting means for defrosting each cooler, wherein the defrosting means is provided in the cooling duct. Provided a return temperature detection sensor for detecting a return temperature of the downstream cooler from the defrosting operation, and a delay timer for measuring a predetermined time from the return of the downstream cooler. A low-temperature showcase characterized by returning an upstream cooler from a defrosting operation. 4. The low-temperature showcase according to claim 1, wherein the defrosting means is a defrost heater. 5. A low-temperature showcase in which a plurality of coolers are arranged in series in a cooling duct of a showcase body, wherein a fin pitch of an upstream cooler is formed to be coarser than a fin pitch of a downstream cooler, and a liquid refrigerant is provided. A low-temperature showcase, wherein the low-temperature showcase is configured to be introduced into the upstream side of the upstream cooler, to be introduced from the downstream side to the downstream side of the downstream cooler, and to be led out from the upstream side.