JPH04270878A - Cold air circulation type open showcase - Google Patents

Abstract

PURPOSE:To prevent an excessive temperature-rise in a food receiving space by a method wherein an air speed sensor is installed in a ventilating passage for cold air curtain to start defrosting of a cooler when the air speed is reduced to a value lower than a predetermined value, in a cold air circulating type open showcase. CONSTITUTION:A cold air speed sensor 17 is installed in a ventilating passage 6 for cold air curtain and the output of the same is given to the subtractor 18 of a controller 21 consisting of an air speed setter 19, the subtractor 18 and a comparator 20. When the output of the cold air speed sensor 17 has become lower than a set value preset in the air speed setter 19, a control signal is outputted from the comparator 20 and defrosting operation is started.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention has an opening on the front surface, and the cool air flow blown out from the outlet facing the opening allows
This relates to a cold air circulation open showcase used for keeping food cold, in which an air curtain is formed in the opening and the storage space is cooled, and is particularly improved to properly start defrosting of the cooler. Regarding.

0002

2. Description of the Related Art A cold air circulation type open showcase of this type is shown in FIG. 4 and is known. In Figure 4,
The main case 1 has a substantially U-shaped cross section with an opening 1a on the front, and consists of an outer box 2 made of a heat insulating wall and an inner box 3 that forms a storage space 4 inside. A partition plate 5 is provided between the inner box 3 and the inner box 3 to form two layers of cold air curtain ventilation passage 6 and protection air curtain ventilation passage 7. The cold air curtain ventilation passage 6 has its upper and lower ends facing the opening 1a, and has an outlet 6a and an inlet 6b, respectively.
A fan 8 and a cooler 9 to which refrigerant is supplied from a refrigeration unit (not shown) via an expansion valve (not shown) are disposed inside. In addition, ventilation duct 7 for protective air curtain
has its upper and lower ends facing the opening 1a, and has an air outlet 7, respectively.
a and a suction port 7b, and a fan 10 is disposed inside. Reference numeral 11 represents an air conditioner attached to the air outlet 6a and the air outlet 7a, 12 represents a shelf that partitions the storage space 4 into upper and lower levels, and 13 represents a base.

[0003] In the aforementioned open showcase, a large number of products are displayed and stored in the storage space 4. Then, the air in the storage space is circulated through the cold air curtain ventilation path 6 as shown by the solid arrow by the fan 8 that rotates in the normal direction, and is cooled by the cooler 9 to become cold air and sent to the outlet 6a. This cold air is blown out from the outlet 6a to form a cold air curtain 14. In addition, by the fan 10 that rotates in the forward direction,
Uncooled air circulated through the protective air curtain ventilation path 7 as shown by solid arrows is blown out from the air outlet 7a to form a protective air curtain 15, which protects the cold air curtain 14 to enhance the heat shielding effect. Therefore, storage space 4
Products inside are efficiently cooled and kept cold.

[0004] During the cold storage operation, the cold air curtain 14 and the protective air curtain 15 draw in some outside air midway and flow into the suction ports 6b and 7b. Since this outside air has moisture, as the cold storage operation continues, the moisture contained in the outside air gradually forms frost on the surface of the cooler 9, and the cooling capacity of the cooler 9 decreases. For this reason, in the open showcase, a timer is used to perform a defrosting operation at appropriate intervals to remove the frost. During this defrosting operation, the operation of the refrigeration unit is stopped, the cooling of the cooler 9 is stopped, the fan 8 is operated in forward rotation, the fan 10 is operated in reverse rotation, and if necessary, the upstream side of the cooler 9 is The installed heater 16 is turned on. As shown by the chain arrow, the fan 10 sucks outside air, which is warmer than the air in the storage space, into the protective air curtain ventilation path 7 from the air outlet 7a. This outside air is sucked into the cold air curtain ventilation path 6 from the suction port 6b and flows as shown by the chain arrow. If necessary, the air is further heated by the heater 16 to become defrosting hot air, which washes and warms the cooler 9 to melt and remove the frost.

[0005]

[Problems to be Solved by the Invention] By the way, in conventional open showcases, the start of defrosting operation is performed according to a defrosting operation cycle determined by a timer, and furthermore, this defrosting operation cycle is different from that in an average environment. It is set according to the conditions. However, such a defrosting operation cycle does not always adequately respond to changing environmental conditions in open showcases that are operated throughout the year. For example, in the case of high temperature and high humidity conditions, the degree of frost formation on the cooler is high, so even though the amount of frost formation reaches its limit early and the cooling capacity begins to decline, defrosting operation may not continue until the scheduled time. Since it does not start, the temperature of the storage space increases. In addition, an increase in the amount of frost formation causes a decrease in the wind speed of the cold air circulating through the cold air curtain ventilation duct, reducing the effectiveness of the cold air curtain, which increases the amount of heat intrusion from the outside air into the storage space. The temperature of the space will rise. For example, in the case of low-temperature, low-humidity conditions, the degree of frost on the cooler is low, so even though the amount of frost is small, the defrosting operation is started at the scheduled time, so the melting of the frost is not completed. This results in excessive defrosting in which the defrosting operation is continued even when the defrosting operation is continued, and the temperature of the storage space increases in the latter half of the defrosting operation period. A rise in the temperature of the storage space increases the temperature of the products in the storage space, reducing the freshness of the products, so solving this problem has been an issue.

The present invention was developed in view of the problems of the prior art described above, and its purpose is to be able to start defrosting operation at a substantially constant amount of frost even if environmental conditions change, thereby reducing storage space. An object of the present invention is to provide an open showcase with cold air circulation that can prevent excessive temperature rise.

[0007]

[Means for Solving the Problems] The above-mentioned objects of the present invention are as follows:

1) A main body case with an approximately U-shaped cross section having an opening on the front and a storage space inside the opening, and a cold air curtain in the opening; A plurality of ventilation channels are provided inside the main body case to form a protective air curtain on the outside of the main body case, and the upper and lower ends thereof face the opening to form a blowout port and a suction port, respectively; In a cold air circulation type open showcase comprising a cooler and a fan disposed in a ventilation passage, and a fan disposed in the ventilation passage for a protective air curtain, the ventilation passage for a cold air curtain is provided with: The controller is equipped with a wind speed sensor and receives the output of the wind speed sensor and sends a signal to start defrosting the cooler when the output of the wind speed sensor decreases to an operating setting value, and

00
09) 2) In the means relating to the cold air circulation type open showcase described in item 1 above, the operating setting value is set by a wind speed setting device provided in the controller;

0010
3) In the means relating to the cold air circulation type open showcase described in item 1 above, this is achieved in that the operation setting value is an output value of a wind speed sensor attached to the ventilation path for the protective air curtain.

[0011]

[Operation] A wind speed sensor is installed in the ventilation path for the cold air curtain, and when the output of this wind speed sensor is received and the output of the wind speed sensor drops to the operating setting value, a control is sent to start defrosting the cooler. Even if environmental conditions change, once the frost on the cooler has grown to an appropriate level, the air volume in the cold air curtain ventilation duct will drop, and the output value of the wind speed sensor will be adjusted to the operating setting. When the temperature drops to , defrosting operation is started.

0012

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a configuration diagram of a cold air circulation type open showcase according to an embodiment of the present invention, in which (a) is a sectional view, and (b) is a cross-sectional view.
) is a control circuit diagram. Components that are the same as those in the conventional example shown in FIG. 4 are given the same reference numerals, and their explanations will be omitted. In Figure 1, 1
7 is an air outlet 6 as an example of the cold air curtain ventilation path 6.
This is a cold air wind speed sensor that detects the wind speed of cold air attached near a. 21 is a controller comprising, for example, a subtracter 18, a wind speed setting device 19, and a comparator 20. The output of the cold air wind speed sensor 17 is given to the subtractor 18 and the wind speed setting device 1
It is subtracted from the output of 9. The result of subtraction by the subtractor 18 is given to the comparator 20, but if the wind speed of cold air is high and the output of the cold air wind speed sensor 17 is larger than the output of the wind speed setting device 19, the result of subtraction by the subtractor 18 is correct. Comparator 20 next door
No control signal output is generated. In addition, the wind speed of cold air decreases, and the output of the cold air wind speed sensor 17 changes to the wind speed setting device 1.
9, the subtraction result in the subtracter 18 becomes negative and a control signal is output from the comparator 20. When the control signal output occurs, the switch 22a for the refrigeration unit 22 that supplies refrigerant to the cooler 9 of the open showcase is opened and the cooling of the cooler 9 is stopped. The switching switch 10a for the fan 10 disposed in the protective air curtain ventilation path 7 is switched by
0 is reversed, and furthermore, if necessary, the switch 16a connected in series to the installed heater 16 is closed to start heating the heater 16, and defrosting is started. Note that once defrosting has started, the output of the control signal is
The output is maintained as it is until the defrosting is completed, regardless of the output of the cold air wind speed sensor 17. In addition, the wind speed setting device 19
It is preferable to set the set value to this wind speed because when the wind speed of cold air decreases to a certain wind speed or less, the temperature of the storage space increases significantly. Furthermore, even if the environmental conditions change, the amount of frost formed at the time of starting the defrosting operation can be kept almost constant, so that the defrosting operation can be canceled in the same way as in the prior art. That is, a timer may be used, or it may be detected that the cooler 9 or the storage space has reached a predetermined temperature.

Next, different embodiments of the present invention will be explained. FIG. 2 is a configuration diagram of a cold air circulation type open showcase according to a different embodiment of the present invention, in which (a) is a sectional view, and (b) is a cross-sectional view.
) is a control circuit diagram. The same parts as those in the embodiment of the present invention shown in FIG. 1 and the conventional example shown in FIG. In FIG. 2, reference numeral 23 denotes a protective air wind speed sensor that is installed near the outlet 7a as an example of the protective air curtain ventilation path 7 and detects the wind speed of the protective air. 25 is a controller consisting of, for example, a subtracter 18 and a comparator 20. The output of the protective air wind speed sensor 23 is given to a subtractor 18 and subtracted from the output of the cold air wind speed sensor 17. The subtraction result in the subtracter 18 is given to the comparator 20, but if the wind speed of cold air is high and the output of the cold air wind speed sensor 17 is larger than the output of the protective air wind speed sensor 23, the subtracter 1 is sent to the comparator 20.
The result of the subtraction at 8 is positive and no control signal is output from the comparator 20. In addition, when the wind speed of cold air becomes small and the output of the cold air wind speed sensor 17 becomes equal to or lower than the output of the protective air wind speed sensor 23, the subtractor 18
The subtraction result at is negative and a control signal output from the comparator 20 is generated. When the control signal output occurs, the switch 22a for the refrigeration unit 22 that supplies refrigerant to the cooler 9 of the open showcase is opened and the cooling of the cooler 9 is stopped. The changeover switch 10a for the fan 10 disposed in the protective air curtain ventilation path 7 is switched, the fan 10 is reversed, and furthermore, if necessary, it is connected in series to the heater 16 installed. The switch 16a is closed, heating of the heater 16 is started, and defrosting is started. In this case as well, once defrosting is started, the control signal output is maintained as is until defrosting is completed, regardless of the output of the cold air wind speed sensor 17.

FIG. 3 shows a comparison between the main points (ventilation passage wind speed, storage space temperature, and amount of frost formation) during cold storage operation and defrosting operation in this different embodiment with the conventional example. In addition, a graph of changes over elapsed time is shown in a case where the environmental conditions are high temperature and high humidity and the cooler 9 is excessively frosted. In all the main graphs, the vertical axis shows each amount, the horizontal axis shows elapsed time, the solid line shows the case of the conventional example, and the dotted line shows the case of this different embodiment. In the graph of ventilation duct wind speed,
When cold storage operation is started after the previous defrosting is completed, the wind speed of the protective air remains constant over time, but the wind speed of the cold air gradually increases as frost builds up on the cooler 9, as shown in the frost amount graph. It gradually decreases. When frost formation becomes excessive, the wind speed of the cold air becomes lower than the wind speed of the protective air. At this stage, the operation is switched to defrosting operation, and as the frost melts, the wind speed of the cold air is restored again. In the graph of the storage space temperature, when the cold storage operation is started after the previous defrosting is completed, the storage space temperature drops once and hardly rises as long as there is little frost on the cooler 9. However, when the wind speed of the cold air becomes lower than the wind speed of the protective air, the temperature of the storage space begins to rise significantly. For this reason, the temperature of the storage space exceeds a temperature at which there is a possibility that the freshness of the product may decrease. At this stage, the defrosting operation is finally switched to, and the storage space temperature continues to rise until the defrosting operation is completed. By the way, in the case of a different embodiment of the present invention, the cold air wind speed sensor 17 and the protective air wind speed sensor 23 are installed, and as described above, when the wind speed of the cold air becomes lower than the wind speed of the protective air, the defrosting is performed. I started driving. For this reason, defrosting is started when the storage space temperature is still sufficiently low, so even when the defrosting operation is complete, the storage space temperature is at a temperature that may cause the product to lose its freshness. It will never be surpassed. In this case as well, even if the environmental conditions change, the amount of frost formed at the start of the defrosting operation can be kept approximately constant, so the defrosting operation can be canceled in the same manner as in the prior art. That is, a timer may be used, or it may be detected that the cooler 9 or the storage space has reached a predetermined temperature.

In the above description, it was assumed that the fan 10 disposed in the protective air curtain ventilation path 7 is reversed during the defrosting operation, but it may continue to rotate in the forward direction or stop again; in the former case. In the latter case, the switching switch 10a is not required, and in the latter case, a switch that is opened during the defrosting operation is used instead of the switching switch 10a. Furthermore, although the heater 16 is used during the defrosting operation, the heater 16 is not necessarily used, and the switch 16a is not necessary in this case. In addition, although the cold air wind speed sensor 17 and the protective air wind speed sensor 23 are installed near the outlet, they may be installed anywhere within the ventilation path, in short, the outlet 6a and the outlet 7.
It is sufficient if the outputs of the cold air wind speed sensor 17 and the protective air wind speed sensor 23 are the same when the cold air wind speed and the protective air wind speed near a are the same. Furthermore, although the controller includes the subtracter 18 and the comparator 20, it is not necessary to include the subtracter if a comparator having the same function as the above-described subtracter is used.

[0016]

Effects of the Invention: A wind speed sensor is installed in the ventilation path for the cold air curtain, and upon receiving the output of the wind speed sensor, a signal is sent to start defrosting the cooler when the output of the wind speed sensor drops to the operating setting value. As a result, when the frost on the cooler grows to an appropriate level, the air volume in the cold air curtain ventilation path decreases, and the output value of the wind speed sensor decreases to the operating setting value, allowing defrosting. Since the operation is started, the defrosting operation can be started at a substantially constant amount of frost even if the environmental conditions change. Therefore, defrosting is started when the storage space temperature is still sufficiently low, so even when the defrosting operation is complete, the storage space temperature will not exceed the temperature at which the freshness of the product will decrease. ,
This has the effect of not causing the problem of deterioration of product freshness.

[Brief explanation of the drawing]

[Fig. 1] A configuration diagram of a cold air circulation type open showcase according to an embodiment of the present invention.

[Fig. 2] A configuration diagram of a cold air circulation type open showcase according to a different embodiment of the present invention.

[Figure 3] Graph showing changes in main points over time

[Figure 4] Cross-sectional view of a conventional cold air circulation type open showcase

[Explanation of symbols]

6. Ventilation duct for cold air curtain 7 Ventilation duct for protective air curtain 17 Cold air wind speed sensor 18 Subtractor 19 Wind speed setting device 20 Comparator 21 Controller 22 Protective air wind speed sensor 24 Controller

Claims (3)

[Claims] 1. A main body case having an opening on the front and a storage space inside the opening and having a substantially U-shaped cross section; a cold air curtain provided in the opening; A plurality of ventilation channels are provided inside the main body case to form a protective air curtain on the outside of the main body case, and the upper and lower ends thereof face the opening to form a blowout port and a suction port, respectively; In a cold air circulation type open showcase comprising a cooler and a fan disposed in a ventilation passage, and a fan disposed in the ventilation passage for a protective air curtain, the ventilation passage for a cold air curtain is provided with: It is characterized by being equipped with a wind speed sensor and a controller that receives the output of the wind speed sensor and sends a signal to start defrosting the cooler when the output of the wind speed sensor decreases to an operating setting value. Open showcase with cold air circulation. 2. The cold air circulation type open showcase according to claim 1, wherein the operating setting value is set by a wind speed setting device provided in the controller. 3. The cold air circulation type open showcase according to claim 1, wherein the operation setting value is an output value of a wind speed sensor attached to a protective air curtain ventilation path. .