JPS63290381A - Operation controller for open showcase - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Industrial application field]

The present invention is equipped with two sets of evaporators that are supplied with refrigerant in circulation from a common compressor, and in the simultaneous cooling mode, these two evaporators perform the cooling operation, and in the defrosting mode, one set of evaporators performs the cooling operation. An open showcase (i.e., a device in which products are kept cool and displayed in a cabinet with an opening to take products in and out) while the other set of evaporators performs defrosting action. ) operation control device, in particular, the period of one operation cycle including the simultaneous cooling mode and the defrosting mode or the time of the simultaneous cooling mode is automatically and variably set according to the time required for defrosting. The present invention relates to an operation control device. Note that in the following figures, the same reference numerals indicate the same or corresponding parts.

[Conventional technology]

During cooling operation, water vapor in the air forms frost on the evaporator (also called cooler) of this type of open showcase, reducing its cooling capacity, so defrost the evaporator at regular intervals. need to be done. For defrosting, a method is usually used in which a heater or the like is used to heat the circulating air flow that passes through an evaporator and keeps the open showcase cool. By the way, a normal open showcase is equipped with only one evaporator, and when defrosting it,
As the temperature inside the refrigerator and therefore the temperature of the product rises, the product is likely to become damaged, and this makes it necessary to shorten the shelf life of the product.
This leads to product loss and product loss, which puts pressure on business profits. Therefore, in order to keep the temperature rise inside the open showcase as low as possible during defrosting, two evaporators have recently been installed in one open showcase, and in defrosting mode, one evaporator is While performing cooling operation,
A defrosting method (hereinafter referred to as a continuous cooling liquid refrigerant defrosting method for convenience) has been developed in which a high temperature liquid refrigerant is injected into the other evaporator to perform a defrosting operation. Next, the contents of this continuous cooling liquid refrigerant defrosting system will be explained using FIGS. 3 to 5. Figure 3 is a cross-sectional view of an open showcase using such a defrosting method, Figure 4 is a refrigerant circuit diagram of the open showcase shown in Figure 3, and Figure 5 is the operation of the open showcase shown in Figure 3. This is an explanatory diagram of the modes, and the figure shows the flow of refrigerant in the refrigerant circuit according to various operation modes. In the open showcase shown in FIG. 3, an inner box 2 and a partition plate 3 are provided inside a main case 1 having an opening 01 on the front surface, and an inner ventilation passage 4 is formed by the inner box 2 and partition plate 3. , an inner ventilation fan 7 that blows circulating air into this inner ventilation passage 4, and evaporators 5a and 5 that divide a part of this inner ventilation passage 4 into two by a partition plate 14 and cool the circulating air.
b. Further, an outer ventilation passage 5 is formed by the main body case 1 and the partition plate 3, and a reversible outer ventilation fan 8 for blowing circulating air into the outer ventilation passage 5 is provided. Inside ventilation duct4. At both ends of the outer ventilation passage 5, there are an outlet 9.10 for blowing out the circulating air and an inlet 11.1 for sucking the circulating air.
2 are provided. A damper 15 is arranged above the evaporators 5a and 5b to block the evaporator outlet air via an electric motor (not shown) that can rotate forward and backward. Note that the position of the damper when the damper 15 is vertical as shown by the solid line in the figure is b, and the position of the damper that blocks the outlet air of the evaporator 6a is C1, which is also the same as the dotted line in the figure. As shown by the dotted line in the figure, the position of the damper that blocks the outlet air of the evaporator 6b is indicated by a. Next, in FIG. 4, a solenoid valve 16a for controlling the refrigerant is provided in the refrigerant circuit on the inlet side of each evaporator 6a, 6b. 15b, 16C1 expansion valves 17a, 17b - and check valve 1
9 is provided, and the end of the pipe is connected to the condenser 18b of the condensing unit 18. In addition, electromagnetic valves 16d and 1 are provided in the refrigerant circuits on the outlet side of each evaporator 6a and 6b.
6e and a check valve 19 are provided, a part of which is connected to the inlet side piping to form a bypass circuit BP, and an end of the piping is connected to the compressor 18a of the condensing unit 18. Next, to explain the operation in FIG. 4 with reference to FIGS. 3 and 5, in the simultaneous cooling mode (modes A and D in FIG. 5), both the evaporator 5a and the evaporator 6b perform cooling operation. It is. That is, the refrigerant that has become high temperature and high pressure due to the compression 118a is liquefied in the condenser 18b, and passes through the electromagnetic valve 16b, which is in an open state, to the expansion valve 17a. The refrigerant is injected into the evaporators 6a and 6b from the evaporators 17b and evaporated, and the heat of evaporation is taken from the circulating air passing through the evaporators 6a and 6b to cool it.
The air returns to the compressor 18a via 13d and 16e for circulation, and the flow of air at this time is as shown by the arrows in FIG. That is, the circulating air cooled by the evaporators 5a and 5b is blown out from the outlet 10 by the inner blower fan 7 to form an air curtain A in the opening 01, thereby cooling the products on the display shelves 13 in the case product display room. It flows downward, flows to the suction port 12, and is cooled again by the evaporators 6a and 6b. In addition, the air curtain B is designed such that circulating air having a higher temperature than the circulating air in the inner ventilation passage 4 is blown out from the air outlet 9 through the outer ventilation fan 8 provided in the outer ventilation passage 5 to protect the air curtain A. It flows downward and is collected from the suction port 11 while forming a pore, thereby improving the cooling efficiency. The position of the damper 15 at this time is b, and the evaporators 5a, (
It faces upward so that the circulating air passing through the ib can flow through it. Next, after a certain period of time after frost has formed in the evaporators 5a and 5b, defrosting is performed in defrosting modes such as modes B and E in FIG. For example, in the case of mode E, the damper 15 is rotated to the position a by a control signal so as to block the air blown from the evaporator 6b, and only the solenoid valves 15c and 16d are opened, and the refrigerant is discharged as shown in FIG. Flowing like an arrow. That is, the liquefied refrigerant, which is liquefied at high pressure in the condenser 18b at a temperature close to 40° C., passes through the electromagnetic valve 16C, flows into the evaporator 6b, and performs defrosting by dissolving and removing frost attached to the evaporator 6b. At this time, the refrigerant is cooled to a low temperature. Therefore, the refrigerant exiting the evaporator 6b passes through the bypass circuit BP via the check valve 19, passes through the check valve 19 again, passes through the expansion valve 17a, and evaporates in the evaporator 6a, thereby cooling the circulating air. The gaseous refrigerant is then recovered to the refrigerator 18a through the electromagnetic valve 16d and circulated again. The above explanation describes the case of defrosting the evaporator 6b and cooling the evaporator 6a, but in mode B. That is, in the case of defrosting the evaporator 6a and cooling the evaporator 6b, the position of the damper 15 is set to C, and the solenoid valve 16a is set to the position C. This is possible if 16e is controlled to be in an open state. Modes C and F in Fig. 5 are modes in which sufficient refrigerant remaining in the defrosted evaporator is recovered to the compressor 18a side, and at this time, the water draining after defrosting of the evaporator concerned is It will be done. For example, in mode F, the solenoid valve 16c at the refrigerant inlet is closed from the state of mode E, and the solenoid valve 16d is further opened for a certain period of time (approximately 5 minutes) to recover the refrigerant in the defrosting side evaporator 6b to the compressor 18a side. During this time, drain the water from the evaporator 6b. This is because if the simultaneous cooling mode is entered with water still attached to the evaporator 6b, the water will freeze and form an ice bank, causing a reduction in the cooling capacity. Similarly, in mode C, the refrigerant is recovered and drained from the evaporator 6a, which is on the defrosting side. That is, this mode C
In this case, operation is performed from the mode B state by closing the solenoid valve 16a and opening the solenoid valve 16e for a certain period of time. In this way, driving mode A→B→C-4D-4E→F
-A, the period from mode A to the next mode A is considered to be a driving cycle, and this driving cycle time (also referred to as driving cycle period) is controlled by a changeover switch or the like in 3.4.5.
The setting can be changed to 6 hours.

[Problems to be solved by the invention]

By the way, in the above-mentioned defrosting mode, the temperature of the evaporator rises when defrosting is finished, so the temperature of the evaporator is measured, and when the temperature of the evaporator reaches a certain temperature, it is assumed that defrosting has finished. Have a child. FIG. 6(8) thus shows an example of mode transitions during a driving cycle that occurs under hot and humid conditions, and FIG. 6(B) shows a similar example of mode transitions that occur under low temperature and dry conditions. That is, in the open showcase using the continuous cooling liquid refrigerant defrosting method as described above, the operation cycle time is arbitrarily set by a switch, which causes the following problems. ■In high temperature and humidity conditions, the operation cycle time TO is shown in Figure 6 (,
If it is set to a long time like A), the amount of frost will increase, so it will take too long to defrost, and the time for the product temperature to rise will be longer, making it difficult to keep the product temperature rise to a minimum even when the evaporator on one side is in operation. I can't get the desired characteristics. In addition, frost tends to remain without being completely defrosted, causing ice banks. Unlike normal frost, this ice bank has a low temperature and is difficult to remove during defrosting. ■On the other hand, if the time of the simultaneous cooling mode during the operation cycle is set to be the same as that shown in Figure 6 (A) in a low dry state, the operation cycle time TO in this state is shown in Figure 6 (B).
)become that way. In this case, although there is not much frost on the evaporator, frequent defrosting is attempted, which leads to an unnecessary rise in product temperature. ■In order to eliminate the above problem ■■, it is necessary to change the operating cycle time TO using a switch according to the surrounding environment, but this work is complicated and requires experience, so it is not practical as a practical matter. Difficult to implement. An object of the present invention is to provide an operation control device for an open showcase using a continuous cooling liquid refrigerant defrosting method that automatically sets the operation cycle time based on the time spent on defrosting, thereby changing the operation cycle time. The object of the present invention is to operate an open showcase using a continuous cooling liquid refrigerant defrosting system, which eliminates the need for such operations and efficiently maintains cooling in an appropriate operation cycle time.

[Means to solve the problem]

In order to achieve the above-mentioned object, the control device of the present invention has two refrigerants that are circulated and supplied from a common compressor (such as 18a).
A device for controlling the operation of an open showcase equipped with a set of evaporators (6a, 6b, etc.), comprising: a simultaneous cooling mode in which both of the evaporators perform refrigerant operation; An operation control device that repeats an operation cycle that includes at least a defrosting mode in which an evaporator performs a cooling operation while the other set of evaporators performs a defrosting operation. A defrosting time measuring means (such as a CPU not shown) that calculates the time required to defrost the evaporator (TD, etc., hereinafter referred to as defrosting time) of the evaporator that is the target of defrosting, via a temperature measuring means, etc. ), and when the defrosting time becomes longer (shorter), the period of the operation cycle (operation cycle time TO, etc.). Alternatively, the apparatus may be equipped with an operation cycle variable setting means (such as a CPU not shown) that sets the time of the simultaneous cooling mode (simultaneous cooling time TC, etc.) to be shorter (longer) in a predetermined relationship.

[For use]

The defrosting time measurement time measures the time spent on defrosting, and if the defrosting time is short, the operating cycle variable setting means increases the operating cycle time or simultaneous cooling mode time (simultaneous cooling time) and sets the defrosting time. If it is long, the operation cycle time or simultaneous cooling time is automatically set to be short.

【Example】

The present invention will be explained in detail below based on FIGS. 1 and 2. FIG. 1 is a flowchart illustrating the operation of automatically setting driving cycle time as an embodiment of the present invention, and FIG. 2 is a time chart showing mode transitions in various driving cycles of the present invention. First, the flowchart of FIG. 1 will be explained. In the present invention, an operation control device (not shown) including a CPU or the like is provided. This control device measures the temperature of the evaporator 6a (6b) at least during defrosting operation from the time when defrosting of the open showcase is started using the continuous cooling liquid refrigerant defrosting method described in the prior art section. to determine when the temperature reaches a predetermined temperature (step 101), and at the same time determine the time required for this defrosting (step 101).
Determine the defrosting time TD. Therefore, this defrosting time TD is 0
If minutes≦TD≦5 minutes, the operation cycle time TO is set to 6 hr in order to lengthen the simultaneous cooling mode time (referred to as simultaneous cooling time) TC (step 103). Also 5
If minutes<TD≦10 minutes, the driving cycle time TD is set to 5 hr in order to slightly lengthen the simultaneous cooling time TC (step 104). Also, if 10 minutes < 70520 minutes, defrosting takes a little time, so to shorten the simultaneous cooling time TC a little, the operation cycle time TO is set to 4 hr (step 105), and 20 minutes < TD ≦ If it is 30 minutes, to further shorten the cooling mode time, the operation cycle time T
O is set to the shortest value of 3 hr (step 106). The next operation continues according to the operation cycle time TO set as described above. However, when the open showcase is operated for the first time after being installed, an appropriate defrosting time TD and operation cycle time TO are initialized according to a flow chart not shown, and a simultaneous cooling operation is started. Next, the time chart of FIG. 2 showing the transition of the operating mode according to the present invention will be explained. Since the operation mode proceeds with defrosting, draining, and simultaneous cooling, the next operation cycle time To is shortened or extended according to the operation cycle time TO determined by the defrosting time TD in the procedure shown in FIG. In other words, when operating at a short operating cycle time To as shown in Fig. 2 (A), for example, if the operating cycle time TO is 3 hr and the defrosting time TD is 5 minutes, then the next operation is as shown in Fig. 2 (A). B
), the long operation cycle time To of 6 hours is automatically set and operation continues. In addition, if the operation is performed at a long 6 hr operation cycle time To as shown in Figure 2 (C), and the defrosting time TD is 30 minutes, then the short 3 hr operation cycle time is shown in Figure 2 (D). The cycle time To is automatically set and operation continues. In this way, the defrosting time TD is measured and the appropriate operation cycle time TO is determined.
is set automatically. Further, instead of automatically switching and setting the operating cycle time TO in accordance with the defrosting time TD as described above, the simultaneous cooling time TC may be automatically set.

【Effect of the invention】

According to this invention, in an open showcase in which defrosting is performed using a continuous cooling liquid refrigerant defrosting method, the defrosting time TD is measured, and the operation cycle time To or the simultaneous cooling time TC is automatically set according to the measured time TD. As a result, the temperature rise inside this open showcase during defrosting is always suppressed to a minimum regardless of seasonal fluctuations, and the operating cycle time can be changed by manual switch depending on the season, etc. as in the past. There is no need to change settings, and the open showcase can always be operated in a highly efficient state.

[Brief explanation of drawings]

Fig. 1 is a flowchart explaining the operation of essential parts as an embodiment of the present invention, Fig. 2 is a time chart showing mode transitions in various operation cycles of the present invention, and Fig. 3 is a continuous cooling liquid refrigerant defrosting system. 4 is a refrigerant circuit diagram of the open showcase shown in FIG. 3, FIG. 5 is an explanatory diagram of the operation mode of the open showcase shown in FIG. 3, and FIG. 6 is a conventional 3 is a time chart showing mode transitions in the driving cycle of the vehicle. TO two operation cycle time, TC: Simultaneous cooling time, TD:
Defrosting time, 1: Main case, 6a, 6b: Evaporator, 16
a to 16e: solenoid valve, 17a, 17b: expansion valve,
18: combing unit, 18a: compressor, 18
b: Condenser, 19: Check valve. Fang 3 illustration Fang 4

Claims (1)

[Claims] 1) A device for controlling the operation of an open showcase equipped with two sets of evaporators to which refrigerant is circulated and supplied from a common compressor, wherein the evaporators are caused to perform refrigerant operation together. Repeating an operation cycle including at least a simultaneous cooling mode and a defrosting mode in which one set of evaporators among the evaporators performs a cooling operation while the other set of evaporators performs a defrosting operation. In the operation control device, the time required to defrost the evaporator targeted for defrosting (
a defrosting time measuring means for determining the defrosting time (hereinafter referred to as defrosting time); and when the defrosting time becomes longer (shorter), the period of the operation cycle or the time of the simultaneous cooling mode is shortened (longer) in a predetermined relationship; an operation cycle variable setting means to set;
An open showcase operation control device characterized by comprising: