JPS6024388B2 - Defrost control device - Google Patents

Description

[Detailed Description of the Invention] The present invention is applicable to, for example, frozen and
The present invention relates to a defrosting device for refrigeration equipment, and particularly to a device for efficient defrosting.

Conventionally, the defrosting of the cooler of a freezing/refrigerating device has been carried out using a timer device at predetermined cumulative time intervals from the end of the previous defrosting.

Since the predetermined cumulative time interval using this method is generally determined based on the operating conditions that cause the most frost formation, defrosting is performed even when there is little frost and defrosting is unnecessary, resulting in poor product temperature management and There were many inconveniences from an energy saving perspective. In recent years, this method has been improved and is now widely used in household refrigerators.
In other words, there is a defrosting control method that integrates the closing time of the internal temperature regulator and starts defrosting when it reaches a predetermined value.

This method has an automatic function that allows the defrost interval to be matched to the load of the cooler, that is, when the load is low, the defrost interval is longer, and when the load is high, the defrost interval is shortened. Although the device is simple and ingenious in that the only accessory device is a time integrator, it has the following drawbacks. That is, when the refrigerator starts intermittent operation, when the refrigerator stops, the frost layer on the heat transfer surface of the cooler naturally partially melts, the density of the frost increases, and the thickness of the fog layer decreases. Furthermore, if the operating rate of the refrigerator becomes smaller and the stop time becomes longer relative to the operating time, the fog layer may hardly grow. Considering such a case, the setting cumulative time of the defrosting control device based on the conventional example of cumulative operation time is based on the case of continuous operation of one refrigerator, and is designed assuming the worst case in use. It can be seen that defrosting is carried out more frequently than necessary in practical operation, including actual intermittent operation. In particular, open showcases installed in supermarkets and the like have large openings and have a very large outside air load.

Therefore, when the refrigerator is stopped or the flow of cold soot in the cooler is stopped by the temperature controller, the inlet air temperature of the cooler installed in the air path of the open showcase rises immediately, causing the cooling The frost on the container will melt quickly. In such a cooling system, if the conventional system is implemented, the defrosting frequency will be completely more than necessary. In other words, the conventional defrosting control system based on operation time integration is applicable to household refrigerators and other devices that have a closed storage to be cooled, or in other words, the inlet air temperature of the cooler does not rise much even when the cooling operation is stopped. However, in cooling systems such as open showcases, where the air temperature at the inlet of the cooler quickly rises while cooling operation is stopped, defrosting becomes more frequent than necessary.
It can be said that it is not very suitable. Furthermore, in the conventional example, a defrosting termination device is provided to terminate defrosting when the temperature of the cooling means rises above a predetermined temperature, but due to a malfunction of this defrosting termination device, defrosting failure may occur. As a result, it is not uncommon for malfunctions to occur, such as damage to equipment or damage to stored products. The present invention has been made in order to improve the drawbacks of the above-mentioned conventional examples, and the time interval for defrosting (hereinafter referred to as the defrost interval) is changed to the time period during which the cooler is performing cooling operation, that is, By changing the cooling operation rate (hereinafter referred to as operation rate) to obtain the optimal defrost start time, and by using the cooled room temperature detector as an auxiliary means for the defrost termination device, more reliable defrost can be achieved. It is intended to provide a control device.

In order to clarify the advantages of the present invention, the second algorithm for determining the defrosting start time will be explained in detail below.

FIG. 2 is an operational characteristic diagram of an open showcase cooling system, which was obtained through experiments and is used to explain the algorithm of the defrosting method of the present invention.

In Figure 2, the machine axis is the elapsed time after the end of defrosting, the vertical axis is the operating rate, and the parameters A and B are when the air conditions around the open showcase are different, and A is the case where the ambient air condition is different compared to B. This is the case when the enthalpy of is high.

From FIG. 2, it can be seen that in case B, the operating rate is constant with respect to the elapsed time, and from this it can be seen that the characteristics of the cooler do not deteriorate due to frost formation.

In case A, the operating rate increases as time passes and finally becomes continuous operation, indicating that in this case the characteristics of the cooler have deteriorated due to spring frost. In this way, it has been found that there are regions where defrosting is virtually unnecessary depending on the operating rate, and conversely, if these characteristics are clarified, it will be possible to obtain accurate information on when to start defrosting based on the operating rate. It turns out that it is possible. FIG. 3 is an explanatory diagram in which what kind of defrosting interval is suitable for the operating rate was studied based on experiments such as those shown in FIG. 2.

Characteristic curve A is a conventional example in which defrosting is performed when the cumulative operating time reaches the set defrost interval.For example, at an operating rate of 50%, it is twice the defrosting interval during continuous operation, and the operating rate is 40%. Then, the sound will be 2.3.If the defrost interval is 1, the operation rate is , and the defrost interval during continuous operation is lo, then 1=lo/(of=0 to 1)
). However, as mentioned above, in this case, the frequency of defrosting becomes higher than necessary. The present invention determines the defrosting interval based on the operating rate as explained in Fig. 2, and attempts to select an appropriate defrosting start time. Indicates the appropriate defrost interval.

Such a characteristic curve can be obtained by performing numerous experiments such as those shown in FIG. 2, and is specific to a particular showcase and its cooling system. The present invention is intended to determine in advance an appropriate defrosting interval for the above-mentioned operating rate, and thereby to know when to start defrosting the cooler.

The details of the present invention will be explained below according to the illustrated embodiments.

FIG. 1 is an overall configuration diagram showing an embodiment in which a defrosting control device according to the defrosting control method of the present invention is applied to a cooling system for an open showcase. In the figure, 1 is an open showcase that is a load, 2 is a refrigerator that is a cooling heat source,
3 is a freezing channel, 4 is a cold soot shield valve disposed in the liner medium channel 3, 5 is a cold soot expansion valve, and 6 is disposed in the air channel of the open showcase 1. 7 is a defrosting means for melting the frost on the cooler 5; 3 is a temperature detector for detecting the temperature inside the open showcase; 9 is a controller. Further, 30 is a temperature detector for outputting the temperature of the cooler to the defrosting end detector 3, and is attached to the cooler 5.
The operation of the oven showcase cooling system configured as above will be explained below. The high-pressure refrigerant liquid produced by the refrigerator 2 passes through the refrigerant flow path 3, and if the shutter valve 4 is open, it is depressurized by the expansion valve 5 and evaporated by the cooler 6, and flows through the air path inside the open showcase 1. The air passing through is cooled, becomes low-pressure cold soot gas, and returns to the refrigerator 2. In Fig. 1, in order to think more generally, there is not a one-to-one correspondence between the refrigerator and open showcase 1, but instead there is a plurality of other open showcases (not shown) that serve as loads on the refrigerator. 2
It is connected to the flow path indicated by the broken line in FIG. The temperature detector 8 detects the temperature inside the open showcase 1, and the controller 9 receives the signal from the detector 8, opens and closes the shutter valve 4, and adjusts the temperature inside the open showcase 1. conduct.

The controller 9 also integrates the open time of the valve 4 and calculates the cooling operation ratio of the open showcase 1 (hereinafter simply referred to as the operation ratio).
Calculate. The time to start defrosting is determined as follows. First, the set value for the cumulative opening time of the sheath valve 4 is determined based on the operating rate starting from the end of the previous defrosting operation, and when the cumulative opening time of the sheath valve 4 reaches the set value. At the same time, a defrosting signal is output from the controller 9 to the defrosting means 7. The operation of the controller 9 will be explained in detail below. FIG. 4 is a control circuit block diagram for explaining the operation of the controller 9 in FIG. 1.

In this figure, reference numeral 10 indicates an internal temperature signal that is input to the temperature control circuit 12, and a cooling means ON signal 9 (see FIG. (opening/closing of the shutoff valve 4) is output. Reference numeral 13 denotes an on-time integration timer circuit that integrates the output time of the on-signal from the temperature control circuit 12.

14 is an elapsed time integration timer circuit which outputs the elapsed time since the end of the previous defrosting.

Reference numeral 15 denotes an operation rate calculation circuit which calculates the operation rate based on the output of the on-time cumulative time of the on-time cumulative timer circuit 13 and the elapsed time output of the elapsed time cumulative timer circuit 14.

A defrosting interval setting circuit 16 receives an initial defrosting interval setting input 17 from the outside and initializes the defrosting interval.

Further, the operating rate calculation circuit 15 determines and outputs a preset amount of the defrosting interval according to the operating rate to the defrosting interval setting circuit 16. Thereby, the preset amount of the defrost interval changes dynamically depending on the operating rate. Further, the on-time integration timer circuit 13 also outputs the on-time integration value to the defrosting interval setting circuit 16.
The defrost interval setting circuit 16 determines when the on-time integrated value by the defrost interval setting circuit 16 reaches the defrost interval preset by the operation rate calculation circuit 15.
A defrosting signal 20 is output to the defrosting means 7 shown in FIG. At this time, the defrosting output 10 is also input to the gate 18, and the output of the on signal 19 is stopped. Also, 21 is the cooler signal 2
2 is a defrost end detector for outputting a defrost end signal to the defrost end device 23 when the defrost end temperature is reached. Further, the defrosting termination device 23 is configured to terminate defrosting even when the internal temperature signal 1 reaches a predetermined temperature or higher. However, in this case, the defrost detector 21 is configured to detect the end of defrosting first when the vehicle is in a normal operating state. Next, an example of a specific defrost interval determination method will be described. When the operating rate calculation circuit 15 changes the defrost interval preset amount, the defrost interval is initially set from the outside in the defrost interval setting circuit 16. is, for example, the defrosting interval during continuous operation, and the initial setting amount is stored in the defrosting interval setting circuit 16. Depending on the operating rate, the operation rate calculation circuit 15 either outputs a change signal for the preset amount of the defrost interval to the defrost interval setting circuit 16, or uses the content of the signal as a coefficient to multiply the cut-off setting value, and the preset amount after the change is Set the initial setting value to be a coefficient corresponding to the operating rate. The coefficient may be determined based on the appropriate defrosting period as shown in Figure 3, and the value of the coefficient may be one that changes continuously depending on the operating rate, or it may be determined by dividing the operating rate to a certain extent (for example, one
00%≧operation rate>80% is the same number of systems, 80≧operation rate>7
0% may change stepwise (like other coefficients). When the preset amount is changed in this way using a coefficient corresponding to the operating rate, there are the following advantages. First of all, in open showcases where defrosting control is to be performed, the absolute value of the appropriate defrost interval will naturally differ greatly depending on the temperature range inside the cooler, but as mentioned above, the defrost interval during continuous operation is The ratio, that is, the coefficient corresponding to the above-mentioned operation, does not differ greatly even in open showcases in different temperature ranges inside the refrigerator. That is, first external input,
Alternatively, if only the initial setting value of the defrost interval (defrost interval during continuous operation) set in the defrost interval setting circuit 16 by human operation input is set to the value of the open showcase to be controlled, the control can be performed. The container can be commonly used for open showcases with various internal temperature ranges. If we think further, the controller 9 in Fig. 4
has a temperature adjustment circuit 12 that controls the temperature inside the shield,
Since this temperature control circuit 2 is given a setting input 11 for the temperature inside the oven showcase, the input 11
can be used to set the initial defrost interval from the temperature adjustment circuit 12 to the defrost interval setting circuit 16. This is because, as described above, the defrosting interval during continuous operation is determined depending on the temperature range inside the cold storage refrigerator. With this configuration, by simply setting the temperature, the optimum defrosting interval will be automatically selected for any open showcase in any temperature range, and defrosting will be carried out easily and efficiently.

In the case of the second embodiment, an efficient defrosting cycle can be obtained without requiring any new detection means, and if the controller 9 in FIG. 1 is realized by a fin circuit means or the like, In carrying out the present invention, there are no problems with cost, reliability, etc.

Furthermore, according to this embodiment, even if the amount of frost increases rapidly for some reason and the cooling efficiency decreases, the operation rate increases accordingly, and the defrost interval is corrected to be shorter by the above-mentioned function. Therefore, no problems occur, it can cope with any load fluctuations, and efficient defrosting is always performed. Also, even if the defrost end detector does not output the defrost end signal for some reason,
Since defrosting is terminated by the temperature sensor 8 inside the refrigerator, a more reliable defrosting control system can be obtained.As explained above, according to the present invention, efficient defrosting is always possible. You can choose when to start frosting, which has practical effects such as power saving and preventing the temperature inside the refrigerator from rising.

[Brief explanation of the drawing]

Fig. 1 is an overall configuration diagram showing an embodiment of a defrosting control device according to the defrosting control method of the present invention applied to a cooling system of an open showcase, and Fig. 2 illustrates the defrosting method of the present invention. Fig. 3 is an explanatory diagram showing the appropriate defrosting interval for the operating rate in the open showcase cooling system, and Fig. 4 shows the operation of the control device in Fig. 1. It is a control circuit block diagram for explanation. In the figure, 7 is a defrosting means, 8 is a temperature detector, 9a is a temperature control bag counterfeit, 3b is a defrost interval control device, 21 is a defrost end detector, 23 is a defrost end bag counterfeit, and 30 is a temperature detector. It is a vessel. Note that the same reference numerals in the figures indicate the same or corresponding parts. Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Scope of Claims] 1. A defrosting means of a cooler that cools a room to be cooled, and a defrosting means of a cooler that cools a room to be cooled, and a defrosting means for a cooler that cools a room to be cooled based on a detection signal and a set temperature signal of a first temperature detector that detects the temperature of the room to be cooled. A temperature control device that controls on/off the cooling operation, and a temperature control device that stores the relationship between the cooling operation rate of the cooler and a predetermined appropriate defrosting interval, and also stores the cooling operation rate of the cooler after the end of the previous defrosting. a defrosting interval control device that calculates the defrosting means and operates the defrosting means when the elapsed time from the end of defrosting reaches an appropriate interval of the calculated cooling operation rate within the elapsed time, and the temperature of the cooler. A detection signal from a second temperature detector that detects the temperature of Defrost control device. 2. Claim 1 characterized in that the defrost interval control device is configured so that the appropriate defrost interval to be compared with the elapsed time is determined by multiplying the defrost interval during continuous operation by a predetermined coefficient. Defrosting device as described in section.