JPH01239367A - Defrosting control method for freezing and refrigerating showcase - Google Patents

Abstract

PURPOSE:To completely defrost the frost growth on the evaporators including the remaining frost left over from the previous defrosting by starting the power supply to the defrosting heater for those evaporators which were not completely defrosted in the previous defrosting operation earlier by a certain time period than to the defrosting heater for those evaporators which were completely defrosted. CONSTITUTION:When defrosting sensors SA, SB detect the completion of the defrosting, the fact that the evaporators 5A, 5B were defrosted is stored in memory. If the current defrosting operation is the second time, the evaporators which were defrosted are read, and the defrosting heater HC for the evaporator which has yet to complete the defrosting is singled out, and the power is supplied to it. The power supply to the defrosting heater, HC for the evaporator 5C is started earlier by a certain time period than to the defrosting heaters HA, HB for the evaporators 5A, 5B which were defrosted in the first time. By using such time, the frost growth on the evaporator including the remaining frost left over from the first defrosting operation can be completely defrosted.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a defrosting control method in a freezer/refrigeration showcase that cools a plurality of flow cases with one compressor.

(Prior art) Conventionally, in a freezing/refrigerating showcase in which multiple showcases are cooled by one compressor, evaporators placed in each of the multiple showcases are cooled by an expansion valve and a condenser. A solenoid valve is installed in each piping route connecting the compressor and each evaporator, and a heater for defrosting is installed in each showcase, and all solenoid valves are turned off during defrosting. The compressor is closed, the compressor is stopped, and cooling is stopped. At the same time, each defrosting heater is energized to generate heat and melt and remove the frost that has formed on the evaporator.

This conventional defrosting control method will be explained in detail below with reference to the time chart of FIG.

The time chart shown in Figure 2 is for cooling three showcases a, b, and c with one compressor.
Defrosting in the evaporators of each showcase a, b, c is 1
The defrost timer is set in advance so that defrosting can be performed for about 20 minutes, for example, every 8 hours throughout the day. When the defrost timer enters the defrost mode, first all solenoid valves are closed, the compressor is stopped, and cooling is stopped.

Then, each defrosting heater is energized to generate heat to melt and remove the frost generated on the evaporator. Each defrosting heater is continuously energized for the time set by the defrosting timer. This defrosting time is set to be enough time to defrost the evaporator with the largest amount of frost among the evaporators. and,
When the defrost timer returns from defrost mode to cooling mode, all solenoid valves are opened, the compressor starts operating, and refrigerant is supplied to the evaporator to cool the inside of each showcase. There is.

(Problem to be Solved by the Invention) However, in the conventional defrosting control method, the energization time of the defrosting heater in each evaporator is set according to the evaporator that takes the longest time to defrost. As shown in the temperature graph shown in Figure 2, compared to the internal temperature of showcase C, which takes the longest time to defrost, the internal temperature of showcases a and b, where defrosting ends earlier, is significantly higher than the defrosting end temperature. There was a problem in that frozen and refrigerated products stored in the refrigerator were heated unnecessarily and their quality deteriorated. Furthermore, there is a problem in that the cooling load increases due to the rise in temperature inside the refrigerator, and the cooling efficiency decreases significantly when cooling is restarted. In order to solve these problems, it may be possible to shorten the defrosting time, but conversely, frost remains in the evaporator and prevents the cooling effect, making it difficult to sufficiently cool the products stored in the refrigerator. become unable to do so.

The present invention has been made in view of the above-mentioned problems, and provides a freezing/refrigerating showcase that can prevent an increase in internal temperature during defrosting and efficiently remove frost generated in each evaporator. The purpose is to provide a defrosting control method.

(Means for Solving the Problems) In order to achieve the above object, the present invention connects evaporators arranged in a plurality of showcases to one unit via an expansion valve and a condenser.
A solenoid valve is installed in each piping route connecting the compressor and each evaporator, and when the defrost timer enters the defrost mode, all solenoid valves are closed and the compressor is In a defrosting control method for frozen/refrigerated showcases, the defrosting control method for freezing/refrigerating showcases includes stopping the operation of the machine and energizing the defrosting heaters provided in each showcase to remove frost generated in the evaporator.
Each showcase is equipped with a defrost sensor that detects the end of defrosting of the evaporator, and after defrosting has started, when each defrost sensor detects the end of defrosting of the evaporator, the defrost sensor corresponding to the evaporator is The defrost timer is forcibly returned to the cooling mode when a predetermined number of evaporators out of all the evaporators have been defrosted, and the remaining defrost heaters are de-energized. All solenoid valves are opened to start compressor operation, and at the next defrost time, when the defrost timer enters defrost mode, all solenoid valves are closed and compressor operation is stopped. In addition, the present invention is characterized in that the defrosting heaters of a predetermined number of evaporators whose defrosting was completed during the previous defrosting are energized with a delay of a predetermined time from other defrosting heaters.

(Function) According to the present invention, the defrosting time and time are set in advance by a defrosting timer, and defrosting in each evaporator is performed when the defrosting timer enters the defrosting mode.

During the first defrost after cooling operation starts, when the defrost timer enters the defrost mode, all solenoid valves are closed to suppress the flow of refrigerant and the compressor Operation will be stopped. Then, each defrosting heater is energized.

After defrosting is started, when each defrosting sensor detects the end of defrosting of the evaporator, power supply to the defrosting heater corresponding to the evaporator is stopped.

Then, when the defrosting of a predetermined number of evaporators among the total number of evaporators is completed, the defrost timer is forcibly returned to the cooling mode, and the energization of all remaining defrost heaters is stopped.
All the solenoid valves are opened, the compressor starts operating, and refrigerant is supplied to each evaporator to cool each showcase.

In addition, during the second and subsequent defrosts, when the defrost timer enters the defrost mode, all solenoid valves are closed and compressor operation is stopped, and the predetermined time when defrosting was completed during the previous defrost is set. The defrosting heaters of several evaporators are energized with a predetermined time delay compared to the other defrosting heaters.

That is, the defrosting heater of the evaporator whose frost was not completely removed during the previous defrosting is energized for a predetermined period of time earlier than the defrosting heater of the evaporator whose defrosting has been completed during the previous defrosting. Therefore, by using this energization time, it is possible to completely remove the frost that has formed on the evaporator, including the residual amount from the previous defrosting.

(Example) FIG. 1(a) is a cooling circuit diagram of a freezing/refrigerating showcase according to the present invention, and in the figure, LA.

IB and IC are inner boxes 2A, 2B, 2C and outer box 3A.

3B and 3C, and ventilation passages 4A and 4B for each showcase IA, IB, and IC.

Inside 4C are evaporators 5A, 5B, 5C and blower 6A.

6B and 6C are provided respectively. In addition, each evaporator 5A
, 5B, and 5C are connected to expansion valves 7A17B and 7C, respectively.

An evaporator 9 is connected to the discharge side of the compressor 8, and the expansion valves 7A, 7B are connected to the outlet side of the condenser 9 through electromagnetic valves 10A, 10B, and 10c, respectively.

The inlet sides of 7C are connected to each other. Further, the suction side of the compressor 8 is connected to the outlet side of the evaporators 5A, 5B, and 5C, respectively.

Further, on the front side of each evaporator 5A, 5B, and 5C, there are defrosting heaters HA and HB that generate heat when energized.

HC is provided, and the ventilation passages 4A14B, 4
Inside C is a defrost sensor 5ASSBSS consisting of a thermostat that detects the end of defrosting of each evaporator 5A, 5B, and 5C.
C is provided.

That is, in the frozen/refrigerated showcase, one compressor 8 can cool three showcases 1A, 11B and ICs, and a condenser and each evaporator 5A, 5B,
Cooling of each of the showcases IA, IB, and IC can be controlled by opening and closing electromagnetic valves 10A, IOB, and IOC interposed between the showcases IA, IB, and IC.

FIG. 1(b) is a configuration diagram of a defrosting control device according to the present invention. In the figure, 11 is a control section consisting of a microprocessor, memory, etc., and 12 is a power supply section. The control unit 11 sends a control signal to the power supply unit 12 based on the input signals from the defrosting sensors 5ASSB and SC and the program stored in the memory.

71! The S source section 12 controls the power supply section 1 based on this control signal.
Compressor 8, solenoid valve 10A, and IOB connected to 2.

10C and the defrosting heaters HASHB and HC, respectively.

The flowchart of FIG. 1(C) and FIG. 1(d) are shown below.
A defrosting control method in the freezing/refrigerating showcase shown in FIG. 1(a) will be explained with reference to the time chart of FIG.

The defrosting time and time are preset by the defrosting timer T1, and defrosting in each evaporator is performed when the defrosting timer T1 enters the defrosting mode.

First, while cooling operation is in progress, defrost timer T
1 is in defrost mode (Step 1
). If the defrost timer T1 is not in the defrost mode, the process returns to step 1.

If it is determined in step 1 that the defrost timer T1 is in the defrost mode, then it is determined whether or not the current defrosting is the first time (step 2).

If it is determined in step 2 that the current defrosting is the first time, the counter for counting the number of completed defrosting units is reset, and each solenoid valve 10A, 10B, and IOC are closed to prevent the refrigerant from flowing. is suppressed and the operation of the compressor 8 is stopped.

At the same time, the defrosting heaters HASHB and HC are energized (step 3).

If it is determined in step 3 that the current defrosting is the first time, it is first determined whether or not the defrost sensor SA has detected the end of defrosting (step 4). stops the power supply to the defrosting heater HA (step 5), adds 1 to the counter (step 6), and determines whether the counter value p<2 (step 7).
. If the defrosting sensor SA has not detected the end of defrosting, it is determined whether the current mode is the cooling mode (step 8).

Next, it is determined whether or not the defrost sensor SB has detected the end of defrosting (step 9), and if it has detected the end of defrosting, the defrost heater HB is de-energized (step 10).
), 1 is added to the counter (step 11), and it is determined whether the counter value has become 2 (step 12).

If the defrost sensor SB does not detect the end of defrosting,
It is determined whether the current mode is the cooling mode (step 13).

Next, it is determined whether or not the defrost sensor SC detects the end of defrosting (step 14), and if the defrost end is detected, the power supply to the defrost heater HC is stopped (step 1).
5), add 1 to the counter (step 16), and determine whether the counter value has become 2 (step 17)
. If the defrosting sensor SC does not detect the end of defrosting, it is determined whether the current mode is the cooling mode (step 18).

If the counter value does not reach 2 in step 17, the process returns to step 4 and the detection status of each defrosting sensor is checked again. Further, if it is determined in step 8.13.18 that the mode is not the cooling mode, the process proceeds to step 9.14.4, and if it is determined that the mode is the cooling mode, the process proceeds to step 21, which will be described later.

When the value of the counter becomes 2 in step 7.12.17, in the illustrated example, when the defrosting sensor 5ASSB detects the end of defrosting, the evaporator whose defrosting has ended at that point, that is, the evaporator 5A and evaporator 5B are stored (step 19).

Then, the defrost timer T1 is forcibly returned to the cooling mode (step 20), the remaining defrost operation, that is, the power supply to the defrost heater HC is stopped, and all the evaporators 5A, 5
The solenoid valves 10A, IOB, and IOC connected to the evaporators 5A and 5C are opened, and the compressor 8 is started to operate.
Supply refrigerant to B, 5C and showcase IA, IB, I
Cool the inside of the refrigerator C (step 21), and step 1
Return to

Then, while the cooling operation is being performed again, it is determined whether the defrost timer T1 has entered the defrost mode (step 1).

When it is determined in step 1 that the defrost timer T1 is in the defrost mode, it is then determined again whether or not the current defrosting is the first time (step 2).

Since this is the second defrosting, it is determined in step 3 that this is not the first defrosting, and first, the counter for counting the number of defrosting units is reset, and each solenoid valve 10 is reset.
A, IOB, and IOC are each closed to suppress the flow of refrigerant, and the operation of the compressor 8 is stopped (step 22).

Next, the defrosting completed evaporator 5 stored in step 19
A and 5B are read out (step 23), and from this information, the defrosting heater HC of the evaporator 5C whose defrosting has not been completed and whose frost was not completely removed during the previous defrosting is selected (step 2
4). Then, the selected defrosting heater HC is energized (step 25).

Next, start the delay timer T2 (step 26).
, monitors whether the time t2 set by the delay timer T2 has elapsed (step 27).

Then, when the delay timer T2 times up, the evaporators 5A and 5B whose defrosting has ended are read out again in one step (step 28), and the defrosting heaters HA and HB corresponding to the evaporators 5A and 5B are read out again. is selected (step 2
). Then, the selected defrosting heater HASHB is energized (step 30).

Then, as in the first defrosting, each defrost sensor SA, S
B. Check the detection status of SC, step 7, ]2.17
When the value of the counter reaches 2, the evaporator whose defrosting has been completed at that time is stored (step 19). During the second defrosting in the illustrated example, the defrosting sensor 5ASSC detects the end of defrosting and the counter value becomes 2, so this time the evaporators 5A and 5C are stored as the evaporators for which defrosting has ended. It turns out.

That is, during the second defrosting, the defrost heaters HA and HB of the two evaporators 5A and 5B, which were defrosted during the first defrosting, are not completely free of frost during the previous defrosting. Since the defrost heater HC of the evaporator 5C that has not yet finished defrosting is energized by a predetermined time t2 set by the defrost delay timer T2, the frost is completely removed during the first defrost. The defrosting heater HC of the evaporator 5C that was not defrosted is energized for a predetermined time t2 earlier than the defrosting heaters HA and HB of the evaporators 5A and 5B that have finished defrosting during the first defrosting. Using this energization time, it is possible to completely remove the frost that has formed on the evaporator, including the residual amount from the first defrosting. Similarly to the second defrosting, from the third defrosting time onward, if the defrosting heater of the evaporator has not been completely defrosted, the defrosting heater of the evaporator whose defrosting was not completely removed during the previous defrosting operation will be displayed. The defrosting heater of the evaporator is energized for a predetermined time t2 earlier than the defrosting heater of the evaporator, and it is possible to completely melt and remove the frost that has formed on the evaporator, including the residual amount from the previous defrosting. becomes.

As described above, according to the embodiment, at each defrosting time, when each defrosting sensor detects the end of defrosting, the power supply to the defrosting heater corresponding to the evaporator is stopped, and the power supply to the defrosting heater corresponding to the evaporator is stopped. 2 of them
When defrosting of one evaporator is completed, the remaining defrosting heaters are de-energized, all solenoid valves are opened, and the compressor starts operating to cool each showcase. As shown in the temperature graph shown in FIG. 1(d), the internal temperatures of each of the showcases IA, IB, and IC can be averaged around the defrosting end temperature. Therefore, during defrosting, the internal temperature of a specific showcase will not rise compared to the internal temperature of other showcases, and the frozen/refrigerated products stored in that showcase will not be unnecessarily warmed. The cooling load will not increase due to a rise in the temperature inside the refrigerator, and the cooling efficiency will not decrease when cooling is restarted.

In addition, during the second and subsequent defrosts, the defrost heaters of the evaporators whose defrost was not completely removed during the previous defrost will be replaced by the defrost heaters of the two evaporators whose defrost was completed during the previous defrost. Electricity is applied a predetermined time t2 before the defrosting heater of the evaporator, and this energization time is used to completely remove the frost that has formed on the evaporator, including the residual amount from the previous defrosting. Therefore, a large amount of frost does not remain on a particular evaporator and the cooling effect is not hindered, and an evaporator with a large amount of frost can be defrosted quickly.

In the above embodiment, three showcases are cooled by one compressor, but it goes without saying that the number of showcases may be increased or decreased as appropriate.

(Effects of the Invention) As explained above, according to the present invention, at each time of defrosting, when each defrost sensor detects the end of defrosting, the power supply to the defrost sensor corresponding to the evaporator is stopped, When a predetermined number of evaporators out of the total number of evaporators have been defrosted, power is turned off to the remaining defrosting heaters, and refrigerant is supplied to all evaporators to cool each showcase. The internal temperature of each showcase can be averaged around the defrosting end temperature. Frozen/refrigerated products stored in the refrigerator are not heated unnecessarily, and the cooling load is not increased due to a rise in the temperature inside the refrigerator and the cooling efficiency is not decreased when cooling is restarted.

In addition, during the second and subsequent defrosting, the defrosting heater of the evaporator whose defrosting was not completely removed during the previous defrosting is The evaporator's defrosting heater is energized for a predetermined period of time, and this energizing time can be used to completely remove the frost that has formed on the evaporator, including the residual amount from the previous defrosting operation. As a result, a large amount of frost does not remain on a particular evaporator and the cooling effect is not hindered, and an evaporator with a large amount of frost can be defrosted quickly.

[Brief explanation of the drawing]

1(a) to 1(d) show examples of the present invention, FIG. 1(a) is a cooling circuit diagram of a freezer/refrigeration showcase, and FIG. 1(b) is a defrosting circuit diagram. FIG. 1(e) is a flowchart of defrosting control, FIG. 1(d) is a time chart of defrosting control, and FIG. 2 is a time chart of conventional defrosting control. IA, IB, IC...Showcase, 5A, 5B. 5C... Evaporator, 8... Compressor, IOA, IOB,
10C...Solenoid valve, HA, HB, HC...Defrost heater, 5ASSB, SC...Defrost sensor. Patent applicant Sanden Corporation

Claims (1)

[Claims] Evaporators arranged in a plurality of showcases are connected to one compressor via an expansion valve and a condenser, and a solenoid valve is installed in a piping route connecting the compressor and each evaporator. , and closes all solenoid valves when the defrost timer enters defrost mode.
In the defrosting control method for freezing and refrigerating showcases, the compressor operation is stopped and the defrosting heaters installed in each showcase are energized to remove frost generated in the evaporator. A defrost sensor is installed in the case to detect the end of defrosting of the evaporator, and after defrosting has started, when each defrost sensor detects the end of defrosting of the evaporator, the defrost heater corresponding to the evaporator is activated. When a predetermined number of evaporators have been defrosted, the defrost timer is forcibly returned to cooling mode, and the remaining defrost heaters are de-energized. The solenoid valves are opened to start compressor operation, and at the next defrost time, when the defrost timer enters defrost mode, all solenoid valves are closed and compressor operation is stopped. A freezer/refrigeration showcase characterized in that the defrosting heaters of a predetermined number of evaporators whose defrosting has been completed during the previous defrosting are energized with a delay of a predetermined time from other defrosting heaters. Defrost control method.