JPH0463313B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a defrosting control method in a freezing/refrigerating case that cools a plurality of cases using one compressor.

(Conventional technology) Conventionally, in freezing and refrigerating cases where one compressor cools multiple cases,
The evaporators arranged in multiple show cases are connected to one compressor via an expansion valve and a condenser, and a solenoid valve is provided in the piping route connecting the compressor and each evaporator. A defrosting heater is installed in each of the defrosting heaters, and when defrosting, all solenoid valves are closed, the compressor is stopped and cooling is stopped, and each defrosting heater is energized to generate heat and the evaporator is heated. It melts and removes the frost that has formed.
In many cases, a common power source is used for the compressor and the defrosting heater, and when the defrosting heater generates heat, the power supply method of the power source is switched from the compressor to the defrosting heater.

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 uses one compressor to cool three cases a, b, and c, and the defrosting in the evaporators of each case a, b, and c takes one day. The defrost timer is set in advance so that defrosting can be performed for about 20 minutes, for example, every 8 hours. 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 melt and remove frost generated in the evaporator that generates heat. Electric power is continuously supplied to each defrost heater for the time set by the defrost timer. This defrosting time is set to be enough time to defrost the evaporator with the largest amount of frost among the evaporators. Then, when the defrost timer returns from defrost mode to cooling mode,
All defrosting heaters are de-energized, all solenoid valves are opened, the compressor is started, and refrigerant is supplied to the evaporator to cool the interior of each show case.

(Problem to be Solved by the Invention) However, in the conventional defrosting control method, the time for supplying power to the defrosting heater in each evaporator is
Because it is set to match the evaporator that takes the longest time to defrost, defrosting ends earlier than the internal temperature of case c, which takes the longest time to defrost, as shown in the temperature graph shown in Figure 2. There was a problem in that the temperature inside the storage cases a and b rose significantly above the defrosting end temperature, and the frozen and refrigerated products stored in the storage chambers were unnecessarily heated and their quality deteriorated. Additionally, there was a problem in that the cooling load increased due to the rise in temperature inside the refrigerator, and the cooling efficiency decreased significantly when cooling was restarted. In order to solve these problems, it may be possible to shorten the defrosting time, but conversely, frost remains in the evaporator and the cooling effect is hindered, making it impossible to sufficiently cool the products stored in the refrigerator. become unable.

The present invention has been made in view of the above-mentioned problems, and is a defrosting method for freezing and refrigerating cases that can prevent the temperature inside the refrigerator from rising during defrosting and efficiently remove frost generated in each evaporator. The purpose is to provide a control method.

(Means for Solving the Problems) In order to achieve the above object, the present invention connects evaporators respectively arranged in a plurality of show cases to one compressor via an expansion valve and a condenser. A current valve is installed in each piping route connecting the and each evaporator, and when the defrost timer goes into defrost mode, all solenoid valves are closed to stop compressor operation, and a current valve is installed in each case. In a defrosting control method for freezing and refrigerating cases in which defrost heaters installed in each case are energized to remove frost generated on the evaporator, each case is equipped with a defrost sensor that detects the completion of defrosting the evaporator. When each defrost sensor detects the end of defrosting of an evaporator, the power supply to the defrost heater corresponding to the evaporator is stopped, and when defrosting of a predetermined number of evaporators among the total number of evaporators is completed, Only the solenoid valve connected to the evaporator that has been defrosted is opened to start compressor operation, and when a predetermined amount of time has elapsed after defrosting of a predetermined number of evaporators has been completed, the remaining defrost is removed. The feature is that the heater is de-energized and the remaining solenoid valves are opened.

(Operation) According to the present invention, the defrosting time and time are preset by a defrosting timer, and defrosting in each evaporator is performed when the defrosting timer enters the defrosting mode. When the defrost timer enters the defrost mode, first all the solenoid valves are closed to suppress the flow of refrigerant and the operation of the compressor is stopped. and,
Each defrosting heater is energized.

At the stage when each defrosting sensor detects the end of defrosting of the evaporator, power supply to the defrosting heater corresponding to the evaporator is stopped. When the defrosting of a predetermined number of evaporators out of all the evaporators is completed, only the solenoid valve connected to the evaporator that has been defrosted is opened, and the compressor is started to operate. The inside of the show case is cooled by supplying refrigerant only to the inside of the case.

Then, after a predetermined period of time has elapsed after defrosting a predetermined number of evaporators, the remaining defrost heaters are de-energized, the remaining solenoid valves are opened, and refrigerant is supplied to the evaporators to supply the remaining evaporators to the remaining evaporators. The inside of the refrigerator is cooled.

That is, when the defrosting of a predetermined number of evaporators is completed, the defrosting heaters of the remaining evaporators that have not yet been defrosted are continuously energized for a while, and during this period, the defrosting heaters of the remaining evaporators are continuously energized. Since no refrigerant is supplied to the evaporator, this time can be used to melt and remove the frost remaining on the evaporator.

(Example) Fig. 1a is a cooling circuit diagram of a freezing/refrigerating case according to the present invention, in which 1A, 1
B, 1C are inner boxes 2A, 2B, 2C and outer boxes 3A, 3
B, 3C, each of the case 1A, 1B, 1C has ventilation passages 4A, 4B,
Inside 4C are evaporators 5A, 5B, 5C and blower 6.
A, 6B, and 6C are provided, respectively. In addition, an expansion valve 7 is provided on the inlet side of each evaporator 5A, 5B, and 5C.
A, 7B, and 7C are connected respectively.

A condenser 9 is connected to the discharge side of the compressor 8, and solenoid valves 10A and 10 are connected to the outlet side of the condenser 9.
The expansion valves 7A and 7 are inserted through the expansion valves B and 10C, respectively.
The inlet sides of B and 7C are connected to each other. Also,
The suction side of the compressor 8 is connected to the outlet side of the evaporators 5A, 5B, and 5C, respectively.

In addition, on the front side of each evaporator 5A, 5B, 5C, there are defrosting heaters HA, HB, which generate heat when energized.
HC is provided, and the ventilation passages 4A, 4
Defrost sensors SA, SB, and SC, which are thermostats, are provided in B and 4C to detect the completion of defrosting of each evaporator 5A, 5B, and 5C.

That is, in the freezing/refrigerating case, one compressor 8 is used to compress three cases 1A, 1.
B, 1C can be cooled, and the cooling of each case 1A, 1B, 1C can be controlled by opening and closing electromagnetic valves 10A, 10B, 10C interposed between the condenser 9 and each evaporator 5A, 5B, 5C. can do.

FIG. 1b is a configuration diagram of a defrosting control device according to the present invention, in which 11 is a control section consisting of a microprocessor, memory, etc., 12 is a main power supply section,
13 is an auxiliary power supply section. The control unit 11 sends control signals to the main power supply unit 12 and the auxiliary power supply unit 13 based on the input signals from the defrosting sensors SA, SB, and SC and the program stored in the memory. The main power supply unit 12 operates based on this control signal.
compressor 8, solenoid valves 10A, 10B,
10C and the defrosting heaters HA, HB, HC, respectively, and the auxiliary power supply unit 13 supplies the defrosting heaters HA, HB, HC connected to the auxiliary power supply unit 13 with predetermined driving power based on this control signal. Supply electricity.

Below, the flowchart of Figure 1c and Figure 1d
A defrosting control method in the freezing/refrigerating case shown in FIG. 1a 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 the cooling operation is being performed, it is determined whether the defrost timer T1 has entered the defrost mode (step 1). If the defrost mode is not set, return to step 1.

If it is determined in step 1 that the defrosting mode is on, the counter for counting the number of defrosting units is reset, and each solenoid valve 10A, 10B, 10C is
are closed respectively to suppress the flow of refrigerant, and the operation of the compressor 8 is stopped. At the same time, power is supplied from the main power supply section 12 to each of the defrosting heaters HA, HB, and HC, and a timer T2 for monitoring the defrosting time is started (step 2).

Next, first, it is determined whether or not the defrost sensor SA detects the end of defrosting (step 3), and if it detects the end of defrosting, the main power supply unit 12 to the defrost heater HA is
At the same time as stopping the power supply from the terminal (step 4), 1 is added to the counter (step 5), and it is determined whether the counter value has reached 2 (step 6). If the defrosting sensor SA does not detect the end of defrosting, it is determined whether the current mode is the cooling mode (step 7).

Next, it is determined whether the defrost sensor SB has detected the end of defrosting (step 8), and if it has detected the end of defrosting, the power supply from the main power supply unit 12 to the defrost heater HB is stopped. Along with (Step 9),
Add 1 to the counter (step 10), and determine whether the counter value has reached 2 (step 10).
11). If the defrosting sensor SB does not detect the end of defrosting, it is determined whether the current mode is the cooling mode (step 12).

Next, it is determined whether or not the defrost sensor SC detects the end of defrosting (step 13), and if the end of defrost is detected, the power supply from the main power supply unit 12 to the defrost heater HC is stopped. together (step 14),
Add 1 to the counter (step 15), and determine whether the counter value has reached 2 (step 15).
16). If the defrosting sensor SC does not detect the end of defrosting, it is determined whether the current mode is the cooling mode (step 17).

If the counter value does not reach 2 in step 16, the process returns to step 3 and the detection status of each defrosting sensor is checked again. In addition, if it is determined in steps 7, 12, and 17 that the system is not in the cooling mode, steps 8, 13, and 3 are entered respectively, and if it is determined that the system is in the cooling mode, all defrosting heaters HA, HB, and HC are activated.
At the same time, all electromagnetic valves 10A, 10B, 10C are opened, and the compressor 8 is started to operate, and each evaporator 5A,
Supply refrigerant to 5B and 5C to each case 1.
A, 1B, and 1C are cooled (step 18).

When the counter value reaches 2 in steps 6, 11, and 16, that is, in the illustrated example, the defrost sensor SA,
When SB detects the end of defrosting, defrost timer T1
is forced to return to cooling mode (step 19),
The power supply from the main power supply 12 to the remaining defrosting heaters HC is stopped, and the defrosting of the evaporators 5A and 5B is completed.
At the same time, only the solenoid valves 10A and 10B connected to the evaporators 5A and 5B are opened, and the compressor 8 starts operating, and refrigerant is supplied to the evaporators 5A and 5B.
The inside of the refrigerator 1B is cooled (step 20).

At the same time, power is supplied from the auxiliary power supply unit 13 to the defrosting heater HC of the evaporator 5C that has not yet been defrosted (step 21).

And a defrost sensor compatible with this evaporator 5C
The SC determines whether or not the end of defrosting has been detected (step 22), and if the end of defrosting is detected, the supply of power from the auxiliary power supply section 13 to the defrosting heater HC is stopped, and the remaining electromagnetic The valve 10C is opened and refrigerant is supplied to the evaporator 5C to cool the interior of the remaining case 1C (step 23), and the process returns to step 1.

If the defrost sensor SC does not detect the end of defrosting in step 22, it is determined whether a predetermined time has elapsed since defrosting started, that is, whether timer T2 has timed up (step 22). 24) If the predetermined time has elapsed, in step 23 the remaining solenoid valves 10C are opened and refrigerant is supplied to the evaporator 5C to cool the interior of the remaining case 1C, and the process returns to step 1. If it is determined that the predetermined time has not elapsed since defrosting was started, the process returns to step 21.

In this way, according to the embodiment, when defrosting of two of the three evaporators 5A and 5B is completed, all the defrosting heaters HA, HB, and HC are
The supply of power from the main power supply section 12 to the main power supply section 12 is stopped, and refrigerant is supplied to the two evaporators 5A and 5B that have been defrosted first to start cooling the case 1A and 1B. The supply of power from the main power supply section 12 is stopped to the defrosting heater HC of the evaporator 5C, which has not finished defrosting at the time when the supply of power from the main power section 12 is stopped, and the operation of the compressor 8 is started. Even after defrosting is started, the auxiliary power supply unit 13 remains in operation for a while until a predetermined time has elapsed, that is, until the defrost sensor SC detects the end of defrosting, or until a predetermined time elapses after defrosting has started. Since power is continuously supplied from the 1A and 1B, it is possible to shorten the defrosting time by quickly transitioning to cooling after defrosting the cases 1A and 1B, which have finished defrosting earlier. The frost remaining on the evaporator 5c can be melted and removed by the energization. Therefore, it is possible to efficiently remove frost formed not only on the evaporators 5A and 5B but also on the evaporator 5C, which takes time to defrost. Also, the first
As shown in the temperature graph shown in Figure d, the internal temperatures of case 1C, which takes the longest time to defrost, and cases 1A and 1B, where defrosting ends quickly, can be averaged around the defrosting end temperature. During times of frost, the internal temperature of a specific case will rise compared to the internal temperature of other cases, and the frozen/refrigerated products stored in that case will not be unnecessarily warmed, and the internal temperature will rise. This will not increase the cooling load and reduce the cooling efficiency when cooling is restarted.

In addition, in the above embodiment, three cases were cooled by one compressor, but
Of course, the number of show cases may be increased or decreased as appropriate. Further, in the embodiment described above, power is continuously supplied from the auxiliary power supply unit 13 to the defrosting heater HC of the evaporator 5C, which has not finished defrosting at the time when the power supply from the main power supply unit 12 is stopped. However, the continuous supply of power may be performed from the main power supply unit without using the auxiliary power supply unit.

(Effects of the Invention) As described above, according to the present invention, when defrosting of a predetermined number of evaporators among the total number of evaporators is completed, the power supply to the defrosting heater corresponding to the evaporator is stopped, The refrigerant is supplied to the evaporator that has been defrosted first to start cooling the show case, and when the predetermined number of evaporators have been defrosted, the remaining evaporators that have not yet been defrosted are defrosted. Since the heater continues to be energized for a while until a predetermined period of time has elapsed, a case where defrosting has finished early can be quickly cooled down after defrosting. Furthermore, it becomes possible to completely remove the frost remaining in the evaporator, which takes time to defrost. Therefore, the internal temperature of each case can be averaged around the defrosting end temperature, and when the internal temperature of a specific case is higher than that of other cases during defrosting, The 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 in the refrigerator and the cooling efficiency is not decreased when cooling is restarted.

[Brief explanation of drawings]

1a to 1d show embodiments of the present invention, in which FIG. 1a is a cooling circuit diagram of a freezing/refrigerating case, FIG. 1b is a configuration diagram of a defrosting control device, and FIG. FIG. 1c is a flowchart of defrosting control, FIG. 1d is a time chart of defrosting control, and FIG. 2 is a time chart of conventional defrosting control. 1A, 1B, 1C... Show case, 5A, 5
B, 5C... Evaporator, 8... Compressor, 10A, 1
0B, 10C...Solenoid valve, HA, HB, HC...Defrost heater, SA, SB, SC...Defrost sensor.

Claims (1)

[Claims] 1. Evaporators arranged in a plurality of show cases 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. When the defrost timer enters defrost mode, all solenoid valves are closed to stop compressor operation, and the defrost heater installed in each case is energized to restart the evaporator. In the defrosting control method for freezing and refrigerating case cases, each case is equipped with a defrost sensor that detects the completion of defrosting of the evaporator. When this is detected, the defrosting heater corresponding to the evaporator is de-energized, and when defrosting of a predetermined number of evaporators among the total number of evaporators is completed, a solenoid valve connected to the evaporator that has been defrosted is activated. When a predetermined number of evaporators have been defrosted and a predetermined amount of time has elapsed, the remaining defrost heaters are de-energized and the remaining solenoid valves are opened. A defrosting control method for a frozen/refrigerated case.