JPH0461273B2 - - 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 each of the plurality of show cases are connected to one compressor via an expansion valve and a condenser, and a solenoid valve is provided for the piping route connecting the compressor and each evaporator. Each evaporator is equipped with a heater for defrosting, and during defrosting, all solenoid valves are closed, the compressor is stopped and cooling is stopped, and each defrost heater is energized to generate heat and evaporate. The frost that has formed on the vessel is melted and removed.

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 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. 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 interior of each show case. It's summery.

(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 case c, which takes the longest time to defrost, the internal temperature of cases a and b, where defrosting is completed earlier, is significantly higher than the defrosting end temperature. However, there was a problem in that the frozen and refrigerated products stored in the refrigerator were unnecessarily heated and their quality deteriorated.
Further, 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 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 is a method for removing freezing and refrigerating cases that prevents the temperature inside the refrigerator from rising during defrosting and efficiently removes frost generated in each evaporator. The purpose is to provide a frost 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 solenoid valve is installed in the piping route connecting the and each evaporator, and when the defrost timer enters the defrost mode, all the solenoid valves are closed, the compressor operation is stopped, and a In a defrosting control method for a freezing/refrigerating case in which defrost heaters provided in each are energized to remove frost generated on an evaporator, each evaporator is provided with an auxiliary heater,
A defrost sensor is installed in each case to detect the end of defrosting of the evaporator, and when the defrost timer enters defrost mode, all solenoid valves are closed and compressor operation is stopped. The heater and the auxiliary heater installed in the evaporator at the end of defrosting during the previous defrosting are energized, and after defrosting has started, when each defrosting sensor detects the end of defrosting of the evaporator, the evaporator is The defrost heater and the auxiliary heater corresponding to the defrost heater are de-energized, and when 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.
This system is characterized in that power supply to all remaining defrosting heaters and auxiliary heaters is stopped, and all solenoid valves are opened to start operating the compressor.

(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. When the defrost timer enters the defrost mode, first all the solenoid valves are closed, the operation of the compressor is stopped, and the flow of refrigerant is suppressed. and,
Each defrosting heater and the auxiliary heater provided in the evaporator at the end of defrosting during the previous defrosting are energized. Of course, during the first defrosting, only the defrosting heaters provided in each evaporator are energized.

After the defrosting is started, when each defrosting sensor detects the end of defrosting of the evaporator, power supply to the defrosting heater and the auxiliary 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 and auxiliary heaters is stopped. All the solenoid valves are opened, the compressor starts operating, refrigerant is supplied to each evaporator, and each show case is cooled.

In other words, in the evaporator at the end of defrosting where the frost was not completely removed during the previous defrosting, the auxiliary heater is energized in addition to the defrosting heater during the next defrosting. By utilizing the heat generated by both the evaporator and the auxiliary heater, it is possible to completely remove the frost that has formed on the evaporator, including the residual amount from the previous defrosting.

(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, each evaporator 5A, 5B, 5C is equipped with defrosting heaters HA1, HB1, HC1 that generate heat when energized.
and an auxiliary heater with a calorific value equal to or less than that of the defrosting heaters HA1, HB1, and HC1.
HA2, HB2, HC2 are provided, and in the ventilation passages 4A, 4B, 4C, each evaporator 5A,
Defrost sensors SA, SB, and SC, which are thermostats, are provided to detect the end of defrosting of 5B and 5C.

That is, in the freezing/refrigerating case, three cases 1A and 1 are operated by one compressor 8.
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 block 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 controls the defrosting sensors SA, SB, SC.
A control signal is sent to the power supply section 12 based on an input signal from the controller and a program stored in the memory. The power supply section 12 operates the compressor 8 and the solenoid valves 10A, 10B, 1 connected to the power supply section 12 based on this control signal.
0C, and supplies driving power to defrosting heaters HA1, HB1, HC1 and auxiliary heaters HA2, HB2, HC2, respectively.

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 T, and defrosting in each evaporator is performed when the defrosting timer T enters the defrosting mode.

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

If it is determined in step 1 that the defrost timer T is in the defrost mode, the counter for counting the number of defrosting units is reset, and each solenoid valve 10A,
10B and 10C are respectively closed to suppress the flow of refrigerant, and the operation of the compressor 8 is stopped. At the same time, each defrosting heater HA1, HB1, and HC1 is energized (step 2).

Then, it is determined whether or not the current defrosting is the first time (step 3).

If it is determined in step 3 that the current defrosting is the first time, it is first determined whether the defrost sensor SA has detected the end of defrosting (step 4), and if it has detected the end of defrosting, then Then, the defrosting heater HA1 is de-energized (step 5), 1 is added to the counter (step 6), and it is determined whether the counter value has reached 2 (step 7). If defrost sensor SA does not detect the end of defrost,
It is determined whether the current mode is the cooling mode (step 8).

Next, it is determined whether the defrost sensor SB detects the end of defrosting (step 9), and if it detects the end of defrosting, it stops energizing the defrost heater HB1 (step 10), and the counter 1 is added (step 11), and it is determined whether the counter value has reached 2 (step 12). If the defrosting 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 the defrost sensor SC detects the end of defrosting (step 14), and if it detects the end of defrosting, it stops energizing the defrost heater HC1 (step 15), and the counter 1 is added (step 16), and it is determined whether the counter value has reached 2 (step 17). Even 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. If it is determined at steps 8, 13, and 18 that the mode is not in the cooling mode, steps 9, 14, and 4 are entered, respectively, and if it is determined that the mode is in the cooling mode, the mode is entered in step 21, which will be described later.

When the counter value reaches 2 in steps 7, 12, and 17, in the illustrated example, if the defrost sensors SA and SB detect the end of defrosting, the evaporator at which defrosting has ended, that is, the evaporator Memorize 5C (step 19).

Then, the defrost timer T is forcibly returned to the cooling mode (step 20), and all remaining defrost heaters and auxiliary heaters, in this case defrost heater HC, are de-energized, and all evaporators 5A ,5
Solenoid valves 10A, 10B, 1 connected to B, 5C
0C is opened, the compressor 8 starts operating, and refrigerant is supplied to the evaporators 5A, 5B, and 5C to cool the interiors of the show cases 1A, 1B, and 1C (step 21), and the process returns to step 1.

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

If it is determined in step 1 that the defrost timer T is in the defrost mode, the counter for counting the number of defrosts completed is reset as in the first defrost, and each solenoid valve 10A, 10B, 10C is reset. are closed respectively to suppress the flow of refrigerant, and the operation of the compressor 8 is stopped. At the same time, each defrost heater HA1,
Electrify HB1 and HC1 respectively (step 2).

Then, it is determined again whether or not the current defrosting is the first time (step 3). Defrosting in this case is 2
Since this is the first defrosting, it is determined in step 3 that this is not the first defrosting.

Next, the defrosted evaporator 5C stored in step 19 is read out (step 22), and selected by the auxiliary heater HC2 corresponding to the evaporator 5C (step 23). Then, the selected auxiliary heater HC2 is energized (step 24).

Next, it is determined again whether or not the defrost sensor SA detects the end of defrosting (step 4), and if the end of defrosting is detected, the energization of the defrost heater HA1 is stopped (step 5). 1 is added to the counter (step 6), and it is determined whether the counter value has reached 2 (step 7). If the defrosting sensor SA does not detect the end of defrosting, it is determined whether the current mode is the cooling mode (step 8).

Next, it is determined whether the defrost sensor SB detects the end of defrosting (step 9), and if it detects the end of defrosting, it stops energizing the defrost heater HB1 (step 10), and the counter 1 is added (step 11), and it is determined whether the counter value has reached 2 (step 12). If the defrosting 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 the defrost sensor SC detects the end of defrosting (step 14), and if it detects the end of defrosting, the defrost heater HC1 and the auxiliary heater HC that were energized in step 24 are energized. is stopped (step 15), 1 is added to the counter (step 16), and it is determined whether the counter value has reached 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 become 2 in step 17, the process returns to step 4 and the detection status of each defrosting sensor is checked again. If it is determined in steps 8, 13, and 18 that the mode is not in the cooling mode, steps 9, 14, and 4 are entered, respectively, and if it is determined that the mode is in the cooling mode, the mode is entered in step 21, which will be described later.

In the second defrost in the illustrated example, the defrost sensor
SA and SC detect the end of defrosting and the counter value becomes 2.
Therefore, evaporator 5B is stored as an evaporator that has not yet been defrosted (step 19).

Then, the defrost timer T is forcibly returned to the cooling mode again (step 20), and all remaining defrost heaters and auxiliary heaters, that is, in this case, the defrost heater
At the same time as stopping the energization of HB1, the solenoid valves 10A, 1 connected to the evaporators 5A, 5B, 5C
0B and 10C are opened, the compressor 8 starts operating, and refrigerant is supplied to the evaporators 5A, 5B, and 5C to cool the interior of the case 1A, 1B, and 1C (step 21), and the process proceeds to step 1. return.

As described above, the evaporator of each case is defrosted. That is, in the embodiment, in the first defrosting, each defrosting heater HA1, HB1, HC1 is energized to defrost, and two of the three evaporators 5A,
When the defrosting of case 5B is completed first, all defrosting heaters HA1, HB1, and HC1 are de-energized, and refrigerant is supplied to all evaporators 5A, 5B, and 5C, and the case 1A, 1B, and 1C are Cooling is performed, and for the second defrosting, each defrost heater HA,
While energizing HB and HC, the evaporator 5 whose defrost has not been completely removed from the previous defrost
C has an auxiliary heater HC in addition to the defrosting heater HC1.
Since 2 is also energized, the heat generated by both the defrosting heater HC1 and the auxiliary heater HC2 is used to completely remove the frost on the evaporator 5C, including the residual amount from the first defrosting. becomes possible. For the third and subsequent defrosts, in the same way as the second defrost, both the defrost heater and the auxiliary heater are energized for the undefrosted evaporator whose frost was not completely removed during the previous defrost. It becomes possible to completely remove the frost on the evaporator, including the residual amount during defrosting.

In this way, according to the embodiment, all the defrosting heaters and auxiliary heaters are turned off at the stage when the defrosting of two of the three evaporators 5A, 5B, and 5C is completed during each defrosting operation. At the same time as stopping the power supply, all the solenoid valves are opened and the compressor starts operating to cool each show case.As shown in the temperature graph shown in Figure 1d, each show case
The internal temperatures of A, 1B, and 1C can be averaged around the defrosting end temperature. Therefore, during defrosting, the internal temperature of a specific storage case will not rise compared to the internal temperature of other storage cases, and the frozen/refrigerated products stored in that storage will not be unnecessarily heated. 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, in the second and subsequent defrosts, both the defrost heater and the auxiliary heater are energized for the undefrosted evaporator whose frost was not completely removed during the previous defrost, and the defrost heater and the auxiliary heater are energized. It is possible to completely remove the frost generated on the evaporator, including the residual amount from the previous defrosting process, by using the heat generated from both of the above. The cooling action is not hindered, and an evaporator with a large amount of frost can be defrosted quickly.

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.

(Effects of the Invention) As explained above, according to the present invention, when defrosting of a predetermined number of evaporators among the total number of evaporators is completed during each defrosting operation, all defrosting heaters and auxiliary heaters are energized. At the same time, refrigerant is supplied to all evaporators to cool each case, so the internal temperature of each case can be averaged around the defrosting end temperature. The internal temperature of a specific storage case will rise compared to the internal temperature of the storage case, and the frozen/refrigerated products stored in that storage will not be unnecessarily heated, and the cooling load will be reduced due to the rise in internal temperature. The cooling efficiency does not decrease when cooling is restarted due to an increase in the cooling efficiency.

In addition, in the second and subsequent defrosts, both the defrost heater and the auxiliary heater are energized for the undefrosted evaporator whose frost was not completely removed during the previous defrost, and the defrost heater and the auxiliary heater are energized. It is possible to completely melt and remove the frost generated on the evaporator, including the residual amount from the previous defrosting process, by using the heat generated by both of It does not remain and impede the cooling effect, and it is possible to quickly defrost an evaporator with a large amount of frost.

[Brief explanation of the drawing]

Figures 1a to 1d show embodiments of the present invention, in which Figure 1a is a cooling circuit diagram of a freezing/refrigerating case, Figure 1b is a configuration diagram of a defrosting control device, and Figure 1 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, HA1, HB1, HC1
... Defrost heater, HA2, HB2, HC2 ... Auxiliary 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 the defrost mode, all solenoid valves are closed, the compressor is stopped, and the defrost heater installed in each case is energized to restart the evaporator. In a defrosting control method for freezing and refrigerated storage cases that removes frost that occurs during the process, each evaporator is provided with an auxiliary heater, and each case is equipped with a defrost sensor that detects the completion of defrosting of the evaporator. When the frost timer enters defrost mode, all solenoid valves are closed and compressor operation is stopped, and the auxiliary equipment installed in each defrost heater and the evaporator at the end of defrosting during the previous defrosting operation is activated. Power is applied to the heater, and when each defrost sensor detects the end of defrosting of the evaporator after defrosting has started, the power to the defrost heater and auxiliary heater corresponding to that evaporator is stopped, and all evaporators are When defrosting of a predetermined number of evaporators is completed, the defrost timer is forcibly returned to cooling mode, all remaining defrost heaters and auxiliary heaters are de-energized, and all solenoid valves are opened to start compression. A defrosting control method for a freezing/refrigerating case, characterized in that the operation of the machine is started.