JPH0463312B2 - - 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. Defrosting heaters are installed in each of the defrosting heaters, and during defrosting, all solenoid valves are closed, the compressor is stopped, and cooling is stopped, and each defrosting heater is energized to generate heat, which is generated in the evaporator. Removes frost by melting it.

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 intermittently 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 Sea Yorkes C, which takes the longest time to defrost, the internal temperature of Shoe Cases A and B, which finished defrosting earlier, rose significantly above 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.
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 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 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. After the defrosting is started, when each defrosting sensor detects the end of defrosting of the evaporator, the defrosting heater corresponding to the evaporator is de-energized;
When the defrosting of a predetermined number of evaporators among all evaporators is completed, the defrost timer is forcibly returned to cooling mode, the remaining defrost heaters are de-energized, and all solenoid valves are opened to start compression. At the same time as starting the machine operation, at the next defrosting time, when the defrost timer enters the defrosting mode, all solenoid valves are closed and the compressor operation is stopped. A feature of the present invention is that the defrosting heaters of a predetermined number of evaporators that have finished frosting are energized after a predetermined time delay than other defrosting heaters.

(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.

During the first defrost after cooling operation has started, when the defrost timer enters defrost mode, all solenoid valves are closed to suppress the flow of refrigerant and the compressor Operation will be stopped. and,
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 out of the total number of evaporators is completed, the defrost timer is forcibly returned to the cooling mode, power supply to all remaining defrost heaters is stopped, and all electromagnetic The valves are opened and the compressor starts operating, and refrigerant is supplied to each evaporator to cool each case.

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 that was not completely removed during the previous defrosting is energized for a predetermined period of time earlier than the static elimination heater of the evaporator that has finished defrosting during the previous defrosting. Utilizing 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. 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.

An evaporator 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 power 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 block diagram of a defrosting control device according to the present invention, in which numeral 11 denotes a control section consisting of a microprocessor, memory, etc., and numeral 12 denotes a power supply section. The control unit 11 controls the defrosting sensors SA, SB, SC.
A control signal is sent to the power supply unit 12 based on an input signal from the power supply unit 12 and a program stored in the memory. The power supply unit 12 operates based on this control signal.
compressor 8, solenoid valves 10A, 10B,
10C and the defrosting heaters HA, HB, and HC, 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 set in advance 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 timer T1 is not in the defrost mode, the process returns to step 1.

If it is determined in step 1 that the defrosting timer T1 is in the defrosting 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 defrosting, the counter for counting the number of defrosting completed units is reset, and each solenoid valve 10A, 10
B and 10C are closed respectively to control the flow of refrigerant,
The operation of the compressor 8 is stopped. At the same time, each defrosting heater HA, HB, and HC is energized (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 the defrosting has been completed, Then, the defrosting heater HA 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). defrost sensor
If the 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 the defrost sensor SB has detected the end of defrosting (step 9), and if it has detected the end of defrosting, it stops energizing the defrost heater HB (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 HC (step 15), and sets the counter to 1 is added (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 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, when the defrost sensors SA and SB detect the end of defrosting, the evaporator that has completed defrosting at that point, that is, the evaporator The evaporator 5A and evaporator 5B are memorized (step 19).

Then, the defrost timer T1 is forcibly returned to the cooling mode (step 20), and the remaining defrost heaters, that is, the defrost heater HC, are de-energized and connected to all the evaporators 5A, 5B, and 5C. The solenoid valves 10A, 10B, 10C are opened, the compressor 8 starts operating, and the refrigerant is supplied to the evaporators 5A, 5B, 5C to cool the interior of the case 1A, 1B, 1C ( Step 21), return to step 1.

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

If it is determined in step 1 that the defrost timer T1 is in the defrost mode, then it is 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 the counter for counting the number of defrosting units is reset, and each electrode valve 10A, 10B, 10C is turned on. The compressor 8 is closed to restrict the flow of refrigerant and the operation of the compressor 8 is stopped (step 22).

Next, the defrosted evaporators 5A and 5B stored in step 19 are read out (step 23), and from this information, the defrosted evaporators 5C whose defrost was not completely removed during the previous defrosting are read out (step 23). Defrosting heater HC is selected (step 24). Then, the selected defrosting heater HC is energized (step
twenty five).

Next, the delay timer T2 is started (step 26), and the time t2 set by the delay timer T2 is
It is monitored whether or not the period has elapsed (step 27). Then, when the delay timer T2 times up, the evaporator 5 is stored again in step 19 and the defrosting is completed.
A and 5B are read out (step 28), and defrost heaters HA and HB corresponding to the evaporators 5A and 5B are selected (step 29). Then, the selected defrosting heaters HA and HB are energized (step 30).

Then, as with the first defrost, each defrost sensor
Check the detection status of SA, SB, and SC, and step 7.
When the counter value reaches 2 at steps 12 and 17, the evaporator whose defrosting has been completed at that time is memorized (step 19). During the second defrosting in the illustrated example,
Since the defrosting sensors SA and SC detect the end of defrosting and the value of the counter becomes 2, the evaporators 5A and 5C are now stored as the evaporators whose defrosting has ended.

In other words, during the second defrosting, the defrosting 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 defrosting heater HC of the evaporator 5C, which has not yet finished defrosting, is energized after a predetermined time t2 set by the defrosting delay timer T2,
In other words, the defrost heater HC of the evaporator 5C whose frost was not completely removed during the first defrost is supplied with the defrost heater HA and HB of the evaporator 5A and 5B whose defrost has been completed during the first defrost. The evaporator is energized for a predetermined period of time t2, so it is possible to use this energization time to completely remove the frost that has formed on the evaporator, including the residual amount from the first defrosting. . 3
Similarly to the second defrosting process, the defrosting heater of the evaporator whose defrost was not completely removed during the previous defrosting operation will be marked The predetermined time t2 is longer than the defrosting heater of the evaporator.
The current is applied earlier, and it becomes possible to completely melt and remove the frost that has formed on the evaporator, including the residual amount from the previous defrosting operation.

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,
When two of the three evaporators have finished defrosting, the remaining defrost heaters are de-energized, all solenoid valves are opened, the compressor starts operating, and each evaporator is turned off. Because it is cooling,
As shown in the temperature graph shown in FIG. 1d, the internal temperatures of each of the cases 1A, 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, during the second and subsequent defrosting operations, the defrosting heaters of the undefrosted evaporators whose defrost was not completely removed during the previous defrosting operation will be replaced by the defrosting heaters of the evaporators that were defrosted during the previous defrosting operation. The predetermined time t2 is longer than the defrosting heater of the evaporator.
This makes it possible to completely remove the frost that has formed on the evaporator, including the residual amount from the previous defrosting process, by using this energization time. A large amount of frost does not remain and the cooling effect 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, 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, the remaining defrosting heaters are de-energized and refrigerant is supplied to all evaporators to cool each case. 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 stored frozen/refrigerated products 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 reduced when cooling is restarted.

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

[Brief explanation of the drawing]

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 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 the defrosting control method for freezing and refrigerating case cases, each case is equipped with a defrost sensor that detects the end of defrosting of the evaporator. When the sensor detects the end of defrosting of an evaporator, it stops energizing the defrost heater corresponding to the evaporator, and forces the defrost timer when defrosting of a predetermined number of evaporators out of all the evaporators is completed. At the next defrost, the defrost timer returns to the cooling mode, stops energizing the remaining defrost heaters, opens all solenoid valves, and starts compressor operation. When this happens, all solenoid valves are closed and compressor operation is stopped, and the defrost heaters of the predetermined number of evaporators that have finished defrosting during the previous defrost operation are A defrosting control method for a freezing/refrigerating case, characterized in that power is turned on after a predetermined time delay.