JPH0463311B2 - - Google Patents

Abstract

PURPOSE:To defrost the frost growth remaining on the evaporators by such a manner that when there are evaporators which are yet to complete the defrosting while other evaporators have completed the defrosting, the cooling medium is not supplied to the unfinished evaporators for a certain time period after the power supply to the defrosting heater is stopped. CONSTITUTION:When defrosting sensors SA, SB detect the completion of the defrosting, the defrosting timer is forcibly returned to the cooling mode, and the power supply to the remaining defrosting heater HC is stopped. Only solenoid valves 10A, 10B that are connected to the evaporators 5A, 5B which have completed the defrosting are opened, and, at the same time, a compressor 8 is started to supply the cooling medium to the evaporators 5A, 5B to cool the interior space of the showcases 1A, 1B. The cooling medium is not supplied to the evaporator 5C for the showcase 1C which has yet to complete the defrosting for a certain time period after the power supply to the defrosting heater HC is stopped. By using such time, the frost remaining on the evaporator HC is melted away by the remaining heat and the atmospheric temperature.

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 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.
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 warehouse. 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 each 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. 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, The defrost timer is forcibly returned to cooling mode, all defrost heaters are de-energized, only the solenoid valve connected to the evaporator that has finished defrosting is opened, and the compressor starts operating. , and the remaining solenoid valves are opened after a predetermined period of time has elapsed since defrosting was started.

(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, and the flow of refrigerant is controlled so that the operation of the compressor is stopped. Then, 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. Then, when the defrosting of a predetermined number of evaporators among all the evaporators is completed, the defrost timer is forcibly returned to the cooling mode, the power supply to all the defrosting heaters is stopped, and the defrosting is completed first. Only the solenoid valves connected to a predetermined number of evaporators are opened, and
The operation of the compressor is started and refrigerant is supplied to the evaporator to cool the interior of the show case.

After a predetermined period of time has elapsed since defrosting has started, the remaining defrost heaters are de-energized, the remaining solenoid valves are opened, and refrigerant is supplied to the evaporator to cool the remaining interior of the show case. .

In other words, when the defrosting of a predetermined number of evaporators is completed, the remaining evaporators that have not been defrosted will continue to be operated for a while until the predetermined time elapses even after the defrost heater is de-energized. Since no refrigerant is supplied, it is possible to use this time to melt and remove the frost remaining in the evaporator using residual heat and atmospheric temperature.

(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 each of the ventilation passages 4A,
Defrost sensors SA, SB, and SC, which are thermostats, are provided in the evaporators 4B 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 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 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.
Supply driving power to 0C and defrosting heaters HA, HB, and HC, respectively. 13 is a sales detection means for detecting whether the show case is in a sales state or a sales suspension state;
The sales detection means 13 detects the illumination of the show case.
It consists of a sensor that detects ON/OFF, a switch that can be manually operated, etc., and sends different signals to the control section 11 when sales are on sale and when sales are stopped.

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 illustrated embodiment is an example in which different defrosting methods are used at the time of sale and at the time of suspension of sale, and particularly shows an example in which the present invention is adopted for defrosting at the time of sale.

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), and if it is in the defrost mode, it is determined whether the show case is ready for sale or not. (Step 2).

If it is determined in step 2 that it is time to sell, the timer T2 for monitoring the defrosting time and the counter for the defrosting end number coefficient are reset, and each solenoid valve 10A, 10B, 10C is closed. The flow of refrigerant is suppressed and the operation of the compressor 8 is stopped.
At the same time, each defrost heater HA, HB, HC
are energized, respectively, and timer T2 is started (step 3).

Next, first, it is determined whether or not the defrost sensor SA detects the end of defrosting (step 4), and if it detects the end of defrosting, it stops energizing the defrost heater HA (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 or not (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 or not (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 35, which will be described later.

When the counter value reaches 2, for example, when the defrost sensors SA and SB detect the end of defrosting, the defrost timer T1 is forcibly returned to the cooling mode (step 19), and the remaining defrost time is The frost heater HC is de-energized, only the solenoid valves 10A and 10B connected to the evaporators 5A and 5B that have been defrosted are opened, and the compressor 8 is started to operate.
Supply refrigerant to A and 5B and switch cases 1A and 1.
The inside of refrigerator B is cooled (step 20).

Next, it is determined whether the remaining defrost sensor SC detects the end of defrosting (step 21), and if it detects the end of defrosting, the remaining solenoid valve 10C is opened to supply refrigerant to the evaporator 5C. Supply remaining case 1
The inside of the refrigerator C is cooled (step 22), and the process returns to step 1.

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

As described above, defrosting is carried out at the time of sale, for example during the day. That is, in the embodiment, when the defrosting of two of the three evaporators 5A and 5B is completed, the power supply to all the defrosting heaters HA, HB, and HC is stopped, and the two evaporators that finished defrosting first are turned off. evaporators 5A, 5B
At the same time, the evaporator 5C of the case 1C, which has not yet been defrosted, is supplied with refrigerant to cool the cases 1A and 1B until a predetermined period of time has passed even after the defrost heater HC is de-energized. Refrigerant is not supplied for a while, and this time is used to melt and remove frost remaining in the evaporator HC using residual heat and atmospheric temperature.

If it is determined in step 2 that it is time to stop selling, each solenoid valve 10A, 10B, 10C is closed to suppress the flow of refrigerant, the operation of the compressor 8 is stopped, and each defrosting heater is closed. HA, HB,
Power is applied to each HC (step 24).

Next, determine whether or not the defrost mode is on (step
25) If the defrost mode is selected, it is determined whether the defrost sensor SA has detected the end of defrosting (step
26) When the end of defrosting is detected, the defrost heater is activated.
Stop powering the HA (step 27).

Next, it is determined whether or not the defrost sensor SB has detected the end of defrosting (step 28), and if it has detected the end of defrosting, the energization of the defrost heater HB is stopped (step 29).

Next, the defrost sensor SC determines whether or not the end of defrosting has been detected (step 30), and if it has detected the end of defrosting, the defrost heater HC is de-energized (step 31).

If each defrosting sensor does not detect the end of defrosting in steps 26, 28, and 30, it is determined in steps 32, 33, and 34 whether or not the defrosting mode is active.

If it is determined in steps 25, 32, 33, and 34 that the mode is not defrost mode but cooling mode, power to all defrost heaters HA, HB, and HC is stopped (in the illustrated example, the power supply to all defrost heaters HA, HB, and HC is stopped before entering cooling mode). At the same time, all the solenoid valves 10A, 10B, and 10C are opened, and the compressor 8 is started to supply refrigerant to the evaporators 5A, 5B, and 5C. Then, the interiors of the show cases 1A, 1B, and 1C are cooled down (step 35), and the process returns to step 1.

As described above, defrosting is performed when sales are stopped, for example at night. This defrosting at the time of suspension of sales is different from the defrosting at the time of sales mentioned above, and defrosting is carried out until the frost that has formed on the three evaporators 5A, 5B, and 5C is completely removed. ing.

In this way, according to the embodiment, in defrosting at the time of sale, all the defrosting heaters HA, HB,
The power supply to the HC is stopped, and refrigerant is supplied to the two evaporators 5A and 5B that have finished defrosting first to start cooling the case 1A and 1B, and the evaporation of the case 1C that has not yet been defrosted is started. Refrigerant is not supplied to the evaporator 5C for a while until a predetermined period of time has passed even after the defrosting heater HC is de-energized, and this time is used to remove the frost remaining in the evaporator 5C. Since it is melted and removed using residual heat and atmospheric temperature, the frost that has formed on the evaporators 5A and 5B can be completely removed without causing a rise in the temperature inside the refrigerator. 5C
Even frost that has formed on the refrigerator can be efficiently removed by melting it with residual heat and atmospheric temperature without causing an increase in the temperature inside the refrigerator. Therefore, as shown in the temperature graph shown in FIG.
Since the internal temperatures of A and 1B can be averaged around the defrosting end temperature, the internal temperature of a specific case will rise compared to the other cases during defrosting, and 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 inside the refrigerator and the cooling efficiency is not decreased 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, although different defrosting methods are used at the time of sale and at the time of suspension of sale, defrosting may be carried out throughout the day using the same defrosting method as at the time of sale employing the present invention.

(Effects of the Invention) As explained above, according to the present invention, when the defrosting of a predetermined number of evaporators among the total number of evaporators is completed, the evaporators of the show case that have not been defrosted are defrosted. Refrigerant is not supplied for a while until a predetermined period of time has passed even after the heater has been de-energized.
Using this time, the frost remaining on the evaporator is melted and removed by residual heat and atmospheric temperature, so the frost that has formed on the evaporator, which does not take much time to defrost, is removed by raising the temperature inside the refrigerator. In addition to being able to completely remove frost that has formed on the evaporator, which takes the longest time to defrost, it can be efficiently removed by melting it with residual heat and atmospheric temperature without causing a rise in internal temperature. . Therefore, the internal temperature of the case where defrosting takes the longest time and the case where defrosting ends quickly can be averaged around the defrosting end temperature. The temperature rises compared to the internal temperature of other storage cases, and the frozen and
The refrigerated product is not heated unnecessarily, and the cooling load is not increased due to a rise in the temperature inside the warehouse and the cooling efficiency is not reduced 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... Showcase, 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 completion of defrosting of the evaporator. When this is detected, the defrost heater corresponding to the evaporator is de-energized, and when a predetermined number of the evaporators out of all the evaporators have been defrosted, the defrost timer is forcibly returned to the cooling mode. All defrosting heaters are de-energized, only the solenoid valves connected to the evaporators that have been defrosted are opened, compressor operation is started, and the remaining A defrosting control method for a freezing/refrigerating case, characterized in that a solenoid valve is opened.