JP2002228338A - Defrost control method of freezing/refrigerating showcase - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a defrost control method of freezing/refrigerating showcase in which simultaneous conduction of a defrost heater and a refrigerating machine is not required at the time of defrost operation, a power supply facility is required to have a capacity dealing only with any one of the defrost heater or refrigerating machine having higher power consumption and thereby the capacity of power supply facility can be reduced. SOLUTION: A solenoid valve 9 for controlling refrigerant supply and a cooler connected with a defrost heater 11 are coupled with a refrigerating machine through refrigerant piping and on/off control of the solenoid valve 9 and the defrost heater 11 is effected by the output from a controller 12 at the time of defrost operation. In such a defrost control method of freezing/ refrigerating showcase, the defrost heater 11 is conducted after the controller 12 makes a decision that defrost operation has started and the refrigerating machine has stopped.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling defrosting of a refrigerated showcase.

[0002]

2. Description of the Related Art A refrigerated showcase 1 is, for example, shown in FIG.
As shown in FIG. 5, a showcase main body 1a having a U-shaped cross section formed of a heat insulating wall and having an opening 4 for entering and exiting a product in the front is partitioned by a duct plate, and divided into a product storage 2 and a cool air circulation duct 3, The cool air cooled by the refrigeration apparatus described later is blown out from the cool air circulation duct 3 to the opening 4, where a cool air curtain is formed to cool the products displayed in the product storage 2.

[0003] As is well known, the refrigerating apparatus is provided with a cooler 7 installed in a cool air circulation duct 3 in a refrigerating and refrigerated showcase 11.
Is connected to a refrigerator (compressor) 5 and a condenser 6 separately from the refrigerator-freezer showcase 1 by a refrigerant pipe 8 to form a refrigeration cycle, and a refrigerant pipe 8 on the refrigerant inlet side of the cooler 7. Has a solenoid valve 9 for controlling the supply of refrigerant to the cooler 7 to be stopped.
And a refrigerant pipe 8 on the refrigerant inlet side of the refrigerator 5.
Is connected to a low-voltage protection device 10. The low-pressure protection device 10 has a function of stopping the refrigerator 5 for a predetermined time after the low-pressure protection operation.

[0004] In the figure, reference numeral 11 denotes a defrost heater for removing frost adhering to the cooler 7.

[0005] Further, in the figure, reference numeral 12 denotes a controller using a microcomputer.
As shown in the control block diagram of FIG. 5, the central processing unit (C
PU) 13, a defrosting start determination input circuit 14 connected to the input side of the central processing unit 13, and an output circuit 15 connected to the output side of the central processing unit 13.

The input side of the defrost start determination input circuit 14 has a temperature sensor 16 for obtaining temperature data for determining the end of defrost or a time sensor for obtaining time data for determining the end of defrost. The external timer 17 is connected, and the solenoid valve 9 and the defrost heater 11 are connected to the output side of the output circuit 15.

In FIG. 4, reference numeral 18 denotes a power supply, which is connected to the defrost heater 11 and the low-pressure protection device 10 via a power supply line 19, respectively.

Next, the defrosting operation will be described with reference to the time chart of FIG. During the cooling operation, power is supplied to the refrigerator 5 and the refrigerator 5 is operated, and the solenoid valve 9 is opened and the refrigerator 5 is opened.
Is supplied to the cooler 7 through the refrigerant pipe 8,
The inside of the product storage 2 is cooled.

When the cooling operation time reaches a predetermined time by the output from the external timer 17 and the defrosting start time comes, or when the temperature of the cooler 7 is determined by the output from the temperature sensor 16 for detecting the temperature of the cooler 7. When the temperature has reached, the external timer 17 and the temperature sensor 16 output the signal to the defrost start determination input circuit 14. The defrost start determination input circuit 14 receives this input and outputs it to the central processing unit 13, and the output from the central processing unit 13 to the output circuit 15 is output from the output circuit 15 to the solenoid valve 9 and simultaneously closed, Defrost heater 11
Is also output to the switch and turned on. This starts the defrosting operation, and the temperature sensor 16 measures the temperature of the cooler 7 after the start of the defrosting, or the external timer 17 measures the defrosting time.

As described above, during the defrosting operation, the solenoid valve 9 is closed and the supply of the refrigerant to the cooler 7 is stopped.
On the other hand, at the start of the defrosting operation, the low pressure is reduced on the refrigerant circuit by closing the solenoid valve 9, and the pressure of the refrigerator 5 is reduced. Then, the low-pressure protection device 10 operates and the refrigerator 5 stops.

[0011]

The refrigerator 5 after the start of defrosting
As described above, after the solenoid valve 9 is closed and the defrost heater 11 is energized at the same time as described above, the low pressure is reduced, and the low pressure protection device 10 is operated.
After the start of defrosting, the power is supplied to both the defrost heater 11 and the refrigerator 5 until the refrigerator 5 stops.

For this reason, in this simultaneous energization state in which electric power is required for the defrost heater 11 and the refrigerator 5, the power supply equipment 18 needs to cover both power consumptions at the same time, so that the capacity of the power supply equipment 18 is increased. Is required.

An object of the present invention is to eliminate the disadvantages of the prior art, and it is not necessary to simultaneously energize both the defrost heater and the refrigerator during the defrost operation, and the capacity of the power supply equipment is reduced by the defrost heater or the refrigerator. It is an object of the present invention to provide a method for controlling the defrosting of a refrigerated showcase, which can reduce the capacity of a power supply equipment, in order to cope with a device that consumes more power.

[0014]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention firstly provides a refrigerator connected to a solenoid valve for controlling the supply of refrigerant and a defrost heater to a refrigerator through refrigerant piping. In the defrosting control method for a refrigerated showcase that is connected and performs on / off control of the electromagnetic valve and the defrosting heater during the defrosting operation with an output from the control device, the refrigerator is stopped after it is determined that defrosting has started. After it is determined that power has been supplied, the defrost heater is energized.

Therefore, the power supply to the defrosting heater is performed after the refrigerator is stopped, and the power is not supplied to the defrosting heater and the refrigerator at the same time, so that the power consumption does not increase after the start of the defrosting.

Secondly, the determination of the stop of the refrigerator is performed after a certain period of time has elapsed since the solenoid valve was closed.
The time from when the solenoid valve is closed to when the refrigerator is predicted to stop can be set in the control device in advance, and the energization of the defrost heater can be started after the refrigerator has reliably stopped.

Third, during the predetermined time, after the solenoid valve is closed, the low pressure of the refrigerant circuit is reduced, and the low pressure protection device connected between the cooler and the refrigerator is activated. By setting the time to be longer than the time until the machine stops, by setting the time in the control device, the defrost heater can be energized reliably after the refrigerator stops.

[0018]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is an explanatory view showing an embodiment of a method for controlling the defrosting of a refrigerator-freezer showcase of the present invention, and FIG.
Is a control block diagram of the same defrosting control method. The configuration of the refrigerating and refrigerated showcase shown in FIG. 1 and the entire configuration of the refrigerating apparatus are the same as those of the conventional example shown in FIG. Detailed description here is omitted.

In the same manner as in the prior art, a refrigerator 7 is installed in the cooling air circulation duct 3 in the refrigerator-freezer showcase 11 in which the defrosting control method of the present invention is carried out. A refrigerant pipe 8 is connected to a refrigerator (compressor) 5 and a condenser 6 provided separately from the refrigerated showcase 1 by a refrigerant pipe 8, thereby forming a refrigeration cycle. An electromagnetic valve 9 for controlling the stop of the supply of the refrigerant to the cooler 7 is provided, and a low-pressure protection device 10 is connected to the refrigerant pipe 8 on the refrigerant inlet side of the refrigerator 5. The low-pressure protection device 10 has a function of stopping the refrigerator 5 for a predetermined time after the low-pressure protection operation.

Referring to FIG. 2, the control block of the defrosting control will be described. As in the conventional case, reference numeral 12 denotes a controller using a microcomputer.
It comprises a central processing unit (CPU) 13, a defrosting start input circuit 14 connected to the input side of the central processing unit 13, and an output circuit 15 connected to the output side of the central processing unit 13.

A temperature sensor 16 for obtaining temperature data for judging the end of defrosting, or a time sensor for obtaining temperature data for judging the end of defrosting is provided on the input side of the defrosting start judgment input circuit 14. The external timer 17 is connected, and the solenoid valve 9 and the defrost heater 11 are connected to the output side of the output circuit 15.

In FIG. 1, reference numeral 18 denotes a power supply, which is connected to the defrost heater 11 and the low-pressure protection device 10 via a power supply line 19, respectively.

In the present invention, in addition to the control block having such a configuration, a delay time setting input circuit 20 is connected to the central processing unit 13. The delay time setting input circuit 20 outputs the signal to close the solenoid valve 9 from the central processing unit 13 via the output circuit 15 to the solenoid valve 9 and then outputs the signal to start the energization to the defrost heater 11. A fixed delay time for delaying is set.

The length of the delay time is determined, for example, by outputting a signal for closing the solenoid valve 9 from the central processing unit 13 to the solenoid valve 9 via the output circuit 15 and closing the solenoid valve 9 after the solenoid valve 9 is closed. In addition, the low pressure is reduced, the low pressure protection device 10 connected between the cooler 7 and the refrigerator 5 is activated, and the time is set to be longer than the time until the refrigerator 5 stops after that.

Next, a defrosting control method according to the present invention will be described with reference to FIG. During the cooling operation, power is supplied to the refrigerator 5 and the refrigerator 5 is operated, the solenoid valve 9 is opened, the refrigerant from the refrigerator 5 is supplied to the cooler 7 through the refrigerant pipe 8, and the inside of the product storage 2 is cooled. Have been.

When the cooling operation time reaches a predetermined time by the output from the external timer 17 and the defrosting start time comes, or when the temperature of the cooler 7 is determined by the output from the temperature sensor 16 for detecting the temperature of the cooler 7. When the temperature has reached, the external timer 17 and the temperature sensor 16 output the signal to the defrost start determination input circuit 14. The defrost start judgment input circuit 14 receives this input and outputs it to the central processing unit 13. The output from the central processing unit 13 to the output circuit 15 is output from the output circuit 15 to the solenoid valve 9 and closed.

Even if such a close signal is output to the solenoid valve 9, during this time, the central processing unit 13 and the output circuit 15 receive the input from the delay time setting input circuit 20 to send the signal from the output circuit 15 to the defrost heater 11. No defrost start signal is output.

Therefore, during the time set as the delay time, power is not supplied to the defrost heater 11 and the power supply equipment 1
From 8, power is supplied only to the refrigerator 5, so that only the power consumed by the refrigerator 5 is sufficient.

When the solenoid valve 9 is closed, the supply of the refrigerant to the cooler 7 is stopped, and the low pressure in the refrigerant circuit decreases, and the pressure in the refrigerator 5 decreases. As a result, the low-pressure protection device 10 operates and the refrigerator 5 stops.

After the refrigerator 5 is stopped,
When the delay time set in the delay time setting input circuit 20 elapses and the count is counted up, the count value is output from the central processing unit 13 to the defrost heater 11 via the output circuit 15 for the first time, and the power is supplied to this. Then, the defrost heater 11 is turned on.

When the defrost heater 11 is turned on, the refrigerator 5 has already been stopped, so the power supply 18
Is not supplied, but is supplied only to the defrost heater 11. Therefore, the supply power is only required to be consumed by the defrost heater 11.

When the defrost heater 11 is turned on after the refrigerator 5 is stopped in this way, in the above-described embodiment, the determination of the stop of the refrigerator 5 is made as a factor for determining the timing of turning on the defrost heater 11. It is assumed that a certain period of time has elapsed since the solenoid valve 9 was closed, and the change in pressure on the refrigerant pipe 8 was used. However, the present invention is not limited to this. It is also possible to employ an electrical means for detecting the electric signal, inputting the electric signal to the controller 12, and outputting an ON signal to the defrost heater 11 based on the input signal.

After the solenoid valve 9 is closed, the defrost heater 1
It takes time for 1 to turn on, but during this time it is slight and the defrosting efficiency does not decrease.

[0034]

As described above, the method for controlling defrosting of a freezer and refrigeration showcase according to the present invention firstly uses a cooling device in which a solenoid valve for controlling supply of refrigerant and a defrosting heater are connected. In a defrosting control method for a refrigerated refrigerated showcase, which is connected to a refrigerator by a pipe and performs on / off control of the electromagnetic valve and the defrosting heater at the time of defrosting operation with an output from a control device, after it is determined that defrosting is started. Then, after it is determined that the refrigerator has stopped, power is supplied to the defrost heater.

Therefore, the power supply to the defrosting heater is performed after the refrigerator is stopped, the power is not supplied to the defrosting heater and the refrigerator at the same time, and the power consumption does not increase after the start of the defrosting.

Second, the determination of the stop of the refrigerator is made after a certain period of time has elapsed since the solenoid valve was closed.
The time from when the solenoid valve is closed to when the refrigerator is predicted to stop can be set in the control device in advance, and the energization of the defrost heater can be started after the refrigerator has reliably stopped.

Third, during the certain period of time, after the solenoid valve is closed, the low pressure of the refrigerant circuit is reduced, and the low pressure protection connected between the cooler and the refrigerator is activated. Is longer than the time it takes to stop,
By setting such a time in the control device, it is possible to reliably supply electricity to the defrost heater after the refrigerator has stopped.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an embodiment of a method for controlling defrosting of a freezer and refrigerated showcase according to the present invention.

FIG. 2 is a control block diagram showing an embodiment of a method for controlling defrosting of a freezing and refrigerated showcase of the present invention.

FIG. 3 is a time chart showing an embodiment of a method for controlling defrosting of a refrigerator-freezer showcase of the present invention.

FIG. 4 is an explanatory diagram of a conventional method for controlling defrosting of a refrigerator-freezer showcase.

FIG. 5 is a control block diagram of a conventional method for controlling defrosting of a refrigerator-freezer showcase.

FIG. 6 is a time chart of a conventional method for controlling defrosting of a refrigerator-freezer showcase.

[Explanation of symbols]

1 ... Refrigerated showcase 1a ...
Showcase main body 2 ... Product storage 3 ... Cold air circulation duct 4 ... Opening 5 ... Refrigerator 6 ... Condenser 7 ... Cooler 8 ... Refrigerant pipe 9 ... Solenoid valve 10 ...
Low pressure protection device 11 Defrost heater 12 Controller 13
Central processing unit 14 ... Defrosting start judgment input circuit 15 ...
Output circuit 16 Temperature sensor 17 External timer 18
Power supply equipment 19: Power supply line 20: Delay time setting input circuit

Claims (3)

[Claims] An on-off control of the electromagnetic valve and the defrost heater during a defrosting operation by connecting a cooler to which a solenoid valve for controlling the supply of the refrigerant and a defrost heater are connected to a refrigerator through a refrigerant pipe. In the method of controlling defrosting of a refrigerated showcase, which performs the output from the control device, the control device determines that the defrost has started, and then determines that the refrigerator has stopped, and then energizes the defrost heater. Defrosting control method for refrigerated showcases. 2. The method for controlling defrosting of a refrigerator-freezer showcase according to claim 1, wherein the determination as to whether or not the refrigerator is stopped is made when a predetermined time has elapsed since the solenoid valve was closed. 3. The method according to claim 1, wherein the low pressure of the refrigerant circuit is reduced after the solenoid valve is closed, and the low pressure protection device connected between the cooler and the refrigerator operates for the predetermined time. 2. The method according to claim 1, wherein the time is set to be longer than the time until the stoppage.