JPH04347482A - Defrosting method of freezing and refrigerating showcase - Google Patents

Abstract

PURPOSE:To make wiring work between a heater controlling relay provided in a showcase and a machine room, in which a refrigerating device is installed, unnecessary when defrosting is effected by the heater in a separately installed showcase. CONSTITUTION:A device is constituted of a plurality of freezing and refrigerating showcases 1a-1n, equipped with a defrosting heater, and one set of refrigerating device while respective freezing and refrigerating showcases 1a-1n are provided with a timer 8 to conduct electric current through the defrosting heater by the output of said timers 8 after stopping the operation of the freezing device.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for defrosting a so-called separate type freezer/refrigerator showcase, in which a plurality of freezer/refrigerator showcases are cooled by one separate refrigeration device.

0002

[Prior art] For multiple frozen and refrigerated showcases,
In a separate type refrigeration/refrigeration showcase, the compressor and condenser of the refrigeration system are placed separately in a machine room outside the showcase, and the cooler installed in each showcase is operated for cooling by this compressor, etc. Although there are various methods for removing frost attached to the cooler provided in each showcase, there is a method in which a defrosting heater is provided for each showcase.

[0003] In this defrosting method using a defrosting heater, in order to prevent an increase in current during defrosting operation, the operation of the refrigeration equipment is stopped and then the defrosting heater is energized. . FIG. 2 shows an example of a defrosting circuit, in which reference numerals 1a to 1n indicate frozen and refrigerated showcases, and each of the frozen and refrigerated showcases 1a to 1n includes a defrosting heater built into each of the showcases 1a to 1n. A relay 2 (not shown) is provided. Further, reference numeral 4 in the figure indicates a liquid solenoid valve provided in the middle of a refrigerant circuit that supplies refrigerant to the coolers installed in each of the showcases 1a to 1n.
is connected in series to the temperature regulator 3 provided in each of the showcases 1a to 1n.

Reference numeral 9 in the figure indicates a machine room in which a compressor and the like of the refrigeration system are installed, and the machine room 9 includes electromagnetic contacts for on/off control of the refrigeration system for cooling each of the showcases 1a to 1n. The electromagnetic contactor 6, the defrost timer 5, the relay 2 switched by the contact 5a of the timer 5, and the liquid solenoid valve 4 are connected to the power supply 10. connected in parallel. In the figure, 7 is a low pressure switch that detects the pressure on the low pressure side of the refrigerant circuit, and is connected in series to the electromagnetic contactor 6. Further, a normally closed contact 6a of an electromagnetic contactor 6 is connected in series to the relay 2 that controls the defrosting heater.

Next, the operation will be explained. All the showcases 1a to 1n operate in the same way, so here we will explain the showcase 1a as an example.The defrost timer 5 is set in advance with the defrost start time, and when the power supply 10 is turned on, the electromagnetic contact is activated. Since the defrost timer 6 is energized and the contact 5a of the defrost timer 5 is switched to the liquid solenoid valve 4 side, the liquid solenoid valve 4 is also energized and opens, and the refrigerant in the refrigerant circuit flows into the showcase 1a. The water is supplied to the cooler installed in the air conditioner, and cooling operation begins. At this time, the contacts 6a of the electromagnetic contactor 6 are separated by the excitation of the electromagnetic contactor 6, so that the relay 2 is not energized and the defrosting heater is not energized and generates no heat. At the same time, the defrost timer 5 is energized and starts counting.

As the cooling operation progresses, the amount of frost on the cooler increases and the cooling capacity decreases, but the defrost timer 5 counts up and the defrost start time set in the defrost timer 5 is reached. When this happens, the contact 5a of the defrost timer 5 is switched to the defrost heater relay 2 side. As a result, the energization to the liquid electromagnetic valve 4 is cut off and the liquid electromagnetic valve 4 is closed, but the refrigeration system continues to operate because the electromagnetic contactor 6 continues to be energized. Further, since the contact 6a of the electromagnetic contactor 6 also maintains an open state, the relay 2 is not energized.

[0007] In this way, when the refrigeration system is operated with the liquid electromagnetic valve 4 of the refrigerant circuit closed and the refrigerant in the refrigerant circuit is recovered, the pressure on the low pressure side of the refrigerant circuit decreases. This pressure drop is detected by the low pressure switch 7, and when it is activated and its contacts open, for example, several minutes later, the power to the electromagnetic contactor 6 is cut off and becomes non-excited, and its contacts 6a return and close. As a result, the refrigeration equipment stops and the contact 6a
The relay 2 connected in series to is energized, the defrosting heater is energized and generates heat, and defrosting of the cooler starts.

[0008]

[Problem to be Solved by the Invention] Since the on/off control of the defrosting heater relay provided in each showcase is performed by turning on/off the contacts of the electromagnetic contactor provided in the machine room, the defrosting heater It was necessary to connect the relay and the contact of the electromagnetic contactor, which required wiring work between the showcase and the machine room, and the work of installing the showcase was time-consuming.

An object of the present invention is to eliminate the disadvantages of the conventional example, and to eliminate the need for wiring work between the heater relay of each showcase and the machine room when defrosting is performed using a heater in a separate freezer/refrigerator showcase. To provide a defrosting method for a frozen/refrigerated showcase that allows easy installation of the showcase.

0010

[Means for Solving the Problems] In order to achieve the above object, the present invention comprises a plurality of frozen/refrigerated showcases equipped with defrosting heaters and one refrigeration device, and each frozen/refrigerated showcase is provided with a timer. The gist of the invention is to energize the defrosting heater based on the output from the timer after the operation of the refrigeration system is stopped.

[0011]

According to the present invention, after the operation of the refrigeration system is stopped, the defrosting heater is energized by the output from the timer provided for each freezer/refrigerator showcase, and defrosting is started. Therefore, wiring work between each showcase and the machine room in which the refrigeration equipment is installed in order to control on/off of the defrosting heater is not required.

0012

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a defrosting control circuit diagram in which the defrosting method for a refrigerated showcase of the present invention is implemented, and the same components as in the conventional example shown in FIG. 2 are given the same reference numerals. In the present invention, as in the past, a defrosting heater (not shown) and a relay 2 for controlling the defrosting heater are incorporated in each of the plurality of freezer/refrigerating showcases 1a to 1n, and each showcase
A liquid electromagnetic valve 4 connected in series to a temperature regulator 3 is provided in the middle of a refrigerant circuit that supplies refrigerant to the coolers installed at points a to 1n. In addition, each showcase 1a to 1n is provided in the machine room 10.
an electromagnetic contactor 6 that controls on/off the refrigeration system for cooling the refrigerator, and a motor-type defrost timer 5 that sets the defrost start time.
A low pressure switch 7 for detecting the pressure on the low pressure side of the refrigerant circuit is connected in series to the electromagnetic contactor 6.

In the freezer/refrigerator showcases 1a to 1n, a timer 8 connected in parallel to a relay 2 is provided for each showcase 1a to 1n, and a contact 8a of the timer 8 is connected to the relay 2 in series. For the power supply 10, a defrost timer 5, an electromagnetic contactor 6, a circuit of a liquid solenoid valve 4 which is switched by a contact 5a of the timer 5, a timer 8 and a relay 2 are connected to the power supply 10.
and the parallel circuit are connected in series.

Next, the operation will be explained. The operations of the plurality of showcases 1a to 1n are all the same, so here we will explain using the showcase 1a as an example.The defrosting timer 5 has a defrosting start time set in advance, and the defrosting timer 5 is set in advance. After the liquid solenoid valve 4 is closed, the timer 8
A time longer than the time until the low pressure switch 7 is activated is set as the defrosting start delay time.

When the power supply 10 is turned on, the electromagnetic contactor 6 is energized, and since the contact 5a of the defrosting timer 5 has been switched to the liquid solenoid valve 4 side, the liquid solenoid valve 4 is also energized and opens. The refrigerant in the refrigerant circuit is supplied to the cooler installed in the showcase 1a, and cooling operation starts. At the same time, the defrost timer 5 is also energized and starts counting.

When the defrost timer 5 counts up and reaches the defrost start time set in the defrost timer 5, the contact 5a of the defrost timer 5 switches to the side of the parallel connection circuit between the timer 8 and the relay 2. . As a result, the energization to the liquid solenoid valve 4 is cut off and the liquid solenoid valve 4 is closed, but the electromagnetic contactor 6 continues to be energized, so that the refrigeration system continues to operate. Then, timer 8 starts counting.

When the refrigeration system continues to operate with the liquid electromagnetic valve 4 in the refrigerant circuit closed in this manner, the pressure on the low pressure side of the refrigerant circuit decreases, and this pressure decrease is detected by the low pressure switch 7. , the contact opens. As a result, the power supply to the electromagnetic contactor 6 is cut off, and the refrigeration system stops operating. Thereafter, the timer 8 counts up, and when the contact 8a of the timer 8 closes, the relay 2 is energized, the defrosting heater is energized and generates heat, and defrosting of the cooler starts.

[0018]

[Effects of the Invention] As described above, in the defrosting method for a refrigerated/freezer showcase of the present invention, a timer for controlling the relay of the defrosting heater is provided in the showcase in a separate showcase. This eliminates the need for wiring work between the showcase and the machine room, simplifying the work of installing the showcase.

[Brief explanation of drawings]

FIG. 1 is a refrigerant circuit diagram in which the defrosting method for a refrigerated showcase of the present invention is implemented.

FIG. 2 is a refrigerant circuit diagram showing a conventional example.

[Explanation of symbols]

1a~1n...Frozen refrigerated showcase 2...Relay 3...Temperature controller 4...Liquid solenoid valve 5...Defrost timer 5a...Contact 6...Magnetic contactor 6a...Contact 7...Low pressure switch 8...Timer 8a...Contact 9...Machine room 10...Power supply

Claims (1)

[Claims] Claim 1: Consisting of a plurality of freezing/refrigerating showcases equipped with defrosting heaters and one freezing device, each freezing/refrigerating showcase is provided with a timer, and after the freezing device stops operating,
A defrosting method for a frozen/refrigerated showcase, characterized in that a defrosting heater is energized by an output from the timer.