JPH0120710B2 - - Google Patents

Description

Detailed Description of the Invention The present invention relates to a defrosting device in which a dew pan equipped with a heating source is placed directly below an evaporator, and its purpose is to shorten the defrosting time of the evaporator and to The purpose is to eliminate frost residue.

Conventional techniques for placing a dew pan equipped with a heating source directly below the evaporator and forcibly heating the dew pan together with the evaporator during defrosting include the cooling device described in Japanese Utility Model Publication No. 18785/1985; There is a defrosting device for a cooler described in Publication No. 40-8935.

The above-mentioned former conventional technology has a configuration that has a first and second defrosting circuit for intensively heating an evaporator in the initial stage of defrosting, and a dew pan in a later stage, respectively. Since the capacity of the compressor itself is constant, the hot gas from the compressor will not be divided into the evaporator and the dew pan even if it is a centralized heating, and the amount of hot gas circulated per hour will not change. Both the defrosting time and the draining time for the dew pan are short, and during seasons with a large amount of frost such as the rainy season, there is a problem in that frost remains on the evaporator, resulting in the need to lengthen the defrosting time. was invited.

In addition, in the latter prior art, a part of the side pipe that guides high-temperature gas refrigerant called hot gas to the evaporator during defrosting is used as a saucer defrosting tube that serves as a heating source for the dew tray; A push-up valve is provided between the defrost pipe and the inlet of the evaporator, and during defrosting, the high-temperature gas refrigerant in the saucer defrost pipe is first raised to a certain pressure by the push-up valve, and then the high-temperature gas refrigerant is guided to the evaporator. Since the dew pan is heated before the evaporator, the amount of heat of the high-temperature gas refrigerant flowing into the evaporator is smaller than before passing through the dew pan, which lengthens the defrosting time of the evaporator. Although the drainage process of the saucer was improved, the overall defrosting time became longer.

The present invention has been made to solve the above problems.

Examples of the present invention will be described below with reference to the drawings.
Figure 1 shows the refrigerant circuit, 1 is a refrigerant compressor, SV ₁
is a three-way solenoid valve for flow path switching, 2 is an air-cooled condenser with a blower CF, 3 is a liquid receiver, 4 is a temperature-type expansion valve, 5 is an air-cooled evaporator with a blower EF, and 6 is an air-cooled condenser with a blower EF. A liquid separator separates these refrigeration parts into a high pressure gas pipe 7, a high pressure liquid pipe 8, a low pressure liquid pipe 9 and a low pressure gas pipe 10.
The side pipe 12 having the check valve 11 is connected to the three-way solenoid valve SV ₁ at one end, and the other end is connected to the low pressure liquid pipe 9 to form the cooling cycle shown by the solid line arrow. Form the defrost cycle shown by the arrow. Reference numeral 13 denotes a dew pan disposed directly below the evaporator 5, and is equipped with a heat source 14 such as a defrosting heater that is energized before the start of defrosting the evaporator 5.

FIG. 2 shows the control circuit of the defrosting device, R,
S and T are power supply terminals, and CM is contact 52Ca of the electromagnetic switch for the compressor and overload relay, which will be described later.
The compressor motor 52C is connected to the power supply terminal via OLR ₁ and OLR ₂ , and 52C is a parallel circuit of a thermostat TH for regulating the temperature inside the refrigerator and the first positive contact 1Xa ₁ of the first auxiliary relay, which will be described later. The compressor electromagnetic switch is connected between the overload relays via the compressor, and these components constitute a control circuit for the compressor 1. DT is the defrosting timer connected between the power terminals R and T, 1X is the second positive contact 1Xa ₂ for self-holding, the thermostat AOTH for defrosting recovery and the safety device HTH provided in the evaporator 5. The first auxiliary relay is connected between the power terminals R and T via the heating source 14 and connected in parallel, and DTH is a three-way solenoid valve.
A defrosting start thermostat, DTa, which is connected in parallel to the first auxiliary relay with SV ₁ , is provided in the dew pan 13, and is opened and closed depending on the temperature of the heating source 14.
is the contact point of the defrost timer connected in parallel to the defrost timer DT and in series to the defrost start thermostat DTH, 2X is the second auxiliary relay connected in parallel to the three-way solenoid valve SV ₁ , and EFM is the contact point of the defrost timer connected in parallel to the defrost timer DT and in series to the defrost start thermostat DTH. A series circuit is formed with the first reverse contact 2Xb ₁ of the second auxiliary relay, and the first
Auxiliary relay 1X and the second positive contact 1 of this relay
evaporator blower motor in parallel with Xa ₂ ;
CFM is the second reverse contact 2Xb ₂ of the second auxiliary relay
The condenser blower motor is connected between the power terminals R and T via the condenser, and these parts constitute a defrosting control circuit.

In this configuration, the compressor 1 is operated when the thermostat TH for regulating the internal temperature is closed, forming a cooling cycle as shown by the solid line arrow in Figure 1, and is stopped when the thermostat TH is opened, resulting in a so-called thermocycle operation. Become. As the cooling cycle progresses, the defrosting time comes and the timer contact DTa is closed for a certain period of time by a signal from the defrosting timer DT. As the timer contact closes, the heating source 14 is energized, and at the same time the first
Auxiliary relay 1X is energized and its first positive contact 1
Close Xa ₁ and turn on the thermostat to adjust the internal temperature.
The compressor 1 is operated regardless of whether TH is opened or closed, and the second tangent contact 1Xa ₂ is closed to maintain self-holding. When the temperature of the dew pan 13 heated by the heating source 14 reaches a predetermined value, for example, 3°C or higher, the defrosting start thermostat DTH closes, and the three-way solenoid valve SV ₁ is energized to direct the flow direction of the high-temperature gas refrigerant to the high-pressure gas pipe. 7 to the side pipe 12 to flow the high temperature gas refrigerant to the evaporator 5. At the same time, the second auxiliary relay 2X is energized and opens its first and second reverse contacts 2Xb ₁ and 2xb ₂ for the evaporator and condenser. Stop the operation of both blowers EF and CF, and start the defrosting cycle shown by the chain arrow in Figure 1.

Timer contact DTa as the defrost cycle progresses
is opened and the temperature of the evaporator 5 reaches the upper limit set value, e.g. 10℃.
When the defrost return thermostat AOTH opens and the first auxiliary relay 1X becomes de-energized, both its first and second contacts 1Xa ₁ and 1Xa ₂ open and the compressor 1
At the same time, the heating source 14 is de-energized, the three-way solenoid valve SV ₁ switches the flow direction of the high-temperature gas refrigerant to the high-pressure gas pipe 7, and the self-holding is released. The second auxiliary relay 2X is de-energized and its first and second opposite contacts 2Xb ₁ and 2Xb ₂ are closed. The condenser blower CF is operated by closing the second reverse contact 2Xb ₂ , and the evaporator blower EF is operated by the defrosting return thermostat AOTH, which closes when the temperature of the evaporator 5 reaches the lower limit set value, for example -1°C. is,
Return to cooling cycle.

That is, the cooling cycle, defrosting cycle, and cooling cycle are carried out as shown in the time chart shown in FIG.

According to this configuration, the heating source 14 generates heat and the dew pan 13 is heated by the operation of the defrosting timer DT, and when the temperature of the dew pan 13 rises to a predetermined temperature, the thermos for starting defrosting is activated. Since Tatsuto DTH operates and defrosts the evaporator 5, the dew pan 1
Since defrosting of the evaporator 5 using the high-temperature gas refrigerant can be started after the temperature of the evaporator 3 reaches a temperature sufficient to melt the frost from the evaporator 5, the heating of the dew pan 13 can follow the heating of the evaporator 5. The evaporator 5 is cooled and the evaporator 5 is cooled from the start of heating the dew pan 13 to the start of defrosting of the evaporator 5. The ambient temperature around the vessel 5 is kept low;
A cooling effect can be applied until just before the start of defrosting, and the frost adhering to the evaporator 5 can be gradually melted by the radiant heat from the dew pan 13.

In addition, since the defrost return thermostat AOTH, which detects the temperature of the evaporator 5, simultaneously stops the heating of the dew pan 13 by the heating source 14 and the heating of the evaporator 5 by the high-temperature gas refrigerant, the frost in the evaporator 5 is completely removed. Defrosting can be performed to prevent unnecessary heating.

Therefore, according to the present invention described above, before defrosting the evaporator, the dew pan is heated while cooling the evaporator, and defrosting of the evaporator is started based on the temperature of the dew pan. Until the start of defrosting of the evaporator, the evaporator performs a cooling action and the dew pan can be heated while suppressing the rise in ambient temperature, so the defrosting time of the evaporator can be shortened and the dew pan can be heated. Drain treatment becomes better.

[Brief explanation of drawings]

The drawings show an embodiment of the defrosting device of the present invention, in which FIG. 1 is a refrigerant circuit diagram, FIG. 2 is a control circuit diagram, and FIG. 3 is a time chart explaining the cycle. 5... Evaporator, 13... Dew pan, 14... Heating source, DTH... Thermostat for starting defrosting.

Claims (1)

[Claims] 1. A heating source that is provided on a dew pan located directly below the evaporator and heats the dew pan based on a signal from a defrosting timer, and a temperature of the dew pan heated by this heating source is set to a predetermined value. a defrosting start thermostat that stops the cooling action of the evaporator and starts the defrosting action when the temperature of the evaporator reaches a predetermined value; A defrosting device comprising a defrosting recovery thermostat that stops the heating action of the heating source.