JPS6326837B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic defrosting system in a fan type refrigerator.

The above-mentioned fan-type refrigerator is configured to use a fan to send cold air from the cooler to a refrigerator compartment or a low-temperature refrigerator compartment (hereinafter referred to as a freezer compartment).
It is configured as shown in the figure. That is, a heat pump type cooling circuit is adopted, and a cooler 1 consisting of an evaporator is placed in a cooling chamber 4 equipped with a fan 3 at the inside upper part of the refrigerator body 2, and a compressor 5 which is a driving device for the cooler 1 is installed. are installed at the outer lower part of the refrigerator main body 2, and the inside of the main body 2 is partitioned by a partition wall 6 into an upper freezing compartment 7 and a lower refrigerating compartment 8, and these two compartments and the cooling compartment 4 are connected to cooling passages 9, 10 , 11. In the figure, 3a is a fan motor, 12
is a damper, and the freezer compartment side passage 9 and the refrigerator compartment side passage 1
The damper 12 is provided at the outlet of the communication tube 13 that communicates with the refrigerator compartment 8, and is configured by a thermostat 14 and its interlocking rod 15 to close the outlet when the room temperature of the refrigerator compartment 8 falls to a certain low temperature.

In the above refrigerator, while the compressor 5 is operating, the refrigerant in the cooling circuit evaporates and absorbs heat in the cooler 1, so the inside of the cooling chamber 4 is cooled. Then, in the passage 9, a portion is sucked into the cooling chamber 4. The remaining portion is sent from the communication tube 13 into the refrigerator compartment 8 through the passage 11 on the refrigerator compartment 8 side, and then circulated as if sucked into the cooling compartment 4 from the passage 10. This circulation cools and dehumidifies the air that has been humidified and warmed by the opening and closing of the doors of the freezer compartment 7 and refrigerator compartment 8, food, etc., and the dehumidified water forms frost on the surface of the cooler.

By the way, conventionally, the automatic defrosting in the fan type refrigerator was performed by the defrosting electric circuit shown in FIG. That is, the motor 17 of the timer 16 for compressor operation time integration is connected in parallel to each of the power source, compressor 5, and fan motor 3a, and the defrost heater 18 is connected in parallel to the timer motor 17, and the power source is connected to the power source. On the other hand, a timer switch 20 is provided which turns off the compressor 5 and turns on the heater 18 when a control thermostat 19 and a timer 16 installed in the freezing room have integrated the operating time of the compressor 5 to a set value. Note that 21 is a door switch, 22 is a temperature fuse, and 23 is a differential thermostat.

In the above case, the control thermostat 19 detects the temperature of the freezer compartment, turns on and off the compressor 5, and also turns the timer motor 17 on and off to integrate the operating time of the compressor 5, and the operation time of the compressor 5 is accumulated over a certain period of time. When you reach
The switch 20 was switched to the heater side to defrost the cooler.

However, this method has the disadvantage that electricity is wasted because defrosting is performed until the cooler reaches a constant temperature regardless of whether or not there is frost on the cooler.

The present invention has been made in view of the above-mentioned drawbacks of the conventional technology, and aims to provide a system in which defrosting is performed only when the amount of dehumidification by the cooler increases to a set value.

The present invention will be explained in detail below. First, to explain the steam diagram in Figure 3, the temperature at point A is T1℃,
The amount of dehumidification W (Kg) when air with relative humidity α% is cooled to temperature T2 at point B is determined by the following equation.

W=G(x1-x2)・H...(1) However, G: Air flow rate (Kg/h) x1: Absolute humidity before cooling (Kg/Kg) x2: Absolute humidity after cooling (Kg/Kg) H: Time (h) By the way, the absolute humidity before cooling and after cooling x1,
x2 can be calculated using the following formulas.

x1=f(T1, α) …(2) x2=f(T2,1) …(3) However, f( ): vapor diagram function T1: Air temperature before cooling (℃) T2: Air temperature after cooling (℃) α: Relative humidity before cooling Therefore, equation (1) becomes the following equation.

W=G{f(T1,α)-f(T2,1)}・H...(4) In a refrigerator-freezer equipped with a refrigerator compartment and a low-temperature refrigerator compartment (freezer compartment), the air before cooling is There is indoor air and frozen indoor air, each of which is cooled to a temperature close to that of the cooler, so the amount of dehumidification in the cooler is determined by the following equation.

W=[Gr{f(Tr,αr) −f(Te,1)}+Gf{f(Tf,αf) −f(Te,1)}]・H…(5) However, Gr: Air flow rate (Kg/h) Tr: Refrigerator room temperature (°C) Te: Cooler temperature (°C) αr: Refrigerator room relative humidity Gf: Air flow rate to the freezer compartment (Kg/h) Tf: Freezer room temperature (°C) ) αf: Relative humidity of the freezer compartment In the above equation (5), Gr and Gf are determined at the design stage as the capacity of the fan. The temperature and humidity of the air conditioner and the temperature of the cooler are detected, and a control circuit calculates the amount of dehumidification from these, and when the amount of dehumidification increases to a set value, the cooling operation is switched to the defrosting operation. It is something.

Next, an embodiment of the present invention will be described based on the electrical circuit diagram of FIG. 4. The fan motor 3a, the compressor 5, and the defrost heater 18 are connected in parallel to the power supply, and the contact a on the defrosting operation side and the contact a on the cooling operation side are connected in parallel to the power supply. A defrosting relay having a movable contact c that switches between contacts b and a relay having a movable contact d that switches between starting and stopping the cooling operation are provided to convert the temperatures of the freezer compartment, refrigerator compartment, and cooler into electrical signals. Sensor Cf, Cr, Ce
and humidity sensors Df and Dr that convert the relative humidity of the freezer and refrigerator compartments into electrical signals, and a control circuit E that controls the movable contacts c and d of the relay based on these signals. This control circuit E is constructed as follows. That is, the amount of dehumidification W within a unit time is calculated using equation (5), this is sampled only during the operating time of the compressor 5 and fan motor 3a, that is, the cooling operating time, W is integrated, and the value increases up to the set value. Then, the movable contact c of the relay is switched to the contact a side to start defrosting, and at the same time the integrated value of W is set to zero, and then when the cooler temperature reaches a certain value by the temperature sensor Ce of the cooler, the defrost relay is activated. The configuration is such that the contact c returns to the contact b side, enters cooling operation, and starts integrating the amount of dehumidification.

Therefore, in FIG. 4 above, the control circuit E
The temperature Tr, Tf,
Te is detected by humidity sensors Dr, Df to detect humidity αr, αf, and based on Gr, Gf and vapor diagram function f( ) set at the time of fan design, W within unit time is calculated.
is calculated using equation (5), and only the operating time of the compressor 5 and fan motor 3a, that is, the cooling operating time, is sampled, W is integrated, and when the value increases to the set value, the movable contact c of the relay is switched to the contact point. Switch to the a side, start defrosting, and at the same time make the integrated value of W zero, then when the cooler temperature reaches a certain value by the cooler temperature sensor Ce, return the movable contact c of the defrost relay to the contact b side. , enters cooling operation and starts integrating the amount of dehumidification.

As is clear from the above description, the present invention is a fan-type refrigerator in which cold air from the cooler is sent to the refrigerator compartment by air blowing from a fan. This invention relates to a defrosting method for a refrigerator characterized in that when the temperature increases to a certain value, the cooling operation is switched to the defrosting operation.

W=G{f(Tr,α)−f(Te,1)}・H Where, G: Amount of air blown to the refrigerator compartment f( ): Steam diagram function Tr: Refrigerator compartment temperature Te: Cooler temperature α: Relative humidity of the refrigerator compartment H: Operating time of the cooler Therefore, in the method of the present invention, defrosting can be automatically performed according to the amount of dehumidification W by cooling operation, that is, the amount of frost on the cooler, so that cooling is not as difficult as in the conventional cooling. Compared to the method of defrosting according to the operating time, it is possible to eliminate waste of electric power. Note that, apart from the present invention, a method of defrosting by detecting the amount of frost with an optical sensor may be considered, but with this method, the amount of frost over the entire cooler would be uneven due to usage conditions such as opening and closing of the door. However, the method of the present invention is not affected by such uneven frosting, and can be used with various structures. It has excellent advantages such as being compatible with all refrigerators.

[Brief explanation of drawings]

Fig. 1 is a longitudinal sectional view of a refrigerator-freezer for explaining the present invention, Fig. 2 is an electric circuit diagram of a conventional system, Fig. 3 is a steam diagram according to the system of the present invention, and Fig. 4 is an electric circuit diagram of the same. . 1: Cooler, 2: Refrigerator body, 3: Fan, 3
a: fan motor, 4: cooling room, 5: compressor,
7: Freezer room (low temperature refrigerator room), 8: Refrigerator room, 18:
Defrost heater, Cf, Cr, Ce: Temperature sensor, Df,
Dr: temperature sensor, E: control circuit, b, d: movable contact.

Claims (1)

[Scope of Claims] 1. In a fan-type refrigerator in which cold air from the cooler is sent to the refrigerator compartment by air blowing from a fan, the amount of dehumidification W due to cooling is calculated using the following formula, and when the amount of dehumidification W increases to a set value, , a refrigerator defrosting method characterized by switching cooling operation to defrosting operation. W=G{f(Tr,α)-f(Te,1)}・H Where, G: Amount of air blown to the refrigerator compartment (Kg/h) f( ): Steam diagram function Tr: Refrigerator compartment temperature (°C ) Te: Cooler temperature (℃) α: Relative humidity of the refrigerator H: Cooler operating time (h) W: Dehumidification amount (Kg)