JPH0674941B2 - Defrost control method for refrigeration cycle - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for controlling defrosting in a refrigerating cycle such as a refrigerator-freezer.

[Conventional technology]

FIG. 6 is a sectional view of a defrosting device for a refrigerator / freezer shown in Japanese Utility Model Laid-Open No. 60-65582, which is an example of a conventional defrosting control method for a refrigerating cycle, and FIG. 7 shows a basic refrigerating cycle. It is a circuit diagram. In the figure, (1) is a refrigerator box, (2)
Is a blast fan, (3) is an evaporator, (4) is an evaporator (3)
A liquid reservoir tank provided at the outlet, (5) is an evaporator (3)
End plate for supporting the (6) is the evaporator (3)
A glass tube heater attached below, (7) a umbrella provided directly above the glass tube heater (6), (8) a toy provided at the bottom of the evaporator chamber, and (11) an end plate (5). ) A guide for heat convection attached to the lower part, (12) is a compressor, (13) is a condenser, (14) is a decompressor, and (15) is a refrigerant conduit.

Next, the operation will be described. First, the compressor (12), the condenser (13), the pressure reducer (14), and the evaporator (3) are connected to the refrigerant pipeline (1
When the refrigeration cycle connected sequentially by 5) is operated, the evaporator (3) becomes extremely low temperature. Then, air in the refrigerator is applied to the cryogenic evaporator (3) to cause heat exchange to cool the air, and the cooled air is forcibly convected by the blower fan (2) to freeze the refrigerator. It is sent again to the inside of the refrigerator to cool the inside. At this time, the moisture contained in the air in the refrigerator adheres to the surfaces of the accelerator (3) and the liquid storage tank (4) as frost during heat exchange. Then, the frost forms a layer between the evaporator (3) trying to exchange heat and the air and hinders the heat exchange. Therefore, the normal freezer-refrigerator regularly performs defrosting operation.

Since the defrosting operation is an operation of defrosting and removing the frost on the surface of the evaporator (3) and the liquid storage tank (4) by heating, the cold air of the evaporator (3) during the freezing operation is removed. Since it is contrary to the work that occurs, that is, heat removal, the normal refrigeration operation is stopped, that is, the compressor (12) is temporarily stopped and then the defrosting operation is performed, and after the defrosting operation is completed, the compressor (1
2) was started and the refrigeration operation was performed.

In the defrosting operation, the glass tube heater (6) is energized after the compressor (12) is stopped, and the glass tube heater (6) is driven to generate heat and heat nearby air. The heated air naturally convects and moves upward to defrost by exchanging heat with the frost on the surface of the evaporator (3). Also, part of the heated air is
The heat generated by the glass tube heater (6) causes the heat convection guide (11) bent inward to move up to the liquid storage tank (4) side to defrost the surface of the liquid storage tank.

When defrosting is completed, the temperature detected by the defrosting sensor attached to the surface of the liquid storage tank is 10 to 15 ° C above the melting point of frost.
It is judged by having reached.

[Problems to be solved by the invention]

In the conventional defrosting method of the refrigeration cycle, since defrosting is simply performed by radiant heat emitted from the heater, defrosting near the heater is removed in a relatively short time, but it is heated when the distance from the heater increases. The defrosting time of the upper part of the evaporator and the liquid storage tank far from the heater is drastically decreased because the amount of heat of the air is drastically reduced, and all the heat generated from the heater cannot be used only for defrosting. Since it is impossible, the longer the heating time of the heater,
There is a problem that the frost in the place away from the heater is thawed and the heat of the heater is transferred to the inside of the chamber to be cooled by the cool air of the evaporator, which raises the temperature inside the chamber.

The present invention has been made to solve the above problems, and quickly and surely transfers the amount of heat generated by the heater to the portion of the evaporator away from the heater and the liquid storage tank.
It is an object of the present invention to obtain a defrosting control method for a refrigeration cycle that can minimize defrosting in a short time while minimizing the heat influence on the inside of the refrigerator to be cooled.

[Means for solving problems]

A defrosting control method for a refrigeration cycle according to the first aspect of the present invention,
A heater is provided near the refrigerant inflow side of the evaporator, and the compressor is operated for a short time at predetermined time intervals during the defrosting operation by the heater.

Further, the second invention provides a refrigerant control valve between the condenser and the pressure reducer, and a check valve between the evaporator and the compressor, and normally opens and closes in synchronization with ON-OFF of the compressor. The control valve is opened during the defrosting operation regardless of the operation of the compressor.

[Action]

In the defrosting control method of the refrigeration cycle according to the first aspect of the present invention, the evaporator refrigerant in the vicinity of the heater, which is locally heated by the heat energy of the heater, is gradually moved to the evaporator away from the heater and the liquid storage tank by the compressor. Then, the moved refrigerant serves as a new heat source in each part to melt the frost outside the pipe wall in the vicinity of the refrigerant, and the frost melted in the vicinity of the heater is not further overheated and evaporated.
The inside of the refrigerator does not get very humid.

The second aspect of the invention is to defrost the refrigerator provided with the refrigerant control valve and the check valve during the defrosting operation of the refrigerator by always opening the refrigerant control valve without synchronizing with ON-OFF of the compressor. The time can be shortened.

〔Example〕

The present invention improves the defrosting ability by utilizing the stopped refrigeration cycle during the heating defrosting by the heater.

A first invention of a defrosting control method for a refrigerating cycle will be described with reference to FIG. 1 and FIG.

In FIG. 1, (1) is a refrigerator box, (2) is a fan fan, (3) is an evaporator, (4) is a liquid storage tank provided on the outlet side of the evaporator (3), and (6) is evaporation. A glass tube heater attached to the bottom of the vessel (3), (7) a umbrella attached directly above the glass tube heater (6), (8) a toy provided at the bottom of the evaporator chamber, and (9) a drain. Tube, (10)
Is a defrost sensor attached to the surface of the liquid storage tank (4). FIG. 2 is a time chart showing the control of the compressor and the glass tube heater during the defrosting operation of the refrigerator / freezer, and t shows the instantaneous operating time of the compressor during the defrosting operation. a is the compressor instantaneous operation stop temperature, and b is the defrosting completion temperature.

The normal cooling operation is the same as the conventional refrigerator / freezer, in which the inside of the refrigerator is cooled by the operation of the refrigeration cycle, and the defrosting operation is performed periodically for the same reason as in the conventional refrigerator / freezer.

Next, this defrosting control will be described with reference to the time chart of FIG.

First, when the defrosting operation starts, the glass tube heater (6)
Power is supplied to the glass tube heater (6) and heat is generated. At the same time, the compressor (12) in the refrigeration cycle
The normal continuous drive or the control operation based on the internal temperature is switched to the instantaneous operation for a short time t at a predetermined interval T.

Then, the intermittent operation of the compressor (12) is continued until the temperature sensed by the defrost sensor (10) reaches point a where it is determined that the frost on the surface of the liquid storage tank (4) has melted. Until the temperature detected by the defrost sensor (10) reaches point a, the pressure inside the evaporator is a saturation pressure of 0 ° C at which the frost melts, and even if the compressor (12) momentarily operates, the pressure due to the compressor suction The refrigerant warmed in the lower part of the evaporator (3) near the glass tube heater (6) with almost no lowering of the evaporation temperature is cooled by the glass tube heater (6) at the outlet side of the evaporator (3). It can be moved to a remote location. Due to the movement of the heated refrigerant, the upper part of the evaporator (3) apart from the glass tube heater (6), which is difficult to receive the thermal energy of the glass tube heater (6) by natural convection, and the liquid storage tank (4)
The refrigerant inside the pipe can be transferred to the inside of the pipe, and the refrigerant inside the pipe becomes a new heat source at that portion, and frost is defrosted from the inside of the pipe, so the evaporator (3) separated from the glass tube heater (6) Frost on the upper part and the surface of the liquid storage tank (4) can be quickly thawed.

The defrosting operation of this freezer-refrigerator is performed until the temperature detected by the defrosting sensor (10) reaches point b (about 10 ° C.), which is higher than the temperature at which frost melts.

This is because the melted frost has time to flow into the water drop from the evaporator (3) to the toy (8) and further to the drain pipe (9). This is to prevent ice from remaining on the surface. Since the internal pressure and temperature of the evaporator (3) increase between the points a and b until the frost melts and flows, if the compressor is operated instantaneously at this time, the pressure drop due to the suction of the compressor will occur. As a result, the evaporation temperature drops for a moment, affecting the temperature sensed by the defrost sensor (10). Therefore, when the compressor (12) is operated instantaneously, the defrost sensor (1
It is preferable to operate up to the a point (0) of the sensing temperature (1 to 3 ° C.), and this control method can shorten the defrosting time.

Since the frost generated in the evaporator during the refrigeration cycle is created by the cold air generated by the refrigerant flowing in the evaporator, if the refrigerant is used as the heat source, the heat source must be sent to a place with frost. There is no need to worry about heating unnecessary parts or the interior of the refrigerator until the frost disappears, and when the frost disappears, it stops using the refrigerant as a heat source.
Since the heat generation of the glass tube heater is stopped, there is no concern about the influence of heat caused by using the refrigerant as the heat source.

Here, the time T during which the compressor (12) is stopped is the time required for the refrigerant in the evaporator (3) near the glass tube heater (6) to absorb heat from the glass tube heater (6). , It is the time to radiate the heat energy absorbed by the refrigerant in the evaporator (3) and the liquid storage tank (4) away from the glass tube heater (6) to the frost outside the tube wall.

Therefore, this time T should be set so that the heat energy of the refrigerant after absorbing heat after defrosting of the evaporator (3) in the vicinity of the glass tube heater (6) is not released after passing through the frosting section. For example, heat radiation other than frost can be completely prevented.

In addition, the time t during which the compressor (12) operates instantaneously is the time to send out the heat-absorbed refrigerant to the position where there is frost in the vicinity of the glass tube heater (6). It is the time to draw in the vicinity of the heater, and the time away from the glass tube heater (6) is the time to draw in the refrigerant that has absorbed heat.

Therefore, at this time t, if the refrigerant that has absorbed heat at the same time is set so as to be completely replaced with the refrigerant that has not yet absorbed heat, uniform defrosting without unevenness in total frost can be performed.

In the above embodiment, the refrigerator having no refrigerant control valve in the refrigerant circuit is described, but as shown in FIG.
3) Refrigerant control valve (1) between outlet and pressure reducer (14) inlet
6) is provided and a check valve (17) is provided between the outlet of the evaporator (3) and the inlet of the compressor (12). As shown in the time chart of FIG. 3, the compressor is turned on during normal cooling operation. It is suitable for refrigerators that open and close the refrigerant control valve (16) in synchronism with ON-OFF of the compressor (12) in order to reduce OFF loss, and by the glass tube heater (6) as shown in the fourth time chart. During defrosting operation, regardless of whether the compressor (12) is on or off, the refrigerant pure control valve (16) is always open and the defrosting sensor (10) starts when defrosting starts.
By operating the compressor (12) for a certain period of time (T) for a short period of time (t) until the temperature sensed by the sensor becomes equal to or higher than the melting temperature of frost (1 to 3 ° C.) a, the same effect as in the above-described embodiment is obtained. Can be obtained.

〔The invention's effect〕

The defrosting control method for the refrigeration cycle according to the first aspect of the invention is
Since a heater was provided near the refrigerant inflow side of the evaporator and the compressor was operated for a short time at predetermined time intervals during the defrosting operation by this heater, the heat energy of the heater caused a local heating near the heater. Evaporator The refrigerant is gradually and forcibly moved by the compressor to the evaporator and the liquid storage tank away from the heater, and the moved refrigerant becomes a new heat source in each part and melts the frost outside the pipe wall near the refrigerant. Therefore, the frost on the part away from the heater can be surely removed in a short time.

Moreover, the temperature rise near the heater can be suppressed by the inflow of new refrigerant, the frost melted near the heater will not be overheated and will not evaporate, the inside of the refrigerator will not become high humidity, and it will be restarted after defrosting is completed. At this time, frost is not likely to be formed on the evaporator and the liquid storage tank again, new frost formation can be prevented, and therefore, an efficient operation can be realized.

Further, the refrigerant heated by the heater flows back to the condenser and does not radiate heat in the condenser, but radiates heat in the evaporator, so that the heat of the heater does not escape to the outside of the refrigerator.

Further, in the second invention, when the refrigerant control valve is provided in the refrigerator in which the refrigerant control valve is provided between the condenser and the pressure reducer and the check valve is provided between the evaporator and the compressor, the compressor is turned on during defrosting operation. The same effect as that of the first aspect of the invention is achieved by fixing the open state without synchronizing with the OFF operation.

[Brief description of drawings]

FIG. 1 is a front view of a refrigerator-freezer showing an embodiment of a defrosting control method for a refrigeration cycle of the first invention, FIG. 2 is a time chart showing defrosting control in the embodiment of FIG. 1, and FIG.
FIG. 4 is a refrigerant circuit diagram of one embodiment of the second invention, and FIG.
Time chart showing the defrosting control of the embodiment shown in FIG.
FIG. 6 is a time chart of the control during normal operation of FIG. 3, FIG. 6 is a front view of a refrigerator showing a conventional defroster, and FIG. 7 is a basic refrigerant circuit diagram. In the figure, (1) is a refrigerator box, (2) is a blower fan,
(3) is an evaporator, (4) is a liquid storage tank, (5) is an end plate, (6) is a glass tube heater, (7) is a bulkhead, (8) is a toy, (9) is a drain tube, ( 10) is a defrost sensor, (11) is a guide for heat convection, (12) is a compressor,
(13) is a condenser, (14) is a pressure reducer, (15) is a refrigerant line,
(16) is a refrigerant control valve, and (17) is a check valve. The same reference numerals in the drawings indicate the same or corresponding parts.

Claims (2)

[Claims] 1. A defrosting sensor is provided in the evaporator or the liquid reservoir tank of a refrigeration cycle in which a compressor, a condenser, a decompressor, an evaporator, and a liquid reservoir tank are sequentially connected by a refrigerating pipeline. A heater is provided in the vicinity of the refrigerant inflow side, and the heater is driven to operate the compressor for a short time at predetermined time intervals from the start of defrosting until the temperature detected by the defrosting sensor is equal to or higher than the melting point of frost. A defrosting control method for a refrigeration cycle, comprising: 2. A defrosting sensor is provided on the evaporator or the liquid reservoir tank of a refrigeration cycle in which a compressor, a condenser, a decompressor, an evaporator, and a liquid reservoir tank are sequentially connected by a refrigerating pipeline. Is provided in the vicinity of the refrigerant inflow side, a refrigerant control valve is provided in the refrigerant pipeline between the condenser and the decompressor, and the refrigerant is evaporated from the compressor in the refrigerant pipeline between the evaporator and the compressor. A check valve that stops the flow of refrigerant to the vessel is provided, and the heater is driven to operate the compressor for a short time at predetermined time intervals from the start of defrosting until the temperature detected by the defrosting sensor is equal to or higher than the melting point of frost. And during this time the compressor
A defrosting control method for a refrigerating cycle, characterized in that the refrigerant control valve is always kept open regardless of whether it is ON or OFF.