Defrost apparatus of refrigerator

Abstract

The present invention discloses a defrost apparatus of a refrigerator which can defrost an evaporator by a defrost heater, when moisture of the ambient air of the evaporator is frozen on the surface of the evaporator. The defrost apparatus of the refrigerator includes a pair of evaporators and a pair of defrost heaters to selectively defrost the pair of evaporators. A path varying means for guiding air flow is installed near the pair of evaporators. The air is not supplied to the defrosted evaporator, for performing the defrosting operation. The air is supplied to the non-defrosted evaporator, for performing the cooling operation. As a result, the defrosting operation is efficiently performed, and the temperature does not sharply increase in freezing and refrigerating chambers, so that the food can be maintained fresh for an extended period of time.

Description

TECHNICAL FIELD

The present invention relates to a defrost apparatus of a refrigerator which can perform a defrosting operation by using a defrost heater and controlling inflow of the ambient air, when moisture of the ambient air of an evaporator is frozen on the surface of the evaporator.

BACKGROUND ART

In general, refrigerators are classified into a direct cooling type refrigerator and an indirect cooling type refrigerator according to a cooling method. In the direct cooling type refrigerator, evaporators are installed on inner walls of a freezing chamber and a refrigerating chamber. The cool air generated around the evaporators is naturally convected to cool the freezing chamber and the refrigerating chamber. In the indirect cooling type refrigerator, an evaporator is installed in inner walls of a freezing chamber, and a fan is installed on a cool air circulation path. The cool air generated around the evaporator is forcibly sent by the fan to cool the freezing chamber and the refrigerating chamber.

In the indirect cooling type refrigerator, when the fan is operated, the air of the freezing chamber and the refrigerating chamber directly passes through the evaporator, and then is circulated. Therefore, moisture of the air of the freezing chamber and the refrigerating chamber is frozen on the surface of the evaporator, thereby deteriorating the heat exchange performance. In order to solve the above problem, an electric heater is installed at the lower portion of the evaporator, for directly defrosting the surface of the evaporator.

FIG. 1 is a side-sectional view illustrating a conventional defrost apparatus of a refrigerator, and FIG. 2 is a graph showing a temperature inside the refrigerator in the operation of the conventional defrost apparatus of the refrigerator.

Referring to FIG. 1, in the conventional refrigerator, a freezing chamber F and a refrigerating chamber R are installed at upper and lower portions of a front surface of a refrigerator main body 2a and 2b, a freezing chamber door 4a and a refrigerating chamber door 4b are installed to be opened and closed on the front surface of the refrigerator main body 2a and 2b, an evaporator 10 is installed on the space formed on the inner wall of the freezing chamber F, a freezing cycle including the evaporator 10 is installed at one side of the refrigerator main body 2a and 2b, and a ventilation fan 12 and a motor 14 are installed at the upper portion of the evaporator 10, for sending the cool air to the freezing chamber F and the refrigerating chamber R.

Here, the refrigerator main body 2a and 2b includes an insulation material (not shown) between an outer casing 2a and an inner casing 2b. A compressor 6, a condenser 8 and a capillary tube (not shown) connected to the evaporator 10 through refrigerant tubes are built in a mechanical chamber formed at the lower portion of the refrigerator main body 2a and 2b. The evaporator 10 is built in the inner casing 2b of the freezing chamber F, and a drain tube (not shown) for guiding condensed water formed on the surface of the evaporator 10 and a drain fan (not shown) for collecting the condensed water are installed at the lower portion of the condenser 8.

A cool air circulation path is formed inside the inner casing 2b of the refrigerating chamber R and a plurality of cool air distribution holes 2h are formed in the inner casing 2b of the refrigerating chamber R, so that the cool air heat-exchanged in the evaporator 10 can be circulated in the refrigerating chamber R as well as the freezing chamber F.

A temperature sensor (not shown) and a defrost heater 20 are installed at one side of the evaporator 10. Even if moisture of the air passing through the evaporator 10 is frozen on the surface of the evaporator 10, frost formation is sensed by the temperature sensor and the evaporator 10 is defrosted by the defrost heater 20.

The components such as the compressor 6 and the motor 14 are connected to and controlled by a control unit (not shown).

Accordingly, when the control unit operates the compressor 6 and the motor 14, the refrigerants are circulated through the compressor 6, the condenser 8, the capillary tube and the evaporator 10, and exchange heat with the ambient air of the evaporator 10, thereby generating the cool air. When the ventilation fan 12 is rotated, the cool air is sent to the freezing chamber F and the refrigerating chamber R in order to perform the freezing and refrigerating operations.

On the other hand, when the control unit senses frost formation on the surface of the evaporator 10 by the temperature sensor, the control unit stops the operations of the compressor 6 and the ventilation fan 12, and operates the defrost heater 20 to defrost the evaporator 10. When the surface of the evaporator 10 is defrosted, the control unit resumes the freezing and refrigerating operations.

However, the conventional defrost apparatus of the refrigerator includes the defrost heater 20 adjacently to the evaporator 10 so as to defrost the surface of the evaporator 10. As illustrated in FIG. 2, while the defrost heater 20 is operated, the air heated along the opened cool air circulation path is circulated to cause a heat shock sharply increasing the temperature of the freezing chamber F. It is thus difficult to maintain the food fresh.

To solve the foregoing problem, as disclosed under Japanese Laid-Open Patent Application 9-33157, an evaporator is partitioned off by a center partition plate, and thermostats and heaters corresponding to each area of the evaporator are installed at the upper and lower portions thereof. The heaters are individually operated to partially defrost the evaporator.

However, in the conventional defrost apparatus, when the two heaters are installed in each area of the evaporator, even if the partition is installed to partition the two heaters and each area of the evaporator, the air paths are linked at the top and bottom ends of the evaporator. Accordingly, the air passing through the defrosted portion of the evaporator and the air passing through the non-defrosted portion of the evaporator are mixed and supplied to the freezing chamber F, to increase the temperature of the freezing chamber F.

In addition, in the conventional defrost apparatus, one evaporator formed by installing a plurality of fins on one refrigerant tube is partitioned off by the partition, and the defrost heaters are installed in each area of the evaporator. Even if heat is applied to one side evaporator of the partition, heat is transmitted to the other side evaporator through the refrigerant tube and the plurality of fins, thereby performing the defrosting operation at a time. The heat transmitted to the whole evaporator heats the ambient air and supplies the heated air to the freezing chamber F, thereby increasing the temperature of the freezing chamber F. As a result, the food cannot be maintained fresh for an extended period of time.

DISCLOSURE OF THE INVENTION

The present invention is achieved to solve the above problems. An object of the present invention is to provide a defrost apparatus of a refrigerator which can prevent temperature rise in a whole freezing chamber by locally defrosting two evaporators individually installed on the inner wall of the freezing chamber by heaters corresponding to the evaporators.

Another object of the present invention is to provide a defrost apparatus of a refrigerator which can prevent temperature rise in a freezing chamber by selectively forming air guiding paths, even if two evaporators installed on the inner wall of the freezing chamber are defrosted by heaters corresponding to the evaporators.

In order to achieve the above-described objects of the invention, there is provided a defrost apparatus of a refrigerator, including: a refrigerator main body in which a freezing chamber and a refrigerating chamber are formed, cool air circulation holes being formed on a partition wall for separating the freezing chamber from the refrigerating chamber; a freezing cycle including first and second evaporators installed on a cool air circulation path on the inner wall of the freezing chamber, for cooling the air by the heat exchange operation with refrigerants, and a compressor, a condenser and expansion means built in one side of the refrigerator main body to be connected to the first and second evaporators, for circulating the refrigerants; a ventilation device installed at one side of the first and second evaporators, for sending the cool air from the first and second evaporators to the freezing chamber; temperature sensors installed in the first and second evaporators, for sensing temperature variations of the first and second evaporators, respectively; first and second defrost heaters installed in the first and second evaporators and controlled according to the sensing values of the temperature sensors, for defrosting the first and second evaporators, respectively; a refrigerant distributing means for wholly or selectively distributing the refrigerants to the first and second evaporators; a path varying means installed between the first and second evaporators, for controlling inflow of the cool air to the first and second evaporators; and a control unit for controlling the operations of the ventilation device, the first and second defrost heaters, the refrigerant distributing means and the path varying means according to the sensing values of the temperature sensors.

Preferably, the expansion means are first and second capillary tubes connected to the first and second evaporators, respectively, for decompressing the refrigerants, and the refrigerant distributing means is a 3-way valve installed between the condenser and the first and second capillary tubes.

Preferably, the path varying means includes a partition wall installed on the cool air circulation path, for partitioning off the first and second evaporators, and first and second dampers rotatably installed on the front and rear ends of the partition wall, for selectively controlling inflow of the cool air to the first and second evaporators.

Preferably, the control unit operates one of the first and second defrost heaters or stops the first and second defrost heaters according to the sensing values of the temperature sensors, and continuously operates the ventilation device.

More preferably, when the first defrost heater is operated, the control unit controls the 3-way valve to supply the refrigerants to the second capillary tube and the second evaporator, and also controls the first and second dampers to supply the cool air to the second evaporator. Conversely, when the second defrost heater is operated, the control unit controls the 3-way valve to supply the refrigerants to the first capillary tube and the first evaporator, and also controls the first and second dampers to supply the cool air to the first evaporator.

Preferably, when the first and second defrost heaters are not operated, the control unit controls the 3-way valve to supply the refrigerants to the first and second capillary tubes and the first and second evaporators, and also controls the first and second dampers to supply the cool air to the first and second evaporators.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become better understood with reference to the accompanying drawings which are given only by way of illustration and thus are not limitative of the present invention, wherein;

FIG. 1 is a side-sectional view illustrating a conventional defrost apparatus of a refrigerator;

FIG. 2 is a graph showing a temperature inside the refrigerator in the operation of the conventional defrost apparatus of the refrigerator;

FIG. 3 is a partially-cut front view illustrating a refrigerator main body to which a defrost apparatus is applied in accordance with the present invention;

FIG. 4 is a structure view illustrating a freezing cycle of the refrigerator using the defrost apparatus in accordance with the present invention;

FIG. 5 is a block diagram illustrating control flow of the defrost apparatus of the refrigerator in accordance with the present invention; and

FIGS. 6a and 6b are structure views illustrating refrigerant flow and air flow in the defrosting operation in the freezing cycle of the refrigerator using the defrost apparatus in accordance with the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

A defrost apparatus of a refrigerator in accordance with the present invention will now be described in detail with reference to the accompanying drawings.

Referring to FIGS. 3 and 5, in the refrigerator, a freezing chamber F and a refrigerating chamber R are formed at both sides of a refrigerator main body 52 having its front surface opened, a cool air circulation path A is formed on the inner wall of the freezing chamber F, first and second evaporators 68a and 68b and a ventilation device are installed on the cool air circulation path A of the freezing chamber F, and the freezing cycle except the first and second evaporators 68a and 68b is installed in a space formed at one side of the freezing chamber F and/or the refrigerating chamber R. When the freezing cycle and the ventilation device are driven, the cool air is supplied to the freezing chamber F and the refrigerating chamber R. First and second temperature sensors 69a and 69b and first and second defrost heaters 72a and 72b are installed at the upper and lower portions of the first and second evaporators 68a and 68b in order to rapidly sense and defrost the frost-formed surfaces of the first and second evaporators 68a and 68b. A path varying means is further installed to guide flow of the ambient air of the first and second evaporators 68a and 68b by the operations of the first and second defrost heaters 72a and 72b. A control unit 90 controls the operations of the components including the path varying means.

A partition wall 54 is formed long in the up/down longitudinal direction in the refrigerator main body 52 having its front surface opened. The freezing chamber F and the refrigerating chamber R are formed side by side at both sides of the partition wall 54. The first and second evaporators 68a and 68b are installed side by side on the cool air circulation path A on the inner wall of the freezing chamber F, and cool air discharge holes 52h for discharging the cool air generated around the first and second evaporators 68a and 68b are formed thereon.

Here, an inflow path 54a for supplying the cool air of the freezing chamber F to the refrigerating chamber R and a recovering path 54b for recovering the cool air of the refrigerating chamber R to the cool air circulation path A of the freezing chamber F are formed on the partition wall 54. Preferably, the inflow path 54a and the recovering path 54b are formed at the upper and lower portions of the partition wall 54, respectively, so that the cool air supplied to the refrigerating chamber R through the inflow path 54a can be circulated in the refrigerating chamber R and recovered.

The freezing cycle includes a compressor 62, a condenser 64, expansion means 66a and 66b and the first and second evaporators 68a and 68b connected to each other through refrigerant tubes, so that the refrigerants can be compressed, condensed, evaporated and expanded during the circulation to perform the cooling operation. The expansion means 66a and 66b can be comprised of first and second electronic expansion valves for controlling decompression of refrigerants, but are comprised of generally-used first and second capillary tubes 66a and 66b. The first and second capillary tubes 66a and 66b are connected to the first and second evaporators 68a and 68b, respectively.

The decompression degree of the first and second capillary tubes 66a and 66b is determined in proportion to the capacity of the first and second evaporators 68a and 68b. The diameter and length of the first and second capillary tubes 66a and 66b are determined according to the decompression degree. Here, when the decompression degree of the first and second capillary tubes 66a and 66b increases, the diameter thereof is narrowed and the length thereof is lengthened.

A refrigerant distributing means for wholly or selectively distributing the refrigerants to the first and second evaporators 68a and 68b by controlling the inflow direction of the refrigerants is installed between the condenser 64 and the first and second capillary tubes 66a and 66b. Preferably, a 3-way valve 65 is used as the refrigerant distributing means. The 3-way valve 65 is installed at the branch point of the refrigerant tubes between the condenser 64 and the first and second capillary tubes 66a and 66b.

The ventilation device is fixedly installed on the cool air circulation path A to be positioned over the first and second evaporators 68a and 68b. The ventilation device includes a ventilation fan 70 and a motor to send the cool air. When the ventilation fan 70 is operated, the cool air passing through the first and second evaporators 68a and 68b is forcibly sent and discharged through the cool air discharge holes 52h.

The ventilation device can be comprised of a pair of ventilation fans and motors installed at the upper portions of the first and second evaporators 68a and 68b, respectively.

The first and second temperature sensors 69a and 69b are installed at the upper portions of the first and second evaporators 68a and 68b, for sensing the temperature of the surfaces of the first and second evaporators 68a and 68b, respectively. The temperature and the temperature variations are inputted to the control unit 90. The control unit 90 controls the operations of each component.

Here, the sensing values of the first and second temperature sensors 69a and 69b are inputted to the control unit 90. The control unit 90 decides whether frost has been formed on the first and second evaporators 68a and 68b according to the sensing value variations of the first and second temperature sensors 69a and 69b and the refrigerant supply to the first and second evaporators 68a and 68b. Even if the refrigerants are supplied to the first and second evaporators 68a and 68b, if the sensing values of the first and second temperature sensors 69a and 69b are over a predetermined temperature, the control unit 90 decides that frost has been formed on the first and second evaporators 68a and 68b.

The first and second defrost heaters 72a and 72b are electric heaters installed at the lower portions of the first and second evaporators 68a and 68b for defrosting the surfaces of the first and second evaporators 68a and 68b, respectively. The operations of the first and second defrost heaters 72a and 72b are controlled by the control unit 90 according to the sensing values from the first and second temperature sensors 69a and 69b.

The first and second defrost heaters 72a and 72b are not operated at the same time but selectively operated. Preferably, the capacity of the first and second defrost heaters 72a and 72b is determined in proportion to the capacity of the first and second evaporators 68a and 68b.

The path varying means includes a partition wall 82 for partitioning off the first and second evaporators 68a and 68b side by side on the cool air circulation path A, and first and second dampers 84a and 84b rotatably installed at the front and rear ends of the partition wall 82, for selectively controlling inflow of the cool air to the first and second evaporators 68a and 68b. The operations of the first and second dampers 84a and 84b are also controlled by the control unit 90.

More components can be used to control the operations of the first and second dampers 84a and 84b by the control unit 90, but detailed explanations thereof are omitted.

In the freezing and refrigerating operations, the control unit 90 senses the temperature of the freezing chamber F and the temperature of the refrigerating chamber R, and controls the operations of each component. However, in the defrosting operation, the control unit 90 controls the operations of the first and second defrost heaters 72a and 72b, the first and second dampers 84a and 84b and the 3-way valve 65 according to the temperature values of the first and second temperature sensors 69a and 69b.

In the freezing and refrigerating operations, the control unit 90 wholly opens the 3-way valve 65 and operates the compressor 62 and the ventilation fan 70, so that the refrigerants can pass through the compressor 62, the condenser 64, the first and second capillary tubes 66a and 66b and the first and second evaporators 68a and 68b, and that the cool air generated by the heat exchange operation around the first and second evaporators 68a and 68b can be supplied to the freezing chamber F and the refrigerating chamber R.

Preferably, the first and second dampers 84a and 84b are positioned in the neutral position, so that the air can flow through the first and second evaporators 68a and 68b to maximize the heat exchange area.

On the other hand, in the defrosting operation, the control unit 90 decides whether the first and second evaporators 68a and 68b have been defrosted according to the measured temperature values of the first and second temperature sensors 69a and 69b. In a state where the ventilation fan 70 is continuously operated, the first and second evaporators 68a and 68b are sequentially defrosted one by one, which will now be explained in detail.

The operation of the defrost apparatus of the refrigerator in accordance with the present invention will now be described in detail.

When the control unit 90 senses frost formation on the surface of the first evaporator 68a according to the measured temperature values of the first and second temperature sensors 69a and 69b, as shown in FIG. 6a, the control unit 90 operates the first defrost heater 72a, controls the 3-way valve 65 to supply the refrigerants to the second capillary tube 66b and the second evaporator 68b, controls the first and second dampers 84a and 84b to intercept air flow to the first evaporator 68a and open air flow to the second evaporator 68b, and continuously operates the ventilation fan 70.

Accordingly, when the first defrost heater 72a is operated, the surface of the first evaporator 68a is defrosted. The refrigerants are circulated through the compressor 62, the condenser 64, the second capillary tube 66b and the second evaporator 68b, thereby cooling the ambient air of the second evaporator 68b. When the ventilation fan 70 is operated, the air is supplied merely to the second evaporator 68b, and thus the cool air around the second evaporator 68b is re-supplied to and circulated in the freezing chamber F. Conversely, the warm air around the first evaporator 68a is not directly supplied to the freezing chamber F.

On the other hand, when the control unit 90 senses frost formation on the surface of the second evaporator 68b according to the measured temperature values of the first and second temperature sensors 69a and 69b, as shown in FIG. 6b, the control unit 90 operates the second defrost heater 72b, controls the 3-way valve 65 to supply the refrigerants to the first capillary tube 66a and the first evaporator 68a, controls the first and second dampers 84a and 84b to intercept air flow to the second evaporator 68b and open air flow to the first evaporator 68a, and continuously operates the ventilation fan 70.

Therefore, when the second defrost heater 72b is operated, the surface of the second evaporator 68b is defrosted. The refrigerants are circulated through the compressor 62, the condenser 64, the first capillary tube 66a and the first evaporator 68a, thereby cooling the ambient air of the first evaporator 68a. When the ventilation fan 70 is operated, the air is supplied merely to the first evaporator 68a, and thus the cool air around the first evaporator 68a is re-supplied to and circulated in the freezing chamber F. Conversely, the warm air around the second evaporator 68b is not directly supplied to the freezing chamber F.

When the control unit 90 senses frost formation on the surfaces of the first and second evaporators 68a and 68b at the same time according to the measured temperature values of the first and second temperature sensors 69a and 69b, the control unit 90 sequentially defrosts the first and second evaporators 68a and 68b in the same manner.

Although the preferred embodiments of the present invention have been described, it is understood that the present invention should not be limited to these preferred embodiments but various changes and modifications can be made by one skilled in the art within the spirit and scope of the present invention as hereinafter claimed.

Claims

1. A defrost apparatus of a refrigerator, comprising:

a refrigerator main body in which a freezing chamber and a refrigerating chamber are formed, cool air circulation holes being formed on a partition wall for separating the freezing chamber from the refrigerating chamber;

a freezing cycle including first and second evaporators installed on a cool air circulation path on the inner wall of the freezing chamber, for cooling the air by the heat exchange operation with refrigerants, and a compressor, a condenser and expansion means built in one side of the refrigerator main body to be connected to the first and second evaporators, for circulating the refrigerants;

a ventilation device installed at one side of the first and second evaporators, for sending the cool air from the first and second evaporators to the freezing chamber;

temperature sensors installed in the first and second evaporators, for sensing temperature variations of the first and second evaporators, respectively;

first and second defrost heaters installed in the first and second evaporators and controlled according to the sensing values of the temperature sensors, for defrosting the first and second evaporators, respectively;

a refrigerant distributing means for wholly or selectively distributing the refrigerants to the first and second evaporators;

a path varying means installed between the first and second evaporators, for controlling inflow of the cool air to the first and second evaporators; and

a control unit for controlling the operations of the ventilation device, the first and second defrost heaters, the refrigerant distributing means and the path varying means according to the sensing values of the temperature sensors.

2. The defrost apparatus of claim 1, wherein the expansion means are first and second capillary tubes connected to the first and second evaporators, respectively, for decompressing the refrigerants, and the refrigerant distributing means is a 3-way valve installed between the condenser and the first and second capillary tubes.

3. The defrost apparatus of claim 2, wherein the path varying means comprises a partition wall installed on the cool air circulation path, for partitioning off the first and second evaporators, and first and second dampers rotatably installed on the front and rear ends of the partition wall, for selectively controlling inflow of the cool air to the first and second evaporators.

4. The defrost apparatus of claim 3, wherein the control unit operates one of the first and second defrost heaters or stops the first and second defrost heaters according to the sensing values of the temperature sensors, and continuously operates the ventilation device.

5. The defrost apparatus of claim 4, wherein, when the first defrost heater is operated, the control unit controls the 3-way valve to supply the refrigerants to the second capillary tube and the second evaporator, and also controls the first and second dampers to supply the cool air to the second evaporator.

6. The defrost apparatus of claim 4, wherein, when the second defrost heater is operated, the control unit controls the 3-way valve to supply the refrigerants to the first capillary tube and the first evaporator, and also controls the first and second dampers to supply the cool air to the first evaporator.

7. The defrost apparatus of claim 4, wherein, when the first and second defrost heaters are not operated, the control unit controls the 3-way valve to supply the refrigerants to the first and second capillary tubes and the first and second evaporators, and also controls the first and second dampers to supply the cool air to the first and second evaporators.

8. The defrost apparatus of claim 5, wherein, when the second defrost heater is operated, the control unit controls the 3-way valve to supply the refrigerants to the first capillary tube and the first evaporator, and also controls the first and second dampers to supply the cool air to the first evaporator.

9. The defrost apparatus of claim 5, wherein, when the first and second defrost heaters are not operated, the control unit controls the 3-way valve to supply the refrigerants to the first and second capillary tubes and the first and second evaporators, and also controls the first and second dampers to supply the cool air to the first and second evaporators.

10. The defrost apparatus of claim 6, wherein, when the first and second defrost heaters are not operated, the control unit controls the 3-way valve to supply the refrigerants to the first and second capillary tubes and the first and second evaporators, and also controls the first and second dampers to supply the cool air to the first and second evaporators.