Title of Invention

"DIRECT COLLING TYPE REFREIGERATOR"

Abstract

A direct cooling type refrigerator comprising : a cabinet (30) and an inner case (50) arranged therein to define a refrigerating chamber (R); a thermal insulator (31) interposed between the cabinet (30) and the inner case (50) ; an evaporator (70) arranged between the inner case (50) and the thermal insulator (31) and adapted to cool the inner case (50) ; a temperature sensor (80) installed at the evaporator (70) for sensing the temperature of the evaporator (70) ; and a control unit (C) for controlling a compressor (54), based on the temperature sensed by the temperature sensor (80), is characterized in that a heat transfer promoting means (90) is attached to the evaporator (70) at a region where the temperature sensor (80) is installed, for rapidly transmitting a temperature of the thermal insulator (31) to the temperature sensor (80).

Full Text

BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a direct cooling type refrigerator, and more particularly to a direct cooling type refrigerator capable of accurately and rapidly sensing a variation in the temperature of a thermal insulator provided in the refrigerator by a temperature sensor installed in an evaporator in order to control a compressor based on the sensed result. Description of Related Art In accordance with cooling type, refrigerators may be classified into a direct cooling type, in which an inner case defined with a freezing chamber and a refrigerating chamber is directly cooled by an evaporator in order to cool the freezing and refrigerating chambers, and an indirect cooling type, in which cold air generated in accordance with a heat exchanging operation conducted by the evaporator is supplied into the interiors of the freezing and refrigerating chambers by a cooling fan. A conventional direct cooling type refrigerator, includes a freezing chamber, a refrigerating chamber arranged beneath the freezing chamber, a compressor for compressing a refrigerant, and a condenser for condensing a high-pressure refrigerant gas emerging from the compressor. The refrigerator also includes a capillary tube for reducing the pressure of the refrigerant emerging from the condenser, a freezing 2 chamber evaporator for exchanging heat with an inner case defining the freezing chamber, thereby cooling the freezing chamber, a refrigerating chamber evaporator for exchanging heat with an inner case defining the refrigerating chamber, thereby cooling the refrigerating chamber, a temperature sensor for measuring the temperature of the refrigerating chamber evaporator, and a control unit for turning on the compressor when the temperature sensed by the temperature sensor is equal to or higher than a predetermined temperature, for example 5°C, while turning off the compressor when the sensed temperature is equal to or lower than a predetermined temperature, for example -30°C. Each of the freezing and refrigerating chamber evaporators is provided with inner and outer plate members joined to each other. In order to form refrigerant passages, convex portions are provided at the outer plate member. The inner and outer plate members are interposed between the inner case of the associated freezing or refrigerating chamber and a thermal insulator. The refrigerant passages are formed to allow the refrigerant to pass through the freezing chamber evaporator, the refrigerant chamber evaporator, and then again through the freezing chamber evaporator. A space which is adapted to receive the temperature sensor, is defined between the inner and outer plate members at a region where the lower portions of the inner and outer plate members are disposed. In the illustrated 3 case, the space is formed by outwardly protruding an associated portion of the outer plate member to form a convex structure. The temperature sensor includes a closed tube received in the space, a gas contained in the tube and adapted to increase/decrease in pressure in accordance with a variation in the temperature of the tube, and a thermistor adapted to output, to the control unit, a temperature signal corresponding to the increased/decreased pressure of the gas. The temperature of the thermal insulator of the conventional refrigerator is increased in temperature under the influence of ambient heat in a state in which the compressor is in its OFF state. However, such a variation in the temperature of the thermal insulator is not rapidly transmitted to the temperature sensor because the outer plate member of the refrigerating chamber evaporator is interposed between the thermal insulator and the space where the temperature sensor is disposed. For this reason, it is impossible to accurately control the compressor based on a variation in the temperature of the thermal insulator. The compressor is controlled to be turned on when the temperature sensed by the temperature sensor corresponds to 5°C, while being turned off when the sensed temperature corresponding to -30°C. Under the influence of the temperature of the thermal insulator, the temperature of the refrigerating chamber 4 evaporator where the temperature sensor is installed may be increased at an accelerated rate because the temperature of the thermal insulator is typically higher than the temperature of the evaporator. In this case, therefore, points of time at which the compressor is switched to its ON state, are earlier than points of time at which the compressor is switched to its ON state in the case where the temperature of the thermal insulator has no influence. On the other hand, points of time at which the compressor is switched to its OFF state in the case where the temperature of the thermal insulator has an influence, is later than points of time at which the compressor is switched to its ON state in the case where the temperature of the thermal insulator has no influence. Accordingly, it is impossible to accurately control the compressor in response to a variation in the temperature of the refrigerating chamber unless the variation in the temperature of the thermal insulator is rapidly transmitted to the temperature sensor. Furthermore, the ON time of the compressor in the case where the temperature of the thermal insulator has no influence is shorter than the ON time of the compressor in the case where the temperature of the thermal insulator has an influence ; whereas the OFF time of the compressor in the case where the temperature of the thermal insulator has no influence is longer than the OFF time of the compressor in the case where the temperature of the thermal insulator has an influence. For this reason, there is a problem in that the temperature deviation between the freezing and refrigerating chambers is larger than an allowable value. 5 SUMMARY OF THE INVENTION Therefore, the present invention has been made to overcome the above mentioned problems involved with the related art, and an object of the invention is to provide a direct cooling type refrigerator capable of allowing the temperature of a refrigerating chamber evaporator at a region where a temperature sensor is installed to be rapidly varied depending on a variation in the temperature of a thermal insulator disposed around the temperature sensor, thereby achieving an accurate refrigerator temperature control. Another object of the invention is to provide a direct cooling type refrigerator capable of reducing the OFF time of a compressor, thereby preventing temperature deviation between freezing and refrigerating chambers from increasing above an allowable value. To achieve these objects, the present invention provides a direct cooling type refrigerator comprising : a cabinet for constituting an outer structure of the refrigerator; an inner case arranged in the cabinet and adapted to define a refrigerating chamber; a thermal insulator interposed between the cabinet and the inner case ; an evaporator arranged between the inner case and the thermal insulator and adapted to cool the inner case ; a temperature sensor installed at the evaporator and adapted to sense the 6 temperature of the evaporator; a control unit for controlling a compressor, based on the temperature sensed by the temperature sensor; characterized in that a heat transfer promoting means is attached to the evaporator at a region where the temperature sensor is installed, for rapidly transmitting a temperature of the thermal insulator to the temperature sensor. BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS The above objects, and other features and advantages of the present invention will become more apparent after a reading of the following detailed description when taken in conjunction with the accompanying drawings in which : Fig. 1 is a sectional view illustrating a conventional direct cooling type refrigerator; Fig. 2 is a circuit diagram illustrating a general refrigerant cycle used in direct cooling type refrigerators; Fig. 3 is a sectional view illustrating an evaporator used in direct cooling type refrigerators; Fig. 4 is a graph depicting ON/OFF intervals of a compressor in direct cooling type refrigerator; Fig. 5 is a sectional view illustrating a direct cooling type refrigerator according to a first embodiment of the present invention ; Fig. 6 is an enlarged view illustrating a portion "A" in Fig. 5 ; and 7 Fig. 7 is a sectional view illustrating an essential portion of a direct cooling type refrigerator according to a second embodiment of the present invention. DESCRIPTION OF PRIOR ART Referring to Figs. 1 and 2, a conventional direct cooling type refrigerator is illustrated. As shown in Figs. 1 and 2, the refrigerator includes a freezing chamber F, a refrigerating chamber R arranged beneath the freezing chamber F, a compressor 4 for compressing a refrigerant, and a condenser 6 for condensing a high-pressure refrigerant gas emerging from the compressor 4. The refrigerator also includes a capillary tube (not shown) for reducing the pressure of the refrigerant emerging from the condenser 6, a freezing chamber evaporator 10 for exchanging heat with an inner case 11 defining the freezing chamber F, thereby cooling the freezing chamber F, a refrigerating chamber evaporator 20 for exchanging heat with an inner case 21 defining the refrigerating chamber R, thereby cooling the refrigerating chamber R, a temperature sensor 26 for measuring the temperature of the refrigerating chamber evaporator 20, and a control unit 30 for turning on the compressor 4 when the temperature sensed by the temperature sensor 26 is equal to or higher than a predetermined temperature, for example, 5°C, while turning off the compressor 4 when the sensed temperature is equal to or lower than a predetermined temperature, for example, -30°C. As shown in Figs. 1 and 3, each of the freezing and refrigerating chamber evaporators 10 and 20 includes inner and outer plate members 15 and 16 joined to each 8 other. In order to form refrigerant passages 12 and 22, convex portions 17 and 18 are provided at the outer plate member 16. The inner and outer plate members 15 and 16 are interposed between the inner case 11 or 21 of the associated freezing or refrigerating chamber F or R and a thermal insulator 13. The refrigerant passages 12 and 22 are formed to allow the refrigerant to pass through the freezing chamber evaporator 10, the refrigerant chamber evaporator 20, and then again through the freezing chamber evaporator 10. A space 19, which is adapted to receive the temperature sensor 26, is defined between the inner and outer plate members 15 and 16 at a region where the lower portions of the inner and outer plate members 15 and 16 are disposed. In the illustrated case, the space 19 is formed by outwardly protruding an associated portion of the outer plate member 16 to form a convex structure. The temperature sensor 26 includes a closed tube 27 received in the space 19, a gas 28 contained in the tube 27 and adapted to increase/decrease in pressure in accordance with a variation in the temperature of the tube 27, and a thermistor (not shown) adapted to output, to the control unit 30, a temperature signal corresponding to the increased/decreased pressure of the gas 28. 9 Now, the operation of the conventional direct cooling type refrigerator having the above described configuration will be described. After the refrigerant is changed into a vapor phase of high temperature and high pressure as it is compressed by the compressor 4, it is introduced into the condenser 6. In the condenser 6, the refrigerant discharges its heat, so that it is changed into a liquid phase of normal temperature and high pressure. That is, the refrigerant is condensed by the condenser 6. The condensed refrigerant is then reduced in pressure as it passes through the capillary tube 8. Subsequently, the refrigerant exchanges heat with the inner cases 11 and 21 of the freezing and refrigerating chambers F and R while passing though the refrigerant passage 12 of the freezing chamber evaporator 10 and the refrigerant passage 22 of the refrigerating chamber evaporator 20. Thus, the freezing and refrigerating chambers F and R are cooled. Meanwhile, the temperature sensor 26 installed at the refrigerating chamber evaporator 20 senses the temperature of the refrigerating chamber evaporator 20 at the lower portion of the refrigerating chamber evaporator 20, and sends a sensing signal indicative of the sensed temperature. When the control unit 30 determines, based on the sensing signal, that the temperature of the refrigerating chamber evaporator 20 is equal to or lower than a predetermined value, it outputs an OFF signal to the compressor 4 so as to stop the operation of the compressor 4. On the other hand, when the control unit 30 determines that the temperature of the refrigerating chamber evaporator 20 10 is equal to or higher than the predetermined value, it outputs an ON signal to the compressor 4 so as to operate the compressor 4. The temperature of the thermal insulator 13 of the conventional refrigerator is increased under the influence of ambient heat in a state in which the compressor 4 is in its OFF state. However, such a variation in the temperature of the thermal insulator 13 is not rapidly transmitted to the temperature sensor 28 because the outer plate member 18 of the refrigerating chamber evaporator 20 is interposed between the thermal insulator 12 and the space 19 where the temperature sensor 26 is disposed. For this reason, it is impossible to accurately control the compressor 4 based on a variation in the temperature of the thermal insulator 12. This will be described in more detail with reference to Fig 4, In Fig. 4, the solid line A represents a variation in the temperature sensed by the temperature sensor 28 when it is assumed that the variation in the temperature of the thermal insulator 13 has no influence on the refrigerating chamber evaporator 20, whereas the phantom line B represents a variation in the temperature sensed by the temperature sensor 26 when it is assumed that the variation in the temperature of the thermal insulator 12 has influence on the refrigerating chamber evaporator 20. Referring to Fig. 4, the compressor 4 is controlled to be turned on when the temperature sensed by the temperature sensor 28 corresponds to 5ºC, while being turn off when the sensed temperature corresponding to -30°G. Under the influence of the temperature of the thermal insulator 13, the 11 temperature of the refrigerating chamber evaporator where the temperature sensor 26 is installed may be increased at an accelerated rate because the temperature of the thermal insulator 13 is typically higher than the temperature of the evaporator 20. In this case, therefore, points of time, T11, T13, and T15, at which the compressor 4 is switched to its ON state, are earlier than points of time, T1, T3, and T5, at which the compressor 4 is switched to its ON state in the case where the temperature of the thermal insulator 13 has no influence. On the other hand, points of time, T12 and T14 at which the compressor is switched to its OFF state in the case where the temperature of the thermal insulator 13 has an influence, is later than points of time, T2 and T4, at which the compressor 4 is switched to its ON state in the case where the temperature of the thermal insulator 13 has no influence. Accordingly, it is impossible to accurately control the compressor 4 in response to a variation in the temperature of the refrigerating chamber R unless the variation in the temperature of the thermal insulator 13 is rapidly transmitted to the temperature sensor 26. Furthermore, the ON time of the compressor 4 in the case where the temperature of the thermal insulator 13 has no influence is shorter than the ON time 11 of the compressor 4 in the case where the temperature of the thermal insulator 13 has an influence ; whereas the OFF time 2 of the compressor 4 in the case where the temperature of the thermal insulator 13 has no influence is longer than the OFF time 12 of the compressor 4 in the case where the temperature of the thermal insulator 13 has an influence. For this reason, there is a problem in that the temperature deviation between the freezing and refrigerating chambers F and R is larger than an allowable value. 12 DESCRIPTION OF THE PREFERRED EMBODIMENTS Now, embodiments of the present invention will be described in conjunction with the accompanying drawings. Fig. 5 is a sectional view illustrating a direct cooling type refrigerator according to an embodiment of the present invention. As shown in Fig. 5, the direct cooling type refrigerator includes a cabinet 30 for constituting the outer structure of the refrigerator, inner cases 40 and 50 for defining freezing 13 and refrigerating chambers F and R, and a thermal insulator 31 interposed between the cabinet 30 and the inner cases 40 and 50. The refrigerator also includes a compressor 54 for compressing a refrigerant, a condenser 56 for condensing a refrigerant gas emerging from the compressor 54, a capillary-tube {not shown) for reducing the pressure of the refrigerant emerging from the condenser 6, a freezing chamber evaporator 60 for exchanging heat with the inner case 40 defining the freezing chamber F, thereby cooling the freezing chamber F, and a refrigerating chamber evaporator 70 for exchanging heat with the inner case 50 defining the refrigerating chamber R, thereby cooling the refrigerating chamber R. The refrigerator further includes heat transfer promoting means 90 for promoting transfer of heat from the thermal insulator 31 to the refrigerating chamber evaporator 70, and a control unit C for turning on/off the compressor 54 based on a temperature value sensed by a temperature sensor 80. Each of the freezing and refrigerating chamber evaporators 60 and 70 includes inner and outer plate members 71 and 72 joined to each other while defining refrigerant passages 63 and 73 therebetween. The inner and outer plate members 71 and 72 are interposed between the inner case 40 or 50 of the associated freezing or refrigerating chamber F or R and the thermal insulator 31. As shown in Fig. 6, the outer plate member 72 has a 14 convex portion 72a protruded toward the thermal insulator 31 at a lower portion of the refrigerating chamber evaporator 70 in order to form a space 75 between the inner and outer plate members 71 and 72. The temperature sensor 80 is disposed in the space 75. The temperature sensor 80 includes a closed tube 81 received in the space 75, a gas 82 contained in the tube 81 and adapted to increase/decrease in pressure in accordance with a variation in the temperature of the tube 81, and a thermistor {not shown) adapted to output, to the control unit C, a temperature signal corresponding to the increased/decreased pressure of the gas 82. The heat transfer promoting means 90 comprises a heat transfer plate 91 having a heat diffusion coefficient higher than that of the outer plate member 72 in order to promote the transfer of heat from the thermal insulator 31 to the convex portion 72a of the outer plate member 72. The heat transfer plate 91 is attached to the outer surface of the convex portion 72 of the outer plate member 72 in the refrigerating chamber evaporator 70. The heat transfer plate 91 has a semicircular shape in order to completely surround the convex portion 72a. The operation of the refrigerator having the above described configuration will be described in conjunction with Figs. 5 and 6. 15 Since the heat transfer plate 90 is arranged around the outer surface of the convex portion 72a of the outer plate member 72 defining the space 75 where the temperature sensor 80 adapted to sense the temperature of the refrigerating chamber evaporator 70 is installed, the temperature of the thermal insulator 31 increased under the influence of ambient temperature in an OFF state of the compressor 54 is rapidly transmitted to the inner and outer plate members 71 and 72 of the refrigerating chamber evaporator at the region where the temperature sensor 80 is disposed. Accordingly, the temperature of the thermal insulator 31 is rapidly transmitted to the temperature sensor 80. Thus, the refrigerator has an improved cooling efficiency because the compressor 54 is controlled based on the temperature of the thermal insulator 31 rapidly transmitted to the temperature sensor 80. In addition, the OFF time of the compressor 54 is reduced as compared to that of the conventional refrigerator. Accordingly, it is possible to prevent the temperature deviation between the freezing and refrigerating chambers from increasing above an allowable value. Referring to Fig. 7, heat transfer promoting means 90 according to a second embodiment of the present invention is illustrated. As shown in Fig. 7, the heat transfer promoting means 90 comprises a hollow enclosed member 92 attached to the outer 16 surface of the convex portion 72a of the outer plate member 72 in the refrigerating chamber evaporator 70 at a region where the temperature sensor 80 is installed. The enclosed member 92 is filled with a gas 93 adapted to promote transfer of heat from the thermal insulator 31, such as air. The enclosed member 92 has a rectangular cross section having, at one surface thereof, a concave surface conforming the convex portion 72a. As apparent from the above description, the present invention provides a direct cooling type refrigerator in which heat transfer promoting means having a high heat diffusion coefficient is installed at a portion of an evaporator where a temperature sensor adapted to sense the temperature of the evaporator, in order to rapidly transfer a variation in the temperature of a thermal insulator filled in the refrigerator. Accordingly, the temperature sensor can rapidly sense an increase in the temperature of the thermal insulator occurring in the OFF state of a compressor, thereby allowing the compressor to be accurately and rapidly controlled. Thus, it is possible to achieve an improvement in the cooling efficiency of the refrigerator. Although the preferred embodiments of the invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope 17 18 and spirit of the invention as disclosed in the accompanying claims. WE CLAIM : 1. A direct cooling type refrigerator comprising : a cabinet (30) for constituting an outer structure of the refrigerator; an inner case (50) arranged in the cabinet (30) and adapted to define a refrigerating chamber(R); a thermal insulator (31) interposed between the cabinet (30) and the inner case(50); an evaporator (70) arranged between the inner case (50) and the thermal insulator (31) and adapted to cool the inner case (50); a temperature sensor (80) installed at the evaporator (70) and adapted to sense the temperature of the evaporator (70); and a control unit (C) for controlling a compressor (54) , based on the temperature sensed by the temperature sensor (80), characterized in that a heat transfer promoting means (90) is attached to the evaporator (70) at a region where the temperature sensor (80) is installed, for rapidly transmitting a temperature of the thermal insulator (31) to the temperature sensor (80). 2. The direct cooling type refrigerator as claimed in claim 1, wherein the evaporator (70) comprises inner and outer plate members (71, 72) joined to each other, and the heat transfer promoting means (90) is attached to the outer plate member (72) of the evaporator (70). 19 3. The direct cooling type refrigerator as claimed in claim 1, wherein the heat transfer promoting means (90) is arranged between the evaporator (70) and the thermal insulator (31). 4. The direct cooling type refrigerator as claimed in claim 1, wherein the heat transfer promoting means (90) comprises a heat transfer plate (91). 5. The direct cooling type refrigerator as claimed in claim 4, wherein the evaporator (70) has a convex portion (72a) providing a space for installing the temperature sensor(80), and the heat transfer plate (91) has a semicircular shape so that it completely surrounds the convex portion (72a) of the outer plate member (72). 6. The direct cooling type refrigerator as claimed in claim 4, wherein the heat transfer plate (91) is made of a metal having a thermal diffusivity higher than that of the evaporator (70). 7. The direct cooling type refrigerator as claimed in claim 1, wherein the heat transfer promoting means (90) comprises a hollow enclosed member (92) filled with a heat transfer promoting gas. 20 8. The direct cooling type refrigerator as claimed in claim 7, wherein the enclosed member (92) is interposed between the evaporator (70) and the thermal insulator (31). 9. The direct cooling type refrigerator as claimed in claim 7, wherein the enclosed member (92) has at one surface thereof a concave surface adapted to completely surround a convex portion (72a) of the evaporator (70) formed to provide a space for installing the temperature sensor (80). 10. The direct cooling type refrigerator as claimed in claim 7, wherein the gas filled in the enclosed member (92) is air. 11. A direct cooling type refrigerator, substantially as herein described, particularly with reference to and as illustrated in the accompanying drawings. 21 A direct cooling type refrigerator comprising : a cabinet (30) and an inner case (50) arranged therein to define a refrigerating chamber (R); a thermal insulator (31) interposed between the cabinet (30) and the inner case (50) ; an evaporator (70) arranged between the inner case (50) and the thermal insulator (31) and adapted to cool the inner case (50) ; a temperature sensor (80) installed at the evaporator (70) for sensing the temperature of the evaporator (70) ; and a control unit (C) for controlling a compressor (54), based on the temperature sensed by the temperature sensor (80), is characterized in that a heat transfer promoting means (90) is attached to the evaporator (70) at a region where the temperature sensor (80) is installed, for rapidly transmitting a temperature of the thermal insulator (31) to the temperature sensor (80).

Documents:

00354-cal-2002-abstract.pdf

00354-cal-2002-claims.pdf

00354-cal-2002-correspondence.pdf

00354-cal-2002-description(complete).pdf

00354-cal-2002-drawings.pdf

00354-cal-2002-form-1.pdf

00354-cal-2002-form-18.pdf

00354-cal-2002-form-2.pdf

00354-cal-2002-form-3.pdf

00354-cal-2002-form-5.pdf

00354-cal-2002-g.p.a.pdf

00354-cal-2002-letters patent.pdf

00354-cal-2002-priority document others.pdf

00354-cal-2002-priority document.pdf

354-CAL-2002-FORM-27.pdf