| Title of Invention | "REFRIGERATOR" |
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| Abstract | A refrigerator including a cooler; an accumulator accumulating cooling time for cooling the interior of the refrigerator; a defrost controller that periodically defrosts the cooler whenever the accumulated cooling time reaches a defrost time; a temperature detector detecting temperature of the cooler; a specifier that specifies the defrost time of an initial defrost cycle after power supply at an initial defrost time determined based on the temperature of the cooler at the time of power supply; wherein, the specifier specifies the initial defrost time when the temperature of the cooler detected by the temperature detector upon power supply is lower than a predetermined temperature to be less than the initial defrost time when the temperature of the cooler detected by the temperature detector upon power supply is higher than the predetermined temperature. |
| Full Text | REFRIGERATOR FIELD The present disclosure relates to a refrigerator that defrosts its cooler based on the cumulative cool time of its interior. BACKGROUND A refrigerator operates under the control of a controller primarily configured by a microcomputer. Defrosting executed by the cooler for cooling the interior of the refrigerator is also controlled by such controller. To elaborate, the controller accumulates time expended in cooling the refrigerator by the cooler, and defrosts the cooler when the accumulated time reaches the pre-specified defrost time. Under such defrost control, the controller initializes the cumulative cool time when cumulative cool time reaches the specif ied defrost time, in other words, after defrost. Thus, the cooler is defrosted periodically whenever the cumulative cool time reaches the specified defrost time. When power supply to the above configured refrigerator is interrupted by power failures, etc., power supply to the controller is interrupted as well and thus, the controller will lose the cool time accumulated up to the point of interruption. As a result, when power is restored, the controller restarts accumulation of time spent on cooling the refrigerator interior by the cooler from the initialized state even in the absence of defrost execution. In such case, the period in which the cooler is defrosted, in other words, the defrost period is substantially extended to cause the cooler to be prone to excessive defrosting and consequently lead to cooling errors. To address such problems originating from power failure, the refrigerator disclosed, for example, in JP HOl-137184 A is provided with a temperature sensor for sensing the temperature of the cooler and an A/D transformation circuit for transforming the signals outputted from the temperatures sensor into digital signals and outputting the digital signals to the controller. The refrigerator determines the amount of frost formation at the cooler based on the rate of variation in the temperature sensed by the temperature sensor after power has been supplied, in other words, after power has been restored. Based upon the determined amount of frost formation, the refrigerator, after power has been restored, modifies the specified defrost time for the first defrost period. According to the refrigerator disclosed in JP HOl-137184 A. the initial cooler defrosting after power supply or power restoration can be executed based on the amount of frost formation at the cooler which is determined when power is supplied. Thus, cooling errors originating from excessive cooler defrosting can be prevented. However, in case the amount of frost formation at the cooler is determined based on the rate of variation of the cooler temperature, time of some extent is required to obtain the variation rate, and thus, delaying the determination in the amount of frost formation. Further, since circuitry such as a high precision temperature sensor and A/D transformer is required in determining the amount of frost formation, the overall configuration becomes costly. SUMMARY One advantage of the present invention is providing a refrigerator that allows optimized initial defrosting of the refrigerator cooler after power is supplied in a less time consuming, simple, and low cost configuration. In one aspect of the present disclosure, there is provided a refrigerator including A refrigerator, including a cooler that cools an interior of the refrigerator; an accumulator that accumulates cooling time for cooling the interior of the refrigerator by the cooler; a defrost controller that periodically defrosts the cooler whenever the accumulated cooling time accumulated by the accumulator reaches a defrost time; a temperature detector that detects temperature of the cooler; a specifier that specifies the defrost time for an initial defrost cycle after power supply at an initial defrost time determined based on the temperature of the cooler detected by the temperature detector upon power supply; wherein, the specifier specifies the initial defrost time when the temperature of the cooler detected by the temperature detector upon power supply is lower than a predetermined temperature to be less than the initial defrost time when the temperature of the cooler detected by the temperature detector upon power supply is higher than the predetermined temperature. According to the above described configuration, the specifer specifies the defrost time for the initial defrost period, in other words, the initial defrost time after power supply or restoration of power supply depending upon the temperature of the cooler detected at the time of power supply. In such case, the specifier specifies the initial defrost time when the temperature of the cooler upon power supply is less than the predetermined temperature, in other words, when the estimated amount of frost formation at the cooler is substantial, to be less than the initial defrost time when the cooler temperature upon power supply is greater than the predetermined temperature, in other words, when the estimated amount of frost formation at the cooler is insubstantial. Thus, the initial defrost cycle of the cooler after power supply or power restoration can be optimized depending upon the amount of frost formation at cooler estimated upon power supply, thereby preventing cooling errors originating from excessive frost formation at cooler. Further, the refrigerator configured as described above specifies the initial defrost time depending on the temperature as it is detected at cooler. Thus, calculation process for obtaining the variation rate of the cooler temperature can be eliminated. Such configuration will allow circuitry for determining the amount of frost formation at cooler to be eliminated, thereby providing a simple configuration which is less time and cost consuming. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a flowchart indicating a control flow of a defrost control executed by a controller according to a first exemplary embodiment of the present invention; FIG.2 is a vertical cross sectional side view providing an overall view of a refrigerator; FIG.3 is a block diagram schematically indicating an electrical configuration of the refrigerator; FIG. 4 corresponds to FIG. 2 and describes a second exemplary embodiment of the present invention; and FIG.5 is a front view of the refrigerator. DETAILED DESCRIPTION One exemplary embodiment of the present invention will be described with reference to FIGS.l to 3. FIG.2 is a vertical cross sectional side view providing an overall view of refrigerator 1. Refrigerator 1 is provided with an exterior housing 3 made of copper plate, and an inner housing 4 made of plastic. By filling heat insulative material 5 such as hard urethane foam or vacuum heat insulative material between exterior housing 3 and inner housing 4, heat insulation is provided between the refrigerator interior and the refrigerator exterior. Such heat insulative configuration is collectively referred to as heat insulative cabinet 2. The interior of heat resistive cabinet 2, or the refrigerator interior, is delimited into compartments by heat resistive partition 2a, in which the lower compartment constitutes chiller 6 and the upper compartment constitutes freezer 7 . The front faces of chiller 6 and freezer 7 are enclosed by hinged doors 8 and 9, respectively that are configured openable and closable. At the upper portion of the rear wall of chiller 6, chiller temperature sensor 10 for sensing the temperature inside chiller 6 is provided along with damper 11. Temperature sensor 10 is configured such that gas pressure exerted on its tip varies depending upon peripheral temperature and the temperature inside chiller 6 is sensed based on the variation in gas pressure. Damper 11 is provided at the lower end of duct 12. Duct 12 provides communication between the rear wall upper portion of chiller 6 with cooling chamber 13. Damper 11, being driven by the variation in gas pressure of temperature sensor 10, is configured to open and close the opening defined at the lower end of duct 12 by j utilizing the gas pressure that varies depending on the temperature inside chiller 6. On the rear wall of freezer 7, cooling chamber 13 is \ provided. Provided inside cooling chamber 13 are freezer \ temperature sensor 14 for sensing the temperature within freezer j 1, cooler 15 for cooling the interior of chiller 6 and freezer \ 7, and a cooling fan 16. At the proximity of the lower portion j I of cooler 15, defrost heater 17 is provided for melting the frost \ formed on cooler 15. Cooler 15 is further provided with cooler j temperature sensor 18 for sensing the temperature of cooler 15. When cooling fan 16 is driven, cool air generated by cooler j I 15 is circulated into freezer 7 and chiller 6. The cool air I I I generated by cooler 15 flows from cooling chamber 13 into freezer I } 7 and thereafter circulated back into the lower portion of cooling | ii chamber 13 through circulation duct 19. Circulation duct 19 I I provides communication between the bottom of freezer 7 and | I cooling chamber 13. I I Further, after the cool air generated by cooler 15 is I ! It IS i I I I 'k supplied into chiller 6 through duct 12, it is circulated back into the lower portion of cooling chamber 13 from the upper portion of chiller 6 through circulation duct 19. Chiller 6 and freezer 7 are thus, cooled to the preset refrigerating temperature and freezing temperature, respectively. The amount of cool air supplied into chiller 6 is controlled through the amount of opening and closing of duct 12 by damper 11. Though not shown, a freezing cycle configured by cooler 15, compressor 20, a condenser, an accumulator, and a capillary tube interconnected in closed loop by a refrigerant pipe is provided inside refrigerator 1. The freezing cycle is configured such that refrigerant is passed through the condenser by the actuation of compressor 20 to be thereafter supplied to cooler 15 through the capillary tube and circulated back to compressor 20. At the rear side lower portion of refrigerator 1, a machine chamber 21 is provided. Inside machine chamber 21, the aforementioned compressor 20, the condenser, and a cooling fan not shown for cooling compressor 20 and the condenser are provided. Machine chamber 21 is further provided with controller 22 at its upper inner portion. Controller 22 is configured primarily by a microcomputer implemented on control circuit board not shown and controls the overall operation of refrigerator 1. To elaborate, controller 22, as shown in FIG.3, establishes connections with components such as aforementioned temperature sensors 10, 14, and 18, timer 23, an interior light not shown, and a door switch not shown. The door switch detects the opening and closing of doors 8 and 9. Timer 23 accumulates the time expended on cooling the interior of refrigerator 1 by cooler 15, in other words, the interior of chiller 6 and freezer 7. Controller 22 controls components such as cooling fan 16, defrost heater 17, and compressor 20 based on various signals inputted by the above described sensors and switches, and according to a pre-stored operation control program. Further, controller 22 is configured to perform periodic defrosting of cooler 15 through energization of defrost heater 17 whenever cumulative cool time at timer 23 reaches the specified defrost ! time. j Next, a description will be given on the operation of the present exemplary embodiment with reference to FIG.l. FIG.l is i a flowchart of the control flow of the defrost control executed j by controller 22. j When power is supplied to refrigerator 1, controller senses the temperature of cooler 15 at the time of power supply through j 1 temperature sensor 18. Then, controller 22 determines whether i I I or not cooler 15 temperature sensed by temperature sensor 18 is j equal to or less than preset temperature T set at 10 degrees i Celsius in the present exemplary embodiment (step SI). If the I sensed cooler 15 temperature is equal to or less.than preset i j temperature T (step SI: YES) , controller 22 determines that frost I i is formed at cooler 15 or that the amount of frost formation is j excessive and proceeds to step S2 in which initial defrost time j j Jl is specified at 2 . 5 hours for example. If the sensed cooler j I 15 temperature is higher than preset temperature T (step SI: NO) , I I controller 22 determines that not frost is formed at cooler 15 j I ! I I t I or that the amount of frost formation is insubstantial and proceeds to step S3 in which initial defrost time J2 is specified at 5 hours for example. Then, controller 22 proceeds to step 4 and determines whether or not the cumulative cool time Ts accumulated at timer 23 has reached the specified initial defrost time Jl or J2. Controller 22, when determining that cumulative cool time Ts has reached the initial defrost time Jl or J2 (step S4: YES), energizes defrost heater 17 and executes the initial defrost (step S5). Controller 22, when completing the initial defrost, initializes cumulative cool time Ts. Then, controller 22 proceeds to step 86 and determines whether or not cumulative cool time Ts has reached specified normal defrost time J3 in which cooler 15 is defrosted in steady state. Controller 22, when determining that cumulative cool time Ts has reached the specified normal defrost time J3 (step 36: YES), energizes defrost heater 17 and defrosts cooler 15 (step S7: YES). Controller 22, when completing defrosting of cooler 15, initializes cumulative cool time Ts. Then, controller 22 again proceeds to step S6 and determines whether or not cumulative cool time Ts has reached normal defrost time J3 for normal defrosting. Controller 22, when determining that cumulative cool time Ts has reached normal defrost time J3 (step S6: YES), defrosts cooler 15 (step S7: YES). Thus, controller 22 makes a transition to a steady state in which defrost of cooler 15 is periodically executed whenever cumulative cool time Ts reaches specified normal defrost time J3. If power supply to refrigerator is not interrupted by accidents such as power failure, controller 22 continues execution of the above described periodic defrost control. However when refrigerator, when used under poor power supply environment, may encounter power failure during the execution of the above described defrost control. For instance, when power supply to refrigerator 1 is interrupted (step S8: YES) before cumulative cool time Ts reaches initial defrost time Jl or J2 (step S4 : NO) , controller 22 returns the process flow to step SI upon restoration of power supply. When power supply to refrigerator 1 is interrupted (step S9: YES) before cumulative cool time Ts reaches normal defrost time J3 (step S6: NO), controller 22 returns the process flow to step SI upon restoration of power supply. As described above, controller 22, when encountering interruption of power supply to refrigerator 1 during the execution of defrost control, returns the process flow to step SI upon restoration of power supply and specifies initial defrost time Jl or J2 depending upon the cooler 15 temperature sensed when power is restored. Controller 22 specifies the initial defrost time such that relatively shorter defrost time is specified when the temperature sensed at cooler 15 upon power restoration is less than predetermined temperature T, in other words, when amount of frost formation at cooler 15 is substantial, as compared to when the temperature sensed at cooler 15 upon power restoration is greater than predetermined temperature T, in other words, when amount of frost formation at cooler 15 is insubstantial. Thus, the initial defrost cycle of cooler 15 after power supply or power restoration can be optimized depending upon the amount of frost formation at cooler 15 estimated at the time of power supply, and thereby preventing cooling errors due to excessive frost formation at cooler 15. If it is estimated that excessive frost is formed at cooler 15, the initial defrost of cooler 15 is executed in a relatively shorter time span or earlier after power supply. Thus, excessive frost formation at cooler 15 can be prevented with the utmost priority. If it is estimated, on the other hand, that the amount frost formation at cooler 15 is insubstantial, sufficient time span can be secured until execution of the initial defrost of cooler 15 after power supply, thereby allowing sufficient cooling after power supply. Further, controller 22 specifies the initial defrost time depending on the sensed temperature at cooler 15 as it is and not depending on the variation rate calculated by the sensed temperature at cooler 15. Thus, calculation process for obtaining the variation rate of temperature at cooler 15 can be eliminated. Such configuration will allow circuitry for determining the amount of frost formation at cooler 15 to be eliminated, thereby providing a simple configuration which is less time and cost consuming. Further, during the initial cooling after power supply, frost accumulates relatively faster and in relatively greater amount at cooler 15 because the air within refrigerator 1 to be cooled is relatively high in both temperature and humidity. Thus, it is of critical importance to sufficiently remove frost formed at cooler 15 after power supply to prevent excessive frost formation at cooler 15 and consequently preventing cooling error. In the present exemplary embodiment, controller 22 specifies the initial defrost time after power supply, in other words, initial defrost time Jl or J2 for initial defrosting to be less than the defrost time specified in the subsequent defrost cycles, in other words, normal defrost time J3 for normal defrosting under steady state. Thus, refrigerator 1 may make the transition to the normal and steady state control after frost formed during initial cooling is sufficiently removed by the initial defrosting to prevent excessive frost formation at cooler 15 and consequently preventing cooling error. Further, the above arrangement will not require frequent defrost execution when cooler 15 is running under steady state, thereby preventing temperature elevation within the refrigerator by excessive defrosting at cooler 15. Next, a description will be given on a second exemplary embodiment of the present invention with reference to FIGS. 4 and 5. The second exemplary embodiment differs from the first exemplary embodiment in that refrigerator 31 is provided with two coolers as compared to only one provided in refrigerator 1 of the first exemplary embodiment. FIG. 4 is a vertical cross sectional side view of refrigerator 31. Refrigerator 31 is provided with an exterior housing 33 made of copper plate and inner housing 34 made of plastic. By filling heat insulative material 35 such as hard urethane foam or vacuum heat insulative material between exterior housing 33 and inner housing 34, heat insulation is provided between the refrigerator interior and the refrigerator exterior. Such heat insulative configuration is collectively referred to as heat insulative cabinet 32. The interior of heat resistive cabinet 32, or the refrigerator interior, is delimited into compartments of by heat resistive partition 32a, in which the lower compartment constitutes chiller 36 and the upper compartment constitutes freezer 37. The front faces of chiller 36 and freezer 37 are enclosed by double doors 40 that are configured openable and closable. As also shown in FIG.5, between chiller 36 and freezer 37, sub-freezer 38 and ice cube chamber 39 are provided side by side in the lateral direction. On the front faces of freezer 37, sub-freezer 38 and ice cube chamber 39, a drawer style doors 41, 42, and 43 are provided respectively. As shown in FIG.4, on the left inner wall of chiller 36, control panel 44 is provided for setting the chilling and cooling temperatures. Further, on the rear wall of chiller 36, cooling chamber 45 is provided. Within cooling chamber 45, cooler 46 and cooling fan 47 are provided for cooling chiller 36. In the proximity of cooler 46, defrost heater 48 is provided for melting the frost formed at cooler 46. Provided further at cooler 46 is cooler temperature sensor 49 for sensing the temperature of cooler 46. When cooling fan 47 is driven, the cool air generated by cooler 46 is supplied into chiller 36 from cooling chamber 45 and thereafter circulated back into cooling chamber 45. Chiller 36 is cooled to the preset chilling temperature by the above described configuration. On the rear wall of freezer 37, cooling chamber 50 is provided which further contains cooler 51 and cooling fan 52 for cooling freezer 37, sub-freezer 38, and ice cube chamber 39. In the proximity of cooler 51, defrost heater 53 is provided for melting the frost formed on cooler 51. Provided further on cooler 51 is cooler temperature sensor 54 for sensing the temperature of cooler 46. When cooling fan 52 is driven, the cool air generated by cooler 51 is supplied into freezer 37, sub-freezer 38, and ice cube chamber 39 from cooling chamber 50 and thereafter circulated back into cooling chamber 50. Freezer 37, sub-freezer 38, and ice cube chamber 39 are cooled to the preset freezing temperature by the above described configuration. At the rear side lower portion of refrigerator 31, machine chamber 55 is provided that contains controller 56 that controls the overall operation of refrigerator 31. Controller 56 controls defrosting of cooler 46 and cooler 51 according to a control substantially the same as the first exemplary embodiment. That is, controller 56 sets the. initial defrost time when the temperature of cooler 4 6 sensed by temperature sensor 49 upon power supply is lower than the predetermined temperature to be less or shorter than the initial defrost time when the temperature of cooler 46 sensed by temperature sensor 49 upon power supply is higher than the predetermined temperature. Likewise, controller 56 specifies the initial defrost time when the temperature of cooler 51 sensed by temperature sensor 54 upon power supply is lower than the predetermined temperature to be less or shorter than the initial defrost time specified when the temperature of cooler 51 sensed by temperature sensor 54 upon power supply is higher than the predetermined temperature. Further, controller 56 specifies the initial defrost time after power supply for the two coolers 46 and 51 to be less or shorter than the defrost time in the subsequent defrost cycles. Since two coolers are provided in refrigerator 31 according to the second exemplary embodiment, the amount of frost formation per cooler is reduced compared to the refrigerator provided with only one cooler to render coolers 46 and 51 to be less susceptible to excessive frost formation. Further, because the amount of frost formation at coolers 4 6 and 51 can be reduced, there is relatively greater likelihood of the temperatures at cooler 4 6 and 51 at the time of power supply being higher than the predetermined temperature. Thus, the initial defrost time for coolers 46 and 51 respectively can be set at a relatively greater or longer time span, thereby allowing sufficient initial cooling of coolers 46 and 51. The present invention is not limited to the above described exemplary embodiments but may be modified or expanded as follows . The predetermined temperature, the initial defrost time, and the normal defrost time may be modified as required. In the above described exemplary embodiments, the initial defrost time has been specified on the basis of whether the detected cooler temperature is equal to or lower than the predetermined temperature and whether the detected cooler temperature is higher than the predetermined temperature. More specifically, relatively shorter initial defrost time is specified when the detected cooler temperature is equal to or lower than the predetermined temperature whereas relatively longer initial defrost time is specified when the detected cooler temperature is higher than the predetermined temperature. Alternatively, the initial defrost time may be specified in the same manner based on various other judgment basis besides those described above, for instance, whether the detected cooler temperature is lower than the predetermined temperature and ! whether the detected cooler temperature is equal to or higher ; than the predetermined temperature. j Controller 22 may indirectly determine the presence/absence of frost formation at the coolers or the amount j of frost formation based on the temperatures inside the chambers j within the refrigerator sensed by the temperature sensors such \ as freezer temperature sensor 14 that sense chamber temperatures I and set the initial defrost time based on the result of the l determination. I t The present invention may also be applied to refrigerators I provided with more than two coolers. The present invention may | I further be employed in appliances dedicated to refrigeration | purposes only or freezing purposes only instead of the above i j described refrigerators 1 and 31 that are capable of both « refrigeration and freezing. The foregoing description and drawings are merely : illustrative of the principles of the present disclosure and are ; not to be construed in a limited sense. Various changes and s i modifications will become apparent to those of ordinary skill | I f 8 I I j t in the art. All such changes and modifications are seen to fall within the scope of the disclosure as defined by the appended claims. What is claimed is: 1. A refrigerator, comprising; a cooler that cools an interior of the refrigerator; an accumulator that accumulates cooling time for cooling the interior of the refrigerator by the cooler; a defrost controller that periodically defrosts the cooler whenever the accumulated cooling time accumulated by the accumulator reaches a defrost time; a temperature detector that detects temperature of the cooler; a specifier that specifies the defrost time for an initial defrost cycle after power supply at an initial defrost time determined based on the temperature of the cooler detected by the temperature detector upon power supply; wherein, the specifier specifies the initial defrost time when the temperature of the cooler detected by the temperature detector upon power supply is lower than a predetermined temperature to be less than the initial defrost time when the temperature of the cooler detected by the temperature detector upon power supply is higher than the predetermined temperature. 2. The refrigerator according to claim 1, wherein the specifier specifies the initial defrost time to be less than the defrost time of subsequent defrost cycles. 3. The refrigerator according to claim 1, wherein at least two coolers are provided. 4. The refrigerator according to claim 2, wherein at least two coolers are provided. |
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| Patent Number | 269721 | |||||||||||||||
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| Indian Patent Application Number | 2613/CHE/2009 | |||||||||||||||
| PG Journal Number | 45/2015 | |||||||||||||||
| Publication Date | 06-Nov-2015 | |||||||||||||||
| Grant Date | 03-Nov-2015 | |||||||||||||||
| Date of Filing | 28-Oct-2009 | |||||||||||||||
| Name of Patentee | KABUSHIKI KAISHA TOSHIBA | |||||||||||||||
| Applicant Address | 1-1, SHIBAURA 1-CHOME, MINATO-KU, TOKYO 105-8001. | |||||||||||||||
Inventors:
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| PCT International Classification Number | BO5B 5/057;F25D23/00 | |||||||||||||||
| PCT International Application Number | N/A | |||||||||||||||
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