Abstract:
The present invention relates to temperature control for refrigerators, which automatically adjusts the on-temp/off-temp values in view of the fluctuation of the ambient temperature. The present invention also relates to a refrigerator on which a sensor of simplified circuit design is reasonably allocated. In accordance with the present invention, ambient temperature is divided into a plurality of particular temperature divisions, the on-temp and off-temp values preferred for refrigerator operation in each corresponding temperature division are determined by experiments. By means of a temperature sensor, on-temp/off-temp values appropriately corresponding to a particular temperature division are applied to keep the temperature of the refrigerator at a required level.

Description:
TECHNICAL FIELD 
     The present invention generally relates to appliance and, more particularly, to refrigerators and temperature control for the same. 
     BACKGROUND 
     Up to the present invention, temperature control for refrigerators was done manually. Once the temperature settings of a regulator or computer panel for refrigerators&#39; temperature control has been determined, temperature values for turning the refrigerator on/off are fixed. The values remain unchanged no matter the ambient temperature has changed. It would be fine in a situation that the ambient temperature is changed in a narrow range. However, if the ambient temperature changes significantly, the fixed values may not keep the temperature in the refrigerator at a required level. As a result, the food in the refrigerator becomes either defrozen as the temperature in the refrigerator is too high or over frozen as the temperature in the refrigerator is too low. Either of both eases is adverse for food reservation. 
     DESCRIPTION 
     One objective of the present invention is to provide a temperature control for refrigerators, which may automatically regulate values for turning the refrigerator on/off as the ambient temperature varies. 
     Another objective of the present invention is to provide a simply designed refrigerator with a reasonably allocated environment sensor. 
     In accordance with the present invention, a method for temperature control comprises steps of defining at least a first temperature division and a second temperature division of ambient temperature and determining first on-temp/off-temp values for turning on/off the refrigerator in said first temperature division and second on-temp/off-temp values for turning on/off the refrigerator in said second temperature division; detecting and transferring ambient temperature signals to a control processor; enabling the on-temp/off-temp values by the control processor in response to received ambient temperature signals; determining in response to the ambient temperature signals whether variation of the ambient temperature is within the first temperature division and adjusting the first on-temp/off-temp values to the second on-temp/off-temp values if the ambient temperature changes from the first temperature division to the second temperature division. 
     In accordance with the present invention, the on values corresponding to a plurality of temperature divisions are consistent while the off-temp values are changed. Furthermore, a plurality of temperature division has correspondent on-temp/off-temp values as follows: 
     
       
         
               
               
               
             
           
               
                   
               
               
                 Temperature 
                   
                   
               
               
                 Division ° C. 
                 On-Temp Value ° C. 
                 Off-Temp Value ° C. 
               
               
                   
               
             
             
               
                 [−60, −2) 
                 4 
                 −25 ˜ −30 
               
               
                 [−2, 5) 
                 4 
                 −21 ˜ −26 
               
               
                 [5, 14) 
                 4 
                 −19 ˜ −23 
               
               
                 [14, 21) 
                 4 
                 −18 ˜ −21 
               
               
                 [21, 28) 
                 4 
                 −17 ˜ −19 
               
               
                 [28, 36) 
                 4 
                 −16 ˜ −18 
               
               
                 [36, +60) 
                 4 
                 −15 ˜ −17 
               
               
                   
               
             
          
         
       
     
     The present invention provides a refrigerator comprising a shell and a control processor. A sensor is set up at the rear top of the shell, in particular, a position for separating the cooling source from the heating source. The sensor is coupled to the input of the control processor which outputs are coupled to a heater and a compressor respectively. 
     In accordance with the present invention, the sensor is connected to a power supply through a resistor and to the input of the control processor through a capacitor The sensor is grounded directly. The input of the control processor is connected to the power supply through a resistor and a capacitor. 
     Furthermore, the heater is connected across the power supply and in series with the normal-on switch of a relay that is connected in parallel with a diode. The output of the control processor is connected to the base of a transistor through a resistor. The emitter of the transistor is grounded while the collector of the transistor is connected to the power supply. 
     Moreover, the compressor is connected across the power supply and in series with the normal-on switch of the relay that is connected in parallel with a diode. The output of control processor is connected to the base of the transistor. The emitter of the transistor is grounded while the collector of the transistor is connected to the power supply. 
     The advantages and essential effects of the invention are that with location of the sensor in the rear shell top of ale refrigerator, neither cooling source nor heating source all around, thereby minimizing the disturbance to the operation of the sensor. In accordance with a preferred embodiment of the present invention, a particular temperature division is determined [21, 28) at ambient temperature of 25° C. so the on-temp value should be 4° C. and the off-temp value −18° C. With these on-temp and off-temp values in this particular division, the temperature of the storage compartment in the refrigerator is maintained within a range of 4° C.˜7° C. while the temperature of the freezing compartment is stabilized under −18° C. When the ambient temperature fluctuates in 21° C.˜28° C., the on-temp value is still +4° C. and the off-temp value of −18° C. remains unchanged, so the temperature in the refrigerator keeps unchanged also. When the ambient temperature drops to about +18° C., the sensor detects the current temperature and sends a detecting signal to the control processor that determines the current ambient temperature in the temperature division [14, 21), thereby automatically setting up the on-temp value at 4° C. and the off-temp value at −19° C. Accordingly, the refrigerator operates under such conditions, keeping the temperature in the refrigerator unchanged. 
    
    
     BRIEF ILLUSTRATION OF DRAWINGS 
     FIG. 1 shows the location of the sensor in accordance with the present invention; 
     FIG. 2 is a circuit diagram of the sensor in accordance with the present invention; and 
     FIG. 3 is a block diagram of the program segment of the control processor in relation to the sensor. 
    
    
     PREFERRED EMBODIMENTS 
     As shown in FIG.  1  and FIG. 2, temperature control for refrigerators comprises following steps: 
     a) defining at least one first temperature division and one second temperature division of ambient temperature and determining first on-temp/off-temp values for turning on/off the refrigerator in said first temperature division and second on-temp/off-temp values for turning on/off the refrigerator in said second temperature division; 
     b) detecting and transferring ambient temperature signals to a control processor; 
     c) enabling the on-temp/off-temp values by the control processor in response to received ambient temperature signals; 
     d) determining in response to the ambient temperature signals whether variation of the ambient temperature is within the first temperature division and adjusting the first on-temp/off-temp values to the second on-temp/off-temp values if the ambient temperature changes from the first temperature division to the second temperature division. 
     In light of the reality of operation of a refrigerator, the on-temp value is normally consistence, so the on-temp values in accordance with the present invention remain constant while the off-temp values are appropriately varied corresponding to each of temperature divisions. Based upon experiments and practice, the data with respect to the particular temperature divisions and the on-temp and off-temp values corresponding to the respective temperatures are listed as follows: 
     
       
         
               
               
               
             
           
               
                   
               
               
                 Temperature 
                   
                   
               
               
                 Division ° C. 
                 On-Temp Value ° C. 
                 Off-Temp Value ° C. 
               
               
                   
               
             
             
               
                 [−60, −2) 
                 4 
                 −30 
               
               
                 [−2, 5) 
                 4 
                 −25 
               
               
                 [5, 14) 
                 4 
                 −21 
               
               
                 [14, 21) 
                 4 
                 −19 
               
               
                 [21, 28) 
                 4 
                 −18 
               
               
                 [28, 36) 
                 4 
                 −17 
               
               
                 [36, +60) 
                 4 
                 −16 
               
               
                   
               
             
          
         
       
     
     In accordance with the data listed above, the control processor is programmed to perform its control task. 
     FIG. 3 shows the flow chart of the control program. The code of the program is written by C-language and listed as follows: 
     
       
         
               
               
               
               
             
           
               
                   
                   
               
             
             
               
                   
                 LCZHHT 
                 MOVLW 
                 OAAU 
               
               
                   
                   
                 SUBWF 
                 TXH, 0 
               
               
                   
                   
                 BTFSS 
                 STATUS, 2 
               
               
                   
                   
                 GOTO 
                 LCZH3 
               
               
                   
                 LCZHHT1 
                 BCF 
                 FLAG1, 1 
               
               
                   
                   
                 BCF 
                 FLAG2, 2 
               
               
                   
                   
                 BCF 
                 FLAG6, 2 
               
               
                   
                   
                 BCF 
                 FLAG6, 3 
               
               
                   
                   
                 BCF 
                 FLAG3, 3 
               
               
                   
                   
                 BCF 
                 FLAG6, 6 
               
               
                   
                   
                 BCF 
                 FLAG6, 7 
               
               
                   
                   
                 CLRF 
                 SDT 
               
               
                   
                   
                 CLRF 
                 SD 
               
               
                   
                   
                 MOVLW 
                 OD2H 
               
               
                   
                   
                 SUBWF 
                 HT, 0 
               
               
                   
                   
                 BTPSC 
                 STATUS, 0 
               
               
                   
                   
                 GOTO 
                 SETID 
               
               
                   
                   
                 BCF 
                 FLAGA, 1 
               
               
                   
                   
                 ;; BTFSC 
                 FLAGA, 2 
               
               
                   
                   
                 ;; GOTO 
                 ZhHT 
               
               
                   
                   
                 MQVLW 
                 OC5H 
               
               
                   
                   
                 SUBWF 
                 HT, 0 
               
               
                   
                   
                 BTFSC 
                 STATUS, 0 
               
               
                   
                   
                 GOTO 
                 SET2D 
               
               
                   
                 ZHHT5 
                 BCF 
                 FLAGA, 2 
               
               
                   
                   
                 ;; BTFSC 
                 FLAGA, 3 
               
               
                   
                   
                 ;; GOTO 
                 ZHHT1 
               
               
                   
                   
                 MOVLW 
                 OAFH. 
               
               
                   
                   
                 SUBWF 
                 HT, 0 
               
               
                   
                   
                 BTFSC 
                 STATUS, 0 
               
               
                   
                   
                 GOTO 
                 SET3D 
               
               
                   
                 ZHHT6 
                 BCF 
                 FLAGA, 3 
               
               
                   
                   
                 ;; BTFSC 
                 FLAGA, 4 
               
               
                   
                   
                 ;; GOTO 
                 ZHHT2 
               
               
                   
                   
                 MOVLW 
                 099H 
               
               
                   
                   
                 SUBWF 
                 HT, 0 
               
               
                   
                   
                 BTFSC 
                 STATUS, 0 
               
               
                   
                   
                 GOTO 
                 SET4D 
               
               
                   
                   
                 BCF 
                 FLAGA, 4 
               
               
                   
                   
                 ;; BTFSC 
                 FLAGA, 5 
               
               
                   
                   
                 ;; GOTO 
                 ZHHT3 
               
               
                   
                   
                 MOVLW 
                 089H 
               
               
                   
                   
                 SUBWF 
                 HT, 0 
               
               
                   
                   
                 BTFSC 
                 STATUS, 0 
               
               
                   
                   
                 GOTO 
                 SET5D 
               
               
                   
                 ZHHT8 
                 BCF 
                 FLAGA, 5 
               
               
                   
                   
                 ;; BTFSC 
                 FLAGA,6 
               
               
                   
                   
                 ;; GOTO 
                 ZHHT4 
               
               
                   
                   
                 MOVLW 
                 073H 
               
               
                   
                   
                 SUBWF 
                 HT, 0 
               
               
                   
                   
                 BTFSC 
                 STATUS, 0 
               
               
                   
                   
                 GOTO 
                 SET6D 
               
               
                   
                 ZHHT9 
                 CLRF 
                 FLAGA 
               
               
                   
                   
                 BSF 
                 FLAGA, 7 
               
               
                   
                   
                 MOVLW 
                 001H 
               
               
                   
                   
                 MOVLW 
                 SRT 
               
               
                   
                   
                 MOVLW 
                 RD 
               
               
                   
                   
                 ; BCF 
                 FLAG1, 3;; 
               
               
                   
                   
                 RETURN 
               
               
                   
                 SET1D 
                 MOVLW 
                 007H 
               
               
                   
                   
                 MOVWF 
                 SRT 
               
               
                   
                   
                 MOVWF 
                 RD 
               
               
                   
                   
                 CLRF 
                 FLAGE 
               
               
                   
                   
                 BSF 
                 FLAGE, 1 
               
               
                   
                   
                 RETURN 
               
               
                   
                 SET2D 
                 MOVLW 
                 006H 
               
               
                   
                   
                 MOVWF 
                 SRT 
               
               
                   
                   
                 MOVWF 
                 RD 
               
               
                   
                   
                 CLRF 
                 FLAGE 
               
               
                   
                   
                 BSF 
                 FLAGE, 2 
               
               
                   
                   
                 RETURN 
               
               
                   
                 SET3D 
                 MOVLW 
                 005H 
               
               
                   
                   
                 MOVWF 
                 SRT 
               
               
                   
                   
                 MOVWF 
                 RD 
               
               
                   
                   
                 CLRF 
                 FLAGE 
               
               
                   
                   
                 BSF 
                 FLAGE, 3 
               
               
                   
                   
                 RETURN 
               
               
                   
                 SET4D 
                 MOVLW 
                 004H 
               
               
                   
                   
                 MOVWF 
                 SRT 
               
               
                   
                   
                 MOVWF 
                 RD 
               
               
                   
                   
                 CLRF 
                 FLAGE 
               
               
                   
                   
                 BSF 
                 FLAGE, 3 
               
               
                   
                   
                 RETURN 
               
               
                   
                 SET5D 
                 MOVLW 
                 003H 
               
               
                   
                   
                 MOVWF 
                 SRT 
               
               
                   
                   
                 MOVWF 
                 RD 
               
               
                   
                   
                 CLRF 
                 FLAGE 
               
               
                   
                   
                 BSF 
                 FLAGE, 5 
               
               
                   
                   
                 RETURN 
               
               
                   
                 SET6D 
                 MOVLW 
                 002H 
               
               
                   
                   
                 MOVWF 
                 SRT 
               
               
                   
                   
                 MOVWF 
                 RD 
               
               
                   
                   
                 CLRF 
                 FLAGE 
               
               
                   
                   
                 BSF 
                 FLAGE, 6 
               
               
                   
                   
                 RETURN 
               
               
                   
                   
               
             
          
         
       
     
     In order to utilize the temperature control, modification has to be made to regular refrigerators. A regular refrigerator has to have a shell and a processor that actually is a control chip sensor HT is set up at the rear shell top of the refrigerator where is a cooling source is separated from a heating source. The sensor is coupled to the input RA3.5 of the processor while tie output RC0 of the processor is connected to a heater and output RA5 to a compressor. 
     The processor is a 16C73B chip. Its pin  1  MCLR is grounded by capacitor C 3  of 104F capacitance. Pin  1  also is connected to a resistor R 3  of 1K resistance. Resistor R 3  is connected to the power supply through a 10K resistor R 2  and a diode D 6 . The power supply is grounded through a IN4003 reverse diode D 6  and a 4.7 μF/16V capacitor E 3 . The processor has its VSS and RA4.6 connected in common to VDD through a 104F capacitor C 5 . The RA4.6 is also connected to VDD through a 2.2K resistor R 1  and a 4.7 μF/16V capacitor E 2 . VDD end is connected to the power supply and RA4.6 end is grounded. The sensor that may be a regular temperature sensor is connected to the power supply through a 1.5K resistor R 18 . The sensor is also connected to the input PA3.5 of the processor through a 101F capacitor C 2 . The sensor is connected to ground directly. The input RA3.5 of the processor is connected to the power supply through a 2.2K resistor R 16  and resistor R 18 . 
     The heater is in series connected to normal-on switch CH 1  of the relay across the power supply. The power supply is provided by a transformer and a stabilizer after an external power is filtered by a 104F capacitor C 1  and a 2200 UμF/25V capacitor E 1  and rectified by a bridge rectifying circuit. The output RCO of the processor is connected to the base of a S9014 type transistor N 2  through a 4.7K resistor R 15 . The emitter of the transistor N 2  is grounded while the collector is connected to the power supply through relay J 2  that is in parallel connected to an IN4003 type diode D 7 . 
     The compressor is in series connected to the normal-on switch CH 2  of the relay across the power supply. The output RA 5  of the processor is connected to the base of S9014 type transistor N 1  through a 4.7K resistor R 14 . The emitter of the transistor N 1  is grounded while the collector is connected to the power supply through a relay J 1  that is in parallel connected with an IN4003 diode D 5 .