Abstract:
The present disclosure suggests a dryer and method of controlling the same. Disclosed is a dryer, comprising: a heater for heating the air which is to be directed to a dry drum; a motor for rotating the dry drum; a power supply unit for supplying electric current to the heater and the motor; a heater relay for selectively applying electric current to the heater; a motor relay for selectively applying electric current to the motor; a safety relay for selectively applying electric current from the power supply unit to the respective relay; and a control unit for cutting off electric current by turning off the safety relay when an abnormal stop occurs, after the control unit determines whether the abnormal stop occurs during a drying operation.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present disclosure relates to subject matter contained in priority Korean Application No. 10-2006-0098068, filed on Oct. 9, 2006, which is herein expressly incorporated by reference in its entirety. 
     BACKGROUND 
     The present disclosure relates to a dryer and method of controlling the same. 
     Generally, a drum-type dryer is designed to perform the drying operation while rotating laundry loaded in a dry drum. The laundry rotates and drops by the rotation of the dry drum. 
     Further, High-temperature dry air inhaled into the dry drum is mixed with the laundry to vaporize the moisture soaked in the laundry. The drum-type dryer may be classified into a condenser-type dryer and an exhaust-type dryer. The former is designed such that the air in the dry drum is directed to a condenser and a heater and is then returned to the dry drum. That is, the air circulates in the dryer without being exhausted out of the dryer. The latter is designed such that the air in the dry drum is directed to the condenser so that the moisture contained in the air can be eliminated and is then exhausted out of the dryer. 
     Particularly, according to the condenser-type dryer, the air circulating in the dryer absorbs the moisture from the laundry loaded in the drum and then passes through the condenser to be lowered in its temperature by a heat-exchange. As the temperature of the air is lowered, the moisture contained in the air is condensed. The condensed water is pumped out by a condensing pump and is then exhausted to outside. On the other hand, according to the exhaust-type dryer, high-temperature high-moisture air absorbing moisture from the laundry in the drum is exhausted out of the dryer via a lint filter. 
     Here, both of the exhaust-type and condenser type dryers are the same in that heat-exchange between the high-temperature dry air and the laundry is incurred as the laundry lifts and drops by the rotation of the drum. 
     In addition, the dryer may be classified into an electric dryer and a gas dryer depending on how to heat up the air which is to be supplied into the dry drum. That is, the dryer is classified into an electric dryer which heats the air by using an electric heater, and a gas dryer which heats the air through gas combustion. 
     Meanwhile, according to the electric dryer, a plurality of different heaters are installed in a drying duct, wherein a high-temperature heater which generates high calories and a low-temperature heater which generates low calories are installed therein. 
     Particularly, the high and low temperature heaters repeat on/off simultaneously or individually when the dry operation is performed, thereby controlling an inside of the dry drum to be maintained at a preset temperature. 
     Further, an electric leakage breaker is provided in the conventional electric dryer. And, the electric leakage breaker detects the leakage current greater than at least 25 mA. 
     On the contrary, according to the conventional dryer, the leakage current of 5 mA is generated when the dryer is abnormally stopped, and therefore the insulation of the heater is broken due to the moisture inside the dryer, however the electric leakage breaker does not detect the leakage current. In this case, there is a risk of electric shock if a user touches the dryer. 
     SUMMARY 
     The present embodiment suggests a dryer and method of controlling the same. In accordance with the embodiments of the invention, there is provided a dryer, including, a heater for heating the air which is to be directed to a dry drum; a motor for rotating the dry drum; a power supply unit for supplying electric current to the heater and the motor; a heater relay for selectively applying electric current to the heater; a motor relay for selectively applying electric current to the motor; a safety relay for selectively applying electric current from the power supply unit to the respective relay; and a control unit for cutting off electric current by turning off the safety relay when an abnormal stop occurs, after the control unit determines whether the abnormal stop occurs during a drying operation. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present embodiment will be more fully understood with reference to the accompanying drawings. 
         FIG. 1  is a cross-sectional view showing a structure of a dryer according to the present embodiment. 
         FIG. 2  is a block diagram showing a system of a dryer for embodying the concept of the present embodiment. 
         FIG. 3  is a circuit diagram of a dryer according to the present embodiment. 
         FIG. 4  is a flow chart showing a method of controlling a dryer according to the present embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, the present embodiment will be described by way of illustrative examples with reference to the accompanying drawings. 
       FIG. 1  schematically shows a cross-sectional view of a structure of a dryer according to the present embodiment. Hereinafter, the condenser-type dryer will be explained as a preferred embodiment. 
     Referring to  FIG. 1 , the dryer  10  according to the preferred embodiments of the present invention includes a cabinet  11  forming an exterior, a front frame  22  and a front cover  23  which are connected to a front of the cabinet  11 , a cylindrical drum  12  formed inside the cabinet  11 , a door  13  opening/closing an inlet of the drum  12  as it is mounted on a front portion of the drum  12 , a belt  21  rotating the drum  12  as it is surrounded around an outer circumference of the drum  12 , and a drum support  24  allowing a rear of the drum  12  to be supported on the cabinet  11 . Here, the front portion of the drum  12  is supported by the front cover  23 . 
     In addition, the dryer  10  further includes a motor shaft  171  connected with the belt  21 , a motor  17  applying a rotational force to the belt  21  as it is connected with the motor shaft  171 , and a cooling fan  16  inhaling indoor air as it is rotated by receiving the rotational force. 
     In addition, the dryer  10  further includes a drying fan  18  circulating the air inside the drum as it is connected with the motor shaft  171  at an opposite side of the cooling fan  16 , and a drying duct  19  transporting the air inhaled by the drying fan  18  to the drum  12 , in which a heater  20  is installed. 
     In addition, the dryer  10  further includes a door lint filter  14  which is formed in a rear of the door  13  to filter fluffs in humid air which is discharged from the drum  12 , a body lint filter  151  for filtering the humid air which is passed through the door lint filter  14 , and a circulation duct  15  through which the air passed through body lint filter  151  moves to a condenser (not shown). 
     In addition, the heater  20  includes a high-temperature heater  201  generating heat of approximately 1750 W, and a low-temperature heater  202  generating heat of approximately 750 W. Further, a high-temperature sensor  26  for sensing the temperature of the air which passes through the drying duct  19  is mounted on the surrounding of the heater  20 , i.e. the rear of the dry drum  12 , and a low-temperature sensor  27  for sensing the temperature of the humid air which passes through the dry drum  12  is mounted on the front of the dry drum  12 . Here, various kinds of sensor can be applied as the temperature sensor, for example a thermistor which changes its resistance in accordance with a change in temperature can be used therein. 
     Hereinafter, the operation of the dryer will be described. 
     First, if electric power is applied to the dryer, the motor  17  starts to rotate and the heater  20  attached to the inside of the drying duct  19  generates heat. After that, the drum  12  is rotated by the rotation of the belt  21  connected to the motor shaft  171 . Particularly, the drum  12  rotates about the drum support  24  as a rotation axis. Further, a dry object in the drum  12  rotates along an inner wall of the drum  12  as the drum  12  rotates, and drops by self-weight at a top of the drum. Here, the dry object is raised by a lifter (not shown) disposed at the inner wall of the drum  12 . 
     Meanwhile, the drying fan  18  connected to the motor shaft  171  is operated at the same time of the rotation of the motor  17 , to inhale the circulation air passed through the condenser. The inhaled circulation air rises along the drying duct  19  and becomes a high-temperature and dry air via the heater  20 . Further, the high-temperature and dry circulation air passes through the drum  12  while absorbing the moisture from the dry object, and thus, it becomes a high-temperature and humid air. 
     In addition, the high-temperature and humid air is again filtered by the door lint filter  14  and the body lint filter  151 , and then is directed to the condenser along the circulation duct  15 . 
     In addition, when the cooling fan  16  connected to the motor shaft  171  is rotated to inhale the indoor air out of the dryer. And then, the inhaled indoor air is flowed to the condenser through the cooling fan  16 . 
     Here, the high-temperature and humid air flowed along the circulation duct  15  and the indoor air inhaled by the cooling fan  16  are passed through the condenser with being crossed to each other. Also, the high-temperature and humid air and the indoor air just exchange heat, not being mixed due to the configuration of the condenser. 
     Therefore, the high-temperature and humid air is deprived of heat by the indoor air while passing through the condenser, thereby being changed into a low-temperature and humid air. In addition, as temperature is lowered, moisture contained in the air is condensed and dropped down onto the bottom of the condenser, and then flowed to a sump (not shown) where the condensed water is collected. 
       FIG. 2  shows a block diagram of a system of a dryer according to the preferred embodiments of the present invention, and  FIG. 3  shows a circuit diagram of a dryer according to the preferred embodiments of the present invention. 
     Referring to  FIG. 2 , the system of the dryer according to the preferred embodiments of the present invention includes a control unit  100 , a key input unit  110  for inputting dry conditions and operation commands, a driving unit  130  driving the heater  20  or the motor  17  depending on the input dry condition, and a temperature sensor for sensing the temperature of the air which is heated by the heater  20 , wherein the temperature sensor includes a high-temperature sensor  26  and a low-temperature sensor  27 . 
     In addition, the system of the dryer includes a safety relay  140  which cut off the electric current due to the malfunction of the dryer, and a memory  120  in which various information such as the command information input by the key input unit  110  and the temperature information transmitted from the temperature sensors  26 ,  27  are stored. 
     Referring to  FIG. 3 , the dryer according to the preferred embodiments of the present invention intermittently transmits the electric current from the power supply unit  180  to the driving unit via the safety relay  140 . 
     Further, the on/off of the high and low temperature heaters  210 ,  220  are controlled by a high-temperature heater relay  150  and a low-temperature heater relay  160 , respectively. The on/off of the motor  17  is controlled by a motor relay  170 . And, the high-temperature heater relay  150 , the low-temperature heater relay  160  and the motor relay  170  are parallel connected to the safety relay  140 . 
     Therefore, the high and low temperature heaters  210 ,  220  and the motor  17  are turned on/off by the respective relay  150 ,  160 ,  170 , independently. And, if the safety relay  140  is turned off, then all of the high and low temperature heaters  210 ,  220  and the motor  17  are turned off. 
       FIG. 4  shows a flow chart of a method of controlling a dryer according to the preferred embodiments of the present invention. 
     Referring to  FIG. 4 , dry conditions are input by a key input unit (S 110 ), and operation commands are input by a operation button (S 111 ). 
     Particularly, if the operation commands are input, electric current is applied into the dryer and the safety relay  140  is turned on (S 112 ). And, the motor  17  and the high and low temperature heaters  210 ,  220  are turned on. And, the motor  17  is rotated at a preset speed according to the input dry conditions, and the high and low temperature heaters  210 ,  220  are repeatedly turned on/off to maintain the inside of the drum at a preset temperature. 
     Meanwhile, the control unit  100  determines in real time whether an abnormal stop, such as a stop command is input by the user or an overheating in the dry drum is occurred because the filter is blocked, is occurred or not (S 114 ). 
     If the abnormal stop does not occur during the whole drying operation, the drying operation is processed according to the input dry condition (S 200 ). And, the operation of the dryer stops or continues after determining whether the drying operation is completed or not (S 201 ). 
     On the other hand, the abnormal stop is occurred during the drying operation, the high temperature heater is previously turned off (S 115 ), and the low-temperature heater is turned off (S 116 ). And, after the motor is finally stopped (S 117 ), the safety relay  140  is turned off (S 118 ). And, if the cause of the abnormal stop is determined by the control unit  100  to be solved (S 119 ) after determining whether the cause is solved or not, the drying operation is normally carried out (S 200  and below steps are carried out) according to the input dry condition. 
     However, if the cause of the abnormal stop is not solved, the operation of the dryer is terminated. Here, the expression “the cause of the abnormal stop is solved” means that the user re-presses the operation button after pressing the stop button, or that the user cleans the filter after he/she recognizes a filter block signal. 
     As described in the above description, the electric current, which is to be supplied into the power supply unit  180 , is prevented from being leaked out by stopping the heater and the motor as well as by turning off the safety relay  140  when the abnormal stop is occurred. Therefore, it is possible to prevent the user from being struck by the electric current leaked around the surface of the dryer.