Method of controlling a dryer

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.

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.

DETAILED DESCRIPTION

Hereinafter, the present embodiment will be described by way of illustrative examples with reference to the accompanying drawings.

FIG. 1schematically 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 toFIG. 1, the dryer10according to the preferred embodiments of the present invention includes a cabinet11forming an exterior, a front frame22and a front cover23which are connected to a front of the cabinet11, a cylindrical drum12formed inside the cabinet11, a door13opening/closing an inlet of the drum12as it is mounted on a front portion of the drum12, a belt21rotating the drum12as it is surrounded around an outer circumference of the drum12, and a drum support24allowing a rear of the drum12to be supported on the cabinet11. Here, the front portion of the drum12is supported by the front cover23.

In addition, the dryer10further includes a motor shaft171connected with the belt21, a motor17applying a rotational force to the belt21as it is connected with the motor shaft171, and a cooling fan16inhaling indoor air as it is rotated by receiving the rotational force.

In addition, the dryer10further includes a drying fan18circulating the air inside the drum as it is connected with the motor shaft171at an opposite side of the cooling fan16, and a drying duct19transporting the air inhaled by the drying fan18to the drum12, in which a heater20is installed.

In addition, the dryer10further includes a door lint filter14which is formed in a rear of the door13to filter fluffs in humid air which is discharged from the drum12, a body lint filter151for filtering the humid air which is passed through the door lint filter14, and a circulation duct15through which the air passed through body lint filter151moves to a condenser (not shown).

In addition, the heater20includes a high-temperature heater201generating heat of approximately 1750 W, and a low-temperature heater202generating heat of approximately 750 W. Further, a high-temperature sensor26for sensing the temperature of the air which passes through the drying duct19is mounted on the surrounding of the heater20, i.e. the rear of the dry drum12, and a low-temperature sensor27for sensing the temperature of the humid air which passes through the dry drum12is mounted on the front of the dry drum12. 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 motor17starts to rotate and the heater20attached to the inside of the drying duct19generates heat. After that, the drum12is rotated by the rotation of the belt21connected to the motor shaft171. Particularly, the drum12rotates about the drum support24as a rotation axis. Further, a dry object in the drum12rotates along an inner wall of the drum12as the drum12rotates, 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 drum12.

Meanwhile, the drying fan18connected to the motor shaft171is operated at the same time of the rotation of the motor17, to inhale the circulation air passed through the condenser. The inhaled circulation air rises along the drying duct19and becomes a high-temperature and dry air via the heater20. Further, the high-temperature and dry circulation air passes through the drum12while 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 filter14and the body lint filter151, and then is directed to the condenser along the circulation duct15.

In addition, when the cooling fan16connected to the motor shaft171is rotated to inhale the indoor air out of the dryer. And then, the inhaled indoor air is flowed to the condenser through the cooling fan16.

Here, the high-temperature and humid air flowed along the circulation duct15and the indoor air inhaled by the cooling fan16are 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. 2shows a block diagram of a system of a dryer according to the preferred embodiments of the present invention, andFIG. 3shows a circuit diagram of a dryer according to the preferred embodiments of the present invention.

Referring toFIG. 2, the system of the dryer according to the preferred embodiments of the present invention includes a control unit100, a key input unit110for inputting dry conditions and operation commands, a driving unit130driving the heater20or the motor17depending on the input dry condition, and a temperature sensor for sensing the temperature of the air which is heated by the heater20, wherein the temperature sensor includes a high-temperature sensor26and a low-temperature sensor27.

In addition, the system of the dryer includes a safety relay140which cut off the electric current due to the malfunction of the dryer, and a memory120in which various information such as the command information input by the key input unit110and the temperature information transmitted from the temperature sensors26,27are stored.

Referring toFIG. 3, the dryer according to the preferred embodiments of the present invention intermittently transmits the electric current from the power supply unit180to the driving unit via the safety relay140.

Further, the on/off of the high and low temperature heaters210,220are controlled by a high-temperature heater relay150and a low-temperature heater relay160, respectively. The on/off of the motor17is controlled by a motor relay170. And, the high-temperature heater relay150, the low-temperature heater relay160and the motor relay170are parallel connected to the safety relay140.

Therefore, the high and low temperature heaters210,220and the motor17are turned on/off by the respective relay150,160,170, independently. And, if the safety relay140is turned off, then all of the high and low temperature heaters210,220and the motor17are turned off.

FIG. 4shows a flow chart of a method of controlling a dryer according to the preferred embodiments of the present invention.

Referring toFIG. 4, dry conditions are input by a key input unit (S110), and operation commands are input by a operation button (S111).

Particularly, if the operation commands are input, electric current is applied into the dryer and the safety relay140is turned on (S112). And, the motor17and the high and low temperature heaters210,220are turned on. And, the motor17is rotated at a preset speed according to the input dry conditions, and the high and low temperature heaters210,220are repeatedly turned on/off to maintain the inside of the drum at a preset temperature.

Meanwhile, the control unit100determines 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 (S114).

If the abnormal stop does not occur during the whole drying operation, the drying operation is processed according to the input dry condition (S200). And, the operation of the dryer stops or continues after determining whether the drying operation is completed or not (S201).

On the other hand, the abnormal stop is occurred during the drying operation, the high temperature heater is previously turned off (S115), and the low-temperature heater is turned off (S116). And, after the motor is finally stopped (S117), the safety relay140is turned off (S118). And, if the cause of the abnormal stop is determined by the control unit100to be solved (S119) after determining whether the cause is solved or not, the drying operation is normally carried out (S200and 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 unit180, is prevented from being leaked out by stopping the heater and the motor as well as by turning off the safety relay140when 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.