Electric cooker having a composite heat source

An electric cooker having a composite heat source includes an external case having an air inlet and an air outlet, a cooking plate mounted on an upper surface of the external case to be a top plate thereof, a heat generating unit mounted between the external case and the cooking plate, the heat generating unit including a work coil and an electric heater and arranged coaxially with the air inlet with respect to a center of the air inlet, a cooling unit coaxially arranged with respect to the center of the air inlet between the air inlet and the heat generating unit, the cooling unit cooling the heat generating unit, an air duct provided below the heat generating unit, and a reflector forming an outer cover of the electric heater.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to application filed in the Korean Industrial Property Office on Dec. 8, 2005, and assigned serial No. 10-2005-0119320, the contents of which are incorporated herein by reference.

BACKGROUND

This invention relates to an electric cooker, and more particularly to an electric cooker having a composite heat source composed of an induction heating work coil and an electric heater, and still more particularly to an electric cooker improved in cooling efficiency by improvement of radiation structure.

The typical electric cooker is known as an environment-friendly product that can provide a clean and pleasant cooking environment because of being free from hazardous gas, soot, discharge of carbon monoxide and deficiency of oxygen.

The cooker is also widely used as an energy-efficient product because it takes a short time to reach a maximum thermal power by way of using a new material as heat source, and maintains a constant temperature using a temperature sensor.

An induction heating cooker which is one of the electric cookers is operated in such a manner that a magnetic field is generated by causing high-frequency current to flow through a work coil, and inducing the magnetic field into a cooking vessel, thereby generating eddy current to heat the cooking vessel. Conventionally, this type of induction heating cooker does not generate an air-polluting flame and have a high thermal efficiency, unlike a gas oven stove that heats a cooking vessel by way of oxidizing fuel. Therefore, the demand for this type of induction heating cooker is increasing.

In other words, the induction heating cooker conducts the cooking by using the heat generated by magnetic force applied to the cooking vessel. Therefore, the induction heating cooker is widely accepted as one of the excellent cookers as it generates heat for cooking by using the magnetic field, causing no air pollution and has a high energy usability of 80% or more thermal efficiency.

Meanwhile, the conventional electric cooker includes a cooking plate mounted on an external case, and a heat generating unit as a heat source provided at a bottom surface of the cooking plate. The heat generating unit may be an electric heater, or a typical flat pancake-like radially and spirally wound work coil, or may be a composite heat source using different types of heat sources including the electric heater and the work coil.

In the electric cooker disposed with a composite heat source, an internal temperature of the external case may suddenly increase due to driving heat generated by the electric heater. The rise of internal temperature can affect ambience of the work coil such that there is a need to install heat radiation means for appropriately maintaining the ambient temperature of the work coil having a limit in heat-resistance.

An external case of a typical electric cooker is disposed at an inner space thereof with an inverter (not shown) for driving a heat generating unit, a controller mounted with a driving circuit (not shown) and a cooling unit for cooling the heat generated from the heat generating unit and the controller.

The typical cooling unit of an electric cooker is disposed at one end of the external case thereof with a blowing fan for sucking outside air and blowing the air to the heat generating unit, where the introduced air is horizontally circulated in an inner space of the external case and discharged.

In the ventilation structure of the electric cooker thus explained, the outside air infused by the blowing fan disposed at one end of the external case is horizontally circulated for cooling the heat generating unit and the work coil and sequentially cools the ambient temperature of the work coil and the controller. In other words, the outside air introduced from outside by the blowing fan passes the electric heater to cool the work coil, and again passes the electric heater to cool the controller.

However, there is a disadvantage in the conventional ventilation structure thus explained in that it has a limit of cooling efficiency because the air that has passed the electric heater is used for cooling the work coil and the controller.

There is another disadvantage in that the introduced air is so configured as to horizontally go through a linear passage, making it difficult to effect a uniform cooling operation covering an entire area of the work coil and thereby decreasing the cooling efficiency.

There is still further disadvantage in that a fan of large capacity should be used to enhance the cooling efficiency of an electric cooker having a composite heat source, causing an enlarged size of the cooker and increased manufacturing cost.

SUMMARY

The present invention is disclosed to solve the afore-mentioned disadvantages of the conventional electric cooker and it is an object of the present invention to provide an electric cooker having a composite heat source configured to improve a ventilation structure for heat radiation of the electric cooker such that cooling efficiency, durability and reliability of the electric cooker can be enhanced.

It is another object of the present invention to provide an electric cooker having a composite heat source which is conducive to reducing the manufacturing cost and making a light, thin, small and compact product through configuration of a ventilation structure by which sufficient cooling efficiency can be obtained even with use of a small capacity of blowing fan.

In one general aspect, the electric cooker comprises: an external case having an air inlet and an air outlet; a cooking plate mounted on an upper surface of the external case; a heat generating unit mounted between the external case and the cooking plate for coaxial arrangement with the air inlet and for heating a cooking vessel mounted on the upper surface of the cooking plate; and a cooling unit coaxially arranged between the air inlet and the heat generating unit for cooling the heat generated by the heat generating unit via the air outlet.

The air inlet is formed as an opening on a floor of the external case and the air outlet is formed as an opening on a lateral surface of the external case.

The heat generating unit comprises: a work coil for inductively heating the cooking vessel disposed on the cooking plate; and an electric heater arranged about the work coil.

According to one embodiment of the present invention, the heat generating unit preferably comprises: a work coil for inductively heating the cooking vessel disposed on the cooking plate; an adiabatic plate disposed between the cooking plate and the work coil; an electric heater arranged about the work coil; and a reflector forming an outer cover of the electric heater.

The cooling unit comprises: a blowing fan disposed on a floor surface of the external case for being coaxially arranged between the air inlet and the heat generating unit; and an air duct so disposed as to form a passage between the blowing fan and the heat generating unit.

The air duct is a cylindrically structured body for guiding outside air introduced by the blowing fan to the heat generating unit, and is further disposed with an adiabatic duct.

DETAILED DESCRIPTION

Referring toFIGS. 1 to 3, an electric cooker1comprises; an external case10so disposed as to form a cooking plate20as a top plate; and a heat generating unit30and a cooling unit40, each unit so disposed as to be coaxially arranged between the cooking plate20and the external case10.

The external case10is disposed with an air inlet11and an air outlet12so that air can pass therethrough. The air inlet11is formed as an opening on an approximate center of the floor of the external case10. The air outlet12is formed as an opening on a lateral surface of the external case10.

The cooling unit40and the heat generating unit30in the electric cooker are sequentially arranged upwards of the air inlet11. In other words, the heat generating unit30is coaxially arranged on the air inlet11, and the cooling unit40is coaxially disposed between the air inlet11and the heat generating unit30.

The heat generating unit30is a composite heat source composed of an induction-heating work coil31and an electric heater32for heating a cooking vessel (not shown) mounted on the cooking plate20. Unexplained reference numeral33represents an adiabatic plate disposed for preventing heat generated by the electric heater32from being transmitted downwards, and34denotes a reflector.

The work coil31is disposed at a central bottom surface of the cooking plate20in the form of being wrapped up by the electric heater32.

Preferably, the electric heater32and the work coil31are elastically mounted at the bottom surface of the cooking plate20in the form of being pushed upwards by a plurality of springs (50.).

The reflector34is disposed with a groove34bfor accommodating the electric heater32, and is also formed at both ends thereof with openings for accommodating terminals34aof the electric heater32.

The electric heater32is mounted along the groove34bof the reflector34, and the terminals34aof the electric heater32are arranged at the openings of the reflector34.

The heat generated from the electric heater32is transmitted to the cooling plate20via the reflector34to heat the cooking vessel (not shown) and in addition, the work coil31may be selectively driven to heat the cooking vessel as a composite heat source.

The adiabatic plate33is disposed between the cooking plate20and the work coil31to form a disc shape The adiabatic plate33prevents the work coil31from being transmitted with heat of the electric heater32. The adiabatic plate33further prevents the cooking plate20from excessively rising in temperature by the heat of the work coil31.

The cooling unit40includes a blowing fan41and an air duct42for cooling the heat generated by the heat generating unit30. The blowing fan41is supportively disposed on the floor of the external case10for being coaxially arranged upwards of the air inlet11, and the blowing fan is mounted thereon with the heat generating unit30.

The air duct42is a cylindrically structured body for forming a passage between the blowing fan41and the heat generating unit30and for guiding outside air introduced by the blowing fan41into the air inlet11to the heat generating unit30.

According to one general aspect of the present invention, the air duct42may be further coaxially disposed thereabout with an adiabatic duct43.

The adiabatic duct43guides in such a manner that the outside air having passed downstream of the air duct42is circulated along the passage formed between the work coil31and the electric heater32and the passage formed between the terminals34aof the electric heater32to exit via the air outlet12. Furthermore, the adiabatic duct43functions to prevent inside air of the external case10and the air introduced via the air duct42from being heat-exchanged.

Now, heat-radiating operation of the electric cooker thus configured according to the present invention will be described in detail with reference to the accompanying drawings.

If the electric cooker1is operated by a user, an electric power is applied to the heat generating unit30by a control signal of a controller (not shown) to start to heat the cooking vessel (not shown) mounted on the cooking plate20. At this time, configuration of the electric cooker may be arranged in such a fashion that the power is applied to either an induction-heating work coil131or an electric heater132, or the power is applied to both the work coil131and the heater132according to selection of operation mode by the user.

Meanwhile, the blowing fan41of the cooling unit40may be controlled in cooperation with the operation of the heat generating unit30. Alternatively, the blowing fan41of the cooling unit40may be controllably driven independent of the operation of the heat generating unit30according to selective operation and need of the user.

Now, hereinafter, operation of the cooling unit40, particularly, the operation for radiation of heat from the electric cooker will be described in detail.

The outside air infused into the air duct42via the air inlet11of the external case10cools the heat generated by the heat generating unit30with respect to rotational driving of the blowing fan41, and is discharged to the outside via the air outlet12formed at the lateral surface of the external case10. In the circulation structure thus described, the blowing fan41functions to conduct the circulating operation where the outside air is forcibly introduced into the air duct42via the air inlet11, and is forcibly blown to heat generating unit30for discharge via the air outlet12.

In other words, the heat generating unit40vertically induces the outside air sucked via the air inlet11by the operation of the blowing fan41and the air duct42and allows the air to first contact the work coil31.

Successively, the air is induced to flow along the passage formed between the work coil31and the electric heater32and the passage formed between the terminals34aof the electric heater32and to be discharged to the outside via the air outlet12, thereby making it possible to concentratively cool the heat produced by the heat generating unit30.

In the cooling process thus described, the adiabatic duct43prevents the air introduced from the outside from escaping to a space other than that formed by the terminals34aof the electric heater32.

In other words, the adiabatic duct43serves to guide the air raised by the blowing fan41toward the work coil31and the terminals34aof the electric heater32, and simultaneously to block the heat generated by the electric heater32, thereby producing no effect on the work coil31.

This is necessitated by the fear that the work coil31, made of Litz wire to minimize power loss and thermal energy generation in which high frequency current flows, may lose an insulating performance of insulation coating and restrict operation temperature. So it is necessary in the first place to uniformly cool an entire surface of the work coil31.

Now, referring toFIG. 4illustrating an electric cooker1where a plurality of heat generating units30are disposed, the electric cooker comprises: an external case10having an air inlet11and an air outlet12; a cooking plate20mounted on an upper surface of the external case10; a plurality of heat generating units mounted at a bottom surface of a cooking plate20; and a cooling unit40connected to each heat generating unit30and for introducing outside air into the air inlet11to cool each heat generating unit30and to be discharged via the air outlet12.

The cooling unit40includes a blowing fan41horizontally disposed on an upper surface of the air inlet11for inducing the outside air in the vertical direction of the external case10, and a plurality of air ducts42vertically provided at the external case10for guiding the air sucked by the blowing fan41to be uniformly circulated to the bottom surface of each heat generating unit30.

The cooling unit40further includes a plurality of connecting ducts44disposed underneath each heat generating unit30for connecting each air duct4250that the outside air can be supplied. The outside air introduced via the blowing fan41and the air ducts42in this configuration passes each heat generating unit30via the connecting ducts44. Consequently, according to the present invention, each heat generating unit30can be effectively cooled in an electric cooker formed with the plurality of heat generating units30.

As apparent from the foregoing, the electric cooker according to the present invention has an advantage in that an optimum cooling efficiency can be embodied by a circulation structure where air sucked from outside can be directly transmitted to a heat generating unit.

Another advantage is that an effective heat radiation can be possible by a relatively small capacity of blowing fan to thereby enable to save the manufacturing cost. Still another advantage is that an effective utilization of space for parts arrangement can be enhanced by using a relatively small capacity of blowing fan, thereby enabling to manufacture an electric cooker in a thin, light, simple and compact manner. Still further advantage is that enhancement of radiation effect enables an electric cooker to be manufactured with a long durability and life.

The foregoing description of a preferred embodiment of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Any examples described or illustrated herein are intended as non-limiting examples, and many modifications or variations of the examples, or of the preferred embodiment(s), are possible in light of the above teachings, without departing from the spirit and scope of the present invention. The embodiment(s) was chosen and described in order to illustrate the principles of the invention and its practical application to thereby enable one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to particular uses contemplated. It is intended to cover in the appended claims all such changes and modifications that are within the scope of this invention.