GB2282058A

GB2282058A - Ventilation of induction heating jar

Info

Publication number: GB2282058A
Application number: GB9418336A
Authority: GB
Inventors: Kwan Jin Jung
Original assignee: Gold Star Co Ltd
Current assignee: LG Electronics Inc
Priority date: 1993-09-17
Filing date: 1994-09-12
Publication date: 1995-03-29
Anticipated expiration: 2014-09-12
Also published as: CN1104751A; JPH07163453A; KR950007763A; GB2282058B; GB9418336D0

Abstract

A cooling air ventilation device for an induction heating jar is disclosed. The ventilation device prevents cooling air from reaching the control printed circuit board PCB (26), the display (19) and the controller (13), thus preventing problems due to impurities in the cooling air, such as dust and moisture, reaching them. The device comprises a duct (29) and an air flow guider (31) for guiding the outside air to the switching devices on PCB (6) to be cooled. The induction heating jar is typically used for boiling rice. <IMAGE>

Description

COOLING ATR VENTILATION DEVICE FOR INDUCTTON HEATING JAR BACKGROUND OF THE INVENTION Field of the Invention The present invention relates in general to cooling air ventilation devices for induction heating jars and, more particularly, to a structural improvement in such ventilation devices for prevention of introduction of dust and moisture in the cooling air into all the controller part, the control PCB (Printed Circuit Board) and the display, thus to prevent malfimction of the induction heating jars due to dust and moisture.

Description of the Prior Art Differently from general electric jars indirectly heating their inner kettles by their heat transfer heaters, typical induction heating jars use strong magnetic lines of force for boiling rice charged in the inner kettles. With use of the strong magnetic lines of force, the induction heating jars may generate high caloric power of at least 1300 W relatively higher than the caloric power of about 1000 W of the general electric jars. Such high caloric power generates high heat and this high heat makes the induction heating jars complete desired rice boiling for a short time, so that the induction heating jar intrinsically provides good taste of boiled rice.

Differently from the general electric jars that merely heat the bottom parts of the inner kettles, the induction heating jars uniformly heat all parts of their inner kettles, thus to cause a uniform convection current in the kettle and to uniformly boil the rice in the kettle regardless of positions of the rice in the kettle. That is, the rice at the top part in the kettle as well as the rice at the bottom part in the kettle is evenly boiled when boiling the rice using the induction heating jar. In this regard, the induction heating jars have been wide used in recent years.

With reference to Fig. 1, there is shown a typical induction heating jar.

In Fig. 1, the main body of the induction heating jar is designated by the numeral 1. Placed in the interior of the main body 1 is an inner kettle 11 made of specified metals. The inner kettle 11 generally has a double structure comprising an aluminum inside part and a stainless steel outside part. Placed about the exterior bottom section of the inner kettle 11 is an oven base 23 that is adapted for not only guiding the inner kettle 11 but also preventing the bottom of the inner kettle 11 from directly contacting with an induction coil 21 placed under the oven base 23. The center of the oven base 23 is holed so as to form a predetermined diameter hole 23a. Surrounding the outside bottom section of the oven base 23 is a working coil base assembly 4 that is adapted for fixing and supporting both the induction coil 21 and a ferrite 20.The induction coil 21 generates strong magnetic lines of force when it is applied with electric power. The ferrite 20 acts as a kind of reflection means for converging the magnetic lines of force generated by the induction coil 21 upwardly or in the direction toward the inner kettle 11.

In the same manner as described for the oven base 23, the center of the working coil base assembly 4 is holed so as to form a predetermined diameter hole 24a.

Penetrating and placed in the predetermined diameter holes 23a and 24a of both the oven base 23 and the base assembly 4 is a kettle sensor assembly 5 comprising a kettle temperature sensor and a kettle weight sensor, both sensors being not shown in Fig. 1.

The kettle sensor assembly 5 is provided with a predetermined size of shoulder Sb at its top section. The top end of the shoulder Sb of the assembly S comes into contact with the outer bottom of the kettle 11. Fitted over the center shaft of the kettle sensor assembly 5 is a spring Sa. The bottom of the kettle sensor assembly 5 is provided with a flange Sc that in turn is fixed to the bottom of the working coil base assembly S. A power PCB (Printed Circuit Board) 6 for supplying appropriate electric power to the induction coil 21 is placed under the working coil base assembly 4. In order to readily radiate the heat generated by switching devices 6a of the power PCB 6 during rice boiling, a heat sink of the fin type made of aluminum plate is provided on a side top surface of the power PCB 6.

Placed on the side bottom surface of the power PCB 6 is a fan 8 that is adapted for cooling the heat generated by the devices 6a placed on the top surface of the power PCB 6. An air intake part 27 for inlet of outside air into the main body 1 is fixed to the outer bottom of the main body 1 just below the fan 8 as shown in Fig. 2. The outside air is introduced into the main body 1 through the air intake part 27 by force of the fan 8 and cools the heat generating devices 6a on the power PCB 6. The air, after cooling the devices 6a, is exhausted to the atmosphere through air exhaust ports 28 formed on the rear wall of the main body 1.

The induction heating jar also includes both a control PCB 26 and a display 19 on a predetermined front top position inside the main body 1 as shown in Fig. 1. The control PCB 26 and the display 19 are adapted for controlling the function of the jar and for displaying thereon the function contents controlled by the control PCB 26 respectively.

Placed under the control PCB 26 is a controller part 13 that includes both a power transducer (not shown) and varieties of functional circuits (not shown). Here, power transducer is adapted for transduction of high voltage input power into low voltage power.

The top of the inner kettle 11 is covered with a lid 2 that is provided with an annular inner cover 14. The annular inner cover 14 is fixed to the inner surface of the lid 2 and provided with a thermal insulating disc 15 fixed to the inside edge of the inner cover 14.

Placed under the inner cover 14 is an annular oven packing 16 whose top comes into contact with the bottom surface of the inner cover 14 and whose bottom comes into contact with the outside edge of the top end of the inner kettle 11. The oven packing 16 is adapted for prevention of possible flowing of the boiled contents out of the kettle 11 during rice boiling. Placed under the thermal insulating disc 15 is a top heater assembly 17 used for generation of a predetermined level of heat. The outside edge of the top heater assembly 17 is coupled to the top of the oven packing 16. The top heater assembly 17 is holed at its center so as to form a predetermined diameter hole 17a.

Placed under the top heater assembly 17 is an oven cover 30 that covers the top of the inner kettle 11. The top surface of the outside edge of the oven cover 30 comes into contact with the bottom surface of the outside edge of the top heater assembly 17.

However, the bottom surface of the outside edge of the oven cover 30 comes into contact with the top surface of the top edge of the inner kettle 11. In the same manner as described for the top heater assembly 17, the oven cover 30 is holed at its center so as to form a predetermined diameter hole 30a. Penetrating and placed in the holes 17a and 30a formed in the centers of both the top heater assembly 17 and the oven cover 30 is a center packing assembly 18. The center packing assembly 18 includes a reversed conical hollow packing body 18a and a packing bar 1 8b slidably received in the hollow packing body 18a. The top of the packing bar 1 8b is a ring part while the bottom of the packing bar 1 8b is a predetermined diameter head part (not shown). The top ring part of the packing bar 18b is coupled to the center hole 17a of the top heater assembly 17 while the bottom head part of the packing bar 1 8b is slidably received in a hole (not shown) formed in the packing body 18a. Please noted that the center packing assembly 18 is adapted for expelling a part of both pressure and temperature inside of the kettle 11 to the atmosphere, thus to keep both a predetermined constant pressure and a predetermined constant temperature inside the kettle 11.

The lid 2 is pivotally coupled to the main body 1 by a hinge shaft 3. The lid 2 includes an upper case 12 that forms a surrounding pan of the lid 2 and supports the control PCB 26 and the like thereon and acts as a lid supporter. Surrounding the outer surface of the upper side wall of the inner kettle 11 is a cylindrical heat plate 9. This heat plate 9 guides the inner kettle 11 and is provided with a heater (not shown) for effective prevention of heat transferring from the inner kettle 11 to the outside of the kettle 11 during rice boiling or kettle temperature keeping. Placed under the cylindrical heat plate 9 is a side coil 24 that is a part of the induction coil 21 but placed over the induction coil 21. The bottom of the side coil 24 comes into contact with the top of the oven base 23.

As best seen in Fig. 2 showing the bottom of the typical induction heating jar, the bottom of the main body 1 of the jar is provided with the air intake part 27. This air intake part 27 is shaped into a predetermined diameter cap provided with a plurality of air intake holes formed on the side wall of the cap-shaped air intake part 27.

As shown in Fig. 3 showing the rear section of the main body 1 of the typical induction heating jar, the outside air, after being introduced into the main body 1 through the air intake part 27 by force of the fan 8 and cooling the heat generated by the devices 6a on the power PCB 6, is exhausted to the atmosphere through the air exhaust ports 28 formed on the rear wall of the main body 1. In the typical induction heating jar, the air intake part 27 along with an air exhaust ports 28 constitutes a cooling air ventilation device for the induction heating jar.

The operational effect of the typical cooling air ventilation device for the induction heating jar will be given hereinbelow with reference to the drawings.

When the induction coil 21 is applied with electric power under the condition that the inner kettle 11 is charged with predetermined amount of rice and water, the induction coil 21 achieves a continued resonance using an outside DC voltage. Hence, a resonance current flows in the induction coil 21 and forms a magnetic line of force about the induction coil 21. The magnetic line of force formed about the induction coil 21 causes an electromagnetic induction effect which in turn causes Joules heat to be generated in the inner kettle 11. At this time, the kettle sensor assembly S, which is placed in the predetermined diameter holes 23a and 24a of both the oven base 23 and the base assembly 4, senses the inside temperature of the kettle 11 so as to appropriately control the kettle inside temperature and to achieve intended good taste of rice.

During cooking with the above induction heating jar, the switching devices 6a placed on the power PCB 6 generate large amount of heat, which heat may give bad effects on the surrounding elements. In order to prevent the possible bad effect on the surrounding elements, the power PCB 6 is provided with the fan 8.

That is, the fan 8 is rotated during cooking with the induction heating jar, thus to cause the outside air to be introduced into the main body 1 by force. The introduced outside air is exhausted to the atmosphere through the air exhaust ports 28 along with the heat generated by the devices 6a of the power PCB 6.

However, the cooling air introduced into the interior of the main body 1 by force of the fan 8 includes impurities such as dust and moisture. The impurities introduced into the main body 1 along with the outside air are apt to stick on the controller part 13, thus to cause malfunction of the controller part 13 and to deteriorate the operational reliability of the induction heating jar.

When the impurities infiltrate into the display 19, the display 19 becomes dim and this troubles the users and causes deterioration of operational reliability of the induction heating jar.

SUMMARY OF THE INVENTION It is, therefore, an object of the present invention to provide a cooling air ventilation device for an induction heating jar in which the above problems can be overcome and which prevents the impurity-laden cooling air introduced into the main body by force of a fan from passing by both the control PCB and the controller part, thus to prevent both the control PCB and the controller part from being troubled due to the impurities, such as dust and moisture, in the air and to improve the operational reliability of the induction heating jar.

It is another object of the present invention to provide a ventilation device for an induction heating jar which protects the display from the impurity-laden cooling air, thus to prevent infiltration of the impurities, such as dust and moisture, in the air into the display and to prevent dimming of the display due to the impurities and to improve the operational reliability of the induction heating jar.

In order to accomplish the above objects, a cooling air ventilation device for an induction heating jar in accordance with an embodiment of the present invention comprises: a power PCB (printed circuit board) for supplying electric power to a working coil of the jar, the power PCB being placed under a working coil base assembly in a main body of the jar and having a plurality of switching devices thereon; a fan for generating air suction force for sucking outside air into the main body for cooling the switching devices, the fan being rotatably mounted on the bottom surface of the power PCB; an air intake part provided on the bottom of the main body below the fan; a duct for guiding the outside air to a predetermined direction in the interior of the air intake part, the duct being mounted on the inner bottom surface of the main body about the air intake part; and an air flow guider for preventing the outside air from flowing to a controller part, a control PCB and a display but guiding the outside air to the switching devices, the air flow guider being mounted on a bottom edge of the working coil base assembly.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: Fig. 1 is a sectional view showing a construction of an induction heating jar having a typical cooling air ventilation device; Fig. 2 is a partial bottom perspective view of the induction heating jar of Fig. 1, showing an air intake part of the typical ventilation device; Fig. 3 is a partial rear perspective view of the induction heating jar of Fig. 1, showing an air exhaust ports of the typical ventilation device; Fig. 4 is a sectional view showing a construction of an induction heating jar having a ventilation device in accordance with a preferred embodiment of the present invention; ; Fig. 5 is a bottom perspective view of the induction heating jar of Fig. 4 with a bottom cover removed from the bottom of a main body; and Fig. 6 is a perspective view of an air flow guider of the ventilation device in accordance with the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring first to Fig. 4, there is shown a constnlctjon of an induction heating jar having a cooling air ventilation device in accordance with a preferred embodiment of the present invention. From comparison of the construction of this induction heating jar of Fig. 4 with the construction of the typical induction heating jar of Fig. 1, it is apparent that most of the elements of this induction heating jar are common with those of the typical induction heating jar. Those elements common to both this induction heating jar and the typical induction heating jar will thus carry the same reference numerals and further explanation for the elements is not deemed necessary. Hereinbelow, the new cooling air ventilation device according to this invention will be described with reference to the drawings, Figs. 4 to 6.

The ventilation device of this invention includes an air flow guider 31 that is placed in the bottom section inside the main body 1. The guider 31 is adapted for prevention of introduction of the cooling to all the controller part 13, the control PCB 26 and the display 19. The air flow guider 31 is shaped as if it was resulted from diametrically cutting a cylinder having an opened top and a closed bottom into two sections as shown in Fig. 6. The air flow guider 31 includes a flat section 33 and a curved section 32 extending from the flat section 33 for guiding the cooling air only to the heat sink 7. The straight free edge of the flat section 33 is provided with slots 33a in order for prevention of possible interference caused when installing varieties of buses, which buses in turn are connected to a working coil base 22 of the working coil base assembly 4.Horizontally extending from a side edge of the flat section 33 of the guider 31 is an extension 34 provided with a screw hole 34a. The screw hole 34a is adapted for mounting the air flow guider 31 on the working coil base 22 using a set screw 36. When mounting the guider 31 on the working coil base 22, the guider 31 is arranged with respect to the working coil base 22 such that the screw hole 34a of the guider 31 is aligned with an associated screw hole formed in a mounting projection 4a provided at the side bottom of the working coil base 22, and screwed to the mounting projection 4a using the set screw 36. The inside portion of the flat section 33 is stepped so as to form a stepped portion 33b which prevents interference of the flat section 33 with other elements (not shown) when mounting the air flow guider 31 on the working coil base 22.

When turning on the induction heating jar having the above ventilation device in order to boil rice, the jar starts its rice boiling operation in the conventional manner and, at the same time, the fan 8 starts its rotation for cooling the heat generated by the switching devices 6a of the power PCB 6. As a result of rotation of the fan 8, there is generated air suction force in the interior of the main body 1. With the air suction force, the outside air including impurities such as dust and moisture is introduced into the main body 1 through the air intake part 27 under the guide of a duct 29. The duct 29 is mounted on the inner bottom surface of the main body 1 about the air intake part 27.

With the presence of the air flow guider 31 mounted on the mounting projection 4a of the working coil base 22, the air, after being introduced into the main body 1, is prevented from flowing to the section about the controller part 13, the control PCB 26 and the display 19 but partially guided to both the heat sink 7 and the switching devices 6a on the power PCB 6. Prior to exhaust to the atmosphere through the air exhaust ports 28, the air cools the devices 6a.

As described above, the cooling air ventilation device for induction heating jar in accordance with the present invention reliably prevents the impurity-laden cooling air introduced into the main body of the jar from flowing to all the controller part, the control PCB and the display but guides part of the cooling air to the devices to be cooled, thus to prevent troubles of all the controller part, the control PCB and the display caused by the impurities, such as dust and moisture, in the cooling air.

Although the preferred embodiments of the present iílventioll have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Claims

WHAT IS CLAIMED IS:

1. A cooling air ventilation device for an induction heating jar comprising: a power PCB (printed circuit board) for supplying electric power to a working coil of the jar, said power PCB being placed under a working coil base assembly in a main body of the jar and having a plurality of switching devices thereon; a fan for generating air suction force for sucking outside air into said main body for cooling said switching devices, said fan being rotatably mounted on the bottom surface of the power PCB; an air intake part provided on the bottom of said main body below said fan; a duct for guiding the outside air to a predetermined direction in the interior of said air intake part, said duct being mounted on the inner bottom surface of the main body about the air intake part; and an air flow guider for preventing the outside air from flowing to a controller part, a control PCB and a display but guiding the outside air to said switching devices, said air flow guider being mounted on a bottom edge of said working coil base assembly.

2. The cooling air ventilation device according to claim 1, wherein said air flow guider includes: an air guide section for preventing the outside air from flowing to said controller part, said control PCB and said display but guiding the outside air to said switching devices; and a flat section mounted on the bottom edge of said working coil base assembly for supporting said air guide section, said flat section having a straight free edge provided with both a plurality of slots and an extension.

3. The cooling air ventilation device according to claim 2, wherein said slots of the flat section of the air flow guider are adapted for prevention of interference of the air flow guider with buses connected to the working coil base assembly.

4. The cooling air ventilation device according to claim 2, wherein said extension of the flat section of the air flow guider is provided with a screw hole for mounting the air flow guider on a mounting projection of the bottom edge of the working coil base assembly using a set screw.

5. The cooling air ventilation device according to claim 2, wherein a stepped portion is provided on a corner between said air guide section and said flat section, said stepped portion being adapted for prevention of interference of said flat section with other elements of the jar.

6. A ventilation device substantially as hereinbefore described with reference to and as shown in Figures 4 to 6 of the accompanying drawings.