INDUCTION HOB

Abstract

An induction hob comprising a plurality of induction coils (12, 14, 16, 18); drive circuitry (22, 24) for powering the induction coils; a user interface (26) connected with the drive circuitry; and a housing which supports the induction coils, the drive circuitry and the user interface; and characterized in that the housing comprises a bottom part (10) made of molded plastic comprising mounting means for the mounting of the induction coils (14, 16, 18, 20), the drive circuitry (22, 24) and the user interface (26).

Claims

1. An induction hob comprising: a plurality of induction coils; drive circuitry for powering the induction coils; a user interface connected with the drive circuitry; and a housing which supports the induction coils, the drive circuitry and the user interface; the housing comprising a bottom part made of molded plastic comprising mounting means for the mounting of the induction coils, the drive circuitry and the user interface.

2. The induction hob of claim 1, comprising at least one fan for conveying air through the housing.

3. The induction hob of claim 2, wherein the housing comprises at least one integrally formed air guide for directing air through the housing.

4. The induction hob of claim 3, wherein the housing comprises one or more air guides that divide the housing into a plurality of separate housing compartments.

5. The induction hob of claim 4, wherein the one or more air guides comprise wall elements that span a height of an interior of the housing.

6. The induction hob of claim 2, wherein the housing comprises cooling channels that convey air to components of the drive circuitry that require cooling.

7. The induction hob of claim 2, wherein the drive circuitry comprises at least one printed circuit board having electronic components mounted thereon, wherein the printed circuit board is mounted in the housing so as to be exposed to an air stream generated by the at least one fan.

8. The induction hob of claim 1, wherein components of the drive circuitry that require intensive cooling are mounted in a cut-out of the printed circuit board at a bottom side of a cooling body.

9. The induction hob of claim 8, wherein components of the drive circuitry that require intensive cooling are mounted on the printed circuit board so as to be aligned to an air stream that is conveyed across the printed circuit board.

10. The induction hob of claim 1, wherein the housing comprises a plurality of reinforcing ribs.

11. The induction hob of claim 1, wherein the mounting means comprises at least one snap-fit joint for mounting the induction coils, the drive circuitry, the user interface and/or a further element of the induction hob.

12. The induction hob of claim 11, wherein the at least one snap-fit joint comprises at least one of a hook, a knob, a protrusion, a bulge, or a bracket and a cooperating depression, undercut, detent, opening, edge or rim.

13. The induction hob of claim 1, wherein the drive circuitry comprises one or two power boards, each said power board comprising one or two power generators, each said power generator being associated to one induction coil.

14. The induction hob of claim 1, wherein the drive circuitry comprises at least one quasi-resonant inverter.

15. The induction hob of claim 1, wherein the drive circuitry comprises a resonant half-bridge inverter.

16. The induction hob of claim 1, wherein the drive circuitry comprises at least one switching element which is an Insulated Gate Bipolar Transistor.

17. The induction hob of claim 1, wherein the housing comprises a top part having at least one glass-ceramic panel that covers at least one of the induction coils.

18. The induction hob of claim 17, wherein the top part comprises a single glass-ceramic panel that covers all the induction coils.

19. The induction hob of claim 18, wherein the user interface comprises an array of touch sensitive elements that are arranged below the single glass-ceramic panel.

20. An induction hob comprising: a housing comprising a molded plastic bottom part comprising integrally formed first, second, third and fourth snap-in connections, and a glass-ceramic panel disposed above the molded plastic bottom part, a first induction coil mounted to said plastic bottom part via said first snap-in connection, a printed circuit board having driving circuitry configured to drive said induction coil mounted to said plastic bottom part via said second snap-in connection, a second induction coil mounted to said plastic bottom part via said third snap-in connection, and a user interface connected with the driving circuitry and mounted to said plastic bottom part via said fourth snap-in connection, at least one air guide provide as one or a plurality of vertical walls integrally formed with said molded plastic bottom part and extending therefrom up to an underside surface of said glass-ceramic panel to thereby define and at least partially isolate from one another first and second compartments of said housing, said first induction coil and said printed circuit board being disposed in the first compartment and said second induction coil being disposed in the second compartment, said fan being configured to direct a flow of cooling air within said first compartment over electronic components of said printed circuit board and thereafter into said second compartment, a plurality of first reinforcing ribs being formed integrally and arranged in a crossing-pattern array in a bottom wall of said plastic bottom part, and a plurality of second reinforcing ribs being formed integrally with said plastic bottom part and extending between the bottom wall thereof and at least one of a vertical wall or a side wall thereof, said user interface comprising an array of touch sensitive elements arranged below the glass-ceramic panel and actuable by a user touching an upper surface of the glass ceramic panel, said induction hob omitting separate fasteners for securing any of the first or second induction coils, the printed circuit board or the user interface to the housing, said housing possessing no metal at its exterior surface and thus omitting any earth connection configured to electrically ground the housing.

Description

[0021] The present invention is described in further detail below by reference to the drawings in which

[0022] FIG. 1 illustrates a first embodiment of an induction hob in accordance with the present invention; and

[0023] FIG. 2 illustrates a second embodiment of an induction hob in accordance with the present invention.

[0024] The induction hob illustrated in FIG. 1 comprises a housing that consists of a bottom part 10 in which there are mounted the various components of the hob and which is covered by a top part 12 which in the illustrated embodiment comprises a single glass-ceramic panel. Note that while the glass-ceramic panel comprises a tinted glass so as to block the view into the interior of the housing, for illustrative purposes top part 12 is shown in FIG. 1 as a transparent member.

[0025] Bottom part 10 is an element that is made of molded plastic in which there are integrally formed various mounting means for mounting component of the induction hob. In particular, the bottom part 10 supports four induction coils 14, 16, 18 and 20, a first and a second printed circuit board 22 and 24 with drive circuitry for powering the induction coils, a user interface 26 connected with the drive circuitry for control of the induction coils 14, 16, 18 and 20, and two fans 28 and 30 for generating cooling air streams that are conveyed through the housing.

[0026] To provide for structural stability, bottom part 10 comprises plural integrally formed reinforcing ribs, some of which are configured as an array 32 of crossing ribs that form a grid along surface areas of bottom part 10. Further reinforcing ribs 34 and 36 are provided along edge regions of bottom part 10 so as to extend between the bottom wall 38 and a side wall 40 and a back wall 42, respectively.

[0027] The housing is divided into several housing compartments by a number of air guides, which are configured as vertical wall elements 44 that span the height of the interior of the housing between bottom wall 38 and the glass ceramic panel 12. In this manner air can be conveyed from air inlets that are located below the fans, along the components of the hob to air exits which are provided in a wall section of the housing, such as in the embodiment shown in FIG. 1 an exit that is provided at the rear side in the region where the reinforcing ribs 36 are located.

[0028] In the embodiment shown in FIG. 1, the air guides divide the housing into a first housing compartment in which there is located fan 28 and induction coil 18 and from which cooling air also is passed to user interface 20 to be vented via an air exit that is located below user interface 20, a second housing compartment in which there is located fan 30 and induction coil 20, a third housing compartment in which there is located induction coil 16 and the second printed circuit board 24 and a fourth housing compartment in which there is located induction coil 14 and first printed circuit board 22.

[0029] As is illustrated in FIG. 1, depending on the temperature tolerances of the components to be cooled and their location within the housing, there can be a fan that is dedicated to just a single housing compartment, as in the illustrated embodiment applies for fan 28 which only is assigned to the first housing compartment with induction coil 18. Further there can be provided a fan that is configured to convey cooling air to more than one housing compartment, as in the illustrated embodiment applies for fan 26 which provides cooling air for the second housing compartment with induction coil 20, from which the air stream passes on into the third housing compartment with induction coil 16. Finally, there also can be provided one or more housing compartments that are cooled by convective cooling without assistance of a fan, as in the shown embodiment applies for the fourth housing compartment with induction coil 14.

[0030] In the embodiment illustrated in FIG. 2 the induction hob comprises one larger induction coil 46 and two smaller induction coils 48 and 50 which all are mounted in a common plastic housing 51. A first printed circuit board 52 comprises drive circuitry for powering the larger induction coil 46 and a second printed circuit board 54 comprises drive circuitry for powering the two smaller induction coils 48 and 50.

[0031] In both cases the drive circuitry that also is supported by housing comprises a power generator having a single Insulated Gate Bipolar Transistor (IGBT) which is arranged in a quasi-resonant configuration. In a preferred embodiment that is designed for operation at a voltage of 220 to 240 V and a frequency of 50 or 60 Hz, each power generator is designed to generate a power of up to 2.2 kW. As is illustrated in FIG. 2, whereas most of the components 56 that constitute the drive circuitry are mounted on the upper side of the printed circuit boards 52 and 54, the IGBTs which during use are heated to a considerable extent and which thus require intensive cooling, are mounted in cut-outs of the printed circuit boards 52 and 54 at the bottom side of respective cooling bodies which in FIG. 2 are illustrated as elements 58, 60 and 62.

[0032] In order to supply cooling air to the cooling body 58 mounted on the first printed circuit board 52, there is provided a first fan 64 which conveys air via a cooling channel 66 to the cooling body 58. Despite fan 64, due to spatial constraints, being located remote from the first printed circuit board 52, by the aid of cooling channel 66 first fan 64 is able to provide sufficient cooling air to the first printed circuit board 52 and in particular to the cooling body 58 of the IGBT that drives induction coil 46.

[0033] Second printed circuit board 54 is cooled by a second fan 68 which in the embodiment illustrated in FIG. 2 is located in direct proximity to the second printed circuit board 54. Considering that most of the cooling is required for cooling the IGBTs for switching induction coils 48 and 50, second fan 68 is configured to direct air to cooling body 62, at the bottom side of which there is mounted the IGBT for induction coil 50. Note that cooling body 60 at the bottom side of which there is mounted the IGBT for induction coil 48 is located in alignment with second fan 68 and cooling body 62, so that the air stream that is generated by the second fan 68 after having passed over cooling body 62 flows over cooling body 60.

[0034] Similarly as in the embodiment illustrated in FIG. 1, a user interface 70 is provided in a front part of the housing 51. User interface 70 is connected with the printed circuit boards 52 and 54 and comprises various input and display elements for control of the induction coils 46, 48 and 50.

[0035] By the provision of a plastic housing that supports all the main hob components, such as the induction coils, the fans, the power electronics, and the user interface, several advantages are achieved over conventional induction hobs.

[0036] Thus, the manufacturing of the hob can be substantially facilitated because the various mounting means for fixing the components of the hob can be configured as integral parts of the housing, wherein such mounting means further can be designed as snap-in connections that do not rely on any separate fixing members such as screws and the like.

[0037] Furthermore, as the plastic housing allows to design the hob to have no metal parts on the outer part of the hob, an earth connection as it is required in conventional hobs can be omitted, which not only further facilitates assembly and complexity of the hob, but which also results in a reduced emission of electromagnetic noise and, as a consequence, in reduced costs for the EMC filter circuit which usually is provided in electric devices such as induction hobs.

[0038] In the induction hob suggested herein, the reinforcing ribs and the air guides that provide for the multi-function of providing for stability to the housing, dividing the housing into several separate heat sink compartments, and guiding the cooling air from the fans to any components to be cooled, result in a robust design of the plastic housing that avoids bending of the housing despite the fact that due to the provision of a plurality of induction coils the housing inherently has a relatively large surface area.

REFERENCE SIGNS

[0039] 10 bottom part (plastic housing part) [0040] 12 top part (glass-ceramic panel) [0041] 14 induction coil [0042] 16 induction coil [0043] 18 induction coil [0044] 20 induction coil [0045] 22 first printed circuit board [0046] 24 second printed circuit board [0047] 26 user interface [0048] 28 fan [0049] 30 fan [0050] 32 array of reinforcing ribs [0051] 34 reinforcing ribs [0052] 36 reinforcing ribs [0053] 38 bottom wall [0054] 40 side wall [0055] 42 rear wall [0056] 44 air guide [0057] 46 induction coil [0058] 48 induction coil [0059] 50 induction coil [0060] 51 housing [0061] 52 first printed circuit board [0062] 54 second printed circuit board [0063] 56 PCB components [0064] 58 cooling body [0065] 60 cooling body [0066] 62 cooling body [0067] 64 first fan [0068] 66 cooling channel [0069] 68 second fan [0070] 70 user interface