AU2003246042B2 - Electric Heating Plate - Google Patents

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

Applicant(s): WIK FAR EAST LTD Actual Inventor(s): Dov Glucksman Address for Service: PATENT ATTORNEY SERVICES 26 Ellingworth Parade Box Hill Victoria 3128 Australia Title: ELECTRIC HEATING PLATE Associated Provisional Applications: No(s).: The following statement is a full description of this invention, including the best method of performing it known to me/us:- Electric Heating Plate The invention relates to an electric heating plate that provides two different cooking surfaces.

Cooking appliances with heating plates of the kind generally have different surfaces for accommodating different cooking styles. For example, flat cooking surfaces are used for griddling; ribbed cooking surfaces, for grilling. In home applications constraints on storage areas, utilization factors and costs often preclude a family from purchasing an individual cooking appliance to provide each type of cooking surface; such as one pan or cooking appliance with a flat surface for griddling and another pan or cooking appliance with a ribbed surface for grilling.

A number of efforts have been made to develop pans and cooking appliances that incorporate two cooking surfaces. Initially multiple cooking surface were incorporated in cooking pans that were adapted to be placed on an independent cooking surface, such as a stove. United States Letters Patent No.

1,733,450 (1929) to Detwiler for a cooking utensil and United States Letters Patent No. 2,198,646 (1940) to Walcott for a cooking utensil described two examples. Detwiler discloses a reversible cooking utensil in which one side is adapted to be used as a griddle and the other side is grooved to for use as a broiler or grill. Walcott discloses a similar structure that has a parallel ribbed surface for broiling and a flat surface for frying or griddling.

More recently efforts have been made to provide multiple cooking surfaces in self-contained cooking appliances. For example, United States Letters Patent No. 3,348,470 (1967) to Swanson discloses a waffle maker with an upper and lower housing. Each of the upper and lower housings contains a heating element that is closely juxtaposed a removable and reversible cooking plate or grid that has a griddle surface on one side and a waffle surface on the other side.

United States Letters Patent No. 3,632, 982 (1972) to Linger discloses a surface cooktop that has first and second positions. In a first position a cooking element is disposed in a recess of a stove counter or the like so that it is flush with the surface. For cooking the unit is removed and reversed to expose a flat cooking surface elevated above the counter. In reversing the structure electrical contacts are enabled to connect into electrical power.

United States Letters Patent No. 4,011,431 (1976) to Levin discloses an electric cooker with an electric heating element and base interposed by an invertible grill. The opposite faces of this grill present a circular dam for hamburgers or the like and a rectangular dam for sandwiches. A peripheral heating element in the cover provides heating.

United States Letters Patent No. 2,840,684 (1958) to Watkins discloses a cooking appliance in the form of a combination frying pan and griddle. This cooking appliance includes a heating element embedded in a peripheral wall of heat conducting material. A relatively thin heating plate spans the peripheral wall and includes a ribbed cooking surface on one side and a flat cooking surface on the other side. It is integrally formed with the peripheral side wall. In a first position the appliance provides a griddle surface; in a second, inverted position, a grilling surface. Even heating in this structure is attributed to using the combination of the thin heating element and the more massive peripheral wall with its embedded heater.

Placing a heater in the peripheral wall of heat conducting material assumes that the external surface of the heating pan becomes very hot. In Watkins legs space the cooking surface above a countertop to prevent heat radiating from the cooking surface from damaging the countertop. After use the cooking appliance apparently must be stored in some horizontal orientation as for cooking. The orientation is not conducive to placing other items on top of the cooking appliance. Consequently Watkins' cooking appliance will consume a significant storage volume. In addition the cooking appliance incorporates an integral thermostatic control. In a dishwasher environment, it is likely that water will penetrate any covers and corrode or otherwise destroy the electrical connections leading to premature failure. Thus, the cooking appliance is not dishwasher safe and must be washed by hand.

The above references to and descriptions of prior proposals or products are not intended to be, and are not to be construed as, statements or admissions of common general knowledge in the art in Australia.

It is an object of the invention to provide an electric heating plate with two different cooking surfaces, which is improved in respect of the prior heating element in particular in respect of easy cleaning and/or uniform heat distribution throughout the cooking surfaces and/or rapid heat distribution, and/or provides a useful alternative to the prior electric heating plates.

In accordance with a first aspect of this invention an electric heating plate with first and second cooking surfaces on opposites sides thereof and with an integral electric heating element arranged between said first and second cooking surfaces wherein said heating plate is cast about the heating element, and said heating plate has a smooth cooking surface and a ribbed cooking surface and wherein said heating element is embedded in said heating plate and said heating element includes first and second heating element parallel legs that extend through said heating plate and said heating element legs being embedded in one of said rib portions of said heating plate.

In accordance with another aspect of this invention an electric heating plate with first and second cooking surfaces on opposites sides thereof and with an integral electric heating element arranged between said first and second cooking surfaces wherein said heating plate is cast about the heating element, and wherein said heating element includes electrical connections extending from the first end of said heating plate and additionally comprising seals at the portions at which each of said electrical connections emerges from said heating plate at said first end thereof.

The invention is described in the following in conjunction with the accompanying dryings, in which like reference numerals refer to like parts, and in which: FIG. 1 is a perspective view of a cooking appliance constructed in accordance with this invention oriented for providing a smooth cooking surface; FIG. 2 is a perspective view of the cooking appliance in FIG. I reversed to provide a ribbed grilling surface; FIG. 3 is a perspective exploded view that depicts the components of the cooking appliance shown in the orientation of FIG. 2; FIG. 4 is a plan view of the cooking appliance in a vertically stored position; FIG. 5 is a perspective view partially cut away to depict certain aspects of this invention; FIG. 6 is detailed plan view that depicts the heating element used in the 4 cooking appliance of FIGS. 1 through FIG. 7 is a cross-section view through line 7-7 of FIG. 2; and FIG. 8 is a view of a thermostatic control used in connection with the cooking appliance of FIGS. 1 through FIGS. 1 through 3 depict a reversible self-contained electric cooking appliance 10 comprising a heating plate 11 according to one embodiment of this invention suspended between a first end stand 12 and a second end stand 13. A reflector pan 14 is suspended from the first and second end stands 12 and 13. A detachable thermostatic control 15 includes a power cord 16 and end cap 17 for connection to a conventional home power service.

The heating plate 11 in this particular embodiment is formed with a smooth cooking surface 20 shown in FIG. 1 and a ribbed cooking surface 21 shown in FIGS. 2 and 3. Thus in the orientation of FIG. 1 the cooking appliance is positioned for griddling; in the position shown in FIG. 2, for grilling.

The end stand 12 has a centre portion 22 and two diverging legs 23 and 24 that extend outwardly and divergently from the centre section 22. Likewise the second end stand 13 includes a centre section 25 with diverging legs 26 and 27.

The central sections 22 and 25 engage extensions on the heating plate 11 to suspend the heating plate 11 therebetween. Each of the end stands 12 and 13 typically will be molded from an insulating plastic that is strong and that will withstand a dishwasher environment. A variety of moldable plastics are available.

Such a material assures that the end stands 12 and 13 can be gripped during use without risk of burning an individual's hands.

With this configuration and as shown in FIG. 1, the legs 24 and 27 lie on a horizontal support surface 30 to position the smooth surface 20 for cooking.

Conversely when the cooking device 10 is positioned with the legs 23 and 26 on the horizontal support surface 30 a grilling surface 21 is presented for use. Thus, the end stands 12 and 13 suspend the reflector pan 14 intermediate the heating plate 11 and the horizontal support 30 in either orientation.

Now looking at FIGS. 1 through 3, the legs 26 and 27 terminate in spaced, parallel outer edges 31 and 32 respectively. These two spaced parallel edges 31 and 32 define a plane transverse to a median plane through the heating element 11 parallel to the horizontal support 30 in the orientation shown in FIGS. 1 through 3.

Now referring to FIG. 4, the edges 31 and 32 provide a stable support platform or foot that enables the cooking appliance 10 to be stored in a vertical orientation on a shelf or other horizontal support. The divergence of the legs 26 and 27 from the median plane assures that the centre of gravity of the cooking appliance lies intermediate the edges 31 and 32 so the cooking appliance 10 is stable in this vertical storage position. As will now be apparent, this vertical storage capability greatly reduces the storage requirements of the cooking appliance 10 by minimizing shelf area. In one specific embodiment, the horizontal shelf space occupied by the cooking appliance 10 is less than 20% of the shelf space that l0 would be occupied with the cooking appliance 10 in a horizontal orientation such as shown in FIG. 1.

As will also now be apparent the cooking appliance 10 has a reversible feature due to the construction of the ends stands 12 and 13 and the suspension of the heating plate 11 between the end stands 12 and 13. Like the end stand 13, the end stand 12 includes the legs 23 and 24 that terminate at edges 33 and 34 of edge surfaces 35 and 36, respectively. The surfaces 35 and 36 are parallel to the midplane. The end stand 13 includes a similar set of parallel surfaces with parallel surface 37 adjacent the edge 31 and parallel surface 38 adjacent the edge 32. The edges 35, 36, 37 and 38 constitute feet for supporting the cooking appliance 10 in one of the two cooking orientations. As shown in FIG. 1, the feet 36 and 38 support the cooking appliance 10; in FIG. 2, the feet 35 and 37 provide the support.

Thus, the cooking appliance 10 shown in FIGS. 1 and 2 includes a heating plate 11 with first and second cooking surfaces 20 and 21 on opposite sides. The first and second end stands 12 and 13 connect to opposite ends of the heating plate and suspend the heating plate 11 parallel to and spaced from a supporting surface, such as a supporting surface 30. The pan 14 mounts intermediate the heating plate and the support surface.

More specifically the reflector pan 14, as shown in FIG. 3 includes metal bottom 40 that may be flat or stamped in various forms for stiffening and a peripheral side wall 41. Tongues 42 and 43 extend from the peripheral side wall 41 at opposite ends of the reflector pan 14. These tongues slide into oppositely located grooves formed in the end stands 12 and 13. More specifically, the end stand 12 includes two parallel spaced grooves 44 and 45 located on opposite sides of the midplane in the central section 22. Similar slots 46 and 47 are formed in the centre section 25 of the end stand 15. An optional handle 50 can be attached to the front edge of the pan 14 particularly to the corners of the peripheral wall 41 to 6 facilitate the removal of the pan from the cooking appliance In the orientation of FIG. 1 the slots 45 and 47 support the reflector tongues 42 and 43. In the orientation shown in FIG. 2 the slots 44 and 46 receive the tongues 42 and 43.

The pan 14 performs two functions. First, if the pan 14 is formed of a reflective material, it will impede any radiant heat transfer to the support 30. That is, it will tend to reflect any radiant heat back to the heating element 11. This enables the heating element 11 to be located closer to the support surface 30 while minimizing any risk of damaging the support surface 30, such as a laminated countertop. Further closer spacing reduces the overall height of the cooking appliance 10 in the orientation shown in FIGS. 1 and 2 and further minimizes the storage requirements when the cooking appliance 10 is stored as shown in FIG. 4 because it will require even less shelf space.

Still referring to FIG. 3, the bottom portion 40 and a peripheral wall 41 constitute a receptacle for accumulating grease or other materials that drain fi'om a cooking surface during use. FIGS. 5 and 7 particularly depict a drain formed by a plurality of slots 51 through the heating plate 11. These drain slots 51 are preferably located at one end of the heating plate 11 adjacent one of the end stands 12 or 13 and formed during casting of the heating plate 11. In this particular embodiment the drain slots 51 are located at the end proximate the end stand 13 to locate the drain remotely from the end stand 12 which includes the thermostatic control 15 and power connections. Each of the slots 51 passes through the heating plate between adjacent ribbed surfaces. With this structure grease can be moved toward the second end stand 13 to drain through the various drain slots 51 and be accumulated in the reflector pan 14.

To facilitate draining, the end stands 12 and 13 can also be constructed with a vertical span between the edges 33 and 34 of the end stand 12 that is slightly greater than the corresponding vertical span between the edges 31 and 32.

When the cooking appliance 10 rests on a horizontal support surface 30 the differential will elevate the end of the heating plate proximate the end stand 12 thereby providing natural drainage of grease or other materials by gravity toward the drain slots 51 by tilting the cooking surface slightly.

The heating plate 11 is formed of aluminum or other heat conducting material that is cast about an electrical heating element 52 shown particularly in FIGS. 5 and 6. As shown particularly in FIG. 6, the heating element 52 includes 7 two spaced, parallel legs 53 and 54. Each of the legs includes a wound heating ribbon or wire 55 encased in an outer sheath 56. An intermediate section or leg 57 extends between corresponding ends of the legs 53 and 54. It also includes a portion of the wound ribbon or wire 55 thereby to provide electrical continuity between the legs 53 and 54. At the other end, an electrical connector 60 attaches to a conductor 61 that in turn connects to one end of the wound wire 55. A connector 62 similarly connects to a conductor 63 from the other end of the wound wire In manufacture the entire structure is initially formed as linear structure with a maximum pitch across the length of the heating element corresponding to the intermediate leg 57. In the portions corresponding to the legs 53 and 54, the pitch is selected to produce an appropriate heat output per unit length. As a result the output per unit length across the intermediate leg 57 is significantly less than the corresponding output for unit length from the parallel legs 53 and 54. After forming this structure, it can be bent into the form shown in FIG. 6. Such manufacturing processes are well known in the art.

Now referring to FIGS. 3 and 5, during the molding process the embedded heating element 52 is positioned so the connectors 60 and 62 emerge at the edge of the heating plate 11 proximate the first end stand 12. Bushings 64 and associated with the connectors 60 and 62 assure a positive seal against any water or other materials entering the casting.

As shown most clearly in FIG. 3, the end stand 13 has a socket 66 to receive a portion of an extension 67 of the heating plate 11. Similarly a socket 68 on the end stand 12 is adapted to be engaged and surround an extension through which connectors 60 and 62 extend. The extension 67 as particularly shown in FIGS. 3 and 5, has embedded therein the intermediate leg 57 of the heater element 52. To minimize heat transfer to the end stand 13, that can also be used as a handle, spacers 71 provide a standoff distance such that the socket 66 overlies only a portion of the extension 67. Thus air is free to move through the resulting air gap and maintain a minimal heat transfer to the end stand 13.

FIG. 7 depicts a cross-section through the heating plate 11 with its smooth surface 20 on the bottom and ribbed surface 21 on the top. FIG. 7 also depicts the location of the drain slots 51 between adjacent ones of the ribs. In accordance with one aspect of this invention, the heating element leg 53 is embedded in a portion of the heating plate 11 that forms a rib 72 of the cooking surface 21; and the heating element leg 54, in a rib 73. Locating the heating element legs 53 and 54 in 8 interior portions of the heating element within the perimeter defined by the cooking surfaces 20 and 21 provides more even heating than would otherwise would be available by providing a heating element about the periphery of the heating plate 11. Placing the intermediate leg 57 with its reduced heat output outside the cooking surfaces further minimizes heating unevenness that would be found if the intermediate leg 57 were located within the perimeter of the cooking surfaces 20 and 21.

Thus the heating plate 11 by virtue of being cast about the heating element 52 as described provides substantially uniform heating over the cooking surface or 21. Moreover, the combination of casting and sealing the heating plate 11 and the selection of appropriate materials for the end stands 12 and 13 provides a structure that is dishwasher safe. Consequently, it is possible to place the cooking appliance 10 in a dishwasher after the thermostatic control 15 is removed.

FIGS. 3 and 8 depict the detachable thermostatic control 15. FIG. 3 also depicts a supporting structure of the end stand 12 that includes a central socket 74 surrounding the male connectors 60 and 62. The heating plate 11 also includes a well 75 formed in the casting in a position corresponding to a central rib. The thermostatic control 15 comprises a body 76 that carries female power sockets and 81 that align with the male connectors 60 and 62. A centrally located temperature probe 82 fits in the well 75. All these project from the end 83 of the thermostatic control 15. In viewing the thermostatic control 15 from the end 83, the structure is symmetrical so the thermostatic control can always be placed in the heating plate 11 in either cooking orientation with the control knob 84 in an upper, readily visible position.

The knob 84 controls the operation of a conventional thermostatic control on/off switch 85 through a rotary shaft 86. Such on/off thermostatic control switches are well known in the art. In addition the housing 81 carries a lamp 87 proximate a reference or index position 88 on the housing. This lamp 87 back lights a portion or sector at the index position 88 so that the back lighting illuminates that portion of any translucent lettering 89 that is at the index position 88.

When the structures of FIG. 3 are assembled into the cooking appliance of FIGS. 1 and 2, the cooking appliance 10 is characterised by having first and second cooking surfaces on opposite sides of a cast metal heating plate 11 with an embedded heating element 52 that is suspended between first and second end stands 12, 13 of an insulating material. The ends stands 12, 13 are symmetrical to 9 allow the heating plate 11 to be supported substantially parallel to a support surface 30 in either a first or second orientation that makes one of the first or second cooking surfaces available for use. Diverging legs on one end stand enable the cooking appliance to be placed in a horizontal position for cooking and in a vertical orientation for storage. A reflector mounts between the end structures 12 and 13 thereby to reflect heat from the heating plate 11 and minimize the transfer of heat to the supporting surface 30. This reflector additionally may be formed to accumulate grease or other cooking materials if a drain, such as the drain formed by the slots 51, is formed through the heating plate 11. Properly selecting materials for the end stands, sealing all the electrical connectors and using a detachable thermostatic control allows the cooking appliance to be cleaned in a dishwasher without fear of destroying any of the electrical components.

This specific embodiment depicts particular structures, such as the cooking surface 21, with particular characteristics, such as a parallel, spaced rib surface.

Other cooking surfaces could be substituted for one or both of the specifically disclosed cooking surfaces, although certain configurations, such as a waffle surface, might prevent inhibit or prevent grease from draining from such a cooking surface. One specific electric heating plate has been disclosed with a specific arrangement of components. Other heating plates could be substituted.

Differently shaped end structures could be substituted for the specifically disclosed end stands 12 and 13.

Claims (12)

1. Electric heating plate with first and second cooking surfaces on opposites sides thereof and with an integral electric heating element arranged between said first and second cooking surfaces wherein said heating plate is cast about the heating element, said heating plate has a smooth cooking surface and a ribbed cooking surface, and wherein said heating element is embedded in said heating plate, and said heating element includes first and second heating element parallel legs that extend through said heating plate, and said heating element legs being embedded in one of said rib portions of said heating plate.

2. Electric heating plate with first and second cooking surfaces on opposites sides thereof and with an integral electric heating element arranged between said first and second cooking surfaces wherein said heating plate is cast about the heating element, and wherein said heating element includes electrical connections extending from a first end of said heating plate and additionally including seals at the portions at which each of said electrical connections emerges from said heat- ing plate at said first end thereof.

3. Electric heating plate as claimed in claim 1 wherein said heating element includes electrical connections extending from the first end of said heating plate and additionally including seals at the portions at which each of said electrical connections emerges from said heating plate element at said first end thereof.

4. Electric heating plate as claimed in any one of claims I through 3 further including a drain with at least one opening through said heating plate intermediate at least one of the ribs forming the ribbed cooking surface.

Electric heating plate as claimed in any one of claims 1 through 4 having at least one drain through said heating plate.

6. Electric heating plate as claimed in any one of claims 1 through 5 wherein said heating element further includes an interconnecting element extending be- tween first ends of said first and second legs and being embedded in a portion of said heating plate extending beyond said cooking surfaces.

7. Electric heating plate as claimed in any of claims 1 through 6, wherein said heating element includes a wound heater having a first pitch over the length of first and second legs and a second pitch over the length of said interconnecting element.

8. Electric heating plate as claimed in any one of claims 1 through 7 wherein said first and second legs and said interconnecting element of the heater element include a wound heating ribbon or wire encased in an outer sheath.

9. Electric heating plate as claimed in any one of claims 1 through 8 wherein said heating plate with its integral electric heating element is suspended on oppo- site sides by first and second end stands suspending said heating plate therebe- tween substantial parallel to and spaced from a support surface.

Electric heating plate as claimed in claim 9 wherein one of the end stands includes a support that carries the interconnecting element arranged outside the cooking surfaces of the heating plate with an air gap there about.

11. Electric heating plate as claimed in any one of claims 1 through 10 addi- tionally including a thermostatic control detachable from said heating plate in- cluding a control knob, an index formed on said control, said control knob in- cluding translucent portions for identifying predetermined operating conditions for said thermostatic control and a light for 5acklighting said translucent portions proximate said index.

12. Electric heating plate as claimed in any one of claims 1 through 11 and substantially as hereinbefore described with reference to the accompanying drawings. Dated this 9th day of September 2003 PATENT ATTORNEY SERVICES Attorneys for WIK FAR EAST LTD