AU3826002A

AU3826002A - Electric cook top assembly

Info

Publication number: AU3826002A
Application number: AU38260/02A
Authority: AU
Inventors: Russell Kimmins
Original assignee: COSMOS SOLAR Pty Ltd
Current assignee: COSMOS SOLAR Pty Ltd
Priority date: 2001-02-27
Filing date: 2002-05-09
Publication date: 2002-06-27
Anticipated expiration: 2021-02-27
Also published as: AU744216B3; AU761137B2

Description

Regulation 3.2

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT

APPLICANT:

Invention Title: COSMOS SOLAR PTY LTD ELECTRIC COOK TOP ASSEMBLY The following statement is a full description of this invention, including the best method of performing it known to me: ELECTRIC COOK TOP ASSEMBLY Field of the Invention The present invention relates to an electric cook top assembly and has particular application to electric barbecues.

Background There are at present approximately thirty five thousand 240V electric barbecues, incorporating cook top assemblies rated mostly at 7.2kW, installed as public facilities in parks and recreational reserves throughout Australia. If used for minutes 15 times per week each barbecue's average power consumption would be 45kW hrs per week. At present the cost associated for a Shire or Council to run twenty such barbecues is approximately $5,600 per annum.

Apart from the cost involved in running the type of barbecue known in the prior art there is also the disadvantage of the volume of green house gas emissions associated with the electricity generation required to power the barbecues.

A further problem is that the hard insulative coating surrounding the active heating element of the prior art cook top assemblies may cause potentially lethal welding of the live element to the barbecue cook plate. This problem is particularly prevalent in areas where it is difficult to make a good electrical earth connection, such as sandy beach areas.

It is an object of the present invention to provide a cook top assembly which is suitable for incorporation into a barbecue and which addresses the problems of cook top assemblies known in the prior art as described above.

Summary of the Invention According to a first aspect of the present invention there is provided a cook top assembly including: a metal cooking plate; an uninsulated electrical heating element operable at extra low voltage toheat the cooking plate; electrically insulative material positioned between and in substantial abutment with the cooking plate and the heating element to electrically insulate the cooking plate therefrom; and a first thermal insulative material positioned to prevent heat loss away from the underside of the cooking plate and the heating element.

As used herein the expression "uninsulated electrical heating element" refers to a heating element which is not substantially encased or surrounded by an electrically insulative material. To illustrate this in relation to domestic appliances for example, the heating element in an electrical hot water system is an insulated electrical heating element, whereas the heating elements in toasters, bar radiators and hair-dryers are uninsulated electrical heating elements.

As used herein the expression "extra low voltage" refers to voltages not exceeding 40 volts.

Preferably the cook top assembly includes clamping means arranged to force the heating element towards the cooking plate.

Preferably the low voltage heating element is of a type formed from a nickel and chrome alloy.

Preferably the low voltage heating element is comprised of about Nickel and about 20% Chrome.

Preferably a first force distribution member is positioned to distribute compressive forces over the first thermal insulative layer.

In a preferred embodiment at least a second thermal insulative layer is present located away from the first thermal insulative layer and adjacent the force distribution member.

A second force distribution member may be located between the first and second thermal insulative layers.

It is preferred that the cook top assembly include means to force the cooking plate and the heating element towards each other.

The cook top assembly may be arranged to force the cooking plate and the heating element towards each other by clamping the force distribution member towards the cooking plate.

The first force distribution member may be a cover or simply a plate.

Preferably the cooking plate is clamped towards the force distribution member by means of a fixing member extending from the cooking plate and protruding through the first force distribution member for engagement by an engagement means in a compressed state.

The fixing member may be a tube with a threaded end in which case the engagement means is most conveniently a complementary nut.

The cooking plate may include a drain hole with the tube in communication therewith.

According to a further aspect of the invention there is provided a barbecue comprising a cook top assembly mounting in combination with a cook top assembly of the type described previously.

A convenient power supply for a cook top assembly of the type discussed above is a solar power supply which may be supplied in combination with the cook top assembly or with the barbecue mounting and cook top assembly previously referred to.

Alternatively the cook top assembly may be supplied in combination with a switch mode power supply for powering of the cook top assembly from a relatively high power mains supply such as a 240V AC supply.

In another aspect the invention resides broadly in a method of assembling a cook top assembly, the method including:positioning a sheet of electrically insulative material between and in substantial abutment with a metal cooking plate and an uninsulated electrical heating element operable at extra low voltage, the cooking plate being heated by the heating element and electrically insulated therefrom; positioning a first thermal insulative material beneath the heating element to prevent heat loss away from the underside of the cooking plate and the heating element, and forcing the heating element toward the underside of the cooking plate.. It is preferred that the low voltage heating element is forced toward the underside of the cooking plate by biasing towards the cooking plate a force distributing member positioned beneath the insulative material.

Brief Description of the Figures In order that this invention may be readily understood and put into practical effect, reference will be made to the accompanying drawings wherein: Figure 1 is a perspective view of an electric barbecue incorporating a cook top assembly according to an embodiment of the present invention.

Figure 2 is an exploded view of an electric cook top assembly according to an embodiment of the present invention.

Figure 3 is a cross section through the cook top assembly of Figure 2.

Detailed Description of Preferred Embodiments With reference to Figure 1, there is depicted an electric barbecue 2 including an electric cook top assembly 4, power supply batteries 8, power regulator 10 and on/off switch 11. In the embodiment shown the barbecue is powered by batteries 8 which are recharged by a solar panel, not shown. As will be explained, the cook top assembly of the present invention is a low-power type and in the present embodiment is designed to be powered by a 24V power supply. Consequently there is no need for a power inverter as would be the case if prior art 240V cooktop assemblies were used.

The construction of cook top assembly 4 will be explained with reference to Figure 2. Figure 2 is an exploded underside view of the cook top assembly. Cook top assembly 4 includes stainless steel cooking plate 12 from the centre of which protrudes threaded tube 15 which is in communication with drain 7. Positioned adjacent the underside of cooking plate 12 is an electrically insulative material in the form of a 2mm thick sheet of mica paper 16 available under the trade name "Phologomite". Mica paper 16 serves to electrically insulate plate 12 from heating element 18. The heating element is an 80% Nickel, 20% Chrome 2.91mm dia noninsulated wire of 3.06m length. The operating voltage is 24Volts DC drawing approximately 50A thereby operating at.1200 Watts. The element terminates at either end with connectors 20 and 21.

Heating element 18 is backed with a first thermal insulative layer in the form of a 25mm thick insulative blanket 22 of spun alumina-silica fibres. This type of insulating material is known commercially under the name of "Fiberfrax". A blanket formed of such fibres is available commercially under the trade name "Durablanket Fiberfrax". Blanket layer 22 serves to heat insulate heating element 18 so that heat is not lost away from cooking plate 12. Beneath heating element 18 there is located a force distribution member in the form of mill-board 23 which is made of compressed Fiberfrax. Mill-board 23 serves to distribute force uniformly across blanket layer 22 once cook top assembly 4 is assembled as will be discussed later.

Beneath the mill-board there is located a second thermal insulative blanket layer 26 and finally a galvanised steel cover 28 which also operates as a further force distribution layer member.

With reference to Figure 3, which is view of a cross-section of the cook top assembled, threaded tube 15 is located through corresponding holes in each of the components 16, 22, 24, 26, 28. The terminals 24 and 20 are similarly passed through corresponding holes in layers 24-28 so that they protrude through cover 28.

Washer 30 is passed over the protruding tube 15 which acts as a .fixing member extending from the cooking plate. The assembly is then compressed by tightening bolt 32, which acts as an engagement means, on the threaded end of tube 15. Compression serves to force element 18, mica sheet 16 and cooking plate 12 into hard contact with each other thereby increasing the efficiency of heat transfer from element 18 to plate 12. In particular element 18 is forced towards the underside of the cooking plate 12.

It will be apparent to those skilled in the art that other arrangements for clamping the cover towards the cooking plate may are possible.

A cook top assembly of the type described may be provided in combination with a solar panel power supply using a 24V DC nominal standard solar regulator.

Alternatively the cook top assembly may be run from mains power. In that event it is recommended that an efficient switch mode power supply be used to convert the 240V mains power to 24V rather than a transformer with its associated losses.

The inventor has found that a barbecue incorporating a cook-top assembly of the type described above will use approximately 80% less energy than the conventional types presently available. Accordingly the cost to a Shire Council, for example, of running twenty barbecues incorporating an electric cook top of assembly of the type described would be about $930 per annum in contrast to the $5,600 for running the same number of conventional electric barbecues. Of course the cost of purchasing electricity will be zero if solar power is used.

It will be realised that while the cook top assembly has been described in the context of barbecues it may also be incorporated into other cooking appliances such as frying pans or stove tops for mobile homes.

It will also be realised that the above has been given only by way of illustrative example of the invention and that all such modifications and variations thereto, as would be apparent to persons skilled in the art, are deemed to fall within the broad scope and ambit of the invention as is described herein.

Claims

1. A cook top assembly including: a metal cooking plate; an uninsulated electrical heating element operable at extra low voltage to heat the cooking plate; electrically insulative material positioned between and in substantial abutment with the cooking plate and the heating element to electrically insulate the cooking plate therefrom; and a first thermal insulative material positioned to prevent heat loss away from the underside of the cooking plate and the heating element.

2. A cook top assembly as claimed in claim 1, and including clamping means to force the heating element towards the cooking plate.

3. A cook top assembly as claimed in claim 1, the assembly being included in a barbecue.

4. A cook top assembly as claimed in claim 1,wherein the low voltage heating element is formed from a nickel and chrome alloy.

A cook top assembly as claimed in claim 4, wherein the low voltage heating element is comprised of substantially 80% Nickel and 20% Chrome.

6. A cook top assembly as claimed in claim 1, wherein a first force distribution member is positioned to distribute compressive forces over the first thermal insulative layer.

7. A cook top assembly as claimed in claim 1, wherein at least a second thermal insulative layer is located away from the first thermal insulative layer and adjacent the force distribution member.

8. A cook top assembly as claimed in claim 7, wherein a second force distribution member is located between the first and second thermal insulative layers.

9. A cook top assembly as claimed in claim 1, and including biasing means to force the cooking plate and the heating element towards each other.

A cook top assembly as claimed in claim 9, wherein the biasing means includes clamping means for clamping the force distribution member towards the cooking plate.

11. A cook top assembly as claimed in claim 10, wherein the clamping means is a fixing member extending from the cooking plate and protruding through the first force distribution member for engagement by an engagement means in a compressed state.

12. A cook top assembly as claimed in claim 11, wherein the fixing member is a tube with a threaded end and the engagement means is a complementary nut.

13. A cook top assembly as claimed in claim 12, wherein the tube constitutes a drain for draining the cooking plate.

14. A method of assembling a cook top assembly, the method including:- positioning a sheet of electrically insulative material between and in substantial abutment with a metal cooking plate and an uninsulated electrical heating element operable at extra low voltage, the cooking plate being heated by the heating element and electrically insulated therefrom; positioning a first thermal insulative material beneath the heating element to prevent heat loss away from the underside of the cooking plate and the heating element, and 9 forcing the heating element toward the underside of the cooking plate. A method of assembling a cook top assembly as claimed in claim 14, wherein the low voltage heating element is forced toward the underside of the cooking plate by biasing towards the cooking plate a force distributing member positioned beneath the insulative material.