Classifications

• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B3/00—Ohmic-resistance heating
  • H05B3/68—Heating arrangements specially adapted for cooking plates or analogous hot-plates
  • H05B3/74—Non-metallic plates, e.g. vitroceramic, ceramic or glassceramic hobs, also including power or control circuits
  • H05B3/746—Protection, e.g. overheat cutoff, hot plate indicator
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F24—HEATING; RANGES; VENTILATING
  • F24C—DOMESTIC STOVES OR RANGES ; DETAILS OF DOMESTIC STOVES OR RANGES, OF GENERAL APPLICATION
  • F24C15/00—Details
  • F24C15/10—Tops, e.g. hot plates; Rings
  • F24C15/102—Tops, e.g. hot plates; Rings electrically heated

Definitions

• the present invention relates to hobs of the type which employ radiant heating elements.
• ceramic hobs using radiant heating elements, such as tungsten halogen lamps, or inductive heating units.
• radiant heating elements such as tungsten halogen lamps, or inductive heating units.
• ceramic hobs also give the advantage of being easy to clean and are aesthetically pleasing, normally comprising four or more heating units mounted under a single sheet of glass-ceramic.
• a hob comprising: a substantially
• planar member having at least one aperture therein defining a hotplate region; a substantially planar glass-ceramic insert located in the aperture and a radiant heating element below the glass-ceramic insert, the glass-ceramic insert being moulded.
• the present invention retains the advantages provided by a conventional ceramic hob
• the phrase "moulded glass-ceramic insert” includes inserts made by moulding glass which is then heat treated to change the structure of the glass to that of a glass-ceramic.
• One such material would be lithium-alumino-silicate.
• this lens is a Fresnel lens enabling the lowermost surface of the
• the insert is moulded to support a temperature sensitive element, substantially the whole of the temperature sensitive region of the element preferably being held in thermal contact of the insert. This enables the heating element to then be controlled in dependence on the temperature glass-ceramic
• temperature sensitive element is preferably formed by a region of the glass-ceramic
• the glass-ceramic material of the insert is a poor electrical conductor, the resistance of which is temperature dependent.
• the electrodes would normally be closely spaced because of the poor resistive nature of the glass-ceramic, but this ensures the resistive value is not significantly altered
• the region of the insert forming the temperature sensitive region can have material
• the electrodes, or conductive strip of the above embodiments are preferably deposited by screen printing, pad printing or by a spray deposition method.
• control means is electrically connected to the temperature sensitive
• seal between the insert and the member which seal is formed from a mixture of alumina/glass fibre and a silicone sealant.
• a mixture prevents the ingress of water or dirt below the insert, and also provides a high resistance to abrasion when the surface is cleaned.
• the member supports resilient mounting means which urge a canister in which the heating element is supported towards the insert, the canister comprising thermally insulating material which is arranged such that this is urged into contact with the insert.
• the member comprises a
• the glass-ceramic is thermo-chromic as this provides a visual indication that the glass-ceramic is hot even though the hob may be turned off.
• thermo-chromic glass- ceramic material for use in ceramic hobs.
• Figure 1 is a schematic view of part of a hob in accordance with the present invention
• Figure 2 is a cross-section along the line I-I of Figure 1 ;
• Figures 3 and 4 are alternative configurations of a hob in accordance with the present invention.
• Figure 5 is a perspective view of a hob of which figures 1 and 2 or 3 of 4 depict a part.
• the hob comprises a member 1 of vitreous enamelled
• the glass-ceramic inse ⁇ comprises a lithium-alumino-silicate which has a working range in which it can be moulded of 1200-1800°C.
• Insert 4 has a Fresnel lens 6 moulded onto its lower surface, seen in Figure 2, which controls the dispersion of light from tungsten halogen lamp 7, and on its upper surface spillage retention channel 10. Energisation of the lamp 7 is controlled in dependence on the electrical resistance of the lower surface of insert 4 which is determined by control circuitry (not shown) by measuring the resistive value of the glass between conductors 8a and 8b. These are platinum based electrodes formed by pad printing and
• the conductors 8a and 8b are
• canister 12 is lined with thermally insulating material 14, a wall portion 15 of which is
• FIG. 3 shows an alternative arrangement of the hob of Figure 1. In this arrangement
• the ceramic-glass insert 4 has three downwardly extending legs 16, only one of which
• Figure 4 illustrates an arrangement when the ceramic insert can be inserted into the member 1 from the top, with the canister 12 already in position. A downwardly
• Figure 5 illustrates a complete hob which Figures 1 and 2 or Figure 3 or Figure 4, depict
• This hob comprises five hotplates, but it will be realized that any number
• hotplates could be employed in a hob in accordance with the invention.

Landscapes

• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Ceramic Engineering (AREA)
• Resistance Heating (AREA)
• Electric Stoves And Ranges (AREA)
• Polishing Bodies And Polishing Tools (AREA)
• Confectionery (AREA)
• Extrusion Moulding Of Plastics Or The Like (AREA)
• Diaphragms For Electromechanical Transducers (AREA)
• Table Equipment (AREA)
• Baking, Grill, Roasting (AREA)

Applications Claiming Priority (3)

Publications (2)

Family

ID=10733734

Family Applications (1)

Country Status (8)

Families Citing this family (6)

Family Cites Families (10)

• 1993
  • 1993-04-13 GB GB9307608A patent/GB2277145B/en not_active Revoked
• 1994
  • 1994-04-07 DE DE69410791T patent/DE69410791T2/de not_active Expired - Fee Related
  • 1994-04-07 AT AT94912025T patent/ATE166955T1/de not_active IP Right Cessation
  • 1994-04-07 ES ES94912025T patent/ES2117787T3/es not_active Expired - Lifetime
  • 1994-04-07 JP JP6522872A patent/JPH08509057A/ja active Pending
  • 1994-04-07 EP EP94912025A patent/EP0694149B1/de not_active Expired - Lifetime
  • 1994-04-07 WO PCT/GB1994/000739 patent/WO1994024490A1/en not_active Ceased
  • 1994-04-07 AU AU64342/94A patent/AU6434294A/en not_active Abandoned

Non-Patent Citations (1)

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