EP0809078B1 - Cooking apparatus with forced-draft burner - Google Patents

Cooking apparatus with forced-draft burner Download PDF

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Publication number
EP0809078B1
EP0809078B1 EP97103503A EP97103503A EP0809078B1 EP 0809078 B1 EP0809078 B1 EP 0809078B1 EP 97103503 A EP97103503 A EP 97103503A EP 97103503 A EP97103503 A EP 97103503A EP 0809078 B1 EP0809078 B1 EP 0809078B1
Authority
EP
European Patent Office
Prior art keywords
combustion chamber
gas
main
thermostat
cooking
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP97103503A
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0809078A2 (en
EP0809078A3 (en
Inventor
Mauro Moro
Luca Codazzi
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Electrolux Professional SpA
Original Assignee
Electrolux Professional SpA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Electrolux Professional SpA filed Critical Electrolux Professional SpA
Publication of EP0809078A2 publication Critical patent/EP0809078A2/en
Publication of EP0809078A3 publication Critical patent/EP0809078A3/en
Application granted granted Critical
Publication of EP0809078B1 publication Critical patent/EP0809078B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • 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
    • F24C3/00—Stoves or ranges for gaseous fuels
    • F24C3/12—Arrangement or mounting of control or safety devices
    • F24C3/126—Arrangement or mounting of control or safety devices on ranges
    • F24C3/128—Arrangement or mounting of control or safety devices on ranges in baking ovens
    • 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
    • F24C3/00—Stoves or ranges for gaseous fuels
    • F24C3/08—Arrangement or mounting of burners
    • F24C3/085—Arrangement or mounting of burners on ranges
    • F24C3/087—Arrangement or mounting of burners on ranges in baking ovens
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N5/00—Systems for controlling combustion
    • F23N5/18—Systems for controlling combustion using detectors sensitive to rate of flow of air or fuel
    • F23N2005/181—Systems for controlling combustion using detectors sensitive to rate of flow of air or fuel using detectors sensitive to rate of flow of air
    • F23N2005/182—Air flow switch
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N2223/00—Signal processing; Details thereof
    • F23N2223/22—Timing network
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N2227/00—Ignition or checking
    • F23N2227/04—Prepurge
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N2233/00—Ventilators
    • F23N2233/06—Ventilators at the air intake
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N2235/00—Valves, nozzles or pumps
    • F23N2235/02—Air or combustion gas valves or dampers
    • F23N2235/06—Air or combustion gas valves or dampers at the air intake
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N2235/00—Valves, nozzles or pumps
    • F23N2235/12—Fuel valves
    • F23N2235/14—Fuel valves electromagnetically operated
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N5/00—Systems for controlling combustion
    • F23N5/02—Systems for controlling combustion using devices responsive to thermal changes or to thermal expansion of a medium
    • F23N5/12—Systems for controlling combustion using devices responsive to thermal changes or to thermal expansion of a medium using ionisation-sensitive elements, i.e. flame rods
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N5/00—Systems for controlling combustion
    • F23N5/20—Systems for controlling combustion with a time programme acting through electrical means, e.g. using time-delay relays

Definitions

  • the present invention refers to an apparatus for cooking food, adapted to perform cooking by means of a flow of flue gases which, generated by a plurality of heating elements, is forced by one or more fans to circulate in one or more heat exchangers arranged in a heat-exchanging relation with the cooking cavity in which the food to be cooked is arranged.
  • Apparatuses are known in the art, in which the burner, or the element provided to diffuse the flue gas in the air, is enclosed in a chamber forming the actual combustion chamber, into which a flow of air is forced which is taken in from the outside and blown against said burner by a normal fan.
  • the US-A-4 240 397 discloses a gas-fuelled oven with a thermostatically controlled gas supply valve which supplies fuel to the gas burner at cycled intervals.
  • the US-A-5 197 665 discloses a water heater whereby a blower is maintained in operation for a preset time to exhaust substantially all combustion gases.
  • the main advantage of such apparatuses lies in the fact that a much greater heat output is generated and transferred here with respect to equally sized burners and heat exchangers not provided with said forced-draft feature.
  • so blown air is used not only as both primary air and secondary air for combustion purposes, but also as "purging" air for the cavity in which the burner is housed, all such terms being well-known to all those who are skilled in the art, so that they shall not be explained any further here.
  • Such a ventilation period is intended to "purge”, ie to remove any possible presence of fuel gas that may be stagnating there due to possible leakages through the plug of the gas valve, in view of avoiding explosion risks.
  • the purging time shall be selected so as to ensure that the total volume of fresh air circulated in the period turns out to amount to at least five times the volume of the combustion chamber increased by the volume of the heat exchanger and the flue outlet conduit.
  • FIGS 1, 2 and 3 are shown to illustrate a food cooking oven of the fan-assisted or forced-convection type used in professional kitchens, comprising a cooking cavity 1, a combustion chamber 2 provided with a gas burner 3, a heat exchanger 4 that doubles as a flue conduit for exhausting the products of combustion, the flame 5 generated by the burner also penetrating said heat exchanger arrangement.
  • the oven is also provided with a blower means 14 adapted to take in an air flow from the outside ambient and blow the same flow into said combustion chamber 2.
  • All electric circuits of the oven are furthermore connected to the power supply line through a main on-off switch 13, as this is shown in Figure 3.
  • the oven Upon starting a cooking operation, the oven is of course cold, or anyway at a lower temperature than actually needed, so that setting the thermostat to the desired cooking temperature value causes said thermostat to close and, therefore, the burner to be ignited by energizing the igniter 7.
  • Ignition is further prevented from taking place by the fact that, even if the thermostat 21 is closed, the same thermostat is however connected to the power supply line only through a delaying means 16, preferably a time-delay relay 16 which is in turn energized by a pressure switch 17 arranged on the mouth of the blower and actuated by the air flow brought about by such a blower.
  • a delaying means 16 preferably a time-delay relay 16 which is in turn energized by a pressure switch 17 arranged on the mouth of the blower and actuated by the air flow brought about by such a blower.
  • the related triggering terminals 19 and 20 are closed only after a pre-determined period of time, during which the combustion chamber is purged, and their being closed causes a particular circuit 20 of the control unit 10 to be connected to the power supply line, so that it will be able to immediately operate the igniter 7 for the ignition of the burner. It will therefore be fully appreciated that such an igniter is by all means and positively operated only after such a delay time is elapsed and the combustion chamber has therefore been purged.
  • the thermostat 21 Upon reaching the pre-set cooking temperature, the thermostat 21 opens, but this has actually no effect on the time-delay relay 16, which therefore stays closed since it is being energized by the main on-off switch 13 on the one hand and, on the other hand, by the pressure switch 17 that is actuated by the still operating blower 14.
  • the purging of the combustion chamber is simply and fully obtained also under blower-off conditions, ie. with de-energized blower (see Figure 2), by the simple natural ventilating action of the atmospheric air flowing through said combustion chamber by passing through the heat exchanger 4 on the one side and, on the other side, through at least an adequately sized opening 26 that is provided in an appropriate position on one side of the combustion chamber.
  • said opening 26 For a correct, balanced operation of the oven it is of course necessary for said opening 26 to be sufficiently large so as to enable the combustion chamber to be correctly ventilated by said natural air flow within a pre-determined time.
  • the same opening 26 shall however not be too large, ie. so large as to become a possible way through which the air blown into the combustion chamber, which must be mainly used as primary air and secondary air for the combustion of the gas, can leak.
  • the aim is in this manner reached of ensuring that, when the burner is off, the combustion chamber is anyway ventilated permanently and, as a result, purged by a modest, but sufficient natural flow of atmospheric air that enables the burner to be ignited immediately, so that the need no longer arises for a special preliminary phase of forced ventilation and purging of said combustion chamber to be provided before igniting the burner.

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Control Of Combustion (AREA)
  • General Preparation And Processing Of Foods (AREA)
  • Regulation And Control Of Combustion (AREA)
EP97103503A 1996-05-22 1997-03-04 Cooking apparatus with forced-draft burner Expired - Lifetime EP0809078B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
IT96PN000031A IT1289379B1 (it) 1996-05-22 1996-05-22 Apparecchiatura di cottura con bruciatore ad aerazione forzata
ITPN960031 1996-05-22

Publications (3)

Publication Number Publication Date
EP0809078A2 EP0809078A2 (en) 1997-11-26
EP0809078A3 EP0809078A3 (en) 2000-03-08
EP0809078B1 true EP0809078B1 (en) 2002-07-17

Family

ID=11395145

Family Applications (1)

Application Number Title Priority Date Filing Date
EP97103503A Expired - Lifetime EP0809078B1 (en) 1996-05-22 1997-03-04 Cooking apparatus with forced-draft burner

Country Status (5)

Country Link
EP (1) EP0809078B1 (it)
DE (1) DE69713956T2 (it)
DK (1) DK0809078T3 (it)
ES (1) ES2180834T3 (it)
IT (1) IT1289379B1 (it)

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2351146B (en) * 1999-06-19 2001-07-25 Stoves Group Plc Cooking appliances
FR2899956B1 (fr) * 2006-04-14 2008-07-25 Thirode Grandes Cuisines Poligny Bruleur a gaz pour four de cuisine
ITTO20130331A1 (it) * 2013-04-23 2014-10-24 Indesit Co Spa Forno a gas ad alto rendimento e metodo per il suo funzionamento
ITUB20159610A1 (it) * 2015-12-21 2017-06-21 Satengineering Sas Di Francesco Dursi & C Forno di cottura
US20200305642A1 (en) * 2019-03-29 2020-10-01 Lifetime Products, Inc. Fluid optimization mechanisms for cooking devices
IT202100002357A1 (it) 2021-02-03 2022-08-03 Ali Group S R L “dispositivo antirisonanza in un forno a gas del tipo per la cottura degli alimenti nella ristorazione collettiva”

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4240397A (en) * 1979-01-24 1980-12-23 Raytheon Company Fuel saver oven
IT1220754B (it) * 1988-06-01 1990-06-21 Zanussi Grandi Impianti Spa Forno di cottura a gas a convezione forzata
US5197665A (en) * 1990-11-29 1993-03-30 Rheem Canada Ltd. Water heater
IT235007Y1 (it) * 1994-01-17 2000-03-31 Zanussi Grandi Impianti Spa Forno di cottura con generatore di vapore a bruciatore soffiato

Also Published As

Publication number Publication date
ES2180834T3 (es) 2003-02-16
EP0809078A2 (en) 1997-11-26
DE69713956D1 (de) 2002-08-22
DE69713956T2 (de) 2002-11-07
IT1289379B1 (it) 1998-10-02
ITPN960031A0 (it) 1996-05-22
ITPN960031A1 (it) 1997-11-22
EP0809078A3 (en) 2000-03-08
DK0809078T3 (da) 2002-11-04

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