WO2005028961A1

WO2005028961A1 - Cooking method and apparatus

Info

Publication number: WO2005028961A1
Application number: PCT/GB2004/004065
Authority: WO
Inventors: Marcello Nocera
Original assignee: Marcello Nocera
Priority date: 2003-09-23
Filing date: 2004-09-23
Publication date: 2005-03-31
Also published as: EP1700065B1; EP1700065A1; WO2005028961A8

Abstract

A gas cooking apparatus comprises a hob (4) arranged to be supplied with gas for heating a cooking receptacle on the hob (4), a valve (14) via which the gas can be supplied to the hob (4), a mechanical detector (42) for detecting the presence of a cooking receptacle on the hob (4), and a mechanical transmission (28-34) operatively associated with the detector (42) and the valve (14) and whereby displacement of the receptacle onto the hob (4) results in opening of the valve (14) and removal of the receptacle from the hob (4) results in closing of the valve (14).

Description

COOKING METHOD AND APPARATUS This invention relates to a cooking method and apparatus . It is a common problem with cookers in use in busy environments, e.g. restaurants, that the user of the cooker will forget to turn off a gas hob when he removes for example a pan from the hob. This is a waste of resources and also a fire and safety hazard. According to a first aspect of the present invention, there is provided a cooking method, comprising displacing a cooking receptacle to a heating position, the displacement causing the receptacle mechanically to initiate increase of the supply of a gaseous fuel as a source of heat to heat said receptacle, and subsequently removing said receptacle from said heating position, the removal mechanically causing the supply of said fuel to be reduced. The increase and the reduction are preferably from and to nil supply. According to a second aspect of the present invention, there is provided cooking apparatus, comprising heating means arranged to be supplied with a gaseous fuel for heating a cooking receptacle at a heating position, valve means via which said fuel can be supplied to said heating means, mechanical detecting means for detecting the presence of a cooking receptacle at said heating position, and mechanical transmission means operatively associated with said detecting means and said valve means and whereby displacement of said receptacle into said heating position results in opening of said valve means and removal of said receptacle from said heating position results in closing of said valve means. The opening and the closing are preferably from and to a shut-off condition. Owing to the invention it is possible to detect automatically the removal of a cooking receptacle and reduce the supply of gaseous fuel to the heating position. In order that the invention may be clearly and completely disclosed, reference will now be made, by way of example, to the accompanying drawings, in which :- Figure 1 is a top plan view of a commercial gas cooker; Figure 2 is a diagrammatic, fragmentary, sectional, front elevation of the cooker; Figure 3 is a detail of Figure 2 to a larger scale; Figure 4 is a side view of a plunger assembly of one of six identical added, on/off-valve operating devices of the cooker; Figure 5 is an axial section through a boss of the plunger assembly; Figure 6 is a vertical section through a coupling of the plunger assembly; Figure 7 shows an exploded axial section through one of a plurality of identical burner/valve devices of a modified version of the cooker; Figure 8 shows an axial section through a device according to Figure 7, with the valve closed, and Figure 9 is a view similar to Figure 8, but with the valve open. Referring to the drawings , the commercial gas cooker 2 has an existing set of hobs 4 which are six in number (but can be higher or lower in number) . Each hob 4 has an existing gas pilot light (not shown) with its own existing on/off valve (not shown) and this pilot light remains lit throughout the time that the cooker is generally in use. The hobs include respective central burners 6 supplied with heating gas through respective pipings 8. Existing pipework has been modified, as indicated diagrarnirtatically by the dotted lines 8', to provide the pipings 8. Above each pair of burners 6 is an existing upwardly removable grid 10 which serves to support cooking receptacles at spacings above the burners 6. Below each pair of burners 6 is an existing upwardly removable tray 12. Below the trays 12 are added respective on/off valves 14 connected into the modified parts of the pipings 8, which latter extend below the trays 12 from existing gas supply control valves (not shown) at the front of the cooker 2 via the respective valves 14 to the respective existing burner inlets 16. Each valve 14 includes a lower housing part 18 with an inlet and an outlet connected to its associated piping 8, and an upper housing part 20 attached to the part 18 and including an upwardly extending sleeve 22 receiving therein a vertically reciprocable valve closure member 24 , with a sealing O-ring 26 between the sleeve 22 and the closure member 24. The closure member 24 projects from the top of the sleeve 22 and is downwardly displaceable, against the action of a return spring in the valve 14, by a vertically reciprocable plunger assembly 26. The assembly 26 includes, at its lower end, a tube 28 which can be caused to bear downwardly on the valve closure member 24 to open the on/off valve 14. The tube 28 is made of a ceramic material to minimise conduction of heat from the remainder of the plunger assembly to the valve closure member 24. The plunger assembly 26 also includes a coupling 30 of tubular form and having at its lower end a plain bore 32 into which is fixed, by- gluing, the upper end of the ceramic tube 28. The plunger assembly 26 also includes a threaded rod 34 which is screwed into internal threading 36 in the upper part of the coupling 30. At its upper end, the rod 34 carries a boss 38 and a lock nut 40 which retains the boss 38 against rotating relative to the rod 34. The boss 38 is of hexagonal external cross-section and is formed with a domed top surface 42. It includes, extending axially downwardly, an internally threaded stem 44 whereby the boss 38 can be screwed onto the rod 34. Once the boss 38 has been screwed onto the rod 34 so as to place the dome 42 at a desired level, the lock nut 40 is tightened to retain the boss 38 against further rotation relative to the rod 34. Each grid 10 includes a number of thin fingers 46 projecting radially inwards towards the corresponding burners 6, but at a level above that of the burners 6. The plunger assembly 26, and thus the valve 14 operated thereby, are arranged on a vertical axis which extends relatively close to one of the fingers 46 associated with the burner 6 which is supplied via the particular valve 14. The corresponding boss 38 is located at roughly the same level as the finger 46 but such that its domed surface 42 protrudes at a level just above the upper edge of the adjacent finger 46. Each plunger assembly 26 is guided in its vertical movement by a vertical tube 48 which, at its upper end, is substantially a sliding fit in an annular groove 50 formed in the boss 38 around the stem 44. At its lower end the tube 48 is fixed in a tank fitting 52 fixedly mounted in a hole provided therefor in the associated tray 12. The coupling 30 is substantially a sliding fit in the lower end of the tube 48. Below the three trays 12 is a tray 54 to which the valves 14 are fixed by way of respective brackets 56. The shaped head of the plunger assembly 26 provided by the dome 42 enables the receptacle to be slid over the hob or placed directly from above onto the hob, without damage to the plunger assembly or the receptacle. In use of the modified cooker, at the beginning of his work, the chef switches on the pilot lights. As he places a cooking receptacle on one of the hobs 4, the domed surface 42 at that hob detects the presence of the receptacle by mechanical pressure and opens the valve 14 dedicated to that particular hob, resulting in the pilot light lighting the supply of gas to the hob. By adjusting the gas supply control valve (not shown) m the piping 8 to the hob, the chef can adjust the rate of gas supply. When the receptacle is removed from the hob, the valve 14 is switched off by its return spring. In an alternative arrangement, the valve 14 allows a very low real level of supply while the receptacle is absent and is switched to a higher level when the domed surface 42 detects the presence of the receptacle. In a further alternative arrangement, the chef is able to preset the desired real level of supply to each hob from among a range of levels, so that, when he places the receptacle in its cooking position on the hob, the gas supply to the hob automatically commences at that preset level. The operation of the boss (38) may be translated into a movement that operates the valve (34) in any desired orientation. A linkage or other mechanical device may be used to transfer the movement. However, the arrangement shown is the simplest form, in having a single-sense movement only. Although the plunger is shown as not being integral with the burner, it could in fact be part of the burner itself. The valve 14 has been described as a separate component to the gas supply control valve (not shown) , but could be designed into it instead. In the device shown in Figures 7 to 9, it is a burner head which, by placing of a cooking receptacle thereon, is vertically downwardly displaced against the action of a spring to open an on-off valve. The device consists of two elements, namely the burner head 101 and a burner body assembly 120. The burner body assembly 120 consists of an injector 102, a lock nut 103, a sliding cover 104, flange fixing screws 105, a flanged upper body sleeve 106, a gas-tight diaphragm 107, a sealing plate 108, a sealing washer 109, a plunger 110, the helical compression spring 111 and a flanged lower body cup 112. In assembling the assembly 120, the plunger 110 is fitted with the sealing washer 109, the sealing plate 108 and the diaphragm 107. The lower end of the plunger is then inserted into the compression spring 111 and the whole placed into the cup 112 which includes a gas inlet stub 113. The sleeve 106 is located over the cup 112 and the plunger 110. The whole is clamped together using the flange fixing screws 105. The sliding cover 104 is placed over the plunger 110 and the diaphragm 107 and secured in position using the lock nut 103. The injector 102 is screwed into a bore 114 in the upper end of the plunger 110 to complete the burner body assembly 120. The burner assembly 120 is hard-piped into a gas supply and the burner head 101 is located over the injector 102, sitting on top of the sliding cover 104. The top edges of the receptacle-supporting fingers 46 and the tops of receptacle- supporting humps 115 on the burner head 101 are vertically spaced apart by a distance d in the condition shown in Figure 8 (in which the receptacle has not yet been placed upon the head 101) such that, upon placing of a receptacle on the humps 115 of the head 101, the head 101 is moved downwards by the receptacle through the distance d until the receptacle rests upon the fingers 46, to bring the device into the condition illustrated in Figure 9. With a gas supply valve/isolation cock (not shown) open, the system is charged. Gas G can flow into the cup 112 but cannot flow further because the compression spring 111 urges the plunger 110 to press the washer 109 sealingly against the face of the sealing edge of the plate 108, which thus provides an annular valve seat 116. When a cooking receptacle is placed on top of the burner head 101 the sliding cover 104, the plunger 110 and the attached parts move down through the pre-determined distance d, opening the valve 108,109 and thereby allowing gas G to flow into the diaphragm 107. The gas then flows through radial bores 117 and an axial bore 118 in the plunger 110 and through the injector 102 into the burner head 101 to mix with primary air A introduced via ports 119 in the underside of the head 101 and thence between the plunger 110 and the head 101 into the interior of the head 101 whence the gas/air mixture G/A leaves via outlet ports 121, before ignition by a pilot at the burner ports 121 as illustrated in Figure 9. The burner 101 operates until the receptacle is removed. The compression spring 111 then causes re-sealing of the valve seat 116 and thus cutting-off of the gas supply to the burner head 101. The present system is applicable also to other cooking apparatus such as ovens. It is also applicable to domestic gas appliances. The system can include a safety device that gives an aural warning that the hobs are ready to receive a cooking receptacle in order to avoid an accidental placing on the hobs of an object that is not desired to be heated. The warning does not sound until the last hob is not in use, i.e. if any of the hobs are in use then no warning sound is made. This warning does not sound if a safety lid of the cooker is closed. Various other modified versions are feasible. In one version, the continuous gas pilot light is replaced with an electronic device (a spark system or a hot surface ignitor) which lights the pilot shortly before the main burner upon each call for heat, i.e. upon the receptacle's being placed upon the hob. In another version, a pilot light is not provided; instead, upon each call for heat an electronic device (a spark system or a hot surface ignitor) lights the gas emitted by the burner. In a further possibility, any of the versions hereinbefore described could be supplemented with fan assistance where the air, the gas, or the gas and air mixture, is forced or induced into the burner or to the point of combustion by the use of one or more fans.

Alternatively, there could be fan-assisted pre-mix combustion (where the gas and the air are mixed and ignited prior to entering the main burner) with a mechanical valve arrangement similar to that shown diagramiτiatically for either version illustrated in the drawings. If desired, with fan-assisted pre-mix combustion there can be added a mechanism whereby the detection of a call for heat initiates a control sequence which operates the fan which then induces or forces an appropriate amount of gas to mix with the air and pass to the burner. With this system a gas/air ratio valve is used and a shut-off valve may not be necessary. Each of the unillustrated versions mentioned above may require a degree of electronic control, in which case microswitches (or similar) may need to be operated by the movement of the plunger.

Claims

1. A cooking method, comprising displacing a cooking receptacle to a heating position, the displacement causing the receptacle mechanically to initiate increase of the supply of a gaseous fuel (G) as a source of heat to heat said receptacle, and subsequently removing said receptacle from said heating position, the removal mechanically causing the supply of said fuel (G) to be reduced.

2. A method according to claim 1, wherein the increase and the reduction are from and to nil supply.

3. Apparatus according to claim 1 or 2, where said displacement of said cooking receptacle to said heating position causes said receptacle to move a burner (101) downwards until said receptacle comes to rest upon a stationary member (46), the downward movement of said burner (101) initiating said increase of said supply of said fuel (G) .

4. Cooking apparatus, comprising heating means (4) arranged to be supplied with a gaseous fuel (G) for heating a cooking receptacle at a heating position, valve means (14; 108, 109) via which said fuel (G) can be supplied to said heating means (4), mechanical detecting means (42; 115) for detecting the presence of a cooking receptacle at said heating position, and mechanical transmission means (28-34; 101, 110, 111) operatively associated with said detecting means (42;115) and said valve means (14; 108,109) and whereby displacement of said receptacle into said heating position results in opening of said valve means (14; 108, 109) and removal of said receptacle from said heating position results in closing of said valve means (14; 108, 109) .

5. Apparatus according to claim 4, wherein the opening and the closing of said valve means (14; 108, 109) are from and to a shut-off condition of said valve means (14;108,109) .

6. Apparatus according to claim 4 or 5, wherein said transmission means (28-34 ; 101, 110, 111) comprises a plunger (28-34;110) and biasing means (111), said plunger (28-34; 110) being depressible against the action of said biasing means (111) by said displacement of said receptacle into said heating position.

7. Apparatus according to any one of claims 4 to 6, wherein said transmission means (28-34) includes thermal insulation (28) constituting a barrier to conduction of heat from the upper end of said plunger (28-34) to said valve means (14).

8. Apparatus according to any one of claims 4 to 7, wherein said transmission means (28-34) is adjustable in length.

9. Apparatus according to any one of claims 4 to 8, wherein said transmission means (101,110,111) includes a vertically displaceable burner (101) .

10. Apparatus according to claim 9, wherein said valve means (108,109) is part of a valve (106-109,111,112) including an upper body sleeve (106) , a gas-tight diaphragm (107), and a lower body cup (112), said diaphragm (107) being interposed sealingly between said body sleeve (106) and said lower body cup (112) and being sealingly connected between said valve means (108,109) and said plunger (110).

11. Apparatus according to claim 10, wherein said plunger (110) is provided with ducting (117,118) whereby said fuel (G) can flow through said diaphragm (107).

12. Apparatus according to claim 10 or 11, wherein said plunger (110) carries a cover (104) slidingly fittingly mounted over said upper body sleeve (106) .

13. Apparatus according to any one of claims 4 to 12, wherein said heating means (4) comprises a hob (4) .