GB2177897A

GB2177897A - Cooking apparatus

Info

Publication number: GB2177897A
Application number: GB08615101A
Authority: GB
Inventors: Edward Mckinley Moffat
Original assignee: Individual
Current assignee: Individual
Priority date: 1985-06-21
Filing date: 1986-06-20
Publication date: 1987-02-04
Also published as: GB8515777D0; GB2176695B; GB2177897B; GB2176695A; GB8615102D0; GB8615101D0

Abstract

Apparatus for cooking food items comprises a heating chamber (1) provided with an access opening and a door (33) having inner and outer glazing panels (26, 24). The inner glazing panel (26) is dimensioned to completely cover the access opening (50) when the door is closed. <IMAGE>

Description

1 GB 2 177 897 A 1

SPECIFICATION Cooking apparatus

This invention relates to an apparatus for cooking food items. Primarily, but not exclusively, the 70 invention relates to steam cooking apparatus for processing and reconstituting food items.

According to the invention an apparatus for cooking food items comprising a heating chamber, having an access opening, and a door for closing said access opening, is characterised in that the door comprises spaced apart inner and outer glazing panels, the inner glazing panel being dimensioned to completely cover the access opening when the door is in a closed position.

By employing a full area inner glazing panel it is possible to view completely inside the heating chamber, e.g. during use of the apparatus. Heat loss is minimised by employing a multipanel, e.g.

double-glazed, door.

Typically the inner and outer glazing panels have substantially the same area dimensions. Normally the thickness of the panels will bethe same butthe thicknesses of the two panels may be different.

Suitably a sealing gasket is arranged to provide a seal between the access opening and the said inner glazing panel when the door is in its closed position.

Conveniently the sealing gasket is attached to the door.

Preferably the apparatus comprises steam 95 cooking apparatus for processing and reconstituting food items.

An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawing, in which Figure 1 is a schematic side view of steam cooking apparatus according to the invention, Figure 2 is a schematic horizontal sectional view of the apparatus shown in Figure 1, and Figure 3 is a view, on an enlarged scale, of a detail 105 of Figure 2.

The Figures show a steam convection oven, generally designated by the reference numeral 100, comprising a heating chamber 1, a steam generator 2 and a steam condenser 5. The oven 100 is provided with controls (not shown) for operating the oven so as to heat or cook foodstuffs placed in the heating chamber 1 by steam, hot air or a combination of steam and hot air.

The heating chamber 1 includes a vacuum relief tube 15, a steam inlet 3a and an outlet 3b and is provided with a partition 16 separating the chamber 1 into two parts la and lb. Mounted in part la of the heating chamber 1 there are heating means 13, e.g.

an electric heating element or a gas heat exchanger, and an impeller 12 driven by an electric motor 11 for circulation of hot airlsteam within the chamber 1 to enable the heating of food items placed within part lb of the heating chamber. The part lb of the heating chamber 1, which, as mentioned previously, is designed to receive iteris of food to be heated, has an access opening 50 and is provided with an oven thermostat 34 for controlling the temperature inside the chamber 1. The opening 50 is arranged to be closed by means of a double-g lazed door 33 130 having substantially similarly sized, rectangular, spaced-apart inner and outer transparent glazing panels 26 and 24, respectively, suitably of heatresisting glass. The glazing panels 24,26 are periphe,rally spaced apart by spacer means, e.g. a square section stainless steel frame 25, and are peripherally sealed by sealing means, e.g. a silicone seal 28 and a stainless steel channel-section peripheral frame 27. The frame 27 has its inner side longer than its outer side clamping a P-section sealing gasket 29, e.g. of silicone, around the inwardly facing peripheral surface of the glazing panel 26. In the closed position of the door 33 (i.e. as shown in Figures 2 and 3) the sealing gasket 29 is resiliently pressed against the outside of the access opening 50. Since the glazing panel 26 is of full area, the gasket 29 seals against the panel 26 thereby preventing ingress of steam into the space between the glazing panels. The gasket 29 simply pushes into position between the inner side of the frame 27 and the glazing panel 26 and can be speedily renewed without the use of tools. In an alternative embodiment (not shown) a sealing gasket may be positioned around the outside of the access opening 50 so as to seal against the inner glazing panel 26 when the door is in its closed position. A join between the heating chamber 1 and an outer casing panel 23 is fitted with a thermal break 30 in the form of heat resisting material to reduce heat transfer to the outer casing 23. Heat insulation 22 is provided around the chamber 1 internally of the casing 23. Although as shown, the glazing panels are hermetically sealed, the space between the spacedapart glazing panels 24,26 need not be hermetically sealed.

The steam generator 2 comprises a steam generating chamber 2a which has substantially the same vertical extent as the heating chamber 1 and is arranged to supply steam to the latter via the steam inlet 3a atthe top of the heating chamber 1. Independent heating means 36, e.g. in the form of an electric immersion heater or a gas heat exchanger, and an openable drain 38 are provided at the bottom of the chamber 2a and an outlet 31 to the atmosphere extends upwardly from the top of the chamber 2a. An electronic automatic water level control system 37 is provided and includes high and low water level probes 17 for sensing the water level and actuating a flow-control solenoid valve 40 for controlling the supply of water to the chamber 2a. The probes 17 are protected by means of a baffle 21 to reduce the possibility of turbulence of the boiling water, boiled by the heating means 36, affecting the operation of the probes. In use the valve 40 is automatically opened when the low water level probe 17 senses that the water level in the chamber 2a is below a minimum level and water is supplied via inlet pipe 35 to the chamber 2a. When the water level in the chamber 2a exceeds a predetermined maximum value sensed by the high water level probe 17 the valve 40 is automatically closed and supply of water to the chamber 2a ceases.

The outlet 31 to the atmosphere is arranged vertically in line with the steam generating chamber 2a and has an upper end which is closed by a 2 GB 2 177 897 A 2 screwed closure cap 14 which is removable for enabling decalcification of the steam generator 2.

A vertical drain pipe 18 with a drain valve 4 extends from the outlet 3b at the bottom of the heating chamber 1 and a spillage tray 32 is arranged 70 directly beneath the drain pipe 18. A further pipe 43 branches off the drain pipe 18 and extends into, so as to provide a steam inlet to, the steam condenser 5. The steam condenser comprises a reservoir 5a for water provided with a combined overflow and 75 pressure regulating device in the form of an externally screw-threaded tube 6 screwed vertically into the bottom of the reservoir 5a and secured in the desird position, e.g. by welding. To simplify cleaning of the chamber 5, a "hand" hole 39 is formed in the reservoir 5a and is closed by a removable cover 42. The cover 42 is sealed by a gasket 50 a9d has a screw threaded shaft 51 secured thereto. The hole 39 is closed by screwing the shaft into a nut 52 secured to a retaining member 44 secured to the inside of the chamber 5. A bleeder hole 7 is formed in the sidewall of the tube 6, spaced beneath its upper end. Water is supplied to the reservoir 5a by means of an inlet pipe 20 provided with a flow-control solenoid valve 41 and having a bore size greater than the bleeder hole 7 and steam is vented from the reservoir 5a by means of a vent tube 8 having a vent thermostat 9. A by-pass tube 10 connects the heating chamber 1 to the condenser 5, the upper end 1 Oa of the tube opening into the chamber part la and the lower end 10b of the tube opening into the reservoir 5a below the water level 19.

In use, food is placed inside part 1 b of the heating chamber 1, the mode of operation ("steam", "air" or "steam/air") is selected, and the oven is switched on. The timer (not shown) and the oven thermostat 34 are set to appropriate settings and the motor driven impeller 12 recirculates "air" and/or "steam" within the chamber 1.

If "steam" or "steam/air" is selected as the mode of operation, the steam generator 2 comes into operation. The heating means 36 heats the water in the steam generating chamber 2a so that steam is generated and passes into the heating chamber 1 through the steam inlet 3a. The water level control system 37 ensures that the level of water in the steam generating chamber is kept between upper and lower water levels sensed by the probes 17.

If the pressure inside the chamber 1 exceeds a pre-set low pressure, the steam circulating therein is forced through the steam outlet 3b and through the pipes 18 and 43, the lower end of which is positioned beneath the water level 19, into the reservoir 5a. With the steam generator 2 in operation, the valve 41 is open and water is continuously fed into the reservoir 5a through the inlet pipe 20 so that water in the reservoir overflows through the tube 6. The level 19 of water in the reservoir 5a is pre-set by the position that the tube 6 is screwed and fixed in position in the reservoir and is preferably arranged so that the level 19 forthe water, when the latter overflows through the top of the tube 6, is above the end of the pipe 43 so that steam passing through the latter will always have to 130 pass into the water contained in the reservoir 5a. Water contained in the reservoir 5a will also pass out through the tube 6 via the bleeder hole 7. However, since the bore of the pipe 20 is greater in size than the hole 7, the level 19 of water in the reservoir will be maintained at the level of the upper end of the tube 6 provided that water continues to be supplied to the reservoir via the inlet pipe 20. With the water at this level 19, the lower end 1 Ob of the tube 10 is sealed by the water contained in the reservoir 5a.

The injection of steam into the water contained in the reservoir 5a, which occurs, as previously mentioned, when the pressure in the chamber 1 exceeds a pre-set low pressure, will normally condense most of the steam in particular since the continuous supply of cool water to the reservoir 5a ensures that the water in the latter remains relatively cool despite the heating effect of the injected steam. However, in certain cases, particularly towards the end of a cooking cycle, it is not unusual for some of the steam to pass, uncondensed, through the reservoir 5a and to escape into the vent tube 8. The vent thermostat 9 senses the steam in the tube 8 and cuts off the heating means 36 of the steam generator resulting in closure of the valve 41. As the temperature sensed bythe thermostat 9 falls, the heating means 36 is automatically turned back on and the valve 41 is automatically opened.

The water level 19 in the reservoir 5a determines the pressure within the heating chamber 1 at which steam is injected into the water reservoir 5a. In particular the lower pressure within the chamber 1 which must be exceeded to enable steam injection is dependent on the height of the water level 19 above the bottom of the outlet of the pipe 43 extending into the reservoir 5a. This water level 19 is pre-set during fixing of the tube 6 in the reservoir 5a.

If "air only" is selected as the mode of operation of the oven, heating means 13 inside the heating chamber 1 becomes operative and impeller 12 recirculates heated air within the chamber 1. Since the heating means 36 is not operational in the "air only" mode, the valve 41 is closed preventing supply of water to the reservoir 5a via the inlet pipe 20. The water level 19 thus drops, as water flows through the bleeder hole 7, thereby opening the lower end 1 Ob of the tube 10 and providing an automatic vent for the heating chamber 1 via the tube 10, the reservoir 5a and the vent tube 8. This venting arrangement eliminates the need for manually operated venting systems. With the water at its lower level in the reservoir 5a, the lower end of the pipe 43 will suitably be above this lower level. The thermostat 9 suitably does not control operation of the heating means 36 and/or valve 41 during "air only" operation.

The tube 10 also acts as a safety valve if a blockage occurs in the pipe 43 or other parts of the drain/condense system with the steam generator operational. In this case, excess steam pressure within the chamber 1 and/or steam generator 2 will cause the steam in the chamber 1 to pass down the by-pass tube 10, through the water sealed opening 3 GB 2 177 897 A 3 of the tube 10 into the water in the reservoir 5a. The steam thus bubbles into the water and passes into the chamber 5 and then into the vent tube 8. The steam passing through the vent tube activates the vent thermostat 9 and cuts off the heating means 36.

To facilitate cleaning and/or general maintenance of the oven, access to the reservoir 5a can be gained via the "hand" hole 39 covered by the removable cover seal 42. The cap 14 can be unscrewed and removed to enable decalcification of the steam generator 2. The drain valve 4 should be in its open position during cleaning of the heating chamber 1 to mimimise the amount of grease and/or spillage entering the steam condenser 5.

Although primarily relating to a steam oven or steam heating apparatus, the invention can relate to othertypes of oven in which an oven or heating chamber door has spaced apart inner and outer glazing panels dimensioned to completely cover the 40 access opening of the heating chamber when the door is in its closed position.

Claims

1. An apparatus for cooking food items comprising a heating chamber, having an access opening, and a door for closing said access opening, characterised in that the door comprises spaced apart inner and outer glazing panels, the inner glazing panel being dimensioned to completely cover the access opening when the door is in a closed position.

2. An apparatus according to claim 1, in which the area dimensions of the inner and outer glazing panels are substantially the same.

3. An apparatus according to claim 1 or 2, in which the inner and outer glazing panels form part of a hermetically sealed double-glazed door.

4. An apparatus according to any of claims 1 to 3, in which a sealing gasket is arranged to provide a seal between the access opening and the inner glazing panel when the door is in its closed position.

5. An apparatus according to claim 4, in which the sealing gasket is attached to the door.

Printed for Her Majesty's Stationery Office by Courier Press, Leamington Spa, 211987. Demand No. 8817356. Published by the Patent Office, 25 Southampton Buildings, London, WC2A lAY, from which copies may be obtained.