GB2218328A

GB2218328A - Steam cooking apparatus

Info

Publication number: GB2218328A
Application number: GB8910762A
Authority: GB
Inventors: Edward Mckinley Moffat
Original assignee: E & R Moffat Ltd
Current assignee: E & R Moffat Ltd
Priority date: 1988-05-13
Filing date: 1989-05-10
Publication date: 1989-11-15
Anticipated expiration: 2009-05-10
Also published as: GB2218328B; GB8811375D0; GB8910762D0

Abstract

A cooking apparatus (100) comprises a heating chamber (25) for containing food items to be heated, a steam generator (104) and supply means (18) for supplying steam from the steam generator (104) to the heating chamber (25). The steam generator (104) comprises a steam generating chamber (15) having a normally closed closure device (17) which is openable or removable from within the heating chamber (25) to enable access to the steam generating chamber (15) from within the heating chamber for cleaning and/or maintenance purposes. <IMAGE>

Description

Cooking Apparatus This invention relates to cooking apparatus, e.g. for processing and reconstituting food items, of the kinO comprising a heating chamber for containing fooc items to be heated, a steam generator having a steam generating chamber and water heating means energisable to generate steam from water supplied to the steam generating chamber, and supply means for supplying steam generated Dy the steam generator to the heating chamber.

A known cooking apparatus of the kind referred to is described in GB-A-2176695. In this known cooling apparatus the steam generator is positioned at one side of tne heating chamber and the steam generating chamber is provided with an outlet tube whicn extends vertically upwards therefrom and passes through tne top of the apparatus. This outlet tube has a screwed closure cap which is removable to gain access to the steam generating chamber for decalcination purposes. However the outlet tuDe is of relatively small diameter and accordingly it is aifficult to obtain efficient cleaning of the steam generating chamber.

The present invention sees to provide cooing apparatus of the kind referred to in which access to the steam generator is facilitatec.

According to one aspect of the present invention, there is provided cooking apparatus of the kind referred to wherein the steam generating c.!a,.lber has an access opening which is closed, during normal operation of the apparatus, by a closure device, the closure device being openable or removable from within the heating chamber so that the steam generating chamber opens into the heating chamber via the access opening whereby affording access to the steam generating chamber from within the heating chamber for cleaning ana/or maintenance purposes.

Conveniently the steam generator is mounted at the bottom of the heating chamber and the closure device is provided at the top of the steam generating chamDer. In this case the closure device suitably provides at least part of a oase for the heating chamber.

Preferably the steam generator is mounted in an opening in a wall, preferably the bottom wall, of the heating chamber.

Preferably said supply means comprises a conduit connecting the steam generating chamber to the heating chamber.

Preferably an impeller is mounted in the heating chamber for distributing air andjor steam within the heating chamber. When said supply means comprises saic conauit, the latter is preferably arranged to direct steam towards the impeller. Conveniently the heating chamber comprises a food-containing first compartment ana, in communication therewith, a secona compartment housing said impeller and/or an air heating aevice, e.g. an electric heating element.

Suitably the cooking apparatus incudes condensing means and steam escape means for allowing steam to escape from the heating chamber for supply to said condensing means. Preferably the condensing means incluaes a spray device for spraying liquid on the escaping steam and liquid supplying means for supplying liquid to tne spray device.

Preferably the liquid supplying means includes a liquid reservoir and a liquid supply line incorporating a control valve for supplying liquid, when the control valve is open, to the liquid reservoir and the spray device, liquid from -the liquid reservoir supplying tne spray device for a period of time after closure of the control valve.

Preferably the cooking apparatus incluaes automatic control means for de-energising said water heating means and closing said control valve when sufficient steam has been generated in .the heating chamber. The provision of the liquid reservoir ensures that steam which continues to escape from the heating chamber via the steam escape means for a short period of time after de-energisation of the water heating means will continue to be condensed by the spray device from liquid stored in the liquid reservoir at least until the liquid reservoir is emptied.Immediately the control valve is opened again, the liquid reservoir will be replenished with liquid Preferably the control means further comprises temperature sensing means, e.g. at least one temperature sensor, for sensing the temperature of air and/or steam in said steam escape means.

Conveniently the cooking apparatus includes means for araining liquid andior condensed steam from the condensing means, the heating chamber and/or the steam generator.

SuitaDly the steam escape means comprises a condenser tube and a smaller diameter breather tube connected between the conaenser tube and the heating chamDer.

According to another aspect of the present invention cooking apparatus of the kind referred to is characterised in that the cooking apparatus further comprises condensing means and steam escape means for allowing steam to escape from the heating chamber for supply to said condensing means, the condensing means comprising a spray device for spraying escaping steam with liquid, a liquid reservoir and a liquid supply line incorporating a control valve for supplying, when the control valve is open, liquid from a liquid source to the liquid reservoir and the spray device, liquid from the liquid reservoir supplying the spray device for a period of time after closure of the control valve.

An embodiment of the invention will now be described, by way of example, with particular reference to the accom panying arawings, in which: Figure 1 is a schematic side view of cooking apparatus according to the invention, and Figure 2 is a schematic horizontal sectional view of the cooking apparatus shown in Figure 1.

Figures 1 and 2 show cooking apparatus accoraing to the invention in the form of a convection oven 10 comprising a heating chamber 25 having an access door, a steam generator 104 and a steam condensing device 101. The oven 10 is provided with controls (not shown) for operating the oven so as to heat or cook fooastuffs placed in the heating chamber 25 by steam, hot air or a mixture of steam ana hot air. An oven thermostat and a timer are aisosuitably provided.

The heating chamber 25 is divided by a partition 21 into a food-receiving compartment 105 and a heater compartment 28. The partition 21 has a circular opening 1ú3 therein so that the compartments 26 and 102 are in communication with each other. within the neater compartment 26 there is housed an air heater 27, e.g. in the form of an electric heating element, and an impeller 22 of a fan driven by an electric motor 23 located outside the heating chamber 25.

The bottom wall of the heating chamber 25 has an opening therein in which the steam generator 104 is mounted. The steam generator 104 comprises a steam generating chamber 15 in the form of an open-toppea reservoir provided with a removable or openable cover or lid 17, typically secured in position by at least one locking screw 16, and water heating means 13, e.g. in the form of an electric immersion heater or a gas operated neater. A steam outlet pipe 18 is arranged between the chamber 15 and the heater compartment 28 for supplying steam generated in tne chamber 15 to the compartment 26 and directing the suppliea steam towards tne impeller 22.Water is supplied to the chamber 15 from a water inlet 7 connected to a mains supply (not shown) and an inlet conduit 12, flow of water from the inlet 7 to the conduit 12 being controlled by a valve 6. The level 14 of water in the chamber is automatically controlled with the aid of electronic water lever probes 24 and the motor actuated valve 6. A steam generator drain pipe 11 incorporating a normally closed valve 10 is connected to a main drain 9.

The main drain 9 is connected to a condenser tube 26 extending vertically to the top of the oven 100 and dyeing open at its upper end to provide a vacuum relief. Teing into the condenser tube 26 are a bottom drain 20 for the heating chamber 25 and a relatively small diameter breather tube 19 also communicating with the heating chamber but in the upper part thereof. The breather tube 19 includes an upper steam temperature sensor 2 and a lower steam/air temperature sensor 5.

The steam condensing device 101 comprises a spray Jet device 4 for spraying steam in the condenser tuce 26 wilt water, a liquid reservoir 3, a conduit 105 for supplying the reservoir 3 and jet device 4 with water ana a motor controlled valve 8 for controlling tne flow of water between the mains water inlet 7 ana the conduit 105.

Automatic control means are provided for controlling the opening and closing of the valves 6 ana 8 and tne energisation and de-energisation of the water heating means.

Wnen the oven 100 operates in its steam only" mode ano with the timer at a aesirea setting, the steam generating chamber 15 is automatically filled to the correct level 14 with water (as previously described) and tne water heating means 13 is energised. At the same time as the water heating means 13 is energised, the valve 8 is automatically opened to supply water via the conduit 1 to the spray jet device 4. After a period of time, steam is generated in the chamber 15 and is conveyed via the steam outlet pipe 18 to the heater compartment 28 of the heating chamber 25. The impeller 22 directs the steam through the opening 103 and distributes it around the food-receiving compartment 102.

When the compartment 102 is full of steam, some of the steam escapes through the bottom drain 20 and the breather tube 19. The presence of steam in the breather tube 1S is detected by the sensor 2 and, Dy means of the automatic control means, the water heating means 13 is de-energised.

At tne same time the valve 8 is automatically closed. Even though the water heating means 13 is de-energiseo, steam already in the breather tube 19 continues down the Dreather tube 19 and enters the condenser tube 26 where it is condensed by cold water from the jet device 4. The water from the jet device 4 and any condensed steam flows into the main drain 9.

It will be appreciated that there is a time lag between the time that the water heating means is de-energised and the time that steam ceases to flow aown tne breather tube 19 into the condenser tube 26. This is the reason for the presence of the reservoir 3. When the valve 6 is open, water from the mains inlet 7 supplies both the jet device 4 and the reservoir 3 which is closed at the top. Air trapped in the top of the reservoir is therefore pressurised. When the valve 8 closes, the excess air pressure in the reservoir 3 forces water out of the reservoir and through the jet device 4 for an extended period of time after closure of the valve 6. Surplus steam passing into the condenser tube 26 is therefore condensed by the liquid from the reservoir 3.In addition the water issuing -from the jet device 4 serves to cool the condenser tube 26 and prevents the heat in it affecting the sensitivity of the temperature sensor 5.

Operation of the oven 100 in its "steam/air" mode is similar to operation in the "steam only mode with the exception that the air heater 27 is also energisea and heats the steam/air to a much higher temperature. The water heating means 13 is then controlled by the sensor 5 (instead of the sensor 2) and the air heater is controlled by an oven thermostat (not shown) in the compartment 102.

When the oven is in its "hot air" mode, the steam generator drain valve 10 is automatically opened to purge the steam generating chamber 15 of steam. Energisation of the air heater 27 is controlled by the oven thermostat.

When the oven is in its "off/drain" mode, the valve 10 is automatically opened and steam is purgea from tne chamber 15.

The provision of the removable cover or lid 17, accessible from the food-receiving compartments, facilitates cleaning and/or maintenance of the steam generator 103. In particular the steam generating chamber 15 is liable to acquire lime scale and water impurity deposits.

These deposits accumulate over a period of time if not removed and affect the operating efficiency and hygiene of the cooling apparatus. Since the lid 17, is easily removable by unscrewing the screws 16, any deposits in the chamber 15 can be readily and easily manually removed. It will be appreciated that the entire steam generating chamber 15 is accessible on removal of the lid 17 because of the large cross-sectional area of the "open" top of the chamber 15. In other embodiments of the invention different types of "closures" may be provided for the chamber 15 - e.g. a pivoting or sliding closure lockable in a closed position by suitable releasable locKing means. It is also feasible, although not preferred, for the steam generator to be mounted at the side of the chamber 25 within a side opening of the chamber 25. In this case an access opening in the steam generator would be provided accessible from the heating chamber.

The provision of the reservoir 3 ensures that water is supplied to the jet device 4 for a period of time after the water heating means 13 is de-energised and the valve 8 closed.

Claims

1. Cooking apparatus comprising a heating chamber ror containing food items to be heated, a steam generator having a steam generating chamber and water heating means energisable to generate steam from water supplied to tne steam generating chamber, and supply means for supplying steam generated by the steam generator to the heating chamber, wherein the steam generating chamber has an access opening which is closed, during normal operation of the cooking apparatus, by a closure aevice, the closure device being operable or removable from within the heating chamber so that the steam generating chamber opens into tne heating chamber via the access opening whereby affording access to the steam generating chamber from within the heating chamber for cleaning and/or maintenance purposes.

2. Cooking apparatus according to claim 1, in which the steam generator is mounted at the bottom of the heating chamber and the closure device is provide: at the top or tne steam generating chamDer.

3. CooKing apparatus according to claim 2, in which the closure device proviaes at least part of a baste for the heating chamber.

4. Cooking apparatus according to any one or claims 1 to 3, in which the steam generator is mounted in a wall opening in a wall of the heating chamber.

5. Cooking apparatus according to any one of tne preceding claims, comprising locking means. accessible from within the heating chamber, for reieasably locking the closure device in its closure position closing said access opening.

6. Cooking apparatus according to claim 5, in which said locking means comprises at least one screw-tnreauea locking aevice.

7. Cooking apparatus according to any one of tne preceding claims, in which said supply means comprises a conduit connecting the steam generating chamber to the heating chamber.

8. Cooking apparatus according to any one of the preceding claims, in which an impeller is mounted in the heating chamber for distributing air and/or steam within the heating chamber.

9. Cooking apparatus according to claim U when dependent on claim 7, in which the said conduit is arranged to direct steam towards the impeller.

10. Cooking apparatus according to claim 8 or 9, in which the heating chamber comprises a food-containing first compartment and, in communication therewith, a second compartment housing said impeller and/or an air heating device.

11. Cooking apparatus according to any one cf the preceding claims, including condensing means and steam escape means for allowing steam to escape from the heating chamber for supply to said condensing means.

12. Cooking apparatus according to claim 11, in which the condensing means includes a spray device for spraying liquid on the escaping steam and liquid supplying means for supplying liquid to the spray device.

1,3. Cooking apparatus according to claim 12, in which the liquid supplying means includes a liquid reservoir and a liquid supply line incorporating a control valve for supplying liquid, when the control valve is open, to the liquid reservoir and the spray device, liquid from the liquid reservoir supplying the spray device for a period of time after closure of the control valve.

14. Cooking apparatus according to claim 13, incluaing automatic control means for de-energising said water heating means and closing said control valve when sufficient steam has been generated in the heating chamber.

15. Cooking apparatus according to claim 14, in which the control means further comprises temperature sensing means for sensing the temperature of air ana/or steam in said steam escape means.

16. Cooking apparatus according to any one of claims 11 to 15, including means for draining liquid and/or condensed steam from the condensing means, the heating chamber and/or the steam generator.

17. Cooking apparatus according to any one of claims 11 to 16, in which the steam escape means comprises a condenser tube and a smaller diameter breather tube connected between the condenser tube and the heating chamber.

16. Cooking apparatus constructed and arranged substantially as herein described with reference to, and as illustrated in, Figures 1 and 2 of the accompanying draw i ngs.

19. Cooking apparatus comprising a heating chamber for containing food items to be heated, a steam generator having a steam generating chamber and water heating means energisable to generate steam from water supplied to the steam generating chamber, d supply means for supplying steam generated by the steam generator to the heating chamber, wherein the apparatus further comprises condensing means and steam escape means for allowing steam to escape from the heating chamber for supply to said condensing means, the condensing means comprising a spray device for spraying escaping steam with liquid, a liquid reservoir and a liquid supply line incorporating a control valve for supplying, when the control valve is open, liquia from a liquid source to the liquid reservoir and the spray device, liquid from the liquid reservoir supplying the spray device for a period of time after closure of the control valve.