GB2609666A

GB2609666A - Oven

Info

Publication number: GB2609666A
Application number: GB2111673.6A
Authority: GB
Inventors: Burnett Albert
Original assignee: Individual
Current assignee: Individual
Priority date: 2021-08-13
Filing date: 2021-08-13
Publication date: 2023-02-15
Also published as: GB202111673D0

Abstract

An oven comprising: an oven chamber including a side inner wall and a rear inner wall 200; at least one heating element configured to heat the chamber; and a spraying device having a liquid outlet, such as a nozzle 230, positioned so that, in use, the spraying device sprays liquid from the outlet to impinge against the heated rear inner wall to generate steam inside the oven chamber. The liquid outlet may be positioned within the chamber on the side inner wall so as to spray in a direction parallel with or away from the side wall and directed closer to the ceiling than the floor. This may be achieved by positioning the outlet closer to the chamber ceiling than the floor. The spray device may also comprise an insulating casing 240 and a liquid storage section connected between a purified water source and the liquid outlet. A flow controller 190 may control liquid flow to the storage device when the spraying system is not operational, either using a timing device or manually. The rear inner wall may comprise a deflector or diffuser with fins.

Description

OVEN

The invention relates to an oven, preferably a deck oven, and to a method of generating steam inside an oven, preferably inside a deck oven.

It is known to use steam inside a deck oven to improve the finish of baked bread.

According to a first aspect of the invention, there is provided an oven comprising: a hollow oven chamber including a side inner wall and a rear inner wall; at least one heating element configured to be operable to heat the oven chamber; and a liquid spraying device connectable to a liquid source, wherein the liquid spraying device includes a liquid outlet positioned so that, in use, the liquid spraying device is operable to spray liquid from the liquid outlet to impinge against the heated 15 rear inner wall to generate steam inside the oven chamber.

The liquid source may be a water source. The liquid source may be a purified water source, such as a filtered, distilled or deionised water source.

In use, the oven chamber may contain one or more food products.

When the or each heating element is operated to heat the oven chamber, the heat inside the oven chamber heats up the inner walls of the oven chamber, including the rear inner wall. When the liquid spraying device is operated to spray liquid against the heated rear inner wall, steam is generated by atomisation of the sprayed liquid taking place as a result of the high temperature of the rear inner wall. In turn the generated steam spreads away from the rear inner wall throughout the oven chamber to envelope the food product(s) inside the oven chamber.

The provision of the liquid spraying device in the invention provides the oven with a steam generation mechanism with low energy, size and cost requirements. In addition the spraying of the liquid can be controlled to provide consistent steam generation and thereby provide accurate steaming conditions for the food product(s).

Also, the steam produced by the oven of the invention is 'wet' steam, which means that there is a greater moisture content per unit volume than externally generated steam that is circulated into a conventional oven. The generation of the 'wet' steam provides an operator with better control over the steaming conditions inside the oven chamber, which in turn produces the desired food steaming results with less effort. In addition, 'wet' steam is more desirable because removal of the 'wet' steam by means of an oven damper or opening the oven door is more efficient than removal of 'dry' steam due to the expanding nature of 'wet' steam under heated conditions.

Furthermore, external extraction equipment can greatly expedite the extraction of the 'wet' steam to further facilitate removal of the 'wet' steam from the oven chamber to prepare for the next cooking cycle.

In contrast, steam generation in a conventional oven is carried out by generating the steam outside the oven chamber and circulating the generated steam into and around the oven chamber. However, such steam generation not only results in less accurate steaming conditions in comparison to the steaming conditions produced by the oven of the invention, but also is more costly due to the high energy requirements of the equipment used to generate steam and circulate steam into and around the oven chamber. Furthermore, the equipment required to generate and circulate steam adds significant size and cost to the conventional oven.

It will be understood that the oven of the invention may be manufactured by building a new oven from scratch or by retrofitting the liquid spraying device into an existing 20 oven.

The liquid outlet may be positioned in different locations so long as its position enables operation of the liquid spraying device to spray liquid from the liquid outlet to impinge against the heated rear inner wall to generate steam inside the oven chamber. In a preferred embodiment of the invention, the liquid outlet is positioned inside the oven chamber. In embodiments of the invention, the liquid spraying device may be positioned on or through the side inner wall.

In further embodiments of the invention, the liquid outlet may be positioned so that, in use, the liquid spraying device is operable to spray liquid from the liquid outlet to impinge against the rear inner wall and in a direction that is parallel with or away from the side inner wall. This prevents the sprayed liquid from cooling the side inner wall that may include or may be associated with one or more temperature sensors, thus avoiding temperature feedback issues and false or inaccurate temperature readings.

In still further embodiments of the invention, the oven chamber may include a ceiling and a floor, and the liquid outlet may be positioned so that, in use, the sprayed liquid from the liquid outlet is directed to be closer to the ceiling than the floor. In such embodiments, the liquid outlet may be positioned to be closer to the ceiling than the floor. Conveying the sprayed liquid closer to the oven's ceiling provides a more consistent steam generation in comparison to conveying the sprayed liquid closer to 5 the oven's floor.

The inventor has identified a need to reduce water evaporation loss from the liquid outlet. Due to the exposure of the liquid outlet to the heat inside the oven chamber, there is a risk of water evaporation loss from the liquid outlet. This in turn may affect the spraying performance and the spray period per cooking cycle of the liquid spraying device and thereby may result in inaccurate steaming conditions inside the oven chamber.

In embodiments of the invention, the liquid spraying device may include a heat insulating casing arranged to enclose the liquid outlet, wherein the heat insulation casing may include an opening for passage of the sprayed liquid from the liquid outlet. The heat insulating casing shields the liquid outlet from the heat inside the oven chamber to reduce water evaporation loss from the liquid outlet.

In further embodiments of the invention, the liquid spraying device may include: a liquid storage section operably connected to the liquid outlet so that the sprayed liquid from the liquid outlet is drawn from the liquid storage section, wherein the liquid storage section is connectable to the liquid source; and a flow controller configured to selectively control liquid flow from the liquid 25 source to the liquid storage section.

The flow controller may include at least one flow control valve. The flow controller may include a programmable control unit.

The flow controller may be configured to direct liquid to flow from the liquid source to the liquid storage section in order to compensate for the water evaporation loss. Specifically, any liquid lost from the liquid storage section due to water evaporation loss is replaced by the incoming liquid from the liquid source. Thus, by ensuring that the liquid storage is regularly filled with a sufficient amount of liquid, the liquid spraying device is capable of exhibiting a consistent spraying performance when the sprayed liquid from the liquid outlet is drawn from the liquid storage section.

Preferably the flow controller is configured to selectively direct liquid to flow from the liquid source to the liquid storage section when the liquid spraying device is not in operation to spray liquid from the liquid outlet. This provides a controlled way of compensating for the water evaporation loss during a period between successive steam generation operations. The flow controller is configured to selectively direct liquid to flow from the liquid source to the liquid storage section prior to commencement of the liquid spraying operation.

Operation of the flow controller may be automated. For example, the flow controller may include a timer device, and the flow controller may be configured to, using the timer device, periodically direct liquid to flow from the liquid source to the liquid storage section when the liquid spraying device is not in operation to spray liquid from the liquid outlet. This provides an automatic way of compensating for the water evaporation loss during a period between successive steam generation operations, without requiring user intervention.

Operation of the flow controller may be manual. For example, the flow controller may be configured to be manually operable to direct liquid to flow from the liquid source to the liquid storage section when the liquid spraying device is not in operation to spray liquid from the liquid outlet. This enables a user to initiate compensation for the water evaporation loss whenever required, which can be beneficial in the event of a higher than expected water evaporation loss.

The rear inner wall may include a deflector or diffuser, e.g. a steam deflector or diffuser. The liquid outlet may be positioned so that, in use, the liquid spraying device is operable to spray liquid from the liquid outlet to impinge against the heated deflector or diffuser to generate steam inside the oven chamber. The use of the deflector or diffuser provides a greater surface area to promote atomisation when the sprayed liquid impinges against the deflector or diffuser. The deflector or diffuser may be shaped in different ways to obtain a desired surface area of the rear inner wall. For example, the deflector or diffuser may include a plurality of fins.

In embodiments of the invention, the liquid outlet may be, but is not limited to, a spray nozzle.

In further embodiments of the invention, the oven may include a liquid source connected to the liquid spraying device. In such embodiments, the liquid source may be a purified water source, such as a filtered, distilled or deionised water source.

According to a second aspect of the invention, there is provided a method of generating steam inside an oven according to any one of the first aspect of the invention and its embodiments, wherein the method comprises the steps of: operating the or each heating element to heat the oven chamber; operating the liquid spraying device to spray liquid from the liquid outlet to impinge against the heated rear inner wall to generate steam inside the oven chamber.

The features and advantages of the first aspect of the invention and its embodiments apply mutatis mutandis to the second aspect of the invention and its embodiments.

Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, and the claims and/or the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and all features of any embodiment can be combined in any way and/or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and/or incorporate any feature of any other claim although not originally claimed in that manner.

Preferred embodiments of the invention will now be described, by way of non-limiting 25 examples, with reference to the accompanying drawings in which: Figures 1 and 2 show cross-sectional and exploded views of components of a water spraying device of an oven according to an embodiment of the invention; Figure 3 shows a schematic view of a water spraying device of an oven 30 according to an embodiment of the invention; Figure 4 shows a steam deflector of an oven according to an embodiment of the invention; and Figure 5 illustrates a steam generation operation of an oven according to an embodiment of the invention.

The figures are not necessarily to scale, and certain features and certain views of the figures may be shown exaggerated in scale or in schematic form in the interests of clarity and conciseness.

The following embodiments of the invention are described with reference to a deck oven for baking bread. It will be appreciated that the following description applies mutatis mutandis to other types of ovens, other types of food products and/or other 5 types of oven cooking processes.

A deck oven according to an embodiment of the invention is shown in Figures 1 to 4 and is for baking bread. The deck oven comprises a hollow oven chamber, a heating element and a water spraying device.

The oven chamber is defined by side inner walls, a rear inner wall 200, a front door, a ceiling and a floor. In use, the front door may be opened to add dough to the oven chamber or remove baked bread from the oven chamber. The deck oven includes a tray located inside the oven chamber. In use, the tray is used to hold the dough or bread during the baking process. In other embodiments, the deck oven may include multiple trays inside the oven chamber. It will be appreciated that the tray is optional and that the dough can be placed directly on the floor for baking or in a container.

In use, the heating element is operable to heat the oven chamber during the baking process. The heating element may be attached to the ceiling or may be located outside the oven chamber.

The water spraying device includes a spray nozzle 230 that is threaded into a spray 25 nozzle fitting 210. A copper sealing washer 220 provides a water-tight seal between the spray nozzle 230 and the spray nozzle fitting 210. In use, the spray angle of the spray nozzle 230 is preferably, but not limited to, 1100, as shown in Figure 1.

Figure 2 shows the configuration of various components of the water spraying device.

A copper water delivery tube 310 is connected to the spray nozzle fitting 210 via a bulkhead adapter fitting 280. A copper sealing washer 250 provides a water-tight seal between the bulkhead adapter fitting 280 and the spray nozzle fitting 210. The bulkhead adapter fitting 280 extends through a hole in the side inner wall. A lock nut 260 secures the bulkhead adapter fitting 280 to the side inner wall. A stainless steel external toothed shakeproof washer 270 prevents the bulkhead adapter fitting 280 from slipping during tightening. An olive 290 creates a water-tight seal between the water delivery tube 130 and bulkhead adapter fitting 280. A compression lock nut 300 secures the olive 290 to the water delivery tube 310 and seals the olive 290 to the bulkhead adapter fitting 280.

In use, the water delivery tube 310 is connected to a filtered water source, as described in further detail below. This allows the water delivery tube 310 to function as a water storage section that stores filtered water so that the spray nozzle 230 directly draws water stored in the water delivery tube 310 when spraying water. It will be appreciated that other types of water sources may be used in place of the filtered water source.

Figure 3 shows a schematic view of the water spraying device, where the bulkhead adapter fitting 280 is secured to the side inner wall to position the spray nozzle 230 inside the oven chamber adjacent the side inner wall and near the ceiling. The spray nozzle 230 is positioned to face the rear inner wall 200 so that, in use, the water spraying device is operable to spray a flat metered supply of filtered water at a constant flow rate from the spray nozzle 230 towards the rear inner wall 200.

The position of the spray nozzle 230 is such that, as the sprayed water travels from the spray nozzle 230 to the rear inner wall 200, the sprayed water from the spray nozzle 230 travels close to the ceiling and in a direction that is away from the side inner wall. By directing the sprayed water to avoid the side inner wall, unwanted significant cooling of the side inner wall is avoided, thus permitting accurate temperature measurements by a temperature sensor (or temperature sensors) associated with the side inner wall. It will be appreciated that in practice a small amount of sprayed water may land on the side inner wall, which would have a minimal impact on the temperature sensor(s) associated with the side inner wall.

A Water Regulations Advisory Scheme (WRAS) approved water hose 380 is connected to a water mains supply. A filter bypass head 170 and a water filter 140 provides filtration of the water to prevent oxidation of minerals fouling the spray nozzle 230. The water hose 380 is connected to a water pressure regulator 160 via a stop cock valve 360 (for isolating the water mains supply), a water drain down valve 150 (for draining the water spraying device or removing stagnant water from the water spraying device) and a water pipe 370. Another water pipe 370 connects the water pressure regulator 160 to a pair of solenoid control valves 180. In other embodiments, a single solenoid control valve 180 may be used instead of the pair of solenoid control valves 180.

The water pressure regulator 160 controls the pressure and flow rate of the water supplied to the water delivery tube 310 and the spray nozzle 230. The solenoid control valves 180 are flow control valves that can be opened and closed in tandem to either permit or block the flow of water from the water pressure regulator 160 to the water delivery tube 310 and the spray nozzle 230.

The water delivery control unit 190 is a programmable control unit for controlling the operation of the solenoid control valves 180. The water delivery control unit 190 includes: a line voltage input 320 for operating the solenoid control valves 180; a low voltage input for operating a system relay; and an operator-controlled input 340 to activate the spraying so that steam generation can be requested on demand. The operator-controlled input 340 may be linked to a button that can be pressed by the operator.

In this way the solenoid control valves 180 and the water delivery control unit 190 together function as a flow controller for controlling the flow of water from the water mains supply to the water delivery tube 310 and the spray nozzle 230.

The rear inner wall 200 includes a steam diffuser 200 having a plurality of vertical and parallel fins, as shown in Figure 4.

An example baking process is described as follows with reference to Figure 5.

Initially the heating element is operated to heat the oven chamber. This causes the inner walls of the oven chamber to heat up. As the heat bakes the dough in the tray, the water spraying device is operated to spray water against the heated steam diffuser 200. The sprayed water has a flat fan spray pattern comprised of a central section of water droplets 120 flanked by partially vaporised water spray 110, which in turn is flanked by vaporised water 100. A preferred distance 130 from the spray nozzle 230 to the steam diffuser 200 is 430 mm.

As the spray water impinges against the steam diffuser 200, steam is generated by atomisation of the sprayed water due to the high temperature of the steam diffuser 200. The generated steam spreads away from the steam diffuser 200 to envelope 35 the bread on the tray so that the bread can undergo steaming for improved finishing.

In comparison to a flat rear inner wall, the arrangement of the fins of the steam diffuser 200 provides a greater surface area to promote atomisation when the sprayed water impinges against the steam diffuser 200. It will however be appreciated that the invention will also work with a flat rear inner wall.

During the baking process, water evaporation loss from the spray nozzle 230 may take place while the spray nozzle 230 is not spraying water. This is due to the exposure of the spray nozzle 230 to the heat inside the oven chamber. The water evaporation loss may negatively affect the spraying performance of the water spraying device so as to cause inaccurate steaming conditions inside the oven chamber.

To reduce water evaporation loss, the water spraying device includes a heat insulating casing in the form of a jacket 240 (or sleeve) that encloses the spray nozzle to shield it from the heat inside the oven chamber. An opening is formed in the heat insulating jacket to permit passage of the sprayed water from the spray nozzle. The heat insulating jacket may be made of a chromium-nickel austenitic alloy.

The water delivery control unit 190 includes a timer device that operates on a timer-controlled open loop feedback 350. The timer device is set to automatically open the solenoid control valves 180 to the water delivery tube 310 in order to temporarily backfill the water delivery tube 310 with water to compensate for water evaporation loss from the spray nozzle 230. The timing of the water backfilling is controlled so that enough water is delivered to the water delivery tube 310 to replace the lost water without causing water to be sprayed from the spray nozzle 230. The timer device may be set to automatically carry out the water backfilling on a periodic basis.

The deck oven of the invention therefore has an energy-efficient and cost-effective steam generation mechanism in comparison to conventional ovens. The ability to control the flow of the sprayed water enables consistent steam generation to reliably 30 and repeatedly provide accurate steaming conditions.

Exemplary technical specifications of an oven according to an embodiment of the invention are set out as follows: * Water Pressure Gauge: Maximum Input Pressure 6.0 bar * Water Filter: Particulate size removal down to 0.5 pm * Minimum Mains Water Pressure: 1.5 bar * Water Pressure Setting / Working Water Pressure: 1.5 bar * Spray Nozzle Pattern: Flat * Spray Angle: 1100 * Spray Nozzle Flow Factor: 015 * Spray Nozzle Diameter: 0.79 mm * Spray Nozzle Flow Rate: 14 litres per minute (LPM) at 1.5 bar pressure 5. Maximum Steaming Period per Cooking Cycle: 5 Seconds * Minimum Oven Temperature for Steam Operation: 170 degrees Celsius / 338 degrees Fahrenheit * Maximum Oven Chamber Cubic Capacity: 0.257m3 (Based on three 75 cm x 45 cm Baking Tray Capacity) * Maximum Oven Chamber Size: 1.410 Metres Width, 0.911 Metres Depth, 0.2 Metres Height * Electrical Requirement: 230v AC / 24v AC or DC * Electrical Energy Consumption: 230v AC -30.8VA -(0.0308 Watts) Peak * Electrical Energy Consumption: 24v AC or DC -2VA (0.002 Watts) Continuous / 3VA Peak (0.003 Watts) * Peak Electrical Power Consumption Time = Maximum Steaming Period It will be appreciated that any aforementioned numerical value is merely intended to help illustrate the working of the invention and may vary depending on the 20 requirements of the invention.

The listing or discussion of an apparently prior published document or apparently prior published information in this specification should not necessarily be taken as an acknowledgement that the document or information is part of the state of the art or 25 is common general knowledge.

Preferences and options for a given aspect, feature or parameter of the invention should, unless the context indicates otherwise, be regarded as having been disclosed in combination with any and all preferences and options for all other aspects, 30 features and parameters of the invention.

Claims

CLAIMS1. An oven comprising: a hollow oven chamber including a side inner wall and a rear inner wall; at least one heating element configured to be operable to heat the oven chamber; and a liquid spraying device connectable to a liquid source, wherein the liquid spraying device includes a liquid outlet positioned so that, in use, the liquid spraying device is operable to spray liquid from the liquid outlet to impinge against the heated 10 rear inner wall to generate steam inside the oven chamber.
2. An oven according to Claim 1 wherein the liquid outlet is positioned inside the oven chamber.
3. An oven according to any one of the preceding claims wherein the liquid spraying device is positioned on or through the side inner wall.
4. An oven according to any one of the preceding claims wherein the liquid outlet is positioned so that, in use, the liquid spraying device is operable to spray liquid 20 from the liquid outlet to impinge against the rear inner wall and in a direction that is parallel with or away from the side inner wall.
5. An oven according to any one of the preceding claims wherein the oven chamber includes a ceiling and a floor, and the liquid outlet is positioned so that, in use, the sprayed liquid from the liquid outlet is directed to be closer to the ceiling than the floor.
6. An oven according to Claim 5 wherein the liquid outlet is positioned to be closer to the ceiling than the floor.
7. An oven according to any one of the preceding claims wherein the liquid spraying device includes a heat insulating casing arranged to enclose the liquid outlet, wherein the heat insulation casing includes an opening for passage of the sprayed liquid from the liquid outlet.
8. An oven according to any one of the preceding claims wherein the liquid spraying device includes: a liquid storage section operably connected to the liquid outlet so that the sprayed liquid from the liquid outlet is drawn from the liquid storage section, wherein the liquid storage section is connectable to the liquid source; and a flow controller configured to selectively control liquid flow from the liquid source to the liquid storage section.
9. An oven according to Claim 8 wherein the flow controller is configured to selectively direct liquid to flow from the liquid source to the liquid storage section when the liquid spraying device is not in operation to spray liquid from the liquid 10 outlet.
10. An oven according to Claim 9 wherein the flow controller includes a timer device, and the flow controller is configured to, using the timer device, periodically direct liquid to flow from the liquid source to the liquid storage section when the liquid spraying device is not in operation to spray liquid from the liquid outlet.
11. An oven according to Claim 9 or Claim 10 wherein the flow controller is configured to be manually operable to direct liquid to flow from the liquid source to the liquid storage section when the liquid spraying device is not in operation to spray liquid from the liquid outlet.
12. An oven according to any one of the preceding claims wherein the rear inner wall includes a deflector or diffuser, wherein the liquid outlet is positioned so that, in use, the liquid spraying device is operable to spray liquid from the liquid outlet to impinge against the heated deflector or diffuser to generate steam inside the oven chamber.
13. An oven according to Claim 12 wherein the deflector or diffuser includes a plurality of fins.
14. An oven according to any one of the preceding claims wherein the liquid outlet is a spray nozzle.
15. An oven according to any one of the preceding claims including a liquid source connected to the liquid spraying device.
16. An oven according to Claim 15 wherein the liquid source is a purified water source.
17. A method of generating steam inside an oven according to any one of the preceding claims, wherein the method comprises the steps of: operating the or each heating element to heat the oven chamber; operating the liquid spraying device to spray liquid from the liquid outlet to impinge against the heated rear inner wall to generate steam inside the oven chamber.