AU784398B2 - An oven - Google Patents

Description

P \WPDOCS\AJS\pci\76 I1821 doc-26l I2 -1- AN OVEN Background of the Invention The present invention relates to apparatus for baking flat bread, and in particular an oven for making flat bread, such as a Lebanese bread, pita bread, or the like.

Description of the Prior Art The reference to any prior art in this specification is not, and should not be taken as an acknowledgment or any form of suggestion that the prior art forms part of the common general knowledge in Australia.

Flat bread, such as Lebanese bread, has been baked in a traditional manner for many years. This technique involves heating a clay oven and then placing the dough, which is arranged, in a flat disk-like shape, on a flat clay surface within the oven. The bread is then baked before being removed and allowed to cool.

This process is typically very time consuming because the bread must be manually placed in and removed from the oven. In addition to this, only a limited number of flat breads can be baked at only one time.

A modern solution for baking flat bread, such as Syrian bread has been proposed in US Patent Application No. 4,470,805. This document describes an oven formed from a rotating table that is positioned in an oven and heated, with the heat being confined by a dome shaped cover. In use, dough is placed on the table and cooked within the oven before being subsequently removed.

However, in this technique although the bread becomes more evenly cooked, and multiple pieces can be cooked simultaneously, than in traditional ovens, the oven still requires the dough to be manually loaded and the bread to be manually removed.

This therefore places an extreme limitation of the number of flat breads that can be cooked in a given time and duration.

P \WPDOCSXASpcci\761 doc-2(AJLA)2 -2- Summary of the Present Invention In a first broad form the present invention provides apparatus for baking flat bread, the apparatus including: a) A transport mechanism for receiving a substantially flat portion of dough, and transporting the dough along a transport path to an oven; b) A fluid supply positioned on the transport path for supplying fluid to a first surface of the dough; c) An oven including an endless cooking surface, the endless cooking surface being heated to a predetermined temperature and moving along a cooking path to an outlet in use, the cooking surface being adapted to: i) Receive the dough from the transport mechanism, the first surface of the dough adhering to the cooking surface under action of the fluid; ii) Transport the dough along the cooking path, the dough being cooked at least by contact with the cooking surface; and, iii) Output the baked flat bread from the outlet.

Preferably, the endless cooking surface is formed from a cylinder defining a cylinder axis, the cylinder being mounted for rotation about the cylinder axis.

In this case, the cylinder axis is typically substantially horizontal and aligned substantially perpendicularly to the direction of movement of the dough along the transport path.

The cylinder is usually heated by one or more heating elements positioned between the cylinder and the cylinder axis. In this case, the heater elements will typically be gas heater elements, although electric or other suitable elements may be used.

Preferably the endless cooking surface has high heat conductivity.

p \WP DOCS\AJSe i\761X320 d.c-26W)2 -3- The time taken to transport the dough along the cooking path is usually less than minute, and is preferably between 45 and 50 seconds.

The cooking surface is typically heated to a temperature of at least 250'C, and is preferably heated to a temperature of between 300'C and 350'C.

Typically the cooking path includes additional heaters.

In this case, the additional heaters are preferably positioned outside the cylinder to thereby cook a second surface of the dough, the second surface opposing the first surface and not being in contact with the cooking surface.

The fluid supply usually includes a nozzle adapted to spray fluid on to the first surface of the dough. In this case, the fluid is preferably water.

The transport mechanism is usually formed from an endless belt.

In this case, the endless belt can be movable towards and away from the cooking surface. Accordingly, the endless belt can be urged towards the cooking surface, in use.

Typically, the endless belt being multi-layered and including a heat resistant layer.

The outlet usually includes a member for urging the baked bread away from the cooking surface.

The outlet is typically coupled to a second transport mechanism adapted to transport the baked bread from the outlet to a packing station.

Brief Description of the Drawings Examples of the present invention will now be described with reference to the P XWPDCS\A1S\\5Pri\761X32 docYAWAQ -4accompanying drawing in which:- Figure 1 is a schematic plan view of a system for baking flat bread; Figure 2 is a schematic side view of the oven of Figure 1; Figure 3 is a schematic plan view along the line A-A' of Figure 2.

Detailed Description of the Preferred Embodiments An example of a system for automatically producing flat bread, such as Lebanese bread, will now be described with reference to Figure 1, which is a schematic plan view of a bread making system.

As shown in Figure 1 the system includes a dough making machine 1, a divider 2, a proofer 3 and a roller system 4. Following the roller system 4 is a transport mechanism 5, a spray system 6, an oven 7, and an output transport 8, which directs baked flat bread to a packing station 9, as shown.

In use, the dough maker 1 is used to mix up dough that is then divided into individual dough portions using the divider 2. The dough portions are then transported through the proofer 3 allowing the dough time to prove. This transportation typically takes about 7 minutes.

Once the proved dough has reached the roller system 4, the roller system operates to roll the dough into a flat or laminar circular disk. In this example, the circular disk has a diameter of approximately 25cm, although other sizes can be produced. The flattened circular disk is then transferred to the transport system The operation of the dough mixer 1, the divider 2, the proofer 3 and roller system 4 are well known in the art and will therefore not be described in any further detail.

The transport system 5, the spray system 6 and the oven 7 are shown in more detail in Figures 2 and 3.

P \%VPDOCS\iSAJci\s 76 1120 do.-NAWA)2 As shown, the spray system 6 is formed from a nozzle 10 and a sensor 14, such as an optical or infra-red sensor, that are positioned above a conveyer belt 11. The conveyor belt 11 is entrained around rollers 12, 13, and may be specific to the spray system 6, or alternatively may form a part of the roller system 4, as will be appreciated by a person skilled in the art.

The transport system 5 is formed from the conveyer belt 20, which is entrained around rollers 21, 22, 23, 24, 25, and 26. The rollers 21, 22, 23, 24, 25, and 26 are adapted to maintain the conveyor belt under tension, as well as to drive the conveyor belt in the direction shown by the arrow 41, using a driving system (not shown).

The rollers 23, 24, 25 are mounted on springs (not shown) to cause the conveyer belt to be urged in the direction of the arrow 27. In addition to this, the rollers 23, 24, 25 may be moved to the positions shown by the dotted lines, to thereby disengage the conveyor belt from the oven 7, as will be explained in more detail below.

The oven 7 is formed from a drum 30 that is adapted to act as a cooking surface for cooking the flat bread. Accordingly, the surface of the drum must be heated to an operating temperature, which is typically in the region of 300-350'C. In order to achieve this, a heater unit 33 is positioned inside the drum 30 between the drum and an axis 31 of the drum 30. The drum is formed from a material having a high heat conductivity, such as a metal, so that heat generated by the heater 33 is conducted to the outer surface of the drum 30. A second heater unit 34 provides additional heating, as will be described in more detail below.

-The entire drum 30 is provided within a heat resistant housing 35. This helps reduce heat loss from the oven 7, thereby helping to maintain the operating temperature, as well as preventing the outside of the oven from becoming too hot.

Finally, a scraper 36 is positioned by the output transport mechanism 8 that is formed P \WPD0CSWS\pcci\76JX3 2 doc-M6A -6from the rollers 37 as shown.

Operation of the transport system 5, the spray system 6, the oven 7 and the output transport mechanism 8 will now be described.

Flattened discs of dough 40 received from the roller system 4 are transported by the conveyer belt 11 in the direction shown by the arrow 41.

As the flattened disk of dough 40 passes under the nozzle 10 this is detected by the sensor 14 that activates the nozzle. In use, the nozzle 10 is connected to a water supply (not shown) and operates to spray water onto the upper surface of the dough 12 so that at least part of the surface 40A is coated with a thin film of water.

The dough 40 is then transferred from the conveyer belt 11 to the conveyer belt 20, as shown. During this process, it is important that the conveyer belt 11 and the conveyer belt 20 move at equal speeds to thereby prevent deformation of the dough Accordingly, it is necessary for the speed of the rollers 21, 22, 23, 24, 25, 26 to be controlled using a suitable controller (not shown).

In operation the dough 40 is transferred from the conveyer belt 20 to the drum 30 by urging the conveyor belt 20 towards the drum 30 in the area 27. This action urges the dough 40 against heated drum 30, with the action of the heat on the wet upper surface of the dough 40A causing the dough to stick to the drum. Accordingly, the dough sticks to the drum as the drum rotates in the direction of the arrow 38, as shown.

Rotation of the drum is achieved by having the drum mounted to an axis 31 (shown in dotted lines in Figure which is in turn coupled to a motor 32, as shown. Again, it will be appreciated, that in order to prevent deformation of the dough, it is preferable for the surface of the drum 30 and the conveyer belt 20 to be moving at the same speeds.

P kWPDOCSVJS\scmA76IX320 doc-2M'A~ -7- In addition to this however, in order to ensure adequate cooking of the bread, the drum must 30 rotate at approximately one revolution per minute, so that the dough takes approximately 45 seconds to travel from the region 27 to the scraper 36.

As described above, in order for the dough 40 to be transferred to the drum, the conveyor belt 20 is urged towards the drum, in the direction of the arrow 27.

Accordingly, as the conveyor belt 20 remains in contact with the drum 30 for at least a portion of time, it is important that the conveyor belt 20 does not burn or melt at the operating temperature of the drum 30, which is typically above 300'C. Two different techniques are provided for protecting the integrity of the conveyor belt Firstly, the conveyor belt is formed from a multiple layer construction. In this case, the outermost layer is formed from a tough material that is able to stand wear associated with contact with the drum 30, and which may be cleaned easily to satisfy hygiene requirements. The middle layer is formed from a heat resistant material that is capable of preventing the heat from the drum 30 being transferred to the rollers 23, 24. Finally a third layer of material is positioned between the heat resistant layer and the rollers to protect the heat resistant layer from wear. The types of material used are not important and will be known by persons skilled in the art.

The second technique is to remove the conveyor belt 20 from contact with the drum when not in use, for example when the drum is being raised to operating temperatures. In order to achieve this, the rollers 23, 24, 25 are moveable to the position shown by the dotted lines, thereby disengaging the conveyor belt 20 from the drum In any event, once the dough 40 is transferred to the drum surface, the dough passes through the oven 7 stuck to the outer surface of the drum 30, as the drum rotates. As mentioned above, rotation of the drum is such that the dough remains in contact with the drum for approximately 45-50 seconds. During this time, the heat of the drum cooks the surface 40A of the dough 40. In addition to this, as the dough passes the P.kWPDOCS\.4s\,pi\761S320 dc-27 J- 2002 -8heater 34, heat generated by the heater operates to cook the other surface 40B of the dough 40, thereby ensuring both surfaces 40A, 40B of the dough are cooked.

Accordingly, when the dough reaches the scraper 36 the dough has been cooked to form a baked flat bread. The scraper 36 operates to urge the baked flat bread away from the drum 30 and onto the transport system 8 formed from the rollers 37. It will be appreciated that as the water on the surface 40A evaporates during the cooking, then the baked flat bread is no longer stuck to the drum with any degree of force and can therefore be easily removed.

The rollers 37 are driven and cause the flat bread to be transported away from the oven 7 to a packing station 9. At this point the bread can be packed into bags or boxes as required.

Accordingly, it will be appreciated that the above described system provides a system for automatically baking the bread by automatically inserting the bread into another and removing the bread once it is cooked. This is achieved by the operation of the drum 30 to receive the bread and then rotate whilst cooking the bread transferring the bread to the output.

Persons skilled in the art will appreciate that numerous variations and modifications will become apparent. All such variations and modifications which become apparent to persons skilled in the art, should be considered to fall within the spirit and scope of the invention as broadly hereinbefore described.