GB2083738A - Ovens - Google Patents

Abstract

An oven for baking biscuits having a casing (10) with an inlet (20) for an endless conveyor (22) on one side and an outlet (24) for the conveyor (22) on the other. The conveyor (22) carries a series of trays (T) which support the biscuits being cooked and there are upper and lower guides (26) inside the casing (10). The conveyor (22) passes over these guides (26) in a series of vertical runs. Heaters (28, 34) are provided top and bottom. The bottom heaters (28) are supplied with gas and the top heaters (34) are electric. Heating can also be provided by blowing hot air in via fan (42) and ensuring even distribution thereof by baffles (44, 46, 48, 50, 52). <IMAGE>

Description

SPECIFiCATION Ovens This invention relates to ovens.

According to the present invention, there is provided an oven comprising a casing, an endless conveyor for supporting the products to be baked, an upper group of guide means1 and a lower group of guide means for guiding the endless conveyor along a series of horizontally spaced, side-by-side runs within said casing, and at least one gas burner for heating the oven from the lower end thereof.

Preferably, said gas burner is below a metal plate and serves to heat the metal plate from which heat is radiated upwardly. The metal plate can comprise two parts located one above the other, with apertures in both parts, the plates being movable with respect to one another so that the apertures in the two -plates can be moved into or out or register with one another.

At least one electrical heating element-can be provided at the upper end of said casing for radiating heat downwardly onto the products carried by said conveyor.

If more than one electrical heating element is provided, thekn all the elements are connected into the same circuit and are controlled by the same thermostat and on-off switch.

Said endless conveyor can enter said casing via an opening in one wall thereof, and exit through an opening in the opposed wall thereof.

Said conveyor can comprise a series of trays for supporting the products to be baked. In a specific constructional form said conveyor comprises a pair of parallel chains and a series of pins, said trays being suspended from said pins. The chains can have apertures therein at regular intervals so that the pins can be positioned on the chains where desired.

Said conveyor can pass through a section in which products to be baked are placed on said trays and through a section in which the baked products are discharged from said trays, the sections being positioned one on each side of said casing and being displaceable towards and away from said casing.

For a better understanding of the present invention, reference will now be made by way of example to the accompanying drawing in which, Figure 1 is a diagrammatic vertical section through part of an oven in accordance with the present invention; and Figure 2 is a similar section through a further form of oven in accordance with the present invention.

The oven illustrated in Figure 1 comprises a heat-insulated casing 10 having a top wall 12, end walls 14, side walls 16 (only-one of which is shown), and a base 18. Near the loweredge-ofthe lefthand wall 14 there is an opening 20 through which an endless conveyor 22 enters the casing 10. Similarly, near the lower edge of the righthand wall 14, there is an opening 24 through which the-conveyor 22 leaves the casing 10.

The conveyor 22 comprises-two parallel chains (not shown), each of which has a plurality 6f regularly spaced apertures therein. Pins (not shown) are entered in these apertures at suitable intervals, and trays Ton which the products to be baked are supported, are suspended from these pins.

Upper and lower groups of guide means for the conveyor are provided. The upper group comprises pairs of chain wheels 26 at the upper end of the casing 10, and the lower group comprises further pairs of chain wheels 26 at the lower end of the casing 10. The chains of the conveyor 22 are entrained around these wheels so that, within the casing, the conveyor follows a series of horizontally spaced, side-by-side, verticaly extending runs.

At least one gas burner 28, and preferably a series of such burners, is provided near the lower end of the casing 10, these burners being below a metal plate 30.-The plate 30 is in two parts 30.1 and 30.2, located one above the other, with apertures 32 in each part. The parts are movable with respect to one another and, as they are displaced, the degree of overlap between the two sets of apertures 32 varies so that the apertures can be moved into and out of register. This in turn changes the quantity of heat which passes directly from the burners 28 to the main portion of the casing 10. Heat is also radiated upwardly from the plate 30.

The products to be cooked in the oven are usually biscuits. While these can be cooked satisfactorily by heat applied from the bottom, it is also necessry to 'brown' their tops. For this purpose an electrical heating element 34 is mounted below the top wall 12 of the casing, this element being connected to a thermostat (not shown) and an on-off switch. The single element 34 can, if desired, be replaced by a series of elements connected in parallel or in series.

However, a single thermostat and a single on-off switch are still used for control purposes.

Small apertures 36 are provided in the righthand wall 14 near the upper end thereof. These apertures form a hot air outlet and connect the interior of the casing 10 with a duct 38 which extends over the top wall 12 and downwardly on the outside of the lefthand wall 14. An electric motor 401s provided for driving a fan 42, the fan 42 being arranged so as to blow into the casing 10, hot air which enters the duct 38 through the apertures 36.

-To ensure that the hot air being blown into the oven is distributed in the desired manner, two baffles 44 and 46 can be provided. The baffle 44 is inclined and extends from below the level at which hot air is blown into the casing to a position just below the first of the upper chain wheels 26. The baffle 46 extends downwardly from the top wall 12 a a position adjacent the first of the lower chain wheels 26. Hot air entering the casing is thus directed upwardly by the baffle 44 and then downwardly by the baffle 46. While flowing downwardly, it impinges on the upper faces of the biscuits on the trays.

In an alternative constructional form, the baffle 46 is omitted and three further baffles 48, and 52 employed. The baffles 48,50 and 52 extend downwardly from the top wall 12, and are of different lengths. Hot air entering the casing flows upwardly over the baffle 44 and then horizontally, some of the incoming hot air being directed downwardly upon reaching the baffle 48, a further portion being directed downwardly by the baffle 50, and yet another portion being directed downwardly by the baffle 52. Thus, with this arrangement, the upper faces of the biscuits are subjected to downwardly flowing hot air for a considerable part of the time during which they are in the casing 10.

To the left of the casing 10, the oven includes a biscuit-making section (not shown) which places the biscuit dough on the trays of the conveyor 22. This type of apparatus conventionally includes mating rollers which, as they rotate, feed dough onto the trays, usually six pieces side-by-side, of the desired shape and size. To the right of the casing 10 the oven includes a discharge section at which the trays are tipped so that the cooked biscuits slide or fall onto a display area from where they are purchased.

The discharge section and the biscuit-making section can be moved towards and away from the casing 10, it being understood that the conveyor 22 must be appropriately lengthened or shortened if either of these sections is moved. The advantage of permitting such movement is that, if desired, the biscuit-making section and the casing 10 can be positioned in one room and the conveyor can pass through suitable apertures in a wall between that t;oom and anrea which is open to the public, for example, a supermarket shopping area.

During passage of the trays with the uncooked dough on them from the biscuit-making section to the casing 10, decorative items such as cherries, can be placed on the biscuits.

Cooling takes place between the casing 10 and the discharge section.

Turning now to Figure 2, the duct 38 in this form only extends across the top face of the top wall 12.

The motor 40 is mounted externally of the duct 38, and the fan 42 is within the duct 38. The top wall 12 is formed with a series of slots 54, each slot forming a hot air inlet. The fan 42 serves to extract hot air from the casing 10 and blow it into the duct 38 from which it returns to the casing 10 through the slots 54. The slots 54can increase in width from left to right. Thus, the largest slots 54 are adjacent the fan 42. The effect of this is to restrict flow of hot air through the lefthand slots 54 and cause more air to flow through the larger, righthand slots 54. In this way it is possible to obtain the desired equal distribution of hot air in the casing 10. Furthermore, each slot 54 is, in length, at least 'as long as the trays so that all the biscuits on the trays are subjected to downwardly flowing hot air.

If desired, the slots 54 can have shutters associated therewith so that, from externally of the casing 10, the slots 54 can be increased or decreased in effective width and hence in effective area. Thus, the operator can, by displacing the shutters, vary the air distribution if, during use of the oven, he finds that this is desirble.

Claims (14)

1. An oven comprising a casing, an endless conveyor for supporting the products tobe baked, an upper group of guide means and a lower group of guide means for guiding the endless conveyor along a series of horizontally spaced, side-by-side runs within said casing, and at least one gas burner for heating the oven from the lower end thereof.

2. An oven as claimed in Claim 1, wherein s,aid gas burner is below a metal plate and serves to heat the metal plate from which heat is radiated upwardly.

3. An oven as claimed in Claim 2, wherein the metal plate comprises two parts located one above the other with apertures in both part, the plates being movable with respect to one another that the apertures in the two plates can be moved into or out of register with one another.

4. An oven as claimed in Claim 1, or 3, wherein at least one electrical heating element is provided at the upper end of said casing for radiating heat downwardly onto products carried by said conveyor.

5. An oven as claimed in any preceding claim, wherein said endless conveyor enters said casing via an opening in one wall thereof and exits through an opening in the opposed wall thereof.

6. An oven as claimed in any preceding claim, in which said conveyor comprises a series of trays for supporting the products to be baked.

7. An oven as claimed in Claim 6, wherein said conveyor comprises a pair of parallel chains and a series of pins, said trays being suspended from said pins.

8. An oven as claimed in Claim 7, wherein the chains have apertures therein at regular intervals so that the pins can be positioned on the chains where desired.

9. An oven as claimed in any preceding claim, in which said.conveyor passes through a sectionin which products to be baked are placed on said trays and through a section in which the baked products are discharged from said trays, said sections being positioned one on each side of said casing and being displaceable towards and away from said casing.

10. An oven as claimed in any preceding claim, and including a hot air outlet from the casing, a series of hot air inlets, and a duct leading from the outlet to the inlets, said inlets being in the top wall of the casing so that, in use, air flows downwardly therethrough.

11. An oven as claimed in Claim 10, and including shutters for varying the effective areas of said hot air inlets.

12. An oven as claimed any of Claims 1 to 9, and including a hot air outlet from the casing, a hot air inlet to the casing, a duct leading from the hot air outlet to the hot air inlet, and a baffle within the casing for directing air entering via said hot air inlet to the upper end of the casing whereby, in us, air returned to the casing via said duct, flows downwardly within the casing.

13. An oven as claimed in Claim 10,11 or12, and including a fan for displacing hot air along said duct.

14. An oven substantially as hereinbefore described with reference to the accompanying drawing.